Energy Technology Data Exchange (ETDEWEB)

To address the need for integrated models of advanced power generation systems and for improved analysis techniques, the US Department of Energy (DOE), through the Morgantown Energy Technology Center (METC), has supported the development of performance, emissions, and cost models of several advanced power generation systems, including integrated gasification combined cycle (IGCC), externally-fired combined cycle (EFCC) and pressurized fluidized bed combustion (PFBC) concepts. Simultaneously, numerical methods for simulation of uncertainties and optimization of process flowsheets have been implemented in the DOE`s public version of ASPEN. The new process models and computational capabilities have been applied to demonstrate the benefits of quantitative approaches to dealing with uncertainty and for optimizing technologies in the face of uncertainty. This paper focuses on modeling and assessment of the ...

Energy Technology Data Exchange (ETDEWEB)

The IGCC of the U.S. government was created under the intent of Public Law 93-410 (1974) to serve as a forum for the discussion of Federal plans, activities, and policies that are related to or impact on geothermal energy. Eight Federal Departments were represented on the IGCC at the time of this meeting. The main presentations in this report were on: Department of Energy Geothermal R&D Program, the Ormat binary power plant at East Mesa, CA, Potential for direct use of geothermal at Defense bases in U.S. and overseas, Department of Defense Geothermal Program at China Lake, and Status of the U.S. Geothermal Industry. The IGCC briefing books and minutes provide a historical snapshot of what development and impact issues were important at various time. (DJE 2005)

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

In connection with the ERP project 'Dynamic modelling of staged gasification processes' a gasification simulator has been constructed. The simulator consists of: a mathematical model of the gasification process developed at Technical University of Denmark, a user interface programme, IGSS, and a communication interface between the two programmes. (BA)

Science.gov (United States)

... Descriptors : *Terminal flight facilities, *Traffic ... Ground support, Queueing theory, Passengers ... Delay, Assessment, Stochastic processes, Ground ...

Science.gov (United States)

... AIR TRAFFIC, TERMINAL FLIGHT ... FLIGHT, RANDOM VARIABLES, STOCHASTIC PROCESSES ... COMPUTER PROGRAMS, QUEUEING THEORY. ...

UK PubMed Central (United Kingdom)

We examined the effect of spatial iconicity (a perceptual simulation of canonical locations of objects) and word-order frequency on language processing and episodic memory of orientation. Participants...Full Text Available

International Nuclear Information System (INIS)

This report describes accomplishment of simulations of Pyrochemical Process Operation by using virtual engineering models. The pyrochemical process using molten salt electrorefining would introduce new technologies for new fuels of particle oxide, particle nitride and metallic fuels. This system is a batch treatment system of reprocessing and re-fabrication, which transports products of solid form from a process to next process. As a results, this system needs automated transport system for process operations by robotics. In this study, a simulation code system has been prepared, which provides virtual engineering environment to evaluate the pyrochemical process operation of a batch treatment system using handling robots. And the simulation study has been conducted to evaluate the required system ...

International Nuclear Information System (INIS)

The author describes the purpose, classification and main process of acceptance test of full scope simulator of Daya Bay Nuclear Power Plant, including the correction of non-conformance items which are discovered during the performance of acceptance tests. The results of the acceptance tests show that the model accepted by the full scope simulator of Daya Bay Nuclear Power Plant is fully able to cope with the simulation of normal transients and incidental transients and the performance of the simulator indeed compiled with the technical specifications which are defined n the relevant contracts.

International Nuclear Information System (INIS)

Energy deposition process by relativistic fast electrons produced by ultra-intense laser pulses is discussed. The process is calculated with a two dimensional Fokker-Planck simulation code including binary and collective collisions coupled with electromagnetic field. We focused on Velocity Distribution Function (VDF) dependence in the simulation. The results show that the spread angle of the fast electrons distribution affects energy deposition area and deposited energy is concentrated in the vicinity of the propagation axis of the fast electrons. It may be also suggested that self-pinch effect of a fast electron beam causes large deposition energy. (author)

British Library Electronic Table of Contents (United Kingdom)

The results obtained from experimental investigations and mathematical simulation of horizontal steam generators are considered. Recommendations for continuing these works are given.

Energy Technology Data Exchange (ETDEWEB)

The mainly instationary operation of a solar heated receiver can be simulated with sufficient accuracy only if data about the dynamic behavior are available. For this reason, the dynamic behavior of a solar cavity receiver with parabolic dish collector is investigated. The development of a mathematical simulation considering heat transfer and storage processes is presented and the procedure for a numerical solution is illustrated. The performance of the calculation method is finally demonstrated by simulating the passage of a cloud.

Energy Technology Data Exchange (ETDEWEB)

For IGCC, the primary investment is too high due to the demand of high gasification efficiency. For PFBCC, the thermal efficiency is too low due to the relatively low turbine inlet temperature and the hot working medium of the gas turbine is not easy to clean. A new scheme is proposed for coal fired combined cycle to overcome the main drawbacks of IGCC and PFBCC. The research targets are developing a new cycle construction of coal fired combined cycle to raise the efficiency and reduce the primary investment. Actually, the new scheme is a synthesis of some existing proposals. It adopts partial gasification to reduce the primary investment of the gasification equipment. The un-gasified surplus solid is then fed to a pressurized fluidized bed boiler, but adopting Curtiss Wright type external combustion to lower the ash content in the working medium. The gas fuel from the partial gasifier is combusted in a top combustor to further increase the ...

Energy Technology Data Exchange (ETDEWEB)

In this paper the simulation of hybrid processes containing membrane units will be discussed. For this purpose a user-defined module for simulation and design of membrane processes was implemented into the simulation program AspenPlus. The advantages can be summarized as follows: - any combination of membrane processes with all other units already implemented in AspenPlus is possible, including internal recycle streams, - utilization of the physical property models and data bases of AspenPlus is possible, - cost and sensitivity analysis can be performed. These benefits are demonstrated in detail for a membrane vapor recovery unit for the treatment of tank farm off-gas, for a two-stage reverse osmosis plant for organic/-organic separations and for a combination of distillation and pervaporation for the separation of a dimethylcarbonate/methanol mixture. (orig.)

Energy Technology Data Exchange (ETDEWEB)

Given that fossil fuel fired power plants are among the largest and most concentrated producers of CO{sub 2} emissions, recovery and sequestration of CO{sub 2} from the flue gas of such plants has been identified as one of the primary means for reducing anthropogenic CO{sub 2} emissions. In this study, ALSTOM Power Inc. (ALSTOM) has investigated several coal fired power plant configurations designed to capture CO{sub 2} from effluent gas streams for use or sequestration. Burning fossil fuels in mixtures of oxygen and recirculated flue gas (made principally of CO{sub 2}) essentially eliminates the presence of atmospheric nitrogen in the flue gas. The resulting flue gas is comprised primarily of CO{sub 2}. Oxygen firing in utility scale Pulverized Coal (PC) fired boilers has been shown to be a more economical method for CO{sub 2} capture than amine scrubbing (Bozzuto, et al., 2001). Additionally, oxygen firing in Circulating Fluid Bed Boilers (CFB's) can be more economical than ...

Energy Technology Data Exchange (ETDEWEB)

Due to size and costs of big slewing rings, the common methods of experimental trial and error together with destructive test methods for verification of the inductive hardening process are limited. Thereby it is essential to simulate the hardening process in addition to the tests. With these simulations, it should be possible to get conclusions for the hardening pattern, the residual stress and distortion. With actually existing methods a fully three dimensional simulation is extremely time consuming. For that reason, a new method was developed that combines two dimensional with three dimensional simulation to shorten the time for calculation tremendously. (orig.)

Energy Technology Data Exchange (ETDEWEB)

The traditional process for developing large-scale simulations is cumbersome, time consuming, costly, and in some cases, inadequate. The topics of software components and component-based software engineering are being explored by software professionals in academic and industrial settings. A component is a well-delineated, relatively independent, and replaceable part of a software system that performs a specific function. Many researchers have addressed the potential to derive a component-based approach to simulations in general, and a few have focused on military simulations in particular. In a component-based approach, functional or logical blocks of the simulation entities are represented as coherent collections of components satisfying explicitly defined interface requirements. A simulation is a top-level aggregate comprised of a collection of components that ...

Energy Technology Data Exchange (ETDEWEB)

The overall goal of this work is to design and optimize a biodiesel production process from soybean oil. To achieve this goal, several inter-connected activities were undertaken. First, an initial flowsheet for the process was synthesized. The performance of this flowsheet along with the key design and operating criteria were identified by conducting computer-aided simulation using ASPEN Plus. Various scenarios were simulated to provide sufficient understanding and insights and to select a base-case flowsheet. Next, mass and energy integration studies were performed to reduce the consumption of material and energy utilities, improve environmental impact, and enhance profitability. Capital cost estimation was carried out using the ICARUS Process Evaluator computer-aided tool linked to the results of the ASPEN Plus simulation. The operating cost of the ...

Energy Technology Data Exchange (ETDEWEB)

The Monte Carlo simulation method is applied to calculate the nucleon transfer part of the imaginary optical-model potential in colliding heavy ions. In the process of transfer of nucleons from one nucleus to the other, forward and backward neutrons and protons are treated separately by taking into consideration the effect of the Coulomb forces and the potential energy surfaces (driving forces). The Pauli exclusion principle is also incorporated properly in the calculation.

Energy Technology Data Exchange (ETDEWEB)

This work deals with a time-resolved optical study of the avalanche and streamer formation phases leading to breakdown in atmospheric nitrogen. The authors present the results obtained for nitrogen, from experiments and two-dimensional model simulations. This model is used to obtain a better insight in the relevant mechanisms and processes by a comparison of measurements and simulation data. The trends of externally measured quantities correspond with those predicted by the model.

Science.gov (United States)

The report describes a computer model developed by TVA to simulate the performance and determine the economics of coal cleaning, or coal cleaning combined with flue gas desulfurization (FGD), for power plant emission control processes over a wide range of user-specified condition...

British Library Electronic Table of Contents (United Kingdom)

Due to the low thermal conductivity of ceramics large temperature gradients are present through the powder particles during plasma spray deposition. As a result the particles often impinge at the substrate in a semi-molten form; which in turn substantially affects the final characteristics of the coating being formed. This study is dedicated to the novel modelling development and simulation of a semi-molten droplet impingement. The study examines the impingement process during impact, spreading and solidification of semi-molten zirconia. The simulation provides an insight to the heat transfer process during impact and solidification of a semi-molten powder particle and illustrates the freezing-induced break-up mechanism at the splat periphery.

Energy Technology Data Exchange (ETDEWEB)

This work is the first active crossflow filter testing of the new strontium-permanganate process for Envelope C at the Savannah River Technology Center. Extreme filtration difficulties with the ferric hydroxide precipitation led to investigations of other chemistries with simulants. The current process includes the isotopic dilution by precipitation from inactive strontium nitrate addition. A permanganate strike to replace ferric reagents was found to provide practical filterability and good lanthanide or transuranic decontamination. That work had been supported with simulant and active beaker testing.

International Nuclear Information System (INIS)

In the construction work for the Unit No.5 Turbine Building at Hamaoka Nuclear Power Station, the collaboration work for the planning and the coordination of the building construction and the machinery installation was carried out utilizing three-dimensional computer aided design (3D CAD) information. It was the first time in Japan for a building constructor and a plant manufacturer to work together, exchanging 3D CAD data of the whole building and adjusting the construction schedule. It was made possible to confirm the correspondence concerning the planning of both companies from the primary stage of the project by the total process simulation and to adjust on-going work precisely by the partial process simulation.

Energy Technology Data Exchange (ETDEWEB)

To apply the CO{sub 2} absorber at about 1000{sup o}C for integrated coal gasification combined cycle (IGCC) furnace, the reactions of calcium oxide and CO{sub 2} at high temperatures was examined. Calcium carbonate reacts with sodium hydrogen carbonate below 200{sup o}C and forms sodium-calcium complex carbonate. The sodium-calcium complex carbonate melts at 813{sup o}C, and the carbon dioxide absorption and discharge reversible reactions of calcium-oxide takes place via liquid at around 1000{sup o}C. Sintering of calcium oxide at high temperature has been successfully avoided by the addition of sodium.

Energy Technology Data Exchange (ETDEWEB)

A stochastic wind simulation for VAWTs (VSTOC) has been developed which yields turbulent wind-velocity fluctuations for rotationally sampled points. This allows three-component wind-velocity fluctuations to be simulated at specified nodal points on the wind-turbine rotor. A first-order convection scheme is used which accounts for the decrease in streamwise velocity as the flow passes through the wind-turbine rotor. The VSTOC simulation is independent of the particular analytical technique used to predict the aerodynamic and performance characteristics of the turbine. The VSTOC subroutine may be used simply as a subroutine in a particular VAWT prediction code or it may be used as a subroutine in an independent processor. The independent processor is used to interact with a version of the VAWT prediction code which is segmented into deterministic and stochastic modules. Using VSTOC in this fashion is very efficient with ...

International Nuclear Information System (INIS)

We present results of multiple-time-scale simulations of 5, 10 and 15 keV low temperature ion implantation of arsenic on silicon (100), followed by high temperature anneals. The simulations start with a molecular dynamics (MD) calculation of the primary state of damage after 10ps. The results are then coupled to a kinetic Monte Carlo (MC) simulation of bulk defect diffusion and clustering. Dose accumulation is achieved considering that at low temperatures the damage produced in the lattice is stable. After the desired dose is accumulated, the system is annealed at 800 degrees C for several seconds. The results provide information on the evolution for the damage microstructure over macroscopic length and time scales and affords direct comparison to experimental results. We discuss the database of inputs to the MC model and how it affects the diffusion process.

