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1

DEVELOPMENT OF THE ADVANCED UTILITY SIMULATION MODEL  

EPA Science Inventory

The paper discusses the development of the Advanced Utility Simulation Model (AUSM), developed for the National Acid Precipitation Assessment Program (NAPAP), to forecast air emissions of pollutants from electric utilities. USM integrates generating unit engineering detail with d...

2

Center for Advanced Modeling and Simulation Intern  

ScienceCinema

Some interns just copy papers and seal envelopes. Not at INL! Check out how Vanessa Gertman, an INL intern working at the Center for Advanced Modeling and Simulation, spent her summer working with some intense visualization software. Lots more content like this is available at INL's facebook page http://www.facebook.com/idahonationallaboratory.

Gertman, Vanessa

2013-05-28

3

Center for Advanced Modeling and Simulation Intern  

SciTech Connect

Some interns just copy papers and seal envelopes. Not at INL! Check out how Vanessa Gertman, an INL intern working at the Center for Advanced Modeling and Simulation, spent her summer working with some intense visualization software. Lots more content like this is available at INL's facebook page http://www.facebook.com/idahonationallaboratory.

Gertman, Vanessa

2010-01-01

4

Advancing Material Models for Automotive Forming Simulations  

SciTech Connect

Simulations in automotive industry need more advanced material models to achieve highly reliable forming and springback predictions. Conventional material models implemented in the FEM-simulation models are not capable to describe the plastic material behaviour during monotonic strain paths with sufficient accuracy. Recently, ESI and Corus co-operate on the implementation of an advanced material model in the FEM-code PAMSTAMP 2G. This applies to the strain hardening model, the influence of strain rate, and the description of the yield locus in these models. A subsequent challenge is the description of the material after a change of strain path.The use of advanced high strength steels in the automotive industry requires a description of plastic material behaviour of multiphase steels. The simplest variant is dual phase steel consisting of a ferritic and a martensitic phase. Multiphase materials also contain a bainitic phase in addition to the ferritic and martensitic phase. More physical descriptions of strain hardening than simple fitted Ludwik/Nadai curves are necessary.Methods to predict plastic behaviour of single-phase materials use a simple dislocation interaction model based on the formed cells structures only. At Corus, a new method is proposed to predict plastic behaviour of multiphase materials have to take hard phases into account, which deform less easily. The resulting deformation gradients create geometrically necessary dislocations. Additional micro-structural information such as morphology and size of hard phase particles or grains is necessary to derive the strain hardening models for this type of materials.Measurements available from the Numisheet benchmarks allow these models to be validated. At Corus, additional measured values are available from cross-die tests. This laboratory test can attain critical deformations by large variations in blank size and processing conditions. The tests are a powerful tool in optimising forming simulations prior to larger scale industrial validation.

Vegter, H.; An, Y.; Horn, C.H.L.J. ten; Atzema, E.H.; Roelofsen, M.E. [Corus Research Development and Technology, PO Box 10000, 1970 CA IJmuiden (Netherlands)

2005-08-05

5

Advanced Modeling, Simulation and Analysis (AMSA) Capability Roadmap Progress Review  

NASA Technical Reports Server (NTRS)

Contents include the following: NASA capability roadmap activity. Advanced modeling, simulation, and analysis overview. Scientific modeling and simulation. Operations modeling. Multi-special sensing (UV-gamma). System integration. M and S Environments and Infrastructure.

Antonsson, Erik; Gombosi, Tamas

2005-01-01

6

ADVANCED UTILITY SIMULATION MODEL, MODEL OPERATIONS (VERSION 1.0)  

EPA Science Inventory

The report is one of several in a series describing the initial development--by the Universities Research Group on Energy (URGE)--of the Advanced Utility Simulation Model (AUSM), one of four stationary source emission and control cost forecasting models developed by the U.S. EPA ...

7

Advanced in turbulence physics and modeling by direct numerical simulations  

NASA Technical Reports Server (NTRS)

The advent of direct numerical simulations of turbulence has opened avenues for research on turbulence physics and turbulence modeling. Direct numerical simulation provides values for anything that the scientist or modeler would like to know about the flow. An overview of some recent advances in the physical understanding of turbulence and in turbulence modeling obtained through such simulations is presented.

Reynolds, W. C.

1987-01-01

8

Advanced Chemical Modeling for Turbulent Combustion Simulations.  

National Technical Information Service (NTIS)

The goals of this project were the development of new sub-filter models for large eddy simulation of turbulent combustion and of chemical mechanisms for jet fuel surrogates. The sub-filter modeling work focuses on the development of a framework for descri...

H. Pitsch

2012-01-01

9

Advances in modeling and simulation of vacuum electronic devices  

Microsoft Academic Search

Recent advances in the modeling and simulation of vacuum electronic devices are reviewed. Design of these devices makes use of a variety of physical models and numerical code types. Progress in the development of these models and codes is outlined and illustrated with specific examples. The state of the art in device simulation is evolving to the point such that

THOMAS M. ANTONSEN; ALFRED A. MONDELLI; BARUCH LEVUSH; JOHN P. VERBONCOEUR; C. K. Birdsall

1999-01-01

10

Gasification CFD Modeling for Advanced Power Plant Simulations  

SciTech Connect

In this paper we have described recent progress on developing CFD models for two commercial-scale gasifiers, including a two-stage, coal slurry-fed, oxygen-blown, pressurized, entrained-flow gasifier and a scaled-up design of the PSDF transport gasifier. Also highlighted was NETL’s Advanced Process Engineering Co-Simulator for coupling high-fidelity equipment models with process simulation for the design, analysis, and optimization of advanced power plants. Using APECS, we have coupled the entrained-flow gasifier CFD model into a coal-fired, gasification-based FutureGen power and hydrogen production plant. The results for the FutureGen co-simulation illustrate how the APECS technology can help engineers better understand and optimize gasifier fluid dynamics and related phenomena that impact overall power plant performance.

Zitney, S.E.; Guenther, C.P.

2005-09-01

11

Advanced modeling and simulation to design and manufacture high performance and reliable advanced microelectronics and microsystems.  

SciTech Connect

An interdisciplinary team of scientists and engineers having broad expertise in materials processing and properties, materials characterization, and computational mechanics was assembled to develop science-based modeling/simulation technology to design and reproducibly manufacture high performance and reliable, complex microelectronics and microsystems. The team's efforts focused on defining and developing a science-based infrastructure to enable predictive compaction, sintering, stress, and thermomechanical modeling in ''real systems'', including: (1) developing techniques to and determining materials properties and constitutive behavior required for modeling; (2) developing new, improved/updated models and modeling capabilities, (3) ensuring that models are representative of the physical phenomena being simulated; and (4) assessing existing modeling capabilities to identify advances necessary to facilitate the practical application of Sandia's predictive modeling technology.

Nettleship, Ian (University of Pittsburgh, Pittsburgh, PA); Hinklin, Thomas; Holcomb, David Joseph; Tandon, Rajan; Arguello, Jose Guadalupe, Jr. (,; .); Dempsey, James Franklin; Ewsuk, Kevin Gregory; Neilsen, Michael K.; Lanagan, Michael (Pennsylvania State University, University Park, PA)

2007-07-01

12

Enabling Advanced Modeling and Simulations for Fuel-Flexible Combustors  

SciTech Connect

The overall goal of the present project is to enable advanced modeling and simulations for the design and optimization of fuel-flexible turbine combustors. For this purpose we use a high-fidelity, extensively-tested large-eddy simulation (LES) code and state-of-the-art models for premixed/partially-premixed turbulent combustion developed in the PI's group. In the frame of the present project, these techniques are applied, assessed, and improved for hydrogen enriched premixed and partially premixed gas-turbine combustion. Our innovative approaches include a completely consistent description of flame propagation, a coupled progress variable/level set method to resolve the detailed flame structure, and incorporation of thermal-diffusion (non-unity Lewis number) effects. In addition, we have developed a general flamelet-type transformation holding in the limits of both non-premixed and premixed burning. As a result, a model for partially premixed combustion has been derived. The coupled progress variable/level method and the general flamelet tranformation were validated by LES of a lean-premixed low-swirl burner that has been studied experimentally at Lawrence Berkeley National Laboratory. The model is extended to include the non-unity Lewis number effects, which play a critical role in fuel-flexible combustor with high hydrogen content fuel. More specifically, a two-scalar model for lean hydrogen and hydrogen-enriched combustion is developed and validated against experimental and direct numerical simulation (DNS) data. Results are presented to emphasize the importance of non-unity Lewis number effects in the lean-premixed low-swirl burner of interest in this project. The proposed model gives improved results, which shows that the inclusion of the non-unity Lewis number effects is essential for accurate prediction of the lean-premixed low-swirl flame.

Heinz Pitsch

2010-05-31

13

Enabling Advanced Modeling and Simulations for Fuel-Flexible Combustors  

SciTech Connect

The overall goal of the present project is to enable advanced modeling and simulations for the design and optimization of fuel-flexible turbine combustors. For this purpose we use a high fidelity, extensively-tested large-eddy simulation (LES) code and state-of-the-art models for premixed/partially-premixed turbulent combustion developed in the PI's group. In the frame of the present project, these techniques are applied, assessed, and improved for hydrogen enriched premixed and partially premixed gas-turbine combustion. Our innovative approaches include a completely consistent description of flame propagation; a coupled progress variable/level set method to resolve the detailed flame structure, and incorporation of thermal-diffusion (non-unity Lewis number) effects. In addition, we have developed a general flamelet-type transformation holding in the limits of both non-premixed and premixed burning. As a result, a model for partially premixed combustion has been derived. The coupled progress variable/level method and the general flamelet transformation were validated by LES of a lean-premixed low-swirl burner that has been studied experimentally at Lawrence Berkeley National Laboratory. The model is extended to include the non-unity Lewis number effects, which play a critical role in fuel-flexible combustor with high hydrogen content fuel. More specifically, a two-scalar model for lean hydrogen and hydrogen-enriched combustion is developed and validated against experimental and direct numerical simulation (DNS) data. Results are presented to emphasize the importance of non-unity Lewis number effects in the lean-premixed low-swirl burner of interest in this project. The proposed model gives improved results, which shows that the inclusion of the non-unity Lewis number effects is essential for accurate prediction of the lean-premixed low-swirl flame.

Pitsch, Heinz

2010-05-31

14

An advanced supply chain management tool based on modeling and simulation  

Microsoft Academic Search

The paper presents an advanced modeling approach and a simulation model for supporting supply chain management. The first objective is to develop a flexible, time-efficient and parametric supply chain simulator starting from a discrete event simulation package. To this end we propose and advanced modeling approach. The second objective is to provide a decision making tool for supply chain management.

Francesco Longo; Giovanni Mirabelli

2008-01-01

15

ADVANCED TECHNIQUES FOR RESERVOIR SIMULATION AND MODELING OF NONCONVENTIONAL WELLS  

SciTech Connect

Nonconventional wells, which include horizontal, deviated, multilateral and ''smart'' wells, offer great potential for the efficient management of oil and gas reservoirs. These wells are able to contact larger regions of the reservoir than conventional wells and can also be used to target isolated hydrocarbon accumulations. The use of nonconventional wells instrumented with downhole inflow control devices allows for even greater flexibility in production. Because nonconventional wells can be very expensive to drill, complete and instrument, it is important to be able to optimize their deployment, which requires the accurate prediction of their performance. However, predictions of nonconventional well performance are often inaccurate. This is likely due to inadequacies in some of the reservoir engineering and reservoir simulation tools used to model and optimize nonconventional well performance. A number of new issues arise in the modeling and optimization of nonconventional wells. For example, the optimal use of downhole inflow control devices has not been addressed for practical problems. In addition, the impact of geological and engineering uncertainty (e.g., valve reliability) has not been previously considered. In order to model and optimize nonconventional wells in different settings, it is essential that the tools be implemented into a general reservoir simulator. This simulator must be sufficiently general and robust and must in addition be linked to a sophisticated well model. Our research under this five year project addressed all of the key areas indicated above. The overall project was divided into three main categories: (1) advanced reservoir simulation techniques for modeling nonconventional wells; (2) improved techniques for computing well productivity (for use in reservoir engineering calculations) and for coupling the well to the simulator (which includes the accurate calculation of well index and the modeling of multiphase flow in the wellbore); and (3) accurate approaches to account for the effects of reservoir heterogeneity and for the optimization of nonconventional well deployment. An overview of our progress in each of these main areas is as follows. A general purpose object-oriented research simulator (GPRS) was developed under this project. The GPRS code is managed using modern software management techniques and has been deployed to many companies and research institutions. The simulator includes general black-oil and compositional modeling modules. The formulation is general in that it allows for the selection of a wide variety of primary and secondary variables and accommodates varying degrees of solution implicitness. Specifically, we developed and implemented an IMPSAT procedure (implicit in pressure and saturation, explicit in all other variables) for compositional modeling as well as an adaptive implicit procedure. Both of these capabilities allow for efficiency gains through selective implicitness. The code treats cell connections through a general connection list, which allows it to accommodate both structured and unstructured grids. The GPRS code was written to be easily extendable so new modeling techniques can be readily incorporated. Along these lines, we developed a new dual porosity module compatible with the GPRS framework, as well as a new discrete fracture model applicable for fractured or faulted reservoirs. Both of these methods display substantial advantages over previous implementations. Further, we assessed the performance of different preconditioners in an attempt to improve the efficiency of the linear solver. As a result of this investigation, substantial improvements in solver performance were achieved.

Louis J. Durlofsky; Khalid Aziz

2004-08-20

16

Integration of the WRF Model into the Advanced Climate Modeling and Environmental Simulations Program  

Microsoft Academic Search

The Advanced Climate Modeling and Environmental Simulations program (ACMES) was developed to provide quality modeled data that can be used to generate summarized regional climate statistics at times and locations for which climatological values based on observations are not directly available. The ACMES modeling strategy uses a mesocale numerical weather prediction (NWP) model to produce gridded data fields for any

K. W. Schulz; G. Van Knowe; M. Alonso; K. Waight

2005-01-01

17

Model Validation of The 1997 Jeep Cherokee For the National Advanced Driving Simulator  

Microsoft Academic Search

This paper presents an evaluation of a complete vehicle dynamics model for a 1997 Jeep Cherokee to be used for the National Advanced Driving Simulator. Vehicle handling and powertrain dynamics are evaluated and simulation results are compared with experimental field- testing. NADSdyna, the National Advanced Driving Simulator vehicle dynamics software, is used. The Jeep evaluation covers vehicle directional dynamics that

M. Kamel Salaani

18

The Advanced Logistics System CYBER 73: A Simulation Model.  

National Technical Information Service (NTIS)

In support of a request from the Air Force Logistics Command, a model of the Advanced Logistics System (ALS) CYBER 73 Batch processing system was developed. The initial specification required that this model allow changes to the magnetic tape unit configu...

W. J. Blitt R. Heidenreich

1975-01-01

19

Advanced 3D Photocathode Modeling and Simulations Final Report  

SciTech Connect

High brightness electron beams required by the proposed Next Linear Collider demand strong advances in photocathode electron gun performance. Significant improvement in the production of such beams with rf photocathode electron guns is hampered by the lack high-fidelity simulations. The critical missing piece in existing gun codes is a physics-based, detailed treatment of the very complex and highly nonlinear photoemission process.

Dimitre A Dimitrov; David L Bruhwiler

2005-06-06

20

Development of Advanced Models for 3D Photocathode PIC Simulations  

Microsoft Academic Search

Codes for simulating photocathode electron guns invariably assume the emission of an idealized electron distribution from the cathode, regardless of the particular particle emission model that is implemented. The output of such simulations, a relatively clean and smooth distribution with very little variation as a function of the azimuthal angle, is inconsistent with the highly irregular and asymmetric electron bunches

D. A. Dimitrov; D. L. Bruhwiler; J. R. Cary; P. Messmer; P. Stoltz; Kevin L. Jensen; Donald W. Feldman; P. G. O'Shea

2005-01-01

21

ADVANCED UTILITY SIMULATION MODEL ANALYTICAL DOCUMENTATION STATE LEVEL MODEL (VERSION 1.0)  

EPA Science Inventory

The report is one of 11 in a series describing the initial development of the Advanced Utility Simulation Model (AUSM). The AUSM is one of four stationary source emission and control cost forecasting models developed by EPA for the National Acid Precipitation Assessment Program (...

22

ADVANCED UTILITY SIMULATION MODEL, PROGRAM DOCUMENTATION. STATE LEVEL MODEL (VERSION 1.0)  

EPA Science Inventory

The report is one of 11 in a series describing the initial development of the Advanced Utility Simulation Model (AUSM). The AUSM is one of four stationary source emission and control cost forecasting models developed by EPA for the National Acid Precipitation Assessment Program (...

23

Recent Advances in Underwater Acoustic Modelling and Simulation  

NASA Astrophysics Data System (ADS)

A comprehensive review of international developments in underwater acoustic modelling is used to construct an updated technology baseline containing 107 propagation models, 16 noise models, 17 reverberation models and 25 sonar performance models. This updated technology baseline represents a 30% increase over a previous baseline published in 1996. When executed in higher-level simulations, these models can generate predictive and diagnostic outputs that are useful to acoustical oceanographers or sonar technologists in the analysis of complex systems operating in the undersea environment. Recent modelling developments described in the technical literature suggest two principal areas of application: low-frequency, inverse acoustics in deep water; and high-frequency, bottom-interacting acoustics in coastal regions. Rapid changes in global geopolitics have opened new avenues for collaboration, thereby facilitating the transfer of modelling and simulation technologies among members of the international community. This accelerated technology transfer has created new imperatives for international standards in modelling and simulation architectures. National and international activities to promote interoperability among modelling and simulation efforts in government, industry and academia are reviewed and discussed.

ETTER, P. C.

2001-02-01

24

Advanced dispatcher training simulator  

Microsoft Academic Search

This article analyzes the modeling and describes the algorithmic breakthroughs and the use of parallel processing in power system dispatcher training simulation. The first industrial version of the FAST-DTS simulator (running a 400 node, 80 generator power system), with its advanced instructor and operator stations, is described and illustrated with various training scenarios. Principles used for the configuration and the

S. Gissinger; P. Chaumes; J.-P. Antoine; A. Bihain; M. Stubbe

2000-01-01

25

ADVANCED UTILITY SIMULATION MODEL DOCUMENTATION OF SYSTEM DESIGN STATE LEVEL MODEL (VERSION 1.0)  

EPA Science Inventory

The report is one of 11 in a series describing the initial development of the Advanced Utility Simulation Model (AUSM) by the Universities Research Group on Energy (URGE) and its continued development by the Science Applications International Corporation (SAIC) research team. The...

26

Advanced modelling of failure mechanisms in aluminium sheet forming simulation  

Microsoft Academic Search

In this paper novel and efficient approaches to model localized necking and ductile fracture in sheet forming simulation using\\u000a the finite element method are presented. The stress-based forming limit curve is used to detect localized necking. Post-necking\\u000a is captured using a new concept called accelerated plastic thinning. A simple ductile fracture model was developed. Various\\u000a application examples demonstrate the capabilities

Holger Aretz; Stefan Keller; Rolf Vogt; Olaf Engler

2009-01-01

27

Advanced Techniques for Reservoir Simulation and Modeling of Non-Conventional Wells  

SciTech Connect

This project targets the development of (1) advanced reservoir simulation techniques for modeling non-conventional wells; (2) improved techniques for computing well productivity (for use in reservoir engineering calculations) and well index (for use in simulation models), including the effects of wellbore flow; and (3) accurate approaches to account for heterogeneity in the near-well region.

Durlofsky, Louis J.

2000-08-28

28

Advanced Modeling and Simulation to Design and Manufacture High Performance and Reliable Advanced Microelectronics and Microsystems.  

National Technical Information Service (NTIS)

An interdisciplinary team of scientists and engineers having broad expertise in materials processing and properties, materials characterization, and computational mechanics was assembled to develop science-based modeling/simulation technology to design an...

J. G. Arguello K. G. Ewsuk M. Neilsen R. Tandon T. Hinklin

2007-01-01

29

ADVANCED UTILITY SIMULATION MODEL, ENERGY AND EMPLOYMENT IMPACTS MODULE (VERSION 1.0)  

EPA Science Inventory

The report is one of an 11-volume series that describes the initial development of the Advanced Utility Simulation Model (AUSM), one of four stationary source emission and control cost forecasting models developed in 1984 for the National Acid Precipitation Assessment Program (NA...

30

National Advanced Driving Simulator  

NSDL National Science Digital Library

The National Advanced Driving Simulator (NADS) is housed at the University of Iowa and is associated with the National Highway Traffic Safety Administration. Visitors to the NADS Website can see a slideshow overview of the facility, read about the experimental program, and view simulations (QuickTime). Multi-body dynamics, software engineering, tire soil, simulation technology, and electrical engineering are some of the topics discussed at the NADS site. Data on mass, moment of inertia, and center of mass for vehicles ranging from a station wagon to a Hummer can be viewed via the Vehicle Models page (.pdf). This is a cool site for taking a glimpse at the latest in automotive engineering and computer simulation technologies.

31

ADVANCED UTILITY SIMULATION MODEL, DESCRIPTION OF THE NATIONAL LOOP (VERSION 3.0)  

EPA Science Inventory

The report is one of 11 in a series describing the initial development of the Advanced Utility Simulation Model (AUSM) by the Universities Research Group on Energy (URGE) and its continued development by the Science Applications International Corporation (SAIC) research team. The...

32

ADVANCED UTILITY SIMULATION MODEL, DATA BASE MAINTENANCE (VERSION 1.0)  

EPA Science Inventory

The report is one of 11 in a series describing the initial development of the Advanced Utility Simulation Model (AUSM) by the Universities Research Group on Energy (URGE) and its continued development by the Science Applications International Corporation (SAIC) research team. The...

33

The Advanced Modeling, Simulation and Analysis Capability Roadmap Vision for Engineering  

NASA Technical Reports Server (NTRS)

This paper summarizes a subset of the Advanced Modeling Simulation and Analysis (AMSA) Capability Roadmap that was developed for NASA in 2005. The AMSA Capability Roadmap Team was chartered to "To identify what is needed to enhance NASA's capabilities to produce leading-edge exploration and science missions by improving engineering system development, operations, and science understanding through broad application of advanced modeling, simulation and analysis techniques." The AMSA roadmap stressed the need for integration, not just within the science, engineering and operations domains themselves, but also across these domains. Here we discuss the roadmap element pertaining to integration within the engineering domain, with a particular focus on implications for future observatory missions. The AMSA products supporting the system engineering function are mission information, bounds on information quality, and system validation guidance. The Engineering roadmap element contains 5 sub-elements: (1) Large-Scale Systems Models, (2) Anomalous Behavior Models, (3) advanced Uncertainty Models, (4) Virtual Testing Models, and (5) space-based Robotics Manufacture and Servicing Models.

Zang, Thomas; Lieber, Mike; Norton, Charles; Fucik, Karen

2006-01-01

34

RECENT ADVANCES ON THE SIMULATION MODELS FOR AD HOC NETWORKS: REAL TRAFFIC AND MOBILITY MODELS  

Microsoft Academic Search

In order to provide credible and valid simulation results it is important to built simulation models that accurately represent the environments were ad hoc networks will be deployed. Recent research results have shown that there is a disparity of 30% between protocol performance in real test beds and the one in simulation environments. In this paper we summarize the recent

ARTA DOCI; LEONARD BAROLLI; FATOS XHAFA

35

TCAD simulation vs. experimental results in FDSOI technology: From advanced mobility modeling to 6T-SRAM cell characteristics prediction  

Microsoft Academic Search

We present TCAD simulations based on advanced mobility modeling including Surface Roughness (SR) and Remote Coulomb Scattering (RCS) effects, quantum correction and short channel effects. From these calibrated models, FDSOI 6T-SRAM cells are simulated and compared to experimental data. The very good agreement achieved between simulations and electrical data on both mobility and electrical figures of merit (device and SRAM)

Marie-Anne Jaud; Pascal Scheiblin; Sébastien Martinie; Mikaël Cassé; Olivier Rozeau; Julien Dura; Jérôme Mazurier; Alain Toffoli; Olivier Thomas; François Andrieu; Olivier Weber

2010-01-01

36

Advanced process engineering co-simulation using CFD-based reduced order models  

SciTech Connect

The process and energy industries face the challenge of designing the next generation of plants to operate with unprecedented efficiency and near-zero emissions, while performing profitably amid fluctuations in costs for raw materials, finished products, and energy. To achieve these targets, the designers of future plants are increasingly relying upon modeling and simulation to create virtual plants that allow them to evaluate design concepts without the expense of pilot-scale and demonstration facilities. Two of the more commonly used simulation tools include process simulators for describing the entire plant as a network of simplified equipment models and computational fluid dynamic (CFD) packages for modeling an isolated equipment item in great detail by accounting for complex thermal and fluid flow phenomena. The Advanced Process Engineering Co-Simulator (APECS) sponsored by the U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) has been developed to combine process simulation software with CFD-based equipment simulation software so that design engineers can analyze and optimize the coupled fluid flow, heat and mass transfer, and chemical reactions that drive overall plant performance (Zitney et al., 2006). The process/CFD software integration was accomplished using the process-industry standard CAPE-OPEN interfaces.

Lang, Y.-D.; Biegler, L.T.; Munteanu, S.; Madsen, J.I.; Zitney, S.E.

2007-11-04

37

ADVANCED UTILITY SIMULATION MODEL, REPORT OF SENSITIVITY TESTING, CALIBRATION, AND MODEL OUTPUT COMPARISONS (VERSION 3.0) TAPE  

EPA Science Inventory

The report is one of 11 in a series describing the initial development of the Advanced Utility Simulation Model (AUSM) by the Universities Research Group on Energy (URGE) and its continued development by the Science Applications International Corporation (SAIC) research team. The...

38

Advanced computers and simulation  

SciTech Connect

Accelerator physicists today have access to computers that are far more powerful than those available just 10 years ago. In the early 1980's, desktop workstations performed less one million floating point operations per second (Mflops), and the realized performance of vector supercomputers was at best a few hundred Mflops. Today vector processing is available on the desktop, providing researchers with performance approaching 100 Mflops at a price that is measured in thousands of dollars. Furthermore, advances in Massively Parallel Processors (MPP) have made performance of over 10 gigaflops a reality, and around mid-decade MPPs are expected to be capable of teraflops performance. Along with advances in MPP hardware, researchers have also made significant progress in developing algorithms and software for MPPS. These changes have had, and will continue to have, a significant impact on the work of computational accelerator physicists. Now, instead of running particle simulations with just a few thousand particles, we can perform desktop simulations with tens of thousands of simulation particles, and calculations with well over 1 million particles are being performed on MPPs. In the area of computational electromagnetics, simulations that used to be performed only on vector supercomputers now run in several hours on desktop workstations, and researchers are hoping to perform simulations with over one billion mesh points on future MPPs. In this paper we will discuss the latest advances, and what can be expected in the near future, in hardware, software and applications codes for advanced simulation of particle accelerators.

Ryne, R.D.

1993-01-01

39

Advanced computers and simulation  

SciTech Connect

Accelerator physicists today have access to computers that are far more powerful than those available just 10 years ago. In the early 1980`s, desktop workstations performed less one million floating point operations per second (Mflops), and the realized performance of vector supercomputers was at best a few hundred Mflops. Today vector processing is available on the desktop, providing researchers with performance approaching 100 Mflops at a price that is measured in thousands of dollars. Furthermore, advances in Massively Parallel Processors (MPP) have made performance of over 10 gigaflops a reality, and around mid-decade MPPs are expected to be capable of teraflops performance. Along with advances in MPP hardware, researchers have also made significant progress in developing algorithms and software for MPPS. These changes have had, and will continue to have, a significant impact on the work of computational accelerator physicists. Now, instead of running particle simulations with just a few thousand particles, we can perform desktop simulations with tens of thousands of simulation particles, and calculations with well over 1 million particles are being performed on MPPs. In the area of computational electromagnetics, simulations that used to be performed only on vector supercomputers now run in several hours on desktop workstations, and researchers are hoping to perform simulations with over one billion mesh points on future MPPs. In this paper we will discuss the latest advances, and what can be expected in the near future, in hardware, software and applications codes for advanced simulation of particle accelerators.

Ryne, R.D.

1993-06-01

40

Modeling and Simulation of an M1 Abrams Tank with Advanced Track Dynamics and Integrated Virtual Diesel Engine  

Microsoft Academic Search

New capabilities for simulating a tracked vehicle are presented, including an advanced dynamic track model, a high-fidelity diesel engine system model, and an integration scheme to perform a coupled simulation of vehicle\\/powertrain dynamics. These capabilities are essential for understanding the interplay of vehicle dynamics and powertrain dynamics, including track vibration (and durability). Suspension response and engine performance. The dynamic track

Dennis N. Assanis; Walter Bryzik; Matthew P. Castanier; Ian M. Darnell; Zoran S. Filipi; Gregory M. Hulbert; Dohoy Jung; Zheng-Dong Ma; Noel C. Perkins; Christophe Pierre; Craig M. Scholar; Yongsheng Wang; Guoqing Zhang

1999-01-01

41

Numerical modeling of brine discharge: commercial models, MEDVSA online simulation tools and advanced computational fluid dynamics  

Microsoft Academic Search

Numerical modeling is a prediction tool useful for the design of brine discharge configurations and for environmental impact assessments, to prevent the potential impacts of brine in marine environments. Among the existing approaches of governing equations, dimensional analysis formulas and integration models are usually applied to brine discharge simulations, as is the case of the most used commercial tools for

P. Palomar; J. L. Lara; I. J. Losada; L. Tarrade

2012-01-01

42

Recent advances in semi-analytical scattering models for NDT simulation  

NASA Astrophysics Data System (ADS)

For several years, CEA-LIST and partners have been developing ultrasonic simulation tools with the aim of modelling non-destructive evaluation. The existing ultrasonic modules allow us to simulate fully real ultrasonic inspection scenarios in a range of applications which requires the computation of the propagated beam, as well as its interaction with flaws. To fulfil requirements of an intensive use (for parametric studies), the choice has been made to adopt mainly analytical approximate or exact methods to model the scattering of ultrasound by flaws. The applied analytical theories (Kirchhoff and Born approximations, GTD, SOV...) were already described in previous GDR communication. Over the years, this "semi-analytical" approach has been enriched by adaptations and improvements of the existing models or by new models, in order to extend the applicability of the simulation tools. This paper is devoted to the following recent advances performed in the framework of this approach: The SOV method based on the exact analytical model for the scattering from a cylindrical cavity has been extended in 3D to account for field variations along the cylinder. This new 3D model leads to an improvement in simulation of small side-drilled holes. Concerning the geometrical theories of diffraction (GTD), subroutines for calculation of the 2D wedge diffraction coefficients (for bulk or Rayleigh incident waves) have been developed by the Waves and Fields Group and uniform corrections (UAT and UTD) are under investigation. Modelling of the contribution of the head wave and creeping wave to the echoes arising from a wedge. Numerous experimental validations of the developed models are provided. New possibilities offered by these new developments are emphasized.

Darmon, M.; Chatillon, S.; Mahaut, S.; Calmon, P.; Fradkin, L. J.; Zernov, V.

2011-01-01

43

Strategic Plan for Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)  

SciTech Connect

The Nuclear Energy Computational Fluid Dynamics Advanced Modeling and Simulation (NE-CAMS) system is being developed at the Idaho National Laboratory (INL) in collaboration with Bettis Laboratory, Sandia National Laboratory (SNL), Argonne National Laboratory (ANL), Utah State University (USU), and other interested parties with the objective of developing and implementing a comprehensive and readily accessible data and information management system for computational fluid dynamics (CFD) verification and validation (V&V) in support of nuclear energy systems design and safety analysis. The two key objectives of the NE-CAMS effort are to identify, collect, assess, store and maintain high resolution and high quality experimental data and related expert knowledge (metadata) for use in CFD V&V assessments specific to the nuclear energy field and to establish a working relationship with the U.S. Nuclear Regulatory Commission (NRC) to develop a CFD V&V database, including benchmark cases, that addresses and supports the associated NRC regulations and policies on the use of CFD analysis. In particular, the NE-CAMS system will support the Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Program, which aims to develop and deploy advanced modeling and simulation methods and computational tools for reliable numerical simulation of nuclear reactor systems for design and safety analysis. Primary NE-CAMS Elements There are four primary elements of the NE-CAMS knowledge base designed to support computer modeling and simulation in the nuclear energy arena as listed below. Element 1. The database will contain experimental data that can be used for CFD validation that is relevant to nuclear reactor and plant processes, particularly those important to the nuclear industry and the NRC. Element 2. Qualification standards for data evaluation and classification will be incorporated and applied such that validation data sets will result in well-defined, well-characterized data. Element 3. Standards will be established for the design and operation of experiments for the generation of new validation data sets that are to be submitted to NE-CAMS that addresses the completeness and characterization of the dataset. Element 4. Standards will be developed for performing verification and validation (V&V) to establish confidence levels in CFD analyses of nuclear reactor processes; such processes will be acceptable and recognized by both CFD experts and the NRC.

Kimberlyn C. Mousseau

2011-10-01

44

An educational training simulator for advanced perfusion techniques using a high-fidelity virtual patient model.  

PubMed

The operation of cardiopulmonary bypass procedure requires an advanced skill in both physiological and mechanical knowledge. We developed a virtual patient simulator system using a numerical cardiovascular regulation model to manage perfusion crisis. This article evaluates the ability of the new simulator to prevent perfusion crisis. It combined short-term baroreflex regulation of venous capacity, vascular resistance, heart rate, time-varying elastance of the heart, and plasma-refilling with a simple lumped parameter model of the cardiovascular system. The combination of parameters related to baroreflex regulation was calculated using clinical hemodynamic data. We examined the effect of differences in autonomous-nerve control parameter settings on changes in blood volume and hemodynamic parameters and determined the influence of the model on operation of the control arterial line flow and blood volume during the initiation and weaning from cardiopulmonary bypass. Typical blood pressure (BP) changes (hypertension, stable, and hypotension) were reproducible using a combination of four control parameters that can be estimated from changes in patient physiology, BP, and blood volume. This simulation model is a useful educational tool to learn the recognition and management skills of extracorporeal circulation. Identification method for control parameter can be applied for diagnosis of heart failure. PMID:22963152

Tokaji, Megumi; Ninomiya, Shinji; Kurosaki, Tatsuya; Orihashi, Kazumasa; Sueda, Taijiro

2012-12-01

45

Simulating carbon exchange using a regional atmospheric model coupled to an advanced land-surface model  

NASA Astrophysics Data System (ADS)

A large scale mismatch exists between our understanding and quantification of ecosystem atmosphere exchange of carbon dioxide at local scale and continental scales. This paper will focus on the carbon exchange on the regional scale to address the following question: What are the main controlling factors determining atmospheric carbon dioxide content at a regional scale? We use the Regional Atmospheric Modelling System (RAMS), coupled with a land surface scheme simulating carbon, heat and momentum fluxes (SWAPS-C), and including also sub models for urban and marine fluxes, which in principle include the main controlling mechanisms and capture the relevant dynamics of the system. To validate the model, observations are used which were taken during an intensive observational campaign in the central Netherlands in summer 2002. These included flux-site observations, vertical profiles at tall towers and spatial fluxes of various variables taken by aircraft. The coupled regional model (RAMS-SWAPS-C) generally does a good job in simulating results close to reality. The validation of the model demonstrates that surface fluxes of heat, water and CO2 are reasonably well simulated. The comparison against aircraft data shows that the regional meteorology is captured by the model. Comparing spatially explicit simulated and observed fluxes we conclude that in general simulated latent heat fluxes are underestimated by the model to the observations which exhibit large standard deviation for all flights. Sensitivity experiments demonstrated the relevance of the urban emissions of carbon dioxide for the carbon balance in this particular region. The same test also show the relation between uncertainties in surface fluxes and those in atmospheric concentrations.

Ter Maat, H. W.; Hutjes, R. W. A.

2008-10-01

46

Ductile damage prediction in metal forming processes: Advanced modeling and numerical simulation  

NASA Astrophysics Data System (ADS)

This paper describes the needs required in modern virtual metal forming including both sheet and bulk metal forming of mechanical components. These concern the advanced modeling of thermo-mechanical behavior including the multiphysical phenomena and their interaction or strong coupling, as well as the associated numerical aspects using fully adaptive simulation strategies. First a survey of advanced constitutive equations accounting for the main thermomechanical phenomena as the thermo-elasto-plastic finite strains with isotropic and kinematic hardenings fully coupled with ductile damage will be presented. Only the macroscopic phenomenological approach with state variables (monoscale approach) will be discussed in the general framework of the rational thermodynamics for generalized micromorphic continua. The micro-macro (multi-scales approach) in the framework of polycrystalline inelasticity is not presented here for the sake of shortness but will be presented during the oral presentation. The main numerical aspects related to the resolution of the associated initial and boundary value problem will be outlined. A fully adaptive numerical methodology will be briefly described and some numerical examples will be given in order to show the high predictive capabilities of this adaptive methodology for virtual metal forming simulations.

Saanouni, K.

2013-05-01

47

Strategic Plan for Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)  

SciTech Connect

NE-KAMS knowledge base will assist computational analysts, physics model developers, experimentalists, nuclear reactor designers, and federal regulators by: (1) Establishing accepted standards, requirements and best practices for V&V and UQ of computational models and simulations, (2) Establishing accepted standards and procedures for qualifying and classifying experimental and numerical benchmark data, (3) Providing readily accessible databases for nuclear energy related experimental and numerical benchmark data that can be used in V&V assessments and computational methods development, (4) Providing a searchable knowledge base of information, documents and data on V&V and UQ, and (5) Providing web-enabled applications, tools and utilities for V&V and UQ activities, data assessment and processing, and information and data searches. From its inception, NE-KAMS will directly support nuclear energy research, development and demonstration programs within the U.S. Department of Energy (DOE), including the Consortium for Advanced Simulation of Light Water Reactors (CASL), the Nuclear Energy Advanced Modeling and Simulation (NEAMS), the Light Water Reactor Sustainability (LWRS), the Small Modular Reactors (SMR), and the Next Generation Nuclear Power Plant (NGNP) programs. These programs all involve computational modeling and simulation (M&S) of nuclear reactor systems, components and processes, and it is envisioned that NE-KAMS will help to coordinate and facilitate collaboration and sharing of resources and expertise for V&V and UQ across these programs. In addition, from the outset, NE-KAMS will support the use of computational M&S in the nuclear industry by developing guidelines and recommended practices aimed at quantifying the uncertainty and assessing the applicability of existing analysis models and methods. The NE-KAMS effort will initially focus on supporting the use of computational fluid dynamics (CFD) and thermal hydraulics (T/H) analysis for M&S of nuclear reactor systems, components and processes, and will later expand to include materials, fuel system performance and other areas of M&S as time and funding allow.

Rich Johnson; Kimberlyn C. Mousseau; Hyung Lee

2011-09-01

48

Propulsion Simulations Using Advanced Turbulence Models with the Unstructured Grid CFD Tool, TetrUSS  

NASA Technical Reports Server (NTRS)

A computational investigation has been completed to assess the capability of TetrUSS for exhaust nozzle flows. Three configurations were chosen for this study (1) an axisymmetric supersonic jet, (2) a transonic axisymmetric boattail with solid sting operated at different Reynolds number and Mach number, and (3) an isolated non-axisymmetric nacelle with a supersonic cruise nozzle. These configurations were chosen because existing experimental data provided a means for measuring the ability of TetrUSS for simulating complex nozzle flows. The main objective of this paper is to validate the implementation of advanced two-equation turbulence models in the unstructured-grid CFD code USM3D for propulsion flow cases. USM3D is the flow solver of the TetrUSS system. Three different turbulence models, namely, Menter Shear Stress Transport (SST), basic k epsilon, and the Spalart-Allmaras (SA) are used in the present study. The results are generally in agreement with other implementations of these models in structured-grid CFD codes. Results indicate that USM3D provides accurate simulations for complex aerodynamic configurations with propulsion integration.

Abdol-Hamid, Khaled S.; Frink, Neal T.; Deere, Karen A.; Pandya, Mohangna J.

2004-01-01

49

Do Advanced Material Models Contribute to Accuracy in Industrial Sheet Forming Simulations?  

Microsoft Academic Search

The accuracy of material models can have a large impact on the overall accuracy of material forming simulations in general and sheet forming simulations in particular. For large strain plastic deformations, the material model usually consists of a yield function and a hardening relation, optionally including the influence of temperature and strain rate. In large-scale simulations it is favourable to

Boogaard van den A. H; H. H. Wisselink; J. Huetink

2005-01-01

50

In-Service Design & Performance Prediction of Advanced Fusion Material Systems by Computational Modeling and Simulation  

SciTech Connect

This final report on "In-Service Design & Performance Prediction of Advanced Fusion Material Systems by Computational Modeling and Simulation" (DE-FG03-01ER54632) consists of a series of summaries of work that has been published, or presented at meetings, or both. It briefly describes results on the following topics: 1) A Transport and Fate Model for Helium and Helium Management; 2) Atomistic Studies of Point Defect Energetics, Dynamics and Interactions; 3) Multiscale Modeling of Fracture consisting of: 3a) A Micromechanical Model of the Master Curve (MC) Universal Fracture Toughness-Temperature Curve Relation, KJc(T - To), 3b) An Embrittlement DTo Prediction Model for the Irradiation Hardening Dominated Regime, 3c) Non-hardening Irradiation Assisted Thermal and Helium Embrittlement of 8Cr Tempered Martensitic Steels: Compilation and Analysis of Existing Data, 3d) A Model for the KJc(T) of a High Strength NFA MA957, 3e) Cracked Body Size and Geometry Effects of Measured and Effective Fracture Toughness-Model Based MC and To Evaluations of F82H and Eurofer 97, 3-f) Size and Geometry Effects on the Effective Toughness of Cracked Fusion Structures; 4) Modeling the Multiscale Mechanics of Flow Localization-Ductility Loss in Irradiation Damaged BCC Alloys; and 5) A Universal Relation Between Indentation Hardness and True Stress-Strain Constitutive Behavior. Further details can be found in the cited references or presentations that generally can be accessed on the internet, or provided upon request to the authors. Finally, it is noted that this effort was integrated with our base program in fusion materials, also funded by the DOE OFES.

G. R. Odette; G. E. Lucas

2005-11-15

51

Going Public with Advanced Simulations  

Microsoft Academic Search

\\u000a Web technology provides public access to advanced simulation models and efficiently distributes vast volumes of data in an\\u000a unprecedented way. The traditional boundary between the producers and the users of data has become less distinct. Users now\\u000a download data generated by themselves or by others. The role of the hydrologist has therefore shifted towards the management\\u000a of systems and tools

Niclas Hjerdt; Berit Arheimer; Göran Lindström; Ylva Westman; Esa Falkenroth; Martin Hultman

52

The Nuclear Energy Advanced Modeling and Simulation Safeguards and Separations Reprocessing Plant Toolkit  

SciTech Connect

This report details the progress made in the development of the Reprocessing Plant Toolkit (RPTk) for the DOE Nuclear Energy Advanced Modeling and Simulation (NEAMS) program. RPTk is an ongoing development effort intended to provide users with an extensible, integrated, and scalable software framework for the modeling and simulation of spent nuclear fuel reprocessing plants by enabling the insertion and coupling of user-developed physicochemical modules of variable fidelity. The NEAMS Safeguards and Separations IPSC (SafeSeps) and the Enabling Computational Technologies (ECT) supporting program element have partnered to release an initial version of the RPTk with a focus on software usability and utility. RPTk implements a data flow architecture that is the source of the system's extensibility and scalability. Data flows through physicochemical modules sequentially, with each module importing data, evolving it, and exporting the updated data to the next downstream module. This is accomplished through various architectural abstractions designed to give RPTk true plug-and-play capabilities. A simple application of this architecture, as well as RPTk data flow and evolution, is demonstrated in Section 6 with an application consisting of two coupled physicochemical modules. The remaining sections describe this ongoing work in full, from system vision and design inception to full implementation. Section 3 describes the relevant software development processes used by the RPTk development team. These processes allow the team to manage system complexity and ensure stakeholder satisfaction. This section also details the work done on the RPTk ``black box'' and ``white box'' models, with a special focus on the separation of concerns between the RPTk user interface and application runtime. Section 4 and 5 discuss that application runtime component in more detail, and describe the dependencies, behavior, and rigorous testing of its constituent components.

McCaskey, Alex [ORNL; Billings, Jay Jay [ORNL; de Almeida, Valmor F [ORNL

2011-08-01

53

ADVANCED UTILITY SIMULATION MODEL, MULTI-PERIOD MULTI-STATE MODULE DESIGN DOCUMENTATION (VERSION 1.0)  

EPA Science Inventory

The report is one of 11 in a series describing the initial development of the Advanced Utility Simulation Model (AUSM) by the Universities Research Group on Energy (URGE) and its continued development by the Science Applications International Corporation (SAIC) research team. The...

54

Nuclear Energy Advanced Modelling and Simulation (NEAMS) Waste Integrated Performance and Safety Codes (IPSC): FY10 Development and Integration.  

National Technical Information Service (NTIS)

This report describes the progress in fiscal year 2010 in developing theWaste Integrated Performance and Safety Codes (IPSC) in support of the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign. The ...

D. Sassani G. Freeze H. C. Edwards J. Bouchard J. G. Argiiello L. Criscenti P. A. Schultz T. Dewers

2011-01-01

55

An architecture and model for cognitive engineering simulation analysis - Application to advanced aviation automation  

NASA Technical Reports Server (NTRS)

The process of designing crew stations for large-scale, complex automated systems is made difficult because of the flexibility of roles that the crew can assume, and by the rapid rate at which system designs become fixed. Modern cockpit automation frequently involves multiple layers of control and display technology in which human operators must exercise equipment in augmented, supervisory, and fully automated control modes. In this context, we maintain that effective human-centered design is dependent on adequate models of human/system performance in which representations of the equipment, the human operator(s), and the mission tasks are available to designers for manipulation and modification. The joint Army-NASA Aircrew/Aircraft Integration (A3I) Program, with its attendant Man-machine Integration Design and Analysis System (MIDAS), was initiated to meet this challenge. MIDAS provides designers with a test bed for analyzing human-system integration in an environment in which both cognitive human function and 'intelligent' machine function are described in similar terms. This distributed object-oriented simulation system, its architecture and assumptions, and our experiences from its application in advanced aviation crew stations are described.

Corker, Kevin M.; Smith, Barry R.

