WorldWideScience

Sample records for hybrid qualitative simulation

  1. Business Scenario Evaluation Method Using Monte Carlo Simulation on Qualitative and Quantitative Hybrid Model

    Science.gov (United States)

    Samejima, Masaki; Akiyoshi, Masanori; Mitsukuni, Koshichiro; Komoda, Norihisa

    We propose a business scenario evaluation method using qualitative and quantitative hybrid model. In order to evaluate business factors with qualitative causal relations, we introduce statistical values based on propagation and combination of effects of business factors by Monte Carlo simulation. In propagating an effect, we divide a range of each factor by landmarks and decide an effect to a destination node based on the divided ranges. In combining effects, we decide an effect of each arc using contribution degree and sum all effects. Through applied results to practical models, it is confirmed that there are no differences between results obtained by quantitative relations and results obtained by the proposed method at the risk rate of 5%.

  2. A Finding Method of Business Risk Factors Using Characteristics of Probability Distributions of Effect Ratios on Qualitative and Quantitative Hybrid Simulation

    Science.gov (United States)

    Samejima, Masaki; Negoro, Keisuke; Mitsukuni, Koshichiro; Akiyoshi, Masanori

    We propose a finding method of business risk factors on qualitative and quantitative hybrid simulation in time series. Effect ratios of qualitative arcs in the hybrid simulation vary output values of the simulation, so we define effect ratios causing risk as business risk factors. Finding business risk factors in entire ranges of effect ratios is time-consuming. It is considered that probability distributions of effect ratios in present time step and ones in previous time step are similar, the probability distributions in present time step can be estimated. Our method finds business risk factors in only estimated ranges effectively. Experimental results show that a precision rate and a recall rate are 86%, and search time is decreased 20% at least.

  3. Electric/Hybrid Vehicle Simulation

    Science.gov (United States)

    Slusser, R. A.; Chapman, C. P.; Brennand, J. P.

    1985-01-01

    ELVEC computer program provides vehicle designer with simulation tool for detailed studies of electric and hybrid vehicle performance and cost. ELVEC simulates performance of user-specified electric or hybrid vehicle under user specified driving schedule profile or operating schedule. ELVEC performs vehicle design and life cycle cost analysis.

  4. Hybrid Simulation of Composite Structures

    DEFF Research Database (Denmark)

    Høgh, Jacob Herold

    Hybrid simulation is a substructural method combining a numerical simulation with a physical experiment. A structure is thereby simulated under the assumption that a substructure’s response is well known and easily modelled while a given substructure is studied more accurately in a physical...... of freedom. In this dissertation the main focus is to develop hybrid simulation for composite structures e.g. wind turbine blades where the boundary between the numerical model and the physical experiment is continues i.e. in principal infinite amount of degrees of freedom. This highly complicates...

  5. Reasoning about energy in qualitative simulation

    Science.gov (United States)

    Fouche, Pierre; Kuipers, Benjamin J.

    1992-01-01

    While possible behaviors of a mechanism that are consistent with an incomplete state of knowledge can be predicted through qualitative modeling and simulation, spurious behaviors corresponding to no solution of any ordinary differential equation consistent with the model may be generated. The present method for energy-related reasoning eliminates an important source of spurious behaviors, as demonstrated by its application to a nonlinear, proportional-integral controlled. It is shown that such qualitative properties of such a system as stability and zero-offset control are captured by the simulation.

  6. Analysis of hybrid viscous damper by real time hybrid simulations

    DEFF Research Database (Denmark)

    Brodersen, Mark Laier; Ou, Ge; Høgsberg, Jan Becker

    2016-01-01

    Results from real time hybrid simulations are compared to full numerical simulations for a hybrid viscous damper, composed of a viscous dashpot in series with an active actuator and a load cell. By controlling the actuator displacement via filtered integral force feedback the damping performance...... of the hybrid viscous damper is improved, while for pure integral force feedback the damper stroke is instead increased. In the real time hybrid simulations viscous damping is emulated by a bang-bang controlled Magneto-Rheological (MR) damper. The controller activates high-frequency modes and generates drift...... in the actuator displacement, and only a fraction of the measured damper force can therefore be used as input to the investigated integral force feedback in the real time hybrid simulations....

  7. Hybrid2 - The hybrid power system simulation model

    Energy Technology Data Exchange (ETDEWEB)

    Baring-Gould, E.I.; Green, H.J.; Dijk, V.A.P. van [National Renewable Energy Lab., Golden, CO (United States); Manwell, J.F. [Univ. of Massachusetts, Amherst, MA (United States)

    1996-12-31

    There is a large-scale need and desire for energy in remote communities, especially in the developing world; however the lack of a user friendly, flexible performance prediction model for hybrid power systems incorporating renewables hindered the analysis of hybrids as options to conventional solutions. A user friendly model was needed with the versatility to simulate the many system locations, widely varying hardware configurations, and differing control options for potential hybrid power systems. To meet these ends, researchers from the National Renewable Energy Laboratory (NREL) and the University of Massachusetts (UMass) developed the Hybrid2 software. This paper provides an overview of the capabilities, features, and functionality of the Hybrid2 code, discusses its validation and future plans. Model availability and technical support provided to Hybrid2 users are also discussed. 12 refs., 3 figs., 4 tabs.

  8. Simulation of a Hybrid Locomotion Robot Vehicle

    Science.gov (United States)

    Aarnio, P.

    2002-10-01

    This study describes a simulation process of a mobile robot. The focus is in kinematic and dynamic behavior simulations of hybrid locomotion robot vehicles. This research is motivated by the development needs of the WorkPartner field service robot. The whole robot system consists of a mobile platform and a two-hand manipulator. The robot platform, called Hybtor, is a hybrid locomotion robot capable of walking and driving by wheels as well as combining these two locomotion modes. This study describes first the general problems and their solutions in the dynamic simulation of mobile robots. A kinematic and dynamic virtual model of the Hybtor robot was built and simulations were carried out using one commercial simulation tool. Walking, wheel driven and rolking mode locomotion, which is a special hybrid locomotion style, has been simulated and analyzed. Position and force control issues during obstacle overrun and climbing were also studied.

  9. Hybrid simulation models of production networks

    CERN Document Server

    Kouikoglou, Vassilis S

    2001-01-01

    This book is concerned with a most important area of industrial production, that of analysis and optimization of production lines and networks using discrete-event models and simulation. The book introduces a novel approach that combines analytic models and discrete-event simulation. Unlike conventional piece-by-piece simulation, this method observes a reduced number of events between which the evolution of the system is tracked analytically. Using this hybrid approach, several models are developed for the analysis of production lines and networks. The hybrid approach combines speed and accuracy for exceptional analysis of most practical situations. A number of optimization problems, involving buffer design, workforce planning, and production control, are solved through the use of hybrid models.

  10. Methane production in simulated hybrid bioreactor landfill.

    Science.gov (United States)

    Xu, Qiyong; Jin, Xiao; Ma, Zeyu; Tao, Huchun; Ko, Jae Hac

    2014-09-01

    The aim of this work was to study a hybrid bioreactor landfill technology for landfill methane production from municipal solid waste. Two laboratory-scale columns were operated for about ten months to simulate an anaerobic and a hybrid landfill bioreactor, respectively. Leachate was recirculated into each column but aeration was conducted in the hybrid bioreactor during the first stage. Results showed that leachate pH in the anaerobic bioreactor maintained below 6.5, while in the hybrid bioreactor quickly increased from 5.6 to 7.0 due to the aeration. The temporary aeration resulted in lowering COD and BOD5 in the leachate. The volume of methane collected from the hybrid bioreactor was 400 times greater than that of the anaerobic bioreactor. Also, the methane production rate of the hybrid bioreactor was improved within a short period of time. After about 10 months' operation, the total methane production in the hybrid bioreactor was 212 L (16 L/kgwaste).

  11. TRNSYS HYBRID wind diesel PV simulator

    Energy Technology Data Exchange (ETDEWEB)

    Quinlan, P.J.A.; Mitchell, J.W.; Klein, S.A.; Beckman, W.A.; Blair, N.J. [Univ. of Wisconsin, Madison, WI (United States)

    1996-12-31

    The Solar Energy Laboratory (SEL) has developed a wind diesel PV hybrid systems simulator, UW-HYBRID 1.0, an application of the TRNSYS 14.2 time-series simulation environment. An AC/DC bus links up to five diesels and wind turbine models, along with PV modules, a battery bank, and an AC/DC converter. Multiple units can be selected. PV system simulations include solar angle and peak power tracking options. Weather data are Typical Meteorological Year data, parametrically generated synthesized data, or external data files. PV performance simulations rely on long-standing SEL-developed algorithms. Loads data are read as scalable time series. Diesel simulations include estimated fuel-use and waste heat output, and are dispatched using a least-cost of fuel strategy. Wind system simulations include varying air density, wind shear and wake effects. Time step duration is user-selectable. UW-HYBRID 1.0 runs in Windows{reg_sign}, with TRNSED providing a customizable user interface. 12 refs., 6 figs.

  12. Qualitative and Quantitative Integrated Modeling for Stochastic Simulation and Optimization

    Directory of Open Access Journals (Sweden)

    Xuefeng Yan

    2013-01-01

    Full Text Available The simulation and optimization of an actual physics system are usually constructed based on the stochastic models, which have both qualitative and quantitative characteristics inherently. Most modeling specifications and frameworks find it difficult to describe the qualitative model directly. In order to deal with the expert knowledge, uncertain reasoning, and other qualitative information, a qualitative and quantitative combined modeling specification was proposed based on a hierarchical model structure framework. The new modeling approach is based on a hierarchical model structure which includes the meta-meta model, the meta-model and the high-level model. A description logic system is defined for formal definition and verification of the new modeling specification. A stochastic defense simulation was developed to illustrate how to model the system and optimize the result. The result shows that the proposed method can describe the complex system more comprehensively, and the survival probability of the target is higher by introducing qualitative models into quantitative simulation.

  13. Recent qualitative advances on hybrid organizations: taking stock, looking ahead

    NARCIS (Netherlands)

    Jolink, A.; Niesten, E.M.M.I.

    2012-01-01

    Where does the study of hybrids stand at present? Through a review of existing research, this paper provides a number of contributions to the literature on inter-organizational relations, or hybrids. For one, basing ourselves on the traditional theories used in the study of hybrids, we propose an in

  14. Hybrid Method Simulation of Slender Marine Structures

    DEFF Research Database (Denmark)

    Christiansen, Niels Hørbye

    This present thesis consists of an extended summary and five appended papers concerning various aspects of the implementation of a hybrid method which combines classical simulation methods and artificial neural networks. The thesis covers three main topics. Common for all these topics...... is that they deal with time domain simulation of slender marine structures such as mooring lines and flexible risers used in deep sea offshore installations. The first part of the thesis describes how neural networks can be designed and trained to cover a large number of different sea states. Neural networks can...... that a single neural network can cover all relevant sea states. The applicability and performance of the present hybrid method is demonstrated on a numerical model of a mooring line attached to a floating offshore platform. The second part of the thesis demonstrates how sequential neural networks can be used...

  15. Causes of Ineradicable Spurious Predictions in Qualitative Simulation

    CERN Document Server

    Say, A C Cem; 10.1613/jair.2065

    2011-01-01

    It was recently proved that a sound and complete qualitative simulator does not exist, that is, as long as the input-output vocabulary of the state-of-the-art QSIM algorithm is used, there will always be input models which cause any simulator with a coverage guarantee to make spurious predictions in its output. In this paper, we examine whether a meaningfully expressive restriction of this vocabulary is possible so that one can build a simulator with both the soundness and completeness properties. We prove several negative results: All sound qualitative simulators, employing subsets of the QSIM representation which retain the operating region transition feature, and support at least the addition and constancy constraints, are shown to be inherently incomplete. Even when the simulations are restricted to run in a single operating region, a constraint vocabulary containing just the addition, constancy, derivative, and multiplication relations makes the construction of sound and complete qualitative simulators i...

  16. A Dynamical Simulation Facility for Hybrid Systems

    CERN Document Server

    Back, A; Myers, M; Back, Allen; Guckenheimer, John; Myers, Mark

    1993-01-01

    Abstract: This paper establishes a general framework for describing hybrid dynamical systems which is particularly suitable for numerical simulation. In this context, the data structures used to describe the sets and functions which comprise the dynamical system are crucial since they provide the link between a natural mathematical formulation of a problem and the correct application of standard numerical algorithms. We describe a partial implementation of the design methodology and use this simulation tool for a specific control problem in robotics as an illustration of the utility of the approach for practical applications.

  17. CONCEPTUAL MECHANICAL DESIGN METHOD BASED ON QUALITATIVE SIMULATION

    Institute of Scientific and Technical Information of China (English)

    Yang Jianming; Yang Ping; Zou Bailong; Yang Chengsan

    2005-01-01

    A model for conceptual design of mechanical devices is studied based on qualitative simulation. In this model, the desired functions are expressed by state-transit-diagrams(ST-diagrams)and design space is represented by qualitative-state-curves(QS-curves). The first design idea, called seeds idea, is proposed by the designer and then is abstracted into QS-curves. The qualitative simulation is implemented based on the QS-curves. By changing the motion of acting parts, the connection of parts and the motion of driving part, new design ideas are generated. With this model, a series of new design ideas derived from the seeds idea can be achieved.

  18. CONFIG - Adapting qualitative modeling and discrete event simulation for design of fault management systems

    Science.gov (United States)

    Malin, Jane T.; Basham, Bryan D.

    1989-01-01

    CONFIG is a modeling and simulation tool prototype for analyzing the normal and faulty qualitative behaviors of engineered systems. Qualitative modeling and discrete-event simulation have been adapted and integrated, to support early development, during system design, of software and procedures for management of failures, especially in diagnostic expert systems. Qualitative component models are defined in terms of normal and faulty modes and processes, which are defined by invocation statements and effect statements with time delays. System models are constructed graphically by using instances of components and relations from object-oriented hierarchical model libraries. Extension and reuse of CONFIG models and analysis capabilities in hybrid rule- and model-based expert fault-management support systems are discussed.

  19. A Qualitative Experiment: Research on Mediated Meaning Construction Using a Hybrid Approach

    Science.gov (United States)

    Robinson, Sue; Mendelson, Andrew L.

    2012-01-01

    This article presents a hybrid methodological technique that fuses elements of experimental design with qualitative strategies to explore mediated communication. Called the "qualitative experiment," this strategy uses focus groups and in-depth interviews "within" randomized stimulus conditions typically associated with…

  20. Developing integrated patient pathways using hybrid simulation

    Science.gov (United States)

    Zulkepli, Jafri; Eldabi, Tillal

    2016-10-01

    Integrated patient pathways includes several departments, i.e. healthcare which includes emergency care and inpatient ward; intermediate care which patient(s) will stay for a maximum of two weeks and at the same time be assessed by assessment team to find the most suitable care; and social care. The reason behind introducing the intermediate care in western countries was to reduce the rate of patients that stays in the hospital especially for elderly patients. This type of care setting has been considered to be set up in some other countries including Malaysia. Therefore, to assess the advantages of introducing this type of integrated healthcare setting, we suggest develop the model using simulation technique. We argue that single simulation technique is not viable enough to represent this type of patient pathways. Therefore, we suggest develop this model using hybrid techniques, i.e. System Dynamics (SD) and Discrete Event Simulation (DES). Based on hybrid model result, we argued that the result is viable to be as references for decision making process.

  1. Hybrid Simulations of Particle Acceleration at Shocks

    CERN Document Server

    Caprioli, Damiano

    2014-01-01

    We present the results of large hybrid (kinetic ions - fluid electrons) simulations of particle acceleration at non-relativistic collisionless shocks. Ion acceleration efficiency and magnetic field amplification are investigated in detail as a function of shock inclination and strength, and compared with predictions of diffusive shock acceleration theory, for shocks with Mach number up to 100. Moreover, we discuss the relative importance of resonant and Bell's instability in the shock precursor, and show that diffusion in the self-generated turbulence can be effectively parametrized as Bohm diffusion in the amplified magnetic field.

  2. Cluster hybrid Monte Carlo simulation algorithms

    Science.gov (United States)

    Plascak, J. A.; Ferrenberg, Alan M.; Landau, D. P.

    2002-06-01

    We show that addition of Metropolis single spin flips to the Wolff cluster-flipping Monte Carlo procedure leads to a dramatic increase in performance for the spin-1/2 Ising model. We also show that adding Wolff cluster flipping to the Metropolis or heat bath algorithms in systems where just cluster flipping is not immediately obvious (such as the spin-3/2 Ising model) can substantially reduce the statistical errors of the simulations. A further advantage of these methods is that systematic errors introduced by the use of imperfect random-number generation may be largely healed by hybridizing single spin flips with cluster flipping.

  3. Qualitative vs. quantitative software process simulation modelling: conversion and comparison

    OpenAIRE

    Zhang, He; Kitchenham, Barbara; Jeffery, Ross

    2009-01-01

    peer-reviewed Software Process Simulation Modeling (SPSM) research has increased in the past two decades. However, most of these models are quantitative, which require detailed understanding and accurate measurement. As the continuous work to our previous studies in qualitative modeling of software process, this paper aims to investigate the structure equivalence and model conversion between quantitative and qualitative process modeling, and to compare the characteristics and performance o...

  4. Hybrid Simulations of Pluto's Plasma Interaction

    Science.gov (United States)

    Feyerabend, M.; Simon, S.; Motschmann, U.; Liuzzo, L.

    2016-12-01

    We study the interaction between Pluto and the solar wind at the time of the New Horizons (NH) flyby by applying a hybrid (kinetic ions, fluid electrons) simulation model. The use of a hybrid model is necessary since the gyroradii of the involved ion species are more than an order of magnitude larger than the obstacle to the solar wind and thus, Pluto's interaction region displays considerable asymmetries. We investigate the three-dimensional structure and extension of the various plasma signatures seen along the NH trajectory. Especially, we will constrain possible asymmetries in the shape of Pluto's bow shock, plasma tail and Plutopause (i.e., the boundary between the solar wind and the population of plutogenic ions) which may arise from the large ion gyroradii. Starting from the upstream solar wind parameters measured by NH, we investigate the dependency of these plasma signatures on the density of Pluto's ionosphere and on the solar wind ram pressure. We also include Pluto's largest moon Charon into the simulation model and study the simultaneous interaction between both bodies and the solar wind. Data from NH suggest that Charon mainly acts as a plasma absorber without an appreciable atmosphere. For various relative positions of Pluto and Charon, we investigate the deformation of Charon's wake when exposed to the inhomogeneous plasma flow in the Pluto interaction region, as well as a possible feedback of Charon on the structure of Pluto's induced magnetosphere.

  5. Hybrid simulations of mini-magnetospheres in the laboratory

    CERN Document Server

    Gargaté, L; Fonseca, R A; Bamford, R; Thornton, A; Gibson, K; Bradford, J; Silva, L O

    2008-01-01

    Solar energetic ions are a known hazard to both spacecraft electronics and to manned space flights in interplanetary space missions that extend over a long period of time. A dipole-like magnetic field and a plasma source, forming a mini magnetosphere, are being tested in the laboratory as means of protection against such hazards. We investigate, via particle-in-cell hybrid simulations, using kinetic ions and fluid electrons, the characteristics of the mini magnetospheres. Our results, for parameters identical to the experimental conditions, reveal the formation of a mini-magnetosphere, whose features are scanned with respect to the plasma density, the plasma flow velocity, and the intensity of the dipole field. Comparisons with a simplified theoretical model reveal a good qualitative agreement and excellent quantitative agreement for higher plasma dynamic pressures and lower B-fields.

  6. Accelerating Climate Simulations Through Hybrid Computing

    Science.gov (United States)

    Zhou, Shujia; Sinno, Scott; Cruz, Carlos; Purcell, Mark

    2009-01-01

    Unconventional multi-core processors (e.g., IBM Cell B/E and NYIDIDA GPU) have emerged as accelerators in climate simulation. However, climate models typically run on parallel computers with conventional processors (e.g., Intel and AMD) using MPI. Connecting accelerators to this architecture efficiently and easily becomes a critical issue. When using MPI for connection, we identified two challenges: (1) identical MPI implementation is required in both systems, and; (2) existing MPI code must be modified to accommodate the accelerators. In response, we have extended and deployed IBM Dynamic Application Virtualization (DAV) in a hybrid computing prototype system (one blade with two Intel quad-core processors, two IBM QS22 Cell blades, connected with Infiniband), allowing for seamlessly offloading compute-intensive functions to remote, heterogeneous accelerators in a scalable, load-balanced manner. Currently, a climate solar radiation model running with multiple MPI processes has been offloaded to multiple Cell blades with approx.10% network overhead.

  7. Hybrid simulation: an active power filter case study

    Directory of Open Access Journals (Sweden)

    Y. A. Garcés

    2011-10-01

    Full Text Available The hybrid simulation concept consisting of a combination of computer simulation and laboratory tests. This approach is a cost effective alternative to physically testing the whole system and allows better understanding of complex coupled systems.This paper describes implementing an active power filter (APF hybrid prototype where the source system and load are implemented as a real-time simulation and the system of static power converter acting as an active power filter is implemented in physical hardware. It also confirmed the hybrid simulation results by implementing the simulation in MATLAB-Simulink regarding the same system implemented during the active power filter analysis and design stage.

  8. Little qualitative RNA misexpression in sterile male F1 hybrids of Drosophila pseudoobscura and D. persimilis

    Directory of Open Access Journals (Sweden)

    Noor Mohamed AF

    2002-09-01

    Full Text Available Abstract Background Although the genetics of hybrid sterility has been the subject of evolutionary studies for over sixty years, no one has shown the reason(s why alleles that operate normally within species fail to function in another genetic background. Several lines of evidence suggest that failures in normal gene transcription contribute to hybrid dysfunctions, but genome-wide studies of gene expression in pure-species and hybrids have not been undertaken. Here, we study genome-wide patterns of expression in Drosophila pseudoobscura, D. persimilis, and their sterile F1 hybrid males using differential display. Results Over five thousand amplifications were analyzed, and 3312 were present in amplifications from both of the pure species. Of these, 28 (0.5% were not present in amplifications from adult F1 hybrid males. Using product-specific primers, we were able to confirm one of nine of the transcripts putatively misexpressed in hybrids. This transcript was shown to be male-specific, but without detectable homology to D. melanogaster sequence. Conclusion We tentatively conclude that hybrid sterility can evolve without widespread, qualitative misexpression of transcripts in species hybrids. We suggest that, if more misexpression exists in sterile hybrids, it is likely to be quantitative, tissue-specific, and/ or limited to earlier developmental stages. Although several caveats apply, this study was a first attempt to determine the mechanistic basis of hybrid sterility, and one potential candidate gene has been identified for further study.

  9. Benefits of Qualitative Simulation for Managing Fluctuating Staffing Needs

    Energy Technology Data Exchange (ETDEWEB)

    T. T. Nichols

    2001-07-02

    Management of the High Level Waste Program Office at the Idaho National Environmental and Engineering Laboratory has projected oscillating future employment levels. A simple computer model was created to help convince management that qualitative modeling of ''soft'' variables can provide appreciable insight into the consequences and performance of alternative staffing policies. Advocacy of the model underlying the simulation or a particular strategy did not motivate the study, but rather a desire to instill enthusiasm and elicit new and improved conceptual models from management. Six qualitative and three quantitative generic insights to managing staffing levels are gained from the simulations. These insights in their generic form should be familiar to those knowledgeable of system dynamics or computer/instrument process control. Their potential usefulness to developing staffing strategies is stressed. The two primary overarching assertions that flow from the simulation results are: (1) the presence of multiple feedbacks, time delays, and continuous flows introduce instability into a personnel system that complicates the management of staffing levels. Many times ''soft'' variables, such as morale, productivity, and efficiency are the sources of such influences; and (2) such influences can be successfully modeled. In the case of the simple model used in these simulations, for example, the qualitative impact of a strategy using hiring and laying off as the sole managerial interventions is assessed.

  10. Benefits of Qualitative Simulation for Managing Fluctuating Staffing Needs

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, Todd Travis

    2001-07-01

    Management of the High Level Waste Program Office at the Idaho National Environmental and Engineering Laboratory has projected oscillating future employment levels. A simple computer model was created to help convince management that qualitative modeling of "soft" variables can provide appreciable insight into the consequences and performance of alternative staffing policies. Advocacy of the model underlying the simulation or a particular strategy did not motivate the study, but rather a desire to instill enthusiasm and elicit new and improved conceptual models from management. Six qualitative and three quantitative generic insights to managing staffing levels are gained from the simulations. These insights in their generic form should be familiar to those knowledgeable of system dynamics or computer/instrument process control. Their potential usefulness to developing staffing strategies is stressed. The two primary overarching assertions that flow from the simulation results are: 1) the presence of multiple feedbacks, time delays, and continuous flows introduce instability into a personnel system that complicates the management of staffing levels. Many times "soft" variables, such as morale, productivity, and efficiency are the sources of such influences; and 2) such influences can be successfully modeled. In the case of the simple model used in these simulations, for example, the qualitative impact of a strategy using hiring and laying off as the sole managerial interventions is assessed.

  11. Qualitative Evaluation of a Role Play Bullying Simulation.

    Science.gov (United States)

    Gillespie, Gordon L; Brown, Kathryn; Grubb, Paula; Shay, Amy; Montoya, Karen

    Bullying against nurses is becoming a pervasive problem. In this article, a role play simulation designed for undergraduate nursing students is described. In addition, the evaluation findings from a subsample of students who participated in a role play simulation addressing bullying behaviors are reported. Focus group sessions were completed with a subset of eight students who participated in the intervention. Sessions were audiorecorded, transcribed verbatim, and analyzed using Colaizzi's procedural steps for qualitative analysis. Themes derived from the data were "The Experience of Being Bullied", "Implementation of the Program", "Desired Outcome of the Program", and "Context of Bullying in the Nursing Profession". Role play simulation was an effective and active learning strategy to diffuse education on bullying in nursing practice. Bullying in nursing was identified as a problem worthy of incorporation into the undergraduate nursing curriculum. To further enhance the learning experience with role play simulation, adequate briefing instructions, opportunity to opt out of the role play, and comprehensive debriefing are essential.

  12. Hybrid2: The hybrid system simulation model, Version 1.0, user manual

    Energy Technology Data Exchange (ETDEWEB)

    Baring-Gould, E.I.

    1996-06-01

    In light of the large scale desire for energy in remote communities, especially in the developing world, the need for a detailed long term performance prediction model for hybrid power systems was seen. To meet these ends, engineers from the National Renewable Energy Laboratory (NREL) and the University of Massachusetts (UMass) have spent the last three years developing the Hybrid2 software. The Hybrid2 code provides a means to conduct long term, detailed simulations of the performance of a large array of hybrid power systems. This work acts as an introduction and users manual to the Hybrid2 software. The manual describes the Hybrid2 code, what is included with the software and instructs the user on the structure of the code. The manual also describes some of the major features of the Hybrid2 code as well as how to create projects and run hybrid system simulations. The Hybrid2 code test program is also discussed. Although every attempt has been made to make the Hybrid2 code easy to understand and use, this manual will allow many organizations to consider the long term advantages of using hybrid power systems instead of conventional petroleum based systems for remote power generation.

  13. Hybrid and Electric Advanced Vehicle Systems Simulation

    Science.gov (United States)

    Beach, R. F.; Hammond, R. A.; Mcgehee, R. K.

    1985-01-01

    Predefined components connected to represent wide variety of propulsion systems. Hybrid and Electric Advanced Vehicle System (HEAVY) computer program is flexible tool for evaluating performance and cost of electric and hybrid vehicle propulsion systems. Allows designer to quickly, conveniently, and economically predict performance of proposed drive train.

  14. Simulation of hybrid vehicle propulsion with an advanced battery model

    Energy Technology Data Exchange (ETDEWEB)

    Nallabolu, S.; Kostetzer, L.; Rudnyi, E. [CADFEM GmbH, Grafing (Germany); Geppert, M.; Quinger, D. [LION Smart GmbH, Frieding (Germany)

    2011-07-01

    In the recent years there has been observed an increasing concern about global warming and greenhouse gas emissions. In addition to the environmental issues the predicted scarcity of oil supplies and the dramatic increase in oil price puts new demands on vehicle design. As a result energy efficiency and reduced emission have become one of main selling point for automobiles. Hybrid electric vehicles (HEV) have therefore become an interesting technology for the governments and automotive industries. HEV are more complicated compared to conventional vehicles due to the fact that these vehicles contain more electrical components such as electric machines, power electronics, electronic continuously variable transmissions (CVT), and embedded powertrain controllers. Advanced energy storage devices and energy converters, such as Li-ion batteries, ultracapacitors, and fuel cells are also considered. A detailed vehicle model used for an energy flow analysis and vehicle performance simulation is necessary. Computer simulation is indispensible to facilitate the examination of the vast hybrid electric vehicle design space with the aim to predict the vehicle performance over driving profiles, estimate fuel consumption and the pollution emissions. There are various types of mathematical models and simulators available to perform system simulation of vehicle propulsion. One of the standard methods to model the complete vehicle powertrain is ''backward quasistatic modeling''. In this method vehicle subsystems are defined based on experiential models in the form of look-up tables and efficiency maps. The interaction between adjacent subsystems of the vehicle is defined through the amount of power flow. Modeling the vehicle subsystems like motor, engine, gearbox and battery is under this technique is based on block diagrams. The vehicle model is applied in two case studies to evaluate the vehicle performance and fuel consumption. In the first case study the affect

  15. Electric and plug-in hybrid vehicles advanced simulation methodologies

    CERN Document Server

    Varga, Bogdan Ovidiu; Moldovanu, Dan; Iclodean, Calin

    2015-01-01

    This book is designed as an interdisciplinary platform for specialists working in electric and plug-in hybrid electric vehicles powertrain design and development, and for scientists who want to get access to information related to electric and hybrid vehicle energy management, efficiency and control. The book presents the methodology of simulation that allows the specialist to evaluate electric and hybrid vehicle powertrain energy flow, efficiency, range and consumption. The mathematics behind each electric and hybrid vehicle component is explained and for each specific vehicle the powertrain

  16. Temperature field simulation of laser-TIG hybrid welding

    Institute of Scientific and Technical Information of China (English)

    陈彦宾; 李俐群; 方俊飞; 封小松; 吴林

    2003-01-01

    The three-dimensional transient temperature distribution of laser-TIG hybrid welding was analyzed and simulated numerically. Calculations were based on a finite element model, in which the physical process of hybrid welding was studied and the coupling effect of the laser and arc in the hybrid process was fully considered. The temperature fields and weld cross-sections of the typical welding parameters are obtained using present model. The calculation results show that the model can indicate the relationship of energy match between laser and arc to joints cross-sections objectively, and the simulation results are well agreed with the experimental results.

  17. Simulation of hybrid solar power plants

    Science.gov (United States)

    Dieckmann, Simon; Dersch, Jürgen

    2017-06-01

    Hybrid solar power plants have the potential to combine advantages of two different technologies at the cost of increased complexity. The present paper shows the potential of the software greenius for the techno-economic evaluation of hybrid solar power plants and discusses two exemplary scenarios. Depreciated Concentrated Solar Power (CSP) plants based on trough technology can be retrofitted with solar towers in order to reach higher steam cycle temperatures and hence efficiencies. Compared to a newly built tower plant the hybridization of a depreciated trough plant causes about 30% lower LCOE reaching 104 /MWh. The second hybrid scenario combines cost-efficient photovoltaics with dispatchable CSP technology. This hybrid plant offers very high capacity factors up to 69% based on 100% load from 8am to 11pm. The LCOE of the hybrid plant are only slightly lower (174 vs. 186 /MWh) compared to the pure CSP plant because the capital expenditure for thermal storage and power block remains the same while the electricity output is much lower.

  18. Global hybrid simulation of unmagnetized planets - Comparison of Venus and Mars

    Science.gov (United States)

    Brecht, Stephen H.; Ferrante, John R.

    1991-01-01

    Results from three-dimensional hybrid particle simulations of the solar wind interaction with the planets Mars and Venus are presented. The simulations produce shocks and magnetic barriers which are asymmetric. These results are qualitatively in agreement with data. In the absence of an ionosphere the subsolar shock standoff distance was found to agree with the observations if the Hall current is limited. It was also found that the solar wind interaction with Mars and Venus was substantially different. The interaction with Venus can be generally viewed as a magnetized interaction. The Mars interaction is very kinetic in nature and appears not to have a shock in the classic sense.

  19. SKIRT: Hybrid parallelization of radiative transfer simulations

    Science.gov (United States)

    Verstocken, S.; Van De Putte, D.; Camps, P.; Baes, M.

    2017-07-01

    We describe the design, implementation and performance of the new hybrid parallelization scheme in our Monte Carlo radiative transfer code SKIRT, which has been used extensively for modelling the continuum radiation of dusty astrophysical systems including late-type galaxies and dusty tori. The hybrid scheme combines distributed memory parallelization, using the standard Message Passing Interface (MPI) to communicate between processes, and shared memory parallelization, providing multiple execution threads within each process to avoid duplication of data structures. The synchronization between multiple threads is accomplished through atomic operations without high-level locking (also called lock-free programming). This improves the scaling behaviour of the code and substantially simplifies the implementation of the hybrid scheme. The result is an extremely flexible solution that adjusts to the number of available nodes, processors and memory, and consequently performs well on a wide variety of computing architectures.

  20. Thermal simulation of a cooling system of hybrid commercial vehicles; Thermalsimulation eine Hybrid-LKW-Kuehlsystems

    Energy Technology Data Exchange (ETDEWEB)

    Stroh, Christoph; Schnoerch, Stefan; Rathberger, Christian [Magna Powertrain Engineering Center Steyr GmbH und Co. KG, St. Valentin (Austria)

    2012-11-01

    In the past few years hybrid vehicles have been in the center of automotive engineering efforts, in particular in the field of passenger cars. But hybrid powertrains will also be important for commercial trucks. This focus on hybrid vehicles leads to high demands on thermal management since the additional components in a hybrid vehicle need appropriate cooling or even heating. In the given paper the simulation of a complete cooling system of a hybrid commercial vehicle will be explained. For this virtual examination the commercial 1D thermal management software KULI will be used, a co-simulation with several programs will not be done deliberately. Yet all aspects which are relevant for a global assessment of the thermal management are considered. The main focus is put on the investigation of appropriate concepts for the fluid circuits, including low and high temperature circuits, electric water pumps, etc. Moreover, also a refrigerant circuit with a chiller for active battery cooling will be used, the appropriate control strategy is implemented as well. For simulating transient profiles a simple driving simulation model is included, using road profile, ambient conditions, and various vehicle parameters as input. In addition an engine model is included which enables the investigation of fuel consumption potentials. This simulation model shows how the thermal management of a hybrid vehicle can be investigated with a single program and with reasonable effort. (orig.)

  1. Three-year randomised clinical trial to evaluate the clinical performance, quantitative and qualitative wear patterns of hybrid composite restorations.

    Science.gov (United States)

    Palaniappan, Senthamaraiselvi; Elsen, Liesbeth; Lijnen, Inge; Peumans, Marleen; Van Meerbeek, Bart; Lambrechts, Paul

    2010-08-01

    The aim of the study was to compare the clinical performance, quantitative and qualitative wear patterns of conventional hybrid (Tetric Ceram), micro-filled hybrid (Gradia Direct Posterior) and nano-hybrid (Tetric EvoCeram, TEC) posterior composite restorations in a 3-year randomised clinical trial. Sixteen Tetric Ceram, 17 TEC and 16 Gradia Direct Posterior restorations were placed in human molars and evaluated at baseline, 6, 12, 24 and 36 months of clinical service according to US Public Health Service criteria. The gypsum replicas at each recall were used for 3D laser scanning to quantify wear, and the epoxy resin replicas were observed under scanning electron microscope to study the qualitative wear patterns. After 3 years of clinical service, the three hybrid restorative materials performed clinically well in posterior cavities. Within the observation period, the nano-hybrid and micro-hybrid restorations evolved better in polishability with improved surface gloss retention than the conventional hybrid counterpart. The three hybrid composites showed enamel-like vertical wear and cavity-size dependant volume loss magnitude. Qualitatively, while the micro-filled and nano-hybrid composite restorations exhibited signs of fatigue similar to the conventional hybrid composite restorations at heavy occlusal contact area, their light occlusal contact areas showed less surface pitting after 3 years of clinical service.

  2. Towards Hybrid Overset Grid Simulations of the Launch Environment

    Science.gov (United States)

    Moini-Yekta, Shayan

    A hybrid overset grid approach has been developed for the design and analysis of launch vehicles and facilities in the launch environment. The motivation for the hybrid grid methodology is to reduce the turn-around time of computational fluid dynamic simulations and improve the ability to handle complex geometry and flow physics. The LAVA (Launch Ascent and Vehicle Aerodynamics) hybrid overset grid scheme consists of two components: an off-body immersed-boundary Cartesian solver with block-structured adaptive mesh refinement and a near-body unstructured body-fitted solver. Two-way coupling is achieved through overset connectivity between the off-body and near-body grids. This work highlights verification using code-to-code comparisons and validation using experimental data for the individual and hybrid solver. The hybrid overset grid methodology is applied to representative unsteady 2D trench and 3D generic rocket test cases.

  3. A Novel Software Simulator Model Based on Active Hybrid Architecture

    Directory of Open Access Journals (Sweden)

    Amr AbdElHamid

    2015-01-01

    Full Text Available The simulated training is an important issue for any type of missions such as aerial, ground, sea, or even space missions. In this paper, a new flexible aerial simulator based on active hybrid architecture is introduced. The simulator infrastructure is applicable to any type of training missions and research activities. This software-based simulator is tested on aerial missions to prove its applicability within time critical systems. The proposed active hybrid architecture is introduced via using the VB.NET and MATLAB in the same simulation loop. It exploits the remarkable computational power of MATLAB as a backbone aircraft model, and such mathematical model provides realistic dynamics to the trainee. Meanwhile, the Human-Machine Interface (HMI, the mission planning, the hardware interfacing, data logging, and MATLAB interfacing are developed using VB.NET. The proposed simulator is flexible enough to perform navigation and obstacle avoidance training missions. The active hybrid architecture is used during the simulated training, and also through postmission activities (like the generation of signals playback reports for evaluation purposes. The results show the ability of the proposed architecture to fulfill the aerial simulator demands and to provide a flexible infrastructure for different simulated mission requirements. Finally, a comparison with some existing simulators is introduced.

  4. A simulation approach to sizing hybrid photovoltaic and wind systems

    Science.gov (United States)

    Anderson, L. A.

    1983-12-01

    A simulation approach to sizing hybrid photovoltaic and wind systems provides a combination of components to realize zero downtime and minimum initial or life-cycle cost. Using Dayton, OH as a test site for weather data, cost advantages in the neighborhood of four are predicted for a hybrid system with battery storage when compared to a wind-energy-only system for the same electrical load.

  5. Pseudospectral Model for Hybrid PIC Hall-effect Thruster Simulation

    Science.gov (United States)

    2015-07-01

    1149. 8Goebel, D. M. and Katz, I., Fundamentals of Electric Propulsion : Ion and Hall Thrusters, John Wiley & Sons, Inc., 2008. 9Martin, R., J.W., K...Bilyeu, D., and Tran, J., “Dynamic Particle Weight Remapping in Hybrid PIC Hall -effect Thruster Simulation,” 34th Int. Electric Propulsion Conf...Paper 3. DATES COVERED (From - To) July 2015-July 2015 4. TITLE AND SUBTITLE Pseudospectral model for hybrid PIC Hall -effect thruster simulationect

  6. Sizing and Simulation of PV-Wind Hybrid Power System

    OpenAIRE

    Mustafa Engin

    2013-01-01

    A sizing procedure is developed for hybrid system with the aid of mathematical models for photovoltaic cell, wind turbine, and battery that are readily present in the literature. This sizing procedure can simulate the annual performance of different kinds of photovoltaic-wind hybrid power system structures for an identified set of renewable resources, which fulfills technical limitations with the lowest energy cost. The output of the program will display the performance of the system during t...

  7. Distributed Heterogeneous Simulation of a Hybrid-Electric Vehicle

    Science.gov (United States)

    2006-03-29

    operate as a generator to convert mechanical energy from the diesel t~nginc 01 from regenerative braking to electrical energy. A vehicle control module...Distributed Heterogeneous Simulation of a Hybrid- Electric Vehicle Ning Wu’, Curtis Rands t , Charles E. Lucas!, Eric A. Walters§, and Maher A...Masrurit US Army RDECOM-TARDEC, Warren, MI, 48397 Hybrid- electric military vehicles provide many advantages over conventional military vehicles powered

  8. Dynamic simulation of urban hybrid electric vehicles; Dynamische Simulation von Stadthybridfahrzeugen

    Energy Technology Data Exchange (ETDEWEB)

    Winke, Florian; Bargende, Michael [Stuttgart Univ. (Germany). Inst. fuer Verbrennungsmotoren und Kraftfahrwesen (IVK)

    2013-09-15

    As a result of the rising requirements on the development process of modern vehicles, simulation models for the prediction of fuel efficiency have become an irreplaceable tool in the automotive industry. Especially for the design of hybrid electric drivetrains, the increasingly short development cycles can only be met by the use of efficient simulation models. At the IVK of the University of Stuttgart, different approaches to simulating the longitudinal dynamics of hybrid electric vehicles were analysed and compared within the presented project. The focus of the investigations was on urban operation. The objective was to develop a hybrid vehicle concept that allows an equitable comparison with pure battery electric vehicles. (orig.)

  9. A Parallel Genetic Simulated Annealing Hybrid Algorithm for Task Scheduling

    Institute of Scientific and Technical Information of China (English)

    SHU Wanneng; ZHENG Shijue

    2006-01-01

    In this paper combined with the advantages of genetic algorithm and simulated annealing, brings forward a parallel genetic simulated annealing hybrid algorithm (PGSAHA) and applied to solve task scheduling problem in grid computing .It first generates a new group of individuals through genetic operation such as reproduction, crossover, mutation, etc, and than simulated anneals independently all the generated individuals respectively.When the temperature in the process of cooling no longer falls, the result is the optimal solution on the whole.From the analysis and experiment result, it is concluded that this algorithm is superior to genetic algorithm and simulated annealing.

  10. Pressure calculation in hybrid particle-field simulations.

    Science.gov (United States)

    Milano, Giuseppe; Kawakatsu, Toshihiro

    2010-12-07

    In the framework of a recently developed scheme for a hybrid particle-field simulation techniques where self-consistent field (SCF) theory and particle models (molecular dynamics) are combined [J. Chem. Phys. 130, 214106 (2009)], we developed a general formulation for the calculation of instantaneous pressure and stress tensor. The expressions have been derived from statistical mechanical definition of the pressure starting from the expression for the free energy functional in the SCF theory. An implementation of the derived formulation suitable for hybrid particle-field molecular dynamics-self-consistent field simulations is described. A series of test simulations on model systems are reported comparing the calculated pressure with those obtained from standard molecular dynamics simulations based on pair potentials.

  11. Hybrid simulation theory for a classical nonlinear dynamical system

    Science.gov (United States)

    Drazin, Paul L.; Govindjee, Sanjay

    2017-03-01

    Hybrid simulation is an experimental and computational technique which allows one to study the time evolution of a system by physically testing a subset of it while the remainder is represented by a numerical model that is attached to the physical portion via sensors and actuators. The technique allows one to study large or complicated mechanical systems while only requiring a subset of the complete system to be present in the laboratory. This results in vast cost savings as well as the ability to study systems that simply can not be tested due to scale. However, the errors that arise from splitting the system in two requires careful attention, if a valid simulation is to be guaranteed. To date, efforts to understand the theoretical limitations of hybrid simulation have been restricted to linear dynamical systems. In this work we consider the behavior of hybrid simulation when applied to nonlinear dynamical systems. As a model problem, we focus on the damped, harmonically-driven nonlinear pendulum. This system offers complex nonlinear characteristics, in particular periodic and chaotic motions. We are able to show that the application of hybrid simulation to nonlinear systems requires a careful understanding of what one expects from such an experiment. In particular, when system response is chaotic we advocate the need for the use of multiple metrics to characterize the difference between two chaotic systems via Lyapunov exponents and Lyapunov dimensions, as well as correlation exponents. When system response is periodic we advocate the use of L2 norms. Further, we are able to show that hybrid simulation can falsely predict chaotic or periodic response when the true system has the opposite characteristic. In certain cases, we are able to show that control system parameters can mitigate this issue.

  12. Simulating Strongly Correlated Electron Systems with Hybrid Monte Carlo

    Institute of Scientific and Technical Information of China (English)

    LIU Chuan

    2000-01-01

    Using the path integral representation, the Hubbard and the periodic Anderson model on D-dimensional cubic lattice are transformed into field theories of fermions in D + 1 dimensions. These theories at half-filling possess a positive definite real symmetry fermion matrix and can be simulated using the hybrid Monte Carlo method.

  13. A hybrid parallel framework for the cellular Potts model simulations

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yi [Los Alamos National Laboratory; He, Kejing [SOUTH CHINA UNIV; Dong, Shoubin [SOUTH CHINA UNIV

    2009-01-01

    The Cellular Potts Model (CPM) has been widely used for biological simulations. However, most current implementations are either sequential or approximated, which can't be used for large scale complex 3D simulation. In this paper we present a hybrid parallel framework for CPM simulations. The time-consuming POE solving, cell division, and cell reaction operation are distributed to clusters using the Message Passing Interface (MPI). The Monte Carlo lattice update is parallelized on shared-memory SMP system using OpenMP. Because the Monte Carlo lattice update is much faster than the POE solving and SMP systems are more and more common, this hybrid approach achieves good performance and high accuracy at the same time. Based on the parallel Cellular Potts Model, we studied the avascular tumor growth using a multiscale model. The application and performance analysis show that the hybrid parallel framework is quite efficient. The hybrid parallel CPM can be used for the large scale simulation ({approx}10{sup 8} sites) of complex collective behavior of numerous cells ({approx}10{sup 6}).

  14. Hybrid Techniques for Quantum Circuit Simulation

    Science.gov (United States)

    2014-02-01

    15 Figure 10. (a) Ripple-carry (Cuccaro) adder for 3...bit numbers [17]. (b) Average runtime and memory needed by Quipu and QuIDDPro (QPLite) to simulate -bit Cuccaro adders ...b) scaled adder , (c) binary-to- stochastic converter, and (d) stochastic-to-binary converter

  15. Wind Solar Hybrid System Rectifier Stage Topology Simulation

    Directory of Open Access Journals (Sweden)

    Anup M. Gakare

    2014-06-01

    Full Text Available This paper presents power-control strategies of a grid-connected hybrid generation system with versatile power transfer. The hybrid system allows maximum utilization of freely available renewable sources like wind and photovoltaic energies. This paper presents a new system configuration of the multi input rectifier stage for a hybrid wind and photovoltaic energy system. This configuration allows the two sources to supply the load simultaneously depending on the availability of the energy sources maximum power from the sun when it is available. An adaptive MPPT algorithm with a standard perturbs and observed method will be used for the Photo Voltaic system. The main advantage of the hybrid system is to give continuous power supply to the load. The gating pulses to the inverter switches are implemented with conventional and fuzzy controller. This hybrid wind-photo voltaic system is modeled in MATLAB/ SIMULINK environment. Simulation circuit is analyzed and results are presented for this hybrid wind and solar energy system.

  16. Simulation of Missile Autopilot with Two-Rate Hybrid Neural Network System

    Directory of Open Access Journals (Sweden)

    ASTROV, I.

    2007-04-01

    Full Text Available This paper proposes a two-rate hybrid neural network system, which consists of two artificial neural network subsystems. These neural network subsystems are used as the dynamic subsystems controllers.1 This is because such neuromorphic controllers are especially suitable to control complex systems. An illustrative example - two-rate neural network hybrid control of decomposed stochastic model of a rigid guided missile over different operating conditions - was carried out using the proposed two-rate state-space decomposition technique. This example demonstrates that this research technique results in simplified low-order autonomous control subsystems with various speeds of actuation, and shows the quality of the proposed technique. The obtained results show that the control tasks for the autonomous subsystems can be solved more qualitatively than for the original system. The simulation and animation results with use of software package Simulink demonstrate that this research technique would work for real-time stochastic systems.

  17. A hybrid approach to simulating mechanical properties of polymer nanocomposites.

    Science.gov (United States)

    Mccarron, Andy P; Raj, Sharad; Hyers, Robert; Kim, Moon K

    2009-12-01

    Empirical studies indicate that a polymer reinforced with nanoscale particles could enhance its mechanical properties such as stiffness and toughness. To give insight into how and why this nanoparticle reinforcement is effective, it is necessary to develop computational models that can accurately simulate the effects of nanoparticles on the fracture characteristics of polymer composites. Furthermore, a hybrid model that can account for both continuum and non-continuum effects will hasten the development of not only new hierarchical composite materials but also new theories to explain their behavior. This paper presents a hybrid modeling scheme for simulating fracture of polymer nanocomposites by utilizing an atomistic modeling approach called Elastic Network Model (ENM) in conjunction with a traditional Finite Element Analysis (FEA). The novelty of this hybrid ENM-FEA approach lies in its ability to model less interesting outer domains with FEA while still accounting for areas of interest such as crack tip reion and the interface between a nanoparticle and the polymer matrix at atomic scale with ENM. Various simulation conditions have been tested to determine the feasibility of the proposed hybrid model. For instance, an iterative result from a uniaxial loading with isotropic properties in an ENM-FEA model shows accuracy and convergence to the analytic solution.

  18. Hybrid Monte-Carlo simulation of interacting tight-binding model of graphene

    CERN Document Server

    Smith, Dominik

    2013-01-01

    In this work, results are presented of Hybrid-Monte-Carlo simulations of the tight-binding Hamiltonian of graphene, coupled to an instantaneous long-range two-body potential which is modeled by a Hubbard-Stratonovich auxiliary field. We present an investigation of the spontaneous breaking of the sublattice symmetry, which corresponds to a phase transition from a conducting to an insulating phase and which occurs when the effective fine-structure constant $\\alpha$ of the system crosses above a certain threshold $\\alpha_C$. Qualitative comparisons to earlier works on the subject (which used larger system sizes and higher statistics) are made and it is established that $\\alpha_C$ is of a plausible magnitude in our simulations. Also, we discuss differences between simulations using compact and non-compact variants of the Hubbard field and present a quantitative comparison of distinct discretization schemes of the Euclidean time-like dimension in the Fermion operator.

  19. Simulation and Test of a Fuel Cell Hybrid Golf Cart

    Directory of Open Access Journals (Sweden)

    Jingming Liang

    2014-01-01

    Full Text Available This paper establishes the simulation model of fuel cell hybrid golf cart (FCHGC, which applies the non-GUI mode of the Advanced Vehicle Simulator (ADVISOR and the genetic algorithm (GA to optimize it. Simulation of the objective function is composed of fuel consumption and vehicle dynamic performance; the variables are the fuel cell stack power sizes and the battery numbers. By means of simulation, the optimal parameters of vehicle power unit, fuel cell stack, and battery pack are worked out. On this basis, GUI mode of ADVISOR is used to select the rated power of vehicle motor. In line with simulation parameters, an electrical golf cart is refitted by adding a 2 kW hydrogen air proton exchange membrane fuel cell (PEMFC stack system and test the FCHGC. The result shows that the simulation data is effective but it needs improving compared with that of the real cart test.

  20. A Matlab—Based Simulation for Hybrid Electric Motorcycle

    Institute of Scientific and Technical Information of China (English)

    邵定国; 李永斌; 汪信尧; 江建中

    2003-01-01

    This paper presents a simulation and modeling package based on Matlab for a parallel hybrid electric motorcycle (HEM).The package consists of several main detailed models: internal combustion engine (ICE), motor, continuously variable transmission(CVT), battery, energy management system (EMS) etc. Each component is built as a library, and can be connected together accord-ing to the parallel HEM's topology. Simulation results, such as ICE power demand, motor power demand, battery instantaneous state-of-charge (SOC), pollution emissions etc. Are given and discussed. Lastly experimental data verify our simulation results.

  1. A Hybrid Model for Smoke Simulation

    Institute of Scientific and Technical Information of China (English)

    童若锋; 董金祥

    2002-01-01

    A smoke simulation approach based on the integration of traditional particlesystems and density functions is presented in this paper. By attaching a density function toeach particle as its attribute, the diffusion of smoke can be described by the variation of parti-cles' density functions, along with the effect on airflow by controlling particles' movement andfragmentation. In addition, a continuous density field for realistic rendering can be generatedquickly through the look-up tables of particle's density functions. Compared with traditionalparticle systems, this approach can describe smoke diffusion, and provide a continuous densityfield for realistic rendering with much less computation. A quick rendering scheme is also pre-sented in this paper as a useful preview tool for tuning appropriate parameters in the smokemodel.

  2. Hybrid simulation of electron cyclotron resonance heating

    CERN Document Server

    Ropponen, T; Suominen, P; Koponen, T K; Kalvas, T; Koivisto, H

    2008-01-01

    Electron Cyclotron Resonance (ECR) heating is a fundamentally important aspect in understanding the physics of Electron Cyclotron Resonance Ion Sources (ECRIS). Absorption of the radio frequency (RF) microwave power by electron heating in the resonance zone depends on many parameters including frequency and electric field strength of the microwave, magnetic field structure and electron and ion density profiles. ECR absorption has been studied in the past by e.g. modelling electric field behaviour in the resonance zone and its near proximity. This paper introduces a new ECR heating code that implements damping of the microwave power in the vicinity of the resonance zone, utilizes electron density profiles and uses right hand circularly polarized (RHCP) electromagnetic waves to simulate electron heating in ECRIS plasma.

  3. Battery thermal models for hybrid vehicle simulations

    Science.gov (United States)

    Pesaran, Ahmad A.

    This paper summarizes battery thermal modeling capabilities for: (1) an advanced vehicle simulator (ADVISOR); and (2) battery module and pack thermal design. The National Renewable Energy Laboratory's (NREL's) ADVISOR is developed in the Matlab/Simulink environment. There are several battery models in ADVISOR for various chemistry types. Each one of these models requires a thermal model to predict the temperature change that could affect battery performance parameters, such as resistance, capacity and state of charges. A lumped capacitance battery thermal model in the Matlab/Simulink environment was developed that included the ADVISOR battery performance models. For thermal evaluation and design of battery modules and packs, NREL has been using various computer aided engineering tools including commercial finite element analysis software. This paper will discuss the thermal ADVISOR battery model and its results, along with the results of finite element modeling that were presented at the workshop on "Development of Advanced Battery Engineering Models" in August 2001.

  4. Managing resource capacity using hybrid simulation

    Science.gov (United States)

    Ahmad, Norazura; Ghani, Noraida Abdul; Kamil, Anton Abdulbasah; Tahar, Razman Mat

    2014-12-01

    Due to the diversity of patient flows and interdependency of the emergency department (ED) with other units in hospital, the use of analytical models seems not practical for ED modeling. One effective approach to study the dynamic complexity of ED problems is by developing a computer simulation model that could be used to understand the structure and behavior of the system. Attempts to build a holistic model using DES only will be too complex while if only using SD will lack the detailed characteristics of the system. This paper discusses the combination of DES and SD in order to get a better representation of the actual system than using either modeling paradigm solely. The model is developed using AnyLogic software that will enable us to study patient flows and the complex interactions among hospital resources for ED operations. Results from the model show that patients' length of stay is influenced by laboratories turnaround time, bed occupancy rate and ward admission rate.

  5. Hybrid simulation of electron cyclotron resonance heating

    Energy Technology Data Exchange (ETDEWEB)

    Ropponen, T. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FI-40014 (Finland)], E-mail: tommi.ropponen@phys.jyu.fi; Tarvainen, O. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Suominen, P. [CERN Geneve 23, CH-1211 (Switzerland); Koponen, T.K. [Department of Physics, University of Jyvaeskylae, Nanoscience Center, P.O. Box 35, FI-40014 (Finland); Kalvas, T.; Koivisto, H. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FI-40014 (Finland)

    2008-03-11

    Electron Cyclotron Resonance (ECR) heating is a fundamentally important aspect in understanding the physics of Electron Cyclotron Resonance Ion Sources (ECRIS). Absorption of the radio frequency (RF) microwave power by electron heating in the resonance zone depends on many parameters including frequency and electric field strength of the microwave, magnetic field structure and electron and ion density profiles. ECR absorption has been studied in the past by e.g. modelling electric field behaviour in the resonance zone and its near proximity. This paper introduces a new ECR heating code that implements damping of the microwave power in the vicinity of the resonance zone, utilizes electron density profiles and uses right hand circularly polarized (RHCP) electromagnetic waves to simulate electron heating in ECRIS plasma.

  6. Utilization of MATLAB in Simulation of Linear Hybrid Circuits

    OpenAIRE

    BRANCIK, L.

    2003-01-01

    In the paper a MATLAB-based method for simulating transient phenomena in linear hybrid circuits containing parts with both lumped and distributed parameters is presented. Distributed parts of the circuit are multiconductor transmission lines, which can generally be nonuniform, with frequency-dependent parameters, and under nonzero initial voltage and/or current distributions. In principle a solution is formulated using the modified nodal analysis method in the frequency domain. Subsequently a...

  7. Characteristic of Ion loss as determined by hybrid simulations

    Science.gov (United States)

    Brecht, Stephen H.; Ledvina, Stephen

    2016-10-01

    One of the major objectives of the MAVEN mission is to determine the loss rate of oxygen ions from the atmosphere of Mars. It is thought that the oxygen ion loss represents a conduit for the loss of water from Mars. However, the actual measurements and estimates of global loss rates are very difficult because one needs an average over many orbits and full coverage of the loss regions of Mars; something that MAVEN will only accomplish with an extended mission. In the meantime global kinetic simulations are an avenue to gain further insight into the loss process and perhaps offer insight into the data analysis that will be performed on the MAVEN data. Hybrid particle codes provide self-consistent simulations of the ion dynamics occurring when the solar wind interacts with Mars.This paper reports the results of HALFSHEL hybrid code simulations of the solar wind interaction with Mars and the subsequent loss of oxygen ions in the form of O+ and O2+. Four simulations were performed representing different orientations of the crustal magnetic fields with the subsolar regions using a solar EUV flux representative of the moderate solar activity experienced by MAVEN. Loss rates will be presented as will evaluations of the distribution functions of the various loss ion species as accumulated at roughly 2 Rm for each of the four simulations. The results will be presented as faces on a box surrounding Mars so that one can evaluate regions such as that of the measured plasma plume. The plume feature has now been measured and is often seen in simulations. Finally, the losses and the subsequent velocity distributions will be compared between the various crustal magnetic field orientations.In summary, results from the HALFSHEL hybrid code will be presented. These results will address characteristics of the oxygen ions lost from Mars as a function of crustal magnetic field orientation. Further, they will be compared with respect to the regions surrounding Mars and the associated

  8. Qualitative, semi-quantitative, and quantitative simulation of the osmoregulation system in yeast.

    Science.gov (United States)

    Pang, Wei; Coghill, George M

    2015-05-01

    In this paper we demonstrate how Morven, a computational framework which can perform qualitative, semi-quantitative, and quantitative simulation of dynamical systems using the same model formalism, is applied to study the osmotic stress response pathway in yeast. First the Morven framework itself is briefly introduced in terms of the model formalism employed and output format. We then built a qualitative model for the biophysical process of the osmoregulation in yeast, and a global qualitative-level picture was obtained through qualitative simulation of this model. Furthermore, we constructed a Morven model based on existing quantitative model of the osmoregulation system. This model was then simulated qualitatively, semi-quantitatively, and quantitatively. The obtained simulation results are presented with an analysis. Finally the future development of the Morven framework for modelling the dynamic biological systems is discussed. Copyright © 2015 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

  9. STEM image simulation with hybrid CPU/GPU programming.

    Science.gov (United States)

    Yao, Y; Ge, B H; Shen, X; Wang, Y G; Yu, R C

    2016-07-01

    STEM image simulation is achieved via hybrid CPU/GPU programming under parallel algorithm architecture to speed up calculation on a personal computer (PC). To utilize the calculation power of a PC fully, the simulation is performed using the GPU core and multi-CPU cores at the same time to significantly improve efficiency. GaSb and an artificial GaSb/InAs interface with atom diffusion have been used to verify the computation. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Hybrid and electric advanced vehicle systems (heavy) simulation

    Science.gov (United States)

    Hammond, R. A.; Mcgehee, R. K.

    1981-01-01

    A computer program to simulate hybrid and electric advanced vehicle systems (HEAVY) is described. It is intended for use early in the design process: concept evaluation, alternative comparison, preliminary design, control and management strategy development, component sizing, and sensitivity studies. It allows the designer to quickly, conveniently, and economically predict the performance of a proposed drive train. The user defines the system to be simulated using a library of predefined component models that may be connected to represent a wide variety of propulsion systems. The development of three models are discussed as examples.

  11. Dynamic Garment Simulation based on Hybrid Bounding Volume Hierarchy

    Directory of Open Access Journals (Sweden)

    Zhu Dongyong

    2016-12-01

    Full Text Available In order to solve the computing speed and efficiency problem of existing dynamic clothing simulation, this paper presents a dynamic garment simulation based on a hybrid bounding volume hierarchy. It firstly uses MCASG graph theory to do the primary segmentation for a given three-dimensional human body model. And then it applies K-means cluster to do the secondary segmentation to collect the human body’s upper arms, lower arms, upper legs, lower legs, trunk, hip and woman’s chest as the elementary units of dynamic clothing simulation. According to different shapes of these elementary units, it chooses the closest and most efficient hybrid bounding box to specify these units, such as cylinder bounding box and elliptic cylinder bounding box. During the process of constructing these bounding boxes, it uses the least squares method and slices of the human body to get the related parameters. This approach makes it possible to use the least amount of bounding boxes to create close collision detection regions for the appearance of the human body. A spring-mass model based on a triangular mesh of the clothing model is finally constructed for dynamic simulation. The simulation result shows the feasibility and superiority of the method described.

  12. Multiscale Hy3S: Hybrid stochastic simulation for supercomputers

    Directory of Open Access Journals (Sweden)

    Kaznessis Yiannis N

    2006-02-01

    Full Text Available Abstract Background Stochastic simulation has become a useful tool to both study natural biological systems and design new synthetic ones. By capturing the intrinsic molecular fluctuations of "small" systems, these simulations produce a more accurate picture of single cell dynamics, including interesting phenomena missed by deterministic methods, such as noise-induced oscillations and transitions between stable states. However, the computational cost of the original stochastic simulation algorithm can be high, motivating the use of hybrid stochastic methods. Hybrid stochastic methods partition the system into multiple subsets and describe each subset as a different representation, such as a jump Markov, Poisson, continuous Markov, or deterministic process. By applying valid approximations and self-consistently merging disparate descriptions, a method can be considerably faster, while retaining accuracy. In this paper, we describe Hy3S, a collection of multiscale simulation programs. Results Building on our previous work on developing novel hybrid stochastic algorithms, we have created the Hy3S software package to enable scientists and engineers to both study and design extremely large well-mixed biological systems with many thousands of reactions and chemical species. We have added adaptive stochastic numerical integrators to permit the robust simulation of dynamically stiff biological systems. In addition, Hy3S has many useful features, including embarrassingly parallelized simulations with MPI; special discrete events, such as transcriptional and translation elongation and cell division; mid-simulation perturbations in both the number of molecules of species and reaction kinetic parameters; combinatorial variation of both initial conditions and kinetic parameters to enable sensitivity analysis; use of NetCDF optimized binary format to quickly read and write large datasets; and a simple graphical user interface, written in Matlab, to help users

  13. Vlasov Simulations of Ionospheric Heating Near Upper Hybrid Resonance

    Science.gov (United States)

    Najmi, A. C.; Eliasson, B. E.; Shao, X.; Milikh, G. M.; Papadopoulos, K.

    2014-12-01

    It is well-known that high-frequency (HF) heating of the ionosphere can excite field- aligned density striations (FAS) in the ionospheric plasma. Furthermore, in the neighborhood of various resonances, the pump wave can undergo parametric instabilities to produce a variety of electrostatic and electromagnetic waves. We have used a Vlasov simulation with 1-spatial dimension, 2-velocity dimensions, and 2-components of fields, to study the effects of ionospheric heating when the pump frequency is in the vicinity of the upper hybrid resonance, employing parameters currently available at ionospheric heaters such as HAARP. We have found that by seeding theplasma with a FAS of width ~20% of the simulation domain, ~10% depletion, and by applying a spatially uniform HF dipole pump electric field, the pump wave gives rise to a broad spectrum of density fluctuations as well as to upper hybrid and lower hybrid oscillating electric fields. We also observe collisionless bulk-heating of the electrons that varies non-linearly with the amplitude of the pump field.

  14. Hybrid Computational Simulation and Study of Terahertz Pulsed Photoconductive Antennas

    Science.gov (United States)

    Emadi, R.; Barani, N.; Safian, R.; Nezhad, A. Zeidaabadi

    2016-08-01

    A photoconductive antenna (PCA) has been numerically investigated in the terahertz (THz) frequency band based on a hybrid simulation method. This hybrid method utilizes an optoelectronic solver, Silvaco TCAD, and a full-wave electromagnetic solver, CST. The optoelectronic solver is used to find the accurate THz photocurrent by considering realistic material parameters. Performance of photoconductive antennas and temporal behavior of the excited photocurrent for various active region geometries such as bare-gap electrode, interdigitated electrodes, and tip-to-tip rectangular electrodes are investigated. Moreover, investigations have been done on the center of the laser illumination on the substrate, substrate carrier lifetime, and diffusion photocurrent associated with the carriers temperature, to achieve efficient and accurate photocurrent. Finally, using the full-wave electromagnetic solver and the calculated photocurrent obtained from the optoelectronic solver, electromagnetic radiation of the antenna and its associated detected THz signal are calculated and compared with a measurement reference for verification.

  15. Computational simulation of intermingled-fiber hybrid composite behavior

    Science.gov (United States)

    Mital, Subodh K.; Chamis, Christos C.

    1992-01-01

    Three-dimensional finite-element analysis and a micromechanics based computer code ICAN (Integrated Composite Analyzer) are used to predict the composite properties and microstresses of a unidirectional graphite/epoxy primary composite with varying percentages of S-glass fibers used as hydridizing fibers at a total fiber volume of 0.54. The three-dimensional finite-element model used in the analyses consists of a group of nine fibers, all unidirectional, in a three-by-three unit cell array. There is generally good agreement between the composite properties and microstresses obtained from both methods. The results indicate that the finite-element methods and the micromechanics equations embedded in the ICAN computer code can be used to obtain the properties of intermingled fiber hybrid composites needed for the analysis/design of hybrid composite structures. However, the finite-element model should be big enough to be able to simulate the conditions assumed in the micromechanics equations.

  16. Wind hybrid electrical supply system: behaviour simulation and sizing optimization

    Science.gov (United States)

    Notton, G.; Cristofari, C.; Poggi, P.; Muselli, M.

    2001-04-01

    Using a global approach, a wind hybrid system operation is simulated and the evolution of several parameters is analysed, such as the wasted energy, the fuel consumption and the role of the wind turbine subsystem in the global production. This analysis shows that all the energies which take part in the system operation are more dependent on the wind turbine size than on the battery storage capacity. A storage of 2 or 3 days is sufficient, because an increase in storage beyond these values does not have a notable impact on the performance of the wind hybrid system. Finally, a cost study is performed to determine the optimal configuration of the system conducive to the lowest cost of electricity production.

  17. Hybrid Computational Simulation and Study of Terahertz Pulsed Photoconductive Antennas

    Science.gov (United States)

    Emadi, R.; Barani, N.; Safian, R.; Nezhad, A. Zeidaabadi

    2016-11-01

    A photoconductive antenna (PCA) has been numerically investigated in the terahertz (THz) frequency band based on a hybrid simulation method. This hybrid method utilizes an optoelectronic solver, Silvaco TCAD, and a full-wave electromagnetic solver, CST. The optoelectronic solver is used to find the accurate THz photocurrent by considering realistic material parameters. Performance of photoconductive antennas and temporal behavior of the excited photocurrent for various active region geometries such as bare-gap electrode, interdigitated electrodes, and tip-to-tip rectangular electrodes are investigated. Moreover, investigations have been done on the center of the laser illumination on the substrate, substrate carrier lifetime, and diffusion photocurrent associated with the carriers temperature, to achieve efficient and accurate photocurrent. Finally, using the full-wave electromagnetic solver and the calculated photocurrent obtained from the optoelectronic solver, electromagnetic radiation of the antenna and its associated detected THz signal are calculated and compared with a measurement reference for verification.

