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Sample records for optimizing biogeochemical reduction

  1. Microbial Selenite Reduction and the Selenium Biogeochemical Cycle

    Science.gov (United States)

    Stolz, J. F.; Wells, M.

    2016-12-01

    Selenium is an essential trace element utilized by many species in the three domains of life. In most Bacteria and Archaea, selenium is primarily assimilated to form selenocysteine, the 21st amino acid (Sec). Additionally selenium can be methylated, demethylated, or used as a terminal electron acceptor in dissimilatory selenate or selenite reduction. Although progress has been made on elucidating the synthesis of selenoproteins, less is known of their occurrence, diversity, and functionality, primarily due to poor genome annotation (e.g., failure to recognize UGA as a Sec and not a stop codon) and proteomics analysis (e.g., failure to detect Sec in LC/MS-MS). Furthermore important parts of the selenium biogeochemical cycle remain to be fully explored, in particular the reduction of Se(IV) to Se(O). We have examined the selenoproteome of a selenate respiring bacterium Sulfurospirillum barnesii strain SES-3, which reduces Se(VI) to Se(0) and the dissimilatory selenite reducing bacterium, Bacillus selenitireducens, strain MLS-10, which reduces Se(IV) to Se(0). Candidate selenoproteins including D-proline reductase, formate dehydrogenase, and methionine-S sulfoxide reductase have been identified in the genomes. A putative dissimilatory selenate reducase (Ser) was found in the genome of S. barnesii. More significant was the discovery of a candidate for the respiratory selenite reductase in B. selenitireducens as determined by in gel assays and LC/MS-MS. The latter has provided a hint at the potential diversity of DSiR bacteria and the development of molecular probes for investigating DSiR in the selenium biogeochemical cycle.

  2. Finding optimal exact reducts

    KAUST Repository

    AbouEisha, Hassan M.

    2014-01-01

    The problem of attribute reduction is an important problem related to feature selection and knowledge discovery. The problem of finding reducts with minimum cardinality is NP-hard. This paper suggests a new algorithm for finding exact reducts with minimum cardinality. This algorithm transforms the initial table to a decision table of a special kind, apply a set of simplification steps to this table, and use a dynamic programming algorithm to finish the construction of an optimal reduct. I present results of computer experiments for a collection of decision tables from UCIML Repository. For many of the experimented tables, the simplification steps solved the problem.

  3. Parameter estimation and uncertainty quantification in a biogeochemical model using optimal experimental design methods

    Science.gov (United States)

    Reimer, Joscha; Piwonski, Jaroslaw; Slawig, Thomas

    2016-04-01

    The statistical significance of any model-data comparison strongly depends on the quality of the used data and the criterion used to measure the model-to-data misfit. The statistical properties (such as mean values, variances and covariances) of the data should be taken into account by choosing a criterion as, e.g., ordinary, weighted or generalized least squares. Moreover, the criterion can be restricted onto regions or model quantities which are of special interest. This choice influences the quality of the model output (also for not measured quantities) and the results of a parameter estimation or optimization process. We have estimated the parameters of a three-dimensional and time-dependent marine biogeochemical model describing the phosphorus cycle in the ocean. For this purpose, we have developed a statistical model for measurements of phosphate and dissolved organic phosphorus. This statistical model includes variances and correlations varying with time and location of the measurements. We compared the obtained estimations of model output and parameters for different criteria. Another question is if (and which) further measurements would increase the model's quality at all. Using experimental design criteria, the information content of measurements can be quantified. This may refer to the uncertainty in unknown model parameters as well as the uncertainty regarding which model is closer to reality. By (another) optimization, optimal measurement properties such as locations, time instants and quantities to be measured can be identified. We have optimized such properties for additional measurement for the parameter estimation of the marine biogeochemical model. For this purpose, we have quantified the uncertainty in the optimal model parameters and the model output itself regarding the uncertainty in the measurement data using the (Fisher) information matrix. Furthermore, we have calculated the uncertainty reduction by additional measurements depending on time

  4. Assessment of the GHG reduction potential from energy crops using a combined LCA and biogeochemical process models: a review.

    Science.gov (United States)

    Jiang, Dong; Hao, Mengmeng; Fu, Jingying; Wang, Qiao; Huang, Yaohuan; Fu, Xinyu

    2014-01-01

    The main purpose for developing biofuel is to reduce GHG (greenhouse gas) emissions, but the comprehensive environmental impact of such fuels is not clear. Life cycle analysis (LCA), as a complete comprehensive analysis method, has been widely used in bioenergy assessment studies. Great efforts have been directed toward establishing an efficient method for comprehensively estimating the greenhouse gas (GHG) emission reduction potential from the large-scale cultivation of energy plants by combining LCA with ecosystem/biogeochemical process models. LCA presents a general framework for evaluating the energy consumption and GHG emission from energy crop planting, yield acquisition, production, product use, and postprocessing. Meanwhile, ecosystem/biogeochemical process models are adopted to simulate the fluxes and storage of energy, water, carbon, and nitrogen in the soil-plant (energy crops) soil continuum. Although clear progress has been made in recent years, some problems still exist in current studies and should be addressed. This paper reviews the state-of-the-art method for estimating GHG emission reduction through developing energy crops and introduces in detail a new approach for assessing GHG emission reduction by combining LCA with biogeochemical process models. The main achievements of this study along with the problems in current studies are described and discussed.

  5. Investigation of In-situ Biogeochemical Reduction of Chlorinated Solvents in Groundwater by Reduced Iron Minerals

    Science.gov (United States)

    Biogeochemical transformation is a process in which chlorinated solvents are degraded abiotically by reactive minerals formed by, at least in part or indirectly from, anaerobic biological processes. Five mulch biowall and/or vegetable oil-based bioremediation applications for tr...

  6. Volume reduction outweighs biogeochemical processes in controlling phosphorus treatment in aged detention systems

    Science.gov (United States)

    Shukla, Asmita; Shukla, Sanjay; Annable, Michael D.; Hodges, Alan W.

    2017-08-01

    Stormwater detention areas (SDAs) play an important role in treating end-of-the-farm runoff in phosphorous (P) limited agroecosystems. Phosphorus transport from the SDAs, including those through subsurface pathways, are not well understood. The prevailing understanding of these systems assumes that biogeochemical processes play the primary treatment role and that subsurface losses can be neglected. Water and P fluxes from a SDA located in a row-crop farm were measured for two years (2009-2011) to assess the SDA's role in reducing downstream P loads. The SDA treated 55% (497 kg) and 95% (205 kg) of the incoming load during Year 1 (Y1, 09-10) and Year 2 (Y2, 10-11), respectively. These treatment efficiencies were similar to surface water volumetric retention (49% in Y1 and 84% in Y2) and varied primarily with rainfall. Similar water volume and P retentions indicate that volume retention is the main process controlling P loads. A limited role of biogeochemical processes was supported by low to no remaining soil P adsorption capacity due to long-term drainage P input. The fact that outflow P concentrations (Y1 = 368.3 μg L- 1, Y2 = 230.4 μg L- 1) could be approximated by using a simple mixing of rainfall and drainage P input further confirmed the near inert biogeochemical processes. Subsurface P losses through groundwater were 304 kg (27% of inflow P) indicating that they are an important source for downstream P. Including subsurface P losses reduces the treatment efficiency to 35% (from 61%). The aboveground biomass in the SDA contained 42% (240 kg) of the average incoming P load suggesting that biomass harvesting could be a cost-effective alternative for reviving the role of biogeochemical processes to enhance P treatment in aged, P-saturated SDAs. The 20-year present economic value of P removal through harvesting was estimated to be 341,000, which if covered through a cost share or a payment for P treatment services program could be a positive outcome for both

  7. Aggregate-scale spatial heterogeneity in reductive transformation of ferrihydrite resulting from coupled biogeochemical and physical processes

    Science.gov (United States)

    Pallud, C.; Masue-Slowey, Y.; Fendorf, S.

    2010-05-01

    Iron (hydr)oxides are ubiquitous in soils and sediments and play a dominant role in the geochemistry of surface and subsurface environments. Their fate depends on local environmental conditions, which in structured soils may vary significantly over short distances due to mass-transfer limitations on solute delivery and metabolite removal. In the present study, artificial soil aggregates were used to investigate the coupling of physical and biogeochemical processes affecting the spatial distribution of iron (Fe) phases resulting from reductive transformation of ferrihydrite. Spherical aggregates made of ferrihydrite-coated sand were inoculated with the dissimilatory Fe-reducing bacterium Shewanella putrefaciens strain CN-32, and placed into a flow reactor, the reaction cell simulates a diffusion-dominated soil aggregate surrounded by an advective flow domain. The spatial and temporal evolution of secondary mineralization products resulting from dissimilatory Fe reduction of ferrihydrite were followed within the aggregates in response to a range of flow rates and lactate concentrations. Strong radial variations in the distribution of secondary phases were observed owing to diffusively controlled delivery of lactate and efflux of Fe(II) and bicarbonate. In the aggregate cortex, only limited formation of secondary Fe phases were observed over 30 d of reaction, despite high rates of ferrihydrite reduction. Under all flow conditions tested, ferrihydrite transformation was limited in the cortex (70-85 mol.% Fe remained as ferrihydrite) because metabolites such as Fe(II) and bicarbonate were efficiently removed in outflow solutes. In contrast, within the inner fractions of the aggregate, limited mass-transfer results in metabolite (Fe(II) and bicarbonate) build-up and the consummate transformation of ferrihydrite - only 15-40 mol.% Fe remained as ferrihydrite after 30 d of reaction. Goethite/lepidocrocite, and minor amounts of magnetite, formed in the aggregate mid

  8. Delay Reduction in Optimized Reversible Multiplier Circuit

    Directory of Open Access Journals (Sweden)

    Mohammad Assarian

    2012-01-01

    Full Text Available In this study a novel reversible multiplier is presented. Reversible logic can play a significant role in computer domain. This logic can be applied in quantum computing, optical computing processing, DNA computing, and nanotechnology. One condition for reversibility of a computable model is that the number of input equate with the output. Reversible multiplier circuits are the circuits used frequently in computer system. For this reason, optimization in one reversible multiplier circuit can reduce its volume of hardware on one hand and increases the speed in a reversible system on the other hand. One of the important parameters that optimize a reversible circuit is reduction of delays in performance of the circuit. This paper investigates the performance characteristics of the gates, the circuits and methods of optimizing the performance of reversible multiplier circuits. Results showed that reduction of the reversible circuit layers has lead to improved performance due to the reduction of the propagation delay between input and output period. All the designs are in the nanometric scales.

  9. Land use, climate and biogeochemical cycles. Feedbacks and options for emission reduction

    Energy Technology Data Exchange (ETDEWEB)

    Hutjes, R.W.A.; Dolman, A.J.; Nabuurs, G.J.; Schelhaas, M.J.; Ter Maat, H.W.; Kabat, P.; Moors, E.; Huygen, J. [Alterra, Wageningen (Netherlands); Haarsma, R.; Ronda, R.; Schaeffer, M.; Opsteegh, J.D. [RoyalNetherlands Meteorological Institute KNMI, De Bilt (Netherlands); Leemans, R.; Strengers, B.; De Vries, B.; Bouwman, L.; Busch, G.; Eickhout, E.; Kreileman, E. [National Institute for Public Health and Environment RIVM, Bilthoven (Netherlands); Verhagen, A.; Vleeshouwers, L.; Corre, W.J.; Jongschaap, R.E.E. [Plant Research International PRI, Wageningen (Netherlands); Kruseman, G.; Van Ierland, E.; Holtslag, A.A.M. [Wageningen University, Wageningen (Netherlands); Willemsen, F.; Dorland, C.; Van Tol, R.S.J. [Institute for Environmental Studies IVM, Amsterdam University, Amsterdam (Netherlands)

    2001-12-01

    The approach of this study has been to try to understand the coupling between the main driving forces of land use change and the emission of greenhouse gasses in the context of coupled land surface climate models. Studies related to investigating the main driving forces of land use change in Europe and assessing the budgets of the main greenhouse gasses in Europe were combined with sensitivity studies of land use change and climate at regional and global scale. We tried to link these to an integrated assessment model and selected economic analysis. In a two-year project, this appeared difficult. However, some important steps have been set to generate a framework that addressed these questions. The most salient conclusions for each of the sub studies are: The Common Agricultural Policy of the EU is the single most important element in shaping land use in Europe; The new estimate of the stocks and fluxes of carbon in Europe is lower that usually quoted by individual countries submission to UNFCCC; Reduction of methane emissions by agriculture is in the short term a good option in West Europe to reduce GHG emissions; Coupled climate land surface model runs at regional scale suggest that effects of planting large areas with forest may have effects on precipitation, but also increase warming; Coupled climate land surface model runs at global scale suggest that effects of planting large areas with forest may have opposite effects on precipitation in tropical and extra tropical areas, and increase warming in northern areas; Measures to increase biofuel production would lead to modest increases in Western Europe, but to huge increases in areas where the current land uses are low-value uses; Regional assessments have to be embedded in global scenarios to illustrate the effects of increasing globalisation of trade flows; Changes in regional land cover appear to have marginal effects on the global carbon cycle. At regional scale they may be important. The overall study

  10. Biogeochemical Cycling

    Science.gov (United States)

    Bebout, Brad; Fonda, Mark (Technical Monitor)

    2002-01-01

    This lecture will introduce the concept of biogeochemical cycling. The roles of microbes in the cycling of nutrients, production and consumption of trace gases, and mineralization will be briefly introduced.

  11. Optimization of a biological sulfate reduction process

    Energy Technology Data Exchange (ETDEWEB)

    Lebel, A.

    1985-01-01

    A biological sulfate reduction process is presented. It is intended to treat sulfate wastes by converting them to hydrogen sulfide which can be further oxidized to elemental sulfur. An optimization study of a completely-mixed reactor system was performed. Major operating parameters were determined at the bench-scale level. The study was conducted in batch-culture experiments, using a mixed Desulfovibrio culture from sewage. Kinetic values were extrapolated using the Michaelis-Menten model, which best fitted the experimental data. The iron loading and the sulfate loading significantly affected the growth and metabolism of sulfate reducing bacteria (SRB). A model to determine V/sub m/ from the iron and sulfate loading values was explored. The model is limited by sulfate loading greater than 4.3 g/l, where bacterial growth is inhibited. Iron loading is not anticipated to suppress the bacterial metabolism efficiency since it remained in the linear pattern even at inhibition levels. Studies of the metabolic behavior of SRB, using lactic acid as the carbon source, showed a requirement of 2.7 moles of lactate for each mole of sulfate. This technique and its application to the sulfur recovery process are discussed.

  12. Enhanced biogeochemical cycling and subsequent reduction of hydraulic conductivity associated with soil-layer interfaces in the vadose zone.

    Science.gov (United States)

    Hansen, David J; McGuire, Jennifer T; Mohanty, Binayak P

    2011-01-01

    Biogeochemical dynamics in the vadose zone are poorly understood due to the transient nature of chemical and hydrologic conditions but are nonetheless critical to understanding chemical fate and transport. This study explored the effects of a soil layer on linked geochemical, hydrological, and microbiological processes. Three laboratory soil columns were constructed: a homogenized medium-grained sand, a homogenized organic-rich loam, and a sand-over-loam layered column. Upward and downward infiltration of water was evaluated during experiments to simulate rising water table and rainfall events, respectively. In situ collocated probes measured soil water content, matric potential, and Eh. Water samples collected from the same locations were analyzed for Br, Cl, NO, SO, NH, Fe, and total sulfide. Compared with homogeneous columns, the presence of a soil layer altered the biogeochemistry and water flow of the system considerably. Enhanced biogeochemical cycling was observed in the layered column over the texturally homogeneous soil columns. Enumerations of iron- and sulfate-reducing bacteria showed 1 to 2 orders of magnitude greater community numbers in the layered column. Mineral and soil aggregate composites were most abundant near the soil-layer interface, the presence of which likely contributed to an observed order-of-magnitude decrease in hydraulic conductivity. These findings show that quantifying coupled hydrologic-biogeochemical processes occurring at small-scale soil interfaces is critical to accurately describing and predicting chemical changes at the larger system scale. These findings also provide justification for considering soil layering in contaminant fate and transport models because of its potential to increase biodegradation or to slow the rate of transport of contaminants.

  13. Biogeochemical reductive release of soil embedded arsenate around a crater area (Guandu) in northern Taiwan using X-ray absorption near-edge spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Kai-Ying Chiang; Tsan-Yao Chen; Chih-Hao Lee; Tsang-Lang Lin; Ming-Kuang Wang; Ling-Yun Jang; Jyh-Fu Lee

    2013-01-01

    This study investigates biogeochemical reductive release of arsenate from beudantite into solution in a crater area in northern Taiwan,using a combination of X-ray absorption near-edge structure (XANES) and atomic absorption spectrometry.Total arsenic (As)concentrations in the soil were more than 200 mg/kg.Over four months of laboratory experiments,less than 0.8% As was released into solution after reduction experiments.The 71% to 83% As was chemically reduced into arsenite (As(Ⅲ)) and partially weathering into the soluble phase.The kinetic dissolution and re-precipitation of As,Fe,Pb and sulfate in this area of paddy soils merits further study.

  14. Design Optimization of Marine Reduction Gears.

    Science.gov (United States)

    1983-09-01

    Approved by: A t/ 6 𔃼 -A-,i Thesis Advisor Second Reader Chairman,De rtment or Mecanica Engineering I De&n of Science and Engineering 3...unconstrained problems. 1. Direct Methods Direct methods are popular constrained optimization algorithms. One well known direct method is the method of...various popular tooth forms and Appendix A contains a descriptive figure of gear tooth design variables. However, the following equations are a good

  15. Optimal Hankel Norm Model Reduction by Truncation of Trajectories

    NARCIS (Netherlands)

    Roorda, B.; Weiland, S.

    2000-01-01

    We show how optimal Hankel-norm approximations of dynamical systems allow for a straightforward interpretation in terms of system trajectories. It is shown that for discrete time single-input systems optimal reductions are obtained by cutting 'balanced trajectories', i.e., by disconnecting the past

  16. Optimal angle reduction - a behavioral approach to linear system approximation

    NARCIS (Netherlands)

    Roorda, Berend; Fuhrmann, P.A.

    2001-01-01

    We investigate the problem of optimal state reduction under minimization of the angle between system behaviors. The angle is defined in a worst-case sense, as the largest angle that can occur between a system trajectory and its optimal approximation in the reduced-order model. This problem is analyz

  17. Throughput Optimal Scheduling with Feedback Cost Reduction

    CERN Document Server

    Karaca, Mehmet; Ercetin, Ozgur; Alpcan, Tansu; Boche, Holger

    2012-01-01

    It is well known that opportunistic scheduling algorithms are throughput optimal under full knowledge of channel and network conditions. However, these algorithms achieve a hypothetical achievable rate region which does not take into account the overhead associated with channel probing and feedback required to obtain the full channel state information at every slot. We adopt a channel probing model where $\\beta$ fraction of time slot is consumed for acquiring the channel state information (CSI) of a single channel. In this work, we design a joint scheduling and channel probing algorithm named SDF by considering the overhead of obtaining the channel state information. We analytically prove that when the number of users in the network is greater than 3, then SDF algorithm can achieve $1+\\epsilon$ of the full rate region achieved when all users are probed. We also demonstrate numerically in a realistic simulation setting that this rate region can be achieved by probing only less than 50% of all channels in a CDM...

  18. Chromium Isotopic Fractionation During Biogeochemical Cr (IV) Reduction in Hanford Sediment Column Experiments with Native Aquifer Microbial Communities

    Science.gov (United States)

    Qin, L.; Christensen, J. N.; Brown, S. T.; Yang, L.; Conrad, M. E.; Sonnenthal, E. L.; Beller, H. R.

    2010-12-01

    Hexavalent Chromium contamination in groundwater within the DOE complex, including the Hanford 100D and 100H sites has been a long-standing issue. It has been established that certain bacteria (including denitrifying and sulfate-reducing bacteria) harbor enzymes that catalyze Cr(VI) reduction to relatively nontoxic Cr(III). Microbial reduction of Cr(VI) also occurs indirectly by products of microbial respiration, such as sulfide and Fe(II). Chromium isotopes can be fractionated during Cr(VI) reduction and provides a potential basis for characterizing and discriminating between different microbial metabolic and geochemical pathways associated with Cr(VI) reductive immobilization. Addition of electron donor to contaminated groundwater systems to create conditions favorable for reductive metal immobilization has become a widely utilized remediation practice. We conducted a series of small-scale column experiments with homogenized material from the Hanford 100H aquifer to examine the effects of differing electron acceptors on local microbial communities. All columns have a continuous inflow of solutions with constant concentrations of Cr(VI), lactate (electron donor), and the appropriate electron acceptor (e.g. nitrate or sulfate). The Cr isotopic composition in the effluent was measured using a 50-54 double-spike technique and a Triton TIMS. Cr concentration measurements showed that the greatest Cr(VI) reduction occurred in the sulfate columns. Our preliminary Cr isotopic data show that under these conditions the delta 53Cr value increased from close to 0 to 4 per mil while the Cr concentration decreased from 260 ppb to 30 ppb in the effluent. This yields an apparent fractionation factor of 0.9979 (2.1 per mil). A decrease in Cr concentration from 260 ppb to 190 ppb in a nitrate-reducing column was accompanied by an increase of 1 per mil in delta 53Cr. Further Cr isotopic data will be presented and the effects of differing flow rates and electron acceptors will be

  19. An optimization approach to kinetic model reduction for combustion chemistry

    CERN Document Server

    Lebiedz, Dirk

    2013-01-01

    Model reduction methods are relevant when the computation time of a full convection-diffusion-reaction simulation based on detailed chemical reaction mechanisms is too large. In this article, we review a model reduction approach based on optimization of trajectories and show its applicability to realistic combustion models. As most model reduction methods, it identifies points on a slow invariant manifold based on time scale separation in the dynamics of the reaction system. The numerical approximation of points on the manifold is achieved by solving a semi-infinite optimization problem, where the dynamics enter the problem as constraints. The proof of existence of a solution for an arbitrarily chosen dimension of the reduced model (slow manifold) is extended to the case of realistic combustion models including thermochemistry by considering the properties of proper maps. The model reduction approach is finally applied to three models based on realistic reaction mechanisms: 1. ozone decomposition as a small t...

  20. Optimal deployment of emissions reduction technologies for construction equipment.

    Science.gov (United States)

    Bari, Muhammad Ehsanul; Zietsman, Josias; Quadrifoglio, Luca; Farzaneh, Mohamadreza

    2011-06-01

    The objective of this research was to develop a multiobjective optimization model to deploy emissions reduction technologies for nonroad construction equipment to reduce emissions in a cost-effective and optimal manner. Given a fleet of construction equipment emitting different pollutants in the nonattainment (NA) and near -nonattainment (NNA) counties of a state and a set of emissions reduction technologies available for installation on equipment to control pollution/emissions, the model assists in determining the mix of technologies to be deployed so that maximum emissions reduction and fuel savings are achieved within a given budget. Three technologies considered for emissions reduction were designated as X, Y, and Z to keep the model formulation general so that it can be applied for any other set of technologies. Two alternative methods of deploying these technologies on a fleet of equipment were investigated with the methods differing in the technology deployment preference in the NA and NNA counties. The model having a weighted objective function containing emissions reduction benefits and fuel-saving benefits was programmed with C++ and ILOG-CPLEX. For demonstration purposes, the model was applied for a selected construction equipment fleet owned by the Texas Department of Transportation, located in NA and NNA counties of Texas, assuming the three emissions reduction technologies X, Y, and Z to represent, respectively, hydrogen enrichment, selective catalytic reduction, and fuel additive technologies. Model solutions were obtained for varying budget amounts to test the sensitivity of emissions reductions and fuel-savings benefits with increasing the budget. Different mixes of technologies producing maximum oxides of nitrogen (NO(x)) reductions and total combined benefits (emissions reductions plus fuel savings) were indicated at different budget ranges. The initial steep portion of the plots for NO(x) reductions and total combined benefits against budgets

  1. Optimal entanglement witnesses from generalized reduction and Robertson maps

    Energy Technology Data Exchange (ETDEWEB)

    Chruscinski, Dariusz; Pytel, Justyna, E-mail: darch@fizyka.umk.pl [Institute of Physics, Nicolaus Copernicus University, Grudziadzka 5/7, 87-100 Torun (Poland)

    2011-04-22

    We provide a generalization of the reduction and Robertson positive maps in matrix algebras. They give rise to a new class of optimal entanglement witnesses. Their structural physical approximation is analyzed. As a byproduct we provide new examples of PPT (positive partial transpose) entangled states.

  2. Optimal entanglement witnesses from generalized reduction and Robertson maps

    CERN Document Server

    Chruściński, Dariusz

    2010-01-01

    We provide a generalization of the reduction and Robertson positive maps in matrix algebras. They give rise to a new class of optimal entanglement witnesses. Their structural physical approximations is analyzed. As a byproduct we provide a new examples of PPT (Positive Partial Transpose) entangled states.

  3. Optimal entanglement witnesses from generalized reduction and Robertson maps

    Science.gov (United States)

    Chruściński, Dariusz; Pytel, Justyna

    2011-04-01

    We provide a generalization of the reduction and Robertson positive maps in matrix algebras. They give rise to a new class of optimal entanglement witnesses. Their structural physical approximation is analyzed. As a byproduct we provide new examples of PPT (positive partial transpose) entangled states.

  4. Environmental Optimization Using the WAste Reduction Algorithm (WAR)

    Science.gov (United States)

    Traditionally chemical process designs were optimized using purely economic measures such as rate of return. EPA scientists developed the WAste Reduction algorithm (WAR) so that environmental impacts of designs could easily be evaluated. The goal of WAR is to reduce environme...

  5. Environmental Optimization Using the WAste Reduction Algorithm (WAR)

    Science.gov (United States)

    Traditionally chemical process designs were optimized using purely economic measures such as rate of return. EPA scientists developed the WAste Reduction algorithm (WAR) so that environmental impacts of designs could easily be evaluated. The goal of WAR is to reduce environme...

  6. Complexity Reduction in the Use of Evolutionary Algorithms to Function Optimization: A Variable Reduction Strategy

    Directory of Open Access Journals (Sweden)

    Guohua Wu

    2013-01-01

    Full Text Available Discovering and utilizing problem domain knowledge is a promising direction towards improving the efficiency of evolutionary algorithms (EAs when solving optimization problems. We propose a knowledge-based variable reduction strategy (VRS that can be integrated into EAs to solve unconstrained and first-order derivative optimization functions more efficiently. VRS originates from the knowledge that, in an unconstrained and first-order derivative optimization function, the optimal solution locates in a local extreme point at which the partial derivative over each variable equals zero. Through this collective of partial derivative equations, some quantitative relations among different variables can be obtained. These variable relations have to be satisfied in the optimal solution. With the use of such relations, VRS could reduce the number of variables and shrink the solution space when using EAs to deal with the optimization function, thus improving the optimizing speed and quality. When we apply VRS to optimization problems, we just need to modify the calculation approach of the objective function. Therefore, practically, it can be integrated with any EA. In this study, VRS is combined with particle swarm optimization variants and tested on several benchmark optimization functions and a real-world optimization problem. Computational results and comparative study demonstrate the effectiveness of VRS.

  7. QUADRO: A SUPERVISED DIMENSION REDUCTION METHOD VIA RAYLEIGH QUOTIENT OPTIMIZATION.

    Science.gov (United States)

    Fan, Jianqing; Ke, Zheng Tracy; Liu, Han; Xia, Lucy

    We propose a novel Rayleigh quotient based sparse quadratic dimension reduction method-named QUADRO (Quadratic Dimension Reduction via Rayleigh Optimization)-for analyzing high-dimensional data. Unlike in the linear setting where Rayleigh quotient optimization coincides with classification, these two problems are very different under nonlinear settings. In this paper, we clarify this difference and show that Rayleigh quotient optimization may be of independent scientific interests. One major challenge of Rayleigh quotient optimization is that the variance of quadratic statistics involves all fourth cross-moments of predictors, which are infeasible to compute for high-dimensional applications and may accumulate too many stochastic errors. This issue is resolved by considering a family of elliptical models. Moreover, for heavy-tail distributions, robust estimates of mean vectors and covariance matrices are employed to guarantee uniform convergence in estimating non-polynomially many parameters, even though only the fourth moments are assumed. Methodologically, QUADRO is based on elliptical models which allow us to formulate the Rayleigh quotient maximization as a convex optimization problem. Computationally, we propose an efficient linearized augmented Lagrangian method to solve the constrained optimization problem. Theoretically, we provide explicit rates of convergence in terms of Rayleigh quotient under both Gaussian and general elliptical models. Thorough numerical results on both synthetic and real datasets are also provided to back up our theoretical results.

  8. H∞ Optimal Model Reduction for Singular Fast Subsystems

    Institute of Scientific and Technical Information of China (English)

    WANGJing; ZHANGQing-Ling; LIUWan-Quan; ZHOUYue

    2005-01-01

    In this paper, H∞ optimal model reduction for singular fast subsystems will be investigated. First, error system is established to measure the error magnitude between the original and reduced systems, and it is demonstrated that the new feature for model reduction of singular systems is to make H∞ norm of the error system finite and minimal. The necessary and sufficient condition is derived for the existence of the H∞ suboptimal model reduction problem. Next, we give an exactand practicable algorithm to get the parameters of the reduced subsystems by applying the matrix theory. Meanwhile, the reduced system may be also impulsive. The advantages of the proposed algorithm are that it is more flexible in a straight-forward way without much extra computation, and the order of the reduced systems is as minimal as possible. Finally, one illustrative example is given to illustrate the effectiveness of the proposed model reduction approach.

  9. Model reduction for optimization of structural-acoustic coupling problems

    DEFF Research Database (Denmark)

    Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Brunskog, Jonas;

    2016-01-01

    , which becomes highly time consuming since many iterations may be required. The use of model reduction techniques to speed up the computations is studied in this work. The Component Mode Synthesis (CMS) method and the Multi-Model Reduction (MMR) method are adapted for problems with structure......Fully coupled structural-acoustic models of complex systems, such as those used in the hearing aid field, may have several hundreds of thousands of nodes. When there is a strong structure-acoustic interaction, performing optimization on one part requires the complete model to be taken into account...

  10. SVM-based glioma grading: Optimization by feature reduction analysis.

    Science.gov (United States)

    Zöllner, Frank G; Emblem, Kyrre E; Schad, Lothar R

    2012-09-01

    We investigated the predictive power of feature reduction analysis approaches in support vector machine (SVM)-based classification of glioma grade. In 101 untreated glioma patients, three analytic approaches were evaluated to derive an optimal reduction in features; (i) Pearson's correlation coefficients (PCC), (ii) principal component analysis (PCA) and (iii) independent component analysis (ICA). Tumor grading was performed using a previously reported SVM approach including whole-tumor cerebral blood volume (CBV) histograms and patient age. Best classification accuracy was found using PCA at 85% (sensitivity=89%, specificity=84%) when reducing the feature vector from 101 (100-bins rCBV histogram+age) to 3 principal components. In comparison, classification accuracy by PCC was 82% (89%, 77%, 2 dimensions) and 79% by ICA (87%, 75%, 9 dimensions). For improved speed (up to 30%) and simplicity, feature reduction by all three methods provided similar classification accuracy to literature values (∼87%) while reducing the number of features by up to 98%.

  11. Central Plant Optimization for Waste Energy Reduction (CPOWER). ESTCP Cost and Performance Report

    Science.gov (United States)

    2016-12-01

    EW-201349) Central Plant Optimization for Waste Energy Reduction (CPOWER) December 2016 This document has been cleared for public release...Optimization for Waste Energy Reduction (CPOWER) Girija Parthasarathy Honeywell Honeywell - 1985 Douglas Drive North, Golden Valley, MN 55422 ERDC...technology that commands all equipment in a central plant. Central Plant Optimization for Waste Energy Reduction (CPOWER), Building Automation System (BAS

  12. SVM-based glioma grading. Optimization by feature reduction analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zoellner, Frank G.; Schad, Lothar R. [University Medical Center Mannheim, Heidelberg Univ., Mannheim (Germany). Computer Assisted Clinical Medicine; Emblem, Kyrre E. [Massachusetts General Hospital, Charlestown, A.A. Martinos Center for Biomedical Imaging, Boston MA (United States). Dept. of Radiology; Harvard Medical School, Boston, MA (United States); Oslo Univ. Hospital (Norway). The Intervention Center

    2012-11-01

    We investigated the predictive power of feature reduction analysis approaches in support vector machine (SVM)-based classification of glioma grade. In 101 untreated glioma patients, three analytic approaches were evaluated to derive an optimal reduction in features; (i) Pearson's correlation coefficients (PCC), (ii) principal component analysis (PCA) and (iii) independent component analysis (ICA). Tumor grading was performed using a previously reported SVM approach including whole-tumor cerebral blood volume (CBV) histograms and patient age. Best classification accuracy was found using PCA at 85% (sensitivity = 89%, specificity = 84%) when reducing the feature vector from 101 (100-bins rCBV histogram + age) to 3 principal components. In comparison, classification accuracy by PCC was 82% (89%, 77%, 2 dimensions) and 79% by ICA (87%, 75%, 9 dimensions). For improved speed (up to 30%) and simplicity, feature reduction by all three methods provided similar classification accuracy to literature values ({proportional_to}87%) while reducing the number of features by up to 98%. (orig.)

  13. Spatial optimization of watershed management practices for nitrogen load reduction using a modeling-optimization framework.

    Science.gov (United States)

    Yang, Guoxiang; Best, Elly P H

    2015-09-15

    Best management practices (BMPs) can be used effectively to reduce nutrient loads transported from non-point sources to receiving water bodies. However, methodologies of BMP selection and placement in a cost-effective way are needed to assist watershed management planners and stakeholders. We developed a novel modeling-optimization framework that can be used to find cost-effective solutions of BMP placement to attain nutrient load reduction targets. This was accomplished by integrating a GIS-based BMP siting method, a WQM-TMDL-N modeling approach to estimate total nitrogen (TN) loading, and a multi-objective optimization algorithm. Wetland restoration and buffer strip implementation were the two BMP categories used to explore the performance of this framework, both differing greatly in complexity of spatial analysis for site identification. Minimizing TN load and BMP cost were the two objective functions for the optimization process. The performance of this framework was demonstrated in the Tippecanoe River watershed, Indiana, USA. Optimized scenario-based load reduction indicated that the wetland subset selected by the minimum scenario had the greatest N removal efficiency. Buffer strips were more effective for load removal than wetlands. The optimized solutions provided a range of trade-offs between the two objective functions for both BMPs. This framework can be expanded conveniently to a regional scale because the NHDPlus catchment serves as its spatial computational unit. The present study demonstrated the potential of this framework to find cost-effective solutions to meet a water quality target, such as a 20% TN load reduction, under different conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Feedback Reduction in Uplink MIMO OFDM Systems by Chunk Optimization

    Directory of Open Access Journals (Sweden)

    Arogyaswami Paulraj

    2008-01-01

    Full Text Available The performance of multiuser MIMO systems can be significantly increased by channel-aware scheduling and signal processing at the transmitters based on channel state information. In the multipleantenna uplink multicarrier scenario, the base station decides centrally on the optimal signal processing and spectral power allocation as well as scheduling. An interesting challenge is the reduction of the overhead in order to inform the mobiles about their transmit strategies. In this work, we propose to reduce the feedback by chunk processing and quantization. We maximize the weighted sum rate of a MIMO OFDM MAC under individual power constraints and chunk size constraints. An efficient iterative algorithm is developed and convergence is proved. The feedback overhead as a function of the chunk size is considered in the rate computation and the optimal chunk size is determined by numerical simulations for various channel models. Finally, the issues of finite modulation and coding schemes as well as quantization of the precoding matrices are addressed.

  15. Biogeochemical fluxes through microzooplankton

    National Research Council Canada - National Science Library

    Erik T. Buitenhuis; Richard B. Rivkin; Sévrine Sailley; Corinne Le Quéré

    2010-01-01

    ... mortality rate, and phytoplankton growth rate. We used these observations to parameterize and evaluate the microzooplankton compartment in a global biogeochemical model that represents five plankton functional types...

  16. Iterative metal artifact reduction: Evaluation and optimization of technique

    Energy Technology Data Exchange (ETDEWEB)

    Subhas, Naveen; Gupta, Amit; Polster, Joshua M. [Imaging Institute, Cleveland Clinic, Cleveland, OH (United States); Primak, Andrew N. [Siemens Medical Solutions USA Inc., Malvern, PA (United States); Obuchowski, Nancy A. [Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH (United States); Krauss, Andreas [Siemens Healthcare, Forchheim (Germany); Iannotti, Joseph P. [Orthopaedic and Rheumatologic Institute, Cleveland Clinic, Cleveland, OH (United States)

    2014-12-15

    Iterative metal artifact reduction (IMAR) is a sinogram inpainting technique that incorporates high-frequency data from standard weighted filtered back projection (WFBP) reconstructions to reduce metal artifact on computed tomography (CT). This study was designed to compare the image quality of IMAR and WFBP in total shoulder arthroplasties (TSA); determine the optimal amount of WFBP high-frequency data needed for IMAR; and compare image quality of the standard 3D technique with that of a faster 2D technique. Eight patients with nine TSA underwent CT with standardized parameters: 140 kVp, 300 mAs, 0.6 mm collimation and slice thickness, and B30 kernel. WFBP, three 3D IMAR algorithms with different amounts of WFBP high-frequency data (IMARlo, lowest; IMARmod, moderate; IMARhi, highest), and one 2D IMAR algorithm were reconstructed. Differences in attenuation near hardware and away from hardware were measured and compared using repeated measures ANOVA. Five readers independently graded image quality; scores were compared using Friedman's test. Attenuation differences were smaller with all 3D IMAR techniques than with WFBP (p < 0.0063). With increasing high-frequency data, the attenuation difference increased slightly (differences not statistically significant). All readers ranked IMARmod and IMARhi more favorably than WFBP (p < 0.05), with IMARmod ranked highest for most structures. The attenuation difference was slightly higher with 2D than with 3D IMAR, with no significant reader preference for 3D over 2D. IMAR significantly decreases metal artifact compared to WFBP both objectively and subjectively in TSA. The incorporation of a moderate amount of WFBP high-frequency data and use of a 2D reconstruction technique optimize image quality and allow for relatively short reconstruction times. (orig.)

  17. Calibration of Daycent biogeochemical model for rice paddies in three agro-ecological zones in Peninsular India to optimize cropping practices and predict GHG emissions

    Science.gov (United States)

    Rajan, S.; Kritee, K.; Keough, C.; Parton, W. J.; Ogle, S. M.

    2014-12-01

    Rice is a staple for nearly half of the world population with irrigated and rainfed lowland rice accounting for about 80% of the worldwide harvested rice area. Increased atmospheric CO2 and rising temperatures are expected to adversely affect rice yields by the end of the 21st century. In addition, different crop management practices affect methane and nitrous oxide emissions from rice paddies antagonistically warranting a review of crop management practices such that farmers can adapt to the changing climate and also help mitigate climate change. The Daily DayCent is a biogeochemical model that operates on a daily time step, driven by four ecological drivers, i.e. climate, soil, vegetation, and management practices. The model is widely used to simulate daily fluxes of various gases, plant productivity, nutrient availability, and other ecosystem parameters in response to changes in land management and climate. We employed the DayCent model as a tool to optimize rice cropping practices in Peninsular India so as to develop a set of farming recommendations to ensure a triple win (i.e. higher yield, higher profit and lower GHG emissions). We applied the model to simulate both N2O and CH4 emissions, and crop yields from four rice paddies in three different agro-ecological zones under different management practices, and compared them with measured GHG and yield data from these plots. We found that, like all process based models, the biggest constraint in using the model was input data acquisition. Lack of accurate documentation of historic land use and management practices, missing historical daily weather data, and difficulty in obtaining digital records of soil and crop/vegetation parameters related to our experimental plots came in the way of our execution of this model. We will discuss utilization of estimates based on available literature, or knowledge-based values in lieu of missing measured parameters in our simulations with DayCent which could prove to be a

  18. Central Plant Optimization for Waste Energy Reduction (CPOWER)

    Science.gov (United States)

    2016-12-01

    by connecting it with local plant control to enable real- time optimization based on current state of the plant, load and weather conditions. The...11 2.1.5 Solution Architecture ...Optimization Implementation........................................................................................ 10 Figure 3: System Architecture

  19. Optimizing Metalloporphyrin-Catalyzed Reduction Reactions for In Situ Remediation of DOE Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Schlautman, Mark A. [Clemson University, Clemson, SC (United States)

    2013-07-14

    Past activities have resulted in a legacy of contaminated soil and groundwater at Department of Energy facilities nationwide. Uranium and chromium are among the most frequently encountered and highest-priority metal and radionuclide contaminants at DOE installations. Abiotic chemical reduction of uranium and chromium at contaminated DOE sites can be beneficial because the reduced metal species are less soluble in water, less mobile in the environment, and less toxic to humans and ecosystems. Although direct biological reduction has been reported for U(VI) and Cr(VI) in laboratory studies and at some field sites, the reactions can sometimes be slow or even inhibited due to unfavorable environmental conditions. One promising approach for the in-situ remediation of DOE contaminants is to develop electron shuttle catalysts that can be delivered precisely to the specific subsurface locations where contaminants reside. Previous research has shown that reduction of oxidized organic and inorganic contaminants often can be catalyzed by electron shuttle systems. Metalloporphyrins and their derivatives are well known electron shuttles for many biogeochemical systems, and thus were selected to study their catalytic capabilities for the reduction of chromium and uranium in the presence of reducing agents. Zero valent iron (ZVI) was chosen as the primary electron donor in most experimental systems. Research proceeded in three phases and the key findings of each phase are reported here. Phase I examined Cr(VI) reduction and utilized micro- and nano-sized ZVI as the electron donors. Electron shuttle catalysts tested were cobalt- and iron-containing metalloporphyrins and Vitamin B12. To aid in the recycle and reuse of the nano-sized ZVI and soluble catalysts, sol-gels and calcium-alginate gel beads were tested as immobilization/support matrices. Although the nano-sized ZVI could be incorporated within the alginate gel beads, preliminary attempts to trap it in sol-gels were not

  20. Biogeochemical N signatures from rate-yield trade-offs during in vitro chemosynthetic NO3- reduction by deep-sea vent ε-Proteobacteria and Aquificae growing at different temperatures

    Science.gov (United States)

    Pérez-Rodríguez, Ileana; Sievert, Stefan M.; Fogel, Marilyn L.; Foustoukos, Dionysis I.

    2017-08-01

    NO3- reduction is a metabolism that is widespread among ε-Proteobacteria and Aquificae, two abundant classes of microorganisms found at deep-sea vents. In this study, we used Sulfurovum lithotrophicum, Caminibacter mediatlanticus and Thermovibrio ammonificans as representatives of these groups to study ecophysiological, metabolic and biogeochemical parameters associated with chemolithoautotrophic NO3- reduction under different temperature regimes. We observed that while S. lithotrophicum and C. mediatlanticus achieved higher cell densities than T. ammonificans, the overall NO3- consumption by the latter was on average ∼9 and ∼5 times faster on a per cell basis, respectively. Comparison with previously published data from other cultured vent ε-Proteobacteria and Aquificae suggests that the rate-yield trade-offs observed in our experiments are generally conserved between these two groups in line with their ecophysiologies. Kinetic isotope effects of N from NO3- reduction were 9.6 ± 2.7‰ for S. lithotrophicum, 6.4 ± 0.7‰ for C. mediatlanticus and 8.8 ± 0.6‰ for T. ammonificans. Our results help evaluate how metabolic partitioning between growth efficiency and reaction kinetics during chemolithoautotrophic NO3- reduction affect the concentration and isotope composition of N compounds at deep-sea hydrothermal vents.

  1. Tip vorticity reduction and optimization of lifting surfaces

    NARCIS (Netherlands)

    Sparenberg, JA

    2001-01-01

    In linearized optimization theory, lifting surfaces, moving in an inviscid and incompressible fluid, shed tip vorticity of which the strength has infinite square-root singularities. Here we discuss that an optimization procedure can be coupled to constraints so that the strength of the shed vorticit

  2. Finding optimal HBr reduction of inkjet printed graphene oxide for flexible electronics

    Energy Technology Data Exchange (ETDEWEB)

    Wlasny, I., E-mail: igor.wlasny@fuw.edu.pl [Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236, Lodz (Poland); Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02 093, Warsaw (Poland); Rogala, M.; Dabrowski, P.; Kowalczyk, P.J.; Busiakiewicz, A.; Kozlowski, W. [Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236, Lodz (Poland); Lipinska, L.; Jagiello, J.; Aksienionek, M. [Institute of Electronic Materials Technology, Wolczynska 133, 01-919, Warsaw (Poland); Sieradzki, Z. [Electrotechnological Company QWERTY Ltd., Siewna 21, 94-250, Lodz (Poland); Krucinska, I.; Puchalski, M.; Skrzetuska, E.; Draczynski, Z. [Department of Material and Commodity Sciences and Textile Metrology, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz (Poland); Klusek, Z. [Department of Solid State Physics, Faculty of Physics and Applied Informatics, University of Lodz, Pomorska 149/153, 90-236, Lodz (Poland)

    2016-09-15

    In this article we present the results of our investigations of reduction of graphene oxide overprints, deposited by ink-jet method, by hydrobromic acid. Our study presents impact of different parameters of reduction, such as a temperature and time of the process on the chemical composition and electrical conductivity of the resulting material – reduced graphene oxide. Our results show the outstanding potential of this method for use in the production of flexible and elastic electronics and indicate the optimal parameters of reduction, which allow producing the optimal product. - Highlights: • The process of reduction of graphene oxide inkjet printouts by HBr is investigated. • Impact of parameters of reduction on the chemical structure of printout is studied. • Impact of parameters of reduction on the sheet resistance of printout is studied. • Optimal parameters of reduction are proposed.

  3. An attempt of reduction of optimization costs of complex industrial processes

    Science.gov (United States)

    Sztangret, Łukasz; Kusiak, Jan

    2017-09-01

    Reduction of computational costs of optimization of real industrial processes is crucial, because the models of these processes are often complex and demand time consuming numerical computations. Iterative optimization procedures have to run the simulations many times and therefore the computational costs of the optimization may be unacceptable high. This is why a new optimization methods and strategies which need less simulation runs are searched. The paper is focused on the problem of reduction of computational costs of optimization procedure. The main goal is the presentation of developed by the Authors new, efficient Approximation Based Optimization (ABO) and Modified Approximation Based Optimization (MABO) methods which allow finding the global minimum in smaller number of objective function calls. Detailed algorithm of the MABO method as well as the results of tests using several benchmark functions are presented. The efficiency of MABO method was compared with heuristic methods and the results show that MABO method reduces the computational costs and improve the optimization accuracy.

  4. Selenate reduction to elemental selenium by anaerobic bacteria in sediments and culture: biogeochemical significance of a novel, sulfate-independent respiration

    Science.gov (United States)

    Oremland, Ronald S.; Hollibaugh, James T.; Maest, Ann S.; Presser, Theresa S.; Miller, Laurence G.; Culbertson, Charles W.

    1989-01-01

    Interstitial water profiles of SeO42−, SeO32−, SO42−, and Cl− in anoxic sediments indicated removal of the seleno-oxyanions by a near-surface process unrelated to sulfate reduction. In sediment slurry experiments, a complete reductive removal of SeO42− occurred under anaerobic conditions, was more rapid with H2 or acetate, and was inhibited by O2, NO3−, MnO2, or autoclaving but not by SO42− or FeOOH. Oxidation of acetate in sediments could be coupled to selenate but not to molybdate. Reduction of selenate to elemental selenium was determined to be the mechanism for loss from solution. Selenate reduction was inhibited by tungstate and chromate but not by molybdate. A small quantity of the elemental selenium precipitated into sediments from solution could be resolublized by oxidation with either nitrate or FeOOH, but not with MnO2. A bacterium isolated from estuarine sediments demonstrated selenate-dependent growth on acetate, forming elemental selenium and carbon dioxide as respiratory end products. These results indicate that dissimilatory selenate reduction to elemental selenium is the major sink for selenium oxyanions in anoxic sediments. In addition, they suggest application as a treatment process for removing selenium oxyanions from wastewaters and also offer an explanation for the presence of selenite in oxic waters.

  5. Optimal periodic disturbance reduction for active noise cancelation

    Science.gov (United States)

    Kinney, C. E.; de Callafon, R. A.; Dunens, E.; Bargerhuff, R.; Bash, C. E.

    2007-08-01

    The design of an optimal internal model-based (IMB) controller by extending standard discrete time optimal control theory for IMB controllers is described. The optimal observer and state feedback gains of the IMB controller are given via the solution of discrete time algebraic Riccati equations. The design method is applied to an acoustic system that is subjected to disturbances from a server fan. Periodic disturbances from the server fan appear as harmonics of the fundamental frequency of the fan. Parametric models for the plant and non-periodic part of the disturbance are identified from experimental data. An internal model is designed in discrete time and the internal model principle is used to design a feedback controller that rejects periodic disturbances in the acoustic system. The controller is implemented in real-time and successfully attenuates the first four harmonics of the fan noise.

  6. Optimal Tax Reduction by Depreciation : A Stochastic Model

    OpenAIRE

    Berg, M; De Waegenaere, A.M.B.; Wielhouwer, J.L.

    1996-01-01

    This paper focuses on the choice of a depreciation method, when trying to minimize the expected value of the present value of future tax payments.In a quite general model that allows for stochastic future cash- ows and a tax structure with tax brackets, we determine the optimal choice between the straight line depreciation method and a speci c accelerated depreciation method. We show how the distributions of the cash- ows, the discount rate, and the tax structure can in uence the optimal deci...

  7. Optimal reconfiguration-based dynamic tariff for congestion management and line loss reduction in distribution networks

    DEFF Research Database (Denmark)

    Huang, Shaojun; Wu, Qiuwei; Cheng, Lin

    2016-01-01

    This paper presents an optimal reconfiguration-based dynamic tariff (DT) method for congestion management and line loss reduction in distribution networks with high penetration of electric vehicles. In the proposed DT concept, feeder reconfiguration (FR) is employed through mixed integer programm......This paper presents an optimal reconfiguration-based dynamic tariff (DT) method for congestion management and line loss reduction in distribution networks with high penetration of electric vehicles. In the proposed DT concept, feeder reconfiguration (FR) is employed through mixed integer...... manner through the DT framework. Three case studies were conducted to validate the optimal reconfiguration-based DT method for congestion management and line loss reduction in distribution networks....

  8. Noise Reduction with Optimal Variable Span Linear Filters

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Benesty, Jacob; Christensen, Mads Græsbøll

    2016-01-01

    of eigenvectors stemming from a joint diagonalization of the covariance matrices of the signal of interest and the noise. The resulting filters are flexible in that it is possible to trade off distortion of the desired signal for improved noise reduction. This tradeoff is controlled by the number of eigenvectors...

  9. Reduction of initial stress stiffening by topology optimization

    DEFF Research Database (Denmark)

    Philippine, M. A.; Sigmund, Ole; Rebeiz, G. M.

    2012-01-01

    Topology optimization is a rigorous method of obtaining non-intuitive designs. We use it to obtain a capacitive RF switch that stiffens little in response to an increase of the in-plane biaxial stresses that typically develop during MEMS fabrication. The actuation voltage is closely related...

  10. Optimal Tax Reduction by Depreciation : A Stochastic Model

    NARCIS (Netherlands)

    Berg, M.; De Waegenaere, A.M.B.; Wielhouwer, J.L.

    1996-01-01

    This paper focuses on the choice of a depreciation method, when trying to minimize the expected value of the present value of future tax payments.In a quite general model that allows for stochastic future cash- ows and a tax structure with tax brackets, we determine the optimal choice between the st

  11. Optimal Tax Reduction by Depreciation : A Stochastic Model

    NARCIS (Netherlands)

    Berg, M.; De Waegenaere, A.M.B.; Wielhouwer, J.L.

    1996-01-01

    This paper focuses on the choice of a depreciation method, when trying to minimize the expected value of the present value of future tax payments.In a quite general model that allows for stochastic future cash- ows and a tax structure with tax brackets, we determine the optimal choice between the

  12. Bayesian Optimal Auctions via Multi- to Single-agent Reduction

    Science.gov (United States)

    2012-03-23

    reduced form auctions: A geometric approach. Econo- metrica , 59(4):pp. 1175–1187. Briest, P., Chawla, S., Kleinberg, R., and Weinberg, S. M. (2010...multidimensional screening. Econo- metrica , 66(4):783–826. Schrijver, A. (2003). Combinatorial Optimization : Polyhedra and Efficiency (Algorithms and

  13. Test Cases Reduction and Selection Optimization in Testing Web Services

    Directory of Open Access Journals (Sweden)

    Izzat Alsmadi

    2012-10-01

    Full Text Available Software testing in web services environment faces different challenges in comparison with testing in traditional software environments. Regression testing activities are triggered based on software changes or evolutions. In web services, evolution is not a choice for service clients. They have always to use the current updated version of the software. In addition test execution or invocation is expensive in web services and hence providing algorithms to optimize test case generation and execution is vital. In this environment, we proposed several approach for test cases’ selection in web services’ regression testing. Testing in this new environment should evolve to be included part of the service contract. Service providers should provide data or usage sessions that can help service clients reduce testing expenses through optimizing the selected and executed test cases.

  14. Variable-fidelity optimization with design space reduction

    Institute of Scientific and Technical Information of China (English)

    Mohammad Kashif Zahir; Gao Zhenghong

    2013-01-01

    Advanced engineering systems,like aircraft,are defined by tens or even hundreds of design variables.Building an accurate surrogate model for use in such high-dimensional optimization problems is a difficult task owing to the curse of dimensionality.This paper presents a new algorithm to reduce the size of a design space to a smaller region of interest allowing a more accurate surrogate model to be generated.The framework requires a set of models of different physical or numerical fidelities.The low-fidelity (LF) model provides physics-based approximation of the high-fidelity (HF) model at a fraction of the computational cost.It is also instrumental in identifying the small region of interest in the design space that encloses the high-fidelity optimum.A surrogate model is then constructed to match the low-fidelity model to the high-fidelity model in the identified region of interest.The optimization process is managed by an update strategy to prevent convergence to false optima.The algorithm is applied on mathematical problems and a two-dimensional aerodynamic shape optimization problem in a variable-fidelity context.Results obtained are in excellent agreement with high-fidelity results,even with lower-fidelity flow solvers,while showing up to 39% time savings.

  15. Cuckoo Search Optimization for Reduction of a Greenhouse Climate Model

    Directory of Open Access Journals (Sweden)

    Hasni Abdelhafid

    2016-07-01

    Full Text Available Greenhouse climate and crop models and specially reduced models are necessary for bettering environmental management and control ability. In this paper, we present a new metaheuristic method, called Cuckoo Search (CS algorithm, established on the life of a bird family for selecting the parameters of a reduced model which optimizes their choice by minimizing a cost function. The reduced model was already developed for control purposes and published in the literature. The proposed models target at simulating and predicting the greenhouse environment. [?]. This study focuses on the dynamical behaviors of the inside air temperature and pressure using ventilation. Some experimental results are used for model validation, the greenhouse being automated with actuators and sensors connected to a greenhouse control system on the cuckoo search methods to determine the best set of parameters allowing for the convergence of a criteria based on the difference between calculated and observed state variables (inside air temperature and water vapour pressure content. The results shown that the tested Cuckoo Search algorithm allows for a faster convergence towards the optimal solution than classical optimization methods.

  16. Optimization of dental CBCT exposures through mAs reduction.

    Science.gov (United States)

    Pauwels, R; Seynaeve, L; Henriques, J C G; de Oliveira-Santos, C; Souza, P C; Westphalen, F H; Rubira-Bullen, I R F; Ribeiro-Rotta, R F; Rockenbach, M I B; Haiter-Neto, F; Pittayapat, P; Bosmans, H; Bogaerts, R; Jacobs, R

    2015-01-01

    To investigate the effect of tube current-exposure time (mAs) reduction on clinical and technical image quality for different CBCT scanners, and to determine preliminary minimally acceptable values for the mAs and contrast-to-noise ratio (CNR) in CBCT. A polymethyl methacrylate (PMMA) phantom and an anthropomorphic skull phantom, containing a human skeleton embedded in polyurethane, were scanned using four CBCT devices, including seven exposure protocols. For all protocols, the mAs was varied within the selectable range. Using the PMMA phantom, the CNRAIR was measured and corrected for voxel size. Eight axial slices and one coronal slice showing various anatomical landmarks were selected for each CBCT scan of the skull phantom. The slices were presented to six dentomaxillofacial radiologists, providing scores for various anatomical and diagnostic parameters. A hyperbolic relationship was seen between CNRAIR and mAs. Similarly, a gradual reduction in clinical image quality was seen at lower mAs values; however, for several protocols, image quality remained acceptable for a moderate or large mAs reduction compared with the standard exposure setting, depending on the clinical application. The relationship between mAs, CNRAIR and observer scores was different for each CBCT device. Minimally acceptable values for mAs were between 9 and 70, depending on the criterion and clinical application. Although noise increased at a lower mAs, clinical image quality often remained acceptable at exposure levels below the manufacturer's recommended setting, for certain patient groups. Currently, it is not possible to determine minimally acceptable values for image quality that are applicable to multiple CBCT models.

  17. Heliostat field cost reduction by `slope drive' optimization

    Science.gov (United States)

    Arbes, Florian; Weinrebe, Gerhard; Wöhrbach, Markus

    2016-05-01

    An algorithm to optimize power tower heliostat fields employing heliostats with so-called slope drives is presented. It is shown that a field using heliostats with the slope drive axes configuration has the same performance as a field with conventional azimuth-elevation tracking heliostats. Even though heliostats with the slope drive configuration have a limited tracking range, field groups of heliostats with different axes or different drives are not needed for different positions in the heliostat field. The impacts of selected parameters on a benchmark power plant (PS10 near Seville, Spain) are analyzed.

  18. Optimal State-Space Reduction for Pedigree Hidden Markov Models

    CERN Document Server

    Kirkpatrick, Bonnie

    2012-01-01

    To analyze whole-genome genetic data inherited in families, the likelihood is typically obtained from a Hidden Markov Model (HMM) having a state space of 2^n hidden states where n is the number of meioses or edges in the pedigree. There have been several attempts to speed up this calculation by reducing the state-space of the HMM. One of these methods has been automated in a calculation that is more efficient than the naive HMM calculation; however, that method treats a special case and the efficiency gain is available for only those rare pedigrees containing long chains of single-child lineages. The other existing state-space reduction method treats the general case, but the existing algorithm has super-exponential running time. We present three formulations of the state-space reduction problem, two dealing with groups and one with partitions. One of these problems, the maximum isometry group problem was discussed in detail by Browning and Browning. We show that for pedigrees, all three of these problems hav...

  19. Frequency-temperature sensitivity reduction with optimized microwave Bragg resonators

    Science.gov (United States)

    Le Floch, J.-M.; Murphy, C.; Hartnett, J. G.; Madrangeas, V.; Krupka, J.; Cros, D.; Tobar, M. E.

    2017-01-01

    Dielectric resonators are employed to build state-of-the-art low-noise and high-stability oscillators operating at room and cryogenic temperatures. A resonator temperature coefficient of frequency is one criterion of performance. This paper reports on predictions and measurements of this temperature coefficient of frequency for three types of cylindrically symmetric Bragg resonators operated at microwave frequencies. At room temperature, microwave Bragg resonators have the best potential to reach extremely high Q-factors. Research has been conducted over the last decade on modeling, optimizing, and realizing such high Q-factor devices for applications such as filtering, sensing, and frequency metrology. We present an optimized design, which has a temperature sensitivity 2 to 4 times less than current whispering gallery mode resonators without using temperature compensating techniques and about 30% less than other existing Bragg resonators. Also, the performance of a new generation single-layered Bragg resonator, based on a hybrid-Bragg-mode, is reported with a sensitivity of about -12 ppm/K at 295 K. For a single reflector resonator, it achieves a similar level of performance as a double-Bragg-reflector resonator but with a more compact structure and performs six times better than whispering-gallery-mode resonators. The hybrid resonator promises to deliver a new generation of high-sensitivity sensors and high-stability room-temperature oscillators.

  20. Optimization of magnetite carrier precipitation process for transuranic waste reduction

    Energy Technology Data Exchange (ETDEWEB)

    Slater, S.A.; Chamberlain, D.B.; Aase, S.A.; Babcock, B.D.; Conner, C.; Sedlet, J.; Vandegrift, G.F. [Argonne National Lab., IL (United States). Chemical Technology Div.

    1995-12-31

    Transuranic (TRU) waste that is being generated at Argonne National Laboratory has a TRU activity ranging from 10{sup 2} to 10{sup 7} nCi/g with a wide variety of chemical compositions. Currently, the waste is stored in highly acidic solutions that must be neutralized for intermediate storage. A magnetite carrier precipitation process has been adapted to concentrate TRU isotopes in a noncorrosive solid phase. In this paper, the authors report the results of a series of laboratory tests done to optimize the process. The parameters they optimized included (1) magnetite concentration used to precipitate the TRUs from solution, (2) formation of magnetite (in situ or ex situ), (3) processing pH, and (4) temperature and mixing time of the carrier precipitation. They also studied the effects of anions, cations, and complexing agents in the waste solutions on the carrier precipitation and the effect of magnetite solids loading on the filtration equipment. An overview is given of the planned full-scale process, which will be operated in a glovebox.

  1. Optimization of helicopter airframe structures for vibration reduction considerations, formulations and applications

    Science.gov (United States)

    Murthy, T. Sreekanta

    1988-01-01

    Several key issues involved in the application of formal optimization technique to helicopter airframe structures for vibration reduction are addressed. Considerations which are important in the optimization of real airframe structures are discussed. Considerations necessary to establish relevant set of design variables, constraints and objectives which are appropriate to conceptual, preliminary, detailed design, ground and flight test phases of airframe design are discussed. A methodology is suggested for optimization of airframes in various phases of design. Optimization formulations that are unique to helicopter airframes are described and expressions for vibration related functions are derived. Using a recently developed computer code, the optimization of a Bell AH-1G helicopter airframe is demonstrated.

  2. New Search Space Reduction Algorithm for Vertical Reference Trajectory Optimization

    Directory of Open Access Journals (Sweden)

    Alejandro MURRIETA-MENDOZA

    2016-06-01

    Full Text Available Burning the fuel required to sustain a given flight releases pollution such as carbon dioxide and nitrogen oxides, and the amount of fuel consumed is also a significant expense for airlines. It is desirable to reduce fuel consumption to reduce both pollution and flight costs. To increase fuel savings in a given flight, one option is to compute the most economical vertical reference trajectory (or flight plan. A deterministic algorithm was developed using a numerical aircraft performance model to determine the most economical vertical flight profile considering take-off weight, flight distance, step climb and weather conditions. This algorithm is based on linear interpolations of the performance model using the Lagrange interpolation method. The algorithm downloads the latest available forecast from Environment Canada according to the departure date and flight coordinates, and calculates the optimal trajectory taking into account the effects of wind and temperature. Techniques to avoid unnecessary calculations are implemented to reduce the computation time. The costs of the reference trajectories proposed by the algorithm are compared with the costs of the reference trajectories proposed by a commercial flight management system using the fuel consumption estimated by the FlightSim® simulator made by Presagis®.

  3. Lidar arc scan uncertainty reduction through scanning geometry optimization

    Directory of Open Access Journals (Sweden)

    H. Wang

    2015-10-01

    Full Text Available Doppler lidars are frequently operated in a mode referred to as arc scans, wherein the lidar beam scans across a sector with a fixed elevation angle and the resulting measurements are used to derive an estimate of the n minute horizontal mean wind velocity (speed and direction. Previous studies have shown that the uncertainty in the measured wind speed originates from turbulent wind fluctuations and depends on the scan geometry (the arc span and the arc orientation. This paper is designed to provide guidance on optimal scan geometries for two key applications in the wind energy industry: wind turbine power performance analysis and annual energy production. We present a quantitative analysis of the retrieved wind speed uncertainty derived using a theoretical model with the assumption of isotropic and frozen turbulence, and observations from three sites that are onshore with flat terrain, onshore with complex terrain and offshore, respectively. The results from both the theoretical model and observations show that the uncertainty is scaled with the turbulence intensity such that the relative standard error on the 10 min mean wind speed is about 30 % of the turbulence intensity. The uncertainty in both retrieved wind speeds and derived wind energy production estimates can be reduced by aligning lidar beams with the dominant wind direction, increasing the arc span and lowering the number of beams per arc scan. Large arc spans should be used at sites with high turbulence intensity and/or large wind direction variation when arc scans are used for wind resource assessment.

  4. Perceptually optimized gain function for cochlear implant signal-to-noise ratio based noise reduction.

    Science.gov (United States)

    Mauger, Stefan J; Dawson, Pam W; Hersbach, Adam A

    2012-01-01

    Noise reduction in cochlear implants has achieved significant speech perception improvements through spectral subtraction and signal-to-noise ratio based noise reduction techniques. Current methods use gain functions derived through mathematical optimization or motivated by normal listening psychoacoustic experiments. Although these gain functions have been able to improve speech perception, recent studies have indicated that they are not optimal for cochlear implant noise reduction. This study systematically investigates cochlear implant recipients' speech perception and listening preference of noise reduction with a range of gain functions. Results suggest an advantageous gain function and show that gain functions currently used for noise reduction are not optimal for cochlear implant recipients. Using the cochlear implant optimised gain function, a 27% improvement over the current advanced combination encoder (ACE) stimulation strategy in speech weighted noise and a 7% improvement over current noise reduction strategies were observed in babble noise conditions. The optimized gain function was also most preferred by cochlear implant recipients. The CI specific gain function derived from this study can be easily incorporated into existing noise reduction strategies, to further improve listening performance for CI recipients in challenging environments.

  5. Spatially distributed control for optimal drag reduction of the flow past a circular cylinder

    Science.gov (United States)

    Poncet, Philippe; Hildebrand, Roland; Cottet, Georges-Henri; Koumoutsakos, Petros

    We report high drag reduction in direct numerical simulations of controlled flows past circular cylinders at Reynolds numbers of 300 and 1000. The flow is controlled by the azimuthal component of the tangential velocity of the cylinder surface. Starting from a spanwise-uniform velocity profile that leads to high drag reduction, the optimization procedure identifies, for the same energy input, spanwise-varying velocity profiles that lead to higher drag reduction. The three-dimensional variations of the velocity field, corresponding to modes A and B of three-dimensional wake instabilities, are largely responsible for this drag reduction. The spanwise wall velocity variations introduce streamwise vortex braids in the wake that are responsible for reducing the drag induced by the primary spanwise vortices shed by the cylinder. The results demonstrate that extending two-dimensional controllers to three-dimensional flows is not optimal as three-dimensional control strategies can lead efficiently to higher drag reduction.

  6. Dose reduction and optimization studies (ALARA) at nuclear power facilities. [PWR; BWR

    Energy Technology Data Exchange (ETDEWEB)

    Baum, J.W.; Meinhold, C.B.

    1983-01-01

    Brookhaven National Laboratory (BNL) has been commissioned by the Nuclear Regulatory Commission (NRC) to study dose-reduction techniques and effectiveness of as low as reasonably achievable (ALARA) planning at LWR plants. These studies have the following objectives: identify high-dose maintenance tasks; identify dose-reduction techniques; examine incentives for dose reduction; evaluate cost-effectiveness and optimization of dose-reduction techniques; and compile an ALARA handbook on data, engineering modifications, cost-effectiveness calculations, and other information of interest to ALARA practioners.

  7. Mechanistic site-based emulation of a global ocean biogeochemical model (MEDUSA 1.0 for parametric analysis and calibration: an application of the Marine Model Optimization Testbed (MarMOT 1.1

    Directory of Open Access Journals (Sweden)

    J. C. P. Hemmings

    2015-03-01

    Full Text Available Biogeochemical ocean circulation models used to investigate the role of plankton ecosystems in global change rely on adjustable parameters to capture the dominant biogeochemical dynamics of a complex biological system. In principle, optimal parameter values can be estimated by fitting models to observational data, including satellite ocean colour products such as chlorophyll that achieve good spatial and temporal coverage of the surface ocean. However, comprehensive parametric analyses require large ensemble experiments that are computationally infeasible with global 3-D simulations. Site-based simulations provide an efficient alternative but can only be used to make reliable inferences about global model performance if robust quantitative descriptions of their relationships with the corresponding 3-D simulations can be established. The feasibility of establishing such a relationship is investigated for an intermediate complexity biogeochemistry model (MEDUSA coupled with a widely used global ocean model (NEMO. A site-based mechanistic emulator is constructed for surface chlorophyll output from this target model as a function of model parameters. The emulator comprises an array of 1-D simulators and a statistical quantification of the uncertainty in their predictions. The unknown parameter-dependent biogeochemical environment, in terms of initial tracer concentrations and lateral flux information required by the simulators, is a significant source of uncertainty. It is approximated by a mean environment derived from a small ensemble of 3-D simulations representing variability of the target model behaviour over the parameter space of interest. The performance of two alternative uncertainty quantification schemes is examined: a direct method based on comparisons between simulator output and a sample of known target model "truths" and an indirect method that is only partially reliant on knowledge of the target model output. In general, chlorophyll

  8. Aerodynamic Drag Reduction for a Generic Truck Using Geometrically Optimized Rear Cabin Bumps

    Directory of Open Access Journals (Sweden)

    Abdellah Ait Moussa

    2015-01-01

    Full Text Available The continuous surge in gas prices has raised major concerns about vehicle fuel efficiency, and drag reduction devices offer a promising strategy. In this paper, we investigate the mechanisms by which geometrically optimized bumps, placed on the rear end of the cabin roof of a generic truck, reduce aerodynamic drag. The incorporation of these devices requires proper choices of the size, location, and overall geometry. In the following analysis we identify these factors using a novel methodology. The numerical technique combines automatic modeling of the add-ons, computational fluid dynamics and optimization using orthogonal arrays, and probabilistic restarts. Numerical results showed reduction in aerodynamic drag between 6% and 10%.

  9. Collaborative Emission Reduction Model Based on Multi-Objective Optimization for Greenhouse Gases and Air Pollutants.

    Directory of Open Access Journals (Sweden)

    Qing-chun Meng

    Full Text Available CO2 emission influences not only global climate change but also international economic and political situations. Thus, reducing the emission of CO2, a major greenhouse gas, has become a major issue in China and around the world as regards preserving the environmental ecology. Energy consumption from coal, oil, and natural gas is primarily responsible for the production of greenhouse gases and air pollutants such as SO2 and NOX, which are the main air pollutants in China. In this study, a mathematical multi-objective optimization method was adopted to analyze the collaborative emission reduction of three kinds of gases on the basis of their common restraints in different ways of energy consumption to develop an economic, clean, and efficient scheme for energy distribution. The first part introduces the background research, the collaborative emission reduction for three kinds of gases, the multi-objective optimization, the main mathematical modeling, and the optimization method. The second part discusses the four mathematical tools utilized in this study, which include the Granger causality test to analyze the causality between air quality and pollutant emission, a function analysis to determine the quantitative relation between energy consumption and pollutant emission, a multi-objective optimization to set up the collaborative optimization model that considers energy consumption, and an optimality condition analysis for the multi-objective optimization model to design the optimal-pole algorithm and obtain an efficient collaborative reduction scheme. In the empirical analysis, the data of pollutant emission and final consumption of energies of Tianjin in 1996-2012 was employed to verify the effectiveness of the model and analyze the efficient solution and the corresponding dominant set. In the last part, several suggestions for collaborative reduction are recommended and the drawn conclusions are stated.

  10. Collaborative Emission Reduction Model Based on Multi-Objective Optimization for Greenhouse Gases and Air Pollutants.

    Science.gov (United States)

    Meng, Qing-chun; Rong, Xiao-xia; Zhang, Yi-min; Wan, Xiao-le; Liu, Yuan-yuan; Wang, Yu-zhi

    2016-01-01

    CO2 emission influences not only global climate change but also international economic and political situations. Thus, reducing the emission of CO2, a major greenhouse gas, has become a major issue in China and around the world as regards preserving the environmental ecology. Energy consumption from coal, oil, and natural gas is primarily responsible for the production of greenhouse gases and air pollutants such as SO2 and NOX, which are the main air pollutants in China. In this study, a mathematical multi-objective optimization method was adopted to analyze the collaborative emission reduction of three kinds of gases on the basis of their common restraints in different ways of energy consumption to develop an economic, clean, and efficient scheme for energy distribution. The first part introduces the background research, the collaborative emission reduction for three kinds of gases, the multi-objective optimization, the main mathematical modeling, and the optimization method. The second part discusses the four mathematical tools utilized in this study, which include the Granger causality test to analyze the causality between air quality and pollutant emission, a function analysis to determine the quantitative relation between energy consumption and pollutant emission, a multi-objective optimization to set up the collaborative optimization model that considers energy consumption, and an optimality condition analysis for the multi-objective optimization model to design the optimal-pole algorithm and obtain an efficient collaborative reduction scheme. In the empirical analysis, the data of pollutant emission and final consumption of energies of Tianjin in 1996-2012 was employed to verify the effectiveness of the model and analyze the efficient solution and the corresponding dominant set. In the last part, several suggestions for collaborative reduction are recommended and the drawn conclusions are stated.

  11. Finite element model reduction application to parametric studies and optimization of rotorcraft structures

    Science.gov (United States)

    Hashemi-Kia, M.; Toossi, M.

    1990-01-01

    As a result of this work, a reduction procedure has been developed which can be applied to large finite element model of airframe type structures. This procedure, which is tailored to be used with MSC/NASTRAN finite element code, is applied to the full airframe dynamic finite element model of AH-64A Attack Helicopter. The applicability of the resulting reduced model to parametric and optimization studies is examined. Through application of the design sensitivity analysis, the viability and efficiency of this reduction technique has been demonstrated in a vibration reduction study.

