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Sample records for heterogeneity-a simulation study

  1. Grab vs. composite sampling of particulate materials with significant spatial heterogeneity--a simulation study of "correct sampling errors".

    Science.gov (United States)

    Minkkinen, Pentti O; Esbensen, Kim H

    2009-10-19

    Sampling errors can be divided into two classes, incorrect sampling and correct sampling errors. Incorrect sampling errors arise from incorrectly designed sampling equipment or procedures. Correct sampling errors are due to the heterogeneity of the material in sampling targets. Excluding the incorrect sampling errors, which can all be eliminated in practice although informed and diligent work is often needed, five factors dominate sampling variance: two factors related to material heterogeneity (analyte concentration; distributional heterogeneity) and three factors related to the sampling process itself (sample type, sample size, sampling modus). Due to highly significant interactions, a comprehensive appreciation of their combined effects is far from trivial and has in fact never been illustrated in detail. Heterogeneous materials can be well characterized by the two first factors, while all essential sampling process characteristics can be summarized by combinations of the latter three. We here present simulations based on an experimental design that varies all five factors. Within the framework of the Theory of Sampling, the empirical Total Sampling Error is a function of the fundamental sampling error and the grouping and segregation error interacting with a specific sampling process. We here illustrate absolute and relative sampling variance levels resulting from a wide array of simulated repeated samplings and express the effects by pertinent lot mean estimates and associated Root Mean Squared Errors/sampling variances, covering specific combinations of materials' heterogeneity and typical sampling procedures as used in current science, technology and industry. Factors, levels and interactions are varied within limits selected to match realistic materials and sampling situations that mimic, e.g., sampling for genetically modified organisms; sampling of geological drill cores; sampling during off-loading 3-dimensional lots (shiploads, railroad cars, truckloads

  2. Surface heterogeneity: a friend or foe of protein adsorption - insights from theoretical simulations.

    Science.gov (United States)

    Penna, Matthew; Ley, Kamron; Maclaughlin, Shane; Yarovsky, Irene

    2016-10-06

    A lack in the detailed understanding of mechanisms through which proteins adsorb or are repelled at various solid/liquid interfaces limits the capacity to rationally design and produce more sophisticated surfaces with controlled protein adsorption in both biomedical and industrial settings. To date there are three main approaches to achieve anti biofouling efficacy, namely chemically adjusting the surface hydrophobicity and introducing various degrees of surface roughness, or a combination of both. More recently, surface nanostructuring has been shown to have an effect on protein adsorption. However, the current resolution of experimental techniques makes it difficult to investigate these three phase systems at the molecular level. In this molecular dynamics study we explore in all-atom detail the adsorption process of one of the most surface active proteins, EAS hydrophobin, known for its versatile ability to self-assemble on both hydrophobic and hydrophilic surfaces forming stable monolayers that facilitate further biofilm growth. We model the adsorption of this protein on organic ligand protected silica surfaces with varying degrees of chemical heterogeneity and roughness, including fully homogenous hydrophobic and hydrophilic surfaces for comparison. We present a detailed characterisation of the functionalised surface structure and dynamics for each of these systems, and the effect the ligands have on interfacial water, the adsorption process and conformational rearrangements of the protein. Results suggest that the ligand arrangement that produces the highest hydrophilic chain mobility and the lack of significant hydrophobic patches shows the most promising anti-fouling efficacy toward hydrophobin. However, the presence on the protein surface of a flexible loop with amphipathic character (the Cys3-Cys4 loop) is seen to facilitate EAS adsorption on all surfaces by enabling the protein to match the surface pattern.

  3. Shocking of metallic glass to induce microstructure heterogeneity: A molecular dynamics study

    Science.gov (United States)

    Ma, Chi; Wang, Guo-Xiang; Ye, Chang; Dong, Yalin

    2017-09-01

    Surface severe plastic deformation (SSPD) has been demonstrated to improve the ductility of metallic glass. The physical interpretation, however, remains on the phenomenological level. In this study, a molecular dynamics (MD) simulation is carried out to elucidate the molecular mechanisms underlying the improvement in ductility. MD simulation reveals that shock waves resulting from SSPD can induce pre-deformed atoms, which are randomly embedded in the matrix of the metallic glass. The pre-deformed atoms have similar stress distribution and short-order structure as the matrix atoms, but with a larger atomic volume. When subjected to tensile or compressive stress, more shear bands are promoted by the pre-deformed atoms in the shock-treated sample as compared to the untreated one. The randomly distributed shear bands were found to experience more interactions, which delayed the catastrophic fracture, leading to increased ductility.

  4. Characterizing permafrost active layer dynamics and sensitivity to landscape spatial heterogeneity: A case study in Alaska

    Science.gov (United States)

    Yi, Y.; Kimball, J. S.; Moghaddam, M.; Reichle, R. H.

    2016-12-01

    An important feature of the Arctic is the large spatial heterogeneity in permafrost and active layer conditions, which are generally poorly represented in global climate and carbon models and can lead to large uncertainties in predicting regional ecosystem responses and feedbacks to climate change. In this study, we developed a spatially integrated analysis and modeling framework to investigate the sensitivity of permafrost active layer processes to sub-grid heterogeneity in vegetation, terrain and disturbance factors. The model framework combines detailed field measurements of vegetation, microclimate and active layer properties with local scale ( 100m resolution) soil active layer retrievals from airborne radar remote sensing, and landscape level (≥1-km resolution) environmental observations from satellite microwave and optical-infrared sensors. Satellite observations, including land surface temperature, snow cover extent and soil moisture from the MODIS and SMAP sensors, are used as primary model drivers for estimating snow/soil thermal conductivity and soil temperature profiles. The model estimates regional patterns and recent changes (2001-present) in permafrost extent (PE) and ALT across Alaska at landscape scale ( 1-km resolution). Local scale maps of active layer conditions and additional land parameters include soil moisture and surface organic layer thickness from combined low frequency (L+P-band) airborne radar backscatter from the NASA UAVSAR and AirMOSS sensors will be used to inform the coarser landscape model simulations and quantify the effects of surface organic layer and soil moisture spatial heterogeneity on the estimated soil active layer dynamics. These results are used to clarify regional patterns and recent changes in permafrost active layer conditions, and underlying environmental controls across Alaska.

  5. Park size and disturbance: impact on soil heterogeneity - a case study Tel-Aviv- Jaffa.

    Science.gov (United States)

    Zhevelev, Helena; Sarah, Pariente; Oz, Atar

    2015-04-01

    Parks and gardens are poly-functional elements of great importance in urban areas, and can be used for optimization of physical and social components in these areas. This study aimed to investigate alteration of soil properties with land usages within urban park and with area size of park. Ten parks differed by size (2 - 50 acres) were chosen, in random, in Tel-Aviv- Jaffa city. Soil was sampled in four microenvironments ((lawn, path, picnic and peripheral area (unorganized area) of each the park)), in three points and three depth (0-2, 5-10 and 10-20 cm). Penetration depth was measured in all point of sampling. For each soil sample electrical conductivity and organic matter content were determined. Averages of penetration depth drastically increased from the most disturbed microenvironments (path and picnic) to the less disturbed ones (lawn and peripheral). The maximal heterogeneity (by variances and percentiles) of penetration depth was found in the peripheral area. In this area, penetration depth increased with increasing park size, i.e., from 2.6 cm to 3.7 cm in the small and large parks, respectively. Averages of organic matter content and electrical conductivity decreased with soil depth in all microenvironments and increased with decreasing disturbance of microenvironments. Maximal heterogeneity for both of these properties was found in the picnic area. Increase of park size was accompanied by increasing of organic matter content in the upper depth in the peripheral area, i.e., from 2.4% in the small parks to 4.5% in the large ones. In all microenvironments the increasing of averages of all studied soil properties was accompanied by increasing heterogeneity, i.e., variances and upper percentiles. The increase in the heterogeneity of the studied soil properties is attributed to improved ecological soil status in the peripheral area, on the one hand, and to the high anthropogenic pressure in the picnic area, on the other. This means that the urban park offers

  6. Bayesian Modeling for Genetic Anticipation in Presence of Mutational Heterogeneity: A Case Study in Lynch Syndrome

    DEFF Research Database (Denmark)

    Boonstra, Philip S; Mukherjee, Bhramar; Taylor, Jeremy M G

    2011-01-01

    Summary Genetic anticipation, described by earlier age of onset (AOO) and more aggressive symptoms in successive generations, is a phenomenon noted in certain hereditary diseases. Its extent may vary between families and/or between mutation subtypes known to be associated with the disease phenotype...... inferential conclusions. We compare the fit of four-candidate random effects distributions via Bayesian model fit diagnostics. A related statistical issue here is isolating the confounding effect of changes in secular trends, screening, and medical practices that may affect time to disease detection across...... birth cohorts. Using historic cancer registry data, we borrow from relative survival analysis methods to adjust for changes in age-specific incidence across birth cohorts. Our motivating case study comes from a Danish cancer register of 124 families with mutations in mismatch repair (MMR) genes known...

  7. Conducting Simulation Studies in Psychometrics

    Science.gov (United States)

    Feinberg, Richard A.; Rubright, Jonathan D.

    2016-01-01

    Simulation studies are fundamental to psychometric discourse and play a crucial role in operational and academic research. Yet, resources for psychometricians interested in conducting simulations are scarce. This Instructional Topics in Educational Measurement Series (ITEMS) module is meant to address this deficiency by providing a comprehensive…

  8. Population expanding with the phalanx model and lineages split by environmental heterogeneity: a case study of Primula obconica in subtropical China.

    Directory of Open Access Journals (Sweden)

    Hai-Fei Yan

    Full Text Available BACKGROUND: Current and historical events have both affected the current distribution patterns and intraspecific divergence of plants. While numerous studies have focused on the Qinghai-Tibetan Plateau (QTP, the impacts of such events on the flora of subtropical China remain poorly understood. Subtropical China is famous for its highly complex topography and the limited impact from glaciation during the Pleistocene; this may have resulted in a different genetic legacy for species in this region compared to fully glaciated areas. METHODOLOGY/PRINCIPAL FINDINGS: We used plastid and nuclear DNA sequence data and distribution modeling to analyze the divergence patterns and demographic history of Primula obconica Hance, a widespread herbaceous montane species in subtropical China. The phylogenetic analysis revealed two major lineages (lineage A and lineage B, representing a west-east split into the Yunnan and Eastern groups, and the Sichuan and Central groups, respectively. The Eastern and Central groups comprised relatively new derived haplotypes. Nested Clade Analysis and Bayesian Skyline Plot analyses both indicated that P. obconica mainly experienced a gradual expansion of populations. In addition, the simulated distribution of P. obconica during the Last Glacial Maximum was slightly larger than its present-day distribution. CONCLUSION/SIGNIFICANCE: Our results are the first to identify a west-east migration of P. obconica. The gradual expansion pattern and a larger potential distribution range in cold periods detected for P. obconica indicate that the population expansion of this species is consistent with the phalanx model. In addition, the current patterns of genetic differentiation have persisted as a result of the extensive environmental heterogeneity that exists in subtropical China.

  9. Microgrid Modeling and Simulation Study

    Science.gov (United States)

    2016-09-01

    lightning , and other scenarios need to be simulated and hardware tested to characterize system robustness. The reviewed M&S tools were divided into the...5 capability categories for tactical microgrids: Demand Management, Power Distribution, Source Management, Communications, and Smart Controls. In...requires a short-term investment to produce results. • Component Metadata is the use of digital information from equipment for microgrid Smart

  10. Simulations & Case Studies. [SITE 2002 Section].

    Science.gov (United States)

    Seymour, Cathy R., Ed.

    This document contains the following papers on simulations and case studies from the SITE (Society for Information Technology & Teacher Education) 2002 conference: "3-D Virtual Classroom Technology" (Kimberly Arseneau Miller, Angela Glod); "Simulated Lesson Design Studios" (Willis Copeland); "Lights, Camera, Integration: Presentation Programs and…

  11. Crop micrometeorology : a simulation study

    NARCIS (Netherlands)

    Goudriaan, J.

    1977-01-01

    This monograph presents the results of a detailed study in micrometeorology; one of the sciences that play an important role in production ecology. The purpose is to explain the microweather as a function of the properties of plant and soil, and of the weather conditions prevalent at some

  12. preliminary multidomain modelling and simulation study

    African Journals Online (AJOL)

    user

    PRELIMINARY MULTIDOMAIN MODELLING AND SIMULATION STUDY OF A. HORIZONTAL AXIS WIND TURBINE (HAWT) TOWER VIBRATION. I. lliyasu1, I. Iliyasu2, I. K. Tanimu3 and D. O Obada4. 1,4 DEPARTMENT OF MECHANICAL ENGINEERING, AHMADU BELLO UNIVERSITY, ZARIA, KADUNA STATE. NIGERIA.

  13. Study of Cardiac Defibrillation Through Numerical Simulations

    Science.gov (United States)

    Bragard, J.; Marin, S.; Cherry, E. M.; Fenton, F. H.