1993-01-01

56

Geophysical Simulations Conducted by the SEG Advanced Modeling Project (SEAM) for a Deepwater Subsalt Resource  

NASA Astrophysics Data System (ADS)

Geophysical simulations are playing an increasingly large role in both predicting the future evolution of complex systems and for providing benchmark data to test new analysis approaches. As geophysical inversion schemes for determining model structure become increasingly sophisticated, and their ability to incorporate multiple types of geophysical data increases, there is need for challenging benchmark datasets to be used for testing and validating the schemes. If simulated datasets are to be used to evaluate the robustness and reliability of inversion schemes, the simulations must be conducted on realistic models and some estimate of the reliability of the simulations must be made. We have developed a model that contains a major salt body and a suite of petroleum reservoirs. A suite of geophysical simulations is being conducted on the model. The goal at the start of the SEAM project was to capture as much physics and realism as possible in a 3D model that was relevant to geophysical oil and gas exploration. Certain facets of the model were designed to go beyond the capabilities of current geophysical modeling and imaging technology. The philosophy behind this was that enhanced imaging capabilities would evolve and become available over the 10 or more years of the expected lifetime of the model. An important design goal for the SEAM earth model is internal consistency across the domains of rock properties (e.g. fundamental parameters like Vshale, porosity, and pore fluid type), the intermediate level elastic and electromagnetic parameters, and the output simulations for seismic, electromagnetic and gravity fields. By rooting the ultimate simulation back to the rock properties, any changes in the latter are guaranteed to change all the elastic and other parameters automatically, consistently, and with the appropriate correlations. A model founded on rock properties provides a test bed not just for the inversion of seismic data for reflectivity, but also for the inversion of one or a combination of seismic, gravity, EM or reflectivity data for reservoir properties. Thus it challenges not just processors, tomographers and imagers, but also the reservoir characterization and monitoring interests. The development of an approach for evaluating the quality of all numerical simulations over a complex model requires the development of a set of tools for validating the simulations. Our goals have been to understand the limitations of numerical simulations on a model with the type of complexity of the SEAM model and to ensure that the simulations produced during the project met acceptable standards for reliability. This has been achieved through the specification of rigorous standards for the simulations and the validation of resulting simulations against a well-calibrated benchmark code. Ongoing work includes the simulation of Controlled Source Electromagnetic, magnetotelluric, elastic and acoustic anisotropic simulations that will complement the existing set of acoustic simulations that we have already been completed.

Fehler, M. C.

2010-12-01

57

Testing Dynamic Simulations Models for Different Types of Advanced Pumped Storage Hydro Units.  

National Technical Information Service (NTIS)

This report is one of several reports developed during the U.S. Department of Energy (DOE) study on the Modeling and Analysis of Value of Advanced Pumped Storage Hydropower in the United States. The study was led by Argonne National Laboratory in collabor...

B. Gong J. Feltes P. Donalek V. Gevorgian V. Koritarov Y. Kazachkov

2013-01-01

58

Strategic Plan for Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)  

Microsoft Academic Search

NE-KAMS knowledge base will assist computational analysts, physics model developers, experimentalists, nuclear reactor designers, and federal regulators by: (1) Establishing accepted standards, requirements and best practices for V&V and UQ of computational models and simulations, (2) Establishing accepted standards and procedures for qualifying and classifying experimental and numerical benchmark data, (3) Providing readily accessible databases for nuclear energy related experimental

Rich Johnson; Kimberlyn C. Mousseau; Hyung Lee

2011-01-01

59

Geophysical Simulations Conducted by the SEG Advanced Modeling Project (SEAM) for a Deepwater Subsalt Resource  

Microsoft Academic Search

Geophysical simulations are playing an increasingly large role in both predicting the future evolution of complex systems and for providing benchmark data to test new analysis approaches. As geophysical inversion schemes for determining model structure become increasingly sophisticated, and their ability to incorporate multiple types of geophysical data increases, there is need for challenging benchmark datasets to be used for

M. C. Fehler

2010-01-01

60

An Evaluation of Two Advanced Turbulence Models for Simulating the Flow and Dispersion Around Buildings  

Microsoft Academic Search

We have presented a validation for our model through simulating the flow and dispersion around a cubical building. It was\\u000a found that the LES model yields more accurate results but with roughly an order of magnitude increase in computational cost.\\u000a Several conclusions can be drawn from this study:\\u000a \\u000a \\u000a \\u000a 1. \\u000a Instantaneous snapshots of concentration from the LES model have similar vertical

S. T. Chan; D. E. Stevens

2000-01-01

61

The Consortium for Advanced Simulation of Light Water Reactors  

Microsoft Academic Search

The Consortium for Advanced Simulation of Light Water Reactors (CASL) is a DOE Energy Innovation Hub for modeling and simulation of nuclear reactors. It brings together an exceptionally capable team from national labs, industry and academia that will apply existing modeling and simulation capabilities and develop advanced capabilities to create a usable environment for predictive simulation of light water reactors

Ronaldo Szilard; Hongbin Zhang; Doug Kothe; Paul Turinsky

2011-01-01

62

A Damage Model for the Simulation of Delamination in Advanced Composites under Variable-Mode Loading  

NASA Technical Reports Server (NTRS)

A thermodynamically consistent damage model is proposed for the simulation of progressive delamination in composite materials under variable-mode ratio. The model is formulated in the context of Damage Mechanics. A novel constitutive equation is developed to model the initiation and propagation of delamination. A delamination initiation criterion is proposed to assure that the formulation can account for changes in the loading mode in a thermodynamically consistent way. The formulation accounts for crack closure effects to avoid interfacial penetration of two adjacent layers after complete decohesion. The model is implemented in a finite element formulation, and the numerical predictions are compared with experimental results obtained in both composite test specimens and structural components.

Turon, A.; Camanho, P. P.; Costa, J.; Davila, C. G.

2006-01-01

63

Nuclear Energy Advanced Modeling and Simulation (NEAMS) waste Integrated Performance and Safety Codes (IPSC) : gap analysis for high fidelity and performance assessment code development  

Microsoft Academic Search

This report describes a gap analysis performed in the process of developing the Waste Integrated Performance and Safety Codes (IPSC) in support of the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign. The goal of the Waste IPSC is to develop an integrated suite of computational modeling and simulation capabilities to quantitatively assess

Joon H. Lee; Malcolm Dean Siegel; Arguello Jose Guadalupe Jr; Stephen Walter Webb; Thomas A. Dewers; Paul E. Mariner; Harold Carter Edwards; Timothy J. Fuller; Geoffrey A. Freeze; Carlos F. Jove-Colon; Yifeng Wang

2011-01-01

64

[Advances in researches on thorax mechanical modeling and simulation during cardiopulmonary resuscitation].  

PubMed

Cardiopulmonary resuscitation (CPR) is vital for cardio arrest victims; in this field, researches have been aiming at its mechanism, operation guidelines, new CPR machines and so on. This paper summarized the studies on the mechanical characteristics of the thorax under CPR, and on the simulation work of sternal-displacement relationship in CPR manikins. The data from modeling work showed that the thorax's sternal-displacement relationship could be graphically represented by a hysteresis curve. As the actual CPR manikins' mechanical structures of the thorax are too simplified, it is necessary to do the work of improvement. PMID:19634697

Xie, Xinwu; Sun, Qiuming; Ni, Aijuan; Tian, Feng

2009-06-01

65

Advancing predictive models for particulate formation in turbulent flames via massively parallel direct numerical simulations.  

PubMed

Combustion of fossil fuels is likely to continue for the near future due to the growing trends in energy consumption worldwide. The increase in efficiency and the reduction of pollutant emissions from combustion devices are pivotal to achieving meaningful levels of carbon abatement as part of the ongoing climate change efforts. Computational fluid dynamics featuring adequate combustion models will play an increasingly important role in the design of more efficient and cleaner industrial burners, internal combustion engines, and combustors for stationary power generation and aircraft propulsion. Today, turbulent combustion modelling is hindered severely by the lack of data that are accurate and sufficiently complete to assess and remedy model deficiencies effectively. In particular, the formation of pollutants is a complex, nonlinear and multi-scale process characterized by the interaction of molecular and turbulent mixing with a multitude of chemical reactions with disparate time scales. The use of direct numerical simulation (DNS) featuring a state of the art description of the underlying chemistry and physical processes has contributed greatly to combustion model development in recent years. In this paper, the analysis of the intricate evolution of soot formation in turbulent flames demonstrates how DNS databases are used to illuminate relevant physico-chemical mechanisms and to identify modelling needs. PMID:25024412

Bisetti, Fabrizio; Attili, Antonio; Pitsch, Heinz

2014-08-13

66

Advances in the simulation of toroidal gyro Landau fluid model turbulence  

SciTech Connect

The gyro-Landau fluid (GLF) model equations for toroidal geometry have been recently applied to the study ion temperature gradient (ITG) mode turbulence using the 3D nonlinear ballooning mode representation (BMR). The present paper extends this work by treating some unresolved issues conceming ITG turbulence with adiabatic electrons. Although eddies are highly elongated in the radial direction long time radial correlation lengths are short and comparable to poloidal lengths. Although transport at vanishing shear is not particularly large, transport at reverse global shear, is significantly less. Electrostatic transport at moderate shear is not much effected by inclusion of local shear and average favorable curvature. Transport is suppressed when critical E{times}B rotational shear is comparable to the maximum linear growth rate with only a weak dependence on magnetic shear. Self consistent turbulent transport of toroidal momentum can result in a transport bifurcation at suffciently large r/(Rq). However the main thrust of the new formulation in the paper deals with advances in the development of finite beta GLF models with trapped electron and BMR numerical methods for treating the fast parallel field motion of the untrapped electrons.

Waltz, R.E. [General Atomics, San Diego, CA (United States); Kerbel, G.D.; Milovich, J. [Lawrence Livermore National Lab., CA (United States); Hammett, G.W. [Princeton Univ., NJ (United States). Plasma Physics Lab.

1994-12-01

67

High Level Requirements for the Nuclear Energy -- Knowledge Base for Advanced Modeling and Simulation (NE-KAMS)  

SciTech Connect

The US Department of Energy, Office of Nuclear Energy (DOE-NE), has been tasked with the important mission of ensuring that nuclear energy remains a compelling and viable energy source in the U.S. The motivations behind this mission include cost-effectively meeting the expected increases in the power needs of the country, reducing carbon emissions and reducing dependence on foreign energy sources. In the near term, to ensure that nuclear power remains a key element of U.S. energy strategy and portfolio, the DOE-NE will be working with the nuclear industry to support safe and efficient operations of existing nuclear power plants. In the long term, to meet the increasing energy needs of the U.S., the DOE-NE will be investing in research and development (R&D) and working in concert with the nuclear industry to build and deploy new, safer and more efficient nuclear power plants. The safe and efficient operations of existing nuclear power plants and designing, licensing and deploying new reactor designs, however, will require focused R&D programs as well as the extensive use and leveraging of advanced modeling and simulation (M&S). M&S will play a key role in ensuring safe and efficient operations of existing and new nuclear reactors. The DOE-NE has been actively developing and promoting the use of advanced M&S in reactor design and analysis through its R&D programs, e.g., the Nuclear Energy Advanced Modeling and Simulation (NEAMS) and Consortium for Advanced Simulation of Light Water Reactors (CASL) programs. Also, nuclear reactor vendors are already using CFD and CSM, for design, analysis, and licensing. However, these M&S tools cannot be used with confidence for nuclear reactor applications unless accompanied and supported by verification and validation (V&V) and uncertainty quantification (UQ) processes and procedures which provide quantitative measures of uncertainty for specific applications. The Nuclear Energy Knowledge base for Advanced Modeling and Simulation (NE-KAMS) is being developed at the Idaho National Laboratory in conjunction with Bettis Laboratory, Sandia National Laboratories, Argonne National Laboratory, Utah State University and others with the objective of establishing a comprehensive and web-accessible knowledge base that will provide technical services and resources for V&V and UQ of M&S in nuclear energy sciences and engineering. The knowledge base will serve as an important resource for technical exchange and collaboration that will enable credible and reliable computational models and simulations for application to nuclear reactor design, analysis and licensing. NE-KAMS will serve as a valuable resource for the nuclear industry, academia, the national laboratories, the U.S. Nuclear Regulatory Commission (NRC) and the public and will help ensure the safe, economical and reliable operation of existing and future nuclear reactors. From its inception, NE-KAMS will directly support nuclear energy research, development and demonstration programs within the U.S. Department of Energy (DOE), including the CASL, NEAMS, Light Water Reactor Sustainability (LWRS), Small Modular Reactors (SMR), and Next Generation Nuclear Power Plant (NGNP) programs. These programs all involve M&S of nuclear reactor systems, components and processes, and it is envisioned that NE-KAMS will help to coordinate and facilitate collaboration and sharing of resources and expertise for V&V and UQ across these programs.

Rich Johnson; Hyung Lee; Kimberlyn C. Mousseau

2011-09-01

68

Nuclear Energy Advanced Modeling and Simulation (NEAMS) Waste Integrated Performance and Safety Codes (IPSC) : FY10 development and integration.  

SciTech Connect

This report describes the progress in fiscal year 2010 in developing the Waste Integrated Performance and Safety Codes (IPSC) in support of the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign. The goal of the Waste IPSC is to develop an integrated suite of computational modeling and simulation capabilities to quantitatively assess the long-term performance of waste forms in the engineered and geologic environments of a radioactive waste storage or disposal system. The Waste IPSC will provide this simulation capability (1) for a range of disposal concepts, waste form types, engineered repository designs, and geologic settings, (2) for a range of time scales and distances, (3) with appropriate consideration of the inherent uncertainties, and (4) in accordance with robust verification, validation, and software quality requirements. Waste IPSC activities in fiscal year 2010 focused on specifying a challenge problem to demonstrate proof of concept, developing a verification and validation plan, and performing an initial gap analyses to identify candidate codes and tools to support the development and integration of the Waste IPSC. The current Waste IPSC strategy is to acquire and integrate the necessary Waste IPSC capabilities wherever feasible, and develop only those capabilities that cannot be acquired or suitably integrated, verified, or validated. This year-end progress report documents the FY10 status of acquisition, development, and integration of thermal-hydrologic-chemical-mechanical (THCM) code capabilities, frameworks, and enabling tools and infrastructure.

Criscenti, Louise Jacqueline; Sassani, David Carl; Arguello, Jose Guadalupe, Jr.; Dewers, Thomas A.; Bouchard, Julie F.; Edwards, Harold Carter; Freeze, Geoffrey A.; Wang, Yifeng; Schultz, Peter Andrew

2011-02-01

69

Advances in Supply Chain Simulation  

Microsoft Academic Search

The lecture aims to provide an insight into modern approaches to simulation-based analysis of supply chains. It gives an overview of using modeling and simulation (M&S) for facing different types of activities in supply chain management. In particular, different issues are considered, starting with new criticality such as: green logistics; supply chain resilience; sustainable logistics; logistics security; logistics safety; logistics

Agostino G. Bruzzone; Yuri Merkuryev

2009-01-01

70

Leveraging data analytics, patterning simulations and metrology models to enhance CD metrology accuracy for advanced IC nodes  

NASA Astrophysics Data System (ADS)

Integrated Circuit (IC) technology is changing in multiple ways: 193i to EUV exposure, planar to non-planar device architecture, from single exposure lithography to multiple exposure and DSA patterning etc. Critical dimension (CD) control requirement is becoming stringent and more exhaustive: CD and process window are shrinking., three sigma CD control of < 2 nm is required in complex geometries, and metrology uncertainty of < 0.2 nm is required to achieve the target CD control for advanced IC nodes (e.g. 14 nm, 10 nm and 7 nm nodes). There are fundamental capability and accuracy limits in all the metrology techniques that are detrimental to the success of advanced IC nodes. Reference or physical CD metrology is provided by CD-AFM, and TEM while workhorse metrology is provided by CD-SEM, Scatterometry, Model Based Infrared Reflectrometry (MBIR). Precision alone is not sufficient moving forward. No single technique is sufficient to ensure the required accuracy of patterning. The accuracy of CD-AFM is ~1 nm and precision in TEM is poor due to limited statistics. CD-SEM, scatterometry and MBIR need to be calibrated by reference measurements for ensuring the accuracy of patterned CDs and patterning models. There is a dire need of measurement with < 0.5 nm accuracy and the industry currently does not have that capability with inline measurments. Being aware of the capability gaps for various metrology techniques, we have employed data processing techniques and predictive data analytics, along with patterning simulation and metrology models, and data integration techniques to selected applications demonstrating the potential solution and practicality of such an approach to enhance CD metrology accuracy. Data from multiple metrology techniques has been analyzed in multiple ways to extract information with associated uncertainties and integrated to extract the useful and more accurate CD and profile information of the structures. This paper presents the optimization of scatterometry and MBIR model calibration and feasibility to extrapolate not only in design and process space but from one process step to a previous process step. Well calibrated scatterometry model or patterning simulation model can be used to accurately extrapolate and interpolate in the design and process space for lithography patterning where AFM is not capable to accurately measure sub-40 nm trenches. Uncertainty associated with extrapolation can be large and needs to be minimized. We have made use of measurements from CD-SEM and CD-AFM, along with the patterning and scatterometry simulation models to estimate the uncertainty associated with extrapolation and methods to reduce it. First time we have reported the application of machine learning (Artificial Neural Networks) to the resist shrinkage systematic phenomenon to accurately predict the preshrink CD based on supervised learning using the CD-AFM data. The study lays out various basic concepts, approaches and protocols of multiple source data processing and integration for hybrid metrology approach. Impacts of this study include more accurate metrology, patterning models and better process controls for advanced IC nodes.

Rana, Narender; Zhang, Yunlin; Kagalwala, Taher; Hu, Lin; Bailey, Todd

2014-04-01

71

ADVANCED URBANIZED METEOROLOGICAL MODELING AND AIR QUALITY SIMULATIONS WITH CMAQ AT NEIGHBORHOOD SCALES  

EPA Science Inventory

We present results from a study testing the new boundary layer parameterization method, the canopy drag approach (DA) which is designed to explicitly simulate the effects of buildings, street and tree canopies on the dynamic, thermodynamic structure and dispersion fields in urban...

72

Advanced Spectral Modeling Development.  

National Technical Information Service (NTIS)

This report describes the results of a basic research program to develop advanced spectral modeling techniques to treat a variety of current topics in spectroscopy and radiative transfer relevant to the modeling of atmospheric transmission and radiance fi...

R. G. Isaacs R. D. Worsham W. O. Gallery S. A. Clough J. L. Moncet

1992-01-01

73

Applying advanced system simulation techniques to INFOSEC system development  

Microsoft Academic Search

The gate-level system simulation (GLSS) methodology, developed under the demonstration of avionics module exchangeability via simulation (DAMES) program, allows integration of gate-level models to create simulatable system models that reflect actual hardware designs. The virtual integrated systems (VIS) approach expands GLSS to include the use of behavioral models, and allows system software to be developed and debugged. Advanced simulation capabilities

V. P. Calandra; P. Leahy

1990-01-01

74

Modeling of medium voltage power electronics converters utilizing advanced simulation tools  

Microsoft Academic Search

This paper addresses the steady-state and dynamic modeling of a three-level, neutral-point-clamped (NPC) voltage source converter (VSC) with active front-end (AFE) in a commercial 2.5 MW variable speed motor drive (VSD). The AFE of the modeled VSD adopts the selective harmonic elimination SHE-PWM technique with the optimization of inverter power capacity and power source quality for a wide- range VSD

Oleg Vodyakho; Tim Chiocchio; Michael Steurer; Chris Edrington; Mike Sloderbeck

2011-01-01

75

WARPM Framework for advanced plasma model simulations on many-core architectures  

NASA Astrophysics Data System (ADS)

A new framework WARPM designed for many-core computing architectures such as GPU is presented. The framework supports both multi-fluid and continuum kinetic plasma models. We provide exemplary physics results including whistler wave propagation, and show performance gains. For good performance on many-core architectures, code design should minimize data movement. The algorithms developed are thus both local and explicit. Fluid and continuum kinetic models on structured grids also benefit from predictable data access patterns as opposed to PIC models. The resulting framework is a hybrid combination of MPI for communication between nodes, threads for task parallelism on each node, and OpenCL parallel numerical method implementation across hundreds of cores per node. The framework manages data movement, sub-domain sequencing, and I/O intelligently such that memory bandwidth bottlenecks can be significantly hidden. Use of OpenCL and our method for sequencing computation naturally allows for heterogeneous computation utilizing both CPU and GPU on a node. A new dynamic OpenCL code assembly scheme allows support for many different models, numerical methods, and geometries; a specific combination of these is chosen at runtime then used to generate a single compiled kernel.

Reddell, Noah; Shumlak, Uri

2012-10-01

76

Nuclear Energy Advanced Modeling and Simulation (NEAMS) Waste Integrated Performance and Safety Codes (IPSC): Gap Analysis for High Fidelity and Performance Assessment Code Development.  

National Technical Information Service (NTIS)

This report describes a gap analysis performed in the process of developing the Waste Integrated Performance and Safety Codes (IPSC) in support of the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campai...

C. Jove-Colon G. Freeze H. C. Edwards J. G. Arguello J. H. Lee M. Siegel P. Mariner S. Webb T. Dewers T. J. Fuller Y. Wang

2011-01-01

77

HiSIM: a drift-diffusion-based advanced MOSFET model for circuit simulation with easy parameter extraction  

Microsoft Academic Search

We present here the MOSFET model HiSIM (Hiroshima University Starc IGFET model). As HiSIM employs the drift-diffusion approximation and preserves correct modeling of the surface potential in the channel, it is not only accurate, but additionally, model parameter number is small, parameter interdependence is removed, and parameter extraction becomes easy. Measured current-voltage characteristics of advanced MOSFETs are thus reproduced with

M. Suetake; K. Suematsu; H. Nagakura; M. Miura-Mattausch; H. J. Mattausch; S. Kumashiro; T. Yamaguchi; S. Odanakaa; N. Nakayama

2000-01-01

78

Advanced Initiatives in Medical Simulation, 3rd Annual Conference to Create Awareness of Medical Simulation.  

National Technical Information Service (NTIS)

This report summarizes the presentations at the 3rd Annual Advanced Initiatives in Medical Simulation Conference. The conference title was 'Simulation in Health Care: A Model for Improving Patient Safety and Ensuring Quality.' The presentations were as fo...

J. Eder-Van Hook

2006-01-01

79

Improved Low-cloud Simulation from the Community Atmosphere Model with an Advanced Third-order Turbulence Closure  

NASA Astrophysics Data System (ADS)

This presentation describes the implementation and testing of an advanced third-order turbulence closure, an intermediately-prognostic higher-order turbulence closure (IPHOC), into the Community Atmosphere Model version 5 (CAM5). The third-order turbulence closure introduces a joint double-Gaussian distribution of liquid water potential temperature, total water mixing ratio, and vertical velocity to represent the subgrid scale variations including skewed turbulence circulations. The distribution is inferred from the first-, second-, and third-order moments of the variables given above and is used to diagnose cloud fraction and grid-mean liquid water mixing ratio, as well as the buoyancy term and fourth-order terms in the equations describing the evolution of the second- and third-order moments. In addition, a diagnostic planetary boundary layer (PBL) height approach has been incorporated in IPHOC in order to resolve the strong inversion above PBL for the coarse general circulation model (GCM) vertical grid-spacing. The IPHOC replaces PBL, shallow convection, and cloud macrophysics parameterizations in CAM5. The coupling of CAM5 with IPHOC (CAM5-IP) represents a more unified treatment of boundary layer and shallow convective processes. Results from global climate simulations are presented and suggest that CAM5-IP can provide a better treatment of boundary layer clouds and processes when compared to CAM5. The global annual mean low cloud fraction and precipitation are compared among CAM5, CAM5-IP, and a multi-scale modeling framework model with IPHOC (MMF-IP). The low cloud amounts near the west coast of the subtropical continents are well produced in CAM5-IP and are more abundant than in other two models. The global mean liquid water path is the closest to the SSM/I observation. The cloud structures from CAM5-IP, represented by the cloud fraction and cloud water content at 15°S transect, compare well with the CloudSat/CALIPSO observations. The shallow cumulus clouds from the standard CAM5 are shallower and have less liquid, while those from MMF-IP are deeper and have more liquid than from the CloudSat/CALIPSO observations. Interpretations of these results will be provided at the meeting.

Cheng, A.; Xu, K.

2013-12-01

80

Advanced friction modeling for sheet metal forming  

Microsoft Academic Search

The Coulomb friction model is frequently used for sheet metal forming simulations. This model incorporates a constant coefficient of friction and does not take the influence of important parameters such as contact pressure or deformation of the sheet material into account. This article presents a more advanced friction model for large-scale forming simulations based on the surface changes on the

J. Hol; M. V. Cid Alfaro; M. B. de Rooij; T. Meinders

2011-01-01

81

14 CFR Appendix H to Part 121 - Advanced Simulation  

Code of Federal Regulations, 2010 CFR

...conducted under an advanced simulation training program approved...training program. The advanced simulation training program must include...the operator's advanced simulation training program, or changes...simulator controls (including environmental and trouble panels),...

2010-01-01

82

14 CFR Appendix H to Part 121 - Advanced Simulation  

Code of Federal Regulations, 2010 CFR

...conducted under an advanced simulation training program approved...training program. The advanced simulation training program must include...the operator's advanced simulation training program, or changes...simulator controls (including environmental and trouble panels),...

2009-01-01

83

Development of an Advanced Simulator to Model Mobility Control and Geomechanics during CO{sub 2} Floods  

SciTech Connect

The simulator is an isothermal, three-dimensional, four-phase, compositional, equation-of– state (EOS) simulator. We have named the simulator UTDOE-CO2 capable of simulating various recovery processes (i.e., primary, secondary waterflooding, and miscible and immiscible gas flooding). We include both the Peng-Robinson EOS and the Redlich-Kwong EOS models. A Gibbs stability test is also included in the model to perform a phase identification test to consistently label each phase for subsequent property calculations such as relative permeability, viscosity, density, interfacial tension, and capillary pressure. Our time step strategy is based on an IMPEC-type method (implicit pressure and explicit concentration). The gridblock pressure is solved first using the explicit dating of saturation-dependent terms. Subsequently, the material balance equations are solved explicitly for the total concentration of each component. The physical dispersion term is also included in the governing equations. The simulator includes (1) several foam model(s) for gas mobility control, (2) compositional relative permeability models with the hysteresis option, (3) corner point grid and several efficient solvers, (4) geomechanics module to compute stress field as the result of CO{sub 2} injection/production, (5) the format of commercial visualization software, S3graf from Science-soft Ltd., was implemented for user friendly visualization of the simulation results. All tasks are completed and the simulator was fully tested and delivered to the DOE office including a user’s guide and several input files and the executable for Windows Pcs. We have published several SPE papers, presented several posters, and one MS thesis is completed (V. Pudugramam, 2013) resulting from this DOE funded project.

Delshad, Mojdeh; Wheeler, Mary; Sepehrnoori, Kamy; Pope, Gary

2013-12-31

84

Simulator design for advanced ISDN satellite design and experiments  

NASA Technical Reports Server (NTRS)

This simulation design task completion report documents the simulation techniques associated with the network models of both the Interim Service ISDN (integrated services digital network) Satellite (ISIS) and the Full Service ISDN Satellite (FSIS) architectures. The ISIS network model design represents satellite systems like the Advanced Communication Technology Satellite (ACTS) orbiting switch. The FSIS architecture, the ultimate aim of this element of the Satellite Communications Applications Research (SCAR) program, moves all control and switching functions on-board the next generation ISDN communication satellite. The technical and operational parameters for the advanced ISDN communications satellite design will be obtained from the simulation of ISIS and FSIS engineering software models for their major subsystems. Discrete events simulation experiments will be performed with these models using various traffic scenarios, design parameters and operational procedures. The data from these simulations will be used to determine the engineering parameters for the advanced ISDN communications satellite.

Pepin, Gerald R.

1992-01-01

85

ELMy H-mode linear simulation with 3-field model on experimental advanced superconducting tokamak using BOUT++  

SciTech Connect

H-mode plasmas with ELM (edge localized mode) have been realized on experimental advanced superconducting tokamak (EAST) with 2.45 GHz low hybrid wave at P{sub LHW}{approx}1 MW in 2010. Data from EAST experiments including magnetic geometry, measured pressure profiles, and calculated current profiles are used to investigate the physics of ELM utilizing the BOUT++ code. Results from linear simulations show that the ELMs in EAST are dominated by resistive ballooning modes. When the Lundquist number (dimensionless ratio of the resistive diffusion time to the Alfven time) is equal to or less than 10{sup 7}, the resistive ballooning modes are found to become unstable in the ELMy H-mode plasma. For a fixed pedestal pressure profile, increasing plasma current generates more activities of low-n ELMs.

Liu, Z. X.; Gao, X.; Liu, S. C.; Ding, S. Y.; Li, J. G. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Xia, T. Y. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Xu, X. Q. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Hughes, J. W. [Massachusetts Institute of Technology, Plasma Science and Fusion Center, 175 Albany Street, Cambridge, Massachusetts 02139 (United States)

2012-10-15

86

ELMy H-mode linear simulation with 3-field model on experimental advanced superconducting tokamak using BOUT++  

NASA Astrophysics Data System (ADS)

H-mode plasmas with ELM (edge localized mode) have been realized on experimental advanced superconducting tokamak (EAST) with 2.45 GHz low hybrid wave at PLHW~1 MW in 2010. Data from EAST experiments including magnetic geometry, measured pressure profiles, and calculated current profiles are used to investigate the physics of ELM utilizing the BOUT++ code. Results from linear simulations show that the ELMs in EAST are dominated by resistive ballooning modes. When the Lundquist number (dimensionless ratio of the resistive diffusion time to the Alfvén time) is equal to or less than 107, the resistive ballooning modes are found to become unstable in the ELMy H-mode plasma. For a fixed pedestal pressure profile, increasing plasma current generates more activities of low-n ELMs.

Liu, Z. X.; Xia, T. Y.; Xu, X. Q.; Gao, X.; Hughes, J. W.; Liu, S. C.; Ding, S. Y.; Li, J. G.

2012-10-01

87

Advances in Machining Process Modeling  

NASA Astrophysics Data System (ADS)

Ever increasing speed and affordability of computing resources together with the advances in the modeling techniques made it possible to use the numerical models like finite element method (FEM), to simulate the metal cutting processes numerically. This paper explains the recent technological advances made in the commercial DEFORM™ system to facilitate the modeling of metal cutting process. During the first phase of this work a 2D system has been developed which assumes orthogonal cutting conditions. The second phase of this work has resulted in the development of a modeling system for 3D machining processes with main focus on turning. The modeling tools developed in this project utilize a hybrid procedure including both transient and steady state approaches. Automated remeshing procedure is being used with great success. Multiple coating layers on the insert can be modeled to study their thermal effects. Elastic and thermal response of the insert during the machining process can also be modeled using this system. The Usui's wear model has also been implemented in the system to study the tool wear. The system developed has been validated with various results reported from actual cutting tests and comparisons are found to be reasonably accurate.

Chigurupati, Pavanachand; Jinn, Jong-Tae; Oh, Jin Young; Yin, Yanling; Zhang, Hua; Wu, Wei-Tsu

2004-06-01

88

Role of Effects-based Metrics in Advancing R&D Agility through Modelling and Simulation Based Exercises  

Microsoft Academic Search

While modelling and simulation technologies have been applied across the breadth and depth of military applications, such as concept development and experimentation, system and force structure design, training and operational decision-support, the perceived value of M&S technologies has seemingly focused on traditional measures of cost-effectiveness associated primarily with the consequence of early decisions on downstream lifecycle cost avoidance. The lack

C. Pogue; A. L. Vallerand; J. Pagotto; S. Lam

89

Advanced Implementation of Hybrid Simulation.  

National Technical Information Service (NTIS)

Time-stepping integration methods that act as the computational drivers during a hybrid simulation and that need to be provided by or implemented in the finite element analysis software are thoroughly investigated. Integration schemes from both the class ...

A. H. Schellenberg G. L. Fenves S. A. Mahin

2009-01-01

90

ADVANCED CAPABILITIES FOR GAS TURBINE ENGINE PERFORMANCE SIMULATIONS  

Microsoft Academic Search

This paper describes the integration of advanced methods such as component zooming and distributed computing, in an object-oriented simulation environment dedicated to gas turbine engine performance modelling. A 1-D compressor stage stacking method is used to demonstrate three approaches for integrating numerical zooming in an engine model. In the first approach a 1-D compressor model produces a compressor map that

A. Alexiou; E. H. Baalbergen; O. Kogenhop; K. Mathioudakis; P. Arendsen

2007-01-01

91

Development of advanced materials for spallation neutron sources and radiation damage simulation based on multi-scale models  

NASA Astrophysics Data System (ADS)

This report describes the status review of the JSPS Grant Team to develop advanced materials for the spallation neutron sources and modeling of radiation damage. One of the advanced materials is a toughness enhanced, fine-grained tungsten material (W-TiC) having four-times larger fracture toughness than ordinary tungsten and appreciable RT ductility in the recrystallized state. The other is an intergranular crack (IGC)-resistant austenitic stainless steel which was processed by the grain-boundary engineering (GBE). The experimental results are devoted to corrosion in a lead-bismuth eutectic, arrest of corrosion of weld-decay, radiation damage and creep rupture as well as new technique of GBE using a laser and annealing procedure. New technique seems to be applicable to large or complicated-shaped components. A series of the multi-scale models is built up from nuclear reaction between incident particles and medium nuclei to material property change due to radiation damage. Sample calculation is made on 3 mm-thick nickel bombarded by 3 GeV protons.

Kawai, Masayoshi; Kurishita, Hiroaki; Kokawa, Hiroyuki; Watanabe, Seiichi; Sakaguchi, Norihito; Kikuchi, Kenji; Saito, Shigeru; Yoshiie, Toshimasa; Iwase, Hiroshi; Ito, Takahiro; Hashimoto, Satoshi; Kaneko, Yoshihisa; Futakawa, Masatoshi; Ishino, Shiori; JSPS Grant Team

2012-12-01

92

Advances in large eddy simulation methodology for complex flows  

Microsoft Academic Search

A review is provided of the recent advances in the derivation of the constitutive equations for large eddy simulation, subgrid scale modeling, wall modeling and applications of LES to turbulent combustion. The majority of the paper focuses on a review of two numerical methods for LES in complex geometry: the immersed boundary method and an unstructured mesh scheme. The latter

Parviz Moin

2002-01-01

93

Advanced deformation process modeling  

SciTech Connect

Progress was made in achieving a comprehensive and coherent description of material behavior in deformation processing. The materials included were metals, alloys, intermetallic compounds, arbitrary lattice structure, and metal matrix composites. Aspects of behavior modeled included kinetics of flow and strain hardening, as well as recrystallization and the various anisotropies of strength and compliance. Highlights include a new prediction of the limiting strength of materials at high temperature, a new understanding of the generation of new grain boundaries during forming operations, and a quantitatively verified computer simulation of texture development and the resulting behavioral anisotropies.

Kocks, U.F.; Embury, J.D. [Los Alamos National Lab., NM (United States); Beaudoin, A.J. [Reynolds Metals (United States); Dawson, P.R. [Cornell Univ., Ithaca, NY (United States); MacEwen, S.R. [Alcan (Canada); Mecking, H.J. [Hamburg Technic (Germany)

1997-08-01

94

Advancing Climate and Carbon Simulation.  

National Technical Information Service (NTIS)

We use a recently developed integrated climate/carbon model to perform breakthrough studies of the climate. Two major studies are carried out--namely the effects of CO(sub 2)-fertilized vegetation on global climate and carbon dynamics, and the effect of c...

S. Thompson

2004-01-01

95

APAS: An Advanced Phased-Array Simulator  

Microsoft Academic Search

This article presents a description of the computer program APAS, a sophisticated phased-array simulator software package for the design and analysis of a wide variety of planar phased-array antennas. It offers accurate, high-speed computation of the far-field patterns of planar phased antennas, including advanced far-field analysis capabilities and comprehensive two-dimensional and three-dimensional visualization of the simulated results. The program was

Will P. M. N. Keizer

2010-01-01

96

Science based integrated approach to advanced nuclear fuel development - integrated multi-scale multi-physics hierarchical modeling and simulation framework Part III: cladding  

Microsoft Academic Search

Advancing the performance of Light Water Reactors, Advanced Nuclear Fuel Cycles, and Advanced Reactors, such as the Next Generation Nuclear Power Plants, requires enhancing our fundamental understanding of fuel and materials behavior under irradiation. The capability to accurately model the nuclear fuel systems to develop predictive tools is critical. Not only are fabrication and performance models needed to understand specific

Carlos N Tome; J A Caro; R A Lebensohn; Cetin Unal; A Arsenlis; J Marian; K Pasamehmetoglu

2010-01-01

97

Advanced ST Plasma Scenario Simulations for NSTX.  

National Technical Information Service (NTIS)

Integrated scenario simulations are done for NSTX that address four primary milestones for developing advanced ST configurations: high beta and high beta(subN) inductive discharges to study all aspects of ST physics in the high beta regime; non-inductivel...

C. E. Kessel E. J. Synakowski D. A. Gates R. W. Harvey S. M. Kaye

2004-01-01

98

Computational Models of Human Performance: Validation of Memory and Procedural Representation in Advanced Air/Ground Simulation  

NASA Technical Reports Server (NTRS)

The Man-Machine Interaction Design and Analysis System (MIDAS) under joint U.S. Army and NASA cooperative is intended to assist designers of complex human/automation systems in successfully incorporating human performance capabilities and limitations into decision and action support systems. MIDAS is a computational representation of multiple human operators, selected perceptual, cognitive, and physical functions of those operators, and the physical/functional representation of the equipment with which they operate. MIDAS has been used as an integrated predictive framework for the investigation of human/machine systems, particularly in situations with high demands on the operators. We have extended the human performance models to include representation of both human operators and intelligent aiding systems in flight management, and air traffic service. The focus of this development is to predict human performance in response to aiding system developed to identify aircraft conflict and to assist in the shared authority for resolution. The demands of this application requires representation of many intelligent agents sharing world-models, coordinating action/intention, and cooperative scheduling of goals and action in an somewhat unpredictable world of operations. In recent applications to airborne systems development, MIDAS has demonstrated an ability to predict flight crew decision-making and procedural behavior when interacting with automated flight management systems and Air Traffic Control. In this paper, we describe two enhancements to MIDAS. The first involves the addition of working memory in the form of an articulatory buffer for verbal communication protocols and a visuo-spatial buffer for communications via digital datalink. The second enhancement is a representation of multiple operators working as a team. This enhanced model was used to predict the performance of human flight crews and their level of compliance with commercial aviation communication procedures. We show how the data produced by MIDAS compares with flight crew performance data from full mission simulations. Finally, we discuss the use of these features to study communication issues connected with aircraft-based separation assurance.

Corker, Kevin M.; Labacqz, J. Victor (Technical Monitor)

1997-01-01

99

Advanced simulation of windmills in the electric power supply  

Microsoft Academic Search

An advanced model of a grid-connected windmill is set up where the windmill is a complex electro-mechanical system. The windmill model is implemented as a standardised component in the dynamic simulation tool, PSS\\/E, which makes it possible to investigate dynamic behaviour of grid-connected windmills as a part of realistic electrical grid models. This means an arbitrary number of wind farms

V. Akhmatov; H. Knudsen; A. H. Nielsen

2000-01-01

100

The Advanced Regional Prediction System (ARPS) – A multi-scale nonhydrostatic atmospheric simulation and prediction model. Part I: Model dynamics and verification  

Microsoft Academic Search

Summary  ?A completely new nonhydrostatic model system known as the Advanced Regional Prediction System (ARPS) has been developed in\\u000a recent years at the Center for Analysis and Prediction of Storms (CAPS) at the University of Oklahoma. The ARPS is designed\\u000a from the beginning to serve as an effective tool for basic and applied research and as a system suitable for explicit

M. Xue; K. K. Droegemeier; V. Wong

2000-01-01

101

Advances in the Modelling of Motorcycle Dynamics  

Microsoft Academic Search

Starting from an existing advanced motorcycle dynamics model, which allows simulation of reasonably general motions and stability, modal and response computations for small perturbations from any trim condition, improvements are described. These concern (a) tyre\\/road contact geometry, (b) tyre shear force and moment descriptions, as functions of load, slip and camber, (c) tyre relaxation properties, (d) a new analytic treatment

R. S. Sharp; S. Evangelou; D. J. N. Limebeer

2004-01-01

102

Sizing the Motion Base of the National Advanced Driving Simulator.  

National Technical Information Service (NTIS)

The National Advanced Driving Simulator (NADS) will move the simulator's cab so that realistic motion cues are provided to the simulator's driver. It is necessary to determine the motion base capabilities that the NADS will need to simulate different seve...

W. R. Garrott

1993-01-01

103

Center for Simulation of Advanced Rockets (CSAR): Gallery of Images from Advanced Rockets Simulations  

DOE Data Explorer

The Center for Simulation of Advanced Rockets (CSAR) is one of five university-based Centers of Excellence founded in 1997 and funded by the U.S. Department of Energy's Advanced Simulation and Computing program, whose objective is to enable accurate prediction of the performance, reliability, and safety of complex physical systems through computational simulation. CSAR's mission is to achieve this goal in the specific context of solid propellant rockets, which are of vital importance to the space launch industry. A particular focus for CSAR is on the reusable solid rocket motor (RSRM) that powers the U.S. Space Shuttle.

104

Modeling and Simulation of Mold Filling with LIMS.  

National Technical Information Service (NTIS)

Outline of presentation: What is the Computer Simulation (Modeling). Why do we need simulation. Computer modeling-Basics: experimental characterization; process modeling, analytic and numeric; Computer modeling-Advanced: control and sensing; optimization;...

P. Simacek

2003-01-01

105

Advanced manufacturing of large-scale composite structures: process modeling, manufacturing simulations and massively parallel computing platforms  

Microsoft Academic Search

Newly emerging composite manufacturing processes, where there exist only limited industrial experience, demonstrate a definite need for process simulations to reduce the time and cost associated with the product and process developments. The physical and geometric complexity of the net-shape composite structural parts produced by resin transfer molding (RTM) lead to larger computational problem sizes and computational complexity demanding more

R. V. Mohan; K. K. Tamma; D. R. Shires; A. Mark

1998-01-01

106

Chemical Kinetic Modeling of Advanced Transportation Fuels  

SciTech Connect

Development of detailed chemical kinetic models for advanced petroleum-based and nonpetroleum based fuels is a difficult challenge because of the hundreds to thousands of different components in these fuels and because some of these fuels contain components that have not been considered in the past. It is important to develop detailed chemical kinetic models for these fuels since the models can be put into engine simulation codes used for optimizing engine design for maximum efficiency and minimal pollutant emissions. For example, these chemistry-enabled engine codes can be used to optimize combustion chamber shape and fuel injection timing. They also allow insight into how the composition of advanced petroleum-based and non-petroleum based fuels affect engine performance characteristics. Additionally, chemical kinetic models can be used separately to interpret important in-cylinder experimental data and gain insight into advanced engine combustion processes such as HCCI and lean burn engines. The objectives are: (1) Develop detailed chemical kinetic reaction models for components of advanced petroleum-based and non-petroleum based fuels. These fuels models include components from vegetable-oil-derived biodiesel, oil-sand derived fuel, alcohol fuels and other advanced bio-based and alternative fuels. (2) Develop detailed chemical kinetic reaction models for mixtures of non-petroleum and petroleum-based components to represent real fuels and lead to efficient reduced combustion models needed for engine modeling codes. (3) Characterize the role of fuel composition on efficiency and pollutant emissions from practical automotive engines.

PItz, W J; Westbrook, C K; Herbinet, O

2009-01-20

107

Advanced Techniques for Reservoir Simulation and Modeling of Nonconventional Wells. Final Report, September 1, 1999-August 31, 2004.  

National Technical Information Service (NTIS)

Research results for a five year project on the development of improved modeling techniques for nonconventional (e.g., horizontal, deviated, multilateral or smart) wells are presented. The overall program entails the development of enhanced well modeling ...

K. Aziz L. J. Durlofsky

1999-01-01

108

Experimental advanced superconducting tokamak ohmic discharge simulation by the tokamak simulation code  

NASA Astrophysics Data System (ADS)

The tokamak simulation code (TSC) has been used to model several ohmic discharges in the experimental advanced superconducting tokamak (EAST) experiments. Good agreement between the simulation and experiment has been obtained in the plasma current and shape evolution, as well as electron temperature, surface voltage and volt-second consumption. With the verified TSC transport models, an ohmic discharge has been predicted. The poloidal field current trajectories, plasma current and shape evolution follow the designed traces in the experiment.

Guo, Yong; Xiao, Bingjia; Wu, Bin; Liu, Chengyue

2012-08-01

109

Hybrid and electric advanced vehicle systems (heavy) simulation  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

110

Nuclear Energy Advanced Modeling and Simulation (NEAMS) waste Integrated Performance and Safety Codes (IPSC) : gap analysis for high fidelity and performance assessment code development.  

SciTech Connect

This report describes a gap analysis performed in the process of developing the Waste Integrated Performance and Safety Codes (IPSC) in support of the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign. The goal of the Waste IPSC is to develop an integrated suite of computational modeling and simulation capabilities to quantitatively assess the long-term performance of waste forms in the engineered and geologic environments of a radioactive waste storage or disposal system. The Waste IPSC will provide this simulation capability (1) for a range of disposal concepts, waste form types, engineered repository designs, and geologic settings, (2) for a range of time scales and distances, (3) with appropriate consideration of the inherent uncertainties, and (4) in accordance with rigorous verification, validation, and software quality requirements. The gap analyses documented in this report were are performed during an initial gap analysis to identify candidate codes and tools to support the development and integration of the Waste IPSC, and during follow-on activities that delved into more detailed assessments of the various codes that were acquired, studied, and tested. The current Waste IPSC strategy is to acquire and integrate the necessary Waste IPSC capabilities wherever feasible, and develop only those capabilities that cannot be acquired or suitably integrated, verified, or validated. The gap analysis indicates that significant capabilities may already exist in the existing THC codes although there is no single code able to fully account for all physical and chemical processes involved in a waste disposal system. Large gaps exist in modeling chemical processes and their couplings with other processes. The coupling of chemical processes with flow transport and mechanical deformation remains challenging. The data for extreme environments (e.g., for elevated temperature and high ionic strength media) that are needed for repository modeling are severely lacking. In addition, most of existing reactive transport codes were developed for non-radioactive contaminants, and they need to be adapted to account for radionuclide decay and in-growth. The accessibility to the source codes is generally limited. Because the problems of interest for the Waste IPSC are likely to result in relatively large computational models, a compact memory-usage footprint and a fast/robust solution procedure will be needed. A robust massively parallel processing (MPP) capability will also be required to provide reasonable turnaround times on the analyses that will be performed with the code. A performance assessment (PA) calculation for a waste disposal system generally requires a large number (hundreds to thousands) of model simulations to quantify the effect of model parameter uncertainties on the predicted repository performance. A set of codes for a PA calculation must be sufficiently robust and fast in terms of code execution. A PA system as a whole must be able to provide multiple alternative models for a specific set of physical/chemical processes, so that the users can choose various levels of modeling complexity based on their modeling needs. This requires PA codes, preferably, to be highly modularized. Most of the existing codes have difficulties meeting these requirements. Based on the gap analysis results, we have made the following recommendations for the code selection and code development for the NEAMS waste IPSC: (1) build fully coupled high-fidelity THCMBR codes using the existing SIERRA codes (e.g., ARIA and ADAGIO) and platform, (2) use DAKOTA to build an enhanced performance assessment system (EPAS), and build a modular code architecture and key code modules for performance assessments. The key chemical calculation modules will be built by expanding the existing CANTERA capabilities as well as by extracting useful components from other existing codes.

