British Library Electronic Table of Contents (United Kingdom)

Purpose - Based upon the E-VALUE model developed, this paper aims to investigate the impact of e-commerce usage on business performance in the tourism sector. Design/methodology/approach - A cross-sectional survey is carried out on 165 Malaysian firms involved in the tourism sector (hotels, resorts, and hospitals engaged in health tourism) through the use of a structured questionnaire. Findings - The structural equation modeling results indicate that technology competency, firm size, firm scope, web-technology investment, pressure intensity, and back-end usage have significant influence on e-commerce usage. Among these variables, back-end integration is found to function as a mediator. E-commerce experience (in years) is found to moderate the relationship between e-commerce usage and busin...

UK PubMed Central (United Kingdom)

Study objectiveThe study aim was to improve our understanding of the relationships between contextual socioeconomic characteristics and coronary heart disease (CHD)...Full Text Available

International Nuclear Information System (INIS)

Attention is given to the folowing topics: population I and II variable stars; LP variables, the sun, and mass determination; and predegenerate and degenerate variables. Particular papers are presented on alternative evolutionary approaches to the absolute magnitude of the RR Lyrae variables; the evolution of the Cepheid stars; nonradial pulsations in rapidly rotating Delta Scuti stars; dynamical models of dust shells around Mira variables; and pulsations of central stars of planetary nebulae.

Energy Technology Data Exchange (ETDEWEB)

In recent years the modelling of interannual climate variability has been studied, the atmospheric energy and water cycles, and climate simulations with the ECHAM3 model. In addition, the climate simulations of several models have been compared with special emphasis in the area of northern Europe

UK PubMed Central (United Kingdom)

The secreted Bv8 protein has been recently characterized as a regulator of myeloid cell mobilization and a neutrophil-derived mediator of tumor angiogenesis in several xenografts, but its role in tumor...Full Text Available

UK PubMed Central (United Kingdom)

Neuronal death is known to trigger reactive microgliosis. However, little is known regarding the manner by which microglia are activated by injured neurons and how microgliosis participates...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundNeuropathic pain (NP) is partially mediated by neuroinflammatory mechanisms, and also modulates local neurogenic inflammation. Dietary lipids, in particular the total amount...Full Text Available

UK PubMed Central (United Kingdom)

Average human behavior in cue combination tasks is well predicted by Bayesian inference models. As this capability is acquired over developmental timescales, the question arises, how it is learned....Full Text Available

British Library Electronic Table of Contents (United Kingdom)

Sleep symptoms are a prominent feature of mental health disorders like PTSD and depression. However, it is unknown whether sleep symptoms mediate the relationship between combat stress and these disorders. We examined the mediating role of sleep symptoms on the relationship between combat stress and PTSD; and the relationship between combat stress and depression using data from 576 Army veterans of the Iraq War surveyed in 2004. Correlational analyses revealed that when insomnia was included in the model, the correlation between combat stressors and other depression symptoms decreased by 65%; and when nightmares were included in the model, the correlation between combat stressors and other PTSD symptoms decreased by 69%. We replicated these analyses using individual items assessing PTSD an...

International Nuclear Information System (INIS)

Recent developments in the analysis of Mira atmosphere, the determination of the pulsation mode, the problem of mass loss, and the evolution of the Mira variables are covered. Model atmospheres for Mira variables, including the opacities of the molecules expected in very late M-type atmospheres are discussed. The pulsation constant for Omicron Ceti is evaluated using T(eff) = 2900 + or - 200 K, and it is concluded that Miras are fundamental mode pulsators. The importance of molecular opacity to the driving of mass loss is evaluated, and it is pointed out that the radiation pressure on molecules is not a major factor in driving mass loss from Mira. Mass loss is considered as a factor in the calculations of the periods for Mira variables. 30 refs.

Science.gov (United States)

A methodology and hypothetical case study are presented for incorporation of uncertainty and variability into calculations of human health risk appropriate for regional, or basin-scale, groundwater management problems. Uncertainty in well water concentration is introduced through complex contaminant migration patterns in the subsurface. Variability is considered in parameters related to individual behavior patterns and biological effects and to groundwater extraction and distribution networks. A joint uncertainty and variability (JUV) analysis is used to generate a two-dimensional distribution or risk surface that spans both transport uncertainty as well as individual variability. Cuts in this distributional surface (fractiles of variability and percentiles of uncertainty) are presented and discussed. Comparisons with alternative approaches based upon deterministic transport ...

Energy Technology Data Exchange (ETDEWEB)

The role of natural enemies in the regulation of populations is one of the major questions facing population ecologists. Simplification have led to two theoretical ways of incorporating the role of natural enemies in single ecological models: diffusion models and patch-type models. The predictions of the models are different because of the way variability is incorporated. Three equations are presented for diffusion models and one for patch models. Since the two types of models apply at different combinations of spatial and temporal scales, the right model(s) to choose for a particular study requires careful assessment. A continuing dialogue between experimentalists and theoreticians will lead to a better understanding of natural systems such as those that occur in biological control.

British Library Electronic Table of Contents (United Kingdom)

In this study, we investigated the kinetics of linoleic acid production via lipase-mediated hydrolysis of corn DDGS oil in a batch reactor with continuous mechanical agitation and developed a kinetic model that incorporated the product inhibition to study the complete hydrolysis. The model agreed very well with observed data; though situations with low enzyme dosage or low stirring rates were modeled successfully without product inhibition, actual product concentration in such situations was too low to exert any inhibitory effects. Increasing the enzyme concentration increased hydrolysis, and beyond certain enzyme concentrations, effects tended to fade away because of excessive enzyme desorption from the interface. An enzyme dosage within the range of 40-60KLU/L of oil dispersion could be ...

CERN Document Server

In undirected graphical models, learning the graph structure and learning the functions that relate the predictive variables (features) to the responses given the structure are two topics that have been widely investigated in machine learning and statistics. Learning graphical models in two stages will have problems because graph structure may change after considering the features. The main contribution of this paper is the proposed method that learns the graph structure and functions on the graph at the same time. General graphical models with binary outcomes conditioned on predictive variables are proved to be equivalent to multivariate Bernoulli model. The reparameterization of the potential functions in graphical model by conditional log odds ratios in multivariate Bernoulli model offers advantage in the ...

British Library Electronic Table of Contents (United Kingdom)

This study validates a research model that examines usage of instant messaging (IM) from the aspect of online social support. Drawing on the social capital theory, this study postulates that IM usage is indirectly affected by social support via the mediation of the following six dimensions of social capital: commitment, reciprocity, shared codes and language, shared narratives, centrality, and network ties. The model tests data obtained from business organizations in Taiwan, and the results suggest that the indirect influence of social support on IM usage through shared codes and language is significant, and the indirect influence of social support on IM usage through centrality is also significant. Managerial implications and limitations of the empirical findings are provided.

Energy Technology Data Exchange (ETDEWEB)

This study examines the sensitivity of the travel time distribution predicted by a reference case model to (1) scale of representation of the model parameters, (2) size of the model domain, (3) correlation range of log-transmissivity, and (4) cross correlations between transmissivity and effective thickness. The basis for the reference model is the preliminary stochastic travel time model previously documented by the Basalt Waste Isolation Project. Results of this study show the following. The variability of the predicted travel times can be adequately represented when the ratio between the size of the zones used to represent the model parameters and the log-transmissivity correlation range is less than about one-fifth. The size of the model domain and the types of boundary conditions can have a strong impact on the ...

International Nuclear Information System (INIS)

The fatigue life variability of the #alpha#+#beta# titanium alloy, Ti-6Al-2Sn-4Zr-6Mo increased with decreasing stress level. The variability in life was found to be due to segregation of lives due to two failure mechanisms. A bimodal cumulative distribution model was shown to accurately describe the combined failure modes. The nominal failure processes for the two regimes were similar, with crack nucleation occurring in equiaxed #alpha#p particles, irrespective of life or stress level. However the variability in life was not controlled by the size of the crack-nucleating #alpha#p, but rather by the ability of the material to distribute deformation and avoid early crack nucleation.

British Library Electronic Table of Contents (United Kingdom)

The study has analysed the effects of various factors on hydroelectric power generation potential to include climate change/variability, water demand, and installation of proposed hydroelectric power schemes in the Zambezi River Basin. An assessment of historical (1970?2000) power potential in relation to climate change/variability at existing hydro electric power schemes(Cahora Bassa, Kariba, Kafue Gorge and Itezhi-Tezhi) in the Zambezi River Basin was conducted. The correlation of hydroelectric power potential with climate change/variability aimed at observing the link and extent of influence of the latter on the former was investigated. In order to predict the future outlook of hydro electric power potential, General Circulation Models (GCM) were used to generate projected precipitation...

Energy Technology Data Exchange (ETDEWEB)

A mathematical model is proposed for three-phase filtering which is a particular case of a more general model of filtering multiple component mixtures and makes it possible to describe three-phase filtering flows under conditions where the pressure of saturation is variable in time and in space. In the proposed model, the system of unknown functions is selected so that it makes it possible to trace fairly simply the pressure of saturation and to compute the corresponding equation coefficients.

Science.gov (United States)

Reciprocity is one of the defining features of social exchange and social life, yet exchange theorists have tended to take it for granted. Drawing on work from a decade-long theoretical research program, I argue that reciprocity is structured and variable across different forms of exchange, that these variations in the structure of reciprocity have profound effects on the emergence of integrative bonds of trust and solidarity, and that these effects are explained and mediated by a set of risk- and conflict-based processes. I discuss the consequences of this work for organizational theories of embeddedness and the production of social capital through network ties. Finally, I ask how the structure of networks and the structure of reciprocity are related to one another, and explore possible implications of the structure of reciprocity for exchange theorists' assumptions about actor motivations. (Contains 3 figures and 5 footnotes.)

British Library Electronic Table of Contents (United Kingdom)

Summary Background Current management of egg allergy relies on egg elimination from the diet. It does not protect patients from reactions after accidental ingestion of the food and it has a negative influence on quality of life. To solve these problems, some desensitization protocols have been described that are safe and effective, but only one study of a rush regimen for egg with a small patient sample has been published. Objective To evaluate the safety, efficacy and immunologic effects of an oral rush desensitization protocol for immediate egg allergy. Methods Subjects aged 5 years or older with symptomatic IgE-mediated allergy to hen's egg underwent a 5-day oral tolerance induction regimen and were subsequently maintained on a regular egg intake. The variables studied were the reaction...

UK PubMed Central (United Kingdom)

Simulations with a regional chemical transport model show that anthropogenic emissions of volatile organic compounds and nitrogen oxides (NO_x = NO + NO₂) lead to a dramatic diurnal...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundStudies conducted in developed countries using economic models show that individual- and household- level variables are important determinants of health insurance ownership....Full Text Available

UK PubMed Central (United Kingdom)

Although caloric restriction (CR) has been shown to increase lifespan in various animal models, the mechanisms underlying this phenomenon have not yet been revealed. We developed an in vitro...Full Text Available

UK PubMed Central (United Kingdom)

Despite intensive efforts, the intracellular signaling pathways that mediate apoptosis remain unclear. The human B lymphoma cell line, B104, possesses characteristics that make it an attractive model...Full Text Available

UK PubMed Central (United Kingdom)

Stress exposure increases the risk of addictive drug use in human and animal models of drug addiction by mechanisms that are not completely understood. Mice subjected to repeated forced swim stress...Full Text Available

CERN Document Server

We construct representation of the Separated Variables (SoV) for the quantum SL(2,R) Heisenberg closed spin chain and obtain the integral representation for the eigenfunctions of the model. We calculate explicitly the Sklyanin measure defining the scalar product in the SoV representation and demonstrate that the language of Feynman diagrams is extremely useful in establishing various properties of the model. The kernel of the unitary transformation to the SoV representation is described by the same "pyramid diagram" as appeared before in the SoV representation for the SL(2,C) spin magnet. We argue that this kernel is given by the product of the Baxter Q-operators projected onto a special reference state.

British Library Electronic Table of Contents (United Kingdom)

Abstract In this paper, a new predictive model that can forecast the performance of a vertical axis wind turbine (VAWT) is presented. The new model includes four primary variables (rotor velocity, wind velocity, air density, and turbine power output) as well as five geometrical variables (rotor radius, turbine height, turbine width, stator spacing, and stator angle). These variables are reduced to include the power coefficient (Cp) and tip speed ratio (TSR). A power coefficient correlation for a novel VAWT (called a Zephyr Vertical axis Wind Turbine (ZVWT)) is developed. The turbine is an adaptation of the Savonius design. The new correlation can predict the turbine's performance for altered stator geometry and varying operating conditions. Numerical simulations with a rotating reference f...

British Library Electronic Table of Contents (United Kingdom)

Purpose Nonpoint sources (NPS) pollution has been an important cause for water quality impairment worldwide. To take the temporal variations of both NPS pollution and in-stream attenuation into consideration, an inverse modeling approach and the load duration curve (LDC) method were combined for variable nutrient total maximum daily load (TMDL) development. Methods Water quality and hydrological parameters were monitored monthly along the ChangLe River system in 2004?2008. The catchment NPS export load (EL) and TMDL for total nitrogen (TN) were estimated by the inverse format of an existing stream nutrient transport equation. The LDC method was used to describe the variability of EL, TMDL, requiring load (RLR) and percent (the ratio between the RLR and the EL, RPR) reduction, and then to s...

