DEFF Research Database (Denmark)
Chomchoei, Roongrat; Miró, Manuel; Hansen, Elo Harald
2005-01-01
An automated sequential injection (SI) system incorporating a dual-conical microcolumn is proposed as a versatile approach for the accommodation of both single and sequential extraction schemes for metal fractionation of solid samples of environmental concern. Coupled to flame atomic absorption...
Directory of Open Access Journals (Sweden)
Kari Heiskanen
2012-10-01
Full Text Available In this research article the sustainability of different practices to collect the metal fraction of household waste in the Helsinki metropolitan area, Finland is examined. The study is carried out by calculating and comparing the greenhouse gas reduction potential of optional practices for collecting the metal fraction of household waste in the Helsinki metropolitan area, Finland. In order to locate the greenhouse gas reduction potential of the separate collection of the metallic fraction of municipal solid waste (MSW collected from residential sources, a comparative carbon footprint analysis using Life Cycle Assessment (LCA on six different waste management scenarios is carried out. The modeled system consisted of a waste collection system, transportation, and different waste management alternatives, including on-site separation, separation at the waste management facility as well as metallurgical recovery of separated scrap. The results show that, in terms of greenhouse gas emissions, separate collection and recycling of the metallic fraction of solid MSW at residential properties is the preferable option compared to a scenario with no source sorting and incineration of everything. According to this research scenario where the metal fraction of solid household waste was not source-separated or collected separately have clearly higher greenhouse gas emissions compared to all the other scenarios with separate collection for metals. In addition, metal recycling by regional collection points has considerably lower greenhouse gas emission potential than metal recycling by collection directly from residential properties.
Process scheme simulation of gases and liquid fraction fractionation
International Nuclear Information System (INIS)
Rikalovska, Tatjana; Markovska, Liljana; Meshko, Vera
1999-01-01
Computer programs based on the models of process equipment are used in process development, equipment design and technology operation. Flowsheet programs has become the major tools which are used in process design and modernization of the existing processes of chemical technology. The flowsheet programs are used to examine the process, and different alternatives of each process. The simulations have been made for the process of gas recovery of gas. and liquid fractions in OKTA-Skopje by using the process simulator UNIOPT. Simulation of existing scheme has been made progressively by including the model of equipment. In this way the required database is formed for the simulation and study of different alternatives of this process. The complete design of the distillation column for separation of propane and butane has been made by DISTIL. The results obtained by simulation agree very well with the data of the real process in OKTA Crude Oil Refinery in Skopje. (Author)
Assessment of heavy metal removal technologies for biowaste by physico-chemical fractionation
Veeken, A.H.M.; Hamelers, H.V.M.
2003-01-01
In the Netherlands, the heavy metal content of biowaste-compost frequently exceeds the legal standards for heavy metals. In order to assess heavy metal removal technologies, a physico-chemical fractionation scheme was developed to gain insight into the distribution of heavy metals (Cd, Cu, Pb and
Mobile heavy metal fractions in soils
International Nuclear Information System (INIS)
Horak, O.; Kamel, A.A.; Ecker, S.; Benetka, E.; Rebler, R.; Lummerstorfer, E.; Kandeler, E.
1994-01-01
A long term outdoor experiment was conducted in plastic containers (50 litres) with three soils, contaminated by increasing concentrations of zinc, copper, nickel, cadmium and vanadium. The aim of the study was to investigate the influence of heavy metal contamination on soil microbial processes as well as the accumulation of heavy metals in plants. Spring barley, followed by winter endive were grown as experimental crops in a first vegetation period, while spring wheat was grown during the second year. The soil microbial activities, indicated by arylsulfatase, dehydrogenase, and substrate-induced respiration, decreased with increasing heavy metal contamination. Significant correlations were observed between the inhibition of soil microorganisms and the easily mobilizable heavy metal fractions of soils, extracted by a solution of 1 M ammoniumacetate at pH = 7. The heavy metal accumulation in vegetative and generative parts of the crop plants also showed a good agreement with mobilizable soil fractions. The results of the experiment indicate, that the extraction with ammoniumacetate can be used as a reference method for determination of tolerable heavy metal concentrations in soils. (authors)
Universal block diagram based modeling and simulation schemes for fractional-order control systems.
Bai, Lu; Xue, Dingyü
2017-05-08
Universal block diagram based schemes are proposed for modeling and simulating the fractional-order control systems in this paper. A fractional operator block in Simulink is designed to evaluate the fractional-order derivative and integral. Based on the block, the fractional-order control systems with zero initial conditions can be modeled conveniently. For modeling the system with nonzero initial conditions, the auxiliary signal is constructed in the compensation scheme. Since the compensation scheme is very complicated, therefore the integrator chain scheme is further proposed to simplify the modeling procedures. The accuracy and effectiveness of the schemes are assessed in the examples, the computation results testify the block diagram scheme is efficient for all Caputo fractional-order ordinary differential equations (FODEs) of any complexity, including the implicit Caputo FODEs. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
Radiation therapy of malignant melanomas: an evaluation of clinically used fractionation schemes
International Nuclear Information System (INIS)
Strauss, A.; Dritschilo, A.; Nathanson, L.; Piro, A.J.
1981-01-01
To assess the importance of radiation dose fraction size in the treatment of malignant melanomas, the records of 48 patients (83 sites) treated at Tufts-New England Medical Center from 1971 to 1979 have been retrospectively reviewed. During this period, the dose fractionation schemes evolved from standard fraction size to large-dose techniques. Radiation fraction size was observed to be the major factor in the clinical response of melanoma. Fractions of 600-800 rad resulted in the best overall response (80%). The rapid fractionation scheme of 800-400-400 rad on successive days resulted in intermediate response (58%) and may be useful for the palliative treatment of selected patients
Metal fractionation of atmospheric aerosols via sequential chemical extraction: a review
Energy Technology Data Exchange (ETDEWEB)
Smichowski, Patricia; Gomez, Dario [Unidad de Actividad Quimica, Comision Nacional de Energia Atomica, San Martin (Argentina); Polla, Griselda [Unidad de Actividad Fisica, Comision Nacional de Energia Atomica, San Martin (Argentina)
2005-01-01
This review surveys schemes used to sequentially chemically fractionate metals and metalloids present in airborne particulate matter. It focuses mainly on sequential chemical fractionation schemes published over the last 15 years. These schemes have been classified into five main categories: (1) based on Tessier's procedure, (2) based on Chester's procedure, (3) based on Zatka's procedure, (4) based on BCR procedure, and (5) other procedures. The operational characteristics as well as the state of the art in metal fractionation of airborne particulate matter, fly ashes and workroom aerosols, in terms of applications, optimizations and innovations, are also described. Many references to other works in this area are provided. (orig.)
SOLVING FRACTIONAL-ORDER COMPETITIVE LOTKA-VOLTERRA MODEL BY NSFD SCHEMES
Directory of Open Access Journals (Sweden)
S.ZIBAEI
2016-12-01
Full Text Available In this paper, we introduce fractional-order into a model competitive Lotka- Volterra prey-predator system. We will discuss the stability analysis of this fractional system. The non-standard nite difference (NSFD scheme is implemented to study the dynamic behaviors in the fractional-order Lotka-Volterra system. Proposed non-standard numerical scheme is compared with the forward Euler and fourth order Runge-Kutta methods. Numerical results show that the NSFD approach is easy and accurate for implementing when applied to fractional-order Lotka-Volterra model.
A recursion relation for coefficients of fractional parentage in the seniority scheme
International Nuclear Information System (INIS)
Evans, T.
1985-01-01
A recursion relations for coefficients as fractional parentage in the seniority scheme are discussed. Determinated dependence of recursion relations from the particle number permit to evaluate matrix elements of creation and annihilation operators for fermions or bosons. 10 refs. (author)
New Orbital Hybridization Schemes for Metal Hydrides-Keeping p ...
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 8. New Orbital Hybridization Schemes for Metal Hydrides - Keeping p Orbitals out of the Picture. J Chandrasekhar. Research News ... J Chandrasekhar1. Department of Organic Chemistry, Indian Institute of Science, Bangalore 560012, India ...
Radiation therapy of malignant melanomas: an evaluation of clinically used fractionation schemes
International Nuclear Information System (INIS)
Strauss, A.; Dritschilo, A.; Nathanson, L.; Piro, A.J.
1981-01-01
To assess the importance of radiation dose fraction size in the treatment of malignant melanomas, the records of 48 patients (83 sites) treated at Tufts-New England Medical Center from 1971 to 1979 have been retrospectively reviewed. During this period, the dose fractionation schemes evolved from standard fraction size to large-dose techniques. Radiation fraction size was observed to be the major factor in the clinical response of melanoma. Fractions of 600 to 800 rad resulted in the best overall response (80%). The rapid fractionation scheme of 800 to 400 to 400 rad on successive days resulted in intermediate response (58%) and may be useful for the palliative treatment of selected patients
International Nuclear Information System (INIS)
Lwegbue, C. M.A.; Emuh, F.N.; Isirimah, N.O.; Egun, A.C.
2007-01-01
Speciation of heavy metals in soils determines the availability for metals for plant uptake and potential for contamination of groundwater following application of composts to agricultural lands. Methods used to characterize heavy metals in solid phase of composts and compost amended soils include physical fractionation and chemical extraction. Chemical extraction schemes are most frequently used approach to fractionate trace metals in soils, sewage sludge and composts. Several variations exist in the sequential extraction procedures. These variations include reagent types, strength, volume and extraction time. A main drawback shared by all sequential extraction schemes is that the procedures themselves are complex and time consuming. This setback has been overcome by the use of ultrasound accelerated extraction which reduce the extraction time for the entire extraction steps to about 90 minutes allowing composting process to be monitored more frequently which help to provide detailed understanding of the partitioning behaviour of heavy metals. Inspite of the variability the sequential extraction schemes, they all aimed at correlating each fraction with the mobility and plant availability of each metal. Several studies have shown that phase association of heavy metal in composts include water-soluble, exchangeable, precipitated as discrete phases, co-precipitate in metal oxides and adsorbed or complexed by organic ligands and residual forms. The phase association and solubility of metals changes over composting time thereby altering metal availability. It is apparent that the positive effects of resulting from compost application far outweigh the negative effect, but more research is needed on a wide range of municipal solid waste compost with more precise determination of the fate of municipal solid waste compost applied trace metals in the environment. (author)
Fractionation, characterization and speciation of heavy metals in ...
African Journals Online (AJOL)
Speciation of heavy metals in soils determines the availability for metals for plant uptake and potential for contamination of groundwater following application of composts to agricultural lands. Methods used to characterize heavy metals in solid phase of composts and compost amended soils include physical fractionation ...
The effective delayed neutron fraction for bare-metal criticals
International Nuclear Information System (INIS)
Pearlstein, S.
1999-01-01
Given sufficient material, a large number of actinides could be used to form bare-metal criticals. The effective delayed neutron fraction for a bare critical comprised of a fissile material is comparable with the absolute delayed neutron fraction. The effective delayed neutron fraction for a bare critical composed of a fissionable material is reduced by factors of 2 to 10 when compared with the absolute delayed neutron fraction. When the effective delayed neutron fraction is small, the difference between delayed and prompt criticality is small, and extreme caution must be used in critical assemblies of these materials. This study uses an approximate but realistic model to survey the actinide region to compare effective delayed neutron fractions with absolute delayed neutron fractions
Metal fractionation in sludge from sewage UASB treatment.
Braga, A F M; Zaiat, M; Silva, G H R; Fermoso, F G
2017-05-15
This study evaluates the trace metal composition and fractionation in sludge samples from anaerobic sewage treatment plants from six cities in Brazil. Ten metals were evaluated: Ni, Mn, Se, Co, Fe, Zn, K, Cu, Pb and Cr. Specific methanogenic activity of the sludge was also evaluated using acetic acid as the substrate. Among the essential trace metals for anaerobic digestion, Se, Zn, Ni and Fe were found at a high percentage in the organic matter/sulfide fraction in all sludge samples analyzed. These metals are less available for microorganisms than other metals, i.e., Co and K, which were present in significant amounts in the exchangeable and carbonate fractions. Cu is not typically reported as an essential metal but as a possible inhibitor. One of the samples showed a total Cu concentration close to the maximal amount allowed for reuse as fertilizer. Among the non-essential trace metals, Pb was present in all sludge samples at similar low concentrations and was primarily present in the residual fraction, demonstrating very low availability. Cr was found at low concentrations in all sludge samples, except for the sludge from STP5; interestingly, this sludge presented the lowest specific methanogenic activity, indicating possible Cr toxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.
Semi solid metal processing: The fraction solid dilemma
International Nuclear Information System (INIS)
Nafisi, S.; Emadi, D.; Ghomashchi, R.
2009-01-01
One of the most challenging aspects in semi solid metal (SSM) processing is to determine the actual volume fraction of the solid at the processing temperature. The fraction has great impact on the SSM slurry viscosity and the subsequent filling of the mold in the casting stage. Three methods, namely quantitative metallography, thermodynamic calculation, and thermal analysis are employed to investigate and clarify the contradictory open literature reports about the real value of the volume fraction of primary particles. It is reported that the discrepancies between the results obtained by different methods are caused mainly by variations in cooling rates and by coarsening of the primaries during the quenching process
Semi solid metal processing: The fraction solid dilemma
Energy Technology Data Exchange (ETDEWEB)
Nafisi, S. [EVRAZ Inc. NA 100 Armour Road, Regina, SK, S4P 3C7 (Canada)], E-mail: Shahrooz.Nafisi@evrazincna.com; Emadi, D. [CEPG, CanmetENERGY, Natural Resources Canada, Ottawa, ON, K1A 1M1 (Canada); Ghomashchi, R. [Advanced Materials and Processing Research Institute, Suite 122, A7-1390 Major MacKenzie, ON, L4S 0A1 (Canada)
2009-05-15
One of the most challenging aspects in semi solid metal (SSM) processing is to determine the actual volume fraction of the solid at the processing temperature. The fraction has great impact on the SSM slurry viscosity and the subsequent filling of the mold in the casting stage. Three methods, namely quantitative metallography, thermodynamic calculation, and thermal analysis are employed to investigate and clarify the contradictory open literature reports about the real value of the volume fraction of primary particles. It is reported that the discrepancies between the results obtained by different methods are caused mainly by variations in cooling rates and by coarsening of the primaries during the quenching process.
Belazi, Akram; Abd El-Latif, Ahmed A.; Diaconu, Adrian-Viorel; Rhouma, Rhouma; Belghith, Safya
2017-01-01
In this paper, a new chaos-based partial image encryption scheme based on Substitution-boxes (S-box) constructed by chaotic system and Linear Fractional Transform (LFT) is proposed. It encrypts only the requisite parts of the sensitive information in Lifting-Wavelet Transform (LWT) frequency domain based on hybrid of chaotic maps and a new S-box. In the proposed encryption scheme, the characteristics of confusion and diffusion are accomplished in three phases: block permutation, substitution, and diffusion. Then, we used dynamic keys instead of fixed keys used in other approaches, to control the encryption process and make any attack impossible. The new S-box was constructed by mixing of chaotic map and LFT to insure the high confidentiality in the inner encryption of the proposed approach. In addition, the hybrid compound of S-box and chaotic systems strengthened the whole encryption performance and enlarged the key space required to resist the brute force attacks. Extensive experiments were conducted to evaluate the security and efficiency of the proposed approach. In comparison with previous schemes, the proposed cryptosystem scheme showed high performances and great potential for prominent prevalence in cryptographic applications.
International Nuclear Information System (INIS)
Woody, Neil M.; Videtic, Gregory M.M.; Stephans, Kevin L.; Djemil, Toufik; Kim, Yongbok; Xia Ping
2012-01-01
Purpose: Recent studies with two fractionation schemes predicted that the volume of chest wall receiving >30 Gy (V30) correlated with chest wall pain after stereotactic body radiation therapy (SBRT) to the lung. This study developed a predictive model of chest wall pain incorporating radiobiologic effects, using clinical data from four distinct SBRT fractionation schemes. Methods and Materials: 102 SBRT patients were treated with four different fractionations: 60 Gy in three fractions, 50 Gy in five fractions, 48 Gy in four fractions, and 50 Gy in 10 fractions. To account for radiobiologic effects, a modified equivalent uniform dose (mEUD) model calculated the dose to the chest wall with volume weighting. For comparison, V30 and maximum point dose were also reported. Using univariable logistic regression, the association of radiation dose and clinical variables with chest wall pain was assessed by uncertainty coefficient (U) and C statistic (C) of receiver operator curve. The significant associations from the univariable model were verified with a multivariable model. Results: 106 lesions in 102 patients with a mean age of 72 were included, with a mean of 25.5 (range, 12–55) months of follow-up. Twenty patients reported chest wall pain at a mean time of 8.1 (95% confidence interval, 6.3–9.8) months after treatment. The mEUD models, V30, and maximum point dose were significant predictors of chest wall pain (p < 0.0005). mEUD improved prediction of chest wall pain compared with V30 (C = 0.79 vs. 0.77 and U = 0.16 vs. 0.11). The mEUD with moderate weighting (a = 5) better predicted chest wall pain than did mEUD without weighting (a = 1) (C = 0.79 vs. 0.77 and U = 0.16 vs. 0.14). Body mass index (BMI) was significantly associated with chest wall pain (p = 0.008). On multivariable analysis, mEUD and BMI remained significant predictors of chest wall pain (p = 0.0003 and 0.03, respectively). Conclusion: mEUD with moderate weighting better predicted chest wall pain
Derivation of mean dose tolerances for new fractionation schemes and treatment modalities
Perkó, Zoltán; Bortfeld, Thomas; Hong, Theodore; Wolfgang, John; Unkelbach, Jan
2018-02-01
Avoiding toxicities in radiotherapy requires the knowledge of tolerable organ doses. For new, experimental fractionation schemes (e.g. hypofractionation) these are typically derived from traditional schedules using the biologically effective dose (BED) model. In this report we investigate the difficulties of establishing mean dose tolerances that arise since the mean BED depends on the entire spatial dose distribution, rather than on the dose level alone. A formula has been derived to establish mean physical dose constraints such that they are mean BED equivalent to a reference treatment scheme. This formula constitutes a modified BED equation where the influence of the spatial dose distribution is summarized in a single parameter, the dose shape factor. To quantify effects we analyzed 24 liver cancer patients for whom both proton and photon IMRT treatment plans were available. The results show that the standard BED equation—neglecting the spatial dose distribution—can overestimate mean dose tolerances for hypofractionated treatments by up to 20%. The shape difference between photon and proton dose distributions can cause 30–40% differences in mean physical dose for plans having identical mean BEDs. Converting hypofractionated, 5/15-fraction proton doses to mean BED equivalent photon doses in traditional 35-fraction regimens resulted in up to 10 Gy higher doses than applying the standard BED formula. The dose shape effect should be accounted for to avoid overestimation of mean dose tolerances, particularly when estimating constraints for hypofractionated regimens. Additionally, tolerances established for one treatment modality cannot necessarily be applied to other modalities with drastically different dose distributions, such as proton therapy. Last, protons may only allow marginal (5–10%) dose escalation if a fraction-size adjusted organ mean dose is constraining instead of a physical dose.
Fractionation of heavy metals and assessment of contamination of the sediments of Lake Titicaca.
Cáceres Choque, Luis Fernando; Ramos Ramos, Oswaldo E; Valdez Castro, Sulema N; Choque Aspiazu, Rigoberto R; Choque Mamani, Rocío G; Fernández Alcazar, Samuel G; Sracek, Ondra; Bhattacharya, Prosun
2013-12-01
Chemical weathering is one of the major geochemical processes that control the mobilization of heavy metals. The present study provides the first report on heavy metal fractionation in sediments (8-156 m) of Lake Titicaca (3,820 m a.s.l.), which is shared by the Republic of Peru and the Plurinational State of Bolivia. Both contents of total Cu, Fe, Ni, Co, Mn, Cd, Pb, and Zn and also the fractionation of these heavy metals associated with four different fractions have been determined following the BCR scheme. The principal component analysis suggests that Co, Ni, and Cd can be attributed to natural sources related to the mineralized geological formations. Moreover, the sources of Cu, Fe, and Mn are effluents and wastes generated from mining activities, while Pb and Zn also suggest that their common source is associated to mining activities. According to the Risk Assessment Code, there is a moderate to high risk related to Zn, Pb, Cd, Mn, Co, and Ni mobilization and/or remobilization from the bottom sediment to the water column. Furthermore, the Geoaccumulation Index and the Enrichment Factor reveal that Zn, Pb, and Cd are enriched in the sediments. The results suggest that the effluents from various traditional mining waste sites in both countries are the main source of heavy metal contamination in the sediments of Lake Titicaca.
New Approach for Fractioning Metal Compounds Studies in Soils
Minkina, Tatiana; Motuzova, Galina; Mandzhieva, Saglara; Bauer, Tatiana; Burachevskaya, Marina; Sushkova, Svetlana; Nevidomskaya, Dina; Kalinitchenko, Valeriy
2016-04-01
A combined approach for fractioning metal compounds in soils on the basis of sequential (Tessier, 1979) and parallel extractions (1 N NH4Ac, pH 8; 1% EDTA in NH4Ac; and 1N HCl) is proposed. Metal compounds in sequential and parallel extracts are grouped according to the strength of their bonds with soil components. A given group includes metal compounds with similar strengths of bonds and, hence, with similar migration capacities. The groups of firmly and loosely bound metal compounds can be distinguished. This approach has been used to assess the group composition of Zn, Cu, and Pb compounds in an ordinary chernozem and its changes upon the soil contamination with metals. Contamination of an ordinary chernozem from Rostov oblast with heavy metals caused a disturbance of the natural ratios between the metal compounds. In the natural soil, firmly bound metals predominate (88-95%of the total content), which is mainly caused by the fixation of metals in lattices of silicate minerals (56-83%of the total content). The mobility of the metals in the natural soil is low (5-12%) and is mainly related to metal compounds loosely bound with the soil carbonates. Upon the soil contamination with metals (application rates of 100-300 mg/kg), the content of all the metal compounds increases, but the ratio between them shifts towards a higher portion of the potentially mobile metal compounds (up to 30-40% of the bulk contents of the metals). Organic substances and non-silicate Fe, Al, and Mn minerals become the main carriers of the firmly and loosely bound metals. The strengths of their bonds with Cu, Pb, and Zn differ. Lead in the studied chernozems is mainly fixed in a loosely bound form with organic matter, whereas copper and zinc are fixed both by the organic matter and by the non-silicate Fe, Al, and Mn compounds. Firm fixation of the applied Cu and Pb is mainly ensured by the soil organic matter and non-silicate minerals, whereas firm fixation of Zn is mainly due to non
Fractionation and mobility of metals in bauxite red mud.
Rubinos, David A; Barral, María Teresa
2013-11-01
Red mud (RM) is a strongly alkaline residue generated in enormous amounts worldwide from bauxite refining using the Bayer chemical process. RM is composed mainly of Fe, Ti and Al oxides and hydroxides, but it also contains an array of trace metals and metalloids at different concentrations. The purpose of this paper is to assess the potential mobility of metals in RM, with special emphasis on pH effect. The 'operational' distribution and leachability of metals within/from RM was studied by applying a sequential extraction procedure (SEP) and several leaching tests (rapid titration, equilibration acidification, batch leaching with acetic acid and also the toxicity characteristics leaching procedure (TCLP) and the DIN 38414-S4 procedures, used as reference methods) carried out at different pH, solid/liquid ratio, extraction period and type of acid (HCl or acetic acid). Chemical analysis showed that, in addition to the major metals Fe, Al and Ti, RM contains several trace metals, some of them (Cr, Cu and Ni) in concentrations exceeding the regulatory limits. SEP showed that a majority of the metals in the RM (between the 32.2±8.5 for Cd and 95.3±0.4% for Ni) were found in the residual fraction, suggesting that they are not readily mobile under normal environmental conditions. Leaching tests performed at different pH showed that a significant fraction of the metals is mobilised from RM only under very strong acid conditions (pH<2), whereas Al is released in considerable amounts at pH<5.3. Among the trace metals, Cr requires special attention because of its relative high concentration in RM and the higher concentrations of this metal mobilised at low pH. The leaching tests using acetic acid showed that the standard TCLP largely underestimates the release of trace metals from RM, and therefore it is not advisable to evaluate the actual potential leaching of trace metals from this residue.
Dynamic flow-through approaches for metal fractionation in environmentally relevant solid samples
DEFF Research Database (Denmark)
Miró, Manuel; Hansen, Elo Harald; Chomchoei, Roongrat
2005-01-01
In the recent decades, batchwise equilibrium-based single or sequential extraction schemes have been consolidated as analytical tools for fractionation analyses to assess the ecotoxicological significance of metal ions in solid environmental samples. However, taking into account that naturally...... generations of flow-injection analysis. Special attention is also paid to a novel, robust, non-invasive approach for on-site continuous sampling of soil solutions, capitalizing on flow-through microdialysis, which presents itself as an appealing complementary approach to the conventional lysimeter experiments....... In addition, a critical comparison between the time-resolved analytical information provided by these novel dynamic extraction procedures and that of the traditional schemes is given and thoroughly discussed in the bulk of the text....
Ullah, Asmat; Chen, Wen; Khan, Mushtaq Ahmad
2017-07-01
This paper introduces a fractional order total variation (FOTV) based model with three different weights in the fractional order derivative definition for multiplicative noise removal purpose. The fractional-order Euler Lagrange equation which is a highly non-linear partial differential equation (PDE) is obtained by the minimization of the energy functional for image restoration. Two numerical schemes namely an iterative scheme based on the dual theory and majorization- minimization algorithm (MMA) are used. To improve the restoration results, we opt for an adaptive parameter selection procedure for the proposed model by applying the trial and error method. We report numerical simulations which show the validity and state of the art performance of the fractional-order model in visual improvement as well as an increase in the peak signal to noise ratio comparing to corresponding methods. Numerical experiments also demonstrate that MMAbased methodology is slightly better than that of an iterative scheme.
International Nuclear Information System (INIS)
Zhang Li-Min; Sun Ke-Hui; Liu Wen-Hao; He Shao-Bo
2017-01-01
In this paper, Adomian decomposition method (ADM) with high accuracy and fast convergence is introduced to solve the fractional-order piecewise-linear (PWL) hyperchaotic system. Based on the obtained hyperchaotic sequences, a novel color image encryption algorithm is proposed by employing a hybrid model of bidirectional circular permutation and DNA masking. In this scheme, the pixel positions of image are scrambled by circular permutation, and the pixel values are substituted by DNA sequence operations. In the DNA sequence operations, addition and substraction operations are performed according to traditional addition and subtraction in the binary, and two rounds of addition rules are used to encrypt the pixel values. The simulation results and security analysis show that the hyperchaotic map is suitable for image encryption, and the proposed encryption algorithm has good encryption effect and strong key sensitivity. It can resist brute-force attack, statistical attack, differential attack, known-plaintext, and chosen-plaintext attacks. (paper)
Energy Technology Data Exchange (ETDEWEB)
Estrada-Ruiz, R.H., E-mail: rhestrada@itsaltillo.edu.mx; Flores-Campos, R., E-mail: rcampos@itsaltillo.edu.mx; Gámez-Altamirano, H.A., E-mail: hgamez@itsaltillo.edu.mx; Velarde-Sánchez, E.J., E-mail: ejvelarde@itsaltillo.edu.mx
2016-07-05
Highlights: • Small sizes of particles are required in order to separate the different fractions. • Inverse flotation process is an efficient green technology to separate fractions. • Superficial air velocity is the main variable in the inverse flotation process. • Inverse flotation is a green process because the pulṕs pH is 7.0 during the test. - Abstract: The generation of electrical and electronic waste is increasing day by day; recycling is attractive because of the metallic fraction containing these. Nevertheless, conventional techniques are highly polluting. The comminution of the printed circuit boards followed by an inverse flotation process is a clean technique that allows one to separate the metallic fraction from the non-metallic fraction. It was found that particle size and superficial air velocity are the main variables in the separation of the different fractions. In this way an efficient separation is achieved by avoiding the environmental contamination coupled with the possible utilization of the different fractions obtained.
International Nuclear Information System (INIS)
Angstmann, C.N.; Donnelly, I.C.; Henry, B.I.; Jacobs, B.A.; Langlands, T.A.M.; Nichols, J.A.
2016-01-01
We have introduced a new explicit numerical method, based on a discrete stochastic process, for solving a class of fractional partial differential equations that model reaction subdiffusion. The scheme is derived from the master equations for the evolution of the probability density of a sum of discrete time random walks. We show that the diffusion limit of the master equations recovers the fractional partial differential equation of interest. This limiting procedure guarantees the consistency of the numerical scheme. The positivity of the solution and stability results are simply obtained, provided that the underlying process is well posed. We also show that the method can be applied to standard reaction–diffusion equations. This work highlights the broader applicability of using discrete stochastic processes to provide numerical schemes for partial differential equations, including fractional partial differential equations.
A new color image encryption scheme using CML and a fractional-order chaotic system.
Directory of Open Access Journals (Sweden)
Xiangjun Wu
Full Text Available The chaos-based image cryptosystems have been widely investigated in recent years to provide real-time encryption and transmission. In this paper, a novel color image encryption algorithm by using coupled-map lattices (CML and a fractional-order chaotic system is proposed to enhance the security and robustness of the encryption algorithms with a permutation-diffusion structure. To make the encryption procedure more confusing and complex, an image division-shuffling process is put forward, where the plain-image is first divided into four sub-images, and then the position of the pixels in the whole image is shuffled. In order to generate initial conditions and parameters of two chaotic systems, a 280-bit long external secret key is employed. The key space analysis, various statistical analysis, information entropy analysis, differential analysis and key sensitivity analysis are introduced to test the security of the new image encryption algorithm. The cryptosystem speed is analyzed and tested as well. Experimental results confirm that, in comparison to other image encryption schemes, the new algorithm has higher security and is fast for practical image encryption. Moreover, an extensive tolerance analysis of some common image processing operations such as noise adding, cropping, JPEG compression, rotation, brightening and darkening, has been performed on the proposed image encryption technique. Corresponding results reveal that the proposed image encryption method has good robustness against some image processing operations and geometric attacks.
Metallic elements fractionation in municipal solid waste incineration residues
Kowalski, Piotr R.; Kasina, Monika; Michalik, Marek
2016-04-01
Municipal solid waste incineration (MSWI) residues are represented by three main materials: bottom ash, fly ash and air pollution control (APC) residues. Among them ˜80 wt% is bottom ash. All of that materials are products of high temperature (>1000° C) treatment of waste. Incineration process allows to obtain significant reduction of waste mass (up to 70%) and volume (up to 90%) what is commonly used in waste management to reduce the amount need to be landfilled or managed in other way. Incineration promote accumulation non-combustible fraction of waste, which part are metallic elements. That type of concentration is object of concerns about the incineration residues impact on the environment and also gives the possibility of attempts to recover them. Metallic elements are not equally distributed among the materials. Several factors influence the process: melting points, volatility and place and forms of metallic occurrence in the incinerated waste. To investigate metallic elements distribution in MSWI residues samples from one of the biggest MSW incineration plant in Poland were collected in 2015. Chemical analysis with emphasis on the metallic elements content were performed using inductively coupled plasma optical emission (ICP-OES) and mass spectrometry (ICP-MS). The bottom ash was a SiO2-CaO-Al2O3-Fe2O3-Na2O rich material, whereas fly ash and APC residues were mostly composed of CaO and SiO2. All of the materials were rich in amorphous phase occurring together with various, mostly silicate crystalline phases. In a mass of bottom ash 11 wt% were metallic elements but also in ashes 8.5 wt% (fly ash) and ˜4.5 wt% (APC residues) of them were present. Among the metallic elements equal distribution between bottom and fly ash was observed for Al (˜3.85 wt%), Mn (770 ppm) and Ni (˜65 ppm). In bottom ash Fe (5.5 wt%), Cr (590 ppm) and Cu (1250 ppm) were concentrated. These values in comparison to fly ash were 5-fold higher for Fe, 3-fold for Cu and 1.5-fold for
Dynamic Flow-through Methods for Metal Fractionation in Environmental Solid Samples
DEFF Research Database (Denmark)
Miró, Manuel; Hansen, Elo Harald; Petersen, Roongrat
Accummulation of metal ions in different compartments of the biosphere and their possible mobilization under changing environmental conditions induce a pertubation of the ecosystem and may cause adverse health effects. Nowadays, it is widely recognized that the information on total content...... to the state-of-the-art and fundamental principles of automated, miniaturized strategies for on-line fractionation studies based on the concepts of stirring chambers, rotating coiled columns and packed microcartridges, mostly exploiting the attractive features of the first and second generations of flow...... availability; (2) Simplification of the overall procedure (from days to hours); (3) Automation of the extraction procedure and detection; (4) Minimization of risks of sample contamination; (5) Easy manipulation of reagents via Sequential Injection schemes; (6) Ability to implement a multitude of operational...
An Efficient Implicit FEM Scheme for Fractional-in-Space Reaction-Diffusion Equations
Burrage, Kevin
2012-01-01
Fractional differential equations are becoming increasingly used as a modelling tool for processes associated with anomalous diffusion or spatial heterogeneity. However, the presence of a fractional differential operator causes memory (time fractional) or nonlocality (space fractional) issues that impose a number of computational constraints. In this paper we develop efficient, scalable techniques for solving fractional-in-space reaction diffusion equations using the finite element method on both structured and unstructured grids via robust techniques for computing the fractional power of a matrix times a vector. Our approach is show-cased by solving the fractional Fisher and fractional Allen-Cahn reaction-diffusion equations in two and three spatial dimensions, and analyzing the speed of the traveling wave and size of the interface in terms of the fractional power of the underlying Laplacian operator. © 2012 Society for Industrial and Applied Mathematics.
Availability and bio-accessibility of metals in the clay fraction of urban soils of Sevilla.
Madrid, F; Díaz-Barrientos, E; Madrid, L
2008-12-01
The availability of Cd, Cr, Cu, Ni, Mn, Pb and Zn present in the finest size particles of urban soils is studied by comparing the concentrations in the clay fraction with those extracted from the whole soil by either single-extraction or sequential extraction method. Many metals are preferentially present in the finest particles as compared to coarser fractions. This is true for most metals studied, except Mn and, perhaps, Cd. Those metals present in the clay fraction are often in easily bio-accessible forms, especially Cu, Pb and Zn. The results suggest that bio-accessible forms of these three metals are distributed among the three sequential fractions, and even the fraction considered as 'residual' is also bio-accessible to a significant extent. The statistical analysis shows some distinctions among metals that are compared to the 'urban', 'natural', or intermediate behaviour of the various metals as proposed earlier in the literature.
Directory of Open Access Journals (Sweden)
Sekson Sirisubtawee
2017-01-01
Full Text Available We apply new modified recursion schemes obtained by the Adomian decomposition method (ADM to analytically solve specific types of two-point boundary value problems for nonlinear fractional order ordinary and partial differential equations. The new modified recursion schemes, which sometimes utilize the technique of Duan’s convergence parameter, are derived using the Duan-Rach modified ADM. The Duan-Rach modified ADM employs all of the given boundary conditions to compute the remaining unknown constants of integration, which are then embedded in the integral solution form before constructing recursion schemes for the solution components. New modified recursion schemes obtained by the method are generated in order to analytically solve nonlinear fractional order boundary value problems with a variety of two-point boundary conditions such as Robin and separated boundary conditions. Some numerical examples of such problems are demonstrated graphically. In addition, the maximal errors (MEn or the error remainder functions (ERn(x of each problem are calculated.
International Nuclear Information System (INIS)
Gaebler, H.E.; Bahr, A.; Mieke, B.
1999-01-01
An isotope dilution technique using enriched stable isotopes is applied to determine the interchangeable heavy-metal fraction in soils. Metals in two soil samples are extracted at constant pH, with water, NH 4 NO 3 , and EDTA. A spike of enriched stable isotopes is added to the suspension of sample and eluant at the beginning of the extraction. The heavy-metal fraction which exchanges with the added spike during the extraction is called the interchangeable fraction. The extractable heavy-metal fractions are obtained from the heavy-metal concentrations in the eluates. Isotope ratios and concentrations are determined by HR-ICP-MS. The isotope dilution technique described enables both the extractable and the interchangeable heavy-metal fractions to be determined in the same experiment. The combination of both results gives additional information on elemental availability under different conditions that cannot be obtained by analyzing the extractable heavy-metal fractions alone. It is demonstrated that in some cases different eluants just shift the distribution of the interchangeable fraction of an element between the solid and liquid phases (e.g., Pb and Cd in a topsoil sample) while the amount of the interchangeable fraction itself remains constant. For other elements, as Ni, Zn, and Cr, the use of different eluants (different pH, complexing agents) sometimes enlarges the interchangeable fraction. (orig.)
DEFF Research Database (Denmark)
Greeley, Jeffrey Philip; Nørskov, Jens Kehlet
2005-01-01
A simple scheme for the estimation of oxygen binding energies on transition metal surface alloys is presented. It is shown that a d-band center model of the alloy surfaces is a convenient and appropriate basis for this scheme; variations in chemical composition, strain effects, and ligand effects...... are all incorporated into the binding energy analysis through this parameter. With few exceptions, the agreement of the results from the simple model with full DFT calculations on hundreds of binary surface alloys is remarkable. The scheme should therefore provide a fast and effective method...... for the estimation of oxygen binding energies on a wide variety of transition metal alloys. (c) 2005 Elsevier B.V. All rights reserved....
International Nuclear Information System (INIS)
Ma Lijun; Sahgal, Arjun; Descovich, Martina; Cho, Y.-B.; Chuang, Cynthia; Huang, Kim; Laperriere, Normand J.; Shrieve, Dennis C.; Larson, David A.
2010-01-01
Purpose: To investigate whether dose fall-off characteristics would be significantly different among intracranial radiosurgery modalities and the influence of these characteristics on fractionation schemes in terms of normal tissue sparing. Methods and Materials: An analytic model was developed to measure dose fall-off characteristics near the target independent of treatment modalities. Variations in the peripheral dose fall-off characteristics were then examined and compared for intracranial tumors treated with Gamma Knife, Cyberknife, or Novalis LINAC-based system. Equivalent uniform biologic effective dose (EUBED) for the normal brain tissue was calculated. Functional dependence of the normal brain EUBED on varying numbers of fractions (1 to 30) was studied for the three modalities. Results: The derived model fitted remarkably well for all the cases (R 2 > 0.99). No statistically significant differences in the dose fall-off relationships were found between the three modalities. Based on the extent of variations in the dose fall-off curves, normal brain EUBED was found to decrease with increasing number of fractions for the targets, with α/β ranging from 10 to 20. This decrease was most pronounced for hypofractionated treatments with fewer than 10 fractions. Additionally, EUBED was found to increase slightly with increasing number of fractions for targets with α/β ranging from 2 to 5. Conclusion: Nearly identical dose fall-off characteristics were found for the Gamma Knife, Cyberknife, and Novalis systems. Based on EUBED calculations, normal brain sparing was found to favor hypofractionated treatments for fast-growing tumors with α/β ranging from 10 to 20 and single fraction treatment for abnormal tissues with low α/β values such as α/β = 2.
The relation between heavy metals distribution and particle size fractions in some egyptian soils
Directory of Open Access Journals (Sweden)
Monier Morad Wahba
Full Text Available Soil as a part of the environment receives pollutants from all types of human activities. Heavy metals originating from various organic waste sources and industrial activities accumulate in the soil surface, and their fate depends not only on the types and amounts of waste applied, but on soil properties. Furthermore, soils differ in their retention power for various heavy or trace elements. Twelve soil samples were selected from different sites irrigated with industrial and sewage wastes at Helwan city (Cairo Governorate in the north and El-Saff (Giza Governorate in the south. Separation of clay, silt and sand fractions were carried out. Chemical analyses of trace elements in the form of total and available contents (Fe, Mn, Zn and Pb were determined in each fraction. The obtained results show that the average amounts of heavy metals in different fractions are related to the particle size of the soil especially the fine fraction. Heavy metals content was always in the surface layers higher than sub-surface. All metals were highest in clay fraction followed by silt and sand fractions respectively. This investigation discussed the importance of the fine fractions in the accumulation of heavy metals by coordination number in the lattice structure.
Chemical fractionation of heavy metals in a soil amended with repeated sewage sludge application
International Nuclear Information System (INIS)
Walter, I.; Cuevas, G.
1999-01-01
A sequential extraction method (KNO 3 , NaOH, Na 2 -EDTA, HNO 3 ) was used to determine the soil fraction of Zn, Cd, Cu, Ni, Pb, and Cr in different plots treated with sewage sludges. The sludges were applied to cropland from 1983 to 1991. Soil samples were collected after the 1st and 5th-year of the last sludge application. Sludge applications increased the INOR-fraction for Zn, Cd, and Cu. Cu was the only element found in the EXCH-fraction. Pb and Cr were found mainly in the RES-fraction. Ni was found in the INOR and OM-fractions. All the metals increased in the more resistant fractions. Sewage sludge applications changed the metals distribution of the soil and this effect has continued for at least 5 years. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)
Availability and bio-accessibility of metals in the clay fraction of urban soils of Sevilla
International Nuclear Information System (INIS)
Madrid, F.; Diaz-Barrientos, E.; Madrid, L.
2008-01-01
The availability of Cd, Cr, Cu, Ni, Mn, Pb and Zn present in the finest size particles of urban soils is studied by comparing the concentrations in the clay fraction with those extracted from the whole soil by either single-extraction or sequential extraction method. Many metals are preferentially present in the finest particles as compared to coarser fractions. This is true for most metals studied, except Mn and, perhaps, Cd. Those metals present in the clay fraction are often in easily bio-accessible forms, especially Cu, Pb and Zn. The results suggest that bio-accessible forms of these three metals are distributed among the three sequential fractions, and even the fraction considered as 'residual' is also bio-accessible to a significant extent. The statistical analysis shows some distinctions among metals that are compared to the 'urban', 'natural', or intermediate behaviour of the various metals as proposed earlier in the literature. - The recreational use of most urban soils causes that the availability of metals in the finest soil particles must be studied and eventually controlled
Improved Fractional Order VSS Inc-Cond MPPT Algorithm for Photovoltaic Scheme
Directory of Open Access Journals (Sweden)
R. Arulmurugan
2014-01-01
Full Text Available Nowadays a hot topic among the research community is the harnessing energy from the free sunlight which is abundant and pollution-free. The availability of cheap solar photovoltaic (PV modules has to harvest solar energy with better efficiency. The nature of solar modules is nonlinear and therefore the proper impedance matching is essential. The proper impedance matching ensures the extraction of the maximum power from solar PV module. Maximum power point tracking (MPPT algorithm is acting as a significant part in solar power generating system because it varies in the output power from a PV generating set for various climatic conditions. This paper suggested a new improved work for MPPT of PV energy system by using the optimized novel improved fractional order variable step size (FOVSS incremental conductance (Inc-Cond algorithm. The new proposed controller combines the merits of both improved fractional order (FO and variable step size (VSS Inc-Cond which is well suitable for design control and execution. The suggested controller results in attaining the desired transient reaction under changing operating points. MATLAB simulation effort shows MPPT controller and a DC to DC Luo converter feeding a battery load is achieved. The laboratory experimental results demonstrate that the new proposed MPPT controller in the photovoltaic generating system is valid.
Cai, Jiannan; Cao, Yingzi; Tan, Haijian; Wang, Yanman; Luo, Jiaqi
2011-09-01
Surface sediments collected from nine urban rivers located in Zhongshan City, Pearl River Delta, were analyzed for total concentration of metals with digestion and chemical fractionation adopting the modified European Community Bureau of Reference (BCR) sequential extraction procedure. The results showed that concentration and fractionation of metals varied significantly among the rivers. The total concentration of eight metals in most rivers did not exceed the China Environmental Quality Standard for Soil, Grade III. The potential ecological risk of metals to rivers were related to the land use patterns, in the order of manufacturing areas > residential areas > agriculture areas. The concentration of Pb in the reducible fraction was relatively high (60.0-84.3%). The dominant proportions of Cd, Zn and Cu were primary in the non-residual fraction (67.0%, 71.8% and 81.4% on average respectively), while the percentages of the residual fractions of Cr and Ni varied over a wide range (43-85% and 24-71% respectively). The approaches of the Håkanson ecological risk index and Secondary Phase Enrichment Factor were applied for ecological risk assessment and metal enrichment calculation. The results indicated Hg and Cd had posed high potential ecological risk to urban rivers in this region. Meanwhile, there was widespread pollution and high enrichment of Cu in river sediments in this region. Multiple regression analysis showed that five water quality parameters (pH, DO, COD(Mn), NH(4)(+)-N, TP) had little influence on the distribution of metal fractionation. This result revealed that the ecological risk of metals was not eliminated along with the improvement in water quality. Correlation studies showed that among the metals, Group A (Cd, As, Pb, Zn Hg, r = 0.730-0.924) and Group B (Cr, Cu, Ni, r = 0.815-0.948) were obtained, and the metal contaminations were from industrial activities rather than residential.
Siderophile element fractionation in meteor crater impact glasses and metallic spherules
Mittlefehldt, David W.; See, T. H.; Scott, E. R. D.
1993-01-01
Meteor Crater, Arizona provides an opportunity to study, in detail, elemental fractionation processes occurring during impacts through the study of target rocks, meteorite projectile and several types of impact products. We have performed EMPA and INAA on target rocks, two types of impact glass and metallic spherules from Meteor Crater. Using literature data for the well studied Canyon Diablo iron we can show that different siderophite element fractionations affected the impact glasses than affected the metallic spherules. The impact glasses primarily lost Au, while the metallic spherules lost Fe relative to other siderophile elements.
Wang, Zheng; Hall, Philip; Miles, Nicholas J; Wu, Tao; Lambert, Peter; Gu, Fu
2015-09-01
Waste electrical and electronic equipment (WEEE) is one of the fastest growing waste streams worldwide with volumes increasing by 40% each year. WEEE has attracted increasing concern worldwide due to its high metal content and the potential environmental threat which results from uncontrolled recycling practices. Innovative physical separation techniques for WEEE recycling are preferential compared with chemical methods because of the reduction of energy and chemical consumption as well as potential environmental threats. Pneumatic jigging is a dry separation process capable of achieving good separation of coarse material within a very narrow density range, which makes it suitable as a pretreatment process for WEEE recycling. The work presented in this paper investigates the potential application of pneumatic jigging in metal recovery from WEEE. A pilot scale pneumatic jig has been developed by University of Nottingham Ningbo to separate shredded printed wiring boards into two streams: a light fraction (mainly non-metallic fraction consisting of glass fiber, fluffs, and plastic pieces) and dense fraction (metallic fraction). The novelty of work presented in this paper is the application of a dry separation technique in WEEE recycling for metal recovery. Compared with conventional wet separation processes involved in WEEE recycling industry, dry separation has the advantage of zero secondary pollution. The results of this experimental program show pneumatic jigging to be an effective and environmental friendly technique as a pretreatment process for the recovery of the metallic fraction from shredded WEEE. © The Author(s) 2015.
Nowack, Bernd; Schulin, Rainer; Luster, Jörg
2010-10-01
In a lysimeter experiment, topsoils were polluted with filter dust from a non-ferrous metal smelter and then planted with trees. Sequential extractions were used to follow the changes in metal fractionation of Cu, Zn, Cd, and Pb over 42 months. Plant-free and uncontaminated soils served as reference. In the contaminated and planted soils, the largest changes in speciation occurred within the first 6 months. The relative amounts of certain metal fractions were linearly related to each other, indicating systematic redistribution between fractions. The results indicate that under natural conditions with high heterogeneity in total metal contents spatial differences are more important than temporal variations in determining the fractionation and solubility of metals in contaminated soils. In the absence of plants soils exhibited a completely different fractionation 30 months after pollution, with much higher proportions in the more refractory phases. This suggests that plant activity kept the metals in a more soluble form. Copyright (c) 2010 Elsevier Ltd. All rights reserved.
Scheme for the fabrication of ultrashort channel metal-oxide-semiconductor field-effect transistors
International Nuclear Information System (INIS)
Appenzeller, J.; Martel, R.; Solomon, P.; Chan, K.; Avouris, Ph.; Knoch, J.; Benedict, J.; Tanner, M.; Thomas, S.; Wang, K. L.
2000-01-01
We present a scheme for the fabrication of ultrashort channel length metal-oxide-semiconductor field-effect transistors (MOSFETs) involving nanolithography and molecular-beam epitaxy. The active channel is undoped and is defined by a combination of nanometer-scale patterning and anisotropic etching of an n ++ layer grown on a silicon on insulator wafer. The method is self-limiting and can produce MOSFET devices with channel lengths of less than 10 nm. Measurements on the first batch of n-MOSFET devices fabricated with this approach show very good output characteristics and good control of short-channel effects. (c) 2000 American Institute of Physics
DEFF Research Database (Denmark)
Hansen, Elo Harald
Determination of low or trace-level amounts of metals by electrothermal atomic absorption spectrometry (ETAAS) often requires the use of suitable preconcentration and/or separation procedures in order to attain the necessary sensitivity and selectivity. Such schemes are advantageously executed...... by superior performance and versatility. In fact, two approaches are conceivable: The analyte-loaded ion-exchange beads might either be transported directly into the graphite tube where they are pyrolized and the measurand is atomized and quantified; or the loaded beads can be eluted and the eluate forwarded...
Heavy-metal contamination and solid-phase fractionation in street dust.
Merrikhpour, Hajar; Mahdavi, Shahriar
2017-09-03
Fourteen street-dust samples were collected from Hamedan, western Iran. Street-dust samples received different amounts of heavy-metal pollution. The samples were analyzed for total cadmium (Cd), copper (Cu), lead (Pb), nickel (Ni), and zinc (Zn), and binding forms of heavy metal were determined in five fractions. The results showed Cd was the only metal present appreciably, 25.21% and 25.92%, in the exchangeable and carbonates fractions, respectively, and Cu was the only metal predominantly associated, 31.77%, with organic fraction. Zn, 45.84%, was present mainly in the Fe-Mn oxide fraction, and the residual fraction was the most dominant solid phase pool of Ni and Pb, respectively, with 42.56% and 41.31%. The order of apparent mobility and potential metal bioavailability for these contaminated street-dust samples is Cd > Zn > Cu > Pb > Ni. The risk-assessment code results showed very high risk for Cd; medium risk for Cu, Pb, and Zn; and low risk for Ni.
International Nuclear Information System (INIS)
Manning, Matthew A.; Arthur, Douglas W.; Schmidt-Ullrich, Rupert K.; Arnfield, Mark R.; Amir, Cyrus; Zwicker, Robert D.
2000-01-01
brachytherapy provides a convenient outpatient method for boosting the lumpectomy cavity following conventional whole breast irradiation without overdosing normal tissues. The fractionation scheme of 15 Gy in 6 fractions over 3 days is well tolerated. The volume of tissue removed from the breast at lumpectomy appears to dominate cosmetic outcome in this group of patients.
The impact of sewage sludge treatment on the content of selected heavy metals and their fractions.
Ignatowicz, Katarzyna
2017-07-01
The aim of the study was to assess the physicochemical properties of compost made of municipal sewage sludge from selected Municipal Sewage Treatment Plant. Content of basic macroelements and heavy metals (Zn, Cu, Cr, Cd, Ni, Pb, Hg, Mg, Ca, N, P, K, Na) and their fractions was determined by means of BCR method. Based on the analyzes, it was found that the content of heavy metals in compost did not exceed the limits set by natural land management of sewage sludge; the compost is very abundant in biogenic elements - nitrogen and phosphorus - and it can be also considered a significant source of calcium and magnesium. The analysis of results obtained from the three-stage chemical extraction revealed that deposits subjected to aerobic stabilization and composting accumulate metals (in descending sequence) in fractions III and II, i.e. fractions virtually inaccessible to the ecosystem in optimal conditions of use. Copyright © 2017 Elsevier Inc. All rights reserved.
Chemical fractionation and health risk assessment of particulate matter-bound metals in Pune, India.
Jan, Rohi; Roy, Ritwika; Yadav, Suman; Satsangi, P Gursumeeran
2018-02-01
The present study deals with the assessment of sequential extraction of particulate matter (PM)-bound metals and the potential health risks associated with them in a growing metropolitan city (Pune) of India. The average mass concentration of both PM 2.5-10 and PM 2.5 exceeded the National Ambient Air Quality Standards. Significant seasonal variation in mass concentration was found for both size fractions of PM with higher values in winter season and lower in monsoon. Chemical species of the studied trace metals in PM exhibited significant differences, due to difference in sources of pollution. Metals such as Cd, Pb, and Cr in both size fractions and Zn and Co in fine fraction were more efficiently extracted in mobile fractions showing their mobile nature while Ni and Fe showed reduced mobility. Fe showed the highest concentrations among all the analyzed elements in both coarse (PM 2.5-10 ) and fine (PM 2.5 ) PM, while Cd showed least concentration in both size fractions. PCA identified industrial emissions, vehicular activity, coal combustion, diesel exhaust, waste incineration, electronic waste processing, constructional activities, soil, and road dust as probable contributors responsible for the metallic fraction of PM. All the metals showed varying contamination in PM samples. The contamination was higher for fine particles than coarse ones. The average global contamination factor was found to be 27.0-34.3 in coarse and fine PM, respectively. The hazard quotient (HQ) estimated for Cd, Co, and Ni (both total and easily accessible concentrations) exceeded the safe level (HQ = 1), indicating that these metals would result in non-carcinogenic health effects to the exposed population. The HQ ranged from 9.1 × 10 -5 for Cu (coarse) to 8.3 for Ni (fine) PM. The cancer risk for Cd, Ni, and Cr in both sized PM were much higher than the acceptable limits of USEPA.
Heavy Metal and PAH Concentrations in Highway Runoff Deposits Fractionated on Settling Velocities
DEFF Research Database (Denmark)
Bentzen, Thomas Ruby; Larsen, Torben
2009-01-01
the relationship between the settling velocity of the runoff particles and the corresponding metal and polyaromatic hydrocarbon (PAH) concentration directly instead of dealing with two unknowns-the density and the shape of a single particle fraction in a settling velocity calculations. The measurements show...... and copper and there is no significant correlation between PAH concentration and settling velocity. The largest mass of metals and PAH within each pond can be found on the particle fraction with a settling velocity of 5.5-2.5 mm/s....
Dynamics of a Rydberg hydrogen atom near a metal surface in the electron-extraction scheme
Energy Technology Data Exchange (ETDEWEB)
Iñarrea, Manuel [Área de Física Aplicada, Universidad de La Rioja, Logroño (Spain); Lanchares, Víctor [Departamento de Matemáticas y Computación, Universidad de La Rioja, Logroño, La Rioja (Spain); Palacián, Jesús [Departamento de Ingeniería Matemática e Informática, Universidad Pública de Navarra, Pamplona (Spain); Pascual, Ana I. [Departamento de Matemáticas y Computación, Universidad de La Rioja, Logroño, La Rioja (Spain); Salas, J. Pablo, E-mail: josepablo.salas@unirioja.es [Área de Física Aplicada, Universidad de La Rioja, Logroño (Spain); Yanguas, Patricia [Departamento de Ingeniería Matemática e Informática, Universidad Pública de Navarra, Pamplona (Spain)
2015-01-23
We study the classical dynamics of a Rydberg hydrogen atom near a metal surface in the presence of a constant electric field in the electron-extraction situation [1], e.g., when the field attracts the electron to the vacuum. From a dynamical point of view, this field configuration provides a dynamics richer than in the usual ion-extraction scheme, because, depending on the values of field and the atom–surface distance, the atom can be ionized only towards the metal surface, only to the vacuum or to the both sides. The evolution of the phase space structure as a function of the atom–surface distance is explored in the bound regime of the atom. In the high energy regime, the ionization mechanism is also investigated. We find that the classical results of this work are in good agreement with the results obtained in the wave-packet propagation study carried out by So et al. [1]. - Highlights: • We study a classical hydrogen atom near a metal surface plus a electric field. • We explore the phase space structure as a function of the field strength. • We find most of the electronic orbits are oriented along the field direction. • We study the ionization of the atom for several atom–surface distances. • This classical study is in good agreement with the quantum results.
International Nuclear Information System (INIS)
Sugano, Yasutaka; Mizuta, Masahiro; Takao, Seishin; Shirato, Hiroki; Sutherland, Kenneth L.; Date, Hiroyuki
2015-01-01
Purpose: Radiotherapy of solid tumors has been performed with various fractionation regimens such as multi- and hypofractionations. However, the ability to optimize the fractionation regimen considering the physical dose distribution remains insufficient. This study aims to optimize the fractionation regimen, in which the authors propose a graphical method for selecting the optimal number of fractions (n) and dose per fraction (d) based on dose–volume histograms for tumor and normal tissues of organs around the tumor. Methods: Modified linear-quadratic models were employed to estimate the radiation effects on the tumor and an organ at risk (OAR), where the repopulation of the tumor cells and the linearity of the dose-response curve in the high dose range of the surviving fraction were considered. The minimization problem for the damage effect on the OAR was solved under the constraint that the radiation effect on the tumor is fixed by a graphical method. Here, the damage effect on the OAR was estimated based on the dose–volume histogram. Results: It was found that the optimization of fractionation scheme incorporating the dose–volume histogram is possible by employing appropriate cell surviving models. The graphical method considering the repopulation of tumor cells and a rectilinear response in the high dose range enables them to derive the optimal number of fractions and dose per fraction. For example, in the treatment of prostate cancer, the optimal fractionation was suggested to lie in the range of 8–32 fractions with a daily dose of 2.2–6.3 Gy. Conclusions: It is possible to optimize the number of fractions and dose per fraction based on the physical dose distribution (i.e., dose–volume histogram) by the graphical method considering the effects on tumor and OARs around the tumor. This method may stipulate a new guideline to optimize the fractionation regimen for physics-guided fractionation
Stacey, Peter R
2006-06-01
This paper discusses the proficiency of laboratories analysing identical test samples representative of metals in air in the Workplace Analysis Scheme for Proficiency (WASP) and the variability of results from laboratories used to assess personal exposure in the workplace. Over 11 years, the performance of laboratories has significantly improved for lead, cadmium and chromium. Laboratories show better agreement when using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) than flame atomic absorption spectroscopy (FAAS) when analysing chromium, but not when analysing lead and cadmium. Data from the proficiency testing scheme show that for a customer to have confidence that a measurement value does not exceed the workplace exposure limit the analytical result would have to be performance criterion for satisfactory performance (+/-8.3%) was found to be appropriate as long as laboratories participated consecutively in all rounds. Estimates of the overall uncertainty of results from ICP-AES and FAAS analysis were shown to meet the criteria in EN482. Samples from some types of workplace environments are more difficult than the WASP test material to dissolve into solution, so it is expected that estimates of uncertainty are larger for less soluble analytes and matrices. WASP has now initiated a programme to help laboratories assess their performance with more complex matrices.
