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Simulation Program (simulation + program)
Selected AbstractsMODELING METALS TRANSPORT AND SEDIMENT/WATER INTERACTIONS IN A MINING IMPACTED MOUNTAIN STREAM,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 6 2004Brian S. Caruso ABSTRACT: The U.S. Environmental Protection Agency (USEPA) Water Quality Analysis Simulation Program (WASP5) was used to model the transport and sediment/water interactions of metals under low flow, steady state conditions in Tenmile Creek, a mountain stream supplying drinking water to the City of Helena, Montana, impacted by numerous abandoned hard rock mines. The model was calibrated for base flow using data collected by USEPA and validated using data from the U.S. Geological Survey (USGS) for higher flows. It was used to assess metals loadings and losses, exceedances of Montana State water quality standards, metals interactions in stream water and bed sediment, uncertainty in fate and transport processes and model parameters, and effectiveness of remedial alternatives that include leaving contaminated sediment in the stream. Results indicated that during base flow, adits and point sources contribute significant metals loadings to the stream, but that shallow ground water and bed sediment also contribute metals in some key locations. Losses from the water column occur in some areas, primarily due to adsorption and precipitation onto bed sediments. Some uncertainty exists in the metal partition coefficients associated with sediment, significance of precipitation reactions, and in the specific locations of unidentified sources and losses of metals. Standards exceedances are widespread throughout the stream, but the model showed that remediation of point sources and mine waste near water courses can help improve water quality. Model results also indicate, however, that alteration of the water supply scheme and increasing base flow will probably be required to meet all water quality standards. [source] Virtual reality simulations in Web-based science educationCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 1 2002Young-Suk Shin Abstract This article presents the educational possibilities of Web-based science education using a desktop virtual reality (VR) system. A Web site devoted to science education for middle school students has been designed and developed in the areas of earth sciences: meteorology, geophysics, geology, oceanography, and astronomy. Learners can establish by themselves the pace of their lessons using learning contents considered learner level and they can experiment in real time with the concepts they have learned, interacting with VR environments that we provide. A VR simulation program developed has been evaluated with a questionnaire from learners after learning freely on the Web. This study shows that Web-based science education using VR can be effectively used as a virtual class. When we consider the rapid development of VR technology and lowering of cost, the study can construct more immersive environments for the education in the near future. © 2002 Wiley Periodicals, Inc. Comput Appl Eng Educ 10: 18,25, 2002; Published online in Wiley InterScience (www.interscience.wiley.com.); DOI 10.1002/cae.10014 [source] Complex version of high performance computing LINPACK benchmark (HPL)CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 5 2010R. F. Barrett Abstract This paper describes our effort to enhance the performance of the AORSA fusion energy simulation program through the use of high-performance LINPACK (HPL) benchmark, commonly used in ranking the top 500 supercomputers. The algorithm used by HPL, enhanced by a set of tuning options, is more effective than that found in the ScaLAPACK library. Retrofitting these algorithms, such as look-ahead processing of pivot elements, into ScaLAPACK is considered as a major undertaking. Moreover, HPL is configured as a benchmark, but only for real-valued coefficients. We therefore developed software to convert HPL for use within an application program that generates complex coefficient linear systems. Although HPL is not normally perceived as a part of an application, our results show that the modified HPL software brings a significant increase in the performance of the solver when simulating the highest resolution experiments thus far configured, achieving 87.5 TFLOPS on over 20 000 processors on the Cray XT4. Copyright © 2009 John Wiley & Sons, Ltd. [source] Empirical prediction of debris-flow mobility and deposition on fansEARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2010Christian Scheidl Abstract A new method to predict the runout of debris flows is presented. A data base of documented sediment-transporting events in torrent catchments of Austria, Switzerland and northern Italy has been compiled, using common classification techniques. With this data we test an empirical approach between planimetric deposition area and event volume, and compare it with results from other studies. We introduce a new empirical relation to determine the mobility coefficient as a function of geomorphologic catchment parameters. The mobility coefficient is thought to reflect some of the flow properties during the depositional part of the debris-flow event. The empirical equations are implemented in a geographical information system (GIS) based