International Nuclear Information System (INIS)

Energy confinement in W7-AS has been analyzed in terms of dimensionally exact form free functions employing Bayesian probability theory. The confinement function was set up as a linear combination of dimensionally exact power law terms as already proposed very early by Connor and Taylor. Generation of this expansion basis is dictated by the basic plasma model which one assumes. Based upon data accumulated in W7-AS, which contains the energy content for a wide variety of variable settings, predictions for single variable scans are made. The scaling functions for density and power scans, respectively, are in quantitative agreement with data collected in W7-AS. The result of a single variable scan is therefore already hidden in the data obtained for arbitrary variable choices and can be extracted from the latter by a proper data analysis. Furthermore, the optimal ...

British Library Electronic Table of Contents (United Kingdom)

A modified variable structure interacting multiple model (M-VSIMM) estimator for complex hybrid maneuver target tracking is presented. The M-VSIMM could potentially be applied to fire control systems (FCS) used on warships. Target model groups were designed using 3D dimensional dynamic target models. Optimal model group selection logic was proposed, contrary to the activation and termination logic in the original VSIMM. The system will respond faster with optimal model group selection logic. After performing simulations, the tracking performances of the Kalman, ?-?(-?), VDIE, IMM and M-VSIMM filters were compared under various maneuvering conditions.

British Library Electronic Table of Contents (United Kingdom)

The primary objective of batch data as trajectory alignment (or synchronization) is to standardize the data sampling per batch according to the evolution of the process, and secondarily to homogenize the samples per run. The use of an indicator variable performs both objectives well. Two examples from the pharmaceutical sector are discussed to illustrate the different ways to deal with uneven samples across batches and across variables in the same batch. Since trajectory alignment requires large time investment, a simple triage approach is proposed to assess the need to analyze the dynamics of a given process and hence perform alignment. The presented examples are representative of a broad variety of batch processes that are operated by recipe in the pharmaceutical sector. In our experienc...

Science.gov (United States)

Divergence between aircraft engine emission regulations proposed by EPA and ICAO is discussed. Every engine, upon entering service, requires a certificate as to its compliance with emission standards. It is shown that despite the large variability in the measurements, it is possible to devise a certification procedure requiring the testing of one engine only. Statistical modeling of such a test at the 5% significance level is described. Values of the parameter standard deviation/mean recommended as certification standards for various pollutants are given. Features of a rational certification scheme to be formulated are outlined.

Energy Technology Data Exchange (ETDEWEB)

The present volume on modeling of batteries and fuel cells discusses the significance of the effectiveness factor for flooded porous electrodes, active pore distribution spectroscopy for characterizing porous battery electrodes, the agglomerate model for porous electrodes, and dynamic-performance measurements of battery cells for electric vehicles and other applications. Attention is given to mathematical modeling of a primary zinc/air battery, mathematical modeling of Grace Li-TiS2 cells, modeling of electrocrystallization processes in battery systems, and rotating disk electrode studies in molten Li/K carbonate eutectic. Topics addressed include the variability of nickel oxide cathode dissolution in molten carbonate fuel cells, water transport properties of fuel cell ionomers, modeling water content effects in polymer electrolyte fuel ...

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The Environmental Kuznets Curve (EKC) hypothesis states that pollution levels increase as a country develops, but begin to decrease as rising incomes pass beyond a turning point. In EKC analyses, the relationship between environmental degradation and income is usually expressed as a quadratic function with the turning point occurring at a maximum pollution level. Other explanatory variables have been included in these models, but income regularly has had the most significant effect on indicators of environmental quality. One variable consistently omitted in these relationships is the price of energy. This paper analyzes previous models to illustrate the importance of prices in these models and then includes prices in an econometric EKC framework testing energy/income and CO{sub 2}/income relationships. These long-run price/income models find that income is no ...

CERN Document Server

This research will be helpful for people to display the 2-dimensiona projective models of 4-variable actual problems in many fields, in order to investigate deeply those actual problems. By using the theory of N-dimensional finite rotation group of the regular polytopes, the author established the 2-dimensional projective model of 4-dimensional rectangular coordinate system, and deduced a transformation matrix, and adopt it to display successfully the 2-dimensional overall shapes of two most complicated regular polytopes 120-Cell and 600-Cell. In the meantime, the author calculated all the vertex coordinates and determine the joint relationships between adjacent vertices of the regular polytopes 120-Cell and 600-Cell. Also, this provided a pattern for displaying the 2-dimensional projective model of 4-variable actual problem.

British Library Electronic Table of Contents (United Kingdom)

Biodynamic parameters of the ragworm Nereis diversicolor from southern Spain and south England were experimentally derived to assess the inter-population variability of physiological parameters of the bioaccumulation of Ag, Cd and Zn from water and sediment. Although there were some limited variations, these were not consistent with the local metal bioavailability nor with temperature changes. Incorporating the biodynamic parameters into a defined biodynamic model, confirmed that sediment is the predominant source of Cd and Zn accumulated by the worms, accounting in each case for 99% of the overall accumulated metals, whereas the contribution of dissolved Ag to the total accumulated by the worm increased from about 27 to about 53% with increasing dissolved Ag concentration. Standardised va...

CERN Document Server

This paper introduces a new parsimonious structure for mixture of autoregressive models. the weighting coefficients are determined through latent random variables, following a hidden Markov model. We propose a dynamic programming algorithm for the application of forecasting. We also derive the limiting behavior of unconditional first moment of the process and an appropriate upper bound for the limiting value of the variance. This can be considered as long run behavior of the process. Finally we show convergence and stability of the second moment. Further, we illustrate the efficacy of the proposed model by simulation and forecasting.

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This demonstration project uses modern simulation techniques to illustrate the important technologies and design variables that an auto-designer would consider in production a high efficiency, low emissions vehicle. Simulation and modeling techniques use the idea of capturing the relationships between real components of the systems with mathematical equations. These equations are then solved on a computer to simulate the behavior or performance of the system under various conditions. In the current demonstration project, we focus on many variations of a hydrogen-powered vehicle.

CERN Document Server

We propose a new scenario that solves the slepton negative mass squared problem of the minimal supersymmetric standard model with anomaly mediated supersymmetry breaking. The solution is achieved by including three trilinear R-parity violating operators in the superpotential. The soft supersymmetry breaking terms satisfy renormalisation group invariant relations in terms of supersymmetric couplings and the overall supersymmetry breaking mass scale. Flavour changing neutral currents are naturally highly suppressed. The model predicts tan beta=4.2 +/- 1.0. Excluding sleptons, the supersymmetric particle spectrum depends upon two remaining free parameters. In the case of the R-parity violating couplings at their quasi-fixed points at a supersymmetric GUT scale, the whole sparticle spectrum approximately depends upon only one free parameter. Imposing experimental limits leads to a constrained and distinctive phenomenology. The ...

Energy Technology Data Exchange (ETDEWEB)

To assess the variability and systematic differences in polyp measurements on optical colonoscopy and CT colonography. Gastroenterologists measured 51 polyps by visual estimation, forceps comparison and linear probe. CT colonography observers randomly assessed polyp size two-dimensionally (abdominal and intermediate window) and three-dimensionally (manually and semi-automatically). Linear mixed models were used to assess the variability and systematic differences between CT colonography and optical colonoscopy techniques. The variability of forceps and linear probe measurements was comparable and both showed less variability than measurement by visual assessment. Measurements by linear probe were 0.7 mm smaller than measurements by visual assessment or by forceps. The variability of all CT colonography techniques was lower than for measurements by forceps or ...

CERN Document Server

In the paper we investigate a mathematical model describing the growth of tumor in the presence of immune response of a host organism. The dynamics of tumour and immune cells is based on the generic Michaelis-Menten kinetics describing interaction and competition between the tumour and the immune system. The appropriate phenomenological equation modeling cell-mediated immune surveillance against cancer is of the predator-prey form and within a given choice of parameters exhibits bistability. Under the influence of spontaneous weak fluctuations, the model may be analyzed in terms of a stochastic differential equation bearing the form of an overdamped Langevin-like dynamics in the external quasi-potential represented by a double well. We analyze properties of the system within the range of parameters for which the potential wells are of the same depth and when the additional perturbation describing a ...

Science.gov (United States)

We present an optimal control approach for the solidification process of a melt in a container. The process is described by a two phase Stefan problem with the free boundary (interface between the two phases) modelled as a graph. We control the evolution of the free boundary using the temperature on the container wall. The control goal consists in tracking a prescribed evolution of the free boundary. We achieve this goal by minimizing a appropriate cost functional. The resulting minimization problem is solved numerically by a steepest descent method with step size control, where the gradient of the cost functional is expressed in terms of the adjoint variables. Several numerical examples are presented which illustrate the performance of the method. The novelty of the approach presented consists in using a sharp interface model for the control of the free boundary. This guarantees direct access to the free boundary as ...

International Nuclear Information System (INIS)

In the case wherein nonlinear seismic response analyses are carried out, the response values vary due to the variations in materials and modeling. In this paper, nonlinear analyses of several random variables are carried out using: i. a conventional method; ii. a two-point estimation method (i. and ii. are simplified methods); and iii. Monte Carlo simulation (detailed method) to examine the variability of the response in the excessive nonlinear range for seismic responses of shear walls. The analyses are performed to a PWR-3 loop type reactor building which is one of the most typical reactor buildings in Japan. The variations are considered in specified compressive strength of concrete, concrete damping factor, shear wave velocity of soil and shapes of shear stress-strain relation curves of shear walls. As the results by the two simplified methods closely matched the Monte Carlo simulation results, the appropriateness for ...

Energy Technology Data Exchange (ETDEWEB)

Multiple linear regression, principal component analysis, partial least squares, polynomial regression and artificial neural networks are popular techniques for process modeling. An industrial case study illustrates some of these technologies, with an emphasis on artificial neural networks. Experience with this and other projects indicates that while neural network models, combined with partial least squares when necessary, are an excellent tool for modeling, linear techniques may also be appropriate in some cases. Regardless of the specific method used, software analyzers are an attractive lower-cost alterative to hardware options in some monitoring applications. From a fundamental point of view, the result of chemical analysis can be considered as the dependent variable(s) of a process system having a number of independent variables. The independent variables ...

British Library Electronic Table of Contents (United Kingdom)

A dense Pd-Ag membrane reactor (MR) with 100% hydrogen selectivity packed with either Rh/La2O3 or Rh/La2O3-SiO2 as catalysts was used to carry out the dry reforming of methane. The membrane reactor simulation was performed using a well-known reactor model. For this purpose, we employed the equations derived from complete kinetic studies of the dry reforming of methane reaction in connection with both catalysts. In addition, we developed the kinetic equation for the reverse water gas shift reaction (RWGS). The combination of detailed kinetic studies with the measured permeation flux for the Pd-Ag membrane allowed a complete comparison between experimental and simulated operation variables. The variables studied for both catalysts were methane conversion and hydrogen permeation as a function...

British Library Electronic Table of Contents (United Kingdom)

In this study, ethanol organosolv pretreatment was investigated and optimized for the pretreatment of empty palm fruit bunch using (1) response surface methodology based on three-variable central composite design and (2) the combined severity parameters. The reaction parameters studied were sulfuric acid concentration (0.5-2.0%), reaction temperature (160-200^oC) and residence time (45-90min). Both models provide valuable and complementary informations: using combined severity parameters, very good predictions were obtained concerning xylan and lignin extraction whereas central composite design is the best model for glucose production. The optimal values of the variables were as the followings: sulfuric acid 2.0% w/w, 160^oC, 78min and the experimental values (96.0%) concerning glucose and...

Science.gov (United States)

Generalized linear models (GLMs), as defined by J. A. Nelder and R. W. M. Wedderburn (1972), unify a class of regression models for categorical, discrete, and continuous response variables. As an extension of classical linear models, GLMs provide a common body of theory and methodology for some seemingly unrelated models and procedures, such as the logistic, Poisson, and probit models, that are increasingly used in family studies. This article provides an overview of the principle and the key components of GLMs, such as the exponential family of distributions, the linear predictor, and the link function. To illustrate the application of GLMs, this article uses Canadian national survey data to build an example focusing on the number of close friends among older adults. The article concludes with a discussion of the strengths and weaknesses of GLMs.

British Library Electronic Table of Contents (United Kingdom)

In this article we evaluate a US Forest Service plan to mitigate damages from an invasive insect on public, forested land. We develop a dynamic model of infestation and control to explicitly account for biological interactions, baseline conditions, and uncertainty, thus creating a more complete picture of policy impacts than a static cost benefit analysis could provide. We combine the results of the dynamic model with an empirical study of nonmarket forest benefits to create a bioeconomic model of ecosystem management. Estimating the empirical model in a Bayesian framework allows us to treat the economic coefficients of the dynamic model as random variables. We specify distributions for the biological parameters and examine the effects of both biological and economic uncertainty on the pre...