Nasr, Samir M; Okbah, Mohamed A; El Haddad, Huda S; Soliman, Naglaa F
2015-07-01
A five-step sequential extraction technique, following Tessier's protocol, has been applied to determine the chemical association of Cd, Cu, Fe, Pb, and Zn with major sedimentary phases (exchangeable, carbonate, manganese and iron oxides, organic and residual fraction) in surface sediments from 14 stations off the Libyan Mediterranean coast. This study is a first approach of chemical fractionation of these metals in one of the most economically important area of the Libyan coastline in Mediterranean Sea. The total metal content was also determined. The total concentration of metals ranged from 5-10.5 mg/kg for Cd, 9.1-22.7 mg/kg for Cu, 141.8-1056.8 mg/kg for Fe, 18.9-56.9 mg/kg for Pb, and 11.6-30.5 mg/kg for Zn. The results of the partitioning study showed that the residual form was the dominant fraction of the selected metals among most of the studied locations. The degree of surface sediment contamination was computed for risk assessment code (RAC), individual contamination factor (ICF), and Global contamination factor (GCF). Risk assessment code classification showed that the relative amounts of easily dissolved phase of trace metals in the sediments are in the order of Pb>Zn>Cd>Cu>Fe. The results of ICF and GCF showed that Sirt and Abu Kammashand had higher GCF than other sites indicating higher environmental risk. In terms of ICF value, a decrease order in environmental risk by trace metals was Pb>Zn>Cu>Cd>Fe. Therefore, Pb had highest risk to water body.
Release to the gas phase of metals, S and Cl during combustion of dedicated waste fractions
DEFF Research Database (Denmark)
Pedersen, Anne Juul; van Lith, Simone Cornelia; Frandsen, Flemming
2010-01-01
The release to the gas phase of inorganic elements such as alkali metals. Cl, S, and heavy metals in Waste-to-Energy (WtE) boilers is a challenge. Besides the risk of harmful emissions to the environment, inorganic elements released from the grate may cause severe ash deposition and corrosion...... wood, shoes, automotive shredder waste and PVC (poly-vinyl-chloride). The waste fractions were characterized by use of wet chemical analysis, and, based on the chemical composition of the initial fuel sample and the ash residue after the experiments; the release of inorganic elements was quantified....... The lab-scale release results were then compared with results from a related, full-scale partitioning study, in which test runs with the addition of similar, dedicated waste fractions to a base-load waste had been performed in a grate-fired WtE boiler. In general, the elements Al, Ca, Cr, Cu, Fe, Mg, Si...
Distribution and fractionation of heavy metals in the Tisa (Tisza) river sediments.
Sakan, Sanja; Grzetić, Ivan; Dordević, Dragana
2007-06-01
In this work, sediments of the River Tisa (Tisza) are studied to assess their environmental pollution levels for some major heavy metals, as well as to predict the investigated elements' mobility on the basis of their association type with the substrate. The Tisa River catchments area is a subbasin of the River Danube. Part of this river, 166 km long, belongs to the Serbian province of Vojvodina, before it flows into the Danube. It has been chosen for our investigation, because it has been exposed to intense pollution in the last decades. The river sediment samples were collected at 32 locations. The proportions of sand, silt and clay fractions were determined. The sequential extraction procedure following a modified Tessier method was applied for speciation of the metal forms in the collected samples. The metal concentrations of Zn, Cd, Pb, Ni, Cu, Cr, Fe and Mn in extracts were determined by atomic absorption spectroscopy. Granulometric analysis showed that some 50% of the Tisa River sediments were silt and clay, while the rest was sand with quartz, as the main constituent. The average metal content of the surface river sediment samples for every fraction of sequential extraction was presented and discussed in relation to pH, Eh and metal fractionation. The average metal content from the Tisa River sediments, obtained as an average of the metal's concentration released in all five sequential extraction fractions was compared with: average metal contents of the Tisa River sediments in Hungary, metal content in soils formed on the Tisa River alluvium of Vojvodina, average metal content in soils of Vojvodina, and average metal content in soils of Hungary. An assessment of metal pollution levels in Tisa River sediments was made by comparing mean values for obtained results for the Tisa River sediments with the freshwater sediment's Quality Guidelines as published by US EPA, Environment Canada and soil standards for Serbia. According to US EPA and Canadian Quality
Fracture and toughening of high volume fraction ceramic particle reinforced metals
Miserez, Ali Gilles Tchenguise
2003-01-01
This work contributes to the fundamental understanding of fracture properties of Particle Reinforced Metal Matrix Composites (PRMMCs), by identifying the key microstructural parameters that control fracture. To this end, PRMMCs with a high volume fraction of ceramic reinforcement (40-60 vol.%) are produced by gas-pressure infiltration. These composites are considered as model ductile/brittle twophase materials in that (i): the particles are homogeneously distributed in the matrix, (ii): the m...
Fracture and toughening of high volume fraction ceramic particle reinforced metals
Miserez, Ali Gilles Tchenguise; Mortensen, Andreas
2005-01-01
This work contributes to the fundamental understanding of fracture properties of Particle Reinforced Metal Matrix Composites (PRMMCs), by identifying the key microstructural parameters that control fracture. To this end, PRMMCs with a high volume fraction of ceramic reinforcement (40-60 vol.%) are produced by gas-pressure infiltration. These composites are considered as model ductile/brittle twophase materials in that (i): the particles are homogeneously distributed in the matrix, (ii): the m...
Influences of nanotwin volume fraction on the ballistic performance of coarse-grained metals
Directory of Open Access Journals (Sweden)
Q.D. Ouyang
2017-09-01
Full Text Available Coarse-grained (CG metals strengthened by nanotwinned (NT regions possess high strength and good ductility. As such, they are very suitable for applications in bullet-proof targets. Here, a numerical model based on the conventional theory of strain gradient plasticity and the Johnson–Cook failure criterion is employed to study the influences of volume fraction of NT regions on their ballistic performance. The results show that in general a relatively small twin spacing (4–10 nm and a moderate volume fraction (7%–20% will lead to excellent limit velocity and that the influences of volume fraction on limit displacement change with the category of impact processes.
International Nuclear Information System (INIS)
Li, Yuanhui; Xie, Quan; Wang, Wei; Zhang, Hao; Lei, Yinhua; Zhang, Haixia Alice; Wu, Wengang; Li, Zhihong; Zheng, Mingxin
2011-01-01
This work introduced a novel spacer scheme for polymer/metal nanowire preparation by combining Parylene C and photoresist (Parylene C on photoresist, POP, process), both of which possess a low temperature fabrication essence. Adhesion between the Parylene C and the substrate with photoresist onside was improved by introducing a modified silanization pretreatment. Parylene C filled in an undercut generated by regular lithography on a dual-layered photoresist was left as nanometer-sized residues after an isotropic oxygen plasma etching. Parylene C nanowires with the minimal width down to 200 nm were successfully obtained by this POP-based spacer technique, and were then utilized as the etching mask for ion milling of the metal films beneath to realize corresponding chromium/gold nanowires. The present POP scheme will expand the application of the spacer technique in polymer/metal nanowire fabrication for integrated micro/nanoelectromechanical systems. (technical note)
Predicting trace metal solubility and fractionation in Urban soils from isotopic exchangeability.
Mao, L C; Young, S D; Tye, A M; Bailey, E H
2017-12-01
Metal-salt amended soils (MA, n = 23), and historically-contaminated urban soils from two English cities (Urban, n = 50), were investigated to assess the effects of soil properties and contaminant source on metal lability and solubility. A stable isotope dilution method, with and without a resin purification step, was used to measure the lability of Cd, Cu, Ni, Pb and Zn. For all five metals in MA soils, lability (%E-values) could be reasonably well predicted from soil pH value with a simple logistic equation. However, there was evidence of continuing time-dependent fixation of Cd and Zn in the MA soils, following more than a decade of storage under air-dried conditions, mainly in high pH soils. All five metals in MA soils remained much more labile than in Urban soils, strongly indicating an effect of contaminant source on metal lability in the latter. Metal solubility was predicted for both sets of soil by the geochemical speciation model WHAM-VII, using E-value as an input variable. For soils with low metal solution concentrations, over-estimation of Cd, Ni and Zn solubility was associated with binding to the Fe oxide fraction while accurate prediction of Cu solubility was dependent on humic acid content. Lead solubility was most poorly described, especially in the Urban soils. Generally, slightly poorer estimation of metal solubility was observed in Urban soils, possibly due to a greater incidence of high pH values. The use of isotopically exchangeable metal to predict solubility is appropriate both for historically contaminated soils and where amendment with soluble forms of metal is used, as in toxicological trials. However, the major limitation to predicting solubility may lie with the accuracy of model input variables such as humic acid and Fe oxide contents where there is often a reliance on relatively crude analytical estimations of these variables. Trace metal reactivity in urban soils depends on both soil properties and the original source material
Adsorption of Different Fractions of Organic Matter on the Surface of Metal Oxide
Zaouri, Noor A
2013-05-18
The adsorption of different fractions of organic matter on the surface of Al2O3 and ZrO2 were investigated. The aim was to study the affinity of these fractions on the surface of metal oxide and the effect of several factors. Batch adsorption experiments were conducted with Low molecular weight oxygenated compounds. These chemical compound have been chosen to investigate:1) the aliphatic and aromatic structurer;2)contribution of hydroxyl group and; 3) the number of carboxyl group. HPLC and IC analysis used for determent the concentration of these chemical in the working solution. ATR-FTIR used to distinguish the type of coordination structure with the surface of metal oxide. The results fitted with Langmuir equation. The results showed that the chemical structure and the type and number of attached functional have an impact on the adsorption. Which it was proved via ATR-FTIR where the result showed that each chemical have different coordination structure on the surface of ZrO2 and Al2O3. Different fractions and sources of NOM were used (hydrophobic fraction of Suwannee and Colorado River, biopolymers extracted for the exuded of 2 species of algae, and low molecular acids that do not adsorb in XAD-8 resin). Results showed that these different fractions have different affinity with the surface of Al2O3 and ZrO2. These adsorption behaviors were varying according to the difference in the component of each NOM. Biopolymers showed significant adsorption at acidic pH. These biopolymers are mainly comprised of polysaccharides and this result proved that polysaccharide adsorb on the surface of ZrO2 more than Al2O3.
Experimental Characterization of Ionic Polymer Metal Composite as a Novel Fractional Order Element
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Riccardo Caponetto
2013-01-01
Full Text Available Ionic polymer metal composites (IPMCs are electroactive materials made of ionic polymer thin membranes with platinum metallization on their surfaces. They are interesting materials due to not only their electromechanical applications as transducers but also to their electrochemical features and the relationship between the ionic/solvent current and the potential field. Their electrochemical properties thus suggest the possibility for exploiting them as compact fractional-order elements (FOEs with a view of defining fabrication processes and production strategies that assure the desired performances. In this paper, the experimental electrical characterization of a brand new IPMC setup in a fixed sandwich configuration is proposed. Two IPMC devices with different platinum absorption times (5 h and 20 h are characterized through experimental data: first, a preliminary linearity study is performed for a fixed input voltage amplitude in order to determine the frequency region where IPMC can be approximated as linear; then, a frequency analysis is carried out in order to identify a coherent fractional-order dynamics in the bode diagrams. Such analyses take the first steps towards a simplified model of IPMC as a compact electronic FOE for which the fractional exponent value depends on fabrication parameters as the absorption time.
Ghous, Tahseen; Aziz, Nouman; Mehmood, Zahid; Andleeb, Saiqa
2015-07-01
Momordica charantia is commonly used as a vegetable and folk medicine in most parts of South Asia. This study aims to determine and compare the antioxidant, metal chelating and antiglycation activities of aqueous extracts of M. charantia fruit flesh (MCF) and fruit pulp (MCP) fractions. Our results show that MCP has pronounced DPPH and ABTS radical scavenging potential compared to MCF. In the antiglycation assay both fractions illustrated considerable inhibitory activities against the formation of AGEs induced by glucose with an efficacy of 75 and 67% with 150 μl of MCP and MCF extracts respectively, almost equal to 0.3mM amino guanidine. Results for metal catalysed protein fragmentation and autoxidative and glycoxidation assays demonstrate that MCF and MCP inhibited metal catalysed protein fragmentation. The percentage of relative standard deviation for three replicate measurements of 150 μl of MCF and MCP was < 3.0% for antiglycation. The antioxidant assays with regression values of MCP (0.981 and 0.991) and MCF (0.967 and 0.999) were also recorded. We conclude that both extracts possess high antioxidant and antiglycation activities and are equally good sources of antioxidant and antiglycating agents.
Comparison of sample preparation procedures on metal(loid) fractionation patterns in lichens.
Kroukamp, E M; Godeto, T W; Forbes, P B C
2017-08-13
The effects of different sample preparation strategies and storage on metal(loid) fractionation trends in plant material is largely underresearched. In this study, a bulk sample of lichen Parmotrema austrosinense (Zahlbr.) Hale was analysed for its total extractable metal(loid) content by ICP-MS, and was determined to be adequately homogenous (sample were prepared utilising a range of sample preservation techniques and subjected to a modified sequential extraction procedure or to total metal extraction. Both experiments were repeated after 1-month storage at 4 °C. Cryogenic freezing gave the best reproducibility for total extractable elemental concentrations between months, indicating this to be the most suitable method of sample preparation in such studies. The combined extraction efficiencies were >82% for As, Cu, Mn, Pb, Sr and Zn but poor for other elements, where sample preparation strategies 'no sample preparation' and 'dried in a desiccator' had the best extraction recoveries. Cryogenic freezing procedures had a significantly (p sample cleaning and preservation when species fractionation patterns are of interest. This study also shows that the assumption that species stability can be ensured through cryopreservation and freeze drying techniques needs to be revisited.
Iron isotopic fractionation between silicate mantle and metallic core at high pressure
Liu, Jin; Dauphas, Nicolas; Roskosz, Mathieu; Hu, Michael Y.; Yang, Hong; Bi, Wenli; Zhao, Jiyong; Alp, Esen E.; Hu, Justin Y.; Lin, Jung-Fu
2017-02-01
The +0.1‰ elevated 56Fe/54Fe ratio of terrestrial basalts relative to chondrites was proposed to be a fingerprint of core-mantle segregation. However, the extent of iron isotopic fractionation between molten metal and silicate under high pressure-temperature conditions is poorly known. Here we show that iron forms chemical bonds of similar strengths in basaltic glasses and iron-rich alloys, even at high pressure. From the measured mean force constants of iron bonds, we calculate an equilibrium iron isotope fractionation between silicate and iron under core formation conditions in Earth of ~0-0.02‰, which is small relative to the +0.1‰ shift of terrestrial basalts. This result is unaffected by small amounts of nickel and candidate core-forming light elements, as the isotopic shifts associated with such alloying are small. This study suggests that the variability in iron isotopic composition in planetary objects cannot be due to core formation.
Aydin, K.; Shinde, S.; Suhail, M.; Vyas, A.; Zieher, K. W.
2002-05-01
An acoustic pulse echo scheme for non-intrusive detection of flaws in metal pipelines has been investigated in the laboratory. The primary pulse is generated by a pulsed magnetic field enclosing a short section of a free pipe. The detection is by an electrostatic detector surrounding a short section of the pipe. Reflected pulses from thin areas, with a longitudinal extension of about one pipe radius and a reduction of the wall thickness of 40%, can be detected clearly.
Digital Repository Service at National Institute of Oceanography (India)
Fernandes, L.L.; Nayak, G.N.
) developed for aquatic ecosystems (MacDonald et al. 1996; Long et al. 1998) are considered in this study. These sets are defined as: i) the Threshold Effect level (TEL) and the Probable Effect Level (PEL); and ii) Effect Range Low (ERL) and Effect Range... values along with higher labile fractions of trace metals can be potential sources for their mobility and bioavailability in the aquatic ecosystems (Harikumar and Jisha 2010). In the creek region, high EF values along with greater percentage of liable...
International Nuclear Information System (INIS)
Goyal, Sharad; Daroui, Parima; Khan, Atif J; Kearney, Thomas; Kirstein, Laurie; Haffty, Bruce G
2013-01-01
The aim of this study was to report 3-year outcomes of toxicity, cosmesis, and local control using a once daily fractionation scheme (49.95 Gy in 3.33 Gy once daily fractions) for accelerated partial breast irradiation (APBI) using three-dimensional conformal radiotherapy (3D-CRT). Between July 2008 and August 2010, women aged ≥40 years with ductal carcinoma in situ or node-negative invasive breast cancer ≤3 cm in diameter, treated with breast-conserving surgery achieving negative margins, were accrued to a prospective study. Women were treated with APBI using 3–5 photon beams, delivering 49.95 Gy over 15 once daily fractions over 3 weeks. Patients were assessed for toxicities, cosmesis, and local control rates before APBI and at specified time points. Thirty-four patients (mean age 60 years) with Tis 0 (n = 9) and T1N0 (n = 25) breast cancer were treated and followed up for an average of 39 months. Only 3% (1/34) patients experienced a grade 3 subcutaneous fibrosis and breast edema and 97% of the patients had good/excellent cosmetic outcome at 3 years. The 3-year rate of ipsilateral breast tumor recurrence (IBTR) was 0% while the rate of contralateral breast events was 6%. The 3-year disease-free survival (DFS), overall survival (OS), and breast cancer-specific survival (BCSS) was 94%, 100%, and 100%, respectively. Our novel accelerated partial breast fractionation scheme of 15 once daily fractions of 3.33 Gy (49.95 Gy total) is a remarkably well-tolerated regimen of 3D-CRT-based APBI. A larger cohort of patients is needed to further ascertain the toxicity of this accelerated partial breast regimen
Recycling of non-metallic fractions from waste electrical and electronic equipment (WEEE): a review.
Wang, Ruixue; Xu, Zhenming
2014-08-01
The world's waste electrical and electronic equipment (WEEE) consumption has increased incredibly in recent decades, which have drawn much attention from the public. However, the major economic driving force for recycling of WEEE is the value of the metallic fractions (MFs). The non-metallic fractions (NMFs), which take up a large proportion of E-wastes, were treated by incineration or landfill in the past. NMFs from WEEE contain heavy metals, brominated flame retardant (BFRs) and other toxic and hazardous substances. Combustion as well as landfill may cause serious environmental problems. Therefore, research on resource reutilization and safe disposal of the NMFs from WEEE has a great significance from the viewpoint of environmental protection. Among the enormous variety of NMFs from WEEE, some of them are quite easy to recycle while others are difficult, such as plastics, glass and NMFs from waste printed circuit boards (WPCBs). In this paper, we mainly focus on the intractable NMFs from WEEE. Methods and technologies of recycling the two types of NMFs from WEEE, plastics, glass are reviewed in this paper. For WEEE plastics, the pyrolysis technology has the lowest energy consumption and the pyrolysis oil could be obtained, but the containing of BFRs makes the pyrolysis recycling process problematic. Supercritical fluids (SCF) and gasification technology have a potentially smaller environmental impact than pyrolysis process, but the energy consumption is higher. With regard to WEEE glass, lead removing is requisite before the reutilization of the cathode ray tube (CRT) funnel glass, and the recycling of liquid crystal display (LCD) glass is economically viable for the containing of precious metals (indium and tin). However, the environmental assessment of the recycling process is essential and important before the industrialized production stage. For example, noise and dust should be evaluated during the glass cutting process. This study could contribute
Oyeyiola, Aderonke Oluwabukola; Olayinka, Kehinde O; Alo, Babajide I
2011-01-01
In the determination of the best sequential extraction procedures (SEP) for the speciation of metals in sediment samples from the Lagos lagoon system, three sequential extraction procedures were compared for the fractionation of Cd, Cr, Cu, Pb, and Zn. The SEP compared included a modified Tessier's procedure carried out in five steps, while the two other procedures were the three-step original Community Bureau of Reference (BCR) and the modified BCR techniques (four steps). Quantification of the metal concentration was achieved with a flame atomic absorption spectrophotometer. The results obtained by the three methods were compared, and the modified BCR and Tessier SEP were found to extract more Cu, Cr, Pb, and Zn in the reducible phase and therefore a decrease in the oxidizable phase than the original BCR SEP. The most mobile elements were found to be Cd, Pb, and Zn. These are of environmental concern, as these potentially toxic metals could be easily released into the aquatic environment with consequent ingestion by aquatic organisms, thereby entering the food chain. The mass balance (percent recovery) was found to be between 85% and 115% in most cases. Prior to the comparison, the analytical performance of the laboratory was tested using a secondary reference material, GLAURM, using the three-step modified BCR procedure. The results showed high reliability of the analytical performance of the laboratory for all the metals considered.
Directory of Open Access Journals (Sweden)
Hong Wang
Full Text Available In ex-situ washing, HCl, EDTA and H2O2 solutions can effectively extract heavy metals in river sediment. Nevertheless they often target different sediment components, possibly transforming metal species into more bioavailable and hence toxic ones. This study, in batch settings, investigated the influences of different types of washing agents (i.e. HCl, EDTA and H2O2 on metal (i.e. Cu and Zn removal from contaminated river sediment, destroy or dissolution of sediment components, and transformation of metal fractions during chemical washing treatment. Additionally, bioavailability of these metals left in the washed sediment was assessed. Results showed that HCl obtained the highest Cu and Zn removal through destroying the reducible, oxidizable and residual sediment components. Meanwhile, it transformed metal fractions to acid extractable one, resulting in an increase in metal bioavailability. Thus, the feasibility of washing with HCl for sediment remediation shall be reconsidered due to the caused high metal bioavailability. EDTA was capable of removing metals via direct complexation of labile metal species and indirect dissolution of reducible and oxidizable sediment components, where the transformation of corresponding metal binding fraction may occur. H2O2 obtained the lowest total Cu and Zn removal, but it preferentially removed the oxidizable metal species by oxidizing sulfides in the sediment. The bioavailable levels of Cu and Zn in the sediment washed by EDTA or H2O2 seemed not increase. To maintain a good balance between labile metal species removal and avoiding increase of metal bioavailability, EDTA and H2O2 are promising additives for metal removal by sediment washing.
Orbital-exchange and fractional quantum number excitations in an f-electron metal, Yb2Pt2Pb
Wu, L.S.; Gannon, W.J.; Zaliznyak, I.A.; Tsvelik, A.M.; Brockmann, M.; Caux, J.-S.; Kim, M.S.; Qiu, Y.; Copley, J.R.D.; Ehlers, G.; Podlesnyak, A.; Aronson, M.C.
2016-01-01
Exotic quantum states and fractionalized magnetic excitations, such as spinons in one-dimensional chains, are generally expected to occur in 3d transition metal systems with spin 1/2. Our neutron-scattering experiments on the 4f-electron metal Yb2Pt 2 Pb overturn this conventional wisdom. We observe
Zhang, Lei; Liao, Qianjiahua; Shao, Shiguang; Zhang, Nan; Shen, Qiushi; Liu, Cheng
2015-11-06
Heavy metal (Cr, Ni, Cu, Zn, Cd, and Pb) pollution, fractionation, and ecological risks in the sediments of Lake Chaohu (Eastern China), its eleven inflowing rivers and its only outflowing river were studied. An improved BCR (proposed by the European Community Bureau of Reference) sequential extraction procedure was applied to fractionate heavy metals within sediments, a geoaccumulation index was used to assess the extent of heavy metal pollution, and a risk assessment code was applied to evaluate potential ecological risks. Heavy metals in the Shuangqiao and Nanfei Rivers were generally higher than the other studied sites. Of the three Lake Chaohu sites, the highest concentrations were identified in western Chaohu. Heavy metal pollution and ecological risks in the lake's only outflowing river were similar to those in the eastern region of the lake, to which the river is connected. Heavy metal concentrations occurred in the following order: Cd > Zn > Cu > Pb ≈ Ni ≈ Cr. Cr, Ni, and Cu made up the largest proportion of the residual fraction, while Cd was the most prominent metal in the exchangeable and carbonate-included fraction. Cd posed the greatest potential ecological risk; the heavy metals generally posed risks in the following order: Cd > Zn > Cu > Ni > Pb > Cr.
Acosta, Jose A; Faz, Ángel; Kalbitz, Karsten; Jansen, Boris; Martínez-Martínez, Silvia
2011-11-01
Street dust has been sampled from six different types of land use of the city of Murcia (Spain). The samples were fractionated into eleven particle size fractions (<2, 2-10, 10-20, 20-50, 50-75, 75-106, 106-150, 150-180, 180-425, 425-850 μm and 850-2000 μm) and analyzed for Pb, Cu, Zn and Cd. The concentrations of these four potentially toxic metals were assessed, as well as the effect of particle size on their distribution. A severe enrichment of all metals was observed for all land-uses (industrial, suburban, urban and highways), with the concentration of all metals affected by the type of land-use. Coarse and fine particles in all cases showed concentrations of metals higher than those found in undisturbed areas. However, the results indicated a preferential partitioning of metals in fine particle size fractions in all cases, following a logarithmic distribution. The accumulation in the fine fractions was higher when the metals had an anthropogenic origin. The strong overrepresentation of metals in particles <10 μm indicates that if the finest fractions are removed by a vacuum-assisted dry sweeper or a regenerative-air sweeper the risk of metal dispersion and its consequent risk for humans will be highly reduced. Therefore, we recommend that risk assessment programs include monitoring of metal concentrations in dust where each land-use is separately evaluated. The finest particle fractions should be examined explicitly in order to apply the most efficient measures for reducing the risk of inhalation and ingestion of dust for humans and risk for the environment.
Lang, Jun
2012-01-30
In this paper, we propose a novel secure image sharing scheme based on Shamir's three-pass protocol and the multiple-parameter fractional Fourier transform (MPFRFT), which can safely exchange information with no advance distribution of either secret keys or public keys between users. The image is encrypted directly by the MPFRFT spectrum without the use of phase keys, and information can be shared by transmitting the encrypted image (or message) three times between users. Numerical simulation results are given to verify the performance of the proposed algorithm.
Zou, Bin; Jiang, Xiaolu; Duan, Xiaoli; Zhao, Xiuge; Zhang, Jing; Tang, Jingwen; Sun, Guoqing
2017-03-23
Traditional sampling for soil pollution evaluation is cost intensive and has limited representativeness. Therefore, developing methods that can accurately and rapidly identify at-risk areas and the contributing pollutants is imperative for soil remediation. In this study, we propose an innovative integrated H-G scheme combining human health risk assessment and geographical detector methods that was based on geographical information system technology and validated its feasibility in a renewable resource industrial park in mainland China. With a discrete site investigation of cadmium (Cd), arsenic (As), copper (Cu), mercury (Hg) and zinc (Zn) concentrations, the continuous surfaces of carcinogenic risk and non-carcinogenic risk caused by these heavy metals were estimated and mapped. Source apportionment analysis using geographical detector methods further revealed that these risks were primarily attributed to As, according to the power of the determinant and its associated synergic actions with other heavy metals. Concentrations of critical As and Cd, and the associated exposed CRs are closed to the safe thresholds after remediating the risk areas identified by the integrated H-G scheme. Therefore, the integrated H-G scheme provides an effective approach to support decision-making for regional contaminated soil remediation at fine spatial resolution with limited sampling data over a large geographical extent.
Habib, Muddasar; Miles, Nicholas J; Hall, Philip
2013-03-01
The need to recover and recycle valuable resources from Waste Electrical and Electronic Equipment (WEEE) is of growing importance as increasing amounts are generated due to shorter product life cycles, market expansions, new product developments and, higher consumption and production rates. The European Commission (EC) directive, 2002/96/EC, on WEEE became law in UK in January 2007 setting targets to recover up to 80% of all WEEE generated. Printed Wire Board (PWB) and/or Printed Circuit Board (PCB) is an important component of WEEE with an ever increasing tonnage being generated. However, the lack of an accurate estimate for PCB production, future supply and uncertain demands of its recycled materials in international markets has provided the motivation to explore different approaches to recycle PCBs. The work contained in this paper focuses on a novel, dry separation methodology in which vertical vibration is used to separate the metallic and non-metallic fractions of PCBs. When PCBs were comminuted to less than 1mm in size, metallic grades as high as 95% (measured by heavy liquid analysis) could be achieved in the recovered products. Copyright © 2012 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Shima Rostami
2016-08-01
Full Text Available The main objective of the present study is to evaluate variation, contamination and speciation of heavy metals in bed sediments of the Siahrood River in Mazandaran Province. For this purpose, fifteen sediment samples were collected along the main channel of the river. In addition to total content of heavy metals and selected physiochemical properties of the sediments, geochemical species of heavy metals were determined operationally using the modified BCR method. The obtained results generally showed that there is a wide variation in heavy metal concentrations in the sediments, probably due to anthropogenic inputs into the river and effect of physicochemical properties of the sediments (organic matter and clay content on the heavy metals variability. The calculated Igeo (Geo-accumulation index for each metal also revealed that sediments are moderately or strongly contaminated in terms of Pb and Cd whereas not or slightly contaminated with respect to other heavy metals, suggesting an anthropogenic source for Pb and Cd and a mostly geogenic origin for Ni, Zn, and Cr (Arsenic is probably of a mixed source. The results of BCR method indicated that Pb and Cd are predominately incorporated into the first fraction (F1, acid-soluble fraction while Zn and Ni are mainly associated with residual fraction (F4 confirming the concluded remarks on discrimination of heavy metals origins in the sediments.
Determination of metals in thoracic fraction of ambient air particulate matter
Energy Technology Data Exchange (ETDEWEB)
Bruno, P. [Istituto Inquinamento Atmosferico, Consiglio Nazionale delle Ricerche, Monterotondo, Rome (Italy); Canepari, S.; Cardarelli, E.; Del Cavaliere, C.; Ghighi, S. [Rome Univ. La Sapienza, Rome (Italy). Dept. of Chemistry
2000-12-01
The present work deals with the optimization and validation of a method for the quantitative simultaneous ICP determination of metals in ambient air particulate matter. The attention has been focused on the thoracic fraction (PM10) and twelve different metals were chosen on the basis of their toxicity and of their possible use as chemical tracers. The microwave acidic digestion of the samples has been performed in the presence of different reagents and under different conditions and particular attention has been paid to the optimization of the whole analytical procedure and to the evaluation of accuracy and precision related to the single operative steps. The interferences due to the reagents and to the sampling supports have also been evaluated. In addition, the analytical procedure has been checked by examining the equivalence of results related to parallel sampled filters pairs. [Italian] Il lavoro riguarda l'ottimizzazione e la validazione di una metodica per la determinazione simultanea mediante ICP di metalli nel materiale particellare sopseso. In particolare, l'attenzione e' stata rivolta alla frazione respirabile (PM10) ed ha riguardato dieci differenti metalli, scelti sulla base della tossicita' e di un loro possibile impiego come traccianti chimici. Sono state esaminate differenti metodiche di digestione acida con microonde, impiegando differenti reattivi e differenti condizioni di mineralizzazione. E' stata posta particolare attenzione all'ottimizzazione del procedimento analitico ed alla valutazione della riproducibilita' ed accuratezza associate ai singoli stadi operativi. E' stata inoltre valutata l'entita' delle interferenze causate dall'impiego di reattivi a diverso grado di purezza e dei supporti impiegati per il campionamento. Infine il metodo e' stato validato esaminando l'equivalenza dei dati analitici relativi a coppie di filtri campionati in parallelo.
Li, Ruili; Chai, Minwei; Qiu, Guo Yu
2016-01-01
Overlying water, sediment, rhizosphere sediment and mangrove seedlings in the Futian mangrove forest were analyzed for heavy metals. The results showed that mangrove plant acidified sediment and increased organic matter contents. Except for chromium (Cr), nickel (Ni) and copper (Cu) in Aegiceras corniculatum sediment, heavy metals in all sediments were higher than in overlying water, rhizosphere sediment and mangrove root. Heavy metals in Avicennia marina sediments were higher than other sediments. The lower heavy metal biological concentration factors (BCFs) and translocation factors (TFs) indicated that mangrove plant adopted exclusion strategy. The geo-accumulation index, potential ecological risk index and risk assessment code (RAC) demonstrated that heavy metals have posed a considerable ecological risk, especially for cadmium (Cd). Heavy metals (Cr, Ni, Cu and Cd) mainly existed in the reducible fractions. These findings provide actual heavy metal accumulations in sediment-plant ecosystems in mangrove forest, being important in designing the long-term management and conservation policies for managers of mangrove forest.
Recycling of non-metallic fractions from waste printed circuit boards: A review
International Nuclear Information System (INIS)
Guo Jiuyong; Guo Jie; Xu Zhenming
2009-01-01
The major economic driving force for recycling of waste printed circuit boards (PCBs) is the value of the metallic fractions (MFs) of PCBs. The non-metallic fractions (NMFs), which take up almost 70 wt% of waste PCBs, were treated by combustion or land filling in the past. However, combustion of the NMFs will cause the formation of highly toxic polybrominated dibenzodioxins and dibenzofurans (PBDD/Fs) while land filling of the NMFs will lead to secondary pollution caused by heavy metals and brominated flame retardants (BFRs) leaching to the groundwater. Therefore, recycling of the NMFs from waste PCBs is drawing more and more attention from the public and the governments. Currently, how to recycle the NMFs environmental soundly has become a significant topic in recycling of waste PCBs. In order to fulfill the better resource utilization of the NMFs, the compositions and characteristics of the NMFs, methods and outcomes of recycling the NMFs from waste PCBs and analysis and treatment for the hazardous substances contained in the NMFs were reviewed in this paper. Thermosetting resin matrix composites, thermoplastic matrix composites, concrete and viscoelastic materials are main applications for physical recycling of the NMFs. Chemical recycling methods consisting of pyrolysis, gasification, supercritical fluids depolymerization and hydrogenolytic degradation can be used to convert the NMFs to chemical feedstocks and fuels. The toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) can be used to determine the toxicity characteristic (TC) of the NMFs and to evaluate the environmental safety of products made from the recycled NMFs. It is believed that physical recycling of the NMFs has been a promising recycling method. Much more work should be done to develop comprehensive and industrialized usage of the NMFs recycled by physical methods. Chemical recycling methods have the advantages in eliminating hazardous substances
Hinkley, T.K.; Le Cloarec, M.-F.; Lambert, G.
1994-01-01
Chemical families of metals fractionate systematically as they pass from a silicate melt across the interface with the vapor phase and on into a cooled volcanic plume. We measured three groups of metals in a small suite of samples collected on filters from the plumes of Kilauea (Hawaii, USA), Etna (Sicily), and Merapi (Java) volcanoes. These were the major, minor, and trace metals of the alkali and alkaline earth families (K, Rb, Cs, Ca, Sr, Ba), a group of ordinarily rare metals (Cd, Cu, In, Pb, Tl) that are related by their chalcophile affinities, and the radon daughter nuclides 210Po, 210Bi, and 210Pb. The measurements show the range and some details of systematic melt-vapor fractionation within and between these groups of metals. In the plumes of all three volcanoes, the alkali metals are much more abundant than the alkaline earth metals. In the Kilauea plume, the alkali metals are at least six times more abundant than the alkaline earth metals, relative to abundances in the melt; at Etna, the factor is at least 300. Fractionations within each family are, commonly, also distinctive; in the Kilauea plume, in addition to the whole alkaline earth family being depleted, the heaviest metals of the family (Sr, Ba) are progressively more depleted than the light metal Ca. In plumes of fumaroles at Merapi, K/Cs ratios were approximately three orders of magnitude smaller than found in other earth materials. This may represent the largest observed enrichment of the "light ion lithophile" (LIL) metals. Changes in metal ratios were seen through the time of eruption in the plumes of Kilauea and Etna. This may reflect degree of degassing of volatiles, with which metals complex, from the magma bodies. At Kilauea, the changes in fractionation were seen over about three years; fractionation within the alkaline earth family increased, and that between the two families decreased, over that time. All of the ordinarily rare chalcophile metals measured are extremely abundant in
Xiao, Ling; Guan, Dongsheng; Peart, M R; Chen, Yujuan; Li, Qiqi
2017-01-01
This study was carried out to examine heavy metal accumulation in rice grains and brassicas and to identify the different controls, such as soil properties and soil heavy metal fractions obtained by the Community Bureau of Reference (BCR) sequential extraction, in their accumulation. In Guangdong Province, South China, rice grain and brassica samples, along with their rhizospheric soil, were collected from fields on the basis of distance downstream from electroplating factories, whose wastewater was used for irrigation. The results showed that long-term irrigation using the electroplating effluent has not only enriched the rhizospheric soil with Cd, Cr, Cu, and Zn but has also increased their mobility and bioavailability. The average concentrations of Cd and Cr in rice grains and brassicas from closest to the electroplating factories were significantly higher than those from the control areas. Results from hybrid redundancy analysis (hRDA) and redundancy analysis (RDA) showed that the BCR fractions of soil heavy metals could explain 29.0 and 46.5 % of total eigenvalue for heavy metal concentrations in rice grains and brassicas, respectively, while soil properties could only explain 11.1 and 33.4 %, respectively. This indicated that heavy metal fractions exerted more control upon their concentrations in rice grains and brassicas than soil properties. In terms of metal interaction, an increase of residual Zn in paddy soil or a decrease of acid soluble Cd in the brassica soil could enhance the accumulation of Cd, Cu, Cr, and Pb in both rice grains and brassicas, respectively, while the reducible or oxidizable Cd in soil could enhance the plants' accumulation of Cr and Pb. The RDA showed an inhibition effect of sand content and CFO on the accumulation of heavy metals in rice grains and brassicas. Moreover, multiple stepwise linear regression could offer prediction for Cd, Cu, Cr, and Zn concentrations in the two crops by soil heavy metal fractions and soil properties.
Kalwa, Miguel; Quináia, Sueli Pércio; Pletsch, Adelmo L; Techy, Laura; Felsner, Maria Lurdes
2013-01-01
The objective of this study was to evaluate fractions of metals (labile and pseudo-total) extracted from sediment samples collected in Itaipu Lake (boundary between Brazil and Paraguay) and to assess the dynamics and mobility of these fractions by identifying the same bioavailability and ecological risk to metals in the aquatic environment. The concentrations of metal ions were determined by flame atomic absorption spectrometry. There was a correlation between the metal ions, both in the labile and the pseudo-total, with regard to particle size. To assess metals concentrations in sediment, numerical sediment-quality guidelines were applied. The concentrations of aluminum, cadmium, iron, manganese, lead, and zinc in all sediment samples are lower than the proposed probable effects level (PEL), thus possibly indicating that there are no harmful effects from these metals. In contrast, concentrations of copper, chromium, and nickel exceeded the PEL in some samples, thus indicating that these stations are at potential risk. The level of contamination in sediments of Itaipu Lake for all metals was evaluated using contamination factor, degree of contamination, and sum-of-metals toxic unit.
Yin, Wang; Venderbosch, Hendrikus; Bottari, Giovanni; Krawzcyk, Krzysztof K.; Barta, Katalin; Heeres, Hero Jan
In this work, we report on the catalytic valorization of sugar fractions, obtained by aqueous phase extraction of fast pyrolysis oils, in supercritical methanol (scMeOH) and ethanol (scEtOH) over a copper doped porous metal oxide (Cu-PMO). The product mixtures obtained are, in principle, suitable
Energy Technology Data Exchange (ETDEWEB)
Irvine, Kim N.; Perrelli, Mary F. [State Univ. of New Yrok, Buffalo, NY (United States). Geography and Planning Dept., Buffalo State; Ngoen-klan, Ratchadawan [Chiang Mai Univ. (Thailand). Dept. of Parasitology; Droppo, Ian G. [Water Science and Technology Directorate, Science and Technology Branch, Environment Canada, Burlington, ONT (Canada). Aquatic Ecosystem Management Research Div.
2009-08-15
Background, aim and scope: Street sediment samples were collected at 50 locations in a mixed land use area of Hamilton, Ontario, Canada, and metal levels were analyzed using a sequential extraction procedure for different particle size classes to provide an estimate of potential toxicity as well as the potential for treatment through best management practices (BMPs). Methodology: The street sediment samples were dry sieved into four different particle size categories and a sequential extraction procedure was done on each size category following the methodology proposed by Tessier et al. 1979 using a Hitachi 180-80 Polarized Zeeman Atomic Absorption Spectrophotometer. Results and discussion: Analysis of variance, post hoc least-significant difference tests, and kriging analysis showed that spatially Mn and Fe levels were associated with a well-defined heavy industrial area that includes large iron- and steel-making operations; Cu and Pb were associated with both the industrial and high-volume traffic areas, while Zn tended to be more associated with high-volume traffic areas. The potential bioavailability of the metals, based on the sum of chemical fractions 1 (exchangeable) and 2 (carbonate-bound), decreased in order: Zn > Cd > Mn > Pb > Cu > Fe. Based on aquatic sediment quality guidelines, there is some concern regarding the potential impact of the street sediment when runoff reaches receiving waters. Conclusions: It is possible that a combination of BMPs, including street sweeping and constructed wetlands, could help to reduce street sediment impact on environmental quality in the Hamilton region. The data presented here would be important in developing and optimizing the design of these BMPs. (orig.)
Biskup, B.; Maszl, C.; Breilmann, W.; Held, J.; Böke, M.; Benedikt, J.; von Keudell, A.
2018-03-01
High power impulse magnetron sputtering (HiPIMS) discharges are an excellent tool for deposition of thin films with superior properties. By adjusting the plasma parameters, an energetic metal and reactive species growth flux can be controlled. This control requires, however, a quantitative knowledge of the ion-to-neutral ratio in the growth flux and of the ion energy distribution function to optimize the deposited energy per incorporated atom in the film. This quantification is performed by combining two diagnostics, a quartz crystal microbalance (QCM) combined with an ion-repelling grid system (IReGS) to discriminate ions versus neutrals and a HIDEN EQP plasma monitor to measure the ion energy distribution function (IEDF). This approach yields the ionized metal flux fraction (IMFF) as the ionization degree in the growth flux. This is correlated to the plasma performance recorded by time resolved ICCD camera measurements, which allow to identify the formation of pronounced ionization zones, so called spokes, in the HiPIMS plasma. Thereby an automatic technique was developed to identify the spoke mode number. The data indicates two distinct regimes with respect to spoke formation that occur with increasing peak power, a stochastic regime with no spokes at low peak powers followed by a regime with distinct spokes at varying mode numbers at higher peak powers. The IMFF increases with increasing peak power reaching values of almost 80% at very high peak powers. The transition in between the two regimes coincides with a pronounced change in the IMFF. This change indicates that the formation of spokes apparently counteracts the return effect in HiPIMS. Based on the IMFF and the mean energy of the ions, the energy per deposited atom together with the overall energy flux onto the substrate is calculated. This allows us to determine an optimum for the peak power density around 0.5 kW cm-2 for chromium HiPIMS.
LI, R.; Shen, X.; Li, Y. H.; Chai, M. W.; Qiu, G. Y.
2015-12-01
Overlying water, sediment, rhizosphere sediment and mangrove seedlings in Futian mangrove forest were analyzed for heavy metals. The results showed that mangrove plant acidified sediment and increased organic matter contents. Except for chromium (Cr), nickel (Ni) and copper (Cu) in Aegiceras corniculatum sediment, heavy metals in all sediments were higher than in overlying water, rhizosphere sediment and mangrove root. Heavy metals in Avicennia marina sediments were higher than other sediments. The lower heavy metal biological concentration factors (BCFs) and translocation factors (TFs) indicated that mangrove plant adopted exclusion strategy. The geo-accumulation index, potential ecological risk index and risk assessment code (RAC) demonstrated that heavy metals have posed a considerable ecological risk, especially for cadmium (Cd). Heavy metals (Cr, Ni, Cu and Cd) mainly existed in the reducible fractions. The RAC values of heavy metals indicated that heavy metals have posed a considerable ecological risk to the biota, especially for Cd. These findings provide actual heavy metal accumulations in sediment-plant ecosystems in mangrove forest, being important in designing the long-term management and conservation policies for managers of mangrove forest.
Forest, Valérie; Vergnon, Jean-Michel; Guibert, Cyril; Bitounis, Dimitrios; Leclerc, Lara; Sarry, Gwendoline; Pourchez, Jérémie
Mineralogical analyses of clinical samples have been proved useful to identify causal relationship between exposure to airborne particles and pulmonary diseases. The most striking example is asbestosis where the assessment of asbestos bodies in patient lung samples has allowed defining values specific of pathologies. However, this type of analyses only considers the micro-sized fraction of the particles, neglecting the specific impact of nano-sized particles which have been otherwise shown to be reactive and able to induce biological effects. Similarly, in nanotoxicology, the mineralogical analysis of pulmonary fluids could be used as an indicator of exposure to inhaled nanoparticles and could help investigations on the relationship between exposure to these nanoparticles and lung diseases. We designed this study first to demonstrate the technical feasibility of this approach, then to get a clear picture of the metals present, and in what form, in patient lungs and finally to determine if indeed it is worth investigating separately the micro, sub-micro and nano fractions. Broncho-alveolar lavages were recovered from 100 patients suffering from interstitial lung diseases. A protocol was specifically developed to isolate three fractions containing respectively microparticles, sub-microparticles and nanoparticles with ions. The metal content in each fraction was qualitatively and quantitatively characterized. Results showed significant differences between the three fractions in terms of metal load confirming that the separate analysis of the fractions is relevant. It also means that the assessment of the micro-sized fraction alone, as commonly done in clinical practice, only gives a partial view of the mineralogical analysis.
A simple scheme to determine potential aquatic metal toxicity from mining wastes
Wildeman, T.R.; Smith, K.S.; Ranville, J.F.
2007-01-01
A decision tree (mining waste decision tree) that uses simple physical and chemical tests has been developed to determine whether effluent from mine waste material poses a potential toxicity threat to the aquatic environment. For the chemical portion of the tree, leaching tests developed by the United States Geological Survey, the Colorado Division of Minerals and Geology (Denver, CO), and a modified 1311 toxicity characteristic leaching procedure (TCLP) test of the United States Environmental Protection Agency have been extensively used as a surrogate for readily available metals that can be released into the environment from mining wastes. To assist in the assessment, element concentration pattern graphs (ECPG) are produced that compare concentrations of selected groups of elements from the three leachates and any water associated with the mining waste. The MWDT makes a distinction between leachates or waters with pH less than or greater than 5. Generally, when the pH values are below 5, the ECPG of the solutions are quite similar, and potential aquatic toxicity from cationic metals, such as Pb, Cu, Zn, Cd, and Al, is assumed. Below pH 5, these metals are mostly dissolved, generally are not complexed with organic or inorganic ligands, and hence are more bioavailable. Furthermore, there is virtually no carbonate alkalinity at pH less than 5. All of these factors promote metal toxicity to aquatic organisms. On the other hand, when the pH value of the water or the leachates is above 5, the ECPG from the solutions are variable, and inferred aquatic toxicity depends on factors in addition to the metals released from the leaching tests. Hence, leachates and waters with pH above 5 warrant further examination of their chemical composition. Physical ranking criteria provide additional information, particularly in areas where waste piles exhibit similar chemical rankings. Rankings from physical and chemical criteria generally are not correlated. Examples of how this
Pelfrêne, Aurélie; Kleckerová, Andrea; Pourrut, Bertrand; Nsanganwimana, Florien; Douay, Francis; Waterlot, Christophe
2015-02-01
The in situ stabilization of metals in soils using plants with great biomass value is a promising, cost-effective, and ecologically friendly alternative to manage metal-polluted sites. The goal of phytostabilization is to reduce the bioavailable concentrations of metals in polluted soil and thus reduce the risk to the environment and human health. In this context, this study aimed at evaluating Miscanthus × giganteus efficiency in phytostabilizing metals on three contaminated agricultural sites after short-term exposure under greenhouse conditions and after long-term exposure under field conditions. Particular attention was paid to the influence of Miscanthus cultivation on (i) Cd, Pb, and Zn fractionation using sequential extractions and (ii) metal bioaccessibility using an in vitro gastrointestinal digestion test. Data gave evidence of (i) different behaviors between the greenhouse and the field; (ii) metal redistribution in soils induced by Miscanthus culture, more specifically under field conditions; (iii) higher environmental availability for Cd than for Pb and Zn was found in both conditions; and (iv) overall, a higher bioaccessible fraction for Pb (about 80 %) and Cd (65-77 %) than for Zn (36-52 %) was recorded in the gastric phase, with a sharp decrease in the intestinal phase (18-35 % for Cd, 5-30 % for Pb, and 36-52 % for Zn). Compared to soils without culture, the results showed that phytostabilization using Miscanthus culture provided evidence for substantial effects on oral bioaccessibility of Cd, Pb, and Zn.
Liu, Hou-Chun; You, Chen-Feng; Huang, Bor-Jiun; Huh, Chih-An
2013-08-15
Two marine sediment cores from offshore mid-western Taiwan were subsampled and pre-treated using a sequential extraction procedure to separate carbonate and reducible fractions. Aliquots of these extracts were analyzed to determine their chemical composition to evaluate the geochemical processes responsible for heavy metal distribution and accumulation in the coastal environment. Our data demonstrate that sedimentation rates derived from excess (210)Pb associated with metal fluxes show large increases circa A.D. 1990. A well-synchronized increase in metal flux in both geochemical fractions was found and validated by Pearson's correlation. Principal component analysis revealed the heavy metal fluxes to be highly correlated with the sediment deposition rate, with metal contamination potentially driven by a sole contributor. This study emphasizes the changes in sedimentation rate is potentially caused by activities associated with the inland economic development during this time, rather than by raising heavy metal pollution dominated the accumulation offshore mid-western Taiwan. Copyright © 2013 Elsevier Ltd. All rights reserved.
Wallace, W.G.; Lee, B.-G.; Luoma, S.N.
2003-01-01
Many aspects of metal accumulation in aquatic invertebrates (i.e. toxicity, tolerance and trophic transfer) can be understood by examining the subcellular partitioning of accumulated metal. In this paper, we use a compartmentalization approach to interpret the significance of metal, species and size dependence in the subcellular partitioning of Cd and Zn in the bivalves Macoma balthica and Potamocorbula amurensis. Of special interest is the compartmentalization of metal as metal-sensitive fractions (MSF) (i.e. organelles and heat-sensitive proteins, termed 'enzymes' hereafter) and biologically detoxified metal (BDM) (i.e. metallothioneins [MT] and metal-rich granules [MRG]). Clams from San Francisco Bay, CA, were exposed for 14 d to seawater (20??? salinity) containing 3.5 ??g l-1 Cd and 20.5 ??g l-1 Zn, including 109Cd and 65Zn as radiotracers. Uptake was followed by 21 d of depuration. The subcellular partitioning of metal within clams was examined following exposure and loss. P. amurensis accumulated ???22x more Cd and ???2x more Zn than M. balthica. MT played an important role in the storage of Cd in P. amurensis, while organelles were the major site of Zn accumulation. In M. balthica, Cd and Zn partitioned similarly, although the pathway of detoxification was metal-specific (MRG for Cd; MRG and MT for Zn). Upon loss, M. balthica depurated ???40% of Cd with Zn being retained; P. amurensis retained Cd and depurated Zn (???40%). During efflux, Cd and Zn concentrations in the MSF compartment of both clams declined with metal either being lost from the animal or being transferred to the BDM compartment. Subcellular compartmentalization was also size-dependent, with the importance of BDM increasing with clam size; MSF decreased accordingly. We hypothesized that progressive retention of metal as BDM (i.e. MRG) with age may lead to size dependency of metal concentrations often observed in some populations of M. balthica.
Singh, Jiwan; Yang, Jae-Kyu; Chang, Yoon-Young
2016-02-01
Automobile shredder residue (ASR) fraction (size <0.25mm) can be considered as hazardous due to presence of high concentrations of heavy metals. Hydrogen peroxide combined with nitric acid has been used for the recovery of heavy metals (Zn, Cu, Mn, Fe, Ni, Pb, Cd and Cr) from the fine fraction of ASR. A sequential extraction procedure has also been used to determine the heavy metal speciation in the fine fraction of ASR before and after treatment. A risk analysis of the fine fraction of ASR before and after treatment was conducted to assess the bioavailability and eco-toxicity of heavy metals. These results showed that the recovery of heavy metals from ASR increased with an increase in the hydrogen peroxide concentration. A high concentration of heavy metals was found to be present in Cbio fractions (the sum of the exchangeable and carbonate fractions) in the fine fraction of ASR, indicating high toxicity risk. The Cbio rate of all selected heavy metals was found to range from 8.6% to 33.4% of the total metal content in the fine fraction of ASR. After treatment, Cbio was reduced to 0.3-3.3% of total metal upon a treatment with 2.0% hydrogen peroxide. On the basis of the risk assessment code (RAC), the environmental risk values for heavy metals in the fine fraction of ASR reflect high risk/medium risk. However, after treatment, the heavy metals would be categorized as low risk/no risk. The present study concludes that hydrogen peroxide combined with nitric acid is a promising treatment for the recovery and reduction of the eco-toxicity risk of heavy metals in ASR. Copyright © 2015 Elsevier Ltd. All rights reserved.
Elardo, S. M.; Shahar, A.
2015-12-01
There are numerous studies that show well-resolved Fe isotope fractionations in igneous materials from different planetary bodies. Potential explanations for these fractionations include a non-chondritic bulk planetary Fe isotopic composition, and equilibrium fractionation between Fe-alloys or minerals and silicate melts during planetary differentiation, mantle melting, or fractional crystallization. This is further complicated by the fact that these processes are not mutually exclusive, making the interpretation of Fe isotope data a complex task. Here we present new experimental results investigating the effect of C on Fe isotope fractionation between molten peridotite and an Fe-alloy. Experiments were conducted at 1 GPa and 1850° C for 0.5 - 3 hours on a mixture of an 54Fe-spiked peridotite and Fe-metal with and without Ni metal in an end-loaded piston cylinder at the Geophysical Laboratory. Carbon saturation was achieved with a graphite capsule, and resulted in C contents of the Fe-alloy in our experiments ranging from 3.8 - 4.9 wt. %. The metal and silicate phases from half of each experiment were separated manually and dissolved in concentrated acids. Iron was separated from matrix elements by anion exchange chromatagraphy. Iron-isotopic compositions were determined with the Nu Plasma II MC-ICP-MS at GL. The other half of each experiment was used for quantitative microbeam analysis. Equilibrium was assessed with a time series and the three-isotope exchange method. The Ni-free experiments resulted in no resolvable Fe isotope fractionation between the Fe-C-alloy and molten silicate. This is in contrast to the results of Shahar et al. (2015) which showed a fractionation for Δ57Fe of ~0.18 ‰ between a peridotite and an Fe-alloy with a similar S abundance to C in these experiments. The one experiment thus far that contained Ni (~4 wt. % in the alloy) showed a resolvable fractionation between the Fe-Ni-C alloy and silicate of ~0.10 ‰. Shahar et al. found a
Prediction of size-fractionated airborne particle-bound metals using MLR, BP-ANN and SVM analyses.
Leng, Xiang'zi; Wang, Jinhua; Ji, Haibo; Wang, Qin'geng; Li, Huiming; Qian, Xin; Li, Fengying; Yang, Meng
2017-08-01
Size-fractionated heavy metal concentrations were observed in airborne particulate matter (PM) samples collected from 2014 to 2015 (spanning all four seasons) from suburban (Xianlin) and industrial (Pukou) areas in Nanjing, a megacity of southeast China. Rapid prediction models of size-fractionated metals were established based on multiple linear regression (MLR), back propagation artificial neural network (BP-ANN) and support vector machine (SVM) by using meteorological factors and PM concentrations as input parameters. About 38% and 77% of PM 2.5 concentrations in Xianlin and Pukou, respectively, were beyond the Chinese National Ambient Air Quality Standard limit of 75 μg/m 3 . Nearly all elements had higher concentrations in industrial areas, and in winter among the four seasons. Anthropogenic elements such as Pb, Zn, Cd and Cu showed larger percentages in the fine fraction (ø≤2.5 μm), whereas the crustal elements including Al, Ba, Fe, Ni, Sr and Ti showed larger percentages in the coarse fraction (ø > 2.5 μm). SVM showed a higher training correlation coefficient (R), and lower mean absolute error (MAE) as well as lower root mean square error (RMSE), than MLR and BP-ANN for most metals. All the three methods showed better prediction results for Ni, Al, V, Cd and As, whereas relatively poor for Cr and Fe. The daily airborne metal concentrations in 2015 were then predicted by the fully trained SVM models and the results showed the heaviest pollution of airborne heavy metals occurred in December and January, whereas the lightest pollution occurred in June and July. Copyright © 2017 Elsevier Ltd. All rights reserved.
Moturi, M C Z; Rawat, M; Subramanian, V
2004-07-01
Solid waste samples were collected from five small-scale industrial sites in the National Capital Territory (NCT) of Delhi. These industrial sites represent the regional spread of the industrial belt in the NCT of Delhi. Solid waste samples were digested using aqua-regia and HF in air tight teflon bombs for the quantitative analysis of heavy metals (Hg, Pb, Cd, Mn, Fe, Ni, Cu and Zn) by GBC model 902 atomic absorption spectrophotometer. Hg was analysed using hydrid generator attachment. Beside this sequential extraction was used to fractionate five heavy metals (Pb, Ni, Cd, Cu and Zn) into six operationally defined phases, viz. water soluble, exchangeable, carbonate-bound, Fe-Mn oxides, organic-bound and residual fractions to ascertain the relative mobility of these metals. The result obtained showed metal concentration to be in the range of Hg 0.42-2.3; Pb 23-530; Cd 014-224; Mn 494-19 964; Fe 35 684-233 119; Ni 192-1534; Cu 3065-10 144 and Zn 116-23 321 (all units in mg kg(-1)) in all the industrial areas studied. The fractionated toxic metals like Pb, Ni and Cd were observed to be in the range of 25-35, 15-50 and 40-50%, respectively, in mobile or bio-available fractions of solid waste. As this waste is often disposed-off by the roadsides, low lying areas, abandoned quarries or in landfill sites which are often not properly planned, thus posing potential risk to ground and surface water quality to millions of people living downstream.