simulation program and combined with a simple flow routing algorithm, to determine the potential runout area covered by debris-flow deposits. For a given volume and starting point of the deposits, a Monte-Carlo technique is used to produce flow paths that simulate the spreading effect of a debris flow. The runout zone is delineated by confining the simulated potential spreading area in the down slope direction with the empirically determined planimetric deposition area. The debris-flow volume is then distributed over the predicted area according to the calculated outflow probability of each cell. The simulation uses the ARC-Objects environment of ESRI© and is adapted to run with high resolution (2·5,m × 2·5,m) digital elevation models, generated for example from LiDAR data. The simulation program called TopRunDF is tested with debris-flow events of 1987 and 2005 in Switzerland. Copyright © 2009 John Wiley & Sons, Ltd. [source] Improvement of pulse pattern for space vector modulated matrix convertersELECTRICAL ENGINEERING IN JAPAN, Issue 1 2010Kichiro Yamamoto Abstract Novel modulation which consists of conventional space vector modulation (SVM) based on a virtual AC/DC/AC conversion and carrier signal modulation for matrix converters is proposed. In this proposed modulation, duties for the switching pattern decided by conventional SVM are changed into those for each switch of matrix converter. The new duties for each output phase are compared with the triangle carrier. By using proposed modulation, switchings between the input phase voltage with minimum value and the voltage with maximum value are eliminated. In this paper, the conventional SVM and proposed modulation are explained. Next, for both conventional and proposed modulations waveforms of input current, output voltage and output current and their frequency spectra are calculated by PSIM simulation program. Simulation results show the proposed modulation can reduce harmonics of output voltage waveforms. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(1): 46,54, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20903 [source] Fundamental characteristics and 3D electromagnetic analysis for magnetic levitation transporter using YBCO superconductorsELECTRICAL ENGINEERING IN JAPAN, Issue 2 2007Hiroshi Ueda Abstract A magnetic levitation device with two-dimensional movement, the so-called "levitating X-Y transporter," has been developed. In order to develop a working levitating X-Y transporter, it is necessary to clarify the levitation characteristics, such as the lift force, levitation height, and stability against mechanical disturbances. In this paper, we examine the lift and the restoring force experimentally and propose a new simulation program based on the three-dimensional hybrid finite and boundary element method to analyze the dynamic behavior of electromagnetic characteristics of YBCO bulk. Using the numerical simulation and experiments, we investigated a suitable arrangement of permanent magnets to enhance the levitation characteristics. We also designed a levitating transporter which can carry a load of 200 kg with a gap of 16 mm. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 44,54, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20220 [source] Behavior of interacting species in vacancy affinity capillary electrophoresis described by mass balance equationELECTROPHORESIS, Issue 16 2008Ying Sun Abstract Vacancy ACE (VACE) is one of the ACE methods, and has been used to study binding interactions between different biomolecules. Thermodynamic binding constants can be estimated with nonlinear regression methods. With a highly efficient computer simulation program (SimDCCE), it is possible to demonstrate the detailed behaviors of each species during the interaction process under different conditions. In this work, thirteen scenarios in four different combinations of migration orders of the free protein, free drug, and complex formed are studied. The detailed interaction process between protein and ligand is discussed and illustrated based on the mass balance equation, also called mass transfer equation. By properly setting the parameters in the simulation model, the influence of different factors during the interaction process can be well understood. [source] System zones in capillary zone electrophoresis: Moving boundaries caused by freely migrating hydrogen ionsELECTROPHORESIS, Issue 2 2005Jozef L. Beckers Abstract We demonstrate that system zones (SZs) can be expected in background electrolytes (BGEs) with a low buffer capacity. The mobilities of this type of SZ (mSZ) could be determined by calculations both based on a mathematical model and by a simulation program. The values of mSZ are increasing for decreasing buffer capacities and lower concentrations of the BGEs. For completely unbuffered BGEs with a pH below 7, the mSZ reached values up to 350×10,9 m2V,1s,1. This value indicates that the existence of this type of SZ originates from migrating hydrogen ions. Although both the mathematical model and simulation program do not consider the influence of the pH of the sample solution, experiments have shown that the pH of the sample solution is also very important. The lower the pH of the sample solution, the larger the mSZ in a specific BGE for cationic SZs. Using completely unbuffered BGEs the hydrogen ions