Science.gov (United States)

In the present work we introduce a novel multi-agent model with the aim to reproduce the dynamics of a double auction market at microscopic time scale through a faithful simulation of the matching mechanics in the limit order book. The agents follow a noise decision making process where their actions are related to a stochastic variable, the market sentiment, which we define as a mixture of public and private information. The model, despite making just few basic assumptions over the trading strategies of the agents, is able to reproduce several empirical features of the high-frequency dynamics of the market microstructure not only related to the price movements but also to the deposition of the orders in the book.

UK PubMed Central (United Kingdom)

Resistance (R) protein mediated recognition of pathogen avirulence effectors triggers signaling that induces a very robust form of species-specific immunity in plants. The soybean Rpg1-b protein mediates...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Glacier fluctuations exclusively due to internal variations in the climate system are simulated using downscaled integrations of the ECHAM4/OPYC coupled general circulation model (GCM). A process-based modeling approach using a mass balance model of intermediate complexity and a dynamic ice flow model considering simple shearing flow and sliding are applied. Multi-millennia records of glacier length fluctuations for Nigardsbreen (Norway) and Rhonegletscher (Switzerland) are simulated using auto-regressive processes determined by statistically downscaled GCM experiments. Return periods and probabilities of specific glacier length changes using GCM integrations excluding external forcings such as solar irradiation changes, volcanic or anthropogenic effects are analyzed and compared to historical glacier length records. Preindustrial fluctuations of the glaciers as far as observed or reconstructed, ...

Energy Technology Data Exchange (ETDEWEB)

The aim of this paper is to present and evaluate control strategies for adjustment and preservation of air quality, thermal and visual comfort for buildings' occupants while, simultaneously, energy consumption reduction is achieved. Fuzzy PID, fuzzy PD and adaptive fuzzy PD control methods are applied. The inputs to any controller are: the PMV index affecting thermal comfort, the CO{sub 2} concentration affecting indoor air quality and the illuminance level affecting visual comfort. The adaptive fuzzy PD controller adapts the inputs and outputs scaling factors and is based on a second order reference model. More specifically, the scaling factors are modified according to a sigmoid type function, in such a way that the measured variable to be as closer as possible to the reference model. The adaptive fuzzy PD controller is compared to a non-adaptive fuzzy PD and to an ON-OFF one. The comparison criteria are the ...

International Nuclear Information System (INIS)

A set of equations describing a stress-mediated evolution of the nonequilibrium dopant-defect system has been derived and analyzed. Together with coupled diffusion of dopant atoms and point defects, we consider the drift of all mobile species in different charge states, namely vacancies, self-interstitials, and pairs 'dopant atom-point defect', in the field of stress. It has been shown that stresses may affect the diffusion of dopant atoms mainly in two ways: (1) directly, due to the drift of the pairs in the field of stress; (2) indirectly, by the formation of nonuniform defect distribution due to the drift of point defects. On this basis, various features of doping processes, such as phenomena of 'uphill' impurity diffusion near the surface (within the framework of the first or second mechanisms) and the peculiarities of high concentration phosphorus diffusion (due to the second mechanism), can be explained. Numerical computations of high concentration phosphorus ...

Energy Technology Data Exchange (ETDEWEB)

A reliability approach for probabilistic modeling of one-dimensional non-reactive and reactive transport in porous media provides two important quantitative results: (1) an estimate of the probability that dimensionless concentration equals or exceeds some specified level and, (2) the sensitivity of the probabilistic outcome to likely changes in each uncertain variable. The reliability approach is particularly attractive because it can incorporate various marginal probability density functions (PDF) for any of the uncertain variables. In this work uncertain variables include: groundwater flow velocity, diffusion coefficient, dispersivity, distribution coefficient, porosity and bulk density. The primary objective is to examine how the probabilistic outcome is influenced by choice of marginal PDF, correlation and magnitude of uncertainty for the variables. Because little information ...

British Library Electronic Table of Contents (United Kingdom)

Insect attraction to host plants may be partly mediated by visual stimuli. In the present study, the responses of adult Hycleus apicicornis (Gur.) (Coleoptera: Meloidae) to plant models of different colours, different combinations of two colours, or three hues of blue of different shapes are compared. Single-colour models comprised the colours sky blue, bright green, yellow, red, white and black. Sky blue (reflecting light in the 440-500 nm region) is the most attractive, followed by white, which reflects light over a broader range (400-700 nm). On landing on sky blue targets, beetles exhibit feeding behaviour immediately. When different hues of blue (of different shapes) are compared, sky blue is preferred over turquoise, followed by dark blue, indicating that H. apicicornis is more attra...

British Library Electronic Table of Contents (United Kingdom)

Major forecast errors on the background error covariance from initial conditions, atmospheric forcing, model open boundary conditions, and the river discharges are examined in a coastal model of northern South China Sea. The analysis of background error covariance matrix produced by model ensemble shows that the perturbations of the initial conditions and atmospheric forcing play major roles in producing and maintaining the amplitude of ensemble spread except for the sea surface height (SSH) field. The perturbation of model open boundary conditions can influence ensemble spread of all variables and covariance between temperature and velocity or between temperature and SSH. The perturbation of river discharge mainly affects the covariance of salinity in river estuary. A data assimilation ex...

Energy Technology Data Exchange (ETDEWEB)

Cellulose raw materials costs must be considered in order to obtain a minimized hexose cost. In recognition of this fact, it may be economically advantageous to operate at less than maximum hexose concentration in the reactor and to recycle unreacted cellulose. The objective of this article is to optimize a cellulose-recycle reactor system for producing hexose at minimum cost. A sensitivity analysis of the important variables in the mathematical model of this system is also discussed.

Energy Technology Data Exchange (ETDEWEB)

It is shown that a sufficient condition for a model describing the motion of a particle on a coset space to possess a Fundamental Poisson bracket Relation, and consequently charges in involution, is that it must be a symmetric space. The conditions, a Hamiltonian, or any functions of the canonical variables, has to satisfy in order to commute with these charges, are studied. It is show that, for the case of the noncompact symmetric spaces, these conditions lead to an algebraic structure which lays an important role in the construction of conserved quantities.

Energy Technology Data Exchange (ETDEWEB)

A non-recursive model is proposed and empirically tested with data of opponents of nuclear power. In explaining conventional and unconventional participation the theory of collective action is applied and modified in two respects: the perceived influence on the elimination of collective evils are taken into account; the selective incentives considered are non-material ones. These modifications proved to be valid: the collective good variables and non-material incentives were important determinants for the two forms of participation. Another result was that there is a reciprocal causal relationship between conventional and unconventional participation.

Energy Technology Data Exchange (ETDEWEB)

SYVAC3 (Systems Variability Analysis Code, generation 3) is a computer program that implements a method called systems variability analysis to analyze the behaviour of a system in the presence of uncertainty. This method is based on simulating the system many times to determine the variation in behaviour it can exhibit. SYVAC3 specializes in systems representing the transport of contaminants, and has several features to simplify the modelling of such systems. It provides a general tool for estimating environmental impacts from the dispersal of contaminants. This report describes the use and structure of SYVAC3. It is intended for modellers, programmers, operators and reviewers who deal with simulation codes based on SYVAC3. From this manual they can learn how to link a model with SYVAC3, how to set up an input file, and how to extract results from output files. The manual lists the ...

Energy Technology Data Exchange (ETDEWEB)

This report to the Nuclear Regulatory Commission (NRC) describes the development and application of a methodology to systematically and quantitatively assess predictive uncertainty in groundwater flow and transport modeling that considers the combined impact of hydrogeologic uncertainties associated with the conceptual-mathematical basis of a model, model parameters, and the scenario to which the model is applied. The methodology is based on a n extension of a Maximum Likelihood implementation of Bayesian Model Averaging. Model uncertainty is represented by postulating a discrete set of alternative conceptual models for a site with associated prior model probabilities that reflect a belief about the relative plausibility of each model based on its apparent consistency with available knowledge and ...

Science.gov (United States)

The removal of Reactive Black 5 dye in an aqueous solution by electrocoagulation (EC) as well as addition of flocculant was investigated. The effect of operational parameters, i.e. current density, treatment time, solution conductivity and polymer dosage, was investigated. Two models, namely the artificial neural network (ANN) and the response surface method (RSM), were used to model the effect of independent variables on percentage of dye removal. The findings of this work showed that current density, treatment time and dosage of polymer had the most significant effect on percentage of dye removal (p0.8). PMID:21411950

Energy Technology Data Exchange (ETDEWEB)

This paper proposes an integrated method for using experimental data and CFD modeling to develop engineering correlations for atrium smoke management. Part I focused on the experimental program and validation of a CFD model of the experimental facility. Part II describes the extension of this model to a parametric study of balcony spill plumes. Smoke management in buildings during fire events often uses mechanical ventilation systems to maintain smoke layer elevation above a safe evacuation path. Design of these systems requires accurate correlations for the smoke production or mass flow rate of the buoyant fire plume. One design issue is the mass flow rate of fire plumes which spill out from a fire compartment, under a balcony and up through an atrium or other large volume. Current engineering correlations for these balcony spill plumes (BSPs) are based on a combination of one-tenth scale test data and theoretical ...

Energy Technology Data Exchange (ETDEWEB)

This article proposes a model for estimating the effect of the overall thermal resistance of the absorber and the coolant on a solar thermal energy system utilizing advanced heat transfer mediums. Two equations can be used to model a dynamic system: one for the maximum conversion efficiency and one to specify the constraint that, in quasi-steady state, the net energy collected must be transferred to the coolant. These two equations define a constrained optimization problem in two variables, the fluid and the absorber temperatures. The results present interesting implications for liquid metal, direct absorption, and solar evaporating systems.

Energy Technology Data Exchange (ETDEWEB)

Although incompressible fluid flows can be regarded as a particular case of a general problem, numerical methods and the mathematical formulation aimed to solve compressible and incompressible flows have their own peculiarities, in such a way, that it is generally not possible to attain both regimes with a single approach. In this work, we start from a typically compressible formulation, slightly modified to make use of pressure variables and, through augmenting the stabilising parameters, we end up with a simplified model which is able to deal with a wide range of flow regimes, from supersonic to low speed gas flows. The resulting methodology is flexible enough to allow for the simulation of liquid flows as well. Examples using conservative and pressure variables are shown and the results are compared to those published in the literature, in order to validate the method. (author)

British Library Electronic Table of Contents (United Kingdom)

Native to Southeast Asia, Hygrophila polysperma is an invasive aquatic weed of lotic habitats in the southern United States and Mexico. An increase in the number of water bodies invaded by hygrophila since 1990 suggests that current methods employed to control this weed are inadequate. Classical biological control may be a viable option for long term regulation of hygrophila in the invaded range. In this study, we used the Maximum Entropy Species Distribution Model (MaxEnt) to prioritize climatically suitable native habitats in India and Bangladesh for conducting exploratory surveys to collect biological control agents. In total, 164 point occurrences from the United States and Mexico and 20 predictor variables, including 19 bioclimatic variables and altitude, were used to predict the nati...

Science.gov (United States)

A multivariate bioprocess control approach, capable of tracking a pre-set process trajectory correlated to the biomass or product concentration in the bioprocess is described. The trajectory was either a latent variable derived from multivariate statistical process monitoring (MSPC) based on partial least squares (PLS) modeling, or the absolute value of the process variable. In the control algorithm the substrate feed pump rate was calculated from on-line analyzer data. The only parameters needed were the substrate feed concentration and the substrate yield of the growth-limiting substrate. On-line near-infrared spectroscopy data were used to demonstrate the performance of the control algorithm on an Escherichia coli fed-batch cultivation for tryptophan production. The controller showed good ability to track a defined biomass trajectory during varying process dynamics. The robustness of the control was high, despite ...

International Nuclear Information System (INIS)

A nonlinear mathematical model is presented of a WWER-440 nuclear power plant horizontal steam generator. On the proposed model is based a computer program for investigating transients in steam generators during loss of coolant accidents. Processes taking place at the primary side of the steam generator are described by a set of partial differential equations while those at the secondary side of the steam generator are described by plain differential equations with the variables being complex time functions. The model takes account of the coolant as both a single- and two-phase medium, of changes in the direction of the primary coolant flow and of changes in the direction of heat transfer. Heat transfer through the wall is based on a simple model of heat transfer through a thin-walled tube and includes a correction for the heat resistance of the wall. (author).

British Library Electronic Table of Contents (United Kingdom)

Objectives The optimal timing of pyeloplasty for children diagnosed with ureteropelvic junction obstruction (UPJO) after workup for antenatal hydronephrosis is disputed. We sought to examine the potential costs and clinical outcomes of treatment protocols featuring different indications for pediatric pyeloplasty using Markov models. Methods Cost and outcomes analysis using Markov modeling was performed for three treatment algorithms: medical management, immediate pyeloplasty (during the first year of life), and pyeloplasty after no improvement on imaging. The costs were determined from the perspective of the medical institution. The variables tracked during Markov model simulation included age at resolution of UPJO, the proportion of patients with worsened hydronephrosis, the number of pye...