  12. Optimization Solutions for Improving the Performance of the Parallel Reduction Algorithm Using Graphics Processing Units

    Directory of Open Access Journals (Sweden)

    Ion LUNGU

    2012-01-01

    Full Text Available In this paper, we research, analyze and develop optimization solutions for the parallel reduction function using graphics processing units (GPUs that implement the Compute Unified Device Architecture (CUDA, a modern and novel approach for improving the software performance of data processing applications and algorithms. Many of these applications and algorithms make use of the reduction function in their computational steps. After having designed the function and its algorithmic steps in CUDA, we have progressively developed and implemented optimization solutions for the reduction function. In order to confirm, test and evaluate the solutions' efficiency, we have developed a custom tailored benchmark suite. We have analyzed the obtained experimental results regarding: the comparison of the execution time and bandwidth when using graphic processing units covering the main CUDA architectures (Tesla GT200, Fermi GF100, Kepler GK104 and a central processing unit; the data type influence; the binary operator's influence.

  13. A Multi-Model Reduction Technique for Optimization of Coupled Structural-Acoustic Problems

    DEFF Research Database (Denmark)

    Creixell Mediante, Ester; Jensen, Jakob Søndergaard; Brunskog, Jonas;

    2016-01-01

    Finite Element models of structural-acoustic coupled systems can become very large for complex structures with multiple connected parts. Optimization of the performance of the structure based on harmonic analysis of the system requires solving the coupled problem iteratively and for several...... frequencies, which can become highly time consuming. Several modal-based model reduction techniques for structure-acoustic interaction problems have been developed in the literature. The unsymmetric nature of the pressure-displacement formulation of the problem poses the question of how the reduction modal...... base should be formed, given that the modal vectors are not orthogonal due to the asymmetry of the system matrices. In this paper, a multi-model reduction (MMR) technique for structure-acoustic interaction problems is developed. In MMR, the reduction base is formed with the modal vectors of a family...

  14. Optimal dipole-field profiles for emittance reduction in storage rings

    Directory of Open Access Journals (Sweden)

    Chun-xi Wang

    2011-03-01

    Full Text Available In recent years nonuniform dipoles with bending-radius variation have been studied for reducing storage ring emittance. According to a new minimum-emittance theory, the effects of an arbitrary dipole can be characterized with two parameters determined by the dipole. To have a better idea of the potentials of nonuniform dipoles, here we numerically explore the possible values of these two parameters and associated bending profiles for optimal emittance reduction. Such optimization results provide a useful reference for lattice designs involving nonuniform bending. Simple bending-radius profiles (a short segment of constant radius with linear ramps on the sides were found to be close to the optimal. Basic beam and lattice properties such as emittance, energy spread, and phase advances are presented based on the optimal dipole solutions.

  15. Linear adaptive noise-reduction filters for tomographic imaging: Optimizing for minimum mean square error

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Winston Y. [Univ. of California, Berkeley, CA (United States)

    1993-04-01

    This thesis solves the problem of finding the optimal linear noise-reduction filter for linear tomographic image reconstruction. The optimization is data dependent and results in minimizing the mean-square error of the reconstructed image. The error is defined as the difference between the result and the best possible reconstruction. Applications for the optimal filter include reconstructions of positron emission tomographic (PET), X-ray computed tomographic, single-photon emission tomographic, and nuclear magnetic resonance imaging. Using high resolution PET as an example, the optimal filter is derived and presented for the convolution backprojection, Moore-Penrose pseudoinverse, and the natural-pixel basis set reconstruction methods. Simulations and experimental results are presented for the convolution backprojection method.

  16. Parameter uncertainty-based pattern identification and optimization for robust decision making on watershed load reduction

    Science.gov (United States)

    Jiang, Qingsong; Su, Han; Liu, Yong; Zou, Rui; Ye, Rui; Guo, Huaicheng

    2017-04-01

    Nutrients loading reduction in watershed is essential for lake restoration from eutrophication. The efficient and optimal decision-making on loading reduction is generally based on water quality modeling and the quantitative identification of nutrient sources at the watershed scale. The modeling process is influenced inevitably by inherent uncertainties, especially by uncertain parameters due to equifinality. Therefore, the emerging question is: if there is parameter uncertainty, how to ensure the robustness of the optimal decisions? Based on simulation-optimization models, an integrated approach of pattern identification and analysis of robustness was proposed in this study that focuses on the impact of parameter uncertainty in water quality modeling. Here the pattern represents the discernable regularity of solutions for load reduction under multiple parameter sets. Pattern identification is achieved by using a hybrid clustering analysis (i.e., Ward-Hierarchical and K-means), which was flexible and efficient in analyzing Lake Bali near the Yangtze River in China. The results demonstrated that urban domestic nutrient load is the most potential source that should be reduced, and there are two patterns for Total Nitrogen (TN) reduction and three patterns for Total Phosphorus (TP) reduction. The patterns indicated different total reduction of nutrient loads, which reflect diverse decision preferences. The robust solution was identified by the highest accomplishment with the water quality at monitoring stations that were improved uniformly with this solution. We conducted a process analysis of robust decision-making that was based on pattern identification and uncertainty, which provides effective support for decision-making with preference under uncertainty.

  17. A Hybrid Optimization Framework with POD-based Order Reduction and Design-Space Evolution Scheme

    Science.gov (United States)

    Ghoman, Satyajit S.

    The main objective of this research is to develop an innovative multi-fidelity multi-disciplinary design, analysis and optimization suite that integrates certain solution generation codes and newly developed innovative tools to improve the overall optimization process. The research performed herein is divided into two parts: (1) the development of an MDAO framework by integration of variable fidelity physics-based computational codes, and (2) enhancements to such a framework by incorporating innovative features extending its robustness. The first part of this dissertation describes the development of a conceptual Multi-Fidelity Multi-Strategy and Multi-Disciplinary Design Optimization Environment (M3 DOE), in context of aircraft wing optimization. M 3 DOE provides the user a capability to optimize configurations with a choice of (i) the level of fidelity desired, (ii) the use of a single-step or multi-step optimization strategy, and (iii) combination of a series of structural and aerodynamic analyses. The modularity of M3 DOE allows it to be a part of other inclusive optimization frameworks. The M 3 DOE is demonstrated within the context of shape and sizing optimization of the wing of a Generic Business Jet aircraft. Two different optimization objectives, viz. dry weight minimization, and cruise range maximization are studied by conducting one low-fidelity and two high-fidelity optimization runs to demonstrate the application scope of M3 DOE. The second part of this dissertation describes the development of an innovative hybrid optimization framework that extends the robustness of M 3 DOE by employing a proper orthogonal decomposition-based design-space order reduction scheme combined with the evolutionary algorithm technique. The POD method of extracting dominant modes from an ensemble of candidate configurations is used for the design-space order reduction. The snapshot of candidate population is updated iteratively using evolutionary algorithm technique of

  18. Feedbacks between hydrological heterogeneity and bioremediation induced biogeochemical transformations

    Energy Technology Data Exchange (ETDEWEB)

    Englert, A.; Hubbard, S.S.; Williams, K.H.; Li, L.; Steefel, C.I.

    2009-04-15

    For guiding optimal design and interpretation of in-situ treatments that strongly perturb subsurface systems, knowledge about the spatial and temporal patterns of mass transport and reaction intensities are important. Here, a procedure was developed and applied to time-lapse concentrations of a conservative tracer (bromide), an injected amendment (acetate) and reactive species (iron(II), uranium(VI) and sulfate) associated with two field scale biostimulation experiments, which were conducted successively at the same field location over two years. The procedure is based on a temporal moment analysis approach that relies on a streamtube approximation. The study shows that biostimulated reactions can be considerably influenced by subsurface hydrological and geochemical heterogeneities: the delivery of bromide and acetate and the intensity of the sulfate reduction is interpreted to be predominantly driven by the hydrological heterogeneity, while the intensity of the iron reduction is interpreted to be primarily controlled by the geochemical heterogeneity. The intensity of the uranium(VI) reduction appears to be impacted by both the hydrological and geochemical heterogeneity. Finally, the study documents the existence of feedbacks between hydrological heterogeneity and remediation-induced biogeochemical transformations at the field scale, particularly the development of precipitates that may cause clogging and flow rerouting.

  19. Improving multi-objective reservoir operation optimization with sensitivity-informed dimension reduction

    Science.gov (United States)

    Chu, J.; Zhang, C.; Fu, G.; Li, Y.; Zhou, H.

    2015-08-01

    This study investigates the effectiveness of a sensitivity-informed method for multi-objective operation of reservoir systems, which uses global sensitivity analysis as a screening tool to reduce computational demands. Sobol's method is used to screen insensitive decision variables and guide the formulation of the optimization problems with a significantly reduced number of decision variables. This sensitivity-informed method dramatically reduces the computational demands required for attaining high-quality approximations of optimal trade-off relationships between conflicting design objectives. The search results obtained from the reduced complexity multi-objective reservoir operation problems are then used to pre-condition the full search of the original optimization problem. In two case studies, the Dahuofang reservoir and the inter-basin multi-reservoir system in Liaoning province, China, sensitivity analysis results show that reservoir performance is strongly controlled by a small proportion of decision variables. Sensitivity-informed dimension reduction and pre-conditioning are evaluated in their ability to improve the efficiency and effectiveness of multi-objective evolutionary optimization. Overall, this study illustrates the efficiency and effectiveness of the sensitivity-informed method and the use of global sensitivity analysis to inform dimension reduction of optimization problems when solving complex multi-objective reservoir operation problems.

  20. Ship Appearance Optimal Design on RCS Reduction Using Response Surface Method and Genetic Algorithms

    Institute of Scientific and Technical Information of China (English)

    YANG De-qing; GUO Feng-jun

    2008-01-01

    Radar cross section (RCS) reduction technologies are very important in survivability of the militarynaval vessels. Ship appearance shaping as an effective countermeasure of RCS reduction redirects the scatteredenergy from one angular region of interest in space to another region of little interest. To decrease the scatteringelectromagnetic signals from ship scientifically, optimization methods should be introduced in shaping design.Based on the assumption of the characteristic section design method, mathematical formulations for optimalshaping design were established. Because of the computation-intensive analysis and singularity in shapingoptimization, the response surface method (RSM) combined genetic algorithm (GA) was proposed. The poly-nomial response surface method was adopted in model approximation. Then genetic algorithms were employedto solve the surrogate optimization problem. By comparison RCS of the conventional and the optimal design,the superiority and effectiveness of proposed design methodology were verified.Ky words: radar cross section (RCS); characteristic section design method; response surface method; genetic algorithm (GA) was proposed. The polynomial response surface method was adopted in model approximation. Then genetic algorithms were employed to solve the surrogate optimization problem. By comparison RCS of the conventional and the optimal design, the superiority and effectiveness of proposed design methodology were verified.

  1. Stability Optimization of a Disc Brake System with Hybrid Uncertainties for Squeal Reduction

    Directory of Open Access Journals (Sweden)

    Hui Lü

    2016-01-01

    Full Text Available A hybrid uncertain model is introduced to deal with the uncertainties existing in a disc brake system in this paper. By the hybrid uncertain model, the uncertain parameters of the brake with enough sampling data are treated as probabilistic variables, while the uncertain parameters with limited data are treated as interval probabilistic variables whose distribution parameters are expressed as interval variables. Based on the hybrid uncertain model, the reliability-based design optimization (RBDO of a disc brake with hybrid uncertainties is proposed to explore the optimal design for squeal reduction. In the optimization, the surrogate model of the real part of domain unstable eigenvalue of the brake system is established, and the upper bound of its expectation is adopted as the optimization objective. The lower bounds of the functions related to system stability, the mass, and the stiffness of design component are adopted as the optimization constraints. The combinational algorithm of Genetic Algorithm and Monte-Carlo method is employed to perform the optimization. The results of a numerical example demonstrate the effectiveness of the proposed optimization on improving system stability and reducing squeal propensity of a disc brake under hybrid uncertainties.

  2. Pareto-optimal multi-objective dimensionality reduction deep auto-encoder for mammography classification.

    Science.gov (United States)

    Taghanaki, Saeid Asgari; Kawahara, Jeremy; Miles, Brandon; Hamarneh, Ghassan

    2017-07-01

    Feature reduction is an essential stage in computer aided breast cancer diagnosis systems. Multilayer neural networks can be trained to extract relevant features by encoding high-dimensional data into low-dimensional codes. Optimizing traditional auto-encoders works well only if the initial weights are close to a proper solution. They are also trained to only reduce the mean squared reconstruction error (MRE) between the encoder inputs and the decoder outputs, but do not address the classification error. The goal of the current work is to test the hypothesis that extending traditional auto-encoders (which only minimize reconstruction error) to multi-objective optimization for finding Pareto-optimal solutions provides more discriminative features that will improve classification performance when compared to single-objective and other multi-objective approaches (i.e. scalarized and sequential). In this paper, we introduce a novel multi-objective optimization of deep auto-encoder networks, in which the auto-encoder optimizes two objectives: MRE and mean classification error (MCE) for Pareto-optimal solutions, rather than just MRE. These two objectives are optimized simultaneously by a non-dominated sorting genetic algorithm. We tested our method on 949 X-ray mammograms categorized into 12 classes. The results show that the features identified by the proposed algorithm allow a classification accuracy of up to 98.45%, demonstrating favourable accuracy over the results of state-of-the-art methods reported in the literature. We conclude that adding the classification objective to the traditional auto-encoder objective and optimizing for finding Pareto-optimal solutions, using evolutionary multi-objective optimization, results in producing more discriminative features. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Computing Finite-Time Lyapunov Exponents with Optimally Time Dependent Reduction

    Science.gov (United States)

    Babaee, Hessam; Farazmand, Mohammad; Sapsis, Themis; Haller, George

    2016-11-01

    We present a method to compute Finite-Time Lyapunov Exponents (FTLE) of a dynamical system using Optimally Time-Dependent (OTD) reduction recently introduced by H. Babaee and T. P. Sapsis. The OTD modes are a set of finite-dimensional, time-dependent, orthonormal basis {ui (x , t) } |i=1N that capture the directions associated with transient instabilities. The evolution equation of the OTD modes is derived from a minimization principle that optimally approximates the most unstable directions over finite times. To compute the FTLE, we evolve a single OTD mode along with the nonlinear dynamics. We approximate the FTLE from the reduced system obtained from projecting the instantaneous linearized dynamics onto the OTD mode. This results in a significant reduction in the computational cost compared to conventional methods for computing FTLE. We demonstrate the efficiency of our method for double Gyre and ABC flows. ARO project 66710-EG-YIP.

  4. Wake-Effect Minimising Optimal Control of Wind Farms, with Load Reduction

    DEFF Research Database (Denmark)

    Borchersen, Anders Bech; Larsen, Jesper Abildgaard; Sivabalan, Senthuran

    2014-01-01

    the wake effects in the farm, while maintaining optimal power output. A feature which enables the MPC to spare certain turbines, while maintaining the power output is also implemented. The MPC controller is able to minimize the wake effect in the wind farm, when the power demand is not using the full......A power generating wind turbine causes a speed reduction and an added turbulence to the wind. Wind turbines in wind farms are often caught in these wakes and are found to have a higher structural load than non affected wind turbines. This article investigates the possibility of designing a control...... strategy which optimizes the power production, while minimizing the effect of the wakes in the wind farm. A generic wind farm model which is able to calculate the wind turbines influence on each other is developed. Models for the reduction in wind speed as well as turbulence in the wake effects...

  5. Model-Constrained Optimization Methods for Reduction of Parameterized Large-Scale Systems

    Science.gov (United States)

    2007-05-01

    colorful with his stereo karaoke system. Anh Hai, thanks for helping me move my furnitures many times, and for all the beers too! To all Vietnamese...visit them. My trips to Springfield would have been very boring if Anh Tung (+ Thao) and Anh Danh (+ Thuy) had not turn on their super stereo karaoke ...expensive to solve, e.g. for applications such as optimal design or probabilistic analyses. Model order reduction is a powerful tool that permits the

  6. Dimension reduction of decision variables for multireservoir operation: A spectral optimization model

    Science.gov (United States)

    Chen, Duan; Leon, Arturo S.; Gibson, Nathan L.; Hosseini, Parnian

    2016-01-01

    Optimizing the operation of a multireservoir system is challenging due to the high dimension of the decision variables that lead to a large and complex search space. A spectral optimization model (SOM), which transforms the decision variables from time domain to frequency domain, is proposed to reduce the dimensionality. The SOM couples a spectral dimensionality-reduction method called Karhunen-Loeve (KL) expansion within the routine of Nondominated Sorting Genetic Algorithm (NSGA-II). The KL expansion is used to represent the decision variables as a series of terms that are deterministic orthogonal functions with undetermined coefficients. The KL expansion can be truncated into fewer significant terms, and consequently, fewer coefficients by a predetermined number. During optimization, operators of the NSGA-II (e.g., crossover) are conducted only on the coefficients of the KL expansion rather than the large number of decision variables, significantly reducing the search space. The SOM is applied to the short-term operation of a 10-reservoir system in the Columbia River of the United States. Two scenarios are considered herein, the first with 140 decision variables and the second with 3360 decision variables. The hypervolume index is used to evaluate the optimization performance in terms of convergence and diversity. The evaluation of optimization performance is conducted for both conventional optimization model (i.e., NSGA-II without KL) and the SOM with different number of KL terms. The results show that the number of decision variables can be greatly reduced in the SOM to achieve a similar or better performance compared to the conventional optimization model. For the scenario with 140 decision variables, the optimal performance of the SOM model is found with six KL terms. For the scenario with 3360 decision variables, the optimal performance of the SOM model is obtained with 11 KL terms.

  7. Design and performance of subgrade biogeochemical reactors.

    Science.gov (United States)

    Gamlin, Jeff; Downey, Doug; Shearer, Brad; Favara, Paul

    2017-02-18

    Subgrade biogeochemical reactors (SBGRs), also commonly referred to as in situ bioreactors, are a unique technology for treatment of contaminant source areas and groundwater plume hot spots. SBGRs have most commonly been configured for enhanced reductive dechlorination (ERD) applications for chlorinated solvent treatment. However, they have also been designed for other contaminant classes using alternative treatment media. The SBGR technology typically consists of removal of contaminated soil via excavation or large-diameter augers, and backfill of the soil void with gravel and treatment amendments tailored to the target contaminant(s). In most cases SBGRs include installation of infiltration piping and a low-flow pumping system (typically solar-powered) to recirculate contaminated groundwater through the SBGR for treatment. SBGRs have been constructed in multiple configurations, including designs capable of meeting limited access restrictions at heavily industrialized sites, and at sites with restrictions on surface disturbance due to sensitive species or habitat issues. Typical performance results for ERD applications include 85 to 90 percent total molar reduction of chlorinated volatile organic compounds (CVOCs) near the SBGR and rapid clean-up of adjacent dissolved contaminant source areas. Based on a review of the literature and CH2M's field-scale results from over a dozen SBGRs with a least one year of performance data, important site-specific design considerations include: 1) hydraulic residence time should be long enough for sufficient treatment but not too long to create depressed pH and stagnant conditions (e.g., typically between 10 and 60 days), 2) reactor material should balance appropriate organic mulch as optimal bacterial growth media along with other organic additives that provide bioavailable organic carbon, 3) a variety of native bacteria are important to the treatment process, and 4) biologically mediated generation of iron sulfides along with

  8. Optimization of Vibration Reduction Ability of Ladder Tracks by FEM Coupled with ACO

    Directory of Open Access Journals (Sweden)

    Hao Jin

    2015-01-01

    Full Text Available Ladder track, which has drawn increased attention in scientific communities, is an effective method for reducing vibrations from underground railways. In order to optimize the vibration reduction ability of ladder track, a new method, that is, the finite element method (FEM coupled with ant colony optimization (ACO, has been proposed in this paper. We describe how to build the FEM model verified by the vibration tests in the Track Vibration Abatement and Control Laboratory and how to couple the FEM with ACO. The density and elasticity modulus of the sleeper pad are optimized using this method. After optimization, the vibration acceleration level of the supporting platform in the 1–200 Hz range was reduced from 102.8 dB to 94.4 dB. The optimized density of the sleeper pad is 620 kg/m3, and the optimized elasticity modulus of the sleeper pad is 6.25 × 106 N/m2.

  9. Biogeochemical Cycles in Degraded Lands

    Science.gov (United States)

    Davidson, Eric A.; Vieira, Ima Celia G.; ReisdeCarvalho, Claudio Jose; DeanedeAbreuSa, Tatiana; deSouzaMoutinho, Paulo R.; Figueiredo, Ricardo O.; Stone, Thomas A.

    2004-01-01

    The objectives of this project were to define and describe the types of landscapes that fall under the broad category of "degraded lands" and to study biogeochemical cycles across this range of degradation found in secondary forests. We define degraded land as that which has lost part of its capacity of renovation of a productive ecosystem, either in the context of agroecosystems or as native communities of vegetation. This definition of degradation permits evaluation of biogeochemical constraints to future land uses.

  10. Artifact reduction in short-scan CBCT by use of optimization-based reconstruction

    Science.gov (United States)

    Zhang, Zheng; Han, Xiao; Pearson, Erik; Pelizzari, Charles; Sidky, Emil Y.; Pan, Xiaochuan

    2016-05-01

    Increasing interest in optimization-based reconstruction in research on, and applications of, cone-beam computed tomography (CBCT) exists because it has been shown to have to potential to reduce artifacts observed in reconstructions obtained with the Feldkamp-Davis-Kress (FDK) algorithm (or its variants), which is used extensively for image reconstruction in current CBCT applications. In this work, we carried out a study on optimization-based reconstruction for possible reduction of artifacts in FDK reconstruction specifically from short-scan CBCT data. The investigation includes a set of optimization programs such as the image-total-variation (TV)-constrained data-divergency minimization, data-weighting matrices such as the Parker weighting matrix, and objects of practical interest for demonstrating and assessing the degree of artifact reduction. Results of investigative work reveal that appropriately designed optimization-based reconstruction, including the image-TV-constrained reconstruction, can reduce significant artifacts observed in FDK reconstruction in CBCT with a short-scan configuration.

  11. Helicopter vibration reduction using structural optimization with aeroelastic/multidisciplinary constraints - A survey

    Science.gov (United States)

    Friedmann, Peretz P.

    1991-01-01

    This paper presents a survey of the state-of-the-art in the field of structural optimization when applied to vibration reduction of helicopters in forward flight with aeroelastic and multidisciplinary constraints. It emphasizes the application of the modern approach where the optimization is formulated as a mathematical programming problem, the objective function consists of the vibration levels at the hub, and behavior constraints are imposed on the blade frequencies and aeroelastic stability margins, as well as on a number of additional ingredients that can have a significant effect on the overall performance and flight mechanics of the helicopter. It is shown that the integrated multidisciplinary optimization of rotorcraft offers the potential for substantial improvements, which can be achieved by careful preliminary design and analysis without requiring additional hardware such as rotor vibration absorbers of isolation systems.

  12. Reduction of scattering using thin all-dielectric shells designed by stochastic optimizer

    Energy Technology Data Exchange (ETDEWEB)

    Ladutenko, Konstantin, E-mail: fisik2000@mail.ru [ITMO University, 49 Kronverskii Ave., St. Petersburg 197101 (Russian Federation); Ioffe Physical-Technical Institute of the Russian Academy of Sciences, 26 Polytekhnicheskaya Str., St. Petersburg 194021 (Russian Federation); Peña-Rodríguez, Ovidio [Instituto de Fusión Nuclear, Universidad Politécnica de Madrid, José Gutiérrez Abascal 2, E-28006 Madrid (Spain); Melchakova, Irina; Yagupov, Ilya; Belov, Pavel [ITMO University, 49 Kronverskii Ave., St. Petersburg 197101 (Russian Federation)

    2014-11-14

    Adaptive differential evolution method has been used for optimization of all-dielectric multilayer coatings in order to reduce total scattering from spherical targets. The optimal refractive index profiles have been found for various sizes of targets and thicknesses of coatings. Few profile types that appear to be optimal for various geometrical parameters have been identified. Scattering of the target with diameter of 0.75 λ has been reduced by 85% using 0.16 λ thick coating formed by isotropic dielectric materials. For larger targets, scattering reduction becomes smaller, but it still reaches 50% for targets with the diameter of 1.5 λ. The obtained designs provide a route to implement cloaking without the use of magnetic and anisotropic metamaterials.

  13. Extracellular Electron Transport Coupling Biogeochemical Processes Centimeters

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Fossing, Henrik; Christensen, Peter Bondo

    2010-01-01

    of the oxygen uptake in laboratory incubations of initially homogenized and stabilized sediment. Using microsensors and process rate measurements we further investigated the effect of the electric currents on sediment biogeochemistry. Dissolved sulfide readily donated electrons to the networks and could...... confirmed the depth range of the electric communication and indicated donation of electrons directly from organotrophic bacteria. The separation of oxidation and reduction processes created steep pH gradients eventually causing carbonate precipitation at the surface. The results indicate that electron...... exchanging organisms have major biogeochemical importance as they allow widely separated electron donors and acceptors to react with one another....

  14. Brake squeal reduction of vehicle disc brake system with interval parameters by uncertain optimization

    Science.gov (United States)

    Lü, Hui; Yu, Dejie

    2014-12-01

    An uncertain optimization method for brake squeal reduction of vehicle disc brake system with interval parameters is presented in this paper. In the proposed method, the parameters of frictional coefficient, material properties and the thicknesses of wearing components are treated as uncertain parameters, which are described as interval variables. Attention is focused on the stability analysis of a brake system in squeal, and the stability of brake system is investigated via the complex eigenvalue analysis (CEA) method. The dominant unstable mode is extracted by performing CEA based on a linear finite element (FE) model, and the negative damping ratio corresponding to the dominant unstable mode is selected as the indicator of instability. The response surface method (RSM) is applied to approximate the implicit relationship between the unstable mode and the system parameters. A reliability-based optimization model for improving the stability of the vehicle disc brake system with interval parameters is constructed based on RSM, interval analysis and reliability analysis. The Genetic Algorithm is used to get the optimal values of design parameters from the optimization model. The stability analysis and optimization of a disc brake system are carried out, and the results show that brake squeal propensity can be reduced by using stiffer back plates. The proposed approach can be used to improve the stability of the vehicle disc brake system with uncertain parameters effectively.

  15. Cost-Optimal Pathways to 75% Fuel Reduction in Remote Alaskan Villages: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Simpkins, Travis; Cutler, Dylan; Hirsch, Brian; Olis, Dan; Anderson, Kate

    2015-10-28

    There are thousands of isolated, diesel-powered microgrids that deliver energy to remote communities around the world at very high energy costs. The Remote Communities Renewable Energy program aims to help these communities reduce their fuel consumption and lower their energy costs through the use of high penetration renewable energy. As part of this program, the REopt modeling platform for energy system integration and optimization was used to analyze cost-optimal pathways toward achieving a combined 75% reduction in diesel fuel and fuel oil consumption in a select Alaskan village. In addition to the existing diesel generator and fuel oil heating technologies, the model was able to select from among wind, battery storage, and dispatchable electric heaters to meet the electrical and thermal loads. The model results indicate that while 75% fuel reduction appears to be technically feasible it may not be economically viable at this time. When the fuel reduction target was relaxed, the results indicate that by installing high-penetration renewable energy, the community could lower their energy costs by 21% while still reducing their fuel consumption by 54%.

  16. Effects of optimal initial errors on predicting the seasonal reduction of the upstream Kuroshio transport

    Science.gov (United States)

    Zhang, Kun; Wang, Qiang; Mu, Mu; Liang, Peng

    2016-10-01

    With the Regional Ocean Modeling System (ROMS), we realistically simulated the transport variations of the upstream Kuroshio (referring to the Kuroshio from its origin to the south of Taiwan), particularly for the seasonal transport reduction. Then, we investigated the effects of the optimal initial errors estimated by the conditional nonlinear optimal perturbation (CNOP) approach on predicting the seasonal transport reduction. Two transport reduction events (denoted as Event 1 and Event 2) were chosen, and CNOP1 and CNOP2 were obtained for each event. By examining the spatial structures of the two types of CNOPs, we found that the dominant amplitudes are located around (128°E, 17°N) horizontally and in the upper 1000 m vertically. For each event, the two CNOPs caused large prediction errors. Specifically, at the prediction time, CNOP1 (CNOP2) develops into an anticyclonic (cyclonic) eddy-like structure centered around 124°E, leading to the increase (decrease) of the upstream Kuroshio transport. By investigating the time evolution of the CNOPs in Event 1, we found that the eddy-like structures originating from east of Luzon gradually grow and simultaneously propagate westward. The eddy-energetic analysis indicated that the errors obtain energy from the background state through barotropic and baroclinic instabilities and that the latter plays a more important role. These results suggest that improving the initial conditions in east of Luzon could lead to better prediction of the upstream Kuroshio transport variation.

  17. Optimal constrained multi-degree reduction of Bézier curves with explicit expressions based on divide and conquer

    Institute of Scientific and Technical Information of China (English)

    Lian ZHOU; Guo-jin WANG

    2009-01-01

    We decompose the problem of the optimal multi-degree reduction of Bezier curves with comers constraint into two simpler subproblems, namely making high order interpolations at the two endpoints without degree reduction, and doing optimal degree reduction without making high order interpolations at the two endpoints. Further, we convert the second subproblem into multi-degree reduction of Jacobi polynomials. Then, we can easily derive the optimal solution using orthonormality of Jaeobi polynomials and the least square method of unequally accurate measurement. This method of 'divide and conquer' has several advantages including maintaining high continuity at the two endpoints of the curve, doing multi-degree reduction only once, using explicit approximation expressions, estimating error in advance, low time cost, and high precision. More importantly, it is not only deduced simply and directly, but also can be easily extended to the degree reduction of surfaces. Finally, we present two examples to demonstrate the effectiveness of our algorithm.

  18. Sequential optimization and reliability assessment based on dimension reduction method for accurate and efficient reliability-based design optimization

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jong Min; Lee, Byung Chai; Lee, Ik Jin [KAIST, Daejeon (Korea, Republic of)

    2015-04-15

    This study develops an efficient and accurate methodology for reliability-based design optimization (RBDO) by combining the most probable point (MPP)-based dimension reduction method (DRM) to enhance accuracy and the sequential optimization and reliability assessment (SORA) to enhance efficiency. In many researches, first-order reliability method (FORM) has been utilized for RBDO methods due to its efficiency and simplicity. However, it might not be accurate enough for highly nonlinear performance functions. Therefore, the MPP-based DRM is introduced for the accurate reliability assessment in this study. Even though the MPP-based DRM significantly improves the accuracy, additional computations for the moment-based integration are required. It is desirable to reduce the number of reliability analyses in the RBDO process. Since decoupled approaches such as SORA reduce necessary reliability analyses considerably, DRM-based SORA is proposed in this study for accurate and efficient RBDO. Furthermore, convex linearization is introduced to approximate inactive probabilistic constraints to additionally improve the efficiency. The efficiency and accuracy of the proposed method are verified through numerical examples.

  19. Biogeochemical Cycles of Carbon and Sulfur

    Science.gov (United States)

    DesMarais, David J.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    The elements carbon (C) and sulfur (S) interact with each other across a network of elemental reservoirs that are interconnected by an array of physical, chemical and biological processes. These networks are termed the biogeochemical C and S cycles. The compounds of C are highly important, not only as organic matter, but also as atmospheric greenhouse gases, pH buffers in seawater, oxidation-reduction buffers virtually everywhere, and key magmatic constituents affecting plutonism and volcanism. The element S assumes important roles as an oxidation-reduction partner with C and Fe in biological systems, as a key constituent in magmas and volcanic gases, and as a major influence upon pH in certain environments. This presentation describes the modern biogeochemical C and S cycles. Measurements are described whereby stable isotopes can help to infer the nature and quantitative significance of biological and geological processes involved in the C and S cycles. This lecture also summarizes the geological and climatologic aspects of the ancient C and S cycles, as well as the planetary and extraterrestrial processes that influenced their evolution over millions to billions of years.

  20. Biogeochemical Cycles of Carbon and Sulfur

    Science.gov (United States)

    DesMarais, David J.; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    The elements carbon (C) and sulfur (S) interact with each other across a network of elemental reservoirs that are interconnected by an array of physical, chemical and biological processes. These networks are termed the biogeochemical C and S cycles. The compounds of C are highly important, not only as organic matter, but also as atmospheric greenhouse gases, pH buffers in seawater, oxidation-reduction buffers virtually everywhere, and key magmatic constituents affecting plutonism and volcanism. The element S assumes important roles as an oxidation-reduction partner with C and Fe in biological systems, as a key constituent in magmas and volcanic gases, and as a major influence upon pH in certain environments. This presentation describes the modern biogeochemical C and S cycles. Measurements are described whereby stable isotopes can help to infer the nature and quantitative significance of biological and geological processes involved in the C and S cycles. This lecture also summarizes the geological and climatologic aspects of the ancient C and S cycles, as well as the planetary and extraterrestrial processes that influenced their evolution over millions to billions of years.

  1. Reduction of edge effect on disk electrodes by optimized current waveform.

    Science.gov (United States)

    Wang, Boshuo; Petrossians, Artin; Weiland, James D

    2014-08-01

    Rectangular pulses applied to disk electrodes result in high current density at the edges of the disk, which can lead to electrode corrosion and tissue damage. We explored a method for reducing current density and corrosion, by varying the leading edge of the current pulse. Finite-element modeling and mathematical analysis were used to predict an optimal waveform that reduces current density at the edge while also maintaining short pulse duration. An approximation of the optimized waveform was implemented experimentally and applied to platinum disk electrodes. Surface analysis using energy-dispersive spectroscopy showed significant reduction of corrosion on the periphery of these electrodes after pulsing, compared to those pulsed with the control rectangular waveform.

  2. Model reduction algorithms for optimal control and importance sampling of diffusions

    Science.gov (United States)

    Hartmann, Carsten; Schütte, Christof; Zhang, Wei

    2016-08-01

    We propose numerical algorithms for solving optimal control and importance sampling problems based on simplified models. The algorithms combine model reduction techniques for multiscale diffusions and stochastic optimization tools, with the aim of reducing the original, possibly high-dimensional problem to a lower dimensional representation of the dynamics, in which only a few relevant degrees of freedom are controlled or biased. Specifically, we study situations in which either a reaction coordinate onto which the dynamics can be projected is known, or situations in which the dynamics shows strongly localized behavior in the small noise regime. No explicit assumptions about small parameters or scale separation have to be made. We illustrate the approach with simple, but paradigmatic numerical examples.

  3. Vehicular Traffic Optimization in VANETs: a Proposal for Nodes Re-routing and Congestion Reduction

    Directory of Open Access Journals (Sweden)

    Mauro Tropea

    2015-01-01

    Full Text Available Recently, vehicular networking has grown up in terms of interest and transmission capability, due to the possibility of exploiting the distributed communication paradigm in a mobile scenario, where moving nodes are represented by vehicles. In this paper, we focus our attention on the optimization of traffic flowing in a vehicular environment with vehicle-roadside capability. As shown in the next sections, the proposed idea exploits the information that is gathered by road-side units with the main aim of redirecting traffic flows (in terms of vehicles to less congested roads, with an overall system optimization, also in terms of Carbon Dioxide emissions reduction. A deep campaign of simulations has been carried out to give more effectiveness to our proposal.

  4. Kinetics based reaction optimization of enzyme catalysed reduction of formaldehyde to methanol with synchronous cofactor regeneration

    DEFF Research Database (Denmark)

    Marpani, Fauziah Binti; Sárossy, Zsuzsa; Pinelo, Manuel

    2017-01-01

    regeneration using either glucose dehydrogenase (System I) or xylose dehydrogenase (System II). A mathematical model of the enzyme kinetics was employed to identify the best reaction set-up for attaining optimal cofactor recycling rate and enzyme utilization efficiency. Targeted process optimization...... experiments were conducted to verify the kinetically modelled results. Repetitive reaction cycles were shown to enhance the yield of CH3 OH, increase the total turnover number (TTN) and the biocatalytic productivity rate (BPR) value for both system I and II whilst minimizing the exposure of the enzymes......Enzymatic reduction of carbon dioxide (CO2 ) to methanol (CH3 OH) can be accomplished using a designed set-up of three oxidoreductases utilizing reduced pyridine nucleotide (NADH) as cofactor for the reducing equivalents electron supply. For this enzyme system to function efficiently a balanced...

  5. Optimization of metal artefact reduction (MAR) sequences for MRI of total hip prostheses

    Energy Technology Data Exchange (ETDEWEB)

    Toms, A.P., E-mail: andoni.toms@nnuh.nhs.u [Department of Radiology, Norfolk and Norwich University Hospital Trust, Norwich, Norfolk NR4 7UY (United Kingdom); Smith-Bateman, C.; Malcolm, P.N.; Cahir, J. [Department of Radiology, Norfolk and Norwich University Hospital Trust, Norwich, Norfolk NR4 7UY (United Kingdom); Graves, M. [University Department of Radiology, Addenbrooke' s Hospital, Cambridge (United Kingdom)

    2010-06-15

    Aim: To describe the relative contribution of matrix size and bandwidth to artefact reduction in order to define optimal sequence parameters for metal artefact reduction (MAR) sequences for MRI of total hip prostheses. Methods and materials: A phantom was created using a Charnley total hip replacement. Mid-coronal T1-weighted (echo time 12 ms, repetition time 400 ms) images through the prosthesis were acquired with increasing bandwidths (150, 300, 454, 592, and 781 Hz/pixel) and increasing matrixes of 128, 256, 384, 512, 640, and 768 pixels square. Signal loss from the prosthesis and susceptibility artefact was segmented using an automated tool. Results: Over 90% of the achievable reduction in artefacts was obtained with matrixes of 256 x 256 or greater and a receiver bandwidth of approximately 400 Hz/pixel or greater. Thereafter increasing the receiver bandwidth or matrix had little impact on reducing susceptibility artefacts. Increasing the bandwidth produced a relative fall in the signal-to-noise ratio (SNR) of between 49 and 56% for a given matrix, but, in practice, the image quality was still satisfactory even with the highest bandwidth and largest matrix sizes. The acquisition time increased linearly with increasing matrix parameters. Conclusion: Over 90% of the achievable metal artefact reduction can be realized with mid-range matrices and receiver bandwidths on a clinical 1.5 T system. The loss of SNR from increasing receiver bandwidth, is preferable to long acquisition times, and therefore, should be the main tool for reducing metal artefact.

  6. Optimization and Modeling of Noise Reduction for Turbulent Jets with Induced Asymmetry

    Science.gov (United States)

    Rostamimonjezi, Sara

    This project relates to the development of next-generation high-speed aircraft that are efficient and environmentally compliant. The emphasis of the research is on reducing noise from high-performance engines that will power these aircraft. A strong component of engine noise is jet mixing noise that comes from the turbulent mixing process between the high-speed exhaust flow of the engine and the atmosphere. The fan flow deflection method (FFD) suppresses jet noise by deflecting the fan stream downward, by a few degrees, with respect to the core stream. This reduces the convective Mach number of the primary shear layer and turbulent kinetic energy in the downward direction and therefore reduces the noise emitted towards the ground. The redistribution of the fan stream is achieved with inserting airfoil-shaped vanes inside the fan duct. Aerodynamic optimization of FFD has been done by Dr. Juntao Xiong using a computational fluid dynamics code to maximize reduction of noise perceived by the community while minimizing aerodynamic losses. The optimal vane airfoils are used in a parametric experimental study of 50 4-vane deflector configurations. The vane chord length, angle of attack, and azimuthal location are the parameters studied in acoustic optimization. The best vane configuration yields a reduction in cumulative (downward + sideline) effective perceived noise level (EPNL) of 5.3 dB. The optimization study underscores the sensitivity of FFD to deflector parameters and the need for careful design in the practical implementation of this noise reduction approach. An analytical model based on Reynolds Averaged Navier Stokes (RANS) and acoustic analogy is developed to predict the spectral changes from a known baseline in the direction of peak emission. A generalized form for space-time correlation is introduced that allows shapes beyond the traditional exponential forms. Azimuthal directivity based on the wavepacket model of jet noise is integrated with the acoustic

  7. Optimization-based image reconstruction with artifact reduction in C-arm CBCT

    Science.gov (United States)

    Xia, Dan; Langan, David A.; Solomon, Stephen B.; Zhang, Zheng; Chen, Buxin; Lai, Hao; Sidky, Emil Y.; Pan, Xiaochuan

    2016-10-01

    We investigate an optimization-based reconstruction, with an emphasis on image-artifact reduction, from data collected in C-arm cone-beam computed tomography (CBCT) employed in image-guided interventional procedures. In the study, an image to be reconstructed is formulated as a solution to a convex optimization program in which a weighted data divergence is minimized subject to a constraint on the image total variation (TV); a data-derivative fidelity is introduced in the program specifically for effectively suppressing dominant, low-frequency data artifact caused by, e.g. data truncation; and the Chambolle-Pock (CP) algorithm is tailored to reconstruct an image through solving the program. Like any other reconstructions, the optimization-based reconstruction considered depends upon numerous parameters. We elucidate the parameters, illustrate their determination, and demonstrate their impact on the reconstruction. The optimization-based reconstruction, when applied to data collected from swine and patient subjects, yields images with visibly reduced artifacts in contrast to the reference reconstruction, and it also appears to exhibit a high degree of robustness against distinctively different anatomies of imaged subjects and scanning conditions of clinical significance. Knowledge and insights gained in the study may be exploited for aiding in the design of practical reconstructions of truly clinical-application utility.

  8. PAPR reduction in FBMC using an ACE-based linear programming optimization

    Science.gov (United States)

    van der Neut, Nuan; Maharaj, Bodhaswar TJ; de Lange, Frederick; González, Gustavo J.; Gregorio, Fernando; Cousseau, Juan

    2014-12-01

    This paper presents four novel techniques for peak-to-average power ratio (PAPR) reduction in filter bank multicarrier (FBMC) modulation systems. The approach extends on current PAPR reduction active constellation extension (ACE) methods, as used in orthogonal frequency division multiplexing (OFDM), to an FBMC implementation as the main contribution. The four techniques introduced can be split up into two: linear programming optimization ACE-based techniques and smart gradient-project (SGP) ACE techniques. The linear programming (LP)-based techniques compensate for the symbol overlaps by utilizing a frame-based approach and provide a theoretical upper bound on achievable performance for the overlapping ACE techniques. The overlapping ACE techniques on the other hand can handle symbol by symbol processing. Furthermore, as a result of FBMC properties, the proposed techniques do not require side information transmission. The PAPR performance of the techniques is shown to match, or in some cases improve, on current PAPR techniques for FBMC. Initial analysis of the computational complexity of the SGP techniques indicates that the complexity issues with PAPR reduction in FBMC implementations can be addressed. The out-of-band interference introduced by the techniques is investigated. As a result, it is shown that the interference can be compensated for, whilst still maintaining decent PAPR performance. Additional results are also provided by means of a study of the PAPR reduction of the proposed techniques at a fixed clipping probability. The bit error rate (BER) degradation is investigated to ensure that the trade-off in terms of BER degradation is not too severe. As illustrated by exhaustive simulations, the SGP ACE-based technique proposed are ideal candidates for practical implementation in systems employing the low-complexity polyphase implementation of FBMC modulators. The methods are shown to offer significant PAPR reduction and increase the feasibility of FBMC as

  9. An Ant Colony Optimization Based Dimension Reduction Method for High-Dimensional Datasets

    Institute of Scientific and Technical Information of China (English)

    Ying Li; Gang Wang; Huiling Chen; Lian Shi; Lei Qin

    2013-01-01

    In this paper,a bionic optimization algorithm based dimension reduction method named Ant Colony Optimization -Selection (ACO-S) is proposed for high-dimensional datasets.Because microarray datasets comprise tens of thousands of features (genes),they are usually used to test the dimension reduction techniques.ACO-S consists of two stages in which two well-known ACO algorithms,namely ant system and ant colony system,are utilized to seek for genes,respectively.In the first stage,a modified ant system is used to filter the nonsignificant genes from high-dimensional space,and a number of promising genes are reserved in the next step.In the second stage,an improved ant colony system is applied to gene selection.In order to enhance the search ability of ACOs,we propose a method for calculating priori available heuristic information and design a fuzzy logic controller to dynamically adjust the number of ants in ant colony system.Furthermore,we devise another fuzzy logic controller to tune the parameter (q0) in ant colony system.We evaluate the performance of ACO-S on five microarray datasets,which have dimensions varying from 7129 to 12000.We also compare the performance of ACO-S with the results obtained from four existing well-known bionic optimization algorithms.The comparison results show that ACO-S has a notable ability to generate a gene subset with the smallest size and salient features while yielding high classification accuracy.The comparative results generated by ACO-S adopting different classifiers are also given.The proposed method is shown to be a promising and effective tool for mining high-dimension data and mobile robot navigation.

  10. Hierarchically porous carbons with optimized nitrogen doping as highly active electrocatalysts for oxygen reduction

    Science.gov (United States)

    Liang, Hai-Wei; Zhuang, Xiaodong; Brüller, Sebastian; Feng, Xinliang; Müllen, Klaus

    2014-09-01

    Development of efficient, low-cost and stable electrocatalysts as the alternative to platinum for the oxygen reduction reaction is of significance for many important electrochemical devices, such as fuel cells, metal-air batteries and chlor-alkali electrolysers. Here we report a highly active nitrogen-doped, carbon-based, metal-free oxygen reduction reaction electrocatalyst, prepared by a hard-templating synthesis, for which nitrogen-enriched aromatic polymers and colloidal silica are used as precursor and template, respectively, followed by ammonia activation. Our protocol allows for the simultaneous optimization of both porous structures and surface functionalities of nitrogen-doped carbons. Accordingly, the prepared catalysts show the highest oxygen reduction reaction activity (half-wave potential of 0.85 V versus reversible hydrogen electrode with a low loading of 0.1 mg cm-2) in alkaline media among all reported metal-free catalysts. Significantly, when used for constructing the air electrode of zinc-air battery, our metal-free catalyst outperforms the state-of the-art platinum-based catalyst.

  11. Reduction of wafer-edge overlay errors using advanced correction models, optimized for minimal metrology requirements

    Science.gov (United States)

    Kim, Min-Suk; Won, Hwa-Yeon; Jeong, Jong-Mun; Böcker, Paul; Vergaij-Huizer, Lydia; Kupers, Michiel; Jovanović, Milenko; Sochal, Inez; Ryan, Kevin; Sun, Kyu-Tae; Lim, Young-Wan; Byun, Jin-Moo; Kim, Gwang-Gon; Suh, Jung-Joon

    2016-03-01

    In order to optimize yield in DRAM semiconductor manufacturing for 2x nodes and beyond, the (processing induced) overlay fingerprint towards the edge of the wafer needs to be reduced. Traditionally, this is achieved by acquiring denser overlay metrology at the edge of the wafer, to feed field-by-field corrections. Although field-by-field corrections can be effective in reducing localized overlay errors, the requirement for dense metrology to determine the corrections can become a limiting factor due to a significant increase of metrology time and cost. In this study, a more cost-effective solution has been found in extending the regular correction model with an edge-specific component. This new overlay correction model can be driven by an optimized, sparser sampling especially at the wafer edge area, and also allows for a reduction of noise propagation. Lithography correction potential has been maximized, with significantly less metrology needs. Evaluations have been performed, demonstrating the benefit of edge models in terms of on-product overlay performance, as well as cell based overlay performance based on metrology-to-cell matching improvements. Performance can be increased compared to POR modeling and sampling, which can contribute to (overlay based) yield improvement. Based on advanced modeling including edge components, metrology requirements have been optimized, enabling integrated metrology which drives down overall metrology fab footprint and lithography cycle time.

  12. Optimized Reduction of Unsteady Radial Forces in a Singlechannel Pump for Wastewater Treatment

    Science.gov (United States)

    Kim, Jin-Hyuk; Cho, Bo-Min; Choi, Young-Seok; Lee, Kyoung-Yong; Peck, Jong-Hyeon; Kim, Seon-Chang

    2016-11-01

    A single-channel pump for wastewater treatment was optimized to reduce unsteady radial force sources caused by impeller-volute interactions. The steady and unsteady Reynolds- averaged Navier-Stokes equations using the shear-stress transport turbulence model were discretized by finite volume approximations and solved on tetrahedral grids to analyze the flow in the single-channel pump. The sweep area of radial force during one revolution and the distance of the sweep-area center of mass from the origin were selected as the objective functions; the two design variables were related to the internal flow cross-sectional area of the volute. These objective functions were integrated into one objective function by applying the weighting factor for optimization. Latin hypercube sampling was employed to generate twelve design points within the design space. A response-surface approximation model was constructed as a surrogate model for the objectives, based on the objective function values at the generated design points. The optimized results showed considerable reduction in the unsteady radial force sources in the optimum design, relative to those of the reference design.

  13. A biogeochemical cycle for aluminium?

    Science.gov (United States)

    Exley, Christopher

    2003-09-15

    The elaboration of biogeochemical cycles for elements which are known to be essential for life has enabled a broad appreciation of the homeostatic mechanisms which underlie element essentiality. In particular they can be used effectively to identify any part played by human activities in element cycling and to predict how such activities might impact upon the lithospheric and biospheric availability of an element in the future. The same criteria were the driving force behind the construction of a biogeochemical cycle for aluminium, a non-essential element which is a known ecotoxicant and a suspected health risk in humans. The purpose of this exercise was to examine the concept of a biogeochemical cycle for aluminium and not to review the biogeochemistry of this element. The cycle as presented is rudimentary and qualitative though, even in this nascent form, it is informative and predictive and, for these reasons alone, it is deserving of future quantification. A fully fledged biogeochemical cycle for aluminium should explain the biospheric abundance of this element and whether we should expect its (continued) active involvement in biochemical evolution.

  14. Archaea in biogeochemical cycles.

    Science.gov (United States)

    Offre, Pierre; Spang, Anja; Schleper, Christa

    2013-01-01

    Archaea constitute a considerable fraction of the microbial biomass on Earth. Like Bacteria they have evolved a variety of energy metabolisms using organic and/or inorganic electron donors and acceptors, and many of them are able to fix carbon from inorganic sources. Archaea thus play crucial roles in the Earth's global geochemical cycles and influence greenhouse gas emissions. Methanogenesis and anaerobic methane oxidation are important steps in the carbon cycle; both are performed exclusively by anaerobic archaea. Oxidation of ammonia to nitrite is performed by Thaumarchaeota. They represent the only archaeal group that resides in large numbers in the global aerobic terrestrial and marine environments on Earth. Sulfur-dependent archaea are confined mostly to hot environments, but metal leaching by acidophiles and reduction of sulfate by anaerobic, nonthermophilic methane oxidizers have a potential impact on the environment. The metabolisms of a large number of archaea, in particular those dominating the subsurface, remain to be explored.

  15. Optimally amplified large-scale streaks and drag reduction in turbulent pipe flow.

    Science.gov (United States)

    Willis, Ashley P; Hwang, Yongyun; Cossu, Carlo

    2010-09-01

    The optimal amplifications of small coherent perturbations within turbulent pipe flow are computed for Reynolds numbers up to one million. Three standard frameworks are considered: the optimal growth of an initial condition, the response to harmonic forcing and the Karhunen-Loève (proper orthogonal decomposition) analysis of the response to stochastic forcing. Similar to analyses of the turbulent plane channel flow and boundary layer, it is found that streaks elongated in the streamwise direction can be greatly amplified from quasistreamwise vortices, despite linear stability of the mean flow profile. The most responsive perturbations are streamwise uniform and, for sufficiently large Reynolds number, the most responsive azimuthal mode is of wave number m=1 . The response of this mode increases with the Reynolds number. A secondary peak, where m corresponds to azimuthal wavelengths λ_{θ}^{+}≈70-90 in wall units, also exists in the amplification of initial conditions and in premultiplied response curves for the forced problems. Direct numerical simulations at Re=5300 confirm that the forcing of m=1,2 and m=4 optimal structures results in the large response of coherent large-scale streaks. For moderate amplitudes of the forcing, low-speed streaks become narrower and more energetic, whereas high-speed streaks become more spread. It is further shown that drag reduction can be achieved by forcing steady large-scale structures, as anticipated from earlier investigations. Here the energy balance is calculated. At Re=5300 it is shown that, due to the small power required by the forcing of optimal structures, a net power saving of the order of 10% can be achieved following this approach, which could be relevant for practical applications.

  16. Ant Colony Optimization Algorithm For PAPR Reduction In Multicarrier Code Division Multiple Access System

    Directory of Open Access Journals (Sweden)

    Kanchan Singla

    2014-06-01

    Full Text Available MC CDMA is a rising candidate for future generation broadband wireless communication and gained great attention from researchers. It provides benefits of both OFDM and CDMA. Main challenging problem of MC CDMA is high PAPR. It occurs in HPA and reduces system efficiency. There are many PAPR reduction techniques for MC CDMA. In this paper we proposed Ant colony optimization algorithm to reduce PAPR with different number of user using BPSK and QPSK modulation. ACO is a metaheuristic technique and based on the foraging behavior of real ants. It provides solution to many complex problems. Simulation result proves that ACO using BPSK modulation is effective for reducing PAPR in MC CDMA.

  17. Analysis of GHG Emission Reduction in South Korea Using a CO2 Transportation Network Optimization Model

    Directory of Open Access Journals (Sweden)

    Suk Ho Jin

    2017-07-01

    Full Text Available Korea’s national carbon capture and storage (CCS master plan aims to commercialize CCS projects by 2030. Furthermore, the Korean government is forced to reduce emissions from various sectors, including industries and power generation, by 219 million tons by 2030. This study analyzes a few scenarios of Korean CCS projects with a CO2 pipeline transportation network optimization model for minimizing the total facility cost and pipeline cost. Our scenarios are based on the “2030 asic roadmap for reducing greenhouse gases” established by the government. The results for each scenario demonstrate that the effective design and implementation of CO2 pipeline network enables the lowering of CO2 units cost. These suggest that CO2 transportation networks, which connect the capture and sequestration parts, will be more important in the future and can be used to substitute and supplement the emission reduction target in case the execution of other reduction options faces uncertainty. Our mathematical model and scenario designs will be helpful for various countries which plan to introduce CCS technology.

  18. Optimized Herschel/PACS photometer observing and data reduction strategies for moving solar system targets

    CERN Document Server

    Cs., Kiss; E., Vilenius; A., Pál; P., Santos-Sanz; E., Lellouch; G., Marton; E., Verebélyi; N., Szalai; P., Hartogh; J., Stansberry; F., Henry; A, Delsanti

    2013-01-01

    The "TNOs are Cool!: A survey of the trans-Neptunian region" is a Herschel Open Time Key Program that aims to characterize planetary bodies at the outskirts of the Solar System using PACS and SPIRE data, mostly taken as scan-maps. In this paper we summarize our PACS data reduction scheme that uses a modified version of the standard pipeline for basic data reduction, optimized for faint, moving targets. Due to the low flux density of our targets the observations are confusion noise limited or at least often affected by bright nearby background sources at 100 and 160\\,$\\mu$m. To overcome these problems we developed techniques to characterize and eliminate the background at the positions of our targets and a background matching technique to compensate for pointing errors. We derive a variety of maps as science data products that are used depending on the source flux and background levels and the scientific purpose. Our techniques are also applicable to a wealth of other Herschel solar system photometric observat...

  19. One-Dimensional Optimal System and Similarity Reductions of Wu—Zhang Equation

    Science.gov (United States)

    Xiong, Na; Li, Yu-Qi; Chen, Jun-Chao; Chen, Yong

    2016-07-01

    The one-dimensional optimal system for the Lie symmetry group of the (2+1)-dimensional Wu—Zhang equation is constructed by the general and systematic approach. Based on the optimal system, the complete and inequivalent symmetry reduction systems are presented in the form of table. It is noteworthy that a new Painlevé integrable equation with constant coefficient is in the table besides the classic Boussinesq equation and the steady case of the Wu-Zhang equation. Supported by the Global Change Research Program of China under Grant No. 2015CB953904, National Natural Science Foundation of China under Grant Nos. 11375090, 11275072 and 11435005, Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20120076110024, the Network Information Physics Calculation of Basic Research Innovation Research Group of China under Grant No. 61321064, Shanghai Collaborative Innovation Center of Trustworthy Software for Internet of Things under Grant No. ZF1213, and the Zhejiang Provincial Natural Science Foundation of China under Grant No. LY14A010005

  20. Optimal Wavelength Selection in Ultraviolet Spectroscopy for the Estimation of Toxin Reduction Ratio during Hemodialysis

    Directory of Open Access Journals (Sweden)

    Amir Ghanifar

    2016-06-01

    Full Text Available Introduction The concentration of substances, including urea, creatinine, and uric acid, can be used as an index to measure toxic uremic solutes in the blood during dialysis and interdialytic intervals. The on-line monitoring of toxin concentration allows for the clearance measurement of some low-molecular-weight solutes at any time during hemodialysis.The aim of this study was to determine the optimal wavelength for estimating the changes in urea, creatinine, and uric acid in dialysate, using ultraviolet (UV spectroscopy. Materials and Methods In this study, nine uremic patients were investigated, using on-line spectrophotometry. The on-line absorption measurements (UV radiation were performed with a spectrophotometer module, connected to the fluid outlet of the dialysis machine. Dialysate samples were obtained and analyzed, using standard biochemical methods. Optimal wavelengths for both creatinine and uric acid were selected by using a combination of genetic algorithms (GAs, i.e., GA-partial least squares (GA-PLS and interval partial least squares (iPLS. Results The Artifitial Neural Network (ANN sensitivity analysis determined the wavelengths of the UV band most suitable for estimating the concentration of creatinine and uric acid. The two optimal wavelengths were 242 and 252 nm for creatinine and 295 and 298 nm for uric acid. Conclusion It can be concluded that the reduction ratio of creatinine and uric acid (dialysis efficiency could be continuously monitored during hemodialysis by UV spectroscopy.Compared to the conventional method, which is particularly sensitive to the sampling technique and involves post-dialysis blood sampling, iterative measurements throughout the dialysis session can yield more reliable data.

  1. Temporal Data Set Reduction Based on D-Optimality for Quantitative FLIM-FRET Imaging.

    Science.gov (United States)

    Omer, Travis; Intes, Xavier; Hahn, Juergen

    2015-01-01

    Fluorescence lifetime imaging (FLIM) when paired with Förster resonance energy transfer (FLIM-FRET) enables the monitoring of nanoscale interactions in living biological samples. FLIM-FRET model-based estimation methods allow the quantitative retrieval of parameters such as the quenched (interacting) and unquenched (non-interacting) fractional populations of the donor fluorophore and/or the distance of the interactions. The quantitative accuracy of such model-based approaches is dependent on multiple factors such as signal-to-noise ratio and number of temporal points acquired when sampling the fluorescence decays. For high-throughput or in vivo applications of FLIM-FRET, it is desirable to acquire a limited number of temporal points for fast acquisition times. Yet, it is critical to acquire temporal data sets with sufficient information content to allow for accurate FLIM-FRET parameter estimation. Herein, an optimal experimental design approach based upon sensitivity analysis is presented in order to identify the time points that provide the best quantitative estimates of the parameters for a determined number of temporal sampling points. More specifically, the D-optimality criterion is employed to identify, within a sparse temporal data set, the set of time points leading to optimal estimations of the quenched fractional population of the donor fluorophore. Overall, a reduced set of 10 time points (compared to a typical complete set of 90 time points) was identified to have minimal impact on parameter estimation accuracy (≈5%), with in silico and in vivo experiment validations. This reduction of the number of needed time points by almost an order of magnitude allows the use of FLIM-FRET for certain high-throughput applications which would be infeasible if the entire number of time sampling points were used.

  2. A quadratic programming method for optimal degree reduction of Bézier curves with G1-conitnuity

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents a quadratic programming method for optimal multi-degree reduction of Bézier curves with G1-continuity. The L2 and l2 measures of distances between the two curves are used as the objective functions. The two additional parameters, available from the coincidence of the oriented tangents, are constrained to be positive so as to satisfy the solvability condition. Finally, degree reduction is changed to solve a quadratic problem of two parameters with linear constraints. Applica

  3. Breast Cancer-Related Arm Lymphedema: Incidence Rates, Diagnostic Techniques, Optimal Management and Risk Reduction Strategies

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Chirag [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States); Vicini, Frank A., E-mail: fvicini@beaumont.edu [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States)

    2011-11-15

    As more women survive breast cancer, long-term toxicities affecting their quality of life, such as lymphedema (LE) of the arm, gain importance. Although numerous studies have attempted to determine incidence rates, identify optimal diagnostic tests, enumerate efficacious treatment strategies and outline risk reduction guidelines for breast cancer-related lymphedema (BCRL), few groups have consistently agreed on any of these issues. As a result, standardized recommendations are still lacking. This review will summarize the latest data addressing all of these concerns in order to provide patients and health care providers with optimal, contemporary recommendations. Published incidence rates for BCRL vary substantially with a range of 2-65% based on surgical technique, axillary sampling method, radiation therapy fields treated, and the use of chemotherapy. Newer clinical assessment tools can potentially identify BCRL in patients with subclinical disease with prospective data suggesting that early diagnosis and management with noninvasive therapy can lead to excellent outcomes. Multiple therapies exist with treatments defined by the severity of BCRL present. Currently, the standard of care for BCRL in patients with significant LE is complex decongestive physiotherapy (CDP). Contemporary data also suggest that a multidisciplinary approach to the management of BCRL should begin prior to definitive treatment for breast cancer employing patient-specific surgical, radiation therapy, and chemotherapy paradigms that limit risks. Further, prospective clinical assessments before and after treatment should be employed to diagnose subclinical disease. In those patients who require aggressive locoregional management, prophylactic therapies and the use of CDP can help reduce the long-term sequelae of BCRL.

  4. Reliability-oriented multi-objective optimal decision-making approach for uncertainty-based watershed load reduction

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Feifei [College of Environmental Science and Engineering, Key Laboratory of Water and Sediment Sciences (MOE), Peking University, Beijing 100871 (China); Liu, Yong, E-mail: yongliu@pku.edu.cn [College of Environmental Science and Engineering, Key Laboratory of Water and Sediment Sciences (MOE), Peking University, Beijing 100871 (China); Institute of Water Sciences, Peking University, Beijing 100871 (China); Su, Han [College of Environmental Science and Engineering, Key Laboratory of Water and Sediment Sciences (MOE), Peking University, Beijing 100871 (China); Zou, Rui [Tetra Tech, Inc., 10306 Eaton Place, Ste 340, Fairfax, VA 22030 (United States); Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed, Kunming 650034 (China); Guo, Huaicheng [College of Environmental Science and Engineering, Key Laboratory of Water and Sediment Sciences (MOE), Peking University, Beijing 100871 (China)

    2015-05-15

    Water quality management and load reduction are subject to inherent uncertainties in watershed systems and competing decision objectives. Therefore, optimal decision-making modeling in watershed load reduction is suffering due to the following challenges: (a) it is difficult to obtain absolutely “optimal” solutions, and (b) decision schemes may be vulnerable to failure. The probability that solutions are feasible under uncertainties is defined as reliability. A reliability-oriented multi-objective (ROMO) decision-making approach was proposed in this study for optimal decision making with stochastic parameters and multiple decision reliability objectives. Lake Dianchi, one of the three most eutrophic lakes in China, was examined as a case study for optimal watershed nutrient load reduction to restore lake water quality. This study aimed to maximize reliability levels from considerations of cost and load reductions. The Pareto solutions of the ROMO optimization model were generated with the multi-objective evolutionary algorithm, demonstrating schemes representing different biases towards reliability. The Pareto fronts of six maximum allowable emission (MAE) scenarios were obtained, which indicated that decisions may be unreliable under unpractical load reduction requirements. A decision scheme identification process was conducted using the back propagation neural network (BPNN) method to provide a shortcut for identifying schemes at specific reliability levels for decision makers. The model results indicated that the ROMO approach can offer decision makers great insights into reliability tradeoffs and can thus help them to avoid ineffective decisions. - Highlights: • Reliability-oriented multi-objective (ROMO) optimal decision approach was proposed. • The approach can avoid specifying reliability levels prior to optimization modeling. • Multiple reliability objectives can be systematically balanced using Pareto fronts. • Neural network model was used to

  5. Optimal scenario balance of reduction in costs and greenhouse gas emissions for municipal solid waste management

    Institute of Scientific and Technical Information of China (English)

    邓娜; 张强; 陈广武; 齐长青; 崔文谦; 张于峰; 马洪亭

    2015-01-01

    To reduce carbon intensity, an improved management method balancing the reduction in costs and greenhouse gas (GHG) emissions is required for Tianjin’s waste management system. Firstly, six objective functions, namely, cost minimization, GHG minimization, eco-efficiency minimization, cost maximization, GHG maximization and eco-efficiency maximization, are built and subjected to the same constraints with each objective function corresponding to one scenario. Secondly, GHG emissions and costs are derived from the waste flow of each scenario. Thirdly, the range of GHG emissions and costs of other potential scenarios are obtained and plotted through adjusting waste flow with infinitely possible step sizes according to the correlation among the above six scenarios. And the optimal scenario is determined based on this range. The results suggest the following conclusions. 1) The scenarios located on the border between scenario cost minimization and GHG minimization create an optimum curve, and scenario GHG minimization has the smallest eco-efficiency on the curve;2) Simple pursuit of eco-efficiency minimization using fractional programming may be unreasonable; 3) Balancing GHG emissions from incineration and landfills benefits Tianjin’s waste management system as it reduces GHG emissions and costs.

  6. Biogeochemical cycling and remote sensing

    Science.gov (United States)

    Peterson, D. L.

    1985-01-01

    Research is underway at the NASA Ames Research Center that is concerned with aspects of the nitrogen cycle in terrestrial ecosystems. An interdisciplinary research group is attempting to correlate nitrogen transformations, processes, and productivity with variables that can be remotely sensed. Recent NASA and other publications concerning biogeochemical cycling at global scales identify attributes of vegetation that could be related or explain the spatial variation in biologically functional variables. These functional variables include net primary productivity, annual nitrogen mineralization, and possibly the emission rate of nitrous oxide from soils.

  7. An Analytical Particle Biogeochemical Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Evaluation of the technical and scientific feasibility of developing a model and sensor for the analytical optical determination of particle biogeochemical...

  8. Optimal deployment schedule of an active twist rotor for performance enhancement and vibration reduction in high-speed flights

    Directory of Open Access Journals (Sweden)

    Young H. YOU

    2017-08-01

    Full Text Available The best active twist schedules exploiting various waveform types are sought taking advantage of the global search algorithm for the reduction of hub vibration and/or power required of a rotor in high-speed conditions. The active twist schedules include two non-harmonic inputs formed based on segmented step functions as well as the simple harmonic waveform input. An advanced Particle Swarm assisted Genetic Algorithm (PSGA is employed for the optimizer. A rotorcraft Computational Structural Dynamics (CSD code CAMRAD II is used to perform the rotor aeromechanics analysis. A Computation Fluid Dynamics (CFD code is coupled with CSD for verification and some physical insights. The PSGA optimization results are verified against the parameter sweep study performed using the harmonic actuation. The optimum twist schedules according to the performance and/or vibration reduction strategy are obtained and their optimization gains are compared between the actuation cases. A two-phase non-harmonic actuation schedule demonstrates the best outcome in decreasing the power required while a four-phase non-harmonic schedule results in the best vibration reduction as well as the simultaneous reductions in the power required and vibration. The mechanism of reduction to the performance gains is identified illustrating the section airloads, angle-of-attack distribution, and elastic twist deformation predicted by the present approaches.

  9. Recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation: process optimization and mineralogical study

    Science.gov (United States)

    Jiao, Rui-min; Xing, Peng; Wang, Cheng-yan; Ma, Bao-zhong; Chen, Yong-Qiang

    2017-09-01

    Currently, the majority of copper tailings are not effectively developed. Worldwide, large amounts of copper tailings generated from copper production are continuously dumped, posing a potential environmental threat. Herein, the recovery of iron from copper tailings via low-temperature direct reduction and magnetic separation was conducted; process optimization was carried out, and the corresponding mineralogy was investigated. The reduction time, reduction temperature, reducing agent (coal), calcium chloride additive, grinding time, and magnetic field intensity were examined for process optimization. Mineralogical analyses of the sample, reduced pellets, and magnetic concentrate under various conditions were performed by X-ray diffraction, optical microscopy, and scanning electron microscopy-energy-dispersive X-ray spectrometry to elucidate the iron reduction and growth mechanisms. The results indicated that the optimum parameters of iron recovery include a reduction temperature of 1150°C, a reduction time of 120 min, a coal dosage of 25%, a calcium chloride dosage of 2.5%, a magnetic field intensity of 100 mT, and a grinding time of 1 min. Under these conditions, the iron grade in the magnetic concentrate was greater than 90%, with an iron recovery ratio greater than 95%.

  10. Model reduction for dynamic real-time optimization of chemical processes

    NARCIS (Netherlands)

    Van den Berg, J.

    2005-01-01

    The value of models in process industries becomes apparent in practice and literature where numerous successful applications are reported. Process models are being used for optimal plant design, simulation studies, for off-line and online process optimization. For online optimization applications th

  11. Shape Optimization for Drag Reduction in Linked Bodies using Evolution Strategies and the Hybrid Wavelet Collocation - Brinkman Penalization Method

    Science.gov (United States)

    Vasilyev, Oleg V.; Gazzola, Mattia; Koumoutsakos, Petros

    2010-11-01

    In this talk we discuss preliminary results for the use of hybrid wavelet collocation - Brinkman penalization approach for shape optimization for drag reduction in flows past linked bodies. This optimization relies on Adaptive Wavelet Collocation Method along with the Brinkman penalization technique and the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). Adaptive wavelet collocation method tackles the problem of efficiently resolving a fluid flow on a dynamically adaptive computational grid, while a level set approach is used to describe the body shape and the Brinkman volume penalization allows for an easy variation of flow geometry without requiring body-fitted meshes. We perform 2D simulations of linked bodies in order to investigate whether flat geometries are optimal for drag reduction. In order to accelerate the costly cost function evaluations we exploit the inherent parallelism of ES and we extend the CMA-ES implementation to a multi-host framework. This framework allows for an easy distribution of the cost function evaluations across several parallel architectures and it is not limited to only one computing facility. The resulting optimal shapes are geometrically consistent with the shapes that have been obtained in the pioneering wind tunnel experiments for drag reduction using Evolution Strategies by Ingo Rechenberg.

  12. Reduction of fatigue loads on jacket substructure through blade design optimization for multimegawatt wind turbines at 50 m water depths

    DEFF Research Database (Denmark)

    NJOMO WANDJI, Wilfried; Pavese, Christian; Natarajan, Anand;

    2016-01-01

    This paper addresses the reduction of the fore-aft damage equivalent moment at the tower base for multi-megawatt offshore wind turbines mounted on jacket type substructures at 50 m water depths. The study investigates blade design optimization of a reference 10 MW wind turbine under standard wind...... conditions of onshore sites. The blade geometry and structure is optimized to yield a design that minimizes tower base fatigue loads without significant loss of power production compared to that of the reference setup. The resulting blade design is then mounted on a turbine supported by a jacket and placed...

  13. Topology optimization for reduction of thermo-elastic dissipation in MEMS resonators

    DEFF Research Database (Denmark)

    Gerrard, Dustin D.; Chen, Yunhan; Chandorkar, Saurabh A.

    2017-01-01

    This paper presents a topology optimization approach for reducing thermo-elastic dissipation (TED) in MEMS resonators. This algorithm is applied to a clamped-clamped resonant beam to maximize the quality factor (Q). Optimal designs have a Q ten times higher than a solid beam and are 75% higher than...... previously optimized devices. Furthermore, new designs have intuitive topologies. Beams are fabricated in silicon wafers and experimental measurements of Q agree well with simulation....

  14. Optimizing master event templates for CTBT monitoring with dimensionality reduction techniques: real waveforms vs. synthetics.

    Science.gov (United States)

    Rozhkov, Mikhail; Bobrov, Dmitry; Kitov, Ivan

    2014-05-01

    The Master Event technique is a powerful tool for Expert Technical Analysis within the CTBT framework as well as for real-time monitoring with the waveform cross-correlation (CC) (match filter) approach. The primary goal of CTBT monitoring is detection and location of nuclear explosions. Therefore, the cross-correlation monitoring should be focused on finding such events. The use of physically adequate waveform templates may significantly increase the number of valid, both natural and manmade, events in the Reviewed Event Bulletin (REB) of the International Data Centre. Inadequate templates for master events may increase the number of CTBT irrelevant events in REB and reduce the sensitivity of the CC technique to valid events. In order to cover the entire earth, including vast aseismic territories, with the CC based nuclear test monitoring we conducted a thorough research and defined the most appropriate real and synthetic master events representing underground explosion sources. A procedure was developed on optimizing the master event template simulation and narrowing the classes of CC templates used in detection and location process based on principal and independent component analysis (PCA and ICA). Actual waveforms and metadata from the DTRA Verification Database were used to validate our approach. The detection and location results based on real and synthetic master events were compared. The prototype of CC-based Global Grid monitoring system developed in IDC during last year was populated with different hybrid waveform templates (synthetics, synthetics components, and real components) and its performance was assessed with the world seismicity data flow, including the DPRK-2013 event. The specific features revealed in this study for the P-waves from the DPRK underground nuclear explosions (UNEs) can reduce the global detection threshold of seismic monitoring under the CTBT by 0.5 units of magnitude. This corresponds to the reduction in the test yield by a

  15. Genetic algorithms optimization of photonic crystal fibers for half diffraction angle reduction of output beam.

    Science.gov (United States)

    Lu, Jyun-Hong; Cai, Dong-Po; Tsai, Ya-Lun; Chen, Chii-Chang; Lin, Chu-En; Yen, Ta-Jen

    2014-09-22

    In this work, we optimize the structure of the photonic crystal fibers by using genetic algorithms to provide strong light confinement in fiber and small half diffraction angle of output beam. Furthermore, this article shows the potentials of this study, such as optimizing three purposes at the same time and the arbitrary structure design is achieved. We report two optimized results obtained by different optimization conditions. The results show that the half diffraction angle of the output beam of the photonic crystal fibers can be reduced.

  16. Reactive transport modelling of biogeochemical processes and carbon isotope geochemistry inside a landfill leachate plume.