Lee, Joon H.; Siegel, Malcolm Dean; Arguello, Jose Guadalupe, Jr.; Webb, Stephen Walter; Dewers, Thomas A.; Mariner, Paul E.; Edwards, Harold Carter; Fuller, Timothy J.; Freeze, Geoffrey A.; Jove-Colon, Carlos F.; Wang, Yifeng

2011-03-01

111

A hybrid-Vlasov model based on the current advance method for the simulation of collisionless magnetized plasma  

SciTech Connect

We present a numerical scheme for the integration of the Vlasov-Maxwell system of equations for a non-relativistic plasma, in the hybrid approximation, where the Vlasov equation is solved for the ion distribution function and the electrons are treated as a fluid. In the Ohm equation for the electric field, effects of electron inertia have been retained, in order to include the small scale dynamics up to characteristic lengths of the order of the electron skin depth. The low frequency approximation is used by neglecting the time derivative of the electric field, i.e. the displacement current in the Ampere equation. The numerical algorithm consists in coupling the splitting method proposed by Cheng and Knorr in 1976 [C.Z. Cheng, G. Knorr, J. Comput. Phys. 22 (1976) 330-351.] and the current advance method (CAM) introduced by Matthews in 1994 [A.P. Matthews, J. Comput. Phys. 112 (1994) 102-116.] In its present version, the code solves the Vlasov-Maxwell equations in a five-dimensional phase space (2-D in the physical space and 3-D in the velocity space) and it is implemented in a parallel version to exploit the computational power of the modern massively parallel supercomputers. The structure of the algorithm and the coupling between the splitting method and the CAM method (extended to the hybrid case) is discussed in detail. Furthermore, in order to test the hybrid-Vlasov code, the numerical results on propagation and damping of linear ion-acoustic modes and time evolution of linear elliptically polarized Alfven waves (including the so-called whistler regime) are compared to the analytical solutions. Finally, the numerical results of the hybrid-Vlasov code on the parametric instability of Alfven waves are compared with those obtained using a two-fluid approach.

Valentini, F. [Dipartimento di Fisica and CNISM, Universita degli Studi della Calabria, Ponte P. Bucci, Cubo 31C, 87036 Arcavacata di Rende (Serbia and Montenegro) (Italy)]. E-mail: valentin@fis.unical.it; Travnicek, P. [Institute of Atmospheric Physics, AS CR, Prague (Czech Republic); Califano, F. [Dipartimento di Fisica and CNISM, Universita di Pisa, Pisa (Italy); Hellinger, P. [Institute of Atmospheric Physics, AS CR, Prague (Czech Republic); Mangeney, A. [LESIA - Observatoire de Paris, Section de Meudon 5, place Jules Janssen, 92195 Meudon Cedex (France)

2007-07-01

112

The Impact of the Assimilation of Hyperspectral Infrared Retrieved Profiles on Advanced Weather and Research Model Simulations of a Non-Convective Wind Event  

NASA Technical Reports Server (NTRS)

Non-convective wind events commonly occur with passing extratropical cyclones and have significant societal and economic impacts. Since non-convective winds often occur in the absence of specific phenomena such as a thunderstorm, tornado, or hurricane, the public are less likely to heed high wind warnings and continue daily activities. Thus non-convective wind events result in as many fatalities as straight line thunderstorm winds. One physical explanation for non-convective winds includes tropopause folds. Improved model representation of stratospheric air and associated non-convective wind events could improve non-convective wind forecasts and associated warnings. In recent years, satellite data assimilation has improved skill in forecasting extratropical cyclones; however errors still remain in forecasting the position and strength of extratropical cyclones as well as the tropopause folding process. The goal of this study is to determine the impact of assimilating satellite temperature and moisture retrieved profiles from hyperspectral infrared (IR) sounders (i.e. Atmospheric Infrared Sounder (AIRS), Cross-track Infrared and Microwave Sounding Suite (CrIMSS), and Infrared Atmospheric Sounding Interferometer (IASI)) on the model representation of the tropopause fold and an associated high wind event that impacted the Northeast United States on 09 February 2013. Model simulations using the Advanced Research Weather Research and Forecasting Model (ARW) were conducted on a 12-km grid with cycled data assimilation mimicking the operational North American Model (NAM). The results from the satellite assimilation run are compared to a control experiment (without hyperspectral IR retrievals), Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis, and Rapid Refresh analyses.

Berndt, Emily; Zavodsky, Bradley; Jedlovec, Gary; Elmer, Nicholas

2013-01-01

113

Impact of the Assimilation of Hyperspectral Infrared Retrieved Profiles on Advanced Weather and Research Model Simulations of a Non-Convective Wind Event  

NASA Technical Reports Server (NTRS)

Non-convective wind events commonly occur with passing extratropical cyclones and have significant societal and economic impacts. Since non-convective winds often occur in the absence of specific phenomena such as a thunderstorm, tornado, or hurricane, the public are less likely to heed high wind warnings and continue daily activities. Thus non-convective wind events result in as many fatalities as straight line thunderstorm winds. One physical explanation for non-convective winds includes tropopause folds. Improved model representation of stratospheric air and associated non-convective wind events could improve non-convective wind forecasts and associated warnings. In recent years, satellite data assimilation has improved skill in forecasting extratropical cyclones; however errors still remain in forecasting the position and strength of extratropical cyclones as well as the tropopause folding process. The goal of this study is to determine the impact of assimilating satellite temperature and moisture retrieved profiles from hyperspectral infrared (IR) sounders (i.e. Atmospheric Infrared Sounder (AIRS), Cross-track Infrared and Microwave Sounding Suite (CrIMSS), and Infrared Atmospheric Sounding Interferometer (IASI)) on the model representation of the tropopause fold and an associated high wind event that impacted the Northeast United States on 09 February 2013. Model simulations using the Advanced Research Weather Research and Forecasting Model (ARW) were conducted on a 12-km grid with cycled data assimilation mimicking the operational North American Model (NAM). The results from the satellite assimilation run are compared to a control experiment (without hyperspectral IR retrievals), Modern Era-Retrospective Analysis for Research and Applications (MERRA) reanalysis, and Rapid Refresh analyses.

Berndt, E. B.; Zavodsky, B. T.; Jedlovec, G. J.

2014-01-01

114

Impact of the Assimilation of Hyperspectral Infrared Profiles on Advanced Weather and Research Model Simulations of a Non-Convective Wind Event  

NASA Technical Reports Server (NTRS)

Non-convective wind events commonly occur with passing extratropical cyclones and have significant societal and economic impacts. Since non-convective winds often occur in the absence of specific phenomena such as a thunderstorm, tornado, or hurricane, the public are less likely to heed high wind warnings and continue daily activities. Thus non-convective wind events result in as many fatalities as straight line thunderstorm winds. One physical explanation for non-convective winds includes tropopause folds. Improved model representation of stratospheric air and associated non-convective wind events could improve non-convective wind forecasts and associated warnings. In recent years, satellite data assimilation has improved skill in forecasting extratropical cyclones; however errors still remain in forecasting the position and strength of extratropical cyclones as well as the tropopause folding process. The goal of this study is to determine the impact of assimilating satellite temperature and moisture retrieved profiles from hyperspectral infrared (IR) sounders (i.e. Atmospheric Infrared Sounder (AIRS), Cross-track Infrared and Microwave Sounding Suite (CrIMSS), and Infrared Atmospheric Sounding Interferometer (IASI)) on the model representation of the tropopause fold and an associated high wind event that impacted the Northeast United States on 09 February 2013. Model simulations using the Advanced Research Weather Research and Forecasting Model (ARW) were conducted on a 12-km grid with cycled data assimilation mimicking the operational North American Model (NAM). The results from the satellite assimilation run are compared to a control experiment (without hyperspectral IR retrievals), North American Regional Reanalysis (NARR) reanalysis, and Rapid Refresh analyses.

Berndt, Emily B.; Zavodsky, Bradley T; Jedlovec, Gary J.; Elmer, Nicholas J.

2013-01-01

115

Guide to Computer Simulations of Three Adaptive Instructional Models for the Advanced Instructional System Phases II and III.  

National Technical Information Service (NTIS)

The report concludes Phases 2 and 3 of Air Force research on the application of adaptive instructional models (AIM) to individualized technical training. Phase 1 research concluded with a recommendation to employ five state-of-the-art AIMs: (1) Drill and ...

D. N. Hansen H. D. Kribs R. Tennyson S. Taylor T. James

1973-01-01

116

Nuclear Energy Advanced Modeling and Simulation Waste Integrated Performance and Safety Codes (NEAMS Waste IPSC) verification and validation plan. version 1.  

SciTech Connect

The objective of the U.S. Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation Waste Integrated Performance and Safety Codes (NEAMS Waste IPSC) is to provide an integrated suite of computational modeling and simulation (M&S) capabilities to quantitatively assess the long-term performance of waste forms in the engineered and geologic environments of a radioactive-waste storage facility or disposal repository. To meet this objective, NEAMS Waste IPSC M&S capabilities will be applied to challenging spatial domains, temporal domains, multiphysics couplings, and multiscale couplings. A strategic verification and validation (V&V) goal is to establish evidence-based metrics for the level of confidence in M&S codes and capabilities. Because it is economically impractical to apply the maximum V&V rigor to each and every M&S capability, M&S capabilities will be ranked for their impact on the performance assessments of various components of the repository systems. Those M&S capabilities with greater impact will require a greater level of confidence and a correspondingly greater investment in V&V. This report includes five major components: (1) a background summary of the NEAMS Waste IPSC to emphasize M&S challenges; (2) the conceptual foundation for verification, validation, and confidence assessment of NEAMS Waste IPSC M&S capabilities; (3) specifications for the planned verification, validation, and confidence-assessment practices; (4) specifications for the planned evidence information management system; and (5) a path forward for the incremental implementation of this V&V plan.

Bartlett, Roscoe Ainsworth; Arguello, Jose Guadalupe, Jr.; Urbina, Angel; Bouchard, Julie F.; Edwards, Harold Carter; Freeze, Geoffrey A.; Knupp, Patrick Michael; Wang, Yifeng; Schultz, Peter Andrew; Howard, Robert (Oak Ridge National Laboratory, Oak Ridge, TN); McCornack, Marjorie Turner

2011-01-01

117

Advanced Chemistry Basins Model  

SciTech Connect

The objective of this project is to: (1) Develop a database of additional and better maturity indicators for paleo-heat flow calibration; (2) Develop maturation models capable of predicting the chemical composition of hydrocarbons produced by a specific kerogen as a function of maturity, heating rate, etc.; assemble a compositional kinetic database of representative kerogens; (3) Develop a 4 phase equation of state-flash model that can define the physical properties (viscosity, density, etc.) of the products of kerogen maturation, and phase transitions that occur along secondary migration pathways; (4) Build a conventional basin model and incorporate new maturity indicators and data bases in a user-friendly way; (5) Develop an algorithm which combines the volume change and viscosities of the compositional maturation model to predict the chemistry of the hydrocarbons that will be expelled from the kerogen to the secondary migration pathways; (6) Develop an algorithm that predicts the flow of hydrocarbons along secondary migration pathways, accounts for mixing of miscible hydrocarbon components along the pathway, and calculates the phase fractionation that will occur as the hydrocarbons move upward down the geothermal and fluid pressure gradients in the basin; and (7) Integrate the above components into a functional model implemented on a PC or low cost workstation.

Blanco, Mario; Cathles, Lawrence; Manhardt, Paul; Meulbroek, Peter; Tang, Yongchun

2003-02-13

118

Aviation Safety Simulation Model  

NASA Technical Reports Server (NTRS)

The Aviation Safety Simulation Model is a software tool that enables users to configure a terrain, a flight path, and an aircraft and simulate the aircraft's flight along the path. The simulation monitors the aircraft's proximity to terrain obstructions, and reports when the aircraft violates accepted minimum distances from an obstruction. This model design facilitates future enhancements to address other flight safety issues, particularly air and runway traffic scenarios. This report shows the user how to build a simulation scenario and run it. It also explains the model's output.

Houser, Scott; Yackovetsky, Robert (Technical Monitor)

2001-01-01

119

Interactive visualization to advance earthquake simulation  

USGS Publications Warehouse

The geological sciences are challenged to manage and interpret increasing volumes of data as observations and simulations increase in size and complexity. For example, simulations of earthquake-related processes typically generate complex, time-varying data sets in two or more dimensions. To facilitate interpretation and analysis of these data sets, evaluate the underlying models, and to drive future calculations, we have developed methods of interactive visualization with a special focus on using immersive virtual reality (VR) environments to interact with models of Earth's surface and interior. Virtual mapping tools allow virtual "field studies" in inaccessible regions. Interactive tools allow us to manipulate shapes in order to construct models of geological features for geodynamic models, while feature extraction tools support quantitative measurement of structures that emerge from numerical simulation or field observations, thereby enabling us to improve our interpretation of the dynamical processes that drive earthquakes. VR has traditionally been used primarily as a presentation tool, albeit with active navigation through data. Reaping the full intellectual benefits of immersive VR as a tool for scientific analysis requires building on the method's strengths, that is, using both 3D perception and interaction with observed or simulated data. This approach also takes advantage of the specialized skills of geological scientists who are trained to interpret, the often limited, geological and geophysical data available from field observations. ?? Birkhaueser 2008.

Kellogg, L. H.; Bawden, G. W.; Bernardin, T.; Billen, M.; Cowgill, E.; Hamann, B.; Jadamec, M.; Kreylos, O.; Staadt, O.; Sumner, D.

2008-01-01

120

Interactive Visualization to Advance Earthquake Simulation  

NASA Astrophysics Data System (ADS)

The geological sciences are challenged to manage and interpret increasing volumes of data as observations and simulations increase in size and complexity. For example, simulations of earthquake-related processes typically generate complex, time-varying data sets in two or more dimensions. To facilitate interpretation and analysis of these data sets, evaluate the underlying models, and to drive future calculations, we have developed methods of interactive visualization with a special focus on using immersive virtual reality (VR) environments to interact with models of Earth’s surface and interior. Virtual mapping tools allow virtual “field studies” in inaccessible regions. Interactive tools allow us to manipulate shapes in order to construct models of geological features for geodynamic models, while feature extraction tools support quantitative measurement of structures that emerge from numerical simulation or field observations, thereby enabling us to improve our interpretation of the dynamical processes that drive earthquakes. VR has traditionally been used primarily as a presentation tool, albeit with active navigation through data. Reaping the full intellectual benefits of immersive VR as a tool for scientific analysis requires building on the method’s strengths, that is, using both 3D perception and interaction with observed or simulated data. This approach also takes advantage of the specialized skills of geological scientists who are trained to interpret, the often limited, geological and geophysical data available from field observations.

Kellogg, Louise H.; Bawden, Gerald W.; Bernardin, Tony; Billen, Magali; Cowgill, Eric; Hamann, Bernd; Jadamec, Margarete; Kreylos, Oliver; Staadt, Oliver; Sumner, Dawn

2008-04-01

121

Modeling and simulation  

SciTech Connect

This book presents the papers given at a conference on computerized simulation. Topics considered at the conference included expert systems, modeling in electric power systems, power systems operating strategies, energy analysis, a linear programming approach to optimum load shedding in transmission systems, econometrics, simulation in natural gas engineering, solar energy studies, artificial intelligence, vision systems, hydrology, multiprocessors, and flow models.

Hanham, R.; Vogt, W.G.; Mickle, M.H.

1986-01-01

122

Modelling and simulation in reactive polymer processing  

Microsoft Academic Search

Modelling and simulation in reactive polymer processing have been active research areas for the past decades in academic institutions as well as within the industry. Both areas have played a key role in advancing and optimizing reactive polymer processing operations. The objective of this paper is to review the two major classifications of models used to simulate polymer processes: physics

José M Castro; Mauricio Cabrera Ríos; Clark A Mount-Campbell

2004-01-01

123

Advances in Simulation of Wave Interaction with Extended MHD Phenomena  

SciTech Connect

The Integrated Plasma Simulator (IPS) provides a framework within which some of the most advanced, massively-parallel fusion modeling codes can be interoperated to provide a detailed picture of the multi-physics processes involved in fusion experiments. The presentation will cover four topics: 1) recent improvements to the IPS, 2) application of the IPS for very high resolution simulations of ITER scenarios, 3) studies of resistive and ideal MHD stability in tokamk discharges using IPS facilities, and 4) the application of RF power in the electron cyclotron range of frequencies to control slowly growing MHD modes in tokamaks and initial evaluations of optimized location for RF power deposition.

Batchelor, Donald B [ORNL; Abla, Gheni [ORNL; D'Azevedo, Ed F [ORNL; Bateman, Glenn [Lehigh University, Bethlehem, PA; Bernholdt, David E [ORNL; Berry, Lee A [ORNL; Bonoli, P. [Massachusetts Institute of Technology (MIT); Bramley, R [Indiana University; Breslau, Joshua [ORNL; Chance, M. [Princeton Plasma Physics Laboratory (PPPL); Chen, J. [Princeton Plasma Physics Laboratory (PPPL); Choi, M. [General Atomics; Elwasif, Wael R [ORNL; Foley, S. [Indiana University; Fu, GuoYong [Princeton Plasma Physics Laboratory (PPPL); Harvey, R. W. [CompX, Del Mar, CA; Jaeger, Erwin Frederick [ORNL; Jardin, S. C. [Princeton Plasma Physics Laboratory (PPPL); Jenkins, T [University of Wisconsin; Keyes, David E [Columbia University; Klasky, Scott A [ORNL; Kruger, Scott [Tech-X Corporation; Ku, Long-Poe [Princeton Plasma Physics Laboratory (PPPL); Lynch, Vickie E [ORNL; McCune, Douglas [Princeton Plasma Physics Laboratory (PPPL); Ramos, J. [Massachusetts Institute of Technology (MIT); Schissel, D. [General Atomics; Schnack, [University of Wisconsin; Wright, J. [Massachusetts Institute of Technology (MIT)

2009-01-01

124

Advances in Simulation of Wave Interactions with Extended MHD Phenomena  

SciTech Connect

The Integrated Plasma Simulator (IPS) provides a framework within which some of the most advanced, massively-parallel fusion modeling codes can be interoperated to provide a detailed picture of the multi-physics processes involved in fusion experiments. The presentation will cover four topics: (1) recent improvements to the IPS, (2) application of the IPS for very high resolution simulations of ITER scenarios, (3) studies of resistive and ideal MHD stability in tokamak discharges using IPS facilities, and (4) the application of RF power in the electron cyclotron range of frequencies to control slowly growing MHD modes in tokamaks and initial evaluations of optimized location for RF power deposition.

Batchelor, Donald B [ORNL] [ORNL; D'Azevedo, Eduardo [ORNL] [ORNL; Bateman, Glenn [ORNL] [ORNL; Bernholdt, David E [ORNL] [ORNL; Bonoli, P. [Massachusetts Institute of Technology (MIT)] [Massachusetts Institute of Technology (MIT); Bramley, Randall B [ORNL] [ORNL; Breslau, Joshua [ORNL] [ORNL; Elwasif, Wael R [ORNL] [ORNL; Foley, S. [Indiana University] [Indiana University; Jaeger, Erwin Frederick [ORNL] [ORNL; Jardin, S. C. [Princeton Plasma Physics Laboratory (PPPL)] [Princeton Plasma Physics Laboratory (PPPL); Klasky, Scott A [ORNL] [ORNL; Kruger, Scott E [ORNL] [ORNL; Ku, Long-Poe [ORNL] [ORNL; McCune, Douglas [Princeton Plasma Physics Laboratory (PPPL)] [Princeton Plasma Physics Laboratory (PPPL); Ramos, J. [Massachusetts Institute of Technology (MIT)] [Massachusetts Institute of Technology (MIT); Schissel, David P [ORNL] [ORNL; Schnack, Dalton D [ORNL] [ORNL

2009-01-01

125

Simulating advanced life support systems to test integrated control approaches  

NASA Astrophysics Data System (ADS)

Simulations allow for testing of life support control approaches before hardware is designed and built. Simulations also allow for the safe exploration of alternative control strategies during life support operation. As such, they are an important component of any life support research program and testbed. This paper describes a specific advanced life support simulation being created at NASA Johnson Space Center. It is a discrete-event simulation that is dynamic and stochastic. It simulates all major components of an advanced life support system, including crew (with variable ages, weights and genders), biomass production (with scalable plantings of ten different crops), water recovery, air revitalization, food processing, solid waste recycling and energy production. Each component is modeled as a producer of certain resources and a consumer of certain resources. The control system must monitor (via sensors) and control (via actuators) the flow of resources throughout the system to provide life support functionality. The simulation is written in an object-oriented paradigm that makes it portable, extensible and reconfigurable.

Kortenkamp, D.; Bell, S.

126

Recent advances in superconducting-mixer simulations  

NASA Astrophysics Data System (ADS)

Over the last few years, considerable progress have been made in the development of techniques for fabricating high-quality superconducting circuits, and this success, together with major advances in the theoretical understanding of quantum detection and mixing at millimeter and submillimeter wavelengths, has made the development of CAD techniques for superconducting nonlinear circuits an important new enterprise. For example, arrays of quasioptical mixers are now being manufactured, where the antennas, matching networks, filters and superconducting tunnel junctions are all fabricated by depositing niobium and a variety of oxides on a single quartz substrate. There are no adjustable tuning elements on these integrated circuits, and therefore, one must be able to predict their electrical behavior precisely. This requirement, together with a general interest in the generic behavior of devices such as direct detectors and harmonic mixers, has lead us to develop a range of CAD tools for simulating the large-signal, small-signal, and noise behavior of superconducting tunnel junction circuits.

Withington, S.; Kennedy, P. R.

127

Recent advances in superconducting-mixer simulations  

NASA Technical Reports Server (NTRS)

Over the last few years, considerable progress have been made in the development of techniques for fabricating high-quality superconducting circuits, and this success, together with major advances in the theoretical understanding of quantum detection and mixing at millimeter and submillimeter wavelengths, has made the development of CAD techniques for superconducting nonlinear circuits an important new enterprise. For example, arrays of quasioptical mixers are now being manufactured, where the antennas, matching networks, filters and superconducting tunnel junctions are all fabricated by depositing niobium and a variety of oxides on a single quartz substrate. There are no adjustable tuning elements on these integrated circuits, and therefore, one must be able to predict their electrical behavior precisely. This requirement, together with a general interest in the generic behavior of devices such as direct detectors and harmonic mixers, has lead us to develop a range of CAD tools for simulating the large-signal, small-signal, and noise behavior of superconducting tunnel junction circuits.

Withington, S.; Kennedy, P. R.

1992-01-01

128

Accuracy of 3D optical lithography simulation for advanced reticles  

NASA Astrophysics Data System (ADS)

Optical lithography over the next few product generations will demand the use of various types of advanced reticles (OPC, attenuated phase shift, alternating phase shift, etc.). Planing for these generations relies ever more heavily on simulation to make intelligent choices among the options in exposure wavelength, numerical aperture, reticle type and design, etc. Simulation of resist exposures of 2-dimensional reticle patterns becomes increasingly important, since some 2- D reticle patterns (and resulting 3-D resist patterns) are crucial to the device structure and at the same time the most sensitive to resolution limitations. Simulation of arbitrary 2-D mask structures is also a much more difficult task than for 1-D reticle patterns, requiring not only more computing power but more complex algorithms. These structures pose a severe challenge to the calibration of a simulation tool: however, this is also an opportunity to make a simulation program more useful by demonstrating more predictive power. We present experimental data and simulations illustrating progress towards calibration accuracy on some key 3-D resist patterns for a 0.25 micrometer lithography process. Careful calibration of the model provides for accurate simulation under a wide variety of conditions, thus allowing the use of simulation for critical feature mask design.

Hollman, Richard F.; Mack, Chris A.

1997-02-01

129

ADVANCED MIXING MODELS  

SciTech Connect

The process of recovering and processing High Level Waste (HLW) the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank with one to four mixers (pumps) located within the tank. The typical criteria to establish a mixed condition in a tank are based on the number of pumps in operation and the time duration of operation. To ensure that a mixed condition is achieved, operating times are typically set conservatively long. This approach results in high operational costs because of the long mixing times and high maintenance and repair costs for the same reason. A significant reduction in both of these costs might be realized by reducing the required mixing time based on calculating a reliable indicator of mixing with a suitably validated computer code. The focus of the present work is to establish mixing criteria applicable to miscible fluids, with an ultimate goal of addressing waste processing in HLW tanks at SRS and quantifying the mixing time required to suspend sludge particles with the submersible jet pump. A single-phase computational fluid dynamics (CFD) approach was taken for the analysis of jet flow patterns with an emphasis on the velocity decay and the turbulent flow evolution for the farfield region from the pump. Literature results for a turbulent jet flow are reviewed, since the decay of the axial jet velocity and the evolution of the jet flow patterns are important phenomena affecting sludge suspension and mixing operations. The work described in this report suggests a basis for further development of the theory leading to the identified mixing indicators, with benchmark analyses demonstrating their consistency with widely accepted correlations. Although the indicators are somewhat generic in nature, they are applied to Savannah River Site (SRS) waste tanks to provide a better, physically based estimate of the required mixing time. Waste storage tanks at SRS contain settled sludge which varies in height from zero to 10 ft. The sludge has been characterized and modeled as micron-sized solids, typically 1 to 5 microns, at weight fractions as high as 20 to 30 wt%, specific gravities to 1.4, and viscosities up to 64 cp during motion. The sludge is suspended and mixed through the use of submersible slurry jet pumps. To suspend settled sludge, water is added to the tank as a slurry medium and stirred with the jet pump. Although there is considerable technical literature on mixing and solid suspension in agitated tanks, very little literature has been published on jet mixing in a large-scale tank. One of the main objectives in the waste processing is to provide feed of a uniform slurry composition at a certain weight percentage (e.g. typically {approx}13 wt% at SRS) over an extended period of time. In preparation of the sludge for slurrying, several important questions have been raised with regard to sludge suspension and mixing of the solid suspension in the bulk of the tank: (1) How much time is required to prepare a slurry with a uniform solid composition? (2) How long will it take to suspend and mix the sludge for uniform composition in any particular waste tank? (3) What are good mixing indicators to answer the questions concerning sludge mixing stated above in a general fashion applicable to any waste tank/slurry pump geometry and fluid/sludge combination?

Lee, S.; Dimenna, R.; Tamburello, D.

2011-02-14

130

ADVANCED MIXING MODELS  

SciTech Connect

The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank with one to four dual-nozzle jet mixers located within the tank. The typical criteria to establish a mixed condition in a tank are based on the number of pumps in operation and the time duration of operation. To ensure that a mixed condition is achieved, operating times are set conservatively long. This approach results in high operational costs because of the long mixing times and high maintenance and repair costs for the same reason. A significant reduction in both of these costs might be realized by reducing the required mixing time based on calculating a reliable indicator of mixing with a suitably validated computer code. The work described in this report establishes the basis for further development of the theory leading to the identified mixing indicators, the benchmark analyses demonstrating their consistency with widely accepted correlations, and the application of those indicators to SRS waste tanks to provide a better, physically based estimate of the required mixing time. Waste storage tanks at SRS contain settled sludge which varies in height from zero to 10 ft. The sludge has been characterized and modeled as micron-sized solids, typically 1 to 5 microns, at weight fractions as high as 20 to 30 wt%, specific gravities to 1.4, and viscosities up to 64 cp during motion. The sludge is suspended and mixed through the use of submersible slurry jet pumps. To suspend settled sludge, water is added to the tank as a slurry medium and stirred with the jet pump. Although there is considerable technical literature on mixing and solid suspension in agitated tanks, very little literature has been published on jet mixing in a large-scale tank. If shorter mixing times can be shown to support Defense Waste Processing Facility (DWPF) or other feed requirements, longer pump lifetimes can be achieved with associated operational cost and schedule savings. The focus of the present work is to establish mixing criteria associated with the waste processing at SRS and to quantify the mixing time required to suspend sludge particles with the submersible jet pump. Literature results for a turbulent jet flow are reviewed briefly, since the decay of the axial jet velocity and the evolution of the jet flow patterns are important phenomena affecting sludge suspension and mixing operations. One of the main objectives in the waste processing is to provide the DWPF a uniform slurry composition at a certain weight percentage (typically {approx}13 wt%) over an extended period of time. In preparation of the sludge for slurrying to DWPF, several important questions have been raised with regard to sludge suspension and mixing of the solid suspension in the bulk of the tank: (1) How much time is required to prepare a slurry with a uniform solid composition for DWPF? (2) How long will it take to suspend and mix the sludge for uniform composition in any particular waste tank? (3) What are good mixing indicators to answer the questions concerning sludge mixing stated above in a general fashion applicable to any waste tank/slurry pump geometry and fluid/sludge combination? Grenville and Tilton (1996) investigated the mixing process by giving a pulse of tracer (electrolyte) through the submersible jet nozzle and by monitoring the conductivity at three locations within the cylindrical tank. They proposed that the mixing process was controlled by the turbulent kinetic energy dissipation rate in the region far away from the jet entrance. They took the energy dissipation rates in the regions remote from the nozzle to be proportional to jet velocity and jet diameter at that location. The reduction in the jet velocity was taken to be proportional to the nozzle velocity and distance from the nozzle. Based on their analysis, a correlation was proposed. The proposed correlation was shown to be valid over a wide range of Reynolds numbers (50,000 to 300,000) with a relative standard deviation of {+-} 11.83%. An improved correlat

Lee, S; Richard Dimenna, R; David Tamburello, D

2008-11-13

131

Wilderness Area Simulation Model.  

National Technical Information Service (NTIS)

The computer program for a simulation model for travel and encounters in wilderness areas is available to managers for testing alternative wilderness management strategies. Detailed technical information can be obtained from the U.S. Forest Service, Compu...

N. A. Heck D. B. Webster

1973-01-01

132

Mrbc Simulation Model.  

National Technical Information Service (NTIS)

A simulation was developed as a technique for analyzing and testing possible solutions for a centralized inventory control system for blood banking in the Chicago area. The model provides methods for studying the effects of different inventory techniques ...

T. R. Jobe

1969-01-01

133

Interoperable Technologies for Advanced Petascale Simulations  

SciTech Connect

Our final report on the accomplishments of ITAPS at Stony Brook during period covered by the research award includes component service, interface service and applications. On the component service, we have designed and implemented a robust functionality for the Lagrangian tracking of dynamic interface. We have migrated the hyperbolic, parabolic and elliptic solver from stage-wise second order toward global second order schemes. We have implemented high order coupling between interface propagation and interior PDE solvers. On the interface service, we have constructed the FronTier application programer's interface (API) and its manual page using doxygen. We installed the FronTier functional interface to conform with the ITAPS specifications, especially the iMesh and iMeshP interfaces. On applications, we have implemented deposition and dissolution models with flow and implemented the two-reactant model for a more realistic precipitation at the pore level and its coupling with Darcy level model. We have continued our support to the study of fluid mixing problem for problems in inertial comfinement fusion. We have continued our support to the MHD model and its application to plasma liner implosion in fusion confinement. We have simulated a step in the reprocessing and separation of spent fuels from nuclear power plant fuel rods. We have implemented the fluid-structure interaction for 3D windmill and parachute simulations. We have continued our collaboration with PNNL, BNL, LANL, ORNL, and other SciDAC institutions.

Li, Xiaolin [SUNY at Stony Brook] [SUNY at Stony Brook

2013-01-14

134

Modeling Advance Life Support Systems  

NASA Technical Reports Server (NTRS)

Activities this summer consisted of two projects that involved computer simulation of bioregenerative life support systems for space habitats. Students in the Space Life Science Training Program (SLSTP) used the simulation, space station, to learn about relationships between humans, fish, plants, and microorganisms in a closed environment. One student complete a six week project to modify the simulation by converting the microbes from anaerobic to aerobic, and then balancing the simulation's life support system. A detailed computer simulation of a closed lunar station using bioregenerative life support was attempted, but there was not enough known about system restraints and constants in plant growth, bioreactor design for space habitats and food preparation to develop an integrated model with any confidence. Instead of a completed detailed model with broad assumptions concerning the unknown system parameters, a framework for an integrated model was outlined and work begun on plant and bioreactor simulations. The NASA sponsors and the summer Fell were satisfied with the progress made during the 10 weeks, and we have planned future cooperative work.

Pitts, Marvin; Sager, John; Loader, Coleen; Drysdale, Alan

1996-01-01

135

Pilot evaluation of an advanced hingeless rotor XY-15 simulation  

NASA Technical Reports Server (NTRS)

A piloted simulation of an advanced hingeless rotor XV-15 tilt-rotor aircraft was carried out. The evaluation was made by a pilot from NASA-Ames who had previous experience flying a simulation of the current gimballed rotor NASA/Army XV-15. It was pointed out that some modifications to the force feel system were needed in order to provide rapid force trimming during rapid maneuvers. Some additional tailoring of the SCAS system was required to achieve good nap-of-the-earth performance. Overall pilot opinion on the hingeless rotor XV-15 tilt rotor was favorable. Brief discussion on the mathematical models and the simulator configuration are presented. The maneuvers and pilot comments are given along with some engineering comments.

Mcveigh, M. A.

1977-01-01

136

The Advanced Regional Prediction System (ARPS) - A multi-scale nonhydrostatic atmospheric simulation and prediction tool. Part II: Model physics and applications  

Microsoft Academic Search

Summary In Part I of this paper series, the dynamic equations, numerical solution procedures and the parameterizations of subgrid-scale and PBL turbulence of the Advanced Regional Prediction System (ARPS) were described. The dynamic and numerical framework of the model was verified using idealized and real mountain flow cases and an idealized density current. In this Part II, we present the

M. Xue; K. K. Droegemeier; V. Wong; A. Shapiro; K. Brewster; F. Carr; D. Weber; Y. Liu; D. Wang

2001-01-01

137

VORPAL - a multidimensional code for simulating advanced acceleration concepts  

Microsoft Academic Search

VORPAL is a new simulation code under development for simulation of advanced acceleration concepts such as laser wake field acceleration. VORPAL makes use of object oriented programming techniques to achieve greater flexibility and extensibility. For example, with VORPAL, one can set the physical dimension of the simulation at run time rather than compile time. This allows the user to simulate

C. Nieter; J. R. Cary

2001-01-01

138

AGRICULTURAL SIMULATION MODEL (AGSIM)  

EPA Science Inventory

AGSIM is a large-scale econometric simulation model of regional crop and national livestock production in the United States. The model was initially developed to analyze the aggregate economic impacts of a wide variety issues facing agriculture, such as technological change, pest...

139

A case study of verification, validation, and accreditation for advanced distributed simulation  

Microsoft Academic Search

The techniques and methodologies for verification and validation of software-based systems have arguably realized their greatest utility within the context of simulation. Advanced Distributed Simulation (ADS), a major initiative within the defense modeling and simulation community, presents a variety of challenges to the classical approaches. A case study of the development process and concomitant verification and validation activities for the

Ernest H. Page; Bradford S. Canova; John A. Tufarolo

1997-01-01

140

Naval threat countermeasure simulator and the IR_CRUISE_missiles models for the generation of infrared (IR) videos of maritime targets and background for input into advanced imaging IR seekers  

NASA Astrophysics Data System (ADS)

A new hardware-in-the-loop modeling technique was developed at the US Naval Research Laboratory (NRL) for the evaluation of IR countermeasures against advanced IR imaging anti-ship cruise missiles. The research efforts involved the creation of tools to generate accurate IR imagery and synthesize video to inject in to real-world threat simulators. A validation study was conducted to verify the accuracy and limitations of the techniques that were developed.

Taczak, Thomas M.; Dries, John W.; Gover, Robert E.; Snapp, Mary Ann; Williams, Elmer F.; Cahill, Colin P.

2002-07-01

141

Recent advances in atomic modeling  

SciTech Connect

Precision spectroscopy of solar plasmas has historically been the goad for advances in calculating the atomic physics and dynamics of highly ionized atoms. Recent efforts to understand the laboratory plasmas associated with magnetic and inertial confinement fusion, and with X-ray laser research, have played a similar role. Developments spurred by laboratory plasma research are applicable to the modeling of high-resolution spectra from both solar and cosmic X-ray sources, such as the photoionized plasmas associated with accretion disks. Three of these developments in large scale atomic modeling are reviewed: a new method for calculating large arrays of collisional excitation rates, a sum rule based method for extending collisional-radiative models and modeling the effects of autoionizing resonances, and a detailed level accounting calculation of resonant excitation rates in FeXVII. 21 refs., 5 figs., 2 tabs.

Goldstein, W.H.

1988-10-12

142

Precision Casting via Advanced Simulation and Manufacturing  

NASA Technical Reports Server (NTRS)

A two-year program was conducted to develop and commercially implement selected casting manufacturing technologies to enable significant reductions in the costs of castings, increase the complexity and dimensional accuracy of castings, and reduce the development times for delivery of high quality castings. The industry-led R&D project was cost shared with NASA's Aerospace Industry Technology Program (AITP). The Rocketdyne Division of Boeing North American, Inc. served as the team lead with participation from Lockheed Martin, Ford Motor Company, Howmet Corporation, PCC Airfoils, General Electric, UES, Inc., University of Alabama, Auburn University, Robinson, Inc., Aracor, and NASA-LeRC. The technical effort was organized into four distinct tasks. The accomplishments reported herein. Task 1.0 developed advanced simulation technology for core molding. Ford headed up this task. On this program, a specialized core machine was designed and built. Task 2.0 focused on intelligent process control for precision core molding. Howmet led this effort. The primary focus of these experimental efforts was to characterize the process parameters that have a strong impact on dimensional control issues of injection molded cores during their fabrication. Task 3.0 developed and applied rapid prototyping to produce near net shape castings. Rocketdyne was responsible for this task. CAD files were generated using reverse engineering, rapid prototype patterns were fabricated using SLS and SLA, and castings produced and evaluated. Task 4.0 was aimed at developing technology transfer. Rocketdyne coordinated this task. Casting related technology, explored and evaluated in the first three tasks of this program, was implemented into manufacturing processes.

1997-01-01

143

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS  

SciTech Connect

High-Resolution Source Parameters using Calibration from Ambient Seismic Noise (ASN) Zhongwen Zhan, Shengji Wei, Sidao Ni, and Don V. Helmberger Abstract Several new methods have been developed to retrieve local Green's functions based on the cross-correlation of ambient seismic noise (station-to-station) and conventional (source-to-station) inversions. The latter methods provide the most broadband results but require accurate source parameters for phase-delay recovery which depends on the starting model. Considerable progress is being made in providing such information from 3D modeling, Tape et al. (2008), using Adjoint Tomography. But to match waveforms for the recent Chino Hills event still requires shifting synthetics to align on data. This means that it is difficult to use 3D simulations to refine source locations in near-real time. We can avoid the 3D problems by applying the CAP method and storing shifts from past events, Tan (2006), and/or using ASN, Shapiro et al. (2005), to predict lags for surface waves. Here, we directly compare results from CAP predictions with ASN results using stations near the Chino Hills event. We use the same SC seismic model as used in the Library of Earthquakes to generate Green's functions for noise (single force) for comparison with ASN correlations and allow Cap delays. We apply these delays or corrections to determine precise Centroid locations.

Helmberger, Donald V.; Tromp, Jeroen; Rodgers, Arthur J.

2009-04-30

144

A hybrid optimization-mesoscopic simulation dynamic traffic assignment model  

Microsoft Academic Search

The evaluation of ITS measures, such as advanced traveler information systems and advanced traffic management systems depend heavily on the use of faster than real time traffic simulation methods. Although many micro-simulation traffic models have already been developed, their execution times are still too slow for large-scale ITS applications. This has lead to the development of mesoscopic simulation and traffic

Michael Florian; Michael Mahut; Nicolas Tremblay

2001-01-01

145

A Virtual Engineering Framework for Simulating Advanced Power System  

SciTech Connect

In this report is described the work effort performed to provide NETL with VE-Suite based Virtual Engineering software and enhanced equipment models to support NETL's Advanced Process Engineering Co-simulation (APECS) framework for advanced power generation systems. Enhancements to the software framework facilitated an important link between APECS and the virtual engineering capabilities provided by VE-Suite (e.g., equipment and process visualization, information assimilation). Model enhancements focused on improving predictions for the performance of entrained flow coal gasifiers and important auxiliary equipment (e.g., Air Separation Units) used in coal gasification systems. In addition, a Reduced Order Model generation tool and software to provide a coupling between APECS/AspenPlus and the GE GateCycle simulation system were developed. CAPE-Open model interfaces were employed where needed. The improved simulation capability is demonstrated on selected test problems. As part of the project an Advisory Panel was formed to provide guidance on the issues on which to focus the work effort. The Advisory Panel included experts from industry and academics in gasification, CO2 capture issues, process simulation and representatives from technology developers and the electric utility industry. To optimize the benefit to NETL, REI coordinated its efforts with NETL and NETL funded projects at Iowa State University, Carnegie Mellon University and ANSYS/Fluent, Inc. The improved simulation capabilities incorporated into APECS will enable researchers and engineers to better understand the interactions of different equipment components, identify weaknesses and processes needing improvement and thereby allow more efficient, less expensive plants to be developed and brought on-line faster and in a more cost-effective manner. These enhancements to APECS represent an important step toward having a fully integrated environment for performing plant simulation and engineering. Furthermore, with little effort the modeling capabilities described in this report can be extended to support other DOE programs, such as ultra super critical boiler development, oxy-combustion boiler development or modifications to existing plants to include CO2 capture and sequestration.

Mike Bockelie; Dave Swensen; Martin Denison; Stanislav Borodai

2008-06-18

146

Advancements in engineering turbulence modeling  

NASA Technical Reports Server (NTRS)

Some new developments in two-equation models and second order closure models are presented. Two-equation models (k-epsilon models) have been widely used in computational fluid dynamics (CFD) for engineering problems. Most of low-Reynolds number two-equation models contain some wall-distance damping functions to account for the effect of wall on turbulence. However, this often causes the confusion and difficulties in computing flows with complex geometry and also needs an ad hoc treatment near the separation and reattachment points. A set of modified two-equation models is proposed to remove the aforementioned shortcomings. The calculations using various two-equation models are compared with direct numerical simulations of channel flow and flat boundary layers. Development of a second order closure model is also discussed with emphasis on the modeling of pressure related correlation terms and dissipation rates in the second moment equations. All the existing models poorly predict the normal stresses near the wall and fail to predict the 3-D effect of mean flow on the turbulence (e.g. decrease in the shear stress caused by the cross flow in the boundary layer). The newly developed second order near-wall turbulence model is described and is capable of capturing the near-wall behavior of turbulence as well as the effect of 3-D mean flow on the turbulence.

Shih, T.-H.

1991-01-01

147

New Developments in the Simulation of Advanced Accelerator Concepts  

SciTech Connect

Improved computational methods are essential to the diverse and rapidly developing field of advanced accelerator concepts. We present an overview of some computational algorithms for laser-plasma concepts and high-brightness photocathode electron sources. In particular, we discuss algorithms for reduced laser-plasma models that can be orders of magnitude faster than their higher-fidelity counterparts, as well as important on-going efforts to include relevant additional physics that has been previously neglected. As an example of the former, we present 2D laser wakefield accelerator simulations in an optimal Lorentz frame, demonstrating>10 GeV energy gain of externally injected electrons over a 2 m interaction length, showing good agreement with predictions from scaled simulations and theory, with a speedup factor of ~;;2,000 as compared to standard particle-in-cell.

Paul, K.; Cary, J.R.; Cowan, B.; Bruhwiler, D.L.; Geddes, C.G.R.; Mullowney, P.J.; Messmer, P.; Esarey, E.; Cormier-Michel, E.; Leemans, W.P.; Vay, J.-L.

2008-09-10

148

Overview of LMCT's advanced ladar signal simulator (ALASS)  

NASA Astrophysics Data System (ADS)

The Advanced Ladar Signal Simulator (ALASS) is a comprehensive laser radar simulator that synthesizes ladar signals for complex three dimensional dynamic diffuse targets in the presence of a dynamic turbulent atmosphere. ALASS provides single realization random signals (speckle) or the associated mean signals (ensemble rough target average). ALASS is radiometrically correct, accurately models receiver diffraction and defocus for both coherent and direct detection transceivers with single or multi-element detectors, and generates signals with correct three dimensional speckle statistics. Signals are computed using the target plane formulism; for coherent detection this involves the calculation of the back propagated local oscillator (BPLO) while for direct detection the back propagated impulse response (BPIR) is used. ALASS's primary functions are to serve as a laser radar sensor design tool, data product generator for exploitation, and a decision aid for implementing system designs. This paper provides an overview of ALASS, describes its functionality, presents validation results, and displays example imagery.

Jacob, Don; Gatt, Phillip; Nichols, Terry

2008-05-01

149

Rotor systems research aircraft simulation mathematical model  

NASA Technical Reports Server (NTRS)

An analytical model developed for evaluating and verifying advanced rotor concepts is discussed. The model was used during in both open loop and real time man-in-the-loop simulation during the rotor systems research aircraft design. Future applications include: pilot training, preflight of test programs, and the evaluation of promising concepts before their implementation on the flight vehicle.

Houck, J. A.; Moore, F. L.; Howlett, J. J.; Pollock, K. S.; Browne, M. M.

1977-01-01

150

Advanced Modeling of Micromirror Devices  

NASA Technical Reports Server (NTRS)

The flexure-beam micromirror device (FBMD) is a phase only piston style spatial light modulator demonstrating properties which can be used for phase adaptive corrective optics. This paper presents a complete study of a square FBMD, from advanced model development through final device testing and model verification. The model relates the electrical and mechanical properties of the device by equating the electrostatic force of a parallel-plate capacitor with the counter-acting spring force of the device's support flexures. The capacitor solution is derived via the Schwartz-Christoffel transformation such that the final solution accounts for non-ideal electric fields. The complete model describes the behavior of any piston-style device, given its design geometry and material properties. It includes operational parameters such as drive frequency and temperature, as well as fringing effects, mirror surface deformations, and cross-talk from neighboring devices. The steps taken to develop this model can be applied to other micromirrors, such as the cantilever and torsion-beam designs, to produce an advanced model for any given device. The micromirror devices studied in this paper were commercially fabricated in a surface micromachining process. A microscope-based laser interferometer is used to test the device in which a beam reflected from the device modulates a fixed reference beam. The mirror displacement is determined from the relative phase which generates a continuous set of data for each selected position on the mirror surface. Plots of this data describe the localized deflection as a function of drive voltage.

Michalicek, M. Adrian; Sene, Darren E.; Bright, Victor M.