Energy Technology Data Exchange (ETDEWEB)

Density is useful in deducing the spatial structure of coals. In this paper, nitrogen has been used instead of the commonly employed helium, for the gas displacement pycnometer based density determination of a number of coals of Indian origin. The results show that the nitrogen-based densities are always higher than the helium-based ones. Also, empirical relationships between the helium-based and nitrogen-based coal densities have been developed by two modeling methods, namely, multi-variable regression and artificial neural networks. Although the two models have fared well, the neural network model exhibits a relatively better prediction accuracy and generalization performance than the regression model. This study thus demonstrates that nitrogen, which is cheaper and easily available, can be used gainfully as the probe gas for estimating the true density of coals. 23 refs., 1 fig., ...

KoreaScience (Korea)

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DEFF Research Database (Denmark)

Udgivelsesdato: 2007/7

Norwegian Open Research Archives (NORA)

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CERN Document Server

I review what we know about the donor stars in cataclysmic variables (CVs), focusing particularly on the close link between these binary components and the overall secular evolution of CVs. I begin with a brief overview of the "standard model" of CV evolution and explain why the key observables this model is designed to explain - the period gap and the period minimum -- are intimately connected to the properties of the secondary stars in these systems. CV donors are expected to be slightly inflated relative to isolated, equal-mass main-sequence (MS) stars, and this "donor bloating" has now been confirmed observationally. The empirical donor mass-radius relationship also shows a discontinuity at M_2 = 0.2 M_sun which neatly separates long- and short-period CVs. This is strong confirmation of the basic disrupted magnetic braking scenario for CV evolution. The empirical M_2-R_2 relation can be combined with stellar ...

British Library Electronic Table of Contents (United Kingdom)

The T cell receptor is a fundamental mediator of the adaptive immune responses, since TR ab on T cells recognize foreign structures (peptides derived from processed antigens) bound to the major histocompatibility complex (MHC) on APC cells. In the present study, we report the cloning of six TRB chains cDNA sequences from gilthead sea bream (Sparus aurata), a fish of high economical impact in South Mediterranean aquaculture. The V-BETA domains have the canonical features of known teleost and mammalian TR V-BETA domains and have been divided in four different subgroups. A multiple alignment of the six sea bream TRB chains with other known TRB sequences was assembled and showed the conservation of the four cysteine residues involved in disulphide bonds and of some amino acids with an importan...

British Library Electronic Table of Contents (United Kingdom)

Summary 1.-Traditional views of ecological disturbance emphasize the role that physical disturbances play in reducing competition between populations and maintaining species coexistence. I present an alternative view that employs a simple Lotka-Volterra model to demonstrate how disturbance resistance, disturbance resilience and resource storage can increase competition between individual perennial plants of similar growth form along a resource supply gradient. 2.-In contrasting the growth of individual genets of two hypothetical species, I assumed that traits associated with inherently low module (i.e. plant part) mortality in infertile soils resulted in greater resource storage, but traded off with maximum potential net photosynthesis rates and thus disturbance resilience. 3.-The species ...

Science.gov (United States)

In this dissertation, a two-phase, air-droplets, dilute, turbulent, and steady state flow in a horizontal rectangular channel, is modeled and numerically simulated using a modified KIVA-3V code. The deposition of different sizes of droplets on the walls of the channel is also studied. In this model, the interaction effects between the phases (two-way coupling) are considered by source terms in the momentum and energy equations for the continuous phase and by the instantaneous local velocity of the air in the droplet equation of motion, which includes the aerodynamic and gravitational forces. The turbulence is modeled by a k-? model. The interaction effects between the turbulence and the dispersed droplets are also taken into account. The effects of the turbulence on the droplets are modeled by a fluctuating component added to the local air velocity in the droplet equation of motion. ...

British Library Electronic Table of Contents (United Kingdom)

The need for alternative energy increases steadily???especially due to the climate change and the limited availability of fossil fuels. Geothermal power uses the intrinsic heat which is stored in the accessible part of the Earth???s crust. Its importance among the renewable energy resources originates from the almost unlimited energy supply of the Earth and its independence from external influences such as seasonal or even daily climatic variability. Nevertheless, there are risks which have to be assessed. From a mathematical point of view there are four building blocks of the characterization of deep geothermal systems: seismic exploration, gravimetry, modeling transport processes, and modeling the stress field. In particular, local depletion poses a significant risk during the industrial...

British Library Electronic Table of Contents (United Kingdom)

SummaryA meshless numerical model is proposed to investigate shallow-water dam break flows in 1D open channels. The numerical model is to solve the shallow water equations (SWE) based on smoothed particle hydrodynamics (SPH). The concept of slice water particles (SWP) is adopted in the SPH-SWE formulation. The numerical sensitivity analysis is first performed to study the appropriate SWP number and variable smoothing length through dam break flows in an idealized 1D channel with dry/wet beds. Extensive validation by comparison with laboratory and field data is next conducted for four benchmark problems, including dam break flows through a rough flat channel, a rough bumpy channel with various downstream boundary conditions, a nonprismatic channel, and a realistic scale model of the Toce ri...

Energy Technology Data Exchange (ETDEWEB)

A method of modeling freeze-thaw cycles of naturally deposited snowpacks is presented. The model involves the Stefan condition as an independent governing equation on the exterior moving boundary to calculate snowpack thinning, flow of water through a variably saturated layered porous medium as described by the Richards equation, and heat conduction with a phase change. The heat conduction problem was treated in two ways. Local heat conduction between a snow grain and its surrounding water film was treated by using a simple energy balance. Global heat conduction with a phase change (the Stefan problem) was introduced to calculate the space-time temperature distribution. In order to handle multiple interior moving boundaries, a specific form of the enthalpy formulation was used for heat conduction with a phase change. Changing material properties were considered according to the calculated meltwater refreezing. 48 refs., 11 ...

CERN Document Server

We consider the exact path sampling of the squared Bessel process and some other continuous-time Markov processes, such as the CIR model, constant elasticity of variance diffusion model, and hypergeometric diffusions, which can all be obtained from a squared Bessel process by using a change of variable, time and scale transformation, and/or change of measure. All these diffusions are broadly used in mathematical finance for modelling asset prices, market indices, and interest rates. We show how the probability distributions of a squared Bessel bridge and a squared Bessel process with or without absorption at zero are reduced to randomized gamma distributions. Moreover, for absorbing stochastic processes, we develop a new bridge sampling technique based on conditioning on the first hitting time at zero. Such an approach allows us to simplify simulation schemes. New methods are illustrated with pricing ...

Energy Technology Data Exchange (ETDEWEB)

The dynamical effects of spatially homogeneous electromagnetic fields on anisotropic Bianchi type-IX models are studied. The Lagrangians and Hamiltonians affecting the evolution of anisotropy (including the gravitational and electromagnetic potentials) are obtained for very general spatially homogeneous metrics by means of the Arnowitt-Deser-Misner Hamiltonian formalism. For models having diagonal metrics an exact solution for the electromagnetic fields is obtained. This solution allows a qualitative solution for the gravitational variables. The total solution is similar to that of Brill. For Bianchi type-IX models having symmetric and general metrics, a discussion of the qualitative behavior of the universe point under the influence of the above potentials is given. In particular, it is shown that in some cases the presence of the electromagnetic potential inhibits some types of singularities.

British Library Electronic Table of Contents (United Kingdom)

The battery size of a Plug-in Hybrid Electric Vehicle (PHEV) is decisive for the electrical range of the vehicle and crucial for the cost-effectiveness of this particular vehicle concept. Based on the energy consumption of a conventional reference car and a PHEV, we introduce a comprehensive total cost of ownership model for the average car user in Germany for both vehicle types. The model takes into account the purchase price, fixed annual costs and variable operating costs. The amortization time of a PHEV also depends on the recharging strategy (once a day, once a night, after each trip), the battery size, and the battery costs. We find that PHEVs with a 4kWh battery and at current lithium-ion battery prices reach the break-even point after about 6 years (5 years when using the lower nig...

Science.gov (United States)

High performance sorbents for flue gas desulfurization can be synthesized by hydration of coal fly ash, calcium sulfate, and calcium oxide. In general, higher desulfurization activity correlates with higher sorbent surface area. Consequently, a major aim in sorbent synthesis is to maximize the sorbent surface area by optimizing the hydration conditions. This work presents an integrated modeling and optimization approach to sorbent synthesis based on statistical experimental design and two artificial intelligence techniques: neural network and genetic algorithm. In the first step of the approach, the main and interactive effects of three hydration variables on sorbent surface area were evaluated using a full factorial design. The hydration variables of interest to this study were hydration time, amount of coal fly ash, and amount of calcium sulfate and the levels investigated were 4-32 h, 5-15 g, and 0-12 g, respectively. In ...

International Nuclear Information System (INIS)

We present a description of the ground state and low-lying excited states of two holes in the 4x4 cluster t-J model in terms of a simple model for the motion of a single bipolaron. The existence of short-range antiferromagnetic correlations has been assumed. According to the suggested scenario, the formation of the bipolaron is mediated by the reduction of the magnetic energy in the case of two holes occupying nearest neighbor sites. The relevant part of the Hilbert space consists of wave functions corresponding to holes oscillating around pairs of nearest neighbor sites and trapped in a potential well due to strings of spin defects. Virtual processes which connect these states involve both the kinetic term and the transverse part of the Heisenberg Hamiltonian. Many properties of energy level schemes obtained by numerical diagonalizations such as the sequence of the lowest states for each irreducible representation of the k ...

Energy Technology Data Exchange (ETDEWEB)

Attention deficit disorder (ADHD) is a complex biobehavioral phenotype which affects up to 8% of the general population and often impairs social, academic, and job performance. Its origins are heterogeneous, but a significant genetic component is suggested by family and twin studies. The murine strain, coloboma, displays a spontaneously hyperactive phenotype that is responsive to dextroamphetamine and has been proposed as a genetic model for ADHD. Coloboma is a semi-dominant mutation that is caused by a hemizygous deletion of the SNAP-25 and other genes on mouse chromosome 2q. To test the possibility that the human homolog of the mouse coloboma gene(s) could be responsible for ADHD, we have carried out linkage studies with polymorphic markers in the region syntenic to coloboma (20p11-p12). Five families in which the pattern of inheritance of ADHD appears to be autosomal dominant were studied. Segregation analysis of the traits studied suggested that the best ...

DEFF Research Database (Denmark)

Udgivelsesdato: 1995-Nov

CERN Document Server

Extracting useful information from high-dimensional data is an important focus of today's statistical research and practice. Penalized loss function minimization has been shown to be effective for this task both theoretically and empirically. With the virtues of both regularization and sparsity, the $L_1$-penalized squared error minimization method Lasso has been popular in regression models and beyond. In this paper, we combine different norms including $L_1$ to form an intelligent penalty in order to add side information to the fitting of a regression or classification model to obtain reasonable estimates. Specifically, we introduce the Composite Absolute Penalties (CAP) family, which allows given grouping and hierarchical relationships between the predictors to be expressed. CAP penalties are built by defining groups and combining the properties of norm penalties at the across-group and within-group levels. Grouped selection occurs for ...

Energy Technology Data Exchange (ETDEWEB)

Consideration of the technical feasibility of Yucca Mountain in Nevada as the site for a high-level nuclear waste repository has led to an intense debate regarding the economic, social, and political impacts of the repository. Impediments to the siting process mean that the nuclear waste problem is being resolved by adhering to the status quo, in which nuclear waste is stored at scattered sites near major population centers. To assess the merits of alternative siting strategies--including both the permanent repository and the status quo- we consider the variables that would be included in a model designed to select (1) the optimal number of disposal facilities, (2) the types of facilities (e.g., permanent repository or monitored retrievable facility), and (3) the geographic location of storage sites. The objective function in the model is an all-inclusive measure of social cost. The intent of the exercise is not to ...

Energy Technology Data Exchange (ETDEWEB)

We discuss strictly efficient models for measurement-based quantum computing using physical continuous variables, such as field modes of light. Such measurement-based quantum computing (MBQC) provides a promising paradigm for quantum computation as it does not require performing unitary gates during the computation, but rather appropriate readout. Here, we introduce novel schemes for which the resource state can be reasonably and efficiently prepared, and which notably do not require having infinite squeezing or mean energy available. What is more, error correction techniques are implementable, as the logical information is stored in finite-dimensional objects grasping correlations of the quantum states. Using the ideas of computational tensor networks we discuss how to sequentially prepare suitable physical resource states with cavity QED or with non-linear optics and how to efficiently implement a computational universal set of quantum ...

Energy Technology Data Exchange (ETDEWEB)

A mathematical model was developed to predict the penetration of a transient fuel spray, the temporal and spatial distribution of air-fuel mixture before the end of ignition delay and the subsequent pressure rise during combustion in a Direct-Injection Diesel Engine with and without swirl. The model accounts for the non-isothermal and non-isobaric character of processes during fuel injection resulting from continuous motion of the piston. The effects of various engine operating variables on spray were studied and graphically presented. The calculated spray penetration with and without crossflow of air is compared with the available experimental data of other researchers with good agreement. The model can predict the rate of combustible-mixture formation, the rate of heat release and cylinder pressure as a function of time in direct injection (DI) diesel engine. A single-cylinder D.I. research diesel ...