The role of carbon dioxide in the transport and fractionation of metals by geological fluids
Kokh, Maria A.; Akinfiev, Nikolay N.; Pokrovski, Gleb S.; Salvi, Stefano; Guillaume, Damien
2017-01-01
depletion in metamorphic gold deposits formed by CO2-rich fluids. The transport of gold is unfavorable in the presence of CO2 only in S-rich (>0.5 wt% S) fluids in which Au forms the negatively charged Au(HS)2- and Au(HS)S3- complexes. By contrast, it is only weakly affected in S-poor (50 wt% CO2), the capacity of such fluids to transport gold (up to 100s ppb Au) remains comparable to that of aqueous fluids. These findings are in agreement with analyses of natural fluid inclusions in metamorphic deposits. In more saline oxidizing and S-rich fluids such as those in magmatic porphyry Cu-Au deposits, the Fe, Cu, and Au solubilities in the presence of CO2 decrease by ∼1 order of magnitude with CO2 increasing to 20-30 wt%, following the decrease in the stability of their dominant charged species (FeCl42-, CuCl2-, Au(HS)2- and Au(HS)S3-), but stay almost constant at higher CO2 contents (30-70 wt%) as controlled by the neutral species (FeCl20, Cu(HS)0 and Au(HS)0). Such solubility trends suggest a new potential trigger of ore precipitation in porphyry systems by CO2 pulses from the magmatic chamber, which may operate along with commonly admitted depositional mechanisms such as cooling, vapor-brine immiscibility, and water-rock interaction. The direct effect of CO2 on the mobility of Pt and Mo, metals that likely form hydrogen sulfide and oxy-hydroxide complexes, respectively, is expected to be weak in most settings. Among the studied elements, Sn is the only one whose solubility may be favored at high CO2 content (>20 wt%) due to carbonate complexing. This study demonstrates, for the first time, that, contrary to common belief, the presence of CO2 in a supercritical fluid may lead to enhanced mobility or, on contrary, to massive precipitation of some metals, depending on salinity and sulfur content, and, more generally, to significant fractionations between different metals.
Faheem, Muhammad; Heyden, Andreas
2014-08-12
We report the development of a quantum mechanics/molecular mechanics free energy perturbation (QM/MM-FEP) method for modeling chemical reactions at metal-water interfaces. This novel solvation scheme combines planewave density function theory (DFT), periodic electrostatic embedded cluster method (PEECM) calculations using Gaussian-type orbitals, and classical molecular dynamics (MD) simulations to obtain a free energy description of a complex metal-water system. We derive a potential of mean force (PMF) of the reaction system within the QM/MM framework. A fixed-size, finite ensemble of MM conformations is used to permit precise evaluation of the PMF of QM coordinates and its gradient defined within this ensemble. Local conformations of adsorbed reaction moieties are optimized using sequential MD-sampling and QM-optimization steps. An approximate reaction coordinate is constructed using a number of interpolated states and the free energy difference between adjacent states is calculated using the QM/MM-FEP method. By avoiding on-the-fly QM calculations and by circumventing the challenges associated with statistical averaging during MD sampling, a computational speedup of multiple orders of magnitude is realized. The method is systematically validated against the results of ab initio QM calculations and demonstrated for C-C cleavage in double-dehydrogenated ethylene glycol on a Pt (111) model surface.
Sakan, Sanja; Popović, Aleksandar; Anđelković, Ivan; Đorđević, Dragana
2016-06-01
The sequential extraction procedure of the European Community Bureau of Reference (BCR) was applied for the fractionation of Cd, Cr, Cu, Ni, Pb, Zn, Fe, Mn, and V in the Serbian river sediments. The aim of this paper was to describe a new approach in detection of anthropogenic elements in sediments, related to the Serbian river courses in order to assess their metal contamination. For sediment pollution evaluation, the risk assessment code (RAC) and the secondary phase enrichment factor (KSPEF) were used. Metal fractionation showed more easily mobilized forms predominant for copper, zinc, cadmium, manganese, and lead, which can be one of the indicators for anthropogenic source input. Chromium, nickel, iron, and vanadium found in the residual fraction indicate these metals may be an indicator for natural sources input. Based on RAC classification, results of sediments show no risk (Cr and V), low risk (Ni, Pb, and Fe), medium risk (Cu), high risk (Cd and Zn), and very high risk (Mn). The mean values of KSPEF were Cd > Cu > Zn > Ni > Mn > Pb > Fe > Cr > V, decreasing scale of no to moderately severe enrichment. The sediments were found to be contaminated by heavy metals to various extents, mostly Cd, Cu, and Zn. Research has shown the importance of KSPEF in quantifying degree of metal enrichment in sediments using results of sequential extraction. With the application of this factor, which is not frequently used in the scientific literature, the results obtained with sequential extraction can be used not only for assessment of mobility but also to quantify the metal pollution.
Feizi, Morteza; Jalali, Mohsen; Renella, Giancarlo
2018-02-05
We comparatively assessed the effect of modified clays (MCs) (zeolite and bentonite) and nanoparticles (NPs) (ZnO and MgO) on the distribution of cadmium (Cd), copper (Cu), nickel (Ni) and zinc (Zn) fractions in a light-textured soil amended with five sewage sludges (SSs) differed in chemical properties during a 92-day incubation experiment in the laboratory. Results indicated that presence of adsorbents and incubation time were critical parameters in stabilizing metals in SS-amended soil. The adsorbents that significantly decreased the easily soluble and exchangeable of metals in SS-amended soil (rate 2%) were bentonite, ZnO and MgO for Cd and Cu, ZnO and MgO for Ni, and bentonite and MgO for Zn. The calculated mobility factor of the metals at five incubation times (5, 15, 29, 57 and 92days) was found in the range of 34.7-51.8 for Cd, 16.7-20.0 for Cu, 15.0-27.7 for Ni, and 35.3-40.7 for Zn indicating a higher mobility of Cd. The addition of MCs and NPs decreased the available fraction of metals, and among them, we suggest bentonite and MgO as novel, promising and feasible adsorbents with the unique characteristics in ameliorating the toxic effects of metals by converting their form from labile to non-labile phases in the SS-amended soil. Copyright © 2017 Elsevier B.V. All rights reserved.
Li, Ruili; Chai, Minwei; Qiu, Guo Yu
2016-01-01
Overlying water, sediment, rhizosphere sediment and mangrove seedlings in the Futian mangrove forest were analyzed for heavy metals. The results showed that mangrove plant acidified sediment and increased organic matter contents. Except for chromium (Cr), nickel (Ni) and copper (Cu) in Aegiceras corniculatum sediment, heavy metals in all sediments were higher than in overlying water, rhizosphere sediment and mangrove root. Heavy metals in Avicennia marina sediments were higher than other sediments. The lower heavy metal biological concentration factors (BCFs) and translocation factors (TFs) indicated that mangrove plant adopted exclusion strategy. The geo-accumulation index, potential ecological risk index and risk assessment code (RAC) demonstrated that heavy metals have posed a considerable ecological risk, especially for cadmium (Cd). Heavy metals (Cr, Ni, Cu and Cd) mainly existed in the reducible fractions. These findings provide actual heavy metal accumulations in sediment-plant ecosystems in mangrove forest, being important in designing the long-term management and conservation policies for managers of mangrove forest. PMID:26800267
Díaz, Alfredo; Arnedo, Rebeca; Céspedes-Sánchez, Raquel; Devesa, Ricard; Martin-Alonso, Jordi
2012-01-01
A performance study of diffusive gradients in thin films (DGT) and inductively coupled plasma optical emission spectrometry (ICP-OES) was applied for the monitoring of the labile fraction of metals Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, in Sant Joan Despí Drinking Water Treatment Plant located in the South of Barcelona's Metropolitan Area (Spain). The DWTP monitoring protocol was optimized by working for 1 day of deployment (24 h) with the DGT device in contact with both treated and river water matrixes. Additionally, it was demonstrated that an increase in the deployment time of 1 week did not decrease the evaluated concentrations of the studied metals. The quality parameters of the DGT device and ICP-OES determination, such as limit of quantification, accuracy expressed as relative error (%) and reproducibility expressed as relative standard deviation, were evaluated. Good results were obtained for all the metals in ultrapure water; limits of quantification ranged from 1.5 μg L( - 1) for cadmium to 28 μg L( - 1) for zinc when deployment time of 24 h was used and from 0.2 μg L( - 1) for cadmium to 4 μg L( - 1) for zinc when this time was increased by 1 week. Accuracy and precisions lower than or equal to 10% were obtained at a parametric concentration value of the metals regulated in the European Drinking Water Guidelines (98/83/EC). DGT deployment was tested in river and treated water, and good results were obtained for Cd, Ni, Co and Zn, whereas for the other metals, a continuous control of their metallic labile fractions was monitored. Therefore, DGT device allows the continuous monitoring of the labile metal species in a drinking water treatment plant.
Wen, Fang; Hou, Hong; Yao, Na; Yan, Zengguang; Bai, Liping; Li, Fasheng
2013-01-01
A laboratory repacked soil-leaching column experiment was conducted to study the effects of simulated acid rain or EDTA by themselves or in combination, on migration and chemical speciation distribution of Pb and its alternative rare metals including Ag, Bi, In, Sb, and Sn. Experimental results demonstrate that leaching with simulated acid rain promoted the migration of Bi, In and Pb, and their migration reached down to 8 cm in the soil profile, no enhancement of Sb, Ag or Sn migration was observed. Addition of EDTA significantly enhanced the migration of all six metals, especially Bi, In and Pb. The migration of metals was in the order Pb>Bi>In>Sb>Sn>Ag. The individual and combined effects of acid rain and EDTA increased the environmental risk of metals, by increasing the soluble content of metals in soil solutions and the relative distribution of the exchangeable fraction. Leaching risks of Bi, In and Pb were higher than other three metals. Copyright © 2012 Elsevier Ltd. All rights reserved.
Li, Fei; Xiao, Minsi; Zhang, Jingdong; Liu, Chaoyang; Qiu, Zhenzhen; Cai, Ying
2018-01-26
Spatial concentrations and chemical fractions of heavy metals (Cr, Cu, Pb, Zn and Cd) in 16 sampling sites from the Honghu Lake were investigated using an atomic absorption spectrophotometer and optimized BCR (the European Community Bureau of Reference) three-stage extraction procedure. Compared with the corresponding probable effect levels (PELs), adverse biological effects of the studied five sediment metals decreased in the sequence of Cr > Cu > Zn > Pb > Cd. Geo-accumulation index ( I geo ) values for Cr, Cu, Pb and Zn in each sampling site were at un-contamination level, while the values for Cd varied from un-contamination level to moderate contamination level. Spatially, the enrichment degree of Cd in lower part of the South Lake, the west part of the North Lake and the outlet were higher than the other parts of Honghu Lake. For metal chemical fractions, the proportions of the acid-extractable fraction of five metal contents were in the descending order: Cd, Cu, Zn, Pb and Cr. Cd had the highest bioaccessibility. Being the above indexes focused always on heavy metals' total content or chemical fraction in deterministic assessment system, which may confuse decision makers, the fuzzy comprehensive risk assessment method was established based on PEI (Potential ecological risk index), RAC (Risk assessment code) and fuzzy theory. Average comprehensive risks of heavy metals in sediments revealed the following orders: Cd (considerable risk) > Cu (moderate risk) > Zn (low risk) > Pb > Cr. Thus, Cd and Cu were determined as the pollutants of most concern. The central part of South Honghu Lake (S4, S5, S6, S9, S12 and S14), east part of the North Honghu Lake (S1) and outlet of outlet of the Honghu Lake (S10) were recommended as the priority control areas. Specifically, it is necessary to pay more attention to S1, S4, S5, S6, S9 and S16 when decision making for their calculated membership values (probabilities) of adjacent risk levels quite close.
Andre, Jane; Charnock, John; Stürzenbaum, Stephen R; Kille, Peter; Morgan, A John; Hodson, Mark E
2009-09-01
Predicting metal bioaccumulation and toxicity in soil organisms is complicated by site-specific biotic and abiotic parameters. In this study we exploited tissue fractionation and digestion techniques, combined with X-ray absorption spectroscopy (XAS), to investigate the whole-body and subcellular distributions, ligand affinities, and coordination chemistry of accumulated Pb and Zn in field populations of the epigeic earthworm Lumbricus rubellus inhabiting three contrasting metalliferous and two unpolluted soils. Our main findings were (i) earthworms were resident in soils with concentrations of Pb and Zn ranging from 1200 to 27,000 mg kg(-1) and 200 to 34,000 mg kg(-1), respectively; (ii) Pb and Zn primarily accumulated in the posterior alimentary canal in nonsoluble subcellular fractions of earthworms; (iii) site-specific differences in the tissue and subcellular partitioning profiles of populations were observed, with earthworms from a calcareous site partitioning proportionally more Pb to their anterior body segments and Zn to the chloragosome-rich subcellular fraction than their acidic-soil inhabiting counterparts; (iv) XAS indicated that the interpopulation differences in metal partitioning between organs were not accompanied by qualitative differences in ligand-binding speciation, because crystalline phosphate-containing pyromorphite was a predominant chemical species in the whole-worm tissues of all mine soil residents. Differences in metal (Pb, Zn) partitioning at both organ and cellular levels displayed by field populations with protracted histories of metal exposures may reflect theirinnate ecophysiological responses to essential edaphic variables, such as Ca2+ status. These observations are highly significant in the challenging exercise of interpreting holistic biomarker data delivered by "omic" technologies.
Xiao, Minsi; Zhang, Jingdong; Liu, Chaoyang; Qiu, Zhenzhen; Cai, Ying
2018-01-01
Spatial concentrations and chemical fractions of heavy metals (Cr, Cu, Pb, Zn and Cd) in 16 sampling sites from the Honghu Lake were investigated using an atomic absorption spectrophotometer and optimized BCR (the European Community Bureau of Reference) three-stage extraction procedure. Compared with the corresponding probable effect levels (PELs), adverse biological effects of the studied five sediment metals decreased in the sequence of Cr > Cu > Zn > Pb > Cd. Geo-accumulation index (Igeo) values for Cr, Cu, Pb and Zn in each sampling site were at un-contamination level, while the values for Cd varied from un-contamination level to moderate contamination level. Spatially, the enrichment degree of Cd in lower part of the South Lake, the west part of the North Lake and the outlet were higher than the other parts of Honghu Lake. For metal chemical fractions, the proportions of the acid-extractable fraction of five metal contents were in the descending order: Cd, Cu, Zn, Pb and Cr. Cd had the highest bioaccessibility. Being the above indexes focused always on heavy metals’ total content or chemical fraction in deterministic assessment system, which may confuse decision makers, the fuzzy comprehensive risk assessment method was established based on PEI (Potential ecological risk index), RAC (Risk assessment code) and fuzzy theory. Average comprehensive risks of heavy metals in sediments revealed the following orders: Cd (considerable risk) > Cu (moderate risk) > Zn (low risk) > Pb > Cr. Thus, Cd and Cu were determined as the pollutants of most concern. The central part of South Honghu Lake (S4, S5, S6, S9, S12 and S14), east part of the North Honghu Lake (S1) and outlet of outlet of the Honghu Lake (S10) were recommended as the priority control areas. Specifically, it is necessary to pay more attention to S1, S4, S5, S6, S9 and S16 when decision making for their calculated membership values (probabilities) of adjacent risk levels quite close. PMID:29373483
Valdez Cerda, Enrique; Hinojosa Reyes, Laura; Alfaro Barbosa, Juan Manuel; Elizondo-Martinez, Perla; Acuña-Askar, Karim
2011-07-01
The prevalence of heavy metal pollution and mobility of both Pb and Cd was investigated in street dust samples from the Metropolitan Area of Monterrey (MAM) in northern Mexico. Street dust samples from 30 selected sites were analysed for their content of Zn, Cd, Pb, Cr and Ni after digestion according to U.S. EPA Method 3051. Multivariate analysis including correlation coefficient analysis, Principal Component Analysis and Cluster Analysis was used to analyse the data and identify possible sources of these heavy metals. Compared with background values, elevated concentrations of Pb (300 mg kg(-1)), Cd (7.6 mg kg(-1)) and Cr (78 mg kg(-1)) were observed in street dust of MAM. Based on multivariate statistical approaches, the studied elements were classified in three main sources: (1) Cr, Ni and Zn mainly derived from industrial activities; (2) Cd originating from traffic-related activities; and (3) Pb associated with vehicular emissions. A sequential extraction procedure using the Tessier method was applied to evaluate the mobility of Pb and Cd in street dust. The majority of Pb was associated with the residual fraction followed by the carbonate fraction. The majority of Cd was associated with the residual fraction. These results indicated that the mobility was higher in Pb (26%) compared with Cd (11%), posing a potential risk to the environment.
International Nuclear Information System (INIS)
Udovic, Metka; Lestan, Domen
2007-01-01
The effect of two earthworm species, Lumbricus rubellus and Eisenia fetida, on the fractionation/bioavailability of Pb and Zn before and after soil leaching with EDTA was studied. Four leaching steps with total 12.5 mmol kg -1 EDTA removed 39.8% and 6.1% of Pb and Zn, respectively. EDTA removed Pb from all soil fractions fairly uniformly (assessed using sequential extractions). Zn was mostly present in the chemically inert residual soil fraction, which explains its poor removal. Analysis of earthworm casts and the remainder of the soil indicated that L. rubellus and E. fetida actively regulated soil pH, but did not significantly change Pb and Zn fractionation in non-remediated and remediated soil. However, the bioavailability of Pb (assessed using Ruby's physiologically based extraction test) in E. fetida casts was significantly higher than in the bulk of the soil. In remediated soil the Pb bioavailability in the simulated stomach phase increased by 5.1 times. - Earthworm activity increases heavy metal bioavailability in soil before and after remediation
Energy Technology Data Exchange (ETDEWEB)
Udovic, Metka [Agronomy Department, Centre for Soil and Environmental Science, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana (Slovenia); Lestan, Domen [Agronomy Department, Centre for Soil and Environmental Science, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana (Slovenia)]. E-mail: domen.lestan@bf.uni-lj.si
2007-07-15
The effect of two earthworm species, Lumbricus rubellus and Eisenia fetida, on the fractionation/bioavailability of Pb and Zn before and after soil leaching with EDTA was studied. Four leaching steps with total 12.5 mmol kg{sup -1} EDTA removed 39.8% and 6.1% of Pb and Zn, respectively. EDTA removed Pb from all soil fractions fairly uniformly (assessed using sequential extractions). Zn was mostly present in the chemically inert residual soil fraction, which explains its poor removal. Analysis of earthworm casts and the remainder of the soil indicated that L. rubellus and E. fetida actively regulated soil pH, but did not significantly change Pb and Zn fractionation in non-remediated and remediated soil. However, the bioavailability of Pb (assessed using Ruby's physiologically based extraction test) in E. fetida casts was significantly higher than in the bulk of the soil. In remediated soil the Pb bioavailability in the simulated stomach phase increased by 5.1 times. - Earthworm activity increases heavy metal bioavailability in soil before and after remediation.
International Nuclear Information System (INIS)
Xiao, Rong; Bai, Junhong; Lu, Qiongqiong; Zhao, Qingqing; Gao, Zhaoqin; Wen, Xiaojun; Liu, Xinhui
2015-01-01
The effect of reclamation on heavy metal concentrations and the ecological risks in ditch wetlands (DWs) and riparian wetlands (RWs) across a 100-year chronosequence in the Pearl River Estuary of China was investigated. Concentrations of 4 heavy metals (Cd, Cu, Pb, and Zn) in soil and plant samples, and sequential extracts of soil samples were determined, using inductively coupled plasma atomic absorption spectrometry. Results showed that heavy metal concentrations were higher in older DW soils than in the younger ones, and that the younger RW soils contained higher heavy metal concentrations compared to the older ones. Although the increasing tendency of heavy metal concentrations in soil was obvious after wetland reclamation, the metals Cu, Pb, and Zn exhibited low or no risks to the environment based on the risk assessment code (RAC). Cd, on the other hand, posed a medium or high risk. Cd, Pb, and Zn were mainly bound to Fe–Mn oxide, whereas most of Cu remained in the residual phase in both ditch and riparian wetland soils, and the residual proportions generally increased with depth. Bioconcentration and translocation factors for most of these four heavy metals significantly decreased in the DWs with older age (p < 0.05), whereas they increased in the RWs with younger age (p < 0.05). The DW soils contained higher concentrations of heavy metals in the organic fractions, whereas there were more carbonate and residual fractions in the RW soils. The non-bioavailable fractions of Cu and Zn, and the organic-bound Cd and Pb significantly inhibited plant growth. - Highlights: • Heavy metals in ditch wetland accumulated with increasing reclamation history. • Heavy metals exist in the Fe–Mn oxides and residual fractions in both wetlands. • Cd posed a medium to high environmental risk while low risk for other metals. • Long reclamation history caused lower BCFs and TFs in DWs and higher levels in RWs. • RW soils contained more heavy metals in the carbonate
Fornadel, Andrew P.; Spry, Paul G.; Haghnegahdar, Mojhgan A.; Schauble, Edwin A.; Jackson, Simon E.; Mills, Stuart J.
2017-04-01
The tellurium isotope compositions of naturally-occurring tellurides, native tellurium, and tellurites were measured by multicollector-inductively coupled plasma-mass spectrometry (MC-ICP-MS) and compared to theoretical values for equilibrium mass-dependent isotopic fractionation of representative Te-bearing species estimated with first-principles thermodynamic calculations. Calculated fractionation models suggest that 130/125Te fractionations as large as 4‰ occur at 100 °C between coexisting tellurates (Te VI) and tellurides (Te -II) or or native tellurium Te(0), and smaller, typically calaverite, krennerite) and (Au,Ag)2Te minerals (i.e., petzite, hessite). In general, heavyTe/lightTe is predicted to be higher for more oxidized species, and lower for reduced species. Tellurides in the system Au-Ag-Te and native tellurium analyzed in this study have values of δ130/125Te = -1.54‰ to 0.44‰ and δ130/125Te = -0.74‰ to 0.16‰, respectively, whereas those for tellurites (tellurite, paratellurite, emmonsite and poughite) range from δ130/125Te = -1.58‰ to 0.59‰. Thus, the isotopic composition for both oxidized and reduced species are broadly coincident. Calculations of per mil isotopic variation per amu for each sample suggest that mass-dependent processes are responsible for fractionation. In one sample of coexisting primary native tellurium and secondary emmonsite, δ130/125Te compositions were identical. The coincidence of δ130/125Te between all oxidized and reduced species in this study and the apparent lack of isotopic fractionation between native tellurium and emmonsite in one sample suggest that oxidation processes cause little to no fractionation. Because Te is predominantly transported as an oxidized aqueous phase or as a reduced vapor phase under hydrothermal conditions, either a reduction of oxidized Te in hydrothermal liquids or deposition of Te from a reduced vapor to a solid is necessary to form the common tellurides and native tellurium in
Bonnand, P.; Williams, H. M.; Parkinson, I. J.; Wood, B. J.; Halliday, A. N.
2016-02-01
We present new mass independent and mass dependent Cr isotope compositions for meteorites measured by double spike thermal ionisation mass spectrometry. Small differences in both mass independent 53Cr and 54Cr relative to the Bulk Silicate Earth are reported and are very similar to previously published values. Carbonaceous chondrites are characterised by an excess in 54Cr compared to ordinary and enstatite chondrites which make mass independent Cr isotopes a useful tool for distinguishing between meteoritic groups. Mass dependent stable Cr isotope compositions for the same samples are also reported. Carbonaceous and ordinary chondrites are identical within uncertainty with average δ53 Cr values of - 0.118 ± 0.040 ‰ and - 0.143 ± 0.074 ‰ respectively. The heaviest isotope compositions are recorded by an enstatite chondrite and a CO carbonaceous chondrite, both of which have relatively reduced chemical compositions implying some stable Cr isotope fractionation related to redox processes in the circumstellar disk. The average δ53 Cr values for chondrites are within error of the estimate for the Bulk Silicate Earth (BSE) also determined by double spiking. The lack of isotopic difference between chondritic material and the BSE provides evidence that Cr isotopes were not fractionated during core formation on Earth. A series of high-pressure experiments was also carried out to investigate stable Cr isotope fractionation between metal and silicate and no demonstrable fractionation was observed, consistent with our meteorites data. Mass dependent Cr isotope data for achondrites suggest that Cr isotopes are fractionated during magmatic differentiation and therefore further work is required to constrain the Cr isotopic compositions of the mantles of Vesta and Mars.
Koltun, G.F.; Helsel, Dennis R.
1986-01-01
Identical stream-bottom material samples, when fractioned to the same size by different techniques, may contain significantly different trace-metal concentrations. Precision of techniques also may differ, which could affect the ability to discriminate between size-fractioned bottom-material samples having different metal concentrations. Bottom-material samples fractioned to less than 0.020 millimeters by means of three common techniques (air elutriation, sieving, and settling) were analyzed for six trace metals to determine whether the technique used to obtain the desired particle-size fraction affects the ability to discriminate between bottom materials having different trace-metal concentrations. In addition, this study attempts to assess whether median trace-metal concentrations in size-fractioned bottom materials of identical origin differ depending on the size-fractioning technique used. Finally, this study evaluates the efficiency of the three size-fractioning techniques in terms of time, expense, and effort involved. Bottom-material samples were collected at two sites in northeastern Ohio: One is located in an undeveloped forested basin, and the other is located in a basin having a mixture of industrial and surface-mining land uses. The sites were selected for their close physical proximity, similar contributing drainage areas, and the likelihood that trace-metal concentrations in the bottom materials would be significantly different. Statistically significant differences in the concentrations of trace metals were detected between bottom-material samples collected at the two sites when the samples had been size-fractioned by means of air elutriation or sieving. Statistical analyses of samples that had been size fractioned by settling in native water were not measurably different in any of the six trace metals analyzed. Results of multiple comparison tests suggest that differences related to size-fractioning technique were evident in median copper, lead, and
Zhang, Guangliang; Bai, Junhong; Xiao, Rong; Zhao, Qingqing; Jia, Jia; Cui, Baoshan; Liu, Xinhui
2017-10-01
Rapid urbanization and reclamation processes in coastal areas have resulted in serious pollution to the aquatic environment. Less is known on the geochemical fractions and ecological risks in river sediment under various human activities pressures, which is essential for addressing the connections between heavy metal pollution and anthropogenic influences. River sediments were collected from different landscapes (i.e., urban, rural and reclamation areas) to investigate the impacts of urbanization and reclamation on the metallic pollution levels and ecological risks in the Pear River Estuary of China. Results showed that Cd, Zn and Cu with high total contents and geoaccumulation index (I geo ) were the primary metals in the Peal River sediments. Generally, urban river sediments, especially the surface sediment layer (0-10 cm), exhibited higher metallic pollution levels. As for geochemical fractions, reducible and residual fractions were the dominant forms for six determined metals. And the percentage of heavy metals bound to Fe-Mn oxides decreased with increasing soil depth but the reverse tendency was observed for residual fractions. Compared with rural river sediments, heavy metals were highly associated with the exchangeable and carbonate fractions in both urban and reclamation-affected river sediments, suggesting that anthropogenic activities mainly increased the active forms of metals. Approximately 80% of Cd existed in the non-residual fraction and posed medium to high ecological risk according to the risk assessment code (RAC) values. The redundancy analysis (RDA) revealed that both urbanization and reclamation processes would cause similar metallic characteristics, and sediment organic matter (SOC) might be the prominent influencing factor. Copyright © 2017 Elsevier Ltd. All rights reserved.
Bonding Form Analysis of Metals and Sulfur Fractionation in Methanol-Grown Anaerobic Granular Sludge
Veen, van der A.; Gonzalez Fermoso, F.; Lens, P.N.L.
2007-01-01
This study investigates the metal and sulfur bonding form distribution in mesophilic (30 °C, pH 7) methanol-grown anaerobic granular sludge from upflow anaerobic sludge bed reactors operating at an organic loading rate of 3.8 g CH3OH-COD/L d. This was achieved by applying a modified Tessier
Fractionation and leaching of heavy metals in soils amended with a new biochar nanocomposite
Arabyarmohammadi, Hoda; Darban, Ahmad Khodadadi; Zee, van der Sjoerd E.A.T.M.; Abdollahy, Mahmoud; Ayati, Bita
2018-01-01
In this study, surface soils of the Bama Pb-Zn mine-impacted area were sampled for an area surrounding the mineral processing plant. After collecting 65 samples and analyzing them for initial Cu, Pb, Zn, and Cd metal contents, the area was zonated based on the concentration distribution using
Determination of the bioaccessible fraction of metals in urban aerosol using simulated lung fluids
Czech Academy of Sciences Publication Activity Database
Coufalík, Pavel; Mikuška, Pavel; Matoušek, Tomáš; Večeřa, Zbyněk
2016-01-01
Roč. 140, SEP (2016), s. 469-475 ISSN 1352-2310 R&D Projects: GA ČR(CZ) GA14-25558S; GA ČR(CZ) GA13-01438S Institutional support: RVO:68081715 Keywords : metal * aerosol * simulated lung fluid Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.629, year: 2016
A Teaching Exercise to Introduce Stable Isotope Fractionation of Metals into Geochemistry Courses
Weiss, Dominik J.; Harris, Caroline; Maher, Kate; Bullen, Thomas
2013-01-01
Variations in the isotopic composition of elements have been widely used to study earth's climate, biosphere, and interior, and more recently to track the fate of contaminants. Within the broad range of elements that exhibit measureable isotopic variations, metal stable isotopes are increasingly applied across the biological, geological,…
Investigation of ionized metal flux fraction in HiPIMS discharges with Ti and Ni targets
Czech Academy of Sciences Publication Activity Database
Kubart, T.; Čada, Martin; Lundin, D.; Hubička, Zdeněk
2014-01-01
Roč. 238, JAN (2014), s. 152-157 ISSN 0257-8972 R&D Projects: GA MŠk LD12002; GA ČR GAP108/12/2104; GA MŠk LH12043 Grant - others:AV ČR(CZ) M100101215 Institutional support: RVO:68378271 Keywords : HiPIMS * reactive sputtering * ionized flux fraction Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.998, year: 2014
Metal uptake by corn grown on media treated with particle-size fractionated biosolids
Energy Technology Data Exchange (ETDEWEB)
Chen, Weiping [Department of Environmental Sciences, University of California, Riverside, CA 92521 (United States)], E-mail: chenweip@yahoo.com.cn; Chang, Andrew C.; Wu, Laosheng [Department of Environmental Sciences, University of California, Riverside, CA 92521 (United States); Zhang, Yongsong [School of Environmental and Natural Resources Sciences, Zhejiang University, Hangzhou, Zhejiang, 31009 (China)
2008-03-15
Particle-size of biosolids may affect plant uptake of heavy metals when the biosolids are land applied. In this study, corn (Zea mays L.) was grown on sand media treated with biosolids to study how particle-size of biosolids affected the plant uptake of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Two biosolids, the Nu-Earth biosolids and the Los Angeles biosolids, of dissimilar surface morphology were utilized. The former exhibited a porous and spongy structure and had considerably greater specific surface area than that of the latter, which was granular and blocky. The specific surface area of the Los Angeles biosolids was inversely proportional to its particle-size, while that of Nu-Earth biosolids did not change significantly with particle-size. For each biosolid, the metal concentrations were not affected by particle sizes. The biomass yields of plants grown on the treated media increased as the biosolid particle-size decreased, indicating that plant uptake of nutrients from biosolids was dependent on interactions at the root-biosolids interface. The effect of particle-size on a metal's availability to plants was element-specific. The uptake rate of Cd, Zn, Cu, and Ni was correlated with the surface area of the particles, i.e., smaller particles having higher specific area provided greater root-biosolids contact and resulted in enhanced uptake of Cd and Zn and slightly less increased uptake of Cu and Ni. The particle morphology of biosolids had limited influence on the plant tissue concentrations of Cr and Pb. For both types of biosolids, total metal uptake increased as biosolid particle-size decreased. Our research indicates that biosolid particle-size distribution plays a deciding role in plant uptake of heavy metals when they are land applied.
Damrongsiri, Seelawut
2018-02-14
The change in environmental conditions during the transportation of contaminated soil and sediment was expected to affect the transformation of heavy metal fractionation. This study disclosed the serious contamination of copper (Cu), lead (Pb), and zinc (Zn) in the sewer sediment of an e-waste dismantling community in Thailand which may be caused by flushed contaminated soil and e-waste fragments. Two environmental conditions were simulated to observe the transformation of heavy metal fractionation. The anoxic sewer condition was induced using high substrate and sulfate in a closed container. The aeration of anoxic contaminated sediment was applied to simulate the transformation to an oxidative environment. The BCR sequential extraction was applied for heavy metal fractionation in this study. The study results exhibited that when heavy metal contaminated soil was transferred into this induced anoxic condition, fractionation was redistributed based on the chemical change of system that tends to be associated into F3 (oxidizable fraction) > F2 (reducible fraction) > F1 (acid soluble/exchangeable fraction). Cu exhibited the outstanding capability association to F3. The iron sulfide was not observed as usual due to its lower capability than Cu, Pb, and Zn. When contaminated sediment was transported to a more oxidative environment, the heavy metals fractionation would be redistributed again among those new environment media. It is noteworthy that F3 of Cu was stable even in oxic conditions. F2 of Fe was not developed by this oxic condition, possibly because its dehydration process was limited. The redistribution under an oxic environment became F1 > F2 > F3 indicating their more available form. This transformation was imperative and should be taken into account in heavy metal contaminated site management and control.
Wang, Fen; Yu, Junxia; Xiong, Wanli; Xu, Yuanlai; Chi, Ru-An
2018-01-01
For selective leaching and highly effective recovery of heavy metals from a metallurgical sludge, a two-step leaching method was designed based on the distribution analysis of the chemical fractions of the loaded heavy metal. Hydrochloric acid (HCl) was used as a leaching agent in the first step to leach the relatively labile heavy metals and then ethylenediamine tetraacetic acid (EDTA) was applied to leach the residual metals according to their different fractional distribution. Using the two-step leaching method, 82.89% of Cd, 55.73% of Zn, 10.85% of Cu, and 0.25% of Pb were leached in the first step by 0.7 M HCl at a contact time of 240 min, and the leaching efficiencies for Cd, Zn, Cu, and Pb were elevated up to 99.76, 91.41, 71.85, and 94.06%, by subsequent treatment with 0.2 M EDTA at 480 min, respectively. Furthermore, HCl leaching induced fractional redistribution, which might increase the mobility of the remaining metals and then facilitate the following metal removal by EDTA. The facilitation was further confirmed by the comparison to the one-step leaching method with single HCl or single EDTA, respectively. These results suggested that the designed two-step leaching method by HCl and EDTA could be used for selective leaching and effective recovery of heavy metals from the metallurgical sludge or heavy metal-contaminated solid media.
Energy Technology Data Exchange (ETDEWEB)
Rana, S; Park, S [McLaren Proton Therapy Center, Karmanos Cancer Institute at McLaren-Flint, Flint, MI (United States); Zheng, Y [Procure Proton Therapy Center, Oklahoma City, OK (United States); Zhang, Y [University of Cincinnati Medical Center, Liberty Township, OH (United States); Pokharel [21st Century Oncology, Estero, FL (United States); Cheng, C [Vantage Oncology, West Hills, CA (United States)
2016-06-15
Purpose: The purpose of this study is to investigate the dosimetric feasibility of hypo-fractionated intensity modulated proton therapy (IMPT) for unilateral metallic prosthesis prostate cancer patients based on proton collaborative group (PCG)-GU002-10 (NCT01230866) protocol criteria. Methods: A total of five unilateral metallic prosthesis prostate cancer cases were included in this retrospective study. For each case, IMPT plans were generated for treatment to be delivered with 7.6 Gy[RBE] per fraction in 5 fractions per week for a total dose of 38 Gy(RBE). Each plan was generated using two anterior-oblique beams and one lateral beam. Treatment plans were optimized with an objective meeting PCG-GU002-10 (NCT01230866) protocol criteria: (i) planning target volume (PTV): D99.5% > 36.1 Gy[RBE], (ii) rectum: V24 < 35%, V33.6 < 10%, (iii) bladder: V39 < 8 cc, and (iv) femoral head: V23 < 1cc. Results: All five cases satisfied PTV D99.5% (average=36.82 Gy[RBE]; range, 36.36–37.13 Gy[RBE]). PTV D95% ranged from 36.66 Gy[RBE] to 38.65 Gy[RBE] and PTV V100 ranged from 95.47% to 97.95%. For the rectum, V24 was less than 35% (average=14.07 Gy[RBE]; range, 6.22–18.42%, whereas V33.6 Gy[RBE] was less than 10% (average=6.83; range, 3.06 – 9.15%). Rectal mean dose ranged from 4.22 Gy[RBE] to 9.97 Gy[RBE]. For the bladder, V39 was found to be less than 8 cc (average=3.69 cc; range, 0.19–7.68 cc). Bladder mean dose ranged from 4.22 Gy[RBE] to 18.83 Gy[RBE]. For the femoral head, V23 was 0 in all five cases. Conclusion: All five unilateral metallic prosthesis prostate cancer IMPT plans generated with one lateral and two anterior-oblique beams satisfied the dosimetric criteria of PCG-GU002-10 (NCT01230866) protocol.
International Nuclear Information System (INIS)
Zhang, Haibo; Luo, Yongming; Makino, Tomoyuki; Wu, Longhua; Nanzyo, Masami
2013-01-01
Highlights: ► A continuous flow ultra-centrifugation method has been developed to obtain fine particles from polluted agricultural soil. ► Pollution source affected the heavy metal fractionation in size-fractions by changing soil particle properties. ► The iron oxides affected the distribution of lead species more than other metals in the smelter dust polluted particles. -- Abstract: The partitioning of pollutant in the size-fractions of fine particles is particularly important to its migration and bioavailability in soil environment. However, the impact of pollution sources on the partitioning was seldom addressed in the previous studies. In this study, the method of continuous flow ultra-centrifugation was developed to separate three size fractions (<1 μm, <0.6 μm and <0.2 μm) of the submicron particles from the soil polluted by wastewater and smelter dust respectively. The mineralogy and physicochemical properties of each size-fraction were characterized by X-ray diffraction, transmission electron microscope etc. Total content of the polluted metals and their chemical speciation were measured. A higher enrichment factor of the metals in the fractions of <1 μm or less were observed in the soil contaminated by wastewater than by smelter dust. The organic substance in the wastewater and calcite from lime application were assumed to play an important role in the metal accumulation in the fine particles of the wastewater polluted soil. While the metal accumulation in the fine particles of the smelter dust polluted soil is mainly associated with Mn oxides. Cadmium speciation in both soils is dominated by dilute acid soluble form and lead speciation in the smelter dust polluted soil is dominated by reducible form in all particles. This implied that the polluted soils might be a high risk to human health and ecosystem due to the high bioaccessblity of the metals as well as the mobility of the fine particles in soil
International Nuclear Information System (INIS)
Wang Chongjong; Wan Leung, Stephen; Chen Huichun; Sun Limin; Fang Fumin; Changchien Chanchao; Huang Engyen; Wu Jiaming; Chen Chuhnchih
1997-01-01
Purpose: To report the treatment results and rectal/bladder complications of cervical carcinoma radically treated with high-dose-rate intracavitary brachytherapy (HDR-IC). The current policy of using three-fraction scheme was examined. Methods and Materials: Between November 1987 and August 1990, 173 patients with cervical carcinoma were treated with curative-intent radiation therapy. Whole pelvic irradiation was administered with 10-MV X ray. Dose to the central cervix was 40-44 Gy in 20-22 fractions, following by pelvic wall boost 6-14 Gy in three to seven fractions with central shielding. 60 Co sources were used for HDR-IC, and 7.2 Gy was given to Point A for three applications, 1-2 weeks apart. Duration of follow-up was 5-7.8 years. Results: Twenty-eight patients (16%) developed central-regional recurrences. Overall 5-year actuarial pelvic control rate was 83%. By stage, 5-year actuarial pelvic control rates were 94%, 87%, and 72% for Stages IB + IIA, IIB + IIIA, and IIIB + IVA, respectively. Thirty-one patients (18%) developed distant metastasis. Overall 5-year actuarial survival rate was 58%. By stage, 5-year actuarial survival rates were 79%, 59%, and 41% for Stages IB + IIA, IIB + IIIA, and IIIB + IVA, respectively. Sixty-six (38%) and 19 patients (11%) developed rectal and bladder complications, respectively. For rectal complication, the overall actuarial rate was 38% at 5 years. By grade, 5-year actuarial rectal complication rates were 24%, 15%, 4%, and 3% for Grades 1-4, respectively. Overall prevalence of rectal complications was 37% and 14% at 2 and 5 years, respectively. Prevalence of low-grade rectal complication (Grades 1 and 2) was dominant at 2 years (30%), but declined to 8% at 5 years. Prevalence of high-grade, severe rectal complication (Grades 3 and 4) remained steady at 2 and 5 years (7% and 6%, respectively). Five-year actuarial bladder complication was 9%. Five-year prevalence of bladder complication was 2%. Conclusion: Using a three-fraction
Hanley, Kevin W; Andrews, Ronnee; Bertke, Steven; Ashley, Kevin
2017-01-01
The National Institute for Occupational Safety and Health (NIOSH) has conducted an occupational exposure assessment study of manganese (Mn) in welding fume at three factories where heavy equipment was manufactured. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. One hundred nine worker-days were monitored for either total or respirable Mn during gas metal arc welding. The samples were analyzed using an experimental method to separate different Mn fractions based on selective chemical solubility. The full-shift total particle size Mn time-weighted average (TWA) breathing zone concentrations ranged 0.38-26 for soluble Mn in a mild ammonium acetate solution; 3.2-170 for Mn0,2+ in acetic acid; 3.1-290 for Mn3+,4+ in hydroxylamine-hydrochloride; and non-detectable (ND)-130 µg m-3 for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all the total particulate Mn TWA fractions yielded results that ranged from 6.9 to 610 µg m-3. The range of respirable size Mn TWA concentrations were 0.33-21 for soluble Mn; 15-140 for Mn0,2+; 14-170 for Mn3+,4+; 5.3-230 for insoluble Mn; and 36-530 µg m-3 for Mn (sum of fractions). Total particulate TWA GM concentrations of the Mn (sum) were 53 (GSD = 2.5), 150 (GSD = 1.7), and 120 (GSD = 1.8) µg m-3 for the three separate factories. Although all of the workers' exposures were measured below the OSHA regulatory permissible exposure limit and NIOSH recommended exposure limit for Mn, 70 welders' exposures exceeded the ACGIH Threshold Limit Values® for total Mn (100 µg m-3) and 29 exceeded the recently adopted respirable Mn TLV (20 µg m-3). This study shows that a welding fume exposure control and management program is warranted for Mn, which includes improved exhaust ventilation and may necessitate the use of respiratory protection, especially for welding parts that impede air circulation. Published by Oxford University Press on behalf of
Wei, Yunmei; Mei, Xiaoxia; Shi, Dezhi; Liu, Guotao; Li, Li; Shimaoka, Takayuki
2017-06-01
Magnetic fractions were extracted from pulverized waste-to-energy (WTE) bottom ashes using a combined wet-dry extraction method. The resulting magnetic and non-magnetic fractions were subjected to compositional, mineralogical, and redox state analyses by X-ray diffraction (XRD), X-ray fluorescence, and X-ray photoelectron spectroscopy (XPS), respectively. The distribution and leaching toxicity of heavy metals were assessed to evaluate potential effects on the environment. Compositional analyses revealed that Fe accounted for 35% of the magnetic fraction of pulverized ashes, which was approximately seven times that of the raw ash. In addition to Fe, elemental Ni, Mn, and Cr were also significantly enriched in the magnetic fractions. The mineralogical analysis determined that Fe was primarily present as hematite and magnetite, and metallic iron was also identified in the magnetic fraction samples. The XPS analysis further proved the existence of zero-valence Fe. However, a significant amount of Fe remained in the non-magnetic fractions, which could partially be ascribed to the intergrowth structure of the various minerals. The elevated concentrations of toxicity characteristic leaching procedure (TCLP)-extracted Mn, Ni, Cr, Cu, Pb, and Zn were primarily ascribed to the lower buffering capability of the magnetic fractions, with the enrichment of Mn, Ni, and Cr in the magnetic fractions also contributing to this elevation.
DEFF Research Database (Denmark)
Ouattara, Lassana; Knutzen, Michael; Keller, Stephan Urs
2010-01-01
We present a new method to define metal electrodes on top of high-aspect-ratio microstructures using standard photolithography equipment and a single chromium mask. A lift-off resist (LOR) layer is implemented in an SU-8 photolithography process to selectively remove metal at the end of the proce......We present a new method to define metal electrodes on top of high-aspect-ratio microstructures using standard photolithography equipment and a single chromium mask. A lift-off resist (LOR) layer is implemented in an SU-8 photolithography process to selectively remove metal at the end...
Stein, Derek R; Hu, Xiaojie; McCorrister, Stuart J; Westmacott, Garrett R; Plummer, Francis A; Ball, Terry B; Carpenter, Michael S
2013-10-01
MS/MS is the technology of choice for analyzing complex protein mixtures. However, due to the intrinsic complexity and dynamic range present in higher eukaryotic proteomes, prefractionation is an important step to maximize the number of proteins identified. Off-gel IEF (OG-IEF) and high pH RP (Hp-RP) column chromatography have both been successfully utilized as a first-dimension peptide separation technique in shotgun proteomic experiments. Here, a direct comparison of the two methodologies was performed on ex vivo peripheral blood mononuclear cell lysate. In 12-fraction replicate analysis, Hp-RP resulted in more peptides and proteins identified than OG-IEF fractionation. Distributions of peptide pIs and hydropathy did not reveal any appreciable bias in either technique. Resolution, defined here as the ability to limit a specific peptide to one particular fraction, was significantly better for Hp-RP. This leads to a more uniform distribution of total and unique peptides for Hp-RP across all fractions collected. These results suggest that fractionation by Hp-RP over OG-IEF is the better choice for typical complex proteome analysis. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Directory of Open Access Journals (Sweden)
Kai Yang
2018-03-01
Full Text Available A composted sewage sludge (CSS was added to the soil of an urban garden at 5%, 10%, and 25% (w/w soil and stabilised for 180 days. Samples were then collected and analysed for total heavy metal concentrations, chemical fractions, and bioaccessibility, together with some physicochemical properties. The results showed that the total chromium (Cr, copper (Cu, lead (Pb, and zinc (Zn concentrations were increased with CSS addition rate. The CSS addition decreased the residual fractions of these four elements. The exchangeable Cr, Cu, and Pb fractions were very small or not detected, while Zn exhibited an increasing trend in its exchangeable fraction with CSS addition rate. The bioaccessibility of these four elements was increased with the CSS addition rate. Moreover, the Cr, Cu, and Zn bioaccessibility correlated positively with the total concentration, while the bioaccessibility of these four elements exhibited a negative correlation with the residual fraction. The fractionation and bioaccessibility of heavy metals may have also been influenced by pH, cation exchange capacity, and organic matter. The risk assessment code reflected the amended soil showed no or low environmental risks for Cr, Cu, and Pb and a medium risk for Zn. The hazardous index values and cancer risk levels indicated that the heavy metals in the soil amended with 25% CSS posed negligible potential noncarcinogenic and carcinogenic risks to children and adults via incidental ingestion.
Zhang, Haibo; Luo, Yongming; Makino, Tomoyuki; Wu, Longhua; Nanzyo, Masami
2013-03-15
The partitioning of pollutant in the size-fractions of fine particles is particularly important to its migration and bioavailability in soil environment. However, the impact of pollution sources on the partitioning was seldom addressed in the previous studies. In this study, the method of continuous flow ultra-centrifugation was developed to separate three size fractions (dust respectively. The mineralogy and physicochemical properties of each size-fraction were characterized by X-ray diffraction, transmission electron microscope etc. Total content of the polluted metals and their chemical speciation were measured. A higher enrichment factor of the metals in the fractions of dust. The organic substance in the wastewater and calcite from lime application were assumed to play an important role in the metal accumulation in the fine particles of the wastewater polluted soil. While the metal accumulation in the fine particles of the smelter dust polluted soil is mainly associated with Mn oxides. Cadmium speciation in both soils is dominated by dilute acid soluble form and lead speciation in the smelter dust polluted soil is dominated by reducible form in all particles. This implied that the polluted soils might be a high risk to human health and ecosystem due to the high bioaccessibility of the metals as well as the mobility of the fine particles in soil. Copyright © 2013 Elsevier B.V. All rights reserved.
Dentoni Litta, Eugenio; Ritzenthaler, Romain; Schram, Tom; Spessot, Alessio; O’Sullivan, Barry; Machkaoutsan, Vladimir; Fazan, Pierre; Ji, Yunhyuck; Mannaert, Geert; Lorant, Christophe; Sebaai, Farid; Thiam, Arame; Ercken, Monique; Demuynck, Steven; Horiguchi, Naoto
2018-04-01
Integration of high-k/metal gate stacks in peripheral transistors is a major candidate to ensure continued scaling of dynamic random access memory (DRAM) technology. In this paper, the CMOS integration of diffusion and gate replacement (D&GR) high-k/metal gate stacks is investigated, evaluating four different approaches for the critical patterning step of removing the N-type field effect transistor (NFET) effective work function (eWF) shifter stack from the P-type field effect transistor (PFET) area. The effect of plasma exposure during the patterning step is investigated in detail and found to have a strong impact on threshold voltage tunability. A CMOS integration scheme based on an experimental wet-compatible photoresist is developed and the fulfillment of the main device metrics [equivalent oxide thickness (EOT), eWF, gate leakage current density, on/off currents, short channel control] is demonstrated.
Energy Technology Data Exchange (ETDEWEB)
Kalman, J., E-mail: judit.kalman@uca.es [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Bonnail-Miguel, E. [Department of Physical-Chemistry, University of Cadiz, Poligono Industrial Rio San Pedro s/n, 11,510 Puerto Real, Cadiz (Spain); Smith, B.D. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Bury, N.R. [Division of Diabetes and Nutritional Science, King' s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom); Rainbow, P.S. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom)
2015-02-15
The relationship between the subcellular distribution of accumulated toxic metals into five operational fractions (subsequently combined into presumed detoxified and non-detoxified components) and toxicity in the clam Scrobicularia plana was investigated under different laboratory exposures. Clams were exposed to metal contaminated media (water and diet) and analysed for the partitioning of accumulated As, Cu and Zn into subcellular fractions. In general, metallothionein-like proteins, metal-rich granules and cellular debris in different proportions acted as main storage sites of accumulated metals in the clam soft tissues for these three metals. No significant differences were noted in the accumulation rates of As, Cu and Zn of groups of individuals with or without apparent signs of toxicity after up to 30 days of exposure to naturally contaminated sediment mixtures. There was, however, an increased proportional accumulation of Cu in the non-detoxified fraction with increased Cu accumulation rate in the clams, suggesting that the Cu uptake rate from contaminated sediments exceeded the combined rates of elimination and detoxification of Cu, with the subsequent likelihood for toxic effects in the clams. - Highlights: • Scrobicularia plana accumulated As, Cu and Zn from naturally toxic sediments. • Toxic metals were accumulated in detoxified and non-detoxified components. • Cu accumulation in the non-detoxified pool increased with increased Cu uptake rate. • Cu uptake rate exceeded combined loss and detoxification rates to cause toxicity.
Directory of Open Access Journals (Sweden)
ESTEFAN M. DA FONSECA
2013-01-01
Full Text Available One of the main results of the processes related to urbanization is the contamination of the adjacent water bodies. Inserted in this context, the Rodrigo de Freitas lagoon is situated in the south zone of the city of Rio de Janeiro. This ecosystem receives several inputs containing all sorts of pollutants, including heavy metals. The present work aimed to study the partitioning of heavy metals in the sediments of Rodrigo de Freitas and the influence of organic matter in this fractionation dynamic. The results of these analyses presented the contents of organic matter as an important metal-capturing agent. Fractionation of organic matter resulted in a predominance of humine. Heavy metal partitioning showed that the metals bound by the water-soluble phase have no significant concentrations. Special features such as, reducing sediment, high levels of organic matter and fine grain size have transformed this ecosystem in an effective deposit of pollutants, where heavy metals are not available in easily reactive fractions.
Drosos, Marios; Leenheer, Jerry A.; Avgeropoulos, Apostolos; Deligiannakis, Yiannis
2014-01-01
A fractionation technique, combining dialysis removal of metal and ash components with hydrofluoric acid and pH 10 citrate buffer followed by chromatography of dialysis permeate on XAD-8 resin at decreasing pH values, has been applied to lignite humic acid (lignite-HA) and soil humic acid (soil-HA). H-binding data and non ideal competitive adsorption-Donnan model parameters were obtained for the HA fractions by theoretical analysis of H-binding data which reveal a significant increase of the carboxyl and the phenolic charge for the lignite-HA fractions vs. the parental lignite humic acid (LParentalHA). The fractionated lignite-HA material consisted mainly of permeate fractions, some of which were fulvic acid-like. The fractionated soil-HA material consisted mainly of large macromolecular structures that did not permeate the dialysis membrane during deashing. Chargeable groups had comparable concentrations in soil-HA fractions and parental soil humic acid (SParentalHA), indicating minimal interference of ash components with carboxyl and phenolic (and/or enolic) groups. Fractionation of HA, combined with theoretical analysis of H-binding, can distinguish the supramolecular vs. macromolecular nature of fractions within the same parental HA.
Energy Technology Data Exchange (ETDEWEB)
Gao, Peng [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003 (United States); Liu, Sa [Environmental Health Sciences Division, School of Public Health, University of California, Berkeley, CA, 94720-7360 (United States); Ye, Wenyuan [Department of Chemical Engineering, KU Leuven, Willem de Croylaan 46, B-3001 Heverlee (Belgium); Lin, Nan; Meng, Ping [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Feng, Yujie, E-mail: yujief@hit.edu.cn [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Zhang, Zhaohan; Cui, Fuyi; Lu, Binyu [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No. 73 Huanghe Road, Nangang District, Harbin 150090 (China); Xing, Baoshan [Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003 (United States)
2015-03-01
Limited information is available on the bioaccessible fraction of trace metals in the resuspended fraction of settled bus dust in order to estimate bus drivers ' occupational exposure. In this study, 45 resuspended fraction of settled dust samples were collected from gasoline and compressed natural gas (CNG) powered buses and analyzed for trace metals and their fraction concentrations using a three-step sequential extraction procedure. Experimental results showed that zinc (Zn) had the greatest bioaccessible fraction, recorded as an average of 608.53 mg/kg, followed in order of decreasing concentration by 129.80 mg/kg lead (Pb), 56.77 mg/kg copper (Cu), 34.03 mg/kg chromium (Cr), 22.05 mg/kg nickel (Ni), 13.17 mg/kg arsenic (As) and 2.77 mg/kg cadmium (Cd). Among the three settled bus dust exposure pathways, ingestion was the main route. Total exposure hazard index (HIt) for non-carcinogenic effect trace metals was lower than the safety level of 1. The incremental lifetime cancer risk (ILCR) for drivers was estimated for trace metal exposure. Pb and Ni presented relatively high potential risks in the non-carcinogenic and potentially carcinogenic health assessment for all drivers. ILCR was in the range of 1.84E − 05 to 7.37E − 05 and 1.74E − 05 to 6.95E − 05 for gasoline and CNG buses, respectively. - Highlights: • As, Cd and Ni had relatively higher bioaccessibility and mobility in the resuspended fraction of settled bus dust. • Bioaccessible metal concentrations were higher in gasoline-fueled buses than those in CNG-fueled buses. • The carcinogenic risk probabilities to drivers were around the acceptable level.
International Nuclear Information System (INIS)
Gao, Peng; Liu, Sa; Ye, Wenyuan; Lin, Nan; Meng, Ping; Feng, Yujie; Zhang, Zhaohan; Cui, Fuyi; Lu, Binyu; Xing, Baoshan
2015-01-01
Limited information is available on the bioaccessible fraction of trace metals in the resuspended fraction of settled bus dust in order to estimate bus drivers ' occupational exposure. In this study, 45 resuspended fraction of settled dust samples were collected from gasoline and compressed natural gas (CNG) powered buses and analyzed for trace metals and their fraction concentrations using a three-step sequential extraction procedure. Experimental results showed that zinc (Zn) had the greatest bioaccessible fraction, recorded as an average of 608.53 mg/kg, followed in order of decreasing concentration by 129.80 mg/kg lead (Pb), 56.77 mg/kg copper (Cu), 34.03 mg/kg chromium (Cr), 22.05 mg/kg nickel (Ni), 13.17 mg/kg arsenic (As) and 2.77 mg/kg cadmium (Cd). Among the three settled bus dust exposure pathways, ingestion was the main route. Total exposure hazard index (HIt) for non-carcinogenic effect trace metals was lower than the safety level of 1. The incremental lifetime cancer risk (ILCR) for drivers was estimated for trace metal exposure. Pb and Ni presented relatively high potential risks in the non-carcinogenic and potentially carcinogenic health assessment for all drivers. ILCR was in the range of 1.84E − 05 to 7.37E − 05 and 1.74E − 05 to 6.95E − 05 for gasoline and CNG buses, respectively. - Highlights: • As, Cd and Ni had relatively higher bioaccessibility and mobility in the resuspended fraction of settled bus dust. • Bioaccessible metal concentrations were higher in gasoline-fueled buses than those in CNG-fueled buses. • The carcinogenic risk probabilities to drivers were around the acceptable level
DEFF Research Database (Denmark)
Hansen, Elo Harald; Miró, Manuel; Long, Xiangbao
2006-01-01
. In this context sequential injection (SI) and lab-on-valve (LOV) schemes have proven themselves as superb vehicles to act as front-end microanalytical methodologies, particularly when employing solid-phase extraction (SPE) procedures. In this communication, selected SPE-procedures in a bead-renewable fashion...... are presented as based on the exploitation of micro-sequential injection (μSI-LOV) using hydrophobic as well as hydrophilic bead materials. The examples given comprise the presentation of a universal approach for SPE-assays, front-end speciation of Cr(III) and Cr(VI) in a fully automated and enclosed set...