DEFF Research Database (Denmark)

This paper presents the concept of a biological inspired reconfigurable hardware cell architecture which supports self-organisation and self-healing. Two fundamental processes in biology, namely fertilization-to-birth and cell self-healing have inspired the development of this cell architecture. In biology as well as in our hardware cell architecture it is the DNA which enables these processes. We propose a platform based on the electronic DNA (eDNA) and show through simulation, its capabilities as a new generation of robust reconfigurable hardware platforms. We have created a Java based simulator to simulate our self-organisation and self-healing algorithms and the results obtained from this looks promising.

British Library Electronic Table of Contents (United Kingdom)

The importance of temperature in the determination of the yield of an annual crop (groundnut; Arachis hypogaea L. in India) was assessed. Simulations from a regional climate model (PRECIS) were used with a crop model (GLAM) to examine crop growth under simulated current (1961-1990) and future (2071-2100) climates. Two processes were examined: the response of crop duration to mean temperature and the response of seed-set to extremes of temperature. The relative importance of, and interaction between, these two processes was examined for a number of genotypic characteristics, which were represented by using different values of crop model parameters derived from experiments.The impact of mean and extreme temperatures varied geographically, and depended upon the simulated genotypic properties....

Energy Technology Data Exchange (ETDEWEB)

This guide describes the simulator`s governing equations, constitutive functions and numerical solution algorithms of the STOMP (Subsurface Transport Over Multiple Phases) simulator, a scientific tool for analyzing multiple phase subsurface flow and transport. The STOMP simulator`s fundamental purpose is to produce numerical predictions of thermal and hydrologic flow and transport phenomena in variably saturated subsurface environments, which are contaminated with volatile or nonvolatile organic compounds. Auxiliary applications include numerical predictions of solute transport processes including radioactive chain decay processes. In writing these guides for the STOMP simulator, the authors have assumed that the reader comprehends concepts and theories associated with multiple-phase hydrology, heat transfer, thermodynamics, radioactive chain decay, and ...

Science.gov (United States)

It is well known that one of the main advantages of the high speed forming (HSF) processes is the improvement in the forming limits of the used materials.Using the Electromagnetic Forming (EMF) technology two materials have been tested with different mechanical and physical properties: the AA5754 aluminium and the AZ31B magnesium alloys.The EMF process principle can be described as follows: A significant amount of electrical energy is stored in a bank of capacitors which are suddenly discharged releasing all the stored energy. This electric discharge runs through a coil which generates an intense transient magnetic field. At the same time transient Eddy currents are induced in the electrically conductive part placed some millimetres far from the coil. Another intense magnetic field is generated due to those Eddy currents but on the opposite direction as the one generated by the coil. A big magnetic repulsion force is created between the part ...

International Nuclear Information System (INIS)

Ion implantation and subsequent annealing are essential stages in today's advanced CMOS processing. Although the dopant implanted profile can be accurately predicted by analytical fits calibrated with SIMS profiles, the damage has to be estimated with a binary collision approximation implant simulator. Some models have been proposed, like the '+n', in an attempt to simplify the anneal simulation. We have used the atomistic kinetic Monte Carlo dados to elucidate which are the implant modeling features most relevant in the simulation of transient enhanced diffusion (TED). For the experimental conditions studied we find that the spatial correlation of the I, V Frenkel pairs is not critical in order to yield the correct I supersaturation, that can be simulated just taking into account the net I-V excess distribution. In contrast to, simulate impurity ...

Energy Technology Data Exchange (ETDEWEB)

P.S. Lowell and Co., Inc. (Lowell and Co.) and Jay S. Dweck, Consultant, Inc. (JSD) under contract to the US Department of Energy (DOE) Morgantown Energy Technology Center (METC) have developed and implemented an aqueous electrolyte calculation capability into the ASPEN (Advanced System for Process Engineering) process simulator. This report documents the efforts of Task 1 which were to implement the basic calculational capability. Task 2 involves development of several unit operations models and demonstration of the models in simulating environmental control processes in coal gasification and shale oil processing plants. Task 1 of the project involved several subtasks: selection of a chemical equilibrium algorithm; selection of activity coefficient algorithms; selection of species for inclusion in the initial implementation; collection of required data for the ...

Science.gov (United States)

This was written as the research final report of (sup D)evelopment of Auto- tuning System for the Process Optimal Control of Wolsung NPP(sup ()95ZS13). In this research, a new PID controller auto-tuning algorithm and Auto-tuning System which can simulate ...

Energy Technology Data Exchange (ETDEWEB)

This paper presents a mathematical model for simultaneous heat and moisture transfer under freezing-thawing in porous hygroscopic material. Even below O{sup o}C, unfrozen liquid water exists in the material which plays an important role in the processes. The model takes into account the existence of unfrozen liquid water. The system is treated as a three-(gas, liquid and solid) phase system of water. Moisture chemical potential is used as a moisture potential. Under freezing, moisture chemical potential is a unique function of local temperature. So, during freezing, two unknown variables to be solved are solid water content and moisture potential or temperature. A simple example of simulation for freezing processes is shown. (author)

International Nuclear Information System (INIS)

Depending on their unique physical properties, proton and heavy ions have taken an irreplaceable role in modern means of tumor treatment. One-step process and two-step process physical models were employed to explain the mechanism of ion energy loss. The transport process of proton and "1"2C in water was simulated by Geant4 toolkit to study the physical properties of ion beam. The calculation results were discussed, which showed the advantages and disadvantages of proton and "1"2C in the medical application. (authors)

Energy Technology Data Exchange (ETDEWEB)

The topic of supervised learning within the conceptual framework of artificial neural network (ANN) models is addressed. An ANN is a parallel distributed processing system that consists of many computationally simple processing elements interconnected through uni-directional weighted connections. Such networks, which are roughly patterned after biological nervous systems, have been proposed for use in areas in which the traditional von Neumann computer architecture has been relatively unsuccessful. Learning in these networks is accomplished through the use of algorithms that adjust the values of the connection weights. The work presented here addresses the issue of improving the rate at which ANNs can learn to achieve the mapping of an input pattern to a desired output pattern. The most successful learning algorithms for accomplishing this task are based on gradient descent error minimization techniques. However, the large amount of training ...

Energy Technology Data Exchange (ETDEWEB)

Current advanced CMOS source/drain engineering involves the use of amorphizing implants with 3D geometry. Upon annealing, the induced transient enhanced diffusion (TED) can only be accurately predicted if the amorphized region is correctly modeled, as well as the formation and evolution of extended defects, particularly 3 1 1's and dislocation loops. In addition to the extended defects, already modeled in the atomistic kinetic Monte-Carlo simulator DADOS, we have developed a physically based modeling approach for the implant-induced damage build-up, amorphization and recrystallization, suitable to handle device-size process simulation. It is based on amorphous pockets (3D, irregular shape agglomerates of an arbitrary number of interstitials and vacancies, plus trapped impurities) with a size-dependent activation energy for recombination. The model is able to reproduce experimental aspects like the crystal-amorphous ...

Science.gov (United States)

We develop a 3-D model to simulate the synthetic aperture radar (SAR) image formation process of an undulated vegetation canopy such as corn grown in fields with large periodic drainage reliefs. We explain how the simulated SAR image of undulated vegetation medium is obtained by the convolution of a 2-D slice of the 3-D simulated SAR system point spread function [(PSF), emulating the SAR beam modeled by a cosine modulated Gaussian], with the 2-D projection of the observed undulated vegetation canopy (modeled with scatterers randomly distributed in 3-D undulated space) followed by the extraction of each look envelope, the summation of looks, and sampling in azimuthal and range directions. Our model is useful to study the parameters involved in the formation and the analysis of SAR images of undulated vegetation medium. Validation of simulations made with actual SAR images shows that ...

Energy Technology Data Exchange (ETDEWEB)

The Stockpile Stewardship Program (SSP) is a single, highly integrated technical program for maintaining the safety and reliability of the U.S. nuclear stockpile. The SSP uses past nuclear test data along with future non-nuclear test data, computational modeling and simulation, and experimental facilities to advance understanding of nuclear weapons. It includes stockpile surveillance, experimental research, development and engineering programs, and an appropriately scaled production capability to support stockpile requirements. This integrated national program will require the continued use of current facilities and programs along with new experimental facilities and computational enhancements to support these programs. The Advanced Simulation and Computing program (ASC) is a cornerstone of the SSP, providing simulation capabilities and computational resources to support the annual stockpile assessment and certification, to ...

International Nuclear Information System (INIS)

This paper presents the results of a model for the impact of potential contamination produced by radionuclide leaking due to long-term physical, chemical and hydrogeological processes occurring in a LILW repository and in the natural environment. The analysis contains a deterministic and also a probabilistic approach for uncertainty assessment. The input function, i.e., the source term was evaluated by using AMBER code and the entire analysis was accomplished by using GOLDSIM, a powerful tool to support probabilistic simulation in management and decision-making in engineering and science. The results obtained were compared to previous simulations and uncertainty analyses (FEHM). (authors)

Energy Technology Data Exchange (ETDEWEB)

The performance of a solar chemical heat pipe was studied using CO{sub 2}reforming of methane as the endothermic reaction. A directly heated vertical reactor, packed with a rhodium catalyst was used. The solar tests were carried out in the Schaeffer solar furnace of the Weizmann Institute of Science. The power absorbed was up to 6.3 KW, the maximal flow rates of the gases reached 11,000 1/h, and the methane conversions reached 85%. A computer model was developed to simulate the process. Agreement of the calculations with the experimental results was quite satisfactory.

CERN Document Server

An effective computer program for three dimensional relativistic hydrodynamical model has been developed. It implements a new approach to the early hot phase of relativistic heavy-ion collisions. The computer program simulates time-space evolution of nuclear matter in terms of ideal-fluid dynamics. Equations of motions of hydrodynamics are solved making use of finite difference methods. Commonly-used algorithms of numerical relativistic hydrodynamics RHLLE and MUSTA-FORCE have been applied in simulations. To speed-up calculations, parallel processing has been made available for solving hydrodynamical equations. The test results of simulations for 3D, 2D and Bjorken expansion are reported in this paper. As a next step we plan to implement the hadronization algorithm by implementing the continuous particle emission for freeze-out and comparing it with Cooper-Frye formula.

Science.gov (United States)

The understanding of transport processes that occur in naturally fractured geothermal systems is far from being complete. Often, evaluation and numerical simulations of fractured geothermal reservoirs, are carried out by assuming equivalent porous media and homogeneous petrophysical properties within big matrix blocks. The purpose of this paper, is to present a comparison between results obtained from numerical studies of a naturally fractured reservoir treated as a simple porous medium and the simulation of some real aspects of the fractured reservoir. A general conclusion outlines the great practical importance of considering even approximately, the true nature of such systems. Our results show that the homogeneous simplified evaluation of the energy resource in a fractured system, could result in unrealistic estimates of the reservoir capacity to generate electricity.

Energy Technology Data Exchange (ETDEWEB)

The effect of sodium gluconate anion (SG) on the corrosion and scale inhibition of ordinary steel in simulated cooling water has been studied using weight loss, polarisation curves, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) techniques. SG was studied in concentration from 10{sup -4} M to 10{sup -1} M. Results obtained reveal that SG perform excellently as corrosion and scaling inhibitor for ordinary steel in simulated cooling water. An increase of SG concentration leads to the increase of the corrosion potential towards the positive direction. The inhibition efficiency was a low temperature dependence. The inhibitor mechanism was treated as an adsorption process according to Langmuir adsorption isotherm. The SEM/EDAX data show that was a corrosion and scale inhibitor.

CERN Document Server

Numerical results on the translocation of long biopolymers through mid-sized and wide pores are presented. The simulations are based on a novel methodology which couples molecular motion to a mesoscopic fluid solvent. Thousands of events of long polymers (up to 8000 monomers) are monitored as they pass through nanopores. Comparison between the different pore sizes shows that wide pores can host a larger number of multiple biopolymer segments, as compared to smaller pores. The simulations provide clear evidence of folding quantization in the translocation process as the biopolymers undertake multi-folded configurations, characterized by a well-defined integer number of folds. Accordingly, the translocation time is no longer represented by a single-exponent power law dependence on the length, as it is the case for single-file translocation through narrow pores. The folding quantization increases with the biopolymer length, ...

British Library Electronic Table of Contents (United Kingdom)

This research aims to develop a simulation approach based on system dynamics modelling (SDM) and adaptive network based fuzzy inference system (ANFIS) for quantifying and reducing the bullwhip effect in a multi-product, multi-stage supply chain. The proposed model is comprised of three groups of variables influencing the bullwhip effect, namely the structure of a supply chain network, supply chain contributions (ordering process in regular situation or when a supplier has a promotion or shortage gaming) and supply chain performances (the number of defects and ordering lead time). As a result, a two layer simulation model is developed with three generic models. The flexibility of this proposed approach is its ability to model various types of ordering policies which are basic inventory poli...

British Library Electronic Table of Contents (United Kingdom)

A new numerical technique called the convolution-based particle tracking (CBPT) method is developed to simulate resident or flux-averaged solute concentrations in groundwater models. The method is valid for steady-state flow and linear transport processes such as sorption with a linear sorption isotherm and first-order decay. The CBPT method uses particle tracking to take advantage of the ability of particle-based approaches to maintain sharp fronts for advection-dominated transport problems common in groundwater modeling and because of the flexibility of the random walk method to simulate a wide range of possible forms of the dispersion tensor. Furthermore, the algorithm for carrying out the convolution and superposition calculation from particle tracking results is very efficient. We sho...