Energy Technology Data Exchange (ETDEWEB)

The atmosphere and the biosphere are inherently coupled to one another. Atmospheric surface state variables such as temperature, winds, water vapor, precipitation, and radiation control biophysical, biogeochemical, and ecological processes at the surface and subsurface. At the same time, surface fluxes of momentum, moisture, heat, and trace gases act as time-dependent boundary conditions providing feedback on atmospheric processes. To understand such phenomena, a coupled set of interactive models is required. Costs are still prohibitive for computing surface/subsurface fluxes directly for medium-resolution atmospheric general circulation models (AGCMs), but a technique has been developed for testing large-scale homogeneity and accessing surface parameterizations and models to reduce this computational cost and maintain accuracy. This modeling system potentially bridges the observed ...

Science.gov (United States)

The simultaneous diffusion of Si and the dopants B, P, and As has been studied by the use of a multilayer structure of isotopically enriched Si. This structure, consisting of 5 pairs of 120 nm thick natural Si and {sup 28}Si enriched layers, enables the observation of {sup 30}Si self-diffusion from the natural layers into the {sup 28}Si enriched layers, as well as dopant diffusion from an implanted source in an amorphous Si cap layer, via Secondary Ion Mass Spectrometry (SIMS). The dopant diffusion created regions of the multilayer structure that were extrinsic at the diffusion temperatures. In these regions, the Fermi level shift due to the extrinsic condition altered the concentration and charge state of the native defects involved in the diffusion process, which affected the dopant and self-diffusion. The simultaneously recorded diffusion profiles enabled the modeling of the coupled dopant and self-diffusion. From the modeling of the ...

International Nuclear Information System (INIS)

The structure functions (SF) of nuclei determined within the framework of the flucton model with rescaling (FMR) are compared with new experimental data of the ITEP on cumulative #pi#-meson yield in a wide range of the scale variable X (1

CERN Document Server

We give a general local central limit theorem for the sum of two independent random variables, one of which satisfies a central limit theorem while the other satisfies a local central limit theorem with the same order variance. We apply this result to various quantities arising in stochastic geometry, including: size of the largest component for percolation on a box; number of components, number of edges, or number of isolated points, for random geometric graphs; covered volume for germ-grain coverage models; number of accepted points for finite-input random sequential adsorption; sum of nearest-neighbour distances for a random sample from a continuous multidimensional distribution.

International Nuclear Information System (INIS)

The high-spin states in transitional odd-mass nuclei are studied in terms of an odd quasi-particle coupled to an asymmetric rotor with a variable moment of inertia (VMI). In order to take into account the VMI, the basis states are expanded in terms of the core eigenfunctions. Excitation energies, quadrupole moments, magnetic moments, B(E2) values and B(M1) values are calculated and compared with the experimental data for nuclei in Au and La regions. On comparison with other descriptions it is found that the treatment with VMI provides a more satisfactory explanation of the data. (Auth.).

International Nuclear Information System (INIS)

Purpose: The purpose of this study was to evaluate the efficacy and toxicity of replication-competent adenovirus-mediated double suicide gene therapy in an adjuvant setting with external beam radiation therapy (EBRT) in an experimental prostate cancer model in preparation for a Phase I clinical study in humans. Methods: For efficacy studies, i.m. DU145 and intraprostatic LNCaP C4-2 tumors were established in immune-deficient mice. Tumors were injected with the lytic, replication-competent Ad5-CD/TKrep adenovirus containing a cytosine deaminase (CD)/herpes simplex virus thymidine kinase (HSV-1 TK) fusion gene. Two days later, mice were administered 1 week of 5-fluorocytosine + ganciclovir (GCV) prodrug therapy and fractionated doses of EBRT (trimodal therapy). Tumor control rate of trimodal therapy was compared to that of EBRT alone. For toxicology studies, immune-competent male mice received a single intraprostatic injection (10"1"0 vp) of the ...

Energy Technology Data Exchange (ETDEWEB)

This interim technical report presented a summary of results obtained from Pit Lake models developed from different simulation models. The models were used to predict stratification in a hypothetical Pit Lake. Predictions were used to assess the hydrodynamic similarities and differences between the 2 models and to determine if the models would produce similar stratification profiles for the Pit Lakes to previous models. Results showed that the models produced similar results for both temperatures and salinities. The main difference between the RMA10 and CE-QUAL-W2 model used in a previous study was found to be run time. A sensitivity analysis of the RMA10 and CE-QUAL-W2 model predictions was completed to assess the effects of segmentation; time step; lake surface area; lake orientation; and ...

UK PubMed Central (United Kingdom)

AimsIt is unclear as to which mediators are involved in mediating the response to nasal mannitol challenge, a novel osmotic stimulus.MethodsA...Full Text Available

UK PubMed Central (United Kingdom)

The phytochrome-mediated attachment of root tips of mung bean (Phaseolus aureus) and barley (Hordeum vulgare) to glass is affected by the prior exposure of hydrated...Full Text Available

UK PubMed Central (United Kingdom)

Autoimmune cholangitis would be the appropriate name to define the immune-mediated bile duct injury following the breakdown of tolerance to mitochondrial proteins and the appearance of serum autoantibodies...Full Text Available

UK PubMed Central (United Kingdom)

In chronic kidney disease, fibroblast dysfunction causes renal fibrosis and renal anemia. Renal fibrosis is mediated by the accumulation of myofibroblasts, whereas renal anemia is mediated by the reduced...Full Text Available

UK PubMed Central (United Kingdom)

IntroductionTyrosine phosphorylated signal transducer and activator of transcription 3 (pStat3) is expressed in numerous cancers and is required for mediating tumorigenesis. Autocrine...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundThe emergence of plasmid-mediated carbapenemases, such as NDM-1 in Enterobacteriaceae is a major public health issue. Since they mediate resistance to...Full Text Available

Science.gov (United States)

In drug development, Caco-2 cells are often employed to study the influence of membrane transporters on drug permeability. The aim of the current study was to characterize permeability and kinetic parameters of selected organic anionic compounds in Caco-2 cells, and to investigate whether the Caco-2 cell line may be used as an overall model to predict interactions on multiple membrane transporters in the intestine. Taurocholic acid (TCA) and estrone-3-sulfate (E(1) S) were used as model substrates. Possible inhibitors studied were TCA, E(1) S, taurolithocholic acid, fluvastatin, and glipizide. The effects of these compounds on initial uptake, apparent permeability, and intracellular end-point accumulations of the probe substrates were studied. Both interactions on apical and basolateral influx transporters were observed. These interactions were proposed to be mediated mainly by the apical sodium-dependent bile acid ...

Science.gov (United States)

Radon-222 was shown to be useful in-situ tracer for studying thermodynamic, geologic, and transport properties of geothermal reservoirs. The relationships to reservoir properties are based on steady-state and non-steady-state models which incorporate the thermodynamic state and relative mobility of the fluids, and partitioning between the fluid phases. The steady-state thermodynamic models assume equilibrium between radon emanation from the reservoir rock and the geofluid concentration. The non-steady-state model solves the partial differential equations describing radon transport under transient two-phase geothermal flow conditions. Radon concentrations of fluids from nine geothermal reservoirs showed strong correlations to the specific volume of the reservoir fluid. Lowest values were associated with all-liquid wells at Cerro Prieto, Wairakei, and Los Azufres reservoirs, and the highest values for steady-producing wells ...

KoreaScience (Korea)

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KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

Crenarchaea are ubiquitous and abundant microbial constituents of soils, sediments, lakes and ocean waters, yet relatively little is known about their fundamental evolutionary, ecological, and physiological properties. To better describe the ubiquitous nonthermophilic Crenarchaea, we analyzed the genome sequence of one representative, the uncultivated sponge symbiont, Cenarchaeum symbiosum. C. symbiosum genotypes coinhabiting the same host partitioned into two dominant populations, corresponding to previously described a- and b-type ribosomal RNA variants. Although synthetic, overlapping a- and b-type ribotypes harbored significant genetic variability. A single tiling path comprising the dominant a-type genotype was assembled, and used to explore the biological properties of C. symbiosum and its planktonic relatives. Out of a total of 2,066 predicted open reading frames, 36% were more highly conserved with other Archaea. The remainder partitioned between bacteria ...

Energy Technology Data Exchange (ETDEWEB)

Due to deregulation, the electrical power industry is undergoing deep changes, moving towards an open market. Two kinds of parties are active in the new environment: the economical agents (producers, consumers, brokers) and the power system operator, the former interested in power exchanges and their economic value, the latter in bus injections and their threat to the security of the transmission network. The variables used to model the transmission network operation have to be meaningful to the power system operator as well as to the economical parties; the action rules followed by the power system operator to enforce network security have to be carefully designed to be equitable and non-discriminatory. In this paper, a modeling of the power exchanges is proposed in the form of multilateral trades, and some rules for the action of the power system operator are proposed and discussed. The results obtained on a simple study ...

British Library Electronic Table of Contents (United Kingdom)

The oxidation of n-butylbenzene was studied in a jet-stirred reactor (JSR) at 10atm in dilute conditions providing new experimental results over the low- and high-temperature range 550-1180K, and variable equivalence ratio (0.25ϕ1.5). They consisted of concentration profiles of the reactants, stable intermediates and final products, measured as a function of temperature, at a constant residence time of 1s, by sonic probe sampling followed by on-line GC-MS and off-line GC-TCD-FID and GC-MS analyses. The oxidation of n-butylbenzene in these conditions was modeled using a detailed chemical kinetic reaction mechanism (404 species and 2210 reactions, most of them reversible) deriving from a previous scheme proposed for the ignition, oxidation, and combustion of simple aromatics (benzene,...

British Library Electronic Table of Contents (United Kingdom)

The flexibility of bus rapid transit (BRT) in scheduling is one of the greatest differences with traditional buses. In order to improve BRT operation quality, the paper studied the headway optimization and scheduling combination of BRT vehicles. A model has been established to minimize passengers travel costs and vehicles operation cost, and constraints included passenger volume, time, and frequency. The scheduling combination was composed by normal, zone, and express scheduling. The model was solved by genetic algorithm of variable-length coding. The result of the numerical case shows that: the optimization results can save 69.92% cost. The sensitivity analysis shows that, under higher traffic volume or lower speed, the travel cost can be reduced through reasonable scheduling combination....

British Library Electronic Table of Contents (United Kingdom)

The paper deals with the reliability-based design optimization (RBDO) of a riser support installed on a floating production storage and offloading (FPSO) unit under operation, extreme, damaged, and one line failure cases and installation loading conditions. The optimization problem is formulated such that probabilistic thickness variables described with random characteristics are determined by minimizing the weight of the riser support structure subjected to stress constraints for the given target reliability. The initial design model is generated based on actual FPSO riser support specifications. The finite element analysis is conducted using NASTRAN, and the probabilistic optimal solutions are obtained via the moving least squares method in the context of RBDO using a response surface me...

British Library Electronic Table of Contents (United Kingdom)

The purpose of this study was to examine the accuracy of the SW-701 (Yamax Corporation, Tokyo, Japan) and NL-800 (New-Lifestyles, Inc., Lee's Summit, Missouri, USA) pedometer in fifth-grade students while walking, skipping, galloping, sliding, and hopping. Counts registered by both pedometer models were significantly lower than actual counts while skipping, galloping, and sliding, and counts from the NL-800 were significantly lower than the SW-701 during these same movements. No significant differences in step counts were detected between actual counts and the SW-701 and between the pedometer models while walking and hopping; however, the NL-800 registered counts significantly higher than actual counts while hopping. Bland-Altman plots suggest the greatest variability occurred while skippi...

CERN Document Server

We study a stochastic gossip model of continuous opinion dynamics in a society consisting of two types of agents: regular agents, who update their beliefs according to information that they receive from their social neighbors; and stubborn agents, who never update their opinions and might represent leaders, political parties or media sources attempting to influence the beliefs in the rest of the society. When the society contains stubborn agents with different opinions, opinion dynamics never lead to a consensus (among the regular agents). Instead, beliefs in the society almost surely fail to converge, and the belief of each regular agent converges in law to a non-degenerate random variable. The model thus generates long-run disagreement and continuous opinion fluctuations. The structure of the social network and the location of stubborn agents within it shape opinion dynamics. When the society is ``highly fluid'', meaning ...

British Library Electronic Table of Contents (United Kingdom)

This study assessed the impact of the results of genetic testing for hereditary cancer from a multifactorial health psychology perspective, considering that emotional expression plays a key role in psychological adjustment. Measures of dispositional and transactional coping strategies, anxiety and alexithymia were filled out by 77 participants in a longitudinal study design. Statistical analyses were performed using general linear models and partial least squares path modelling, low-constraint methods that are particularly useful in the behavioural sciences. While anxiety levels prior to the result announcement were predictive of the distress experienced by noncarriers, considerable variability was observed for mutation carriers. Some subjects who had lower anxiety levels before the test d...

CERN Document Server

The nature of the `inner engine' that accelerate and collimate the relativistic flow at the cores of GRBs is the most interesting current puzzle concerning GRBs. Numerical simulations have shown that the internal shocks' light curve reflects the activity of this inner engine. Using a simple analytic toy model we clarify the relations between the observed $ \\gamma $-rays light curve and the inner engine's activity and the dependence of the light curves on the inner engine's parameters. This simple model also explains the observed similarity between the observed distributions of pulses widths and the intervals between pulses and the correlation between the width of a pulse and the length of the preceding interval. Our analysis suggests that the variability in the wind's Lorentz factors arises due to a modulation of the mass injected into a constant energy flow.