  18. Large-scale nanocomposites simulations using hybrid particle/SCFT simulations

    Science.gov (United States)

    Sides, Scott

    2009-03-01

    Preliminary results from 2D simulations of block copolymer nanocomposites (Phys. Rev. Lett. Vol 96, 250601 (2006) have been performed using a hybrid self-consistent field theory (SCFT) algorithm. While these simulation results showed that the presence of nanoparticles could induce changes in block copolymer morphologies, quantitative agreement with experiments for the particle densities at this transition are not yet possible. A feature missing in the 2D hybrid simulations is the packing behavior of real, three-dimensional spherical particles embedded in lamellar layers or hexagonally packed cylinders formed by linear diblock chains. In order to carry out these hybrid particle/SCFT 3D simulations a new object-oriented SCFT framework has been developed. The object-oriented design enables the hybrid/SCFT simulations to be performed in a framework that is both numerically efficient and sufficiently flexible to incorporate new SCFT models easily, In particular, this new framework will be used to investigate the distribution of particle positions in diblock lamellar layers as function of nanoparticle density to study the interplay of patterning due to diblock domain structure and the chain depletion interaction between spherical particles.

  19. A hybrid algorithm for parallel molecular dynamics simulations

    CERN Document Server

    Mangiardi, Chris M

    2016-01-01

    This article describes an algorithm for hybrid parallelization and SIMD vectorization of molecular dynamics simulations with short-ranged forces. The parallelization method combines domain decomposition with a thread-based parallelization approach. The goal of the work is to enable efficient simulations of very large (tens of millions of atoms) and inhomogeneous systems on many-core processors with hundreds or thousands of cores and SIMD units with large vector sizes. In order to test the efficiency of the method, simulations of a variety of configurations with up to 74 million atoms have been performed. Results are shown that were obtained on multi-core systems with AVX and AVX-2 processors as well as Xeon-Phi co-processors.

  20. A hybrid algorithm for parallel molecular dynamics simulations

    Science.gov (United States)

    Mangiardi, Chris M.; Meyer, R.

    2017-10-01

    This article describes algorithms for the hybrid parallelization and SIMD vectorization of molecular dynamics simulations with short-range forces. The parallelization method combines domain decomposition with a thread-based parallelization approach. The goal of the work is to enable efficient simulations of very large (tens of millions of atoms) and inhomogeneous systems on many-core processors with hundreds or thousands of cores and SIMD units with large vector sizes. In order to test the efficiency of the method, simulations of a variety of configurations with up to 74 million atoms have been performed. Results are shown that were obtained on multi-core systems with Sandy Bridge and Haswell processors as well as systems with Xeon Phi many-core processors.

  1. Dynamic Hybrid Simulation of the Lunar Wake During ARTEMIS Crossing

    Science.gov (United States)

    Wiehle, S.; Plaschke, F.; Angelopoulos, V.; Auster, H.; Glassmeier, K.; Kriegel, H.; Motschmann, U. M.; Mueller, J.

    2010-12-01

    The interaction of the highly dynamic solar wind with the Moon is simulated with the A.I.K.E.F. (Adaptive Ion Kinetic Electron Fluid) code for the ARTEMIS P1 flyby on February 13, 2010. The A.I.K.E.F. hybrid plasma simulation code is the improved version of the Braunschweig code. It is able to automatically increase simulation grid resolution in areas of interest during runtime, which greatly increases resolution as well as performance. As the Moon has no intrinsic magnetic field and no ionosphere, the solar wind particles are absorbed at its surface, resulting in the formation of the lunar wake at the nightside. The solar wind magnetic field is basically convected through the Moon and the wake is slowly filled up with solar wind particles. However, this interaction is strongly influenced by the highly dynamic solar wind during the flyby. This is considered by a dynamic variation of the upstream conditions in the simulation using OMNI solar wind measurement data. By this method, a very good agreement between simulation and observations is achieved. The simulations show that the stationary structure of the lunar wake constitutes a tableau vivant in space representing the well-known Friedrichs diagram for MHD waves.

  2. Utilization of MATLAB in Simulation of Linear Hybrid Circuits

    Directory of Open Access Journals (Sweden)

    L. Brancik

    2003-12-01

    Full Text Available In the paper a MATLAB-based method for simulating transientphenomena in linear hybrid circuits containing parts with both lumpedand distributed parameters is presented. Distributed parts of thecircuit are multiconductor transmission lines, which can generally benonuniform, with frequency-dependent parameters, and under nonzeroinitial voltage and/or current distributions. In principle a solutionis formulated using the modified nodal analysis method in the frequencydomain. Subsequently an improved fast method of the numerical inversionof Laplace transforms in the vector or matrix form is applied to obtainsolution in the time domain.

  3. Hybrid multiscale simulation of a mixing-controlled reaction

    Energy Technology Data Exchange (ETDEWEB)

    Scheibe, Timothy D.; Schuchardt, Karen L.; Agarwal, Khushbu; Chase, Jared M.; Yang, Xiaofan; Palmer, Bruce J.; Tartakovsky, Alexandre M.; Elsethagen, Todd O.; Redden, George D.

    2015-09-01

    Continuum-scale models have been used to study subsurface flow, transport, and reactions for many years but lack the capability to resolve fine-grained processes. Recently, pore-scale models, which operate at scales of individual soil grains, have been developed to more accurately model and study pore-scale phenomena, such as mineral precipitation and dissolution reactions, microbially-mediated surface reactions, and other complex processes. However, these highly-resolved models are prohibitively expensive for modeling domains of sizes relevant to practical problems. To broaden the utility of pore-scale models for larger domains, we developed a hybrid multiscale model that initially simulates the full domain at the continuum scale and applies a pore-scale model only to areas of high reactivity. Since the location and number of pore-scale model regions in the model varies as the reactions proceed, an adaptive script defines the number and location of pore regions within each continuum iteration and initializes pore-scale simulations from macroscale information. Another script communicates information from the pore-scale simulation results back to the continuum scale. These components provide loose coupling between the pore- and continuum-scale codes into a single hybrid multiscale model implemented within the SWIFT workflow environment. In this paper, we consider an irreversible homogenous bimolecular reaction (two solutes reacting to form a third solute) in a 2D test problem. This paper is focused on the approach used for multiscale coupling between pore- and continuum-scale models, application to a realistic test problem, and implications of the results for predictive simulation of mixing-controlled reactions in porous media. Our results and analysis demonstrate that loose coupling provides a feasible, efficient and scalable approach for multiscale subsurface simulations.

  4. Sizing and Simulation of PV-Wind Hybrid Power System

    Directory of Open Access Journals (Sweden)

    Mustafa Engin

    2013-01-01

    Full Text Available A sizing procedure is developed for hybrid system with the aid of mathematical models for photovoltaic cell, wind turbine, and battery that are readily present in the literature. This sizing procedure can simulate the annual performance of different kinds of photovoltaic-wind hybrid power system structures for an identified set of renewable resources, which fulfills technical limitations with the lowest energy cost. The output of the program will display the performance of the system during the year, the total cost of the system, and the best size for the PV-generator, wind generator, and battery capacity. Security lightning application is selected, whereas system performance data and environmental operating conditions are measured and stored. This hybrid system, which includes a PV, wind turbine, inverter, and a battery, was installed to supply energy to 24 W lamps, considering that the renewable energy resources of this site where the system was installed were 1700 Wh/m2/day solar radiation and 3.43 m/s yearly average wind speed. Using the measured variables, the inverter and charge regulator efficiencies were calculated as 90% and 98%, respectively, and the overall system’s electrical efficiency is calculated as 72%. Life cycle costs per kWh are found to be $0.89 and LLP = 0.0428.

  5. A hybrid atomistic electrodynamics-quantum mechanical approach for simulating surface-enhanced Raman scattering.

    Science.gov (United States)

    Payton, John L; Morton, Seth M; Moore, Justin E; Jensen, Lasse

    2014-01-21

    Surface-enhanced Raman scattering (SERS) is a technique that has broad implications for biological and chemical sensing applications by providing the ability to simultaneously detect and identify a single molecule. The Raman scattering of molecules adsorbed on metal nanoparticles can be enhanced by many orders of magnitude. These enhancements stem from a twofold mechanism: an electromagnetic mechanism (EM), which is due to the enhanced local field near the metal surface, and a chemical mechanism (CM), which is due to the adsorbate specific interactions between the metal surface and the molecules. The local field near the metal surface can be significantly enhanced due to the plasmon excitation, and therefore chemists generally accept that the EM provides the majority of the enhancements. While classical electrodynamics simulations can accurately simulate the local electric field around metal nanoparticles, they offer few insights into the spectral changes that occur in SERS. First-principles simulations can directly predict the Raman spectrum but are limited to small metal clusters and therefore are often used for understanding the CM. Thus, there is a need for developing new methods that bridge the electrodynamics simulations of the metal nanoparticle and the first-principles simulations of the molecule to facilitate direct simulations of SERS spectra. In this Account, we discuss our recent work on developing a hybrid atomistic electrodynamics-quantum mechanical approach to simulate SERS. This hybrid method is called the discrete interaction model/quantum mechanics (DIM/QM) method and consists of an atomistic electrodynamics model of the metal nanoparticle and a time-dependent density functional theory (TDDFT) description of the molecule. In contrast to most previous work, the DIM/QM method enables us to retain a detailed atomistic structure of the nanoparticle and provides a natural bridge between the electronic structure methods and the macroscopic

  6. Hybrid molecular dynamics simulation for plasma induced damage analysis

    Science.gov (United States)

    Matsukuma, Masaaki

    2016-09-01

    In order to enable further device size reduction (also known as Moore's law) and improved power performance, the semiconductor industry is introducing new materials and device structures into the semiconductor fabrication process. Materials now include III-V compounds, germanium, cobalt, ruthenium, hafnium, and others. The device structure in both memory and logic has been evolving from planar to three dimensional (3D). One such device is the FinFET, where the transistor gate is a vertical fin made either of silicon, silicon-germanium or germanium. These changes have brought renewed interests in the structural damages caused by energetic ion bombardment of the fin sidewalls which are exposed to the ion flux from the plasma during the fin-strip off step. Better control of the physical damage of the 3D devices requires a better understanding of the damage formation mechanisms on such new materials and structures. In this study, the damage formation processes by ion bombardment have been simulated for Si and Ge substrate by Quantum Mechanics/Molecular Mechanics (QM/MM) hybrid simulations and compared to the results from the classical molecular dynamics (MD) simulations. In our QM/MM simulations, the highly reactive region in which the structural damage is created is simulated with the Density Functional based Tight Binding (DFTB) method and the region remote from the primary region is simulated using classical MD with the Stillinger-Weber and Moliere potentials. The learn on the fly method is also used to reduce the computational load. Hence our QM/MM simulation is much faster than the full QC-MD simulations and the original QM/MM simulations. The amorphous layers profile simulated with QM/MM have obvious differences in their thickness for silicon and germanium substrate. The profile of damaged structure in the germanium substrate is characterized by a deeper tail then in silicon. These traits are also observed in the results from the mass selected ion beam

  7. Hybrid simulation of metal oxide surge-arrester thermal behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Huang, L.; Raghuveer, M.R. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Electrical and Computer Engineering

    1996-01-01

    A finite-difference-based technique for simulating the thermal behaviour of a metal oxide surge arrester (MOSA) was described. The improved hybrid thermal modelling technique was claimed to accurately represent heat-transfer modes. Fin theory was used to represent arrester sheds. The proposed model, which relies on simple measurements at the arrester terminals, yields the temporal variation of temperature in a MOSA in both the axial and radial direction. The thermal behaviour of a MOSA under steady-state and transient conditions can be simulated using such a model under different environmental conditions. The accuracy of the modelling technique was demonstrated experimentally by measurements conducted on an arrester. 15 refs., 7 figs.

  8. Software development infrastructure for the HYBRID modeling and simulation project

    Energy Technology Data Exchange (ETDEWEB)

    Aaron S. Epiney; Robert A. Kinoshita; Jong Suk Kim; Cristian Rabiti; M. Scott Greenwood

    2016-09-01

    One of the goals of the HYBRID modeling and simulation project is to assess the economic viability of hybrid systems in a market that contains renewable energy sources like wind. The idea is that it is possible for the nuclear plant to sell non-electric energy cushions, which absorb (at least partially) the volatility introduced by the renewable energy sources. This system is currently modeled in the Modelica programming language. To assess the economics of the system, an optimization procedure is trying to find the minimal cost of electricity production. The RAVEN code is used as a driver for the whole problem. It is assumed that at this stage, the HYBRID modeling and simulation framework can be classified as non-safety “research and development” software. The associated quality level is Quality Level 3 software. This imposes low requirements on quality control, testing and documentation. The quality level could change as the application development continues.Despite the low quality requirement level, a workflow for the HYBRID developers has been defined that include a coding standard and some documentation and testing requirements. The repository performs automated unit testing of contributed models. The automated testing is achieved via an open-source python script called BuildingsP from Lawrence Berkeley National Lab. BuildingsPy runs Modelica simulation tests using Dymola in an automated manner and generates and runs unit tests from Modelica scripts written by developers. In order to assure effective communication between the different national laboratories a biweekly videoconference has been set-up, where developers can report their progress and issues. In addition, periodic face-face meetings are organized intended to discuss high-level strategy decisions with management. A second means of communication is the developer email list. This is a list to which everybody can send emails that will be received by the collective of the developers and managers

  9. Hybrid practices as a means to implement quality improvement: A comparative qualitative study in a Dutch and Swedish hospital.

    Science.gov (United States)

    Quartz-Topp, Julia; Sanne, Johan M; Pöstges, Heide

    2016-11-15

    Managers and scholars commonly perceive resistance from professionals as hampering the implementation of quality improvement (QI) and refer to the incompatibility of clinical and managerial approaches to QI as a reason. Yet a growing body of research indicates that, in practice, these two approaches rather blend into hybrid practices that embody different types of QI-related knowledge and values. This opens up a new perspective on implementation challenges that moves attention away from resistance against managerial QI toward difficulties for clinicians to draw together different types of knowledge and values within their clinical work. So far, little is known about how managers can support clinicians to generate hybrid QI practices. The aim of this study was to deepen our understanding of how managers can support the generation of hybrid practices that help clinicians to integrate QI into their everyday work. We draw on comparative qualitative research including 21 semistructured interviews, documentary analysis, and participant observation that we conducted in one Dutch and one Swedish hospital over a period of 8 months in 2011/2012. Hospital managers designed hybrid forums, tools, and professional roles in order to facilitate the integration of different QI practices, knowledge, and values. This integration generated new hybrid practices and an infrastructure for QI that has potential to support clinicians in their efforts to align different demands. New opportunities to implement QI emerge when we change the implementation problem from clinical resistance to the need of support for clinicians to develop hybrid QI practices. Hospital managers then have to intentionally organize for the generation of hybrid practices by designing, for example, hybrid forums, tools, and professional roles that integrate different knowledge and values in a nonhierarchical way.

  10. Accelerating Climate and Weather Simulations through Hybrid Computing

    Science.gov (United States)

    Zhou, Shujia; Cruz, Carlos; Duffy, Daniel; Tucker, Robert; Purcell, Mark

    2011-01-01

    Unconventional multi- and many-core processors (e.g. IBM (R) Cell B.E.(TM) and NVIDIA (R) GPU) have emerged as effective accelerators in trial climate and weather simulations. Yet these climate and weather models typically run on parallel computers with conventional processors (e.g. Intel, AMD, and IBM) using Message Passing Interface. To address challenges involved in efficiently and easily connecting accelerators to parallel computers, we investigated using IBM's Dynamic Application Virtualization (TM) (IBM DAV) software in a prototype hybrid computing system with representative climate and weather model components. The hybrid system comprises two Intel blades and two IBM QS22 Cell B.E. blades, connected with both InfiniBand(R) (IB) and 1-Gigabit Ethernet. The system significantly accelerates a solar radiation model component by offloading compute-intensive calculations to the Cell blades. Systematic tests show that IBM DAV can seamlessly offload compute-intensive calculations from Intel blades to Cell B.E. blades in a scalable, load-balanced manner. However, noticeable communication overhead was observed, mainly due to IP over the IB protocol. Full utilization of IB Sockets Direct Protocol and the lower latency production version of IBM DAV will reduce this overhead.

  11. A hybrid simulation model for a stable auroral arc

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    Full Text Available We present a new type of hybrid simulation model, intended to simulate a single stable auroral arc in the latitude/altitude plane. The ionospheric ions are treated as particles, the electrons are assumed to follow a Boltzmann response and the magnetospheric ions are assumed to be so hot that they form a background population unaffected by the electric fields that arise. The system is driven by assumed parallel electron energisation causing a primary negative charge cloud and an associated potential structure to build up. The results show how a closed potential structure and density depletion of an auroral arc build up and how they decay after the driver is turned off. The model also produces upgoing energetic ion beams and predicts strong static perpendicular electric fields to be found in a relatively narrow altitude range (~ 5000–11 000 km.

    Key words. Magnetospheric physics (magnetosphere-ionosphere interactions; auroral phenomena – Space plasma physics (numerical simulation studies

  12. Hybrid framework for the simulation of stochastic chemical kinetics

    Science.gov (United States)

    Duncan, Andrew; Erban, Radek; Zygalakis, Konstantinos

    2016-12-01

    Stochasticity plays a fundamental role in various biochemical processes, such as cell regulatory networks and enzyme cascades. Isothermal, well-mixed systems can be modelled as Markov processes, typically simulated using the Gillespie Stochastic Simulation Algorithm (SSA) [25]. While easy to implement and exact, the computational cost of using the Gillespie SSA to simulate such systems can become prohibitive as the frequency of reaction events increases. This has motivated numerous coarse-grained schemes, where the "fast" reactions are approximated either using Langevin dynamics or deterministically. While such approaches provide a good approximation when all reactants are abundant, the approximation breaks down when one or more species exist only in small concentrations and the fluctuations arising from the discrete nature of the reactions become significant. This is particularly problematic when using such methods to compute statistics of extinction times for chemical species, as well as simulating non-equilibrium systems such as cell-cycle models in which a single species can cycle between abundance and scarcity. In this paper, a hybrid jump-diffusion model for simulating well-mixed stochastic kinetics is derived. It acts as a bridge between the Gillespie SSA and the chemical Langevin equation. For low reactant reactions the underlying behaviour is purely discrete, while purely diffusive when the concentrations of all species are large, with the two different behaviours coexisting in the intermediate region. A bound on the weak error in the classical large volume scaling limit is obtained, and three different numerical discretisations of the jump-diffusion model are described. The benefits of such a formalism are illustrated using computational examples.

  13. A Fast Hybrid Approach to Air Shower Simulations and Applications

    CERN Document Server

    Drescher, H J; Bleicher, M; Reiter, M; Soff, S; Stöcker, H; Stoecker, Horst

    2003-01-01

    The SENECA model, a new hybrid approach to air shower simulations, is presented. It combines the use of efficient cascade equations in the energy range where a shower can be treated as one-dimensional, with a traditional Monte Carlo method which traces individual particles. This allows one to reproduce natural fluctuations of individual showers as well as the lateral spread of low energy particles. The model is quite efficient in computation time. As an application of the new approach, the influence of the low energy hadronic models on shower properties for AUGER energies is studied. We conclude that these models have a significant impact on the tails of lateral distribution functions, and deserve therefore more attention.

  14. Hybrid method of solution applied to simulation of pulse chromatography

    Directory of Open Access Journals (Sweden)

    M. A. Cremasco

    2009-06-01

    Full Text Available In this communication, the method proposed by Cremasco et al. (2003 is applied to predict single and low concentration pulse chromatography. In previous work, a general rate model was presented to describe the breakthrough curve, where a hybrid solution was proposed for the linear adsorption. The liquid phase concentration inside the particle was found analytically and related with the bed liquid phase through Duhamel's Theorem, while the bulk-phase equation was solved by a numerical method. In this paper, this method is applied to describe pulse chromatography of solutes that present linear adsorption isotherms. The simulated results of pulse chromatography are compared with experimental ones for aromatic amino acid experiments from literature.

  15. Perspective: Theory and simulation of hybrid halide perovskites

    Science.gov (United States)

    Whalley, Lucy D.; Frost, Jarvist M.; Jung, Young-Kwang; Walsh, Aron

    2017-06-01

    Organic-inorganic halide perovskites present a number of challenges for first-principles atomistic materials modeling. Such "plastic crystals" feature dynamic processes across multiple length and time scales. These include the following: (i) transport of slow ions and fast electrons; (ii) highly anharmonic lattice dynamics with short phonon lifetimes; (iii) local symmetry breaking of the average crystallographic space group; (iv) strong relativistic (spin-orbit coupling) effects on the electronic band structure; and (v) thermodynamic metastability and rapid chemical breakdown. These issues, which affect the operation of solar cells, are outlined in this perspective. We also discuss general guidelines for performing quantitative and predictive simulations of these materials, which are relevant to metal-organic frameworks and other hybrid semiconducting, dielectric and ferroelectric compounds.

  16. A Hybrid Flight Control for a Simulated Raptor-30 V2 Helicopter

    Directory of Open Access Journals (Sweden)

    Arbab Nighat Khizer

    2015-04-01

    Full Text Available This paper presents a hybrid flight control system for a single rotor simulated Raptor-30 V2 helicopter. Hybrid intelligent control system, combination of the conventional and intelligent control methodologies, is applied to small model helicopter. The proposed hybrid control used PID as a traditional control and fuzzy as an intelligent control so as to take the maximum advantage of advanced control theory. The helicopter?s model used; comes from X-Plane flight simulator and their hybrid flight control system was simulated using MATLAB/SIMULINK in a simulation platform. X-Plane is also used to visualize the performance of this proposed autopilot design. Through a series of numerous experiments, the operation of hybrid control system was investigated. Results verified that the proposed hybrid control has an excellent performance at hovering flight mode.

  17. Control-relevant modeling and simulation of a SOFC-GT hybrid system

    Directory of Open Access Journals (Sweden)

    Rambabu Kandepu

    2006-07-01

    Full Text Available In this paper, control-relevant models of the most important components in a SOFC-GT hybrid system are described. Dynamic simulations are performed on the overall hybrid system. The model is used to develop a simple control structure, but the simulations show that more elaborate control is needed.

  18. Plasma environment of Titan: a 3-D hybrid simulation study

    Directory of Open Access Journals (Sweden)

    S. Simon

    2006-05-01

    Full Text Available Titan possesses a dense atmosphere, consisting mainly of molecular nitrogen. Titan's orbit is located within the Saturnian magnetosphere most of the time, where the corotating plasma flow is super-Alfvénic, yet subsonic and submagnetosonic. Since Titan does not possess a significant intrinsic magnetic field, the incident plasma interacts directly with the atmosphere and ionosphere. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's interaction with the corotating magnetospheric plasma flow. For this reason, Titan's plasma environment has been studied by using a 3-D hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The calculations are performed on a curvilinear simulation grid which is adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation; hence, the local ion production rate depends on the solar zenith angle. Because the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. In general, the mechanism giving rise to these structures exhibits similarities to the interaction of the ionospheres of Mars and Venus with the supersonic solar wind. The simulation results are in agreement with data from recent Cassini flybys.

  19. A wind turbine hybrid simulation framework considering aeroelastic effects

    Science.gov (United States)

    Song, Wei; Su, Weihua

    2015-04-01

    In performing an effective structural analysis for wind turbine, the simulation of turbine aerodynamic loads is of great importance. The interaction between the wake flow and the blades may impact turbine blades loading condition, energy yield and operational behavior. Direct experimental measurement of wind flow field and wind profiles around wind turbines is very helpful to support the wind turbine design. However, with the growth of the size of wind turbines for higher energy output, it is not convenient to obtain all the desired data in wind-tunnel and field tests. In this paper, firstly the modeling of dynamic responses of large-span wind turbine blades will consider nonlinear aeroelastic effects. A strain-based geometrically nonlinear beam formulation will be used for the basic structural dynamic modeling, which will be coupled with unsteady aerodynamic equations and rigid-body rotations of the rotor. Full wind turbines can be modeled by using the multi-connected beams. Then, a hybrid simulation experimental framework is proposed to potentially address this issue. The aerodynamic-dominant components, such as the turbine blades and rotor, are simulated as numerical components using the nonlinear aeroelastic model; while the turbine tower, where the collapse of failure may occur under high level of wind load, is simulated separately as the physical component. With the proposed framework, dynamic behavior of NREL's 5MW wind turbine blades will be studied and correlated with available numerical data. The current work will be the basis of the authors' further studies on flow control and hazard mitigation on wind turbine blades and towers.

  20. The Virtual ChemLab Project: A Realistic and Sophisticated Simulation of Inorganic Qualitative Analysis

    Science.gov (United States)

    Woodfield, Brian F.; Catlin, Heidi R.; Waddoups, Gregory L.; Moore, Melissa S.; Swan, Richard; Allen, Rob; Bodily, Greg

    2004-11-01

    We have created a set of sophisticated and realistic laboratory simulations for use in freshman- and sophomore-level chemistry classes and laboratories called Virtual ChemLab. We have completed simulations for Inorganic Qualitative Analysis, Organic Synthesis and Organic Qualitative Analysis, Experiments in Quantum Chemistry, Gas Properties, Titration Experiments, and Calorimetric and Thermochemical Experiments. The purpose of our simulations is to reinforce concepts taught in the classroom, provide an environment for creative learning, and emphasize the thinking behind instructional laboratory experiments. We have used the inorganic simulation extensively with thousands of students in our department at Brigham Young University. We have learned from our evaluation that: (i) students enjoy using these simulations and find them to be an asset in learning effective problem-solving strategies, (ii) students like the fact that they can both reproduce experimental procedures and explore various topics in ways they choose, and (iii) students naturally divide themselves into two groups: creative learners, who excel in an open-ended environment of virtual laboratories, and structured learners, who struggle in this same environment. In this article, we describe the Inorganic Qualitative Analysis simulation; we also share specific evaluation findings from using the inorganic simulation in classroom and laboratory settings.

  1. Quantum Simulations of Solvated Biomolecules Using Hybrid Methods

    Science.gov (United States)

    Hodak, Miroslav

    2009-03-01

    One of the most important challenges in quantum simulations on biomolecules is efficient and accurate inclusion of the solvent, because the solvent atoms usually outnumber those in the biomolecule of interest. We have developed a hybrid method that allows for explicit quantum-mechanical treatment of the solvent at low computational cost. In this method, Kohn-Sham (KS) density functional theory (DFT) is combined with an orbital-free (OF) DFT. Kohn-Sham (KS) DFT is used to describe the biomolecule and its first solvation shells, while the orbital-free (OF) DFT is employed for the rest of the solvent. The OF part is fully O(N) and capable of handling 10^5 solvent molecules on current parallel supercomputers, while taking only ˜ 10 % of the total time. The compatibility between the KS and OF DFT methods enables seamless integration between the two. In particular, the flow of solvent molecules across the KS/OF interface is allowed and the total energy is conserved. As the first large-scale applications, the hybrid method has been used to investigate the binding of copper ions to proteins involved in prion (PrP) and Parkinson's diseases. Our results for the PrP, which causes mad cow disease when misfolded, resolve a contradiction found in experiments, in which a stronger binding mode is replaced by a weaker one when concentration of copper ions is increased, and show how it can act as a copper buffer. Furthermore, incorporation of copper stabilizes the structure of the full-length PrP, suggesting its protective role in prion diseases. For alpha-synuclein, a Parkinson's disease (PD) protein, we show that Cu binding modifies the protein structurally, making it more susceptible to misfolding -- an initial step in the onset of PD. In collaboration with W. Lu, F. Rose and J. Bernholc.

  2. Hybrid Simulation Modeling to Estimate U.S. Energy Elasticities

    Science.gov (United States)

    Baylin-Stern, Adam C.

    This paper demonstrates how an U.S. application of CIMS, a technologically explicit and behaviourally realistic energy-economy simulation model which includes macro-economic feedbacks, can be used to derive estimates of elasticity of substitution (ESUB) and autonomous energy efficiency index (AEEI) parameters. The ability of economies to reduce greenhouse gas emissions depends on the potential for households and industry to decrease overall energy usage, and move from higher to lower emissions fuels. Energy economists commonly refer to ESUB estimates to understand the degree of responsiveness of various sectors of an economy, and use estimates to inform computable general equilibrium models used to study climate policies. Using CIMS, I have generated a set of future, 'pseudo-data' based on a series of simulations in which I vary energy and capital input prices over a wide range. I then used this data set to estimate the parameters for transcendental logarithmic production functions using regression techniques. From the production function parameter estimates, I calculated an array of elasticity of substitution values between input pairs. Additionally, this paper demonstrates how CIMS can be used to calculate price-independent changes in energy-efficiency in the form of the AEEI, by comparing energy consumption between technologically frozen and 'business as usual' simulations. The paper concludes with some ideas for model and methodological improvement, and how these might figure into future work in the estimation of ESUBs from CIMS. Keywords: Elasticity of substitution; hybrid energy-economy model; translog; autonomous energy efficiency index; rebound effect; fuel switching.

  3. Estimating qualitative parameters for assessment of body balance in a simulated ambulatory setting

    NARCIS (Netherlands)

    Meulen, van Fokke B.; Reenalda, Jasper; Veltink, Peter H.

    2013-01-01

    Continuous daily-life monitoring of balance control of stroke survivors in an ambulatory setting, is essential for optimal guidance of rehabilitation. The purpose of this study is to demonstrate the relation between qualitative parameters of body balance while measuring in stroke patients in a simul

  4. A Hybrid Analytical/Simulation Modeling Approach for Planning and Optimizing Mass Tactical Airborne Operations

    Science.gov (United States)

    1995-05-01

    A HYBRID ANALYTICAL/ SIMULATION MODELING APPROACH FOR PLANNING AND OPTIMIZING MASS TACTICAL AIRBORNE OPERATIONS by DAVID DOUGLAS BRIGGS M.S.B.A...COVERED MAY 1995 TECHNICAL REPORT THESIS 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS A HYBRID ANALYTICAL SIMULATION MODELING APPROACH FOR PLANNING AND...are present. Thus, simulation modeling presents itself as an excellent alternate tool for planning because it allows for the modeling of highly complex

  5. Hybrid correspondence analysis and correlation to analyze the market position from data with two qualitative and p-2 quantitative variables

    Science.gov (United States)

    Ginanjar, Irlandia

    2015-12-01

    Analysis of the market position will be easier, efficient, and informative when based on a perceptual map, that can display objects and characteristics. With perceptual map we can identify the information about the objects similarity, the characteristics relationships, and relationship between the object and the characteristics. Characteristics of the object are usually more than two variables, those variables that sometimes are qualitative and some are quantitative. Based on that this paper introduce a method of analysis called hybrid correspondence analysis and correlation (HCAC), this method is the incorporation of correspondence analysis (CA) with biplot of correlation, where the mapped of two qualitative variables is using CA, and for quantitative variables is using correlations. HCAC produces a perceptual map that displays the object, the qualitative characteristics, and quantitative characteristics in a single map, without changing the quantitative data into qualitative data, so that the information obtained is more complete. A reference for mapping quality is counted from the first and second cumulative percent of eigenvalues where resulting from CA.

  6. Hybrid Multilevel Monte Carlo Simulation of Stochastic Reaction Networks

    KAUST Repository

    Moraes, Alvaro

    2015-01-07

    Stochastic reaction networks (SRNs) is a class of continuous-time Markov chains intended to describe, from the kinetic point of view, the time-evolution of chemical systems in which molecules of different chemical species undergo a finite set of reaction channels. This talk is based on articles [4, 5, 6], where we are interested in the following problem: given a SRN, X, defined though its set of reaction channels, and its initial state, x0, estimate E (g(X(T))); that is, the expected value of a scalar observable, g, of the process, X, at a fixed time, T. This problem lead us to define a series of Monte Carlo estimators, M, such that, with high probability can produce values close to the quantity of interest, E (g(X(T))). More specifically, given a user-selected tolerance, TOL, and a small confidence level, η, find an estimator, M, based on approximate sampled paths of X, such that, P (|E (g(X(T))) − M| ≤ TOL) ≥ 1 − η; even more, we want to achieve this objective with near optimal computational work. We first introduce a hybrid path-simulation scheme based on the well-known stochastic simulation algorithm (SSA)[3] and the tau-leap method [2]. Then, we introduce a Multilevel Monte Carlo strategy that allows us to achieve a computational complexity of order O(T OL−2), this is the same computational complexity as in an exact method but with a smaller constant. We provide numerical examples to show our results.

  7. SIMULATION OF WIRELESS SENSOR NETWORK WITH HYBRID TOPOLOGY

    Directory of Open Access Journals (Sweden)

    J. Jaslin Deva Gifty

    2016-03-01

    Full Text Available The design of low rate Wireless Personal Area Network (WPAN by IEEE 802.15.4 standard has been developed to support lower data rates and low power consuming application. Zigbee Wireless Sensor Network (WSN works on the network and application layer in IEEE 802.15.4. Zigbee network can be configured in star, tree or mesh topology. The performance varies from topology to topology. The performance parameters such as network lifetime, energy consumption, throughput, delay in data delivery and sensor field coverage area varies depending on the network topology. In this paper, designing of hybrid topology by using two possible combinations such as star-tree and star-mesh is simulated to verify the communication reliability. This approach is to combine all the benefits of two network model. The parameters such as jitter, delay and throughput are measured for these scenarios. Further, MAC parameters impact such as beacon order (BO and super frame order (SO for low power consumption and high channel utilization, has been analysed for star, tree and mesh topology in beacon disable mode and beacon enable mode by varying CBR traffic loads.

  8. Modeling and simulation of a hybrid ship power system

    Science.gov (United States)

    Doktorcik, Christopher J.

    2011-12-01

    Optimizing the performance of naval ship power systems requires integrated design and coordination of the respective subsystems (sources, converters, and loads). A significant challenge in the system-level integration is solving the Power Management Control Problem (PMCP). The PMCP entails deciding on subsystem power usages for achieving a trade-off between the error in tracking a desired position/velocity profile, minimizing fuel consumption, and ensuring stable system operation, while at the same time meeting performance limitations of each subsystem. As such, the PMCP naturally arises at a supervisory level of a ship's operation. In this research, several critical steps toward the solution of the PMCP for surface ships have been undertaken. First, new behavioral models have been developed for gas turbine engines, wound rotor synchronous machines, DC super-capacitors, induction machines, and ship propulsion systems. Conventional models describe system inputs and outputs in terms of physical variables such as voltage, current, torque, and force. In contrast, the behavioral models developed herein express system inputs and outputs in terms of power whenever possible. Additionally, the models have been configured to form a hybrid system-level power model (HSPM) of a proposed ship electrical architecture. Lastly, several simulation studies have been completed to expose the capabilities and limitations of the HSPM.

  9. Broadband ground-motion simulation using a hybrid approach

    Science.gov (United States)

    Graves, R.W.; Pitarka, A.

    2010-01-01

    This paper describes refinements to the hybrid broadband ground-motion simulation methodology of Graves and Pitarka (2004), which combines a deterministic approach at low frequencies (f 1 Hz). In our approach, fault rupture is represented kinematically and incorporates spatial heterogeneity in slip, rupture speed, and rise time. The prescribed slip distribution is constrained to follow an inverse wavenumber-squared fall-off and the average rupture speed is set at 80% of the local shear-wave velocity, which is then adjusted such that the rupture propagates faster in regions of high slip and slower in regions of low slip. We use a Kostrov-like slip-rate function having a rise time proportional to the square root of slip, with the average rise time across the entire fault constrained empirically. Recent observations from large surface rupturing earthquakes indicate a reduction of rupture propagation speed and lengthening of rise time in the near surface, which we model by applying a 70% reduction of the rupture speed and increasing the rise time by a factor of 2 in a zone extending from the surface to a depth of 5 km. We demonstrate the fidelity of the technique by modeling the strong-motion recordings from the Imperial Valley, Loma Prieta, Landers, and Northridge earthquakes.

  10. Dynamic simulation and optimal control strategy for a parallel hybrid hydraulic excavator

    Institute of Scientific and Technical Information of China (English)

    Xiao LIN; Shuang-xia PAN; Dong-yun WANG

    2008-01-01

    The primary focus of this study is to investigate the control strategies of a hybrid system used in hydraulic excavators. First, the structure and evaluation target of hybrid hydraulic excavators are analyzed. Then the dynamic system model including batteries, motor and engine is built as the simulation environment to obtain control results. A so-called multi-work-point dynamic control strategy, which has both closed-loop speed PI (proportion integral) control and direct torque control, is proposed and studied in the simulation model. Simulation results indicate that the hybrid system with this strategy can meet the power demand and achieve better system stability and higher fuel efficiency.

  11. Dynamic Modeling and Simulation on a Hybrid Power System for Electric Vehicle Applications

    Directory of Open Access Journals (Sweden)

    Hong-Wen He

    2010-11-01

    Full Text Available Hybrid power systems, formed by combining high-energy-density batteries and high-power-density ultracapacitors in appropriate ways, provide high-performance and high-efficiency power systems for electric vehicle applications. This paper first establishes dynamic models for the ultracapacitor, the battery and a passive hybrid power system, and then based on the dynamic models a comparative simulation between a battery only power system and the proposed hybrid power system was done under the UDDS (Urban Dynamometer Driving Schedule. The simulation results showed that the hybrid power system could greatly optimize and improve the efficiency of the batteries and their dynamic current was also decreased due to the participation of the ultracapacitors, which would have a good influence on batteries’ cycle life. Finally, the parameter matching for the passive hybrid power system was studied by simulation and comparisons.

  12. 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

    The global climate change leads to more extreme meteorological conditions such as icing weather, which have caused great losses to power systems. Comprehensive simulation tools are required to enhance the capability of power system risk assessment under extreme weather conditions. A hybrid...... 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....../E enabling hybrid simulation of icing event and power system disturbance is developed, based on which a hybrid simulation platform is established. Numerical studies show that the functionality of power system simulation is greatly extended by taking into account the icing weather events....

  13. Generation of hybrid meshes for the simulation of petroleum reservoirs; Generation de maillages hybrides pour la simulation de reservoirs petroliers

    Energy Technology Data Exchange (ETDEWEB)

    Balaven-Clermidy, S.

    2001-12-01

    Oil reservoir simulations study multiphase flows in porous media. These flows are described and evaluated through numerical schemes on a discretization of the reservoir domain. In this thesis, we were interested in this spatial discretization and a new kind of hybrid mesh has been proposed where the radial nature of flows in the vicinity of wells is directly taken into account in the geometry. Our modular approach described wells and their drainage area through radial circular meshes. These well meshes are inserted in a structured reservoir mesh (a Corner Point Geometry mesh) made up with hexahedral cells. Finally, in order to generate a global conforming mesh, proper connections are realized between the different kinds of meshes through unstructured transition ones. To compute these transition meshes that we want acceptable in terms of finite volume methods, an automatic method based on power diagrams has been developed. Our approach can deal with a homogeneous anisotropic medium and allows the user to insert vertical or horizontal wells as well as secondary faults in the reservoir mesh. Our work has been implemented, tested and validated in 2D and 2D1/2. It can also be extended in 3D when the geometrical constraints are simplicial ones: points, segments and triangles. (author)

  14. Numerical Simulations of Flow and Fuel Regression Rate Coupling in Hybrid Rocket Motors

    Directory of Open Access Journals (Sweden)

    Marius STOIA-DJESKA

    2017-03-01

    Full Text Available The hybrid propulsion offers some remarkable advantages like high safety and high specific impulse and thus it is considered a promising technology for the next generation launchers and space systems. The purpose of this work is to validate a design tool for hybrid rocket motors (HRM through numerical simulations.

  15. Monte Carlo Simulation of Dosimetric Parameters for HYBRID PdI Source in Brachytherapy

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    A novel brachytherapy source model, ADVANTAGE HYBRID PdI, has been designed by CIAE For treatment of cancer. In this project, the purpose of this study is to obtain the dosimetric parameters of HYBRID PdI source. The Monte Carlo simulation

  16. Co-Simulation of Hybrid Systems with SpaceEx and Uppaal

    DEFF Research Database (Denmark)

    Bogomolov, Sergiy; Greitschus, Marius; Jensen, Peter Gjøl

    2015-01-01

    The Functional Mock-up Interface (FMI) is an industry standard which enables co-simulation of complex heterogeneous systems using multiple simulation engines. In this paper, we show how to use FMI in order to co-simulate hybrid systems modeled in the model checkers SPACEEX and UPPAAL. We show how...

  17. An Integrated Qualitative and Quantitative Biochemical Model Learning Framework Using Evolutionary Strategy and Simulated Annealing.

    Science.gov (United States)

    Wu, Zujian; Pang, Wei; Coghill, George M

    2015-01-01

    Both qualitative and quantitative model learning frameworks for biochemical systems have been studied in computational systems biology. In this research, after introducing two forms of pre-defined component patterns to represent biochemical models, we propose an integrative qualitative and quantitative modelling framework for inferring biochemical systems. In the proposed framework, interactions between reactants in the candidate models for a target biochemical system are evolved and eventually identified by the application of a qualitative model learning approach with an evolution strategy. Kinetic rates of the models generated from qualitative model learning are then further optimised by employing a quantitative approach with simulated annealing. Experimental results indicate that our proposed integrative framework is feasible to learn the relationships between biochemical reactants qualitatively and to make the model replicate the behaviours of the target system by optimising the kinetic rates quantitatively. Moreover, potential reactants of a target biochemical system can be discovered by hypothesising complex reactants in the synthetic models. Based on the biochemical models learned from the proposed framework, biologists can further perform experimental study in wet laboratory. In this way, natural biochemical systems can be better understood.

  18. HRSSA - Efficient hybrid stochastic simulation for spatially homogeneous biochemical reaction networks

    Science.gov (United States)

    Marchetti, Luca; Priami, Corrado; Thanh, Vo Hong

    2016-07-01

    This paper introduces HRSSA (Hybrid Rejection-based Stochastic Simulation Algorithm), a new efficient hybrid stochastic simulation algorithm for spatially homogeneous biochemical reaction networks. HRSSA is built on top of RSSA, an exact stochastic simulation algorithm which relies on propensity bounds to select next reaction firings and to reduce the average number of reaction propensity updates needed during the simulation. HRSSA exploits the computational advantage of propensity bounds to manage time-varying transition propensities and to apply dynamic partitioning of reactions, which constitute the two most significant bottlenecks of hybrid simulation. A comprehensive set of simulation benchmarks is provided for evaluating performance and accuracy of HRSSA against other state of the art algorithms.

  19. HRSSA – Efficient hybrid stochastic simulation for spatially homogeneous biochemical reaction networks

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti, Luca, E-mail: marchetti@cosbi.eu [The Microsoft Research – University of Trento Centre for Computational and Systems Biology (COSBI), Piazza Manifattura, 1, 38068 Rovereto (Italy); Priami, Corrado, E-mail: priami@cosbi.eu [The Microsoft Research – University of Trento Centre for Computational and Systems Biology (COSBI), Piazza Manifattura, 1, 38068 Rovereto (Italy); University of Trento, Department of Mathematics (Italy); Thanh, Vo Hong, E-mail: vo@cosbi.eu [The Microsoft Research – University of Trento Centre for Computational and Systems Biology (COSBI), Piazza Manifattura, 1, 38068 Rovereto (Italy)

    2016-07-15

    This paper introduces HRSSA (Hybrid Rejection-based Stochastic Simulation Algorithm), a new efficient hybrid stochastic simulation algorithm for spatially homogeneous biochemical reaction networks. HRSSA is built on top of RSSA, an exact stochastic simulation algorithm which relies on propensity bounds to select next reaction firings and to reduce the average number of reaction propensity updates needed during the simulation. HRSSA exploits the computational advantage of propensity bounds to manage time-varying transition propensities and to apply dynamic partitioning of reactions, which constitute the two most significant bottlenecks of hybrid simulation. A comprehensive set of simulation benchmarks is provided for evaluating performance and accuracy of HRSSA against other state of the art algorithms.

  20. A new method for qualitative simulation of water resources systems: 2. Applications

    Science.gov (United States)

    Antunes, M. P.; Seixas, M. J.; Camara, A. S.; Pinheiro, M.

    1987-11-01

    SLIN (Simulação Linguistica) is a new method for qualitative dynamic simulation. As was presented previously (Camara et al., this issue), SLIN relies upon a categorical representation of variables which are manipulated by logical rules. Two applications to water resources systems are included to illustrate SLIN's potential usefulness: the environmental impact evaluation of a hydropower plant and the assessment of oil dispersion in the sea after a tanker wreck.

  1. A new method for qualitative simulation of water resources systems: 1. Theory

    Science.gov (United States)

    Camara, A. S.; Pinheiro, M.; Antunes, M. P.; Seixas, M. J.

    1987-11-01

    A new dynamic modeling methodology, SLIN (Simulação Linguistica), allowing for the analysis of systems defined by linguistic variables, is presented. SLIN applies a set of logical rules avoiding fuzzy theoretic concepts. To make the transition from qualitative to quantitative modes, logical rules are used as well. Extensions of the methodology to simulation-optimization applications and multiexpert system modeling are also discussed.

  2. New method for qualitative simulations of water resources systems. 2. Applications

    Energy Technology Data Exchange (ETDEWEB)

    Antunes, M.P.; Seixas, M.J.; Camara, A.S.; Pinheiro, M.

    1987-11-01

    SLIN (Simulacao Linguistica) is a new method for qualitative dynamic simulation. As was presented previously, SLIN relies upon a categorical representation of variables which are manipulated by logical rules. Two applications to water resources systems are included to illustrate SLIN's potential usefulness: the environmental impact evaluation of a hydropower plant and the assessment of oil dispersion in the sea after a tanker wreck.

  3. Reduction Methods for Real-time Simulations in Hybrid Testing

    DEFF Research Database (Denmark)

    Andersen, Sebastian

    2016-01-01

    Hybrid testing constitutes a cost-effective experimental full scale testing method. The method was introduced in the 1960's by Japanese researchers, as an alternative to conventional full scale testing and small scale material testing, such as shake table tests. The principle of the method...... is to divide a structure into a physical substructure and a numerical substructure, and couple these in a test. If the test is conducted in real-time it is referred to as real time hybrid testing. The hybrid testing concept has developed significantly since its introduction in the 1960', both with respect...... without introducing further unknowns into the system. The basis formulation is shown to exhibit high precision and to reduce the computational cost significantly. Furthermore, the basis formulation exhibits a significant higher stability, than standard nonlinear algorithms. A real-time hybrid test...

  4. Qualitative and quantitative simulation of androgen receptor antagonists: A case study of polybrominated diphenyl ethers.

    Science.gov (United States)

    Wu, Yang; Shi, Wei; Xia, Pu; Zhang, Xiaowei; Yu, Hongxia

    2017-12-15

    Recently, great attention has been paid to the identification and prediction of the androgen disrupting potencies of polybrominated diphenyl ethers (PBDEs). However, few existing models can discriminate active and inactive compounds, which make the quantitative prediction process including the quantitative structure-activity relationship (QSAR) technique unreliable. In this study, different grouping methods were investigated and compared for qualitative identification, including molecular docking and molecular dynamics simulations (MD). The results showed that qualitative identification based on MD, which is lab-independent, accurate and closer to the real transcriptional activation process, could separate 90.5% of active and inactive chemicals and was preferred. The 3D-QSAR models built as the quantitative simulation method showed r(2) and q(2) values of 0.513 and 0.980, respectively. Together, a novel workflow combining qualitative identification and quantitative simulations was generated with processes including activeness discrimination and activity prediction. This workflow, for analyzing the antagonism of androgen receptor (AR) of PBDEs is not only allowing researchers to reduce their intense laboratory experiments but also assisting them in inspecting and adjusting their laboratory systems and results. Copyright © 2017. Published by Elsevier B.V.

  5. Modeling and simulation of surfactant-polymer flooding using a new hybrid method

    Science.gov (United States)

    Daripa, Prabir; Dutta, Sourav

    2017-04-01

    Chemical enhanced oil recovery by surfactant-polymer (SP) flooding has been studied in two space dimensions. A new global pressure for incompressible, immiscible, multicomponent two-phase porous media flow has been derived in the context of SP flooding. This has been used to formulate a system of flow equations that incorporates the effect of capillary pressure and also the effect of polymer and surfactant on viscosity, interfacial tension and relative permeabilities of the two phases. The coupled system of equations for pressure, water saturation, polymer concentration and surfactant concentration has been solved using a new hybrid method in which the elliptic global pressure equation is solved using a discontinuous finite element method and the transport equations for water saturation and concentrations of the components are solved by a Modified Method Of Characteristics (MMOC) in the multicomponent setting. Numerical simulations have been performed to validate the method, both qualitatively and quantitatively, and to evaluate the relative performance of the various flooding schemes for several different heterogeneous reservoirs.

  6. Probing particle acceleration in lower hybrid turbulence via synthetic diagnostics produced by PIC simulations

    Science.gov (United States)

    Cruz, F.; Fonseca, R. A.; Silva, L. O.; Rigby, A.; Gregori, G.; Bamford, R. A.; Bingham, R.; Koenig, M.

    2016-10-01

    Efficient particle acceleration in astrophysical shocks can only be achieved in the presence of initial high energy particles. A candidate mechanism to provide an initial seed of energetic particles is lower hybrid turbulence (LHT). This type of turbulence is commonly excited in regions where space and astrophysical plasmas interact with large obstacles. Due to the nature of LH waves, energy can be resonantly transferred from ions (travelling perpendicular to the magnetic field) to electrons (travelling parallel to it) and the consequent motion of the latter in turbulent shock electromagnetic fields is believed to be responsible for the observed x-ray fluxes from non-thermal electrons produced in astrophysical shocks. Here we present PIC simulations of plasma flows colliding with magnetized obstacles showing the formation of a bow shock and the consequent development of LHT. The plasma and obstacle parameters are chosen in order to reproduce the results obtained in a recent experiment conducted at the LULI laser facility at Ecole Polytechnique (France) to study accelerated electrons via LHT. The wave and particle spectra are studied and used to produce synthetic diagnostics that show good qualitative agreement with experimental results. Work supported by the European Research Council (Accelerates ERC-2010-AdG 267841).

  7. A study on optimization of hybrid drive train using Advanced Vehicle Simulator (ADVISOR)

    Science.gov (United States)

    Same, Adam; Stipe, Alex; Grossman, David; Park, Jae Wan

    This study investigates the advantages and disadvantages of three hybrid drive train configurations: series, parallel, and "through-the-ground" parallel. Power flow simulations are conducted with the MATLAB/Simulink-based software ADVISOR. These simulations are then applied in an application for the UC Davis SAE Formula Hybrid vehicle. ADVISOR performs simulation calculations for vehicle position using a combined backward/forward method. These simulations are used to study how efficiency and agility are affected by the motor, fuel converter, and hybrid configuration. Three different vehicle models are developed to optimize the drive train of a vehicle for three stages of the SAE Formula Hybrid competition: autocross, endurance, and acceleration. Input cycles are created based on rough estimates of track geometry. The output from these ADVISOR simulations is a series of plots of velocity profile and energy storage State of Charge that provide a good estimate of how the Formula Hybrid vehicle will perform on the given course. The most noticeable discrepancy between the input cycle and the actual velocity profile of the vehicle occurs during deceleration. A weighted ranking system is developed to organize the simulation results and to determine the best drive train configuration for the Formula Hybrid vehicle. Results show that the through-the-ground parallel configuration with front-mounted motors achieves an optimal balance of efficiency, simplicity, and cost. ADVISOR is proven to be a useful tool for vehicle power train design for the SAE Formula Hybrid competition. This vehicle model based on ADVISOR simulation is applicable to various studies concerning performance and efficiency of hybrid drive trains.

  8. A study on optimization of hybrid drive train using Advanced Vehicle Simulator (ADVISOR)

    Energy Technology Data Exchange (ETDEWEB)

    Same, Adam; Stipe, Alex; Grossman, David; Park, Jae Wan [Department of Mechanical and Aeronautical Engineering, University of California, Davis, One Shields Ave, Davis, CA 95616 (United States)

    2010-10-01

    This study investigates the advantages and disadvantages of three hybrid drive train configurations: series, parallel, and ''through-the-ground'' parallel. Power flow simulations are conducted with the MATLAB/Simulink-based software ADVISOR. These simulations are then applied in an application for the UC Davis SAE Formula Hybrid vehicle. ADVISOR performs simulation calculations for vehicle position using a combined backward/forward method. These simulations are used to study how efficiency and agility are affected by the motor, fuel converter, and hybrid configuration. Three different vehicle models are developed to optimize the drive train of a vehicle for three stages of the SAE Formula Hybrid competition: autocross, endurance, and acceleration. Input cycles are created based on rough estimates of track geometry. The output from these ADVISOR simulations is a series of plots of velocity profile and energy storage State of Charge that provide a good estimate of how the Formula Hybrid vehicle will perform on the given course. The most noticeable discrepancy between the input cycle and the actual velocity profile of the vehicle occurs during deceleration. A weighted ranking system is developed to organize the simulation results and to determine the best drive train configuration for the Formula Hybrid vehicle. Results show that the through-the-ground parallel configuration with front-mounted motors achieves an optimal balance of efficiency, simplicity, and cost. ADVISOR is proven to be a useful tool for vehicle power train design for the SAE Formula Hybrid competition. This vehicle model based on ADVISOR simulation is applicable to various studies concerning performance and efficiency of hybrid drive trains. (author)

  9. Simulating Four Essential Conversations with Hematology/Oncology Trainees: a Qualitative Evaluation.

    Science.gov (United States)

    Arnaoutakis, Konstantinos; Anders, Michael; Berry, Katherine

    2016-03-01

    Hematologists/oncologists have a crucial responsibility to effectively communicate with patients. However, they have been criticized for ineffective communication with patients. To develop effective communication behaviors that meet the needs of patients and families, trainees need practice and feedback about their performance. Medical faculties frequently teach communication skills using simulation-based curricula; however, they often include only general communication skills, without tailored approaches for specialties. This study examined Hematology/Oncology trainees' qualitative perceptions about the value of and techniques used for simulations of specialty specific, essential conversations with patients and families, and debriefing sessions. Results demonstrate a highly effective curriculum and positive learner experiences. While most reports on this topic take place within major academic cancer centers, outcomes from a mid-sized Hematology/Oncology training program are unknown. The study confirms feasibility for implementing a simulation-based communications program in a mid-sized Hematology/Oncology program and describes simulation techniques that were effective.

  10. Hybrid statistics-simulations based method for atom-counting from ADF STEM images.

    Science.gov (United States)

    De Wael, Annelies; De Backer, Annick; Jones, Lewys; Nellist, Peter D; Van Aert, Sandra

    2017-01-25

    A hybrid statistics-simulations based method for atom-counting from annular dark field scanning transmission electron microscopy (ADF STEM) images of monotype crystalline nanostructures is presented. Different atom-counting methods already exist for model-like systems. However, the increasing relevance of radiation damage in the study of nanostructures demands a method that allows atom-counting from low dose images with a low signal-to-noise ratio. Therefore, the hybrid method directly includes prior knowledge from image simulations into the existing statistics-based method for atom-counting, and accounts in this manner for possible discrepancies between actual and simulated experimental conditions. It is shown by means of simulations and experiments that this hybrid method outperforms the statistics-based method, especially for low electron doses and small nanoparticles. The analysis of a simulated low dose image of a small nanoparticle suggests that this method allows for far more reliable quantitative analysis of beam-sensitive materials.

  11. Qualitative Comparative Analysis: A Hybrid Method for Identifying Factors Associated with Program Effectiveness.

    Science.gov (United States)

    Cragun, Deborah; Pal, Tuya; Vadaparampil, Susan T; Baldwin, Julie; Hampel, Heather; DeBate, Rita D

    2016-07-01

    Qualitative comparative analysis (QCA) was developed over 25 years ago to bridge the qualitative and quantitative research gap. Upon searching PubMed and the Journal of Mixed Methods Research, this review identified 30 original research studies that utilized QCA. Perceptions that QCA is complex and provides few relative advantages over other methods may be limiting QCA adoption. Thus, to overcome these perceptions, this article demonstrates how to perform QCA using data from fifteen institutions that implemented universal tumor screening (UTS) programs to identify patients at high risk for hereditary colorectal cancer. In this example, QCA revealed a combination of conditions unique to effective UTS programs. Results informed additional research and provided a model for improving patient follow-through after a positive screen.

  12. Hybrid programming model for implicit PDE simulations on multicore architectures

    KAUST Repository

    Kaushik, Dinesh K.

    2011-01-01

    The complexity of programming modern multicore processor based clusters is rapidly rising, with GPUs adding further demand for fine-grained parallelism. This paper analyzes the performance of the hybrid (MPI+OpenMP) programming model in the context of an implicit unstructured mesh CFD code. At the implementation level, the effects of cache locality, update management, work division, and synchronization frequency are studied. The hybrid model presents interesting algorithmic opportunities as well: the convergence of linear system solver is quicker than the pure MPI case since the parallel preconditioner stays stronger when hybrid model is used. This implies significant savings in the cost of communication and synchronization (explicit and implicit). Even though OpenMP based parallelism is easier to implement (with in a subdomain assigned to one MPI process for simplicity), getting good performance needs attention to data partitioning issues similar to those in the message-passing case. © 2011 Springer-Verlag.

  13. A hybrid DNA extraction method for the qualitative and quantitative assessment of bacterial communities from poultry production samples.

    Science.gov (United States)

    Rothrock, Michael J; Hiett, Kelli L; Gamble, John; Caudill, Andrew C; Cicconi-Hogan, Kellie M; Caporaso, J Gregory

    2014-12-10

    The efficacy of DNA extraction protocols can be highly dependent upon both the type of sample being investigated and the types of downstream analyses performed. Considering that the use of new bacterial community analysis techniques (e.g., microbiomics, metagenomics) is becoming more prevalent in the agricultural and environmental sciences and many environmental samples within these disciplines can be physiochemically and microbiologically unique (e.g., fecal and litter/bedding samples from the poultry production spectrum), appropriate and effective DNA extraction methods need to be carefully chosen. Therefore, a novel semi-automated hybrid DNA extraction method was developed specifically for use with environmental poultry production samples. This method is a combination of the two major types of DNA extraction: mechanical and enzymatic. A two-step intense mechanical homogenization step (using bead-beating specifically formulated for environmental samples) was added to the beginning of the "gold standard" enzymatic DNA extraction method for fecal samples to enhance the removal of bacteria and DNA from the sample matrix and improve the recovery of Gram-positive bacterial community members. Once the enzymatic extraction portion of the hybrid method was initiated, the remaining purification process was automated using a robotic workstation to increase sample throughput and decrease sample processing error. In comparison to the strict mechanical and enzymatic DNA extraction methods, this novel hybrid method provided the best overall combined performance when considering quantitative (using 16S rRNA qPCR) and qualitative (using microbiomics) estimates of the total bacterial communities when processing poultry feces and litter samples.

  14. Dynamic Modeling and Simulation of a Switched Reluctance Motor in a Series Hybrid Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Siavash Sadeghi

    2010-04-01

    Full Text Available Dynamic behavior analysis of electric motors is required in order to accuratelyevaluate the performance, energy consumption and pollution level of hybrid electricvehicles. Simulation tools for hybrid electric vehicles are divided into steady state anddynamic models. Tools with steady-state models are useful for system-level analysiswhereas tools that utilize dynamic models give in-depth information about the behavior ofsublevel components. For the accurate prediction of hybrid electric vehicle performance,dynamic modeling of the motor and other components is necessary. Whereas the switchedreluctance machine is well suited for electric and hybrid electric vehicles, due to the simpleand rugged construction, low cost, and ability to operate over a wide speed range atconstant power, in this paper dynamic performance of the switched reluctance motor for eseries hybrid electric vehicles is investigated. For this purpose a switched reluctance motorwith its electrical drive is modeld and simulated first, and then the other components of aseries hybrid electric vehicle, such as battery, generator, internal combusion engine, andgearbox, are designed and linked with the electric motor. Finally a typical series hybridelectric vehicle is simulated for different drive cycles. The extensive simulation results showthe dynamic performance of SRM, battery, fuel consumption, and emissions.

  15. MARIKA - A model revision system using qualitative analysis of simulations. [of human orientation system

    Science.gov (United States)

    Groleau, Nicolas; Frainier, Richard; Colombano, Silvano; Hazelton, Lyman; Szolovits, Peter

    1993-01-01

    This paper describes portions of a novel system called MARIKA (Model Analysis and Revision of Implicit Key Assumptions) to automatically revise a model of the normal human orientation system. The revision is based on analysis of discrepancies between experimental results and computer simulations. The discrepancies are calculated from qualitative analysis of quantitative simulations. The experimental and simulated time series are first discretized in time segments. Each segment is then approximated by linear combinations of simple shapes. The domain theory and knowledge are represented as a constraint network. Incompatibilities detected during constraint propagation within the network yield both parameter and structural model alterations. Interestingly, MARIKA diagnosed a data set from the Massachusetts Eye and Ear Infirmary Vestibular Laboratory as abnormal though the data was tagged as normal. Published results from other laboratories confirmed the finding. These encouraging results could lead to a useful clinical vestibular tool and to a scientific discovery system for space vestibular adaptation.

  16. E324 Simulation of Turbulent Channel Flow Using a RANS/LES Hybrid Model

    OpenAIRE

    半場, 藤弘; Fujihiro, Hamba; 東大生研; Institute of Industrial Science, University of Tokyo

    2004-01-01

    A RANS/LES hybrid simulation of a channel flow at Reτ=5000 was carried out using the Smagorinsky model. It is known that some hybrid simulations including the detached eddy simulation have a common defect: the mean velocity profile has a mismatch between the RANS and LES regions due to a steep gradient near the interface. New filtering for the velocity was introduced to improve the mean velocity profile. It was shown that this method increases the intensity of the normal velocity component in...

  17. Qualitative Analysis and Numerical Simulation of Equations of the Standard Cosmological Model: $\\Lambda\

    CERN Document Server

    Ignat'ev, Yurii

    2016-01-01

    On the basis of qualitative analysis of the system of differential equations of the standard cosmological model it is shown that in the case of zero cosmological constant this system has a stable center corresponding to zero values of potential and its derivative at infinity. Thus, the cosmological model based on single massive classical scalar field in infinite future would give a flat Universe. The carried out numerical simulation of the dynamic system corresponding to the system of Einstein - Klein - Gordon equations showed that at great times of the evolution the invariant cosmological acceleration has an oscillating character and changes from $-2$ (braking), to $+1$ (acceleration). Average value of the cosmological acceleration is negative and is equal to $-1/2$. Oscillations of the cosmological acceleration happen on the background of rapidly falling Hubble constant. In the case of nonzero value of the cosmological constant depending on its value there are possible three various qualitative behavior typ...

  18. Qualitative and Quantitative Analysis of Flower Pigments in Chocolate Cosmos, Cosmos atrosanguineus, and its Hybrids.

    Science.gov (United States)

    Amamiya, Kotarou; Iwashina, Tsukasa

    2016-01-01

    Two major anthocyanins, cyanidin 3-O-glucoside and 3-O-rutinoside, were isolated from the black flowers of Cosmos atrosanguineus cultivar 'Choco Mocha', together with three minor anthocyanins, cyanidin 3-O-malonylglucoside, pelargonidin 3-O-glucoside and 3-O-rutinoside. A chalcone, butein 4'-O-glucoside and three minor flavanones were isolated from the red flowers of C. atrosanguineis x C. sulphureus cultivar 'Rouge Rouge'. The anthocyanins and chalcone accumulation of cultivar 'Choco Mocha' and its hybrid cultivars 'Brown Rouge', 'Forte Rouge', 'Rouge Rouge' and 'Noel Rouge' was surveyed by quantitative HPLC. Total anthocyanins of black flower cultivars 'Choco Mocha' and 'Brown Rouge' were 3-4-folds higher than that of the red flower cultivar 'Noel Rouge'. On the other hand, total chalcone of 'Noel Rouge' was 10-77-folds higher compared with those of other cultivars, 'Brown Rouge', 'Forte Rouge' and 'Rouge Rouge'. It was shown that the flower color variations from red to black of Chocolate Cosmos and its hybrids are due to the difference in the relative amounts of anthocyanins and chalcone.

  19. Qualitative assessment of simulation-based training for pediatric trauma resuscitation.

    Science.gov (United States)

    Burke, Rita V; Demeter, Natalie E; Goodhue, Catherine J; Roesly, Heather; Rake, Alyssa; Young, L Caulette; Chang, Todd P; Cleek, Elizabeth; Morton, Inge; Upperman, Jeffrey S; Jensen, Aaron R

    2017-05-01

    Effective teamwork is critical in the trauma bay, although there is a lack of consensus related to optimal training for these skills. We implemented in situ trauma simulations with debriefing as a possible training methodology to improve team-oriented skills. Focus groups were conducted with multidisciplinary clinicians who respond to trauma activations. The focus group questions were intended to elicit discussion on the clinicians' experiences during trauma activations and simulations with an emphasis on confidence, leadership, cooperation, communication, and opportunities for improvement. Thematic content analysis was conducted using Atlas.ti analytical software. Ten focus groups were held with a total of 55 clinicians. Qualitative analysis of focus group feedback revealed the following selected themes: characteristics of a strong leader during a trauma, factors impacting trauma team members' confidence, and effective communication as a key component during trauma response. Participants recommended continued simulations to enhance trauma team trust and efficiency. Clinicians responding to pediatric trauma resuscitations valued the practice they received during trauma simulations and supported the continuation of the simulations to improve trauma activation teamwork and communication. Findings will inform the development of future simulation-based training programs to improve teamwork, confidence, and communication between trauma team members. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Test and numerical simulation of a new type of hybrid control technique

    Institute of Scientific and Technical Information of China (English)

    Meng Qingli; Zhang Minzheng; Cheng Dong

    2005-01-01

    In this paper, a new hybrid control technique, based on a combination of base-isolation and semi-active variable stiffness/damping in a superstructure, is presented. To illustrate the efficiency of the proposed control system, model tests on a mini-electromagnetic shaking table and a numerical simulation were performed. The test and numerical calculation results indicate that this new hybrid control mode with additional damping and smaller additional stiffness can achieve a better control efficiency.

  1. Selection of a Planning Horizon for a Hybrid Microgrid Using Simulated Wind Forecasts

    Science.gov (United States)

    2014-12-01

    Craparo Dashi I. Singham Naval Postgraduate School 1411 Cunningham Road Monterey, CA, 93943 USA ABSTRACT Hybrid microgrids containing renewable energy ...produced is at least as great as the total load. Energy is produced by generators, wind turbines, purchases from the commercial grid, and discharge of the...A PLANNING HORIZON FOR A HYBRID MICROGRID USING SIMULATED WIND FORECASTS Mumtaz Karatas Turkish Naval Academy Tuzla, Istanbul, 34942, TURKEY Emily M

  2. Dynamic Particle Weight Remapping in Hybrid PIC Hall-effect Thruster Simulation

    Science.gov (United States)

    2015-05-01

    International Electric Propulsion Conference and 6th Nano-satellite Symposium Hyogo-Kobe, Japan July 410, 2015 Robert Martin∗ ERC Incorporated, Huntsville...Algorithms, . 8Koo, J. and Martin, R., Pseudospectral model for hybrid PIC Hall -eect thruster simulation, 34th Int. Electric Propul- sion Conf...Paper 3. DATES COVERED (From - To) May 2015-July 2015 4. TITLE AND SUBTITLE Dynamic Particle Weight Remapping in Hybrid PIC Hall -effect Thruster

  3. Lower-Hybrid Drift Instability Saturation Mechanisms in One-Dimensional Simulations,

    Science.gov (United States)

    1980-09-19

    The linear properties and saturation mechanisms of the lower-hybrid drift instability have been investigated using a one-dimensional particle-hybrid simulation. For low drift velocities (V sub d much less than V sub ti), ion trapping and current relaxation (V sub d approaches limit of 0) are competing processes for stabilization. If the relative electron-ion drift velocity is kept constant in time , ion trapping causes

  4. An efficient algorithm for the stochastic simulation of the hybridization of DNA to microarrays

    Directory of Open Access Journals (Sweden)

    Laurenzi Ian J

    2009-12-01

    Full Text Available Abstract Background Although oligonucleotide microarray technology is ubiquitous in genomic research, reproducibility and standardization of expression measurements still concern many researchers. Cross-hybridization between microarray probes and non-target ssDNA has been implicated as a primary factor in sensitivity and selectivity loss. Since hybridization is a chemical process, it may be modeled at a population-level using a combination of material balance equations and thermodynamics. However, the hybridization reaction network may be exceptionally large for commercial arrays, which often possess at least one reporter per transcript. Quantification of the kinetics and equilibrium of exceptionally large chemical systems of this type is numerically infeasible with customary approaches. Results In this paper, we present a robust and computationally efficient algorithm for the simulation of hybridization processes underlying microarray assays. Our method may be utilized to identify the extent to which nucleic acid targets (e.g. cDNA will cross-hybridize with probes, and by extension, characterize probe robustnessusing the information specified by MAGE-TAB. Using this algorithm, we characterize cross-hybridization in a modified commercial microarray assay. Conclusions By integrating stochastic simulation with thermodynamic prediction tools for DNA hybridization, one may robustly and rapidly characterize of the selectivity of a proposed microarray design at the probe and "system" levels. Our code is available at http://www.laurenzi.net.

