International Nuclear Information System (INIS)
Minh, Nguyen Nguyen; Aoyagi, Yukio; Kanazu, Tsutomu; Ohtomo, Keizo; Matsumoto, Yasuaki
2000-01-01
Dynamic numerical simulation of a coupled soil-structure system by non-linear finite element method is presented. The target structure is the underground duct-type structure for emergency services in nuclear power plants. By appropriately modeling, including refinements in dynamic soil model and introduction of interface element, etc., the simulated results are in a very good agreement with the experimental results in terms of dynamic amplitudes and damaging process. A simple mesh generation program specific for the system with optimization concern is made. Some issues on computational aspects are then addressed. (author)
Directory of Open Access Journals (Sweden)
Yoon Young Choi
Full Text Available Although changing a lymph node staging system from an anatomically based system to a numerically based system in gastric cancer offers better prognostic performance, several problems can arise: it does not offer information on the anatomical extent of disease and cannot represent the extent of lymph node dissection. The purpose of this study was to discover an alternative lymph node staging system for gastric cancer. Data from 6025 patients who underwent gastrectomy for primary gastric cancer between January 2000 and December 2010 were reviewed. The lymph node groups were reclassified into lesser-curvature, greater-curvature, and extra-perigastric groups. Presence of any metastatic lymph node in one group was considered positive. Lymph node groups were further stratified into four (new N0-new N3 according to the number of positive lymph node groups. Survival outcomes with this new N staging were compared with those of the current TNM system. For validation, two centers in Japan (large center, n = 3443; medium center, n = 560 were invited. Even among the same pN stages, the more advanced new N stage showed worse prognosis, indicating that the anatomical extent of metastatic lymph nodes is important. The prognostic performance of the new staging system was as good as that of the current TNM system for overall advanced gastric cancer as well as lymph node-positive gastric cancer (Harrell C-index was 0.799, 0.726, and 0.703 in current TNM and 0.799, 0.727, and 0.703 in new TNM stage. Validation sets supported these outcomes. The new N staging system demonstrated prognostic performance equal to that of the current TNM system and could thus be used as an alternative.
Testability of numerical systems
International Nuclear Information System (INIS)
Soulas, B.
1992-01-01
In order to face up to the growing complexity of systems, the authors undertook to define a new approach for the qualification of systems. This approach is based on the concept of Testability which, supported by system modelization, validation and verification methods and tools, would allow Integrated Qualification process, applied throughout the life-span of systems. The general principles of this approach are introduced in the general case of numerical systems; in particular, this presentation points out the difference between the specification activity and the modelization and validation activity. This approach is illustrated firstly by the study of a global system and then by case of communication protocol as the software point of view. Finally MODEL which support this approach is described. MODEL tool is a commercial tool providing modelization and validation techniques based on Petri Nets with triple extension: Predicate/Transition, Timed and Stochastic Petri Nets
Atack, John M; Yang, Yuedong; Jennings, Michael P
2018-01-01
Abstract Many bacteria utilize simple DNA sequence repeats as a mechanism to randomly switch genes on and off. This process is called phase variation. Several phase-variable N6-adenine DNA-methyltransferases from Type III restriction-modification systems have been reported in bacterial pathogens. Random switching of DNA methyltransferases changes the global DNA methylation pattern, leading to changes in gene expression. These epigenetic regulatory systems are called phasevarions — phase-variable regulons. The extent of these phase-variable genes in the bacterial kingdom is unknown. Here, we interrogated a database of restriction-modification systems, REBASE, by searching for all simple DNA sequence repeats in mod genes that encode Type III N6-adenine DNA-methyltransferases. We report that 17.4% of Type III mod genes (662/3805) contain simple sequence repeats. Of these, only one-fifth have been previously identified. The newly discovered examples are widely distributed and include many examples in opportunistic pathogens as well as in environmental species. In many cases, multiple phasevarions exist in one genome, with examples of up to 4 independent phasevarions in some species. We found several new types of phase-variable mod genes, including the first example of a phase-variable methyltransferase in pathogenic Escherichia coli. Phasevarions are a common epigenetic regulation contingency strategy used by both pathogenic and non-pathogenic bacteria. PMID:29554328
Numerical analysis of systems of ordinary and stochastic differential equations
Artemiev, S S
1997-01-01
This text deals with numerical analysis of systems of both ordinary and stochastic differential equations. It covers numerical solution problems of the Cauchy problem for stiff ordinary differential equations (ODE) systems by Rosenbrock-type methods (RTMs).
Relativistic positioning systems: Numerical simulations
Puchades Colmenero, Neus
The position of users located on the Earth's surface or near it may be found with the classic positioning systems (CPS). Certain information broadcast by satellites of global navigation systems, as GPS and GALILEO, may be used for positioning. The CPS are based on the Newtonian formalism, although relativistic post-Newtonian corrections are done when they are necessary. This thesis contributes to the development of a different positioning approach, which is fully relativistic from the beginning. In the relativistic positioning systems (RPS), the space-time position of any user (ship, spacecraft, and so on) can be calculated with the help of four satellites, which broadcast their proper times by means of codified electromagnetic signals. In this thesis, we have simulated satellite 4-tuples of the GPS and GALILEO constellations. If a user receives the signals from four satellites simultaneously, the emission proper times read -after decoding- are the user "emission coordinates". In order to find the user "positioning coordinates", in an appropriate almost inertial reference system, there are two possibilities: (a) the explicit relation between positioning and emission coordinates (broadcast by the satellites) is analytically found or (b) numerical codes are designed to calculate the positioning coordinates from the emission ones. Method (a) is only viable in simple ideal cases, whereas (b) allows us to consider realistic situations. In this thesis, we have designed numerical codes with the essential aim of studying two appropriate RPS, which may be generalized. Sometimes, there are two real users placed in different positions, which receive the same proper times from the same satellites; then, we say that there is bifurcation, and additional data are needed to choose the real user position. In this thesis, bifurcation is studied in detail. We have analyzed in depth two RPS models; in both, it is considered that the satellites move in the Schwarzschild's space
International Nuclear Information System (INIS)
Toti, A.; Vierendeels, J.; Belloni, F.
2017-01-01
Highlights: • A system thermal-hydraulic/CFD coupling methodology is proposed for high-fidelity transient flow analyses. • The method is based on domain decomposition and implicit numerical scheme. • A novel interface Quasi-Newton algorithm is implemented to improve stability and convergence rate. • Preliminary validation analyses on the TALL-3D experiment. - Abstract: The paper describes the development and validation of a coupling methodology between the best-estimate system thermal-hydraulic code RELAP5-3D and the CFD code FLUENT, conceived for high fidelity plant-scale safety analyses of pool-type reactors. The computational tool is developed to assess the impact of three-dimensional phenomena occurring in accidental transients such as loss of flow (LOF) in the research reactor MYRRHA, currently in the design phase at the Belgian Nuclear Research Centre, SCK• CEN. A partitioned, implicit domain decomposition coupling algorithm is implemented, in which the coupled domains exchange thermal-hydraulics variables at coupling boundary interfaces. Numerical stability and interface convergence rates are improved by a novel interface Quasi-Newton algorithm, which is compared in this paper with previously tested numerical schemes. The developed computational method has been assessed for validation purposes against the experiment performed at the test facility TALL-3D, operated by the Royal Institute of Technology (KTH) in Sweden. This paper details the results of the simulation of a loss of forced convection test, showing the capability of the developed methodology to predict transients influenced by local three-dimensional phenomena.
International Nuclear Information System (INIS)
Sakamoto, Kazuaki; Hattori, Yasuo; Koga, Tomonari; Wataru, Masumi
1999-01-01
On the basis of the result of the heat removal test on vault storage system of cross flow type using the 1/5 scale model, an evaluation method for the heat removal design was established. It was composed of the numerical analysis for the convection phenomena of air flow inside the whole facility and that for the natural convection and the detailed turbulent mechanism near the surface of the storage tube. In the former analysis, air temperature distribution in the storage area obtained by the calculation gave good agreement within ±3degC with the test result. And fine turbulence models were introduced in the latter analysis to predict the separation flow in the boundary layer near the surface of the storage tube and the buoyant flow generated by the heat from the storage tube. Furthermore, the properties of removing the heat in a designed full-scale storage facility, such as flow pattern in the storage area, temperature and heat transfer rate of the storage tubes, were evaluated by using each of three methods, which were the established numerical analysis method, the experimental formula demonstrated in the heat removal test and the conventional evaluation method applied to the past heat removal design. As a result, the safety margin and issues included in the methods were grasped, and the measures to make a design more rational were proposed. (author)
Strongly correlated systems numerical methods
Mancini, Ferdinando
2013-01-01
This volume presents, for the very first time, an exhaustive collection of those modern numerical methods specifically tailored for the analysis of Strongly Correlated Systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and material science, belong to this class of systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognized main contributors. The exposition has a clear pedagogical cut and fully reports on the most relevant case study where the specific technique showed to be very successful in describing and enlightening the puzzling physics of a particular strongly correlated system. The book is intended for advanced graduate students and post-docs in the field as textbook and/or main reference, but also for other researchers in the field who appreciate consulting a single, but comprehensive, source or wishes to get acquainted, in a as painless as possi...
Directory of Open Access Journals (Sweden)
Abu-Bakre Abdelmoneim Elamin Mohamad
2016-08-01
Full Text Available The developed study aimed at investigating the mechanical behavior of a new type of self-insulating concrete masonry unit (SCMU. A total of 12 full-grouted wall assemblages were prepared and tested for compression and shear strength. In addition, different axial stress ratios were used in shear tests. Furthermore, numerical models were developed to predict the behavior of grouted specimens using simplified micro-modeling technique. The mortar joints were modeled with zero thickness and their behavior was applied using the traction–separation model of the cohesive element. The experimental results revealed that the shear resistance increases as the level of precompression increases. A good agreement between the experimental results and numerical models was observed. It was concluded that the proposed models can be used to deduct the general behavior of grouted specimens.
Interagency mechanical operations group numerical systems group
Energy Technology Data Exchange (ETDEWEB)
NONE
1997-09-01
This report consists of the minutes of the May 20-21, 1971 meeting of the Interagency Mechanical Operations Group (IMOG) Numerical Systems Group. This group looks at issues related to numerical control in the machining industry. Items discussed related to the use of CAD and CAM, EIA standards, data links, and numerical control.
Analytical and numerical tools for vacuum systems
Kersevan, R
2007-01-01
Modern particle accelerators have reached a level of sophistication which require a thorough analysis of all their sub-systems. Among the latter, the vacuum system is often a major contributor to the operating performance of a particle accelerator. The vacuum engineer has nowadays a large choice of computational schemes and tools for the correct analysis, design, and engineering of the vacuum system. This paper is a review of the different type of algorithms and methodologies which have been developed and employed in the field since the birth of vacuum technology. The different level of detail between simple back-of-the-envelope calculations and more complex numerical analysis is discussed by means of comparisons. The domain of applicability of each method is discussed, together with its pros and cons.
Numerical Modeling of Microelectrochemical Systems
DEFF Research Database (Denmark)
Adesokan, Bolaji James
incorporates the finite size of ionic species in the transport equation. The model presents a more appropriate boundary conditions which describe the modified Butler-Volmer reaction kinetics and account for the surface capacitance of the thin electric double layer. We also have found analytical solution...... at the electrode in a microelectrochemical system. In our analysis, we account for the finite size properties of ions in the mass and the charge transport of ionic species in an electrochemical system. This term characterizes the saturation of the ionic species close to the electrode surface. We then analyse......The PhD dissertation is concerned with mathematical modeling and simulation of electrochemical systems. The first three chapters of the thesis consist of the introductory part, the model development chapter and the chapter on the summary of the main results. The remaining three chapters report...
DEFF Research Database (Denmark)
Elsborg, Ebbe; Hildebrandt, Thomas; Sangiorgi, Davide
of controls and a set of reaction rules, collectively a bigraphical reactive system (BRS). Possible advantages of developing bigraphical type systems include: a deeper understanding of a type system itself and its properties; transfer of the type systems to the concrete family of calculi that the BRS models...
Numerical algorithms for uniform Airy-type asymptotic expansions
N.M. Temme (Nico)
1997-01-01
textabstractAiry-type asymptotic representations of a class of special functions are considered from a numerical point of view. It is well known that the evaluation of the coefficients of the asymptotic series near the transition point is a difficult problem. We discuss two methods for computing
Numerical solution of large sparse linear systems
International Nuclear Information System (INIS)
Meurant, Gerard; Golub, Gene.
1982-02-01
This note is based on one of the lectures given at the 1980 CEA-EDF-INRIA Numerical Analysis Summer School whose aim is the study of large sparse linear systems. The main topics are solving least squares problems by orthogonal transformation, fast Poisson solvers and solution of sparse linear system by iterative methods with a special emphasis on preconditioned conjuguate gradient method [fr
An integrated numerical protection system (SPIN)
International Nuclear Information System (INIS)
Savornin, J.L.; Bouchet, J.M.; Furet, J.L.; Jover, P.; Sala, A.
1978-01-01
Developments in technology have now made it possible to perform more sophisticated protection functions which follow more closely the physical phenomena to be monitored. For this reason the Commissariat a l'energie atomique, Merlin-Gerin, Cerci and Framatome have embarked on the joint development of an Integrated Numerical Protection System (SPIN) which will fulfil this objective and will improve the safety and availability of power stations. The system described involves the use of programmed numerical techniques and a structure based on multiprocessors. The architecture has a redundancy of four. Throughout the development of the project the validity of the studies was confirmed by experiments. A first numerical model of a protection function was tested in the laboratory and is now in operation in a power station. A set of models was then introduced for checking the main components of the equipment finally chosen prior to building and testing a prototype. (author)
Research on ARM Numerical Control System
Wei, Xu; JiHong, Chen
Computerized Numerical Control (CNC) machine tools is the foundation of modern manufacturing systems, whose advanced digital technology is the key to solve the problem of sustainable development of machine tool manufacturing industry. The paper is to design CNC system embedded on ARM and indicates the hardware design and the software systems supported. On the hardware side: the driving chip of the motor control unit, as the core of components, is MCX314AL of DSP motion control which is developed by NOVA Electronics Co., Ltd. of Japan. It make convenient to control machine because of its excellent performance, simple interface, easy programming. On the Software side, the uC/OS-2 is selected as the embedded operating system of the open source, which makes a detailed breakdown of the modules of the CNC system. Those priorities are designed according to their actual requirements. The ways of communication between the module and the interrupt response are so different that it guarantees real-time property and reliability of the numerical control system. Therefore, it not only meets the requirements of the current social precision machining, but has good man-machine interface and network support to facilitate a variety of craftsmen use.
Children, algorithm and the decimal numeral system
Directory of Open Access Journals (Sweden)
Clélia Maria Ignatius Nogueira
2010-08-01
Full Text Available A large number of studies in Mathematics Education approach some possible problems in the study of algorithms in the early school years of arithmetic teaching. However, this discussion is not exhausted. In this feature, this article presents the results of a research which proposed to investigate if the arithmetic’s teaching, with emphasis in the fundamental operation’s algorithm, cooperate to build the mathematics knowledge, specifically of the Decimal Numeral System. In order to achieve this purpose, we interviewed, using the Piaget Critique Clinical Method, twenty students from a public school. The result’s analysis indicates that they mechanically reproduce the regular algorithm’s techniques without notice the relations between the techniques and the principle and the Decimal Numeral System’s properties.
Numerical solution of the polymer system
Energy Technology Data Exchange (ETDEWEB)
Haugse, V.; Karlsen, K.H.; Lie, K.-A.; Natvig, J.R.
1999-05-01
The paper describes the application of front tracking to the polymer system, an example of a nonstrictly hyperbolic system. Front tracking computes piecewise constant approximations based on approximate Remain solutions and exact tracking of waves. It is well known that the front tracking method may introduce a blow-up of the initial total variation for initial data along the curve where the two eigenvalues of the hyperbolic system are identical. It is demonstrated by numerical examples that the method converges to the correct solution after a finite time that decreases with the discretization parameter. For multidimensional problems, front tracking is combined with dimensional splitting and numerical experiments indicate that large splitting steps can be used without loss of accuracy. Typical CFL numbers are in the range of 10 to 20 and comparisons with the Riemann free, high-resolution method confirm the high efficiency of front tracking. The polymer system, coupled with an elliptic pressure equation, models two-phase, tree-component polymer flooding in an oil reservoir. Two examples are presented where this model is solved by a sequential time stepping procedure. Because of the approximate Riemann solver, the method is non-conservative and CFL members must be chosen only moderately larger than unity to avoid substantial material balance errors generated in near-well regions after water breakthrough. Moreover, it is demonstrated that dimensional splitting may introduce severe grid orientation effects for unstable displacements that are accentuated for decreasing discretization parameters. 9 figs., 2 tabs., 26 refs.
Numerical analysis on centrifugal compressor with membrane type dryer
Razali, M. A.; Zulkafli, M. F.; Mat Isa, N.; Subari, Z.
2017-09-01
Moisture content is a common phenomenon in industrial processes especially in oil and gas industries. This contaminant has a lot of disadvantages which can lead to mechanical failure DEC (Deposition, Erosion & Corrosion) problems. To overcome DEC problem, this study proposed to design a centrifugal compressor with a membrane type dryer to reduce moisture content of a gas. The effectiveness of such design has been analyzed in this study using Computational Fluid Dynamics (CFD) approach. Numerical scheme based on multiphase flow technique is used in ANSYS Fluent software to evaluate the moisture content of the gas. Through this technique, two kind of centrifugal compressor, with and without membrane type dryer has been tested. The results show that the effects of pressure on dew point temperature of the gas change the composition of its moisture content, where high value lead more condensation to occur. However, with the injection of cool dry gas through membrane type dryer in the centrifugal compressor, the pressure and temperature of moisture content as well as mass fraction of H2O in centrifugal compressor show significant reduction.
Numeral-Incorporating Roots in Numeral Systems: A Comparative Analysis of Two Sign Languages
Fuentes, Mariana; Massone, Maria Ignacia; Fernandez-Viader, Maria del Pilar; Makotrinsky, Alejandro; Pulgarin, Francisca
2010-01-01
Numeral-incorporating roots in the numeral systems of Argentine Sign Language (LSA) and Catalan Sign Language (LSC), as well as the main features of the number systems of both languages, are described and compared. Informants discussed the use of numerals and roots in both languages (in most cases in natural contexts). Ten informants took part in…
Salomon, Dor; Orth, Kim
2015-03-30
Bacteria employ a variety of tools to survive in a competitive environment. Salomon and Orth describe one such tool-the Type 6 Secretion Systems used by bacteria to deliver a variety of toxins into competing cells. Copyright © 2015 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Hu, Q; Li, Y; Pan, H L; Liu, J T; Zhuang, B T
2015-01-01
Vane type propellant management device (PMD) is one of the key components of the vane-type surface tension tank (STT), and its fluid orbital performance directly determines the STT's success or failure. In present paper, numerical analysis and microgravity experiment study on fluid orbital performance of a vane type PMD were carried out. By using two-phase flow model of volume of fluid (VOF), fluid flow characteristics in the tank with the vane type PMD were numerically calculated, and the rules of fluid transfer and distribution were gotten. A abbreviate model test system of the vane type PMD is established and microgravity drop tower tests were performed, then fluid management and transmission rules of the vane type PMD were obtained under microgravity environment. The analysis and tests results show that the vane type PMD has good and initiative fluid orbital management ability and meets the demands of fluid orbital extrusion in the vane type STT. The results offer valuable guidance for the design and optimization of the new generation of vane type PMD, and also provide a new approach for fluid management and control in space environment
Biofouling in forward osmosis systems: An experimental and numerical study
Bucs, Szilard; Valladares Linares, Rodrigo; Vrouwenvelder, Johannes S.; Picioreanu, Cristian
2016-01-01
This study evaluates with numerical simulations supported by experimental data the impact of biofouling on membrane performance in a cross-flow forward osmosis (FO) system. The two-dimensional numerical model couples liquid flow with solute
Directory of Open Access Journals (Sweden)
M. Boumaza
2015-07-01
Full Text Available Transient convection heat transfer is of fundamental interest in many industrial and environmental situations, as well as in electronic devices and security of energy systems. Transient fluid flow problems are among the more difficult to analyze and yet are very often encountered in modern day technology. The main objective of this research project is to carry out a theoretical and numerical analysis of transient convective heat transfer in vertical flows, when the thermal field is due to different kinds of variation, in time and space of some boundary conditions, such as wall temperature or wall heat flux. This is achieved by the development of a mathematical model and its resolution by suitable numerical methods, as well as performing various sensitivity analyses. These objectives are achieved through a theoretical investigation of the effects of wall and fluid axial conduction, physical properties and heat capacity of the pipe wall on the transient downward mixed convection in a circular duct experiencing a sudden change in the applied heat flux on the outside surface of a central zone.
Large quantum systems: a mathematical and numerical perspective
International Nuclear Information System (INIS)
Lewin, M.
2009-06-01
This thesis is devoted to the mathematical study of variational models for large quantum systems. The mathematical methods are that of nonlinear analysis, calculus of variations, partial differential equations, spectral theory, and numerical analysis. The first part contains some results on finite systems. We study several approximations of the N-body Schroedinger equation for electrons in an atom or a molecule, and then the so-called Hartree-Fock- Bogoliubov model for a system of fermions interacting via the gravitational force. In a second part, we propose a new method allowing to prove the existence of the thermodynamic limit of Coulomb quantum systems. Then, we construct two Hartree-Fock-type models for infinite systems. The first is a relativistic theory deduced from Quantum Electrodynamics, allowing to describe the behavior of electrons, coupled to that of Dirac's vacuum which can become polarized. The second model describes a nonrelativistic quantum crystal in the presence of a charged defect. A new numerical method is also proposed. The last part of the thesis is devoted to spectral pollution, a phenomenon which is observed when trying to approximate eigenvalues in a gap of the essential spectrum of a self-adjoint operator, for instance for periodic Schroedinger operators or Dirac operators. (author)
Institute of Scientific and Technical Information of China (English)
李争; 高培峰; 孙甜甜; 薛增涛; 王群京
2017-01-01
研究了一种小型分布式能源系统用阻力型垂直轴风机(VAWT)的特性,在原有风机基础上,将风轮增加为两层.基于流体动力学(CFD)对风机性能进行计算,依据空气动力学原理,模拟风轮与空气的流固耦合作用,分析流场风速分布以及风机在不同旋转角度下的综合受力情况,根据转矩特性,在Matlab中建立风轮的数学模型,然后使用最大功率跟踪控制方法,建立风机发电系统的数学模型,从而仿真得到发电机的电压、电流等发电特性曲线.最后,与实测数据进行对比,验证了数值仿真和分析的正确性,为今后该类风机结构优化设计和效率提升提供了借鉴和参考.%The properties of the drag type vertical axis wind turbine (VAWT) for small distributed energy systems have been investigated.Based on the original turbine structure, the turbine rotor is increased to two layers.The characteristics are calculated by Computational Fluid Dynamics (CFD) software, according to the aerodynamic principles, the fluid-solid coupling effects of turbine and air flow are simulated, the distribution of wind velocity in the flow field and the integrated force of the turbine at different rotation angles are analyzed, according to the torque characteristics, the mathematical model of the wind turbine is established in Matlab, then the mathematical model of the wind turbine power generation system is established by using the method of maximum power tracking control, and the voltage, current and other power generation curves of the generator can be calculated;Finally, compared with the measured data, the correctness of numerical simulation and analysis is verified.The results provide the guide and reference for further turbine structure optimization and efficiency improvement of same kind of wind turbines.
DEFF Research Database (Denmark)
Schwartzbach, Michael Ignatieff; Palsberg, Jens
binding. Existing languages employ different type systems, and it can be difficult to compare, evaluate and improve them, since there is currently no uniform theory for such languages. This book provides such a theory. The authors review the type systems of Simula, Smalltalk, C++ and Eiffel and present......Object-Oriented Type Systems Jens Palsberg and Michael I. Schwartzbach Aarhus University, Denmark Type systems are required to ensure reliability and efficiency of software. For object-oriented languages, typing is an especially challenging problem because of inheritance, assignment, and late...... a type system that generalizes and explains them. The theory is based on an idealized object-oriented language called BOPL (Basic Object Programming Language), containing common features of the above languages. A type system, type inference algorithm, and typings of inheritance and genericity...
Parameters in pure type systems
Bloo, C.J.; Kamareddine, F.; Laan, T.D.L.; Nederpelt, R.P.; Rajsbaum, S.
2002-01-01
In this paper we study the addition of parameters to typed ¿-calculus with definitions. We show that the resulting systems have nice properties and illustrate that parameters allow for a better fine-tuning of the strength of type systems as well as staying closer to type systems used in practice in
Numerical Investigation of Floor Heating Systems in Low Energy Houses
DEFF Research Database (Denmark)
Weitzmann, Peter; Kragh, Jesper; Jensen, Claus Franceos
2002-01-01
In this paper an investigation of floor heating systems is performed with respect to heating demand and room temperature. Presently (2001) no commercially available building simulation programs that can be used to evaluate heating demand and thermal comfort in buildings with building integrated....... The model calculates heating demand, room temperatures, and thermal comfort parameters for a person in the room. The model is based on a numerical Finite Control Volume (FCV) method for the heat transfer in walls, ceiling, windows and floor. The model uses both convective and radiative heat transfer...... to the room air and between the room surfaces. The simulation model has been used to calculate heating demand and room temperature in a typical well insulated Danish single-family house with a heating demand of approximately 6000 kWh per year, for a 130 m² house. Two different types of floor heating systems...
Electric field numerical simulation of disc type electrostatic spinning spinneret
Wei, L.; Deng, ZL; Qin, XH; Liang, ZY
2018-01-01
Electrospinning is a new type of free-end spinning built on electric field. Different from traditional single needle spinneret, in this study, a new disc type free surface spinneret is used to produce multiple jets, this will greatly improve production efficiency of nanofiber. The electric-field distribution of spinneret is the crux of the formation and trajectory of jets. In order to probe the electric field intensity of the disc type spinneret, computational software of Ansoft Maxwell 12 is adopted for a precise and intuitive analysis. The results showed that the whole round cambered surface of the spinning solution at edge of each layer of the spinneret with the maximum curvature has the highest electric field intensity, and through the simulation of the electric field distribution of different spinneret parameters such as layer, the height and radius of the spinneret. Influences of various parameters on the electrostatic spinning are obtained.
Numerical simulation research on gas migration with Y type ventilation
Gou, Yanan; Han, Xuezheng
2018-01-01
The ventilation way of the working face has a great influence to goaf flow field and gas migration, the existing U-shaped ventilation face wind serious overrun, Y type ventilation mode is put forward, and the mathematic control equation of the gas moving rule is established. Put the Gaozhuang coal mine west five mining area as the model, set up calculation model. And the gas concentration is simulated, the simulation results show that the Y type ventilation ways can intercept goaf gas into the corner on the working plane and return air lane, effectively avoid the work of top corner gas accumulation.
DEFF Research Database (Denmark)
Schwartzbach, Michael Ignatieff; Palsberg, Jens
a type system that generalizes and explains them. The theory is based on an idealized object-oriented language called BOPL (Basic Object Programming Language), containing common features of the above languages. A type system, type inference algorithm, and typings of inheritance and genericity......Object-Oriented Type Systems Jens Palsberg and Michael I. Schwartzbach Aarhus University, Denmark Type systems are required to ensure reliability and efficiency of software. For object-oriented languages, typing is an especially challenging problem because of inheritance, assignment, and late...... are provided for BOPL. Throughout, the results are related to the languages on which BOPL is based. This text offers advanced undergraduates and professional software developers a sound understanding of the key aspects of object-oriented type systems. All algorithms are implemented in a freely available...
A parallel architecture system dedicated to fast numerical calculus
International Nuclear Information System (INIS)
Harmanci, A.E.
1982-04-01
The project described here is the first result of a careful reflection oriented to the implementation of a machine intended for fast scientific computation, having in mind applications in the field of nuclear reactor safety. The selected structure is a data processing system of the MIMD type (Multiple Instruction, Multiple Data Stream). It is built by generalizing a basic cell constituted by associating an host processor and one or several processors dedicated to numerical computation, both operating alternatively on two areas of a common memory block. The principle of simultaneous operation of a large number of identical resources is used at every level of the structure. The system described here is hence modular and reconfigurable. The number of cells, the size and number of memory blocks may be chosen according to the needs. The communication between processors is carried out through the switching of the allocation of memory blocks. Moreover the numerical processors make the best use of private interconnections for synchronisation and fast data interchange. The present study devoted to the definition of the main hardware structures, will be followed by a simulation phase while suitable software tools will be developed [fr
Computable Types for Dynamic Systems
P.J. Collins (Pieter); K. Ambos-Spies; B. Loewe; W. Merkle
2009-01-01
textabstractIn this paper, we develop a theory of computable types suitable for the study of dynamic systems in discrete and continuous time. The theory uses type-two effectivity as the underlying computational model, but we quickly develop a type system which can be manipulated abstractly, but for
Pure type systems with subtyping
Zwanenburg, J.; Girard, J.-Y.
1999-01-01
We extend the framework of Pure Type Systems with subtyping, as found in F = ¿ . This leads to a concise description of many existing systems with subtyping, and also to some new interesting systems. We develop the meta-theory for this framework, including Subject Reduction and Minimal Typing. The
Operating System For Numerically Controlled Milling Machine
Ray, R. B.
1992-01-01
OPMILL program is operating system for Kearney and Trecker milling machine providing fast easy way to program manufacture of machine parts with IBM-compatible personal computer. Gives machinist "equation plotter" feature, which plots equations that define movements and converts equations to milling-machine-controlling program moving cutter along defined path. System includes tool-manager software handling up to 25 tools and automatically adjusts to account for each tool. Developed on IBM PS/2 computer running DOS 3.3 with 1 MB of random-access memory.
NUMERICAL ANALYSIS OF A CHAOTIC SYSTEM
Institute of Scientific and Technical Information of China (English)
任志坚
2001-01-01
This paper further proves that a single spiral strange attractor can be observed in an extremely simple autonomous electrical circuit by computer simulation. It is of third order and has only one nonlinear element: a three-segment piecewise linear resistor. The digital analyses show that the strange attractor has peculiar features compared with other third-order differential systems.
Numerical analysis of a waterjet propulsion system
Bulten, N.W.H.
2006-01-01
A waterjet propulsion system is used to propel ships, using a pump which produces a high speed jet. A standard waterjet installation can be divided into an inlet, a pump and a nozzle. For manoeuvring and reversing purposes an additional steering device can be integrated into the installation. The
Numerical Study on the Cooling Characteristics of a Passive-Type PEMFC Stack
International Nuclear Information System (INIS)
Lee, Jae Hyuk; Kim, Bo Sung; Lee, Yong Taek; Kim, Yong Chan
2010-01-01
In a passive-type PEMFC stack, axial fans operate to supply both oxidant and coolant to cathode side of the stack. It is possible to make a simple system because the passive-type PEMFC stack does not require additional cooling equipment. However, the performance of a cooling system in which water is used as a coolant is better than that of the air-cooling system. To ensure system reliability, it is essential to make cooling system effective by adopting an optimal stack design. In this study, a numerical investigation has been carried out to identify an optimum cooling strategy. Various channel configurations were applied to the test section. The passive-type PEMFC was tested by varying airflow rate distribution at the cathode side and external heat transfer coefficient of the stack. The best cooling performance was achieved when a channel with thick ribs was used, and the overheating at the center of the stack was reduced when a case in which airflow was concentrated at the middle of the stack was used
Generalized Database Management System Support for Numeric Database Environments.
Dominick, Wayne D.; Weathers, Peggy G.
1982-01-01
This overview of potential for utilizing database management systems (DBMS) within numeric database environments highlights: (1) major features, functions, and characteristics of DBMS; (2) applicability to numeric database environment needs and user needs; (3) current applications of DBMS technology; and (4) research-oriented and…
Numerical quantification of habitability in serpentinizing systems
Som, S.; Alperin, M. J.; Hoehler, T. M.
2012-12-01
The likely presence of liquid water in contact with olivine-bearing rocks on Mars, the detection of serpentine minerals and of methane emissions possibly consistent with serpentinization, and the observation of serpentine-associated methane-cycling communities on Earth have all led to excitement over the potential of such systems to host life on Mars, even into the present day. However, the habitability of subsurface serpentinizing systems on Mars does not necessarily follow from these qualitative observations. In particular, while the production of H2 during serpentinization could provide methanogens with a needed substrate, the alkaline conditions and corresponding potential for carbon limitation that arise in concert are negatives against which H2 supply must be balanced. We considered this balance via a coupled geochemical-bioenergetic model that weighs the outputs of serpentinization against the metabolic requirements of methanogenesis, in an energetic frame of reference. Serpentinization is modeled using the "Geochemist's Workbench" (GWB) whereby ultramafic harzburgite rocks are reacted with oxygen and sulfate depleted seawater. Reaction kinetics are not explicitly considered, but comparable effects of partial reaction are approximated by assuming post-reaction dilution of equilibrated fluids. The output of GWB serves as the input to the bioenergetic model, which calculates methanogenic energy yields based on spherically-symmetrical diffusion of substrates to a cell followed by reaction at the diffusion-limited rate. Membrane selectivity for substrate transport is explicitly considered. Results will be report updates for two scenarios: (i) High temperature serpentinization followed by cooling and transport of equilibrated fluid to a lower temperature regime accessible to biology; (ii) Serpentinization within the biologically-tolerated range of temperatures. Such coupled models demonstrate that environmental variability with respect to both water-rock reaction
Numerical modeling of underground storage system for natural gas
Ding, J.; Wang, S.
2017-12-01
Natural gas is an important type of base-load energy, and its supply needs to be adjusted according to different demands in different seasons. For example, since natural gas is increasingly used to replace coal for winter heating, the demand for natural gas in winter is much higher than that in other seasons. As storage systems are the essential tools for balancing seasonal supply and demand, the design and simulation of natural gas storage systems form an important research direction. In this study, a large-scale underground storage system for natural gas is simulated based on theoretical analysis and finite element modeling.It is proven that the problem of axi-symmetric Darcy porous flow of ideal gas is governed by the Boussinesq equation. In terms of the exact solution to the Boussinesq equation, the basic operating characteristics of the underground storage system is analyzed, and it is demonstrated that the propagation distance of the pore pressure is proportional to the 1/4 power of the mass flow rate and to the 1/2 power of the propagation time. This quantitative relationship can be used to guide the overall design of natural gas underground storage systems.In order to fully capture the two-way coupling between pore pressure and elastic matrix deformation, a poro-elastic finite element model for natural gas storage is developed. Based on the numerical model, the dynamic processes of gas injection, storage and extraction are simulated, and the corresponding time-dependent surface deformations are obtained. The modeling results not only provide a theoretical basis for real-time monitoring for the operating status of the underground storage system through surface deformation measurements, but also demonstrate that a year-round balance can be achieved through periodic gas injection and extraction.This work is supported by the CAS "100 talents" Program and the National Natural Science Foundation of China (41371090).
Intersection Types and Related Systems
Directory of Open Access Journals (Sweden)
Paweł Parys
2017-02-01
Full Text Available We present a new approach to the following meta-problem: given a quantitative property of trees, design a type system such that the desired property for the tree generated by an infinitary ground lambda-term corresponds to some property of a derivation of a type for this lambda-term, in this type system. Our approach is presented in the particular case of the language finiteness problem for nondeterministic higher-order recursion schemes (HORSes: given a nondeterministic HORS, decide whether the set of all finite trees generated by this HORS is finite. We give a type system such that the HORS can generate a tree of an arbitrarily large finite size if and only if in the type system we can obtain derivations that are arbitrarily large, in an appropriate sense; the latter condition can be easily decided.
International Nuclear Information System (INIS)
Hayashi, Kenji; Kawamata, Nobuhiro; Kamide, Hideki
2003-03-01
In a fast reactor an Inter-Wrapper Flow (IWF) is one of significant phenomena for decay heat removal under natural circulation condition, when a direct reactor auxiliary cooling system (DRACS) is adopted for decay heat removal system. Cold coolant provided by dipped heat exchangers (DHX) of DRACS can penetrate into the core barrel (region between the subassemblies) and it makes natural convection int he core barrel. Such IWF will depend on a spacer pad geometry of subassemblies. Water experiment, TRIF (Test Rig for Inter-wrapper Flow), was carried out for IWF in a reactor core. The test section modeled a 1/12th sector of the core and upper plenum of reactor vessel. Experimental parameters were the spacer pad geometry and flow path geometries connecting the upper plenum and core barrel. Numerical simulation using AQUA code was also performed to confirm applicability of a simulation method. An experimental series using a button type spacer pad had been carried out. Here a band type spacer pad was examined. Temperatures at subassembly wall were measured with parameter of the flow path geometries; one was a connection pipe between the upper plenum and core barrel and the other was flow hole in core former plates between the outermost subassemblies and the core barrel. It was found that these flow paths were effective to remove heat in the core in case of the band type spacer pad. A general purpose three dimensional analysis code, AQUA, was applied to the experimental analysis. Each subassembly and inter wrapper gap region were modeled by slab mesh geometry. Pressure loss coefficient at the pacer pad was set based on the geometry. The numerical simulation results were in good agreement with measured temperature profiles in the core. (author)
Numerical Analysis of Impulse Turbine for Isolated Pilot OWC System
Directory of Open Access Journals (Sweden)
Zhen Liu
2013-01-01
Full Text Available Oscillating water column (OWC is the most widely used wave energy converting technology in the world. The impulse turbine is recently been employed as the radial turbine in OWC facilities to convert bidirectional mechanical air power into electricity power. 3D numerical model for the impulse turbine is established in this paper to investigate its operating performance of the designed impulse turbine for the pilot OWC system which is under the construction on Jeju Island, Republic of Korea. The proper mesh style, turbulence model, and numerical solutions are employed to study the velocity and air pressure distribution especially around the rotor blade. The operating coefficients obtained from the numerical simulation are compared with corresponding experimental data, which demonstrates that the 3D numerical model proposed here can be applied to the research of impulse turbines for OWC system. Effects of tip clearances on flow field distribution characteristics and operating performances are also studied.
Mechanical Interaction in Pressurized Pipe Systems: Experiments and Numerical Models
Directory of Open Access Journals (Sweden)
Mariana Simão
2015-11-01
Full Text Available The dynamic interaction between the unsteady flow occurrence and the resulting vibration of the pipe are analyzed based on experiments and numerical models. Waterhammer, structural dynamic and fluid–structure interaction (FSI are the main subjects dealt with in this study. Firstly, a 1D model is developed based on the method of characteristics (MOC using specific damping coefficients for initial components associated with rheological pipe material behavior, structural and fluid deformation, and type of anchored structural supports. Secondly a 3D coupled complex model based on Computational Fluid Dynamics (CFD, using a Finite Element Method (FEM, is also applied to predict and distinguish the FSI events. Herein, a specific hydrodynamic model of viscosity to replicate the operation of a valve was also developed to minimize the number of mesh elements and the complexity of the system. The importance of integrated analysis of fluid–structure interaction, especially in non-rigidity anchored pipe systems, is equally emphasized. The developed models are validated through experimental tests.
Two systems of non-symbolic numerical cognition
Directory of Open Access Journals (Sweden)
Daniel C. Hyde
2011-11-01
Full Text Available Studies of human adults, infants, and non-human animals demonstrate that non-symbolic numerical cognition is supported by at least two distinct cognitive systems: a ‘parallel individuation system’ that encodes the numerical identity of individual items and an ‘approximate number system’ that encodes the approximate numerical magnitude, or numerosity, of a set. The exact nature of these systems, however, have been debated for over a hundred years. Some argue that the non-symbolic representation of small numbers (< 4 is carried out solely by the parallel individuation system and the non-symbolic representation of large numbers (> 4 is carried out solely by the approximate number system. Others argue that all numbers are represented by the approximate number system. This debate has been fueled largely by some studies showing dissociations in processing and other studies showing similar processing of small and large numbers. Recent work has addressed this debate by showing that the two systems are present and distinct from early infancy, persist despite the acquisition of a symbolic number system, activate distinct cortical networks, and engage differentially based attentional constraints. Based on the recent discoveries, I provide a hypothesis that may explain the puzzling findings and makes testable predictions as to when each system will be engaged. In particular, when items are presented under conditions that allow selection of individuals, they will be represented as distinct mental items through parallel individuation and not as a numerical magnitude. In contrast, when items are presented outside attentional limits (e.g. too many, too close together, under high attentional load, they will be represented as a single mental numerical magnitude and not as distinct mental items. These predictions provide a basis on which researchers can further investigate the role of each system in the development of uniquely human numerical thought.
Directory of Open Access Journals (Sweden)
Claude Kirchner
2010-03-01
Full Text Available Extending a given language with new dedicated features is a general and quite used approach to make the programming language more adapted to problems. Being closer to the application, this leads to less programming flaws and easier maintenance. But of course one would still like to perform program analysis on these kinds of extended languages, in particular type checking and inference. In this case one has to make the typing of the extended features compatible with the ones in the starting language. The Tom programming language is a typical example of such a situation as it consists of an extension of Java that adds pattern matching, more particularly associative pattern matching, and reduction strategies. This paper presents a type system with subtyping for Tom, that is compatible with Java's type system, and that performs both type checking and type inference. We propose an algorithm that checks if all patterns of a Tom program are well-typed. In addition, we propose an algorithm based on equality and subtyping constraints that infers types of variables occurring in a pattern. Both algorithms are exemplified and the proposed type system is showed to be sound and complete.
One-dimensional numerical simulation of the Stirling-type pulse-tube refrigerator
Etaati, M.; Mattheij, R.M.M.; Tijsseling, A.S.; Waele, de A.T.A.M.
2007-01-01
Change of title: One-dimensional numerical simulation of the Stirling-type pulse-tube cooler. Pulse-tube refrigeration (PTR) is a new technology for cooling down to extremely low temperatures. In this paper a particular type, the so-called Stirling single-stage refrigerator, is considered. A
International Nuclear Information System (INIS)
Jeong, Jong Yun; Kang, Yong Tae; Nam, Sang Chul
2008-01-01
Numerical analysis was carried out to examine the heat transfer and pressure drop characteristics of plate heat exchangers for absorption application using computational Fluid Dynamics(CFD) technique. A commercial CFD software package, FLUENT was used to predict the characteristics of heat transfer, pressure drop and flow distribution within plate heat exchangers. In this paper, a welded plate heat exchanger with the plate of chevron embossing type was numerically analyzed by controlling mass flow rate, solution concentration, and inlet temperatures. The working fluid is H 2 O/LiBr solution with the LiBr concentration of 50∼60% in mass. The numerical simulation show reasonably good agreement with the experimental results. Also, the numerical results show that plate of the chevron shape gives better results than plate of the elliptical shape from the view points of heat transfer and pressure drop. These results provide a guideline to apply the welded PHE for the solution heat exchanger of absorption systems
Microwave Breast Imaging System Prototype with Integrated Numerical Characterization
Directory of Open Access Journals (Sweden)
Mark Haynes
2012-01-01
Full Text Available The increasing number of experimental microwave breast imaging systems and the need to properly model them have motivated our development of an integrated numerical characterization technique. We use Ansoft HFSS and a formalism we developed previously to numerically characterize an S-parameter- based breast imaging system and link it to an inverse scattering algorithm. We show successful reconstructions of simple test objects using synthetic and experimental data. We demonstrate the sensitivity of image reconstructions to knowledge of the background dielectric properties and show the limits of the current model.
Chen, Xinzhong; Lo, Chiu Fan Bowen; Zheng, William; Hu, Hai; Dai, Qing; Liu, Mengkun
2017-11-01
Over the last decade, scattering-type scanning near-field optical microscopy and spectroscopy have been widely used in nano-photonics and material research due to their fine spatial resolution and broad spectral range. A number of simplified analytical models have been proposed to quantitatively understand the tip-scattered near-field signal. However, a rigorous interpretation of the experimental results is still lacking at this stage. Numerical modelings, on the other hand, are mostly done by simulating the local electric field slightly above the sample surface, which only qualitatively represents the near-field signal rendered by the tip-sample interaction. In this work, we performed a more comprehensive numerical simulation which is based on realistic experimental parameters and signal extraction procedures. By directly comparing to the experiments as well as other simulation efforts, our methods offer a more accurate quantitative description of the near-field signal, paving the way for future studies of complex systems at the nanoscale.
Numerical perturbative methods in the quantum theory of physical systems
International Nuclear Information System (INIS)
Adam, G.
1980-01-01
During the last two decades, development of digital electronic computers has led to the deployment of new, distinct methods in theoretical physics. These methods, based on the advances of modern numerical analysis as well as on specific equations describing physical processes, enabled to perform precise calculations of high complexity which have completed and sometimes changed our image of many physical phenomena. Our efforts have concentrated on the development of numerical methods with such intrinsic performances as to allow a successful approach of some Key issues in present theoretical physics on smaller computation systems. The basic principle of such methods is to translate, in numerical analysis language, the theory of perturbations which is suited to numerical rather than to analytical computation. This idea has been illustrated by working out two problems which arise from the time independent Schroedinger equation in the non-relativistic approximation, within both quantum systems with a small number of particles and systems with a large number of particles, respectively. In the first case, we are led to the numerical solution of some quadratic ordinary differential equations (first section of the thesis) and in the second case, to the solution of some secular equations in the Brillouin area (second section). (author)
Time delay systems theory, numerics, applications, and experiments
Ersal, Tulga; Orosz, Gábor
2017-01-01
This volume collects contributions related to selected presentations from the 12th IFAC Workshop on Time Delay Systems, Ann Arbor, June 28-30, 2015. The included papers present novel techniques and new results of delayed dynamical systems. The topical spectrum covers control theory, numerical analysis, engineering and biological applications as well as experiments and case studies. The target audience primarily comprises research experts in the field of time delay systems, but the book may also be beneficial for graduate students alike. .
Highly uniform parallel microfabrication using a large numerical aperture system
Energy Technology Data Exchange (ETDEWEB)
Zhang, Zi-Yu; Su, Ya-Hui, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [School of Electrical Engineering and Automation, Anhui University, Hefei 230601 (China); Zhang, Chen-Chu; Hu, Yan-Lei; Wang, Chao-Wei; Li, Jia-Wen; Chu, Jia-Ru; Wu, Dong, E-mail: ustcsyh@ahu.edu.cn, E-mail: dongwu@ustc.edu.cn [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Precision Machinery and Precision Instrumentation, University of Science and Technology of China, Hefei 230026 (China)
2016-07-11
In this letter, we report an improved algorithm to produce accurate phase patterns for generating highly uniform diffraction-limited multifocal arrays in a large numerical aperture objective system. It is shown that based on the original diffraction integral, the uniformity of the diffraction-limited focal arrays can be improved from ∼75% to >97%, owing to the critical consideration of the aperture function and apodization effect associated with a large numerical aperture objective. The experimental results, e.g., 3 × 3 arrays of square and triangle, seven microlens arrays with high uniformity, further verify the advantage of the improved algorithm. This algorithm enables the laser parallel processing technology to realize uniform microstructures and functional devices in the microfabrication system with a large numerical aperture objective.
New type radiation management system
International Nuclear Information System (INIS)
Mogi, Kenichi; Uranaka, Yasuo; Fujita, Kazuhiko
2001-01-01
The radiation management system is a system to carry out entrance and leaving room management of peoples into radiation management area, information management on radiation obtained from a radiation testing apparatus, and so on. New type radiation management system developed by the Mitsubishi Electric Corp. is designed by concepts of superior maintenance and system practice by using apparatus and its interface with standard specification, upgrading of processing response by separating exposure management processing from radiation monitoring processing on a computer, and a backup system not so as to lose its function by a single accident of the constructed computer. Therefore, the system is applied by the newest hardware, package software, and general use LAN, and can carry out a total system filled with requirements and functions for various radiation management of customers by preparing a basic system from radiation testing apparatus to entrance and leaving room management system. Here were described on outline of the new type management system, concept of the system, and functions of every testing apparatus. (G.K.)
Comparing numerical methods for the solutions of the Chen system
International Nuclear Information System (INIS)
Noorani, M.S.M.; Hashim, I.; Ahmad, R.; Bakar, S.A.; Ismail, E.S.; Zakaria, A.M.
2007-01-01
In this paper, the Adomian decomposition method (ADM) is applied to the Chen system which is a three-dimensional system of ODEs with quadratic nonlinearities. The ADM yields an analytical solution in terms of a rapidly convergent infinite power series with easily computable terms. Comparisons between the decomposition solutions and the classical fourth-order Runge-Kutta (RK4) numerical solutions are made. In particular we look at the accuracy of the ADM as the Chen system changes from a non-chaotic system to a chaotic one. To highlight some computational difficulties due to a high Lyapunov exponent, a comparison with the Lorenz system is given
A review of numerical simulation of hydrothermal systems.
Mercer, J.W.; Faust, C.R.
1979-01-01
Many advances in simulating single and two-phase fluid flow and heat transport in porous media have recently been made in conjunction with geothermal energy research. These numerical models reproduce system thermal and pressure behaviour and can be used for other heat-transport problems, such as high-level radioactive waste disposal and heat-storage projects. -Authors
On a numerical algorithm for uncertain system | Abiola | Science ...
African Journals Online (AJOL)
A numerical method for computing stable control signals for system with bounded input disturbance is developed. The algorithm is an elaboration of the gradient technique and variable metric method for computing control variables in linear and non-linear optimization problems. This method is developed for an integral ...
China's numerical management system for reducing national energy intensity
International Nuclear Information System (INIS)
Li, Huimin; Zhao, Xiaofan; Yu, Yuqing; Wu, Tong; Qi, Ye
2016-01-01
In China, the national target for energy intensity reduction, when integrated with target disaggregation and information feedback systems, constitutes a numerical management system, which is a hallmark of modern governance. This paper points out the technical weaknesses of China's current numerical management system. In the process of target disaggregation, the national target cannot be fully disaggregated to local governments, sectors and enterprises without omissions. At the same time, governments at lower levels face pressure for reducing energy intensity that exceeds their respective jurisdictions. In the process of information feedback, information failure is inevitable due to statistical inaccuracy. Furthermore, the monitoring system is unable to correct all errors, and data verification plays a limited role in the examination system. To address these problems, we recommend that the government: use total energy consumption as the primary indicator of energy management; reform the accounting and reporting of energy statistics toward greater consistency, timeliness and transparency; clearly define the responsibility of the higher levels of government. - Highlights: •We assess drawbacks of China's numerical management system for energy intensity. •The national energy intensity target cannot be fully disaggregated without omissions. •Data distortion is due to failures in statistics, monitoring and examination system. •Lower-level governments’ ability to meet energy target is weaker than their pressure. •We provide three policy recommendations for China's policy-makers.
A qualitative numerical study of high dimensional dynamical systems
Albers, David James
Since Poincare, the father of modern mathematical dynamical systems, much effort has been exerted to achieve a qualitative understanding of the physical world via a qualitative understanding of the functions we use to model the physical world. In this thesis, we construct a numerical framework suitable for a qualitative, statistical study of dynamical systems using the space of artificial neural networks. We analyze the dynamics along intervals in parameter space, separating the set of neural networks into roughly four regions: the fixed point to the first bifurcation; the route to chaos; the chaotic region; and a transition region between chaos and finite-state neural networks. The study is primarily with respect to high-dimensional dynamical systems. We make the following general conclusions as the dimension of the dynamical system is increased: the probability of the first bifurcation being of type Neimark-Sacker is greater than ninety-percent; the most probable route to chaos is via a cascade of bifurcations of high-period periodic orbits, quasi-periodic orbits, and 2-tori; there exists an interval of parameter space such that hyperbolicity is violated on a countable, Lebesgue measure 0, "increasingly dense" subset; chaos is much more likely to persist with respect to parameter perturbation in the chaotic region of parameter space as the dimension is increased; moreover, as the number of positive Lyapunov exponents is increased, the likelihood that any significant portion of these positive exponents can be perturbed away decreases with increasing dimension. The maximum Kaplan-Yorke dimension and the maximum number of positive Lyapunov exponents increases linearly with dimension. The probability of a dynamical system being chaotic increases exponentially with dimension. The results with respect to the first bifurcation and the route to chaos comment on previous results of Newhouse, Ruelle, Takens, Broer, Chenciner, and Iooss. Moreover, results regarding the high
Efficient numerical simulations of many-body localized systems
Energy Technology Data Exchange (ETDEWEB)
Pollmann, Frank [Max-Planck-Institut fuer Physik komplexer Systeme, 01187 Dresden (Germany); Khemani, Vedika; Sondhi, Shivaji [Physics Department, Princeton University, Princeton, NJ 08544 (United States)
2016-07-01
Many-body localization (MBL) occurs in isolated quantum systems when Anderson localization persists in the presence of finite interactions. To understand this phenomenon, the development of new, efficient numerical methods to find highly excited eigenstates is essential. We introduce a variant of the density-matrix renormalization group (DMRG) method that obtains individual highly excited eigenstates of MBL systems to machine precision accuracy at moderate-large disorder. This method explicitly takes advantage of the local spatial structure characterizing MBL eigenstates.
Practical integrated simulation systems for coupled numerical simulations in parallel
Energy Technology Data Exchange (ETDEWEB)
Osamu, Hazama; Zhihong, Guo [Japan Atomic Energy Research Inst., Centre for Promotion of Computational Science and Engineering, Tokyo (Japan)
2003-07-01
In order for the numerical simulations to reflect 'real-world' phenomena and occurrences, incorporation of multidisciplinary and multi-physics simulations considering various physical models and factors are becoming essential. However, there still exist many obstacles which inhibit such numerical simulations. For example, it is still difficult in many instances to develop satisfactory software packages which allow for such coupled simulations and such simulations will require more computational resources. A precise multi-physics simulation today will require parallel processing which again makes it a complicated process. Under the international cooperative efforts between CCSE/JAERI and Fraunhofer SCAI, a German institute, a library called the MpCCI, or Mesh-based Parallel Code Coupling Interface, has been implemented together with a library called STAMPI to couple two existing codes to develop an 'integrated numerical simulation system' intended for meta-computing environments. (authors)
Numerical heat transfer studies of PCMs used in a box-type solar cooker
Energy Technology Data Exchange (ETDEWEB)
Chen, C.R.; Sharma, Atul [Department of Mechanical Engineering, Kun Shan University, 949 Da-Wan Road, Yung-Kung City, Tainan Hsien 710 (China); Tyagi, S.K. [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (China); Buddhi, D. [Thermal Energy Storage Laboratory, School of Energy and Environmental Studies, Khandwa Road Campus, Devi Ahilya University, Indore 452017 (India)
2008-05-15
Theoretical investigations on the phase change materials (PCMs) used as the heat storage media for box-type solar cookers have been conducted in this study. The selected PCMs are magnesium nitrate hexahydrate, stearic acid, acetamide, acetanilide and erythritol. For a two-dimensional simulation model based on the enthalpy approach, calculations have been made for the melt fraction with conduction only. Different materials such as glass, stainless steel, tin, aluminum mixed, aluminum and copper are used as the heat exchanger container materials in the numerical calculations. The large value of thermal conductivity of heat exchanger container material did not make a significant contribution on the melt fraction except for at very low thermal conductivities. Based on the theoretical results, stearic acid and acetamide are found to be good compatibility with latent heat storage system. It is also found that the initial temperature of PCM does not have very important effects on the melting time, while the boundary wall temperature plays an important role during the melting and has a strong effect on the melt fraction. The results also show that the effect of thickness of container material on the melt fraction is insignificant. The results obtained in this paper show that in a box-type solar cooker, acetamide and stearic acid should be used as a latent heat storage materials. (author)
Numerical study of a novel dew point evaporative cooling system
Energy Technology Data Exchange (ETDEWEB)
Riangvilaikul, B.; Kumar, S. [Energy Field of Study, School of Environment, Resources and Development, Asian Institute of Technology, P.O. Box 4, Klong Luang, Pathumthani 12120 (Thailand)
2010-11-15
Dew point evaporative cooling system is an alternative to vapor compression air conditioning system for sensible cooling of ventilation air. This paper presents the theoretical performance of a novel dew point evaporative cooling system operating under various inlet air conditions (covering dry, moderate and humid climate) and influence of major operating parameters (namely, velocity, system dimension and the ratio of working air to intake air). A model of the dew point evaporative cooling system has been developed to simulate the heat and mass transfer processes. The outlet air conditions and system effectiveness predicted by the model using numerical method for known inlet parameters have been validated with experimental findings and with recent literature. The model was used to optimize the system parameters and to investigate the system effectiveness operating under various inlet air conditions. (author)
International Nuclear Information System (INIS)
Meshii, Toshio; Maita, Yasushi; Hirota, Koichi; Kamishima, Yoshio.
1988-01-01
When the reduction of the construction cost of FBRs is considered from the standpoint of the machinery and equipment, to make the size small and to heighten the efficiency are the assigned mission. In order to make a reactor vessel small, it is indispensable to decrease the size of the equipment for fuel exchange installed on the upper part of a core. Mitsubishi Heavy Industries Ltd. carried out the research on the development of a new type fuel exchange system. As for the fuel exchange system for FBRs, it is necessary to change the mode of fuel exchange from that of LWRs, such as handling in the presence of chemically active sodium and inert argon atmosphere covering it and handling under heavy shielding against high radiation. The fuel exchange system for FBRs is composed of a fuel exchanger which inserts, pulls out and transfers fuel and rotary plugs. The mechanism adopted for the new type fuel exchange system that Mitsubishi is developing is explained. The feasibility of the mechanism on the upper part of a core was investigated by water flow test, vibration test and buckling test. The design of the mechanism on the upper part of the core of a demonstration FBR was examined, and the new type fuel exchange system was sufficiently applicable. (Kako, I.)
Biofouling in forward osmosis systems: An experimental and numerical study.
Bucs, Szilárd S; Valladares Linares, Rodrigo; Vrouwenvelder, Johannes S; Picioreanu, Cristian
2016-12-01
This study evaluates with numerical simulations supported by experimental data the impact of biofouling on membrane performance in a cross-flow forward osmosis (FO) system. The two-dimensional numerical model couples liquid flow with solute transport in the FO feed and draw channels, in the FO membrane support layer and in the biofilm developed on one or both sides of the membrane. The developed model was tested against experimental measurements at various osmotic pressure differences and in batch operation without and with the presence of biofilm on the membrane active layer. Numerical studies explored the effect of biofilm properties (thickness, hydraulic permeability and porosity), biofilm membrane surface coverage, and biofilm location on salt external concentration polarization and on the permeation flux. The numerical simulations revealed that (i) when biofouling occurs, external concentration polarization became important, (ii) the biofilm hydraulic permeability and membrane surface coverage have the highest impact on water flux, and (iii) the biofilm formed in the draw channel impacts the process performance more than when formed in the feed channel. The proposed mathematical model helps to understand the impact of biofouling in FO membrane systems and to develop possible strategies to reduce and control biofouling. Copyright © 2016 Elsevier Ltd. All rights reserved.
Biofouling in forward osmosis systems: An experimental and numerical study
Bucs, Szilard
2016-09-20
This study evaluates with numerical simulations supported by experimental data the impact of biofouling on membrane performance in a cross-flow forward osmosis (FO) system. The two-dimensional numerical model couples liquid flow with solute transport in the FO feed and draw channels, in the FO membrane support layer and in the biofilm developed on one or both sides of the membrane. The developed model was tested against experimental measurements at various osmotic pressure differences and in batch operation without and with the presence of biofilm on the membrane active layer. Numerical studies explored the effect of biofilm properties (thickness, hydraulic permeability and porosity), biofilm membrane surface coverage, and biofilm location on salt external concentration polarization and on the permeation flux. The numerical simulations revealed that (i) when biofouling occurs, external concentration polarization became important, (ii) the biofilm hydraulic permeability and membrane surface coverage have the highest impact on water flux, and (iii) the biofilm formed in the draw channel impacts the process performance more than when formed in the feed channel. The proposed mathematical model helps to understand the impact of biofouling in FO membrane systems and to develop possible strategies to reduce and control biofouling. © 2016 Elsevier Ltd
Directory of Open Access Journals (Sweden)
Gary R. Nicklason
2015-07-01
Full Text Available We consider center conditions for plane polynomial systems of Abel type consisting of a linear center perturbed by the sum of 2 homogeneous polynomials of degrees n and 2n-1 where $n \\ge 2$. Using properties of Abel equations we obtain two general systems valid for arbitrary values on n. For the cubic n=2 systems we find several sets of new center conditions, some of which show that the results in a paper by Hill, Lloyd and Pearson which were conjectured to be complete are in fact not complete. We also present a particular system which appears to be a counterexample to a conjecture by Zoladek et al. regarding rational reversibility in cubic polynomial systems.