Energy Technology Data Exchange (ETDEWEB)

Plans for the disposal of radioactive liquid and solid wastes presently stored in double-shell tanks at the Hanford Site call for retrieval and processing of the waste to create forms suitable for permanent disposal. Waste will be retrieved from a tank using a submerged slurry pump in conjunction with one or more rotating slurry jet mixer pumps. Pacific Northwest Laboratory (PNL) has conducted tests using simulated waste slurries to assess the effects of a impinging slurry jet on the corrosion rate of the tank wall and floor, an action that could potentially compromise the tank`s structural integrity. Corrosion processes were investigated on a laboratory scale with a simulated neutralized cladding removal waste (NCRW) slurry and in a subsequent test with simulated neutralized current acid waste (NCAW) slurry. The test slurries simulated the actual NCRW and NCAW ...

Energy Technology Data Exchange (ETDEWEB)

A laboratory differential simulation method is used for the design of carbonization columns at coal-tar processing in which phenols are regenerated from phenolate solution by carbon dioxide absorption. The design method is based on integration of local absorption rates of carbon dioxide along the column. The local absorption rates into industrial phenolate mixture are measured in a laboratory model contactor for various compositions of the gas and liquid phases under the conditions that ensure the absorption rates in the laboratory absorber simulate the local rates in the industrial column. On the bases of the calculations, two-step carbonization columns were designed for 30000 t/year of the phenolate solution treatment by carbon dioxide. The absorption proceeds at higher pressure of 500 kPa and temperatures from 50 to 65 C, pure carbon dioxide is used and toluene is added. These conditions have the following favourable ...

Energy Technology Data Exchange (ETDEWEB)

As silicon-integrated circuit technology enters the sub-100 nm realm, continued progress will depend on a fundamental understanding of the physics of materials processing. The high cost of processing experimental lots and the speed at which new devices must be brought to the market have created a new emphasis on realistic physical models incorporated in technology CAD (TCAD) simulation tools. The volume bring together materials scientists, TCAD researchers and silicon technologists to review recent developments in the integrated-circuit community and to identify key issues for future research in this field. Results of research on the physical mechanisms involved in silicon device processing is presented both from experimental and theoretical viewpoints. The application of this fundamental research to TCAD process simulation models is also addressed. Topics ...

Energy Technology Data Exchange (ETDEWEB)

The Stockpile Stewardship Program (SSP) is a single, highly integrated technical program for maintaining the safety and reliability of the U.S. nuclear stockpile. The SSP uses past nuclear test data along with current and future nonnuclear test data, computational modeling and simulation, and experimental facilities to advance understanding of nuclear weapons. It includes stockpile surveillance, experimental research, development and engineering programs, and an appropriately scaled production capability to support stockpile requirements. This integrated national program requires the continued use of current facilities and programs along with new experimental facilities and computational enhancements to support these programs. The Advanced Simulation and Computing Program (ASC)1 is a cornerstone of the SSP, providing simulation capabilities and computational resources to support the annual stockpile assessment and ...

British Library Electronic Table of Contents (United Kingdom)

Variability in production is one of the largest factors that negatively impacts construction project performance. A common construction practice to protect production systems from variability is the use of buffers (Bf). Construction practitioners and researchers have proposed buffering approaches for different production situations, but these approaches have faced practical limitations in their application. A multiobjective analytic model (MAM) is proposed to develop a graphical solution for the design of Work-In-Process (WIP) Bf in order to overcome these practical limitations to Bf application, being demonstrated through the scheduling of repetitive building projects. Multiobjective analytic modeling is based on Simulation?Optimization (SO) modeling and Pareto Fronts concepts. Simulation...

Energy Technology Data Exchange (ETDEWEB)

Since actinide mononitride has several superior thermal and neutronic properties, nitride fuel is considered as a candidate for future nuclear systems, such as advanced fast reactors and accelerator-driven system. Establishing reprocessing technology is one of key technologies for the development of nitride fuel cycle. In addition to general advantages of pyrochemical process, such as the potential for economy, radiation and proliferation resistance, recycling of N-15 in nitride fuel seems to be practical in comparison with conventional hydro-process. Following the electrochemical measurements of nitride fuel in LiCl-KCl molten salt, the experimental study on closing nitride fuel cycle has been carried out in JAEA by used of TRU nitride and burnup simulated nitride samples. Recent progress of the study is summarized in this paper.

CERN Document Server

This contribution deals with identification of fractional-order dynamical systems. System identification, which refers to estimation of process parameters, is a necessity in control theory. Real processes are usually of fractional order as opposed to the ideal integral order models. A simple and elegant scheme of estimating the parameters for such a fractional order process is proposed. This method employs fractional calculus theory to find equations relating the parameters that are to be estimated, and then estimates the process parameters after solving the simultaneous equations. The said simultaneous equations are generated and updated using particle swarm optimization (PSO) technique, the fitness function being the sum of squared deviations from the actual set of observations. The data used for the calculations are intentionally corrupted to simulate real-life conditions. ...

Energy Technology Data Exchange (ETDEWEB)

Hyogo-ken Nanbu earthquake with a focus in the Akashi straits has given huge earthquake damages in and around Awaji Island and Kobe City in 1995. It is clear that the basement structure, which is steeply deepened at Kobe City from Rokko Mountains towards the coast, and the focus under this related closely to the local generation of strong ground motion. Generation process of the strong ground motion was discussed using 2D and 3D numerical simulation methods. The 3D pseudospectral method was used for the calculation. Space of 51.2km{times}25.6km{times}25.6km was selected for the calculation. This space was discretized with the lattice interval of 200m. Consequently, it was found that the basement structure with a steeply deepened basement, soft and weak geological structure thickly deposited on the basement, and earthquake faults running under the boundary of base rock and sediments related greatly to the generation of strong ground motion. ...

Energy Technology Data Exchange (ETDEWEB)

An experiment was conducted on the structure of mesoscopic calculating method for cement-based composite materials. The purpose was utilization for the simulation of mesoscale failure processes and the development of new composite materials. Mesh split based on Voronoi polygons was applied as the discrete limit analysis of the cement-based composite materials containing aggregate particles taking the arrangement of random particles into consideration, and a two-dimensional rigid-body/spring model was employed as the model. The nonhomogeneity of concrete was represented by three kinds of different spring parameters which were aggregate, mortar matrix and their interfaces. The simulation results were summarized as follows: The stress-strain curve went into a non-linear state from the 30% of the maximum stress. The generation of interfacial crack started on the side of the aggregate, but the propagation of the crack was ...

Energy Technology Data Exchange (ETDEWEB)

A new atomistic approach to Si device process simulation is presented. It is based on a Monte Carlo diffusion code coupled to a binary collision program. Besides diffusion, the simulation includes recombination of vacancies and interstitials, clustering and re-emission from the clusters, and trapping of interstitials. We discuss the simulation of a typical room-temperature implant at 40 keV, 5{times}10{sup 13} cm{sup {minus}2} Si into (001)Si, followed by a high temperature (815{degree}C) anneal. The damage evolves into an excess of interstitials in the form of extended defects and with a total number close to the implanted dose. This result explains the success of the {open_quote}{open_quote}+1{close_quote}{close_quote} model, used to simulate transient diffusion of dopants after ion implantation. It is also in agreement with recent transmission electron microscopy observations of ...

Energy Technology Data Exchange (ETDEWEB)

The present paper is concerned with development and application of a so-called Effective Convection Model (ECM), which aims to provide a detailed, mechanistic description of heat transfer processes in a BWR lower plenum. The ECM is a Computational Fluid Dynamics (CFD)-like tool which employs a simpler and more effective approach to compute heat transfer by solving only energy conservation equation instead of solving the full set of Navier-Stokes and energy equations by a CFD code. We implement the ECM in a CFD code (Fluent), with detailed description of the ECM development, implementation and validation. A dual approach is used to validate the ECM, namely validation against experimental data and against heat transfer results obtained by CFD predictions in the same geometries and conditions. Insights gained from CFD simulations are also used to improve ECM. The ECM capability as an effective tool to simulate heat transfer of ...

Energy Technology Data Exchange (ETDEWEB)

The goal of this DOE Vision-21 project work scope is to develop an integrated suite of software tools that can be used to simulate and visualize advanced plant concepts. Existing process simulation software does not meet the DOE's objective of ''virtual simulation'' which is needed to evaluate complex cycles. The overall intent of the DOE is to improve predictive tools for cycle analysis, and to improve the component models that are used in turn to simulate the cycle. Advanced component models are available; however, a generic coupling capability that will link the advanced component models to the cycle simulation software remains to be developed. In the current project, the coupling of the cycle analysis and cycle component simulation software will be based on an existing suite of programs. The ...

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.

International Nuclear Information System (INIS)

A process has been developed that exploits the characteristics of microwave heating for the vitrification of high-level radioactive liquid waste. This process, microwave vitrification, has been successfully operated at pilot plant scale in an active cell using simulated liquid waste containing several curies of radioactivity. Excellent decontamination factors have been achieved for both volatiles and nonvolatiles with an average ruthenium decontamination factor of 490 and a gross alpha emitter decontamination factor of 100,000. Almost all the radioactivity is incorporated in a glass block.

Energy Technology Data Exchange (ETDEWEB)

The purpose of this research is to develop a technically and economically feasible process for biologically producing H(sub 2) from synthesis gas while, at the same time, removing harmful sulfur gas compounds. Six major tasks are being studied: 1. Culture development, where the best cultures are selected and conditions optimized for simultaneous hydrogen production and sulfur gas removal; 2. Mass transfer and kinetic studies in which equations necessary for process design are developed; 3. Bioreactor design studies, where the cultures chosen in Task 1 are utilized in continuous reaction vessels to demonstrate process feasibility and define operating conditions; 4. Evaluation of biological synthetic gas conversion under limiting conditions in preparation for industrial demonstration studies; 5. Process scale-up where laboratory data are scaled to larger-size units in preparation for ...

Energy Technology Data Exchange (ETDEWEB)

An overview is provided of an evolving atomistic and kinetic model of semiconductor growth that unifies the main features of strain relaxation in low and high lattice misfit heteroepitaxy. The model reveals a kinetic pathway for dislocation formation during growth with little or no energy cost at low misfits, thus providing a way out of the longstanding dilemma of too high dislocation nucleation energies predicted by classical theories of the equilibrium behavior of a fixed number of particles at low misfits. The essential kinetic process underlying the model are identified on the basis of comparison of the predictions of kinetic Monte-Carlo simulations of growth with real-time or in-situ data obtained in such experiments as reflection high-energy electron diffraction (RHEED) and scanning probe microscopy (SPM). Relative significance of these atomistic kinetic processes is shown to naturally lead to strain relaxation via ...

Energy Technology Data Exchange (ETDEWEB)

This paper examined the potential of steam assisted gravity drainage (SAGD) technology for increasing productivity in the Orinoco heavy oilfields of Venezuela. A computerized simulation tool was used to generate a matrix of parameters needed to compare SAGD processes with cold production techniques in the Carabobo region of the Orinoco belt. Parameters included vertical connectivity, oil saturation, and net pay. Monte Carlo simulations and uncertainty assessments were used to generate cold production scenarios. Optimized SAGD scenarios were then designed for each case. Results of the study suggested that vertical local connectivity was an important parameter for the identification of suitable areas for EOR and SAGD. Unfavorable conditions for the application of SAGD during early production stages were identified. SAGD behaviour improved through the adjustment of injection rates during different stages of the ...

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 ...

Energy Technology Data Exchange (ETDEWEB)

The applicability of the electro-slag melting method for treating plutonium contaminated metallic waste was studied. A 100kg test furnace was built and simulated metallic waste was melted and solidified in this furnace. Waste volume was reduced to 1/25 with a decontamination factor of 25 and the slag and the copper mold are repeatedly usable. The process is expected to be employed in the project of PWTF (Plutonium contaminated Waste Treatment Facilities).

Energy Technology Data Exchange (ETDEWEB)

Classical molecular dynamics simulations are carried out to investigate the salvation shell exchange kinetics of potassium ion in bulk water, chloroform, and carbon tetrachloride. The reactive flux method is used to compute the dissociation rates. The influence of the solvent on the reaction rates and kinetic properties of this exchange process will be discussed. Comparison will be also be made to the prediction of the Grote-Hynes theory.

Energy Technology Data Exchange (ETDEWEB)

The results of a time-resolved study of the avalanche and streamer formation phases leading to breakdown in atmospheric nitrogen and dry air. Results of experiments and two-dimensional simulations are presented. It is shown what processes are responsible for the formation of a streamer. The trends of externally measured quantities correspond with those predicted by our model. 3 figs., 5 refs.

Energy Technology Data Exchange (ETDEWEB)

The catalytic liquefaction of a Chinese bituminous coal was simulated by artificial neural network. Three liquefaction variables, catalyst loading, reaction temperature and reaction time were used as inputs and tetrohydrofuran (THF) conversion and toluene (T) conversion were used as outputs. The artificial neural network, trained by the experimental data, could represent the liquefaction process, with a mean squared deviation of less than 0.025. 7 refs.,1 fig., 3 tabs.

Energy Technology Data Exchange (ETDEWEB)

The presented paper describes the formulation of the fractional mass balances which are used to calculate the concentration and size distribution of char in the balance cells of a circulating fluidized bed boiler. In case of using the shrinking core model additionally the distribution of conversion of the char particles is calculated. Basically two reaction models (a shrinking particle and a shrinking core model) are available to describe the combustion process. The model considers all essential physico/chemical phenomena (primary fragmentation, attrition, mass transfer to gas phase) which have to be taken into account for the description of the combustion process. The model is part of an overall simulation program for circulating fluidized bed boilers. This engineering simulator has been developed to return the main performance parameters of such systems like temperature along the furnace height, size ...