Directory of Open Access Journals (Sweden)
Mukhtar A.
2013-04-01
Full Text Available In present study, an in-vitro physiologically based extraction test has been applied for extraction of bio-accessible trace metal fractions in airborne particulate matter (APM samples collected from different urban sites in Austria and Pakistan using the leaching agents H2O, sodium chloride, ammonium acetate, ammonium citrate, synthetic gastric juice and artificial lung fluids. Obtained extracts were then measured using an ETV-ICP-OES procedure which allowed highly sensitive measurement of dissolved analytes even in the presence of leaching agents. Derived results indicated that the investigated leaching agents extract different amounts of trace metals. In general, leaching agents with organic nature yielded comparatively greater extractable and thus bio-accessible trace metal fractions to that of simple solvents like H2O or aqueous NaCl solution. With water, only 26.3±4.0% of Cd was found to be bio-accessible whereas 88.4±24.8 of Cd was obtained as bio-accessible fraction with the use of synthetic gastric juice. The concentrations of bio-accessible metal fractions varied from 0.4 ng m−3 (Cd to 714 ng m−3 (Zn and 0.3 ng m−3 (Cd to 190 ng m−3 (Zn for PM10 samples collected from Karachi (Pakistan and Graz (Austria respectively.
Hui Pan; Chung-Yun Hse; Robert Gambrell; Todd F. Shupe
2009-01-01
Chromated copper arsenate (CCA)-treated wood was liquefied with polyethylene glycol/glycerin and sulfuric acid. After liquefaction, most CCA metals (98% As, 92% Cr, and 83% Cu) were removed from liquefied CCA-treated wood by precipitation with calcium hydroxide. The original CCA-treated wood and liquefied CCA-treated wood sludge were fractionated by a modified...
Wong, Tony E.; Nusbaumer, Jesse; Noone, David C.
2017-06-01
All physical process models and field observations are inherently imperfect, so there is a need to both (1) obtain measurements capable of constraining quantities of interest and (2) develop frameworks for assessment in which the desired processes and their uncertainties may be characterized. Incorporation of stable water isotopes into land surface schemes offers a complimentary approach to constrain hydrological processes such as evapotranspiration, and yields acute insight into the hydrological and biogeochemical behaviors of the domain. Here a stable water isotopic scheme in the National Center for Atmospheric Research's version 4 of the Community Land Model (CLM4) is presented. An overview of the isotopic methods is given. Isotopic model results are compared to available data sets on site-level and global scales for validation. Comparisons of site-level soil moisture and isotope ratios reveal that surface water does not percolate as deeply into the soil as observed in field measurements. The broad success of the new model provides confidence in its use for a range of climate and hydrological studies, while the sensitivity of simulation results to kinetic processes stands as a reminder that new theoretical development and refinement of kinetic effect parameterizations is needed to achieve further improvements.
Samonova, Olga; Aseyeva, Elena
2017-04-01
A detailed study of heavy metals distribution in various soil grain-size fractions helps to increase the knowledge about the complex nature of metals' occurrence and their distribution pathways in the environment. On the basis of particle size fractionation of topsoil horizons we examined the specific behavior of heavy metals in a small erosional landform located in the humid temperate zone of the Russian Plain. The object of the study is a 400 m small U-shaped dry valley (balka in Russian) with a catchment area of 32.8 ha located in the central part of the Protva river basin, 100 km southwest of Moscow. The uppermost parts of the landform are incised in Late Pleistocene loessial loams, which cover significant portions of interfluve area in the region, while the middle and the lower parts cut through Middle Pleistocene glacial sediments. A total of 50 samples were collected from topsoil horizons of different landform geomorphic units along three cross-sections as well as along the bottom of the landform and its detrital fan. Samples were analyzed for Mn, Cu, Ni, Co, Cr, Zn, Pb, Ti, Zr, and Fe content. Eleven samples were chosen for physical fractionation into 5 grain-size fractions (1-0.25 mm, 0.25-0.05 mm, 0.05-0.01 mm, 0.01-0.001 mm and calculated for Cu, Ni, Co, Fe, Mn, Ti and Zr reach their maximum in the 1-0.25 mm fraction (for Cu and Ni exceeding 75%, for Ti, Zr being around 40%). For Zn, Cr and Pb the maximum variation (50-60%) was found in the 0.25-0.05 mm fraction. In contrast, the two studied silt fractions and also the clay showed very low variations of all metal contents (except for Mn) characteristically in the range between 6% (Cr) and 23.5% (Zn). Unlike the finer fractions, which displayed very poor geochemical differentiation across the landform's geomorphic units, the coarser (sand) fractions showed distinct spatial patterns in the elements' distribution, possibly related to migration processes, the depletion of metals in the landforms' slopes and
Barrera-Ballesteros, J. K.; Heckman, T.; Sánchez, S. F.; Zakamska, N. L.; Cleary, J.; Zhu, G.; Brinkmann, J.; Drory, N.; THE MaNGA TEAM
2018-01-01
We determine the local metallicity of the ionized gas for more than 9.2 × 105 star-forming regions (spaxels) located in 1023 nearby galaxies included in the Sloan Digital Sky Survey-IV MaNGA integral field spectroscopy unit survey. We use the dust extinction derived from the Balmer decrement and the stellar template fitting in each spaxel to estimate the local gas and stellar mass densities, respectively. We also use the measured rotation curves to determine the local escape velocity (V esc). We then analyze the relationships between the local metallicity and both the local gas fraction (μ) and V esc. We find that metallicity decreases with both increasing μ and decreasing V esc. By examining the residuals in these relations we show that the gas fraction plays a more primary role in the local chemical enrichment than does V esc. We show that the gas-regulator model of chemical evolution provides a reasonable explanation of the metallicity on local scales. The best-fit parameters for this model are consistent with the metal loss caused by momentum-driven galactic outflows. We also argue that both the gas fraction and the local escape velocity are connected to the local stellar surface density, which in turn is a tracer of the epoch at which the dominant local stellar population formed.
Directory of Open Access Journals (Sweden)
Ali Afshari
2017-01-01
Full Text Available Introduction: Heavy metals are found to be one of the major environmental hazardous contaminants, for human health, animal life, air quality and other components of environment. They can affect geochemical cycles and accumulate in animal tissues since physical processes are not able to remove them, so they are consistent in long term. The analysis of the total concentration of heavy metals in soil may provide information about soils enrichment but in general, it is widely used to determine the potential mobility of heavy metals in environmental behavior under chemical forms of metals in soils. Heavy metals existat several phases including water-soluble, exchangeable, bounded to organic matter, bounded to carbonates, bounded to Fe-Mn oxides, secondary clay minerals and residual fraction within primary minerals network. There is a dynamic equilibrium between different fractions of elements in soil. The main objectives of the present study were a The analysis of the total concentration of heavy metals such as Fe, Mn, Ni, Cr, Co, Pb, Zn, Cd and Cu and b The fractionations of heavy metals and identification of controlling factors to distribution and behavior of heavy metals in soils at different land uses. Materials and Methods: The study was performed at central area of Zanjan province (Iran. The study area was over 2000 km2 in coordinates 20´ 36° to 41´ 36° E and 19´ 48° to 53´ 48° N. The average altitudes were over 1500 meters above sea level. The major land uses of the study area included agriculture (AG, rangeland (RA and urban (UR. Sample collection was done based on the random grid method in August 2011. Surface soil samples (0-10 cm depth were taken from grid centers included 137, 77 and 27 samples from AG, RA and UR land uses, respectively. The samples were digested in Nitric acid 5 normal (Sposito et al., 1982 and total concentration of Pb, Zn, Ni, Mn, Cu, Cr, Fe and Co were measured by Perkin-Elmer: AA 200 atomic absorption
Mao, Lingchen; Ye, Hua; Li, Feipeng; Tao, Hong; Shi, Liu; Chen, Ling; Shi, Weiling; Yan, Geng; Chen, Hao
2017-12-15
Elevation in toxic trace metal concentration found in coastal sediments in recent years (2013-2016) increased the risk to the aquaculture industry in south Hangzhou bay. This study assessed the main factors controlling the metal distribution and mobility in sediments by sampling from 20 sites along the bank. Spatial distribution and cluster analysis indicated that Cd, As, Hg and Sb attributed to anthropogenic terrestrial sources; while Cr, Co, Cu, Ni, Zn, and Pb, carried by fine-grained sediments and accumulated on tidal flat, were inputted from marine sources. High mobility of Cd was expected because of its considerable proportion (~50%) associated with the acid extractable fraction. Pb, Cu and Co in redox sensitive fraction should also be taken into concern in management of reclaimed area affected by tide. Risk assessments by potential ecological risk index (PERI) emphasised the importance of further monitor and proper treatment of 4 terrestrial generated metals in sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.
Fiege, A.; Ruprecht, P.; Simon, A. C.; Holtz, F.
2017-12-01
Mafic magma recharge is a common process that triggers physical and chemical mixing in magmatic systems and drives their evolution, resulting in, e.g., hybridization and volcanic eruptions. Once magma-magma contact is initiated, rapid heat-flux commonly leads to the formation of a cooling-induced crystal mush on the mafic side of the interface. Here, on a local scale (µm to cm), at the magma-magma interface, melt-melt diffusive exchange is required to approach equilibrium. Significant chemical potential gradients drive a complex, multi-element mass flux between the two systems (Liang, 2010). This diffusive-equilibration often controls crystal dissolution rates within the boundary layers and, thus, the formation of interconnected melt or fluid networks. Such networks provide important pathways for the transport of volatiles and trace metals from the mafic recharge magma to the felsic host magma, where the latter may feed volcanic activities and ore deposits. While major element diffusion in silicate melts is mostly well understood, even in complex systems, the available data for many trace element metals are limited (Liang, 2010; Zhang et al., 2010). Differences in diffusivity in a dynamic, mixing environment can cause trace element fractionation, in particular during crystallization and volatile exsolution and separation. This may affect trace element signatures in phenocrysts and magmatic volatile phases that can form near a magma-magma boundary. As a result, the chemistry of volcanic gases and magmatic-hydrothermal ore deposits may be partially controlled by such mixing phenomena. We performed melt-melt diffusion-couple experiments at 150 MPa, 1100°C, FMQ, FMQ+1 and FMQ+3 (FMQ: fayalite-magnetite-quartz oxygen fugacity buffer). Hydrated, sulfur-bearing cylinders of dacite and basaltic andesite were equilibrated for up to 20 h. Major and trace element gradients were measured by using laser-ablation ICP-MS and electron microprobe analyses. The results we will
Mohr, Victoria; Miró, Manuel; Limbeck, Andreas
2017-04-01
For a realistic evaluation of the potential hazard emanating from airborne particulate matter (APM), the determination of the total inhaled metal amounts associated with APM is insufficient in risk assessment. Additional information about metal fractions that can be mobilized by the human body is necessary, because only those soluble (also called bioaccessible) fractions can be absorbed by the human body, and thus potentially cause adverse health effects. In the present study, a dynamic flow-through approach as a front end to inductively coupled plasma optical emission spectrometry (ICP-OES) exploiting advanced flow analysis is employed for on-line handling of multiple APM samples and determination of bioaccessible trace metals under worst case extraction scenarios. The method is based on on-line continuous extraction of filter samples with synthetic gastric fluid followed by on-line ICP-OES measurement of the dissolved fraction of trace metals. The assembly permits an automated successive measurement of three sample replicates in less than 19 min. The on-line extraction procedure offers increased sample throughput and reduced risk of sample contamination and overcomes metal re-adsorption processes compared to the traditional batch-wise counterparts. Furthermore, it provides deeper information on the kinetics of the leaching process. The developed procedure was applied to the determination of bioaccessible metal fractions (Al, Ba, Cu, Fe and Mn as model analytes) in PM10 samples from Palma de Mallorca (Spain) and Vienna (Austria). Graphical Abstract On-line gastric bioaccessibility of elements in airborne particulate matter.
International Nuclear Information System (INIS)
Rivard, C.; Pelletier, M.; Villieras, F.; Michau, N.
2012-01-01
Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste, it is of prime importance to understand the interaction mechanisms between the geological matrix, Callovo-Oxfordian clay rock (COx) and metallic iron, from the package overpack. In order to evidence the individual role of each clay component entering in the mineralogy of the COx, interactions between metallic iron and pure clays (smectites, illite and kaolinite) were first conducted. To investigate the role of the other minerals, the reactivity of COx, COx clay fraction (COxCF) and mixtures between COxCF and quartz, calcite or pyrite, was studied. Clays and additional minerals were put in contact with powder metallic iron with a weight ratio iron:clay fixed at 1:3 and a clay:solution ratio of 1:20. Proportions of non-clay minerals were deduced from the average COx composition: 50% clays, 24.5% quartz, 24.5% calcite and 1% pyrite. Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L -1 , CaCl 2 0.04 M.L -1 ) in Parr reactors for durations of one, three or nine months. After reaction, solid and liquid phases were separated by centrifugation and characterized by classical techniques combining chemical analyses (liquid analyses, transmission electron microscopy combined with Energy Dispersive of X-rays spectroscopy TEM-EDS), mineralogical (X-ray diffraction), spectroscopic ( 57 Fe Moessbauer) and morphometric techniques (TEM, scanning electron microscopy and N 2 adsorption). For COx, COxCF and all the pure clay phases, major evolutions were observed during the first month, which shows that the oxidation of metallic iron is rapid in our experimental conditions. Release of iron cations in solution, pH increase (8-10) and Eh decrease (reductive conditions) are responsible for the partial dissolution of initial clay phases. Released iron is involved in the crystallization of Fe
Othmani, Mohamed Ali; Souissi, Fouad; Durães, Nuno; Abdelkader, Moussi; da Silva, Eduardo Ferreira
2015-08-01
This study aims to evaluate the impact of the former mining Touiref district (NW Tunisia) on the spatial distribution of metal contamination. In order to characterize the metal content of the tailings and to assess how far the soils from the district could be impacted by metals, a sampling campaign was conducted. According to the spatial distribution concentration maps of potential toxic elements (PTE), the highest concentrations occur near the flotation tailings and in mining facilities and decrease abruptly with distance. These results confirm that wind is the main agent capable of dispersing metals in a W-E direction, with concentrations exceeding the standards of soil quality for Cd, Pb and Zn over several hundred metres away from the source, facilitated by the small-size fraction and low cohesion of tailings particles. Chemical fractionation showed that Pb and Cd were mainly associated with the acid-soluble fraction (carbonates) and Fe-(oxy) hydroxides, while Zn was mainly associated with Fe-(oxy) hydroxides but also with sulphides. Thus, the immobilization of metals in solution may be favoured by the alkaline conditions, promoted by carbonates dissolution. However, being carbonate important-bearing phases of Cd and Pb (but also for Zn), the dissolution facility of these minerals may enhance the release of metals, particularly far away from the mine where the physicochemical conditions can be different. Also, the metal uptake by plants in these alkaline conditions may be favoured, especially if secondary phases with high sorption ability are reduced at this site. A remediation plan to this area is needed, with particularly attention in the confinement of the tailings.
Energy Technology Data Exchange (ETDEWEB)
Verma, Vivek [Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska (United States); Shostrom, Valerie K. [Department of Biostatistics, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska (United States); Zhen, Weining; Zhang, Mutian [Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska (United States); Braunstein, Steve E. [Department of Radiation Oncology, University of California, San Francisco, San Francisco, California (United States); Holland, John [Department of Radiation Medicine, Oregon Health & Science University, Portland, Oregon (United States); Hallemeier, Christopher L. [Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota (United States); Harkenrider, Matthew M. [Department of Radiation Oncology, Loyola University Stritch School of Medicine, Maywood, Illinois (United States); Iskhanian, Adrian [Department of Radiation Oncology, University of Miami Sylvester Comprehensive Cancer Center, Miami, Florida (United States); Jabbour, Salma K. [Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, New Jersey (United States); Attia, Albert [Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, Tennessee (United States); Lee, Percy [Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, California (United States); Wang, Kyle [Department of Radiation Oncology, University of North Carolina School of Medicine, Chapel Hill, North Carolina (United States); Decker, Roy H. [Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut (United States); McGarry, Ronald C. [Department of Radiation Oncology, University of Kentucky, Lexington, Kentucky (United States); Simone, Charles B., E-mail: charlessimone@umm.edu [Department of Radiation Oncology, University of Maryland Medical Center, Baltimore, Maryland (United States)
2017-03-15
Purpose: To describe the impact of fractionation scheme and tumor location on toxicities in stereotactic body radiation therapy (SBRT) for ≥5-cm non-small cell lung cancer (NSCLC), as part of a multi-institutional analysis. Methods: Patients with primary ≥5-cm N0 M0 NSCLC who underwent ≤5-fraction SBRT were examined across multiple high-volume SBRT centers. Collected data included clinical/treatment parameters; toxicities were prospectively assessed at each institution according to the Common Terminology Criteria for Adverse Events. Patients treated daily were compared with those treated every other day (QOD)/other nondaily regimens. Stratification between central and peripheral tumors was also performed. Results: Ninety-two patients from 12 institutions were evaluated (2004-2016), with median follow-up of 12 months. In total there were 23 (25%) and 6 (7%) grade ≥2 and grade ≥3 toxicities, respectively. Grades 2 and 3 pulmonary toxicities occurred in 9% and 4%, respectively; 1 patient treated daily experienced grade 5 radiation pneumonitis. Of the entire cohort, 46 patients underwent daily SBRT, and 46 received QOD (n=40)/other nondaily (n=6) regimens. Clinical/treatment parameters were similar between groups; the QOD/other group was more likely to receive 3-/4-fraction schemas. Patients treated QOD/other experienced significantly fewer grade ≥2 toxicities as compared with daily treatment (7% vs 43%, P<.001). Patients treated daily also had higher rates of grade ≥2 pulmonary toxicities (P=.014). Patients with peripheral tumors (n=66) were more likely to receive 3-/4-fraction regimens than those with central tumors (n=26). No significant differences in grade ≥2 toxicities were identified according to tumor location (P>.05). Conclusions: From this multi-institutional study, toxicity of SBRT for ≥5-cm lesions is acceptable, and daily treatment was associated with a higher rate of toxicities.
Energy Technology Data Exchange (ETDEWEB)
Datta, D.K. [Khulna Univ. (Bangladesh). Dept. of Environmental Sciences; Subramanian, V. [Jawaharlal Nehru Univ., New Delhi (India). School of Environmental Sciences
1998-11-01
The lower Ganges-Brahmaputra-Meghna (G-B-M) drainage basin occupies the total Bengal Basin, which is one of the unique basins of the world because of its location and size, density of population, and catastrophic deposition of sediments. The increased heavy metal concentration in the 63 m fraction of surface sediments shows similarity among major segments of the G-B-M system in the basin, which reflects the homogenization of lithologic and chemical diversity of the greater denudation regime by the river processes. The differences in heavy metal concentration in the lower G-B-M system with that of its upper and middle counterpart is mainly related to the contrast between Himalayan rivers and the other major South Asian rivers, and may be due to the geological differences of their denudation regime. Heavy metals in the Lower G-B-M system have an affinity towards the clay fraction of the sediments. The correlation matrix of heavy metals in the lower Brahmaputra and Meghna suggests the importance of Fe-Mn oxyhydroxides in their accumulations. Iron, Ti and Mn are higher in the Meghna main channel, Zn is higher in the Meghna tributaries, and Cr is higher in both the Brahmaputra and Meghna compared to the value for standard shale. The enrichment factor is {<=}1 for most of the metals except Mn which is relatively higher in the Meghna and lower Ganges main channels. The geoaccumulation index (I{sub geo}) for most of the heavy metals lies below grade zero, suggesting unpolluted sediment quality. The lower Ganges system shows relatively higher concentration in the nondetrital fraction of heavy metals, probably due to the presence of petroleum refinery, industrial and mining effluents, and agricultural runoff in the drainage basin. The relative uniformity in concentration of heavy metals in vertical profiles may be due to the uniformity in sediment grain size and catastrophic deposition of sediments, where the time period represented by the vertical sediment column is not
Energy Technology Data Exchange (ETDEWEB)
Al Darouich, T.
2005-07-15
The thermal evolution of reservoir oils is controlled by the kinetics of cracking reactions. The present work is concerned with the study of the thermal stability of the light aromatic components (C{sub 6}-C{sub 14}) of crude oils under geological conditions. The aim is to predict this stability through a mode l derived from laboratory pyrolyses. The light cut < 250 deg. C of Safaniya crude oil, corresponding to the C{sub 15} components, was obtained by fractionated distillation; pure aromatic fraction was then separated by liquid chromatography. Detailed molecular characterisation of the aromatic fraction was acquired using HPLC, GC and GC/MS. Then, quantified individual aromatic compounds were lumped into six molecular classes: BTXN, methyl-aromatics, alkyl-aromatics, naphthenic-aromatics, indene and sulphur - containing aromatics. Pyrolyses of the aromatic fraction were performed in gold tubes at 100 bars and different temperature/time conditions in a wide range (1 to 93%) of global conversion. Pyrolysis effluents were analysed and lumped into classes. The pyrolysis data were used to elaborate a semi - empirical kinetic scheme of 13 stoichiometric reactions for the primary and secondary cracking of the unstable classes. The scheme kinetic parameters were first estimated, and then numerically optimised, with the constraints of mass balance and hydrogen conservation. A set of pyrolysis experiments was performed at 375 deg.C under high pressures: 400, 800 and 1200 bars. Increasing slowing down in conversion rate with increasing pressure was thus observed compared to experiments at 100 bars. A slight selective effect of pressure on the different aromatic classes of the charge and on the product distribution was evidenced. The extrapolation of the kinetic model to the conditions of Elgin Field (North Sea) showed that pressure effect should shift the thermal cracking of light aromatics to higher temperatures by almost 8 deg. C. (author)
Directory of Open Access Journals (Sweden)
Roy Andreas
2016-05-01
Full Text Available Geochemical fractionation of Cadmium (Cd, Lead (Pb, Cobalt (Co, Zink (Zn, Iron (Fe and Manganese (Mn in sediment of the East China Sea were determined using four-stages of modified BCR sequential extraction method combination with ICP-MS. The total concentration of trace metals in sediment samples were in the following order: Fe >Mn>Pb> Zn > Co > Cd. Cd is present mainly in acid soluble fraction. Pb and Mn are in the group with presenting of easy reducible fraction and acid soluble fraction. Fe and Co were found in a group with mainly in residual fraction, while Zn was distributed in all four fractions. The highest contamination factors were found for Cd and Mn while the lowest were found for Fe and Co in almost station. The result showed low risk for Fe and Co in all station, Pb (except S2 and S3, Zn at S3,S6 and S7, and Mn at S1. A medium risk is indicated for Pb at S2 and S3, Zn at S1 and S5, and Mn at S2 and S6. A high risk showed for Zn at S2 and S4, and Mn at S4 and S5, while Cd at almost station (except S4 was very high risk.
Jorge Mendoza, C; Tatiana Garrido, R; Cristian Quilodrán, R; Matías Segovia, C; José Parada, A
2017-06-01
A study is made to evaluate the bioaccessibility of heavy metals in contaminated soils through a simple bioaccessibility extraction test (SBET), applied to the analysis of both the gastric and intestinal phases. Soils with high metal content of the Mapocho, Cachapoal, and Rancagua series were studied; they are located in suburban areas of large cities in the central valley of Chile. The bioaccessible concentrations of Cd, Cr, Cu, Ni, Pb, and Zn were related to the main physicochemical characteristics of the soils and to the chemical forms obtained by sequential extraction. The elements Cd, Cu, Ni, and Zn are distributed in the soils between the exchangeable fractions, bound to oxides, to organic matter, and in the residual fraction. On the other hand, Cr and Pb are found mainly in the fractions bound to organic matter and in the residual fraction. The three soils have a high Cu content, (640-2060 mg/kg), in the order Cachapoal > Rancagua > Mapocho. The SBET test allowed establishing a different bioaccessibility for the elements in the soil. Cu was notoriously bioaccessible in both the gastric and intestinal phases in the three soils, reaching more than 50% in the Cachapoal and Rancagua soils. The other elements, regardless of the soil, were bioaccessible only in one of the phases, more frequently in the gastric phase. The multiple correlation study indicates that the metal forms have a higher incidence than the soil's physicochemical factors on the extractability to evaluate the human oral bioaccessibility of the metals. Copyright © 2017 Elsevier Ltd. All rights reserved.
Chatzistathis, T; Papaioannou, A; Gasparatos, D; Molassiotis, A
2017-12-01
Organic farming has been proposed as an alternative agricultural system to help solve environmental problems, like the sustainable management of soil micronutrients, without inputs of chemical fertilizers. The purposes of this study were: i) to assess Fe, Mn, Zn and Cu bioavailability through the determination of sequentially extracted chemical forms (fractions) and their correlation with foliar micronutrient concentrations in mature organic olive (cv. 'Chondrolia Chalkidikis') groves; ii) to determine the soil depth and the available forms (fractions) by which the 4 metals are taken up by olive trees. DTPA extractable (from the soil layers 0-20, 20-40 and 40-60 cm) and foliar micronutrient concentrations were determined in two organic olive groves. Using the Tessier fractionation, five fractions, for all the metals, were found: exchangeable, bound to carbonates (acid-soluble), bound to Fe-Mn oxides (reducible), organic (oxidizable), as well as residual form. Our results indicated that Fe was taken up by the olive trees as organic complex, mainly from the soil layer 40-60 cm. Manganese was taken up from the exchangeable fraction (0-20 cm); Zinc was taken up as organic complex from the layers 0-20 and 40-60 cm, as well as in the exchangeable form from the upper 20 cm. Copper was taken up from the soil layers 0-20 and 40-60 cm as soluble organic complex, and as exchangeable ion from the upper 20 cm. Our data reveal the crucial role of organic matter to sustain metal (Fe, Zn and Cu) uptake -as soluble complexes-by olive trees, in mature organic groves grown on calcareous soils; it is also expected that these data will constitute a thorough insight and useful tool towards a successful nutrient and organic C management for organic olive groves, since no serious nutritional deficiencies were found. Copyright © 2017 Elsevier Ltd. All rights reserved.
McNellis, Erik; Reuter, Karsten; Scheffler, Matthias
2008-03-01
The adsorption of benzene (C6H6) at the Cu(111) surface is a much studied model system for the interaction of larger π-conjugated molecules with solid surfaces. At first glance a simple system, the suspected predominantly van der Waals type bonding at the extended metal surface poses a severe challenge for accurate first-principles calculations. Density-Functional Theory (DFT) with local and semi-local exchange-correlation (xc) functionals is uncertain to properly account for this type of bonding, while the system sizes required to correctly grasp the metallic band structure are computationally untractable with correlated wave function techniques. We overcome these limitations with a recently introduced ``local xc correction'' scheme [1], correcting the adsorption energetics from present-day DFT xc functionals with hybrid functional and Møller-Plesset perturbation theory calculations for small clusters. From the obtained convergence of the xc correction with cluster size we can disentangle short-range and dispersion type contributions to the bonding of the molecule at different heights above the surface. This enables us to qualify the role played by the two contributions in determining the binding energetics and geometry. [1] Q.-M. Hu, K. Reuter, and M. Scheffler, PRL 98, 176103 (2007) and 99, 169903 (2007); C. Tuma and J. Sauer, CPL 387, 388 (2004).
Huang, Chun-Li; Bao, Lian-Jun; Luo, Pei; Wang, Zhao-Yi; Li, Shao-Meng; Zeng, Eddy Y
2016-11-05
Health risk of residents dwelling around e-waste recycling zones has been a global concern, but has not been adequately examined. The present study was intended to evaluate the potential health risk of residents through inhalation exposure to size-fractionated particle-bound heavy metals in a typical e-waste recycling zone, South China. Anthropogenic metals (Zn, Se, Pb, Sb, As, and Cd) were predominantly enriched in fine particles (Dp1.8μm). Although the daily inhalation intakes of the target metals were significantly lower than those through food consumption and ingestion of house dust, the hazard quotients of total metals for adults (95% CI: 1.0-5.5) and children (95% CI: 3.0-17) were greater than 1. Moreover, the incremental lifetime cancer risks of five carcinogenic metals (Cr, Co, Ni, As, and Cd) for adults and children were 1.3×10(-3) (95% CI: 4.1×10(-4)-3.0×10(-3)) and 3.9×10(-3) (95% CI: 1.3×10(-3)-8.6×10(-3)), respectively, substantially higher than the acceptable cancer risk range of 10(-6)-10(-4). All these findings suggested that health risks were high for local residents dwelling around the e-waste recycling zone through inhalation exposure to particle-bound heavy metals, for both adults and children. Copyright © 2016 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Morgan, T.J.
1979-01-01
The purpose of this program is to measure cross sections and equilibrium fractions of deuterium ions and atoms in metal vapors. In particular, in connection with double charge exchange D - ion sources, there is concern with D - formation in alkaline-earth vapor targets. Also, in connection with possible metal vapor contamination in the system, there is concern with cross sections for high energy D + , D 0 and D - collisions with these metal vapors. Results from this research will fill in a gap in knowledge of single and double charge transfer and multiple collision processes in alkaline-earth targets and provide a better understanding of D - formation mechanisms. A list of publications is included. 6 references
Ayaz, Muhammad; Junaid, Muhammad; Subhan, Fazal; Ullah, Farhat; Sadiq, Abdul; Ahmad, Sajjad; Imran, Muhammad; Kamal, Zul; Hussain, Sajid; Shah, Syed Majid
2014-12-03
Polygonum hydropiper L decoctions are traditionally used in the treatment of various ailments including inflammation, dyspepsia, diarrhea, menorrhagia, hemorrhoids, helminthiasis and CNS disorders. Present study was undertaken to investigate P. hydropiper L. for heavy metals content, phytoconstituents, Phytotoxic and anthelmintic activities to explore its toxicological and pharmacological potentials and rationalize its ethnomedicinal uses. Plant crude powder, methanolic extract, fractions and soil samples were analyzed for heavy metals using atomic absorption spectrophotometer. Qualitative phytochemical analysis of the plant extracts was carried out for the existence of alkaloids, flavonoids, glycosides, anthraquinones, saponins, terpenoids, sterols and tannins. Radish seeds phytotoxicity assay was used to study phytotoxic action of plant extracts. Pheretima posthuma and Ascaridia galli were used to study anthelmintic potential of the plant using albendazole and levamisole HCl as standard drugs. Plant crude powder, methanolic extract (Ph.Cr), its subsequent fractions; n-hexane (Ph.Hex), chloroform (Ph.Chf), ethyl acetate (Ph.EtAc), n-Butanol (Ph.Bt), aqueous (Ph.Aq), saponins (Ph.Sp) and soil samples were found to contain copper (Cu), iron (Fe), chromium (Cr), zinc (Zn), lead (Pb), nickel (Ni), cadmium (Cd) and lead (Pb) in different concentrations. In crude powder of the plant, heavy metals concentrations were within WHO specified limits, whereas different fractions and soil samples exhibited high metals content. Ph.Cr was tested positive for the presence of alkaloids, flavonoids, saponins, tannins, triterpenoids and anthraquinone glycosides. Among different fractions Ph.EtAc, Ph.Sp, Ph.Chf and Ph.Bt were most effective causing 89.32, 89.25, 86.68 and 85.32% inhibition of seeds in phytotoxicity assay, with IC50 values of 50, 60, 35 and 100 μg/ml respectively. In anthelmintic study, Ph.Sp, Ph.Chf, Ph.EtAc and Ph.Cr were most effective against P. posthuma at 10 mg
Xia, Chuan
2015-06-11
Due to their unique structural features including well-defined interior voids, low density, low coefficients of thermal expansion, large surface area and surface permeability, hollow micro/nanostructured transition metal sulfides with high conductivity have been investigated as new class of electrode materials for pseudocapacitor applications. Herein, we report a novel self-templating strategy to fabricate well-defined single and double-shell NiCo2S4 hollow spheres, as a promising electrode material for pseudocapacitors. The surfaces of the NiCo2S4 hollow spheres consist of self-assembled 2D mesoporous nanosheets. This unique morphology results in a high specific capacitance (1257 F g-1 at 2 A g-1), remarkable rate performance (76.4% retention of initial capacitance from 2 A g-1 to 60 A g-1) and exceptional reversibility with a cycling efficiency of 93.8% and 87% after 10,000 and 20,000 cycles, respectively, at a high current density of 10 A g-1. The cycling stability of our ternary chalcogenides is comparable to carbonaceous electrode materials, but with much higher specific capacitance (higher than any previously reported ternary chalcogenide), suggesting that these unique chalcogenide structures have potential application in next-generation commercial pseudocapacitors.
Jiang, Li; Zhang, Bodong; Médard, Guillaume; Seitsonen, Ari Paavo; Haag, Felix; Allegretti, Francesco; Reichert, Joachim; Kuster, Bernhard; Barth, Johannes V; Papageorgiou, Anthoula C
2017-12-01
By means of scanning tunnelling microscopy (STM), complementary density functional theory (DFT) and X-ray photoelectron spectroscopy (XPS) we investigate the binding and self-assembly of a saturated molecular layer of model N -heterocyclic carbene (NHC) on Cu(111), Ag(111) and Au(111) surfaces under ultra-high vacuum (UHV) conditions. XPS reveals that at room temperature, coverages up to a monolayer exist, with the molecules engaged in metal carbene bonds. On all three surfaces, we resolve similar arrangements, which can be interpreted only in terms of mononuclear M(NHC) 2 (M = Cu, Ag, Au) complexes, reminiscent of the paired bonding of thiols to surface gold adatoms. Theoretical investigations for the case of Au unravel the charge distribution of a Au(111) surface covered by Au(NHC) 2 and reveal that this is the energetically preferential adsorption configuration.
Mohammed, Fiaz S.
Global carbon dioxide (CO2) emissions have steadily risen over the last 50 years, with 34 billion tons of CO2 released in 2009 alone. Its potential as a greenhouse gas has negatively affected of our lives and environment by the resulting ocean acidification and climate change. To mitigate atmospheric CO2, various strategies have been implemented for CO2 separation, capture, storage and use as a chemical feedstock. The use of CO2 in various chemical industries is attractive as its non-flammable, non-toxic, and relatively inert properties have made it an inherently safer alternative to traditional organic solvents, as well as, a greener carbon feedstock. Also, the accessible critical properties, appreciable critical density, high diffusivity and tunable thermophysical properties make liquid and supercritical CO2 an attractive solvent for industrial applications. In recent years, significant progress has been made in the field of tunable solvent media by employing the reversible reaction of CO2 with amines to produce carbamates. This class of compounds possesses ionic properties that are significantly different from their amines resulting in a non-ionic to ionic switching mechanism that provides for switchable solvent properties, reversible surfactants, low molecular weight organogelators and stimuli responsive materials. The focus of this dissertation is therefore the implementation of the reversible CO2—amine reaction for the formation of smart surfaces, greener amine protection mechanisms, and cationic metallic nanoparticle synthesis. Chapter 2 of this dissertation demonstrates the reversible reaction of CO2 with amine-containing self-assembled monolayers to yield "smart" surfaces that undergo a reversible change in structure, charge, and wettability upon reaction with CO2. The formation carbamate esters are also a widely implemented mechanism for amine protection during organic synthesis. However, traditional methods of protection incur increased solvent use and
Acosta, J.A.; Faz, A.; Kalbitz, K.; Jansen, B.; Martínez-Martínez, S.
2011-01-01
Street dust has been sampled from six different types of land use of the city of Murcia (Spain). The samples were fractionated into eleven particle size fractions (<2, 2-10, 10-20, 20-50, 50-75, 75-106, 106-150, 150-180, 180-425, 425-850 μm and 850-2000 μm) and analyzed for Pb, Cu, Zn and Cd. The
DEFF Research Database (Denmark)
Chomchoei, Roongrat; Miró, Manuel; Hansen, Elo Harald
2005-01-01
to conventional batch methods, this fully automated approach furthermore offers the potentials of a variety of operational extraction protocols. Employing the three-step sequential extraction BCR scheme to a certified homogeneous soil reference material (NIST, SRM 2710), this communication investigates four...
Bagheri, Zahra; Bakhtiari, Alireza Riyahi; Savabieasfahani, Mozhgan
2014-03-01
Cadmium (Cd) and lead (Pb) were determined in three species of mollusks and associated sediment. Samples were collected from two locations along the intertidal zone of the Persian Gulf near Bandar Abbas. The study was conducted during the spring of 2011, 10 sediment samples and 15 mollusks from each of the following species: Saccostrea cucullata, Solen brevis, and Callista umbonella, were simultaneously collected. Soft tissue, shell, and sediment were tested for metals using an atomic absorption spectrophotometer. Geochemical fractions of the sediment were examined for metals using a sequential extraction technique. Our results indicate that over half of Cd and Pb in the sediment had natural origins. Independent sample t test showed statistically significant (p < 0.05) inter-tissue differences in accumulation of Cd and Pb. Soft tissue of C. umbonella contained highest levels of Cd. Pb accumulation was highest in S. brevis shell. Significant correlations (p < 0.05) were found between Cd in the soft tissue of C. umbonella and its levels in the geochemical fractions of the sediment. Lead levels in the resistant geochemical fractions of the sediment and S. brevis shell were significantly correlated. Our results suggest that soft tissue of C. umbonella and shell of S. brevis are reliable biomonitoring tools for Cd and Pb, respectively.
Maqsood, Saba; Rashid, Muhammad; Din, Fasih Ud; Saddique, M. Bilal; Laref, A.
2018-03-01
The cubic XFeO3 (X = Sr, Ba) perovskite oxides are studied for their thermodynamic stability in the ferromagnetic phase by using density functional theory calculations. We also explore the elastic properties of these compounds in terms of elastic constants C ij, bulk modulus B, shear modulus G, anisotropy factor A, Poisson's ratio ν and the B/ G ratio. The electronic properties are examined to elucidate the magnetic order, and the thermoelectric properties of XFeO3 (X = Sr, Ba) materials are also presented. The modified Becke-Johnson local density approximation scheme has been used to compute the electronic band structure and density of states, which show that these materials are half-metallic ferromagnetic. We study the magnetic properties by computing the crystal field energy (ΔCF), John-Teller energy (ΔJT) and the exchange splitting energies Δx( d) and Δx( pd). Our results indicate that strong hybridization causes a decrease in the magnetic moment of Fe, which then produces permanent magnetic moments in the nonmagnetic sites.
Yin, Wenjie; Bai, Lijie; Zhu, Yuzhen; Zhong, Shuxian; Zhao, Leihong; Li, Zhengquan; Bai, Song
2016-09-07
The construction of a p-n heterojunction is an efficient strategy to resolve the limited light absorption and serious charge-carrier recombination in semiconductors and enhance the photocatalytic activity. However, the promotion effect is greatly limited by poor interfacial charge transfer efficiency as well as reduced redox ability of charge carriers. In this work, we demonstrate that the embedding of metal Pd into the interface between n-type C3N4 and p-type Cu2O can further enhance the interfacial charge transfer and increase the redox ability of charge carriers through the design of the C3N4-Pd-Cu2O stack nanostructure. The embedded Pd nanocubes in the stack structure not only trap the charge carriers from the semiconductors in promoting the electron-hole separation but also act as a Z-scheme "bridge" in keeping the strong reduction/oxidation ability of the electrons/holes for surface reactions. Furthermore, Pd nanocubes also increase the bonding strength between the two semiconductors. Enabled by this unique design, the hydrogen evolution achieved is dramatically higher than that of its counterpart C3N4-Cu2O structure without Pd embedding. The apparent quantum efficiency (AQE) is 0.9% at 420 nm for the designed C3N4-Pd-Cu2O. This work highlights the rational interfacial design of heterojunctions for enhanced photocatalytic performance.
International Nuclear Information System (INIS)
Bujtas, K.; Csillag, J.
1999-01-01
In a pot experiment, availabilities of Cd, Cr, Ni, Pb, and Zn added to the soil as metal nitrates or as enrichment of sewage sludge were evaluated by comparing concentrations of their total potentially available, presumably plant-available and directly plant-available forms in the soil. At excessively increasing soil contamination, the plant-available concentrations increased more than the total soil contents, thus the relative availabilities of the metals increased. This was reflected in the amounts taken up by the young maize test plants and in the plant/soil transfer factors. Transfer factors calculated for the 'plant-available' soil metal contents depended less on the contamination level than those based on total soil metal contents. Refs. 8 (author)
DEFF Research Database (Denmark)
van Leeuwen, Theo
2013-01-01
This chapter presents a framework for analysing colour schemes based on a parametric approach that includes not only hue, value and saturation, but also purity, transparency, luminosity, luminescence, lustre, modulation and differentiation.......This chapter presents a framework for analysing colour schemes based on a parametric approach that includes not only hue, value and saturation, but also purity, transparency, luminosity, luminescence, lustre, modulation and differentiation....
Kong, Shaofei; Lu, Bing; Ji, Yaqin; Zhao, Xueyan; Bai, Zhipeng; Xu, Yonghai; Liu, Yong; Jiang, Hua
2012-03-01
15 road and 14 soil dust samples were collected from an oilfield city, Dongying, from 11/2009-4/2010 and analyzed by inductively coupled plasma-mass spectroscopy (ICP-MS) for V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd and Pb within PM(2.5), PM(10) and PM(100) fractions synchronously. Metal concentrations, sources and human health risk were studied. Results showed that both soil and road dust exhibited higher values for Mn and Zn and lower values for Co and Cd for the three fractions. Mass concentration ratios of PM(2.5)/PM(10) and PM(10)/PM(100) for metals in road and soil dust indicate that most of the heavy metals tend to concentrate in fine particles. Geoaccumulation index and enrichment factors analysis showed that Cu, Zn and Cd exhibited moderate or heavy contamination and significant enrichment, indicating the influence of anthropogenic sources. Vanadium, Cr, Mn and Co were mostly not enriched and were mainly influenced by crustal sources. For Ni, As and Pb, they ranged from not enriched to moderately enriched and were influenced by both crustal materials and anthropogenic sources. The conclusions were confirmed by multivariate analysis methods. Principle component analysis revealed that the major sources were vehicle emission, industrial activities, coal combustion, agricultural activities and crustal materials. The risk assessment results indicated that metal ingestion appeared to be the main exposure route followed by dermal contact. The most likely cause for cancer and other health risks are both the fine particles of soil and road dusts. This journal is © The Royal Society of Chemistry 2012
Sharma, Preeti; Melkania, Uma
2018-02-06
In the present study, the effect of heavy metals (lead, mercury, copper, and chromium) on the hydrogen production from the organic fraction of municipal solid waste (OFMSW) was investigated using co-culture of facultative anaerobes Enterobacter aerogenes and E. coli. Heavy metals were applied at concentration range of 0.5, 1, 2, 5, 10, 20, 50 and 100 mg/L. The results revealed that lead, mercury, and chromium negatively affected hydrogen production for the range of concentrations applied. Application of copper slightly enhanced hydrogen production at low concentration and resulted in the hydrogen yield of 36.0 mLH 2 /gCarbo initial with 10 mg/L copper supplementation as compared to 24.2 mLH 2 /gCarbo initial in control. However, the higher concentration of copper (>10 mg/L) declined hydrogen production. Hydrogen production inhibition potential of heavy metals can be arranged in the following increasing order: Cu 2+ hydrogen production. Therefore, it is essential to remove the toxic heavy metals prior to anaerobic digestion. Copyright © 2018. Published by Elsevier Ltd.
Acosta, J.A.; Faz, A.; Kalbitz, K.; Jansen, B.; Martínez-Martínez, S.
2014-01-01
Dust samples were collected from urban, suburban, industrial, highways, and natural sites from the vicinity of Murcia City, Spain. Chemical and physical properties were determined as well as the partitioning of the heavy metals Cu, Pb, Zn and Cd over exchangeable pools, association with carbonates,
Oonk, Paul B.H.; Tsikos, Harilaos; Mason, Paul R.D.; Henkel, Susann; Staubwasser, Michael; Fryer, Lindi; Poulton, Simon W.; Williams, Helen M.
2017-01-01
Iron formations (IFs) are important geochemical repositories that provide constraints on atmospheric and ocean chemistry, prior to and during the onset of the Great Oxidation Event. Trace metal abundances and their Mo-Cr-U isotopic ratios have been widely used for investigating ocean redox processes
Delshab, Hossein; Farshchi, Parvin; Keshavarzi, Behnam
2017-02-15
In this study, total concentration and speciation of heavy metals in sediments of the Asaluyeh, one of the Iran's largest commercial ports, are investigated. 48 sediment samples were collected and analyzed for trace and major elements. Sediment quality guidelines along with calculated enrichment factors and trace metal profiles indicate that Asaluyeh port is threated by contamination, especially with respect to Hg and Cu. Normalization to Sc indicated high enrichment factors in the sediments following the decreasing order of: Hg>Cu>As>Ni>Zn>Pb≈Cr≈Mn>Co≈V≈Fe≈Al. Hg displayed the greatest potential ecological risk factor among sampling stations. The results of sequential extraction procedure revealed that in some stations >50% of Mn, V, Cu and Zn occur in potentially mobile phases and therefore are more readily mobilized in the sediments of the study area. Copyright © 2016 Elsevier Ltd. All rights reserved.
STALS, Mark; CARLEER, Robert; REGGERS, Guy; Schreurs, Sonja; YPERMAN, Jan
2010-01-01
Flash pyrolysis of heavy metal contaminated hardwoods originating from phytoremediation is studied. Different kinds of hardwoods, i.e. Salix fragilis (crack willow), Salix jorunn ("Jorunn" willow) and Populus grimminge (Grimminge poplar) are compared in a preliminary phase. Salix fragilis scores the best on both remediation capabilities and pyrolysis characteristics. Therefore, this cultivar is chosen for in-depth research. S. fragilis stems, leaves and stems mixed with leaves are pyrolysed. ...
J.K. Hoogland (Jiri); C.D.D. Neumann
2000-01-01
textabstractIn this article we present a new approach to the numerical valuation of derivative securities. The method is based on our previous work where we formulated the theory of pricing in terms of tradables. The basic idea is to fit a finite difference scheme to exact solutions of the pricing
Energy Technology Data Exchange (ETDEWEB)
Auberdiac, P.; Cartier, L.; Malkoun, N.; Chauleur, C.; De Laroche, G.; Magne, N. [Departement de radiotherapie, institut de cancerologie de la Loire, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex (France); Chargari, C. [Service d' oncologie radiotherapie, hopital d' instruction des armees du Val-de-Grace, 74, boulevard de Port-Royal, 75230 Paris cedex 5 (France); Melis, A.; Jacquin, J.P. [Departement d' oncologie medicale, institut de cancerologie de la Loire, 108 bis, avenue Albert-Raimond, BP 60008, 42271 Saint-Priest-en-Jarez cedex (France)
2011-12-15
Normo-fractionated radiotherapy is standard for adjuvant management of patients treated with breast conservative surgery for breast cancer. However, many elderly patients are not eligible to such strategy, either because of concurrent diseases, or because the tumor is inoperable. Several protocols of exclusive radiotherapy have been reported in the literature, frequently using hypo-fractionated radiotherapy and endocrine therapy. We report a case of a patient treated with exclusive endocrine and radiotherapy and address the state of the art on hypo-fractionated schemes for the management of elderly breast cancer patients. While hypo-fractionated radiotherapy does not compromise the oncologic or cosmetic outcome, there is no prospective data that assesses the place of radiotherapy for the exclusive treatment of elderly patients. This strategy should be further assessed in clinical randomized trial. (authors)
Loeschner, Katrin; Harrington, Chris F; Kearney, Jacque-Lucca; Langton, David J; Larsen, Erik H
2015-06-01
Hip replacements are used to improve the quality of life of people with orthopaedic conditions, but the use of metal-on-metal (MoM) arthroplasty has led to poor outcomes for some patients. These problems are related to the generation of micro- to nanosized metal wear particles containing Cr, Co or other elements, but the current analytical methods used to investigate the processes involved do not provide sufficient information to understand the size or composition of the wear particles generated in vivo. In this qualitative feasibility study, asymmetric flow field-flow fractionation (AF(4)) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was used to investigate metal protein binding and the size and composition of wear metal particles present in serum and hip aspirates from MoM hip replacement patients. A well-established HPLC anion exchange chromatography (AEC) separation system coupled to ICP-MS was used to confirm the metal-protein associations in the serum samples. Off-line single particle ICP-MS (spICP-MS) analysis was used to confirm the approximate size distribution indicated by AF(4) of the wear particles in hip aspirates. In the serum samples, AF(4) -ICP-MS suggested that Cr was associated with transferrin (Tf) and Co with albumin (Alb) and an unidentified species; AEC-ICP-MS confirmed these associations and also indicated an association of Cr with Alb. In the hip aspirate sample, AF(4)-ICP-MS suggested that Cr was associated with Alb and Tf and that Co was associated with Alb and two unidentified compounds; AEC analysis confirmed the Cr results and the association of Co with Alb and a second compound. Enzymatic digestion of the hip aspirate sample, followed by separation using AF(4) with detection by UV absorption (280 nm), multi-angle light scattering and ICP-MS, suggested that the sizes of the Cr-, Co- and Mo-containing wear particles in a hip aspirate sample were in the range 40-150 nm. Off-line spICP-MS was used to confirm these
Wang, Bin; Qu, Shengguan; Li, Xiang-Long
2017-01-01
This paper reports the development of high volume fraction SiCP/Al composite-bismuthate glass multilayer films optics Au-mirror with high reflectivity in a wavelength range of 760 to 1000 nm. Multilayer films were fabricated using an radio frequency-magnetron sputtering deposition system. The measured reflectivity of Ta2O5/SiO2/Au/Cr metal plus dielectric films optics Au-mirror could reach up to ≥97%. Then, on the basis of experiments, a Φ75-mm high volume fraction SiCP/Al composite-bismuthate glass multilayer optical Au-mirror for a wavelength range of 760 to 1000 nm was manufactured. The tested results indicate that a peak-to-valley value of 0.854λ (λ=632.8 nm) was achieved on the Au-mirror surface, and the slope deviation error for the flat surface was lower than 0.153λ root mean square. The surface roughness of Ta2O5/SiO2/Au/Cr multilayer thin films was 1.30 nm (Ra).
Directory of Open Access Journals (Sweden)
Daniel López
2017-10-01
Full Text Available Catalytic steam gasification of extra-heavy oil (EHO fractions was studied using functionalized aluminosilicates, with NiO, MoO3, and/or CoO nanoparticles with the aim of evaluating the synergistic effect between active phase and the support in heavy oil on-site upgrading. Catalysts were characterized by chemical composition through X-ray Fluorescence, surface area, and pore size distribution through N2 adsorption/desorption, catalyst acidity by temperature programmed desorption (TPD, and metal dispersion by pulse H2 chemisorption. Batch adsorption experiments and catalytic steam gasification of adsorbed heavy fractions was carried out by thermogravimetric analysis and were performed with heavy oil model solutions of asphaltenes and resins (R–A in toluene. Effective activation energy estimation was used to determine the catalytic effect of the catalyst in steam gasification of Colombian EHO. Additionally, R–A decomposition under inert atmosphere was conducted for the evaluation of oil components reactions with active phases and steam atmosphere. The presence of a bimetallic active phase Inc.reases the decomposition of the heavy compounds at low temperature by an increase in the aliphatic chains decomposition and the dissociation of heteroatoms bonds. Also, coke formation after steam gasification process is reduced by the application of the bimetallic catalyst yielding a conversion greater than 93%.
Cena, L G; Chisholm, W P; Keane, M J; Chen, B T
2015-01-01
A field study was conducted to estimate the amount of Cr, Mn, and Ni deposited in the respiratory system of 44 welders in two facilities. Each worker wore a nanoparticle respiratory deposition (NRD) sampler during gas metal arc welding (GMAW) of mild and stainless steel and flux-cored arc welding (FCAW) of mild steel. Several welders also wore side-by-side NRD samplers and closed-face filter cassettes for total particulate samples. The NRD sampler estimates the aerosol's nano-fraction deposited in the respiratory system. Mn concentrations for both welding processes ranged 2.8-199 μg/m3; Ni concentrations ranged 10-51 μg/m3; and Cr concentrations ranged 40-105 μg/m3. Cr(VI) concentrations ranged between 0.5-1.3 μg/m3. For the FCAW process the largest concentrations were reported for welders working in pairs. As a consequence this often resulted in workers being exposed to their own welding fumes and to those generated from the welding partner. Overall no correlation was found between air velocity and exposure (R2 = 0.002). The estimated percentage of the nano-fraction of Mn deposited in a mild-steel-welder's respiratory system ranged between 10 and 56%. For stainless steel welding, the NRD samplers collected 59% of the total Mn, 90% of the total Cr, and 64% of the total Ni. These results indicate that most of the Cr and more than half of the Ni and Mn in the fumes were in the fraction smaller than 300 nm.
Cena, L. G.; Chisholm, W. P.; Keane, M. J.; Chen, B. T.
2016-01-01
A field study was conducted to estimate the amount of Cr, Mn, and Ni deposited in the respiratory system of 44 welders in two facilities. Each worker wore a nanoparticle respiratory deposition (NRD) sampler during gas metal arc welding (GMAW) of mild and stainless steel and flux-cored arc welding (FCAW) of mild steel. Several welders also wore side-by-side NRD samplers and closed-face filter cassettes for total particulate samples. The NRD sampler estimates the aerosol's nano-fraction deposited in the respiratory system. Mn concentrations for both welding processes ranged 2.8–199 μg/m3; Ni concentrations ranged 10–51 μg/m3; and Cr concentrations ranged 40–105 μg/m3. Cr(VI) concentrations ranged between 0.5–1.3 μg/m3. For the FCAW process the largest concentrations were reported for welders working in pairs. As a consequence this often resulted in workers being exposed to their own welding fumes and to those generated from the welding partner. Overall no correlation was found between air velocity and exposure (R2 = 0.002). The estimated percentage of the nano-fraction of Mn deposited in a mild-steel-welder's respiratory system ranged between 10 and 56%. For stainless steel welding, the NRD samplers collected 59% of the total Mn, 90% of the total Cr, and 64% of the total Ni. These results indicate that most of the Cr and more than half of the Ni and Mn in the fumes were in the fraction smaller than 300 nm. PMID:25985454
Contreras, M; Pérez-López, R; Gázquez, M J; Morales-Flórez, V; Santos, A; Esquivias, L; Bolívar, J P
2015-11-01
The industry of phosphoric acid produces a calcium-rich by-product known as phosphogypsum, which is usually stored in large stacks of millions of tons. Up to now, no commercial application has been widely implemented for its reuse because of the significant presence of potentially toxic contaminants. This work confirmed that up to 96% of the calcium of phosphogypsum could be recycled for CO2 mineral sequestration by a simple two-step process: alkaline dissolution and aqueous carbonation, under ambient pressure and temperature. This CO2 sequestration process based on recycling phosphogypsum wastes would help to mitigate greenhouse gasses emissions. Yet this work goes beyond the validation of the sequestration procedure; it tracks the contaminants, such as trace metals or radionuclides, during the recycling process in the phosphogypsum. Thus, most of the contaminants were transferred from raw phosphogypsum to portlandite, obtained by dissolution of the phosphogypsum in soda, and from portlandite to calcite during aqueous carbonation. These findings provide valuable information for managing phosphogypsum wastes and designing potential technological applications of the by-products of this environmentally-friendly proposal. Copyright © 2015 Elsevier Ltd. All rights reserved.
Fonseca, Raúl O. C.; Brückel, Karoline; Bragagni, Alessandro; Leitzke, Felipe P.; Speelmanns, Iris M.; Wainwright, Ashlea N.
2017-11-01
Although Earth's continental crust is thought to derive from melting of the Earth's mantle, how the crust has formed and the timing of its formation are not well understood. The main difficulty in understanding how the crust was extracted from the Earth's mantle is that most isotope systems recorded in mantle rocks have been disturbed by crustal recycling, metasomatic activity and dilution of the signal by mantle convection. In this regard, important age constraints can be obtained from Re-Os model ages in platinum group minerals (PGM), as Re-poor and Os-rich PGM show evidence of melting events up to 4.1 Ga. To constrain the origin of the Re-Os fractionation and Os isotope systematics of natural PGM, we have investigated the linkage between sulfide and PGM grains of variable composition via a series of high-temperature experiments carried out at 1 bar. We show that with the exception of laurite, all experimentally-produced PGM, in particular Pt3Fe (isoferroplatinum) and Pt-Ir metal grains, are systematically richer in Re than their sulfide precursors and will develop radiogenic 187Os /188Os signatures over time relative to their host base metal sulfides. Cooling of an PGM-saturated sulfide assemblage shows a tendency to amplify the extent of Re-Os fractionation between PGM and the different sulfide phases present during cooling. Conversely, laurite grains (RuS2) are shown to accept little to no Re in them and their Os isotope composition changes little over time as a result. Laurite is therefore the PGM that provides the most robust Re-depletion ages in mantle lithologies. Our results are broadly consistent with observations made on natural PGM, where laurites are systematically less radiogenic than Pt-rich PGM. These experimental results highlight the need for the acquisition of large datasets for both mantle materials and ophiolite-derived detrital grains that include measurements of the Os isotope composition of minerals rich in highly siderophile elements at
Energy Technology Data Exchange (ETDEWEB)
Villaescusa-Celaya, Julio A; Gutierrez-Galindo, Efrain A; Flores-Munoz, Gilberto [Instituto de Investigaciones Oceanologicas, Universidad Autonoma de Baja California, Ensenada, B.C., (Mexico)
1997-03-01
The concentrations of the heavy metals Cu, Zn, Ni, Cr, Pb, Cd, Ag, Mn and Fe in the different geochemical sediment fractions are determined in this study, as a means of assessing the impact of residual wastewater on the coastal sediments of the region. During an oceanographic cruise in April 1992 (ECOBAC IV), 20 samples of surface sediments were collected from the coastal shelf of the border region between Baja California (Mexico) and California (USA), The sediment samples were subjected to a sequential extraction procedure designed to obtain the geochemical fractions defined as: exchangeable (F1), carbonates (F2), Fe and Mn oxyhydroxides (F3), organic matter/sulfides (F4) and residual or lithogenic (F5). The operational speciation of the metals indicates that the principal phases in the sediments that accumulate metal are the detrital or lithogenic matrix, the Fe and Mn oxyhydroxides and the organic Matter/sulfides, in this order. In general, the spatial distribution of the heavy metals in the reactive phase (defined as the sum of F1-F4) tended to increase in concentration in offshore sediments. The heavy metals in the reactive phase are apparently controlled by the concentration of reactive iron in the sediments, except for Pb, Cd and Ag, suggesting that the latter elements are controlled by other processes, such as particulate matter of biogenic origin. In contrast, the spatial distribution of heavy metals in the detrital phase behaved inversely, that is, the greatest concentrations of metals are found close to the coast off the wastewater treatment plant at Punta Bandera, Baja California. The average concentrations of total metals (sum of F1-F5) were 7.6, 40, 21, 68, 428, 11, 0.10 and 0.025 {mu}g{sup -}1 for Cu, Zn, Ni, Cr, Mn, Pb, Cd and Ag, respectively, and 2.3% for Fe. These concentrations are similar to those reported for uncontaminated reference sediments from southern California, indicating that a large amount of pollutants from the effluent of residual
Scheme Program Documentation Tools
DEFF Research Database (Denmark)
Nørmark, Kurt
2004-01-01
This paper describes and discusses two different Scheme documentation tools. The first is SchemeDoc, which is intended for documentation of the interfaces of Scheme libraries (APIs). The second is the Scheme Elucidator, which is for internal documentation of Scheme programs. Although the tools...... as named functions in Scheme. Finally, the Scheme Elucidator is able to integrate SchemeDoc resources as part of an internal documentation resource....