    Science.gov (United States)

    van Breukelen, Boris M; Griffioen, Jasper; Röling, Wilfred F M; van Verseveld, Henk W

    2004-06-01

    The biogeochemical processes governing leachate attenuation inside a landfill leachate plume (Banisveld, the Netherlands) were revealed and quantified using the 1D reactive transport model PHREEQC-2. Biodegradation of dissolved organic carbon (DOC) was simulated assuming first-order oxidation of two DOC fractions with different reactivity, and was coupled to reductive dissolution of iron oxide. The following secondary geochemical processes were required in the model to match observations: kinetic precipitation of calcite and siderite, cation exchange, proton buffering and degassing. Rate constants for DOC oxidation and carbonate mineral precipitation were determined, and other model parameters were optimized using the nonlinear optimization program PEST by means of matching hydrochemical observations closely (pH, DIC, DOC, Na, K, Ca, Mg, NH4, Fe(II), SO4, Cl, CH4, saturation index of calcite and siderite). The modelling demonstrated the relevance and impact of various secondary geochemical processes on leachate plume evolution. Concomitant precipitation of siderite masked the act of iron reduction. Cation exchange resulted in release of Fe(II) from the pristine anaerobic aquifer to the leachate. Degassing, triggered by elevated CO2 pressures caused by carbonate precipitation and proton buffering at the front of the plume, explained the observed downstream decrease in methane concentration. Simulation of the carbon isotope geochemistry independently supported the proposed reaction network.

  17. OPtimal backlight scanning for 3D crosstalk reduction in LCD TV

    DEFF Research Database (Denmark)

    Burini, Nino; Shu, Xiao; Jiao, Liangbao

    2013-01-01

    This work presents a method to determine the optimal backlight scanning signals to minimize crosstalk for time-sequential stereoscopic 3D on LCD TV with active shutter glasses. The solution is obtained through optimization of the variables defined by a model of backlight scanning that considers...

  18. Reduction method with system analysis for multiobjective optimization-based design

    Science.gov (United States)

    Azarm, S.; Sobieszczanski-Sobieski, J.

    1993-01-01

    An approach for reducing the number of variables and constraints, which is combined with System Analysis Equations (SAE), for multiobjective optimization-based design is presented. In order to develop a simplified analysis model, the SAE is computed outside an optimization loop and then approximated for use by an operator. Two examples are presented to demonstrate the approach.

  19. Reduction of shock induced noise in imperfectly expanded supersonic jets using convex optimization

    Science.gov (United States)

    Adhikari, Sam

    2007-11-01

    Imperfectly expanded jets generate screech noise. The imbalance between the backpressure and the exit pressure of the imperfectly expanded jets produce shock cells and expansion or compression waves from the nozzle. The instability waves and the shock cells interact to generate the screech sound. The mathematical model consists of cylindrical coordinate based full Navier-Stokes equations and large-eddy-simulation turbulence modeling. Analytical and computational analysis of the three-dimensional helical effects provide a model that relates several parameters with shock cell patterns, screech frequency and distribution of shock generation locations. Convex optimization techniques minimize the shock cell patterns and the instability waves. The objective functions are (convex) quadratic and the constraint functions are affine. In the quadratic optimization programs, minimization of the quadratic functions over a set of polyhedrons provides the optimal result. Various industry standard methods like regression analysis, distance between polyhedra, bounding variance, Markowitz optimization, and second order cone programming is used for Quadratic Optimization.

  20. OPTIMIZATION METHOD AND SOFTWARE FOR FUEL COST REDUCTION IN CASE OF ROAD TRANSPORT ACTIVITY

    Directory of Open Access Journals (Sweden)

    György Kovács

    2017-06-01

    Full Text Available The transport activity is one of the most expensive processes in the supply chain and the fuel cost is the highest cost among the cost components of transportation. The goal of the research is to optimize the transport costs in case of a given transport task both by the selecting the optimal petrol station and by determining the optimal amount of the refilled fuel. Recently, in practice, these two decisions have not been made centrally at the forwarding company, but they depend on the individual decision of the driver. The aim of this study is to elaborate a precise and reliable mathematical method for selecting the optimal refuelling stations and determining the optimal amount of the refilled fuel to fulfil the transport demands. Based on the elaborated model, new decision-supporting software is developed for the economical fulfilment of transport trips.

  1. SVD-based optimal filtering for noise reduction in dual microphone hearing aids: a real time implementation and perceptual evaluation.

    Science.gov (United States)

    Maj, Jean-Baptiste; Royackers, Liesbeth; Moonen, Marc; Wouters, Jan

    2005-09-01

    In this paper, the first real-time implementation and perceptual evaluation of a singular value decomposition (SVD)-based optimal filtering technique for noise reduction in a dual microphone behind-the-ear (BTE) hearing aid is presented. This evaluation was carried out for a speech weighted noise and multitalker babble, for single and multiple jammer sound source scenarios. Two basic microphone configurations in the hearing aid were used. The SVD-based optimal filtering technique was compared against an adaptive beamformer, which is known to give significant improvements in speech intelligibility in noisy environment. The optimal filtering technique works without assumptions about a speaker position, unlike the two-stage adaptive beamformer. However this strategy needs a robust voice activity detector (VAD). A method to improve the performance of the VAD was presented and evaluated physically. By connecting the VAD to the output of the noise reduction algorithms, a good discrimination between the speech-and-noise periods and the noise-only periods of the signals was obtained. The perceptual experiments demonstrated that the SVD-based optimal filtering technique could perform as well as the adaptive beamformer in a single noise source scenario, i.e., the ideal scenario for the latter technique, and could outperform the adaptive beamformer in multiple noise source scenarios.

  2. Searching for Biogeochemical Cycles on Mars

    Science.gov (United States)

    DesMarais, David J.

    1997-01-01

    The search for life on Mars clearly benefits from a rigorous, yet broad, definition of life that compels us to consider all possible lines of evidence for a martian biosphere. Recent studies in microbial ecology illustrate that the classic definition of life should be expanded beyond the traditional definition of a living cell. The traditional defining characteristics of life are threefold. First, life is capable of metabolism, that is, it performs chemical reactions that utilize energy and also synthesize its cellular constituents. Second, life is capable of self-replication. Third, life can evolve in order to adapt to environmental changes. An expanded, ecological definition of life also recognizes that life is a community of organisms that must interact with their nonliving environment through processes called biogeochemical cycles. This regenerative processing maintains, in an aqueous conditions, a dependable supply of nutrients and energy for growth. In turn, life can significantly affect those processes that control the exchange of materials between the atmosphere, ocean, and upper crust. Because metabolic processes interact directly with the environment, they can alter their surroundings and thus leave behind evidence of life. For example, organic matter is produced from single-carbon-atom precursors for the biosynthesis of cellular constituents. This leads to a reservoir of reduced carbon in sediments that, in turn, can affect the oxidation state of the atmosphere. The harvesting of chemical energy for metabolism often employs oxidation-reduction reactions that can alter the chemistry and oxidation state of the redox-sensitive elements carbon, sulfur, nitrogen, iron, and manganese. Have there ever been biogeochemical cycles on Mars? Certain key planetary processes can offer clues. Active volcanism provides reduced chemical species that biota can use for organic synthesis. Volcanic carbon dioxide and methane can serve as greenhouse gases. Thus the

  3. Searching for Biogeochemical Cycles on Mars

    Science.gov (United States)

    DesMarais, David J.

    1997-01-01

    The search for life on Mars clearly benefits from a rigorous, yet broad, definition of life that compels us to consider all possible lines of evidence for a martian biosphere. Recent studies in microbial ecology illustrate that the classic definition of life should be expanded beyond the traditional definition of a living cell. The traditional defining characteristics of life are threefold. First, life is capable of metabolism, that is, it performs chemical reactions that utilize energy and also synthesize its cellular constituents. Second, life is capable of self-replication. Third, life can evolve in order to adapt to environmental changes. An expanded, ecological definition of life also recognizes that life is a community of organisms that must interact with their nonliving environment through processes called biogeochemical cycles. This regenerative processing maintains, in an aqueous conditions, a dependable supply of nutrients and energy for growth. In turn, life can significantly affect those processes that control the exchange of materials between the atmosphere, ocean, and upper crust. Because metabolic processes interact directly with the environment, they can alter their surroundings and thus leave behind evidence of life. For example, organic matter is produced from single-carbon-atom precursors for the biosynthesis of cellular constituents. This leads to a reservoir of reduced carbon in sediments that, in turn, can affect the oxidation state of the atmosphere. The harvesting of chemical energy for metabolism often employs oxidation-reduction reactions that can alter the chemistry and oxidation state of the redox-sensitive elements carbon, sulfur, nitrogen, iron, and manganese. Have there ever been biogeochemical cycles on Mars? Certain key planetary processes can offer clues. Active volcanism provides reduced chemical species that biota can use for organic synthesis. Volcanic carbon dioxide and methane can serve as greenhouse gases. Thus the

  4. Optimizing Blocking and Nonblocking Reduction Operations for Multicore Systems: Hierarchical Design and Implementation

    Energy Technology Data Exchange (ETDEWEB)

    Gorentla Venkata, Manjunath [ORNL; Shamis, Pavel [ORNL; Graham, Richard L [ORNL; Ladd, Joshua S [ORNL; Sampath, Rahul S [ORNL

    2013-01-01

    Many scientific simulations, using the Message Passing Interface (MPI) programming model, are sensitive to the performance and scalability of reduction collective operations such as MPI Allreduce and MPI Reduce. These operations are the most widely used abstractions to perform mathematical operations over all processes that are part of the simulation. In this work, we propose a hierarchical design to implement the reduction operations on multicore systems. This design aims to improve the efficiency of reductions by 1) tailoring the algorithms and customizing the implementations for various communication mechanisms in the system 2) providing the ability to configure the depth of hierarchy to match the system architecture, and 3) providing the ability to independently progress each of this hierarchy. Using this design, we implement MPI Allreduce and MPI Reduce operations (and its nonblocking variants MPI Iallreduce and MPI Ireduce) for all message sizes, and evaluate on multiple architectures including InfiniBand and Cray XT5. We leverage and enhance our existing infrastructure, Cheetah, which is a framework for implementing hierarchical collective operations to implement these reductions. The experimental results show that the Cheetah reduction operations outperform the production-grade MPI implementations such as Open MPI default, Cray MPI, and MVAPICH2, demonstrating its efficiency, flexibility and portability. On Infini- Band systems, with a microbenchmark, a 512-process Cheetah nonblocking Allreduce and Reduce achieves a speedup of 23x and 10x, respectively, compared to the default Open MPI reductions. The blocking variants of the reduction operations also show similar performance benefits. A 512-process nonblocking Cheetah Allreduce achieves a speedup of 3x, compared to the default MVAPICH2 Allreduce implementation. On a Cray XT5 system, a 6144-process Cheetah Allreduce outperforms the Cray MPI by 145%. The evaluation with an application kernel, Conjugate

  5. Optimizing Fire Department Operations Through Work Schedule Analysis, Alternative Staffing, and Nonproductive Time Reduction

    Science.gov (United States)

    2014-09-01

    Fire Rescue,” St. Anthony Hospitals, October 2006. 17 Leeanna Mims , “Overtime Cost Reduction with Alternative Work Schedules” Executive Fire Officer...Effectiveness: 24-hour schedules may lead to sleep deprivation when an employee’s cognitive skills are inhibited.50 Sleep deprivation may result 48 Mims ...Consecutive Hour Work Limit.” 56 Mims , “Overtime Cost Reduction with Alternative Work Schedules.” 37

  6. Study on Reduction of Cogging Torque fir BLDC Motor Using Response Surface Methodology Optimization

    Energy Technology Data Exchange (ETDEWEB)

    A Kim, Young Kyoun [Changwon National University, Changwon(Korea); Lee, Geun Ho; Hong, Jung Pyo [Hanyang University, Seoul(Korea)

    2002-02-01

    This paper presents an optimization procedure by using Response Surface Methodology(RSM) to determine design parameters for for reducing cogging torque. RSM is achieved through using the experimental design method in combination with Finite Element Method and adapted to make analytical model for a complex problem considering a lot of interaction of these parameters. Sequential Quadratic Problem (SQP) method is used to solve the resulting of constrained nonlinear optimization problem. (author). 9 refs., 4 figs., 4 tabs.

  7. Evolutionary optimization for conditions of variable BHF for springback reduction in AHSS-mild steel TWB

    Science.gov (United States)

    Nguyen, N.-T.; Chakraborti, N.; Barlat, F.

    2013-12-01

    In this study, the advanced high strength steels (AHSS)/mild steel TWB sheet is applied to the U-draw bending springback under non-constant blank holding force (BHF). On both sides of the blank, two different BHF-punch stroke are applied. A systematic approach to obtain optimal BHF-stroke profiles is proposed. The optimal condition would require satisfying two conflicting objectives simultaneously: (1) minimize springback deformation and (2) minimize the forming severity, leading to a Pareto-optimal problem. The optimization procedure consists of the following steps: sampling design, finite element (FE) simulations, metamodeling, and finally the calculation of a Pareto-frontier. PAM-STAMP® FE software is employed in this study. The generated outputs of FE simulations on some statistically significant sampling points are then used for the construction of metamodels of optimum accuracy and complexity, which, in turn, were used to evaluate the output for any set of inputs, replacing the computing intensive FE simulations. A novel genetic algorithms based multi-objective optimization technique is applied for optimization. Yet far to be completely removed, springback in TWB can be appreciably reduced using the proposed approach of variable BHF control.

  8. Hyporheic zone as a bioreactor: sediment heterogeneity influencing biogeochemical processes

    Science.gov (United States)

    Perujo, Nuria; Romani, Anna M.; Sanchez-Vila, Xavier

    2017-04-01

    Mediterranean fluvial systems are characterized by frequent periods of low flow or even drought. During low flow periods, water from wastewater treatment plants (WWTPs) is proportionally large in fluvial systems. River water might be vertically transported through the hyporheic zone, and then porous medium acts as a complementary treatment system since, as water infiltrates, a suite of biogeochemical processes occurs. Subsurface sediment heterogeneity plays an important role since it influences the interstitial fluxes of the medium and drives biomass growing, determining biogeochemical reactions. In this study, WWTP water was continuously infiltrated for 3 months through two porous medium tanks: one consisting of 40 cm of fine sediment (homogeneous); and another comprised of two layers of different grain size sediments (heterogeneous), 20 cm of coarse sediment in the upper part and 20 cm of fine one in the bottom. Several hydrological, physicochemical and biological parameters were measured periodically (weekly at the start of the experiment and biweekly at the end). Analysed parameters include dissolved nitrogen, phosphorus, organic carbon, and oxygen all measured at the surface, and at 5, 20 and 40 cm depth. Variations in hydraulic conductivity with time were evaluated. Sediment samples were also analysed at three depths (surface, 20 and 40 cm) to determine bacterial density, chlorophyll content, extracellular polymeric substances, and biofilm function (extracellular enzyme activities and carbon substrate utilization profiles). Preliminary results suggest hydraulic conductivity to be the main driver of the differences in the biogeochemical processes occurring in the subsurface. At the heterogeneous tank, a low nutrient reduction throughout the whole medium is measured. In this medium, high hydraulic conductivity allows for a large amount of infiltrating water, but with a small residence time. Since some biological processes are largely time-dependent, small water

  9. Trajectory Optimization for Velocity Jumps Reduction considering the Unexpectedness Characteristics of Space Manipulator Joint-Locked Failure

    Directory of Open Access Journals (Sweden)

    Qingxuan Jia

    2016-01-01

    Full Text Available Aiming at reducing joint velocity jumps caused by an unexpected joint-locked failure during space manipulator on-orbit operations without shutting down manipulator, trajectory optimization strategy considering the unexpectedness characteristics of joint-locked failure is proposed in the paper, which can achieve velocity jumps reduction in both operation space and joint space simultaneously. In the strategy, velocity in operation space concerning task completion directly is treated as equality constraints, and velocity in joint space concerning motion performance is treated as objective function. Global compensation vector which consists of coefficient, gradient of manipulability, and orthogonal matrix of null space is constructed to minimize the objective function. For each particular failure time, unique optimal coefficient can be obtained when the objective function is minimal. As a basis, a method for optimal coefficient function fitting is proposed based on a priori failure information (possible failure time and the corresponding optimal coefficient to guarantee the unexpectedness characteristics of joint-locked failure. Simulations are implemented to validate the efficiency of trajectory optimization strategy in reducing velocity jumps in both joint space and operation space. And the feasibility of coefficient function is also verified in reducing velocity jump no matter when joint-locked failure occurs.

  10. Calibrating a global three-dimensional biogeochemical ocean model (MOPS-1.0)

    Science.gov (United States)

    Kriest, Iris; Sauerland, Volkmar; Khatiwala, Samar; Srivastav, Anand; Oschlies, Andreas

    2017-01-01

    Global biogeochemical ocean models contain a variety of different biogeochemical components and often much simplified representations of complex dynamical interactions, which are described by many ( ≈ 10 to ≈ 100) parameters. The values of many of these parameters are empirically difficult to constrain, due to the fact that in the models they represent processes for a range of different groups of organisms at the same time, while even for single species parameter values are often difficult to determine in situ. Therefore, these models are subject to a high level of parametric uncertainty. This may be of consequence for their skill with respect to accurately describing the relevant features of the present ocean, as well as their sensitivity to possible environmental changes. We here present a framework for the calibration of global biogeochemical ocean models on short and long timescales. The framework combines an offline approach for transport of biogeochemical tracers with an estimation of distribution algorithm (Covariance Matrix Adaption Evolution Strategy, CMA-ES). We explore the performance and capability of this framework by five different optimizations of six biogeochemical parameters of a global biogeochemical model, simulated over 3000 years. First, a twin experiment explores the feasibility of this approach. Four optimizations against a climatology of observations of annual mean dissolved nutrients and oxygen determine the extent to which different setups of the optimization influence model fit and parameter estimates. Because the misfit function applied focuses on the large-scale distribution of inorganic biogeochemical tracers, parameters that act on large spatial and temporal scales are determined earliest, and with the least spread. Parameters more closely tied to surface biology, which act on shorter timescales, are more difficult to determine. In particular, the search for optimum zooplankton parameters can benefit from a sound knowledge of

  11. Towards Energy Demand Reduction in Social Housing Buildings: Envelope System Optimization Strategies

    Directory of Open Access Journals (Sweden)

    Paula M. Esquivias

    2012-07-01

    Full Text Available This work evaluates the potential for the reduction of energy demand in residential buildings by acting on the exterior envelope, both in newly constructed buildings and in the retrofitting of existing stock. It focuses on analysing social housing buildings in Mediterranean areas and on quantifying the scope of that reduction in the application of different envelope design strategies, with the purpose of prioritizing their application based on their energy efficiency. The analyses and quantifications were made by means of the generation of energy models with the TRNSYS tool for simple or combined solutions, identifying possible potentials for reduction of the energy demand from 20% to 25%, basically by acting on the windows. The case study was a newly built social housing building of a closed block type located in Seville (Spain. Its constructive techniques and the insulation level of its envelope are standardized for current buildings widespread across Mediterranean Europe.

  12. Optimal Allocation of Distributed Generation and Capacitor Banks in Order to Loss Reduction in Reconfigured System

    Directory of Open Access Journals (Sweden)

    Noradin Ghadimi

    2012-01-01

    Full Text Available The concern about the limitation of fossil fuels and also rising consciousness of environmental protection, cause the installation of DGs increase annually. This study develops an optimal placement method in order to sizing and sitting of distributed generation and capacitor banks in IEEE 33 bus test system that reconfigured. The algorithm for optimization in this paper is simulated annealing. The proposed objective function considers active power losses of the system and the voltage profile in nominal load of system. High performance of the proposed algorithm in mention system is verified by simulations in MATLAB software and in order to illustrate of feasibility of proposed method this optimization will accomplish in two cases.

  13. Sensitivity analysis and parameter optimization for vibration reduction of undamped multi-ribbed belt drive systems

    Science.gov (United States)

    Hou, Zhi-chao; Lao, Yao-xin; Lu, Qiu-hai

    2008-11-01

    Tensioner is a critical mechanism to ensure a constant tension level within a serpentine belt drive that is widely used in modern passenger vehicles. For a belt drive with n pulleys, generic and explicit formulae about sensitivities of both frequency and steady harmonic responses are established in terms of system matrices with respect to any design parameter of the system. Deductions from the formulae results in frequency and steady response sensitivities relative to key tensioner parameters and the belt speed. Based on sensitivity analysis, optimizations are conducted on tensioner so as to suppress dynamic responses of the system by frequency detuning. A new approach for searching optimal parameters is put forward by incorporating sensitivity information into a classical coordinate alternating procedure. Examples are given to validate the analytical formulae of the frequency sensitivity and to demonstrate the effect of optimization.

  14. Reduction of Key Search Space of Vigenere Cipher Using Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Ganapathi Sivagurunathan

    2011-01-01

    Full Text Available Problem statement: With the demand for effective network security is increasing, it becomes necessary to find the strength and weaknesses of the existing cryptographic methods. Vigenere cipher, a classical cipher is analyzed for its strength against a cipher only attack. Approach: The cipher texts so selected were of various sizes up to 1 Kb. A biologically inspired algorithm, Particle Swarm Optimization (PSO was applied to the problem of crypt analyzing the Vigenere cipher. PSO was an optimization technique and its used on the problem of optimizing the fitness function designed for Vigenere cipher was performed. Results: It was seen that PSO is able to find the keyword employed and the other possible combinations for the keyword. Conclusion: PSO is better than genetic algorithm to solve Vigenere cipher and can be used to find the keyword with lesser size.

  15. Automatic assist feature placement optimization based on process-variability reduction

    Science.gov (United States)

    Jayaram, Srividya; Yehia, Ayman; Bahnas, Mohamed; Maaty Omar, Hesham A.; Bozkus, Zeki; Sturtevant, John L.

    2007-10-01

    To maximize the process window and CD control of main features, sizing and placement rules for sub-resolution assist features (SRAF) need to be optimized, subject to the constraint that the SRAFs not print through the process window. With continuously shrinking target dimensions, generation of traditional rule-based SRAFs is becoming an expensive process in terms of time, cost and complexity. This has created an interest in other rule optimization methodologies, such as image contrast and other edge- and image-based objective functions. In this paper, we propose using an automated model-based flow to obtain the optimal SRAF insertion rules for a design and reduce the time and effort required to define the best rules. In this automated flow, SRAF placement is optimized by iteratively generating the space-width rules and assessing their performance against process variability metrics. Multiple metrics are used in the flow. Process variability (PV) band thickness is a good indicator of the process window enhancement. Depth of focus (DOF), the total range of focus that can be tolerated, is also a highly descriptive metric for the effectiveness of the sizing and placement rules generated. Finally, scatter bar (SB) printing margin calculations assess the allowed exposure range that prevents scatter bars from printing on the wafer.

  16. Optimal placement of water-lubricated rubber bearings for vibration reduction of flexible multistage rotor systems

    Science.gov (United States)

    Liu, Shibing; Yang, Bingen

    2017-10-01

    Flexible multistage rotor systems with water-lubricated rubber bearings (WLRBs) have a variety of engineering applications. Filling a technical gap in the literature, this effort proposes a method of optimal bearing placement that minimizes the vibration amplitude of a WLRB-supported flexible rotor system with a minimum number of bearings. In the development, a new model of WLRBs and a distributed transfer function formulation are used to define a mixed continuous-and-discrete optimization problem. To deal with the case of uncertain number of WLRBs in rotor design, a virtual bearing method is devised. Solution of the optimization problem by a real-coded genetic algorithm yields the locations and lengths of water-lubricated rubber bearings, by which the prescribed operational requirements for the rotor system are satisfied. The proposed method is applicable either to preliminary design of a new rotor system with the number of bearings unforeknown or to redesign of an existing rotor system with a given number of bearings. Numerical examples show that the proposed optimal bearing placement is efficient, accurate and versatile in different design cases.

  17. Ultra-broadband Reflective Metamaterial with RCS Reduction based on Polarization Convertor, Information Entropy Theory and Genetic Optimization Algorithm

    Science.gov (United States)

    Li, Si Jia; Cao, Xiang Yu; Xu, Li Ming; Zhou, Long Jian; Yang, Huan Huan; Han, Jiang Feng; Zhang, Zhao; Zhang, Di; Liu, Xiao; Zhang, Chen; Zheng, Yue Jun; Zhao, Yi

    2016-11-01

    We proposed an ultra-broadband reflective metamaterial with controlling the scattering electromagnetic fields based on a polarization convertor. The unit cell of the polarization convertor was composed of a three layers substrate with double metallic split-rings structure and a metal ground plane. The proposed polarization convertor and that with rotation angle of 90 deg had been employed as the “0” and “1” elements to design the digital reflective metamaterial. The numbers of the “0” and “1” elements were chosen based on the information entropy theory. Then, the optimized combinational format was selected by genetic optimization algorithm. The scattering electromagnetic fields had been manipulated due to destructive interference, which was attributed to the control of phase and amplitude by the proposed polarization convertor. Simulated and experimental results indicated that the reflective metamaterial exhibited significantly RCS reduction in an ultra-broad frequency band for both normal and oblique incidences.

  18. Optimizing tuning masses for helicopter rotor blade vibration reduction including computed airloads and comparison with test data

    Science.gov (United States)

    Pritchard, Jocelyn I.; Adelman, Howard M.; Walsh, Joanne L.; Wilbur, Matthew L.

    1992-01-01

    An optimization procedure is developed for locating tuning masses on a rotor blade so that vibratory loads are minimized and hub-shear harmonics are reduced without adding a large mass penalty. The airloads are computed by means of a helicopter analysis for the cases of three vs six tuning masses, with attention given to the prediction of changes in airloads. Frequencies, airloads, and hub loads are computed with the CAMRAD/JA helicopter analysis code and the Conmin general-purpose optimization program. The hub shear is found to be significantly reduced in both cases with the added mass, and the reduction of hub shear is demonstrated under three flight conditions. Comparisons with wind-tunnel data demonstrate that the correlation of mass location is good and the relationship between mass location and flight speed is predicted well by the model.

  19. Optimization of Manganese Reduction in Biotreated POME onto 3A Molecular Sieve and Clinoptilolite Zeolites.

    Science.gov (United States)

    Jami, Mohammed S; Rosli, Nurul-Shafiqah; Amosa, Mutiu K

    2016-06-01

    Availability of quality-certified water is pertinent to the production of food and pharmaceutical products. Adverse effects of manganese content of water on the corrosion of vessels and reactors necessitate that process water is scrutinized for allowable concentration levels before being applied in the production processes. In this research, optimization of the adsorption process conditions germane to the removal of manganese from biotreated palm oil mill effluent (BPOME) using zeolite 3A subsequent to a comparative adsorption with clinoptilolite was studied. A face-centered central composite design (FCCCD) of the response surface methodology (RSM) was adopted for the study. Analysis of variance (ANOVA) for response surface quadratic model revealed that the model was significant with dosage and agitation speed connoting the main significant process factors for the optimization. R(2) of 0.9478 yielded by the model was in agreement with predicted R(2). Langmuir and pseudo-second-order suggest the adsorption mechanism involved monolayer adsorption and cation exchanging.

  20. Proton energy optimization and reduction for intensity-modulated proton therapy

    Science.gov (United States)

    Cao, Wenhua; Lim, Gino; Liao, Li; Li, Yupeng; Jiang, Shengpeng; Li, Xiaoqiang; Li, Heng; Suzuki, Kazumichi; Zhu, X. Ronald; Gomez, Daniel; Zhang, Xiaodong

    2014-10-01

    Intensity-modulated proton therapy (IMPT) is commonly delivered via the spot-scanning technique. To ‘scan’ the target volume, the proton beam is controlled by varying its energy to penetrate the patient’s body at different depths. Although scanning the proton beamlets or spots with the same energy can be as fast as 10-20 m s-1, changing from one proton energy to another requires approximately two additional seconds. The total IMPT delivery time thus depends mainly on the number of proton energies used in a treatment. Current treatment planning systems typically use all proton energies that are required for the proton beam to penetrate in a range from the distal edge to the proximal edge of the target. The optimal selection of proton energies has not been well studied. In this study, we sought to determine the feasibility of optimizing and reducing the number of proton energies in IMPT planning. We proposed an iterative mixed-integer programming optimization method to select a subset of all available proton energies while satisfying dosimetric criteria. We applied our proposed method to six patient datasets: four cases of prostate cancer, one case of lung cancer, and one case of mesothelioma. The numbers of energies were reduced by 14.3%-18.9% for the prostate cancer cases, 11.0% for the lung cancer cases and 26.5% for the mesothelioma case. The results indicate that the number of proton energies used in conventionally designed IMPT plans can be reduced without degrading dosimetric performance. The IMPT delivery efficiency could be improved by energy layer optimization leading to increased throughput for a busy proton center in which a delivery system with slow energy switch is employed.

  1. Shape Optimization of Three-Way Reversing Valve for Cavitation Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myeong Gon; Han, Seung Ho [Donga Univ., Busan (Korea, Republic of); Lim, Cha Suk [Baek San Hi-Tech Co., Ltd., Seoul (Korea, Republic of)

    2015-11-15

    A pair of two-way valves typically is used in automotive washing machines, where the water flow direction is frequently reversed and highly pressurized clean water is sprayed to remove the oil and dirt remaining on machined engine and transmission blocks. Although this valve system has been widely used because of its competitive price, its application is sometimes restricted by surging effects, such as pressure ripples occurring in rapid changes in water flow caused by inaccurate valve control. As an alternative, one three-way reversing valve can replace the valve system because it provides rapid and accurate changes to the water flow direction without any precise control device. However, a cavitation effect occurs because of the complicated bottom plug shape of the valve. In this study, the cavitation index and percent of cavitation (POC) were introduced to numerically evaluate fluid flows via computational fluid dynamics (CFD) analysis. To reduce the cavitation effect generated by the bottom plug, the optimal shape design was carried out through a parametric study, in which a simple computer-aided engineering (CAE) model was applied to avoid time consuming CFD analysis and difficulties in achieving convergence. The optimal shape design process using full factorial design of experiments (DOEs) and an artificial neural network meta-model yielded the optimal waist and tail length of the bottom plug with a POC value of less than 30%, which meets the requirement of no cavitation occurrence. The optimal waist length, tail length and POC value were found to 6.42 mm, 6.96 mm and 27%, respectively.

  2. Shape optimization of three-way reversing valve for cavitation reduction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Myeong Gon; Han, Seung Ho [Dept. of Mechanical Engineering, Dong-A University, Busan (Korea, Republic of); Lim, Cha Suk [Baek San Hi-Tech Co., Ltd., Yangsan(Korea, Republic of)

    2015-11-15

    A pair of two-way valves typically is used in automotive washing machines, where the water flow direction is frequently reversed and highly pressurized clean water is sprayed to remove the oil and dirt remaining on machined engine and transmission blocks. Although this valve system has been widely used because of its competitive price, its application is sometimes restricted by surging effects, such as pressure ripples occurring in rapid changes in water flow caused by inaccurate valve control. As an alternative, one three-way reversing valve can replace the valve system because it provides rapid and accurate changes to the water flow direction without any precise control device. However, a cavitation effect occurs because of the complicated bottom plug shape of the valve. In this study, the cavitation index and percent of cavitation (POC) were introduced to numerically evaluate fluid flows via computational fluid dynamics (CFD) analysis. To reduce the cavitation effect generated by the bottom plug, the optimal shape design was carried out through a parametric study, in which a simple computer-aided engineering (CAE) model was applied to avoid time-consuming CFD analysis and difficulties in achieving convergence. The optimal shape design process using full factorial design of experiments (DOEs) and an artificial neural network meta-model yielded the optimal waist and tail length of the bottom plug with a POC value of less than 30%, which meets the requirement of no cavitation occurrence. The optimal waist length, tail length and POC value were found to 6.42 mm, 6.96 mm and 27%, respectively.

  3. Optimization of Variable-Depth Liner Configurations for Increased Broadband Noise Reduction

    Science.gov (United States)

    Jones, M. G.; Watson, W. R.; Nark, D. M.; Schiller, N. H.; Born, J. C.

    2016-01-01

    This paper employs three acoustic propagation codes to explore variable-depth liner configurations for the NASA Langley Grazing Flow Impedance Tube (GFIT). The initial study demonstrates that a variable impedance can acceptably be treated as a uniform impedance if the spatial extent over which this variable impedance occurs is less than one-third of a wavelength of the incident sound. A constrained optimization study is used to design a variable-depth liner and to select an optimization metric. It also provides insight regarding how much attenuation can be achieved with variable-depth liners. Another optimization study is used to design a liner with much finer chamber depth resolution for the Mach 0.0 and 0.3 test conditions. Two liners are designed based on spatial rearrangement of chambers from this liner to determine whether the order is critical. Propagation code predictions suggest this is not the case. Both liners are fabricated via additive manufacturing and tested in the GFIT for the Mach 0.0 condition. Predicted and measured attenuations compare favorably across the full frequency range. These results clearly suggest that the chambers can be arranged in any order, thus offering the potential for innovative liner designs to minimize depth and weight.

  4. Correlating phospholipid fatty acids (PLFA) in a landfill leachate polluted aquifer with biogeochemical factors by multivariate statistical methods

    DEFF Research Database (Denmark)

    Ludvigsen, Liselotte; Albrechtsen, Hans-Jørgen; Rootzén, Helle

    1997-01-01

    Different multivariate statistical analyses were applied to phospholipid fatty acids representing the biomass composition and to different biogeochemical parameters measured in 37 samples from a landfill contaminated aquifer at Grindsted Landfill (Denmark). Principal component analysis and corres......Different multivariate statistical analyses were applied to phospholipid fatty acids representing the biomass composition and to different biogeochemical parameters measured in 37 samples from a landfill contaminated aquifer at Grindsted Landfill (Denmark). Principal component analysis....... Partial least square analysis related the phospholipid fatty acids data to the biogeochemical parameters assuming linear relationships. After selection of the optimal phospholipid fatty acid combination by genetic algorithms, good partial least squares models with low prediction errors were gained...

  5. Energy Saving Melting and Revert Reduction Technology (E-SMARRT): Design Support for Tooling Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dongtao

    2011-09-23

    High pressure die casting is an intrinsically efficient net shape process and improvements in energy efficiency are strongly dependent on design and process improvements that reduce scrap rates so that more of the total consumed energy goes into acceptable, usable castings. Computer simulation has become widely used within the industry but use is not universal. Further, many key design decisions must be made before the simulation can be run and expense in terms of money and time often limits the number of decision iterations that can be explored. This work continues several years of work creating simple, very fast, design tools that can assist with the early stage design decisions so that the benefits of simulation can be maximized and, more importantly, so that the chances of first shot success are maximized. First shot success and better running processes contributes to less scrap and significantly better energy utilization by the process. This new technology was predicted to result in an average energy savings of 1.83 trillion BTUs/year over a 10 year period. Current (2011) annual energy saving estimates over a ten year period, based on commercial introduction in 2012, a market penetration of 30% by 2015 is 1.89 trillion BTUs/year by 2022. Along with these energy savings, reduction of scrap and improvement in yield will result in a reduction of the environmental emissions associated with the melting and pouring of the metal which will be saved as a result of this technology. The average annual estimate of CO2 reduction per year through 2022 is 0.037 Million Metric Tons of Carbon Equivalent (MM TCE).

  6. Single-Channel Noise Reduction using Unified Joint Diagonalization and Optimal Filtering

    DEFF Research Database (Denmark)

    Nørholm, Sidsel Marie; Benesty, Jacob; Jensen, Jesper Rindom;

    2014-01-01

    In this paper, the important problem of single-channel noise reduction is treated from a new perspective. The problem is posed as a filtering problem based on joint diagonalization of the covariance matrices of the desired and noise signals. More specifically, the eigenvectors from the joint...... diagonalization corresponding to the least significant eigenvalues are used to form a filter, which effectively estimates the noise when applied to the observed signal. This estimate is then subtracted from the observed signal to form an estimate of the desired signal, i.e., the speech signal. In doing this, we...

  7. Optimization research on the concentration field of NO in selective catalytic reduction flue gas denitration system

    Science.gov (United States)

    Zheng, Qingyu; Zhang, Guoqiang; Che, Kai; Shao, Shikuan; Li, Yanfei

    2017-08-01

    Taking 660 MW generator unit denitration system as a study object, an optimization and adjustment method shall be designed to control ammonia slip, i.e. adjust ammonia injection system based on NO concentration distribution at inlet/outlet of the denitration system to make the injected ammonia distribute evenly. The results shows that, this method can effectively improve NO concentration distribution at outlet of the denitration system and decrease ammonia injection amount and ammonia slip concentration. Reduce adverse impact of SCR denitration process on the air preheater to realize safe production by guaranteeing that NO discharge shall reach the standard.

  8. Cretaceous-Palaeogene experiments in Biogeochemical Resilience

    Science.gov (United States)

    Penman, D. E.; Henehan, M. J.; Hull, P. M.; Planavsky, N.; Schmidt, D. N.; Rae, J. W. B.; Thomas, E.; Huber, B. T.

    2015-12-01

    Human activity is altering biogeochemical cycles in the ocean. While ultimately anthropogenic forcings may be brought under control, it is still unclear whether tipping points may exist beyond which human-induced changes to biogeochemical cycles become irreversible. We use the Late Cretaceous and the Cretaceous-Palaeogene (K-Pg) boundary interval as an informative case study. Over this interval, two carbon cycle perturbations (gradual flood basalt volcanism and abrupt bolide impact) occurred within a short time window, allowing us to investigate the resilience of biogeochemical cycles to different pressures applied to the same initial boundary conditions on very different time scales. We demonstrate that relatively gradual emission of CO2 from the Deccan large igneous province was efficiently mitigated within the limits of existing biogeochemical processes. However, the rapid extinction of pelagic calcifying organisms at the K-Pg boundary due to the Chicxulub bolide impact had more profound effects, and caused lasting (> 1 million years) changes to biogeochemical cycles. By combining sedimentological observations with boron isotope-based pH reconstructions over these events, we document two potentially useful partial analogues for best and worst case scenarios for anthropogenic global change. We suggest that if current ocean acidification results in the mass extinction of marine pelagic calcifiers, we may cause profound changes to the Earth system that will persist for 100,000s to millions of years.

  9. Biological/biomedical accelerator mass spectrometry targets. 1. optimizing the CO2 reduction step using zinc dust.

    Science.gov (United States)

    Kim, Seung-Hyun; Kelly, Peter B; Clifford, Andrew J

    2008-10-15

    Biological and biomedical applications of accelerator mass spectrometry (AMS) use isotope ratio mass spectrometry to quantify minute amounts of long-lived radioisotopes such as (14)C. AMS target preparation involves first the oxidation of carbon (in sample of interest) to CO 2 and second the reduction of CO 2 to filamentous, fluffy, fuzzy, or firm graphite-like substances that coat a -400-mesh spherical iron powder (-400MSIP) catalyst. Until now, the quality of AMS targets has been variable; consequently, they often failed to produce robust ion currents that are required for reliable, accurate, precise, and high-throughput AMS for biological/biomedical applications. Therefore, we described our optimized method for reduction of CO 2 to high-quality uniform AMS targets whose morphology we visualized using scanning electron microscope pictures. Key features of our optimized method were to reduce CO 2 (from a sample of interest that provided 1 mg of C) using 100 +/- 1.3 mg of Zn dust, 5 +/- 0.4 mg of -400MSIP, and a reduction temperature of 500 degrees C for 3 h. The thermodynamics of our optimized method were more favorable for production of graphite-coated iron powders (GCIP) than those of previous methods. All AMS targets from our optimized method were of 100% GCIP, the graphitization yield exceeded 90%, and delta (13)C was -17.9 +/- 0.3 per thousand. The GCIP reliably produced strong (12)C (-) currents and accurate and precise F m values. The observed F m value for oxalic acid II NIST SRM deviated from its accepted F m value of 1.3407 by only 0.0003 +/- 0.0027 (mean +/- SE, n = 32), limit of detection of (14)C was 0.04 amol, and limit of quantification was 0.07 amol, and a skilled analyst can prepare as many as 270 AMS targets per day. More information on the physical (hardness/color), morphological (SEMs), and structural (FT-IR, Raman, XRD spectra) characteristics of our AMS targets that determine accurate, precise, and high-hroughput AMS measurement are in the

  10. SVD-Based Optimal Filtering Technique for Noise Reduction in Hearing Aids Using Two Microphones

    Directory of Open Access Journals (Sweden)

    Moonen Marc

    2002-01-01

    Full Text Available We introduce a new SVD-based (Singular value decomposition strategy for noise reduction in hearing aids. This technique is evaluated for noise reduction in a behind-the-ear (BTE hearing aid where two omnidirectional microphones are mounted in an endfire configuration. The behaviour of the SVD-based technique is compared to a two-stage adaptive beamformer for hearing aids developed by Vanden Berghe and Wouters (1998. The evaluation and comparison is done with a performance metric based on the speech intelligibility index (SII. The speech and noise signals are recorded in reverberant conditions with a signal-to-noise ratio of and the spectrum of the noise signals is similar to the spectrum of the speech signal. The SVD-based technique works without initialization nor assumptions about a look direction, unlike the two-stage adaptive beamformer. Still, for different noise scenarios, the SVD-based technique performs as well as the two-stage adaptive beamformer, for a similar filter length and adaptation time for the filter coefficients. In a diffuse noise scenario, the SVD-based technique performs better than the two-stage adaptive beamformer and hence provides a more flexible and robust solution under speaker position variations and reverberant conditions.

  11. SVD-Based Optimal Filtering Technique for Noise Reduction in Hearing Aids Using Two Microphones

    Science.gov (United States)

    Maj, Jean-Baptiste; Moonen, Marc; Wouters, Jan

    2002-12-01

    We introduce a new SVD-based (Singular value decomposition) strategy for noise reduction in hearing aids. This technique is evaluated for noise reduction in a behind-the-ear (BTE) hearing aid where two omnidirectional microphones are mounted in an endfire configuration. The behaviour of the SVD-based technique is compared to a two-stage adaptive beamformer for hearing aids developed by Vanden Berghe and Wouters (1998). The evaluation and comparison is done with a performance metric based on the speech intelligibility index (SII). The speech and noise signals are recorded in reverberant conditions with a signal-to-noise ratio of [InlineEquation not available: see fulltext.] and the spectrum of the noise signals is similar to the spectrum of the speech signal. The SVD-based technique works without initialization nor assumptions about a look direction, unlike the two-stage adaptive beamformer. Still, for different noise scenarios, the SVD-based technique performs as well as the two-stage adaptive beamformer, for a similar filter length and adaptation time for the filter coefficients. In a diffuse noise scenario, the SVD-based technique performs better than the two-stage adaptive beamformer and hence provides a more flexible and robust solution under speaker position variations and reverberant conditions.

  12. Multi-objective optimization of aircraft design for emission and cost reductions

    Institute of Scientific and Technical Information of China (English)

    Wang Yu; Yin Hailian; Zhang Shuai; Yu Xiongqing

    2014-01-01

    Pollutant gases emitted from the civil jet are doing more and more harm to the environ-ment with the rapid development of the global commercial aviation transport. Low environmental impact has become a new requirement for aircraft design. In this paper, estimation method for emis-sion in aircraft conceptual design stage is improved based on the International Civil Aviation Orga-nization (ICAO) aircraft engine emissions databank and the polynomial curve fitting methods. The greenhouse gas emission (CO2 equivalent) per seat per kilometer is proposed to measure the emis-sions. An approximate sensitive analysis and a multi-objective optimization of aircraft design for tradeoff between greenhouse effect and direct operating cost (DOC) are performed with five geom-etry variables of wing configuration and two flight operational parameters. The results indicate that reducing the cruise altitude and Mach number may result in a decrease of the greenhouse effect but an increase of DOC. And the two flight operational parameters have more effects on the emissions than the wing configuration. The Pareto-optimal front shows that a decrease of 29.8%in DOC is attained at the expense of an increase of 10.8%in greenhouse gases.

  13. Multi-objective optimization of aircraft design for emission and cost reductions

    Directory of Open Access Journals (Sweden)

    Wang Yu

    2014-02-01

    Full Text Available Pollutant gases emitted from the civil jet are doing more and more harm to the environment with the rapid development of the global commercial aviation transport. Low environmental impact has become a new requirement for aircraft design. In this paper, estimation method for emission in aircraft conceptual design stage is improved based on the International Civil Aviation Organization (ICAO aircraft engine emissions databank and the polynomial curve fitting methods. The greenhouse gas emission (CO2 equivalent per seat per kilometer is proposed to measure the emissions. An approximate sensitive analysis and a multi-objective optimization of aircraft design for tradeoff between greenhouse effect and direct operating cost (DOC are performed with five geometry variables of wing configuration and two flight operational parameters. The results indicate that reducing the cruise altitude and Mach number may result in a decrease of the greenhouse effect but an increase of DOC. And the two flight operational parameters have more effects on the emissions than the wing configuration. The Pareto-optimal front shows that a decrease of 29.8% in DOC is attained at the expense of an increase of 10.8% in greenhouse gases.

  14. Optimization-based reconstruction for reduction of CBCT artifact in IGRT

    Science.gov (United States)

    Xia, Dan; Zhang, Zheng; Paysan, Pascal; Seghers, Dieter; Brehm, Marcus; Munro, Peter; Sidky, Emil Y.; Pelizzari, Charles; Pan, Xiaochuan

    2016-04-01

    Kilo-voltage cone-beam computed tomography (CBCT) plays an important role in image guided radiation therapy (IGRT) by providing 3D spatial information of tumor potentially useful for optimizing treatment planning. In current IGRT CBCT system, reconstructed images obtained with analytic algorithms, such as FDK algorithm and its variants, may contain artifacts. In an attempt to compensate for the artifacts, we investigate optimization-based reconstruction algorithms such as the ASD-POCS algorithm for potentially reducing arti- facts in IGRT CBCT images. In this study, using data acquired with a physical phantom and a patient subject, we demonstrate that the ASD-POCS reconstruction can significantly reduce artifacts observed in clinical re- constructions. Moreover, patient images reconstructed by use of the ASD-POCS algorithm indicate a contrast level of soft-tissue improved over that of the clinical reconstruction. We have also performed reconstructions from sparse-view data, and observe that, for current clinical imaging conditions, ASD-POCS reconstructions from data collected at one half of the current clinical projection views appear to show image quality, in terms of spatial and soft-tissue-contrast resolution, higher than that of the corresponding clinical reconstructions.

  15. Optimal Energy Reduction Schedules for Ice Storage Air-Conditioning Systems

    Directory of Open Access Journals (Sweden)

    Whei-Min Lin

    2015-09-01

    Full Text Available This paper proposes a hybrid algorithm to solve the optimal energy dispatch of an ice storage air-conditioning system. Based on a real air-conditioning system, the data, including the return temperature of chilled water, the supply temperature of chilled water, the return temperature of ice storage water, and the supply temperature of ice storage water, are measured. The least-squares regression (LSR is used to obtain the input-output (I/O curve for the cooling load and power consumption of chillers and ice storage tank. The objective is to minimize overall cost in a daily schedule while satisfying all constraints, including cooling loading under the time-of-use (TOU rate. Based on the Radial Basis Function Network (RBFN and Ant Colony Optimization, an Ant-Based Radial Basis Function Network (ARBFN is constructed in the searching process. Simulation results indicate that reasonable solutions provide a practical and flexible framework allowing the economic dispatch of ice storage air-conditioning systems, and offering greater energy efficiency in dispatching chillers.

  16. OPTIMIZED FUEL INJECTOR DESIGN FOR MAXIMUM IN-FURNACE NOx REDUCTION AND MINIMUM UNBURNED CARBON

    Energy Technology Data Exchange (ETDEWEB)

    SAROFIM, A F; LISAUSKAS, R; RILEY, D; EDDINGS, E G; BROUWER, J; KLEWICKI, J P; DAVIS, K A; BOCKELIE, M J; HEAP, M P; PERSHING, D

    1998-01-01

    Reaction Engineering International (REI) has established a project team of experts to develop a technology for combustion systems which will minimize NO x emissions and minimize carbon in the fly ash. This much need technology will allow users to meet environmental compliance and produce a saleable by-product. This study is concerned with the NO x control technology of choice for pulverized coal fired boilers,"in-furnace NOx control," which includes: staged low-NOx burners, reburning, selective non-catalytic reduction (SNCR) and hybrid approaches (e.g., reburning with SNCR). The program has two primary objectives: 1) To improve the performance of "in-furnace" NOx control, processes. 2) To devise new, or improve existing, approaches for maximum "in-furnace" NOx control and minimum unburned carbon. The program involves: 1) fundamental studies at laboratory- and bench-scale to define NO reduction mechanisms in flames and reburning jets; 2) laboratory experiments and computer modeling to improve our two-phase mixing predictive capability; 3) evaluation of commercial low-NOx burner fuel injectors to develop improved designs, and 4) demonstration of coal injectors for reburning and low-NOx burners at commercial scale. The specific objectives of the two-phase program are to: 1 Conduct research to better understand the interaction of heterogeneous chemistry and two phase mixing on NO reduction processes in pulverized coal combustion. 2 Improve our ability to predict combusting coal jets by verifying two phase mixing models under conditions that simulate the near field of low-NOx burners. 3 Determine the limits on NO control by in-furnace NOx control technologies as a function of furnace design and coal type. 5 Develop and demonstrate improved coal injector designs for commercial low-NOx burners and coal reburning systems. 6 Modify the char burnout model in REI's coal

  17. Design and optimization of a noise reduction system for infrasonic measurements using elements with low acoustic impedance.

    Science.gov (United States)

    Alcoverro, Benoit; Le Pichon, Alexis

    2005-04-01

    The implementation of the infrasound network of the International Monitoring System (IMS) for the enforcement of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) increases the effort in the design of suitable noise reducer systems. In this paper we present a new design consisting of low impedance elements. The dimensioning and the optimization of this discrete mechanical system are based on numerical simulations, including a complete electroacoustical modeling and a realistic wind-noise model. The frequency response and the noise reduction obtained for a given wind speed are compared to statistical noise measurements in the [0.02-4] Hz frequency band. The effects of the constructive parameters-the length of the pipes, inner diameters, summing volume, and number of air inlets-are investigated through a parametric study. The studied system consists of 32 air inlets distributed along an overall diameter of 16 m. Its frequency response is flat up to 4 Hz. For a 2 m/s wind speed, the maximal noise reduction obtained is 15 dB between 0.5 and 4 Hz. At lower frequencies, the noise reduction is improved by the use of a system of larger diameter. The main drawback is the high-frequency limitation introduced by acoustical resonances inside the pipes.

  18. Model reduction for the dynamics and control of large structural systems via neutral network processing direct numerical optimization

    Science.gov (United States)

    Becus, Georges A.; Chan, Alistair K.

    1993-01-01

    Three neural network processing approaches in a direct numerical optimization model reduction scheme are proposed and investigated. Large structural systems, such as large space structures, offer new challenges to both structural dynamicists and control engineers. One such challenge is that of dimensionality. Indeed these distributed parameter systems can be modeled either by infinite dimensional mathematical models (typically partial differential equations) or by high dimensional discrete models (typically finite element models) often exhibiting thousands of vibrational modes usually closely spaced and with little, if any, damping. Clearly, some form of model reduction is in order, especially for the control engineer who can actively control but a few of the modes using system identification based on a limited number of sensors. Inasmuch as the amount of 'control spillover' (in which the control inputs excite the neglected dynamics) and/or 'observation spillover' (where neglected dynamics affect system identification) is to a large extent determined by the choice of particular reduced model (RM), the way in which this model reduction is carried out is often critical.

  19. Optimal dosing regimen of nitric oxide donor compounds for the reduction of Pseudomonas aeruginosa biofilm and isolates from wastewater membranes.

    Science.gov (United States)

    Barnes, Robert J; Bandi, Ratnaharika R; Wong, Wee Seng; Barraud, Nicolas; McDougald, Diane; Fane, Anthony; Kjelleberg, Staffan; Rice, Scott A

    2013-01-01

    Membrane fouling by bacterial biofilms remains a key challenge for membrane-based water purification systems. Here, the optimal biofilm dispersal potential of three nitric oxide (NO) donor compounds, viz. sodium nitroprusside, 6-(2-hydroxy-1-methyl-2-nitrosohydrazino)-N-methyl-1-hexanamine (MAHMA NONOate) and 1-(hydroxy-NNO-azoxy)-L-proline, disodium salt, was investigated using Pseudomonas aeruginosa PAO1 as a model organism. Dispersal was quantitatively assessed by confocal microscopy [bacterial cells and the components of the extracellular polymeric substances (EPS) (polysaccharides and extracellular DNA)] and colony-forming unit counts. The three NO donor compounds had different optimal exposure times and concentrations, with MAHMA NONOate being the optimal NO donor compound. Biofilm dispersal correlated with a reduction in both bacterial cells and EPS. MAHMA NONOate also reduced single species biofilms formed by bacteria isolated from industrial membrane bioreactor and reverse osmosis membranes, as well as in isolates combined to generate mixed species biofilms. The data present strong evidence for the application of these NO donor compounds for prevention of biofouling in an industrial setting.

  20. Improving Intercomparability of Marine Biogeochemical Time Series

    Science.gov (United States)

    Benway, Heather M.; Telszewski, Maciej; Lorenzoni, Laura

    2013-04-01

    Shipboard biogeochemical time series represent one of the most valuable tools scientists have to quantify marine elemental fluxes and associated biogeochemical processes and to understand their links to changing climate. They provide the long, temporally resolved data sets needed to characterize ocean climate, biogeochemistry, and ecosystem variability and change. However, to monitor and differentiate natural cycles and human-driven changes in the global oceans, time series methodologies must be transparent and intercomparable when possible. To review current shipboard biogeochemical time series sampling and analytical methods, the International Ocean Carbon Coordination Project (IOCCP; http://www.ioccp.org/) and the Ocean Carbon and Biogeochemistry Program (http://www.us-ocb.org/) convened an international ocean time series workshop at the Bermuda Institute for Ocean Sciences.

  1. Optimizing Power Heterogeneous Functional Units for Dynamic and Static Power Reduction

    Directory of Open Access Journals (Sweden)

    Toshinori Sato

    2014-12-01

    Full Text Available Power consumption is the major constraint for modern microprocessor designs. In particular, static power consumption becomes a serious problem as the transistor size shrinks via semiconductor technology improvement. This paper proposes a technique that reduces the static power consumed by functional units. It exploits the activity rate of functional units and utilizes the power heterogeneous functional units. From detailed simulations, we investigate the conditions in which the proposed technique works effectively for simultaneous dynamic and static power reduction and find that we can reduce the total power by 11.2% if two out of four leaky functional units are replaced by leakless ones in the situation where the static power occupies half of the total power.

  2. Reduction of fine particle emissions from wood combustion with optimized condensing heat exchangers.

    Science.gov (United States)

    Gröhn, Arto; Suonmaa, Valtteri; Auvinen, Ari; Lehtinen, Kari E J; Jokiniemi, Jorma

    2009-08-15

    In this study, we designed and built a condensing heat exchanger capable of simultaneous fine particle emission reduction and waste heat recovery. The deposition mechanisms inside the heat exchanger prototype were maximized using a computer model which was later compared to actual measurements. The main deposition mechanisms were diffusio- and thermophoresis which have previously been examined in similar conditions only separately. The obtained removal efficiency in the experiments was measured in the total number concentration and ranged between 26 and 40% for the given pellet stove and the heat exchanger. Size distributions and number concentrations were measured with a TSI Fast mobility particle sizer (FMPS). The computer model predicts that there exists a specific upper limit for thermo- and diffusiophoretic deposition for each temperature and water vapor concentration in the flue gas.

  3. A NOTE ON LOGARITHMIC SMOOTHING IN SEMI-INFINITE OPTIMIZATION UNDER REDUCTION APPROACH*

    Directory of Open Access Journals (Sweden)

    Francisco Guerra-Vazquez

    2013-02-01

    Full Text Available This note deals with a semi-infinite optimization problem which is defined by infinitely many inequality constraints. By applying a logarithmic barrier function, a family of interior point approximations of the feasible set is obtained where locally the original feasible set and its approximations are homeomorphic. Under generic assumptions on the structure of the original feasible set, strongly stable stationary points of the original problem are considered and it is shown that there is a one-to-one correspondence between the stationary points (and their stationary indices of the original problem and those of its approximations. Corresponding convergence results, global aspects and a relationship to a standard interior-point approach are discussed.

  4. Optimal control based on adaptive model reduction approach to control transfer phenomena

    Science.gov (United States)

    Oulghelou, Mourad; Allery, Cyrille

    2017-01-01

    The purpose of optimal control is to act on a set of parameters characterizing a dynamical system to achieve a target dynamics. In order to reduce CPU time and memory storage needed to perform control on evolution systems, it is possible to use reduced order models (ROMs). The mostly used one is the Proper Orthogonal Decomposition (POD). However the bases constructed in this way are sensitive to the configuration of the dynamical system. Consequently, the need of full simulations to build a basis for each configuration is time consuming and makes that approach still relatively expensive. In this paper, to overcome this difficulty we suggest to use an adequate bases interpolation method. It consists in computing the associated bases to a distribution of control parameters. These bases are afterwards called in the control algorithm to build a reduced basis adapted to a given control parameter. This interpolation method involves results of the calculus of Geodesics on Grassmann manifold.

  5. Vibration Reduction of Open-chain Flexible Manipulators by Optimizing Independent Motions of Branch Links

    Institute of Scientific and Technical Information of China (English)

    Bian Yushu; Gao Zhihui; Yun Chao

    2008-01-01

    In order to suppress vibration in flexible manipulators, a new type of manipulator mechanism with controllable local degrees of freedom is proposed. This mechanism consists of a main chain and some branch links. The main chain is of a flexible open-chain configuration with an end-effector installed at its tip, and the rigid branch links are able to perform active movements. It is proved by kinematics and dynamic analysis that, the branch links bear no direct kinematic relation to the main chain, but their independent motions can strongly affect the dynamic behavior and performance of the flexible manipulator. Then comes a new idea of suppressing vibration, in which independent motions of the branch links are used to suppress the undesired vibration of the flexible main chain through dynamic coupling. On this basis, an optimal method for reducing vibration of flexible manipulators is proposed. Finally, the effectiveness of this method is verified by numerical simulations.

  6. Design, modeling, and optimization of compliant tensegrity fabrics for the reduction of turbulent skin friction

    Science.gov (United States)

    Luo, Haoxiang; Bewley, Thomas R.

    2003-07-01

    In this project, we have designed a new type of flexible surface, which we call a tensegrity fabric, and simulated the interaction of this flexible surface with a near-wall turbulent flow. The fabric is constructed by weaving together both members in tension (tendons) and members in compression (bars) to form a plate-class tensegrity structure, then covering this discrete flexible structure with a continuous flexible membrane. We have modeled the flow/structure interaction by coupling a spectral Direct Numerical Simulation (DNS) code resolving the (continuous) turbulent flow system and an efficient structural dynamics code which simulates direclty the motion of the (discrete) extensive, small-scale, and interconnected tensegrity structure. The structural dynamics code used was developed by Prof. Robert Skelton's lab at UC San Diego. An immersed boundary method is used to capture the effect of the moving boundary in the DNS, and a simple tessellation strategy is used to lump the distributed fluid forces (skin friction and pressure) acting on the membrane onto the nearby nodes of the tensegrity structure. Our ultimate goal is to use this new simulation tool to optimize the design of the tensegrity structure (specifically, the orientation, stiffness, mass, and damping of each of the individual tendons and bars in the unit cell upon which the tensegrity structure is based). Our objective in this optimization is to tune the compliance properties of the fabric in such a way as to reduce the skin-friction drag induced at teh flow/structure interface by weakening the vortices near the wall in the overlying turbulent flow.

  7. Biogeochemical Coupling between Ocean and Sea Ice

    Science.gov (United States)

    Wang, S.; Jeffery, N.; Maltrud, M. E.; Elliott, S.; Wolfe, J.

    2016-12-01

    Biogeochemical processes in ocean and sea ice are tightly coupled at high latitudes. Ongoing changes in Arctic and Antarctic sea ice domain likely influence the coupled system, not only through physical fields but also biogeochemical properties. Investigating the system and its changes requires representation of ocean and sea ice biogeochemical cycles, as well as their coupling in Earth System Models. Our work is based on ACME-HiLAT, a new offshoot of the Community Earth System Model (CESM), including a comprehensive representation of marine ecosystems in the form of the Biogeochemical Elemental Cycling Module (BEC). A full vertical column sea ice biogeochemical module has recently been incorporated into the sea ice component. We have further introduced code modifications to couple key growth-limiting nutrients (N, Si, Fe), dissolved and particulate organic matter, and phytoplankton classes that are important in polar regions between ocean and sea ice. The coupling of ocean and sea ice biology-chemistry will enable representation of key processes such as the release of important climate active constituents or seeding algae from melting sea ice into surface waters. Sensitivity tests suggest sea ice and ocean biogeochemical coupling influences phytoplankton competition, biological production, and the CO2 flux. Sea ice algal seeding plays an important role in determining phytoplankton composition of Arctic early spring blooms, since different groups show various responses to the seeding biomass. Iron coupling leads to increased phytoplankton biomass in the Southern Ocean, which also affects carbon uptake via the biological pump. The coupling of macronutrients and organic matter may have weaker influences on the marine ecosystem. Our developments will allow climate scientists to investigate the fully coupled responses of the sea ice-ocean BGC system to physical changes in polar climate.

  8. Electric shortcuts of biogeochemical processes

    Science.gov (United States)

    Nielsen, Lars Peter; Risgaard-Petersen, Nils; Fossing, Henrik; Christensen, Peter Bondo; Sayama, Mikio

    2010-05-01

    Recent observations in marine sediment have revealed conductive networks transmitting electrons from oxidation processes in the anoxic zone to oxygen reduction in the oxic zone. The involved electrochemical processes seem to be biologically catalyzed and may account for more than half of the oxygen uptake in laboratory incubations of initially homogenized and stabilized sediment. Using microsensors and process rate measurements we further investigated the effect of the electric currents on sediment biogeochemistry. Dissolved sulfide readily donated electrons to the networks and could be depleted below detection limit in a several cm thick layer below the oxic zone. Subsequent dissolution of iron sulphide was indicated by mobilization of ferrous iron being precipitated again as ferric iron at the oxic-anoxic interface. Lowered sulphate reduction rates in the upper centimeters of the sediment confirmed the depth range of the electric communication and indicated donation of electrons directly from organotrophic bacteria. The separation of oxidation and reduction processes created steep pH gradients eventually causing carbonate precipitation at the surface and probably also carbonate dissolution at depth. We suggest that the electric currents allowing reactions between compounds far from one another have significant effects in natural marine sediments as well as other environments with redox gradients.

  9. Energy in the Netherlands. Optimized pathways to CO2 reduction in the Dutch context

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-09-15

    This document reports the findings of research undertaken by the Energy Forum NL (EFNL) which consists of companies active in different parts of the energy sector. The group strives for a more long-term, stable energy policy and investment climate in the Netherlands, one that will help realize overall climate ambitions. This report is part of the group's contribution to the energy debate in the Netherlands; it lays out a fact-based, objective analysis of the potential energy mix if one assumes a continued focus on carbon abatement. In this report, the Energy Forum NL provides pathways that show how the Netherlands can best contribute to the EU target of 80% CO2e emission reduction by 2050 compared to 1990. They particularly focus on the goal for the next 20 years: reducing CO2e emissions by 40% by 2030 compared to 1990. The Forum selected 40% as a midway target for 80% in 2050; this falls within the EU ambition of 40%-44% in 2030.1 The period beyond 2030, which is much more uncertain, is modeled in less detail. However, the Forum took care to not let the choice of any pathway during 2010-2030 lock a pathway after 2030 in or out. A 'least cost' approach, which works across sectors, is used to reduce emissions. In a 'least cost' approach, all emission reduction measures are ranked on costs and implemented progressively (starting from the cheapest) until the targeted abatement level is reached. In addition, a few developing technologies are implemented even if they are more expensive than alternatives. This choice prevents technology lock-in, ensures a more versatile, resilient energy system and provides a reasonable starting position for the period post-2030. The report assumes a pan-European approach for the power sector, which is the key sector in the Emissions Trading Scheme (ETS); in this case, Dutch abatement options 'compete' with those in other EU countries. For the other sectors it uses a national approach. Non-cost factors

  10. Optimization of internals for Selective Catalytic Reduction (SCR) for NO removal.

    Science.gov (United States)

    Lei, Zhigang; Wen, Cuiping; Chen, Biaohua

    2011-04-15

    This work tried to identify the relationship between the internals of selective catalytic reduction (SCR) system and mixing performance for controlling ammonia (NH(3)) slip. In the SCR flow section, arranging the flow-guided internals can improve the uniformity of velocity distribution but is unfavorable for the uniformity of NH(3) concentration distribution. The ammonia injection grids (AIG) with four kinds of nozzle diameters (i.e., 1.0 mm, 1.5 mm, 2.0 mm, and mixed diameters) were investigated, and it was found that the AIG with mixed nozzle diameters in which A3, A4, B3, and B4 nozzles' diameters are 1.0 mm and other nozzles' diameters are 1.5 mm is the most favorable for the uniformity of NH(3) concentration distribution. In the SCR reactor section, the appropriate space length between two catalyst layers, which serves as gas mixing in order to prevent maldistribution of gas concentrations into the second catalyst layer, under the investigated conditions is about 100, 1000, and 12 mm for honeycomb-like cordierite catalyst, plate-type catalysts with parallel channel arrangement, and with cross channel arrangement, respectively. Therefore, the cross channel arrangement is superior to the parallel channel arrangement in saving the SCR reactor volume.

  11. Study of UPFC Optimal Location Considering Loss Reduction and Improvement of Voltage Stability and Power Flow

    Directory of Open Access Journals (Sweden)

    Islam Youcef DJILANI KOBIBI

    2014-02-01

    Full Text Available With the increase in power demand, operation and planning of large interconnected power system are becoming more complex, so power system will become less secure and stable. A new concept of Flexible AC Transmission system (FACTS brought radical changes in the power system operation and control. FACTS controllers narrow the gap between the no controlled and the controlled power system mode of operation, by providing additional degrees of freedom to control power flows and voltages. Unified Power Flow Controller (UPFC is a versatile FACTS device which can independently or simultaneously control the active power, the reactive power, and the bus voltage to which it is connected. The main purpose of this paper is to identify the optimal location of the Unified Power Flow Controller (UPFC in order to minimize active power losses and improve the voltage profiles using the injection model of the (UPFC in Newton-Raphson load flow algorithm, in an IEEE- 14, 30, 57, 118, 300 Bus test systems.

  12. Biogeochemical aspects of aquifer thermal energy storage.

    NARCIS (Netherlands)

    Brons, H.J.

    1992-01-01

    During the process of aquifer thermal energy storage the in situ temperature of the groundwater- sediment system may fluctuate significantly. As a result the groundwater characteristics can be considerably affected by a variety of chemical, biogeochemical and microbiological reactions. The inter

  13. Biogeochemical speciation of Fe in ocean water

    NARCIS (Netherlands)

    Hiemstra, T.; Riemsdijk, van W.H.

    2006-01-01

    The biogeochemical speciation of Fe in seawater has been evaluated using the consistent Non-Ideal Competitive Adsorption model (NICA¿Donnan model). Two types of data sets were used, i.e. Fe-hydroxide solubility data and competitive ligand equilibration/cathodic stripping voltammetry (CLE/CSV) Fe

  14. Biogeochemical gradients above a coal tar DNAPL

    Energy Technology Data Exchange (ETDEWEB)

    Scherr, Kerstin E., E-mail: kerstin.brandstaetter-scherr@boku.ac.at [University of Natural Resources and Life Sciences Vienna (BOKU), Department IFA-Tulln, Institute for Environmental Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln (Austria); Backes, Diana [University of Natural Resources and Life Sciences Vienna (BOKU), Department IFA-Tulln, Institute for Environmental Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln (Austria); Scarlett, Alan G. [University of Plymouth, Petroleum and Environmental Geochemistry Group, Biogeochemistry Research Centre, Drake Circus, Plymouth, Devon PL4 8AA (United Kingdom); Lantschbauer, Wolfgang [Government of Upper Austria, Directorate for Environment and Water Management, Division for Environmental Protection, Kärntner Strasse 10-12, 4021 Linz (Austria); Nahold, Manfred [GUT Gruppe Umwelt und Technik GmbH, Ingenieurbüro für Technischen Umweltschutz, Plesching 15, 4040 Linz (Austria)

    2016-09-01

    Naturally occurring distribution and attenuation processes can keep hydrocarbon emissions from dense non aqueous phase liquids (DNAPL) into the adjacent groundwater at a minimum. In a historically coal tar DNAPL-impacted site, the de facto absence of a plume sparked investigations regarding the character of natural attenuation and DNAPL resolubilization processes at the site. Steep vertical gradients of polycyclic aromatic hydrocarbons, microbial community composition, secondary water quality and redox-parameters were found to occur between the DNAPL-proximal and shallow waters. While methanogenic and mixed-electron acceptor conditions prevailed close to the DNAPL, aerobic conditions and very low dissolved contaminant concentrations were identified in three meters vertical distance from the phase. Comprehensive two-dimensional gas chromatography–mass spectrometry (GC × GC–MS) proved to be an efficient tool to characterize the behavior of the present complex contaminant mixture. Medium to low bioavailability of ferric iron and manganese oxides of aquifer samples was detected via incubation with Shewanella alga and evidence for iron and manganese reduction was collected. In contrast, 16S rDNA phylogenetic analysis revealed the absence of common iron reducing bacteria. Aerobic hydrocarbon degraders were abundant in shallow horizons, while nitrate reducers were dominating in deeper aquifer regions, in addition to a low relative abundance of methanogenic archaea. Partial Least Squares – Canonical Correspondence Analysis (PLS-CCA) suggested that nitrate and oxygen concentrations had the greatest impact on aquifer community structure in on- and offsite wells, which had a similarly high biodiversity (H’ and Chao1). Overall, slow hydrocarbon dissolution from the DNAPL appears to dominate natural attenuation processes. This site may serve as a model for developing legal and technical strategies for the treatment of DNAPL-impacted sites where contaminant plumes are

  15. Reduction of Large-scale Turbulence and Optimization of Flows in the Madison Dynamo Experiment

    Science.gov (United States)

    Taylor, N. Z.

    2011-10-01

    The Madison Dynamo Experiment seeks to observe a magnetic field grow at the expense of kinetic energy in a flow of liquid sodium. The enormous Reynolds numbers of the experiment and its two vortex geometry creates strong turbulence, which in turn leads to transport of magnetic flux consistent with an increase of the effective resistivity. The increased effective resistivity implies that faster flows are required for the dynamo to operate. Three major results from the experiment will be reported in this talk. 1) A new probe technique has been developed for measuring both the fluctuating velocity and magnetic fields which has allowed a direct measurement of the turbulent EMF from . 2) The scale of the largest eddies in the experiment has been reduced by an equatorial baffle on the vessel boundary. This modification of the flow at the boundary results in strong field generation and amplification by the mean velocity of the flow, and the role of turbulence in generating currents is reduced. The motor power required to drive a given flow speed is reduced by 20%, the effective Rm, as measured by the toroidal windup of the field(omega effect), increased by a factor of ~2.4, and the turbulent EMF (previously measured to be as large as the induction by the mean flow) is eliminated. These results all indicate that the equatorial baffle has eliminated the largest-scale eddies in the flow. 3) Flow optimization is now possible by adjusting the pitch of vanes installed on the vessel wall. An analysis of the kinematic prediction for dynamo excitation reveals that the threshold for excitation is quite sensitive to the helical pitch of the flow. Computational fluid dynamics simulations of the flow showed that by adjusting the angle of the vanes on the vessel wall (which control the helical pitch of the flow) we should be able to minimize the critical velocity at which the dynamo onset occurs. Experiments are now underway to exploit this new capability in tailoring the large

  16. Optimization of Ru{sub x}Se{sub y} electrocatalyst loading for oxygen reduction in a PEMFC

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Huerta, R.G. [Instituto Politecnico Nacional, Laboratorio de Electroquimica y Corrosion ESIQIE, UPALP, 07738 Mexico, D.F., Mexico (Mexico); Guzman-Guzman, A.; Solorza-Feria, O. [Depto. Quimica, Centro de Investigacion y de Estudios Avanzados del IPN, A. Postal 14-740, 07360 Mexico D.F., Mexico (Mexico)

    2010-11-15

    The synthesis, characterization and optimization of Ru{sub x}Se{sub y} catalyst loading as a cathode electrode for a single polymer electrolyte membrane fuel cell, PEMFC were investigated. Ru{sub x}Se{sub y} catalyst was synthesized via a decarbonylation of Ru{sub 3}(CO){sub 12} and elemental selenium in 1,6-hexanediol under refluxing conditions for 2 h. The powder electrocatalyst was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and examined for the oxygen reduction reaction (ORR) in 0.5M H{sub 2}SO{sub 4} by rotating disk electrode (RDE) and in membrane-electrode assemblies, MEAs for a single PEMFC. Results indicate the formation of agglomerates of crystalline particles with nanometric size embedded in an amorphous phase. The catalyst exhibited high current density and lower overpotential for the ORR compared to that of Ru{sub x} cluster catalyst. Dispersed Ru{sub x}Se{sub y} catalyst loading on Vulcan carbon was optimized as a cathode electrode by performance testing in a single H{sub 2}-O{sub 2} fuel cell. (author)

  17. Geometric optimization of a step bearing for a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.

    Science.gov (United States)

    Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi

    2013-09-01

    A hydrodynamically levitated centrifugal blood pump with a semi-open impeller has been developed for mechanical circulatory assistance. However, a narrow bearing gap has the potential to cause hemolysis. The purpose of the present study is to optimize the geometric configuration of the hydrodynamic step bearing in order to reduce hemolysis by expansion of the bearing gap. First, a numerical analysis of the step bearing, based on lubrication theory, was performed to determine the optimal design. Second, in order to assess the accuracy of the numerical analysis, the hydrodynamic forces calculated in the numerical analysis were compared with those obtained in an actual measurement test using impellers having step lengths of 0%, 33%, and 67% of the vane length. Finally, a bearing gap measurement test and a hemolysis test were performed. As a result, the numerical analysis revealed that the hydrodynamic force was the largest when the step length was approximately 70%. The hydrodynamic force calculated in the numerical analysis was approximately equivalent to that obtained in the measurement test. In the measurement test and the hemolysis test, the blood pump having a step length of 67% achieved the maximum bearing gap and reduced hemolysis, as compared with the pumps having step lengths of 0% and 33%. It was confirmed that the numerical analysis of the step bearing was effective, and the developed blood pump having a step length of approximately 70% was found to be a suitable configuration for the reduction of hemolysis.