Numerical simulation system for environmental studies: SPEEDI-MP
International Nuclear Information System (INIS)
Nagai, Haruyasu; Chino, Masamichi; Terada, Hiroaki; Harayama, Takaya; Kobayashi, Takuya; Tsuduki, Katsunori; Kim, Keyong-Ok; Furuno, Akiko
2006-09-01
A numerical simulation system SPEEDI-MP has been developed to apply for various environmental studies. SPEEDI-MP consists of dynamical models and material transport models for the atmospheric, terrestrial, and oceanic environments, meteorological and geographical database for model inputs, and system utilities for file management, visualization, analysis, etc., using graphical user interfaces (GUIs). As a numerical simulation tool, a model coupling program (model coupler) has been developed. It controls parallel calculations of several models and data exchanges among them to realize the dynamical coupling of the models. A coupled model system for water circulation has been constructed with atmosphere, ocean, wave, hydrology, and land-surface models using the model coupler. System utility GUIs are based on the Web technology, allowing users to manipulate all the functions on the system using their own PCs via the internet. In this system, the source estimation function in the atmospheric transport model can be executed on the grid computer system. Performance tests of the coupled model system for water circulation were also carried out for the flood event at Saudi Arabia in January 2005 and the storm surge case by the hurricane KATRINA in August 2005. (author)
Current system of the solar wind: results of numerical calculation
International Nuclear Information System (INIS)
Pisanko, Yu.V.
1985-01-01
Results of numerical calculations of surface current in the interplanetary current layer and steady volume current in the solar wind for heliocentric distances (1-10)Rsub(s) (Rsub(s) is the Sun radius) are given. The strength of current dependence on spatial coordinates is considered. Stationary nondissipative magnetohydrodynamic corona expansion (SNMCE) in the reference system rotating with the Sun is studied. Calculations show that three-dimensional current system of nonaxial-symmetric and nonsymmetric relatively to helioequator plane of SNMCE is more complicated than the zonal ring current around the Sun, which is the only component of the current system in spatial symmetric case
NUMERICAL THERMAL ANALYSIS OF A CAR BRAKING SYSTEM
Directory of Open Access Journals (Sweden)
Patryk Różyło
2017-06-01
Full Text Available The study involved performing a numerical thermal analysis of selected components in a car braking system. The primary goal of the study was to determine the regions which are the most susceptible to variations in temperature, and to determine the degree of thermal impact upon them. The analysis was performed using the Abaqus environment. The examined components of the braking system were made of materials reflecting the mechanical properties of the real subassemblies. The FEM analysis enabled determination of the distribution of temperature in the system with respect to the properties of the investigated materials and applied boundary conditions.
Rosenbaum, J. S.
1976-01-01
If a system of ordinary differential equations represents a property conserving system that can be expressed linearly (e.g., conservation of mass), it is then desirable that the numerical integration method used conserve the same quantity. It is shown that both linear multistep methods and Runge-Kutta methods are 'conservative' and that Newton-type methods used to solve the implicit equations preserve the inherent conservation of the numerical method. It is further shown that a method used by several authors is not conservative.
SENR /NRPy + : Numerical relativity in singular curvilinear coordinate systems
Ruchlin, Ian; Etienne, Zachariah B.; Baumgarte, Thomas W.
2018-03-01
We report on a new open-source, user-friendly numerical relativity code package called SENR /NRPy + . Our code extends previous implementations of the BSSN reference-metric formulation to a much broader class of curvilinear coordinate systems, making it ideally suited to modeling physical configurations with approximate or exact symmetries. In the context of modeling black hole dynamics, it is orders of magnitude more efficient than other widely used open-source numerical relativity codes. NRPy + provides a Python-based interface in which equations are written in natural tensorial form and output at arbitrary finite difference order as highly efficient C code, putting complex tensorial equations at the scientist's fingertips without the need for an expensive software license. SENR provides the algorithmic framework that combines the C codes generated by NRPy + into a functioning numerical relativity code. We validate against two other established, state-of-the-art codes, and achieve excellent agreement. For the first time—in the context of moving puncture black hole evolutions—we demonstrate nearly exponential convergence of constraint violation and gravitational waveform errors to zero as the order of spatial finite difference derivatives is increased, while fixing the numerical grids at moderate resolution in a singular coordinate system. Such behavior outside the horizons is remarkable, as numerical errors do not converge to zero near punctures, and all points along the polar axis are coordinate singularities. The formulation addresses such coordinate singularities via cell-centered grids and a simple change of basis that analytically regularizes tensor components with respect to the coordinates. Future plans include extending this formulation to allow dynamical coordinate grids and bispherical-like distribution of points to efficiently capture orbiting compact binary dynamics.
A numerical study of boiling flow instability of a reactor thermosyphon system
International Nuclear Information System (INIS)
Nayak, A.K.; Lathouwers, D.; Hagen, T.H.J.J. van der; Schrauwen, Frans; Molenaar, Peter; Rogers, Andrew
2006-01-01
A numerical study has been carried out to investigate the boiling flow instability of a reactor thermosyphon system. The numerical model solves the conservation equations of mass, momentum and energy applicable to a two-fluid and three-field steam-water system using a finite difference technique. The computer code MONA was used for this purpose. The code was applied to the thermosyphon system of an EO (ethylene oxide) chemical reactor in which the heat released by a catalytic reaction is carried by boiling water under natural circulation conditions. The steady-state characteristics of the reactor thermosyphon system were predicted using the MONA code and conventional two-phase flow models in order to understand the model applicability for this type of thermosyphon system. The two-fluid model was found to predict the flow closest to the measured value of the plant. The stability behaviour of the thermosyphon system was investigated for a wide range of operating conditions. The effects of power, subcooling, riser length and riser diameter on the boiling flow instability were determined. The system was found to be unstable at higher power conditions which is typical for a Type II instability. However, with an increase in riser diameter, oscillations at low power were observed as well. These are classified as Type I instabilities. Stability maps were predicted for both Type I and Type II instabilities. Methods of improving the stability of the system are discussed
A numerical study of boiling flow instability of a reactor thermosyphon system
Energy Technology Data Exchange (ETDEWEB)
Nayak, A.K.; Lathouwers, D.; Hagen, T.H.J.J. van der [Interfaculty Reactor Institute, Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Schrauwen, Frans; Molenaar, Peter; Rogers, Andrew [Shell Research and Technology Centre, Badhuisweg 3, 1031 CM Amsterdam (Netherlands)
2006-04-01
A numerical study has been carried out to investigate the boiling flow instability of a reactor thermosyphon system. The numerical model solves the conservation equations of mass, momentum and energy applicable to a two-fluid and three-field steam-water system using a finite difference technique. The computer code MONA was used for this purpose. The code was applied to the thermosyphon system of an EO (ethylene oxide) chemical reactor in which the heat released by a catalytic reaction is carried by boiling water under natural circulation conditions. The steady-state characteristics of the reactor thermosyphon system were predicted using the MONA code and conventional two-phase flow models in order to understand the model applicability for this type of thermosyphon system. The two-fluid model was found to predict the flow closest to the measured value of the plant. The stability behaviour of the thermosyphon system was investigated for a wide range of operating conditions. The effects of power, subcooling, riser length and riser diameter on the boiling flow instability were determined. The system was found to be unstable at higher power conditions which is typical for a Type II instability. However, with an increase in riser diameter, oscillations at low power were observed as well. These are classified as Type I instabilities. Stability maps were predicted for both Type I and Type II instabilities. Methods of improving the stability of the system are discussed. [Author].
ON A NUMERICAL ALGORITHM FOR UNCERTAIN SYSTEM ∫ Φ ...
African Journals Online (AJOL)
Administrator
Science World Journal Vol 7 (No 1) 2012 www.scienceworldjournal.org. ISSN 1597-6343. On a Numerical Algorithm for Uncertain System. Newton's Algorithm. Step 1 Calculate. )(),().(k k k. xAxgxF. Step 2. Check if ε. <. )(k xg for a predetermined ,ε if so stop, else. Step3. Set k k. PxA. )( = )(k xg. -. Step4. Set k k k. Px x. +. = +1.
Modelling of multidimensional quantum systems by the numerical functional integration
International Nuclear Information System (INIS)
Lobanov, Yu.Yu.; Zhidkov, E.P.
1990-01-01
The employment of the numerical functional integration for the description of multidimensional systems in quantum and statistical physics is considered. For the multiple functional integrals with respect to Gaussian measures in the full separable metric spaces the new approximation formulas exact on a class of polynomial functionals of a given summary degree are constructed. The use of the formulas is demonstrated on example of computation of the Green function and the ground state energy in multidimensional Calogero model. 15 refs.; 2 tabs
Numerical Three-Dimensional Model of Airport Terminal Drainage System
Directory of Open Access Journals (Sweden)
Strzelecki Michał
2014-03-01
Full Text Available During the construction of an airport terminal it was found that as a result of the hydrostatic pressure of underground water the foundation plate of the building had dangerously shifted in the direction opposite to that of the gravitational forces. The only effective measure was to introduce a drainage system on the site. The complex geology of the area indicated that two independent drainage systems, i.e., a horizontal system in the Quaternary beds and a vertical system in the Tertiary water-bearing levels, were necessary. This paper presents numerical FEM calculations of the two drainage systems being part of the airport terminal drainaged esign. The computer simulation which was carried out took into consideration the actual effect of the drainage systems and their impact on the depression cone being formed in the two aquifers.
Numerical evaluation of two-center integrals over Slater type orbitals
Energy Technology Data Exchange (ETDEWEB)
Kurt, S. A., E-mail: slaykurt@gmail.com [Department of Physics, Natural Sciences Institute, Ondokuz Mayıs University, 55139, Samsun (Turkey); Yükçü, N., E-mail: nyukcu@gmail.com [Department of Energy Systems Engineering, Faculty of Technology, Adıyaman University, 02040, Adıyaman (Turkey)
2016-03-25
Slater Type Orbitals (STOs) which one of the types of exponential type orbitals (ETOs) are used usually as basis functions in the multicenter molecular integrals to better understand physical and chemical properties of matter. In this work, we develop algorithms for two-center overlap and two-center two-electron hybrid and Coulomb integrals which are calculated with help of translation method for STOs and some auxiliary functions by V. Magnasco’s group. We use Mathematica programming language to produce algorithms for these calculations. Numerical results for some quantum numbers are presented in the tables. Consequently, we compare our obtained numerical results with the other known literature results and other details of evaluation method are discussed.
A Study of Enhanced, Higher Order Boussinesq-Type Equations and Their Numerical Modelling
DEFF Research Database (Denmark)
Banijamali, Babak
model is designated for the solution of higher-order Boussinesq-type equations, formulated in terms of the horizontal velocity at an arbitrary depth vector. Various discretisation techniques and grid definitions have been considered in this endeavour, undertaking a detailed analysis of the selected......This project has encompassed efforts in two separate veins: on the one hand, the acquiring of highly accurate model equations of the Boussinesq-type, and on the other hand, the theoretical and practical work in implementing such equations in the form of conventional numerical models, with obvious...... potential for applications to the realm of numerical modelling in coastal engineering. The derivation and analysis of several forms of higher-order in dispersion and non-linearity Boussinesq-type equations have been undertaken, obtaining and investigating the properties of a new and generalised class...
Numerical evaluation of two-center integrals over Slater type orbitals
International Nuclear Information System (INIS)
Kurt, S. A.; Yükçü, N.
2016-01-01
Slater Type Orbitals (STOs) which one of the types of exponential type orbitals (ETOs) are used usually as basis functions in the multicenter molecular integrals to better understand physical and chemical properties of matter. In this work, we develop algorithms for two-center overlap and two-center two-electron hybrid and Coulomb integrals which are calculated with help of translation method for STOs and some auxiliary functions by V. Magnasco’s group. We use Mathematica programming language to produce algorithms for these calculations. Numerical results for some quantum numbers are presented in the tables. Consequently, we compare our obtained numerical results with the other known literature results and other details of evaluation method are discussed.
Dynamical Systems Method and Applications Theoretical Developments and Numerical Examples
Ramm, Alexander G
2012-01-01
Demonstrates the application of DSM to solve a broad range of operator equations The dynamical systems method (DSM) is a powerful computational method for solving operator equations. With this book as their guide, readers will master the application of DSM to solve a variety of linear and nonlinear problems as well as ill-posed and well-posed problems. The authors offer a clear, step-by-step, systematic development of DSM that enables readers to grasp the method's underlying logic and its numerous applications. Dynamical Systems Method and Applications begins with a general introduction and
Napolskich, Vladimir
2003-01-01
Rmt.: Balzhek, Václav. Numerals. Comparative-etymological analyses of numeral systems and their implications (saharan, nubian, egyptian, berber, kartvelian, ralic, altaic and indo-european languages). Brno, 1999. (Spisy Masarykovy Univerzity v Brné. Filozofická fakulta; 322). Ülevaade uurali keelte arvsõnu käsitlevast osast
Numerical Diffusion Effect in Dynamic Simulation of Thermohydraulic Systems
International Nuclear Information System (INIS)
Zanocco, Pablo; Gimenez, Marcelo; Delmastro, Dario
2003-01-01
In this work, the behavior of the explicit - up-wind method is studied in two phase natural convection circuit, near the instabilities boundaries.The effect of the numerical diffusion of the scheme upon the system stability is evaluated by means of linearization by small perturbations.The results are compared with a non-diffusive method, in the frequency domain, that solves analytically the linearized equations around a steady state condition.Moreover, a conservation equation transport model using the method of characteristics is implemented and studied.This method is compared with the explicit - up-wind scheme and it is found that it significantly reduces numerical diffusion in the equations solution. Several advantages are visualized for particular cases
In silico dissection of Type VII Secretion System components across
Indian Academy of Sciences (India)
Type VII Secretion System (T7SS) is one of the factors involved in virulence of Mycobacteriun tuberculosis H37Rv. Numerous research efforts have been made in the last decade towards characterizing the components of this secretion system. An extensive genome-wide analysis through compilation of isolated information ...
The chaotic region of Lorenz-type system in the parametric space
International Nuclear Information System (INIS)
Liao Haohui; Zhou Tianshou; Tang Yun
2004-01-01
A Lorenz-type system is introduced in this paper. The system contains as special cases the Lorenz system, Chen system and Lue system. The distribution of chaos of the system in the parametric space is numerically investigated. At the same time a set of conditions for possible existence of chaos are given, which guideline the range of searching chaos in the numerical simulation
Numerical modeling and design of a disk-type rotating permanent magnet induction pump
Energy Technology Data Exchange (ETDEWEB)
Koroteeva, E., E-mail: koroteeva@physics.msu.ru [Institute of Physics of University of Latvia, Salaspils 2169 (Latvia); Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Ščepanskis, M. [Laboratory for Mathematical Modelling of Environmental and Technological Processes, University of Latvia, Rīga 1002 (Latvia); Bucenieks, I.; Platacis, E. [Institute of Physics of University of Latvia, Salaspils 2169 (Latvia)
2016-05-15
Highlights: • The design and performance of a disk-type induction pump are described. • A 3D numerical model based on an iterative coupling between EM and hydrodynamic solvers is developed. • The model is verified by comparing with the experiments in a Pb-Bi loop facility. • The suggestions are given to estimate the pump performance in a Pb-Li loop at high pressures. - Abstract: Electromagnetic induction pumps with rotating permanent magnets appear to be the most promising devices to transport liquid metals in high-temperature applications. Here we present a numerical methodology to simulate the operation of one particular modification of these types of pumps: a disk-type induction pump. The numerical model allows for the calculation and analysis of the flow parameters, including the pressure–flow rate characteristics of the pump. The simulations are based on an iterative fully coupled scheme for electromagnetic and hydrodynamic solvers. The developed model is verified by comparing with experimental data obtained using a Pb-Bi loop test facility, for pressures up to 4 bar and flow rates up to 9 kg/s. The verified model is then expanded to higher pressures, beyond the limits of the experimental loop. Based on the numerical simulations, suggestions are given to extrapolate experimental data to higher (industrially important) pressure ranges. Using the numerical model and analytical estimation, the pump performance for the Pb-Li loop is also examined, and the ability of the designed pump to develop pressure heads over 6 bar and to provide flow rates over 15 kg/s is shown.
Numerical Cerebrospinal System Modeling in Fluid-Structure Interaction.
Garnotel, Simon; Salmon, Stéphanie; Balédent, Olivier
2018-01-01
Cerebrospinal fluid (CSF) stroke volume in the aqueduct is widely used to evaluate CSF dynamics disorders. In a healthy population, aqueduct stroke volume represents around 10% of the spinal stroke volume while intracranial subarachnoid space stroke volume represents 90%. The amplitude of the CSF oscillations through the different compartments of the cerebrospinal system is a function of the geometry and the compliances of each compartment, but we suspect that it could also be impacted be the cardiac cycle frequency. To study this CSF distribution, we have developed a numerical model of the cerebrospinal system taking into account cerebral ventricles, intracranial subarachnoid spaces, spinal canal and brain tissue in fluid-structure interactions. A numerical fluid-structure interaction model is implemented using a finite-element method library to model the cerebrospinal system and its interaction with the brain based on fluid mechanics equations and linear elasticity equations coupled in a monolithic formulation. The model geometry, simplified in a first approach, is designed in accordance with realistic volume ratios of the different compartments: a thin tube is used to mimic the high flow resistance of the aqueduct. CSF velocity and pressure and brain displacements are obtained as simulation results, and CSF flow and stroke volume are calculated from these results. Simulation results show a significant variability of aqueduct stroke volume and intracranial subarachnoid space stroke volume in the physiological range of cardiac frequencies. Fluid-structure interactions are numerous in the cerebrospinal system and difficult to understand in the rigid skull. The presented model highlights significant variations of stroke volumes under cardiac frequency variations only.
Nie, Yihua; Tang, Saiqian; Xu, Yang; Mao, Kunli
2018-04-01
In order to obtain mechanical response distribution of herringbone frame structure for highway subgrade slopes protection and select the best structure type, 3D numerical models of three types herringbone frame structure were established and analyzed in finite element software ANSYS. Indoor physical model of soil slope protected by herringbone frame structure was built and mechanical response of the frame structure was measured by loading tests. Numerical results indicate slope foot is the stress most disadvantageous location. Comparative analysis shows that structure composed of mortar rubble base layer and precast concrete blocks paving layer is the best one for resisting deformation and structure with cement mortar base layer and precast concrete blocks paving layer is the best one for being of low stress.
Numerical continuation methods for dynamical systems path following and boundary value problems
Krauskopf, Bernd; Galan-Vioque, Jorge
2007-01-01
Path following in combination with boundary value problem solvers has emerged as a continuing and strong influence in the development of dynamical systems theory and its application. It is widely acknowledged that the software package AUTO - developed by Eusebius J. Doedel about thirty years ago and further expanded and developed ever since - plays a central role in the brief history of numerical continuation. This book has been compiled on the occasion of Sebius Doedel''s 60th birthday. Bringing together for the first time a large amount of material in a single, accessible source, it is hoped that the book will become the natural entry point for researchers in diverse disciplines who wish to learn what numerical continuation techniques can achieve. The book opens with a foreword by Herbert B. Keller and lecture notes by Sebius Doedel himself that introduce the basic concepts of numerical bifurcation analysis. The other chapters by leading experts discuss continuation for various types of systems and objects ...
Reactions, accuracy and response complexity of numerical typing on touch screens.
Lin, Cheng-Jhe; Wu, Changxu
2013-01-01
Touch screens are popular nowadays as seen on public kiosks, industrial control panels and personal mobile devices. Numerical typing is one frequent task performed on touch screens, but this task on touch screen is subject to human errors and slow responses. This study aims to find innate differences of touch screens from standard physical keypads in the context of numerical typing by eliminating confounding issues. Effects of precise visual feedback and urgency of numerical typing were also investigated. The results showed that touch screens were as accurate as physical keyboards, but reactions were indeed executed slowly on touch screens as signified by both pre-motor reaction time and reaction time. Provision of precise visual feedback caused more errors, and the interaction between devices and urgency was not found on reaction time. To improve usability of touch screens, designers should focus more on reducing response complexity and be cautious about the use of visual feedback. The study revealed that slower responses on touch screens involved more complex human cognition to formulate motor responses. Attention should be given to designing precise visual feedback appropriately so that distractions or visual resource competitions can be avoided to improve human performance on touch screens.
Numerical Analysis for Dynamic Instability of Electrodynamic Maglev Systems
Directory of Open Access Journals (Sweden)
Y. Cai
1995-01-01
Full Text Available Suspension instabilities in an electrodynamic maglev system with three- and five-degrees-of-freedom DOF vehicles traveling on a double L-shaped set of guideway conductors were investigated with various experimentally measured magnetic force data incorporated into theoretical models. Divergence and flutter were obtained from both analytical and numerical solutions for coupled vibration of the three-DOF maglev vehicle model. Instabilities of five direction motion (heave, slip, roll, pitch, and yaw were observed for the five-DOF vehicle model. The results demonstrate that system parameters such as system damping, vehicle geometry, and coupling effects among five different motions play very important roles in the occurrence of dynamic instabilities of maglev vehicles.
Operational Numerical Weather Prediction systems based on Linux cluster architectures
International Nuclear Information System (INIS)
Pasqui, M.; Baldi, M.; Gozzini, B.; Maracchi, G.; Giuliani, G.; Montagnani, S.
2005-01-01
The progress in weather forecast and atmospheric science has been always closely linked to the improvement of computing technology. In order to have more accurate weather forecasts and climate predictions, more powerful computing resources are needed, in addition to more complex and better-performing numerical models. To overcome such a large computing request, powerful workstations or massive parallel systems have been used. In the last few years, parallel architectures, based on the Linux operating system, have been introduced and became popular, representing real high performance-low cost systems. In this work the Linux cluster experience achieved at the Laboratory far Meteorology and Environmental Analysis (LaMMA-CNR-IBIMET) is described and tips and performances analysed
Numerical Analysis of Combined Valve Hydrodynamic Characteristics for Turbine System
Energy Technology Data Exchange (ETDEWEB)
Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Arif, M.; Suh, Kune Y. [Seoul National Univ., Seoul (Korea, Republic of)
2014-05-15
precisely by the valve manufacturer. As a matter of fact, attempts were made to obtain flow characteristic curves resorting to analytical as well as numerical methods. The flow characteristic curve relates the stem lift with mass flow rate at a specific temperature and pressure. This paper focuses on computational and numerical analysis of the combined stop and control valve. Combined Airflow Regulation Analysis (CARA) is performed to check on the hydrodynamic characteristic, which is represented by flow coefficient characteristic. CATIA V.5 and ANSYS CFX are used for three-dimensional computer-aided design and computational fluid dynamics (CFD) analysis, respectively. Flow characteristic curves are plotted by calculating theoretical and numerical mass flow rate. Hydrodynamic analysis was made of the combined stop and control valve for the turbine system using ANSYS CFX. The result of the numerical study represented by the valve flow coefficient with different normalized values of valve stem movement L/D and different pressure ratios of valve outlet and inlet agrees well with the ideal case and other similar previous experimental results. This study also provided a solid understanding with versatile options for analyzing the hydrodynamics of the combined valve considering the various internal geometry, seat, plug, and the inlet plus outlet boundary conditions to improve the efficiency, performance and reliability of the turbine system of small as well as large power conversion system using the numerical analysis with minimal cost and time.
Numerical Analysis of Combined Valve Hydrodynamic Characteristics for Turbine System
International Nuclear Information System (INIS)
Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Arif, M.; Suh, Kune Y.
2014-01-01
precisely by the valve manufacturer. As a matter of fact, attempts were made to obtain flow characteristic curves resorting to analytical as well as numerical methods. The flow characteristic curve relates the stem lift with mass flow rate at a specific temperature and pressure. This paper focuses on computational and numerical analysis of the combined stop and control valve. Combined Airflow Regulation Analysis (CARA) is performed to check on the hydrodynamic characteristic, which is represented by flow coefficient characteristic. CATIA V.5 and ANSYS CFX are used for three-dimensional computer-aided design and computational fluid dynamics (CFD) analysis, respectively. Flow characteristic curves are plotted by calculating theoretical and numerical mass flow rate. Hydrodynamic analysis was made of the combined stop and control valve for the turbine system using ANSYS CFX. The result of the numerical study represented by the valve flow coefficient with different normalized values of valve stem movement L/D and different pressure ratios of valve outlet and inlet agrees well with the ideal case and other similar previous experimental results. This study also provided a solid understanding with versatile options for analyzing the hydrodynamics of the combined valve considering the various internal geometry, seat, plug, and the inlet plus outlet boundary conditions to improve the efficiency, performance and reliability of the turbine system of small as well as large power conversion system using the numerical analysis with minimal cost and time
Numerical Simulation of Tubular Pumping Systems with Different Regulation Methods
Zhu, Honggeng; Zhang, Rentian; Deng, Dongsheng; Feng, Xusong; Yao, Linbi
2010-06-01
Since the flow in tubular pumping systems is basically along axial direction and passes symmetrically through the impeller, most satisfying the basic hypotheses in the design of impeller and having higher pumping system efficiency in comparison with vertical pumping system, they are being widely applied to low-head pumping engineering. In a pumping station, the fluctuation of water levels in the sump and discharge pool is most common and at most time the pumping system runs under off-design conditions. Hence, the operation of pump has to be flexibly regulated to meet the needs of flow rates, and the selection of regulation method is as important as that of pump to reduce operation cost and achieve economic operation. In this paper, the three dimensional time-averaged Navier-Stokes equations are closed by RNG κ-ɛ turbulent model, and two tubular pumping systems with different regulation methods, equipped with the same pump model but with different designed system structures, are numerically simulated respectively to predict the pumping system performances and analyze the influence of regulation device and help designers make final decision in the selection of design schemes. The computed results indicate that the pumping system with blade-adjusting device needs longer suction box, and the increased hydraulic loss will lower the pumping system efficiency in the order of 1.5%. The pumping system with permanent magnet motor, by means of variable speed regulation, obtains higher system efficiency partly for shorter suction box and partly for different structure design. Nowadays, the varied speed regulation is realized by varied frequency device, the energy consumption of which is about 3˜4% of output power of the motor. Hence, when the efficiency of variable frequency device is considered, the total pumping system efficiency will probably be lower.
Expert System Architecture for Rocket Engine Numerical Simulators: A Vision
Mitra, D.; Babu, U.; Earla, A. K.; Hemminger, Joseph A.
1998-01-01
Simulation of any complex physical system like rocket engines involves modeling the behavior of their different components using mostly numerical equations. Typically a simulation package would contain a set of subroutines for these modeling purposes and some other ones for supporting jobs. A user would create an input file configuring a system (part or whole of a rocket engine to be simulated) in appropriate format understandable by the package and run it to create an executable module corresponding to the simulated system. This module would then be run on a given set of input parameters in another file. Simulation jobs are mostly done for performance measurements of a designed system, but could be utilized for failure analysis or a design job such as inverse problems. In order to use any such package the user needs to understand and learn a lot about the software architecture of the package, apart from being knowledgeable in the target domain. We are currently involved in a project in designing an intelligent executive module for the rocket engine simulation packages, which would free any user from this burden of acquiring knowledge on a particular software system. The extended abstract presented here will describe the vision, methodology and the problems encountered in the project. We are employing object-oriented technology in designing the executive module. The problem is connected to the areas like the reverse engineering of any simulation software, and the intelligent systems for simulation.
Numerical Construction of Viable Sets for Autonomous Conflict Control Systems
Directory of Open Access Journals (Sweden)
Nikolai Botkin
2014-04-01
Full Text Available A conflict control system with state constraints is under consideration. A method for finding viability kernels (the largest subsets of state constraints where the system can be confined is proposed. The method is related to differential games theory essentially developed by N. N. Krasovskii and A. I. Subbotin. The viability kernel is constructed as the limit of sets generated by a Pontryagin-like backward procedure. This method is implemented in the framework of a level set technique based on the computation of limiting viscosity solutions of an appropriate Hamilton–Jacobi equation. To fulfill this, the authors adapt their numerical methods formerly developed for solving time-dependent Hamilton–Jacobi equations arising from problems with state constraints. Examples of computing viability sets are given.
Configuration Management File Manager Developed for Numerical Propulsion System Simulation
Follen, Gregory J.
1997-01-01
One of the objectives of the High Performance Computing and Communication Project's (HPCCP) Numerical Propulsion System Simulation (NPSS) is to provide a common and consistent way to manage applications, data, and engine simulations. The NPSS Configuration Management (CM) File Manager integrated with the Common Desktop Environment (CDE) window management system provides a common look and feel for the configuration management of data, applications, and engine simulations for U.S. engine companies. In addition, CM File Manager provides tools to manage a simulation. Features include managing input files, output files, textual notes, and any other material normally associated with simulation. The CM File Manager includes a generic configuration management Application Program Interface (API) that can be adapted for the configuration management repositories of any U.S. engine company.
Efficient numerical method for district heating system hydraulics
International Nuclear Information System (INIS)
Stevanovic, Vladimir D.; Prica, Sanja; Maslovaric, Blazenka; Zivkovic, Branislav; Nikodijevic, Srdjan
2007-01-01
An efficient method for numerical simulation and analyses of the steady state hydraulics of complex pipeline networks is presented. It is based on the loop model of the network and the method of square roots for solving the system of linear equations. The procedure is presented in the comprehensive mathematical form that could be straightforwardly programmed into a computer code. An application of the method to energy efficiency analyses of a real complex district heating system is demonstrated. The obtained results show a potential for electricity savings in pumps operation. It is shown that the method is considerably more effective than the standard Hardy Cross method still widely used in engineering practice. Because of the ease of implementation and high efficiency, the method presented in this paper is recommended for hydraulic steady state calculations of complex networks
Emulsion type dry cleaning system
International Nuclear Information System (INIS)
Kohanawa, Osamu; Matsumoto, Hiroyo.
1988-01-01
Protective clothing against radioactive contamination used in the radiation controlled areas of nuclear plants has been washed by the same wet washing as used for underwear washing, but recently dry cleaning is getting used in place of wet washing, which generates a large quantity of laundry drain. However, it was required to use wet washing once every five to ten dry cleanings for washing protective clothing, because conventional dry cleaning is less effective in removing water-soluble soils. Therefore, in order to eliminate wet washing, and to decrease the quantity of laundry drains, the emulsion type dry cleaning system capable of removing both oil-soluble and water-soluble soils at a time has been developed. The results of developmental experiments and actual application are presented in this paper. (author)
Numerical modeling of coanda effect in a novel propulsive system
Directory of Open Access Journals (Sweden)
S Das
2016-09-01
Full Text Available Coanda effect (adhesion of jet flow over curved surface is fundamental characteristics of jet flow. In the present paper, we carried out numerical simulations to investigate Coanda flow over a curved surface and its application in a newly proposed Propulsive system "A.C.H.E.O.N" (Aerial Coanda High Efficiency Orienting jet Nozzle which supports thrust vectoring. The ACHEON system is presently being proposed for propelling a new V/STOL airplane in European Union. This system is based on cumulative effects of three physical effects such as (1 High speed jet mixing speeds (2 Coanda effect control by electrostatic fields (3 Coanda effect adhesion of an high speed jet to a convex surface. The performance of this nozzle can be enhanced by increasing the jet deflection angle of synthetic jet over the Coanda surface. This newly proposed nozzle has wide range of applications. It can be used in industrial sector such as plasma spray gun and for direct injection in combustion chamber to enhance the efficiency of the combustion chamber. Also, we studied the effect of Dielectric barrier discharge (DBD plasma actuators on A.C.H.E.O.N system. Dielectric barrier discharge (DBD plasma actuators are active control devices for controlling boundary layer and to delay the flow separation over any convex surfaces. Computations were performed under subsonic condition. Two dimensional CFD calculations were carried out using Reynolds averaged Navier stokes equations (RANS. A numerical method based on finite volume formulation (FVM was used. SST k-ω model was considered to model turbulent flow inside nozzle. DBD model was used to model the plasma. Moreover, a body force treatment was devised to model the effect of plasma and its coupling with the fluid. This preliminary result shows that, the presence of plasma near Coanda surface accelerates the flow and delays the separation and enhances the efficiency of the nozzle.
Combined Effects of Numerical Method Type and Time Step on Water Stressed Actual Crop ET
Directory of Open Access Journals (Sweden)
B. Ghahraman
2016-02-01
Full Text Available Introduction: Actual crop evapotranspiration (Eta is important in hydrologic modeling and irrigation water management issues. Actual ET depends on an estimation of a water stress index and average soil water at crop root zone, and so depends on a chosen numerical method and adapted time step. During periods with no rainfall and/or irrigation, actual ET can be computed analytically or by using different numerical methods. Overal, there are many factors that influence actual evapotranspiration. These factors are crop potential evapotranspiration, available root zone water content, time step, crop sensitivity, and soil. In this paper different numerical methods are compared for different soil textures and different crops sensitivities. Materials and Methods: During a specific time step with no rainfall or irrigation, change in soil water content would be equal to evapotranspiration, ET. In this approach, however, deep percolation is generally ignored due to deep water table and negligible unsaturated hydraulic conductivity below rooting depth. This differential equation may be solved analytically or numerically considering different algorithms. We adapted four different numerical methods, as explicit, implicit, and modified Euler, midpoint method, and 3-rd order Heun method to approximate the differential equation. Three general soil types of sand, silt, and clay, and three different crop types of sensitive, moderate, and resistant under Nishaboor plain were used. Standard soil fraction depletion (corresponding to ETc=5 mm.d-1, pstd, below which crop faces water stress is adopted for crop sensitivity. Three values for pstd were considered in this study to cover the common crops in the area, including winter wheat and barley, cotton, alfalfa, sugar beet, saffron, among the others. Based on this parameter, three classes for crop sensitivity was considered, sensitive crops with pstd=0.2, moderate crops with pstd=0.5, and resistive crops with pstd=0
Composite type nuclear power system
International Nuclear Information System (INIS)
Nakamoto, Koichiro.
1993-01-01
The present invention realizes a high thermal efficiency by heating steams at the exit of a steam generator of a nuclear power plant to high temperature by a thermal super-heating boiler. That is, a thermal superheating boiler is disposed between the steam generator and a turbogenerator to heat steams from the steam generator and supply them to the turbogenerator. In this case, it may be possible that feedwater superheating boiler pipelines to the steam generator are caused to pass through the thermal superheating boiler so that they also have a performance of heating feedwater. If the system of the present invention is used, it is possible to conduct base load operation by nuclear power and a load following operation by controlling the thermal superheating boiler. Further, a hydrogen producing performance is applied to the thermal superheating boiler to produce hydrogen when electric power load is lowered. An internally sustaining type operation method can be conducted of burning hydrogen by the superheating boiler upon increased electric power load. As a result, a power generation system which has an excellent economical property and can easily cope with the load following operation can be attained. (I.S.)
International Nuclear Information System (INIS)
Zamengo, Massimiliano; Funada, Tomohiro; Morikawa, Junko
2017-01-01
Highlights: • Thermal diffusivity of Erythritol was measured by temperature wave method. • Thermal diffusivity was measured in function of temperature and during phase change. • Database of temperature-dependent thermal properties is used for numerical analysis. • Heat transfer and heat storage were analyzed in a fin-type heat exchanger. • Use of temperature-dependent properties in calculations lead to longer melting time. - Abstract: Temperature dependency of thermal diffusivity of erythritol was measured by temperature wave analysis (TWA) method. This modulating technique allowed measuring thermal diffusivity continuously, even during the phase transition solid-liquid. Together with specific heat capacity and specific enthalpy measured by differential scanning calorimetry, the values of measured properties were utilized in a bi-dimensional numerical model for analysis of heat transfer and heat storage performance. The geometry of the model is representative of a cross section of a fin-type heat exchanger, in which erythritol is filling the interspaces between fins. Time-dependent temperature change and heat storage performance were analyzed by considering the variation of thermophysical properties as a function of temperature. The numerical method can be utilized for a fast parametric analysis of heat transfer and heat storage performance into heat storage systems of phase-change materials and composites.
Numerical Study of Concentration Characteristics of Linear Fresnel Reflector System
International Nuclear Information System (INIS)
Lee, Hyun Jin; Kim, Jong Kyu; Lee, Sang Nam
2015-01-01
In this study, we numerically investigated the concentration characteristics of a linear Fresnel reflector system that can drive a solar thermal absorption refrigeration system to be installed in Saudi Arabia. Using an optical modeling program based on the Monte Carlo ray-tracing method, we simulated the concentrated solar flux, concentration efficiency, and concentrated solar energy on four representative days of the year - the vernal equinox, summer solstice, autumnal equinox, and winter solstice. Except the winter solstice, the concentrations were approximately steady from 9 AM to 15 PM, and the concentration efficiencies exceed 70%. Moreover, the maximum solar flux around the solar receiver center changes only within the range of 13.0 - 14.6 kW/m 2 . When we investigated the effects of the receiver installation height, reflector width, and reflector gap, the optimal receiver installation height was found to be 5 m. A smaller reflector width had a greater concentration efficiency. However, the design of the reflector width should be based on the capacity of the refrigeration system because it dominantly affects the concentrated solar energy. The present study was an essential prerequisite for thermal analyses of the solar receiver. Thus, an optical-thermal integration study in the future will assist with the performance prediction and design of the entire system
Numerical Study of Concentration Characteristics of Linear Fresnel Reflector System
Energy Technology Data Exchange (ETDEWEB)
Lee, Hyun Jin [Kookmin Univ., Seoul (Korea, Republic of); Kim, Jong Kyu; Lee, Sang Nam [Korea Institute of Energy Research, Daejeon (Korea, Republic of)
2015-12-15
In this study, we numerically investigated the concentration characteristics of a linear Fresnel reflector system that can drive a solar thermal absorption refrigeration system to be installed in Saudi Arabia. Using an optical modeling program based on the Monte Carlo ray-tracing method, we simulated the concentrated solar flux, concentration efficiency, and concentrated solar energy on four representative days of the year - the vernal equinox, summer solstice, autumnal equinox, and winter solstice. Except the winter solstice, the concentrations were approximately steady from 9 AM to 15 PM, and the concentration efficiencies exceed 70%. Moreover, the maximum solar flux around the solar receiver center changes only within the range of 13.0 - 14.6 kW/m{sup 2}. When we investigated the effects of the receiver installation height, reflector width, and reflector gap, the optimal receiver installation height was found to be 5 m. A smaller reflector width had a greater concentration efficiency. However, the design of the reflector width should be based on the capacity of the refrigeration system because it dominantly affects the concentrated solar energy. The present study was an essential prerequisite for thermal analyses of the solar receiver. Thus, an optical-thermal integration study in the future will assist with the performance prediction and design of the entire system.
Numerical approaches to complex quantum, semiclassical and classical systems
Energy Technology Data Exchange (ETDEWEB)
Schubert, Gerald
2008-11-03
In this work we analyse the capabilities of several numerical techniques for the description of different physical systems. Thereby, the considered systems range from quantum over semiclassical to classical and from few- to many-particle systems. In chapter 1 we investigate the behaviour of a single quantum particle in the presence of an external disordered background (static potentials). Starting from the quantum percolation problem, we address the fundamental question of a disorder induced (Anderson-) transition from extended to localised single-particle eigenstates. Distinguishing isolating from conducting states by applying a local distribution approach for the local density of states (LDOS), we detect the quantum percolation threshold in two- and three-dimensions. Extending the quantum percolation model to a quantum random resistor model, we comment on the possible relevance of our results to the influence of disorder on the conductivity in graphene sheets. For the calculation of the LDOS as well as for the Chebyshev expansion of the time evolution operator, the kernel polynomial method (KPM) is the key numerical technique. In chapter 2 we examine how a single quantum particle is influenced by retarded bosonic fields that are inherent to the system. Within the Holstein model, these bosonic degrees of freedom (phonons) give rise to an infinite dimensional Hilbert space, posing a true many-particle problem. Constituting a minimal model for polaron formation, the Holstein model allows us to study the optical absorption and activated transport in polaronic systems. Using a two-dimensional variant of the KPM, we calculate for the first time quasi-exactly the optical absorption and dc-conductivity as a function of temperature. In chapter 3 we come back to the time evolution of a quantum particle in an external, static potential and investigate the capability of semiclassical approximations to it. We address basic quantum effects as tunneling, interference and
Numerical approaches to complex quantum, semiclassical and classical systems
International Nuclear Information System (INIS)
Schubert, Gerald
2008-01-01
In this work we analyse the capabilities of several numerical techniques for the description of different physical systems. Thereby, the considered systems range from quantum over semiclassical to classical and from few- to many-particle systems. In chapter 1 we investigate the behaviour of a single quantum particle in the presence of an external disordered background (static potentials). Starting from the quantum percolation problem, we address the fundamental question of a disorder induced (Anderson-) transition from extended to localised single-particle eigenstates. Distinguishing isolating from conducting states by applying a local distribution approach for the local density of states (LDOS), we detect the quantum percolation threshold in two- and three-dimensions. Extending the quantum percolation model to a quantum random resistor model, we comment on the possible relevance of our results to the influence of disorder on the conductivity in graphene sheets. For the calculation of the LDOS as well as for the Chebyshev expansion of the time evolution operator, the kernel polynomial method (KPM) is the key numerical technique. In chapter 2 we examine how a single quantum particle is influenced by retarded bosonic fields that are inherent to the system. Within the Holstein model, these bosonic degrees of freedom (phonons) give rise to an infinite dimensional Hilbert space, posing a true many-particle problem. Constituting a minimal model for polaron formation, the Holstein model allows us to study the optical absorption and activated transport in polaronic systems. Using a two-dimensional variant of the KPM, we calculate for the first time quasi-exactly the optical absorption and dc-conductivity as a function of temperature. In chapter 3 we come back to the time evolution of a quantum particle in an external, static potential and investigate the capability of semiclassical approximations to it. We address basic quantum effects as tunneling, interference and
Numerical FEM Analyses of primary coolant system at NPP Temelin
International Nuclear Information System (INIS)
Junek, L.; Slovacek, M.; Ruzek, L.; Moulis, P.
2003-01-01
The main goal of this paper is to inform about the beginning and first steps of implementation of an aging management system at the Temelin NPP. The aging management system is important not only for achieving the current safety level but also for reaching operational reliability of a production unit equipment above the life time assumed by the original design, typically over 40 years. A method to locate the most prominent degradation regions is described. A global shell model of the primary coolant system including all loops and their components - reactor pressure vessel (RPV), steam generator (SG), main coolant pump (MCP), pressurizer, feed water and steam pipelines system is presented. The results of stress-strain analysis on the measured service parameters base are given. Validation of the results is very important and the method to compare the service measurement data with the numerical results is described. The global/local approach is mentioned and discussed. The effects of the complete global system on the individual components under monitoring are transformed into more accurate local spatial models. The local spatial models are used to analyze the gradual lifetime exhaustion of a facility during its service operation. Two spatial local models are presented, viz. feed water nozzle of SG and main coolant piping system T-brunch. The results of analysis of the local spatial models are processed by the neural network computing method, which is also described. The actual gradual damage of the material of the components under monitoring can be obtained based on the analyses performed and on the results from the neural network in combination with the knowledge of the real material characteristics. The procedures applied are included in the DIALIFE diagnostic system
Valx: A System for Extracting and Structuring Numeric Lab Test Comparison Statements from Text.
Hao, Tianyong; Liu, Hongfang; Weng, Chunhua
2016-05-17
To develop an automated method for extracting and structuring numeric lab test comparison statements from text and evaluate the method using clinical trial eligibility criteria text. Leveraging semantic knowledge from the Unified Medical Language System (UMLS) and domain knowledge acquired from the Internet, Valx takes seven steps to extract and normalize numeric lab test expressions: 1) text preprocessing, 2) numeric, unit, and comparison operator extraction, 3) variable identification using hybrid knowledge, 4) variable - numeric association, 5) context-based association filtering, 6) measurement unit normalization, and 7) heuristic rule-based comparison statements verification. Our reference standard was the consensus-based annotation among three raters for all comparison statements for two variables, i.e., HbA1c and glucose, identified from all of Type 1 and Type 2 diabetes trials in ClinicalTrials.gov. The precision, recall, and F-measure for structuring HbA1c comparison statements were 99.6%, 98.1%, 98.8% for Type 1 diabetes trials, and 98.8%, 96.9%, 97.8% for Type 2 diabetes trials, respectively. The precision, recall, and F-measure for structuring glucose comparison statements were 97.3%, 94.8%, 96.1% for Type 1 diabetes trials, and 92.3%, 92.3%, 92.3% for Type 2 diabetes trials, respectively. Valx is effective at extracting and structuring free-text lab test comparison statements in clinical trial summaries. Future studies are warranted to test its generalizability beyond eligibility criteria text. The open-source Valx enables its further evaluation and continued improvement among the collaborative scientific community.
Upscaling of permeability field of fractured rock system: Numerical examples
Bao, K.; Salama, Amgad; Sun, S.
2012-01-01
When the permeability field of a given porous medium domain is heterogeneous by the existence of randomly distributed fractures such that numerical investigation becomes cumbersome, another level of upscaling may be required. That is such complex permeability field could be relaxed (i.e., smoothed) by constructing an effective permeability field. The effective permeability field is an approximation to the real permeability field that preserves certain quantities and provides an overall acceptable description of the flow field. In this work, the effective permeability for a fractured rock system is obtained for different coarsening scenarios starting from very coarse mesh all the way towards the fine mesh simulation. In all these scenarios, the effective permeability as well as the pressure at each cell is obtained. The total flux at the exit boundary is calculated in all these cases, and very good agreement is obtained.
Numerical study on oil supply system of a rotary compressor
International Nuclear Information System (INIS)
Wu, Jianhua; Wang, Gang
2013-01-01
The oil supply system is a crucial reliability issue for rotary compressors. This paper provides a general method for analyzing the oil supply system of a rotary compressor by using computational fluid dynamics (CFD). The process includes establishing the physical model, dividing computational grid, setting boundary conditions, calculating leakage rates through the roller end clearances, translating the dynamic issue into the static issue and so on. Validation of the rationality of the oil supply system model has been made by the measurement of the main bearing oil flow rates. The effects of operating conditions of the compressor, the oil level height of the oil sump and the main design parameters of the oil supply system on the oil supply characteristics are analyzed by numerical simulation. It is found that the main bearing oil flow rate varies circularly along with the rotation of the shaft. The shape and inclination angle of the spiral groove also influence the main bearing oil flow rate. The oil leakage rates through the roller end clearances depend largely on the operating conditions. In addition, the oil level height of the oil sump has a huge effect on the total oil flow rate. -- Highlights: • A CFD method for analyzing the oil supply system of rotary compressor is presented. • Leakage through the roller end clearances depends on the operating condition. • Groove shape and inclination angle are the main design parameters of spiral grooves. • A parabolic interface of oil and gas can be formed in the gallery of the shaft. • Single-flow model and steady solver can be applied to the oil supply system
Numerical investigation of spray combustion in jet mixing type combustor for low NOx emission
International Nuclear Information System (INIS)
Watanabe, Hirotatsu; Suwa, Yoshikazu; Matsushita, Yohsuke; Morozumi, Yoshio; Aoki, Hideyuki; Tanno, Shoji; Miura, Takatoshi
2008-01-01
The present paper describes a numerical investigation of spray combustion in a jet mixing type combustor. In this combustor, kerosene spray was injected with a pressure atomizer, and high speed combustion air was introduced towards the spray flow through some inlet air nozzles to improve mixing of the spray and the air. In the numerical simulation, the conservative equations of mass, momentum and energy in the turbulent flow field were solved in conjunction with the k-ε two equation turbulence model. The effects of the diameter and the number of air inlet nozzles on the combustion behavior and NO emission were numerically investigated. When the diameter of the inlet air nozzle decreased from 8 to 4 mm, the calculated NO mole fraction in the exhaust gas was drastically decreased by about 80%. An increase in the inlet velocity resulted in improvement of the mixing of the spray and the air, and hence, the high temperature region where thermal NO was formed became narrow. As a result, the exhaust NO mole fraction decreased. Furthermore, a decrease in exhaust NO mole fraction was explained by a decrease in the residence time in the high temperature region above 1800 K
Numerical Analysis of a Passive Containment Filtered Venting System
International Nuclear Information System (INIS)
Kim, Taejoon; Ha, Huiun; Heo, Sun
2014-01-01
The passive Containment Filtered Venting system (CFVS) does not have principally any kind of isolation valves or filtering devices which need periodic maintenance. In this study, the hydro-thermal analysis is presented to investigate the existence of flow instability in the passive CFVS and its performance under the pressure change of APR+ containment building with LB-LOCA M/E data. The Passive Containment Filtered Venting System was suggested as a part in i-Power development project and the operation mechanism was investigated by numerical modeling and simulation using GOTHIC8.0 system code. There are four Phases for consideration to investigate the pressurization of the containment building, loss of hydrostatic head in the pipe line of CFVS, opening of pipe line and gas ejection to the coolant tank, and the head recovery inside the pipe as the containment gas exhausted. The simulation results show that gas generation rate determine the timing of head recovery in the CFVS pipe line and that the equipment of various devices inducing pressure loss at the pipe can give the capacity of Phase control of the passive CFVS operation
Numerical Analysis of Combined Well and Open-Closed Loops Geothermal (CWG) Systems
Park, Yu-Chul
2016-04-01
Open-loop geothermal heat pump (GHP) system and closed-loop heat pump systems have been used in Korea to reduce emission of greenhouse gases such as carbon dioxide (CO2). The GHP systems have the pros and cons, for example, the open-loop GHP system is good energy-efficient and the closed-loop GHP system requires minimum maintenance costs. The open-loop GHP system can be used practically only with large amount of groundwater supply. The closed-loop GHP system can be used with high costs of initial installation. The performance and efficiency of the GHP system depend on the characteristics of the GHP system itself in addition to the geologic conditions. To overcome the cons of open-loop or closed-loop GHP system, the combined well and open-closed loops geothermal (CWG) system was designed. The open-loop GHP system is surrounded with closed-loop GHP systems in the CWG system. The geothermal energy in closed-loop GHP systems is supplied by the groundwater pumped by the open-loop GHP system. In this study, 2 different types of the CWG systems (small aperture hybrid CWG system and large aperture CWG system) are estimated using numerical simulation models in the aspect of energy efficiency. This work was supported by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea. (No.20153030111120).
Asymptotic and numerical studies of a differential-delay system
Semak, Matthew Richard
A singularly-perturbed differential-delay equation is studied the form of which is seen in various fields. Relaxation effects are combined with nonlinear driving from the past in this system. Having an infinite dimensional phase space, this flow is capable of very interesting behavior. Among the rich aspects of the dynamics of such a relation, period doubling can be observed as parameters are varied. Rigorous proofs concerning the existence of such periodic solutions can be found in the literature. Attention is given to the (first) Hopf bifurcation as the periodic structure is born. Key questions concern the limit of fast relaxation. In this limit, one can analytically understand the development of the periodic solution in the neighborhood of the bifurcation along with the frequency shift which is encountered. This limit also reveals the underlying mapping structure present. In the model studied, this is the logistic map the behavior of which is well-known. Convergence of periodic solutions to the mapping's square wave involves central issues in this work. An analogue to Gibb's phenomenon presents itself as the mapping structure is approached for a certain range of parameters. Transition layers also exist and, together with the latter, present a challenge to various computational approaches. A highly accurate and efficient spectral numerical technique is introduced to properly resolve such behavior in the limit studied. This scheme is used to measure the period's dependence on the relaxation rate in this region of parameter space. Also, numerically assisted asymptotic analysis develops relations for the layers. Moreover, regimes of parameter values have been identified for which there exist extremely long-lived transient states of arbitrarily complex form. Finally, initial interval states are designed which lead to specific long-lived multi-layer patterns of significant complexity. Layer-layer interactions are considered concerning the formation and lifetime of
Numerical simulation of a three-stage stirling-type pulse-tube refrigerator
Energy Technology Data Exchange (ETDEWEB)
Etaati, M.A.
2011-06-22
The pulse-tube refrigerator (PTR) is a rather new device for cooling down to extremely low temperatures, i.e. below 4 K. The PTR works by the cyclic compression and expansion of helium that flows through a regenerator made of porous material, a cold heat exchanger, a tube, a hot heat exchanger and an orifice, in series. In a Stirling-type PTR compression and expansion are generated by a piston. The compression increases the temperature of the helium in the tube and makes it flow towards the orifice; the expansion decreases the temperature and makes the helium flow backwards to the regenerator. The net effect of warmer helium flowing in one direction and colder helium in the opposite direction is that of cooling power at the cold heat exchanger. Three PTRs are inter-connected aiming to obtain the desired 4 K lowest temperature. The conservation laws of mass, momentum and energy, and an equation of state, are simplified using asymptotic analysis based on low Mach-numbers. The regenerator is modelled one-dimensionally with Darcy's law for flow resistance. The tube is modelled either one-dimensionally without resistance or two-dimensionally with axisymmetric laminar viscous flow. The heat transfer in the porous medium of the regenerator and in the solid tube wall is taken into account. The gas can be either ideal or real. All the material properties, including viscosity and conductivity, are taken temperature and pressure dependent. Three single-stage PTRs are connected with the regenerators in series and the tubes in parallel and six flow possibilities at the junctions are considered. Three by-passes (double-inlets) are used to enhance and tune the performance. The governing equations are numerically solved with a finite-difference method of nominally second-order accuracy in space and time. Pressure correction, flux limiter, 1D-2D connections and domain decomposition are the keywords here. Special attention is paid to suitable initial conditions, high resolution
Numerical approaches to time evolution of complex quantum systems
International Nuclear Information System (INIS)
Fehske, Holger; Schleede, Jens; Schubert, Gerald; Wellein, Gerhard; Filinov, Vladimir S.; Bishop, Alan R.
2009-01-01
We examine several numerical techniques for the calculation of the dynamics of quantum systems. In particular, we single out an iterative method which is based on expanding the time evolution operator into a finite series of Chebyshev polynomials. The Chebyshev approach benefits from two advantages over the standard time-integration Crank-Nicholson scheme: speedup and efficiency. Potential competitors are semiclassical methods such as the Wigner-Moyal or quantum tomographic approaches. We outline the basic concepts of these techniques and benchmark their performance against the Chebyshev approach by monitoring the time evolution of a Gaussian wave packet in restricted one-dimensional (1D) geometries. Thereby the focus is on tunnelling processes and the motion in anharmonic potentials. Finally we apply the prominent Chebyshev technique to two highly non-trivial problems of current interest: (i) the injection of a particle in a disordered 2D graphene nanoribbon and (ii) the spatiotemporal evolution of polaron states in finite quantum systems. Here, depending on the disorder/electron-phonon coupling strength and the device dimensions, we observe transmission or localisation of the matter wave.
Numerical investigation into the existence of limit cycles in two-dimensional predator�prey systems
Directory of Open Access Journals (Sweden)
Quay van der Hoff
2013-05-01
Full Text Available There has been a surge of interest in developing and analysing models of interacting species in ecosystems, with specific interest in investigating the existence of limit cycles in systems describing the dynamics of these species. The original Lotka–Volterra model does not possess any limit cycles. In recent years this model has been modified to take disturbances into consideration and allow populations to return to their original numbers. By introducing logistic growth and a Holling Type II functional response to the traditional Lotka–Volterra-type models, it has been proven analytically that a unique, stable limit cycle exists. These proofs make use of Dulac functions, Liénard equations and invariant regions, relying on theory developed by Poincaré, Poincaré-Bendixson, Dulac and Liénard, and are generally perceived as difficult. Computer algebra systems are ideally suited to apply numerical methods to confirm or refute the analytical findings with respect to the existence of limit cycles in non-linear systems. In this paper a class of predator–prey models of a Gause type is used as the vehicle to illustrate the use of a simple, yet novel numerical algorithm. This algorithm confirms graphically the existence of at least one limit cycle that has analytically been proven to exist. Furthermore, adapted versions of the proposed algorithm may be applied to dynamic systems where it is difficult, if not impossible, to prove analytically the existence of limit cycles.
Numerical solutions of a ODE's system for neutronics
International Nuclear Information System (INIS)
Lima, Suzylaine da Silva; Ramos, Alexandre F.
2017-01-01
The preliminary results that were obtained in the computational implementation to solve numerically a System of Coupled Differential Equations were presented. This system is intended to describe the kinetics of nuclear reactions occurring in the interior of a fusion-fission hybrid reactor in which fusion occurs in periodic pulses, which may be laser, for example. The hybrid reactor contains a core in which the nuclear fusion fuel is injected and is enveloped by two layers both composed of subcritical fission fuel. Our results show that a fusion-fission hybrid reactor composed of two layers of fission can maximize the energy utilization in this type of reactor
Barker, Blake; Jung, Soyeun; Zumbrun, Kevin
2018-03-01
Turing patterns on unbounded domains have been widely studied in systems of reaction-diffusion equations. However, up to now, they have not been studied for systems of conservation laws. Here, we (i) derive conditions for Turing instability in conservation laws and (ii) use these conditions to find families of periodic solutions bifurcating from uniform states, numerically continuing these families into the large-amplitude regime. For the examples studied, numerical stability analysis suggests that stable periodic waves can emerge either from supercritical Turing bifurcations or, via secondary bifurcation as amplitude is increased, from subcritical Turing bifurcations. This answers in the affirmative a question of Oh-Zumbrun whether stable periodic solutions of conservation laws can occur. Determination of a full small-amplitude stability diagram - specifically, determination of rigorous Eckhaus-type stability conditions - remains an interesting open problem.
Numerical Simulations of Granular Physics in the Solar System
Ballouz, Ronald
2017-08-01
numerical results to laboratory experiments and observations by spacecraft we can begin to understand which microscopic properties (i.e., grain properties) control the macroscopic properties of the system. For example, we can compare the mechanical response of a spacecraft to landing or Cassini observations of Saturn's ring to understand how the penetration depth of a spacecraft or the complex optical depth structure of a ring system depends on the size and surface properties of the grains in those systems.
Numerical and algebraic studies for the control of finite-dimensional quantum systems
International Nuclear Information System (INIS)
Sander, Uwe
2010-01-01
In this thesis, two aspects of control theory, namely controllability and optimal control, are applied to quantum systems. The presented results are based on group theoretical techniques and numerical studies. By Lie-algebraic analysis, the controllability properties of systems with an arbitrary topology are described and related to the symmetries existing in these systems. We find that symmetry precludes full controllability. Our work investigates well-known control systems and gives rules for the design of new systems. Furthermore, theoretical and numerical concepts are instrumental to studying quantum channels: Their capacities are optimised using gradient flows on the unitary group in order to find counterexamples to a long-established additivity conjecture. The last part of this thesis presents and benchmarks a modular optimal control algorithm known as GRAPE. Numerical tests show how the interplay of its modules can be optimised for higher performance, and how the algorithm performs in comparison to a Krotov-type optimal control algorithm. It is found that GRAPE performs particularly well when aiming for high qualities. (orig.)