  5. Hybrid simulation of whistler excitation by electron beams in two-dimensional non-periodic domains

    Energy Technology Data Exchange (ETDEWEB)

    Woodroffe, J.R., E-mail: woodrofj@erau.edu; Streltsov, A.V., E-mail: streltsa@erau.edu

    2014-11-01

    We present a two-dimensional hybrid fluid-PIC scheme for the simulation of whistler wave excitation by relativistic electron beams. This scheme includes a number of features which are novel to simulations of this type, including non-periodic boundary conditions and fresh particle injection. Results from our model suggest that non-periodicity of the simulation domain results in the development of fundamentally different wave characteristics than are observed in periodic domains.

  6. Charaterizing the O+ ion plume from Hybrid simulations: comparison to MAVEN observations

    Science.gov (United States)

    Modolo, R.; Leblanc, F.; Chaufray, J. Y.; Leclercq, L.; Esteban-Hernandez, R.; Curry, S.; Dong, Y.; Brain, D. A.; Bowers, C.; Luhmann, J. G.; McFadden, J. P.; Halekas, J. S.; Espley, J. R.; Connerney, J. E. P.; Jakosky, B. M.

    2015-12-01

    MAVEN observations show a substantial plume-like distribution of escaping ions from the Martian atmosphere. It represents an important ion escape channel with large fluxes (Brain et al, 2015; Dong et al, 2015, Curry et al, 2015). Such structure is organized by the solar wind convection electric field and it is located in the MSE northward hemisphere. Global hybrid models (eg Modolo et al, 2005, 2012; Kallio et al, 2006; Brecht et al, 2006) reproduce nicely this plume. To further characterize this population, hybrid simulations have been performed with upstream solar wind conditions observed by MAVEN. Simulation results along the spacecraft track present signatures of high energetic O+ ions similar to MAVEN measurements. Comparison of simulated 3D distribution functions of this population are compared to STATIC and SWIA observations. Moreover a comparison of hybrid results with statistical ion fluxes maps derived from MAVEN (Dong et al, 2015; Brain et al, 2015) have been conducted and a reasonable agreement is found .

  7. Strategy and gaps for modeling, simulation, and control of hybrid systems

    Energy Technology Data Exchange (ETDEWEB)

    Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Garcia, Humberto E. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hovsapian, Rob [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kinoshita, Robert [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mesina, George L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bragg-Sitton, Shannon M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Boardman, Richard D. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-04-01

    The purpose of this report is to establish a strategy for modeling and simulation of candidate hybrid energy systems. Modeling and simulation is necessary to design, evaluate, and optimize the system technical and economic performance. Accordingly, this report first establishes the simulation requirements to analysis candidate hybrid systems. Simulation fidelity levels are established based on the temporal scale, real and synthetic data availability or needs, solution accuracy, and output parameters needed to evaluate case-specific figures of merit. Accordingly, the associated computational and co-simulation resources needed are established; including physical models when needed, code assembly and integrated solutions platforms, mathematical solvers, and data processing. This report first attempts to describe the figures of merit, systems requirements, and constraints that are necessary and sufficient to characterize the grid and hybrid systems behavior and market interactions. Loss of Load Probability (LOLP) and effective cost of Effective Cost of Energy (ECE), as opposed to the standard Levelized Cost of Electricty (LCOE), are introduced as technical and economical indices for integrated energy system evaluations. Financial assessment methods are subsequently introduced for evaluation of non-traditional, hybrid energy systems. Algorithms for coupled and iterative evaluation of the technical and economic performance are subsequently discussed. This report further defines modeling objectives, computational tools, solution approaches, and real-time data collection and processing (in some cases using real test units) that will be required to model, co-simulate, and optimize; (a) an energy system components (e.g., power generation unit, chemical process, electricity management unit), (b) system domains (e.g., thermal, electrical or chemical energy generation, conversion, and transport), and (c) systems control modules. Co-simulation of complex, tightly coupled

  8. Simulation of the performance of a hybrid ventilation system in different climates

    Energy Technology Data Exchange (ETDEWEB)

    Charvat, P.; Jicha, M. [Brno Univ. of Technology, Brno (Czech Republic). Faculty of Mechanical Engineering; Niachou, A.; Santamouris, M. [National and Kapodistrian Univ. of Athens, Athens (Greece)

    2005-07-01

    Four different concepts of hybrid ventilation systems for 4 climates in Europe have been developed within the Framework of the European Union project called Residential Hybrid Ventilation (RESHYVENT). This study involved computational simulations to examine the performance of the hybrid ventilation system for a moderate climate in an urban environment under various climatic conditions. A hybrid ventilation system refers to a ventilation system that uses natural driving forces as long as possible and which switches to mechanical forces when needed. It therefore minimizes energy consumption while maintaining good indoor air quality and thermal comfort for occupants. The RESHYVENT hybrid ventilation system consists of a self-regulating air inlet, DC fan, motorized damper, flow meter, central control unit, carbon dioxide sensors and ductwork. If natural driving forces are not sufficient, the fan engages and its speed adjusts to match the demanded flow rate. This paper presents a case study in which the TRNSYS type 15 software package was used with the TRNFlow air flow network module to simulate natural driving forces such as wind and buoyancy in an apartment building situated in an urban canyon. Results were obtained for a specific geometry, occupancy scheme and other factors. The study showed that the hybrid ventilation system was able to maintain required indoor air quality regardless of weather conditions. As such, it was better than the natural ventilation system and holds promise for use in office and residential buildings. The complexity of hybrid and natural ventilation systems is due to the fact that air flow rates depend greatly on climatic conditions. Therefore, simulations must consider thermal and air flow models. Experiments conducted at a demonstration house in Brno, Czech Republic show that the RESHYVENT hybrid ventilation system could maintain the level of carbon dioxide concentration in rooms below 1200 ppm. refs., 7 tabs., 3 figs.

  9. Qualitative simulation of bathymetric changes due to reservoir sedimentation: A Japanese case study.

    Science.gov (United States)

    Bilal, Ahmed; Dai, Wenhong; Larson, Magnus; Beebo, Qaid Naamo; Xie, Qiancheng

    2017-01-01

    Sediment-dynamics modeling is a useful tool for estimating a dam's lifespan and its cost-benefit analysis. Collecting real data for sediment-dynamics analysis from conventional field survey methods is both tedious and expensive. Therefore, for most rivers, the historical record of data is either missing or not very detailed. Available data and existing tools have much potential and may be used for qualitative prediction of future bathymetric change trend. This study shows that proxy approaches may be used to increase the spatiotemporal resolution of flow data, and hypothesize the river cross-sections and sediment data. Sediment-dynamics analysis of the reach of the Tenryu River upstream of Sakuma Dam in Japan was performed to predict its future bathymetric changes using a 1D numerical model (HEC-RAS). In this case study, only annually-averaged flow data and the river's longitudinal bed profile at 5-year intervals were available. Therefore, the other required data, including river cross-section and geometry and sediment inflow grain sizes, had to be hypothesized or assimilated indirectly. The model yielded a good qualitative agreement, with an R2 (coefficient of determination) of 0.8 for the observed and simulated bed profiles. A predictive simulation demonstrated that the useful life of the dam would end after the year 2035 (±5 years), which is in conformity with initial detailed estimates. The study indicates that a sediment-dynamic analysis can be performed even with a limited amount of data. However, such studies may only assess the qualitative trends of sediment dynamics.

  10. Qualitative and Quantitative Evaluation of Blob-Based Time-of-Flight PET Image Reconstruction in Hybrid Brain PET/MR Imaging.

    Science.gov (United States)

    Leemans, Eva L; Kotasidis, Fotis; Wissmeyer, Michael; Garibotto, Valentina; Zaidi, Habib

    2015-10-01

    Many neurological diseases affect small structures in the brain and, as such, reliable visual evaluation and accurate quantification are required. Recent technological developments made the clinical use of hybrid positron emission tomography/magnetic resonance (PET/MR) systems possible, providing both functional and anatomical information in a single imaging session. Nevertheless, there is a trade-off between spatial resolution and image quality (contrast and noise), which is dictated mainly by the chosen acquisition and reconstruction protocols. Image reconstruction algorithms using spherical symmetric basis functions (blobs) for image representation have a number of additional parameters that impact both the qualitative and quantitative image characteristics. Hence, a detailed investigation of the blob-based reconstruction characteristics using different parameters is needed to achieve optimal reconstruction results. This work evaluated the impact of a range of blob parameters on image quality and quantitative accuracy of brain PET images acquired on the Ingenuity Time-of-Flight (TOF) PET/MR system. Two different phantoms were used to simulate brain imaging applications. Image contrast and noise characteristics were assessed using an image quality phantom. Quantitative performance in a clinical setting was investigated using the Hoffman 3D brain phantom at various count levels. Furthermore, the visual quality of four clinical studies was scored blindly by two experienced physicians to qualitatively evaluate the influence of different reconstruction protocols, hereby providing indications on parameters producing the best image quality. Quantitative evaluation using the image quality phantom showed that larger basis function radii result in lower contrast recovery (∼2%) and lower variance levels (∼15%). The brain phantom and clinical studies confirmed these observations since lower contrast was seen between anatomical structures. High and low count statistics

  11. Hybrid TS fuzzy modelling and simulation for chaotic Lorenz system

    Institute of Scientific and Technical Information of China (English)

    Li De-Quan

    2006-01-01

    The projection of the chaotic attractor observed from the Lorenz system in the X-Z plane is like a butterfly, hence the classical Lorenz system is widely known as the butterfly attractor, and has served as a prototype model for studying chaotic behaviour since it was coined. In this work we take one step further to investigate some fundamental dynamic behaviours of a novel hybrid Takagi-Sugeno (TS) fuzzy Lorenz-type system, which is essentially derived from the delta-operator-based TS fuzzy modelling for complex nonlinear systems, and contains the original Lorenz system of continuous-time TS fuzzy form as a special case. By simply and appropriately tuning the additional parametric perturbations in the two-rule hybrid TS fuzzy Lorenz-type system, complex (two-wing) butterfly attractors observed from this system in the three dimensional (3D) X-Y-Z space are created, which have not yet been reported in the literature, and the forming mechanism of the compound structures have been numerically investigated.

  12. A hybrid method for flood simulation in small catchments combining hydrodynamic and hydrological techniques

    Science.gov (United States)

    Bellos, Vasilis; Tsakiris, George

    2016-09-01

    The study presents a new hybrid method for the simulation of flood events in small catchments. It combines a physically-based two-dimensional hydrodynamic model and the hydrological unit hydrograph theory. Unit hydrographs are derived using the FLOW-R2D model which is based on the full form of two-dimensional Shallow Water Equations, solved by a modified McCormack numerical scheme. The method is tested at a small catchment in a suburb of Athens-Greece for a storm event which occurred in February 2013. The catchment is divided into three friction zones and unit hydrographs of 15 and 30 min are produced. The infiltration process is simulated by the empirical Kostiakov equation and the Green-Ampt model. The results from the implementation of the proposed hybrid method are compared with recorded data at the hydrometric station at the outlet of the catchment and the results derived from the fully hydrodynamic model FLOW-R2D. It is concluded that for the case studied, the proposed hybrid method produces results close to those of the fully hydrodynamic simulation at substantially shorter computational time. This finding, if further verified in a variety of case studies, can be useful in devising effective hybrid tools for the two-dimensional flood simulations, which are lead to accurate and considerably faster results than those achieved by the fully hydrodynamic simulations.

  13. A hybrid approach to simulate multiple photon scattering in X-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Freud, N. [CNDRI, Laboratory of Nondestructive Testing using Ionizing Radiations, INSA-Lyon Scientific and Technical University, Bat. Antoine de Saint-Exupery, 20, avenue Albert Einstein, 69621 Villeurbanne Cedex (France)]. E-mail: nicolas.freud@insa-lyon.fr; Letang, J.-M. [CNDRI, Laboratory of Nondestructive Testing using Ionizing Radiations, INSA-Lyon Scientific and Technical University, Bat. Antoine de Saint-Exupery, 20, avenue Albert Einstein, 69621 Villeurbanne Cedex (France); Babot, D. [CNDRI, Laboratory of Nondestructive Testing using Ionizing Radiations, INSA-Lyon Scientific and Technical University, Bat. Antoine de Saint-Exupery, 20, avenue Albert Einstein, 69621 Villeurbanne Cedex (France)

    2005-01-01

    A hybrid simulation approach is proposed to compute the contribution of scattered radiation in X- or {gamma}-ray imaging. This approach takes advantage of the complementarity between the deterministic and probabilistic simulation methods. The proposed hybrid method consists of two stages. Firstly, a set of scattering events occurring in the inspected object is determined by means of classical Monte Carlo simulation. Secondly, this set of scattering events is used as a starting point to compute the energy imparted to the detector, with a deterministic algorithm based on a 'forced detection' scheme. For each scattering event, the probability for the scattered photon to reach each pixel of the detector is calculated using well-known physical models (form factor and incoherent scattering function approximations, in the case of Rayleigh and Compton scattering respectively). The results of the proposed hybrid approach are compared to those obtained with the Monte Carlo method alone (Geant4 code) and found to be in excellent agreement. The convergence of the results when the number of scattering events increases is studied. The proposed hybrid approach makes it possible to simulate the contribution of each type (Compton or Rayleigh) and order of scattering, separately or together, with a single PC, within reasonable computation times (from minutes to hours, depending on the number of pixels of the detector). This constitutes a substantial benefit, compared to classical simulation methods (Monte Carlo or deterministic approaches), which usually requires a parallel computing architecture to obtain comparable results.

  14. Qualitative evaluation of a standardized patient clinical simulation for nurse practitioner and pharmacy students.

    Science.gov (United States)

    Koo, Laura; Layson-Wolf, Cherokee; Brandt, Nicole; Hammersla, Margaret; Idzik, Shannon; Rocafort, P Tim; Tran, Deanna; Wilkerson, R Gentry; Windemuth, Brenda

    2014-11-01

    This article describes a qualitative evaluation of an interprofessional educational experience for nurse practitioner and pharmacy students using standardized patients and physicians role-playing physicians in clinical scenarios. This experience included the development of two clinical scenarios; training of standardized patients, providers, and faculty facilitators; pre-briefing preparation; partial facilitator prompting simulations; and facilitated debriefings. Forty-six students participated in the formative simulation. Small groups of students and faculty facilitators worked through two clinical scenarios that were based on the expected emergence of the patient-centered medical homes. The scenarios incorporated different interprofessional communication modes, including in-person, telephonic, and video-conferencing. Time-in/time-out debriefings were incorporated to provide guidance to students about how to engage in interprofessional collaboration. After completion of the scenarios, facilitated group debriefings allowed for reflection on communication strategies and roles. Immediately following the learning activity, 30 volunteer focus group participants provided comments anonymously in a semi-structured format. Conventional content analysis was used to identify overarching themes. Participants expressed improved understanding of individual roles, increased confidence, and a better sense of interprofessional support. The educational experience themes included the benefits of a realistic nature of the simulation and the need for improved student orientation to roles and expectations prior to the clinical simulations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Hybrid Reynolds-Averaged/Large Eddy Simulation of a Cavity Flameholder; Assessment of Modeling Sensitivities

    Science.gov (United States)

    Baurle, R. A.

    2015-01-01

    Steady-state and scale-resolving simulations have been performed for flow in and around a model scramjet combustor flameholder. The cases simulated corresponded to those used to examine this flowfield experimentally using particle image velocimetry. A variety of turbulence models were used for the steady-state Reynolds-averaged simulations which included both linear and non-linear eddy viscosity models. The scale-resolving simulations used a hybrid Reynolds-averaged / large eddy simulation strategy that is designed to be a large eddy simulation everywhere except in the inner portion (log layer and below) of the boundary layer. Hence, this formulation can be regarded as a wall-modeled large eddy simulation. This effort was undertaken to formally assess the performance of the hybrid Reynolds-averaged / large eddy simulation modeling approach in a flowfield of interest to the scramjet research community. The numerical errors were quantified for both the steady-state and scale-resolving simulations prior to making any claims of predictive accuracy relative to the measurements. The steady-state Reynolds-averaged results showed a high degree of variability when comparing the predictions obtained from each turbulence model, with the non-linear eddy viscosity model (an explicit algebraic stress model) providing the most accurate prediction of the measured values. The hybrid Reynolds-averaged/large eddy simulation results were carefully scrutinized to ensure that even the coarsest grid had an acceptable level of resolution for large eddy simulation, and that the time-averaged statistics were acceptably accurate. The autocorrelation and its Fourier transform were the primary tools used for this assessment. The statistics extracted from the hybrid simulation strategy proved to be more accurate than the Reynolds-averaged results obtained using the linear eddy viscosity models. However, there was no predictive improvement noted over the results obtained from the explicit

  16. Hybrid Modeling and Simulation of Automotive Supply Chain Network

    Directory of Open Access Journals (Sweden)

    Wen Wang

    2013-07-01

    Full Text Available According to the operation of automotive supply chain and the features of various simulation methods, we create and simulate a automotive supply chain network model with the core enterprise of two vehicle manufacturers, consisting of several parts suppliers, vehicle distributors and logistics service providers. On this basis of a conceptual model including the establishment of enterprise layer, business layer and operation layer, we establish a detailed model of the network system according to the network structure of automotive supply chain, the operation process and the internal business process of core enterprises; then we use System Dynamics (SD, Discrete Event Simulation (DES and Agent Based Modeling (ABM to describe the operating state of each node in the network model. We execute and analyze the simulation model of the whole network system described by Anylogic, using the results of the distributors’ inventory, inventory cost and customer’s satisfaction to prove the effectiveness of the model.

  17. A hybrid simulation approach for integrating safety behavior into construction planning: An earthmoving case study.

    Science.gov (United States)

    Goh, Yang Miang; Askar Ali, Mohamed Jawad

    2016-08-01

    One of the key challenges in improving construction safety and health is the management of safety behavior. From a system point of view, workers work unsafely due to system level issues such as poor safety culture, excessive production pressure, inadequate allocation of resources and time and lack of training. These systemic issues should be eradicated or minimized during planning. However, there is a lack of detailed planning tools to help managers assess the impact of their upstream decisions on worker safety behavior. Even though simulation had been used in construction planning, the review conducted in this study showed that construction safety management research had not been exploiting the potential of simulation techniques. Thus, a hybrid simulation framework is proposed to facilitate integration of safety management considerations into construction activity simulation. The hybrid framework consists of discrete event simulation (DES) as the core, but heterogeneous, interactive and intelligent (able to make decisions) agents replace traditional entities and resources. In addition, some of the cognitive processes and physiological aspects of agents are captured using system dynamics (SD) approach. The combination of DES, agent-based simulation (ABS) and SD allows a more "natural" representation of the complex dynamics in construction activities. The proposed hybrid framework was demonstrated using a hypothetical case study. In addition, due to the lack of application of factorial experiment approach in safety management simulation, the case study demonstrated sensitivity analysis and factorial experiment to guide future research.

  18. Thermodynamic Simulation of a Hybrid Pneumatic-Combustion Engine Concept

    Directory of Open Access Journals (Sweden)

    Yann Chamaillard

    2002-03-01

    Full Text Available Although internal combustion engines display high overall maximum global efficiencies, this potential cannot be fully exploited in automotive applications: in real conditions, the average engine load (and thus efficiency is quite low and the kinetic energy during a braking phase is lost. This work presents a new hybrid pneumatic-combustion engine and the associated thermodynamic cycles, which is able to store energy in the form of compressed air. This energy can be issued from a braking phase or from a combustion phase at low power. The potential energy from the air tank can then be restored to start the engine, or charge the engine at full load. The regenerative breaking and the suppression of the idling phases could provide an improvement in terms of fuel economy as high as 15% or more if combined with engine downsizing.

  19. Plasma simulation in a hybrid ion electric propulsion system

    Science.gov (United States)

    Jugroot, Manish; Christou, Alex

    2015-04-01

    An exciting possibility for the next generation of satellite technology is the microsatellite. These satellites, ranging from 10-500 kg, can offer advantages in cost, reduced risk, and increased functionality for a variety of missions. For station keeping and control of these satellites, a suitable compact and high efficiency thruster is required. Electrostatic propulsion provides a promising solution for microsatellite thrust due to their high specific impulse. The rare gas propellant is ionized into plasma and generates a beam of high speed ions by electrostatic processes. A concept explored in this work is a hybrid combination of dc ion engines and hall thrusters to overcome space-charge and lifetime limitations of current ion thruster technologies. A multiphysics space and time-dependent formulation was used to investigate and understand the underlying physical phenomena. Several regions and time scales of the plasma have been observed and will be discussed.

  20. Hybrid stochastic simulation of reaction-diffusion systems with slow and fast dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Strehl, Robert; Ilie, Silvana, E-mail: silvana@ryerson.ca [Department of Mathematics, Ryerson University, Toronto, Ontario M5B 2K3 (Canada)

    2015-12-21

    In this paper, we present a novel hybrid method to simulate discrete stochastic reaction-diffusion models arising in biochemical signaling pathways. We study moderately stiff systems, for which we can partition each reaction or diffusion channel into either a slow or fast subset, based on its propensity. Numerical approaches missing this distinction are often limited with respect to computational run time or approximation quality. We design an approximate scheme that remedies these pitfalls by using a new blending strategy of the well-established inhomogeneous stochastic simulation algorithm and the tau-leaping simulation method. The advantages of our hybrid simulation algorithm are demonstrated on three benchmarking systems, with special focus on approximation accuracy and efficiency.

  1. Hybrid particle-field molecular dynamics simulations for dense polymer systems.

    Science.gov (United States)

    Milano, Giuseppe; Kawakatsu, Toshihiro

    2009-06-07

    We propose a theoretical scheme for a hybrid simulation technique where self-consistent field theory and molecular dynamics simulation are combined (MD-SCF). We describe the detail of the main implementation issues on the evaluation of a smooth three-dimensional spatial density distribution and its special gradient based on the positions of particles. The treatments of our multiscale model system on an atomic scale or on a specific coarse-grained scale are carefully discussed. We perform a series of test simulations on this hybrid model system and compare the structural correlations on the atomic scale with those of classical MD simulations. The results are very encouraging and open a way to an efficient strategy that possess the main advantages common to the SCF and the atomistic approaches, while avoiding the disadvantages of each of the treatments.

  2. Modeling and Simulation of Renewable Hybrid Power System using Matlab Simulink Environment

    Directory of Open Access Journals (Sweden)

    Cristian Dragoş Dumitru

    2010-12-01

    Full Text Available The paper presents the modeling of a solar-wind-hydroelectric hybrid system in Matlab/Simulink environment. The application is useful for analysis and simulation of a real hybrid solar-wind-hydroelectric system connected to a public grid. Application is built on modular architecture to facilitate easy study of each component module influence. Blocks like wind model, solar model, hydroelectric model, energy conversion and load are implemented and the results of simulation are also presented. As an example, one of the most important studies is the behavior of hybrid system which allows employing renewable and variable in time energy sources while providing a continuous supply. Application represents a useful tool in research activity and also in teaching

  3. Dynamic Simulation of Carbonate Fuel Cell-Gas Turbine Hybrid Systems

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, R.A. (U. of California, Irvine, CA); Brouwer, J. (U. of California, Irvine, CA); Liese, E.A.; Gemmen, R.S.

    2006-04-01

    Hybrid fuel cell/gas turbine systems provide an efficient means of producing electricity from fossil fuels with ultra low emissions. However, there are many significant challenges involved in integrating the fuel cell with the gas turbine and other components of this type of system. The fuel cell and the gas turbine must maintain efficient operation and electricity production while protecting equipment during perturbations that may occur when the system is connected to the utility grid or in stand-alone mode. This paper presents recent dynamic simulation results from two laboratories focused on developing tools to aid in the design and dynamic analyses of hybrid fuel cell systems. The simulation results present the response of a carbonate fuel cell/gas turbine, or molten carbonate fuel cell/gas turbine, (MCFC/GT) hybrid system to a load demand perturbation. Initial results suggest that creative control strategies will be needed to ensure a flexible system with wide turndown and robust dynamic operation.

  4. Hybrid molecular-continuum simulations using smoothed dissipative particle dynamics.

    Science.gov (United States)

    Petsev, Nikolai D; Leal, L Gary; Shell, M Scott

    2015-01-28

    We present a new multiscale simulation methodology for coupling a region with atomistic detail simulated via molecular dynamics (MD) to a numerical solution of the fluctuating Navier-Stokes equations obtained from smoothed dissipative particle dynamics (SDPD). In this approach, chemical potential gradients emerge due to differences in resolution within the total system and are reduced by introducing a pairwise thermodynamic force inside the buffer region between the two domains where particles change from MD to SDPD types. When combined with a multi-resolution SDPD approach, such as the one proposed by Kulkarni et al. [J. Chem. Phys. 138, 234105 (2013)], this method makes it possible to systematically couple atomistic models to arbitrarily coarse continuum domains modeled as SDPD fluids with varying resolution. We test this technique by showing that it correctly reproduces thermodynamic properties across the entire simulation domain for a simple Lennard-Jones fluid. Furthermore, we demonstrate that this approach is also suitable for non-equilibrium problems by applying it to simulations of the start up of shear flow. The robustness of the method is illustrated with two different flow scenarios in which shear forces act in directions parallel and perpendicular to the interface separating the continuum and atomistic domains. In both cases, we obtain the correct transient velocity profile. We also perform a triple-scale shear flow simulation where we include two SDPD regions with different resolutions in addition to a MD domain, illustrating the feasibility of a three-scale coupling.

  5. Hybrid molecular-continuum simulations using smoothed dissipative particle dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Petsev, Nikolai D.; Leal, L. Gary; Shell, M. Scott [Department of Chemical Engineering, University of California at Santa Barbara, Santa Barbara, California 93106-5080 (United States)

    2015-01-28

    We present a new multiscale simulation methodology for coupling a region with atomistic detail simulated via molecular dynamics (MD) to a numerical solution of the fluctuating Navier-Stokes equations obtained from smoothed dissipative particle dynamics (SDPD). In this approach, chemical potential gradients emerge due to differences in resolution within the total system and are reduced by introducing a pairwise thermodynamic force inside the buffer region between the two domains where particles change from MD to SDPD types. When combined with a multi-resolution SDPD approach, such as the one proposed by Kulkarni et al. [J. Chem. Phys. 138, 234105 (2013)], this method makes it possible to systematically couple atomistic models to arbitrarily coarse continuum domains modeled as SDPD fluids with varying resolution. We test this technique by showing that it correctly reproduces thermodynamic properties across the entire simulation domain for a simple Lennard-Jones fluid. Furthermore, we demonstrate that this approach is also suitable for non-equilibrium problems by applying it to simulations of the start up of shear flow. The robustness of the method is illustrated with two different flow scenarios in which shear forces act in directions parallel and perpendicular to the interface separating the continuum and atomistic domains. In both cases, we obtain the correct transient velocity profile. We also perform a triple-scale shear flow simulation where we include two SDPD regions with different resolutions in addition to a MD domain, illustrating the feasibility of a three-scale coupling.

  6. A multi-scale code for flexible hybrid simulations

    CERN Document Server

    Leukkunen, L; Lopez-Acevedo, O

    2012-01-01

    Multi-scale computer simulations combine the computationally efficient classical algorithms with more expensive but also more accurate ab-initio quantum mechanical algorithms. This work describes one implementation of multi-scale computations using the Atomistic Simulation Environment (ASE). This implementation can mix classical codes like LAMMPS and the Density Functional Theory-based GPAW. Any combination of codes linked via the ASE interface however can be mixed. We also introduce a framework to easily add classical force fields calculators for ASE using LAMMPS, which also allows harnessing the full performance of classical-only molecular dynamics. Our work makes it possible to combine different simulation codes, quantum mechanical or classical, with great ease and minimal coding effort.

  7. Accelerated stochastic and hybrid methods for spatial simulations of reaction-diffusion systems

    OpenAIRE

    Rossinelli, D; Bayati, B; Koumoutsakos, P.

    2008-01-01

    Spatial distributions characterize the evolution of reaction-diffusion models of several physical, chemical, and biological systems. We present two novel algorithms for the efficient simulation of these models: Spatial т-Leaping (Sт -Leaping), employing a unified acceleration of the stochastic simulation of reaction and diffusion, and Hybrid т-Leaping (Hт-Leaping), combining a deterministic diffusion approximation with a т-Leaping acceleration of the stochastic reactions. The algorithms are v...

  8. An atomistic-continuum hybrid simulation of fluid flows over superhydrophobic surfaces

    OpenAIRE

    Li, Qiang; He, Guo-Wei

    2009-01-01

    Recent experiments have found that slip length could be as large as on the order of 1 μm for fluid flows over superhydrophobic surfaces. Superhydrophobic surfaces can be achieved by patterning roughness on hydrophobic surfaces. In the present paper, an atomistic-continuum hybrid approach is developed to simulate the Couette flows over superhydrophobic surfaces, in which a molecular dynamics simulation is used in a small region near the superhydrophobic surface where the continuum assumption i...

  9. Hybrid simulations : combining atomistic and coarse-grained force fields using virtual sites

    NARCIS (Netherlands)

    Rzepiela, Andrzej J.; Louhivuori, Martti; Peter, Christine; Marrink, Siewert J.

    2011-01-01

    Hybrid simulations, in which part of the system is represented at atomic resolution and the remaining part at a reduced, coarse-grained, level offer a powerful way to combine the accuracy associated with the atomistic force fields to the sampling speed obtained with coarse-grained (CG) potentials. I

  10. Dynamic Performance Comparison for MPPT-PV Systems using Hybrid Pspice/Matlab Simulation

    Science.gov (United States)

    Aouchiche, N.; Becherif, M.; HadjArab, A.; Aitcheikh, M. S.; Ramadan, H. S.; Cheknane, A.

    2016-10-01

    The power generated by solar photovoltaic (PV) module depends on the surrounding irradiance and temperature. This paper presents a hybrid Matlab™/Pspice™ simulation model of PV system, combined with Cadence software SLPS. The hybridization is performed in order to gain the advantages of both simulation tools such as accuracy and efficiency in both Pspice electronic circuit and Matlab™ mathematical modelling respectively. For this purpose, the PV panel and the boost converter are developed using Pspice™ and hybridized with the mathematical Matlab™ model of maximum power point method controller (MPPT) through SLPS. The main objective is verify the significance of using the proposed hybrid simulation techniques in comparing the different MPPT algorithms such as the perturbation and observation (P&O), incremental of conductance (Inc-Cond) and counter reaction voltage using pilot cell (Pilot-Cell). Various simulations are performed under different atmospheric conditions in order to evaluate the dynamic behaviour for the system under study in terms of stability, efficiency and rapidity.

  11. Simulation modeling of functional adaptive interference nulling for multibeam hybrid reflector antenna systems

    Science.gov (United States)

    Kartsan, I. N.; Tyapkin, V. N.; Dmitriev, D. D.; Goncharov, A. E.; Zelenkov, P. V.; Kovalev, I. V.

    2016-11-01

    This paper considers the simulation of adaptive nulling mechanism patterns in hybrid reflector antenna systems with a 19-element feed element, in which the radiation pattern is formed as a cluster. Incidents of broadband and narrowband interference are studied in the article.

  12. Hybrid Large-Eddy/Reynolds-Averaged Simulation of a Supersonic Cavity Using VULCAN

    Science.gov (United States)

    Quinlan, Jesse; McDaniel, James; Baurle, Robert A.

    2013-01-01

    Simulations of a supersonic recessed-cavity flow are performed using a hybrid large-eddy/Reynolds-averaged simulation approach utilizing an inflow turbulence recycling procedure and hybridized inviscid flux scheme. Calorically perfect air enters a three-dimensional domain at a free stream Mach number of 2.92. Simulations are performed to assess grid sensitivity of the solution, efficacy of the turbulence recycling, and the effect of the shock sensor used with the hybridized inviscid flux scheme. Analysis of the turbulent boundary layer upstream of the rearward-facing step for each case indicates excellent agreement with theoretical predictions. Mean velocity and pressure results are compared to Reynolds-averaged simulations and experimental data for each case and indicate good agreement on the finest grid. Simulations are repeated on a coarsened grid, and results indicate strong grid density sensitivity. Simulations are performed with and without inflow turbulence recycling on the coarse grid to isolate the effect of the recycling procedure, which is demonstrably critical to capturing the relevant shear layer dynamics. Shock sensor formulations of Ducros and Larsson are found to predict mean flow statistics equally well.

  13. Qualitative Analysis and Numerical Simulation of Equations of the Standard Cosmological Model

    CERN Document Server

    Ignat'ev, Yurii

    2016-01-01

    On the basis of qualitative theory of differential equations it is shown that dynamic system based on the system of Einstein - Klein - Gordon equations with regard to Friedman Universe has a stable center corresponding to zero values of scalar potential and its derivative at infinity. Thus, the cosmological model based on single massive classical scalar field in infinite future would give a flat Universe. The carried out numerical simulation of the dynamic system corresponding to the system of Einstein - Klein - Gordon equations showed that at great times of the evolution the invariant cosmological acceleration has a microscopic oscillating character ($T\\sim 2\\pi mt$), while macroscopic value of the cosmological acceleration varies from $+1$ at inflation stage after which if decreases fast to $-1/2$ (non-relativistic stage), and then slowly tends to $-1$ (ultrarelativistic stage).

  14. Modeling and Simulation for Hybrid of PV-Wind system

    Directory of Open Access Journals (Sweden)

    Maged N. F. Nashed

    2015-04-01

    Full Text Available The rising consumption rate of fossil fuels causes a significant pollution impact on the atmosphere, unwanted greenhouse gases has drawn worldwide attention towards renewable energy sources. Moreover, in recent year’s generation of electricity using the different types of renewable sources are specifically evaluated in the economical performance of the overall equipment. This paper focuses on the modeling and analysis of a Standalone Photovoltaic (PV- wind energy hybrid generation system under different conditions using MATLAB. The proposed system consists of two renewable sources i.e. wind and solar energy. Modeling of PV array and wind turbine is explained. The wind subsystem is equipped of an induction generator. In photovoltaic system, the variable DC output voltage is controlled using buck-boost converter for the MPPT. These two systems are combined to operate in parallel and the common bus collects the total energy from the wind and PV systems are uses it to the load and with change the load

  15. Sampling Enrichment toward Target Structures Using Hybrid Molecular Dynamics-Monte Carlo Simulations.

    Science.gov (United States)

    Yang, Kecheng; Różycki, Bartosz; Cui, Fengchao; Shi, Ce; Chen, Wenduo; Li, Yunqi

    2016-01-01

    Sampling enrichment toward a target state, an analogue of the improvement of sampling efficiency (SE), is critical in both the refinement of protein structures and the generation of near-native structure ensembles for the exploration of structure-function relationships. We developed a hybrid molecular dynamics (MD)-Monte Carlo (MC) approach to enrich the sampling toward the target structures. In this approach, the higher SE is achieved by perturbing the conventional MD simulations with a MC structure-acceptance judgment, which is based on the coincidence degree of small angle x-ray scattering (SAXS) intensity profiles between the simulation structures and the target structure. We found that the hybrid simulations could significantly improve SE by making the top-ranked models much closer to the target structures both in the secondary and tertiary structures. Specifically, for the 20 mono-residue peptides, when the initial structures had the root-mean-squared deviation (RMSD) from the target structure smaller than 7 Å, the hybrid MD-MC simulations afforded, on average, 0.83 Å and 1.73 Å in RMSD closer to the target than the parallel MD simulations at 310K and 370K, respectively. Meanwhile, the average SE values are also increased by 13.2% and 15.7%. The enrichment of sampling becomes more significant when the target states are gradually detectable in the MD-MC simulations in comparison with the parallel MD simulations, and provide >200% improvement in SE. We also performed a test of the hybrid MD-MC approach in the real protein system, the results showed that the SE for 3 out of 5 real proteins are improved. Overall, this work presents an efficient way of utilizing solution SAXS to improve protein structure prediction and refinement, as well as the generation of near native structures for function annotation.

  16. Hybrid airfoil design methods for full-scale ice accretion simulation

    Science.gov (United States)

    Saeed, Farooq

    The objective of this thesis is to develop a design method together with a design philosophy that allows the design of "subscale" or "hybrid" airfoils that simulate fullscale ice accretions. These subscale or hybrid airfoils have full-scale leading edges and redesigned aft-sections. A preliminary study to help develop a design philosophy for the design of hybrid airfoils showed that hybrid airfoils could be designed to simulate full-scale airfoil droplet-impingement characteristics and, therefore, ice accretion. The study showed that the primary objective in such a design should be to determine the aft section profile that provides the circulation necessary for simulating full-scale airfoil droplet-impingement characteristics. The outcome of the study, therefore, reveals circulation control as the main design variable. To best utilize this fact, this thesis describes two innovative airfoil design methods for the design of hybrid airfoils. Of the two design methods, one uses a conventional flap system while the other only suggests the use of boundary-layer control through slot-suction on the airfoil upper surface as a possible alternative for circulation control. The formulation of each of the two design methods is described in detail, and the results from each method are validated using wind-tunnel test data. The thesis demonstrates the capabilities of each method with the help of specific design examples highlighting their application potential. In particular, the flap-system based hybrid airfoil design method is used to demonstrate the design of a half-scale hybrid model of a full-scale airfoil that simulates full-scale ice accretion at both the design and off-design conditions. The full-scale airfoil used is representative of a scaled modern business-jet main wing section. The study suggests some useful advantages of using hybrid airfoils as opposed to full-scale airfoils for a better understanding of the ice accretion process and the related issues. Results

  17. A comparative study of leachate quality and biogas generation in simulated anaerobic and hybrid bioreactors.

    Science.gov (United States)

    Xu, Qiyong; Tian, Ying; Wang, Shen; Ko, Jae Hac

    2015-07-01

    Research has been conducted to compare leachate characterization and biogas generation in simulated anaerobic and hybrid bioreactor landfills with typical Chinese municipal solid waste (MSW). Three laboratory-scale reactors, an anaerobic (A1) and two hybrid bioreactors (C1 and C2), were constructed and operated for about 10months. The hybrid bioreactors were operated in an aerobic-anaerobic mode with different aeration frequencies by providing air into the upper layer of waste. Results showed that the temporary aeration into the upper layer aided methane generation by shortening the initial acidogenic phase because of volatile fatty acids (VFAs) reduction and pH increase. Chemical oxygen demand (COD) decreased faster in the hybrid bioreactors, but the concentrations of ammonia-nitrogen in the hybrid bioreactors were greater than those in the anaerobic control. Methanogenic conditions were established within 75d and 60d in C1 and C2, respectively. However, high aeration frequency led to the consumption of organic matters by aerobic degradation and resulted in reducing accumulative methane volume. The temporary aeration enhanced waste settlement and the settlement increased with increasing the frequency of aeration. Methane production was inhibited in the anaerobic control; however, the total methane generations from hybrid bioreactors were 133.4L/kgvs and 113.2L/kgvs. As for MSW with high content of food waste, leachate recirculation right after aeration stopped was not recommended due to VFA inhibition for methanogens.

  18. Formation of Compact Clusters from High Resolution Hybrid Cosmological Simulations

    CERN Document Server

    Richardson, Mark L A; Gray, William J

    2013-01-01

    The early Universe hosted a large population of small dark matter `minihalos' that were too small to cool and form stars on their own. These existed as static objects around larger galaxies until acted upon by some outside influence. Outflows, which have been observed around a variety of galaxies, can provide this influence in such a way as to collapse, rather than disperse the minihalo gas. Gray & Scannapieco performed an investigation in which idealized spherically-symmetric minihalos were struck by enriched outflows. Here we perform high-resolution cosmological simulations that form realistic minihalos, which we then extract to perform a large suite of simulations of outflow-minihalo interactions including non-equilibrium chemical reactions. In all models, the shocked minihalo forms molecules through non-equilibrium reactions, and then cools to form dense chemically homogenous clumps of star-forming gas. The formation of these high-redshift clusters will be observable with the next generation of telesc...

  19. Integrated Plasma Simulation of Lower Hybrid Current Drive in Tokamaks

    Science.gov (United States)

    Bonoli, P. T.; Wright, J. C.; Harvey, R. W.; Batchelor, D. B.; Berry, L. A.; Kessel, C. E.; Jardin, S. C.

    2012-03-01

    It has been shown in Alcator C-Mod that the onset time for sawteeth can be delayed significantly (up to 0.5 s) relative to ohmically heated plasmas, through the injection of off-axis LH current drive power [1]. We are simulating these experiments using the Integrated Plasma Simulator (IPS) [2], where the driven LH current density profiles are computed using a ray tracing component (GENRAY) and Fokker Planck code (CQL3D) [3] that are run in a tightly coupled time advance. The background plasma is evolved using the TSC transport code with the Porcelli sawtooth model [4]. Predictions of the driven LH current profiles will be compared with simpler ``reduced'' models for LHCD such as the LSC code which is implemented in TSC and which is also invoked within the IPS. [4pt] [1] C. E. Kessel et al, Bull. of the Am. Phys. Soc. 53, Poster PP6.00074 (2008). [0pt] [2] D. Batchelor et al, Journal of Physics: Conf. Series 125, 012039 (2008). [0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Meeting on Simulation and Modeling of Therm. Plasmas, Montreal, Canada (1992). [0pt] [4] S. C. Jardin et al, J. Comp. Phys. 66, 481 (1986).

  20. A comparative study of leachate quality and biogas generation in simulated anaerobic and hybrid bioreactors

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Qiyong; Tian, Ying; Wang, Shen; Ko, Jae Hac, E-mail: jaehacko@pkusz.edu.cn

    2015-07-15

    Highlights: • Temporary aeration shortened the initial acid inhibition phase for methanogens. • COD decreased faster in the hybrid bioreactor than that in the anaerobic control. • Methane generations from hybrid bioreactors were 133.4 L/kg{sub vs} and 113.2 L/kg{sub vs}. • MSW settlement increased with increasing the frequency of intermittent aeration. - Abstract: Research has been conducted to compare leachate characterization and biogas generation in simulated anaerobic and hybrid bioreactor landfills with typical Chinese municipal solid waste (MSW). Three laboratory-scale reactors, an anaerobic (A1) and two hybrid bioreactors (C1 and C2), were constructed and operated for about 10 months. The hybrid bioreactors were operated in an aerobic–anaerobic mode with different aeration frequencies by providing air into the upper layer of waste. Results showed that the temporary aeration into the upper layer aided methane generation by shortening the initial acidogenic phase because of volatile fatty acids (VFAs) reduction and pH increase. Chemical oxygen demand (COD) decreased faster in the hybrid bioreactors, but the concentrations of ammonia–nitrogen in the hybrid bioreactors were greater than those in the anaerobic control. Methanogenic conditions were established within 75 d and 60 d in C1 and C2, respectively. However, high aeration frequency led to the consumption of organic matters by aerobic degradation and resulted in reducing accumulative methane volume. The temporary aeration enhanced waste settlement and the settlement increased with increasing the frequency of aeration. Methane production was inhibited in the anaerobic control; however, the total methane generations from hybrid bioreactors were 133.4 L/kg{sub vs} and 113.2 L/kg{sub vs}. As for MSW with high content of food waste, leachate recirculation right after aeration stopped was not recommended due to VFA inhibition for methanogens.

  1. Hybrid simulation research on formation mechanism of tungsten nanostructure induced by helium plasma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Atsushi M., E-mail: ito.atsushi@nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Takayama, Arimichi; Oda, Yasuhiro [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Tamura, Tomoyuki; Kobayashi, Ryo; Hattori, Tatsunori; Ogata, Shuji [Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan); Ohno, Noriyasu; Kajita, Shin [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Yajima, Miyuki [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Noiri, Yasuyuki [Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Yoshimoto, Yoshihide [University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Saito, Seiki [Kushiro National College of Technology, Kushiro, Hokkaido 084-0916 (Japan); Takamura, Shuichi [Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota 470-0392 (Japan); Murashima, Takahiro [Tohoku University, 6-3, Aramaki-Aza-Aoba, Aoba-Ward, Sendai 980-8578 (Japan); Miyamoto, Mitsutaka [Shimane University, Matsue, Shimane 690-8504 (Japan); Nakamura, Hiroaki [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-08-15

    The generation of tungsten fuzzy nanostructure by exposure to helium plasma is one of the important problems for the use of tungsten material as divertor plates in nuclear fusion reactors. In the present paper, the formation mechanisms of the helium bubble and the tungsten fuzzy nanostructure were investigated by using several simulation methods. We proposed the four-step process which is composed of penetration step, diffusion and agglomeration step, helium bubble growth step, and fuzzy nanostructure formation step. As the fourth step, the formation of the tungsten fuzzy nanostructure was successfully reproduced by newly developed hybrid simulation combining between molecular dynamics and Monte-Carlo method. The formation mechanism of tungsten fuzzy nanostructure observed by the hybrid simulation is that concavity and convexity of the surface are enhanced by the bursting of helium bubbles in the region around the concavity.

  2. A hybrid local/non-local framework for the simulation of damage and fracture

    KAUST Repository

    Azdoud, Yan

    2014-01-01

    Recent advances in non-local continuum models, notably peridynamics, have spurred a paradigm shift in solid mechanics simulation by allowing accurate mathematical representation of singularities and discontinuities. This doctoral work attempts to extend the use of this theory to a community more familiar with local continuum models. In this communication, a coupling strategy - the morphing method -, which bridges local and non-local models, is presented. This thesis employs the morphing method to ease use of the non-local model to represent problems with failure-induced discontinuities. First, we give a quick review of strategies for the simulation of discrete degradation, and suggest a hybrid local/non-local alternative. Second, we present the technical concepts involved in the morphing method and evaluate the quality of the coupling. Third, we develop a numerical tool for the simulation of the hybrid model for fracture and damage and demonstrate its capabilities on numerical model examples

  3. Modeling and Simulation of Metallurgical Process Based on Hybrid Petri Net

    Science.gov (United States)

    Ren, Yujuan; Bao, Hong

    2016-11-01

    In order to achieve the goals of energy saving and emission reduction of iron and steel enterprises, an increasing number of modeling and simulation technologies are used to research and analyse metallurgical production process. In this paper, the basic principle of Hybrid Petri net is used to model and analyse the Metallurgical Process. Firstly, the definition of Hybrid Petri Net System of Metallurgical Process (MPHPNS) and its modeling theory are proposed. Secondly, the model of MPHPNS based on material flow is constructed. The dynamic flow of materials and the real-time change of each technological state in metallurgical process are simulated vividly by using this model. The simulation process can implement interaction between the continuous event dynamic system and the discrete event dynamic system at the same level, and play a positive role in the production decision.

  4. Optimal design of supply chain network under uncertainty environment using hybrid analytical and simulation modeling approach

    Science.gov (United States)

    Chiadamrong, N.; Piyathanavong, V.

    2017-04-01

    Models that aim to optimize the design of supply chain networks have gained more interest in the supply chain literature. Mixed-integer linear programming and discrete-event simulation are widely used for such an optimization problem. We present a hybrid approach to support decisions for supply chain network design using a combination of analytical and discrete-event simulation models. The proposed approach is based on iterative procedures until the difference between subsequent solutions satisfies the pre-determined termination criteria. The effectiveness of proposed approach is illustrated by an example, which shows closer to optimal results with much faster solving time than the results obtained from the conventional simulation-based optimization model. The efficacy of this proposed hybrid approach is promising and can be applied as a powerful tool in designing a real supply chain network. It also provides the possibility to model and solve more realistic problems, which incorporate dynamism and uncertainty.

  5. Hybrid simulation research on formation mechanism of tungsten nanostructure induced by helium plasma irradiation

    Science.gov (United States)

    Ito, Atsushi M.; Takayama, Arimichi; Oda, Yasuhiro; Tamura, Tomoyuki; Kobayashi, Ryo; Hattori, Tatsunori; Ogata, Shuji; Ohno, Noriyasu; Kajita, Shin; Yajima, Miyuki; Noiri, Yasuyuki; Yoshimoto, Yoshihide; Saito, Seiki; Takamura, Shuichi; Murashima, Takahiro; Miyamoto, Mitsutaka; Nakamura, Hiroaki

    2015-08-01

    The generation of tungsten fuzzy nanostructure by exposure to helium plasma is one of the important problems for the use of tungsten material as divertor plates in nuclear fusion reactors. In the present paper, the formation mechanisms of the helium bubble and the tungsten fuzzy nanostructure were investigated by using several simulation methods. We proposed the four-step process which is composed of penetration step, diffusion and agglomeration step, helium bubble growth step, and fuzzy nanostructure formation step. As the fourth step, the formation of the tungsten fuzzy nanostructure was successfully reproduced by newly developed hybrid simulation combining between molecular dynamics and Monte-Carlo method. The formation mechanism of tungsten fuzzy nanostructure observed by the hybrid simulation is that concavity and convexity of the surface are enhanced by the bursting of helium bubbles in the region around the concavity.

  6. Recovery act. Development of design and simulation tool for hybrid geothermal heat pump system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shaojie [ClimateMaster, Inc., Oklahoma City, OK (United States); Ellis, Dan [ClimateMaster, Inc., Oklahoma City, OK (United States)

    2014-05-29

    The ground source heat pump (GSHP) system is one of the most energy efficient HVAC technologies in the current market. However, the heat imbalance may degrade the ability of the ground loop heat exchanger (GLHX) to absorb or reject heat. The hybrid GSHP system, which combines a geothermal well field with a supplemental boiler or cooling tower, can balance the loads imposed on the ground loop heat exchangers to minimize its size while retaining superior energy efficiency. This paper presents a recent simulation-based study with an intention to compare multiple common control strategies used in hybrid GSHP systems, including fixed setpoint, outside air reset, load reset, and wetbulb reset. A small office in Oklahoma City conditioned by a hybrid GSHP system was simulated with the latest version of eQUEST 3.7[1]. The simulation results reveal that the hybrid GSHP system has the excellent capability to meet the cooling and heating setpoints during the occupied hours, balance thermal loads on the ground loop, as well as improve the thermal comfort of the occupants with the undersized well field.

  7. Development of a hybrid simulation course to reduce central line infections.

    Science.gov (United States)

    Clapper, Timothy

    2012-05-01

    Clinical educators are continually looking at ways to effectively deliver large amounts of information to their learners. Whether as a part of pre-course work or as a separate phase of training, there are numerous benefits to making information available to learners before conducting sessions that allow the learners to practice the skills. Hybrid courses consist of a mixture of online and on-site instruction and offer a viable option for clinical educators to consider, especially when their intended audience consists of thousands of learners. This article describes the experiences of a medical simulation center and the use of a hybrid curriculum technique to reduce central line infections.

  8. Hybrid Reynolds-Averaged/Large-Eddy Simulations of a Coaxial Supersonic Free-Jet Experiment

    Science.gov (United States)

    Baurle, Robert A.; Edwards, Jack R.

    2010-01-01

    Reynolds-averaged and hybrid Reynolds-averaged/large-eddy simulations have been applied to a supersonic coaxial jet flow experiment. The experiment was designed to study compressible mixing flow phenomenon under conditions that are representative of those encountered in scramjet combustors. The experiment utilized either helium or argon as the inner jet nozzle fluid, and the outer jet nozzle fluid consisted of laboratory air. The inner and outer nozzles were designed and operated to produce nearly pressure-matched Mach 1.8 flow conditions at the jet exit. The purpose of the computational effort was to assess the state-of-the-art for each modeling approach, and to use the hybrid Reynolds-averaged/large-eddy simulations to gather insight into the deficiencies of the Reynolds-averaged closure models. The Reynolds-averaged simulations displayed a strong sensitivity to choice of turbulent Schmidt number. The initial value chosen for this parameter resulted in an over-prediction of the mixing layer spreading rate for the helium case, but the opposite trend was observed when argon was used as the injectant. A larger turbulent Schmidt number greatly improved the comparison of the results with measurements for the helium simulations, but variations in the Schmidt number did not improve the argon comparisons. The hybrid Reynolds-averaged/large-eddy simulations also over-predicted the mixing layer spreading rate for the helium case, while under-predicting the rate of mixing when argon was used as the injectant. The primary reason conjectured for the discrepancy between the hybrid simulation results and the measurements centered around issues related to the transition from a Reynolds-averaged state to one with resolved turbulent content. Improvements to the inflow conditions were suggested as a remedy to this dilemma. Second-order turbulence statistics were also compared to their modeled Reynolds-averaged counterparts to evaluate the effectiveness of common turbulence closure

  9. An isentropic and sigma coordinate hybrid numerical model - Model development and some initial tests. [for atmospheric simulations

    Science.gov (United States)

    Uccellini, L. W.; Johnson, D. R.; Schlesinger, R. E.

    1979-01-01

    A solution is presented for matching boundary conditions across the interface of an isentropic and sigma coordinate hybrid model. A hybrid model based on the flux form of the primitive equations is developed which allows direct vertical exchange between the model domains, satisfies conservation principles with respect to transport processes, and maintains a smooth transition across the interface without need for artificial adjustment or parameterization schemes. The initial hybrid model simulations of a jet streak propagating in a zonal channel are used to test the feasibility of the hybrid model approach. High efficiency of the hybrid model is demonstrated.

  10. Hybrid Network Simulation for the ATLAS Trigger and Data Acquisition (TDAQ) System

    CERN Document Server

    Bonaventura, Matias Alejandro; The ATLAS collaboration; Castro, Rodrigo Daniel; Foguelman, Daniel Jacob

    2015-01-01

    The poster shows the ongoing research in the ATLAS TDAQ group in collaboration with the University of Buenos Aires in the area of hybrid data network simulations. he Data Network and Processing Cluster filters data in real-time, achieving a rejection factor in the order of 40000x and has real-time latency constrains. The dataflow between the processing units (TPUs) and Readout System (ROS) presents a “TCP Incast”-type network pathology which TCP cannot handle it efficiently. A credits system is in place which limits rate of queries and reduces latency. This large computer network, and the complex dataflow has been modelled and simulated using a PowerDEVS, a DEVS-based simulator. The simulation has been validated and used to produce what-if scenarios in the real network. Network Simulation with Hybrid Flows: Speedups and accuracy, combined • For intensive network traffic, Discrete Event simulation models (packet-level granularity) soon becomes prohibitive: Too high computing demands. • Fluid Flow simul...

  11. Modelling and Simulation of System Dynamics of Hybrid-Driven Precision Press

    Institute of Scientific and Technical Information of China (English)

    LI Yonggang; ZHANG Ce; MENG Caifang; SONG Yimin

    2005-01-01

    Different from conventional mechanical systems with single degree of freedom (DOF), the main idea of the system of hybrid-driven precision press is to combine the motion of a constant speed motor with a servomotor via a two-DOF mechanism to provide flexible output. In order to make the feasibility clear, this paper studies theoretically the dynamic characteristics of this hybrid-driven mechanical system.Firstly,the dynamics model of the whole electromechanical system is set up by combining dynamic equations of DC motors with those of two-DOF nine-bar mechanism deduced by the Lagrange′s formula. Secondly through the numerical solution with the fourth Runge-Kutta, computer simulation about the dynamics is done, which shows that the designed and optimized hybrid-driven precision press is feasible in theory. These provide theoretical basis for later experimental research.

  12. Simulations of ionospheric turbulence produced by HF heating near the upper hybrid layer

    Science.gov (United States)

    Najmi, A.; Eliasson, B.; Shao, X.; Milikh, G. M.; Papadopoulos, K.

    2016-06-01

    Heating of the ionosphere by high-frequency (HF), ordinary (O) mode electromagnetic waves can excite magnetic field-aligned density striations, associated with upper and lower hybrid turbulence and electron heating. We have used Vlasov simulations in one spatial and two velocity dimensions to study the induced turbulence in the presence of striations when the O-mode pump is mode converted to large-amplitude upper hybrid oscillations trapped in a striation. Parametric processes give rise to upper and lower hybrid turbulence, as well as to large amplitude, short wavelength electron Bernstein waves. The latter excite stochastic electron heating when their amplitudes exceed a threshold for stochasticity, leading to a rapid increase of the electron temperature by several thousands of kelvin. The results have relevance for high-latitude heating experiments.

  13. Electric and hybrid electric vehicle study utilizing a time-stepping simulation

    Science.gov (United States)

    Schreiber, Jeffrey G.; Shaltens, Richard K.; Beremand, Donald G.

    1992-01-01

    The applicability of NASA's advanced power technologies to electric and hybrid vehicles was assessed using a time-stepping computer simulation to model electric and hybrid vehicles operating over the Federal Urban Driving Schedule (FUDS). Both the energy and power demands of the FUDS were taken into account and vehicle economy, range, and performance were addressed simultaneously. Results indicate that a hybrid electric vehicle (HEV) configured with a flywheel buffer energy storage device and a free-piston Stirling convertor fulfills the emissions, fuel economy, range, and performance requirements that would make it acceptable to the consumer. It is noted that an assessment to determine which of the candidate technologies are suited for the HEV application has yet to be made. A proper assessment should take into account the fuel economy and range, along with the driveability and total emissions produced.

  14. Numerical simulations for the effiency improvement of hybrid dye-microcrystalline silicon pin-solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Burdorf, Sven; Bauer, Gottfried Heinrich; Brueggemann, Rudolf [Institut fuer Physik, Carl von Ossietzky Universitaet, Oldenburg (Germany)

    2011-07-01

    Hybrid solar cells consisting of dye sensitizers incorporated in the i-layer of microcrystalline silicon pin solar cell have been proposed and even recently processed. The dye sensitizer molecules are embedded in the matrix and enhance the overall absorption of the dye-matrix system due to their high absorption coefficient in the spectral range interesting for photovoltaic applications. However, the charge transport properties of dyes are quite poor. Microcrystalline silicon on the other hand has acceptable charge transport properties, while the absorption, given a layer thickness in the micron range, is relatively poor. This contribution investigates the effiency improvement of hybrid dye-microcrystalline solar cells compared to pure microcrystalline solar cells by simulation. The results indicate that, under optimal conditions, the effiency can be improved by more than 20 % compared to a pure microcrystalline silicon cell. The thickness reduction for the hybrid system can be as large as 50 % for the same effiency.

  15. Characteristics of Effective Simulation (Preclinical) Teachers as Identified by Dental Students: A Qualitative Study.

    Science.gov (United States)

    McAndrew, Maureen; Mucciolo, Thomas W; Jahangiri, Leila

    2016-11-01

    The aim of this qualitative research study was to identify and categorize criteria for simulation teacher quality preferences as reported by dental students. Second-year dental students at New York University College of Dentistry in 2015 were given a two-question, open-ended survey asking what qualities they liked most and least in a simulation or preclinical teacher. Responses were collected until data saturation was reached. Key words in the responses were identified and coded based on similar relationships and then were grouped into defined categories. A total of 168 respondents out of the target group of 363 students (46.3%) provided 1,062 written comments. Three core themes-character, competence, and communication-emerged from 16 defined categories, which were validated using references from the educational literature. The theme of character encompassed eight of the defined categories (motivation, available, caring, patience, professionalism, empathy, fairness, and happiness) and accounted for 50% of the total student responses. The theme of competence comprised five categories (expertise, knowledgeable, efficient, skillful, and effective) and represented 34% of all responses. The communication theme covered the remaining three categories (feedback, approachable, and interpersonal communication) and contained 17% of the responses. Positive and negative comments in the category of motivation accounted for 11.2% of all student responses. Expertise was the next highest category with 9.3% of the responses, followed closely by 9.1% in the category of available. Among these students, the top five attributes of simulation teachers were motivation, expertise, available, caring, and feedback. While the study did not attempt to correlate these findings with improved student performance, the results can be used in the development of assessment tools for faculty and targeted faculty development programs.

  16. Development of a software platform for a plug-in hybrid electric vehicle simulator

    Science.gov (United States)

    Karlis, Athanasios; Bibeau, Eric; Zanetel, Paul; Lye, Zelon

    2012-03-01

    Electricity use for transportation has had limited applications because of battery storage range issues, although many recent successful demonstrations of electric vehicles have been achieved. Renewable biofuels such as biodiesel and bioethanol also contribute only a small percentage of the overall energy mix for mobility. Recent advances in hybrid technologies have significantly increased vehicle efficiencies. More importantly, hybridization now allows a significant reduction in battery capacity requirements compared to pure electric vehicles, allowing electricity to be used in the overall energy mix in the transportation sector. This paper presents an effort made to develop a Plug-in Hybrid Electric Vehicle (PHEV) platform that can act as a comprehensive alternative energy vehicle simulator. Its goal is to help in solving the pressing needs of the transportation sector, both in terms of contributing data to aid policy decisions for reducing fossil fuel use, and to support research in this important area. The Simulator will allow analysing different vehicle configurations, and control strategies with regards to renewable and non-renewable fuel and electricity sources. The simulation platform models the fundamental aspects of PHEV components, that is, process control, heat transfer, chemical reactions, thermodynamics and fluid properties. The outcomes of the Simulator are: (i) determining the optimal combination of fuels and grid electricity use, (ii) performing greenhouse gas calculations based on emerging protocols being developed, and (iii) optimizing the efficient and proper use of renewable energy sources in a carbon constrained world.

  17. Simulation of Hybrid Photovoltaic Solar Assisted Loop Heat Pipe/Heat Pump System

    Directory of Open Access Journals (Sweden)

    Nannan Dai

    2017-02-01

    Full Text Available A hybrid photovoltaic solar assisted loop heat pipe/heat pump (PV-SALHP/HP water heater system has been developed and numerically studied. The system is the combination of loop heat pipe (LHP mode and heat pump (HP mode, and the two modes can be run separately or compositely according to the weather conditions. The performances of independent heat pump (HP mode and hybrid loop heat pipe/heat pump (LHP/HP mode were simulated and compared. Simulation results showed that on typical sunny days in spring or autumn, using LHP/HP mode could save 40.6% power consumption than HP mode. In addition, the optimal switchover from LHP mode to HP mode was analyzed in different weather conditions for energy saving and the all-year round operating performances of the system were also simulated. The simulation results showed that hybrid LHP/HP mode should be utilized to save electricity on sunny days from March to November and the system can rely on LHP mode alone without any power consumption in July and August. When solar radiation and ambient temperature are low in winter, HP mode should be used

  18. Hybrid simulation models for data-intensive systems

    CERN Document Server

    Barisits, Martin

    Data-intensive systems are used to access and store massive amounts of data by combining the storage resources of multiple data-centers, usually deployed all over the world, in one system. This enables users to utilize these massive storage capabilities in a simple and efficient way. However, with the growth of these systems it becomes a hard problem to estimate the effects of modifications to the system, such as data placement algorithms or hardware upgrades, and to validate these changes for potential side effects. This thesis addresses the modeling of operational data-intensive systems and presents a novel simulation model which estimates the performance of system operations. The running example used throughout this thesis is the data-intensive system Rucio, which is used as the data man- agement system of the ATLAS experiment at CERN’s Large Hadron Collider. Existing system models in literature are not applicable to data-intensive workflows, as they only consider computational workflows or make assumpti...

  19. Fast garment simulation with aid of hybrid bones

    Institute of Scientific and Technical Information of China (English)

    吴博; 陈寅; 徐凯; 程志全; 熊岳山

    2015-01-01

    A data-driven method was proposed to realistically animate garments on human poses in reduced space. Firstly, a gradient based method was extended to generate motion sequences and garments were simulated on the sequences as our training data. Based on the examples, the proposed method can fast output realistic garments on new poses. Our framework can be mainly divided into offline phase and online phase. During the offline phase, based on linear blend skinning (LBS), rigid bones and flex bones were estimated for human bodies and garments, respectively. Then, rigid bone weight maps on garment vertices were learned from examples. In the online phase, new human poses were treated as input to estimate rigid bone transformations. Then, both rigid bones and flex bones were used to drive garments to fit the new poses. Finally, a novel formulation was also proposed to efficiently deal with garment-body penetration. Experiments manifest that our method is fast and accurate. The intersection artifacts are fast removed and final garment results are quite realistic.

  20. Multivariable Robust Control of a Simulated Hybrid Solid Oxide Fuel Cell Gas Turbine Plant

    Energy Technology Data Exchange (ETDEWEB)

    Tsai A, Banta L, Tucker D

    2010-08-01

    This work presents a systematic approach to the multivariable robust control of a hybrid fuel cell gas turbine plant. The hybrid configuration under investigation built by the National Energy Technology Laboratory comprises a physical simulation of a 300kW fuel cell coupled to a 120kW auxiliary power unit single spool gas turbine. The public facility provides for the testing and simulation of different fuel cell models that in turn help identify the key difficulties encountered in the transient operation of such systems. An empirical model of the built facility comprising a simulated fuel cell cathode volume and balance of plant components is derived via frequency response data. Through the modulation of various airflow bypass valves within the hybrid configuration, Bode plots are used to derive key input/output interactions in transfer function format. A multivariate system is then built from individual transfer functions, creating a matrix that serves as the nominal plant in an H{sub {infinity}} robust control algorithm. The controller’s main objective is to track and maintain hybrid operational constraints in the fuel cell’s cathode airflow, and the turbo machinery states of temperature and speed, under transient disturbances. This algorithm is then tested on a Simulink/MatLab platform for various perturbations of load and fuel cell heat effluence. As a complementary tool to the aforementioned empirical plant, a nonlinear analytical model faithful to the existing process and instrumentation arrangement is evaluated and designed in the Simulink environment. This parallel task intends to serve as a building block to scalable hybrid configurations that might require a more detailed nonlinear representation for a wide variety of controller schemes and hardware implementations.

  1. Hybrid annealing using a quantum simulator coupled to a classical computer

    CERN Document Server

    Graß, Tobias

    2016-01-01

    Finding the global minimum in a rugged potential landscape is a computationally hard task, often equivalent to relevant optimization problems. Simulated annealing is a computational technique which explores the configuration space by mimicking thermal noise. By slow cooling, it freezes the system in a low-energy configuration, but the algorithm often gets stuck in local minima. In quantum annealing, the thermal noise is replaced by controllable quantum fluctuations, and the technique can be implemented in modern quantum simulators. However, quantum-adiabatic schemes become prohibitively slow in the presence of quasidegeneracies. Here we propose a strategy which combines ideas from simulated annealing and quantum annealing. In such hybrid algorithm, the outcome of a quantum simulator is processed on a classical device. While the quantum simulator explores the configuration space by repeatedly applying quantum fluctuations and performing projective measurements, the classical computer evaluates each configurati...

  2. RAD sequencing and genomic simulations resolve hybrid origins within North American Canis

    Science.gov (United States)

    Rutledge, L. Y.; Devillard, S.; Boone, J. Q.; Hohenlohe, P. A.; White, B. N.

    2015-01-01

    Top predators are disappearing worldwide, significantly changing ecosystems that depend on top-down regulation. Conflict with humans remains the primary roadblock for large carnivore conservation, but for the eastern wolf (Canis lycaon), disagreement over its evolutionary origins presents a significant barrier to conservation in Canada and has impeded protection for grey wolves (Canis lupus) in the USA. Here, we use 127 235 single-nucleotide polymorphisms (SNPs) identified from restriction-site associated DNA sequencing (RAD-seq) of wolves and coyotes, in combination with genomic simulations, to test hypotheses of hybrid origins of Canis types in eastern North America. A principal components analysis revealed no evidence to support eastern wolves, or any other Canis type, as the product of grey wolf × western coyote hybridization. In contrast, simulations that included eastern wolves as a distinct taxon clarified the hybrid origins of Great Lakes-boreal wolves and eastern coyotes. Our results support the eastern wolf as a distinct genomic cluster in North America and help resolve hybrid origins of Great Lakes wolves and eastern coyotes. The data provide timely information that will shed new light on the debate over wolf conservation in eastern North America. PMID:26156129

  3. Safer@home-Simulation and training: the study protocol of a qualitative action research design.

    Science.gov (United States)

    Wiig, Siri; Guise, Veslemøy; Anderson, Janet; Storm, Marianne; Lunde Husebø, Anne Marie; Testad, Ingelin; Søyland, Elsa; Moltu, Kirsti L

    2014-07-29

    While it is predicted that telecare and other information and communication technology (ICT)-assisted services will have an increasingly important role in future healthcare services, their implementation in practice is complex. For implementation of telecare to be successful and ensure quality of care, sufficient training for staff (healthcare professionals) and service users (patients) is fundamental. Telecare training has been found to have positive effects on attitudes to, sustained use of, and outcomes associated with telecare. However, the potential contribution of training in the adoption, quality and safety of telecare services is an under-investigated research field. The overall aim of this study is to develop and evaluate simulation-based telecare training programmes to aid the use of videophone technology in elderly home care. Research-based training programmes will be designed for healthcare professionals, service users and next of kin, and the study will explore the impact of training on adoption, quality and safety of new telecare services. The study has a qualitative action research design. The research will be undertaken in close collaboration with a multidisciplinary team consisting of researchers and managers and clinical representatives from healthcare services in two Norwegian municipalities, alongside experts in clinical education and simulation, as well as service user (patient) representatives. The qualitative methods used involve focus group interviews, semistructured interviews, observation and document analysis. To ensure trustworthiness in the data analysis, we will apply member checks and analyst triangulation; in addition to providing contextual and sample description to allow for evaluation of transferability of our results to other contexts and groups. The study is approved by the Norwegian Social Science Data Services. The study is based on voluntary participation and informed written consent. Informants can withdraw at any point in

  4. Hybrid systems modelling and simulation in DESTECS: a co-simulation approach

    NARCIS (Netherlands)

    Ni, Yunyun; Broenink, Johannes F.; Klumpp, M.