  18. Optimization of Flotation Process for Reduction of Alumina and Silica from Screw Classifier Overflow of an Iron Ore Washing Plant

    Directory of Open Access Journals (Sweden)

    T V Vijaya Kumar

    2014-03-01

    Full Text Available Reverse flotation process was optimized by an experimental programme based on statistical analysis for reduction of silica and alumina levels from screw classifier overflow so as to enrich iron values. Flotation of alumina and silica bearing minerals with Sokem 521C and starch as collector and depressant respectively was studied to estimate their optimum levels at different particle sizes. A two-level three factor design of experiments showed that particle size is insignificant in the ranges of study. Tests on an orthogonal design of the hexagonal type were then carried out to determine the effects of the other two variables, on the response, Selectivity Index (SI, a measure of separation efficiency of iron values from alumina and silica. Regression equations were developed as models and response contours were plotted. Maximum response (SI of 2.25 has been optimized at 0.306 kg/t of amine collector, 1.0043 kg/t of starch at a particle size of 40 µm.

  19. Diffusion tensor tractography of the brainstem pyramidal tract; A study on the optimal reduction factor in parallel imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Yun Jung; Park, Jong Bin; Kim, Jae Hyoung; Choi, Byung Se; Jung, Cheol Kyu [Dept. of of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of)

    2016-08-15

    Parallel imaging mitigates susceptibility artifacts that can adversely affect diffusion tensor tractography (DTT) of the pons depending on the reduction (R) factor. We aimed to find the optimal R factor for DTT of the pons that would allow us to visualize the largest possible number of pyramidal tract fibers. Diffusion tensor imaging was performed on 10 healthy subjects at 3 Tesla based on single-shot echo-planar imaging using the following parameters: b value, 1000 s/mm{sup 2}; gradient direction, 15; voxel size, 2 × 2 × 2 mm{sup 3}; and R factors, 1, 2, 3, 4, and 5. DTT of the right and left pyramidal tracts in the pons was conducted in all subjects. Signal-to-noise ratio (SNR), image distortion, and the number of fibers in the tracts were compared across R factors. SNR, image distortion, and fiber number were significantly different according to R factor. Maximal SNR was achieved with an R factor of 2. Image distortion was minimal with an R factor of 5. The number of visible fibers was greatest with an R factor of 3. R factor 3 is optimal for DTT of the pontine pyramidal tract. A balanced consideration of SNR and image distortion, which do not have the same dependence on the R factor, is necessary for DTT of the pons.

  20. Mechanism and optimization of titanium carbide-reinforced iron composite formation through carbothermal reduction of hematite and anatase

    Energy Technology Data Exchange (ETDEWEB)

    Hasniyati, Md Razi; Zuhailawati, Hussain, E-mail: zuhaila@eng.usm.my; Ramakrishnan, Sivakumar; Hamid, Sheikh Abdul Rezan Sheikh Abdul

    2014-02-25

    Highlights: • Reduction mechanism of Fe{sub 2}O{sub 3} and TiO{sub 2} mixture in formation Fe–TiC composite was discovered. • Factorial design is used to define interaction between calcination temperature and FeCl{sub 3} content. • Increasing FeCl{sub 3} content and calcination temperature increased the formation of Fe and TiC phases. • Microhardness and density of the sintered composite improved noticeably. -- Abstract: This study investigated an optimization of titanium carbide-reinforced iron composite fabricated using a combination of powder metallurgy and carbothermal reduction of hematite-anatase mixture using 2{sup k} factorial design. The composite formation mechanism is described as well. Powders of hematite, anatase and graphite with mole ratio of 1:1:6 were mixed for 1 h together with 0 wt%, 1 wt% and 5 wt% FeCl{sub 3}. The mixture was pressed at 5 MPa, calcined for 1 h at 1000 °C, 1100 °C or 1200 °C and sintered at 1200 °C. X-ray diffraction of the calcined powder showed that with increasing temperature TiO{sub 2} was reduced to TiC through formation of various suboxides (Ti{sub 3}O{sub 5} and Ti{sub 2}O{sub 3}). Scanning electron microscope observation of the sintered composite indicated that addition of FeCl{sub 3} enhanced the formation of TiC in iron matrix. Consequently, microhardness and density of the sintered composite improved noticeably. Based on microhardness, green density and sintered density measurements, design of experiment analysis suggested that an increase in both FeCl{sub 3} content and calcination temperature increased the percentage of hematite and anatase reduction.

  1. Response Surface Optimization for Process Parameters of LiFePO_4/C Preparation by Carbothermal Reduction Technology

    Institute of Scientific and Technical Information of China (English)

    杨克迪; 谭芳香; 王凡; 龙云飞; 文衍宣

    2012-01-01

    A statistically based optimization strategy is used to optimize the carbothermal reduction technology for the synthesis of LiFePO4/C using LiOH,FePO4 and sucrose as raw materials.The experimental data for fitting the response are collected by the central composite rotatable design(CCD).A second order model for the discharge ca-pacity of LiFePO4/C is expressed as a function of sintering temperature,sintering time and carbon content.The ef-fects of individual variables and their interactions are studied by a statistical analysis(ANOVA).The results show that the linear effects and the quadratic effects of sintering temperature,carbon content and the interactions among these variables are statistically significant,while those effects of sintering time are insignificant.Response surface plots for spatial representation of the model illustrate that the discharge capacity depends on sintering temperature and carbon content more than sintering time.The model obtained gives the optimized reaction parameters of sinter-ing temperature at 652.0 ℃,carbon content of 34.33 g?mol-1 and 8.48 h sintering time,corresponding to a dis-charge capacity of 150.8 mA·h·g-1.The confirmatory test with these optimum parameters gives the discharge ca-pacity of 147.2 and 105.1 mA·h·g-1 at 0.5 and 5 C,respectively.

  2. Reversible redox chemistry of quinones: impact on biogeochemical cycles.

    Science.gov (United States)

    Uchimiya, Minori; Stone, Alan T

    2009-10-01

    The role of quinone biomolecules and quinone moieties of natural organic matter (NOM) as the electron transfer mediator in essential biogeochemical processes such as iron bioreduction and contaminant degradation has received considerable interests in the past decade. Hypothesized electron shuttling mechanism must be evaluated based on the availability and stability of quinones under a given environmental setting. The goal of this review is to examine the source, reactivity, and fate of potential quinone catalysts with respect to chemical interactions (e.g., with other quinones and nucleophiles) that will inevitably occur in complex environmental media. We will first discuss natural and anthropogenic sources of quinones in aqueous environments, and fundamental transformation pathways including cross reaction, autoxidation, and addition reactions. We will then assess how the described sources (molecular structure) and transformation pathways (stability) will impact the ability of a quinone molecule to catalyze a biogeochemical process. Thermodynamics and kinetics of electron transfer reactions with both the electron donor (e.g., hydrogen sulfide as a bulk reductant) and the terminal electron acceptor (e.g., nitroaromatic explosives in contaminant degradation), and stability towards irreversible side reactions are the key factors determining the geochemical conditions under which the catalysis by a quinone molecule will be operative.

  3. Biogeochemical redox processes and their impact on contaminant dynamics

    Science.gov (United States)

    Borch, Thomas; Kretzschmar, Ruben; Kappler, Andreas; Van Cappellen, Philippe; Ginder-Vogel, Matthew; Campbell, Kate M.

    2010-01-01

    Life and element cycling on Earth is directly related to electron transfer (or redox) reactions. An understanding of biogeochemical redox processes is crucial for predicting and protecting environmental health and can provide new opportunities for engineered remediation strategies. Energy can be released and stored by means of redox reactions via the oxidation of labile organic carbon or inorganic compounds (electron donors) by microorganisms coupled to the reduction of electron acceptors including humic substances, iron-bearing minerals, transition metals, metalloids, and actinides. Environmental redox processes play key roles in the formation and dissolution of mineral phases. Redox cycling of naturally occurring trace elements and their host minerals often controls the release or sequestration of inorganic contaminants. Redox processes control the chemical speciation, bioavailability, toxicity, and mobility of many major and trace elements including Fe, Mn, C, P, N, S, Cr, Cu, Co, As, Sb, Se, Hg, Tc, and U. Redox-active humic substances and mineral surfaces can catalyze the redox transformation and degradation of organic contaminants. In this review article, we highlight recent advances in our understanding of biogeochemical redox processes and their impact on contaminant fate and transport, including future research needs.

  4. Breaking Computational Barriers: Real-time Analysis and Optimization with Large-scale Nonlinear Models via Model Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Carlberg, Kevin Thomas [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Quantitative Modeling and Analysis; Drohmann, Martin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Quantitative Modeling and Analysis; Tuminaro, Raymond S. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Computational Mathematics; Boggs, Paul T. [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Quantitative Modeling and Analysis; Ray, Jaideep [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Quantitative Modeling and Analysis; van Bloemen Waanders, Bart Gustaaf [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Optimization and Uncertainty Estimation

    2014-10-01

    -model errors. This enables ROMs to be rigorously incorporated in uncertainty-quantification settings, as the error model can be treated as a source of epistemic uncertainty. This work was completed as part of a Truman Fellowship appointment. We note that much additional work was performed as part of the Fellowship. One salient project is the development of the Trilinos-based model-reduction software module Razor , which is currently bundled with the Albany PDE code and currently allows nonlinear reduced-order models to be constructed for any application supported in Albany. Other important projects include the following: 1. ROMES-equipped ROMs for Bayesian inference: K. Carlberg, M. Drohmann, F. Lu (Lawrence Berkeley National Laboratory), M. Morzfeld (Lawrence Berkeley National Laboratory). 2. ROM-enabled Krylov-subspace recycling: K. Carlberg, V. Forstall (University of Maryland), P. Tsuji, R. Tuminaro. 3. A pseudo balanced POD method using only dual snapshots: K. Carlberg, M. Sarovar. 4. An analysis of discrete v. continuous optimality in nonlinear model reduction: K. Carlberg, M. Barone, H. Antil (George Mason University). Journal articles for these projects are in progress at the time of this writing.

  5. Certain investigations on the reduction of side lobe level of an uniform linear antenna array using biogeography based optimization technique with sinusoidal migration model and simplified-BBO

    Indian Academy of Sciences (India)

    T S Jeyali Laseetha; R Sukanesh

    2014-02-01

    In this paper, we propose biogeography based optimization technique, with linear and sinusoidal migration models and simplified biogeography based optimization (S-BBO), for uniformly spaced linear antenna array synthesis to maximize the reduction of side lobe level (SLL). This paper explores biogeography theory. It generalizes two migration models in BBO namely, linear migration model and sinusoidal migration model. The performance of SLL reduction in ULA is investigated. Our performance study shows that among the two, sinusoidal migration model is a promising candidate for optimization. In our work, simplified – BBO algorithmis also deployed. This determines an optimum set value for amplitude excitations of antenna array elements that generate a radiation pattern with maximum side lobe level reduction. Our detailed investigation also shows that sinusoidal migration model of BBO performs better compared to the other evolutionary algorithms discussed in this paper.

  6. Phototrophic bacteria and their role in the biogeochemical sulfur cycle

    Science.gov (United States)

    Trueper, H. G.

    1985-01-01

    An essential step that cannot be bypassed in the biogeochemical cycle of sulfur today is dissimilatory sulfate reduction by anaerobic bacteria. The enormous amounts of sulfides produced by these are oxidized again either anaerobically by phototrophic bacteria or aerobically by thiobacilli and large chemotrophic bacteria (Beggiatoa, Thiovulum, etc.). Phototrophic bacteria use sulfide, sulfur, thiosulfate, and sulfite as electron donors for photosynthesis. The most obvious intermediate in their oxidative sulfur metabolism is a long chain polysulfide that appears as so called sulfur globules either inside (Chromatiaceae) or outside (Ectothiorhodospiraceae, Chlorobiaceae, and some of the Rhodospirillaceae) the cells. The assimilation of sulfur compounds in phototrophic bacteria is in principle identical with that of nonphototrophic bacteria. However, the Chlorobiaceae and some of the Chromatiaceae and Rhodospirillaceae, unable to reduce sulfate, rely upon reduced sulfur for biosynthetic purposes.

  7. Electric currents couple spatially separated biogeochemical processes in marine sediment

    DEFF Research Database (Denmark)

    Nielsen, Lars Peter; Risgaard-Petersen, Nils; Fossing, Henrik

    2010-01-01

    Some bacteria are capable of extracellular electron transfer, thereby enabling them to use electron acceptors and donors without direct cell contact 1, 2, 3, 4 . Beyond the micrometre scale, however, no firm evidence has previously existed that spatially segregated biogeochemical processes can...... be coupled by electric currents in nature. Here we provide evidence that electric currents running through defaunated sediment couple oxygen consumption at the sediment surface to oxidation of hydrogen sulphide and organic carbon deep within the sediment. Altering the oxygen concentration in the sea water...... in the sediment was driven by electrons conducted from the anoxic zone. A distinct pH peak in the oxic zone could be explained by electrochemical oxygen reduction, but not by any conventional sets of aerobic sediment processes. We suggest that the electric current was conducted by bacterial nanowires combined...

  8. Optimal bearing gap of a multiarc radial bearing in a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis.

    Science.gov (United States)

    Kosaka, Ryo; Yasui, Kazuya; Nishida, Masahiro; Kawaguchi, Yasuo; Maruyama, Osamu; Yamane, Takashi

    2014-09-01

    We have developed a hydrodynamically levitated centrifugal pump as a bridge-to-decision device. The purpose of the present study is to determine the optimal bearing gap of a multiarc radial bearing in the developed blood pump for the reduction of hemolysis. We prepared eight pump models having bearing gaps of 20, 30, 40, 80, 90, 100, 180, and 250 μm. The driving conditions were set to a pressure head of 200 mm Hg and a flow rate of 4 L/min. First, the orbital radius of the impeller was measured for the evaluation of the impeller stability. Second, the hemolytic property was evaluated in an in vitro hemolysis test. As a result, the orbital radius was not greater than 15 μm when the bearing gap was between 20 and 100 μm. The relative normalized index of hemolysis (NIH) ratios in comparison with BPX-80 were 37.67 (gap: 20 μm), 0.95 (gap: 30 μm), 0.96 (gap: 40 μm), 0.82 (gap: 80 μm), 0.77 (gap: 90 μm), 0.92 (gap: 100 μm), 2.76 (gap: 180 μm), and 2.78 (gap: 250 μm). The hemolysis tended to increase at bearing gaps of greater than 100 μm due to impeller instability. When the bearing gap decreased from 30 to 20 μm, the relative NIH ratios increased significantly from 0.95 to 37.67 times (P pump for the reduction of hemolysis.

  9. Dimension reduction: additional benefit of an optimal filter for independent component analysis to extract event-related potentials.

    Science.gov (United States)

    Cong, Fengyu; Leppänen, Paavo H T; Astikainen, Piia; Hämäläinen, Jarmo; Hietanen, Jari K; Ristaniemi, Tapani

    2011-09-30

    The present study addresses benefits of a linear optimal filter (OF) for independent component analysis (ICA) in extracting brain event-related potentials (ERPs). A filter such as the digital filter is usually considered as a denoising tool. Actually, in filtering ERP recordings by an OF, the ERP' topography should not be changed by the filter, and the output should also be able to be modeled by the linear transformation. Moreover, an OF designed for a specific ERP source or component may remove noise, as well as reduce the overlap of sources and even reject some non-targeted sources in the ERP recordings. The OF can thus accomplish both the denoising and dimension reduction (reducing the number of sources) simultaneously. We demonstrated these effects using two datasets, one containing visual and the other auditory ERPs. The results showed that the method including OF and ICA extracted much more reliable components than the sole ICA without OF did, and that OF removed some non-targeted sources and made the underdetermined model of EEG recordings approach to the determined one. Thus, we suggest designing an OF based on the properties of an ERP to filter recordings before using ICA decomposition to extract the targeted ERP component. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Optimism

    Science.gov (United States)

    Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.

    2010-01-01

    Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998

  11. The biogeochemical iron cycle and astrobiology

    Science.gov (United States)

    Schröder, Christian; Köhler, Inga; Muller, Francois L. L.; Chumakov, Aleksandr I.; Kupenko, Ilya; Rüffer, Rudolf; Kappler, Andreas

    2016-12-01

    Biogeochemistry investigates chemical cycles which influence or are influenced by biological activity. Astrobiology studies the origin, evolution and distribution of life in the universe. The biogeochemical Fe cycle has controlled major nutrient cycles such as the C cycle throughout geological time. Iron sulfide minerals may have provided energy and surfaces for the first pioneer organisms on Earth. Banded iron formations document the evolution of oxygenic photosynthesis. To assess the potential habitability of planets other than Earth one looks for water, an energy source and a C source. On Mars, for example, Fe minerals have provided evidence for the past presence of liquid water on its surface and would provide a viable energy source. Here we present Mössbauer spectroscopy investigations of Fe and C cycle interactions in both ancient and modern environments. Experiments to simulate the diagenesis of banded iron formations indicate that the formation of ferrous minerals depends on the amount of biomass buried with ferric precursors rather than on the atmospheric composition at the time of deposition. Mössbauer spectra further reveal the mutual stabilisation of Fe-organic matter complexes against mineral transformation and decay of organic matter into CO2. This corresponds to observations of a `rusty carbon sink' in modern sediments. The stabilisation of Fe-organic matter complexes may also aid transport of particulate Fe in the water column while having an adverse effect on the bioavailability of Fe. In the modern oxic ocean, Fe is insoluble and particulate Fe represents an important source. Collecting that particulate Fe yields small sample sizes that would pose a challenge for conventional Mössbauer experiments. We demonstrate that the unique properties of the beam used in synchrotron-based Mössbauer applications can be utilized for studying such samples effectively. Reactive Fe species often occur in amorphous or nanoparticulate form in the environment and

  12. The biogeochemical iron cycle and astrobiology

    Energy Technology Data Exchange (ETDEWEB)

    Schröder, Christian, E-mail: christian.schroeder@stir.ac.uk [University of Stirling, Biological and Environmental Sciences, School of Natural Sciences (United Kingdom); Köhler, Inga [Eberhard Karls University of Tübingen, Geomicrobiology, Centre for Applied Geoscience (Germany); Muller, Francois L. L. [Qatar University, Department of Biological and Environmental Sciences (Qatar); Chumakov, Aleksandr I.; Kupenko, Ilya; Rüffer, Rudolf [ESRF-The European Synchrotron (France); Kappler, Andreas [Eberhard Karls University of Tübingen, Geomicrobiology, Centre for Applied Geoscience (Germany)

    2016-12-15

    Biogeochemistry investigates chemical cycles which influence or are influenced by biological activity. Astrobiology studies the origin, evolution and distribution of life in the universe. The biogeochemical Fe cycle has controlled major nutrient cycles such as the C cycle throughout geological time. Iron sulfide minerals may have provided energy and surfaces for the first pioneer organisms on Earth. Banded iron formations document the evolution of oxygenic photosynthesis. To assess the potential habitability of planets other than Earth one looks for water, an energy source and a C source. On Mars, for example, Fe minerals have provided evidence for the past presence of liquid water on its surface and would provide a viable energy source. Here we present Mössbauer spectroscopy investigations of Fe and C cycle interactions in both ancient and modern environments. Experiments to simulate the diagenesis of banded iron formations indicate that the formation of ferrous minerals depends on the amount of biomass buried with ferric precursors rather than on the atmospheric composition at the time of deposition. Mössbauer spectra further reveal the mutual stabilisation of Fe-organic matter complexes against mineral transformation and decay of organic matter into CO{sub 2}. This corresponds to observations of a ‘rusty carbon sink’ in modern sediments. The stabilisation of Fe-organic matter complexes may also aid transport of particulate Fe in the water column while having an adverse effect on the bioavailability of Fe. In the modern oxic ocean, Fe is insoluble and particulate Fe represents an important source. Collecting that particulate Fe yields small sample sizes that would pose a challenge for conventional Mössbauer experiments. We demonstrate that the unique properties of the beam used in synchrotron-based Mössbauer applications can be utilized for studying such samples effectively. Reactive Fe species often occur in amorphous or nanoparticulate form in the

  13. Optimization

    CERN Document Server

    Pearce, Charles

    2009-01-01

    Focuses on mathematical structure, and on real-world applications. This book includes developments in several optimization-related topics such as decision theory, linear programming, turnpike theory, duality theory, convex analysis, and queuing theory.

  14. Conformational analysis of large and highly disulfide-stabilized proteins by integrating online electrochemical reduction into an optimized H/D exchange mass spectrometry workflow.

    Science.gov (United States)

    Trabjerg, Esben; Jakobsen, Rasmus U; Mysling, Simon; Christensen, Søren; Jørgensen, Thomas J D; Rand, Kasper D

    2015-09-01

    Analysis of disulfide-bonded proteins by hydrogen/deuterium exchange mass spectrometry (HDX-MS) requires effective and rapid reduction of disulfide bonds before enzymatic digestion in order to increase sequence coverage. In a conventional HDX-MS workflow, disulfide bonds are reduced chemically by addition of a reducing agent to the quench solution (e.g., tris(2-carboxyethyl)phosphine (TCEP)). The chemical reduction, however, is severely limited under quenched conditions due to a narrow time window as well as low pH and temperature. Here, we demonstrate the real-world applicability of integrating electrochemical reduction into an online HDX-MS workflow. We have optimized the electrochemical reduction efficiency during HDX-MS analysis of two particularly challenging disulfide stabilized proteins: a therapeutic IgG1-antibody and nerve growth factor-β (NGF). Several different parameters (flow rate and applied square wave potential, as well as the type of labeling and quench buffer) were investigated, and the optimized workflow increased the sequence coverage of NGF from 46% with chemical reduction to 99%, when electrochemical reduction was applied. Additionally, the optimized workflow also enabled a similar high sequence coverage of 96% and 87% for the heavy and light chain of the IgG1-antibody, respectively. The presented results demonstrate the successful electrochemical reduction during HDX-MS analysis of both a small exceptional tightly disulfide-bonded protein (NGF) as well as the largest protein attempted to date (IgG1-antibody). We envision that online electrochemical reduction is poised to decrease the complexity of sample handling and increase the versatility of the HDX-MS technique.

  15. Mathematical optimization techniques for managing selective catalytic reduction for a fleet of coal-fired power plants

    Science.gov (United States)

    Alanis Pena, Antonio Alejandro

    Major commercial electricity generation is done by burning fossil fuels out of which coal-fired power plants produce a substantial quantity of electricity worldwide. The United States has large reserves of coal, and it is cheaply available, making it a good choice for the generation of electricity on a large scale. However, one major problem associated with using coal for combustion is that it produces a group of pollutants known as nitrogen oxides (NO x). NOx are strong oxidizers and contribute to ozone formation and respiratory illness. The Environmental Protection Agency (EPA) regulates the quantity of NOx emitted to the atmosphere in the United States. One technique coal-fired power plants use to reduce NOx emissions is Selective Catalytic Reduction (SCR). SCR uses layers of catalyst that need to be added or changed to maintain the required performance. Power plants do add or change catalyst layers during temporary shutdowns, but it is expensive. However, many companies do not have only one power plant, but instead they can have a fleet of coal-fired power plants. A fleet of power plants can use EPA cap and trade programs to have an outlet NOx emission below the allowances for the fleet. For that reason, the main aim of this research is to develop an SCR management mathematical optimization methods that, with a given set of scheduled outages for a fleet of power plants, minimizes the total cost of the entire fleet of power plants and also maintain outlet NO x below the desired target for the entire fleet. We use a multi commodity network flow problem (MCFP) that creates edges that represent all the SCR catalyst layers for each plant. This MCFP is relaxed because it does not consider average daily NOx constraint, and it is solved by a binary integer program. After that, we add the average daily NOx constraint to the model with a schedule elimination constraint (MCFPwSEC). The MCFPwSEC eliminates, one by one, the solutions that do not satisfy the average daily

  16. Optimal energy options under Clean Development Mechanism: Renewable energy projects for sustainable development and carbon emission reduction

    Science.gov (United States)

    Gilau, Asmerom M.

    This dissertation addresses two distinct objectives; designing cost-effective renewable energy powered projects including seawater reverse osmosis (SWRO), aquaculture, and ice-making plant, and analyzing the cost-effectiveness of these projects in achieving low abatement costs and promoting sustainable developments under the Clean Development Mechanism. The results of SWRO analysis show that a wind powered system is the least expensive and a PV powered system the most expensive, with finished water costs of about 0.50 /m3 and 1.00 /m3, respectively. By international standards, these costs are competitive. The results of renewable energy powered commercial tilapia production indicate that a wind-diesel system has high potential for intensive tilapia production as well as carbon dioxide emission reductions. The study also investigates aeration failures in renewable energy powered tilapia production systems. With respect to the ice-making plant, unlike previous studies which consider nighttime operation only, we have found that a nighttime PV powered ice-making system is more expensive (1/kWh) than daytime ice-making system (0.70/kWh). Our optimal energy options analysis at project scale which includes SWRO, ice-making plant and household energy consumption for about 100 households shows that compared to diesel only energy option, PV-D, W-D, and PV-W-D hybrids are very cost-effective energy options. Moreover, energy options with high levels of renewable energy including 100% renewables have the lowest net present cost and they are already cost-effective without CDM. On the other hand, while the removal of about 87% carbon dioxide emissions could be achieved at negative cost, initial investment could increase by a factor of 40, which is one of the primary barriers hindering wider renewable energy applications in developing countries. Thus in order to increase developing countries' participation in the carbon market, CDM policy should shift from a purely market oriented

  17. Assimilation of Sea Color Data Into A Three Dimensional Biogeochemical Model: Sensitivity Experiments

    Science.gov (United States)

    Echevin, V.; Levy, M.; Memery, L.

    The assimilation of two dimensional sea color data fields into a 3 dimensional coupled dynamical-biogeochemical model is performed using a 4DVAR algorithm. The biogeochemical model includes description of nitrates, ammonium, phytoplancton, zooplancton, detritus and dissolved organic matter. A subset of the biogeochemical model poorly known parameters (for example,phytoplancton growth, mortality,grazing) are optimized by minimizing a cost function measuring misfit between the observations and the model trajectory. Twin experiments are performed with an eddy resolving model of 5 km resolution in an academic configuration. Starting from oligotrophic conditions, an initially unstable baroclinic anticyclone splits into several eddies. Strong vertical velocities advect nitrates into the euphotic zone and generate a phytoplancton bloom. Biogeochemical parameters are perturbed to generate surface pseudo-observations of chlorophyll,which are assimilated in the model in order to retrieve the correct parameter perturbations. The impact of the type of measurement (quasi-instantaneous, daily mean, weekly mean) onto the retrieved set of parameters is analysed. Impacts of additional subsurface measurements and of errors in the circulation are also presented.

  18. Linking soil and sediment properties for research on biogeochemical cycles

    Science.gov (United States)

    Kuhn, Nikolaus J.

    2013-04-01

    Conventional perspectives on soil erosion include the on-site damage to soil and reductions in crop yield, as well as the resulting off-site effects on water quality, runoff and sediment loads in rivers. Our evolving understanding of the Earth System has added a new dimension to the role of soil erosion within the global geochemical cycles. First, the relevance of soil as a nutrient and Carbon (C) pool was recognized. Initially, the role of soils in the global C cycle was largely considered to be limited to a vertical exchange of greenhouse house gases (GHG) between vegetation, soil and atmosphere and thus mostly studied by soil scientists, plant ecologists and climatologists. Even Critical Zone research focused mostly on weathering and regolith properties and ignored lateral fluxes of dissolved or particulate organic matter. Since the late 1990s, a wider role of soils in biogeochemical cycles has emerged. Recent estimates place the lateral movement of C between soil and sediment pools in terrestrial ecosystems (including rivers and lakes) at approximately 0.6 to 1.5 Gt per year. Some of the eroded C is replaced by photosynthesis from the atmosphere, but at a cost of additional emissions, for example due to fertilizer production. The long-term fate of the eroded and deposited soil organic matter is subject to an open debate and suffers from a lack of reliable spatial information on lateral C fluxes and its subsequent fate in terrestrial ecosystems. The connection between soil C pool, GHG emissions and erosion illustrates the relevance of surface processes for the C fluxes between Earth's spheres. Accordingly, soil is now considered as mobile system to make accurate predictions about the consequences of global change for terrestrial biogeochemical cycles and climate feedbacks. This expanded perspective on soils as dynamic pool of weathering regolith, sediment, nutrients and C at the interface between the geospheres requires the analysis of relevant soil properties

  19. Engineering Pseudomonas stutzeri as a biogeochemical biosensor

    Science.gov (United States)

    Boynton, L.; Cheng, H. Y.; Del Valle, I.; Masiello, C. A.; Silberg, J. J.

    2016-12-01

    Biogeochemical cycles are being drastically altered as a result of anthropogenic activities, such as the burning of fossil fuels and the industrial production of ammonia. We know microbes play a major part in these cycles, but the extent of their biogeochemical roles remains largely uncharacterized due to inadequacies with culturing and measurement. While metagenomics and other -omics methods offer ways to reconstruct microbial communities, these approaches can only give an indication of the functional roles of microbes in a community. These -omics approaches are rapidly being expanded to the point of outpacing our knowledge of functional genes, which highlights an inherent need for analytical methods that non-invasively monitor Earth's processes in real time. Here we aim to exploit synthetic biology methods in order to engineer a ubiquitous denitrifying microbe, Pseudomonas stutzeri that can act as a biosensor in soil and marine environments. By using an easily cultivated microbe that is also common in many environments, we hope to develop a tool that allows us to zoom in on specific aspects of the nitrogen cycle. In order to monitor processes occurring at the genetic level in environments that cannot be resolved with fluorescence-based methods, such as soils, we have developed a system that instead relies on gas production by engineered microbial biosensors. P. stutzeri has been successfully engineered to release a gas, methyl bromide, which can continuously and non-invasively be measured by GC-MS. Similar to using Green Fluorescent Protein, GFP, in the biological sciences, the gene controlling gas production can be linked to those involved in denitrification, thereby creating a quantifiable gas signal that is correlated with microbial activity in the soil. Synthetically engineered microbial biosensors could reveal key aspects of metabolism in soil systems and offer a tool for characterizing the scope and degree of microbial impact on major biogeochemical cycles.

  20. Identification of biogeochemical hot spots using time-lapse hydrogeophysics

    Science.gov (United States)

    Franz, T. E.; Loecke, T.; Burgin, A.

    2016-12-01

    The identification and monitoring of biogeochemical hot spots and hot moments is difficult using point based sampling techniques and sensors. Without proper monitoring and accounting of water, energy, and trace gas fluxes it is difficult to assess the environmental footprint of land management practices. One key limitation is optimal placement of sensors/chambers that adequately capture the point scale fluxes and thus a reasonable integration to landscape scale flux. In this work we present time-lapse hydrogeophysical imaging at an old agricultural field converted into a wetland mitigation bank near Dayton, Ohio. While the wetland was previously instrumented with a network of soil sensors and surface chambers to capture a suite of state variables and fluxes, we hypothesize that time-lapse hydrogeophysical imaging is an underutilized and critical reconnaissance tool for effective network design and landscape scaling. Here we combine the time-lapse hydrogeophysical imagery with the multivariate statistical technique of Empirical Orthogonal Functions (EOF) in order to isolate the spatial and temporal components of the imagery. Comparisons of soil core information (e.g. soil texture, soil carbon) from around the study site and organized within like spatial zones reveal statistically different mean values of soil properties. Moreover, the like spatial zones can be used to identify a finite number of future sampling locations, evaluation of the placement of existing sensors/chambers, upscale/downscale observations, all of which are desirable techniques for commercial use in precision agriculture. Finally, we note that combining the EOF analysis with continuous monitoring from point sensors or remote sensing products may provide a robust statistical framework for scaling observations through time as well as provide appropriate datasets for use in landscape biogeochemical models.

  1. Meet the Editor: Global Biogeochemical Cycles

    Science.gov (United States)

    Kumar, Mohi

    Meinrat Andreae was named the editor of the AGU's journal Global Biogeochemical Cycles last year.Andreae, director of the biogeochemistry department at the Max Plank Institute for Chemistry (MPIC), located in Mainz, Germany said that he plans to maintain the journal as a resource that highlights the broad spectrum of interdisciplinary themes that showcase the interactions between the biosphere and the geosphere. “Our special niche is in the field of larger-scale, more integrative studies that have global scope,” he explained.

  2. Biogeochemical processes in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Gaye-Haake, B.; Guptha, M.V.S.; Murty, V.S.N.; Ittekkot, V.

    of dustfromtheArabianPeninsula,SomaliandThar Deep-Sea Research II 52 Editorial Biogeochemical Processes in This DSR II volume presents selected papers froman‘‘InternationalWorkshoponbiogeochem- ical processes in the northern Indian Ocean’’ coorganized...) the southern fan area via active deep-sea channels. The Of the 16 papers contained in this volume 11 erosion and convective overturn. Summer mon- desertstotheArabianSea.ThepaperbySchu¨ssler ARTICLE IN PRESS deal with the Arabian Sea, 2 with the Bay of Bengal...

  3. Disturbance decouples biogeochemical cycles across forests of the southeastern US

    Science.gov (United States)

    Ashley D. Keiser; Jennifer D. Knoepp; Mark A. Bradford

    2016-01-01

    Biogeochemical cycles are inherently linked through the stoichiometric demands of the organisms that cycle the elements. Landscape disturbance can alter element availability and thus the rates of biogeochemical cycling. Nitrification is a fundamental biogeochemical process positively related to plant productivity and nitrogen loss from soils to aquatic systems, and the...

  4. 广义快子系统的H∞最优模型降阶%H∞ Optimal Model Reduction for Singular Fast Subsystems

    Institute of Scientific and Technical Information of China (English)

    王静; 张庆灵; 刘万泉; 周越

    2005-01-01

    In this paper, H∞ optimal model reduction for singular fast subsystems will be inves-tigated. First, error system is established to measure the error magnitude between the original andreduced systems, and it is demonstrated that the new feature for model reduction of singular systemsis to make H∞ norm of the error system finite and minimal. The necessary and sufficient conditionis derived for the existence of the H∞ suboptimal model reduction problem. Next, we give an exactand practicable algorithm to get the parameters of the reduced subsystems by applying the matrixtheory. Meanwhile, the reduced system may be also impulsive. The advantages of the proposedalgorithm are that it is more flexible in a straight-forward way without much extra computation, andthe order of the reduced systems is as minimal as possible. Finally, one illustrative example is givento illustrate the effectiveness of the proposed model reduction approach.

  5. Flow ripple reduction of an axial piston pump by a combination of cross-angle and pressure relief grooves: Analysis and optimization

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Bing; Ye, Shaogan; Zhang, Junhui; Zhang, Chunfeng [Zhejiang University, Hangzhou (China)

    2016-06-15

    This paper investigates the potential of flow ripple reduction of an axial piston pump by a combination of cross-angle and pressure relief grooves. A dynamic model is developed to analyze the pumping dynamics of the pump and validated by experimental results. The effects of cross-angle on the flow ripples in the outlet and inlet ports, and the piston chamber pressure are investigated. The effects of pressure relief grooves on the optimal solutions obtained by a multi-objective optimization method are identified. A sensitivity analysis is performed to investigate the sensitivity of cross-angle to different working conditions. The results reveal that the flow ripples from the optimal solutions are smaller using the cross-angle and pressure relief grooves than those using the cross-angle and ordinary precompression and decompression angles and the cross-angle can be smaller. In addition, when the optimal design is used, the outlet flow ripples sensitivity can be reduced significantly.

  6. Influence of water column dynamics on sulfide oxidation and other major biogeochemical processes in the chemocline of Mariager Fjord (Denmark)

    DEFF Research Database (Denmark)

    Zopfi, J.; Ferdelman, TG; Jørgensen, BB

    2001-01-01

    Major electron donors (H2S, NH4+, Mn2+, Fe2+) and accepters (O-2, NO3-, Mn(IV), Fe(III)), process rates ((SO42-)-S-35 reduction, dark (CO2)-C-14 fixation) and vertical fluxes were investigated to quantify the dominant biogeochemical processes at the chemocline of a shallow brackish fjord. Under s...

  7. Astronomical Forcing of Salt Marsh Biogeochemical Cascades

    Science.gov (United States)

    Morris, J. T.; Sundberg, K.

    2008-12-01

    Astronomically forced changes in the hydroperiod of a salt marsh affect the rate of marsh primary production leading to a biogeochemical cascade. For example, salt marsh primary production and biogeochemical cycles in coastal salt marshes are sensitive to the 18.6-year lunar nodal cycle, which alters the tidal amplitude by about 5 cm. For marshes that are perched high in the tidal frame, a relatively small increase in tidal amplitude and flooding lowers sediment salinity and stimulates primary production. Porewater sulfide concentrations are positively correlated with tidal amplitude and vary on the same cycle as primary production. Soluble reactive phosphate and ammonium concentrations in pore water also vary on this 18.6- year cycle. Phosphate likely responds to variation in the reaction of sulfide with iron-phosphate compounds, while the production of ammonium in sediments is coupled to the activity of diazotrophs that are carbon- limited and, therefore, are regulated by primary productivity. Ammonium also would accumulate when sulfides block nitrification. These dependencies work as a positive feedback between primary production and nutrient supply and are predictive of the near-term effects of sea-level rise.

  8. Cyclic biogeochemical processes and nitrogen fate beneath a subtropical stormwater infiltration basin

    Science.gov (United States)

    O'Reilly, Andrew M.; Chang, Ni-Bin; Wanielista, Martin P.

    2012-01-01

    A stormwater infiltration basin in north–central Florida, USA, was monitored from 2007 through 2008 to identify subsurface biogeochemical processes, with emphasis on N cycling, under the highly variable hydrologic conditions common in humid, subtropical climates. Cyclic variations in biogeochemical processes generally coincided with wet and dry hydrologic conditions. Oxidizing conditions in the subsurface persisted for about one month or less at the beginning of wet periods with dissolved O2 and NO3- showing similar temporal patterns. Reducing conditions in the subsurface evolved during prolonged flooding of the basin. At about the same time O2 and NO3- reduction concluded, Mn, Fe and SO42- reduction began, with the onset of methanogenesis one month later. Reducing conditions persisted up to six months, continuing into subsequent dry periods until the next major oxidizing infiltration event. Evidence of denitrification in shallow groundwater at the site is supported by median NO3-–N less than 0.016 mg L-1, excess N2 up to 3 mg L-1 progressively enriched in δ15N during prolonged basin flooding, and isotopically heavy δ15N and δ18O of NO3- (up to 25‰ and 15‰, respectively). Isotopic enrichment of newly infiltrated stormwater suggests denitrification was partially completed within two days. Soil and water chemistry data suggest that a biogeochemically active zone exists in the upper 1.4 m of soil, where organic carbon was the likely electron donor supplied by organic matter in soil solids or dissolved in infiltrating stormwater. The cyclic nature of reducing conditions effectively controlled the N cycle, switching N fate beneath the basin from NO3- leaching to reduction in the shallow saturated zone. Results can inform design of functionalized soil amendments that could replace the native soil in a stormwater infiltration basin and mitigate potential NO3- leaching to groundwater by replicating the biogeochemical conditions under the observed basin.

  9. Reanalysis of biogeochemical properties in the Mediterranean Sea

    Science.gov (United States)

    Cossarini, Gianpiero; Teruzzi, Anna; Salon, Stefano; Solidoro, Cosimo

    2014-05-01

    In the 3D variational (3DVAR) assimilation approach the error covariance matrix can be decomposed in a series of operators. The decomposition makes the 3DVAR particularly suitable for marine biogeochemistry data assimilation, because of the reduced computational costs of the method and its modularity, which allows to define the covariance among the biogeochemical variables in a specific operator. In the present work, the results of 3DVAR assimilation of surface chlorophyll concentration in a multi-annual simulation of the Mediterranean Sea biogeochemistry are presented. The assimilated chlorophyll concentrations are obtained from satellite observations (Volpe et al. 2012). The multi-annual simulation is carried out using the OPATM-BFM model (Lazzari et al. 2012), which describes the low trophic web dynamics and is offline coupled with the MFS physical model (Oddo et al. 2009). In the OPATM-BFM four types of phytoplankton are simulated in terms of their content in carbon, nitrogen, phosphorous, silicon and chlorophyll. In the 3DVAR the error covariance matrix has been decomposed in three different operators, which account for the vertical, the horizontal and the biogeochemical covariance (Teruzzi et al. 2014). The biogeochemical operator propagates the result of the assimilation to the OPATM-BFM variables, providing innovation for the components of the four phytoplankton types. The biogeochemical covariance has been designed supposing that the assimilation preserves the physiological status and the relative abundances of phytoplankton types. Practically, the assimilation preserves the internal quotas of the components for each phytoplankton as long as the optimal growth rate condition are maintained. The quotas preservation is not applied when the phytoplankton is in severe declining growth phase, and the correction provided by the assimilation is set equal to zero. Moreover, the relative abundances among the phytoplankton functional types are preserved. The 3DVAR

  10. Diel biogeochemical processes in terrestrial waters

    Science.gov (United States)

    Compiled and Edited by Nimick, David A.; Gammons, Christopher H.

    2011-01-01

    Many biogeochemical processes in rivers and lakes respond to the solar photocycle and produce persistent patterns of measureable phenomena that exhibit a day-night, or 24-h, cycle. Despite a large body of recent literature, the mechanisms responsible for these diel fluctuations are widely debated, with a growing consensus that combinations of physical, chemical, and biological processes are involved. These processes include streamflow variation, photosynthesis and respiration, plant assimilation, and reactions involving photochemistry, adsorption and desorption, and mineral precipitation and dissolution. Diel changes in streamflow and water properties such as temperature, pH, and dissolved oxygen concentration have been widely recognized, and recently, diel studies have focused more widely by considering other constituents such as dissolved and particulate trace metals, metalloids, rare earth elements, mercury, organic matter, dissolved inorganic carbon (DIC), and nutrients. The details of many diel processes are being studied using stable isotopes, which also can exhibit diel cycles in response to microbial metabolism, photosynthesis and respiration, or changes in phase, speciation, or redox state. In addition, secondary effects that diel cycles might have, for example, on biota or in the hyporheic zone are beginning to be considered. This special issue is composed primarily of papers presented at the topical session "Diurnal Biogeochemical Processes in Rivers, Lakes, and Shallow Groundwater" held at the annual meeting of the Geological Society of America in October 2009 in Portland, Oregon. This session was organized because many of the growing number of diel studies have addressed just a small part of the full range of diel cycling phenomena found in rivers and lakes. This limited focus is understandable because (1) fundamental aspects of many diel processes are poorly understood and require detailed study, (2) the interests and expertise of individual

  11. Data and Model Uncertainties associated with Biogeochemical Groundwater Remediation and their impact on Decision Analysis

    Science.gov (United States)

    Pandey, S.; Vesselinov, V. V.; O'Malley, D.; Karra, S.; Hansen, S. K.

    2016-12-01

    Models and data are used to characterize the extent of contamination and remediation, both of which are dependent upon the complex interplay of processes ranging from geochemical reactions, microbial metabolism, and pore-scale mixing to heterogeneous flow and external forcings. Characterization is wrought with important uncertainties related to the model itself (e.g. conceptualization, model implementation, parameter values) and the data used for model calibration (e.g. sparsity, measurement errors). This research consists of two primary components: (1) Developing numerical models that incorporate the complex hydrogeology and biogeochemistry that drive groundwater contamination and remediation; (2) Utilizing novel techniques for data/model-based analyses (such as parameter calibration and uncertainty quantification) to aid in decision support for optimal uncertainty reduction related to characterization and remediation of contaminated sites. The reactive transport models are developed using PFLOTRAN and are capable of simulating a wide range of biogeochemical and hydrologic conditions that affect the migration and remediation of groundwater contaminants under diverse field conditions. Data/model-based analyses are achieved using MADS, which utilizes Bayesian methods and Information Gap theory to address the data/model uncertainties discussed above. We also use these tools to evaluate different models, which vary in complexity, in order to weigh and rank models based on model accuracy (in representation of existing observations), model parsimony (everything else being equal, models with smaller number of model parameters are preferred), and model robustness (related to model predictions of unknown future states). These analyses are carried out on synthetic problems, but are directly related to real-world problems; for example, the modeled processes and data inputs are consistent with the conditions at the Los Alamos National Laboratory contamination sites (RDX and

  12. Nutrient Legacies and Time Lags: Understanding Catchment Biogeochemical Responses in Anthropogenic Landscapes

    Science.gov (United States)

    Van Meter, K. J.; Basu, N. B.

    2014-12-01

    Human modification of the nitrogen (N) cycle has resulted in increased flows of reactive N, with some suggesting that planetary boundaries for maintaining human and ecosystem health have been exceeded. Persistence of large hypoxic zones in inland and coastal waters created by elevated concentrations of nitrate is one of the most significant impacts of such increased flows. While the need to manage these flows is recognized, best management practices to reduce stream N concentrations have had only limited success. Some have attributed this lack of success to accumulation of legacy N stores from decades of fertilizer application. Here we introduce an unprecedented analysis of long-term soil data from the Mississippi River Basin (MRB) revealing significant increases in total N (TN) content. We show that TN accumulation for the MRB accounts for 43% of net anthropogenic N inputs, complementing previous work indicating an approximately 25% loss of net inputs as riverine output. These findings significantly reduce uncertainty associated with basin-level N retention and demonstrate the presence of N accumulation in the deeper subsurface of agricultural soils. The presence of such legacy N stores is utilized in the development of a conceptual framework for quantifying catchment-scale time lags based on both soil nutrient accumulations (biogeochemical legacy) and groundwater travel time distributions (hydrologic legacy). Time scales of change for stream nutrient concentrations are explored as a function of both natural and anthropogenic controls, from topography to spatial patterns of land-use change, and an optimization approach has been developed to determine maximum possible concentration reduction benefits within time frames of interest.

  13. Optimization of Micro Strip Array Antennas Using Hybrid Particle Swarm Optimizer with Breeding and Subpopulation for Maximum Side-Lobe Reduction

    Directory of Open Access Journals (Sweden)

    F. T. Bendimerad

    2008-12-01

    Full Text Available In this paper, a technique based on hybrid particle swarm optimiser with breeding and subpopulation is presented for optimal design of reconfigurable dual-beam linear array antennas and planar arrays. In the amplitudephase synthesis, the design of a reconfigurable dual-pattern antenna array is based on finding a common amplitude distribution that can generate either a pencil or sector beam power pattern, when the phase distribution of the array is modified appropriately. The goal of this study is to introduce the hybrid model to the electromagnetic community and demonstrate its great potential in electromagnetic optimizations.

  14. Optimal Placement of Capacitor Banks in order to Improvement of Voltage Profile and Loss Reduction Based on PSO

    Directory of Open Access Journals (Sweden)

    Noradin Ghadimi

    2012-04-01

    Full Text Available This study develops an optimal placement method in order to sizing and sitting of capacitor banks in IEEE 33 bus test system. The proposed method in order to optimization in this article is Particle Swarm Optimization and the objective function is composed of two parts. The most part of proposed objective function considers improvement of voltage profile and other part is active power losses of the system in nominal load of mention system. In order to use of Particle Swarm Optimization algorithm, at first, placement problem is written as an optimization problem which includes the objective function and constraints, and then to achieve the most favorite results, Particle Swarm Optimization (PSO method is applied to solve the problem. High performance of the proposed algorithm in mention system is verified by simulations in MATLAB software and in order to prove of feasibility of proposed method this optimization in three cases - one capacitor bank, two capacitor banks, and three capacitor banks- will accomplish.

  15. Biogeochemical patchiness at the sea surface

    Science.gov (United States)

    Mahadevan, A.; Campbell, J. W.

    2002-10-01

    The surface distributions of many tracers in the ocean are highly correlated in time and space on meso (~100 km) and smaller scales (refid="fig01" type="media">Figure 1). However, their characteristic scales of variability differ. Some variables like sea surface chlorophyll (Chl) are very fine-scaled or patchy, while others like sea surface temperature (SST) are not. We characterize the patchiness of a distribution quantitatively by the dependence of the variance V on the length scale L as V ~ Lp; smaller p corresponds to greater patchiness. Using scaling and a numerical model we show that patchiness, p, varies with the characteristic response time τ of the tracer to processes that alter its concentration in the upper ocean as p ~ log τ. This suggests that sea surface Chl is more patchy (has smaller p) than SST at mesoscales because the characteristic time scale of phytoplankton growth in response to the availability of nutrients is less than that for the equilibration of temperature in response to heat fluxes. Similarly, sea surface dissolved oxygen (O2) exhibits more fine-scaled variability than total dissolved inorganic carbon (TCO2) because O2 equilibrates with the atmosphere much more rapidly than TCO2. Tracers that are more patchy require higher resolution to model and sample; the sampling or model grid spacing required scales as exp(-1/log τ). The quantitative relationship between p and τ can be used to relate various biogeochemical distributions, particularly to those that are remotely sensed, and to deduce biogeochemical response times of various tracers or plankton species from the characteristics of their distributions in space or time.

  16. [Optimization of blood gas analysis in intensive care units : Reduction of preanalytical errors and improvement of workflow].

    Science.gov (United States)

    Kieninger, M; Zech, N; Mulzer, Y; Bele, S; Seemann, M; Künzig, H; Schneiker, A; Gruber, M

    2015-05-01

    Point of care testing with blood gas analysis (BGA) is an important factor for intensive care medicine. Continuous efforts to optimize workflow, improve safety for the staff and avoid preanalytical mistakes are important and should reflect quality management standards. In a prospective observational study it was investigated whether the implementation of a new system for BGA using labeled syringes and automated processing of the specimens leads to improvements compared to the previously used procedure. In a 4-week test period the time until receiving the final results of the BGA with the standard method used in the clinical routine (control group) was compared to the results in a second 4-week test period using the new labeled syringes and automated processing of the specimens (intervention group). In addition, preanalytical mistakes with both systems were checked during routine daily use. Finally, it was investigated whether a delay of 10 min between taking and analyzing the blood samples alters the results of the BGA. Preanalytical errors were frequently observed in the control group where non-deaerated samples were recorded in 87.3 % but in the intervention group almost all samples (98.9 %) were correctly deaerated. Insufficient homogenization due to omission of manual pivoting was seen in 83.2 % in the control group and in 89.9 % in the intervention group; however, in the intervention group the samples were homogenized automatically during the further analytical process. Although a survey among the staff revealed a high acceptance of the new system and a subjective improvement of workflow, a measurable gain in time after conversion to the new procedure could not be seen. The mean time needed for a complete analysis process until receiving the final results was 244 s in the intervention group and 201 s in the control group. A 10-min delay between taking and analyzing the blood samples led to a significant and clinically relevant elevation of the values for

  17. Statistical Optimization of process parameters for SiO2-Nickel nanocomposites by in-situ reduction

    Directory of Open Access Journals (Sweden)

    A.K.Pramanick

    2015-06-01

    Full Text Available The optimum combination of process parameters - temperature, time of reduction under nitrogen atmosphere and amount of NiCl2 was delineated to find the maximum yield of nanocrystallite Ni in the synthesized silica gel matrix. A statistically adequate regression equation, within 95% confidence limit was developed by carrying out a set of experiments within the framework of design of experiment. The regression equation is found to indicate the beneficial role of the temperature and time of reduction.

  18. Optimal Placement and Sizing of Distributed Generation And Capacitor Bank For Loss Reduction And Reliability Improvement In Distribution Systems

    OpenAIRE

    Reza Baghipourr; Seyyed Mehdi Hosseini

    2014-01-01

    In this paper optimum size and location of the capacitors and distributed generators (DGs) are determined for reliability improvement and power loss reduction using genetic algorithm (GA). The main innovation of this paper is using both DG and Capacitor for the reliability improvement and power loss reduction. For this purpose an objective function consisting of reliability cost, power loss cost and also DG's and capacitor's investment cost are considered. The effectiveness of the proposed me...

  19. STATISTICAL OPTIMIZATION OF AQUEOUS LEAF EXTRACT OF AERVA LANATA FOR CITRININ AND FUNGAL BIOMASS REDUCTION IN SUBMERGED FERMENTATION BY ASPERGILLUS NIGER USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    Ajaz Ahmad

    2013-12-01

    Full Text Available Citrinin, a nephrotoxic mycotoxin produced by several fungal strains belonging to the genera Penicillium, Aspergillus, and Monascus. Generally found in stored grains and after their harvest. The objective of the present investigation was to study the antimicrobial activity (anti-fungal of aqueous leaf extract of Aerva lanata and to optimize its conditions for the maximum inhibition of citrinin and fungal biomass by Aspergillus niger. Optimization of culture conditions was carried out using Box-Behnken method of response surface methodology. Extent of inhibition of citrinin was carried out using HPLC and reduction in fungal biomass was carried out using dry cell weight after comparing with controls. Optimized culture conditions as per the point prediction tool were found to be 11.27 mg/L for concentration of Aerva lanata extract, nine and half days of incubation period and temperature of 25.5 °C resulted in maximum inhibition of citrinin. These optimized values of tested parameters were and compared with control citrinin production (243.28 mg/L and dry cell weight production (362.28mg.An average of 87.77±1.21% inhibition of citrinin and 80.02±1.42% of dry cell weight was obtained in an optimized medium at 9.5th d of fermentation with 97.82 % and 96.21% validity, respectively.

  20. Analysis-Driven Design Optimization of a SMA-Based Slat-Cove Filler for Aeroacoustic Noise Reduction

    Science.gov (United States)

    Scholten, William; Hartl, Darren; Turner, Travis

    2013-01-01

    Airframe noise is a significant component of environmental noise in the vicinity of airports. The noise associated with the leading-edge slat of typical transport aircraft is a prominent source of airframe noise. Previous work suggests that a slat-cove filler (SCF) may be an effective noise treatment. Hence, development and optimization of a practical slat-cove-filler structure is a priority. The objectives of this work are to optimize the design of a functioning SCF which incorporates superelastic shape memory alloy (SMA) materials as flexures that permit the deformations involved in the configuration change. The goal of the optimization is to minimize the actuation force needed to retract the slat-SCF assembly while satisfying constraints on the maximum SMA stress and on the SCF deflection under static aerodynamic pressure loads, while also satisfying the condition that the SCF self-deploy during slat extension. A finite element analysis model based on a physical bench-top model is created in Abaqus such that automated iterative analysis of the design could be performed. In order to achieve an optimized design, several design variables associated with the current SCF configuration are considered, such as the thicknesses of SMA flexures and the dimensions of various components, SMA and conventional. Designs of experiment (DOE) are performed to investigate structural response to an aerodynamic pressure load and to slat retraction and deployment. DOE results are then used to inform the optimization process, which determines a design minimizing actuator forces while satisfying the required constraints.

  1. ENHANCEMENT OF VOLTAGE STABILITY AND REDUCTION OF POWER LOSS USING GENETIC ALGORITHM THROUGH OPTIMAL LOCATION OF SVC, TCSC AND UPFC

    Directory of Open Access Journals (Sweden)

    R.KALAIVANI

    2016-10-01

    Full Text Available Due to huge increase in power demand, power system network will lead to major problems such as voltage instability and voltage collapse in the power system. To overcome these problems, Flexible AC Transmission System (FACTS devices have been implemented in power system. By placing these devices in suitable locations, the power system can be operated far away from the instability point. In this paper, the optimal location and the ratings of FACTS devices such as Thyristor Controlled Series Capacitor (TCSC, Static VAR Compensator (SVC and Unified Power Flow Controller (UPFC are determined using Genetic Algorithm (GA. A multi objective optimization problem is formulated with the consideration of minimizing voltage stability index, real power loss and generator cost. Evolutionary algorithm such as GA is a population based search method is used for solving multi objective optimization problem that is capable of searching for multiple solutions concurrently in a single run and provide an optimal solution. It is observed from the results that the voltages stability index, real power loss and generator cost are reduced by optimally locating the FACTS devices in the power system. IEEE 14 bus and IEEE 57 bus systems are used to demonstrate the effectiveness of the proposed algorithm.

  2. Optimization of culture conditions to produce high yields of active Acetobacter sp. CCTCC M209061 cells for anti-Prelog reduction of prochiral ketones

    Directory of Open Access Journals (Sweden)

    Chen Xiao-Hong

    2011-11-01

    Full Text Available Abstract Background Chiral alcohols are widely used in the synthesis of chiral pharmaceuticals, flavors and functional materials and appropriate whole-cell biocatalysts offer a highly enantioselective, minimally polluting route to these valuable compounds. The recently isolated strain Acetobacter sp. CCTCC M209061 showed exclusive anti-Prelog stereoselectivity for the reduction of prochiral ketones, but the low biomass has limited its commercialization and industrial applications. To tackle this problem, the effects of medium components and culture conditions on the strain's growth and reduction activity were explored. Results By using a one-at-a-time method and a central composite rotatable design (CCRD, the optimal medium and culture conditions were found to be as follows: glucose 8.26 g/L, fructose 2.50 g/L, soy peptone 83.92 g/L, MnSO4·H2O 0.088 g/L, pH 5.70, 30°C and 10% (v/v inoculum. Under the above-mentioned conditions, the biomass after 30 h cultivation reached 1.10 ± 0.03 g/L, which was 9.5-fold higher than that obtained with basic medium. Also, the reduction activity towards 4'-chloroacetophenone was markedly enhanced to 39.49 ± 0.96 μmol/min/g from 29.34 ± 0.65 μmol/min/g, with the product e.e. being above 99%. Comparable improvements were also seen with the enantioselective bioreduction of 4-(trimethylsilyl-3-butyn-2-one to the key pharmaceutical precursor (R - 4-(trimethylsilyl-3-butyn-2-ol. Conclusions The biomass and reduction activity of Acetobacter sp. CCTCC M209061 can be greatly enhanced through the optimization strategy. This facilitates use of the strain in the anti-Prelog stereoselective reduction of prochiral ketones to enantiopure chiral alcohols as building blocks for many industries.

  3. Coupling among Microbial Communities, Biogeochemistry, and Mineralogy across Biogeochemical Facies

    Energy Technology Data Exchange (ETDEWEB)

    Stegen, James C.; Konopka, Allan; McKinely, Jim; Murray, Christopher J.; Lin, Xueju; Miller, Micah D.; Kennedy, David W.; Miller, Erin A.; Resch, Charles T.; Fredrickson, Jim K.

    2016-07-29

    Physical properties of sediments are commonly used to define subsurface lithofacies and these same physical properties influence subsurface microbial communities. This suggests an (unexploited) opportunity to use the spatial distribution of facies to predict spatial variation in biogeochemically relevant microbial attributes. Here, we characterize three biogeochemical facies—oxidized, reduced, and transition—within one lithofacies and elucidate relationships among facies features and microbial community biomass, diversity, and community composition. Consistent with previous observations of biogeochemical hotspots at environmental transition zones, we find elevated biomass within a biogeochemical facies that occurred at the transition between oxidized and reduced biogeochemical facies. Microbial diversity—the number of microbial taxa—was lower within the reduced facies and was well-explained by a combination of pH and mineralogy. Null modeling revealed that microbial community composition was influenced by ecological selection imposed by redox state and mineralogy, possibly due to effects on nutrient availability or transport. As an illustrative case, we predict microbial biomass concentration across a three-dimensional spatial domain by coupling the spatial distribution of subsurface biogeochemical facies with biomass-facies relationships revealed here. We expect that merging such an approach with hydro-biogeochemical models will provide important constraints on simulated dynamics, thereby reducing uncertainty in model predictions.

  4. Optimal Dark Current Reduction in Quantum Well 9 µm GaAs/AlGaAs Infrared Photodetectors with Improved Detectivity

    Directory of Open Access Journals (Sweden)

    Shahram M. Nejad

    2008-01-01

    Full Text Available In this research, an optimization approach is presented to decrease the dark current in GaAs/AlGaAs QWIPs. The dark current noise is reduced by increasing Al density in barriers, decreasing detector dimensions and increasing the periodic length of the structure. In addition, increasing the number of periods can reduce both the dark current and responsivity. Therefore, devices can be optimally designed through judicious choice of these parameters. An optimal photodetector structure is designed and simulated to achieve low dark current (11nA and detectivity of 1.4×1012cm(Hz1/2/W which is an order of magnitude greater than the present values.

  5. Biogeochemical Transport and Reaction Model (BeTR) v1

    Energy Technology Data Exchange (ETDEWEB)

    2016-04-18

    The Biogeochemical Transport and Reaction Model (BeTR) is a F90 code that enables reactive transport modeling in land modules of earth system models (e.g. CESM, ACME). The code adopts the Objective-Oriented-Design, and allows users to plug in their own biogeochemical (BGC) formulations/codes, and compare them to other existing BGC codes in those ESMs. The code takes information of soil physics variables, such as variables, such as temperature, moisture, soil density profile; water flow, etc., from a land model to track the movement of different chemicals in presence of biogeochemical reactions.

  6. Design of an optimized biomixture for the degradation of carbofuran based on pesticide removal and toxicity reduction of the matrix.

    Science.gov (United States)

    Chin-Pampillo, Juan Salvador; Ruiz-Hidalgo, Karla; Masís-Mora, Mario; Carazo-Rojas, Elizabeth; Rodríguez-Rodríguez, Carlos E

    2015-12-01

    Pesticide biopurification systems contain a biologically active matrix (biomixture) responsible for the accelerated elimination of pesticides in wastewaters derived from pest control in crop fields. Biomixtures have been typically prepared using the volumetric composition 50:25:25 (lignocellulosic substrate/humic component/soil); nonetheless, formal composition optimization has not been performed so far. Carbofuran is an insecticide/nematicide of high toxicity widely employed in developing countries. Therefore, the composition of a highly efficient biomixture (composed of coconut fiber, compost, and soil, FCS) for the removal of carbofuran was optimized by means of a central composite design and response surface methodology. The volumetric content of soil and the ratio coconut fiber/compost were used as the design variables. The performance of the biomixture was assayed by considering the elimination of carbofuran, the mineralization of (14)C-carbofuran, and the residual toxicity of the matrix, as response variables. Based on the models, the optimal volumetric composition of the FCS biomixture consists of 45:13:42 (coconut fiber/compost/soil), which resulted in minimal residual toxicity and ∼99% carbofuran elimination after 3 days. This optimized biomixture considerably differs from the standard 50:25:25 composition, which remarks the importance of assessing the performance of newly developed biomixtures during the design of biopurification systems.

  7. Consequences of climate change for biogeochemical cycling in forests of northeastern North America

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J.L.; Rustad, L.E. [United States Forest Service, Durham, NH (United States). Northern Research Station; Boyer, E.W. [Pennsylvania State Univ., University Park, PA (United States). School of Forest Resources; Christopher, S.F. [Buffalo State College, Buffalo, NY (United States). Great Lakes Center; Driscoll, C.T.; Kiekbusch, J. [Syracuse Univ., Syracuse, NY (United States). Dept. of Civil and Environmental Engineering; Fernandex, I.J. [Maine Univ., Orono, ME (United States). Dept. of Plant, Soil and Environmental Sciences; Groffman, P.M. [Cary Inst. of Ecosystem Studies, Millbrook, NY (United States); Houle, D. [Quebec Ministere des ressources naturelles et de la Faune, Ste Foy, PQ (Canada). Direction de la recherche forestiere; Ouranos, Montreal, PQ (Canada); Magill, A.H.; Ollinger, S.V. [New Hampshire Univ., Durham, NH (United States). Complex Systems Research Center; Mitchell, M.J. [State Univ. of New York, Syracuse, NY (United States). Dept. of Environmental and Forest Biology

    2009-02-15

    This paper examined the effects of climate change on the biogeochemical cycling of elements in forest ecosystems. The effects of climatic change on plant physiology, forest productivity and soil physical, chemical, and biological processes were evaluated. A case study used the quantitative biogeochemical PneT-BGC model to evaluate assumptions about the impacts of climatic change on a northern hardwood forest ecosystem. The study demonstrated an increase in net primary production as a result of a longer growing season, increases in nitrate leaching caused by increases in net mineralization and nitrification, and declines in mineral weathering as a result of soil moisture reductions. Changes in species composition, hydrology, and the length of the growing season will have have an impact on biogeochemical cycling. Further research is needed to investigate the influence of multiple simultaneous stressors; long-term carbon dioxide (CO{sub 2}) enrichment on vegetation; and changes in forest species composition. It was concluded that the impacts of extreme climatic events and other disturbances on forest ecosystems must also be evaluated. 174 refs., 2 figs.

  8. Simple parameter estimation for complex models — Testing evolutionary techniques on 3-dimensional biogeochemical ocean models

    Science.gov (United States)

    Mattern, Jann Paul; Edwards, Christopher A.

    2017-01-01

    Parameter estimation is an important part of numerical modeling and often required when a coupled physical-biogeochemical ocean model is first deployed. However, 3-dimensional ocean model simulations are computationally expensive and models typically contain upwards of 10 parameters suitable for estimation. Hence, manual parameter tuning can be lengthy and cumbersome. Here, we present four easy to implement and flexible parameter estimation techniques and apply them to two 3-dimensional biogeochemical models of different complexities. Based on a Monte Carlo experiment, we first develop a cost function measuring the model-observation misfit based on multiple data types. The parameter estimation techniques are then applied and yield a substantial cost reduction over ∼ 100 simulations. Based on the outcome of multiple replicate experiments, they perform on average better than random, uninformed parameter search but performance declines when more than 40 parameters are estimated together. Our results emphasize the complex cost function structure for biogeochemical parameters and highlight dependencies between different parameters as well as different cost function formulations.

  9. Evaluating enhanced sulfate reduction and optimized volatile fatty acids (VFA) composition in anaerobic reactor by Fe (III) addition.

    Science.gov (United States)

    Liu, Yiwen; Zhang, Yaobin; Ni, Bing-Jie

    2015-02-17

    Anaerobic reactors with ferric iron addition have been experimentally demonstrated to be able to simultaneously improve sulfate reduction and organic matter degradation during sulfate-containing wastewater treatment. In this work, a mathematical model is developed to evaluate the impact of ferric iron addition on sulfate reduction and organic carbon removal as well as the volatile fatty acids (VFA) composition in anaerobic reactor. The model is successfully calibrated and validated using independent long-term experimental data sets from the anaerobic reactor with Fe (III) addition under different operational conditions. The model satisfactorily describes the sulfate reduction, organic carbon removal and VFA production. Results show Fe (III) addition induces the microbial reduction of Fe (III) by iron reducing bacteria (IRB), which significantly enhances sulfate reduction by sulfate reducing bacteria (SRB) and subsequently changes the VFA composition to acetate-dominating effluent. Simultaneously, the produced Fe (II) from IRB can alleviate the inhibition of undissociated H2S on microorganisms through iron sulfide precipitation, resulting in further improvement of the performance. In addition, the enhancement on reactor performance by Fe (III) is found to be more significantly favored at relatively low organic carbon/SO4(2-) ratio (e.g., 1.0) than at high organic carbon/SO4(2-) ratio (e.g., 4.5). The Fe (III)-based process of this work can be easily integrated with a commonly used strategy for phosphorus recovery, with the produced sulfide being recovered and then deposited into conventional chemical phosphorus removal sludge (FePO4) to achieve FeS precipitation for phosphorus recovery while the required Fe (III) being acquired from the waste ferric sludge of drinking water treatment process, to enable maximum resource recovery/reuse while achieving high-rate sulfate removal.

  10. Optimal fleetwide emissions reductions for passenger ferries: an application of a mixed-integer nonlinear programming model for the New York-New Jersey Harbor.

    Science.gov (United States)

    Winebrake, James J; Corbett, James J; Wang, Chengfeng; Farrell, Alexander E; Woods, Pippa

    2005-04-01

    Emissions from passenger ferries operating in urban harbors may contribute significantly to emissions inventories and commuter exposure to air pollution. In particular, ferries are problematic because of high emissions of oxides of nitrogen (NOx) and particulate matter (PM) from primarily unregulated diesel engines. This paper explores technical solutions to reduce pollution from passenger ferries operating in the New York-New Jersey Harbor. The paper discusses and demonstrates a mixed-integer, non-linear programming model used to identify optimal control strategies for meeting NOx and PM reduction targets for 45 privately owned commuter ferries in the harbor. Results from the model can be used by policy-makers to craft programs aimed at achieving least-cost reduction targets.

  11. Reduction of fatigue loads on jacket substructure through blade design optimization for multi-megawatt wind turbines at 50 m water depths

    Science.gov (United States)

    Njomo Wandji, W.; Pavese, C.; Natarajan, A.; Zahle, F.

    2016-09-01

    This paper addresses the reduction of the fore-aft damage equivalent moment at the tower base for multi-megawatt offshore wind turbines mounted on jacket type substructures at 50 m water depths. The study investigates blade design optimization of a reference 10 MW wind turbine under standard wind conditions of onshore sites. The blade geometry and structure is optimized to yield a design that minimizes tower base fatigue loads without significant loss of power production compared to that of the reference setup. The resulting blade design is then mounted on a turbine supported by a jacket and placed under specific offshore site conditions. The new design achieves alleviate fatigue damage equivalent loads also in the jacket members, showing the possibility to prolong its design lifetime or to save material in comparison to the reference jacket. Finally, the results suggest additional benefit on the efficient design of other components such as the constituents of the nacelle.

  12. A state-space Bayesian framework for estimating biogeochemical transformations using time-lapse geophysical data

    Science.gov (United States)

    Chen, Jinsong; Hubbard, Susan S.; Williams, Kenneth H.; Pride, Steve; Li, Li; Steefel, Carl; Slater, Lee

    2009-08-01

    We develop a state-space Bayesian framework to combine time-lapse geophysical data with other types of information for quantitative estimation of biogeochemical parameters during bioremediation. We consider characteristics of end products of biogeochemical transformations as state vectors, which evolve under constraints of local environments through evolution equations, and consider time-lapse geophysical data as available observations, which could be linked to the state vectors through petrophysical models. We estimate the state vectors and their associated unknown parameters over time using Markov chain Monte Carlo sampling methods. To demonstrate the use of the state-space approach, we apply it to complex resistivity data collected during laboratory column biostimulation experiments that were poised to precipitate iron and zinc sulfides during sulfate reduction. We develop a petrophysical model based on sphere-shaped cells to link the sulfide precipitate properties to the time-lapse geophysical attributes and estimate volume fraction of the sulfide precipitates, fraction of the dispersed, sulfide-encrusted cells, mean radius of the aggregated clusters, and permeability over the course of the experiments. Results of the case study suggest that the developed state-space approach permits the use of geophysical data sets for providing quantitative estimates of end-product characteristics and hydrological feedbacks associated with biogeochemical transformations. Although tested here on laboratory column experiment data sets, the developed framework provides the foundation needed for quantitative field-scale estimation of biogeochemical parameters over space and time using direct, but often sparse wellbore data with indirect, but more spatially extensive geophysical data sets.

  13. Integrated control of emission reductions, energy-saving, and cost-benefit using a multi-objective optimization technique in the pulp and paper industry.

    Science.gov (United States)

    Wen, Zongguo; Xu, Chang; Zhang, Xueying

    2015-03-17

    Reduction of water pollutant emissions and energy consumption is regarded as a key environmental objective for the pulp and paper industry. The paper develops a bottom-up model called the Industrial Water Pollutant Control and Technology Policy (IWPCTP) based on an industrial technology simulation system and multiconstraint technological optimization. Five policy scenarios covering the business as usual (BAU) scenario, the structural adjustment (SA) scenario, the cleaner technology promotion (CT) scenario, the end-treatment of pollutants (EOP) scenario, and the coupling measures (CM) scenario have been set to describe future policy measures related to the development of the pulp and paper industry from 2010-2020. The outcome of this study indicates that the energy saving amount under the CT scenario is the largest, while that under the SA scenario is the smallest. Under the CT scenario, savings by 2020 include 70 kt/year of chemical oxygen demand (COD) emission reductions and savings of 7443 kt of standard coal, 539.7 ton/year of ammonia nitrogen (NH4-N) emission reductions, and savings of 7444 kt of standard coal. Taking emission reductions, energy savings, and cost-benefit into consideration, cleaner technologies like highly efficient pulp washing, dry and wet feedstock preparation, and horizontal continuous cooking, medium and high consistency pulping and wood dry feedstock preparation are recommended.

  14. Optimization of power control in the reduction of basal plane dislocations during PVT growth of 4H-SiC single crystals

    Science.gov (United States)

    Gao, B.; Kakimoto, K.

    2014-04-01

    The influence of power control on the multiplication of basal plane dislocations (BPDs) during PVT growth of 4H-SiC single crystals was studied by numerical modeling. Three sets of different power histories during growth were tested: continuously increasing power, continuously decreasing power, and constant power. The results show that optimization of the power history control is crucial for the reduction of basal plane dislocations during growth. If only low BPD density is concerned, then constant low power is the best choice. However, if both low BPD density and high growth rate are desirable, then concave continuously increasing power is the best choice.

  15. A flexibility-based method via the iterated improved reduction system and the cuckoo optimization algorithm for damage quantification with limited sensors

    Science.gov (United States)

    Zare Hosseinzadeh, Ali; Bagheri, Abdollah; Ghodrati Amiri, Gholamreza; Koo, Ki-Young

    2014-04-01

    In this paper, a novel and effective damage diagnosis algorithm is proposed to localize and quantify structural damage using incomplete modal data, considering the existence of some limitations in the number of attached sensors on structures. The damage detection problem is formulated as an optimization problem by computing static displacements in the reduced model of a structure subjected to a unique static load. The static responses are computed through the flexibility matrix of the damaged structure obtained based on the incomplete modal data of the structure. In the algorithm, an iterated improved reduction system method is applied to prepare an accurate reduced model of a structure. The optimization problem is solved via a new evolutionary optimization algorithm called the cuckoo optimization algorithm. The efficiency and robustness of the presented method are demonstrated through three numerical examples. Moreover, the efficiency of the method is verified by an experimental study of a five-story shear building structure on a shaking table considering only two sensors. The obtained damage identification results for the numerical and experimental studies show the suitable and stable performance of the proposed damage identification method for structures with limited sensors.