    Three-dimensional numerical simulations of the defibrillation problem are presented. In particular, in this study we use the rabbit ventricular geometry as a realistic model system for evaluating the efficacy of defibrillatory shocks. Statistical data obtained from the simulations were analyzed in term of a dose-response curve. Good quantitative agreement between our numerical results and clinically relevant values is obtained. An electric field strength of about 6.6 V/cm indicates a fifty percent probability of successful defibrillation for a 12-ms monophasic shock. Our validated model will be useful for optimizing defibrillation protocols.

  14. Simulated patient studies: an ethical analysis.

    Science.gov (United States)

    Rhodes, Karin V; Miller, Franklin G

    2012-12-01

    In connection with health care reform, the U.S. Department of Health and Human Services commissioned a "mystery shopper," or simulated patient study, to measure access to primary care. But the study was shelved because of public controversy over "government spying" on doctors. Opponents of the study also raised ethical concerns about the use of deception with human subjects without soliciting their informed consent. We undertook an ethical analysis of the use of simulated patient techniques in health services research, with a particular focus on research measuring access to care. Using a case study, we explored relevant methodological considerations and ethical principles relating to deceptive research without informed consent, as well as U.S. federal regulations permitting exceptions to consent. Several relevant considerations both favor and oppose soliciting consent for simulated patient studies. Making research participation conditional on informed consent protects the autonomy of research subjects and shields them from unreasonable exposure to research risks. However, scientific validity is also an important ethical principle of human subjects research, as the net risks to subjects must be justified by the value to society of the knowledge to be gained. The use of simulated patients to monitor access is a naturalistic and scientifically sound experimental design that can answer important policy-relevant questions, with minimal risks to human subjects. As interaction between researchers and subjects increases, however, so does the need for consent. As long as adequate protections of confidentiality of research data are in place, minimally intrusive simulated patient research that gathers policy-relevant data on the health system without the consent of individuals working in that system can be ethically justified when the risks and burdens to research subjects are minimal and the research has the potential to generate socially valuable knowledge. © 2012 Milbank

  15. Molecular dynamics simulation study of methanesulfonic acid

    OpenAIRE

    Canales Gabriel, Manel; Alemán Llansó, Carlos

    2014-01-01

    A molecular dynamics simulation study of methanesulfonic acid has been carried out using a reliable force field in a large range of temperatures. Several thermodynamic, structural, and dynamical properties have been calculated and compared with the available experimental data. The density, the shear viscosity, the heat of vaporization, and the melting temperature results, calculated from this force field, are in a good agreement with the experimental data. Analysis of the influence of the hyd...

  16. Vertical Jump: Biomechanical Analysis and Simulation Study

    OpenAIRE

    Babic, Jan; Lenarcic, Jadran

    2007-01-01

    By building an efficient biorobotic model which includes an elastic model of the biarticular muscle gastrocnemius and by simulation of the vertical jump we have demonstrated that biarticular links contribute a great deal to the performance of the vertical jump. Besides, we have shown that timing of the biarticular link activation and stiffness of the biarticular link considerably influence the height of the jump. Methodology and results of our study offer an effective tool for the design of t...

  17. Mobile-ip Aeronautical Network Simulation Study

    Science.gov (United States)

    Ivancic, William D.; Tran, Diepchi T.

    2001-01-01

    NASA is interested in applying mobile Internet protocol (mobile-ip) technologies to its space and aeronautics programs. In particular, mobile-ip will play a major role in the Advanced Aeronautic Transportation Technology (AATT), the Weather Information Communication (WINCOMM), and the Small Aircraft Transportation System (SATS) aeronautics programs. This report presents the results of a simulation study of mobile-ip for an aeronautical network. The study was performed to determine the performance of the transmission control protocol (TCP) in a mobile-ip environment and to gain an understanding of how long delays, handoffs, and noisy channels affect mobile-ip performance.

  18. A simulation study on garment manufacturing process

    Science.gov (United States)

    Liong, Choong-Yeun; Rahim, Nur Azreen Abdul

    2015-02-01

    Garment industry is an important industry and continues to evolve in order to meet the consumers' high demands. Therefore, elements of innovation and improvement are important. In this work, research studies were conducted at a local company in order to model the sewing process of clothes manufacturing by using simulation modeling. Clothes manufacturing at the company involves 14 main processes, which are connecting the pattern, center sewing and side neating, pockets sewing, backside-sewing, attaching the front and back, sleeves preparation, attaching the sleeves and over lock, collar preparation, collar sewing, bottomedge sewing, buttonholing sewing, removing excess thread, marking button, and button cross sewing. Those fourteen processes are operated by six tailors only. The last four sets of processes are done by a single tailor. Data collection was conducted by on site observation and the probability distribution of processing time for each of the processes is determined by using @Risk's Bestfit. Then a simulation model is developed using Arena Software based on the data collected. Animated simulation model is developed in order to facilitate understanding and verifying that the model represents the actual system. With such model, what if analysis and different scenarios of operations can be experimented with virtually. The animation and improvement models will be presented in further work.

  19. OpenSimulator Interoperability with DRDC Simulation Tools: Compatibility Study

    Science.gov (United States)

    2014-09-01

    Cinema 4D, 3D Studio Max, Cheetah3D, Modo, Lightwave and Blender. Intergraph’s SmartMarine 3D and SmartPlant 3D ship and plant design software...modeling and animation software, 3D Studio Max (3DS Max) is a ubiquitous and common application for the development of 3D assets for gaming and simulation...to COLLADA using SketchUp The 3D modeling and animation software, SketchUp (owned by Google between 2006 and 2012, now by Trimble Navigation) is

  20. DWPF simulant CPC studies for SB8

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D. C.; Zamecnik, J. R.

    2013-06-25

    The Savannah River National Laboratory (SRNL) accepted a technical task request (TTR) from Waste Solidification Engineering to perform simulant tests to support the qualification of Sludge Batch 8 (SB8) and to develop the flowsheet for SB8 in the Defense Waste Processing Facility (DWPF). These efforts pertained to the DWPF Chemical Process Cell (CPC). Separate studies were conducted for frit development and glass properties (including REDOX). The SRNL CPC effort had two primary phases divided by the decision to drop Tank 12 from the SB8 constituents. This report focuses on the second phase with SB8 compositions that do not contain the Tank 12 piece. A separate report will document the initial phase of SB8 testing that included Tank 12. The second phase of SB8 studies consisted of two sets of CPC studies. The first study involved CPC testing of an SB8 simulant for Tank 51 to support the CPC demonstration of the washed Tank 51 qualification sample in the SRNL Shielded Cells facility. SB8-Tank 51 was a high iron-low aluminum waste with fairly high mercury and moderate noble metal concentrations. Tank 51 was ultimately washed to about 1.5 M sodium which is the highest wash endpoint since SB3-Tank 51. This study included three simulations of the DWPF Sludge Receipt and Adjustment Tank (SRAT) cycle and Slurry Mix Evaporator (SME) cycle with the sludge-only flowsheet at nominal DWPF processing conditions and three different acid stoichiometries. These runs produced a set of recommendations that were used to guide the successful SRNL qualification SRAT/SME demonstration with actual Tank 51 washed waste. The second study involved five SRAT/SME runs with SB8-Tank 40 simulant. Four of the runs were designed to define the acid requirements for sludge-only processing in DWPF with respect to nitrite destruction and hydrogen generation. The fifth run was an intermediate acid stoichiometry demonstration of the coupled flowsheet for SB8. These runs produced a set of processing

  1. Osmosis : a molecular dynamics computer simulation study

    Science.gov (United States)

    Lion, Thomas

    Osmosis is a phenomenon of critical importance in a variety of processes ranging from the transport of ions across cell membranes and the regulation of blood salt levels by the kidneys to the desalination of water and the production of clean energy using potential osmotic power plants. However, despite its importance and over one hundred years of study, there is an ongoing confusion concerning the nature of the microscopic dynamics of the solvent particles in their transfer across the membrane. In this thesis the microscopic dynamical processes underlying osmotic pressure and concentration gradients are investigated using molecular dynamics (MD) simulations. I first present a new derivation for the local pressure that can be used for determining osmotic pressure gradients. Using this result, the steady-state osmotic pressure is studied in a minimal model for an osmotic system and the steady-state density gradients are explained using a simple mechanistic hopping model for the solvent particles. The simulation setup is then modified, allowing us to explore the timescales involved in the relaxation dynamics of the system in the period preceding the steady state. Further consideration is also given to the relative roles of diffusive and non-diffusive solvent transport in this period. Finally, in a novel modification to the classic osmosis experiment, the solute particles are driven out-of-equilibrium by the input of energy. The effect of this modification on the osmotic pressure and the osmotic ow is studied and we find that active solute particles can cause reverse osmosis to occur. The possibility of defining a new "osmotic effective temperature" is also considered and compared to the results of diffusive and kinetic temperatures..

  2. Molecular dynamic simulation study of molten cesium

    Directory of Open Access Journals (Sweden)

    Yeganegi Saeid

    2017-01-01

    Full Text Available Molecular dynamics simulations were performed to study thermodynamics and structural properties of expanded caesium fluid. Internal pressure, radial distribution functions (RDFs, coordination numbers and diffusion coefficients have been calculated at temperature range 700–1600 K and pressure range 100–800 bar. We used the internal pressure to predict the metal–non-metal transition occurrence region. RDFs were calculated at wide ranges of temperature and pressure. The coordination numbers decrease and positions of the first peak of RDFs slightly increase as the temperature increases and pressure decreases. The calculated self-diffusion coefficients at various temperatures and pressures show no distinct boundary between Cs metallic fluid and its expanded fluid where it continuously increases with temperature.

  3. Quench Simulation Studies: Program documentation of SPQR

    CERN Document Server

    Sonnemann, F

    2001-01-01

    Quench experiments are being performed on prototypes of the superconducting magnets and busbars to determine the adequate design and protection. Many tests can only be understood correctly with the help of quench simulations that model the thermo-hydraulic and electrodynamic processes during a quench. In some cases simulations are the only method to scale the experimental results of prototype measurements to match the situation of quenching superconducting elements in the LHC. This note introduces the theoretical quench model and the use of the simulation program SPQR (Simulation Program for Quench Research), which has been developed to compute the quench process in superconducting magnets and busbars. The model approximates the heat balance equation with the finite difference method including the temperature dependence of the material parameters. SPQR allows the simulation of longitudinal quench propagation along a superconducting cable, the transverse propagation between adjacent conductors, heat transfer i...

  4. Deep Space Storm Shelter Simulation Study

    Science.gov (United States)

    Dugan, Kathryn; Phojanamongkolkij, Nipa; Cerro, Jeffrey; Simon, Matthew

    2015-01-01

    Missions outside of Earth's magnetic field are impeded by the presence of radiation from galactic cosmic rays and solar particle events. To overcome this issue, NASA's Advanced Exploration Systems Radiation Works Storm Shelter (RadWorks) has been studying different radiation protective habitats to shield against the onset of solar particle event radiation. These habitats have the capability of protecting occupants by utilizing available materials such as food, water, brine, human waste, trash, and non-consumables to build short-term shelters. Protection comes from building a barrier with the materials that dampens the impact of the radiation on astronauts. The goal of this study is to develop a discrete event simulation, modeling a solar particle event and the building of a protective shelter. The main hallway location within a larger habitat similar to the International Space Station (ISS) is analyzed. The outputs from this model are: 1) the total area covered on the shelter by the different materials, 2) the amount of radiation the crew members receive, and 3) the amount of time for setting up the habitat during specific points in a mission given an event occurs.

  5. Conducting Simulation Studies in the R Programming Environment.

    Science.gov (United States)

    Hallgren, Kevin A

    2013-10-12

    Simulation studies allow researchers to answer specific questions about data analysis, statistical power, and best-practices for obtaining accurate results in empirical research. Despite the benefits that simulation research can provide, many researchers are unfamiliar with available tools for conducting their own simulation studies. The use of simulation studies need not be restricted to researchers with advanced skills in statistics and computer programming, and such methods can be implemented by researchers with a variety of abilities and interests. The present paper provides an introduction to methods used for running simulation studies using the R statistical programming environment and is written for individuals with minimal experience running simulation studies or using R. The paper describes the rationale and benefits of using simulations and introduces R functions relevant for many simulation studies. Three examples illustrate different applications for simulation studies, including (a) the use of simulations to answer a novel question about statistical analysis, (b) the use of simulations to estimate statistical power, and (c) the use of simulations to obtain confidence intervals of parameter estimates through bootstrapping. Results and fully annotated syntax from these examples are provided.

  6. Simulation studies for multichannel active vibration control

    Science.gov (United States)

    Prakash, Shashikala; Balasubramaniam, R.; Praseetha, K. K.