    2012-01-01

    This paper introduces the modelling methodology and tooling in DESTECS (www.destecs.org) - Design Support and Tooling for Embedded Control Software - project as a novel modelling approach for hybrid systems from an executable model perspective. It provides a top-level structure for the system model

  5. A hybrid SPH/N-body method for star cluster simulations

    CERN Document Server

    Hubber, D A; Smith, R; Goodwin, S P

    2013-01-01

    We present a new hybrid Smoothed Particle Hydrodynamics (SPH)/N-body method for modelling the collisional stellar dynamics of young clusters in a live gas background. By deriving the equations of motion from Lagrangian mechanics we obtain a formally conservative combined SPH/N-body scheme. The SPH gas particles are integrated with a 2nd order Leapfrog, and the stars with a 4th order Hermite scheme. Our new approach is intended to bridge the divide between the detailed, but expensive, full hydrodynamical simulations of star formation, and pure N-body simulations of gas-free star clusters. We have implemented this hybrid approach in the SPH code SEREN (Hubber et al. 2011) and perform a series of simple tests to demonstrate the fidelity of the algorithm and its conservation properties. We investigate and present resolution criteria to adequately resolve the density field and to prevent strong numerical scattering effects. Future developments will include a more sophisticated treatment of binaries.

  6. An hybrid RANS/LES model for simulation of complex turbulent flow

    Institute of Scientific and Technical Information of China (English)

    魏群; 陈红勋; 马峥

    2016-01-01

    A non-linear eddy viscosity model (NLEVM) and a scalable hybrid Reynolds averaged Navier-Stokes/ large eddy simula- tion (RANS/LES) strategy are developed to improve the capability of the eddy viscosity model (EVM) to simulate complex flows featuring separations and unsteady motions. To study the performance of the NLEVM, numerical simulations around S809 airfoil are carried out and the results show that the NLEVM performs much better when a large separation occurs. Calculated results of the flow around a triangular cylinder show that the NLEVM can improve the precision of the flow fields to some extents, but the error is still considerable, and the small turbulence structures can not be clearly captured as the EVM. Whereas the scalable hybrid RANS/LES model based on the NLEVM is fairly effective on resolving the turbulent structures and can give more satisfactory predictions of the flow fields.

  7. Hybrid Decomposition Method in Parallel Molecular Dynamics Simulation Based on SMP Cluster Architecture

    Institute of Scientific and Technical Information of China (English)

    WANG Bing; SHU Jiwu; ZHENG Weimin; WANG Jinzhao; CHEN Min

    2005-01-01

    A hybrid decomposition method for molecular dynamics simulations was presented, using simultaneously spatial decomposition and force decomposition to fit the architecture of a cluster of symmetric multi-processor (SMP) nodes. The method distributes particles between nodes based on the spatial decomposition strategy to reduce inter-node communication costs. The method also partitions particle pairs within each node using the force decomposition strategy to improve the load balance for each node. Simulation results for a nucleation process with 4 000 000 particles show that the hybrid method achieves better parallel performance than either spatial or force decomposition alone, especially when applied to a large scale particle system with non-uniform spatial density.

  8. A hybrid hopfield network-simulated annealing approach for frequency assignment in satellite communications systems.

    Science.gov (United States)

    Salcedo-Sanz, Sancho; Santiago-Mozos, Ricardo; Bousoño-Calzón, Carlos

    2004-04-01

    A hybrid Hopfield network-simulated annealing algorithm (HopSA) is presented for the frequency assignment problem (FAP) in satellite communications. The goal of this NP-complete problem is minimizing the cochannel interference between satellite communication systems by rearranging the frequency assignment, for the systems can accommodate the increasing demands. The HopSA algorithm consists of a fast digital Hopfield neural network which manages the problem constraints hybridized with a simulated annealing which improves the quality of the solutions obtained. We analyze the problem and its formulation, describing and discussing the HopSA algorithm and solving a set of benchmark problems. The results obtained are compared with other existing approaches in order to show the performance of the HopSA approach.

  9. Full Wave Simulation of Integrated Circuits Using Hybrid Numerical Methods

    Science.gov (United States)

    Tan, Jilin

    Transmission lines play an important role in digital electronics, and in microwave and millimeter-wave circuits. Analysis, modeling, and design of transmission lines are critical to the development of the circuitry in the chip, subsystem, and system levels. In the past several decays, at the EM modeling level, the quasi-static approximation has been widely used due to its great simplicity. As the clock rates increase, the inter-connect effects such as signal delay, distortion, dispersion, reflection, and crosstalk, limit the performance of microwave systems. Meanwhile, the quasi-static approach loses its validity for some complex system structures. Since the successful system design of the PCB, MCM, and the chip packaging, rely very much on the computer aided EM level modeling and simulation, many new methods have been developed, such as the full wave approach, to guarantee the successful design. Many difficulties exist in the rigorous EM level analysis. Some of these include the difficulties in describing the behavior of the conductors with finite thickness and finite conductivity, the field singularity, and the arbitrary multilayered multi-transmission lines structures. This dissertation concentrates on the full wave study of the multi-conductor transmission lines with finite conductivity and finite thickness buried in an arbitrary lossy multilayered environment. Two general approaches have been developed. The first one is the integral equation method in which the dyadic Green's function for arbitrary layered media has been correctly formulated and has been tested both analytically and numerically. By applying this method, the double layered high dielectric permitivitty problem and the heavy dielectrical lossy problem in multilayered media in the CMOS circuit design have been solved. The second approach is the edge element method. In this study, the correct functional for the two dimensional propagation problem has been successfully constructed in a rigorous way

  10. Efficient parabolic evaluation of coupling terms in hybrid quantum/classical simulations

    Energy Technology Data Exchange (ETDEWEB)

    Bastida, Adolfo, E-mail: bastida@um.es [Departamento de Quimica Fisica, Facultad de Quimica, Universidad de Murcia, 30100 Murcia (Spain); Soler, Miguel Angel; Zuniga, Jose; Requena, Alberto [Departamento de Quimica Fisica, Facultad de Quimica, Universidad de Murcia, 30100 Murcia (Spain); Miguel, Beatriz [Departamento de Ingenieria Quimica y Ambiental, Universidad Politecnica de Cartagena, 30203 Cartagena (Spain)

    2009-03-30

    A parabolic interpolation function of time is proposed to evaluate the non-adiabatic coupling matrix elements and the adiabatic energies at intermediate times within the classical time integration interval in hybrid quantum/classical simulations. The accuracy and the computational efficiency of this parabolic approximation are illustrated by carrying out a numerical application to the well-studied vibrational relaxation of I{sub 2} in liquid xenon.

  11. Using Hybrid Simulation/Analytical Queueing Networks to Capacitate USAF Air Mobility Command Passenger Terminals

    Science.gov (United States)

    2012-03-01

    airports’ terminal processing facilities again utilizing the AACC /IATA criteria. This method , however, received much criticism for various fundamental flaws...networks in the literature are limited, so a method for using DES to adjust for ar- rival time-dependency in QNA is developed. Second, beyond quality of...terminal in particular, using a hybrid of simulation and analytical methods . The challenge, then, is to determine the optimal capacity given estimated

  12. A robust method for handling low density regions in hybrid simulations for collisionless plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Amano, Takanobu, E-mail: amano@eps.s.u-tokyo.ac.jp; Higashimori, Katsuaki; Shirakawa, Keisuke

    2014-10-15

    A robust method to handle vacuum and near vacuum regions in hybrid simulations for space and astrophysical plasmas is presented. The conventional hybrid simulation model dealing with kinetic ions and a massless charge-neutralizing electron fluid is known to be susceptible to numerical instability due to divergence of the whistler-mode wave dispersion, as well as division-by-density operation in regions of low density. Consequently, a pure vacuum region is not allowed to exist in the simulation domain unless some ad hoc technique is used. To resolve this difficulty, an alternative way to introduce finite electron inertia effect is proposed. Contrary to the conventional method, the proposed one introduces a correction to the electric field rather than the magnetic field. It is shown that the generalized Ohm's law correctly reduces to Laplace's equation in a vacuum which therefore does not involve any numerical problems. In addition, a variable ion-to-electron mass ratio is introduced to reduce the phase velocity of high frequency whistler waves at low density regions so that the stability condition is always satisfied. It is demonstrated that the proposed model is able to handle near vacuum regions generated as a result of nonlinear self-consistent development of the system, as well as pure vacuum regions set up at the initial condition, without losing the advantages of the standard hybrid code.

  13. Hybrid simulation of scatter intensity in industrial cone-beam computed tomography

    Science.gov (United States)

    Thierry, R.; Miceli, A.; Hofmann, J.; Flisch, A.; Sennhauser, U.

    2009-01-01

    A cone-beam computed tomography (CT) system using a 450 kV X-ray tube has been developed to challenge the three-dimensional imaging of parts of the automotive industry in short acquisition time. Because the probability of detecting scattered photons is high regarding the energy range and the area of detection, a scattering correction becomes mandatory for generating reliable images with enhanced contrast detectability. In this paper, we present a hybrid simulator for the fast and accurate calculation of the scattering intensity distribution. The full acquisition chain, from the generation of a polyenergetic photon beam, its interaction with the scanned object and the energy deposit in the detector is simulated. Object phantoms can be spatially described in form of voxels, mathematical primitives or CAD models. Uncollided radiation is treated with a ray-tracing method and scattered radiation is split into single and multiple scattering. The single scattering is calculated with a deterministic approach accelerated with a forced detection method. The residual noisy signal is subsequently deconvoluted with the iterative Richardson-Lucy method. Finally the multiple scattering is addressed with a coarse Monte Carlo (MC) simulation. The proposed hybrid method has been validated on aluminium phantoms with varying size and object-to-detector distance, and found in good agreement with the MC code Geant4. The acceleration achieved by the hybrid method over the standard MC on a single projection is approximately of three orders of magnitude.

  14. Video conferencing versus telephone calls for team work across hospitals: a qualitative study on simulated emergencies

    Directory of Open Access Journals (Sweden)

    Hagen Oddvar

    2009-11-01

    Full Text Available Abstract Background Teamwork is important for patient care and outcome in emergencies. In rural areas, efficient communication between rural hospitals and regional trauma centers optimise decisions and treatment of trauma patients. Little is known on potentials and effects of virtual team to team cooperation between rural and regional trauma teams. Methods We adapted a video conferencing (VC system to the work process between multidisciplinary teams responsible for trauma as well as medical emergencies between one rural and one regional (university hospital. We studied how the teams cooperated during simulated critical scenarios, and compared VC with standard telephone communication. We used qualitative observations and interviews to evaluate results. Results The team members found VC to be a useful tool during emergencies and for building "virtual emergency teams" across distant hospitals. Visual communication combined with visual patient information is superior to information gained during ordinary telephone calls, but VC may also cause interruptions in the local teamwork. Conclusion VC can improve clinical cooperation and decision processes in virtual teams during critical patient care. Such team interaction requires thoughtful organisation, training, and new rules for communication.

  15. A digital-analog hybrid system and its application to the automatic flight control system simulation research

    Science.gov (United States)

    1981-01-01

    The characteristics of a digital-analog hybrid system composed of a DJS-8 digital computer and a HMJ-200 analog computer are described as well as its applications to simulation research for an automatic flight control system. A hybrid computational example is included to illustrate the application.

  16. Architectural and operational considerations emerging from hybrid RF-optical network loading simulations

    Science.gov (United States)

    Chen, Yijiang; Abraham, Douglas S.; Heckman, David P.; Kwok, Andrew; MacNeal, Bruce E.; Tran, Kristy; Wu, Janet P.

    2016-03-01

    A technology demonstration of free space optical communication at interplanetary distances is planned via one or more future NASA deep-space missions. Such demonstrations will "pave the way" for operational use of optical communications on future robotic/potential Human missions. Hence, the Deep Space Network architecture will need to evolve. Preliminary attempts to model the anticipated future mission set and simulate how well it loads onto assumed architectures with combinations of RF and optical apertures have been evaluated. This paper discusses the results of preliminary loading simulations for hybrid RF-optical network architectures and highlights key mission and ground infrastructure considerations that emerge.

  17. Effects of Atomistic Domain Size on Hybrid Lattice Boltzmann-Molecular Dynamics Simulations of Dense Fluids

    Science.gov (United States)

    Dupuis, A.; Koumoutsakos, P.

    We present a convergence study for a hybrid Lattice Boltzmann-Molecular Dynamics model for the simulation of dense liquids. Time and length scales are decoupled by using an iterative Schwarz domain decomposition algorithm. The velocity field from the atomistic domain is introduced as forcing terms to the Lattice Boltzmann model of the continuum while the mean field of the continuum imposes mean field conditions for the atomistic domain. In the present paper we investigate the effect of varying the size of the atomistic subdomain in simulations of two dimensional flows of liquid argon past carbon nanotubes and assess the efficiency of the method.

  18. A hybrid Genetic and Simulated Annealing Algorithm for Chordal Ring implementation in large-scale networks

    DEFF Research Database (Denmark)

    Riaz, M. Tahir; Gutierrez Lopez, Jose Manuel; Pedersen, Jens Myrup

    2011-01-01

    The paper presents a hybrid Genetic and Simulated Annealing algorithm for implementing Chordal Ring structure in optical backbone network. In recent years, topologies based on regular graph structures gained a lot of interest due to their good communication properties for physical topology...... of the networks. There have been many use of evolutionary algorithms to solve the problems which are in combinatory complexity nature, and extremely hard to solve by exact approaches. Both Genetic and Simulated annealing algorithms are similar in using controlled stochastic method to search the solution....... The paper combines the algorithms in order to analyze the impact of implementation performance....

  19. Numerical Simulation of Carbon Nanotubes/GaAs Hybrid PV Devices with AMPS-1D

    Directory of Open Access Journals (Sweden)

    Georgi Xosrovashvili

    2014-01-01

    Full Text Available The performance and characteristics of a hybrid heterojunction single-walled carbon nanotube and GaAs solar cell are modelled and numerically simulated using AMPS-1D device simulation tool. The device physics and performance with different junction parameters are analysed. The results suggest that the open-circuit voltage changes very slightly by changing the electron affinity, acceptor and donor density while the other electrical parameters reach an optimum value. Increasing the concentration of a discrete defect density in the absorber layer decreases the electrical parameters. The current-voltage characteristics, quantum efficiency, band gap, and thickness variation of the photovoltaic response will be quantitatively considered.

  20. Simulation of storage performance on hydropneumatic driveline in dual hybrid hydraulic passenger car

    Directory of Open Access Journals (Sweden)

    Wasbari Faizil

    2017-01-01

    Full Text Available The charging process is one of the critical processes in the hydro-pneumatic driveline storage system. It converts the kinetic energy of the vehicle braking and coasting to the compression energy. This energy is stored in the storage device called the accumulator. The system is planned to be used on the dual hydro-pneumatic hybrid driveline and applied to a hydraulic hybrid passenger car. The aim of this paper is to find the effect of charging parameters on the storage performance through simulation. Through the storage behaviour, the desirable and optimal sizing of the accumulator can be selected. The paper emphasized on the effect of pressure elevation, pre-charge pressure, effective volume, thermal reaction and required time of the accumulator’s charging process. The circuit of charging process has been designed and simulated by using the hydraulic tool in the Automation Studio software. The simulation results were corroborated through the component specification for data rationality. Through the simulation, it was found that pre-charge pressure had a significant effect on the charging process. It determined the efficiency of the effective volume. The higher the pressure elevation, the higher the effective volume. Nevertheless, the more energy required to compress the nitrogen gas in the bladder. Besides, in term of volume displacement, higher volume displacement reduced charging time and lower the fluid temperature. The simulation had been positively highlighted the critical point in charging process which later on, benefited the sizing process in the component selection specification.

  1. High performance hybrid functional Petri net simulations of biological pathway models on CUDA.

    Science.gov (United States)

    Chalkidis, Georgios; Nagasaki, Masao; Miyano, Satoru

    2011-01-01

    Hybrid functional Petri nets are a wide-spread tool for representing and simulating biological models. Due to their potential of providing virtual drug testing environments, biological simulations have a growing impact on pharmaceutical research. Continuous research advancements in biology and medicine lead to exponentially increasing simulation times, thus raising the demand for performance accelerations by efficient and inexpensive parallel computation solutions. Recent developments in the field of general-purpose computation on graphics processing units (GPGPU) enabled the scientific community to port a variety of compute intensive algorithms onto the graphics processing unit (GPU). This work presents the first scheme for mapping biological hybrid functional Petri net models, which can handle both discrete and continuous entities, onto compute unified device architecture (CUDA) enabled GPUs. GPU accelerated simulations are observed to run up to 18 times faster than sequential implementations. Simulating the cell boundary formation by Delta-Notch signaling on a CUDA enabled GPU results in a speedup of approximately 7x for a model containing 1,600 cells.

  2. On the application of hybrid meshes in hydraulic machinery CFD simulations

    Science.gov (United States)

    Schlipf, M.; Tismer, A.; Riedelbauch, S.

    2016-11-01

    The application of two different hybrid mesh types for the simulation of a Francis runner for automated optimization processes without user input is investigated. Those mesh types are applied to simplified test cases such as flow around NACA airfoils to identify the special mesh resolution effects with reduced complexity, like rotating cascade flows, as they occur in a turbomachine runner channel. The analysis includes the application of those different meshes on the geometries by keeping defined quality criteria and exploring the influences on the simulation results. All results are compared with reference values gained by simulations with blockstructured hexahedron meshes and the same numerical scheme. This avoids additional inaccuracies caused by further numerical and experimental measurement methods. The results show that a simulation with hybrid meshes built up by a blockstructured domain with hexahedrons around the blade in combination with a tetrahedral far field in the channel is sufficient to get results which are almost as accurate as the results gained by the reference simulation. Furthermore this method is robust enough for automated processes without user input and enables comparable meshes in size, distribution and quality for different similar geometries as occurring in optimization processes.

  3. Simulation-based model checking approach to cell fate specification during Caenorhabditis elegans vulval development by hybrid functional Petri net with extension

    Directory of Open Access Journals (Sweden)

    Ueno Kazuko

    2009-04-01

    Full Text Available Abstract Background Model checking approaches were applied to biological pathway validations around 2003. Recently, Fisher et al. have proved the importance of model checking approach by inferring new regulation of signaling crosstalk in C. elegans and confirming the regulation with biological experiments. They took a discrete and state-based approach to explore all possible states of the system underlying vulval precursor cell (VPC fate specification for desired properties. However, since both discrete and continuous features appear to be an indispensable part of biological processes, it is more appropriate to use quantitative models to capture the dynamics of biological systems. Our key motivation of this paper is to establish a quantitative methodology to model and analyze in silico models incorporating the use of model checking approach. Results A novel method of modeling and simulating biological systems with the use of model checking approach is proposed based on hybrid functional Petri net with extension (HFPNe as the framework dealing with both discrete and continuous events. Firstly, we construct a quantitative VPC fate model with 1761 components by using HFPNe. Secondly, we employ two major biological fate determination rules – Rule I and Rule II – to VPC fate model. We then conduct 10,000 simulations for each of 48 sets of different genotypes, investigate variations of cell fate patterns under each genotype, and validate the two rules by comparing three simulation targets consisting of fate patterns obtained from in silico and in vivo experiments. In particular, an evaluation was successfully done by using our VPC fate model to investigate one target derived from biological experiments involving hybrid lineage observations. However, the understandings of hybrid lineages are hard to make on a discrete model because the hybrid lineage occurs when the system comes close to certain thresholds as discussed by Sternberg and Horvitz in

  4. Microstructure in two- and three-dimensional hybrid simulations of perpendicular collisionless shocks

    CERN Document Server

    Burgess, David; Gingell, Peter W; Trávníček, Pavel M

    2016-01-01

    Supercritical collisionless perpendicular shocks have an average macrostructure determined primarily by the dynamics of ions specularly reflected at the magnetic ramp. Within the overall macrostructure, instabilities, both linear and nonlinear, generate fluctuations and microstructure. To identify the sources of such microstructure, high-resolution two- and three-dimensional simulations have been carried out using the hybrid method, wherein the ions are treated as particles and the electron response is modelled as a massless fluid. We confirm the results of earlier 2-D simulations showing both field-parallel aligned propagating fluctuations and fluctuations carried by the reflected-gyrating ions. In addition, it is shown that, for 2-D simulations of the shock coplanarity plane, the presence of short-wavelength fluctuations in all magnetic components is associated with the ion Weibel instability driven at the upstream edge of the foot by the reflected-gyrating ions. In 3-D simulations we show for the first tim...

  5. An Investigation of a Hybrid Mixing Timescale Model for PDF Simulations of Turbulent Premixed Flames

    Science.gov (United States)

    Zhou, Hua; Kuron, Mike; Ren, Zhuyin; Lu, Tianfeng; Chen, Jacqueline H.

    2016-11-01

    Transported probability density function (TPDF) method features the generality for all combustion regimes, which is attractive for turbulent combustion simulations. However, the modeling of micromixing due to molecular diffusion is still considered to be a primary challenge for TPDF method, especially in turbulent premixed flames. Recently, a hybrid mixing rate model for TPDF simulations of turbulent premixed flames has been proposed, which recovers the correct mixing rates in the limits of flamelet regime and broken reaction zone regime while at the same time aims to properly account for the transition in between. In this work, this model is employed in TPDF simulations of turbulent premixed methane-air slot burner flames. The model performance is assessed by comparing the results from both direct numerical simulation (DNS) and conventional constant mechanical-to-scalar mixing rate model. This work is Granted by NSFC 51476087 and 91441202.

  6. Simulation-optimization framework for multi-site multi-season hybrid stochastic streamflow modeling

    Science.gov (United States)

    Srivastav, Roshan; Srinivasan, K.; Sudheer, K. P.

    2016-11-01

    A simulation-optimization (S-O) framework is developed for the hybrid stochastic modeling of multi-site multi-season streamflows. The multi-objective optimization model formulated is the driver and the multi-site, multi-season hybrid matched block bootstrap model (MHMABB) is the simulation engine within this framework. The multi-site multi-season simulation model is the extension of the existing single-site multi-season simulation model. A robust and efficient evolutionary search based technique, namely, non-dominated sorting based genetic algorithm (NSGA - II) is employed as the solution technique for the multi-objective optimization within the S-O framework. The objective functions employed are related to the preservation of the multi-site critical deficit run sum and the constraints introduced are concerned with the hybrid model parameter space, and the preservation of certain statistics (such as inter-annual dependence and/or skewness of aggregated annual flows). The efficacy of the proposed S-O framework is brought out through a case example from the Colorado River basin. The proposed multi-site multi-season model AMHMABB (whose parameters are obtained from the proposed S-O framework) preserves the temporal as well as the spatial statistics of the historical flows. Also, the other multi-site deficit run characteristics namely, the number of runs, the maximum run length, the mean run sum and the mean run length are well preserved by the AMHMABB model. Overall, the proposed AMHMABB model is able to show better streamflow modeling performance when compared with the simulation based SMHMABB model, plausibly due to the significant role played by: (i) the objective functions related to the preservation of multi-site critical deficit run sum; (ii) the huge hybrid model parameter space available for the evolutionary search and (iii) the constraint on the preservation of the inter-annual dependence. Split-sample validation results indicate that the AMHMABB model is

  7. A hybrid classical-quantum approach for ultra-scaled confined nanostructures : modeling and simulation*

    Directory of Open Access Journals (Sweden)

    Pietra Paola

    2012-04-01

    Full Text Available We propose a hybrid classical-quantum model to study the motion of electrons in ultra-scaled confined nanostructures. The transport of charged particles, considered as one dimensional, is described by a quantum effective mass model in the active zone coupled directly to a drift-diffusion problem in the rest of the device. We explain how this hybrid model takes into account the peculiarities due to the strong confinement and we present numerical simulations for a simplified carbon nanotube. Nous proposons un modèle hybride classique-quantique pour décrire le mouvement des électrons dans des nanostructures très fortement confinées. Le transport des particules, consideré unidimensionel, est décrit par un modèle quantique avec masse effective dans la zone active couplé à un problème de dérive-diffusion dans le reste du domaine. Nous expliquons comment ce modèle hybride prend en compte les spécificités de ce très fort confinement et nous présentons des résultats numériques pour un nanotube de carbone simplifié.

  8. Jovian Plasma Torus Interaction with Europa: 3D Hybrid Kinetic Simulation. First results

    Science.gov (United States)

    Lipatov, A. S.; Cooper, J. F.; Paterson, W. R.; Sittler, E. C.; Hartle, R. E.; Simpson, D. G.

    2010-01-01

    The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa-moon-magnetosphere system with respect to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo orbiter mission, and for planning flyby and orbital measurements, (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy etal.,2007;Shematovichetal.,2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyro radius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions).Non-thermal distributions of upstream plasma will be addressed in future work. Photoionization,electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider two models for background plasma:(a) with O(++) ions; (b) with O(++) and S(++) ions. The majority of O2 atmosphere is thermal with an extended cold population (Cassidyetal.,2007). A few first simulations already include an induced magnetic dipole; however, several important effects of induced magnetic fields arising from oceanic shell conductivity will be addressed in later work.

  9. Parameter estimation for chaotic systems using a hybrid adaptive cuckoo search with simulated annealing algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Zheng, E-mail: 19994035@sina.com [College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101 (China); Wang, Jun; Zhou, Bihua [National Defense Key Laboratory on Lightning Protection and Electromagnetic Camouflage, PLA University of Science and Technology, Nanjing 210007 (China); Zhou, Shudao [College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing 211101 (China); Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

    2014-03-15

    This paper introduces a novel hybrid optimization algorithm to establish the parameters of chaotic systems. In order to deal with the weaknesses of the traditional cuckoo search algorithm, the proposed adaptive cuckoo search with simulated annealing algorithm is presented, which incorporates the adaptive parameters adjusting operation and the simulated annealing operation in the cuckoo search algorithm. Normally, the parameters of the cuckoo search algorithm are kept constant that may result in decreasing the efficiency of the algorithm. For the purpose of balancing and enhancing the accuracy and convergence rate of the cuckoo search algorithm, the adaptive operation is presented to tune the parameters properly. Besides, the local search capability of cuckoo search algorithm is relatively weak that may decrease the quality of optimization. So the simulated annealing operation is merged into the cuckoo search algorithm to enhance the local search ability and improve the accuracy and reliability of the results. The functionality of the proposed hybrid algorithm is investigated through the Lorenz chaotic system under the noiseless and noise condition, respectively. The numerical results demonstrate that the method can estimate parameters efficiently and accurately in the noiseless and noise condition. Finally, the results are compared with the traditional cuckoo search algorithm, genetic algorithm, and particle swarm optimization algorithm. Simulation results demonstrate the effectiveness and superior performance of the proposed algorithm.

  10. Parameter estimation for chaotic systems using a hybrid adaptive cuckoo search with simulated annealing algorithm

    Science.gov (United States)

    Sheng, Zheng; Wang, Jun; Zhou, Shudao; Zhou, Bihua

    2014-03-01

    This paper introduces a novel hybrid optimization algorithm to establish the parameters of chaotic systems. In order to deal with the weaknesses of the traditional cuckoo search algorithm, the proposed adaptive cuckoo search with simulated annealing algorithm is presented, which incorporates the adaptive parameters adjusting operation and the simulated annealing operation in the cuckoo search algorithm. Normally, the parameters of the cuckoo search algorithm are kept constant that may result in decreasing the efficiency of the algorithm. For the purpose of balancing and enhancing the accuracy and convergence rate of the cuckoo search algorithm, the adaptive operation is presented to tune the parameters properly. Besides, the local search capability of cuckoo search algorithm is relatively weak that may decrease the quality of optimization. So the simulated annealing operation is merged into the cuckoo search algorithm to enhance the local search ability and improve the accuracy and reliability of the results. The functionality of the proposed hybrid algorithm is investigated through the Lorenz chaotic system under the noiseless and noise condition, respectively. The numerical results demonstrate that the method can estimate parameters efficiently and accurately in the noiseless and noise condition. Finally, the results are compared with the traditional cuckoo search algorithm, genetic algorithm, and particle swarm optimization algorithm. Simulation results demonstrate the effectiveness and superior performance of the proposed algorithm.

  11. A hybrid method for efficient and accurate simulations of diffusion compartment imaging signals

    Science.gov (United States)

    Rensonnet, Gaëtan; Jacobs, Damien; Macq, Benoît; Taquet, Maxime

    2015-12-01

    Diffusion-weighted imaging is sensitive to the movement of water molecules through the tissue microstructure and can therefore be used to gain insight into the tissue cellular architecture. While the diffusion signal arising from simple geometrical microstructure is known analytically, it remains unclear what diffusion signal arises from complex microstructural configurations. Such knowledge is important to design optimal acquisition sequences, to understand the limitations of diffusion-weighted imaging and to validate novel models of the brain microstructure. We present a novel framework for the efficient simulation of high-quality DW-MRI signals based on the hybrid combination of exact analytic expressions in simple geometric compartments such as cylinders and spheres and Monte Carlo simulations in more complex geometries. We validate our approach on synthetic arrangements of parallel cylinders representing the geometry of white matter fascicles, by comparing it to complete, all-out Monte Carlo simulations commonly used in the literature. For typical configurations, equal levels of accuracy are obtained with our hybrid method in less than one fifth of the computational time required for Monte Carlo simulations.

  12. Comparison of plasma data from ASPERA-3/Mars-Express with a 3-D hybrid simulation

    Directory of Open Access Journals (Sweden)

    A. Bößwetter

    2007-08-01

    Full Text Available The ELS and IMA sensors of the ASPERA-3 experiment onboard of Mars-Express (MEX can measure electron as well as ion moments. We compare these measurements for a specific orbit with the simulation results from a 3-D hybrid model. In the hybrid approximation the electrons are modeled as a massless charge-neutralizing fluid, whereas the ions are treated as individual particles. This approach allows gyroradius effects to be included in our model calculations of the Martian plasma environment because the gyroradii of the solar wind protons are in the range of several hundred kilometers and therefore comparable with the characteristic scales of the subsolar ionospheric interaction region. The position of both the bow shock and the Ion Composition Boundary (ICB manifest in the MEX data as well as in the results from the hybrid simulation nearly at the same location. The characteristic features of these boundaries, i.e. an increase of proton density and temperature at the Bow Shock and a transition from solar wind to ionospheric particles at the ICB, are clearly identifiable in the data.

  13. Performance of hybrid programming models for multiscale cardiac simulations: preparing for petascale computation.

    Science.gov (United States)

    Pope, Bernard J; Fitch, Blake G; Pitman, Michael C; Rice, John J; Reumann, Matthias

    2011-10-01

    Future multiscale and multiphysics models that support research into human disease, translational medical science, and treatment can utilize the power of high-performance computing (HPC) systems. We anticipate that computationally efficient multiscale models will require the use of sophisticated hybrid programming models, mixing distributed message-passing processes [e.g., the message-passing interface (MPI)] with multithreading (e.g., OpenMP, Pthreads). The objective of this study is to compare the performance of such hybrid programming models when applied to the simulation of a realistic physiological multiscale model of the heart. Our results show that the hybrid models perform favorably when compared to an implementation using only the MPI and, furthermore, that OpenMP in combination with the MPI provides a satisfactory compromise between performance and code complexity. Having the ability to use threads within MPI processes enables the sophisticated use of all processor cores for both computation and communication phases. Considering that HPC systems in 2012 will have two orders of magnitude more cores than what was used in this study, we believe that faster than real-time multiscale cardiac simulations can be achieved on these systems.

  14. Development and Simulation of a Type of Four-Shaft ECVT for a Hybrid Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Yong Zhang

    2016-02-01

    Full Text Available In hybrid electric vehicles with power-split configurations, the engine can be decoupled from the wheel and operated with improved fuel economy, while the entire efficiency of the powertrain is affected by the circular electric power flow. Two planetary gear (2-PG sets with adding brakes/clutches, namely a type of four shaft elelctric continuously variable transmission (ECVT can provide multi-mode operation for the powertrain and extend the efficient area. First, a conventional 2-PG AT (Automatic Transmission architecture is investigated. By analyzing and comparing the connection and operating modes based on the kinematic relationship and lever analogy, a feasible four-shaft ECVT architecture with two brakes and two simplified versions are picked. To make a trade-off between fuel economy and configuration complexity, an instantaneous optimal control strategy based on the equivalent consumption minimization strategy (ECMS concept is then developed and employed as the unified optimization method in the simulations of three different configurations. Finally, the simulation results show that the simplified versions are suboptimal sets and the fuel economy is sacrificed by the limits of different modes. From the viewpoint of concept design, a multi-mode power-split configuration is more suitable for hybrid electric vehicles. This research applied a systematic methodology from concept design to energy management optimization, which can provide the guidelines for researchers to select a suitable multi-mode power-split hybrid powertrain.

  15. Effects of aeration frequency on leachate quality and waste in simulated hybrid bioreactor landfills.

    Science.gov (United States)

    Ko, Jae Hac; Ma, Zeyu; Jin, Xiao; Xu, Qiyong

    2016-12-01

    Research has been conducted to investigate the effects of daily aeration frequency on leachate quality and waste settlement in simulated hybrid landfill bioreactors. Four laboratory-scale reactors were constructed and operated for about 10 months to simulate different bioreactor operations, including one anaerobic bioreactor and three hybrid bioreactors with different aeration frequencies (one, two, and four times per day). Chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) reduced more than 96% of the initial concentrations in all aerated bioreactors. The differences of COD and BOD5 reductions among tested aeration frequencies were relatively small. For ammonia nitrogen, the higher aeration frequency (two or four times per day) resulted in the quicker reduction. Overall, the concentrations of heavy metals (Cr, Co, Cu, Mn, Ni, and Zn) decreased over time except Cd and Pb. The reduction of redox-sensitive metal concentrations (Mn, Co, Ni, and Cu) was greater in aerated bioreactors than in anaerobic bioreactor. Settlement of municipal solid waste (MSW) was enhanced with higher frequency of aeration events (four times per day). In recent years, hybird bioreactor landfill technology has gained a lot of attention. Appropriate aeration rate is crucial for hybrid bioreactor operation, but few studies have been done and different results were obtained. Research was conducted to investigate the effects of daily aeration frequency on leachate quality and waste settlement. Results indicated that aeration can effectively accelerate waste stabilization and remove organic carbon concentration and total nitrogen in the leachate.

  16. Quasi-Static Single-Component Hybrid Simulation of a Composite Structure with Multi-Axis Control

    DEFF Research Database (Denmark)

    Høgh, J.; Waldbjørn, J.; Wittrup-Schmidt, J.

    2015-01-01

    This paper presents a quasi-static hybrid simulation performed on a single component structure. Hybrid simulation is a substructural technique, where a structure is divided into two sections: a numerical section of the main structure and a physical experiment of the remainder. In previous cases...... to evaluate the validity of the method, the results are compared to a test of the emulated structure – referred to here as the reference test. It was found that the error introduced by compliance in the load train was significant. Digital image correlation was for this reason implemented in the hybrid...

  17. A gas kinetic scheme for hybrid simulation of partially rarefied flows

    Science.gov (United States)

    Colonia, S.; Steijl, R.; Barakos, G.

    2017-06-01

    Approaches to predict flow fields that display rarefaction effects incur a cost in computational time and memory considerably higher than methods commonly employed for continuum flows. For this reason, to simulate flow fields where continuum and rarefied regimes coexist, hybrid techniques have been introduced. In the present work, analytically defined gas-kinetic schemes based on the Shakhov and Rykov models for monoatomic and diatomic gas flows, respectively, are proposed and evaluated with the aim to be used in the context of hybrid simulations. This should reduce the region where more expensive methods are needed by extending the validity of the continuum formulation. Moreover, since for high-speed rare¦ed gas flows it is necessary to take into account the nonequilibrium among the internal degrees of freedom, the extension of the approach to employ diatomic gas models including rotational relaxation process is a mandatory first step towards realistic simulations. Compared to previous works of Xu and coworkers, the presented scheme is de¦ned directly on the basis of kinetic models which involve a Prandtl number correction. Moreover, the methods are defined fully analytically instead of making use of Taylor expansion for the evaluation of the required derivatives. The scheme has been tested for various test cases and Mach numbers proving to produce reliable predictions in agreement with other approaches for near-continuum flows. Finally, the performance of the scheme, in terms of memory and computational time, compared to discrete velocity methods makes it a compelling alternative in place of more complex methods for hybrid simulations of weakly rarefied flows.

  18. A hybrid Tabu search-simulated annealing method to solve quadratic assignment problem

    Directory of Open Access Journals (Sweden)

    Mohamad Amin Kaviani

    2014-06-01

    Full Text Available Quadratic assignment problem (QAP has been considered as one of the most complicated problems. The problem is NP-Hard and the optimal solutions are not available for large-scale problems. This paper presents a hybrid method using tabu search and simulated annealing technique to solve QAP called TABUSA. Using some well-known problems from QAPLIB generated by Burkard et al. (1997 [Burkard, R. E., Karisch, S. E., & Rendl, F. (1997. QAPLIB–a quadratic assignment problem library. Journal of Global Optimization, 10(4, 391-403.], two methods of TABUSA and TS are both coded on MATLAB and they are compared in terms of relative percentage deviation (RPD for all instances. The performance of the proposed method is examined against Tabu search and the preliminary results indicate that the hybrid method is capable of solving real-world problems, efficiently.

  19. A general hybrid radiation transport scheme for star formation simulations on an adaptive grid

    CERN Document Server

    Klassen, Mikhail; Pudritz, Ralph E; Peters, Thomas; Banerjee, Robi; Buntemeyer, Lars

    2014-01-01

    Radiation feedback plays a crucial role in the process of star formation. In order to simulate the thermodynamic evolution of disks, filaments, and the molecular gas surrounding clusters of young stars, we require an efficient and accurate method for solving the radiation transfer problem. We describe the implementation of a hybrid radiation transport scheme in the adaptive grid-based FLASH general magnetohydrodynamics code. The hybrid scheme splits the radiative transport problem into a raytracing step and a diffusion step. The raytracer captures the first absorption event, as stars irradiate their environments, while the evolution of the diffuse component of the radiation field is handled by a flux-limited diffusion (FLD) solver. We demonstrate the accuracy of our method through a variety of benchmark tests including the irradiation of a static disk, subcritical and supercritical radiative shocks, and thermal energy equilibration. We also demonstrate the capability of our method for casting shadows and calc...

  20. Simulated Annealing Based Hybrid Forecast for Improving Daily Municipal Solid Waste Generation Prediction

    Directory of Open Access Journals (Sweden)

    Jingwei Song

    2014-01-01

    Full Text Available A simulated annealing (SA based variable weighted forecast model is proposed to combine and weigh local chaotic model, artificial neural network (ANN, and partial least square support vector machine (PLS-SVM to build a more accurate forecast model. The hybrid model was built and multistep ahead prediction ability was tested based on daily MSW generation data from Seattle, Washington, the United States. The hybrid forecast model was proved to produce more accurate and reliable results and to degrade less in longer predictions than three individual models. The average one-week step ahead prediction has been raised from 11.21% (chaotic model, 12.93% (ANN, and 12.94% (PLS-SVM to 9.38%. Five-week average has been raised from 13.02% (chaotic model, 15.69% (ANN, and 15.92% (PLS-SVM to 11.27%.

  1. N-S/DSMC hybrid simulation of hypersonic flow over blunt body including wakes

    Science.gov (United States)

    Li, Zhonghua; Li, Zhihui; Li, Haiyan; Yang, Yanguang; Jiang, Xinyu

    2014-12-01

    A hybrid N-S/DSMC method is presented and applied to solve the three-dimensional hypersonic transitional flows by employing the MPC (modular Particle-Continuum) technique based on the N-S and the DSMC method. A sub-relax technique is adopted to deal with information transfer between the N-S and the DSMC. The hypersonic flows over a 70-deg spherically blunted cone under different Kn numbers are simulated using the CFD, DSMC and hybrid N-S/DSMC method. The present computations are found in good agreement with DSMC and experimental results. The present method provides an efficient way to predict the hypersonic aerodynamics in near-continuum transitional flow regime.

  2. CAVE2: a hybrid reality environment for immersive simulation and information analysis

    Science.gov (United States)

    Febretti, Alessandro; Nishimoto, Arthur; Thigpen, Terrance; Talandis, Jonas; Long, Lance; Pirtle, J. D.; Peterka, Tom; Verlo, Alan; Brown, Maxine; Plepys, Dana; Sandin, Dan; Renambot, Luc; Johnson, Andrew; Leigh, Jason

    2013-03-01

    Hybrid Reality Environments represent a new kind of visualization spaces that blur the line between virtual environments and high resolution tiled display walls. This paper outlines the design and implementation of the CAVE2TM Hybrid Reality Environment. CAVE2 is the world's first near-seamless flat-panel-based, surround-screen immersive system. Unique to CAVE2 is that it will enable users to simultaneously view both 2D and 3D information, providing more flexibility for mixed media applications. CAVE2 is a cylindrical system of 24 feet in diameter and 8 feet tall, and consists of 72 near-seamless, off-axisoptimized passive stereo LCD panels, creating an approximately 320 degree panoramic environment for displaying information at 37 Megapixels (in stereoscopic 3D) or 74 Megapixels in 2D and at a horizontal visual acuity of 20/20. Custom LCD panels with shifted polarizers were built so the images in the top and bottom rows of LCDs are optimized for vertical off-center viewing- allowing viewers to come closer to the displays while minimizing ghosting. CAVE2 is designed to support multiple operating modes. In the Fully Immersive mode, the entire room can be dedicated to one virtual simulation. In 2D model, the room can operate like a traditional tiled display wall enabling users to work with large numbers of documents at the same time. In the Hybrid mode, a mixture of both 2D and 3D applications can be simultaneously supported. The ability to treat immersive work spaces in this Hybrid way has never been achieved before, and leverages the special abilities of CAVE2 to enable researchers to seamlessly interact with large collections of 2D and 3D data. To realize this hybrid ability, we merged the Scalable Adaptive Graphics Environment (SAGE) - a system for supporting 2D tiled displays, with Omegalib - a virtual reality middleware supporting OpenGL, OpenSceneGraph and Vtk applications.

  3. A comparison of simulated precipitation by hybrid isentropic-sigma and sigma models

    Science.gov (United States)

    Johnson, Donald R.; Zapotocny, Tom H.; Reames, Fred M.; Wolf, Bart J.; Pierce, R. B.

    1993-01-01

    Simulations of dry and moist baroclinic development from 10- and 22-layer hybrid isentropic-sigma coordinate models are compared with those from 11-, 27-, and 35-layer sigma coordinate models. The ability of the models to transport water vapor and simulate equivalent potential temperature is examined. Predictions of the timing, location, and amount of precipitation are compared. Several analytical distributions of water vapor are specified initially. It is shown that when the relative humidity is vertically uniform through a substantial extent of the atmosphere, all the models produce very similar precipitation distributions. However, when water vapor is confined to relatively shallow layers, the ability of the sigma coordinate models to simulate the timing, location, and amount of precipitation is severely compromised.

  4. Accelerated stochastic and hybrid methods for spatial simulations of reaction diffusion systems

    Science.gov (United States)

    Rossinelli, Diego; Bayati, Basil; Koumoutsakos, Petros

    2008-01-01

    Spatial distributions characterize the evolution of reaction-diffusion models of several physical, chemical, and biological systems. We present two novel algorithms for the efficient simulation of these models: Spatial τ-Leaping ( Sτ-Leaping), employing a unified acceleration of the stochastic simulation of reaction and diffusion, and Hybrid τ-Leaping ( Hτ-Leaping), combining a deterministic diffusion approximation with a τ-Leaping acceleration of the stochastic reactions. The algorithms are validated by solving Fisher's equation and used to explore the role of the number of particles in pattern formation. The results indicate that the present algorithms have a nearly constant time complexity with respect to the number of events (reaction and diffusion), unlike the exact stochastic simulation algorithm which scales linearly.

  5. On the Design, Characterization and Simulation of Hybrid Metal-Composite Interfaces

    Science.gov (United States)

    Kießling, R.; Ihlemann, J.; Pohl, M.; Stommel, M.; Dammann, C.; Mahnken, R.; Bobbert, M.; Meschut, G.; Hirsch, F.; Kästner, M.

    2017-02-01

    Multi-material lightweight designs are a key feature for the development of innovative and resource-efficient products. In the development of a hybrid composite, the interface between the joined components has to be considered in detail as it represents a typical location of the initialization of failure. This contribution gives an overview of the simulative engineering of metal-composite interfaces. To this end, several design aspects on the microscale and macroscale are explained and methods to model the mechanical behavior of the interface within finite element simulations. This comprises the utilization of cohesive elements with a continuum description of the interface. Likewise, traction-separation based cohesive elements, i.e. a zero-thickness idealization of the interface, are outlined and applied to a demonstration example. Within these finite element simulations, the constitutive behavior of the connected components has to be described by suitable material models. Therefore, inelastic material models at large strains are formulated based on rheological models.

  6. An Investigation of a Hybrid Mixing Model for PDF Simulations of Turbulent Premixed Flames

    Science.gov (United States)

    Zhou, Hua; Li, Shan; Wang, Hu; Ren, Zhuyin

    2015-11-01

    Predictive simulations of turbulent premixed flames over a wide range of Damköhler numbers in the framework of Probability Density Function (PDF) method still remain challenging due to the deficiency in current micro-mixing models. In this work, a hybrid micro-mixing model, valid in both the flamelet regime and broken reaction zone regime, is proposed. A priori testing of this model is first performed by examining the conditional scalar dissipation rate and conditional scalar diffusion in a 3-D direct numerical simulation dataset of a temporally evolving turbulent slot jet flame of lean premixed H2-air in the thin reaction zone regime. Then, this new model is applied to PDF simulations of the Piloted Premixed Jet Burner (PPJB) flames, which are a set of highly shear turbulent premixed flames and feature strong turbulence-chemistry interaction at high Reynolds and Karlovitz numbers. Supported by NSFC 51476087 and NSFC 91441202.

  7. On the use of reverse Brownian motion to accelerate hybrid simulations

    Science.gov (United States)

    Bakarji, Joseph; Tartakovsky, Daniel M.

    2017-04-01

    Multiscale and multiphysics simulations are two rapidly developing fields of scientific computing. Efficient coupling of continuum (deterministic or stochastic) constitutive solvers with their discrete (stochastic, particle-based) counterparts is a common challenge in both kinds of simulations. We focus on interfacial, tightly coupled simulations of diffusion that combine continuum and particle-based solvers. The latter employs the reverse Brownian motion (rBm), a Monte Carlo approach that allows one to enforce inhomogeneous Dirichlet, Neumann, or Robin boundary conditions and is trivially parallelizable. We discuss numerical approaches for improving the accuracy of rBm in the presence of inhomogeneous Neumann boundary conditions and alternative strategies for coupling the rBm solver with its continuum counterpart. Numerical experiments are used to investigate the convergence, stability, and computational efficiency of the proposed hybrid algorithm.

  8. On the Design, Characterization and Simulation of Hybrid Metal-Composite Interfaces

    Science.gov (United States)

    Kießling, R.; Ihlemann, J.; Pohl, M.; Stommel, M.; Dammann, C.; Mahnken, R.; Bobbert, M.; Meschut, G.; Hirsch, F.; Kästner, M.

    2016-09-01

    Multi-material lightweight designs are a key feature for the development of innovative and resource-efficient products. In the development of a hybrid composite, the interface between the joined components has to be considered in detail as it represents a typical location of the initialization of failure. This contribution gives an overview of the simulative engineering of metal-composite interfaces. To this end, several design aspects on the microscale and macroscale are explained and methods to model the mechanical behavior of the interface within finite element simulations. This comprises the utilization of cohesive elements with a continuum description of the interface. Likewise, traction-separation based cohesive elements, i.e. a zero-thickness idealization of the interface, are outlined and applied to a demonstration example. Within these finite element simulations, the constitutive behavior of the connected components has to be described by suitable material models. Therefore, inelastic material models at large strains are formulated based on rheological models.

  9. Simulation of the detective quantum efficiency for a hybrid pixel detector

    Energy Technology Data Exchange (ETDEWEB)

    Risco Norrlid, L. del [Department of Radiation Sciences, Uppsala University, Box 535, 751 21 Uppsala (Sweden)]. E-mail: lilian@tsl.uu.se; Edling, Fredrik [Department of Radiation Sciences, Uppsala University, Box 535, 751 21 Uppsala (Sweden); Fransson, K. [The Svedberg Laboratory, Uppsala University, Box 533, 751 21 Uppsala (Sweden); Brenner, R. [Department of Radiation Sciences, Uppsala University, Box 535, 751 21 Uppsala (Sweden); Bingefors, N. [Department of Radiation Sciences, Uppsala University, Box 535, 751 21 Uppsala (Sweden); Gustafsson, L. [Department of Radiation Sciences, Uppsala University, Box 535, 751 21 Uppsala (Sweden); Roennqvist, C. [Scanditronix Wellhoefer AB, Stalgatan 14, 754 50 Uppsala (Sweden)

    2005-05-11

    A simulation tool has been developed for the analysis of the performance of an X-ray imaging hybrid pixel detector. The photon transport and charge collection were simulated with the aid of the Monte Carlo based code GEANT and the readout signal processing was simulated in a program written in the LabView programming environment. Results of the spatial frequency-dependent detective quantum efficiency are presented and the influence of charge sharing, the threshold settings, level of exposure, the noise sources on the detector performance are studied. The detector was found to operate quantum limited down to an exposure of 0.08 {mu}Gy, below which it is limited by the readout noise. The threshold setting has a strong influence on both the efficiency and the spatial resolution due to charge sharing, and a compromise between the two is necessary. The optimized threshold value corresponds to half of the mean energy of the input spectrum.

  10. Exact hybrid particle/population simulation of rule-based models of biochemical systems.

    Directory of Open Access Journals (Sweden)

    Justin S Hogg

    2014-04-01

    Full Text Available Detailed modeling and simulation of biochemical systems is complicated by the problem of combinatorial complexity, an explosion in the number of species and reactions due to myriad protein-protein interactions and post-translational modifications. Rule-based modeling overcomes this problem by representing molecules as structured objects and encoding their interactions as pattern-based rules. This greatly simplifies the process of model specification, avoiding the tedious and error prone task of manually enumerating all species and reactions that can potentially exist in a system. From a simulation perspective, rule-based models can be expanded algorithmically into fully-enumerated reaction networks and simulated using a variety of network-based simulation methods, such as ordinary differential equations or Gillespie's algorithm, provided that the network is not exceedingly large. Alternatively, rule-based models can be simulated directly using particle-based kinetic Monte Carlo methods. This "network-free" approach produces exact stochastic trajectories with a computational cost that is independent of network size. However, memory and run time costs increase with the number of particles, limiting the size of system that can be feasibly simulated. Here, we present a hybrid particle/population simulation method that combines the best attributes of both the network-based and network-free approaches. The method takes as input a rule-based model and a user-specified subset of species to treat as population variables rather than as particles. The model is then transformed by a process of "partial network expansion" into a dynamically equivalent form that can be simulated using a population-adapted network-free simulator. The transformation method has been implemented within the open-source rule-based modeling platform BioNetGen, and resulting hybrid models can be simulated using the particle-based simulator NFsim. Performance tests show that

  11. Hybrid simulations: combining atomistic and coarse-grained force fields using virtual sites.

    Science.gov (United States)

    Rzepiela, Andrzej J; Louhivuori, Martti; Peter, Christine; Marrink, Siewert J

    2011-06-14

    Hybrid simulations, in which part of the system is represented at atomic resolution and the remaining part at a reduced, coarse-grained, level offer a powerful way to combine the accuracy associated with the atomistic force fields to the sampling speed obtained with coarse-grained (CG) potentials. In this work we introduce a straightforward scheme to perform hybrid simulations, making use of virtual sites to couple the two levels of resolution. With the help of these virtual sites interactions between molecules at different levels of resolution, i.e. between CG and atomistic molecules, are treated the same way as the pure CG-CG interactions. To test our method, we combine the Gromos atomistic force field with a number of coarse-grained potentials, obtained through several approaches that are designed to obtain CG potentials based on an existing atomistic model, namely iterative Boltzmann inversion, force matching, and a potential of mean force subtraction procedure (SB). We also explore the use of the MARTINI force field for the CG potential. A simple system, consisting of atomistic butane molecules dissolved in CG butane, is used to study the performance of our hybrid scheme. Based on the potentials of mean force for atomistic butane in CG solvent, and the properties of 1:1 mixtures of atomistic and CG butane which should exhibit ideal mixing behavior, we conclude that the MARTINI and SB potentials are particularly suited to be combined with the atomistic force field. The MARTINI potential is subsequently used to perform hybrid simulations of atomistic dialanine peptides in both CG butane and water. Compared to a fully atomistic description of the system, the hybrid description gives similar results provided that the dielectric screening of water is accounted for. Within the field of biomolecules, our method appears ideally suited to study e.g. protein-ligand binding, where the active site and ligand are modeled in atomistic detail and the rest of the protein

  12. A Robust Method for Handling Low Density Regions in Hybrid Simulations for Collisionless Plasmas

    CERN Document Server

    Amano, Takanobu; Shirakawa, Keisuke

    2014-01-01

    A robust method to handle vacuum and near vacuum regions in hybrid simulations for space and astrophysical plasmas is presented. The conventional hybrid simulation model dealing with kinetic ions and a massless charge-neutralizing electron fluid is known to be susceptible to numerical instability due to divergence of the whistler-mode wave dispersion, as well as division-by-density operation in regions of low density. Consequently, a pure vacuum region is not allowed to exist in the simulation domain unless some ad hoc technique is used. To resolve this difficulty, an alternative way to introduce finite electron inertia effect is proposed. Contrary to the conventional method, the proposed one introduces a correction to the electric field rather than the magnetic field. It is shown that the generalized Ohm's law correctly reduces to Laplace's equation in a vacuum which therefore does not involve any numerical problems. In addition, a variable ion-to-electron mass ratio is introduced to reduce the phase velocit...

  13. Time-domain hybrid method for simulating large amplitude motions of ships advancing in waves

    Directory of Open Access Journals (Sweden)

    Shukui Liu

    2011-03-01

    Full Text Available Typical results obtained by a newly developed, nonlinear time domain hybrid method for simulating large amplitude motions of ships advancing with constant forward speed in waves are presented. The method is hybrid in the way of combining a time-domain transient Green function method and a Rankine source method. The present approach employs a simple double integration algorithm with respect to time to simulate the free-surface boundary condition. During the simulation, the diffraction and radiation forces are computed by pressure integration over the mean wetted surface, whereas the incident wave and hydrostatic restoring forces/moments are calculated on the instantaneously wetted surface of the hull. Typical numerical results of application of the method to the seakeeping performance of a standard containership, namely the ITTC S175, are herein presented. Comparisons have been made between the results from the present method, the frequency domain 3D panel method (NEWDRIFT of NTUA-SDL and available experimental data and good agreement has been observed for all studied cases between the results of the present method and comparable other data.

  14. Stochastic analysis and simulation of hydrometeorological processes for optimizing hybrid renewable energy systems

    Science.gov (United States)

    Tsekouras, Georgios; Ioannou, Christos; Efstratiadis, Andreas; Koutsoyiannis, Demetris

    2013-04-01

    The drawbacks of conventional energy sources including their negative environmental impacts emphasize the need to integrate renewable energy sources into energy balance. However, the renewable sources strongly depend on time varying and uncertain hydrometeorological processes, including wind speed, sunshine duration and solar radiation. To study the design and management of hybrid energy systems we investigate the stochastic properties of these natural processes, including possible long-term persistence. We use wind speed and sunshine duration time series retrieved from a European database of daily records and we estimate representative values of the Hurst coefficient for both variables. We conduct simultaneous generation of synthetic time series of wind speed and sunshine duration, on yearly, monthly and daily scale. To this we use the Castalia software system which performs multivariate stochastic simulation. Using these time series as input, we perform stochastic simulation of an autonomous hypothetical hybrid renewable energy system and optimize its performance using genetic algorithms. For the system design we optimize the sizing of the system in order to satisfy the energy demand with high reliability also minimizing the cost. While the simulation scale is the daily, a simple method allows utilizing the subdaily distribution of the produced wind power. Various scenarios are assumed in order to examine the influence of input parameters, such as the Hurst coefficient, and design parameters such as the photovoltaic panel angle.

  15. Real time hybrid simulation with online model updating: An analysis of accuracy

    Science.gov (United States)

    Ou, Ge; Dyke, Shirley J.; Prakash, Arun

    2017-02-01

    In conventional hybrid simulation (HS) and real time hybrid simulation (RTHS) applications, the information exchanged between the experimental substructure and numerical substructure is typically restricted to the interface boundary conditions (force, displacement, acceleration, etc.). With additional demands being placed on RTHS and recent advances in recursive system identification techniques, an opportunity arises to improve the fidelity by extracting information from the experimental substructure. Online model updating algorithms enable the numerical model of components (herein named the target model), that are similar to the physical specimen to be modified accordingly. This manuscript demonstrates the power of integrating a model updating algorithm into RTHS (RTHSMU) and explores the possible challenges of this approach through a practical simulation. Two Bouc-Wen models with varying levels of complexity are used as target models to validate the concept and evaluate the performance of this approach. The constrained unscented Kalman filter (CUKF) is selected for using in the model updating algorithm. The accuracy of RTHSMU is evaluated through an estimation output error indicator, a model updating output error indicator, and a system identification error indicator. The results illustrate that, under applicable constraints, by integrating model updating into RTHS, the global response accuracy can be improved when the target model is unknown. A discussion on model updating parameter sensitivity to updating accuracy is also presented to provide guidance for potential users.

  16. Thermalization of Na+ Pickup Ions in Mercury's Magnetosheath and Magnetosphere via Hybrid Simulation

    Science.gov (United States)

    Boardsen, S. A.; Omidi, N.; Slavin, J. A.

    2007-12-01

    In previous studies it has been suggested that the incorporation of Na+ pickup ions into Mercury's magnetosphere could have a significant impact on various magnetospheric processes. Test particle simulations indicate that freshly created Na+ ions are rapidly energized and lost from the system. In order to incorporate these ions into the bulk magnetospheric plasma they must be thermalized. A recent study that used linear theory suggests that the wavelengths of electromagnetic ion cyclotron waves may be to large and may not grow to sufficient amplitudes to thermalize these ions and concluded that global thermalization of these ions is not possible. However, under certain solar wind and IMF conditions such thermalization might take place in limited regions of Mercury's magnetosphere, primarily in the sub-solar magnetosheath. Due the small scale size of Mercury's magnetosphere compared to the gyro-radii of these heavy ions and their associated wave modes, hybrid simulation with a kinetic treatment for the ions and a fluid treatment for the electrons may be the only way to study if thermalization of Na+ can occur. Preliminary results of a hybrid simulation that incorporates the Na+ pickup ions in its kinetic treatment will be presented.

  17. Modelization and Simulation of an Electric and Fuel Cell Hybrid Vehicle under Real Conditions

    Directory of Open Access Journals (Sweden)

    Victor Alfonsin

    2015-06-01

    Full Text Available This paper presents a toolbox for the simulation of a zero emission urban hybrid bus, which combines batteries and fuel cells. This type of vehicle performs predefined routes with a certain frequency, then they are an ideal option to the replacement of combustion engines with renewable energy systems. The simulation of these vehicles can be made for different standard driving cycles (ECE-15, EUDC, NEDC, SFUDS or for real routes from GPS device data. This will allow to consider the orography of the route, considering the slope that overcomes the vehicle at each time, generally this parameter is not included in other models, and it could become a determining factor for the applicability of these vehicles on certain specified routes. Moreover, this tool lets to study and to analyse other not easily quantifiable factors, such as the weather or peak-hour traffic. Finally, the performance of an urban hybrid bus was investigated to assess its theoretical range and the technical feasibility of zero-emission vehicles. Keywords: Electric vehicle; Battery; Fuel cell; Hydrogen; Simulation 

  18. 2D-3D hybrid stabilized finite element method for tsunami runup simulations

    Science.gov (United States)

    Takase, S.; Moriguchi, S.; Terada, K.; Kato, J.; Kyoya, T.; Kashiyama, K.; Kotani, T.

    2016-09-01

    This paper presents a two-dimensional (2D)-three-dimensional (3D) hybrid stabilized finite element method that enables us to predict a propagation process of tsunami generated in a hypocentral region, which ranges from offshore propagation to runup to urban areas, with high accuracy and relatively low computational costs. To be more specific, the 2D shallow water equation is employed to simulate the propagation of offshore waves, while the 3D Navier-Stokes equation is employed for the runup in urban areas. The stabilized finite element method is utilized for numerical simulations for both of the 2D and 3D domains that are independently discretized with unstructured meshes. The multi-point constraint and transmission methods are applied to satisfy the continuity of flow velocities and pressures at the interface between the resulting 2D and 3D meshes, since neither their spatial dimensions nor node arrangements are consistent. Numerical examples are presented to demonstrate the performance of the proposed hybrid method to simulate tsunami behavior, including offshore propagation and runup to urban areas, with substantially lower computation costs in comparison with full 3D computations.

  19. Simulating Study on Drive System Performance for Hybrid Electric Bus Based on ADVISOR

    Directory of Open Access Journals (Sweden)

    Wang Xingxing

    2017-01-01

    Full Text Available Hybrid electric bus has a number of advantages when compared with ordinary passenger cars, but in the dynamic matching and the vehicle performance are difficult to detect, thus limits its development process. In this paper, combined with the actual models, the hybrid electric bus module parameters were modified in the software of ADVISOR (Advanced Vehicle Simulator, main including: module of the vehicle, the wheel module, motor module, a battery module and engine module, three kinds of bus models for A, B and C were established, and the related performance that need to be analyzed was set up, such as acceleration, gradability, emissions and energy utilization and so on, in order to ensure the vehicle running in the same environment and convenient for comparison, a fixed vehicle driving cycles was chose, then the simulation results was analyzed, and the various performance was compared with the dynamic indicators and economic indicators which determined by referencing of traditional city bus standard and each other, and finally, the performance optimal model of B was chose out which can meet the demand, its related performance parameters of the simulation results are as follows: the best gradability is 26%, maximum speed is 72.7km/h, maximum acceleration is 1.7m/s2, 0~50km/h acceleration time is 9.5s and fuel consumption is 25L/km.

  20. Combining cell-based hydrodynamics with hybrid particle-field simulations: efficient and realistic simulation of structuring dynamics.

    Science.gov (United States)

    Sevink, G J A; Schmid, F; Kawakatsu, T; Milano, G

    2017-02-22

    We have extended an existing hybrid MD-SCF simulation technique that employs a coarsening step to enhance the computational efficiency of evaluating non-bonded particle interactions. This technique is conceptually equivalent to the single chain in mean-field (SCMF) method in polymer physics, in the sense that non-bonded interactions are derived from the non-ideal chemical potential in self-consistent field (SCF) theory, after a particle-to-field projection. In contrast to SCMF, however, MD-SCF evolves particle coordinates by the usual Newton's equation of motion. Since collisions are seriously affected by the softening of non-bonded interactions that originates from their evaluation at the coarser continuum level, we have devised a way to reinsert the effect of collisions on the structural evolution. Merging MD-SCF with multi-particle collision dynamics (MPCD), we mimic particle collisions at the level of computational cells and at the same time properly account for the momentum transfer that is important for a realistic system evolution. The resulting hybrid MD-SCF/MPCD method was validated for a particular coarse-grained model of phospholipids in aqueous solution, against reference full-particle simulations and the original MD-SCF model. We additionally implemented and tested an alternative and more isotropic finite difference gradient. Our results show that efficiency is improved by merging MD-SCF with MPCD, as properly accounting for hydrodynamic interactions considerably speeds up the phase separation dynamics, with negligible additional computational costs compared to efficient MD-SCF. This new method enables realistic simulations of large-scale systems that are needed to investigate the applications of self-assembled structures of lipids in nanotechnologies.

  1. Simulation and experimental results of hybrid electric machine with a novel flux control strategy

    Directory of Open Access Journals (Sweden)

    Paplicki Piotr

    2015-03-01

    Full Text Available The paper presents selected simulation and experimental results of a hybrid ECPMS-machine (Electric Controlled Permanent Magnet Synchronous Machine. This permanent magnets (PMs excited machine offers an extended magnetic field control capability which makes it suitable for battery electric vehicle (BEV drives. Rotor, stator and the additional direct current control coil of the machine are analyzed in detail. The control system and strategy, the diagram of power supply system and an equivalent circuit model of the ECPMS-machine are presented. Influence of the additional excitation on the performance parameters of the machine, such as: torque, efficiency, speed limits and back-EMF have also been discussed.

  2. Plasma environment of magnetized asteroids: a 3-D hybrid simulation study

    Directory of Open Access Journals (Sweden)

    S. Simon

    2006-03-01

    Full Text Available The interaction of a magnetized asteroid with the solar wind is studied by using a three-dimensional hybrid simulation code (fluid electrons, kinetic ions. When the obstacle's intrinsic magnetic moment is sufficiently strong, the interaction region develops signs of magnetospheric structures. On the one hand, an area from which the solar wind is excluded forms downstream of the obstacle. On the other hand, the interaction region is surrounded by a boundary layer which indicates the presence of a bow shock. By analyzing the trajectories of individual ions, it is demonstrated that kinetic effects have global consequences for the structure of the interaction region.

  3. New hybrid voxelized/analytical primitive in Monte Carlo simulations for medical applications

    Science.gov (United States)

    Bert, Julien; Lemaréchal, Yannick; Visvikis, Dimitris

    2016-05-01

    Monte Carlo simulations (MCS) applied in particle physics play a key role in medical imaging and particle therapy. In such simulations, particles are transported through voxelized phantoms derived from predominantly patient CT images. However, such voxelized object representation limits the incorporation of fine elements, such as artificial implants from CAD modeling or anatomical and functional details extracted from other imaging modalities. In this work we propose a new hYbrid Voxelized/ANalytical primitive (YVAN) that combines both voxelized and analytical object descriptions within the same MCS, without the need to simultaneously run two parallel simulations, which is the current gold standard methodology. Given that YVAN is simply a new primitive object, it does not require any modifications on the underlying MC navigation code. The new proposed primitive was assessed through a first simple MCS. Results from the YVAN primitive were compared against an MCS using a pure analytical geometry and the layer mass geometry concept. A perfect agreement was found between these simulations, leading to the conclusion that the new hybrid primitive is able to accurately and efficiently handle phantoms defined by a mixture of voxelized and analytical objects. In addition, two application-based evaluation studies in coronary angiography and intra-operative radiotherapy showed that the use of YVAN was 6.5% and 12.2% faster than the layered mass geometry method, respectively, without any associated loss of accuracy. However, the simplification advantages and differences in computational time improvements obtained with YVAN depend on the relative proportion of the analytical and voxelized structures used in the simulation as well as the size and number of triangles used in the description of the analytical object meshes.