1995-01-01

151

Brush seal numerical simulation: Concepts and advances  

NASA Technical Reports Server (NTRS)

The development of the brush seal is considered to be most promising among the advanced type seals that are presently in use in the high speed turbomachinery. The brush is usually mounted on the stationary portions of the engine and has direct contact with the rotating element, in the process of limiting the 'unwanted' leakage flows between stages, or various engine cavities. This type of sealing technology is providing high (in comparison with conventional seals) pressure drops due mainly to the high packing density (around 100 bristles/sq mm), and brush compliance with the rotor motions. In the design of modern aerospace turbomachinery leakage flows between the stages must be minimal, thus contributing to the higher efficiency of the engine. Use of the brush seal instead of the labyrinth seal reduces the leakage flow by one order of magnitude. Brush seals also have been found to enhance dynamic performance, cost less, and are lighter than labyrinth seals. Even though industrial brush seals have been successfully developed through extensive experimentation, there is no comprehensive numerical methodology for the design or prediction of their performance. The existing analytical/numerical approaches are based on bulk flow models and do not allow the investigation of the effects of brush morphology (bristle arrangement), or brushes arrangement (number of brushes, spacing between them), on the pressure drops and flow leakage. An increase in the brush seal efficiency is clearly a complex problem that is closely related to the brush geometry and arrangement, and can be solved most likely only by means of a numerically distributed model.

Braun, M. J.; Kudriavtsev, V. V.

1994-01-01

152

Modeling and simulation  

Microsoft Academic Search

Modeling and simulation (M&S) represents a fundamental change in the US Department of Defense (DOD), and has been identified as a critical technology that allows evaluation, testing, and training without building physical replicas. Although M&S can never replace actual hardware tests and exercises, savings come from testing borderline performance conditions with no risk to the hardware or human life. The

1992-01-01

153

Modelling and simulation in polymer and composites processing  

Microsoft Academic Search

The general theme of this special section is modelling and simulation in polymer and composite processing. Composite processing in general involves reactive processing. During the last decade there have been numerous advances in modelling and simulation in both thermoplastic and reactive processing. This fact, coupled with the enormous advances in computing capability, has made Computer Aided Engineering (CAE) a reality.

José M Castro

2004-01-01

154

EDITORIAL: Modelling and simulation in polymer and composites processing  

Microsoft Academic Search

The general theme of this special section is modelling and simulation in polymer and composite processing. Composite processing in general involves reactive processing. During the last decade there have been numerous advances in modelling and simulation in both thermoplastic and reactive processing. This fact, coupled with the enormous advances in computing capability, has made Computer Aided Engineering (CAE) a reality.

Josè M. Castro

2004-01-01

155

Agent-based Modeling and Simulation  

Microsoft Academic Search

Agent-based modeling and simulation (ABMS) is a new approach to modeling systems comprised of autonomous, interacting agents. Computational advances have made possible a growing number of agent-based models across a variety of application domains. Applications range from modeling agent behavior in the stock market, supply chains, and consumer markets, to predicting the spread of epidemics, mitigating the threat of bio-warfare,

Charles M. Macal; Michael J. North

2009-01-01

156

Air-to-Air Missile Testing Using Advanced Distributed Simulation.  

National Technical Information Service (NTIS)

The Joint Advanced Distributed Simulation Joint Test and Evaluation (JADS JT&E) was chartered by the Deputy Director, Test, Systems Engineering and Evaluation (Test and Evaluation), Office of the Under Secretary of Defense (Acquisition and Technology) in ...

L. McKee

1996-01-01

157

Interim Service ISDN Satellite (ISIS) simulator development for advanced satellite designs and experiments  

NASA Technical Reports Server (NTRS)

The simulation development associated with the network models of both the Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) and the Full Service ISDN Satellite (FSIS) architectures is documented. The ISIS Network Model design represents satellite systems like the Advanced Communications Technology Satellite (ACTS) orbiting switch. The FSIS architecture, the ultimate aim of this element of the Satellite Communications Applications Research (SCAR) Program, moves all control and switching functions on-board the next generation ISDN communications satellite. The technical and operational parameters for the advanced ISDN communications satellite design will be obtained from the simulation of ISIS and FSIS engineering software models for their major subsystems. Discrete event simulation experiments will be performed with these models using various traffic scenarios, design parameters, and operational procedures. The data from these simulations will be used to determine the engineering parameters for the advanced ISDN communications satellite.

Pepin, Gerard R.

1992-01-01

158

PRATHAM: Parallel Thermal Hydraulics Simulations using Advanced Mesoscopic Methods  

SciTech Connect

At the Oak Ridge National Laboratory, efforts are under way to develop a 3D, parallel LBM code called PRATHAM (PaRAllel Thermal Hydraulic simulations using Advanced Mesoscopic Methods) to demonstrate the accuracy and scalability of LBM for turbulent flow simulations in nuclear applications. The code has been developed using FORTRAN-90, and parallelized using the message passing interface MPI library. Silo library is used to compact and write the data files, and VisIt visualization software is used to post-process the simulation data in parallel. Both the single relaxation time (SRT) and multi relaxation time (MRT) LBM schemes have been implemented in PRATHAM. To capture turbulence without prohibitively increasing the grid resolution requirements, an LES approach [5] is adopted allowing large scale eddies to be numerically resolved while modeling the smaller (subgrid) eddies. In this work, a Smagorinsky model has been used, which modifies the fluid viscosity by an additional eddy viscosity depending on the magnitude of the rate-of-strain tensor. In LBM, this is achieved by locally varying the relaxation time of the fluid.

Joshi, Abhijit S [ORNL; Jain, Prashant K [ORNL; Mudrich, Jaime A [ORNL; Popov, Emilian L [ORNL

2012-01-01

159

Gyrokinetic particle simulation model  

SciTech Connect

A new type of particle simulation model based on the gyrophase-averaged Vlasov and Poisson equations is presented. The reduced system, in which particle gyrations are removed from the equations of motion while the finite Larmor radius effects are still preserved, is most suitable for studying low frequency microinstabilities in magnetized plasmas. It is feasible to simulate an elongated system (L/sub parallel/ >> L/sub perpendicular/) with a three-dimensional grid using the present model without resorting to the usual mode expansion technique, since there is essentially no restriction on the size of ..delta..x/sub parallel/ in a gyrokinetic plasma. The new approach also enables us to further separate the time and spatial scales of the simulation from those associated with global transport through the use of multiple spatial scale expansion. Thus, the model can be a very efficient tool for studying anomalous transport problems related to steady-state drift-wave turbulence in magnetic confinement devices. It can also be applied to other areas of plasma physics.

Lee, W.W.

1986-07-01

160

Revolutions in energy through modeling and simulation  

SciTech Connect

The development and application of energy technologies for all aspects from generation to storage have improved dramatically with the advent of advanced computational tools, particularly modeling and simulation. Modeling and simulation are not new to energy technology development, and have been used extensively ever since the first commercial computers were available. However, recent advances in computing power and access have broadened the extent and use, and, through increased fidelity (i.e., accuracy) of the models due to greatly enhanced computing power, the increased reliance on modeling and simulation has shifted the balance point between modeling and experimentation. The complex nature of energy technologies has motivated researchers to use these tools to understand better performance, reliability and cost issues related to energy. The tools originated in sciences such as the strength of materials (nuclear reactor containment vessels); physics, heat transfer and fluid flow (oil production); chemistry, physics, and electronics (photovoltaics); and geosciences and fluid flow (oil exploration and reservoir storage). Other tools include mathematics, such as statistics, for assessing project risks. This paper describes a few advancements made possible by these tools and explores the benefits and costs of their use, particularly as they relate to the acceleration of energy technology development. The computational complexity ranges from basic spreadsheets to complex numerical simulations using hardware ranging from personal computers (PCs) to Cray computers. In all cases, the benefits of using modeling and simulation relate to lower risks, accelerated technology development, or lower cost projects.

Tatro, M.; Woodard, J.

1998-08-01

161

Advanced Techniques for Simulating the Behavior of Sand  

NASA Astrophysics Data System (ADS)

Computer graphics and visualization techniques continue to provide untapped research opportunities, particularly when working with earth science disciplines. Through collaboration with the Oregon Space Grant and IGERT Ecosystem Informatics programs we are developing new techniques for simulating sand. In addition, through collaboration with the Oregon Space Grant, we’ve been communicating with the Jet Propulsion Laboratory (JPL) to exchange ideas and gain feedback on our work. More specifically, JPL’s DARTS Laboratory specializes in planetary vehicle simulation, such as the Mars rovers. This simulation utilizes a virtual "sand box" to test how planetary rovers respond to different terrains while traversing them. Unfortunately, this simulation is unable to fully mimic the harsh, sandy environments of those found on Mars. Ideally, these simulations should allow a rover to interact with the sand beneath it, particularly for different sand granularities and densities. In particular, there may be situations where a rover may become stuck in sand due to lack of friction between the sand and wheels. In fact, in May 2009, the Spirit rover became stuck in the Martian sand and has provided additional motivation for this research. In order to develop a new sand simulation model, high performance computing will play a very important role in this work. More specifically, graphics processing units (GPUs) are useful due to their ability to run general purpose algorithms and ability to perform massively parallel computations. In prior research, simulating vast quantities of sand has been difficult to compute in real-time due to the computational complexity of many colliding particles. With the use of GPUs however, each particle collision will be parallelized, allowing for a dramatic performance increase. In addition, spatial partitioning will also provide a speed boost as this will help limit the number of particle collision calculations. However, since the goal of this research is to simulate the look and behavior of sand, this work will go beyond simple particle collision. In particular, we can continue to use our parallel algorithms not only on single particles but on particle “clumps” that consist of multiple combined particles. Since sand is typically not spherical in nature, these particle “clumps” help to simulate the coarse nature of sand. In a simulation environment, multiple combined particles could be used to simulate the polygonal and granular nature of sand grains. Thus, a diversity of sand particles can be generated. The interaction between these particles can then be parallelized using GPU hardware. As such, this research will investigate different graphics and physics techniques and determine the tradeoffs in performance and visual quality for sand simulation. An enhanced sand model through the use of high performance computing and GPUs has great potential to impact research for both earth and space scientists. Interaction with JPL has provided an opportunity for us to refine our simulation techniques that can ultimately be used for their vehicle simulator. As an added benefit of this work, advancements in simulating sand can also benefit scientists here on earth, especially in regard to understanding landslides and debris flows.

Clothier, M.; Bailey, M.

2009-12-01

162

Advanced Simulation Capability for Environmental Management (ASCEM): Early Site Demonstration  

SciTech Connect

The U.S. Department of Energy Office of Environmental Management, Technology Innovation and Development (EM-32), is supporting development of the Advanced Simulation Capability for Environmental Management (ASCEM). ASCEM is a state-of-the-art scientific tool and approach for understanding and predicting contaminant fate and transport in natural and engineered systems. The modular and open source high performance computing tool will facilitate integrated approaches to modeling and site characterization that enable robust and standardized assessments of performance and risk for EM cleanup and closure activities. As part of the initial development process, a series of demonstrations were defined to test ASCEM components and provide feedback to developers, engage end users in applications, and lead to an outcome that would benefit the sites. The demonstration was implemented for a sub-region of the Savannah River Site General Separations Area that includes the F-Area Seepage Basins. The physical domain included the unsaturated and saturated zones in the vicinity of the seepage basins and Fourmile Branch, using an unstructured mesh fit to the hydrostratigraphy and topography of the site. The calculations modeled variably saturated flow and the resulting flow field was used in simulations of the advection of non-reactive species and the reactive-transport of uranium. As part of the demonstrations, a new set of data management, visualization, and uncertainty quantification tools were developed to analyze simulation results and existing site data. These new tools can be used to provide summary statistics, including information on which simulation parameters were most important in the prediction of uncertainty and to visualize the relationships between model input and output.

Meza, Juan; Hubbard, Susan; Freshley, Mark D.; Gorton, Ian; Moulton, David; Denham, Miles E.

2011-03-07

163

An Advanced Scattered Moonlight Model  

NASA Astrophysics Data System (ADS)

In the current era of precision astronomy, a complete sky background model is crucial, especially as the telescopes become even larger in the next decade. Such a model is needed for planning observations as well as understanding and correcting the data for the sky background. We have developed a sky model for this purpose, and it is the most complete and universal sky model that we know of to date (Noll et al. 2012). It covers a wide range of wavelengths from 0.3 to 30 microns up to a resolution of 1,000,000 and is instrument independent. Currently it is optimized for the telescopes at Cerro Paranal and the future site Cerro Armazones in Chile. Its original purpose was to improve the ESO (European Southern Observatory) ETC (Exposure Time Calculator) used for predicting exposure times of observations with a given signal to noise ratio for a set of conditions, as part of the Austrian ascension to ESO. Improving the ETC allows for better scheduling and telescope efficiency, and our new sky model has already been implemented by ESO.The brightest natural source of optical light at night is the Moon, and it is the major contributor to the astronomical sky background. We have an improved scattered moonlight model (Jones et al. 2013), where all of the components are computed with physical processes or observational data with less empirical parametrizations. This model is spectroscopic from 0.3 to 2.5 microns and was studied with a FORS1 (Patat et al. 2008) and dedicated X-Shooter data set. To our knowledge, this is the first spectroscopic model extending into the infrared. It includes fully 3-D single and double scattering calculations with extrapolations to higher orders (Noll et al. 2012), a complex treatment for aerosol scattering (Jones et al. 2013), and a lunar fit based on the ROLO survey (Kieffer & Stone 2005). In addition to its original astronomical purpose, since the model is more physical, we can use the scattered moonlight to probe the properties of the atmosphere, such as the distribution of aerosols.We present the current status of the advanced scattered moonlight model as well as its performance in the optical and near-infrared.

Jones, Amy; Noll, Stefan; Kausch, Wolfgang; Kimeswenger, Stefan

2014-06-01

164

Brush Seal Numerical Simulation: Concepts and Advances.  

National Technical Information Service (NTIS)

The development of the brush seal is considered to be most promising among the advanced type seals that are presently in use in the high speed turbomachinery. The brush is usually mounted on the stationary portions of the engine and has direct contact wit...

M. J. Braun V. V. Kudriavtsev

1994-01-01

165

Onyx-Advanced Aeropropulsion Simulation Framework Created.  

National Technical Information Service (NTIS)

The Numerical Propulsion System Simulation (NPSS) project at the NASA Glenn Research Center is developing a new software environment for analyzing and designing aircraft engines and, eventually, space transportation systems. Its purpose is to dramatically...

J. A. Reed

2001-01-01

166

Advanced power plant training simulator for VVER-440\\/V230 nuclear power plants  

Microsoft Academic Search

An advanced, workstation based, nuclear power plant simulator has been developed for use in training the operational staff of the Bohunice Nuclear Power Plant. This training simulator uses state-of- the-art computer hardware and software and provides the capability to simultaneously include six members of the power plant operating staff in the training sessions. A detailed reactor model has been developed,

W. Shier; R. Kennett; E. Vaclav; A. Gieci

1996-01-01

167

An Advanced Visualization System For Planetary Dynamo Simulations  

Microsoft Academic Search

A major problem for modern four dimensional computational simulations is that they generate large volumes of data at a much faster rate than can be effectively processed using standard storage and visualization techniques. We are in the process of building an advanced system for interactive, real-time visualization of the output from computational planetary dynamo simulations. The dynamo code is a

M. Heimpel; P. Boulanger; C. Badke; F. Al-Shamali; J. Aurnou

2002-01-01

168

Simulation Model of a Twin-Tail, High Performance Airplane.  

National Technical Information Service (NTIS)

The mathematical model and associated computer program to simulate a twin-tailed high performance fighter airplane (McDonnell Douglas F/A-18) are described. The simulation program is written in the Advanced Continuous Simulation Language. The simulation m...

C. S. Buttrill P. D. Arbuckle K. D. Hoffler

1992-01-01

169

Models, Simulations, and Games: A Survey.  

ERIC Educational Resources Information Center

A Rand evaluation of activity and products of gaming, model-building, and simulation carried out under the auspices of the Defense Advanced Research Projects Agency aimed not only to assess the usefulness of gaming in military-political policymaking, but also to contribute to the definition of common standards and the refinement of objectives for…

Shubik, Martin; Brewer, Garry D.

170

Graphical simulation environments for modelling and simulation of integrative physiology.  

PubMed

Guyton's original integrative physiology model was a milestone in integrative physiology, combining significant physiological knowledge with an engineering perspective to develop a computational diagrammatic model. It is still used in research and teaching, with a small number of variants on the model also in circulation. However, though new research has added significantly to the knowledge represented by Guyton's model, and significant advances have been made in computing and simulation software, an accepted common platform to integrate this new knowledge has not emerged. This paper discusses the issues in the selection of a suitable platform, together with a number of current possibilities, and suggests a graphical computing environment for modelling and simulation. By way of example, a validated version of Guyton's 1992 model, implemented in the ubiquitous Simulink environment, is presented which provides a hierarchical representation amenable to extension and suitable for teaching and research uses. It is designed to appeal to the biomedical engineer and physiologist alike. PMID:20576310

Mangourova, Violeta; Ringwood, John; Van Vliet, Bruce

2011-06-01

171

New advances for wedding optimization and simulation  

Microsoft Academic Search

Many real world problems in optimization are too complexto be given tractable mathematical formulations. Multiplenonlinearities, combinatorial relationships and uncertaintiesoften render challenging practical problems inaccessible tomodeling except by resorting to simulation -- an outcomethat poses grave difficulties for classical optimizationmethods. In such situations, recourse is commonly made toitemizing a series of scenarios in the hope that at least onewill give an

Fred Glover; James P. Kelly; Manuel Laguna

1999-01-01

172

Micromechanical modeling of advanced materials  

SciTech Connect

Funded as a laboratory-directed research and development (LDRD) project, the work reported here focuses on the development of a computational methodology to determine the dynamic response of heterogeneous solids on the basis of their composition and microstructural morphology. Using the solid dynamics wavecode CTH, material response is simulated on a scale sufficiently fine to explicitly represent the material`s microstructure. Conducting {open_quotes}numerical experiments{close_quotes} on this scale, the authors explore the influence that the microstructure exerts on the material`s overall response. These results are used in the development of constitutive models that take into account the effects of microstructure without explicit representation of its features. Applying this methodology to a glass-reinforced plastic (GRP) composite, the authors examined the influence of various aspects of the composite`s microstructure on its response in a loading regime typical of impact and penetration. As a prerequisite to the microscale modeling effort, they conducted extensive materials testing on the constituents, S-2 glass and epoxy resin (UF-3283), obtaining the first Hugoniot and spall data for these materials. The results of this work are used in the development of constitutive models for GRP materials in transient-dynamics computer wavecodes.

Silling, S.A.; Taylor, P.A.; Wise, J.L.; Furnish, M.D.

1994-04-01

173

Advances in Sun-Earth Connection Modeling  

NASA Astrophysics Data System (ADS)

Space weather forecasting is a focus of a multidisciplinary research effort motivated by a sensitive dependence of many modern technologies on geospace conditions. Adequate understanding of the physics of the Sun-Earth connection and associated multi-scale magnetospheric and ionospheric processes is an essential part of this effort. Modern physical simulation models such as multimoment multifluid models with effective coupling from small-scale kinetic processes can provide valuable insight into the role of various physical mechanisms operating during geomagnetic storm/substorm activity. However, due to necessary simplifying assumptions, physical models are still not well suited for accurate real-time forecasting. Complimentary approach includes data-driven models capable of efficient processing of multi-scale spatio-temporal data. However, the majority of advanced nonlinear algorithms, including neural networks (NN), can encounter a set of problems called dimensionality curse when applied to high-dimensional data. Forecasting of rare/extreme events such as large geomagnetic storms/substorms is of the most practical importance but is also very challenging for many existing models. A very promising algorithm that combines the power of the best nonlinear techniques and tolerance to high-dimensional and incomplete data is support vector machine (SVM). We have summarized advantages of the SVM and described a hybrid model based on SVM and extreme value theory (EVT) for rare event forecasting. Results of the SVM application to substorm forecasting and future directions are discussed.

Ganguli, S. B.; Gavrishchaka, V. V.

2003-06-01

174

Advanced power plant training simulator for VVER-440/V230 nuclear power plants  

SciTech Connect

An advanced, workstation based, nuclear power plant simulator has been developed for use in training the operational staff of the Bohunice Nuclear Power Plant. This training simulator uses state-of- the-art computer hardware and software and provides the capability to simultaneously include six members of the power plant operating staff in the training sessions. A detailed reactor model has been developed, representing the Bohunice VVER-44O/V230 plants, for use with the RELAP5 simulation software. In addition, a comprehensive validation program has been completed that compares the simulation results of the advanced simulator with the results from a current VVER-44O/V230 simulator. A summary of the training features and capabilities of the simulator is also provided.

Shier, W.; Kennett, R. [Brookhaven National Lab., Upton, NY (United States); Vaclav, E.; Gieci, A. [Nuclear Power Research Inst. Trnava, Inc. (Slovakia)

1996-11-01

175

PC-based Simulator for Education in Advanced Nuclear Power Plant Construction  

Microsoft Academic Search

The PC-based reactor simulation software PCTRAN was recently expanded to cover light water advanced reactors. The plant models include Generation III+ advanced PWR and BWR. The evolutionary designs are Areva EPR and GE ABWR by adding cooling path redundancy and devises for severe accident mitigation. One-step further is the passive-cooled Westinghouse AP1000 and GE ESBWR. Combined with PCTRAN's models of

Li-chi Cliff Po; Navajo Court

2008-01-01

176

State of the Art Assessment of Simulation in Advanced Materials Development  

NASA Technical Reports Server (NTRS)

Advances in both the underlying theory and in the practical implementation of molecular modeling techniques have increased their value in the advanced materials development process. The objective is to accelerate the maturation of emerging materials by tightly integrating modeling with the other critical processes: synthesis, processing, and characterization. The aims of this report are to summarize the state of the art of existing modeling tools and to highlight a number of areas in which additional development is required. In an effort to maintain focus and limit length, this survey is restricted to classical simulation techniques including molecular dynamics and Monte Carlo simulations.

Wise, Kristopher E.

2008-01-01

177

Analysis of dependencies in advanced transaction models  

Microsoft Academic Search

Transactional dependencies play an important role in coordinating and executing the subtransactions in advanced transaction\\u000a processing models, such as, nested transactions and workflow transactions. Researchers have formalized the notion of transactional\\u000a dependencies and have shown how various advanced transaction models can be expressed using different kinds of dependencies.\\u000a Incorrect specification of dependencies can result in unpredictable behavior of the advanced

Indrakshi Ray; Tai Xin

2006-01-01

178

A survey of Existing V&V, UQ and M&S Data and Knowledge Bases in Support of the Nuclear Energy - Knowledge base for Advanced Modeling and Simulation (NE-KAMS)  

SciTech Connect

The Nuclear Energy - Knowledge base for Advanced Modeling and Simulation (NE-KAMS) is being developed at the Idaho National Laboratory in conjunction with Bettis Laboratory, Sandia National Laboratories, Argonne National Laboratory, Oak Ridge National Laboratory, Utah State University and others. The objective of this consortium is to establish a comprehensive knowledge base to provide Verification and Validation (V&V) and Uncertainty Quantification (UQ) and other resources for advanced modeling and simulation (M&S) in nuclear reactor design and analysis. NE-KAMS will become a valuable resource for the nuclear industry, the national laboratories, the U.S. NRC and the public to help ensure the safe operation of existing and future nuclear reactors. A survey and evaluation of the state-of-the-art of existing V&V and M&S databases, including the Department of Energy and commercial databases, has been performed to ensure that the NE-KAMS effort will not be duplicating existing resources and capabilities and to assess the scope of the effort required to develop and implement NE-KAMS. The survey and evaluation have indeed highlighted the unique set of value-added functionality and services that NE-KAMS will provide to its users. Additionally, the survey has helped develop a better understanding of the architecture and functionality of these data and knowledge bases that can be used to leverage the development of NE-KAMS.

Hyung Lee; Rich Johnson, Ph.D.; Kimberlyn C. Moussesau

2011-12-01

179

Software tool for advanced Monte Carlo simulation of electron scattering in EBL and SEM: CHARIOT  

Microsoft Academic Search

An advanced Monte Carlo model and software were developed to simulate electron scattering in electron beam lithography and signal formation in scanning electron microscopy at a new level of accuracy required for lithography and metrology. The model involves generation of fast secondary and slow secondary electrons, as well as generation of volume plasmons, and electron transfer between layers with regard

Sergey V. Babin; S. Borisov; E. Cheremukhin; Eugene Grachev; V. Korol; L. E. Ocola

2003-01-01

180

Using CONFIG for Simulation of Operation of Water Recovery Subsystems for Advanced Control Software Evaluation  

NASA Technical Reports Server (NTRS)

A hybrid discrete/continuous simulation tool, CONFIG, has been developed to support evaluation of the operability life support systems. CON FIG simulates operations scenarios in which flows and pressures change continuously while system reconfigurations occur as discrete events. In simulations, intelligent control software can interact dynamically with hardware system models. CONFIG simulations have been used to evaluate control software and intelligent agents for automating life support systems operations. A CON FIG model of an advanced biological water recovery system has been developed to interact with intelligent control software that is being used in a water system test at NASA Johnson Space Center

Malin, Jane T.; Flores, Luis; Fleming, Land; Throop, Daiv

2002-01-01

181

Time parallelization of advanced operation scenario simulations of ITER plasma  

NASA Astrophysics Data System (ADS)

This work demonstrates that simulations of advanced burning plasma operation scenarios can be successfully parallelized in time using the parareal algorithm. CORSICA -an advanced operation scenario code for tokamak plasmas is used as a test case. This is a unique application since the parareal algorithm has so far been applied to relatively much simpler systems except for the case of turbulence. In the present application, a computational gain of an order of magnitude has been achieved which is extremely promising. A successful implementation of the Parareal algorithm to codes like CORSICA ushers in the possibility of time efficient simulations of ITER plasmas.

Samaddar, D.; Casper, T. A.; Kim, S. H.; Berry, L. A.; Elwasif, W. R.; Batchelor, D.; Houlberg, W. A.

2013-02-01

182

An Advanced Coarse-Grained Nucleosome Core Particle Model for Computer Simulations of Nucleosome-Nucleosome Interactions under Varying Ionic Conditions  

PubMed Central

In the eukaryotic cell nucleus, DNA exists as chromatin, a compact but dynamic complex with histone proteins. The first level of DNA organization is the linear array of nucleosome core particles (NCPs). The NCP is a well-defined complex of 147 bp DNA with an octamer of histones. Interactions between NCPs are of paramount importance for higher levels of chromatin compaction. The polyelectrolyte nature of the NCP implies that nucleosome-nucleosome interactions must exhibit a great influence from both the ionic environment as well as the positively charged and highly flexible N-terminal histone tails, protruding out from the NCP. The large size of the system precludes a modelling analysis of chromatin at an all-atom level and calls for coarse-grained approximations. Here, a model of the NCP that include the globular histone core and the flexible histone tails described by one particle per each amino acid and taking into account their net charge is proposed. DNA wrapped around the histone core was approximated at the level of two base pairs represented by one bead (bases and sugar) plus four beads of charged phosphate groups. Computer simulations, using a Langevin thermostat, in a dielectric continuum with explicit monovalent (K+), divalent (Mg2+) or trivalent (Co(NH3)63+) cations were performed for systems with one or ten NCPs. Increase of the counterion charge results in a switch from repulsive NCP-NCP interaction in the presence of K+, to partial aggregation with Mg2+ and to strong mutual attraction of all 10 NCPs in the presence of CoHex3+. The new model reproduced experimental results and the structure of the NCP-NCP contacts is in agreement with available data. Cation screening, ion-ion correlations and tail bridging contribute to the NCP-NCP attraction and the new NCP model accounts for these interactions.

Fan, Yanping; Korolev, Nikolay; Lyubartsev, Alexander P.; Nordenskiold, Lars

2013-01-01

183

Advances in discrete element modelling of underground excavations  

Microsoft Academic Search

The paper presents advances in the discrete element modelling of underground excavation processes extending modelling possibilities\\u000a as well as increasing computational efficiency. Efficient numerical models have been obtained using techniques of parallel\\u000a computing and coupling the discrete element method with finite element method. The discrete element algorithm has been applied\\u000a to simulation of different excavation processes, using different tools, TBMs

Carlos Labra; Jerzy Rojek; Eugenio Oñate; Francisco Zarate

2008-01-01

184

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS  

SciTech Connect

Earthquake source parameters underpin several aspects of nuclear explosion monitoring. Such aspects are: calibration of moment magnitudes (including coda magnitudes) and magnitude and distance amplitude corrections (MDAC); source depths; discrimination by isotropic moment tensor components; and waveform modeling for structure (including waveform tomography). This project seeks to improve methods for and broaden the applicability of estimating source parameters from broadband waveforms using the Cut-and-Paste (CAP) methodology. The CAP method uses a library of Green’s functions for a one-dimensional (1D, depth-varying) seismic velocity model. The method separates the main arrivals of the regional waveform into 5 windows: Pnl (vertical and radial components), Rayleigh (vertical and radial components) and Love (transverse component). Source parameters are estimated by grid search over strike, dip, rake and depth and seismic moment or equivalently moment magnitude, MW, are adjusted to fit the amplitudes. Key to the CAP method is allowing the synthetic seismograms to shift in time relative to the data in order to account for path-propagation errors (delays) in the 1D seismic velocity model used to compute the Green’s functions. The CAP method has been shown to improve estimates of source parameters, especially when delay and amplitude biases are calibrated using high signal-to-noise data from moderate earthquakes, CAP+.

Helmberger, Donald V.; Tromp, Jeroen; Rodgers, Arthur J.

2008-06-17

185

High-Fidelity Simulation for Advanced Cardiac Life Support Training  

PubMed Central

Objective. To determine whether a high-fidelity simulation technique compared with lecture would produce greater improvement in advanced cardiac life support (ACLS) knowledge, confidence, and overall satisfaction with the training method. Design. This sequential, parallel-group, crossover trial randomized students into 2 groups distinguished by the sequence of teaching technique delivered for ACLS instruction (ie, classroom lecture vs high-fidelity simulation exercise). Assessment. Test scores on a written examination administered at baseline and after each teaching technique improved significantly from baseline in all groups but were highest when lecture was followed by simulation. Simulation was associated with a greater degree of overall student satisfaction compared with lecture. Participation in a simulation exercise did not improve pharmacy students’ knowledge of ACLS more than attending a lecture, but it was associated with improved student confidence in skills and satisfaction with learning and application. Conclusions. College curricula should incorporate simulation to complement but not replace lecture for ACLS education.

Davis, Lindsay E.; Storjohann, Tara D.; Spiegel, Jacqueline J.; Beiber, Kellie M.

2013-01-01

186

Analytical and simulator study of advanced transport  

NASA Technical Reports Server (NTRS)

An analytic methodology, based on the optimal-control pilot model, was demonstrated for assessing longitidunal-axis handling qualities of transport aircraft in final approach. Calibration of the methodology is largely in terms of closed-loop performance requirements, rather than specific vehicle response characteristics, and is based on a combination of published criteria, pilot preferences, physical limitations, and engineering judgment. Six longitudinal-axis approach configurations were studied covering a range of handling qualities problems, including the presence of flexible aircraft modes. The analytical procedure was used to obtain predictions of Cooper-Harper ratings, a solar quadratic performance index, and rms excursions of important system variables.

Levison, W. H.; Rickard, W. W.

1982-01-01

187

ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS  

SciTech Connect

This quarter, we have focused on several tasks: (1) Building a high-quality catalog of earthquake source parameters for the Middle East and East Asia. In East Asia, we computed source parameters using the CAP method for a set of events studied by Herrman et al., (MRR, 2006) using a complete waveform technique. Results indicated excellent agreement with the moment magnitudes in the range 3.5 -5.5. Below magnitude 3.5 the scatter increases. For events with more than 2-3 observations at different azimuths, we found good agreement of focal mechanisms. Depths were generally consistent, although differences of up to 10 km were found. These results suggest that CAP modeling provides estimates of source parameters at least as reliable as complete waveform modeling techniques. However, East Asia and the Yellow Sea Korean Paraplatform (YSKP) region studied are relatively laterally homogeneous and may not benefit from the CAP method’s flexibility to shift waveform segments to account for path-dependent model errors. A more challenging region to study is the Middle East where strong variations in sedimentary basin, crustal thickness and crustal and mantle seismic velocities greatly impact regional wave propagation. We applied the CAP method to a set of events in and around Iran and found good agreement between estimated focal mechanisms and those reported by the Global Centroid Moment Tensor (CMT) catalog. We found a possible bias in the moment magnitudes that may be due to the thick low-velocity crust in the Iranian Plateau. (2) Testing Methods on a Lifetime Regional Data Set. In particular, the recent 2/21/08 Nevada Event and Aftershock Sequence occurred in the middle of USArray, producing over a thousand records per event. The tectonic setting is quite similar to Central Iran and thus provides an excellent testbed for CAP+ at ranges out to 10°, including extensive observations of crustal thinning and thickening and various Pnl complexities. Broadband modeling in 1D, 2D, and 3D will be presented. (3) Shallow Crustal Structure and Sparse Network Source Inversions for Southern California. We conducted a detailed test of a recently developed technique, CAPloc, in recovering source parameters including location and depth based on tomographic maps. We tested two-station solutions against 160 well determined events which worked well except for paths crossing deep basins and along mountain ridges.

Helmberger, Donald V.; Tromp, Jeroen; Rodgers, Arthur J.

2008-10-17

188

Advanced Simulation and Computing National Code Strategy. Simulation-Based Complex Transformation.  

National Technical Information Service (NTIS)

The Integrated Codes (IC) program element plays a key role in the success of the Advanced Simulation and Computing (ASC) Campaign and the Science-Based Stockpile Stewardship Program (SSP). Stockpile stewardship encompasses a broad range of activities to e...

K. Alvin N. Frazier R. Mesiner

2009-01-01

189

Advances in Modelling of Valley Glaciers  

NASA Astrophysics Data System (ADS)

For glaciological conditions typical of valley glaciers, the central idea of this research lies in understanding the effects of high-order mechanics and parameterizing these for simpler dynamical and statistical methods in glaciology. As an effective tool for this, I formulate a new brand of dynamical models that describes distinct physical processes of deformational flow. Through numerical simulations of idealized glacier domains, I calculate empirical correction factors to capture the effects of longitudinal stress gradients and lateral drag for simplified dynamical models in the plane-strain regime. To get some insights into real glacier dynamics, I simulate Haig Glacier in the Canadian Rocky Mountains. As geometric effects overshadow dynamical effects in glacier retreat scenarios, it appears that high-order physics are not very important for Haig Glacier, particularly for evaluating its fate. Indeed, high-order and reduced models all predict that Haig Glacier ceases to exist by about AD2080 under ongoing climate warming. This finding regarding the minimal role of high-order physics may not be broadly valid, as it is not true in advance scenarios at Haig Glacier and it may not be representative of other glaciological settings. Through a 'bulk' parameterization of high-order physics, geometric and climatic settings, sliding conditions, and transient effects, I also provide new insights into the volume-area relation, a widely used statistical method for estimating glacier volume. I find a steady-state power-law exponent of 1:46, which declines systematically to 1:38 after 100 years of sustained retreat, in good accord with the observations. I recommend more accurate scaling relations through characterization of individual glacier morphology and degree of climatic disequilibrium. This motivates a revision of global glacier volume estimates, of some urgency in sea level rise assessments.

Adhikari, Surendra

190

Advanced concepts in large-scale network simulation  

Microsoft Academic Search

This tutorial paper reviews existing concepts and future di- rections in selected areas related to simulation of large-scale networks. It covers specifically topics in traffic modeling, simulation of routing, network emulation, and real-time simulation. Use of communication networks is pervasive, and is increas- ing. The larger and more complex these networks become, the harder it is to predict their behavior

David M. Nicol; Michael Liljenstam; Jason Liu

2005-01-01

191

Advanced computer graphic techniques for laser range finder (LRF) simulation  

NASA Astrophysics Data System (ADS)

This paper show an advanced computer graphic techniques for laser range finder (LRF) simulation. The LRF is the common sensor for unmanned ground vehicle, autonomous mobile robot and security applications. The cost of the measurement system is extremely high, therefore the simulation tool is designed. The simulation gives an opportunity to execute algorithm such as the obstacle avoidance[1], slam for robot localization[2], detection of vegetation and water obstacles in surroundings of the robot chassis[3], LRF measurement in crowd of people[1]. The Axis Aligned Bounding Box (AABB) and alternative technique based on CUDA (NVIDIA Compute Unified Device Architecture) is presented.

Bedkowski, Janusz; Jankowski, Stanislaw

2008-11-01

192

PIXE simulation: Models, methods and technologies  

SciTech Connect

The simulation of PIXE (Particle Induced X-ray Emission) is discussed in the context of general-purpose Monte Carlo systems for particle transport. Dedicated PIXE codes are mainly concerned with the application of the technique to elemental analysis, but they lack the capability of dealing with complex experimental configurations. General-purpose Monte Carlo codes provide powerful tools to model the experimental environment in great detail, but so far they have provided limited functionality for PIXE simulation. This paper reviews recent developments that have endowed the Geant4 simulation toolkit with advanced capabilities for PIXE simulation, and related efforts for quantitative validation of cross sections and other physical parameters relevant to PIXE simulation.

Batic, M. [INFN Sezione di Genova, Via Dodecaneso 33, 16146 Genova, Italy and Jozef Stefan Institute, Jamova cesta 39, Ljubljana 1000 (Slovenia); Pia, M. G.; Saracco, P. [INFN Sezione di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Weidenspointner, G. [Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 Muenchen (Germany) and Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, Garching 85748 (Germany)

2013-04-19

193

Benchmark Dose Modeling - Advanced Topics - 2  

EPA Science Inventory

The objectives of this full-day course are to provide participants with training on how to use the U.S. Environmental Protection Agency’s (EPA) Benchmark Dose Modeling Software (BMDS) and related software programs to facilitate advanced BMD analyses. Advanced dose-response...

194

Interim Service ISDN Satellite (ISIS) network model for advanced satellite designs and experiments  

NASA Technical Reports Server (NTRS)

The Interim Service Integrated Services Digital Network (ISDN) Satellite (ISIS) Network Model for Advanced Satellite Designs and Experiments describes a model suitable for discrete event simulations. A top-down model design uses the Advanced Communications Technology Satellite (ACTS) as its basis. The ISDN modeling abstractions are added to permit the determination and performance for the NASA Satellite Communications Research (SCAR) Program.

Pepin, Gerard R.; Hager, E. Paul

1991-01-01

195

An introduction to simulation modeling  

Microsoft Academic Search

This paper offers an introductory overview of discrete simulation, with emphasis on the simulation modeling process rather than on any specific simulation package. Examples are used to demonstrate the application of the methodology at each step of the process. An extensive list of additional readings is given for the reader who wishes to deepen his\\/her knowledge in a specific area.

Martha A. Centeno

1996-01-01

196

Modeling and Simulation of Nuclear Fuel Materials  

SciTech Connect

We review the state of modeling and simulation of nuclear fuels with emphasis on the most widely used nuclear fuel, UO2. The hierarchical scheme presented represents a science-based approach to modeling nuclear fuels by progressively passing information in several stages from ab initio to continuum levels. Such an approach is essential to overcome the challenges posed by radioactive materials handling, experimental limitations in modeling extreme conditions and accident scenarios and small time and distance scales of fundamental defect processes. When used in conjunction with experimental validation, this multiscale modeling scheme can provide valuable guidance to development of fuel for advanced reactors to meet rising global energy demand.

Devanathan, Ram [Pacific Northwest National Laboratory (PNNL); Van Brutzel, Laurent [LSCE/CEA, Gif-sur-Yvette, France; Chartier, Alain [LSCE/CEA, Gif-sur-Yvette, France; Christine, Gueneau [LSCE/CEA, Gif-sur-Yvette, France; Mattsson, Ann [Sandia National Laboratories (SNL); Tikare, Veena [Sandia National Laboratories (SNL); Bartel, Timothy [Sandia National Laboratories (SNL); Besmann, Theodore M [ORNL; Stan, Marius [Los Alamos National Laboratory (LANL); Van Uffelen, Paul [Institute for Transuranium Elements, Germany

2010-01-01

197

Nonlinear Dynamic Models in Advanced Life Support  

NASA Technical Reports Server (NTRS)

To facilitate analysis, ALS systems are often assumed to be linear and time invariant, but they usually have important nonlinear and dynamic aspects. Nonlinear dynamic behavior can be caused by time varying inputs, changes in system parameters, nonlinear system functions, closed loop feedback delays, and limits on buffer storage or processing rates. Dynamic models are usually cataloged according to the number of state variables. The simplest dynamic models are linear, using only integration, multiplication, addition, and subtraction of the state variables. A general linear model with only two state variables can produce all the possible dynamic behavior of linear systems with many state variables, including stability, oscillation, or exponential growth and decay. Linear systems can be described using mathematical analysis. Nonlinear dynamics can be fully explored only by computer simulations of models. Unexpected behavior is produced by simple models having only two or three state variables with simple mathematical relations between them. Closed loop feedback delays are a major source of system instability. Exceeding limits on buffer storage or processing rates forces systems to change operating mode. Different equilibrium points may be reached from different initial conditions. Instead of one stable equilibrium point, the system may have several equilibrium points, oscillate at different frequencies, or even behave chaotically, depending on the system inputs and initial conditions. The frequency spectrum of an output oscillation may contain harmonics and the sums and differences of input frequencies, but it may also contain a stable limit cycle oscillation not related to input frequencies. We must investigate the nonlinear dynamic aspects of advanced life support systems to understand and counter undesirable behavior.

Jones, Harry

2002-01-01

198

Advancements in Engineering Turbulence Modeling.  

National Technical Information Service (NTIS)

Some new developments in two-equation models and second order closure models are presented. Two-equation models (k-epsilon models) have been widely used in computational fluid dynamics (CFD) for engineering problems. Most of low-Reynolds number two-equati...

T. Shih

1991-01-01

199

Advanced Modeling of Mixed Signals Systems.  

National Technical Information Service (NTIS)

This final report describes software products produced in the Advance Modeling of Mixed Signal Systems project and outlines project accomplishments. Several software tools were developed and made available. The capability developments behind the tools wer...

M. Steer

2005-01-01

200

The Mondrian Propagation Simulation Model  

Microsoft Academic Search

We present a propagation simulation model developed at TELECOM-ParisTech to assess performance of mobile radio networks. This model is consistent with the typical propagation model OSLN (one slope with log normal shadowing propagation model) considered by most authors. The new scheme, called Mondrian model, presents several interesting features: (i) it introduces correlations between powers measured on two nearby points, (ii)

Philippe Godlewski

2011-01-01

201

Simulating Traffic with Queueing Models  

Microsoft Academic Search

Abstract: Queueing models for traffic simulations are interesting models for applications. They can be used to simulate up to 10^8 cars\\/s on completely standard hard-ware. Unfortunately, uptonow, there was a catch: they sometimes show weird results, most notably jams that do not run backward. This work shows how queueing models can be made as realistic as most car-following models. Two

Nils Eissfeldt; Peter Wagner

2003-01-01

202

Montreal MAPP training simulation model  

Microsoft Academic Search

Simulation is being used in the Montreal Metropolitain Area Postal Plant (MAPP) to train operating and supervisory staff to process the mail. A simulation model developed will initially be used to train the staff for the Letter Processing Plant (LPP) at St. Laurent. With some modifications the same model would be adapted to train staff for other LPP of Canada

Muhammed Naqi

1978-01-01

203

National Research Council Dialogue to Assess Progress on NASA's Advanced Modeling, Simulation and Analysis Capability and Systems Engineering Capability Roadmap Development  

NASA Technical Reports Server (NTRS)

Contents include the following: General Background and Introduction of Capability Roadmaps. Agency Objective. Strategic Planning Transformation. Advanced Planning Organizational Roles. Public Involvement in Strategic Planning. Strategic Roadmaps and Schedule. Capability Roadmaps and Schedule. Purpose of NRC Review. Capability Roadmap Development (Progress to Date).

Aikins, Jan

2005-01-01

204

TOPICAL REVIEW: Modelling and simulation in reactive polymer processing  

Microsoft Academic Search

Modelling and simulation in reactive polymer processing have been active research areas for the past decades in academic institutions as well as within the industry. Both areas have played a key role in advancing and optimizing reactive polymer processing operations. The objective of this paper is to review the two major classifications of models used to simulate polymer processes: physics

José M. Castro; Mauricio Cabrera Ríos; Clark A. Mount-Campbell

2004-01-01

205

A future Outlook: Web based Simulation of Hydrodynamic models  

Microsoft Academic Search

Despite recent advances to present simulation results as 3D graphs or animation contours, the modeling user community still faces some shortcomings when trying to move around and analyze data. Typical problems include the lack of common platforms with standard vocabulary to exchange simulation results from different numerical models, insufficient descriptions about data (metadata), lack of robust search and retrieval tools

A. S. Islam; M. Piasecki

2003-01-01

206

Software Requirements Specification Verifiable Fuel Cycle Simulation (VISION) Model  

SciTech Connect

The purpose of this Software Requirements Specification (SRS) is to define the top-level requirements for a Verifiable Fuel Cycle Simulation Model (VISION) of the Advanced Fuel Cycle (AFC). This simulation model is intended to serve a broad systems analysis and study tool applicable to work conducted as part of the AFCI (including costs estimates) and Generation IV reactor development studies.

D. E. Shropshire; W. H. West

2005-11-01

207

Real-time simulation: The missing link in the design process of advanced grid equipment  

Microsoft Academic Search

This paper describes a design process of advanced grid equipment including both dynamic simulations and power-hardware- in-the-loop. A case study concerning the insertion of an energy storage system in a large isolated grid is used as an illustrative example. First, the methodology developed to achieve a real-time simulation of the studied grid from its original dynamic model is presented. The

Ye Wang; Gauthier Delille; Xavier Guillaud; Frédéric Colas; Bruno François

2010-01-01

208

Advanced Simulation of Coupled Earthquake and Tsunami Events (ASCETE) - Latest Simulation Techniques for Tsunami Process Studies  

NASA Astrophysics Data System (ADS)

The ASCETE project develops a simulation framework for coupled physics-based rupture generation with tsunami propagation and inundation. Recently, several new results could be achieved. Adaptive mesh tsunami propagation and inundation by discontinuous Galerkin Runge-Kutta methods allows for accurate and conservative inundation schemes. The adaptive mesh refinement allows for efficiency optimization, since computations are only performed in areas of interest and wave activity. A tree-based refinement strategy is utilized to highly optimize the code for high-performance computing architectures. Rupture simulation is performed by an unstructured tetrahedral discontinuous Galerking ADER discretization, which allows for accurate representation of complex geometries. Advanced meshing methods allow for near-realistic geometrical set-ups. Currently physically consistent state of stress and frictional strength properties inspired from seismo-thermo-mechanical models are implemented, opening the path to cutting edge process studies of earthquakes in megathrust and off-megathrust faulting systems. Code optimizations with automatic code generation tools for vector performance show gains in execution time of a factor of five and more. First results of coupled simulations with complex time-dependent rupture mechanics and correspondingly triggered tsunami events demonstrate the potential for novel process studies and uncertainty assessment of realistic events.