present in the original sample start to migrate freely through the capillary tube with the mobility of a single hydrogen ion and cause stepwise disturbances in the base line of the detector trace. It is remarkable that this type of SZ appears not to affect the electromigration dispersion (EMD) in a strong way and so far only dips could be obtained experimentally. [source] Non-linear approaches for reducing large power systemsEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2001X. Lei Issues on the establishment of equivalent networks are becoming essential for the deregulated power market. This paper presents a comprehensive tool for network reduction of large power systems. Through integrating different methodologies into a simulation program, the dynamic equivalent can be established by adopting one common database. With a readily integrated modified Gauss-Newton algorithm, network reduction can be executed under the dynamic conditions either in the time domain or in the frequency domain in coping with nonlinear nature of the system involved. Furthermore, a novel algorithm based on dynamic coherency approach implemented readily into the simulation program is also presented. This novel approach determines coherent generators on non-linear basis in the time domain using the cross correlation technique, taking dynamic characteristics of the system involved into consideration. Two case studies are presented in this paper. Each of the non-linear approaches presented is applied for one of the case studies as application example. The results achieved validate the functionality of the approaches presented. [source] Improvement of interactions among facts controlsEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2000X. Lei Interaction among the FACTS (flexible AC transmission systems) devices in a multi-machine system can adversely influence the damping properties of individual FACTS devices. In some critical cases, it may even amplify power swings or increase voltage deviations. This paper presents a global tuning method for the FACTS controllers in a multi-machine system. Based on a non-linear optimization algorithm implemented in a simulation program, the parameter settings of the FACTS controllers involved can be simultaneously optimized at transient conditions in coping with the non-linear nature of the power system. By minimizing a non-explicit target function in which swing characteristics between areas are included, interactions among the FACTS controls at transient conditions in the multi-machine system are minimized. Two multi-machine power systems equipped individually with a TCSC (thyristor-controlled series compensator) and a SVC (static Var compensator) are applied to demonstrate the efficiency of the proposed tuning procedure. The results obtained from simulations validate the improvement in damping of overall power oscillations. The simulations also show that the optimized FACTS controllers are robust in providing adequate damping for a range of conditions on the system. [source] Fuel Cell Vehicle Simulation , Part 1: Benchmarking Available Fuel Cell Vehicle Simulation ToolsFUEL CELLS, Issue 3 2003K.H. Hauer Abstract Fuel cell vehicle simulation is one method for systematic and fast investigation of the different vehicle options (fuel choice, hybridization, reformer technologies). However, a sufficient modeling program, capable of modeling the different design options, is not available today. Modern simulation programs should be capable of serving as tools for analysis as well as development. Shortfalls of the existing programs, initially developed for internal combustion engine hybrid vehicles, are: (i)Insufficient modeling of transient characteristics; (ii) Insufficient modeling of the fuel cells system; (iii) Insufficient modeling of advanced hybrid systems; (iv) Employment of a non-causal (backwards looking) structure; (v) Significant shortcomings in the area of controls. In the area of analysis, a modeling tool for fuel cell vehicles needs to address the transient dynamic interaction between the electric drive train and the fuel cell system. Especially for vehicles with slow responding on-board fuel processor, this interaction is very different from the interaction between a battery (as power source) and an electric drive train in an electric vehicle design. Non-transient modeling leads to inaccurate predictions of vehicle performance and fuel consumption. When applied in the area of development, the existing programs do not support the employment of newer techniques, such as rapid prototyping. This is because the program structure merges control algorithms and component models, or different control algorithms (from different components) are lumped together in one single control block and not assigned to individual components as they are in real vehicles. In both cases, the transfer of control algorithms from the model into existing hardware is not possible. This paper is the first part of a three part series and benchmarks the "state of the art" of existing programs. The second paper introduces a new simulation program, which tries to overcome existing barriers. Specifically it explicitly recognizes the dynamic interaction between fuel cell system, drive train and optional additional energy storage. [source] Comparison of c-space and p-space particle tracing schemes