  4. New hybrid voxelized/analytical primitive in Monte Carlo simulations for medical applications.

    Science.gov (United States)

    Bert, Julien; Lemaréchal, Yannick; Visvikis, Dimitris

    2016-05-01

    Monte Carlo simulations (MCS) applied in particle physics play a key role in medical imaging and particle therapy. In such simulations, particles are transported through voxelized phantoms derived from predominantly patient CT images. However, such voxelized object representation limits the incorporation of fine elements, such as artificial implants from CAD modeling or anatomical and functional details extracted from other imaging modalities. In this work we propose a new hYbrid Voxelized/ANalytical primitive (YVAN) that combines both voxelized and analytical object descriptions within the same MCS, without the need to simultaneously run two parallel simulations, which is the current gold standard methodology. Given that YVAN is simply a new primitive object, it does not require any modifications on the underlying MC navigation code. The new proposed primitive was assessed through a first simple MCS. Results from the YVAN primitive were compared against an MCS using a pure analytical geometry and the layer mass geometry concept. A perfect agreement was found between these simulations, leading to the conclusion that the new hybrid primitive is able to accurately and efficiently handle phantoms defined by a mixture of voxelized and analytical objects. In addition, two application-based evaluation studies in coronary angiography and intra-operative radiotherapy showed that the use of YVAN was 6.5% and 12.2% faster than the layered mass geometry method, respectively, without any associated loss of accuracy. However, the simplification advantages and differences in computational time improvements obtained with YVAN depend on the relative proportion of the analytical and voxelized structures used in the simulation as well as the size and number of triangles used in the description of the analytical object meshes.

  5. Self-consistent hybrid neoclassical-magnetohydrodynamic simulations of axisymmetric plasmas

    Science.gov (United States)

    Lyons, Brendan Carrick

    Neoclassical effects (e.g., conductivity reduction and bootstrap currents) have a profound impact on many magnetohydrodynamic (MHD) instabilities in toroidally-confined plasmas, including tearing modes, edge-localized modes, and resistive wall modes. High-fidelity simulations of such phenomena require a multiphysics code that self-consistently couples the kinetic and fluid models. We review a hybrid formulation from the recent literatureAB that is appropriate for such studies. In particular, the formulation uses a set of time-dependent drift-kinetic equations (DKEs) to advance the non-Maxwellian part of the electron and ion distribution functions (fNM) with linearized Fokker-Planck-Landau collision operators. The form of the DKEs used were derived in a Chapman-Enskog-like fashion, ensuring that fNM carries no density, momentum, or temperature. Rather, these quantities are contained within the background Maxwellian and are evolved by a set of MHD equations which are closed by moments of fNM . We then present two DKE solvers based upon this formulation in axisymmetric toroidal geometries. The Neoclassical Ion-Electron Solver (NIES) solves the steady-state DKEs in the low-collisionality limit. Convergence and benchmark studies are discussed, providing a proof-of-principle that this new formulation can accurately reproduce results from the literature in the limit considered. We then present the DK4D code which evolves the finite-collisionality DKEs time-dependently. Computational methods used and successful benchmarks to other neoclassical models and codes are discussed. Furthermore, we couple DK4D to a reduced, transport-timescale MHD code. The resulting hybrid code is used to simulate the evolution of the current density in a large-aspect-ratio plasma in the presence of several different time-dependent pressure profiles. These simulations demonstrate the self-consistent, dynamic formation of the ohmic and bootstrap currents. In the slowly-evolving plasmas considered

  6. Appropriate choice of collision-induced dissociation energy for qualitative analysis of notoginsenosides based on liquid chromatography hybrid ion trap time-of-flight mass spectrometry.

    Science.gov (United States)

    Wang, Guang-Ji; Fu, Han-Xu; Xiao, Jing-Cheng; Ye, Wei; Rao, Tai; Shao, Yu-Hao; Kang, Dian; Xie, Lin; Liang, Yan

    2016-04-01

    Liquid chromatography hybrid ion trap/time-of-flight mass spectrometry possessesd both the MS(n) ability of ion trap and the excellent resolution of a time-of-flight, and has been widely used to identify drug metabolites and determine trace multi-components for in natural products. Collision energy, one of the most important factors in acquiring MS(n) information, could be set freely in the range of 10%-400%. Herein, notoginsenosides were chosen as model compounds to build a novel methodology for the collision energy optimization. Firstly, the fragmental patterns of the representatives for the authentic standards of protopanaxadiol-type and protopanaxatriol-type notoginsenosides authentic standards were obtained based on accurate MS(2) and MS(3) measurements via liquid chromatography hybrid ion trap/time-of-flight mass spectrometry. Then the extracted ion chromatograms of characteristic product ions of notoginsenosides in Panax Notoginseng Extract, which were produced under a series of collision energies and, were compared to screen out the optimum collision energies values for MS(2) and MS(3). The results demonstrated that the qualitative capability of liquid chromatography hybrid ion trap/time-of-flight mass spectrometry was greatly influenced by collision energies, and 50% of MS(2) collision energy was found to produce the highest collision-induced dissociation efficiency for notoginsenosides. BesidesAddtionally, the highest collision-induced dissociation efficiency appeared when the collision energy was set at 75% in the MS(3) stage.

  7. Increasing the sampling efficiency of protein conformational transition using velocity-scaling optimized hybrid explicit/implicit solvent REMD simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yuqi; Wang, Jinan; Shao, Qiang, E-mail: qshao@mail.shcnc.ac.cn, E-mail: Jiye.Shi@ucb.com, E-mail: wlzhu@mail.shcnc.ac.cn; Zhu, Weiliang, E-mail: qshao@mail.shcnc.ac.cn, E-mail: Jiye.Shi@ucb.com, E-mail: wlzhu@mail.shcnc.ac.cn [ACS Key Laboratory of Receptor Research, Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203 (China); Shi, Jiye, E-mail: qshao@mail.shcnc.ac.cn, E-mail: Jiye.Shi@ucb.com, E-mail: wlzhu@mail.shcnc.ac.cn [UCB Pharma, 216 Bath Road, Slough SL1 4EN (United Kingdom)

    2015-03-28

    The application of temperature replica exchange molecular dynamics (REMD) simulation on protein motion is limited by its huge requirement of computational resource, particularly when explicit solvent model is implemented. In the previous study, we developed a velocity-scaling optimized hybrid explicit/implicit solvent REMD method with the hope to reduce the temperature (replica) number on the premise of maintaining high sampling efficiency. In this study, we utilized this method to characterize and energetically identify the conformational transition pathway of a protein model, the N-terminal domain of calmodulin. In comparison to the standard explicit solvent REMD simulation, the hybrid REMD is much less computationally expensive but, meanwhile, gives accurate evaluation of the structural and thermodynamic properties of the conformational transition which are in well agreement with the standard REMD simulation. Therefore, the hybrid REMD could highly increase the computational efficiency and thus expand the application of REMD simulation to larger-size protein systems.

  8. Optimization of Hybrid Power Trains by Mechanistic System Simulations Optimisation de groupes motopropulseurs électriques hybrides par simulation du système mécanique

    Directory of Open Access Journals (Sweden)

    Katrašnik T.

    2013-05-01

    Full Text Available The paper presents a mechanistic system level simulation model for mode/big hybrid and conventional vehicle topologies. The paper addresses the Dynamic interaction between different domains: internal combustion engine. exhaust after treatment devices, electric components. mechanical drive train. cooling circuit system and corresponding control units. To achieve a good ratio between accuracy. predictability and computational speed of the model an innovative time domain decoupling is presented, which is based on applying domain specific integration steps to ditferent domains and subsequent consistent cross-domain coupling ol’thefluxes. In addition, a computationally efficient frunieveork for transporting active and passive gaseous species is introduced to combine computational efficiency with the need for modeling pollutant transport in the gas path. The applicability and versatility of the mechanistic system level simulations model is presented through analyses of transient phenomena caused by the high interdependency of the sub-systems, i.e. domains. Results of a hyt’hrid vehicle are compared to results of a conventional vehicle to highlight differences in operating regimes of partiular components that are inherent to particular poster train topology. L’article présente un modèle de simulation au niveau mécanique destiné à la modélisation de topologies de véhicules hydrides et conventionnels. L’article décrit l’interaction dynamique entre différents domaines : moteur à combustion interne, dispositifs de post-traitement d’échappement, composants électriques, chaîne cinématique mécanique, circuit de refroidissement et les unités de contrôle correspondantes. Afin d’obtenir un rapport correct entre précision, prévisibilité et vitesse de calculs du modèle, un découplage innovant du domaine temporel est présenté, lequel est basé sur l’application à différents domaines, d’étapes d’intégration sp

  9. A hybrid model for the computationally-efficient simulation of the cerebellar granular layer

    Directory of Open Access Journals (Sweden)

    Anna eCattani

    2016-04-01

    Full Text Available The aim of the present paper is to efficiently describe the membrane potential dynamics of neural populations formed by species having a high density difference in specific brain areas. We propose a hybrid model whose main ingredients are a conductance-based model (ODE system and its continuous counterpart (PDE system obtained through a limit process in which the number of neurons confined in a bounded region of the brain tissue is sent to infinity. Specifically, in the discrete model, each cell is described by a set of time-dependent variables, whereas in the continuum model, cells are grouped into populations that are described by a set of continuous variables.Communications between populations, which translate into interactions among the discrete and the continuous models, are the essence of the hybrid model we present here. The cerebellum and cerebellum-like structures show in their granular layer a large difference in the relative density of neuronal species making them a natural testing ground for our hybrid model. By reconstructing the ensemble activity of the cerebellar granular layer network and by comparing our results to a more realistic computational network, we demonstrate that our description of the network activity, even though it is not biophysically detailed, is still capable of reproducing salient features of neural network dynamics. Our modeling approach yields a significant computational cost reduction by increasing the simulation speed at least $270$ times. The hybrid model reproduces interesting dynamics such as local microcircuit synchronization, traveling waves, center-surround and time-windowing.

  10. Modeling And Simulation As The Basis For Hybridity In The Graphic Discipline Learning/Teaching Area

    Directory of Open Access Journals (Sweden)

    Jana Žiljak Vujić

    2009-01-01

    Full Text Available Only some fifteen years have passed since the scientific graphics discipline was established. In the transition period from the College of Graphics to «Integrated Graphic Technology Studies» to the contemporary Faculty of Graphics Arts with the University in Zagreb, three main periods of development can be noted: digital printing, computer prepress and automatic procedures in postpress packaging production. Computer technology has enabled a change in the methodology of teaching graphics technology and studying it on the level of secondary and higher education. The task has been set to create tools for simulating printing processes in order to master the program through a hybrid system consisting of methods that are separate in relation to one another: learning with the help of digital models and checking in the actual real system. We are setting a hybrid project for teaching because the overall acquired knowledge is the result of completely different methods. The first method is on the free programs level functioning without consequences. Everything remains as a record in the knowledge database that can be analyzed, statistically processed and repeated with new parameter values of the system being researched. The second method uses the actual real system where the results are in proving the value of new knowledge and this is something that encourages and stimulates new cycles of hybrid behavior in mastering programs. This is the area where individual learning incurs. The hybrid method allows the possibility of studying actual situations on a computer model, proving it on an actual real model and entering the area of learning envisaging future development.

  11. Modeling and Simulation as the Basis for Hybridity in the Graphic Discipline Learning/Teaching Area

    Directory of Open Access Journals (Sweden)

    Vilko Ziljak

    2009-11-01

    Full Text Available Only some fifteen years have passed since the scientific graphics discipline was established. In the transition period from the College of Graphics to «Integrated Graphic Technology Studies» to the contemporary Faculty of Graphics Arts with the University in Zagreb, three main periods of development can be noted: digital printing, computer prepress and automatic procedures in postpress packaging production. Computer technology has enabled a change in the methodology of teaching graphics technology and studying it on the level of secondary and higher education. The task has been set to create tools for simulating printing processes in order to master the program through a hybrid system consisting of methods that are separate in relation to one another: learning with the help of digital models and checking in the actual real system.  We are setting a hybrid project for teaching because the overall acquired knowledge is the result of completely different methods. The first method is on the free programs level functioning without consequences. Everything remains as a record in the knowledge database that can be analyzed, statistically processed and repeated with new parameter values of the system being researched. The second method uses the actual real system where the results are in proving the value of new knowledge and this is something that encourages and stimulates new cycles of hybrid behavior in mastering programs. This is the area where individual learning incurs. The hybrid method allows the possibility of studying actual situations on a computer model, proving it on an actual real model and entering the area of learning envisaging future development.

  12. Towards Reconfigurable, Separable and Hard Real-Time Hybrid Simulation and Test Systems

    Science.gov (United States)

    Quartier, F.; Delatte, B.; Joubert, M.

    2009-05-01

    Formation flight needs several new technologies, new disciplines, new approaches and above all, more concurrent engineering by more players. One of the problems to be addressed are more complex simulation and test systems that are easy to re-configure to include parts of the target hardware and that can provide sufficient power to handle simulation cores that are requiring one to two orders of magnitude more processing power than the current technology provides. Critical technologies that are already addressed by CNES and Spacebel are study model reuse and simulator reconfigurability (Basiles), model portability (SMP2) and the federation of several simulators using HLA. Two more critical issues are addressed in ongoing R&D work by CNES and Spacebel and are covered by this paper and concern the time engineering and management. The first issue concerns separability (characterisation, identification and handling of separable subsystems) and the consequences on practical systems. Experiments on the Pleiades operational simulator have shown that adding precise simulation of instruments such as Doris and the Star Tracker can be added without significantly impacting overall performance. Improved time analysis leads to better system understanding and testability. The second issue concerns architectures for distributed hybrid simulators systems that provide hard real-time capabilities and can react with a relative time precision and jitter that is in the 10 to 50 µsecond range using mainstream PC's and mainstream Operating Systems. This opens a way to make smaller economic hardware test systems that can be reconfigured to make large hardware test systems without restarting development. Although such systems were considered next to impossible till now, distributed hard real-time systems are getting in reach when modern but mainstream electronics are used and when processor cores can be isolated and reserved for real-time cores. This requires a complete rethinking of the

  13. Gallbladder Removal Simulation for Laparoscopic Surgery Training:A Hybrid Modeling Method

    Institute of Scientific and Technical Information of China (English)

    Youngjun Kim; Dongjune Chang; Jungsik Kim; Sehyung Park

    2013-01-01

    Laparoscopic surgery has many advantages,but it is difficult for a surgeon to achieve the necessary surgical skills.Recently,virtual training simulations have been gaining interest because they can provide a safe and efficient learning environment for medical students and novice surgeons.In this paper,we present a hybrid modeling method for simulating gallbladder removal that uses both the boundary element method (BEM) and the finite element method (FEM).Each modeling method is applied according to the deformable properties of human organs:BEM for the liver and FEM for the gallbladder.Connective tissues between the liver and the gallbladder are also included in the surgical simulation.Deformations in the liver and the gallbladder models are transferred via connective tissue springs using a mass-spring method.Special effects and techniques are developed to achieve realistic simulations,and the software is integrated into a custom-designed haptic interface device.Various computer graphical techniques are also applied in the virtual gallbladder removal laparoscopic surgery training.The detailed techniques and the results of the simulations are described in this paper.

  14. Integrated Plasma Simulation of Ion Cyclotron and Lower Hybrid Range of Frequencies Actuators in Tokamaks

    Science.gov (United States)

    Bonoli, P. T.; Shiraiwa, S.; Wright, J. C.; Harvey, R. W.; Batchelor, D. B.; Berry, L. A.; Chen, Jin; Poli, F.; Kessel, C. E.; Jardin, S. C.

    2012-10-01

    Recent upgrades to the ion cyclotron RF (ICRF) and lower hybrid RF (LHRF) components of the Integrated Plasma Simulator [1] have made it possible to simulate LH current drive in the presence of ICRF minority heating and mode conversion electron heating. The background plasma is evolved in these simulations using the TSC transport code [2]. The driven LH current density profiles are computed using advanced ray tracing (GENRAY) and Fokker Planck (CQL3D) [3] components and predictions from GENRAY/CQL3D are compared with a ``reduced'' model for LHCD (the LSC [4] code). The ICRF TORIC solver is used for minority heating with a simplified (bi-Maxwellian) model for the non-thermal ion tail. Simulation results will be presented for LHCD in the presence of ICRF heating in Alcator C-Mod. [4pt] [1] D. Batchelor et al, Journal of Physics: Conf. Series 125, 012039 (2008).[0pt] [2] S. C. Jardin et al, J. Comp. Phys. 66, 481 (1986).[0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Meeting on Simulation and Modeling of Therm. Plasmas, Montreal, Canada (1992).[0pt] [4] D. Ignat et al, Nucl. Fus. 34, 837 (1994).[0pt] [5] M. Brambilla, Plasma Phys. and Cont. Fusion 41,1 (1999).

  15. Fast surrogate-assisted simulation-driven optimization of compact microwave hybrid couplers

    Science.gov (United States)

    Kurgan, Piotr; Koziel, Slawomir

    2016-07-01

    This work presents a robust methodology for expedited simulation-driven design optimization of compact microwave hybrid couplers. The technique relies on problem decomposition, and a bottom-up design strategy, starting from the level of basic building blocks of the coupler, and finishing with a tuning procedure that exploits a fast surrogate model of the entire structure. The latter is constructed by cascading local response surface approximations of coupler elementary elements. The cross-coupling effects within the structure are neglected in the first stage of the design process; however, they are accounted for in the tuning phase by means of space-mapping correction of the surrogate. The proposed approach is demonstrated through the design of a compact rat-race and two branch-line couplers. In all cases, the computational cost of the optimization process is very low and corresponds to just a few high-fidelity electromagnetic simulations of respective structures. Experimental validation is also provided.

  16. Atomistic-Continuum Hybrid Simulation of Heat Transfer between Argon Flow and Copper Plates

    CERN Document Server

    Mao, Yijin; Chen, C L

    2016-01-01

    A simulation work aiming to study heat transfer coefficient between argon fluid flow and copper plate is carried out based on atomistic-continuum hybrid method. Navier-Stokes equations for continuum domain are solved through the Pressure Implicit with Splitting of Operators (PISO) algorithm, and the atom evolution in molecular domain is solved through the Verlet algorithm. The solver is validated by solving Couette flow and heat conduction problems. With both momentum and energy coupling method applied, simulations on convection of argon flows between two parallel plates are performed. The top plate is kept as a constant velocity and has higher temperature, while the lower one, which is modeled with FCC copper lattices, is also fixed but has lower temperature. It is found that, heat transfer between argon fluid flow and copper plate in this situation is much higher than that at macroscopic when the flow is fully developed.

  17. A hybrid FEM-DEM approach to the simulation of fluid flow laden with many particles

    Science.gov (United States)

    Casagrande, Marcus V. S.; Alves, José L. D.; Silva, Carlos E.; Alves, Fábio T.; Elias, Renato N.; Coutinho, Alvaro L. G. A.

    2017-04-01

    In this work we address a contribution to the study of particle laden fluid flows in scales smaller than TFM (two-fluid models). The hybrid model is based on a Lagrangian-Eulerian approach. A Lagrangian description is used for the particle system employing the discrete element method (DEM), while a fixed Eulerian mesh is used for the fluid phase modeled by the finite element method (FEM). The resulting coupled DEM-FEM model is integrated in time with a subcycling scheme. The aforementioned scheme is applied in the simulation of a seabed current to analyze which mechanisms lead to the emergence of bedload transport and sediment suspension, and also quantify the effective viscosity of the seabed in comparison with the ideal no-slip wall condition. A simulation of a salt plume falling in a fluid column is performed, comparing the main characteristics of the system with an experiment.

  18. SOLAR WIND TURBULENCE FROM MHD TO SUB-ION SCALES: HIGH-RESOLUTION HYBRID SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Franci, Luca; Verdini, Andrea; Landi, Simone [Dipartimento di Fisica e Astronomia, Università di Firenze, Largo E. Fermi 2, I-50125 Firenze (Italy); Matteini, Lorenzo [Department of Physics, Imperial College London, London SW7 2AZ (United Kingdom); Hellinger, Petr [Astronomical Institute, AS CR, Bocni II/1401, CZ-14100 Prague (Czech Republic)

    2015-05-10

    We present results from a high-resolution and large-scale hybrid (fluid electrons and particle-in-cell protons) two-dimensional numerical simulation of decaying turbulence. Two distinct spectral regions (separated by a smooth break at proton scales) develop with clear power-law scaling, each one occupying about a decade in wavenumbers. The simulation results simultaneously exhibit several properties of the observed solar wind fluctuations: spectral indices of the magnetic, kinetic, and residual energy spectra in the magnetohydrodynamic (MHD) inertial range along with a flattening of the electric field spectrum, an increase in magnetic compressibility, and a strong coupling of the cascade with the density and the parallel component of the magnetic fluctuations at sub-proton scales. Our findings support the interpretation that in the solar wind, large-scale MHD fluctuations naturally evolve beyond proton scales into a turbulent regime that is governed by the generalized Ohm’s law.

  19. Hybrid Molecular and Spin Dynamics Simulations for Ensembles of Magnetic Nanoparticles for Magnetoresistive Systems.

    Science.gov (United States)

    Teich, Lisa; Schröder, Christian

    2015-11-13

    The development of magnetoresistive sensors based on magnetic nanoparticles which are immersed in conductive gel matrices requires detailed information about the corresponding magnetoresistive properties in order to obtain optimal sensor sensitivities. Here, crucial parameters are the particle concentration, the viscosity of the gel matrix and the particle structure. Experimentally, it is not possible to obtain detailed information about the magnetic microstructure, i.e., orientations of the magnetic moments of the particles that define the magnetoresistive properties, however, by using numerical simulations one can study the magnetic microstructure theoretically, although this requires performing classical spin dynamics and molecular dynamics simulations simultaneously. Here, we present such an approach which allows us to calculate the orientation and the trajectory of every single magnetic nanoparticle. This enables us to study not only the static magnetic microstructure, but also the dynamics of the structuring process in the gel matrix itself. With our hybrid approach, arbitrary sensor configurations can be investigated and their magnetoresistive properties can be optimized.

  20. Aspect of Dynamic Simulation and Experimental Research Studies on Hybrid Pneumatic Power System

    Directory of Open Access Journals (Sweden)

    K. David Huang

    2010-01-01

    Full Text Available A Hybrid Pneumatic Power System (HPPS has been developed for several years with the major aim of reducing the vehicle fuel consumption, environment pollution and enhancing the vehicle performance as well. Comparing with the conventional hybrid system, HPPS replaces the battery's electrochemical energy with a high-pressure air storage tank and enables the internal combustion engine (ICE to function at its sweet spot. Besides, the HPPS, which effectively merges both the high-pressure air flow from the storage tank and the recycled exhaust flow from the ICE, thereby increases the thermal efficiency of the ICE and transforms the merged flow energy into mechanical energy using a high-efficiency turbine. This paper focuses on the major research process into HPPSs, including overall dynamic simulation and experimental validation. By using the simulation tool ITI-Sim, this research demonstrates an experiment which can be operated precisely according to the requirements of various driving conditions under which a car actually runs on the road in accordance with the regulated running vehicle test mode. HPPS is expected to increase the performance of the entire system from 15% to 39%, and is likely to replace the traditional system in the coming years.

  1. A conservative and a hybrid early rejection schemes for accelerating Monte Carlo molecular simulation

    KAUST Repository

    Kadoura, Ahmad Salim

    2014-03-17

    Molecular simulation could provide detailed description of fluid systems when compared to experimental techniques. They can also replace equations of state; however, molecular simulation usually costs considerable computational efforts. Several techniques have been developed to overcome such high computational costs. In this paper, two early rejection schemes, a conservative and a hybrid one, are introduced. In these two methods, undesired configurations generated by the Monte Carlo trials are rejected earlier than it would when using conventional algorithms. The methods are tested for structureless single-component Lennard-Jones particles in both canonical and NVT-Gibbs ensembles. The computational time reduction for both ensembles is observed at a wide range of thermodynamic conditions. Results show that computational time savings are directly proportional to the rejection rate of Monte Carlo trials. The proposed conservative scheme has shown to be successful in saving up to 40% of the computational time in the canonical ensemble and up to 30% in the NVT-Gibbs ensemble when compared to standard algorithms. In addition, it preserves the exact Markov chains produced by the Metropolis scheme. Further enhancement for NVT-Gibbs ensemble is achieved by combining this technique with the bond formation early rejection one. The hybrid method achieves more than 50% saving of the central processing unit (CPU) time.

  2. Kinematic Modelling and Control Simulation for 1PS+3TPS Type Hybrid Machine Tool

    Institute of Scientific and Technical Information of China (English)

    FAN Shouwen; WANG Xiaobing; HUANG Hongzhong

    2006-01-01

    A structure scheme for a novel hybrid machine tool (HMT) is proposed in this paper. In the scheme, a 4-DOFs 1PS+3TPS type spatial hybrid mechanism is utilized as main feed mechanism, with assistance of a two direction movable worktable, multi-coordinates NC machining can be realized. In the main feed mechanism, fixed platform is connected with moving platform by three TPS driving links and one PS driving link, one translation DOF and three rotation DOFs can be achieved by it. This type HMT enjoys some advantages over its conventional counterparts:large workspace,good dexterity,etc. Closed form inverse displacement analysis model and inverse kinematic model for main feed mechanism are established. A fuzzy PID control scheme for machining control of HMTs with high tracking precision is proposed aiming at highly nonlinear, tightly coupled and uncertain characteristic of HMTs. Simulation researches for fuzzy PID control of HMTs are carried out. Simulation Results demonstrate the effectiveness and the Robostness of the fuzzy PID controller.

  3. Interaction of Enceladus's Water Plume with Saturnian Magnetosphere via Hybrid Numerical Simulations

    Science.gov (United States)

    Somr, J.; Travnicek, P. M.; Stverak, S.; Khurana, K. K.; Hellinger, P.; Dougherty, M. K.

    2008-12-01

    Several close Cassini flybys of the Santurnian moon Enceladus provided direct in situ measurements of neutral water molecules escaping from the surface showing their interaction with the ambient plasma environment. Cassini measurements indicate Enceladus to act as an obstacle to the magnetized Saturnian plasma flow resulting in an effect of field line draping. Ionization of escaping neutrals by way of charge exchange with the ambient plasma produces fresh ions which are picked up by the Saturnian magnetosphere. The Saturnian co-rotating plasma flow therefore slows down and the ambient magnetic field is affected. We study these local plasma interaction of Enceladus and its neutral water plume with the Saturnian magnetosphere by using a full 3D hybrid code numerical simulation. The results of our model are subsequently compared with Cassini observations. Since a complete and accurate description of Enceladus surroundings is still missing, the initialialization of our simulations is based on currently published estimations. However, by use the hybrid code we are able to recover very similar magnetic field signatures as some of those realy observed by Cassini spacecraft.

  4. Modeling, simulation, and concept studies of a fuel cell hybrid electric vehicle powertrain

    Energy Technology Data Exchange (ETDEWEB)

    Oezbek, Markus

    2010-03-29

    This thesis focuses on the development of a fuel cell-based hybrid electric powertrain for smaller (2 kW) hybrid electric vehicles (HEVs). A Hardware-in-the-Loop test rig is designed and built with the possibility to simulate any load profile for HEVs in a realistic environment, whereby the environment is modeled. Detailed simulation models of the test rig are developed and validated to real physical components and control algorithms are designed for the DC/DC-converters and the fuel cell system. A state-feedback controller is developed for the DC/DC-converters where the state-space averaging method is used for the development. For the fuel cells, a gain-scheduling controller based on state feedback is developed and compared to two conventional methods. The design process of an HEV with regard to a given load profile is introduced with comparison between SuperCaps and batteries. The HEV is also evaluated with an introduction to different power management concepts with regard to fuel consumption, dynamics, and fuel cell deterioration rate. The power management methods are implemented in the test rig and compared. (orig.)

  5. Using field theory to construct hybrid particle-continuum simulation schemes with adaptive resolution for soft matter systems

    OpenAIRE

    Qi, Shuanhu; Behringer, Hans; Schmid, Friederike

    2013-01-01

    We develop a multiscale hybrid scheme for simulations of soft condensed matter systems, which allows one to treat the system at the particle level in selected regions of space, and at the continuum level elsewhere. It is derived systematically from an underlying particle-based model by field theoretic methods. Particles in different representation regions can switch representations on the fly, controlled by a spatially varying tuning function. As a test case, the hybrid scheme is applied to s...

  6. Comparative analysis of RISAT-1 and simulated RADARSAT-2 hybrid polarimetric SAR data for different land features

    OpenAIRE

    Kumar, V; S Rao, Y.

    2014-01-01

    The purpose of this study is to compare the performance of first hybrid polarimetric spaceborne satellite RISAT-1 data and simulated hybrid polarimetric data from quad-pol RADARSAT-2 data for different land use land cover (LULC) classes. The present study compares Stokes (g0, g1, g2 and g3) and its decomposed parameters (m, chi, delta and CPR) for satellite data acquired from RISAT- 1 and RADARSAT-2 over Vijayawada, Andhra Pradesh, India. Further, backscattering coefficients are also...

  7. Simulation of a Pneumatic Hybrid Powertrain with VVT in GT-Power and Comparison with Experimental Data

    OpenAIRE

    Trajkovic, Sasa; Tunestål, Per; Johansson, Bengt

    2009-01-01

    In the study presented in this paper, experimental data from a pneumatic hybrid has been compared to the results from a simulation of the engine in GT-Power. The engine in question is a single-cylinder Scania D12 diesel engine, which has been converted to work as a pneumatic hybrid. The base engine model, provided by Scania, is made in GT-Power and it is based on the same engine configuration as the one used during real engine testing. During pneumatic hybrid operation the engine can be us...

  8. Transient Simulation Of A Solar-Hybrid Tower Power Plant With Open Volumetric Receiver At The Location Barstow

    OpenAIRE

    2013-01-01

    In this work the transient simulations of four hybrid solar tower power plant concepts with open-volumetric receiver technology for a location in Barstow-Daggett, USA, are presented. The open-volumetric receiver uses ambient air as heat transfer fluid and the hybridization is realized with a gas turbine. The Rankine cycle is heated by solar-heated air and/or by the gas turbine’s flue gases. The plant can be operated in solar-only, hybrid parallel or combined cycle-only mode as well a...

  9. Clarifying the learning experiences of healthcare professionals with in situ and off-site simulation-based medical education: a qualitative study

    NARCIS (Netherlands)

    Sorensen, J.L.; Navne, L.E.; Martin, H.M.; Ottesen, B.; Albrecthsen, C.K.; Pedersen, B.W.; Kjaergaard, H.; Vleuten, C. van der

    2015-01-01

    OBJECTIVE: To examine how the setting in in situ simulation (ISS) and off-site simulation (OSS) in simulation-based medical education affects the perceptions and learning experience of healthcare professionals. DESIGN: Qualitative study using focus groups and content analysis. PARTICIPANTS: Twenty-f

  10. Analysis of Winske-Daughton 3D Electromagnetic Particle Simulation of Ion Ring Generated Lower Hybrid Turbulence

    CERN Document Server

    Rudakov, Leonid; Mithaiwala, Manish; Ganguli, Gurudas

    2012-01-01

    Using electromagnetic particle-in-cell simulations Winske and Daughton [Phys Plasmas, 19, 072109, 2012] have recently demonstrated that the nonlinear evolution of a wave turbulence initiated by cold ion ring beam is vastly different in three dimensions than in two dimensions. We further analyze the Winske-Daughton three dimensional simulation data and show that the nonlinear induced scattering by thermal plasma particles is crucial for understanding the evolution of lower hybrid/whistler wave turbulence as described in the simulation.

  11. Apical transportation of manual NiTi instruments and a hybrid technique in severely curved simulated canals

    OpenAIRE

    Aurenaila Nascimento Gonçalves; Matheus Franco da Frota; Emilio Carlos Sponchiado Júnior; Fredson Marcio Acris de Carvalho; Lucas da Fonseca Roberti Garcia; André Augusto Franco Marques

    2015-01-01

    Aim: To evaluate the apical transportation induced by two instrumentation techniques in severely curved simulated canals. Materials and Methods: Forty simulated canals were divided into two groups (n = 20), according to the following instrumentation techniques: ProTaper Universal Manual System and a hybrid technique. The simulated canals in the ProTaper group were prepared following the technique recommended by the manufacturer: SX files in the cervical third of the root canal and S1, S2,...

  12. Hybridization of Genetic Algorithm with Parallel Implementation of Simulated Annealing for Job Shop Scheduling

    Directory of Open Access Journals (Sweden)

    Thamilselvan Rakkiannan

    2012-01-01

    Full Text Available Problem statement: The Job Shop Scheduling Problem (JSSP is observed as one of the most difficult NP-hard, combinatorial problem. The problem consists of determining the most efficient schedule for jobs that are processed on several machines. Approach: In this study Genetic Algorithm (GA is integrated with the parallel version of Simulated Annealing Algorithm (SA is applied to the job shop scheduling problem. The proposed algorithm is implemented in a distributed environment using Remote Method Invocation concept. The new genetic operator and a parallel simulated annealing algorithm are developed for solving job shop scheduling. Results: The implementation is done successfully to examine the convergence and effectiveness of the proposed hybrid algorithm. The JSS problems tested with very well-known benchmark problems, which are considered to measure the quality of proposed system. Conclusion/Recommendations: The empirical results show that the proposed genetic algorithm with simulated annealing is quite successful to achieve better solution than the individual genetic or simulated annealing algorithm."

  13. Molecular dynamics and Monte Carlo hybrid simulation for fuzzy tungsten nanostructure formation

    Science.gov (United States)

    Ito, A. M.; Takayama, A.; Oda, Y.; Tamura, T.; Kobayashi, R.; Hattori, T.; Ogata, S.; Ohno, N.; Kajita, S.; Yajima, M.; Noiri, Y.; Yoshimoto, Y.; Saito, S.; Takamura, S.; Murashima, T.; Miyamoto, M.; Nakamura, H.

    2015-07-01

    For the purposes of long-term use of tungsten divertor walls, the formation process of the fuzzy tungsten nanostructure induced by exposure to the helium plasma was studied. In the present paper, the fuzzy nanostructure's formation has been successfully reproduced by the new hybrid simulation method in which the deformation of the tungsten material due to pressure of the helium bubbles was simulated by the molecular dynamics and the diffusion of the helium atoms was simulated by the random walk based on the Monte Carlo method. By the simulation results, the surface height of the fuzzy nanostructure increased only when helium retention was under the steady state. It was proven that the growth of the fuzzy nanostructure was brought about by bursting of the helium bubbles. Moreover, we suggest the following key formation mechanisms of the fuzzy nanostructure: (1) lifting in which the surface lifted up by the helium bubble changes into a convexity, (2) bursting by which the region of the helium bubble changes into a concavity, and (3) the difference of the probability of helium retention by which the helium bubbles tend to appear under the concavity. Consequently, the convex-concave surface structure was enhanced and grew to create the fuzzy nanostructure.

  14. Transient simulation of regression rate on thrust regulation process in hybrid rocket motor

    Directory of Open Access Journals (Sweden)

    Tian Hui

    2014-12-01

    Full Text Available The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas. Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB (hydroxyl-terminated polybutadiene hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.

  15. Simulation and Optimization of Air-Cooled PEMFC Stack for Lightweight Hybrid Vehicle Application

    Directory of Open Access Journals (Sweden)

    Jingming Liang

    2015-01-01

    Full Text Available A model of 2 kW air-cooled proton exchange membrane fuel cell (PEMFC stack has been built based upon the application of lightweight hybrid vehicle after analyzing the characteristics of heat transfer of the air-cooled stack. Different dissipating models of the air-cooled stack have been simulated and an optimal simulation model for air-cooled stack called convection heat transfer (CHT model has been figured out by applying the computational fluid dynamics (CFD software, based on which, the structure of the air-cooled stack has been optimized by adding irregular cooling fins at the end of the stack. According to the simulation result, the temperature of the stack has been equally distributed, reducing the cooling density and saving energy. Finally, the 2 kW hydrogen-air air-cooled PEMFC stack is manufactured and tested by comparing the simulation data which is to find out its operating regulations in order to further optimize its structure.

  16. Transient simulation of regression rate on thrust regulation process in hybrid rocket motor

    Institute of Scientific and Technical Information of China (English)

    Tian Hui; Li Yijie; Zeng Peng

    2014-01-01

    The main goal of this paper is to study the characteristics of regression rate of solid grain during thrust regulation process. For this purpose, an unsteady numerical model of regression rate is established. Gas–solid coupling is considered between the solid grain surface and combustion gas. Dynamic mesh is used to simulate the regression process of the solid fuel surface. Based on this model, numerical simulations on a H2O2/HTPB (hydroxyl-terminated polybutadiene) hybrid motor have been performed in the flow control process. The simulation results show that under the step change of the oxidizer mass flow rate condition, the regression rate cannot reach a stable value instantly because the flow field requires a short time period to adjust. The regression rate increases with the linear gain of oxidizer mass flow rate, and has a higher slope than the relative inlet function of oxidizer flow rate. A shorter regulation time can cause a higher regression rate during regulation process. The results also show that transient calculation can better simulate the instantaneous regression rate in the operation process.

  17. PHOTO: A computer simulation program for photovoltaic and hybrid energy systems. Document and user's guide

    Science.gov (United States)

    Manninen, L. M.; Lund, P. D.; Virkkula, A.

    1990-11-01

    The version 3.0 is described of the program package PHOTO for the simulation and sizing of hybrid power systems (photovoltaic and wind power plants) on IBM PC, XT, AT, PS/2 and compatibles. The minimum memory requirement is 260 kB. Graphical output is created with HALO'88 graphics subroutine library. In the simulation model, special attention is given to the battery storage unit. A backup generator can also be included in the system configuration. The dynamic method developed uses accurate system component models accounting for component interactions and losses in e.g. wiring and diodes. The photovoltaic array can operate in a maximum power mode or in a clamped voltage mode together with the other subsystems. Various control strategies can also be considered. Individual subsystem models were verified against real measurements. Illustrative simulation example is also discussed. The presented model can be used to simulate various system configurations accurately and evaluate system performance, such as energy flows and power losses in photovoltaic array, wind generator, backup generator, wiring, diodes, maximum power point tracking device, inverter and battery. Energy cost is also an important consideration.

  18. Microstructure in two- and three-dimensional hybrid simulations of perpendicular collisionless shocks

    Science.gov (United States)

    Burgess, David; Hellinger, Petr; Gingell, Imogen; Trávníček, Pavel M.

    2016-08-01

    Supercritical collisionless perpendicular shocks have an average macrostructure determined primarily by the dynamics of ions specularly reflected at the magnetic ramp. Within the overall macrostructure, instabilities, both linear and nonlinear, generate fluctuations and microstructure. To identify the sources of such microstructure, high-resolution two- and three-dimensional simulations have been carried out using the hybrid method, wherein the ions are treated as particles and the electron response is modelled as a massless fluid. We confirm the results of earlier two-dimensional (2-D) simulations showing both field-parallel aligned propagating fluctuations and fluctuations carried by the reflected-gyrating ions. In addition, it is shown that, for 2-D simulations of the shock coplanarity plane, the presence of short-wavelength fluctuations in all magnetic components is associated with the ion Weibel instability driven at the upstream edge of the foot by the reflected-gyrating ions. In 3-D simulations we show for the first time that the dominant microstructure is due to a coupling between field-parallel propagating fluctuations in the ramp and the motion of the reflected ions. This results in a pattern of fluctuations counter-propagating across the surface of the shock at an angle inclined to the magnetic field direction, due to a combination of field-parallel motion at the Alfvén speed of the ramp and motion in the sense of gyration of the reflected ions.

  19. Simulation of a Wall-Bounded Flow using a Hybrid LES/RAS Approach with Turbulence Recycling

    Science.gov (United States)

    Quinlan, Jesse R.; Mcdaniel, James; Baurle, Robert A.

    2012-01-01

    Simulations of a supersonic recessed-cavity flow are performed using a hybrid large-eddy/ Reynolds-averaged simulation approach utilizing an inflow turbulence recycling procedure and hybridized inviscid flux scheme. Calorically perfect air enters the three-dimensional domain at a free stream Mach number of 2.92. Simulations are performed to assess grid sensitivity of the solution, efficacy of the turbulence recycling, and effect of the shock sensor used with the hybridized inviscid flux scheme. Analysis of the turbulent boundary layer upstream of the rearward-facing step for each case indicates excellent agreement with theoretical predictions. Mean velocity and pressure results are compared to Reynolds-averaged simulations and experimental data for each case, and these comparisons indicate good agreement on the finest grid. Simulations are repeated on a coarsened grid, and results indicate strong grid density sensitivity. The effect of turbulence recycling on the solution is illustrated by performing coarse grid simulations with and without inflow turbulence recycling. Two shock sensors, one of Ducros and one of Larsson, are assessed for use with the hybridized inviscid flux reconstruction scheme.

  20. Comparison of meaningful learning characteristics in simulated nursing practice after traditional versus computer-based simulation method: a qualitative videography study.

    Science.gov (United States)

    Poikela, Paula; Ruokamo, Heli; Teräs, Marianne

    2015-02-01

    Nursing educators must ensure that nursing students acquire the necessary competencies; finding the most purposeful teaching methods and encouraging learning through meaningful learning opportunities is necessary to meet this goal. We investigated student learning in a simulated nursing practice using videography. The purpose of this paper is to examine how two different teaching methods presented students' meaningful learning in a simulated nursing experience. The 6-hour study was divided into three parts: part I, general information; part II, training; and part III, simulated nursing practice. Part II was delivered by two different methods: a computer-based simulation and a lecture. The study was carried out in the simulated nursing practice in two universities of applied sciences, in Northern Finland. The participants in parts II and I were 40 first year nursing students; 12 student volunteers continued to part III. Qualitative analysis method was used. The data were collected using video recordings and analyzed by videography. The students who used a computer-based simulation program were more likely to report meaningful learning themes than those who were first exposed to lecture method. Educators should be encouraged to use computer-based simulation teaching in conjunction with other teaching methods to ensure that nursing students are able to receive the greatest educational benefits. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Hybrid data acquisition and processing strategies with increased throughput and selectivity: pSMART analysis for global qualitative and quantitative analysis.

    Science.gov (United States)

    Prakash, Amol; Peterman, Scott; Ahmad, Shadab; Sarracino, David; Frewen, Barbara; Vogelsang, Maryann; Byram, Gregory; Krastins, Bryan; Vadali, Gouri; Lopez, Mary

    2014-12-05

    Data-dependent acquisition (DDA) and data-independent acquisition strategies (DIA) have both resulted in improved understanding of proteomics samples. Both strategies have advantages and disadvantages that are well-published, where DDA is typically applied for deep discovery and DIA may be used to create sample records. In this paper, we present a hybrid data acquisition and processing strategy (pSMART) that combines the strengths of both techniques and provides significant benefits for qualitative and quantitative peptide analysis. The performance of pSMART is compared to published DIA strategies in an experiment that allows the objective assessment of DIA performance with respect to interrogation of previously acquired MS data. The results of this experiment demonstrate that pSMART creates fewer decoy hits than a standard DIA strategy. Moreover, we show that pSMART is more selective, sensitive, and reproducible than either standard DIA or DDA strategies alone.

  2. Multiple methods for multiple futures: Integrating qualitative scenario planning and quantitative simulation modeling for natural resource decision making

    Science.gov (United States)

    Symstad, Amy; Fisichelli, Nicholas A.; Miller, Brian; Rowland, Erika; Schuurman, Gregor W.

    2017-01-01

    Scenario planning helps managers incorporate climate change into their natural resource decision making through a structured “what-if” process of identifying key uncertainties and potential impacts and responses. Although qualitative scenarios, in which ecosystem responses to climate change are derived via expert opinion, often suffice for managers to begin addressing climate change in their planning, this approach may face limits in resolving the responses of complex systems to altered climate conditions. In addition, this approach may fall short of the scientific credibility managers often require to take actions that differ from current practice. Quantitative simulation modeling of ecosystem response to climate conditions and management actions can provide this credibility, but its utility is limited unless the modeling addresses the most impactful and management-relevant uncertainties and incorporates realistic management actions. We use a case study to compare and contrast management implications derived from qualitative scenario narratives and from scenarios supported by quantitative simulations. We then describe an analytical framework that refines the case study’s integrated approach in order to improve applicability of results to management decisions. The case study illustrates the value of an integrated approach for identifying counterintuitive system dynamics, refining understanding of complex relationships, clarifying the magnitude and timing of changes, identifying and checking the validity of assumptions about resource responses to climate, and refining management directions. Our proposed analytical framework retains qualitative scenario planning as a core element because its participatory approach builds understanding for both managers and scientists, lays the groundwork to focus quantitative simulations on key system dynamics, and clarifies the challenges that subsequent decision making must address.

  3. Accuracy Evaluation Method for Electromechanical-electromagnetic Hybrid Simulation%机电-电磁混合仿真精度评估方法研究

    Institute of Scientific and Technical Information of China (English)

    房钊; 陶顺; 杨洋; 陈鹏伟; 肖湘宁

    2016-01-01

    Electromechanical-electromagnetic hybrid simulation can both do electromechanical transient simulation for the large-scale complex power grid and do electromagnetic transient simulation for a local network. It achieves harmonization on simulation scale and simulation accuracy. Whether the simulation results can accurately reflect the real situation will determine the reliability of the simulation results. This paper proposes a multiple time quantum, multiple locations and multiple variables three-level accuracy evaluation system, which can give quantitative value and qualitative interpretation for electromechanical-electromagnetic hybrid simulation. First of all, this paper introduces the basic principles and the relevant indicators of two typical feature extraction algorithms of power system simulation, which are prony method and feature selective validation. Then taking into account the properties of each object observations in electromechanical-electromagnetic hybrid simulation, the object observation is divided into three categories: electromagnetic system observables, the interface state observables and electromechanical system observables. By combining the two methods, a hierarchical accuracy evaluation system is set up. Finally, through evaluating the differences between the results of the two current sources hybrid simulation and full electromagnetic simulation, the applicability of the proposed accuracy evaluation system is verified.%机电-电磁混合仿真既能够对大规模复杂电网进行机电暂态仿真,也可对局部网络进行电磁暂态仿真,实现仿真规模和仿真精度的协调统一,其仿真结果反映真实情况的程度,决定仿真结果的可信度,通过一种多时间、多位置和多物理量的3 级精度评估体系,定量和定性描述机电-电磁混合仿真结果的精度.首先,介绍 Prony 分析法和特征选择验证这两种典型特征量提取算法的基本原理及相关指标;然后,根据机电-电

  4. The split system approach to managing time in simulations of hybrid systems having continuous and discrete event components

    Energy Technology Data Exchange (ETDEWEB)

    Nutaro, James J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuruganti, Phani Teja [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Protopopescu, Vladimir A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shankar, Mallikarjun [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2012-02-08

    The efficient and accurate management of time in simulations of hybrid models is an outstanding engineering problem. General a priori knowledge about the dynamic behavior of the hybrid system (i.e. essentially continuous, essentially discrete, or 'truly hybrid') facilitates this task. Indeed, for essentially discrete and essentially continuous systems, existing software packages can be conveniently used to perform quite sophisticated and satisfactory simulations. The situation is different for 'truly hybrid' systems, for which direct application of existing software packages results in a lengthy design process, cumbersome software assemblies, inaccurate results, or some combination of these independent of the designer's a priori knowledge about the system's structure and behavior. The main goal of this paper is to provide a methodology whereby simulation designers can use a priori knowledge about the hybrid model's structure to build a straightforward, efficient, and accurate simulator with existing software packages. The proposed methodology is based on a formal decomposition and re-articulation of the hybrid system; this is the main theoretical result of the paper. To set the result in the right perspective, we briefly review the essentially continuous and essentially discrete approaches, which are illustrated with typical examples. Then we present our new, split system approach, first in a general formal context, then in three more specific guises that reflect the viewpoints of three main communities of hybrid system researchers and practitioners. For each of these variants we indicate an implementation path. Our approach is illustrated with an archetypal problem of power grid control.

  5. Simulations of hybrid system varying solar radiation and microturbine response time

    Directory of Open Access Journals (Sweden)

    Yolanda Fernández Ribaya

    2015-07-01

    Full Text Available Hybrid power systems, such as combinations of renewable power sources with intermittent power production and non-renewable power sources, theoretically increase the reliability and thus integration of renewable sources in the electrical system. However, a recent increase in the number of hybrid installations has sparked interest in the effects of their connection to the grid, especially in remote areas. This paper analyses a photovoltaic-gas microturbine hybrid system dimensioned to be installed in La Paz (Mexico.The research presented in this paper studies and quantifies the effects on the total electric power produced, varying both the solar radiation and the gas microturbine response time. The gas microturbine and the photovoltaic panels are modelled using Matlab/Simulink software, obtaining a platform where different tests to simulate real conditions have been executed. They consist of diverse ramps of irradiance that replicate solar radiation variations, and different microturbine response times reproduced by the time constants of a first order transfer function that models the microturbine dynamic response. The results obtained show that when radiation varies quickly it does not produce significant differences in the power guarantee or the microturbine gas consumption, to any microturbine response time. However, these two parameters are highly variable with smooth radiance variations. The maximum total power variation decreases greatly as the radiation variation gets lower. In addition, by decreasing the microturbine response time, it is possible to appreciably increase the power guarantee although the maximum power variation and gas consumption increase. Only in cases of low radiation variation is there no appreciable difference in the maximum power variation obtained by the different turbine response times.

  6. Simulations of hybrid system varying solar radiation and microturbine response time

    Science.gov (United States)

    Fernández Ribaya, Yolanda; Álvarez, Eduardo; Paredes Sánchez, José Pablo; Xiberta Bernat, Jorge

    2015-07-01

    Hybrid power systems, such as combinations of renewable power sources with intermittent power production and non-renewable power sources, theoretically increase the reliability and thus integration of renewable sources in the electrical system. However, a recent increase in the number of hybrid installations has sparked interest in the effects of their connection to the grid, especially in remote areas. This paper analyses a photovoltaic-gas microturbine hybrid system dimensioned to be installed in La Paz (Mexico).The research presented in this paper studies and quantifies the effects on the total electric power produced, varying both the solar radiation and the gas microturbine response time. The gas microturbine and the photovoltaic panels are modelled using Matlab/Simulink software, obtaining a platform where different tests to simulate real conditions have been executed. They consist of diverse ramps of irradiance that replicate solar radiation variations, and different microturbine response times reproduced by the time constants of a first order transfer function that models the microturbine dynamic response. The results obtained show that when radiation varies quickly it does not produce significant differences in the power guarantee or the microturbine gas consumption, to any microturbine response time. However, these two parameters are highly variable with smooth radiance variations. The maximum total power variation decreases greatly as the radiation variation gets lower. In addition, by decreasing the microturbine response time, it is possible to appreciably increase the power guarantee although the maximum power variation and gas consumption increase. Only in cases of low radiation variation is there no appreciable difference in the maximum power variation obtained by the different turbine response times.

  7. Simulations of hybrid system varying solar radiation and microturbine response time

    Energy Technology Data Exchange (ETDEWEB)

    Fernández Ribaya, Yolanda, E-mail: fernandezryolanda@uniovi.es; Álvarez, Eduardo; Paredes Sánchez, José Pablo; Xiberta Bernat, Jorge [Department of Energy E.I.M.E.M., University of Oviedo. 13 Independencia Street 2" n" d floor, 36004, Oviedo (Spain)

    2015-07-15

    Hybrid power systems, such as combinations of renewable power sources with intermittent power production and non-renewable power sources, theoretically increase the reliability and thus integration of renewable sources in the electrical system. However, a recent increase in the number of hybrid installations has sparked interest in the effects of their connection to the grid, especially in remote areas. This paper analyses a photovoltaic-gas microturbine hybrid system dimensioned to be installed in La Paz (Mexico).The research presented in this paper studies and quantifies the effects on the total electric power produced, varying both the solar radiation and the gas microturbine response time. The gas microturbine and the photovoltaic panels are modelled using Matlab/Simulink software, obtaining a platform where different tests to simulate real conditions have been executed. They consist of diverse ramps of irradiance that replicate solar radiation variations, and different microturbine response times reproduced by the time constants of a first order transfer function that models the microturbine dynamic response. The results obtained show that when radiation varies quickly it does not produce significant differences in the power guarantee or the microturbine gas consumption, to any microturbine response time. However, these two parameters are highly variable with smooth radiance variations. The maximum total power variation decreases greatly as the radiation variation gets lower. In addition, by decreasing the microturbine response time, it is possible to appreciably increase the power guarantee although the maximum power variation and gas consumption increase. Only in cases of low radiation variation is there no appreciable difference in the maximum power variation obtained by the different turbine response times.

  8. Qualitative and quantitative determination of YiXinShu Tablet using ultra high performance liquid chromatography with Q Exactive hybrid quadrupole orbitrap high-resolution accurate mass spectrometry.

    Science.gov (United States)

    Sun, Zhi; Li, Zhuolun; Zuo, Lihua; Wang, Zhenhui; Zhou, Lin; Shi, Yingying; Kang, Jian; Zhu, Zhenfeng; Zhang, Xiaojian

    2017-08-24

    To clarify and quantify the chemical profile of YiXinShu Tablet rapidly, a feasible and accurate strategy was developed by applying ultra high performance liquid chromatography with Q Exactive hybrid quadrupole orbitrap high-resolution accurate mass spectrometry. A total of 105 components were identified, including 25 phenanthraquinones, 11 lactones, 19 lignans, 24 acids and 26 other compounds. Among them, 26 major compounds were unambiguously detected by comparing with reference standards. And 19 of these compounds in three batches of YiXinShu Tablet were selected for quantitative determination. (Z)-Ligustilide, salvianic acid A, salvianolic acid A, salvianolic acid B and rosmarinic acid were abundant in these three batches with contents over 1.000 mg/g. The established analysis methods were examined to be accurate and feasible. The results show that the ultra high performance liquid chromatography with Q Exactive hybrid quadrupole orbitrap high-resolution accurate mass spectrometry method has a powerful qualitative ability and promising quantitative application. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  9. High-order Hybridized Discontinuous Galerkin methods for Large-Eddy Simulation

    Science.gov (United States)

    Fernandez, Pablo; Nguyen, Ngoc-Cuong; Peraire, Jaime

    2016-11-01

    With the increase in computing power, Large-Eddy Simulation emerges as a promising technique to improve both knowledge of complex flow physics and reliability of flow predictions. Most LES works, however, are limited to simple geometries and low Reynolds numbers due to high computational cost. While most existing LES codes are based on 2nd-order finite volume schemes, the efficient and accurate prediction of complex turbulent flows may require a paradigm shift in computational approach. This drives a growing interest in the development of Discontinuous Galerkin (DG) methods for LES. DG methods allow for high-order, conservative implementations on complex geometries, and offer opportunities for improved sub-grid scale modeling. Also, high-order DG methods are better-suited to exploit modern HPC systems. In the spirit of making them more competitive, researchers have recently developed the hybridized DG methods that result in reduced computational cost and memory footprint. In this talk we present an overview of high-order hybridized DG methods for LES. Numerical accuracy, computational efficiency, and SGS modeling issues are discussed. Numerical results up to Re=460k show rapid grid convergence and excellent agreement with experimental data at moderate computational cost.

  10. Recent Developments on Hybrid Time-Frequency Numerical Simulation Techniques for RF and Microwave Applications

    Directory of Open Access Journals (Sweden)

    Jorge F. Oliveira

    2013-01-01

    Full Text Available This paper reviews some of the promising doors that functional analysis techniques have recently opened in the field of electronic circuit simulation. Because of the modulated nature of radio frequency (RF signals, the corresponding electronic circuits seem to operate in a slow time scale for the aperiodic information and another, much faster, time scale for the periodic carrier. This apparent multirate behavior can be appropriately described using partial differential equations (PDEs within a bivariate framework, which can be solved in an efficient way using hybrid time-frequency techniques. With these techniques, the aperiodic information dimension is treated in the discrete time domain, while the periodic carrier dimension is processed in the frequency domain, in which the solution is evaluated within a space of harmonically related sinusoidal functions. The objective of this paper is thus to provide a general overview on the most important hybrid time-frequency techniques, as the ones found in commercial tools or the ones recently published in the literature.

  11. A general hybrid radiation transport scheme for star formation simulations on an adaptive grid

    Energy Technology Data Exchange (ETDEWEB)

    Klassen, Mikhail; Pudritz, Ralph E. [Department of Physics and Astronomy, McMaster University 1280 Main Street W, Hamilton, ON L8S 4M1 (Canada); Kuiper, Rolf [Max Planck Institute for Astronomy Königstuhl 17, D-69117 Heidelberg (Germany); Peters, Thomas [Institut für Computergestützte Wissenschaften, Universität Zürich Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Banerjee, Robi; Buntemeyer, Lars, E-mail: klassm@mcmaster.ca [Hamburger Sternwarte, Universität Hamburg Gojenbergsweg 112, D-21029 Hamburg (Germany)

    2014-12-10

    Radiation feedback plays a crucial role in the process of star formation. In order to simulate the thermodynamic evolution of disks, filaments, and the molecular gas surrounding clusters of young stars, we require an efficient and accurate method for solving the radiation transfer problem. We describe the implementation of a hybrid radiation transport scheme in the adaptive grid-based FLASH general magnetohydrodyanmics code. The hybrid scheme splits the radiative transport problem into a raytracing step and a diffusion step. The raytracer captures the first absorption event, as stars irradiate their environments, while the evolution of the diffuse component of the radiation field is handled by a flux-limited diffusion solver. We demonstrate the accuracy of our method through a variety of benchmark tests including the irradiation of a static disk, subcritical and supercritical radiative shocks, and thermal energy equilibration. We also demonstrate the capability of our method for casting shadows and calculating gas and dust temperatures in the presence of multiple stellar sources. Our method enables radiation-hydrodynamic studies of young stellar objects, protostellar disks, and clustered star formation in magnetized, filamentary environments.

  12. A General Hybrid Radiation Transport Scheme for Star Formation Simulations on an Adaptive Grid

    Science.gov (United States)

    Klassen, Mikhail; Kuiper, Rolf; Pudritz, Ralph E.; Peters, Thomas; Banerjee, Robi; Buntemeyer, Lars

    2014-12-01

    Radiation feedback plays a crucial role in the process of star formation. In order to simulate the thermodynamic evolution of disks, filaments, and the molecular gas surrounding clusters of young stars, we require an efficient and accurate method for solving the radiation transfer problem. We describe the implementation of a hybrid radiation transport scheme in the adaptive grid-based FLASH general magnetohydrodyanmics code. The hybrid scheme splits the radiative transport problem into a raytracing step and a diffusion step. The raytracer captures the first absorption event, as stars irradiate their environments, while the evolution of the diffuse component of the radiation field is handled by a flux-limited diffusion solver. We demonstrate the accuracy of our method through a variety of benchmark tests including the irradiation of a static disk, subcritical and supercritical radiative shocks, and thermal energy equilibration. We also demonstrate the capability of our method for casting shadows and calculating gas and dust temperatures in the presence of multiple stellar sources. Our method enables radiation-hydrodynamic studies of young stellar objects, protostellar disks, and clustered star formation in magnetized, filamentary environments.

  13. Hybrid-PIC Computer Simulation of the Plasma and Erosion Processes in Hall Thrusters

    Science.gov (United States)

    Hofer, Richard R.; Katz, Ira; Mikellides, Ioannis G.; Gamero-Castano, Manuel

    2010-01-01

    HPHall software simulates and tracks the time-dependent evolution of the plasma and erosion processes in the discharge chamber and near-field plume of Hall thrusters. HPHall is an axisymmetric solver that employs a hybrid fluid/particle-in-cell (Hybrid-PIC) numerical approach. HPHall, originally developed by MIT in 1998, was upgraded to HPHall-2 by the Polytechnic University of Madrid in 2006. The Jet Propulsion Laboratory has continued the development of HPHall-2 through upgrades to the physical models employed in the code, and the addition of entirely new ones. Primary among these are the inclusion of a three-region electron mobility model that more accurately depicts the cross-field electron transport, and the development of an erosion sub-model that allows for the tracking of the erosion of the discharge chamber wall. The code is being developed to provide NASA science missions with a predictive tool of Hall thruster performance and lifetime that can be used to validate Hall thrusters for missions.

  14. Dynamic Modeling and Motion Simulation for A Winged Hybrid-Driven Underwater Glider

    Institute of Scientific and Technical Information of China (English)

    WANG Shu-xin; SUN Xiu-jun; WANG Yan-hui; WU Jian-guo; WANG Xiao-ming

    2011-01-01

    PETREL,a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV(autonomous underwater vehicle).It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile.In this paper,theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration.In addition,due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes,the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced,and the tailored dynamic equations of the hybrid glider are formulated.Moreover,the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials.

  15. Dynamic Simulation and Exergo-Economic Optimization of a Hybrid Solar–Geothermal Cogeneration Plant

    Directory of Open Access Journals (Sweden)

    Francesco Calise

    2015-04-01

    Full Text Available This paper presents a dynamic simulation model and a parametric analysis of a solar-geothermal hybrid cogeneration plant based on an Organic Rankine Cycle (ORC powered by a medium-enthalpy geothermal resource and a Parabolic Trough Collector solar field. The fluid temperature supplying heat to the ORC varies continuously as a function of the solar irradiation, affecting both the electrical and thermal energies produced by the system. Thus, a dynamic simulation was performed. The ORC model, developed in Engineering Equation Solver, is based on zero-dimensional energy and mass balances and includes specific algorithms to evaluate the off-design system performance. The overall simulation model of the solar-geothermal cogenerative plant was implemented in the TRNSYS environment. Here, the ORC model is imported, whereas the models of the other components of the system are developed on the basis of literature data. Results are analyzed on different time bases presenting energetic, economic and exergetic performance data. Finally, a rigorous optimization has been performed to determine the set of system design/control parameters minimizing simple payback period and exergy destruction rate. The system is profitable when a significant amount of the heat produced is consumed. The highest irreversibilities are due to the solar field and to the heat exchangers.

  16. Parametric identification of a servo-hydraulic actuator for real-time hybrid simulation

    Science.gov (United States)

    Qian, Yili; Ou, Ge; Maghareh, Amin; Dyke, Shirley J.

    2014-10-01

    In a typical Real-time Hybrid Simulation (RTHS) setup, servo-hydraulic actuators serve as interfaces between the computational and physical substructures. Time delay introduced by actuator dynamics and complex interaction between the actuators and the specimen has detrimental effects on the stability and accuracy of RTHS. Therefore, a good understanding of servo-hydraulic actuator dynamics is a prerequisite for controller design and computational simulation of RTHS. This paper presents an easy-to-use parametric identification procedure for RTHS users to obtain re-useable actuator parameters for a range of payloads. The critical parameters in a linearized servo-hydraulic actuator model are optimally obtained from genetic algorithms (GA) based on experimental data collected from various specimen mass/stiffness combinations loaded to the target actuator. The actuator parameters demonstrate convincing convergence trend in GA. A key feature of this parametric modeling procedure is its re-usability under different testing scenarios, including different specimen mechanical properties and actuator inner-loop control gains. The models match well with experimental results. The benefit of the proposed parametric identification procedure has been demonstrated by (1) designing an H∞ controller with the identified system parameters that significantly improves RTHS performance; and (2) establishing an analysis and computational simulation of a servo-hydraulic system that help researchers interpret system instability and improve design of experiments.

  17. Assessment of a Hybrid Continuous/Discontinuous Galerkin Finite Element Code for Geothermal Reservoir Simulations

    Science.gov (United States)

    Xia, Yidong; Podgorney, Robert; Huang, Hai

    2017-03-01

    FALCON (Fracturing And Liquid CONvection) is a hybrid continuous/discontinuous Galerkin finite element geothermal reservoir simulation code based on the MOOSE (Multiphysics Object-Oriented Simulation Environment) framework being developed and used for multiphysics applications. In the present work, a suite of verification and validation (V&V) test problems for FALCON was defined to meet the design requirements, and solved to the interests of enhanced geothermal system modeling and simulation. The intent for this test problem suite is to provide baseline comparison data that demonstrates the performance of FALCON solution methods. The test problems vary in complexity from a single mechanical or thermal process, to coupled thermo-hydro-mechanical processes in geological porous medium. Numerical results obtained by FALCON agreed well with either the available analytical solutions or experimental data, indicating the verified and validated implementation of these capabilities in FALCON. Whenever possible, some form of solution verification has been attempted to identify sensitivities in the solution methods, and suggest best practices when using the FALCON code.

  18. A hybrid Boundary Element Unstructured Transmission-line (BEUT) method for accurate 2D electromagnetic simulation

    Science.gov (United States)

    Simmons, Daniel; Cools, Kristof; Sewell, Phillip

    2016-11-01

    Time domain electromagnetic simulation tools have the ability to model transient, wide-band applications, and non-linear problems. The Boundary Element Method (BEM) and the Transmission Line Modeling (TLM) method are both well established numerical techniques for simulating time-varying electromagnetic fields. The former surface based method can accurately describe outwardly radiating fields from piecewise uniform objects and efficiently deals with large domains filled with homogeneous media. The latter volume based method can describe inhomogeneous and non-linear media and has been proven to be unconditionally stable. Furthermore, the Unstructured TLM (UTLM) enables modelling of geometrically complex objects by using triangular meshes which removes staircasing and unnecessary extensions of the simulation domain. The hybridization of BEM and UTLM which is described in this paper is named the Boundary Element Unstructured Transmission-line (BEUT) method. It incorporates the advantages of both methods. The theory and derivation of the 2D BEUT method is described in this paper, along with any relevant implementation details. The method is corroborated by studying its correctness and efficiency compared to the traditional UTLM method when applied to complex problems such as the transmission through a system of Luneburg lenses and the modelling of antenna radomes for use in wireless communications.

  19. Simulation of flow in the microcirculation using a hybrid Lattice-Boltzman and Finite Element algorithm

    Science.gov (United States)

    Gonzalez-Mancera, Andres; Gonzalez Cardenas, Diego

    2014-11-01

    Flow in the microcirculation is highly dependent on the mechanical properties of the cells suspended in the plasma. Red blood cells have to deform in order to pass through the smaller sections in the microcirculation. Certain deceases change the mechanical properties of red blood cells affecting its ability to deform and the rheological behaviour of blood. We developed a hybrid algorithm based on the Lattice-Boltzmann and Finite Element methods to simulate blood flow in small capillaries. Plasma was modeled as a Newtonian fluid and the red blood cells' membrane as a hyperelastic solid. The fluid-structure interaction was handled using the immersed boundary method. We simulated the flow of plasma with suspended red blood cells through cylindrical capillaries and measured the pressure drop as a function of the membrane's rigidity. We also simulated the flow through capillaries with a restriction and identify critical properties for which the suspended particles are unable to flow. The algorithm output was verified by reproducing certain common features of flow int he microcirculation such as the Fahraeus-Lindqvist effect.

  20. Simulation of generalized hybrid model for solar and wind power generation

    Directory of Open Access Journals (Sweden)

    Vankadara Sampath kumar

    2015-03-01

    Full Text Available Due to urbanization, globalization and industrialization the demand for energy is rapidly increasing allows the world and India is not an exception. Out of all energies electrical energy is playing a major role in developed as well as developing countries. The energy is mostly produced by fossil fuels which are developing day his is to by day .they also produce lot of pollutants which totally damage the environment the alternative to this is to encourage renewable energy source. Now days the energy production at domestic level is becoming popular with the help of solar and wind energies . These technologies are widely used now days in the present paper an attempt has been made to simulate a generalized hybrid model including solar and wind.

  1. Further validation of the hybrid particle-mesh method for vortex shedding flow simulations

    Directory of Open Access Journals (Sweden)

    Lee Seung-Jae

    2015-11-01

    Full Text Available This is the continuation of a numerical study on vortex shedding from a blunt trailing-edge of a hydrofoil. In our previous work (Lee et al., 2015, numerical schemes for efficient computations were successfully implemented; i.e. multiple domains, the approximation of domain boundary conditions using cubic spline functions, and particle-based domain decomposition for better load balancing. In this study, numerical results through a hybrid particle-mesh method which adopts the Vortex-In-Cell (VIC method and the Brinkman penalization model are further rigorously validated through comparison to experimental data at the Reynolds number of 2 × 106. The effects of changes in numerical parameters are also explored herein. We find that the present numerical method enables us to reasonably simulate vortex shedding phenomenon, as well as turbulent wakes of a hydrofoil.

  2. Simulation of hydrogen bubble growth in tungsten by a hybrid model

    Science.gov (United States)

    Sang, Chaofeng; Sun, Jizhong; Bonnin, Xavier; Wang, L.; Wang, Dezhen

    2015-08-01

    A two dimensional hybrid code (HIIPC-MC) joining rate-theory and Monte Carlo (MC) methods is developed in this work. We evaluate the cascade-coalescence mechanism contribution to the bubble growth by MC. First, effects of the starting radius and solute deuterium concentration on the bubble growth are studied; then the impacts of the wall temperature and implantation ion flux on the bubble growth are assessed. The simulation indicates that the migration-coalescence of the bubbles and the high pressure inside the bubbles are the main driving forces for the bubble growth, and that neglect of the migration and coalescence would lead to an underestimation of the bubble growth or blistering.