British Library Electronic Table of Contents (United Kingdom)

Summary 1. A primary goal of evolutionary ecology is to understand factors selecting for the diversity of life histories. Life-history components, such as time-to-reproduction, adult survivorship and fecundity, might differ among species because of variation in direct and indirect benefits of these life histories in different environments or might have lower-than-expected variability because of phylogenetic constraints. Here, we present a phylogenetic examination of demography and life histories using a data base of 204 terrestrial plant species. 2. Overall, statistical models without phylogeny were preferred to models with phylogeny for vital rates and elasticities, suggesting that they lacked phylogenetic signal and are evolutionarily labile. However, the effect of phylogeny was signific...

Energy Technology Data Exchange (ETDEWEB)

This paper describes the structure of dynamic neuronal ensembles (DNEs). DNEs represent a new paradigm for learning, based on biological neural networks that use variable structures. We present a computational neural element that demonstrates biological neuron functionality such as neurotransmitter feedback absolute refractory period and multiple output potentials. More specifically, we will develop a network of neural elements that have the ability to dynamically strengthen, weaken, add and remove interconnections. We demonstrate that the DNE is capable of performing dynamic modifications to neuron connections and exhibiting biological neuron functionality. In addition to its applications for learning, DNEs provide an excellent environment for testing and analysis of biological neural systems. An example of habituation and hyper-sensitization in biological systems, using a neural circuit from a snail is presented and discussed. This paper provides an insight into ...

British Library Electronic Table of Contents (United Kingdom)

In this study, bacterial strains were investigated in order to determine their heavy metal tolerance. The bacterial strains were identified as Bacillus cereus and Bacillus pumilus. In the batch system, the effects of operating variables such as solution pH, initial metal concentration, contact time, and adsorbent dosage were investigated. Both isolates were highly resistance to copper and lead in comparison with the control strain examined. The adsorption capacities of B. cereus and B. pumilus were found to be 22.1mg/g and 28.06mg/g, respectively. The biosorption follows pseudo-second order kinetics and the isotherm fits well to the Langmuir isotherm model. In column experiments, the biosorption was fitted well by the Thomas model. The breakthrough and exhaustion capacity of each biosorben...

Energy Technology Data Exchange (ETDEWEB)

Coupled modeling of subsurface multiphase fluid and heat flow, solute transport and chemical reactions can be used for the assessment of acid mine drainage remediation, mineral deposition, waste disposal sites, hydrothermal convection, contaminant transport, and groundwater quality. Here they present a numerical simulation model, TOUGHREACT, which considers non-isothermal multi-component chemical transport in both liquid and gas phases. A wide range of subsurface thermo-physical-chemical processes is considered. The model can be applied to one-, two- or three-dimensional porous and fractured media with physical and chemical heterogeneity. The model can accommodate any number of chemical species present in liquid, gas and solid phases. A variety of equilibrium chemical reactions is considered, such as aqueous complexation, gas dissolution/exsolution, cation exchange, and surface complexation. Mineral ...

Science.gov (United States)

The performance of intermolecular potential models on the adsorption of benzene on graphitized thermal carbon black at various temperatures is investigated. Two models contain only dispersive sites, whereas the other two models account explicitly for the dispersive and electrostatic sites. Using numerous data in the literature on benzene adsorption on graphitized thermal carbon black at various temperatures, we have found that the effect of surface mediation on interaction between adsorbed benzene molecules must be accounted for to describe correctly the adsorption isotherm as well as the isosteric heat. Among the two models with partial charges tested, the WSKS model of Wick et al. that has only six dispersive sites and three discrete partial charges is better than the very expensive all-atom model of Jorgensen and Severance. Adsorbed ...

Science.gov (United States)

The advancement of bioprocess monitoring will play a crucial role to meet the future requirements of bioprocess technology. Major issues are the acceleration of process development to reduce the time to the market and to ensure optimal exploitation of the cell factory and further to cope with the requirements of the Process Analytical Technology initiative. Due to the enormous complexity of cellular systems and lack of appropriate sensor systems microbial production processes are still poorly understood. This holds generally true for the most microbial production processes, in particular for the recombinant protein production due to strong interaction between recombinant gene expression and host cell metabolism. Therefore, it is necessary to scrutinise the role of the different cellular compartments in the biosynthesis process in order to develop comprehensive process monitoring concepts by involving the most significant process variables and their ...

Science.gov (United States)

A unified Nonhydrostatic Multiscale Model on the Arakawa B grid (NMMB) designed for a broad range of spatial and temporal scales has been under development within the Earth System Modeling Framework (ESMF) at the National Centers for Environmental Prediction (NCEP) as a part of the new National Environmental Modeling System (NEMS). The model follows the general modeling philosophy of the NCEP's WRF NMM grid-point regional dynamical core. The model uses the regular latitude-longitude grid for the global domain, and a rotated latitude-longitude grid in regional applications. The nonhydrostatic component of the model dynamics is introduced through an add-on module that can be turned on or off depending on resolution. The "isotropic" quadratic conservative finite-volume horizontal differencing employed in the model conserves ...

Energy Technology Data Exchange (ETDEWEB)

The control problem associated to a class of horizontal-axis fixed-pitch variable-speed low-power wind energy conversion systems, working in the partial load region, consisting in the energy conversion maximization, is approached here under the assumption that the wind turbine model and its parameters are poorly known. Using a new approach derived from the optimum seeking methods category, generically called Maximum Power Point Tracking (MPPT), the proposed control solution aims at driving the average position of the operating point near to optimality. Instead of inducing sinusoidal search signals, the wind turbulence is here used as search disturbance. The high-speed shaft's average rotational speed is slowly adjusted using the Fast Fourier Transform processing of some available measures from the system as an estimate of the operating point's position/distance to optimality. Numerical simulations are used for preliminary ...

CERN Document Server

We report results of the 2006 April multi-wavelengths campaign of SS 433, focusing on X-ray data observed with Suzaku at two orbital phases (in- and out-of- eclipse) and simultaneous optical spectroscopic observations. By analyzing the Fe25 K_alpha lines originating from the jets, we detect rapid variability of the Doppler shifts, dz/dt ~ 0.019/0.33 day^-1, which is larger than those expected from the precession and/or nodding motion. This phenomenon probably corresponding to "jitter" motions observed for the first time in X-rays, for which significant variability both in the jet angle and intrinsic speed is required. From the time lag of optical Doppler curves from those of X-rays, we estimate the distance of the optical jets from the base to be ~(3-4) \\times 10^14 cm. Based on the radiatively cooling jet model, we determine the innermost temperature of the jets to be T_0 = 13 +/- 2 keV and 16 +/- 3 keV (the average of ...

Science.gov (United States)

The dynamical factors controlling the mean state and variability of the east Pacific intertropical convergence zone (ITCZ) and the associated cross-equatorial boundary layer flow are investigated using observations from the East Pacific Investigation of Climate (EPIC2001) project. The tropical east Pacific exhibits a southerly boundary layer flow that terminates in the ITCZ. This flow is induced by the strong meridional sea surface temperature (SST) gradient in the region. Away from the equator and from deep convection, it is reasonably well described on a day-to-day basis by an extended Ekman balance model. Variability in the strength and northward extent of this flow is caused by variations in free-tropospheric pressure gradients that either reinforce or oppose the pressure gradient associated with the SST gradient. These free-tropospheric gradients are caused by easterly waves, tropical cyclones, and the Madden Julian ...

Energy Technology Data Exchange (ETDEWEB)

This report is the conclusion of a three-part series that describes and attempts to explain regional coal quality variations within the foothills/mountains region of Alberta. Proximate and ultimate analysis variables, plus some vitrinite reflectance and maceral analyses, are examined for the Jurassic-Lower Cretaceous Kootenay Group, Lower Cretaceous Luscar Group, the Lower Paleocene Coalspur Formation, and the Upper Paleocene Obed-Marsh coal-bearing units. The study has two major components: a statistical analysis and mapping of coal quality data provided by the Energy Resources Conservation Board; and a 'geologic models' section, in which regional and local in-seam coal quality variations are examined from a geological perspective. The first component is designed to describe, characterize, and set limits for the coal quality variables, while the second component should provide from a geological ...

British Library Electronic Table of Contents (United Kingdom)

In this paper, the effects of surface mediation on the adsorption isotherm and isosteric heat of adsorption on a graphite surface were investigated, as the surface mediation is known to affect the intermolecular interaction of adsorbed molecules close to the surface. Kim and Steele (Phys. Rev. B 45 (11) (1992) 6226-6233) and others have assumed that the surface mediation is confined only to the first layer. This will be tested in this paper with a combined experimental and Grand Canonical Monte Carlo (GCMC) simulation of adsorption of argon on graphitized thermal carbon black (GTCB) over a range of temperatures (77-95.25K). By matching the simulation results against the experimental data, we have found that the surface mediation is extended up to the fourth layer, rather than only the firs...

Energy Technology Data Exchange (ETDEWEB)

A characteristic of filled elastomers is their ability to undergo very large deformations without damaging their internal structure. The material behaviour is mainly elastic, however, elastomers show hysteresis effects leading to damping properties, which are quite important as regards their applications in various fields of mechanical engineering.A series of experiments (tension, torsion and combinations of both) was carried out on cylindrical bars made of a carbon-black filled rubber mixture. In addition to a pronounced nonlinear rate-dependence, relaxation and viscosity properties are observed as being influenced by the process histories.The behaviour of elastomeric materials is modelled on the basis of a free energy function and evolution equations for additional internal variables. Incorporating or disregarding the very small rate-independent hysteresis, the constitutive modelling may be classified under ...

Energy Technology Data Exchange (ETDEWEB)

Simplifying hypotheses are required when combustion and aerodynamic phenomena are considered simultaneously. In this paper, a turbulent combustion model is proposed, in which the combustion chemistry is reduced to a single reaction. In this way, only two variables are needed to describe the problem and combustion can be characterized by the consumption of one of the two reactive species. In a first step, the instantaneous consumption rate is obtained using the Lagrangian form of the mass fraction equation of the species under consideration, and by considering the equilibrium state only. This state is determined in order to preserve the consistency with results that should be obtained using a complete kinetics scheme. In a second step, the average rate is determined using the instantaneous consumption term and a probabilistic density function. This model was tested on various configurations and in particular on an ...

Energy Technology Data Exchange (ETDEWEB)

This paper describes the comprehensive modeling method of fluid and heat flows in the hydrological system. Based upon the concept that the hydrological system is composed of the air-water 2-phase fluids, and the rock phase, various natural processes are modeled including surface/subsurface 2-phase mass transfer, heat exchanges between fluid phases, between fluid and solid phases, and sensible/latent heat exchanges on the ground surface. A field-oriented numerical simulator is developed, in which a set of governing equations is solved for different variables on the surface and in subsurface regions, respectively. Results of an experimental study are presented, in which transient formulation of heat exchange between fluid/solid phases is examined through matching of the observation and calculated performances. (author)

Energy Technology Data Exchange (ETDEWEB)

An analysis on landscape level was performed to investigate the growth of Scots pine stands (Pinus sylvestris L.) in the research area of 'Duebener Heide' under the impact of rapidly changing pollution loads and to evaluate their further development. Central to the work was a spatial database, installed using a geographic information system (GIS). This database enabled the statistical analysis of relationships and correlations between the growth of the pine stands, the influence of pollution impacts and the natural site characteristics. The results of emission and immission modelling gave detailed evaluation of the pollution load over the investigated area. The spatial information database was linked with a process-based growth model called FORSANA. The resulting regional model was used to simulate forest growth on stand level for variable time periods. The plausibility of the ...

Energy Technology Data Exchange (ETDEWEB)

A contamination event in a water distribution system can result in adverse health impacts to individuals consuming contaminated water from the system. Assessing impacts to such consumers requires accounting for the timing of exposures of individuals to tap-water contaminants that have time-varying concentrations. Here we present a probabilistic model for the timing of ingestion of tap water that we developed for use in the U.S. Environmental Protection Agency's Threat Ensemble Vulnerability Assessment and Sensor Placement Tool, which is designed to perform consequence assessments for contamination events in water distribution systems. We also present a statistical analysis of the timing of ingestion activity using data collected by the American Time Use Survey. The results of the analysis provide the basis for our model, which accounts for individual variability in ingestion timing and provides a series of ...

Energy Technology Data Exchange (ETDEWEB)

Dynamic Flowgraph Methodology (DFM) is a methodological approach to modeling and analyzing the behavior of software-driven embedded systems for the purpose of reliability/safety assessment and verification. The methodology has two fundamental goals: (a) to identify how certain postulated events may occur in a system and (b) to identify an appropriate testing strategy based on an analysis of system functional behavior. To achieve these goals, the methodology employs a modeling framework in which system models are developed in terms of causal relationships between physical variables and temporal characteristics of the execution of software modules. These models are then analyzed to determine how a certain state (desirable or undesirable) can be reached. This is done by developing timed fault trees, which take the form of logical combinations of static trees relating system parameters ...