on high-performance computers: accuracy and performanceINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2002F. Schäfer Abstract The present paper presents a comparison of four different particle tracing schemes which were integrated into a parallel multiblock flow simulation program within the frame of a co-visualization approach. One p-space and three different c-space particle tracing schemes are described in detail. With respect to application on high-performance computers, parallelization and vectorization of the particle tracing schemes are discussed. The accuracy and the performance of the particle tracing schemes are analyzed extensively on the basis of several test cases. The accuracy with respect to an analytically prescribed and a numerically calculated velocity field is investigated, the latter in order to take the contribution of the flow solver's error to the overall error of the particle traces into account. Performance measurements on both scalar and vector computers are discussed. With respect to practical CFD applications and the required performance especially on vector computers, a newly developed, improved c-space scheme is shown to be comparable to or better than the investigated p-space scheme. According to accuracy the new c-space scheme is considerably more advantageous than traditional c-space methods. Finally, an application to a direct numerical simulation of a turbulent channel flow is presented. Copyright © 2002 John Wiley & Sons, Ltd. [source] Universal resistorless current-mode filters employing CCCIIsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 5-6 2008Erkan Yuce Abstract In this paper, four different-type second-order current-mode filters, employing second-generation current-controlled conveyors (CCCIIs) and two capacitors, are proposed. The first two of the presented filters can simultaneously realize high-output impedance low-pass, band-pass and high-pass responses. Also, the two filters can provide notch and all-pass filter responses with interconnection of the relevant output currents. The first developed one needs no critical active and passive element matching conditions and/or cancellation constraints. The second and third introduced ones employ only grounded capacitors. The fourth proposed filter derived from the third one uses only plus-type single output CCCIIs (CCCII+s). The fifth filter can be constructed using commercially available active devices such as AD844s along with additional resistors instead of CCCII+s of the fourth proposed filter to perform experimental test easily. All of the proposed filters have low active and passive element sensitivities. Time and frequency domain analyses are performed for the first, second and third realized filters using SPICE simulation program. Also, experimental test is achieved for the fifth filter. In this study, stability problems attributed to non-ideal gains of the CCCIIs and signal limitations of the first, second and third introduced filters due to restricted power supply voltages are investigated. Copyright © 2007 John Wiley & Sons, Ltd. [source] Universal current-mode filters and parasitic impedance effects on the filter performancesINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 2 2008Erkan Yuce Abstract In this letter, two universal current-mode (CM) filters for simultaneously realizing low-pass, band-pass and high-pass characteristics are proposed. Both of the presented filters can also realize notch and all-pass responses with interconnection of the relevant output currents. They employ second-generation current-controlled conveyors (CCCIIs) and only grounded capacitors. They also have low active and passive element sensitivities along with electronically adjustable angular resonance frequency (,0) and quality factor (Q). Based on the first developed filter, the parasitic impedance effects of the conveyors on the filter performances are investigated in detail. Simulation results using SPICE simulation program are included to verify the theory. Copyright © 2007 John Wiley & Sons, Ltd. [source] Performance evaluation of an electricity base load engine cogeneration systemINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2010Denilson Boschiero do Espirito Santo Abstract Decentralized electricity production by cogeneration can result in primary energy economy, as these systems operate with a high-energy utilization factor (EUF), producing electricity and recovering energy rejected by the prime mover to meet site thermal demands. Because energy demands in buildings vary with such factors as the hour of the day, level of activity and climatic conditions, cogeneration case studies should consider different system configurations, energy demand profiles and climatic profiles. This paper analyzes an engine cogeneration system as an integrated thermal system by means of a computational simulation program. The simulation takes into account characteristics of the system, characteristics of the pieces of equipment, design choices and parameters, the variability of operating conditions, site energy demand profiles and climatic data to evaluate the performance of the cogeneration plant. Performance evaluation is based on: (i) the EUF, (ii) the exergy efficiency and (iii) primary energy savings analysis. Copyright © 2009 John Wiley & Sons, Ltd. [source] Implementation and