Energy Technology Data Exchange (ETDEWEB)

The climate modeling community has focused recently on improving our understanding of certain processes, such as cloud feedbacks and ocean circulation, that are deemed critical to climate-change prediction. Although attention to such processes is warranted, emphasis on these areas has diminished a general appreciation of the role played by the large-scale dynamics of the extratropical atmosphere. Lack of interest in extratropical dynamics may reflect the assumption that these dynamical processes are a non-problem as far as climate modeling is concerned, since general circulation models (GCMs) calculate motions on this scale from first principles. Nevertheless, serious shortcomings in our ability to understand and simulate large-scale dynamics exist. Partly due to a paucity of standard GCM diagnostic calculations of large-scale motions and their transports of heat, momentum, potential vorticity, and ...

International Nuclear Information System (INIS)

Macroparticle acceleration driven by low current, high voltage cathode spots has been investigated for potential applications ranging from micrometeoroid simulation to nanoparticle deposition/implantation. Acceleration by this process was observed to occur when nanometer and micrometer-sized particles were exposed to a high voltage pulse in the presence of a plasma discharge. The applied negative voltage pulse initiates the formation of multiple, high voltage, low current cathode spots which provide the mechanism of actual acceleration of the charged dust particles. Dust streams generated by this process were detected using laser scattering techniques. Cathode spot behavior was also documented. The particle impact craters observed at the surface of downstream witness badges were documented using scanning electron microscopy and light microscopy. The observed impacts suggest the presence of energetic macroparticles formed ...

Energy Technology Data Exchange (ETDEWEB)

The general objective of the presented work is process intensification by means of reduced furnace chamber volumes in combination with the use of low-NOx burner technologies. Fundamental experimental investigations of the reaction zone of different burner types were made. For the development of new burner designs the CFD code FLUENT was used. Throughout the investigations it was possible to increase the furnace heating density from 62 kW/m3 up to 1133 kW/m3. To demonstrate possible technical applications two simulated industrial furnaces designs have been investigated. One main conclusion the work gave is that process intensification without an increase of pollutant emissions is possible by optimizing furnace and burner design and also position and geometry of the furnace load in a combined strategy. (author)

CERN Document Server

Two-dimensional simulations of the coarsening process of the isotropic/smectic-A phase transition are presented using a high-order Landau-de Gennes type free energy model. Defect annihilation laws for smectic disclinations, elementary dislocations, and total dislocation content are determined. The computed evolution of the orientational correlation length and disclination density is found to be in agreement with previous experimental observations showing that disclination interactions dominate the coarsening process. The mechanism of smectic disclination movement, limited by the absorption and emission of elementary dislocations, is found to be facilitated by curvature walls connecting interacting disclinations. At intermediate times in the coarsening process, split-core dislocation formation and interactions displaying an effective disclination quadrupole configuration are observed. This work provides ...

Energy Technology Data Exchange (ETDEWEB)

Porosity evolution at reactive interfaces is a key process that governs the evolution and performances of many engineered systems that have important applications in earth and environmental sciences. This is the case, for example, at the interface between cement structures and clays in deep geological nuclear waste disposals. Although in a different transport regime, similar questions arise for permeable reactive barriers used for biogeochemical remediation in surface environments. The COMEDIE project aims at investigating the coupling between transport, hydrodynamics and chemistry when significant variations of porosity occur. The present work focuses on a numerical benchmark used as a design exercise for the future COMEDIE-2D experiment. The use of reactive transport simulation tools like Hytec and Crunch provides predictions of the physico-chemical evolutions that are expected during the future experiments in laboratory. Focus is given in ...

Energy Technology Data Exchange (ETDEWEB)

The objective of the current MITRE study is to estimate the cost of the coal derived liquid products that result from processing low rank coals in the Wilsonville and HRI CTSL configurations. The resultant cost of liquids is then compared to liquids produced from bituminous coals. The methodology used to accomplish the above objective was to utilize the MITRE coal liquefaction cost model to assess the overall technical and economic performance of low rank coals in both the Wilsonville and HRI configurations. Actual test data from Wilsonville and HRI was used as the basis for these analyses. This test data is modified to simulate complete resid recycle extinction and to standardize the operating performance of the deashing unit. This corrected yield data is then used in the simulation models to predict the overall performance and economics of a conceptual commercial coal liquefaction facility. 9 refs., 7 figs.

International Nuclear Information System (INIS)

In this work, the pulse plasma nitriding process of pure iron is modelled using a kinetic model derived from the Fick's laws. This approach based on the error function model allows to simulate the growth kinetics of a biphase configuration consisting of #gamma#'-Fe_4N_1_-_x and #epsilon#-Fe_2_-_3N iron nitrides under specified conditions. By coupling the kinetics data about the diffusivities of nitrogen in #alpha#-Fe, #gamma#' and #epsilon# phases to the thermodynamic description of the Fe-N phase diagram, it is possible to evaluate the kinetic constant at each growing phase interface, the thickness of nitrided layer, and predict the nitrogen concentration profiles. The comparison between the experimental and theoretical results shows the reliability of the simulation results.

Energy Technology Data Exchange (ETDEWEB)

The performance of bunch-feedback systems based on two-tap FIR filters is discussed, particularly for transverse cases. Since they are the simplest type of FIR digital filters, the two-tap FIR filters should be suited to systems that require a very fast processing speed. However, in these feedback systems, a bunch must turn along a ring several times from the position-measurement to feedback kicking. Within these turns, irregular phase-jumps in the betatron motion can occur, due to several causes, such as the wake forces and beam-beam force. The discussion given in this paper is focussed on the effect of beam-beam collisions on these feedback systems. Based on linear theory and simulation studies, it has been found that these feedback systems can work with good performance, even under the influence of a strong beam-beam force. (author)

Science.gov (United States)

Recently the author showed that the widely used simulation code TDA3D, even though a single frequency code, can be used to determine the power spectrum in the SASE process with excellent approximation in the exponential growth regime. In this paper, the author applies this method to the BNL Cornell Wiggler A SASE experiment as an example. When the gain is not very high, there are many modes in the radiation, which seems to make the analytical calculation very difficult. However, he shows that the increment of the radiation due to SASE over the spontaneous radiation can be expanded in terms of guided modes with rapid convergence. Thus when the spontaneous radiation is substracted from the SASE power during the calculation, there is a good agreement between the analytical theory and the numerical simulation.

International Nuclear Information System (INIS)

This report presents a view of and commentary on the current status of equipment qualification (EQ) in nuclear industries of the major western nations. The introductory chapters discuss the concepts of EQ, the elements of EQ process and highlight some of the key issues in EQ. A brief review of industry practices and some of the prevalent industrial standards is presented, followed by an overview of current regulatory positions in the USA, France, Germany and Sweden. A summary and commentary on the latest research findings on issues relating to accident simulation, to aging simulation and some special topics related to EQ, has been contributed by Franklin Research Centre of Philadelphia. The last part of the report deals with equipment qualification in Canada and gives recommendations on EQ for new plants as well as currently operational CANDU nuclear power plants.

Science.gov (United States)

In this paper we study theoretically a pulsed corona discharge plasma in air at atmospheric pressure. A self consistent one-dimensional model, using a flux-corrected transport numerical scheme, is presented to achieve it. The charged particle kinetics in this model are described by one-dimensional continuity equations coupled with Poisson's equations. The spatio-temporal local field, charge density variations and the velocity profile of an ionizing front are calculated to describe the dynamical behavior of corona discharge plasmas. The simulation results of a wire-in-cylinder corona discharge plasma explain the physical mechanisms of discharge processes. These results may also be apply to obtain the optimizing parameters for designing the plasma reactor.

British Library Electronic Table of Contents (United Kingdom)

This paper aims to provide a comprehensive review of the various models or simulations for predicting drug release from bulk-degrading systems. A brief description of bulk degradation processes and factors affecting the degradation rate, and consequently the release kinetics, is presented first. Next, several important classical models, often used as the basis for subsequent model development, are discussed. Both mathematical models and Monte-Carlo based simulations have been developed for controlled release from bulk-degrading systems. The mathematical models can be further subdivided into two categories. First, the diffusion-based models whose transport mechanism is mainly governed by diffusion, but with degradation-dependent diffusion coefficients. These are generally simpler and easier...

International Nuclear Information System (INIS)

The aim of this thesis is the design of a faults diagnosis-aiding system in a nuclear facility of the Cea. Actually the existing system allows the optimization of the production processes in regular operating conditions. Meanwhile during accidental events, the alarms, managed by threshold, are bringing no relevant information. To increase the reliability and the safety, the human operator needs a faults diagnosis-aiding system. The developed system, SECAPI, combines problem solving techniques and automatic learning techniques, that allow the diagnosis and the the simulation of various faults happening on nuclear facilities. Its reasoning principle uses case-based and rules-based techniques. SECAPI owns a learning module which reads out knowledge connected with faults. It can then simulate various faults, using the inductive logical computing. SECAPI has been applied on a radioactive tritium treatment operating channel, at ...

Science.gov (United States)

This paper details the design of a premixed, swirl-stabilized combustor that was designed and built for the express purpose of obtaining validation-quality data for the development of large eddy simulations (LES) of gas turbine combustors. The combustor features nonambiguous boundary conditions, a geometrically simple design that retains the essential fluid dynamics and thermochemical processes that occur in actual gas turbine combustors, and unrestrictive access for laser and optical diagnostic measurements. After discussing the design detail, a preliminary investigation of the performance and operating envelope of the combustor is presented. With the combustor operating on premixed methane/air, both the equivalence ratio and the inlet velocity were systematically varied and the flame structure was recorded via digital photography. Interesting lean flame blowout and resonance characteristics were observed. In addition, the combustor exhibited ...

Energy Technology Data Exchange (ETDEWEB)

In calibration measurements with low energy X-rays, a double peak effect appears in low pressure proportional counters with a helix, when used for simulation of tissue equivalent diameters considerably larger than 2 m. An interpretation of this phenomenon is discussed, based upon electron capture and electric field perturbation at the counter helix. A description of the physical processes is presented showing that the double peak effect is a problem in the case of helix counters (called also Rossi counters) for all simulated diameters. Conclusions are drawn on systematic errors introduced by the counter helix into microdosimetric spectra and anti y/sub D/ of photons and neutrons. The authors recommend to use cylindrical counters with optimized geometrical and electronic parameters rather than the spherical counters with a helix discussed.

British Library Electronic Table of Contents (United Kingdom)

A study of the ordinary mild steel/cooling water interface, with and without inhibitor, was carried out using electrochemical impedance spectroscopy (EIS). EIS spectra in uninhibited medium reveal that a layer of corrosion and scale products is formed naturally and evolves with the immersion time. Monosaccharides derivatives were used as corrosion inhibitors. Most of them exhibit good behaviour against corrosion of ordinary steel in simulated water systems. Their inhibiting efficiency increases with concentration rise and depends on molecular structure especially -OH groups' position on two adjacent carbons and their number. In addition, the effect of MoO4^2^- on the corrosion inhibition in the presence of the best inhibitor was also studied by EIS. The addition of MoO4^2^- enhanced the in...

International Nuclear Information System (INIS)

The benchmark calculations have been performed for MCNP-4B code using the measurement data of Wolsong nuclear power plant 2. In this study, the benchmark calculations have been performed for the criticality, boron worth, reactivity device worth, reactivity coefficient, and flux scan. Cross-section libraries were newly generated from ENDF/B-VI release 3 through NJOY97.114 data processing system and a three-dimensional full core model was developed for MCNP calculation. The simulation results have shown that the criticality is estimated within 4 mkn and the estimated reactivity worth of the control devices are generally consistent with the measurement data. In certain cases, the simulation results have shown large discrepancies against the measurement data, which will be sturdied further in the near future.

British Library Electronic Table of Contents (United Kingdom)

The availability of hourly air relative humidity (HARH) data is a key requirement for the estimation of epidemic dynamics of plant fungal pathogens, in particular for the simulation of both the germination of the spores and the infection process. Most of the existing epidemic forecasting models require these data as input directly or indirectly, in the latter case for the estimation of leaf wetness duration. In many cases, HARH must be generated because it is not available in historical series and when there is the need to simulate epidemics either on a wide scale or with different climate scenarios. Thirteen modelling solutions (MS) for the generation of this variable were evaluated, with different input requirements and alternative approaches, on a large dataset including several sites a...

Science.gov (United States)

Current theories on planetary formation establish that massive objects accrete gaseous envelopes, becoming gaseous planets if the accretion process proceeds before the accretion disc dissolution. One of the unsolved problems is that the planet formation is contextual to their quick migration towards the central star, due to the protoplanets-disc interaction, on a timescale lower by an order of magnitude than that of gas accretion onto the protoplanet. These arguments have been recently broached using N-body and/or Eulerian fluid-dynamics codes, mainly in 2D, or a mixing of them. In this work, 2D simulations with a SPH code are performed, to study the migration of one protoplanet. The goal is to scrutinise the protoplanet dragging as a function of planet's mass.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Nuclear Information System (INIS)

To demonstrate that the caustic-side solvent extraction (CSSX) process could remove cesium from Savannah River Site (SRS) high-level waste over long periods of time, an improved minicontactor (2-cm centrifugal contactor) was needed that could be operated for several days. In particular, the contractor temperature had to be controlled and contactor hydraulic performance needed to be improved. Because the process was to be continuous, provisions were made for a three-shift operation. With the improvements made and the operators trained, the CSSX process was run in a 33-stage minicontactor over a period of three days to remove cesium from an average SRS siumulant for the waste feed. The two key process goals were achieved: (1) the cesium was removed from the waste with decontamination factors greater than 40,000 and (2) the recovered cesium was concentrated by a factor of 15 in dilute nitric acid. These ...

Energy Technology Data Exchange (ETDEWEB)

A new air injection process called toe-to-heel air injection (THAI) has been developed to achieve very stable combustion performance in heavy oil wells by controlling gas override. In the THAI process, injected air migrates preferentially to the combustion front into a horizontal producer well by the oxygen diffusional gradient created under steady state conditions. This is possible because of the balance between the stoichiometric oxygen flux needed to burn the fuel (coke) laid down ahead of the combustion front and the removal of downstream combustion gases and mobilised fluids. This study involved a numerical simulation of the THAI process to increase the understanding of the processes involving fluid flow, heat transfer and chemical reactions taking place during in situ combustion. Two tests were conducted involving one dry and one wet combustion using heavy Wolf Lake Oil. The ...