Behrens, Joern; Bader, Michael; Breuer, Alexander N.; Dalguer, Luis A.; Gabriel, Alice-A.; Galvez Barron, Percy E.; Pelties, Christian; Rahnema, Kaveh; Vater, Stefan

2014-05-01

209

Numerical wind speed simulation model  

SciTech Connect

A relatively simple stochastic model for simulating wind speed time series that can be used as an alternative to time series from representative locations is described in this report. The model incorporates systematic seasonal variation of the mean wind, its standard deviation, and the correlation speeds. It also incorporates systematic diurnal variation of the mean speed and standard deviation. To demonstrate the model capabilities, simulations were made using model parameters derived from data collected at the Hanford Meteorology Station, and results of analysis of simulated and actual data were compared.

Ramsdell, J.V.; Athey, G.F.; Ballinger, M.Y.

1981-09-01

210

Requirements for advanced simulation of nuclear reactor and chemicalseparation plants.  

SciTech Connect

This report presents requirements for advanced simulation of nuclear reactor and chemical processing plants that are of interest to the Global Nuclear Energy Partnership (GNEP) initiative. Justification for advanced simulation and some examples of grand challenges that will benefit from it are provided. An integrated software tool that has its main components, whenever possible based on first principles, is proposed as possible future approach for dealing with the complex problems linked to the simulation of nuclear reactor and chemical processing plants. The main benefits that are associated with a better integrated simulation have been identified as: a reduction of design margins, a decrease of the number of experiments in support of the design process, a shortening of the developmental design cycle, and a better understanding of the physical phenomena and the related underlying fundamental processes. For each component of the proposed integrated software tool, background information, functional requirements, current tools and approach, and proposed future approaches have been provided. Whenever possible, current uncertainties have been quoted and existing limitations have been presented. Desired target accuracies with associated benefits to the different aspects of the nuclear reactor and chemical processing plants were also given. In many cases the possible gains associated with a better simulation have been identified, quantified, and translated into economical benefits.

Palmiotti, G.; Cahalan, J.; Pfeiffer, P.; Sofu, T.; Taiwo, T.; Wei,T.; Yacout, A.; Yang, W.; Siegel, A.; Insepov, Z.; Anitescu, M.; Hovland,P.; Pereira, C.; Regalbuto, M.; Copple, J.; Willamson, M.

2006-12-11

211

Integrating advanced materials simulation techniques into an automated data analysis workflow at the Spallation Neutron Source  

SciTech Connect

This presentation will review developments on the integration of advanced modeling and simulation techniques into the analysis step of experimental data obtained at the Spallation Neutron Source. A workflow framework for the purpose of refining molecular mechanics force-fields against quasi-elastic neutron scattering data is presented. The workflow combines software components to submit model simulations to remote high performance computers, a message broker interface for communications between the optimizer engine and the simulation production step, and tools to convolve the simulated data with the experimental resolution. A test application shows the correction to a popular fixed-charge water model in order to account polarization effects due to the presence of solvated ions. Future enhancements to the refinement workflow are discussed. This work is funded through the DOE Center for Accelerating Materials Modeling.

Borreguero Calvo, Jose M [ORNL] [ORNL; Campbell, Stuart I [ORNL] [ORNL; Delaire, Olivier A [ORNL] [ORNL; Doucet, Mathieu [ORNL] [ORNL; Goswami, Monojoy [ORNL] [ORNL; Hagen, Mark E [ORNL] [ORNL; Lynch, Vickie E [ORNL] [ORNL; Proffen, Thomas E [ORNL] [ORNL; Ren, Shelly [ORNL] [ORNL; Savici, Andrei T [ORNL] [ORNL; Sumpter, Bobby G [ORNL] [ORNL

2014-01-01

212

Nanorobot: Modelling and Simulation  

Microsoft Academic Search

This research addresses the state of the art in nanorobot design and simulation focusing on the leukemia disease as well as ongoing applications on addressing the challenges posed by cancer treatment, especially chemotherapy. Nanotechnology and cancer biology, along with a new concept to leukemia treatment are the basis for nanorobot design. Robot architecture consists of Body, Ultrasonic Sensors, Folate material

Arosha Senanayake; R. G. Sirisinghe; Phang Shih Mun

2007-01-01

213

Automatic programming of simulation models  

NASA Technical Reports Server (NTRS)

The objective of automatic programming is to improve the overall environment for describing the program. This improved environment is realized by a reduction in the amount of detail that the programmer needs to know and is exposed to. Furthermore, this improved environment is achieved by a specification language that is more natural to the user's problem domain and to the user's way of thinking and looking at the problem. The goal of this research is to apply the concepts of automatic programming (AP) to modeling discrete event simulation system. Specific emphasis is on the design and development of simulation tools to assist the modeler define or construct a model of the system and to then automatically write the corresponding simulation code in the target simulation language, GPSS/PC. A related goal is to evaluate the feasibility of various languages for constructing automatic programming simulation tools.

Schroer, Bernard J.; Tseng, Fan T.; Zhang, Shou X.; Dwan, Wen S.

1988-01-01

214

Improving F-15C Air Combat Training with Distributed Mission Training (DMT) Advanced Simulation.  

National Technical Information Service (NTIS)

Air Combat Command is investing in Distributed Mission Training (DMT) to provide realistic mission training to the Combat Air Forces (CAF) using advances in simulation technology. DMT will network advanced simulators (and some real-world systems) to provi...

K. A. Seaman

1999-01-01

215

Advances in sediment transport modelling  

Microsoft Academic Search

A detailed description of how recently-developed sediment dynamics formulations are incorporated into the United States Environmental Protection Agency's Environmental Fluid Dynamics Code is presented. The new approach is an extension of previous models and accounts for multiple sediment size classes, has a unified treatment of suspended load and bedload, and appropriately replicates bed armouring. The resulting flow, transport, and sediment

Scott C. James; Craig A. Jones; Matthew D. Grace; Jesse D. Roberts

2010-01-01

216

Model Standards Advance the Profession  

ERIC Educational Resources Information Center

Leadership by teachers is essential to serving the needs of students, schools, and the teaching profession. To that end, the Teacher Leadership Exploratory Consortium has developed Teacher Leader Model Standards to codify, promote, and support teacher leadership as a vehicle to transform schools for the needs of the 21st century. The Teacher…

Journal of Staff Development, 2011

2011-01-01

217

Advanced Numerical Modeling of Turbulent Atmospheric Flows  

NASA Astrophysics Data System (ADS)

The present chapter introduces the method of computational simulation to predict and study turbulent atmospheric flows. This includes a description of the fundamental approach to computational simulation and the practical implementation using the technique of large-eddy simulation. In addition, selected contributions from IPA scientists to computational model development and various examples for applications are given. These examples include homogeneous turbulence, convective boundary layers, heated forest canopy, buoyant thermals, and large-scale flows with baroclinic wave instability.

Kühnlein, Christian; Dörnbrack, Andreas; Gerz, Thomas

218

An Improved ASW Simulation Model.  

National Technical Information Service (NTIS)

Previous research demonstrated conclusively that significant improvements could be realized in existing ASW simulation models with the use of variance reduction schemes and improved random number generation procedures. Included in the report is a descript...

E. J. McGrath D. Feldman J. D. Wilson

1974-01-01

219

Validation process of simulation model.  

National Technical Information Service (NTIS)

It is presented a methodology on empirical about any detailed simulation model. This kind of validation it is always related with an experimental case. The empirical validation has a residual sense, because the conclusions are based on comparison between ...

M. J. San Isidro Pindado

1997-01-01

220

Container Stuffing Simulation Model (SIMCON).  

National Technical Information Service (NTIS)

The simulation model characterizes the operations of a cargo terminal that loads cargo into ocean going containers; it is oriented toward container freight stations operated by the Military Traffic Management Command (MTMC). General input data to the mode...

1974-01-01

221

Advances in POST2 End-to-End Descent and Landing Simulation for the ALHAT Project  

NASA Technical Reports Server (NTRS)

Program to Optimize Simulated Trajectories II (POST2) is used as a basis for an end-to-end descent and landing trajectory simulation that is essential in determining design and integration capability and system performance of the lunar descent and landing system and environment models for the Autonomous Landing and Hazard Avoidance Technology (ALHAT) project. The POST2 simulation provides a six degree-of-freedom capability necessary to test, design and operate a descent and landing system for successful lunar landing. This paper presents advances in the development and model-implementation of the POST2 simulation, as well as preliminary system performance analysis, used for the testing and evaluation of ALHAT project system models.

Davis, Jody L.; Striepe, Scott A.; Maddock, Robert W.; Hines, Glenn D.; Paschall, Stephen, II; Cohanim, Babak E.; Fill, Thomas; Johnson, Michael C.; Bishop, Robert H.; DeMars, Kyle J.; Sostaric, Ronald r.; Johnson, Andrew E.

2008-01-01

222

Ballistic limit evaluation of advanced shielding using numerical simulations  

Microsoft Academic Search

The advanced shielding concept employed for the Columbus module of the International Space Station consists of an aluminum bumper and an intermediate shield of Nextel and Kevlar-epoxy. Until recently, the lack of adequate material models for the Nextel cloth and Kevlar-epoxy has precluded the practical usage of hydrocodes in evaluating the response of these shields to hypervelocity impact threats. Recently

Colin J. Hayhurst; Iain H. G. Livingstone; Richard A. Clegg; Roberto Destefanis; Moreno Faraud

2001-01-01

223

Aircraft Maintenance Effectiveness Simulation (AMES) Model.  

National Technical Information Service (NTIS)

This report covers a project to develop and test a functional simulation model of aircraft maintenance. The model is called AMES, which means Aircraft Maintenance Effectiveness Simulation. AMES is a computer model that simulates the operation and maintena...

D. Gold B. Kleine F. Fuchs S. Ravo K. Inaba

1980-01-01

224

Observation simulation experiments with regional prediction models  

NASA Technical Reports Server (NTRS)

Research efforts in FY 1990 included studies employing regional scale numerical models as aids in evaluating potential contributions of specific satellite observing systems (current and future) to numerical prediction. One study involves Observing System Simulation Experiments (OSSEs) which mimic operational initialization/forecast cycles but incorporate simulated Advanced Microwave Sounding Unit (AMSU) radiances as input data. The objective of this and related studies is to anticipate the potential value of data from these satellite systems, and develop applications of remotely sensed data for the benefit of short range forecasts. Techniques are also being used that rely on numerical model-based synthetic satellite radiances to interpret the information content of various types of remotely sensed image and sounding products. With this approach, evolution of simulated channel radiance image features can be directly interpreted in terms of the atmospheric dynamical processes depicted by a model. Progress is being made in a study using the internal consistency of a regional prediction model to simplify the assessment of forced diabatic heating and moisture initialization in reducing model spinup times. Techniques for model initialization are being examined, with focus on implications for potential applications of remote microwave observations, including AMSU and Special Sensor Microwave Imager (SSM/I), in shortening model spinup time for regional prediction.

Diak, George; Perkey, Donald J.; Kalb, Michael; Robertson, Franklin R.; Jedlovec, Gary

1990-01-01

225

Advanced visualization technology for terascale particle accelerator simulations  

Microsoft Academic Search

This paper presents two new hardware-assisted rendering techniques developed for interactive visualization of the terascale data generated from numerical modeling of next-generation accelerator designs. The first technique, based on a hybrid rendering approach, makes possible interactive exploration of large-scale particle data from particle beam dynamics modeling. The second technique, based on a compact texture-enhanced representation, exploits the advanced features of

Kwan-Liu Ma; Gregory L. Schussman; Brett Wilson; Kwok Ko; Ji Qiang; Robert Ryne

2002-01-01

226

Recent advances in modeling stellar interiors  

NASA Astrophysics Data System (ADS)

Advances in stellar interior modeling are being driven by new data from large-scale surveys and high-precision photometric and spectroscopic observations. Here we focus on single stars in normal evolutionary phases; we will not discuss the many advances in modeling star formation, interacting binaries, supernovae, or neutron stars. We review briefly: (1) updates to input physics of stellar models; (2) progress in two and three-dimensional evolution and hydrodynamic models; (3) insights from oscillation data used to infer stellar interior structure and validate model predictions (asteroseismology). We close by highlighting a few outstanding problems, e.g., the driving mechanisms for hybrid ? Dor/ ? Sct star pulsations, the cause of giant eruptions seen in luminous blue variables such as ? Car and P Cyg, and the solar abundance problem.

Guzik, Joyce Ann

2011-11-01

227

Recent advances in modeling stellar interiors (u)  

SciTech Connect

Advances in stellar interior modeling are being driven by new data from large-scale surveys and high-precision photometric and spectroscopic observations. Here we focus on single stars in normal evolutionary phases; we will not discuss the many advances in modeling star formation, interacting binaries, supernovae, or neutron stars. We review briefly: (1) updates to input physics of stellar models; (2) progress in two and three-dimensional evolution and hydrodynamic models; (3) insights from oscillation data used to infer stellar interior structure and validate model predictions (asteroseismology). We close by highlighting a few outstanding problems, e.g., the driving mechanisms for hybrid {gamma} Dor/{delta} Sct star pulsations, the cause of giant eruptions seen in luminous blue variables such as {eta} Car and P Cyg, and the solar abundance problem.

Guzik, Joyce Ann [Los Alamos National Laboratory

2010-01-01

228

Numerical field model simulation of full-scale fire tests in a closed spherical\\/cylindrical vessel using advanced computer graphics techniques  

Microsoft Academic Search

Personnel and equipment casualties, caused by shipboard fires, have adversely affected overall readiness of the U.S. Navy for centuries. Understanding the phenomena of fire in enclosed spaces, such as those found on surface ships and submarines, will greatly enhance the Navy's ability to combat or prevent them. This computer model was developed for use in conjunction with Fire-1, an experimental

Timothy G. McCarthy

1991-01-01

229

Ocean Circulation and Climate Advanced Modeling Project  

NSDL National Science Digital Library

The Ocean Circulation and Climate Advanced Modeling Project (OCCAM) uses a primitive equation numerical model to develop several high resolution visualizations of the world's oceans, including the Arctic Ocean and marginal seas such as the Mediterranean. This site features a selection of animation sequences and Quicktime movies from the model at Ã, 1/8, and 1/12 degree resolutions. Data from the model may also be requested, and after being prepared off-line, users can collect the data via ftp. The site also includes model details and parameters, an explanation of data assimilation methods, and links to publications and related projects.

Centre, Southampton O.; Council, University O.

230

Advances in scientific balloon thermal modeling  

NASA Astrophysics Data System (ADS)

The National Aeronautics and Space Administration's Balloon Program Office has long acknowledged that the accurate modeling of balloon performance and flight prediction is dependant on how well the balloon is thermally modeled. This ongoing effort is focused on developing accurate balloon thermal models that can be used to quickly predict balloon temperatures and balloon performance. The ability to model parametric changes is also a driver for this effort. This paper will present the most recent advances made in this area. This research effort continues to utilize the ``Thermal Desktop'' addition to AUTO CAD for the modeling. Recent advances have been made by using this analytical tool. A number of analyses have been completed to test the applicability of this tool to the problem with very positive results. Progressively detailed models have been developed to explore the capabilities of the tool as well as to provide guidance in model formulation. A number of parametric studies have been completed. These studies have varied the shape of the structure, material properties, environmental inputs, and model geometry. These studies have concentrated on spherical ``proxy models'' for the initial development stages and then to transition to the natural shaped zero pressure and super pressure balloons. An assessment of required model resolution has also been determined. Model solutions have been cross checked with known solutions via hand calculations. The comparison of these cases will also be presented. One goal is to develop analysis guidelines and an approach for modeling balloons for both simple first order estimates and detailed full models. This paper presents the step by step advances made as part of this effort, capabilities, limitations, and the lessons learned. Also presented are the plans for further thermal modeling work.

Bohaboj, T.; Cathey, H.

231

Advances in Modeling Exploding Bridgewire Initiation  

SciTech Connect

There is great interest in applying magnetohydrodynamic (MHD) simulation techniques to the designs of electrical high explosive (HE) initiators, for the purpose of better understanding a design's sensitivities, optimizing its performance, and/or predicting its useful lifetime. Two MHD-capable LLNL codes, CALE and ALE3D, are being used to simulate the process of ohmic heating, vaporization, and plasma formation in exploding bridgewires (EBW). Initiation of the HE is simulated using Ignition & Growth reactive flow models. 1-D, 2-D and 3-D models have been constructed and studied. The models provide some intuitive explanation of the initiation process and are useful for evaluating the potential impact of identified aging mechanisms (such as the growth of intermetallic compounds or powder sintering). The end product of this work is a simulation capability for evaluating margin in proposed, modified or aged initiation system designs.

Hrousis, C A; Christensen, J S

2010-03-10

232

Using Process/CFD Co-Simulation for the Design and Analysis of Advanced Energy Systems  

SciTech Connect

In this presentation we describe the major features and capabilities of NETL’s Advanced Process Engineering Co-Simulator (APECS) and highlight its application to advanced energy systems, ranging from small fuel cell systems to commercial-scale power plants including the coal-fired, gasification-based electricity and hydrogen plant in the DOE’s $1 billion, 10-year FutureGen demonstration project. APECS is an integrated software suite which allows the process and energy industries to optimize overall plant performance with respect to complex thermal and fluid flow phenomena by combining process simulation (e.g., Aspen Plus®) with high-fidelity equipment simulations based on computational fluid dynamics (CFD) models (e.g., FLUENT®).

Zitney, S.E.

2007-04-01

233

Modeling of advanced discharges for TPX  

Microsoft Academic Search

We describe the results of the Tokamak Physics Experiment (TPX) Scenario Modeling task. We investigated the achievement of high performance advanced tokamak operating modes in TPX through current and pressure profile shaping using fast wave (FW), lower hybrid (LH), and neutral beam (NB) heating and current drive capabilities. As part of the task, the Aries-I and negative central shear (NCS)

H. E. St. John; Y. R. Lin-Liu; P. A. Politzer; S. C. Chiu; M. S. Chu; R. L. Miller; A. D. Turnbull

1995-01-01

234

EGR Distribution in Engine Cylinders Using Advanced Virtual Simulation  

SciTech Connect

Exhaust Gas Recirculation (EGR) is a well-known technology for reduction of NOx in diesel engines. With the demand for extremely low engine out NOx emissions, it is important to have a consistently balanced EGR flow to individual engine cylinders. Otherwise, the variation in the cylinders' NOx contribution to the overall engine emissions will produce unacceptable variability. This presentation will demonstrate the effective use of advanced virtual simulation in the development of a balanced EGR distribution in engine cylinders. An initial design is analyzed reflecting the variance in the EGR distribution, quantitatively and visually. Iterative virtual lab tests result in an optimized system.

Fan, Xuetong

2000-08-20

235

High Frequency Circuit Simulator: An Advanced Electromagnetic Simulation Tool for Microwave Sources  

NASA Astrophysics Data System (ADS)

High Frequency Circuit Simulator (HFCS) is developed as an advanced electromagnetic simulation tool for microwave sources, which is based on Finite Integration Technique (FIT). In this paper, the detail of the design and realization of HFCS is provided and for validation one actual Helical Slow-Wave Structure (HSWS) is fully analyzed. Convergent process is studied and the cold-test characteristics (including dispersion, coupling impedance and attenuation constant) are calculated and compared with those from MAFIA. The consistency of the results of these two simulation tools has proved the reliability and validity of HFCS.

Zhu, Xiao Fang; Yang, Zhong Hai; Li, Bin; Li, Jian Qing; Xu, Li

2009-08-01

236

Recent advances of strong-strong beam-beam simulation  

SciTech Connect

In this paper, we report on recent advances in strong-strong beam-beam simulation. Numerical methods used in the calculation of the beam-beam forces are reviewed. A new computational method to solve the Poisson equation on nonuniform grid is presented. This method reduces the computational cost by a half compared with the standard FFT based method on uniform grid. It is also more accurate than the standard method for a colliding beam with low transverse aspect ratio. In applications, we present the study of coherent modes with multi-bunch, multi-collision beam-beam interactions at RHIC. We also present the strong-strong simulation of the luminosity evolution at KEKB with and without finite crossing angle.

Qiang, Ji; Furman, Miguel A.; Ryne, Robert D.; Fischer, Wolfram; Ohmi,Kazuhito

2004-09-15

237

An Advanced Visualization System For Planetary Dynamo Simulations  

NASA Astrophysics Data System (ADS)

A major problem for modern four dimensional computational simulations is that they generate large volumes of data at a much faster rate than can be effectively processed using standard storage and visualization techniques. We are in the process of building an advanced system for interactive, real-time visualization of the output from computational planetary dynamo simulations. The dynamo code is a modified version of Magic2 (J. Wicht, Phys. Earth Planet. Int., in press, 2002). Time-scaling of typical dynamo simulations is such that it is presently feasible to observe the motion of convection and magnetic variations in the real time numerical output, similar to a laboratory experiment. The visualization system is designed to run relatively independently of the dynamo code. In particular, the system architecture allows three-dimensional rendering of scalar and vector fields to occur independently of the data production process. Thus data production delays do not cause delays in manipulation of the visual representation, such as object rotation and data queries. In fact, for truly immersive applications the display refresh rate should be on the order of 10 Hz minimum. The main components of the system are 1) the simulation program; 2) the solution server; 3) the solution formatter; and 4) the visualization program. Here the simulation program is the dynamo code. The solution server controls which data from the simulation will be processed, thus helping to solve the problem of large data volume. The solution formatter converts simulation output for further processing by the visualization program. The subsystems 1), 2) and 3), are run on a large multiprocessor shared memory parallel (SMP) machine whereas subsystem 4) may be run on a remote PC or workstation. The data transfer from the SMP machine to the PC is facilitated by data compression and a high speed link of 1 gigabits per second. This system architecture will allow us to visualize key diagnostics in the dynamo simulations in real time, which will greatly facilitate output computational efficiency and understanding of run results. The relative independence of the visualization system from the simulation code makes it amenable for future application to different computational dynamics simulation codes.

Heimpel, M.; Boulanger, P.; Badke, C.; Al-Shamali, F.; Aurnou, J.

2002-12-01

238

ADVANCED COMPUTATIONAL MODELING OF MILITARY INCINERATORS  

Microsoft Academic Search

Incineration is being used or is planned as a primary destruction technology of stockpiles of chemical warfare agents (CWA) in the United States. Computer modeling tools may play an important role in reducing the time, cost and technical risk of using incineration. A simulation workbench is being developed to assist the chemical demilitarization community. The workbench will consist of models

Martin K. Denison; Chris J. Montgomery; Adel F. Sarofim; Michael J. Bockelie; Alfred G. Webster; Robert J. Mellon

2002-01-01

239

Combustion modeling in advanced gas turbine systems  

SciTech Connect

Goal of DOE`s Advanced Turbine Systems program is to develop and commercialize ultra-high efficiency, environmentally superior, cost competitive gas turbine systems for base-load applications in utility, independent power producer, and industrial markets. Primary objective of the program here is to develop a comprehensive combustion model for advanced gas turbine combustion systems using natural gas (coal gasification or biomass fuels). The efforts included code evaluation (PCGC-3), coherent anti-Stokes Raman spectroscopy, laser Doppler anemometry, and laser-induced fluorescence.

Smoot, L.D.; Hedman, P.O.; Fletcher, T.H.; Brewster, B.S.; Kramer, S.K. [Brigham Young Univ., Provo, UT (United States). Advanced Combustion Engineering Research Center

1995-12-31

240

In-silico simulations of advanced drug delivery systems: what will the future offer?  

PubMed

This commentary enlarges on some of the topics addressed in the Position Paper "Towards more effective advanced drug delivery systems" by Crommelin and Florence (2013). Inter alia, the role of mathematical modeling and computer-assisted device design is briefly addressed in the Position Paper. This emerging and particularly promising field is considered in more depth in this commentary. In fact, in-silico simulations have become of fundamental importance in numerous scientific and related domains, allowing for a better understanding of various phenomena and for facilitated device design. The development of novel prototypes of space shuttles, nuclear power plants and automobiles are just a few examples. In-silico simulations are nowadays also well established in the field of pharmacokinetics/pharmacodynamics (PK/PD) and have become an integral part of the discovery and development process of novel drug products. Since Takeru Higuchi published his seminal equation in 1961 the use of mathematical models for the analysis and optimization of drug delivery systems in vitro has also become more and more popular. However, applying in-silico simulations for facilitated optimization of advanced drug delivery systems is not yet common practice. One of the reasons is the gap between in vitro and in vivo (PK/PD) simulations. In the future it can be expected that this gap will be closed and that computer assisted device design will play a central role in the research on, and development of advanced drug delivery systems. PMID:23867986

Siepmann, Juergen

2013-09-15

241

Surrogate Model Development for Fuels for Advanced Combustion Engines  

SciTech Connect

The fuels used in internal-combustion engines are complex mixtures of a multitude of different types of hydrocarbon species. Attempting numerical simulations of combustion of real fuels with all of the hydrocarbon species included is highly unrealistic. Thus, a surrogate model approach is generally adopted, which involves choosing a few representative hydrocarbon species whose overall behavior mimics the characteristics of the target fuel. The present study proposes surrogate models for the nine fuels for advanced combustion engines (FACE) that have been developed for studying low-emission, high-efficiency advanced diesel engine concepts. The surrogate compositions for the fuels are arrived at by simulating their distillation profiles to within a maximum absolute error of 4% using a discrete multi-component (DMC) fuel model that has been incorporated in the multi-dimensional computational fluid dynamics (CFD) code, KIVA-ERC-CHEMKIN. The simulated surrogate compositions cover the range and measured concentrations of the various hydrocarbon classes present in the fuels. The fidelity of the surrogate fuel models is judged on the basis of matching their specific gravity, lower heating value, hydrogen/carbon (H/C) ratio, cetane number, and cetane index with the measured data for all nine FACE fuels.

Anand, Krishnasamy [University of Wisconsin, Madison; Ra, youngchul [University of Wisconsin, Madison; Reitz, Rolf [University of Wisconsin; Bunting, Bruce G [ORNL

2011-01-01

242

Graphics simulation and training aids for advanced teleoperation  

NASA Technical Reports Server (NTRS)

Graphics displays can be of significant aid in accomplishing a teleoperation task throughout all three phases of off-line task analysis and planning, operator training, and online operation. In the first phase, graphics displays provide substantial aid to investigate work cell layout, motion planning with collision detection and with possible redundancy resolution, and planning for camera views. In the second phase, graphics displays can serve as very useful tools for introductory training of operators before training them on actual hardware. In the third phase, graphics displays can be used for previewing planned motions and monitoring actual motions in any desired viewing angle, or, when communication time delay prevails, for providing predictive graphics overlay on the actual camera view of the remote site to show the non-time-delayed consequences of commanded motions in real time. This paper addresses potential space applications of graphics displays in all three operational phases of advanced teleoperation. Possible applications are illustrated with techniques developed and demonstrated in the Advanced Teleoperation Laboratory at JPL. The examples described include task analysis and planning of a simulated Solar Maximum Satellite Repair task, a novel force-reflecting teleoperation simulator for operator training, and preview and predictive displays for on-line operations.

Kim, Won S.; Schenker, Paul S.; Bejczy, Antal K.

1993-01-01

243

Co-Simulation for Advanced Process Design and Optimization  

SciTech Connect

Meeting the increasing demand for clean, affordable, and secure energy is arguably the most important challenge facing the world today. Fossil fuels can play a central role in a portfolio of carbon-neutral energy options provided CO{sub 2} emissions can be dramatically reduced by capturing CO{sub 2} and storing it safely and effectively. Fossil energy industry faces the challenge of meeting aggressive design goals for next-generation power plants with CCS. Process designs will involve large, highly-integrated, and multipurpose systems with advanced equipment items with complex geometries and multiphysics. APECS is enabling software to facilitate effective integration, solution, and analysis of high-fidelity process/equipment (CFD) co-simulations. APECS helps to optimize fluid flow and related phenomena that impact overall power plant performance. APECS offers many advanced capabilities including ROMs, design optimization, parallel execution, stochastic analysis, and virtual plant co-simulations. NETL and its collaborative R&D partners are using APECS to reduce the time, cost, and technical risk of developing high-efficiency, zero-emission power plants with CCS.

Stephen E. Zitney

2009-01-01

244

Maturity Model for Advancing Smart Grid Interoperability  

SciTech Connect

Abstract—Interoperability is about the properties of devices and systems to connect and work properly. Advancing interoperability eases integration and maintenance of the resulting interconnection. This leads to faster integration, lower labor and component costs, predictability of projects and the resulting performance, and evolutionary paths for upgrade. When specifications are shared and standardized, competition and novel solutions can bring new value streams to the community of stakeholders involved. Advancing interoperability involves reaching agreement for how things join at their interfaces. The quality of the agreements and the alignment of parties involved in the agreement present challenges that are best met with process improvement techniques. The GridWise® Architecture Council (GWAC) sponsored by the United States Department of Energy is supporting an effort to use concepts from capability maturity models used in the software industry to advance interoperability of smart grid technology. An interoperability maturity model has been drafted and experience is being gained through trials on various types of projects and community efforts. This paper describes the value and objectives of maturity models, the nature of the interoperability maturity model and how it compares with other maturity models, and experiences gained with its use.

Knight, Mark; Widergren, Steven E.; Mater, J.; Montgomery, Austin

2013-10-28

245

Dihydroergosine pharmacokinetic modelling and simulation.  

PubMed

For this study of dihydroergosine pharmacokinetic modelling and simulation, the data from our paper about 3H-DHESN plasma, bile, urine, and faeces concentrations after intravenous and oral administration were used (1). The model obtained with the identified parameters was in agreement with in vivo data. Certain special phenomena, such as the enterohepatic cycle and incomplete absorption, were taken into account. Analog-hybrid simulation and identification represents an effective tool for such studies. In spite of the limited validity of the available in vivo data, the work represents a first step in the introduction of DHESN into human medicine. PMID:6861792

Karba, R; Mrhar, A; Kozjek, F; Bremsak, F; Kopitar, Z; Lenardic, A

1983-01-01

246

Using LabVIEWTM for advanced nonlinear optoelectronic device simulations in high-speed optical communications  

Microsoft Academic Search

We present an advanced and comprehensive semiconductor optical amplifier model to analyze the propagation and amplification of 10 to, in principle, 1280 Gb\\/s ultra-short optical pulse sequences. Through appropriate transformation, the partial differential propagation-rate equation problem is numerically solved in a two-dimensional grid of fine resolution. The corresponding simulator, entirely programmed in the graphical language LabVIEW, is compared to an

R. Gutiérrez-Castrejón; M. Duelk

2006-01-01

247

Advance simulation and optimization of high power lnGaN\\/GaN laser diodes  

Microsoft Academic Search

The optimization of InGaN\\/GaN multiquantum wells structure based on Si-doped GaN substrate for ?~445 nm is performed. Advance simulation for a self-consistent laser model combined with band-structure and free-carrier gain calculations is employed to study effects such as waveguiding, carrier transport and heat flux. Enhancement in output power of the optimized structure is calculated. It has been found that electron

Yogiraj M. Ranade; Muhammad Khazir; M. Y. A. Raja

2010-01-01

248

Statistics and Deterministic Simulation Models: Why Not.  

National Technical Information Service (NTIS)

First deterministic simulation models are compared with random simulation models and real-life experiments. In deterministic simulation no mathematical statistics is needed in the experimental design and in the Least Squares curve fitting to the resulting...

J. P. C. Kleijnen

1990-01-01

249

Process/equipment co-simulation for designe and analysis of advanced energy systems  

SciTech Connect

b s t r a c t The grand challenge facing the power and energy industries is the development of efficient, environmentally friendly, and affordable technologies for next-generation energy systems. To provide solutions for energy and the environment, the U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) and its research partners in industry and academia are relying increasingly on the use of sophisticated computer-aided process design and optimization tools. In this paper, we describe recent progress toward developing an Advanced Process Engineering Co-Simulator (APECS) for the high-fidelity design, analysis, and optimization of energy plants. The APECS software system combines steady-state process simulation with multiphysics-based equipment simulations, such as those based on computational fluid dynamics (CFD). These co-simulation capabilities enable design engineers to optimize overall process performance with respect to complex thermal and fluid flow phenomena arising in key plant equipment items, such as combustors, gasifiers, turbines, and carbon capture devices. In this paper we review several applications of the APECS co-simulation technology to advanced energy systems, including coal-fired energy plants with carbon capture. This paper also discusses ongoing co-simulation R&D activities and challenges in areas such as CFD-based reduced-order modeling, knowledge management, advanced analysis and optimization, and virtual plant co-simulation. Continued progress in co-simulation technology – through improved integration, solution, and deployment – will have profound positive impacts on the design and optimization of high-efficiency, near-zero emission fossil energy systems.

Zitney, S.

2010-01-01

250

Software Partitioning Schemes for Advanced Simulation Computer Systems. Final Report.  

ERIC Educational Resources Information Center

Conducted to design software partitioning techniques for use by the Air Force to partition a large flight simulator program for optimal execution on alternative configurations, this study resulted in a mathematical model which defines characteristics for an optimal partition, and a manually demonstrated partitioning algorithm design which…

Clymer, S. J.

251

ADVANCED ELECTRIC AND MAGNETIC MATERIAL MODELS FOR FDTD ELECTROMAGNETIC CODES  

SciTech Connect

The modeling of dielectric and magnetic materials in the time domain is required for pulse power applications, pulsed induction accelerators, and advanced transmission lines. For example, most induction accelerator modules require the use of magnetic materials to provide adequate Volt-sec during the acceleration pulse. These models require hysteresis and saturation to simulate the saturation wavefront in a multipulse environment. In high voltage transmission line applications such as shock or soliton lines the dielectric is operating in a highly nonlinear regime, which require nonlinear models. Simple 1-D models are developed for fast parameterization of transmission line structures. In the case of nonlinear dielectrics, a simple analytic model describing the permittivity in terms of electric field is used in a 3-D finite difference time domain code (FDTD). In the case of magnetic materials, both rate independent and rate dependent Hodgdon magnetic material models have been implemented into 3-D FDTD codes and 1-D codes.

Poole, B R; Nelson, S D; Langdon, S

2005-05-05

252

Credit Risk Modelling using Hardware Accelerated Monte-Carlo Simulation  

Microsoft Academic Search

The recent turmoil in global credit markets has demon- strated the need for advanced modelling of credit risk, which can take into account the effects of changing eco- nomic conditions on portfolios of loans. Such models are most easily described as Monte-Carlo simulations, but take too long to converge in software based simula- tors. This paper describes a hardware implementation

David B. Thomas; Wayne Luk

2008-01-01

253

International Space Station power system requirements models and simulation  

Microsoft Academic Search

International Space Station (ISS) Payload Engineering Integration (PEI) organization adopted the advanced computation and simulation technology to develop integrated electrical system models based on the test data of the various sub-units to addressing specific power system design requirements. This system model was used to assess the power system requirements for assuring: (1) Compatibility of loads with delivered power, (2) Compatibility

Henry Hoang; S. Johnny Fu

2012-01-01

254

Modeling and simulation of microturbine  

Microsoft Academic Search

In this work, modeling, simulation and analysis of load following behaviour of microturbine (MT) as a Distributed Energy Resource (DER) have been performed. The system comprises a MT interconnected to the utility grid. The MT is capable of operating in both islanded and grid-connected modes. This work considers that the MT supplies power to variable general and critical loads. The

A. K. Saha; S. Chowdhury

2010-01-01

255

Economic Analysis. Computer Simulation Models.  

ERIC Educational Resources Information Center

A multimedia course in economic analysis was developed and used in conjunction with the United States Naval Academy. (See ED 043 790 and ED 043 791 for final reports of the project evaluation and development model.) This volume of the text discusses the simulation of behavioral relationships among variable elements in an economy and presents…

Sterling Inst., Washington, DC. Educational Technology Center.

256

Specification of advanced safety modeling requirements (Rev. 0).  

SciTech Connect

The U.S. Department of Energy's Global Nuclear Energy Partnership has lead to renewed interest in liquid-metal-cooled fast reactors for the purpose of closing the nuclear fuel cycle and making more efficient use of future repository capacity. However, the U.S. has not designed or constructed a fast reactor in nearly 30 years. Accurate, high-fidelity, whole-plant dynamics safety simulations will play a crucial role by providing confidence that component and system designs will satisfy established design limits and safety margins under a wide variety of operational, design basis, and beyond design basis transient conditions. Current modeling capabilities for fast reactor safety analyses have resulted from several hundred person-years of code development effort supported by experimental validation. The broad spectrum of mechanistic and phenomenological models that have been developed represent an enormous amount of institutional knowledge that needs to be maintained. Complicating this, the existing code architectures for safety modeling evolved from programming practices of the 1970s. This has lead to monolithic applications with interdependent data models which require significant knowledge of the complexities of the entire code in order for each component to be maintained. In order to develop an advanced fast reactor safety modeling capability, the limitations of the existing code architecture must be overcome while preserving the capabilities that already exist. To accomplish this, a set of advanced safety modeling requirements is defined, based on modern programming practices, that focuses on modular development within a flexible coupling framework. An approach for integrating the existing capabilities of the SAS4A/SASSYS-1 fast reactor safety analysis code into the SHARP framework is provided in order to preserve existing capabilities while providing a smooth transition to advanced modeling capabilities. In doing this, the advanced fast reactor safety models will target leadership-class computing architectures for massively-parallel high-fidelity computations while providing continued support for rapid prototyping using modest fidelity computations on multiple-core desktop platforms.

Fanning, T. H.; Tautges, T. J.

2008-06-30

257

Advanced coal gasifier designs using large-scale simulations  

SciTech Connect

Porting of the legacy code MFIX to a high performance computer (HPC) and the use of high resolution simulations for the design of a coal gasifier are described here. MFIX is based on a continuum multiphase flow model that considers gas and solids to form interpenetrating continua. Low resolution simulations of a commercial scale gasifier with a validated MFIX model revealed interesting physical phenomena with implications on the gasifier design, which prompted the study reported here. To be predictive, the simulations need to model the spatiotemporal variations in gas and solids volume fractions, velocities, temperatures with any associated phase change and chemical reactions. These processes occur at various time- and length-scales requiring very high spatial resolution and large number of iterations with small time-steps. We were able to perform perhaps the largest known simulations of gas-solids reacting flows, providing detailed information about the gas-solids flow structure and the pressure, temperature and species distribution in the gasifier. One key finding is the new features of the coal jet trajectory revealed with the high spatial resolution, which provides information on the accuracy of the lower resolution simulations. Methodologies for effectively combining high and low resolution simulations for design studies must be developed. From a computational science perspective, we found that global communication has to be reduced to achieve scalability to 1000s of cores, hybrid parallelization is required to effectively utilize the multicore chips, and the wait time in the batch queue significantly increases the actual time-to-solution. From our experience, development is required in the following areas: efficient solvers for heterogeneous, massively parallel systems; data analysis tools to extract information from large data sets; and programming environments for easily porting legacy codes to HPC.

Syamlal, M [National Energy Technology Laboratory (NETL); Guenther, Chris [National Energy Technology Laboratory (NETL); Gel, Aytekin [Aeolus Research Inc.; Pannala, Sreekanth [ORNL

2009-01-01

258

Advanced visualization technology for terascale particle accelerator simulations  

SciTech Connect

This paper presents two new hardware-assisted rendering techniques developed for interactive visualization of the terascale data generated from numerical modeling of next generation accelerator designs. The first technique, based on a hybrid rendering approach, makes possible interactive exploration of large-scale particle data from particle beam dynamics modeling. The second technique, based on a compact texture-enhanced representation, exploits the advanced features of commodity graphics cards to achieve perceptually effective visualization of the very dense and complex electromagnetic fields produced from the modeling of reflection and transmission properties of open structures in an accelerator design. Because of the collaborative nature of the overall accelerator modeling project, the visualization technology developed is for both desktop and remote visualization settings. We have tested the techniques using both time varying particle data sets containing up to one billion particle s per time step and electromagnetic field data sets with millions of mesh elements.

Ma, K-L; Schussman, G.; Wilson, B.; Ko, K.; Qiang, J.; Ryne, R.

2002-11-16

259

New routes to advanced simulation of material forming  

NASA Astrophysics Data System (ADS)

We developed in recent years a novel technique, called Proper Generalized Decomposition (PGD), based on the assumption of a separated form of the unknown field. It has demonstrated its capabilities in dealing with highdimensional problems overcoming the strong limitations of classical approaches. Many challenging problems can be efficiently cast into a multidimensional framework. For instance, parameters in a model (loads, initial conditions, boundary conditions, material parameters, geometrical parameters,...) can be set as additional extra-coordinates of the model. In a PGD framework, the resulting model is solved once for life, in order to obtain a general solution that includes all the solutions for every possible value of the parameters, that is, a sort virtual chart. Under this rationale, optimization of complex problems, uncertainty quantification, simulation-based control and real-time simulation are now at hand, in highly complex scenarios and on deployed platforms.

Chinesta, Francisco; Leygue, Adrien; Bordeu, Felipe

2013-05-01

260

Advanced Simulation & Computing FY09-FY10 Implementation Plan Volume 2, Rev. 0  

SciTech Connect

The Stockpile Stewardship Program (SSP) is a single, highly integrated technical program for maintaining the safety and reliability of the U.S. nuclear stockpile. The SSP uses past nuclear test data along with current and future nonnuclear test data, computational modeling and simulation, and experimental facilities to advance understanding of nuclear weapons. It includes stockpile surveillance, experimental research, development and engineering programs, and an appropriately scaled production capability to support stockpile requirements. This integrated national program requires the continued use of current facilities and programs along with new experimental facilities and computational enhancements to support these programs. The Advanced Simulation and Computing Program (ASC)1 is a cornerstone of the SSP, providing simulation capabilities and computational resources to support the annual stockpile assessment and certification, to study advanced nuclear-weapons design and manufacturing processes, to analyze accident scenarios and weapons aging, and to provide the tools to enable Stockpile Life Extension Programs (SLEPs) and the resolution of Significant Finding Investigations (SFIs). This requires a balanced resource, including technical staff, hardware, simulation software, and computer science solutions. In its first decade, the ASC strategy focused on demonstrating simulation capabilities of unprecedented scale in three spatial dimensions. In its second decade, ASC is focused on increasing its predictive capabilities in a three-dimensional simulation environment while maintaining the support to the SSP. The program continues to improve its unique tools for solving progressively more difficult stockpile problems (focused on sufficient resolution, dimensionality and scientific details); to quantify critical margins and uncertainties (QMU); and to resolve increasingly difficult analyses needed for the SSP. Moreover, ASC has restructured its business model from one that was very successful in delivering an initial capability to one that is integrated and focused on requirements-driven products that address long-standing technical questions related to enhanced predictive capability in the simulation tools. ASC must continue to meet three objectives: Objective 1. Robust Tools--Develop robust models, codes, and computational techniques to support stockpile needs such as refurbishments, SFIs, LEPs, annual assessments, and evolving future requirements. Objective 2--Prediction through Simulation. Deliver validated physics and engineering tools to enable simulations of nuclear-weapons performances in a variety of operational environments and physical regimes and to enable risk-informed decisions about the performance, safety, and reliability of the stockpile. Objective 3--Balanced Operational Infrastructure. Implement a balanced computing platform acquisition strategy and operational infrastructure to meet Directed Stockpile Work (DSW) and SSP needs for capacity and high-end simulation capabilities.

Meisner, R; Perry, J; McCoy, M; Hopson, J

2008-04-30

261

Advanced Simulation and Computing Fiscal Year 2011-2012 Implementation Plan, Revision 0  

SciTech Connect

The Stockpile Stewardship Program (SSP) is a single, highly integrated technical program for maintaining the surety and reliability of the U.S. nuclear stockpile. The SSP uses past nuclear test data along with current and future non-nuclear test data, computational modeling and simulation, and experimental facilities to advance understanding of nuclear weapons. It includes stockpile surveillance, experimental research, development and engineering (D&E) programs, and an appropriately scaled production capability to support stockpile requirements. This integrated national program requires the continued use of current facilities and programs along with new experimental facilities and computational enhancements to support these programs. The Advanced Simulation and Computing Program (ASC) is a cornerstone of the SSP, providing simulation capabilities and computational resources to support the annual stockpile assessment and certification, to study advanced nuclear weapons design and manufacturing processes, to analyze accident scenarios and weapons aging, and to provide the tools to enable stockpile Life Extension Programs (LEPs) and the resolution of Significant Finding Investigations (SFIs). This requires a balanced resource, including technical staff, hardware, simulation software, and computer science solutions. In its first decade, the ASC strategy focused on demonstrating simulation capabilities of unprecedented scale in three spatial dimensions. In its second decade, ASC is focused on increasing its predictive capabilities in a three-dimensional (3D) simulation environment while maintaining support to the SSP. The program continues to improve its unique tools for solving progressively more difficult stockpile problems (focused on sufficient resolution, dimensionality and scientific details); to quantify critical margins and uncertainties (QMU); and to resolve increasingly difficult analyses needed for the SSP. Moreover, ASC has restructured its business model from one that was very successful in delivering an initial capability to one that is integrated and focused on requirements-driven products that address long-standing technical questions related to enhanced predictive capability in the simulation tools. ASC must continue to meet three objectives: Objective 1 - Robust Tools. Develop robust models, codes, and computational techniques to support stockpile needs such as refurbishments, SFIs, LEPs, annual assessments, and evolving future requirements. Objective 2 - Prediction through Simulation. Deliver validated physics and engineering tools to enable simulations of nuclear weapons performance in a variety of operational environments and physical regimes and to enable risk-informed decisions about the performance, safety, and reliability of the stockpile. Objective 3 - Balanced Operational Infrastructure. Implement a balanced computing platform acquisition strategy and operational infrastructure to meet Directed Stockpile Work (DSW) and SSP needs for capacity and high-end simulation capabilities.

McCoy, M; Phillips, J; Hpson, J; Meisner, R

2010-04-22

262

Advanced Simulation and Computing FY08-09 Implementation Plan, Volume 2, Revision 0.5  

SciTech Connect

The Stockpile Stewardship Program (SSP) is a single, highly integrated technical program for maintaining the surety and reliability of the U.S. nuclear stockpile. The SSP uses past nuclear test data along with current and future non-nuclear test data, computational modeling and simulation, and experimental facilities to advance understanding of nuclear weapons. It includes stockpile surveillance, experimental research, development and engineering programs, and an appropriately scaled production capability to support stockpile requirements. This integrated national program requires the continued use of current facilities and programs along with new experimental facilities and computational enhancements to support these programs. The Advanced Simulation and Computing Program (ASC)1 is a cornerstone of the SSP, providing simulation capabilities and computational resources to support the annual stockpile assessment and certification, to study advanced nuclear-weapons design and manufacturing processes, to analyze accident scenarios and weapons aging, and to provide the tools to enable Stockpile Life Extension Programs (SLEPs) and the resolution of Significant Finding Investigations (SFIs). This requires a balanced resource, including technical staff, hardware, simulation software, and computer science solutions. In its first decade, the ASC strategy focused on demonstrating simulation capabilities of unprecedented scale in three spatial dimensions. In its second decade, ASC is focused on increasing its predictive capabilities in a three-dimensional simulation environment while maintaining the support to the SSP. The program continues to improve its unique tools for solving progressively more difficult stockpile problems (focused on sufficient resolution, dimensionality and scientific details); to quantify critical margins and uncertainties (QMU); and to resolve increasingly difficult analyses needed for the SSP. Moreover, ASC has restructured its business model from one that was very successful in delivering an initial capability to one that is integrated and focused on requirements-driven products that address long-standing technical questions related to enhanced predictive capability in the simulation tools. ASC must continue to meet three objectives: Objective 1. Robust Tools--Develop robust models, codes, and computational techniques to support stockpile needs such as refurbishments, SFIs, LEPs, annual assessments, and evolving future requirements. Objective 2--Prediction through Simulation. Deliver validated physics and engineering tools to enable simulations of nuclear-weapons performances in a variety of operational environments and physical regimes and to enable risk-informed decisions about the performance, safety, and reliability of the stockpile. Objective 3. Balanced Operational Infrastructure--Implement a balanced computing platform acquisition strategy and operational infrastructure to meet Directed Stockpile Work (DSW) and SSP needs for capacity and high-end simulation capabilities.