evaluation of MPI-based parallel MD programINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2001R. Trobec Abstract The message-passing interface (MPI)-based object-oriented particle,particle interactions (PPI) library is implemented and evaluated. The library can be used in the n -particle simulation algorithm designed for a ring of p interconnected processors. The parallel simulation is scalable with the number of processors, and has the time requirement proportional to n2/p if n/p is large enough, which guarantees optimal speedup. In a certain range of problem sizes, the speedup becomes superlinear because enough cache memory is available in the system. The library is used in a simple way by any potential user, even with no deep programming knowledge. Different simulations using particles can be implemented on a wide spectrum of different computer platforms. The main purpose of this article is to test the PPI library on well-known methods, e.g., the parallel molecular dynamics (MD) simulation of the monoatomic system by the second-order leapfrog Verlet algorithm. The performances of the parallel simulation program implemented with the proposed library are competitive with a custom-designed simulation code. Also, the implementation of the split integration symplectic method, based on the analytical calculation of the harmonic part of the particle interactions, is shown, and its expected performances are predicted. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 84: 23,31, 2001 [source] Stimulating Simulations: Making the European Union a Classroom RealityINTERNATIONAL STUDIES PERSPECTIVES, Issue 2 2000Gretchen J. Van Dyke This article examines the organization and development of the Mid-Atlantic European Union Simulation Consortium (MEUSC), with special emphasis on linking theory to practice within its simulation program. The MEUSC program, initiated in 1993, brings fifteen colleges and universities to Washington, D.C., each December for an intercollegiate experiential learning exercise on the European Union. During the simulation, students meet with professional diplomats from both the United States and Europe, and they engage in consensus-building activities that mirror the decision-making processes of the EU Commission, Parliament, Council of Ministers, and the European Council. As a result, participants are able to refine and enhance a range of academic and practical skills that are keys for success in today's political and business worlds. The authors of this article make special use of a survey that was undertaken to gauge the impact of the simulation on its participants and, thus, its success as an educational venture. [source] Modeling and simulation of vehicle projection arrival,discharge process in adaptive traffic signal controlsJOURNAL OF ADVANCED TRANSPORTATION, Issue 3 2010Fang Clara Fang Abstract Real-time signal control operates as a function of the vehicular arrival and discharge process to satisfy a pre-specified operational performance. This process is often predicted based on loop detectors placed upstream of the signal. In our newly developed signal control for diamond interchanges, a microscopic model is proposed to estimate traffic flows at the stop-line. The model considers the traffic dynamics of vehicular detection, arrivals, and departures, by taking into account varying speeds, length of queues, and signal control. As the signal control is optimized over a rolling horizon that is divided into intervals, the vehicular detection for and projection into the corresponding horizon intervals are also modeled. The signal control algorithm is based on dynamic programming and the optimization of signal policy is performed using a certain performance measure involving delays, queue lengths, and queue storage ratios. The arrival,discharge model is embedded in the optimization algorithm and both are programmed into AIMSUN, a microscopic stochastic simulation program. AIMSUN is then used to simulate the traffic flow and implement the optimal signal control by accessing internal data including detected traffic demand and vehicle speeds. Sensitivity analysis is conducted to study the effect of selecting different optimization criteria on the signal control performance. It is concluded that the queue length and queue storage ratio are the most appropriate performance measures in real-time signal control of interchanges. Copyright © 2010 John Wiley & Sons, Ltd. [source] Teaching diffraction using computer simulations over the InternetJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2001Th. Proffen Computer simulations are a versatile tool to enhance the teaching of diffraction physics and related crystallographic topics to students of chemistry, materials science, physics and crystallography. Interactive computer simulations are presented, which have been added to a World Wide Web (WWW) based tutorial. A simple WWW interface is used to choose appropriate values for selected simulation parameters. The resulting structure and diffraction pattern are then plotted on the screen. Simulated structures range from a single atom to complex disordered or modulated structures. The simple interface requires no special computing knowledge and allows students to explore systematically the relationship between a real-space structure and the corresponding diffraction pattern. The