    2003-10-01

    Traditional approach to vibration control uses passive techniques, which are relatively large, costly and ineffective at low frequencies. Active Vibration Control (AVC) is used to overcome these problems & in AVC additional sources (secondary) are used to cancel vibration from primary source based on the principle of superposition theorem Since the characteristics of the vibration source and environment are time varying, the AVC system must be adaptive. Adaptive systems have the ability to track time varying disturbances and provide optimal control over a much broader range of conditions than conventional fixed control systems. In multi channel AVC vibration fields in large dimensions are controlled & is more complicated. Therefore to actively control low frequency vibrations on large structures, multi channel AVC requires a control system that uses multiple secondary sources to control the vibration field simultaneously at multiple error sensor locations. The error criterion that can be directly measured is the sum of squares of outputs of number of sensors. The adaptive algorithm is designed to minimize this & the algorithm implemented is the "Multiple error LMS algorithm." The best known applications of multiple channel FXLMS algorithm is in real time AVC and system identification. More wider applications are in the control of propeller induced noise in flight cabin interiors. In the present paper the results of simulation studies carried out in MATLAB as well as on TMS320C32 DSP processor will be brought out for a two-channel case.

  7. A Simulation Study of Paced TCP

    Science.gov (United States)

    Kulik, Joanna; Coulter, Robert; Rockwell, Dennis; Partridge, Craig

    2000-01-01

    In this paper, we study the performance of paced TCP, a modified version of TCP designed especially for high delay- bandwidth networks. In typical networks, TCP optimizes its send-rate by transmitting increasingly large bursts, or windows, of packets, one burst per round-trip time, until it reaches a maximum window-size, which corresponds to the full capacity of the network. In a network with a high delay-bandwidth product, however, Transmission Control Protocol's (TCPs) maximum window-size may be larger than the queue size of the intermediate routers, and routers will begin to drop packets as soon as the windows become too large for the router queues. The TCP sender then concludes that the bottleneck capacity of the network has been reached, and it limits its send-rate accordingly. Partridge proposed paced TCP as a means of solving the problem of queueing bottlenecks. A sender using paced TCP would release packets in multiple, small bursts during a round-trip time in which ordinary TCP would release a single, large burst of packets. This approach allows the sender to increase its send-rate to the maximum window size without encountering queueing bottlenecks. This paper describes the performance of paced TCP in a simulated network and discusses implementation details that can affect the performance of paced TCP.

  8. Simulation Study (SimStudy): A Simulation Tool for Engineers and Mission Planners

    Science.gov (United States)

    2013-09-01

    and build additional terrain databases . The SimStudy continues to be updated to mimic the ever-improving capabilities and demands of simulation...April 2009. 9. Stoliker, F.N., “ AGARD Flight Test Techniques Series, Volume 14: Introduction to Flight Test Engineering,” North Atlantic Treaty...Organization Advisory Group for Aerospace Research and Development, AGARD -AG_300 Vol. 14, Neuilly-Sur-Seine, France, September 1995. 14 LIST OF

  9. Development of a Cardiovascular Simulator for Studying Pulse Diagnosis Mechanisms

    Directory of Open Access Journals (Sweden)

    Min Jang

    2017-01-01

    Full Text Available This research was undertaken to develop a cardiovascular simulator for use in the study of pulse diagnosis. The physical (i.e., pulse wave transmission and reflection and physiological (i.e., systolic and diastolic pressure, pulse pressure, and mean pressure characteristics of the radial pulse wave were reproduced by our simulator. The simulator consisted of an arterial component and a pulse-generating component. Computer simulation was used to simplify the arterial component while maintaining the elastic modulus and artery size. To improve the reflected wave characteristics, a palmar arch was incorporated within the simulator. The simulated radial pulse showed good agreement with clinical data.

  10. Conducting Simulation Studies in the R Programming Environment

    Directory of Open Access Journals (Sweden)

    Kevin A. Hallgren

    2013-10-01

    Full Text Available Simulation studies allow researchers to answer specific questions about data analysis, statistical power, and best-practices for obtainingaccurate results in empirical research. Despite the benefits that simulation research can provide, many researchers are unfamiliar with available tools for conducting their own simulation studies. The use of simulation studies need not be restricted toresearchers with advanced skills in statistics and computer programming, and such methods can be implemented by researchers with a variety of abilities and interests. The present paper provides an introduction to methods used for running simulationstudies using the R statistical programming environment and is written for individuals with minimal experience running simulation studies or using R. The paper describes the rationale and benefits of using simulations and introduces R functions relevant for many simulation studies. Three examples illustrate different applications for simulation studies, including (a the use of simulations to answer a novel question about statistical analysis, (b the use of simulations to estimate statistical power, and (c the use of simulations to obtain confidence intervals of parameter estimates throughbootstrapping. Results and fully annotated syntax from these examples are provided.

  11. A simulation tool for brassiness studies.

    Science.gov (United States)

    Gilbert, Joël; Menguy, Ludovic; Campbell, Murray

    2008-04-01

    A frequency-domain numerical model of brass instrument sound production is proposed as a tool to predict their brassiness, defined as the rate of spectral enrichment with increasing dynamic level. It is based on generalized Burger's equations dedicated to weakly nonlinear wave propagation in nonuniform ducts, and is an extension of previous work by Menguy and Gilbert [Acta Acustica 86, 798-810 (2000)], initially limited to short cylindrical tubes. The relevance of the present tool is evaluated by carrying out simulations over distances longer than typical shock formation distances, and by doing preliminary simulations of periodic regimes in a typical brass trombone bore geometry.

  12. Studying Scientific Discovery by Computer Simulation.

    Science.gov (United States)

    1983-03-30

    scientific laws that were induced from data before any theory was available to discover the regularities. To the previous examples, we could add Gregor ...discoveries (excluding those of Mendel and Mendeleev, which we have not simulated) could have been made. The Role of Theory in Law Induction BACON’s

  13. Computer Simulation Studies of Trishomocubane Heptapeptide of ...

    African Journals Online (AJOL)

    As part of an extension on the cage peptide chemistry, the present work involves an assessment of the conformational profile of trishomocubane heptapeptide of the type Ac-Ala3-Tris-Ala3-NHMe using molecular dynamics (MD) simulations. All MD protocols were explored within the framework of a molecular mechanics ...

  14. Partnering to Establish and Study Simulation in International Nursing Education.

    Science.gov (United States)

    Garner, Shelby L; Killingsworth, Erin; Raj, Leena

    The purpose of this article was to describe an international partnership to establish and study simulation in India. A pilot study was performed to determine interrater reliability among faculty new to simulation when evaluating nursing student competency performance. Interrater reliability was below the ideal agreement level. Findings in this study underscore the need to obtain baseline interrater reliability data before integrating competency evaluation into a simulation program.

  15. Unit Under Test Simulator Feasibility Study.

    Science.gov (United States)

    1980-06-01

    Source 0 Nonlinear Elements Nonlinear Voltage-Controlled Current Source Diode Bipolar Junction Transistor ( BJT ) Junction Field-Effect Transistor (JFET...circuit element component levels, such as resistor, capacitor, and transistor . As such, it can provide very accurate simulation with regard to signal...Insulated- Gate Field-Effect Transistor (MOSFET) Each model in turn contains many parameters which are used to reflect the individual device

  16. Geothermal systems simulation: A case study

    OpenAIRE

    Guerrero-Martinez, Fernando J.; Verma, Surendra P.; Younger, Paul; Paul, Manosh C.

    2015-01-01

    Geothermal reservoir simulation is a key step for developing sustainable and efficient strategies for the exploitation of geothermal resources. It is applied in the assessment of several areas of reservoir engineering, such as reservoir performance and re-injection programs, pressure decline in depletion, phase transition conditions, and natural evolution of hydrothermal convection systems. Fluid flow and heat transfer in rock masses, fluid-rock chemical interaction and rock mass deformation ...

  17. Simulation

    CERN Document Server

    Ross, Sheldon

    2006-01-01

    Ross's Simulation, Fourth Edition introduces aspiring and practicing actuaries, engineers, computer scientists and others to the practical aspects of constructing computerized simulation studies to analyze and interpret real phenomena. Readers learn to apply results of these analyses to problems in a wide variety of fields to obtain effective, accurate solutions and make predictions about future outcomes. This text explains how a computer can be used to generate random numbers, and how to use these random numbers to generate the behavior of a stochastic model over time. It presents the statist

  18. Laparoscopic skills acquisition: a study of simulation and traditional training.

    Science.gov (United States)

    Marlow, Nicholas; Altree, Meryl; Babidge, Wendy; Field, John; Hewett, Peter; Maddern, Guy J

    2014-12-01

    Training in basic laparoscopic skills can be undertaken using traditional methods, where trainees are educated by experienced surgeons through a process of graduated responsibility or by simulation-based training. This study aimed to assess whether simulation trained individuals reach the same level of proficiency in basic laparoscopic skills as traditional trained participants when assessed in a simulated environment. A prospective study was undertaken. Participants were allocated to one of two cohorts according to surgical experience. Participants from the inexperienced cohort were randomized to receive training in basic laparoscopic skills on either a box trainer or a virtual reality simulator. They were then assessed on the simulator on which they did not receive training. Participants from the experienced cohort, considered to have received traditional training in basic laparoscopic skills, did not receive simulation training and were randomized to either the box trainer or virtual reality simulator for skills assessment. The assessment scores from different cohorts on either simulator were then compared. A total of 138 participants completed the assessment session, 101 in the inexperienced simulation-trained cohort and 37 on the experienced traditionally trained cohort. There was no statistically significant difference between the training outcomes of simulation and traditionally trained participants, irrespective of the simulator type used. The results demonstrated that participants trained on either a box trainer or virtual reality simulator achieved a level of basic laparoscopic skills assessed in a simulated environment that was not significantly different from participants who had been traditionally trained in basic laparoscopic skills. © 2013 Royal Australasian College of Surgeons.

  19. Simulations

    CERN Document Server

    Ngada, Narcisse

    2015-06-15

    The complexity and cost of building and running high-power electrical systems make the use of simulations unavoidable. The simulations available today provide great understanding about how systems really operate. This paper helps the reader to gain an insight into simulation in the field of power converters for particle accelerators. Starting with the definition and basic principles of simulation, two simulation types, as well as their leading tools, are presented: analog and numerical simulations. Some practical applications of each simulation type are also considered. The final conclusion then summarizes the main important items to keep in mind before opting for a simulation tool or before performing a simulation.

  20. A simulation based engineering method to support HAZOP studies

    DEFF Research Database (Denmark)

    Enemark-Rasmussen, Rasmus; Cameron, David; Angelo, Per Bagge

    2012-01-01

    HAZOP is the most commonly used process hazard analysis tool in industry, a systematic yet tedious and time consuming method. The aim of this study is to explore the feasibility of process dynamic simulations to facilitate the HAZOP studies. We propose a simulation-based methodology to complement...... the conventional HAZOP procedure. The method systematically generates failure scenarios by considering process equipment deviations with pre-defined failure modes. The effect of failure scenarios is then evaluated using dynamic simulations -in this study the K-Spice® software used. The consequences of each failure...... model as case study....

  1. Nuclear wasteform materials: Atomistic simulation case studies

    Energy Technology Data Exchange (ETDEWEB)

    Chroneos, A., E-mail: alex.chroneos@open.ac.uk [Materials Engineering, The Open University, Milton Keynes MK7 6AA (United Kingdom); Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Institute of Materials Science, NCSR Demokritos, GR-15310 Athens (Greece); Rushton, M.J.D. [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Jiang, C. [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Tsoukalas, L.H. [Department of Nuclear Engineering, Purdue University, West Lafayette, IN 47907 (United States)

    2013-10-15

    Ever increasing global energy demand combined with a requirement to reduce CO{sub 2} emissions has rekindled an interest in nuclear power generation. In order that nuclear energy remains publicly acceptable and therefore a sustainable source of power it is important that nuclear waste is dealt with in a responsible manner. To achieve this, improved materials for the long-term immobilisation of waste should be developed. The extreme conditions experienced by nuclear wasteforms necessitate the detailed understanding of their properties and the mechanisms acting within them at the atomic scale. This latter issue is the focus of the present review. Atomic scale simulation techniques can accelerate the development of new materials for nuclear wasteform applications and provide detailed information on their physical properties that cannot be easily accessed by experiment. The present article introduces examples of how atomic scale, computational modelling techniques have led to an improved understanding of current nuclear wasteform materials and also suggest how they may be used in the development of new wasteforms.

  2. Disruption Studies and Simulations in Ignitor

    Science.gov (United States)

    Ramogida, G.; Villone, F.; Rubinacci, G.; Coppi, B.

    2014-10-01

    The prediction of plasma disruption features and evaluation of the associated EM loads played an important role in the development of Ignitor. The kind and number of expected plasma disruptions drove the development of the plasma scenarios and the design of in-vessel components, as these events produced by far the largest EM loads the components must withstand. A strong integration of physics and engineering expertise was required to estimate the range of expected variation, based on the experimental data from existing machines, of the main parameters of the disruptions: thermal and current quench times, evolution of the plasma current, li, safety factor limits, halo current fraction and width, and radiated heat fraction. The MAXFEA axisymmetric 2D MHD code was used to evaluate the effects on the induced currents and EM loads caused by variation of the disruption parameters. Further, the detailed evolution of the plasma was simulated using the CarMa0NL code, which is able to self-consistently couple a nonlinear axisymmetric plasma evolution with volumetric 3D conductors. This allows the evaluation of the effects of the non-axisymmetric components of the machine such as the plasma chamber ports. US DOE partily sponsord.