  3. Hybrid models for the simulation of microstructural evolution influenced by coupled, multiple physical processes

    Energy Technology Data Exchange (ETDEWEB)

    Tikare, Veena [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hernandez-Rivera, Efrain [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Madison, Jonathan D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Holm, Elizabeth Ann [Carnegie Mellon Univ., Pittsburgh, PA (United States); Patterson, Burton R. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering; Homer, Eric R. [Brigham Young Univ., Provo, UT (United States). Dept. of Mechanical Engineering

    2013-09-01

    Most materials microstructural evolution processes progress with multiple processes occurring simultaneously. In this work, we have concentrated on the processes that are active in nuclear materials, in particular, nuclear fuels. These processes are coarsening, nucleation, differential diffusion, phase transformation, radiation-induced defect formation and swelling, often with temperature gradients present. All these couple and contribute to evolution that is unique to nuclear fuels and materials. Hybrid model that combines elements from the Potts Monte Carlo, phase-field models and others have been developed to address these multiple physical processes. These models are described and applied to several processes in this report. An important feature of the models developed are that they are coded as applications within SPPARKS, a Sandiadeveloped framework for simulation at the mesoscale of microstructural evolution processes by kinetic Monte Carlo methods. This makes these codes readily accessible and adaptable for future applications.

  4. Proton temperature-anisotropy-driven instabilities in weakly collisional plasmas: Hybrid simulations

    CERN Document Server

    Hellinger, Petr

    2014-01-01

    Kinetic instabilities in weakly collisional, high beta plasmas are investigated using two-dimensional hybrid expanding box simulations with Coulomb collisions modeled through the Langevin equation (corresponding to the Fokker-Planck one). The expansion drives a parallel or perpendicular temperature anisotropy (depending on the orientation of the ambient magnetic field). For the chosen parameters the Coulomb collisions are important with respect to the driver but are not strong enough to keep the system stable with respect to instabilities driven by the proton temperature anisotropy. In the case of the parallel temperature anisotropy the dominant oblique fire hose instability efficiently reduces the anisotropy in a quasilinear manner. In the case of the perpendicular temperature anisotropy the dominant mirror instability generates coherent compressive structures which scatter protons and reduce the temperature anisotropy. For both the cases the instabilities generate temporarily enough wave energy so that the ...

  5. Accelerated Degradation for Hardware in the Loop Simulation of Fuel Cell-Gas Turbine Hybrid System

    DEFF Research Database (Denmark)

    Abreu-Sepulveda, Maria A.; Harun, Nor Farida; Hackett, Gregory

    2015-01-01

    The U.S. Department of Energy (DOE)-National Energy Technology Laboratory (NETL) in Morgantown, WV has developed the hybrid performance (HyPer) project in which a solid oxide fuel cell (SOFC) one-dimensional (1D), real-time operating model is coupled to a gas turbine hardware system by utilizing...... hardware-in-the-loop simulation. To assess the long-term stability of the SOFC part of the system, electrochemical degradation due to operating conditions such as current density and fuel utilization have been incorporated into the SOFC model and successfully recreated in real time. The mathematical...... expression for degradation rate was obtained through the analysis of empirical voltage versus time plots for different current densities and fuel utilizations....

  6. Two-dimensional Hybrid Simulations of Kinetic Plasma Turbulence: Current and Vorticity vs Proton Temperature

    CERN Document Server

    Franci, Luca; Matteini, Lorenzo; Verdini, Andrea; Landi, Simone

    2016-01-01

    Proton temperature anisotropies between the directions parallel and perpendicular to the mean magnetic field are usually observed in the solar wind plasma. Here, we employ a high-resolution hybrid particle-in-cell simulation in order to investigate the relation between spatial properties of the proton temperature and the peaks in the current density and in the flow vorticity. Our results indicate that, although regions where the proton temperature is enhanced and temperature anisotropies are larger correspond approximately to regions where many thin current sheets form, no firm quantitative evidence supports the idea of a direct causality between the two phenomena. On the other hand, quite a clear correlation between the behavior of the proton temperature and the out-of-plane vorticity is obtained.

  7. Fully implicit mixed-hybrid finite-element discretization for general purpose subsurface reservoir simulation

    Science.gov (United States)

    Abushaikha, Ahmad S.; Voskov, Denis V.; Tchelepi, Hamdi A.

    2017-10-01

    We present a new fully-implicit, mixed-hybrid, finite-element (MHFE) discretization scheme for general-purpose compositional reservoir simulation. The locally conservative scheme solves the coupled momentum and mass balance equations simultaneously, and the fluid system is modeled using a cubic equation-of-state. We introduce a new conservative flux approach for the mass balance equations for this fully-implicit approach. We discuss the nonlinear solution procedure for the proposed approach, and we present extensive numerical tests to demonstrate the convergence and accuracy of the MHFE method using tetrahedral elements. We also compare the method to other advanced discretization schemes for unstructured meshes and tensor permeability. Finally, we illustrate the applicability and robustness of the method for highly heterogeneous reservoirs with unstructured grids.

  8. Simulation of hydrogen bubble growth in tungsten by a hybrid model

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Chaofeng, E-mail: sang@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China); Sun, Jizhong [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China); Bonnin, Xavier [LSPM-CNRS, Université Paris 13, Sorbonne Paris Cité, Villetaneuse 93430 (France); Wang, L. [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Wang, Dezhen, E-mail: wangdez@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Ministry of Education), School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116024 (China)

    2015-08-15

    A two dimensional hybrid code (HIIPC-MC) joining rate-theory and Monte Carlo (MC) methods is developed in this work. We evaluate the cascade-coalescence mechanism contribution to the bubble growth by MC. First, effects of the starting radius and solute deuterium concentration on the bubble growth are studied; then the impacts of the wall temperature and implantation ion flux on the bubble growth are assessed. The simulation indicates that the migration-coalescence of the bubbles and the high pressure inside the bubbles are the main driving forces for the bubble growth, and that neglect of the migration and coalescence would lead to an underestimation of the bubble growth or blistering.

  9. Hybrid electrodynamics and kinetics simulation for electromagnetic wave propagation in weakly ionized hydrogen plasmas.

    Science.gov (United States)

    Chen, Qiang; Chen, Bin

    2012-10-01

    In this paper, a hybrid electrodynamics and kinetics numerical model based on the finite-difference time-domain method and lattice Boltzmann method is presented for electromagnetic wave propagation in weakly ionized hydrogen plasmas. In this framework, the multicomponent Bhatnagar-Gross-Krook collision model considering both elastic and Coulomb collisions and the multicomponent force model based on the Guo model are introduced, which supply a hyperfine description on the interaction between electromagnetic wave and weakly ionized plasma. Cubic spline interpolation and mean filtering technique are separately introduced to solve the multiscalar problem and enhance the physical quantities, which are polluted by numerical noise. Several simulations have been implemented to validate our model. The numerical results are consistent with a simplified analytical model, which demonstrates that this model can obtain satisfying numerical solutions successfully.

  10. Numerical Simulation for One Dimensional Steady Quasineutral Hybrid Model of Stationary Plasma Thruster

    Institute of Scientific and Technical Information of China (English)

    Yu Daren; Wu Zhiwen; Wu Xiaoling

    2005-01-01

    Based on the analysis of the physical mechanism of the Stationary Plasma Thruster (SPT), an integral equation describing the ion density of the steady SPT and the ion velocity distribution function at an arbitrary axial position of the steady SPT channel are derived. The integral equation is equivalent to the Vlasov equation, but the former is simpler than the latter. A one dimensional steady quasineutral hybrid model is established. In this model, ions are described by the above integral equation, and neutrals and electrons are described by hydrodynamic equations. The transferred equivalency to the differential equation and the integral equation, together with other equations, are solved by an ordinary differential equation (ODE) solver in the Matlab.The numerical simulation results show that under various circumstances, the ion average velocity would be different and needs to be deduced separately.

  11. Numerical simulation of droplet shapes in laser-MIG hybrid welding

    Science.gov (United States)

    Lei, Zhenglong; Ni, Longchang; Li, Bingwei; Zhang, Kezhao

    2017-02-01

    A three-dimensional finite element model based on minimum energy principle is developed to simulate the droplet transfer process in laser-MIG hybrid welding. The energy manifestations of all forces that determine droplet shapes are considered in this model, and the model has been used to predict droplet shapes. Offset of droplet centroid and critical additional axial acceleration are adopted to characterize the stability of droplet transfer. The calculated droplet shapes and offset of droplet centroid agree well with experimental results. It is found that increasing laser power or decreasing welding current would destabilize droplet transfer. Additional mechanical forces contribute to stable droplet transfer, and the positive effects of increased shielding gas flow rate on the stability of welding processes are subsequently verified.

  12. Adaptive multi-rate interface: development and experimental verification for real-time hybrid simulation

    DEFF Research Database (Denmark)

    Maghareh, Amin; Waldbjørn, Jacob Paamand; Dyke, Shirley J.;

    2016-01-01

    Real-time hybrid simulation (RTHS) is a powerful cyber-physical technique that is a relatively cost-effective method to perform global/local system evaluation of structural systems. A major factor that determines the ability of an RTHS to represent true system-level behavior is the fidelity...... it employs different time steps in the numerical and the physical substructures while including rate-transitioning to link the components appropriately. Typically, a higher-order numerical substructure model is solved at larger time intervals, and is coupled with a physical substructure that is driven...... frequency between the numerical and physical substructures and for input signals with high-frequency content. Further, it does not induce signal chattering at the coupling frequency. The effectiveness of AMRI is also verified experimentally....

  13. Hybrid simulation of a parallel collisionless shock in the Large Plasma Device

    CERN Document Server

    Weidl, M S; Jenko, F; Niemann, C

    2016-01-01

    We present two-dimensional hybrid kinetic/magnetohydrodynamic simulations of planned laser-ablation experiments in the Large Plasma Device (LAPD). Our results, based on parameters which have been validated in previous experiments, show that a parallel collisionless shock can begin forming within the available space. Carbon-debris ions that stream along the magnetic-field direction with a blow-off speed of four times the Alfven velocity excite strong magnetic fluctuations, eventually transfering part of their kinetic energy to the surrounding hydrogen ions. This acceleration and compression of the background plasma creates a shock front, which satisfies the Rankine-Hugoniot conditions and can therefore propagate on its own. Furthermore, we analyze the upstream turbulence and show that it is dominated by the right-hand resonant instability.

  14. IMPROVED PARAMETERIZATION OF WATER CLOUD MODEL FOR HYBRID-POLARIZED BACKSCATTER SIMULATION USING INTERACTION FACTOR

    Directory of Open Access Journals (Sweden)

    S. Chauhan

    2017-07-01

    Full Text Available The prime aim of this study was to assess the potential of semi-empirical water cloud model (WCM in simulating hybrid-polarized SAR backscatter signatures (RH and RV retrieved from RISAT-1 data and integrate the results into a graphical user interface (GUI to facilitate easy comprehension and interpretation. A predominant agricultural wheat growing area was selected in Mathura and Bharatpur districts located in the Indian states of Uttar Pradesh and Rajasthan respectively to carry out the study. The three-date datasets were acquired covering the crucial growth stages of the wheat crop. In synchrony, the fieldwork was organized to measure crop/soil parameters. The RH and RV backscattering coefficient images were extracted from the SAR data for all the three dates. The effect of four combinations of vegetation descriptors (V1 and V2 viz., LAI-LAI, LAI-Plant water content (PWC, Leaf water area index (LWAI-LWAI, and LAI-Interaction factor (IF on the total RH and RV backscatter was analyzed. The results revealed that WCM calibrated with LAI and IF as the two vegetation descriptors simulated the total RH and RV backscatter values with highest R2 of 0.90 and 0.85 while the RMSE was lowest among the other tested models (1.18 and 1.25 dB, respectively. The theoretical considerations and interpretations have been discussed and examined in the paper. The novelty of this work emanates from the fact that it is a first step towards the modeling of hybrid-polarized backscatter data using an accurately parameterized semi-empirical approach.

  15. Hybrid Broadband Ground-Motion Simulation Using Scenario Earthquakes for the Istanbul Area

    KAUST Repository

    Reshi, Owais A.

    2016-04-13

    Seismic design, analysis and retrofitting of structures demand an intensive assessment of potential ground motions in seismically active regions. Peak ground motions and frequency content of seismic excitations effectively influence the behavior of structures. In regions of sparse ground motion records, ground-motion simulations provide the synthetic seismic records, which not only provide insight into the mechanisms of earthquakes but also help in improving some aspects of earthquake engineering. Broadband ground-motion simulation methods typically utilize physics-based modeling of source and path effects at low frequencies coupled with high frequency semi-stochastic methods. I apply the hybrid simulation method by Mai et al. (2010) to model several scenario earthquakes in the Marmara Sea, an area of high seismic hazard. Simulated ground motions were generated at 75 stations using systematically calibrated model parameters. The region-specific source, path and site model parameters were calibrated by simulating a w4.1 Marmara Sea earthquake that occurred on November 16, 2015 on the fault segment in the vicinity of Istanbul. The calibrated parameters were then used to simulate the scenario earthquakes with magnitudes w6.0, w6.25, w6.5 and w6.75 over the Marmara Sea fault. Effects of fault geometry, hypocenter location, slip distribution and rupture propagation were thoroughly studied to understand variability in ground motions. A rigorous analysis of waveforms reveal that these parameters are critical for determining the behavior of ground motions especially in the near-field. Comparison of simulated ground motion intensities with ground-motion prediction quations indicates the need of development of the region-specific ground-motion prediction equation for Istanbul area. Peak ground motion maps are presented to illustrate the shaking in the Istanbul area due to the scenario earthquakes. The southern part of Istanbul including Princes Islands show high amplitudes

  16. Modeling, control, and simulation of grid connected intelligent hybrid battery/photovoltaic system using new hybrid fuzzy-neural method.

    Science.gov (United States)

    Rezvani, Alireza; Khalili, Abbas; Mazareie, Alireza; Gandomkar, Majid

    2016-07-01

    Nowadays, photovoltaic (PV) generation is growing increasingly fast as a renewable energy source. Nevertheless, the drawback of the PV system is its dependence on weather conditions. Therefore, battery energy storage (BES) can be considered to assist for a stable and reliable output from PV generation system for loads and improve the dynamic performance of the whole generation system in grid connected mode. In this paper, a novel topology of intelligent hybrid generation systems with PV and BES in a DC-coupled structure is presented. Each photovoltaic cell has a specific point named maximum power point on its operational curve (i.e. current-voltage or power-voltage curve) in which it can generate maximum power. Irradiance and temperature changes affect these operational curves. Therefore, the nonlinear characteristic of maximum power point to environment has caused to development of different maximum power point tracking techniques. In order to capture the maximum power point (MPP), a hybrid fuzzy-neural maximum power point tracking (MPPT) method is applied in the PV system. Obtained results represent the effectiveness and superiority of the proposed method, and the average tracking efficiency of the hybrid fuzzy-neural is incremented by approximately two percentage points in comparison to the conventional methods. It has the advantages of robustness, fast response and good performance. A detailed mathematical model and a control approach of a three-phase grid-connected intelligent hybrid system have been proposed using Matlab/Simulink.

  17. Qualitative comparison of soil erosion, runoff and infiltration coefficients using small portable rainfall simulators in Germany, Spain and France

    Science.gov (United States)

    Rodrigo Comino, Jesús; Iserloh, Thomas; Morvan, Xavier; Malam Issa, Oumarou; Naisse, Christophe; Keesstra, Saskia; Cerdà, Artemi; Prosdocimi, Massimo; Arnáez, José; Lasanta, Teodoro; Concepción Ramos, María; José Marqués, María; Ruiz Colmenero, Marta; Bienes, Ramón; Damián Ruiz Sinoga, José; Seeger, Manuel; Ries, Johannes B.

    2016-04-01

    Small portable rainfall simulators are considered as a useful tool to analyze soil erosion processes in cultivated lands. European research groups of Spain (Valencia, Málaga, Lleida, Madrid and La Rioja), France (Reims) or Germany (Trier) have used different rainfall simulators (varying in drop size distribution and fall velocities, kinetic energy, plot forms and sizes, and field of application)to study soil loss, surface flow, runoff and infiltration coefficients in different experimental plots (Valencia, Montes de Málaga, Penedès, Campo Real and La Rioja in Spain, Champagne in France and Mosel-Ruwer valley in Germany). The measurements and experiments developed by these research teams give an overview of the variety in the methodologies with rainfall simulations in studying the problem of soil erosion and describing the erosion features in different climatic environments, management practices and soil types. The aim of this study is: i) to investigate where, how and why researchers from different wine-growing regions applied rainfall simulations with successful results as a tool to measure soil erosion processes; ii) to make a qualitative comparison about the general soil erosion processes in European terroirs; iii) to demonstrate the importance of the development a standard method for soil erosion processes in vineyards, using rainfall simulators; iv) and to analyze the key factors that should be taken into account to carry out rainfall simulations. The rainfall simulations in all cases allowed knowing the infiltration capacity and the susceptibility of the soil to be detached and to generate sediment loads to runoff. Despite using small plots, the experiments were useful to analyze the influence of soil cover to reduce soil erosion and to make comparison between different locations or the influence of different soil characteristics.

  18. Analysis tools for simulation of hybrid systems; Herramientas de analisis para simulacion de sistemas hibridos

    Energy Technology Data Exchange (ETDEWEB)

    Guillen S, Omar; Mejia N, Fortino [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2005-07-01

    In order to facilitate and to simplify the development and analysis of a Hybrid System in reference to its design, construction, operation and maintenance, it turns out optimal to carry out the simulation of this one by means of software, with which a significant reduction in the investment costs is obtained. Given the mix of technology of electrical generation which is involved in a hybrid system, it is very important to have a tool integrated with specialized packages of calculation (software), that allow to carry out the simulation tasks of the operational functioning of these systems. Combined with the former, one must not fail to consider the operation characteristics, the facilities of the user, the clarity in the obtained results and the possibility of its validation with respect to prototypes orchestrated in field. Equally, it is necessary to consider the identification of tasks involved in relation to the place of installation of this electrification technology. At the moment, the hybrid systems technology still is in a stage of development in the international level, and exist important limitations as far as the methodology availability and engineering tools for the optimum design of these systems. With the development of this paper, it is intended to contribute to the advance of the technology and to count on own tools to solve the described series of problems. In this article are described the activities that more impact have in the design and development of hybrid systems, as well as the identification of variables, basic characteristics and form of validation of tools in the integration of a methodology for the simulation of these systems, facilitating their design and development. [Spanish] Para facilitar y simplificar el desarrollo y analisis de un Sistema Hibrido en lo que refiere a su diseno, construccion, operacion y mantenimiento, resulta optimo efectuar la simulacion de este por medio de un software, con lo que se obtiene una reduccien

  19. Lower Hybrid Current Drive Experiments on Alcator C-Mod: Comparison with Theory and Simulation

    Science.gov (United States)

    Bonoli, Paul

    2007-11-01

    Recently, lower hybrid current drive (LHCD) experiments have been carried out on Alcator C-Mod using an RF system consisting of 12 klystrons at 4.6 GHz, feeding a 4 x 22 waveguide array. Up to 900 kW of LH power has been coupled in the range1.6 PLH 0.3 [1]. We have simulated the LH current drive in these discharges using the combined ray tracing / 3D (r, v, v//) Fokker Planck code GENRAY -- CQL3D [2] and found similar current drive efficiencies. Measurements of nonthermal x-ray emission and electron cyclotron emission (ECE) confirm the presence of a significant fast electron population that varies with waveguide phasing and plasma density. Studies are currently underway to investigate the role of fast electron diffusion and full-wave effects such as diffractional broadening in determining the spatial and velocity space structure of the nonthermal electrons. The 3D (r, v, v//) electron distribution function from CQL3D has been used in synthetic diagnostic codes to simulate the measured hard x-ray and ECE emissions. Fast electron diffusion times have been inferred from x-ray data by employing a radial diffusion operator in CQL3D and determining the fast electron diffusivities that are required to reproduce the experimentally observed profiles of hard x-ray emission. Finally, we have been performing full-wave LH field simulations using the massively parallel TORIC --LH solver [3] in order to assess spatial and spectral broadening of the incident wave front that can result from diffraction and wave focusing effects. [1] R. Parker, Bull. Am. Phys. Soc. 51, 20 (2006). [2] R.W. Harvey and M. McCoy, ``The CQL3D Fokker Planck Code,'' Proc. IAEA Tech. Comm. Meeting on Simulation and Modeling of Thermonuclear Plasmas, Montreal, Canada, 1992. [3] J. C. Wright et al., Nucl. Fusion 45, 1411 (2005).

  20. Ultra-fast hybrid CPU-GPU multiple scatter simulation for 3-D PET.

    Science.gov (United States)

    Kim, Kyung Sang; Son, Young Don; Cho, Zang Hee; Ra, Jong Beom; Ye, Jong Chul

    2014-01-01

    Scatter correction is very important in 3-D PET reconstruction due to a large scatter contribution in measurements. Currently, one of the most popular methods is the so-called single scatter simulation (SSS), which considers single Compton scattering contributions from many randomly distributed scatter points. The SSS enables a fast calculation of scattering with a relatively high accuracy; however, the accuracy of SSS is dependent on the accuracy of tail fitting to find a correct scaling factor, which is often difficult in low photon count measurements. To overcome this drawback as well as to improve accuracy of scatter estimation by incorporating multiple scattering contribution, we propose a multiple scatter simulation (MSS) based on a simplified Monte Carlo (MC) simulation that considers photon migration and interactions due to photoelectric absorption and Compton scattering. Unlike the SSS, the MSS calculates a scaling factor by comparing simulated prompt data with the measured data in the whole volume, which enables a more robust estimation of a scaling factor. Even though the proposed MSS is based on MC, a significant acceleration of the computational time is possible by using a virtual detector array with a larger pitch by exploiting that the scatter distribution varies slowly in spatial domain. Furthermore, our MSS implementation is nicely fit to a parallel implementation using graphic processor unit (GPU). In particular, we exploit a hybrid CPU-GPU technique using the open multiprocessing and the compute unified device architecture, which results in 128.3 times faster than using a single CPU. Overall, the computational time of MSS is 9.4 s for a high-resolution research tomograph (HRRT) system. The performance of the proposed MSS is validated through actual experiments using an HRRT.

  1. Effect of mobile phase additives on qualitative and quantitative analysis of ginsenosides by liquid chromatography hybrid quadrupole-time of flight mass spectrometry.

    Science.gov (United States)

    Liang, Yan; Guan, Tianye; Zhou, Yuanyuan; Liu, Yanna; Xing, Lu; Zheng, Xiao; Dai, Chen; Du, Ping; Rao, Tai; Zhou, Lijun; Yu, Xiaoyi; Hao, Kun; Xie, Lin; Wang, Guangji

    2013-07-05

    This study was to systematically investigate the effect of mobile phase additives, including ammonia water, formic acid, acetic acid, ammonium chloride and water (as a control), on qualitative and quantitative analysis of fifteen representative ginsenosides based on liquid chromatography hybrid quadrupole-time of flight mass spectrometry (LC-Q-TOF/MS). To evaluate the influence of mobile phase additives on qualitative performance, the quality of the negative mode MS/MS spectra of ginsenosides produced by online LC-Q-TOF/MS analyses, particularly the numbers and intensities of fragment ions, were compared under different adduct ion states, and found to be strongly affected by the mobile phase additives. When 0.02% acetic acid was added in the mobile phase, the deprotonated ginsenosides ions produced the most abundant product ions, while almost no product ion was observed for the chlorinated ginsenoside ions when 0.1mM ammonium chloride was used as the mobile phase additive. On the other hand, sensitivity, linear range and precision were adopted to investigate the quantitative performance affected by different mobile phase additives. Validation results of the LC-Q-TOF/MS-based quantitative performance for ginsenosides showed that ammonium chloride not only provided the highest sensitivity for all the target analytes, but also dramatically improved the linear ranges, the intra-day and inter-day precisions comparing to the results obtained using other mobile phase additives. Importantly, the validated method, using 0.1mM ammonium chloride as the mobile phase additive, was successfully applied to the quantitative analysis of ginsenosides in rat plasma after intragastric administration of Ginsenoside Extract at 200mg/kg. In conclusion, 0.02% acetic acid was deemed to be the most suitable mobile phase additive for qualitative analysis of ginsenosides, and 0.1mM ammonium chloride in mobile phase could lead to the best quantitative performance. Our results reveal that

  2. Assessing the Impact of Policy Changes in the Icelandic Cod Fishery Using a Hybrid Simulation Model

    Directory of Open Access Journals (Sweden)

    Sigríður Sigurðardóttir

    2014-01-01

    Full Text Available Most of the Icelandic cod is caught in bottom trawlers or longliners. These two fishing methods are fundamentally different and have different economic, environmental, and even social effects. In this paper we present a hybrid-simulation framework to assess the impact of changing the ratio between cod quota allocated to vessels with longlines and vessels with bottom trawls. It makes use of conventional bioeconomic models and discrete event modelling and provides a framework for simulating life cycle assessment (LCA for a cod fishery. The model consists of two submodels, a system dynamics model describing the biological aspect of the fishery and a discrete event model for fishing activities. The model was run multiple times for different quota allocation scenarios and results are presented where different scenarios are presented in the three dimensions of sustainability: environmental, social, and economic. The optimal allocation strategy depends on weighing the three different factors. The results were encouraging first-steps towards a useful modelling method but the study would benefit greatly from better data on fishing activities.

  3. Hybrid Molecular and Spin Dynamics Simulations for Ensembles of Magnetic Nanoparticles for Magnetoresistive Systems

    Directory of Open Access Journals (Sweden)

    Lisa Teich

    2015-11-01

    Full Text Available The development of magnetoresistive sensors based on magnetic nanoparticles which are immersed in conductive gel matrices requires detailed information about the corresponding magnetoresistive properties in order to obtain optimal sensor sensitivities. Here, crucial parameters are the particle concentration, the viscosity of the gel matrix and the particle structure. Experimentally, it is not possible to obtain detailed information about the magnetic microstructure, i.e., orientations of the magnetic moments of the particles that define the magnetoresistive properties, however, by using numerical simulations one can study the magnetic microstructure theoretically, although this requires performing classical spin dynamics and molecular dynamics simulations simultaneously. Here, we present such an approach which allows us to calculate the orientation and the trajectory of every single magnetic nanoparticle. This enables us to study not only the static magnetic microstructure, but also the dynamics of the structuring process in the gel matrix itself. With our hybrid approach, arbitrary sensor configurations can be investigated and their magnetoresistive properties can be optimized.

  4. Assessing the impact of policy changes in the Icelandic cod fishery using a hybrid simulation model.

    Science.gov (United States)

    Sigurðardóttir, Sigríður; Johansson, Björn; Margeirsson, Sveinn; Viðarsson, Jónas R

    2014-01-01

    Most of the Icelandic cod is caught in bottom trawlers or longliners. These two fishing methods are fundamentally different and have different economic, environmental, and even social effects. In this paper we present a hybrid-simulation framework to assess the impact of changing the ratio between cod quota allocated to vessels with longlines and vessels with bottom trawls. It makes use of conventional bioeconomic models and discrete event modelling and provides a framework for simulating life cycle assessment (LCA) for a cod fishery. The model consists of two submodels, a system dynamics model describing the biological aspect of the fishery and a discrete event model for fishing activities. The model was run multiple times for different quota allocation scenarios and results are presented where different scenarios are presented in the three dimensions of sustainability: environmental, social, and economic. The optimal allocation strategy depends on weighing the three different factors. The results were encouraging first-steps towards a useful modelling method but the study would benefit greatly from better data on fishing activities.

  5. Hybrid Kinetic-Fluid Electromagnetic Simulations of Imploding High Energy Density Plasmas for IFE

    Science.gov (United States)

    Welch, Dale; Rose, Dave; Thoma, Carsten; Genoni, Thomas; Bruner, Nichelle; Clark, Robert; Stygar, William; Leeper, Ramon

    2011-10-01

    A new simulation technique is being developed to study high current and moderate density-radius product (ρR) z-pinch plasmas relevant to Inertial Fusion Energy (IFE). Fully kinetic, collisional, and electromagnetic simulations of the time evolution of up to 40-MA current (deuterium and DT) z-pinches, but with relatively low ρR, have yielded new insights into the mechanisms of neutron production. At fusion relevant conditions (ρR > 0.01 gm/cm2) , however, this technique requires a prohibitively large number of cells and particles. A new hybrid implicit technique has been developed that accurately describes high-density and magnetized imploding plasmas. The technique adapts a recently published algorithm, that enables accurate descriptions of highly magnetized particle orbits, to high density plasmas and also makes use of an improved kinetic particle remap technique. We will discuss the new technique, stable range of operation, and application to an IFE relevant z-pinch design at 60 MA. Work supported by Sandia National Laboratories.

  6. Handling performance control for hybrid 8-wheel-drive vehicle and simulation verification

    Science.gov (United States)

    Ni, Jun; Hu, Jibin

    2016-08-01

    In order to improve handling performance of a hybrid 8-Wheel-Drive vehicle, the handling performance control strategy was proposed. For armoured vehicle, besides handling stability in high speed, the minimum steer radius in low speed is also a key tactical and technical index. Based on that, the proposed handling performance control strategy includes 'Handling Stability' and 'Radius Minimization' control modes. In 'Handling Stability' control mode, 'Neutralsteer Radio' is defined to adjust the steering characteristics to satisfy different demand in different speed range. In 'Radius Minimization' control mode, the independent motors are controlled to provide an additional yaw moment to decrease the minimum steer radius. In order to verify the strategy, a simulation platform was built including engine and continuously variable transmission systems, generator and battery systems, independent motors and controllers systems, vehicle dynamic and tyre mechanical systems. The simulation results show that the handling performance of the vehicle can be enhanced significantly, and the minimum steer radius can be decreased by 20% which is significant improvement compared to the common level of main battle armoured vehicle around the world.

  7. Compact hybrid solar simulator with the spectral match beyond class A

    Science.gov (United States)

    Baguckis, Artūras; Novičkovas, Algirdas; Mekys, Algirdas; Tamošiūnas, Vincas

    2016-07-01

    A compact hybrid solar simulator with the spectral match beyond class A is proposed. Six types of high-power light-emitting diodes (LEDs) and tungsten halogen lamps in total were employed to obtain spectral match with IEC 60904-9 Ed.2.0 and ASTM E927-10(2015) standards. Nonuniformity of the irradiance was evaluated and 3-cm diameter. A theoretical analysis was performed to evaluate possible performance of our simulator in the case of GaInP/GaAs/GaInAsP/GaInAs four-junction tandem solar cells and AM1.5D (ASTM G173-03 standard) spectrum. Lack of ultraviolet radiation in comparison to standard spectrum leads to 6.94% reduction of short-circuit current, which could be remedied with 137% increase of the output from blue LEDs. Excess of infrared radiation from halogen lamps outside ranges specified by standards is expected to lead to ˜0.77% voltage increase.

  8. A New Hybrid Scheme for Simulations of Highly Collisional RF-Driven Plasmas

    CERN Document Server

    Eremin, Denis; Mussenbrock, Thomas

    2015-01-01

    This work describes a new 1D hybrid approach for modeling atmospheric pressure discharges featuring complex chemistry. In this approach electrons are described fully kinetically using Particle-In-Cell/Monte-Carlo (PIC/MCC) scheme, whereas the heavy species are modeled within a fluid description. Validity of the popular drift-diffusion approximation is verified against a "full" fluid model accounting for the ion inertia and a fully kinetic PIC/MCC code for ions as well as electrons. The fluid models require knowledge of the momentum exchange frequency and dependence of the ion mobilities on the electric field when the ions are in equilibrium with the latter. To this end an auxiliary Monte-Carlo scheme is constructed. It is demonstrated that the drift-diffusion approximation can overestimate ion transport in simulations of RF-driven discharges with heavy ion species operated in the $\\gamma$ mode at the atmospheric pressure or in all discharge simulations for lower pressures. This can lead to exaggerated plasma ...

  9. High-resolution hybrid simulations of kinetic plasma turbulence at proton scales

    CERN Document Server

    Franci, Luca; Matteini, Lorenzo; Verdini, Andrea; Hellinger, Petr

    2015-01-01

    We investigate properties of plasma turbulence from magneto-hydrodynamic (MHD) to sub-ion scales by means of two-dimensional, high-resolution hybrid particle-in-cell simulations. We impose an initial ambient magnetic field, perpendicular to the simulation box, and we add a spectrum of large-scale magnetic and kinetic fluctuations, with energy equipartition and vanishing correlation. Once the turbulence is fully developed, we observe a MHD inertial range, where the spectra of the perpendicular magnetic field and the perpendicular proton bulk velocity fluctuations exhibit power-law scaling with spectral indices of -5/3 and -3/2, respectively. This behavior is extended over a full decade in wavevectors and is very stable in time. A transition is observed around proton scales. At sub-ion scales, both spectra steepen, with the former still following a power law with a spectral index of ~-3. A -2.8 slope is observed in the density and parallel magnetic fluctuations, highlighting the presence of compressive effects ...

  10. Hybrid (kinetic-fluid) simulation scheme based on method of characteristics

    CERN Document Server

    Javaheri, N; Abbasi, H

    2015-01-01

    Certain features of the method of characteristics are of considerable interest in relation with Vlasov simulation [H. Abbasi {\\it et al}, Phys. Rev. E \\textbf{84}, 036702 (2011)]. A Vlasov simulation scheme of this kind can be recurrence free providing initial phase points in velocity space are set randomly. Naturally, less filtering of fine-structures (arising from grid spacing) is possible as there is now a smaller scale than the grid spacing that is average distance between two phase points. Its interpolation scheme is very simple in form and carried out with less operations. In our previous report, the simplest model (immobile ions) was considered to merely demonstrate the important features. Now, a hybrid model is introduced that solves the coupled Vlasov-Fluid-Poisson system self-consistently. A possible application of the code is the study of ion-acoustic (IA) soliton attributes. To this end, a collisionless plasma with hot electrons and cold positive ions is considered. For electrons, the collisionles...

  11. Simulated human patients and patient-centredness: The uncanny hybridity of nursing education, technology, and learning to care.

    Science.gov (United States)

    Ireland, Aileen V

    2017-01-01

    Positioned within a hybrid of the human and technology, professional nursing practice has always occupied a space that is more than human. In nursing education, technology is central in providing tools with which practice knowledge is mobilized so that students can safely engage with simulated human patients without causing harm to real people. However, while there is an increased emphasis on deploying these simulated humans as emissaries from person-centred care to demonstrate what it is like to care for real humans, the nature of what is really going on in simulation-what is real and what is simulated-is very rarely discussed and poorly understood. This paper explores how elements of postcolonial critical thought can aid in understanding the challenges of educating nurses to provide person-centred care within a healthcare culture that is increasingly reliant on technology. Because nursing education is itself a hybrid of real and simulated practice, it provides an appropriate case study to explore the philosophical question of technology in healthcare discourse, particularly as it relates to the relationship between the human patient and its uncanny simulated double. Drawing on postcolonial elements such as the uncanny, diaspora, hybridity, and créolité, the hybrid conditions of nursing education are examined in order to open up new possibilities of thinking about how learning to care is entangled with this technological space to assist in shaping professional knowledge of person-centred care. Considering these issues through a postcolonial lens opens up questions about the nature of the difficulty in using simulated human technologies in clinical education, particularly with the paradoxical aim of providing person-centred care within a climate that increasingly characterized as posthuman. © 2016 John Wiley & Sons Ltd.

  12. A hybrid formulation for the numerical simulation of condensed phase explosives

    Science.gov (United States)

    Michael, L.; Nikiforakis, N.

    2016-07-01

    In this article we present a new formulation and an associated numerical algorithm, for the simulation of combustion and transition to detonation of condensed-phase commercial- and military-grade explosives, which are confined by (or in general interacting with one or more) compliant inert materials. Examples include confined rate-stick problems and interaction of shock waves with gas cavities or solid particles in explosives. This formulation is based on an augmented Euler approach to account for the mixture of the explosive and its products, and a multi-phase diffuse interface approach to solve for the immiscible interaction between the mixture and the inert materials, so it is in essence a hybrid (augmented Euler and multi-phase) model. As such, it has many of the desirable features of the two approaches and, critically for our applications of interest, it provides the accurate recovery of temperature fields across all components. Moreover, it conveys a lot more physical information than augmented Euler, without the complexity of full multi-phase Baer-Nunziato-type models or the lack of robustness of augmented Euler models in the presence of more than two components. The model can sustain large density differences across material interfaces without the presence of spurious oscillations in velocity and pressure, and it can accommodate realistic equations of state and arbitrary (pressure- or temperature-based) reaction-rate laws. Under certain conditions, we show that the formulation reduces to well-known augmented Euler or multi-phase models, which have been extensively validated and used in practice. The full hybrid model and its reduced forms are validated against problems with exact (or independently-verified numerical) solutions and evaluated for robustness for rate-stick and shock-induced cavity collapse case-studies.

  13. Estimating qualitative parameters for assessment of body balance and arm function in a simulated ambulatory setting

    NARCIS (Netherlands)

    Meulen, van Fokke B.; Reenalda, Jasper; Veltink, Peter H.

    2013-01-01

    Continuous daily-life monitoring of balance control and arm function of stroke survivors in an ambulatory setting, is essential for optimal guidance of rehabilitation. In a simulated ambulatory setting, balance and arm function of seven stroke subjects is evaluated using on-body measurement systems

  14. Jovian plasma torus interaction with Europa. Plasma wake structure and effect of inductive magnetic field: 3D Hybrid kinetic simulation

    CERN Document Server

    Lipatov, A S; Paterson, W R; Sittler, E C; Hartle, R E; Simpson, D G

    2012-01-01

    The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect a to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo Orbiter mission, and for planning flyby and orbital measurements (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy et al., 2007; Shematovich et al., 2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream backgr...

  15. Further validation of artificial neural network-based emissions simulation models for conventional and hybrid electric vehicles.

    Science.gov (United States)

    Tóth-Nagy, Csaba; Conley, John J; Jarrett, Ronald P; Clark, Nigel N

    2006-07-01

    With the advent of hybrid electric vehicles, computer-based vehicle simulation becomes more useful to the engineer and designer trying to optimize the complex combination of control strategy, power plant, drive train, vehicle, and driving conditions. With the desire to incorporate emissions as a design criterion, researchers at West Virginia University have developed artificial neural network (ANN) models for predicting emissions from heavy-duty vehicles. The ANN models were trained on engine and exhaust emissions data collected from transient dynamometer tests of heavy-duty diesel engines then used to predict emissions based on engine speed and torque data from simulated operation of a tractor truck and hybrid electric bus. Simulated vehicle operation was performed with the ADVISOR software package. Predicted emissions (carbon dioxide [CO2] and oxides of nitrogen [NO(x)]) were then compared with actual emissions data collected from chassis dynamometer tests of similar vehicles. This paper expands on previous research to include different driving cycles for the hybrid electric bus and varying weights of the conventional truck. Results showed that different hybrid control strategies had a significant effect on engine behavior (and, thus, emissions) and may affect emissions during different driving cycles. The ANN models underpredicted emissions of CO2 and NO(x) in the case of a class-8 truck but were more accurate as the truck weight increased.

  16. HyCFS, a high-resolution shock capturing code for numerical simulation on hybrid computational clusters

    Science.gov (United States)

    Shershnev, Anton A.; Kudryavtsev, Alexey N.; Kashkovsky, Alexander V.; Khotyanovsky, Dmitry V.

    2016-10-01

    The present paper describes HyCFS code, developed for numerical simulation of compressible high-speed flows on hybrid CPU/GPU (Central Processing Unit / Graphical Processing Unit) computational clusters on the basis of full unsteady Navier-Stokes equations, using modern shock capturing high-order TVD (Total Variation Diminishing) and WENO (Weighted Essentially Non-Oscillatory) schemes on general curvilinear structured grids. We discuss the specific features of hybrid architecture and details of program implementation and present the results of code verification.

  17. Using simulation learning through academic-practice partnership to promote transition to clinical practice: a qualitative evaluation.

    Science.gov (United States)

    Liaw, Sok Ying; Palham, Sabrina; Chan, Sally Wai-Chi; Wong, Lai Fun; Lim, Fui Ping

    2015-05-01

    To explore the effect of an innovative simulation education programme on nursing students' transition-to-practice experiences. Academic-practice partnership is emerging as an important vehicle for improving nursing students' transition-to-practice. Using existing university resources, academic educators and alumni developed an innovative simulation educational programme known as the Simulated Professional Learning Environment (SIMPLE) to align the educational process with the realities of nursing practice. Educators and alumni collaborated to create and facilitate 15 hours of simulation sessions that comprised the learning platform for the SIMPLE programme. This was a descriptive qualitative study. Focus groups were conducted in 2012 with 22 final-year nursing students completing their transition-to-practice clinical practicum. The interview transcripts were analysed using content analysis. Three themes were identified from the analysis: 'experiencing the role of staff nurse'; 'knowing how to'; and 'learning from the 'seniors'. Experiencing the role of staff nurse in the programme showed the nursing students what to expect and how to prepare for their roles. Knowing how to focus on holistic patient care, manage 'difficult' clients and communicate with other healthcare professionals were the learning outcomes gained from the programme. Learning from the 'seniors' about hospital work processes positively influenced the nurses' transition-to-practice experiences. This study provides support for introducing the simulation education programme as an enhancement during nursing students' final year to improve their transition-to-practice experiences. A stronger collaborative relationship between academic educators and practising nurses could be further fostered by expanding this learning platform. © 2014 John Wiley & Sons Ltd.

  18. Hybrid Reynolds-Averaged/Large-Eddy Simulations of a Co-Axial Supersonic Free-Jet Experiment

    Science.gov (United States)

    Baurle, R. A.; Edwards, J. R.

    2009-01-01

    Reynolds-averaged and hybrid Reynolds-averaged/large-eddy simulations have been applied to a supersonic coaxial jet flow experiment. The experiment utilized either helium or argon as the inner jet nozzle fluid, and the outer jet nozzle fluid consisted of laboratory air. The inner and outer nozzles were designed and operated to produce nearly pressure-matched Mach 1.8 flow conditions at the jet exit. The purpose of the computational effort was to assess the state-of-the-art for each modeling approach, and to use the hybrid Reynolds-averaged/large-eddy simulations to gather insight into the deficiencies of the Reynolds-averaged closure models. The Reynolds-averaged simulations displayed a strong sensitivity to choice of turbulent Schmidt number. The baseline value chosen for this parameter resulted in an over-prediction of the mixing layer spreading rate for the helium case, but the opposite trend was noted when argon was used as the injectant. A larger turbulent Schmidt number greatly improved the comparison of the results with measurements for the helium simulations, but variations in the Schmidt number did not improve the argon comparisons. The hybrid simulation results showed the same trends as the baseline Reynolds-averaged predictions. The primary reason conjectured for the discrepancy between the hybrid simulation results and the measurements centered around issues related to the transition from a Reynolds-averaged state to one with resolved turbulent content. Improvements to the inflow conditions are suggested as a remedy to this dilemma. Comparisons between resolved second-order turbulence statistics and their modeled Reynolds-averaged counterparts were also performed.

  19. Study on Forward-Facing Model and Real-Time Simulation for a Series Hybrid Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Xudong Liu

    2011-10-01

    Full Text Available To shorten design period and reduce development costs, computer modeling and simulation is important for HEV design and development. In this paper, real-time simulation for a Series Hybrid Electric Vehicle (SHEV is made to verify its fuzzy logic control strategy based on dSPACE-DS1103 development kits. The whole real-time simulation schematic is designed and the vehicle forward-facing simulation model is set up. Modeling methods for the driver, controller and vehicle (includes engine, generator, motor, battery, etc. under MATLAB/Simulink environment are discussed in detail. Driver behavior is simulated by two potentiometers and introduced into the real-time system to realize close-loop control. A real-time monitoring interface is also developed to observe the experiment results. Experiment results show that the real-time simulation platform works well and the SHEV fuzzy logic control strategy is effective.

  20. Medical students' medication communication skills regarding drug prescription-a qualitative analysis of simulated physician-patient consultations.

    Science.gov (United States)

    Hauser, Katarina; Matthes, Jan

    2017-04-01

    Poor medication communication of physicians to patients is detrimental, e.g. for medication adherence. Reasons for physicians' deficits in medication communication may be unfavourable conditions in daily practice or already insufficient training during their (undergraduate) medical studies. We explored medical students' communication on new medications in simulated physician-patient conversations to identify actual deficits indicating apparent educational needs. Fifth year medical students attending a mandatory course at the University of Cologne had simulated physician-patient consultations aiming at drug prescription. In 2015, 21 consultations were recorded, transcribed and subjected to qualitative content analysis based on the method of inductive coding. Even essential information on drug therapy was often lacking (e.g. adverse effects, drug administration). Some aspects were addressed more frequently than others. This seemed to differ depending on the diagnosis underlying the particular treatment (acute event vs. chronic disease). The extent of information on drug treatments given in simulated physician-patient consultations varied significantly between students. Fifth year medical students showed appreciable deficits in communicating drug prescriptions to patients though there were remarkable inter-individual differences. Our findings suggest that communication on drug therapy to patients is no self-evolving skill. Thus, there is obviously a need for emphasizing medication communication in the training of medical students. Communication aids specifically aiming at medication communication might facilitate learning of adequate medication communication skills.

  1. Development of a Continuum Damage Mechanics Material Model of a Graphite-Kevlar(Registered Trademark) Hybrid Fabric for Simulating the Impact Response of Energy Absorbing Kevlar(Registered Trademark) Hybrid Fabric for Simulating the Impact Response of Energy Absorbing

    Science.gov (United States)

    Jackson, Karen E.; Fasanella, Edwin L.; Littell, Justin D.

    2017-01-01

    This paper describes the development of input properties for a continuum damage mechanics based material model, Mat 58, within LS-DYNA(Registered Trademark) to simulate the response of a graphite-Kevlar(Registered Trademark) hybrid plain weave fabric. A limited set of material characterization tests were performed on the hybrid graphite-Kevlar(Registered Trademark) fabric. Simple finite element models were executed in LS-DYNA(Registered Trademark) to simulate the material characterization tests and to verify the Mat 58 material model. Once verified, the Mat 58 model was used in finite element models of two composite energy absorbers: a conical-shaped design, designated the "conusoid," fabricated of four layers of hybrid graphite-Kevlar(Registered Trademark) fabric; and, a sinusoidal-shaped foam sandwich design, designated the "sinusoid," fabricated of the same hybrid fabric face sheets with a foam core. Dynamic crush tests were performed on components of the two energy absorbers, which were designed to limit average vertical accelerations to 25- to 40-g, to minimize peak crush loads, and to generate relatively long crush stroke values under dynamic loading conditions. Finite element models of the two energy absorbers utilized the Mat 58 model that had been verified through material characterization testing. Excellent predictions of the dynamic crushing response were obtained.

  2. 3D electrostatic gyrokinetic electron and fully kinetic ion simulation of lower-hybrid drift instability of Harris current sheet

    Science.gov (United States)

    Wang, Zhenyu; Lin, Yu; Wang, Xueyi; Tummel, Kurt; Chen, Liu

    2016-07-01

    The eigenmode stability properties of three-dimensional lower-hybrid-drift-instabilities (LHDI) in a Harris current sheet with a small but finite guide magnetic field have been systematically studied by employing the gyrokinetic electron and fully kinetic ion (GeFi) particle-in-cell (PIC) simulation model with a realistic ion-to-electron mass ratio mi/me . In contrast to the fully kinetic PIC simulation scheme, the fast electron cyclotron motion and plasma oscillations are systematically removed in the GeFi model, and hence one can employ the realistic mi/me . The GeFi simulations are benchmarked against and show excellent agreement with both the fully kinetic PIC simulation and the analytical eigenmode theory. Our studies indicate that, for small wavenumbers, ky, along the current direction, the most unstable eigenmodes are peaked at the location where k →.B → =0 , consistent with previous analytical and simulation studies. Here, B → is the equilibrium magnetic field and k → is the wavevector perpendicular to the nonuniformity direction. As ky increases, however, the most unstable eigenmodes are found to be peaked at k →.B → ≠0 . In addition, the simulation results indicate that varying mi/me , the current sheet width, and the guide magnetic field can affect the stability of LHDI. Simulations with the varying mass ratio confirm the lower hybrid frequency and wave number scalings.

  3. Learning health 'safety' within non-technical skills interprofessional simulation education: a qualitative study.

    Science.gov (United States)

    Gordon, Morris; Fell, Christopher W R; Box, Helen; Farrell, Michael; Stewart, Alison

    2017-01-01

    Healthcare increasingly recognises and focusses on the phenomena of 'safe practice' and 'patient safety.' Success with non-technical skills (NTS) training in other industries has led to widespread transposition to healthcare education, with communication and teamwork skills central to NTS frameworks. This study set out to identify how the context of interprofessional simulation learning influences NTS acquisition and development of 'safety' amongst learners. Participants receiving a non-technical skills (NTS) safety focussed training package were invited to take part in a focus group interview which set out to explore communication, teamwork, and the phenomenon of safety in the context of the learning experiences they had within the training programme. The analysis was aligned with a constructivist paradigm and took an interactive methodological approach. The analysis proceeded through three stages, consisting of open, axial, and selective coding, with constant comparisons taking place throughout each phase. Each stage provided categories that could be used to explore the themes of the data. Additionally, to ensure thematic saturation, transcripts of observed simulated learning encounters were then analysed. Six themes were established at the axial coding level, i.e., analytical skills, personal behaviours, communication, teamwork, context, and pedagogy. Underlying these themes, two principal concepts emerged, namely: intergroup contact anxiety - as both a result of and determinant of communication - and teamwork, both of which must be considered in relation to context. These concepts have subsequently been used to propose a framework for NTS learning. This study highlights the role of intergroup contact anxiety and teamwork as factors in NTS behaviour and its dissipation through interprofessional simulation learning. Therefore, this should be a key consideration in NTS education. Future research is needed to consider the role of the affective non

  4. Hybrid modeling of the lower corona using Faraday rotation observations and a MHD thermodynamic simulation

    Science.gov (United States)

    Wexler, David B.; Hollweg, Joseph V.; Jensen, Elizabeth; Lionello, Roberto; Macneice, Peter J.; Coster, Anthea J.

    2017-08-01

    simulations with transcoronal radio observations allows improved characterization of the lower corona. This hybrid approach potentially paves the way for more accurate use of Carrington rotation-specific coronal models.

  5. Hybrid hierarchical bio-based materials: Development and characterization through experimentation and computational simulations

    Science.gov (United States)

    Haq, Mahmoodul

    Environmentally friendly bio-based composites with improved properties can be obtained by harnessing the synergy offered by hybrid constituents such as multiscale (nano- and micro-scale) reinforcement in bio-based resins composed of blends of synthetic and natural resins. Bio-based composites have recently gained much attention due to their low cost, environmental appeal and their potential to compete with synthetic composites. The advantage of multiscale reinforcement is that it offers synergy at various length scales, and when combined with bio-based resins provide stiffness-toughness balance, improved thermal and barrier properties, and increased environmental appeal to the resulting composites. Moreover, these hybrid materials are tailorable in performance and in environmental impact. While the use of different concepts of multiscale reinforcement has been studied for synthetic composites, the study of mukiphase/multiscale reinforcements for developing new types of sustainable materials is limited. The research summarized in this dissertation focused on development of multiscale reinforced bio-based composites and the effort to understand and exploit the synergy of its constituents through experimental characterization and computational simulations. Bio-based composites consisting of petroleum-based resin (unsaturated polyester), natural or bio-resin (epoxidized soybean and linseed oils), natural fibers (industrial hemp), and nanosilicate (nanoclay) inclusions were developed. The work followed the "materials by Mahmoodul Haq design" philosophy by incorporating an integrated experimental and computational approach to strategically explore the design possibilities and limits. Experiments demonstrated that the drawbacks of bio-resin addition, which lowers stiffness, strength and increases permeability, can be counter-balanced through nanoclay reinforcement. Bio-resin addition yields benefits in impact strength and ductility. Conversely, nanoclay enhances stiffness

  6. Hardware-Based Simulation of a Fuel Cell Turbine Hybrid Response to Imposed Fuel Cell Load Transients

    Energy Technology Data Exchange (ETDEWEB)

    Smith, T.P. (Georgia Inst. of Technology); Tucker, D.A.; Haynes, C.L. (Georgia Inst. of Technology); Liese, E.A.; Wepfer, W.J. (Georgia Inst. of Technology)

    2006-11-01

    Electrical load transients imposed on the cell stack of a solid oxide fuel cell/gas turbine hybrid power system are studied using the Hybrid Performance (HyPer) project. The hardware simulation facility is located at the U.S. Department of Energy, National Energy Technology Laboratory (NETL). A computational fuel cell model capable of operating in real time is integrated with operating gas turbine hardware. The thermal output of a modeled 350 kW solid oxide fuel cell stack is replicated in the facility by a natural gas fired burner in a direct fired hybrid configuration. Pressure vessels are used to represent a fuel cell stack's cathode flow and post combustion volume and flow impedance. This hardware is used to simulate the fuel cell stack and is incorporated with a modified turbine, compressor, and 120 kW generator on a single shaft. For this study, a simulation was started with a simulated current demand of 307 A on the fuel cell at approximately 0.75 V and an actual 45 kW electrical load on the gas turbine. An open loop response, allowing the turbine rotational speed to respond to thermal transients, was successfully evaluated for a 5% current reduction on the fuel cell followed by a 5% current increase. The impact of the fuel cell load change on system process variables is presented. The test results demonstrate the capabilities of the hardware-in-the-loop simulation approach in evaluating hybrid fuel cell turbine dynamics and performance.

  7. Working as simulated patient has effects on real patient life – Preliminary insights from a qualitative study

    Directory of Open Access Journals (Sweden)

    Simmenroth-Nayda, Anne

    2016-05-01

    Full Text Available Background: Persons who simulate patients during medical education understand the routines and the underlying script of medical consultations better. We aimed to explore how simulated patients (SPs integrated this new understanding into their daily life, how this work affected their private life as patients, and what we can learn from these changes for concepts of empowerment.Design, setting, and participants: A qualitative interview study. All SPs of Göttingen medical school who had been working longer than three semesters (n=14 were invited and agreed to take part in an open interview about their daily experience with real doctors. Documentary method was used to identify the main issues. Several cases were chosen according to maximum contrast and analysed by in-depth analysis to provide vivid examples of how simulations may affect the real life of the SPs as patients.Results: Our analysis revealed three main changes in the behaviour of SPs as real patients. They were more attentive, had a better understanding of the circumstances under which doctors work, and acted more self-confidently. From the selected cases it became apparent that working as a SP may lead to a constant and significant decrease of fear of hospitals and medical procedures or, in other cases, may enable the SPs to develop new abilities for giving feedback, questioning procedures, and explanations for real doctors.Conclusion: working as a simulated patient seems to be well-suited to understand own progression of diseases, to increase self-responsibility and to a confident attitude as patient.

  8. Mapping of coma anisotropies to plasma structures of weak comets: a 3-D hybrid simulation study

    Directory of Open Access Journals (Sweden)

    N. Gortsas

    2009-04-01

    Full Text Available The effects of coma anisotropies on the plasma environment of comets have been studied by means of a 3-D hybrid model which treats electrons as a massless, charge-neutralizing fluid, whereas ion dynamics are covered by a kinetic approach. From Earth-based observations as well as from in-situ spacecraft measurements the shape of the coma of many comets is ascertained to be anisotropic. However, most plasma simulation studies deploy a spherically symmetric activity pattern. In this paper anisotropy is studied by considering three different coma shape models. The first model is derived from the Haser model and is characterised by spherically symmetry. This reference model is then compared with two different neutral gas shape models: the dayside restricted model with no nightside activity and a cone shaped model with opening angle of π/2. In all models the integrated surface activity is kept constant. The simulations have been done for the Rosetta target comet 67P/Churyumov-Gerasimenko for two heliocentric distances, 1.30 AU and 3.25 AU. It is found that shock formation processes are modified as a result of increasing spatial confinement. Characteristic plasma structures of comets such as the bow shock, magnetic barrier region and the ion composition boundary exhibit a shift towards the sun. In addition, the cone shaped model leads to a strong increase of the mass-loaded region which in turn leads to a smooth deceleration of the solar wind flow and an increasing degree of mixture between the solar wind and cometary ion species. This creates an additional transport channel of the magnetic field from the magnetic barrier region away which in turn leads to a broadening of this region. In addition, it leads to an ion composition boundary which is only gradually developed.

  9. A new hybrid-Lagrangian numerical scheme for gyrokinetic simulation of tokamak edge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ku, S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Hager, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Chang, C. S. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Kwon, J. M. [National Fusion Research Institute, Republic of Korea; Parker, S. E. [University of Colorado Boulder, USA

    2016-06-01

    In order to enable kinetic simulation of non-thermal edge plasmas at a reduced computational cost, a new hybrid-Lagrangian δf scheme has been developed that utilizes the phase space grid in addition to the usual marker particles, taking advantage of the computational strengths from both sides. The new scheme splits the particle distribution function of a kinetic equation into two parts. Marker particles contain the fast space-time varying, δf, part of the distribution function and the coarse-grained phase-space grid contains the slow space-time varying part. The coarse-grained phase-space grid reduces the memory-requirement and the computing cost, while the marker particles provide scalable computing ability for the fine-grained physics. Weights of the marker particles are determined by a direct weight evolution equation instead of the differential form weight evolution equations that the conventional delta-f schemes use. The particle weight can be slowly transferred to the phase space grid, thereby reducing the growth of the particle weights. The non-Lagrangian part of the kinetic equation – e.g., collision operation, ionization, charge exchange, heat-source, radiative cooling, and others – can be operated directly on the phase space grid. Deviation of the particle distribution function on the velocity grid from a Maxwellian distribution function – driven by ionization, charge exchange and wall loss – is allowed to be arbitrarily large. The numerical scheme is implemented in the gyrokinetic particle code XGC1, which specializes in simulating the tokamak edge plasma that crosses the magnetic separatrix and is in contact with the material wall.

  10. Hybrid simulations of solenoidal radio-frequency inductively coupled hydrogen discharges at low pressures

    Science.gov (United States)

    Yang, Wei; Li, Hong; Gao, Fei; Wang, You-Nian

    2016-12-01

    In this article, we have described a radio-frequency (RF) inductively coupled H2 plasma using a hybrid computational model, incorporating the Maxwell equations and the linear part of the electron Boltzmann equation into global model equations. This report focuses on the effects of RF frequency, gas pressure, and coil current on the spatial profiles of the induced electric field and plasma absorption power density. The plasma parameters, i.e., plasma density, electron temperature, density of negative ion, electronegativity, densities of neutral species, and dissociation degree of H2, as a function of absorption power, are evaluated at different gas pressures. The simulation results show that the utilization efficiency of the RF source characterized by the coupling efficiency of the RF electric field and power to the plasma can be significantly improved at the low RF frequency, gas pressure, and coil current, due to a low plasma density in these cases. The densities of vibrational states of H2 first rapidly increase with increasing absorption power and then tend to saturate. This is because the rapidly increased dissociation degree of H2 with increasing absorption power somewhat suppresses the increase of the vibrational states of H2, thus inhibiting the increase of the H-. The effects of absorption power on the utilization efficiency of the RF source and the production of the vibrational states of H2 should be considered when setting a value of the coil current. To validate the model simulations, the calculated electron density and temperature are compared with experimental measurements, and a reasonable agreement is achieved.

  11. A new hybrid-Lagrangian numerical scheme for gyrokinetic simulation of tokamak edge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ku, S., E-mail: sku@pppl.gov [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Hager, R.; Chang, C.S. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543 (United States); Kwon, J.M. [National Fusion Research Institute (Korea, Republic of); Parker, S.E. [University of Colorado Boulder (United States)

    2016-06-15

    In order to enable kinetic simulation of non-thermal edge plasmas at a reduced computational cost, a new hybrid-Lagrangian δf scheme has been developed that utilizes the phase space grid in addition to the usual marker particles, taking advantage of the computational strengths from both sides. The new scheme splits the particle distribution function of a kinetic equation into two parts. Marker particles contain the fast space-time varying, δf, part of the distribution function and the coarse-grained phase-space grid contains the slow space-time varying part. The coarse-grained phase-space grid reduces the memory-requirement and the computing cost, while the marker particles provide scalable computing ability for the fine-grained physics. Weights of the marker particles are determined by a direct weight evolution equation instead of the differential form weight evolution equations that the conventional delta-f schemes use. The particle weight can be slowly transferred to the phase space grid, thereby reducing the growth of the particle weights. The non-Lagrangian part of the kinetic equation – e.g., collision operation, ionization, charge exchange, heat-source, radiative cooling, and others – can be operated directly on the phase space grid. Deviation of the particle distribution function on the velocity grid from a Maxwellian distribution function – driven by ionization, charge exchange and wall loss – is allowed to be arbitrarily large. The numerical scheme is implemented in the gyrokinetic particle code XGC1, which specializes in simulating the tokamak edge plasma that crosses the magnetic separatrix and is in contact with the material wall.

  12. A new hybrid-Lagrangian numerical scheme for gyrokinetic simulation of tokamak edge plasma

    Science.gov (United States)

    Ku, S.; Hager, R.; Chang, C. S.; Kwon, J. M.; Parker, S. E.

    2016-06-01

    In order to enable kinetic simulation of non-thermal edge plasmas at a reduced computational cost, a new hybrid-Lagrangian δf scheme has been developed that utilizes the phase space grid in addition to the usual marker particles, taking advantage of the computational strengths from both sides. The new scheme splits the particle distribution function of a kinetic equation into two parts. Marker particles contain the fast space-time varying, δf, part of the distribution function and the coarse-grained phase-space grid contains the slow space-time varying part. The coarse-grained phase-space grid reduces the memory-requirement and the computing cost, while the marker particles provide scalable computing ability for the fine-grained physics. Weights of the marker particles are determined by a direct weight evolution equation instead of the differential form weight evolution equations that the conventional delta-f schemes use. The particle weight can be slowly transferred to the phase space grid, thereby reducing the growth of the particle weights. The non-Lagrangian part of the kinetic equation - e.g., collision operation, ionization, charge exchange, heat-source, radiative cooling, and others - can be operated directly on the phase space grid. Deviation of the particle distribution function on the velocity grid from a Maxwellian distribution function - driven by ionization, charge exchange and wall loss - is allowed to be arbitrarily large. The numerical scheme is implemented in the gyrokinetic particle code XGC1, which specializes in simulating the tokamak edge plasma that crosses the magnetic separatrix and is in contact with the material wall.

  13. Subproton-scale Cascades in Solar Wind Turbulence: Driven Hybrid-kinetic Simulations

    Science.gov (United States)

    Cerri, S. S.; Califano, F.; Jenko, F.; Told, D.; Rincon, F.

    2016-05-01

    A long-lasting debate in space plasma physics concerns the nature of subproton-scale fluctuations in solar wind (SW) turbulence. Over the past decade, a series of theoretical and observational studies were presented in favor of either kinetic Alfvén wave (KAW) or whistler turbulence. Here, we investigate numerically the nature of the subproton-scale turbulent cascade for typical SW parameters by means of unprecedented high-resolution simulations of forced hybrid-kinetic turbulence in two real-space and three velocity-space dimensions. Our analysis suggests that small-scale turbulence in this model is dominated by KAWs at β ≳ 1 and by magnetosonic/whistler fluctuations at lower β. The spectral properties of the turbulence appear to be in good agreement with theoretical predictions. A tentative interpretation of this result in terms of relative changes in the damping rates of the different waves is also presented. Overall, the results raise interesting new questions about the properties and variability of subproton-scale turbulence in the SW, including its possible dependence on the plasma β, and call for detailed and extensive parametric explorations of driven kinetic turbulence in three dimensions.

  14. Subproton-scale cascades in solar wind turbulence: driven hybrid-kinetic simulations

    CERN Document Server

    Cerri, S S; Jenko, F; Told, D; Rincon, F

    2016-01-01

    A long-lasting debate in space plasma physics concerns the nature of subproton-scale fluctuations in solar wind (SW) turbulence. Over the past decade, a series of theoretical and observational studies were presented in favor of either kinetic Alfv\\'en wave (KAW) or whistler turbulence. Here, we investigate numerically the nature of the subproton-scale turbulent cascade for typical SW parameters by means of unprecedented high-resolution simulations of forced hybrid-kinetic turbulence in two real-space and three velocity-space dimensions. Our analysis suggests that small-scale turbulence in this model is dominated by KAWs at $\\beta\\gtrsim1$ and by magnetosonic/whistler fluctuations at lower $\\beta$. The spectral properties of the turbulence appear to be in good agreement with theoretical predictions. A tentative interpretation of this result in terms of relative changes in the damping rates of the different waves is also presented. Overall, the results raise interesting new questions about the properties and va...

  15. GPU accelerated Hybrid Tree Algorithm for Collision-less N-body Simulations

    CERN Document Server

    Watanabe, Tsuyoshi

    2014-01-01

    We propose a hybrid tree algorithm for reducing calculation and communication cost of collision-less N-body simulations. The concept of our algorithm is that we split interaction force into two parts: hard-force from neighbor particles and soft-force from distant particles, and applying different time integration for the forces. For hard-force calculation, we can efficiently reduce the calculation and communication cost of the parallel tree code because we only need data of neighbor particles for this part. We implement the algorithm on GPU clusters to accelerate force calculation for both hard and soft force. As the result of implementing the algorithm on GPU clusters, we were able to reduce the communication cost and the total execution time to 40% and 80% of that of a normal tree algorithm, respectively. In addition, the reduction factor relative the normal tree algorithm is smaller for large number of processes, and we expect that the execution time can be ultimately reduced down to about 70% of the norma...

  16. Coupled electric fields in photorefractive driven liquid crystal hybrid cells - theory and numerical simulation

    Science.gov (United States)

    Moszczyński, P.; Walczak, A.; Marciniak, P.

    2016-12-01

    In cyclic articles previously published we described and analysed self-organized light fibres inside a liquid crystalline (LC) cell contained photosensitive polymer (PP) layer. Such asymmetric LC cell we call a hybrid LC cell. Light fibre arises along a laser beam path directed in plane of an LC cell. It means that a laser beam is parallel to photosensitive layer. We observed the asymmetric LC cell response on an external driving field polarization. Observation has been done for an AC field first. It is the reason we decided to carry out a detailed research for a DC driving field to obtain an LC cell response step by step. The properly prepared LC cell has been built with an isolating layer and garbage ions deletion. We proved by means of a physical model, as well as a numerical simulation that LC asymmetric response strongly depends on junction barriers between PP and LC layers. New parametric model for a junction barrier on PP/LC boundary has been proposed. Such model is very useful because of lack of proper conductivity and charge carriers of band structure data on LC material.

  17. Terahertz spectra of biotin based on first principle, molecular mechanical, and hybrid simulations.

    Science.gov (United States)

    Bykhovski, Alexei; Woolard, Dwight

    2013-07-01

    Terahertz (THz) absorption of biotin was simulated using the first principle and the density functional theory (DFT) both in the harmonic approximation and with corrections for the anharmonicity. Anharmonicity corrections were calculated using two different approaches. First, the perturbation theory-based first principle calculations were performed to include third- and fourth-order anharmonicity corrections in atomic displacements to harmonic vibrational states. Second, the atom-centered density matrix propagation molecular dynamics model that provides a good energy conservation was used to calculate the atomic trajectories, velocities, and a dipole moment time history of biotin at low and room temperatures. Predicted low-THz lines agree well with the experimental spectra. The influence of the polyethylene (PE) matrix embedment on the THz spectra of biotin at the nanoscale was studied using the developed hybrid DFT/molecular mechanical approach. While PE is almost transparent at THz frequencies, additional low-THz lines are predicted in the biotin/PE system, which reflects a dynamic interaction between biotin and a surrounding PE cavity.

  18. Theory and hybrid simulations of the radial evolution of the solar wind turbulence

    Science.gov (United States)

    Comisel, Horia; Narita, Yasuhito; Motschmann, Uwe

    2016-04-01

    Solar wind turbulence in the inner heliosphere is believed to evolve in the radial direction away from the Sun driven by various nonlinear processes. When a perturbative treatment is applicable, plasma fluctuations evolve along the dispersion relations while the frequencies deviate from the normal-mode frequency by exciting non-normal modes or sideband waves. Direct numerical simulations of magnetized plasma at the scale of ion gyro-radius or smaller using the hybrid code AIKEF show smooth transitions and evolutions into nonlinear stage with sideband wave excitations. The evolution profile of linear and nonlinear modes as well as the intrinsic nature of wave vector anisotropy can be unambiguously classified according to the values of ion plasma beta. By using a mapping based on a one-dimensional solar wind expansion model, the resulting ion kinetic scale turbulence is related to the solar distance from the Sun. We find that the relevant normal modes such as ion cyclotron and Bernstein mode will occur first at radial distance of about 0.2-0.3 AU, i.e., near the Mercury orbit. Furthermore, a radial dependence of the wave-vector anisotropy is obtained. The predominance of the filament structures highlights the strong impact of Alfvénic waves.