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, ...

International Nuclear Information System (INIS)

Studies on the multivariate autoregressive (MAR) analysis are carried out for the choice of the parameters for modelling the data obtained from various sensors optimally. Accordingly, the roles of the parameters on the analysis results are identified and the related ambiguities are reduced. Experimental investigations are carried out by means of synthesized reactor noise-like data obtained from a digital simulator providing simulated stochastic signals of an operating nuclear reactor so that the simulator constitutes a favourable tool for the present studies aimed. As the system is well defined with its known structure, precise comparison of the MAR analysis results with the true values is performed. With the help of the information gained through the studies carried out, conditions to be taken care of for optimal signal processing in MAR modelling are determined. Although the parameters involved are ...

Energy Technology Data Exchange (ETDEWEB)

Glass produced during the Purex 4 campaigns of the Integrated DWPF Melter System (IDMS) and the 774 Research Melter contained a lower fraction of sludge components than targeted by the Product Composition Control System (PCCS). Purex 4 glass was more durable than the benchmark (EA) glass, but was less durable than most other simulated SRS high-level waste glasses. Further, the measured durability of Purex 4 glass was not as well correlated with the durability predicted from the DWPF process control algorithm, probably because the algorithm was developed to predict the durability of SRS high-level waste glasses with higher sludge content than Purex 4. A melter run, designated Purex 4 Remediation, was performed using the 774 Research Melter to determine if the initial PCCS target composition determined for Purex 4 would produce acceptable glass whose durability could be accurately modeled by the DWPF glass durability algorithm. Reagent grade ...

CERN Document Server

We investigate the formation and evolution of dwarf galaxies in a high resolution, hydrodynamical cosmological simulation of a Milky Way sized halo and its environment. Our simulation includes gas cooling, star formation, supernova feedback, metal enrichment and UV heating. In total, 90 satellites and more than 400 isolated dwarf galaxies are formed in the simulation, allowing a systematic study of the internal and environmental processes that determine their evolution. We find that 95% of satellite galaxies are gas-free at z=0, and identify three mechanisms for gas loss: supernova feedback, tidal stripping, and photo-evaporation due to re-ionization. Gas-rich satellite galaxies are only found with total masses above ~ 5x10^9 solar masses. In contrast, for isolated dwarf galaxies, a total mass of ~ 10^9 solar masses constitutes a sharp transition; less massive galaxies are predominantly gas-free at z=0, ...

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 simulation results of the ...

Energy Technology Data Exchange (ETDEWEB)

In the present dissertation, a hierarchical multiscale approach for modeling FePt nanoparticles by atomistic computer simulations is developed. By describing the interatomic interactions on different levels of sophistication, various time and length scales can be accessed. Methods range from static quantum-mechanic total-energy calculations of small periodic systems to simulations of whole particles over an extended time by using simple lattice Hamiltonians. By employing these methods, the energetic and thermodynamic stability of non-crystalline multiply twinned FePt nanoparticles is investigated. Subsequently, the thermodynamics of the order-disorder transition in FePt nanoparticles is analyzed, including the influence of particle size, composition and modified surface energies by different chemical surroundings. In order to identify processes that reduce or enhance the rate of transformation from the disordered to the ...

International Nuclear Information System (INIS)

A distinguishing design feature of CANDU nuclear reactors is the use of horizontal fuel channels housed in a horizontal vessel called a calandria, which is made of stainless steel 304L. Each channel consists of a Zr-2.5%Nb alloy pressure tube and an externally concentric Zr-2 calandria tube. The calandria tubes are joined to the end plates (tubesheets) of the calandria vessel by joints formed by roller expansion. The bores in the tubesheets are grooved. Roller expanded joints provide a cost effective means of joining dissimilar materials, require minimal space and no maintenance. The quality of these roller expanded joints is important from a sealing, strength and stress corrosion point of view. The roller expansion process consists of expanding the calandria tubes to deform them plastically against the bores and into the grooves of the tubesheets. Therefore, understanding the effect of the number, geometry and the pitch of the grooves on the quality of a roller ...

Energy Technology Data Exchange (ETDEWEB)

This report documents a one-dimensional numerical model, SAMFT1D, developed to simulate single-phase and multiphase fluid flow and solute transport in variably saturated porous media. The formulation of the governing equations and the numerical procedures used in the code for single-phase and multiphase flow and transport are presented. The code is constructed to handle single-phase as well as two or three-phase flow conditions using two integrated sets of computational modules. The fully implicit scheme is used in the code for both single-phase and multiphase flow simulations. Either the Crank-Nicholson scheme or the fully implicit scheme may be used in the transport simulation. The single-phase modules employ the Galerkin and upstream weighted residual finite element techniques to model flow and transport of water (aqueous phase) containing dissolved single-species contaminants concurrently or sequentially, and include ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

In this work, a comprehensive model including heat transfer, fluid flow and solidification was used to evaluate the performance of a novel delivery system for a single-belt steel casting process. This near-net-shape casting, although still in development, is one of the most promising routes for casting of low-carbon steel in large scale. This paper focuses on the performance of a low-Re {kappa}-{epsilon} model that was employed to simulate the three-dimensional turbulent flows fully-coupled with heat transfer and macroscopic solidification. Simulations were run for the intended conditions of caster operation, and the results obtained with the {kappa}-{epsilon} were compared with the results obtained with an ad hoc viscosity model, where the molecular viscosity was boosted 100 times, uniformly throughout the computational domain. A semi-analytical solution was employed for validating the models and the results showed that ...

International Nuclear Information System (INIS)

Very High Temperature gas cooled nuclear Reactor (VHTR), which was coupled with Sulfur-Iodine (SI) thermo-chemical cycle, has been selected for the Nuclear Hydrogen Development and Demonstration (NHDD) project in Korea Atomic Energy Research Institute. Among the various hydrogen production methods, Sulfur-Iodine (SI) thermo-chemical cycle is a good method as a massive hydrogen production without CO2 emission. In SI cycle, the sulfuric acid decomposition is one issue for the material corrosion on high temperature and pressure condition. For the simulation of the sulfuric acid decomposition, we designed a sulfuric acid loop with a small-scale gas loop which is simulated for the integrity and feasibility tests on a H2SO4 decomposition process. The primary objective of the loop is to validate the corrosion and the mechanical performances of a key component of the NHDD, Process Heat Exchanger (PHE). In this ...

International Nuclear Information System (INIS)

The underground storage tanks at the Hanford Complex contain mixed wastes generated over many years from plutonium production and recovery processes. The chemical changes of the organic materials used in the extraction processes and disposed to the tanks have a direct bearing on several specific safety issues, including potential energy releases from these tanks. This paper will give details of a study that is directed towards elucidating thermal and radiological decomposition mechanisms and products of the organic contents of the tanks. The study is being conducted in two parts. The first part, an aging study, will determine kinetics and products of the degradation of a simulated waste subjected to #gamma#-radiation from an external source. Although the simulant will not contain radioactive elements, it will contain other representative inorganic compounds and the primary organic compounds thought to ...

Energy Technology Data Exchange (ETDEWEB)

A model is presented that describes the development of texture during the production process of bake-hardening steel recrystallized in a batch-annealing furnace. Proper conditions are analyzed to generate a pronounced {gamma}-fiber texture and a pancake microstructure that shows superior deep drawability. The {gamma}-fiber texture is assumed to be caused by the interaction between tertiary precipitating aluminum nitride particles and the recrystallization process during heating in the furnace. Deep drawability is presented in terms of the logarithmic {gamma}- and {alpha}-fiber X-ray intensity ratio. The computer simulation of the coupled aluminum nitride precipitation and recrystallization kinetics is based on an iterative procedure. A comparison between simulation results and available experimental data proves the ability of the model to predict the final deep drawability, taking into account the ...

Energy Technology Data Exchange (ETDEWEB)

The refrigerant two-phase flows in a distributor and a simulated plate heat exchanger with a single passage used in a compression-type refrigerator were visualized by real-time neutron radiography. For a distributor, the liquid fraction in the each tube was measured by some image processing method. On the other hand, for a plate heat exchanger, the two-dimensional distribution of void fraction was measured quantitatively by the umbra method. As a result, it was shown that the dynamic behaviors of refrigerant at the inlet of the section strongly affected on the performance, that is, a distribution performance of a distributor and a liquid distribution in a plate heat exchanger. (author)

Energy Technology Data Exchange (ETDEWEB)

Current projections of the response of the biosphere to global climatic change indicate as much as 50% to 90% spatial displacement of extratropical biomes. The mechanism of spatial shift could be dominated by either (1) competitive displacement of northern biomes by southern biomes, or (2) drought-induced dieback of areas susceptible to change. The current suite of global biosphere models cannot distinguish between these two processes, thus determining the need for a mechanistically based biome model. The model is in an early stage of development and will require several enhancements, including explicit simulation of potential evapotranspiration, extension to boreal and tropical biomes, a shift from steady-state to transient dynamics, and validation on other continents.

International Nuclear Information System (INIS)

The most propagated mechanisms of stimulated radiation of electron beam such as Cherenkov one-particle and collective effects, ondulator and magnetic bremsshrahlung radiations, Doppler anomalous effect, Thompson and Raman scattering and radiation are discussed. Relation of spontaneous radiation mechanisms of individual electron and stimulated radiation effects in electron beams has been elucidated, grounds of linear electrodynamics of radiative beam instabilities are stated, and main mechanisms of their nonlinear stabilization are elucidated as well. Various simulated processes in electron beams are considered from the unique point of view using a simple mathematical apparatus and such physical laws as conservation and Newton laws.

British Library Electronic Table of Contents (United Kingdom)

The dependence of the mobility of DNA molecules through an hexagonal array of micropillars on their length and the applied electric field was investigated and it was found that mobility is a nonmonotonic function of their length. Results also revealed that the size dependence of the DNA mobility depends on the applied electric field and there is a crossover around E 25 V/cm for the mobility of l-DNA and T4-DNA. These observations are explained in terms of the diffusion process inside the structure affected by the solvent and are modeled using the Langevin and its corresponding Fokker-Planck equations. The phenomenon is generalized under three regimes in a phase diagram relating the electric field and the DNA lengths. The model and the associated phase diagram described here provide an expl...

Energy Technology Data Exchange (ETDEWEB)

Schemata for modelling combustion processes do not yet include reaction rates for oxygenated fuels like methylal (DMM) which is considered as an additive or replacement for diesel due to its low sooting propensity. Density functional theory (DFT) studies of the possible reaction pathways for different dissociation steps of methylal are presented. Cleavage of a hydrogen bond to the methoxy group or the central carbon atom were simulated at the BLYP/6-311++G{sup **} level of theory. The results are compared to the experiment when dissociating and/or ionising DMM with femtosecond pulses. (author) 1 fig., 1 tab., 1 ref.

British Library Electronic Table of Contents (United Kingdom)

Purpose - The purpose of this paper is to develop pansystems-styled traffics, logistics and knowledge rediscovery. The core logoi are the generalized resources//F* and their circulation//C*. The research presents a new outlook to mathematics, physics, traffic, communication, logistics, KD, internet, computer, translation, simulation, information, life-systems, logic or reasoning, memory or storage, process, transaction, finance, education, inherent, topology, evolution, etc. and then certain mechanism among them and related mutuality can be unveiled. Design/methodology/approach - A flexible combination of philosophy, mathematics and technology is embodied. The paper is an application of pansystems methodology to approach the following topics: pansystems resource, circulation: traffics, log...

Energy Technology Data Exchange (ETDEWEB)

This investigation concerns the nonlinear dynamics of heat transfer from a surface using an upstream eddy promoter. A numerical model is developed for the coupled fluid flow and heat transfer process based on a modified MacCormack scheme. Numerical simulations are carried out to determine the response and heat transfer enhancement due to the promoter. The average heat transfer from a cavity floor is seen to be increased by a factor of approximately five over the unpromoted'' flow. Another interesting feature of the study is the nonlinear viscous flow dynamics from the cylinder-wall interaction which differ significantly from the familiar cylinder-free stream patterns.

International Nuclear Information System (INIS)

In PWR steam-generators, the crevice between tube and tube-support plate tends to fill with porous deposits during operation and acts as a concentration site for chemicals in the boiler water, which may lead to corrosion of the tube and tube-support-plate. The rate of concentration, the magnitude of the concentration factor and the rate of release of solute when conditions change are important parameters for devising strategies to minimize corrosion. Values of these parameters for salt concentration have therefore been measured in a laboratory simulation of the crevice and are used to formulate a model of the concentrating process.

CERN Document Server

We study the production of gravitational waves from cosmic domain walls created during phase transition in the early universe. We investigate the process of formation and evolution of domain walls by running three dimensional lattice simulations. If we introduce an approximate discrete symmetry, walls become metastable and finally disappear. We calculate the spectrum of gravitational waves produced by collapsing metastable domain walls. Extrapolating the numerical results, we find the signal of gravitational waves produced by domain walls whose energy scale is around 10^10-10^12GeV will be observable in the next generation gravitational wave interferometers.

International Nuclear Information System (INIS)

In the procedure of the hydraulic control system analysis, a linearized approximate equation described by the first order term of Taylor's series has been widely used. Such a linearized equation is effective just near the operating point. In this study, the authors estimate computational errors in the process of applying the existing linearized equation stated above. For evaluating the computational accuracy in practical applications of the linearized equations, dynamic behaviors of hydraulic control systems are investigated through simulations with several kinds of representative hydraulic systems and the linearized equations suggested in this study.