  3. Simulation Studies for the evaluation of health information technologies:

    DEFF Research Database (Denmark)

    Ammenwerth, Elske; Hackl, Werner O; Binzer, Kristine

    2012-01-01

    system on the appropriateness of prescriptions and drugrelated activities, including laboratory test ordering or medication changes. This article presents the results of a controlled simulation study with 50 simulation runs, including ten doctors and fi ve simulation patients, and discusses experiences...... and lessons learnt while conducting the study. Although the new electronic medication management system showed tendencies to improve medication safety when compared with the standard system, this tendency was not significant. Altogether, fi ve distinct situations were identifi ed where the new medication...... management system did help to improve medication safety. This simulation study provided a good compromise between internal validity and external validity. However, several challenges need to be addressed when undertaking simulation evaluations including: preparation of adequate test cases; training...

  4. Case studies of simulation models of recreation use

    Science.gov (United States)

    David N. Cole

    2005-01-01

    Computer simulation models can be usefully applied to many different outdoor recreation situations. Model outputs can also be used for a wide variety of planning and management purposes. The intent of this chapter is to use a collection of 12 case studies to illustrate how simulation models have been used in a wide range of recreation situations and for diverse...

  5. Simulation: etude de cas et jeu de role (Simulation: Case Study and Role-Playing).

    Science.gov (United States)

    Jelila, Najib; And Others

    1985-01-01

    Outlined is the use of two kinds of simulation (case study and role playing) for non-native teachers of French studying in France to develop as part of their foreign-study program as if it were to be used in their own country. (MSE)

  6. Aircraft Simulator Data Requirements Study. Volume II

    Science.gov (United States)

    1977-01-01

    planned, to solicit suggestions relative to the study approach, and to again point out the importance of cooperacion . Representatives from the Aeronautical...be a trn-service document. The decision was reached that this study was to address fixed wing, horizontal takeoff, turbojet, turbofan, or turboprop

  7. Simulation Studies for the evaluation of health information technologies:

    DEFF Research Database (Denmark)

    Ammenwerth, Elske; Hackl, Werner O; Binzer, Kristine

    2012-01-01

    system on the appropriateness of prescriptions and drugrelated activities, including laboratory test ordering or medication changes. This article presents the results of a controlled simulation study with 50 simulation runs, including ten doctors and fi ve simulation patients, and discusses experiences......It is essential for new health information technologies (IT) to undergo rigorous evaluations to ensure they are effective and safe for use in real-world situations. However, evaluation of new health IT is challenging, as field studies are often not feasible when the technology being evaluated...

  8. Performing simulation study on drill string mechanics, Torque and Drag.

    OpenAIRE

    Chakraborty, Tanmoy

    2012-01-01

    Master's thesis in Petroleum engineering In this thesis work, a simulation and monitoring study was carried based on operational data obtained from two wells. These are South Sangu-4 and Sangu-11, which are situated in block 16. From the study it was found out that: Comparing the simulation data and real time data, the tripping in and tripping out coefficient of friction were back calculated .The coefficient of frictions derived from Sangu-4 were used for planning of drilling in Sa...

  9. Theoretical and simulation studies of seeding methods

    Energy Technology Data Exchange (ETDEWEB)

    Pellegrini, Claudio [Univ. of California, Los Angeles, CA (United States)

    2017-12-11

    We report the theoretical and experimental studies done with the support of DOE-Grant DE-SC0009983 to increase an X-ray FEL peak power from the present level of 20 to 40 GW to one or more TW by seeding, undulator tapering and using the new concept of the Double Bunch FEL.

  10. Simulation and Study of High Workload Operations

    Science.gov (United States)

    1974-04-25

    CHASE WILKINSON MACNAMARA DISCUSSION To which category of pilots to the figures on flying hours refer? These figures were obtained fron the air...studies on cholesterol levels in the Johns Hopkins medical students: The effect of stress at examinations. J. Chronic Pis., 8:661, 1958. 4. Friedman, M

  11. Study of Navy Recruiting Simulation Tool

    Science.gov (United States)

    2010-03-01

    Such memory aids are useful in areas of study, such as music, science, and math , but not in every learning situation. An example of this would be...interface refers to the voice and pre- set responses to the applicant, the applicant’s responses, the PSS tutor , and the final score card. Overall, 26.5...instructors and peers ; and higher quality mentoring experiences. The Stanford research strongly suggests that linking self-paced material to live e

  12. Simulation Studies for the evaluation of health information technologies:

    DEFF Research Database (Denmark)

    Ammenwerth, Elske; Hackl, Werner O; Binzer, Kristine

    2012-01-01

    It is essential for new health information technologies (IT) to undergo rigorous evaluations to ensure they are effective and safe for use in real-world situations. However, evaluation of new health IT is challenging, as field studies are often not feasible when the technology being evaluated...... of participants before using unfamiliar applications; consideration of time, effort and costs of conducting the simulation; technical maturity of the evaluated system; and allowing adequate preparation of simulation scenarios and simulation setting. Simulation studies are an interesting but time......-consuming approach, which can be used to evaluate newly developed health IT systems, particularly those systems that are not yet suffi ciently mature to undergo field evaluation studies....

  13. Simulation studies for the evaluation of health information technologies

    DEFF Research Database (Denmark)

    Ammenwerth, Elske; Hackl, Werner; Binzer, Kristine

    2012-01-01

    It is essential for new health information technologies (IT) to undergo rigorous evaluations to ensure they are effective and safe for use in real-world situations. However, evaluation of new health IT is challenging, as field studies are often not feasible when the technology being evaluated...... of participants before using unfamiliar applications; consideration of time, effort and costs of conducting the simulation; technical maturity of the evaluated system; and allowing adequate preparation of simulation scenarios and simulation setting. Simulation studies are an interesting but time......-consuming approach, which can be used to evaluate newly developed health IT systems, particularly those systems that are not yet sufficiently mature to undergo field evaluation studies....

  14. Simulation Use in Paramedic Education Research (SUPER): A Descriptive Study

    Science.gov (United States)

    McKenna, Kim D.; Carhart, Elliot; Bercher, Daniel; Spain, Andrew; Todaro, John; Freel, Joann

    2015-01-01

    Abstract Objectives. The purpose of this research was to characterize the use of simulation in initial paramedic education programs in order assist stakeholders’ efforts to target educational initiatives and resources. This group sought to provide a snapshot of what simulation resources programs have or have access to and how they are used; faculty perceptions about simulation; whether program characteristics, resources, or faculty training influence simulation use; and if simulation resources are uniform for patients of all ages. Methods. This was a cross-sectional census survey of paramedic programs that were accredited or had a Letter of Review from the Committee on Accreditation of Educational Programs for the EMS Professions at the time of the study. The data were analyzed using descriptive statistics and chi-square analyses. Results. Of the 638 surveys sent, 389 valid responses (61%) were analyzed. Paramedic programs reported they have or have access to a wide range of simulation resources (task trainers [100%], simple manikins [100%], intermediate manikins [99%], advanced/fully programmable manikins [91%], live simulated patients [83%], computer-based [71%], and virtual reality [19%]); however, they do not consistently use them, particularly advanced (71%), live simulated patients (66%), computer-based (games, scenarios) (31%), and virtual reality (4%). Simulation equipment (of any type) reportedly sits idle and unused in (31%) of programs. Lack of training was cited as the most common reason. Personnel support specific to simulation was available in 44% of programs. Programs reported using simulation to replace skills more frequently than to replace field or clinical hours. Simulation goals included assessment, critical thinking, and problem-solving most frequently, and patient and crew safety least often. Programs using advanced manikins report manufacturers as their primary means of training (87%) and that 19% of faculty had no training specific to

  15. Software for Brain Network Simulations: A Comparative Study

    Science.gov (United States)

    Tikidji-Hamburyan, Ruben A.; Narayana, Vikram; Bozkus, Zeki; El-Ghazawi, Tarek A.

    2017-01-01

    Numerical simulations of brain networks are a critical part of our efforts in understanding brain functions under pathological and normal conditions. For several decades, the community has developed many software packages and simulators to accelerate research in computational neuroscience. In this article, we select the three most popular simulators, as determined by the number of models in the ModelDB database, such as NEURON, GENESIS, and BRIAN, and perform an independent evaluation of these simulators. In addition, we study NEST, one of the lead simulators of the Human Brain Project. First, we study them based on one of the most important characteristics, the range of supported models. Our investigation reveals that brain network simulators may be biased toward supporting a specific set of models. However, all simulators tend to expand the supported range of models by providing a universal environment for the computational study of individual neurons and brain networks. Next, our investigations on the characteristics of computational architecture and efficiency indicate that all simulators compile the most computationally intensive procedures into binary code, with the aim of maximizing their computational performance. However, not all simulators provide the simplest method for module development and/or guarantee efficient binary code. Third, a study of their amenability for high-performance computing reveals that NEST can almost transparently map an existing model on a cluster or multicore computer, while NEURON requires code modification if the model developed for a single computer has to be mapped on a computational cluster. Interestingly, parallelization is the weakest characteristic of BRIAN, which provides no support for cluster computations and limited support for multicore computers. Fourth, we identify the level of user support and frequency of usage for all simulators. Finally, we carry out an evaluation using two case studies: a large network with

  16. ATLAS Tracking Detector Upgrade studies using the Fast Simulation Engine

    CERN Document Server

    Calace, Noemi; The ATLAS collaboration

    2015-01-01

    The successful physics program Run-1 of the LHC has put a strong emphasis on design studies for future upgrades of the existing LHC detectors. In ATLAS, testing alternative layouts through the full simulation and reconstruction chain is a work-intensive program, which can only be carried out for a few concept layouts. To facilitate layout prototyping, we have established a novel technique based on the ATLAS reconstruction geometry and a fast simulation engine that allows fast layout iterations and a realistic but fast Monte Carlo simulation. This approach is extended by a fast digitisation and reconstruction module.

  17. MODELING SIMULATION AND PERFORMANCE STUDY OF GRIDCONNECTED PHOTOVOLTAIC ENERGY SYSTEM

    OpenAIRE

    Nagendra K; Karthik J; Keerthi Rao C; Kumar Raja Pemmadi

    2017-01-01

    This paper presents Modeling Simulation of grid connected Photovoltaic Energy System and performance study using MATLAB/Simulink. The Photovoltaic energy system is considered in three main parts PV Model, Power conditioning System and Grid interface. The Photovoltaic Model is inter-connected with grid through full scale power electronic devices. The simulation is conducted on the PV energy system at normal temperature and at constant load by using MATLAB.

  18. FLUKA Simulations for SEE Studies of Critical LHC Underground Areas

    CERN Document Server

    Roed, K; Brugger, M; Spiezia, G; Losito, R; Boccone, V; Ferrari, A; Versaci, R; Lebbos, E; Mereghetti, A

    2011-01-01

    FLUKA Monte Carlo simulations have been performed to identify particle energy spectra and fluences relevant for evaluating the risk of single event effects in electronics installed in critical LHC underground areas. Since these simulations are associated with significant uncertainties, the results will compared with an online monitoring system installed to evaluate radiation levels at the location of the electronics. This comparison approach have been benchmarked in a mixed field reference facility and for a preliminary LHC monitoring case study.

  19. Virtual reality simulation training of mastoidectomy - studies on novice performance.

    Science.gov (United States)

    Andersen, Steven Arild Wuyts

    2016-08-01

    Virtual reality (VR) simulation-based training is increasingly used in surgical technical skills training including in temporal bone surgery. The potential of VR simulation in enabling high-quality surgical training is great and VR simulation allows high-stakes and complex procedures such as mastoidectomy to be trained repeatedly, independent of patients and surgical tutors, outside traditional learning environments such as the OR or the temporal bone lab, and with fewer of the constraints of traditional training. This thesis aims to increase the evidence-base of VR simulation training of mastoidectomy and, by studying the final-product performances of novices, investigates the transfer of skills to the current gold-standard training modality of cadaveric dissection, the effect of different practice conditions and simulator-integrated tutoring on performance and retention of skills, and the role of directed, self-regulated learning. Technical skills in mastoidectomy were transferable from the VR simulation environment to cadaveric dissection with significant improvement in performance after directed, self-regulated training in the VR temporal bone simulator. Distributed practice led to a better learning outcome and more consolidated skills than massed practice and also resulted in a more consistent performance after three months of non-practice. Simulator-integrated tutoring accelerated the initial learning curve but also caused over-reliance on tutoring, which resulted in a drop in performance when the simulator-integrated tutor-function was discontinued. The learning curves were highly individual but often plateaued early and at an inadequate level, which related to issues concerning both the procedure and the VR simulator, over-reliance on the tutor function and poor self-assessment skills. Future simulator-integrated automated assessment could potentially resolve some of these issues and provide trainees with both feedback during the procedure and immediate

  20. Effect of simulator motion cuing on steering control performance : Driving simulator study

    NARCIS (Netherlands)

    Feenstra, P.J.; Horst, A.R.A. van der; Grácio, B.J.C.; Wentink, M.