  16. A NOVEL OPTIMIZATION MODEL FOR SIMULTANEOUS COST-RISK REDUCTION IN MULTI-SUPPLIERS JUST-IN-TIME SYSTEMS

    Directory of Open Access Journals (Sweden)

    Faraj El Dabee

    2013-01-01

    Full Text Available In today’s competitive global markets, Just-in-Time (JIT is one of the main lean manufacturing approaches. It is used in organizations to improve performance and reduce costs and as a strategic core capability to ensure their market position. However, using JIT tightly couples various functions of the Supply Chain and increases the risk of propagating disruptions through the entire system. This study presents an ordering strategy for the supply of raw materials to the production system to meet customer satisfaction. A general model for cost-risk reduction is developed embracing multiple external and local backup suppliers. The outcomes from this model will be used to obtimise the simultaneous cost/risk reduction within JIT systems. The effectiveness of the developed model will be validated using a simplified example.

  17. Optimal Placement and Sizing of Distributed Generation And Capacitor Bank For Loss Reduction And Reliability Improvement In Distribution Systems

    Directory of Open Access Journals (Sweden)

    Reza Baghipourr

    2014-12-01

    Full Text Available In this paper optimum size and location of the capacitors and distributed generators (DGs are determined for reliability improvement and power loss reduction using genetic algorithm (GA. The main innovation of this paper is using both DG and Capacitor for the reliability improvement and power loss reduction. For this purpose an objective function consisting of reliability cost, power loss cost and also DG's and capacitor's investment cost are considered. The effectiveness of the proposed method is examined in the 10 and 33 bus test systems and comparative studies are conducted before and after DG and Capacitor installation in the test systems. The results obtained show the effectiveness of the proposed method.

  18. The Microbial Engines That Drive Earth's Biogeochemical Cycles

    National Research Council Canada - National Science Library

    Paul G. Falkowski; Tom Fenchel; Edward F. Delong

    2008-01-01

    .... Hence, although there is enormous genetic diversity in nature, there remains a relatively stable set of core genes coding for the major redox reactions essential for life and biogeochemical cycles...

  19. Biogeochemical Processes Regulating the Mobility of Uranium in Sediments

    Energy Technology Data Exchange (ETDEWEB)

    Belli, Keaton M.; Taillefert, Martial

    2016-07-01

    This book chapters reviews the latest knowledge on the biogeochemical processes regulating the mobility of uranium in sediments. It contains both data from the literature and new data from the authors.

  20. Experiences at Langley Research Center in the application of optimization techniques to helicopter airframes for vibration reduction

    Science.gov (United States)

    Murthy, T. Sreekanta; Kvaternik, Raymond G.

    1991-01-01

    A NASA/industry rotorcraft structural dynamics program known as Design Analysis Methods for VIBrationS (DAMVIBS) was initiated at Langley Research Center in 1984 with the objective of establishing the technology base needed by the industry for developing an advanced finite-element-based vibrations design analysis capability for airframe structures. As a part of the in-house activities contributing to that program, a study was undertaken to investigate the use of formal, nonlinear programming-based, numerical optimization techniques for airframe vibrations design work. Considerable progress has been made in connection with that study since its inception in 1985. This paper presents a unified summary of the experiences and results of that study. The formulation and solution of airframe optimization problems are discussed. Particular attention is given to describing the implementation of a new computational procedure based on MSC/NASTRAN and CONstrained function MINimization (CONMIN) in a computer program system called DYNOPT for the optimization of airframes subject to strength, frequency, dynamic response, and fatigue constraints. The results from the application of the DYNOPT program to the Bell AH-1G helicopter are presented and discussed.

  1. Effect of biogeochemical interactions on bioaccessibility of arsenic in soils of a former smelter site in Republic of Korea.

    Science.gov (United States)

    Yang, Kyung; Jeong, Seulki; Jho, Eun Hea; Nam, Kyoungphile

    2016-12-01

    The total concentration-based regulations for soil remediation do not consider the possible changes in bioaccessibility of remaining arsenic (As) in soils due to biogeochemical interactions after remediation. This study used As-contaminated soil and pore water samples that were collected from the rice paddy and forest/farmland located in the vicinity of a former smelter site in Republic of Korea to elucidate the changes in As bioaccessibility due to biogeochemical interactions. Bioaccessibility and chemical forms of As in soils were determined by using an in vitro method and sequential extraction, respectively, and soil microbial community was evaluated. Bioaccessibility of As in the rice paddy soil samples was higher than that in the forest/farmland soil samples. This could be attributed to relatively higher dependence of bioaccessible As in the rice paddy soils on the soil concentration of iron (Fe), aluminum, or manganese, which could lead to greater changes in bioaccessible As via reductive dissolution. The strong linear relationship (R (2) = 0.90, p value ≤0.001) between the pore water As and Fe concentrations, and the greater portion of bacterial species related to reductive dissolution of Fe oxides in the rice paddies can support the higher As bioaccessibility promoted by reductive dissolution. Therefore, it is necessary to consider the potential changes in the bioaccessible As due to biogeochemical interactions in remediation of As-contaminated soils, particularly when soils are likely to be reused under reductive dissolution-promoting conditions (e.g., flooded conditions).

  2. Redox regime shifts in microbially-mediated biogeochemical cycles

    Science.gov (United States)

    Bush, T.; Butler, I. B.; Free, A.; Allen, R. J.

    2015-02-01

    Understanding how the Earth's biogeochemical cycles respond to environmental change is a prerequisite for the prediction and mitigation of the effects of anthropogenic perturbations. Microbial populations mediate key steps in these cycles, yet are often crudely represented in biogeochemical models. Here, we show that microbial population dynamics can qualitatively affect the response of biogeochemical cycles to environmental change. Using simple and generic mathematical models, we find that nutrient limitations on microbial population growth can lead to regime shifts, in which the redox state of a biogeochemical cycle changes dramatically as the availability of a redox-controlling species, such as oxygen or acetate, crosses a threshold (a "tipping point"). These redox regime shifts occur in parameter ranges that are relevant to the sulfur and nitrogen cycles in the present-day natural environment, and may also have relevance to iron cycling in the iron-containing Proterozoic and Archean oceans. We show that redox regime shifts also occur in models with physically realistic modifications, such as additional terms, chemical states, or microbial populations. Our work reveals a possible new mechanism by which regime shifts can occur in nutrient-cycling ecosystems and biogeochemical cycles, and highlights the importance of considering microbial population dynamics in models of biogeochemical cycles.

  3. Redox regime shifts in microbially mediated biogeochemical cycles

    Science.gov (United States)

    Bush, T.; Butler, I. B.; Free, A.; Allen, R. J.

    2015-06-01

    Understanding how the Earth's biogeochemical cycles respond to environmental change is a prerequisite for the prediction and mitigation of the effects of anthropogenic perturbations. Microbial populations mediate key steps in these cycles, yet they are often crudely represented in biogeochemical models. Here, we show that microbial population dynamics can qualitatively affect the response of biogeochemical cycles to environmental change. Using simple and generic mathematical models, we find that nutrient limitations on microbial population growth can lead to regime shifts, in which the redox state of a biogeochemical cycle changes dramatically as the availability of a redox-controlling species, such as oxygen or acetate, crosses a threshold (a "tipping point"). These redox regime shifts occur in parameter ranges that are relevant to the present-day sulfur cycle in the natural environment and the present-day nitrogen cycle in eutrophic terrestrial environments. These shifts may also have relevance to iron cycling in the iron-containing Proterozoic and Archean oceans. We show that redox regime shifts also occur in models with physically realistic modifications, such as additional terms, chemical states, or microbial populations. Our work reveals a possible new mechanism by which regime shifts can occur in nutrient-cycling ecosystems and biogeochemical cycles, and highlights the importance of considering microbial population dynamics in models of biogeochemical cycles.

  4. BIOGEOCHEMICAL PROCESSES OF PHOSPHORUS AND SILICON IN SOUTHERN BOHAI SEA SURFACE SEDIMENTS

    Institute of Scientific and Technical Information of China (English)

    宋金明; 罗延馨; 吕晓霞; 李鹏程

    2002-01-01

    Based on the author's previously obtained results on P and Si forms in southern Bohai Sea surface sediments,this study mainly foucusing on the controlling facto rs, existence forms, and biogeochemical processes of P and Si showed that the transferable fo rms of phosphorus in sediments were mainly controlled by the mineralization of organic matters and the reduction of high-valence iron; whereas the transferable forms of silicon were possibly controlled by the dissolution and precipitation as well as biochemical processes of living organisms.

  5. Statistical model based iterative reconstruction in clinical CT systems. Part III. Task-based kV/mAs optimization for radiation dose reduction.

    Science.gov (United States)

    Li, Ke; Gomez-Cardona, Daniel; Hsieh, Jiang; Lubner, Meghan G; Pickhardt, Perry J; Chen, Guang-Hong

    2015-09-01

    For a given imaging task and patient size, the optimal selection of x-ray tube potential (kV) and tube current-rotation time product (mAs) is pivotal in achieving the maximal radiation dose reduction while maintaining the needed diagnostic performance. Although contrast-to-noise (CNR)-based strategies can be used to optimize kV/mAs for computed tomography (CT) imaging systems employing the linear filtered backprojection (FBP) reconstruction method, a more general framework needs to be developed for systems using the nonlinear statistical model-based iterative reconstruction (MBIR) method. The purpose of this paper is to present such a unified framework for the optimization of kV/mAs selection for both FBP- and MBIR-based CT systems. The optimal selection of kV and mAs was formulated as a constrained optimization problem to minimize the objective function, Dose(kV,mAs), under the constraint that the achievable detectability index d'(kV,mAs) is not lower than the prescribed value of d'R for a given imaging task. Since it is difficult to analytically model the dependence of d' on kV and mAs for the highly nonlinear MBIR method, this constrained optimization problem is solved with comprehensive measurements of Dose(kV,mAs) and d'(kV,mAs) at a variety of kV-mAs combinations, after which the overlay of the dose contours and d' contours is used to graphically determine the optimal kV-mAs combination to achieve the lowest dose while maintaining the needed detectability for the given imaging task. As an example, d' for a 17 mm hypoattenuating liver lesion detection task was experimentally measured with an anthropomorphic abdominal phantom at four tube potentials (80, 100, 120, and 140 kV) and fifteen mA levels (25 and 50-700) with a sampling interval of 50 mA at a fixed rotation time of 0.5 s, which corresponded to a dose (CTDIvol) range of [0.6, 70] mGy. Using the proposed method, the optimal kV and mA that minimized dose for the prescribed detectability level of d'R=16

  6. Proterozoic ocean redox and biogeochemical stasis

    Science.gov (United States)

    Reinhard, Christopher T.; Planavsky, Noah J.; Robbins, Leslie J.; Partin, Camille A.; Gill, Benjamin C.; Lalonde, Stefan V.; Bekker, Andrey; Konhauser, Kurt O.; Lyons, Timothy W.

    2013-01-01

    The partial pressure of oxygen in Earth’s atmosphere has increased dramatically through time, and this increase is thought to have occurred in two rapid steps at both ends of the Proterozoic Eon (∼2.5–0.543 Ga). However, the trajectory and mechanisms of Earth’s oxygenation are still poorly constrained, and little is known regarding attendant changes in ocean ventilation and seafloor redox. We have a particularly poor understanding of ocean chemistry during the mid-Proterozoic (∼1.8–0.8 Ga). Given the coupling between redox-sensitive trace element cycles and planktonic productivity, various models for mid-Proterozoic ocean chemistry imply different effects on the biogeochemical cycling of major and trace nutrients, with potential ecological constraints on emerging eukaryotic life. Here, we exploit the differing redox behavior of molybdenum and chromium to provide constraints on seafloor redox evolution by coupling a large database of sedimentary metal enrichments to a mass balance model that includes spatially variant metal burial rates. We find that the metal enrichment record implies a Proterozoic deep ocean characterized by pervasive anoxia relative to the Phanerozoic (at least ∼30–40% of modern seafloor area) but a relatively small extent of euxinic (anoxic and sulfidic) seafloor (less than ∼1–10% of modern seafloor area). Our model suggests that the oceanic Mo reservoir is extremely sensitive to perturbations in the extent of sulfidic seafloor and that the record of Mo and chromium enrichments through time is consistent with the possibility of a Mo–N colimited marine biosphere during many periods of Earth’s history. PMID:23515332

  7. Proterozoic ocean redox and biogeochemical stasis.

    Science.gov (United States)

    Reinhard, Christopher T; Planavsky, Noah J; Robbins, Leslie J; Partin, Camille A; Gill, Benjamin C; Lalonde, Stefan V; Bekker, Andrey; Konhauser, Kurt O; Lyons, Timothy W

    2013-04-02

    The partial pressure of oxygen in Earth's atmosphere has increased dramatically through time, and this increase is thought to have occurred in two rapid steps at both ends of the Proterozoic Eon (∼2.5-0.543 Ga). However, the trajectory and mechanisms of Earth's oxygenation are still poorly constrained, and little is known regarding attendant changes in ocean ventilation and seafloor redox. We have a particularly poor understanding of ocean chemistry during the mid-Proterozoic (∼1.8-0.8 Ga). Given the coupling between redox-sensitive trace element cycles and planktonic productivity, various models for mid-Proterozoic ocean chemistry imply different effects on the biogeochemical cycling of major and trace nutrients, with potential ecological constraints on emerging eukaryotic life. Here, we exploit the differing redox behavior of molybdenum and chromium to provide constraints on seafloor redox evolution by coupling a large database of sedimentary metal enrichments to a mass balance model that includes spatially variant metal burial rates. We find that the metal enrichment record implies a Proterozoic deep ocean characterized by pervasive anoxia relative to the Phanerozoic (at least ∼30-40% of modern seafloor area) but a relatively small extent of euxinic (anoxic and sulfidic) seafloor (less than ∼1-10% of modern seafloor area). Our model suggests that the oceanic Mo reservoir is extremely sensitive to perturbations in the extent of sulfidic seafloor and that the record of Mo and chromium enrichments through time is consistent with the possibility of a Mo-N colimited marine biosphere during many periods of Earth's history.

  8. Optimal Inventory Policy Involving Ordering Cost Reduction, Back-Order Discounts, and Variable Lead Time Demand by Minimax Criterion

    Directory of Open Access Journals (Sweden)

    Jong-Wuu Wu

    2009-01-01

    Full Text Available This paper allows the backorder rate as a control variable to widen applications of a continuous review inventory model. Moreover, we also consider the backorder rate that is proposed by combining Ouyang and Chuang (2001 (or Lee (2005 with Pan and Hsiao (2001 to present a new form. Thus, the backorder rate is dependent on the amount of shortages and backorder price discounts. Besides, we also treat the ordering cost as a decision variable. Hence, we develop an algorithmic procedure to find the optimal inventory policy by minimax criterion. Finally, a numerical example is also given to illustrate the results.

  9. Efficient Scheduling of Scientific Workflows with Energy Reduction Using Novel Discrete Particle Swarm Optimization and Dynamic Voltage Scaling for Computational Grids

    Directory of Open Access Journals (Sweden)

    M. Christobel

    2015-01-01

    Full Text Available One of the most significant and the topmost parameters in the real world computing environment is energy. Minimizing energy imposes benefits like reduction in power consumption, decrease in cooling rates of the computing processors, provision of a green environment, and so forth. In fact, computation time and energy are directly proportional to each other and the minimization of computation time may yield a cost effective energy consumption. Proficient scheduling of Bag-of-Tasks in the grid environment ravages in minimum computation time. In this paper, a novel discrete particle swarm optimization (DPSO algorithm based on the particle’s best position (pbDPSO and global best position (gbDPSO is adopted to find the global optimal solution for higher dimensions. This novel DPSO yields better schedule with minimum computation time compared to Earliest Deadline First (EDF and First Come First Serve (FCFS algorithms which comparably reduces energy. Other scheduling parameters, such as job completion ratio and lateness, are also calculated and compared with EDF and FCFS. An energy improvement of up to 28% was obtained when Makespan Conservative Energy Reduction (MCER and Dynamic Voltage Scaling (DVS were used in the proposed DPSO algorithm.

  10. Aerosol exposure versus aerosol cooling of climate: what is the optimal emission reduction strategy for human health?

    Directory of Open Access Journals (Sweden)

    J. Löndahl

    2010-10-01

    Full Text Available Particles, climate change, and health have thought-provoking interactions. Air pollution is one of the largest environmental problems concerning human health. On the other hand, aerosol particles can have a cooling effect on climate and a reduction of those emissions may result in an increased temperature globally, which in turn may have negative health effects. The objective of this work was to investigate the "total health effects" of aerosol emissions, which include both exposure to particles and consequences for climate change initiated by particles. As a case study the "total health effect" from ship emissions was derived by subtracting the number of deaths caused by exposure with the estimated number of lives saved from the cooling effect of the emissions. The analysis showed that, with current level of scientific understanding, it could not be determined whether ship emissions are negative or positive for human health on a short time scale. This first attempt to approximate the combined effect of particle emissions on health shows that reductions of particulate air pollution will in some cases (black carbon have win-win effects on health and climate, but sometimes also cause a shift from particle exposure-related health effects towards an increasing risk of health consequences from climate change. Thus, measures to reduce aerosol emissions have to be coupled with climate change mitigation actions to achieve a full health benefit on a global level.

  11. Optimization of total harmonic current distortion and torque pulsation reduction in high-power induction motors using genetic algorithms

    Institute of Scientific and Technical Information of China (English)

    Arash SAYYAH; Mitra AFLAK; Alireza REZAZADEH

    2008-01-01

    This paper presents a powerful application of genetic algorithm (GA) for the minimization of the total harmonic current distortion (THCD) in high-power induction motors fed by voltage source inverters,based on an approximate harmonic model. That is,having defined a desired fundamental output voltage,optimal pulse patterns (switching angles) are determined to produce the fundamental output voltage while minimizing the THCD. The complete results for the two cases of three and five switching instants in the first quarter period of pulse width modulation (PWM) waveform are presented. Presence of harmonics in the stator excitation leads to a pulsing-torque component. Considering the fact that if the pulsing-torques are at low frequencies,they can cause troublesome speed fluctuations,shaft fatigue,and unsatisfactory performance in the feedback control system,the 5th,7th,11 th,and 13th current harmonics (in the case of five switching angles) are con strained at some pre-specified values,to mitigate the detrimental effects of low-frequency harmonics. At the same time,the THCD is optimized while the required fun-damental output voltage is maintained.

  12. Hydrologic and Biogeochemical Controls on Hyporheic N2O Emissions

    Science.gov (United States)

    Quick, A. M.; Reeder, W. J.; Farrell, T. B.; Tonina, D.; Feris, K. P.; Benner, S. G.

    2016-12-01

    The hyporheic zones (HZ) of streams and rivers may be a significant source of nitrous oxide (N2O) emissions, but the hydrological and biogeochemical controls on if and how much N2O is released from the HZ are not well constrained. We employed a multidisciplinary approach to examine HZ N2O emissions that included a column experiment and two large-scale flume experiments in which we controlled initial particulate organic matter, exogenous nitrate loading, flow rates, and streambed geomorphology at the scales of a natural stream. In both 1D (column) and 2D (flume) experiments, hyporheic flow paths and residence times were modeled and measured with tracers. We measured in-situ pore water concentrations of dissolved oxygen and inorganic nitrogen species, including dissolved N2O. We observed both N2O production and consumption along HZ flow paths. Our results indicate that N2O generation and consumption are dictated by hyporheic residence times and biological nitrogen reduction rates. For N2O to be released from the HZ, residence times must be sufficiently long (or reaction rates must be sufficiently fast) to promote reduction of nitrate to N2O. However, if residence times are too long (or reaction rates are too fast) N2O will be converted to N2. As a result, only a small fraction of HZ flow paths will produce N2O at a given time. For example, although we observed concentrations up to 122 μg L-1 N-N2O in the HZ, most of this N2O was reduced to N2 before leaving the HZ and entering the surface stream water. We also observed that higher N2O concentrations in the HZ correspond to high surface water nitrate and low carbon reactivity in the sediments. The conceptual model supported by these flume and column experiments suggests that both reduction of nitrate loading and increased hyporheic residence times may moderate the potential for N2O emissions from stream hyporheic zones.

  13. Application of multilevel reduction algorithm to PCB path optimization%多级规约算法在PCB钻孔路径优化中的应用

    Institute of Scientific and Technical Information of China (English)

    程森林; 曾伟

    2012-01-01

    The PCB(Printed Circuit Board) path optimization is a large-scale TSP(Traveling Salesman Problem) problem. An Enhanced Multilevel Reduction algorithm (EMR) is proposed to solve this problem. The proposed algorithm redesigns the reduction operator and brings a control parameter to improve its flexibility. Meanwhile, in view of the difficulties of saving the results produced by reduction operator, a new data structure like human family tree is presented. Experimental results, compared with the other method, demonstrate that EMR outperforms in practicability and generality with higher quality and efficiency of optimization.%以求解PCB(Printed Circuit Board)钻孔路径优化这一大规模复杂的TSP(Traveling Salesman Problem)问题为背景,研究了一种改进的多级规约算法(EMR).该算法依据工程应用中实用性、通用性的特点重新设计了多级规约算法(MR)的规约和细化算子并增加了控制参数以提高算法的灵活性;针对算法中会产生大量部分解集且难以储存这一问题,设计了一种类似人类族谱的数据结构.实验结果以及与循环LK算法和蚁群算法的对比分析表明,EMR算法兼顾了实用性和通用性,且有较高的优化质量和优化效率.

  14. 粗糙集约简的WNN隐层节点优化方法%Optimization method for hidden layer nodes of WNN based on rough set reduction

    Institute of Scientific and Technical Information of China (English)

    孟月波; 邹建华; 刘光辉; 甘旭升

    2014-01-01

    Under the premise of ensuring network performance, the key of wavelet neural network(WNN) application and promotion is how to get the most simple network structure by determining the optimal hidden layer nodes. Therefore, a Chi-Square discretization algorithm based on the information entropy and heuristic attribute reduction recursive algorithm is proposed, reduction process of the rough set theory is used to optimize wavelet neural network hidden layer nodes without changing network performance, and an aircraft aerodynamic model is built by modifying wavelet neural network. Simulation results show that WNN optimized by the proposed improved rough set method the can not only simplify the network structure, but also improve model accuracy and training speed.%在确保网络性能的前提下,如何确定最佳隐层节点,获得最简网络结构是小波神经网络(WNN)应用推广的关键。对此,引入粗糙集理论,提出了基于信息熵的卡方离散化算法和启发式的属性约简递归算法,利用粗糙集约简过程对WNN隐层节点进行精简,并将其应用于飞行器气动力建模。仿真结果表明,采用改进的粗糙集方法设计WNN,不仅能够简化网络结构,而且与未经结构优化的WNN相比,其模型精度和训练速度都得到了实质性改善。

  15. Q345B厚板坯连铸轻压下工艺的优化%Optimization of Soft Reduction Process for Q345B Thick Slab

    Institute of Scientific and Technical Information of China (English)

    马建超; 桂仲林; 苏笃星; 夏奇; 夏翁伟; 王志福

    2012-01-01

    Center separation defect of Q345B thick plates was investigated.The results show that the heavy center porosity carried over from continuous cast 320 mm thick mother slabs is the key reason for center separation defect.Analysis on soft reduction for the slabs indicates that the actual crater end is further down the strand than the calculated position from previous online solidification model,and hence,the reduction ratio is insufficient at the final stage of solidification to compensate the final solidification shrinkage.Based on the investigation and analysis,the soft reduction scheme is optimized by extending soft reduction range and increasing the reduction ratio at the final solidification stage.After the optimization,center porosity and center segregation in the slabs are alleviated,and the center separation defect in the thick Q345B plates is resolved.%针对生产中出现的厚规格Q345B板材厚度中心分层缺陷进行了调查分析,结果表明:板材中心分层是由于连铸坯中较为严重的中心疏松在后期轧制过程中未能轧合所致。进一步对Q345B连铸坯轻压下工艺调查发现,实际凝固终点位置比模型计算值靠后,且凝固末端扇形段压下率低,不足以补偿其凝固收缩,从而形成较为严重的中心疏松缺陷。在调查分析基础上,通过将该规格连铸坯轻压下区间后延并加大轻压下量,增加了凝固末端压下率,降低了连铸坯中心疏松和中心偏析程度,从而彻底解决了板材中心分层问题。

  16. Development of Optimal Catalyst Designs and Operating Strategies for Lean NOx Reduction in Coupled LNT-SCR Systems

    Energy Technology Data Exchange (ETDEWEB)

    Harold, Michael; Crocker, Mark; Balakotaiah, Vemuri; Luss, Dan; Choi, Jae-Soon; Dearth, Mark; McCabe, Bob; Theis, Joe

    2013-09-30

    Oxides of nitrogen in the form of nitric oxide (NO) and nitrogen dioxide (NO{sub 2}) commonly referred to as NO{sub x}, is one of the two chemical precursors that lead to ground-level ozone, a ubiquitous air pollutant in urban areas. A major source of NO{sub x} is generated by equipment and vehicles powered by diesel engines, which have a combustion exhaust that contains NO{sub x} in the presence of excess O{sub 2}. Catalytic abatement measures that are effective for gasoline-fueled engines such as the precious metal containing three-way catalytic converter (TWC) cannot be used to treat O2-laden exhaust containing NO{sub x}. Two catalytic technologies that have emerged as effective for NO{sub x} abatement are NO{sub x} storage and reduction (NSR) and selective catalytic reduction (SCR). NSR is similar to TWC but requires much larger quantities of expensive precious metals and sophisticated periodic switching operation, while SCR requires an on-board source of ammonia which serves as the chemical reductant of the NO{sub x}. The fact that NSR produces ammonia as a byproduct while SCR requires ammonia to work has led to interest in combining the two together to avoid the need for the cumbersome ammonia generation system. In this project a comprehensive study was carried out of the fundamental aspects and application feasibility of combined NSR/SCR. The project team, which included university, industry, and national lab researchers, investigated the kinetics and mechanistic features of the underlying chemistry in the lean NOx trap (LNT) wherein NSR was carried out, with particular focus on identifying the operating conditions such as temperature and catalytic properties which lead to the production of ammonia in the LNT. The performance features of SCR on both model and commercial catalysts focused on the synergy between the LNT and SCR converters in terms of utilizing the upstream-generated ammonia and alternative reductants such as propylene, representing the

  17. Structure optimization of the dispensing house in a combustion train for a thermal bake-out aluminum reduction cell

    Institute of Scientific and Technical Information of China (English)

    WU Chengbo; CHANG Baolong; ZHANG Li; ZHANG Binghuai

    2003-01-01

    The fume bake-out aluminum reduction cell is a novel technology possessing such advantages as easy control for the speed of heating-up, well-distributed temperature, and little cathode and anode oxidation. The key equipment of fume bake-out is a combustion train whose one important part is a dispensing house. This work deals with the numerical model and the flow and temperature fields of the dispensing house, which suggests that uniformity of flow and energy distribution is influenced by the position, shape and direction of the nozzle and cross dimension of dispensing house mainly, but is less influenced by entry speed The parameters of the dispensing house structure are optimised to satisfy the requirements for a combustion train in fume bakeout, and appropriate dimensions are obtained for a dispensing house structure.

  18. An optimized DSP implementation of adaptive filtering and ICA for motion artifact reduction in ambulatory ECG monitoring.

    Science.gov (United States)

    Berset, Torfinn; Geng, Di; Romero, Iñaki

    2012-01-01

    Noise from motion artifacts is currently one of the main challenges in the field of ambulatory ECG recording. To address this problem, we propose the use of two different approaches. First, an adaptive filter with electrode-skin impedance as a reference signal is described. Secondly, a multi-channel ECG algorithm based on Independent Component Analysis is introduced. Both algorithms have been designed and further optimized for real-time work embedded in a dedicated Digital Signal Processor. We show that both algorithms improve the performance of a beat detection algorithm when applied in high noise conditions. In addition, an efficient way of choosing this methods is suggested with the aim of reduce the overall total system power consumption.

  19. Optimization of reaction conditions for enzymatic viscosity reduction and hydrolysis of wheat arabinoxylan in an industrial ethanol fermentation residue

    DEFF Research Database (Denmark)

    Sørensen, H.R.; Pedersen, S.; Meyer, Anne Boye Strunge

    2006-01-01

    of enzyme-catalyzed hydrolysis of arabinoxylan, beta-glucan, and cellulose. In designed response surface experiments, the optimal enzyme reaction conditions with respect to pH and temperature of the vinasse, the vinasse supernatant (mainly soluble material), and the vinasse sediment (mainly insoluble...... substances) varied from pH 5.2-6.4 and 41-49 degrees C for arabinose release and from pH 4.9-5.3 and 42-46 degrees C for xylose release. Even though only limited hydrolysis of the arabinoxylan in the vinasse sediment fraction was obtained, the results indicated that the same enzyme activities acted...... on the arabinoxylan in the different vinasse fractions irrespective of the state of solubility of the substrate material. The levels of liberated arabinose and xylose increased with increased dry matter concentration during enzymatic hydrolysis in the vinasse and the vinasse supernatant, but at the same time...

  20. Reduction of exposure to acrylamide: achievements, potential of optimization, and problems encountered from the perspectives of a Swiss enforcement laboratory.

    Science.gov (United States)

    Grob, Koni

    2005-01-01

    The most important initiatives taken in Switzerland to reduce exposure of consumers to acrylamide are the separate sale of potatoes low in reducing sugars for roasting and frying, the optimization of the raw material and preparation of french fries, and campaigns to implement suitable preparation methods in the gastronomy and homes. Industry works on improving a range of other products. Although these measures can reduce high exposures by some 80%, they have little effect on the background exposure resulting from coffee, bread, and numerous other products for which no substantial improvement is in sight. At this stage, improvements should be achieved by supporting voluntary activity rather than legal limits. Committed and consistent risk communication is key, and the support of improvements presupposes innovative approaches.

  1. Analysis of Cumulative Dose to Implanted Pacemaker According to Various IMRT Delivery Methods: Optimal Dose Delivery Versus Dose Reduction Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Woo; Hong, Se Mie [Dept. of Radiation Oncology, Konkuk University Medical Center, Seoul (Korea, Republic of)

    2011-11-15

    Cancer patients with implanted cardiac pacemaker occasionally require radiotherapy. Pacemaker may be damaged or malfunction during radiotherapy due to ionizing radiation or electromagnetic interference. Although radiotherapy should be planned to keep the dose to pacemaker as low as possible not to malfunction ideally, current radiation treatment planning (RTP) system does not accurately calculate deposited dose to adjacent field border or area beyond irradiated fields. In terms of beam delivery techniques using multiple intensity modulated fields, dosimetric effect of scattered radiation in high energy photon beams is required to be detailed analyzed based on measurement data. The aim of this study is to evaluate dose discrepancies of pacemaker in a RTP system as compared to measured doses. We also designed dose reduction strategy limited value of 2 Gy for radiation treatment patients with cardiac implanted pacemaker. Total accumulated dose of 145 cGy based on in-vivo dosimetry was satisfied with the recommendation criteria to prevent malfunction of pacemaker in SS technique. However, the 2 mm lead shielder enabled the scattered doses to reduce up to 60% and 40% in the patient and the phantom, respectively. The SS technique with the lead shielding could reduce the accumulated scattered doses less than 100 cGy. Calculated and measured doses were not greatly affected by the beam delivery techniques. In-vivo and measured doses on pacemaker position showed critical dose discrepancies reaching up to 4 times as compared to planned doses in RTP. The current SS technique could deliver lower scattered doses than recommendation criteria, but use of 2 mm lead shielder contributed to reduce scattered doses by 60%. The tertiary lead shielder can be useful to prevent malfunction or electrical damage of implanted pacemakers during radiotherapy. It is required to estimate more accurate scattered doses of the patient or medical device in RTP to design proper dose reduction strategy.

  2. Facile reduction and stabilization of ginsenoside-functionalized gold nanoparticles: optimization, characterization, and in vitro cytotoxicity studies

    Science.gov (United States)

    Hurh, Joon; Markus, Josua; Kim, Yeon-Ju; Ahn, Sungeun; Castro-Aceituno, Veronica; Mathiyalagan, Ramya; Kim, Yu Jin; Yang, Deok Chun

    2017-09-01

    Gold nanoparticles (GNPs) are forecasted to provide an attractive platform in biomedicine and catalysis with their potentials of combining a variety of biophysicochemical properties into an integrated nanodevice with great therapeutic and optical functions. There are several reports of crude plant extracts mediating the conversion of metal ions into nanoparticles. However, we aimed to investigate the capability of single bioactive compounds, namely ginsenosides compound K (C-K) and Rh2, to accommodate a synergistic chemical reduction of gold salts by one-pot green chemistry. Ginsenosides C-K and Rh2 are unique triterpenoid saponins present in Panax ginseng Meyer, a perennial plant traditionally used as an oriental medicinal herbal with long history. C-K and Rh2 have demonstrated diverse pharmacological properties such as anticancer, anti-inflammation, anti-aging, and neuroprotective properties. The reduction of gold ions by these ginsenosides led to the production of nontoxic GNPs as tested in mouse macrophage (J774A.1) and human kidney epithelial (HEK-293) in vitro. The kinetics of the bioreduction and the influence of pH were examined by an ultraviolet-visible (UV-Vis) spectrophotometer. GNPs were characterized by field emission transmission electron microscopy (FE-TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and Fourier transform infrared (FTIR) spectroscopy. Ginsenoside loading efficiency of C-K-GNPs and Rh2-GNPs was determined to be approximately 62.83% and 54.91%, respectively, by thermogravimetric analysis (TGA). These results suggest that one-pot synthesis by ginsenosides C-K and Rh2 may be useful for producing ginsenoside-loaded gold nanocarriers. [Figure not available: see fulltext.

  3. A generic biogeochemical module for earth system models

    Directory of Open Access Journals (Sweden)

    Y. Fang

    2013-06-01

    Full Text Available Physical and biogeochemical processes regulate soil carbon dynamics and CO2 flux to and from the atmosphere, influencing global climate changes. Integration of these processes into earth system models (e.g. community land models – CLM, however, currently faces three major challenges: (1 extensive efforts are required to modify modeling structures and to rewrite computer programs to incorporate new or updated processes as new knowledge is being generated, (2 computational cost is prohibitively expensive to simulate biogeochemical processes in land models due to large variations in the rates of biogeochemical processes, and (3 various mathematical representations of biogeochemical processes exist to incorporate different aspects of fundamental mechanisms, but systematic evaluation of the different mathematical representations is difficult, if not impossible. To address these challenges, we propose a new computational framework to easily incorporate physical and biogeochemical processes into land models. The new framework consists of a new biogeochemical module with a generic algorithm and reaction database so that new and updated processes can be incorporated into land models without the need to manually set up the ordinary differential equations to be solved numerically. The reaction database consists of processes of nutrient flow through the terrestrial ecosystems in plants, litter and soil. This framework facilitates effective comparison studies of biogeochemical cycles in an ecosystem using different conceptual models under the same land modeling framework. The approach was first implemented in CLM and benchmarked against simulations from the original CLM-CN code. A case study was then provided to demonstrate the advantages of using the new approach to incorporate a phosphorus cycle into the CLM model. To our knowledge, the phosphorus-incorporated CLM is a new model that can be used to simulate phosphorus limitation on the productivity of

  4. Ensemble data assimilation for ocean biogeochemical state and parameter estimation at different sites

    Science.gov (United States)

    Gharamti, M. E.; Tjiputra, J.; Bethke, I.; Samuelsen, A.; Skjelvan, I.; Bentsen, M.; Bertino, L.

    2017-04-01

    We develop an efficient data assimilation system that aims at quantifying the uncertainties of various biogeochemical states and parameters. We explore the use of four different ensemble estimation techniques for tuning poorly constrained ecosystem parameters using a one-dimensional configuration of the Ocean Biogeochemical General Circulation Model. The schemes are all EnKF-based operating sequentially in time but have different correction equations. The 1D model is used to simulate the biogeochemical cycle at three different stations in mid and high latitudes. We assimilate monthly climatological profiles of nitrate, silicate, phosphate and oxygen in addition to seasonal surface pCO2 data, between 2006 and 2010. We use the data to optimize eleven ecosystem parameters in addition to all state variables of the model, describing the dynamical processes of the water column. Our assimilation results suggest the following: (1) Among all tested schemes, the one-step-ahead smoothing-based ensemble Kalman filter (OSA-EnKF) is robust and the most accurate, providing consistent and reliable state-parameter ensemble realizations. (2) Given the large uncertainties associated with the ecosystem parameters, estimating only the state variables is generally inconclusive and biased. (3) The OSA-EnKF successfully recovers the observed seasonal variability of the ecosystem dynamics at all stations and helps optimizing the parameters, eventually reducing the prediction errors of the nutrients' concentrations. (4) The estimates of the parameters may have some temporally correlated features and they can also vary spatially between different regions depending on the magnitude of the bias in the observed variables and other factors such as the intensity of the bloom period. We further show that the presented assimilation system has the potential to be used in global models.

  5. Ligand-optimized electroless synthesis of silver nanotubes and their activity in the reduction of 4-nitrophenol.

    Science.gov (United States)

    Muench, Falk; Rauber, Markus; Stegmann, Christian; Lauterbach, Stefan; Kunz, Ulrike; Kleebe, Hans-Joachim; Ensinger, Wolfgang

    2011-10-14

    A facile electroless plating procedure for the controlled synthesis of nanoscale silver thin films and derived structures such as silver nanotubes was developed and the products were characterized by SEM, TEM and EDS. The highly stable plating baths consist of AgNO(3) as the metal source, a suitable ligand and tartrate as an environmentally benign reducing agent. Next to the variation of the coordinative environment of the oxidizing component, the influence of the pH value was evaluated. These two governing factors strongly affect the plating rate and the morphology of the developing silver nanoparticle films and can be used to adapt the reaction to synthetic demands. The refined electroless deposition allows the fabrication of homogeneous high aspect-ratio nanotubes in ion track etched polycarbonate. Template-embedded metal nanotubes can be interpreted as parallelled microreactors. Following this concept, both the silver nanotubes and spongy gold nanotubes obtained by the use of the silver structures as sacrificial templates were applied in the reduction of 4-nitrophenol by sodium borohydride, proving to be extraordinarily effective catalysts.

  6. Shot count reduction for non-Manhattan geometries: concurrent optimization of data fracture and mask writer design

    Science.gov (United States)

    Cinque, Russell; Komagata, Tadashi; Kiuchi, Taiichi; Browning, Clyde; Schiavone, Patrick; Petroni, Paolo; Martin, Luc; Quaglio, Thomas

    2013-09-01

    VSB mask writers, which create patterns using a combination of rectangles and 45 degree triangles, are ill-suited to non- Manhattan geometries. This issue is particularly acute for layouts which contain a large fraction of curvilinear "offangle" patterns such as photonic or DRAM designs. Unable to faithfully reproduce the "off-angle" structures, traditional VSB mask writers approximate the desired design using abutted rectangular shots or small shapes to smooth out line edge roughness. Fidelity to the original pattern comes at a cost of increased shot count and reduced throughput. Aselta has developed a novel fracture algorithm to dramatically reduce the shot count of such designs. Using a traditional VSB pattern generator, the new algorithm provides significant shot count reduction. When combined with a modified JBX-3200MV VSB, the shot count is reduced while maintaining the same level of fidelity. The data preparation software tool has also the capability of trading off a more accurate level of fidelity with an even more reduced shot count. The paper will first describe the basic principles of the fracturing algorithm and e-beam writer hardware configuration then demonstrate the advantage of the method on a variety of patterns.

  7. Arctic Ocean shelf biogeochemical cycling under climate change

    Science.gov (United States)

    Bellerby, Richard; Silyakova, Anna; Slagstad, Dag

    2014-05-01

    Changes to Arctic Ocean biogeochemistry will result from a complex array of climate and chemical perturbations over the next decades. Changes to freshwater and nutrient supply through ice melt and continental runoff; warming of the ocean and an increasing ocean acidification through partial equilibrium with a rising anthropogenic CO2 load will change the nature of Arctic Ocean ecological and biogeochemical coupling. This is no more apparent on the shelf regions where there is strong influence from land sources of freshwater and total alkalinity. This presentation will document our combined approach of studying Arctic biogeochemical change through coupled observational, experimental and modelling campaigns. We have identified large changes in recent anthropogenic carbon transport to the Arctic and have characterised the associated regional and water mass ocean acidification. We have determined, through targeted Arctic pelagic ecosystem perturbations experiments, changes to ecosystem structure, succession and biogeochemical cycling under high CO2. Observations have been incorporated into regional, coupled physical-ecosystem-carbon biogeochemical models (informed at the boundaries by downscaled global earth system models) to develop scenarios of change in biogeochemical pathways. We have identified large regional variability in ocean acidification that is shown to impact on shelf biogeochemistry, ecosystems and climate feedbacks in the Arctic Ocean.

  8. A Chloroflexi bacterium dechlorinates polychlorinated biphenyls in marine sediments under in situ-like biogeochemical conditions.

    Science.gov (United States)

    Zanaroli, Giulio; Balloi, Annalisa; Negroni, Andrea; Borruso, Luigimaria; Daffonchio, Daniele; Fava, Fabio

    2012-03-30

    We investigated the reductive dechlorination of Aroclor 1254 PCBs by a coplanar PCB-dechlorinating microbial community enriched from an actual site contaminated marine sediment of the Venice lagoon in sterile slurry microcosms of the same sediment suspended in its site water, i.e., under biogeochemical conditions that closely mime those occurring in situ. The culture dechlorinated more than 75% of the penta- through hepta-chlorinated biphenyls to tri- and tetra-chlorinated congeners in 30 weeks. The dechlorination rate was reduced by the addition of H(2) and short chain fatty acids, which stimulated sulfate-reduction and methane production, and markedly increased by the presence of vancomycin or ampicillin. DGGE analysis of 16S rRNA genes on PCB-spiked and PCB-free cultures ruled out sulfate-reducing and methanogenic bacteria and revealed the presence of a single Chloroflexi phylotype closely related to the uncultured bacteria m-1 and SF1 associated to PCB dechlorination. These findings suggest that a single dechlorinator is responsible for the observed extensive dechlorination of Aroclor 1254 and that a Chloroflexi species similar to those already detected in freshwater and estuarine contaminated sediments mediates PCB dechlorination in the marine sediment adopted in this study under biogeochemical conditions resembling those occurring in situ in the Brentella Canal of Venice Lagoon.

  9. Biogeochemical implications of the ubiquitous colonization of marine habitats and redox gradients by Marinobacter species

    Directory of Open Access Journals (Sweden)

    Kim Marie Handley

    2013-05-01

    Full Text Available The Marinobacter genus comprises widespread marine bacteria, found in localities as diverse as the deep ocean, coastal seawater and sediment, hydrothermal settings, oceanic basalt, sea-ice, sand, solar salterns, and oil fields. Terrestrial sources include saline soil and wine-barrel-decalcification wastewater. The genus was designated in 1992 for the Gram-negative, hydrocarbon-degrading bacterium Marinobacter hydrocarbonoclasticus. Since then, a further 31 type strains have been designated. Nonetheless, the metabolic range of many Marinobacter species remains largely unexplored. Most species have been classified as aerobic heterotrophs, and assessed for limited anaerobic pathways (fermentation or nitrate reduction, whereas studies of low-temperature hydrothermal sediments, basalt at oceanic spreading centers, and phytoplankton have identified species that possess a respiratory repertoire with significant biogeochemical implications. Notable physiological traits include nitrate-dependent Fe(II-oxidation, arsenic and fumarate redox cycling, and Mn(II oxidation. There is also evidence for Fe(III reduction, and metal(loid resistance. Considering the ubiquity and metabolic capabilities of the genus, Marinobacter species may perform an important and underestimated role in the biogeochemical cycling of organics and metals in varied marine habitats, and spanning aerobic-to-anoxic redox gradients.

  10. A coupled biogeochemical-Dynamic Energy Budget model as a tool for managing fish production ponds.

    Science.gov (United States)

    Serpa, Dalila; Pousão-Ferreira, Pedro; Caetano, Miguel; Cancela da Fonseca, Luís; Dinis, Maria Teresa; Duarte, Pedro

    2013-10-01

    The sustainability of semi-intensive aquaculture relies on management practices that simultaneously improve production efficiency and minimize the environmental impacts of this activity. The purpose of the present work was to develop a mathematical model that reproduced the dynamics of a semi-intensive fish earth pond, to simulate different management scenarios for optimizing fish production. The modeling approach consisted of coupling a biogeochemical model that simulated the dynamics of the elements that are more likely to affect fish production and cause undesirable environmental impacts (nitrogen, phosphorus and oxygen) to a fish growth model based on the Dynamic Energy Budget approach. The biogeochemical sub-model successfully simulated most water column and sediment variables. A good model fit was also found between predicted and observed white seabream (Diplodus sargus) growth data over a production cycle. In order to optimize fish production, different management scenarios were analysed with the model (e.g. increase stocking densities, decrease/increase water exchange rates, decrease/increase feeding rates, decrease phosphorus content in fish feeds, increase food assimilation efficiency and decrease pellets sinking velocity) to test their effects on the pond environment as well as on fish yields and effluent nutrient discharges. Scenarios were quantitatively evaluated and compared using the Analytical Hierarchical Process (AHP) methodology. The best management options that allow the maximization of fish production while maintaining a good pond environment and minimum impacts on the adjacent coastal system were to double standard stocking densities and to improve food assimilation efficiency.

  11. Optimization of Parameters in 16-slice CT-‌‌scan Protocols for Reduction of the Absorbed Dose

    Directory of Open Access Journals (Sweden)

    Shahrokh Naseri

    2014-08-01

    Full Text Available Introduction In computed tomography (CT technology, an optimal radiation dose can be achieved via changing radiation parameters such as mA, pitch factor, rotation time and tube voltage (kVp for diagnostic images. Materials and Methods In this study, the brain, abdomen, and thorax scaning was performed using Toshiba 16-slice scannerand standard AAPM and CTDI phantoms. AAPM phantom was used for the measurement of image-related parameters and CTDI phantom was utilized for the calculation of absorbed dose to patients. Imaging parameters including mA (50-400 mA, pitch factor (1 and 1.5 and rotation time (range of 0.5, 0.75, 1, 1.5 and 2 seconds were considered as independent variables. The brain, abdomen and chest imaging was performed multi-slice and spiral modes. Changes in image quality parameters including contrast resolution (CR and spatial resolution (SR in each condition were measured and determined by MATLAB software. Results After normalizing data by plotting the full width at half maximum (FWHM of point spread function (PSF in each condition, it was observed that image quality was not noticeably affected by each cases. Therefore, in brain scan, the lowest patient dose was in 150 mA and rotation time of 1.5 seconds. Based on results of scanning of the abdomen and chest, the lowest patient dose was obtained by 100 mA and pitch factors of 1 and 1.5. Conclusion It was found that images with acceptable quality and reliable detection ability could be obtained using smaller doses of radiation, compared to protocols commonly used by operators.

  12. Aquifer/aquitard interfaces: mixing zones that enhance biogeochemical reactions

    Science.gov (United States)

    McMahon, P. B.

    2001-01-01

    Several important biogeochemical reactions are known to occur near the interface between aquifer and aquitard sediments. These reactions include O2 reduction; denitrification; and Fe3+, SO42-, and CO2 (methanogenesis) reduction. In some settings, these reactions occur on the aquitard side of the interface as electron acceptors move from the aquifer into the electron-donor-enriched aquitard. In other settings, these reactions occur on the aquifer side of the interface as electron donors move from the aquitard into the electron-acceptor-enriched, or microorganism-enriched, aquifer. Thus, the aquifer/aquitard interface represents a mixing zone capable of supporting greater microbial activity than either hydrogeologic unit alone. The extent to which biogeochemical reactions proceed in the mixing zone and the width of the mixing zone depend on several factors, including the abundance and solubility of electron acceptors and donors on either side of the interface and the rate at which electron acceptors and donors react and move across the interface. Biogeochemical reactions near the aquifer/aquitard interface can have a substantial influence on the chemistry of water in aquifers and on the chemistry of sediments near the interface. Résumé. Il se produit au voisinage de l'interface entre les aquifères et les imperméables plusieurs réactions biogéochimiques importantes. Il s'agit des réactions de réduction de l'oxygène, de la dénitrification et de la réduction de Fe3+, SO42- et CO2 (méthanogenèse). Dans certaines situations, ces réactions se produisent du côté imperméable de l'interface, avec des accepteurs d'électrons qui vont de l'aquifère vers l'imperméable riche en donneurs d'électrons. Dans d'autres situations, ces réactions se produisent du côté aquifère de l'interface, avec des donneurs d'électrons qui se déplacent de l'imperméable vers l'aquifère riche en accepteurs d'électrons ou en microorganismes. Ainsi, l'interface aquif

  13. An optimal policy for a single-vendor and a single-buyer integrated system with setup cost reduction and process-quality improvement

    Science.gov (United States)

    Shu, Hui; Zhou, Xideng

    2014-05-01

    The single-vendor single-buyer integrated production inventory system has been an object of study for a long time, but little is known about the effect of investing in reducing setup cost reduction and process-quality improvement for an integrated inventory system in which the products are sold with free minimal repair warranty. The purpose of this article is to minimise the integrated cost by optimising simultaneously the number of shipments and the shipment quantity, the setup cost, and the process quality. An efficient algorithm procedure is proposed for determining the optimal decision variables. A numerical example is presented to illustrate the results of the proposed models graphically. Sensitivity analysis of the model with respect to key parameters of the system is carried out. The paper shows that the proposed integrated model can result in significant savings in the integrated cost.

  14. Curved planar reformation and optimal path tracing (CROP) method for false positive reduction in computer-aided detection of pulmonary embolism in CTPA

    Science.gov (United States)

    Zhou, Chuan; Chan, Heang-Ping; Guo, Yanhui; Wei, Jun; Chughtai, Aamer; Hadjiiski, Lubomir M.; Sundaram, Baskaran; Patel, Smita; Kuriakose, Jean W.; Kazerooni, Ella A.

    2013-03-01

    The curved planar reformation (CPR) method re-samples the vascular structures along the vessel centerline to generate longitudinal cross-section views. The CPR technique has been commonly used in coronary CTA workstation to facilitate radiologists' visual assessment of coronary diseases, but has not yet been used for pulmonary vessel analysis in CTPA due to the complicated tree structures and the vast network of pulmonary vasculature. In this study, a new curved planar reformation and optimal path tracing (CROP) method was developed to facilitate feature extraction and false positive (FP) reduction and improve our PE detection system. PE candidates are first identified in the segmented pulmonary vessels at prescreening. Based on Dijkstra's algorithm, the optimal path (OP) is traced from the pulmonary trunk bifurcation point to each PE candidate. The traced vessel is then straightened and a reformatted volume is generated using CPR. Eleven new features that characterize the intensity, gradient, and topology are extracted from the PE candidate in the CPR volume and combined with the previously developed 9 features to form a new feature space for FP classification. With IRB approval, CTPA of 59 PE cases were retrospectively collected from our patient files (UM set) and 69 PE cases from the PIOPED II data set with access permission. 595 and 800 PEs were manually marked by experienced radiologists as reference standard for the UM and PIOPED set, respectively. At a test sensitivity of 80%, the average FP rate was improved from 18.9 to 11.9 FPs/case with the new method for the PIOPED set when the UM set was used for training. The FP rate was improved from 22.6 to 14.2 FPs/case for the UM set when the PIOPED set was used for training. The improvement in the free response receiver operating characteristic (FROC) curves was statistically significant (p<0.05) by JAFROC analysis, indicating that the new features extracted from the CROP method are useful for FP reduction.

  15. Aerosol indirect effect on biogeochemical cycles and climate.

    Science.gov (United States)

    Mahowald, Natalie

    2011-11-11

    The net effect of anthropogenic aerosols on climate is usually considered the sum of the direct radiative effect of anthropogenic aerosols, plus the indirect effect of these aerosols through aerosol-cloud interactions. However, an additional impact of aerosols on a longer time scale is their indirect effect on climate through biogeochemical feedbacks, largely due to changes in the atmospheric concentration of CO(2). Aerosols can affect land and ocean biogeochemical cycles by physical forcing or by adding nutrients and pollutants to ecosystems. The net biogeochemical effect of aerosols is estimated to be equivalent to a radiative forcing of -0.5 ± 0.4 watts per square meter, which suggests that reaching lower carbon targets will be even costlier than previously estimated.

  16. Stoichiometries of remineralisation and denitrification in global biogeochemical ocean models

    Directory of Open Access Journals (Sweden)

    A. Paulmier

    2009-05-01

    Full Text Available Since the seminal paper of Redfield (1934, constant stoichiometric elemental ratios linking biotic carbon and nutrient fluxes are often assumed in marine biogeochemistry, and especially in coupled biogeochemical circulation models, to couple the global oxygen, carbon and nutrient cycles. However, when looking in more detail, some deviations from the classical Redfield stoichiometry have been reported, in particular with respect to remineralization of organic matter changing with depth or with ambient oxygen levels. We here compare the assumptions about the stoichiometry of organic matter and its remineralization that are used explicitly and implicitly in common biogeochemical ocean models. We find that the implicit assumptions made about the hydrogen content of organic matter can lead to inconsistencies in the modeled remineralization and denitrification stoichiometries. It is suggested that future marine biogeochemical models explicitly state the chemical composition assumed for the organic matter, including its oxygen and hydrogen content.

  17. Optimization of strawberry disinfection by fogging of a mixture of peracetic acid and hydrogen peroxide based on microbial reduction, color and phytochemicals retention.

    Science.gov (United States)

    Van de Velde, Franco; Vaccari, María Celia; Piagentini, Andrea Marcela; Pirovani, María Élida

    2016-09-01

    The fogging of strawberries using a environmentally friendly sanitizer mixture of peracetic acid (5%) and hydrogen peroxide (20%) was performed in a model chamber and modeled as a function of the concentration (3.4, 20.0, 60.0, 100.0 and 116.6 µL sanitizer L(-) (1) air chamber) and the treatment time (5.7, 15.0, 37.5, 60.0 and 69.3 min). The sanitizer fogging was adequate for reducing total mesophilic microbial and yeasts and moulds counts of fruits until seven days of storage at 2℃. However, sanitizer oxidant properties adversely affected the content of total anthocyanins, total phenolics, vitamin C, and antioxidant capacity to various degrees, with some deleterious changes in the fruits color, depending on the fogging conditions. A multiple numeric response optimization was developed based on 2.0 log microbiological reduction, maximum phytochemicals and antioxidant capacity retentions, with no changes in the fruits color, being the optimal fogging conditions achieved: 10.1 µL sanitizer L(-1) air chamber and 29.6 min. The fogging of strawberries at these conditions may represent a promising postharvest treatment option for extending their shelf-life without affecting their sensory quality and bioactive properties.

  18. Extracellular Electron Transport Coupling Biogeochemical Processes Centimeters

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Fossing, Henrik; Christensen, Peter Bondo

    2010-01-01

    confirmed the depth range of the electric communication and indicated donation of electrons directly from organotrophic bacteria. The separation of oxidation and reduction processes created steep pH gradients eventually causing carbonate precipitation at the surface. The results indicate that electron...... of the oxygen uptake in laboratory incubations of initially homogenized and stabilized sediment. Using microsensors and process rate measurements we further investigated the effect of the electric currents on sediment biogeochemistry. Dissolved sulfide readily donated electrons to the networks and could...

  19. Optimized method for atmospheric signal reduction in irregular sampled InSAR time series assisted by external atmospheric information

    Science.gov (United States)

    Gong, W.; Meyer, F. J.

    2013-12-01

    It is well known that spatio-temporal the tropospheric phase signatures complicate the interpretation and detection of smaller magnitude deformation signals or unstudied motion fields. Several advanced time-series InSAR techniques were developed in the last decade that make assumptions about the stochastic properties of the signal components in interferometric phases to reduce atmospheric delay effects on surface deformation estimates. However, their need for large datasets to successfully separate the different phase contributions limits their performance if data is scarce and irregularly sampled. Limited SAR data coverage is true for many areas affected by geophysical deformation. This is either due to their low priority in mission programming, unfavorable ground coverage condition, or turbulent seasonal weather effects. In this paper, we present new adaptive atmospheric phase filtering algorithms that are specifically designed to reconstruct surface deformation signals from atmosphere-affected and irregularly sampled InSAR time series. The filters take advantage of auxiliary atmospheric delay information that is extracted from various sources, e.g. atmospheric weather models. They are embedded into a model-free Persistent Scatterer Interferometry (PSI) approach that was selected to accommodate non-linear deformation patterns that are often observed near volcanoes and earthquake zones. Two types of adaptive phase filters were developed that operate in the time dimension and separate atmosphere from deformation based on their different temporal correlation properties. Both filter types use the fact that atmospheric models can reliably predict the spatial statistics and signal power of atmospheric phase delay fields in order to automatically optimize the filter's shape parameters. In essence, both filter types will attempt to maximize the linear correlation between a-priori and the extracted atmospheric phase information. Topography-related phase components, orbit

  20. Biogeochemical Cycles of Carbon and Sulfur on Early Earth (and on Mars?)

    Science.gov (United States)

    DesMarais, D. J.

    2004-01-01

    The physical and chemical interactions between the atmosphere, hydrosphere, geosphere and biosphere can be examined for elements such as carbon (C) and sulfur (S) that have played central roles for both life and the environment. The compounds of C are highly important, not only as organic matter, but also as atmospheric greenhouse gases, pH buffers in seawater, oxidation-reduction buffers virtually everywhere, and key magmatic constituents affecting plutonism and volcanism. S assumes important roles as an oxidation-reduction partner with C and Fe in biological systems, as a key constituent in magmas and volcanic gases, and as a major influence upon pH in certain environments. These multiple roles of C and S interact across a network of elemental reservoirs interconnected by physical, chemical and biological processes. These networks are termed biogeochemical C and S cycles.

  1. Sulfur and Methylmercury in the Florida Everglades - the Biogeochemical Connection

    Science.gov (United States)

    Orem, W. H.; Gilmour, C. C.; Krabbenhoft, D. P.; Aiken, G.

    2011-12-01

    Methylmercury (MeHg) is a serious environmental problem in aquatic ecosystems worldwide because of its toxicity and tendency to bioaccumulate. The Everglades receives some of the highest levels of atmospheric mercury deposition and has some of the highest levels of MeHg in fish in the USA, posing a threat to pisciverous wildlife and people through fish consumption. USGS studies show that a combination of biogeochemical factors make the Everglades especially susceptible to MeHg production and bioaccumulation: (1) vast wetland area with anoxic soils supporting anaerobic microbial activity, (2) high rates of atmospheric mercury deposition, (3) high levels of dissolved organic carbon (DOC) that complexes and stabilizes mercury in solution for transport to sites of methylation, and (4) high sulfate loading in surface water that drives microbial sulfate reduction and mercury methylation. The high levels of sulfate in the Everglades represent an unnatural condition. Background sulfate levels are estimated to be water sulfate concentrations exceeding background. Highly sulfate-enriched marshes in the northern Everglades have average sulfate levels of 60 mg/L. Sulfate loading to the Everglades is principally a result of land and water management in south Florida. The highest concentrations of sulfate, averaging 60-70 mg/L, are in canal water in the Everglades Agricultural Area (EAA). Geochemical data and a preliminary sulfur mass balance for the EAA are consistent with sulfur currently used in agriculture, and sulfur released by oxidation of organic EAA soils (including legacy agricultural applications and natural sulfur) as the primary sources of sulfate enrichment to the canals and ecosystem. Sulfate loading increases microbial sulfate reduction and MeHg production in soils. The relationship between sulfate loading and MeHg production, however, is complex. Sulfate levels up to about 20-30 mg/L increase mercury methylation, but buildup of sulfide from microbial sulfate

  2. Parameter sensitivity study of the biogeochemical model in the China coastal seas

    Institute of Scientific and Technical Information of China (English)

    JI Xuanliang; LIU Guimei; GAO Shan; WANG Hui

    2015-01-01

    In order to develop a coupled basin scale model of ocean circulation and biogeochemical cycling, we present a biogeochemical model including 12 components to study the ecosystem in the China coastal seas (CCS). The formulation of phytoplankton mortality and zooplankton growth are modified according to biological characteristics of CCS.The four sensitivity biological parameters, zooplankton assimilation efficiency rate (ZooAE_N), zooplankton basal metabolism rate (ZooBM), maximum specific growth rate of zooplankton (μ20) and maximum chlorophyll to carbon ratio (Chl2C_m) are obtained in sensitivity experiments for the phytoplankton, and experiments about the parameterμ20, half-saturation for phytoplankton NO3 uptake ( KNO3 ) and remineralization rate of small detritusN (SDeRRN) are conducted. The results demonstrate that the biogeochemical model is quite sensitive to the zooplankton grazing parameter when it ranges from 0.1 to 1.2 d–1. The KNO3 and SDeRRN also play an important role in determining the nitrogen cycle within certain ranges.The sensitive interval of KNO3 is from 0.1 to 1.5 (mmol/m3)–1, and interval of SEdRRN is from 0.01 and 0.1 d–1. The observational data from September 1998 to July 2000 obtained at SEATS station are used to validate the performance of biological model after parameters optimization. The results show that the modified model has a good capacity to reveal the biological process features, and the sensitivity analysis can save computational resources greatly during the model simulation.

  3. The Amazon region: tropical deforestation, biogeochemical cycles and the climate

    NARCIS (Netherlands)

    Kabat, P.; Andreae, M.O.; Silva-Dias, M.A.; Veraart, J.A.; Brink, N.J.

    2003-01-01

    The biogeochemical cycling of carbon, water, energy, aerosols, and trace gases in the Amazon Basin, and the interactions between deforestation, rainfall and climate were all investigated in this programme as a part of an integrated cluster of inter-linked and complementary research projects. These i

  4. Applying computationally efficient schemes for biogeochemical cycles (ACES4BGC)

    Energy Technology Data Exchange (ETDEWEB)

    Vertenstein, Mariana [Univ. Corporation For Atmospheric Research, Boulder, CO (United States)

    2016-01-11

    NCAR contributed to the ACES4BGC project through software engineering work on aerosol model implementation, build system and script changes, coupler enhancements for biogeochemical tracers, improvements to the Community Land Model (CLM) code and testing infrastructure, and coordinating and integrating code changes from the various project participants.

  5. The Amazon region: tropical deforestation, biogeochemical cycles and the climate

    NARCIS (Netherlands)

    Kabat, P.; Andreae, M.O.; Silva-Dias, M.A.; Veraart, J.A.; Brink, N.J.

    2003-01-01

    The biogeochemical cycling of carbon, water, energy, aerosols, and trace gases in the Amazon Basin, and the interactions between deforestation, rainfall and climate were all investigated in this programme as a part of an integrated cluster of inter-linked and complementary research projects. These i

  6. Biogeochemical response to widespread anoxia in the past ocean

    NARCIS (Netherlands)

    Ruvalcaba Baroni, I.

    2015-01-01

    Oxygen is a key element for life on earth. Oxygen concentrations in the ocean vary greatly in space and time. These changes are regulated by various physical and biogeochemical processes, such as primary productivity, sea surface temperatures and ocean circulation. In the geological past, several pe

  7. Ecogenomics and potential biogeochemical impacts of globally abundant ocean viruses

    NARCIS (Netherlands)

    Roux, Simon; Brum, Jennifer R; Dutilh, Bas E|info:eu-repo/dai/nl/304546313; Sunagawa, Shinichi; Duhaime, Melissa B; Loy, Alexander; Poulos, Bonnie T; Solonenko, Natalie; Lara, Elena; Poulain, Julie; Pesant, Stéphane; Kandels-Lewis, Stefanie; Dimier, Céline; Picheral, Marc; Searson, Sarah; Cruaud, Corinne; Alberti, Adriana; Duarte, Carlos M; Gasol, Josep M; Vaqué, Dolors

    2016-01-01

    Ocean microbes drive biogeochemical cycling on a global scale. However, this cycling is constrained by viruses that affect community composition, metabolic activity, and evolutionary trajectories. Owing to challenges with the sampling and cultivation of viruses, genome-level viral diversity remains

  8. Water pulses and biogeochemical cycles in arid and semiarid ecosystems.

    Science.gov (United States)

    Austin, Amy T; Yahdjian, Laura; Stark, John M; Belnap, Jayne; Porporato, Amilcare; Norton, Urszula; Ravetta, Damián A; Schaeffer, Sean M

    2004-10-01

    , decoupling resource supply and microbial and plant demand, and resulting in increased losses via other pathways and reduction in overall soil nutrient pools. The asynchrony of resource availability, particularly nitrogen versus water due to pulsed water events, may be central to understanding the consequences for ecosystem nutrient retention and long-term effects on carbon and nutrient pools. Finally, global change effects due to changes in the nature and size of pulsed water events and increased asynchrony of water availability and growing season will likely have impacts on biogeochemical cycling in water-limited ecosystems.

  9. Earth's Early Biosphere and the Biogeochemical Carbon Cycle

    Science.gov (United States)

    DesMarais, David

    2004-01-01

    Our biosphere has altered the global environment principally by influencing the chemistry of those elements most important for life, e g., C, N, S, O, P and transition metals (e.g., Fe and Mn). The coupling of oxygenic photosynthesis with the burial in sediments of photosynthetic organic matter, and with the escape of H2 to space, has increased the state of oxidation of the Oceans and atmosphere. It has also created highly reduced conditions within sedimentary rocks that have also extensively affected the geochemistry of several elements. The decline of volcanism during Earth's history reduced the flow of reduced chemical species that reacted with photosynthetically produced O2. The long-term net accumulation of photosynthetic O2 via biogeochemical processes has profoundly influenced our atmosphere and biosphere, as evidenced by the O2 levels required for algae, multicellular life and certain modem aerobic bacteria to exist. When our biosphere developed photosynthesis, it tapped into an energy resource that was much larger than the energy available from oxidation-reduction reactions associated with weathering and hydrothermal activity. Today, hydrothermal sources deliver globally (0.13-1.1)x10(exp l2) mol yr(sup -1) of reduced S, Fe(2+), Mn(2+), H2 and CH4; this is estimated to sustain at most about (0.2-2)xl0(exp 12)mol C yr(sup -1) of organic carbon production by chemautotrophic microorganisms. In contrast, global photosynthetic productivity is estimated to be 9000x10(exp 12) mol C yr(sup -1). Thus, even though global thermal fluxes were greater in the distant geologic past than today, the onset of oxygenic photosynthesis probably increased global organic productivity by some two or more orders of magnitude. This enormous productivity materialized principally because oxygenic photosynthesizers unleashed a virtually unlimited supply of reduced H that forever freed life from its sole dependence upon abiotic sources of reducing power such as hydrothermal emanations

  10. Earth's Early Biosphere and the Biogeochemical Carbon Cycle

    Science.gov (United States)

    DesMarais, David

    2004-01-01

    Our biosphere has altered the global environment principally by influencing the chemistry of those elements most important for life, e g., C, N, S, O, P and transition metals (e.g., Fe and Mn). The coupling of oxygenic photosynthesis with the burial in sediments of photosynthetic organic matter, and with the escape of H2 to space, has increased the state of oxidation of the Oceans and atmosphere. It has also created highly reduced conditions within sedimentary rocks that have also extensively affected the geochemistry of several elements. The decline of volcanism during Earth's history reduced the flow of reduced chemical species that reacted with photosynthetically produced O2. The long-term net accumulation of photosynthetic O2 via biogeochemical processes has profoundly influenced our atmosphere and biosphere, as evidenced by the O2 levels required for algae, multicellular life and certain modem aerobic bacteria to exist. When our biosphere developed photosynthesis, it tapped into an energy resource that was much larger than the energy available from oxidation-reduction reactions associated with weathering and hydrothermal activity. Today, hydrothermal sources deliver globally (0.13-1.1)x10(exp l2) mol yr(sup -1) of reduced S, Fe(2+), Mn(2+), H2 and CH4; this is estimated to sustain at most about (0.2-2)xl0(exp 12)mol C yr(sup -1) of organic carbon production by chemautotrophic microorganisms. In contrast, global photosynthetic productivity is estimated to be 9000x10(exp 12) mol C yr(sup -1). Thus, even though global thermal fluxes were greater in the distant geologic past than today, the onset of oxygenic photosynthesis probably increased global organic productivity by some two or more orders of magnitude. This enormous productivity materialized principally because oxygenic photosynthesizers unleashed a virtually unlimited supply of reduced H that forever freed life from its sole dependence upon abiotic sources of reducing power such as hydrothermal emanations

  11. Biogeochemical dynamics of pollutants in Insitu groundwater remediation systems

    Science.gov (United States)

    Kumar, N.; Millot, R.; Rose, J.; Négrel, P.; Battaglia-Brunnet, F.; Diels, L.

    2010-12-01

    characterized at the end of experiment using synchrotron and other microscopic techniques (SEM, µXRF). Stable isotope signatures have been proved as a critical tool in understanding the redox and microbial processes. We monitored ∂34S, ∂66Zn and ∂56Fe isotope evolution with time to understand the relationship between biogeochemical process and isotope fractionation. We observed Δ34S biotic - abiotic ~6‰ and ∂56Fe variation up to 1.5‰ in our study. ZVI was very efficient in metal removal and also in enhancing sulfate reduction in column sediment. Arsenic reduction and thiarsenic species were also detected in biotic columns showing a positive correlation with sulfide production and Fe speciation. Latest results will be presented with integration of different processes. This multidisciplinary approach will help in deep understanding of contaminants behaviour and also to constrain the efficiency and longitivity of treatment system for different contaminants. “This is contribution of the AquaTrain MRTN (Contract No. MRTN-CT-2006-035420) funded under the European Commission sixth framework programme (2002-2006) Marie Curie Actions, Human Resources & Mobility Activity Area- Research Training Networks”

  12. Spatio-temporal evolution of biogeochemical processes at a landfill site

    Science.gov (United States)

    Arora, B.; Mohanty, B. P.; McGuire, J. T.

    2011-12-01

    Predictions of fate and transport of contaminants are strongly dependent on spatio-temporal variability of soil hydraulic and geochemical properties. This study focuses on time-series signatures of hydrological and geochemical properties at different locations within the Norman landfill site. Norman Landfill is a closed municipal landfill site with prevalent organic contamination. Monthly data at the site include specific conductance, δ18O, δ2H, dissolved organic carbon (DOC) and anions (chloride, sulfate, nitrate) from 1998-2006. Column scale data on chemical concentrations, redox gradients, and flow parameters are also available on daily and hydrological event (infiltration, drainage, etc.) scales. Since high-resolution datasets of contaminant concentrations are usually unavailable, Wavelet and Fourier analyses were used to infer the dominance of different biogeochemical processes at different spatio-temporal scales and to extract linkages between transport and reaction processes. Results indicate that time variability controls the progression of reactions affecting biodegradation of contaminants. Wavelet analysis suggests that iron-sulfide reduction reactions had high seasonal variability at the site, while fermentation processes dominated at the annual time scale. Findings also suggest the dominance of small spatial features such as layered interfaces and clay lenses in driving biogeochemical reactions at both column and landfill scales. A conceptual model that caters to increased understanding and remediating structurally heterogeneous variably-saturated media is developed from the study.

  13. Impacts of Bark Beetle Outbreaks in the Western US on Biogeochemical Cycling

    Science.gov (United States)

    Hicke, J. A.; Edburg, S. L.; Meddens, A. J.

    2011-12-01

    Insect outbreaks are major forest disturbances, altering carbon and nitrogen fluxes through growth reductions and/or tree mortality. In western North America, bark beetles have killed trees over millions of hectares. Here we report on several studies that increase our understanding of the biogeochemical impacts of bark beetle epidemics. We modified the Community Land Model to simulate these disturbances, then ran the model for a range of hypothetical, realistic outbreak conditions to explore variability in impacts. We find significant differences in the responses of carbon and nitrogen based on the severity of the outbreak, the timing of snagfall, and the time since attack. Given the importance of identifying the number of trees killed within a study region for accurately quantifying impacts, we have developed a database of mortality in the western US and British Columbia for 1997-2009. We combined this database with spatially explicit maps of carbon stocks to estimate the amount of carbon in killed trees. We also used this database to drive CLM to quantify changes in biogeochemical stocks and fluxes. We find that in some regions, bark beetle-killed trees accounted for over 30% of the carbon stocks, whereas in other areas, the number of killed trees was low. Effects on net carbon fluxes in outbreak regions were significant, with fluxes switching from sinks to sources.

  14. Biogeochemical gradients and microbial communities in Winogradsky columns established with polluted wetland sediments.

    Science.gov (United States)

    Babcsányi, Izabella; Meite, Fatima; Imfeld, Gwenaël

    2017-08-01

    A Winogradsky column is a miniature ecosystem established with enriched sediments that can be used to study the relationship between biogeochemical gradients, microbial diversity and pollutant transformation. Biogeochemical processes and microbial communities changed with time and depth in Winogradsky columns incubated with heavy-metal-polluted wetland sediments for 520 days. 16S rRNA surveys were complemented by geochemical analyses, including heavy metal proportioning, to evaluate gradients in the mostly anoxic columns. Oxygen was depleted below the water-sediment interface (WSI), while NH4+, Fe2+, S2- and acetate increased by one order of magnitude at the bottom. Microbial niche differentiation occurred mainly by depth and from the light-exposed surface to the interior of the columns. Chemical gradients resulting from nutrient uptake by algae, and from iron and sulphate reduction mainly drove diversification. Heavy-metal proportioning did not significantly influence microbial diversity as Cu and Zn were immobilised at all depths. Proteobacteria were abundant in the top water and the WSI layers, whereas Firmicutes and Bacteroida dominated down-core. Together with low diversity and richness of communities at the WSI and column bottom, changes in the bacterial community coincided with algal-derived carbon sources and cellulose fermentation, respectively. We expect this study to be the starting point for the use Winogradsky columns to study microbial and geochemical dynamics in polluted sediments. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Integrating turbulent flow, biogeochemical, and poromechanical processes in rippled coastal sediment (Invited)

    Science.gov (United States)

    Cardenas, M. B.; Cook, P. L.; Jiang, H.; Traykovski, P.

    2010-12-01

    Coastal sediments are the locus of multiple coupled processes. Turbulent flow associated with waves and currents induces porewater flow through sediment leading to fluid exchange with the water column. This porewater flow is determined by the hydraulic and elastic properties of the sediment. Porewater flow also ultimately controls biogeochemical reactions in the sediment whose rates depend on delivery of reactants and export of products. We present results from numerical modeling studies directed at integrating these processes with the goal of shedding light on these complex environments. We show how denitrification rates inside ripples are largest at intermediate permeability which represents the optimal balance of reactant delivery and anoxic conditions. It is clear that nutrient cycling and distribution within the sediment is strongly dependent on the character of the multidimensional flow field inside of sediment. More recent studies illustrate the importance of the elastic properties of the saturated sediment on modulating fluid exchange between the water column and the sediment when pressure fluctuations along the sediment-water interface occur at the millisecond scale. Pressure fluctuations occur at this temporal scale due to turbulence and associated shedding of vortices due to the ripple geometry. This suggests that biogeochemical cycling may also be affected by these high-frequency elastic effects. Future studies should be directed towards this and should take advantage of modeling tools such as those we present.