Numerical and algebraic studies for the control of finite-dimensional quantum systems
Energy Technology Data Exchange (ETDEWEB)
Sander, Uwe
2010-11-18
In this thesis, two aspects of control theory, namely controllability and optimal control, are applied to quantum systems. The presented results are based on group theoretical techniques and numerical studies. By Lie-algebraic analysis, the controllability properties of systems with an arbitrary topology are described and related to the symmetries existing in these systems. We find that symmetry precludes full controllability. Our work investigates well-known control systems and gives rules for the design of new systems. Furthermore, theoretical and numerical concepts are instrumental to studying quantum channels: Their capacities are optimised using gradient flows on the unitary group in order to find counterexamples to a long-established additivity conjecture. The last part of this thesis presents and benchmarks a modular optimal control algorithm known as GRAPE. Numerical tests show how the interplay of its modules can be optimised for higher performance, and how the algorithm performs in comparison to a Krotov-type optimal control algorithm. It is found that GRAPE performs particularly well when aiming for high qualities. (orig.)
Directory of Open Access Journals (Sweden)
Xiaozhou Hu
2017-01-01
Full Text Available The dynamic response of the deployment system while deploying a circular cylinder crossing wave surface and the following submerging process are investigated numerically. The present numerical approach is based on the combination of solution methods of cable dynamics and computational fluid dynamics (CFD. For the implementation of the numerical approach, a cosimulation platform based on a CFD code and MATLAB is developed to study the fluid-solid interaction problem in the process. To generate regular waves, a numerical wave tank is built based on a piston-type wave generation method and a wave damping method applying porous media. Numerical simulations are performed based on the cosimulation platform. The sensitivities of cable tension, velocity, and acceleration of deployed body to different input parameters are investigated, including phase angles, wave heights, and periods of regular waves and deploying velocities, and the effects of those input parameters on dynamic responses of the deployment system are also discussed.
Numerical Modelling of Sediment Transport in Combined Sewer Systems
DEFF Research Database (Denmark)
Schlütter, Flemming
A conceptual sediment transport model has been developed. Through a case study a comparison with other numerical models is performed.......A conceptual sediment transport model has been developed. Through a case study a comparison with other numerical models is performed....
Wecpos - Wave Energy Coastal Protection Oscillating System: A Numerical Assessment
Dentale, Fabio; Pugliese Carratelli, Eugenio; Rzzo, Gianfranco; Arsie, Ivan; Davide Russo, Salvatore
2010-05-01
In recent years, the interest in developing new technologies to produce energy with low environmental impact by using renewable sources has grown exponentially all over the world. In this context, the experiences made to derive electricity from the sea (currents, waves, etc.) are of particular interest. At the moment, due to the many existing experiments completed or still in progress, it is quite impossible explain what has been obtained but it is worth mentioning the EMEC, which summarizes the major projects in the world. Another important environmental aspect, also related to the maritime field, is the coastal protection from the sea waves. Even in this field, since many years, the structural and non-structural solutions which can counteract this phenomenon are analyzed, in order to cause the least possible damage to the environment. The studies in development by the researchers of the University of Salerno are based on these two aspect previously presented. Considering the technologies currently available, a submerged system has been designed, WECPOS (Wave Energy Coastal Protection Oscillating System), to be located on relatively shallow depths, to can be used simultaneously for both electricity generation and for the coastal protection using the oscillating motion of the water particles. The single element constituting the system is realized by a fixed base and three movable panels that can fluctuate in a fixed angle. The waves interact with the panels generating an alternative motion which can be exploited to produce electricity. At the same time, the constraint movement imposed for the rotation of the panels is a barrier to the wave propagation phenomena, triggering the breaking in the downstream part of the device. So the wave energy will be dissipated obtaining a positive effect for the coastal protection. Currently, the efficiency and effectiveness of the system (WECPOS single module) has been studied by using numerical models. Using the FLOW-3D
Alfonso, Lester; Zamora, Jose; Cruz, Pedro
2015-04-01
The stochastic approach to coagulation considers the coalescence process going in a system of a finite number of particles enclosed in a finite volume. Within this approach, the full description of the system can be obtained from the solution of the multivariate master equation, which models the evolution of the probability distribution of the state vector for the number of particles of a given mass. Unfortunately, due to its complexity, only limited results were obtained for certain type of kernels and monodisperse initial conditions. In this work, a novel numerical algorithm for the solution of the multivariate master equation for stochastic coalescence that works for any type of kernels and initial conditions is introduced. The performance of the method was checked by comparing the numerically calculated particle mass spectrum with analytical solutions obtained for the constant and sum kernels, with an excellent correspondence between the analytical and numerical solutions. In order to increase the speedup of the algorithm, software parallelization techniques with OpenMP standard were used, along with an implementation in order to take advantage of new accelerator technologies. Simulations results show an important speedup of the parallelized algorithms. This study was funded by a grant from Consejo Nacional de Ciencia y Tecnologia de Mexico SEP-CONACYT CB-131879. The authors also thanks LUFAC® Computacion SA de CV for CPU time and all the support provided.
User guide of AVS/ITBL for numerical environmental system
International Nuclear Information System (INIS)
Suzuki, Yoshio; Matsumoto, Nobuko; Yamagishi, Nobuhiro; Arakawa, Takuya; Kuraishi, Hideaki
2005-02-01
The Center for Promotion of Computational Science and Engineering of the Japan Atomic Energy Research Institute has carried out the ITBL (Information-Technology Based Laboratory) project which is one of e-Japan priority policy programs. The goal of the ITBL project is to create the vertical research environment in which intellectual resources such as remote computers, programs and data can be shared in Japanese research institutions and cooperative studies among researchers can be supported. AVS/ITBL is the visualization tool which has been developed aiming at realizing the efficient visualization in the ITBL environment. This visualization tool is one of the tools of ITBL infrastructure software and operates in cooperation with AVS/Express. Main functions of AVS/ITBL are as follows: it can directly read data files located on remote computers, it can display and control an image on the web browser, it can collaboratively display an image among remote researchers, and it can perform visualization process as a batch. In this paper, utilization of AVS/ITBL to the numerical environmental system, which is one of the applications in ITBL project, is presented. And the outline of the operation in this utilization is indicated. (author)
Numerical Simulation of a Solar Domestic Hot Water System
International Nuclear Information System (INIS)
Mongibello, L; Graditi, G; Bianco, N; Di Somma, M; Naso, V
2014-01-01
An innovative transient numerical model is presented for the simulation of a solar Domestic Hot Water (DHW) system. The solar collectors have been simulated by using a zerodimensional analytical model. The temperature distributions in the heat transfer fluid and in the water inside the tank have been evaluated by one-dimensional models. The reversion elimination algorithm has been used to include the effects of natural convection among the water layers at different heights in the tank on the thermal stratification. A finite difference implicit scheme has been implemented to solve the energy conservation equation in the coil heat exchanger, and the energy conservation equation in the tank has been solved by using the finite difference Euler implicit scheme. Energy conservation equations for the solar DHW components models have been coupled by means of a home-made implicit algorithm. Results of the simulation performed using as input data the experimental values of the ambient temperature and the solar irradiance in a summer day are presented and discussed
Numerical Simulation of a Solar Domestic Hot Water System
Mongibello, L.; Bianco, N.; Di Somma, M.; Graditi, G.; Naso, V.
2014-11-01
An innovative transient numerical model is presented for the simulation of a solar Domestic Hot Water (DHW) system. The solar collectors have been simulated by using a zerodimensional analytical model. The temperature distributions in the heat transfer fluid and in the water inside the tank have been evaluated by one-dimensional models. The reversion elimination algorithm has been used to include the effects of natural convection among the water layers at different heights in the tank on the thermal stratification. A finite difference implicit scheme has been implemented to solve the energy conservation equation in the coil heat exchanger, and the energy conservation equation in the tank has been solved by using the finite difference Euler implicit scheme. Energy conservation equations for the solar DHW components models have been coupled by means of a home-made implicit algorithm. Results of the simulation performed using as input data the experimental values of the ambient temperature and the solar irradiance in a summer day are presented and discussed.
Ambiguity in the m-bonacci numeration system
Directory of Open Access Journals (Sweden)
Petra Kocábová
2007-05-01
Full Text Available We study the properties of the function R (m (n defined as the number of representations of an integer n as a sum of distinct m-Bonacci numbers F (m k, given by F i (m =2 i-1, for i∈ { 1, 2, …, m}, F k+m (m =F k+m-1 (m +F k+m-2 (m + ⋯ + F k (m, for k ≥ 1. We give a matrix formula for calculating R (m (n from the greedy expansion of n. We determine the maximum of R (m (n for n with greedy expansion of fixed length k, i.e. for F (m k ≤ n
A numerical study on thermal behavior of a D-type water-cooled steam boiler
International Nuclear Information System (INIS)
Moghari, M.; Hosseini, S.; Shokouhmand, H.; Sharifi, H.; Izadpanah, S.
2012-01-01
To achieve a precise assessment on thermal performance of a D-type water-cooled natural gas-fired boiler the present paper was aimed at determining temperature distribution of water and flue gas flows in its different heat exchange equipment. Using the zonal method to predict thermal radiation treatment in the boiler furnace and a numerical iterative approach, in which heat and fluid flow relations associated with different heat surfaces in the boiler convective zone were employed to estimate heat transfer characteristics, enabled this numerical study to obtain results in good agreement with experimental data measured in the utility site during steady state operation. A constant flow rate for a natural gas fuel of specified chemical composition was assumed to be mixed with a given excess ratio of air flow at a full boiler load. Significant results attributed to distribution of heat flux on different furnace walls and that of flue gas and water/steam temperature in different convective stages including superheater, evaporating risers and downcomers modules, and economizer were obtained. Besides the rate of heat absorption in every stage and other essential parameters in the boiler design too, inherent thermal characteristics like radiative and convective heat transfer coefficients as well as overall heat transfer conductance and effectiveness of convective stages considered as cross-flow heat exchangers were eventually presented for the given operating condition. - Highlights: ► Detailed distribution of heat flux on all of the boiler furnace walls was obtained. ► Flue gas and water thermal behaviors in different heating sections were evaluated. ► A good agreement was made between numerical results and experimental data. ► Contribution of the boiler furnace to the total thermal absorption was 39%. ► Contribution of the boiler tube banks to the total thermal absorption was 61%.
A computable type theory for control systems
P.J. Collins (Pieter); L. Guo; J. Baillieul
2009-01-01
htmlabstractIn this paper, we develop a theory of computable types suitable for the study of control systems. The theory uses type-two effectivity as the underlying computational model, but we quickly develop a type system which can be manipulated abstractly, but for which all allowable operations
Numerical simulation of roadway support in a sandstone-type uranium mine
International Nuclear Information System (INIS)
Liu Huipeng; Li Yu; Song Lixia
2009-01-01
At present, the most surrounding rocks of sandstone-type uranium mines in China are mudstone, sandstone, pelitic siltstone, and so on. They show the characteristics of soft rock. Such uranium deposit is not fit for in-situ leaching. If the uranium ores are mined by conventional mining method, one of the problems to be solved is the support technique in the soft rock roadway. So, taking a uranium mine in Inner Mongolia as the research object, the support technique in the soft rock roadway of the sandstone-type uranium deposits is studied. Through on-site engineering geological investigation and laboratory test, the main reasons for roadway damage are analyzed. A technique of support in the soft rock roadway of sandstone-type uranium deposits is put forward by drawing on the expericnce of soft rock roadway support in coal mines. The roadway shape and support parameters are optimized by using a numerical simulation method. The results verified the feasibility of the supporting technique. (authors)
Numerical methods and applications in many fermion systems
Energy Technology Data Exchange (ETDEWEB)
Luitz, David J.
2013-02-07
This thesis presents results covering several topics in correlated many fermion systems. A Monte Carlo technique (CT-INT) that has been implemented, used and extended by the author is discussed in great detail in chapter 3. The following chapter discusses how CT-INT can be used to calculate the two particle Green's function and explains how exact frequency summations can be obtained. A benchmark against exact diagonalization is presented. The link to the dynamical cluster approximation is made in the end of chapter 4, where these techniques are of immense importance. In chapter 5 an extensive CT-INT study of a strongly correlated Josephson junction is shown. In particular, the signature of the first order quantum phase transition between a Kondo and a local moment regime in the Josephson current is discussed. The connection to an experimental system is made with great care by developing a parameter extraction strategy. As a final result, we show that it is possible to reproduce experimental data from a numerically exact CT-INT model-calculation. The last topic is a study of graphene edge magnetism. We introduce a general effective model for the edge states, incorporating a complicated interaction Hamiltonian and perform an exact diagonalization study for different parameter regimes. This yields a strong argument for the importance of forbidden umklapp processes and of the strongly momentum dependent interaction vertex for the formation of edge magnetism. Additional fragments concerning the use of a Legendre polynomial basis for the representation of the two particle Green's function, the analytic continuation of the self energy for the Anderson Kane Mele Model as well as the generation of test data with a given covariance matrix are documented in the appendix. A final appendix provides some very important matrix identities that are used for the discussion of technical details of CT-INT.
Numerical methods and applications in many fermion systems
International Nuclear Information System (INIS)
Luitz, David J.
2013-01-01
This thesis presents results covering several topics in correlated many fermion systems. A Monte Carlo technique (CT-INT) that has been implemented, used and extended by the author is discussed in great detail in chapter 3. The following chapter discusses how CT-INT can be used to calculate the two particle Green's function and explains how exact frequency summations can be obtained. A benchmark against exact diagonalization is presented. The link to the dynamical cluster approximation is made in the end of chapter 4, where these techniques are of immense importance. In chapter 5 an extensive CT-INT study of a strongly correlated Josephson junction is shown. In particular, the signature of the first order quantum phase transition between a Kondo and a local moment regime in the Josephson current is discussed. The connection to an experimental system is made with great care by developing a parameter extraction strategy. As a final result, we show that it is possible to reproduce experimental data from a numerically exact CT-INT model-calculation. The last topic is a study of graphene edge magnetism. We introduce a general effective model for the edge states, incorporating a complicated interaction Hamiltonian and perform an exact diagonalization study for different parameter regimes. This yields a strong argument for the importance of forbidden umklapp processes and of the strongly momentum dependent interaction vertex for the formation of edge magnetism. Additional fragments concerning the use of a Legendre polynomial basis for the representation of the two particle Green's function, the analytic continuation of the self energy for the Anderson Kane Mele Model as well as the generation of test data with a given covariance matrix are documented in the appendix. A final appendix provides some very important matrix identities that are used for the discussion of technical details of CT-INT.
International Nuclear Information System (INIS)
Xuelin, Tang Xue; Liyuan, Bian; Fujun, Wang; Xiaoqin, Lin; Man, Hao
2013-01-01
A cavitation model with thermodynamic effects for cavitating flows in a diffuser-type centrifugal pump is developed based on the bubble two-phase flow model. The proposed cavitation model includes mass, momentum, and energy transportations according to the thermodynamic mechanism of cavitation. Numerical simulations are conducted inside the entire passage of the centrifugal pump by using the proposed cavitation model and the renormalization group-based k - ε turbulent model coupled with the energy transportation equation. By using the commercial computational fluid dynamics software FLUENT 6.3, we have shown that the predicted performance characteristics of the pump, as well as the pressure, vapor, and density distributions in the impeller, agree well with that calculated by the full cavitation model. Simulation results show that cavitation initially occurs slightly behind the inlet of the blade suction surface, i.e., the area with maximum vapor concentration and minimum pressure. The predicted temperature field shows that the reduction in temperature restrains the growth of cavitating bubbles. Therefore, the thermodynamic effect should be treated as a necessary factor in cavitation models. Comparison results validate the efficiency and accuracy of the numerical technique in simulating cavitation flows in centrifugal pumps.
International Nuclear Information System (INIS)
Zheng, Wandong; Yang, Lin; Zhang, Huan; You, Shijun; Zhu, Chunguang
2016-01-01
Highlights: • A serpentine compound parabolic concentrator solar collector is proposed. • A mathematical model for the new collector is developed and verified by experiments. • The thermal efficiency of the collector can be up to 60.5% during the experiments. • The effects of key parameters on the thermal performance are mathematically studied. - Abstract: In order to improve the thermal efficiency, reduce the heat losses and achieve high freezing resistance of the solar device for space heating in cold regions, a new type of serpentine compound parabolic concentrator solar collector is presented in this paper, which is a combination of a compound parabolic concentrator solar collector and a flat plate solar collector. A detailed mathematical model for the new collector based on the analysis of heat transfer is developed and then solved by the software tool Matlab. The numerical results are compared with the experimental data and the maximum deviation is 8.07%, which shows a good agreement with each other. The experimental results show that the thermal efficiency of the collector can be as high as 60.5%. The model is used to predict the thermal performance of the new collector. The effects of structure and operating parameters on the thermal performance are mathematically discussed. The numerical and experimental results show that the new collector is more suitable to provide low temperature hot water for space heating in cold regions and the mathematical model will be much helpful in the designing and optimizing of the solar collectors.
International Nuclear Information System (INIS)
Barbieri, R.A.; Gastal, F.P.S.L.; Filho, A.C.
2005-01-01
Unbounded prestressed concrete has a growing importance all over the world and may be an useful technique for the structures involved in the construction of nuclear facilities. The absence of bonding means no strain compatibility so that equations developed for reinforced concrete are no longer valid. Practical estimates about the ultimate stress in the unbounded tendons may be obtained with empirical or numerical methods only. In order to contribute to the understanding on the behaviour of unbounded prestressed concrete members, a numerical model has been developed using a hybrid type finite element formulation for planar frame structures. Instead of short elements, as in the conventional finite element formulation, long elements may be used, improving computational efficiency. A further advantage is that the curvature variation within the element is obtained with higher accuracy if compared to the traditional formulation. This feature is important for unbounded tendons since its stresses depend on the whole member deformation. Second order effects in the planar frame are considered with either Updated or Partially Updated Lagrangian approaches. Instantaneous and time dependent behaviour as well as cyclic loads are considered too. Comparison with experimental results for prestressed concrete beams shows the adequacy of the proposed model. (authors)
Numerical simulations of type II gradient drift irregularities in the equatorial electrojet
International Nuclear Information System (INIS)
Ferch, R.L.; Sudan, R.N.
1977-01-01
Two-dimensional numerical studies of the development of type II irregularities in the equatorial electrojet have been carried out using a method similar to that of McDonald et al., (1974) except that ion inertia has been neglected. This simplification is shown to be a valid approximation whenever the electron drift velocity is small in comparison with the ion acoustic velocity and the values of the other parameters are those appropriate for the equatorial E layer. This code enables us to follow the development of quasi-steady state turbulence from appropriate initial pertubations. The two-dimensional turbulent spectrum of electron density perturbations excited is studied both for the case of devlopment from initial perturbations and for the case of a continuously pumped single driving wave
Directory of Open Access Journals (Sweden)
Ikuo Yamamoto
2017-10-01
Full Text Available The generation of clean renewable energy is becoming increasingly critical, as pollution and global warming threaten the environment in which we live. While there are many different kinds of natural energy that can be harnessed, marine tidal energy offers reliability and predictability. However, harnessing energy from tidal flows is inherently difficult, due to the harsh environment. Current mechanisms used to harness tidal flows center around propeller-based solutions but are particularly prone to failure due to marine fouling from such as encrustations and seaweed entanglement and the corrosion that naturally occurs in sea water. In order to efficiently harness tidal flow energy in a cost-efficient manner, development of a mechanism that is inherently resistant to these harsh conditions is required. One such mechanism is a simple oscillatory-type mechanism based on robotic fish tail fin technology. This uses the physical phenomenon of vortex-induced oscillation, in which water currents flowing around an object induce transverse motion. We consider two specific types of oscillators, firstly a wing-type oscillator, in which the optimal elastic modulus is being sort. Secondly, the optimal selection of shape from 6 basic shapes for a reciprocating oscillating head-type oscillator. A numerical analysis tool for fluid structure-coupled problems—ANSYS—was used to select the optimum softness of material for the first type of oscillator and the best shape for the second type of oscillator, based on the exhibition of high lift coefficients. For a wing-type oscillator, an optimum elastic modulus for an air-foil was found. For a self-induced vibration-type mechanism, based on analysis of vorticity and velocity distribution, a square-shaped head exhibited a lift coefficient of more than two times that of a cylindrically shaped head. Analysis of the flow field clearly showed that the discontinuous flow caused by a square-headed oscillator results in
Pshenichnikov, A F
2000-01-01
The Monte Carlo method is used to study the equilibrium magnetization of a 3D system of superparamagnetic particles taking into account the steric and dipole-dipole interparticle interactions. Two types of systems are considered: magnetic fluids and solidified ferrocolloids containing randomly spatially distributed particles with negligible energy of magnetic anisotropy. The results of numerical simulations confirm the universality of Langevin susceptibility as a main dimensionless parameter determining the influence of interparticle interactions on the magnetization of the system for moderate values of the aggregation parameter. The obtained results are in good agreement with theoretical and experimental data. At large values of the aggregation parameter, the clustering of particles in magnetic fluids is observed resulting in a reduction of their magnetization as compared to solidified systems. It is shown that the magnetization of solidified systems can be well described by the modified effective field appr...
International Nuclear Information System (INIS)
Pshenichnikov, A.F.; Mekhonoshin, V.V.
2000-01-01
The Monte Carlo method is used to study the equilibrium magnetization of a 3D system of superparamagnetic particles taking into account the steric and dipole-dipole interparticle interactions. Two types of systems are considered: magnetic fluids and solidified ferrocolloids containing randomly spatially distributed particles with negligible energy of magnetic anisotropy. The results of numerical simulations confirm the universality of Langevin susceptibility as a main dimensionless parameter determining the influence of interparticle interactions on the magnetization of the system for moderate values of the aggregation parameter. The obtained results are in good agreement with theoretical and experimental data. At large values of the aggregation parameter, the clustering of particles in magnetic fluids is observed resulting in a reduction of their magnetization as compared to solidified systems. It is shown that the magnetization of solidified systems can be well described by the modified effective field approximation within the whole investigated range of parameters
Numerical Propulsion System Simulation (NPSS): An Award Winning Propulsion System Simulation Tool
Stauber, Laurel J.; Naiman, Cynthia G.
2002-01-01
The Numerical Propulsion System Simulation (NPSS) is a full propulsion system simulation tool used by aerospace engineers to predict and analyze the aerothermodynamic behavior of commercial jet aircraft, military applications, and space transportation. The NPSS framework was developed to support aerospace, but other applications are already leveraging the initial capabilities, such as aviation safety, ground-based power, and alternative energy conversion devices such as fuel cells. By using the framework and developing the necessary components, future applications that NPSS could support include nuclear power, water treatment, biomedicine, chemical processing, and marine propulsion. NPSS will dramatically reduce the time, effort, and expense necessary to design and test jet engines. It accomplishes that by generating sophisticated computer simulations of an aerospace object or system, thus enabling engineers to "test" various design options without having to conduct costly, time-consuming real-life tests. The ultimate goal of NPSS is to create a numerical "test cell" that enables engineers to create complete engine simulations overnight on cost-effective computing platforms. Using NPSS, engine designers will be able to analyze different parts of the engine simultaneously, perform different types of analysis simultaneously (e.g., aerodynamic and structural), and perform analysis in a more efficient and less costly manner. NPSS will cut the development time of a new engine in half, from 10 years to 5 years. And NPSS will have a similar effect on the cost of development: new jet engines will cost about a billion dollars to develop rather than two billion. NPSS is also being applied to the development of space transportation technologies, and it is expected that similar efficiencies and cost savings will result. Advancements of NPSS in fiscal year 2001 included enhancing the NPSS Developer's Kit to easily integrate external components of varying fidelities, providing
Compactly Supported Curvelet-Type Systems
DEFF Research Database (Denmark)
Rasmussen, Kenneth Niemann; Nielsen, Morten
2012-01-01
We study a flexible method for constructing curvelet-type frames. These curvelet-type systems have the same sparse representation properties as curvelets for appropriate classes of smooth functions, and the flexibility of the method allows us to give a constructive description of how to construct...... curvelet-type systems with a prescribed nature such as compact support in direct space. The method consists of using the machinery of almost diagonal matrices to show that a system of curvelet molecules which is sufficiently close to curvelets constitutes a frame for curvelet-type spaces. Such a system...
Bender, Andrea; Schlimm, Dirk; Beller, Sieghard
2015-10-01
The domain of numbers provides a paradigmatic case for investigating interactions of culture, language, and cognition: Numerical competencies are considered a core domain of knowledge, and yet the development of specifically human abilities presupposes cultural and linguistic input by way of counting sequences. These sequences constitute systems with distinct structural properties, the cross-linguistic variability of which has implications for number representation and processing. Such representational effects are scrutinized for two types of verbal numeration systems-general and object-specific ones-that were in parallel use in several Oceanic languages (English with its general system is included for comparison). The analysis indicates that the object-specific systems outperform the general systems with respect to counting and mental arithmetic, largely due to their regular and more compact representation. What these findings reveal on cognitive diversity, how the conjectures involved speak to more general issues in cognitive science, and how the approach taken here might help to bridge the gap between anthropology and other cognitive sciences is discussed in the conclusion. Copyright © 2015 Cognitive Science Society, Inc.
Spectrophotometry of VV Cephei-type systems
International Nuclear Information System (INIS)
Piccirillo, J.
1974-01-01
Photoelectric spectrophotometry of four VV Cephei-type systems and two related objects is analyzed to derive the visual magnitude differences of the binary components. The results are in good agreement with previous photometric determinations. An extension of the present technique to other types of binary systems is briefly discussed. (U.S.)
HLA typing in systemic sclerosis
Directory of Open Access Journals (Sweden)
M. Faré
2011-09-01
Full Text Available Objective: the aim of the study was to investigate the relationship between Systemic Sclerosis (SSc and HLA antigens, and to correlate these antigens with the clinical manifestations of the disease. Materials and methods: 55 patients were stratified according a to the cutaneous involvement b to the positivity of Scl- 70 and anticentromere antibody and c to the internal organ involvement, in particular we used HRCT to demonstrate lung fibrosis, echocardiography for the diagnosis of pulmonary hypertension, blood creatinine, urinalysis and arterial hypertension to demonstrate renal failure, and esophagus double-countrast barium swallow for the diagnosis of esophagopathy. The control group consisting of 2000 healthy Caucasian subjects was recruited from the same population. Results: the frequency of the antigens A23 (p=0.003, RR=3.69, B18 (p<0.0001, RR=3.57, and DR11 (p<0.0001, RR=6.18 was statistically increased in the patients population compared with the healthy controls. Although there is no any significant correlation between HLA antigens and different clinical subsets of scleroderma, antigens B18 and DR11 could be associated with more severe clinical features. Conclusions: the presence of a significant association between SSc and specific HLA antigens (A23, B18, and DR11 could link the HLA system with SSc.
Impact-friction vibrations of tubular systems. Numerical simulation and experimental validation
International Nuclear Information System (INIS)
Jacquart, G.
1993-05-01
This note presents a summary on the numerical developments made to simulate impact-friction vibrations of tubular systems, detailing the algorithms used and the expression of impact and friction forces. A synthesis of the experimental results obtained on MASSIF workbench is also presented, as well as their comparison with numerical computations in order to validate the numerical approach. (author). 5 refs
Zhao, WenHua; Yang, JianMin; Hu, ZhiQiang; Xiao, LongFei; Peng, Tao
2013-03-01
The present paper does an experimental and numerical investigation of the hydrodynamic interaction and the response of a single point turret-moored Floating Liquefied Natural Gas (FLNG) system, which is a new type of floating LNG (Liquid Natural Gas) platform that consists of a ship-type FPSO hull equipped with LNG storage tanks and liquefaction plants. In particular, this study focuses on the investigation of the roll response of FLNG hull in free-decay motions, white noise waves and also in irregular waves. Model tests of the FLNG system in 60%H filling condition excited by both white noise waves and irregular waves combined with steady wind and current have been carried out. Response Amplitude Operators (RAOs) and time histories of the responses are obtained for sway, roll and yaw motions. Obvious Low Frequency (LF) components of the roll motions are observed, which may be out of expectation. To facilitate the physical understanding of this phenomenon, we filter the roll motions at the period of 30 s into two parts: the Wave Frequency (WF) motions and the Low Frequency (LF) motions respectively. The results indicate that the LF motions are closely related to the sway and yaw motions. Possible reasons for the presence of the LF motions of roll have been discussed in detail, through the comparison with the sway and yaw motions. As for the numerical part, the simulation of the modeled case is conducted with the help of the software SESAM®. A good agreement between experiments and calculations is reported within the scope of trends. However, the numerical simulations should be further improved for the prediction of the FLNG system in the heading sea.
International Nuclear Information System (INIS)
Nykyri, Mikko
1987-05-01
The aim of the work is to model experimentally the inner structures and materials of two reactor waste repositories and to use the results for the validation work of a numerical near field release model, REPCOM. The experimental modelling of the multibarrier systems is conducted on a laboratory scale by using the same principal materials as are employed in the Finnish reactor waste disposal concepts. The migration of radionuclides is studied in two or more consecutive material layers. The laboratory arrangements include the following test materials: bituminized resin, cemented resin, concrete, crushed rock, and water. The materials correspond to the local materials in the planned disposal systems. Cs-137, Co-60, Sr-85, and Sr-90 are used as tracers, with which the resin, water, and crushed rock are labeled depending on the specimen type. The basic specimen geometries are cylindrical and cubic. In the cylindrical geometry the test materials were placed into PVC-tubes. The corresponding numerical model is one-dimensional. In the cubic geometry the materials were placed inside each other. The boundaries form cubes, and the numerical model is three-dimensional. Altogether 12 test system types were produced. The gamma active nuclides in the cylindrical samples were measured nondestructively with a scanner in order to determine the activity profiles in the specimens. The gamma active nuclides in the cubic samples and the beta emeitting Sr-90 in separate samples will be measured after splitting the samples. One to five activity profiles were determined for each cylindrical gamma-active sample. There are already clear diffusion profiles to be had for strontium in crushed rock, and for cesium in crushed rock and in concrete. Cobalt indicated no diffusion. No activity profiles were measured for the cubic samples or for the beta active, Sr-90-doped samples
A model selection support system for numerical simulations of nuclear thermal-hydraulics
International Nuclear Information System (INIS)
Gofuku, Akio; Shimizu, Kenji; Sugano, Keiji; Yoshikawa, Hidekazu; Wakabayashi, Jiro
1990-01-01
In order to execute efficiently a dynamic simulation of a large-scaled engineering system such as a nuclear power plant, it is necessary to develop intelligent simulation support system for all phases of the simulation. This study is concerned with the intelligent support for the program development phase and is engaged in the adequate model selection support method by applying AI (Artificial Intelligence) techniques to execute a simulation consistent with its purpose and conditions. A proto-type expert system to support the model selection for numerical simulations of nuclear thermal-hydraulics in the case of cold leg small break loss-of-coolant accident of PWR plant is now under development on a personal computer. The steps to support the selection of both fluid model and constitutive equations for the drift flux model have been developed. Several cases of model selection were carried out and reasonable model selection results were obtained. (author)
Theoretical Hill-type muscle and stability: numerical model and application.
Schmitt, S; Günther, M; Rupp, T; Bayer, A; Häufle, D
2013-01-01
The construction of artificial muscles is one of the most challenging developments in today's biomedical science. The application of artificial muscles is focused both on the construction of orthotics and prosthetics for rehabilitation and prevention purposes and on building humanoid walking machines for robotics research. Research in biomechanics tries to explain the functioning and design of real biological muscles and therefore lays the fundament for the development of functional artificial muscles. Recently, the hyperbolic Hill-type force-velocity relation was derived from simple mechanical components. In this contribution, this theoretical yet biomechanical model is transferred to a numerical model and applied for presenting a proof-of-concept of a functional artificial muscle. Additionally, this validated theoretical model is used to determine force-velocity relations of different animal species that are based on the literature data from biological experiments. Moreover, it is shown that an antagonistic muscle actuator can help in stabilising a single inverted pendulum model in favour of a control approach using a linear torque generator.
Energy Technology Data Exchange (ETDEWEB)
Shin, Young Kil [Dept. of Electircal Engineeirng, Kunsan National University, Kunsan (Korea, Republic of)
2013-12-15
An encircling send-receive type pulsed eddy current (PEC) probe is designed for use in aluminum tube inspection. When bare receive coils located away from the exciter were used, the peak time of the signal did not change although the distance from the exciter increased. This is because the magnetic flux from the exciter coil directly affects the receive coil signal. Therefore, in this work, both the exciter and the sensor coils were shielded in order to reduce the influence of direct flux from the exciter coil. Numerical simulation with the designed shielded encircling PEC probe showed the corresponding increase of the peak time as the sensor distance increased. Ferrite and carbon steel shields were compared and results of the ferrite shielding showed a slightly stronger peak value and a quicker peak time than those of the carbon steel shielding. Simulation results showed that the peak value increased as the defect size (such as depth and length) increased regardless of the sensor location. To decide a proper sensor location, the sensitivity of the peak value to defect size variation was investigated and found that the normalized peak value was more sensitive to defect size variation when the sensor was located closer to the exciter.
Numerical solution of multiband k.p model for tunnelling in type-II heterostructures
Directory of Open Access Journals (Sweden)
A.E. Botha
2010-01-01
Full Text Available A new and very general method was developed for calculating the charge and spin-resolved electron tunnelling in type-II heterojunctions. Starting from a multiband k.p description of the bulk energy-band structure, a multiband k.p Riccati equation was derived. The reflection and transmission coefficients were obtained for each channel by integrating the Riccati equation over the entire heterostructure. Numerical instability was reduced through this method, in which the multichannel log-derivative of the envelope function matrix, rather than the envelope function itself, was propagated. As an example, a six-band k.p Hamiltonian was used to calculate the current-voltage characteristics of a 10-nm wide InAs/ GaSb/InAs single quantum well device which exhibited negative differential resistance at room temperature. The calculated current as a function of applied (bias voltage was found to be in semiquantitative agreement with the experiment, a result which indicated that inelastic transport mechanisms do not contribute significantly to the valley currents measured in this particular device.
Directory of Open Access Journals (Sweden)
Zhenkun Sang
2018-04-01
Full Text Available Ultra-low calorific value gas (ULCVG not only poses a problem for environmental pollution, but also createsa waste of energy resources if not utilized. A novel reactor, a rotary regenerator-type catalytic combustion reactor (RRCCR, which integrates the functions of a regenerator and combustor into one component, is proposed for the elimination and utilization of ULCVG. Compared to reversal-flow reactor, the operation of the RRCCR is achieved by incremental rotation rather than by valve control, and it has many outstanding characteristics, such as a compact structure, flexible application, and limited energy for circulation. Due to the effects of the variation of the gas flow and concentration on the performance of the reactor, different inlet velocities and concentrations are analyzed by numerical investigations. The results reveal that the two factors have a major impact on the performance of the reactor. The performance of the reactor is more sensitive to the increase of velocity and the decrease of methane concentration. When the inlet concentration (2%vol. is reduced by 50%, to maintain the methane conversion over 90%, the inlet velocity can be reduced by more than three times. Finally, the highly-efficient and stable operating envelope of the reactor is drawn.
Theoretical Hill-Type Muscle and Stability: Numerical Model and Application
Directory of Open Access Journals (Sweden)
S. Schmitt
2013-01-01
Full Text Available The construction of artificial muscles is one of the most challenging developments in today’s biomedical science. The application of artificial muscles is focused both on the construction of orthotics and prosthetics for rehabilitation and prevention purposes and on building humanoid walking machines for robotics research. Research in biomechanics tries to explain the functioning and design of real biological muscles and therefore lays the fundament for the development of functional artificial muscles. Recently, the hyperbolic Hill-type force-velocity relation was derived from simple mechanical components. In this contribution, this theoretical yet biomechanical model is transferred to a numerical model and applied for presenting a proof-of-concept of a functional artificial muscle. Additionally, this validated theoretical model is used to determine force-velocity relations of different animal species that are based on the literature data from biological experiments. Moreover, it is shown that an antagonistic muscle actuator can help in stabilising a single inverted pendulum model in favour of a control approach using a linear torque generator.
A Numerical Approach for Hybrid Simulation of Power System Dynamics Considering Extreme Icing Events
DEFF Research Database (Denmark)
Chen, Lizheng; Zhang, Hengxu; Wu, Qiuwei
2017-01-01
numerical simulation scheme integrating icing weather events with power system dynamics is proposed to extend power system numerical simulation. A technique is developed to efficiently simulate the interaction of slow dynamics of weather events and fast dynamics of power systems. An extended package for PSS...
Numerical simulation of nonlinear dynamical systems driven by commutative noise
International Nuclear Information System (INIS)
Carbonell, F.; Biscay, R.J.; Jimenez, J.C.; Cruz, H. de la
2007-01-01
The local linearization (LL) approach has become an effective technique for the numerical integration of ordinary, random and stochastic differential equations. One of the reasons for this success is that the LL method achieves a convenient trade-off between numerical stability and computational cost. Besides, the LL method reproduces well the dynamics of nonlinear equations for which other classical methods fail. However, in the stochastic case, most of the reported works has been focused in Stochastic Differential Equations (SDE) driven by additive noise. This limits the applicability of the LL method since there is a number of interesting dynamics observed in equations with multiplicative noise. On the other hand, recent results show that commutative noise SDEs can be transformed into a random differential equation (RDE) by means of a random diffeomorfism (conjugacy). This paper takes advantages of such conjugacy property and the LL approach for defining a LL scheme for SDEs driven by commutative noise. The performance of the proposed method is illustrated by means of numerical simulations
Numerical fluid flow and heat transfer calculations on multiprocessor systems
Energy Technology Data Exchange (ETDEWEB)
Oehman, G.A.; Malen, T.E.; Kuusela, P.
1989-01-01
The first part of the report presents the basic principles of parallel processing, and factors influencing tbe efficiency of practical applications are discussed. In a multiprocessor computer, different parts of the program code are executed in parallel, i.e. simultaneous with respect to time, on different processors, and thus it becomes possible to decrease the overall computation time by a factor, which in the ideal case is equal to the number of processors. The application study starts from the numerical solution of the twodimesional Laplace equation, which describes the steady heat conduction in a solid plate and advances through the solution of the three dimensional Laplace equation to the case of study laminar fluid flow in a twodimensional box at Reynolds numbers up to 20. Hereby the stream function-vorticity method is first applied and the SIMPLER method. The conventional (sequential) numerical algoritms for these fluid flow and heat transfer problems are found not to be ideally suited for conversion to parallel computation, but sped-up ratios considerably above 50 % of the theoretical maximum are regularly achieved in the runs. The numerical procedures we coded in the OCCAM-2 language and the test runs were performed at who Akademi on the imperimental HATHI-computers containing 16 T4l4 and 100 INMOS T800 transputers respectively.
Numerical fluid flow and heat transfer calculations on multiprocessor systems
Energy Technology Data Exchange (ETDEWEB)
Oehman, G.A.; Malen, T.E.; Kuusela, P.
1989-12-31
The first part of the report presents the basic principles of parallel processing, and factors influencing tbe efficiency of practical applications are discussed. In a multiprocessor computer, different parts of the program code are executed in parallel, i.e. simultaneous with respect to time, on different processors, and thus it becomes possible to decrease the overall computation time by a factor, which in the ideal case is equal to the number of processors. The application study starts from the numerical solution of the twodimesional Laplace equation, which describes the steady heat conduction in a solid plate and advances through the solution of the three dimensional Laplace equation to the case of study laminar fluid flow in a twodimensional box at Reynolds numbers up to 20. Hereby the stream function-vorticity method is first applied and the SIMPLER method. The conventional (sequential) numerical algoritms for these fluid flow and heat transfer problems are found not to be ideally suited for conversion to parallel computation, but sped-up ratios considerably above 50 % of the theoretical maximum are regularly achieved in the runs. The numerical procedures we coded in the OCCAM-2 language and the test runs were performed at who Akademi on the imperimental HATHI-computers containing 16 T4l4 and 100 INMOS T800 transputers respectively.
Fazio, Lisa K.; Bailey, Drew H.; Thompson, Clarissa A.; Siegler, Robert S.
2014-01-01
We examined relations between symbolic and non-symbolic numerical magnitude representations, between whole number and fraction representations, and between these representations and overall mathematics achievement in fifth graders. Fraction and whole number symbolic and non-symbolic numerical magnitude understandings were measured using both…
Automated Testcase Generation for Numerical Support Functions in Embedded Systems
Schumann, Johann; Schnieder, Stefan-Alexander
2014-01-01
We present a tool for the automatic generation of test stimuli for small numerical support functions, e.g., code for trigonometric functions, quaternions, filters, or table lookup. Our tool is based on KLEE to produce a set of test stimuli for full path coverage. We use a method of iterative deepening over abstractions to deal with floating-point values. During actual testing the stimuli exercise the code against a reference implementation. We illustrate our approach with results of experiments with low-level trigonometric functions, interpolation routines, and mathematical support functions from an open source UAS autopilot.
Formal languages, automata and numeration systems introduction to combinatorics on words
Rigo, Michel
2014-01-01
Formal Languages, Automaton and Numeration Systems presents readers with a review of research related to formal language theory, combinatorics on words or numeration systems, such as Words, DLT (Developments in Language Theory), ICALP, MFCS (Mathematical Foundation of Computer Science), Mons Theoretical Computer Science Days, Numeration, CANT (Combinatorics, Automata and Number Theory). Combinatorics on words deals with problems that can be stated in a non-commutative monoid, such as subword complexity of finite or infinite words, construction and properties of infinite words, unavoidabl
A numerical study of scale effects on performance of a tractor type podded propeller
Directory of Open Access Journals (Sweden)
Choi Jung-Kyu
2014-06-01
Full Text Available In this study, the scale effect on the performance of the podded propeller of tractor type is investigated. Turbulent flow computations are carried out for Reynolds numbers increasing progressively from model scale to full scale using the CFD analysis. The result of the flow calculation for model scale Reynolds numbers agrees well with that of the experiment of a large cavitation tunnel. The existing numerical analysis indicates that the performance of the podded propeller blades is mainly influenced by the advance coefficient and relatively little by the Reynolds number. However, the drag of pod housing with propeller in operation is different from that of pod housing without propeller due to the acceleration and swirl of propeller slipstream which is altered by propeller loading as well as the pressure recovery and friction according to Reynolds number, which suggests that the pod housing drag under the condition of propeller in operation is the key factor of the scale effect on the performance between model and full scale podded propellers. The so called ‘drag ratio’, which is the ratio of pod housing drag to total thrust of podded propeller, increases as the advance coefficient increases due to accelerated flow in the slipstream of the podded propeller. However, the increasing rate of the drag ratio reduces continuously as the Reynolds number increases from model to full scale progressively. The contribution of hydrodynamic forces, which acts on the parts composed of the pod housing with propeller operating in various loading conditions, to the thrust and the torque of the total propeller unit are presented for a range of Reynolds numbers from model to full scales.
Numerical analysis for finite-range multitype stochastic contact financial market dynamic systems
International Nuclear Information System (INIS)
Yang, Ge; Wang, Jun; Fang, Wen
2015-01-01
In an attempt to reproduce and study the dynamics of financial markets, a random agent-based financial price model is developed and investigated by the finite-range multitype contact dynamic system, in which the interaction and dispersal of different types of investment attitudes in a stock market are imitated by viruses spreading. With different parameters of birth rates and finite-range, the normalized return series are simulated by Monte Carlo simulation method and numerical studied by power-law distribution analysis and autocorrelation analysis. To better understand the nonlinear dynamics of the return series, a q-order autocorrelation function and a multi-autocorrelation function are also defined in this work. The comparisons of statistical behaviors of return series from the agent-based model and the daily historical market returns of Shanghai Composite Index and Shenzhen Component Index indicate that the proposed model is a reasonable qualitative explanation for the price formation process of stock market systems
Numerical analysis for finite-range multitype stochastic contact financial market dynamic systems
Yang, Ge; Wang, Jun; Fang, Wen
2015-04-01
In an attempt to reproduce and study the dynamics of financial markets, a random agent-based financial price model is developed and investigated by the finite-range multitype contact dynamic system, in which the interaction and dispersal of different types of investment attitudes in a stock market are imitated by viruses spreading. With different parameters of birth rates and finite-range, the normalized return series are simulated by Monte Carlo simulation method and numerical studied by power-law distribution analysis and autocorrelation analysis. To better understand the nonlinear dynamics of the return series, a q-order autocorrelation function and a multi-autocorrelation function are also defined in this work. The comparisons of statistical behaviors of return series from the agent-based model and the daily historical market returns of Shanghai Composite Index and Shenzhen Component Index indicate that the proposed model is a reasonable qualitative explanation for the price formation process of stock market systems.
Directory of Open Access Journals (Sweden)
S. P. Lakshmanan
2010-01-01
Full Text Available The behaviour of a parallel-channel natural circulation boiling water reactor under a low-pressure low-power startup condition has been studied numerically (using RELAP5 and compared with its scaled model. The parallel-channel RELAP5 model is an extension of a single-channel model developed and validated with experimental results. Existence of in-phase and out-of-phase flashing instabilities in the parallel-channel systems is investigated through simulations under equal and unequal power boundary conditions in the channels. The effect of flow resistance on Type-I oscillations is explored. For nonidentical condition in the channels, the flow fluctuations in the parallel-channel systems are found to be out-of-phase.
Numerical analysis for finite-range multitype stochastic contact financial market dynamic systems
Energy Technology Data Exchange (ETDEWEB)
Yang, Ge; Wang, Jun [School of Science, Beijing Jiaotong University, Beijing 100044 (China); Fang, Wen, E-mail: fangwen@bjtu.edu.cn [School of Economics and Management, Beijing Jiaotong University, Beijing 100044 (China)
2015-04-15
In an attempt to reproduce and study the dynamics of financial markets, a random agent-based financial price model is developed and investigated by the finite-range multitype contact dynamic system, in which the interaction and dispersal of different types of investment attitudes in a stock market are imitated by viruses spreading. With different parameters of birth rates and finite-range, the normalized return series are simulated by Monte Carlo simulation method and numerical studied by power-law distribution analysis and autocorrelation analysis. To better understand the nonlinear dynamics of the return series, a q-order autocorrelation function and a multi-autocorrelation function are also defined in this work. The comparisons of statistical behaviors of return series from the agent-based model and the daily historical market returns of Shanghai Composite Index and Shenzhen Component Index indicate that the proposed model is a reasonable qualitative explanation for the price formation process of stock market systems.
Energy Technology Data Exchange (ETDEWEB)
Lewin, M.
2009-06-15
This thesis is devoted to the mathematical study of variational models for large quantum systems. The mathematical methods are that of nonlinear analysis, calculus of variations, partial differential equations, spectral theory, and numerical analysis. The first part contains some results on finite systems. We study several approximations of the N-body Schroedinger equation for electrons in an atom or a molecule, and then the so-called Hartree-Fock- Bogoliubov model for a system of fermions interacting via the gravitational force. In a second part, we propose a new method allowing to prove the existence of the thermodynamic limit of Coulomb quantum systems. Then, we construct two Hartree-Fock-type models for infinite systems. The first is a relativistic theory deduced from Quantum Electrodynamics, allowing to describe the behavior of electrons, coupled to that of Dirac's vacuum which can become polarized. The second model describes a nonrelativistic quantum crystal in the presence of a charged defect. A new numerical method is also proposed. The last part of the thesis is devoted to spectral pollution, a phenomenon which is observed when trying to approximate eigenvalues in a gap of the essential spectrum of a self-adjoint operator, for instance for periodic Schroedinger operators or Dirac operators. (author)
Numerical Three-Dimensional Model of Airport Terminal Drainage System
Strzelecki Michał
2014-01-01
During the construction of an airport terminal it was found that as a result of the hydrostatic pressure of underground water the foundation plate of the building had dangerously shifted in the direction opposite to that of the gravitational forces. The only effective measure was to introduce a drainage system on the site. The complex geology of the area indicated that two independent drainage systems, i.e., a horizontal system in the Quaternary beds and a vertical system in the Tertiary wate...
Implementation of the Automated Numerical Model Performance Metrics System
2011-09-26
question. As of this writing, the DSRC IBM AIX machines DaVinci and Pascal, and the Cray XT Einstein all use the PBS batch queuing system for...3.3). 12 Appendix A – General Automation System This system provides general purpose tools and a general way to automatically run
Alcohol Control: Mobile Sensor System and Numerical Signal Analysis
Directory of Open Access Journals (Sweden)
Rolf SEIFERT
2016-10-01
Full Text Available An innovative mobile sensor system for alcohol control in the respiratory air is introduced. The gas sensor included in the sensor system is thermo-cyclically operated. Ethanol is the leading component in this context. However, other components occur in the breathing air which can influence the concentration determination of ethanol. Therefore, mono- ethanol samples and binary gas mixtures are measured by the sensor system and analyzed with a new calibration and evaluation procedure which is also incorporated in the system. The applications demonstrate a good substance identification capability of the sensor system and a very good concentration determination of the components.
Numerical Modelling Approaches for Sediment Transport in Sewer Systems
DEFF Research Database (Denmark)
Mark, Ole
A study of the sediment transport processes in sewers has been carried out. Based on this study a mathematical modelling system has been developed to describe the transport processes of sediments and dissolved matter in sewer systems. The modelling system consists of three sub-models which...... constitute the basic modelling system necessary to give a discription of the most dominant physical transport processes concerning particles and dissolved matter in sewer systems: A surface model. An advection-dispersion model. A sediment transport model....
A numerical study on an optimum design of a Cross-flow type Power Turbine (CPT)
International Nuclear Information System (INIS)
Ha, Jin Ho; Kim, Chul Ho
2008-01-01
A wind turbine is one of the most popular energy conversion systems to generate electricity from the natural renewable energy source and an axial-flow type wind turbine is commonly used system for the generation electricity in the wind farm nowadays. In this study, a cross-flow type turbine has been studied for the application of wind turbine for electricity generation. The target capacity of the electric power generation of the model wind turbine developing in this project is 12volts-150A/H(about 1.8Kw). The important design parameters of the model turbine impeller are the inlet and exit angle of the turbine blade, number of blade, hub/tip ratio and exit flow angle of the housing. In this study, the radial equilibrium theorem was used to decide the inlet and exit angle of the model impeller blade and CFD technique was incorporated to have performance analysis of the design model power turbine for the optimum design of the geometry of the Cross-flow Power Turbine impeller and Casing. In CFD, Navier-Stokes equation is solved with the SIMPLEC method in a general coordinates system. Realizable k-ε turbulent model with MARS scheme was used for evaluating torque of each blade in the Cross-flow Power Turbine (CPT). From the result, the designed CPT with 24 impeller blades at α=40 .deg. and β=85 .deg. of turbine blade angle was estimated to generate 1.2Nm of the indicated torque and 200watts of the indicated power. On the basis of the rules of similarity, the generating power capacity of the real size CPT that is eight times longer than the model impeller is predicted to have an 1.6kW of the output power (about 12V-130A/H or 24V-65A/H)
ADVANCED DRIVER SAFETY SUPPORT SYSTEMS FOR THE URBAN TYPE VEHICLE
Directory of Open Access Journals (Sweden)
Katarzyna JEZIERSKA-KRUPA
2015-12-01
Full Text Available Smart Power Team is currently working on the design of an urban electric vehicle designed to compete in the Shell Eco-marathon. One important aspect of this type of vehicle characteristics is it safety. The project of advanced driver assistance systems has included some proposals of such systems and the concept of their execution. The first concept, BLIS (Blind Spot Information System, is to build a system of informing a driver about vehicles appearing in the blind spot. The system constitutes a second concept, CDIS (Collision Detection and Information System, and it is designed to detect a vehicle collision and inform the team. Further systems are: DPMS (Dew Point Measurement System - a system which does not allow a situation, where the windows are fogged, OHRS (Overtaking Horn Reminder System - a system which checks overtaking and MSS (main supervision system - a supervisory system. These concepts are based on the assumption of the use of laser sensors, photoelectric, humidity and temperature, and other commercially available systems. The article presents a detailed description of driver assistance systems and virtual prototyping methodology for these systems, as well as the numerical results of the verification of one of the systems.
Directory of Open Access Journals (Sweden)
Qi Wang
2012-01-01
Full Text Available This paper deals with the oscillations of numerical solutions for the nonlinear delay differential equations in physiological control systems. The exponential θ-method is applied to p′(t=β0ωμp(t−τ/(ωμ+pμ(t−τ−γp(t and it is shown that the exponential θ-method has the same order of convergence as that of the classical θ-method. Several conditions under which the numerical solutions oscillate are derived. Moreover, it is proven that every nonoscillatory numerical solution tends to positive equilibrium of the continuous system. Finally, the main results are illustrated with numerical examples.
Alcohol control: Mobile sensor system and numerical signal analysis
Seifert, Rolf; Keller, Hubert B.; Conrad, Thorsten; Peter, Jens
2016-01-01
An innovative mobile sensor system for alcohol control in the respiratory air is introduced. The gas sensor included in the sensor system is thermo-cyclically operated. Ethanol is the leading component in this context. However, other components occur in the breathing air which can influence the concentration determination of ethanol. Therefore, mono- ethanol samples and binary gas mixtures are measured by the sensor system and analyzed with a new calibration and evaluation procedure which is ...
El Mouhayar, Rabih; Jurdak, Murad
2016-01-01
This paper explored variation of student numerical and figural reasoning approaches across different pattern generalization types and across grade level. An instrument was designed for this purpose. The instrument was given to a sample of 1232 students from grades 4 to 11 from five schools in Lebanon. Analysis of data showed that the numerical…
Sadighi, M.; Pärnänen, T.; Alderliesten, R.C.; Sayeaftabi, M.; Benedictus, R.
2012-01-01
The impact response of fiber metal laminates (FMLs), has been investigated with experiments and numerical simulations, which is reported in this article. Low-velocity impacts were carried out to study the effects of metal type and thickness within FMLs. Glare5-3/2 laminates with two aluminum layer
Numerical approach to solar ejector-compression refrigeration system
Directory of Open Access Journals (Sweden)
Zheng Hui-Fan
2016-01-01
Full Text Available A model was established for solar ejector-compression refrigeration system. The influence of generator temperature, middle-temperature, and evaporator temperature on the performance of the refrigerant system was analyzed. An optimal generator temperature is found for maximal energy efficiency ratio and minimal power consumption.
Iterated Hamiltonian type systems and applications
Tiba, Dan
2018-04-01
We discuss, in arbitrary dimension, certain Hamiltonian type systems and prove existence, uniqueness and regularity properties, under the independence condition. We also investigate the critical case, define a class of generalized solutions and prove existence and basic properties. Relevant examples and counterexamples are also indicated. The applications concern representations of implicitly defined manifolds and their perturbations, motivated by differential systems involving unknown geometries.
Early-type semidetached system LY Aurigae
International Nuclear Information System (INIS)
Li, Y.F.; Leung, K.C.
1985-01-01
In an effort to resolve a controversy regarding the configuration, mass ratio, and evolutionary status of the early-type close binary system LY Aur, the six bandpass OAO 2 observations of Heap and the ground-based observations combined by Eaton were analyzed. The Wilson and Devinney approach was used. The system is found to be semidetached, with the cooler and less massive component filling its Roche lobe, while the hotter component is close to its Roche surface. The system is not an early-type zero-age contact, as was suspected earlier. 20 references
Numerical modeling of aquifer thermal energy storage system
Energy Technology Data Exchange (ETDEWEB)
Kim, Jongchan [Korea Institute of Geoscience and Mineral Resources, Geothermal Resources Department, 92 Gwahang-no, Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Kongju National University, Department of Geoenvironmental Sciences, 182 Singwan-dong, Gongju-si, Chungnam 314-701 (Korea, Republic of); Lee, Youngmin [Korea Institute of Geoscience and Mineral Resources, Geothermal Resources Department, 92 Gwahang-no, Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Yoon, Woon Sang; Jeon, Jae Soo [nexGeo Inc., 134-1 Garak 2-dong, Songpa-gu, Seoul 138-807 (Korea, Republic of); Koo, Min-Ho; Keehm, Youngseuk [Kongju National University, Department of Geoenvironmental Sciences, 182 Singwan-dong, Gongju-si, Chungnam 314-701 (Korea, Republic of)
2010-12-15
The performance of the ATES (aquifer thermal energy storage) system primarily depends on the thermal interference between warm and cold thermal energy stored in an aquifer. Additionally the thermal interference is mainly affected by the borehole distance, the hydraulic conductivity, and the pumping/injection rate. Thermo-hydraulic modeling was performed to identify the thermal interference by three parameters and to estimate the system performance change by the thermal interference. Modeling results indicate that the thermal interference grows as the borehole distance decreases, as the hydraulic conductivity increases, and as the pumping/injection rate increases. The system performance analysis indicates that if {eta} (the ratio of the length of the thermal front to the distance between two boreholes) is lower than unity, the system performance is not significantly affected, but if {eta} is equal to unity, the system performance falls up to {proportional_to}22%. Long term modeling for a factory in Anseong was conducted to test the applicability of the ATES system. When the pumping/injection rate is 100 m{sup 3}/day, system performances during the summer and winter after 3 years of operation are estimated to be {proportional_to}125 kW and {proportional_to}110 kW, respectively. Therefore, 100 m{sup 3}/day of the pumping/injection rate satisfies the energy requirements ({proportional_to}70 kW) for the factory. (author)
Numerical Solution of Magnetostatic Field of Maglev System
Directory of Open Access Journals (Sweden)
Jaroslav Sobotka
2008-01-01
Full Text Available The paper deals with the design of the levitation and guidance system of the levitation train Transrapid 08 by means of QuickField 5.0 – a 2D program formagnetic electromagnetic fields solutions.
Numerical Modeling of Disc Brake System in Frictional Contact
Directory of Open Access Journals (Sweden)
A. Belhocine
2014-03-01
Full Text Available Safety aspect in automotive engineering has been considered as a number one priority in development of new vehicle. Each single system has been studied and developed in order to meet safety requirement. Instead of having air bag, good suspension systems, good handling and safe cornering, there is one most critical system in the vehicle which is brake systems. The objective of this work is to investigate and analyse the temperature distribution of rotor disc during braking operation using ANSYS Multiphysics. The work uses the finite element analysis techniques to predict the temperature distribution on the full and ventilated brake disc and to identify the critical temperature of the rotor by holding account certain parameters such as; the material used, the geometric design of the disc and the mode of braking. The analysis also gives us, the heat flux distribution for the two discs.
Exchange bias of patterned systems: Model and numerical simulation
International Nuclear Information System (INIS)
Garcia, Griselda; Kiwi, Miguel; Mejia-Lopez, Jose; Ramirez, Ricardo
2010-01-01
The magnitude of the exchange bias field of patterned systems exhibits a notable increase in relation to the usual bilayer systems, where a continuous ferromagnetic film is deposited on an antiferromagnet insulator. Here we develop a model, and implement a Monte Carlo calculation, to interpret the experimental observations which is consistent with experimental results, on the basis of assuming a small fraction of spins pinned ferromagnetically in the antiferromagnetic interface layer.
Numerical investigation on asymmetric bilayer system at integer filling factor
Czech Academy of Sciences Publication Activity Database
Nomura, K.; Yoshioka, D.; Jungwirth, Tomáš; MacDonald, A. H.
2004-01-01
Roč. 22, - (2004), s. 60-63 ISSN 1386-9477. [International Conference on Electronic Properties of Two-Dimensional Systems /15./. Nara, 14.07.2003-18.07.2003] Institutional research plan: CEZ:AV0Z1010914 Keywords : quantum Hall ferromagnet * asymmetric bilayer systems * anisotropy * stripe states Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.898, year: 2004
Numerical study of PV/T-SAHP system
Institute of Scientific and Technical Information of China (English)
Gang PEI; Jie JI; Ke-liang LIU; Han-feng HE; Ai-guo JIANG
2008-01-01
In order to utilize solar energy effectively and to achieve a higher electrical efficiency by limiting the operating temperature of the photovoltaic (PV) panel, a novel photovoltaic/thermal solar-assisted heat pump (PV/T-SAHP) system was proposed and constructed. The hybrid solar system generates electricity and thermal energy simultaneously. A distributed parameters model of the PV/T-SAHP system was developed and applied to analyze the system dynamic performance in terms of PV action, photothermal action and Rankine cycle processes. The simulation results indicated that the coefficient of performance (COP) of the proposed PV/T-SAHP can be much better than that of the conventional heat pump. Both PV-efficiency and photothermic efficiency have been improved considerably. The results also showed that the performance of this PV/T-SAHP system was strongly influenced by the evaporator area, tube pitch and tilt angle of the PV/T evaporator, which are the key factors in PV/T-SAHP system optimization and PV/T evaporator design.