    2010-01-01

    The goal of the present study was to explore how simulator motion cuing affects the driver's control performance of a car. Steering behavior was used as a measure of control performance. The experimental task was a slalom maneuver in which the velocity of the car was limited to 70 km/h. Subjective

  1. Study on the CFD simulation of refrigerated container

    Science.gov (United States)

    Arif Budiyanto, Muhammad; Shinoda, Takeshi; Nasruddin

    2017-10-01

    The objective this study is to performed Computational Fluid Dynamic (CFD) simulation of refrigerated container in the container port. Refrigerated container is a thermal cargo container constructed from an insulation wall to carry kind of perishable goods. CFD simulation was carried out use cross sectional of container walls to predict surface temperatures of refrigerated container and to estimate its cooling load. The simulation model is based on the solution of the partial differential equations governing the fluid flow and heat transfer processes. The physical model of heat-transfer processes considered in this simulation are consist of solar radiation from the sun, heat conduction on the container walls, heat convection on the container surfaces and thermal radiation among the solid surfaces. The validation of simulation model was assessed uses surface temperatures at center points on each container walls obtained from the measurement experimentation in the previous study. The results shows the surface temperatures of simulation model has good agreement with the measurement data on all container walls.

  2. Human factors in resuscitation: Lessons learned from simulator studies

    Directory of Open Access Journals (Sweden)

    Hunziker S

    2010-01-01

    Full Text Available Medical algorithms, technical skills, and repeated training are the classical cornerstones for successful cardiopulmonary resuscitation (CPR. Increasing evidence suggests that human factors, including team interaction, communication, and leadership, also influence the performance of CPR. Guidelines, however, do not yet include these human factors, partly because of the difficulties of their measurement in real-life cardiac arrest. Recently, clinical studies of cardiac arrest scenarios with high-fidelity video-assisted simulations have provided opportunities to better delineate the influence of human factors on resuscitation team performance. This review focuses on evidence from simulator studies that focus on human factors and their influence on the performance of resuscitation teams. Similar to studies in real patients, simulated cardiac arrest scenarios revealed many unnecessary interruptions of CPR as well as significant delays in defibrillation. These studies also showed that human factors play a major role in these shortcomings and that the medical performance depends on the quality of leadership and team-structuring. Moreover, simulated video-taped medical emergencies revealed that a substantial part of information transfer during communication is erroneous. Understanding the impact of human factors on the performance of a complex medical intervention like resuscitation requires detailed, second-by-second, analysis of factors involving the patient, resuscitative equipment such as the defibrillator, and all team members. Thus, high-fidelity simulator studies provide an important research method in this challenging field.

  3. PELS (Planetary Environmental Liquid Simulator): a new type of simulation facility to study extraterrestrial aqueous environments.

    Science.gov (United States)

    Martin, Derek; Cockell, Charles S

    2015-02-01

    Investigations of other planetary bodies, including Mars and icy moons such as Enceladus and Europa, show that they may have hosted aqueous environments in the past and may do so even today. Therefore, a major challenge in astrobiology is to build facilities that will allow us to study the geochemistry and habitability of these extraterrestrial environments. Here, we describe a simulation facility (PELS: Planetary Environmental Liquid Simulator) with the capability for liquid input and output that allows for the study of such environments. The facility, containing six separate sample vessels, allows for statistical replication of samples. Control of pressure, gas composition, UV irradiation conditions, and temperature allows for the precise replication of aqueous conditions, including subzero brines under martian atmospheric conditions. A sample acquisition system allows for the collection of both liquid and solid samples from within the chamber without breaking the atmospheric conditions, enabling detailed studies of the geochemical evolution and habitability of past and present extraterrestrial environments. The facility we describe represents a new frontier in planetary simulation-continuous flow-through simulation of extraterrestrial aqueous environments.

  4. Simulation Studies for the evaluation of health information technologies:

    DEFF Research Database (Denmark)

    Ammenwerth, Elske; Hackl, Werner O; Binzer, Kristine

    2012-01-01

    It is essential for new health information technologies (IT) to undergo rigorous evaluations to ensure they are effective and safe for use in real-world situations. However, evaluation of new health IT is challenging, as field studies are often not feasible when the technology being evaluated...... is not sufficiently mature. Laboratory-based evaluations have also been shown to have insufficient external validity. Simulation studies seem to be a way to bridge this gap. The aim of this study was to evaluate, using a simulation methodology, the impact of a new prototype of an electronic medication management...

  5. Framework for Architecture Trade Study Using MBSE and Performance Simulation

    Science.gov (United States)

    Ryan, Jessica; Sarkani, Shahram; Mazzuchim, Thomas

    2012-01-01

    Increasing complexity in modern systems as well as cost and schedule constraints require a new paradigm of system engineering to fulfill stakeholder needs. Challenges facing efficient trade studies include poor tool interoperability, lack of simulation coordination (design parameters) and requirements flowdown. A recent trend toward Model Based System Engineering (MBSE) includes flexible architecture definition, program documentation, requirements traceability and system engineering reuse. As a new domain MBSE still lacks governing standards and commonly accepted frameworks. This paper proposes a framework for efficient architecture definition using MBSE in conjunction with Domain Specific simulation to evaluate trade studies. A general framework is provided followed with a specific example including a method for designing a trade study, defining candidate architectures, planning simulations to fulfill requirements and finally a weighted decision analysis to optimize system objectives.

  6. Validation study of the mine fire simulation model

    Energy Technology Data Exchange (ETDEWEB)

    Wala, A.M.; Dziurzynski, W.; Tracz, J.; Wooton, D.

    1995-12-31

    The purpose of this paper is to present validation studies of the mine-fire simulator using data gathered from an actual mine fire which occurred in November 1991 at the Pattiki Mine. This study evaluates the suitability of the computer software package for modeling underground fires. The paper also discusses the importance of the on-line monitoring system for the validation process.

  7. Study on corrosion simulation device for marine structural steel

    Indian Academy of Sciences (India)

    A corrosion simulation device was studied using offshore long scale hanging specimens. An Ni–Cu–P steel specimen was studied by analysing its corrosion products and corrosion types. The appearance of the samples and the surface of the metallic substrate after the removal of the rust layer produced by these two ...

  8. Study on corrosion simulation device for marine structural steel

    Indian Academy of Sciences (India)

    Unknown

    †Also at Graduate School of the Chinese Academy of Sciences, Beijing 100039, China. MS received 9 January 2003. Abstract. A corrosion simulation device was studied using offshore long scale hanging specimens. An Ni–. Cu–P steel specimen was studied by analysing its corrosion products and corrosion types.

  9. Computer Simulation in the Teaching of Translation and International Studies.

    Science.gov (United States)

    Brecht, Richard D.; And Others

    1984-01-01

    Describes the National Simulation in International Studies and Translation Program which links international studies and foreign languages programs at a number of universities. This program provides a natural context for the exercise of translation for the language student and an authenticity of experience for students of international politics.…

  10. Simulation Studies for the evaluation of health information technologies:

    DEFF Research Database (Denmark)

    Ammenwerth, Elske; Hackl, Werner O; Binzer, Kristine

    2012-01-01

    management system did help to improve medication safety. This simulation study provided a good compromise between internal validity and external validity. However, several challenges need to be addressed when undertaking simulation evaluations including: preparation of adequate test cases; training......It is essential for new health information technologies (IT) to undergo rigorous evaluations to ensure they are effective and safe for use in real-world situations. However, evaluation of new health IT is challenging, as field studies are often not feasible when the technology being evaluated...

  11. Dark Energy Studies with LSST Image Simulations, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, John Russell [Purdue Univ., West Lafayette, IN (United States)

    2016-07-26

    This grant funded the development and dissemination of the Photon Simulator (PhoSim) for the purpose of studying dark energy at high precision with the upcoming Large Synoptic Survey Telescope (LSST) astronomical survey. The work was in collaboration with the LSST Dark Energy Science Collaboration (DESC). Several detailed physics improvements were made in the optics, atmosphere, and sensor, a number of validation studies were performed, and a significant number of usability features were implemented. Future work in DESC will use PhoSim as the image simulation tool for data challenges used by the analysis groups.

  12. Computer Simulation for Pain Management Education: A Pilot Study.

    Science.gov (United States)

    Allred, Kelly; Gerardi, Nicole

    2017-10-01

    Effective pain management is an elusive concept in acute care. Inadequate knowledge has been identified as a barrier to providing optimal pain management. This study aimed to determine student perceptions of an interactive computer simulation as a potential method for learning pain management, as a motivator to read and learn more about pain management, preference over traditional lecture, and its potential to change nursing practice. A post-computer simulation survey with a mixed-methods descriptive design was used in this study. A college of nursing in a large metropolitan university in the Southeast United States. A convenience sample of 30 nursing students in a Bachelor of Science nursing program. An interactive computer simulation was developed as a potential alternative method of teaching pain management to nursing students. Increases in educational gain as well as its potential to change practice were explored. Each participant was asked to complete a survey consisting of 10 standard 5-point Likert scale items and 5 open-ended questions. The survey was used to evaluate the students' perception of the simulation, specifically related to educational benefit, preference compared with traditional teaching methods, and perceived potential to change nursing practice. Data provided descriptive statistics for initial evaluation of the computer simulation. The responses on the survey suggest nursing students perceive the computer simulation to be entertaining, fun, educational, occasionally preferred over regular lecture, and with potential to change practice. Preliminary data support the use of computer simulation in educating nursing students about pain management. Copyright © 2017 American Society for Pain Management Nursing. Published by Elsevier Inc. All rights reserved.

  13. Simulation Studies of the Helium and Lead Observatory (HALO)

    Science.gov (United States)

    Sanford, Nikki; Scholberg, Kate

    2012-10-01

    Simulation studies for were conducted for the Helium and Lead Observatory (HALO), the supernova neutrino detector at SNOLAB, Sudbury, Ontario. HALO consists of 79 tons of lead, with 128 ^3He counters which detect the scattered lead neutrons resulting from incoming neutrinos. Improvements were made to the Geant4 Monte Carlo simulation's geometry by the addition of water boxes and plastic baseboards, which serve to reflect scattered neutrons back towards counters, and shield against outside neutrons and gammas. Several box designs were created, and the resulting event detection efficiencies and labeling of 1n and 2n events were studied. It was found that these additions cause a 2% efficiency increase, a slight improvement of correctly labeled events, and are a significant improvement to the HALO simulation.

  14. Observer study to evaluate the simulation of mammographic calcification clusters

    Science.gov (United States)

    Sousa, Maria A. Z.; Marcomini, Karem D.; Bakic, Predrag R.; Maidment, Andrew D. A.; Schiabel, Homero

    2016-03-01

    Numerous breast phantoms have been developed to be as realistic as possible to ensure the accuracy of image quality analysis, covering a greater range of applications. In this study, we simulated three different densities of the breast parenchyma using paraffin gel, acrylic plates and PVC films. Hydroxyapatite was used to simulate calcification clusters. From the images acquired with a GE Senographe DR 2000D mammography system, we selected 68 regions of interest (ROIs) with and 68 without a simulated calcification cluster. To validate the phantom simulation, we selected 136 ROIs from the University of South Florida's Digital Database for Screening Mammography (DDSM). Seven trained observers performed two observer experiments by using a high-resolution monitor Barco mod. E-3620. In the first experiment, the observers had to distinguish between real or phantom ROIs (with and without calcification). In the second one, the observers had to indicate the ROI with calcifications between a pair of ROIs. Results from our study show that the hydroxyapatite calcifications had poor contrast in the simulated breast parenchyma, thus observers had more difficulty in identifying the presence of calcification clusters in phantom images. Preliminary analysis of the power spectrum was conducted to investigate the radiographic density and the contrast thresholds for calcification detection. The values obtained for the power spectrum exponent (β) were comparable with those found in the literature.

  15. The simulation study on optical target laser active detection performance

    Science.gov (United States)

    Li, Ying-chun; Hou, Zhao-fei; Fan, Youchen

    2014-12-01

    According to the working principle of laser active detection system, the paper establishes the optical target laser active detection simulation system, carry out the simulation study on the detection process and detection performance of the system. For instance, the performance model such as the laser emitting, the laser propagation in the atmosphere, the reflection of optical target, the receiver detection system, the signal processing and recognition. We focus on the analysis and modeling the relationship between the laser emitting angle and defocus amount and "cat eye" effect echo laser in the reflection of optical target. Further, in the paper some performance index such as operating range, SNR and the probability of the system have been simulated. The parameters including laser emitting parameters, the reflection of the optical target and the laser propagation in the atmosphere which make a great influence on the performance of the optical target laser active detection system. Finally, using the object-oriented software design methods, the laser active detection system with the opening type, complete function and operating platform, realizes the process simulation that the detection system detect and recognize the optical target, complete the performance simulation of each subsystem, and generate the data report and the graph. It can make the laser active detection system performance models more intuitive because of the visible simulation process. The simulation data obtained from the system provide a reference to adjust the structure of the system parameters. And it provides theoretical and technical support for the top level design of the optical target laser active detection system and performance index optimization.

  16. improving clinical practice through simulation: a case study of ...