large function set of the underlying simulation program (DISCUS) makes it easy to tailor the tutorial to a given syllabus by modifying or extending the current interactive examples. [source] CHARMM: The biomolecular simulation programJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 10 2009B. R. Brooks Abstract CHARMM (Chemistry at HARvard Molecular Mechanics) is a highly versatile and widely used molecular simulation program. It has been developed over the last three decades with a primary focus on molecules of biological interest, including proteins, peptides, lipids, nucleic acids, carbohydrates, and small molecule ligands, as they occur in solution, crystals, and membrane environments. For the study of such systems, the program provides a large suite of computational tools that include numerous conformational and path sampling methods, free energy estimators, molecular minimization, dynamics, and analysis techniques, and model-building capabilities. The CHARMM program is applicable to problems involving a much broader class of many-particle systems. Calculations with CHARMM can be performed using a number of different energy functions and models, from mixed quantum mechanical-molecular mechanical force fields, to all-atom classical potential energy functions with explicit solvent and various boundary conditions, to implicit solvent and membrane models. The program has been ported to numerous platforms in both serial and parallel architectures. This article provides an overview of the program as it exists today with an emphasis on developments since the publication of the original CHARMM article in 1983. © 2009 Wiley Periodicals, Inc.J Comput Chem, 2009. [source] Numerical analysis of polymer melt flow in the nipping regionPOLYMER ENGINEERING & SCIENCE, Issue 4 2002M. Takase In the extrusion coating process, it has never been revealed how a polymer melt flows near the nipping region and how the cooling process occurs. We created a numerical simulation program for the polymer melt flow near the nipping region using the finite element method. Numerical results showed the effects of many individual factors (e.g. line speed, melt thickness, extrusion temperature, shear-thinning property, etc.) on the cooling process and polymer melt flow near the nipping region. It was found that a polymer melt buildup that can be observed between two calender rolls in the sheet forming process also formed in the extrusion coating process, and that the amount of polymer melt buildup (bank) depended upon the coating condition. It was found that not only line speed and melt thickness contribute to the extrusion coating process significantly, but also the rheological property has an effect on the process. [source] Modelling of Shape Memory Alloys and Experimental VerificationPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003M. Schleich Prestrained shape memory alloys change their length when heated above their transformation temperature. This effect can be used to generate high forces in a small workspace, which has particular advantages in actuator design. The optimization and control of the shape memory actuator requires a comprehensive simulation of the material behavior. However, many of the existing models are limited to specific load cases or offer rough approximations only. A material model for shape memory alloys from Seelecke [1] is examined in this paper. This model describes the behavior of a shape memory wire, which is heated by electric current. It is implemented in a simulation program to investigate the actuator output and to improve the performance. Finally, the parameters of the simulation are adapted to experimental results. [source] High speed laser processing for monolithical series connection of silicon thin-film modulesPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 3 2008Stefan Haas Abstract A detailed analysis of the monolithical series connection of silicon thin-film modules with metal back contact fabricated by high-speed laser ablation will be presented. In this study, optically pumped solid-state lasers with wavelengths of 1064,nm and 532,nm were used for the patterning process. The influence of various laser parameters on the performance of amorphous and microcrystalline silicon modules will be discussed. In particular, the line-scribing parameters for a TCO and Ag back contact system was analyzed in detail, since it is the most critical patterning step. A detailed description of the back contact ablation process will be presented and a criterion for flakeless patterning was defined. Finally the influence of the back contact patterning on the electrical behavior of silicon single junction cells was studied. The dark current density versus back-contact patterning line length was analyzed by means of a developed SPICE (simulation program with integrated circuit emphasis) simulation model. Copyright © 2007 John Wiley & Sons, Ltd. [source] Schallfeldsimulation mit Spiegelquellen , Eine Planungshilfe für reflexionsarme RäumeBAUPHYSIK, Issue 4 2009Xueqin Zha Prof. Schall; Berechnungsverfahren; sound protection and acoustics; calculation methods Abstract Konventionelle Auslegungen von akustischen Freifeldräumen nach ISO 3745 sind häufig mit Risiken behaftet, weil die übliche Annahme eines Absorptionsgrades bei senkrechtem Schalleinfall von 99 % herkömmlicher faseriger