International Nuclear Information System (INIS)

The aim of this thesis is the study of new systems devoted to the real time neutron spectrometry and dosimetry. The microelectronics technologies have been used to research a micro system integrating sensor and data processing in real time. The multi range sensor is based on many pair of semiconductor diodes placed face to face and covered by lithium fluoride. The sensor has been designed and its behavior has been simulated. Its operating in reference neutrons beams has been analyzed. (A.L.B.)

Energy Technology Data Exchange (ETDEWEB)

This book of proceedings reports on 7 papers on combustion chemistry and formation of pollutants presented during the workshop organized by the `Combustion and Flames` section of the French society of thermal engineers. The chemistry of combustion is analyzed in various situations such as: turbojet engines, spark ignition engines, industrial burners, gas turbines etc... Numerical simulation is used to understand the physico-chemical processes involved in combustion, to describe the kinetics of oxidation, combustion and flame propagation, and to predict the formation of pollutants. (J.S.)

Energy Technology Data Exchange (ETDEWEB)

Computational fluid dynamics(CFD) code FLUENT was used to simulate the thermal hydraulic processes occurring in conceptual design of the accelerator-driven subcritical reactor(ADSR) liquid lead target. The purpose of the analysis is to investigate the thermal hydraulic characteristics of liquid lead as ADSR target material with various target geometries and injection locations of proton beam. In the calculation analysis, the local temperature of the liquid lead target rises to the boiling temperature very rapidly. When the proton beam is injected from the bottom of the target system, the duration time to reach the boiling temperature is longer and the temperature distribution is flatter than other cases.

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.

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the major features of the advisory tool `TUNDTEMP`, developed to act as a decision support in the continuous steel casting process. `TUNDTEMP` provides a means to predict abnormal phenomena of temperature origin in the casting that may be difficult to foresee in practical situations. The heart of the system is a semi-empirical calculation model that yields an estimate of the evolution of the tundish temperature of the liquid steel on the basis of a few important casting factors. The user interface of the system is to a large extent based on the visual presentation of the simulated results. The system also contains an optional rule based mechanism that provides assistance in the result interpretation and, if wished, linguistically formulates action recommendations. A separate program has been built for the tuning of the calculation model and for maintenance of the system. At the end of the report, the different tuning ...

Science.gov (United States)

Self-amplifying spontaneous radiation free-electron lasers, such as the LCLS or the European X-FEL, rely on the incoherent, spontaneous radiation as the seed for the amplifying process. Though this method overcomes the need for an external seed source one drawback is the incoherence of the effective seed signal. The FEL process allows for a natural growth of the coherence because the radiation phase information is spread out within the bunch due to slippage and diffraction of the radiation field. However, at short wavelengths this spreading is not sufficient to achieve complete coherence. In this presentation we report on the results of numerical simulations of the LCLS X-ray FEL. From the obtained radiation field distribution the coherence properties are extracted to help to characterize the FEL as a light source.

Energy Technology Data Exchange (ETDEWEB)

Equilibrium and energy equations have been developed in describing the solid-fluid transition zone during the melting and solidification of the binary alloys. Due to the existence of the transition region exhibited both solid and fluid phases at the same material point from continuum point of view, mixture theory was utilized to analyze the region. Unlike the Stefan problem, the latent heat due to the phase change appears as a source term in the heat equation. The molten fluid is treated as a thermoviscous and incompressible fluid, whereas the solid is thermoviscoplastic described by the Bodner-Partom/Walker type of constitutive equations. Thermal mechanical behaviors of the solid and the fluid phases are determined separately because of insignificant mechanical interactions between them. Volume fractions of the phases are obtained according to the equilibrium phase diagram. The simulation process of the transition zone and the welding ...

British Library Electronic Table of Contents (United Kingdom)

A mathematical model for heat transfer during solidification in continuous casting of automobile steel, was established on researching under the influence of the solidifying process of bloom quality of CCM in the EAF steelmaking shop, at Shijiazhuang Iron and Steel Co. Ltd. Several steel grades were chosen to research, such as, 40Cr and 42CrMo. According to the results of the high temperature mechanical property tests of blooms, the respective temperature curves for controlling the solidification of different steels were acquired, and a simulating software was developed. The model was verified using two methods, which were bloom pinshooting and surface strand temperature measuring experiments. The model provided references for research on the solidifying process and optimization of a secon...

British Library Electronic Table of Contents (United Kingdom)

Coupled continuous time random walks (CTRWs) model normal and anomalous diffusion of random walkers by taking the sum of random jump lengths dependent on the random waiting times immediately preceding each jump. They are used to simulate diffusion-like processes in econophysics such as stock market fluctuations, where jumps represent financial market microstructure like log returns. In this and many other applications, the magnitude of the largest observations (e.g. a stock market crash) is of considerable importance in quantifying risk. We use a stochastic process called a coupled continuous time random maxima (CTRM) to determine the density governing the maximum jump length of a particle undergoing a CTRW. CTRM are similar to continuous time random walks but track maxima instead of sums....

Energy Technology Data Exchange (ETDEWEB)

An adaptive contingency selection process is set up which produces outage lists in order to guarantee on-line network security control. The quality index system used so far did not detect and reveal all critical variables due to observation problems in the mapping of two functions. The new process uses the results of the outage simulation computing of the system status just past for the drawing up of an up-to-date outage list. A linear correcting function transform the G{sub 2}-values of the standard quality index method - which still incorporate the observation problem effect - into improved values G. Studies which use data from realstic high-voltage networks prove that the detection of critical variables is far superior to ordinary methods. (orig.).

British Library Electronic Table of Contents (United Kingdom)

A model is developed to represent mechanical strain, stress-enhanced dissolution, and shear dilation as innately hysteretic and interlinked processes in rough contacting fractures. The model is incorporated into a numerical simulator designed to examine permeability change and thermal exchange in chemically active and deformable fractured reservoirs. A candidate engineered geothermal reservoir system (EGS) is targeted. The mechanistic model is able to distinguish differences between the evolution of fluid transmission characteristics of (1) small scale, closely spaced fractures, and (2) large-scale, more widely spaced fractures. Alternate realizations of fracture frequency and scale, exhibiting identical initial bulk permeability, lead to significantly different conclusions regarding perme...

Energy Technology Data Exchange (ETDEWEB)

The bulk removal of CO/sub 2/ from industrial gases is a frequently applied process in the field of gas-treating. Usually chemical solvents are used in order to increase both the solvent-loading capacity and the absorption rate. These solvents often are aqueous solutions of alkanolamines. The loaded-liquid is regenerated at high temperatures with the aid steam. In the present study absorption rates are experimentally determined in various mixtures of amines over a wide range of concentrations. Simultaneously, a model was developed for the description of mass transfer accompanied by parallel reversible chemical reactions. The equations of this mass transfer model could not be solved analytically and therefore numerical techniques were used to obtain an exact description of this process. This model also includes the asymptotic situations of homogeneous catalysts and shuttle mechanism for which in the literature several approximate solutions have ...

Energy Technology Data Exchange (ETDEWEB)

A large acceptance, high stopping power, Bragg curve spectrometer has been developed for use in coincidence experiments with heavy ions. The electron collection fields are radial and position information is obtained from a resistive anode. The detector is 60 cm deep and operates at pressures of up to 2.5 atm of P-10 gas. It is mated to a scattering chamber which allows it to be moved out of plane during coincidence measurements. The detector design was aided by the results of computer simulations of the electron collection process in the detector, and of the signal processing in the electronics. The signals from the Bragg curve spectrometer are recorded in a waveform digitizer and the Bragg peak height, range, position and pileup rejection information are determined from software analysis of the recorded signals. Factors limiting the performance of the detector are discussed, and results obtained with the detector are ...

Energy Technology Data Exchange (ETDEWEB)

A new three-dimensional (3D) acoustic modelling method was developed using a first-order hyperbolic wave system which was solved with explicit finite dfferences. The numerical solution of the 3D wave system provides a useful method for simulating evolution of a pressure field corresponding to compressional type waves. Existing two-dimensional (2D) elastic modelling algorithms were modified and fine-tuned for computationally efficient and realistic wave propagation simulations in complex structures. An original formulation of the 3D reverse time migration method was developed which is very accurate, does not suffer from unwanted evenescent energy, can image dips beyond 90{degree}, and does not generate multiple energy. Two case studies were performed that involved steam stimulation projects in the Cold Lake deposit. Simulations were performed during different phases of the steam stimulation process to ...

Energy Technology Data Exchange (ETDEWEB)

This project is sponsored by the United States Department of Energy (DOE) for the ``Engineering Design and Analysis of Advanced Physical Fine Coal Cleaning Technologies: The major goal is to provide the simulation tools for modeling both conventional and advanced coal cleaning technologies. This DOE project is part of a major research initiative by the Pittsburgh Energy Technology Center (PETC) aimed at advancing three advanced coal cleaning technologies-heavy-liquid cycloning, selective agglomeration, and advanced froth flotation through the proof-of-concept (POC) level. The commercially available ASPEN PLUS process simulation package will be extended to handle coal cleaning applications. Algorithms for predicting the process performance, equipment size, and flowsheet economics of commercial coal cleaning devices and related ancillary equipment will be incorporated into the coal cleaning ...

Energy Technology Data Exchange (ETDEWEB)

This paper deals with the externally coal-fired combined cycle (EFCC). A process simulation for different configurations of the EFCC-process is carried out as well as an investigation of the effect of the key parameters such as the gas turbine inlet temperature and the compressor intake airflow. The results show a promising potential of the efficiency. One component of this combined gas and steam turbine cycle is a high temperature heat exchanger that has to withstand the extrem chemical and thermal operating conditions. Fibre reinforced ceramics and combinations of them with monolithic ceramics seem to be the most promising materials for this application. A cost estimating of the EFCC-process shows that a competitive operation should be possible. (orig.) [Deutsch] Die Ergebnisse der Prozesssimulationen weisen ein vielversprechendes Wirkungsgradpotential des extern kohlebefeuerten Gasturbinenprozesses ...

Energy Technology Data Exchange (ETDEWEB)

The E and P industry has high levels of uncertainty and risk, which oil companies attempt to quantify before embarking on each individual E and P project. However, the actual return on investment often falls well short of the hurdle rate. This discrepancy has been attributed to systemic limitations in decision analysis processes and workflow, which result in repeated underestimation of risk and overestimation of the predicted production of the project. Well designed decision analysis processes in association with clearly defined, multi-scenario analyses of significant technical uncertainties are required. However, simulation of these uncertainties is not realistic given the performance and infrastructure limitations of conventional technology (Begg et al., 2001; Floris and Peersmann, 2000). During the past five years, more than 20 companies have attempted to map the requirements of new technology that is needed to improve ...

International Nuclear Information System (INIS)

Full text of publication follows: The TUV NORD e.V. is an independent Technical Support Organisation (TSO) performing safety assessments in almost every field of technology. In nuclear safety the TUV can look back on more than 40 years of experience. In the last years in Germany PWR safety analyses were focussed on boron dilution events with the potential of reactivity transients. The possibility of coolant with a low boron concentration collected in localized areas of the reactor coolant system (RCS) can be caused by injection of coolant with less boron content from interfacing systems (external dilution) as well as separation of borated reactor coolant into highly concentrated and diluted fractions (inherent dilution). Inherent dilution can e.g. occur after reflux-condenser heat transfer after a small break loss of coolant accident (SBLOCA) with a limited operability of the emergency core cooling (ECC) systems. The TUV Nord e.V. was charged by German supervisory authorities with the ...

Energy Technology Data Exchange (ETDEWEB)

The object of this study was to identify those areas in California where synthetic fuel-fired power plants could be sited in the 1990 time frame, from an air quality perspective. The synfuel-fired power plants considered in this new study were 500 Mw methanol-fired combined cycle (MFCC) and 500 Mw integrated gasifier combined-cycle (IGCC) units. For comparison purposes, 500 Mw direct coal-fired boilers and 500 Mw natural gas-fired combined-cycle units were also considered. Staff did not attempt to locate plants at any specific sites, but relied primarily upon a regional countywide analysis. The study provides an approximation, for planning purposes, of a reasonable limit of the state's power plant siting capacity, given the plant types and sizes, conditions, and assumptions specified. The study shows that local emission limitations often preclude certain types of power plants (particularly direct-fired coal plants) even when they are equipped with Best ...

International Nuclear Information System (INIS)

Full text: Radiotherapy treatment planning (RTP) relies heavily on medical imaging. Until recently, the most important planning tool was the treatment simulator. The kilovoltage radiographic capabilities in a treatment simulator enabled the boundaries of treatment fields to be visualized with respect to bony anatomic landmarks. Perhaps the most important advance in treatment planning in recent years is the ability to visualize the passage of the beams with respect to a more accurate geometrical representation of the tumor and other soft tissue structures. This 'virtual simulation' uses a computer-based representation of a patient to determine the extent of the disease and the location of radiation sensitive normal tissue. Computer tomographic (CT) imaging produces a high-resolution three-dimensional representation of anatomy that can be correlated with other image sets such as magnetic resonance images (MRI) of function. ...

International Nuclear Information System (INIS)

The commercial Modular High Temperature Gas-Cooled Reactor (MHTGR) achieves improved reactor safety performance and reliability by utilizing an integrated sequence of completely passive thermal storage and heat transfer mechanisms to reject decay heat in the event that all its active cooling systems fail to operate. During such events, the initial heatup transient in the core is followed by a quasi-steady state cooldown process which, if uninterrupted, can continue for several days. A buoyancy-driven natural convection cooling system called the RCCS facilitates the continuous heat removal by circulating ambient air through the reactor cavity, where it is heated and then exhausted to the outside environment. The peak thermal load on the RCCS occurs approximately at the time that the vessel reaches its highest temperature. To confirm the adequacy of the RCCS design, detailed analytical models were developed to simulate the decay heat removal ...