    African Journals Online (AJOL)

    PROF. BARTH EKWEME

    A survey design was used for the study. ... completed the survey, indicating their confidence in various skills necessary for patient examination, both before and .... Research questions. • How do nursing students perceive the value of using clinical simulation in their learning? • Do nursing students perceive that they are able.

  17. School Leadership and Administration: Important Concepts, Case Studies and Simulations

    Science.gov (United States)

    Gorton, Richard; Alston, Judy; Snowden, Petra

    2006-01-01

    This text helps prospective and experienced principals, administrators, and supervisors increase their knowledge and skills through concepts, case-studies, and simulations. This book contains the following two parts and fifteen chapters. Part I presents important theoretical concepts and research findings that can improve educators'…

  18. Improving clinical practice through simulation: A case study of ...

    African Journals Online (AJOL)

    Acquisition of knowledge and skills by nursing students before real-life practice is a familiar nursing education challenge. The use of clinical simulation in nursing education provides many opportunities for students to learn and apply theoretical principles of nursing care in a safe environment. The purpose of this study was ...

  19. Comparative Study of the Simulated and Calculation Gantry Angle ...

    African Journals Online (AJOL)

    This prospec-tive study was conducted at the National Center for Radiotherapy and Nuclear Medicine, Accra, Ghana between June and October, 2012 with a sample size of 50 breast cancer patients. The simu-lator method was compared with the calculated method to assess if the two methods can be used interchangeably ...

  20. A study of pleasantness and annoyance in simulated soundscapes

    DEFF Research Database (Denmark)

    Alvarez, Jorge; Konstantinos, Angelakis; Rindel, Jens Holger

    2006-01-01

    An experimental study has been conducted in the Acoustic Technology Department of the Technical University of Denmark. Audio-visual simulations of a park and an urban square were attempted; a series of listening tests were carried out. The subjects were asked to qualify the soundscape in terms...

  1. A Nanoscale Simulation Study of Elastic Properties of Gaspeite

    Directory of Open Access Journals (Sweden)

    Benazzouz Brahim-Khalil

    2015-02-01

    Full Text Available The study of structural and mechanical properties of carbonate rock is an interesting subject in engineering and its different applications. In this paper, the crystal structure of gaspeite (NiCO3 is investigated by carrying out molecular dynamics simulations based on energy minimization technique using an interatomic interaction potential.

  2. Computer simulation study of water using a fluctuating charge model

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Hydrogen bonding in small water clusters is studied through computer simulation methods using a sophisticated, empirical model of interaction developed by Rick et al (S W Rick, S J Stuart and B J Berne 1994 J. Chem. Phys. 101 6141) and others. The model allows for the charges on the interacting sites to ...

  3. The organisation of transactions : studying supply networkd using gaming simulation

    NARCIS (Netherlands)

    Meijer, S.A.

    2009-01-01

    This book studies the organisation of transactions in supply networks. More specifically it investigates the influence of social structure on the mode of organisation in supply networks. To gain new insights, the results in this book have been gathered using gaming simulation as a research method.

  4. Cognitive distance, absorptive capacity and group rationality : A simulation study

    NARCIS (Netherlands)

    Curseu, P.L.; Krehel, O.; Evers, J.H.M.; Muntean, A.

    2014-01-01

    We report the results of a simulation study in which we explore the joint effect of group absorptive capacity (as the average individual rationality of the group members) and cognitive distance (as the distance between the most rational group member and the rest of the group) on the emergence of

  5. Influence of roadside infrastructure on driving behavior: driving simulator study

    NARCIS (Netherlands)

    Horst, A.R.A. van der; Ridder, S. de

    2007-01-01

    This paper describes the results of a driving simulator study that focused on the influence of roadside infrastructure on speed choice and lateral placement of car drivers. A review of the RISER detailed accident database revealed that lateral positioning and speed of the vehicle were two of the

  6. Simulation Study of a Vehicle Production Line for Productivity Improvement

    Directory of Open Access Journals (Sweden)

    M.F.F. Ab Rashid

    2015-06-01

    Full Text Available This paper presents the study of a motorcycle frame production line in a particular company in Malaysia. Due to the high demand, the company needs to increase its production by at least 12% compared with current output. In order to improve productivity, the production-floor data was collected and simulated using the discrete event simulation approach. Later, a number of suggestions for improvement were simulated to identify the effect of the suggestions on productivity. In addition, cost analysis was also undertaken to identify the profit margin for a particular period of time for each suggestion. Simulation results indicate that there are three suggestions that are able to fulfill the 12% volume increment. In the short term, the suggestion to hire an assistant line leader will give instant effect to the profit. Meanwhile, for the medium term, Poka-yoke will give higher profit compared with the others, while in the long term, SOP (standard operating procedure implementation will yield a better profit margin. In future, the simulation of a dynamic demand model for this product is suggested to cope with new trends in the market.

  7. Planetary Simulation Chambers bring Mars to laboratory studies

    Energy Technology Data Exchange (ETDEWEB)

    Mateo-Marti, E.

    2016-07-01

    Although space missions provide fundamental and unique knowledge for planetary exploration, they are always costly and extremely time-consuming. Due to the obvious technical and economical limitations of in-situ planetary exploration, laboratory simulations are among the most feasible research options for making advances in planetary exploration. Therefore, laboratory simulations of planetary environments are a necessary and complementary option to expensive space missions. Simulation chambers are economical, more versatile, and allow for a higher number of experiments than space missions. Laboratory-based facilities are able to mimic the conditions found in the atmospheres and on the surfaces of a majority of planetary objects. Number of relevant applications in Mars planetary exploration will be described in order to provide an understanding about the potential and flexibility of planetary simulation chambers systems: mainly, stability and presence of certain minerals on Mars surface; and microorganisms potential habitability under planetary environmental conditions would be studied. Therefore, simulation chambers will be a promising tools and necessary platform to design future planetary space mission and to validate in-situ measurements from orbital or rover observations. (Author)

  8. Simulation studies of the wavelength-shifting optical module

    Energy Technology Data Exchange (ETDEWEB)

    Di Lorenzo, Vincenzo; Del Pino Rosendo, Esther; Boeser, Sebastian [Johannes Gutenberg-Universitaet, Mainz (Germany); Collaboration: IceCube-Collaboration

    2016-07-01

    The Wavelength-shifting Optical Module (WOM) is a concept for a photon sensor developed for the next generation of the IceCube experiment. The large sensitivity area in combination with the high photon detection efficiency, in particular in the UV region, as well as the low dark noise rates are prominent features of this sensor. A prototype of the WOM is being developed and shows promising results, but some questions are still open. We present here results from a Geant4 simulation used to study the light propagation inside the WOM and the principle reasons of light loss during photon propagation. Using this simulation, it is possible to reproduce the dominant physical effects inside the tube and correlate the simulated results with the experimental ones.

  9. Realistic electricity market simulator for energy and economic studies

    Energy Technology Data Exchange (ETDEWEB)

    Bernal-Agustin, Jose L. [University of Zaragoza, C/Maria de Luna, 3, Zaragoza 50018 (Spain); Contreras, Javier; Conejo, Antonio J. [University of Castilla-La Mancha, Campus Universitario s/n, Ciudad Real 13071 (Spain); Martin-Flores, Raul [Airbus Spain S.L., Paseo John Lennon, Getafe 28906 (Spain)

    2007-01-15

    Electricity market simulators have become a useful tool to train engineers in the power industry. With the maturing of electricity markets throughout the world, there is a need for sophisticated software tools that can replicate the actual behavior of power markets. In most of these markets, power producers/consumers submit production/demand bids and the Market Operator clears the market producing a single price per hour. What makes markets different from each other are the bidding rules and the clearing algorithms to balance the market. This paper presents a realistic simulator of the day-ahead electricity market of mainland Spain. All the rules that govern this market are modeled. This simulator can be used either to train employees by power companies or to teach electricity markets courses in universities. To illustrate the tool, several realistic case studies are presented and discussed. (author)

  10. Numerical simulation and experimental study of explosive projectile devices

    Science.gov (United States)

    Selivanov, V. V.; Gryaznov, E. F.; Goldenko, N. A.; Sudomoev, A. D.; Feldstein, V. A.

    2017-06-01

    A study of explosive-throwing device (ETD) was undertaken to simulate the hypervelocity impact of space debris fragments (SDF) and meteoroids with spacecrafts. The principle of operation of an ETD is based on the cumulative effect in combination with the cut-off head of the cumulative jet, which enables one to simulate a compact particle, such as a meteoroid or a fragment of space debris. Different design schemes of ETD with different composition explosive charge initiation schemes with notably low speeds of the jet cut-off are explored, and a method to control the particle velocity is proposed. Numerical simulation of device modes and basic technical characteristics of experimental testing are investigated.

  11. Pediatric Trauma Boot Camp: A Simulation Curriculum and Pilot Study

    Directory of Open Access Journals (Sweden)

    Ahmad Khobrani

    2018-01-01

    Full Text Available Trauma is a leading cause of morbidity and mortality in infants and children worldwide. Trauma education is one of the most commonly reported deficiencies in pediatric emergency medicine (PEM training. In this study, we describe the creation of a pediatric trauma boot camp in which trainees’ basic knowledge, level of confidence, teamwork, and communication skills are assessed. The primary goal of this pilot study was to create a simulation-based pediatric trauma curriculum for PEM fellows and emergency medicine residents utilizing Kern’s curricular conceptual framework. This was a pilot, prospective, single cohort, exploratory, observational study utilizing survey methodology and a convenience sample. The curriculum consisted of a two-day experience that included confidence surveys, a cognitive multiple-choice questionnaire, and formative and summative simulation scenarios. At the conclusion of this intensive simulation-based trauma boot camp participants reported increased confidence and demonstrated significant improvement in the basic knowledge and performance of the management of pediatric trauma cases in a simulated environment.

  12. Mathematical and computational modeling and simulation fundamentals and case studies

    CERN Document Server

    Moeller, Dietmar P F

    2004-01-01

    Mathematical and Computational Modeling and Simulation - a highly multi-disciplinary field with ubiquitous applications in science and engineering - is one of the key enabling technologies of the 21st century. This book introduces to the use of Mathematical and Computational Modeling and Simulation in order to develop an understanding of the solution characteristics of a broad class of real-world problems. The relevant basic and advanced methodologies are explained in detail, with special emphasis on ill-defined problems. Some 15 simulation systems are presented on the language and the logical level. Moreover, the reader can accumulate experience by studying a wide variety of case studies. The latter are briefly described within the book but their full versions as well as some simulation software demos are available on the Web. The book can be used for University courses of different level as well as for self-study. Advanced sections are marked and can be skipped in a first reading or in undergraduate courses...

  13. Simulation

    DEFF Research Database (Denmark)

    Gould, Derek A; Chalmers, Nicholas; Johnson, Sheena J

    2012-01-01

    Recognition of the many limitations of traditional apprenticeship training is driving new approaches to learning medical procedural skills. Among simulation technologies and methods available today, computer-based systems are topical and bring the benefits of automated, repeatable, and reliable...... performance assessments. Human factors research is central to simulator model development that is relevant to real-world imaging-guided interventional tasks and to the credentialing programs in which it would be used....

  14. Computer Simulation Studies of CTG Triplet Repeat Sequences

    Science.gov (United States)

    Rasaiah, Jayendran. C.; Lynch, Joshua

    1998-03-01

    Long segments of CTG trinucleotide repeats in human DNA are correlated with a class of neurological diseases (myotonic dystrophy, fragile-X syndrome, and Kenndy's disease). These diseases are characterized by genetic anticipation and are thought to arise from replication errors caused by unusual conformations of CTG repeat segments. We have studied the properties of a single short segment of double starnded DNA with CTG repeats in 0.5 M sodium chloride solution with molecular dynamics simulations. The simulations are carried out in the micro canonical ensemble using an all-atom force field with CHARMM parameters. The TIPS3 water model is used to simulate a molecular solvent. Electrostatic interactions are calculated by Ewald summation and the equations of motion integrated using a Verlet algorithm in conjunction with SHAKE constrained dynamics to maintain bond lengths. The simulation of CTG repeat sequence is compared with a control system containing CAG triplet repeats to determine possible differencesin the conformation and elasticity of the two sequences.