  16. Shanghai Composite Index Forecasting Based on Optimized GA Attribute Reduction%基于优化GA属性约简的上证指数预测

    Institute of Scientific and Technical Information of China (English)

    严晓明

    2011-01-01

    结合粗糙集的相关理论,优化了GA属性约简方法,针对上证指数预测的具体问题,对遗传算法的初始种群和适应度函数进行改进,将上证指数10年间数据的58个属性构成的训练集进行属性约简,并应用参数优化后的SVM分别以属性约简前后的数据集对开盘指数进行回归预测.仿真结果表明,用该算法进行属性约简后,原始数据集中冗余属性对预测结果的影响下降,预测精度提高,建模时间也相应的减少,得到了较好的结果.%An optimized genetic algorithm tor attribute conduction which was based on rough set theories was proposed. Initial population and fitness function of the genetic algorithm were improved according to situation of Shanghai Composite Index forecasting. It performs application of attribute reduction with training set which retrieve 58 attributes data from Shanghai Composite Index in recent ten years. Then, it conducts regression prediction by using parameters optimized SVM to predict stock index on the original dataset and the simplified dataset. Emulation experiment results show that it has better predict precision and time consuming performance by using simplified dataset.

  17. Dose reduction to the pediatric and adult as a result of spectral optimization for high-contrast abdominal CT: A phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Pih Hyun; Lee, Chang Lae; Kim, Dae Hong; Kim, Hee Joung [Dept. of Radiological Science and Research Institute of Health Science, Yonsei University (Korea, Republic of)

    2012-04-15

    Improvement in multi-detector row CT (MDCT) technology now allows numerous acquisitions to be easily and rapidly performed, leading to a possibly marked increase of the dose to patients. Managing patient dose is therefore a major concern in pediatric MDCT. Dose optimization consists of obtaining the lowest acceptable image quality compatible with diagnostic purposes. It is still the radiologist's responsibility to set the appropriate CT parameters (i.e., tube potential, beam collimation, tube current-time product or AEC-quality indices) to keep the dose 'as low as reasonably achievable' for diagnostic purposes. However, while radiation dose may be precisely defined by dedicated quantities such as the CT dose index (CTDI), image quality is still difficult to objectively assess. Up until now, the 'appropriate' quality ratio was mostly defined on the basis of empirical methods. The purpose of the present study was to assess and compare various physically measurable image quality indices obtained with dedicated pediatric phantoms and CT protocols in order to more clearly understand which index should preferably be used in children to manage the dose for routine abdominal MDCT protocols, and to provide guidance on dose reduction on the basis of patient dimensions.

  18. The genetic potential for key biogeochemical processes in Arctic frost flowers and young sea ice revealed by metagenomic analysis.

    Science.gov (United States)

    Bowman, Jeff S; Berthiaume, Chris T; Armbrust, E Virginia; Deming, Jody W

    2014-08-01

    Newly formed sea ice is a vast and biogeochemically active environment. Recently, we reported an unusual microbial community dominated by members of the Rhizobiales in frost flowers at the surface of Arctic young sea ice based on the presence of 16S gene sequences related to these strains. Here, we use metagenomic analysis of two samples, from a field of frost flowers and the underlying young sea ice, to explore the metabolic potential of this surface ice community. The analysis links genes for key biogeochemical processes to the Rhizobiales, including dimethylsulfide uptake, betaine glycine turnover, and halocarbon production. Nodulation and nitrogen fixation genes characteristic of terrestrial root-nodulating Rhizobiales were generally lacking from these metagenomes. Non-Rhizobiales clades at the ice surface had genes that would enable additional biogeochemical processes, including mercury reduction and dimethylsulfoniopropionate catabolism. Although the ultimate source of the observed microbial community is not known, considerations of the possible role of eolian deposition or transport with particles entrained during ice formation favor a suspended particle source for this microbial community.

  19. Multi-scale Characterization and Prediction of Coupled Subsurface Biogeochemical-Hydrological Processes

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Susan; Williams, Ken; Steefel, Carl; Banfield, Jill; Long, Phil; Slater, Lee; Pride, Steve; Jinsong Chen

    2006-06-01

    To advance solutions needed for remediation of DOE contaminated sites, approaches are needed that can elucidate and predict reactions associated with coupled biological, geochemical, and hydrological processes over a variety of spatial scales and in heterogeneous environments. Our previous laboratory experimental experiments, which were conducted under controlled and homogeneous conditions, suggest that geophysical methods have the potential for elucidating system transformations that often occur during remediation. Examples include tracking the onset and aggregation of precipitates associated with sulfate reduction using seismic and complex resistivity methods (Williams et al., 2005; Ntarlagiannis et al., 2005) as well as estimating the volume of evolved gas associated with denitrification using radar velocity. These exciting studies illustrated that geophysical responses correlated with biogeochemical changes, but also that multiple factors could impact the geophysical signature and thus a better understanding as well as integration tools were needed to advance the techniques to the point where they can be used to provide quantitative estimates of system transformations.

  20. Benthic exchange and biogeochemical cycling in permeable sediments.

    Science.gov (United States)

    Huettel, Markus; Berg, Peter; Kostka, Joel E

    2014-01-01

    The sandy sediments that blanket the inner shelf are situated in a zone where nutrient input from land and strong mixing produce maximum primary production and tight coupling between water column and sedimentary processes. The high permeability of the shelf sands renders them susceptible to pressure gradients generated by hydrodynamic and biological forces that modulate spatial and temporal patterns of water circulation through these sediments. The resulting dynamic three-dimensional patterns of particle and solute distribution generate a broad spectrum of biogeochemical reaction zones that facilitate effective decomposition of the pelagic and benthic primary production products. The intricate coupling between the water column and sediment makes it challenging to quantify the production and decomposition processes and the resultant fluxes in permeable shelf sands. Recent technical developments have led to insights into the high biogeochemical and biological activity of these permeable sediments and their role in the global cycles of matter.

  1. The microbial engines that drive Earth's biogeochemical cycles.

    Science.gov (United States)

    Falkowski, Paul G; Fenchel, Tom; Delong, Edward F

    2008-05-23

    Virtually all nonequilibrium electron transfers on Earth are driven by a set of nanobiological machines composed largely of multimeric protein complexes associated with a small number of prosthetic groups. These machines evolved exclusively in microbes early in our planet's history yet, despite their antiquity, are highly conserved. Hence, although there is enormous genetic diversity in nature, there remains a relatively stable set of core genes coding for the major redox reactions essential for life and biogeochemical cycles. These genes created and coevolved with biogeochemical cycles and were passed from microbe to microbe primarily by horizontal gene transfer. A major challenge in the coming decades is to understand how these machines evolved, how they work, and the processes that control their activity on both molecular and planetary scales.

  2. Biogeochemical Transformations in the History of the Ocean

    Science.gov (United States)

    Lenton, Timothy M.; Daines, Stuart J.

    2017-01-01

    The ocean has undergone several profound biogeochemical transformations in its 4-billion-year history, and these were an integral part of the coevolution of life and the planet. This review focuses on changes in ocean redox state as controlled by changes in biological activity, nutrient concentrations, and atmospheric O2. Motivated by disparate interpretations of available geochemical data, we aim to show how quantitative modeling—spanning microbial mats, shelf seas, and the open ocean—can help constrain past ocean biogeochemical redox states and show what caused transformations between them. We outline key controls on ocean redox structure and review pertinent proxies and their interpretation. We then apply this quantitative framework to three key questions: How did the origin of oxygenic photosynthesis transform ocean biogeochemistry? How did the Great Oxidation transform ocean biogeochemistry? And how was ocean biogeochemistry transformed in the Neoproterozoic-Paleozoic?

  3. Biogeochemical Transformations in the History of the Ocean.

    Science.gov (United States)

    Lenton, Timothy M; Daines, Stuart J

    2017-01-03

    The ocean has undergone several profound biogeochemical transformations in its 4-billion-year history, and these were an integral part of the coevolution of life and the planet. This review focuses on changes in ocean redox state as controlled by changes in biological activity, nutrient concentrations, and atmospheric O2. Motivated by disparate interpretations of available geochemical data, we aim to show how quantitative modeling-spanning microbial mats, shelf seas, and the open ocean-can help constrain past ocean biogeochemical redox states and show what caused transformations between them. We outline key controls on ocean redox structure and review pertinent proxies and their interpretation. We then apply this quantitative framework to three key questions: How did the origin of oxygenic photosynthesis transform ocean biogeochemistry? How did the Great Oxidation transform ocean biogeochemistry? And how was ocean biogeochemistry transformed in the Neoproterozoic-Paleozoic?

  4. Ocean fronts drive marine fishery production and biogeochemical cycling

    Science.gov (United States)

    Woodson, C. Brock; Litvin, Steven Y.

    2015-01-01

    Long-term changes in nutrient supply and primary production reportedly foreshadow substantial declines in global marine fishery production. These declines combined with current overfishing, habitat degradation, and pollution paint a grim picture for the future of marine fisheries and ecosystems. However, current models forecasting such declines do not account for the effects of ocean fronts as biogeochemical hotspots. Here we apply a fundamental technique from fluid dynamics to an ecosystem model to show how fronts increase total ecosystem biomass, explain fishery production, cause regime shifts, and contribute significantly to global biogeochemical budgets by channeling nutrients through alternate trophic pathways. We then illustrate how ocean fronts affect fishery abundance and yield, using long-term records of anchovy–sardine regimes and salmon abundances in the California Current. These results elucidate the fundamental importance of biophysical coupling as a driver of bottom–up vs. top–down regulation and high productivity in marine ecosystems. PMID:25624488

  5. Marine and estuarine natural microbial biofilms: ecological and biogeochemical dimensions

    Directory of Open Access Journals (Sweden)

    O. Roger Anderson

    2016-08-01

    Full Text Available Marine and estuarine microbial biofilms are ubiquitously distributed worldwide and are increasingly of interest in basic and applied sciences because of their unique structural and functional features that make them remarkably different from the biota in the plankton. This is a review of some current scientific knowledge of naturally occurring microbial marine and estuarine biofilms including prokaryotic and microeukaryotic biota, but excluding research specifically on engineering and applied aspects of biofilms such as biofouling. Because the microbial communities including bacteria and protists are integral to the fundamental ecological and biogeochemical processes that support biofilm communities, particular attention is given to the structural and ecological aspects of microbial biofilm formation, succession, and maturation, as well as the dynamics of the interactions of the microbiota in biofilms. The intent is to highlight current state of scientific knowledge and possible avenues of future productive research, especially focusing on the ecological and biogeochemical dimensions.

  6. A biogeochemical framework for bioremediation of plutonium(V) in the subsurface environment.

    Science.gov (United States)

    Deo, Randhir P; Rittmann, Bruce E

    2012-07-01

    Accidental release of plutonium (Pu) from storage facilities in the subsurface environment is a concern for the safety of human beings and the environment. Given the complexity of the subsurface environment and multivalent state of Pu, we developed a quantitative biogeochemical framework for bioremediation of Pu(V)O(2) (+) in the subsurface environment. We implemented the framework in the biogeochemical model CCBATCH by expanding its chemical equilibrium for aqueous complexation of Pu and its biological sub-models for including Pu's toxicity and reduction reactions. The quantified framework reveals that most of the Pu(V) is speciated as free Pu(V)O(2) (+) ((aq)), which is a problem if the concentration of free Pu(V)O(2) (+) is ≥28 μM (the half-maximum toxicity value for bacteria able to reduce Pu(V) to Pu(III)PO(4(am))) or ≥250 μM (the full-toxicity value that takes the bioreduction rate to zero). The framework includes bioreduction of Fe(3+) to Fe(2+), which abiotically reduces Pu(V)O(2) (+) to Pu(IV) and then to Pu(III). Biotic (enzymatic) reduction of Pu(V)O(2) (+) directly to Pu(III) by Shewanella alga (S. alga) is also included in the framework. Modeling results also reveal that for formation of Pu(III)PO(4(am)), the desired immobile product, the concentration of coexisting model strong ligand-nitrilotriacetic acid (NTA)-should be less than or equal to the concentration of total Pu(III).

  7. SU-F-I-46: Optimizing Dose Reduction in Adult Head CT Protocols While Maintaining Image Quality in Postmortem Head Scans

    Energy Technology Data Exchange (ETDEWEB)

    Lipnharski, I; Carranza, C; Quails, N; Correa, N; Rajderkar, D; Bennett, J; Rill, L; Arreola, M [University of Florida, Gainesville, FL (United States)

    2016-06-15

    Purpose: To optimize adult head CT protocol by reducing dose to an appropriate level while providing CT images of diagnostic quality. Methods: Five cadavers were scanned from the skull base to the vertex using a routine adult head CT protocol (120 kVp, 270 mA, 0.75 s rotation, 0.5 mm × 32 detectors, 70.8 mGy CTDIvol) followed by seven reduced-dose protocols with varying combinations of reduced tube current, reduced rotation time, and increased detectors with CTDIvol ranging from 38.2 to 65.6 mGy. Organ doses were directly measured with 21 OSL dosimeters placed on the surface and implanted in the head by a neurosurgeon. Two neuroradiologists assessed grey-white matter differentiation, fluid space, ventricular size, midline shift, brain mass, edema, ischemia, and skull fractures on a three point scale: (1) Unacceptable, (2) Borderline Acceptable, and (3) Acceptable. Results: For the standard scan, doses to the skin, lens of the eye, salivary glands, thyroid, and brain were 37.55 mGy, 49.65 mGy, 40.67 mGy, 4.63 mGy, and 27.33 mGy, respectively. Two cadavers had cerebral edema due to changing dynamics of postmortem effects, causing the grey-white matter differentiation to appear less distinct. Two cadavers with preserved grey-white matter received acceptable scores for all image quality features for the protocol with a CTDIvol of 57.3 mGy, allowing organ dose savings ranging from 34% to 45%. One cadaver allowed for greater dose reduction for the protocol with a CTDIvol of 42 mGy. Conclusion: Efforts to optimize scan protocol should consider both dose and clinical image quality. This is made possible with postmortem subjects, whose brains are similar to patients, allowing for an investigation of ideal scan parameters. Radiologists at our institution accepted scan protocols acquired with lower scan parameters, with CTDIvol values closer to the American College of Radiology’s (ACR) Achievable Dose level of 57 mGy.

  8. What sea-ice biogeochemical modellers need from observers

    Directory of Open Access Journals (Sweden)

    Nadja Steiner

    2016-02-01

    Full Text Available Abstract Numerical models can be a powerful tool helping to understand the role biogeochemical processes play in local and global systems and how this role may be altered in a changing climate. With respect to sea-ice biogeochemical models, our knowledge is severely limited by our poor confidence in numerical model parameterisations representing those processes. Improving model parameterisations requires communication between observers and modellers to guide model development and improve the acquisition and presentation of observations. In addition to more observations, modellers need conceptual and quantitative descriptions of the processes controlling, for example: primary production and diversity of algal functional types in sea ice, ice algal growth, release from sea ice, heterotrophic remineralisation, transfer and emission of gases (e.g., DMS, CH4, BrO, incorporation of seawater components in growing sea ice (including Fe, organic and inorganic carbon, and major salts and subsequent release; CO2 dynamics (including CaCO3 precipitation, flushing and supply of nutrients to sea-ice ecosystems; and radiative transfer through sea ice. These issues can be addressed by focused observations, as well as controlled laboratory and field experiments that target specific processes. The guidelines provided here should help modellers and observers improve the integration of measurements and modelling efforts and advance toward the common goal of understanding biogeochemical processes in sea ice and their current and future impacts on environmental systems.

  9. Estimating impacts of lichens and bryophytes on global biogeochemical cycles

    Science.gov (United States)

    Porada, Philipp; Weber, Bettina; Elbert, Wolfgang; Pöschl, Ulrich; Kleidon, Axel

    2014-02-01

    Lichens and bryophytes may significantly affect global biogeochemical cycles by fixation of nitrogen and biotic enhancement of surface weathering rates. Most of the studies suggesting these effects, however, are either conceptual or rely on upscaling of regional estimates to obtain global numbers. Here we use a different method, based on estimates of net carbon uptake, to quantify the impacts of lichens and bryophytes on biogeochemical cycles at the global scale. We focus on three processes, namely, nitrogen fixation, phosphorus uptake, and chemical weathering. Our estimates have the form of potential rates, which means that we quantify the amount of nitrogen and phosphorus needed by the organisms to build up biomass, also accounting for resorption and leaching of nutrients. Subsequently, we use potential phosphorus uptake on bare ground to estimate chemical weathering by the organisms, assuming that they release weathering agents to obtain phosphorus. The predicted requirement for nitrogen ranges from 3.5 to 34 Tgyr-1 and for phosphorus it ranges from 0.46 to 4.6 Tgyr-1. Estimates of chemical weathering are between 0.058 and 1.1 km3 yr-1 of rock. These values seem to have a realistic order of magnitude, and they support the notion that lichens and bryophytes have the potential to play an important role for biogeochemical cycles.

  10. Optimization of the nitrous vapors experimental conditions production by nitric acid electrochemical reduction; Optimisation des conditions operatoires de production de vapeurs nitreuses par reduction electrochimique d`acide nitrique

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, M.

    1996-11-22

    Gaseous nitrogen oxides (NO and NO{sub 2}) involved as oxidizing agents in nuclear fuel reprocessing can be produced by electrochemical reduction of nitric acid. This is an interesting alternative to the existing process because no wastes are generated. voltammetric studies on a platinum electrode show that two reduction potential regions are observed in concentrated nitric acid solutions, between 0,05 V{sub SHE} and between 0,5 V{sub SHE} and 1 V{sub SHE}. The highest potential region reduction mechanism was studied by: classical micro-electrolysis methods, macro-electrolysis methods, infrared spectroscopy coupled to electrochemistry. It was determined that the origin of nitric acid reduction is the electrochemical reduction of nitrous acid in nitric oxide which chemically reduces nitric acid. This reaction produces nitrous acid back which indicate an auto-catalytic behaviour of nitric acid reduction mechanism. Nitrogen dioxide evolution during nitric reduction can also explained by an other chemical reaction. If the potential value of platinum electrode is above 0,8 V{sub SHE}, products of the indirect nitric acid reduction are nitrous acid, nitrogen oxide and nitrogen dioxide. Below this value nitric oxide can be reduced in nitrous oxide. Thus the potential value is the most important parameter for the nitrogen oxides production selectivity. However, owing to the auto-catalytic character of the reduction mechanism, potential value can be controlled during intentiostatic industrial electrolysis. (author). 91 refs.

  11. Plant impact on the coupled terrestrial biogeochemical cycles of silicon and carbon: Implications for biogeochemical carbon sequestration

    Science.gov (United States)

    Song, Zhaoliang; Wang, Hailong; Strong, P. James; Li, Zimin; Jiang, Peikun

    2012-12-01

    The coupled terrestrial biogeochemical cycles of silicon (Si) and carbon (C) that are driven by plant action play a crucial role in the regulation of atmospheric CO2. Generally, the processes involved in the coupled cycles of Si and C include plant-enhanced silicate weathering, phytolith formation and solubilization, secondary aluminosilicate accumulation, phytolith occlusion of C as well as physico-chemical protection of organic C in soils. There is increasing evidence of biological pumping of Si in terrestrial ecosystems, suggesting that complex feedbacks exist amongst the processes within the coupled Si and C cycles. Recent advances in the coupled Si and C cycles offer promising new possibilities for enhancing atmospheric CO2 sequestration. Organic mulching, rock powder amendment, cultivating Si-accumulating plants and partial plant harvesting are potential measures that may allow for long-term manipulation and biogeochemical sequestration of atmospheric CO2 in soil-plant systems.

  12. iFit: a new data analysis framework. Applications for data reduction and optimization of neutron scattering instrument simulations with McStas

    DEFF Research Database (Denmark)

    Farhi, E.; Y., Debab,; Willendrup, Peter Kjær

    2014-01-01

    and noisy problems. These optimizers can then be used to fit models onto data objects, and optimize McStas instrument simulations. As an application, we propose a methodology to analyse neutron scattering measurements in a pure Monte Carlo optimization procedure using McStas and iFit. As opposed...

  13. The Neoproterozoic oxygenation event: Environmental perturbations and biogeochemical cycling

    Science.gov (United States)

    Och, Lawrence M.; Shields-Zhou, Graham A.

    2012-01-01

    The oxygen content of the Earth's surface environment is thought to have increased in two broad steps: the Great Oxygenation Event (GOE) around the Archean-Proterozoic boundary and the Neoproterozoic Oxygenation Event (NOE), during which oxygen possibly accumulated to the levels required to support animal life and ventilate the deep oceans. Although the concept of the GOE is widely accepted, the NOE is less well constrained and its timing and extent remain the subjects of debate. We review available evidence for the NOE against the background of major climatic perturbations, tectonic upheaval related to the break-up of the supercontinent Rodinia and reassembly into Gondwana, and, most importantly, major biological innovations exemplified by the Ediacarian Biota and the Cambrian 'Explosion'. Geochemical lines of evidence for the NOE include perturbations to the biogeochemical cycling of carbon. Generally high δ 13C values are possibly indicative of increased organic carbon burial and the release of oxidative power to the Earth's surface environment after c. 800 Ma. A demonstrably global and primary record of extremely negative δ 13C values after about 580 Ma strongly suggests the oxidation of a large dissolved organic carbon pool (DOC), the culmination of which around c. 550 Ma coincided with an abrupt diversification of Ediacaran macrobiota. Increasing 87Sr/ 86Sr ratios toward the Neoproterozoic-Cambrian transition indicates enhanced continental weathering which may have fuelled higher organic production and burial during the later Neoproterozoic. Evidence for enhanced oxidative recycling is given by the increase in sulfur isotope fractionation between sulfide and sulfate, exceeding the range usually attained by sulfate reduction alone, reflecting an increasing importance of the oxidative part in the sulfur cycle. S/C ratios attained a maximum during the Precambrian-Cambrian transition, further indicating higher sulfate concentrations in the ocean and a

  14. The role of phytoplankton photosynthesis in global biogeochemical cycles.

    Science.gov (United States)

    Falkowski, P G

    1994-03-01

    Phytoplankton biomass in the world's oceans amounts to only ∽1-2% of the total global plant carbon, yet these organisms fix between 30 and 50 billion metric tons of carbon annually, which is about 40% of the total. On geological time scales there is profound evidence of the importance of phytoplankton photosynthesis in biogeochemical cycles. It is generally assumed that present phytoplankton productivity is in a quasi steady-state (on the time scale of decades). However, in a global context, the stability of oceanic photosynthetic processes is dependent on the physical circulation of the upper ocean and is therefore strongly influenced by the atmosphere. The net flux of atmospheric radiation is critical to determining the depth of the upper mixed layer and the vertical fluxes of nutrients. These latter two parameters are keys to determining the intensity, and spatial and temporal distributions of phytoplankton blooms. Atmospheric radiation budgets are not in steady-state. Driven largely by anthropogenic activities in the 20th century, increased levels of IR- absorbing gases such as CO2, CH4 and CFC's and NOx will potentially increase atmospheric temperatures on a global scale. The atmospheric radiation budget can affect phytoplankton photosynthesis directly and indirectly. Increased temperature differences between the continents and oceans have been implicated in higher wind stresses at the ocean margins. Increased wind speeds can lead to higher nutrient fluxes. Throughout most of the central oceans, nitrate concentrations are sub-micromolar and there is strong evidence that the quantum efficiency of Photosystem II is impaired by nutrient stress. Higher nutrient fluxes would lead to both an increase in phytoplankton biomass and higher biomass-specific rates of carbon fixation. However, in the center of the ocean gyres, increased radiative heating could reduce the vertical flux of nutrients to the euphotic zone, and hence lead to a reduction in phytoplankton

  15. A 3-D variational assimilation scheme in coupled transport-biogeochemical models: Forecast of Mediterranean biogeochemical properties.

    Science.gov (United States)

    Teruzzi, Anna; Dobricic, Srdjan; Solidoro, Cosimo; Cossarini, Gianpiero

    2014-01-01

    [1] Increasing attention is dedicated to the implementation of suitable marine forecast systems for the estimate of the state of the ocean. Within the framework of the European MyOcean infrastructure, the pre-existing short-term Mediterranean Sea biogeochemistry operational forecast system has been upgraded by assimilating remotely sensed ocean color data in the coupled transport-biogeochemical model OPATM-BFM using a 3-D variational data assimilation (3D-VAR) procedure. In the present work, the 3D-VAR scheme is used to correct the four phytoplankton functional groups included in the OPATM-BFM in the period July 2007 to September 2008. The 3D-VAR scheme decomposes the error covariance matrix using a sequence of different operators that account separately for vertical covariance, horizontal covariance, and covariance among biogeochemical variables. The assimilation solution is found in a reduced dimensional space, and the innovation for the biogeochemical variables is obtained by the sequential application of the covariance operators. Results show a general improvement in the forecast skill, providing a correction of the basin-scale bias of surface chlorophyll concentration and of the local-scale spatial and temporal dynamics of typical bloom events. Further, analysis of the assimilation skill provides insights into the functioning of the model. The computational costs of the assimilation scheme adopted are low compared to other assimilation techniques, and its modular structure facilitates further developments. The 3D-VAR scheme results especially suitable for implementation within a biogeochemistry operational forecast system.

  16. Optimization of conditions to produce nitrous gases by electrochemical reduction of nitric acid; Optimisation des conditions operatoires de production de vapeurs nitreuses par reduction electrochimique d`acide nitrique

    Energy Technology Data Exchange (ETDEWEB)

    Lemaire, M. [CEA Centre d`Etudes Nucleaires de Saclay, 91 -Gif-sur-Yvette (France)]|[CEA Centre d`Etudes de la Vallee du Rhone, 30 -Marcoule (France). Direction du Cycle du Combustible

    1996-11-22

    Gaseous nitrogen oxides (NO and NO{sub 2}) involved as oxidizing agents in nuclear fuel reprocessing can be an produced by electrochemical reduction of nitric acid. This could be an interesting alternative to the usual process because no wastes are generated. Voltammetric studies on a platinum electrode show that two reduction potential regions are observed in concentrated nitric acid solutions, between 0.05 V{sub S}HE and 0.3 V{sub S}HE and O.5 V{sub S}HE and 1 V{sub S}HE. The highest potential region reduction mechanism was studies by: classical micro-electrolysis methods; macro-electrolysis methods; infra-red spectroscopy couplet to electrochemistry. It was determined that the origin of nitric acid reduction is the electrochemical reduction of nitrous acid in nitric oxide which chemically reduces nitric acid. This reaction produces nitrous acid back which indicate an auto-catalytic behaviour of nitric acid reduction mechanism. Nitrogen dioxide evolution during nitric acid reduction can also be explained by an other chemical reaction. In the potential value of platinum electrode is above 0.8 V{sub S}HE, products of the indirect nitric acid reduction are nitrous acid, nitrogen oxide and nitrogen dioxide. Below this value nitric oxide can be reduced in nitrous oxide. Thus the potential value is the most important parameter for the nitrogen oxides production selectivity. However, owing to the auto-catalytic character of the reduction mechanism, potential value can be controlled during intentiostatic industrial electrolysis. (author). 91 refs.

  17. Monitoring Physical and Biogeochemical Dynamics of Uranium Bioremediation at the Intermediate Scale

    Science.gov (United States)

    Tarrell, A. N.; Figueroa, L. A.; Rodriguez, D.; Haas, A.; Revil, A.

    2011-12-01

    Subsurface uranium above desired levels for aquifer use categories exists naturally and from historic mining and milling practices. In situ bioimmobilization offers a cost effective alternative to conventional pump and treat methods by stimulating growth of microorganisms that lead to the reduction and precipitation of uranium. Vital to the long-term success of in situ bioimmobilization is the ability to successfully predict and demonstrate treatment effectiveness to assure that regulatory goals are met. However, successfully monitoring the progress over time is difficult and requires long-term stewardship to ensure effective treatment due to complex physical and biogeochemical heterogeneity. In order to better understand these complexities and the resultant effect on uranium immobilization, innovative systematic monitoring approaches with multiple performance indicators must be investigated. A key issue for uranium bioremediation is the long term stability of solid-phase reduction products. It has been shown that a combination of data from electrode-based monitoring, self-potential monitoring, oxidation reduction potential (ORP), and water level sensors provides insight for identifying and localizing bioremediation activity and can provide better predictions of deleterious biogeochemical change such as pore clogging. In order to test the proof-of-concept of these sensing techniques and to deconvolve redox activity from other electric potential changing events, an intermediate scale 3D tank experiment has been developed. Well-characterized materials will be packed into the tank and an artificial groundwater will flow across the tank through a constant-head boundary. The experiment will utilize these sensing methods to image the electrical current produced by bacteria as well as indications of when and where electrical activity is occurring, such as with the reduction of radionuclides. This work will expand upon current knowledge by exploring the behavior of uranium

  18. Optimization and design of an aircraft’s morphing wing-tip demonstrator for drag reduction at low speed, Part I – Aerodynamic optimization using genetic, bee colony and gradient descent algorithms

    Directory of Open Access Journals (Sweden)

    Andreea Koreanschi

    2017-02-01

    Full Text Available In this paper, an ‘in-house’ genetic algorithm is described and applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The algorithm’s performances were studied from the convergence point of view, in accordance with design conditions. The algorithm was compared to two other optimization methods, namely the artificial bee colony and a gradient method, for two optimization objectives, and the results of the optimizations with each of the three methods were plotted on response surfaces obtained with the Monte Carlo method, to show that they were situated in the global optimum region. The optimization results for 16 wind tunnel test cases and 2 objective functions were presented. The 16 cases used for the optimizations were included in the experimental test plan for the morphing wing-tip demonstrator, and the results obtained using the displacements given by the optimizations were evaluated.

  19. Abrupt shifts in ecosystem function and intensification of global biogeochemical cycle driven by hydroclimatic extremes

    Science.gov (United States)

    Ma, Xuanlong; Huete, Alfredo; Ponce-Campos, Guillermo; Zhang, Yongguang; Xie, Zunyi; Giovannini, Leandro; Cleverly, James; Eamus, Derek

    2016-04-01

    Amplification of the hydrologic cycle as a consequence of global warming is increasing the frequency, intensity, and spatial extent of extreme climate events globally. The potential influences resulting from amplification of the hydro-climatic cycle, coupled with an accelerating warming trend, pose great concerns on the sustainability of terrestrial ecosystems to sequester carbon, maintain biodiversity, provide ecosystem services, food security, and support human livelihood. Despite the great implications, the magnitude, direction, and carry-over effect of these extreme climate events on ecosystem function, remain largely uncertain. To address these pressing issues, we conducted an observational, interdisciplinary study using satellite retrievals of atmospheric CO2 and photosynthesis (chlorophyll fluorescence), and in-situ flux tower measures of ecosystem-atmosphere carbon exchange, to reveal the shifts in ecosystem function across extreme drought and wet periods. We further determine the factors that govern ecosystem sensitivity to hydroclimatic extremes. We focus on Australia but extended our analyses to other global dryland regions due to their significant role in global biogeochemical cycles. Our results revealed dramatic impacts of drought and wet hydroclimatic extremes on ecosystem function, with abrupt changes in vegetation productivity, carbon uptake, and water-use-efficiency between years. Drought resulted in widespread reductions or collapse in the normal patterns of vegetation growth seasonality such that in many cases there was no detectable phenological cycle during extreme drought years. We further identified a significant increasing trend (p global regions, resulting in an increasing trend in magnitude of the episodic carbon sink pulses coupled to each La Niña-induced wet years. This finding is of global biogeochemical significance, with the consequence of amplifying the global carbon cycle. Lastly, we use landscape measurements of carbon and water

  20. Biogeochemical mass balances in a turbid tropical reservoir. Field data and modelling approach

    Science.gov (United States)

    Phuong Doan, Thuy Kim; Némery, Julien; Gratiot, Nicolas; Schmid, Martin

    2014-05-01

    fitted well to the field measurements. Furthermore, this analysis indicates that the benthic mineralizations are the dominant processes involved in the nutrients release. This is the first implementation of a biogeochemical model applied to a highly productive reservoir in the TMVB in order to estimate nutrients release from sediments. It could be used for scenarios of reduction of eutrophication in the reservoir. This study provides a good example of the behavior of a small tropical reservoir under intense human pressure and it will help stakeholders to adopt appropriate strategies for the management of turbid tropical reservoirs.

  1. Long-term optimization of the transport sector to address greenhouse gas reduction targets under rapid growth. Application of an energy system model for Gauteng province, South Africa

    Energy Technology Data Exchange (ETDEWEB)

    Tomaschek, Jan

    2013-12-11

    The transport sector is seen as one of the key factors for driving future energy consumption and greenhouse gas (GHG) emissions. Especially in developing countries, significant growth in transport demand is expected. Gauteng province, as the economic centre of South Africa and transport hub for the whole of southern Africa, is one emerging urban region that faces rapid growth. However, the province is on its way to playing a leading role for supporting ways to adapt to climate change and mitigate GHG emissions. Conversely, there is a lack of scientific research on the promising measures for GHG mitigation in the transport sector. For the rapidly growing transport sector of the province in particular, research is focused primarily on extending and structuring the road infrastructure. Moreover, it is important that the transport sector is considered as part of the whole energy system, as significant contributions to GHG emissions and the associated costs arise from energy supply, provision and conversion. This research is the first application of an integrated energy system model (i.e. the TIMES-GEECO model) for the optimization of the transport sector of Gauteng. Optimizing energy system models allows finding least-cost measures for various scenarios, by considering dependencies and interlinkages in the energy system as well as environmental constraints. To do so, the transport sector and the energy supply sector had to be incorporated into the model application in terms of the characteristics of a developing urban region, which includes all relevant transport modes, vehicle technologies, fuel options, vehicle-to-grid energy storage, the consideration of road types as well as explicit expansions of the public transport system and income-dependent travel demand modelling. Additionally, GHG mitigation options outside the provincial boundaries were incorporated to allow for mitigation at least cost and to consider regional resource availability. Moreover, in TIMES

  2. Coarsening of physics for biogeochemical model in NEMO

    Science.gov (United States)

    Bricaud, Clement; Le Sommer, Julien; Madec, Gurvan; Deshayes, Julie; Chanut, Jerome; Perruche, Coralie

    2017-04-01

    Ocean mesoscale and submesoscale turbulence contribute to ocean tracer transport and to shaping ocean biogeochemical tracers distribution. Representing adequately tracer transport in ocean models therefore requires to increase model resolution so that the impact of ocean turbulence is adequately accounted for. But due to supercomputers power and storage limitations, global biogeochemical models are not yet run routinely at eddying resolution. Still, because the "effective resolution" of eddying ocean models is much coarser than the physical model grid resolution, tracer transport can be reconstructed to a large extent by computing tracer transport and diffusion with a model grid resolution close to the effective resolution of the physical model. This observation has motivated the implementation of a new capability in NEMO ocean model (http://www.nemo-ocean.eu/) that allows to run the physical model and the tracer transport model at different grid resolutions. In a first time, we present results obtained with this new capability applied to a synthetic age tracer in a global eddying model configuration. In this model configuration, ocean dynamic is computed at ¼° resolution but tracer transport is computed at 3/4° resolution. The solution obtained is compared to 2 reference setup ,one at ¼° resolution for both physics and passive tracer models and one at 3/4° resolution for both physics and passive tracer model. We discuss possible options for defining the vertical diffusivity coefficient for the tracer transport model based on information from the high resolution grid. We describe the impact of this choice on the distribution and one the penetration of the age tracer. In a second time we present results obtained by coupling the physics with the biogeochemical model PISCES. We look at the impact of this methodology on some tracers distribution and dynamic. The method described here can found applications in ocean forecasting, such as the Copernicus Marine

  3. Biogeochemical cycling of Si in a California rice cropping system

    Science.gov (United States)

    Seyfferth, A.; Kocar, B. D.; Lee, J.; Fendorf, S.

    2012-12-01

    Silicon is the second most abundant element in the earth's crust, but the number of studies on the biogeochemical cycling of Si does not reflect its environmental ubiquity. While not an "essential" plant nutrient, Si is important for many plants, particularly monocots, for structural integrity and protection against disease and environmental stress. For rice, Si fertilization with N and P increases yield significantly more than N and P alone. While total Si in soil is high, much of this Si is tied up in the crystal lattice of primary and secondary minerals and is only slowly released through chemical weathering. Thus, plant-available Si may be limited particularly in highly weathered soils in humid environments where long-term chemical weathering has lead to desilicification of the soils (e.g., in Southeast Asia where most rice is grown). In such Si-depleted environments, the biocycling of Si through decaying plant litter (i.e., phytoliths) and subsequent plant uptake has proven an important component of the terrestrial biogeochemical cycling of Si. Here, we investigate the dynamics of Si cycling over a two-year period in a rice paddy in Northern California where soil incorporation of harvested rice straw has impacted the terrestrial biogeochemical cycling of Si. We use Ge/Si ratios in pore-waters to infer the contribution of chemical weathering vs. dissolution of plant phytoliths on the plant-available Si pool. We found that the Ge/Si ratios change over the growing and fallow seasons reflecting different rates of Si release through phytolith dissolution and plant uptake.

  4. Ecohydrological Interfaces as Dynamic Hotspots of Biogeochemical Cycling

    Science.gov (United States)

    Krause, Stefan; Lewandowski, Joerg; Hannah, David; McDonald, Karlie; Folegot, Silvia; Baranov, Victor

    2016-04-01

    Ecohydrological interfaces, represent the boundaries between water-dependent ecosystems that can alter substantially the fluxes of energy and matter. There is still a critical gap of understanding the organisational principles of the drivers and controls of spatially and temporally variable ecohydrological interface functions. This knowledge gap limits our capacity to efficiently quantify, predict and manage the services provided by complex ecosystems. Many ecohydrological interfaces are characterized by step changes in microbial metabolic activity, steep redox gradients and often even thermodynamic phase shifts, for instance at the interfaces between atmosphere and water or soil matrix and macro-pores interfaces. This paper integrates investigations from point scale laboratory microcosm experiments with reach and subcatchment scale tracer experiments and numerical modeling studies to elaborate similarities in the drivers and controls that constitute the enhanced biogeochemical activity of different types of ecohydrologica interfaces across a range of spatial and temporal scales. We therefore combine smart metabolic activity tracers to quantify the impact of bioturbating benthic fauna onto ecosystem respiration and oxygen consumption and investigate at larger scale, how microbial metabolic activity and carbon turnover at the water-sediment interface are controlled by sediment physical and chemical properties as well as water temperatures. Numerical modeling confirmed that experimentally identified hotspots of streambed biogeochemical cycling were controlled by patterns of physical properties such as hydraulic conductivities or bioavailability of organic matter, impacting on residence time distributions and hence reaction times. In contrast to previous research, our investigations thus confirmed that small-scale variability of physical and chemical interface properties had a major impact on biogeochemical processing at the investigated ecohydrological interfaces

  5. Effects of ozone-vegetation coupling on surface ozone air quality via biogeochemical and meteorological feedbacks

    Science.gov (United States)

    Sadiq, Mehliyar; Tai, Amos P. K.; Lombardozzi, Danica; Martin, Maria Val

    2017-02-01

    Tropospheric ozone is one of the most hazardous air pollutants as it harms both human health and plant productivity. Foliage uptake of ozone via dry deposition damages photosynthesis and causes stomatal closure. These foliage changes could lead to a cascade of biogeochemical and biogeophysical effects that not only modulate the carbon cycle, regional hydrometeorology and climate, but also cause feedbacks onto surface ozone concentration itself. In this study, we implement a semi-empirical parameterization of ozone damage on vegetation in the Community Earth System Model to enable online ozone-vegetation coupling, so that for the first time ecosystem structure and ozone concentration can coevolve in fully coupled land-atmosphere simulations. With ozone-vegetation coupling, present-day surface ozone is simulated to be higher by up to 4-6 ppbv over Europe, North America and China. Reduced dry deposition velocity following ozone damage contributes to ˜ 40-100 % of those increases, constituting a significant positive biogeochemical feedback on ozone air quality. Enhanced biogenic isoprene emission is found to contribute to most of the remaining increases, and is driven mainly by higher vegetation temperature that results from lower transpiration rate. This isoprene-driven pathway represents an indirect, positive meteorological feedback. The reduction in both dry deposition and transpiration is mostly associated with reduced stomatal conductance following ozone damage, whereas the modification of photosynthesis and further changes in ecosystem productivity are found to play a smaller role in contributing to the ozone-vegetation feedbacks. Our results highlight the need to consider two-way ozone-vegetation coupling in Earth system models to derive a more complete understanding and yield more reliable future predictions of ozone air quality.

  6. Biogeochemical C and N cycles in urban soils.

    Science.gov (United States)

    Lorenz, Klaus; Lal, Rattan

    2009-01-01

    The percentage of urban population is projected to increase drastically. In 2030, 50.7 to 86.7% of the total population in Africa and Northern America may live in urban areas, respectively. The effects of the attendant increases in urban land uses on biogeochemical C and N cycles are, however, largely unknown. Biogeochemical cycles in urban ecosystems are altered directly and indirectly by human activities. Direct effects include changes in the biological, chemical and physical soil properties and processes in urban soils. Indirect effects of urban environments on biogeochemical cycles may be attributed to the introductions of exotic plant and animal species and atmospheric deposition of pollutants. Urbanization may also affect the regional and global atmospheric climate by the urban heat island and pollution island effect. On the other hand, urban soils have the potential to store large amounts of soil organic carbon (SOC) and, thus, contribute to mitigating increases in atmospheric CO(2) concentrations. However, the amount of SOC stored in urban soils is highly variable in space and time, and depends among others on soil parent material and land use. The SOC pool in 0.3-m depth may range between 16 and 232 Mg ha(-1), and between 15 and 285 Mg ha(-1) in 1-m depth. Thus, depending on the soil replaced or disturbed, urban soils may have higher or lower SOC pools, but very little is known. This review provides an overview of the biogeochemical cycling of C and N in urban soils, with a focus on the effects of urban land use and management on soil organic matter (SOM). In view of the increase in atmospheric CO(2) and reactive N concentrations as a result of urbanization, urban land use planning must also include strategies to sequester C in soil, and also enhance the N sink in urban soils and vegetation. This will strengthen soil ecological functions such as retention of nutrients, hazardous compounds and water, and also improve urban ecosystem services by promoting

  7. The global troposphere - Biogeochemical cycles, chemistry, and remote sensing

    Science.gov (United States)

    Levine, J. S.; Allario, F.

    1982-01-01

    The chemical composition of the troposphere is controlled by various biogeochemical cycles that couple the atmosphere with the oceans, the solid earth and the biosphere, and by atmospheric photochemical/chemical reactions. These cycles and reactions are discussed and a number of key questions concerning tropospheric composition and chemistry for the carbon, nitrogen, oxygen and sulfur species are identified. Next, various remote sensing techniques and instruments capable of measuring and monitoring tropospheric species from the ground, aircraft and space to address some of these key questions are reviewed. Future thrusts in remote sensing of the troposphere are also considered.

  8. Biogeochemical ocean-atmosphere transfers in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Bange, H.W.; Gibb, S.W.; Goyet, C.; Hatton, A.D.; Upstill-Goddard, R.C.

    to bring about changes in oceanic productivity, thus reg- ulating the C212powerC213 of the C212biological pumpC213 and the extent of CO 2 sequestration from the atmosphere (Altabet, Franc¸ois, Murray, & Prell, 1995; Ganeshram, Pedersen, Calvert, & Franc... sets of data are quite divergent due to differences in the methods of data interpolation and computation used. Following SCOR (1995), Ko¨rtzinger et al. (1997) divided the region into three biogeochemical provinces – Coastal Upwelling, Ekman Pumping...

  9. The global troposphere - Biogeochemical cycles, chemistry, and remote sensing

    Science.gov (United States)

    Levine, J. S.; Allario, F.

    1982-01-01

    The chemical composition of the troposphere is controlled by various biogeochemical cycles that couple the atmosphere with the oceans, the solid earth and the biosphere, and by atmospheric photochemical/chemical reactions. These cycles and reactions are discussed and a number of key questions concerning tropospheric composition and chemistry for the carbon, nitrogen, oxygen and sulfur species are identified. Next, various remote sensing techniques and instruments capable of measuring and monitoring tropospheric species from the ground, aircraft and space to address some of these key questions are reviewed. Future thrusts in remote sensing of the troposphere are also considered.

  10. Mussel farming as a nutrient reduction measure in the Baltic Sea: consideration of nutrient biogeochemical cycles.

    Science.gov (United States)

    Stadmark, J; Conley, D J

    2011-07-01

    Nutrient loads from the land to the sea must be reduced to combat coastal eutrophication. It has been suggested that further mitigation efforts are needed in the brackish Baltic Sea to decrease nutrients, especially in eutrophic coastal areas. Mussel farming is a potential measure to remove nutrients directly from the sea. Mussels consume phytoplankton containing nitrogen (N) and phosphorus (P); when the mussels are harvested these nutrients are removed from the aquatic system. However, sedimentation of organic material in faeces and pseudo-faeces below a mussel farm consumes oxygen and can lead to hypoxic or even anoxic sediments causing an increased sediment release of ammonium and phosphate. Moreover, N losses from denitrification can be reduced due to low oxygen and reduced numbers of bioturbating organisms. To reveal if mussel farming is a cost-effective mitigation measure in the Baltic Sea the potential for enhanced sediment nutrient release must be assessed.

  11. Nutrient removal using biosorption activated media: Preliminary biogeochemical assessment of an innovative stormwater infiltration basin

    Energy Technology Data Exchange (ETDEWEB)

    O' Reilly, Andrew M., E-mail: aoreilly@usgs.gov [U.S. Geological Survey, Florida Water Science Center, 12703 Research Pkwy, Orlando, FL 32826 (United States); Wanielista, Martin P., E-mail: Martin.Wanielista@ucf.edu [University of Central Florida, Water Research Center and Stormwater Management Academy, 4000 Central Florida Blvd, Building 91, Suite 442, Orlando, FL 32816 (United States); Chang, Ni-Bin, E-mail: Ni-bin.Chang@ucf.edu [University of Central Florida, Department of Civil, Environmental, and Construction Engineering, 4000 Central Florida Blvd, Building 91, Suite 442, Orlando, FL 32816 (United States); Xuan, Zhemin, E-mail: zheminxuan@gmail.com [University of Central Florida, Department of Civil, Environmental, and Construction Engineering, 4000 Central Florida Blvd, Building 91, Suite 442, Orlando, FL 32816 (United States); Harris, Willie G., E-mail: apatite@ufl.edu [University of Florida, Soil and Water Science Department, 2169 McCarty Hall, Gainesville, FL 32611 (United States)

    2012-08-15

    Soil beneath a stormwater infiltration basin receiving runoff from a 23 ha predominantly residential watershed in north-central Florida, USA, was amended using biosorption activated media (BAM) to study the effectiveness of this technology in reducing inputs of nitrogen and phosphorus to groundwater. The functionalized soil amendment BAM consists of a 1.0:1.9:4.1 mixture (by volume) of tire crumb (to increase sorption capacity), silt and clay (to increase soil moisture retention), and sand (to promote sufficient infiltration), which was applied to develop an innovative stormwater infiltration basin utilizing nutrient reduction and flood control sub-basins. Comparison of nitrate/chloride (NO{sub 3}{sup -}/Cl{sup -}) ratios for the shallow groundwater indicates that prior to using BAM, NO{sub 3}{sup -} concentrations were substantially influenced by nitrification or variations in NO{sub 3}{sup -} input. In contrast, for the new basin utilizing BAM, NO{sub 3}{sup -}/Cl{sup -} ratios indicate minor nitrification and NO{sub 3}{sup -} losses with the exception of one summer sample that indicated a 45% loss. Biogeochemical indicators (denitrifier activity derived from real-time polymerase chain reaction and variations in major ions, nutrients, dissolved and soil gases, and stable isotopes) suggest that NO{sub 3}{sup -} losses are primarily attributable to denitrification, whereas dissimilatory nitrate reduction to ammonium is a minor process. Denitrification was likely occurring intermittently in anoxic microsites in the unsaturated zone, which was enhanced by the increased soil moisture within the BAM layer and resultant reductions in surface/subsurface oxygen exchange that produced conditions conducive to increased denitrifier activity. Concentrations of total dissolved phosphorus and orthophosphate (PO{sub 4}{sup 3-}) were reduced by more than 70% in unsaturated zone soil water, with the largest decreases in the BAM layer where sorption was the most likely mechanism

  12. Hydro-biogeochemical Controls on Geophysical Signatures (Invited)

    Science.gov (United States)

    Atekwana, E. A.

    2013-12-01

    Geophysical techniques such as seismic, magnetic and electrical techniques have historically played a major role in oil exploration. Their main use has been for delineation basin geometry, structures and hydrocarbon traps and for understanding the subsurface stratigraphy. Their use for investigating microbial processes has only recently been recognized over the last decade resulting in the development of biogeophysics as a frontier research area which bridges the fields of environmental microbiology, biogeochemistry, geomicrobiology. Recent biogeophysical studies have demonstrated the potential of geophysical technologies to (1) probe the presence of microbial cells and biofilms in subsurface geologic media, (2) investigate the interactions between microorganisms and subsurface geologic media, (3) assess biogeochemical transformations, biomineralization, and biogeochemical reaction rates, and (4) investigate the alteration of physical properties of subsurface geologic media induced by microorganisms. The unique properties of geophysical datasets (e.g. non-invasive data acquisition, spatially continuous properties retrieved) make them attractive for probing microbial processes affecting fate and transport of contaminants. This presentation will provide an updated understanding of major controls on geophysical signatures by highlighting some of the important advancements in biogeophysical studies at hydrocarbon contaminated environments. Important challenges that provide an opportunity for further research in this new field will also be examined.

  13. Microbial diversity and biogeochemical cycling in soda lakes.

    Science.gov (United States)

    Sorokin, Dimitry Y; Berben, Tom; Melton, Emily Denise; Overmars, Lex; Vavourakis, Charlotte D; Muyzer, Gerard

    2014-09-01

    Soda lakes contain high concentrations of sodium carbonates resulting in a stable elevated pH, which provide a unique habitat to a rich diversity of haloalkaliphilic bacteria and archaea. Both cultivation-dependent and -independent methods have aided the identification of key processes and genes in the microbially mediated carbon, nitrogen, and sulfur biogeochemical cycles in soda lakes. In order to survive in this extreme environment, haloalkaliphiles have developed various bioenergetic and structural adaptations to maintain pH homeostasis and intracellular osmotic pressure. The cultivation of a handful of strains has led to the isolation of a number of extremozymes, which allow the cell to perform enzymatic reactions at these extreme conditions. These enzymes potentially contribute to biotechnological applications. In addition, microbial species active in the sulfur cycle can be used for sulfur remediation purposes. Future research should combine both innovative culture methods and state-of-the-art 'meta-omic' techniques to gain a comprehensive understanding of the microbes that flourish in these extreme environments and the processes they mediate. Coupling the biogeochemical C, N, and S cycles and identifying where each process takes place on a spatial and temporal scale could unravel the interspecies relationships and thereby reveal more about the ecosystem dynamics of these enigmatic extreme environments.

  14. Microbial Metagenomics Reveals Climate-Relevant Subsurface Biogeochemical Processes.

    Science.gov (United States)

    Long, Philip E; Williams, Kenneth H; Hubbard, Susan S; Banfield, Jillian F

    2016-08-01

    Microorganisms play key roles in terrestrial system processes, including the turnover of natural organic carbon, such as leaf litter and woody debris that accumulate in soils and subsurface sediments. What has emerged from a series of recent DNA sequencing-based studies is recognition of the enormous variety of little known and previously unknown microorganisms that mediate recycling of these vast stores of buried carbon in subsoil compartments of the terrestrial system. More importantly, the genome resolution achieved in these studies has enabled association of specific members of these microbial communities with carbon compound transformations and other linked biogeochemical processes-such as the nitrogen cycle-that can impact the quality of groundwater, surface water, and atmospheric trace gas concentrations. The emerging view also emphasizes the importance of organism interactions through exchange of metabolic byproducts (e.g., within the carbon, nitrogen, and sulfur cycles) and via symbioses since many novel organisms exhibit restricted metabolic capabilities and an associated extremely small cell size. New, genome-resolved information reshapes our view of subsurface microbial communities and provides critical new inputs for advanced reactive transport models. These inputs are needed for accurate prediction of feedbacks in watershed biogeochemical functioning and their influence on the climate via the fluxes of greenhouse gases, CO2, CH4, and N2O.

  15. Global changes in biogeochemical cycles in response to human activities

    Science.gov (United States)

    Moore, Berrien, III; Melillo, Jerry

    1994-01-01

    The main objective of our research was to characterize biogeochemical cycles at continental and global scales in both terrestrial and aquatic ecosystems. This characterization applied to both natural ecosystems and those disturbed by human activity. The primary elements of interest were carbon and nitrogen and the analysis sought to quantify standing stocks and dynamic cycling processes. The translocation of major nutrients from the terrestrial landscape to the atmosphere (via trace gases) and to fluvial systems (via leaching, erosional losses, and point source pollution) were of particular importance to this study. Our aim was to develop the first generation of Earth System Models. Our research was organized around the construction and testing of component biogeochemical models which treated terrestrial ecosystem processes, aquatic nutrient transport through drainage basins, and trace gas exchanges at the continental and global scale. A suite of three complementary models were defined within this construct. The models were organized to operate at a 1/2 degree latitude by longitude level of spatial resolution and to execute at a monthly time step. This discretization afforded us the opportunity to understand the dynamics of the biosphere down to subregional scales, while simultaneously placing these dynamics into a global context.

  16. Benthic contributions to Adriatic and Mediterranean biogeochemical cycles

    Science.gov (United States)

    Capet, Arthur; Lazzari, Paolo; Spagnoli, Federico; Bolzon, Giorgio; Solidoro, Cosimo

    2017-04-01

    The 3D biogeochemical BFM-OGSTM implementation currently exploited operationally in the Copernicus Marine Environment Monitoring Services Mediterranean Sea Monitoring and Forecasting Centre (CMEMS-Med-MFC; Lazzari et al., 2010) has been complemented with a benthic component. The approach followed that of (Capet et al 2016) and involved a vertically integrated benthic module accounting for the effect of environmental bottom conditions on diagenetic rates (aerobic mineralization, denitrification, nitrification) through transfer functions as well as the effect of waves and bottom currents on sediment deposition and resuspension. A balanced climatological year is simulated for various values of the resuspension parameters, using specifically calibrated transfer functions for the Adriatic Sea and generic formulations for the rest of the Mediterranean basin. The results serves the mapping of distinct provinces of the Adriatic Sea based on the benthic contributions biogeochemical budgets and the seasonal variability of benthic-pelagic fluxes. The differences with the non-benthic reference simulation are highlighted in details regarding the Adriatic, and more generally for the entire Mediterranean Sea. Lazzari, P., Teruzzi, A., Salon, S., Campagna, S., Calonaci, C., Colella, S., Tonani, M., Crise, A. (2010). Pre-operational short-term forecasts for Mediterranean Sea biogeochemistry. Ocean Science, 6(1), 25-39. Capet, A., Meysman, F. J., Akoumianaki, I., Soetaert, K., & Grégoire, M. (2016). Integrating sediment biogeochemistry into 3D oceanic models: A study of benthic-pelagic coupling in the Black Sea. Ocean Modelling, 101, 83-100.

  17. The evolution of diatoms and their biogeochemical functions.

    Science.gov (United States)

    Benoiston, Anne-Sophie; Ibarbalz, Federico M; Bittner, Lucie; Guidi, Lionel; Jahn, Oliver; Dutkiewicz, Stephanie; Bowler, Chris

    2017-09-05

    In contemporary oceans diatoms are an important group of eukaryotic phytoplankton that typically dominate in upwelling regions and at high latitudes. They also make significant contributions to sporadic blooms that often occur in springtime. Recent surveys have revealed global information about their abundance and diversity, as well as their contributions to biogeochemical cycles, both as primary producers of organic material and as conduits facilitating the export of carbon and silicon to the ocean interior. Sequencing of diatom genomes is revealing the evolutionary underpinnings of their ecological success by examination of their gene repertoires and the mechanisms they use to adapt to environmental changes. The rise of the diatoms over the last hundred million years is similarly being explored through analysis of microfossils and biomarkers that can be traced through geological time, as well as their contributions to seafloor sediments and fossil fuel reserves. The current review aims to synthesize current information about the evolution and biogeochemical functions of diatoms as they rose to prominence in the global ocean.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Author(s).

  18. Subsurface Biogeochemical Research FY11 Second Quarter Performance Measure

    Energy Technology Data Exchange (ETDEWEB)

    Scheibe, Timothy D.

    2011-03-31

    The Subsurface Biogeochemical Research (SBR) Long Term Measure for 2011 under the Performance Assessment Rating Tool (PART) measure is to "Refine subsurface transport models by developing computational methods to link important processes impacting contaminant transport at smaller scales to the field scale." The second quarter performance measure is to "Provide a report on computational methods linking genome-enabled understanding of microbial metabolism with reactive transport models to describe processes impacting contaminant transport in the subsurface." Microorganisms such as bacteria are by definition small (typically on the order of a micron in size), and their behavior is controlled by their local biogeochemical environment (typically within a single pore or a biofilm on a grain surface, on the order of tens of microns in size). However, their metabolic activity exerts strong influence on the transport and fate of groundwater contaminants of significant concern at DOE sites, in contaminant plumes with spatial extents of meters to kilometers. This report describes progress and key findings from research aimed at integrating models of microbial metabolism based on genomic information (small scale) with models of contaminant fate and transport in aquifers (field scale).

  19. Modelling benthic biophysical drivers of ecosystem structure and biogeochemical response

    Science.gov (United States)

    Stephens, Nicholas; Bruggeman, Jorn; Lessin, Gennadi; Allen, Icarus

    2016-04-01

    The fate of carbon deposited at the sea floor is ultimately decided by biophysical drivers that control the efficiency of remineralisation and timescale of carbon burial in sediments. Specifically, these drivers include bioturbation through ingestion and movement, burrow-flushing and sediment reworking, which enhance vertical particulate transport and solute diffusion. Unfortunately, these processes are rarely satisfactorily resolved in models. To address this, a benthic model that explicitly describes the vertical position of biology (e.g., habitats) and biogeochemical processes is presented that includes biological functionality and biogeochemical response capturing changes in ecosystem structure, benthic-pelagic fluxes and biodiversity on inter-annual timescales. This is demonstrated by the model's ability to reproduce temporal variability in benthic infauna, vertical pore water nutrients and pelagic-benthic solute fluxes compared to in-situ data. A key advance is the replacement of bulk parameterisation of bioturbation by explicit description of the bio-physical processes responsible. This permits direct comparison with observations and determination of key parameters in experiments. Crucially, the model resolves the two-way interaction between sediment biogeochemistry and ecology, allowing exploration of the benthic response to changing environmental conditions, the importance of infaunal functional traits in shaping benthic ecological structure and the feedback the resulting bio-physical processes exert on pore water nutrient profiles. The model is actively being used to understand shelf sea carbon cycling, the response of the benthos to climatic change, food provision and other societal benefits.

  20. Optimization of ozonation process for the reduction of excess sludge production from activated sludge process of sago industry wastewater using central composite design.

    Science.gov (United States)

    Subha, B; Muthukumar, M

    2012-01-01

    Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R(2)) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction.

  1. Human and technical factors in the doses reduction and optimization at Cogema/Marcoule; Facteurs techniques et humains dans la reduction et l'optimisation des doses a Cogema/Marcoule

    Energy Technology Data Exchange (ETDEWEB)

    Bourgogne, J.L. [Cogema, 30 - Marcoule (France)

    1998-07-01

    In the case of Cogema/Marcoule, the constant decrease of radiation doses is attributed to three factors: technical with a surveillance system and doses optimization, relational with the promotion of confidence in teams of radiation protection services as an acceptation factor of radiation protection techniques and psychological with an evolution of minds towards the ALARA approach. (N.C.)

  2. The interventional radiology: means of reduction and optimization of medical personnel exposure; La radiologie interventionnelle: moyens de reduction et d'optimisation de l'exposition du personnel medical

    Energy Technology Data Exchange (ETDEWEB)

    Maccia, C. [Centre d' Assurance de Qualite des Applications Technologiques dans le Domaine de la Sante, CAATS, 92 - Bourg-la-Reine (France); Vano, E.; Gonzalez, L.; Guibelalde, E. [Faculdad de Medicina, Universidad de Madrid (Spain)

    1998-07-01

    The measures envisaged to make an optimization of the radiation protection are in the use of materials adapted to the situation, the use of dosemeters devoted to the doses evaluation for particularly sensitive organs , the introduction of ophthalmic examinations and finally, the information and training of every category of personnel in radiation protection. (N.C.)

  3. Conformational analysis of large and highly disulfide-stabilized proteins by integrating online electrochemical reduction into an optimized H/D exchange mass spectrometry workflow

    DEFF Research Database (Denmark)

    Trabjerg, Esben; Jakobsen, Rasmus Uffe; Mysling, Simon

    2015-01-01

    Analysis of disulfide-bonded proteins by HDX-MS requires effective and rapid reduction of disulfide bonds before enzymatic digestion in order to increase sequence coverage. In a conventional HDX-MS workflow, disulfide bonds are reduced chemically by addition of a reducing agent to the quench...... the electrochemical reduction efficiency during HDX-MS analysis of two particularly challenging disulfide stabilized proteins: a therapeutic IgG1-antibody and Nerve Growth Factor-β (NGF). Several different parameters (flow rate, applied square wave potential as well as the type of labeling- and quench buffer) were......-antibody, respectively. The presented results demonstrate the successful electrochemical reduction during HDX-MS analysis of both a small exceptional tightly disulfide-bonded protein (NGF) as well as the largest protein attempted to date (IgG1-antibody). We envision that online electrochemical reduction...

  4. Estuarine Biogeochemical Dynamics of Nutrients and Organic Carbon in the Columbia River: Observing Transformations Using a Biogeochemical Sensor Network

    Science.gov (United States)

    Needoba, J. A.; Peterson, T. D.; Riseman, S.; Wilkin, M.; Baptista, A. M.

    2015-12-01

    The Columbia River estuary is an ecosystem dominated by both a large river discharge and strong tidal forcing that creates fast currents, intense and variable physical stratification, low water residence times, and large gradients in salinity, temperature and water quality across the river to ocean boundary. Assessing ecosystem function and biogeochemical cycling in this environment is hampered by the inherent variability in both temporal and spatial timescales. In recent years the NSF Science and Technology Center for Coastal Margin Observation and Prediction has established a comprehensive in situ observation network that spans the estuarine gradient and captures variability associated with tides, diel cycles, episodic events, and seasonal changes in the river and ocean end-members. Here we describe the major patterns of variability in nitrate, orthophosphate, fluorescent dissolved organic carbon and related variables that demonstrate the dominant physical forcing and the biogeochemical hotspots within the ecosystem. These hotspots include intertidal lateral bays, the tidal freshwater river, and the estuarine turbidity maxima. Improved understanding of the role of these estuarine hotspots has informed ecosystem stewardship activities related to juvenile salmon survival, hypoxia, and food web structure.

  5. 低碳供应链纵向合作减排的动态优化%Dynamic optimization about vertical cooperation on carbon emissions reduction in low-carbon supply chain

    Institute of Scientific and Technical Information of China (English)

    赵道致; 原白云; 徐春明

    2014-01-01

    基于微分博弈,研究由一个供应商与一个制造商组成的低碳供应链中纵向合作减排的动态优化问题。构建了以制造商占主导、供应商跟随的Stackelberg微分博弈模型,分别得到了制造商和供应商的最优反馈均衡策略及各自的利润最优值函数,推导出产品碳排放量随时间变化的最优轨迹。通过数值算例分析了制造商和供应商的长期合作减排策略对产品碳排放量的影响,为供应链上下游企业开展长期减排合作提供了理论依据。%Dynamic optimization about vertical cooperation on carbon emissions reduction is discussed based on the differential game in a low-carbon supply chain consisting of a single supplier and a single manufacturer. Stackelberg differential game models are built under a supply chain in which the manufacturer is a leader and the supplier is a follower. The optimal feedback equilibrium strategy with long-term cooperation of the supplier and the manufacturer about reducing emissions and their own optimal value function of profits can be obtained respectively, and the optimal trajectory of products’ carbon emissions also can be found. Finally, through a numerical example, it is analyzed how the long-term cooperation strategies on carbon emissions reduction of manufacturer and supplier affect the carbon emissions of product, and the theoretical basis is provided for long-term emissions reduction vertical cooperation in supply chain.

  6. Multimillennium changes in dissolved oxygen under global warming: results from an AOGCM and offline ocean biogeochemical model

    Science.gov (United States)

    Yamamoto, A.; Abe-Ouchi, A.; Shigemitsu, M.; Oka, A.; Takahashi, K.; Ohgaito, R.; Yamanaka, Y.

    2016-12-01

    Long-term oceanic oxygen change due to global warming is still unclear; most future projections (such as CMIP5) are only performed until 2100. Indeed, few previous studies using conceptual models project oxygen change in the next thousands of years, showing persistent global oxygen reduction by about 30% in the next 2000 years, even after atmospheric carbon dioxide stops rising. Yet, these models cannot sufficiently represent the ocean circulation change: the key driver of oxygen change. Moreover, considering serious effect oxygen reduction has on marine life and biogeochemical cycling, long-term oxygen change should be projected for higher validity. Therefore, we used a coupled atmosphere-ocean general circulation model (AOGCM) and an offline ocean biogeochemical model, investigating realistic long-term changes in oceanic oxygen concentration and ocean circulation. We integrated these models for 2000 years under atmospheric CO2 doubling and quadrupling. After global oxygen reduction in the first 500 years, oxygen concentration in deep ocean globally recovers and overshoots, despite surface oxygen decrease and weaker Atlantic Meridional Overturning Circulation. Deep ocean convection in the Weddell Sea recovers and overshoots, after initial cessation. Thus, enhanced deep convection and associated Antarctic Bottom Water supply oxygen-rich surface waters to deep ocean, resulting global deep ocean oxygenation. We conclude that the change in ocean circulation in the Southern Ocean potentially drives millennial-scale oxygenation in the deep ocean; contrary to past reported long-term oxygen reduction and general expectation. In presentation, we will discuss the mechanism of response of deep ocean convection in the Weddell Sea and show the volume changes of hypoxic waters.

  7. TU-EF-204-09: A Preliminary Method of Risk-Informed Optimization of Tube Current Modulation for Dose Reduction in CT

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Y; Liu, B; Kalra, M; Caracappa, P [Rensselaer Polytechnic Institute, Troy, NY (United States); Liu, T; Li, X [Massachusetts General Hospital, Boston, MA (United States); Xu, X [Rensselaer Polytechnic Inst., Troy, NY (United States)

    2015-06-15

    Purpose: X-rays from CT scans can increase cancer risk to patients. Lifetime Attributable Risk of Cancer Incidence for adult patients has been investigated and shown to decrease as patient age. However, a new risk model shows an increasing risk trend for several radiosensitive organs for middle age patients. This study investigates the feasibility of a general method for optimizing tube current modulation (TCM) functions to minimize risk by reducing radiation dose to radiosensitive organs of patients. Methods: Organ-based TCM has been investigated in literature for eye lens dose and breast dose. Adopting the concept in organ-based TCM, this study seeks to find an optimized tube current for minimal total risk to breasts and lungs by reducing dose to these organs. The contributions of each CT view to organ dose are determined through simulations of CT scan view-by-view using a GPU-based fast Monte Carlo code, ARCHER. A Linear Programming problem is established for tube current optimization, with Monte Carlo results as weighting factors at each view. A pre-determined dose is used as upper dose boundary, and tube current of each view is optimized to minimize the total risk. Results: An optimized tube current is found to minimize the total risk of lungs and breasts: compared to fixed current, the risk is reduced by 13%, with breast dose reduced by 38% and lung dose reduced by 7%. The average tube current is maintained during optimization to maintain image quality. In addition, dose to other organs in chest region is slightly affected, with relative change in dose smaller than 10%. Conclusion: Optimized tube current plans can be generated to minimize cancer risk to lungs and breasts while maintaining image quality. In the future, various risk models and greater number of projections per rotation will be simulated on phantoms of different gender and age. National Institutes of Health R01EB015478.

  8. Biogeochemical Modeling of the Second Rise of Atmospheric Oxygen

    Science.gov (United States)

    Smith, M.; Catling, D. C.; Claire, M.

    2014-12-01

    The second rise of atmospheric oxygen (~600 Ma) marked an increase of atmospheric pO2 from a poorly constrained value of 0.1% atmospheric level (PAL) in the early and mid Proterozoic to >10%PAL1. The event is important because it ushered in the modern era of animal life. To understand the evolution of Earth's habitability, it is therefore key to understand the cause of this 2nd rise. Here, we quantitatively examine possible causes for the 2nd rise of oxygen. We use a biogeochemical box model2 originally developed to calculate the oxygen evolution before and after the 1st rise of oxygen (~2.4 Ga). The Claire et al. (2006) model calculates the evolution of atmospheric oxygen and methane given production and loss fluxes associated with the oxygen, carbon, and iron cycles. Because the model was unable to drive pO2 to end-Proterozoic levels, the authors suggested that another buffer, such as sulfur, is needed to explain the 2nd rise of oxygen. The sulfur and oxygen cycles are tied through various biogeochemical interactions; therefore, once sulfur (as sulfate) began to accumulate in Proterozoic oceans, it likely began to heavily influence the oxygen cycle. We have added a sulfur biogeochemical cycle to this model, enabling exploration of mechanisms that buffer pO2 at intermediate levels in the Proterozoic and fail to do so in the Phanerozoic. Preliminary results show evolution of oxygen and methane that are consistent with geologic proxies. However, the model-generated 2nd rise of oxygen is dependent upon sulfur fluxes that have uncertain magnitudes, so we will present the sensitivity of our results to model assumptions while constraining scenarios for the 2nd rise of atmospheric O2. In the future, we will also integrate isotopic fractionation effects, which will allow comparison with isotopic data from sedimentary sulfides, carbonates, and organic carbon. 1Canfield, C., 2014, Treatise on Geochemistry, 197 2Claire, M.W., et al., 2006, Geobiology, 4, 239

  9. Spatial patterns in soil biogeochemical process rates along a Louisiana wetland salinity gradient in the Barataria Bay estuarine system

    Science.gov (United States)

    Roberts, B. J.; Rich, M. W.; Sullivan, H. L.; Bledsoe, R.; Dawson, M.; Donnelly, B.; Marton, J. M.

    2014-12-01

    Louisiana has the highest rates of coastal wetland loss in the United States. In addition to being lost, Louisiana wetlands experience numerous other environmental stressors including changes in salinity regime (both increases from salt water intrusion and decreases from the creation of river diversions) and climate change induced changes in vegetation (e.g. the northward expansion of Avicennia germinans (black mangrove) into salt marshes). In this study, we examined how these changes might influence biogeochemical process rates important in regulating carbon balance and the cycling, retention, and removal of nutrients in Louisiana wetlands. Specifically, we measured net soil greenhouse gas fluxes and collected cores for the determination of rates of greenhouse gas production, denitrification potential, nitrification potential, iron reduction, and phosphorus sorption from surface (0-5cm) and subsurface (10-15cm) depths for three plots in each of 4 sites along the salinity gradient: a freshwater marsh site, a brackish (7 ppt) marsh site, a salt marsh (17 ppt), and a Avicennia germinans stand (17 ppt; adjacent to salt marsh site) in the Barataria Bay estuarine system. Most biogeochemical processes displayed similar spatial patterns with salt marsh rates being lower than rates in freshwater and/or brackish marsh sites and not having significantly different rates than in Avicennia germinans stands. Rates in surface soils were generally higher than in subsurface soils. These patterns were generally consistent with spatial patterns in soil properties with soil water content, organic matter quantity and quality, and extractable nutrients generally being higher in freshwater and brackish marsh sites than salt marsh and Avicennia germinans sites, especially in surface soils. These spatial patterns suggest that the ability of coastal wetlands to retain and remove nutrients might change significantly in response to future climate changes in the region and that these

  10. Reduction of radiation risks in patients undergoing some X-ray examinations by using optimal projections: A Monte Carlo program-based mathematical calculation

    Directory of Open Access Journals (Sweden)

    A Chaparian

    2014-01-01

    Full Text Available The objectives of this paper were calculation and comparison of the effective doses, the risks of exposure-induced cancer, and dose reduction in the gonads for male and female patients in different projections of some X-ray examinations. Radiographies of lumbar spine [in the eight projections of anteroposterior (AP, posteroanterior (PA, right lateral (RLAT, left lateral (LLAT, right anterior-posterior oblique (RAO, left anterior-posterior oblique (LAO, right posterior-anterior oblique (RPO, and left posterior-anterior oblique (LPO], abdomen (in the two projections of AP and PA, and pelvis (in the two projections of AP and PA were investigated. A solid-state dosimeter was used for the measuring of the entrance skin exposure. A Monte Carlo program was used for calculation of effective doses, the risks of radiation-induced cancer, and doses to the gonads related to the different projections. Results of this study showed that PA projection of abdomen, lumbar spine, and pelvis radiographies caused 50%-57% lower effective doses than AP projection and 50%-60% reduction in radiation risks. Also use of LAO projection of lumbar spine X-ray examination caused 53% lower effective dose than RPO projection and 56% and 63% reduction in radiation risk for male and female, respectively, and RAO projection caused 28% lower effective dose than LPO projection and 52% and 39% reduction in radiation risk for males and females, respectively. About dose reduction in the gonads, using of the PA position rather than AP in the radiographies of the abdomen, lumbar spine, and pelvis can result in reduction of the ovaries doses in women, 38%, 31%, and 25%, respectively and reduction of the testicles doses in males, 76%, 86%, and 94%, respectively. Also for oblique projections of lumbar spine X-ray examination, with employment of LAO rather than RPO and also RAO rather than LPO, demonstrated 22% and 13% reductions to the ovaries doses and 66% and 54% reductions in the

  11. INTERACTIVE EFFECTS OF SOLAR UV RADIATION AND CLIMATE CHANGE ON BIOGEOCHEMICAL CYCLING

    Science.gov (United States)

    This paper assesses research on the interactions of UV radiation (280-400 nm) and global climate change with global biogeochemical cycles at the Earth's surface. The effects of UV-B (280-315 nm), which are dependent on the stratospheric ozone layer, on biogeochemical cycles are o...