oder poröser Auskleidungen von Fall zu Fall weder notwendig noch ausreichend sein kann. Es wird ein Simulationsprogramm vorgestellt, das mit der phasenrichtigen Überlagerung der Schallwellen einer realen Punkt- und einer Serie von Spiegelquellen arbeitet, welche die unvollständig absorbierenden Begrenzungsflächen des Raumes ersetzen. Damit werden verschiedene Einflüsse aufgezeigt, die die Freifeldeigenschaften ebenso stark beeinflussen können wie der Absorptionsgrad der Auskleidung. So lässt sich bereits in einem frühen Planungsstadium mehr Sicherheit über die Qualität eines Akustik-Prüfstandes zur Bestimmung von Schallleistung, Spektrum und Richtcharakteristik technischer Schallquellen gewinnen. Sound field simulation by image sources , A design tool for anechoic rooms. Conventional designs of anechoic rooms according to ISO 3745 often bear risks since the usual assumption of an absorption coefficient at normal incidence of 99 % of traditional fibrous or porous claddings may be not necessary in one case but insufficient in another. A simulation program is presented which is based on the wave interferences of the sound from a real point source and a number of image sources which replace imperfectly absorbing bounding surfaces. Its application demonstrates various effects which can influence the free-field characteristics to the same extent as the absorption of the cladding. By this one may gain more confidence , at an early stage of the planning process , in the quality of an acoustic test facility for the determination of sound power, spectrum and directivity of technical sound sources. [source] Improving Thai students' understanding of concepts in protein purification by using Thai and English versions of a simulation program,BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 5 2007Somkiat Phornphisutthimas Abstract To support student learning in biochemistry and related courses, a simulation program, the Protein Purification Program, offers an alternative multimedia-based tool. This program has now been translated to produce a Thai version. However, translation from the original into the Thai language is limited by the differences between the language characteristics of English and Thai. Therefore, use of the program with Thai students had a twofold purpose. It helped their understanding of the concepts of protein purification by allowing code switching between the languages, but it also improved their understanding of, and competence in scientific English, which is a vital skill for functioning as a modern biochemist. According to the results of the questionnaires, undergraduates using the Thai/English program scored significantly higher than those using only the English language program (p < 0.05). In addition, the interview data suggested that the Thai/English program had improved student understanding of the concepts of protein purification to a greater extent than a single language (English) program. Students' overall preference in terms of their learning using the Thai/English program was 4.15 on a 1,5 Likert scale. [source] Kinetics of lactose hydrolysis by ,-galactosidase of Kluyveromyces lactis immobilized on cotton fabricBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2003Quinn Zhengkun Zhou Abstract A mathematic model for describing the Michaelis-Menten-type reaction kinetics with product competitive inhibition and side-reaction is proposed. A multiresponse nonlinear simulation program was employed to determine the coefficients of a four-parameter rate expression. The rate expression was compared with the conventional Michaelis-Menten reaction rate models with and without product inhibition. Experimental data were obtained using ,-galactosidase of Kluyveromyces lactis immobilized on cotton fabric in a batch system at a temperature of 37°C and at various initial concentrations of dissolved lactose ranging from 3,12.5% (w/v). The reaction is followed by concentration changes with time in the tank. Samples were obtained after the outlet stream of the packed bed reactor is mixed in a well-stirred tank. High-performance liquid chromatography (HPLC) was applied to monitor the concentrations of all the sugars (reactants as well as products). The four-parameter rate model is featured with a term to describe the formation of trisaccharides, a side-reaction of the enzymatic hydrolysis. The proposed model simulates the process of lactose hydrolysis and the formation of glucose and galactose, giving better accuracy compared with the previous models. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 127,133, 2003. [source] Computer-assisted dosage calculation for strabismus therapy in myopic patientsACTA OPHTHALMOLOGICA, Issue 1 2008Martina Koch Abstract. Purpose:, The published dosage recommendations for the surgical correction of horizontal strabismus in non-myopic patients show large, unexplained differences. For patients with high myopia, the situation becomes even more complex because the increase in the size of the bulb also affects the geometry of the oculomotor muscles. In this study, we wanted to investigate whether computer simulations of the oculomotor plant can be used to find accurate surgical parameters. Methods:, In a retrospective study, we investigated pre- and postoperative strabismus patterns in 13 patients affected by convergent (seven patients) or