Kusnezov, D; Bickel, T; McCoy, M; Hopson, J

2007-09-13

263

Advances in modeling of biomolecular interactions1  

Microsoft Academic Search

Modeling of molecular interactions is increasingly used in life science research and biotechnology development. Examples are computer aided drug design, prediction of protein interactions with other molecules, and simulation of networks of biomolecules in a particular process in human body. This article reviews recent progress in the related fields and provides a brief overview on the methods used in molecular

Cong-zhong CAI; Ze-rong LI; Wan-lu WANG; Yu-zong CHEN

264

Advanced solutions for power system analysis-computer study and real-time simulation  

Microsoft Academic Search

Successful operation of a power system depends largely on the engineer's ability to provide safe, reliable and economic service to the customer. Advanced simulation technologies provide useful means to the engineer for the design and analysis of the power system, and assisting them in making reasonable decisions. Due to powerful software and advanced real-time simulators, it became possible to simulate

B. M. Buchholz; X. Lei; D. W. Retzmann

2000-01-01

265

Modeling and Simulation for Safeguards  

SciTech Connect

The purpose of this talk is to give an overview of the role of modeling and simulation in Safeguards R&D and introduce you to (some of) the tools used. Some definitions are: (1) Modeling - the representation, often mathematical, of a process, concept, or operation of a system, often implemented by a computer program; (2) Simulation - the representation of the behavior or characteristics of one system through the use of another system, especially a computer program designed for the purpose; and (3) Safeguards - the timely detection of diversion of significant quantities of nuclear material. The role of modeling and simulation are: (1) Calculate amounts of material (plant modeling); (2) Calculate signatures of nuclear material etc. (source terms); and (3) Detector performance (radiation transport and detection). Plant modeling software (e.g. FACSIM) gives the flows and amount of material stored at all parts of the process. In safeguards this allow us to calculate the expected uncertainty of the mass and evaluate the expected MUF. We can determine the measurement accuracy required to achieve a certain performance.

Swinhoe, Martyn T. [Los Alamos National Laboratory

2012-07-26

266

Multiscale Stochastic Simulation and Modeling  

SciTech Connect

Acceleration driven instabilities of fluid mixing layers include the classical cases of Rayleigh-Taylor instability, driven by a steady acceleration and Richtmyer-Meshkov instability, driven by an impulsive acceleration. Our program starts with high resolution methods of numerical simulation of two (or more) distinct fluids, continues with analytic analysis of these solutions, and the derivation of averaged equations. A striking achievement has been the systematic agreement we obtained between simulation and experiment by using a high resolution numerical method and improved physical modeling, with surface tension. Our study is accompanies by analysis using stochastic modeling and averaged equations for the multiphase problem. We have quantified the error and uncertainty using statistical modeling methods.

James Glimm; Xiaolin Li

2006-01-10

267

Simulation and modeling of homogeneous, compressed turbulence  

NASA Technical Reports Server (NTRS)

Low Reynolds number homogeneous turbulence undergoing low Mach number isotropic and one-dimensional compression was simulated by numerically solving the Navier-Stokes equations. The numerical simulations were performed on a CYBER 205 computer using a 64 x 64 x 64 mesh. A spectral method was used for spatial differencing and the second-order Runge-Kutta method for time advancement. A variety of statistical information was extracted from the computed flow fields. These include three-dimensional energy and dissipation spectra, two-point velocity correlations, one-dimensional energy spectra, turbulent kinetic energy and its dissipation rate, integral length scales, Taylor microscales, and Kolmogorov length scale. Results from the simulated flow fields were used to test one-point closure, two-equation models. A new one-point-closure, three-equation turbulence model which accounts for the effect of compression is proposed. The new model accurately calculates four types of flows (isotropic decay, isotropic compression, one-dimensional compression, and axisymmetric expansion flows) for a wide range of strain rates.

Wu, C. T.; Ferziger, J. H.; Chapman, D. R.

1985-01-01

268

Simulation and modeling of homogeneous, compressed turbulence  

NASA Astrophysics Data System (ADS)

Low Reynolds number homogeneous turbulence undergoing low Mach number isotropic and one-dimensional compression was simulated by numerically solving the Navier-Stokes equations. The numerical simulations were performed on a CYBER 205 computer using a 64 x 64 x 64 mesh. A spectral method was used for spatial differencing and the second-order Runge-Kutta method for time advancement. A variety of statistical information was extracted from the computed flow fields. These include three-dimensional energy and dissipation spectra, two-point velocity correlations, one-dimensional energy spectra, turbulent kinetic energy and its dissipation rate, integral length scales, Taylor microscales, and Kolmogorov length scale. Results from the simulated flow fields were used to test one-point closure, two-equation models. A new one-point-closure, three-equation turbulence model which accounts for the effect of compression is proposed. The new model accurately calculates four types of flows (isotropic decay, isotropic compression, one-dimensional compression, and axisymmetric expansion flows) for a wide range of strain rates.

Wu, C. T.; Ferziger, J. H.; Chapman, D. R.

1985-05-01

269

Assessment of Molecular Modeling & Simulation  

SciTech Connect

This report reviews the development and applications of molecular and materials modeling in Europe and Japan in comparison to those in the United States. Topics covered include computational quantum chemistry, molecular simulations by molecular dynamics and Monte Carlo methods, mesoscale modeling of material domains, molecular-structure/macroscale property correlations like QSARs and QSPRs, and related information technologies like informatics and special-purpose molecular-modeling computers. The panel's findings include the following: The United States leads this field in many scientific areas. However, Canada has particular strengths in DFT methods and homogeneous catalysis; Europe in heterogeneous catalysis, mesoscale, and materials modeling; and Japan in materials modeling and special-purpose computing. Major government-industry initiatives are underway in Europe and Japan, notably in multi-scale materials modeling and in development of chemistry-capable ab-initio molecular dynamics codes.

None

2002-01-03

270

A Standard Kinematic Model for Flight Simulation at NASA Ames  

NASA Technical Reports Server (NTRS)

A standard kinematic model for aircraft simulation exists at NASA-Ames on a variety of computer systems, one of which is used to control the flight simulator for advanced aircraft (FSAA). The derivation of the kinematic model is given and various mathematical relationships are presented as a guide. These include descriptions of standardized simulation subsystems such as the atmospheric turbulence model and the generalized six-degrees-of-freedom trim routine, as well as an introduction to the emulative batch-processing system which enables this facility to optimize its real-time environment.

Mcfarland, R. E.

1975-01-01

271

Using advanced technology repositories to accelerate simulation scenario development  

NASA Astrophysics Data System (ADS)

One of the more difficult problems facing an analyst wishing to use a simulation is the task of collecting data and transforming it into a correctly formatted scenario. Raw data is often available from a variety of sources: multi-spectral force deployment (MSFD) documents, the electronic warfare integrated reprogramming database (EWIRDB), free text documents such as intelligence reports, pre-existing simulation scenarios, and scenarios taken from other simulations. The task of transforming this data into a usable scenario involves searching for the relevant information, followed by a manual transformation of the original format to the correct simulation format. This problem can be greatly alleviated by using a combination of three technologies: automatic parser generation, repository architectures using extensible markup language (XML), and information retrieval (IR) techniques. Automatic parser generation tools like JavaCC can automatically generate source code capable of reading data sources such as old Joint Integrated Mission Model (JIMM) or Suppressor input files. For simulations that regularly add scenario keywords to support changing needs, this can greatly reduce redevelopment time and cost for supporting tools. The objects parsed by this source can then be encapsulated in XML and stored into a repository. Using information retrieval techniques, objects can then be queried from the repository and transformed into the appropriate format for use in a scenario.

Trias, Eric; Mathias, Karl S.

2002-07-01

272

A Mathematical Representation of an Advanced Helicopter for Piloted Simulator Investigations of Control System and Display Variations.  

National Technical Information Service (NTIS)

A mathematical model of an advanced helicopter is described. The model is suitable for use in control/display research involving piloted simulation. The general design approach for the six degree of freedom equations of motion is to use the full set of no...

E. W. Aiken

1980-01-01

273

Simulation Framework for Teaching in Modeling and Simulation Areas  

ERIC Educational Resources Information Center

Simulation is the process of executing a model that describes a system with enough detail; this model has its entities, an internal state, some input and output variables and a list of processes bound to these variables. Teaching a simulation language such as general purpose simulation system (GPSS) is always a challenge, because of the way it…

De Giusti, Marisa Raquel; Lira, Ariel Jorge; Villarreal, Gonzalo Lujan

2008-01-01

274

Validation of GATE Monte Carlo simulations of the GE Advance/Discovery LS PET scanners  

SciTech Connect

The recently developed GATE (GEANT4 application for tomographic emission) Monte Carlo package, designed to simulate positron emission tomography (PET) and single photon emission computed tomography (SPECT) scanners, provides the ability to model and account for the effects of photon noncollinearity, off-axis detector penetration, detector size and response, positron range, photon scatter, and patient motion on the resolution and quality of PET images. The objective of this study is to validate a model within GATE of the General Electric (GE) Advance/Discovery Light Speed (LS) PET scanner. Our three-dimensional PET simulation model of the scanner consists of 12 096 detectors grouped into blocks, which are grouped into modules as per the vendor's specifications. The GATE results are compared to experimental data obtained in accordance with the National Electrical Manufactures Association/Society of Nuclear Medicine (NEMA/SNM), NEMA NU 2-1994, and NEMA NU 2-2001 protocols. The respective phantoms are also accurately modeled thus allowing us to simulate the sensitivity, scatter fraction, count rate performance, and spatial resolution. In-house software was developed to produce and analyze sinograms from the simulated data. With our model of the GE Advance/Discovery LS PET scanner, the ratio of the sensitivities with sources radially offset 0 and 10 cm from the scanner's main axis are reproduced to within 1% of measurements. Similarly, the simulated scatter fraction for the NEMA NU 2-2001 phantom agrees to within less than 3% of measured values (the measured scatter fractions are 44.8% and 40.9{+-}1.4% and the simulated scatter fraction is 43.5{+-}0.3%). The simulated count rate curves were made to match the experimental curves by using deadtimes as fit parameters. This resulted in deadtime values of 625 and 332 ns at the Block and Coincidence levels, respectively. The experimental peak true count rate of 139.0 kcps and the peak activity concentration of 21.5 kBq/cc were matched by the simulated results to within 0.5% and 0.1% respectively. The simulated count rate curves also resulted in a peak NECR of 35.2 kcps at 10.8 kBq/cc compared to 37.6 kcps at 10.0 kBq/cc from averaged experimental values. The spatial resolution of the simulated scanner matched the experimental results to within 0.2 mm.

Schmidtlein, C. Ross; Kirov, Assen S.; Nehmeh, Sadek A.; Erdi, Yusuf E.; Humm, John L.; Amols, Howard I.; Bidaut, Luc M.; Ganin, Alex; Stearns, Charles W.; McDaniel, David L.; Hamacher, Klaus A. [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, New York 10021 (United States); Department of Imaging Physics, University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, Texas 77230-1439 (United States); GE Healthcare Technologies, 3000 N. Grandview Blvd., Waukesha, Wisconsin 53188 (United States); Weill Medical College of Cornell University, 525 East 68th Street, New York, New York 10021 (United States)

2006-01-15

275

CTLSS -- An Advanced Electromagnetic Simulation Tool for Designing RF Sources  

Microsoft Academic Search

The CTLSS code is an integrated three-dimensional cold-test and large-signal simulation suite. This paper treats the 3D cold-test portion of CTLSS, which is a general-geometry, frequency-domain, electromagnetic code that handles lossy materials with very high loss tangent. CTLSS handles both resonant eigenvalue problems and non-resonant driven-frequency problems. The model supports the standard electric wall, magnetic wall, and periodic (Floquet) boundary

S. J. Cooke; R. Shtokhamer; B. Levush; A. A. Mondelli

2000-01-01

276

Time-domain analysis simulation for advanced tracking  

Microsoft Academic Search

TASAT is a complete end-to-end system simulation of tracking and pointing systems. It can currently model ground-based (GB), space-based (SB), and kinetic energy weapon (KEW) systems at a very high level of fidelity to assess system performance and design tradeoffs. It is primarily a time-domain analysis tool, but it can also perform frequency-domain analysis for performance and stability analysis. TASAT

Jim F. Riker; Gregg A. Crockett; Richard L. Brunson

1992-01-01

277

CAPE-OPEN Integration for Advanced Process Engineering Co-Simulation  

SciTech Connect

This paper highlights the use of the CAPE-OPEN (CO) standard interfaces in the Advanced Process Engineering Co-Simulator (APECS) developed at the National Energy Technology Laboratory (NETL). The APECS system uses the CO unit operation, thermodynamic, and reaction interfaces to provide its plug-and-play co-simulation capabilities, including the integration of process simulation with computational fluid dynamics (CFD) simulation. APECS also relies heavily on the use of a CO COM/CORBA bridge for running process/CFD co-simulations on multiple operating systems. For process optimization in the face of multiple and some time conflicting objectives, APECS offers stochastic modeling and multi-objective optimization capabilities developed to comply with the CO software standard. At NETL, system analysts are applying APECS to a wide variety of advanced power generation systems, ranging from small fuel cell systems to commercial-scale power plants including the coal-fired, gasification-based FutureGen power and hydrogen production plant.

Zitney, S.E.

2006-11-01

278

Advances in electromagnetic modelling through high performance computing  

NASA Astrophysics Data System (ADS)

Under the DOE SciDAC project on Accelerator Science and Technology, a suite of electromagnetic codes has been under development at SLAC that are based on unstructured grids for higher accuracy, and use parallel processing to enable large-scale simulation. The new modeling capability is supported by SciDAC collaborations on meshing, solvers, refinement, optimization and visualization. These advances in computational science are described and the application of the parallel eigensolver Omega3P to the cavity design for the International Linear Collider is discussed.

Ko, K.; Folwell, N.; Ge, L.; Guetz, A.; Lee, L.; Li, Z.; Ng, C.; Prudencio, E.; Schussman, G.; Uplenchwar, R.; Xiao, L.

2006-07-01

279

Advances in Electromagnetic Modelling through High Performance Computing  

SciTech Connect

Under the DOE SciDAC project on Accelerator Science and Technology, a suite of electromagnetic codes has been under development at SLAC that are based on unstructured grids for higher accuracy, and use parallel processing to enable large-scale simulation. The new modeling capability is supported by SciDAC collaborations on meshing, solvers, refinement, optimization and visualization. These advances in computational science are described and the application of the parallel eigensolver Omega3P to the cavity design for the International Linear Collider is discussed.

Ko, K.; Folwell, N.; Ge, L.; Guetz, A.; Lee, L.; Li, Z.; Ng, C.; Prudencio, E.; Schussman, G.; Uplenchwar, R.; Xiao, L.; /SLAC

2006-03-29

280

VISION: Verifiable Fuel Cycle Simulation Model  

SciTech Connect

The nuclear fuel cycle consists of a set of complex components that work together in unison. In order to support the nuclear renaissance, it is necessary to understand the impacts of changes and timing of events in any part of the fuel cycle system. The Advanced Fuel Cycle Initiative’s systems analysis group is developing a dynamic simulation model, VISION, to capture the relationships, timing, and changes in and among the fuel cycle components to help develop an understanding of how the overall fuel cycle works. This paper is an overview of the philosophy and development strategy behind VISION. The paper includes some descriptions of the model components and some examples of how to use VISION.

Jacob Jacobson; A. M. Yacout; Gretchen Matthern; Steven Piet; David Shropshire; Tyler Schweitzer

2010-11-01

281

Simulation Validation Through Linear Model Comparison.  

National Technical Information Service (NTIS)

The Manned Flight Simulator at the Naval Air Warfare Center in Patuxent River, MD maintains high fidelity fixed and rotary wing simulation models. The aircraft simulations are utilized for a wide range of activities including flight test support, pilot tr...

K. Balderson D. P. Gaublomme J. W. Thomas

1996-01-01

282

Estimation Model for Advance Rate in Drill and Blast Tunnelling  

Microsoft Academic Search

This paper deals with the NTNU advance rate model for drill and blast tunnelling. The estimation model for advance rate is based on round cycle time consumption, and comprises drilling, charging, blasting, ventilation, loading and hauling, scaling and rock support. The basis of the model is State-of- the-art technology and equipment with Norwegian tunnelling experience. Weekly advance rate as a

Shokrollah Zare; Amund Bruland

283

Measurement and modeling of advanced coal conversion processes  

SciTech Connect

The overall objective of this program is the development of predictive capability for the design, scale up, simulation, control and feedstock evaluation in advanced coal conversion devices. Toward this goal, work continued on the following projects: coal to char chemistry submodel; fundamental high-pressure reaction rate data; secondary reaction of pyrolysis product and burnout submodels; ash physics and chemistry submodel; large particle submodels; large char particle oxidation at high pressures; SO{sub x}--NO{sub x} submodel development; integration of advanced submodels into entrained-flow code, with evaluation and documentation; comprehensive fixed-bed modeling review, development evaluation and implementation, generalized fuels feedstock submodel; application of generalized pulverized coal comprehensive code; and application of fixed-bed code.

Soloman, P.R.; Serio, M.A.; Hamblen, D.G.; Smoot, L.D.; Brewster, B.S.

1990-01-01

284

Distributed Simulation Facility to Support Human Factors Research in Advanced Air Transportation Technology.  

National Technical Information Service (NTIS)

A distributed real-time simulation of the civil air traffic environment developed to support human factors research in advanced air transportation technology is presented. The distributed environment is based on a custom simulation architecture designed f...

K. Amonlirdviman T. C. Farley R. J. Hansman J. F. Ladik D. Z. Sherer

1998-01-01

285

Advanced Atmospheric Transport Modeling for Emergency Response  

SciTech Connect

Local and regional weather forecasts are an important component of the Department of Energy's (DOE) Savannah River Site (SRS) response capabilities in the event of hazardous accidental releases to the atmosphere. The fate of radiological or chemical releases can be determined by providing winds and turbulence input to atmospheric transport models. The Weather Information and Display (WIND) system consists of a network of computers and instruments that collect meteorological data from towers situated throughout the 800 square kilometer site, display updated results every 15 minutes, and supplies real-time data to a suite of personal computer (PC) based Gaussian dispersion models for assessing downwind hazards. It has been the primary consequence assessment tool for emergency response for many years. Several years ago, the SRS began using an advanced three-dimensional numerical model, the Regional Atmospheric Modeling System (RAMS) as a source of local forecast data for the basic WIND system models. The information RAMS provides to these dispersion models is spatially homogeneous. However, recently a more complete utilization of the spatially inhomogeneous RAMS forecasts has been realized by using a three-dimensional stochastic Lagrangian particle dispersion model (LPDM) to advect and disperse particles representing pollutant mass in the atmosphere. The purpose of this paper is to discuss the design and implementation of LPDM for use on a PC for real-time emergency response applications at the SRS.

Buckley, R.L.

2002-06-24

286

Development of Computational Approaches for Simulation and Advanced Controls for Hybrid Combustion-Gasification Chemical Looping  

SciTech Connect

This document provides the results of the project through September 2009. The Phase I project has recently been extended from September 2009 to March 2011. The project extension will begin work on Chemical Looping (CL) Prototype modeling and advanced control design exploration in preparation for a scale-up phase. The results to date include: successful development of dual loop chemical looping process models and dynamic simulation software tools, development and test of several advanced control concepts and applications for Chemical Looping transport control and investigation of several sensor concepts and establishment of two feasible sensor candidates recommended for further prototype development and controls integration. There are three sections in this summary and conclusions. Section 1 presents the project scope and objectives. Section 2 highlights the detailed accomplishments by project task area. Section 3 provides conclusions to date and recommendations for future work.

Joshi, Abhinaya; Lou, Xinsheng; Neuschaefer, Carl; Chaudry, Majid; Quinn, Joseph

2012-07-31

287

A National Strategy for Advancing Climate Modeling  

SciTech Connect

Climate models are the foundation for understanding and projecting climate and climate-related changes and are thus critical tools for supporting climate-related decision making. This study developed a holistic strategy for improving the nationâ??s capability to accurately simulate climate and related Earth system changes on decadal to centennial timescales. The committeeâ??s report is a high level analysis, providing a strategic framework to guide progress in the nationâ??s climate modeling enterprise over the next 10-20 years. This study was supported by DOE, NSF, NASA, NOAA, and the intelligence community.

Dunlea, Edward; Elfring, Chris

2012-12-04

288

Mathematical modeling and SAR simulation multifunction SAR technology efforts  

NASA Technical Reports Server (NTRS)

The orbital SAR (synthetic aperture radar) simulation data was used in several simulation efforts directed toward advanced SAR development. Efforts toward simulating an operational radar, simulation of antenna polarization effects, and simulation of SAR images at serveral different wavelengths are discussed. Avenues for improvements in the orbital SAR simulation and its application to the development of advanced digital radar data processing schemes are indicated.

Griffin, C. R.; Estes, J. M.

1981-01-01

289

BRITE II characterization and application to a new advanced flight motion simulator  

NASA Astrophysics Data System (ADS)

Hardware-in-the-loop testing has, for many years, been an integral part of the modeling and simulation efforts at the U.S. Army Aviation and Missile Command"s (AMCOM) Aviation and Missile Research, Engineering, and Development Center (AMRDEC). AMCOM"s history includes the development, characterization, and implementation of several unique technologies for the creation of synthetic environments in the visible and infrared regions and AMCOM has continued significant efforts in these areas. Recently, AMCOM has been testing and characterizing a new state-of-the-art resistor array projector and advanced flight motion simulator (FMS). This paper describes recent test and integration activities of the Honeywell BRITE II emitter array and its integration into an infrared scene projector (IRSP) compatible with a new Carco Flight Motion Simulator (FMS).

Beasley, David B.; Saylor, Daniel A.; Buford, James A., Jr.

2003-09-01

290

Advanced Modelling of Silicon Wafer Solar Cells  

NASA Astrophysics Data System (ADS)

Modelling of solar cells today is general practice in research and widely-used in industry. Established modelling software is typically limited to one dimension and/or to small scales. Additionally, novel effects, like, e.g., the use of diffractive structures or luminescent materials, are not established. In this paper we discuss how the combination of different modelling techniques can be used to overcome these limitations. In this context two examples are presented. The first example concerns the combination of the open source simulation software PC1D with circuit modelling to investigate the effect of local shunts on the global characteristics of a silicon wafer solar cell. For the investigated example (4.5 cm2 cell area) we find that a local point shunt reduces the solar cell efficiency by 4% relative. The second example concerns the modelling of diffractive gratings for thin silicon wafer solar cells. For this purpose, we use the rigorous coupled wave analysis to simulate Sentaurus technical computer-aided design (TCAD) is combined with the rigorous coupled wave analysis, a method to solve Maxwell's equations for periodic structures. Here we show that a grating can be used to improve the absorption in a thin silicon wafer solar cell considerably.

Peters, Marius; Fajun, Ma; Siyu, Guo; Hoex, Bram; Blaesi, Benedikt; Glunz, Stefan; Aberle, Armin; Luther, Joachim

2012-10-01

291

Advancing Cyberinfrastructure to support high resolution water resources modeling  

NASA Astrophysics Data System (ADS)

Addressing the problem of how the availability and quality of water resources at large scales are sensitive to climate variability, watershed alterations and management activities requires computational resources that combine data from multiple sources and support integrated modeling. Related cyberinfrastructure challenges include: 1) how can we best structure data and computer models to address this scientific problem through the use of high-performance and data-intensive computing, and 2) how can we do this in a way that discipline scientists without extensive computational and algorithmic knowledge and experience can take advantage of advances in cyberinfrastructure? This presentation will describe a new system called CI-WATER that is being developed to address these challenges and advance high resolution water resources modeling in the Western U.S. We are building on existing tools that enable collaboration to develop model and data interfaces that link integrated system models running within an HPC environment to multiple data sources. Our goal is to enhance the use of computational simulation and data-intensive modeling to better understand water resources. Addressing water resource problems in the Western U.S. requires simulation of natural and engineered systems, as well as representation of legal (water rights) and institutional constraints alongside the representation of physical processes. We are establishing data services to represent the engineered infrastructure and legal and institutional systems in a way that they can be used with high resolution multi-physics watershed modeling at high spatial resolution. These services will enable incorporation of location-specific information on water management infrastructure and systems into the assessment of regional water availability in the face of growing demands, uncertain future meteorological forcings, and existing prior-appropriations water rights. This presentation will discuss the informatics challenges involved with data management and easy-to-use access to high performance computing being tackled in this project.

Tarboton, D. G.; Ogden, F. L.; Jones, N.; Horsburgh, J. S.

2012-12-01

292

A Simulation Model of Technological Adoption with an Intelligent Agent  

NASA Astrophysics Data System (ADS)

Operational optimization models of technology adoptions commonly assume the existence of a social planner who knows a long-term future. Such kind of planner does not exist in reality. This paper introduces a simulation model in which an intelligent agent forms its expectation on future by continuous learning from its previous experience, and adjusts its decision on technology development continuously. Simulations with the model show that with the intelligent agent, an advanced but currently expensive technology will be adopted, but with a much slower pace than in optimization models.

Ma, Tieju; Chi, Chunjie; Chen, Jun; Shi, Yong

293

Deterministically based radar glint model for real-time simulations  

NASA Astrophysics Data System (ADS)

A new radar glint model has been created to evaluate the terminal characteristics of the Advanced Medium Range Air-to-Air Missile (AMRAAM). This model was designed to use deterministically based glint parameters that develop accurate glint characteristics for real-time simulations. The model uses a deterministically derived data table to specify the first order glint statistics; it then generates random glint characteristics which are a function of target type, target orientation, and the target rotation rate. This combination allows the model to develop radar cross section and glint data to drive the real-time AMRAAM simulation program.

Sluman, Richard V.

1993-09-01

294

OXYGEN UTILIZATION IN ACTIVATED SLUDGE PLANTS: SIMULATION AND MODEL CALIBRATION  

EPA Science Inventory

The objective of the research described in the report is to apply recent advances in activated sludge process modeling to the simulation of oxygen utilization rates in full scale activated sludge treatment plants. This is accomplished by calibrating the International Association ...

295

An advanced simulation scheme for electric railway power systems based on artificial life approach  

Microsoft Academic Search

This paper describes an advanced simulation scheme for DC electric railway power systems, taking train dynamic behaviors into consideration. The results obtained from the power system simulation are referred to aid the DC substation equipment selection process. In the present simulation, train dynamic behaviors are ignored. Therefore, simulation results are essentially different from the field data since a fleet behaves

T. Jinzenji; M. Sasaki

1998-01-01

296

Physics and modeling of dopant diffusion for advanced device applications  

NASA Astrophysics Data System (ADS)

Physically based diffusion models have been developed to simulate dopant diffusion for advanced semiconductor device technology. Based on extensive experimental results and fundamental defect related kinetics, the diffusion models has been developed to include various diffusion species and defect reactions in order to simulate the complex dopant redistribution due to transient enhanced diffusion (TED). For next generation channel doping technology, the experiment and modeling of indium diffusion during high temperature rapid thermal annealing (RTA) was carried out. The diffusion of implanted indium is a combined effect of TED and thermal equilibrium diffusion. The implanted indium cannot be fully activated after RTA due to carrier freeze-out. A diffusion model was developed to describe the indium redistribution during RTA. The TED induced by ion implantation was extensively investigated for the phosphorus diffusion during low temperature furnace annealing. The TED of implanted phosphorus shows an initial decay at the early stage of annealing, and increases with increasing implant energy and dose. Dose loss of phosphorus was found during the TED period due to interface segregation. TED was shown to dominate the dose loss process. The Hybrid diffusion model including defect clustering and interface segregation effects was developed. The model accurately simulates the TED and dose loss of implanted phosphorus during low temperature annealing. The co-diffusion study for arsenic and boron was performed to understand the boron redistribution in the channel region due to the TED caused by the arsenic source/drain implant. The boron segregation in the arsenic profile is induced by the combined effects of junction electric field and TED during annealing. The segregation is driven by the TED caused by either ion implantation or arsenic deactivation. To simulate the co-diffusion phenomenon, dislocation and arsenic clustering kinetics and their interactions with point defects are included. Results show that arsenic deactivation causes additional boron segregation which affects channel doping profile greatly and degrades the device performance.

Chang, Ruey-Dar

297

SEMI Modeling and Simulation Roadmap  

SciTech Connect

With the exponential growth in the power of computing hardware and software, modeling and simulation is becoming a key enabler for the rapid design of reliable Microsystems. One vision of the future microsystem design process would include the following primary software capabilities: (1) The development of 3D part design, through standard CAD packages, with automatic design rule checks that guarantee the manufacturability and performance of the microsystem. (2) Automatic mesh generation, for 3D parts as manufactured, that permits computational simulation of the process steps, and the performance and reliability analysis for the final microsystem. (3) Computer generated 2D layouts for process steps that utilize detailed process models to generate the layout and process parameter recipe required to achieve the desired 3D part. (4) Science-based computational tools that can simulate the process physics, and the coupled thermal, fluid, structural, solid mechanics, electromagnetic and material response governing the performance and reliability of the microsystem. (5) Visualization software that permits the rapid visualization of 3D parts including cross-sectional maps, performance and reliability analysis results, and process simulation results. In addition to these desired software capabilities, a desired computing infrastructure would include massively parallel computers that enable rapid high-fidelity analysis, coupled with networked compute servers that permit computing at a distance. We now discuss the individual computational components that are required to achieve this vision. There are three primary areas of focus: design capabilities, science-based capabilities and computing infrastructure. Within each of these areas, there are several key capability requirements.

Hermina, W.L.

2000-10-02

298

Towards a Framework for Assessing Deformable Models in Medical Simulation  

Microsoft Academic Search

Computational techniques for the analysis of mechanical problems have recently moved from traditional engineering disciplines\\u000a to biomedical simulations. Thus, the number of complex models describing the mechanical behavior of medical environments have\\u000a increased these last years. While the development of advanced computational tools has led to interesting modeling algorithms,\\u000a the relevances of these models are often criticized due to incomplete

Maud Marchal; Jérémie Allard; Christian Duriez; Stephane Cotin

2008-01-01

299

Extended robust semiconductor laser modeling for analog optical link simulations  

Microsoft Academic Search

An enhanced semiconductor laser model incorporating gain nonlinearities, gain saturation, index nonlinearities, leakage current, thermal effects, and noise effects is presented. Symbolically defined devices based on the proposed models are implemented in the Hewlett-Packard Advanced Design System computer-aided design tool. The laser model enables the simulation of the transient and steady-state dynamic characteristics of laser diodes such as carrier, photon

Samy Ghoniemy; Leonard MacEachern; Samy Mahmoud

2003-01-01

300

Deterministically based radar glint model for real-time simulations  

Microsoft Academic Search

A new radar glint model has been created to evaluate the terminal characteristics of the Advanced Medium Range Air-to-Air Missile (AMRAAM). This model was designed to use deterministically based glint parameters that develop accurate glint characteristics for real-time simulations. The model uses a deterministically derived data table to specify the first order glint statistics; it then generates random glint characteristics

Richard V. Sluman

1993-01-01

301

Crashworthiness analysis using advanced material models in DYNA3D  

SciTech Connect

As part of an electric vehicle consortium, LLNL and Kaiser Aluminum are conducting experimental and numerical studies on crashworthy aluminum spaceframe designs. They have jointly explored the effect of heat treat on crush behavior and duplicated the experimental behavior with finite-element simulations. The major technical contributions to the state of the art in numerical simulation arise from the development and use of advanced material model descriptions for LLNL`s DYNA3D code. Constitutive model enhancements in both flow and failure have been employed for conventional materials such as low-carbon steels, and also for lighter weight materials such as aluminum and fiber composites being considered for future vehicles. The constitutive model enhancements are developed as extensions from LLNL`s work in anisotropic flow and multiaxial failure modeling. Analysis quality as a function of level of simplification of material behavior and mesh is explored, as well as the penalty in computation cost that must be paid for using more complex models and meshes. The lightweight material modeling technology is being used at the vehicle component level to explore the safety implications of small neighborhood electric vehicles manufactured almost exclusively from these materials.

Logan, R.W.; Burger, M.J.; McMichael, L.D. [Lawrence Livermore National Lab., CA (United States); Parkinson, R.D. [Kaiser Aluminum & Chemical Corp., Pleasanton, CA (United States). Center for Technology

1993-10-22

302

Teaching advanced cardiac life support protocols: the effectiveness of static versus high-fidelity simulation.  

PubMed

The purpose of this study was to compare the effectiveness of static simulation to high-fidelity simulation when teaching advanced cardiac life support guidelines. Using a quasi-experimental design, 49 BSN students were randomly assigned to 2 groups of either static or high-fidelity simulation. There were no significant differences between the static and high-fidelity simulation groups on the written examination. The high-fidelity simulation group outperformed the static simulation group on megacode performance. PMID:21330894

King, Jason M; Reising, Deanna L

2011-01-01

303

Space-based radar representation in the advanced warfighting simulation (AWARS)  

NASA Astrophysics Data System (ADS)

Space and orbiting systems impact multiple battlefield operating systems (BOS). Space support to current operations is a perfect example of how the United States fights. Satellite-aided munitions, communications, navigation and weather systems combine to achieve military objectives in a relatively short amount of time. Through representation of space capabilities within models and simulations, the military will have the ability to train and educate officers and soldiers to fight from the high ground of space or to conduct analysis and determine the requirements or utility of transformed forces empowered with advanced space-based capabilities. The Army Vice Chief of Staff acknowledged deficiencies in space modeling and simulation during the September 2001 Space Force Management Analsyis Review (FORMAL) and directed that a multi-disciplinary team be established to recommend a service-wide roadmap to address shortcomings. A Focus Area Collaborative Team (FACT), led by the U.S. Army Space & Missile Defense Command with participation across the Army, confirmed the weaknesses in scope, consistency, correctness, completeness, availability, and usability of space model and simulation (M&S) for Army applications. The FACT addressed the need to develop a roadmap to remedy Space M&S deficiencies using a highly parallelized process and schedule designed to support a recommendation during the Sep 02 meeting of the Army Model and Simulation Executive Council (AMSEC).

Phend, Andrew E.; Buckley, Kathryn; Elliott, Steven R.; Stanley, Page B.; Shea, Peter M.; Rutland, Jimmie A.

2004-09-01

304

Advancing an Information Model for Environmental Observations  

NASA Astrophysics Data System (ADS)

Observational data are fundamental to hydrology and water resources, and the way they are organized, described, and shared either enables or inhibits the analyses that can be performed using the data. The CUAHSI Hydrologic Information System (HIS) project is developing cyberinfrastructure to support hydrologic science by enabling better access to hydrologic data. HIS is composed of three major components. HydroServer is a software stack for publishing time series of hydrologic observations on the Internet as well as geospatial data using standards-based web feature, map, and coverage services. HydroCatalog is a centralized facility that catalogs the data contents of individual HydroServers and enables search across them. HydroDesktop is a client application that interacts with both HydroServer and HydroCatalog to discover, download, visualize, and analyze hydrologic observations published on one or more HydroServers. All three components of HIS are founded upon an information model for hydrologic observations at stationary points that specifies the entities, relationships, constraints, rules, and semantics of the observational data and that supports its data services. Within this information model, observations are described with ancillary information (metadata) about the observations to allow them to be unambiguously interpreted and used, and to provide traceable heritage from raw measurements to useable information. Physical implementations of this information model include the Observations Data Model (ODM) for storing hydrologic observations, Water Markup Language (WaterML) for encoding observations for transmittal over the Internet, the HydroCatalog metadata catalog database, and the HydroDesktop data cache database. The CUAHSI HIS and this information model have now been in use for several years, and have been deployed across many different academic institutions as well as across several national agency data repositories. Additionally, components of the HIS have been modified to support data management for the Critical Zone Observatories (CZOs). This paper will present limitations of the existing information model used by the CUAHSI HIS that have been uncovered through its deployment and use, as well as new advances to the information model, including: better representation of both in situ observations from field sensors and observations derived from environmental samples, extensibility in attributes used to describe observations, and observation provenance. These advances have been developed by the HIS team and the broader scientific community and will enable the information model to accommodate and better describe wider classes of environmental observations and to better meet the needs of the hydrologic science and CZO communities.

Horsburgh, J. S.; Aufdenkampe, A. K.; Hooper, R. P.; Lehnert, K. A.; Schreuders, K.; Tarboton, D. G.; Valentine, D. W.; Zaslavsky, I.

2011-12-01

305

Bjt Modeling for Circuit Simulation  

NASA Astrophysics Data System (ADS)

Physical models for transport mechanisms important in bipolar transistors are developed, implemented in SPICE3 for DC, AC, and transient analyses, and assessed with numerical device simulations. The analytical model of quasi-saturation, or base -push-out, is derived for all current levels. Deficiencies in previous quasi-saturation models are revealed and overcome. The quasi-saturation model is based on a derivation of the current-induced-base charge and the electric field in the collector for all bias conditions. Physical models for base-width modulation (BWM) at the collector-base (cb) junction and impact ionization in the collector are formulated as functions of the electric field; inclusion of these two effects greatly improves the accuracy in the output resistance. The impact ionization model gives a first -order description of avalanche breakdown, or snapback. The dynamic charge storage effects are investigated in detail with AC and transient analyses. The proper partitioning of the dynamic charging currents is made possible by the addition of an internal collector node and increases accuracy especially under quasi-saturation conditions. The cb junction capacitance and the cb junction transit time tau _{cv} are expressed as functions of the field E_1 at the cb junction. As E_1 decreases with increasing current due to the Kirk effect, the variable tau _{cv} and the BWM effect on the base-diffusion charge each can cause f_ {T} to fall-off at a current several times below that for the onset of quasi-saturation, which causes a more rapid f_{T} fall -off. The current-induced-base charge significantly reduces the effective base resistance as the dynamic base current flows laterally through the current-induced-base. Simulation results suggest that an AC emitter crowding model previously derived for low injection conditions is a good approximation even under base-push-out conditions. The delay time approach and the quasi-static charge-partition approach are compared; the former is found to be better in simulating the high frequency effects due to non-quasi-static conditions in the quasi-neutral base and current-induced-base regions. A non-quasi-static model for the charge in the quasi-neutral base region is developed and implemented in SPICE3 for transient analysis. The methodology to solve for the instantaneous carrier distribution by a series solution including all injection levels and the effect of the built-in field is presented. The solution applies for forward and reverse modes of operation. Analytic equations for the instantaneous base charge partitions are derived for the calculation of the instantaneous node currents. For switching times comparable to the base transit time, the non-quasi-static model is significantly more accurate than the Gummel-Poon model and previous quasi-static charge -partition models, as verified with numerical device simulations.

Szeto, Clement Keung

306

Simulation and Modeling of Homogeneous, Compressed Turbulence.  

NASA Astrophysics Data System (ADS)

Low Reynolds number homogeneous turbulence undergoing low Mach number isotropic and one-dimensional compression has been simulated by numerically solving the Navier-Stokes equations. The numerical simulations were carried out on a CYBER 205 computer using a 64 x 64 x 64 mesh. A spectral method was used for spatial differencing and the second -order Runge-Kutta method for time advancement. A variety of statistical information was extracted from the computed flow fields. These include three-dimensional energy and dissipation spectra, two-point velocity correlations, one -dimensional energy spectra, turbulent kinetic energy and its dissipation rate, integral length scales, Taylor microscales, and Kolmogorov length scale. It was found that the ratio of the turbulence time scale to the mean-flow time scale is an important parameter in these flows. When this ratio is large, the flow is immediately affected by the mean strain in a manner similar to that predicted by rapid distortion theory. When this ratio is small, the flow retains the character of decaying isotropic turbulence initially; only after the strain has been applied for a long period does the flow accumulate a significant reflection of the effect of mean strain. In these flows, the Kolmogorov length scale decreases rapidly with increasing total strain, due to the density increase that accompanies compression. Results from the simulated flow fields were used to test one-point-closure, two-equation turbulence models. The two-equation models perform well only when the compression rate is small compared to the eddy turn-over rate. A new one-point-closure, three-equation turbulence model which accounts for the effect of compression is proposed. The new model accurately calculates four types of flows (isotropic decay, isotropic compression, one-dimensional compression, and axisymmetric expansion flows) for a wide range of strain rates.

Wu, Chung-Teh

307

Advanced thermal energy management: A thermal test bed and heat pipe simulation  

NASA Astrophysics Data System (ADS)

Work initiated on a common-module thermal test simulation was continued, and a second project on heat pipe simulation was begun. The test bed, constructed from surplus Skylab equipment, was modeled and solved for various thermal load and flow conditions. Low thermal load caused the radiator fluid, Coolanol 25, to thicken due to its temperature avoided by using a regenerator-heat-exchanger. Other possible solutions modeled include a radiator heater and shunting heat from the central thermal bus to the radiator. Also, module air temperature can become excessive with high avionics load. A second preoject concerning advanced heat pipe concepts was initiated. A program was written which calculates fluid physical properties, liquid and vapor pressure in the evaporator and condenser, fluid flow rates, and thermal flux. The program is directed to evaluating newer heat pipe wicks and geometries, especially water in an artery surrounded by six vapor channels. Effects of temperature, groove and slot dimensions, and wick properties are reported.

Barile, Ronald G.

1986-11-01

308

Advanced thermal energy management: A thermal test bed and heat pipe simulation  

NASA Technical Reports Server (NTRS)

Work initiated on a common-module thermal test simulation was continued, and a second project on heat pipe simulation was begun. The test bed, constructed from surplus Skylab equipment, was modeled and solved for various thermal load and flow conditions. Low thermal load caused the radiator fluid, Coolanol 25, to thicken due to its temperature avoided by using a regenerator-heat-exchanger. Other possible solutions modeled include a radiator heater and shunting heat from the central thermal bus to the radiator. Also, module air temperature can become excessive with high avionics load. A second preoject concerning advanced heat pipe concepts was initiated. A program was written which calculates fluid physical properties, liquid and vapor pressure in the evaporator and condenser, fluid flow rates, and thermal flux. The program is directed to evaluating newer heat pipe wicks and geometries, especially water in an artery surrounded by six vapor channels. Effects of temperature, groove and slot dimensions, and wick properties are reported.

Barile, Ronald G.

1986-01-01

309

Automatic programming of AGVS simulation models  

Microsoft Academic Search

This paper presents a knowledge based modeling system that allows a manufacturing engineer who has very limited knowledge of simulation methodology to quickly and correctly, develop and run a simulation model of an automated guided vehicle system (AGVS). The modeling system is capable of guiding and assisting the engineer with a level of “expertise” comparable to a trained simulation specialist.

Mark K. Brazier; Robert E. Shannon

1987-01-01

310

Advanced virtual energy simulation training and research: IGCC with CO2 capture power plant  

Microsoft Academic Search

In this presentation, we highlight the deployment of a real-time dynamic simulator of an integrated gasification combined cycle (IGCC) power plant with CO capture at the Department of Energy's (DOE) National Energy Technology Laboratory's (NETL) Advanced Virtual Energy Simulation Training and Research (AVESTARTM) Center. The Center was established as part of the DOE's accelerating initiative to advance new clean coal

S. Zitney; E. Liese; P. Mahapatra; D. Bhattacharyya; G. Provost

2011-01-01

311

Operations planning simulation: Model study  

NASA Technical Reports Server (NTRS)

The use of simulation modeling for the identification of system sensitivities to internal and external forces and variables is discussed. The technique provides a means of exploring alternate system procedures and processes, so that these alternatives may be considered on a mutually comparative basis permitting the selection of a mode or modes of operation which have potential advantages to the system user and the operator. These advantages are measurements is system efficiency are: (1) the ability to meet specific schedules for operations, mission or mission readiness requirements or performance standards and (2) to accomplish the objectives within cost effective limits.

1974-01-01

312

Model Validation with Hybrid Dynamic Simulation  

SciTech Connect

Abstract—Model validation has been one of the central topics in power engineering studies for years. As model validation aims at obtaining reasonable models to represent actual behavior of power system components, it has been essential to validate models against actual measurements or known benchmark behavior. System-wide model simulation results can be compared with actual recordings. However, it is difficult to construct a simulation case for a large power system such as the WECC system and to narrow down to problematic models in a large system. Hybrid dynamic simulation with its capability of injecting external signals into dynamic simulation enables rigorous comparison of measurements and simulation in a small subsystem of interest. This paper presents such a model validation methodology with hybrid dynamic simulation. Two application examples on generator and load model validation are presented to show the validity of this model validation methodology. This methodology is further extended for automatic model validation and dichotomous subsystem model validation.

Huang, Zhenyu; Kosterev, Dmitry; Guttromson, Ross T.; Nguyen, Tony B.

2006-06-18

313

Advanced wellbore thermal simulator GEOTEMP2 user manual  

SciTech Connect

GEOTEMP2 is a wellbore thermal simulator computer code designed for geothermal drilling and production applications. The code treats natural and forced convection and conduction within the wellbore and heat conduction within the surrounding rock matrix. A variety of well operations can be modeled including injection, production, forward, and reverse circulation with gas or liquid, gas or liquid drilling, and two-phase steam injection and production. Well completion with several different casing sizes and cement intervals can be modeled. The code allows variables suchas flow rate to change with time enabling a realistic treatment of well operations. This user manual describes the input required to properly operate the code. Ten sample problems are included which illustrate all the code options. Complete listings of the code and the output of each sample problem are provided.

Mondy, L.A.; Duda, L.E.

1984-11-01

314

[Research advance on lake ecosystem dynamic models].  