International Nuclear Information System (INIS)

During the last years one focus of German PWR safety analysis was boron dilution events with the potential of reactivity transients. Coolant with a low boron concentration could be collected in localized areas of the reactor coolant system e.g. by separation of borated reactor coolant into highly concentrated and diluted fractions (inherent dilution) which can occur during reflux- condenser heat transfer after a small break loss of coolant accident with a limited availability of the emergency core cooling systems. The TUeV NORD SysTec was charged by German supervisory authorities with the assessment of the safety analyses of boron dilution events presented by the utilities. These analyses are based on the simulation of boron dilution and transport processes in conjunction with a number of dedicated experiments. The analyses shall demonstrate that boron dilution events cannot lead to recriticality of the core. Hence the boron concentration at ...

Energy Technology Data Exchange (ETDEWEB)

The UNSAT-H model was developed at Pacific Northwest National Laboratory (PNNL) to assess the water dynamics of arid sites and, in particular, estimate recharge fluxes for scenarios pertinent to waste disposal facilities. During the last 4 years, the UNSAT-H model received support from the Immobilized Waste Program (IWP) of the Hanford Site's River Protection Project. This program is designing and assessing the performance of on-site disposal facilities to receive radioactive wastes that are currently stored in single- and double-shell tanks at the Hanford Site (LMHC 1999). The IWP is interested in estimates of recharge rates for current conditions and long-term scenarios involving the vadose zone disposal of tank wastes. Simulation modeling with UNSAT-H is one of the methods being used to provide those estimates (e.g., Rockhold et al. 1995; Fayer et al. 1999). To achieve the above goals for assessing water dynamics and estimating recharge rates, the ...

International Nuclear Information System (INIS)

With accurate calculation algorithms in inverse planning for beamlet-based intensity modulated radiotherapy (IMRT), it takes time to calculate the dose matrix, which represents the dose distribution of each beamlet element to each voxel for unit fluence. To reduce the calculation time, coarse or approximate algorithms are often a choice, but this results in a final dose distribution that cannot reflect the real value. In addition, it is necessary to test if a coarse algorithm is capable of calculating the dose matrix of beamlets. In this work, simulated dynamics optimization algorithm was applied to optimize the segment weight to minish the dose error from the dose matrix calculation. After calculating the dose matrix by ray-tracing algorithm which takes into account just the primary component of absorbed dose, the original beam profile intensity distribution was optimized by using the simulated dynamics algorithm. Before segmentation, the ...

International Nuclear Information System (INIS)

Bone images obtained by single exposure dual energy subtraction with computed radiography, a new image processing method, were evaluated for the detectability of calcification in lung nodules in both phantom and clinical studies. In the phantom study, five simulated nodules containing known and uniformly distributed amounts of calcium hydroxide were placed in a human chest phantom and images were obtained the following five techniques: 1) conventional radiography (CXR), 2) low kV conventional radiography (Low), 3) Fuji computed radiography (FCR), 4) bone images with conventional singles exposure energy subtraction (ES) and 5) bone image with fine single exposure energy subtraction (FES). The detectability of calcification in the simulated nodules was evaluated by six radiologists using ROC analysis and two-way analysis of variance. In the clinical study, images of 42 lung nodules (21 calcified lung nodules and 21 ...

International Nuclear Information System (INIS)

The present situation of the researches that have been made for predicting the process and range of diffusion of warm drain is reviewed. This review is divided into eight sections. The first section deals with the present situation of warm drain from power plants. For the establishment of drainage standard, there are many difficult problems to be solved because water temperature differs in its nature from other regulation items. In the second section, the process of diffusion and cooling of warm drain is explained. The third section deals with the diffusion characteristics of warm drain in Japanese coastal sea due to water temperature. Two types of diffusion are known. One is dominant irregular current, and the other is periodical reciprocating stream. The fourth section deals with the methods of prediction of diffusion. Research methods and simulation models are described. The fifth section deals with the prediction with ...

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 viscoplasticity or viscoelasticity. The constitutive ...

Energy Technology Data Exchange (ETDEWEB)

Vertical thin film evaporators have been used to concentrate and dry solutions because their rotating swing blades prevent scale from being deposited on the heated surfaces. Powdering capacity of the vertical thin film evaporator was examined experimentally for drying applications of radioactive liquid waste generated from nuclear power plants. As a result, it was found that the powdering capacity increased with the blade rotation, changing significantly in the low ratational region and scarcely in the high rotational region. The powdering capacity in the high rotational region was restricted by the lack of heat flux which was theoretically evaluated for the concentrating process. As the critical factor in the low rotational region was not clear, a visual test apparatus was made to observe flow patterns in the evaporator, and a powdering model was obtained. This model showed that powdering process was obstructed when the liquid film lost its ...

Energy Technology Data Exchange (ETDEWEB)

SRS high-level radioactive waste tanks will not experience erosion corrosion to any significant degree during slurry pump operations. Erosion corrosion in carbon steel structures at reported pump discharge velocities is dominated by electrochemical (corrosion) processes. Interruption of those processes, as by the addition of corrosion inhibitors, sharply reduces the rate of metal loss from erosion corrosion. The well-inhibited SRS waste tanks have a near-zero general corrosion rate, and therefore will be essentially immune to erosion corrosion. The experimental data on carbon steel erosion corrosion most relevant to SRS operations was obtained at the Hanford Site on simulated Purex waste. A metal loss rate of 2.4 mils per year was measured at a temperature of 102 C and a slurry velocity comparable to calculated SRS slurry velocities on ground specimens of the same carbon steel used in SRS waste tanks. Based on these data ...

Energy Technology Data Exchange (ETDEWEB)

Commercially available melter technologies were tested during 1994-95 as part of a multiphase program to test candidate technologies for vitrification of the low-level waste (LLW) stream to be derived from retrieval and pretreatment of Hanford Site tank wastes. Seven vendors were selected for Phase 1 testing to demonstrate vitrification of a high sodium content liquid LLW simulant. The tested melter technologies included four Joule-heated melters, a carbon electrode melter, a combustion melter, and a plasma melter. Various dry and slurry melter feed preparation processes were also tested. Various feed material samples, product glass samples, and process offgas streams were characterized to provide data for evaluation of process decontamination factors and material mass balances for each vitrification technology. This report describes the melter mass balance evaluations and results for six of the Phase 1 ...

Energy Technology Data Exchange (ETDEWEB)

The proper selection of materials of construction is necessary to provide process equipment with optimum performance and corrosion resistance. If properly chosen, the selected material should deteriorate at a uniform, predictable rate, which will allow for maintenance or replacement at scheduled intervals. This concept of risk assessment for predictive maintenance is a minimum requirement for proper materials selection. Materials selection is based on prior service history, field corrosion tests, pilot-plant tests, and laboratory bench-top tests--in that relative order of usefulness. Corrosion test methods are usually divided into two groups: laboratory and field (plant-site) tests. The main difference between the two is that field test specimens are exposed to actual process conditions will all of the variables involved, while laboratory tests are a simulation of field conditions, even if actual ...

CERN Document Server

The collapse of a massive star's core, followed by a neutrino-driven, asymmetric supernova explosion, can naturally lead to pulsar recoils and neutron star kicks. Here, we present a two-dimensional, radiation-hydrodynamic simulation in which core collapse leads to significant acceleration of a fully-formed, nascent neutron star (NS) via an induced, neutrino-driven explosion. During the explosion, a ~10% anisotropy in the low-mass, high-velocity ejecta lead to recoil of the high-mass neutron star. At the end of our simulation, the NS has achieved a velocity of ~150 km s$^{-1}$ and is accelerating at ~350 km s$^{-2}$, but has yet to reach the ballistic regime. The recoil is due almost entirely to hydrodynamical processes, with anisotropic neutrino emission contributing less than 2% to the overall kick magnitude. Since the observed distribution of neutron star kick velocities peaks at ~300-400 km s$^{-1}$, recoil due to ...

Energy Technology Data Exchange (ETDEWEB)

A helical cooling channel (HCC) has been proposed to quickly reduce the six-dimensional phase space of muon beams for muon colliders, neutrino factories, and intense muon sources. The HCC is composed of a series of RF cavities filled with dense hydrogen gas that acts as the energy absorber for ionization cooling and suppresses RF breakdown in the cavities. Magnetic solenoidal, helical dipole, and helical quadrupole coils outside of the RF cavities provide the focusing and dispersion needed for the emittance exchange for the beam as it follows a helical equilibrium orbit down the HCC. In the work presented here, two Monte Carlo programs have been developed to simulate a HCC to compare with the analytic predictions and to begin the process of optimizing practical designs that could be built in the near future. We discuss the programs, the comparisons with the analytical theory, and the prospects for a HCC design with the capability to reduce the ...

Energy Technology Data Exchange (ETDEWEB)

Nuclear physics accelerators are powered by microwaves which must travel in waveguides between room-temperature sources and the cryogenic accelerator structures. The ohmic heat load from the microwaves is affected by the temperature-dependent surface resistance and in turn affects the cryogenic thermal conduction problem. Integrated EM & thermal analysis of this difficult non-linear problem is now possible with the VORPAL finite-difference time-domain simulation tool. We highlight thermal benchmarking work with a complex HOM feed-through geometry, done in collaboration with researchers at the Thomas Jefferson National Accelerator Laboratory, and discuss upcoming design studies with this emerging tool. This work is part of an effort to generalize the VORPAL framework to include generalized PDE capabilities, for wider multi-physics capabilities in the accelerator, vacuum electronics, plasma processing and fusion R&D fields, and we will ...

Energy Technology Data Exchange (ETDEWEB)

The rates of hydrogen release from simulated high-level liquid waste (SHLLW) during irradiation of {sup 60}Co {gamma}-rays have been studied using a laboratory-scale apparatus. The SHLLW used was made up of 28 different metal elements, the concentrations of which were determined from a computed data (ORIGEN-2) for a Purex spent fuel (burn-up of 4.5 GWd/t, cooling time of 4 years) except for those of corrosion products (Fe, Cr and Ni) and of chemical process additive (P). The nitrate ion concentration of the SHLLW was 4.97 M. The G-value of hydrogen release was 0.0164 for stirred conditions, but for nonstirred conditions with dose rate : 2.8 kGy/h and with the SHLLW solution height more than 8 cm, the following relation was found between the G-value and the solution height (d cm); G(H{sub 2}) = 0.100 d{sup -1.6}. The G-values of oxygen and nitrogen releases were also determined. (author)

International Nuclear Information System (INIS)

We discuss atomistic simulations of ion implantation and annealing of Si over a wide range of ion dose and substrate temperatures. The DADOS Monte Carlo model has been extended to include the formation of amorphous regions, and this allows simulations of dopant diffusion at high doses. As the dose of ions increases, the amorphous regions formed by cascades eventually overlap, and a continuous amorphous layer is formed. In that case, most of the excess interstitials generated by the implantation are swept to the surface as the amorphous layer regrows, and do not diffuse in the crystalline region. This process reduces the amount of transient enhanced diffusion (TED) during annealing. This model also reproduces the dynamic annealing during high temperature implants. In this case, the local amorphous regions regrow as the implant proceeds, without the formation of a continuous amorphous layer. For sufficiently high ...

Energy Technology Data Exchange (ETDEWEB)

Polychlorinated dibenzo-p-dioxins and dibenzo-furans form a family of more than 200 compounds which are relatively stable in the biosphere and tend to accumulate in the human body. The tetra- to hexa-chlorinated dioxins and furans are considered highly toxic. To facilitate the assessment of the total toxicity of dioxin and furan mixtures, the estimated toxic effects of the individual compounds relative to the 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) were introduced as Toxic Equivalent Factors which yield, when multiplied with the respective concentrations, the Toxic Equivalent (TE) of the mixture. Toxic dioxins and furans are unintentionally formed in a number of industrial combustion processes such as waste incineration and iron ore sintering, in the chemical industry and in household heating. To keep the emissions as low as possible, off-gas clearing systems for the collection of dioxins and furans are increasingly prescribed by the authorities. In addition, ...

KoreaScience (Korea)

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KoreaScience (Korea)

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CERN Document Server

Multiphase reacting flows

KoreaScience (Korea)

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Science.gov (United States)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

The role played by planetary boundary layer (PBL) in the development and evolution of a severe convective storm is studied by means of meso-scale modeling and surface and upper air observations. The severe convective precipitation event that occurred on 14 September 1999 in the northeast of the Iberian Peninsula was simulated by means of the mesoscale model MM5 (version 3) using three different PBL schemes. The numerical results show a large impact of the PBL schemes on the precipitation fields associated to the convective storm. The schemes are based on different physical assumptions: the nonlocal first order medium-range forecast (MRF) and blackadar (BLA) scheme and the local, one-and-a-half order ETA scheme. Surface and radar observations are used to validate the model results. The comparison focuses on three aspects: the evolution, the spatial distribution and the 24-h accumulated precipitation. The comparison with rain gauge observations shows that the MRF, ...

Science.gov (United States)

... DARPA UUV and the UUV support simulator. ... Modular connections for robot arm manipulators ... Intelligent mobile robots will be performing many ...

Energy Technology Data Exchange (ETDEWEB)

In this study we tried to develop the long-range transport system and find the way to prevent from the radiological emergency risk. For the study, meteorological forecast system in Korea Meteorological Administration is investigated. Numerical simulation is also carried out by the long-range transport model and Vis-5D. We surveyed the emergency preparedness for nuclear accidents which were ARAC in USA, RODOS in Europe and WSPEED in Japan and then investigated the processing of medium- and long-range atmospheric diffusion modeling system. We also studied on the application of KMA/NWPD model which are GDAPS and RDAPS. In the future, it is necessary to produce to the high resolution meteorological data from KMA/NWPD for the development of medium- and long-range atmospheric diffusion modeling system and construct the integrated system for data processing in real time. It was simulated by using micro-scale ...