Energy Technology Data Exchange (ETDEWEB)

The uncertainty associated with the sorption coefficient, or K{sub d} value, is one of the key uncertainties in estimating risk associated with burying low-level nuclear waste in the subsurface. The objective of this study was to measure >648 K{sub d} values and provide a measure of the range and distribution (normal or log-normal) of radionuclide K{sub d} values appropriate for the E-Area disposal site, within the Savannah River Site, near Aiken South Carolina. The 95% confidence level for the mean K{sub d} was twice the mean in the Aquifer Zone (18-30.5 m depth), equal to the mean for the Upper Vadose Zone (3.3-10 m depth), and half the mean for the Lower Vadose Zone (3.10-18 m depth). The distribution of K{sub d} values was log normal in the Upper Vadose Zone and Aquifer Zone, and normal in the Lower Vadose Zone. To our knowledge, this is the first report of natural radionuclide Kd variability in the literature. Using ranges and distribution coefficients ...

Science.gov (United States)

Prairie (Microtus ochrogaster) and meadow voles (M. pennsylvanicus) are closely related species that differ in life strategy and social behaviors, and thus provide an excellent comparative model for the study of neuronal and hormonal mechanisms underlying behavior. In the present study using the elevated plus maze (EPM) test, we found that male prairie voles entered the open arms of the EPM more and remained there longer, and showed a higher level of overall locomotor activity than did male meadow voles. In addition, two weeks of social isolation induced an increase in open arm entries in prairie, but not meadow, voles. Prairie voles also had a higher level of circulating corticosterone compared to meadow voles, and the EPM test increased circulating corticosterone in prairie voles. Finally, social isolation coupled with the EPM test influenced Fos-immunoreactive expression in several brain areas, including the medial preoptic area, ventromedial hypothalamus, ...

Energy Technology Data Exchange (ETDEWEB)

We discuss recent results obtained for the heavy-fermion metals UPd{sub 2}Al{sub 3} and YbRh{sub 2}Si{sub 2}. UPd{sub 2}Al{sub 3} is the first among all superconductors for which tunneling and inelastic neutron-scattering data highlight a non-phononic, i.e., magnetic-exciton mediated, pair state. YbRh{sub 2}Si{sub 2} represents a model system exhibiting pronounced non-Fermi liquid effects above a weak antiferromagnetic phase transition at T{sub N}=70 mK. Upon approaching the quantum critical point (T{sub N}{yields}0), by low doping with Ge, one observes for T<0.3 K disparate behavior in the temperature dependences of both the electrical resistivity and the electronic specific heat as well as a Curie-Weiss law in the uniform magnetic susceptibility, implying uncompensated large 4f moments. These observations indicate a break up of the composite quasiparticles into their local f-spin and itinerant conduction-electron parts.

International Nuclear Information System (INIS)

The effect of nutrition on reproductive performance was studied in a series of experiments using two models. Increased supply of nutrients was based on feeding lupin grain as a supplement and measurements of testicular growth or ovulation rates were used to measure reproductive characteristics. Purified sources of protein and energy were provided to determine the macronutrient(s), supplied with lupin feeding, responsible for initiating increases in testicular growth and ovulation rate. Increases in both of these parameters were closely related to the supply of additional energy but not protein. The production of acetate and glucose resulting from supplementary feeding with 750 g lupins/d was measured using infusions of "1"4C tracers. Subsequently, infusions of glucose and acetate (individually and in combination) were found to produce similar increases in ovulation rate to those measured in ewes receiving lupins. It was concluded that effects of nutrition on ...

Energy Technology Data Exchange (ETDEWEB)

Smoke management in buildings during fire events often uses mechanical ventilation systems to maintain smoke layer elevation above a safe evacuation path. Design of these systems requires accurate correlations for the smoke production rate of the buoyant fire plume. One design issue is the smoke production rate of fire plumes which spill out from a fire compartment, under a balcony and up through an atrium or other large volume. Current engineering correlations for these balcony spill plumes are based on a combination of one-tenth scale test data and theoretical analysis. Questions have arisen over the suitability of these correlations for real-scale designs. A combined program of full-scale experimentation and CFD modeling is being conducted to analyze the accuracy of these correlations. A full-scale experimental facility was constructed with a 5 m by 5 m by 15 m fire compartment connected to a four-story atrium. Propane fires in the compartment produce balcony ...

Energy Technology Data Exchange (ETDEWEB)

One approach to validate nuclear power plant (NPP) signals makes use of pattern recognition techniques. This approach often assumes that there is a set of signal prototypes that are continuously compared with the actual sensor signals. These signal prototypes are often computed based on empirical models with little or no knowledge about physical processes. A common problem of all data-based models is their limited ability to make predictions on the basis of available training data. Another problem is related to suboptimal training algorithms. Both of these potential shortcomings with conventional approaches to signal validation and sensor operability validation are successfully resolved by adopting a recently proposed learning paradigm called the support vector machine (SVM). The work presented here is a novel application of SVM for data-based modeling of system state variables in an NPP, integrated ...

DEFF Research Database (Denmark)

The sources of non-white noise in Blood Oxygenation Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) are many. Familiar sources include low-frequency drift due to hardware imperfections, oscillatory noise due to respiration and cardiac pulsation and residual movement artefacts not accounted for by rigid body registration. These contributions give rise to temporal autocorrelation in the residuals of the fMRI signal and invalidate the statistical analysis as the errors are no longer independent. The low-frequency drift is often removed by high-pass filtering, and other effects are typically modelled as an autoregressive (AR) process. In this paper, we propose an alternative approach: Nuisance Variable Regression (NVR). By inclusion of confounding effects in a general linear model (GLM), we first confirm that the spatial distribution of the various fMRI noise sources is similar to what has already been ...

Energy Technology Data Exchange (ETDEWEB)

To significantly improve the simulation of climate by general circulation models (GCMs), systematic errors in representations of relevant processes must first be identified, and then reduced. This endeavor demands that the GCM parameterizations of unresolved processes, in particular, should be tested over a wide range of time scales, not just in climate simulations. Thus, a numerical weather prediction (NWP) methodology for evaluating model parameterizations and gaining insights into their behavior may prove useful, provided that suitable adaptations are made for implementation in climate GCMs. This method entails the generation of short-range weather forecasts by a realistically initialized climate GCM, and the application of six-hourly NWP analyses and observations of parameterized variables to evaluate these forecasts. The behavior of the parameterizations in such a weather-forecasting framework can provide insights on ...

Science.gov (United States)

The social work literature is replete with studies evaluating social workers' direct practice interventions, but strikingly few have assessed how well social workers are faring in the political arena. This study tests a major theoretical model, the civic voluntarism model, developed to explain why some citizens become involved in politics, whereas others do not. The study sample consisted of 396 randomly selected social workers licensed in 11 states, all of whom completed a 25-minute telephone survey. Social workers were surveyed to determine the role of the following variables in explaining social workers' political activity levels--resources needed to participate, psychological engagement, and attachment to recruitment networks. The results indicate that the civic voluntarism model was significant and accounted for 42 percent of the variance. The strongest predictors of social workers' political ...

International Nuclear Information System (INIS)

We revisit our original papers on the burst mode of accretion by incorporating a detailed energy balance equation into a thin-disk model for the formation and evolution of circumstellar disks around low-mass protostars. Our model includes the effect of radiative cooling, viscous and shock heating, and heating due to stellar and background irradiation. Following the collapse from the prestellar phase allows us to model the early embedded phase of disk formation and evolution. During this time, the disk is susceptible to fragmentation, depending upon the properties of the initial prestellar core. Globally, we find that higher initial core angular momentum and mass content favors more fragmentation, but higher levels of background radiation can moderate the tendency to fragment. A higher rate of mass infall onto the disk than that onto the star is a necessary but not a sufficient condition for disk fragmentation. More locally, ...

International Nuclear Information System (INIS)

We present a proof-of-concept analysis of the measurement of the health damage of ozone (O_3) produced from nitrogen oxides (NO_x=NO+NO_2) emitted by individual large point sources in the eastern United States. We use a regional atmospheric model of the eastern United States, the Comprehensive Air quality Model with Extensions (CAMx), to quantify the variable impact that a fixed quantity of NO_x emitted from individual sources can have on the downwind concentration of surface O_3, depending on temperature and local biogenic hydrocarbon emissions. We also examine the dependence of resulting O_3-related health damages on the size of the exposed population. The investigation is relevant to the increasingly widely used 'cap and trade' approach to NO_x regulation, which presumes that shifts of emission over time and space, holding the total fixed over the course of the summer O_3 season, will have minimal effect on the ...

Energy Technology Data Exchange (ETDEWEB)

MAGMA is a FORTRAN computer code designed to viscous flow in in situ vitrification melt pools. It models three-dimensional, incompressible, viscous flow and heat transfer. The momentum equation is coupled to the temperature field through the buoyancy force terms arising from the Boussinesq approximation. All fluid properties, except density, are assumed variable. Density is assumed constant except in the buoyancy force terms in the momentum equation. A simple melting model based on the enthalpy method allows the study of the melt front progression and latent heat effects. An indirect addressing scheme used in the numerical solution of the momentum equation voids unnecessary calculations in cells devoid of liquid. Two-dimensional calculations can be performed using either rectangular or cylindrical coordinates, while three-dimensional calculations use rectangular coordinates. All derivatives are approximated by finite ...

International Nuclear Information System (INIS)

The effects of the heating rate from 0.6 up to 50"oC.s"-"1 on the thermoluminescence of #alpha#-Al_2O_3:C are very intensive. The material rapidly loses its high sensitivity as the heating rate increases. The peak shape characteristics, peak maximum and full width at half maximum agree only qualitatively with those theoretically predicted. The trapping parameters calculated by the curve fitting method, the peak shape method, the variable heating rate method and the initial rise method, were found to decrease as the heating rate increases. The validity of the results are discussed in the framework of the kinetic models. (author).

British Library Electronic Table of Contents (United Kingdom)

Motivation: It is commonplace for authors to propose a new classification rule, either the operator construction part or feature selection, and demonstrate its performance on real data sets, which often come from high-dimensional studies, such as from gene-expression microarrays, with small samples. Owing to the variability in feature selection and error estimation, individual reported performances are highly imprecise. Hence, if only the best test results are reported, then these will be biased relative to the overall performance of the proposed procedure. Results: This article characterizes reporting bias with several statistics and computes these statistics in a large simulation study using both modeled and real data. The results appear as curves giving the different reporting biases as...

British Library Electronic Table of Contents (United Kingdom)

This study aimed to explore the impact of perceived service quality and self-concept on consumer attitude and purchase process using channel type (physical and Internet) as a segmentation variable. From the perspective of consumer behaviour, this study attempted to estimate a relational model and perform an empirical validation using female cosmetics and skincare products as an example. It was discovered that the influence of perceived service quality and self-concept on consumer attitude, purchase intention and behaviour, satisfaction, and loyalty varied with channel type. The analysis result revealed that physical stores presented higher levels of agreement with all research perspectives than Internet stores. However, only two relational paths have a higher influencing effect in physical...

Energy Technology Data Exchange (ETDEWEB)

The original objective of our EMSP research was to design, develop, and test new in situ field permeameters for use in spatial variability studies of unsaturated hydraulic properties. We initially focused on activities related to development and testing of techniques for inverting permeameter data, development of numerical tools for data inversion, error evaluation for permeameter design, and permeameter component design. However, the results of error evaluations for permeameter design caused us to redirect our research, and reformulate our research objectives. We discovered that small, simple measurement errors lead to significant bias in the estimated hydraulic properties and their spatial statistics. Our reformulated research objective became the evaluation of the origin, impact and relevance of spatial bias in field-and laboratory-estimated unsaturate hydraulic properties, with an emphasis on spatial statistics and the resulting predictions of stochastic ...

Energy Technology Data Exchange (ETDEWEB)

Differential cross sections for dijet photoproduction in association with a leading neutron using the reaction e{sup +}+p{yields}e{sup +}+n+jet+jet+X{sub r} have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb{sup -1}. The fraction of dijet events with a leading neutron in the final state was studied as a function of the jet kinematic variables. The cross sections were measured for jet transverse energies E{sub T}{sup jet}>6 GeV, neutron energy E{sub n}>400 GeV, and neutron production angle {theta}{sub n}<0.8 mrad. The data are broadly consistent with factorization of the lepton and hadron vertices and with a simple one-pion-exchange model.

CERN Document Server

In this paper we develop an analytical framework for the study of electrochemical impedance of mixed ionic and electronic conductors (MIEC). The framework is based on first-principles and it features the coupling of electrochemical reactions, surface transport and bulk transport processes. We utilize this work to analyze two dimensional systems relevant for fuel cell science via finite element method (FEM). Alternate current Impedance Spectroscopy (IS) of a ceria symmetric cell is simulated near equilibrium condition (zero bias) for a wide array of working conditions including variations of temperature and $H_2$ partial pressure on a two dimensional fuel cell sample with patterned metal electrodes. The model shows agreement of IS curves with the experimental literature with the relative error on the impedance being consistently below 2%. Important two-dimensional effects such the effects of thickness decrease and the influence of variable ...

British Library Electronic Table of Contents (United Kingdom)

Women who have academic careers in engineering have successfully navigated the social identity threats that prevent many other women from feeling that they belong in science, technology, engineering, and math fields. In this research, we examined what factors may be related to resilience in these academic environments. Female academics in engineering and nonengineering fields watched a fictitious conference video depicting either an unbalanced ratio of men to women or a balanced ratio. Subjective measures of identity threat were collected. Past experience with discrimination, positive experience with female role models, family support, and general social support were associated with a greater sense of belonging to or desire to participate in the conference. These variables all buffered neg...