  15. MHD simulation study of compact toroid injection into magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Yoshio; Kishimoto, Yasuaki [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Hayashi, Takaya [National Inst. for Fusion Science, Toki, Gifu (Japan)

    2000-06-01

    To understand the fuelling process in a fusion device by a compact toroid (CT) plasmoid injection method, we have carried out MHD numerical simulations where a spheromak-like CT (SCT) is injected into a magnetized target plasma region. So far, we revealed that the penetration depth of the SCT plasma becomes shorter than that estimated from the conducting sphere (CS) model, because in the simulation the Lorentz force of the target magnetic field sequentially decelerates the injected SCT while in the CS model only the magnetic pressure force acts as the deceleration mechanism. In this study, we represent the new theoretical model where the injected SCT is decelerated by both the magnetic pressure force and the magnetic tension force (we call it the non-slipping sphere (NS) model) and investigate in detail the deceleration mechanism of the SCT by comparison with simulation results. As a result, it is found that the decrease of the SCT kinetic energy in the simulation coincides with that in the NS model more than in the CS model. It means that not only the magnetic pressure force but also the magnetic tension force acts as the deceleration mechanism of the SCT. Furthermore, it is revealed that magnetic reconnection between the SCT magnetic field and the target magnetic field plays a role to relax the SCT deceleration. (author)

  16. Real versus Simulated Mobile Phone Exposures in Experimental Studies

    Directory of Open Access Journals (Sweden)

    Dimitris J. Panagopoulos

    2015-01-01

    Full Text Available We examined whether exposures to mobile phone radiation in biological/clinical experiments should be performed with real-life Electromagnetic Fields (EMFs emitted by commercially available mobile phone handsets, instead of simulated EMFs emitted by generators or test phones. Real mobile phone emissions are constantly and unpredictably varying and thus are very different from simulated emissions which employ fixed parameters and no variability. This variability is an important parameter that makes real emissions more bioactive. Living organisms seem to have decreased defense against environmental stressors of high variability. While experimental studies employing simulated EMF-emissions present a strong inconsistency among their results with less than 50% of them reporting effects, studies employing real mobile phone exposures demonstrate an almost 100% consistency in showing adverse effects. This consistency is in agreement with studies showing association with brain tumors, symptoms of unwellness, and declines in animal populations. Average dosimetry in studies with real emissions can be reliable with increased number of field measurements, and variation in experimental outcomes due to exposure variability becomes less significant with increased number of experimental replications. We conclude that, in order for experimental findings to reflect reality, it is crucially important that exposures be performed by commercially available mobile phone handsets.

  17. Studying and simulating transformer configuration to improve power quality

    Directory of Open Access Journals (Sweden)

    Oscar J. Peña Huaringa

    2011-06-01

    Full Text Available This paper presents a study and simulation of transformer configurations to improve power quality; it provides theoretical support based on the expansion of the Fourier series and analysis of symmetrical components. A test system was set up in the laboratory, taking measurements and checking configuration effectiveness in reducing the system’s harmonic content. The configurations were modelled with PSCAD / EMTDC software, using two 6 pulse rectifiers as test loads and two variable speed drives.

  18. Regression models for public health surveillance data: a simulation study.

    Science.gov (United States)

    Kim, H; Kriebel, D

    2009-11-01

    Poisson regression is now widely used in epidemiology, but researchers do not always evaluate the potential for bias in this method when the data are overdispersed. This study used simulated data to evaluate sources of overdispersion in public health surveillance data and compare alternative statistical models for analysing such data. If count data are overdispersed, Poisson regression will not correctly estimate the variance. A model called negative binomial 2 (NB2) can correct for overdispersion, and may be preferred for analysis of count data. This paper compared the performance of Poisson and NB2 regression with simulated overdispersed injury surveillance data. Monte Carlo simulation was used to assess the utility of the NB2 regression model as an alternative to Poisson regression for data which had several different sources of overdispersion. Simulated injury surveillance datasets were created in which an important predictor variable was omitted, as well as with an incorrect offset (denominator). The simulations evaluated the ability of Poisson regression and NB2 to correctly estimate the true determinants of injury and their confidence intervals. The NB2 model was effective in reducing overdispersion, but it could not reduce bias in point estimates which resulted from omitting a covariate which was a confounder, nor could it reduce bias from using an incorrect offset. One advantage of NB2 over Poisson for overdispersed data was that the confidence interval for a covariate was considerably wider with the former, providing an indication that the Poisson model did not fit well. When overdispersion is detected in a Poisson regression model, the NB2 model should be fit as an alternative. If there is no longer overdispersion, then the NB2 results may be preferred. However, it is important to remember that NB2 cannot correct for bias from omitted covariates or from using an incorrect offset.

  19. A case study using a daylight simulation tool

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, D.C. [Light Foundry, Berkeley, CA (United States)

    2005-07-01

    Building simulation tools are developed by professionals from a range of backgrounds, each with their own capacities, requirements and training. The building performance community is greatly interested in comprehending how users and organizations adopt and work with simulation packages to solve design problems. This paper presented a detailed case study of how a designer used a lighting design prototype that relies on screen, voice and gesture data recorded on a digital camcorder. The new daylight simulation tool was used to plan a lighting system at the Pacific Energy Center in San Francisco, California. The participant, who had 13 years of industry experience, was asked how she would use the tool for designing a lighting system for a pentagonal office with 3 windows. Discourse analysis codified and interpreted the designer's talk and gesture during an extended user study. An excerpt of 2 hours of recorded data was presented to identify the usability, learning and professional adoption issues. The study revealed how a professional interacts with the software on a hypothetical design problem. The 3 stages of the participant's user test all showed an increased mastery using the visualization tool. The lighting quality of the proposed room was improved by balancing daylight with electric lighting systems. Professional training was identified as being both the enabling and disabling factor for use. 7 refs., 6 tabs., 7 figs.

  20. Feasibility study for a generalized gate logic software simulator

    Science.gov (United States)

    Mcgough, J. G.

    1983-01-01

    Unit-delay simulation, event driven simulation, zero-delay simulation, simulation techniques, 2-valued versus multivalued logic, network initialization, gate operations and alternate network representations, parallel versus serial mode simulation fault modelling, extension of multiprocessor systems, and simulation timing are discussed. Functional level networks, gate equivalent circuits, the prototype BDX-930 network model, fault models, identifying detected faults for BGLOSS are discussed. Preprocessor tasks, postprocessor tasks, executive tasks, and a library of bliss coded macros for GGLOSS are also discussed.

  1. Can We Study Autonomous Driving Comfort in Moving-Base Driving Simulators? A Validation Study.

    Science.gov (United States)

    Bellem, Hanna; Klüver, Malte; Schrauf, Michael; Schöner, Hans-Peter; Hecht, Heiko; Krems, Josef F

    2017-05-01

    To lay the basis of studying autonomous driving comfort using driving simulators, we assessed the behavioral validity of two moving-base simulator configurations by contrasting them with a test-track setting. With increasing level of automation, driving comfort becomes increasingly important. Simulators provide a safe environment to study perceived comfort in autonomous driving. To date, however, no studies were conducted in relation to comfort in autonomous driving to determine the extent to which results from simulator studies can be transferred to on-road driving conditions. Participants ( N = 72) experienced six differently parameterized lane-change and deceleration maneuvers and subsequently rated the comfort of each scenario. One group of participants experienced the maneuvers on a test-track setting, whereas two other groups experienced them in one of two moving-base simulator configurations. We could demonstrate relative and absolute validity for one of the two simulator configurations. Subsequent analyses revealed that the validity of the simulator highly depends on the parameterization of the motion system. Moving-base simulation can be a useful research tool to study driving comfort in autonomous vehicles. However, our results point at a preference for subunity scaling factors for both lateral and longitudinal motion cues, which might be explained by an underestimation of speed in virtual environments. In line with previous studies, we recommend lateral- and longitudinal-motion scaling factors of approximately 50% to 60% in order to obtain valid results for both active and passive driving tasks.

  2. IPv6 Routing Protocol for Low Power and Lossy Sensor Networks Simulation Studies

    National Research Council Canada - National Science Library

    Leila Ben Saad; Cedric Chauvenet; Bernard Tourancheau

    2012-01-01

    ...) using the RPL capable COOJA simulator, augmented by our own PLC module. Our studies give two new RPL evaluations and show the interest of choosing a simulation tool adapted to the simulation aim...

  3. Leading teams during simulated pediatric emergencies: a pilot study

    Science.gov (United States)

    Coolen, Ester H; Draaisma, Jos M; den Hamer, Sabien; Loeffen, Jan L

    2015-01-01

    Purpose Leadership has been identified as a key variable for the functioning of teams and as one of the main reasons for success or failure of team-based work systems. Pediatricians often function as team leaders in the resuscitation of a critically ill child. However, pediatric residents often report having little opportunity to perform in the role of team leader during residency. In order to gain more insight into leadership skills and behaviors, we classified leadership styles of pediatric residents during simulated emergencies. Methods We conducted a prospective quantitative study to investigate leadership styles used by pediatric residents during simulated emergencies with clinical deterioration of a child at a pediatric ward. Using videotaped scenarios of 48 simulated critical events among 12 residents, we were able to classify verbal and nonverbal communication into different leadership styles according to the situational leadership theory. Results The coaching style (mean 54.5%, SD 7.8) is the most frequently applied by residents, followed by the directing style (mean 35.6%, SD 4.1). This pattern conforms to the task- and role-related requirements in our scenarios and it also conforms to the concept of situational leadership. We did not find any significant differences in leadership style according to the postgraduate year or scenario content. Conclusion The model used in this pilot study helps us to gain a better understanding of the development of effective leadership behavior and supports the applicability of situational leadership theory in training leadership skills during residency. PMID:25610010

  4. Leading teams during simulated pediatric emergencies: a pilot study.

    Science.gov (United States)

    Coolen, Ester H; Draaisma, Jos M; den Hamer, Sabien; Loeffen, Jan L

    2015-01-01

    Leadership has been identified as a key variable for the functioning of teams and as one of the main reasons for success or failure of team-based work systems. Pediatricians often function as team leaders in the resuscitation of a critically ill child. However, pediatric residents often report having little opportunity to perform in the role of team leader during residency. In order to gain more insight into leadership skills and behaviors, we classified leadership styles of pediatric residents during simulated emergencies. We conducted a prospective quantitative study to investigate leadership styles used by pediatric residents during simulated emergencies with clinical deterioration of a child at a pediatric ward. Using videotaped scenarios of 48 simulated critical events among 12 residents, we were able to classify verbal and nonverbal communication into different leadership styles according to the situational leadership theory. The coaching style (mean 54.5%, SD 7.8) is the most frequently applied by residents, followed by the directing style (mean 35.6%, SD 4.1). This pattern conforms to the task- and role-related requirements in our scenarios and it also conforms to the concept of situational leadership. We did not find any significant differences in leadership style according to the postgraduate year or scenario content. The model used in this pilot study helps us to gain a better understanding of the development of effective leadership behavior and supports the applicability of situational leadership theory in training leadership skills during residency.

  5. Comparative Simulation Study on Synchronous Generators Sudden Short Circuits

    Directory of Open Access Journals (Sweden)

    Lucian Lupşa-Tătaru

    2009-01-01

    Full Text Available Although of a great extent in time, the research works directed at studying transients in synchronous generators have not yet provided fully sufficient comparative studies in respect to sudden short circuits of the machine. The present paper puts forward novel and comprehensive process models for dynamic simulation of short circuit faults of initially unloaded synchronous generators, using the generalized d-q-0 mathematical model as starting point in derivation. Distinct from the time-domain analysis, the technique proposed here allows an effective comparative overview by employing a specialized procedure to perform repeated time-domain simulations accompanied by peak values recording for the various circumstances. The time consuming matrix numerical inversion at each step of integration, usually performed when selecting currents as state variables, is eliminated by advancing the process models in a convenient split matrix form that allows the symbolic processing. Also, the computational efficiency is being increased by introducing a set of auxiliary variables common to different state equations. The models derivation is carried out without altering the structural equations of the generalized d-q-0 mathematical model of synchronous generators whilst the simulation results are both compared and discussed in detail.

  6. Simulation study of secondary electron images in scanning ion microscopy

    CERN Document Server

    Ohya, K

    2003-01-01

    The target atomic number, Z sub 2 , dependence of secondary electron yield is simulated by applying a Monte Carlo code for 17 species of metals bombarded by Ga ions and electrons in order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM). In addition to the remarkable reversal of the Z sub 2 dependence between the Ga ion and electron bombardment, a fine structure, which is correlated to the density of the conduction band electrons in the metal, is calculated for both. The brightness changes of the secondary electron images in SIM and SEM are simulated using Au and Al surfaces adjacent to each other. The results indicate that the image contrast in SIM is much more sensitive to the material species and is clearer than that for SEM. The origin of the difference between SIM and SEM comes from the difference in the lateral distribution of secondary electrons excited within the escape depth.

  7. AUV-Based Plume Tracking: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Awantha Jayasiri

    2016-01-01

    Full Text Available This paper presents a simulation study of an autonomous underwater vehicle (AUV navigation system operating in a GPS-denied environment. The AUV navigation method makes use of underwater transponder positioning and requires only one transponder. A multirate unscented Kalman filter is used to determine the AUV orientation and position by fusing high-rate sensor data and low-rate information. The paper also proposes a gradient-based, efficient, and adaptive novel algorithm for plume boundary tracking missions. The algorithm follows a centralized approach and it includes path optimization features based on gradient information. The proposed algorithm is implemented in simulation on the AUV-based navigation system and successful boundary tracking results are obtained.