  12. Modelling of transport and biogeochemical processes in pollution plumes: Vejen landfill, Denmark

    DEFF Research Database (Denmark)

    Brun, A.; Engesgaard, Peter Knudegaard; Christensen, Thomas Højlund;

    2002-01-01

    A biogeochemical transport code is used to simulate leachate attenuation. biogeochemical processes. and development of redox zones in a pollution plume downstream of the Vejen landfill in Denmark. Calibration of the degradation parameters resulted in a good agreement with the observed distribution...

  13. INTERACTIVE EFFECTS OF SOLAR UV RADIATION AND CLIMATE CHANGE ON BIOGEOCHEMICAL CYCLING

    Science.gov (United States)

    This paper assesses research on the interactions of UV radiation (280-400 nm) and global climate change with global biogeochemical cycles at the Earth's surface. The effects of UV-B (280-315 nm), which are dependent on the stratospheric ozone layer, on biogeochemical cycles are o...

  14. Isotope biogeochemical assessment of natural biodegradation processes in open cast pit mining landscapes

    Science.gov (United States)

    Jeschke, Christina; Knöller, Kay; Koschorreck, Matthias; Ussath, Maria; Hoth, Nils

    2014-05-01

    In Germany, a major share of the energy production is based on the burning of lignite from open cast pit mines. The remediation and re-cultivation of the former mining areas in the Lusatian and Central German lignite mining district is an enormous technical and economical challenge. After mine closures, the surrounding landscapes are threatened by acid mine drainage (AMD), i.e. the acidification and mineralization of rising groundwater with metals and inorganic contaminants. The high content of sulfur (sulfuric acid, sulfate), nitrogen (ammonium) and iron compounds (iron-hydroxides) deteriorates the groundwater quality and decelerates sustainable development of tourism in (former) mining landscapes. Natural biodegradation or attenuation (NA) processes of inorganic contaminants are considered to be a technically low impact and an economically beneficial solution. The investigations of the stable isotope compositions of compounds involved in NA processes helps clarify the dynamics of natural degradation and provides specific informations on retention processes of sulfate and nitrogen-compounds in mine dump water, mine dump sediment, and residual pit lakes. In an active mine dump we investigated zones where the process of bacterial sulfate reduction, as one very important NA process, takes place and how NA can be enhanced by injecting reactive substrates. Stable isotopes signatures of sulfur and nitrogen components were examined and evaluated in concert with hydrogeochemical data. In addition, we delineated the sources of ammonium pollution in mine dump sediments and investigated nitrification by 15N-labeling techniques to calculate the limit of the conversion of harmful ammonium to nitrate in residual mining lakes. Ultimately, we provided an isotope biogeochemical assessment of natural attenuation of sulfate and ammonium at mine dump sites and mining lakes. Also, we estimated the risk potential for water in different compartments of the hydrological system. In

  15. Characterization of Coupled Hydrologic-Biogeochemical Processes Using Geophysical Data

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Susan

    2005-06-01

    Biogeochemical and hydrological processes are naturally coupled and variable over a wide range of spatial and temporal scales. Many remediation approaches also induce dynamic transformations in natural systems, such as the generation of gases, precipitates and biofilms. These dynamic transformations are often coupled and can reduce the hydraulic conductivity of the geologic materials, making it difficult to introduce amendments or to perform targeted remediation. Because it is difficult to predict these transformations, our ability to develop effective and sustainable remediation conditions at contaminated sites is often limited. Further complicating the problem is the inability to collect the necessary measurements at a high enough spatial resolution yet over a large enough volume for understanding field-scale transformations.

  16. Differential leaflet mortality may influence biogeochemical cycling following tropical cyclones.

    Science.gov (United States)

    Marler, Thomas E; Ferreras, Ulysses

    2014-01-01

    Intensity of tropical cyclones is expected to increase in the coming century, and an improved understanding of their influence on biogeochemical cycles would benefit ecologists and conservationists. We studied the November 2013 Typhoon Haiyan damage to observe that numerous examples of partial leaf necrosis on intact leaves of trees in the Cycadaceae and Arecaceae families resulted, leaving behind a copious amount of arboreal dead leaf material attached to live leaves. The decay process of this form of arboreal litter has not been previously studied. When compared with decay of ground litter or detached litter suspended in the canopy, we predict the decay process of this form of arboreal litter will include increased photooxidation, leaching, and comminution by detritivorous insects and mites; but decreased catabolism of organic molecules by saprophytic organisms.

  17. Biogeochemical cycling in terrestrial ecosystems - Modeling, measurement, and remote sensing

    Science.gov (United States)

    Peterson, D. L.; Matson, P. A.; Lawless, J. G.; Aber, J. D.; Vitousek, P. M.

    1985-01-01

    The use of modeling, remote sensing, and measurements to characterize the pathways and to measure the rate of biogeochemical cycling in forest ecosystems is described. The application of the process-level model to predict processes in intact forests and ecosystems response to disturbance is examined. The selection of research areas from contrasting climate regimes and sites having a fertility gradient in that regime is discussed, and the sites studied are listed. The use of remote sensing in determining leaf area index and canopy biochemistry is analyzed. Nitrous oxide emission is investigated by using a gas measurement instrument. Future research projects, which include studying the influence of changes on nutrient cycling in ecosystems and the effect of pollutants on the ecosystems, are discussed.

  18. A GIS approach to conducting biogeochemical research in wetlands

    Science.gov (United States)

    Brannon, David P.; Irish, Gary J.

    1985-01-01

    A project was initiated to develop an environmental data base to address spatial aspects of both biogeochemical cycling and resource management in wetlands. Specific goals are to make regional methane flux estimates and site specific water level predictions based on man controlled water releases within a wetland study area. The project will contribute to the understanding of the Earth's biosphere through its examination of the spatial variability of methane emissions. Although wetlands are thought to be one of the primary sources for release of methane to the atmosphere, little is known about the spatial variability of methane flux. Only through a spatial analysis of methane flux rates and the environmental factors which influence such rates can reliable regional and global methane emissions be calculated. Data will be correlated and studied from Landsat 4 instruments, from a ground survey of water level recorders, precipitation recorders, evaporation pans, and supplemental gauges, and from flood gate water release; and regional methane flux estimates will be made.

  19. Biogeochemical controls on mercury methylation in the Allequash Creek wetland.

    Science.gov (United States)

    Creswell, Joel E; Shafer, Martin M; Babiarz, Christopher L; Tan, Sue-Zanne; Musinsky, Abbey L; Schott, Trevor H; Roden, Eric E; Armstrong, David E

    2017-06-01

    We measured mercury methylation potentials and a suite of related biogeochemical parameters in sediment cores and porewater from two geochemically distinct sites in the Allequash Creek wetland, northern Wisconsin, USA. We found a high degree of spatial variability in the methylation rate potentials but no significant differences between the two sites. We identified the primary geochemical factors controlling net methylmercury production at this site to be acid-volatile sulfide, dissolved organic carbon, total dissolved iron, and porewater iron(II). Season and demethylation rates also appear to regulate net methylmercury production. Our equilibrium speciation modeling demonstrated that sulfide likely regulated methylation rates by controlling the speciation of inorganic mercury and therefore its bioavailability to methylating bacteria. We found that no individual geochemical parameter could explain a significant amount of the observed variability in mercury methylation rates, but we found significant multivariate relationships, supporting the widely held understanding that net methylmercury production is balance of several simultaneously occurring processes.

  20. Reconstructing disturbances and their biogeochemical consequences over multiple timescales

    Science.gov (United States)

    McLauchlan, Kendra K.; Higuera, Philip E.; Gavin, Daniel G.; Perakis, Steven S.; Mack, Michelle C.; Alexander, Heather; Battles, John; Biondi, Franco; Buma, Brian; Colombaroli, Daniele; Enders, Sara K.; Engstrom, Daniel R.; Hu, Feng Sheng; Marlon, Jennifer R.; Marshall, John; McGlone, Matt; Morris, Jesse L.; Nave, Lucas E.; Shuman, Bryan; Smithwick, Erica A.H.; Urrego, Dunia H.; Wardle, David A.; Williams, Christopher J.; Williams, Joseph J.

    2014-01-01

    Ongoing changes in disturbance regimes are predicted to cause acute changes in ecosystem structure and function in the coming decades, but many aspects of these predictions are uncertain. A key challenge is to improve the predictability of postdisturbance biogeochemical trajectories at the ecosystem level. Ecosystem ecologists and paleoecologists have generated complementary data sets about disturbance (type, severity, frequency) and ecosystem response (net primary productivity, nutrient cycling) spanning decadal to millennial timescales. Here, we take the first steps toward a full integration of these data sets by reviewing how disturbances are reconstructed using dendrochronological and sedimentary archives and by summarizing the conceptual frameworks for carbon, nitrogen, and hydrologic responses to disturbances. Key research priorities include further development of paleoecological techniques that reconstruct both disturbances and terrestrial ecosystem dynamics. In addition, mechanistic detail from disturbance experiments, long-term observations, and chronosequences can help increase the understanding of ecosystem resilience.

  1. Coupling a Terrestrial Biogeochemical Model to the Common Land Model

    Institute of Scientific and Technical Information of China (English)

    SHI Xiaoying; MAd Jiafu; WANG Yingping; DAI Yongjiu; TANG Xuli

    2011-01-01

    A terrestrial biogeochemical model (CASACNP) was coupled to a land surtace model (the Common Land Model,CoLM) to simulate the dynamics of carbon substrate in soil and its limitation on soil respiration.The combined model,CoLM_CASACNP,was able to predict long-term carbon sources and sinks that CoLM alone could not.The coupled model was tested using measurenents of belowground respiration and surface fluxes from two forest ecosystems.The combined model simulated reasonably well the diurnal and seasonal variations of net ecosystem carbon exchange,as well as seasonal variation in the soil respiration rate of both the forest sites chosen for this study.However,the agreement between model simulations and actual measurements was poorer under dry conditions.The model should be tested against more measurements before being applied globally to investigate the feedbacks between the carbon cycle and climate change.

  2. Isotopic constraints on biogeochemical cycling of copper in the ocean.

    Science.gov (United States)

    Takano, Shotaro; Tanimizu, Masaharu; Hirata, Takafumi; Sohrin, Yoshiki

    2014-12-05

    Trace elements and their isotopes are being actively studied as powerful tracers in the modern ocean and as proxies for the palaeocean. Although distributions and fractionations have been reported for stable isotopes of dissolved Fe, Cu, Zn and Cd in the ocean, the data remain limited and only preliminary explanations have been given. Copper is of great interest because it is either essential or toxic to organisms and because its distribution reflects both biological recycling and scavenging. Here we present new isotopic composition data for dissolved Cu (δ(65)Cu) in seawater and rainwater. The Cu isotopic composition in surface seawater can be explained by the mixing of rain, river and deep seawater. In deep seawater, δ(65)Cu becomes heavier with oceanic circulation because of preferential scavenging of the lighter isotope ((63)Cu). In addition, we constrain the marine biogeochemical cycling of Cu using a new box model based on Cu concentrations and δ(65)Cu.

  3. The NEON Aquatic Network: Expanding the Availability of Biogeochemical Data

    Science.gov (United States)

    Vance, J. M.; Bohall, C.; Fitzgerald, M.; Utz, R.; Parker, S. M.; Roehm, C. L.; Goodman, K. J.; McLaughlin, B.

    2013-12-01

    Aquatic ecosystems are facing unprecedented pressure from climate change and land-use practices. Invasive species, whether plant, animal, insect or microbe present additional threat to aquatic ecosystem services. There are significant scientific challenges to understanding how these forces will interact to affect aquatic ecosystems, as the flow of energy and materials in the environment is driven by multivariate and non-linear biogeochemical cycles. The National Ecological Observatory Network (NEON) will collect and provide observational data across multiple scales. Sites were selected to maximize representation of major North American ecosystems using a multivariate geographic clustering method that partitioned the continental US, AK, HI, and Puerto Rico into 20 eco-climatic domains. The NEON data collection systems and methods are designed to yield standardized, near real-time data subjected to rigorous quality controls prior to public dissemination through an online data portal. NEON will collect data for 30 years to facilitate spatial-temporal analysis of environmental responses and drivers of ecosystem change, ranging from local through continental scales. Here we present the NEON Aquatic Network, a multi-parameter network consisting of a combination of in situ sensor and observational data. This network will provide data to examine biogeochemical, biological, hydrologic and geomorphic metrics at 36 sites, which are a combination of small 1st/2nd order wadeable streams, large rivers and lakes. A typical NEON Aquatic site will host up to two in-stream sensor sets designed to collect near-continuous water quality data (e.g. pH/ORP, temperature, conductivity, dissolved oxygen, CDOM) along with up to 8 shallow groundwater monitoring wells (level, temp., cond.), and a local meteorological station (e.g. 2D wind speed, PAR, barometric pressure, temperature, net radiation). These coupled sensor suites will be complemented by observational data (e.g. water

  4. Biogeochemical versus ecological consequences of modeled ocean physics

    Science.gov (United States)

    Clayton, Sophie; Dutkiewicz, Stephanie; Jahn, Oliver; Hill, Christopher; Heimbach, Patrick; Follows, Michael J.

    2017-06-01

    We present a systematic study of the differences generated by coupling the same ecological-biogeochemical model to a 1°, coarse-resolution, and 1/6°, eddy-permitting, global ocean circulation model to (a) biogeochemistry (e.g., primary production) and (b) phytoplankton community structure. Surprisingly, we find that the modeled phytoplankton community is largely unchanged, with the same phenotypes dominating in both cases. Conversely, there are large regional and seasonal variations in primary production, phytoplankton and zooplankton biomass. In the subtropics, mixed layer depths (MLDs) are, on average, deeper in the eddy-permitting model, resulting in higher nutrient supply driving increases in primary production and phytoplankton biomass. In the higher latitudes, differences in winter mixed layer depths, the timing of the onset of the spring bloom and vertical nutrient supply result in lower primary production in the eddy-permitting model. Counterintuitively, this does not drive a decrease in phytoplankton biomass but results in lower zooplankton biomass. We explain these similarities and differences in the model using the framework of resource competition theory, and find that they are the consequence of changes in the regional and seasonal nutrient supply and light environment, mediated by differences in the modeled mixed layer depths. Although previous work has suggested that complex models may respond chaotically and unpredictably to changes in forcing, we find that our model responds in a predictable way to different ocean circulation forcing, despite its complexity. The use of frameworks, such as resource competition theory, provides a tractable way to explore the differences and similarities that occur. As this model has many similarities to other widely used biogeochemical models that also resolve multiple phytoplankton phenotypes, this study provides important insights into how the results of running these models under different physical conditions

  5. Temporal dynamics of biogeochemical processes at the Norman Landfill site

    Science.gov (United States)

    Arora, Bhavna; Mohanty, Binayak P.; McGuire, Jennifer T.; Cozzarelli, Isabelle M.

    2013-01-01

    The temporal variability observed in redox sensitive species in groundwater can be attributed to coupled hydrological, geochemical, and microbial processes. These controlling processes are typically nonstationary, and distributed across various time scales. Therefore, the purpose of this study is to investigate biogeochemical data sets from a municipal landfill site to identify the dominant modes of variation and determine the physical controls that become significant at different time scales. Data on hydraulic head, specific conductance, δ2H, chloride, sulfate, nitrate, and nonvolatile dissolved organic carbon were collected between 1998 and 2000 at three wells at the Norman Landfill site in Norman, OK. Wavelet analysis on this geochemical data set indicates that variations in concentrations of reactive and conservative solutes are strongly coupled to hydrologic variability (water table elevation and precipitation) at 8 month scales, and to individual eco-hydrogeologic framework (such as seasonality of vegetation, surface-groundwater dynamics) at 16 month scales. Apart from hydrologic variations, temporal variability in sulfate concentrations can be associated with different sources (FeS cycling, recharge events) and sinks (uptake by vegetation) depending on the well location and proximity to the leachate plume. Results suggest that nitrate concentrations show multiscale behavior across temporal scales for different well locations, and dominant variability in dissolved organic carbon for a closed municipal landfill can be larger than 2 years due to its decomposition and changing content. A conceptual framework that explains the variability in chemical concentrations at different time scales as a function of hydrologic processes, site-specific interactions, and/or coupled biogeochemical effects is also presented.

  6. Coastal-zone biogeochemical dynamics under global warming

    Energy Technology Data Exchange (ETDEWEB)

    Mackenzie, F.T.; Ver, L.M.; Lerman, A.

    2000-03-01

    The coastal zone, consisting of the continental shelves to a depth of 200 meters, including bays, lagoons, estuaries, and near-shore banks, is an environment that is strongly affected by its biogeochemical and physical interactions with reservoirs in the adjacent domains of land, atmosphere, open ocean, and marine sediments. Because the coastal zone is smaller in volume and area coverage relative to the open ocean, it traditionally has been studied as an integral part of the global oceans. In this paper, the authors show by numerical modeling that it is important to consider the coastal zone as an entity separate from the open ocean in any assessment of future Earth-system response under human perturbation. Model analyses for the early part of the 21st century suggest that the coastal zone plays a significant modifying role in the biogeochemical dynamics of the carbon cycle and the nutrient cycles coupled to it. This role is manifested in changes in primary production, storage, and/or export of organic matter, its remineralization, and calcium carbonate precipitation--all of which determine the state of the coastal zone with respect to exchange of CO{sub 2} with the atmosphere. Under a scenario of future reduced or complete cessation of the thermohaline circulation (THC) of the global oceans, coastal waters become an important sink for atmospheric CO{sub 2}, as opposed to the conditions in the past and present, when coastal waters are believed to be a source of CO{sub 2} to the atmosphere. Profound changes in coastal-zone primary productivity underscore the important role of phosphorus as a limiting nutrient. In addition, calculations indicate that the saturation state of coastal waters with respect to carbonate minerals will decline by {approximately}15% by the year 2030. Any future slowdown in the THC of the oceans will increase slightly the rate of decline in saturation state.

  7. Watershed Management and Mercury Biogeochemical Cycling in Lake Zapotlan, Mexico

    Science.gov (United States)

    Malczyk, E. A.; Branfireun, B. A.

    2009-05-01

    Lake Zapotlan is an endorheic subtropical eutrophic lake located in Jalisco State, Mexico. The lake supports a small but important local fishery for carp (Cyprinus sp.) and tilapia (Oreochromis sp.) and is an internationally recognized RAMSAR site. Very little research exists in these regions regarding mercury biogeochemical cycling. The lake receives considerable untreated municipal wastewater discharge that is elevated in inorganic total mercury (250-800 ng Hg/L) and organic methylmercury (3-10 ng CH3Hg+/L). The lake is also located on an active fault zone near an active volcano which may cause natural mercury enrichment. To assess a mercury risk to the commercial fishery we investigated the distribution of total inorganic mercury and organic methylmercury in waters, sediments, and fish tissues of the lake, surrounding wetlands, and incoming waters. Although there were high concentrations of inorganic mercury entering the lake in wastewater and seasonal tributary stream flow inputs, average concentrations in lake surface waters (3 ng Hg/L) and sediments (50 ng Hg/gdw) were relatively low. Average concentrations of total inorganic mercury were an order of magnitude higher in water (70 ng Hg/L) and sediment (245 ng Hg/gdw) in wetlands receiving the wastewater discharges. Mercury loading to the main body of the lake is likely reduced by these wetland buffer zones which allow mercury bound to particulate matter to settle out. A similar pattern was seen with respect to methylmercury concentrations. Average concentrations of methylmercury in lake surface water (below detect) and sediment (0.1 ng/gdw) were lower than in impounded wetlands (1 ng CH3Hg+/L, 0.7 ng CH3Hg+/gdw). Mercury concentrations in tilapia (3.5 ng/g) and carp (8 ng/g) from the commercial catch were found to be low in mercury; likely due to a combination of physiological, biogeochemical, and ecological factors.

  8. PFLOTRAN: Recent Developments Facilitating Massively-Parallel Reactive Biogeochemical Transport

    Science.gov (United States)

    Hammond, G. E.

    2015-12-01

    With the recent shift towards modeling carbon and nitrogen cycling in support of climate-related initiatives, emphasis has been placed on incorporating increasingly mechanistic biogeochemistry within Earth system models to more accurately predict the response of terrestrial processes to natural and anthropogenic climate cycles. PFLOTRAN is an open-source subsurface code that is specialized for simulating multiphase flow and multicomponent biogeochemical transport on supercomputers. The object-oriented code was designed with modularity in mind and has been coupled with several third-party simulators (e.g. CLM to simulate land surface processes and E4D for coupled hydrogeophysical inversion). Central to PFLOTRAN's capabilities is its ability to simulate tightly-coupled reactive transport processes. This presentation focuses on recent enhancements to the code that enable the solution of large parameterized biogeochemical reaction networks with numerous chemical species. PFLOTRAN's "reaction sandbox" is described, which facilitates the implementation of user-defined reaction networks without the need for a comprehensive understanding of PFLOTRAN software infrastructure. The reaction sandbox is written in modern Fortran (2003-2008) and leverages encapsulation, inheritance, and polymorphism to provide the researcher with a flexible workspace for prototyping reactions within a massively parallel flow and transport simulation framework. As these prototypical reactions mature into well-accepted implementations, they can be incorporated into PFLOTRAN as native biogeochemistry capability. Users of the reaction sandbox are encouraged to upload their source code to PFLOTRAN's main source code repository, including the addition of simple regression tests to better ensure the long-term code compatibility and validity of simulation results.

  9. Nutrient biogeochemical cycles in the Gulf of Riga: scaling up field studies with a mathematical model

    Science.gov (United States)

    Savchuk, Oleg P.

    2002-05-01

    A box model has been implemented to understand the large-scale biogeochemical cycles of nitrogen, phosphorus, and silicon in the Gulf of Riga. The large data sets collected within the international Gulf of Riga Project in 1993/1995 were used to validate the model. The comparison to data was useful in scaling up to the gulf-wide level and scrutinizing the conclusions based on short-term field surveys and experimental studies. The simulations indicate that the limiting role was passing from silicon to phosphorus to nitrogen over the seasons of organic production. However, on an annual scale, nutrient limitation was close to the "Redfield equilibrium". Mass balance considerations, based on modeled coupled fluxes, disagree with the conclusions on low sediment denitrification and high phosphorus retention in the pelagic system, which were derived from isolated measurements. Nutrient budgets constructed with the model revealed the high buffer capacity of the Gulf of Riga. The nutrient residence times span a range from 6 years for N to 70 years for Si. The buffering arises from intensive internal recycling in the water body and by the bottom sediments. The budgets indicate that the Gulf retains about two-thirds of external nitrogen and silicon inputs, while phosphorus retention is only 10%. A slow response to external perturbations is demonstrated with numerical experiments run for 15 years under 50% reductions of terrestrial nutrient inputs. These experiments imply that the most effective is the N+P reduction scenario, which resulted in a 20% decrease of primary production after 12 years. A reduction of P resulted in only a 6% decrease of primary production; however, it yielded an 80% drop in the amount of nitrogen fixation.

  10. Optimization of MOSFET calibration for in vivo dosimetry in radiosurgery: reduction of measurement uncertainties in pre-clinical conditions; Optimisation de la calibration de MOSFET pour la dosimetrie in vivo en radiochirurgie: reduction des incertitudes de mesure en conditions precliniques

    Energy Technology Data Exchange (ETDEWEB)

    Sors, A.; Berry, I.; Franceries, X. [UMR 825 ' imagerie cerebrale et handicaps neurologiques' , Inserm, Toulouse (France); Cassol, E.; Duthil, P. [Unite de radiophysique et de radioprotection, CHU de Toulouse, Toulouse (France); Hallil, A. [Best medical Canada, Ottawa (Canada); Latorzeff, I.; Lotterie, J.A. [Centre de radiochirurgie stereotaxique, CHU Rangueil, Toulouse (France); Redon, A. [Groupe Oncorad Garonne, Montauban (France)

    2011-10-15

    The objective of this study is to assess the conventional formulas of equivalent square for fields with irregular geometry, by transposing the optimized calibration method which has been previously developed, to micro-MOSFET. The study has been performed on a 6 MV Novalis apparatus equipped with micro-multi-blades collimators (BrainLab). The average dose bias reaches 2.66 per cent for all field sizes. Therefore, it appears that the joint use of the square inverse of distances and of conventional formulas of equivalent square results in an acceptable in vivo dosimetry precision. Short communication

  11. Top-down constraints on atmospheric mercury emissions and implications for global biogeochemical cycling

    Directory of Open Access Journals (Sweden)

    S. Song

    2015-02-01

    Full Text Available We perform global-scale inverse modeling to constrain present-day atmospheric mercury emissions and relevant physio-chemical parameters in the GEOS-Chem chemical transport model. We use Bayesian inversion methods combining simulations with GEOS-Chem and ground-based Hg0 observations from regional monitoring networks and individual sites in recent years. Using optimized emissions/parameters, GEOS-Chem better reproduces these ground-based observations, and also matches regional over-water Hg0 and wet deposition measurements. The optimized global mercury emission to the atmosphere is ~5.8 Gg yr−1. The ocean accounts for 3.2 Gg yr−1 (55% of the total, and the terrestrial ecosystem is neither a net source nor a net sink of Hg0. The optimized Asian anthropogenic emission of Hg0 (gas elemental mercury is 650–1770 Mg yr−1, higher than its bottom-up estimates (550–800 Mg yr−1. The ocean parameter inversions suggest that dark oxidation of aqueous elemental mercury is faster, and less mercury is removed from the mixed layer through particle sinking, when compared with current simulations. Parameter changes affect the simulated global ocean mercury budget, particularly mass exchange between the mixed layer and subsurface waters. Based on our inversion results, we re-evaluate the long-term global biogeochemical cycle of mercury, and show that legacy mercury becomes more likely to reside in the terrestrial ecosystem than in the ocean. We estimate that primary anthropogenic mercury contributes up to 23% of present-day atmospheric deposition.

  12. Reduction of Common-Mode Conducted Noise Emissions in PWM Inverter-fed AC Motor Drive Systems using Optimized Passive EMI Filter

    Science.gov (United States)

    Jettanasen, C.; Ngaopitakkul, A.

    2010-10-01

    Conducted electromagnetic interference (EMI) generated by PWM inverter-fed induction motor drive systems, which are currently widely used in many industrial and/or avionic applications, causes severe parasitic current problems, especially at high frequencies (HF). These restrict power electronic drive's evolution. In order to reduce or minimize these EMI problems, several techniques can be applied. In this paper, insertion of an optimized passive EMI filter is proposed. This filter is optimized by taking into account real impedances of each part of a considered AC motor drive system contrarily to commercial EMI filters designed by considering internal impedance of disturbance source and load, equal to 50Ω. Employing the latter EMI filter would make EMI minimization less effective. The proposed EMI filter optimization is mainly dedicated to minimize common mode (CM) currents due to its most dominant effects in this kind of system. The efficiency of the proposed optimization method using two-port network approach is deduced by comparing the minimized CM current spectra to an applied normative level (ex. DO-160D in aeronautics).

  13. Optimal Active Sound-Reduction in Airplane-Cubicles for High Tonal Noise-Levels (optimale aktive gerauschreduzierung in flugzeugkabinen fur hohe tonale larmpegel)

    Science.gov (United States)

    2005-08-01

    verglichen. Rechenzeiten Die benbtigten Rechenzeiten sind in Tab. 5.2 aufgef~hrt. Wie zu erwarten war, liegen die Rechenzeiten von COSA wesentlich Uber ...of optimal design: modeling and computation. 2. Aufl. Cambridge: Cambridge University Press, 2000. [Pareto7l] Pareto, V.: Manual of political economy

  14. Coupled physical/biogeochemical modeling including O2-dependent processes in the Eastern Boundary Upwelling Systems: application in the Benguela

    Directory of Open Access Journals (Sweden)

    E. Gutknecht

    2013-06-01

    Full Text Available The Eastern Boundary Upwelling Systems (EBUS contribute to one fifth of the global catches in the ocean. Often associated with Oxygen Minimum Zones (OMZs, EBUS represent key regions for the oceanic nitrogen (N cycle. Important bioavailable N loss due to denitrification and anammox processes as well as greenhouse gas emissions (e.g, N2O occur also in these EBUS. However, their dynamics are currently crudely represented in global models. In the climate change context, improving our capability to properly represent these areas is crucial due to anticipated changes in the winds, productivity, and oxygen content. We developed a biogeochemical model (BioEBUS taking into account the main processes linked with EBUS and associated OMZs. We implemented this model in a 3-D realistic coupled physical/biogeochemical configuration in the Namibian upwelling system (northern Benguela using the high-resolution hydrodynamic ROMS model. We present here a validation using in situ and satellite data as well as diagnostic metrics and sensitivity analyses of key parameters and N2O parameterizations. The impact of parameter values on the OMZ off Namibia, on N loss, and on N2O concentrations and emissions is detailed. The model realistically reproduces the vertical distribution and seasonal cycle of observed oxygen, nitrate, and chlorophyll a concentrations, and the rates of microbial processes (e.g, NH4+ and NO2− oxidation, NO3− reduction, and anammox as well. Based on our sensitivity analyses, biogeochemical parameter values associated with organic matter decomposition, vertical sinking, and nitrification play a key role for the low-oxygen water content, N loss, and N2O concentrations in the OMZ. Moreover, the explicit parameterization of both steps of nitrification, ammonium oxidation to nitrate with nitrite as an explicit intermediate, is necessary to improve the representation of microbial activity linked with the OMZ. The simulated minimum oxygen

  15. Shock Control Bump Optimization for Drag Reduction Using Parallel Efficient Global Optimization Algorithm%基于并行EGO算法的激波控制鼓包减阻优化

    Institute of Scientific and Technical Information of China (English)

    邓枫; 覃宁; 伍贻兆

    2013-01-01

    建立了并行EGO全局优化算法框架,并将其应用于二维和三维激波控制鼓包减阻优化设计当中.EGO全局优化算法是一类基于克里金(Kriging)代理模型的全局优化算法,具有自动平衡全局搜索与局部搜索的优点,适合于处理具有少量设计参数但是函数计算耗时很长的优化问题,例如基于计算流体力学的气动优化设计.为考察并行EGO全局优化算法的效率,选用了4个解析优化算例以及二维和三维激波控制鼓包减阻优化问题对克里金信任法、常数取代法以及罚点法等3种启发式并行策略进行了比较.数值实验表明,并行EGO全局优化算法每次取点个数可多达16个之多,加速将近16倍,其中在3种并行策略中又以罚点法效率最高,因而在计算耗时很长的气动外形优化问题当中具有很大的应用前景.%The parallel efficient global optimization (EGO) algorithm is applied to the 2-D/3-D shock control bump optimizations.The EGO algorithm is a global optimization method based on the Kriging model,which is especially designed for expensive black box functions,such as high-fidelity aerodynamic shape optimizations.Three heuristic parallel strategies including "Kriging believer","constant liar" and " imputed point" strategies are investigated based on four benchmark optimization problems and two shock control bump optimization problems.In shock control bump optimization problems,the parallel EGO algorithm is nearly 16 times faster than the serial EGO algorithm.And our research also shows that' Imputed point' strategy is the best strategy in these optimization problems.

  16. Reduction of belt CVT gear noise by gear train modification. Optimize vibration characteristics of gear train; Belt CVT no gear noise teigen gijutsu. Gear train shindo tokusei no saitekika

    Energy Technology Data Exchange (ETDEWEB)

    Arimatsu, M.; Kawakami, T. [Nissan Motor Co. Ltd., Tokyo (Japan)

    1997-10-01

    With the reduction of vehicle noise, the requirements for an efficient method to reduce transmission gear noise have become stronger yearly. So far efforts to reduce gear noise have generally focused on ways of improving the gears themselves. In addition to these traditional methods, it proved very beneficial to us to optimize the gear train structure. Nissan has just released the new Belt CVT for 2.0L Front wheel drive vehicles. We have been analyzing vibration of the gear train by using a finite element model since the early development stage, and we could achieve the quiet gears effectively. 2 refs., 9 figs.

  17. Bio-geochemical mechanisms influencing the stability of As-bearing iron oxides

    Science.gov (United States)

    Garrido, F.; Dictor, M. C.; Morin, G.; Bodénan, F.; Baranger, P.

    2003-04-01

    Hydrous Ferric Oxydes (HFO) often occurring in the organo-mineral matrix of soils and sediments act as a preferential substrate for the fixation of toxic metals and metalloids as arsenic. The chemical stability of these complexes strongly depends on the physico-chemical and biological conditions of the medium. In this context, the aim of this work was to study mobility factors of arsenic by analogy with bio-geochemical reactions involved in soils and sediments. We studied the conditions of arsenic release in solution upon the reaction of synthetic As-doped iron-oxide minerals with specific micro-organisms (Fe(III)-reducing bacteria or As(V)-reducing bacteria) under controlled laboratory conditions. Our results showed that As release in solution proceeds in two step. First, a rapid As release in solution is caused by competitive sorption processes with other oxy-anions present in the culture medium. In a second step, the microbial reduction of Fe(III) and/or As(V) become the main factor affecting the stability of the As-iron oxide complexes. These two mechanisms were regulated by the physico-chemical conditions of the medium (pH, Eh and phosphate concentration). These results should help in a better understanding of the arsenic mobility in polluted environment. They confirm the major influence of the biological factor on the stability of the As trapping by HFO. This latter chemical trapping mechanism being involved in numerous As water-treatment processes.

  18. Performance and results of the high-resolution biogeochemical model PELAGOS025 within NEMO

    Directory of Open Access Journals (Sweden)

    I. Epicoco

    2015-12-01

    Full Text Available The present work aims at evaluating the scalability performance of a high-resolution global ocean biogeochemistry model (PELAGOS025 on massive parallel architectures and the benefits in terms of the time-to-solution reduction. PELAGOS025 is an on-line coupling between the physical ocean model NEMO and the BFM biogeochemical model. Both the models use a parallel domain decomposition along the horizontal dimension. The parallelisation is based on the message passing paradigm. The performance analysis has been done on two parallel architectures, an IBM BlueGene/Q at ALCF (Argonne Leadership Computing Facilities and an IBM iDataPlex with Sandy Bridge processors at CMCC (Euro Mediterranean Center on Climate Change. The outcome of the analysis demonstrated that the lack of scalability is due to several factors such as the I/O operations, the memory contention, the load unbalancing due to the memory structure of the BFM component and, for the BlueGene/Q, the absence of a hybrid parallelisation approach.

  19. Did large animals play an important role in global biogeochemical cycling in the past?

    Science.gov (United States)

    Doughty, C.

    2014-12-01

    In the late Pleistocene (~50-10,000 years ago), ninety-seven genera of large animals (>44kg) (megafauna) went extinct, concentrated in the Americas and Australia. The loss of megafauna had major effects on ecosystem structure, seed dispersal and land surface albedo. However, the impact of this dramatic extinction on ecosystem nutrient biogeochemistry, through the lateral transport of dung and bodies, has never been explored. Here we explore these nutrient impacts using a novel mathematical framework that analyses this lateral transport as a diffusion-like process and demonstrates that large animals play a disproportionately large role in the horizontal transfer of nutrients across landscapes. For example, we estimate that the extinction of the Amazonian megafauna led to a >98% reduction in the lateral transfer flux of the limiting nutrient phosphorus (P) with similar, though less extreme, decreases in all continents outside of Africa. This resulted in strong decreases in phosphorus availability in Eastern Amazonia away from fertile floodplains, a decline which may still be ongoing, and current P limitation in the Amazon basin may be partially a relic of an ecosystem without the functional connectedness it once had. More broadly, the Pleistocene megafaunal extinctions resulted in major and ongoing disruptions to terrestrial biogeochemical cycling at continental scales and increased nutrient heterogeneity globally.

  20. Evaluation of the transport matrix method for simulation of ocean biogeochemical tracers

    Science.gov (United States)

    Kvale, Karin F.; Khatiwala, Samar; Dietze, Heiner; Kriest, Iris; Oschlies, Andreas

    2017-06-01

    Conventional integration of Earth system and ocean models can accrue considerable computational expenses, particularly for marine biogeochemical applications. Offline numerical schemes in which only the biogeochemical tracers are time stepped and transported using a pre-computed circulation field can substantially reduce the burden and are thus an attractive alternative. One such scheme is the transport matrix method (TMM), which represents tracer transport as a sequence of sparse matrix-vector products that can be performed efficiently on distributed-memory computers. While the TMM has been used for a variety of geochemical and biogeochemical studies, to date the resulting solutions have not been comprehensively assessed against their online counterparts. Here, we present a detailed comparison of the two. It is based on simulations of the state-of-the-art biogeochemical sub-model embedded within the widely used coarse-resolution University of Victoria Earth System Climate Model (UVic ESCM). The default, non-linear advection scheme was first replaced with a linear, third-order upwind-biased advection scheme to satisfy the linearity requirement of the TMM. Transport matrices were extracted from an equilibrium run of the physical model and subsequently used to integrate the biogeochemical model offline to equilibrium. The identical biogeochemical model was also run online. Our simulations show that offline integration introduces some bias to biogeochemical quantities through the omission of the polar filtering used in UVic ESCM and in the offline application of time-dependent forcing fields, with high latitudes showing the largest differences with respect to the online model. Differences in other regions and in the seasonality of nutrients and phytoplankton distributions are found to be relatively minor, giving confidence that the TMM is a reliable tool for offline integration of complex biogeochemical models. Moreover, while UVic ESCM is a serial code, the TMM can

  1. Patterns of Transcript Abundance of Eukaryotic Biogeochemically-Relevant Genes in the Amazon River Plume

    Science.gov (United States)

    Allen, Andrew E.; Carpenter, Edward J.; Coles, Victoria J.; Crump, Byron C.; Doherty, Mary; Foster, Rachel A.; Goes, Joaquim I.; Gomes, Helga R.; Hood, Raleigh R.; McCrow, John P.; Montoya, Joseph P.; Moustafa, Ahmed; Satinsky, Brandon M.; Sharma, Shalabh; Smith, Christa B.; Yager, Patricia L.; Paul, John H.

    2016-01-01

    The Amazon River has the largest discharge of all rivers on Earth, and its complex plume system fuels a wide array of biogeochemical processes, across a large area of the western tropical North Atlantic. The plume thus stimulates microbial processes affecting carbon sequestration and nutrient cycles at a global scale. Chromosomal gene expression patterns of the 2.0 to 156 μm size-fraction eukaryotic microbial community were investigated in the Amazon River Plume, generating a robust dataset (more than 100 million mRNA sequences) that depicts the metabolic capabilities and interactions among the eukaryotic microbes. Combining classical oceanographic field measurements with metatranscriptomics yielded characterization of the hydrographic conditions simultaneous with a quantification of transcriptional activity and identity of the community. We highlight the patterns of eukaryotic gene expression for 31 biogeochemically significant gene targets hypothesized to be valuable within forecasting models. An advantage to this targeted approach is that the database of reference sequences used to identify the target genes was selectively constructed and highly curated optimizing taxonomic coverage, throughput, and the accuracy of annotations. A coastal diatom bloom highly expressed nitrate transporters and carbonic anhydrase presumably to support high growth rates and enhance uptake of low levels of dissolved nitrate and CO2. Diatom-diazotroph association (DDA: diatoms with nitrogen fixing symbionts) blooms were common when surface salinity was mesohaline and dissolved nitrate concentrations were below detection, and hence did not show evidence of nitrate utilization, suggesting they relied on ammonium transporters to aquire recently fixed nitrogen. These DDA blooms in the outer plume had rapid turnover of the photosystem D1 protein presumably caused by photodegradation under increased light penetration in clearer waters, and increased expression of silicon transporters as

  2. Iron: A Biogeochemical Engine That Drives Carbon, Nitrogen, and Phosphorus Cycling in Humid Tropical Forest Soils

    Science.gov (United States)

    Silver, W. L.; Hall, S. J.; Thompson, A.; Yang, W. H.

    2014-12-01

    The abundance of redox active Fe minerals has the potential to alter the storage and loss of C, contribute to gaseous N emissions, and control P retention in upland tropical forest soils. High concentrations of short-range order Fe minerals led to Fe(II) production rates of 26-206 μg g d-1 under short-term low redox conditions (Chacón et al. 2006, Liptzin and Silver 2009, Dubinsky et al. 2010). Potential C mineralization from Fe(II) reduction was 34-263 g CO2-C m-2 y-1, C losses equivalent to approximately 10-60 % of annual litterfall production in this forest. Decreased acidity during Fe reduction can destabilize soil aggregates and lead to C losses. Iron is rapidly reoxidized during aerobic periods, which can subsequently lead to C stabilization via complexation reactions. Fe oxidation can also stimulate C losses via pH-driven dissolved organic C production and directly via Fenton reactions. In laboratory experiments, rates of CO2 production were strongly linearly correlated with Fe(II) loss under aerobic conditions, increasing by 0.51 ± 0.02 µg CO2-C g soil h-1 respired for each mg of Fe(II) g-1 soil oxidized or sorbed (Hall and Silver 2013). Iron oxidation has also been linked to dissimilatory NO3- reduction to NH4+ leading to N retention in ecosystems. Fe(III) reduction coupled with NH4+ oxidation (Feammox) can lead to N losses as dinitrogen gas (N2) or nitrous oxide (N2O), a potent greenhouse gas. Estimates suggest that Feammox resulted in gaseous N losses of 1-4 kg N ha-1 y-1 (Yang et al. 2012), rates equivalent to total denitrification in this forest. Oxidized Fe can strongly bind P decreasing it's availability to plant roots. While this is commonly cited as a potential limitation to net primary production in tropical forests, it also helps to retain P in ecosystems with high rainfall and potential leaching losses. Microbial biomass P availability increased significantly with Fe(II) production, suggesting the P mobilized during Fe(II) reduction was

  3. BRIE: The Penn State Biogeochemical Research Initiative for Education

    Science.gov (United States)

    Freeman, K. H.; Brantley, S. L.; Brenchley, J.

    2003-12-01

    Few scientists are prepared to address the interdisciplinary challenges of biogeochemical research due to disciplinary differences in vocabulary, technique, and scientific paradigm. Thus scientists and engineers trained in traditional disciplines bring a restricted view to the study of environmental systems, which can limit their ability to exploit new techniques and opportunities for scientific advancement. Although the literature is effusive with enthusiasm for interdisciplinary approaches to biogeochemistry, there remains the basic difficulty of cross-training geological and biological scientists. The NSF-IGERT funded Biogeochemical Research Initiative for Education (BRIE) program at Penn State is specifically designed to break down both disciplinary and institutional barriers and it has fostered cross-disciplinary collaboration and training since 1999. Students and faculty are drawn from environmental engineering, geochemistry, soil science, chemistry and microbiology, and the program is regarded on the Penn State campus as a successful example of how interdisciplinary science can best be promoted. There are currently 23 Ph.D. students funded by the program, with an additional 7 affiliated students. At present, a total of 6 students have completed doctoral degrees, and they have done so within normal timeframes. The program is "discipline-plus," whereby students enroll in traditional disciplinary degree programs, and undertake broad training via 12 credits of graduate coursework in other departments. Students are co-advised by faculty from different disciplines, and engage in interdisciplinary research facilitated by research "credit cards." Funding is available for international research experiences, travel to meetings, and other opportunities for professional development. Students help institutionalize interdisciplinary training by designing and conducting a teaching module that shares their expertise with a class in another department or discipline

  4. Complexity, accuracy and practical applicability of different biogeochemical model versions

    Science.gov (United States)

    Los, F. J.; Blaas, M.

    2010-04-01

    The construction of validated biogeochemical model applications as prognostic tools for the marine environment involves a large number of choices particularly with respect to the level of details of the .physical, chemical and biological aspects. Generally speaking, enhanced complexity might enhance veracity, accuracy and credibility. However, very complex models are not necessarily effective or efficient forecast tools. In this paper, models of varying degrees of complexity are evaluated with respect to their forecast skills. In total 11 biogeochemical model variants have been considered based on four different horizontal grids. The applications vary in spatial resolution, in vertical resolution (2DH versus 3D), in nature of transport, in turbidity and in the number of phytoplankton species. Included models range from 15 year old applications with relatively simple physics up to present state of the art 3D models. With all applications the same year, 2003, has been simulated. During the model intercomparison it has been noticed that the 'OSPAR' Goodness of Fit cost function (Villars and de Vries, 1998) leads to insufficient discrimination of different models. This results in models obtaining similar scores although closer inspection of the results reveals large differences. In this paper therefore, we have adopted the target diagram by Jolliff et al. (2008) which provides a concise and more contrasting picture of model skill on the entire model domain and for the entire period of the simulations. Correctness in prediction of the mean and the variability are separated and thus enhance insight in model functioning. Using the target diagrams it is demonstrated that recent models are more consistent and have smaller biases. Graphical inspection of time series confirms this, as the level of variability appears more realistic, also given the multi-annual background statistics of the observations. Nevertheless, whether the improvements are all genuine for the particular

  5. Suspended Particles: Their Role in Estuarine Biogeochemical Cycles

    Science.gov (United States)

    Turner, A.; Millward, G. E.

    2002-12-01

    Suspended particles are instrumental in controlling the reactivity, transport and biological impacts of substances in aquatic environments, and provide a crucial link for chemical constituents between the water column, bed sediment and food chain. This article reviews the role of suspended particles in the chemical and biological cycling of trace constituents (trace metals, organo-metallic compounds and hydrophobic organic micropollutants; HOMs) in estuaries, with particular emphasis on the effects of and changes to particle reactivity and composition. The partitioning (or distribution coefficient, KD ) and bioavailability of chemical constituents, and assimilation efficiency (AE) of such by bivalve suspension feeders, are identified as key parameters requiring definition for accurate biogeochemical modelling, and the discussion centres around the determination of and controls on these parameters. Particle-water interactions encompass a variety of physical, biological, electrostatic and hydrophobic effects, and are largely dependent on the character and concentration of suspended particles and salinity. The salinity-dependence results from the competing and complexing effects of seawater ions for trace metals, and the compression of water in the presence of dissolved seawater ions and consequent salting out of neutral solute (HOMs, organo-metallic compounds and some trace metal complexes). The extent of biological solubilization of chemical constituents from suspended particles is dependent on the nature of chemical components of the gastro-intestinal environment and their interactions with ingested particles, and the physiological (e.g. gut passage time) and chemical (e.g. redox conditions and pH) constraints imposed on these interactions. Generally, chemicals that associate with fine, organic-rich particles (or, for some HOMs, fine inorganic particles), and desorb at pH 5-6 and/or complex with digestive enzymes or surfactants are most readily solubilized in the

  6. Pore-scale insights to the rate of organic carbon degradation and biofilm formation under variable hydro-biogeochemical conditions in soils and sediments

    Science.gov (United States)

    Liu, C.; Yan, Z.; Liu, Y.; Li, M.; Bailey, V. L.

    2015-12-01

    Biogeochemical processes that control microbial growth, organic carbon degradation, and CO2 production and migration are fundamentally occur at the pore scale. In this presentation, we will describe our recent results of a pore-scale simulation research to investigate: 1) how moisture content and distribution affects oxygen delivery, organic carbon availability, and microbial activities that regulate the rate of organic carbon degradation and CO2 production in aerobic systems; and 2) how pore-scale reactive transport processes affect local microbial growth, biofilm formation, and overall rate of microbial reactions in anoxic systems. The results revealed that there is an optimal moisture content for aerobic bacterial respiration and CO2 production. When moisture is below the optimal value, organic carbon availability limits its degradation due to diffusion and osmotic stress to bacterial reactivity; and when moisture is above the optimal value, oxygen delivery limits microbial respiration. The optimal moisture condition is, however, a function of soil texture and physical heterogeneity, bioavailable soil organic carbon, and microbial community function. In anoxic and saturated system, simulation results show that biofilm preferentially forms in concave areas around sand particles and macro aggregates where cross-directional fluxes of organic carbon and electron acceptors (e.g., nitrate) favor microbial growth and attachment. The results provide important insights to the establishment of constitutive relationships between the macroscopic rates of soil organic carbon degradation and moisture content, and to the development of biogeochemical reactive transport models that incorporate biofilm structures and physio-chemical heterogeneity in soils and sediments.

  7. High-resolution mineralogical characterization and biogeochemical modeling of uranium reaction pathways at the FRC

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhu

    2006-06-15

    High-Resolution Mineralogical Characterization and Biogeochemical Modeling of Uranium Reduction Pathways at the Oak Ridge Field-Research Center (FRC) Chen Zhu, Indiana University, David R. Veblen, Johns Hopkins University We have successfully completed a proof-of-concept, one-year grant on a three-year proposal from the former NABIR program, and here we seek additional two-year funding to complete and publish the research. Using a state-of-the-art 300-kV, atomic resolution, Field Emission Gun Transmission Electron Microscope (TEM), we have successfully identified three categories of mineral hosts for uranium in contaminated soils: (1) iron oxides; (2) mixed manganese-iron oxides; and (3) uranium phosphates. Method development using parallel electron energy loss spectroscopy (EELS) associated with the TEM shows great promise for characterizing the valence states of immobilized U during bioremediation. We have also collected 27 groundwater samples from two push-pull field biostimulation tests, which form two time series from zero to approximately 600 hours. The temporal evolution in major cations, anions, trace elements, and the stable isotopes 34S, 18O in sulfate, 15N in nitrate, and 13C in dissolved inorganic carbon (DIC) clearly show that biostimulation resulted in reduction of nitrate, Mn(IV), Fe(III), U(VI), sulfate, and Tc(VII), and these reduction reactions were intimately coupled with a complex network of inorganic reactions evident from alkalinity, pH, Na, K, Mg, and Ca concentrations. From these temporal trends, apparent zero order rates were regressed. However, our extensive suite of chemical and isotopic data sets, perhaps the first and only comprehensive data set available at the FRC, show that the derived rates from these field biostimulation experiments are composite and lump-sum rates. There were several reactions that were occurring at the same time but were masked by these pseudo-zero order rates. A reaction-path model comprising a total of nine

  8. Hippocampal dose from stereotactic radiosurgery for 4 to 10 brain metastases: Risk factors, feasibility of dose reduction via re-optimization, and patient outcomes.

    Science.gov (United States)

    Birer, Samuel R; Olson, Adam C; Adamson, Justus; Hood, Rodney; Susen, Matthew; Kim, Grace; Salama, Joseph K; Kirkpatrick, John P

    2017-07-28

    This study aimed to report hippocampal dose from single-fraction stereotactic radiosurgery (SRS) for 4 to 10 brain metastases and determine feasibility of hippocampal-sparing SRS. Patients with 4 to 10 brain metastases receiving single-isocenter, multi-target single-fraction SRS were identified. Hippocampi were contoured using the Radiation Therapy Oncology Group (RTOG) 0933 atlas. RTOG 0933 dose constraints were converted to a biologically effective dose using an alpha/beta of 2 (D100 421 cGy, Dmax 665 cGy). Number of metastases, total target volume, prescribed dose, and distance of nearest metastasis (dmin) were analyzed as risk factors for exceeding hippocampal constraints. If hippocampi exceeded constraints, the SRS plan was re-optimized. Key dosimetric parameters were compared between original and re-optimized plans. To determine if a single target can exceed constraints, all targets but the closest metastasis were removed from the plan, and dosimetry was compared. Forty plans were identified. Fifteen hippocampi (19%) exceeded constraints in 12 SRS plans. Hippocampal sparing was achieved in 10 of 12 replanned cases (83%). Risk factors associated with exceeding hippocampal constraints were decreasing dmin (24.0 vs 8.0 mm, p = 0.002; odds ratio [OR] 1.14, 95% confidence interval [CI] 1.04 to 1.26) and total target volume (5.46 cm(3)vs 1.98 cm(3), p = 0.03; OR 1.14, 95% CI 1.00 to 1.32). There was no difference in exceeding constraints for 4 to 5 vs 6 to 10 metastases (27% vs 21%, p = 0.409) or prescribed dose (18 Gy, p = 0.58). For re-optimized plans, there were no significant differences in planning target volume (PTV) coverage (99.6% vs 99.0%, p = 0.17) or conformality index (1.47 vs 1.4, p = 0.78). Six (50%) plans exceeded constraints with a single target. A substantial minority of hippocampi receive high radiation dose from SRS for 4 to 10 brain metastases. Decreasing distance of the closest metastasis and total target volume

  9. Impact of sulfate pollution on anaerobic biogeochemical cycles in a wetland sediment.

    Science.gov (United States)

    Baldwin, Darren S; Mitchell, Alison

    2012-03-15

    The impact of sulfate pollution is increasingly being seen as an issue in the management of inland aquatic ecosystems. In this study we use sediment slurry experiments to explore the addition of sulfate, with or without added carbon, on the anaerobic biogeochemical cycles in a wetland sediment that previously had not been exposed to high levels of sulfate. Specifically we looked at the cycling of S (sulfate, dissolved and particulate sulfide--the latter measured as acid volatile sulfide; AVS), C (carbon dioxide, bicarbonate, methane and the short chain volatile fatty acids formate, acetate, butyrate and propionate), N (dinitrogen, ammonium, nitrate and nitrite) and redox active metals (Fe(II) and Mn(II)). Sulfate had the largest effects on the cycling of S and C. All the added S at lower loadings were converted to AVS over the course of the experiment (30 days). At the highest loading (8 mmol) less than 50% of consumed S was converted to AVS, however this is believed to be a kinetic effect. Although sulfate reduction was occurring in sediments with added sulfate, dissolved sulfide concentrations remained low throughout the study. Sulfate addition affected methanogenesis. In the absence of added carbon, addition of sulfate, even at a loading of 1 mmol, resulted in a halving of methane formation. The initial rate of formation of methane was not affected by sulfate if additional carbon was added to the sediment. However, there was evidence for anaerobic methane oxidation in those sediments with added sulfate and carbon, but not in those sediments treated only with carbon. Surprisingly, sulfate addition had little apparent impact on N dynamics; previous studies have shown that sulfide can inhibit denitrification and stimulate dissimilatory nitrate reduction to ammonia. We propose that because most of the reduced sulfur was in particulate form, levels of dissolved sulfide were too low to interfere with the N cycle.

  10. Soil property control of biogeochemical processes beneath two subtropical stormwater infiltration basins

    Science.gov (United States)

    O'Reilly, Andrew M.; Wanielista, Martin P.; Chang, Ni-Bin; Harris, Willie G.; Xuan, Zhemin

    2012-01-01

    Substantially different biogeochemical processes affecting nitrogen fate and transport were observed beneath two stormwater infiltration basins in north-central Florida. Differences are related to soil textural properties that deeply link hydroclimatic conditions with soil moisture variations in a humid, subtropical climate. During 2008, shallow groundwater beneath the basin with predominantly clayey soils (median, 41% silt+clay) exhibited decreases in dissolved oxygen from 3.8 to 0.1 mg L-1 and decreases in nitrate nitrogen (NO3-–N) from 2.7 mg L-1 to -1, followed by manganese and iron reduction, sulfate reduction, and methanogenesis. In contrast, beneath the basin with predominantly sandy soils (median, 2% silt+clay), aerobic conditions persisted from 2007 through 2009 (dissolved oxygen, 5.0–7.8 mg L-1), resulting in NO3-–N of 1.3 to 3.3 mg L-1 in shallow groundwater. Enrichment of d15N and d18O of NO3- combined with water chemistry data indicates denitrification beneath the clayey basin and relatively conservative NO3- transport beneath the sandy basin. Soil-extractable NO3-–N was significantly lower and the copper-containing nitrite reductase gene density was significantly higher beneath the clayey basin. Differences in moisture retention capacity between fine- and coarse-textured soils resulted in median volumetric gas-phase contents of 0.04 beneath the clayey basin and 0.19 beneath the sandy basin, inhibiting surface/subsurface oxygen exchange beneath the clayey basin. Results can inform development of soil amendments to maintain elevated moisture content in shallow soils of stormwater infiltration basins, which can be incorporated in improved best management practices to mitigate NO3- impacts.

  11. Determination of dominant biogeochemical processes in a contaminated aquifer-wetland system using multivariate statistical analysis

    Science.gov (United States)

    Baez-Cazull, S. E.; McGuire, J.T.; Cozzarelli, I.M.; Voytek, M.A.

    2008-01-01

    Determining the processes governing aqueous biogeochemistry in a wetland hydrologically linked to an underlying contaminated aquifer is challenging due to the complex exchange between the systems and their distinct responses to changes in precipitation, recharge, and biological activities. To evaluate temporal and spatial processes in the wetland-aquifer system, water samples were collected using cm-scale multichambered passive diffusion samplers (peepers) to span the wetland-aquifer interface over a period of 3 yr. Samples were analyzed for major cations and anions, methane, and a suite of organic acids resulting in a large dataset of over 8000 points, which was evaluated using multivariate statistics. Principal component analysis (PCA) was chosen with the purpose of exploring the sources of variation in the dataset to expose related variables and provide insight into the biogeochemical processes that control the water chemistry of the system. Factor scores computed from PCA were mapped by date and depth. Patterns observed suggest that (i) fermentation is the process controlling the greatest variability in the dataset and it peaks in May; (ii) iron and sulfate reduction were the dominant terminal electron-accepting processes in the system and were associated with fermentation but had more complex seasonal variability than fermentation; (iii) methanogenesis was also important and associated with bacterial utilization of minerals as a source of electron acceptors (e.g., barite BaSO4); and (iv) seasonal hydrological patterns (wet and dry periods) control the availability of electron acceptors through the reoxidation of reduced iron-sulfur species enhancing iron and sulfate reduction. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  12. 对人脸识别特征数据降维算法的优化%Optimization of Dimension Reduction Algorithm for Face Recognition Character Data

    Institute of Scientific and Technical Information of China (English)

    杨玉平; 向华

    2012-01-01

    在模式识别领域,人脸特征数据相对庞大,为了提取人脸主要的特征数据,提高识别系统的运行效率,对特征数据的降维是必须的操作。针对现有降维算法对识别率有较大影响的问题,本文总结了各类降维算法,提出了一种优化的降维算法。%In the field of pattern recognition,facial character data is relatively large,and therefore it is necessary to reduce the dimension of the character data in order to extract the primary facial main data and improve the efficiency of the recognition system.For the existing dimension reduction algorithm has some negative effect on the recognition rate,this article sums up various kinds of dimension reduction algorithms and brings forward a better algorithm.

  13. Coupling between Pentachlorophenol Dechlorination and Soil Redox As Revealed by Stable Carbon Isotope, Microbial Community Structure, and Biogeochemical Data.

    Science.gov (United States)

    Xu, Yan; He, Yan; Zhang, Qian; Xu, Jianming; Crowley, David

    2015-05-05

    Carbon isotopic analysis and molecular-based methods were used in conjunction with geochemical data sets to assess the dechlorination of pentachlorophenol (PCP) when coupled to biogeochemical processes in a mangrove soil having no prior history of anthropogenic contamination. The PCP underwent 96% dechlorination in soil amended with acetate, compared to 21% dehalogenation in control soil. Carbon isotope analysis of residual PCP demonstrated an obvious enrichment of 13C (εC, -3.01±0.1%). Molecular and statistical analyses demonstrated that PCP dechlorination and Fe(III) reduction were synergistically combined electron-accepting processes. Microbial community analysis further suggested that enhanced dechlorination of PCP during Fe(III) reduction was mediated by members of the multifunctional family of Geobacteraceae. In contrast, PCP significantly suppressed the growth of SO4(2-) reducers, which, in turn, facilitated the production of CH4 by diversion of electrons from SO4(2-) reduction to methanogenesis. The integrated data regarding stoichiometric alterations in this study gives direct evidence showing PCP, Fe(III), and SO4(2-) reduction, and CH4 production are coupled microbial processes during changes in soil redox.

  14. Biogeochemical drivers of microbial community convergence across actively retreating glaciers

    Energy Technology Data Exchange (ETDEWEB)

    Castle, Sarah C.; Nemergut, Diana R.; Grandy, A. Stuart; Leff, Jonathan W.; Graham, Emily B.; Hood, Eran; Schmidt, Steven K.; Wickings, Kyle; Cleveland, Cory C.

    2016-10-01

    The ecological processes that influence biogeographical patterns of microorganisms are actively debated. To investigate how such patterns emerge during ecosystem succession, we examined the biogeochemical drivers of bacterial community assembly in soils over two environmentally distinct, recently deglaciated chronosequences separated by a distance of more than 1,300 kilometers. Our results show that despite different geographic, climatic, and soil chemical and physical characteristics at the two sites, soil bacterial community structure and decomposer function converged during plant succession. In a comparative analysis, we found that microbial communities in early succession soils were compositionally distinct from a group of diverse, mature forest soils, but that the differences between successional soils and mature soils decreased from early to late stages of succession. Differences in bacterial community composition across glacial sites were largely explained by pH. However, successional patterns and community convergence across sites were more consistently related to soil organic carbon and organic matter chemistry, which appeared to be tightly coupled with bacterial community structure across both young and mature soils.

  15. [A biogeochemical model for the Gulf of Nicoya, Costa Rica].

    Science.gov (United States)

    Tabash Blanco, Farid A

    2007-03-01

    In agreement with the Broecker and Penn two-boxes model, I generated a biogeochemical balance model for the Gulf of Nicoya (Guanacaste, Costa Rica) using two nutrient reservoirs: surface water and deep water. The mixing zone was located at a depth of 20 m. There is a balance between surface waters descending to the bottom and upwelling waters that carry nutrients and other chemical elements to the surface. The main source of nitrogen (nitrate), was the outlet of the Tempisque and Tárcoles rivers. The Gulf of Nicoya is a net source of Dissolved Inorganic Nitrogen (DIN) with an availability rate of 87 x 10(3) mol day(-1) in the dry season and 3044 x 10(3) mol day(-1)in the rainy season. Dissolved Inorganic Phosphate (DIP) was estimated in 27 mol day(-1) in the dry season and 207 mol day(-1) in the rainy season. The dynamics of these biolimited nutrients, in relation to runoff seasonal variations, fits the biological processes reported for the gulf, for example, for variations in primary productivity levels, and maturity and reproduction seasons for species with short and long life cycles.

  16. Hyporheic flow and transport processes: mechanisms, models, and biogeochemical implications

    Science.gov (United States)

    Boano, Fulvio; Harvey, Judson W.; Marion, Andrea; Packman, Aaron I.; Revelli, Roberto; Ridolfi, Luca; Anders, Wörman

    2014-01-01

    Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed."

  17. Tracking evolution of urban biogeochemical cycles: salinization of fresh water

    Science.gov (United States)

    Kaushal, S.; McDowell, W. H.; Wollheim, W. M.; Duan, S.; Gorman, J. K.; Haq, S.; Hohman, S.; Smith, R. M.; Mayer, P. M.

    2014-12-01

    The built environment often changes quickly in response to human activities, thus contributing to an evolution of stream chemistry over time. Depending upon development and management strategies, these changes can result in pulses and/or long-term trends. Here, we explore patterns of evolving salinization of fresh water over time, and we evaluate the potential water quality implications of fresh water salinization. We show that there has been global salinization of freshwater across urbanizing landscapes over a century. We also show that human-accelerated weathering in watersheds and river alkalinization can further influence regional rates of salinization (in addition to anthropogenic sources such as road salts, sewage leaks, etc.). Finally, we investigate how salinization of fresh water can impact stream sediment fluxes of carbon, nutrients, and sulfate in watersheds across a land use gradient at the Baltimore Long-Term Ecological Research (LTER) site. The impacts of salinization on mobilization and uptake of carbon, nutrients, and sulfate in streams warrant further consideration in water quality management strategies. Overall, we propose that salinization can be a "universal tracer" of watershed urbanization globally with major regional consequences for drinking water and evolution of biogeochemical cycles in freshwater ecosystems.

  18. River restoration: morphological, hydrological, biogeochemical and ecological changes and challenges

    Directory of Open Access Journals (Sweden)

    M. Schirmer

    2013-08-01

    Full Text Available River restoration is essential as a means to enhance river dynamics, environmental heterogeneity and biodiversity. The underlying processes governing the dynamic changes need to be understood thoroughly to ensure that restoration projects meet their goals. In particular, we need to understand quantitatively how hydromorphological variability relates to ecosystem functioning and services, biodiversity and (groundwater quality in restored river corridors. Here, we provide a short overview on the literature and present a study of a restored river corridor in Switzerland combining physical, chemical, and biological observations with modeling. The results show complex spatial patterns of bank infiltration, habitat-type, biotic communities and biogeochemical processes. In particular, we found an increase in taxonomic and functional diversity for earthworms, testate amoebae and bacteria in the restored part of the river. This complexity is driven by river hydrology and morphodynamics, which are in turn actively coupled to riparian vegetation processes. Given this complexity and the multiple constraints on the uses and management of floodplains, a multi-disciplinary approach is needed to monitor the success of restoration measures and to make recommendations for future restoration projects.

  19. Biogeochemical controls of uranium bioavailability from the dissolved phase

    Science.gov (United States)

    Croteau, Marie-Noele; Fuller, Christopher C.; Cain, Daniel J.; Campbell, Kate M.; Aiken, George R.

    2016-01-01

    To gain insights into the risks associated with uranium (U) mining and processing, we investigated the biogeochemical controls of U bioavailability in the model freshwater speciesLymnaea stagnalis (Gastropoda). Bioavailability of dissolved U(VI) was characterized in controlled laboratory experiments over a range of water hardness, pH, and in the presence of complexing ligands in the form of dissolved natural organic matter (DOM). Results show that dissolved U is bioavailable under all the geochemical conditions tested. Uranium uptake rates follow first order kinetics over a range encompassing most environmental concentrations. Uranium uptake rates in L. stagnalis ultimately demonstrate saturation uptake kinetics when exposure concentrations exceed 100 nM, suggesting uptake via a finite number of carriers or ion channels. The lack of a relationship between U uptake rate constants and Ca uptake rates suggest that U does not exclusively use Ca membrane transporters. In general, U bioavailability decreases with increasing pH, increasing Ca and Mg concentrations, and when DOM is present. Competing ions did not affect U uptake rates. Speciation modeling that includes formation constants for U ternary complexes reveals that the aqueous concentration of dicarbonato U species (UO2(CO3)2–2) best predicts U bioavailability to L. stagnalis, challenging the free-ion activity model postulate

  20. 基于ICM拓扑优化的加工中心床身轻量化设计%Weight-reduction Design for Machining Center Bed Based on ICM Topological Optimization

    Institute of Scientific and Technical Information of China (English)

    任帅; 宋冬冬

    2014-01-01

    为实现高速卧式加工中心床身的轻量化设计,以床身的质量最小化为目标,提出了基于ICM方法的拓扑优化模型。分别对床身进行了二维、三维拓扑轻量化设计,并对设计结果进行了可制造化处理,给出了床身优化后的仿真模型。基于有限元理论对新床身进行静动态性能分析。结果表明,在新床身具有良好的静动态性能的前提下,新床身比原床身质量减少了13%,实现了加工中心床身的轻量化设计。%In order to realize weight-reduction design of high-speed horizontal machining center bed,topological optimization model based on ICM method was proposed with a view to minimize the mass of the bed. The 2D and 3D topology weight-reduction de-sign for the bed were respectively given,and manufacturability process for the design results and the simulation model of the bed after optimization were given. Static and dynamic performance analyses for the new bed were given based on finite element method (FEM). The results show that the weight of the new bed reduces 13% than the old bed in premises of the new bed with good static and dynamic performance,which can realize the weight-reduction design of the machining center bed.

  1. Carbon Capture Systems Optimal Allocation Scheme for Multi-stage Emission Reduction Planning in Power Plants%基于多阶段减排规划的发电厂碳捕集系统优化配置

    Institute of Scientific and Technical Information of China (English)

    卢志刚; 夏明昭; 张晓辉

    2011-01-01

    According to the requirements of the carbon dioxide emission reduction planning and taking full account of the progressive and uncertainty of the development of the current carbon dioxide capture and storage technology (CCS), a model of emission reduction planning in power plants with the goal to minimum general expenses was developed. By introducing technology readiness level factor and considering the future changes in power plants operation parameters, the progressive and uncertainty of the CCS technology were quantified. Emission reduction index of the carbon capture systems was decomposition by the rate of technological progress. An algorithm based on the discrete bacterial colony chemotaxis (DBCC) was used to solve this problem, the optimal allocation and investment strategy of carbon capture systems under different emission reduction scenarios was obtained by the simulation analysis on the practical example. Finally, the impact of different factors on the mitigation costs in different emission reduction scenarios was obtained by sensitivity analysis. The results demonstrate the effectiveness of the model and the optimization algorithm.%根据二氧化碳减排规划的要求,并充分考虑目前二氧化碳捕集和封存(carbon capture and storage,CCS)技术发展的阶段性与不确定性,建立以阶段综合费用最小为目标函数的发电厂减排规划模型。引入技术成熟度因子,并考虑到发电厂运行参数未来的变化,将CCS技术的阶段性与不确定因素进行量化,依据技术进步率对碳捕集系统减排指标进行分解。采用离散细菌群体趋药性算法(discrete bacterial colony chemotaxis,DBCC)进行求解,通过对实际算例的方针分析,得到系统在不同减排场景下的碳捕集系统最优配置方案与碳捕集系统投资策略。最后通过灵敏度分析得到在不同减排场景下各因素对减排成本的影响。结果证明了所提模型以及

  2. High-Resolution Biogeochemical Simulation Identifies Practical Opportunities for Bioenergy Landscape Intensification Across Diverse US Agricultural Regions

    Science.gov (United States)

    Field, J.; Adler, P. R.; Evans, S.; Paustian, K.; Marx, E.; Easter, M.

    2015-12-01

    The sustainability of biofuel expansion is strongly dependent on the environmental footprint of feedstock production, including both direct impacts within feedstock-producing areas and potential leakage effects due to disruption of existing food, feed, or fiber production. Assessing and minimizing these impacts requires novel methods compared to traditional supply chain lifecycle assessment. When properly validated and applied at appropriate spatial resolutions, biogeochemical process models are useful for simulating how the productivity and soil greenhouse gas fluxes of cultivating both conventional crops and advanced feedstock crops respond across gradients of land quality and management intensity. In this work we use the DayCent model to assess the biogeochemical impacts of agricultural residue collection, establishment of perennial grasses on marginal cropland or conservation easements, and intensification of existing cropping at high spatial resolution across several real-world case study landscapes in diverse US agricultural regions. We integrate the resulting estimates of productivity, soil carbon changes, and nitrous oxide emissions with crop production budgets and lifecycle inventories, and perform a basic optimization to generate landscape cost/GHG frontiers and determine the most practical opportunities for low-impact feedstock provisioning. The optimization is constrained to assess the minimum combined impacts of residue collection, land use change, and intensification of existing agriculture necessary for the landscape to supply a commercial-scale biorefinery while maintaining exiting food, feed, and fiber production levels. These techniques can be used to assess how different feedstock provisioning strategies perform on both economic and environmental criteria, and sensitivity of performance to environmental and land use factors. The included figure shows an example feedstock cost-GHG mitigation tradeoff frontier for a commercial-scale cellulosic

  3. Global Biogeochemical Changes at Both Ends of the Proterozoic: Insights from Phosphorites

    Science.gov (United States)

    Papineau, D.

    2010-04-01

    The striking similarities in biogeochemical evolution between the Paleo- and Neoproterozoic are discussed in light of the two oldest phosphogenic events in Earth's history and their relations to the step-wise rise of atmospheric oxygen.

  4. Final report on biogeochemical cycling of selenium in Benton Lake, Montana

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The biogeochemical cycling of selenium in Benton Lake National Wildlife Refuge, west-central Montana was very complicated. Selenium accumulation in sediment was a...

  5. Interactions of Biogeochemical Cycles in Oncoid Microbialites from Cuatro Ciénegas, Mexico

    Science.gov (United States)

    Corman, J. R.; Souza, V.; Elser, J. J.

    2010-04-01

    Modern microbialite systems may provide unique opportunities to study the feedbacks that couple or uncouple multiple biogeochemical cycles. Here we present results from a two-week manipulative ecosystem experiment using oncoid microbialites from Cuatro Ciénegas, Mexico.

  6. Molecular organic tracers of biogeochemical processes in a saline meromictic lake (Ace Lake)

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Schouten, S.; Rijpstra, W.I.C.; Kok, M.D.; Hopmans, E.C.; Summons, R.E.; Volkman, J.K.

    2001-01-01

    The chemical structures, distribution and stable carbon isotopic compositions of lipids in a sediment core taken in meromictic Ace Lake (Antarctica) were analyzed to trace past biogeochemical cycling. Biomarkers from methanogenic archaea, methanotrophic bacteria and photosynthetic green sulfur bacte

  7. Nitrous Oxide Emissions from Biofuel Crops and Parameterization in the EPIC Biogeochemical Model

    Science.gov (United States)

    This presentation describes year 1 field measurements of N2O fluxes and crop yields which are used to parameterize the EPIC biogeochemical model for the corresponding field site. Initial model simulations are also presented.

  8. A decade of physical and biogeochemical measurements in the Northern Indian Ocean.

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Sardesai, S.; Ramaiah, N.

    of the coupling between the physical and biogeochemical fields in the northern Indian Ocean over the seasonal scale have enhanced tremendously, a sustained regional observational network including repeat sections, moored arrays and drifters is needed...

  9. Nitrous Oxide Emissions from Biofuel Crops and Parameterization in the EPIC Biogeochemical Model

    Science.gov (United States)

    This presentation describes year 1 field measurements of N2O fluxes and crop yields which are used to parameterize the EPIC biogeochemical model for the corresponding field site. Initial model simulations are also presented.