Adaptive polymeric system for Hebbian type learning
2011-01-01
Abstract We present the experimental realization of an adaptive polymeric system displaying a ?learning behaviour?. The system consists on a statistically organized networks of memristive elements (memory-resitors) based on polyaniline. In a such network the path followed by the current increments its conductivity, a property which makes the system able to mimic Hebbian type learning and have application in hardware neural networks. After discussing the working principle of ...
International Nuclear Information System (INIS)
Xiao Gang; Li Zhizhong
2004-01-01
Based on integral equaiton describing the life-history of Markov system, six types of estimators of the current unavailability of Markov system with dependent repair are propounded. Combining with the biased sampling of state transition time of system, six types of Monte Carlo for estimating the current unavailability are given. Two numerical examples are given to deal with the variances and efficiencies of the six types of Monte Carlo methods. (authors)
Relaxation in control systems of subdifferential type
Tolstonogov, A. A.
2006-02-01
In a separable Hilbert space we consider a control system with evolution operators that are subdifferentials of a proper convex lower semicontinuous function depending on time. The constraint on the control is given by a multivalued function with non-convex values that is lower semicontinuous with respect to the variable states. Along with the original system we consider the system in which the constraint on the control is the upper semicontinuous convex-valued regularization of the original constraint. We study relations between the solution sets of these systems. As an application we consider a control variational inequality. We give an example of a control system of parabolic type with an obstacle.
Relaxation in control systems of subdifferential type
International Nuclear Information System (INIS)
Tolstonogov, A A
2006-01-01
In a separable Hilbert space we consider a control system with evolution operators that are subdifferentials of a proper convex lower semicontinuous function depending on time. The constraint on the control is given by a multivalued function with non-convex values that is lower semicontinuous with respect to the variable states. Along with the original system we consider the system in which the constraint on the control is the upper semicontinuous convex-valued regularization of the original constraint. We study relations between the solution sets of these systems. As an application we consider a control variational inequality. We give an example of a control system of parabolic type with an obstacle
Various types of numerical schema for the one-dimensional spherical geometry transport equation
International Nuclear Information System (INIS)
Jaber, Abdelouhab.
1981-07-01
Mathematical and numerical studies of new schemas possessing high accuracy spatial variable properties are described and the corresponding studies presented. In order to do this, the [0,R] x [-1,+1] rectangle is decomposad into Ksub(ij) = [rsub(i),rsub(i+1)] x [μsub(j),μsub(j+1) ] rectangles. Continuous finite element methods employing polynominals of degree 1 in μ and degree 2 in r are defined for each elements. In chapter I, different ways of rendering the particular equation (for μ = -1) discrete are studied. In chapter II, numerical schemas are described and their stability investigated. In chapter III, error estimation theories are exposed and numerical results for different second members, S, given [fr
Directory of Open Access Journals (Sweden)
Wójcik Damian K.
2017-01-01
Full Text Available Meteorological data concerning the severe convective system from the 21 August 2007 are analyzed in this study. Compiled information allows to understand the reason for the storm development and to identify its fundamental convective mode. Next, the EULAG model is utilized to perform an idealized test that shows a downwind–developing storm growth in an environment comparable to the one that was observed on the 21 August 2007 in the Masurian Lake District. Finally, the COSMO numerical weather prediction model is applied to reconstruct the storm development. The experiment is carried out for various computational grids having the horizontal grid length between 7.0 and 0.55 km. It turns out that the COSMO model is capable in simulating storms of that type. Since the model is used for operational weather forecasting in Poland the evaluation of this skill contributes to the increase of public safety.
Modeling multibody systems with uncertainties. Part II: Numerical applications
International Nuclear Information System (INIS)
Sandu, Corina; Sandu, Adrian; Ahmadian, Mehdi
2006-01-01
This study applies generalized polynomial chaos theory to model complex nonlinear multibody dynamic systems operating in the presence of parametric and external uncertainty. Theoretical and computational aspects of this methodology are discussed in the companion paper 'Modeling Multibody Dynamic Systems With Uncertainties. Part I: Theoretical and Computational Aspects .In this paper we illustrate the methodology on selected test cases. The combined effects of parametric and forcing uncertainties are studied for a quarter car model. The uncertainty distributions in the system response in both time and frequency domains are validated against Monte-Carlo simulations. Results indicate that polynomial chaos is more efficient than Monte Carlo and more accurate than statistical linearization. The results of the direct collocation approach are similar to the ones obtained with the Galerkin approach. A stochastic terrain model is constructed using a truncated Karhunen-Loeve expansion. The application of polynomial chaos to differential-algebraic systems is illustrated using the constrained pendulum problem. Limitations of the polynomial chaos approach are studied on two different test problems, one with multiple attractor points, and the second with a chaotic evolution and a nonlinear attractor set. The overall conclusion is that, despite its limitations, generalized polynomial chaos is a powerful approach for the simulation of multibody dynamic systems with uncertainties
Modeling multibody systems with uncertainties. Part II: Numerical applications
Energy Technology Data Exchange (ETDEWEB)
Sandu, Corina, E-mail: csandu@vt.edu; Sandu, Adrian; Ahmadian, Mehdi [Virginia Polytechnic Institute and State University, Mechanical Engineering Department (United States)
2006-04-15
This study applies generalized polynomial chaos theory to model complex nonlinear multibody dynamic systems operating in the presence of parametric and external uncertainty. Theoretical and computational aspects of this methodology are discussed in the companion paper 'Modeling Multibody Dynamic Systems With Uncertainties. Part I: Theoretical and Computational Aspects .In this paper we illustrate the methodology on selected test cases. The combined effects of parametric and forcing uncertainties are studied for a quarter car model. The uncertainty distributions in the system response in both time and frequency domains are validated against Monte-Carlo simulations. Results indicate that polynomial chaos is more efficient than Monte Carlo and more accurate than statistical linearization. The results of the direct collocation approach are similar to the ones obtained with the Galerkin approach. A stochastic terrain model is constructed using a truncated Karhunen-Loeve expansion. The application of polynomial chaos to differential-algebraic systems is illustrated using the constrained pendulum problem. Limitations of the polynomial chaos approach are studied on two different test problems, one with multiple attractor points, and the second with a chaotic evolution and a nonlinear attractor set. The overall conclusion is that, despite its limitations, generalized polynomial chaos is a powerful approach for the simulation of multibody dynamic systems with uncertainties.
Scientific applications and numerical algorithms on the midas multiprocessor system
International Nuclear Information System (INIS)
Logan, D.; Maples, C.
1986-01-01
The MIDAS multiprocessor system is a multi-level, hierarchial structure designed at the Advanced Computer Architecture Laboratory of the University of California's Lawrence Berkeley Laboratory. A two-stage, 11-processor system has been operational for over a year and is currently undergoing expansion. It has been employed to investigate the performance of different methods of decomposing various problems and algorithms into a multiprocessor environment. The results of such tests on a variety of applications such as scientific data analysis, Monte Carlo calculations, and image processing, are discussed. Often such decompositions involve investigating the parallel structure of fundamental algorithms. Several basic algorithms dealing with random number generation, matrix diagonalization, fast Fourier transforms, and finite element methods in solving partial differential equations are also discussed. The performance and projected extensibilities of these decompositions on the MIDAS system are reported
Numerical Modeling of a Shallow Borehole Thermal Energy Storage System
Catolico, N.; Ge, S.; Lu, N.; McCartney, J. S.
2014-12-01
Borehole thermal energy storage (BTES) combined with solar thermal energy harvesting is an economic technological system to garner and store energy as well as an environmentally-sustainable alternative for the heating of buildings. The first community-scale BTES system in North America was installed in 2007 in the Drake Landing Solar Community (DLSC), about 35 miles south of Calgary, Canada. The BTES system involves direct circulation of water heated from solar thermal panels in the summer into a storage tank, after which it is circulate within an array of 144 closed-loop geothermal heat exchangers having a depth of 35 m and a spacing of 2.5 m. In the winter the circulation direction is reversed to supply heat to houses. Data collection over a six year period indicates that this system can supply more than 90% of the winter heating energy needs for 52 houses in the community. One major challenge facing the BTES system technology is the relatively low annual efficiency, i.e., the ratio of energy input and output is in the range of 15% to 40% for the system in Drake Landing. To better understand the working principles of BTES and to improve BTES performance for future applications at larger scales, a three-dimensional transient coupled fluid and heat transfer model is established using TOUGH2. The time-dependent injection temperatures and circulation rate measured over the six years of monitoring are used as model input. The simulations are calibrated using soil temperature data measured at different locations over time. The time-dependent temperature distributions within the borehole region agree well with the measured temperatures for soil with an intrinsic permeability of 10e-19 m2, an apparent thermal conductivity of 2.03 W/m°C, and a volumetric heat capacity of 2.31 MJ/m-3°C. The calibrated model serves as the basis for a sensitivity analysis of soil and operational parameters on BTES system efficiency preformed with TOUGH2. Preliminary results suggest 1) BTES
Directory of Open Access Journals (Sweden)
Y. Saiki
2007-09-01
Full Text Available An infinite number of unstable periodic orbits (UPOs are embedded in a chaotic system which models some complex phenomenon. Several algorithms which extract UPOs numerically from continuous-time chaotic systems have been proposed. In this article the damped Newton-Raphson-Mees algorithm is reviewed, and some important techniques and remarks concerning the practical numerical computations are exemplified by employing the Lorenz system.
Explicit appropriate basis function method for numerical solution of stiff systems
International Nuclear Information System (INIS)
Chen, Wenzhen; Xiao, Hongguang; Li, Haofeng; Chen, Ling
2015-01-01
Highlights: • An explicit numerical method called the appropriate basis function method is presented. • The method differs from the power series method for obtaining approximate numerical solutions. • Two cases show the method is fit for linear and nonlinear stiff systems. • The method is very simple and effective for most of differential equation systems. - Abstract: In this paper, an explicit numerical method, called the appropriate basis function method, is presented. The explicit appropriate basis function method differs from the power series method because it employs an appropriate basis function such as the exponential function, or periodic function, other than a polynomial, to obtain approximate numerical solutions. The method is successful and effective for the numerical solution of the first order ordinary differential equations. Two examples are presented to show the ability of the method for dealing with linear and nonlinear systems of differential equations
Numerical analysis of power system transients and dynamics
Ametani, Akihiro
2015-01-01
This book describes the three major power system transient and dynamics simulation tools based on a circuit-theory based approach which are most widely used all over the world (EMTP-ATP, EMTP-RV and EMTDC/PSCAD), together with other powerful simulation tools such as XTAP.
Numerical Integration of Stiff System of Ordinary Differential ...
African Journals Online (AJOL)
The goal of this work is to develop, analyse and implement a K-step Implicit Rational Runge-Kutta schemes for Integration of Stiff system of Ordinary differential Equations. Its development adopted Taylor and Binomial series expansion Techniques to generate its parameters. The analysis of its basic properties adopted ...
A Linguistic Image of Nature: The Burmese Numerative Classifier System
Becker, Alton L.
1975-01-01
The Burmese classifier system is coherent because it is based upon a single elementary semantic dimension: deixis. On that dimension, four distances are distinguished, distances which metaphorically substitute for other conceptual relations between people and other living beings, people and things, and people and concepts. (Author/RM)
Using session types as an effect system
Directory of Open Access Journals (Sweden)
Dominic Orchard
2016-02-01
Full Text Available Side effects are a core part of practical programming. However, they are often hard to reason about, particularly in a concurrent setting. We propose a foundation for reasoning about concurrent side effects using sessions. Primarily, we show that session types are expressive enough to encode an effect system for stateful processes. This is formalised via an effect-preserving encoding of a simple imperative language with an effect system into the pi-calculus with session primitives and session types (into which we encode effect specifications. This result goes towards showing a connection between the expressivity of session types and effect systems. We briefly discuss how the encoding could be extended and applied to reason about and control concurrent side effects.
Numerical study of a water distillation system using solar energy
International Nuclear Information System (INIS)
Zarzoum, K.; Zhani, K.; Bacha, H. Ben
2016-01-01
This paper tackles an optimization approach in order to boost the fresh water production of a new design of a solar still which is located at Sfax engineering national school in Tunisia. This optimization approach is based upon the above mentioned design's improvement by coupling the conventional solar still into at a condenser, solar air and water collector and humidifier. This new concept of a distiller solar still using humidification- dehumidification processes (HD) is exploited for the desalination purpose. As a result of this work, the humidification- dehumidification processes have an essential effect in improving the solar still performance. Performance has been predicted theoretically in terms of water and inner glass cover temperatures, the inlet temperature of air and water of the new concept of distiller on water condensation rate and fresh water production. A general model based on heat and mass transfers in each component of the unit has been developed in steady dynamic regime. The developed model is used, simulating the HD system, to investigate the influence of the meteorological and operating parameters on the system productivity. The obtained set of ordinary differential equations has been converted to a set of algebraic system of equations by the functional approximation method of orthogonal collocation. The developed model is used to simulate the HD system in order to investigate the steady state behavior of each component of the unit and the entire system exposed to a variation of the entrance parameters and meteorological conditions. The obtained results were compared with those of other studies and the comparison gives a good validity of the present results
Numerical study of a water distillation system using solar energy
Energy Technology Data Exchange (ETDEWEB)
Zarzoum, K.; Zhani, K. [Sfax University, (Turkey); Bacha, H. Ben [Prince Sattam Bin Abdulaziz University, Alkharj (Saudi Arabia)
2016-02-15
This paper tackles an optimization approach in order to boost the fresh water production of a new design of a solar still which is located at Sfax engineering national school in Tunisia. This optimization approach is based upon the above mentioned design's improvement by coupling the conventional solar still into at a condenser, solar air and water collector and humidifier. This new concept of a distiller solar still using humidification- dehumidification processes (HD) is exploited for the desalination purpose. As a result of this work, the humidification- dehumidification processes have an essential effect in improving the solar still performance. Performance has been predicted theoretically in terms of water and inner glass cover temperatures, the inlet temperature of air and water of the new concept of distiller on water condensation rate and fresh water production. A general model based on heat and mass transfers in each component of the unit has been developed in steady dynamic regime. The developed model is used, simulating the HD system, to investigate the influence of the meteorological and operating parameters on the system productivity. The obtained set of ordinary differential equations has been converted to a set of algebraic system of equations by the functional approximation method of orthogonal collocation. The developed model is used to simulate the HD system in order to investigate the steady state behavior of each component of the unit and the entire system exposed to a variation of the entrance parameters and meteorological conditions. The obtained results were compared with those of other studies and the comparison gives a good validity of the present results.
STUDY AND NUMERICAL SIMULATION OF SOLAR SYSTEM FOR AIR HEATING
Directory of Open Access Journals (Sweden)
M. Ghodbane
2016-01-01
Full Text Available The use of solar energy in sunny countries, is an effective outil for compensate the lack in the energy, their benefits are not related only to its economic benefits but especially for the environmental protection, so we must find solutions to the problems of pollution. This work is a theoretical study of a solar flat plate collector ; air is used as the heat transfer fluid. In this study, we established in first step the calculation of solar radiation in various sites in Algeria (Adrar, El Oued, Bechar, Biskra and Tamanrasset. The second step is the parameters influence study of the sites and climate on the performance of our collector. The results obtained are encouraging for the use of this type in the heating in the winter, also it can be used in different kinds of drying.
Research status and some results of numerical system to study regional environment: SPEEDI-MP
International Nuclear Information System (INIS)
Chino, Masamichi
2004-01-01
Research status and some results of 'Numerical system to study regional environment: SPEEDI-MP', which reproduces circulations of materials in the atmospheric, oceanic and terrestrial environments, are introduced. The purpose of this system are the development of various environmental models, the connection of atmospheric, oceanic and terrestrial models and the construction of research bases for numerical environmental studies. In addition to the accurate prediction of environmental behavior of radionuclides, the system has been applied to the non-nuclear fields, e.g., numerical analysis of environmental effects to volcanic gases from Miyake Jima, real-time prediction of the migration of rice planthoppers from Eastern Asia. (author)
Numerical simulations of thermal conductivity in dissipative two-dimensional Yukawa systems.
Khrustalyov, Yu V; Vaulina, O S
2012-04-01
Numerical data on the heat transfer constants in two-dimensional Yukawa systems were obtained. Numerical study of the thermal conductivity and diffusivity was carried out for the equilibrium systems with parameters close to conditions of laboratory experiments with dusty plasma. For calculations of heat transfer constants the Green-Kubo formulas were used. The influence of dissipation (friction) on the heat transfer processes in nonideal systems was investigated. The approximation of the coefficient of thermal conductivity is proposed. Comparison of the obtained results to the existing experimental and numerical data is discussed.
Delay systems from theory to numerics and applications
Lafay, Jean-François; Sipahi, Rifat
2014-01-01
This volume is the first of the new series Advances in Dynamics and Delays. It offers the latest advances in the research of analyzing and controlling dynamical systems with delays, which arise in many real-world problems. The contributions in this series are a collection across various disciplines, encompassing engineering, physics, biology, and economics, and some are extensions of those presented at the IFAC (International Federation of Automatic Control) conferences since 2011. The series is categorized in five parts covering the main themes of the contributions: · Stability Analysis and Control Design · Networks and Graphs · Time Delay and Sampled-Data Systems · Computational and Software Tools · Applications This volume will become a good reference point for researchers and PhD students in the field of delay systems, and for those willing to learn more about the field, and it will also be a resource for control engine...
Numerical simulation of nuclear power plants on multiprocessor systems
International Nuclear Information System (INIS)
Boeer, R.; Finnemann, H.; Mueller, R.; Krapf, J.
1990-04-01
The present final report gives an account of work performed and results obtained at Siemens/KWU within the frame of SUPRENUM project. The coupled neutron kinetics - thermal hydraulics program system 3D-SIM for the calculation of steady-state and transient conditions in the core and in the coolant loops of light water reactors has been developed. Making efficient use of the parallel computing architecture required the implementation of novel, purpose-built software concepts which can be characterized by multigrid algorithms and parallelization by domain decomposition. The modules treating the reactor core are 3D-NEUT for neutron kinetics and 3D-THERM for thermal hydraulics, the remaining system and control components being represented by the module NLOOP. This modular structure is a main feature of 3D-SIM which allows a flexible choice of applications, employing modules individually or in combinations to fulfil a specific calculation task. In particular, 3D-SIM reactor core representation is fully 3-dimensional for both neutron diffusion and thermal-hydraulic equations, allowing coupled calculations and evaluation of crossflow between fuel elements or subchannels. Including also the loops and plant models, 3D-SIM is a powerful analytical tool for simulating pressurized plant response to a wide spectrum of events. (orig.) With 25 refs., 11 figs [de
Information system conflicts: causes and types
Boonstra, Albert; de Vries, Jan
2015-01-01
Conflicts are an inherent part of organizational life and managers deal with confrontations and conflicts on an almost daily basis. Information Systems (IS) implementations are a type of change that often leads to open or hidden conflicts. Managers and others involved can only deal with such conflicts effectively if they understand the nature and causes of information system conflicts (IS conflicts). To contribute to such an understanding, this study focuses on the analysis of IS conflicts. I...
Hanger-type laundry monitor system
International Nuclear Information System (INIS)
Aoyama, Kei; Kouno, Yoshio; Yanagishima, Ryouhei; Ikeda, Yasuyuki; Nakatani, Masahiro
1987-01-01
Laundry monitor is installed in nuclear power plants or other nuclear facilities in order to efficiently detect radioactive contamination remains on the surfaces of the working clothes which were used in the controlled area and washed afterward. The number of the working clothes which must be measured has been increasing in accordance with the increase of the nuclear facilities. This fact and recent intensified radiation control require automatic, high-speed and high sensitive measurement. Conveyer-type laundry monitor in which the working clothes are inserted by the metal net conveyer has been generally used, and recently new system with an automatic folder has become more popular. But, this type of system has not so big capacity because the clothes are conveyed longitudinally and also requires considerable wide space when installed. Fuji electric Co., Ltd. has been engaging in research and development for an optimum laundry monitor system used in nuclear facilities since the joint investigation with ten electric power companies in Japan in 1982. Consequently hanger-type laundry monitor system using automatic hanger conveyer was developed and 2 systems were delivered to Chubu Electric Power Co., Ltd. in 1986. This system permits to detect radioactive contamination on the working clothes, pick the contaminated clothes out and fold the uncontaminated clothes fully automatically and continuously. Moreover it allows to shorten the measurement time because the clothes are conveyed transversely and save the installation space, so that this will be regarded as considerably complete system in the world. This report describes the outline of the hanger-type laundry monitor system. (author)
Conceptual and numerical modeling approach of the Guarani Aquifer System
Directory of Open Access Journals (Sweden)
L. Rodríguez
2013-01-01
Full Text Available In large aquifers, relevant for their considerable size, regional groundwater modeling remains challenging given geologic complexity and data scarcity in space and time. Yet, it may be conjectured that regional scale groundwater flow models can help in understanding the flow system functioning and the relative magnitude of water budget components, which are important for aquifer management. The Guaraní Aquifer System is the largest transboundary aquifer in South America. It contains an enormous volume of water; however, it is not well known, being difficult to assess the impact of exploitation currently used to supply over 25 million inhabitants. This is a sensitive issue because the aquifer is shared by four countries. Moreover, an integrated groundwater model, and therefore a global water balance, were not available. In this work, a transient regional scale model for the entire aquifer based upon five simplified, equally plausible conceptual models represented by different hydraulic conductivity parametrizations is used to analyze the flow system and water balance components. Combining an increasing number of hydraulic conductivity zones and an appropriate set of boundary conditions, the hypothesis of a continuous sedimentary unit yielded errors within the calibration target in a regional sense. The magnitude of the water budget terms resulted very similar for all parametrizations. Recharge and stream/aquifer fluxes were the dominant components representing, on average, 84.2% of total inflows and 61.4% of total outflows, respectively. However, leakage was small compared to stream discharges of main rivers. For instance, the simulated average leakage for the Uruguay River was 8 m^{3} s^{−1} while the observed absolute minimum discharge was 382 m^{3} s^{−1}. Streams located in heavily pumped regions switched from a gaining condition in early years to a losing condition over time. Water is discharged through
Conceptual and numerical modeling approach of the Guarani Aquifer System
Rodríguez, L.; Vives, L.; Gomez, A.
2013-01-01
In large aquifers, relevant for their considerable size, regional groundwater modeling remains challenging given geologic complexity and data scarcity in space and time. Yet, it may be conjectured that regional scale groundwater flow models can help in understanding the flow system functioning and the relative magnitude of water budget components, which are important for aquifer management. The Guaraní Aquifer System is the largest transboundary aquifer in South America. It contains an enormous volume of water; however, it is not well known, being difficult to assess the impact of exploitation currently used to supply over 25 million inhabitants. This is a sensitive issue because the aquifer is shared by four countries. Moreover, an integrated groundwater model, and therefore a global water balance, were not available. In this work, a transient regional scale model for the entire aquifer based upon five simplified, equally plausible conceptual models represented by different hydraulic conductivity parametrizations is used to analyze the flow system and water balance components. Combining an increasing number of hydraulic conductivity zones and an appropriate set of boundary conditions, the hypothesis of a continuous sedimentary unit yielded errors within the calibration target in a regional sense. The magnitude of the water budget terms resulted very similar for all parametrizations. Recharge and stream/aquifer fluxes were the dominant components representing, on average, 84.2% of total inflows and 61.4% of total outflows, respectively. However, leakage was small compared to stream discharges of main rivers. For instance, the simulated average leakage for the Uruguay River was 8 m3 s-1 while the observed absolute minimum discharge was 382 m3 s-1. Streams located in heavily pumped regions switched from a gaining condition in early years to a losing condition over time. Water is discharged through the aquifer boundaries, except at the eastern boundary. On average
Efficient numerical methods for fluid- and electrodynamics on massively parallel systems
Energy Technology Data Exchange (ETDEWEB)
Zudrop, Jens
2016-07-01
In the last decade, computer technology has evolved rapidly. Modern high performance computing systems offer a tremendous amount of computing power in the range of a few peta floating point operations per second. In contrast, numerical software development is much slower and most existing simulation codes cannot exploit the full computing power of these systems. Partially, this is due to the numerical methods themselves and partially it is related to bottlenecks within the parallelization concept and its data structures. The goal of the thesis is the development of numerical algorithms and corresponding data structures to remedy both kinds of parallelization bottlenecks. The approach is based on a co-design of the numerical schemes (including numerical analysis) and their realizations in algorithms and software. Various kinds of applications, from multicomponent flows (Lattice Boltzmann Method) to electrodynamics (Discontinuous Galerkin Method) to embedded geometries (Octree), are considered and efficiency of the developed approaches is demonstrated for large scale simulations.
SELECT NUMERICAL METHODS FOR MODELING THE DYNAMICS SYSTEMS
Directory of Open Access Journals (Sweden)
Tetiana D. Panchenko
2016-07-01
Full Text Available The article deals with the creation of methodical support for mathematical modeling of dynamic processes in elements of the systems and complexes. As mathematical models ordinary differential equations have been used. The coefficients of the equations of the models can be nonlinear functions of the process. The projection-grid method is used as the main tool. It has been described iterative method algorithms taking into account the approximate solution prior to the first iteration and proposed adaptive control computing process. The original method of estimation error in the calculation solutions as well as for a given level of error of the technique solutions purpose adaptive method for solving configuration parameters is offered. A method for setting an adaptive method for solving the settings for a given level of error is given. The proposed method can be used for distributed computing.
Numerical results on noise-induced dynamics in the subthreshold regime for thermoacoustic systems
Gupta, Vikrant; Saurabh, Aditya; Paschereit, Christian Oliver; Kabiraj, Lipika
2017-03-01
Thermoacoustic instability is a serious issue in practical combustion systems. Such systems are inherently noisy, and hence the influence of noise on the dynamics of thermoacoustic instability is an aspect of practical importance. The present work is motivated by a recent report on the experimental observation of coherence resonance, or noise-induced coherence with a resonance-like dependence on the noise intensity as the system approaches the stability margin, for a prototypical premixed laminar flame combustor (Kabiraj et al., Phys. Rev. E, 4 (2015)). We numerically investigate representative thermoacoustic models for such noise-induced dynamics. Similar to the experiments, we study variation in system dynamics in response to variations in the noise intensity and in a critical control parameter as the systems approach their stability margins. The qualitative match identified between experimental results and observations in the representative models investigated here confirms that coherence resonance is a feature of thermoacoustic systems. We also extend the experimental results, which were limited to the case of subcritical Hopf bifurcation, to the case of supercritical Hopf bifurcation. We identify that the phenomenon has qualitative differences for the systems undergoing transition via subcritical and supercritical Hopf bifurcations. Two important practical implications are associated with the findings. Firstly, the increase in noise-induced coherence as the system approaches the onset of thermoacoustic instability can be considered as a precursor to the instability. Secondly, the dependence of noise-induced dynamics on the bifurcation type can be utilised to distinguish between subcritical and supercritical bifurcation prior to the onset of the instability.
A Type System for Dynamic Web Documents
DEFF Research Database (Denmark)
Schwartzbach, Michael Ignatieff; Sandholm, Anders
2000-01-01
Many interactive Web services use the CGI interface for communication with clients. They will dynamically create HTML documents that are presented to the client who then resumes the interaction by submitting data through incorporated form fields. This protocol is difficult to statically type-chec...... system is based on a flow analysis of which we prove soundness. We present an efficient runtime implementation that respects the semantics of only well-typed programs. This work is fully implemented as part of the system for defining interactive Web services.......Many interactive Web services use the CGI interface for communication with clients. They will dynamically create HTML documents that are presented to the client who then resumes the interaction by submitting data through incorporated form fields. This protocol is difficult to statically type...
National Oceanic and Atmospheric Administration, Department of Commerce — The Navy Operational Global Atmospheric Prediction System (NOGAPS) provides numerical guidance and products in support of a wide range of Navy oceanographic and...
An efficient numerical approach to electrostatic microelectromechanical system simulation
International Nuclear Information System (INIS)
Pu, Li
2009-01-01
Computational analysis of electrostatic microelectromechanical systems (MEMS) requires an electrostatic analysis to compute the electrostatic forces acting on micromechanical structures and a mechanical analysis to compute the deformation of micromechanical structures. Typically, the mechanical analysis is performed on an undeformed geometry. However, the electrostatic analysis is performed on the deformed position of microstructures. In this paper, a new efficient approach to self-consistent analysis of electrostatic MEMS in the small deformation case is presented. In this approach, when the microstructures undergo small deformations, the surface charge densities on the deformed geometry can be computed without updating the geometry of the microstructures. This algorithm is based on the linear mode shapes of a microstructure as basis functions. A boundary integral equation for the electrostatic problem is expanded into a Taylor series around the undeformed configuration, and a new coupled-field equation is presented. This approach is validated by comparing its results with the results available in the literature and ANSYS solutions, and shows attractive features comparable to ANSYS. (general)
International Nuclear Information System (INIS)
Roa, A M; Aumelas, V; MaItre, T; Pellone, C
2010-01-01
The aim of this paper is to present the results of the analysis of a Darrieus-type cross flow water turbine in bare and shrouded configurations. Numerical results are compared to experimental data and differences found in values are also highlighted. The benefit of the introduction of a channelling device, which generates an efficiency increment factor varying from 2 to 5, depending on the configuration, is discussed.
International Nuclear Information System (INIS)
Chen, Wen-Lih; Wong, King-Leung; Po, Li-Wen
2012-01-01
Highlights: ► A numerical model has been applied to study the performance of a gamma-type Stirling engine. ► A prototype engine has been built to correct the values of some factors in the model. ► The regeneration effectiveness is most prominent on efficiency. ► Engine speed is most effective on the engine power. ► The rotation arm and initial gas pressure are also influential factors on engine power. - Abstract: In this study, a prototype helium-changed twin-power-piston γ-type Stirling engine has been built, and some of its geometrical and operational parameters have been investigated by a numerical model. Data taken from the prototype engine have been used to correct the values of some factors in the numerical model. The results include volume and temperature variations in the expansion and compression chambers, p–v diagrams, and the effects of regeneration effectiveness, the crank radius of the power piston, the initial pressure of working gas, and the rotation speed on engine’s power and efficiency. It has been found that regeneration effectiveness poses the most prominent effect on efficiency, while engine speed is most effective on the engine power within the range of engine speed investigated in this study. This study offers invaluable guides for the design and optimization of γ-type Stirling engines with similar construction.
Numerical investigation on thermal and fluid dynamic behaviors of solar chimney building systems
International Nuclear Information System (INIS)
Manca, O.; Nardini, S.; Romano, P.; Mihailov, E.
2013-01-01
Full text: Buildings as big energy-consuming systems require large amount of energy to operate. Globally, buildings are responsible for approximately 40% of total world annual energy consumption. Sustainable buildings with renewable energy systems are trying to operate independently without consumption of conventional resources. Renewable energy is a significant approach to reduce resource consumption in sustainable building. A solar chimney is essentially divided into two parts, one - the solar air heater (collector) and second - the chimney. Two configurations of solar chimney are usually used: vertical solar chimney with vertical absorber geometry, and roof solar chimney. For vertical solar chimney, vertical glass is used to gain solar heat. Designing a solar chimney includes height, width and depth of cavity, type of glazing, type of absorber, and inclusion of insulation or thermal mass. Besides these system parameters, other factors such as the location, climate, and orientation can also affect its performance. In this paper a numerical investigation on a prototypal solar chimney system integrated in a south facade of a building is presented. The analysis is carried out on a three-dimensional model in air flow and the governing equations are given in terms of k-s turbulence model. Two geometrical configurations are investigated: 1) a channel with vertical parallel walls and 2) a channel with principal walls one vertical and the other inclined. The problem is solved by means of the commercial code Ansys-Fluent and the results are performed for a uniform wall heat flux on the vertical wall is equal to 300 and 600 W/m2. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles in order to evaluate the differences between the two base configurations and thermal and fluid dynamic behaviors. Further, the ground effect on thermal performances is examined. key words: mathematical modeling, solar chimney
Numerical Modeling of Limiting Oxygen Index Apparatus for Film Type Fuels
Directory of Open Access Journals (Sweden)
Amit Kumar
2012-12-01
Full Text Available A detailed three-dimensional numerical model is used to compute the flow pattern and the flame behavior of thin solid fuels in a rectangular column that resembles a standard Limiting Oxygen Index (LOI device. The model includes full Navier-Stokes equations for mixed buoyant-forced flow and finite rate combustion and pyrolysis reactions so that the sample LOI can be computed to study the effect of feeding flow rate, sample width and gravity levels. In addition to the above parameters, the sample location in the column and the column cross-sectional area are also investigated on their effect on the ambient air entrainment from the top.
One Language, Two Number-Word Systems and Many Problems: Numerical Cognition in the Czech Language
Pixner, S.; Zuber, J.; Hermanova, V.; Kaufmann, L.; Nuerk, H.-C.; Moeller, K.
2011-01-01
Comparing numerical performance between different languages does not only mean comparing different number-word systems, but also implies a comparison of differences regarding culture or educational systems. The Czech language provides the remarkable opportunity to disentangle this confound as there exist two different number-word systems within…
Numerical solution of ordinary differential equations. For classical, relativistic and nano systems
International Nuclear Information System (INIS)
Greenspan, D.
2006-01-01
An up-to-date survey on numerical solutions with theory, intuition and applications. Ordinary differential equations (ODE) play a significant role in mathematics, physics and engineering sciences, and thus are part of relevant college and university courses. Many problems, however, both traditional and modern, do not possess exact solutions, and must be treated numerically. Usually this is done with software packages, but for this to be efficient requires a sound understanding of the mathematics involved. This work meets the need for an affordable textbook that helps in understanding numerical solutions of ODE. Carefully structured by an experienced textbook author, it provides a survey of ODE for various applications, both classical and modern, including such special applications as relativistic and nano systems. The examples are carefully explained and compiled into an algorithm, each of which is presented generically, independent of a specific programming language, while each chapter is rounded off with exercises. The text meets the demands of MA200 courses and of the newly created Numerical Solution of Differential Equations courses, making it ideal for both students and lecturers in physics, mathematics, mechanical engineering, electrical engineering, as well as for physicists, mathematicians, engineers, and electrical engineers. From the Contents - Euler's Method - Runge-Kutta Methods - The Method of Taylor Expansions - Large Second Order Systems with Application to Nano Systems - Completely Conservative, Covariant Numerical Methodology - Instability - Numerical Solution of Tridiagonal Linear Algebraic Systems and Related Nonlinear Systems - Approximate Solution of Boundary Value Problems - Special Relativistic Motion - Special Topics - Appendix: Basic Matrix Operations - Bibliography. (orig.) (orig.)
Information system conflicts: causes and types
Directory of Open Access Journals (Sweden)
Albert Boonstra
2015-01-01
Full Text Available Conflicts are an inherent part of organizational life and managers deal with confrontations and conflicts on an almost daily basis. Information Systems (IS implementations are a type of change that often leads to open or hidden conflicts. Managers and others involved can only deal with such conflicts effectively if they understand the nature and causes of information system conflicts (IS conflicts. To contribute to such an understanding, this study focuses on the analysis of IS conflicts. In so doing, it aims to identify various types of IS conflicts and to develop a framework that can be helpful in assessing these conflicts. To this end, we have conducted a meta-ethnographic study – that is, we synthesized earlier case studies in which IS conflicts are described. We purposefully selected 11 descriptions of IS conflicts and we analyzed the topics, contexts, and processes of these conflicts. Based on this analysis, we propose a two-dimensional framework of IS conflicts that leads to a categorization involving four IS conflict types: task; implementation process; structure; and value conflicts. Based on the conflicts that were studied, this paper also reveals that, in reality, many IS conflicts have a hybrid form and develop from one type to another over time.
Numerical evidence for two types of localized states in a two-dimensional disordered lattice
International Nuclear Information System (INIS)
Tit, N.; Kumar, N.
1992-06-01
We report results of our numerical calculations, based on the equation of motion method, of dc-electrical conductivity and of density of states up to 40x40 two-dimensional square lattices modelling a right-binding Hamiltonian for a binary (AB) compound, disordered by randomly distributed B vacancies up to 10%. Our results indicate strongly localized states away from band centers separated from the relatively weakly localized states toward midband. This is in qualitative agreement with the idea of a ''mobility edge'' separating exponentially localized states from the power-law localized states as suggested by the two-parameter scaling theory of Kaevh in two dimensions. (author). 7 refs, 4 figs
Huang, Huan; Yang, Ming; Lu, Cunyue; Xu, Liang; Zhuang, Xiaoqi; Meng, Fan
2013-10-01
Pulsatile left ventricular assist devices (LVADs) driven by electric motors have been widely accepted as a treatment of heart failure. Performance enhancement with computer assistance for this kind of LVAD has seldom been reported. In this article, a numerical method is proposed to assist the design of a cam-type pump. The method requires an integrated model of an LVAD system, consisting of a motor, a transmission mechanism, and a cardiovascular circulation. Performance indices, that is, outlet pressure, outlet flow, and pump efficiency, were used to select the best cam profile from six candidates. A prototype pump connected to a mock circulatory loop (MCL) was used to calibrate the friction coefficient of the cam groove and preliminarily evaluate modeling accuracy. In vitro experiments show that the mean outlet pressure and flow can be predicted with high accuracy by the model, and gross geometries of the measurements can also be reproduced. Simulation results demonstrate that as the total peripheral resistance (TPR) is fixed at 1.1 mm Hg.s/mL, the two-cycle 2/3-rise profile is the best. Compared with other profiles, the maximum increases of pressure and flow indices are 75 and 76%, respectively, and the maximum efficiency increase is over 51%. For different TPRs (0.5∼1.5 mm Hg.s/mL) and operation intervals (0.1∼0.4 s) in counterpulsation, the conclusion is also acceptable. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.
Numerical Analysis for un-baffled Mixing Tank Agitated by Two Types of Impellers
Directory of Open Access Journals (Sweden)
Ammar Ashour Akesh
2018-02-01
Full Text Available The effect of impeller flow type and rotation speed on the fluid in mixing tank design under standard configurations investigated to analyses the fluid velocity, turbulent intensity and path lines. In this theoretical study, the fluid motion inside the mixing tank was investigated by solving Navier-Stokes equation and standard k-ε turbulent model in 3-dimensions, for incompressible and turbulent flow. Two types of flow with three types of impellers were investigated, axial-flow with (Lightnin200 and generic impellers and radial-flow with (Rushton turbine. All impellers evaluated under rotation velocity variation between 10 – 115 rpm. The results showed a direct proportional relationship between the impeller and turbine rotation speed with the fluid velocity in mixing vessel. Also, this case matches with the turbulent intensity and path lines.
New type of radiation instrumentation system
International Nuclear Information System (INIS)
Matsuo, Keichi; Takaoka, Akira; Uranaka, Yasuo
2000-01-01
The Mitsubishi Electric Co., Ltd. developed a radiation instrumentation system introduced some recent techniques such as computation technique, network technique and so on into conventional radiation detection aiming at general market except power generation company. In a conventional system, a detector and an operation processing board was placed at a field and center, respectively, and a feeble pulse signal from the detector was transferred to the operation processing board. Then, on establishment of cables, detectors and operation processing board, it is essential to carry out engineering planning and field engineering conceiving on noise countermeasure. Noise resistance of the new type of radiation instrumentation system, not by adding operation processing function and network interface function into a detector unit in a field to transfer feeble signal, but by transferring testing result as a digital signal. And, noise removing function capable of selectively passing only signal pulse waveform from the detector to judge its signal waveform was also added to a detector unit in the field, to carry out a thoroughly removing noise. In addition, by connecting between each apparatus placed at the field with a network a system capable of reducing some cable engineering could be executed. Here were introduced on abstract of this new type of radiation instrumentation system and on noise removing function of its characteristics. (G.K.)
International Nuclear Information System (INIS)
Yamazawa, H.; Ohkura, T.; Iida, T.; Chino, M.; Nagai, H.
2003-01-01
Main functions of the Numerical Environment System (NES), as a part of the Information Technology Based Laboratory (ITBL) project implemented by Japan Atomic Energy Research Institute, became available for test use purposes although the development of the system is still underway. This system consists of numerical models of meteorology and atmospheric dispersion, database necessary for model simulations, post- and pre-processors such as data conversion and visualization, and a suite of system software which provide the users with system functions through a web page access. The system utilizes calculation servers such as vector- and scalar-parallel processors for numerical model execution, a EWS which serves as a hub of the system. This system provides users in the field of nuclear emergency preparedness and atmospheric environment with easy-to-use functions of atmospheric dispersion simulations including input meteorological data preparation and visualization of simulation results. The performance of numerical models in the system was examined with observation data of long-range transported radon-222. The models in the system reproduced quite well temporal variations in the observed radon-222 concentrations in air which were caused by changes in the meteorological field in the synoptic scale. By applying the NES models in combination with the idea of backward-in-time atmospheric dispersion simulation, seasonal shift of source areas of radon-222 in the eastern Asian regions affecting the concentrations in Japan was quantitatively illustrated. (authors)
A numerical study on the performance evaluation of ventilation systems for indoor radon reduction
Energy Technology Data Exchange (ETDEWEB)
Lee, Ji Eun; Park, Hoon Chae; Choi, Hang Seok; Cho, Seung Yeon; Jeong, Tae Young; Roh, Sung Cheoul [Yonsei University, Wonju (Korea, Republic of)
2016-03-15
Numerical simulations were conducted using computational fluid dynamics to evaluate the effect of ventilation conditions on radon ({sup 222}Rn) reduction performance in a residential building. The results indicate that at the same ventilation rate, a mechanical ventilation system is more effective in reducing indoor radon than a natural ventilation system. For the same ventilation type, the indoor radon concentration decreases as the ventilation rate increases. When the air change per hour (ACH) was 1, the indoor radon concentration was maintained at less than 100 Bq/m{sup 3}. However, when the ACH was lowered to 0.01, the average indoor radon concentration in several rooms exceeded 148 Bq/ m{sup 3}. The angle of the inflow air was found to affect the indoor air stream and consequently the distribution of the radon concentration. Even when the ACH was 1, the radon concentrations of some areas were higher than 100 Bq/m{sup 3} for inflow air angles of 5 .deg. and 175 .deg.
Numerical study of properties of many-dimensional soliton-type objects
International Nuclear Information System (INIS)
Makhankov, V.G.; Shvachka, A.B.
1980-01-01
A brief review of the dynamical properties of many-dimensional quasi-solitons studied by means of the computer simulation in the framework of the nonlinear classical field theory models is presented. It is shown that the types of soliton interactions are model independent for studied models
On a New Method for Computing the Numerical Solution of Systems of Nonlinear Equations
Directory of Open Access Journals (Sweden)
H. Montazeri
2012-01-01
Full Text Available We consider a system of nonlinear equations F(x=0. A new iterative method for solving this problem numerically is suggested. The analytical discussions of the method are provided to reveal its sixth order of convergence. A discussion on the efficiency index of the contribution with comparison to the other iterative methods is also given. Finally, numerical tests illustrate the theoretical aspects using the programming package Mathematica.
DEFF Research Database (Denmark)
Görke, Uwe Jens; Taron, Joshua; Singh, Ashok
2011-01-01
In this paper, conceptual and numerical modeling of coupled thermo-hydro-mechanical (THM) processes during CO 2 injection and storage is presented. The commonly used averaging procedure combining the Theory of Mixtures and the Concept of Volume Fractions serves as background for the complex porous...... mathematical models are of similar structure. Thus, the paper is mainly focused on a generic theoretical framework for the coupled processes under consideration. Within this context, CO 2 sequestration in georeservoirs of different type can be simulated (e.g., saline aquifers, (nearly) depleted hydrocarbon...... media approach presented here. Numerical models are based on a generalized formulation of the individual and overall balance equations for mass and momentum, as well as, in non-isothermal case, the energy balance equation. Within the framework of a standard Galerkin approach, the method of weighted...
International Nuclear Information System (INIS)
Vatin, E.; Guillou, J.; Tephany, F.; Trollat, C.
1993-08-01
This paper presents a study on the dynamic response of piping systems installed in the French 1300 MWe Nuclear Power Plants. Variations in pressure are generated by a multi-staged centrifugal pump mounted on the piping system and provide a dynamic excitation of the pipe. This type of dynamic loading has led to nozzle cracks for some of the pipes, whereas, for other installations, it has not be found detrimental. This study presents an explanation of the different dynamic behavior observed at the various plants. To this end, a numerical model, calibrated with on-site measurements, is impleted. (authors). 8 figs., 1 tab., 5 refs
Steam generating system in LMFBR type reactors
International Nuclear Information System (INIS)
Kurosawa, Katsutoshi.
1984-01-01
Purpose: To suppress the thermal shock loads to the structures of reactor system and secondary coolant system, for instance, upon plant trip accompanying turbine trip in the steam generation system of LMFBR type reactors. Constitution: Additional feedwater heater is disposed to the pipeway at the inlet of a steam generator in a steam generation system equipped with a closed loop extended from a steam generator by way of a gas-liquid separator, a turbine and a condensator to the steam generator. The separated water at high temperature and high pressure from a gas-liquid separator is heat exchanged with coolants flowing through the closed loop of the steam generation system in non-contact manner and, thereafter, introduced to a water reservoir tank. This can avoid the water to be fed at low temperature as it is to the steam generator, whereby the thermal shock loads to the structures of the reactor system and the secondary coolant system can be suppressed. (Moriyama, K.)
A Type System For Certified Runtime Type Analysis
2002-12-01
1999 ACM SIGPLAN International Conf. on Functional Pro- gramming (ICFP’99), pages 183–196. ACM Press, September 1999. [Min97] Yasuhiko Minamide. Full...lifting of type parameters. Technical report, RIMS, Kyoto University, 1997. [MMH96] Yasuhiko Minamide, Greg Morrisett, and Robert Harper. Typed
Sweilam, N. H.; Abou Hasan, M. M.
2017-05-01
In this paper, the weighted-average non-standard finite-difference (WANSFD) method is used to study numerically the general time-fractional nonlinear, one-dimensional problem of thermoelasticity. This model contains the standard system arising in thermoelasticity as a special case. The stability of the proposed method is analyzed by a procedure akin to the standard John von Neumann technique. Moreover, the accuracy of the proposed scheme is proved. Numerical results are presented graphically, which reveal that the WANSFD method is easy to implement, effective and convenient for solving the proposed system. The proposed method could also be easily extended to solve other systems of fractional partial differential equations.
Minakov, A. V.; Shebeleva, A. A.; Yagodnitsyna, A. A.; Kovalev, A. V.; Bilsky, A. V.
2017-09-01
The slow-flug regime in a mixture of castor and paraffin oils in a T-type microchannel with crosssectional dimensions of 200 × 400 μm has been studied by numerical and experimental methods. The domain of existence of the slow-flug regime in this system has been determined. Dependence of the paraffin-oil slug length on the ratio of flow rates of the mixture components is established. Comparison of the calculated and experimental data shows their good agreement.
Numerical simulation of a cabin ventilation subsystem in a space station oriented real-time system
Directory of Open Access Journals (Sweden)
Zezheng QIU
2017-12-01
Full Text Available An environment control and life support system (ECLSS is an important system in a space station. The ECLSS is a typical complex system, and the real-time simulation technology can help to accelerate its research process by using distributed hardware in a loop simulation system. An implicit fixed time step numerical integration method is recommended for a real-time simulation system with time-varying parameters. However, its computational efficiency is too low to satisfy the real-time data interaction, especially for the complex ECLSS system running on a PC cluster. The instability problem of an explicit method strongly limits its application in the ECLSS real-time simulation although it has a high computational efficiency. This paper proposes an improved numerical simulation method to overcome the instability problem based on the explicit Euler method. A temperature and humidity control subsystem (THCS is firstly established, and its numerical stability is analyzed by using the eigenvalue estimation theory. Furthermore, an adaptive operator is proposed to avoid the potential instability problem. The stability and accuracy of the proposed method are investigated carefully. Simulation results show that this proposed method can provide a good way for some complex time-variant systems to run their real-time simulation on a PC cluster. Keywords: Numerical integration method, Real-time simulation, Stability, THCS, Time-variant system
Bumgarner, Johnathan R; McCray, John E
2007-06-01
During operation of an onsite wastewater treatment system, a low-permeability biozone develops at the infiltrative surface (IS) during application of wastewater to soil. Inverse numerical-model simulations were used to estimate the biozone saturated hydraulic conductivity (K(biozone)) under variably saturated conditions for 29 wastewater infiltration test cells installed in a sandy loam field soil. Test cells employed two loading rates (4 and 8cm/day) and 3 IS designs: open chamber, gravel, and synthetic bundles. The ratio of K(biozone) to the saturated hydraulic conductivity of the natural soil (K(s)) was used to quantify the reductions in the IS hydraulic conductivity. A smaller value of K(biozone)/K(s,) reflects a greater reduction in hydraulic conductivity. The IS hydraulic conductivity was reduced by 1-3 orders of magnitude. The reduction in IS hydraulic conductivity was primarily influenced by wastewater loading rate and IS type and not by the K(s) of the native soil. The higher loading rate yielded greater reductions in IS hydraulic conductivity than the lower loading rate for bundle and gravel cells, but the difference was not statistically significant for chamber cells. Bundle and gravel cells exhibited a greater reduction in IS hydraulic conductivity than chamber cells at the higher loading rates, while the difference between gravel and bundle systems was not statistically significant. At the lower rate, bundle cells exhibited generally lower K(biozone)/K(s) values, but not at a statistically significant level, while gravel and chamber cells were statistically similar. Gravel cells exhibited the greatest variability in measured values, which may complicate design efforts based on K(biozone) evaluations for these systems. These results suggest that chamber systems may provide for a more robust design, particularly for high or variable wastewater infiltration rates.
Directory of Open Access Journals (Sweden)
Kasni Sumeru
2013-07-01
Full Text Available The present study describes a numerical approach for determining both the motive nozzle and constant-area diameters of an ejector as an expansion device, based on the cooling capacity of a split-type air-conditioner using R290 as refrigerant. Previous studies have shown that replacement of HCFC R22 with HC290 (propane in the air conditioner can improve the coefficient of performance (COP. The purpose of replacing the capillary tube with an ejector as an expansion device in a split-type air conditioner using HC290 is to further improve the COP. In developing the model, conservation laws of mass, momentum and energy equations were applied to each part of the ejector. The numerical results show that the motive nozzle diameter remains constant (1.03 mm under varying condenser temperatures, whereas the diameter of the constant-area decreases as the condenser temperature increases. It was also found that improvement of the COP can reach 32.90% at a condenser temperature of 55 °C. From the results mentioned above, it can be concluded that the use of an ejector can further improve the COP of a split-type air conditioner using HC290 as working fluid.
Numerical Thermodynamic Analysis of Two-Phase Solid-Liquid Abrasive Flow Polishing in U-Type Tube
Directory of Open Access Journals (Sweden)
Junye Li
2014-08-01
Full Text Available U-type tubes are widely used in military and civilian fields and the quality of the internal surface of their channel often determines the merits and performance of a machine in which they are incorporated. Abrasive flow polishing is an effective method for improving the channel surface quality of a U-type tube. Using the results of a numerical analysis of the thermodynamic energy balance equation of a two-phase solid-liquid flow, we carried out numerical simulations of the heat transfer and surface processing characteristics of a two-phase solid-liquid abrasive flow polishing of a U-type tube. The distribution cloud of the changes in the inlet turbulent kinetic energy, turbulence intensity, turbulent viscosity, and dynamic pressure near the wall of the tube were obtained. The relationships between the temperature and the turbulent kinetic energy, between the turbulent kinetic energy and the velocity, and between the temperature and the processing velocity were also determined to develop a theoretical basis for controlling the quality of abrasive flow polishing.
International Nuclear Information System (INIS)
Lee, J. H.; Park, I. S.; Ahmad, D.; Kim, D.; Kim, Y. C.; Ko, R. K.; Jeong, D. Y.
2012-01-01
The macroscopic magnetic behaviors of a type-II superconductor, such as the field- or the temperature-dependent magnetization, have been described by using critical state models. However, because the models are time-independent, the magnetic relaxation in a type-II superconductor cannot be described by them, and the time dependence of the magnetization can affect the field or the temperature-dependent magnetization curve described by the models. In order to avoid the time independence of critical state models, we try the numerical calculation used by Qin et al., who mainly calculated the temperature dependence of the ac susceptibility χ(T). Their calculation showed that the frequency-dependent χ(T) could be obtained by using the flux-creep equation. We calculated the field-dependent magnetization and magnetic relaxation by using a numerical method. The calculated field-dependent magnetization M(H) curves shows the shapes of a typical type-II superconductor. The calculated magnetic relaxation do not show a logarithmic decay of the magnetization, but the addition of a surface barrier to the relaxation calculation caused a clear logarithmic decay of the magnetization, producing a crossover at a mid-time. This means that the logarithmic magnetic relaxation is caused by not only flux creep but also a combination of flux creep and a surface barrier.
An impulsive predator-prey system with modified Leslie-Gower and Holling type II schemes
International Nuclear Information System (INIS)
Guo Hongjian; Song Xinyu
2008-01-01
An impulsive predator-prey system with modified Leslie-Gower and Holling-type II schemes is presented. By using the Floquet theory of impulsive equation and small amplitude perturbation method, the globally asymptotical stability of prey-free positive periodic solution and the permanence of system are discussed. The corresponding threshold conditions are obtained respectively. Finally, numerical simulations are given
Numerical Modeling of an Integrated Vehicle Fluids System Loop for Pressurizing a Cryogenic Tank
LeClair, A. C.; Hedayat, A.; Majumdar, A. K.
2017-01-01
This paper presents a numerical model of the pressurization loop of the Integrated Vehicle Fluids (IVF) system using the Generalized Fluid System Simulation Program (GFSSP). The IVF propulsion system, being developed by United Launch Alliance to reduce system weight and enhance reliability, uses boiloff propellants to drive thrusters for the reaction control system as well as to run internal combustion engines to develop power and drive compressors to pressurize propellant tanks. NASA Marshall Space Flight Center (MSFC) conducted tests to verify the functioning of the IVF system using a flight-like tank. GFSSP, a finite volume based flow network analysis software developed at MSFC, has been used to support the test program. This paper presents the simulation of three different test series, comparison of numerical prediction and test data and a novel method of presenting data in a dimensionless form. The paper also presents a methodology of implementing a compressor map in a system level code.
Numerical analysis of blast flow-field of baffle type muzzle brake
Energy Technology Data Exchange (ETDEWEB)
Kim, D.H. [Graduate School, Chungnam National University, Taejon (Korea); Ko, S. [Chungnam National University, Taejon (Korea)
1998-11-01
A three-dimensional unsteady, inviscid blast flow-field of a baffle type muzzle brake has been simulated by solving the Euler equation. The blast flow-field includes the effect of the free air blast, precursor blast flow and the propellant blast gas flow. Chimera grid scheme was used to generate 9 multi-block volume grids for the complex geometry. The evolution of the blast flow-field is presented by showing the contours of pressure, density and Mach number for certain time step. The comparison of the calculated and measured peak pressures on the surfaces of the muzzle brake is also presented. (author). 4 refs., 5 figs., 1 tab.
Numerical study of a DRAKON-type closed magnetic configuration with a spatial axis
International Nuclear Information System (INIS)
Kondakov, V.V.; Perelygin, S.F.; Smirnov, V.M.
2000-01-01
The calculational results on the magnetic power lines and trajectories of charged particles in the magnetic system of the DRAKON plasma trap and its element, exactly curvilinear element (CLEL) with magnetic plugs are presented. The dimensions in the area of the inlet of electrons into the CLEL for creation of a plasma-beam discharge are calculated. It is confirmed that in paraxial approximation the magnetic power lines and trajectories of separate flight-through particles during multiple circumvention of the DRAKON facility form the system of toroidal surfaces with circular cross sections embedded into each other. Dependences of the drift surface shear, relative to the magnetic ones on the spiral winding, are determined for the DRAKON system with the spiral CLEL [ru
Numerical and experimental analysis of a horizontal ground-coupled heat pump system
Energy Technology Data Exchange (ETDEWEB)
Esen, Hikmet; Esen, Mehmet [Department of Mechanical Education, Faculty of Technical Education, University of Firat, 23119 Elazig (Turkey); Inalli, Mustafa [Department of Mechanical Engineering, Faculty of Engineering, University of Firat, 23119 Elazig (Turkey)
2007-03-15
The main objective of this work is to evaluate a heat pump system using the ground as a source of heat. A ground-coupled heat pump (GCHP) system has been installed and tested at the test room, University of Firat, Elazig, Turkey. Results obtained during experimental testing are presented and discussed here. The coefficient of performance (COP{sub sys}) of the GCHP system is determined from the measured data. A numerical model of heat transfer in the ground was developed for determining the temperature distribution in the vicinity of the pipe. The finite difference approximation is used for numerical analysis. It is observed that the numerical results agree with the experimental results. (author) (author)
Mathematical and numerical analysis of hyper-elastic systems and introduction of plasticity
International Nuclear Information System (INIS)
Kluth, G.
2008-12-01
The goal is to model mathematically and numerically the dynamic phenomenons for solids in finite plasticity. We suggest a model that we call hyper-elasto-plastic based on hyper-elastic systems of conservation laws and on the use of an equation of state that we have constructed so as to achieve the plastic yield criterion of Von Mises. This model gives exact (analytic) solutions with shock split to flyer-plate experiments. The mathematical analysis of this model is done (hyperbolicity, characteristic fields, involutions and entropy). In the numerical part, we give 1D and 2D Lagrangian schemes which satisfy an entropy criterion. Moreover, thanks to a special discretization of the equations on deformation gradient, we satisfy some discrete involutions. In this work, the degeneracy of the solid model into hydrodynamic models is studied at the continuous level, and achieved at the numerical one. On different problems, we show the validity of our model and our numerical schemes. (author)
Recycling systems for BWR type reactors
International Nuclear Information System (INIS)
Takagi, Akio; Yamamoto, Fumiaki; Fukumoto, Ryuji.
1986-01-01
Purpose: To stabilize the coolant flowing characteristics and reactor core reactivity. Constitution: The recycling system in a BWR type reactor comprises a recycling pump disposed to the outside of a reactor pressure vessel, a ring header connected to the recycling pump through main pipe ways, and a plurality of pipes branched from and connected with the ring header and connected to a plurality of jet pumps within the pressure vessel. Then, by making the diameter for the pipeways of each of the branched pipes different from each other, the effective cross-sectional area is varied to thereby average the coolant flow rate supplied to each of the jet pumps. (Seki, T.)
Primary coolant system of BWR type reactor
International Nuclear Information System (INIS)
Ibe, Hidefumi; Takahashi, Masanori; Aoki, Yasuko
1997-01-01
The present invention provides a water quality control system for preventing corrosion and for extending working life of structural materials of a BWR-type reactor. Namely, a sensor group 1 and a sensor group 2 are disposed at different positions such as in a feedwater system, a recycling system, main steam pipes, and a pressure vessel, respectively. Each sensor group can record and generate alarms independently. The sensor group 1 for usual monitoring is connected to a calculation device by way of a switch to confirm that the monitored values are within a proper range by the injection of a water quality moderating agent. The sensor group 2 is caused to stand alone or connected with the calculation device by way of a switch optionally. When abnormality should occur in the sensor group 1, the sensor group 2 determines the limit for the increase/decrease of controlling amount of the moderating agent at a portion where the conditions are changed to the most severe direction by using data base. The moderating agent is injected and controlled based on the controlling amount. The system of the present invention can optionally cope with a new sensor and determination for new water quality standards. Then the evaluation/control accuracy of the entire system can be improved while covering up the errors of each sensor. (I.S.)