PubMed

Starting with the role of system analysis in lake ecosystem research, this paper summarized the tentative procedures and softwares for studying the dynamics of lake ecosystem. There are several main stages in modeling the dynamics of lake ecosystem, namely, problems identification, mathematical formulation, computation, validation, sensitive analysis, calibration, and verification. In the modeling, selecting temporal and spatial scales is essential but complex. Since 1960s, a rapid progress has been made in modeling the dynamics of lake ecosystem, being developed from simple zero-dimension models to complex ecological-aquatic-hydrodynamic ones, among which, exergy was applied popularly as an objective function in modeling. In this paper, LakeWeb and LEEDS (Lake Eutrophication, Effect, Dose, and Sensitivity model) were analyzed as examples. In China, the development of lake ecosystem dynamic models could be traced back to 1980s, and most of them were focused on Lake Dianch, Lake Taihu, Lake Chaohu and Lake Donghu. Some softwares such as CE-QUAL-ICM, WASP, AQUATOX, PAMOLARE and CAEDYM were developed to simulate lake ecosystem dynamics, among which, CE-QUAL-ICM is more suitable for long and narrow water bodies. WASP consists of three parts, i. e., DYNHYD, EUTRO, and TOXI. AQUATOX is an ecological risk model, and the parameters are mainly calibrated in U. S. A, which has limited its further application in China. The software ECOPATH for simulating the energy flows in lakes was also described in this paper. There are still many shortages in the lake ecosystem dynamic models, e. g., the lack of sufficient monitoring data for validation, insufficient consideration of uncertainties and the role of bacteria, and inconsistent relationship with watershed changes. The uncertainties are mainly from the intrinsic uncertainties in aquatic ecosystem, in modeling, in parameters selection, and also in forecast and application. Setting up long-term monitoring and data sharing mechanism, using interpolation to make data more densely, introducing objective functions, dealing with uncertainties, and constructing watershed-lake ecosystem dynamic model could be the available ways for overcoming the shortages. PMID:16180776

Liu, Yong; Guo, Huaicheng; Fan, Yingying; Wang, Lijing

2005-06-01

315

Recent Advances in the Freely Available Discrete Fracture Reservoir Simulator, NFFLOW  

NASA Astrophysics Data System (ADS)

Many of the reservoirs in the world today that are most important for unconventional resource development are fractured. These include, but are not limited to, geothermal resources, shale oil development, and natural gas production in tight sands and shales. A robust discrete fracture reservoir simulator, NFFLOW, has been developed for single-phase single-component flow in fractured tight rock formations. This simulator, paired with the fracture network generation code FRACGEN, is capable of evaluating the flow through highly complex fractured formations. The simulator models fluid flow in idealized fractures, with injection and production wells. Rock matrix flow is modeled using Darcy’s law, and dynamic recharge of flow into the fractures is accounted for. Fracture networks are stochastically generated using FRACGEN, which also allows the manual inclusion of known fractures. For this presentation, the advances which are currently being developed for this freely available simulator are discussed, including multi-layer simulations, multi-component flow, and enhanced visualization of networks and results.

King, S.; Sams, N.; Gyovai, K.; Bromhal, G. S.; Crandall, D.

2010-12-01

316

Mission simulation as an approach to develop requirements for automation in Advanced Life Support Systems.  

PubMed

This paper examines mission simulation as an approach to develop requirements for automation and robotics for Advanced Life Support Systems (ALSS). The focus is on requirements and applications for command and control, control and monitoring, situation assessment and response, diagnosis and recovery, adaptive planning and scheduling, and other automation applications in addition to mechanized equipment and robotics applications to reduce the excessive human labor requirements to operate and maintain an ALSS. Based on principles of systems engineering, an approach is proposed to assess requirements for automation and robotics using mission simulation tools. First, the story of a simulated mission is defined in terms of processes with attendant types of resources needed, including options for use of automation and robotic systems. Next, systems dynamics models are used in simulation to reveal the implications for selected resource allocation schemes in terms of resources required to complete operational tasks. The simulations not only help establish ALSS design criteria, but also may offer guidance to ALSS research efforts by identifying gaps in knowledge about procedures and/or biophysical processes. Simulations of a planned one-year mission with 4 crewmembers in a Human Rated Test Facility are presented as an approach to evaluation of mission feasibility and definition of automation and robotics requirements. PMID:11538963

Erickson, J D; Eckelkamp, R E; Barta, D J; Dragg, J

1996-01-01

317

Recent Advances in First-Principle Simulation of the Transition from Continuous to Discontinuous Failure under Impact  

Microsoft Academic Search

Summary By discretizing wave, diffusion and instantaneous response equations in a single computational domain, a computer test-bed is being developed for the first-principle simulation of multi-scale structural failure under blast and impact loads. Based on the previous work (Chen, 2000; Chen et al., 2001; 2002 and 2003), recent advances in model- based simulation of the transition from continuous to discontinuous

Zhiyuan Chen

2009-01-01

318

A Social Diffusion Model with an Application on Election Simulation  

PubMed Central

Issues about opinion diffusion have been studied for decades. It has so far no empirical approach to model the interflow and formation of crowd's opinion in elections due to two reasons. First, unlike the spread of information or flu, individuals have their intrinsic attitudes to election candidates in advance. Second, opinions are generally simply assumed as single values in most diffusion models. However, in this case, an opinion should represent preference toward multiple candidates. Previously done models thus may not intuitively interpret such scenario. This work is to design a diffusion model which is capable of managing the aforementioned scenario. To demonstrate the usefulness of our model, we simulate the diffusion on the network built based on a publicly available bibliography dataset. We compare the proposed model with other well-known models such as independent cascade. It turns out that our model consistently outperforms other models. We additionally investigate electoral issues with our model simulator.

Wang, Fu-Min; Hung, San-Chuan; Kung, Perng-Hwa; Lin, Shou-De

2014-01-01

319

A social diffusion model with an application on election simulation.  

PubMed

Issues about opinion diffusion have been studied for decades. It has so far no empirical approach to model the interflow and formation of crowd's opinion in elections due to two reasons. First, unlike the spread of information or flu, individuals have their intrinsic attitudes to election candidates in advance. Second, opinions are generally simply assumed as single values in most diffusion models. However, in this case, an opinion should represent preference toward multiple candidates. Previously done models thus may not intuitively interpret such scenario. This work is to design a diffusion model which is capable of managing the aforementioned scenario. To demonstrate the usefulness of our model, we simulate the diffusion on the network built based on a publicly available bibliography dataset. We compare the proposed model with other well-known models such as independent cascade. It turns out that our model consistently outperforms other models. We additionally investigate electoral issues with our model simulator. PMID:24995351

Lou, Jing-Kai; Wang, Fu-Min; Tsai, Chin-Hua; Hung, San-Chuan; Kung, Perng-Hwa; Lin, Shou-De; Chen, Kuan-Ta; Lei, Chin-Laung

2014-01-01

320

Detailed simulation of morphodynamics: 1. Hydrodynamic model  

NASA Astrophysics Data System (ADS)

We present a three-dimensional high-resolution hydrodynamic model for unsteady incompressible flow over an evolving bed topography. This is achieved by using a multilevel Cartesian grid technique that allows the grid to be refined in high-gradient regions and in the vicinity of the river bed. The grid can be locally refined and adapted to the bed geometry, managing the Cartesian grid cells and faces using a hierarchical tree data approach. A ghost-cell immersed-boundary technique is applied to cells intersecting the bed topography. The governing equations have been discretized using a finite-volume method on a staggered grid, conserving second-order accuracy in time and space. The solution advances in time using the fractional step approach. Large-eddy simulation is used as turbulence closure. We validate the model against several experiments and other results from literature. Model results for Stokes flow around a cylinder in the vicinity of a moving wall agree well with Wannier's analytical solution. At higher Reynolds numbers, computed trailing bubble length, separation angle, and drag coefficient compare favorably with experimental and previous computational results. Results for the flow over two- and three-dimensional dunes agree well with published data, including a fair reproduction of recirculation zones, horse-shoe structures, and boiling effects. This shows that the model is suitable for being used as a hydrodynamic submodel in the high-resolution modeling of sediment transport and formation and evolution of subaqueous ripples and dunes.

Nabi, M.; de Vriend, H. J.; Mosselman, E.; Sloff, C. J.; Shimizu, Y.

2012-12-01

321

Verification, Validation and Credibility Assessment of a Computational Model of the Advanced Resistive Exercise Device (ARED)  

NASA Technical Reports Server (NTRS)

The Advanced Resistive Exercise Device (ARED) is the resistive exercise device used by astronauts on the International Space Station (ISS) to mitigate bone loss and muscle atrophy due to extended exposure to microgravity (micro g). The Digital Astronaut Project (DAP) has developed a multi-body dynamics model of biomechanics models for use in spaceflight exercise physiology research and operations. In an effort to advance model maturity and credibility of the ARED model, the DAP performed verification, validation and credibility (VV and C) assessment of the analyses of the model in accordance to NASA-STD-7009 'Standards for Models and Simulations'.

Werner, C. R.; Humphreys, B. T.; Mulugeta, L.

2014-01-01

322

Ubiquitin: molecular modeling and simulations.  

PubMed

The synthesis and destruction of proteins are imperative for maintaining their cellular homeostasis. In the 1970s, Aaron Ciechanover, Avram Hershko, and Irwin Rose discovered that certain proteins are tagged by ubiquitin before degradation, a discovery that awarded them the 2004 Nobel Prize in Chemistry. Compelling data gathered during the last several decades show that ubiquitin plays a vital role not only in protein degradation but also in many cellular functions including DNA repair processes, cell cycle regulation, cell growth, immune system functionality, hormone-mediated signaling in plants, vesicular trafficking pathways, regulation of histone modification and viral budding. Due to the involvement of ubiquitin in such a large number of diverse cellular processes, flaws and impairments in the ubiquitin system were found to be linked to cancer, neurodegenerative diseases, genetic disorders, and immunological disorders. Hence, deciphering the dynamics and complexity of the ubiquitin system is of significant importance. In addition to experimental techniques, computational methodologies have been gaining increasing influence in protein research and are used to uncover the structure, stability, folding, mechanism of action and interactions of proteins. Notably, molecular modeling and molecular dynamics simulations have become powerful tools that bridge the gap between structure and function while providing dynamic insights and illustrating essential mechanistic characteristics. In this study, we present an overview of molecular modeling and simulations of ubiquitin and the ubiquitin system, evaluate the status of the field, and offer our perspective on future progress in this area of research. PMID:24113788

Ganoth, Assaf; Tsfadia, Yossi; Wiener, Reuven

2013-11-01

323

Recent advances in 3D computed tomography techniques for simulation and navigation in hepatobiliary pancreatic surgery.  

PubMed

A few years ago it could take several hours to complete a 3D image using a 3D workstation. Thanks to advances in computer science, obtaining results of interest now requires only a few minutes. Many recent 3D workstations or multimedia computers are equipped with onboard 3D virtual patient modeling software, which enables patient-specific preoperative assessment and virtual planning, navigation, and tool positioning. Although medical 3D imaging can now be conducted using various modalities, including computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and ultrasonography (US) among others, the highest quality images are obtained using CT data, and CT images are now the most commonly used source of data for 3D simulation and navigation image. If the 2D source image is bad, no amount of 3D image manipulation in software will provide a quality 3D image. In this exhibition, the recent advances in CT imaging technique and 3D visualization of the hepatobiliary and pancreatic abnormalities are featured, including scan and image reconstruction technique, contrast-enhanced techniques, new application of advanced CT scan techniques, and new virtual reality simulation and navigation imaging. PMID:24464989

Uchida, Masafumi

2014-04-01

324

Advanced Plasticity Models Applied to Recent Shock Data on Beryllium  

NASA Astrophysics Data System (ADS)

Recent plate impact experiments with pressures from 2 to 20 GPa have been performed on vacuum hot-pressed S-200F Beryllium. This hexagonal close-packed (HCP) metal shows significant plasticity effects. To examine the validity of advanced plasticity models in the shock regime, the plate impact experiments were modeled using a Lagrangian hydrocode. Two constitutive strength (plasticity) models, the Preston-Tonks-Wallace (PTW) and Mechanical Threshold Stress (MTS) models, were calibrated using the same extensive set of quasi-static and Hopkinson bar data taken at temperatures from 77K to 873K and strain rates from 0.001/sec to 4300/sec. In spite of being calibrated on the same data, the two models give noticeably different results when comparing with the experimentally measured wave profiles. Neither model is unequivocally superior, with each matching some aspects of the data better. The reasons for the differences are explored and discussed. Differences between the two models are particularly evident during reverse loading upon shock release, which is also examined. The performance of simpler plasticity models than PTW or MTS in simulating the impact tests is also presented for reference.

Prime, Michael; Adams, Chris; Chen, Shuh-Rong

2011-06-01

325

Modeling of Army Research Laboratory EMP simulators  

SciTech Connect

Models are required that permit the estimation of emitted field signatures from EMP simulators to design the simulator antenna structure, to establish the usable test volumes, and to estimate human exposure risk. This paper presents the capabilities and limitations of a variety of EMP simulator models useful to the Army's EMP survivability programs. Comparisons among frequency and time-domain models are provided for two powerful US Army Research Laboratory EMP simulators: AESOP (Army EMP Simulator Operations) and VEMPS II (Vertical EMP Simulator II).

Miletta, J.R.; Chase, R.J.; Luu, B.B. (Army Research Lab., Adelphi, MD (United States)); Williams, J.W.; Viverito, V.J. (Science Applications International Corp., Germantown, MD (United States))

1993-12-01

326

Advanced aviation concepts via simulation: techniques to enhance performance of an existing aviation simulation  

Microsoft Academic Search

Facing a need to run large scenarios on aviation models more quickly than the one to two days currently required, the MITRE Corporation undertook an effort to reduce the execution time of one such simulation. Time and cost constraints prohibited a major rewrite of the almost one million existing lines of code, so only solutions requiring minimal changes to the

David Carnes; Frederick Wieland

2002-01-01

327

Advanced modeling of active control of fan noise for ultra high bypass turbofan engines  

Microsoft Academic Search

An advanced model of active control of fan noise for ultra high bypass turbofan engines has been developed. This model is based on a boundary integral equation method and simulates the propagation, radiation and control of the noise generated by an engine fan surrounded by a duct of finite length and cylindrical shape, placed in a uniform flow. Control sources,

Florence Vanel Hutcheson

1999-01-01

328

USER'S GUIDE FOR THE ADVANCED STATISTICAL TRAJECTORY REGIONAL AIR POLLUTION (ASTRAP) MODEL  

EPA Science Inventory

The Advanced Statistical Trajectory Regional Air Pollution (ASTRAP) model simulates long-range, long-term transport and deposition of air pollutants, primarily oxides of sulfur and nitrogen. The ASTRAP model is designed to combine ease of exercise with an appropriate detail of ph...

329

Efficient Multi-Dimensional Simulation of Quantum Confinement Effects in Advanced MOS Devices  

NASA Technical Reports Server (NTRS)

We investigate the density-gradient (DG) transport model for efficient multi-dimensional simulation of quantum confinement effects in advanced MOS devices. The formulation of the DG model is described as a quantum correction ot the classical drift-diffusion model. Quantum confinement effects are shown to be significant in sub-100nm MOSFETs. In thin-oxide MOS capacitors, quantum effects may reduce gate capacitance by 25% or more. As a result, the inclusion of quantum effects may reduce gate capacitance by 25% or more. As a result, the inclusion of quantum effects in simulations dramatically improves the match between C-V simulations and measurements for oxide thickness down to 2 nm. Significant quantum corrections also occur in the I-V characteristics of short-channel (30 to 100 nm) n-MOSFETs, with current drive reduced by up to 70%. This effect is shown to result from reduced inversion charge due to quantum confinement of electrons in the channel. Also, subthreshold slope is degraded by 15 to 20 mV/decade with the inclusion of quantum effects via the density-gradient model, and short channel effects (in particular, drain-induced barrier lowering) are noticeably increased.

Biegel, Bryan A.; Ancona, Mario G.; Rafferty, Conor S.; Yu, Zhiping

2000-01-01

330

Efficient Multi-Dimensional Simulation of Quantum Confinement Effects in Advanced MOS Devices  

NASA Technical Reports Server (NTRS)

We investigate the density-gradient (DG) transport model for efficient multi-dimensional simulation of quantum confinement effects in advanced MOS devices. The formulation of the DG model is described as a quantum correction to the classical drift-diffusion model. Quantum confinement effects are shown to be significant in sub-100nm MOSFETs. In thin-oxide MOS capacitors, quantum effects may reduce gate capacitance by 25% or more. As a result, the inclusion or quantum effects in simulations dramatically improves the match between C-V simulations and measurements for oxide thickness down to 2 nm. Significant quantum corrections also occur in the I-V characteristics of short-channel (30 to 100 nm) n-MOSFETs, with current drive reduced by up to 70%. This effect is shown to result from reduced inversion charge due to quantum confinement of electrons in the channel. Also, subthreshold slope is degraded by 15 to 20 mV/decade with the inclusion of quantum effects via the density-gradient model, and short channel effects (in particular, drain-induced barrier lowering) are noticeably increased.

Biegel, Bryan A.; Rafferty, Conor S.; Ancona, Mario G.; Yu, Zhi-Ping

2000-01-01

331

Verification and validation of simulation models  

Microsoft Academic Search

This paper surveys verification and validation of models, especially simulation models in operations research. For verification it discusses 1) general good programming practice (such as modular programming), 2) checking intermediate simulation outputs through tracing and statistical testing per module, 3) statistical testing of final simulation outputs against analytical results, and 4) animation. For validation it discusses 1) obtaining real-worl data,

Jack P. C. Kleijnen

1995-01-01

332

Use of Advanced Meteorological Model Output for Coastal Ocean Modeling in Puget Sound  

SciTech Connect

It is a great challenge to specify meteorological forcing in estuarine and coastal circulation modeling using observed data because of the lack of complete datasets. As a result of this limitation, water temperature is often not simulated in estuarine and coastal modeling, with the assumption that density-induced currents are generally dominated by salinity gradients. However, in many situations, temperature gradients could be sufficiently large to influence the baroclinic motion. In this paper, we present an approach to simulate water temperature using outputs from advanced meteorological models. This modeling approach was applied to simulate annual variations of water temperatures of Puget Sound, a fjordal estuary in the Pacific Northwest of USA. Meteorological parameters from North American Region Re-analysis (NARR) model outputs were evaluated with comparisons to observed data at real-time meteorological stations. Model results demonstrated that NARR outputs can be used to drive coastal ocean models for realistic simulations of long-term water-temperature distributions in Puget Sound. Model results indicated that the net flux from NARR can be further improved with the additional information from real-time observations.

Yang, Zhaoqing; Khangaonkar, Tarang; Wang, Taiping

2011-06-01

333

Modeling and simulation of power electronic converters  

Microsoft Academic Search

This paper reviews some of the major approaches to modeling and simulation in power electronics, and provides references that can serve as a starting point for the extensive literature on the subject. The major focus of the paper is on averaged models of various kinds, but sampled-data models are also introduced. The importance of hierarchical modeling and simulation is emphasized

DRAGAN MAKSIMOVIC ´; ALEKSANDAR M. STANKOVIC; V. JOSEPH THOTTUVELIL; GEORGE C. VERGHESE

2001-01-01

334

Modeling and simulation of non-smooth mechanical systems  

Microsoft Academic Search

An advanced modeling of two real physical non-smooth objects is carried out. The non-linear ordinary differential and algebraic inequalities are derived and then numerically simulated. Various aspects of non-linear dynamics are addressed, illustrated and discussed. In the first case, the triple physical pendulum with barriers is used to model a piston-connecting rod-crankshaft system of a mono-cylinder combustion engine. Among other

J. Awrejcewicz; G. Kudra; P. Olejnik

2003-01-01

335

Hybrid simulation models of computer systems  

Microsoft Academic Search

This paper describes the structure and operation of a hybrid simulation model in which both discrete-event simulation and analytic techniques are combined to produce efficient yet accurate system models. In an example based on a simple hypothetical computer system, discrete-event simulation is used to model the arrival and activation of jobs, and a central-server queueing network models the use of

Herbert D. Schwetman; D. Siewiorek

1978-01-01

336

Advanced Method to Estimate Fuel Slosh Simulation Parameters  

NASA Technical Reports Server (NTRS)

The nutation (wobble) of a spinning spacecraft in the presence of energy dissipation is a well-known problem in dynamics and is of particular concern for space missions. The nutation of a spacecraft spinning about its minor axis typically grows exponentially and the rate of growth is characterized by the Nutation Time Constant (NTC). For launch vehicles using spin-stabilized upper stages, fuel slosh in the spacecraft propellant tanks is usually the primary source of energy dissipation. For analytical prediction of the NTC this fuel slosh is commonly modeled using simple mechanical analogies such as pendulums or rigid rotors coupled to the spacecraft. Identifying model parameter values which adequately represent the sloshing dynamics is the most important step in obtaining an accurate NTC estimate. Analytic determination of the slosh model parameters has met with mixed success and is made even more difficult by the introduction of propellant management devices and elastomeric diaphragms. By subjecting full-sized fuel tanks with actual flight fuel loads to motion similar to that experienced in flight and measuring the forces experienced by the tanks these parameters can be determined experimentally. Currently, the identification of the model parameters is a laborious trial-and-error process in which the equations of motion for the mechanical analog are hand-derived, evaluated, and their results are compared with the experimental results. The proposed research is an effort to automate the process of identifying the parameters of the slosh model using a MATLAB/SimMechanics-based computer simulation of the experimental setup. Different parameter estimation and optimization approaches are evaluated and compared in order to arrive at a reliable and effective parameter identification process. To evaluate each parameter identification approach, a simple one-degree-of-freedom pendulum experiment is constructed and motion is induced using an electric motor. By applying the estimation approach to a simple, accurately modeled system, its effectiveness and accuracy can be evaluated. The same experimental setup can then be used with fluid-filled tanks to further evaluate the effectiveness of the process. Ultimately, the proven process can be applied to the full-sized spinning experimental setup to quickly and accurately determine the slosh model parameters for a particular spacecraft mission. Automating the parameter identification process will save time, allow more changes to be made to proposed designs, and lower the cost in the initial design stages.

Schlee, Keith; Gangadharan, Sathya; Ristow, James; Sudermann, James; Walker, Charles; Hubert, Carl

2005-01-01

337

Advanced Simulation in Undergraduate Pilot Training: Systems Integration. Final Report (February 1972-March 1975).  

ERIC Educational Resources Information Center

The Advanced Simulator for Undergraduate Pilot Training (ASUPT) was designed to investigate the role of simulation in the future Undergraduate Pilot Training (UPT) program. The problem addressed in this report was one of integrating two unlike components into one synchronized system. These two components were the Basic T-37 Simulators and their…

Larson, D. F.; Terry, C.

338

Modeling, Simulation and Visualization of Aerocapture  

NASA Astrophysics Data System (ADS)

A vehicle travelling from Earth to another planet on a ballistic trajectory approaches that planet at hyperbolic velocity. Upon arrival, the vehicle must significantly reduce its speed for orbit insertion. Traditionally, this deceleration has been achieved by propulsive capture, which consumes a large amount of propellant. Aerocapture offers a more fuel-efficient alternative by exploiting vehicular drag in the planet's atmosphere. However, this technique generates extreme heat, necessitating a special thermal protection shield (TPS). Performing a trade study between the propellant mass required for propulsive capture and the TPS mass required for aerocapture can help determine which method is more desirable for a particular mission. The research objective of this thesis was to analyze aerocapture dynamics for the advancement of this trade study process. The result was an aerocapture simulation tool (ACAPS) developed in MATLAB with SIMULINK, emphasizing code validation, upgradeability, user-friendliness and trajectory visualization. The current version, ACAPS 1.1, is a three- degrees-of-freedom point mass simulation model that incorporates a look-up table for the Mars atmosphere. ACAPS is expected to supplement the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL) Project Design Center (PDC) toolkit as preliminary design software for the Mars 2005 Sample Return (MSR) Mission, Mars 2007 Mission, Mars Micromissions, Neptune/Triton Mission, and Human Mars Mission.

leszcynski, Zigmond V.

1998-12-01

339

Advanced virtual energy simulation training and research: IGCC with CO2 capture power plant  

SciTech Connect

In this presentation, we highlight the deployment of a real-time dynamic simulator of an integrated gasification combined cycle (IGCC) power plant with CO{sub 2} capture at the Department of Energy's (DOE) National Energy Technology Laboratory's (NETL) Advanced Virtual Energy Simulation Training and Research (AVESTARTM) Center. The Center was established as part of the DOE's accelerating initiative to advance new clean coal technology for power generation. IGCC systems are an attractive technology option, generating low-cost electricity by converting coal and/or other fuels into a clean synthesis gas mixture in a process that is efficient and environmentally superior to conventional power plants. The IGCC dynamic simulator builds on, and reaches beyond, conventional power plant simulators to merge, for the first time, a 'gasification with CO{sub 2} capture' process simulator with a 'combined-cycle' power simulator. Fueled with coal, petroleum coke, and/or biomass, the gasification island of the simulated IGCC plant consists of two oxygen-blown, downward-fired, entrained-flow, slagging gasifiers with radiant syngas coolers and two-stage sour shift reactors, followed by a dual-stage acid gas removal process for CO{sub 2} capture. The combined cycle island consists of two F-class gas turbines, steam turbine, and a heat recovery steam generator with three-pressure levels. The dynamic simulator can be used for normal base-load operation, as well as plant start-up and shut down. The real-time dynamic simulator also responds satisfactorily to process disturbances, feedstock blending and switchovers, fluctuations in ambient conditions, and power demand load shedding. In addition, the full-scope simulator handles a wide range of abnormal situations, including equipment malfunctions and failures, together with changes initiated through actions from plant field operators. By providing a comprehensive IGCC operator training system, the AVESTAR Center is poised to develop a workforce well-prepared to operate and control commercial-scale gasification-based power plants capable of 90% pre-combustion CO{sub 2} capture and compression, as well as low sulfur, mercury, and NOx emissions. With additional support from the NETL-Regional University Alliance (NETL-RUA), the Center will educate and train engineering students and researchers by providing hands-on 'learning by operating' experience The AVESTAR Center also offers unique collaborative R&D opportunities in high-fidelity dynamic modeling, advanced process control, real-time optimization, and virtual plant simulation. Objectives and goals are aimed at safe and effective management of power generation systems for optimal efficiency, while protecting the environment. To add another dimension of realism to the AVESTAR experience, NETL will introduce an immersive training system with innovative three-dimensional virtual reality technology. Wearing a stereoscopic headset or eyewear, trainees will enter an interactive virtual environment that will allow them to move freely throughout the simulated 3-D facility to study and learn various aspects of IGCC plant operation, control, and safety. Such combined operator and immersive training systems go beyond traditional simulation and include more realistic scenarios, improved communication, and collaboration among co-workers.

Zitney, S.; Liese, E.; Mahapatra, P.; Bhattacharyya, D.; Provost, G.

2011-01-01

340

Hybrid simulation modelling of the software process  

Microsoft Academic Search

The paper proposes the combination of three traditional modelling methods (analytical, continuous and discrete-event), into a unique hybrid two-level modelling approach, to address software process simulation modelling issues. At the higher abstraction level,

Paolo Donzelli; Giuseppe Iazeolla

2001-01-01

341

Tri-FAST Hardware-in-the-Loop Simulation. Volume I. Tri-Fast Hardware-in-the-Loop Simulation at the Advanced Simulation Center.  

National Technical Information Service (NTIS)

The purpose of this report is to document the Tri-FAST missile simulation development and the seeker hardware-in-the-loop (HWIL) testing in the Radio Frequency Simulation Cell of the Advanced Simulation Center (ASC). Tri-FAST is a tri-service active seeke...

D. B. Merriman, J. T. Taylo, R. C. Ward, C. R. Green

1979-01-01

342

Aeroacoustic simulation for phonation modeling  

NASA Astrophysics Data System (ADS)

The phonation process occurs as air expelled from the lungs creates a pressure drop and a subsequent air flow across the larynx. The fluid-structure interaction between the turbulent air flow and oscillating vocal folds, combined with additional resonance in the oral and nasal cavities, creates much of what we hear in the human voice. As many voice-related disorders can be traced to irregular vocal tract shape or motion, it is important to understand in detail the physics involved in the phonation process. To numerically compute the physics of phonation, a solver must be able to accurately model acoustic airflow through a moving domain. The open-source CFD package OpenFOAM is currently being used to evaluate existing solvers against simple acoustic test cases, including an open-ended resonator and an expansion chamber, both of which utilize boundary conditions simulating acoustic sources as well as anechoic termination. Results of these test cases will be presented and compared with theory, and the future development of a three-dimensional vocal tract model and custom-mode acoustic solver will be discussed.

Irwin, Jeffrey; Hanford, Amanda; Craven, Brent; Krane, Michael

2011-11-01

343

Advances in modeling wave particle interactions in the radiation belts  

NASA Astrophysics Data System (ADS)

We discuss the recent advances in simulations of the inner and outer radiation belts including radial, pitch-angle, energy, and mixed diffusio, and nno-lineaactions. Recently developed computer codes allow for qauntificaiton of the qussi-linear scattering due to day-side and night-side chorus waves, magneto-sonic waves, phasmaspheric hiss waves, EMIC and hiss waves in the regions of plumes, lightning generated whistlers, and anthropogenic whistlers. Sensitivity simulations show that the knowledge of wave spectral properties and spatial distribution of waves is crucially important for reproducing long term observations. The 3D simulations are compared to 3D reanalysis of the radiation belt fluxes that are obtained by blending the predictive model with observations from GEO, CRRES, Akebono, GPS and LANL. Recent research shows that similar processes may be responsible for acceleration and loss of energetic particles on the outer planet. Similar processes may be also important for acceleration and loss of particles on the Sun and solar wind and in other corners of the Universe.

Shprits, Yuri

2012-07-01

344

Development of CAPE-OPEN unit operations for advanced power systems modeling  

Microsoft Academic Search

Reaction Engineering International (REI) is developing a suite of CORBA CAPE-OPEN compliant unit operations to support the Department of Energy NETL Advanced Process Engineering Co-Simulation (APECS) framework for advanced power systems. One of these components will provide an interface to the GateCycle software, which is widely used in the power generation industry for process modeling. Additional CAPE-OPEN components will provide

D. Swensen; S. Zitney; M. Bockelie

2007-01-01

345

Simulation and modeling of cohesive powder flow  

Microsoft Academic Search

Simulation and modeling of the flow behavior of cohesive powders are carried out through discrete element simulation (DES) and the kinetic theory of gas-based continuum model to gain a fundamental understanding of the cohesive powder flows. The cohesive forces between particles, such as van der Waal's forces, are accounted for by particle surface energy through a microscopic contact force model.

Hong Shang

1998-01-01

346

Assessing range management alternatives using simulation models  

Microsoft Academic Search

A methodology is proposed to assist land managers in decision making using simulation models as a tool. Two modes of analysis, point in time and time series, are presented, but all examples use the point in time technique. Examples used the EPIC model as the simulation model. The methodology allows land manager to use current technology in the decision making

1986-01-01

347

User's manual for ADAM (Advanced Dynamic Airfoil Model)  

SciTech Connect

The computer code for an advanced dynamic airfoil model (ADAM) is described. The code is capable of calculating steady or unsteady flow over two-dimensional airfoils with allowances for boundary layer separation. Specific types of airfoil motions currently installed are steady rectilinear motion, impulsively started rectilinear motion, constant rate pitching, sinusoidal pitch oscillations, sinusoidal lateral plunging, and simulated Darrieus turbine motion. Other types of airfoil motion may be analyzed through simple modifications of a single subroutine. The code has a built-in capability to generate the geometric parameters for a cylinder, the NACA four-digit series of airfoils, and a NASA NLF-0416 laminar airfoil. Other types of airfoils are easily incorporated. The code ADAM is currently in a state of development. It is theoretically consistent and complete. However, further work is needed on the numerical implementation of the method.

Oler, J.W.; Strickland, J.H.; Im, B.J.

1987-06-01

348

Advanced Neutron Source Dynamic Model (ANSDM) code description and user guide  

SciTech Connect

A mathematical model is designed that simulates the dynamic behavior of the Advanced Neutron Source (ANS) reactor. Its main objective is to model important characteristics of the ANS systems as they are being designed, updated, and employed; its primary design goal, to aid in the development of safety and control features. During the simulations the model is also found to aid in making design decisions for thermal-hydraulic systems. Model components, empirical correlations, and model parameters are discussed; sample procedures are also given. Modifications are cited, and significant development and application efforts are noted focusing on examination of instrumentation required during and after accidents to ensure adequate monitoring during transient conditions.

March-Leuba, J.

1995-08-01

349

Iron Resources and Oceanic Nutrients: Advancement of Global Environment Simulations  

NASA Astrophysics Data System (ADS)

The concept of a single factor limiting plankton blooms, is presently giving way to co-limitation by light, and the nutrients N, P, Si and Fe. Primary production, export into the deep sea, and CO2 uptake from the atmosphere together form the 'biological pump' in Ocean Biogeochemical Climate Models (OBCM's). Thus far OBCM's assume just one limiting nutrient (P) and one universal phytoplankton species, for C budgets and CO2 exchange. New realistic OBCM's are being developed for budgeting and exchanges of both CO2 and DMS, implementing (i) co-limitation by 4 nutrients of 5 major taxonomic classes of phytoplankton, (ii) DMS(P) pathways, (iii) global iron cycling, (iv) chemical forms of iron and (v) iron supply into surface waters. The new OBCM's will predict realistic climate scenario's, notably climatic feedbacks on oceanic biogeochemistry. IRONAGES is a European consortium of twelve institutes and is coordinated by Royal NIOZ. Input from below of iron from anoxic sediments of coastal margins has been assessed (March 2002) along a 2-D vertical section from Europe into the centre of the north Atlantic. Input from above of Fe(II) dissolved in rainwater from Sahara dust blown over the central Atlantic will be quantified at sea (October 2002), and related to observed plankton production. Different chemical forms of iron are being assessed and a certification excercise for Fe in seawater also under aegis of SCOR Working Group 109 is being completed (December 2002). For two major DMS-producing algal groups Phaeocystis sp. and Emiliania huxleyi the life cycle, Fe limitation, export production, CO2 uptake and DMS emissions have been synthesized from existing literature and laboratory experiments. This is being fed into ecosystem modeling, as well as into DMS(P) pathway modeling. Also know-how has been synthesized for three other major classes (diatoms, N2-fixing Trichodesmium and nano-pico-plankton) and fed into the ecosystem modeling. Pathways of DMS(P) in blooms are being simulated. An existing plankton ecosystem model already well predicts limitation by four nutrients (N, P, Si, Fe) of two algal groups (diatoms and nanoplankton) including export and CO2 air/sea exchange. This is being expanded with 3 other groups of algae and DMS(P)pathways. Next this extended ecosystem model is being simplified while maintaining reliable output for export and CO2/DMS gas exchange. This unit will then be put into two existing OBCM's. Inputs of Fe from above and below into the oceans have been modeled. Moreover a simple global Fe cycling model has been verified versus field data and insights. Two different OBCM's with same upper ocean ecosystem/DMS unit and Fe cycling will be verified versus pre-industrial and present conditions. Next climate change scenario's, notably changes in Fe inputs, will be run, with special attention to climatic feedbacks (warming) on the oceanic cycles and fluxes.

Debaar, H. J.

2002-12-01

350

Software Platform Evaluation - Verifiable Fuel Cycle Simulation (VISION) Model  

SciTech Connect

The purpose of this Software Platform Evaluation (SPE) is to document the top-level evaluation of potential software platforms on which to construct a simulation model that satisfies the requirements for a Verifiable Fuel Cycle Simulation Model (VISION) of the Advanced Fuel Cycle (AFC). See the Software Requirements Specification for Verifiable Fuel Cycle Simulation (VISION) Model (INEEL/EXT-05-02643, Rev. 0) for a discussion of the objective and scope of the VISION model. VISION is intended to serve as a broad systems analysis and study tool applicable to work conducted as part of the AFCI (including costs estimates) and Generation IV reactor development studies. This document will serve as a guide for selecting the most appropriate software platform for VISION. This is a “living document” that will be modified over the course of the execution of this work.

J. J. Jacobson; D. E. Shropshire; W. B. West

2005-11-01

351

Real-Time Simulation Techniques Based on the RTO.k Object Modeling  

Microsoft Academic Search

Real-time simulation is an advanced mode of simulation in which the simulation objects are designed to show the same timing behavior that the simulation targets do. A new approach to real-time simulation which is based on the RTO.k object modeling is discussed in this paper. The RTO.k object, which is a real-time extension of the well-established object structure, is capable

K. H. Kim; Cuong Nguyen; Chan-mo Park

1996-01-01

352

Verification, validation and accreditation of simulation models  

Microsoft Academic Search

The paper discusses verification, validation, and accreditation of simulation models. The different approaches to deciding model validity are presented; how model verification and validation relate to the model development process are discussed; various validation techniques are defined; conceptual model validity, model verification, operational validity, and data validity are described; ways to document results are given; a recommended procedure is presented;

Robert G. Sargent

2000-01-01

353

Advanced numerical methods and software approaches for semiconductor device simulation  

SciTech Connect

In this article the authors concisely present several modern strategies that are applicable to drift-dominated carrier transport in higher-order deterministic models such as the drift-diffusion, hydrodynamic, and quantum hydrodynamic systems. The approaches include extensions of upwind and artificial dissipation schemes, generalization of the traditional Scharfetter-Gummel approach, Petrov-Galerkin and streamline-upwind Petrov Galerkin (SUPG), entropy variables, transformations, least-squares mixed methods and other stabilized Galerkin schemes such as Galerkin least squares and discontinuous Galerkin schemes. The treatment is representative rather than an exhaustive review and several schemes are mentioned only briefly with appropriate reference to the literature. Some of the methods have been applied to the semiconductor device problem while others are still in the early stages of development for this class of applications. They have included numerical examples from the recent research tests with some of the methods. A second aspect of the work deals with algorithms that employ unstructured grids in conjunction with adaptive refinement strategies. The full benefits of such approaches have not yet been developed in this application area and they emphasize the need for further work on analysis, data structures and software to support adaptivity. Finally, they briefly consider some aspects of software frameworks. These include dial-an-operator approaches such as that used in the industrial simulator PROPHET, and object-oriented software support such as those in the SANDIA National Laboratory framework SIERRA.

CAREY,GRAHAM F.; PARDHANANI,A.L.; BOVA,STEVEN W.

2000-03-23

354

Theory, Modeling, and Simulation of Semiconductor Lasers  

NASA Technical Reports Server (NTRS)

Semiconductor lasers play very important roles in many areas of information technology. In this talk, I will first give an overview of semiconductor laser theory. This will be followed by a description of different models and their shortcomings in modeling and simulation. Our recent efforts in constructing a fully space and time resolved simulation model will then be described. Simulation results based on our model will be presented. Finally the effort towards a self-consistent and comprehensive simulation capability for the opto-electronics integrated circuits (OEICs) will be briefly reviewed.

Ning, Cun-Zheng; Saini, Subbash (Technical Monitor)

1998-01-01

355

A direct-execution parallel architecture for the Advanced Continuous Simulation Language (ACSL)  

NASA Technical Reports Server (NTRS)

A direct-execution parallel architecture for the Advanced Continuous Simulation Language (ACSL) is presented which overcomes the traditional disadvantages of simulations executed on a digital computer. The incorporation of parallel processing allows the mapping of simulations into a digital computer to be done in the same inherently parallel manner as they are currently mapped onto an analog computer. The direct-execution format maximizes the efficiency of the executed code since the need for a high level language compiler is eliminated. Resolution is greatly increased over that which is available with an analog computer without the sacrifice in execution speed normally expected with digitial computer simulations. Although this report covers all aspects of the new architecture, key emphasis is placed on the processing element configuration and the microprogramming of the ACLS constructs. The execution times for all ACLS constructs are computed using a model of a processing element based on the AMD 29000 CPU and the AMD 29027 FPU. The increase in execution speed provided by parallel processing is exemplified by comparing the derived execution times of two ACSL programs with the execution times for the same programs executed on a similar sequential architecture.

Carroll, Chester C.; Owen, Jeffrey E.

1988-01-01

356

Modelling and simulation of a heat exchanger  

NASA Technical Reports Server (NTRS)

Two models for two different control systems are developed for a parallel heat exchanger. First by spatially lumping a heat exchanger model, a good approximate model which has a high system order is produced. Model reduction techniques are applied to these to obtain low order models that are suitable for dynamic analysis and control design. The simulation method is discussed to ensure a valid simulation result.

Xia, Lei; Deabreu-Garcia, J. Alex; Hartley, Tom T.

1991-01-01

357

ASUPT (Advanced Simulation in Undergraduate Pilot Training) Automated Objective Performance Measurement System.  

National Technical Information Service (NTIS)

To realize its full research potential a need exists for the development of an automated objective pilot performance evaluation system for use in the Advanced Simulation in Undergraduate Pilot Training (ASUPT) facility. The present report documents the ap...

W. L. Waag E. E. Eddowes J. H. Fuller R. R. Fuller

1975-01-01

358

Functional Requirements of an Advanced Instructional Design Advisor: Simulation Authoring. Volume 3.  

National Technical Information Service (NTIS)

The Advanced instructional Design Advisor (AIDA) will provide automated and intelligent assistance to inexperienced instructional computer-based instructional developers. This technical paper contains two reports discussing simulation capability and AIDA....

M. D. Merrill M. K. Jones D. M. Towne E. R. Nason

1992-01-01

359

Computer simulation and modeling in railway applications  

Microsoft Academic Search

An electrified railway system includes complex interconnections and interactions of several sub-systems. Computer simulation is the only viable means for system evaluation and analysis. This paper discusses the difficulties and requirements of effective simulation models for this specialized industrial application; and the development of a general-purpose multi-train simulator.

T. K. Ho; B. H. Mao; Z. Z. Yuan; H. D. Liu; Y. F. Fung

2002-01-01

360

Computer simulation and modeling in railway applications  

NASA Astrophysics Data System (ADS)

An electrified railway system includes complex interconnections and interactions of several sub-systems. Computer simulation is the only viable means for system evaluation and analysis. This paper discusses the difficulties and requirements of effective simulation models for this specialized industrial application; and the development of a general-purpose multi-train simulator.

Ho, T. K.; Mao, B. H.; Yuan, Z. Z.; Liu, H. D.; Fung, Y. F.

2002-02-01

361

Simulation of Thin-Film Damping and Thermal Mechanical Noise Spectra for Advanced Micromachined Microphone Structures  

PubMed Central

In many micromachined sensors the thin (2–10 ?m thick) air film between a compliant diaphragm and backplate electrode plays a dominant role in shaping both the dynamic and thermal noise characteristics of the device. Silicon microphone structures used in grating-based optical-interference microphones have recently been introduced that employ backplates with minimal area to achieve low damping and low thermal noise levels. Finite-element based modeling procedures based on 2-D discretization of the governing Reynolds equation are ideally suited for studying thin-film dynamics in such structures which utilize relatively complex backplate geometries. In this paper, the dynamic properties of both the diaphragm and thin air film are studied using a modal projection procedure in a commonly used finite element software and the results are used to simulate the dynamic frequency response of the coupled structure to internally generated electrostatic actuation pressure. The model is also extended to simulate thermal mechanical noise spectra of these advanced sensing structures. In all cases simulations are compared with measured data and show excellent agreement—demonstrating 0.8 pN/?Hz and 1.8 ?Pa/?Hz thermal force and thermal pressure noise levels, respectively, for the 1.5 mm diameter structures under study which have a fundamental diaphragm resonance-limited bandwidth near 20 kHz.

Hall, Neal A.; Okandan, Murat; Littrell, Robert; Bicen, Baris; Degertekin, F. Levent

2008-01-01

362

Simulation of Thin-Film Damping and Thermal Mechanical Noise Spectra for Advanced Micromachined Microphone Structures.  

PubMed

In many micromachined sensors the thin (2-10 ?m thick) air film between a compliant diaphragm and backplate electrode plays a dominant role in shaping both the dynamic and thermal noise characteristics of the device. Silicon microphone structures used in grating-based optical-interference microphones have recently been introduced that employ backplates with minimal area to achieve low damping and low thermal noise levels. Finite-element based modeling procedures based on 2-D discretization of the governing Reynolds equation are ideally suited for studying thin-film dynamics in such structures which utilize relatively complex backplate geometries. In this paper, the dynamic properties of both the diaphragm and thin air film are studied using a modal projection procedure in a commonly used finite element software and the results are used to simulate the dynamic frequency response of the coupled structure to internally generated electrostatic actuation pressure. The model is also extended to simulate thermal mechanical noise spectra of these advanced sensing structures. In all cases simulations are compared with measured data and show excellent agreement-demonstrating 0.8 pN/?Hz and 1.8 ?Pa/?Hz thermal force and thermal pressure noise levels, respectively, for the 1.5 mm diameter structures under study which have a fundamental diaphragm resonance-limited bandwidth near 20 kHz. PMID:19081811

Hall, Neal A; Okandan, Murat; Littrell, Robert; Bicen, Baris; Degertekin, F Levent

2008-06-01

363

Using LabVIEW ™ for advanced nonlinear optoelectronic device simulations in high-speed optical communications  

NASA Astrophysics Data System (ADS)

We present an advanced and comprehensive semiconductor optical amplifier model to analyze the propagation and amplification of 10 to, in principle, 1280 Gb/s ultra-short optical pulse sequences. Through appropriate transformation, the partial differential propagation-rate equation problem is numerically solved in a two-dimensional grid of fine resolution. The corresponding simulator, entirely programmed in the graphical language LabVIEW, is compared to an identical simulator implemented in the popular high-level text-based language Matlab. Special care has been taken to implement the same set of algorithms using equivalent codes for each language, such that a fair and objective one-to-one comparison can be carried out. In terms of computational time the LabVIEW simulator shows a tenfold outperformance, compared to its text-based identical counterpart implemented in Matlab, when typical bit sequences at 40 Gb/s with a length of 8 to 1024 bits are tested. The performance results presented here apply to a broader set of device modeling scenarios.

Gutiérrez-Castrejón, R.; Duelk, M.

2006-03-01

364

Advanced techniques and painless procedures for nonlinear contact analysis and forming simulation via implicit FEM  

NASA Astrophysics Data System (ADS)

Nonlinear contact analysis including forming simulation via finite element methods has a crucial and practical application in many engineering fields. However, because of high nonlinearity, nonlinear contact analysis still remains as an extremely challenging obstacle for many industrial applications. The implicit finite element scheme is generally more accurate than the explicit finite element scheme, but it has a known challenge of convergence because of complex geometries, large relative motion and rapid contact state change. It might be thought as a very painful process to diagnose the convergence issue of nonlinear contact. Most complicated contact models have a great many contact surfaces, and it is hard work to well define the contact pairs using the common contact definition methods, which either result in hundreds of contact pairs or are time-consuming. This paper presents the advanced techniques of nonlinear contact analysis and forming simulation via the implicit finite element scheme and the penalty method. The calculation of the default automatic contact stiffness is addressed. Furthermore, this paper presents the idea of selection groups to help easily and efficiently define contact pairs for complicated contact analysis, and the corresponding implementation and usage are discussed. Lastly, typical nonlinear contact models and forming models with nonlinear material models are shown in the paper to demonstrate the key presented method and technologies.

Zhuang, Shoubing

2013-05-01

365

A Generic Multibody Parachute Simulation Model  

NASA Technical Reports Server (NTRS)

Flight simulation of dynamic atmospheric vehicles with parachute systems is a complex task that is not easily modeled in many simulation frameworks. In the past, the performance of vehicles with parachutes was analyzed by simulations dedicated to parachute operations and were generally not used for any other portion of the vehicle flight trajectory. This approach required multiple simulation resources to completely analyze the performance of the vehicle. Recently, improved software engineering practices and increased computational power have allowed a single simulation to model the entire flight profile of a vehicle employing a parachute.