Additive operator-difference schemes splitting schemes
Vabishchevich, Petr N
2013-01-01
Applied mathematical modeling isconcerned with solving unsteady problems. This bookshows how toconstruct additive difference schemes to solve approximately unsteady multi-dimensional problems for PDEs. Two classes of schemes are highlighted: methods of splitting with respect to spatial variables (alternating direction methods) and schemes of splitting into physical processes. Also regionally additive schemes (domain decomposition methods)and unconditionally stable additive schemes of multi-component splitting are considered for evolutionary equations of first and second order as well as for sy
Intracellular Cadmium Isotope Fractionation
Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.
2011-12-01
Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.
Directory of Open Access Journals (Sweden)
Adriana Barbosa Araújo
2002-12-01
Full Text Available In this work the metal distribution and exchange constants between metal species and aquatic humic fractions with different molecular sizes were studied. The aquatic humic substances (AHS were extracted by XAD-8 resin from water sample collected from Itapitanguí river, São Paulo State, Brazil. The AHS were fractionated in six fractions with different molecular sizes (>100 - <5 kDa and characterized by several techniques. Molar ratios H/C suggested higher aromaticity for fractions F1 and F6 whereas molar ratios C/N didn´t show any differences regarding the humification degree between the fractions. The UV-Vis absorbance a254/a436 ratio showed higher results for F4 and F5, probably by less condensed features. FTIR studies showed high similarity in the functional groups in the fractions. The highest percentage of traces of Co, Al, Fe, Mn, Cu, Zn and Ni (determined by ICP-AES was preferably complexed by fractions F3 and F4 with a greater amount of dissolved organic carbon (DOC. In addition, the exchange constants, determined by ultrafiltration method, showed complexes AHS-Fe and AHS-Al with higher stability than complexes AHS-Co in all fractions.
DEFF Research Database (Denmark)
Wang, Jianhua; Hansen, Elo Harald
2003-01-01
a polytetrafluoroethylene (PTFE) knotted reactor (KR), solvent extraction-back extraction and hydride/vapor generation. It also addresses a novel, robust approach, whereby the protocol of SI-LOV-bead injection (BI) on-line separation and pre-concentration of ultra-trace levels of metals by a renewable microcolumn...
Gitari, M W; Akinyemi, S A; Ramugondo, L; Matidza, M; Mhlongo, S E
2018-04-30
The economic benefits of mining industry have often overshadowed the serious challenges posed to the environments through huge volume of tailings generated and disposed in tailings dumps. Some of these challenges include the surface and groundwater contamination, dust, and inability to utilize the land for developmental purposes. The abandoned copper mine tailings in Musina (Limpopo province, South Africa) was investigated for particle size distribution, mineralogy, physicochemical properties using arrays of granulometric, X-ray diffraction, and X-ray fluorescence analyses. A modified Community Bureau of Reference (BCR) sequential chemical extraction method followed by inductively coupled plasma mass spectrometry/atomic emission spectrometry (ICP-MS/AES) technique was employed to assess bioavailability of metals. Principal component analysis was performed on the sequential extraction data to reveal different loadings and mobilities of metals in samples collected at various depths. The pH ranged between 7.5 and 8.5 (average ≈ 8.0) indicating alkaline medium. Samples composed mostly of poorly grated sands (i.e. 50% fine sand) with an average permeability of about 387.6 m/s. Samples have SiO 2 /Al 2 O 3 and Na 2 O/(Al 2 O 3 + SiO 2 ) ratios and low plastic index (i.e. PI ≈ 2.79) suggesting non-plastic and very low dry strength. Major minerals were comprised of quartz, epidote, and chlorite while the order of relative abundance of minerals in minor quantities is plagioclase > muscovite > hornblende > calcite > haematite. The largest percentage of elements such as As, Cd and Cr was strongly bound to less extractable fractions. Results showed high concentration and easily extractable Cu in the Musina Copper Mine tailings, which indicates bioavailability and poses environmental risk and potential health risk of human exposure. Principal component analysis revealed Fe-oxide/hydroxides, carbonate and clay components, and copper ore process
Maria Klimikova
2010-01-01
Understanding the reasons of the present financial problems lies In understanding the substance of fractional reserve banking. The substance of fractional banking is in lending more money than the bankers have. Banking of partial reserves is an alternative form which links deposit banking and credit banking. Fractional banking is causing many unfavorable economic impacts in the worldwide system, specifically an inflation.
Jara-Marini, Martín E; García-Camarena, Raúl; Gómez-Álvarez, Agustín; García-Rico, Leticia
2015-07-01
The aim of this study was to evaluate Fe and Mn distribution in geochemical fractions of the surface sediment of four oyster culture sites in the Sonora coast, Mexico. A selective fractionation scheme to obtain five fractions was adapted for the microwave system. Surface sediments were analyzed for carbonates, organic matter contents, and Fe and Mn in geochemical fractions. The bulk concentrations of Fe ranged from 10,506 to 21,918 mg/kg (dry weight, dry wt), and the bulk concentrations of Mn ranged from 185.1 to 315.9 mg/kg (dry wt) in sediments, which was low and considered as non-polluted in all of the sites. The fractionation study indicated that the major geochemical phases for the metals were the residual, as well as the Fe and Mn oxide fractions. The concentrations of metals in the geochemical fractions had the following order: residual > Fe and Mn oxides > organic matter > carbonates > interchangeable. Most of the Fe and Mn were linked to the residual fraction. Among non-residual fractions, high percentages of Fe and Mn were linked to Fe and Mn oxides. The enrichment factors (EFs) for the two metals were similar in the four studied coasts, and the levels of Fe and Mn are interpreted as non-enrichment (EF < 1) because the metals concentrations were within the baseline concentrations. According to the environmental risk assessment codes, Fe and Mn posed no risk and low risk, respectively. Although the concentrations of Fe and Mn were linked to the residual fraction, the levels in non-residual fractions may significantly result in the transference of other metals, depending on several physico-chemical and biological factors.
DEFF Research Database (Denmark)
Wagner, Stephan; Legros, Samuel; Löschner, Katrin
2015-01-01
content by asymmetric flow-field flow fractionation coupled to a multi-angle light scattering detector and an inductively coupled plasma mass spectrometer. Following the proposed generic procedure SiO2-ENPs were separated from a tomato soup. Two potential sample preparation methods were tested these being...
Energy Technology Data Exchange (ETDEWEB)
Exner, A.; Theisen, M.; Panne, U.; Niessner, R. [Inst. for Hydrochemistry, Technical University of Munich (Germany)
2000-02-01
To assess the structural variability of colloidal humic substances and the associated heavy metals an off-line coupling of asymmetric flow field-flow fractionation (AF{sup 4}) with total-reflection X-ray fluorescence analysis (TXRF) is presented. AF{sup 4} allows a rather gentle separation of colloids with a minimum of interference and artifacts as no shear forces, drying, or interactions with a stationary phase are involved. After a calibration with suitable polymer particles of known molecular weight, the molecular weight distribution of colloidal humic substances between 1 and 10{sup 3} kDa can be assessed with AF{sup 4}. The combination with TXRF permits a simultaneous multielement analysis after preconcentration of samples on the AF{sup 4} channel using an optimized buffer. The analysis of seepage and sewage water sample and a sewage sludge sample yielded continuous distributions of the molecular weight and the associated heavy metals. The potential of AF{sup 4}-TXRF coupling for the study of metal ion exchange equilibria with colloids was demonstrated by spiking seepage water with various heavy metals and subsequent AF{sup 4}-TXRF analysis of the heavy metals bound to the colloidal fraction (Cu, Cr, Zn, Ni, Co). (orig.)
Exner, A; Theisen, M; Panne, U; Niessner, R
2000-02-01
To assess the structural variability of colloidal humic substances and the associated heavy metals an off-line coupling of asymmetric flow field-flow fractionation (AF4) with total-reflection X-ray fluorescence analysis (TXRF) is presented. AF4 allows a rather gentle separation of colloids with a minimum of interference and artifacts as no shear forces, drying, or interactions with a stationary phase are involved. After a calibration with suitable polymer particles of known molecular weight, the molecular weight distribution of colloidal humic substances between 1 and 10(3) kDa can be assessed with AF4. The combination with TXRF permits a simultaneous multielement analysis after preconcentration of samples on the AF4 channel using an optimized buffer. The analysis of seepage and sewage water sample and a sewage sludge sample yielded continuous distributions of the molecular weight and the associated heavy metals. The potential of AF4-TXRF coupling for the study of metal ion exchange equilibria with colloids was demonstrated by spiking seepage water with various heavy metals and subsequent AF4-TXRF analysis of the heavy metals bound to the colloidal fraction (Cu, Cr, Zn, Ni, Co).
Povstenko, Yuriy
2015-01-01
This book is devoted to fractional thermoelasticity, i.e. thermoelasticity based on the heat conduction equation with differential operators of fractional order. Readers will discover how time-fractional differential operators describe memory effects and space-fractional differential operators deal with the long-range interaction. Fractional calculus, generalized Fourier law, axisymmetric and central symmetric problems and many relevant equations are featured in the book. The latest developments in the field are included and the reader is brought up to date with current research. The book contains a large number of figures, to show the characteristic features of temperature and stress distributions and to represent the whole spectrum of order of fractional operators. This work presents a picture of the state-of-the-art of fractional thermoelasticity and is suitable for specialists in applied mathematics, physics, geophysics, elasticity, thermoelasticity and engineering sciences. Corresponding sections of ...
International Nuclear Information System (INIS)
Lopez, M.J.; Jellinek, J.
1999-01-01
Issues involved in fitting a semiempirical potential, such as the choice of a goodness criterion, selection of fitting quantities (properties), ascription of the degree of importance to the individual members of a fitting set, etc., all of which affect the outcome of a fitting procedure, are addressed and analyzed. The minimal maximum error fitting scheme is implemented to obtain the values of the parameters of the Gupta-type potential for nickel. The subtleties of this potential, one of which is that only four of its five parameters are independent, and their implications are pointed out and discussed. The resulting values of the parameters for nickel are analyzed and compared with those obtained in earlier studies. copyright 1999 American Institute of Physics
DEFF Research Database (Denmark)
Löschner, Katrin; Harrington, Chris F.; Kearney, Jacque-Lucca
2015-01-01
Hip replacements are used to improve the quality of life of people with orthopaedic conditions, but the use of metal-on-metal (MoM) arthroplasty has led to poor outcomes for some patients. These problems are related to the generation of micro- to nanosized metal wear particles containing Cr, Co o...
Hypo fractionated prostate treatment by volumearcotherapy modulated
International Nuclear Information System (INIS)
Clemente Gutierrez, F.; Perez Vara, C.; Prieto Villacorta, M.
2013-01-01
Several studies have been proposed over the years schemes of hypo-fractionated treatment for prostate cancer. Such schemes have been designed in order to increase local control of the disease and reduce complications. They are in addition a clear improvement from the point of view logistical and organizational for treatment centres and the patient. the hypo-fractionated treatments are possible because the ratio a/b for prostate carcinoma is comparable, and even below, the surrounding healthy tissues. This work presents the scheme adopted in our Center for the hypo-fractionated treatment of the cancer of prostate by arco therapy volumetric modulated. (Author)
Li, Xiaoxue; Xie, Keyu; Song, Long; Zhao, Mengjia; Zhang, Zhipan
2017-07-26
The effective separation of photogenerated electrons and holes in photocatalysts is a prerequisite for efficient photocatalytic water splitting. CuInS 2 (CIS) is a widely used light absorber that works properly in photovoltaics but only shows limited performance in solar-driven hydrogen evolution due to its intrinsically severe charge recombination. Here, we prepare hierarchical graphitic C 3 N 4 -supported CuInS 2 (denoted as GsC) by an in situ growth of CIS directly on exfoliated thin graphitic C 3 N 4 nanosheets (g-C 3 N 4 NS) and demonstrate efficient separation of photoinduced charge carriers in the GsC by forming the Z-scheme system for the first time in CIS-catalyzed water splitting. Under visible light illumination, the GsC features an enhanced hydrogen evolution rate up to 1290 μmol g -1 h -1 , which is 3.3 and 6.1 times higher than that of g-C 3 N 4 NS and bare-CIS, respectively, thus setting a new performance benchmark for CIS-based water-splitting photocatalysts.
Fractional diffusion in inhomogeneous media
Energy Technology Data Exchange (ETDEWEB)
Chechkin, A V [Institute for Theoretical Physics, National Science Center ' Kharkov Institute of Physics and Technology' , Akademicheskaya St. 1, Kharkov 61108 (Ukraine); Gorenflo, R [Department of Mathematics and Informatics, Free University of Berlin, Arnimallee 3, D-14195 Berlin, Dahlem (Germany); Sokolov, I M [Institute for Physics, Humboldt University of Berlin, Newtonstrasse 15, D-12489 Berlin (Germany)
2005-10-21
Starting from the continuous time random walk (CTRW) scheme with the space-dependent waiting-time probability density function (PDF) we obtain the time-fractional diffusion equation with varying in space fractional order of time derivative. As an example, we study the evolution of a composite system consisting of two separate regions with different subdiffusion exponents and demonstrate the effects of non-trivial drift and subdiffusion whose laws are changed in the course of time. (letter to the editor)
Energy Technology Data Exchange (ETDEWEB)
Gyllenhammar, Marianne (Stena Metall AB (Sweden)); Davidsson, Kent (SP Sveriges Tekniska Forskningsinstitut, Boraas (Sweden)); Jonsson, Torbjoern; Pettersson, Jesper (HTC, Chalmers Tekniska Hoegskola, Goeteborg (Sweden)); Victoren, Anders; Andersson, Hans (Metso Power AB (Sweden)); Widen, Christoffer (Lidkoepings Vaermeverk AB (Sweden))
2010-03-15
More recovered fuels have been put on the fuel market since the landfill ban of organic wastes was implemented. SLF (shredder light fraction = fluff) which is a waste from recovery of metal scrap has mostly been put on landfill until now. Due to high chlorine and metal content in this fuel there is a risk of increased deposit and corrosion problems in incineration plants. This project investigated if co-combustion with sewage sludge could reduce these problems. The purpose of the project was also to document the influence of SLF when it comes to deposits and corrosion in an incineration plant. In this project SLF has been co-combusted with normal waste with and without sewage sludge in the 20 MW bubbling fluidized bed boiler in Lidkoeping. Three combustion tests have been performed: - Ref - Reference test (normal fuel mix = 50% household waste/50% industrial waste). - F1 - Test 1 (75% normal fuel mix , 21% SLF and 4% sewage sludge) - F2 - Test 2 (77% normal fuel mix and 23% SLF) The fuel mix is specified as percentage of energy content. The tests lasted 3 days and during the last 24 hours corrosion and deposit probes were exposed inside the boiler. The surface temperatures of the corrosion probes were 280, 350 and 420 deg C in each test. At the same time as the probes were exposed the boiler operation was followed and samples of fuel, ash and flue gas were taken. The results clearly show that sewage sludge initially decreases the deposit and corrosion problems at SLF combustion. Lower amounts of deposits were measured and the deposits were less corrosive when 4% of sewage sludge was added to the fuel mix with normal waste and SLF (F1). Co-combustion of more than 20% SLF and wastes (F2) increase initially the amount of the deposits and the deposits were also initially more corrosive. Long-term consequences are not investigated in this project. The project has not shown a distinct explanation why sewage sludge gives these good effects. Several possible causes, as
International Nuclear Information System (INIS)
Saminadayar, L.
2001-01-01
20 years ago fractional charges were imagined to explain values of conductivity in some materials. Recent experiments have proved the existence of charges whose value is the third of the electron charge. This article presents the experimental facts that have led theorists to predict the existence of fractional charges from the motion of quasi-particles in a linear chain of poly-acetylene to the quantum Hall effect. According to the latest theories, fractional charges are neither bosons nor fermions but anyons, they are submitted to an exclusive principle that is less stringent than that for fermions. (A.C.)
Directory of Open Access Journals (Sweden)
Vučinić Aleksandra S.
2017-01-01
Full Text Available This paper presents the analysis of the quantity of plastic and waste printed circuit boards obtained after the mechanical treatment of electrical and electronic waste (E-waste in the Republic of Serbia, as well as the recycling of non-metallic fractions of waste printed circuit boards. The aim is to analyze the obtained recycled material and recommendation for possible application of recyclables. The data on the quantities and treatment of plastics and printed circuit boards obtained after the mechanical treatment of WEEE, were gained through questionnaires sent to the operators who treat this type of waste. The results of the questionnaire analysis showed that in 2014 the dismantling of E-waste isolated 1,870.95 t of plastic and 499.85 t of printed circuit boards. In the Republic of Serbia, E-waste recycling is performed exclusively by using mechanical methods. Mechanical methods consist of primary crushing and separation of the materials which have a utility value as secondary raw materials, from the components and materials that have hazardous properties. Respect to that, the recycling of printed circuit boards using some of the metallurgical processes with the aim of extracting copper, precious metals and non-metallic fraction is completely absent, and the circuit boards are exported as a whole. Given the number of printed circuit boards obtained by E-waste dismantling, and the fact that from an economic point of view, hydrometallurgical methods are very suitable technological solutions in the case of a smaller capacity, there is a possibility for establishing the facilities in the Republic of Serbia for the hydrometallurgical treatment that could be used for metals extraction, and non-metallic fractions, which also have their own value. Printed circuit boards granulate obtained after the mechanical pretreatment and the selective removal of metals by hydrometallurgical processes was used for the testing of the recycling potential
Hanley, Kevin W; Andrews, Ronnee; Bertke, Steven; Ashley, Kevin
2015-01-01
The National Institute for Occupational Safety and Health has conducted an occupational exposure assessment study of manganese (Mn) in welding fume of construction workers rebuilding tanks, piping, and process equipment at two oil refineries. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. Seventy-two worker-days were monitored for either total or respirable Mn during stick welding and associated activities both within and outside of confined spaces. The samples were analyzed using an experimental method to separate different Mn fractions by valence states based on selective chemical solubility. The full-shift total particulate Mn time-weighted average (TWA) breathing zone concentrations ranged from 0.013-29 for soluble Mn in a mild ammonium acetate solution; from 0.26-250 for Mn(0,2+) in acetic acid; from non-detectable (ND) - 350 for Mn(3+,4+) in hydroxylamine-hydrochloride; and from ND - 39 micrograms per cubic meter (μg/m(3)) for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all Mn fractions in total particulate TWA ranged from 0.52-470 μg/m(3). The range of respirable particulate Mn TWA concentrations were from 0.20-28 for soluble Mn; from 1.4-270 for Mn(0,2+); from 0.49-150 for Mn(3+,4+); from ND - 100 for insoluble Mn; and from 2.0-490 μg/m(3) for Mn (sum of fractions). For all jobs combined, total particulate TWA GM concentrations of the Mn(sum) were 99 (GSD = 3.35) and 8.7 (GSD = 3.54) μg/m(3) for workers inside and outside of confined spaces; respirable Mn also showed much higher levels for welders within confined spaces. Regardless of particle size and confined space work status, Mn(0,2+) fraction was the most abundant followed by Mn(3+,4+) fraction, typically >50% and ∼30-40% of Mn(sum), respectively. Eighteen welders' exposures exceeded the ACGIH Threshold Limit Values for total Mn (100 μg/m(3)) and 25 exceeded the recently adopted respirable
Hanley, Kevin W.; Andrews, Ronnee; Bertke, Steven; Ashley, Kevin
2015-01-01
The National Institute for Occupational Safety and Health (NIOSH) has conducted an occupational exposure assessment study of manganese (Mn) in welding fume of construction workers rebuilding tanks, piping, and process equipment at two oil refineries. The objective of this study was to evaluate exposures to different Mn fractions using a sequential extraction procedure. Seventy-two worker-days were monitored for either total or respirable Mn during stick welding and associated activities both within and outside of confined spaces. The samples were analyzed using an experimental method to separate different Mn fractions by valence states based on selective chemical solubility. The full-shift total particulate Mn time-weighted average (TWA) breathing zone concentrations ranged from 0.013 – 29 for soluble Mn in a mild ammonium acetate solution; from 0.26 – 250 for Mn0,2+ in acetic acid; from non-detectable (ND) – 350 for Mn3+,4+ in hydroxylamine-hydrochloride; and from ND – 39 micrograms per cubic meter (μg/m3) for insoluble Mn fractions in hydrochloric and nitric acid. The summation of all Mn fractions in total particulate TWA ranged from 0.52 to 470 μg/m3. The range of respirable particulate Mn TWA concentrations were from 0.20 – 28 for soluble Mn; from 1.4 – 270 for Mn0,2+; from 0.49 – 150 for Mn3+,4+; from ND – 100 for insoluble Mn; and from 2.0 – 490 μg/m3 for Mn (sum of fractions). For all jobs combined, total particulate TWA GM concentrations of the Mn(sum) were 99 (GSD=3.35) and 8.7 (GSD=3.54) μg/m3 for workers inside and outside of confined spaces; respirable Mn also showed much higher levels for welders within confined spaces. Regardless of particle size and confined space work status, Mn0,2+ fraction was the most abundant followed by Mn3+,4+ fraction, typically >50% and ~30-40% of Mn(sum), respectively. Eighteen welders’ exposures exceeded the ACGIH Threshold Limit Values for total Mn (100 μg/m3) and 25 exceeded the recently adopted
Marassi, Valentina; Casolari, Sonia; Roda, Barbara; Zattoni, Andrea; Reschiglian, Pierluigi; Panzavolta, Silvia; Tofail, Syed A M; Ortelli, Simona; Delpivo, Camilla; Blosi, Magda; Costa, Anna Luisa
2015-03-15
Due to the increased use of silver nanoparticles in industrial scale manufacturing, consumer products and nanomedicine reliable measurements of properties such as the size, shape and distribution of these nano particles in aqueous medium is critical. These properties indeed affect both functional properties and biological impacts especially in quantifying associated risks and identifying suitable risk-mediation strategies. The feasibility of on-line coupling of a fractionation technique such as hollow-fiber flow field flow fractionation (HF5) with a light scattering technique such as MALS (multi-angle light scattering) is investigated here for this purpose. Data obtained from such a fractionation technique and its combination thereof with MALS have been compared with those from more conventional but often complementary techniques e.g. transmission electron microscopy, dynamic light scattering, atomic absorption spectroscopy, and X-ray fluorescence. The combination of fractionation and multi angle light scattering techniques have been found to offer an ideal, hyphenated methodology for a simultaneous size-separation and characterization of silver nanoparticles. The hydrodynamic radii determined by fractionation techniques can be conveniently correlated to the mean average diameters determined by multi angle light scattering and reliable information on particle morphology in aqueous dispersion has been obtained. The ability to separate silver (Ag(+)) ions from silver nanoparticles (AgNPs) via membrane filtration during size analysis is an added advantage in obtaining quantitative insights to its risk potential. Most importantly, the methodology developed in this article can potentially be extended to similar characterization of metal-based nanoparticles when studying their functional effectiveness and hazard potential. Copyright © 2014 Elsevier B.V. All rights reserved.
Bhattacharyya, Sonalee; Namakshi, Nama; Zunker, Christina; Warshauer, Hiroko K.; Warshauer, Max
2016-01-01
Making math more engaging for students is a challenge that every teacher faces on a daily basis. These authors write that they are constantly searching for rich problem-solving tasks that cover the necessary content, develop critical-thinking skills, and engage student interest. The Mystery Fraction activity provided here focuses on a key number…
Adaptive control and synchronization of a fractional-order chaotic ...
Indian Academy of Sciences (India)
tem based on the stability theory of fractional-order dynamic systems. The presented schemes, which contain only a single-state variable, are simple and flexible. Numerical simulations are used to demonstrate the feasibility of the presented methods. Keywords. Fractional order; adaptive scheme; control; synchronization.
Trace metal speciation and bioavailability in anaerobic digestion: A review.
Thanh, Pham Minh; Ketheesan, Balachandran; Yan, Zhou; Stuckey, David
2016-01-01
Trace metals are essential for the growth of anaerobic microorganisms, however, in practice they are often added to anaerobic digesters in excessive amounts, which can lead to inhibition. The concept of bioavailability of metals in anaerobic digestion has been poorly understood in the past, and a lack of deep understanding of the relationship between trace metal speciation and bioavailability can result in ineffective metal dosing strategies for anaerobic digesters. Sequential extraction schemes are useful for fractionating trace metals into their different forms, and metal sulfides can serve as a store and source for trace metals during anaerobic digestion, while natural/synthetic chelating agents (soluble microbial products-SMPs, extracellular polysaccharides-EPS, and EDTA/NTA) are capable of controlling trace metal bioavailability. Nevertheless, more work is needed to: investigate the speciation and bioavailability of Ca, Mg, Mn, W, and Se; compare the bioavailability of different forms of trace metals e.g. carbonates, sulfides, phosphates to different anaerobic trophic groups; determine what factors influence metal sulfide dissolution; investigate whether chelating agents can increase trace metal bioavailability; develop and adapt specialized analytical techniques, and; determine how trace metal dynamics change in an anaerobic membrane bioreactor (AnMBR). Copyright © 2015 Elsevier Inc. All rights reserved.
Wang, Baoyong; Zheng, Chunfang; Sankoff, David
2011-01-01
Abstract Background Paralog reduction, the loss of duplicate genes after whole genome duplication (WGD) is a pervasive process. Whether this loss proceeds gene by gene or through deletion of multi-gene DNA segments is controversial, as is the question of fractionation bias, namely whether one homeologous chromosome is more vulnerable to gene deletion than the other. Results As a null hypothesis, we first assume deletion events, on one homeolog only, excise a geometrically distributed number o...
Kaczala, Fabio; Orupõld, Kaja; Augustsson, Anna; Burlakovs, Juris; Hogland, Marika; Bhatnagar, Amit; Hogland, William
2017-11-01
The fractionation of metals in the fine fraction (circular economy and recovery of such valuables back into the economy. To conclude, not only the total concentration of metals but also a better understanding of fractionation and in which form metals are bound is very important to bring information on how to manage the fine fraction from excavated waste both in terms of environmental impacts and also recovery of such valuables in the economy.
International Nuclear Information System (INIS)
Kartal, Senol; Aydin, Zeki; Tokalioglu, Serife
2006-01-01
The concentrations of metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in street sediment samples were determined by flame atomic absorption spectrometry (FAAS) using the modified BCR (the European Community Bureau of Reference) sequential extraction procedure. According to the BCR protocol for extracting the metals from the relevant target phases, 1.0 g of specimen of the sample was treated with 0.11 M acetic acid (exchangeable and bound to carbonates), 0.5 M hydroxylamine hydrochloride (bound to iron- and manganese-oxides), and 8.8 M hydrogen peroxide plus 1 M ammonium acetate (bound to sulphides and organics), sequentially. The residue was treated with aqua regia solution for recovery studies, although this step is not part of the BCR procedure. The mobility sequence based on the sum of the BCR sequential extraction stages was: Cd ∼ Zn (∼90%) > Pb (∼84%) > Cu (∼75%) > Mn (∼70%) > Co (∼57%) > Ni (∼43%) > Cr (∼40%) > Fe (∼17%). Enrichment factors as the criteria for examining the impact of the anthropogenic emission sources of heavy metals were calculated, and it was observed that the highest enriched elements were Cd, Pb, and Zn in the dust samples, average 190, 111, and 20, respectively. Correlation analysis (CA) and principal component analysis (PCA) were applied to the data matrix to evaluate the analytical results and to identify the possible pollution sources of metals. PCA revealed that the sampling area was mainly influenced from three pollution sources, namely; traffic, industrial, and natural sources. The results show that chemical sequential extraction is a precious operational tool. Validation of the analytical results was checked by both recovery studies and analysis of the standard reference material (NIST SRM 2711 Montana Soil)
Czech Academy of Sciences Publication Activity Database
Vojtěšek, Martin; Mikuška, Pavel; Večeřa, Zbyněk; Křůmal, Kamil
2012-01-01
Roč. 92, č. 4 (2012), s. 432-449 ISSN 0306-7319 R&D Projects: GA MŽP SP/1A3/148/08; GA MŽP SP/1B7/189/07; GA MŽP SP/1A3/55/08 Institutional research plan: CEZ:AV0Z40310501 Keywords : atmospheric aerosols * metals * continuous aerosol collector Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.240, year: 2012
Hinkley, T.K.; Seeley, J.L.; Tatsumoto, M.
1988-01-01
Three distinct types of solid material are associated with each sample of the hydrothermal fluid that was collected from the vents of the Southern Juan de Fuca Ridge. The solid materials appear to be representative of deposits on ocean floors near mid-ocean ridges, and interpretation of the chemistry of the hydrothermal solutions requires understanding of them. Sr isotopic evidence indicates that at least two and probably all three of these solid materials were removed from the solution with which they are associated, by precipitation or adsorption. This occurred after the "pure" hydrothermal fluid was diluted and thoroughly mixed with ambient seawater. The three types of solid materials, are, respectively, a coarse Zn- and Fe-rich material with small amounts of Na and Ca; a finer material also rich in Zn and Fe, but with alkali and alkaline-earth metals; and a scum composed of Ba or Zn, with either considerable Fe or Si, and Sr. Mineral identification is uncertain because of uncertain anion composition. Only in the cases of Ba and Zn were metal masses greater in solid materials than in the associated fluids. For all other metals measured, masses in fluids dwarf those in solids. The fluids themselves contain greater concentrations of all metals measured, except Mg, than seawater. We discuss in detail the relative merits of two methods of determining the mixing proportions of "pure" hydrothermal solution and seawater in the fluids, one based on Sr isotopes, and another previously used method based on Mg concentrations. Comparison of solute concentrations in the several samples shows that degree of dilution of "pure" hydrothermal solutions by seawater, and amounts of original solutes that were removed from it as solid materials, are not related. There is no clear evidence that appreciable amounts of solid materials were not conserved (lost) either during or prior to sample collection. ?? 1988.
de Bont, Chris
2018-01-01
This booklet was written to share research results with farmers and practitioners in Tanzania. It gives a summary of the empirical material collected during three months of field work in the Mawala irrigation scheme (Kilimanjaro Region), and includes maps, tables and photos. It describes the history of the irrigation scheme, as well current irrigation and farming practices. It especially focuses on the different kinds of infrastructural improvement in the scheme (by farmers and the government...
International Nuclear Information System (INIS)
McElmurry, Shawn P.; Long, David T.; Voice, Thomas C.
2010-01-01
Trace metal cycling in natural waters is highly influenced by the amount and type of dissolved organic C (DOC). Although determining individual species of DOC is unrealistic, there has been success in classifying DOC by determining operationally defined fractions. However, current fractionation schemes do not allow for the simultaneous quantification of associated trace metals. Using operational classifications, a scheme was developed to fractionate DOC based on a set of seven solid-phase extraction (SPE) cartridges. The cartridges isolated fractions based on a range of specific mechanisms thought to be responsible for DOC aggregation in solution, as well as molecular weight. The method was evaluated to determine if it can identify differences in DOC characteristics, including differences in Cu-DOC complexation. Results are that: (1) cartridge blanks were low for both DOC and Cu, (2) differences are observed in the distribution of DOC amongst the fractions from various sources that are consistent with what is known about the DOC materials and the mechanisms operative for each cartridge, (3) when present as a free cation, Cu was not retained by non-cationic cartridges allowing the method to be used to assess Cu binding, (4) the capability of the method to provide quantitative assessment of Cu-DOC complexation was demonstrated for a variety of DOC standards, (5) Cu was found to preferentially bind with high molecular weight fractions of DOC, and (6) estimated partitioning coefficients and conditional binding constants for Cu were similar to those reported elsewhere. The method developed describes DOC characteristics based on specific bonding mechanisms (hydrogen, donor-acceptor, London dispersion, and ionic bonding) while simultaneously quantifying Cu-DOC complexation. The method provides researchers a means of describing not only the extent of DOC complexation but also how that complex will be behave in natural waters.
DEFF Research Database (Denmark)
Juhl, Hans Jørn; Stacey, Julia
2001-01-01
to carry out a campaign targeted at this segment. The awareness percentage is already 92 % and 67% of the respondents believe they know the meaning of the scheme. But it stands to reason to study whether the respondents actually know what the labelling scheme stands for or if they just think they do...
CSIR Research Space (South Africa)
Debba, Pravesh
2009-07-01
Full Text Available ) showed that heavy metal contamination in soils can be quantified using reflectance spectroscopy. Debba (CSIR) Spatial sampling scheme NMMU 2009 4 / 57 Background and Research Question Remote sensing provides an indirect tool for surface...) Spatial sampling scheme NMMU 2009 33 / 57 Methodology Modeling of heavy metal associations Concentrations of several metals in soils can be estimated using reflectance spectroscopy. Model heavy metals association reflecting scavenging of metals...
Directory of Open Access Journals (Sweden)
R. Sitharthan
2016-09-01
Full Text Available This paper aims at modelling an electronically coupled distributed energy resource with an adaptive protection scheme. The electronically coupled distributed energy resource is a microgrid framework formed by coupling the renewable energy source electronically. Further, the proposed adaptive protection scheme provides a suitable protection to the microgrid for various fault conditions irrespective of the operating mode of the microgrid: namely, grid connected mode and islanded mode. The outstanding aspect of the developed adaptive protection scheme is that it monitors the microgrid and instantly updates relay fault current according to the variations that occur in the system. The proposed adaptive protection scheme also employs auto reclosures, through which the proposed adaptive protection scheme recovers faster from the fault and thereby increases the consistency of the microgrid. The effectiveness of the proposed adaptive protection is studied through the time domain simulations carried out in the PSCAD⧹EMTDC software environment.
Synchronization of two coupled fractional-order chaotic oscillators
International Nuclear Information System (INIS)
Gao Xin; Yu, Juebang
2005-01-01
The dynamics of fractional-order systems have attracted increasing attentions in recent years. In this paper, the synchronization of two coupled nonlinear fractional order chaotic oscillators is numerically demonstrated using the master-slave synchronization scheme. It is shown that fractional-order chaotic oscillators can be synchronized with appropriate coupling strength
DYNAMICS OF FRACTIONAL ORDER CHAOTIC SYSTEM
Directory of Open Access Journals (Sweden)
M. Jana
2017-02-01
Full Text Available This paper deals with the dynamics of chaos and synchronization for fractional order chaotic system. For fractional order derivative Captuo definition is used here and numerical simulations are done using Predictor-Correctors scheme by Diethlm based on the Adams-Baseforth-Moulton algorithm. Stability analysis is discussed here for non linear fractional order chaotic system and synchronization is achieved between two non identical fractional order chaotic systems: Finance chaotic system(driving systemand Lorenz system(response systemvia active control.Numerical simulations are performed to show the effectiveness of these approaches.
Threshold Signature Schemes Application
Directory of Open Access Journals (Sweden)
Anastasiya Victorovna Beresneva
2015-10-01
Full Text Available This work is devoted to an investigation of threshold signature schemes. The systematization of the threshold signature schemes was done, cryptographic constructions based on interpolation Lagrange polynomial, elliptic curves and bilinear pairings were examined. Different methods of generation and verification of threshold signatures were explored, the availability of practical usage of threshold schemes in mobile agents, Internet banking and e-currency was shown. The topics of further investigation were given and it could reduce a level of counterfeit electronic documents signed by a group of users.
International Nuclear Information System (INIS)
Turner, R.E.
1984-01-01
A search was made for fractional charges of the form Z plus two-thirds e, where Z is an integer. It was assumed that the charges exist in natural form bound with other fractional charges in neutral molecules. It was further assumed that these neutral molecules are present in air. Two concentration schemes were employed. One sample was derived from the waste gases from a xenon distillation plant. This assumes that high mass, low vapor pressure components of air are concentrated along with the xenon. The second sample involved ionizing air, allowing a brief recombination period, and then collecting residual ions on the surface of titanium discs. Both samples were analyzed at the University of Rochester in a system using a tandem Van de Graff to accelerate particles through an essentially electrostatic beam handling system. The detector system employed both a Time of Flight and an energy-sensitive gas ionization detector. In the most sensitive mode of analysis, a gas absorber was inserted in the beam path to block the intense background. The presence of an absorber limited the search to highly penetrating particles. Effectively, this limited the search to particles with low Z and masses greater than roughly fifty GeV. The final sensitivities attained were on the order of 1 x 10 -20 for the ionized air sample and 1 x 10 -21 for the gas sample. A discussion of the caveats that could reduce the actual level of sensitivity is included
Energy Technology Data Exchange (ETDEWEB)
Willcock, J J; Lumsdaine, A; Quinlan, D J
2008-08-19
Tabled execution is a generalization of memorization developed by the logic programming community. It not only saves results from tabled predicates, but also stores the set of currently active calls to them; tabled execution can thus provide meaningful semantics for programs that seemingly contain infinite recursions with the same arguments. In logic programming, tabled execution is used for many purposes, both for improving the efficiency of programs, and making tasks simpler and more direct to express than with normal logic programs. However, tabled execution is only infrequently applied in mainstream functional languages such as Scheme. We demonstrate an elegant implementation of tabled execution in Scheme, using a mix of continuation-passing style and mutable data. We also show the use of tabled execution in Scheme for a problem in formal language and automata theory, demonstrating that tabled execution can be a valuable tool for Scheme users.
DEFF Research Database (Denmark)
Hansen, Elo Harald; Wang, Jianhua
2002-01-01
Various preconditioning procedures encomprising appropriate separation/preconcentration schemes in order to obtain optimal sensitivity and selectivity characteristics when using electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICPMS...
International Nuclear Information System (INIS)
2002-04-01
This scheme defines the objectives relative to the renewable energies and the rational use of the energy in the framework of the national energy policy. It evaluates the needs and the potentialities of the regions and preconizes the actions between the government and the territorial organizations. The document is presented in four parts: the situation, the stakes and forecasts; the possible actions for new measures; the scheme management and the regional contributions analysis. (A.L.B.)
Indian Academy of Sciences (India)
substituent effects in the head-to-tail double insertion reactions observed ... an internal standard. The yield of diphenyl carbodii- mide was further verified by isolating it as diphenyl urea after hydrolysis. The organic fraction obtained in the catalytic metathesis .... insertion of PhNCO into metal alkoxide 1a to generate. Table 1.
Energy Technology Data Exchange (ETDEWEB)
Placidi, M.; Jung, J. -Y.; Ratti, A.; Sun, C.
2014-07-25
This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.
Energy Technology Data Exchange (ETDEWEB)
Placidi, M.; Jung, J.-Y.; Ratti, A.; Sun, C., E-mail: csun@lbl.gov
2014-12-21
This paper describes beam distribution schemes adopting a novel implementation based on low amplitude vertical deflections combined with horizontal ones generated by Lambertson-type septum magnets. This scheme offers substantial compactness in the longitudinal layouts of the beam lines and increased flexibility for beam delivery of multiple beam lines on a shot-to-shot basis. Fast kickers (FK) or transverse electric field RF Deflectors (RFD) provide the low amplitude deflections. Initially proposed at the Stanford Linear Accelerator Center (SLAC) as tools for beam diagnostics and more recently adopted for multiline beam pattern schemes, RFDs offer repetition capabilities and a likely better amplitude reproducibility when compared to FKs, which, in turn, offer more modest financial involvements both in construction and operation. Both solutions represent an ideal approach for the design of compact beam distribution systems resulting in space and cost savings while preserving flexibility and beam quality.
Radionuclide fractionation in organic matter-enriched soils
International Nuclear Information System (INIS)
Rigol, A.; Vidal, M.; Rauret, G.
1995-01-01
Sequential extraction scheme was proposed in order to obtain radionuclide distribution and predict its mobility in soil-plant system. This scheme is useful to be able to explain changes of the radionuclide behaviour over time, i.e., decrease in exchangeable-available fraction and increase in fixed-mineral-fraction. A sequential extraction scheme which considers the different interactions between organic matter in radionuclide may give information about the role of organic matter in radionuclide retention. Such scheme has been designed and it defines a series of fractions from the sequential use of different extractant reagents. The extraction scheme allows to estimate, in a operational way, the fraction of radionuclide associated with exchangeable sites (Fraction 1), with humic and fulvic acids (Fraction 2 and 3), the amount of radionuclide related to passive organic matter like humine, non-humic substances or mineral organic matter (Fraction 4) and the radionuclide highly fixed to soil mineral matter (residual fraction). The results allowing to ascertain which are sites responsible for radiocesium retention
Distribution of different fractions of Iron, Zinc, Chromium, lead and ...
African Journals Online (AJOL)
The mobility factor values of the metals were moderately high with the abundance trend of Pb > Ni > Cr > Fe > Zn. The generally low levels of the metals in the residual fraction coupled with the mobility factor trend suggest potential risk for the metals. Keywords: Soil pollution, speciation, petrol filling stations, heavy metals, ...
Energy Technology Data Exchange (ETDEWEB)
Meyer, B.; Starke, A. [TU Bergakademie Freiberg (Germany). Inst. IEC
1998-09-01
Co-combustion plants, in which fuel is partly substituted by waste materials, are subject to the 17th BImSchV (Nuisance Control Ordinance) provided that the thermal fraction of 25% is not exceeded. Emission limits are calculated proportionately on the basis of limiting values for emissions from coal power stations (13th BImSchV) and waste incinerators (17th BImSchV). Compared to coal, waste has higher concentrations of heavy metals and halogens, which results in enhanced emissions of heavy metal compounds and chlorides with the flue gas and gasification gas. Plant operators intending to opt for co-combustion must check if the existing flue gas purification system is efficient enough to meet the specifications of the 17th BImSchV. In general, thermodynamic modelling is the most common method of evaluation and optimisation for high-temperature processes of this kind. (orig./SR) [Deutsch] Da bei der Mitverbrennung ein Teil des Brennstoffes durch den Reststoff substituiert wird, unterliegen diese Anlagen der Anteilsregelung nach 17. BImSchV, sofern ein thermischer Anteil von 25% nicht ueberschritten wird. Emissionsgrenzwerte werden anteilig aus den z.B. fuer Kohlekraftwerke gueltigen Grenzwerten nach TA Luft oder 13. BImSchV und denen fuer Abfaelle u.ae. nach 17 BImSchV ermittelt. Der hier betrachtete Reststoff Muell beinhaltet im Vergleich zur Kohle hohe Konzentrationen an Schwermetallen und Halogenen. Dies laesst eine erhoehte Emission von Schwermetallverbindungen und Chloriden mit dem Rauchgas bzw. Vergasungsgas erwarten. Es muss in jedem Fall ueberprueft werden, ob die vorhandene Rauchgasreinigung ausreicht, wenn bei der Mitverbrennung/-vergasung die Emissionsgrenzwerte der 17. BImSchV zur Anwendung kommen. Als Bewertungs- und Optimierungsmethode fuer derartige Hochtemperaturprozesse setzt sich die thermodynamische Modellierung zunehmend durch. (orig./SR)
On the Froehlich decomposition and the condensate fraction in He II
International Nuclear Information System (INIS)
Ghassib, H.B.; Sridhar, R.
1983-09-01
The method of extracting the Bose-Einstein condensate fraction in He II within the Froehlich decomposition scheme is revisited. A new simple formula for determining this fraction is derived. Possible experimental and theoretical implications are discussed. (author)
Solutions of fractional diffusion equations by variation of parameters method
Directory of Open Access Journals (Sweden)
Mohyud-Din Syed Tauseef
2015-01-01
Full Text Available This article is devoted to establish a novel analytical solution scheme for the fractional diffusion equations. Caputo’s formulation followed by the variation of parameters method has been employed to obtain the analytical solutions. Following the derived analytical scheme, solution of the fractional diffusion equation for several initial functions has been obtained. Graphs are plotted to see the physical behavior of obtained solutions.
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 2. Electronic Commerce - Payment Schemes. V Rajaraman. Series Article Volume 6 Issue 2 February 2001 pp 6-13. Fulltext. Click here to view fulltext PDF. Permanent link: https://www.ias.ac.in/article/fulltext/reso/006/02/0006-0013 ...
Link Monotonic Allocation Schemes
Slikker, M.
1999-01-01
A network is a graph where the nodes represent players and the links represent bilateral interaction between the players. A reward game assigns a value to every network on a fixed set of players. An allocation scheme specifies how to distribute the worth of every network among the players. This
Alternative health insurance schemes
DEFF Research Database (Denmark)
Keiding, Hans; Hansen, Bodil O.
2002-01-01
In this paper, we present a simple model of health insurance with asymmetric information, where we compare two alternative ways of organizing the insurance market. Either as a competitive insurance market, where some risks remain uninsured, or as a compulsory scheme, where however, the level...... competitive insurance; this situation turns out to be at least as good as either of the alternatives...
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 2. Electronic Commerce - Payment Schemes. V Rajaraman. Series Article Volume 6 Issue 2 February 2001 pp 6-13 ... Author Affiliations. V Rajaraman1. IBM Professor of Information Technology JNCASR Bangalore 560 064, India.
DEFF Research Database (Denmark)
Pötz, Katharina Anna; Haas, Rainer; Balzarova, Michaela
2013-01-01
of schemes that can be categorized on focus areas, scales, mechanisms, origins, types and commitment levels. Research limitations/implications – The findings contribute to conceptual and empirical research on existing models to compare and analyse CSR standards. Sampling technique and depth of analysis limit...
Simple monotonic interpolation scheme
International Nuclear Information System (INIS)
Greene, N.M.
1980-01-01
A procedure for presenting tabular data, such as are contained in the ENDF/B files, that is simpler, more general, and potentially much more compact than the present schemes used with ENDF/B is presented. The method has been successfully used for Bondarenko interpolation in a module of the AMPX system. 1 figure, 1 table
Fractional Vector Calculus and Fractional Special Function
Li, Ming-Fan; Ren, Ji-Rong; Zhu, Tao
2010-01-01
Fractional vector calculus is discussed in the spherical coordinate framework. A variation of the Legendre equation and fractional Bessel equation are solved by series expansion and numerically. Finally, we generalize the hypergeometric functions.
Directory of Open Access Journals (Sweden)
Évio Eduardo Chaves de Melo
2006-12-01
. The study aimed to compare the performance of natural organic acids (gallic, citric, and oxalic to synthetic chelates/acids EDTA, DTPA, and NTA for induced phytoextraction of Pb, Cu and Zn by corn (Zea mays and velvetbean (Stizolobium aterrimum. Soil samples were contaminated to concentrations: 500 (Pb, 300 (Zn, and 200 (Cu mg kg-1, and cultivated for 35 days. The chelators were applied at 10 mmol kg-1 seven days before harvest. Soil samples were submitted to chemical extraction by CaCl2 and chemical fractionation. Heavy metal concentrations in the soil solution were also determined. EDTA, DTPA, and NTA were effective at solubilizing the heavy metals. Citric acid was efficient to solubilize metals in the first 24 h after application. The metal distribution across soil fractions followed the sequence: Pb: MO > OxFeA > Tr > OxFeC; Cu: MO > Tr > OxFeC > OxFeA; and Zn: MO > Tr > OxFeC > OxFeA. In general, synthetic chelators increased the exchangeable contents of Pb and Cu and decreased Pb, Cu, and Zn contents in the amorphous and crystalline iron oxides fractions. The extractant CaCl2 0.01 mol L-1 can be used to predict Pb, Cu, and Zn concentrations in soil solution.
Sarapulova, Angelina; Dampilova, Bayarma V; Bardamova, Irina; Doroshkevich, Svetlana G; Smirnova, Olga
2017-04-01
Mining of Dzhida ore deposits in Russia has caused the formation of a large tailings dam with technogenic sands and contamination of nearby district soils. Geochemical fractions of technogenic sands were divided by a sequential extraction procedure. The sampling points with maximum concentration of Pb, Cu, and Zn were selected for investigation of heavy metal mobility. Two previously described methods of heavy metal fractionation using selective extraction were applied: a procedure developed by the Community Bureau of Reference of the Commission of the European Communities (BCR procedure) and Tessier's fractionation scheme. Despite some differences in Pb extractions, the two procedures describe equally well the distribution of heavy metals on geochemical fractions. BCR procedure was chosen as a fast method of heavy metal mobile form estimation. For considered mining object, it is revealed that there are different characters of heavy metal mobility sequence in the soils Zn > Cu > Pb and technogenic sands Pb > Zn > Cu.
On Converting Secret Sharing Scheme to Visual Secret Sharing Scheme
Directory of Open Access Journals (Sweden)
Wang Daoshun
2010-01-01
Full Text Available Abstract Traditional Secret Sharing (SS schemes reconstruct secret exactly the same as the original one but involve complex computation. Visual Secret Sharing (VSS schemes decode the secret without computation, but each share is m times as big as the original and the quality of the reconstructed secret image is reduced. Probabilistic visual secret sharing (Prob.VSS schemes for a binary image use only one subpixel to share the secret image; however the probability of white pixels in a white area is higher than that in a black area in the reconstructed secret image. SS schemes, VSS schemes, and Prob. VSS schemes have various construction methods and advantages. This paper first presents an approach to convert (transform a -SS scheme to a -VSS scheme for greyscale images. The generation of the shadow images (shares is based on Boolean XOR operation. The secret image can be reconstructed directly by performing Boolean OR operation, as in most conventional VSS schemes. Its pixel expansion is significantly smaller than that of VSS schemes. The quality of the reconstructed images, measured by average contrast, is the same as VSS schemes. Then a novel matrix-concatenation approach is used to extend the greyscale -SS scheme to a more general case of greyscale -VSS scheme.
Energy Technology Data Exchange (ETDEWEB)
Lu, J.C.S.; Eichenberger, B.; Knezevic, M.; Chen, K.Y.
1978-05-01
A detailed analysis of contaminants in influents and effluents from two confined dredged material disposal areas is presented. The sites are located at Pinto Island, Mobile Bay, Alabama, and Grassy Island, Detroit, Michigan. The samples were separated into 0.05-Mm, 0.45-Mm, and 8.0-Mm, fractions. The total sample and filtrate were analyzed for metals, nutrients, total carbon, organic carbon, chlorinated hydrocarbons, oil and grease, sulfide, and solids content. The total solids were subjected to a geochemical partitioning scheme to determine changes of metal solid phases during confined area disposal. The oil and grease fractions in the samples were analyzed for trace metals. A 48-hr settling test was performed to quantify the migration of soil and grease and chlorinated hydrocarbons during resedimentation of dredged material within a confined area. A statistical analysis of the data was performed to determine the significance of variance in terms of pollutant loading between influent and background water; influent and effluent in terms of removal efficiency; and effluent and background water in terms of potential water quality impact. Tests for significance at the 95 and 99 % confidence levels are presented. The results show that, in general, the removal efficiency of total trace metals was very similar to the total solids removal. These results are in agreement with the analytical data which show that approximately 99% of the total trace metals was associated with the solid settleable phase (> 8-Mm).
A subgrid parameterization scheme for precipitation
Directory of Open Access Journals (Sweden)
S. Turner
2012-04-01
Full Text Available With increasing computing power, the horizontal resolution of numerical weather prediction (NWP models is improving and today reaches 1 to 5 km. Nevertheless, clouds and precipitation formation are still subgrid scale processes for most cloud types, such as cumulus and stratocumulus. Subgrid scale parameterizations for water vapor condensation have been in use for many years and are based on a prescribed probability density function (PDF of relative humidity spatial variability within the model grid box, thus providing a diagnosis of the cloud fraction. A similar scheme is developed and tested here. It is based on a prescribed PDF of cloud water variability and a threshold value of liquid water content for droplet collection to derive a rain fraction within the model grid. Precipitation of rainwater raises additional concerns relative to the overlap of cloud and rain fractions, however. The scheme is developed following an analysis of data collected during field campaigns in stratocumulus (DYCOMS-II and fair weather cumulus (RICO and tested in a 1-D framework against large eddy simulations of these observed cases. The new parameterization is then implemented in a 3-D NWP model with a horizontal resolution of 2.5 km to simulate real cases of precipitating cloud systems over France.
Energy Technology Data Exchange (ETDEWEB)
Elliott, C.J.; Fisher, H.; Pepin, J. [Los Alamos National Lab., NM (United States); Gillmann, R. [Federal Highway Administration, Washington, DC (United States)
1996-07-01
Traffic classification techniques were evaluated using data from a 1993 investigation of the traffic flow patterns on I-20 in Georgia. First we improved the data by sifting through the data base, checking against the original video for questionable events and removing and/or repairing questionable events. We used this data base to critique the performance quantitatively of a classification method known as Scheme F. As a context for improving the approach, we show in this paper that scheme F can be represented as a McCullogh-Pitts neural network, oar as an equivalent decomposition of the plane. We found that Scheme F, among other things, severely misrepresents the number of vehicles in Class 3 by labeling them as Class 2. After discussing the basic classification problem in terms of what is measured, and what is the desired prediction goal, we set forth desirable characteristics of the classification scheme and describe a recurrent neural network system that partitions the high dimensional space up into bins for each axle separation. the collection of bin numbers, one for each of the axle separations, specifies a region in the axle space called a hyper-bin. All the vehicles counted that have the same set of in numbers are in the same hyper-bin. The probability of the occurrence of a particular class in that hyper- bin is the relative frequency with which that class occurs in that set of bin numbers. This type of algorithm produces classification results that are much more balanced and uniform with respect to Classes 2 and 3 and Class 10. In particular, the cancellation of errors of classification that occurs is for many applications the ideal classification scenario. The neural network results are presented in the form of a primary classification network and a reclassification network, the performance matrices for which are presented.
Scalable Nonlinear Compact Schemes
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Debojyoti [Argonne National Lab. (ANL), Argonne, IL (United States); Constantinescu, Emil M. [Univ. of Chicago, IL (United States); Brown, Jed [Univ. of Colorado, Boulder, CO (United States)
2014-04-01
In this work, we focus on compact schemes resulting in tridiagonal systems of equations, specifically the fifth-order CRWENO scheme. We propose a scalable implementation of the nonlinear compact schemes by implementing a parallel tridiagonal solver based on the partitioning/substructuring approach. We use an iterative solver for the reduced system of equations; however, we solve this system to machine zero accuracy to ensure that no parallelization errors are introduced. It is possible to achieve machine-zero convergence with few iterations because of the diagonal dominance of the system. The number of iterations is specified a priori instead of a norm-based exit criterion, and collective communications are avoided. The overall algorithm thus involves only point-to-point communication between neighboring processors. Our implementation of the tridiagonal solver differs from and avoids the drawbacks of past efforts in the following ways: it introduces no parallelization-related approximations (multiprocessor solutions are exactly identical to uniprocessor ones), it involves minimal communication, the mathematical complexity is similar to that of the Thomas algorithm on a single processor, and it does not require any communication and computation scheduling.
Quantum identification schemes with entanglements
International Nuclear Information System (INIS)
Mihara, Takashi
2002-01-01
We need secure identification schemes because many situations exist in which a person must be identified. In this paper, we propose three quantum identification schemes with entanglements. First, we propose a quantum one-time pad password scheme. In this scheme, entanglements play the role of a one-time pad password. Next, we propose a quantum identification scheme that requires a trusted authority. Finally, we propose a quantum message authentication scheme that is constructed by combining a different quantum cryptosystem with an ordinary authentication tag
The synchronisation of fractional-order hyperchaos compound system
Noghredani, Naeimadeen; Riahi, Aminreza; Pariz, Naser; Karimpour, Ali
2018-02-01
This paper presents a new compound synchronisation scheme among four hyperchaotic memristor system with incommensurate fractional-order derivatives. First a new controller was designed based on adaptive technique to minimise the errors and guarantee compound synchronisation of four fractional-order memristor chaotic systems. According to the suitability of compound synchronisation as a reliable solution for secure communication, we then examined the application of the proposed adaptive compound synchronisation scheme in the presence of noise for secure communication. In addition, the unpredictability and complexity of the drive systems enhance the security of secure communication. The corresponding theoretical analysis and results of simulation validated the effectiveness of the proposed synchronisation scheme using MATLAB.
The synchronisation of fractional-order hyperchaos compound system
Indian Academy of Sciences (India)
This paper presents a new compound synchronisation scheme among four hyperchaotic memristor system with incommensurate fractional-order derivatives. First a new controller was designed based on adaptivetechnique to minimise the errors and guarantee compound synchronisation of four fractional-order memristor ...
Yasas, F M
1977-01-01
In response to a United Nations resolution, the Mobile Training Scheme (MTS) was set up to provide training to the trainers of national cadres engaged in frontline and supervisory tasks in social welfare and rural development. The training is innovative in its being based on an analysis of field realities. The MTS team consisted of a leader, an expert on teaching methods and materials, and an expert on action research and evaluation. The country's trainers from different departments were sent to villages to work for a short period and to report their problems in fulfilling their roles. From these grass roots experiences, they made an analysis of the job, determining what knowledge, attitude and skills it required. Analysis of daily incidents and problems were used to produce indigenous teaching materials drawn from actual field practice. How to consider the problems encountered through government structures for policy making and decisions was also learned. Tasks of the students were to identify the skills needed for role performance by job analysis, daily diaries and project histories; to analyze the particular community by village profiles; to produce indigenous teaching materials; and to practice the role skills by actual role performance. The MTS scheme was tried in Nepal in 1974-75; 3 training programs trained 25 trainers and 51 frontline workers; indigenous teaching materials were created; technical papers written; and consultations were provided. In Afghanistan the scheme was used in 1975-76; 45 participants completed the training; seminars were held; and an ongoing Council was created. It is hoped that the training program will be expanded to other countries.