Numerical study of the thermo-hydraulic behavior for the Candu type fuel channel
International Nuclear Information System (INIS)
Lazaro, Pavel Gabriel; Balas Ghizdeanu, Elena Nineta
2008-01-01
Candu type reactors use fuel channel in a horizontal lattice. The fuel bundles are positioned in two Zircaloy tubes: the pressure tube surrounded by calandria tube. Inside the pressure tube the coolant heavy water flows. The coolant reaches high temperatures and pressures. Due to irregular neutron spatial distribution, the fuel channel stress differs from one channel to other. In one improbable event of severe accident, the fuel channel behaves differently according to its normal function history. Over the years, there have been many research projects trying to analyze thermal hydraulic performance of the design and to add some operational improvements in order to achieve an efficient thermal hydraulic distribution. This paper discusses the thermo hydraulic behavior (influence of the temperature and velocity distribution) of the most solicited channel, simulated with Fluent 6.X. Code. Moreover it will be commented the results obtained using different models and mesh applied. (authors)
Numerical analysis of the flow around the Bach-type Savonius wind turbine
International Nuclear Information System (INIS)
Kacprzak, K; Sobczak, K
2014-01-01
The performance of the Bach-type Savonius wind turbine with a constant cross-section is examined by means of quasi 2D and 3D flow predictions obtained from ANSYS CFX. Simulations were performed in a way allowing for a comparison with the wind tunnel data presented by Kamoji et al. The comparison with the experiment has revealed that 2D solutions give much higher deviation from the reference data than the 3D ones, which guarantees a good solution quality. It can be stated that even simplified (lack of laminar-turbulence transition modelling and a coarser mesh) 3D simulations can yield more accurate results than complex 2D solutions for turbines with a low aspect ratio. The paper also presents a systematic analysis of the most characteristic flow structures which are identified in the rotor.
Numerical analysis of the flow around the Bach-type Savonius wind turbine
Kacprzak, K.; Sobczak, K.
2014-08-01
The performance of the Bach-type Savonius wind turbine with a constant cross-section is examined by means of quasi 2D and 3D flow predictions obtained from ANSYS CFX. Simulations were performed in a way allowing for a comparison with the wind tunnel data presented by Kamoji et al. The comparison with the experiment has revealed that 2D solutions give much higher deviation from the reference data than the 3D ones, which guarantees a good solution quality. It can be stated that even simplified (lack of laminar-turbulence transition modelling and a coarser mesh) 3D simulations can yield more accurate results than complex 2D solutions for turbines with a low aspect ratio. The paper also presents a systematic analysis of the most characteristic flow structures which are identified in the rotor.
Optimum placement of condensing units of split-type air-conditioners by numerical simulation
Energy Technology Data Exchange (ETDEWEB)
Avara, Abdollah; Daneshgar, Ehsan [Mechanical Engineering Department, Persian Gulf University, Bushehr (Iran, Islamic Republic of)
2008-07-01
Split-type air-conditioners used in residential or office buildings often have the outdoor condensing units installed at the sidewalls or on the roofs. Installation distance from the supporting wall for the first group and the height of installation for the second group are two factors that affect the condenser efficiency. In this study, a CFD code is used to calculate the effect of distance from the supporting wall on the entrance air temperature and on the on-coil temperature of condenser installed between two walls. In the case of condenser installed on the roof, the effect of installation height of the condenser from the finished roof on on-coil temperature is investigated and the minimum recommended height of installation is determined. (author)
International Nuclear Information System (INIS)
Hoehne, T.; Rhode, U.
2000-01-01
The VVER-440 (440 MW) V-230 was considered for analyzing the flow field and mixing processes. The V-230 has no elliptical sieve plate in the lower plenum. Previously, the 3D flow distribution in the downcomer and the lower plenum of the VVER-440 reactor have been calculated by means of the CFD code CFX-4 for operational conditions. The CFX-calculations were compared with the experimental data and the analytical mixing model. In this paper, CFD calculations for the start-up of the first main coolant pump in a VVER-440 type reactor are reported about. This scenario is important in case that there is a plug of lower borated water in one of the primary coolant loops. (orig.)
NUMERICAL SIMULATION OF SOLAR MICROFLARES IN A CANOPY-TYPE MAGNETIC CONFIGURATION
International Nuclear Information System (INIS)
Jiang, R.-L.; Fang, C.; Chen, P.-F.
2012-01-01
Microflares are small activities in the solar low atmosphere; some are in the low corona while others are in the chromosphere. Observations show that some of the microflares are triggered by magnetic reconnection between the emerging flux and a pre-existing background magnetic field. We perform 2.5-dimensional, compressible, resistive magnetohydrodynamic simulations of the magnetic reconnection with gravity considered. The background magnetic field is a canopy-type configuration that is rooted at the boundary of the solar supergranule. By changing the bottom boundary conditions in the simulation, a new magnetic flux emerges at the center of the supergranule and reconnects with the canopy-type magnetic field. We successfully simulate the coronal and chromospheric microflares whose current sheets are located at the corona and the chromosphere, respectively. The microflare with a coronal origin has a larger size and a higher temperature enhancement than the microflare with a chromospheric origin. In the microflares with coronal origins, we also found a hot jet (∼1.8 × 10 6 K), which is probably related to the observational extreme ultraviolet or soft X-ray jets, and a cold jet (∼10 4 K), which is similar to the observational Hα/Ca surges. However, there is only a Hα/Ca bright point in the microflares that have chromospheric origins. The study of parameter dependence shows that the size and strength of the emerging magnetic flux are the key parameters that determine the height of the reconnection location, and they further determine the different observational features of the microflares.
Level controlling system in BWR type reactors
International Nuclear Information System (INIS)
Joge, Toshio; Higashigawa, Yuichi; Oomori, Takashi.
1981-01-01
Purpose: To reasonably attain fully automatic water level control in the core of BWR type nuclear power plants. Constitution: A feedwater flow regulation valve for reactor operation and a feedwater flow regulation valve for starting are provided at the outlet of a motor-driven feedwater pump in a feedwater system, and these valves are controlled by a feedwater flow rate controller. While on the other hand, a damp valve for reactor clean up system is controlled either in ''computer'' mode or in ''manual'' mode selected by a master switch, that is, controlled from a computer or the ON-OFF switch of the master switch by way of a valve control analog memory and a turn-over switch. In this way, the water level in the nuclear reactor can be controlled in a fully automatic manner reasonably at the starting up and shutdown of the plant to thereby provide man power saving. (Seki, T.)
A numerical scheme for optimal transition paths of stochastic chemical kinetic systems
International Nuclear Information System (INIS)
Liu Di
2008-01-01
We present a new framework for finding the optimal transition paths of metastable stochastic chemical kinetic systems with large system size. The optimal transition paths are identified to be the most probable paths according to the Large Deviation Theory of stochastic processes. Dynamical equations for the optimal transition paths are derived using the variational principle. A modified Minimum Action Method (MAM) is proposed as a numerical scheme to solve the optimal transition paths. Applications to Gene Regulatory Networks such as the toggle switch model and the Lactose Operon Model in Escherichia coli are presented as numerical examples
Ely, D. Matthew; Burns, Erick R.; Morgan, David S.; Vaccaro, John J.
2014-01-01
A three-dimensional numerical model of groundwater flow was constructed for the Columbia Plateau Regional Aquifer System (CPRAS), Idaho, Oregon, and Washington, to evaluate and test the conceptual model of the system and to evaluate groundwater availability. The model described in this report can be used as a tool by water-resource managers and other stakeholders to quantitatively evaluate proposed alternative management strategies and assess the long‑term availability of groundwater. The numerical simulation of groundwater flow in the CPRAS was completed with support from the Groundwater Resources Program of the U.S. Geological Survey Office of Groundwater.
A numeric-analytic method for approximating the chaotic Chen system
International Nuclear Information System (INIS)
Mossa Al-sawalha, M.; Noorani, M.S.M.
2009-01-01
The epitome of this paper centers on the application of the differential transformation method (DTM) the renowned Chen system which is described as a three-dimensional system of ODEs with quadratic nonlinearities. Numerical comparisons are made between the DTM and the classical fourth-order Runge-Kutta method (RK4). Our work showcases the precision of the DTM as the Chen system transforms from a non-chaotic system to a chaotic one. Since the Lyapunov exponent for this system is much higher compared to other chaotic systems, we shall highlight the difficulties of the simulations with respect to its accuracy. We wrap up our investigations to reveal that this direct symbolic-numeric scheme is effective and accurate.
Evidence for two numerical systems that are similar in humans and guppies.
Directory of Open Access Journals (Sweden)
Christian Agrillo
Full Text Available BACKGROUND: Humans and non-human animals share an approximate non-verbal system for representing and comparing numerosities that has no upper limit and for which accuracy is dependent on the numerical ratio. Current evidence indicates that the mechanism for keeping track of individual objects can also be used for numerical purposes; if so, its accuracy will be independent of numerical ratio, but its capacity is limited to the number of items that can be tracked, about four. There is, however, growing controversy as to whether two separate number systems are present in other vertebrate species. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we compared the ability of undergraduate students and guppies to discriminate the same numerical ratios, both within and beyond the small number range. In both students and fish the performance was ratio-independent for the numbers 1-4, while it steadily increased with numerical distance when larger numbers were presented. CONCLUSIONS/SIGNIFICANCE: Our results suggest that two distinct systems underlie quantity discrimination in both humans and fish, implying that the building blocks of uniquely human mathematical abilities may be evolutionarily ancient, dating back to before the divergence of bony fish and tetrapod lineages.
Modelling of cardiovascular system: development of a hybrid (numerical-physical) model.
Ferrari, G; Kozarski, M; De Lazzari, C; Górczyńska, K; Mimmo, R; Guaragno, M; Tosti, G; Darowski, M
2003-12-01
Physical models of the circulation are used for research, training and for testing of implantable active and passive circulatory prosthetic and assistance devices. However, in comparison with numerical models, they are rigid and expensive. To overcome these limitations, we have developed a model of the circulation based on the merging of a lumped parameter physical model into a numerical one (producing therefore a hybrid). The physical model is limited to the barest essentials and, in this application, developed to test the principle, it is a windkessel representing the systemic arterial tree. The lumped parameters numerical model was developed in LabVIEW environment and represents pulmonary and systemic circulation (except the systemic arterial tree). Based on the equivalence between hydraulic and electrical circuits, this prototype was developed connecting the numerical model to an electrical circuit--the physical model. This specific solution is valid mainly educationally but permits the development of software and the verification of preliminary results without using cumbersome hydraulic circuits. The interfaces between numerical and electrical circuits are set up by a voltage controlled current generator and a voltage controlled voltage generator. The behavior of the model is analyzed based on the ventricular pressure-volume loops and on the time course of arterial and ventricular pressures and flow in different circulatory conditions. The model can represent hemodynamic relationships in different ventricular and circulatory conditions.
Numerical Coupling and Simulation of Point-Mass System with the Turbulent Fluid Flow
Gao, Zheng
A computational framework that combines the Eulerian description of the turbulence field with a Lagrangian point-mass ensemble is proposed in this dissertation. Depending on the Reynolds number, the turbulence field is simulated using Direct Numerical Simulation (DNS) or eddy viscosity model. In the meanwhile, the particle system, such as spring-mass system and cloud droplets, are modeled using the ordinary differential system, which is stiff and hence poses a challenge to the stability of the entire system. This computational framework is applied to the numerical study of parachute deceleration and cloud microphysics. These two distinct problems can be uniformly modeled with Partial Differential Equations (PDEs) and Ordinary Differential Equations (ODEs), and numerically solved in the same framework. For the parachute simulation, a novel porosity model is proposed to simulate the porous effects of the parachute canopy. This model is easy to implement with the projection method and is able to reproduce Darcy's law observed in the experiment. Moreover, the impacts of using different versions of k-epsilon turbulence model in the parachute simulation have been investigated and conclude that the standard and Re-Normalisation Group (RNG) model may overestimate the turbulence effects when Reynolds number is small while the Realizable model has a consistent performance with both large and small Reynolds number. For another application, cloud microphysics, the cloud entrainment-mixing problem is studied in the same numerical framework. Three sets of DNS are carried out with both decaying and forced turbulence. The numerical result suggests a new way parameterize the cloud mixing degree using the dynamical measures. The numerical experiments also verify the negative relationship between the droplets number concentration and the vorticity field. The results imply that the gravity has fewer impacts on the forced turbulence than the decaying turbulence. In summary, the
Analysis and synthesis for interval type-2 fuzzy-model-based systems
Li, Hongyi; Lam, Hak-Keung; Gao, Yabin
2016-01-01
This book develops a set of reference methods capable of modeling uncertainties existing in membership functions, and analyzing and synthesizing the interval type-2 fuzzy systems with desired performances. It also provides numerous simulation results for various examples, which fill certain gaps in this area of research and may serve as benchmark solutions for the readers. Interval type-2 T-S fuzzy models provide a convenient and flexible method for analysis and synthesis of complex nonlinear systems with uncertainties.
Directory of Open Access Journals (Sweden)
Yuji Ohya
2016-12-01
Full Text Available A new type of solar tower was developed through laboratory experiments and numerical analyses. The solar tower mainly consists of three components. The transparent collector area is an aboveground glass roof, with increasing height toward the center. Attached to the center of the inside of the collector is a vertical tower within which a wind turbine is mounted at the lower entry to the tower. When solar radiation heats the ground through the glass roof, ascending warm air is guided to the center and into the tower. A solar tower that can generate electricity using a simple structure that enables easy and less costly maintenance has considerable advantages. However, conversion efficiency from sunshine energy to mechanical turbine energy is very low. Aiming to improve this efficiency, the research project developed a diffuser-type tower instead of a cylindrical tower, and investigated a suitable diffuser shape for practical use. After changing the tower height and diffuser open angle, with a temperature difference between the ambient air aloft and within the collector, various diffuser tower shapes were tested by laboratory experiments and numerical analyses. As a result, it was found that a diffuser tower with a semi-open angle of 4° is an optimal shape, producing the fastest updraft at each temperature difference in both the laboratory experiments and numerical analyses. The relationships between thermal updraft speed and temperature difference and/or tower height were confirmed. It was found that the thermal updraft velocity is proportional to the square root of the tower height and/or temperature difference.
International Nuclear Information System (INIS)
Chepe P, M.; Xolocostli M, J. V.; Gomez T, A. M.; Del Valle G, E.
2015-09-01
The deterministic transport codes for analysis of nuclear reactors have been used for several years already, these codes have evolved in terms of the methodology used and the degree of accuracy, because at the present time has more computer power. In this paper, the transport code used considers the classical technique of multi-group for discretization energy, for space discretization uses the nodal methods, while for the angular discretization the discrete ordinates method is used; so that presents the development and implementation of a set of numerical quadratures of SQ N type symmetrical with the same weight for each angular direction and these are compared with the quadratures of EQ N type. The two sets of numerical quadratures were implemented in the program AZTRAN to a problem with isotropic medium in XYZ geometry, in steady state using the nodal method RTN-0 (Raviart-Thomas-Nedelec). The analyzed results correspond to the effective multiplication factor k eff and neutron angular flux with approximations from S 4 to S 16 . (Author)
Direct numerical simulations of type Ia supernovae flames II: The Rayleigh-Taylor instability
International Nuclear Information System (INIS)
Bell, J.B.; Day, M.S.; Rendleman, C.A.; Woosley, S.E.; Zingale, M.
2004-01-01
A Type Ia supernova explosion likely begins as a nuclear runaway near the center of a carbon-oxygen white dwarf. The outward propagating flame is unstable to the Landau-Darrieus, Rayleigh-Taylor, and Kelvin-Helmholtz instabilities, which serve to accelerate it to a large fraction of the speed of sound. We investigate the Rayleigh-Taylor unstable flame at the transition from the flamelet regime to the distributed-burning regime, around densities of 10e7 gm/cc, through detailed, fully resolved simulations. A low Mach number, adaptive mesh hydrodynamics code is used to achieve the necessary resolution and long time scales. As the density is varied, we see a fundamental change in the character of the burning--at the low end of the density range the Rayleigh-Taylor instability dominates the burning, whereas at the high end the burning suppresses the instability. In all cases, significant acceleration of the flame is observed, limited only by the size of the domain we are able to study. We discuss the implications of these results on the potential for a deflagration to detonation transition
International Nuclear Information System (INIS)
Kalogiratou, Z.; Monovasilis, Th.; Psihoyios, G.; Simos, T.E.
2014-01-01
In this work we review single step methods of the Runge–Kutta type with special properties. Among them are methods specially tuned to integrate problems that exhibit a pronounced oscillatory character and such problems arise often in celestial mechanics and quantum mechanics. Symplectic methods, exponentially and trigonometrically fitted methods, minimum phase-lag and phase-fitted methods are presented. These are Runge–Kutta, Runge–Kutta–Nyström and Partitioned Runge–Kutta methods. The theory of constructing such methods is given as well as several specific methods. In order to present the performance of the methods we have tested 58 methods from all categories. We consider the two dimensional harmonic oscillator, the two body problem, the pendulum problem and the orbital problem studied by Stiefel and Bettis. Also we have tested the methods on the computation of the eigenvalues of the one dimensional time independent Schrödinger equation with the harmonic oscillator, the doubly anharmonic oscillator and the exponential potentials
Numerical analysis of coolant mixing in the pressure vessel of WWER-440 type nuclear reactors
International Nuclear Information System (INIS)
Boros, I.; Aszodi, A.
2003-01-01
The precise description of the coolant mixing processes taking place in the reactor pressure vessel (RPV) of pressurized water nuclear reactors has an essential importance during power operation, as well as in case of incidental or accidental conditions. In this paper the detailed CFD model of the pressure vessel of a WWER-440 type reactor and calculations performed with this RPV model are presented. The CFD model of the pressure vessel contains all the important internal structural elements of the RPV. Sensitivity study on the effect of these elements was also carried out. Both steady-state and transient calculation were performed using the CFD code CFX-5.5.1. The results of the steady-state calculations give the so called mixing factors, i.e. the effect of each single primary loop at the core inlet. The mixing factors can be given for nominal circumstances (i.e. all main coolant pumps are working) or in case of less than six working MCPs. In order to validate the model the calculated mixing factors are compared with the values measured in the Paks NPP (Authors)
One language, two number-word systems and many problems: numerical cognition in the Czech language.
Pixner, S; Zuber, J; Heřmanová, V; Kaufmann, L; Nuerk, H-C; Moeller, K
2011-01-01
Comparing numerical performance between different languages does not only mean comparing different number-word systems, but also implies a comparison of differences regarding culture or educational systems. The Czech language provides the remarkable opportunity to disentangle this confound as there exist two different number-word systems within the same language: for instance, "25" can be either coded in non-inverted order "dvadsetpät" [twenty-five] or in inverted order "pätadvadset" [five-and-twenty]. To investigate the influence of the number-word system on basic numerical processing within one culture, 7-year-old Czech-speaking children had to perform a transcoding task (i.e., writing Arabic numbers to dictation) in both number-word systems. The observed error pattern clearly indicated that the structure of the number-word system determined transcoding performance reliably: In the inverted number-word system about half of all errors were inversion-related. In contrast, hardly any inversion-related errors occurred in the non-inverted number-word system. We conclude that the development of numerical cognition does not only depend on cultural or educational differences, but is indeed related to the structure and transparency of a given number-word system. Copyright © 2011 Elsevier Ltd. All rights reserved.
Researching on YH100 Numerical Control Servo Press Hydraulic Control System and Control Algorithm
Directory of Open Access Journals (Sweden)
Kai LI
2014-09-01
Full Text Available In order to study the numerical control (NC servo press hydraulic control system and its control algorithm. The numerical control servo press performance and control principle of hydraulic control system are analyzed. According to the flow equation of the hydraulic control valve, hydraulic cylinder flow continuity equation and the force balance equation of the hydraulic cylinder with load press, the mathematical model of hydraulic control system is established. And the servo press hydraulic system transfer function is deduced. Introducing the suitable immune particle swarm control algorithm for servo press hydraulic system, and the control system block diagram is established. Immune algorithm is used to optimize new control parameters of the system and adopt the new optimization results to optimize the system simulation. The simulation result shows that the hydraulic system’s transition time controlled by the immune particle swarm algorithm is shorter than traditional ones, and the control performance is obviously improved. Finally it can be concluded that immune particle swarm PID control have these characteristics such as quickness, stability and accuracy. Applying this principle into application, the obtained YH100 numerical control servo press hydraulic control system meets the requirement.
Lan, C. Edward; Ge, Fuying
1989-01-01
Control system design for general nonlinear flight dynamic models is considered through numerical simulation. The design is accomplished through a numerical optimizer coupled with analysis of flight dynamic equations. The general flight dynamic equations are numerically integrated and dynamic characteristics are then identified from the dynamic response. The design variables are determined iteratively by the optimizer to optimize a prescribed objective function which is related to desired dynamic characteristics. Generality of the method allows nonlinear effects to aerodynamics and dynamic coupling to be considered in the design process. To demonstrate the method, nonlinear simulation models for an F-5A and an F-16 configurations are used to design dampers to satisfy specifications on flying qualities and control systems to prevent departure. The results indicate that the present method is simple in formulation and effective in satisfying the design objectives.
Numerical models of protoneutron stars and type-II supernovae - recent developments
Energy Technology Data Exchange (ETDEWEB)
Janka, H T [Max-Planck-Institut fuer Astrophysik, Garching (Germany)
1996-11-01
The results of recent multi-dimensional simulations of type-II supernovae are reviewed. They show that convective instabilities in the collapsed stellar core might play an important role already during the first second after the formation of the supernovae shock. Convectively unstable situations occur below and near the neutrinosphere as well as in the neutrino-heated region between the nascent neutron star and the supernova shock after the latter has stalled at a radiums of typically 100-200 km. While convective overturn in the layer of neutrino energy deposition clearly helps the explosion to develop and potentially provides an explanation of strong mantle and envelope mixing, asphericities, and non-uniform {sup 56}Ni distribution observed in supernova SN 1987A, its presence and importance depends on the strength of the neutrino heating and thus on the size of the neutrino fluxes from the neutrino star. Convection in the hot-bubble region can only be developed if the growth timescale of the instabilities and the heating timescale are both shorter than the accretion timescale of the matter advected through the stagnant shock. For too small neutrino luminosities this requirement is not fulfilled and convective activity cannot develop, leading to very weak explosions or even fizzling models, just as in the one-dimensional situations. Convectively enhanced neutrino luminosities from the protoneutron star can therefore provide an essential condition for the explosion of the star. Very recent two-dimensional, self-consistent, general relativistic simulations of the cooling of a newly-formed neutron star demonstrate and confirm the possibility that Ledoux convection, driven by negative lepton number and entropy gradients, may encompass the whole protoneutron star within less than one second and can lead to an increase of the neutrino fluxes by up to a factor of two. (author) 9 figs., refs.
Numerical study of the thermal behaviour of two types of packages exposed to long duration fires
International Nuclear Information System (INIS)
Doare, O.; Armingaud, F.; Sert, G.; Issard, H.
2004-01-01
The thermal behaviour of two types of package exposed to long duration fires is studied. The TN trademark 12/2A and TN trademark 28VT packages, respectively used for spent fuel and vitrified waste transports, are modelled. Three-dimensional meshes are used. Attention was paid to the model of the thermal protective resin of the packages because of its complex thermal behaviour. During heating several endothermic reactions occur: water vapour is produced and a part of it diffuses though the resin and condensates on the cold parts of resin, increasing the global heat transfer within the material. The other part of the water vapour exits the package by fusible holes. The thermal characteristics of these reactions have been established thanks to specific tests performed in a laboratory. A model taking into account all these phenomena was developed and integrated to the global thermal model of the packages in order to simulate the thermal behaviour of the packages exposed to long duration fires. Four fire temperatures were considered and, for each of them, the maximum fire duration that packages can withstand without activity release was calculated. The results show safety margins regarding the IAEA regulatory thermal test (800 C-30 min). The use of the complex model of resin led to calculate safety margins about 40% greater than those calculated with a model of resin taking only conduction into account. The results were used to prepare a guideline for safety assessment in emergency situations involving fire. This emergency tool provides safety limits for containment according to fire duration, fire temperature, package heat power and ambient temperature
Atmospheric models in the numerical simulation system (SPEEDI-MP) for environmental studies
International Nuclear Information System (INIS)
Nagai, Haruyasu; Terada, Hiroaki
2007-01-01
As a nuclear emergency response system, numerical models to predict the atmospheric dispersion of radionuclides have been developed at Japan Atomic Energy Agency (JAEA). Evolving these models by incorporating new schemes for physical processes and up-to-date computational technologies, a numerical simulation system, which consists of dynamical models and material transport models for the atmospheric, terrestrial, and oceanic environments, has been constructed to apply for various environmental studies. In this system, the combination of a non-hydrostatic atmospheric dynamic model and Lagrangian particle dispersion model is used for the emergency response system. The utilization of detailed meteorological field by the atmospheric model improves the model performance for diffusion and deposition calculations. It also calculates a large area domain with coarse resolution and local area domain with high resolution simultaneously. The performance of new model system was evaluated using measurements of surface deposition of 137 Cs over Europe during the Chernobyl accident. (author)
Directory of Open Access Journals (Sweden)
YaoHan Chen
Full Text Available The water spray systems are effective protection systems in the confined or unconfined spaces to avoid the damage to building structures since the high temperature when fires occur. NFPA 15 and 502 have suggested respectively that the factories or vehicle tunnels install water spray systems to protect the machinery and structures. This study discussed the cooling effect of water spray systems in experimental and numerical analyses. The actual combustion of woods were compared with the numerical simulations. The results showed that although the flame continued, the cooling effects by water spraying process within 120 seconds were obvious. The results also indicated that the simulation results of the fifth version Fire Dynamics Simulator (FDS overestimated the space temperature before water spraying in the case of the same water spray system.
A new type of simplified fuzzy rule-based system
Angelov, Plamen; Yager, Ronald
2012-02-01
Over the last quarter of a century, two types of fuzzy rule-based (FRB) systems dominated, namely Mamdani and Takagi-Sugeno type. They use the same type of scalar fuzzy sets defined per input variable in their antecedent part which are aggregated at the inference stage by t-norms or co-norms representing logical AND/OR operations. In this paper, we propose a significantly simplified alternative to define the antecedent part of FRB systems by data Clouds and density distribution. This new type of FRB systems goes further in the conceptual and computational simplification while preserving the best features (flexibility, modularity, and human intelligibility) of its predecessors. The proposed concept offers alternative non-parametric form of the rules antecedents, which fully reflects the real data distribution and does not require any explicit aggregation operations and scalar membership functions to be imposed. Instead, it derives the fuzzy membership of a particular data sample to a Cloud by the data density distribution of the data associated with that Cloud. Contrast this to the clustering which is parametric data space decomposition/partitioning where the fuzzy membership to a cluster is measured by the distance to the cluster centre/prototype ignoring all the data that form that cluster or approximating their distribution. The proposed new approach takes into account fully and exactly the spatial distribution and similarity of all the real data by proposing an innovative and much simplified form of the antecedent part. In this paper, we provide several numerical examples aiming to illustrate the concept.
Directory of Open Access Journals (Sweden)
Knyazheva Yu. V.
2014-06-01
Full Text Available The market economy causes need of development of the economic analysis first of all at microlevel, that is at the level of the separate enterprises as the enterprises are basis for market economy. Therefore improvement of the queuing system trading enterprise is an important economic problem. Analytical solutions of problems of the mass servicing are in described the theory, don’t correspond to real operating conditions of the queuing systems. Therefore in this article optimization of customer service process and improvement of settlement and cash service system trading enterprise are made by means of numerical statistical simulation of the queuing system trading enterprise. The article describe integrated statistical numerical simulation model of queuing systems trading enterprise working in nonstationary conditions with reference to different distribution laws of customers input stream. This model takes account of various behavior customers output stream, includes checkout service model which takes account of cashier rate of working, also this model includes staff motivation model, profit earning and profit optimization models that take into account possible revenue and costs. The created statistical numerical simulation model of queuing systems trading enterprise, at its realization in the suitable software environment, allows to perform optimization of the most important parameters of system. And when developing the convenient user interface, this model can be a component of support decision-making system for rationalization of organizational structure and for management optimization by trading enterprise.
Siegler, Robert S.; Braithwaite, David W.
2016-01-01
In this review, we attempt to integrate two crucial aspects of numerical development: learning the magnitudes of individual numbers and learning arithmetic. Numerical magnitude development involves gaining increasingly precise knowledge of increasing ranges and types of numbers: from non-symbolic to small symbolic numbers, from smaller to larger…
Scotch, Matthew; Parmanto, Bambang
2006-01-01
The development of numerical-spatial routines is frequently required to solve complex community health problems. Community health assessment (CHA) professionals who use information technology need a complete system that is capable of supporting the development of numerical-spatial routines. Currently, there is no decision support system (DSS) that is effectively able to accomplish this task as the majority of public health geospatial information systems (GIS) are based on traditional (relational) database architecture. On-Line Analytical Processing (OLAP) is a multidimensional data warehouse technique that is commonly used as a decision support system in standard industry. OLAP alone is not sufficient for solving numerical-spatial problems that frequently occur in CHA research. Coupling it with GIS technology offers the potential for a very powerful and useful system. A community health OLAP cube was created by integrating health and population data from various sources. OLAP and GIS technologies were then combined to develop the Spatial OLAP Visualization and Analysis Tool (SOVAT). The synergy of numerical and spatial environments within SOVAT is shown through an elaborate and easy-to-use drag and drop and direct manipulation graphical user interface (GUI). Community health problem-solving examples (routines) using SOVAT are shown through a series of screen shots. The impact of the difference between SOVAT and existing GIS public health applications can be seen by considering the numerical-spatial problem-solving examples. These examples are facilitated using OLAP-GIS functions. These functions can be mimicked in existing GIS public applications, but their performance and system response would be significantly worse since GIS is based on traditional (relational) backend. OLAP-GIS system offer great potential for powerful numerical-spatial decision support in community health analysis. The functionality of an OLAP-GIS system has been shown through a series of
Numerical Aspects of Eigenvalue and Eigenfunction Computations for Chaotic Quantum Systems
Bäcker, A.
Summary: We give an introduction to some of the numerical aspects in quantum chaos. The classical dynamics of two-dimensional area-preserving maps on the torus is illustrated using the standard map and a perturbed cat map. The quantization of area-preserving maps given by their generating function is discussed and for the computation of the eigenvalues a computer program in Python is presented. We illustrate the eigenvalue distribution for two types of perturbed cat maps, one leading to COE and the other to CUE statistics. For the eigenfunctions of quantum maps we study the distribution of the eigenvectors and compare them with the corresponding random matrix distributions. The Husimi representation allows for a direct comparison of the localization of the eigenstates in phase space with the corresponding classical structures. Examples for a perturbed cat map and the standard map with different parameters are shown. Billiard systems and the corresponding quantum billiards are another important class of systems (which are also relevant to applications, for example in mesoscopic physics). We provide a detailed exposition of the boundary integral method, which is one important method to determine the eigenvalues and eigenfunctions of the Helmholtz equation. We discuss several methods to determine the eigenvalues from the Fredholm equation and illustrate them for the stadium billiard. The occurrence of spurious solutions is discussed in detail and illustrated for the circular billiard, the stadium billiard, and the annular sector billiard. We emphasize the role of the normal derivative function to compute the normalization of eigenfunctions, momentum representations or autocorrelation functions in a very efficient and direct way. Some examples for these quantities are given and discussed.
Numerical Model of the Human Cardiovascular System-Korotkoff Sounds Simulation
Czech Academy of Sciences Publication Activity Database
Maršík, František; Převorovská, Světlana; Brož, Z.; Štembera, V.
Vol.4, č. 2 (2004), s. 193-199 ISSN 1432-9077 R&D Projects: GA ČR GA106/03/1073 Institutional research plan: CEZ:AV0Z2076919 Keywords : cardiovascular system * Korotkoff sounds * numerical simulation Subject RIV: BK - Fluid Dynamics
RELAP5 two-phase fluid model and numerical scheme for economic LWR system simulation
International Nuclear Information System (INIS)
Ransom, V.H.; Wagner, R.J.; Trapp, J.A.
1981-01-01
The RELAP5 two-phase fluid model and the associated numerical scheme are summarized. The experience accrued in development of a fast running light water reactor system transient analysis code is reviewed and example of the code application are given
Research on numerical control system based on S3C2410 and MCX314AL
Ren, Qiang; Jiang, Tingbiao
2008-10-01
With the rapid development of micro-computer technology, embedded system, CNC technology and integrated circuits, numerical control system with powerful functions can be realized by several high-speed CPU chips and RISC (Reduced Instruction Set Computing) chips which have small size and strong stability. In addition, the real-time operating system also makes the attainment of embedded system possible. Developing the NC system based on embedded technology can overcome some shortcomings of common PC-based CNC system, such as the waste of resources, low control precision, low frequency and low integration. This paper discusses a hardware platform of ENC (Embedded Numerical Control) system based on embedded processor chip ARM (Advanced RISC Machines)-S3C2410 and DSP (Digital Signal Processor)-MCX314AL and introduces the process of developing ENC system software. Finally write the MCX314AL's driver under the embedded Linux operating system. The embedded Linux operating system can deal with multitask well moreover satisfy the real-time and reliability of movement control. NC system has the advantages of best using resources and compact system with embedded technology. It provides a wealth of functions and superior performance with a lower cost. It can be sure that ENC is the direction of the future development.
Experimental and Numerical Analyses of New Massive Wooden Shear-Wall Systems
Directory of Open Access Journals (Sweden)
Luca Pozza
2014-07-01
Full Text Available Three innovative massive wooden shear-wall systems (Cross-Laminated-Glued Wall, Cross-Laminated-Stapled Wall, Layered Wall with dovetail inserts were tested and their structural behaviour under seismic action was assessed with numerical simulations. The wall specimens differ mainly in the method used to assemble the layers of timber boards composing them. Quasi-static cyclic loading tests were carried out and then reproduced with a non-linear numerical model calibrated on the test results to estimate the most appropriate behaviour factor for each system. Non-linear dynamic simulations of 15 artificially generated seismic shocks showed that these systems have good dissipative capacity when correctly designed and that they can be assigned to the medium ductility class of Eurocode 8. This work also shows the influence of deformations in wooden panels and base connectors on the behaviour factor and dissipative capacity of the system.
International Nuclear Information System (INIS)
Wen Zheng; Liu Yu; Yang Wenjiang; Qiu Ming
2007-01-01
In this paper, we present a study of the quasi-static and dynamic behaviour of high-T c superconductors (HTS hereafter) using a model suspension vibration testing system based on the magnetic launch assistance concept. The stiffness and damping of the levitation system under specified vibration circumstances was calculated by drawing on harmonic response analysis and half-power points method. Also, the equation of motion of the suspension system was presented in this paper, and with an attempt to analyse and predict mechanical characteristics of HTS in dynamic conditions. The obtained results of the suspending motion behaviour by numerical calculation are compared with experimental analytical results. Experimental technique combined with a numerical simulation method is a useful tool for measuring and analysing motion-dependent magnetic forces for the prediction and control of suspension systems
Zhu, Chen-Xi; Wang, Chi-Chuan
2018-01-01
This study proposes a numerical model for plate heat exchanger that is capable of handling supercritical CO2 fluid. The plate heat exchangers under investigation include Z-type (1-pass), U-type (1-pass), and 1-2 pass configurations. The plate spacing is 2.9 mm with a plate thickness of 0.8 mm, and the size of the plate is 600 mm wide and 218 mm in height with 60 degrees chevron angle. The proposed model takes into account the influence of gigantic change of CO2 properties. The simulation is first compared with some existing data for water-to-water plate heat exchangers with good agreements. The flow distribution, pressure drop, and heat transfer performance subject to the supercritical CO2 in plate heat exchangers are then investigated. It is found that the flow velocity increases consecutively from the entrance plate toward the last plate for the Z-type arrangement, and this is applicable for either water side or CO2 side. However, the flow distribution of the U-type arrangement in the water side shows opposite trend. Conversely, the flow distribution for U-type arrangement of CO2 depends on the specific flow ratio (C*). A lower C* like 0.1 may reverse the distribution, i.e. the flow velocity increases moderately alongside the plate channel like Z-type while a large C* of 1 would resemble the typical distribution in water channel. The flow distribution of CO2 side at the first and last plate shows a pronounced drop/surge phenomenon while the channels in water side does not reveal this kind of behavior. The performance of 2-pass plate heat exchanger, in terms of heat transfer rate, is better than that of 1-pass design only when C* is comparatively small (C* < 0.5). Multi-pass design is more effective when the dominant thermal resistance falls in the CO2 side.
A New Method to Solve Numeric Solution of Nonlinear Dynamic System
Directory of Open Access Journals (Sweden)
Min Hu
2016-01-01
Full Text Available It is well known that the cubic spline function has advantages of simple forms, good convergence, approximation, and second-order smoothness. A particular class of cubic spline function is constructed and an effective method to solve the numerical solution of nonlinear dynamic system is proposed based on the cubic spline function. Compared with existing methods, this method not only has high approximation precision, but also avoids the Runge phenomenon. The error analysis of several methods is given via two numeric examples, which turned out that the proposed method is a much more feasible tool applied to the engineering practice.
Increased-accuracy numerical modeling of electron-optical systems with space-charge
International Nuclear Information System (INIS)
Sveshnikov, V.
2011-01-01
This paper presents a method for improving the accuracy of space-charge computation for electron-optical systems. The method proposes to divide the computational region into two parts: a near-cathode region in which analytical solutions are used and a basic one in which numerical methods compute the field distribution and trace electron ray paths. A numerical method is used for calculating the potential along the interface, which involves solving a non-linear equation. Preliminary results illustrating the improvement of accuracy and the convergence of the method for a simple test example are presented.
Numerical Simulation of the Oscillations in a Mixer: An Internal Aeroacoustic Feedback System
Jorgenson, Philip C. E.; Loh, Ching Y.
2004-01-01
The space-time conservation element and solution element method is employed to numerically study the acoustic feedback system in a high temperature, high speed wind tunnel mixer. The computation captures the self-sustained feedback loop between reflecting Mach waves and the shear layer. This feedback loop results in violent instabilities that are suspected of causing damage to some tunnel components. The computed frequency is in good agreement with the available experimental data. The physical phenomena are explained based on the numerical results.
Real-time numerical simulation with high efficiency for an experimental reactor system
International Nuclear Information System (INIS)
Ding Shuling; Li Fu; Li Sifeng; Chu Xinyuan
2006-01-01
The paper presents a systematic and efficient method for numerical real-time simulation of an experimental reactor. The reactor models were built based on the physical characteristics of the experimental reactor, and several real-time simulation approaches were discussed and compared in the paper. How to implement the real-time reactor simulation system in Windows platform for the sake of hardware-in-loop experiment for the reactor power control system was discussed. (authors)
Numerical simulation of groundwater flow for the Yakima River basin aquifer system, Washington
Ely, D.M.; Bachmann, M.P.; Vaccaro, J.J.
2011-01-01
A regional, three-dimensional, transient numerical model of groundwater flow was constructed for the Yakima River basin aquifer system to better understand the groundwater-flow system and its relation to surface-water resources. The model described in this report can be used as a tool by water-management agencies and other stakeholders to quantitatively evaluate proposed alternative management strategies that consider the interrelation between groundwater availability and surface-water resources.
Numerical modelling of multi-vane expander operating conditions in ORC system
Rak, Józef; Błasiak, Przemysław; Kolasiński, Piotr
2017-11-01
Multi-vane expanders are positive displacement volumetric machines which are nowadays considered for application in micro-power domestic ORC systems as promising alternative to micro turbines and other volumetric expanders. The multi-vane expander features very simple design, low gas flow capacity, low expansion ratios, an advantageous ratio of the power output to the external dimensions and are insensitive to the negative influence of the gas-liquid mixture expansion. Moreover, the multi-vane expander can be easily hermetically sealed, which is one of the key issues in the ORC system design. A literature review indicates that issues concerning the application of multi-vane expanders in such systems, especially related to operating of multi-vane expander with different low-boiling working fluids, are innovative, not fully scientifically described and have the potential for practical implementation. In this paper the results of numerical investigations on multi-vane expander operating conditions are presented. The analyses were performed on three-dimensional numerical model of the expander in ANSYS CFX software. The numerical model of the expander was validated using the data obtained from the experiment carried out on a lab test-stand. Then a series of computational analysis were performed using expanders' numerical model in order to determine its operating conditions under various flow conditions of different working fluids.
Numerical modeling of an enhanced very early time electromagnetic (VETEM) prototype system
Cui, T.J.; Chew, W.C.; Aydiner, A.A.; Wright, D.L.; Smith, D.V.; Abraham, J.D.
2000-01-01
In this paper, two numerical models are presented to simulate an enhanced very early time electromagnetic (VETEM) prototype system, which is used for buried-object detection and environmental problems. Usually, the VETEM system contains a transmitting loop antenna and a receiving loop antenna, which run on a lossy ground to detect buried objects. In the first numerical model, the loop antennas are accurately analyzed using the Method of Moments (MoM) for wire antennas above or buried in lossy ground. Then, Conjugate Gradient (CG) methods, with the use of the fast Fourier transform (FFT) or MoM, are applied to investigate the scattering from buried objects. Reflected and scattered magnetic fields are evaluated at the receiving loop to calculate the output electric current. However, the working frequency for the VETEM system is usually low and, hence, two magnetic dipoles are used to replace the transmitter and receiver in the second numerical model. Comparing these two models, the second one is simple, but only valid for low frequency or small loops, while the first modeling is more general. In this paper, all computations are performed in the frequency domain, and the FFT is used to obtain the time-domain responses. Numerical examples show that simulation results from these two models fit very well when the frequency ranges from 10 kHz to 10 MHz, and both results are close to the measured data.
Numerical modelling of multi-vane expander operating conditions in ORC system
Directory of Open Access Journals (Sweden)
Rak Józef
2017-01-01
Full Text Available Multi-vane expanders are positive displacement volumetric machines which are nowadays considered for application in micro-power domestic ORC systems as promising alternative to micro turbines and other volumetric expanders. The multi-vane expander features very simple design, low gas flow capacity, low expansion ratios, an advantageous ratio of the power output to the external dimensions and are insensitive to the negative influence of the gas-liquid mixture expansion. Moreover, the multi-vane expander can be easily hermetically sealed, which is one of the key issues in the ORC system design. A literature review indicates that issues concerning the application of multi-vane expanders in such systems, especially related to operating of multi-vane expander with different low-boiling working fluids, are innovative, not fully scientifically described and have the potential for practical implementation. In this paper the results of numerical investigations on multi-vane expander operating conditions are presented. The analyses were performed on three-dimensional numerical model of the expander in ANSYS CFX software. The numerical model of the expander was validated using the data obtained from the experiment carried out on a lab test-stand. Then a series of computational analysis were performed using expanders' numerical model in order to determine its operating conditions under various flow conditions of different working fluids.
Energy Technology Data Exchange (ETDEWEB)
Cuntz, M., E-mail: cuntz@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019-0059 (United States)
2015-01-10
In the first paper of this series, a comprehensive approach has been provided for the study of S-type and P-type habitable regions in stellar binary systems, which was, however, restricted to circular orbits of the stellar components. Fortunately, a modest modification of the method also allows for the consideration of elliptical orbits, which of course entails a much broader range of applicability. This augmented method is presented here, and numerous applications are conveyed. In alignment with Paper I, the selected approach considers a variety of aspects, which comprise the consideration of a joint constraint including orbital stability and a habitable region for a possible system planet through the stellar radiative energy fluxes ({sup r}adiative habitable zone{sup ;} RHZ). The devised method is based on a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are deduced for which kinds of systems S-type and P-type habitable zones are realized. If the RHZs are truncated by the additional constraint of orbital stability, the notation of ST-type and PT-type habitability applies. In comparison to the circular case, it is found that in systems of higher eccentricity, the range of the RHZs is significantly reduced. Moreover, for a considerable number of models, the orbital stability constraint also reduces the range of S-type and P-type habitability. Nonetheless, S-, P-, ST-, and PT-type habitability is identified for a considerable set of system parameters. The method as presented is utilized for BinHab, an online code available at The University of Texas at Arlington.
International Nuclear Information System (INIS)
Cuntz, M.
2015-01-01
In the first paper of this series, a comprehensive approach has been provided for the study of S-type and P-type habitable regions in stellar binary systems, which was, however, restricted to circular orbits of the stellar components. Fortunately, a modest modification of the method also allows for the consideration of elliptical orbits, which of course entails a much broader range of applicability. This augmented method is presented here, and numerous applications are conveyed. In alignment with Paper I, the selected approach considers a variety of aspects, which comprise the consideration of a joint constraint including orbital stability and a habitable region for a possible system planet through the stellar radiative energy fluxes ( r adiative habitable zone ; RHZ). The devised method is based on a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are deduced for which kinds of systems S-type and P-type habitable zones are realized. If the RHZs are truncated by the additional constraint of orbital stability, the notation of ST-type and PT-type habitability applies. In comparison to the circular case, it is found that in systems of higher eccentricity, the range of the RHZs is significantly reduced. Moreover, for a considerable number of models, the orbital stability constraint also reduces the range of S-type and P-type habitability. Nonetheless, S-, P-, ST-, and PT-type habitability is identified for a considerable set of system parameters. The method as presented is utilized for BinHab, an online code available at The University of Texas at Arlington
Conjugate gradient type methods for linear systems with complex symmetric coefficient matrices
Freund, Roland
1989-01-01
We consider conjugate gradient type methods for the solution of large sparse linear system Ax equals b with complex symmetric coefficient matrices A equals A(T). Such linear systems arise in important applications, such as the numerical solution of the complex Helmholtz equation. Furthermore, most complex non-Hermitian linear systems which occur in practice are actually complex symmetric. We investigate conjugate gradient type iterations which are based on a variant of the nonsymmetric Lanczos algorithm for complex symmetric matrices. We propose a new approach with iterates defined by a quasi-minimal residual property. The resulting algorithm presents several advantages over the standard biconjugate gradient method. We also include some remarks on the obvious approach to general complex linear systems by solving equivalent real linear systems for the real and imaginary parts of x. Finally, numerical experiments for linear systems arising from the complex Helmholtz equation are reported.
International Nuclear Information System (INIS)
Bolstad, J.W.; Foster, R.D.; Gregory, W.S.
1983-01-01
A package of physical models simulating the heat transfer processes occurring between combustion gases and ducts in ventilation systems is described. The purpose of the numerical model is to predict how the combustion gas in a system heats up or cools down as it flows through the ducts in a ventilation system under fire conditions. The model treats a duct with (forced convection) combustion gases flowing on the inside and stagnant ambient air on the outside. The model is composed of five submodels of heat transfer processes along with a numerical solution procedure to evaluate them. Each of these quantities is evaluated independently using standard correlations based on experimental data. The details of the physical assumptions, simplifications, and ranges of applicability of the correlations are described. A typical application of this model to a full-scale fire test is discussed, and model predictions are compared with selected experimental data
Development of high velocity gas gun with a new trigger system-numerical analysis
Husin, Z.; Homma, H.
2018-02-01
In development of high performance armor vests, we need to carry out well controlled experiments using bullet speed of more than 900 m/sec. After reviewing trigger systems used for high velocity gas guns, this research intends to develop a new trigger system, which can realize precise and reproducible impact tests at impact velocity of more than 900 m/sec. A new trigger system developed here is called a projectile trap. A projectile trap is placed between a reservoir and a barrel. A projectile trap has two functions of a sealing disk and triggering. Polyamidimide is selected for the trap material and dimensions of the projectile trap are determined by numerical analysis for several levels of launching pressure to change the projectile velocity. Numerical analysis results show that projectile trap designed here can operate reasonably and stresses caused during launching operation are less than material strength. It means a projectile trap can be reused for the next shooting.
International Nuclear Information System (INIS)
Tong, S.S.; Powell, D.; Goel, S.
1992-02-01
A new software system called Engineous combines artificial intelligence and numerical methods for the design and optimization of complex aerospace systems. Engineous combines the advanced computational techniques of genetic algorithms, expert systems, and object-oriented programming with the conventional methods of numerical optimization and simulated annealing to create a design optimization environment that can be applied to computational models in various disciplines. Engineous has produced designs with higher predicted performance gains that current manual design processes - on average a 10-to-1 reduction of turnaround time - and has yielded new insights into product design. It has been applied to the aerodynamic preliminary design of an aircraft engine turbine, concurrent aerodynamic and mechanical preliminary design of an aircraft engine turbine blade and disk, a space superconductor generator, a satellite power converter, and a nuclear-powered satellite reactor and shield. 23 refs
International Nuclear Information System (INIS)
Mittal, R.C.; Rohila, Rajni
2016-01-01
In this paper, we have applied modified cubic B-spline based differential quadrature method to get numerical solutions of one dimensional reaction-diffusion systems such as linear reaction-diffusion system, Brusselator system, Isothermal system and Gray-Scott system. The models represented by these systems have important applications in different areas of science and engineering. The most striking and interesting part of the work is the solution patterns obtained for Gray Scott model, reminiscent of which are often seen in nature. We have used cubic B-spline functions for space discretization to get a system of ordinary differential equations. This system of ODE’s is solved by highly stable SSP-RK43 method to get solution at the knots. The computed results are very accurate and shown to be better than those available in the literature. Method is easy and simple to apply and gives solutions with less computational efforts.
Numerical Study on Density Gradient Carbon-Carbon Composite for Vertical Launching System
Yoon, Jin-Young; Kim, Chun-Gon; Lim, Juhwan
2018-04-01
This study presents new carbon-carbon (C/C) composite that has a density gradient within single material, and estimates its heat conduction performance by a numerical method. To address the high heat conduction of a high-density C/C, which can cause adhesion separation in the steel structures of vertical launching systems, density gradient carbon-carbon (DGCC) composite is proposed due to its exhibiting low thermal conductivity as well as excellent ablative resistance. DGCC is manufactured by hybridizing two different carbonization processes into a single carbon preform. One part exhibits a low density using phenolic resin carbonization to reduce heat conduction, and the other exhibits a high density using thermal gradient-chemical vapor infiltration for excellent ablative resistance. Numerical analysis for DGCC is performed with a heat conduction problem, and internal temperature distributions are estimated by the forward finite difference method. Material properties of the transition density layer, which is inevitably formed during DGCC manufacturing, are assumed to a combination of two density layers for numerical analysis. By comparing numerical results with experimental data, we validate that DGCC exhibits a low thermal conductivity, and it can serve as highly effective ablative material for vertical launching systems.
Experimental and numerical study of the MYRRHA control rod system dynamics
International Nuclear Information System (INIS)
Kennedy, G.; Lamberts, D.; Van Tichelen, K.; Profir, M.; Moreau, V.
2017-01-01
This paper presents an experimental and numerical investigation of the buoyancy driven MYRRHA control rod (CR) insertion during an emergency SCRAM. The study aimed to support the MYRRHA reactor design and characterise the hydrodynamic behaviour of the CR system while demonstrating the proof-of-principle. A full-scale mock-up test section of the MYRRHA CR was constructed to test the hydrodynamics in Lead Bismuth Eutectic over a wide range of operating conditions, to provide experimental data for the qualification of the CR system. A numerical CFD model of the CR test section was also setup in STAR-CCM+. The simulations make use of the recently developed overset mesh method to simulate the dynamic two-way coupling between the moving CR bundle and the fluid domain. The numerical methodology and post-test simulation results are validated against the experimental results. The steady state hydraulic results and the transient insertion results from both the experimental and numerical efforts are presented. The influence of the global process conditions on the CR insertion time are presented as well. This investigation successfully demonstrates the CR insertion proof-of-principle during a SCRAM. (author)
Majumdar, Alok K.; LeClair, Andre C.; Hedayat, Ali
2016-01-01
This paper presents a numerical model of pressurization of a cryogenic propellant tank for the Integrated Vehicle Fluid (IVF) system using the Generalized Fluid System Simulation Program (GFSSP). The IVF propulsion system, being developed by United Launch Alliance, uses boiloff propellants to drive thrusters for the reaction control system as well as to run internal combustion engines to develop power and drive compressors to pressurize propellant tanks. NASA Marshall Space Flight Center (MSFC) has been running tests to verify the functioning of the IVF system using a flight tank. GFSSP, a finite volume based flow network analysis software developed at MSFC, has been used to develop an integrated model of the tank and the pressurization system. This paper presents an iterative algorithm for converging the interface boundary conditions between different component models of a large system model. The model results have been compared with test data.
Directory of Open Access Journals (Sweden)
Tugen Feng
2017-12-01
Full Text Available The objective of this study is to investigate the 3D behavior characteristics of an excavation supported by an innovative prestressed support (IPS earth retention system. A numerical simulation was conducted in order to provide insight into the IPS system behavior by using the FLAC3D package. Prior to the parametric study, validation work was conducted by means of a comparison of the deformation between the field test data and numerical analysis results, and strong agreement was obtained. The reasonable excavation location, layered excavation thickness, and blocked excavation sequence are presented according to variable parameter analysis. In view of the previous findings, certain measurements are proposed in order to control the foundation pit deformation. The results indicate that prestress compensation has a significant effect on the IPS system behavior, while an optimized excavation sequence slightly improves its behavior. With the conclusion proposed based on the numerical results, the aim is to provide reference data for optimization design and the construction sequence. Keywords: FLAC3D, IPS system, Prestress compensation, Layered excavation, Blocked excavation, Deformation control
International Nuclear Information System (INIS)
Wang Chi; Zhou Yu-Qiu; Shen Gao-Wei; Wu Wen-Wen; Ding Wei
2013-01-01
The method of numerical analysis is employed to study the resonance mechanism of the lumped parameter system model for acoustic mine detection. Based on the basic principle of the acoustic resonance technique for mine detection and the characteristics of low-frequency acoustics, the ''soil-mine'' system could be equivalent to a damping ''mass-spring'' resonance model with a lumped parameter analysis method. The dynamic simulation software, Adams, is adopted to analyze the lumped parameter system model numerically. The simulated resonance frequency and anti-resonance frequency are 151 Hz and 512 Hz respectively, basically in agreement with the published resonance frequency of 155 Hz and anti-resonance frequency of 513 Hz, which were measured in the experiment. Therefore, the technique of numerical simulation is validated to have the potential for analyzing the acoustic mine detection model quantitatively. The influences of the soil and mine parameters on the resonance characteristics of the soil—mine system could be investigated by changing the parameter setup in a flexible manner. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Żymełka, Piotr; Nabagło, Daniel; Janda, Tomasz; Madejski, Paweł
2017-12-01
Balanced distribution of air in coal-fired boiler is one of the most important factors in the combustion process and is strongly connected to the overall system efficiency. Reliable and continuous information about combustion airflow and fuel rate is essential for achieving optimal stoichiometric ratio as well as efficient and safe operation of a boiler. Imbalances in air distribution result in reduced boiler efficiency, increased gas pollutant emission and operating problems, such as corrosion, slagging or fouling. Monitoring of air flow trends in boiler is an effective method for further analysis and can help to appoint important dependences and start optimization actions. Accurate real-time monitoring of the air distribution in boiler can bring economical, environmental and operational benefits. The paper presents a novel concept for online monitoring system of air distribution in coal-fired boiler based on real-time numerical calculations. The proposed mathematical model allows for identification of mass flow rates of secondary air to individual burners and to overfire air (OFA) nozzles. Numerical models of air and flue gas system were developed using software for power plant simulation. The correctness of the developed model was verified and validated with the reference measurement values. The presented numerical model for real-time monitoring of air distribution is capable of giving continuous determination of the complete air flows based on available digital communication system (DCS) data.
Directory of Open Access Journals (Sweden)
Żymełka Piotr
2017-12-01
Full Text Available Balanced distribution of air in coal-fired boiler is one of the most important factors in the combustion process and is strongly connected to the overall system efficiency. Reliable and continuous information about combustion airflow and fuel rate is essential for achieving optimal stoichiometric ratio as well as efficient and safe operation of a boiler. Imbalances in air distribution result in reduced boiler efficiency, increased gas pollutant emission and operating problems, such as corrosion, slagging or fouling. Monitoring of air flow trends in boiler is an effective method for further analysis and can help to appoint important dependences and start optimization actions. Accurate real-time monitoring of the air distribution in boiler can bring economical, environmental and operational benefits. The paper presents a novel concept for online monitoring system of air distribution in coal-fired boiler based on real-time numerical calculations. The proposed mathematical model allows for identification of mass flow rates of secondary air to individual burners and to overfire air (OFA nozzles. Numerical models of air and flue gas system were developed using software for power plant simulation. The correctness of the developed model was verified and validated with the reference measurement values. The presented numerical model for real-time monitoring of air distribution is capable of giving continuous determination of the complete air flows based on available digital communication system (DCS data.
Energy Technology Data Exchange (ETDEWEB)
Koss, K. G.; Petrov, O. F.; Myasnikov, M. I., E-mail: miasnikovmi@mail.ru; Statsenko, K. B.; Vasiliev, M. M. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)
2016-07-15
The results of experimental and numerical analysis are presented for phase transitions in strongly nonequilibrium small systems of strongly interacting Brownian particles. The dynamic entropy method is applied to analysis of the state of these systems. Experiments are carried out with kinetic heating of the structures of micron-size particles in a laboratory rf discharge plasma. Three phase states of these small systems are observed: crystalline, liquid, and transient. The mechanism of phase transitions in cluster structures of strongly interacting particles is described.
Rosenbaum, J. S.
1971-01-01
Systems of ordinary differential equations in which the magnitudes of the eigenvalues (or time constants) vary greatly are commonly called stiff. Such systems of equations arise in nuclear reactor kinetics, the flow of chemically reacting gas, dynamics, control theory, circuit analysis and other fields. The research reported develops an A-stable numerical integration technique for solving stiff systems of ordinary differential equations. The method, which is called the generalized trapezoidal rule, is a modification of the trapezoidal rule. However, the method is computationally more efficient than the trapezoidal rule when the solution of the almost-discontinuous segments is being calculated.