  19. Three-dimensional Hybrid Continuum-Atomistic Simulations for Multiscale Hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Wijesinghe, S; Hornung, R; Garcia, A; Hadjiconstantinou, N

    2004-04-15

    We present an adaptive mesh and algorithmic refinement (AMAR) scheme for modeling multi-scale hydrodynamics. The AMAR approach extends standard conservative adaptive mesh refinement (AMR) algorithms by providing a robust flux-based method for coupling an atomistic fluid representation to a continuum model. The atomistic model is applied locally in regions where the continuum description is invalid or inaccurate, such as near strong flow gradients and at fluid interfaces, or when the continuum grid is refined to the molecular scale. The need for such ''hybrid'' methods arises from the fact that hydrodynamics modeled by continuum representations are often under-resolved or inaccurate while solutions generated using molecular resolution globally are not feasible. In the implementation described herein, Direct Simulation Monte Carlo (DSMC) provides an atomistic description of the flow and the compressible two-fluid Euler equations serve as our continuum-scale model. The AMR methodology provides local grid refinement while the algorithm refinement feature allows the transition to DSMC where needed. The continuum and atomistic representations are coupled by matching fluxes at the continuum-atomistic interfaces and by proper averaging and interpolation of data between scales. Our AMAR application code is implemented in C++ and is built upon the SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) framework developed at Lawrence Livermore National Laboratory. SAMRAI provides the parallel adaptive gridding algorithm and enables the coupling between the continuum and atomistic methods.

  20. Hybrid Potential Simulation of the Acylation of Enterococcus faecium l,d-Transpeptidase by Carbapenems.

    Science.gov (United States)

    Bhattacharjee, Nicholus; Field, Martin J; Simorre, Jean-Pierre; Arthur, Michel; Bougault, Catherine M

    2016-06-01

    The l,d-transpeptidases, Ldts, catalyze peptidoglycan cross-linking in β-lactam-resistant mutant strains of several bacteria, including Enterococcus faecium and Mycobacterium tuberculosis. Although unrelated to the essential d,d-transpeptidases, which are inactivated by the β-lactam antibiotics, they are nevertheless inhibited by the carbapenem antibiotics, making them potentially useful targets in the treatment of some important diseases. In this work, we have investigated the acylation mechanism of the Ldt from E. faecium by the carbapenem, ertapenem, using computational techniques. We have employed molecular dynamics simulations in conjunction with QC/MM hybrid potential calculations to map out possible reaction paths. We have focused on determining the following: (i) the protonation state of the nucleophilic cysteine of the enzyme when it attacks; (ii) whether nucleophilic attack and β-lactam ring-opening are concerted or stepwise, the latter occurring via an oxyanion intermediate; and (iii) the identities of the proton acceptors at the beginning and end of the reaction. Overall, we note that there is considerable plasticity in the mechanisms, owing to the significant flexibility of the enzyme, but find that the preferred pathways are ones in which nucleophilic attack of cysteine thiolate is concerted with β-lactam ring-opening.

  1. Proton and Helium Injection Into First Order Fermi Acceleration at Shocks: Hybrid Simulation and Analysis

    Science.gov (United States)

    Dudnikova, Galina; Malkov, Mikhail; Sagdeev, Roald; Liseykina, Tatjana; Hanusch, Adrian

    2016-10-01

    Elemental composition of galactic cosmic rays (CR) probably holds the key to their origin. Most likely, they are accelerated at collisionless shocks in supernova remnants, but the acceleration mechanism is not entirely understood. One complicated problem is ``injection'', a process whereby the shock selects a tiny fraction of particles to keep on crossing its front and gain more energy. Comparing the injection rates of particles with different mass to charge ratio is a powerful tool for studying this process. Recent advances in measurements of CR He/p ratio have provided particularly important new clues. We performed a series of hybrid simulations and analyzed a joint injection of protons and Helium, in conjunction with upstream waves they generate. The emphasis of this work is on the bootstrap aspects of injection manifested in particle confinement to the shock and, therefore, their continuing acceleration by the self-driven waves. The waves are initially generated by He and protons in separate spectral regions, and their interaction plays a crucial role in particle acceleration. The work is ongoing and new results will be reported along with their analysis and comparison with the latest data from the AMS-02 space-based spectrometer. Work supported Grant RFBR 16-01-00209, NASA ATP-program under Award NNX14AH36G, and by the US Department of Energy under Award No. DE-FG02-04ER54738.

  2. Particle-in-cell simulation study of a lower-hybrid shock

    Science.gov (United States)

    Dieckmann, M. E.; Sarri, G.; Doria, D.; Ynnerman, A.; Borghesi, M.

    2016-06-01

    The expansion of a magnetized high-pressure plasma into a low-pressure ambient medium is examined with particle-in-cell simulations. The magnetic field points perpendicular to the plasma's expansion direction and binary collisions between particles are absent. The expanding plasma steepens into a quasi-electrostatic shock that is sustained by the lower-hybrid (LH) wave. The ambipolar electric field points in the expansion direction and it induces together with the background magnetic field a fast E cross B drift of electrons. The drifting electrons modify the background magnetic field, resulting in its pile-up by the LH shock. The magnetic pressure gradient force accelerates the ambient ions ahead of the LH shock, reducing the relative velocity between the ambient plasma and the LH shock to about the phase speed of the shocked LH wave, transforming the LH shock into a nonlinear LH wave. The oscillations of the electrostatic potential have a larger amplitude and wavelength in the magnetized plasma than in an unmagnetized one with otherwise identical conditions. The energy loss to the drifting electrons leads to a noticeable slowdown of the LH shock compared to that in an unmagnetized plasma.

  3. Numerical simulation of active track tensioning system for autonomous hybrid vehicle

    Science.gov (United States)

    Mȩżyk, Arkadiusz; Czapla, Tomasz; Klein, Wojciech; Mura, Gabriel

    2017-05-01

    One of the most important components of a high speed tracked vehicle is an efficient suspension system. The vehicle should be able to operate both in rough terrain for performance of engineering tasks as well as on the road with high speed. This is especially important for an autonomous platform that operates either with or without human supervision, so that the vibration level can rise compared to a manned vehicle. In this case critical electronic and electric parts must be protected to ensure the reliability of the vehicle. The paper presents a dynamic parameters determination methodology of suspension system for an autonomous high speed tracked platform with total weight of about 5 tonnes and hybrid propulsion system. Common among tracked vehicles suspension solutions and cost-efficient, the torsion-bar system was chosen. One of the most important issues was determining optimal track tensioning - in this case an active hydraulic system was applied. The selection of system parameters was performed with using numerical model based on multi-body dynamic approach. The results of numerical analysis were used to define parameters of active tensioning control system setup. LMS Virtual.Lab Motion was used for multi-body dynamics numerical calculation and Matlab/SIMULINK for control system simulation.

  4. Semi-active tuned liquid column damper implementation with real-time hybrid simulations

    Science.gov (United States)

    Riascos, Carlos; Marulanda Casas, Johannio; Thomson, Peter

    2016-04-01

    Real-time hybrid simulation (RTHS) is a modern cyber-physical technique used for the experimental evaluation of complex systems, that treats the system components with predictable behavior as a numerical substructure and the components that are difficult to model as an experimental substructure. Therefore it is an attractive method for evaluation of the response of civil structures under earthquake, wind and anthropic loads. In this paper, the response of three-story shear frame controlled by a tuned liquid column damper (TLCD) and subject to base excitation is considered. Both passive and semi-active control strategies were implemented and are compared. While the passive TLCD achieved a reduction of 50% in the acceleration response of the main structure in comparison with the structure without control, the semi-active TLCD achieved a reduction of 70%, and was robust to variations in the dynamic properties of the main structure. In addition, a RTHS was implemented with the main structure modeled as a linear, time-invariant (LTI) system through a state space representation and the TLCD, with both control strategies, was evaluated on a shake table that reproduced the displacement of the virtual structure. Current assessment measures for RTHS were used to quantify the performance with parameters such as generalized amplitude, equivalent time delay between the target and measured displacement of the shake table, and energy error using the measured force, and prove that the RTHS described in this paper is an accurate method for the experimental evaluation of structural control systems.

  5. Particle-in-cell simulation study of a lower-hybrid shock

    CERN Document Server

    Dieckmann, Mark Eric; Doria, Domenico; Ynnerman, Anders; Borghesi, Marco

    2016-01-01

    The expansion of a magnetized high-pressure plasma into a low-pressure ambient medium is examined with particle-in-cell (PIC) simulations. The magnetic field points perpendicularly to the plasma's expansion direction and binary collisions between particles are absent. The expanding plasma steepens into a quasi-electrostatic shock that is sustained by the lower-hybrid (LH) wave. The ambipolar electric field points in the expansion direction and it induces together with the background magnetic field a fast E cross B drift of electrons. The drifting electrons modify the background magnetic field, resulting in its pile-up by the LH shock. The magnetic pressure gradient force accelerates the ambient ions ahead of the LH shock, reducing the relative velocity between the ambient plasma and the LH shock to about the phase speed of the shocked LH wave, transforming the LH shock into a nonlinear LH wave. The oscillations of the electrostatic potential have a larger amplitude and wavelength in the magnetized plasma than...

  6. Learning health ‘safety’ within non-technical skills interprofessional simulation education: a qualitative study

    Science.gov (United States)

    Gordon, Morris; Fell, Christopher W. R.; Box, Helen; Farrell, Michael; Stewart, Alison

    2017-01-01

    ABSTRACT Background: Healthcare increasingly recognises and focusses on the phenomena of ‘safe practice’ and ‘patient safety.’ Success with non-technical skills (NTS) training in other industries has led to widespread transposition to healthcare education, with communication and teamwork skills central to NTS frameworks. Objective: This study set out to identify how the context of interprofessional simulation learning influences NTS acquisition and development of ‘safety’ amongst learners. Methods: Participants receiving a non-technical skills (NTS) safety focussed training package were invited to take part in a focus group interview which set out to explore communication, teamwork, and the phenomenon of safety in the context of the learning experiences they had within the training programme. The analysis was aligned with a constructivist paradigm and took an interactive methodological approach. The analysis proceeded through three stages, consisting of open, axial, and selective coding, with constant comparisons taking place throughout each phase. Each stage provided categories that could be used to explore the themes of the data. Additionally, to ensure thematic saturation, transcripts of observed simulated learning encounters were then analysed. Results: Six themes were established at the axial coding level, i.e., analytical skills, personal behaviours, communication, teamwork, context, and pedagogy. Underlying these themes, two principal concepts emerged, namely: intergroup contact anxiety – as both a result of and determinant of communication – and teamwork, both of which must be considered in relation to context. These concepts have subsequently been used to propose a framework for NTS learning. Conclusions: This study highlights the role of intergroup contact anxiety and teamwork as factors in NTS behaviour and its dissipation through interprofessional simulation learning. Therefore, this should be a key consideration in NTS education. Future

  7. Effect of backbone chemistry on hybridization thermodynamics of oligonucleic acids: a coarse-grained molecular dynamics simulation study.

    Science.gov (United States)

    Ghobadi, Ahmadreza F; Jayaraman, Arthi

    2016-02-28

    In this paper we study how varying oligonucleic acid backbone chemistry affects the hybridization/melting thermodynamics of oligonucleic acids. We first describe the coarse-grained (CG) model with tunable parameters that we developed to enable the study of both naturally occurring oligonucleic acids, such as DNA, and their chemically-modified analogues, such as peptide nucleic acids (PNAs) and locked nucleic acids (LNAs). The DNA melting curves obtained using such a CG model and molecular dynamics simulations in an implicit solvent and with explicit ions match with the melting curves obtained using the empirical nearest-neighbor models. We use these CG simulations to then elucidate the effect of backbone flexibility, charge, and nucleobase spacing along the backbone on the melting curves, potential energy and conformational entropy change upon hybridization and base-pair hydrogen bond residence time. We find that increasing backbone flexibility decreases duplex thermal stability and melting temperature mainly due to increased conformational entropy loss upon hybridization. Removing charges from the backbone enhances duplex thermal stability due to the elimination of electrostatic repulsion and as a result a larger energetic gain upon hybridization. Lastly, increasing nucleobase spacing decreases duplex thermal stability due to decreasing stacking interactions that are important for duplex stability.

  8. Qualitative analysis and quantitative simulation on Yin-Huang water salinization mechanism in Bei-Da-Gang Reservoir

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wen-yu; WANG Qi-shan; WU Li-bo; ZHANG Bin; WANG Xiao-qin

    2005-01-01

    Yellow River water transfer for Tianjin is important in solving the water shortage in Tianjin, which facilitate economic development and social progress for many years. Fresh water drawn from Yellow River(i. e., Yin-Huang water) becomes saltier and saltier when being stored in the Bei-Da-Gang reservoir. We qualitatively analyze the water salinization mechanism based on mass transfer theory. The main factors are salinity transfer of saline soil, evaporation concentrating, and the agitation of wind. A simulative experimental pond and an evaporation pond were built beside the Bei-Da-Gang reservoir to quantitatively investigate the water salinization based on water and solute balance in the simulative pond. 80% of increased [Cl- ] is due to the salinity transfer of the saline soil and the other 20% is due to evaporation concentrating, so the former is the most important factor. We found that the salinization of Yin-Huang water can be described with a zero-dimension linear model.

  9. Modeling, Simulation Design and Control of Hybrid-Electric Vehicle Drives

    Energy Technology Data Exchange (ETDEWEB)

    Giorgio Rizzoni

    2005-09-30

    Ohio State University (OSU) is uniquely poised to establish such a center, with interdisciplinary emphasis on modeling, simulation, design and control of hybrid-electric drives for a number of reasons, some of which are: (1) The OSU Center for Automotive Research (CAR) already provides an infrastructure for interdisciplinary automotive research and graduate education; the facilities available at OSU-CAR in the area of vehicle and powertrain research are among the best in the country. CAR facilities include 31,000 sq. feet of space, multiple chassis and engine dynamometers, an anechoic chamber, and a high bay area. (2) OSU has in excess of 10 graduate level courses related to automotive systems. A graduate level sequence has already been initiated with GM. In addition, an Automotive Systems Engineering (ASE) program cosponsored by the mechanical and electrical engineering programs, had been formulated earlier at OSU, independent of the GATE program proposal. The main objective of the ASE is to provide multidisciplinary graduate education and training in the field of automotive systems to Masters level students. This graduate program can be easily adapted to fulfill the spirit of the GATE Center of Excellence. (3) A program in Mechatronic Systems Engineering has been in place at OSU since 1994; this program has a strong emphasis on automotive system integration issues, and has emphasized hybrid-electric vehicles as one of its application areas. (4) OSU researchers affiliated with CAR have been directly involved in the development and study of: HEV modeling and simulation; electric drives; transmission design and control; combustion engines; and energy storage systems. These activities have been conducted in collaboration with government and automotive industry sponsors; further, the same researchers have been actively involved in continuing education programs in these areas with the automotive industry. The proposed effort will include: (1) The development of a

  10. Numerical simulation of particulate flows using a hybrid of finite difference and boundary integral methods.

    Science.gov (United States)

    Bhattacharya, Amitabh; Kesarkar, Tejas

    2016-10-01

    A combination of finite difference (FD) and boundary integral (BI) methods is used to formulate an efficient solver for simulating unsteady Stokes flow around particles. The two-dimensional (2D) unsteady Stokes equation is being solved on a Cartesian grid using a second order FD method, while the 2D steady Stokes equation is being solved near the particle using BI method. The two methods are coupled within the viscous boundary layer, a few FD grid cells away from the particle, where solutions from both FD and BI methods are valid. We demonstrate that this hybrid method can be used to accurately solve for the flow around particles with irregular shapes, even though radius of curvature of the particle surface is not resolved by the FD grid. For dilute particle concentrations, we construct a virtual envelope around each particle and solve the BI problem for the flow field located between the envelope and the particle. The BI solver provides velocity boundary condition to the FD solver at "boundary" nodes located on the FD grid, adjacent to the particles, while the FD solver provides the velocity boundary condition to the BI solver at points located on the envelope. The coupling between FD method and BI method is implicit at every time step. This method allows us to formulate an O(N) scheme for dilute suspensions, where N is the number of particles. For semidilute suspensions, where particles may cluster, an envelope formation method has been formulated and implemented, which enables solving the BI problem for each individual particle cluster, allowing efficient simulation of hydrodynamic interaction between particles even when they are in close proximity. The method has been validated against analytical results for flow around a periodic array of cylinders and for Jeffrey orbit of a moving ellipse in shear flow. Simulation of multiple force-free irregular shaped particles in the presence of shear in a 2D slit flow has been conducted to demonstrate the robustness of

  11. Hybrid photovoltaic/thermal (PV/T) solar systems simulation with Simulink/Matlab

    Energy Technology Data Exchange (ETDEWEB)

    da Silva, R.M.; Fernandes, J.L.M. [Department of Mechanical Engineering, Instituto Superior Tecnico, Lisbon (Portugal)

    2010-12-15

    The purpose of this work consists in thermodynamic modeling of hybrid photovoltaic-thermal (PV/T) solar systems, pursuing a modular strategy approach provided by Simulink/Matlab. PV/T solar systems are a recently emerging solar technology that allows for the simultaneous conversion of solar energy into both electricity and heat. This type of technology present some interesting advantages over the conventional ''side-by-side'' thermal and PV solar systems, such as higher combined electrical/thermal energy outputs per unit area, and a more uniform and aesthetical pleasant roof area. Despite the fact that early research on PV/T systems can be traced back to the seventies, only recently it has gained a renewed impetus. In this work, parametric studies and annual transient simulations of PV/T systems are undertaken in Simulink/Matlab. The obtained results show an average annual solar fraction of 67%, and a global overall efficiency of 24% (i.e. 15% thermal and 9% electrical), for a typical four-person single-family residence in Lisbon, with p-Si cells, and a collector area of 6 m{sup 2}. A sensitivity analysis performed on the PV/T collector suggests that the most important variable that should be addressed to improve thermal performance is the photovoltaic (PV) module emittance. Based on those results, some additional improvements are proposed, such as the use of vacuum, or a noble gas at low-pressure, to allow for the removal of PV cells encapsulation without air oxidation and degradation, and thus reducing the PV module emittance. Preliminary results show that this option allows for an 8% increase on optical thermal efficiency, and a substantial reduction of thermal losses, suggesting the possibility of working at higher fluid temperatures. The higher working temperatures negative effect in electrical efficiency was negligible, due to compensation by improved optical properties. The simulation results are compared with experimental data obtained

  12. Seismic performance evaluation of an MR elastomer-based smart base isolation system using real-time hybrid simulation

    Science.gov (United States)

    Eem, S. H.; Jung, H. J.; Koo, J. H.

    2013-05-01

    Recently, magneto-rheological (MR) elastomer-based base isolation systems have been actively studied as alternative smart base isolation systems because MR elastomers are capable of adjusting their modulus or stiffness depending on the magnitude of the applied magnetic field. By taking advantage of the MR elastomers’ stiffness-tuning ability, MR elastomer-based smart base isolation systems strive to alleviate limitations of existing smart base isolation systems as well as passive-type base isolators. Until now, research on MR elastomer-based base isolation systems primarily focused on characterization, design, and numerical evaluations of MR elastomer-based isolators, as well as experimental tests with simple structure models. However, their applicability to large civil structures has not been properly studied yet because it is quite challenging to numerically emulate the complex behavior of MR elastomer-based isolators and to conduct experiments with large-size structures. To address these difficulties, this study employs the real-time hybrid simulation technique, which combines physical testing and computational modeling. The primary goal of the current hybrid simulation study is to evaluate seismic performances of an MR elastomer-based smart base isolation system, particularly its adaptability to distinctly different seismic excitations. In the hybrid simulation, a single-story building structure (non-physical, computational model) is coupled with a physical testing setup for a smart base isolation system with associated components (such as laminated MR elastomers and electromagnets) installed on a shaking table. A series of hybrid simulations is carried out under two seismic excitations having different dominant frequencies. The results show that the proposed smart base isolation system outperforms the passive base isolation system in reducing the responses of the structure for the excitations considered in this study.

  13. Numerical methodologies for investigation of moderate-velocity flow using a hybrid computational fluid dynamics - molecular dynamics simulation approach

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Soon Heum [Linkoeping University, Linkoeping (Sweden); Kim, Na Yong; Nikitopoulos, Dimitris E.; Moldovan, Dorel [Louisiana State University, Baton Rouge (United States); Jha, Shantenu [Rutgers University, Piscataway (United States)

    2014-01-15

    Numerical approaches are presented to minimize the statistical errors inherently present due to finite sampling and the presence of thermal fluctuations in the molecular region of a hybrid computational fluid dynamics (CFD) - molecular dynamics (MD) flow solution. Near the fluid-solid interface the hybrid CFD-MD simulation approach provides a more accurate solution, especially in the presence of significant molecular-level phenomena, than the traditional continuum-based simulation techniques. It also involves less computational cost than the pure particle-based MD. Despite these advantages the hybrid CFD-MD methodology has been applied mostly in flow studies at high velocities, mainly because of the higher statistical errors associated with low velocities. As an alternative to the costly increase of the size of the MD region to decrease statistical errors, we investigate a few numerical approaches that reduce sampling noise of the solution at moderate-velocities. These methods are based on sampling of multiple simulation replicas and linear regression of multiple spatial/temporal samples. We discuss the advantages and disadvantages of each technique in the perspective of solution accuracy and computational cost.

  14. Crash simulation of hybrid structures considering the stress and strain rate dependent material behavior of thermoplastic materials

    Science.gov (United States)

    Hopmann, Ch.; Schöngart, M.; Weber, M.; Klein, J.

    2015-05-01

    Thermoplastic materials are more and more used as a light weight replacement for metal, especially in the automotive industry. Since these materials do not provide the mechanical properties, which are required to manufacture supporting elements like an auto body or a cross bearer, plastics are combined with metals in so called hybrid structures. Normally, the plastics components are joined to the metal structures using different technologies like welding or screwing. Very often, the hybrid structures are made of flat metal parts, which are stiffened by a reinforcement structure made of thermoplastic materials. The loads on these structures are very often impulsive, for example in the crash situation of an automobile. Due to the large stiffness variation of metal and thermoplastic materials, complex states of stress and very high local strain rates occur in the contact zone under impact conditions. Since the mechanical behavior of thermoplastic materials is highly dependent on these types of load, the crash failure of metal plastic hybrid parts is very complex. The problem is that the normally used strain rate dependent elastic/plastic material models are not capable to simulate the mechanical behavior of thermoplastic materials depended on the state of stress. As part of a research project, a method to simulate the mechanical behavior of hybrid structures under impact conditions is developed at the IKV. For this purpose, a specimen for the measurement of mechanical properties dependet on the state of stress and a method for the strain rate depended characterization of thermoplastic materials were developed. In the second step impact testing is performed. A hybrid structure made from a metal sheet and a reinforcement structure of a Polybutylenterephthalat Polycarbonate blend is tested under impact conditions. The measured stress and strain rate depended material data are used to simulate the mechanical behavior of the hybrid structure under highly dynamic load with

  15. First Lunar Wake Passage of ARTEMIS: Discrimination of Wake Effects and Solar Wind Fluctuations by 3D Hybrid Simulations

    Science.gov (United States)

    Wiehle, S.; Plaschke, F.; Motschmann, U.; Glassmeier, K. H.; Auster, H. U.; Angelopoulos, V.; Mueller, J.; Kriegel, H.; Georgescu, E.; Halekas, J.; Sibeck, D. G.; McFadden, J. P.

    2011-01-01

    The spacecraft P1 of the new ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun) mission passed the lunar wake for the first time on February 13, 2010. We present magnetic field and plasma data of this event and results of 3D hybrid simulations. As the solar wind magnetic field was highly dynamic during the passage, a simulation with stationary solar wind input cannot distinguish whether distortions were caused by these solar wind variations or by the lunar wake; therefore, a dynamic real-time simulation of the flyby has been performed. The input values of this simulation are taken from NASA OMNI data and adapted to the P1 data, resulting in a good agreement between simulation and measurements. Combined with the stationary simulation showing non-transient lunar wake structures, a separation of solar wind and wake effects is achieved. An anisotropy in the magnitude of the plasma bulk flow velocity caused by a non-vanishing magnetic field component parallel to the solar wind flow and perturbations created by counterstreaming ions in the lunar wake are observed in data and simulations. The simulations help to interpret the data granting us the opportunity to examine the entire lunar plasma environment and, thus, extending the possibilities of measurements alone: A comparison of a simulation cross section to theoretical predictions of MHD wave propagation shows that all three basic MHD modes are present in the lunar wake and that their expansion governs the lunar wake refilling process.

  16. Interest of general tools of functional simulation in the idea of `mecatronic` groups: an application to energy management of hybrid vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Esteve, D.; Jammes, B.; Vinassa, J.M.; Marpinard, J.C.

    1994-04-01

    This report is a first approach of the simulation to validate the structure of the traction chain of a hybrid vehicle. This first step relies on the use of existing models in libraries of simulation programs. The next steps are going to consist in improving these models, in writing others one more performing and to test this simulation about energy management. (N.C.).

  17. Simulation of Potential Production and Optimum Population Quantitative Indices for the Second Hybrid Rice

    Institute of Scientific and Technical Information of China (English)

    YAN Li-jiao; YAO Zhong; ZHENG Zhi-ming; LI Hua-bin

    2006-01-01

    The article established the HDRICE model by modifying the structure of the ORYZA1 model and revising its parameters by field experiments. The HDRICE model consists of the modules of morphological development of rice, daily dry matter accumulation and partitioning, daily CO2 assimilation of the canopy, leaf area, and tiller development. The model preferably simulated the dynamic rice development because of the thorough integration of the effects of temperature and light on the rates of rice development, photosynthesis, respiration, and. other ecophysiological processes. In addition, this model has attainable grain yield in the test experiment that showed the potential yield of cultivar Xieyou 46 ranged from 11 to 13 tons ha-1. Besides, the model was used to optimize the combinations of the transplanting date, seedling age and density for cultivar Xieyou 46 at Jinhua area, and the population quantitative indices to attain the potential yield such as maximum stems, effective panicles, filled grain number/leaf area, and so on. The result showed that the combination of transplanting date on July 25, seedling age of 35 days and base seedling density of 1.33 × 106ha-1 is the optimum combination for the second hybrid rice production in Jinhua County, China. And the maximum stems, the effective panicles, the filled grain per panicle, the peak of optimum LAI, LAI in later filling stage, and the filled grain number/leaf were 6.03 × 106 ha, 3.99 × 106 ha,119.2, 8.59, 5-6, and 0.64, respectively.

  18. Hall effect control of magnetotail dawn-dusk asymmetry: A three-dimensional global hybrid simulation

    Science.gov (United States)

    Lu, San; Lin, Y.; Angelopoulos, V.; Artemyev, A. V.; Pritchett, P. L.; Lu, Quanming; Wang, X. Y.

    2016-12-01

    Magnetotail reconnection and related phenomena (e.g., flux ropes, dipolarizing flux bundles, flow bursts, and particle injections) occur more frequently on the duskside than on the dawnside. Because this asymmetry can directly result in dawn-dusk asymmetric space weather effects, uncovering its physical origin is important for better understanding, modeling, and prediction of the space weather phenomena. However, the cause of this pervasive asymmetry is unclear. Using three-dimensional global hybrid simulations, we demonstrate that the Hall physics in the magnetotail current sheet is responsible for the asymmetry. The current sheet thins progressively under enhanced global convection; when its thickness reaches ion kinetic scales, some ions are decoupled from the magnetized electrons (the Hall effect). The resultant Hall electric field Ez is directed toward the neutral plane. The Hall effect is stronger (grows faster) on the duskside; i.e., more ions become unmagnetized there and do not comove with the magnetized dawnward Ez × Bx drifting electrons, thus creating a larger additional cross-tail current intensity jy (in addition to the diamagnetic current) on the duskside, compared to the dawnside. The stronger Hall effect strength on the duskside is controlled by the higher ion temperature, thinner current sheet, and smaller normal magnetic field Bz there. These asymmetric current sheet properties are in turn controlled by two competing processes that correspond to the Hall effect: (1) the dawnward E × B drift of the magnetic flux and magnetized ions and electrons and (2) the transient motion of the unmagnetized ions which do not execute E × B drift.

  19. Numerical simulation of a hybrid CSP/Biomass 5 MWel power plant

    Science.gov (United States)

    Soares, João; Oliveira, Armando

    2017-06-01

    The fundamental benefit of using renewable energy systems is undeniable since they rely on a source that will not run out. Nevertheless, they strongly depend on meteorological conditions (solar, wind, etc.), leading to uncertainty of instantaneous energy supply and consequently to grid connection issues. An interesting concept is renewable hybridisation. This consists in the strategic combination of different renewable sources in the power generation portfolio by taking advantage of each technology. Hybridisation of concentrating solar power with biomass denotes a powerful way of assuring system stability and reliability. The main advantage is dispatchability through the whole extent of the operating range. Regarding concentrating solar power heat transfer fluid, direct steam generation is one of the most interesting concepts. Nevertheless, it presents itself technical challenges that are mostly related to the two-phase fluid flow in horizontal pipes, as well as the design of an energy storage system. Also, the use of reheat within the turbine is usually indirectly addressed, hindering system efficiency. These challenges can be addressed through hybridisation with biomass. In this paper, a hybrid renewable electricity generation system is presented. The system relies on a combination of solar and biomass sources to drive a 5 MWel steam turbine. System performance is analysed through numerical simulation using Ebsilon professional software. The use of direct reheat in the turbine is addressed. Results show that hybridisation results in an enhancement of system dispatchability and generation stability. Furthermore, hybridisation enhanced the annual solar field and power block efficiencies, and thus the system annual efficiency (from 7.6% to 20%). The use of direct reheat eliminates steam wetness in the last turbine stage and also improves system efficiency.

  20. Fate of bulk and trace organics during a simulated aquifer recharge and recovery (ARR)-ozone hybrid process.

    Science.gov (United States)

    Yoon, Min K; Drewes, Jörg E; Amy, Gary L

    2013-11-01

    The attenuation of bulk organic matter and trace organic contaminants (TOrCs) was evaluated for various aquifer recharge and recovery (ARR)-ozone (O3) hybrid treatment process combinations using soil-batch reactor and bench-scale ozonation experiments as a proof of concept prior to pilot and/or field studies. In water reclamation and especially potable reuse, refractory bulk organic matter and TOrCs are of potential health concern in recycled waters. In this study, the role of biotransformation of bulk organic matter and TOrCs was investigated considering different simulated treatment combinations, including soil passage (ARR) alone, ARR after ozonation (O3-ARR), and ARR prior to ozonation (ARR-O3). During oxic (aerobic) ARR simulations, soluble microbial-like substances (e.g., higher molecular weight polysaccharides and proteins) were easily removed while (lower molecular weight) humic substances and aromatic organic matter were not efficiently removed. During ARR-ozone treatment simulations, removals of bulk organic matter and TOrCs were rapid and effective compared to ARR alone. A higher reduction of effluent-derived organic matter, including aromatic organic matter and humic substances, was observed in the ARR-O3 hybrid followed by the O3-ARR hybrid. An enhanced attenuation of recalcitrant TOrCs was observed while increasing the ozone dose slightly (O3: DOC=1). TOrC removal efficiency also increased during the post-ozone treatment combination (i.e., ARR-O3). In addition, the carcinogenic wastewater disinfection byproduct N-nitrosodimethylamine (NDMA) was eliminated below the method reporting limit (<5 ng L(-1)) both during ARR treatment alone and the ARR-ozone hybrid.

  1. Numerical simulation and validation of SI-CAI hybrid combustion in a CAI/HCCI gasoline engine

    Science.gov (United States)

    Wang, Xinyan; Xie, Hui; Xie, Liyan; Zhang, Lianfang; Li, Le; Chen, Tao; Zhao, Hua

    2013-02-01

    SI-CAI hybrid combustion, also known as spark-assisted compression ignition (SACI), is a promising concept to extend the operating range of CAI (Controlled Auto-Ignition) and achieve the smooth transition between spark ignition (SI) and CAI in the gasoline engine. In this study, a SI-CAI hybrid combustion model (HCM) has been constructed on the basis of the 3-Zones Extended Coherent Flame Model (ECFM3Z). An ignition model is included to initiate the ECFM3Z calculation and induce the flame propagation. In order to precisely depict the subsequent auto-ignition process of the unburned fuel and air mixture independently after the initiation of flame propagation, the tabulated chemistry concept is adopted to describe the auto-ignition chemistry. The methodology for extracting tabulated parameters from the chemical kinetics calculations is developed so that both cool flame reactions and main auto-ignition combustion can be well captured under a wider range of thermodynamic conditions. The SI-CAI hybrid combustion model (HCM) is then applied in the three-dimensional computational fluid dynamics (3-D CFD) engine simulation. The simulation results are compared with the experimental data obtained from a single cylinder VVA engine. The detailed analysis of the simulations demonstrates that the SI-CAI hybrid combustion process is characterised with the early flame propagation and subsequent multi-site auto-ignition around the main flame front, which is consistent with the optical results reported by other researchers. Besides, the systematic study of the in-cylinder condition reveals the influence mechanism of the early flame propagation on the subsequent auto-ignition.

  2. Fate of bulk and trace organics during a simulated aquifer recharge and recovery (ARR)-ozone hybrid process

    KAUST Repository

    Yoon, Min

    2013-11-01

    The attenuation of bulk organic matter and trace organic contaminants (TOrCs) was evaluated for various aquifer recharge and recovery (ARR)-ozone (O3) hybrid treatment process combinations using soil-batch reactor and bench-scale ozonation experiments as a proof of concept prior to pilot and/or field studies. In water reclamation and especially potable reuse, refractory bulk organic matter and TOrCs are of potential health concern in recycled waters. In this study, the role of biotransformation of bulk organic matter and TOrCs was investigated considering different simulated treatment combinations, including soil passage (ARR) alone, ARR after ozonation (O3-ARR), and ARR prior to ozonation (ARR-O3). During oxic (aerobic) ARR simulations, soluble microbial-like substances (e.g., higher molecular weight polysaccharides and proteins) were easily removed while (lower molecular weight) humic substances and aromatic organic matter were not efficiently removed. During ARR-ozone treatment simulations, removals of bulk organic matter and TOrCs were rapid and effective compared to ARR alone. A higher reduction of effluent-derived organic matter, including aromatic organic matter and humic substances, was observed in the ARR-O3 hybrid followed by the O3-ARR hybrid. An enhanced attenuation of recalcitrant TOrCs was observed while increasing the ozone dose slightly (O3: DOC=1). TOrC removal efficiency also increased during the post-ozone treatment combination (i.e., ARR-O3). In addition, the carcinogenic wastewater disinfection byproduct N-nitrosodimethylamine (NDMA) was eliminated below the method reporting limit (<5ngL-1) both during ARR treatment alone and the ARR-ozone hybrid. © 2013 Elsevier Ltd.

  3. Dynamic Modeling and Simulation of a Thermoelectric-Solar Hybrid Energy System Using an Inverse Dynamic Analysis Input Shaper

    Directory of Open Access Journals (Sweden)

    A. M. Yusop

    2014-01-01

    Full Text Available This study presents the behavioral model of thermal temperature and power generation of a thermoelectric-solar hybrid energy system exposed to dynamic transient sources. In the development of thermoelectric-solar hybrid energy system, studies have focused on the regulation of both systems separately. In practice, a separate control system affects hardware pricing. In this study, an inverse dynamic analysis shaping technique based on exponential function is applied to a solar array (SA to stabilize output voltage before this technique is combined with a thermoelectric module (TEM. This method can be used to estimate the maximum power point of the hybrid system by initially shaping the input voltage of SA. The behavior of the overall system can be estimated by controlling the behavior of SA, such that SA can follow the output voltage of TEM as the time constant of TEM is greater than that of SA. Moreover, by employing a continuous and differentiable function, the acquired output behavior of the hybrid system can be attained. Data showing the model is obtained from current experiments with predicted values of temperature, internal resistance, and current attributes of TEM. The simulation results show that the proposed input shaper can be used to trigger the output voltage of SA to follow the TEM behavior under transient conditions.

  4. (I Can't Get No) Saturation: A simulation and guidelines for sample sizes in qualitative research.

    Science.gov (United States)

    van Rijnsoever, Frank J

    2017-01-01

    I explore the sample size in qualitative research that is required to reach theoretical saturation. I conceptualize a population as consisting of sub-populations that contain different types of information sources that hold a number of codes. Theoretical saturation is reached after all the codes in the population have been observed once in the sample. I delineate three different scenarios to sample information sources: "random chance," which is based on probability sampling, "minimal information," which yields at least one new code per sampling step, and "maximum information," which yields the largest number of new codes per sampling step. Next, I use simulations to assess the minimum sample size for each scenario for systematically varying hypothetical populations. I show that theoretical saturation is more dependent on the mean probability of observing codes than on the number of codes in a population. Moreover, the minimal and maximal information scenarios are significantly more efficient than random chance, but yield fewer repetitions per code to validate the findings. I formulate guidelines for purposive sampling and recommend that researchers follow a minimum information scenario.

  5. Fuel Economy and Performance of Mild Hybrids with Ultracapacitors: Simulations and Vehicle Test Results (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Gonder, J.; Pesaran, A.; Lustbader, J.; Tataria, H.

    2009-06-01

    NREL worked with GM and demonstrated equivalent performance in the Saturn Vue Belt Alternator Starter (BAS) hybrid vehicle whether running with its stock batteries or a retrofit ultracapacitor system.

  6. Three-dimensional finite element simulation of intermingled-fiber hybrid composite behavior

    Science.gov (United States)

    Mital, Subodh K.; Chamis, Christos C.

    1992-01-01

    Three-dimensional finite element methods and the intraply hybrid micromechanics equations are used to predict composite properties for a unidirectional graphite-epoxy primary composite with S-glass fibers used as hybridizing fibers. The micromechanics equations are embedded in a computer code ICAN (Integrated Composites Analyzer). The three-dimensional finite element model consists of three-by-three unit cell array, with a total fiber volume ratio of 0.54. There is a good agreement between the composite properties and microstresses obtained from both methods. The results indicate that the finite element methods and micromechanics equations can be used to obtain the properties of intermingled hybrid composites needed for analysis/design of hybrid composite structures.

  7. Application of Hybrid Real-Time Power System Simulator for Designing and Researching of Relay Protection and Automation

    Science.gov (United States)

    Borovikov, Yu S.; Sulaymanov, A. O.; Andreev, M. V.

    2015-10-01

    Development, research and operation of smart grids (SG) with active-adaptive networks (AAS) are actual tasks for today. Planned integration of high-speed FACTS devices greatly complicates complex dynamic properties of power systems. As a result the operating conditions of equipment of power systems are significantly changing. Such situation creates the new actual problem of development and research of relay protection and automation (RPA) which will be able to adequately operate in the SGs and adapt to its regimes. Effectiveness of solution of the problem depends on using tools - different simulators of electric power systems. Analysis of the most famous and widely exploited simulators led to the conclusion about the impossibility of using them for solution of the mentioned problem. In Tomsk Polytechnic University developed the prototype of hybrid multiprocessor software and hardware system - Hybrid Real-Time Power System Simulator (HRTSim). Because of its unique features this simulator can be used for solution of mentioned tasks. This article introduces the concept of development and research of relay protection and automation with usage of HRTSim.

  8. Hybrid method for fast Monte Carlo simulation of diffuse reflectance from a multilayered tissue model with tumor-like heterogeneities.

    Science.gov (United States)

    Zhu, Caigang; Liu, Quan

    2012-01-01

    We present a hybrid method that combines a multilayered scaling method and a perturbation method to speed up the Monte Carlo simulation of diffuse reflectance from a multilayered tissue model with finite-size tumor-like heterogeneities. The proposed method consists of two steps. In the first step, a set of photon trajectory information generated from a baseline Monte Carlo simulation is utilized to scale the exit weight and exit distance of survival photons for the multilayered tissue model. In the second step, another set of photon trajectory information, including the locations of all collision events from the baseline simulation and the scaling result obtained from the first step, is employed by the perturbation Monte Carlo method to estimate diffuse reflectance from the multilayered tissue model with tumor-like heterogeneities. Our method is demonstrated to shorten simulation time by several orders of magnitude. Moreover, this hybrid method works for a larger range of probe configurations and tumor models than the scaling method or the perturbation method alone.

  9. Hybrid neural network model for simulating sorbitol synthesis by glucose-fructose oxidoreductase in Zymomonas mobilis CP4

    Directory of Open Access Journals (Sweden)

    Bravo S.

    2004-01-01

    Full Text Available A hybrid neural network model for simulating the process of enzymatic reduction of fructose to sorbitol process catalyzed by glucose-fructose oxidoreductase in Zymomonas mobilis CP4 is presented. Data used to derive and validate the model was obtained from experiments carried out under different conditions of pH, temperature and concentrations of both substrates (glucose and fructose involved in the reaction. Sonicated and lyophilized cells were used as source of the enzyme. The optimal pH for sorbitol synthesis at 30º C is 6.5. For a value of pH of 6, the optimal temperature is 35º C. The neural network in the model computes the value of the kinetic relationship. The hybrid neural network model is able to simulate changes in the substrates and product concentrations during sorbitol synthesis under pH and temperature conditions ranging between 5 and 7.5 and 25 and 40º C, respectively. Under these conditions the rate of sorbitol synthesis shows important differences. Values computed using the hybrid neural network model have an average error of 1.7·10-3 mole.

  10. Optical Simulation and Experimental Verification of a Fresnel Solar Concentrator with a New Hybrid Second Optical Element

    Directory of Open Access Journals (Sweden)

    Guiqiang Li

    2016-01-01

    Full Text Available Fresnel solar concentrator is one of the most common solar concentrators in solar applications. For high Fresnel concentrating PV or PV/T systems, the second optical element (SOE is the key component for the high optical efficiency at a wider deflection angle, which is important for overcoming unavoidable errors from the tacking system, the Fresnel lens processing and installment technology, and so forth. In this paper, a new hybrid SOE was designed to match the Fresnel solar concentrator with the concentration ratio of 1090x. The ray-tracing technology was employed to indicate the optical properties. The simulation outcome showed that the Fresnel solar concentrator with the new hybrid SOE has a wider deflection angle scope with the high optical efficiency. Furthermore, the flux distribution with different deviation angles was also analyzed. In addition, the experiment of the Fresnel solar concentrator with the hybrid SOE under outdoor condition was carried out. The verifications from the electrical and thermal outputs were all made to analyze the optical efficiency comprehensively. The optical efficiency resulting from the experiment is found to be consistent with that from the simulation.

  11. Applying new hybrid method of analytical hierarchy process, Monte Carlo Simulation and PROMETHEE to prioritize and selecting appropriate target market

    Directory of Open Access Journals (Sweden)

    Amir Kariznoee

    2015-06-01

    Full Text Available Making decision to choose the appropriate target market is one of the key decisions in the success of firms, which has direct effect in the amount of their profits. The aim of this paper is to introduce and use of new hybrid method of AHP, Monte Carlo simulation and PROMETHEE to prioritize cities to establish retailers, considering different indices. The problem of this study is related to a factory, constructing premade pieces of buildings, that to introduce and distribute its new products is searching the new retailers in different cities. To prioritize cities, with the interview with experts and the studying of the previous works the indices have been determined and the hierarchy pattern has been made. Then using the hybrid method of AHP and Monte Carlo simulation the weights of the indices have been determined and then using PROMETHEE method the best city has been chosen and the other ones have been prioritized. From the benefits of the new introduced hybrid method with respect to other ways of selecting target markets is decreasing the risk and increasing the power of decision making.

  12. STRUCTURE DEVELOPMENT AND SIMULATION OF PLUG-IN HYBRID ELECTRIC VEHICLE

    OpenAIRE

    A. A. Marozka; Yu. N. Petrenko

    2013-01-01

    Electric-drive vehicles (EDVs) have gained attention, especially in the context of growing concerns about global warming and energy security aspects associated with road transport. The main characteristic of EDVs is that the torque is supplied to the wheels by an electric motor that is powered either solely by a battery or in combination with an internal combustion engine (ICE). This covers hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), and plug-in hybrid electric vehicles...

  13. Qualitative Simulation on Dynamic Process of Organizational Culture%组织文化演变的定性模拟分析

    Institute of Scientific and Technical Information of China (English)

    吴婷; 胡斌

    2008-01-01

    The dynamic process of organizational culture in the complex condition was simulated by using qualitative simulation. Based on the research of Denison, twenty model variables were classified into three levels. The definition of organizational culture, the research methods and the concrete simulation process were discussed. By using qualitative reasoning, the qualitative simulation model of organizational culture was proposed, and its simulation results were drawn.%介绍了组织文化的研究现状,并提出使用定性模拟方法来模拟复杂环境下组织文化的演变.作者以定量研究派得出的结果作为模型建立的依据,根据denison的思想,用20个因素作为模型变量,并将其分为三个层次,并通过定性推理技术建立了组织丈化研究的定性模拟模型,最后提供了模拟结果.

  14. Monte Carlo simulations of biaxial structure in thin hybrid nematic film based upon spatially anisotropic pair potential

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhi-Dong; Chang Chun-Rui; Ma Dong-Lai

    2009-01-01

    Hybrid nematic films have been studied by Monte Carlo simulations using a lattice spin model,in which the pair potential is spatially anisotropic and dependent on elastic constants of liquid crystals.We confirm in the thin hybrid nematic film the existence of a biaxially nonbent structure and the structarc transition from the biaxial to the bent-director structure,which is similar to the result obtained using the Lebwohl-Lasher model.However,the step-like director's profile,characteristic for the biaxial structure,is spatially asymmetric in the film because the pair potential leads to K1≠K3.We estimate the upper cell thickness to be 69 spin layers,in which the biaxial structure can be found.

  15. Passive hybrid force-position control for tele-operation based on real-time simulation of a virtual mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Joly, L.; Andriot, C.

    1995-12-31

    Hybrid force-position control aims at controlling position and force in separate directions. It is particularly useful to perform certain robotic tasks. In tele-operation context, passivity is important because it ensures stability when the system interacts with any passive environment. In this paper, we propose an original approach to hybrid force-position control of a force reflecting tele-robot system. It is based on real-time simulation of a virtual mechanism corresponding to the task. the resulting control law is passive. Experiments on a 6 degrees of freedom tele-operation system consisting in following a bent pipe under several control modes validate the approach. (authors). 12 refs., 6 figs.

  16. Dynamic Modeling, Control and Simulation of a Wind and PV Hybrid System for Grid Connected Application Using MATLAB

    Directory of Open Access Journals (Sweden)

    D. Mahesh Naik

    2014-07-01

    Full Text Available This paper proposes a dynamic modeling and control strategy for a grid connected hybrid wind and photovoltaic (PV energy system inter-connected to electrical grid through power electronic interface. A gearless permanent magnet synchronous generator (PMSG is used to capture the maximum wind energy. The PV and wind systems are connected dc-side of the voltage source inverter through a boost converter individually and maintain a fixed dc output at dc link. A proper control scheme is required to operate power converters to match up the grid connection requirements. This study considered the performance of modeled hybrid system under different case scenarios. All simulation models are developed using MATLAB/Simulink.

  17. Modeling,Analysis and Simulation ofThree Phase Hybrid Power Filter forPower Quality Improvement

    Directory of Open Access Journals (Sweden)

    Prashanta Kumar Das

    2012-05-01

    Full Text Available A three-phase hybrid series power filter is constituted by a series active filter and a passive filter connected in parallel with the load. The control strategy is based on the “dual formulation of the electric power vectorial theory”. The proposed algorithm eliminates the current harmonics of supply. It also improves the power factor and harmonic compensation features of the associated passive filter even if there is a change in system parameters.A shunt hybrid power filter is constituted by a shunt active filter and a passive filter connected in parallel with the load, is proposed with same control strategy. Simulations have been carried out on the MATLAB-SIMULINK platform with different loads and with variation in the source impedance.

  18. Optimization of Electric Power Leveling Systems by a Novel Hybrid Algorithm with Simulated Evolution and Genetic Algorithms

    Science.gov (United States)

    Itoh, Jyunpei; Yamamoto, Masayoshi; Funabiki, Shigeyuki

    Electric power demand has an increasing tendency year by year. The fluctuation of the electric power causes further increase in the cost of the electric power facility and electricity charges. The development of the electric power-leveling systems (EPLS) using energy storage technology is desired to improve the electric power quality. The EPLS with a SMES is proposed as one of the countermeasures for the electric power quality improvement. However, the SMES is very expensive and it is difficult to decide the gains of the controller. It is essential in the practical use that the reduction of SMES capacity is realized. This paper proposes a new optimization method of the EPLS. The proposed algorithm is hybrid architecture with a combination of SimE (Simulated Evolution) and GA (Genetic Algorithms). The optimization of the EPLS can be achieved by the proposed hybrid algorithm compared to the SimE and the GA.

  19. Phase equilibria of molecular fluids via hybrid Monte Carlo Wang-Landau simulations: applications to benzene and n-alkanes.

    Science.gov (United States)

    Desgranges, Caroline; Delhommelle, Jerome

    2009-06-28

    In recent years, powerful and accurate methods, based on a Wang-Landau sampling, have been developed to determine phase equilibria. However, while these methods have been extensively applied to study the phase behavior of model fluids, they have yet to be applied to molecular systems. In this work, we show how, by combining hybrid Monte Carlo simulations in the isothermal-isobaric ensemble with the Wang-Landau sampling method, we determine the vapor-liquid equilibria of various molecular fluids. More specifically, we present results obtained on rigid molecules, such as benzene, as well as on flexible chains of n-alkanes. The reliability of the method introduced in this work is assessed by demonstrating that our results are in excellent agreement with the results obtained in previous work on simple fluids, using either transition matrix or conventional Monte Carlo simulations with a Wang-Landau sampling, and on molecular fluids, using histogram reweighting or Gibbs ensemble Monte Carlo simulations.

  20. Molecular dynamics simulation of joining process of Ag-Au nanowires and mechanical properties of the hybrid nanojoint

    Directory of Open Access Journals (Sweden)

    Su Ding

    2015-05-01

    Full Text Available The nanojoining process of Ag-Au hybrid nanowires at 800K was comprehensively studied by virtue of molecular dynamics (MD simulation. Three kinds of configurations including end-to-end, T-like and X-like were built in the simulation aiming to understand the nanojoining mechanism. The detailed dynamic evolution of atoms, crystal structure transformation and defects development during the nanojoining processes were performed. The results indicate that there are two stages in the nanojoining process of Ag-Au nanowires which are atom diffusion and new bonds formation. Temperature is a key parameter affecting both stages ascribed to the energy supply and the optimum temperature for Ag-Au nanojoint with diameter of 4.08 nm has been discussed. The mechanical properties of the nanojoint were examined with simulation of tensile test on the end-to-end joint. It was revealed that the nanojoint was strong enough to resist fracture at the joining area.

  1. Dynamic modelling of an adsorption storage tank using a hybrid approach combining computational fluid dynamics and process simulation

    Science.gov (United States)

    Mota, J.P.B.; Esteves, I.A.A.C.; Rostam-Abadi, M.

    2004-01-01

    A computational fluid dynamics (CFD) software package has been coupled with the dynamic process simulator of an adsorption storage tank for methane fuelled vehicles. The two solvers run as independent processes and handle non-overlapping portions of the computational domain. The codes exchange data on the boundary interface of the two domains to ensure continuity of the solution and of its gradient. A software interface was developed to dynamically suspend and activate each process as necessary, and be responsible for data exchange and process synchronization. This hybrid computational tool has been successfully employed to accurately simulate the discharge of a new tank design and evaluate its performance. The case study presented here shows that CFD and process simulation are highly complementary computational tools, and that there are clear benefits to be gained from a close integration of the two. ?? 2004 Elsevier Ltd. All rights reserved.

  2. Hybrid schemes based on quantum mechanics/molecular mechanics simulations goals to success, problems, and perspectives.

    Science.gov (United States)

    Ferrer, Silvia; Ruiz-Pernía, Javier; Martí, Sergio; Moliner, Vicent; Tuñón, Iñaki; Bertrán, Juan; Andrés, Juan

    2011-01-01

    active site can be optimized to improve the transition state analogues (TSA) and to enhance the catalytic activity, even improve the active site to favor a desired direction of some promiscuous enzymes. In this chapter, we give a brief introduction, the state of the art, and future prospects and implications of enzyme design. Current computational tools to assist experimentalists for the design and engineering of proteins with desired catalytic properties are described. The interplay between enzyme design, molecular simulations, and experiments will be presented to emphasize the interdisciplinary nature of this research field. This text highlights the recent advances and examples selected from our laboratory are shown, of how the applications of these tools are a first attempt to de novo design of protein active sites. Identification of neutral/advantageous/deleterious mutation platforms can be exploited to penetrate some of Nature's closely guarded secrets of chemical reactivity. In this chapter, we give a brief introduction, the state of the art, and future prospects and implications of enzyme design. The first part describes briefly how the molecular modeling is carried out. Then, we discuss the requirements of hybrid quantum mechanical/molecular mechanics molecular dynamics (QM/MM MD) simulations, analyzing what are the basis of these theoretical methodologies, how we can use them with a view to its application in the study of enzyme catalysis, and what are the best methodologies for assessing its catalytic potential. In the second part, we focus on some selected examples, taking as a common guide the chorismate to prephenate rearrangement, studying the corresponding molecular mechanism in vacuo, in solution and in an enzyme environment. In addition, examples involving catalytic antibodies (CAs) and promiscuous enzymes will be presented. Finally, a special emphasis is made to provide some hints about the logical evolution that can be anticipated in this research

  3. Monte Carlo simulation of simultaneous radiation detection in the hybrid tomography system ClearPET-XPAD3/CT

    Science.gov (United States)

    Dávila, H. Olaya; Sevilla, A. C.; Castro, H. F.; Martínez, S. A.

    2016-07-01

    Using the Geant4 based simulation framework SciFW1, a detailed simulation was performed for a detector array in the hybrid tomography prototype for small animals called ClearPET / XPAD, which was built in the Centre de Physique des Particules de Marseille. The detector system consists of an array of phoswich scintillation detectors: LSO (Lutetium Oxy-ortosilicate doped with cerium Lu2SiO5:Ce) and LuYAP (Lutetium Ortoaluminate of Yttrium doped with cerium Lu0.7Y0.3AlO3:Ce) for Positron Emission Tomography (PET) and hybrid pixel detector XPAD for Computed Tomography (CT). Simultaneous acquisition of deposited energy and the corresponding time - position for each recorded event were analyzed, independently, for both detectors. interference between detection modules for PET and CT. Information about amount of radiation reaching each phoswich crystal and XPAD detector using a phantom in order to study the effectiveness by radiation attenuation and influence the positioning of the radioactive source 22Na was obtained. The simulation proposed will improve distribution of detectors rings and interference values will be taken into account in the new versions of detectors.

  4. 3-D hybrid LES-RANS model for simulation of open-channel T-diversion flows

    Institute of Scientific and Technical Information of China (English)

    Jie ZHOU; Cheng ZENG

    2009-01-01

    The study of flow diversions in open channels plays an important practical role in the design and management of open-channel networks for irrigation or drainage.To accurately predict the mean flow and turbulence characteristics of open-channel dividing flows,a hybrid LES-RANS model,which combines the large eddy simulation (LES) model with the Reynolds-averaged Navier-Stokes (RANS) model,is proposed in the present study.The unsteady RANS model was used to simulate the upstream and downstream regions of a main channel,as well as the downstream region of a branch channel.The LES model was used to simulate the channel diversion region,where turbulent flow characteristics ate complicated.Isotropic velocity fluctuations were added at the inflow interface of the LES region to trigger the generation of resolved turbulence.A method based on the virtual body force is proposed to impose Reynolds-averaged velocity fields near the outlet of the LES region in order to take downstream flow effects computed by the RANS model into account and dissipate the excessive turbulent fluctuations.This hybrid approach saves computational effort and makes it easier to properly specify inlet and outlet boundary conditions.Comparison between computational results and experimental data indicates that this relatively new modeling approach can accurately predict open-channel T-diversion flows.

  5. A HYBRID MODEL FOR SIMULATING VELOCITY FIELD OF A RIVER WITH COMPLEX GEOMETRY PLUNGED BY MULTIPLE JETS

    Institute of Scientific and Technical Information of China (English)

    LI Lian-xia; LIAO Hua-sheng; LI Tian-xiang

    2006-01-01

    A hybrid model that combines both physical and numerical models was employed to simulate the velocity field in a river area in complex geometry with multiple plunging jets. The simulation was based on experiments concerning energy dissipation and scour prevention at the Xiluodu Hydropower Station on the Yangtze River. The calculated results indicate that the complex geometry of the river area has a significant influence on the velocity field, especially on the circulation flow pattern at upstream and downstream of the plunging area and on the asymmetric characteristics of the spiral flow near both banks. The scour characteristics of the downstream river bed caused by the multiple jets were also predicted and analyzed according to the characteristics of the calculated velocity field. The good agreement between the simulated and experimental results indicates that the hybrid model can be used to effectively solve complicated 3-D problems with complex geometric and inlet conditions. Such problems may not easily be solved by using either a physical or a numerical model alone, and therefore the method presented in this article is considered to be a practical and effective way of dealing with this kind of problems.

  6. SiSeRHMap v1.0: a simulator for mapped seismic response using a hybrid model

    Science.gov (United States)

    Grelle, Gerardo; Bonito, Laura; Lampasi, Alessandro; Revellino, Paola; Guerriero, Luigi; Sappa, Giuseppe; Guadagno, Francesco Maria

    2016-04-01

    The SiSeRHMap (simulator for mapped seismic response using a hybrid model) is a computerized methodology capable of elaborating prediction maps of seismic response in terms of acceleration spectra. It was realized on the basis of a hybrid model which combines different approaches and models in a new and non-conventional way. These approaches and models are organized in a code architecture composed of five interdependent modules. A GIS (geographic information system) cubic model (GCM), which is a layered computational structure based on the concept of lithodynamic units and zones, aims at reproducing a parameterized layered subsoil model. A meta-modelling process confers a hybrid nature to the methodology. In this process, the one-dimensional (1-D) linear equivalent analysis produces acceleration response spectra for a specified number of site profiles using one or more input motions. The shear wave velocity-thickness profiles, defined as trainers, are randomly selected in each zone. Subsequently, a numerical adaptive simulation model (Emul-spectra) is optimized on the above trainer acceleration response spectra by means of a dedicated evolutionary algorithm (EA) and the Levenberg-Marquardt algorithm (LMA) as the final optimizer. In the final step, the GCM maps executor module produces a serial map set of a stratigraphic seismic response at different periods, grid solving the calibrated Emul-spectra model. In addition, the spectra topographic amplification is also computed by means of a 3-D validated numerical prediction model. This model is built to match the results of the numerical simulations related to isolate reliefs using GIS morphometric data. In this way, different sets of seismic response maps are developed on which maps of design acceleration response spectra are also defined by means of an enveloping technique.

  7. Simulation and optimum design of hybrid solar-wind and solar-wind-diesel power generation systems

    Science.gov (United States)

    Zhou, Wei

    optimal sizing method was developed to find the system optimum configuration and settings that can achieve the custom-required Renewable Energy Fraction (fRE) of the system with minimum Annualized Cost of System (ACS). Du to the need for optimum design of the hybrid systems, an analysis of local weather conditions (solar radiation and wind speed) was carried out for the potential installation site, and mathematical simulation of the hybrid systems' components was also carried out including PV array, wind turbine and battery bank. By statistically analyzing the long-term hourly solar and wind speed data, Hong Kong area is found to have favorite solar and wind power resources compared with other areas, which validates the practical applications in Hong Kong and Guangdong area. Simulation of PV array performance includes three main parts: modeling of the maximum power output of the PV array, calculation of the total solar radiation on any tilted surface with any orientations, and PV module temperature predictions. Five parameters are introduced to account for the complex dependence of PV array performance upon solar radiation intensities and PV module temperatures. The developed simulation model was validated by using the field-measured data from one existing building-integrated photovoltaic system (BIPV) in Hong Kong, and good simulation performance of the model was achieved. Lead-acid batteries used in hybrid systems operate under very specific conditions, which often cause difficulties to predict when energy will be extracted from or supplied to the battery. In this thesis, the lead-acid battery performance is simulated by three different characteristics: battery state of charge (SOC), battery floating charge voltage and the expected battery lifetime. Good agreements were found between the predicted values and the field-measured data of a hybrid solar-wind project. At last, one 19.8kW hybrid solar-wind power generation project, designed by the optimal sizing method and

  8. Critical rotation of general-relativistic polytropic models simulating neutron stars: a post-Newtonian hybrid approximative scheme

    CERN Document Server

    Geroyannis, Vassilis S

    2014-01-01

    We develop a "hybrid approximative scheme" in the framework of the post-Newtonian approximation for computing general-relativistic polytropic models simulating neutron stars in critical rigid rotation. We treat the differential equations governing such a model as a "complex initial value problem", and we solve it by using the so-called "complex-plane strategy". We incorporate into the computations the complete solution for the relativistic effects, this issue representing a significant improvement with regard to the classical post-Newtonian approximation, as verified by extended comparisons of the numerical results.

  9. Control Strategies, Robustness Analysis, Digital Simulation and Practical Implementation for a Hybrid APF with a Resonant Ac-link

    Directory of Open Access Journals (Sweden)

    Chen Chen

    2010-12-01

    Full Text Available This paper proposes a novel hybrid active power filter (HAPF topology based onthe cascaded connection of the AC-side capacitor and the third-order LCL-filter, which hasthe advantage of the conventional hybrid filter and the LCL-filter in terms of reduced dclinkvoltage and better switching ripple attenuation. The robust deadbeat control law isderived for the current loop, with special emphasis on robustness analysis. The stabilityand robustness analysis under parameter variations are presented for the converter-sidecurrent tracking scheme and the grid-side current tracking scheme. It is found that thestability margins obtained from the converter-side current tracking control scheme aregenerally higher than those obtained from the grid-side current tracking scheme. However,the converter-side current tracking scheme is sensitive to the variation of the dampingresistance, and it would impose additional parameter uncertainty on the control system andcomplicate the problem. Hence the grid-side current tracking scheme is implemented. Thesimulation results obtained from Matlab/Simulink are presented for verification, where theinductance variation and grid disturbance scenarios are also taken into consideration. Theeffectiveness of the proposed hybrid APF is substantially confirmed by the simulation andexperimental results.

  10. Investigation of interphase effects in silica-polystyrene nanocomposites based on a hybrid molecular-dynamics-finite-element simulation framework

    Science.gov (United States)

    Pfaller, Sebastian; Possart, Gunnar; Steinmann, Paul; Rahimi, Mohammad; Müller-Plathe, Florian; Böhm, Michael C.

    2016-05-01

    A recently developed hybrid method is employed to study the mechanical behavior of silica-polystyrene nanocomposites (NCs) under uniaxial elongation. The hybrid method couples a particle domain to a continuum domain. The region of physical interest, i.e., the interphase around a nanoparticle (NP), is treated at molecular resolution, while the surrounding elastic continuum is handled with a finite-element approach. In the present paper we analyze the polymer behavior in the neighborhood of one or two nanoparticle(s) at molecular resolution. The coarse-grained hybrid method allows us to simulate a large polymer matrix region surrounding the nanoparticles. We consider NCs with dilute concentration of NPs embedded in an atactic polystyrene matrix formed by 300 chains with 200 monomer beads. The overall orientation of polymer segments relative to the deformation direction is determined in the neighborhood of the nanoparticle to investigate the polymer response to this perturbation. Calculations of strainlike quantities give insight into the deformation behavior of a system with two NPs and show that the applied strain and the nanoparticle distance have significant influence on the deformation behavior. Finally, we investigate to what extent a continuum-based description may account for the specific effects occurring in the interphase between the polymer matrix and the NPs.

  11. A New Optimum Frequency Controller of Hybrid Pumping System: Bond Graph Modeling-Simulation and Practice with ARDUINO Board

    Directory of Open Access Journals (Sweden)

    MEZGHANI Dhafer

    2017-01-01

    Full Text Available The strategy of rural development in Tunisia needs to include as one of its priorities: the control of water. In seeking solutions for the energy control dedicated to pumping, it seems interesting to know the benefits of a new technique based on the complementarities of two renewable energy sources such as solar and wind power. The climate’s dependence requires a complex modelling and more optimization methods for controlling of hybrid system. Moreover, in recent years, technological progression at hardware and software enables researchers to process these optimization problems using embedded platforms. For this paper, we apply the approach bond graph to model a complex system. Our hybrid pumping installation contains a photovoltaic generator, a wind source, converters and an induction motor-pump group. The numerical closed-loop simulation of the complete model in an appropriate environment allows us to generate an optimisation control whose the appropriate frequency depends on meteorological conditions (wind speed, insulation and temperature. The implementation of this control and the experimental measurements validate the optimum efficiency and verify operation reliability of our hybrid structure.

  12. Experimental evaluation of hybrid vehicle fuel economy and pollutant emissions over real-world simulation driving cycles

    Science.gov (United States)

    Fontaras, Georgios; Pistikopoulos, Panayotis; Samaras, Zissis

    2008-06-01

    The reduction of transport-generated CO2 emissions is currently a problem of global interest. Hybrid electric vehicles (HEVs) are considered as one promising technological solution for limiting transport-generated greenhouse gas emissions. Currently, the number of HEVs in the market remains limited, but this picture will change in the years to come as HEVs are expected to pave the way for cleaner technologies in transport. In this paper, results are presented regarding fuel economy and pollutant emissions measurements of two hybrid electric production vehicles. The measurements were conducted on a Prius II and a Honda Civic IMA using both the European legislated driving cycle (New European Driving Cycle, NEDC) and real-world simulation driving cycles (Artemis). In addition to the emissions measurements, other vehicle-operating parameters were studied in an effort to better quantify the maximum CO2 reduction potential. Data from real-world operation of a Prius II vehicle were also used in the evaluation. Results indicate that in most cases both vehicles present improved energy efficiency and pollutant emissions compared to conventional cars. The fuel economy benefit of the two HEVs peaked under urban driving conditions where reductions of 60% and 40% were observed, respectively. Over higher speeds the difference in fuel economy was lower, reaching that of conventional diesel at 95 km h-1. The effect of ambient temperature on fuel consumption was also quantified. It is concluded that urban operation benefits the most of hybrid technology, leading to important fuel savings and urban air quality improvement.

  13. Fabrication of a TiO2@porphyrin nanofiber hybrid material: a highly efficient photocatalyst under simulated sunlight irradiation

    Science.gov (United States)

    La, Duong Duc; Rananaware, Anushri; Phuong Nguyen Thi, Hoai; Jones, Lathe; Bhosale, Sheshanath V.

    2017-03-01

    The solar spectrum consists of 8% UV radiation, while 45% of solar energy is from visible light. It is therefore desirable to fabricate a hybrid material which is able to harvest energy from a wide range of photons from the sun for applications such as solar cells, photovoltaics, and photocatalysis. In this study we report on the fabrication of a TiO2@porphyrin hybrid material by surfactant-assisted co-assembly of monomeric porphyrin molecules with TiO2 nanoparticles. The obtained TiO2@porphyrin composite shows excellent integration of TiO2 particles with diameters of 15–30 nm into aggregated porphyrin nanofibers, which have a width of 70–90 nm and are several µm long. SEM, XPS, XRD, FTIR, UV–Vis and fluorescence spectroscopy were employed to characterize the TiO2@TCPP hybrid material. This material exhibits efficient photocatalytic performance under simulated sunlight, due to synergistic photocatalytic activities of the porphyrin aggregates in visible light and TiO2 particles in the UV region. A plausible mechanism for photocatalytic degradation is also proposed and discussed.

  14. A Hybrid Approach to Combine Physically Based and Data-Driven Models in Simulating Sediment Transportation

    NARCIS (Netherlands)

    Sewagudde, S.

    2008-01-01

    The objective of this study is to develop a methodology for hybrid modelling of sedimentation in a coastal basin or large shallow lake where physically based and data driven approaches are combined. This research was broken down into three blocks. The first block explores the possibility of approxim

  15. Molecular dynamics simulation of the formation of sp3 hybridized bonds in hydrogenated diamondlike carbon deposition processes.