Bonus Schemes and Trading Activity
Pikulina, E.S.; Renneboog, L.D.R.; Ter Horst, J.R.; Tobler, P.N.
2013-01-01
Abstract: Little is known about how different bonus schemes affect traders’ propensity to trade and which bonus schemes improve traders’ performance. We study the effects of linear versus threshold (convex) bonus schemes on traders’ behavior. Traders purchase and sell shares in an experimental stock
International Nuclear Information System (INIS)
Grashilin, V.A.; Karyshev, Yu.Ya.
1982-01-01
A 6-cycle scheme of step motor is described. The block-diagram and the basic circuit of the step motor control are presented. The step motor control comprises a pulse shaper, electronic commutator and power amplifiers. The step motor supply from 6-cycle electronic commutator provides for higher reliability and accuracy than from 3-cycle commutator. The control of step motor work is realised by the program given by the external source of control signals. Time-dependent diagrams for step motor control are presented. The specifications of the step-motor is given
Initialized Fractional Calculus
Lorenzo, Carl F.; Hartley, Tom T.
2000-01-01
This paper demonstrates the need for a nonconstant initialization for the fractional calculus and establishes a basic definition set for the initialized fractional differintegral. This definition set allows the formalization of an initialized fractional calculus. Two basis calculi are considered; the Riemann-Liouville and the Grunwald fractional calculi. Two forms of initialization, terminal and side are developed.
Synchronization of fractional fuzzy cellular neural networks with interactions
Ma, Weiyuan; Li, Changpin; Wu, Yujiang; Wu, Yongqing
2017-10-01
In this paper, we introduce fuzzy theory into the fractional cellular neural networks to dynamically enhance the coupling strength and propose a fractional fuzzy neural network model with interactions. Using the Lyapunov principle of fractional differential equations, we design the adaptive control schemes to realize the synchronization and obtain the synchronization criteria. Finally, we provide some numerical examples to show the effectiveness of our obtained results.
Sabzikar, Farzad; Meerschaert, Mark M.; Chen, Jinghua
2015-07-01
Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.
Energy Technology Data Exchange (ETDEWEB)
Sabzikar, Farzad, E-mail: sabzika2@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Meerschaert, Mark M., E-mail: mcubed@stt.msu.edu [Department of Statistics and Probability, Michigan State University, East Lansing, MI 48823 (United States); Chen, Jinghua, E-mail: cjhdzdz@163.com [School of Sciences, Jimei University, Xiamen, Fujian, 361021 (China)
2015-07-15
Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered fractional difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.
Packet reversed packet combining scheme
International Nuclear Information System (INIS)
Bhunia, C.T.
2006-07-01
The packet combining scheme is a well defined simple error correction scheme with erroneous copies at the receiver. It offers higher throughput combined with ARQ protocols in networks than that of basic ARQ protocols. But packet combining scheme fails to correct errors when the errors occur in the same bit locations of two erroneous copies. In the present work, we propose a scheme that will correct error if the errors occur at the same bit location of the erroneous copies. The proposed scheme when combined with ARQ protocol will offer higher throughput. (author)
Hypo fractionated radiotherapy in advanced lung cancer
International Nuclear Information System (INIS)
Andrade Carvalho, Heloisa de; Saito, Newton Heitetsu; Gomes, Herbeni Cardoso; Aguilar, Patricia Bailao; Nadalin, Wladimir
1996-01-01
Patients with advanced lung cancers have bad prognosis and, many times, are submitted to prolonged and not always efficient treatments. We present a study where 51 patients were treated with hypo fractionated radiotherapy, based on two distinct schemes, according to the performance status and social conditions of each patient: continuous treatment: 30 Gy, 10 fractions of 3 Gy, 5 days/week (37 cases); weekly treatment: 30 Gy, 6 fractions of 5 Gy, once a week (14 cases). Symptoms relief and impact in survival were evaluated. In both groups, we observed improvement of symptoms in about 70% of the occurrences with a medium survival of three months. We conclude that hypo fractionation is an effective palliative treatment for lung cancers, in patients with short life-expectancy and must be considered as a option in advanced cases, in patients with short life-expectancy that deserve some kind of treatment. (author). 37 refs., 2 tabs
MEERSCHAERT, MARK M.; SABZIKAR, FARZAD; CHEN, JINGHUA
2014-01-01
Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series. PMID:26085690
Meerschaert, Mark M; Sabzikar, Farzad; Chen, Jinghua
2015-07-15
Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly observed in finance. Tempered power law waiting times lead to tempered fractional time derivatives, which have proven useful in geophysics. The tempered fractional derivative or integral of a Brownian motion, called a tempered fractional Brownian motion, can exhibit semi-long range dependence. The increments of this process, called tempered fractional Gaussian noise, provide a useful new stochastic model for wind speed data. A tempered difference forms the basis for numerical methods to solve tempered fractional diffusion equations, and it also provides a useful new correlation model in time series.
Arshad, Muhammad; Lu, Dianchen; Wang, Jun
2017-07-01
In this paper, we pursue the general form of the fractional reduced differential transform method (DTM) to (N+1)-dimensional case, so that fractional order partial differential equations (PDEs) can be resolved effectively. The most distinct aspect of this method is that no prescribed assumptions are required, and the huge computational exertion is reduced and round-off errors are also evaded. We utilize the proposed scheme on some initial value problems and approximate numerical solutions of linear and nonlinear time fractional PDEs are obtained, which shows that the method is highly accurate and simple to apply. The proposed technique is thus an influential technique for solving the fractional PDEs and fractional order problems occurring in the field of engineering, physics etc. Numerical results are obtained for verification and demonstration purpose by using Mathematica software.
DEFF Research Database (Denmark)
Damgaard, Anders; Christensen, Thomas Højlund
2011-01-01
Metals like iron and aluminium are produced from mineral ore and used for a range of products, some of which have very short lifetimes and thus constitute a major fraction of municipal waste. Packaging in terms of cans, foils and containers are products with a short lifetime. Other products like...... appliances, vehicles and buildings, containing iron and aluminium metals, have long lifetimes before they end up in the waste stream. The recycling of production waste and postconsumer metals has a long history in the metal industry. Some metal smelters are today entirely based on scarp metals. This chapter...... describes briefly how iron and aluminium are produced and how scrap metal is recycled in the industry. Quality requirements and use of recycled products are discussed, as are the resource and environmental issues of metal recycling. Copper and other metals are also found in waste but in much smaller...
Tunable fractional-order Fourier transformer
International Nuclear Information System (INIS)
Malyutin, A A
2006-01-01
A fractional two-dimensional Fourier transformer whose orders are tuned by means of optical quadrupoles is described. It is shown that in the optical scheme considered, the Fourier-transform order a element of [0,1] in one of the mutually orthogonal planes corresponds to the transform order (2-a) in another plane, i.e., to inversion and inverse Fourier transform of the order a. (laser modes and beams)
An improved snow scheme for the ECMWF land surface model: Description and offline validation
Emanuel Dutra; Gianpaolo Balsamo; Pedro Viterbo; Pedro M. A. Miranda; Anton Beljaars; Christoph Schar; Kelly Elder
2010-01-01
A new snow scheme for the European Centre for Medium-Range Weather Forecasts (ECMWF) land surface model has been tested and validated. The scheme includes a new parameterization of snow density, incorporating a liquid water reservoir, and revised formulations for the subgrid snow cover fraction and snow albedo. Offline validation (covering a wide range of spatial and...
Transmission usage cost allocation schemes
International Nuclear Information System (INIS)
Abou El Ela, A.A.; El-Sehiemy, R.A.
2009-01-01
This paper presents different suggested transmission usage cost allocation (TCA) schemes to the system individuals. Different independent system operator (ISO) visions are presented using the proportional rata and flow-based TCA methods. There are two proposed flow-based TCA schemes (FTCA). The first FTCA scheme generalizes the equivalent bilateral exchanges (EBE) concepts for lossy networks through two-stage procedure. The second FTCA scheme is based on the modified sensitivity factors (MSF). These factors are developed from the actual measurements of power flows in transmission lines and the power injections at different buses. The proposed schemes exhibit desirable apportioning properties and are easy to implement and understand. Case studies for different loading conditions are carried out to show the capability of the proposed schemes for solving the TCA problem. (author)
MEERSCHAERT, MARK M.; SABZIKAR, FARZAD; CHEN, JINGHUA
2015-01-01
Fractional derivatives and integrals are convolutions with a power law. Multiplying by an exponential factor leads to tempered fractional derivatives and integrals. Tempered fractional diffusion equations, where the usual second derivative in space is replaced by a tempered fractional derivative, govern the limits of random walk models with an exponentially tempered power law jump distribution. The limiting tempered stable probability densities exhibit semi-heavy tails, which are commonly obs...
Patrick Honohan
1987-01-01
A Ponzi scheme is an arrangement whereby a promoter offers an investment opportunity with attractive dividends, but where the only basis for the dividends is the future receipts from new investors. The first of these two notes explores some of the analytical properties of a Ponzi scheme, addressing in particular the question whether it is possible for a Ponzi scheme to exist if all the participants are rational. The second note briefly examines the collapse of the PMPA insurance company whos...
DEFF Research Database (Denmark)
Hansen, Elo Harald
Despite its excellent analytical chemical capacity, ICPMS (and also ETAAS), nevertheless, often requires suitable pretreatment of the sample material to facilitate the desired sensitivity and selectivity of measurement. Either because of the presence of potentially interfering matrix constituents...... as these adversely will impair its performance. In the lecture, selected examples of separation/preconcentration FI/SI-procedures for the determination of trace levels of metals will be presented, particular emphasis being placed on the use of the novel “lab-on-valve” (LOV) concept....
fractional differential equations
Indian Academy of Sciences (India)
We apply this method for solving space–time fractional Cahn--Allen equation and space--time fractional Klein–Gordon equation. The fractional derivatives are described in the sense of modified Riemann--Lioville. As a result of some exact solution in the form of hyperbolic, trigonometric and rational solutions are deduced.
Unfolding Fraction Multiplication
Wyberg, Terry; Whitney, Stephanie R.; Cramer, Kathleen A.; Monson, Debra S.; Leavitt, Seth
2011-01-01
Students often have difficulty understanding fractions, in general, and understanding how to multiply fractions, in particular. To move past this potential problem area, students need to develop a deeper understanding of multiplication and connect the ideas to fractions. In this article, the authors share their insights into teaching fraction…
Entropy conservative finite element schemes
Tadmor, E.
1986-01-01
The question of entropy stability for discrete approximations to hyperbolic systems of conservation laws is studied. The amount of numerical viscosity present in such schemes is quantified and related to their entropy stability by means of comparison. To this end, two main ingredients are used: entropy variables and the construction of certain entropy conservative schemes in terms of piecewise-linear finite element approximations. It is then shown that conservative schemes are entropy stable, if and (for three-point schemes) only if, they contain more numerical viscosity than the abovementioned entropy conservation ones.
DEFF Research Database (Denmark)
Rotbart, Noy Galil
in a distributed fashion increases. Second, attempting to answer queries on vertices of a graph stored in a distributed fashion can be significantly more complicated. In order to lay theoretical foundations to the first penalty mentioned a large body of work concentrated on labeling schemes. A labeling scheme...... evaluation of fully dynamic labeling schemes. Due to a connection between adjacency labeling schemes and the graph theoretical study of induced universal graphs, we study these in depth and show novel results for bounded degree graphs and power-law graphs. We also survey and make progress on the related...
A fabrication scheme for biomimetic aquatic hair sensors
Izadi, N.; de Boer, Meint J.; Berenschot, Johan W.; Wiegerink, Remco J.; Krijnen, Gijsbertus J.M.
2009-01-01
A fabrication scheme to realize a flow sensor array for operation in liquid which biomimics fish lateral line is presented. The configuration enables differential capacitive sensing upon rotation of the metal electrodes under the membrane due to deflection of a receptive hair by drag force of the
Interface control scheme for computer high-speed interface unit
Ballard, B. K.
1975-01-01
Control scheme is general and performs for multiplexed and dedicated channels as well as for data-bus interfaces. Control comprises two 64-pin, dual in-line packages, each of which holds custom large-scale integrated array built with silicon-on-sapphire complementary metal-oxide semiconductor technology.
Efficient Scheme for Chemical Flooding Simulation
Directory of Open Access Journals (Sweden)
Braconnier Benjamin
2014-07-01
Full Text Available In this paper, we investigate an efficient implicit scheme for the numerical simulation of chemical enhanced oil recovery technique for oil fields. For the sake of brevity, we only focus on flows with polymer to describe the physical and numerical models. In this framework, we consider a black oil model upgraded with the polymer modeling. We assume the polymer only transported in the water phase or adsorbed on the rock following a Langmuir isotherm. The polymer reduces the water phase mobility which can change drastically the behavior of water oil interfaces. Then, we propose a fractional step technique to resolve implicitly the system. The first step is devoted to the resolution of the black oil subsystem and the second to the polymer mass conservation. In such a way, jacobian matrices coming from the implicit formulation have a moderate size and preserve solvers efficiency. Nevertheless, the coupling between the black-oil subsystem and the polymer is not fully resolved. For efficiency and accuracy comparison, we propose an explicit scheme for the polymer for which large time step is prohibited due to its CFL (Courant-Friedrichs-Levy criterion and consequently approximates accurately the coupling. Numerical experiments with polymer are simulated : a core flood, a 5-spot reservoir with surfactant and ions and a 3D real case. Comparisons are performed between the polymer explicit and implicit scheme. They prove that our polymer implicit scheme is efficient, robust and resolves accurately the coupling physics. The development and the simulations have been performed with the software PumaFlow [PumaFlow (2013 Reference manual, release V600, Beicip Franlab].
Characteristic of student’s false concessive failure on fractions concept
Kurniawan, H.; Sutawidjaja, A.; As’ari, A. R.; Muksar, M.
2018-03-01
False concessive failure of students is students construction failure in achieving goals, where the process is false, the results obtained is true. This failure occurs because the schemes are not connected to each other, so it cannot form a new scheme. This research is a qualitative research that aim to describe the characteristics of students' false concessive failure on fractional concepts. This fractional concept is a fraction of the same part of the whole. To be able to solve the concept of this fraction, students must possess the concept of partition, the concept of addition and the concept of multiplication of the fraction.
hybrid modulation scheme fo rid modulation scheme fo dulation ...
African Journals Online (AJOL)
eobe
This work proposes a switching technique for ca proposes a switching technique for ca. (SCSPWM) scheme is employed in the generation circulation schemes are presented for this concepts, it is now possible to generate equal ave pts, it is now possible to generate equal ave semiconductor switches. This results in equal ...
Shamim, Atif
2011-03-01
For the first time, a generalized Smith chart is introduced here to represent fractional order circuit elements. It is shown that the standard Smith chart is a special case of the generalized fractional order Smith chart. With illustrations drawn for both the conventional integer based lumped elements and the fractional elements, a graphical technique supported by the analytical method is presented to plot impedances on the fractional Smith chart. The concept is then applied towards impedance matching networks, where the fractional approach proves to be much more versatile and results in a single element matching network for a complex load as compared to the two elements in the conventional approach. © 2010 IEEE.
Electronically Tunable Fully Integrated Fractional-Order Resonator
Tsirimokou, Georgia
2017-03-20
A fully integrated implementation of a parallel fractional-order resonator which employs together a fractional order capacitor and a fractional-order inductor is proposed in this paper. The design utilizes current-controlled Operational Transconductance Amplifiers as building blocks, designed and fabricated in AMS 0:35m CMOS process, and based on a second-order approximation of a fractional-order differentiator/ integrator magnitude optimized in the range 10Hz–700Hz. An attractive benefit of the proposed scheme is its electronic tuning capability.
Finite element method for time-space-fractional Schrodinger equation
Directory of Open Access Journals (Sweden)
Xiaogang Zhu
2017-07-01
Full Text Available In this article, we develop a fully discrete finite element method for the nonlinear Schrodinger equation (NLS with time- and space-fractional derivatives. The time-fractional derivative is described in Caputo's sense and the space-fractional derivative in Riesz's sense. Its stability is well derived; the convergent estimate is discussed by an orthogonal operator. We also extend the method to the two-dimensional time-space-fractional NLS and to avoid the iterative solvers at each time step, a linearized scheme is further conducted. Several numerical examples are implemented finally, which confirm the theoretical results as well as illustrate the accuracy of our methods.
Dey, Aloke
2009-01-01
A one-stop reference to fractional factorials and related orthogonal arrays.Presenting one of the most dynamic areas of statistical research, this book offers a systematic, rigorous, and up-to-date treatment of fractional factorial designs and related combinatorial mathematics. Leading statisticians Aloke Dey and Rahul Mukerjee consolidate vast amounts of material from the professional literature--expertly weaving fractional replication, orthogonal arrays, and optimality aspects. They develop the basic theory of fractional factorials using the calculus of factorial arrangements, thereby providing a unified approach to the study of fractional factorial plans. An indispensable guide for statisticians in research and industry as well as for graduate students, Fractional Factorial Plans features: * Construction procedures of symmetric and asymmetric orthogonal arrays. * Many up-to-date research results on nonexistence. * A chapter on optimal fractional factorials not based on orthogonal arrays. * Trend-free plans...
Fractional Dynamics and Control
Machado, José; Luo, Albert
2012-01-01
Fractional Dynamics and Control provides a comprehensive overview of recent advances in the areas of nonlinear dynamics, vibration and control with analytical, numerical, and experimental results. This book provides an overview of recent discoveries in fractional control, delves into fractional variational principles and differential equations, and applies advanced techniques in fractional calculus to solving complicated mathematical and physical problems.Finally, this book also discusses the role that fractional order modeling can play in complex systems for engineering and science. Discusses how fractional dynamics and control can be used to solve nonlinear science and complexity issues Shows how fractional differential equations and models can be used to solve turbulence and wave equations in mechanics and gravity theories and Schrodinger’s equation Presents factional relaxation modeling of dielectric materials and wave equations for dielectrics Develops new methods for control and synchronization of...
CANONICAL BACKWARD DIFFERENTIATION SCHEMES FOR ...
African Journals Online (AJOL)
The schemes are based on rational interpolation obtained from canonical polynomials. They are A-stable. The test problems show that they give better results than Euler backward method and trapezoidal method near a singular point. KEY WORDS: backward differentiation scheme, collocation, initial value problems.
Energy Technology Data Exchange (ETDEWEB)
Clemente Gutierrez, F.; Perez Vara, C.; Prieto Villacorta, M.
2013-07-01
Several studies have been proposed over the years schemes of hypo-fractionated treatment for prostate cancer. Such schemes have been designed in order to increase local control of the disease and reduce complications. They are in addition a clear improvement from the point of view logistical and organizational for treatment centres and the patient. the hypo-fractionated treatments are possible because the ratio a/b for prostate carcinoma is comparable, and even below, the surrounding healthy tissues. This work presents the scheme adopted in our Center for the hypo-fractionated treatment of the cancer of prostate by arco therapy volumetric modulated. (Author)
Spectral scheme for spacetime physics
International Nuclear Information System (INIS)
Seriu, Masafumi
2002-01-01
Based on the spectral representation of spatial geometry, we construct an analysis scheme for spacetime physics and cosmology, which enables us to compare two or more universes with each other. In this scheme the spectral distance plays a central role, which is the measure of closeness between two geometries defined in terms of the spectra. We apply this scheme for analyzing the averaging problem in cosmology; we explicitly investigate the time evolution of the spectra, distance between two nearby spatial geometries, simulating the relation between the real Universe and its model. We then formulate the criteria for a model to be a suitable one
Coordinated renewable energy support schemes
DEFF Research Database (Denmark)
Morthorst, P.E.; Jensen, S.G.
2006-01-01
This paper illustrates the effect that can be observed when support schemes for renewable energy are regionalised. Two theoretical examples are used to explain interactive effects on, e.g., the price of power, conditions for conventional power producers, and changes in import and export of power...... RES-E support schemes already has a common liberalised power market. In this case the introduction of a common support scheme for renewable technologies will lead to more efficient sitings of renewable plants, improving economic and environmental performance of the total power system...
Auction dynamics: A volume constrained MBO scheme
Jacobs, Matt; Merkurjev, Ekaterina; Esedoǧlu, Selim
2018-02-01
We show how auction algorithms, originally developed for the assignment problem, can be utilized in Merriman, Bence, and Osher's threshold dynamics scheme to simulate multi-phase motion by mean curvature in the presence of equality and inequality volume constraints on the individual phases. The resulting algorithms are highly efficient and robust, and can be used in simulations ranging from minimal partition problems in Euclidean space to semi-supervised machine learning via clustering on graphs. In the case of the latter application, numerous experimental results on benchmark machine learning datasets show that our approach exceeds the performance of current state-of-the-art methods, while requiring a fraction of the computation time.
Assessment of Heavy Metal Pollution in Sediment and Polychaete ...
African Journals Online (AJOL)
HEAVY METAL POLLUTION & POLYCHAETE WORMS FROM MZINGA CREEK & RAS DEGE MANGROVE ECOSYSTEM. 125 ... metal pollution. The concentration of metals in the geochemically available sediment fraction (easily reducible and oxidisable phases) is analysed to assess the ..... River inputs to the ocean.
Series Solutions of Time-Fractional Host-Parasitoid Systems
Arafa, A. A. M.
2011-12-01
In this paper, Adomian's decomposition method (ADM) has been used for solving time-fractional host-parasitoid system. The derivatives are understood in the Caputo sense. The reason of using fractional order differential equations (FOD) is that FOD are naturally related to systems with memory which exists in most biological systems. Also they are closely related to fractals which are abundant in biological systems. Numerical example justifies the proposed scheme.
Benson, Nsikak U; Asuquo, Francis E; Williams, Akan B; Essien, Joseph P; Ekong, Cyril I; Akpabio, Otobong; Olajire, Abaas A
2016-01-01
Trace metals (Cd, Cr, Cu, Ni and Pb) concentrations in benthic sediments were analyzed through multi-step fractionation scheme to assess the levels and sources of contamination in estuarine, riverine and freshwater ecosystems in Niger Delta (Nigeria). The degree of contamination was assessed using the individual contamination factors (ICF) and global contamination factor (GCF). Multivariate statistical approaches including principal component analysis (PCA), cluster analysis and correlation test were employed to evaluate the interrelationships and associated sources of contamination. The spatial distribution of metal concentrations followed the pattern Pb>Cu>Cr>Cd>Ni. Ecological risk index by ICF showed significant potential mobility and bioavailability for Cu, Cu and Ni. The ICF contamination trend in the benthic sediments at all studied sites was Cu>Cr>Ni>Cd>Pb. The principal component and agglomerative clustering analyses indicate that trace metals contamination in the ecosystems was influenced by multiple pollution sources.
Directory of Open Access Journals (Sweden)
Nsikak U Benson
Full Text Available Trace metals (Cd, Cr, Cu, Ni and Pb concentrations in benthic sediments were analyzed through multi-step fractionation scheme to assess the levels and sources of contamination in estuarine, riverine and freshwater ecosystems in Niger Delta (Nigeria. The degree of contamination was assessed using the individual contamination factors (ICF and global contamination factor (GCF. Multivariate statistical approaches including principal component analysis (PCA, cluster analysis and correlation test were employed to evaluate the interrelationships and associated sources of contamination. The spatial distribution of metal concentrations followed the pattern Pb>Cu>Cr>Cd>Ni. Ecological risk index by ICF showed significant potential mobility and bioavailability for Cu, Cu and Ni. The ICF contamination trend in the benthic sediments at all studied sites was Cu>Cr>Ni>Cd>Pb. The principal component and agglomerative clustering analyses indicate that trace metals contamination in the ecosystems was influenced by multiple pollution sources.
Relaxation schemes for Chebyshev spectral multigrid methods
Kang, Yimin; Fulton, Scott R.
1993-01-01
Two relaxation schemes for Chebyshev spectral multigrid methods are presented for elliptic equations with Dirichlet boundary conditions. The first scheme is a pointwise-preconditioned Richardson relaxation scheme and the second is a line relaxation scheme. The line relaxation scheme provides an efficient and relatively simple approach for solving two-dimensional spectral equations. Numerical examples and comparisons with other methods are given.
Good governance for pension schemes
Thornton, Paul
2011-01-01
Regulatory and market developments have transformed the way in which UK private sector pension schemes operate. This has increased demands on trustees and advisors and the trusteeship governance model must evolve in order to remain fit for purpose. This volume brings together leading practitioners to provide an overview of what today constitutes good governance for pension schemes, from both a legal and a practical perspective. It provides the reader with an appreciation of the distinctive characteristics of UK occupational pension schemes, how they sit within the capital markets and their social and fiduciary responsibilities. Providing a holistic analysis of pension risk, both from the trustee and the corporate perspective, the essays cover the crucial role of the employer covenant, financing and investment risk, developments in longevity risk hedging and insurance de-risking, and best practice scheme administration.
A Novel Iris Segmentation Scheme
Directory of Open Access Journals (Sweden)
Chen-Chung Liu
2014-01-01
Full Text Available One of the key steps in the iris recognition system is the accurate iris segmentation from its surrounding noises including pupil, sclera, eyelashes, and eyebrows of a captured eye-image. This paper presents a novel iris segmentation scheme which utilizes the orientation matching transform to outline the outer and inner iris boundaries initially. It then employs Delogne-Kåsa circle fitting (instead of the traditional Hough transform to further eliminate the outlier points to extract a more precise iris area from an eye-image. In the extracted iris region, the proposed scheme further utilizes the differences in the intensity and positional characteristics of the iris, eyelid, and eyelashes to detect and delete these noises. The scheme is then applied on iris image database, UBIRIS.v1. The experimental results show that the presented scheme provides a more effective and efficient iris segmentation than other conventional methods.
Fractional and noncommutative spacetimes
Arzano, M.|info:eu-repo/dai/nl/32616443X; Calcagni, M.; Oriti, D.; Scalisi, M.
2011-01-01
We establish a mapping between fractional and noncommutative spacetimes in configuration space. Depending on the scale at which the relation is considered, there arise two possibilities. For a fractional spacetime with log-oscillatory measure, the effective measure near the fundamental scale
A.I. Barros (Ana); J.B.G. Frenk (Hans); J.A.S. Gromicho (Joaquim)
1997-01-01
textabstractIn this paper we analyze some variants of the classical uncapacitated facility location problem with a ratio as an objective function. Using basic concepts and results of fractional programming, we identify a class of one-level fractional location problems which can be solved in
Wilkerson, Trena L.; Bryan, Tommy; Curry, Jane
2012-01-01
This article describes how using candy bars as models gives sixth-grade students a taste for learning to represent fractions whose denominators are factors of twelve. Using paper models of the candy bars, students explored and compared fractions. They noticed fewer different representations for one-third than for one-half. The authors conclude…
Numerical schemes for explosion hazards
International Nuclear Information System (INIS)
Therme, Nicolas
2015-01-01
In nuclear facilities, internal or external explosions can cause confinement breaches and radioactive materials release in the environment. Hence, modeling such phenomena is crucial for safety matters. Blast waves resulting from explosions are modeled by the system of Euler equations for compressible flows, whereas Navier-Stokes equations with reactive source terms and level set techniques are used to simulate the propagation of flame front during the deflagration phase. The purpose of this thesis is to contribute to the creation of efficient numerical schemes to solve these complex models. The work presented here focuses on two major aspects: first, the development of consistent schemes for the Euler equations, then the buildup of reliable schemes for the front propagation. In both cases, explicit in time schemes are used, but we also introduce a pressure correction scheme for the Euler equations. Staggered discretization is used in space. It is based on the internal energy formulation of the Euler system, which insures its positivity and avoids tedious discretization of the total energy over staggered grids. A discrete kinetic energy balance is derived from the scheme and a source term is added in the discrete internal energy balance equation to preserve the exact total energy balance at the limit. High order methods of MUSCL type are used in the discrete convective operators, based solely on material velocity. They lead to positivity of density and internal energy under CFL conditions. This ensures that the total energy cannot grow and we can furthermore derive a discrete entropy inequality. Under stability assumptions of the discrete L8 and BV norms of the scheme's solutions one can prove that a sequence of converging discrete solutions necessarily converges towards the weak solution of the Euler system. Besides it satisfies a weak entropy inequality at the limit. Concerning the front propagation, we transform the flame front evolution equation (the so
Breeding schemes in reindeer husbandry
Directory of Open Access Journals (Sweden)
Lars Rönnegård
2003-04-01
Full Text Available The objective of the paper was to investigate annual genetic gain from selection (G, and the influence of selection on the inbreeding effective population size (Ne, for different possible breeding schemes within a reindeer herding district. The breeding schemes were analysed for different proportions of the population within a herding district included in the selection programme. Two different breeding schemes were analysed: an open nucleus scheme where males mix and mate between owner flocks, and a closed nucleus scheme where the males in non-selected owner flocks are culled to maximise G in the whole population. The theory of expected long-term genetic contributions was used and maternal effects were included in the analyses. Realistic parameter values were used for the population, modelled with 5000 reindeer in the population and a sex ratio of 14 adult females per male. The standard deviation of calf weights was 4.1 kg. Four different situations were explored and the results showed: 1. When the population was randomly culled, Ne equalled 2400. 2. When the whole population was selected on calf weights, Ne equalled 1700 and the total annual genetic gain (direct + maternal in calf weight was 0.42 kg. 3. For the open nucleus scheme, G increased monotonically from 0 to 0.42 kg as the proportion of the population included in the selection programme increased from 0 to 1.0, and Ne decreased correspondingly from 2400 to 1700. 4. In the closed nucleus scheme the lowest value of Ne was 1300. For a given proportion of the population included in the selection programme, the difference in G between a closed nucleus scheme and an open one was up to 0.13 kg. We conclude that for mass selection based on calf weights in herding districts with 2000 animals or more, there are no risks of inbreeding effects caused by selection.
Small-scale classification schemes
DEFF Research Database (Denmark)
Hertzum, Morten
2004-01-01
. While coordination mechanisms focus on how classification schemes enable cooperation among people pursuing a common goal, boundary objects embrace the implicit consequences of classification schemes in situations involving conflicting goals. Moreover, the requirements specification focused on functional...... requirements and provided little information about why these requirements were considered relevant. This stands in contrast to the discussions at the project meetings where the software engineers made frequent use of both abstract goal descriptions and concrete examples to make sense of the requirements...
Mustapha, K.
2017-06-03
Anomalous diffusion is a phenomenon that cannot be modeled accurately by second-order diffusion equations, but is better described by fractional diffusion models. The nonlocal nature of the fractional diffusion operators makes substantially more difficult the mathematical analysis of these models and the establishment of suitable numerical schemes. This paper proposes and analyzes the first finite difference method for solving {\\\\em variable-coefficient} fractional differential equations, with two-sided fractional derivatives, in one-dimensional space. The proposed scheme combines first-order forward and backward Euler methods for approximating the left-sided fractional derivative when the right-sided fractional derivative is approximated by two consecutive applications of the first-order backward Euler method. Our finite difference scheme reduces to the standard second-order central difference scheme in the absence of fractional derivatives. The existence and uniqueness of the solution for the proposed scheme are proved, and truncation errors of order $h$ are demonstrated, where $h$ denotes the maximum space step size. The numerical tests illustrate the global $O(h)$ accuracy of our scheme, except for nonsmooth cases which, as expected, have deteriorated convergence rates.
Diaz, Victor Alfonzo; Giusti, Andrea
2018-03-01
The aim of this paper is to present a simple generalization of bosonic string theory in the framework of the theory of fractional variational problems. Specifically, we present a fractional extension of the Polyakov action, for which we compute the general form of the equations of motion and discuss the connection between the new fractional action and a generalization the Nambu-Goto action. Consequently, we analyze the symmetries of the modified Polyakov action and try to fix the gauge, following the classical procedures. Then we solve the equations of motion in a simplified setting. Finally, we present a Hamiltonian description of the classical fractional bosonic string and introduce the fractional light-cone gauge. It is important to remark that, throughout the whole paper, we thoroughly discuss how to recover the known results as an "integer" limit of the presented model.
Kinetic scheme of biomass pyrolysis considering secondary charring reactions
International Nuclear Information System (INIS)
Anca-Couce, Andrés; Mehrabian, Ramin; Scharler, Robert; Obernberger, Ingwald
2014-01-01
Highlights: • A mechanistic scheme for biomass pyrolysis from the literature is adapted. • Secondary char formation reactions and catalytic effect of alkalis are considered. • The adapted scheme is validated with experimental data from the literature. - Abstract: A widely applicable kinetic scheme for pyrolysis is still missing. In this work an adaptation of the mechanistic scheme developed by Ranzi et al. (2008) for pyrolysis of small ash free biomass particles is proposed. The scheme is modified to include secondary char formation reactions, which are relevant for particles of a certain thickness, and sugar formation is avoided due to the catalytic effect of alkali metals in biomass. The predictions of the adapted scheme are compared to experimental data from the literature of pyrolysis in fixed beds of particles with a size of around 1 cm. It is shown that the adaptation improves the prediction of the final char yield and its CHO composition and also the yields of the main groups of volatiles, as carbonyls + alcohols, sugars and water vapor
Hybrid flux splitting schemes for numerical resolution of two-phase flows
Energy Technology Data Exchange (ETDEWEB)
Flaatten, Tore
2003-07-01
This thesis deals with the construction of numerical schemes for approximating. solutions to a hyperbolic two-phase flow model. Numerical schemes for hyperbolic models are commonly divided in two main classes: Flux Vector Splitting (FVS) schemes which are based on scalar computations and Flux Difference Splitting (FDS) schemes which are based on matrix computations. FVS schemes are more efficient than FDS schemes, but FDS schemes are more accurate. The canonical FDS schemes are the approximate Riemann solvers which are based on a local decomposition of the system into its full wave structure. In this thesis the mathematical structure of the model is exploited to construct a class of hybrid FVS/FDS schemes, denoted as Mixture Flux (MF) schemes. This approach is based on a splitting of the system in two components associated with the pressure and volume fraction variables respectively, and builds upon hybrid FVS/FDS schemes previously developed for one-phase flow models. Through analysis and numerical experiments it is demonstrated that the MF approach provides several desirable features, including (1) Improved efficiency compared to standard approximate Riemann solvers, (2) Robustness under stiff conditions, (3) Accuracy on linear and nonlinear phenomena. In particular it is demonstrated that the framework allows for an efficient weakly implicit implementation, focusing on an accurate resolution of slow transients relevant for the petroleum industry. (author)
Remote automatic control scheme for plasma arc cutting of contaminated waste
International Nuclear Information System (INIS)
Dudar, A.M.; Ward, C.R.; Kriikku, E.M.
1993-01-01
The Robotics Development Group at the Savannah River Technology Center has developed and implemented a scheme to perform automatic cutting of metallic contaminated waste. The scheme employs a plasma arc cutter in conjunction with a laser ranging sensor attached to a robotic manipulator called the Telerobot. A software algorithm using proportional control is then used to perturb the robot's trajectory in such a way as to regulate the plasma arc standoff and the robot's speed in order to achieve automatic plasma arc cuts. The scheme has been successfully tested on simulated waste materials and the results have been very favorable. This report details the development and testing of the scheme
Fresh Bottom Ash Characteristics Dependence on Fractional Composition
Jurgita Seniūnaitė; Saulius Vasarevičius
2017-01-01
Waste incineration process generates two main by-products streams: fly ash and bottom ash. Bottom ash is composed of a variety of oxides, heavy metals and salts. Chemical materials distributed unevenly in different fractions of bottom ash. This study investigates the heavy metals (Pb, Cd) content dependence of bottom ash and fraction composition. Studies were performed with five different fractions (0–2 mm; 2–5.6 mm; 5.6–11.2 mm; 11.2–22,4 mm; 22.4–40 mm) of fresh bottom ash. After a one-step...
Fractional Order Generalized Information
Directory of Open Access Journals (Sweden)
José Tenreiro Machado
2014-04-01
Full Text Available This paper formulates a novel expression for entropy inspired in the properties of Fractional Calculus. The characteristics of the generalized fractional entropy are tested both in standard probability distributions and real world data series. The results reveal that tuning the fractional order allow an high sensitivity to the signal evolution, which is useful in describing the dynamics of complex systems. The concepts are also extended to relative distances and tested with several sets of data, confirming the goodness of the generalization.
Dual beam encoded extended fractional Fourier transform security ...
Indian Academy of Sciences (India)
Holograms; security holograms; optical security; extended fractional Fourier transforms. PACS Nos 42.40.-i; 42.40. ... cost-effective scheme for the development of security hologram, we noticed that two reference beams holography [10] can ..... couragement, support and for permission to publish this work. They wish to thank.
Particle Simulation of Fractional Diffusion Equations
Allouch, Samer
2017-07-12
This work explores different particle-based approaches to the simulation of one-dimensional fractional subdiffusion equations in unbounded domains. We rely on smooth particle approximations, and consider four methods for estimating the fractional diffusion term. The first method is based on direct differentiation of the particle representation, it follows the Riesz definition of the fractional derivative and results in a non-conservative scheme. The other three methods follow the particle strength exchange (PSE) methodology and are by construction conservative, in the sense that the total particle strength is time invariant. The first PSE algorithm is based on using direct differentiation to estimate the fractional diffusion flux, and exploiting the resulting estimates in an integral representation of the divergence operator. Meanwhile, the second one relies on the regularized Riesz representation of the fractional diffusion term to derive a suitable interaction formula acting directly on the particle representation of the diffusing field. A third PSE construction is considered that exploits the Green\\'s function of the fractional diffusion equation. The performance of all four approaches is assessed for the case of a one-dimensional diffusion equation with constant diffusivity. This enables us to take advantage of known analytical solutions, and consequently conduct a detailed analysis of the performance of the methods. This includes a quantitative study of the various sources of error, namely filtering, quadrature, domain truncation, and time integration, as well as a space and time self-convergence analysis. These analyses are conducted for different values of the order of the fractional derivatives, and computational experiences are used to gain insight that can be used for generalization of the present constructions.
Multiuser switched diversity scheduling schemes
Shaqfeh, Mohammad
2012-09-01
Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.
Mulugeta, Mesay; Engelsen, Christian J; Wibetoe, Grethe; Lund, Walter
2011-02-01
The release and charge-based fractionation of As, Cr, Mo, Sb, Se and V were evaluated in leachates generated from recycled concrete aggregates (RCA) in a laboratory and at a field site. The leachates, covering the pH range 8.4-12.6, were generated from non-carbonated, and artificially and naturally carbonated crushed concrete samples. Comparison between the release of the elements from the non-carbonated and carbonated samples indicated higher solubility of the elements from the latter. The laboratory leaching tests also revealed that the solubility of the elements is low at the "natural pH" of the non-carbonated materials and show enhancement when the pH is decreased. The charge-based fractionation of the elements was determined by ion-exchange solid phase extraction (SPE); it was found that all the target elements predominantly existed as anions in both the laboratory and field leachates. The high fraction of the anionic species of the elements in the leachates from the carbonated RCA materials verified the enhanced solubility of the oxyanionic species of the elements as a result of carbonation. The concentrations of the elements in the leachates and SPE effluents were determined by inductively coupled plasma mass spectrometry (ICP-MS). Copyright © 2010 Elsevier Ltd. All rights reserved.
FRACTIONS: CONCEPTUAL AND DIDACTIC ASPECTS
Directory of Open Access Journals (Sweden)
Sead Rešić
2016-09-01
Full Text Available Fractions represent the manner of writing parts of whole numbers (integers. Rules for operations with fractions differ from rules for operations with integers. Students face difficulties in understanding fractions, especially operations with fractions. These difficulties are well known in didactics of Mathematics throughout the world and there is a lot of research regarding problems in learning about fractions. Methods for facilitating understanding fractions have been discovered, which are essentially related to visualizing operations with fractions.
Fractional Stochastic Field Theory
Honkonen, Juha
2018-02-01
Models describing evolution of physical, chemical, biological, social and financial processes are often formulated as differential equations with the understanding that they are large-scale equations for averages of quantities describing intrinsically random processes. Explicit account of randomness may lead to significant changes in the asymptotic behaviour (anomalous scaling) in such models especially in low spatial dimensions, which in many cases may be captured with the use of the renormalization group. Anomalous scaling and memory effects may also be introduced with the use of fractional derivatives and fractional noise. Construction of renormalized stochastic field theory with fractional derivatives and fractional noise in the underlying stochastic differential equations and master equations and the interplay between fluctuation-induced and built-in anomalous scaling behaviour is reviewed and discussed.
Social Trust and Fractionalization:
DEFF Research Database (Denmark)
Bjørnskov, Christian
2008-01-01
a much larger country sample than in previous literature confirms that fractionalization in the form of income inequality and political diversity adversely affects social trust while ethnic diversity does not. However, these effects differ systematically across countries, questioning standard...
Fractional excretion of sodium
FE sodium; FENa ... a lab. There, they are examined for salt (sodium) and creatinine levels. Creatinine is a chemical waste ... Chernecky CC, Berger BJ. Excretion fraction of filtered sodium-blood and urine. In: Chernecky CC, Berger BJ, ...
Goodrich, Christopher
2015-01-01
This text provides the first comprehensive treatment of the discrete fractional calculus. Experienced researchers will find the text useful as a reference for discrete fractional calculus and topics of current interest. Students who are interested in learning about discrete fractional calculus will find this text to provide a useful starting point. Several exercises are offered at the end of each chapter and select answers have been provided at the end of the book. The presentation of the content is designed to give ample flexibility for potential use in a myriad of courses and for independent study. The novel approach taken by the authors includes a simultaneous treatment of the fractional- and integer-order difference calculus (on a variety of time scales, including both the usual forward and backwards difference operators). The reader will acquire a solid foundation in the classical topics of the discrete calculus while being introduced to exciting recent developments, bringing them to the frontiers of the...
The Local Fractional Bootstrap
DEFF Research Database (Denmark)
Bennedsen, Mikkel; Hounyo, Ulrich; Lunde, Asger
new resampling method, the local fractional bootstrap, relies on simulating an auxiliary fractional Brownian motion that mimics the fine properties of high frequency differences of the Brownian semistationary process under the null hypothesis. We prove the first order validity of the bootstrap method...... to two empirical data sets: we assess the roughness of a time series of high-frequency asset prices and we test the validity of Kolmogorov's scaling law in atmospheric turbulence data....
Ashyralyev, Allaberen; Cakir, Zafer
2016-08-01
In this work, we investigate initial-boundary value problems for fractional parabolic equations with the Neumann boundary condition. Stability estimates for the solution of this problem are established. Difference schemes for approximate solution of initial-boundary value problem are constructed. Furthermore, we give theorem on coercive stability estimates for the solution of the difference schemes.
DEFF Research Database (Denmark)
Xie, Chuan; Zhao, Xin; Savaghebi, Mehdi
2017-01-01
This paper presents a multi-rate fractional-order repetitive control (MRFORC) scheme for three-phase shunt active power filter (APF). The proposed APF control scheme includes an inner proportional-integral (PI) control loop with a sampling rate identical to switching frequency and an external plug...
An intelligent robotics control scheme
Orlando, N. E.
1984-01-01
The problem of robot control is viewed at the level of communicating high-level commands produced by intelligent algorithms to the actuator/sensor controllers. Four topics are considered in the design of an integrated control and communications scheme for an intelligent robotic system: the use of abstraction spaces, hierarchical versus heterarchical control, distributed processing, and the interleaving of the steps of plan creation and plan execution. A scheme is presented for an n-level distributed hierarchical/heterarchical control system that effectively interleaves intelligent planning, execution, and sensory feedback. A three-level version of this scheme has been successfully implemented in the Intelligent Systems Research Lab at NASA Langley Research Center. This implementation forms the control structure for DAISIE (Distributed Artificially Intelligent System for Interacting with the Environment), a testbed system integrating AI software with robotics hardware.
One-qubit fingerprinting schemes
International Nuclear Information System (INIS)
Beaudrap, J. Niel de
2004-01-01
Fingerprinting is a technique in communication complexity in which two parties (Alice and Bob) with large data sets send short messages to a third party (a referee), who attempts to compute some function of the larger data sets. For the equality function, the referee attempts to determine whether Alice's data and Bob's data are the same. In this paper, we consider the extreme scenario of performing fingerprinting where Alice and Bob both send either one bit (classically) or one qubit (in the quantum regime) messages to the referee for the equality problem. Restrictive bounds are demonstrated for the error probability of one-bit fingerprinting schemes, and show that it is easy to construct one-qubit fingerprinting schemes which can outperform any one-bit fingerprinting scheme. The author hopes that this analysis will provide results useful for performing physical experiments, which may help to advance implementations for more general quantum communication protocols
Modulation Schemes for Wireless Access
Directory of Open Access Journals (Sweden)
F. Vejrazka
2000-12-01
Full Text Available Four modulation schemes, namely minimum shift keying (MSK, Gaussianminimum shift keying (GMSK, multiamplitude minimum shift keying(MAMSK and ÃÂ€/4 differential quadrature phase shift keying (ÃÂ€/4-QPSKare described and their applicability to wireless access is discussedin the paper. Low complexity receiver structures based on differentialdetection are analysed to estimate the performance of the modulationschemes in the additive Gaussian noise and the Rayleigh and Riceenvelope fast fading channel. The bandwidth efficiency is calculated toevaluate the modulation schemes. The results show that the MAMSK schemegives the greatest bandwidth efficiency, but its performance in theRayleigh channel is rather poor. In contrast, the MSK scheme is lessbandwidth efficient, but it is more resistant to Rayleigh fading. Theperformance of ÃÂ€/4-QPSK signal is considerably improved by appropriateprefiltering.
Electrical injection schemes for nanolasers
DEFF Research Database (Denmark)
Lupi, Alexandra; Chung, Il-Sug; Yvind, Kresten
2013-01-01
injection schemes have been compared: vertical pi- n junction through a current post structure as in1 and lateral p-i-n junction with either uniform material as in2 or with a buried heterostructure (BH) as in3. To allow a direct comparison of the three schemes the same active material composition consisting......The performance of injection schemes among recently demonstrated electrically pumped photonic crystal nanolasers has been investigated numerically. The computation has been carried out at room temperature using a commercial semiconductor simulation software. For the simulations two electrical...... threshold current has been achieved with the lateral electrical injection through the BH; while the lowest resistance has been obtained from the current post structure even though this model shows a higher current threshold because of the lack of carrier confinement. Final scope of the simulations...
Simple scheme for gauge mediation
International Nuclear Information System (INIS)
Murayama, Hitoshi; Nomura, Yasunori
2007-01-01
We present a simple scheme for constructing models that achieve successful gauge mediation of supersymmetry breaking. In addition to our previous work [H. Murayama and Y. Nomura, Phys. Rev. Lett. 98, 151803 (2007)] that proposed drastically simplified models using metastable vacua of supersymmetry breaking in vectorlike theories, we show there are many other successful models using various types of supersymmetry-breaking mechanisms that rely on enhanced low-energy U(1) R symmetries. In models where supersymmetry is broken by elementary singlets, one needs to assume U(1) R violating effects are accidentally small, while in models where composite fields break supersymmetry, emergence of approximate low-energy U(1) R symmetries can be understood simply on dimensional grounds. Even though the scheme still requires somewhat small parameters to sufficiently suppress gravity mediation, we discuss their possible origins due to dimensional transmutation. The scheme accommodates a wide range of the gravitino mass to avoid cosmological problems
Electrical Injection Schemes for Nanolasers
DEFF Research Database (Denmark)
Lupi, Alexandra; Chung, Il-Sug; Yvind, Kresten
2014-01-01
Three electrical injection schemes based on recently demonstrated electrically pumped photonic crystal nanolasers have been numerically investigated: 1) a vertical p-i-n junction through a post structure; 2) a lateral p-i-n junction with a homostructure; and 3) a lateral p-i-n junction....... For this analysis, the properties of different schemes, i.e., electrical resistance, threshold voltage, threshold current, and internal efficiency as energy requirements for optical interconnects are compared and the physics behind the differences is discussed....
Screening for Proteolytic Activities in Snake Venom by Means of a Multiplexing ESI-MS Assay Scheme
Liesener, A.; Perchuc, Anna-Maria; Schöni, Reto; Wilmer, Marianne; Karst, U.
2005-01-01
A multiplexed mass spectrometry based assay scheme for the simultaneous determination of five different substrate/product pairs was developed as a tool for screening of proteolytic activities in snake venom fractions from Bothrops moojeni. The assay scheme was employed in the functional
Series expansion in fractional calculus and fractional differential equations
Li, Ming-Fan; Ren, Ji-Rong; Zhu, Tao
2009-01-01
Fractional calculus is the calculus of differentiation and integration of non-integer orders. In a recently paper (Annals of Physics 323 (2008) 2756-2778), the Fundamental Theorem of Fractional Calculus is highlighted. Based on this theorem, in this paper we introduce fractional series expansion method to fractional calculus. We define a kind of fractional Taylor series of an infinitely fractionally-differentiable function. Further, based on our definition we generalize hypergeometric functio...
Oxygen isotopic fractionation in the condensation of refractory smokes
Nelson, R.; Thiemens, M.; Nuth, J.; Donn, B.
1989-01-01
This paper reports preliminary measurements of the oxygen isotopic fractionation that occurs during the condensation of refractory metal oxide smokes. Fractionation occurred at temperatures in excess of 500 K during and/or subsequent to reaction of SiH4, Fe(CO)5, Al(CH3)3, and O2 in a H2 carrier gas. Observed isotopic fractionation was as high as -15 per mil/amu. The magnitude of the isotopic fractionation suggests that the process is kinetically controlled since the effect is greatly in excess of that expected for equilibrium isotopic exchange.
Algebraic quantization, good operators and fractional quantum numbers
International Nuclear Information System (INIS)
Aldaya, V.; Calixto, M.; Guerrero, J.
1996-01-01
The problems arising when quantizing systems with periodic boundary conditions are analysed, in an algebraic (group-) quantization scheme, and the failure of the Ehrenfest theorem is clarified in terms of the already defined notion of good (and bad) operators. The analysis of constrained Heisenberg-Weyl groups according to this quantization scheme reveals the possibility for quantum operators without classical analogue and for new quantum (fractional) numbers extending those allowed for Chern classes in traditional Geometric Quantization. This study is illustrated with the examples of the free particle on the circumference and the charged particle in a homogeneous magnetic field on the torus, both examples featuring anomalous operators, non-equivalent quantization and the latter, fractional quantum numbers. These provide the rationale behind flux quantization in superconducting rings and Fractional Quantum Hall Effect, respectively. (orig.)
Study of the AC machines winding having fractional q
Bespalov, V. Y.; Sidorov, A. O.
2018-02-01
The winding schemes with a fractional numbers of slots per pole and phase q have been known and used for a long time. However, in the literature on the low-noise machines design there are not recommended to use. Nevertheless, fractional q windings have been realized in many applications of special AC electrical machines, allowing to improve their performance, including vibroacoustic one. This paper deals with harmonic analysis of windings having integer and fractional q in permanent magnet synchronous motors, a comparison of their characteristics is performed, frequencies of subharmonics are revealed. Optimal winding pitch design is found giving reduce the amplitudes of subharmonics. Distribution factors for subharmonics, fractional and high-order harmonics are calculated, results analysis is represented, allowing for giving recommendations how to calculate distribution factors for different harmonics when q is fractional.
Active disturbance rejection control for fractional-order system.
Li, Mingda; Li, Donghai; Wang, Jing; Zhao, Chunzhe
2013-05-01
Fractional-order proportional-integral (PI) and proportional-integral-derivative (PID) controllers are the most commonly used controllers in fractional-order systems. However, this paper proposes a simple integer-order control scheme for fractional-order system based on active disturbance rejection method. By treating the fractional-order dynamics as a common disturbance and actively rejecting it, active disturbance rejection control (ADRC) can achieve the desired response. External disturbance, sensor noise, and parameter disturbance are also estimated using extended state observer. The ADRC stability of rational-order model is analyzed. Simulation results on three typical fractional-order systems are provided to demonstrate the effectiveness of the proposed method. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.
Fractional-Order Control of Pneumatic Position Servosystems
Directory of Open Access Journals (Sweden)
Cao Junyi
2011-01-01
Full Text Available A fractional-order control strategy for pneumatic position servosystem is presented in this paper. The idea of the fractional calculus application to control theory was introduced in many works, and its advantages were proved. However, the realization of fractional-order controllers for pneumatic position servosystems has not been investigated. Based on the relationship between the pressure in cylinder and the rate of mass flow into the cylinder, the dynamic model of pneumatic position servo system is established. The fractional-order controller for pneumatic position servo and its implementation in industrial computer is designed. The experiments with fractional-order controller are carried out under various conditions, which include sine position signal with different frequency and amplitude, step position signal, and variety inertial load. The results show the effectiveness of the proposed scheme and verify their fine control performance for pneumatic position servo system.
Fractional calculus in pharmacokinetics.
Sopasakis, Pantelis; Sarimveis, Haralambos; Macheras, Panos; Dokoumetzidis, Aristides
2018-02-01
We are witnessing the birth of a new variety of pharmacokinetics where non-integer-order differential equations are employed to study the time course of drugs in the body: this is dubbed "fractional pharmacokinetics". The presence of fractional kinetics has important clinical implications such as the lack of a half-life, observed, for example with the drug amiodarone and the associated irregular accumulation patterns following constant and multiple-dose administration. Building models that accurately reflect this behaviour is essential for the design of less toxic and more effective drug administration protocols and devices. This article introduces the readers to the theory of fractional pharmacokinetics and the research challenges that arise. After a short introduction to the concepts of fractional calculus, and the main applications that have appeared in literature up to date, we address two important aspects. First, numerical methods that allow us to simulate fractional order systems accurately and second, optimal control methodologies that can be used to design dosing regimens to individuals and populations.
Efficient adaptive fuzzy control scheme
Papp, Z.; Driessen, B.J.F.
1995-01-01
The paper presents an adaptive nonlinear (state-) feedback control structure, where the nonlinearities are implemented as smooth fuzzy mappings defined as rule sets. The fine tuning and adaption of the controller is realized by an indirect adaptive scheme, which modifies the parameters of the fuzzy
New practicable Siberian Snake schemes
International Nuclear Information System (INIS)
Steffen, K.
1983-07-01
Siberian Snake schemes can be inserted in ring accelerators for making the spin tune almost independent of energy. Two such schemes are here suggested which lend particularly well to practical application over a wide energy range. Being composed of horizontal and vertical bending magnets, the proposed snakes are designed to have a small maximum beam excursion in one plane. By applying in this plane a bending correction that varies with energy, they can be operated at fixed geometry in the other plane where most of the bending occurs, thus avoiding complicated magnet motion or excessively large magnet apertures that would otherwise be needed for large energy variations. The first of the proposed schemes employs a pair of standard-type Siberian Snakes, i.e. of the usual 1st and 2nd kind which rotate the spin about the longitudinal and the transverse horizontal axis, respectively. The second scheme employs a pair of novel-type snakes which rotate the spin about either one of the horizontal axes that are at 45 0 to the beam direction. In obvious reference to these axes, they are called left-pointed and right-pointed snakes. (orig.)
Homogenization scheme for acoustic metamaterials
Yang, Min
2014-02-26
We present a homogenization scheme for acoustic metamaterials that is based on reproducing the lowest orders of scattering amplitudes from a finite volume of metamaterials. This approach is noted to differ significantly from that of coherent potential approximation, which is based on adjusting the effective-medium parameters to minimize scatterings in the long-wavelength limit. With the aid of metamaterials’ eigenstates, the effective parameters, such as mass density and elastic modulus can be obtained by matching the surface responses of a metamaterial\\'s structural unit cell with a piece of homogenized material. From the Green\\'s theorem applied to the exterior domain problem, matching the surface responses is noted to be the same as reproducing the scattering amplitudes. We verify our scheme by applying it to three different examples: a layered lattice, a two-dimensional hexagonal lattice, and a decorated-membrane system. It is shown that the predicted characteristics and wave fields agree almost exactly with numerical simulations and experiments and the scheme\\'s validity is constrained by the number of dominant surface multipoles instead of the usual long-wavelength assumption. In particular, the validity extends to the full band in one dimension and to regimes near the boundaries of the Brillouin zone in two dimensions.
Wahl, Niklas; Hennig, Philipp; Wieser, Hans-Peter; Bangert, Mark
2018-04-01
We show that it is possible to explicitly incorporate fractionation effects into closed-form probabilistic treatment plan analysis and optimization for intensity-modulated proton therapy with analytical probabilistic modeling (APM). We study the impact of different fractionation schemes on the dosimetric uncertainty induced by random and systematic sources of range and setup uncertainty for treatment plans that were optimized with and without consideration of the number of treatment fractions. The APM framework is capable of handling arbitrarily correlated uncertainty models including systematic and random errors in the context of fractionation. On this basis, we construct an analytical dose variance computation pipeline that explicitly considers the number of treatment fractions for uncertainty quantitation and minimization during treatment planning. We evaluate the variance computation model in comparison to random sampling of 100 treatments for conventional and probabilistic treatment plans under different fractionation schemes (1, 5, 30 fractions) for an intracranial, a paraspinal and a prostate case. The impact of neglecting the fractionation scheme during treatment planning is investigated by applying treatment plans that were generated with probabilistic optimization for 1 fraction in a higher number of fractions and comparing them to the probabilistic plans optimized under explicit consideration of the number of fractions. APM enables the construction of an analytical variance computation model for dose uncertainty considering fractionation at negligible computational overhead. It is computationally feasible (a) to simultaneously perform a robustness analysis for all possible fraction numbers and (b) to perform a probabilistic treatment plan optimization for a specific fraction number. The incorporation of fractionation assumptions for robustness analysis exposes a dose to uncertainty trade-off, i.e., the dose in the organs at risk is increased for a
Development of an ultrasonic void fraction profiler
International Nuclear Information System (INIS)
Murai, Yuichi; Ohta, Shoko; Shigetomi, Akinari; Tasaka, Yuji; Takeda, Yasushi
2009-01-01
A method for measuring the spatial distribution of the void fraction in bubbly two-phase flow is presented. The method is referred to as ultrasonic void fraction profiling since it is based on the signal processing of an ultrasonic pulse scattering on a bubble interface. The method is established using two processes for the ultrasonic sensing of bubbles. One approach is to detect the bubble interface along a measurement line, i.e. the path of the ultrasonic pulse in the liquid. The interface is captured using two types of signal-processing schemes: the echo intensity method and the Doppler method. The other approach is to reconstruct the void fraction profile from the number of bubble interfaces. A theoretical formula for the estimation is proposed by considering ultrasonic reflection in a suspension of bubbles. The validity of the formula is examined with theoretical and numerical bases. Finally, the method developed here is applied to four flow configurations for the demonstration, in which the void fraction profile governs the modulation of liquid flow field
FRACTIONS: CONCEPTUAL AND DIDACTIC ASPECTS
Sead Rešić; Ismet Botonjić; Maid Omerović
2016-01-01
Fractions represent the manner of writing parts of whole numbers (integers). Rules for operations with fractions differ from rules for operations with integers. Students face difficulties in understanding fractions, especially operations with fractions. These difficulties are well known in didactics of Mathematics throughout the world and there is a lot of research regarding problems in learning about fractions. Methods for facilitating understanding fractions have been discovered...