Pervin, Mollika; Ghergut, Iulia; Graf, Thomas; Peche, Aaron
2016-04-01
Most geothermal reservoirs are of the liquid-dominated type, and their unexploited-state pressure profile approximately follows the hydrostatic gradient. In very hot liquid-dominated systems, temperature typically follows a boiling-point-for-depth (BPD) relationship. By contrast, vapor-dominated systems exhibit (in their unexploited state) surprisingly small vertical gradients of temperature and pressure, such that a constantly high temperature is encountered over a large vertical thickness, while their pressure approximately follows vapour pressure, pvap(T°). This implies that (Pruess 1985, Truesdell and White 1973): (i) for a vapor-dominated reservoir to exist, it must be sealed laterally - otherwise it would be flooded by neighboring groundwaters with hydrostatic p profile, and (ii) liquid water should somehow be present in the whole system - otherwise p values would not be constrained by the pvap(T°) relationship for water. Historically, one of the most puzzling aspects of vapor-dominated systems was the large amount of heat flowing upwards, while vertical T° gradients remained negligible. This mechanism was deemed as 'heat pipe'(HP) (Eastman 1968): In the central zone of a vapor-dominated system, both vapor and liquid are mobile; vapor flows upwards, condenses at shallower depth, and the liquid condensate flows downwards. Due to the large amount of latent enthalpy released in vapor condensation, the vapor-liquid counter-flow can generate large rates of heat flow with negligible net mass transport (Pruess 1985). In order to be able to exploit two-phase (including vapor-dominated) reservoirs in a sustainable manner, one first needs to understand the conditions under which a two-phase (or a vapor-dominated) system has evolved naturally, and which have led to its present (quasi-) steady undisturbed state. Past studies have found that HP can exist in two distinct states, corresponding to liquid-dominated and vapor-dominated p profiles, respectively. Within this
Modeling and numerical simulation of interior ballistic processes in a 120mm mortar system
Acharya, Ragini
Numerical Simulation of interior ballistic processes in gun and mortar systems is a very difficult and interesting problem. The mathematical model for the physical processes in the mortar systems consists of a system of non-linear coupled partial differential equations, which also contain non-homogeneity in form of the source terms. This work includes the development of a three-dimensional mortar interior ballistic (3D-MIB) code for a 120mm mortar system and its stage-wise validation with multiple sets of experimental data. The 120mm mortar system consists of a flash tube contained within an ignition cartridge, tail-boom, fin region, charge increments containing granular propellants, and a projectile payload. The ignition cartridge discharges hot gas-phase products and unburned granular propellants into the mortar tube through vent-holes on its surface. In view of the complexity of interior ballistic processes in the mortar propulsion system, the overall problem was solved in a modular fashion, i.e., simulating each physical component of the mortar propulsion system separately. These modules were coupled together with appropriate initial and boundary conditions. The ignition cartridge and mortar tube contain nitrocellulose-based ball propellants. Therefore, the gas dynamical processes in the 120mm mortar system are two-phase, which were simulated by considering both phases as an interpenetrating continuum. Mass and energy fluxes from the flash tube into the granular bed of ignition cartridge were determined from a semi-empirical technique. For the tail-boom section, a transient one-dimensional two-phase compressible flow solver based on method of characteristics was developed. The mathematical model for the interior ballistic processes in the mortar tube posed an initial value problem with discontinuous initial conditions with the characteristics of the Riemann problem due to the discontinuity of the initial conditions. Therefore, the mortar tube model was solved
Directory of Open Access Journals (Sweden)
Jianlin Luo
2017-03-01
Full Text Available The health conditions of complicated concrete structures require intrinsic cement-based sensors with a fast sensing response and high accuracy. In this paper, static, modal, harmonic, and transient dynamic analyses for the 0–3 type piezoelectric cement-based material with interdigitated electrodes (IEPCM wafer were investigated using the ANSYS finite element numerical approach. Optimal design of the IEPCM was further implemented with electrode distance (P, electrode width (W, and wafer density (H as the main parameters. Analysis results show that the maximum stress and strain in the x-polarization direction of the IEPCM are 2.6 and 3.19 times higher than that in the y-direction, respectively; there exists no repetition frequency phenomenon for the IEPCM. These indicate 0–3 type IEPCM possesses good orthotropic features, and lateral driving capacity notwithstanding, a hysteresis effect exists. Allowing for the wafer width (Wp of 1 mm, the optimal design of the IEPCM wafer arrives at the best physical values of H, W and P are 6.2, 0.73 and 1.02 mm respectively, whereas the corresponding optimal volume is 10.9 mm3.
Understanding information retrieval systems management, types, and standards
Bates, Marcia J
2011-01-01
In order to be effective for their users, information retrieval (IR) systems should be adapted to the specific needs of particular environments. The huge and growing array of types of information retrieval systems in use today is on display in Understanding Information Retrieval Systems: Management, Types, and Standards, which addresses over 20 types of IR systems. These various system types, in turn, present both technical and management challenges, which are also addressed in this volume. In order to be interoperable in a networked environment, IR systems must be able to use various types of
Barrabés, E.; Mondelo, J. M.; Ollé, M.
2013-10-01
This paper is devoted to the numerical computation and continuation of families of heteroclinic connections between hyperbolic periodic orbits (POs) of a Hamiltonian system. We describe a method that requires the numerical continuation of a nonlinear system that involves the initial conditions of the two POs, the linear approximations of the corresponding manifolds and a point in a given Poincaré section where the unstable and stable manifolds match. The method is applied to compute families of heteroclinic orbits between planar Lyapunov POs around the collinear equilibrium points of the restricted three-body problem in different scenarios. In one of them, for the Sun-Jupiter mass parameter, we provide energy ranges for which the transition between different resonances is possible.
46 CFR 153.310 - Ventilation system type.
2010-10-01
... 46 Shipping 5 2010-10-01 2010-10-01 false Ventilation system type. 153.310 Section 153.310... Handling Space Ventilation § 153.310 Ventilation system type. A cargo handling space must have a permanent forced ventilation system of the exhaust type. ...
Convergence of a numerical method for the compressible Navier-Stokes system on general domains
Czech Academy of Sciences Publication Activity Database
Feireisl, Eduard; Karper, T.; Michálek, Martin
2016-01-01
Roč. 134, č. 4 (2016), s. 667-704 ISSN 0029-599X R&D Projects: GA ČR GA13-00522S Institutional support: RVO:67985840 Keywords : numerical methods * Navier - Stokes system Subject RIV: BA - General Mathematics Impact factor: 2.152, year: 2016 http://link.springer.com/article/10.1007%2Fs00211-015-0786-6
Convergence of a numerical method for the compressible Navier-Stokes system on general domains
Czech Academy of Sciences Publication Activity Database
Feireisl, Eduard; Karper, T.; Michálek, Martin
2016-01-01
Roč. 134, č. 4 (2016), s. 667-704 ISSN 0029-599X R&D Projects: GA ČR GA13-00522S Institutional support: RVO:67985840 Keywords : numerical methods * Navier-Stokes system Subject RIV: BA - General Mathematics Impact factor: 2.152, year: 2016 http://link.springer.com/article/10.1007%2Fs00211-015-0786-6
CHEMSIMUL - A program package for numerical simulation of chemical reaction systems
International Nuclear Information System (INIS)
Lang Rasmussen, O.; Bjergbakke, E.
1984-01-01
A description is given of a program package, CHEMSIMUL, for numerical simulation of chemical reaction systems. The main components in the package are a translator of chemical equations to differential equations, a balance equation program, a differential equation solver, EPISODE, and an input/output program. The performance of the program is demonstrated by four examples. A manual for the input file and the complete program text with comments are given in Appendices I and II. (author)
Numerical and experimental flow analysis in centifluidic systems for rapid allergy screening tests
Directory of Open Access Journals (Sweden)
Dethloff Manuel
2015-09-01
Full Text Available For the development of the automated processing of a membrane-based rapid allergy test, the flow characteristics in one part of the test, the reagents module, are analysed. This module consists of a multichannel system with several inputs and one output. A return flow from one input channel into another should be avoided. A valveless module with pointed channels at an angle of 12° is analysed with numerical and experimental methods with regard to the flow characteristics.
The Navier-Stokes-Fourier system: From weak solutions to numerical analysis
Czech Academy of Sciences Publication Activity Database
Feireisl, Eduard
2015-01-01
Roč. 35, č. 3 (2015), s. 185-193 ISSN 0174-4747 R&D Projects: GA ČR GA13-00522S Institutional support: RVO:67985840 Keywords : Navier-Stokes-Fourier system * weak solution * mixed finite-volume finite-element numerical scheme Subject RIV: BA - General Mathematics http://www.degruyter.com/view/j/anly.2015.35.issue-3/anly-2014-1300/anly-2014-1300. xml
Czech Academy of Sciences Publication Activity Database
Feireisl, Eduard; Hošek, Radim; Maltese, D.; Novotný, A.
2017-01-01
Roč. 33, č. 4 (2017), s. 1208-1223 ISSN 0749-159X EU Projects: European Commission(XE) 320078 - MATH EF Institutional support: RVO:67985840 Keywords : convergence * error estimates * mixed numerical method * Navier–Stokes system Subject RIV: BA - General Math ematics OBOR OECD: Pure math ematics Impact factor: 1.079, year: 2016 http://onlinelibrary.wiley.com/doi/10.1002/num.22140/abstract
A numerical scheme for the one-dimensional pressureless gases system
Boudin , Laurent; Mathiaud , Julien
2012-01-01
International audience; In this work, we investigate the numerical solving of the one-dimensional pressureless gases system. After briefly recalling the mathematical framework of the duality solutions introduced by Bouchut and James, we point out that the upwind scheme for the density and momentum does not satisfy the one-sided Lipschitz (OSL) condition on the expansion rate required for the duality solutions. Then we build a diffusive scheme which allows to recover the OSL condition by follo...
International Nuclear Information System (INIS)
Meltz, Bertrand
2015-01-01
This thesis deals with the mathematical and numerical analysis of the systems of compressible hydrodynamics and radiative transfer. More precisely, we study the derivation of numerical methods with 2D polar coordinates (one for the radius, one for the angle) where equations are discretized on regular polar grids. On one hand, these methods are well-suited for the simulation of flows with polar symmetries since they preserve these symmetries by construction. On the other hand, such coordinates systems introduce geometrical singularities as well as geometrical source terms which must be carefully treated. The first part of this document is devoted to the study of hydrodynamics equations, or Euler equations. We propose a new class of arbitrary high-order numerical schemes in both space and time and rely on directional splitting methods for the resolution of 2D equations. Each sub-system is solved using a Lagrange+Remap solver. We study the influence of the r=0 geometrical singularities of the cylindrical and spherical coordinates systems on the precision of the 2D numerical solutions. The second part of this document is devoted to the study of radiative transfer equations. In these equations, the unknowns depend on a large number of variables and a stiff source term is involved. The main difficulty consists in capturing the correct asymptotic behavior on coarse grids. We first construct a class of models where the radiative intensity is projected on a truncated spherical harmonics basis in order to lower the number of mathematical dimensions. Then we propose an Asymptotic Preserving scheme built in polar coordinates and we show that the scheme capture the correct diffusion limit in the radial direction as well as in the polar direction. (author) [fr
Numerical study on cavitation inception in the rotary valve of the hydraulic power steering system
International Nuclear Information System (INIS)
Ryu, Gwang Nyeon; Cho, Myung Hwan; Yoo, Jung Yul; Park, Sun Hong
2009-01-01
The rotary valve directs the power steering oil to either side of a power piston and relieves the driver of the effort to turn the wheel, when a driver begins to operate the vehicle. It is well known that the hiss noise occurring at that moment is caused mainly by cavitation of the oil inside the rotary valve. In this paper, two types of rotary valve (round and straight type) have been analyzed numerically using three-dimensional cavitation model embedded in the commercial code, FLUENT v6.2 and the results have been compared with the measured hiss noise level in a semi-anechoic chamber. The volume of the oil vapor generated from cavitation was larger in Round type valve which has a convex shape of the sleeve grooves than in Straight type valve which has a rectangular shape of the sleeve grooves. The hiss noise level of Round type valve was higher than that of Straight type valve as well. These results mean that the hiss noise can be reduced by the change of the shape of the grooves.
Numerical Solution of Nonlinear Volterra Integral Equations System Using Simpson’s 3/8 Rule
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Adem Kılıçman
2012-01-01
Full Text Available The Simpson’s 3/8 rule is used to solve the nonlinear Volterra integral equations system. Using this rule the system is converted to a nonlinear block system and then by solving this nonlinear system we find approximate solution of nonlinear Volterra integral equations system. One of the advantages of the proposed method is its simplicity in application. Further, we investigate the convergence of the proposed method and it is shown that its convergence is of order O(h4. Numerical examples are given to show abilities of the proposed method for solving linear as well as nonlinear systems. Our results show that the proposed method is simple and effective.
Bright, William
In most languages encountered by linguists, the numerals, considered as a paradigmatic set, constitute a morpho-syntactic problem of only moderate complexity. The Indo-Aryan language family of North India, however, presents a curious contrast. The relatively regular numeral system of Sanskrit, as it has developed historically into the modern…
International Nuclear Information System (INIS)
Meng, Erlin; Yu, Hang; Zhan, Guangyi; He, Yang
2013-01-01
Highlights: • A new type of PCM room is proposed, two kinds of PCM were used in the room. • The new room can decrease the indoor air temperature fluctuation by 4.3 °C in summer. • Indoor air temperature fluctuation was decreased by 14.2 °C in winter for the new room. • Important factors that affect the thermal performance of the new room were studied. - Abstract: A new type of phase change material (PCM) room was proposed in this paper to control the indoor air temperature for a better thermal comfort for human beings. That is to place two different kinds of PCM into room envelopes of different orientations. Both experimental and numerical studies were carried out for rooms with/without PCM. Indoor air temperature and interior surface heat flux of the two rooms were studied in typical summer and winter climate of Shanghai (31.2N, 121.5E). Important factors that affect the thermal performance of the PCM were studied, such as phase change temperature, thickness of the PCM and the arrangement of the two kinds of PCM in the room. Results showed that this new type of PCM room can decrease the indoor air temperature fluctuation by 4.3 °C in summer and 14.2 °C in winter. Different arrangements of the two kinds of PCM in the room can cause an indoor air temperature difference to be 6.9 °C in summer and 2.7 °C in winter
Snorradóttir, Bergthóra S; Jónsdóttir, Fjóla; Sigurdsson, Sven Th; Másson, Már
2014-08-01
A model is presented for transdermal drug delivery from single-layered silicone matrix systems. The work is based on our previous results that, in particular, extend the well-known Higuchi model. Recently, we have introduced a numerical transient model describing matrix systems where the drug dissolution can be non-instantaneous. Furthermore, our model can describe complex interactions within a multi-layered matrix and the matrix to skin boundary. The power of the modelling approach presented here is further illustrated by allowing the possibility of a donor solution. The model is validated by a comparison with experimental data, as well as validating the parameter values against each other, using various configurations with donor solution, silicone matrix and skin. Our results show that the model is a good approximation to real multi-layered delivery systems. The model offers the ability of comparing drug release for ibuprofen and diclofenac, which cannot be analysed by the Higuchi model because the dissolution in the latter case turns out to be limited. The experiments and numerical model outlined in this study could also be adjusted to more general formulations, which enhances the utility of the numerical model as a design tool for the development of drug-loaded matrices for trans-membrane and transdermal delivery. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.
Numerical Modeling of Cavitating Venturi: A Flow Control Element of Propulsion System
Majumdar, Alok; Saxon, Jeff (Technical Monitor)
2002-01-01
In a propulsion system, the propellant flow and mixture ratio could be controlled either by variable area flow control valves or by passive flow control elements such as cavitating venturies. Cavitating venturies maintain constant propellant flowrate for fixed inlet conditions (pressure and temperature) and wide range of outlet pressures, thereby maintain constant, engine thrust and mixture ratio. The flowrate through the venturi reaches a constant value and becomes independent of outlet pressure when the pressure at throat becomes equal to vapor pressure. In order to develop a numerical model of propulsion system, it is necessary to model cavitating venturies in propellant feed systems. This paper presents a finite volume model of flow network of a cavitating venturi. The venturi was discretized into a number of control volumes and mass, momentum and energy conservation equations in each control volume are simultaneously solved to calculate one-dimensional pressure, density, and flowrate and temperature distribution. The numerical model predicts cavitations at the throat when outlet pressure was gradually reduced. Once cavitation starts, with further reduction of downstream pressure, no change in flowrate is found. The numerical predictions have been compared with test data and empirical equation based on Bernoulli's equation.
Numerical design of electron guns and space charge limited transport systems
International Nuclear Information System (INIS)
Herrmannsfeldt, W.B.
1980-10-01
This paper describes the capabilities and limitations of computer programs used to design electron guns and similarly space-charge limited transport systems. Examples of computer generated plots from several different types of gun problems are included
Chierici, A.; Chirco, L.; Da Vià, R.; Manservisi, S.; Scardovelli, R.
2017-11-01
Nowadays the rapidly-increasing computational power allows scientists and engineers to perform numerical simulations of complex systems that can involve many scales and several different physical phenomena. In order to perform such simulations, two main strategies can be adopted: one may develop a new numerical code where all the physical phenomena of interest are modelled or one may couple existing validated codes. With the latter option, the creation of a huge and complex numerical code is avoided but efficient methods for data exchange are required since the performance of the simulation is highly influenced by its coupling techniques. In this work we propose a new algorithm that can be used for volume and/or boundary coupling purposes for both multiscale and multiphysics numerical simulations. The proposed algorithm is used for a multiscale simulation involving several CFD domains and monodimensional loops. We adopt the overlapping domain strategy, so the entire flow domain is simulated with the system code. We correct the system code solution by matching averaged inlet and outlet fields located at the boundaries of the CFD domains that overlap parts of the monodimensional loop. In particular we correct pressure losses and enthalpy values with source-sink terms that are imposed in the system code equations. The 1D-CFD coupling is a defective one since the CFD code requires point-wise values on the coupling interfaces and the system code provides only averaged quantities. In particular we impose, as inlet boundary conditions for the CFD domains, the mass flux and the mean enthalpy that are calculated by the system code. With this method the mass balance is preserved at every time step of the simulation. The coupling between consecutive CFD domains is not a defective one since with the proposed algorithm we can interpolate the field solutions on the boundary interfaces. We use the MED data structure as the base structure where all the field operations are
Majidi, Shahram; Leon Guerrero, Christopher R; Gandhy, Shreya; Burger, Kathleen M; Sigounas, Dimitri
2017-07-01
Central nervous system (CNS) involvement occurs in up to 50% of patients with systemic lupus erythematosus (SLE). Cerebral aneurysm formation is a rare complication of CNS lupus. The majority of these patients present with subarachnoid hemorrhage. We report a patient with an active SLE flare who presented with a recurrent ischemic stroke and was found to have numerous unruptured fusiform and saccular aneurysms in multiple vascular territories. He was treated with high-dose steroid and rituximab along with aspirin and blood pressure control for stroke prevention. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Bauge, E.; Bersillon, O.
2000-01-01
This paper presents the transparencies of the speech concerning the nuclear models, experiments and data libraries needed for numerical simulation of Accelerator-Driven Systems. The first part concerning the nuclear models defines the spallation process, the corresponding models (intra-nuclear cascade, statistical model, Fermi breakup, fission, transport, decay and macroscopic aspects) and the code systems. The second part devoted to the experiments presents the angular measurements, the integral measurements, the residual nuclei and the energy deposition. In the last part, dealing with the data libraries, the author details the fundamental quantities as the reaction cross-section, the low energy transport databases and the decay libraries. (A.L.B.)
Direct numerical control of machine tools in a nuclear research center by the CAMAC system
International Nuclear Information System (INIS)
Zwoll, K.; Mueller, K.D.; Becks, B.; Erven, W.; Sauer, M.
1977-01-01
The production of mechanical parts in research centers can be improved by connecting several numerically controlled machine tools to a central process computer via a data link. The CAMAC Serial Highway with its expandable structure yields an economic and flexible system for this purpose. The CAMAC System also facilitates the development of modular components controlling the machine tools itself. A CAMAC installation controlling three different machine tools connected to a central computer (PDP11) via the CAMAC Serial Highway is described. Besides this application, part of the CAMAC hardware and software can also be used for a great variety of scientific experiments
Numerical studies of entangled positive-partial-transpose states in composite quantum systems
International Nuclear Information System (INIS)
Leinaas, Jon Magne; Sollid, Per Oyvind; Myrheim, Jan
2010-01-01
We report here on the results of numerical searches for PPT states in a series of bipartite quantum systems of low dimensions. PPT states are represented by density matrices that remain positive semidefinite under partial transposition with respect to one of the subsystems, and our searches are for such states with specified ranks for the density matrix and its partial transpose. For a series of different ranks extremal PPT states and nonextremal entangled PPT states have been found. The results are listed in tables and charted in diagrams. Comparison of the results for systems of different dimensions reveals several regularities. We discuss lower and upper bounds on the ranks of extremal PPT states.
Hyperchaos Numerical Simulation and Control in a 4D Hyperchaotic System
Directory of Open Access Journals (Sweden)
Junhai Ma
2013-01-01
Full Text Available A hyperchaotic system is introduced, and the complex dynamical behaviors of such system are investigated by means of numerical simulations. The bifurcation diagrams, Lyapunov exponents, hyperchaotic attractors, the power spectrums, and time charts are mapped out through the theory analysis and dynamic simulations. The chaotic and hyper-chaotic attractors exist and alter over a wide range of parameters according to the variety of Lyapunov exponents and bifurcation diagrams. Furthermore, linear feedback controllers are designed for stabilizing the hyperchaos to the unstable equilibrium points; thus, we achieve the goal of a second control which is more useful in application.
International Nuclear Information System (INIS)
Tomiyama, Akio; Matsuoka, Toshiyuki.
1995-01-01
A simple numerical method for solving a transient incompressible two-fluid model was proposed in the present study. A general curvilinear coordinate system was adopted in this method for predicting transient flows in practical engineering devices. The simplicity of the present method is due to the fact that the field equations and constitutive equations were expressed in a tensor form in the general curvilinear coordinate system. When a conventional rectangular mesh is adopted in a calculation, the method reduces to a numerical method for a Cartesian coordinate system. As an example, the present method was applied to transient air-water bubbly flow in a vertical U-tube. It was confirmed that the effects of centrifugal and gravitational forces on the phase distribution in the U-tube were reasonably predicted. (author)
Experimental and Numerical Analysis of S-CO2 Critical Flow for SFR Recovery System Design
International Nuclear Information System (INIS)
Kim, Min Seok; Jung, Hwa-Young; Ahn, Yoonhan; Lee, Jekyoung; Lee, Jeong Ik
2016-01-01
This paper presents both numerical and experimental studies of the critical flow of S-CO 2 while special attention is given to the turbo-machinery seal design. A computational critical flow model is described first. The experiments were conducted to validate the critical flow model. Various conditions have been tested to study the flow characteristic and provide validation data for the model. The comparison of numerical and experimental results of S-CO 2 critical flow will be presented. In order to eliminate SWR, a concept of coupling the Supercritical CO 2 (S-CO 2 ) cycle with SFR has been proposed. It is known that for a closed system controlling the inventory is important for stable operation and achieving high efficiency. Since the S-CO 2 power cycle is a highly pressurized system, certain amount of leakage flow is inevitable in the rotating turbo-machinery via seals. To simulate the CO 2 leak flow in a turbo-machinery with higher accuracy in the future, the real gas effect and friction factor will be considered for the CO 2 critical flow model. Moreover, experimentally obtained temperature data were somewhat different from the numerically obtained temperature due to the insufficient insulation and large thermal inertia of the CO 2 critical flow facility. Insulation in connecting pipes and the low-pressure tank will be added and additional tests will be conducted
Numerical modeling of the agricultural-hydrologic system in Punjab, India
Nyblade, M.; Russo, T. A.; Zikatanov, L.; Zipp, K.
2017-12-01
The goal of food security for India's growing population is threatened by the decline in freshwater resources due to unsustainable water use for irrigation. The issue is acute in parts of Punjab, India, where small landholders produce a major quantity of India's food with declining groundwater resources. To further complicate this problem, other regions of the state are experiencing groundwater logging and salinization, and are reliant on canal systems for fresh water delivery. Due to the lack of water use records, groundwater consumption for this study is estimated with available data on crop yields, climate, and total canal water delivery. The hydrologic and agricultural systems are modeled using appropriate numerical methods and software. This is a state-wide hydrologic numerical model of Punjab that accounts for multiple aquifer layers, agricultural water demands, and interactions between the surface canal system and groundwater. To more accurately represent the drivers of agricultural production and therefore water use, we couple an economic crop optimization model with the hydrologic model. These tools will be used to assess and optimize crop choice scenarios based on farmer income, food production, and hydrologic system constraints. The results of these combined models can be used to further understand the hydrologic system response to government crop procurement policies and climate change, and to assess the effectiveness of possible water conservation solutions.
Numerical Solution of Piecewise Constant Delay Systems Based on a Hybrid Framework
Directory of Open Access Journals (Sweden)
H. R. Marzban
2016-01-01
Full Text Available An efficient numerical scheme for solving delay differential equations with a piecewise constant delay function is developed in this paper. The proposed approach is based on a hybrid of block-pulse functions and Taylor’s polynomials. The operational matrix of delay corresponding to the proposed hybrid functions is introduced. The sparsity of this matrix significantly reduces the computation time and memory requirement. The operational matrices of integration, delay, and product are employed to transform the problem under consideration into a system of algebraic equations. It is shown that the developed approach is also applicable to a special class of nonlinear piecewise constant delay differential equations. Several numerical experiments are examined to verify the validity and applicability of the presented technique.
Vilas, Carlos; Balsa-Canto, Eva; García, Maria-Sonia G; Banga, Julio R; Alonso, Antonio A
2012-07-02
Systems biology allows the analysis of biological systems behavior under different conditions through in silico experimentation. The possibility of perturbing biological systems in different manners calls for the design of perturbations to achieve particular goals. Examples would include, the design of a chemical stimulation to maximize the amplitude of a given cellular signal or to achieve a desired pattern in pattern formation systems, etc. Such design problems can be mathematically formulated as dynamic optimization problems which are particularly challenging when the system is described by partial differential equations.This work addresses the numerical solution of such dynamic optimization problems for spatially distributed biological systems. The usual nonlinear and large scale nature of the mathematical models related to this class of systems and the presence of constraints on the optimization problems, impose a number of difficulties, such as the presence of suboptimal solutions, which call for robust and efficient numerical techniques. Here, the use of a control vector parameterization approach combined with efficient and robust hybrid global optimization methods and a reduced order model methodology is proposed. The capabilities of this strategy are illustrated considering the solution of a two challenging problems: bacterial chemotaxis and the FitzHugh-Nagumo model. In the process of chemotaxis the objective was to efficiently compute the time-varying optimal concentration of chemotractant in one of the spatial boundaries in order to achieve predefined cell distribution profiles. Results are in agreement with those previously published in the literature. The FitzHugh-Nagumo problem is also efficiently solved and it illustrates very well how dynamic optimization may be used to force a system to evolve from an undesired to a desired pattern with a reduced number of actuators. The presented methodology can be used for the efficient dynamic optimization of
Eruption cycles in a basaltic andesite system: insights from numerical modeling
Smekens, J. F.; Clarke, A. B.; De'Michieli Vitturi, M.
2015-12-01
Persistently active explosive volcanoes are characterized by short explosive bursts, which often occur at periodic intervals numerous times per day, spanning years to decades. Many of these systems present relatively evolved compositions (andesite to rhyolite), and their cyclic activity has been the subject of extensive work (e.g., Soufriere Hills Volcano, Montserrat). However, the same periodic behavior can also be observed at open systems of more mafic compositions, such as Semeru in Indonesia or Karymsky in Kamchatka for example. In this work, we use DOMEFLOW, a 1D transient numerical model of magma ascent, to identify the conditions that lead to and control periodic eruptions in basaltic andesite systems, where the viscosity of the liquid phase can be drastically lower. Periodic behavior occurs for a very narrow range of conditions, for which the mass balance between magma flux and open-system gas escape repeatedly generates a viscous plug, pressurizes the magma beneath the plug, and then explosively disrupts it. The characteristic timescale and magnitude of the eruptive cycles are controlled by the overall viscosity of the magmatic mixture, with higher viscosities leading to longer cycles and lower flow rates at the top of the conduit. Cyclic eruptions in basaltic andesite systems are observed for higher crystal contents, smaller conduit radii, and over a wider range of chamber pressures than the andesitic system, all of which are the direct consequence of a decrease in viscosity of the melt phase, and in turn in the intensity of the viscous forces generated by the system. Results suggest that periodicity can exist in more mafic systems with relatively lower chamber pressures than andesite and rhyolite systems, and may explain why more mafic magmas sometimes remain active for decades.
International Nuclear Information System (INIS)
Han, Sang Mok; Hwang, Young Kyu; Kim, Dong Kwon
2015-01-01
Contamination in a clean room may appear even more complicated by the effect of complicated manufacturing processes and indoor equipment. For this reason, detailed information about the concentration of pollutant particles in the clean room is needed to control the level of contamination financially and efficiently without any problem in manufacturing process. Allocation method has been developed as one of main ideas to fulfill a function of controlling contamination under the situation. By using this method, weighting factor can be predicted based on cleanliness on sampling spots and the values based on numerical analysis. In this point, the weighting factor indicates how each of contaminant sources influences the concentration of pollutant in the clean room. In this paper, when applied allocation method, we propose zoning method to accelerate the calculation time. And it was applied to cleanliness the actual improvement of the turbulent type clean room. As a result, we could estimate quantitatively the amount of contamination generated from the pollution sources. And was proved by experiments that it is possible to improve the level of cleanliness of the clean rooms by using these results.
Directory of Open Access Journals (Sweden)
Kuligowska Ewa
2017-06-01
Full Text Available The material given in this paper delivers the procedure for numerical approach that allows finding the main practically important safety characteristics of the complex technical systems at the variable operation conditions including operating environment threats. The obtained results are applied to the safety evaluation of the maritime ferry technical system. It is assumed that the conditional safety functions are different at various operation states and have the exponential forms. Using the procedure and the program written in Mathematica, the considered maritime ferry technical system main characteristics including: the conditional and the unconditional expected values and standard deviations of the system lifetimes, the unconditional safety function and the risk function are determined.
Numerical analysis of a natural convection cooling system for radioactive canisters storage
Energy Technology Data Exchange (ETDEWEB)
Tsal, R.J.; Anwar, S.; Mercada, M.G. [Fluor Daniel Inc., Irvine, CA (United States)
1995-02-01
This paper describes the use of numerical analysis for studying natural convection cooling systems for long term storage of heat producing radioactive materials, including special nuclear materials and nuclear waste. The paper explains the major design philosophy, and shares the experiences of numerical modeling. The strategy of storing radioactive material is to immobilize nuclear high-level waste by a vitrification process, convertion it into borosilicate glass, and cast the glass into stainless steel canisters. These canisters are seal welded, decontaminated, inspected, and temporarily stored in an underground vault until they can be sent to a geologic repository for permanent storage. These canisters generate heat by nuclear decay of radioactive isotopes. The function of the storage facility ventilation system is to ensure that the glass centerline temperature does not exceed the glass transition temperature during storage and the vault concrete temperatures remain within the specified limits. A natural convection cooling system was proposed to meet these functions. The effectiveness of a natural convection cooling system is dependent on two major factors that affect air movement through the vault for cooling the canisters: (1) thermal buoyancy forces inside the vault which create a stack effect, and (2) external wind forces, that may assist or oppose airflow through the vault. Several numerical computer models were developed to analyze the thermal and hydraulic regimes in the storage vault. The Site Model is used to simulate the airflow around the building and to analyze different air inlet/outlet devices. The Airflow Model simulates the natural convection, thermal regime, and hydraulic resistance in the vault. The Vault Model, internal vault temperature stratification; and, finally, the Hot Area Model is used for modeling concrete temperatures within the vault.
Numerical analysis on the performance of solar chimney power plant system
International Nuclear Information System (INIS)
Xu Guoliang; Ming Tingzhen; Pan Yuan; Meng Fanlong; Zhou Cheng
2011-01-01
Power generating technology based on renewable energy resources will definitely become a new trend of future energy utilization. Numerical simulations on air flow, heat transfer and power output characteristics of a solar chimney power plant model with energy storage layer and turbine similar to the Spanish prototype were carried out in this paper, and mathematical model of flow and heat transfer for the solar chimney power plant system was established. The influences of solar radiation and pressure drop across the turbine on the flow and heat transfer, output power and energy loss of the solar chimney power plant system were analyzed. The numerical simulation results reveal that: when the solar radiation and the turbine efficiency are 600 W/m 2 and 80%, respectively, the output power of the system can reach 120 kW. In addition, large mass flow rate of air flowing through the chimney outlet become the main cause of energy loss in the system, and the collector canopy also results in large energy loss.
Directory of Open Access Journals (Sweden)
Daniel Ventura
2010-01-01
Full Text Available The lambda-calculus with de Bruijn indices assembles each alpha-class of lambda-terms in a unique term, using indices instead of variable names. Intersection types provide finitary type polymorphism and can characterise normalisable lambda-terms through the property that a term is normalisable if and only if it is typeable. To be closer to computations and to simplify the formalisation of the atomic operations involved in beta-contractions, several calculi of explicit substitution were developed mostly with de Bruijn indices. Versions of explicit substitutions calculi without types and with simple type systems are well investigated in contrast to versions with more elaborate type systems such as intersection types. In previous work, we introduced a de Bruijn version of the lambda-calculus with an intersection type system and proved that it preserves subject reduction, a basic property of type systems. In this paper a version with de Bruijn indices of an intersection type system originally introduced to characterise principal typings for beta-normal forms is presented. We present the characterisation in this new system and the corresponding versions for the type inference and the reconstruction of normal forms from principal typings algorithms. We briefly discuss the failure of the subject reduction property and some possible solutions for it.
Avellar, J.; Duarte, L. G. S.; da Mota, L. A. C. P.; de Melo, N.; Skea, J. E. F.
2012-09-01
A set of Maple routines is presented, fully compatible with the new releases of Maple (14 and higher). The package deals with the numerical evolution of dynamical systems and provide flexible plotting of the results. The package also brings an initial conditions generator, a numerical solver manager, and a focusing set of routines that allow for better analysis of the graphical display of the results. The novelty that the package presents an optional C interface is maintained. This allows for fast numerical integration, even for the totally inexperienced Maple user, without any C expertise being required. Finally, the package provides the routines to calculate the fractal dimension of boundaries (via box counting). New version program summary Program Title: Ndynamics Catalogue identifier: %Leave blank, supplied by Elsevier. Licensing provisions: no. Programming language: Maple, C. Computer: Intel(R) Core(TM) i3 CPU M330 @ 2.13 GHz. Operating system: Windows 7. RAM: 3.0 GB Keywords: Dynamical systems, Box counting, Fractal dimension, Symbolic computation, Differential equations, Maple. Classification: 4.3. Catalogue identifier of previous version: ADKH_v1_0. Journal reference of previous version: Comput. Phys. Commun. 119 (1999) 256. Does the new version supersede the previous version?: Yes. Nature of problem Computation and plotting of numerical solutions of dynamical systems and the determination of the fractal dimension of the boundaries. Solution method The default method of integration is a fifth-order Runge-Kutta scheme, but any method of integration present on the Maple system is available via an argument when calling the routine. A box counting [1] method is used to calculate the fractal dimension [2] of the boundaries. Reasons for the new version The Ndynamics package met a demand of our research community for a flexible and friendly environment for analyzing dynamical systems. All the user has to do is create his/her own Maple session, with the system to
Enbridge system : crude types, transportation and handling systems
Energy Technology Data Exchange (ETDEWEB)
Anand, A. [Enbridge Corp., Edmonton, AB (Canada)
2009-07-01
The supply of crude oil from the Western Canada Sedimentary Basin is expected to increase by approximately 2.1 million barrels per day by 2015. The crudes that Enbridge handles range from 19 API to 40 API and 0.1 per cent sulphur to 4.7 per cent sulphur. The diverse supply of crude oil that the Enbridge system handles includes conventional heavy, synthetic heavy, heavy high tan, heavy low residual, medium, light sour, heavy sour, light sweet, light sweet synthetic, condensate and olefinic crudes. This presentation discussed Enbridge's plans for infrastructure expansion, crude types and quality assurance program. The company's infrastructure plans include the expansion of regional pipelines to bring more supplies to the mainline; expansion of the mainline capacity to existing markets; and providing pipeline access to new markets. Merchant storage terminals will be provided in some locations. The quality of various crude types will be maintained through judicious sequencing and tank bottoms crossings. tabs., figs.
Numerical simulation of X-wing type biplane flapping wings in 3D using the immersed boundary method
International Nuclear Information System (INIS)
Tay, W B; Van Oudheusden, B W; Bijl, H
2014-01-01
The numerical simulation of an insect-sized ‘X-wing’ type biplane flapping wing configuration is performed in 3D using an immersed boundary method solver at Reynolds numbers equal to 1000 (1 k) and 5 k, based on the wing's root chord length. This X-wing type flapping configuration draws its inspiration from Delfly, a bio-inspired ornithopter MAV which has two pairs of wings flapping in anti-phase in a biplane configuration. The objective of the present investigation is to assess the aerodynamic performance when the original Delfly flapping wing micro-aerial vehicle (FMAV) is reduced to the size of an insect. Results show that the X-wing configuration gives more than twice the average thrust compared with only flapping the upper pair of wings of the X-wing. However, the X-wing's average thrust is only 40% that of the upper wing flapping at twice the stroke angle. Despite this, the increased stability which results from the smaller lift and moment variation of the X-wing configuration makes it more suited for sharp image capture and recognition. These advantages make the X-wing configuration an attractive alternative design for insect-sized FMAVS compared to the single wing configuration. In the Reynolds number comparison, the vorticity iso-surface plot at a Reynolds number of 5 k revealed smaller, finer vortical structures compared to the simulation at 1 k, due to vortices’ breakup. In comparison, the force output difference is much smaller between Re = 1 k and 5 k. Increasing the body inclination angle generates a uniform leading edge vortex instead of a conical one along the wingspan, giving higher lift. Understanding the force variation as the body inclination angle increases will allow FMAV designers to optimize the thrust and lift ratio for higher efficiency under different operational requirements. Lastly, increasing the spanwise flexibility of the wings increases the thrust slightly but decreases the efficiency. The thrust result is similar
Information system conflicts : causes and types
Boonstra, Albert; de Vries, Jan
2015-01-01
Conflicts are an inherent part of organizational life and managers deal with confrontations and conflicts on an almost daily basis. IS implementations are a type of change that often leads to open or hidden conflicts. Managers and others involved can only deal with such conflicts effectively if they
A type system for Continuation Calculus
Directory of Open Access Journals (Sweden)
Herman Geuvers
2014-09-01
Full Text Available Continuation Calculus (CC, introduced by Geron and Geuvers, is a simple foundational model for functional computation. It is closely related to lambda calculus and term rewriting, but it has no variable binding and no pattern matching. It is Turing complete and evaluation is deterministic. Notions like "call-by-value" and "call-by-name" computation are available by choosing appropriate function definitions: e.g. there is a call-by-value and a call-by-name addition function. In the present paper we extend CC with types, to be able to define data types in a canonical way, and functions over these data types, defined by iteration. Data type definitions follow the so-called "Scott encoding" of data, as opposed to the more familiar "Church encoding". The iteration scheme comes in two flavors: a call-by-value and a call-by-name iteration scheme. The call-by-value variant is a double negation variant of call-by-name iteration. The double negation translation allows to move between call-by-name and call-by-value.
Numerical simulation of a 3-D flow within a storage area hexagonal modular pavement systems
International Nuclear Information System (INIS)
Rashid, M A; Abustan, I; Hamzah, M O
2013-01-01
This numerical study has been performed to predict the flow patterns and characteristics within a storage area Hexagonal Modular Pavement Systems. Throughout the design and planning period for future construction are increasingly integrating computational fluid dynamics (CFD) into the process. A commercially known software, FLOW-3D, is applied to numerically solve the Navier-stokes equations for solution domains which are separated into three regions with overlapping boundaries to efficiently accommodate the grid resolutions, namely the honeycomb shaped modular, gravel and combined honeycomb shaped modular with gravel fill. The filtration of the fluid within the interstices of a permeable pavement is evaluated by integrating the Reynolds Averaged Navier-Stokes equations (RANS) inside the voids rather than making use of the widespread porous media approach. In conclusion, the results from numerical simulation are generally well agreed with the existing data and flow information such as flow patterns at increased flow, discharge rate and pressure is obtained to be used for engineering design purpose. Overall, the potential for FLOW-3D to model various geometries and configurations appears great. It should be noted that CFD should not be considered a complete replacement for physical modelling; however, it can definitely be used as a supplementary tool throughout the pavement design process.
Solving the Bateman equations in CASMO5 using implicit ode numerical methods for stiff systems
International Nuclear Information System (INIS)
Hykes, J. M.; Ferrer, R. M.
2013-01-01
The Bateman equations, which describe the transmutation of nuclides over time as a result of radioactive decay, absorption, and fission, are often numerically stiff. This is especially true if short-lived nuclides are included in the system. This paper describes the use of implicit numerical methods for o D Es applied to the stiff Bateman equations, specifically employing the Backward Differentiation Formulas (BDF) form of the linear multistep method. As is true in other domains, using an implicit method removes or lessens the (sometimes severe) step-length constraints by which explicit methods must abide. To gauge its accuracy and speed, the BDF method is compared to a variety of other solution methods, including Runge-Kutta explicit methods and matrix exponential methods such as the Chebyshev Rational Approximation Method (CRAM). A preliminary test case was chosen as representative of a PWR lattice depletion step and was solved with numerical libraries called from a Python front-end. The Figure of Merit (a combined measure of accuracy and efficiency) for the BDF method was nearly identical to that for CRAM, while explicit methods and other matrix exponential approximations trailed behind. The test case includes 319 nuclides, in which the shortest-lived nuclide is 98 Nb with a half-life of 2.86 seconds. Finally, the BDF and CRAM methods were compared within CASMO5, where CRAM had a FOM about four times better than BDF, although the BDF implementation was not fully optimized. (authors)
Numerical investigation of passive heat removal system via steam generator in VVER 1200
International Nuclear Information System (INIS)
Dinh Anh Tuan; Duong Thanh Tung; Tran Chi Thanh; Nguyen Van Thai
2015-01-01
Passive heat removal system (PHRS) via Steam Generator is an important part in VVER design. In case of Design Basic Accidents such as blackout, failure of feed water supply to steam generator or coolant leakage with failure of emergency core cooling at high pressure. PHRS is designed to remove the residual heat from reactor core through steam generator to heat exchanger which is placed outside reactor vessel. In order to evaluate the passive system, a numerical investigation using a CFD code is performed. However, PHRS has complex geometry for using CFD simulation. Thus, RELAP5 is applied to provide the wall heat flux of tube in the heat exchanger tank. The natural convection in the heat exchanger tank is investigated in this report. Numerical results show temperature and velocity distribution in the heat exchanger tank are calculated with different wall heat flux corresponding to various transient conditions. The calculated results contribute to the capacity analysis of passive heat removal system and giving valuable information for safe operation of VVER 1200. (author)
Numerical viscosity of entropy stable schemes for systems of conservation laws. Final Report
International Nuclear Information System (INIS)
Tadmor, E.
1985-11-01
Discrete approximations to hyperbolic systems of conservation laws are studied. The amount of numerical viscosity present in such schemes is quantified and related to their entropy stability by means of comparison. To this end conservative schemes which are also entropy conservative are constructed. These entropy conservative schemes enjoy second-order accuracy; moreover, they admit a particular interpretation within the finite-element frameworks, and hence can be formulated on various mesh configurations. It is then shown that conservative schemes are entropy stable if and only if they contain more viscosity than the mentioned above entropy conservative ones
Long-time behavior in numerical solutions of certain dynamical systems
International Nuclear Information System (INIS)
Vazquez, L.
1987-01-01
A general discretization of the ordinary nonlinear differential equations d 2 v/dt 2 =f(v) and dv/dt=g(v) is studied. The discrete scheme conserves the discrete analogous of a quantity that is conserved by the corresponding equations. This method is applied to two cases and no ''ghost solutions'' were observed for the long range calculation. In these cases we analyze the stability of the corresponding numerical scheme as a dynamical system and in the sense studied by Kuo Pen-Yu and Stetter. In particular we find a correspondence between both kinds of stability. (author)
Numerical analysis of natural convection in a double-layer immiscible system
International Nuclear Information System (INIS)
Gubaidullin, A.A.; Sehgal, B.R.
2001-01-01
In the present paper numerical analysis has been applied to study the natural convection heat transfer in a system composed of two immiscible fluids with uniform internal heat generation in the lower layer or in both layers enclosed in a rectangular or in a semi-circular vessel. The objective of the work is to perform a parametric study to assess the effect of physical properties on the heat transfer characteristics as well as to complement results obtained from experiments by means of CFD simulations for a range of lower Rayleigh number and combine the experimental data and the computational results. (author)
A program for the numerical control of a pulse increment system
Energy Technology Data Exchange (ETDEWEB)
Gray, D.C.
1963-08-21
This report will describe the important features of the development of magnetic tapes for the numerical control of a pulse-increment system consisting of a modified Gorton lathe and its associated control unit developed by L. E. Foley of Equipment Development Service, Engineering Services, General Electric Co., Schenectady, N.Y. Included is a description of CUPID (Control and Utilization of Pulse Increment Devices), a FORTRAN program for the design of these tapes on the IBM 7090 computer, and instructions for its operation.
The numerical solution of linear multi-term fractional differential equations: systems of equations
Edwards, John T.; Ford, Neville J.; Simpson, A. Charles
2002-11-01
In this paper, we show how the numerical approximation of the solution of a linear multi-term fractional differential equation can be calculated by reduction of the problem to a system of ordinary and fractional differential equations each of order at most unity. We begin by showing how our method applies to a simple class of problems and we give a convergence result. We solve the Bagley Torvik equation as an example. We show how the method can be applied to a general linear multi-term equation and give two further examples.
3D NUMERICAL STUDY OF FLOW IN A SOLAR CHIMNEY POWER PLANT SYSTEM
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TAHAR TAYEBI
2015-12-01
Full Text Available Heat transfer process and fluid flow in a Solar Chimney Power Plant System (SCPPS are investigated numerically. As simulation object we use the Spanish prototype plant. The calculative model and boundary conditions in calculation are introduced. Boussinesq model was chosen in the natural convection processus, Discrete Ordinate radiation model was employed for radiation. The principal factors that influence on the performance of the Solar Chimney have been analysed. The effects on the flow of the Solar Chimney which caused by solar radiation intensity have been simulated. The calculated results are compared and are approximately equivalent to the relative experimental data of the Manzanares prototype. It can be concluded that the temperature difference between the inlet and outlet of collector, as well as the air velocity in the collector of the system, is increase with the increase of solar radiation intensity and the pressure throughout system is negative value.
International Nuclear Information System (INIS)
Graf, U.
1986-01-01
A combination of several numerical methods is used to construct a procedure for effective calculation of complex three-dimensional fluid flow problems. The split coefficient matrix (SCM) method is used so that the differenced equations of the hyperbolic system do not disturb correct signal propagation. The semi-discretisation of the equations of the SCM method is done with the asymmetric, separated region, weighted residual (ASWR) method to give accurate solutions on a relatively coarse mesh. For the resulting system of ordinary differential equations, a general-purpose ordinary differential equation solver is used in conjunction with a method of fractional steps for an economic solution of the large system of linear equations. (orig.) [de
International Nuclear Information System (INIS)
Larroche, O.
2007-01-01
A locally split-step explicit (LSSE) algorithm was developed for efficiently solving a multi-dimensional advection-diffusion type equation involving a highly inhomogeneous and highly anisotropic diffusion tensor, which makes the problem very ill-conditioned for standard implicit methods involving the iterative solution of large linear systems. The need for such an optimized algorithm arises, in particular, in the frame of thermonuclear fusion applications, for the purpose of simulating fast charged-particle slowing-down with an ion Fokker-Planck code. The LSSE algorithm is presented in this paper along with the results of a model slowing-down problem to which it has been applied
Design of Parallel Air-Cooled Battery Thermal Management System through Numerical Study
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Kai Chen
2017-10-01
Full Text Available In electric vehicles, the battery pack is one of the most important components that strongly influence the system performance. The battery thermal management system (BTMS is critical to remove the heat generated by the battery pack, which guarantees the appropriate working temperature for the battery pack. Air cooling is one of the most commonly-used solutions among various battery thermal management technologies. In this paper, the cooling performance of the parallel air-cooled BTMS is improved through choosing appropriate system parameters. The flow field and the temperature field of the system are calculated using the computational fluid dynamics method. Typical numerical cases are introduced to study the influences of the operation parameters and the structure parameters on the performance of the BTMS. The operation parameters include the discharge rate of the battery pack, the inlet air temperature and the inlet airflow rate. The structure parameters include the cell spacing and the angles of the divergence plenum and the convergence plenum. The results show that the temperature rise and the temperature difference of the batter pack are not affected by the inlet air flow temperature and are increased as the discharge rate increases. Increasing the inlet airflow rate can reduce the maximum temperature, but meanwhile significantly increase the power consumption for driving the airflow. Adopting smaller cell spacing can reduce the temperature and the temperature difference of the battery pack, but it consumes much more power. Designing the angles of the divergence plenum and the convergence plenum is an effective way to improve the performance of the BTMS without occupying more system volume. An optimization strategy is used to obtain the optimal values of the plenum angles. For the numerical cases with fixed power consumption, the maximum temperature and the maximum temperature difference at the end of the five-current discharge process for
Experimental and numerical investigation of a scalable modular geothermal heat storage system
Nordbeck, Johannes; Bauer, Sebastian; Beyer, Christof
2017-04-01
Storage of heat will play a significant role in the transition towards a reliable and renewable power supply, as it offers a way to store energy from fluctuating and weather dependent energy sources like solar or wind power and thus better meet consumer demands. The focus of this study is the simulation-based design of a heat storage system, featuring a scalable and modular setup that can be integrated with new as well as existing buildings. For this, the system can be either installed in a cellar or directly in the ground. Heat supply is by solar collectors, and heat storage is intended at temperatures up to about 90°C, which requires a verification of the methods used for numerical simulation of such systems. One module of the heat storage system consists of a helical heat exchanger in a fully water saturated, high porosity cement matrix, which represents the heat storage medium. A lab-scale storage prototype of 1 m3 volume was set up in a thermally insulated cylinder equipped with temperature and moisture sensors as well as flux meters and temperature sensors at the inlet and outlet pipes in order to experimentally analyze the performance of the storage system. Furthermore, the experimental data was used to validate an accurate and spatially detailed high-resolution 3D numerical model of heat and fluid flow, which was developed for system design optimization with respect to storage efficiency and environmental impacts. Three experiments conducted so far are reported and analyzed in this work. The first experiment, consisting of cooling of the fully loaded heat storage by heat loss across the insulation, is designed to determine the heat loss and the insulation parameters, i.e. heat conductivity and heat capacity of the insulation, via inverse modelling of the cooling period. The average cooling rate experimentally found is 1.2 °C per day. The second experiment consisted of six days of thermal loading up to a storage temperature of 60°C followed by four days
Aldakheel, Fadi; Wriggers, Peter; Miehe, Christian
2017-12-01
The modeling of failure in ductile materials must account for complex phenomena at the micro-scale, such as nucleation, growth and coalescence of micro-voids, as well as the final rupture at the macro-scale, as rooted in the work of Gurson (J Eng Mater Technol 99:2-15, 1977). Within a top-down viewpoint, this can be achieved by the combination of a micro-structure-informed elastic-plastic model for a porous medium with a concept for the modeling of macroscopic crack discontinuities. The modeling of macroscopic cracks can be achieved in a convenient way by recently developed continuum phase field approaches to fracture, which are based on the regularization of sharp crack discontinuities, see Miehe et al. (Comput Methods Appl Mech Eng 294:486-522, 2015). This avoids the use of complex discretization methods for crack discontinuities, and can account for complex crack patterns. In this work, we develop a new theoretical and computational framework for the phase field modeling of ductile fracture in conventional elastic-plastic solids under finite strain deformation. It combines modified structures of Gurson-Tvergaard-Needelman GTN-type plasticity model outlined in Tvergaard and Needleman (Acta Metall 32:157-169, 1984) and Nahshon and Hutchinson (Eur J Mech A Solids 27:1-17, 2008) with a new evolution equation for the crack phase field. An important aspect of this work is the development of a robust Explicit-Implicit numerical integration scheme for the highly nonlinear rate equations of the enhanced GTN model, resulting with a low computational cost strategy. The performance of the formulation is underlined by means of some representative examples, including the development of the experimentally observed cup-cone failure mechanism.
International Nuclear Information System (INIS)
Emoto, M.; Suzuki, C.; Suzuki, Y.; Yokoyama, M.; Seki, R.; Ida, K.
2014-10-01
The enhanced-interlink system of experiment data and numerical simulation has been developed, and successfully operated routinely in the Large Helical Device (LHD). This system consists of analyzed diagnostic data, real-time coordinate mapping, and automatic data processing. It has enabled automated data handling/transferring between experiment and numerical simulation, to extensively perform experiment analyses. It can be considered as one of the prototypes for a seamless data-centric approach for integrating experiment data and numerical simulation/modellings in fusion experiments. Utilizing this system, experimental analyses by numerical simulations have extensively progressed. The authors believe this data-centric approach for integrating experiment data and numerical simulation/modellings will contribute to not only the LHD but to other plasma fusion projects including DEMO reactor in the future. (author)
Numerical simulation research of 300 kV, 5 electrodes negative ion beam system
International Nuclear Information System (INIS)
Wang Huisan; Jian Guangde
2001-01-01
According to the characteristic of high current negative ion beam extraction and acceleration system for negative ion-based neutral beam injector, a numerical simulation model and a calculation code of the negative ion beam system are established in order to assist the design of the system. The movement behavior of the negative ion beam and accompanying electron beam in joint effect of the electric and magnetic field of the system is calculated. The effect of relative parameters on the negative ion beam optics characteristic is investigated, such as beam density, negative ion initial temperature and stripping losses, final electrode aperture displacement. The electromagnetic configuration in the system is optimized. The initial optimized results for the 300 kV, 5 electrodes negative ion beam system show that the magnetic field of this system can deflect the electron beam to the extraction electrode as electron acceptor at lower energy and that assuming 20% stripping losses of the H - ion in extraction region and 21 mA ·cm -2 extracted H - beam density, the r.m.s. divergence angle of all output beam lets and divergence angle of 85% output beam lets are 0.327 deg. and 0.460 deg., respectively
Computational Analysis of Igbo Numerals in a Number-to-text Conversion System
Directory of Open Access Journals (Sweden)
Olufemi Deborah NINAN
2017-12-01
Full Text Available System for converting Arabic numerals to their textual equivalence is an important tool in Natural Language processing (NLP especially in high-level speech processing and machine translation. Such system is scarcely available for most African languages including the Igbo language. This translation system is essential as Igbo language is one of the three major Nigerian languages feared to be among the endangered African languages. The system was designed using sequence as well as activity diagram and implemented using the python programming language and PyQt. The qualitative evaluation was done by administering questionnaires to selected native Igbo speakers and experts to provide preferred representation of some random numbers. The responses were compared with the output of the system. The result of the qualitative evaluation showed that the system was able to generate correct and accurate representations for Arabic numbers between 1-1000 in Igbo language being the scope of this study. The resulting system can serve as an effective teaching and learning tool of the Igbo language.
International Nuclear Information System (INIS)
Kandelaki, Ervand
2014-01-01
This Thesis reports on the scientific research conducted in the field of theoretical condensed matter physics and covers two rather independent topics. First, three different projects targeting heterostructures involving superconductors are discussed. Then, a project related to numerical methods for general fermionic interacting systems is presented. The Thesis is divided into four parts. In Part I of the present Thesis, we study the variation in the differential conductance G = dj/dV of a normal metal wire in a superconductor/normal metal heterostructure with a cross geometry under external microwave radiation applied to the superconducting parts. Our theoretical treatment is based on the quasiclassical Green's functions technique in the diffusive limit. Two limiting cases are considered: first, the limit of a weak proximity effect and low microwave frequency and second, the limit of a short dimension (short normal wire) and small irradiation amplitude. In Part II, we study the dynamics of Josephson junctions with a thin ferromagnetic layer F [superconductor-ferromagnet-insulator-ferromagnet-superconductor (SFIFS) junctions]. In such junctions, the phase difference φ of the superconductors and magnetization M in the F layer are two dynamic parameters coupled to each other. We derive equations describing the dynamics of these two parameters and formulate the conditions of validity. The coupled Josephson plasma waves and oscillations of the magnetization M affect the form of the current-voltage (I - V) characteristics in the presence of a weak magnetic field (Fiske steps). We calculate the modified Fiske steps and show that the magnetic degree of freedom not only changes the form of the Fiske steps but also the overall view of the I - V curve (new peaks related to the magnetic resonance appear). The I - V characteristics are shown for different lengths of the junction including those which correspond to the current experimental situation. We also calculate the
Energy Technology Data Exchange (ETDEWEB)
Kandelaki, Ervand
2014-11-25
This Thesis reports on the scientific research conducted in the field of theoretical condensed matter physics and covers two rather independent topics. First, three different projects targeting heterostructures involving superconductors are discussed. Then, a project related to numerical methods for general fermionic interacting systems is presented. The Thesis is divided into four parts. In Part I of the present Thesis, we study the variation in the differential conductance G = dj/dV of a normal metal wire in a superconductor/normal metal heterostructure with a cross geometry under external microwave radiation applied to the superconducting parts. Our theoretical treatment is based on the quasiclassical Green's functions technique in the diffusive limit. Two limiting cases are considered: first, the limit of a weak proximity effect and low microwave frequency and second, the limit of a short dimension (short normal wire) and small irradiation amplitude. In Part II, we study the dynamics of Josephson junctions with a thin ferromagnetic layer F [superconductor-ferromagnet-insulator-ferromagnet-superconductor (SFIFS) junctions]. In such junctions, the phase difference φ of the superconductors and magnetization M in the F layer are two dynamic parameters coupled to each other. We derive equations describing the dynamics of these two parameters and formulate the conditions of validity. The coupled Josephson plasma waves and oscillations of the magnetization M affect the form of the current-voltage (I - V) characteristics in the presence of a weak magnetic field (Fiske steps). We calculate the modified Fiske steps and show that the magnetic degree of freedom not only changes the form of the Fiske steps but also the overall view of the I - V curve (new peaks related to the magnetic resonance appear). The I - V characteristics are shown for different lengths of the junction including those which correspond to the current experimental situation. We also calculate the
Development of a phage typing system for Staphylococcus hyicus
DEFF Research Database (Denmark)
Wegener, Henrik Caspar
1993-01-01
Bacteriophages were released by 98% of 100 Staphylococcus hyicus strains studied after treatment with mitomycin C. Twenty-three phages with different lytic spectra were included in a phage typing system and used f or typing S. hyicus. On a test-set of 100 epidemiologically unrelated S. hyicus...... strains isolated from Danish pig herds, the phages were able to type 92% of the strains, producing 16 different phage types. Reproducibility of the phage typing system after subculture of the strains and using fresh phage stock was 96%. Typability ranged from 52 to 80% when typing porcine strains...... originating from other countries. Although phages were isolated from porcine skin strains exclusively, the system produced phage types in S. hyicus strains of bovine origin. Ten strains of S. aureus and S. chromogenes were not typable by these phages. Strains belonging to one phage type (A/B/C/W) were...
Numerical Treatment of the Boltzmann Equation for Self-Propelled Particle Systems
Directory of Open Access Journals (Sweden)
Florian Thüroff
2014-11-01
Full Text Available Kinetic theories constitute one of the most promising tools to decipher the characteristic spatiotemporal dynamics in systems of actively propelled particles. In this context, the Boltzmann equation plays a pivotal role, since it provides a natural translation between a particle-level description of the system’s dynamics and the corresponding hydrodynamic fields. Yet, the intricate mathematical structure of the Boltzmann equation substantially limits the progress toward a full understanding of this equation by solely analytical means. Here, we propose a general framework to numerically solve the Boltzmann equation for self-propelled particle systems in two spatial dimensions and with arbitrary boundary conditions. We discuss potential applications of this numerical framework to active matter systems and use the algorithm to give a detailed analysis to a model system of self-propelled particles with polar interactions. In accordance with previous studies, we find that spatially homogeneous isotropic and broken-symmetry states populate two distinct regions in parameter space, which are separated by a narrow region of spatially inhomogeneous, density-segregated moving patterns. We find clear evidence that these three regions in parameter space are connected by first-order phase transitions and that the transition between the spatially homogeneous isotropic and polar ordered phases bears striking similarities to liquid-gas phase transitions in equilibrium systems. Within the density-segregated parameter regime, we find a novel stable limit-cycle solution of the Boltzmann equation, which consists of parallel lanes of polar clusters moving in opposite directions, so as to render the overall symmetry of the system’s ordered state nematic, despite purely polar interactions on the level of single particles.
International Nuclear Information System (INIS)
Lode, Axel U.J.