  10. Thermodynamics at work - on the limits and potentials of biogeochemical processes

    Science.gov (United States)

    Peiffer, Stefan

    2017-04-01

    The preferential use of high potential electron acceptors by microorganisms has lead to the classical concept of a redox sequence with a sequential use of O2 nitrate, Fe(III), sulfate, and finally CO2 as electron acceptors for respiration (Stumm & Morgan, 1996). Christian Blodau has rigourously applied this concept to constrain the thermodynamical limits at which specific aquatic systems operate. In sediments from acidic mining lakes his analysis revealed that sulfate reducers are not competitive as long as low-crystallinity ferric oxides are available for organic matter decomposition (Blodau et al, 1998). This analysis opened up the possibility to generalize the linkage between the iron and sulphur cycle in such systems and to constrain the biogeochemical limits for remediation (e. g. Peine et al, 2000). In a similar approach, Beer & Blodau (2007) were able to demonstrate that constraints on the removal of products from acetoclastic methanogenesis in deeper peat layers are inhibiting organic matter decomposition and provide a thermodynamic argument for peat accumulation. In this contribution I will review such ideas and further refine the limits and potentials of biogeochemical reactions in terms of redox-active metastable phases (RAMPS) that are typically mixed-valent carbon-, iron-, and sulfur-containing compounds and which allow for the occurrence of a number of enigmatic reactions, e. g. limited greenhouse gas emission (CH4) under dynamic redox conditions. It is proposed that redox equivalents are generated, stored and recycled during oxidation and reduction cycles thus suppressing methanogenesis (Blodau, 2002). Such RAMPS will preferentially occur at dynamic interfaces being exposed to frequent redox cycles. The concept of RAMPS will be illustrated along the interaction between ferric (hydr)oxides and dissolved sulphide. Recent studies using modern analytical tools revealed the formation of a number of amorphous products within a short time scale (days) both

  11. Variable importance of macrofaunal functional biodiversity for biogeochemical cycling in temperate coastal sediments

    OpenAIRE

    Braeckman, U.; Yazdani Foshtomi, M.; Van Gansbeke, D.; Meysman, F.; Soetaert, K.; Vincx, M.; Vanaverbeke, J.

    2014-01-01

    Coastal marine systems are currently subject to a variety of anthropogenic and climate-change-induced pressures. An important challenge is to predict how marine sediment communities and benthic biogeochemical cycling will be affected by these ongoing changes. To this end, it is of paramount importance to first better understand the natural variability in coastal benthic biogeochemical cycling and how this is influenced by local environmental conditions and faunal biodiversity. Here, we studie...

  12. Clouds, aerosols and biogeochemical cycles. Risks of non-linear climate change

    Energy Technology Data Exchange (ETDEWEB)

    Van Ham, J.; Van Beers, R.J.; Builtjes, P.J.H.; Roemer, M.G.M. [TNO Institute of Environmental Sciences, Delft (Netherlands); Koennen, G.P. [Royal Netherlands Meteorological Institute KNMI, De Bilt (Netherlands); Oerlemans, J. [Institute for Meteorological and Atmospheric Research, University of Utrecht, Utrecht (Netherlands)

    1995-12-31

    Part of the results of an investigation into risks for climate change, which are presently not adequately covered in General Circulation Models, is described. The investigation included the interaction with biogeochemical cycles, the effects of clouds and aerosols, ice flow instability, albedo instability and modified ocean circulation. In this paper our results for clouds and aerosols and for bio-geochemical cycles are reported. 1 tab., 21 refs.

  13. Sub-hourly changes in biogeochemical properties in surface waters of Zuari estuary, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Anand, S.S.; Anju, K.J.; Mathew, D.; DileepKumar, M.

    and biogeochemical processes and consequent variability in properties. 2.2 Sampling Strategies Experiments were conducted twice; Experiment 1 during flood phase of neap tide on 13 June 2012 and Experiment 2 during ebb phase of the spring tide on 21 June 2012. 2... (Experiment 2) than the flood phase of the neap tide (Experiment 1). Higher deviations in Experiment 2 seem associated with higher turbidity of the estuarine waters than in Experiment 1. Table 2 contains the ranges of biogeochemical properties observed...

  14. Effect of Vertical Flow Exchange on Biogeochemical Processes in Hyporheic Zones

    Science.gov (United States)

    Kim, H.; Lee, S.; Shin, D.; Hyun, Y.; Lee, K.

    2008-12-01

    Biogeochemical processes in hyporheic zones are of great interest because they make the hyporheic zones highly productive and complex environments. When contaminants or polluted water pass through hyporheic zones, in particular, biogeochemical processes play an important role in removing contaminants or attenuating contamination under certain conditions. The study site, a reach of Munsan stream (Paju-si, South Korea), exhibits severe contamination of surface water by nitrate released from Water Treatment Plant (WTP) nearby. The objectives of this study are to investigate the hydrologic and biogeochemical processes at the riparian area of the site which may contribute to natural attenuation of surface water driven nitrate, and analyze the effect of vertical (hyporheic) flow exchange on the biogeochemical processes in the area. To examine hydraulic mixing or dilution processes, vertical hydraulic gradients were measured at several depth levels using minipiezometers, and then soil temperatures were measured by using i-buttons installed inside the minipiezometers. The microbial analyses by means of polymerase chain reaction (PCR)-cloning methods were also done in order to identify the denitrification process in soil samples. In addition, correlation between vertical flow exchange, temperature data, and denitrifying bacteria activity was also investigated so as to examine the effects on one another. The results showed that there were significant effects of vertical flow exchange and hyporheic soil temperature on the biogeochemical processes of the site. This study found strong support for the idea that the biogeochemical function of hyporheic zone is a predictable outcome of the interaction between microbial activity and flow exchange.

  15. Diel biogeochemical processes and their effect on the aqueous chemistry of streams: A review

    Science.gov (United States)

    Nimick, David A.; Gammons, Christopher H.; Parker, Stephen R.

    2011-01-01

    This review summarizes biogeochemical processes that operate on diel, or 24-h, time scales in streams and the changes in aqueous chemistry that are associated with these processes. Some biogeochemical processes, such as those producing diel cycles of dissolved O2 and pH, were the first to be studied, whereas processes producing diel concentration cycles of a broader spectrum of chemical species including dissolved gases, dissolved inorganic and organic carbon, trace elements, nutrients, stable isotopes, and suspended particles have received attention only more recently. Diel biogeochemical cycles are interrelated because the cyclical variations produced by one biogeochemical process commonly affect another. Thus, understanding biogeochemical cycling is essential not only for guiding collection and interpretation of water-quality data but also for geochemical and ecological studies of streams. Expanded knowledge of diel biogeochemical cycling will improve understanding of how natural aquatic environments function and thus lead to better predictions of how stream ecosystems might react to changing conditions of contaminant loading, eutrophication, climate change, drought, industrialization, development, and other factors.

  16. Poverty Reduction

    OpenAIRE

    Ortiz, Isabel

    2007-01-01

    The paper reviews poverty trends and measurements, poverty reduction in historical perspective, the poverty-inequality-growth debate, national poverty reduction strategies, criticisms of the agenda and the need for redistribution, international policies for poverty reduction, and ultimately understanding poverty at a global scale. It belongs to a series of backgrounders developed at Joseph Stiglitz's Initiative for Policy Dialogue.

  17. Silicon biogeochemical processes in a large river (Cauvery, India)

    Science.gov (United States)

    Kameswari Rajasekaran, Mangalaa; Arnaud, Dapoigny; Jean, Riotte; Sarma Vedula, V. S. S.; Nittala, S. Sarma; Sankaran, Subramanian; Gundiga Puttojirao, Gurumurthy; Keshava, Balakrishna; Cardinal, Damien

    2016-04-01

    Silicon (Si), one of the key nutrients for diatom growth in ocean, is principally released during silicate weathering on continents and then exported by rivers. Phytoplankton composition is determined by the availability of Si relative to other nutrients, mainly N and P, which fluxes in estuarine and coastal systems are affected by eutrophication due to land use and industrialization. In order to understand the biogeochemical cycle of Si and its supply to the coastal ocean, we studied a tropical monsoonal river from Southern India (Cauvery) and compare it with other large and small rivers. Cauvery is the 7th largest river in India with a basin covering 85626 sq.km. The major part of the basin (˜66%) is covered by agriculture and inhabited by more than 30 million inhabitants. There are 96 dams built across the basin. As a consequence, 80% of the historical discharge is diverted, mainly for irrigation (Meunier et al. 2015). This makes the Cauvery River a good example of current anthropogenic pressure on silicon biogeochemical cycle. We measured amorphous silica contents (ASi) and isotopic composition of dissolved silicon (δ30Si-DSi) in the Cauvery estuary, including freshwater end-member and groundwater as well as along a 670 km transect along the river course. Other Indian rivers and estuaries have also been measured, including some less impacted by anthropogenic pressure. The average Cauvery δ30Si signature just upstream the estuary is 2.21±0.15 ‰ (n=3) which is almost 1‰ heavier than the groundwater isotopic composition (1.38±0.03). The δ30Si-DSi of Cauvery water is also almost 1‰ heavier than the world river supply to the ocean estimated so far and 0.4‰ heavier than other large Indian rivers like Ganges (Frings et al 2015) and Krishna. On the other hand, the smaller watersheds (Ponnaiyar, Vellar, and Penna) adjacent to Cauvery also display heavy δ30Si-DSi. Unlike the effect of silicate weathering, the heavy isotopic compositions in the river

  18. Biogeochemical Modeling of the Second Rise of Oxygen

    Science.gov (United States)

    Smith, M. L.; Catling, D.; Claire, M.; Zahnle, K.

    2014-03-01

    The rise of atmospheric oxygen set the tempo for the evolution of complex life on Earth. Oxygen levels are thought to have increased in two broad steps: one step occurred in the Archean ~ 2.45 Ga (the Great Oxidation Event or GOE), and another step occured in the Neoproterozoic ~750-580 Ma (the Neoprotoerozoic Oxygenation Event or NOE). During the NOE, oxygen levels increased from ~1-10% of the present atmospheric level (PAL) (Holland, 2006), to ~15% PAL in the late Neoproterozoic, to ~100% PAL later in the Phanerozoic. Complex life requires O2, so this transition allowed complex life to evolve. We seek to understand what caused the NOE. To explore causes for the NOE, we build upon the biogeochemical model of Claire et al. (2006), which calculates the redox evolution of the atmosphere, ocean, biosphere, and crust in the Archean through to the early Proterozoic. In this model, the balance between oxygenconsuming and oyxgen-producing fluxes evolves over time such that at ~2.4 Ga, the rapidly acting sources of oxygen outweigh the rapidly-acting sinks. Or, in other words, at ~2.4 Ga, the flux of oxygen from organic carbon burial exceeds the sinks of oxygen from reaction with reduced volcanic and metamoprphic gases. The model is able to drive oxygen levels to 1-10% PAL in the Proterozoic; however, the evolving redox fluxes in the model cannot explain how oxygen levels pushed above 1-10% in the late Proterozoic. The authors suggest that perhaps another buffer, such as sulfur, is needed to describe Proterozoic and Phanerozoic redox evolution. Geologic proxies show that in the Proterozoic, up to 10% of the deep ocean may have been sulfidic. With this ocean chemistry, the global sulfur cycle would have worked differently than it does today. Because the sulfur and oxygen cycles interact, the oxygen concentration could have permanently changed due to an evolving sulfur cycle (in combination with evolving redox fluxes associated with other parts of the oxygen cycle and carbon

  19. Ecogenomics and potential biogeochemical impacts of globally abundant ocean viruses.

    Science.gov (United States)

    Roux, Simon; Brum, Jennifer R; Dutilh, Bas E; Sunagawa, Shinichi; Duhaime, Melissa B; Loy, Alexander; Poulos, Bonnie T; Solonenko, Natalie; Lara, Elena; Poulain, Julie; Pesant, Stéphane; Kandels-Lewis, Stefanie; Dimier, Céline; Picheral, Marc; Searson, Sarah; Cruaud, Corinne; Alberti, Adriana; Duarte, Carlos M; Gasol, Josep M; Vaqué, Dolors; Bork, Peer; Acinas, Silvia G; Wincker, Patrick; Sullivan, Matthew B

    2016-09-29

    Ocean microbes drive biogeochemical cycling on a global scale. However, this cycling is constrained by viruses that affect community composition, metabolic activity, and evolutionary trajectories. Owing to challenges with the sampling and cultivation of viruses, genome-level viral diversity remains poorly described and grossly understudied, with less than 1% of observed surface-ocean viruses known. Here we assemble complete genomes and large genomic fragments from both surface- and deep-ocean viruses sampled during the Tara Oceans and Malaspina research expeditions, and analyse the resulting 'global ocean virome' dataset to present a global map of abundant, double-stranded DNA viruses complete with genomic and ecological contexts. A total of 15,222 epipelagic and mesopelagic viral populations were identified, comprising 867 viral clusters (defined as approximately genus-level groups). This roughly triples the number of known ocean viral populations and doubles the number of candidate bacterial and archaeal virus genera, providing a near-complete sampling of epipelagic communities at both the population and viral-cluster level. We found that 38 of the 867 viral clusters were locally or globally abundant, together accounting for nearly half of the viral populations in any global ocean virome sample. While two-thirds of these clusters represent newly described viruses lacking any cultivated representative, most could be computationally linked to dominant, ecologically relevant microbial hosts. Moreover, we identified 243 viral-encoded auxiliary metabolic genes, of which only 95 were previously known. Deeper analyses of four of these auxiliary metabolic genes (dsrC, soxYZ, P-II (also known as glnB) and amoC) revealed that abundant viruses may directly manipulate sulfur and nitrogen cycling throughout the epipelagic ocean. This viral catalog and functional analyses provide a necessary foundation for the meaningful integration of viruses into ecosystem models where they

  20. Biogeochemical cycling in terrestrial ecosystems of the Caatinga Biome.

    Science.gov (United States)

    Menezes, R S C; Sampaio, E V S B; Giongo, V; Pérez-Marin, A M

    2012-08-01

    The biogeochemical cycles of C, N, P and water, the impacts of land use in the stocks and flows of these elements and how they can affect the structure and functioning of Caatinga were reviewed. About half of this biome is still covered by native secondary vegetation. Soils are deficient in nutrients, especially N and P. Average concentrations of total soil P and C in the top layer (0-20 cm) are 196 mg kg(-1) and 9.3 g kg(-1), corresponding to C stocks around 23 Mg ha(-1). Aboveground biomass of native vegetation varies from 30 to 50 Mg ha(-1), and average root biomass from 3 to 12 Mg ha(-1). Average annual productivities and biomass accumulation in different land use systems vary from 1 to 7 Mg ha(-1) year(-1). Biological atmospheric N2 fixation is estimated to vary from 3 to 11 kg N ha(-1) year-1 and 21 to 26 kg N ha(-1) year(-1) in mature and secondary Caatinga, respectively. The main processes responsible for nutrient and water losses are fire, soil erosion, runoff and harvest of crops and animal products. Projected climate changes in the future point to higher temperatures and rainfall decreases. In face of the high intrinsic variability, actions to increase sustainability should improve resilience and stability of the ecosystems. Land use systems based on perennial species, as opposed to annual species, may be more stable and resilient, thus more adequate to face future potential increases in climate variability. Long-term studies to investigate the potential of the native biodiversity or adapted exotic species to design sustainable land use systems should be encouraged.

  1. Biogeochemical indicators of elevated nitrogen deposition in semiarid Mediterranean ecosystems.

    Science.gov (United States)

    Ochoa-Hueso, Raúl; Arróniz-Crespo, María; Bowker, Matthew A; Maestre, Fernando T; Pérez-Corona, M Esther; Theobald, Mark R; Vivanco, Marta G; Manrique, Esteban

    2014-09-01

    Nitrogen (N) deposition has doubled the natural N inputs received by ecosystems through biological N fixation and is currently a global problem that is affecting the Mediterranean regions. We evaluated the existing relationships between increased atmospheric N deposition and biogeochemical indicators related to soil chemical factors and cryptogam species across semiarid central, southern, and eastern Spain. The cryptogam species studied were the biocrust-forming species Pleurochaete squarrosa (moss) and Cladonia foliacea (lichen). Sampling sites were chosen in Quercus coccifera (kermes oak) shrublands and Pinus halepensis (Aleppo pine) forests to cover a range of inorganic N deposition representative of the levels found in the Iberian Peninsula (between 4.4 and 8.1 kg N ha(-1) year(-1)). We extended the ambient N deposition gradient by including experimental plots to which N had been added for 3 years at rates of 10, 20, and 50 kg N ha(-1) year(-1). Overall, N deposition (extant plus simulated) increased soil inorganic N availability and caused soil acidification. Nitrogen deposition increased phosphomonoesterase (PME) enzyme activity and PME/nitrate reductase (NR) ratio in both species, whereas the NR activity was reduced only in the moss. Responses of PME and NR activities were attributed to an induced N to phosphorus imbalance and to N saturation, respectively. When only considering the ambient N deposition, soil organic C and N contents were positively related to N deposition, a response driven by pine forests. The PME/NR ratios of the moss were better predictors of N deposition rates than PME or NR activities alone in shrublands, whereas no correlation between N deposition and the lichen physiology was observed. We conclude that integrative physiological measurements, such as PME/NR ratios, measured on sensitive species such as P. squarrosa, can provide useful data for national-scale biomonitoring programs, whereas soil acidification and soil C and N storage

  2. Ecogenomics and biogeochemical impacts of uncultivated globally abundant ocean viruses

    KAUST Repository

    Roux, Simon

    2016-05-12

    Ocean microbes drive global-scale biogeochemical cycling, but do so under constraints imposed by viruses on host community composition, metabolism, and evolutionary trajectories. Due to sampling and cultivation challenges, genome-level viral diversity remains poorly described and grossly understudied in nature such that <1% of observed surface ocean viruses, even those that are abundant and ubiquitous, are ?known?. Here we analyze a global map of abundant, double stranded DNA (dsDNA) viruses and viral-encoded auxiliary metabolic genes (AMGs) with genomic and ecological contexts through the Global Ocean Viromes (GOV) dataset, which includes complete genomes and large genomic fragments from both surface and deep ocean viruses sampled during the Tara Oceans and Malaspina research expeditions. A total of 15,222 epi- and mesopelagic viral populations were identified that comprised 867 viral clusters (VCs, approximately genus-level groups). This roughly triples known ocean viral populations, doubles known candidate bacterial and archaeal virus genera, and near-completely samples epipelagic communities at both the population and VC level. Thirty-eight of the 867 VCs were identified as the most impactful dsDNA viral groups in the oceans, as these were locally or globally abundant and accounted together for nearly half of the viral populations in any GOV sample. Most of these were predicted in silico to infect dominant, ecologically relevant microbes, while two thirds of them represent newly described viruses that lacked any cultivated representative. Beyond these taxon-specific ecological observations, we identified 243 viral-encoded AMGs in GOV, only 95 of which were known. Deeper analyses of 4 of these AMGs revealed that abundant viruses directly manipulate sulfur and nitrogen cycling, and do so throughout the epipelagic ocean. Together these data provide a critically-needed organismal catalog and functional context to begin meaningfully integrating viruses into

  3. Subglacial (bio)geochemical weathering and the unexplored Antarctic system

    Science.gov (United States)

    Mitchell, A. C.; Christner, B. C.; Mikucki, J.; Priscu, J. C.

    2009-12-01

    Water exported from Alpine and polar glaciers is often concentrated in a range of major ions, and minor and trace elements, derived from the dissolution of subglacial rocks and minerals. The export of these species from subglacial environments to the oceans via subglacial hydrological systems appears to constitute an important global flux of biochemically essential species, such as Fe, potentially impacting upon plankton activity in the oceans and the associated consumption of CO2 on glacial-interglacial timescales. Recent studies have demonstrated the presence and activity of microorganisms in a range of subglacial environments, from Alpine glaciers, Arctic glaciers, and most recently in sub-Antarctic systems. Equally, isotopic studies at Alpine and Arctic glaciers provide evidence that microbe-mineral associations occur in subglacial environments, and account for the release and transformation of dissolved nutrients. However, the link between microbiological presence & activity, mineral weathering, ionic species transformations, and the configuration of the subglacial hydrological system, remains poorly understood. We will report on Whillans Ice Stream Subglacial Access Research Drilling (WISSARD), an NSF funded integrative study of ice sheet stability and life habitats in sub Antarctic aquatic environments. Direct sterile sampling from a subglacial Antarctic lake and grounding zone, will allow us for the first time to address these gaps in our knowledge, to determine the role of microbes on the weathering of rocks and the release and transport of nutrients in and from the unexplored sub-Antarctic environment. These data will yield seminal information on these systems and test the overarching hypothesis that active hydrological systems connect various subglacial environments and exert major control on geochemistry, metabolic and phylogenetic diversity, and biogeochemical transformations, as well as ice sheet dynamics. This will provide a basis for understanding

  4. Ecogenomics and potential biogeochemical impacts of globally abundant ocean viruses

    KAUST Repository

    Roux, Simon

    2016-09-20

    Ocean microbes drive biogeochemical cycling on a global scale. However, this cycling is constrained by viruses that affect community composition, metabolic activity, and evolutionary trajectories. Owing to challenges with the sampling and cultivation of viruses, genome-level viral diversity remains poorly described and grossly understudied, with less than 1% of observed surface-ocean viruses known. Here we assemble complete genomes and large genomic fragments from both surface-and deep-ocean viruses sampled during the Tara Oceans and Malaspina research expeditions, and analyse the resulting â global ocean virome\\' dataset to present a global map of abundant, double-stranded DNA viruses complete with genomic and ecological contexts. A total of 15,222 epipelagic and mesopelagic viral populations were identified, comprising 867 viral clusters (defined as approximately genus-level groups). This roughly triples the number of known ocean viral populations and doubles the number of candidate bacterial and archaeal virus genera, providing a near-complete sampling of epipelagic communities at both the population and viral-cluster level. We found that 38 of the 867 viral clusters were locally or globally abundant, together accounting for nearly half of the viral populations in any global ocean virome sample. While two-thirds of these clusters represent newly described viruses lacking any cultivated representative, most could be computationally linked to dominant, ecologically relevant microbial hosts. Moreover, we identified 243 viral-encoded auxiliary metabolic genes, of which only 95 were previously known. Deeper analyses of four of these auxiliary metabolic genes (dsrC, soxYZ, P-II (also known as glnB) and amoC) revealed that abundant viruses may directly manipulate sulfur and nitrogen cycling throughout the epipelagic ocean. This viral catalog and functional analyses provide a necessary foundation for the meaningful integration of viruses into ecosystem models where

  5. Ecogenomics and potential biogeochemical impacts of globally abundant ocean viruses

    Science.gov (United States)

    2016-09-01

    Ocean microbes drive biogeochemical cycling on a global scale. However, this cycling is constrained by viruses that affect community composition, metabolic activity, and evolutionary trajectories. Owing to challenges with the sampling and cultivation of viruses, genome-level viral diversity remains poorly described and grossly understudied, with less than 1% of observed surface-ocean viruses known. Here we assemble complete genomes and large genomic fragments from both surface- and deep-ocean viruses sampled during the Tara Oceans and Malaspina research expeditions, and analyse the resulting ‘global ocean virome’ dataset to present a global map of abundant, double-stranded DNA viruses complete with genomic and ecological contexts. A total of 15,222 epipelagic and mesopelagic viral populations were identified, comprising 867 viral clusters (defined as approximately genus-level groups). This roughly triples the number of known ocean viral populations and doubles the number of candidate bacterial and archaeal virus genera, providing a near-complete sampling of epipelagic communities at both the population and viral-cluster level. We found that 38 of the 867 viral clusters were locally or globally abundant, together accounting for nearly half of the viral populations in any global ocean virome sample. While two-thirds of these clusters represent newly described viruses lacking any cultivated representative, most could be computationally linked to dominant, ecologically relevant microbial hosts. Moreover, we identified 243 viral-encoded auxiliary metabolic genes, of which only 95 were previously known. Deeper analyses of four of these auxiliary metabolic genes (dsrC, soxYZ, P-II (also known as glnB) and amoC) revealed that abundant viruses may directly manipulate sulfur and nitrogen cycling throughout the epipelagic ocean. This viral catalog and functional analyses provide a necessary foundation for the meaningful integration of viruses into ecosystem models where

  6. Coupled Biogeochemical Process Evaluation for Conceptualizing Trichloroethylene Co-Metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Rick Colwell; Corey Radtke; Mark Delwiche; Deborah Newby; Lynn Petzke; Mark Conrad; Eoin Brodie; Hope Lee; Bob Starr; Dana Dettmers; Ron Crawford; Andrzej Paszczynski; Nick Bernardini; Ravi Paidisetti; Tonia Green

    2006-06-01

    Chlorinated solvent wastes (e.g., trichloroethene or TCE) often occur as diffuse subsurface plumes in complex geological environments where coupled processes must be understood in order to implement remediation strategies. Monitored natural attenuation (MNA) warrants study as a remediation technology because it minimizes worker and environment exposure to the wastes and because it costs less than other technologies. However, to be accepted MNA requires different ?lines of evidence? indicating that the wastes are effectively destroyed. We are studying the coupled biogeochemical processes that dictate the rate of TCE co-metabolism first in the medial zone (TCE concentration: 1,000 to 20,000 ?g/L) of a plume at the Idaho National Laboratory?s Test Area North (TAN) site and then at Paducah or the Savannah River Site. We will use flow-through in situ reactors (FTISR) to investigate the rate of methanotrophic co-metabolism of TCE and the coupling of the responsible biological processes with the dissolved methane flux and groundwater flow velocity. TCE co-metabolic rates at TAN are being assessed and interpreted in the context of enzyme activity, gene expression, and cellular inactivation related to intermediates of TCE co-metabolism. By determining the rate of TCE co-metabolism at different groundwater flow velocities, we will derive key modeling parameters for the computational simulations that describe the attenuation, and thereby refine such models while assessing the contribution of microbial co-metabolism relative to other natural attenuation processes. This research will strengthen our ability to forecast the viability of MNA at DOE and other sites contaminated with chlorinated hydrocarbons.

  7. Biogeochemical characteristics of nitrogen and phosphorus in Jiaozhou Bay sediments

    Institute of Scientific and Technical Information of China (English)

    LI Xuegang; SONG Jinming; YUAN Huamao; DAI Jicui; LI Ning

    2007-01-01

    Sediment samples were cored from 3 locations representing the inner bay, the outer bay and the bay mouth of Jiaozhou Bay in September 2003 to study the source and biogeochemical characteristics of nitrogen and phosphorus in the bay. The content and vertical distributions of total nitrogen (TN), total phosphorus (TP), organic nitrogen (ON), organic phosphorus (OP), inorganic nitrogen (IN), inorganic phosphorus (IP), the ratio of organic carbon and total nitrogen (OC/TN), and the ratio of total nitrogen and total phosphorus (TN/TP) in the sediments were analyzed. The results show that both TN and TP in surface sediments decrease from the inner bay to the outer bay. In general, ON occupies 50%-70% of TN and IP accounts for more than 60% of TP. In ratio of OC:TN, the nitrogen accumulated in the sediments from the inner bay and the bay mouth came mainly from terrestrial sources, and the portion of autogenetic nitrogen was 28.9% and 13.1%, respectively. However, in the outer bay, nitrogen was mainly autogenetic,accounting for 62.1% of TN, whereas phosphorus was mainly land-derived. The sedimentation fluxes of nitrogen and phosphorus varied spatially. The overall diagenesis rate of nitrogen was higher than that of phosphorus. Specifically, the diagenesis rate of OP was higher than that of IP. However, the diagenesis rate of ON was not always higher than that of IN. In species, the diagenesis rate of IN is sometimes much higher than that of the OC. In various environments, the diagenesis rate is, to some degree, affected by OC, pH, Eh, and Es.

  8. Biogeochemical cycling in terrestrial ecosystems of the Caatinga Biome

    Directory of Open Access Journals (Sweden)

    RSC Menezes

    Full Text Available The biogeochemical cycles of C, N, P and water, the impacts of land use in the stocks and flows of these elements and how they can affect the structure and functioning of Caatinga were reviewed. About half of this biome is still covered by native secondary vegetation. Soils are deficient in nutrients, especially N and P. Average concentrations of total soil P and C in the top layer (0-20 cm are 196 mg kg-1 and 9.3 g kg-1, corresponding to C stocks around 23 Mg ha-1. Aboveground biomass of native vegetation varies from 30 to 50 Mg ha-1, and average root biomass from 3 to 12 Mg ha-1. Average annual productivities and biomass accumulation in different land use systems vary from 1 to 7 Mg ha-1 year-1. Biological atmospheric N2 fixation is estimated to vary from 3 to 11 kg N ha-1 year-1and 21 to 26 kg N ha-1 year-1 in mature and secondary Caatinga, respectively. The main processes responsible for nutrient and water losses are fire, soil erosion, runoff and harvest of crops and animal products. Projected climate changes in the future point to higher temperatures and rainfall decreases. In face of the high intrinsic variability, actions to increase sustainability should improve resilience and stability of the ecosystems. Land use systems based on perennial species, as opposed to annual species, may be more stable and resilient, thus more adequate to face future potential increases in climate variability. Long-term studies to investigate the potential of the native biodiversity or adapted exotic species to design sustainable land use systems should be encouraged.

  9. 湿地生物地球化学过程研究进展%Advance in Study on the Biogeochemical Process in Wetlands

    Institute of Scientific and Technical Information of China (English)

    白军红; 邓伟; 朱颜明

    2002-01-01

    Wetlands are special ecosystems with distinctive biogeochemical circulation.Wetland soil locates where biogeochemical conversions take place,and its Eh value strongly influences the biogeochemical conversion procedure of elements. This paper analyzed the biogeochemical conversion procedure of essential elements such as C,N,P and S,the main environmental factors influencing the biogeochemical circulation in wetlands,and summarized important characters of the biogeochemical circulation in wetlands.It is concluded that controlling pollution and reinforcing conservation and management of wetlands will keep positive biogeochemical circulation in wetlands.

  10. Reduction of pollutants in painting operation and suggestion of an optimal technique for extracting titanium dioxide from paint sludge in car manufacturing industries--case study (SAIPA).

    Science.gov (United States)

    Khezri, Seyed Mostafa; Shariat, Seyed Mahmood; Tabibian, Sahar

    2012-06-01

    Paint sludge of car manufacturing industries are not disposed in landfills, since they contain hazardous materials with a high concentration of chromium, aluminum, titanium, barium, copper, Iron, magnesium, strontium, and so on. Thus, it is essential to find solutions in order to neutralize them or suggest cost-effective techniques, which are also environmentally acceptable. Because, this sludge contains considerable amounts of Ti pigments and unbaked resins, recycling these pigments--which could be used in a variety of industries such as paint factories--is an appropriate subject for further research. In this article, with the aim of identification of main pollutants in order to eliminate them and suggest a cost-effective solution to recover the sludge, a large number of tests including X-ray fluorescence spectroscopy, X ray diffraction spectroscopy, and diffusion thermal analysis are conducted to determine types and concentration of elements, and combinations of paint sludge in car manufacturing industries. As titanium dioxide (TiO₂) is widely used as the main pigment of automobile paints, an optimal technique is suggested for extracting TiO₂ with high purity percentage through adopting scientific methods such as membrane and electrolysis.

  11. Optimal Dietary and Plasma Magnesium Statuses Depend on Dietary Quality for a Reduction in the Risk of All-Cause Mortality in Older Adults.

    Science.gov (United States)

    Huang, Yi-Chen; Wahlqvist, Mark L; Kao, Mei-Ding; Wang, Jui-Lien; Lee, Meei-Shyuan

    2015-07-13

    The association between dietary or plasma magnesium (Mg) with diabetes incidence and with mortality in free-living elderly was investigated. A total of 1400 participants from the Taiwanese Nutrition Survey, aged ≥ 65 years, and diabetes-free from the 1999-2000 were assessed. The dietary intake and plasma Mg concentration were obtained through 24h dietary recall and health examination at baseline. Participants were classified by quartiles (Q) of dietary Mg or by the plasma Mg normal range (0.75-0.95 mmol/L). Dietary diversity score (DDS, range 1-6) represented the dietary quality. During 8 and 10 years, 231 incident diabetes cases and 475 deaths were identified. Cox's proportional-hazards regression was used to evaluate the association between Mg and health outcomes. The hazard ratios (95% confidence interval) for death in Q2 and Q3 of Mg intakes with DDS > 4 were 0.57 (0.44-0.74) and 0.59 (0.39-0.88), respectively, compared with the lowest intake and DDS ≤ 4 participants. Participants with normal and high plasma Mg in conjunction with high DDS had relative risks of 0.58 (0.37-0.89) and 0.46 (0.25-0.85) in mortality compared with low plasma Mg and lower DDS. Optimal dietary Mg intake and plasma Mg depend on dietary quality to reduce the mortality risk in older adults.

  12. Reduction of methanol in brewed wine by the use of atmospheric and room-temperature plasma method and the combination optimization of malt with different adjuncts.

    Science.gov (United States)

    Liang, Ming-Hua; Liang, Ying-Jie; Chai, Jiang-Yan; Zhou, Shi-Shui; Jiang, Jian-Guo

    2014-11-01

    Methanol, often generated in brewed wine, is highly toxic for human health. To decrease the methanol content of the brewed wine, atmospheric and room-temperature plasma (ARTP) was used as a new mutagenesis tool to generate a mutant of Saccharomyces cerevisiae with lower methanol content. Headspace gas chromatography was used to determine the identity and concentration of methanol with butyl acetate as internal standard in brewed wine. With 47.4% higher and 26.3% positive mutation rates were obtained, the ARTP jet exhibited a strong effect on mutation breeding of S. cerevisiae. The mutant S. cerevisiae S12 exhibited the lowest methanol content, which was decreased by 72.54% compared with that of the wild-type strain. Subsequently, the mutant S. cerevisiae S12 was used to ferment different combinations of malt and adjuncts for lower methanol content and higher alcoholic content. It was shown that the culture 6#, which was 60% malt, 20% wheat, and 20% corn, was the best combinations of malt and adjuncts, with the lowest methanol content (104.8 mg/L), and a relatively higher alcoholic content (15.3%, v/v). The optimal malt-adjunct culture 6#, treated with the glucoamylase dose of 0.04 U/mg of grain released the highest reducing sugars (201.6 mg/mL). It was indicated that the variation in reducing sugars among the combinations of malt and different adjuncts could be due to the dose of exogenous enzymes.

  13. Integrated application of river water quality modelling and cost-benefit analysis to optimize the environmental economical value based on various aquatic waste load reduction strategies

    Science.gov (United States)

    Wu, Chen-Yu; Fan, Chihhao

    2017-04-01

    improvements in BOD, SS and NH3-N were estimated as 36.2%, 27.7% and 29.2%, respectively. The net present value (i.e., economical-based environmental impact) becomes positive in the sixtieth year following the original government planning. We designed two scenarios for further comparison: (i) treatment efficiency improvement of pollution control facilities, and (ii) biogas-based power generation using livestock manure. If government budget is not a limiting factor, improving the efficiency of sewage treatment plants can make the occurrence of balance between payments and revenues (i.e., net present value in this study) three years earlier. For the biogas-based power generation scenario, if all pig farms with livestock number >2000 install the on-site power generation equipment, BOD will further improve by 9% and the time span of payback period will be shortened by 1 year. If all the manure waste from pig-farms is collected for subsequent electricity generation, the BOD river pollution index is estimated to improve to lightly-polluted category for more than half the length of Erhjen Creek. In short, water quality modelling technique not only can assess the contributions of related projects, but establish a practical pollution reduction strategy using cost-benefit analysis, which allows decision-maker to find a suitable pollution reduction plan to exhibit most benefits in river water quality.

  14. Noble metal recycling. Project 2: Optimization of discontinuous thermal processes (emission reduction). Final report; Edelmetallrecycling. Teilvorhaben 2: Weiterentwicklung der Verfahrenstechnik bei diskontinuierlichen thermischen Prozessen (Emissionsminderung). Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Baumbach, G.; Berger, R.

    2000-10-01

    A batch operated incineration process, used for the recycling of precious metals is described in the report. The development of a new combined pyrolysis/oxidation Process is the main focus of the work. This new process has several remarkable advantages compared to traditionally used techniques. The optimisation of the process with a modern fuzzy based control technique is described in detail. The emissions of the process were reduced considerably applying the new process and the innovative control technique. Furthermore the layout of several components of the new process can be reduced in the future. The developed techniques can also be applied in other thermal processes, especially batch processes. Additionally the application of catalysts for PCDD/PCDF reduction in the flue gas upstream and downstream of the filter was investigated. Whereas the catalyst performed well, as expected, downstream of the filter, no acceptable operation was possible upstream of the filter. As the reheating downstream the filter is economically not feasible the application of catalysts is not applicable for the describe process. (orig.) [German] Die Arbeit beschreibt einen diskontinuierlichen thermischen Prozess, der zur Rueckgewinnung von Edelmetallen eingesetzt wird. Der Schwerpunkt der Arbeit liegt auf der Entwicklung eines neuartigen kombinierten Pyrolyse/Oxidations-Prozesses, der gegenueber den traditionell eingesetzten Anlagen grosse Vorteile aufweist. Die Optimierung dieses Prozesses mit Hilfe modernster Fuzzy-Regelungstechnik wird detailliert beschrieben. Mit dem neuen Verfahren und den innovativen Regelungstechniken konnten die Emissionen des Prozesses merklich gesenkt werden, ohne den Energiebedarf negativ zu beeinflussen. Ausserdem koennen zukuenftige Anlagen kleiner ausgelegt werden. Die entwickelten Verfahren koennen auch auf andere thermische Prozesse uebertragen werden. Weiterhin wurde der Einsatz von Katalysatoren zur PCDD/PCDF-Minderung im Rein- und Rohgas untersucht

  15. Optimal time interval between a single course of antenatal corticosteroids and delivery for reduction of respiratory distress syndrome in preterm twins.

    Science.gov (United States)

    Kuk, Jin-Yi; An, Jung-Ju; Cha, Hyun-Hwa; Choi, Suk-Joo; Vargas, Juan E; Oh, Soo-young; Roh, Cheong-Rae; Kim, Jong-Hwa

    2013-09-01

    The objective of the study was to investigate the effect of a single course of antenatal corticosteroid (ACS) therapy on the incidence of respiratory distress syndrome (RDS) in preterm twins according to the time interval between ACS administration and delivery. We performed a retrospective cohort study of twins born between 24 and 34 weeks of gestation from November 1995 to May 2011. Subjects were grouped on the basis of the time interval between the first ACS dose and delivery: the ACS-to-delivery interval of less than 2 days (n = 166), 2-7 days (n = 114), and more than 7 days (n = 66). Pregnancy and neonatal outcomes of each group were compared with a control group of twins who were not exposed to ACS (n = 122). Multiple logistic regression analysis was used to examine the association between the ACS-to-delivery interval and the incidence of RDS after adjusting for potential confounding variables. Compared with the ACS nonexposure group, the incidence of RDS in the group with an ACS-to-delivery interval of less than 2 days was not significantly different (adjusted odds ratio [aOR], 1.089; 95% confidence interval [CI], 0.524-2.262; P = .819). RDS occurred significantly less frequently when the ACS-to-delivery interval was between 2 and 7 days (aOR, 0.419; 95% CI, 0.181-0.968; P = .042). However, there was no significant reduction in the incidence of RDS when the ACS-to-delivery interval exceeded 7 days (aOR, 2.205; 95% CI, 0.773-6.292; P = .139). In twin pregnancies, a single course of ACS treatment was associated with a decreased rate of RDS only when the ACS-to-delivery interval was between 2 and 7 days. Copyright © 2013 Mosby, Inc. All rights reserved.

  16. Optimal Dietary and Plasma Magnesium Statuses Depend on Dietary Quality for a Reduction in the Risk of All-Cause Mortality in Older Adults

    Directory of Open Access Journals (Sweden)

    Yi-Chen Huang

    2015-07-01

    Full Text Available The association between dietary or plasma magnesium (Mg with diabetes incidence and with mortality in free-living elderly was investigated. A total of 1400 participants from the Taiwanese Nutrition Survey, aged ≥ 65 years, and diabetes-free from the 1999–2000 were assessed. The dietary intake and plasma Mg concentration were obtained through 24h dietary recall and health examination at baseline. Participants were classified by quartiles (Q of dietary Mg or by the plasma Mg normal range (0.75–0.95 mmol/L. Dietary diversity score (DDS, range 1–6 represented the dietary quality. During 8 and 10 years, 231 incident diabetes cases and 475 deaths were identified. Cox’s proportional-hazards regression was used to evaluate the association between Mg and health outcomes. The hazard ratios (95% confidence interval for death in Q2 and Q3 of Mg intakes with DDS > 4 were 0.57 (0.44–0.74 and 0.59 (0.39–0.88, respectively, compared with the lowest intake and DDS ≤ 4 participants. Participants with normal and high plasma Mg in conjunction with high DDS had relative risks of 0.58 (0.37–0.89 and 0.46 (0.25–0.85 in mortality compared with low plasma Mg and lower DDS. Optimal dietary Mg intake and plasma Mg depend on dietary quality to reduce the mortality risk in older adults.

  17. Study on Toxicity Reduction and Potency Induction in Whole-cell Pertussis Vaccine by Developing a New Optimal Inactivation Condition Processed on Bordetella pertussis

    Science.gov (United States)

    Mohammadpour Dounighi, Naser; Razzaghi-Abyane, Mehdi; Nofeli, Mojtaba; Zolfagharian, Hossein; Shahcheraghi, Fereshteh

    2016-01-01

    Background Whooping cough is caused by Bordetella pertussis, and it remains a public health concern. Whole-cell pertussis vaccines have been commonly employed for expanded immunization. There is no doubt of the efficacy of whole cell pertussis vaccine, but it is necessary to improve the vaccine to decrease its toxicity. Objectives In this study, an inactivation process of dealing with pertussis bacteria is optimized in order to decrease the bacteria content in human doses of vaccines and reduce the vaccine’s toxicity. Materials and Methods The bacterial suspensions of pertussis strains 509 and 134 were divided into 21 sample parts from F1 to F21 and inactivated under different conditions. The inactivated suspensions of both strains were tested for opacity, non-viability, agglutination, purity, and sterility; the same formulation samples that passed quality tests were then pooled together. The pool of inactivated suspensions were analyzed for sterility, agglutination, opacity, specific toxicity, and potency. Results The harvest of both bacterial strains showed purity. The opacity of various samples were lost under different treatment conditions by heat from 8% to 12%, formaldehyde 6% to 8%, glutaraldehyde 6% to 8%, and thimerosal 5% to 8%. Tests on suspensions after inactivation and on pooled suspensions showed inactivation conditions not degraded agglutinins of both strains. The samples of F2, F4, F8, F12, F15, and F17 passed the toxicity test. The potency (ED50) of these samples showed following order F17 > F12 > F8 > F15, F4 > F2, and F17 revealed higher potency compared to other formulations. Conclusions It can be concluded that F17 showed desirable outcomes in the toxicity test and good immunogenicity with a low bacterial number content. Consequently, lower adverse effects and good immunogenicity are foreseeable for vaccine preparation with this method. PMID:27679704

  18. Nutrient removal using biosorption activated media: preliminary biogeochemical assessment of an innovative stormwater infiltration basin

    Science.gov (United States)

    O'Reilly, Andrew M.; Wanielista, Martin P.; Chang, Ni-Bin; Xuan, Zhemin; Harris, Willie G.

    2012-01-01

    Soil beneath a stormwater infiltration basin receiving runoff from a 22.7 ha predominantly residential watershed in central Florida, USA, was amended using biosorption activated media (BAM) to study the effectiveness of this technology in reducing inputs of nitrogen and phosphorus to groundwater. The functionalized soil amendment BAM consists of a 1.0:1.9:4.1 mixture (by volume) of tire crumb (to increase sorption capacity), silt and clay (to increase soil moisture retention), and sand (to promote sufficient infiltration), which was applied to develop a prototype stormwater infiltration basin utilizing nutrient reduction and flood control sub-basins. Comparison of nitrate/chloride (NO3-/Cl-) ratios for the shallow groundwater indicate that prior to using BAM, NO3- concentrations were substantially influenced by nitrification or variations in NO3- input. In contrast, for the prototype basin utilizing BAM, NO3-/Cl- ratios indicate minor nitrification and NO3- losses with the exception of one summer sample that indicated a 45% loss. Biogeochemical indicators (denitrifier activity derived from real-time polymerase chain reaction and variations in major ions, nutrients, dissolved and soil gases, and stable isotopes) suggest NO3- losses are primarily attributable to denitrification, whereas dissimilatory nitrate reduction to ammonium is a minor process. Denitrification was likely occurring intermittently in anoxic microsites in the unsaturated zone, which was enhanced by increased soil moisture within the BAM layer and resultant reductions in surface/subsurface oxygen exchange that produced conditions conducive to increased denitrifier activity. Concentrations of total dissolved phosphorus and orthophosphate (PO43-) were reduced by more than 70% in unsaturated zone soil water, with the largest decreases in the BAM layer where sorption was the most likely mechanism for removal. Post-BAM PO43-/Cl- ratios for shallow groundwater indicate predominantly minor increases and

  19. Including the biogeochemical impacts of deforestation increases projected warming of climate

    Science.gov (United States)

    Scott, Catherine; Monks, Sarah; Spracklen, Dominick; Arnold, Stephen; Forster, Piers; Rap, Alexandru; Carslaw, Kenneth; Chipperfield, Martyn; Reddington, Carly; Wilson, Christopher

    2016-04-01

    Forests cover almost one third of the Earth's land area and their distribution is changing as a result of human activities. The presence, and removal, of forests affects the climate in many ways, with the net climate impact of deforestation dependent upon the relative strength of these effects (Betts, 2000; Bala et al., 2007; Davin and de Noblet-Ducoudré, 2010). In addition to controlling the surface albedo and exchanging carbon dioxide (CO2) and moisture with the atmosphere, vegetation emits biogenic volatile organic compounds (BVOCs), which lead to the formation of biogenic secondary organic aerosol (SOA) and alter the oxidative capacity of the atmosphere, affecting ozone (O3) and methane (CH4) concentrations. In this work, we combine a land-surface model with a chemical transport model, a global aerosol model, and a radiative transfer model to compare several radiative impacts of idealised deforestation scenarios in the present day. We find that the simulated reduction in biogenic SOA production, due to complete global deforestation, exerts a positive combined aerosol radiative forcing (RF) of between +308.0 and +362.7 mW m-2; comprised of a direct radiative effect of between +116.5 and +165.0 mW m-2, and a first aerosol indirect effect of between +191.5 and +197.7 mW m-2. We find that the reduction in O3 exerts a negative RF of -150.7 mW m-2 and the reduction in CH4 results in a negative RF of -76.2 mWm-2. When the impacts on biogenic SOA, O3 and CH4 are combined, global deforestation exerts an overall positive RF of between +81.1 and +135.9 mW m-2 through changes to short-lived climate forcers (SLCF). Taking these additional biogeochemical impacts into account increases the net positive RF of complete global deforestation, due to changes in CO2 and surface albedo, by 7-11%. Overall, our work suggests that deforestation has a stronger warming impact on climate than previously thought. References: Bala, G. et al., 2007. Combined climate and carbon-cycle effects

  20. Data assimilation in a coupled physical-biogeochemical model of the California current system using an incremental lognormal 4-dimensional variational approach: Part 3-Assimilation in a realistic context using satellite and in situ observations

    Science.gov (United States)

    Song, Hajoon; Edwards, Christopher A.; Moore, Andrew M.; Fiechter, Jerome

    2016-10-01

    A fully coupled physical and biogeochemical ocean data assimilation system is tested in a realistic configuration of the California Current System using the Regional Ocean Modeling System. In situ measurements for sea surface temperature and salinity as well as satellite observations for temperature, sea level and chlorophyll are used for the year 2000. Initial conditions of the combined physical and biogeochemical state are adjusted at the start of each 3-day assimilation cycle. Data assimilation results in substantial reduction of root-mean-square error (RMSE) over unconstrained model output. RMSE for physical variables is slightly lower when assimilating only physical variables than when assimilating both physical variables and surface chlorophyll. Surface chlorophyll RMSE is lowest when assimilating both physical variables and surface chlorophyll. Estimates of subsurface, nitrate and chlorophyll show modest improvements over the unconstrained model run relative to independent, unassimilated in situ data. Assimilation adjustments to the biogeochemical initial conditions are investigated within different regions of the California Current System. The incremental, lognormal 4-dimensional data assimilation method tested here represents a viable approach to coupled physical biogeochemical state estimation at practical computational cost.

  1. Improved dose calculation accuracy for low energy brachytherapy by optimizing dual energy CT imaging protocols for noise reduction using sinogram affirmed iterative reconstruction.

    Science.gov (United States)

    Landry, Guillaume; Gaudreault, Mathieu; van Elmpt, Wouter; Wildberger, Joachim E; Verhaegen, Frank

    2016-03-01

    The goal of this study was to evaluate the noise reduction achievable from dual energy computed tomography (CT) imaging (DECT) using filtered backprojection (FBP) and iterative image reconstruction algorithms combined with increased imaging exposure. We evaluated the data in the context of imaging for brachytherapy dose calculation, where accurate quantification of electron density ρe and effective atomic number Zeff is beneficial. A dual source CT scanner was used to scan a phantom containing tissue mimicking inserts. DECT scans were acquired at 80 kVp/140Sn kVp (where Sn stands for tin filtration) and 100 kVp/140Sn kVp, using the same values of the CT dose index CTDIvol for both settings as a measure for the radiation imaging exposure. Four CTDIvol levels were investigated. Images were reconstructed using FBP and sinogram affirmed iterative reconstruction (SAFIRE) with strength 1,3 and 5. From DECT scans two material quantities were derived, Zeff and ρe. DECT images were used to assign material types and the amount of improperly assigned voxels was quantified for each protocol. The dosimetric impact of improperly assigned voxels was evaluated with Geant4 Monte Carlo (MC) dose calculations for an (125)I source in numerical phantoms. Standard deviations for Zeff and ρe were reduced up to a factor ∼2 when using SAFIRE with strength 5 compared to FBP. Standard deviations on Zeff and ρe as low as 0.15 and 0.006 were achieved for the muscle insert representing typical soft tissue using a CTDIvol of 40 mGy and 3mm slice thickness. Dose calculation accuracy was generally improved when using SAFIRE. Mean (maximum absolute) dose errors of up to 1.3% (21%) with FBP were reduced to less than 1% (6%) with SAFIRE at a CTDIvol of 10 mGy. Using a CTDIvol of 40mGy and SAFIRE yielded mean dose calculation errors of the order of 0.6% which was the MC dose calculation precision in this study and no error was larger than ±2.5% as opposed to errors of up to -4% with FPB. This

  2. Using an Adaptative Fuzzy-Logic System to Optimize the Performances and the Reduction of Chattering Phenomenon in the Control of Induction Motor

    Directory of Open Access Journals (Sweden)

    M. M. Krishan

    2010-01-01

    direction that allows for the design of robust controllers for uncertain non-linear dynamical systems without resorting to system model simplifications and linearization and without imposing structural conditions on system uncertainties. On the other hand, it is important to say that this approach permits to improve the performance of the controlled system only by choosing the appropriate form of the membership functions (shape, triangular and a good partionnement of the universe of discourse of the diverse variables. Finally the obtained simulation results prove that the objectives of the authors where attempt by a significant reduction of the chattering and a good robustness of the process towards parameter variation and external perturbation (load torque.

  3. Drug use practices among people who inject drugs in a context of drug market changes: Challenges for optimal coverage of harm reduction programs.

    Science.gov (United States)

    Roy, Élise; Arruda, Nelson; Leclerc, Pascale; Morissette, Carole; Blanchette, Caty; Blouin, Karine; Alary, Michel

    2017-07-01

    Until the early 2000s, people who inject drugs (PWID) in Québec had mainly been injecting powder cocaine and heroin. Since then, ethnographic studies have shown that the drug market has diversified, with crack and prescription opioids (PO) becoming increasingly available. This could have led to changes in drug use practices among PWID. The objectives of our study were to examine annual trends in injection of different drugs, crack smoking and frequent injection (FI), as well as relationships between injected drugs and FI. PWID are participants in the ongoing Québec SurvUDI surveillance system. PWID (past 6 months) were recruited in 2 urban and 6 semi-urban/rural sites. Each visit included a structured interview addressing drug use behaviours. Analyses were carried out using GEE methods. For trend analyses (2003-2014) on drugs and FI (number of injections≥upper quartile, previous month), the first annual interview was selected for PWID with multiple participations per year. Analyses on associations between FI and types of injected drugs were based on all interviews (2004-2014). Crack/cocaine and heroin injection declined significantly, with prevalence ratios (PR) per year of 0.983 [95% confidence interval (CI): 0.980-0.986] and 0.979 (95% CI: 0.969-0.990), while PO injection [PR=1.052 (1.045-1.059)], crack smoking [PR=1.006 (1.001-1.012)], and FI (≥120 injections, previous month) significantly increased [PR=1.015 (1.004-1.026)]. Compared to PWID who injected crack/cocaine±other drugs, the proportion of PWID reporting FI was higher among those who injected PO+heroin/speedball, crack/cocaine or other drugs (adjusted PR 2.29; 95% CI: 2.07-2.53) or PO only (aPR 1.72; 95%CI: 1.47-2.01). Changes that have occurred in the drug market are reflected in PWID's practices. The high frequency of injection observed among PO injectors is of particular concern. Drug market variations are a challenge for health authorities responsible for harm reduction programs. Copyright

  4. Consistent Reduction in Periprocedural Myocardial Infarction With Cangrelor as Assessed by Multiple Definitions: Findings From CHAMPION PHOENIX (Cangrelor Versus Standard Therapy to Achieve Optimal Management of Platelet Inhibition).

    Science.gov (United States)

    Cavender, Matthew A; Bhatt, Deepak L; Stone, Gregg W; White, Harvey D; Steg, Ph Gabriel; Gibson, C Michael; Hamm, Christian W; Price, Matthew J; Leonardi, Sergio; Prats, Jayne; Deliargyris, Efthymios N; Mahaffey, Kenneth W; Harrington, Robert A

    2016-09-06

    Cangrelor is an intravenous P2Y12 inhibitor approved to reduce periprocedural ischemic events in patients undergoing percutaneous coronary intervention not pretreated with a P2Y12 inhibitor. A total of 11 145 patients were randomized to cangrelor or clopidogrel in the CHAMPION PHOENIX trial (Cangrelor versus Standard Therapy to Achieve Optimal Management of Platelet Inhibition). We explored the effects of cangrelor on myocardial infarction (MI) using different definitions and performed sensitivity analyses on the primary end point of the trial. A total of 462 patients (4.2%) undergoing percutaneous coronary intervention had an MI as defined by the second universal definition. The majority of these MIs (n=433, 93.7%) were type 4a. Treatment with cangrelor reduced the incidence of MI at 48 hours (3.8% versus 4.7%; odds ratio [OR], 0.80; 95% confidence interval [CI], 0.67-0.97; P=0.02). When the Society of Coronary Angiography and Intervention definition of periprocedural MI was applied to potential ischemic events, there were fewer total MIs (n=134); however, the effects of cangrelor on MI remained significant (OR, 0.65; 95% CI, 0.46-0.92; P=0.01). Similar effects were seen in the evaluation of the effects of cangrelor on MIs with peak creatinine kinase-MB ≥10 times the upper limit of normal (OR, 0.64; 95% CI, 0.45-0.91) and those with peak creatinine kinase-MB ≥10 times the upper limit of normal, ischemic symptoms, or ECG changes (OR, 0.63; 95% CI, 0.48-0.84). MIs defined by any of these definitions were associated with increased risk of death at 30 days. Treatment with cangrelor reduced the composite end point of death, MI (Society of Coronary Angiography and Intervention definition), ischemia-driven revascularization, or Academic Research Consortium definite stent thrombosis (1.4% versus 2.1%; OR, 0.69; 95% CI, 0.51-0.92). MI in patients undergoing percutaneous coronary intervention, regardless of definition, remains associated with increased risk of death

  5. Weight-reduction Optimization Design for Horizontal Gantry Milling Machine Based on ANSYS%基于ANSYS的卧式龙门铣床轻量化设计

    Institute of Scientific and Technical Information of China (English)

    吴珊; 肖琪聃; 孙金磊; 刘林超

    2015-01-01

    利用ANSYS有限元软件对TK6363型卧式龙门铣床立柱进行了仿真优化分析,计算结果表明铣床立柱结构设计不够合理,导致铣床用材量增多,制造成本升高。通过优化立柱内部加筋板布局形式,实现了在保证加工精度条件下的最优用材量,产品性价比得到大幅提升。同时计算分析了改进前后铣床立柱的振动特性,改进前后铣床立柱基本振动形式没有发生明显改变,改进后立柱各阶频率均有提高。实践表明,该研究不仅解决了工程实际问题,而且为卧式龙门铣床立柱的结构设计提供有益参考。%The simulation analysis on vertical pillar of BP-1100/700 horizontal gantry milling machine was accomplished by the finite element analysis software ANSYS. The calculation results show that the original structure is unreasonable in design, which is the key reason for increased material amount and costs. Through adjusting the structure of vertical pillar, which make the optimal amount of material used under the conditions of guarantee precision and also the price performance be improved. Meanwhile, the free vibration of the original structure and redesigned structure were analyzed. The modal analysis showed that their princi-pal mode of vibration has no obvious change, and after redesigned, frequency of vertical pillar increased sig-nificantly. This research solves a practical problem and also provides a reference for vertical pillar of hori-zontal gantry milling machin.

  6. Biogeochemical study on mud-volcano sediments from the Kumano forearc basin, Japan

    Science.gov (United States)

    Ijiri, A.; Toki, T.; Yamaguchi, Y. T.; Kawagucci, S.; Hattori, S.; Morono, Y.; Lever, M. A.; Yoshida, N.; Tsunogai, U.; Nakamura, K.; Takai, K.; Ashi, J.; Inagaki, F.

    2011-12-01

    We investigated microbial communities and biogeochemical processes in mud-volcano subsurface sediments down to 20 meters from the summit, obtained from the Kumano forearc basin in the Nankai Trough during the CK09-01 D/V Chikyu training cruise in 2009. The cored sediments contained several methane hydrates. Chemical characteristics of pore fluid indicated that the fluid in the mud volcano was supplied from the accretionary prism beneath the forearc sediments probably through faults. The cored sediments contained relatively low population of microbial cells (sediment depth (from -41 to -22%), synchronous to the increase of δ13CDIC. The significant isotopic fractionation between DIC and acetate (54.0±6.9%) indicates that the principal process producing acetate is homo-acetogenesis via the reductive acetyl-CoA pathway. Radioactive tracer experiments exhibited relatively high activities of homo-acetogenesis (14-34,900 pmol/cm3/day) compared to that of hydrogenotrophic methanogenesis (0.6-128 pmol/cm3/day). In ordinary marine sediments, homo-acetogenesis from H2 and CO2 is thermodynamically inhibited because H2 concentrations are maintained at low levels less than several nM. However, the homo-acetogenesis was thermodynamically favorable in the cored sediments because of the high concentration of H2 (>560nM). These results showed that homo-acetogenesis is dominant in the sediments around the summit of the mud volcano, while active hydrogenotrophic methanogenesis has been occurred in a deeper depth, and most portion of methane formed methane hydrates was supplied from the deep active methanogenic zone.

  7. Biogeochemical processes and buffering capacity concurrently affect acidification in a seasonally hypoxic coastal marine basin

    Science.gov (United States)

    Hagens, M.; Slomp, C. P.; Meysman, F. J. R.; Seitaj, D.; Harlay, J.; Borges, A. V.; Middelburg, J. J.

    2015-03-01

    Coastal areas are impacted by multiple natural and anthropogenic processes and experience stronger pH fluctuations than the open ocean. These variations can weaken or intensify the ocean acidification signal induced by increasing atmospheric pCO2. The development of eutrophication-induced hypoxia intensifies coastal acidification, since the CO2 produced during respiration decreases the buffering capacity in any hypoxic bottom water. To assess the combined ecosystem impacts of acidification and hypoxia, we quantified the seasonal variation in pH and oxygen dynamics in the water column of a seasonally stratified coastal basin (Lake Grevelingen, the Netherlands). Monthly water-column chemistry measurements were complemented with estimates of primary production and respiration using O2 light-dark incubations, in addition to sediment-water fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TA). The resulting data set was used to set up a proton budget on a seasonal scale. Temperature-induced seasonal stratification combined with a high community respiration was responsible for the depletion of oxygen in the bottom water in summer. The surface water showed strong seasonal variation in process rates (primary production, CO2 air-sea exchange), but relatively small seasonal pH fluctuations (0.46 units on the total hydrogen ion scale). In contrast, the bottom water showed less seasonality in biogeochemical rates (respiration, sediment-water exchange), but stronger pH fluctuations (0.60 units). This marked difference in pH dynamics could be attributed to a substantial reduction in the acid-base buffering capacity of the hypoxic bottom water in the summer period. Our results highlight the importance of acid-base buffering in the pH dynamics of coastal systems and illustrate the increasing vulnerability of hypoxic, CO2-rich waters to any acidifying process.

  8. Biogeochemical processes and buffering capacity concurrently affect acidification in a seasonally hypoxic coastal marine basin

    Directory of Open Access Journals (Sweden)

    M. Hagens

    2014-11-01

    Full Text Available Coastal areas are impacted by multiple natural and anthropogenic processes and experience stronger pH fluctuations than the open ocean. These variations can weaken or intensify the ocean acidification signal induced by increasing atmospheric pCO2. The development of eutrophication-induced hypoxia intensifies coastal acidification, since the CO2 produced during respiration decreases the buffering capacity of the hypoxic bottom water. To assess the combined ecosystem impacts of acidification and hypoxia, we quantified the seasonal variation in pH and oxygen dynamics in the water column of a seasonally stratified coastal basin (Lake Grevelingen, the Netherlands. Monthly water column chemistry measurements were complemented with estimates of primary production and respiration using O2 light-dark incubations, in addition to sediment-water fluxes of dissolved inorganic carbon (DIC and total alkalinity (TA. The resulting dataset was used to set up a proton budget on a seasonal scale. Temperature-induced seasonal stratification combined with a high community respiration was responsible for the depletion of oxygen in the bottom water in summer. The surface water showed strong seasonal variation in process rates (primary production, CO2 air–sea exchange, but relatively small seasonal pH fluctuations (0.46 units on the total hydrogen ion scale. In contrast, the bottom water showed less seasonality in biogeochemical rates (respiration, sediment–water exchange, but stronger pH fluctuations (0.60 units. This marked difference in pH dynamics could be attributed to a substantial reduction in the acid-base buffering capacity of the hypoxic bottom water in the summer period. Our results highlight the importance of acid-base buffering in the pH dynamics of coastal systems and illustrate the increasing vulnerability of hypoxic, CO2-rich waters to any acidifying process.

  9. Soil engineering in vivo: harnessing natural biogeochemical systems for sustainable, multi-functional engineering solutions.

    Science.gov (United States)

    DeJong, Jason T; Soga, Kenichi; Banwart, Steven A; Whalley, W Richard; Ginn, Timothy R; Nelson, Douglas C; Mortensen, Brina M; Martinez, Brian C; Barkouki, Tammer

    2011-01-06

    Carbon sequestration, infrastructure rehabilitation, brownfields clean-up, hazardous waste disposal, water resources protection and global warming-these twenty-first century challenges can neither be solved by the high-energy consumptive practices that hallmark industry today, nor by minor tweaking or optimization of these processes. A more radical, holistic approach is required to develop the sustainable solutions society needs. Most of the above challenges occur within, are supported on, are enabled by or grown from soil. Soil, contrary to conventional civil engineering thought, is a living system host to multiple simultaneous processes. It is proposed herein that 'soil engineering in vivo', wherein the natural capacity of soil as a living ecosystem is used to provide multiple solutions simultaneously, may provide new, innovative, sustainable solutions to some of these great challenges of the twenty-first century. This requires a multi-disciplinary perspective that embraces the science of biology, chemistry and physics and applies this knowledge to provide multi-functional civil and environmental engineering designs for the soil environment. For example, can native soil bacterial species moderate the carbonate cycle in soils to simultaneously solidify liquefiable soil, immobilize reactive heavy metals and sequester carbon-effectively providing civil engineering functionality while clarifying the ground water and removing carbon from the atmosphere? Exploration of these ideas has begun in earnest in recent years. This paper explores the potential, challenges and opportunities of this new field, and highlights one biogeochemical function of soil that has shown promise and is developing rapidly as a new technology. The example is used to propose a generalized approach in which the potential of this new field can be fully realized.

  10. The changing role of dust in biogeochemical cycling

    Science.gov (United States)

    Neff, J. C.; Reynolds, R. L.; Farmer, G. L.; Reheis, M.

    2007-12-01

    Dust emission and deposition have the potential to deplete and enrich ecosystems of mineral resources essential to life. In many parts of the world, and particularly in semi-arid settings, wind erosion of soils and the subsequent long-distance transport and deposition of mineral aerosols play a basic role in soil composition and processes, including the production of essential plant nutrients through weathering. Although the long-term role of dust in the development of soils is reasonably well understood, the effects of recent dust emission and deposition on ecosystems are not. Recent work on ecosystems around the world has highlighted the fundamental importance of contemporary wind erosion and dust deposition in biogeochemical cycling. In the western U.S., studies of Sr and Nd isotopes, elemental concentrations, and magnetic properties elucidate the role of dust in recent soil development and soil loss by wind erosion related to land-use change. In the arid landscapes in and around Canyonlands National Park (Utah), these techniques provide insight into the development of soils in stable settings where human activities have been minimal but the loss of soil in areas affected by grazing and recreational activities. In stable settings of the central Colorado Plateau (Utah), dust deposition is responsible for a large proportion (as much as 20 percent) of surface soil mass and elemental content. In contrast, wind erosion is responsible for large losses of nutrients and surface soil of nearby, closely similar geomorphic settings disturbed by human activity. In the San Juan Mountains (Colorado) downwind of the Colorado Plateau, Nd and Sr isotopes in dust and lake sediments provide evidence for large increases in dust deposition during the 19th and 20th century compared to records from the middle to late Holocene. The recent enhancement in dust deposition is also responsible for increased loading of many elements, including essential nutrients that may influence

  11. Key biogeochemical factors affecting soil carbon storage in Posidonia meadows

    KAUST Repository

    Serrano, Oscar

    2016-08-15

    Biotic and abiotic factors influence the accumulation of organic carbon (C-org) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of Corg. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2-4 m depth) accumulated 3- to 4-fold higher C-org stocks (averaging 6.3 kg C-org m(-2) at 3- to 4-fold higher rates (12.8 gC(org) m(-2) yr(-1) ) compared to meadows closer to the deep limits of distribution (at 6-8 m depth; 1.8 kg C-org m(-2) and 3.6 g C-org m(-2) yr(-1) . In shallower meadows, C-org stocks were mostly derived from seagrass detritus (88% in average) compared to meadows closer to the deep limit of distribution (45% on average). In addition, soil accumulation rates and fine-grained sediment content (< 0.125 mm) in shallower meadows (2.0 mm yr(-1) and 9 %, respectively) were approximately 2-fold higher than in deeper meadows (1.2 mm yr(-1) and 5 %, respectively). The C-org stocks and accumulation rates accumulated over the last 500 years in bare sediments (0.6 kg C-org m(-2) and 1.2 g C-org m(-2) yr(-1)were 3- to 11-fold lower than in P. sinuosa meadows, while fine-grained sediment content (1 %) and seagrass detritus contribution to the Corg pool (20 %) were 8- and 3-fold lower than in Posidonia meadows, respectively. The patterns found support the hypothesis that Corg storage in seagrass soils is influenced by interactions of biological (e.g., meadow productivity, cover and density), chemical (e.g., recalcitrance of Corg stocks) and physical (e.g., hydrodynamic energy and soil accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats.

  12. Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

    Science.gov (United States)

    Campbell, Kate M.; Gallegos, Tanya J.; Landa, Edward R.

    2015-01-01

    Natural uranium (U) occurs as a mixture of three radioactive isotopes: 238U, 235U, and 234U. Only 235U is fissionable and makes up about 0.7% of natural U, while 238U is overwhelmingly the most abundant at greater than 99% of the total mass of U. Prior to the 1940s, U was predominantly used as a coloring agent, and U-bearing ores were mined mainly for their radium (Ra) and/or vanadium (V) content; the bulk of the U was discarded with the tailings (Finch et al., 1972). Once nuclear fission was discovered, the economic importance of U increased greatly. The mining and milling of U-bearing ores is the first step in the nuclear fuel cycle, and the contact of residual waste with natural water is a potential source of contamination of U and associated elements to the environment. Uranium is mined by three basic methods: surface (open pit), underground, and solution mining (in situ leaching or in situ recovery), depending on the deposit grade, size, location, geology and economic considerations (Abdelouas, 2006). Solid wastes at U mill tailings (UMT) sites can include both standard tailings (i.e., leached ore rock residues) and solids generated on site by waste treatment processes. The latter can include sludge or “mud” from neutralization of acidic mine/mill effluents, containing Fe and a range of coprecipitated constituents, or barium sulfate precipitates that selectively remove Ra (e.g., Carvalho et al., 2007). In this chapter, we review the hydrometallurgical processes by which U is extracted from ore, the biogeochemical processes that can affect the fate and transport of U and associated elements in the environment, and possible remediation strategies for site closure and aquifer restoration.This paper represents the fourth in a series of review papers from the U.S. Geological Survey (USGS) on geochemical aspects of UMT management that span more than three decades. The first paper (Landa, 1980) in this series is a primer on the nature of tailings and radionuclide

  13. Biogeochemical features of aquatic plants in the Selenga River delta

    Science.gov (United States)

    Shinkareva, Galina; Lychagin, Mikhail

    2014-05-01

    The Selenga River system provides more than a half of the Lake Baikal total inflow. The river collects a significant amount of pollutants (e.g. heavy metals) from the whole basin. These substances are partially deposited within the Selenga delta, and partially are transported further to the lake. A generous amount of aquatic plants grow in the delta area according to its favorable conditions. This vegetation works as a specific biofilter. It accumulates suspended particles and sorbs some heavy metals from the water. The study aimed to reveal the species of macrophytes which could be mostly important for biomonitoring according to their chemical composition. The field campaign took place in the Selenga River delta in July-August of 2011 (high water period) and in June of 2012 (low water period). 14 species of aquatic plants were collected: water starwort Callitriche hermaphroditica, small yellow pond lily Nuphar pumila, pondweeds Potamogeton crispus, P. pectinatus, P. friesii, broadleaf cattail Typha latifolia, hornwort or coontail Ceratophyllum demersum, arrowhead Sagittaria natans, flowering rush (or grass rush) Butomus umbellatus, reed Phragmites australis, parrot's feather Myriophyllum spicatum, the common mare's tail Hippuris vulgaris, Batrachium trichophyllum, canadian waterweed Elodea canadensis. The samples were dried, grinded up and digested in a mixture of HNO3 and H2O2. The chemical composition of the plant material was defined using ICP-MS and ICP-AES methods. Concentrations of Fe, Mn, Cr, Ni, Cu, B, Zn, V, Co, As, Mo, Pb, and U were considered. The study revealed that Potamogeton pectinatus and Myriophyllum spicatum concentrate elements during both high and low water periods. Conversely the Butomus umbellatus and Phragmites australis contain small amount of heavy metals. The reed as true grasses usually accumulates fewer amounts of elements than other macrophytes. To compare biogeochemical specialization of different species we suggest to use

  14. Multifactorial biogeochemical monitoring of linden alley in Moscow

    Science.gov (United States)

    Ermakov, Vadim; Khushvakhtova, Sabsbakhor; Tyutikov, Sergey; Danilova, Valentina; Roca, Núria; Bech, Jaume

    2015-04-01

    The ecological and biogeochemical assessment of the linden alley within the Kosygin Street was conducted by means of an integrated comparative study of soils, their chemical composition and morphological parameters of leaf linden. For this purpose 5 points were tested within the linden alley and 5 other points outside the highway. In soils, water extract of soil, leaf linden the content of Cu, Pb, Mn, Fe, Cd, Zn, As, Ni, Co Mo, Cr and Se were determined by AAS and spectrofluorimetric method [1]. Macrocomponents (Ca, Mg, K, Na, P, sulphates, chlorides), pH and total mineralization of water soil extract were measured by generally accepted methods. Thio-containing compounds in the leaves were determined by HPLC-NAM spectrofluorometry [2]. On level content of trace elements the soils of "contaminated" points different from background more high concentrations of lead, manganese, iron, selenium, strontium and low level of zinc. Leaf of linden from contaminated sites characterized by an increase of lead, copper, iron, zinc, arsenic, chromium, and a sharp decrease in the level of manganese and strontium. Analysis of the aqueous extracts of the soil showed a slight decrease in the pH value in the "control" points and lower content of calcium, magnesium, potassium, sodium and total mineralization of the water soil extract. The phytochelatins test in the leaves of linden was weakly effective and the degree of asymmetry of leaf lamina too. The most differences between the variants were marked by the degree of pathology leaves (chlorosis and necrosis) and the content of pigments (chlorophyll and carotene). The data obtained reflect the impact of the application of de-icing salts and automobile emissions. References 1. Ermakov V.V., Danilova V.N., Khyshvakhtova S.D. Application of HPLC-NAM spectrofluorimtry to determination of sulfur-containing compounds in the environmental objects// Science of the biosphere: Innovation. Moscow State University by M.V. Lomonosov, 2014. P. 10

  15. Past and present of sediment and carbon biogeochemical cycling models

    Directory of Open Access Journals (Sweden)

    F. T. Mackenzie

    2004-01-01

    Full Text Available The global carbon cycle is part of the much more extensive sedimentary cycle that involves large masses of carbon in the Earth's inner and outer spheres. Studies of the carbon cycle generally followed a progression in knowledge of the natural biological, then chemical, and finally geological processes involved, culminating in a more or less integrated picture of the biogeochemical carbon cycle by the 1920s. However, knowledge of the ocean's carbon cycle behavior has only within the last few decades progressed to a stage where meaningful discussion of carbon processes on an annual to millennial time scale can take place. In geologically older and pre-industrial time, the ocean was generally a net source of CO2 emissions to the atmosphere owing to the mineralization of land-derived organic matter in addition to that produced in situ and to the process of CaCO3 precipitation. Due to rising atmospheric CO2 concentrations because of fossil fuel combustion and land use changes, the direction of the air-sea CO2 flux has reversed, leading to the ocean as a whole being a net sink of anthropogenic CO2. The present thickness of the surface ocean layer, where part of the anthropogenic CO2 emissions are stored, is estimated as of the or