divergent (six patients) strabismus and high myopia. Postoperative checks were made 1 day, 1 week, 3 months and 1,6 years after the operation. For each patient, we simulated the presurgical strabismus pattern with SEE++ (see ,Further Information' for manufacturer details), a biomechanical simulation program of the oculomotor plant. The individual results of the simulations were then compared to the measured postoperative strabismus patterns. Results:, We found a trend of under-correction in the postoperative situation, resulting in four patients having a large remaining strabismus angle of more than 5 degrees. The computer simulations were able to reproduce this under-correction, and suggested an increase in dosage. Conclusion:, We conclude that realistic biomechanical simulations of the oculomotor plant can predict the postoperative result for myopic patients accurately. The results of the computer simulation correlate well with the postoperative outcome of the patient. [source] Fuel Cell Vehicle Simulation , Part 1: Benchmarking Available Fuel Cell Vehicle Simulation ToolsFUEL CELLS, Issue 3 2003K.H. Hauer Abstract Fuel cell vehicle simulation is one method for systematic and fast investigation of the different vehicle options (fuel choice, hybridization, reformer technologies). However, a sufficient modeling program, capable of modeling the different design options, is not available today. Modern simulation programs should be capable of serving as tools for analysis as well as development. Shortfalls of the existing programs, initially developed for internal combustion engine hybrid vehicles, are: (i)Insufficient modeling of transient characteristics; (ii) Insufficient modeling of the fuel cells system; (iii) Insufficient modeling of advanced hybrid systems; (iv) Employment of a non-causal (backwards looking) structure; (v) Significant shortcomings in the area of controls. In the area of analysis, a modeling tool for fuel cell vehicles needs to address the transient dynamic interaction between the electric drive train and the fuel cell system. Especially for vehicles with slow responding on-board fuel processor, this interaction is very different from the interaction between a battery (as power source) and an electric drive train in an electric vehicle design. Non-transient modeling leads to inaccurate predictions of vehicle performance and fuel consumption. When applied in the area of development, the existing programs do not support the employment of newer techniques, such as rapid prototyping. This is because the program structure merges control algorithms and component models, or different control algorithms (from different components) are lumped together in one single control block and not assigned to individual components as they are in real vehicles. In both cases, the transfer of control algorithms from the model into existing hardware is not possible. This paper is the first part of a three part series and benchmarks the "state of the art" of existing programs. The second paper introduces a new simulation program, which tries to overcome existing barriers. Specifically it explicitly recognizes the dynamic interaction between fuel cell system, drive train and optional additional energy storage. [source] An air filter pressure loss model for fan energy calculation in air handling unitsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 6 2003Mingsheng Liu Abstract Air filters consume a significant part of the fan power in air handling systems. Due to lack of suitable models, the fan energy associated with the filter pressure drop is often estimated based on average airflow and average pressure drop across the filter. Since the pressure drop varies nonlinearly with airflow and the filter resistance varies with dirt build-up, current methods often produce erroneous results. This paper presents a new air filter pressure loss model that has been developed and verified using experimental data. The model projects the pressure losses across the filter for both constant and variable airflows. The inputs to the model are the airflow rate, the time of use, the initial design and final pressure losses at the design flow rate, and the coefficient of a power law regression of pressure loss as a function of airflow rate. The air filter pressure loss model may be implemented in hourly building energy simulation programs that perform hourly simulation at the air handling unit level. Copyright © 2003 John Wiley & Sons, Ltd. [source] Enabling a compact model to simulate the RF behavior of MOSFETs in SPICEINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2005Reydezel Torres-Torres Abstract A detailed methodology for implementing a MOSFET model valid to perform RF simulations is described in this article. Since the SPICE-like simulation programs are used as a standard tool for integrated circuit (IC) design, the resulting model is oriented for its application under the SPICE environment. The core of the proposed model is the popular BSIM3v3, but in this model the RF effects are taken into account by means of extrinsic lumped elements. Good agreement between the simulated and measured small-signal S -parameter data is achieved for a 0.18-,m channel-length MOSFET, thus validating the proposed model. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE 15, 2005. [source] | ||||||||||||||||||||||