Biswas, Karabi; Caponetto, Riccardo; Mendes Lopes, António; Tenreiro Machado, José António
2017-01-01
This book focuses on two specific areas related to fractional order systems – the realization of physical devices characterized by non-integer order impedance, usually called fractional-order elements (FOEs); and the characterization of vegetable tissues via electrical impedance spectroscopy (EIS) – and provides readers with new tools for designing new types of integrated circuits. The majority of the book addresses FOEs. The interest in these topics is related to the need to produce “analogue” electronic devices characterized by non-integer order impedance, and to the characterization of natural phenomena, which are systems with memory or aftereffects and for which the fractional-order calculus tool is the ideal choice for analysis. FOEs represent the building blocks for designing and realizing analogue integrated electronic circuits, which the authors believe hold the potential for a wealth of mass-market applications. The freedom to choose either an integer- or non-integer-order analogue integrator...
FRACTIONAL CRYSTALLIZATION FEED ENVELOPE
International Nuclear Information System (INIS)
HERTING DL
2008-01-01
Laboratory work was completed on a set of evaporation tests designed to establish a feed envelope for the fractional crystallization process. The feed envelope defines chemical concentration limits within which the process can be operated successfully. All 38 runs in the half-factorial design matrix were completed successfully, based on the qualitative definition of success. There is no feed composition likely to be derived from saltcake dissolution that would cause the fractional crystallization process to not meet acceptable performance requirements. However, some compositions clearly would provide more successful operation than other compositions
Singh, Phool; Yadav, A. K.; Singh, Kehar; Saini, Indu
2017-01-01
A new scheme for image encryption is proposed, using fractional Hartley transform followed by Arnold transform and singular value decomposition in the frequency domain. As the plaintext is an amplitude image, the mask used in the spatial domain is a random phase mask (RPM). The proposed scheme has been validated for grayscale images and is sensitive to the encryption parameters such as order of Arnold transform and fractional orders of the Hartley transform. We have also evaluated the scheme's resistance to the well-known noise and occlusions attacks.
Singh, Phool; Yadav, A. K.; Singh, Kehar
2017-04-01
A novel scheme for image encryption of phase images is proposed, using fractional Hartley transform followed by Arnold transform and singular value decomposition in the frequency domain. Since the plaintext is a phase image, the mask used in the spatial domain is a random amplitude mask. The proposed scheme has been validated for grayscale images and is sensitive to the encryption parameters such as the order of the Arnold transform and the fractional orders of the Hartley transform. We have also evaluated the scheme's resistance to the well-known noise and occlusion attacks.
Deficiencies of the cryptography based on multiple-parameter fractional Fourier transform.
Ran, Qiwen; Zhang, Haiying; Zhang, Jin; Tan, Liying; Ma, Jing
2009-06-01
Methods of image encryption based on fractional Fourier transform have an incipient flaw in security. We show that the schemes have the deficiency that one group of encryption keys has many groups of keys to decrypt the encrypted image correctly for several reasons. In some schemes, many factors result in the deficiencies, such as the encryption scheme based on multiple-parameter fractional Fourier transform [Opt. Lett.33, 581 (2008)]. A modified method is proposed to avoid all the deficiencies. Security and reliability are greatly improved without increasing the complexity of the encryption process. (c) 2009 Optical Society of America.
Fresh Bottom Ash Characteristics Dependence on Fractional Composition
Directory of Open Access Journals (Sweden)
Jurgita Seniūnaitė
2017-09-01
Full Text Available Waste incineration process generates two main by-products streams: fly ash and bottom ash. Bottom ash is composed of a variety of oxides, heavy metals and salts. Chemical materials distributed unevenly in different fractions of bottom ash. This study investigates the heavy metals (Pb, Cd content dependence of bottom ash and fraction composition. Studies were performed with five different fractions (0–2 mm; 2–5.6 mm; 5.6–11.2 mm; 11.2–22,4 mm; 22.4–40 mm of fresh bottom ash. After a one-step leaching test (distilled water was used as a solvent, was determinate, that highest concentrations of the lead (Pb (from 0.141 to 0.146 mg/l are leached from the smallest (0–2 mm 2–5.6 mm bottom ash fractions particles. Heavy metals concentration in these fractions eluates respectively was 2.83 and 2.91 times higher than the limit value of leaching. The highest concentration of cadmium (4.214 mg/l was determinate in 0–2 mm fraction bottom ash eluate. concentration of cadmium was 1.40 times higher than the limit value of leaching. It can be concluded that 0–2 mm; 2–5.6 mm fraction bottom ash can’t be used in civil engineering, without pre-treatment (eg. washing or aging.
Vinogradova, Natalya; Blaine, Larry
2013-01-01
Almost everyone loves chocolate. However, the same cannot be said about fractions, which are loved by markedly fewer. Middle school students tend to view them with wary respect, but little affection. The authors attempt to sweeten the subject by describing a type of game involving division of chocolate bars. The activity they describe provides a…
Fractional Differential Equation
Directory of Open Access Journals (Sweden)
Moustafa El-Shahed
2007-01-01
where 2<α<3 is a real number and D0+α is the standard Riemann-Liouville fractional derivative. Our analysis relies on Krasnoselskiis fixed point theorem of cone preserving operators. An example is also given to illustrate the main results.
Nonlinear fractional relaxation
Indian Academy of Sciences (India)
Abstract. We define a nonlinear model for fractional relaxation phenomena. We use ε-expansion method to analyse this model. By studying the fundamental solutions of this model we find that when t → 0 the model exhibits a fast decay rate and when t → ∞ the model exhibits a power-law decay. By analysing the frequency ...
Vapor liquid fraction determination
International Nuclear Information System (INIS)
1980-01-01
This invention describes a method of measuring liquid and vapor fractions in a non-homogeneous fluid flowing through an elongate conduit, such as may be required with boiling water, non-boiling turbulent flows, fluidized bed experiments, water-gas mixing analysis, and nuclear plant cooling. (UK)
Brewing with fractionated barley
Donkelaar, van L.H.G.
2016-01-01
Brewing with fractionated barley
Beer is a globally consumed beverage, which is produced from malted barley, water, hops and yeast. In recent years, the use of unmalted barley and exogenous enzymes have become more popular because they enable simpler processing and reduced environmental
Fermion Number Fractionization
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 13; Issue 8. Fermion Number Fractionization. Kumar Rao Narendra Sahu Prasanta K ... Author Affiliations. Kumar Rao1 Narendra Sahu1 Prasanta K Panigrahi1. Theoretical Physics Division, Physical Research Laboratory, Ahmedabad 380 009, India ...
Brewing with fractionated barley
Donkelaar, van L.H.G.
2016-01-01
Brewing with fractionated barley Beer is a globally consumed beverage, which is produced from malted barley, water, hops and yeast. In recent years, the use of unmalted barley and exogenous enzymes have become more popular because they enable simpler processing and reduced environmental impact. Raw
Project financing renewable energy schemes
International Nuclear Information System (INIS)
Brandler, A.
1993-01-01
The viability of many Renewable Energy projects is critically dependent upon the ability of these projects to secure the necessary financing on acceptable terms. The principal objective of the study was to provide an overview to project developers of project financing techniques and the conditions under which project finance for Renewable Energy schemes could be raised, focussing on the potential sources of finance, the typical project financing structures that could be utilised for Renewable Energy schemes and the risk/return and security requirements of lenders, investors and other potential sources of financing. A second objective is to describe the appropriate strategy and tactics for developers to adopt in approaching the financing markets for such projects. (author)
Finite volume schemes for Vlasov
Directory of Open Access Journals (Sweden)
Crouseilles Nicolas
2013-01-01
Full Text Available We present finite volume schemes for the numerical approximation of the one-dimensional Vlasov-Poisson equation (FOV CEMRACS 2011 project. Stability analysis is performed for the linear advection and links with semi-Lagrangian schemes are made. Finally, numerical results enable to compare the different methods using classical plasma test cases. Des schémas de type volumes finis sont étudiés ici pour l’approximation de l’équation de Vlasov-Poisson (projet FOV, CEMRACS 2011. Une analyse de stabilité est effectuée dans le cas de l’advection linéaire et plusieurs liens sont faits entre les méthodes volumes finis et semi-Lagrangiennes. Enfin, les méthodes sont comparées sur des cas tests académiques de la physique des plasmas.
Distance labeling schemes for trees
DEFF Research Database (Denmark)
Alstrup, Stephen; Gørtz, Inge Li; Bistrup Halvorsen, Esben
2016-01-01
We consider distance labeling schemes for trees: given a tree with n nodes, label the nodes with binary strings such that, given the labels of any two nodes, one can determine, by looking only at the labels, the distance in the tree between the two nodes. A lower bound by Gavoille et al. [Gavoille...... variants such as, for example, small distances in trees [Alstrup et al., SODA, 2003]. We improve the known upper and lower bounds of exact distance labeling by showing that 1/4 log2(n) bits are needed and that 1/2 log2(n) bits are sufficient. We also give (1 + ε)-stretch labeling schemes using Theta...
Natal-da-Luz, T.; Ojeda, G.; Costa, D.M.; Pratas, J.; Lanno, R.P.; van Gestel, C.A.M.; Sousa, J.P.
2012-01-01
Sewage sludge application to soils is regulated by its total metal content. However, the real risk of metals is determined by the fraction that is biologically available. The available fraction is highly related to the strength of metal binding by the matrix, which is a dynamic process. The
Perturbation of Fractional Multi-Agent Systems in Cloud Entropy Computing
Directory of Open Access Journals (Sweden)
Rabha W. Ibrahim
2016-01-01
Full Text Available A perturbed multi-agent system is a scheme self-possessed of multiple networking agents within a location. This scheme can be used to discuss problems that are impossible or difficult for a specific agent to solve. Intelligence cloud entropy management systems involve functions, methods, procedural approaches, and algorithms. In this study, we introduce a new perturbed algorithm based on the fractional Poisson process. The discrete dynamics are suggested by using fractional entropy and fractional type Tsallis entropy. Moreover, we study the algorithm stability.
A 3D Fractional-Order Chaotic System with Only One Stable Equilibrium and Controlling Chaos
Directory of Open Access Journals (Sweden)
Shiyun Shen
2017-01-01
Full Text Available One 3D fractional-order chaotic system with only one locally asymptotically stable equilibrium is reported. To verify the chaoticity, the maximum Lyapunov exponent (MAXLE with respect to the fractional-order and chaotic attractors are obtained by numerical calculation for this system. Furthermore, by linear scalar controller consisting of a single state variable, one control scheme for stabilization of the 3D fractional-order chaotic system is suggested. The numerical simulations show the feasibility of the control scheme.
A Fully Discrete Galerkin Method for a Nonlinear Space-Fractional Diffusion Equation
Directory of Open Access Journals (Sweden)
Yunying Zheng
2011-01-01
Full Text Available The spatial transport process in fractal media is generally anomalous. The space-fractional advection-diffusion equation can be used to characterize such a process. In this paper, a fully discrete scheme is given for a type of nonlinear space-fractional anomalous advection-diffusion equation. In the spatial direction, we use the finite element method, and in the temporal direction, we use the modified Crank-Nicolson approximation. Here the fractional derivative indicates the Caputo derivative. The error estimate for the fully discrete scheme is derived. And the numerical examples are also included which are in line with the theoretical analysis.
New schemes for particle accelerators
International Nuclear Information System (INIS)
Nishida, Y.
1985-01-01
In the present paper, the authors propose new schemes for realizing the v/sub p/xB accelerator, by using no plasma system for producing the strong longitudinal waves. The first method is to use a grating for obtaining extended interaction of an electron beam moving along the grating surface with light beam incident also along the surface. Here, the light beam propagates obliquely to the grating grooves for producing strong electric field, and the electron beam propagates in parallel to the light beam. The static magnetic field is applied perpendicularly to the grating surface. In the present system, the beam interacts synchronously with the p-polarized wave which has the electric field be parallel to the grating surface. Another conventional scheme is to use a delay circuit. Here, the light beam propagates obliquely between a pair of array of conductor fins or slots. The phase velocity of the spatial harmonics in the y-direction (right angle to the array of slots) is slower than the speed of light. With the aid of powerful laser light or microwave source, it should be possible to miniaturise linacs by using the v/sub p/xB effect and schemes proposed here
An Arbitrated Quantum Signature Scheme without Entanglement"*
International Nuclear Information System (INIS)
Li Hui-Ran; Luo Ming-Xing; Peng Dai-Yuan; Wang Xiao-Jun
2017-01-01
Several quantum signature schemes are recently proposed to realize secure signatures of quantum or classical messages. Arbitrated quantum signature as one nontrivial scheme has attracted great interests because of its usefulness and efficiency. Unfortunately, previous schemes cannot against Trojan horse attack and DoS attack and lack of the unforgeability and the non-repudiation. In this paper, we propose an improved arbitrated quantum signature to address these secure issues with the honesty arbitrator. Our scheme takes use of qubit states not entanglements. More importantly, the qubit scheme can achieve the unforgeability and the non-repudiation. Our scheme is also secure for other known quantum attacks . (paper)
An Arbitrated Quantum Signature Scheme without Entanglement*
Li, Hui-Ran; Luo, Ming-Xing; Peng, Dai-Yuan; Wang, Xiao-Jun
2017-09-01
Several quantum signature schemes are recently proposed to realize secure signatures of quantum or classical messages. Arbitrated quantum signature as one nontrivial scheme has attracted great interests because of its usefulness and efficiency. Unfortunately, previous schemes cannot against Trojan horse attack and DoS attack and lack of the unforgeability and the non-repudiation. In this paper, we propose an improved arbitrated quantum signature to address these secure issues with the honesty arbitrator. Our scheme takes use of qubit states not entanglements. More importantly, the qubit scheme can achieve the unforgeability and the non-repudiation. Our scheme is also secure for other known quantum attacks.
Analogical Argument Schemes and Complex Argument Structure
Directory of Open Access Journals (Sweden)
Andre Juthe
2015-09-01
Full Text Available This paper addresses several issues in argumentation theory. The over-arching goal is to discuss how a theory of analogical argument schemes fits the pragma-dialectical theory of argument schemes and argument structures, and how one should properly reconstruct both single and complex argumentation by analogy. I also propose a unified model that explains how formal valid deductive argumentation relates to argument schemes in general and to analogical argument schemes in particular. The model suggests “scheme-specific-validity” i.e. that there are contrasting species of validity for each type of argument scheme that derive from one generic conception of validity.
Fractional Poisson Fields and Martingales
Aletti, Giacomo; Leonenko, Nikolai; Merzbach, Ely
2018-01-01
We present new properties for the Fractional Poisson process (FPP) and the Fractional Poisson field on the plane. A martingale characterization for FPPs is given. We extend this result to Fractional Poisson fields, obtaining some other characterizations. The fractional differential equations are studied. We consider a more general Mixed-Fractional Poisson process and show that this process is the stochastic solution of a system of fractional differential-difference equations. Finally, we give some simulations of the Fractional Poisson field on the plane.
Fractional Poisson Fields and Martingales
Aletti, Giacomo; Leonenko, Nikolai; Merzbach, Ely
2018-02-01
We present new properties for the Fractional Poisson process (FPP) and the Fractional Poisson field on the plane. A martingale characterization for FPPs is given. We extend this result to Fractional Poisson fields, obtaining some other characterizations. The fractional differential equations are studied. We consider a more general Mixed-Fractional Poisson process and show that this process is the stochastic solution of a system of fractional differential-difference equations. Finally, we give some simulations of the Fractional Poisson field on the plane.
-Dimensional Fractional Lagrange's Inversion Theorem
Directory of Open Access Journals (Sweden)
F. A. Abd El-Salam
2013-01-01
Full Text Available Using Riemann-Liouville fractional differential operator, a fractional extension of the Lagrange inversion theorem and related formulas are developed. The required basic definitions, lemmas, and theorems in the fractional calculus are presented. A fractional form of Lagrange's expansion for one implicitly defined independent variable is obtained. Then, a fractional version of Lagrange's expansion in more than one unknown function is generalized. For extending the treatment in higher dimensions, some relevant vectors and tensors definitions and notations are presented. A fractional Taylor expansion of a function of -dimensional polyadics is derived. A fractional -dimensional Lagrange inversion theorem is proved.
Metal Borohydrides synthesized from metal borides and metal hydrides
DEFF Research Database (Denmark)
Sommer, Sanna
2014-01-01
Metal Borohydrides Synthesized from Metal Borides and Metal Hydrides Alexander Fogha, Sanna Sommera, Kasper T. Møllera, T. R. Jensena aCenter for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO) and Chemistry Department, Aarhus University, Langelandsgade 140, DK-8000...... Aarhus C, Denmark email: gallafogh@hotmail.com / sanna-sommer@hotmail.com Magnesium boride, MgB2, ball milled with MH (M = Li, Na, Ca) followed by hydrogenation under high hydrogen pressure, readily forms the corresponding metal borohydrides, M(BH4)x (M = Li, Na, Ca) and MgH2 according to reaction scheme...... and Ca(BH4)2, respectively [3,4]. An attempt to synthesize alkali and alkaline earth metal borohydrides from various borides by ball milling under high hydrogen pressure is presented here. MgB2, AlB2 and CaB6 have been milled with MHx (M = Li, Na, Mg, Ca) at p(H2) = 110 bar for 24 hours. All samples were...
Innovative ICF scheme-impact fast ignition
International Nuclear Information System (INIS)
Murakami, M.; Nagatomo, H.; Sakaiya, T.; Karasik, M.; Gardner, J.; Bates, J.
2007-01-01
A totally new ignition scheme for ICF, impact fast ignition (IFI), is proposed [1], in which the compressed DT main fuel is to be ignited by impact collision of another fraction of separately imploded DT fuel, which is accelerated in the hollow conical target. Two-dimensional hydrodynamic simulation results in full geometry are presented, in which some key physical parameters for the impact shell dynamics such as 10 8 cm/s of the implosion velocity, 200- 300 g/cm 3 of the compressed density, and the converted temperature beyond 5 keV are demonstrated. As the first step toward the proof-of-principle of IFI, we have conducted preliminary experiments under the operation of GEKKO XII/HYPER laser system to achieve a hyper-velocity of the order of 108 cm/s. As a result we have observed a highest velocity, 6.5 x 10 7 cm/s, ever achieved. Furthermore, we have also done the first integrated experiments using the target and observed substantial amount of neutron yields. Reference: [1] M. Murakami and Nagatomo, Nucl. Instrum. Meth. Phys. Res. A 544(2005) 67
Gauge invariant fractional electromagnetic fields
Energy Technology Data Exchange (ETDEWEB)
Lazo, Matheus Jatkoske, E-mail: matheuslazo@furg.br [Instituto de Matematica, Estatistica e Fisica - FURG, Rio Grande, RS (Brazil)
2011-09-26
Fractional derivatives and integrations of non-integers orders was introduced more than three centuries ago but only recently gained more attention due to its application on nonlocal phenomenas. In this context, several formulations of fractional electromagnetic fields was proposed, but all these theories suffer from the absence of an effective fractional vector calculus, and in general are non-causal or spatially asymmetric. In order to deal with these difficulties, we propose a spatially symmetric and causal gauge invariant fractional electromagnetic field from a Lagrangian formulation. From our fractional Maxwell's fields arose a definition for the fractional gradient, divergent and curl operators. -- Highlights: → We propose a fractional Lagrangian formulation for fractional Maxwell's fields. → We obtain gauge invariant fractional electromagnetic fields. → Our generalized fractional Maxwell's field is spatially symmetrical. → We discuss the non-causality of the theory.
Fractionalization and Entrepreneurial Activities
Awaworyi Churchill, Sefa
2015-01-01
The vast majority of the literature on ethnicity and entrepreneurship focuses on the construct of ethnic entrepreneurship. However, very little is known about how ethnic heterogeneity affects entrepreneurship. This study attempts to fill the gap, and thus examines the effect of ethnic heterogeneity on entrepreneurial activities in a cross-section of 90 countries. Using indices of ethnic and linguistic fractionalization, we show that ethnic heterogeneity negatively influences entrepreneurship....
DEFF Research Database (Denmark)
Ulrich, Michael; Overgaard, Søren; Penny, Jeannette
2014-01-01
In Denmark 4,456 metal-on-metal (MoM) hip prostheses have been implanted. Evidence demonstrates that some patients develope adverse biological reactions causing failures of MoM hip arthroplasty. Some reactions might be systemic. Failure rates are associated with the type and the design of the Mo...
Decoupling schemes for the SSC Collider
International Nuclear Information System (INIS)
Cai, Y.; Bourianoff, G.; Cole, B.; Meinke, R.; Peterson, J.; Pilat, F.; Stampke, S.; Syphers, M.; Talman, R.
1993-05-01
A decoupling system is designed for the SSC Collider. This system can accommodate three decoupling schemes by using 44 skew quadrupoles in the different configurations. Several decoupling schemes are studied and compared in this paper
Decoupling schemes for the SCC Collider
International Nuclear Information System (INIS)
Cai, Y.; Bourianoff, G.; Cole, B.; Meinke, R.; Peterson, J.; Pilat, F.; Stampke, S.; Syphers, M.; Talman, R.
1993-01-01
A decoupling system is designed for the SSC Collider. This system can accommodate three decoupling schemes by using 44 skew quadrupoles in the different configurations. Several decoupling schemes are studied and compared in this paper
TVD schemes for open channel flow
Delis, A. I.; Skeels, C. P.
1998-04-01
The Saint Venant equations for modelling flow in open channels are solved in this paper, using a variety of total variation diminishing (TVD) schemes. The performance of second- and third-order-accurate TVD schemes is investigated for the computation of free-surface flows, in predicting dam-breaks and extreme flow conditions created by the river bed topography. Convergence of the schemes is quantified by comparing error norms between subsequent iterations. Automatically calculated time steps and entropy corrections allow high CFL numbers and smooth transition between different conditions. In order to compare different approaches with TVD schemes, the most accurate of each type was chosen. All four schemes chosen proved acceptably accurate. However, there are important differences between the schemes in the occurrence of clipping, overshooting and oscillating behaviour and in the highest CFL numbers allowed by a scheme. These variations in behaviour stem from the different orders and inherent properties of the four schemes.
Algebraic K-theory of generalized schemes
DEFF Research Database (Denmark)
Anevski, Stella Victoria Desiree
Nikolai Durov has developed a generalization of conventional scheme theory in which commutative algebraic monads replace commutative unital rings as the basic algebraic objects. The resulting geometry is expressive enough to encompass conventional scheme theory, tropical algebraic geometry and ge...
Algebraic K-theory of generalized schemes
DEFF Research Database (Denmark)
Anevski, Stella Victoria Desiree
Nikolai Durov has developed a generalization of conventional scheme theory in which commutative algebraic monads replace commutative unital rings as the basic algebraic objects. The resulting geometry is expressive enough to encompass conventional scheme theory, tropical algebraic geometry...
Xing, Yanyuan; Yan, Yubin
2018-03-01
Gao et al. [11] (2014) introduced a numerical scheme to approximate the Caputo fractional derivative with the convergence rate O (k 3 - α), 0 definition of the Caputo fractional derivative, see also Lv and Xu [20] (2016), where k is the time step size. Under the assumption that the solution of the time fractional partial differential equation is sufficiently smooth, Lv and Xu [20] (2016) proved by using energy method that the corresponding numerical method for solving time fractional partial differential equation has the convergence rate O (k 3 - α), 0 time variable t. However, in general the solution of the time fractional partial differential equation has low regularity and in this case the numerical method fails to have the convergence rate O (k 3 - α), 0 time variable t. In this paper, we first obtain a similar approximation scheme to the Riemann-Liouville fractional derivative with the convergence rate O (k 3 - α), 0 time discretization scheme to approximate the time fractional partial differential equation and show by using Laplace transform methods that the time discretization scheme has the convergence rate O (k 3 - α), 0 0 for smooth and nonsmooth data in both homogeneous and inhomogeneous cases. Numerical examples are given to show that the theoretical results are consistent with the numerical results.
Fractional Number Operator and Associated Fractional Diffusion Equations
Rguigui, Hafedh
2018-03-01
In this paper, we study the fractional number operator as an analog of the finite-dimensional fractional Laplacian. An important relation with the Ornstein-Uhlenbeck process is given. Using a semigroup approach, the solution of the Cauchy problem associated to the fractional number operator is presented. By means of the Mittag-Leffler function and the Laplace transform, we give the solution of the Caputo time fractional diffusion equation and Riemann-Liouville time fractional diffusion equation in infinite dimensions associated to the fractional number operator.
MIRD radionuclide data and decay schemes
Eckerman, Keith F
2007-01-01
For all physicians, scientists, and physicists working in the nuclear medicine field, the MIRD: Radionuclide Data and Decay Schemes updated edition is an essential sourcebook for radiation dosimetry and understanding the properties of radionuclides. Includes CD Table of Contents Decay schemes listed by atomic number Radioactive decay processes Serial decay schemes Decay schemes and decay tables This essential reference for nuclear medicine physicians, scientists and physicists also includes a CD with tabulations of the radionuclide data necessary for dosimetry calculations.
Secret Sharing Schemes and Advanced Encryption Standard
2015-09-01
Secret Sharing Scheme, they have only been better under certain parameters; there is always a trade -off with some parameter of the scheme. xiv...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS SECRET SHARING SCHEMES AND ADVANCED ENCRYPTION STANDARD by Bing Yong Lim September 2015 Thesis...AND SUBTITLE SECRET SHARING SCHEMES AND ADVANCED ENCRYPTION STANDARD 5. FUNDING NUMBERS 6. AUTHOR(S) Lim, Bin Yong 7. PERFORMING ORGANIZATION NAME(S
Tightly Secure Signatures From Lossy Identification Schemes
Abdalla , Michel; Fouque , Pierre-Alain; Lyubashevsky , Vadim; Tibouchi , Mehdi
2015-01-01
International audience; In this paper, we present three digital signature schemes with tight security reductions in the random oracle model. Our first signature scheme is a particularly efficient version of the short exponent discrete log-based scheme of Girault et al. (J Cryptol 19(4):463–487, 2006). Our scheme has a tight reduction to the decisional short discrete logarithm problem, while still maintaining the non-tight reduction to the computational version of the problem upon which the or...
Energy Technology Data Exchange (ETDEWEB)
Wiggenraad, R.; Verbeek-de Kanter, A.; Mast, M. [Radiotherapy Centre West, The Hague (Netherlands); Molenaar, R. [Diaconessenhuis, Leiden (Netherlands). Dept. of Neurology; Lycklama a Nijeholt, G. [Medical Centre Haagladen, The Hague (Netherlands). Dept. of Radiology; Vecht, C. [Medical Centre Haagladen, The Hague (Netherlands). Dept. of Neurology; Struikmans, H. [Radiotherapy Centre West, The Hague (Netherlands); Leiden Univ. Medical Centre (Netherlands). Dept. of Radiotherapy; Kal, H.B.
2012-08-15
Purpose: The 1-year local control rates after single-fraction stereotactic radiotherapy (SRT) for brain metastases > 3 cm diameter are less than 70%, but with fractionated SRT (FSRT) higher local control rates have been reported. The purpose of this study was to compare our treatment results with SRT and FSRT for large brain metastases. Materials and methods: In two consecutive periods, 41 patients with 46 brain metastases received SRT with 1 fraction of 15 Gy, while 51 patients with 65 brain metastases received FSRT with 3 fractions of 8 Gy. We included patients with brain metastases with a planning target volume of > 13 cm{sup 3} or metastases in the brainstem. Results: The minimum follow-up of patients still alive was 22 months. Comparing 1 fraction of 15 Gy with 3 fractions of 8 Gy, the 1-year rates of freedom from any local progression (54% and 61%, p = 0.93) and pseudo progression (85% and 75%, p = 0.25) were not significantly different. Overall survival rates were also not different. Conclusion: The 1-year local progression and pseudo progression rates after 1 fraction of 15 Gy or 3 fractions of 8 Gy for large brain metastases and metastases in the brainstem are similar. For better local control rates, FSRT schemes with a higher biological equivalent dose may be necessary. (orig.)
Designing quantum-dot cellular automata circuits using a robust one layer crossover scheme
Directory of Open Access Journals (Sweden)
Sara Hashemi
2014-04-01
Full Text Available Quantum-dot cellular automata (QCA is a novel nanotechnology which is considered as a solution to the scaling problems in complementary metal oxide semiconductor technology. In this Letter, a robust one layer crossover scheme is introduced. It uses only 90° QCA cells and works based on a proper clock assignment. The application of this new scheme is shown in designing a sample QCA circuit. Simulation results demonstrate that using this new scheme, significant improvements in terms of area and complexity can be achieved.
Metallated metal-organic frameworks
Energy Technology Data Exchange (ETDEWEB)
Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.
2017-02-07
Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.
Metallated metal-organic frameworks
Energy Technology Data Exchange (ETDEWEB)
Bury, Wojciech; Farha, Omar K.; Hupp, Joseph T.; Mondloch, Joseph E.
2017-08-22
Porous metal-organic frameworks (MOFs) and metallated porous MOFs are provided. Also provided are methods of metallating porous MOFs using atomic layer deposition and methods of using the metallated MOFs as catalysts and in remediation applications.
THROUGHPUT ANALYSIS OF EXTENDED ARQ SCHEMES
African Journals Online (AJOL)
PUBLICATIONS1
and Wait (SW), Selective Repeat (SR), Stutter. (ST) and Go-Back-N (GBN) (Lin and Costello,. 2003). Combinations of these schemes lead to mixed mode schemes which include the SR-. GBN, SR-ST1 and SR-ST2. In the mixed mode schemes, when a prescribed number of failures occur in the SR mode, the GBN or ST ...
The Original Management Incentive Schemes
Richard T. Holden
2005-01-01
During the 1990s, the structure of pay for top corporate executives shifted markedly as the use of stock options greatly expanded. By the early 2000s, as the dot-com boom ended and the Nasdaq stock index melted down, these modern executive incentive schemes were being sharply questioned on many grounds—for encouraging excessive risk-taking and a short-run orientation, for being an overly costly and inefficient method of providing incentives, and even for tempting managers of firms like Enron,...
The mathematics of Ponzi schemes
Artzrouni, Marc
2009-01-01
A first order linear differential equation is used to describe the dynamics of an investment fund that promises more than it can deliver, also known as a Ponzi scheme. The model is based on a promised, unrealistic interest rate; on the actual, realized nominal interest rate; on the rate at which new deposits are accumulated and on the withdrawal rate. Conditions on these parameters are given for the fund to be solvent or to collapse. The model is fitted to data available on Charles...
Adaptive Optics Metrics & QC Scheme
Girard, Julien H.
2017-09-01
"There are many Adaptive Optics (AO) fed instruments on Paranal and more to come. To monitor their performances and assess the quality of the scientific data, we have developed a scheme and a set of tools and metrics adapted to each flavour of AO and each data product. Our decisions to repeat observations or not depends heavily on this immediate quality control "zero" (QC0). Atmospheric parameters monitoring can also help predict performances . At the end of the chain, the user must be able to find the data that correspond to his/her needs. In Particular, we address the special case of SPHERE."
Network Regulation and Support Schemes
DEFF Research Database (Denmark)
Ropenus, Stephanie; Schröder, Sascha Thorsten; Jacobsen, Henrik
2009-01-01
At present, there exists no explicit European policy framework on distributed generation. Various Directives encompass distributed generation; inherently, their implementation is to the discretion of the Member States. The latter have adopted different kinds of support schemes, ranging from feed-in...... tariffs to market-based quota systems, and network regulation approaches, comprising rate-of-return and incentive regulation. National regulation and the vertical structure of the electricity sector shape the incentives of market agents, notably of distributed generators and network operators...
Numerical simulation of fractional Cable equation of spiny neuronal dendrites
Directory of Open Access Journals (Sweden)
N.H. Sweilam
2014-03-01
Full Text Available In this article, numerical study for the fractional Cable equation which is fundamental equations for modeling neuronal dynamics is introduced by using weighted average of finite difference methods. The stability analysis of the proposed methods is given by a recently proposed procedure similar to the standard John von Neumann stability analysis. A simple and an accurate stability criterion valid for different discretization schemes of the fractional derivative and arbitrary weight factor is introduced and checked numerically. Numerical results, figures, and comparisons have been presented to confirm the theoretical results and efficiency of the proposed method.
Vanadium distribution in oil fractions from Western Kazakhstan
Energy Technology Data Exchange (ETDEWEB)
Bakirova, S.F.; Benkovskiy, V.G.; Kotova, A.V.
1980-01-01
This paper investigates distribution of vanadium and metallic-porphyric compounds in heavy fractions and oil residue from a number of fields in Western Kazakhstan. It is shown that in heavy distillation residues, vanadium is present in quantities that are equal to or somewhat above that of in original petroleums. It examines a gradual increase of concentrations of the metallic-porphyric compounds as boiling temperature of heavy oil residues is increased.
Copper isotope fractionation by desert shrubs
International Nuclear Information System (INIS)
Navarrete, Jesica U.; Viveros, Marian; Ellzey, Joanne T.; Borrok, David M.
2011-01-01
Copper has two naturally occurring stable isotopes of masses 63 and 65 which can undergo mass dependent fractionation during various biotic and abiotic chemical reactions. These interactions and their resulting Cu isotope fractionations can be used to determine the mechanisms involved in the cycling of Cu in natural systems. In this study, Cu isotope changes were investigated at the organismal level in the metal-accumulating desert plant, Prosopis pubescens. Initial results suggest that the lighter Cu isotope was preferentially incorporated into the leaves of the plant, which may suggest that Cu was actively transported via intracellular proteins. The roots and stems show a smaller degree of Cu isotope fractionation and the direction and magnitude of the fractionations was dependent upon the levels of Cu exposure. Based on this and previous work with bacteria and yeast, a trend is emerging that suggests the lighter Cu isotope is preferentially incorporated into biological components, while the heavier Cu isotope tends to become enriched in aqueous solutions. In bacteria, plants and animals, intracellular Cu concentrations are strictly regulated via dozens of enzymes that can bind, transport, and store Cu. Many of these enzymes reduce Cu(II) to Cu(I). These initial results seem to fit into a broader picture of Cu isotope cycling in natural systems where oxidation/reduction reactions are fundamental in controlling the distributions of Cu isotopes.
Nuclear Reactor Component Code CUPID-I: Numerical Scheme and Preliminary Assessment Results
Energy Technology Data Exchange (ETDEWEB)
Cho, Hyoung Kyu; Jeong, Jae Jun; Park, Ik Kyu; Kim, Jong Tae; Yoon, Han Young
2007-12-15
A component scale thermal hydraulic analysis code, CUPID (Component Unstructured Program for Interfacial Dynamics), is being developed for the analysis of components of a nuclear reactor, such as reactor vessel, steam generator, containment, etc. It adopted three-dimensional, transient, two phase and three-field model. In order to develop the numerical schemes for the three-field model, various numerical schemes have been examined including the SMAC, semi-implicit ICE, SIMPLE, Row Scheme and so on. Among them, the ICE scheme for the three-field model was presented in the present report. The CUPID code is utilizing unstructured mesh for the simulation of complicated geometries of the nuclear reactor components. The conventional ICE scheme that was applied to RELAP5 and COBRA-TF, therefore, were modified for the application to the unstructured mesh. Preliminary calculations for the unstructured semi-implicit ICE scheme have been conducted for a verification of the numerical method from a qualitative point of view. The preliminary calculation results showed that the present numerical scheme is robust and efficient for the prediction of phase changes and flow transitions due to a boiling and a flashing. These calculation results also showed the strong coupling between the pressure and void fraction changes. Thus, it is believed that the semi-implicit ICE scheme can be utilized for transient two-phase flows in a component of a nuclear reactor.
Nuclear Reactor Component Code CUPID-I: Numerical Scheme and Preliminary Assessment Results
International Nuclear Information System (INIS)
Cho, Hyoung Kyu; Jeong, Jae Jun; Park, Ik Kyu; Kim, Jong Tae; Yoon, Han Young
2007-12-01
A component scale thermal hydraulic analysis code, CUPID (Component Unstructured Program for Interfacial Dynamics), is being developed for the analysis of components of a nuclear reactor, such as reactor vessel, steam generator, containment, etc. It adopted three-dimensional, transient, two phase and three-field model. In order to develop the numerical schemes for the three-field model, various numerical schemes have been examined including the SMAC, semi-implicit ICE, SIMPLE, Row Scheme and so on. Among them, the ICE scheme for the three-field model was presented in the present report. The CUPID code is utilizing unstructured mesh for the simulation of complicated geometries of the nuclear reactor components. The conventional ICE scheme that was applied to RELAP5 and COBRA-TF, therefore, were modified for the application to the unstructured mesh. Preliminary calculations for the unstructured semi-implicit ICE scheme have been conducted for a verification of the numerical method from a qualitative point of view. The preliminary calculation results showed that the present numerical scheme is robust and efficient for the prediction of phase changes and flow transitions due to a boiling and a flashing. These calculation results also showed the strong coupling between the pressure and void fraction changes. Thus, it is believed that the semi-implicit ICE scheme can be utilized for transient two-phase flows in a component of a nuclear reactor
Directory of Open Access Journals (Sweden)
N. Regnault
2011-12-01
Full Text Available Chern insulators are band insulators exhibiting a nonzero Hall conductance but preserving the lattice translational symmetry. We conclusively show that a partially filled Chern insulator at 1/3 filling exhibits a fractional quantum Hall effect and rule out charge-density-wave states that have not been ruled out by previous studies. By diagonalizing the Hubbard interaction in the flat-band limit of these insulators, we show the following: The system is incompressible and has a 3-fold degenerate ground state whose momenta can be computed by postulating an generalized Pauli principle with no more than 1 particle in 3 consecutive orbitals. The ground-state density is constant, and equal to 1/3 in momentum space. Excitations of the system are fractional-statistics particles whose total counting matches that of quasiholes in the Laughlin state based on the same generalized Pauli principle. The entanglement spectrum of the state has a clear entanglement gap which seems to remain finite in the thermodynamic limit. The levels below the gap exhibit counting identical to that of Laughlin 1/3 quasiholes. Both the 3 ground states and excited states exhibit spectral flow upon flux insertion. All the properties above disappear in the trivial state of the insulator—both the many-body energy gap and the entanglement gap close at the phase transition when the single-particle Hamiltonian goes from topologically nontrivial to topologically trivial. These facts clearly show that fractional many-body states are possible in topological insulators.
REMINDER: Saved Leave Scheme (SLS)
2003-01-01
Transfer of leave to saved leave accounts Under the provisions of the voluntary saved leave scheme (SLS), a maximum total of 10 days'* annual and compensatory leave (excluding saved leave accumulated in accordance with the provisions of Administrative Circular No 22B) can be transferred to the saved leave account at the end of the leave year (30 September). We remind you that unused leave of all those taking part in the saved leave scheme at the closure of the leave year accounts is transferred automatically to the saved leave account on that date. Therefore, staff members have no administrative steps to take. In addition, the transfer, which eliminates the risk of omitting to request leave transfers and rules out calculation errors in transfer requests, will be clearly shown in the list of leave transactions that can be consulted in EDH from October 2003 onwards. Furthermore, this automatic leave transfer optimizes staff members' chances of benefiting from a saved leave bonus provided that they ar...
Head-to-Head Comparison of Serum Fractionation Techniques
Energy Technology Data Exchange (ETDEWEB)
Whiteaker, Jeffrey R.; Zhang, Heidi; Eng, Jimmy K.; Fang, Ruihua; Piening, Brian D.; Feng, Li-Chia; lorentzen, Travis D.; Schoenherr, Regine M.; Keane, John F.; Holzman, Ted; Fitzgibbon, Matthew; Lin, Chen Wei; Zhang, Hui; Cooke, Kelly; Liu, Tao; Camp, David G.; Anderson, Leigh N.; Watts, Julian; Smith, Richard D.; McIntosh, Martin; Paulovich, Amanda G.
2007-02-01
Multiple approaches for simplifying the serum proteome have been described. These techniques are generally developed across different laboratories, samples, mass spectrometry platforms, and analysis tools. Hence, comparing the available schemes is impossible from the existing literature because of confounding variables. We describe a head-to-head comparison of several serum fractionation schemes, including N-linked glycopeptide enrichment, cysteinyl-peptide enrichment, magnetic bead separation (C3, C8, and WCX), size fractionation, Protein A/G depletion, and immunoaffinity column depletion of abundant serum proteins. Each technique was compared to results obtained from unfractionated human serum. The results show immunoaffinity subtraction is the most effective means for simplifying the serum proteome and maintaining reasonable sample throughput. The reported dataset is publicly available and provides a standard against which emergent technologies can be compared and evaluated for their contribution to serum-based biomarker discovery.
Fractional channel multichannel analyzer
Brackenbush, L.W.; Anderson, G.A.
1994-08-23
A multichannel analyzer incorporating the features of the present invention obtains the effect of fractional channels thus greatly reducing the number of actual channels necessary to record complex line spectra. This is accomplished by using an analog-to-digital converter in the asynchronous mode, i.e., the gate pulse from the pulse height-to-pulse width converter is not synchronized with the signal from a clock oscillator. This saves power and reduces the number of components required on the board to achieve the effect of radically expanding the number of channels without changing the circuit board. 9 figs.
Andreasen, Niels; Bjerregaard, Mads; Lund, Jonas; Olsen, Ove Bitsch; Rasmussen, Andreas Dalgas
2012-01-01
Projektet er bygget op omkring kritisk realisme, som er det gennemgående videnskabelige fundament til undersøgelsen af hvilke strukturelle grunde der er til finansiel ustabilitet i Danmark. Projektet går i dybden med Fractional Reserve Banking og incitamentsstrukturen i banksystemet. Vi bevæger os både på det makro- og mikroøkonomiske niveau i analysen. På makro niveau bruger vi den østrigske skole om konjunktur teori (The Positive Theory of the Cycle). På mikro niveau arbejder vi med princip...
Analysis of the Properties of Current Penalty Schemes for Violations of Antitrust Law
Motchenkova, E.; Kort, P.M.
2004-01-01
The main feature of the penalty schemes described in current sentencing guidelines is that the fine is based on the accumulated gains from cartel or price-fixing activities for the firm.These gains are usually difficult to estimate, but they can be approximated by a fraction of the turnover.The
Fractional Integral Inequalities via Hadamard’s Fractional Integral
Sudsutad, Weerawat; Ntouyas, Sotiris K.; Tariboon, Jessada
2014-01-01
We establish new fractional integral inequalities, via Hadamard’s fractional integral. Several new integral inequalities are obtained, including a Grüss type Hadamard fractional integral inequality, by using Young and weighted AM-GM inequalities. Many special cases are also discussed.
Fractional Integral Inequalities via Hadamard’s Fractional Integral
Directory of Open Access Journals (Sweden)
Weerawat Sudsutad
2014-01-01
Full Text Available We establish new fractional integral inequalities, via Hadamard’s fractional integral. Several new integral inequalities are obtained, including a Grüss type Hadamard fractional integral inequality, by using Young and weighted AM-GM inequalities. Many special cases are also discussed.
Arbitrated quantum signature scheme using Bell states
International Nuclear Information System (INIS)
Li Qin; Chan, W. H.; Long Dongyang
2009-01-01
In an arbitrated quantum signature scheme, the signatory signs the message and the receiver verifies the signature's validity with the assistance of the arbitrator. We present an arbitrated quantum signature scheme using two-particle entangled Bell states similar to the previous scheme using three-particle entangled Greenberger-Horne-Zeilinger states [G. H. Zeng and C. H. Keitel, Phys. Rev. A 65, 042312 (2002)]. The proposed scheme can preserve the merits in the original scheme while providing a higher efficiency in transmission and reducing the complexity of implementation.
Use of Monomer Fraction Data in the Parametrization of Association Theories
DEFF Research Database (Denmark)
Kontogeorgis, Georgios; Tsivintzelis, Ioannis; von Solms, Nicolas
2010-01-01
the monomer fraction of hydrogen bonding compounds and their mixtures. Monomer fraction data are obtained from spectroscopic measurements and they are available for a few compounds such as pure water and alcohols as well as for some alcohol–alkane and similar mixtures. These data are useful...... “improved” model parameters can be obtained if monomer fraction data are included in the parameter estimation together with vapor pressures and liquid densities. The expression “improved” implies parameters which can represent several pure compound properties as well as monomer fraction data for pure......, liquid densities and monomer fractions of water and alcohols. The 4C scheme is the best choice for water, while for methanol there is small difference between the 2B and 3B association schemes....
On the welfare properties of fractional reserve banking
Sanches, Daniel R.
2015-01-01
Supersedes Working Paper 13-32/R. Monetary economists have long recognized a tension between the benefits of fractional reserve banking, such as the ability to undertake more profitable (long-term) investment opportunities, and the difficulties associated with it, such as the risk of in-solvency for each bank and the associated losses to bank liability holders. I show that a specific banking arrangement (a joint-liability scheme) provides an effective mechanism for ensuring the ex-post transf...
Fractional variational principles with delay
International Nuclear Information System (INIS)
Baleanu, Dumitru; Abdeljawad, Thabet Maaraba; Jarad, Fahd
2008-01-01
The fractional variational principles within Riemann-Liouville fractional derivatives in the presence of delay are analyzed. The corresponding Euler-Lagrange equations are obtained and one example is analyzed in detail
Advances in robust fractional control
Padula, Fabrizio
2015-01-01
This monograph presents design methodologies for (robust) fractional control systems. It shows the reader how to take advantage of the superior flexibility of fractional control systems compared with integer-order systems in achieving more challenging control requirements. There is a high degree of current interest in fractional systems and fractional control arising from both academia and industry and readers from both milieux are catered to in the text. Different design approaches having in common a trade-off between robustness and performance of the control system are considered explicitly. The text generalizes methodologies, techniques and theoretical results that have been successfully applied in classical (integer) control to the fractional case. The first part of Advances in Robust Fractional Control is the more industrially-oriented. It focuses on the design of fractional controllers for integer processes. In particular, it considers fractional-order proportional-integral-derivative controllers, becau...
DEFF Research Database (Denmark)
Ulrich, Michael; Overgaard, Søren; Penny, Jeannette
2014-01-01
In Denmark 4,456 metal-on-metal (MoM) hip prostheses have been implanted. Evidence demonstrates that some patients develope adverse biological reactions causing failures of MoM hip arthroplasty. Some reactions might be systemic. Failure rates are associated with the type and the design of the Mo......M hip implant. A Danish surveillance programme has been initiated addressing these problems....
Heavy metal pollution status in surface sediments of the coastal Bohai Bay.
Gao, Xuelu; Chen, Chen-Tung Arthur
2012-04-15
Bohai Bay, the second largest bay of Bohai Sea, largely due to the huge amount of pollutants discharged into it annually and its geohydrologic condition, is considered to be one of the most polluted marine areas in China. To slow down, halt and finally reverse the environmental deterioration of Bohai Sea, some researchers have proposed to connect it with Jiaozhou Bay in the western coast of Southern Yellow Sea by digging an interbasin canal through Shandong Peninsula. In order to assess the heavy metal pollution and provide background information for such a large geoengineering scheme, surface sediments from 42 stations covering both riverine and marine regions of the northwestern coast of Bohai Bay were analyzed for heavy metal content and fractionation (Cd, Cr, Cu, Ni, Pb and Zn). Three empirically derived sediment quality guidelines were used to assess the pollution extent of these metals. The studied metals had low mobility except for Cd at all stations and Zn at some riverine stations. Although a high mobility of Cd was observed, it could hardly cause a bad effect on the environment owing to its low total concentrations. Anthropogenic influence on the accumulation of studied heavy metals in sediments of Bohai Bay was obvious, but their contents were relatively lower to date comparing with some other marine coastal areas that receive important anthropogenic inputs. Taking as a whole, surface sediments of northwestern Bohai Bay had a 21% probability of toxicity based on the mean effects range-median quotient. Copyright Â© 2012. Published by Elsevier Ltd.
Fractional Reserve in Banking System
Valkonen, Maria
2016-01-01
This thesis is aimed to provide understanding of the role of the fractional reserve in the mod-ern banking system worldwide and particularly in Finland. The fractional reserve banking is used worldwide, but the benefits of this system are very disputable. On the one hand, experts say that the fractional reserve is a necessary instrument for the normal business and profit making. On the other hand, sceptics openly criticize the fractional reserve system and blame it for fiat money (money n...
Fractional Hopfield Neural Networks: Fractional Dynamic Associative Recurrent Neural Networks.
Pu, Yi-Fei; Yi, Zhang; Zhou, Ji-Liu
2017-10-01
This paper mainly discusses a novel conceptual framework: fractional Hopfield neural networks (FHNN). As is commonly known, fractional calculus has been incorporated into artificial neural networks, mainly because of its long-term memory and nonlocality. Some researchers have made interesting attempts at fractional neural networks and gained competitive advantages over integer-order neural networks. Therefore, it is naturally makes one ponder how to generalize the first-order Hopfield neural networks to the fractional-order ones, and how to implement FHNN by means of fractional calculus. We propose to introduce a novel mathematical method: fractional calculus to implement FHNN. First, we implement fractor in the form of an analog circuit. Second, we implement FHNN by utilizing fractor and the fractional steepest descent approach, construct its Lyapunov function, and further analyze its attractors. Third, we perform experiments to analyze the stability and convergence of FHNN, and further discuss its applications to the defense against chip cloning attacks for anticounterfeiting. The main contribution of our work is to propose FHNN in the form of an analog circuit by utilizing a fractor and the fractional steepest descent approach, construct its Lyapunov function, prove its Lyapunov stability, analyze its attractors, and apply FHNN to the defense against chip cloning attacks for anticounterfeiting. A significant advantage of FHNN is that its attractors essentially relate to the neuron's fractional order. FHNN possesses the fractional-order-stability and fractional-order-sensitivity characteristics.
Do Children Understand Fraction Addition?
Braithwaite, David W.; Tian, Jing; Siegler, Robert S.
2017-01-01
Many children fail to master fraction arithmetic even after years of instruction. A recent theory of fraction arithmetic (Braithwaite, Pyke, & Siegler, in press) hypothesized that this poor learning of fraction arithmetic procedures reflects poor conceptual understanding of them. To test this hypothesis, we performed three experiments…
Fractional dynamic calculus and fractional dynamic equations on time scales
Georgiev, Svetlin G
2018-01-01
Pedagogically organized, this monograph introduces fractional calculus and fractional dynamic equations on time scales in relation to mathematical physics applications and problems. Beginning with the definitions of forward and backward jump operators, the book builds from Stefan Hilger’s basic theories on time scales and examines recent developments within the field of fractional calculus and fractional equations. Useful tools are provided for solving differential and integral equations as well as various problems involving special functions of mathematical physics and their extensions and generalizations in one and more variables. Much discussion is devoted to Riemann-Liouville fractional dynamic equations and Caputo fractional dynamic equations. Intended for use in the field and designed for students without an extensive mathematical background, this book is suitable for graduate courses and researchers looking for an introduction to fractional dynamic calculus and equations on time scales. .
Radionuclide fractionation in a forest soil profile
International Nuclear Information System (INIS)
Rigol, A.; Vidal, M.; Rauret, G.
1996-01-01
Two alternative approaches, a sequential extraction scheme and the calculation of the variation of the distribution coefficient of radiocaesium in different K-Ca N H 4 scenarios, were used to study the behaviour and fractionation of this radionuclide in a forest soil profile. The first approach was applied to samples originating from an experiment in which the original L(litter) layer was replaced by an L layer contaminated with a radioactive aerosol, allowing a downward migration of radiocaesium. The samples belonged to different stages after the contamination. The second approach was applied to samples contaminated with soluble radiocaesium. The results indicate that the mineral matter seems to govern the behaviour of radiocaesium in case of direct condensed deposition or when radiocaesium is released from structural components of the organic matter phase. (author). 16 refs., 2 figs., 1 tab
Metal artifact reduction method using metal streaks image subtraction
International Nuclear Information System (INIS)
Pua, Rizza D.; Cho, Seung Ryong
2014-01-01
Many studies have been dedicated for metal artifact reduction (MAR); however, the methods are successful to varying degrees depending on situations. Sinogram in-painting, filtering, iterative method are some of the major categories of MAR. Each has its own merits and weaknesses. A combination of these methods or hybrid methods have also been developed to make use of the different benefits of two techniques and minimize the unfavorable results. Our method focuses on the in-paitning approach and a hybrid MAR described by Xia et al. Although in-painting scheme is an effective technique in reducing the primary metal artifacts, a major drawback is the reintroduction of new artifacts that can be caused by an inaccurate interpolation process. Furthermore, combining the segmented metal image to the corrected nonmetal image in the final step of a conventional inpainting approach causes an issue of incorrect metal pixel values. Our proposed method begins with a sinogram in-painting approach and ends with an image-based metal artifact reduction scheme. This work provides a simple, yet effective solution for reducing metal artifacts and acquiring the original metal pixel information. The proposed method demonstrated its effectiveness in a simulation setting. The proposed method showed image quality that is comparable to the standard MAR; however, quantitatively more accurate than the standard MAR
Scheme of thinking quantum systems
International Nuclear Information System (INIS)
Yukalov, V I; Sornette, D
2009-01-01
A general approach describing quantum decision procedures is developed. The approach can be applied to quantum information processing, quantum computing, creation of artificial quantum intelligence, as well as to analyzing decision processes of human decision makers. Our basic point is to consider an active quantum system possessing its own strategic state. Processing information by such a system is analogous to the cognitive processes associated to decision making by humans. The algebra of probability operators, associated with the possible options available to the decision maker, plays the role of the algebra of observables in quantum theory of measurements. A scheme is advanced for a practical realization of decision procedures by thinking quantum systems. Such thinking quantum systems can be realized by using spin lattices, systems of magnetic molecules, cold atoms trapped in optical lattices, ensembles of quantum dots, or multilevel atomic systems interacting with electromagnetic field
Support Schemes and Ownership Structures
DEFF Research Database (Denmark)
Ropenus, Stephanie; Schröder, Sascha Thorsten; Costa, Ana
of the ongoing fuel cell based micro‐combined heat and power (mCHP) demonstration projects by addressing the socio‐economic and systems analyses perspectives of a large‐scale promotion scheme of fuel cells. This document constitutes the deliverable of Work Package 1 of the FC4Home project and provides......In recent years, fuel cell based micro‐combined heat and power has received increasing attention due to its potential contribution to energy savings, efficiency gains, customer proximity and flexibility in operation and capacity size. The FC4Home project assesses technical and economic aspects...... previous findings and provides a short “preview” of the quantitative analyses in subsequent Work Packages by giving some food for thought on the way....
Kalis, E.J.J.; Temminghoff, E.J.M.; Town, R.M.; Unsworth, E.R.; Riemsdijk, van W.H.
2008-01-01
Received for publication October 12, 2007. The total metal content of the soil or total metal concentration in the soil solution is not always a good indicator for metal availability to plants. Therefore, several speciation techniques have been developed that measure a defined fraction of the total
A framework for ecological risk assessment of metal mixtures in aquatic systems.
Nys, Charlotte; Van Regenmortel, Tina; Janssen, Colin R; Oorts, Koen; Smolders, Erik; De Schamphelaere, Karel A C
2018-03-01
Although metal mixture toxicity has been studied relatively intensely, there is no general consensus yet on how to incorporate metal mixture toxicity into aquatic risk assessment. We combined existing data on chronic metal mixture toxicity at the species level with species sensitivity distribution (SSD)-based in silico metal mixture risk predictions at the community level for mixtures of Ni, Zn, Cu, Cd, and Pb, to develop a tiered risk assessment scheme for metal mixtures in freshwater. Generally, independent action (IA) predicts chronic metal mixture toxicity at the species level most accurately, whereas concentration addition (CA) is the most conservative model. Mixture effects are noninteractive in 69% (IA) and 44% (CA) and antagonistic in 15% (IA) and 51% (CA) of the experiments, whereas synergisms are only observed in 15% (IA) and 5% (CA) of the experiments. At low effect sizes (∼ 10% mixture effect), CA overestimates metal mixture toxicity at the species level by 1.2-fold (i.e., the mixture interaction factor [MIF]; median). Species, metal presence, or number of metals does not significantly affect the MIF. To predict metal mixture risk at the community level, bioavailability-normalization procedures were combined with CA or IA using SSD techniques in 4 different methods, which were compared using environmental monitoring data of a European river basin (the Dommel, The Netherlands). We found that the simplest method, in which CA is directly applied to the SSD (CA SSD ), is also the most conservative method. The CA SSD has median margins of safety (MoS) of 1.1 and 1.2 respectively for binary mixtures compared with the theoretically more consistent methods of applying CA or IA to the dose-response curve of each species individually prior to estimating the fraction of affected species (CA DRC or IA DRC ). The MoS increases linearly with an increasing number of metals, up to 1.4 and 1.7 for quinary mixtures (median) compared with CA DRC and IA DRC
Membrane Assisted Enzyme Fractionation
DEFF Research Database (Denmark)
Yuan, Linfeng
. In this thesis, separations using crossflow elecro-membrane filtration (EMF) of amino acids, bovine serum albumin (BSA) and industrial enzymes from Novozymes were performed. The main objective of this study was to investigate the technological feasibility of EMF in the application of industrial enzyme...... fractionation, such as removal of a side activity from the main enzyme activity. As a proof-of-concept, amino acids were used as model solution to test the feasibility of EMF in the application of amphoteric molecule separation. A single amino acid was used to illustrate the effect of an electric field...... on the separation performance were very small in the investigated range. The mass transport of each enzyme can be well explained by the Extended-Nernst-Planck equation. Better separation was observed at lower feed concentration, higher solution pH in the investigated range and with a polysulfone (PS) MF membrane...