Neuhaus, Jason Richard; Kenney, Patrick Sean

2006-01-01

366

Advanced Nondestructive Evaluation (NDE) Sensor Modeling For Multisite Inspection.  

National Technical Information Service (NTIS)

The Advanced Nondestructive Evaluation (NDE) Sensor Modeling for Multisite Inspection program has developed finite element models (FEM) of electromagnetic NDE for optimizing the inspection of aging aircraft structure. The program found excellent correlati...

B. Koltenbah L. Udpa L. Xin R. Bossi Y. Deng

2008-01-01

367

Technology evaluation, assessment, modeling, and simulation: the TEAMS capability  

NASA Astrophysics Data System (ADS)

The United States Marine Corps' Technology Evaluation, Assessment, Modeling and Simulation (TEAMS) capability, located at the Naval Surface Warfare Center in Dahlgren Virginia, provides an environment for detailed test, evaluation, and assessment of live and simulated sensor and sensor-to-shooter systems for the joint warfare community. Frequent use of modeling and simulation allows for cost effective testing, bench-marking, and evaluation of various levels of sensors and sensor-to-shooter engagements. Interconnectivity to live, instrumented equipment operating in real battle space environments and to remote modeling and simulation facilities participating in advanced distributed simulations (ADS) exercises is available to support a wide- range of situational assessment requirements. TEAMS provides a valuable resource for a variety of users. Engineers, analysts, and other technology developers can use TEAMS to evaluate, assess and analyze tactical relevant phenomenological data on tactical situations. Expeditionary warfare and USMC concept developers can use the facility to support and execute advanced warfighting experiments (AWE) to better assess operational maneuver from the sea (OMFTS) concepts, doctrines, and technology developments. Developers can use the facility to support sensor system hardware, software and algorithm development as well as combat development, acquisition, and engineering processes. Test and evaluation specialists can use the facility to plan, assess, and augment their processes. This paper presents an overview of the TEAMS capability and focuses specifically on the technical challenges associated with the integration of live sensor hardware into a synthetic environment and how those challenges are being met. Existing sensors, recent experiments and facility specifications are featured.

Holland, Orgal T.; Stiegler, Robert L.

1998-08-01

368

Model Validation with Hybrid Dynamic Simulation  

SciTech Connect

Abstract—Model validation has been one of the central topics in power engineering studies for years. As model validation aims at obtaining reasonable models to represent actual behavior of power system components, it has been essential to validate models against actual measurements or known benchmark behavior. System-wide model simulation results can be compared with actual recordings. However, it is difficult to construct a simulation case for a large power system such as the WECC system and to narrow down to problematic models in a large system. Hybrid dynamic simulation with its capability of injecting external signals into dynamic simulation enables rigorous comparison of measurements and simulation in a small subsystem of interest. This paper presents such a model validation methodology with hybrid dynamic simulation. Two application examples on generator and load model validation are presented to show the validity of this model validation methodology. This methodology is further extended for automatic model validation and dichotomous subsystem model validation. A few methods to define model quality indices have been proposed to quantify model error for model validation criteria development.

Huang, Zhenyu; Kosterev, Dmitry; Guttromson, Ross T.; Nguyen, Tony B.

2006-06-22

369

Modelling the marine advance of the last Cordilleran ice sheet  

NASA Astrophysics Data System (ADS)

Marine advance of the last Cordilleran ice sheet onto the north-eastern Pacific continental shelf may have caused rapid fluctuations of sea level and potentially impacted upon human migration into North America. However the position of the former ice front was critically controlled by a process that remains poorly understood: glacier calving. Geomorphological reconstructions show that part of the presently oceanic areas were ice-covered, allowing for downstream formation of the well-studied Puget and Juan de Fuca lobes. Here we use a numerical glacier model (PISM) to reconstruct the former marine front of the Cordilleran ice sheet and its impact on upstream ice dynamics. Our simulations show that the use of a thickness-based calving law leads to a strong deficit of marine ice cover in the areas where existing reconstructions suggest its advance. In contrast, a physically-based parametrization of glacier calving using the main components of the strain rate tensor (eigencalving; A. Levermann, T. Albrecht, R. Winkelmann, M. A. Martin, M. Haseloff, and I. Joughin, The Cryosphere, 6, 273-286, 2012) reproduces the geomorphologically inferred ice extent.

Seguinot, Julien; Rogozhina, Irina

2014-05-01

370

Material Modeling for Terminal Ballistic Simulation.  

National Technical Information Service (NTIS)

Numerical simulation of terminal ballistic events requires quantitative modeling of the complex material responses which are observed to occur experimentally. This report discusses current deficiencies and future needs for material modeling in this contex...

G. Hauver, G. Randers-Pehrson, K. Kimsey, L. Magness, N. Huffington

1992-01-01

371

Comparison of climate model simulated and observed borehole temperature profiles  

NASA Astrophysics Data System (ADS)

Advances in understanding climate variability through the last millennium lean on simulation and reconstruction efforts. Progress in the integration of both approaches can potentially provide new means of assessing confidence on model projections of future climate change, of constraining the range of climate sensitivity and/or attributing past changes found in proxy evidence to external forcing. This work addresses specifically possible strategies for comparison of paleoclimate model simulations and the information recorded in borehole temperature profiles (BTPs). First efforts have allowed to design means of comparison of model simulated and observed BTPs in the context of the climate of the last millennium. This can be done by diffusing the simulated temperatures into the ground in order to produce synthetic BTPs that can be in turn assigned to collocated, real BTPs. Results suggest that there is sensitivity of borehole temperatures at large and regional scales to changes in external forcing over the last centuries. The comparison between borehole climate reconstructions and model simulations may also be subjected to non negligible uncertainties produced by the influence of past glacial and Holocene changes. While the thermal climate influence of the last deglaciation can be found well below 1000 m depth, such type of changes can potentially exert an influence on our understanding of subsurface climate in the top ca. 500 m. This issue is illustrated in control and externally forced climate simulations of the last millennium with the ECHO-G and LOVECLIM models, respectively.

Gonzalez-Rouco, J. F.; Stevens, M. B.; Beltrami, H.; Goosse, H.; Rath, V.; Zorita, E.; Smerdon, J.

2009-04-01

372

MODELLING AND SIMULATION OF STIMULI-RESPONSIVE HYDROGELS IN BIOMEMS  

Microsoft Academic Search

Mathematical modelling and numerical simulation are integral components in enabling the understanding the underlying physical and\\/or chemical mechanisms governing the vast array of complex material behaviors. This is especially so in advanced biomaterials such as bio-stimuli responsive hydrogels, which are widely used in BioMEMS devices. In these applications, multi- physics and multi-phase phenomena are commonly encountered. In the published studies

Hua Li; Teng Yong Ng; Khin Yong; Lam Nanyang

373

Coupling Advanced Atomistic Process and Device Modeling for Optimizing Future CMOS Devices  

Microsoft Academic Search

For the first time, we show the coupling between advanced atomistic process and device modeling and its applicability for 65nm PMOS and NMOS technology. This technique can be used to simulate and get some important insights to improve and optimize future CMOS devices

B. Colombeau; S. H. Yeong; S. M. Pandey; F. Benistant; M. Jaraiz; S. Chui

2006-01-01

374

ADVANCED FMEA USING META BEHAVIOR MODELING FOR CONCURRENT DESIGN OF PRODUCTS AND CONTROLS  

Microsoft Academic Search

This paper presents the use of Advanced Failure Modes and Effects Analysis (AFMEA) as a methodology for the concurrent design of electro-mecha nical products and their control systems. The past two years have seen the extension of AFMEA to simulate dynamic changes of device operations using meta-behavior modeling. This approach can help engineers identify failure modes associated with controls and

Steven Kmenta; Kosuke Ishii

1998-01-01

375

Harmonic balance optimization of terahertz Schottky diode multipliers using an advanced device model  

NASA Technical Reports Server (NTRS)

Substantial proress has been made recently in the advancement of solid state terahertz sources using chains of Schottky diode frequency multipliers. We have developed a harmonic balance simulator and corresponding diode model that incorporates many other factors participating in the diode behavior.

Schlecht, E. T.; Chattopadhyay, G.; Maestrini, A.; Pukala, D.; Gill, J.; Mehdi, I.

2002-01-01

376

Simulation model for competitive bidding in construction  

Microsoft Academic Search

In this paper, bidding optimization procedures are summarized for the construction context, and a model design is proposed for use in simulating the bidding process and its complexities. Situations involving potentially large numbers of bidders are represented. The simulation model incorporates the variety typically representative of projects for which bids are submitted, as well as the tendency of bidders to

John Seydel

1994-01-01

377

Animation of Complex Construction Simulation Models  

Microsoft Academic Search

One of the major impediments in using computer simulation to model and optimize construction processes has been the fact that decision makers often do not have the training nor the time to check the validity of simulation models prepared by others and thus have little confidence in the results. Animation is an increasingly popular technique that can be used to

Photios G. Ioannou; Julio Martinez

378

Development of Multi Agent Simulation Modeling System \\  

Microsoft Academic Search

The mathematical model of multi agent resource conversion processes (RCP) is developed by the means of discrete-event simulation systems and expert systems. Within the framework of mathematical model RCP are defined: production system of the RCP structure, that taking into account conflicts origin. The discrete-event simulation and expert system \\

Konstantin A. Aksyonov; Elena F. Smoliy; Natalia V. Goncharova; Alexey A. Khrenov

2007-01-01

379

Resist profile simulation with fast lithography model  

NASA Astrophysics Data System (ADS)

A traditional approach to construct a fast lithographic model is to match wafer top-down SEM images, contours and/or gauge CDs with a TCC model plus some simple resist representation. This modeling method has been proven and is extensively used for OPC modeling. As the technology moves forward, this traditional approach has become insufficient in regard to lithography weak point detection, etching bias prediction, etc. The drawback of this approach is from metrology and simulation. First, top-down SEM is only good for acquiring planar CD information. Some 3D metrology such as cross-section SEM or AFM is necessary to obtain the true resist profile. Second, the TCC modeling approach is only suitable for planar image simulation. In order to model the resist profile, full 3D image simulation is needed. Even though there are many rigorous simulators capable of catching the resist profile very well, none of them is feasible for full-chip application due to the tremendous consumption of computational resource. The authors have proposed a quasi-3D image simulation method in the previous study [1], which is suitable for full-chip simulation with the consideration of sidewall angles, to improve the model accuracy of planar models. In this paper, the quasi-3D image simulation is extended to directly model the resist profile with AFM and/or cross-section SEM data. Resist weak points detected by the model generated with this 3D approach are verified on the wafer.

He, Yan-Ying; Chou, Chih-Shiang; Tang, Yu-Po; Huang, Wen-Chun; Liu, Ru-Gun; Gau, Tsai-Sheng

2014-03-01

380

Study to Expand Simulation Cockpit Displays of Advanced Sensors.  

National Technical Information Service (NTIS)

This contractual effort was directed to the study to determine, examine and evaluate the cost and effectiveness of alternate methodologies for providing simulation capabilities of airborne sensor displays likely to be operational on combat aircraft throug...

J. Unterreiner D. L. Peters K. S. L. Setty

1981-01-01

381

Advanced Thermal Simulator Testing: Thermal Analysis and Test Results  

SciTech Connect

Work at the NASA Marshall Space Flight Center seeks to develop high fidelity, electrically heated thermal simulators that represent fuel elements in a nuclear reactor design to support non-nuclear testing applicable to the potential development of a space nuclear power or propulsion system. Comparison between the fuel pins and thermal simulators is made at the outer fuel clad surface, which corresponds to the outer sheath surface in the thermal simulator. The thermal simulators that are currently being tested correspond to a liquid metal cooled reactor design that could be applied for Lunar surface power. These simulators are designed to meet the geometric and power requirements of a proposed surface power reactor design, accommodate testing of various axial power profiles, and incorporate imbedded instrumentation. This paper reports the results of thermal simulator analysis and testing in a bare element configuration, which does not incorporate active heat removal, and testing in a water-cooled calorimeter designed to mimic the heat removal that would be experienced in a reactor core.

Bragg-Sitton, Shannon M.; Dickens, Ricky; Dixon, David; Reid, Robert; Adams, Mike; Davis, Joe [NASA Marshall Space Flight Center, Nuclear Systems Branch/ER24, MSFC, AL 35812 (United States)

2008-01-21

382

Advanced Thermal Simulator Testing: Thermal Analysis and Test Results  

NASA Technical Reports Server (NTRS)

Work at the NASA Marshall Space Flight Center seeks to develop high fidelity, electrically heated thermal simulators that represent fuel elements in a nuclear reactor design to support non-nuclear testing applicable to the development of a space nuclear power or propulsion system. Comparison between the fuel pins and thermal simulators is made at the outer fuel clad surface, which corresponds to the outer sheath surface in the thermal simulator. The thermal simulators that are currently being tested correspond to a SNAP derivative reactor design that could be applied for Lunar surface power. These simulators are designed to meet the geometric and power requirements of a proposed surface power reactor design, accommodate testing of various axial power profiles, and incorporate imbedded instrumentation. This paper reports the results of thermal simulator analysis and testing in a bare element configuration, which does not incorporate active heat removal, and testing in a water-cooled calorimeter designed to mimic the heat removal that would be experienced in a reactor core.

Bragg-Sitton, Shannon M.; Dickens, Ricky; Dixon, David; Reid, Robert; Adams, Mike; Davis, Joe

2008-01-01

383

A Computational Methodology for Simulating Thermal Loss Testing of the Advanced Stirling Convertor  

NASA Technical Reports Server (NTRS)

The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two highefficiency Advanced Stirling Convertors (ASCs), developed by Sunpower Inc. and NASA Glenn Research Center (GRC). The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot end and cold end temperatures, and specified electrical power output for a given net heat input. In an effort to improve net heat input predictions, numerous tasks have been performed which provided a more accurate value for net heat input into the ASCs, including the use of multidimensional numerical models. Validation test hardware has also been used to provide a direct comparison of numerical results and validate the multi-dimensional numerical models used to predict convertor net heat input and efficiency. These validation tests were designed to simulate the temperature profile of an operating Stirling convertor and resulted in a measured net heat input of 244.4 W. The methodology was applied to the multi-dimensional numerical model which resulted in a net heat input of 240.3 W. The computational methodology resulted in a value of net heat input that was 1.7 percent less than that measured during laboratory testing. The resulting computational methodology and results are discussed.

Reid, Terry V.; Wilson, Scott D.; Schifer, Nicholas A.; Briggs, Maxwell H.

2012-01-01

384

Development of Advanced Coatings for Laser Modifications Through Process and Materials Simulation  

NASA Astrophysics Data System (ADS)

A simulation-based system is currently being constructed to aid in the development of advanced coating systems for laser cladding and surface alloying. The system employs loosely coupled material and process models that allow rapid determination of material compatibility over a wide range of processing conditions. The primary emphasis is on the development and identification of composite coatings for improved wear and corrosion resistance. The material model utilizes computational thermodynamics and kinetic analysis to establish phase stability and extent of diffusional reactions that may result from the thermal response of the material during virtual processing. The process model is used to develop accurate thermal histories associated with the laser surface modification process and provides critical input for the non-isothermal materials simulations. These techniques were utilized to design a laser surface modification experiment that utilized the addition of stainless steel alloy 431 and TiC produced using argon and argon and nitrogen shielding. The deposits representing alloy 431 and TiC powder produced in argon resulted in microstructures retaining some TiC particles and an increase in hardness when compared to deposits produced using only the 431 powder. Laser deposits representing alloy 431 and TiC powder produced with a mixture of argon and nitrogen shielding gas resulted in microstructures retaining some TiC particles, as well as fine precipitates of Ti(CN) formed during cooling and a further increase in hardness of the deposit.

Martukanitz, R. P.; Babu, S. S.

2004-06-01

385

Material model validation for laser shock peening process simulation  

NASA Astrophysics Data System (ADS)

Advanced mechanical surface enhancement techniques have been used successfully to increase the fatigue life of metallic components. These techniques impart deep compressive residual stresses into the component to counter potentially damage-inducing tensile stresses generated under service loading. Laser shock peening (LSP) is an advanced mechanical surface enhancement technique used predominantly in the aircraft industry. To reduce costs and make the technique available on a large-scale basis for industrial applications, simulation of the LSP process is required. Accurate simulation of the LSP process is a challenging task, because the process has many parameters such as laser spot size, pressure profile and material model that must be precisely determined. This work focuses on investigating the appropriate material model that could be used in simulation and design. In the LSP process material is subjected to strain rates of 106 s-1, which is very high compared with conventional strain rates. The importance of an accurate material model increases because the material behaves significantly different at such high strain rates. This work investigates the effect of multiple nonlinear material models for representing the elastic-plastic behavior of materials. Elastic perfectly plastic, Johnson-Cook and Zerilli-Armstrong models are used, and the performance of each model is compared with available experimental results.

Amarchinta, H. K.; Grandhi, R. V.; Langer, K.; Stargel, D. S.

2009-01-01

386

Large Eddy Simulations and Turbulence Modeling for Film Cooling  

NASA Technical Reports Server (NTRS)

The objective of the research is to perform Direct Numerical Simulations (DNS) and Large Eddy Simulations (LES) for film cooling process, and to evaluate and improve advanced forms of the two equation turbulence models for turbine blade surface flow analysis. The DNS/LES were used to resolve the large eddies within the flow field near the coolant jet location. The work involved code development and applications of the codes developed to the film cooling problems. Five different codes were developed and utilized to perform this research. This report presented a summary of the development of the codes and their applications to analyze the turbulence properties at locations near coolant injection holes.

Acharya, Sumanta

1999-01-01

387

Psychometric and Evidentiary Advances, Opportunities, and Challenges for Simulation-Based Assessment  

ERIC Educational Resources Information Center

This article characterizes the advances, opportunities, and challenges for psychometrics of simulation-based assessments through a lens that views assessment as evidentiary reasoning. Simulation-based tasks offer the prospect for student experiences that differ from traditional assessment. Such tasks may be used to support evidentiary arguments…

Levy, Roy

2013-01-01

388

Improved rolling mill automation by means of advanced control techniques and dynamic simulation  

Microsoft Academic Search

This paper describes the simulation of a multiple-stand hot strip mill and its application for the development of complex control strategies. Both controlled system structure and control functions are explained. The application of advanced control techniques and dynamic simulation improves the thickness tolerances drastically. The results show that the major contribution stems from the feedforward system based on thickness and

Giinter W. Rigler; Heinrich R. Aberl; Wolfgang Staufer; Karl Aistleitner; Karl H. Weinberger

1996-01-01

389

Advanced Computer Simulations Of Nanomaterials And Stochastic Biological Processes  

NASA Astrophysics Data System (ADS)

This dissertation consists of several parts. The first two chapters are devoted to of study of dynamic processes in cellular organelles called filopodia. A stochastic kinetics approach is used to describe non-equilibrium evolution of the filopodial system from nano- to micro scales. Dynamic coupling between chemistry and mechanics is also taken into account in order to investigate the influence of focal adhesions on cell motility. The second chapter explores the possibilities and effects of motor enhanced delivery of actin monomers to the polymerizing tips of filopodia, and how the steady-state filopodial length can exceed the limit set by pure diffusion. Finally, we also challenge the currently existing view of active transport and propose a new theoretical model that accurately describes the motor dynamics and concentration profiles seen in experiments in a physically meaningful way. The third chapter is a result of collaboration between three laboratories, as a part of Energy Frontier Research Center at the University of North Carolina at Chapel Hill. The work presented here unified the fields of synthetic chemistry, photochemistry, and computational physical chemistry in order to investigate a novel bio-synthetic compound and its energy transfer capabilities. This particular peptide-based design has never been studied via Molecular Dynamics with high precision, and it is the first attempt known to us to simulate the whole chromophore-peptide complex in solution in order to gain detailed information about its structural and dynamic features. The fourth chapter deals with the non-equilibrium relaxation induced transport of water molecules in a microemulsion. This problem required a different set of methodologies and a more detailed, all-atomistic treatment of the system. We found interesting water clustering effects and elucidated the most probable mechanism of water transfer through oil under the condition of saturated Langmuir monolayers. Together these computational and theoretical studies compose a powerful and diverse set of physical approaches and both analytical and numerical methodologies, that can be successfully applied in the fields of biology, chemistry and biophysics.

Minakova, Maria S.

390

Numerical wind-speed simulation model  

SciTech Connect

A relatively simple stochastic model for simulating wind speed time series that can be used as an alternative to time series from representative locations is described in this report. The model incorporates systematic seasonal variation of the mean wind, its standard deviation, and the correlation speeds. It also incorporates systematic diurnal variation of the mean speed and standard deviation. To demonstrate the model capabilities, simulations were made using model parameters derived from data collected at the Hanford Meteorology Station, and results of analysis of simulated and actual data were compared.

Ramsdell, J.V.; Athey, G.F.; Ballinger, M.Y.

1981-09-01

391

A Distributed Simulation Facility to Support Human Factors Research in Advanced Air Transportation Technology  

NASA Technical Reports Server (NTRS)

A distributed real-time simulation of the civil air traffic environment developed to support human factors research in advanced air transportation technology is presented. The distributed environment is based on a custom simulation architecture designed for simplicity and flexibility in human experiments. Standard Internet protocols are used to create the distributed environment, linking all advanced cockpit simulator, all Air Traffic Control simulator, and a pseudo-aircraft control and simulation management station. The pseudo-aircraft control station also functions as a scenario design tool for coordinating human factors experiments. This station incorporates a pseudo-pilot interface designed to reduce workload for human operators piloting multiple aircraft simultaneously in real time. The application of this distributed simulation facility to support a study of the effect of shared information (via air-ground datalink) on pilot/controller shared situation awareness and re-route negotiation is also presented.

Amonlirdviman, Keith; Farley, Todd C.; Hansman, R. John, Jr.; Ladik, John F.; Sherer, Dana Z.

1998-01-01

392

Physically-based modeling and simulation of extraocular muscles.  

PubMed

Dynamic simulation of human eye movements, with realistic physical models of extraocular muscles (EOMs), may greatly advance our understanding of the complexities of the oculomotor system and aid in treatment of visuomotor disorders. In this paper we describe the first three dimensional (3D) biomechanical model which can simulate the dynamics of ocular motility at interactive rates. We represent EOMs using "strands", which are physical primitives that can model an EOM's complex nonlinear anatomical and physiological properties. Contact between the EOMs, the globe, and orbital structures can be explicitly modeled. Several studies were performed to assess the validity and utility of the model. EOM deformation during smooth pursuit was simulated and compared with published experimental data; the model reproduces qualitative features of the observed nonuniformity. The model is able to reproduce realistic saccadic trajectories when the lateral rectus muscle was driven by published measurements of abducens neuron discharge. Finally, acute superior oblique palsy, a pathological condition, was simulated to further evaluate the system behavior; the predicted deviation patterns agree qualitatively with experimental observations. This example also demonstrates potential clinical applications of such a model. PMID:20868704

Wei, Qi; Sueda, Shinjiro; Pai, Dinesh K

2010-12-01

393

Physically-based Modeling and Simulation of Extraocular Muscles  

PubMed Central

Dynamic simulation of human eye movements, with realistic physical models of extraocular muscles (EOMs), may greatly advance our understanding of the complexities of the oculomotor system and aid in treatment of visuomotor disorders. In this paper we describe the first three dimensional (3D) biomechanical model which can simulate the dynamics of ocular motility at interactive rates. We represent EOMs using “strands”, which are physical primitives that can model an EOM's complex nonlinear anatomical and physiological properties. Contact between the EOMs, the globe, and orbital structures can be explicitly modeled. Several studies were performed to assess the validity and utility of the model. EOM deformation during smooth pursuit was simulated and compared with published experimental data; the model reproduces qualitative features of the observed non-uniformity. The model is able to reproduce realistic saccadic trajectories when the lateral rectus muscle was driven by published measurements of abducens neuron discharge. Finally, acute superior oblique palsy, a pathological condition, was simulated to further evaluate the system behavior; the predicted deviation patterns agree qualitatively with experimental observations. This example also demonstrates potential clinical applications of such a model.

Wei, Qi; Sueda, Shinjiro; Pai, Dinesh K.

2010-01-01

394

Large blast and thermal simulator advanced concept driver design by computational fluid dynamics  

NASA Astrophysics Data System (ADS)

The construction of a large test facility is proposed for simulating the blast and thermal environment resulting from nuclear explosions. This facility would be used to test the survivability and vulnerability of military equipment such as trucks, tanks and helicopters in a simulated thermal and blast environment, and to perform research into nuclear blast phenomenology. The proposed advanced design concepts, heating of driver gas and fast-acting throat valves for wave shaping, are described and the results of CFD studies to advance these new technical concepts for simulating decaying blast waves are reported.

Opalka, Klaus O.

1989-08-01

395

Emulation of an Advanced G-Seat on the Advanced Simulator for Pilot Training.  

National Technical Information Service (NTIS)

An in-house effort was initiated to investigate simple G-seat hardware configurations for the purpose of developing a low-cost approach to G-cuing simulation in flight trainers. The G-seat is a motion and force simulation device which replaces the aircraf...

W. B. Albery D. C. McGuire

1978-01-01

396

Design and simulation of advanced fault tolerant flight control schemes  

NASA Astrophysics Data System (ADS)

This research effort describes the design and simulation of a distributed Neural Network (NN) based fault tolerant flight control scheme and the interface of the scheme within a simulation/visualization environment. The goal of the fault tolerant flight control scheme is to recover an aircraft from failures to its sensors or actuators. A commercially available simulation package, Aviator Visual Design Simulator (AVDS), was used for the purpose of simulation and visualization of the aircraft dynamics and the performance of the control schemes. For the purpose of the sensor failure detection, identification and accommodation (SFDIA) task, it is assumed that the pitch, roll and yaw rate gyros onboard are without physical redundancy. The task is accomplished through the use of a Main Neural Network (MNN) and a set of three De-Centralized Neural Networks (DNNs), providing analytical redundancy for the pitch, roll and yaw gyros. The purpose of the MNN is to detect a sensor failure while the purpose of the DNNs is to identify the failed sensor and then to provide failure accommodation. The actuator failure detection, identification and accommodation (AFDIA) scheme also features the MNN, for detection of actuator failures, along with three Neural Network Controllers (NNCs) for providing the compensating control surface deflections to neutralize the failure induced pitching, rolling and yawing moments. All NNs continue to train on-line, in addition to an offline trained baseline network structure, using the Extended Back-Propagation Algorithm (EBPA), with the flight data provided by the AVDS simulation package. The above mentioned adaptive flight control schemes have been traditionally implemented sequentially on a single computer. This research addresses the implementation of these fault tolerant flight control schemes on parallel and distributed computer architectures, using Berkeley Software Distribution (BSD) sockets and Message Passing Interface (MPI) for inter-process communication.

Gururajan, Srikanth

397

An emergency medical system simulation model  

Microsoft Academic Search

This paper presents a SIMSCRIPT simulation model designed for general use by health systems planners in evaluating existing or proposed emergency medical systems. An extensive validation of the model was performed using actual data from the San Fernando Valley area of Los Angeles. Appropriate operating procedures for use of the model are discussed. In conclusion, an application of the model

James A. Fitzsimmons

1971-01-01

398

Modeling and simulation of blood collection systems.  

PubMed

This paper addresses the modeling and simulation of blood collection systems in France for both fixed site and mobile blood collection with walk in whole blood donors and scheduled plasma and platelet donors. Petri net models are first proposed to precisely describe different blood collection processes, donor behaviors, their material/human resource requirements and relevant regulations. Petri net models are then enriched with quantitative modeling of donor arrivals, donor behaviors, activity times and resource capacity. Relevant performance indicators are defined. The resulting simulation models can be straightforwardly implemented with any simulation language. Numerical experiments are performed to show how the simulation models can be used to select, for different walk in donor arrival patterns, appropriate human resource planning and donor appointment strategies. PMID:22048940

Alfonso, Edgar; Xie, Xiaolan; Augusto, Vincent; Garraud, Olivier

2012-03-01

399

Simulation of equiaxed growth ahead of an advancing columnar front in directionally solidified Ni-based superalloys  

Microsoft Academic Search

Growth of equiaxed grains ahead of an advancing columnar front leads to the formation of as-cast defects, such as stray grains in single crystals or tree rings in vacuum arc remelting (VAR) ingots. In this study a combined cellular automata-finite difference model was applied to simulate dendrite growth and the formation of equiaxed grains in directionally solidified nickel-based superalloys. Realistic

H. B. Dong; X. L. Yang; P. D. Lee; W. Wang

2004-01-01

400

Current advance method and cyclic leapfrog for 2D multispecies hybrid plasma simulations  

NASA Astrophysics Data System (ADS)

CAM-CL (current advance method and cyclic leapfrog) is a new algorithm for hybrid plasma simulations. In common with existing methods, its physical basis is a 'hybrid' plasma model which treats the ions as particles and the electrons as a massless fluid. CAM-CL is distinguished from previous 2D hybrid algorithms by four main features: (1) Multiple ion species may be treated with only a single computational pass through the particle data: this is achieved without extrapolation of the electric field in time. The particles are advanced by a leapfrog procedure which requires the electric field to be half time-step ahead of the particle velocities. The electric field depends on the ionic current density and hence the particle velocities. In order to avoid a time-consuming 'pre-push' of the velocities, CAM advances the ionic current density a half-step with an appropriate equation of motion. This is similar in concept to the moment method (D. Winske and K. B. Quest, J. Geophys. Res. 93 (A9), 9681 (1988), Appendix A), except for the next two features: (2) CAM advances the ionic current density, whereas the moment method advances the fluid velocity. Consequently, multiple ion species may be easily treated. (3) A free-streaming ionic current density is collected (velocities are collected at positions a half time-step ahead). An equation of motion is then applied, in which the advective term and the ionic stress tensor in the moment method are not needed, since transport effects are included in the free-streaming current. (4) CL is a leapfrog scheme for advancing the magnetic field, an adaptation of the modified midpoint method described by W. H. Press et al. (Numerical Recipes (Cambridge Univ. Press, Cambridge, 1986)). It is stable and allows sub-stepping of the magnetic field (the magnetic field time-step may be different to the particle time-step). A two-dimensional version of the algorithm has been tested on a quiet plasma, MHD wave propogation, and ion beam instabilities, the results of which are discussed.

Matthews, Alan P.

1994-05-01

401

Current Advance Method and Cyclic Leapfrog for 2D Multispecies Hybrid Plasma Simulations  

NASA Astrophysics Data System (ADS)

CAM-CL (current advance method and cyclic leapfrog) is a new algorithm for hybrid plasma simulations. In common with existing methods, its physical basis is a "hybrid" plasma model which treats the ions as particles and the electrons as a massless fluid. CAM-CL is distinguished from previous 2D hybrid algorithms by four main features: (1) Multiple ion species may be treated with only a single computational pass through the particle data: this is achieved without extrapolation of the electric field in time. The particles are advanced by a leapfrog procedure which requires the electric field to be a half time-step ahead of the particle velocities. The electric field depends on the ionic current density and hence the particle velocities. In order to avoid a time-consuming "pre-push" of the velocities, CAM advances the ionic current density a half-step with an appropriate equation of motion. This is similar in concept to the moment method (D. Winske and K. B. Quest, J. Geophys, Res.93 (A9), 9681 (1988), Appendix A), except for the next two features: (2) CAM advances the ionic current density, whereas the moment method advances the fluid velocity. Consequently, multiple ion species may be easily treated (3) A free-streaming ionic current density is collected ( velocities are collected at positions a half time-step ahead). An equation of motion is then applied, in which the advective term and the ionic stress tensor in the moment method are not needed, since transport effects are included in the free-streaming current. (4) CL is a leapfrog scheme for advancing the magnetic field, an adaptation of the modified midpoint method described by W. H. Press et al. ( Numerical Recipes (Cambridge Univ. Press, Cambridge, 1986)). It is stable and allows sub-stepping of the magnetic field (the magnetic field time-step may be different to the particle time-step). A two-dimensional version of the algorithm has been tested on a quiet plasma, MHD wave propagation, and ion beam instabilities, the results of which are discussed.

Matthews, Alan P.

1994-05-01

402

Cross-Cultural Simulation to Advance Student Inquiry  

ERIC Educational Resources Information Center

This article reviews how and why the authors have used the cross-cultural simulation BAFA BAFA in a 1st-year social sciences inquiry course on social identity. The article discusses modifications made to Shirts's original script for BAFA BAFA, how the authors conduct the postsimulation debriefing, key aspects of the student-written reflection of…

Inglis, Sue; Sammon, Sheila; Justice, Christopher; Cuneo, Carl; Miller, Stefania; Rice, James; Roy, Dale; Warry, Wayne

2004-01-01

403

Antenna Arrays and Propagation Models for Advanced Wireless Systems  

Microsoft Academic Search

The development of advanced phased array antennas and new propagation models that address wireless applications in challenging propagation environments have and will continue to be a critically important component in the development of future wireless systems with applications in communications, radar, and Satellite technologies. In spite of the significant advances in these technologies, challenges continue to preclude their low cost,

Magdy F. Iskander; Zhengqing Yun; Nuri Celik; Jodie Bell; Wayne Kim

2007-01-01

404

Deterministic modelling and stochastic simulation of biochemical pathways using MATLAB.  

PubMed

The analysis of complex biochemical networks is conducted in two popular conceptual frameworks for modelling. The deterministic approach requires the solution of ordinary differential equations (ODEs, reaction rate equations) with concentrations as continuous state variables. The stochastic approach involves the simulation of differential-difference equations (chemical master equations, CMEs) with probabilities as variables. This is to generate counts of molecules for chemical species as realisations of random variables drawn from the probability distribution described by the CMEs. Although there are numerous tools available, many of them free, the modelling and simulation environment MATLAB is widely used in the physical and engineering sciences. We describe a collection of MATLAB functions to construct and solve ODEs for deterministic simulation and to implement realisations of CMEs for stochastic simulation using advanced MATLAB coding (Release 14). The program was successfully applied to pathway models from the literature for both cases. The results were compared to implementations using alternative tools for dynamic modelling and simulation of biochemical networks. The aim is to provide a concise set of MATLAB functions that encourage the experimentation with systems biology models. All the script files are available from www.sbi.uni-rostock.de/ publications_matlab-paper.html. PMID:16986253

Ullah, M; Schmidt, H; Cho, K H; Wolkenhauer, O

2006-03-01

405

Modeling based on work timing and numerical sense of power hardware-in-the-loop simulation  

Microsoft Academic Search

Power hardware-in-the-loop (PHIL) simulation is an advanced testing method with flexibility and fidelity. A PHIL system connects power hardware or physical models under test to a real-time simulator through an interface. This paper studies the basic and general theoretic analysis of PHIL simulation. Work timing, the base of PHIL simulation, is focused and studied in detail. Based on the timing,

Jun Ye; Yong Min

2011-01-01

406

Simulation model for the closed plant experiment facility of CEEF  

NASA Astrophysics Data System (ADS)

The Closed Ecology Experiment Facilities (CEEF) is a testbed for Controlled Ecological Life Support Systems (CELSS) investigations. CEEF including the physico-chemical material regenerative system has been constructed for the experiments of material circulation among plants, breeding animals and crew of CEEF. Because CEEF is a complex system, an appropriate schedule for the operation must be prepared in advance. The CEEF behavioral Prediction System, CPS, that will help to confirm the operation schedule, is under development. CPS will simulate CEEFs behavior with data (conditions of equipments, quantity of materials in tanks, etc.) of CEEF and an operation schedule that will be made by the operation team everyday, before the schedule will be carried out. The result of the simulation will show whether the operation schedule is appropriate or not. In order to realize CPS, models of the simulation program that is installed in CPS must mirror the real facilities of CEEF. For the first step of development, a flexible algorithm of the simulation program was investigated. The next step was development of a replicate simulation model of the material circulation system for the Closed Plant Experiment Facility (CPEF) that is a part of CEEF. All the parts of a real material circulation system for CPEF are connected together and work as a complex mechanism. In the simulation model, the system was separated into 38 units according to its operational segmentation. In order to develop each model for its corresponding unit, specifications for the model were fixed based on the specifications of the real part. These models were put into a simulation model for the system.

Abe, Koichi; Ishikawa, Yoshio; Kibe, Seishiro; Nitta, Keiji

407

Simulation of large-scale rule-based models  

SciTech Connect

Interactions of molecules, such as signaling proteins, with multiple binding sites and/or multiple sites of post-translational covalent modification can be modeled using reaction rules. Rules comprehensively, but implicitly, define the individual chemical species and reactions that molecular interactions can potentially generate. Although rules can be automatically processed to define a biochemical reaction network, the network implied by a set of rules is often too large to generate completely or to simulate using conventional procedures. To address this problem, we present DYNSTOC, a general-purpose tool for simulating rule-based models. DYNSTOC implements a null-event algorithm for simulating chemical reactions in a homogenous reaction compartment. The simulation method does not require that a reaction network be specified explicitly in advance, but rather takes advantage of the availability of the reaction rules in a rule-based specification of a network to determine if a randomly selected set of molecular components participates in a reaction during a time step. DYNSTOC reads reaction rules written in the BioNetGen language which is useful for modeling protein-protein interactions involved in signal transduction. The method of DYNSTOC is closely related to that of STOCHSIM. DYNSTOC differs from STOCHSIM by allowing for model specification in terms of BNGL, which extends the range of protein complexes that can be considered in a model. DYNSTOC enables the simulation of rule-based models that cannot be simulated by conventional methods. We demonstrate the ability of DYNSTOC to simulate models accounting for multisite phosphorylation and multivalent binding processes that are characterized by large numbers of reactions. DYNSTOC is free for non-commercial use. The C source code, supporting documentation and example input files are available at .

Hlavacek, William S [Los Alamos National Laboratory; Monnie, Michael I [Los Alamos National Laboratory; Colvin, Joshua [NON LANL; Faseder, James [NON LANL

2008-01-01

408

Software-Engineering Process Simulation (SEPS) model  

NASA Technical Reports Server (NTRS)

The Software Engineering Process Simulation (SEPS) model is described which was developed at JPL. SEPS is a dynamic simulation model of the software project development process. It uses the feedback principles of system dynamics to simulate the dynamic interactions among various software life cycle development activities and management decision making processes. The model is designed to be a planning tool to examine tradeoffs of cost, schedule, and functionality, and to test the implications of different managerial policies on a project's outcome. Furthermore, SEPS will enable software managers to gain a better understanding of the dynamics of software project development and perform postmodern assessments.

Lin, C. Y.; Abdel-Hamid, T.; Sherif, J. S.

1992-01-01

409

Simulation of a synergistic six-post motion system on the flight simulator for advanced aircraft at NASA-Ames  

NASA Technical Reports Server (NTRS)

Motion system drive philosophy and corresponding real-time software have been developed for the purpose of simulating the characteristics of a typical synergistic Six-Post Motion System (SPMS) on the Flight Simulator for Advanced Aircraft (FSAA) at NASA-Ames which is a non-synergistic motion system. This paper gives a brief description of these two types of motion systems and the general methods of producing motion cues of the FSAA. An actuator extension transformation which allows the simulation of a typical SPMS by appropriate drive washout and variable position limiting is described.

Bose, S. C.; Parris, B. L.

1977-01-01

410

Simulating data processing for an Advanced Ion Mobility Mass Spectrometer  

SciTech Connect

We have designed and implemented a Cray XD-1-based sim- ulation of data capture and signal processing for an ad- vanced Ion Mobility mass spectrometer (Hadamard trans- form Ion Mobility). Our simulation is a hybrid application that uses both an FPGA component and a CPU-based soft- ware component to simulate Ion Mobility mass spectrome- try data processing. The FPGA component includes data capture and accumulation, as well as a more sophisticated deconvolution algorithm based on a PNNL-developed en- hancement to standard Hadamard transform Ion Mobility spectrometry. The software portion is in charge of stream- ing data to the FPGA and collecting results. We expect the computational and memory addressing logic of the FPGA component to be portable to an instrument-attached FPGA board that can be interfaced with a Hadamard transform Ion Mobility mass spectrometer.

Chavarría-Miranda, Daniel; Clowers, Brian H.; Anderson, Gordon A.; Belov, Mikhail E.

2007-11-03

411

Advanced wellbore thermal simulator: GEOTEMP2 user manual  

SciTech Connect

GEOTEMP2 is a wellbore thermal simulator designed for geothermal well drilling and production problems. GEOTEMP2 includes the following features: fully transient heat conduction, wellbore fluid flow options, well completion options, and drilling-production histories. The data input format is given, along with input examples and comments on special features of the input. Ten examples that illustrate all of the flowing options and input options in GEOTEMP2 are included.

Mitchell, R.F.

1982-02-01

412

ADVANCES IN COMPREHENSIVE GYROKINETIC SIMULATIONS OF TRANSPORT IN TOKAMAKS  

SciTech Connect

A continuum global gyrokinetic code GYRO has been developed to comprehensively simulate core turbulent transport in actual experimental profiles and enable direct quantitative comparisons to the experimental transport flows. GYRO not only treats the now standard ion temperature gradient (ITG) mode turbulence, but also treats trapped and passing electrons with collisions and finite {beta}, equilibrium ExB shear stabilization, and all in real tokamak geometry. Most importantly the code operates at finite relative gyroradius ({rho}{sub *}) so as to treat the profile shear stabilization and nonlocal effects which can break gyroBohm scaling. The code operates in either a cyclic flux-tube limit (which allows only gyroBohm scaling) or a globally with physical profile variation. Rohm scaling of DIII-D L-mode has been simulated with power flows matching experiment within error bars on the ion temperature gradient. Mechanisms for broken gyroBohm scaling, neoclassical ion flows embedded in turbulence, turbulent dynamos and profile corrugations, plasma pinches and impurity flow, and simulations at fixed flow rather than fixed gradient are illustrated and discussed.

WALTZ RE; CANDY J; HINTON FL; ESTRADA-MILA C; KINSEY JE

2004-10-01

413

SIMULATION MODELING OF GASTROINTESTINAL ABSORPTION  

EPA Science Inventory

Mathematical dosimetry models incorporate mechanistic determinants of chemical disposition in a living organism to describe relationships between exposure concentration and the internal dose needed for PBPK models and human health risk assessment. Because they rely on determini...

414

Advances in Modeling Visual Search and Target Discrimination Performance.  

National Technical Information Service (NTIS)

This paper reports on advances in mathematical models of observer- ensemble performance in narrow-field- of-view visual search and target discrimination for ground vehicles in natural terrain. Three developments are presented. We show that the distributio...

D. J. Gorsich G. Witus G. R. Gerhart R. E. Karlsen

2002-01-01

415

Advancing Software Architecture Modeling for Large Scale Heterogeneous Systems  

SciTech Connect

In this paper we describe how incorporating technology-specific modeling at the architecture level can help reduce risks and produce better designs for large, heterogeneous software applications. We draw an analogy with established modeling approaches in scientific domains, using groundwater modeling as an example, to help illustrate gaps in current software architecture modeling approaches. We then describe the advances in modeling, analysis and tooling that are required to bring sophisticated modeling and development methods within reach of software architects.

Gorton, Ian; Liu, Yan

2010-11-07

416

Modeling Physics with Easy Java Simulations  

NSDL National Science Digital Library

The paper Modeling Physics with Easy Java Simulations describes the use of the Easy Java Simulations (Ejs) modeling and authoring tool and shows how this tool can be used to teach mechanics concepts using computer modeling. Although the modeling method can be used without computers, the use of computers allows students to study problems that are difficult and time consuming, to visualize their results, and to communicate their results with others. The combination of computer modeling with theory and experiment can achieve insight and understanding that cannot be achieved with only one approach. Journal article available from http://scitation.aip.org/tpt/

Christian, Wolfgang; Franciscouembre

2008-05-30

417

Numerical Simulation of Unsteady Aerodynamic Models  

NASA Technical Reports Server (NTRS)

This report documents the results of the numerical simulations of unsteady aerodynamic models. The results focus on numerical accuracy and efficiency, and the robustness of the numerical methods. The aerodynamic models includes the classical Wagner and Kussner functions and the Leishman-Beddoes dynamic stall model. The simulations includes the numerical approximations of the Duhamel's integrals using both indicial (step) and impulse responses, the numerical integrations of the state-space models, and the exact solutions. The report also presents the conversion among different model representations.

Nguyen, Khanh Q.; Warmbrodt, William (Technical Monitor)

1997-01-01

418

A Stochastic Simulation Model Of Family Income  

Microsoft Academic Search

This paper describes a stochastic simulation model of family income. Our goal is to implement a stochastic simulation experiment which provides an alternative view on the declining trend of U.S. real family income suggested in the joint study by The Children's Defense Fund and The Northeastern University's Center For Labor Studies. Thus, a major part of this paper is the

Jonathan Huntley; David Tepper; Thomas Wong

1993-01-01

419

The simulation of a jumbo jet transport aircraft. Volume 2: Modeling data  

NASA Technical Reports Server (NTRS)

The manned simulation of a large transport aircraft is described. Aircraft and systems data necessary to implement the mathematical model described in Volume I and a discussion of how these data are used in model are presented. The results of the real-time computations in the NASA Ames Research Center Flight Simulator for Advanced Aircraft are shown and compared to flight test data and to the results obtained in a training simulator known to be satisfactory.

Hanke, C. R.; Nordwall, D. R.

1970-01-01

420

Advanced EMI Modeling and Processing Approaches for UXO Discrimination  

Microsoft Academic Search

This paper presents a new, advanced non-traditional physics based inverse-scattering approach for determining a buried object's location and orientation. The approach combines an advanced electromagnetic induction (EMI) forward model called the normalized surface magnetic charge model (NSMC) with the pole series expansions technique. First, the NSMC is used to generate bi-static EMI data from actual measured mono-static data, and then

F. Shubitidze; B. Barrowes; K. O'Neill; I. Shamatava

2006-01-01

421

Advances in Acoustic Modeling for the Recognition of Czech  

Microsoft Academic Search

This paper presents recent advances in Automatic Speech Recognition for the Czech Language. Improvements were achieved both\\u000a in acoustic and language modeling. We mainly aim on the acoustic part of the issue. The results are presented in two contexts,\\u000a the lecture recognition and SpeeCon+Temic test set. The paper shows the impact of using advanced modeling techniques such\\u000a as HLDA, VTLN

Jirí Kopecký; Ondrej Glembek; Martin Karafiát

2008-01-01

422

Seismic Simulations Using Parallel Computing and Three-Dimensional Earth Models to Improve Nuclear Explosion Phenomenology and Monitoring.  

National Technical Information Service (NTIS)

The development of accurate numerical methods to simulate wave propagation in three-dimensional (3D) earth models and advances in computational power offer exciting possibilities for modeling the motions excited by underground nuclear explosions. This pre...

A. Petersson A. J. Rodgers B. A. Sjogreen E. Matzel M. E. Pasyanos

2008-01-01