2013-01-01
This thesis explores the quantum many-body tunneling dynamics of open ultracold bosonic systems with the recently developed multiconfigurational time-dependent Hartree for bosons (MCTDHB) method. The capabilities of MCTDHB to provide solutions to the full time-dependent many-body problem are assessed in a benchmark using the analytically solvable harmonic interaction Hamiltonian and a generalization of it with time-dependent both one- and two-body potentials. In a comparison with numerically exact MCTDHB results, it is shown that e.g. lattice methods fail qualitatively to describe the tunneling dynamics. A model assembling the many-body physics of the process from basic simultaneously happening single-particle processes is derived and verified with a numerically exact MCTDHB description. The generality of the model is demonstrated even for strong interactions and large particle numbers. The ejection of the bosons from the source occurs with characteristic velocities. These velocities are defined by the chemical potentials of systems with different particle numbers which are converted to kinetic energy. The tunneling process is accompanied by fragmentation: the ejected bosons lose their coherence with the source and among each other. It is shown that the various aspects of the tunneling dynamics' can be controlled well with the interaction and the potential threshold.
A faster numerical scheme for a coupled system modeling soil erosion and sediment transport
Le, M.-H.; Cordier, S.; Lucas, C.; Cerdan, O.
2015-02-01
Overland flow and soil erosion play an essential role in water quality and soil degradation. Such processes, involving the interactions between water flow and the bed sediment, are classically described by a well-established system coupling the shallow water equations and the Hairsine-Rose model. Numerical approximation of this coupled system requires advanced methods to preserve some important physical and mathematical properties; in particular, the steady states and the positivity of both water depth and sediment concentration. Recently, finite volume schemes based on Roe's solver have been proposed by Heng et al. (2009) and Kim et al. (2013) for one and two-dimensional problems. In their approach, an additional and artificial restriction on the time step is required to guarantee the positivity of sediment concentration. This artificial condition can lead the computation to be costly when dealing with very shallow flow and wet/dry fronts. The main result of this paper is to propose a new and faster scheme for which only the CFL condition of the shallow water equations is sufficient to preserve the positivity of sediment concentration. In addition, the numerical procedure of the erosion part can be used with any well-balanced and positivity preserving scheme of the shallow water equations. The proposed method is tested on classical benchmarks and also on a realistic configuration.
Directory of Open Access Journals (Sweden)
Shuai Sun
2018-01-01
Full Text Available In order to analyze the characteristics of propeller exciting force, the hybrid grid is adopted and the numerical prediction of KCS ship model is performed for hull–propeller–rudder system by Reynolds-Averaged Navier Stokes (RANS method and volume of fluid (VOF model. Firstly, the numerical simulation of hydrodynamics for bare hull at oblique state is carried out. The results show that with the increasing of the drift angle, the coefficients of resistance, side force and yaw moment are constantly increasing, and the bigger the drift angle, the worse the overall uniformity of propeller disk. Then, propeller bearing force for hull–propeller–rudder system in oblique flow is calculated. It is found that the propeller thrust and torque fluctuation coefficient peak in drift angle are greater than that in straight line navigation, and the negative drift angle is greater than the positive. The fluctuation peak variation law of coefficient of side force and bending moment are different due to various causes.
Huang, Jie; Li, Piao; Yao, Weixing
2018-05-01
A loosely coupled fluid-structural thermal numerical method is introduced for the thermal protection system (TPS) gap thermal control analysis in this paper. The aerodynamic heating and structural thermal are analyzed by computational fluid dynamics (CFD) and numerical heat transfer (NHT) methods respectively. An interpolation algorithm based on the control surface is adopted for the data exchanges on the coupled surface. In order to verify the analysis precision of the loosely coupled method, a circular tube example was analyzed, and the wall temperature agrees well with the test result. TPS gap thermal control performance was studied by the loosely coupled method successfully. The gap heat flux is mainly distributed in the small region at the top of the gap which is the high temperature region. Besides, TPS gap temperature and the power of the active cooling system (CCS) calculated by the traditional uncoupled method are higher than that calculated by the coupled method obviously. The reason is that the uncoupled method doesn't consider the coupled effect between the aerodynamic heating and structural thermal, however the coupled method considers it, so TPS gap thermal control performance can be analyzed more accurately by the coupled method.
Hu, Shaoxing; Xu, Shike; Wang, Duhu; Zhang, Aiwu
2015-11-11
Aiming at addressing the problem of high computational cost of the traditional Kalman filter in SINS/GPS, a practical optimization algorithm with offline-derivation and parallel processing methods based on the numerical characteristics of the system is presented in this paper. The algorithm exploits the sparseness and/or symmetry of matrices to simplify the computational procedure. Thus plenty of invalid operations can be avoided by offline derivation using a block matrix technique. For enhanced efficiency, a new parallel computational mechanism is established by subdividing and restructuring calculation processes after analyzing the extracted "useful" data. As a result, the algorithm saves about 90% of the CPU processing time and 66% of the memory usage needed in a classical Kalman filter. Meanwhile, the method as a numerical approach needs no precise-loss transformation/approximation of system modules and the accuracy suffers little in comparison with the filter before computational optimization. Furthermore, since no complicated matrix theories are needed, the algorithm can be easily transplanted into other modified filters as a secondary optimization method to achieve further efficiency.
Jahantigh, Nabi; Keshavarz, Ali; Mirzaei, Masoud
2015-01-01
The aim of this study is to determine optimum hybrid heating systems parameters, such as temperature, surface area of a radiant heater and vent area to have thermal comfort conditions. DOE, Factorial design method is used to determine the optimum values for input parameters. A 3D model of a virtual standing thermal manikin with real dimensions is considered in this study. Continuity, momentum, energy, species equations for turbulent flow and physiological equation for thermal comfort are numerically solved to study heat, moisture and flow field. K - ɛRNG Model is used for turbulence modeling and DO method is used for radiation effects. Numerical results have a good agreement with the experimental data reported in the literature. The effect of various combinations of inlet parameters on thermal comfort is considered. According to Pareto graph, some of these combinations that have significant effect on the thermal comfort require no more energy can be used as useful tools. A better symmetrical velocity distribution around the manikin is also presented in the hybrid system.
Numerical simulation of stochastic point kinetic equation in the dynamical system of nuclear reactor
International Nuclear Information System (INIS)
Saha Ray, S.
2012-01-01
Highlights: ► In this paper stochastic neutron point kinetic equations have been analyzed. ► Euler–Maruyama method and Strong Taylor 1.5 order method have been discussed. ► These methods are applied for the solution of stochastic point kinetic equations. ► Comparison between the results of these methods and others are presented in tables. ► Graphs for neutron and precursor sample paths are also presented. -- Abstract: In the present paper, the numerical approximation methods, applied to efficiently calculate the solution for stochastic point kinetic equations () in nuclear reactor dynamics, are investigated. A system of Itô stochastic differential equations has been analyzed to model the neutron density and the delayed neutron precursors in a point nuclear reactor. The resulting system of Itô stochastic differential equations are solved over each time-step size. The methods are verified by considering different initial conditions, experimental data and over constant reactivities. The computational results indicate that the methods are simple and suitable for solving stochastic point kinetic equations. In this article, a numerical investigation is made in order to observe the random oscillations in neutron and precursor population dynamics in subcritical and critical reactors.
A numerical integration approach suitable for simulating PWR dynamics using a microcomputer system
International Nuclear Information System (INIS)
Zhiwei, L.; Kerlin, T.W.
1983-01-01
It is attractive to use microcomputer systems to simulate nuclear power plant dynamics for the purpose of teaching and/or control system design. An analysis and a comparison of feasibility of existing numerical integration methods have been made. The criteria for choosing the integration step using various numerical integration methods including the matrix exponential method are derived. In order to speed up the simulation, an approach is presented using the Newton recursion calculus which can avoid convergence limitations in choosing the integration step size. The accuracy consideration will dominate the integration step limited. The advantages of this method have been demonstrated through a case study using CBM model 8032 microcomputer to simulate a reduced order linear PWR model under various perturbations. It has been proven theoretically and practically that the Runge-Kutta method and Adams-Moulton method are not feasible. The matrix exponential method is good at accuracy and fairly good at speed. The Newton recursion method can save 3/4 to 4/5 time compared to the matrix exponential method with reasonable accuracy. Vertical Barhis method can be expanded to deal with nonlinear nuclear power plant models and higher order models as well
Energy Technology Data Exchange (ETDEWEB)
Lode, Axel U.J.
2013-06-03
This thesis explores the quantum many-body tunneling dynamics of open ultracold bosonic systems with the recently developed multiconfigurational time-dependent Hartree for bosons (MCTDHB) method. The capabilities of MCTDHB to provide solutions to the full time-dependent many-body problem are assessed in a benchmark using the analytically solvable harmonic interaction Hamiltonian and a generalization of it with time-dependent both one- and two-body potentials. In a comparison with numerically exact MCTDHB results, it is shown that e.g. lattice methods fail qualitatively to describe the tunneling dynamics. A model assembling the many-body physics of the process from basic simultaneously happening single-particle processes is derived and verified with a numerically exact MCTDHB description. The generality of the model is demonstrated even for strong interactions and large particle numbers. The ejection of the bosons from the source occurs with characteristic velocities. These velocities are defined by the chemical potentials of systems with different particle numbers which are converted to kinetic energy. The tunneling process is accompanied by fragmentation: the ejected bosons lose their coherence with the source and among each other. It is shown that the various aspects of the tunneling dynamics' can be controlled well with the interaction and the potential threshold.
Acri, Antonio; Offner, Guenter; Nijman, Eugene; Rejlek, Jan
2016-10-01
Noise legislations and the increasing customer demands determine the Noise Vibration and Harshness (NVH) development of modern commercial vehicles. In order to meet the stringent legislative requirements for the vehicle noise emission, exact knowledge of all vehicle noise sources and their acoustic behavior is required. Transfer path analysis (TPA) is a fairly well established technique for estimating and ranking individual low-frequency noise or vibration contributions via the different transmission paths. Transmission paths from different sources to target points of interest and their contributions can be analyzed by applying TPA. This technique is applied on test measurements, which can only be available on prototypes, at the end of the designing process. In order to overcome the limits of TPA, a numerical transfer path analysis methodology based on the substructuring of a multibody system is proposed in this paper. Being based on numerical simulation, this methodology can be performed starting from the first steps of the designing process. The main target of the proposed methodology is to get information of noise sources contributions of a dynamic system considering the possibility to have multiple forces contemporary acting on the system. The contributions of these forces are investigated with particular focus on distribute or moving forces. In this paper, the mathematical basics of the proposed methodology and its advantages in comparison with TPA will be discussed. Then, a dynamic system is investigated with a combination of two methods. Being based on the dynamic substructuring (DS) of the investigated model, the methodology proposed requires the evaluation of the contact forces at interfaces, which are computed with a flexible multi-body dynamic (FMBD) simulation. Then, the structure-borne noise paths are computed with the wave based method (WBM). As an example application a 4-cylinder engine is investigated and the proposed methodology is applied on the
Coolant cleanup system for BWR type reactor
International Nuclear Information System (INIS)
Kinoshita, Shoichiro; Araki, Hidefumi.
1993-01-01
The cleanup system of the present invention removes impurity ions and floating materials accumulated in a reactor during evaporation of coolants in the nuclear reactor. That is, coolants pass pipelines from a pressure vessel using pressure difference between a high pressure in the pressure vessel and a low pressure at the upstream of a condensate filtration/desalting device of a condensate/feed water system as a driving source, during which cations and floating materials are removed in a high temperature filtration/desalting device and coolants flow into the condensate/feedwater system. Impurities containing anions are removed here by the condensates filtration/desalting device. Then, they return to the pressure vessel while pressurized and heated by a condensate pump, a feed water pump and a feed water heater. At least pumps, a heat exchanger for heating, a filtration/desalting device for removing anions and pipelines connecting them used exclusively for the coolant cleanup system are no more necessary. (I.S.)
Numerical modelling of series-parallel cooling systems in power plant
Directory of Open Access Journals (Sweden)
Regucki Paweł
2017-01-01
Full Text Available The paper presents a mathematical model allowing one to study series-parallel hydraulic systems like, e.g., the cooling system of a power boiler's auxiliary devices or a closed cooling system including condensers and cooling towers. The analytical approach is based on a set of non-linear algebraic equations solved using numerical techniques. As a result of the iterative process, a set of volumetric flow rates of water through all the branches of the investigated hydraulic system is obtained. The calculations indicate the influence of changes in the pipeline's geometrical parameters on the total cooling water flow rate in the analysed installation. Such an approach makes it possible to analyse different variants of the modernization of the studied systems, as well as allowing for the indication of its critical elements. Basing on these results, an investor can choose the optimal variant of the reconstruction of the installation from the economic point of view. As examples of such a calculation, two hydraulic installations are described. One is a boiler auxiliary cooling installation including two screw ash coolers. The other is a closed cooling system consisting of cooling towers and condensers.
Directory of Open Access Journals (Sweden)
Jun Du
2013-01-01
Full Text Available A scour monitoring system for subsea pipeline based on active thermometry is proposed in this paper. The temperature reading of the proposed system is based on a distributed Brillouin optical fiber sensing technique. A thermal cable acts as the main component of the system, which consists of a heating belt, armored optical fibers and heat-shrinkable tubes which run parallel to the pipeline. The scour-induced free span can be monitored through different heat transfer behaviors of in-water and in-sediment scenarios during heating and cooling processes. Two sets of experiments, including exposing different lengths of the upper surface of the pipeline to water and creating free spans of various lengths, were carried out in laboratory. In both cases, the scour condition was immediately detected by the proposed monitoring system, which confirmed the system is robust and very sensitive. Numerical study of the method was also investigated by using the finite element method (FEM with ANSYS, resulting in reasonable agreement with the test data. This brand new system provides a promising, low cost, highly precise and flexible approach for scour monitoring of subsea pipelines.
Numerical and classical analysis of V/STOL aircraft using selected propulsion systems
Wilson, S. B., III; Kidwell, G. H., Jr.; Christiansen, R. S.
1981-01-01
The development needed for the evolution of selected V/STOL research vehicles into optimized antisubmarine warfare (ASW) aircraft configurations, using numerical procedures and traditional analytical methods, has been examined. Three propulsion systems, which represent state-of-the-art development aimed at solving the thrust-vectoring and attitude-control problems of V/STOL aircraft, are analyzed. The use of NASA computer programs for aircraft synthesis (ACSYNT), and for optimizing configurations (COMMIN), coupled with contractor-supplied propulsion system data provides for accurate performance prediction of the selected ASW configurations. Particular emphasis on the transition phase between the research vehicle and the optimized configuration demonstrates the strengths and weaknesses of using generic research aircraft instead of building prototypes to demonstrate new technology
Numerical simulation of extraction behavior of major components in the CMPO-TBP-HNO3 system
International Nuclear Information System (INIS)
Takanashi, M.; Koma, Y.; Koyama, T.; Funasaka, H.
2000-01-01
A numerical simulation code was developed in order to find the optimum condition for separation and the recovery of TRU (TRansUranium) elements in the octyl(phenyl)-N,N-di-isobutyl-carbamoyl-methyl-phosphine oxide (CMPO) - tri-butyl phosphate (TBP) - HNO 3 solvent extraction system. This code is able to predict the extraction behavior of americium and europium in the system containing many components. Calculations of concentration profiles of americium and lanthanides were carried out for a counter current experiment with laboratory scale mixer-settlers. The calculated profiles were in agreement with the experimental ones. The effect of oxalic acid was also included in the calculation and was discussed. (authors)
Energy Technology Data Exchange (ETDEWEB)
Tornow, Sabine [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg, 86135 Augsburg (Germany); Tong, Ning-Hua [Institut fuer Theorie der Kondensierten Materie, Universitaet Karlsruhe, 76128 Karlsruhe (Germany); Bulla, Ralf [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg, 86135 Augsburg (Germany)
2006-07-05
We present a detailed model study of exciton transfer processes in donor-bridge-acceptor (DBA) systems. Using a model which includes the intermolecular Coulomb interaction and the coupling to a dissipative environment we calculate the phase diagram, the absorption spectrum as well as dynamic equilibrium properties with the numerical renormalization group. This method is non-perturbative and therefore allows one to cover the full parameter space, especially the case when the intermolecular Coulomb interaction is of the same order as the coupling to the environment and perturbation theory cannot be applied. For DBA systems with up to six sites we found a transition to the localized phase (self-trapping) depending on the coupling to the dissipative environment. We discuss various criteria which favour delocalized exciton transfer.
Tornow, Sabine; Tong, Ning-Hua; Bulla, Ralf
2006-07-05
We present a detailed model study of exciton transfer processes in donor-bridge-acceptor (DBA) systems. Using a model which includes the intermolecular Coulomb interaction and the coupling to a dissipative environment we calculate the phase diagram, the absorption spectrum as well as dynamic equilibrium properties with the numerical renormalization group. This method is non-perturbative and therefore allows one to cover the full parameter space, especially the case when the intermolecular Coulomb interaction is of the same order as the coupling to the environment and perturbation theory cannot be applied. For DBA systems with up to six sites we found a transition to the localized phase (self-trapping) depending on the coupling to the dissipative environment. We discuss various criteria which favour delocalized exciton transfer.
Harnessing type I and type III CRISPR-Cas systems for genome editing
DEFF Research Database (Denmark)
Li, Yingjun; Pan, Saifu; Zhang, Yan
2016-01-01
CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated) systems are widespread in archaea and bacteria, and research on their molecular mechanisms has led to the development of genome-editing techniques based on a few Type II systems. However, there has not been any...... report on harnessing a Type I or Type III system for genome editing. Here, a method was developed to repurpose both CRISPR-Cas systems for genetic manipulation in Sulfolobus islandicus, a thermophilic archaeon. A novel type of genome-editing plasmid (pGE) was constructed, carrying an artificial mini-CRISPR...... and selectively retained as transformants. Using this strategy, different types of mutation were generated, including deletion, insertion and point mutations. We envision this method is readily applicable to different bacteria and archaea that carry an active CRISPR-Cas system of DNA interference provided...
Numerical modeling assistance system in finite element analysis for the structure of an assembly
International Nuclear Information System (INIS)
Nakajima, Norihiro; Nishida, Akemi; Kawakami, Yoshiaki; Suzuki, Yoshio; Sawa, Kazuhiro; Iigaki, Kazuhiko
2015-01-01
The objective of structural analysis and seismic response analysis are well recognized and utilized as one of sophisticated analysis tools for design objects in the nuclear engineering. The way to design nuclear facilities is always in compromising with many index, such as costs, performance, robustness and so on, but the most important issues is the safety. It is true the structural analysis and seismic response analysis plays an important role to insure the safety, since it is well known that Japan is always facing to the earthquake. In this paper, a numerical analysis's controlling and managing system is implemented on a supercomputer, which controls the modelling process and data treating for structural robustness, although a numerical analysis's manager only controls a structural analysis by finite element method. The modeling process is described by the list of function ID and its procedures in a data base. The analytical modeling manager executes the process by order of the lists for simulation procedures. The manager controls the intention of an analysis by changing the analytical process one to another. Modeling process was experimentally found that may subject to the intention of designing index. The numerical experiments were carried out with static analyses and dynamic analyses. The results of its experiment introduce reasonable discussion to understand the accuracy of simulation. In the numerical experiments, K, supercomputer is utilized by using parallel computing resource with the controlling and managing system. The structural analysis and seismic response analysis are done by the FIEST, finite element analysis for the structure of an assembly, which carries out the simulation by gathering components. As components are attached to one another to build an assembly, and, therefore, the interactions between the components due to differences in material properties and their connection conditions considerably affect the behavior of an assembly. FIESTA is
Ownens, Albert K.; Lavelle, Thomas M.; Hervol, David S.
2010-01-01
A Dual Brayton Power Conversion System (DBPCS) has been tested at the NASA Glenn Research Center using Nitrogen (N2) as the working fluid. This system uses two closed Brayton cycle systems that share a common heat source and working fluid but are otherwise independent. This system has been modeled using the Numerical Propulsion System Simulation (NPSS) environment. This paper presents the results of a numerical study that investigated system performance changes resulting when the working fluid is changed from gaseous (N2) to gaseous carbon dioxide (CO2).
Position Ring System using Anger Type Detectors
Energy Technology Data Exchange (ETDEWEB)
Joel S. Karp, principal investigator
2004-12-14
The overall objective of our project was to develop PET scanners and imaging techniques that achieve high performance and excellent image quality. Our approach was based upon 3-D imaging (no septa) with position-sensitive Anger-logic detectors, whereby the encoding ratio of resolution elements to number of photo-multiplier tube channels is very high. This design led to a series of PET systems that emphasized cost-effectiveness and practicality in a clinical environment.
Kettle, L. M.; Mora, P.; Weatherley, D.; Gross, L.; Xing, H.
2006-12-01
Simulations using the Finite Element method are widely used in many engineering applications and for the solution of partial differential equations (PDEs). Computational models based on the solution of PDEs play a key role in earth systems simulations. We present numerical modelling of crustal fault systems where the dynamic elastic wave equation is solved using the Finite Element method. This is achieved using a high level computational modelling language, escript, available as open source software from ACcESS (Australian Computational Earth Systems Simulator), the University of Queensland. Escript is an advanced geophysical simulation software package developed at ACcESS which includes parallel equation solvers, data visualisation and data analysis software. The escript library was implemented to develop a flexible Finite Element model which reliably simulates the mechanism of faulting and the physics of earthquakes. Both 2D and 3D elastodynamic models are being developed to study the dynamics of crustal fault systems. Our final goal is to build a flexible model which can be applied to any fault system with user-defined geometry and input parameters. To study the physics of earthquake processes, two different time scales must be modelled, firstly the quasi-static loading phase which gradually increases stress in the system (~100years), and secondly the dynamic rupture process which rapidly redistributes stress in the system (~100secs). We will discuss the solution of the time-dependent elastic wave equation for an arbitrary fault system using escript. This involves prescribing the correct initial stress distribution in the system to simulate the quasi-static loading of faults to failure; determining a suitable frictional constitutive law which accurately reproduces the dynamics of the stick/slip instability at the faults; and using a robust time integration scheme. These dynamic models generate data and information that can be used for earthquake forecasting.
Liu, Yao; Liu, Baoliang; Lei, Jilin; Guan, Changtao; Huang, Bin
2017-07-01
A three-dimensional numerical model was established to simulate the hydrodynamics within an octagonal tank of a recirculating aquaculture system. The realizable k- ɛ turbulence model was applied to describe the flow, the discrete phase model (DPM) was applied to generate particle trajectories, and the governing equations are solved using the finite volume method. To validate this model, the numerical results were compared with data obtained from a full-scale physical model. The results show that: (1) the realizable k- ɛ model applied for turbulence modeling describes well the flow pattern in octagonal tanks, giving an average relative error of velocities between simulated and measured values of 18% from contour maps of velocity magnitudes; (2) the DPM was applied to obtain particle trajectories and to simulate the rate of particle removal from the tank. The average relative error of the removal rates between simulated and measured values was 11%. The DPM can be used to assess the self-cleaning capability of an octagonal tank; (3) a comprehensive account of the hydrodynamics within an octagonal tank can be assessed from simulations. The velocity distribution was uniform with an average velocity of 15 cm/s; the velocity reached 0.8 m/s near the inlet pipe, which can result in energy losses and cause wall abrasion; the velocity in tank corners was more than 15 cm/s, which suggests good water mixing, and there was no particle sedimentation. The percentage of particle removal for octagonal tanks was 90% with the exception of a little accumulation of ≤ 5 mm particle in the area between the inlet pipe and the wall. This study demonstrated a consistent numerical model of the hydrodynamics within octagonal tanks that can be further used in their design and optimization as well as promote the wide use of computational fluid dynamics in aquaculture engineering.
International Nuclear Information System (INIS)
Crisanti, A; Ritort, F
2003-01-01
This review reports on the research done during past years on violations of the fluctuation-dissipation theorem (FDT) in glassy systems. It is focused on the existence of a quasi-fluctuation-dissipation theorem (QFDT) in glassy systems and the current supporting knowledge gained from numerical simulation studies. It covers a broad range of non-stationary aging and stationary driven systems such as structural glasses, spin glasses, coarsening systems, ferromagnetic models at criticality, trap models, models with entropy barriers, kinetically constrained models, sheared systems and granular media. The review is divided into four main parts: (1) an introductory section explaining basic notions related to the existence of the FDT in equilibrium and its possible extension to the glassy regime (QFDT), (2) a description of the basic analytical tools and results derived in the framework of some exactly solvable models, (3) a detailed report of the current evidence in favour of the QFDT and (4) a brief digression on the experimental evidence in its favour. This review is intended for inexpert readers who want to learn about the basic notions and concepts related to the existence of the QFDT as well as for the more expert readers who may be interested in more specific results. (topical review)
Surgical clothing systems in laminar airflow operating room: a numerical assessment.
Sadrizadeh, Sasan; Holmberg, Sture
2014-01-01
This study compared two different laminar airflow distribution strategies - horizontal and vertical - and investigated the effectiveness of both ventilation systems in terms of reducing the sedimentation and distribution of bacteria-carrying particles. Three different staff clothing systems, which resulted in source strengths of 1.5, 4 and 5 CFU/s per person, were considered. The exploration was conducted numerically using a computational fluid dynamics technique. Active and passive air sampling methods were simulated in addition to recovery tests, and the results were compared. Model validation was performed through comparisons with measurement data from the published literature. The recovery test yielded a value of 8.1 min for the horizontal ventilation scenario and 11.9 min for the vertical ventilation system. Fewer particles were captured by the slit sampler and in sedimentation areas with the horizontal ventilation system. The simulated results revealed that under identical conditions in the examined operating room, the horizontal laminar ventilation system performed better than the vertical option. The internal constellation of lamps, the surgical team and objects could have a serious effect on the movement of infectious particles and therefore on postoperative surgical site infections. Copyright © 2014 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.
Power control system in BWR type reactors
International Nuclear Information System (INIS)
Nishizawa, Yasuo.
1980-01-01
Purpose: To control the reactor power so that the power distribution can satisfy the limiting conditions, by regulating the reactor core flow rate while monitoring the power distribution in the reactor core of a BWR type reactor. Constitution: A power distribution monitor determines the power distribution for the entire reactor core based on the data for neutron flux, reactor core thermal power, reactor core flow rate and control rod pattern from the reactor and calculates the linear power density distribution. A power up ratio computing device computes the current linear power density increase ratio. An aimed power up ratio is determined by converting the electrical power up ratio transferred from a load demand input device into the reactor core thermal power up ratio. The present reactor core thermal power up ratio is subtracted from the limiting power up ratio and the difference is sent to an operation amount indicator and the reactor core flow rate is changed in a reactor core flow rate regulator, by which the reactor power is controlled. (Moriyama, K.)
Feedwater control system in BWR type reactor
International Nuclear Information System (INIS)
Tanji, Jun-ichi; Oomori, Takashi.
1980-01-01
Purpose: To improve the water level control performance in BWR type reactor by regulating the water level set to the reactor depending on the rate of change in the recycling amount of coolant to thereby control the fluctuations in the water level resulted in the reactor within an aimed range even upon significant fluctuations in the recycling flow rate. Constitution: The recycling flow rate of coolant in the reactor is detected and the rate of its change with time is computed to form a rate of change signal. The rate of change signal is inputted to a reactor level setter to amend the actual reactor water level demand signal and regulate the water level set to the reactor water depending on the rate of change in the recycling flow rate. Such a regulation method for the set water level enables to control the water level fluctuation resulted in the reactor within the aimed range even upon the significant fluctuation in the recycling flow rate and improve the water level control performance of the reactor, whereby the operationability for the reactor is improved to enhance the operation rate. (Moriyama, K.)
Numerical Investigations into the Value of Information in Lifecycle Analysis of Structural Systems
DEFF Research Database (Denmark)
Konakli, Katerina; Sudret, Bruno; Faber, Michael Havbro
2015-01-01
of decisions related to maintenance of structural systems. In this context, experiments may refer to inspections or structural health monitoring. The value-of-information concept comprises a powerful tool for determining whether the experimental cost is justified by the expected gained benefit during...... investigations demonstrate how the decision problem is influenced by the assumed probabilistic models, including the type of probability distribution and the degree of uncertainty reflected in the coefficient of variation, the degradation law, the quantity and quality of information, and the probabilistic...... dependencies between the components of a system. Furthermore, challenges and potentials in value-of-information analysis for structural systems are discussed....
Type systems for distributed programs components and sessions
Dardha, Ornela
2016-01-01
In this book we develop powerful techniques based on formal methods for the verification of correctness, consistency and safety properties related to dynamic reconfiguration and communication in complex distributed systems. In particular, static analysis techniques based on types and type systems are an adequate methodology considering their success in guaranteeing not only basic safety properties, but also more sophisticated ones like deadlock or lock freedom in concurrent settings. The main contributions of this book are twofold. i) We design a type system for a concurrent object-oriented calculus to statically ensure consistency of dynamic reconfigurations. ii) We define an encoding of the session pi-calculus, which models communication in distributed systems, into the standard typed pi-calculus. We use this encoding to derive properties like type safety and progress in the session pi-calculus by exploiting the corresponding properties in the standard typed pi-calculus.
Primary cooling system for BWR type reactor
International Nuclear Information System (INIS)
Ibe, Eishi; Takahashi, Masanori; Aoki, Yasuko
1993-01-01
The present invention effectively uses information from a plurality of sensors in order to suppress corrosion circumstance of a nuclear reactor. That is, a predetermined general water quality factor at a predetermined position is determined as a standard index. A concentration of a water quality improver is controlled such that the index is within an aimed range. For this purpose, the entire sensor groups disposed in a primary coolant system of a nuclear reactor are divided into a plural systems of sensor groups each disposed on every different positions. Then, a predetermined sensor group (standard sensor group) is connected to a computing device and a data base so that it is always monitored for calculating and estimating the standard index. Only oxidative ingredient in water at the measuring point is noted, and a concentration distribution which agrees with an actually measured value of oxidative ingredients is extracted from data base and used as a correct concentration distribution. With such procedures, reactor water quality can be estimated accurately while compensating erroneous factors of individual sensors. Even when a new sensor is used, it is not necessary to greatly change control logic. (I.S.)
Experimental and Numerical Research Activity on a Packed Bed TES System
Directory of Open Access Journals (Sweden)
Mario Cascetta
2016-09-01
Full Text Available This paper presents the results of experimental and numerical research activities on a packed bed sensible thermal energy storage (TES system. The TES consists of a cylindrical steel tank filled with small alumina beads and crossed by air used as the heat transfer fluid. Experimental tests were carried out while varying some operating parameters such as the mass flow rate, the inlet–outlet temperature thresholds and the aspect ratio (length over diameter. Numerical simulations were carried out using a one-dimensional model, specifically developed in the Matlab-Simulink environment and a 2D axisymmetric model based on the ANSYS-Fluent platform. Both models are based on a two-equation transient approach to calculate fluid and solid phase temperatures. Thermodynamic properties were considered to be temperature-dependent and, in the Computational Fluid Dynamics (CFD model, variable porosity of the bed in the radial direction, thermal losses and the effective conductivity of the alumina beads were also considered. The simulation results of both models were compared to the experimental ones, showing good agreement. The one-dimensional model has the advantage of predicting the axial temperature distribution with a very low computational cost, but it does not allow calculation of the correct energy stored when the temperature distribution is strongly influenced by the wall. To overcome this problem a 2D CFD model was used in this work.
Applications of magnetohydrodynamics in biological systems-a review on the numerical studies
Rashidi, Saman; Esfahani, Javad Abolfazli; Maskaniyan, Mahla
2017-10-01
Magnetohydrodynamic (MHD) fluid flow in different geometries relevant to human body parts is an interesting and important scientific area due to its applications in medical sciences. This article performs a comprehensive review on the applications of MHD and their numerical modelling in biological systems. Applications of MHD in medical sciences are classified into four categories in this paper. Applications of MHD in simple flow, peristaltic flow, pulsatile flow, and drag delivery are these categories. The numerical researches performed for these categories are reviewed and summarized separately. Finally, some conclusions and suggestions for future works based on the literature review are presented. The results indicated that during a surgery when it is necessary to drop blood flow or reduce tissue temperature, it may be achieved by using a magnetic field. Moreover, the review showed that the trapping is an important phenomenon in peristaltic flows that causes the formation of thrombus in blood and the movement of food bolus in gastrointestinal tract. This phenomenon may be disappeared by using a proper magnetic field. Finally, the concentration of particles that are delivered to the target region increases with an increase in the magnetic field intensity.
Numerical Analysis of CNC Milling Chatter Using Embedded Miniature MEMS Microphone Array System
Directory of Open Access Journals (Sweden)
Pang-Li Wang
2018-01-01
Full Text Available With the increasingly common use of industrial automation for mass production, there are many computer numerical control (CNC machine tools that require the collection of data from intelligent sensors in order to analyze their processing quality. In general, for high speed rotating machines, an accelerometer can be attached on the spindle to collect the data from the detected vibration of the CNC. However, due to their cost, accelerometers have not been widely adopted for use with typical CNC machine tools. This study sought to develop an embedded miniature MEMS microphone array system (Radius 5.25 cm, 8 channels to discover the vibration source of the CNC from spatial phase array processing. The proposed method utilizes voice activity detection (VAD to distinguish between the presence and absence of abnormal noise in the pre-stage, and utilizes the traditional direction of arrival method (DOA via multiple signal classification (MUSIC to isolate the spatial orientation of the noise source in post-processing. In the numerical simulation, the non-interfering noise source location is calibrated in the anechoic chamber, and is tested with real milling processing in the milling machine. As this results in a high background noise level, the vibration sound source is more accurate in the presented energy gradation graphs as compared to the traditional MUSIC method.
Numerical Study on Different Series Modes of Jet Fan in a Longitudinal Tunnel Ventilation System
Directory of Open Access Journals (Sweden)
Guihong Pei
2014-01-01
Full Text Available Efficient ventilation systems will contribute to maintaining air quality in the tunnel. In order to improve ventilation performance in normal traffic condition, the 3D tunnel models were established according to the original design for the tunnel located in central plains of China. Based on the commercial CFD software Fluent 6.3 and k-ε turbulence model, numerical simulations were carried out to study the patterns of jet flow and the optimization of fan combinations. It is found that the axial velocity profile obtained from numerical simulation agrees quite well with turbulent free jet theory although there is a little difference on the magnitude. The comparison of four combination modes under the condition of operating four fans indicates that the ventilation effectiveness is affected mainly by both the interval of adjacent groups of fans and the combination modes of operational fans. According to the simulation results, a novel combination mode which consists of a group double paralleled fans and two groups single fan is designed. The novel combination mode is regarded as the optimum combination mode with respect to maximizing air velocity in the tunnel. Compared to the traditional combination modes, it will increase the air velocity by 5.7%.
Numerical study for determining PF coil system parameters in MHD equilibrium of KT-2 tokamak plasma
International Nuclear Information System (INIS)
Ryu, J.; Hong, S.H.; Lee, K.W.; Hong, B.G.; In, S.R.; Kim, S.K.
1995-01-01
The KT-2 is a large-aspect-ratio medium-sized divertor tokamak in the conceptual design phase and planned to be operational in 1998 at the Korea Atomic Energy Research Institute (KAERI). Plasma equilibrium in tokamak can be acquired by controlling the current of poloidal field (PF) coils in appropriate geometries and positions. In this study, the authors have performed numerical calculations to achieve the various equilibrium conditions fitting given plasma shapes and satisfying PF current limitations. Usually an ideal magnetohydrodynamic (MHD) equation is used to obtain the equilibrium solution of tokamak plasma, and it is practical to take advantage of a numerical method in solving the MHD equation because it has nonlinear source terms. Two equilibrium codes have been applied to find a double-null configuration of free-boundary tokamak plasma in KT-2: one is of the authors' own developing and the other is a free-boundary tokamak equilibrium code (FBT) that has been used mainly for the verification of developed code's results. PF coil system parameters including their positions and currents are determined for the optimization of input power required when the specifications of KT-2 tokamak are met. Then, several sets of equilibrium conditions during the tokamak operation are found to observe the changes of poloidal field currents with the passing of operation time step, and the basic stability problems related with the magnetic field structure is also considered
Friedrich, R.; Drewelow, W.
1978-01-01
An algorithm is described that is based on the method of breaking the Laplace transform down into partial fractions which are then inverse-transformed separately. The sum of the resulting partial functions is the wanted time function. Any problems caused by equation system forms are largely limited by appropriate normalization using an auxiliary parameter. The practical limits of program application are reached when the degree of the denominator of the Laplace transform is seven to eight.
Numerical prediction of flow and mixing characteristics in CVCS chemical addition system
International Nuclear Information System (INIS)
Chang, K.S.
1999-01-01
A numerical result of the flow and mixing characteristics is presented for the flow field created by water injected into a cylindrical tank with an initially stationary fluid. The flow is relevant to the operation of the chemical addition system in the chemical and volume control system (CVCS) of nuclear power plants. This study was undertaken to provide a basis for modification of the previous design which gave a number of difficulties in installation and operation of the chemical addition system because it needs a special reciprocating pump with a high actual head. For the tank of length-to-diameter ratios (L/D) of 1, 2 and 3, each with and without a baffle inside, calculation results were obtained by solving the unsteady laminar two-dimensional elliptic forms of governing equations for the mass, momentum and species concentration. Finite-difference method was used to obtain discretization equations, and the SIMPLER solution algorithm was employed for the calculation procedure. Results showed that the baffle was very effective in enhancing the mixing in the tank, and that a baffle should be installed near the tank entrance in order to inject chemicals into the reactor coolant system (RCS) within the operating time required. (orig.)
Directory of Open Access Journals (Sweden)
A. Sambas
2013-09-01
Full Text Available Chaotic systems are characterized by sensitive dependence on initial conditions, similar to random behavior, and continuous broad-band power spectrum. Chaos is a good potential to be used in secure communications system. In this paper, in order to show some interesting phenomena of three-order Jerk circuit with modulus nonlinearity, the chaotic behavior as a function of a variable control parameter, has been studied. The initial study in this paper is to analyze the phase portraits, the Poincaré maps, the bifurcation diagrams, while the analysis of the synchronization in the case of unidirectional coupling between two identical generated chaotic systems, has been presented. Moreover, some appropriate comparisons are made to contrast some of the existing results. Finally, the effectiveness of the unidirectional coupling scheme between two identical Jerk circuits in a secure communication system is presented in details. Integration of theoretical physics, the numerical simulation by using MATLAB 2010, as well as the implementation of circuit simulations by using MultiSIM 10.0 has been performed in this study
International Nuclear Information System (INIS)
Elnaggar, M.; Abdel Fattah, H.A.; Elshafei, A.L.
2014-01-01
This paper presents a complete design of a two-level control system to capture maximum power in wind energy conversion systems. The upper level of the proposed control system adopts a modified line search optimization algorithm to determine a setpoint for the wind turbine speed. The calculated speed setpoint corresponds to the maximum power point at given operating conditions. The speed setpoint is fed to a generalized predictive controller at the lower level of the control system. A different formulation, that treats the aerodynamic torque as a disturbance, is postulated to derive the control law. The objective is to accurately track the setpoint while keeping the control action free from unacceptably fast or frequent variations. Simulation results based on a realistic model of a 1.5 MW wind turbine confirm the superiority of the proposed control scheme to the conventional ones. - Highlights: • The structure of a MPPT (maximum power point tracking) scheme is presented. • The scheme is divided into the optimization algorithm and the tracking controller. • The optimization algorithm is based on an online line search numerical algorithm. • The tracking controller is treating the aerodynamics torque as a loop disturbance. • The control technique is simulated with stochastic wind speed by Simulink and FAST
International Nuclear Information System (INIS)
Ommen, Torben; Elmegaard, Brian
2012-01-01
Highlights: ► A transcritical booster refrigeration plant is modelled. ► We examine changes in cost flow at different operation parameters. ► The use of characteristic curves for diagnosis is studied. - Abstract: Transcritical/subcritical booster refrigeration systems are increasingly installed and used in Danish supermarkets. The systems operate in both transcritical and subcritical conditions dependent on the heat rejection performance and the ambient conditions. The plant consists of one refrigerant cycle supplying refrigerant for evaporators in both chilled and frozen display cases. In the paper, thermoeconomic theory is used to establish the cost of cooling at each individual temperature level based on operating costs. With a high amount of operating systems, faulty operation becomes an economic, and environmental, interest. A general solution for evaluation of these systems is considered, with the objective to reduce cost and power consumption of malfunctioning equipment in operation. An analysis of the use of thermoeconomic diagnosis methods is required, as these methods may prove applicable. To accommodate the analysis, a numerical model of a transcritical booster refrigeration plant is considered in this paper. Additionally the characteristic curves method is applied to the high pressure compressor unit of the refrigeration plant. The approach successfully determine whether an anomaly is intrinsic or induced in the component when no uncertainties are introduced in the steady state model.
Type I interferon signature in systemic lupus erythematosus.
Bezalel, Shira; Guri, Keren Mahlab; Elbirt, Daniel; Asher, Ilan; Sthoeger, Zev Moshe
2014-04-01
Type I interferons (IFN) are primarily regarded as an inhibitor of viral replication. However, type I IFN, mainly IFNalpha, plays a major role in activation of both the innate and adaptive immune systems. Systemic lupus erythematosus (SLE) is a chronic, multi-systemic, inflammatory autoimmune disease with undefined etiology. SLE is characterized by dysregulation of both the innate and the adaptive immune systems. An increased expression of type I IFN-regulated genes, termed IFN signature, has been reported in patients with SLE. We review here the role of IFNalpha in the pathogenesis and course of SLE and the possible role of IFNalpha inhibition as a novel treatment for lupus patients.
Numerical Investigation of Multiple-, Interacting-Scale Variable-Density Ground Water Flow Systems
Cosler, D.; Ibaraki, M.
2004-12-01
The goal of our study is to elucidate the nonlinear processes that are important for multiple-, interacting-scale flow and solute transport in subsurface environments. In particular, we are focusing on the influence of small-scale instability development on variable-density ground water flow behavior in large-scale systems. Convective mixing caused by these instabilities may mix the fluids to a greater extent than would be the case with classical, Fickian dispersion. Most current numerical schemes for interpreting field-scale variable-density flow systems do not explicitly account for the complexities caused by small-scale instabilities and treat such processes as "lumped" Fickian dispersive mixing. Such approaches may greatly underestimate the mixing behavior and misrepresent the overall large-scale flow field dynamics. The specific objectives of our study are: (i) to develop an adaptive (spatial and temporal scales) three-dimensional numerical model that is fully capable of simulating field-scale variable-density flow systems with fine resolution (~1 cm); and (ii) to evaluate the importance of scale-dependent process interactions by performing a series of simulations on different problem scales ranging from laboratory experiments to field settings, including an aquifer storage and freshwater recovery (ASR) system similar to those planned for the Florida Everglades and in-situ contaminant remediation systems. We are examining (1) methods to create instabilities in field-scale systems, (2) porous media heterogeneity effects, and (3) the relation between heterogeneity characteristics (e.g., permeability variance and correlation length scales) and the mixing scales that develop for varying degrees of unstable stratification. Applications of our work include the design of new water supply and conservation measures (e.g., ASR systems), assessment of saltwater intrusion problems in coastal aquifers, and the design of in-situ remediation systems for aquifer restoration
ANALYSIS OF EXISTING AND PROSPECTIVE TECHNICAL CONTROL SYSTEMS OF NUMERIC CODES AUTOMATIC BLOCKING
Directory of Open Access Journals (Sweden)
A. M. Beznarytnyy
2013-09-01
Full Text Available Purpose. To identify the characteristic features of the engineering control measures system of automatic block of numeric code, identifying their advantages and disadvantages, to analyze the possibility of their use in the problems of diagnosing status of the devices automatic block and setting targets for the development of new diagnostic systems. Methodology. In order to achieve targets the objective theoretical and analytical method and the method of functional analysis have been used. Findings. The analysis of existing and future facilities of the remote control and diagnostics automatic block devices had shown that the existing systems of diagnosis were not sufficiently informative, designed primarily to control the discrete parameters, which in turn did not allow them to construct a decision support subsystem. In developing of new systems of technical diagnostics it was proposed to use the principle of centralized distributed processing of diagnostic data, to include a subsystem support decision-making in to the diagnostics system, it will reduce the amount of work to maintain the devices blocking and reduce recovery time after the occurrence injury. Originality. As a result, the currently existing engineering controls facilities of automatic block can not provide a full assessment of the state distillation alarms and locks. Criteria for the development of new systems of technical diagnostics with increasing amounts of diagnostic information and its automatic analysis were proposed. Practical value. These results of the analysis can be used in practice in order to select the technical control of automatic block devices, as well as the further development of diagnostic systems automatic block that allows for a gradual transition from a planned preventive maintenance service model to the actual state of the monitored devices.
Extending Dylan's type system for better type inference and error detection
DEFF Research Database (Denmark)
Mehnert, Hannes
2010-01-01
a dynamically typed language. Dylan poses several special challenges for gradual typing, such as multiple return values, variable-arity methods and generic functions (multiple dispatch). In this paper Dylan is extended with function types and parametric polymorphism. We implemented the type system...... and aunification-based type inference algorithm in the mainstream Dylan compiler. As case study we use the Dylan standard library (roughly 32000 lines of code), which witnesses that the implementation generates faster code with fewer errors. Some previously undiscovered errors in the Dylan library were revealed....
Core monitoring system for FBR type reactor
International Nuclear Information System (INIS)
Azekura, Kazuo.
1981-01-01
Purpose: To determine power distribution ON-line after the change of the insertion degree of control rods by the provision of means for calculating power change coefficient at each of the points due to the change in the insertion degree from the specific change of insertion degree and multiplying the same with the newest power distribution determined periodically by the diffusion calculation. Constitution: The monitoring system additionally comprises a calculation device for power change coefficient that calculates the power change coefficient in a fuel assembly adjacent to a control rod based on the data concerning the operation of the control rod, and a provisional power distribution calculation device that executes multiplication between the power distribution calculated in a periodical power distribution calculation device based on the calculation instruction and stored in the core and the power change coefficient from the power change coefficient calculation device and forecasts the provisional power distribution. Then, based on the result of the foregoing calculations, 2-dimensional power distribution, maximum temperature for the cladding tube of the specified fuel assembly, maximum temperature of pellets in the specified fuel assembly, maximum power density and the like are calculated in various display value calculation devices and displayed on a display device. (Horiuchi, T.)
The dynamical complexity of a Ivlev-type prey-predator system with impulsive effect
International Nuclear Information System (INIS)
Wang Hailing; Wang Weiming
2008-01-01
Based on the classical predator-prey system with Ivlev-type functional response, an impulsive differential equations to model the process of periodic perturbations on the predator at different fixed time is established. It proves that there exists a locally asymptotically stable prey-eradication periodic solution when the impulse period is less than some critical value, and otherwise, the system can be permanent. Numerical results show that the system considered has more complicated dynamics. such as quasi-periodic oscillation, narrow periodic window, wide periodic window, chaotic bands, symmetry-breaking pitchfork bifurcation and crises, etc
Numerical Estimation of Balanced and Falling States for Constrained Legged Systems
Mummolo, Carlotta; Mangialardi, Luigi; Kim, Joo H.
2017-08-01
Instability and risk of fall during standing and walking are common challenges for biped robots. While existing criteria from state-space dynamical systems approach or ground reference points are useful in some applications, complete system models and constraints have not been taken into account for prediction and indication of fall for general legged robots. In this study, a general numerical framework that estimates the balanced and falling states of legged systems is introduced. The overall approach is based on the integration of joint-space and Cartesian-space dynamics of a legged system model. The full-body constrained joint-space dynamics includes the contact forces and moments term due to current foot (or feet) support and another term due to altered contact configuration. According to the refined notions of balanced, falling, and fallen, the system parameters, physical constraints, and initial/final/boundary conditions for balancing are incorporated into constrained nonlinear optimization problems to solve for the velocity extrema (representing the maximum perturbation allowed to maintain balance without changing contacts) in the Cartesian space at each center-of-mass (COM) position within its workspace. The iterative algorithm constructs the stability boundary as a COM state-space partition between balanced and falling states. Inclusion in the resulting six-dimensional manifold is a necessary condition for a state of the given system to be balanced under the given contact configuration, while exclusion is a sufficient condition for falling. The framework is used to analyze the balance stability of example systems with various degrees of complexities. The manifold for a 1-degree-of-freedom (DOF) legged system is consistent with the experimental and simulation results in the existing studies for specific controller designs. The results for a 2-DOF system demonstrate the dependency of the COM state-space partition upon joint-space configuration (elbow-up vs
Automated aberration correction of arbitrary laser modes in high numerical aperture systems.
Hering, Julian; Waller, Erik H; Von Freymann, Georg
2016-12-12
Controlling the point-spread-function in three-dimensional laser lithography is crucial for fabricating structures with highest definition and resolution. In contrast to microscopy, aberrations have to be physically corrected prior to writing, to create well defined doughnut modes, bottlebeams or multi foci modes. We report on a modified Gerchberg-Saxton algorithm for spatial-light-modulator based automated aberration compensation to optimize arbitrary laser-modes in a high numerical aperture system. Using circularly polarized light for the measurement and first-guess initial conditions for amplitude and phase of the pupil function our scalar approach outperforms recent algorithms with vectorial corrections. Besides laser lithography also applications like optical tweezers and microscopy might benefit from the method presented.
Numerical simulation of flow field in cooling tower of passive residual heat removal system of HTGR
International Nuclear Information System (INIS)
Li Xiaowei; Zhang Li; Wu Xinxin; He Shuyan
2011-01-01
Environmental wind will influence the working conditions of natural convection cooling tower. The velocity and temperature fields in the natural convection cooling tower of the HTGR residual heat removal system at different environmental wind velocities were numerically simulated. The results show that, if there is no wind baffle, the flow in the cooling tower is blocked when environmental wind velocity is higher than 6 m/s, residual heat can hardly be removed, and when wind velocity is higher than 9 m/s, the air even flow downwards in the tower, so wind baffle is very necessary. With the wind baffle installed, the cooling tower works well at the wind speed even higher than 9 m/s. The optimum baffle size and positions are also analyzed. (authors)
Numerical methods for reliability and safety assessment multiscale and multiphysics systems
Hami, Abdelkhalak
2015-01-01
This book offers unique insight on structural safety and reliability by combining computational methods that address multiphysics problems, involving multiple equations describing different physical phenomena, and multiscale problems, involving discrete sub-problems that together describe important aspects of a system at multiple scales. The book examines a range of engineering domains and problems using dynamic analysis, nonlinear methods, error estimation, finite element analysis, and other computational techniques. This book also: · Introduces novel numerical methods · Illustrates new practical applications · Examines recent engineering applications · Presents up-to-date theoretical results · Offers perspective relevant to a wide audience, including teaching faculty/graduate students, researchers, and practicing engineers
International Nuclear Information System (INIS)
Takagi, T.; Miki, K.; Chen, B.C.J.; Sha, W.T.
1985-01-01
A new method is presented for numerically generating boundary-fitted coordinate systems for arbitrarily curved surfaces. The three-dimensional surface has been expressed by functions of two parameters using the geometrical modeling techniques in computer graphics. This leads to new quasi-one- and two-dimensional elliptic partial differential equations for coordinate transformation. Since the equations involve the derivatives of the surface expressions, the grids geneated by the equations distribute on the surface depending on its slope and curvature. A computer program GRID-CS based on the method was developed and applied to a surface of the second order, a torus and a surface of a primary containment vessel for a nuclear reactor. These applications confirm that GRID-CS is a convenient and efficient tool for grid generation on arbitrarily curved surfaces
International Nuclear Information System (INIS)
Wolff, Marc
2011-01-01
This work is devoted to the construction of numerical methods that allow the accurate simulation of inertial confinement fusion (ICF) implosion processes by taking self-generated magnetic field terms into account. In the sequel, we first derive a two-temperature resistive magnetohydrodynamics model and describe the considered closure relations. The resulting system of equations is then split in several subsystems according to the nature of the underlying mathematical operator. Adequate numerical methods are then proposed for each of these subsystems. Particular attention is paid to the development of finite volume schemes for the hyperbolic operator which actually is the hydrodynamics or ideal magnetohydrodynamics system depending on whether magnetic fields are considered or not. More precisely, a new class of high-order accurate dimensionally split schemes for structured meshes is proposed using the Lagrange re-map formalism. One of these schemes' most innovative features is that they have been designed in order to take advantage of modern massively parallel computer architectures. This property can for example be illustrated by the dimensionally split approach or the use of artificial viscosity techniques and is practically highlighted by sequential performance and parallel efficiency figures. Hyperbolic schemes are then combined with finite volume methods for dealing with the thermal and resistive conduction operators and taking magnetic field generation into account. In order to study the characteristics and effects of self-generated magnetic field terms, simulation results are finally proposed with the complete two-temperature resistive magnetohydrodynamics model on a test problem that represents the state of an ICF capsule at the beginning of the deceleration phase. (author)
3D printing application and numerical simulations in a fracture system
Yoon, H.; Martinez, M. J.
2017-12-01
The hydrogeological and mechanical properties in fractured and porous media are fundamental to predicting coupled multiphysics processes in the subsurface. Recent advances in experimental methods and multi-scale imaging capabilities have revolutionized our ability to quantitatively characterize geomaterials and digital counterparts are now routinely used for numerical simulations to characterize petrophysical and mechanical properties across scales. 3D printing is a very effective and creative technique that reproduce the digital images in a controlled way. For geoscience applications, 3D printing can be co-opted to print reproducible porous and fractured structures derived from CT-imaging of actual rocks and theoretical algorithms for experimental testing. In this work we used a stereolithography (SLA) method to create a single fracture network. The fracture in shale was first scanned using a microCT system and then the digital fracture network was printed into two parts and assembled. Aperture ranges from 0.3 to 1 mm. In particular, we discuss the design of single fracture network and the progress of printing practices to reproduce the fracture network system. Printed samples at different scales are used to measure the permeability and surface roughness. Various numerical simulations including (non-)reactive transport and multiphase flow cases are performed to study fluid flow characterization. We will also discuss the innovative advancement of 3D printing techniques applicable for coupled processes in the subsurface. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.
Chin, Jeffrey C.; Csank, Jeffrey T.; Haller, William J.; Seidel, Jonathan A.
2016-01-01
This document outlines methodologies designed to improve the interface between the Numerical Propulsion System Simulation framework and various control and dynamic analyses developed in the Matlab and Simulink environment. Although NPSS is most commonly used for steady-state modeling, this paper is intended to supplement the relatively sparse documentation on it's transient analysis functionality. Matlab has become an extremely popular engineering environment, and better methodologies are necessary to develop tools that leverage the benefits of these disparate frameworks. Transient analysis is not a new feature of the Numerical Propulsion System Simulation (NPSS), but transient considerations are becoming more pertinent as multidisciplinary trade-offs begin to play a larger role in advanced engine designs. This paper serves to supplement the relatively sparse documentation on transient modeling and cover the budding convergence between NPSS and Matlab based modeling toolsets. The following sections explore various design patterns to rapidly develop transient models. Each approach starts with a base model built with NPSS, and assumes the reader already has a basic understanding of how to construct a steady-state model. The second half of the paper focuses on further enhancements required to subsequently interface NPSS with Matlab codes. The first method being the simplest and most straightforward but performance constrained, and the last being the most abstract. These methods aren't mutually exclusive and the specific implementation details could vary greatly based on the designer's discretion. Basic recommendations are provided to organize model logic in a format most easily amenable to integration with existing Matlab control toolsets.
Elkhoury, J. E.; Detwiler, R. L.; Serajian, V.; Bruno, M. S.
2012-12-01
Geothermal energy resources are more widespread than previously thought and have the potential for providing a significant amount of sustainable clean energy worldwide. In particular, hot permeable sedimentary formations provide many advantages over traditional geothermal recovery and enhanced geothermal systems in low permeability crystalline formations. These include: (1) eliminating the need for hydraulic fracturing, (2) significant reduction in risk for induced seismicity, (3) reducing the need for surface wastewater disposal, (4) contributing to decreases in greenhouse gases, and (5) potential use for CO2 sequestration. Advances in horizontal drilling, completion, and production technology from the oil and gas industry can now be applied to unlock these geothermal resources. Here, we present experimental results from a laboratory scale circulation system and numerical simulations aimed at quantifying the heat transfer capacity of sedimentary rocks. Our experiments consist of fluid flow through a saturated and pressurized sedimentary disc of 23-cm diameter and 3.8-cm thickness heated along its circumference at a constant temperature. Injection and production ports are 7.6-cm apart in the center of the disc. We used DI de-aired water and mineral oil as working fluids and explored temperatures from 20 to 150 oC and flow rates from 2 to 30 ml/min. We performed experiments on sandstone samples (Castlegate and Kirby) with different porosity, permeability and thermal conductivity to evaluate the effect of hydraulic and thermal properties on the heat transfer capacity of sediments. The producing fluid temperature followed an exponential form with time scale transients between 15 and 45 min. Steady state outflow temperatures varied between 60% and 95% of the set boundary temperature, higher percentages were observed for lower temperatures and flow rates. We used the flow and heat transport simulator TOUGH2 to develop a numerical model of our laboratory setting. Given
Extensive numerical study of a D-brane, anti-D-brane system in AdS5/CFT4
International Nuclear Information System (INIS)
Hegedűs, Árpád
2015-01-01
In this paper the hybrid-NLIE approach of http://dx.doi.org/10.1007/JHEP08(2012)022 is extended to the ground state of a D-brane anti-D-brane system in AdS/CFT. The hybrid-NLIE equations presented in the paper are finite component alternatives of the previously proposed TBA equations and they admit an appropriate framework for the numerical investigation of the ground state of the problem. Straightforward numerical iterative methods fail to converge, thus new numerical methods are worked out to solve the equations. Our numerical data confirm the previous TBA data. In view of the numerical results the mysterious L=1 case is also commented in the paper.
Type III CRISPR-Cas systems can provide redundancy to counteract viral escape from type I systems.
Silas, Sukrit; Lucas-Elio, Patricia; Jackson, Simon A; Aroca-Crevillén, Alejandra; Hansen, Loren L; Fineran, Peter C; Fire, Andrew Z; Sánchez-Amat, Antonio
2017-08-17
CRISPR-Cas-mediated defense utilizes information stored as spacers in CRISPR arrays to defend against genetic invaders. We define the mode of target interference and role in antiviral defense for two CRISPR-Cas systems in Marinomonas mediterranea . One system (type I-F) targets DNA. A second system (type III-B) is broadly capable of acquiring spacers in either orientation from RNA and DNA, and exhibits transcription-dependent DNA interference. Examining resistance to phages isolated from Mediterranean seagrass meadows, we found that the type III-B machinery co-opts type I-F CRISPR-RNAs. Sequencing and infectivity assessments of related bacterial and phage strains suggests an 'arms race' in which phage escape from the type I-F system can be overcome through use of type I-F spacers by a horizontally-acquired type III-B system. We propose that the phage-host arms race can drive selection for horizontal uptake and maintenance of promiscuous type III interference modules that supplement existing host type I CRISPR-Cas systems.
Numerical simulations of the melting behavior of bulk and nanometer-sized Cu systems
International Nuclear Information System (INIS)
Manai, G.; Delogu, F.
2007-01-01
Molecular dynamics simulations have been employed to investigate the melting mechanisms of four different Cu systems consisting of a surface-free crystalline bulk, a semi-crystal terminating with a free surface and two unsupported particles with a radius of about 4 and 8 nm, respectively. Starting from a relaxed configuration at 300 K, the systems were gradually heated up to the characteristic melting points. The surface-free bulk system underwent homogeneous melting at the limit of superheating, whereas the melting of the semi-crystal and of the nanometer-sized particles occurred with heterogeneous features. In these latter cases, the structural and energetic properties revealed a two-state character with a definite difference between disordered surface layers and bulk-like interiors. In addition, the melting point and the latent heat of fusion of the nanometer-sized particles were significantly depressed with respect to the ones of the semi-crystal, approximately corresponding to the equilibrium values. Pre-melting phenomena took place at the free surfaces at temperatures significantly below the melting point, determining the formation of a solid-liquid interface. Numerical findings indicate that in all the cases the onset of melting is connected with the proliferation and migration of lattice defects and that an intimate relationship exists between homogeneous and heterogeneous melting mechanisms
International Nuclear Information System (INIS)
Owolabi, Kolade M.