British Library Electronic Table of Contents (United Kingdom)

An Environmental Impact Assessment (EIA) study for any project is a time- consuming process because it has a large number of dependent and independent variables that must be taken into account. Although EIAs are dependent on geo-spatial information in order to make an assessment, there are no standard rules for conducting an environmental assessment. In addition, each assessment objective is case-dependent, based on what information is available. This paper presents a new framework for the analysis phase of the Environmental Impact Assessment (EIA) for projects, based on the integration between remote sensing technology, geographic information systems, and spatial modeling. The framework comprehensively analyzes the environmental vulnerability around the project areas and its impact on the...

Energy Technology Data Exchange (ETDEWEB)

When the transmission line is very long or the generator is operated at a power factor nearly equal to 1.0, the machine regulated by an automatic voltage regulator (AVR) cannot be operated stably due to poor dynamic stability. To overcome this difficulty, the so called power system stabilizer (PSS) is very useful, in that output power or rotor speed of the generator is used as a feedback signal. The primary obective of the PSS is to damp the swing of the generator as quickly as possible. A method is proposed for designing PSS which yields a given eigenvalue. In the second method, the use of a Heffron-Phillips model is discussed. Next, a detailed procedure for the proposed design method is presented. A generalized method of a PSS design based on Park's equation and matrix operation is proposed.

British Library Electronic Table of Contents (United Kingdom)

Both cultural inheritance and cultural diversification of diets may play an important role in animal evolution. Here we studied how diet innovation and cultural change relate to cultural inheritance in a changing environment. We did this by studying diet cultures in group foragers adapting to environmental change through learning, and the consequences this has for diet differentiation between groups. We used an individual-based model of `monkeys' that learn what to eat in a rich environment, and we changed resource species that are available in the environment. Relative to social influences on learning that arise spontaneously in groups, we found that more direct social learning, in the sense of observing another individual and copying what it eats, helps groups deal with high levels of en...

CERN Document Server

Based on recent work on simplicial diffeomorphisms in colored group field theories, we develop a representation of the colored Boulatov model, in which the GFT fields depend on variables associated to vertices of the associated simplicial complex, as opposed to edges. On top of simplifying the action of diffeomorphisms, the main advantage of this representation is that the GFT Feynman graphs have a different stranded structure, which allows a direct identification of subgraphs associated to bubbles, and their evaluation is simplified drastically. As a first important application of this formulation, we derive new scaling bounds for the regularized amplitudes, organized in terms of the genera of the bubbles, and show how the pseudo-manifolds configurations appearing in the perturbative expansion are suppressed as compared to manifolds. Moreover, these bounds are proved to be optimal.

Energy Technology Data Exchange (ETDEWEB)

An adaptive power system stabilizer (APSS) employing a new self-optimizing pole shifting control strategy and its application to a power system are described in this paper. Based on an identified model of the system, the control is computed by an algorithm which shifts the closed-loop poles of the system to some optimal locations inside the unit circle in the z-domain to minimize a given performance criterion. With the self-optimization property, outside intervention in the controller design procedure is minimized, thus simplifying the tuning procedure during commissioning. Also, a new method of calculating the variable forgetting factor in real-time parameter identification is discussed. Studies show that the proposed APSS can provide good damping of the power system over a wide operating range and significantly improve the dynamic performance of the system.

International Nuclear Information System (INIS)

This study is concerned to the perforation phenomena of the oblique dual-plate by projectile. Experiment and simulation related to that was carried out. the variables considered in this phenomena include the electrolytic zinc coated steel sheet and carbon steel rod. In the former, the confirmation and projectile velocity possible phenomena of real phenomena is done, the latter, the effect of parameter such as time-step and grid space length is analyzed by using the three-dimensional Lagrangian explicit time-integration finite element code, HEMP. This code use the eight node hexahedral elements and in this study, Von-Mises Criteria is used as the strength model, Mie-Gruneisen is as the Equation of State. The simulation was performed by contrast with the experiment. Through the calibration of the parameter of Lagrangian code, reasonable result was approached.

Energy Technology Data Exchange (ETDEWEB)

The aim of the thesis is to validate concepts used in hydrocarbon generation and migration models; the model considered is the Temispack model developed by IFP, and the validation is based on the investigation of the thermal and hydraulic evolution in various sedimentary basins. It is shown that, in general, the thermal history of sediments is influenced by external processes (sedimentation rates, lithology, climate changes, regional-scale groundwater circulations) which frequently overprint internal processes (variations of crustal/mantle heat flow). It is found that external processes can frequently explain past thermal events that were erroneously attributed to internal causes (tectonic-thermal events). The origin of over-pressures in young basins with high sedimentation rates is shown to be generally related to compaction disequilibrium. Shale permeability values calibrated against overpressure profiles are consistent ...

Science.gov (United States)

... 1111/j.1558-5646.2007.00203.x THE BALDWIN EFFECT AND GENETIC ASSIMILATION: REVISITING TWO MECHANISMS OF ... to phenotypic plast...

UK PubMed Central (United Kingdom)

Cellular actions of thyroid hormone may be initiated within the cell nucleus, at the plasma membrane, in cytoplasm, and at the mitochondrion. Thyroid hormone nuclear receptors (TRs) mediate the biological...Full Text Available

UK PubMed Central (United Kingdom)

Activating AMPK or inactivating calcineurin slows ageing in Caenorhabditis elegans^1,2...Full Text Available

UK PubMed Central (United Kingdom)

Temperature is an important modulator of longevity and aging in both poikilotherms and homeotherm animals. In homeotherms, temperature homeostasis is regulated primarily in the preoptic area...Full Text Available

UK PubMed Central (United Kingdom)

Carbohydrate-directed endocytosis is mediated by a receptor, the hepatic binding protein; it is responsible for the clearance of galactose-terminated glycoproteins from the circulation. This process...Full Text Available

UK PubMed Central (United Kingdom)

Chemoreceptors are crucial components in the bacterial sensory systems that mediate chemotaxis. Chemotactic responses exhibit exquisite sensitivity, extensive dynamic range and precise adaptation....Full Text Available

CERN Document Server

Web Services and mobile data services are the newest trends in information systems engineering in wired and wireless domains, respectively. Web Services have a broad range of service distributions while mobile phones have large and expanding user base. To address the confluence of Web Services and pervasive mobile devices and communication environments, a basic mobile Web Service provider was developed for smart phones. The performance of this Mobile Host was also analyzed in detail. Further analysis of the Mobile Host to provide proper QoS and to check Mobile Host's feasibility in the P2P networks, identified the necessity of a mediation framework. The paper describes the research conducted with the Mobile Host, identifies the tasks of the mediation framework and then discusses the feasible realization details of such a mobile Web Services mediation framework.

DEFF Research Database (Denmark)

Udgivelsesdato: May 2009

KoreaScience (Korea)

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KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

After the introduction Chapter 2 presents details of the ecological-economic analysis based on the FAO/IIASA agro-ecological zones (AEZ) approach for evaluation of biophysical limitations and agricultural production potentials, and IIASA's Basic Linked System (BLS) for analyzing the world's food economy and trade system. The BLS is a global general equilibrium model system for analyzing agricultural policies and food system prospects in an international setting. BLS views national agricultural systems as embedded in national economies, which interact with each other through trade at the international level. The combination of AEZ and BLS provides an integrated ecological-economic framework for the assessment of the impact of climate change. We consider climate scenarios based on experiments with four General Circulation Models (GCM), and we assess the four basic socioeconomic development pathways and emission scenarios as ...

Energy Technology Data Exchange (ETDEWEB)

As part of studies into the siting of a deep repository for nuclear waste, Swedish Nuclear Fuel and Waste Management Company (SKB) has commissioned the Alternative Models Project (AMP). The AMP is a comparison of three alternative modeling approaches for geosphere performance assessment for a single hypothetical site. The hypothetical site, arbitrarily named Aberg is based on parameters from the Aespoe Hard Rock Laboratory in southern Sweden. The Aberg model domain, boundary conditions and canister locations are defined as a common reference case to facilitate comparisons between approaches. This report presents the results of a discrete fracture pathways analysis of the Aberg site, within the context of the SR 97 performance assessment exercise. The Aberg discrete fracture network (DFN) site model is based on consensus Aberg parameters related to the Aespoe HRL site. Discrete fracture pathways are ...

Energy Technology Data Exchange (ETDEWEB)

Improvements to a small diesel engine turbocharger were made based on data gathered during a previous Army contract. The improved turbocharger was fabricated and tested on a small, four cylinder, 239 CID diesel engine. Engine dynamometer test data revealed a 2 to 9 percent reduction in fuel consumption at all points over the operating envelope. A turbocharger was operated for 1011 hours at speeds between 70000 and 78000 rpm without incident. The ball bearings were in excellent condition at the end of the test. A math model of the engine and turbocharger was generated. The model was used to estimate 13 Mode Federal Diesel Emissions Cycle, the LA4 driving cycle and the application of the variable area turbine nozzle (VATN) turbocharger to a diesel engine driven generator set. A recommendation was made to build a gen set demo unit. A fuel savings of 8 to 10 percent was estimated for a 30KW DED generator set.

Energy Technology Data Exchange (ETDEWEB)

The study was performed for evaluating the risk effect of digital systems on the total plant. Based on risk monitor, a fault tree model for the Korean Standard Nuclear Power Plants (KSNPP), we integrate the fault-tree models for Digital Plant Protection System (DPPS) and Digital Engineered SaFety Actuation System (DESFAS) which are the most important safety-critical I and C systems in the KSNPP. In this study, however, three important factors (the probabilities of manual actuation failure, the software failure probability, and the watchdog timer fault coverage) are treated as the variables of the sensitivity study because quantification methodologies for these factors are not developed yet. Not only the unavailability of digital safety-critical system itself, but also the risk effect of digital systems on the total plant should be assessed to prove the safety of digital systems. The result of sensitivity study shows that ...

Energy Technology Data Exchange (ETDEWEB)

A spectral element method embodying Large Eddy Simulation based on Re- Normalization Group theory for simulating Sub Grid Scale viscosity was chosen for this work. This method is embodied in a computer code called NEKTON. NEKTON solves the unsteady, 2D or 3D,incompressible Navier Stokes equations by a spectral element method. The code was later extended to include the variable density and multiple reactive species effects at low Mach numbers, and to compute transport of large particles governed by inertia. Transport of small particles is computed by treating them as trace species. Code computations were performed for a number of test conditions typical of flow past a deep tube bank in a boiler. Results indicate qualitatively correct behavior. Predictions of deposition rates and deposit shape evolution also show correct qualitative behavior. These simulations are the first attempts to compute flow field results at realistic flow Reynolds numbers of the order of ...

Energy Technology Data Exchange (ETDEWEB)

Moving out of the scientific community research laboratories, computational fluid dynamics (CFD) software packages are now allowing industrials to analyse and optimize industrial processes involving the use of gases, liquids and even some two-phase fluids. Their attractiveness and their impact stems out from the opportunity they offer to bring insight into an existing unit, or even at the design stage, by displaying the spatial distribution of process relevant variables such as temperature, concentration. The filling of the spacing in between a two-layer window is a simple example. This new opportunity of visualisation is at times an unique way, when the process environment is an opaque one, such as liquid metal flowing into a tundish or when measurements of flows may be a long and tedious work, such as flows within water treatment basins. This environment we are to investigate in order to optimize can also be a harsh one, due to its high temperature level for ...

Energy Technology Data Exchange (ETDEWEB)

A multivariate adaptive power system stabilizer is proposed. The advantages of using coordinated governor and excitation control are discussed, and the problems associated with constant parameter power system stabilizers (CPSS) are highlighted. The proposed multi-input multi-output (MIMO) power system stabilizer can coordinate the governor and excitation control and can overcome the problems associated with CPSS in power system stabilization. Selective multivariable state modelling, identification and control methods are investigated and the MIMO least squares technique with variable forgetting factor is used for system identification, guaranteeing good parameter tracking after a disturbance. Two multivariable self-tuning algorithms are investigated, the generalized minimum variance control and pole-shifting control algorithms. The multivariable self-searching pole-shifting algorithm is developed. Models of a single machine ...

Energy Technology Data Exchange (ETDEWEB)

Faulting the feedwater for a 19-tube, model steam generator with 10 ppM of caustic once a week produced widespread shallow 25 to 75 micrometers (1 to 3 mils) intergranular attack (IGA) on alloy 600 tubes and an axial tube rupture at the steam-water interface after 4.8 years. An extensive investigation of the IGA damage found little correlation with major test variables beyond the indication that mill-annealed tubing was more susceptible to attack than stress-relieved tubing. The most likely cause of the tube rupture was caustic that concentrated to high levels in a porous scale on the tube at the liquid-vapor interface where there was a high available superheat. Nondestructive examination (NDE) eddy current probes underestimated the depth of IGA and were not sensitive to circumferential cracks less than 152 micrometers (6 mils) deep that were above and below the roll transition zones of tubes in the tubesheet.