Energy Technology Data Exchange (ETDEWEB)

Data produced by large scale scientific simulations, experiments, and observations can easily reach tera-bytes in size. The ability to examine data-sets of this magnitude, even in moderate detail, is problematic at best. Generally this scientific data consists of multivariate field quantities with complex inter-variable correlations and spatial-temporal structure. To provide scientists and engineers with the ability to explore and analyze such data sets we are using a twofold approach. First, we model the data with the objective of creating a compressed yet manageable representation. Second, with that compressed representation, we provide the user with the ability to query the resulting approximation to obtain approximate yet sufficient answers; a process called adhoc querying. This paper is concerned with a wavelet modeling technique that seeks to capture the important physical characteristics of the target scientific data. Our approach is ...

Energy Technology Data Exchange (ETDEWEB)

The generation of thermal energy is the great importance for the agribusiness of dairy industry to conservation the quality of milk, taking into account that the electricity is the main source currently used for the thermal energy input. The small agribusiness dairy industry currently practiced in Brazil faces several problems related to the cost of electricity and the distance of rural properties of networks of power. In the current scenario of Brazilian dairy production, there is need for the generation of cold for the milk cooling, and also the heat for the production of hot water around 50 deg C to 60 deg C and also for cleaning of equipment used for milk production and processing. The main objective of this study is the modeling and simulation of integrated recovery process of solid waste, effluents and bioconversion. The specific project objectives are: comparison study of options and technological routes of low cost ...

International Nuclear Information System (INIS)

The aim of the work in this thesis is to investigate the convective and diffusive transport in the TM chemistry transport model, and to investigate some aspects of the consequences for NOx. The large inaccuracy and uncertainty in the description of processes like convection and turbulent diffusion, the strong dependence of the radiative forcing of ozone on its vertical distribution, and the strong dependence of the ozone production on the distribution of NOx, are the main motivation. The availability of the ERA-40 data, where convective data and vertical diffusion coefficients are archived, allows a study of the effect of different convective mass flux sets, and different vertical diffusion coefficients on the model-simulated distribution of tracers. In this thesis the following questions are addressed : (1) How large is the sensitivity of the (model simulated) distribution of ozone and nitrogen oxides on (the) convection ...

Energy Technology Data Exchange (ETDEWEB)

A new methodology for three-dimensional (3-D) numerical modeling of the continuous steel casting process is presented and evaluated. The results are compared with available experimental data obtained in a water-oil mold model for various flow rates and immersion depths of the submerged entry nozzle. The water-oil interface pattern at the top of the mold is also investigated. Wave formation and evolution in time is simulated with a volume tracking method. The predicted flow field inside the mold exhibits quite satisfactory agreement with the corresponding measurements, whereas some quantitative differences are observed referring to the final wave amplitude at low casting speeds. Conclusions of scientific and engineering importance concerning both the computer algorithm and the mold performance are also drawn.

International Nuclear Information System (INIS)

Smoothing of laser beam non-uniformities using gas jets has been studied. The experiment has been performed with the PALS (Prague Asterix Laser System) laser working at 0.44 ?m with an intensity of about 1015 W/cm2. The laser beam has been split in two by a prism thus creating an artificial large-scale non-uniformity (? 90 ?m). We recorded time resolved and static images of laser-gas jet interaction with and without an Al target. Multi 1-dimensional and 2-dimensional simulations show that such interaction acts redistributing the over-intensities over larger surface. This effect has to be attributed to ionization processes with consequent laser beam refraction. Results show that Argon gas jet produces a strong refraction of the laser beam thus strongly reducing the initial two spots separation. (authors)

International Nuclear Information System (INIS)

The aim of the safety calculation is to quantify through numerical modelling the radiological impact (molar flow, human dose) of a potential repository for radioactive waste on the Meuse/Haute Marne site at Bure. A selection process is underway for safety scenarios and their phenomenological and numerical conceptual models upstream from the safety calculation. This involves defining and quantifying the geometric and dimensional representations of the repository for each scenario plus the physical, mathematical and numerical models that reflect its behaviour and the uncertainties associated with all the parameters required to quantify the impact. A summary will be given of these various aspects. The numerical simulations are then performed on the Alliances platform which integrates the various computer codes required for the physical representation of the system. (authors)

International Nuclear Information System (INIS)

The difficulty and unstability of the parameter estimation of mass action model for radioimmunoassay are the major obstacles to its application in routine work. A unique robust curve fitting method for the mass action model was introduced. large numbers of simulated data were generated with Monte Carlo method to compare the accuracy and robustness of the robust fitting and the least squre fitting (Marquardt method) of the mass action model. The results demonstrated that the new robusst method significantly increased the accuracy and reliability of data processing with the mass action model. It also markedly reduced the influence of outliers in the fitting of RIA data, and it was always 'convergent'. This robust method could also be applied to other mathematical models which can be transformed into high degree equations and no initial estimates are needed for curve fitting.

CERN Document Server

Significant research has been carried out in the recent years for generating systems exhibiting intelligence for realizing optimized routing in networks. In this paper, a grade based twolevel based node selection method along with Particle Swarm Optimization (PSO) technique is proposed. It assumes that the nodes are intelligent and there exist a knowledge base about the environment in their local memory. There are two levels for approaching the effective route selection process through grading. At the first level, grade based selection is applied and at the second level, the optimum path is explored using PSO. The simulation has been carried out on different topological structures and it is observed that a graded network produces a significant reduction in number of iteration to arrive at the optimal path selection.

Energy Technology Data Exchange (ETDEWEB)

Combined gas and steam turbine processes based on direct coal firing show a high thermal efficiency. At RWTH Aachen, University of Technology, an experimental test furnace has been built to investigate the pressurized pulverized coal combustion (PPCC). The PPCC-facility has been constructed as a slag tap furnace. Particles hitting the walls at temperatures above the melting point cause slagging depositions and create a film flowing down the reactor walls. As a part of the PPCC-program different mathematical models have been developed and implemented into the CFD-code FLUENT to predict the behavior of slag films at the furnace walls. Numerical strategies and the mathematical models used are described in detail. 12 refs., 9 figs.

International Nuclear Information System (INIS)

An evolutionary model of dynamical processes in protostellar disks is described and illustrated with graphs of typical results. The effective transport mechanisms are discussed, including thermal convection, nonaxisymmetric gravitational instabilities in the outer regions of disks, and wave propagation. Consideration is then given to the stages of dynamical evolution, FU Ori outburst phenomena, unsteady accretion-disk flows, and nonlinear feedback as a mechanism to modulate mass transfer. The simulations show that mass redistribution is determined by angular-momentum transfer, which in turn is regulated by the effective viscosity generated by convectively driven turbulence. Significant mass transfer occurs as a result of mixing of infalling material with disk gas and is affected by the tidal torque associated with the growth of nonaxisymmetric disturbances in the outer disk. The time scale for disk evolution is found to be about 1 Myr. 72 refs.

Energy Technology Data Exchange (ETDEWEB)

In general, macroscopic material failure is a manifestation of irreversible changes at the microscopic level. Many tissues, which may appear to be macroscopically homogeneous, are, at a fundamental microscopic level, a composite material. For example, cornea is composed of a hyaluronic acid matrix in which layers of collagen fibers are overlaid in a crossing pattern. The points where the collagen fibers intersect are potential nucleation sites for microscopic defects, which under the action of tensile stress, nucleate, grow and coalesce to form macroscopic failure planes, or spall planes. Using a model based on microstructural evolution, this paper examines the failure process during photoablation. Specifically, the paper describes a physically motivated, micromechanical model based on the nucleation and growth of spherical voids. This model is then used to simulate photoablation of cornea. Potential for using this model to predict the stress ...

British Library Electronic Table of Contents (United Kingdom)

In situ composite coating of hydroxyapatite (HA)/TiO2 were produced on titanium (Ti) substrate by micro-arc oxidation coupled with electrophoretic deposition (MAO&EPD) technique with different concentrations of HA particles in the 0.2M NaOH electrolyte solution. The surface morphology and chemical composition of the hybrid coating were effected by HA concentration. The amount of HA particles incorporated into coating layer increased with increasing HA concentration used in the electrolyte solution. The corrosion behavior of the coating layer in simulated body fluids (SBF) was evaluated using a potentiodynamic polarization test. The corrosion resistance of the coated sample was increased compared to the untreated Ti sample. The in vitro bioactivity assessment showed that the MAO&EPD treated...

British Library Electronic Table of Contents (United Kingdom)

Regional Ocean Modeling System (ROMS v 3.0), a three-dimensional numerical ocean model, was previously enhanced for shallow water applications by including wave-induced radiation stress forcing provided through coupling to wave propagation models (SWAN, REF/DIF). This enhancement made it suitable for surf zone applications as demonstrated using examples of obliquely incident waves on a planar beach and rip current formation in longshore bar trough morphology (Haas and Warner, 2009). In this contribution, we present an update to the coupled model which implements a wave roller model and also a modified method of the radiation stress term based on Mellor (2008, 2011a,b,in press) that includes a vertical distribution which better simulates non-conservative (i.e., wave breaking) processes and ...

International Nuclear Information System (INIS)

This report summarizes the results of a research programme which involves the development of a laboratory experimental facility for the simulation and study of hydro-thermo-mechanical processes in saturated geomaterials with low permeability. The experimentation involves a synthetic cement based porous material made of cement grout which possesses permeabilities in the range of dense unfractured sandstones or shale. Specially manufactured pore-pressure transducers were installed within the cylindrical block at locations adjacent to a plane free boundary. The block was saturated with the periodic application of a vacuum. In its saturated state the plane boundary of the block was subjected to heating via a circular heater the temperature of which was maintained constant. The resulting pore pressure generation along with temperature at these locations was monitored continuously. The results of a series of experiments are documented and further ...

International Nuclear Information System (INIS)

The total hemispherical emittance of an oxide film that formed on 6061-T6 aluminium alloy parts in the Tower Shielding Reactor-II at Oak Ridge National Laboratory was measured from 295 to 773 K using an emissometer and/or a calorimeter. The emittance of this film was critically needed for heat transfer calculations in a simulated loss-of-coolant accident of the reactor. X-ray diffraction analysis identified the film as boehmite (Al_2O_3 x H_2O), which dehydrated to alumina (Al_2O_3) upon heating above 473 K. The measured emittances for the alumina film are in excellent agreement with published values for anodized aluminum films and for bulk alumina. Published values of the emittance of boehmite could not be found for comparison, but evidence is presented that some anodization processes for aluminum yield boehmite and not alumina films.

International Nuclear Information System (INIS)

Electron simulated desorption of anions from CFCl_3 and CF_2Cl_2 condensed on an Au substrate is studied in the energy range 0-15 eV. The negative fragments are recorded mass spectro metrically as the function of the incident electron energy. Below 10 eV we observe anion desorption via pronounced resonance profiles which are characteristic for dissociative electron attachment (DA) while the continuous rise of the signal at higher energies accounts for dipolar dissociation (DD) and processes involving secondary electrons from the metallic substrate. For both compounds F"- and Cl"- are the only fragment anions we could observe. (author).

British Library Electronic Table of Contents (United Kingdom)

A mathematical model was developed to predict a moisture content profile during the thick layer re-wetting process of brown rice unpackaged and packaged with low density polyethylene (LDPE) and polybutylene terephthalate (PBT) films. Model validation was carried out by comparing predicted with measured moisture content derived from relative humidity data obtained from the brown rice re-wetting test for 6days at 25degreeC and 90% RH. The moisture standard errors of the model validation for brown rice packaged in LDPE and PBT films were 0.08% wet basis (wb) and 0.11%wb, respectively. It was concluded that the proposed re-wetting model could successfully describe the thick layer re-wetting of brown rice under the experimental conditions. Using this model, re-wetting simulations were carried o...

Energy Technology Data Exchange (ETDEWEB)

The experimental foam treatments conducted on two production wells, each in a different miscible flood pool, were described, including aspects of the laboratory work, numerical coning simulation, well selection process and foam placement strategy. One of the wells was injected with a foam-forming surfactant, as well as with a surface-generated preformed foam. Neither of these treatments had any effect on the performance of this well. In the other well, preformed foam treatment was successful in reducing gas-oil ratio, resulting in improved oil production over a 14-month period. Future foam injection projects are being planned, based on the experiences gained in this field experiment. 13 refs., 21 figs.

Energy Technology Data Exchange (ETDEWEB)

Rafting of the {gamma}/{gamma}{prime} morphology of nickel-base superalloys is a well-known phenomenon during high-temperature deformation. The initial stages of this type of directional coarsening were modeled two-dimensionally by the method of finite elements (FEs) using an energy-perturbation approach. In addition to the elastic energy density, the effect of the local difference of the hydrostatic stresses in {gamma} and {gamma}{prime} in combination with the different lattice parameters of the two phases was considered in the calculations as a further driving force. From the results of modeling, the deformation-induced internal stresses and strains were determined and used to evaluate the direction-dependent lattice parameters and lattice misfits of the two phases. The results agree well with experimentally determined values.

Science.gov (United States)

In order to increase the speed of photoelectric conversion, a linear CCD is applied as the photoelectric converter instead of the traditional photodiode. A white LED is used as the light source of the system. The color information of the urine test strip is transferred into the CCD through a reflecting optical system. It is then converted to digital signals by an A/D converter. The test results of urine analysis are obtained by a data processing system. An ARM microprocessor is selected as the CPU of the system and a CPLD is employed to provide a driving timing for the CCD drive and the A/D converter. Active HDL7.2 and Verilog HDL are used to simulate the driving timing of the CPLD. Experimental results show that the correctness rate of the test results is better than 90%. The system satisfies the requirements of the color information collection of urine analyzer.