    Science.gov (United States)

    Murakami, Yasuo; Horiguchi, Seishi; Hamaguchi, Satoshi

    2010-04-01

    The formation process of sp3 hybridized carbon networks (i.e., diamondlike structures) in hydrogenated diamondlike carbon (DLC) films has been studied with the use of molecular-dynamics simulations. The processes simulated in this study are injections of hydrocarbon (CH3 and CH) beams into amorphous carbon (a-C) substrates. It has been shown that diamondlike sp3 structures are formed predominantly at a subsurface level when the beam energy is relatively high, as in the "subplantation" process for hydrogen-free DLC deposition. However, for hydrogenated DLC deposition, the presence of abundant hydrogen at subsurface levels, together with thermal spikes caused by energetic ion injections, substantially enhances the formation of carbon-to-carbon sp3 bonds. Therefore, the sp3 bond formation process for hydrogenated DLC films essentially differs from that for hydrogen-free DLC films.

  16. Formation and transport of entropy structures in the magnetotail simulated with a 3-D global hybrid code

    Science.gov (United States)

    Lin, Y.; Wing, S.; Johnson, J. R.; Wang, X. Y.; Perez, J. D.; Cheng, L.

    2017-06-01

    Global structure and evolution of flux tube entropy S, integrated over closed field lines, associated with magnetic reconnection in the magnetotail are investigated using the AuburN Global hybrId codE in three dimensions (3-D), ANGIE3D. Flux tubes with decreased entropy, or "bubbles," are found to be generated due to the sudden change of flux tube topology and thus volume in reconnection. By tracking the propagation of the entropy-depleted flux tubes, the roles of the entropy structure in plasma transport to the inner magnetosphere is examined with a self-consistent global hybrid simulation for the first time. The value of S first decreases due to the shortening of flux tubes and then increases due to local ion heating as the bubbles are injected earthward by interchange-ballooning instability, finally oscillating around an equilibrium radial distance where S is nearly the same as the ambient value. The pressure remains anisotropic and not constant along the flux tubes during their propagation with a nonzero heat flux along the field line throughout the duration of the simulation. The correlation of these bubbles with earthward fast flows and specific entropy s is also studied.

  17. Analysis of Hybrid-Integrated High-Speed Electro-Absorption Modulated Lasers Based on EM/Circuit Co-simulation

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Krozer, Viktor; Kazmierski, C.

    2009-01-01

    An improved electromagnetic simulation (EM) based approach has been developed for optimization of the electrical to optical (E/O) transmission properties of integrated electro-absorption modulated lasers (EMLs) aiming at 100 Gbit/s Ethernet applications. Our approach allows for an accurate analys...... of the EML performance in a hybrid microstrip assembly. The established EM-based approach provides a design methodology for the future hybrid integration of the EML with its driving electronics....

  18. Hybrid Particle-Element Simulation of Impact on Composite Orbital Debris Shields

    Science.gov (United States)

    Fahrenthold, Eric P.

    2004-01-01

    This report describes the development of new numerical methods and new constitutive models for the simulation of hypervelocity impact effects on spacecraft. The research has included parallel implementation of the numerical methods and material models developed under the project. Validation work has included both one dimensional simulations, for comparison with exact solutions, and three dimensional simulations of published hypervelocity impact experiments. The validated formulations have been applied to simulate impact effects in a velocity and kinetic energy regime outside the capabilities of current experimental methods. The research results presented here allow for the expanded use of numerical simulation, as a complement to experimental work, in future design of spacecraft for hypervelocity impact effects.

  19. Hybrid Simulations of the Broadband Ground Motions for the 2008 MS8.0 Wenchuan, China, Earthquake

    Science.gov (United States)

    Yu, X.; Zhang, W.

    2012-12-01

    The Ms8.0 Wenchuan earthquake occurred on 12 May 2008 at 14:28 Beijing Time. It is the largest event happened in the mainland of China since the 1976, Mw7.6, Tangshan earthquake. Due to occur in the mountainous area, this great earthquake and the following thousands aftershocks also caused many other geological disasters, such as landslide, mud-rock flow and "quake lakes" which formed by landslide-induced reservoirs. These resulted in tremendous losses of life and property. Casualties numbered more than 80,000 people, and there were major economic losses. However, this earthquake is the first Ms 8 intraplate earthquake with good close fault strong motion coverage. Over four hundred strong motion stations of the National Strong Motion Observation Network System (NSMONS) recorded the mainshock. Twelve of them located within 20 km of the fault traces and another 33 stations located within 100 km. These observations, accompanying with the hundreds of GPS vectors and multiple ALOS INSAR images, provide an unprecedented opportunity to study the rupture process of such a great intraplate earthquake. In this study, we calculate broadband near-field ground motion synthetic waveforms of this great earthquake using a hybrid broadband ground-motion simulation methodology, which combines a deterministic approach at low frequencies (f Green's function calculation approach at high frequency ( ~ 10.0 Hz). The fault rupture is represented kinematically and incorporates spatial heterogeneity in slip, rupture speed, and rise time that were obtained by an inversion kinematic source model. At the same time, based on the aftershock data, we analyze the site effects for the near-field stations. Frequency-dependent site-amplification values for each station are calculated using genetic algorithms. For the calculation of the synthetic waveforms, at first, we carry out simulations using the hybrid methodology for the frequency up to 10.0 Hz. Then, we consider for the soil site simulations

  20. Performance of Irikura Recipe Rupture Model Generator in Earthquake Ground Motion Simulations with Graves and Pitarka Hybrid Approach

    Science.gov (United States)

    Pitarka, Arben; Graves, Robert; Irikura, Kojiro; Miyake, Hiroe; Rodgers, Arthur

    2017-02-01

    We analyzed the performance of the Irikura and Miyake (Pure and Applied Geophysics 168(2011):85-104, 2011) (IM2011) asperity-based kinematic rupture model generator, as implemented in the hybrid broadband ground motion simulation methodology of Graves and Pitarka (Bulletin of the Seismological Society of America 100(5A):2095-2123, 2010), for simulating ground motion from crustal earthquakes of intermediate size. The primary objective of our study is to investigate the transportability of IM2011 into the framework used by the Southern California Earthquake Center broadband simulation platform. In our analysis, we performed broadband (0-20 Hz) ground motion simulations for a suite of M6.7 crustal scenario earthquakes in a hard rock seismic velocity structure using rupture models produced with both IM2011 and the rupture generation method of Graves and Pitarka (Bulletin of the Seismological Society of America, 2016) (GP2016). The level of simulated ground motions for the two approaches compare favorably with median estimates obtained from the 2014 Next Generation Attenuation-West2 Project (NGA-West2) ground motion prediction equations (GMPEs) over the frequency band 0.1-10 Hz and for distances out to 22 km from the fault. We also found that, compared to GP2016, IM2011 generates ground motion with larger variability, particularly at near-fault distances (1 s). For this specific scenario, the largest systematic difference in ground motion level for the two approaches occurs in the period band 1-3 s where the IM2011 motions are about 20-30% lower than those for GP2016. We found that increasing the rupture speed by 20% on the asperities in IM2011 produced ground motions in the 1-3 s bandwidth that are in much closer agreement with the GMPE medians and similar to those obtained with GP2016. The potential implications of this modification for other rupture mechanisms and magnitudes are not yet fully understood, and this topic is the subject of ongoing study. We concluded

  1. Development and validation of a hybrid simulation technique for cone beam CT: application to an oral imaging system

    Science.gov (United States)

    Zhang, G.; Pauwels, R.; Marshall, N.; Shaheen, E.; Nuyts, J.; Jacobs, R.; Bosmans, H.

    2011-09-01

    This paper proposes a hybrid technique to simulate the complete chain of an oral cone beam computed tomography (CBCT) system for the study of both radiation dose and image quality. The model was developed around a 3D Accuitomo 170 unit (J Morita, Japan) with a tube potential range of 60-90 kV. The Monte Carlo technique was adopted to simulate the x-ray generation, filtration and collimation. Exact dimensions of the bow-tie filter were estimated iteratively using experimentally acquired flood images. Non-flat radiation fields for different exposure settings were mediated via 'phase spaces'. Primary projection images were obtained by ray tracing at discrete energies and were fused according to the two-dimensional energy modulation templates derived from the phase space. Coarse Monte Carlo simulations were performed for scatter projections and the resulting noisy images were smoothed by Richardson-Lucy fitting. Resolution and noise characteristics of the flat panel detector were included using the measured modulation transfer function (MTF) and the noise power spectrum (NPS), respectively. The Monte Carlo dose calculation was calibrated in terms of kerma free-in-air about the isocenter, using an ionization chamber, and was subsequently validated by comparison against the measured air kerma in water at various positions of a cylindrical water phantom. The resulting dose discrepancies were found <10% for most cases. Intensity profiles of the experimentally acquired and simulated projection images of the water phantom showed comparable fractional increase over the common area as changing from a small to a large field of view, suggesting that the scatter was accurately accounted. Image validation was conducted using two small phantoms and the built-in quality assurance protocol of the system. The reconstructed simulated images showed high resemblance on contrast resolution, noise appearance and artifact pattern in comparison to experimentally acquired images, with <5

  2. Performance simulation and analysis of a fuel cell/battery hybrid forklift truck

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham; Rokni, Masoud; Advani, Suresh G.

    2013-01-01

    The performance of a forklift truck powered by a hybrid system consisting of a PEM fuel cell and a lead acid battery is modeled and investigated by conducting a parametric study. Various combinations of fuel cell size and battery capacity are employed in conjunction with two distinct control...... strategies to study their effect on hydrogen consumption and battery state-of-charge for two drive cycles characterized by different operating speeds and forklift loads. The results show that for all case studies, the combination of a 110 cell stack with two strings of 55 Ah batteries is the most economical...... choice for the hybrid system based on system size and hydrogen consumption. In addition, it is observed that hydrogen consumption decreases by about 24% when the maximum speed of the drive cycle is decreased from 4.5 to 3 m/s. Similarly, by decreasing the forklift load from 2.5 to 1.5 ton, the hydrogen...

  3. Graphene coated fiber optic surface plasmon resonance biosensor for the DNA hybridization detection: Simulation analysis

    Science.gov (United States)

    Shushama, Kamrun Nahar; Rana, Md. Masud; Inum, Reefat; Hossain, Md. Biplob

    2017-01-01

    In this paper, a graphene coated optical fiber surface plasmon resonance (SPR) biosensor is presented for the detection of DNA Hybridization. For the proposed sensor, a four layer model (fiber core /metal /sensing layer /sample) where a sheet of graphene (biomolecular recognition elements (BRE)) acting as a sensing layer is coated around the gold film because graphene enhances the sensitivity of fiber optic SPR biosensor. Numerical analysis shows the variation of resonance wavelength and spectrum of transmitted power for mismatched DNA strands and for complementary DNA strands. For mismatched DNA strands variation is negligible whereas for complementary DNA strands is considerably countable. Proposed sensor successfully distinguishes hybridization and single nucleotide polymorphisms (SNP) by observing the variation level of resonance wavelength and spectrum of transmitted power.

  4. Micromagnetic simulation of thickness variation of Neel cap in hybrid Bloch-Neel domain wall

    Energy Technology Data Exchange (ETDEWEB)

    Lu Mai [Key Lab. of Opto-Electronic Technology and Intelligent Control, Lanzhou Jiaotong University, Ministry of Education, P.O. Box 73, 118 West Anning Road, Lanzhou 730070, Gansu (China) and Department of Signals and Systems, Chalmers University of Technology, SE-412 96, Gothenburg (Sweden)]. E-mail: m.lu@mail.edu.cn; Leonard, Paul J. [Department of Electronic and Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)

    2005-08-01

    The hybrid Bloch-Neel domain wall in iron film has been investigated using three-dimensional micromagnetic calculations. Magnetization distributions in the film plane and cross-section are presented. In the film plane the rotation of magnetization in the 180 deg domain wall takes two different patterns from the bottom layer to the top layer. In cross-section the C-shaped magnetization distribution with hybrid Bloch-Neel domain wall has been found. The thickness of the top Neel cap changes from its largest value as the C-shaped magnetization distribution appears, and becomes thinner as the C-shaped magnetization distribution gradually moves and grows up. The thickness variation of the bottom Neel cap changes in a similar way, but with a reversal pattern. The results in this paper will enrich our knowledge of magnetic domain and domain wall patterns in magnetic materials.

  5. Scripting approach in hybrid organic-inorganic condensation simulation: the GPTMS proof-of-concept

    OpenAIRE

    Maly, Marek; Posocco, Paola; Fermeglia, Maurizio; Pricl, Sabrina

    2008-01-01

    Abstract Silica-based hybrid organic-inorganic materials prepared by sol-gel chemistry exhibit unique chemical and physical properties by virtue of their anisotropic organization. (3-glycidoxypropyl)trimethoxysilane (GPTMS)-based networks represent an archetype of this class of substances, with a vast range of applications. In the present study, a new computational recipe has been developed within Materials Studio software platform to generate atomistic models of GPTMS crosslinked ...

  6. Modelling Beam Dynamics and RF Production in Two Beam Accelerators with a Hybrid Simulation Tool

    Science.gov (United States)

    Lidia, Steven

    2000-04-01

    A hybrid mapping and PIC code is described and applied to the study of transient-to-steady-state phenomena of beam dynamics and rf power production in relativistic-klystron two-beam accelerators. Beam and beamline parameters appropriate to a single device that produces 40-100 MW per meter over 10 meters with a 120 ns pulse length are described and used.

  7. A Hybrid Model for Multiscale Laser Plasma Simulations with Detailed Collisional Physics

    Science.gov (United States)

    2016-11-29

    other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a ...Briefing Charts 3. DATES COVERED (From - To) 02 November 2016 – 30 November 2016 4. TITLE AND SUBTITLE A Hybrid Model for Multiscale Laser Plasma...Briefing Charts 15. SUBJECT TERMS N/ A 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE

  8. A hybrid modelling approach to simulating foot-and-mouth disease outbreaks in Australian livestock

    Directory of Open Access Journals (Sweden)

    Richard A Bradhurst

    2015-03-01

    Full Text Available Foot-and-mouth disease (FMD is a highly contagious and economically important viral disease of cloven-hoofed animals. Australia's freedom from FMD underpins a valuable trade in live animals and animal products. An outbreak of FMD would result in the loss of export markets and cause severe disruption to domestic markets. The prevention of, and contingency planning for, FMD are of key importance to government, industry, producers and the community. The spread and control of FMD is complex and dynamic due to a highly contagious multi-host pathogen operating in a heterogeneous environment across multiple jurisdictions. Epidemiological modelling is increasingly being recognized as a valuable tool for investigating the spread of disease under different conditions and the effectiveness of control strategies. Models of infectious disease can be broadly classified as: population-based models that are formulated from the top-down and employ population-level relationships to describe individual-level behaviour, individual-based models that are formulated from the bottom-up and aggregate individual-level behaviour to reveal population-level relationships, or hybrid models which combine the two approaches into a single model.The Australian Animal Disease Spread (AADIS hybrid model employs a deterministic equation-based model (EBM to model within-herd spread of FMD, and a stochastic, spatially-explicit agent-based model (ABM to model between-herd spread and control. The EBM provides concise and computationally efficient predictions of herd prevalence and clinical signs over time. The ABM captures the complex, stochastic and heterogeneous environment in which an FMD epidemic operates. The AADIS event-driven hybrid EBM/ABM architecture is a flexible, efficient and extensible framework for modelling the spread and control of disease in livestock on a national scale. We present an overview of the AADIS hybrid approach and a description of the model

  9. Issues regarding the modelling and simulation of hybrid micro grid systems

    Science.gov (United States)

    Szeidert, I.; Filip, I.; Prostean, O.

    2016-02-01

    The main followed objectives within control strategies dedicated to hybrid micro grid systems (wind/hydro/solar), that operate based on maximum power point tracking (MPPT) techniques are to improve the conversion systems efficiency and to maintain the quality of the produced electrical energy (the voltage and power factor control). One of the main goals of maximum power point tracking strategy is to achieve the harvesting of the maximal possible energy within a pre-set time period. In order to implement the control strategies for micro grid systems that operate at time variable parameter, there are usually required specific transducers (anemometer for wind speed measurement, optical rotational transducers, taco generators, etc.). In the technical literature there are presented several variants of the MPPT techniques, which are particularized at several applications (wind energy conversion systems, solar systems, hydro plants and micro grid hybrid systems). The maximum power point tracking implementations are mainly based on two-level architecture. The inferior level controls the primary variables, while the superior level represents the MPPT control structure. In the paper, authors present some micro grid structures proposed at Politehnica University Timisoara within the frame of a research grant. The paper is focused on the application of MPPT strategies on hybrid micro grid systems. There are presented several structures and control strategies and are highlighted their advantages and disadvantages, together with practical implementation guidelines.

  10. Full wave simulations of fast wave mode conversion and lower hybrid wave propagation in tokamaks

    DEFF Research Database (Denmark)

    Wright, J.C.; Bonoli, P.T.; Brambilla, M.;

    2004-01-01

    Fast wave (FW) studies of mode conversion (MC) processes at the ion-ion hybrid layer in toroidal plasmas must capture the disparate scales of the FW and mode converted ion Bernstein and ion cyclotron waves. Correct modeling of the MC layer requires resolving wavelengths on the order of k(perpendi......Fast wave (FW) studies of mode conversion (MC) processes at the ion-ion hybrid layer in toroidal plasmas must capture the disparate scales of the FW and mode converted ion Bernstein and ion cyclotron waves. Correct modeling of the MC layer requires resolving wavelengths on the order of k......). Two full wave codes, a massively-parallel-processor (MPP) version of the TORIC-2D finite Larmor radius code [M. Brambilla, Plasma Phys. Controlled Fusion 41, 1 (1999)] and also an all orders spectral code AORSA2D [E. F. Jaeger , Phys. Plasmas 9, 1873 (2002)], have been developed which for the first......)] to gain new understanding into the nature of FWMC in tokamaks. The massively-parallel-processor version of TORIC is also now capable of running with sufficient resolution to model planned lower hybrid range of frequencies experiments in the Alcator C-Mod. (C) 2004 American Institute of Physics....

  11. Broadband ground motion simulation using a paralleled hybrid approach of Frequency Wavenumber and Finite Difference method

    Science.gov (United States)

    Chen, M.; Wei, S.

    2016-12-01

    The serious damage of Mexico City caused by the 1985 Michoacan earthquake 400 km away indicates that urban areas may be affected by remote earthquakes. To asses earthquake risk of urban areas imposed by distant earthquakes, we developed a hybrid Frequency Wavenumber (FK) and Finite Difference (FD) code implemented with MPI, since the computation of seismic wave propagation from a distant earthquake using a single numerical method (e.g. Finite Difference, Finite Element or Spectral Element) is very expensive. In our approach, we compute the incident wave field (ud) at the boundaries of the excitation box, which surrounding the local structure, using a paralleled FK method (Zhu and Rivera, 2002), and compute the total wave field (u) within the excitation box using a parallelled 2D FD method. We apply perfectly matched layer (PML) absorbing condition to the diffracted wave field (u-ud). Compared to previous Generalized Ray Theory and Finite Difference (Wen and Helmberger, 1998), Frequency Wavenumber and Spectral Element (Tong et al., 2014), and Direct Solution Method and Spectral Element hybrid method (Monteiller et al., 2013), our absorbing boundary condition dramatically suppress the numerical noise. The MPI implementation of our method can greatly speed up the calculation. Besides, our hybrid method also has a potential use in high resolution array imaging similar to Tong et al. (2014).

  12. One-dimensional hybrid simulations of the diamagnetic cavity boundary region of comet Halley

    Science.gov (United States)

    Puhl-Quinn, P.; Cravens, T. E.

    1995-11-01

    A one-dimensional hybrid technique (particle ions and fluid electrons) is used to study the cometary diamagnetic cavity surface (CS). This hybrid study is unique in that it includes the effects of binary ion-ion Coulomb collisions, an important process in the dense inner coma. The equilibrium location of the CS is maintained by a force balance mainly between the ion-neutral drag force and the magnetic pressure gradient force. However, the detailed structure of the CS layer also depends on properties of the plasma such as the thermal pressure. Significant variations of the ion density, ion flow speed, and magnetic field strength take place across the CS boundary layer. Our hybrid code description of the CS structure compares favorably with the data from experiments onboard the Giotto spacecraft. When compared to the magnetohydrodynamical (fluid) results of Cravens (1989), there is good agreement on the ``core'' width of the plasma density enhancement and on the width of the current layer associated with the magnetic field gradient, but a large discrepancy exists in the width of the ion flow speed transition because of the failure of the fluid model to discern particle effects. Related to this, the hybrid code ion density enhancement is not symmetric as a result of a magnetically reflected, backstreaming ion population within the cavity. The core width of this enhancement (Δn) is highly dependent upon the dissociative recombination rate coefficient, and the hybrid results agree to within 20 percent with the fluid model results of Cravens (1989). The width of the velocity transition (Δv), or the ``tail'' of the density enhancement, is determined by the collision time for the backstreaming ions. The effect of Coulomb collisions is to decrease Δv by a factor of 2. The magnetic field transition has a width (ΔB) that is of the order of a few ion gyroradii. Disrupting the ion gyration by including the effects of binary ion-ion Coulomb collisions alters the role of the

  13. A hybrid CFD-DSMC model designed to simulate rapidly rarefying flow fields and its application to physical vapor deposition

    Science.gov (United States)

    Gott, Kevin

    This research endeavors to better understand the physical vapor deposition (PVD) vapor transport process by determining the most appropriate fluidic model to design PVD coating manufacturing. An initial analysis was completed based on the calculation of Knudsen number from titanium vapor properties. The results show a dense Navier-Stokes solver best describes flow near the evaporative source, but the material properties suggest expansion into the chamber may result in a strong drop in density and a rarefied flow close to the substrate. A hybrid CFD-DSMC solver is constructed in OpenFOAM for rapidly rarefying flow fields such as PVD vapor transport. The models are patched together combined using a new patching methodology designed to take advantage of the one-way motion of vapor from the CFD region to the DSMC region. Particles do not return to the dense CFD region, therefore the temperature and velocity can be solved independently in each domain. This novel technique allows a hybrid method to be applied to rapidly rarefying PVD flow fields in a stable manner. Parameter studies are performed on a CFD, Navier-Stokes continuum based compressible solver, a Direct Simulation Monte Carlo (DSMC) rarefied particle solver, a collisionless free molecular solver and the hybrid CFD-DSMC solver. The radial momentum at the inlet and radial diffusion characteristics in the flow field are shown to be the most important to achieve an accurate deposition profile. The hybrid model also shows sensitivity to the shape of the CFD region and rarefied regions shows sensitivity to the Knudsen number. The models are also compared to each other and appropriate experimental data to determine which model is most likely to accurately describe PVD coating deposition processes. The Navier-Stokes solvers are expected to yield backflow across the majority of realistic inlet conditions, making their physics unrealistic for PVD flow fields. A DSMC with improved collision model may yield an accurate

  14. Jovian Plasmas Torus Interaction with Europa. Plasma Wake Structure and Effect of Inductive Magnetic Field: 3D Hybrid Kinetic Simulation

    Science.gov (United States)

    Lipatov, A. S.; Cooper, J F.; Paterson, W. R.; Sittler, E. C., Jr.; Hartle, R. E.; Simpson, David G.

    2013-01-01

    The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect to a variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo Orbiter mission, and for planning flyby and orbital measurements (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa (Cassidy et al., 2007; Shematovich et al., 2005). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions). Photoionization, electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider the models with Oþ þ and Sþ þ background plasma, and various betas for background ions and electrons, and pickup electrons. The majority of O2 atmosphere is thermal with an extended non-thermal population (Cassidy et al., 2007). In this paper, we discuss two tasks: (1) the plasma wake structure dependence on the parameters of the upstream plasma and Europa's atmosphere (model I, cases (a) and (b) with a homogeneous Jovian magnetosphere field, an inductive magnetic dipole and high oceanic shell conductivity); and (2) estimation of the possible effect of an induced magnetic field arising from oceanic shell conductivity. This effect was estimated based on the difference between the observed and modeled magnetic fields (model II, case (c) with an inhomogeneous Jovian magnetosphere field, an inductive

  15. Data of NODDI diffusion metrics in the brain and computer simulation of hybrid diffusion imaging (HYDI acquisition scheme

    Directory of Open Access Journals (Sweden)

    Chandana Kodiweera

    2016-06-01

    Full Text Available This article provides NODDI diffusion metrics in the brains of 52 healthy participants and computer simulation data to support compatibility of hybrid diffusion imaging (HYDI, “Hybrid diffusion imaging” [1] acquisition scheme in fitting neurite orientation dispersion and density imaging (NODDI model, “NODDI: practical in vivo neurite orientation dispersion and density imaging of the human brain” [2]. HYDI is an extremely versatile diffusion magnetic resonance imaging (dMRI technique that enables various analyzes methods using a single diffusion dataset. One of the diffusion data analysis methods is the NODDI computation, which models the brain tissue with three compartments: fast isotropic diffusion (e.g., cerebrospinal fluid, anisotropic hindered diffusion (e.g., extracellular space, and anisotropic restricted diffusion (e.g., intracellular space. The NODDI model produces microstructural metrics in the developing brain, aging brain or human brain with neurologic disorders. The first dataset provided here are the means and standard deviations of NODDI metrics in 48 white matter region-of-interest (ROI averaging across 52 healthy participants. The second dataset provided here is the computer simulation with initial conditions guided by the first dataset as inputs and gold standard for model fitting. The computer simulation data provide a direct comparison of NODDI indices computed from the HYDI acquisition [1] to the NODDI indices computed from the originally proposed acquisition [2]. These data are related to the accompanying research article “Age Effects and Sex Differences in Human Brain White Matter of Young to Middle-Aged Adults: A DTI, NODDI, and q-Space Study” [3].

  16. Hybrid Electro-Mechanical Simulation Tool for Wind Turbine Generators: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M.; Muljadi, E.; Jonkman, J.

    2013-05-01

    This paper describes the use of MATLAB/Simulink to simulate the electrical and grid-related aspects of a WTG and the FAST aero-elastic wind turbine code to simulate the aerodynamic and mechanical aspects of the WTG. The combination of the two enables studies involving both electrical and mechanical aspects of the WTG.

  17. Histological characterization of gell formation and lesion development on leaves of Phaseolus vulgaris and clones of hybrid poplar after exposure to simulated sulfate acid rain

    Energy Technology Data Exchange (ETDEWEB)

    Dacosta, F.

    1978-01-01

    Histological investigations with leaves of several hybrid poplar clones illustrate gall formations in response to simulated acid rain that result from hyperplasia and hypertrophy of mesophyll cells. Similar experiments with phaseolus vulgaris and clones of hybrid poplar show a sequence of events that follow a general pattern of adaxial epidermis destruction, injury to palisade parenchyma and eventual destruction of more interior tissues after continued exposure to one, six-minute, rain event daily. Results show that most (95%) lesions on Phaseolus vulgaris developed near trichomes and stomata after exposure to the simulated acid rain.

  18. A One-Dimensional Hybrid Simulation of DC/RF Combined Driven Capacitive Plasma%A One-Dimensional Hybrid Simulation of DC/RF Combined Driven Capacitive Plasma

    Institute of Scientific and Technical Information of China (English)

    王帅; 徐翔; 王友年

    2012-01-01

    We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasma density distribution, ion energy distributions (IEDs) and ion angle distributions (IADs) on both the RF and DC electrodes. The increase in DC voltage drives more high-energy ions to the electrode applied to the DC source, which makes the IEDs at the DC electrode shift towards higher energy, and the peaks in the IADs shift towards small angle regions. At the same time, it also decreases the ion energy at the RF electrode and enlarges the incident angles of the ions, which strike the RF electrode.

  19. Experiments, modeling and simulation of the magnetic behavior of inhomogeneously coated nickel/aluminum hybrid foams

    Energy Technology Data Exchange (ETDEWEB)

    Jung, A., E-mail: anne.jung@mx.uni-saarland.de [Universität des Saarlandes, Institute of Applied Mechanics, Campus A4 2, 66123 Saarbrücken (Germany); Klis, D., E-mail: d.klis@lte.uni-saarland.de [Universität des Saarlandes, Laboratory for Electromagnetic Theory, Campus C6 3, 66123 Saarbrücken (Germany); Goldschmidt, F., E-mail: f.goldschmidt@mx.uni-saarland.de [Universität des Saarlandes, Institute of Applied Mechanics, Campus A4 2, 66123 Saarbrücken (Germany)

    2015-03-15

    Open-cell metal foams are used as lightweight construction elements, energy absorbers or as support for catalytic coatings. Coating of open-cell metal foams is not only used for catalytic applications, but it leads also to tremendous increase in stiffness and energy absorption capacity. A non-line of sight coating technique for complex 3D structures is electrodeposition. Unfortunately, due to the 3D porosity and the related problems in mass transport limitation during the deposition, it is not possible to produce homogeneously coated foams. In the present contribution, we present a semi-non-destructive technique applicable to determine the coating thickness distribution of magnetic coatings by measuring the remanent magnetic field of coated foams. In order to have a closer look at the mass transport mechanism, a numerical model was developed to predict the field scans for different coating thickness distributions in the foams. For long deposition times the deposition reaches a steady state whereas a Helmholtz equation is sufficient to predict the coating thickness distribution. The applied current density could be identified as the main influencing parameter. Based on the developed model, it is possible to improve the electrodeposition process and hence the homogeneity in the coating thickness of coated metal foams. This leads to enhanced mechanical properties of the hybrid foams and contributes to better and resource-efficient energy absorbers and lightweight materials. - Highlights: • Production of hybrid foams by electrodeposition of nickel on open-cell metal foams. • Magnetic field scans for visualization of spatial coating thickness distribution. • Modeling of magnetic fields of inhomogeneously coated hybrid foams. • Investigation of mass transport limitation during coating by a Helmholtz equation. • Increasing coating homogeneity by use of low current densities and deposition rates.

  20. Efficient Mooring Line Fatigue Analysis Using a Hybrid Method Time Domain Simulation Scheme

    DEFF Research Database (Denmark)

    Christiansen, Niels Hørbye; Voie, Per Erlend Torbergsen; Høgsberg, Jan Becker;

    2013-01-01

    Dynamic analyses of mooring line systems are computationally expensive. Over the last decades an extensive variety of methods to reduce this computational cost have been suggested. One method that has shown promising preliminary results is a hybrid method which combines finite element analysis...... and slow drift motion. The method is tested on a mooring line system of a floating offshore platform. After training a full fatigue analysis is carried out. The results show that the ANN with high precision provides top tension force histories two orders of magnitude faster than a full dynamic analysis...

  1. Qualitative studies

    National Research Council Canada - National Science Library

    Qualitative Studies (QS) aims to become a central forum for discussions of qualitative research in psychology, education, communication, cultural studies, health sciences and social sciences in general...

  2. Modeling and simulation of stand-alone hybrid power system with fuzzy MPPT for remote load application

    Directory of Open Access Journals (Sweden)

    Bogaraj T.

    2015-09-01

    Full Text Available Many parts of remote locations in the world are not electrified even in this Advanced Technology Era. To provide electricity in such remote places renewable hybrid energy systems are very much suitable. In this paper PV/Wind/Battery Hybrid Power System (HPS is considered to provide an economical and sustainable power to a remote load. HPS can supply the maximum power to the load at a particular operating point which is generally called as Maximum Power Point (MPP. Fuzzy Logic based MPPT (FLMPPT control method has been implemented for both Solar and Wind Power Systems. FLMPPT control technique is implemented to generate the optimal reference voltage for the first stage of DC-DC Boost converter in both the PV and Wind energy system. The HPS is tested with variable solar irradiation, temperature, and wind speed. The FLMPPT method is compared with P&O MPPT method. The proposed method provides a good maximum power operation of the hybrid system at all operating conditions. In order to combine both sources, the DC bus voltage is made constant by employing PI Controllers for the second stage of DC-DC Buck-Boost converter in both Solar and Wind Power Systems. Battery Bank is used to store excess power from Renewable Energy Sources (RES and to provide continuous power to load when the RES power is less than load power. A SPWM inverter is designed to convert DC power into AC to supply three phase load. An LC filter is also used at the output of inverter to get sinusoidal current from the PWM inverter. The entire system was modeled and simulated in Matlab/Simulink Environment. The results presented show the validation of the HPS design.

  3. (I Can’t Get No) Saturation: A simulation and guidelines for sample sizes in qualitative research

    NARCIS (Netherlands)

    van Rijnsoever, Frank J.|info:eu-repo/dai/nl/314100334

    2017-01-01

    I explore the sample size in qualitative research that is required to reach theoretical saturation. I conceptualize a population as consisting of sub-populations that contain different types of information sources that hold a number of codes. Theoretical saturation is reached after all the codes in

  4. (I Can’t Get No) Saturation: A Simulation and Guidelines for Minimum Sample Sizes in Qualitative Research

    NARCIS (Netherlands)

    van Rijnsoever, F.J.

    2015-01-01

    This paper explores the sample size in qualitative research that is required to reach theoretical saturation. I conceptualize a population as consisting of sub-populations that contain different types of information sources that hold a number of codes. Theoretical saturation is reached after all the

  5. (I Can’t Get No) Saturation: A Simulation and Guidelines for Minimum Sample Sizes in Qualitative Research

    NARCIS (Netherlands)

    van Rijnsoever, F.J.

    2015-01-01

    This paper explores the sample size in qualitative research that is required to reach theoretical saturation. I conceptualize a population as consisting of sub-populations that contain different types of information sources that hold a number of codes. Theoretical saturation is reached after all the

  6. Comparative Simulation Study of Production Scheduling in the Hybrid and the Parallel Flow

    Directory of Open Access Journals (Sweden)

    Varela Maria L.R.

    2017-06-01

    Full Text Available Scheduling is one of the most important decisions in production control. An approach is proposed for supporting users to solve scheduling problems, by choosing the combination of physical manufacturing system configuration and the material handling system settings. The approach considers two alternative manufacturing scheduling configurations in a two stage product oriented manufacturing system, exploring the hybrid flow shop (HFS and the parallel flow shop (PFS environments. For illustrating the application of the proposed approach an industrial case from the automotive components industry is studied. The main aim of this research to compare results of study of production scheduling in the hybrid and the parallel flow, taking into account the makespan minimization criterion. Thus the HFS and the PFS performance is compared and analyzed, mainly in terms of the makespan, as the transportation times vary. The study shows that the performance HFS is clearly better when the work stations’ processing times are unbalanced, either in nature or as a consequence of the addition of transport times just to one of the work station processing time but loses advantage, becoming worse than the performance of the PFS configuration when the work stations’ processing times are balanced, either in nature or as a consequence of the addition of transport times added on the work stations’ processing times. This means that physical layout configurations along with the way transport time are including the work stations’ processing times should be carefully taken into consideration due to its influence on the performance reached by both HFS and PFS configurations.

  7. Hybrid heating systems optimization of residential environment to have thermal comfort conditions by numerical simulation.

    Science.gov (United States)

    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.

  8. Wind Energy System Time-domain (WEST) analyzers using hybrid simulation techniques

    Science.gov (United States)

    Hoffman, J. A.

    1979-01-01

    Two stand-alone analyzers constructed for real time simulation of the complex dynamic characteristics of horizontal-axis wind energy systems are described. Mathematical models for an aeroelastic rotor, including nonlinear aerodynamic and elastic loads, are implemented with high speed digital and analog circuitry. Models for elastic supports, a power train, a control system, and a rotor gimbal system are also included. Limited correlation efforts show good comparisons between results produced by the analyzers and results produced by a large digital simulation. The digital simulation results correlate well with test data.

  9. Optimized Mooring Line Simulation Using a Hybrid Method Time Domain Scheme

    DEFF Research Database (Denmark)

    Christiansen, Niels Hørbye; Voie, Per Erlend Torbergsen; Høgsberg, Jan;

    2014-01-01

    of mooring lines by two orders of magnitude. The present study shows how an ANN trained to perform nonlinear dynamic response simulation can be optimized using a method known as optimal brain damage (OBD) and thereby be used to rank the importance of all analysis input. Both the training and the optimization...... of the ANN are based on one short time domain simulation sequence generated by a FEM model of the structure. This means that it is possible to evaluate the importance of input parameters based on this single simulation only. The method is tested on a numerical model of mooring lines on a floating offshore...

  10. Goals, Success Factors, and Barriers for Simulation-Based Learning: A Qualitative Interview Study in Health Care

    Science.gov (United States)

    Dieckmann, Peter; Friis, Susanne Molin; Lippert, Anne; Ostergaard, Doris

    2012-01-01

    Introduction: This study describes (a) process goals, (b) success factors, and (c) barriers for optimizing simulation-based learning environments within the simulation setting model developed by Dieckmann. Methods: Seven simulation educators of different experience levels were interviewed using the Critical Incident Technique. Results: (a) The…

  11. The "Virtual ChemLab" Project: A Realistic and Sophisticated Simulation of Organic Synthesis and Organic Qualitative Analysis

    Science.gov (United States)

    Woodfield, Brian F.; Andrus, Merritt B.; Waddoups, Gregory L.; Moore, Melissa S.; Swan, Richard; Allen, Rob; Bodily, Greg; Andersen, Tricia; Miller, Jordan; Simmons, Bryon; Stanger, Richard

    2005-01-01

    A set of sophisticated and realistic laboratory simulations is created for use in freshman- and sophomore-level chemistry classes and laboratories called 'Virtual ChemLab'. A detailed assessment of student responses is provided and the simulation's pedagogical utility is described using the organic simulation.

  12. Computational modelling of six speed hybrid gear box and its simulation using Simulinkas an interactive tool of MATLAB

    Directory of Open Access Journals (Sweden)

    Devesh Ramphal Upadhyay

    2016-02-01

    Full Text Available The paper introduces an idea which adds itself into contribution of getting best fuel economy of a passenger car when it is running at high speed on a highway. A six speed (forward gear box is addressed in the paper which is controlled manually and automatically as well. The paper introduces an advancement in manual transmission gear box for passenger cars. Hydraulic circuit is designed with mechatronics point of view and resulting in making the shifting of gear automatically. A computational design is made of the Hybrid Gear Box (HGB using CATIA P3 V5 as a designing software. A new gear meshing in 5 speed manual transmission gear box which synchronizes with the output shaft of the transmission automatically after getting command by the automated system designed. Parameters are considered on the basis of practical model and is been simulated by using Simdriveline as the Simulink tool of MATLAB r2010a. The mechanical properties of the components of the hybrid gear box is calculated on the basis of the functional parameters and with help of the fundamental and dependent properties formulation. The final result is the graphical analysis of the model forobtaining at least 15% fuel efficient than any of the vehicle of same configurations.

  13. Molecular dynamics simulations on the relationship between the elastic parameters and the molecular structures of nano-hybrid POSS materials

    Institute of Scientific and Technical Information of China (English)

    ZENG Fan-lin; SUN Yi; HU Li-jiang

    2006-01-01

    To research the relationship between the elastic parameters and the molecular structures of nano hybrid polyhedral oligomeric silsesquioxanes (POSS) materials, the mechanical properties at different temperatures for three POSS polymers with different molecular architectures, polymerlized norbornene POSS homopolymer (PNPOSS, pedant architecture), γ - (2, 3 glycidoxy) propyl diaminoethane POSS polymer (GPDP, catena architecture) and trimethoxysilylcyclopentyl POSS polymer (TSCP, cage -cage network architecture) were obtained by molecular dynamics simulations based on the Compass force-field. Results indicate that the molecular architectures of the POSS polymers have great influence on the reinforced effects. The effect of the cage-cage network architecture is best, while that of the catena architecture takes second place and the pedant architecture has the least influence comparatively. The reinforced effects of the POSS monomers were examined. The influences of the temperatures on these effects were analyzed also. It may provide some basis for the reasonable applications of the excellent mechanical properties of the organic-inorganic nano-hybrid materials. It may also provide references for exploitation and design of the POSS materials.

  14. Determination of the Operating Envelope for a Direct Fired Fuel Cell Turbine Hybrid Using Hardware Based Simulation

    Energy Technology Data Exchange (ETDEWEB)

    David Tucker; Eric Liese; Randall Gemmen

    2009-02-10

    The operating range of a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid with bypass control of cathode airflow was determined using a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). Three methods of cathode airflow management using bypass valves in a hybrid power system were evaluated over the maximum range of operation. The cathode air flow was varied independently over the full range of operation of each bypass valve. Each operating point was taken at a steady state condition and was matched to the thermal, pressure and flow output of a corresponding fuel cell operation condition. Turbine electric load was also varied so that the maximum range of fuel cell operation could be studied, and a preliminary operating map could be made. Results are presented to show operating envelopes in terms of cathode air flow, fuel cell and turbine load, and compressor surge margin to be substantial.

  15. Simulative Study into the Development of a Hybrid HVDC System Through a Comparative Research with HVAC: a Futuristic Approach

    Directory of Open Access Journals (Sweden)

    R. S. Narayan

    2017-06-01

    Full Text Available High Voltage Direct Current Transmission (HVDC is considered a better solution for bulk long distance transmissions. The increased use of HVDC is a result of its advantages over the HVAC systems and especially of its fault stability nature. A better solution is proposed by using a Voltage Source Controlled–HVDC as one of the infeed for the Multi-Infeed HVDC (MIDC or MI-HVDC systems. The main advantage with the VSC converter is its flexible power control which enhances the stability of the MIDC systems. In this paper, the behavior of an HVDC system is compared with that of an HVAC during faults. A Hybrid HVDC system that includes a LCC as a rectifier unit and a VSC converter as the inverter is being proposed. It is considered suitable for MIDC systems and particularly for supplying a weak AC system. The performance of the system during steady state and transient conditions for all the proposed topologies including HVDC, HVAC and Hybrid HVDC are studied in MATLAB/SIMULINK. All of the proposed control strategies are evaluated via a series of simulation case studies.

  16. Modelling and Simulation of a Hybrid Solid Oxide Fuel Cell Coupled with a Gas Turbine Power Plant

    Directory of Open Access Journals (Sweden)

    Luca Andreassi

    2009-09-01

    Full Text Available

    The paper presents a simulation of a hybrid solid oxide fuel cell-gas turbine (SOFC-GT power generation system fueled by natural gas. In the system considered, the unreacted fuel from a topping solid oxide fuel cell is burnt in an afterburner to feed a bottoming gas turbine and produce additional power. Combustion gas expands in the gas turbine after having preheated the inlet air and fuel and it is used to generate steam required by the reforming reactions. A novel thermodynamic model has been developed for the fuel cell and implemented into the library of a modular object-oriented Process Simulator, CAMELPro™. The relevant plant performance indicators have been analyzed to evaluate the incremental increase in efficiency brought about by the introduction of the gas turbine and heat regeneration system. Simulations were performed for different values of the main plant parameters.

    • This paper is an updated version of a paper published in the ECOS'08 proceedings. 

  17. 2D hybrid simulations of super-diffusion at the magnetopause driven by Kelvin-Helmholtz instability

    Energy Technology Data Exchange (ETDEWEB)

    Cowee, Misa M [Los Alamos National Laboratory; Winske, Dan [Los Alamos National Laboratory; Gary, S Peter [Los Alamos National Laboratory

    2009-01-01

    This manuscript describes the self-consistent simulation of diffusion at the magnetopause driven by Kelvin-Helmholtz (KH) instability. Two-dimensional hybrid (kinetic ions, fluid electrons) simulations of the most KH-unstable configuration where the shear flow is oriented perpendicular to the uniform magnetic field are carried out. The motion of the simulation particles are tracked during the run and their mean-square displacement normal to the magnetopause is calculated from which diffusion coefficients are determined. The diffusion coefficients are found to be time dependent, with D{sub x} {proportional_to} t{sup {alpha}}, where {alpha} > 1. Additionally, the probability distribution functions (PDF) of the 'jump lengths' the particles make over time are found to be non-gaussian. Such time-dependent diffusion coefficients and non-gaussian PDF's have been associated with so-called 'super-diffusion', in which diffusive mixing of particles is enhanced over classical diffusion. The results indicate that while turbulence associated with the break-down of vortices contributes to this enhanced diffusion, it is the growth of large-scale, coherent vortices is the more important process in facilitating it.

  18. A closed-loop forward osmosis-nanofiltration hybrid system: Understanding process implications through full-scale simulation

    KAUST Repository

    Phuntsho, Sherub

    2016-12-30

    This study presents simulation of a closed-loop forward osmosis (FO)-nanofiltration (NF) hybrid system using fertiliser draw solution (DS) based on thermodynamic mass balance in a full-scale system neglecting the non-idealities such as finite membrane area that may exist in a real process. The simulation shows that the DS input parameters such as initial concentrations and its flow rates cannot be arbitrarily selected for a plant with defined volume output. For a fixed FO-NF plant capacity and feed concentration, the required initial DS flow rate varies inversely with the initial DS concentration or vice-versa. The net DS mass flow rate, a parameter constant for a fixed plant capacity but that increases linearly with the plant capacity and feed concentration, is the most important operational parameter of a closed-loop system. Increasing either of them or both increases the mass flow rate to the system directly affecting the final concentration of the diluted DS with direct energy implications to the NF process. Besides, the initial DS concentration and flow rates are also limited by the optimum recovery rates at which NF process can be operated which otherwise also have direct implications to the NF energy. This simulation also presents quantitative analysis of the reverse diffusion of fertiliser nutrients towards feed brine and the gradual accumulation of feed solutes within the closed system.

  19. Hybrid (particle in cell-fluid) simulation of ion-acoustic soliton generation including super-thermal and trapped electrons

    Energy Technology Data Exchange (ETDEWEB)

    Nopoush, M.; Abbasi, H. [Faculty of Physics, Amirkabir University of Technology, P. O. Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2011-08-15

    The present paper is devoted to the simulation of the nonlinear disintegration of a localized perturbation into an ion-acoustic soliton in a plasma. Recently, this problem was studied by a simple model [H. Abbasi et al., Plasma Phys. Controlled Fusion 50, 095007 (2008)]. The main assumptions were (i) in the electron velocity distribution function (DF), the ion-acoustic soliton velocity was neglected in comparison to the electron thermal velocity, (ii) on the ion-acoustic evolution time-scale, the electron velocity DF was assumed to be stationary, and (iii) the calculation was restricted to the small amplitude case. In order to generalize the model, one has to consider the evolution of the electron velocity DF for finite amplitudes. For this purpose, a one dimensional electrostatic hybrid code, particle in cell (PIC)-fluid, was designed. It simulates the electrons dynamics by the PIC method and the cold ions dynamics by the fluid equations. The plasma contains a population of super-thermal electrons and, therefore, a Lorentzian (kappa) velocity DF is used to model the high energy tail in the electron velocity DF. Electron trapping is included in the simulation in view of their nonlinear resonant interaction with the localized perturbation. A Gaussian initial perturbation is used to model the localized perturbation. The influence of both the trapped and the super-thermal electrons on this process is studied and compared with the previous model.

  20. Hybrid Finite-Discrete Element Simulation of the EDZ Formation and Mechanical Sealing Process Around a Microtunnel in Opalinus Clay

    Science.gov (United States)

    Lisjak, Andrea; Tatone, Bryan S. A.; Mahabadi, Omid K.; Grasselli, Giovanni; Marschall, Paul; Lanyon, George W.; Vaissière, Rémi de la; Shao, Hua; Leung, Helen; Nussbaum, Christophe

    2016-05-01

    The analysis and prediction of the rock mass disturbance around underground excavations are critical components of the performance and safety assessment of deep geological repositories for nuclear waste. In the short term, an excavation damaged zone (EDZ) tends to develop due to the redistribution of stresses around the underground openings. The EDZ is associated with an increase in hydraulic conductivity of several orders of magnitude. In argillaceous rocks, sealing mechanisms ultimately lead to a partial reduction in the effective hydraulic conductivity of the EDZ with time. The goal of this study is to strengthen the understanding of the phenomena involved in the EDZ formation and sealing in Opalinus Clay, an indurated claystone currently being assessed as a host rock for a geological repository in Switzerland. To achieve this goal, hybrid finite-discrete element method (FDEM) simulations are performed. With its explicit consideration of fracturing processes, FDEM modeling is applied to the HG-A experiment, an in situ test carried out at the Mont Terri underground rock laboratory to investigate the hydro-mechanical response of a backfilled and sealed microtunnel. A quantitative simulation of the EDZ formation process around the microtunnel is first carried out, and the numerical results are compared with field observations. Then, the re-compression of the EDZ under the effect of a purely mechanical loading, capturing the increase of swelling pressure from the backfill onto the rock, is considered. The simulation results highlight distinctive rock failure kinematics due to the bedded structure of the rock mass. Also, fracture termination is simulated at the intersection with a pre-existing discontinuity, representing a fault plane oblique to the bedding orientation. Simulation of the EDZ re-compression indicates an overall reduction of the total fracture area as a function of the applied pressure, with locations of ineffective sealing associated with self

  1. Hybrid Simulation Environment for Construction Projects: Identification of System Design Criteria

    Directory of Open Access Journals (Sweden)

    Mohamed Moussa

    2014-01-01

    Full Text Available Large construction projects are complex, dynamic, and unpredictable. They are subject to external and uncontrollable events that affect their schedule and financial outcomes. Project managers take decisions along the lifecycle of the projects to align with projects objectives. These decisions are data dependent where data change over time. Simulation-based modeling and experimentation of such dynamic environment are a challenge. Modeling of large projects or multiprojects is difficult and impractical for standalone computers. This paper presents the criteria required in a simulation environment suitable for modeling large and complex systems such as construction projects to support their lifecycle management. Also presented is a platform that encompasses the identified criteria. The objective of the platform is to facilitate and simplify the simulation and modeling process and enable the inclusion of complexity in simulation models.

  2. Simulation of Noise-Cancelling in the Cockpit of an Aircraft Using Two-Rate Hybrid Neural Network

    Directory of Open Access Journals (Sweden)

    ASTROV, I.

    2007-11-01

    Full Text Available This paper presents the two-rate hybrid neural network (TRHNN for processing of noisy signal. The received TRHNN consists of "fast" ADAptive LInear NEuron neural network (FADALINENN and "slow" radial basis neural network (SRBNN. The illustrative design example - noise-cancelling of noisy pilot's voice pattern - was carried out using the TRHNN. The received TRHNN has high speed of signal processing. This example demonstrates that the proposed TRHNN is capable not only to recognize the pilot's voice in the noisy voice pattern, but also to restore the pilot's voice. The simulation results with use the software package Simulink show the computing procedure and applicability of the TRHNNs for fast-acting signal processing and analysis in real-time flight conditions.

  3. Implementation of real-time energy management strategy based on reinforcement learning for hybrid electric vehicles and simulation validation.

    Science.gov (United States)

    Kong, Zehui; Zou, Yuan; Liu, Teng

    2017-01-01

    To further improve the fuel economy of series hybrid electric tracked vehicles, a reinforcement learning (RL)-based real-time energy management strategy is developed in this paper. In order to utilize the statistical characteristics of online driving schedule effectively, a recursive algorithm for the transition probability matrix (TPM) of power-request is derived. The reinforcement learning (RL) is applied to calculate and update the control policy at regular time, adapting to the varying driving conditions. A facing-forward powertrain model is built in detail, including the engine-generator model, battery model and vehicle dynamical model. The robustness and adaptability of real-time energy management strategy are validated through the comparison with the stationary control strategy based on initial transition probability matrix (TPM) generated from a long naturalistic driving cycle in the simulation. Results indicate that proposed method has better fuel economy than stationary one and is more effective in real-time control.

  4. SiSeRHMap v1.0: a simulator for mapped seismic response using a hybrid model

    Directory of Open Access Journals (Sweden)

    G. Grelle

    2015-06-01

    Full Text Available SiSeRHMap is a computerized methodology capable of drawing up prediction maps of seismic response. It was realized on the basis of a hybrid model which combines different approaches and models in a new and non-conventional way. These approaches and models are organized in a code-architecture composed of five interdependent modules. A GIS (Geographic Information System Cubic Model (GCM, which is a layered computational structure based on the concept of lithodynamic units and zones, aims at reproducing a parameterized layered subsoil model. A metamodeling process confers a hybrid nature to the methodology. In this process, the one-dimensional linear equivalent analysis produces acceleration response spectra of shear wave velocity-thickness profiles, defined as trainers, which are randomly selected in each zone. Subsequently, a numerical adaptive simulation model (Spectra is optimized on the above trainer acceleration response spectra by means of a dedicated Evolutionary Algorithm (EA and the Levenberg–Marquardt Algorithm (LMA as the final optimizer. In the final step, the GCM Maps Executor module produces a serial map-set of a stratigraphic seismic response at different periods, grid-solving the calibrated Spectra model. In addition, the spectra topographic amplification is also computed by means of a numerical prediction model. This latter is built to match the results of the numerical simulations related to isolate reliefs using GIS topographic attributes. In this way, different sets of seismic response maps are developed, on which, also maps of seismic design response spectra are defined by means of an enveloping technique.

  5. Energy loss and coronary flow simulation following hybrid stage I palliation: a hypoplastic left heart computational fluid dynamic model.

    Science.gov (United States)

    Shuhaiber, Jeffrey H; Niehaus, Justin; Gottliebson, William; Abdallah, Shaaban

    2013-08-01

    The theoretical differences in energy losses as well as coronary flow with different band sizes for branch pulmonary arteries (PA) in hypoplastic left heart syndrome (HLHS) remain unknown. Our objective was to develop a computational fluid dynamic model (CFD) to determine the energy losses and pulmonary-to-systemic flow rates. This study was done for three different PA band sizes. Three-dimensional computer models of the hybrid procedure were constructed using the standard commercial CFD softwares Fluent and Gambit. The computer models were controlled for bilateral PA reduction to 25% (restrictive), 50% (intermediate) and 75% (loose) of the native branch pulmonary artery diameter. Velocity and pressure data were calculated throughout the heart geometry using the finite volume numerical method. Coronary flow was measured simultaneously with each model. Wall shear stress and the ratio of pulmonary-to-systemic volume flow rates were calculated. Computer simulations were compared at fixed points utilizing echocardiographic and catheter-based metric dimensions. Restricting the PA band to a 25% diameter demonstrated the greatest energy loss. The 25% banding model produced an energy loss of 16.76% systolic and 24.91% diastolic vs loose banding at 7.36% systolic and 17.90% diastolic. Also, restrictive PA bands had greater coronary flow compared with loose PA bands (50.2 vs 41.9 ml/min). Shear stress ranged from 3.75 Pascals with restrictive PA banding to 2.84 Pascals with loose banding. Intermediate PA banding at 50% diameter achieved a Qp/Qs (closest to 1) at 1.46 systolic and 0.66 diastolic compared with loose or restrictive banding without excess energy loss. CFD provides a unique platform to simulate pressure, shear stress as well as energy losses of the hybrid procedure. PA banding at 50% provided a balanced pulmonary and systemic circulation with adequate coronary flow but without extra energy losses incurred.

  6. Reclaimed water quality during simulated ozone-managed aquifer recharge hybrid

    KAUST Repository

    Yoon, Min

    2014-06-17

    A synergistic hybrid of two treatment processes, managed aquifer recharge (MAR) combined with ozonation, was proposed for wastewater reclamation and water reuse applications. Batch reactor and soil-column experiments were performed to evaluate reclaimed water quality using various chemical and bacterial analyses. The ozone process was optimized at low ozone dose (0.5 mg O3/mg DOC) based on the control of N-nitrosodimethylamine (<5 ng L-1) and bromate (<10 μg L-1), and applied prior to (i.e., O3-MAR) and after MAR (i.e., MAR-O3). This work demonstrates that effluent organic matter (EfOM) and trace organic contaminants (TOrCs) are effectively removed during the hybrid process of MAR combined ozonation, compared to MAR only. Based on fluorescence excitation-emission matrices analyses, both MAR and ozonation reduce soluble microbial (protein-like) products while only ozonation contributes in reducing humic and fulvic substances. Even at low ozone dose of 0.5 mg O3/mg DOC, the O3-MAR hybrid significantly reduced UV absorbance by ≥2 m-1, BDOC by ≥64 %, and total (Σ) TOrC concentrations by ≥70 % in the effluent water quality. However, no significant improvement (<10 %) in the removal of Σ16 TOrC concentrations was observed for the increased ozone dose at 1.0 mg O3/mg DOC during MAR combined ozonation processes. Overall, O3-MAR was effective by 10-30 % in treating effluent water than MAR based on DOC, UV254 nm EfOM, TOrC and bacterial analyses. In addition, MAR-O3 was better than O3-MAR for the reduction of fluorescence (close MQ), TOrCs (≥74 %) and total bacteria cell concentrations (>3 log reduction). Therefore, implementing MAR prior to ozonation appears to remove the bio-amenable compounds that react rapidly with ozone, thereby reducing oxidant demand and treatment efficiency. © 2014 Springer-Verlag Berlin Heidelberg.

  7. 3D hybrid simulations with gyrokinetic particle ions and fluid electrons

    Energy Technology Data Exchange (ETDEWEB)

    Belova, E.V.; Park, W.; Fu, G.Y. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Strauss, H.R. [New York Univ., NY (United States); Sugiyama, L.E. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1998-12-31

    The previous hybrid MHD/particle model (MH3D-K code) represented energetic ions as gyrokinetic (or drift-kinetic) particles coupled to MHD equations using the pressure or current coupling scheme. A small energetic to bulk ion density ratio was assumed, n{sub h}/n{sub b} {much_lt} 1, allowing the neglect of the energetic ion perpendicular inertia in the momentum equation and the use of MHD Ohm`s law E = {minus}v{sub b} {times} B. A generalization of this model in which all ions are treated as gyrokinetic/drift-kinetic particles and fluid description is used for the electron dynamics is considered in this paper.

  8. Hybrid simulations of whistler waves generation and current closure by a pulsed tether in the ionosphere

    Science.gov (United States)

    Chang, C. L.; Lipatov, A. S.; Drobot, A. T.; Papadopoulos, K.; Satya-Narayana, P.

    1994-01-01

    The dynamic response of a magnetized collisionless plasma to an externally driven, finite size, sudden switch-on current source across the magnetic field has been studied using a two dimensional hybrid code. It was found that the predominant plasma response was the excitation of whistler waves and the formation of current closure by induced currents in the plasma. The results show that the current closure path consists of: (a) two antiparallel field-aligned current channels at the end of the imposed current sheet; and (b) a cross-field current region connecting these channels. The formation of the current closure path occured in the whistler timescale much shorter than that of MHD and the closure region expanded continuously in time. The current closure process was accompanied by significant energy loss due to whistler radiation.

  9. Effects of preoperative simulation on minimally invasive Hybrid Lumbar Interbody Fusion (MIS-HLIF).

    Science.gov (United States)

    Rieger, Bernhard; Jiang, Hongzhen; Reinshagen, Clemens; Molcanyi, Marek; Zivcak, Jozef; Grönemeyer, Dietrich; Bosche, Bert; Schackert, Gabriele; Ruess, Daniel

    2017-07-10

    The main focus of this study was to evaluate how preoperative simulation affects the surgical workflow, radiation exposure and outcome of MIS-HLIF. 132 patients who underwent single level MIS-HLIF were enrolled in a cohort study design. Dose area product was analyzed in addition to surgical data. Once preoperative simulation was established, 66 cases (SIM cohort) were compared with 66 patients who had previously undergone MIS-HLIF without preoperative simulation (NO-SIM cohort). Dose area product was reduced considerably in the SIM cohort (320 cGy·cm(2) NO-SIM cohort: 470 cGy·cm(2); p<0.01). Surgical time was shorter for the SIM cohort (155 minutes; NO-SIM cohort: 182 minutes; p<0.05). SIM cohort had a better outcome in numeric rating scale (NRS) back at 6 months follow-up when compared to NO-SIM cohort (p<0.05). Preoperative simulation reduced radiation exposure and resulted in less back pain at the 6 months follow-up time point. Preoperative simulation provided guidance in determining the correct cage height. Outcome controls enabled the surgeon to improve the procedure and the software algorithm. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. An Event-Driven Hybrid Molecular Dynamics and Direct Simulation Monte Carlo Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Donev, A; Garcia, A L; Alder, B J

    2007-07-30

    A novel algorithm is developed for the simulation of polymer chains suspended in a solvent. The polymers are represented as chains of hard spheres tethered by square wells and interact with the solvent particles with hard core potentials. The algorithm uses event-driven molecular dynamics (MD) for the simulation of the polymer chain and the interactions between the chain beads and the surrounding solvent particles. The interactions between the solvent particles themselves are not treated deterministically as in event-driven algorithms, rather, the momentum and energy exchange in the solvent is determined stochastically using the Direct Simulation Monte Carlo (DSMC) method. The coupling between the solvent and the solute is consistently represented at the particle level, however, unlike full MD simulations of both the solvent and the solute, the spatial structure of the solvent is ignored. The algorithm is described in detail and applied to the study of the dynamics of a polymer chain tethered to a hard wall subjected to uniform shear. The algorithm closely reproduces full MD simulations with two orders of magnitude greater efficiency. Results do not confirm the existence of periodic (cycling) motion of the polymer chain.

  11. Hybrid Simulations and Scaling Laws for Shock Formation in the UCLA Collisionless Shock Experiment

    Science.gov (United States)

    Larson, David; Winske, Dan; Cowee, Misa; Clark, S. Eric; Niemann, Christoph; Brecht, Stephen

    2015-11-01

    Two- and three-dimensional simulations are used to compare and contrast the plasma expansion, formation of a magnetic cavity, and generation of an outgoing shock wave for conditions relevant to the laser experiment at UCLA, as a function of the background ion mass. A model of the shock formation process is constructed that yields an expression for the speed of the shock, which we show is in good agreement with the simulations. In addition, the criteria for generating strongly-coupled shocks are derived and simulations are used to examine the velocity scaling obtained via momentum conservation. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by DTRA10027-6759.

  12. The discrete multi-hybrid system for the simulation of solid-liquid flows.

    Directory of Open Access Journals (Sweden)

    Alessio Alexiadis

    Full Text Available This study proposes a model based on the combination of Smoothed Particle Hydrodynamics, Coarse Grained Molecular Dynamics and the Discrete Element Method for the simulation of dispersed solid-liquid flows. The model can deal with a large variety of particle types (non-spherical, elastic, breakable, melting, solidifying, swelling, flow conditions (confined, free-surface, microscopic, and scales (from microns to meters. Various examples, ranging from biological fluids to lava flows, are simulated and discussed. In all cases, the model captures the most important features of the flow.

  13. 并行遗传/模拟退火混合算法及其应用%Parallel Genetic Algorithm / Simulated Annealing Hybrid Algorithm and its Applications

    Institute of Scientific and Technical Information of China (English)

    温平川; 徐晓东; 何先刚

    2003-01-01

    This paper presents a highly hybrid Genetic Algorithm / Simulated Annealing algorithm. This algorithmhas been successfully implemented on Beowulf PCs Cluster and applied to a set of standard function optimization prob-lems. From experimental results, it is easily to see that this algorithm proposed by us is not only effective but also robust.

  14. Simulating light-weight Personalised Recommender Systems in Learning Networks: A case for Pedagogy-Oriented and Rating-based Hybrid Recommendation Strategies

    NARCIS (Netherlands)

    Nadolski, Rob; Van den Berg, Bert; Berlanga, Adriana; Drachsler, Hendrik; Hummel, Hans; Koper, Rob; Sloep, Peter

    2008-01-01

    Nadolski, R. J., Van den Berg, B., Berlanga, A. J., Drachsler, H., Hummel, H. G. K., Koper, R., & Sloep, P. B. (2009). Simulating Light-Weight Personalised Recommender Systems in Learning Networks: A Case for Pedagogy-Oriented and Rating-Based Hybrid Recommendation Strategies. Journal of Artificial

  15. Efficient magnetohydrodynamic simulations on distributed multi-GPU systems using a novel GPU Direct-MPI hybrid approach

    Science.gov (United States)

    Wong, Un-Hong; Aoki, Takayuki; Wong, Hon-Cheng

    2014-07-01

    Modern graphics processing units (GPUs) have been widely utilized in magnetohydrodynamic (MHD) simulations in recent years. Due to the limited memory of a single GPU, distributed multi-GPU systems are needed to be explored for large-scale MHD simulations. However, the data transfer between GPUs bottlenecks the efficiency of the simulations on such systems. In this paper we propose a novel GPU Direct-MPI hybrid approach to address this problem for overall performance enhancement. Our approach consists of two strategies: (1) We exploit GPU Direct 2.0 to speedup the data transfers between multiple GPUs in a single node and reduce the total number of message passing interface (MPI) communications; (2) We design Compute Unified Device Architecture (CUDA) kernels instead of using memory copy to speedup the fragmented data exchange in the three-dimensional (3D) decomposition. 3D decomposition is usually not preferable for distributed multi-GPU systems due to its low efficiency of the fragmented data exchange. Our approach has made a breakthrough to make 3D decomposition available on distributed multi-GPU systems. As a result, it can reduce the memory usage and computation time of each partition of the computational domain. Experiment results show twice the FLOPS comparing to common 2D decomposition MPI-only implementation method. The proposed approach has been developed in an efficient implementation for MHD simulations on distributed multi-GPU systems, called MGPU-MHD code. The code realizes the GPU parallelization of a total variation diminishing (TVD) algorithm for solving the multidimensional ideal MHD equations, extending our work from single GPU computation (Wong et al., 2011) to multiple GPUs. Numerical tests and performance measurements are conducted on the TSUBAME 2.0 supercomputer at the Tokyo Institute of Technology. Our code achieves 2 TFLOPS in double precision for the problem with 12003 grid points using 216 GPUs.

  16. Hybrid Simulation of Laser-Plasma Interactions and Fast Electron Transport in Inhomogeneous Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, B I; Kemp, A; Divol, L

    2009-05-27

    A new framework is introduced for kinetic simulation of laser-plasma interactions in an inhomogenous plasma motivated by the goal of performing integrated kinetic simulations of fast-ignition laser fusion. The algorithm addresses the propagation and absorption of an intense electromagnetic wave in an ionized plasma leading to the generation and transport of an energetic electron component. The energetic electrons propagate farther into the plasma to much higher densities where Coulomb collisions become important. The high-density plasma supports an energetic electron current, return currents, self-consistent electric fields associated with maintaining quasi-neutrality, and self-consistent magnetic fields due to the currents. Collisions of the electrons and ions are calculated accurately to track the energetic electrons and model their interactions with the background plasma. Up to a density well above critical density, where the laser electromagnetic field is evanescent, Maxwell's equations are solved with a conventional particle-based, finite-difference scheme. In the higher-density plasma, Maxwell's equations are solved using an Ohm's law neglecting the inertia of the background electrons with the option of omitting the displacement current in Ampere's law. Particle equations of motion with binary collisions are solved for all electrons and ions throughout the system using weighted particles to resolve the density gradient efficiently. The algorithm is analyzed and demonstrated in simulation examples. The simulation scheme introduced here achieves significantly improved efficiencies.

  17. Supporting conceptual product design by hybrid simulation of use processes with scenario structures

    NARCIS (Netherlands)

    Van der Vegte, W.F.; Horváth, I.

    2007-01-01

    The approach described in this paper aims to offer designers a new way to investigate use processes of products by integrating scenarios of expected user behaviour with simulations of physical artefact behaviour. Use is considered a key process in the life cycle of a product, being the phase in

  18. Supporting conceptual product design by hybrid simulation of use processes with scenario structures

    NARCIS (Netherlands)

    Van der Vegte, W.F.; Horváth, I.

    2007-01-01

    The approach described in this paper aims to offer designers a new way to investigate use processes of products by integrating scenarios of expected user behaviour with simulations of physical artefact behaviour. Use is considered a key process in the life cycle of a product, being the phase in whic

  19. Simulation of external flows using a hybrid particle mesh vortex method

    DEFF Research Database (Denmark)

    Spietz, Henrik; Hejlesen, Mads Mølholm; Walther, Jens Honore

    The long-term goal of this project is to develop and apply state-of-the-art simulation software to enable accurate prediction of fluid structure interaction, specifically vortex-induced-vibration and flutter of long-span suspension bridges to avoid error-prone structural designs. In the following...

  20. A State Event Detection Algorithm for Numerically Simulating Hybrid Systems with Model Singularities

    Science.gov (United States)

    2007-01-01

    introduced there as well. However, in these early works as well as in Hay and Griffin [1979], Joglekar and Reklaitis [1984], and Prestin and Berzine...1995. Nonlinear Control Systems. Springer, London. Joglekar, G. and Reklaitis , G. 1984. A simulator for batch and semi-continuous processes