Thermochemical transformations of anthracite fractions
Energy Technology Data Exchange (ETDEWEB)
Belkina, T.V.; Privalov, V.E.; Stepanenko, atM.A.
1979-08-01
Research on the nature of thermochemical transformations of anthracite fractions and the possibility of increasing their activity and identifying conditions for their use in the electrode pitch process is described. From research done on different anthracite fractions processed at varying temperatures it was concluded that accumulations of condensates from heating anthracite fractions occur significantly slower in comparison with pitch. As a result the electrode pitch process is prolonged. Thermal treatment of an anthracite fraction causes the formation and accumulation of condensates and promotes thermochemical transformations. Lastly, the use of thermally treated anthracite fractions apparently intensifies the electrode pitch process and improves its quality. (16 refs.) (In Russian)
Directory of Open Access Journals (Sweden)
Évio Eduardo Chaves de Melo
2008-02-01
Full Text Available Chelate-assisted phytoextraction of heavy metals is a promising approach to clean up polluted soils. However, the most successful chelants tested so far are synthetic agents that barely degrade in soil, increasing the metal leaching risks. Natural organic acids have been proposed to enhance phytoextraction due to their higher biodegradability, but they can also be a drawback for efficient phytoextraction. This work was carried out to compare the effectiveness of multiple applications of citric and gallic acids on the availability in soil and accumulation of Cd, Pb, Cu, and Zn by velvet bean (Stizolobium aterrimum plants. The organic acids were added as follows: 5 mmol kg-1 in the 28th cultivation day; two doses of 5 mmol kg-1 at the 28th and 31st day; and three applications at the same rate at the 28th, 31st, and 34th day of velvet bean cultivation. Soil samples were sequentially extracted and soil solution metal concentrations assessed. Neither citric acid nor gallic acid was efficient for metals phytoextraction. In general, low molecular weight organic acids (LMWOA application increased the metal concentrations in the water soluble and exchangeable fractions. Zinc and Cu were retained mostly in the organic matter fraction. Zn was remobilized from the organic matter fraction through LMWOA application into the water soluble and exchangeable fractions. LMWOA mobilized Pb and Cu from iron oxides, but such an increase in solubility was not high enough to affect phytoextraction.Fitoextração de metais induzida por quelantes é uma técnica promissora para despoluição de solos. Entretanto, os quelantes mais eficientes são sintéticos e apresentam baixa taxa de biodegradação, o que aumenta o risco de lixiviação de metais. Ácidos orgânicos têm sido propostos para auxiliar na fitoextração, mas a sua rápida degradação pode ser limitante para a eficiência desta técnica. O objetivo do trabalho foi comparar a eficiência de aplica
Synchronization and an application of a novel fractional order King Cobra chaotic system
Energy Technology Data Exchange (ETDEWEB)
Muthukumar, P., E-mail: muthukumardgl@gmail.com; Balasubramaniam, P., E-mail: balugru@gmail.com [Department of Mathematics, Gandhigram Rural Institute‐Deemed University, Gandhigram 624 302, Tamilnadu (India); Ratnavelu, K., E-mail: kuru052001@gmail.com [Faculty of Science, Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)
2014-09-01
In this paper, we design a new three dimensional King Cobra face shaped fractional order chaotic system. The multi-scale synchronization scheme of two fractional order chaotic systems is described. The necessary conditions for the multi-scale synchronization of two identical fractional order King Cobra chaotic systems are derived through feedback control. A new cryptosystem is proposed for an image encryption and decryption by using synchronized fractional order King Cobra chaotic systems with the supports of multiple cryptographic assumptions. The security of the proposed cryptosystem is analyzed by the well known algebraic attacks. Numerical simulations are given to show the effectiveness of the proposed theoretical results.
Toward lattice fractional vector calculus
Tarasov, Vasily E.
2014-09-01
An analog of fractional vector calculus for physical lattice models is suggested. We use an approach based on the models of three-dimensional lattices with long-range inter-particle interactions. The lattice analogs of fractional partial derivatives are represented by kernels of lattice long-range interactions, where the Fourier series transformations of these kernels have a power-law form with respect to wave vector components. In the continuum limit, these lattice partial derivatives give derivatives of non-integer order with respect to coordinates. In the three-dimensional description of the non-local continuum, the fractional differential operators have the form of fractional partial derivatives of the Riesz type. As examples of the applications of the suggested lattice fractional vector calculus, we give lattice models with long-range interactions for the fractional Maxwell equations of non-local continuous media and for the fractional generalization of the Mindlin and Aifantis continuum models of gradient elasticity.
Error Analysis of a Finite Element Method for the Space-Fractional Parabolic Equation
Jin, Bangti
2014-01-01
© 2014 Society for Industrial and Applied Mathematics We consider an initial boundary value problem for a one-dimensional fractional-order parabolic equation with a space fractional derivative of Riemann-Liouville type and order α ∈ (1, 2). We study a spatial semidiscrete scheme using the standard Galerkin finite element method with piecewise linear finite elements, as well as fully discrete schemes based on the backward Euler method and the Crank-Nicolson method. Error estimates in the L2(D)- and Hα/2 (D)-norm are derived for the semidiscrete scheme and in the L2(D)-norm for the fully discrete schemes. These estimates cover both smooth and nonsmooth initial data and are expressed directly in terms of the smoothness of the initial data. Extensive numerical results are presented to illustrate the theoretical results.
International Nuclear Information System (INIS)
Stolyarova, T.V.; Skobel'tsyna, E.S.; Grinberg, S.M.; Kruglikov, I.L.; Korotaev, G.K.; Tepelina, O.M.; Il'ina, T.I.
1982-01-01
The effect of low-molecular fraction of thymus humoral factor on blood formation in mice irradiated at 4 Gy was studied. It is shown that injection of low-molecular fraction of thymus hymoral factor to irradiated animals affects proliferative processes in spleen and bone marrow, however the degree of the effect depends on the injection scheme of the preparation. Application of mathematical planning methods of the experiment enables to analyze various injection schemes of low-molecular fraction of thymus humoral factor on the investigated indices. The optimal scheme of preparation injection is determined: 1st injection with the dose of 10 mkg/kg following 4 hour after irradiation, 2d injection - with the same dose in 7-21 days
On Optimal Designs of Some Censoring Schemes
Directory of Open Access Journals (Sweden)
Dr. Adnan Mohammad Awad
2016-03-01
Full Text Available The main objective of this paper is to explore suitability of some entropy-information measures for introducing a new optimality censoring criterion and to apply it to some censoring schemes from some underlying life-time models. In addition, the paper investigates four related issues namely; the effect of the parameter of parent distribution on optimal scheme, equivalence of schemes based on Shannon and Awad sup-entropy measures, the conjecture that the optimal scheme is one stage scheme, and a conjecture by Cramer and Bagh (2011 about Shannon minimum and maximum schemes when parent distribution is reflected power. Guidelines for designing an optimal censoring plane are reported together with theoretical and numerical results and illustrations.
Tissue engineering scheming by artificial intelligence.
Xu, J; Ge, H; Zhou, X; Yang, D
2005-01-01
Tissue engineers are often confused when seeking the most effective, economical and secure scheme for tissue engineering. The aim of this study is to generate tissue engineering schemes with artificial intelligence instead of human intelligence. The experimental data of tissue engineered cartilage were integrated and standardized with a centralized database, and a scheme engine was developed using artificial intelligent methods (artificial neural networks and decision trees). The scheme engine was trained with existing cases in the database, and then was used to generate tissue engineering schemes for new experimental animals. Following the schemes generated by the artificial intelligent system, we cured 18 of the 20 experimental animals. In conclusion, artificial intelligence is a powerful method for decision making in the tissue engineering realm.
How can conceptual schemes change teaching?
Wickman, Per-Olof
2012-03-01
Lundqvist, Almqvist and Östman describe a teacher's manner of teaching and the possible consequences it may have for students' meaning making. In doing this the article examines a teacher's classroom practice by systematizing the teacher's transactions with the students in terms of certain conceptual schemes, namely the epistemological moves, educational philosophies and the selective traditions of this practice. In connection to their study one may ask how conceptual schemes could change teaching. This article examines how the relationship of the conceptual schemes produced by educational researchers to educational praxis has developed from the middle of the last century to today. The relationship is described as having been transformed in three steps: (1) teacher deficit and social engineering, where conceptual schemes are little acknowledged, (2) reflecting practitioners, where conceptual schemes are mangled through teacher practice to aid the choices of already knowledgeable teachers, and (3) the mangling of the conceptual schemes by researchers through practice with the purpose of revising theory.
Resonance ionization scheme development for europium
Chrysalidis, K; Fedosseev, V N; Marsh, B A; Naubereit, P; Rothe, S; Seiffert, C; Kron, T; Wendt, K
2017-01-01
Odd-parity autoionizing states of europium have been investigated by resonance ionization spectroscopy via two-step, two-resonance excitations. The aim of this work was to establish ionization schemes specifically suited for europium ion beam production using the ISOLDE Resonance Ionization Laser Ion Source (RILIS). 13 new RILIS-compatible ionization schemes are proposed. The scheme development was the first application of the Photo Ionization Spectroscopy Apparatus (PISA) which has recently been integrated into the RILIS setup.
Alternative schemes for the inertial fusion energy
Energy Technology Data Exchange (ETDEWEB)
Tikhonchuk, V.T. [Centre Lasers Intenses et Applications, University Bordeaux 1-CNRS-CEA, 33405, Talence (France); Mima, K., E-mail: tikhonchuk@celia.u-bordeaux1.fr [Institute of Laser Engineering, Osaka University, Osaka (Japan)
2011-10-15
The advanced target designs are requiring a lower laser energy for ignition and promising higher energy gains. Two approaches are under development within the European inertial fusion energy project HiPER: the fast ignition scheme with energetic electrons and the shock ignition scheme. The fundamental physical issues and major experimental works related to the alternative ignition schemes as well as the reactor designs are discussed.
Resonance ionization scheme development for europium
Energy Technology Data Exchange (ETDEWEB)
Chrysalidis, K., E-mail: katerina.chrysalidis@cern.ch; Goodacre, T. Day; Fedosseev, V. N.; Marsh, B. A. [CERN (Switzerland); Naubereit, P. [Johannes Gutenberg-Universität, Institiut für Physik (Germany); Rothe, S.; Seiffert, C. [CERN (Switzerland); Kron, T.; Wendt, K. [Johannes Gutenberg-Universität, Institiut für Physik (Germany)
2017-11-15
Odd-parity autoionizing states of europium have been investigated by resonance ionization spectroscopy via two-step, two-resonance excitations. The aim of this work was to establish ionization schemes specifically suited for europium ion beam production using the ISOLDE Resonance Ionization Laser Ion Source (RILIS). 13 new RILIS-compatible ionization schemes are proposed. The scheme development was the first application of the Photo Ionization Spectroscopy Apparatus (PISA) which has recently been integrated into the RILIS setup.
Data mining for detecting Bitcoin Ponzi schemes
Bartoletti, Massimo; Pes, Barbara; Serusi, Sergio
2018-01-01
Soon after its introduction in 2009, Bitcoin has been adopted by cyber-criminals, which rely on its pseudonymity to implement virtually untraceable scams. One of the typical scams that operate on Bitcoin are the so-called Ponzi schemes. These are fraudulent investments which repay users with the funds invested by new users that join the scheme, and implode when it is no longer possible to find new investments. Despite being illegal in many countries, Ponzi schemes are now proliferating on Bit...
Misonidazole in fractionated radiotherapy: are many small fractions best
International Nuclear Information System (INIS)
Denekamp, J.; McNally, N.J.; Fowler, J.F.; Joiner, M.C.
1980-01-01
The largest sensitizing effect is always demonstrated with six fractions, each given with 2 g/m 2 of misonidazole. In the absence of reoxygenation a sensitizer enhancement ratio of 1.7 is predicted, but this falls to 1.1-1.2 if extensive reoxygenation occurs. Less sensitization is observed with 30 fractions, each with 0.4 g/m 2 of drug. However, for clinical use, the important question is which treatment kills the maximum number of tumour cells. Many of the simulations predict a marked disadvantage of reducing the fraction number for X rays alone. The circumstances in which this disadvantage is offset by the large Sensitizer enhancement ratio values with a six-fraction schedule are few. The model calculations suggest that many small fractions, each with a low drug dose, are safest unless the clinician has some prior knowledge that a change in fraction number is not disadvantageous. (author)
A study on the potential of cell kinetically directed fractionation schemes in radiotherapy
International Nuclear Information System (INIS)
Oostrum, I.E.A. van.
1990-01-01
In this thesis, the phenomenon of radiation-induced synchronization of cells into the radiosensitive G 2 phase of the cell cycle and the exploitation of this phenomenon to enhance the efficacy of frationated radiotherapy was investigated. A nude mouse model was used to investigate the cell kinetics of 6 human xenotransplanted tumours before and after irradiation. In the second part of the investigation it was tested whether split dose irradiation intervals, based on cell kinetic data of the tumours (i.e. timing of maximal accumulation of cells in G 2 ) would result in an enhanced response compared with those at non optimal intervals (author), 297 refs.; 35 figs.; 25 tabs
Characterization Scheme for Property Prediction of Fluid Fractions Originating from Biomass
DEFF Research Database (Denmark)
Nguyen, Thanh-Binh; de Hemptinne, Jean-Charles; Creton, Benoit
2015-01-01
identified and summarized four such approaches, generally based on experimental information such as boiling temperature and density. Fluids that originate from biomass, however, cannot be treated using only volatility, because of the highly polar character and the high molecular weight of its components......) has been constructed, which contains a number of descriptors originating from analytical measurements. Using physical insight on the molecular interactions, an algorithm is proposed that uses five descriptors (molecular weight, liquid molar volume, viscosity, refractive index, and dielectric constant...
A numerical solution for a class of time fractional diffusion equations with delay
Directory of Open Access Journals (Sweden)
Pimenov Vladimir G.
2017-09-01
Full Text Available This paper describes a numerical scheme for a class of fractional diffusion equations with fixed time delay. The study focuses on the uniqueness, convergence and stability of the resulting numerical solution by means of the discrete energy method. The derivation of a linearized difference scheme with convergence order O(τ2−α+ h4 in L∞-norm is the main purpose of this study. Numerical experiments are carried out to support the obtained theoretical results.
The Galerkin Finite Element Method for A Multi-term Time-Fractional Diffusion equation
Jin, Bangti; Lazarov, Raytcho; Liu, Yikan; Zhou, Zhi
2014-01-01
We consider the initial/boundary value problem for a diffusion equation involving multiple time-fractional derivatives on a bounded convex polyhedral domain. We analyze a space semidiscrete scheme based on the standard Galerkin finite element method using continuous piecewise linear functions. Nearly optimal error estimates for both cases of initial data and inhomogeneous term are derived, which cover both smooth and nonsmooth data. Further we develop a fully discrete scheme based on a finite...
Comparing Security Notions of Secret Sharing Schemes
Directory of Open Access Journals (Sweden)
Songsong Dai
2015-03-01
Full Text Available Different security notions of secret sharing schemes have been proposed by different information measures. Entropies, such as Shannon entropy and min entropy, are frequently used in the setting security notions for secret sharing schemes. Different to the entropies, Kolmogorov complexity was also defined and used in study the security of individual instances for secret sharing schemes. This paper is concerned with these security notions for secret sharing schemes defined by the variational measures, including Shannon entropy, guessing probability, min entropy and Kolmogorov complexity.
Quantum signature scheme for known quantum messages
International Nuclear Information System (INIS)
Kim, Taewan; Lee, Hyang-Sook
2015-01-01
When we want to sign a quantum message that we create, we can use arbitrated quantum signature schemes which are possible to sign for not only known quantum messages but also unknown quantum messages. However, since the arbitrated quantum signature schemes need the help of a trusted arbitrator in each verification of the signature, it is known that the schemes are not convenient in practical use. If we consider only known quantum messages such as the above situation, there can exist a quantum signature scheme with more efficient structure. In this paper, we present a new quantum signature scheme for known quantum messages without the help of an arbitrator. Differing from arbitrated quantum signature schemes based on the quantum one-time pad with the symmetric key, since our scheme is based on quantum public-key cryptosystems, the validity of the signature can be verified by a receiver without the help of an arbitrator. Moreover, we show that our scheme provides the functions of quantum message integrity, user authentication and non-repudiation of the origin as in digital signature schemes. (paper)
A Spatial Domain Quantum Watermarking Scheme
International Nuclear Information System (INIS)
Wei Zhan-Hong; Chen Xiu-Bo; Niu Xin-Xin; Yang Yi-Xian; Xu Shu-Jiang
2016-01-01
This paper presents a spatial domain quantum watermarking scheme. For a quantum watermarking scheme, a feasible quantum circuit is a key to achieve it. This paper gives a feasible quantum circuit for the presented scheme. In order to give the quantum circuit, a new quantum multi-control rotation gate, which can be achieved with quantum basic gates, is designed. With this quantum circuit, our scheme can arbitrarily control the embedding position of watermark images on carrier images with the aid of auxiliary qubits. Besides reversely acting the given quantum circuit, the paper gives another watermark extracting algorithm based on quantum measurements. Moreover, this paper also gives a new quantum image scrambling method and its quantum circuit. Differ from other quantum watermarking schemes, all given quantum circuits can be implemented with basic quantum gates. Moreover, the scheme is a spatial domain watermarking scheme, and is not based on any transform algorithm on quantum images. Meanwhile, it can make sure the watermark be secure even though the watermark has been found. With the given quantum circuit, this paper implements simulation experiments for the presented scheme. The experimental result shows that the scheme does well in the visual quality and the embedding capacity. (paper)
Improved Load Shedding Scheme considering Distributed Generation
DEFF Research Database (Denmark)
Das, Kaushik; Nitsas, Antonios; Altin, Müfit
2017-01-01
. These schemes utilize directional relays, power flow through feeders, wind and PV measurements to optimally select the feeders to be disconnected during load shedding such that DG disconnection is minimized while disconnecting required amount of consumption. These different UFLS schemes are compared in terms......With high penetration of distributed generation (DG), the conventional under-frequency load shedding (UFLS) face many challenges and may not perform as expected. This article proposes new UFLS schemes, which are designed to overcome the shortcomings of traditional load shedding scheme...... of frequency response, amount of consumption and DG disconnected during load shedding....
Fractional variational calculus in terms of Riesz fractional derivatives
International Nuclear Information System (INIS)
Agrawal, O P
2007-01-01
This paper presents extensions of traditional calculus of variations for systems containing Riesz fractional derivatives (RFDs). Specifically, we present generalized Euler-Lagrange equations and the transversality conditions for fractional variational problems (FVPs) defined in terms of RFDs. We consider two problems, a simple FVP and an FVP of Lagrange. Results of the first problem are extended to problems containing multiple fractional derivatives, functions and parameters, and to unspecified boundary conditions. For the second problem, we present Lagrange-type multiplier rules. For both problems, we develop the Euler-Lagrange-type necessary conditions which must be satisfied for the given functional to be extremum. Problems are considered to demonstrate applications of the formulations. Explicitly, we introduce fractional momenta, fractional Hamiltonian, fractional Hamilton equations of motion, fractional field theory and fractional optimal control. The formulations presented and the resulting equations are similar to the formulations for FVPs given in Agrawal (2002 J. Math. Anal. Appl. 272 368, 2006 J. Phys. A: Math. Gen. 39 10375) and to those that appear in the field of classical calculus of variations. These formulations are simple and can be extended to other problems in the field of fractional calculus of variations
Directory of Open Access Journals (Sweden)
Ram Verma
2016-02-01
Full Text Available This paper deals with mainly establishing numerous sets of generalized second order paramertic sufficient optimality conditions for a semiinfinite discrete minmax fractional programming problem, while the results on semiinfinite discrete minmax fractional programming problem achieved based on some partitioning schemes under various types of generalized second order univexity assumptions.
Hunt, Jessica Heather; Tzur, Ron; Westenskow, Arla
2016-01-01
The literature seems limited in what is known about conceptual processes that underlie evolution of students with learning disabilities (SLD) conceptions of fractions. This exploratory study examines how a foundational scheme of unit fractions (1/n) may evolve through the mathematical activity of two fifth grade girls. We analyze data segments…
Void fraction measurements using neutron radiography
International Nuclear Information System (INIS)
Glickstein, S.S.; Vance, W.H.; Joo, H.
1992-01-01
Real-time neutron radiography is being evaluated for studying the dynamic behavior of two phase flow and for measuring void fraction in vertical and inclined water ducts. This technique provides a unique means of visualizing the behavior of fluid flow inside thick metal enclosures. To simulate vapor conditions encountered in a fluid flow duct, an air-water flow system was constructed. Air was injected into the bottom of the duct at flow rates up to 0.47 I/s (1 cfm). The water flow rate was varied between 0--3.78 I/m (0--1 gpm). The experiments were performed at the Pennsylvania State University nuclear reactor facility using a real-time neutron radiography camera. With a thermal neutron flux on the order of 10 6 n/cm 2 /s directed through the thin duct dimension, the dynamic behavior of the air bubbles was clearly visible through 5 cm (2 in.) thick aluminum support plates placed on both sides of the duct wall. Image analysis techniques were employed to extract void fractions from the data which was recorded on videotape. This consisted of time averaging 256 video frames and measuring the gray level distribution throughout the region. The distribution of the measured void fraction across the duct was determined for various air/water mixtures. Details of the results of experiments for a variety of air and water flow conditions are presented
Dynamical fractional chaotic inflation
Harigaya, Keisuke; Ibe, Masahiro; Schmitz, Kai; Yanagida, Tsutomu T.
2014-12-01
Chaotic inflation based on a simple monomial scalar potential, V (ϕ )∝ϕp, is an attractive large-field model of inflation capable of generating a sizable tensor-to-scalar ratio r . Therefore, assuming that future cosmic microwave background observations will confirm the large r value reported by BICEP2, it is important to determine what kind of dynamical mechanism could possibly endow the inflaton field with such a simple effective potential. In this paper, we answer this question in the context of field theory, i.e. in the framework of dynamical chaotic inflation, where strongly interacting supersymmetric gauge dynamics around the scale of grand unification dynamically generate a fractional power-law potential via the quantum effect of dimensional transmutation. In constructing explicit models, we significantly extend our previous work, as we now consider a large variety of possible underlying gauge dynamics and relax our conditions on the field content of the model. This allows us to realize almost arbitrary rational values for the power p in the inflaton potential. The present paper may hence be regarded as a first step toward a more complete theory of dynamical chaotic inflation.
Metal speciation under Rhizophora and Avicennia mangles
Andrade, Regina Célia Bastos de; Patchineelam, Sambasiva Rao
2000-01-01
Speciation studies of Fe, Cr, Co, Ni and Cu on reactive fraction (adsorved on oxides, hydroxides, carbonates and clay minerals) and pyrite were performed in Avicennia schaueriana and Rhizophora mangle sediments from Amapá shoreline-Brazil. The soil under Avicennia showed a higher heavy metal concentration in reactive fraction than under Rhizophora. The soil under Rhizophora showed low heavy metal bioavailability, having an increasing association with pyrite across sediment section.
The Galerkin finite element method for a multi-term time-fractional diffusion equation
Jin, Bangti
2015-01-01
© 2014 The Authors. We consider the initial/boundary value problem for a diffusion equation involving multiple time-fractional derivatives on a bounded convex polyhedral domain. We analyze a space semidiscrete scheme based on the standard Galerkin finite element method using continuous piecewise linear functions. Nearly optimal error estimates for both cases of initial data and inhomogeneous term are derived, which cover both smooth and nonsmooth data. Further we develop a fully discrete scheme based on a finite difference discretization of the time-fractional derivatives, and discuss its stability and error estimate. Extensive numerical experiments for one- and two-dimensional problems confirm the theoretical convergence rates.
Accessible solitons of fractional dimension
Energy Technology Data Exchange (ETDEWEB)
Zhong, Wei-Ping, E-mail: zhongwp6@126.com [Department of Electronic and Information Engineering, Shunde Polytechnic, Guangdong Province, Shunde 528300 (China); Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar); Belić, Milivoj [Texas A& M University at Qatar, P.O. Box 23874, Doha (Qatar); Zhang, Yiqi [Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, Xi’an Jiaotong University, Xi’an 710049 (China)
2016-05-15
We demonstrate that accessible solitons described by an extended Schrödinger equation with the Laplacian of fractional dimension can exist in strongly nonlocal nonlinear media. The soliton solutions of the model are constructed by two special functions, the associated Legendre polynomials and the Laguerre polynomials in the fraction-dimensional space. Our results show that these fractional accessible solitons form a soliton family which includes crescent solitons, and asymmetric single-layer and multi-layer necklace solitons. -- Highlights: •Analytic solutions of a fractional Schrödinger equation are obtained. •The solutions are produced by means of self-similar method applied to the fractional Schrödinger equation with parabolic potential. •The fractional accessible solitons form crescent, asymmetric single-layer and multilayer necklace profiles. •The model applies to the propagation of optical pulses in strongly nonlocal nonlinear media.
Fractional Calculus and Shannon Wavelet
Directory of Open Access Journals (Sweden)
Carlo Cattani
2012-01-01
Full Text Available An explicit analytical formula for the any order fractional derivative of Shannon wavelet is given as wavelet series based on connection coefficients. So that for any 2(ℝ function, reconstructed by Shannon wavelets, we can easily define its fractional derivative. The approximation error is explicitly computed, and the wavelet series is compared with Grünwald fractional derivative by focusing on the many advantages of the wavelet method, in terms of rate of convergence.
Directory of Open Access Journals (Sweden)
Salahuddin Asif
2013-01-01
Full Text Available Multiple recycling of actinides and non-volatile fission products in fast reactors through the dry re-fabrication/reprocessing atomics international reduction oxidation process has been studied as a possible way to reduce the long-term potential hazard of nuclear waste compared to that resulting from reprocessing in a wet PUREX process. Calculations have been made to compare the actinides and fission products recycling scheme with the normal plutonium recycling scheme in a fast reactor. For this purpose, the Karlsruhe version of isotope generation and depletion code, KORIGEN, has been modified accordingly. An entirely novel fission product yields library for fast reactors has been created which has replaced the old KORIGEN fission products library. For the purposes of this study, the standard 26 groups data set, KFKINR, developed at Forschungszentrum Karlsruhe, Germany, has been extended by the addition of the cross-sections of 13 important actinides and 68 most important fission products. It has been confirmed that these 68 fission products constitute about 95% of the total fission products yield and about 99.5% of the total absorption due to fission products in fast reactors. The amount of fissile material required to guarantee the criticality of the reactor during recycling schemes has also been investigated. Cumulative high active waste per ton of initial heavy metal is also calculated. Results show that the recycling of actinides and fission products in fast reactors through the atomics international reduction oxidation process results in a reduction of the potential hazard of radioactive waste.
Microporous crystals and synthesis schemes
Tumas, William; Ott, Kevin C.; McCleskey, T. Mark; Yates, Matthew Z.; Birnbaum, Eva R.
2005-09-27
Novel zeolites are produced by combining a polar solute, a silicon or phosphorous source, and a structure directing agent. Surfactants and a hydrophobic solvent are added to the previously mixed three species and shaken to disperse the surfactants. The reverse microemulsion is stirred overnight, at about room temperature and then iced for five to ten minutes. A metal source is added vigorously shaken for about two minutes. The mixture is then aged for about two hours at about room temperature. A mineralizer is added and the resultant mixture aged for about two hours at about room temperature. The mixture is heated to about 180.degree. C., for a suitable time period. The final novel product is then isolated.
Microporous crystals and synthesis schemes
Tumas, William; Ott, Kevin C.; McCleskey, T. Mark; Yates, Matthew Z.; Birnbaum, Eva R.
2008-04-22
Novel zeolites are produced by combining a polar solute, a silicon or phosphorous source, and a structure directing agent. Surfactants and a hydrophobic solvent are added to the previously mixed three species and shaken to disperse the surfactants. The reverse microemulsion is stirred overnight, at about room temperature and then iced for five to ten minutes. A metal source is added vigorously shaken for about two minutes. The mixture is then aged for about two hours at about room temperature. A mineralizer is added and the resultant mixture aged for about two hours at about room temperature. The mixture is heated to about 180.degree. C., for a suitable time period. The final novel product is then isolated.
Directory of Open Access Journals (Sweden)
Meilan Qiu
2017-01-01
Full Text Available We focus on developing the finite difference (i.e., backward Euler difference or second-order central difference/local discontinuous Galerkin finite element mixed method to construct and analyze a kind of efficient, accurate, flexible, numerical schemes for approximately solving time-space fractional subdiffusion/superdiffusion equations. Discretizing the time Caputo fractional derivative by using the backward Euler difference for the derivative parameter (0<α<1 or second-order central difference method for (1<α<2, combined with local discontinuous Galerkin method to approximate the spatial derivative which is defined by a fractional Laplacian operator, two high-accuracy fully discrete local discontinuous Galerkin (LDG schemes of the time-space fractional subdiffusion/superdiffusion equations are proposed, respectively. Through the mathematical induction method, we show the concrete analysis for the stability and the convergence under the L2 norm of the LDG schemes. Several numerical experiments are presented to validate the proposed model and demonstrate the convergence rate of numerical schemes. The numerical experiment results show that the fully discrete local discontinuous Galerkin (LDG methods are efficient and powerful for solving fractional partial differential equations.
Fractional delayed damped Mathieu equation
Mesbahi, Afshin; Haeri, Mohammad; Nazari, Morad; Butcher, Eric A.
2015-03-01
This paper investigates the dynamical behaviour of the fractional delayed damped Mathieu equation. This system includes three different phenomena (fractional order, time delay, parametric resonance). The method of harmonic balance is employed to achieve approximate expressions for the transition curves in the parameter plane. The n = 0 and n = 1 transition curves (both lower and higher order approximations) are obtained. The dependencies of these curves on the system parameters and fractional orders are determined. Previous results for the transition curves reported for the damped Mathieu equation, delayed second-order oscillator, and fractional Mathieu equation are confirmed as special cases of the results for the current system.
Speciation of Heavy Metals in Sediment of Agbabu Bitumen deposit ...
African Journals Online (AJOL)
Speciation of heavy metals Cu, Cd, Pb, Ni, Zn, Mn, Fe, Cr and Hg was carried out on sediment of Agbabu with a sequential extraction procedure in the dry and rainy seasons of year 2008. Hg was not detected in all the fractions in the two seasons. In the dry season, all the metals were mostly abundant in Fraction-5, however ...
Synergetic Effects of Alcohol/Water Mixing on the Catalytic Reductive Fractionation of Poplar Wood
Energy Technology Data Exchange (ETDEWEB)
Renders, Tom; Van den Bosch, Sander; Vangeel, Thijs; Ennaert, Thijs; Koelewijn, Steven-Friso; Van den Bossche, Gil; Courtin, Christophe M.; Schutyser, Wouter; Sels, Bert F.
2016-12-05
One of the foremost challenges in lignocellulose conversion encompasses the integration of effective lignin valorization in current carbohydrate-oriented biorefinery schemes. Catalytic reductive fractionation (CRF) of lignocellulose offers a technology to simultaneously produce lignin-derived platform chemicals and a carbohydrate-enriched pulp via the combined action of lignin solvolysis and metal-catalyzed hydrogenolysis. Herein, the solvent (composition) plays a crucial role. In this contribution, we study the influence of alcohol/water mixtures by processing poplar sawdust in varying MeOH/water and EtOH/water blends. The results show particular effects that strongly depend on the applied water concentration. Low water concentrations enhance the removal of lignin from the biomass, while the majority of the carbohydrates are left untouched (scenario A). Contrarily, high water concentrations favor the solubilization of both hemicellulose and lignin, resulting in a more pure cellulosic residue (scenario B). For both scenarios, an evaluation was made to determine the most optimal solvent composition, based on two earlier introduced empirical efficiency descriptors (denoted LFDE and LFFE). According to these measures, 30 (A) and 70 vol % water (B) showed to be the optimal balance for both MeOH/water and EtOH/water mixtures. This successful implementation of alcohol/water mixtures allows operation under milder processing conditions in comparison to pure alcohol solvents, which is advantageous from an industrial point of view.
TU-H-BRC-02: Biological Dose Escalation for Liver SBRT Through Spatiotemporal Fractionation
Energy Technology Data Exchange (ETDEWEB)
Unkelbach, J; Perko, Z; Wolfgang, J; Hong, T [Massachusetts General Hospital, Boston, MA (United States)
2016-06-15
Purpose: Stereotactic body radiotherapy (SBRT) has become an established treatment option for liver cancer. For patients with large tumors, the prescription dose is often limited by constraints on the mean liver dose, leading to tumor recurrence. In this work, we demonstrate that spatiotemporal fractionation schemes, ie delivering distinct dose distributions in different fractions, may allow for a 10% increase in biologically effective dose (BED) in the tumor compared to current practice where each fraction delivers the same dose distribution. Methods: We consider rotation therapy delivered with x-ray beams. Treatment plan optimization is performed using objective functions evaluated for the cumulative BED delivered at the end of treatment. This allows for simultaneously optimizing multiple distinct treatment plans for different fractions. Results: The treatment that optimally exploits fractionation effects is designed such that each fraction delivers a similar dose bath to the uninvolved liver while delivering high single fraction doses to complementary parts of the target volume. Thereby, partial hypofractionation in the tumor is achieved along with near uniform fractionation in the surrounding liver - leading to an improvement in the therapeutic ratio. The benefit of such spatiotemporal fractionation schemes depends on tumor geometry and location as well as the number of fractions. For 5-fraction treatments (allowing for 5 distinct dose distributions) an improvement in the order of 10% is observed. Conclusion: Delivering distinct dose distributions in different fractions, purely motivated by fractionation effects rather than geometric changes, may improve the therapeutic ratio. For treatment sites where the prescriptions dose is limited by mean dose constraints in the surrounding organ, such as liver cancer, this approach may facilitate biological dose escalation and improved cure rates.
Mobile Machine for E-payment Scheme
Sattar J Aboud
2010-01-01
In this article e-payment scheme by mobile machine is considered. The requirements for a mobile machine in e-payment are presented, particularly when merchant employing accounts for payments and when using advertising. In the proposed scheme we will use the public key infrastructure and certificate for authenticate purchaser and merchant and to secure the communication between them.
Sampling scheme optimization from hyperspectral data
Debba, P.
2006-01-01
This thesis presents statistical sampling scheme optimization for geo-environ-menta] purposes on the basis of hyperspectral data. It integrates derived products of the hyperspectral remote sensing data into individual sampling schemes. Five different issues are being dealt with.First, the optimized
A generalized scheme for designing multistable continuous ...
Indian Academy of Sciences (India)
In this paper, a generalized scheme is proposed for designing multistable continuous dynamical systems. The scheme is based on the concept of partial synchronization of states and the concept of constants of motion. The most important observation is that by coupling two mdimensional dynamical systems, multistable ...
Hybrid scheme for Brownian semistationary processes
DEFF Research Database (Denmark)
Bennedsen, Mikkel; Lunde, Asger; Pakkanen, Mikko S.
We introduce a simulation scheme for Brownian semistationary processes, which is based on discretizing the stochastic integral representation of the process in the time domain. We assume that the kernel function of the process is regularly varying at zero. The novel feature of the scheme is to ap...
Consolidation of the health insurance scheme
Association du personnel
2009-01-01
In the last issue of Echo, we highlighted CERN’s obligation to guarantee a social security scheme for all employees, pensioners and their families. In that issue we talked about the first component: pensions. This time we shall discuss the other component: the CERN Health Insurance Scheme (CHIS).
A hierarchical classification scheme of psoriasis images
DEFF Research Database (Denmark)
Maletti, Gabriela Mariel; Ersbøll, Bjarne Kjær
2003-01-01
A two-stage hierarchical classification scheme of psoriasis lesion images is proposed. These images are basically composed of three classes: normal skin, lesion and background. The scheme combines conventional tools to separate the skin from the background in the first stage, and the lesion from...
Community healthcare financing scheme: findings among residents ...
African Journals Online (AJOL)
... none were active participants as 2(0.6%) were indifferent. There was a statistically significant relationship, Fischers <0.0001 between sex and the scheme's knowledge. Conclusion: Knowledge of the scheme was poor among majority of the respondents and none were active participants. Bribery and corruption was the ...
A generalized scheme for designing multistable continuous ...
Indian Academy of Sciences (India)
Abstract. In this paper, a generalized scheme is proposed for designing multistable continuous dynamical systems. The scheme is based on the concept of partial synchronization of states and the concept of constants of motion. The most important observation is that by coupling two m- dimensional dynamical systems ...
Boonjob, Warunya; Miró, Manuel; Cerdà, Víctor
2008-10-01
There is a current trend in automation of leaching tests for trace elements in solid matrixes by use of flow injection based column approaches. However, as a result of the downscaled dimensions of the analytical manifold and execution of a single extraction at a time, miniaturized flow-through column approaches have merely found applications for periodic investigations of trace element mobility in highly homogeneous environmental solids. A novel flow-based configuration capitalized on stirred-flow cell extraction is proposed in this work for simultaneous fractionation of trace elements in three solid wastes with no limitation of sample amount up to 1.0 g. A two-step sequential extraction scheme involving water and acetic acid (or acetic acid/acetate buffer) is utilized for accurate assessment of readily mobilizable fractions of trace elements in fly ash samples. The fully automated extraction system features high tolerance to flow rates (elements provided that exhaustive extraction is ensured. Analytical performance of the dynamic extractor is evaluated for fractionation analysis of a real coal fly ash and BCR-176R fly ash certified reference material. No significant differences were found at the 0.05 significance level between summation of leached concentrations in each fraction plus residue and concentration values of BCR-176R, thus revealing the accuracy of the automated method. Overall extractable pools of trace metals in three samples are separated in less than 115 min, even for highly contaminated ashes, versus 18-24 h per fraction in equilibrium leaching tests. The multiple stirred-flow cell assembly is thus suitable for routine risk assessment studies of industrial solid byproduct.
Labelling schemes: From a consumer perspective
DEFF Research Database (Denmark)
Juhl, Hans Jørn; Stacey, Julia
2000-01-01
Labelling of food products attracts a lot of political attention these days. As a result of a number of food scandals, most European countries have acknowledged the need for more information and better protection of consumers. Labelling schemes are one way of informing and guiding consumers....... However, initiatives in relation to labelling schemes seldom take their point of departure in consumers' needs and expectations; and in many cases, the schemes are defined by the institutions guaranteeing the label. It is therefore interesting to study how consumers actually value labelling schemes....... A recent MAPP study has investigated the value consumers attach the Government-controlled labels 'Ø-mærket' and 'Den Blå Lup' and the private supermarket label 'Mesterhakket' when they purchase minced meat. The results reveal four consumer segments that use labelling schemes for food products very...
COMMERCIAL SNF ACCIDENT RELEASE FRACTIONS
Energy Technology Data Exchange (ETDEWEB)
S.O. Bader
1999-10-18
The purpose of this design analysis is to specify and document the total and respirable fractions for radioactive materials that are released from an accident event at the Monitored Geologic Repository (MGR) involving commercial spent nuclear fuel (CSNF) in a dry environment. The total and respirable release fractions will be used to support the preclosure licensing basis for the MGR. The total release fraction is defined as the fraction of total CSNF assembly inventory, typically expressed as an activity inventory (e.g., curies), of a given radionuclide that is released to the environment from a waste form. The radionuclides are released from the inside of breached fuel rods (or pins) and from the detachment of radioactive material (crud) from the outside surfaces of fuel rods and other components of fuel assemblies. The total release fraction accounts for several mechanisms that tend to retain, retard, or diminish the amount of radionuclides that are available for transport to dose receptors or otherwise can be shown to reduce exposure of receptors to radiological releases. The total release fraction includes a fraction of airborne material that is respirable and could result in inhalation doses. This subset of the total release fraction is referred to as the respirable release fraction. Potential accidents may involve waste forms that are characterized as either bare (unconfined) fuel assemblies or confined fuel assemblies. The confined CSNF assemblies at the MGR are contained in shipping casks, canisters, or disposal containers (waste packages). In contrast to the bare fuel assemblies, the container that confines the fuel assemblies has the potential of providing an additional barrier for diminishing the total release fraction should the fuel rod cladding breach during an accident. However, this analysis will not take credit for this additional bamer and will establish only the total release fractions for bare unconfined CSNF assemblies, which may however be
International Nuclear Information System (INIS)
Bhunia, C.T.
2007-07-01
Packet combining scheme is a well defined simple error correction scheme for the detection and correction of errors at the receiver. Although it permits a higher throughput when compared to other basic ARQ protocols, packet combining (PC) scheme fails to correct errors when errors occur in the same bit locations of copies. In a previous work, a scheme known as Packet Reversed Packet Combining (PRPC) Scheme that will correct errors which occur at the same bit location of erroneous copies, was studied however PRPC does not handle a situation where a packet has more than 1 error bit. The Modified Packet Combining (MPC) Scheme that can correct double or higher bit errors was studied elsewhere. Both PRPC and MPC schemes are believed to offer higher throughput in previous studies, however neither adequate investigation nor exact analysis was done to substantiate this claim of higher throughput. In this work, an exact analysis of both PRPC and MPC is carried out and the results reported. A combined protocol (PRPC and MPC) is proposed and the analysis shows that it is capable of offering even higher throughput and better error correction capability at high bit error rate (BER) and larger packet size. (author)
Mapping the Potentially Affected Fraction (PAF) of species as an indicator of generic toxic stress
Klepper O; Meent D van de; ECO
1997-01-01
The Potentially Affected Fraction (PAF) is the fraction of species exposed above the no-effect concentration (NOEC). The PAF is a measure that allows a comparison in toxic stress between substances and areas. In the report the PAF is calculated for four heavy metals (cadmium, copper, lead and zinc)
Sparse Reconstruction Schemes for Nonlinear Electromagnetic Imaging
Desmal, Abdulla
2016-03-01
Electromagnetic imaging is the problem of determining material properties from scattered fields measured away from the domain under investigation. Solving this inverse problem is a challenging task because (i) it is ill-posed due to the presence of (smoothing) integral operators used in the representation of scattered fields in terms of material properties, and scattered fields are obtained at a finite set of points through noisy measurements; and (ii) it is nonlinear simply due the fact that scattered fields are nonlinear functions of the material properties. The work described in this thesis tackles the ill-posedness of the electromagnetic imaging problem using sparsity-based regularization techniques, which assume that the scatterer(s) occupy only a small fraction of the investigation domain. More specifically, four novel imaging methods are formulated and implemented. (i) Sparsity-regularized Born iterative method iteratively linearizes the nonlinear inverse scattering problem and each linear problem is regularized using an improved iterative shrinkage algorithm enforcing the sparsity constraint. (ii) Sparsity-regularized nonlinear inexact Newton method calls for the solution of a linear system involving the Frechet derivative matrix of the forward scattering operator at every iteration step. For faster convergence, the solution of this matrix system is regularized under the sparsity constraint and preconditioned by leveling the matrix singular values. (iii) Sparsity-regularized nonlinear Tikhonov method directly solves the nonlinear minimization problem using Landweber iterations, where a thresholding function is applied at every iteration step to enforce the sparsity constraint. (iv) This last scheme is accelerated using a projected steepest descent method when it is applied to three-dimensional investigation domains. Projection replaces the thresholding operation and enforces the sparsity constraint. Numerical experiments, which are carried out using
Can a sponge fractionate isotopes?
Patel, B; Patel, S; Balani, M C
1985-03-22
The study has unequivocally demonstrated that siliceous sponges Spirastrella cuspidifera and Prostylyssa foetida from the same microecological niche exhibit a high degree of species specificity, while accumulating a host of heavy metal ions (Ni, Cr, Cd, Sn, Ti, Mo, Zr). S. cuspidifera accumulated, in addition, 60Co and 63Ni, showing discrimination against other radionuclides, 137Cs and 131I, present in the ambient waters receiving controlled low level waste discharges from a B.W.R. nuclear power station. P. foetida, on the other hand, accumulated only 131I and showed discrimination against other radionuclides including 60Co, although the stable iodine concentrations in both the sponges were the same. The specific activity of 60Co (in becquerels per gram of 59Co) in S. cuspidifera and 131I (in becquerels per gram of 127I) in P. foetida were at least two orders of magnitude greater than in the ambient sea water. That of 63Ni (in becquerels per gram of 62Ni) in S. cuspidifera, on the other hand, was lower by two orders of magnitude than in either abiotic matrices from the same environment. Thus, not only did both the species show bioaccumulation of a specific element, but also preferential uptake of isotopes of the same element, though they were equally available for intake. Such differential uptake of isotopes can possibly be explained in terms of two quite different mechanisms operating, each applicable in a particular case. One is that the xenobiotic isotope enters the environment in a physicochemical form or as a complex different from that of its natural counterpart. If equilibration with the latter is slow, so that the organism acquires the xenobiotic in an unfamiliar chemical context, it may treat it as a chemically distinct entity so that its concentration factor differs from that of stable isotope, thus changing the specific activity. Alternatively, if the xenobiotic is present in the same chemical form as the stable isotope, the only way in which specific
Financial Planning with Fractional Goals
M.H. Goedhart; J. Spronk (Jaap)
1995-01-01
textabstractWhen solving financial planning problems with multiple goals by means of multiple objective programming, the presence of fractional goals leads to technical difficulties. In this paper we present a straightforward interactive approach for solving such linear fractional programs with
Deterministic ratchets for suspension fractionation
Kulrattanarak, T.
2010-01-01
Driven by the current insights in sustainability and technological development in biorefining natural renewable resources, the food industry has taken an interest in fractionation of agrofood materials, like milk and cereal crops. The purpose of fractionation is to split the raw material in
Rational Exponentials and Continued Fractions
Denny, J. K.
2012-01-01
Using continued fraction expansions, we can approximate constants, such as pi and e, using an appropriate integer n raised to the power x[superscript 1/x], x a suitable rational. We review continued fractions and give an algorithm for producing these approximations.
The fractional-order modeling and synchronization of electrically coupled neuron systems
Moaddy, K.
2012-11-01
In this paper, we generalize the integer-order cable model of the neuron system into the fractional-order domain, where the long memory dependence of the fractional derivative can be a better fit for the neuron response. Furthermore, the chaotic synchronization with a gap junction of two or multi-coupled-neurons of fractional-order are discussed. The circuit model, fractional-order state equations and the numerical technique are introduced in this paper for individual and multiple coupled neuron systems with different fractional-orders. Various examples are introduced with different fractional orders using the non-standard finite difference scheme together with the Grünwald-Letnikov discretization process which is easily implemented and reliably accurate. © 2011 Elsevier Ltd. All rights reserved.
Fractional random walk lattice dynamics
Michelitsch, T. M.; Collet, B. A.; Riascos, A. P.; Nowakowski, A. F.; Nicolleau, F. C. G. A.
2017-02-01
We analyze time-discrete and time-continuous ‘fractional’ random walks on undirected regular networks with special focus on cubic periodic lattices in n = 1, 2, 3,.. dimensions. The fractional random walk dynamics is governed by a master equation involving fractional powers of Laplacian matrices {{L}\\fracα{2}}} where α =2 recovers the normal walk. First we demonstrate that the interval 0expressions for the transition matrix of the fractional random walk and closely related the average return probabilities. We further obtain the fundamental matrix {{Z}(α )} , and the mean relaxation time (Kemeny constant) for the fractional random walk. The representation for the fundamental matrix {{Z}(α )} relates fractional random walks with normal random walks. We show that the matrix elements of the transition matrix of the fractional random walk exihibit for large cubic n-dimensional lattices a power law decay of an n-dimensional infinite space Riesz fractional derivative type indicating emergence of Lévy flights. As a further footprint of Lévy flights in the n-dimensional space, the transition matrix and return probabilities of the fractional random walk are dominated for large times t by slowly relaxing long-wave modes leading to a characteristic {{t}-\\frac{n{α}} -decay. It can be concluded that, due to long range moves of fractional random walk, a small world property is emerging increasing the efficiency to explore the lattice when instead of a normal random walk a fractional random walk is chosen.
Permutation entropy of fractional Brownian motion and fractional Gaussian noise
International Nuclear Information System (INIS)
Zunino, L.; Perez, D.G.; Martin, M.T.; Garavaglia, M.; Plastino, A.; Rosso, O.A.
2008-01-01
We have worked out theoretical curves for the permutation entropy of the fractional Brownian motion and fractional Gaussian noise by using the Bandt and Shiha [C. Bandt, F. Shiha, J. Time Ser. Anal. 28 (2007) 646] theoretical predictions for their corresponding relative frequencies. Comparisons with numerical simulations show an excellent agreement. Furthermore, the entropy-gap in the transition between these processes, observed previously via numerical results, has been here theoretically validated. Also, we have analyzed the behaviour of the permutation entropy of the fractional Gaussian noise for different time delays
Ponzi scheme diffusion in complex networks
Zhu, Anding; Fu, Peihua; Zhang, Qinghe; Chen, Zhenyue
2017-08-01
Ponzi schemes taking the form of Internet-based financial schemes have been negatively affecting China's economy for the last two years. Because there is currently a lack of modeling research on Ponzi scheme diffusion within social networks yet, we develop a potential-investor-divestor (PID) model to investigate the diffusion dynamics of Ponzi scheme in both homogeneous and inhomogeneous networks. Our simulation study of artificial and real Facebook social networks shows that the structure of investor networks does indeed affect the characteristics of dynamics. Both the average degree of distribution and the power-law degree of distribution will reduce the spreading critical threshold and will speed up the rate of diffusion. A high speed of diffusion is the key to alleviating the interest burden and improving the financial outcomes for the Ponzi scheme operator. The zero-crossing point of fund flux function we introduce proves to be a feasible index for reflecting the fast-worsening situation of fiscal instability and predicting the forthcoming collapse. The faster the scheme diffuses, the higher a peak it will reach and the sooner it will collapse. We should keep a vigilant eye on the harm of Ponzi scheme diffusion through modern social networks.
Optimal Face-Iris Multimodal Fusion Scheme
Directory of Open Access Journals (Sweden)
Omid Sharifi
2016-06-01
Full Text Available Multimodal biometric systems are considered a way to minimize the limitations raised by single traits. This paper proposes new schemes based on score level, feature level and decision level fusion to efficiently fuse face and iris modalities. Log-Gabor transformation is applied as the feature extraction method on face and iris modalities. At each level of fusion, different schemes are proposed to improve the recognition performance and, finally, a combination of schemes at different fusion levels constructs an optimized and robust scheme. In this study, CASIA Iris Distance database is used to examine the robustness of all unimodal and multimodal schemes. In addition, Backtracking Search Algorithm (BSA, a novel population-based iterative evolutionary algorithm, is applied to improve the recognition accuracy of schemes by reducing the number of features and selecting the optimized weights for feature level and score level fusion, respectively. Experimental results on verification rates demonstrate a significant improvement of proposed fusion schemes over unimodal and multimodal fusion methods.
Adaptive Packet Combining Scheme in Three State Channel Model
Saring, Yang; Bulo, Yaka; Bhunia, Chandan Tilak
2018-01-01
The two popular techniques of packet combining based error correction schemes are: Packet Combining (PC) scheme and Aggressive Packet Combining (APC) scheme. PC scheme and APC scheme have their own merits and demerits; PC scheme has better throughput than APC scheme, but suffers from higher packet error rate than APC scheme. The wireless channel state changes all the time. Because of this random and time varying nature of wireless channel, individual application of SR ARQ scheme, PC scheme and APC scheme can't give desired levels of throughput. Better throughput can be achieved if appropriate transmission scheme is used based on the condition of channel. Based on this approach, adaptive packet combining scheme has been proposed to achieve better throughput. The proposed scheme adapts to the channel condition to carry out transmission using PC scheme, APC scheme and SR ARQ scheme to achieve better throughput. Experimentally, it was observed that the error correction capability and throughput of the proposed scheme was significantly better than that of SR ARQ scheme, PC scheme and APC scheme.
Deitmar schemes, graphs and zeta functions
Mérida-Angulo, Manuel; Thas, Koen
2017-07-01
In Thas (2014) it was explained how one can naturally associate a Deitmar scheme (which is a scheme defined over the field with one element, F1) to a so-called "loose graph" (which is a generalization of a graph). Several properties of the Deitmar scheme can be proven easily from the combinatorics of the (loose) graph, and known realizations of objects over F1 such as combinatorial F1-projective and F1-affine spaces exactly depict the loose graph which corresponds to the associated Deitmar scheme. In this paper, we first modify the construction of loc. cit., and show that Deitmar schemes which are defined by finite trees (with possible end points) are "defined over F1" in Kurokawa's sense; we then derive a precise formula for the Kurokawa zeta function for such schemes (and so also for the counting polynomial of all associated Fq-schemes). As a corollary, we find a zeta function for all such trees which contains information such as the number of inner points and the spectrum of degrees, and which is thus very different than Ihara's zeta function (which is trivial in this case). Using a process called "surgery," we show that one can determine the zeta function of a general loose graph and its associated {Deitmar, Grothendieck}-schemes in a number of steps, eventually reducing the calculation essentially to trees. We study a number of classes of examples of loose graphs, and introduce the Grothendieck ring ofF1-schemes along the way in order to perform the calculations. Finally, we include a computer program for performing more tedious calculations, and compare the new zeta function to Ihara's zeta function for graphs in a number of examples.
International Nuclear Information System (INIS)
Bergqvist, U.
1983-12-01
The aim of this report is to estimate the exposure to various metals and metal compounds and discuss the available information of the possible toxic effects of these metals and compounds. In the first section, some metals are defined as those with either a large or a fast increasing exposure to living organisms. The available information on toxicity is discussed in the second section. In the third section interesting metals are defined as compounds having a large exposure and an apparent insufficient knowledge of their possible toxic effects. Comments on each of these metals are also to be found in the third section. (G.B.)
Cognitive radio networks dynamic resource allocation schemes
Wang, Shaowei
2014-01-01
This SpringerBrief presents a survey of dynamic resource allocation schemes in Cognitive Radio (CR) Systems, focusing on the spectral-efficiency and energy-efficiency in wireless networks. It also introduces a variety of dynamic resource allocation schemes for CR networks and provides a concise introduction of the landscape of CR technology. The author covers in detail the dynamic resource allocation problem for the motivations and challenges in CR systems. The Spectral- and Energy-Efficient resource allocation schemes are comprehensively investigated, including new insights into the trade-off
Finite-volume scheme for anisotropic diffusion
Energy Technology Data Exchange (ETDEWEB)
Es, Bram van, E-mail: bramiozo@gmail.com [Centrum Wiskunde & Informatica, P.O. Box 94079, 1090GB Amsterdam (Netherlands); FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands); Koren, Barry [Eindhoven University of Technology (Netherlands); Blank, Hugo J. de [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, The Netherlands" 1 (Netherlands)
2016-02-01
In this paper, we apply a special finite-volume scheme, limited to smooth temperature distributions and Cartesian grids, to test the importance of connectivity of the finite volumes. The area of application is nuclear fusion plasma with field line aligned temperature gradients and extreme anisotropy. We apply the scheme to the anisotropic heat-conduction equation, and compare its results with those of existing finite-volume schemes for anisotropic diffusion. Also, we introduce a general model adaptation of the steady diffusion equation for extremely anisotropic diffusion problems with closed field lines.
Vector domain decomposition schemes for parabolic equations
Vabishchevich, P. N.
2017-09-01
A new class of domain decomposition schemes for finding approximate solutions of timedependent problems for partial differential equations is proposed and studied. A boundary value problem for a second-order parabolic equation is used as a model problem. The general approach to the construction of domain decomposition schemes is based on partition of unity. Specifically, a vector problem is set up for solving problems in individual subdomains. Stability conditions for vector regionally additive schemes of first- and second-order accuracy are obtained.
Autonomous Droop Scheme With Reduced Generation Cost
DEFF Research Database (Denmark)
Nutkani, Inam Ullah; Loh, Poh Chiang; Wang, Peng
2014-01-01
) of the microgrid. To reduce this TGC without relying on fast communication links, an autonomous droop scheme is proposed here, whose resulting power sharing is decided by the individual DG generation costs. Comparing it with the traditional scheme, the proposed scheme retains its simplicity and it is hence more....... This objective might, however, not suit microgrids well since DGs are usually of different types, unlike synchronous generators. Other factors like cost, efficiency, and emission penalty of each DG at different loading must be considered since they contribute directly to the total generation cost (TGC...
MADR: metal artifact detection and reduction
Jaiswal, Sunil Prasad; Ha, Sungsoo; Mueller, Klaus
2016-04-01
Metal in CT-imaged objects drastically reduces the quality of these images due to the severe artifacts it can cause. Most metal artifacts reduction (MAR) algorithms consider the metal-affected sinogram portions as the corrupted data and replace them via sophisticated interpolation methods. While these schemes are successful in removing the metal artifacts, they fail to recover some of the edge information. To address these problems, the frequency shift metal artifact reduction algorithm (FSMAR) was recently proposed. It exploits the information hidden in the uncorrected image and combines the high frequency (edge) components of the uncorrected image with the low frequency components of the corrected image. Although this can effectively transfer the edge information of the uncorrected image, it also introduces some unwanted artifacts. The essential problem of these algorithms is that they lack the capability of detecting the artifacts and as a result cannot discriminate between desired and undesired edges. We propose a scheme that does better in these respects. Our Metal Artifact Detection and Reduction (MADR) scheme constructs a weight map which stores whether a pixel in the uncorrected image belongs to an artifact region or a non-artifact region. This weight matrix is optimal in the Linear Minimum Mean Square Sense (LMMSE). Our results demonstrate that MADR outperforms the existing algorithms and ensures that the anatomical structures close to metal implants are better preserved.