2016-01-01
The aim of this paper is to examine pattern formation in the sub— and super-diffusive scenarios and compare it with that of classical or standard diffusive processes in two-component fractional reaction-diffusion systems that modeled a predator-prey dynamics. The focus of the work concentrates on the use of two separate mathematical techniques, we formulate a Fourier spectral discretization method as an efficient alternative technique to solve fractional reaction-diffusion problems in higher-dimensional space, and later advance the resulting systems of ODEs in time with the adaptive exponential time-differencing solver. Obviously, the fractional Fourier approach is able to achieve spectral convergence up to machine precision regardless of the fractional order α, owing to the fact that our approach is able to give full diagonal representation of the fractional operator. The complexity of the dynamics in this system is theoretically discussed and graphically displayed with some examples and numerical simulations in one, two and three dimensions.
Numerical verification of B-WIM system using reaction force signals
International Nuclear Information System (INIS)
Chang, Sung Jin; Kim, Nam Sik
2012-01-01
Bridges are ones of fundamental facilities for roads which become social overhead capital facilities and they are designed to get safety in their life cycles. However as time passes, bridge can be damaged by changes of external force and traffic environments. Therefore, a bridge should be repaired and maintained for extending its life cycle. The working load on a bridge is one of the most important factors for safety, it should be calculated accurately. The most important load among working loads is live load by a vehicle. Thus, the travel characteristics and weight of vehicle can be useful for bridge maintenance if they were estimated with high reliability. In this study, a B-WIM system in which the bridge is used for a scale have been developed for measuring the vehicle loads without the vehicle stop. The vehicle loads can be estimated by the developed B-WIM system with the reaction responses from the supporting points. The algorithm of developed B-WIM system have been verified by numerical analysis
International Nuclear Information System (INIS)
Kobayashi, Yasuhiro; Takamoto, Masanori; Nonaka, Hisanori; Yamada, Naoyuki
1994-01-01
A scheduling system has been developed by integrating symbolic processing functions for constraint handling and modification guidance, with numeric processing functions for schedule optimization and evaluation. The system is composed of an automatic schedule generation module, interactive schedule revision module and schedule evaluation module. The goal of the problem solving is the flattening of the daily resources requirement throughout the scheduling period. The automatic schedule generation module optimizes the initial schedule according to the formulatable portion of requirement description specified in a predicate-like language. A planning engineer refines the near-goal schedule through a knowledge-based interactive optimization process to obtain the goal schedule which fully covers the requirement description, with the interactive schedule revision module and schedule evaluation module. A scheduling system has been implemented on the basis of the proposed problem solving framework and experimentally applied to real-world sized scheduling problems for plant construction. With a result of the overall plant construction scheduling, a section schedule optimization process is described with the emphasis on the symbolic processing functions. (author)
Shah, Jay; Williams, Wyn; Almeida, Trevor P; Nagy, Lesleis; Muxworthy, Adrian R; Kovács, András; Valdez-Grijalva, Miguel A; Fabian, Karl; Russell, Sara S; Genge, Matthew J; Dunin-Borkowski, Rafal E
2018-03-21
Recordings of magnetic fields, thought to be crucial to our solar system's rapid accretion, are potentially retained in unaltered nanometric low-Ni kamacite (~ metallic Fe) grains encased within dusty olivine crystals, found in the chondrules of unequilibrated chondrites. However, most of these kamacite grains are magnetically non-uniform, so their ability to retain four-billion-year-old magnetic recordings cannot be estimated by previous theories, which assume only uniform magnetization. Here, we demonstrate that non-uniformly magnetized nanometric kamacite grains are stable over solar system timescales and likely the primary carrier of remanence in dusty olivine. By performing in-situ temperature-dependent nanometric magnetic measurements using off-axis electron holography, we demonstrate the thermal stability of multi-vortex kamacite grains from the chondritic Bishunpur meteorite. Combined with numerical micromagnetic modeling, we determine the stability of the magnetization of these grains. Our study shows that dusty olivine kamacite grains are capable of retaining magnetic recordings from the accreting solar system.
The role of numerical simulation for the development of an advanced HIFU system
Okita, Kohei; Narumi, Ryuta; Azuma, Takashi; Takagi, Shu; Matumoto, Yoichiro
2014-10-01
High-intensity focused ultrasound (HIFU) has been used clinically and is under clinical trials to treat various diseases. An advanced HIFU system employs ultrasound techniques for guidance during HIFU treatment instead of magnetic resonance imaging in current HIFU systems. A HIFU beam imaging for monitoring the HIFU beam and a localized motion imaging for treatment validation of tissue are introduced briefly as the real-time ultrasound monitoring techniques. Numerical simulations have a great impact on the development of real-time ultrasound monitoring as well as the improvement of the safety and efficacy of treatment in advanced HIFU systems. A HIFU simulator was developed to reproduce ultrasound propagation through the body in consideration of the elasticity of tissue, and was validated by comparison with in vitro experiments in which the ultrasound emitted from the phased-array transducer propagates through the acrylic plate acting as a bone phantom. As the result, the defocus and distortion of the ultrasound propagating through the acrylic plate in the simulation quantitatively agree with that in the experimental results. Therefore, the HIFU simulator accurately reproduces the ultrasound propagation through the medium whose shape and physical properties are well known. In addition, it is experimentally confirmed that simulation-assisted focus control of the phased-array transducer enables efficient assignment of the focus to the target. Simulation-assisted focus control can contribute to design of transducers and treatment planning.
Numerical heat transfer model for frost protection of citrus fruits by water from a spraying system
Directory of Open Access Journals (Sweden)
Issa Roy J.
2012-01-01
Full Text Available A simplified model is developed to simulate the conditions associated with the protection of fruits from frost damage using water from a spraying system. The model simulates the movement of the solidifying water front on a single fruit, and based on that determines the spray frequency needed for a water film to continuously surround the ice-coated fruit to prevent the fruit temperature from dropping below 0ºC. Simulations are presented for the frost protection of sweet oranges (citrus sinensis. The effect of environmental conditions such as air temperature, air velocity, surface radiation and water film evaporation on the development of the ice layer encasing is considered. Simulations show the effect the encasing ice sheet thickness has on the fruit temperature if water from a spraying system is turned off permanently. Experimental tests are also conducted to determine the change in the thermal properties of citrus sinensis for operating temperatures that range from above freezing to sub-freezing. The results of the experimental tests and the numerical simulations shall lead to a better understanding of fruit protection from frost damage by the application of water from a spraying system.
Numerical calculation on infrared characteristics of the special vehicle exhaust system
Feng, Yun-song; Li, Xiao-xia; Jin, Wei
2017-10-01
For mastery of infrared radiation characteristics and flow field of the special vehicle exhaust system, first, a physical model of the special vehicle exhaust system is established with the Gambit, and the mathematical model of flow field is determined. Secondly, software Fluent6.3 is used to simulated the 3-D exterior flow field of the special vehicle exhaust system, and the datum of flow field, such as temperature, pressure and density, are obtained. Thirdly, based on the plume temperature, the special vehicle exhaust space is divided. The exhaust is equivalent to a gray-body. A calculating model of the vehicle exhaust infrared radiation is established, and the exhaust infrared radiation characteristics are calculated by the software MATLAB, then the spatial distribution curves are drawn. Finally, the numerical results are analyzing, and the basic laws of the special vehicle exhaust infrared radiation are explored. The results show that with the increase of the engine speed, the temperature of the exhaust pipe wall of the special vehicle increases, and the temperature and pressure of the exhaust gas flow field increase, which leads to the enhancement of the infrared radiation intensity
An integrated numerical and physical modeling system for an enhanced in situ bioremediation process
International Nuclear Information System (INIS)
Huang, Y.F.; Huang, G.H.; Wang, G.Q.; Lin, Q.G.; Chakma, A.
2006-01-01
Groundwater contamination due to releases of petroleum products is a major environmental concern in many urban districts and industrial zones. Over the past years, a few studies were undertaken to address in situ bioremediation processes coupled with contaminant transport in two- or three-dimensional domains. However, they were concentrated on natural attenuation processes for petroleum contaminants or enhanced in situ bioremediation processes in laboratory columns. In this study, an integrated numerical and physical modeling system is developed for simulating an enhanced in situ biodegradation (EISB) process coupled with three-dimensional multiphase multicomponent flow and transport simulation in a multi-dimensional pilot-scale physical model. The designed pilot-scale physical model is effective in tackling natural attenuation and EISB processes for site remediation. The simulation results demonstrate that the developed system is effective in modeling the EISB process, and can thus be used for investigating the effects of various uncertainties. - An integrated modeling system was developed to enhance in situ bioremediation processes
Numerical scheme of WAHA code for simulation of fast transients in piping systems
International Nuclear Information System (INIS)
Iztok Tiselj
2005-01-01
terms: A δΨ-vector/δt = S-vector relaxation Convective terms and source terms due to the smooth area change, wall friction and volumetric forces are solved in the first sub step. Eigenvalues and eigenvectors of the system are found numerically. Such approach allows easier introduction of the new correlations, which might contain derivatives. Non-relaxation source terms in Eq. (3) are integrated with upwind discretization and with the same time step as the convection terms. Relaxation source terms: inter-phase heat, mass and momentum exchange terms are stiff, i.e., their characteristic time scales can be much shorter that the time scales of the hyperbolic part of the equations. Integration of the relaxation sources within the operator-splitting scheme - Eq. (4) - is performed with variable time steps, which depend on the stiffness of the source terms. Up-winding is not used for calculation of the relaxation source terms. (author)
Design type testing for digital instrumentation and control systems
International Nuclear Information System (INIS)
Bastl, W.; Mohns, G.
1997-01-01
The design type qualification of digital safety instrumentation and control is outlined. Experience shows that the concepts discussed, derived from codes, guidelines and standards, achieve useful results. It has likewise become clear that the systematics of design type qualification of the hardware components is also applicable to the software components. Design type qualification of the software, a premiere, could be performed unexpectedly smoothly. The hardware design type qualification proved that the hardware as a substrate of functionality and reliability is an issue that demands full attention, as compared to conventional systems. Another insight is that design qualification of digital instrumentation and control systems must include plant-independent systems tests. Digital instrumentation and control systems simply work very differently from conventional control systems, so that this testing modality is inevitable. (Orig./CB) [de
A common type system for clinical natural language processing
Directory of Open Access Journals (Sweden)
Wu Stephen T
2013-01-01
Full Text Available Abstract Background One challenge in reusing clinical data stored in electronic medical records is that these data are heterogenous. Clinical Natural Language Processing (NLP plays an important role in transforming information in clinical text to a standard representation that is comparable and interoperable. Information may be processed and shared when a type system specifies the allowable data structures. Therefore, we aim to define a common type system for clinical NLP that enables interoperability between structured and unstructured data generated in different clinical settings. Results We describe a common type system for clinical NLP that has an end target of deep semantics based on Clinical Element Models (CEMs, thus interoperating with structured data and accommodating diverse NLP approaches. The type system has been implemented in UIMA (Unstructured Information Management Architecture and is fully functional in a popular open-source clinical NLP system, cTAKES (clinical Text Analysis and Knowledge Extraction System versions 2.0 and later. Conclusions We have created a type system that targets deep semantics, thereby allowing for NLP systems to encapsulate knowledge from text and share it alongside heterogenous clinical data sources. Rather than surface semantics that are typically the end product of NLP algorithms, CEM-based semantics explicitly build in deep clinical semantics as the point of interoperability with more structured data types.
A common type system for clinical natural language processing.
Wu, Stephen T; Kaggal, Vinod C; Dligach, Dmitriy; Masanz, James J; Chen, Pei; Becker, Lee; Chapman, Wendy W; Savova, Guergana K; Liu, Hongfang; Chute, Christopher G
2013-01-03
One challenge in reusing clinical data stored in electronic medical records is that these data are heterogenous. Clinical Natural Language Processing (NLP) plays an important role in transforming information in clinical text to a standard representation that is comparable and interoperable. Information may be processed and shared when a type system specifies the allowable data structures. Therefore, we aim to define a common type system for clinical NLP that enables interoperability between structured and unstructured data generated in different clinical settings. We describe a common type system for clinical NLP that has an end target of deep semantics based on Clinical Element Models (CEMs), thus interoperating with structured data and accommodating diverse NLP approaches. The type system has been implemented in UIMA (Unstructured Information Management Architecture) and is fully functional in a popular open-source clinical NLP system, cTAKES (clinical Text Analysis and Knowledge Extraction System) versions 2.0 and later. We have created a type system that targets deep semantics, thereby allowing for NLP systems to encapsulate knowledge from text and share it alongside heterogenous clinical data sources. Rather than surface semantics that are typically the end product of NLP algorithms, CEM-based semantics explicitly build in deep clinical semantics as the point of interoperability with more structured data types.
International Nuclear Information System (INIS)
Kaneko, Yuta; Yoshida, Zensho
2014-01-01
Introducing a Clebsch-like parameterization, we have formulated a canonical Hamiltonian system on a symplectic leaf of reduced magnetohydrodynamics. An interesting structure of the equations is in that the Lorentz-force, which is a quadratic nonlinear term in the conventional formulation, appears as a linear term −ΔQ, just representing the current density (Q is a Clebsch variable, and Δ is the two-dimensional Laplacian); omitting this term reduces the system into the two-dimensional Euler vorticity equation of a neutral fluid. A heuristic estimate shows that current sheets grow exponentially (even in a fully nonlinear regime) together with the action variable P that is conjugate to Q. By numerical simulation, the predicted behavior of the canonical variables, yielding exponential growth of current sheets, has been demonstrated
Numerical Feedback Stabilization with Applications to Networks
Directory of Open Access Journals (Sweden)
Simone Göttlich
2017-01-01
Full Text Available The focus is on the numerical consideration of feedback boundary control problems for linear systems of conservation laws including source terms. We explain under which conditions the numerical discretization can be used to design feedback boundary values for network applications such as electric transmission lines or traffic flow systems. Several numerical examples illustrate the properties of the results for different types of networks.
Numeric processor and text manipulator for the ''MASTER CONTROL'' data-base-management system
International Nuclear Information System (INIS)
Kuhn, R.W.
1976-01-01
The numeric and text processor of the MASTER CONTROL (MCP) data-base-management system permits the user to define fields and arrays that are functionally dependent on the data retained in a data base. This allows the storage of only the essential and unique information and data, and the calculation of derivable quantities as required. The derived quantity can be expressed as an arithmetic expression, that is, a functional relationship. Functions can be multiply subscripted and can be embedded within other functions at up to 58 levels. They can be stored either semi-permanently in a repertoire of functional relations, or they can be defined interactively from a terminal and used immediately for searching on the derived value. The processor also permits the conversion of literal strings into numbers, and vice versa. In addition, the user can define dictionaries that allow the expansion of keyed sentinels associated with records in the data base into fully descriptive expressions. This option can be used for cost-effective searching and data compaction. The functional definitions are reduced to Polish notation and stored in a disk file from which they are either retrieved on demand and evaluated according to the data of records specified or used in any given MASTER CONTROL command. The language used for the definitions of the numeric processor is essentially FORTRAN; most of the standard functions and over two dozen special functions are thus available. The functional processor provides a powerful technique for the integration of text and data for energy research and for scientific and technological work in general. MASTER CONTROL is operational at the Lawrence Livermore Laboratory (LLL) and at the Los Alamos Scientific Laboratory (LASL). 6 figures, 1 table
Experimental and numerical study of an evaporatively-cooled condenser of air-conditioning systems
International Nuclear Information System (INIS)
Islam, M.R.; Jahangeer, K.A.; Chua, K.J.
2015-01-01
The performance of an air-conditioning unit with evaporately-cooled condenser coil is studied experimentally and numerically. An experimental setup is fabricated by retrofitting a commercially available air-conditioning unit and installing comprehensive measuring sensors and controllers. Experimental result shows that the COP (Coefficient of Performance) of the evaporately-cooled air-conditioning unit increases by about 28% compared to the conventional air cooled air-conditioning unit. To analyze the heat and mass transfer processes involved in the evaporately-cooled condenser, a detailed theoretical model has been developed based on the fluid flow characteristics of the falling film and the thermodynamic aspect of the evaporation process. Simulated results agree well with experimental data. The numerical model provides new insights into the intrinsic links between operating variables and heat transfer characteristics of water film in evaluating the performance of evaporatively-cooled condenser system. Two heat transfer coefficients, namely, wall to bulk and bulk to interface are introduced and computed from the simulation results under different operating conditions. Finally, the overall heat transfer coefficient for the water film is computed and presented as a function of dimensionless variables which can conveniently be employed by engineers to design and analyze high performance evaporatively-cooled heat exchangers. - Highlights: • Performance of evaporatively-cooled condenser is investigated. • Local convective heat transfer coefficients of water film are determined. • Thermal resistance of water film is negligible. • Heat transfer with evaporated vapor plays significant role on performance. • Better condenser performance translates to an improvement in COP
Coupled circuit numerical analysis of eddy currents in an open MRI system
Akram, Md. Shahadat Hossain; Terada, Yasuhiko; Keiichiro, Ishi; Kose, Katsumi
2014-08-01
We performed a new coupled circuit numerical simulation of eddy currents in an open compact magnetic resonance imaging (MRI) system. Following the coupled circuit approach, the conducting structures were divided into subdomains along the length (or width) and the thickness, and by implementing coupled circuit concepts we have simulated transient responses of eddy currents for subdomains in different locations. We implemented the Eigen matrix technique to solve the network of coupled differential equations to speed up our simulation program. On the other hand, to compute the coupling relations between the biplanar gradient coil and any other conducting structure, we implemented the solid angle form of Ampere’s law. We have also calculated the solid angle for three dimensions to compute inductive couplings in any subdomain of the conducting structures. Details of the temporal and spatial distribution of the eddy currents were then implemented in the secondary magnetic field calculation by the Biot-Savart law. In a desktop computer (Programming platform: Wolfram Mathematica 8.0®, Processor: Intel(R) Core(TM)2 Duo E7500 @ 2.93 GHz; OS: Windows 7 Professional; Memory (RAM): 4.00 GB), it took less than 3 min to simulate the entire calculation of eddy currents and fields, and approximately 6 min for X-gradient coil. The results are given in the time-space domain for both the direct and the cross-terms of the eddy current magnetic fields generated by the Z-gradient coil. We have also conducted free induction decay (FID) experiments of eddy fields using a nuclear magnetic resonance (NMR) probe to verify our simulation results. The simulation results were found to be in good agreement with the experimental results. In this study we have also conducted simulations for transient and spatial responses of secondary magnetic field induced by X-gradient coil. Our approach is fast and has much less computational complexity than the conventional electromagnetic numerical
Numerical modeling of groundwater flow in the coastal aquifer system of Taranto (southern Italy)
De Filippis, Giovanna; Giudici, Mauro; Negri, Sergio; Margiotta, Stefano; Cattaneo, Laura; Vassena, Chiara
2014-05-01
The Mediterranean region is characterized by a strong development of coastal areas with a high concentration of water-demanding human activities, resulting in weakly controlled withdrawals of groundwater which accentuate the saltwater intrusion phenomenon. The worsening of groundwater quality is a huge problem especially for those regions, like Salento (southern Italy), where a karst aquifer system represents the most important water resource because of the deficiency of a well developed superficial water supply. In this frame, the first 2D numerical model describing the groundwater flow in the karst aquifer of Salento peninsula was developed by Giudici et al. [1] at the regional scale and then improved by De Filippis et al. [2]. In particular, the estimate of the saturated thickness of the deep aquifer highlighted that the Taranto area is particularly sensitive to the phenomenon of seawater intrusion, both for the specific hydrostratigraphic configuration and for the presence of highly water-demanding industrial activities. These remarks motivate a research project which is part of the research program RITMARE (The Italian Research for the Sea), within which a subprogram is specifically dedicated to the problem of the protection and preservation of groundwater quality in Italian coastal aquifers and in particular, among the others, in the Taranto area. In this context, the CINFAI operative unit aims at providing a contribution to the characterization of groundwater in the study area. The specific objectives are: a. the reconstruction of the groundwater dynamic (i.e., the preliminary identification of a conceptual model for the aquifer system and the subsequent modeling of groundwater flow in a multilayered system which is very complex from the hydrostratigraphical point of view); b. the characterization of groundwater outflows through submarine and subaerial springs and the water exchanges with the shallow coastal water bodies (e.g. Mar Piccolo) and the off
Combined analytical and numerical approaches in Dynamic Stability analyses of engineering systems
Náprstek, Jiří
2015-03-01
Dynamic Stability is a widely studied area that has attracted many researchers from various disciplines. Although Dynamic Stability is usually associated with mechanics, theoretical physics or other natural and technical disciplines, it is also relevant to social, economic, and philosophical areas of our lives. Therefore, it is useful to occasionally highlight the general aspects of this amazing area, to present some relevant examples and to evaluate its position among the various branches of Rational Mechanics. From this perspective, the aim of this study is to present a brief review concerning the Dynamic Stability problem, its basic definitions and principles, important phenomena, research motivations and applications in engineering. The relationships with relevant systems that are prone to stability loss (encountered in other areas such as physics, other natural sciences and engineering) are also noted. The theoretical background, which is applicable to many disciplines, is presented. In this paper, the most frequently used Dynamic Stability analysis methods are presented in relation to individual dynamic systems that are widely discussed in various engineering branches. In particular, the Lyapunov function and exponent procedures, Routh-Hurwitz, Liénard, and other theorems are outlined together with demonstrations. The possibilities for analytical and numerical procedures are mentioned together with possible feedback from experimental research and testing. The strengths and shortcomings of these approaches are evaluated together with examples of their effective complementing of each other. The systems that are widely encountered in engineering are presented in the form of mathematical models. The analyses of their Dynamic Stability and post-critical behaviour are also presented. The stability limits, bifurcation points, quasi-periodic response processes and chaotic regimes are discussed. The limit cycle existence and stability are examined together with their
International Nuclear Information System (INIS)
Iniguez, J.; Raposo, V.
2010-01-01
The design and analysis of a small prototype of a magnetic levitation system at low-speed using a Halbach-type magnet array is presented here. For that purpose, we have arranged a copper rim over a carbon fiber wheel, which is driven by an electric motor in presence of the magnet array, in such a manner that allows performing the experiment readily. The analysis of the system is undertaken under a two-dimensional (2D)-approach which permits computing and extending the study of our model to higher speeds. Our work is completed with a series of experimental measurements of lift and drag forces for different circumstances. Initially, the drag force is significant but after the compensation speed (when both forces balance) it slowly decreases. Conversely, the lift force becomes progressively bigger in such a manner that it attains quickly noteworthy values. We observe that the theoretical compensation speed is always minor than the experimental one and that the measured values for both forces are slightly smaller than the expected, although the main features of the experiment are well matched by our numerical simulation.
Energy Technology Data Exchange (ETDEWEB)
Iniguez, J., E-mail: nacho@usal.e [Departamento de Fisica Aplicada, Universidad de Salamanca, E-37071 (Spain); Raposo, V. [Departamento de Fisica Aplicada, Universidad de Salamanca, E-37071 (Spain)
2010-05-15
The design and analysis of a small prototype of a magnetic levitation system at low-speed using a Halbach-type magnet array is presented here. For that purpose, we have arranged a copper rim over a carbon fiber wheel, which is driven by an electric motor in presence of the magnet array, in such a manner that allows performing the experiment readily. The analysis of the system is undertaken under a two-dimensional (2D)-approach which permits computing and extending the study of our model to higher speeds. Our work is completed with a series of experimental measurements of lift and drag forces for different circumstances. Initially, the drag force is significant but after the compensation speed (when both forces balance) it slowly decreases. Conversely, the lift force becomes progressively bigger in such a manner that it attains quickly noteworthy values. We observe that the theoretical compensation speed is always minor than the experimental one and that the measured values for both forces are slightly smaller than the expected, although the main features of the experiment are well matched by our numerical simulation.
Intelligent micro blood typing system using a fuzzy algorithm
International Nuclear Information System (INIS)
Kang, Taeyun; Cho, Dong-Woo; Lee, Seung-Jae; Kim, Yonggoo; Lee, Gyoo-Whung
2010-01-01
ABO typing is the first analysis performed on blood when it is tested for transfusion purposes. The automated machines used in hospitals for this purpose are typically very large and the process is complicated. In this paper, we present a new micro blood typing system that is an improved version of our previous system (Kang et al 2004 Trans. ASME, J. Manuf. Sci. Eng. 126 766, Lee et al 2005 Sensors Mater. 17 113). This system, fabricated using microstereolithography, has a passive valve for controlling the flow of blood and antibodies. The intelligent micro blood typing system has two parts: a single-line micro blood typing device and a fuzzy expert system for grading the strength of agglutination. The passive valve in the single-line micro blood typing device makes the blood stop at the entrance of a micro mixer and lets it flow again after the blood encounters antibodies. Blood and antibodies are mixed in the micro mixer and agglutination occurs in the chamber. The fuzzy expert system then determines the degree of agglutination from images of the agglutinated blood. Blood typing experiments using this device were successful, and the fuzzy expert system produces a grading decision comparable to that produced by an expert conducting a manual analysis
Numerical analysis of natural ventilation system in a studio apartment in Bangladesh
Kabir, K. M. Ariful; Hasan, Md. Rakibul; Khan, Md. Abdul Hakim
2017-07-01
The study of temperature and air flow for natural ventilation system has been investigated numerically. A finite element model for studio apartment was developed with the aim of achieving detail energy allocation in the real buildings during the transient process in the walls and internal air. A tool of computational fluid dynamics (CFD) is employed to assist the process. In the tropical regions most of the energy is consumed by the heating, cooling and ventilation appliances. Therefore, the optimize ventilation system will be a suitable and valid option for the saving of energy from the household sector to increase cooling performance and ensuring thermal comfort as well. A mathematical exploration is carried out on full scale dwelling and small scale model and indication is given on the relevance of such a comparison. Calculations are carried out with household heat sources for calm and windy period, but without any human. As expected, for windy periods, the wind is the main driving force behind the internal air flow. However, in calm periods for unsteady flow the internal airflow looks like more complexes through observation.
Bucs, Szilard; Radu, Andrea I.; Lavric, Vasile; Vrouwenvelder, Johannes S.; Picioreanu, Cristian
2014-01-01
Feed spacers and hydrodynamics have been found relevant for the impact of biofouling on performance in reverse osmosis (RO) and nanofiltration (NF) membrane systems.The objectives of this study on biofouling development were to determine the impact of (i) linear flow velocity and bacterial cell load, (ii) biomass location and (iii) various feed spacer geometries as applied in practice as well as a modified geometry spacer.A three-dimensional mathematical model for biofouling of feed spacer channels including hydrodynamics, solute mass transport and biofilm formation was developed in COMSOL Multiphysics and MATLAB software.Results of this study indicate that the feed channel pressure drop increase caused by biofilm formation can be reduced by using thicker and/or modified feed spacer geometry and/or a lower flow rate in the feed channel. The increase of feed channel pressure drop by biomass accumulation is shown to be strongly influenced by the location of biomass. Results of numerical simulations are in satisfactory agreement with experimental data, indicating that this micro-scale mechanistic model is representative for practice. The developed model can help to understand better the biofouling process of spiral-wound RO and NF membrane systems and to develop strategies to reduce and control biofouling. © 2013 Elsevier B.V.
Bucs, Szilard
2014-06-01
Feed spacers and hydrodynamics have been found relevant for the impact of biofouling on performance in reverse osmosis (RO) and nanofiltration (NF) membrane systems.The objectives of this study on biofouling development were to determine the impact of (i) linear flow velocity and bacterial cell load, (ii) biomass location and (iii) various feed spacer geometries as applied in practice as well as a modified geometry spacer.A three-dimensional mathematical model for biofouling of feed spacer channels including hydrodynamics, solute mass transport and biofilm formation was developed in COMSOL Multiphysics and MATLAB software.Results of this study indicate that the feed channel pressure drop increase caused by biofilm formation can be reduced by using thicker and/or modified feed spacer geometry and/or a lower flow rate in the feed channel. The increase of feed channel pressure drop by biomass accumulation is shown to be strongly influenced by the location of biomass. Results of numerical simulations are in satisfactory agreement with experimental data, indicating that this micro-scale mechanistic model is representative for practice. The developed model can help to understand better the biofouling process of spiral-wound RO and NF membrane systems and to develop strategies to reduce and control biofouling. © 2013 Elsevier B.V.
Numerical simulation of a PSA system using a pore diffusion model
Energy Technology Data Exchange (ETDEWEB)
Raghavan, N S; Hassan, M M; Ruthven, D M
1986-01-01
A mathematical model has been developed for a pressure swing adsorption (PSA) system (heatless drier) in which the controlling resistance to mass transfer is diffusion within the pores of the adsorbent particles. The model equations are solved numerically by the method of orthogonal collocation. By comparing the solutions from this model with the solutions derived from the simpler linear driving force model it is shown that the simpler model provides an acceptable approximation provided that the coefficient (omega in eq. (1)) is chosen correctly. The appropriate value of omega depends on the cycle time and to a lesser extent on the degree of isotherm non-linearity and the nature of the diffusion mechanism, varying from about 40 at low cycle times to 15 or even lower at large cycle times. However, over a fairly wide range of conditions typical of PSA operation the linear driving force model with omega = 40 provides an acceptable approximation, except in the initial region of the transient. The value of omega recommended by Glueckauf for modelling of a fixed bed (omega = 15) is approached only at rather large cycle times and is clearly inappropriate for a PSA system under most practical conditions.
International Nuclear Information System (INIS)
Kiseleva, L.G.; Orlov, V.V.
1988-01-01
The numerical-experiment approach in the framework of the general gravitational three-body problem has been used to investigate the dynamical evolution of triple systems of gaseous protogalactic fragments. The masses of the fragments are equal, the initial velocities zero. The initial positions were specified by uniform scanning in the region D of all possible initial configurations. Calculations were continued until the first two-body encounter of the fragments. Different values of the fragment radii at this times were considered, namely, r in the interval [0.001, 0.1]d, where d is the mean diameter of the system. It is shown that for such r the pair of gaseous fragments coalesces in the majority of cases (from 50.2% for r = 0.001d to 96.7% for r = 0.1d). The mean specific angular momentum of their relative motion, which becomes spin angular momentum of the coalescence product, is (0.8 +- 1.0)/centered dot/10 29 /root/μl cm 2 sec for the most probable value r = 10l kpc (the masses of the fragments are 5/centered dot/10 10 μM/circled dot/; l and μ are scale factors), this agreeing in order of magnitude with the specific angular momenta of disk galaxies if l, μ /approximately/ 1. For each value of r, a continuous zone of initial configurations corresponding to coalescences is identified in the region D
Numerical simulations of recent proton acceleration experiments with sub-100 TW laser systems
International Nuclear Information System (INIS)
Sinigardi, Stefano
2016-01-01
Recent experiments carried out at the Italian National Research Center, National Optics Institute Department in Pisa, are showing interesting results regarding maximum proton energies achievable with sub-100 TW laser systems. While laser systems are being continuously upgraded in laboratories around the world, at the same time a new trend on stabilizing and making ion acceleration results reproducible is growing in importance. Almost all applications require a beam with fixed performance, so that the energy spectrum and the total charge exhibit moderate shot to shot variations. This result is surely far from being achieved, but many paths are being explored in order to reach it. Some of the reasons for this variability come from fluctuations in laser intensity and focusing, due to optics instability. Other variation sources come from small differences in the target structure. The target structure can vary substantially, when it is impacted by the main pulse, due to the prepulse duration and intensity, the shape of the main pulse and the total energy deposited. In order to qualitatively describe the prepulse effect, we will present a two dimensional parametric scan of its relevant parameters. A single case is also analyzed with a full three dimensional simulation, obtaining reasonable agreement between the numerical and the experimental energy spectrum.
A deteriorating two-system with two repair modes and sojourn times phase-type distributed
International Nuclear Information System (INIS)
Montoro-Cazorla, Delia; Perez-Ocon, Rafael
2006-01-01
We study a two-unit cold standby system in steady-state. The online unit goes through a finite number of stages of successive degradation preceding the failure. The units are reparable, there is a repairman and two types of maintenance are considered, preventive and corrective. The preventive repair aims to improve the degradation of a unit being operative. The corrective repair is necessary when the unit fails. We will assume that the preventive repair will be interrupted in favour of a corrective repair in order to increase the availability of the system. The random operational and repair times follow phase-type distributions. For this system, the stationary probability vector, the replacement times, and the involved costs are calculated. An optimisation problem is illustrated by a numerical example. In this, the optimal degradation stage for the preventive repair of the online unit is determined by taking into account the system availability and the incurred costs
A deteriorating two-system with two repair modes and sojourn times phase-type distributed
Energy Technology Data Exchange (ETDEWEB)
Montoro-Cazorla, Delia [Departamento de Estadistica e I.O., Escuela Politecnica de Linares, Universidad de Jaen, 23700 Linares, Jaen (Spain); Perez-Ocon, Rafael [Departamento de Estadistica e I.O., Facultad de Ciencias, Universidad de Granada, Granada 18071 (Spain)]. E-mail: rperezo@ugr.es
2006-01-01
We study a two-unit cold standby system in steady-state. The online unit goes through a finite number of stages of successive degradation preceding the failure. The units are reparable, there is a repairman and two types of maintenance are considered, preventive and corrective. The preventive repair aims to improve the degradation of a unit being operative. The corrective repair is necessary when the unit fails. We will assume that the preventive repair will be interrupted in favour of a corrective repair in order to increase the availability of the system. The random operational and repair times follow phase-type distributions. For this system, the stationary probability vector, the replacement times, and the involved costs are calculated. An optimisation problem is illustrated by a numerical example. In this, the optimal degradation stage for the preventive repair of the online unit is determined by taking into account the system availability and the incurred costs.
Propagation of a general-type beam through a truncated fractional Fourier transform optical system.
Zhao, Chengliang; Cai, Yangjian
2010-03-01
Paraxial propagation of a general-type beam through a truncated fractional Fourier transform (FRT) optical system is investigated. Analytical formulas for the electric field and effective beam width of a general-type beam in the FRT plane are derived based on the Collins formula. Our formulas can be used to study the propagation of a variety of laser beams--such as Gaussian, cos-Gaussian, cosh-Gaussian, sine-Gaussian, sinh-Gaussian, flat-topped, Hermite-cosh-Gaussian, Hermite-sine-Gaussian, higher-order annular Gaussian, Hermite-sinh-Gaussian and Hermite-cos-Gaussian beams--through a FRT optical system with or without truncation. The propagation properties of a Hermite-cos-Gaussian beam passing through a rectangularly truncated FRT optical system are studied as a numerical example. Our results clearly show that the truncated FRT optical system provides a convenient way for laser beam shaping.
Propagation of sech2-type solitary waves in higher-order KdV-type systems
International Nuclear Information System (INIS)
Ilison, O.; Salupere, A.
2005-01-01
Wave propagation in microstructured media is essentially influenced by nonlinear and dispersive effects. The simplest model governing these effects results in the Korteweg-de Vries (KdV) equation. In the present paper a KdV-type evolution equation, including the third- and fifth-order dispersive and the fourth-order nonlinear terms, is used for modelling the wave propagation in microstructured solids like martensitic-austenitic alloys. The model equation is solved numerically under localised initial conditions. Possible solution types are defined and discussed. The existence of a threshold is established. Below the threshold, the relatively small solitary waves decay in time. However, if the amplitude exceeds a certain threshold, i.e., the critical value, then such a solitary wave can propagate with nearly a constant speed and amplitude and consequently conserve the energy
Rabani, Ramin; Faghih, Ahmadreza K.; Rabani, Mehrdad; Rabani, Mehran
2014-05-01
In this study, passive cooling of a room using a solar chimney and water spraying system in the room inlet vents is simulated numerically in Yazd, Iran (a hot and arid city with very high solar radiation). The performance of this system has been investigated for the warmest day of the year (5 August) which depends on the variation of some parameters such as water flow rate, solar heat flux, and inlet air temperature. In order to get the best performance of the system for maximum air change and also absorb the highest solar heat flux by the absorber in the warmest time of the day, different directions (West, East, North and South) have been studied and the West direction has been selected as the best direction. The minimum amount of water used in spraying system to set the inside air averaged relative humidity <65 % is obtained using trial and error method. The simulation results show that this proposed system decreases the averaged air temperature in the middle of the room by 9-14 °C and increases the room relative humidity about 28-45 %.
International Nuclear Information System (INIS)
Mukai, Eiichiro; Makino, Naoki.
1991-01-01
We have analyzed MRI in 33 patients with several forms of spinocerebellar degeneration; 17 with multiple system atrophy, 10 with Holmes type, and 6 with Menzel-Joseph type. The MRIs were obtained using a 1.5-T GEMR System. Patients with multiple system atrophy demonstrated: atrophy of the brain stem, particularly basis pontis; decreased signal intensity of the white matter of pons; atrophy of the white matter of cerebellum; atrophy and decreased signal intensity of the putamen, particularly along their lateral and posterior portions; and atrophy of the cerebrum. Patients with Holmes type showed: atrophy of the cerebellum; atrophy of the vermis more than hemispheres; and nuclei of the cerebellum with no decreased intensity on T 2 -weighted sequences. Patients with Menzel-Joseph type demonstrated moderate atrophy of the brain stem and mild atrophy of the white matter of cerebellum. MRI is a useful diagnostic tool in the management of the spinocerebellar degeneration. (author)
Brezinski, C
2012-01-01
Numerical analysis has witnessed many significant developments in the 20th century. This book brings together 16 papers dealing with historical developments, survey papers and papers on recent trends in selected areas of numerical analysis, such as: approximation and interpolation, solution of linear systems and eigenvalue problems, iterative methods, quadrature rules, solution of ordinary-, partial- and integral equations. The papers are reprinted from the 7-volume project of the Journal of Computational and Applied Mathematics on '/homepage/sac/cam/na2000/index.html<
From Flow Logic to static type systems for coordination languages
DEFF Research Database (Denmark)
De Nicola, Rocco; Gorla, Daniele; Hansen, Rene Rydhof
2010-01-01
checks; therefore, the correctness properties cannot be statically enforced. By contrast, static analysis approaches based on Flow Logic usually guarantee properties statically. In this paper, we show how the insights from the Flow Logic approach can be used to construct a type system for statically......Coordination languages are often used to describe open-ended systems. This makes it challenging to develop tools for guaranteeing the security of the coordinated systems and the correctness of their interaction. Successful approaches to this problem have been based on type systems with dynamic...
From Flow Logic to Static Type Systems in Coordination Languages
DEFF Research Database (Denmark)
De Nicola, Rocco; Gorla, Daniele; Hansen, René Rydhof
2008-01-01
; therefore, the correctness properties cannot be statically enforced. By contrast, static analysis approaches based on Flow Logic usually guarantee properties statically. In this paper we show how to combine these two approaches to obtain a static type system for describing secure access to tuple spaces......Coordination languages are often used to describe open ended systems. This makes it challenging to develop tools for guaranteeing security of the coordinated systems and correctness of their interaction. Successful approaches to this problem have been based on type systems with dynamic checks...
Controlling Unknown Saddle Type Steady States of Dynamical Systems with Latency in the Feedback Loop
DEFF Research Database (Denmark)
Tamasevicius, Arunas; Bumeliene, Skaidra; Tamaseviciute, Elena
2009-01-01
We suggest an adaptive control technique for stabilizing saddle type unstable steady states of dynamical systems. The controller is composed of an unstable and a stable high-pass filters operating in parallel. The mathematical model is considered analytically and numerically. The conjoint...... controller is sufficiently robust to time latencies in the feedback loop. In addition, it is not sensitive to the damping parameters of the system and is relatively fast. Experiments have been performed using a simplified version of the electronic Young-Silva circuit imitating behavior of the Duffing...
Bergamasco, A.; Budgell, W. P.; Carniel, S.; Sclavo, M.
2005-03-01
Conveyor belt circulation controls global climate through heat and water fluxes with atmosphere and from tropical to polar regions and vice versa. This circulation, commonly referred to as thermohaline circulation (THC), seems to have millennium time scale and nowadays--a non-glacial period--appears to be as rather stable. However, concern is raised by the buildup of CO2 and other greenhouse gases in the atmosphere (IPCC, Third assessment report: Climate Change 2001. A contribution of working group I, II and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change (Cambridge Univ. Press, UK) 2001, http://www.ipcc.ch) as these may affect the THC conveyor paths. Since it is widely recognized that dense-water formation sites act as primary sources in strengthening quasi-stable THC paths (Stommel H., Tellus131961224), in order to simulate properly the consequences of such scenarios a better understanding of these oceanic processes is needed. To successfully model these processes, air-sea-ice-integrated modelling approaches are often required. Here we focus on two polar regions using the Regional Ocean Modeling System (ROMS). In the first region investigated, the North Atlantic-Arctic, where open-ocean deep convection and open-sea ice formation and dispersion under the intense air-sea interactions are the major engines, we use a new version of the coupled hydrodynamic-ice ROMS model. The second area belongs to the Antarctica region inside the Southern Ocean, where brine rejections during ice formation inside shelf seas origin dense water that, flowing along the continental slope, overflow becoming eventually abyssal waters. Results show how nowadays integrated-modelling tasks have become more and more feasible and effective; numerical simulations dealing with large computational domains or challenging different climate scenarios can be run on multi-processors platforms and on systems like LINUX clusters, made of the same hardware as PCs, and
Ghotbi Ravandi, Ebrahim; Rahmannejad, Reza; Karimi-Nasab, Saeed; Sarrafi, Amir; Raoof, Amir
In this paper the main criteria of the water curtain system for unlined rock caverns (URCs) is described. By the application of numerical modeling and genetic programming (GP), a method for water curtain system pre-design for Iranian crude oil storage URCs (common dimension worldwide) is presented.
Numerical computation of inventory policies, based on the EOQ/sigma-x value for order-point systems
DEFF Research Database (Denmark)
Alstrøm, Poul
2001-01-01
This paper examines the numerical computation of two control parameters, order size and order point in the well-known inventory control model, an (s,Q)system with a beta safety strategy. The aim of the paper is to show that the EOQ/sigma-x value is both sufficient for controlling the system and e...
Numerical computation of inventory policies, based on the EOQ/sigma-x value for order-point systems
DEFF Research Database (Denmark)
Alstrøm, Poul
2000-01-01
This paper examines the numerical computation of two control parameters, order size and order point in the well-known inventory control model, an (s,Q)system with a beta safety strategy. The aim of the paper is to show that the EOQ/sigma-x value is both sufficient for controlling the system and e...
A higher-order numerical framework for stochastic simulation of chemical reaction systems.
Székely, Tamás
2012-07-15
BACKGROUND: In this paper, we present a framework for improving the accuracy of fixed-step methods for Monte Carlo simulation of discrete stochastic chemical kinetics. Stochasticity is ubiquitous in many areas of cell biology, for example in gene regulation, biochemical cascades and cell-cell interaction. However most discrete stochastic simulation techniques are slow. We apply Richardson extrapolation to the moments of three fixed-step methods, the Euler, midpoint and θ-trapezoidal τ-leap methods, to demonstrate the power of stochastic extrapolation. The extrapolation framework can increase the order of convergence of any fixed-step discrete stochastic solver and is very easy to implement; the only condition for its use is knowledge of the appropriate terms of the global error expansion of the solver in terms of its stepsize. In practical terms, a higher-order method with a larger stepsize can achieve the same level of accuracy as a lower-order method with a smaller one, potentially reducing the computational time of the system. RESULTS: By obtaining a global error expansion for a general weak first-order method, we prove that extrapolation can increase the weak order of convergence for the moments of the Euler and the midpoint τ-leap methods, from one to two. This is supported by numerical simulations of several chemical systems of biological importance using the Euler, midpoint and θ-trapezoidal τ-leap methods. In almost all cases, extrapolation results in an improvement of accuracy. As in the case of ordinary and stochastic differential equations, extrapolation can be repeated to obtain even higher-order approximations. CONCLUSIONS: Extrapolation is a general framework for increasing the order of accuracy of any fixed-step stochastic solver. This enables the simulation of complicated systems in less time, allowing for more realistic biochemical problems to be solved.
International Nuclear Information System (INIS)
Tanchuk, Victor; Grigoriev, Sergey; Lyublin, Boris; Maquet, Philippe; Senik, Konstantin; Pak, Sunil; Udintsev, Victor
2016-01-01
Highlights: • The cooling system of the ITER Generic Equatorial Port Plug (GEPP) is of a complicated combination of horizontal and vertical channels. • The calculation model for the entire GEPP cooling circuit comprising 12 sub-circuits and built up of 2421 finite-volume elements has been developed. • Transient analysis of this model simulating the draining procedure by the KORSAR/B1 code has been performed. • Water in amount of 263 g of initial 531 kg in the GEPP remains in the dead-ends of the DSM and DFW channels in 150 s of draining procedure. • Almost 3 h are required to boil off 263 g of water trapped in the dead-ends. - Abstract: For effective vacuum leak testing all cooling circuits serving the ITER vessel and in-vessel components shall be drained and dried so that after this procedure taking less than 100 h the purge gas passing through a component has water content less than 100 ppm. This process is four-stage, with the first stage using a short blast of compressed nitrogen to blow most of water in the coolant channels out of the circuit. This process is hindered by volumes which trap water due to gravity. To remove the trapped water, it is necessary, first, to heat up the structure by hot and compressed nitrogen, and then water is evaporated by depressurized nitrogen. The cooling system of the ITER Diagnostic Equatorial Port Plugs is of a complicated hydraulic configuration. The system branching might make difficult removal of water from the piping in the scheduled draining mode. The authors have proposed the KORSAR computation code to simulate draining of the GEPP cooling circuit. The numerical simulation performed has made it possible to describe the process dynamics during draining of the entire GEPP cooling circuit and to define the process time, amount and location of residual water and evolution of two-phase flow regime.
Energy Technology Data Exchange (ETDEWEB)
Tanchuk, Victor, E-mail: Victor.Tanchuk@sintez.niiefa.spb.su [JSC “D.V. Efremov Institute of Electrophysical Apparatus”, 196641 St. Petersburg (Russian Federation); Grigoriev, Sergey; Lyublin, Boris [JSC “D.V. Efremov Institute of Electrophysical Apparatus”, 196641 St. Petersburg (Russian Federation); Maquet, Philippe [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Senik, Konstantin [JSC “D.V. Efremov Institute of Electrophysical Apparatus”, 196641 St. Petersburg (Russian Federation); Pak, Sunil [National Fusion Research Institute, Daejeon (Korea, Republic of); Udintsev, Victor [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France)
2016-11-01
Highlights: • The cooling system of the ITER Generic Equatorial Port Plug (GEPP) is of a complicated combination of horizontal and vertical channels. • The calculation model for the entire GEPP cooling circuit comprising 12 sub-circuits and built up of 2421 finite-volume elements has been developed. • Transient analysis of this model simulating the draining procedure by the KORSAR/B1 code has been performed. • Water in amount of 263 g of initial 531 kg in the GEPP remains in the dead-ends of the DSM and DFW channels in 150 s of draining procedure. • Almost 3 h are required to boil off 263 g of water trapped in the dead-ends. - Abstract: For effective vacuum leak testing all cooling circuits serving the ITER vessel and in-vessel components shall be drained and dried so that after this procedure taking less than 100 h the purge gas passing through a component has water content less than 100 ppm. This process is four-stage, with the first stage using a short blast of compressed nitrogen to blow most of water in the coolant channels out of the circuit. This process is hindered by volumes which trap water due to gravity. To remove the trapped water, it is necessary, first, to heat up the structure by hot and compressed nitrogen, and then water is evaporated by depressurized nitrogen. The cooling system of the ITER Diagnostic Equatorial Port Plugs is of a complicated hydraulic configuration. The system branching might make difficult removal of water from the piping in the scheduled draining mode. The authors have proposed the KORSAR computation code to simulate draining of the GEPP cooling circuit. The numerical simulation performed has made it possible to describe the process dynamics during draining of the entire GEPP cooling circuit and to define the process time, amount and location of residual water and evolution of two-phase flow regime.
Numerical model and analysis of an energy-based system using microwaves for vision correction
Pertaub, Radha; Ryan, Thomas P.
2009-02-01
A treatment system was developed utilizing a microwave-based procedure capable of treating myopia and offering a less invasive alternative to laser vision correction without cutting the eye. Microwave thermal treatment elevates the temperature of the paracentral stroma of the cornea to create a predictable refractive change while preserving the epithelium and deeper structures of the eye. A pattern of shrinkage outside of the optical zone may be sufficient to flatten the central cornea. A numerical model was set up to investigate both the electromagnetic field and the resultant transient temperature distribution. A finite element model of the eye was created and the axisymmetric distribution of temperature calculated to characterize the combination of controlled power deposition combined with surface cooling to spare the epithelium, yet shrink the cornea, in a circularly symmetric fashion. The model variables included microwave power levels and pulse width, cooling timing, dielectric material and thickness, and electrode configuration and gap. Results showed that power is totally contained within the cornea and no significant temperature rise was found outside the anterior cornea, due to the near-field design of the applicator and limited thermal conduction with the short on-time. Target isothermal regions were plotted as a result of common energy parameters along with a variety of electrode shapes and sizes, which were compared. Dose plots showed the relationship between energy and target isothermic regions.
A joint-space numerical model of metabolic energy expenditure for human multibody dynamic system.
Kim, Joo H; Roberts, Dustyn
2015-09-01
Metabolic energy expenditure (MEE) is a critical performance measure of human motion. In this study, a general joint-space numerical model of MEE is derived by integrating the laws of thermodynamics and principles of multibody system dynamics, which can evaluate MEE without the limitations inherent in experimental measurements (phase delays, steady state and task restrictions, and limited range of motion) or muscle-space models (complexities and indeterminacies from excessive DOFs, contacts and wrapping interactions, and reliance on in vitro parameters). Muscle energetic components are mapped to the joint space, in which the MEE model is formulated. A constrained multi-objective optimization algorithm is established to estimate the model parameters from experimental walking data also used for initial validation. The joint-space parameters estimated directly from active subjects provide reliable MEE estimates with a mean absolute error of 3.6 ± 3.6% relative to validation values, which can be used to evaluate MEE for complex non-periodic tasks that may not be experimentally verifiable. This model also enables real-time calculations of instantaneous MEE rate as a function of time for transient evaluations. Although experimental measurements may not be completely replaced by model evaluations, predicted quantities can be used as strong complements to increase reliability of the results and yield unique insights for various applications. Copyright © 2015 John Wiley & Sons, Ltd.
Kumar, Sumeet; Heister, Stephen D.; Xu, Xianfan; Salvador, James R.; Meisner, Gregory P.
2013-04-01
A numerical model has been developed to simulate coupled thermal and electrical energy transfer processes in a thermoelectric generator (TEG) designed for automotive waste heat recovery systems. This model is capable of computing the overall heat transferred, the electrical power output, and the associated pressure drop for given inlet conditions of the exhaust gas and the available TEG volume. Multiple-filled skutterudites and conventional bismuth telluride are considered for thermoelectric modules (TEMs) for conversion of waste heat from exhaust into usable electrical power. Heat transfer between the hot exhaust gas and the hot side of the TEMs is enhanced with the use of a plate-fin heat exchanger integrated within the TEG and using liquid coolant on the cold side. The TEG is discretized along the exhaust flow direction using a finite-volume method. Each control volume is modeled as a thermal resistance network which consists of integrated submodels including a heat exchanger and a thermoelectric device. The pressure drop along the TEG is calculated using standard pressure loss correlations and viscous drag models. The model is validated to preserve global energy balances and is applied to analyze a prototype TEG with data provided by General Motors. Detailed results are provided for local and global heat transfer and electric power generation. In the companion paper, the model is then applied to consider various TEG topologies using skutterudite and bismuth telluride TEMs.
Lattice Integrable Systems of the Haldane-Shastry Type
Polychronakos, A P
1993-01-01
We present a new lattice integrable system in one dimension of the Haldane-Shastry type. It consists of spins positioned at the static equilibrium positions of particles in a corresponding classical Calogero system and interacting through an exchange term with strength inversely proportional to the square of their distance. We achieve this by viewing the Haldane-Shastry system as a high-interaction limit of the Sutherland system of particles with internal degrees of freedom and identifying the same limit in a corresponding Calogero system. The commuting integrals of motion of this system are found using the exchange operator formalism.
Fuel management of mixed reactor type power plant systems
International Nuclear Information System (INIS)
Csom, Gyula
1988-01-01
Breeding gain in symbiotic nuclear power plant system consisting of both thermal and fast breeder reactors depends on the characteristics and the ratio of thermal and fast reactors. The composition of the symbiotic power plant systems was determined for equilibrium and plutonium deficient systems. According to natural uranium utilization, symbiotic power plant systems are not less efficient than the systems containing only fast breeders. Depleted uranium can be applied in both types of systems. Reprocessing demands of the symbiotic power plant sytems were determined. (V.N.) 23 figs.; 1 tab
An Automatic Lab-on-Disc System for Blood Typing.
Chang, Yaw-Jen; Fan, Yi-Hua; Chen, Shia-Chung; Lee, Kuan-Hua; Lou, Liao-Yong
2018-04-01
A blood-typing assay is a critical test to ensure the serological compatibility of a donor and an intended recipient prior to a blood transfusion. This article presents a lab-on-disc blood-typing system to conduct a total of eight assays for a patient, including forward-typing tests, reverse-typing tests, and irregular-antibody tests. These assays are carried out in a microfluidic disc simultaneously. A blood-typing apparatus was designed to automatically manipulate the disc. The blood type can be determined by integrating the results of red blood cell (RBC) agglutination in the microchannels. The experimental results of our current 40 blood samples show that the results agree with those examined in the hospital. The accuracy reaches 97.5%.
DEFF Research Database (Denmark)
Zurkinden, Andrew Stephen; Kramer, Morten; Sichani, Mahdi Teimouri
2012-01-01
and the response of the device for regular and irregular waves were measured. Good correspondence is found between the numerical and the physical model for relatively mild wave conditions. For higher waves the numerical model seems to underestimate the response of the device due to its linear fluidstructure......Currently, a number of wave energy converters are being analyzed by means of numerical models in order to predict the electrical power generation under given wave conditions. A common characteristic of this procedure is to integrate the loadings from the hydrodynamics, power take-off and mooring...... systems into a central wave to wire model. The power production then depends on the control strategy which is applied to the device. The objective of this paper is to develop numerical methods for motion analysis of marine structures with a special emphasis on wave energy converters. Two different time...
International Nuclear Information System (INIS)
Herrera, J.V.; Garcia-Valladares, O.; Gomez, V.H.; Best, R.
2010-01-01
This paper describes the work made at the Centro de Investigacion en Energia in the development of an absorption refrigeration system for cooling and refrigeration applications with a capacity of 10 kW. The single effect unit utilizes ammonia-lithium nitrate as working pair and it is air cooled. The generator is a falling film type with horizontal tubes where the heating oil flows inside the tube bank and the ammonia-lithium nitrate solution flows as a falling film on the tube outside, where it is heated and ammonia vapor is generated. The generator consists of tree columns and four rows per column of horizontal tubes. The system was tested at controlled conditions with heating oil obtained from an electric resistance heating loop. A numerical model of the horizontal falling film generator was developed that divided the system into three different thermal elements: the flow inside the tube, the heat conduction in the tube wall and the falling film solution flow. The mathematical model was tested and validated with experimental data and a study of the influence of the heat transfer coefficient for ammonia-lithium nitrate solution in the numerical model was carried out. A comparison between experimental and numerical data for the heat flux in the system and the temperature profiles in the oil and solution flows shown a good degree of correlation.
Dong, Huaimin; Sun, Jianmeng; Lin, Zhenzhou; Fang, Hui; Li, Yafen; Cui, Likai; Yan, Weichao
2018-02-01
Natural gas hydrate is being considered as an alternative energy source for sustainable development and has become a focus of research throughout the world. In this paper, based on CT scanning images of hydrate reservoir rocks, combined with the microscopic distribution of hydrate, a diffusion limited aggregation (DLA) model was used to construct 3D hydrate digital rocks of different distribution types, and the finite-element method was used to simulate their electrical characteristics in order to study the influence of different hydrate distribution types, hydrate saturation and formation of water salinity on electrical properties. The results show that the hydrate digital rocks constructed using the DLA model can be used to characterize the microscopic distribution of different types of hydrates. Under the same conditions, the resistivity of the adhesive hydrate digital rock is higher than the cemented and scattered type digital rocks, and the resistivity of the scattered hydrate digital rock is the smallest among the three types. Besides, the difference in the resistivity of the different types of hydrate digital rocks increases with an increase in hydrate saturation, especially when the saturation is larger than 55%, and the rate of increase of each of the hydrate types is quite different. Similarly, the resistivity of the three hydrate types decreases with an increase in the formation of water salinity. The single distribution hydrate digital rock constructed, combined with the law of microscopic distribution and influence of saturation on the electrical properties, can effectively improve the accuracy of logging identification of hydrate reservoirs and is of great significance for the estimation of hydrate reserves.
3D Numerical Rift Modeling with Application to the East African Rift System
Glerum, A.; Brune, S.; Naliboff, J.
2017-12-01
As key components of plate tectonics, continental rifting and the formation of passive margins have been extensively studied with both analogue models and numerical techniques. Only recently however, technical advances have enabled numerical investigations into rift evolution in three dimensions, as is actually required for including those processes that cause rift-parallel variability, such as structural inheritance and oblique extension (Brune 2016). We use the massively parallel finite element code ASPECT (Kronbichler et al. 2012; Heister et al. 2017) to investigate rift evolution. ASPECT's adaptive mesh refinement enables us to focus resolution on the regions of interest (i.e. the rift center), while leaving other areas such as the asthenospheric mantle at coarse resolution, leading to kilometer-scale local mesh resolution in 3D. Furthermore, we implemented plastic and viscous strain weakening of the nonlinear viscoplastic rheology required to develop asymmetric rift geometries (e.g. Huismans and Beaumont 2003). Additionally created plugins to ASPECT allow us to specify initial temperature and composition conditions based on geophysical data (e.g. LITHO1.0, Pasyanos et al. 2014) or to prescribe more general along-strike variation in the initial strain seeding the rift. Employing the above functionality, we construct regional models of the East African Rift System (EARS), the world's largest currently active rift. As the EARS is characterized by both orthogonal and oblique rift sections, multi-phase extension histories as well as magmatic and a-magmatic branches (e.g. Chorowicz 2005; Ebinger and Scholz 2011), it constitutes an extensive natural laboratory for our research into the 3D nature of continental rifting. References:Brune, S. (2016), in Plate boundaries and natural hazards, AGU Geophysical Monograph 219, J. C. Duarte and W. P. Schellart (Eds.). Chorowicz, J. (2005). J. Afr. Earth Sci., 43, 379-410. Ebinger, C. and Scholz, C. A. (2011), in Tectonics of
Feed type based expert systems in mineral processing plants
International Nuclear Information System (INIS)
Jamsa-Jounela, S.-L.; Laine, S.; Laurila, H.
1999-01-01
Artificial Intelligence includes excellent tools for the control and supervision of industrial processes. Several thousand industrial applications have been reported worldwide. Recently, the designers of the AI systems have begun to hybridize the intelligent techniques, expert systems, fuzzy logic and neural networks, to enhance the capability of the AI systems. Expert systems have proved to be ideal candidates especially for the control of mineral processes. As successful case projects, expert system based on on-line classification of the feed type is described in this paper. The essential feature of this expert system is the classification of different feed types and their distinct control strategies at the plant. In addition to the classification, the expert system has a database containing information about how to handle the determined feed type. This self-learning database scans historical process data to suggest the best treatment for the ore type under processing. The system has been tested in two concentrators, the Outokumpu Finnmines Oy, Hitura mine and Outokumpu Chrome Oy, Kemi mine. (author)