  8. Shear Viscosity of Liquid Potassium and Cesium: a Simulation Study

    Directory of Open Access Journals (Sweden)

    Meyer Nadège

    2017-01-01

    Full Text Available The density and temperature dependences of the shear viscosity of liquid potassium and cesium are studied. The stress autocorrelation function is calculated from equilibrium molecular dynamics simulations. Using the Green-Kubo formula, the shear viscosity is obtained. Interionic interactions are calculated by Fiolhais potential and are validated by comparison between simulation and experimental data along the liquid-gas coexistence curve for K and Cs. For both metals, three isochors and one isotherm are investigated. The recently proposed relation in [Phys. Rev. B 93, 214203 (2016] is tested in the cases of K and Cs and it appears that this function reproduces qualitatively and quantitatively well the behavior of each element.

  9. Simulation and experimental study of resin flow in fibre fabrics

    Science.gov (United States)

    Yan, Fei; Yan, Shilin; Li, Yongjing

    2017-06-01

    Liquid Composite Moulding (LCM) is gradually becoming the most competitive manufacturing technology for producing large composite parts with complex geometry with high quality and low cost. These parts include those for airplanes, wind turbine blades and automobile components. Fibre fabrics in liquid composite moulding can be considered as dual-scale porous media. In different gap scales, an unsaturated flow is produced during the mould filling process. This particular flow behaviour deviates from the traditional Darcy’s law, which is used to calculate the filling pressure and will cause errors. According to sink theory, the unsaturated flow characteristics of this dual-scale porous media were studied in this paper, and a FEM solution program was developed. The results showed that the pressure curves against the position which simulated by sink functions were departure from the position of traditional theory. In addition, the simulation results of partially-saturated region were consistent with the experimental data.

  10. A Quantitative Study of Simulated Bicuspid Aortic Valves

    Science.gov (United States)

    Szeto, Kai; Nguyen, Tran; Rodriguez, Javier; Pastuszko, Peter; Nigam, Vishal; Lasheras, Juan

    2010-11-01

    Previous studies have shown that congentially bicuspid aortic valves develop degenerative diseases earlier than the standard trileaflet, but the causes are not well understood. It has been hypothesized that the asymmetrical flow patterns and turbulence found in the bileaflet valves together with abnormally high levels of strain may result in an early thickening and eventually calcification and stenosis. Central to this hypothesis is the need for a precise quantification of the differences in the strain rate levels between bileaflets and trileaflet valves. We present here some in-vitro dynamic measurements of the spatial variation of the strain rate in pig aortic vales conducted in a left ventricular heart flow simulator device. We measure the strain rate of each leaflet during the whole cardiac cycle using phase-locked stereoscopic three-dimensional image surface reconstruction techniques. The bicuspid case is simulated by surgically stitching two of the leaflets in a normal valve.

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

    Directory of Open Access Journals (Sweden)

    S. Simon

    2006-05-01

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

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

    Directory of Open Access Journals (Sweden)

    S. Simon

    2006-05-01

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

  13. Leading teams during simulated pediatric emergencies: a pilot study

    Directory of Open Access Journals (Sweden)

    Coolen EH

    2015-01-01

    Full Text Available Ester H Coolen,1 Jos M Draaisma,2 Sabien den Hamer,3 Jan L Loeffen2 1Department of Pediatric Surgery, Amalia Children’s Hospital, Radboud University Medical Center, 2Department of Pediatrics, Amalia Children’s Hospital, Radboud University Medical Center, 3Department of Communication Science, Radboud University, Nijmegen, the Netherlands Purpose: Leadership has been identified as a key variable for the functioning of teams and as one of the main reasons for success or failure of team-based work systems. Pediatricians often function as team leaders in the resuscitation of a critically ill child. However, pediatric residents often report having little opportunity to perform in the role of team leader during residency. In order to gain more insight into leadership skills and behaviors, we classified leadership styles of pediatric residents during simulated emergencies. Methods: We conducted a prospective quantitative study to investigate leadership styles used by pediatric residents during simulated emergencies with clinical deterioration of a child at a pediatric ward. Using videotaped scenarios of 48 simulated critical events among 12 residents, we were able to classify verbal and nonverbal communication into different leadership styles according to the situational leadership theory. Results: The coaching style (mean 54.5%, SD 7.8 is the most frequently applied by residents, followed by the directing style (mean 35.6%, SD 4.1. This pattern conforms to the task- and role-related requirements in our scenarios and it also conforms to the concept of situational leadership. We did not find any significant differences in leadership style according to the postgraduate year or scenario content. Conclusion: The model used in this pilot study helps us to gain a better understanding of the development of effective leadership behavior and supports the applicability of situational leadership theory in training leadership skills during residency. Keywords

  14. Study on advancement of in vivo counting using mathematical simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kinase, Sakae [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-05-01

    To obtain an assessment of the committed effective dose, individual monitoring for the estimation of intakes of radionuclides is required. For individual monitoring of exposure to intakes of radionuclides, direct measurement of radionuclides in the body - in vivo counting- is very useful. To advance in a precision in vivo counting which fulfills the requirements of ICRP 1990 recommendations, some problems, such as the investigation of uncertainties in estimates of body burdens by in vivo counting, and the selection of the way to improve the precision, have been studied. In the present study, a calibration technique for in vivo counting application using Monte Carlo simulation was developed. The advantage of the technique is that counting efficiency can be obtained for various shapes and sizes that are very difficult to change for phantoms. To validate the calibration technique, the response functions and counting efficiencies of a whole-body counter installed in JAERI were evaluated using the simulation and measurements. Consequently, the calculations are in good agreement with the measurements. The method for the determination of counting efficiency curves as a function of energy was developed using the present technique and a physiques correction equation was derived from the relationship between parameters of correction factor and counting efficiencies of the JAERI whole-body counter. The uncertainties in body burdens of {sup 137}Cs estimated with the JAERI whole-body counter were also investigated using the Monte Carlo simulation and measurements. It was found that the uncertainties of body burdens estimated with the whole-body counter are strongly dependent on various sources of uncertainty such as radioactivity distribution within the body and counting statistics. Furthermore, the evaluation method of the peak efficiencies of a Ge semi-conductor detector was developed by Monte Carlo simulation for optimum arrangement of Ge semi-conductor detectors for

  15. Using DOE Commercial Reference Buildings for Simulation Studies: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Field, K.; Deru, M.; Studer, D.

    2010-08-01

    The U.S. Department of Energy developed 256 EnergyPlus models for use in studies that aim to characterize about 70% of the U.S. commercial building stock. Sixteen building types - including restaurants, health care, schools, offices, supermarkets, retail, lodging, and warehouses - are modeled across 16 cities to represent the diversity of U.S. climate zones. Weighting factors have been developed to combine the models in proportions similar to those of the McGraw-Hill Construction Projects Starts Database for 2003-2007. This paper reviews the development and contents of these models and their applications in simulation studies.

  16. Energy flux simulation in heterogeneous cropland - a two year study

    Science.gov (United States)

    Klein, Christian; Thieme, Christoph; Biernath, Christian; Heinlein, Florian; Priesack, Eckart

    2016-04-01

    Recent studies show that uncertainties in regional and global climate and weather simulations are partly due to inadequate descriptions of the energy flux exchanges between the land surface and the atmosphere [Stainforth et al. 2005]. One major shortcoming is the limitation of the grid-cell resolution, which is recommended to be about at least 3x3 km² in most models due to limitations in the model physics. To represent each individual grid cell most models select one dominant soil type and one dominant land use type. This resolution, however, is often too coarse in regions where the spatial heterogeneity of soil and land use types are high, e.g. in Central Europe. The relevance of vegetation (e.g. crops), ground cover, and soil properties to the moisture and energy exchanges between the land surface and the atmosphere is well known [McPherson 2007], but the impact of vegetation growth dynamics on energy fluxes is only partly understood [Gayler et al. 2014]. An elegant method to avoid the shortcoming of grid cell resolution is the so called mosaic approach. This approach is part of the recently developed ecosystem model framework Expert-N [Biernath et al. 2013] . The aim of this study was to analyze the impact of the characteristics of five managed field plots, planted with winter wheat, potato and maize on the near surface soil moistures and on the near surface energy flux exchanges of the soil-plant-atmosphere interface. The simulated energy fluxes were compared with eddy flux tower measurements between the respective fields at the research farm Scheyern, North-West of Munich, Germany. To perform these simulations, we coupled the ecosystem model Expert-N to an analytical footprint model [Mauder & Foken 2011] . The coupled model system has the ability to calculate the mixing ratio of the surface energy fluxes at a given point within one grid cell (in this case at the flux tower between the two fields). The approach accounts for the temporarily and spatially

  17. Monte Carlo simulations and dosimetric studies of an irradiation facility

    Science.gov (United States)

    Belchior, A.; Botelho, M. L.; Vaz, P.

    2007-09-01

    There is an increasing utilization of ionizing radiation for industrial applications. Additionally, the radiation technology offers a variety of advantages in areas, such as sterilization and food preservation. For these applications, dosimetric tests are of crucial importance in order to assess the dose distribution throughout the sample being irradiated. The use of Monte Carlo methods and computational tools in support of the assessment of the dose distributions in irradiation facilities can prove to be economically effective, representing savings in the utilization of dosemeters, among other benefits. One of the purposes of this study is the development of a Monte Carlo simulation, using a state-of-the-art computational tool—MCNPX—in order to determine the dose distribution inside an irradiation facility of Cobalt 60. This irradiation facility is currently in operation at the ITN campus and will feature an automation and robotics component, which will allow its remote utilization by an external user, under REEQ/996/BIO/2005 project. The detailed geometrical description of the irradiation facility has been implemented in MCNPX, which features an accurate and full simulation of the electron-photon processes involved. The validation of the simulation results obtained was performed by chemical dosimetry methods, namely a Fricke solution. The Fricke dosimeter is a standard dosimeter and is widely used in radiation processing for calibration purposes.

  18. Experiment and Simulation Study on the Amorphous Silicon Photovoltaic Walls

    Directory of Open Access Journals (Sweden)

    Wenjie Zhang

    2014-01-01

    Full Text Available Based on comparative study on two amorphous silicon photovoltaic walls (a-Si PV walls, the temperature distribution and the instant power were tested; and with EnergyPlus software, similar models of the walls were built to simulate annual power generation and air conditioning load. On typical sunshine day, the corresponding position temperature of nonventilated PV wall was generally 0.5~1.5°C higher than that of ventilated one, while the power generation was 0.2%~0.4% lower, which was consistent with the simulation results with a difference of 0.41% in annual energy output. As simulation results, in summer, comparing the PV walls with normal wall, the heat per unit area of these two photovoltaic walls was 5.25 kWh/m2 (nonventilated and 0.67 kWh/m2 (ventilated higher, respectively. But in winter the heat loss of nonventilated one was smaller, while ventilated PV wall was similar to normal wall. To annual energy consumption of heating and cooling, the building with ventilated PV wall and normal wall was also similar but slightly better than nonventilated one. Therefore, it is inferred that, at low latitudes, such as Zhuhai, China, air gap ventilation is suitable, while the length to thickness ratio of the air gap needs to be taken into account.

  19. Outgassing study of spacecraft materials and contaminant transport simulations

    Science.gov (United States)

    Wong, Chung M.; Labatete-Goeppinger, Aura C.; Fowler, Jesse D.; Easton, Myriam P.; Liu, De-Ling

    2016-09-01

    Contamination control plays an important role in sustaining spacecraft performance. One spacecraft degradation mechanism involves long-term on-orbit molecular outgassing from spacecraft materials. The outgassed molecules may accumulate on thermal control surfaces and/or optics, causing degradation. In this study, we performed outgassing measurements of multiple spacecraft materials, including adhesives, Nylon Velcro, and other assembly materials through a modified ASTM E595 test method. The modified ASTM E595 test had the source and receiver temperature remained at 125°C and 25°C, respectively, but with prolonged outgassing periods of two weeks. The condensable contaminants were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography/Mass Spectrometry (GC/MS) to determine their spectral transmission and chemical composition. The FTIR spectra showed several spacecraft materials, primarily adhesives and potting materials, exhibiting slight absorption from contaminants consisting of hydroxyl groups and carboxylic acids. To gain insight into molecular contaminant transport, simulations were conducted to characterize contaminant accumulation inside a hypothetical space system cavity. The simulation indicated that contaminant molecules bouncing inside the hypothetical payload cavity can lead to deposition on colder surfaces, even though large openings are available to provide venting pathways for escaping to space. The newly established molecular contaminant transport simulation capability holds the promise of providing quantitative guidance for future spacecraft and its venting design.

  20. Empirical study of simulated two-planet microlensing events

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wei; Gould, Andrew; Penny, Matthew [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Mao, Shude [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Gendron, Rieul, E-mail: weizhu@astronomy.ohio-state.edu [Jodrell Bank Centre for Astrophysics, University of Manchester, Alan Turing Building, Manchester M13 9PL (United Kingdom)

    2014-10-10

    We undertake the first study of two-planet microlensing models recovered from simulations of microlensing events generated by realistic multiplanet systems in which 292 planetary events, including 16 two-planet events, were detected from 6690 simulated light curves. We find that when two planets are recovered, their parameters are usually close to those of the two planets in the system most responsible for the perturbations. However, in 1 of the 16 examples, the apparent mass of both detected planets was more than doubled by the unmodeled influence of a third, massive planet. This fraction is larger than but statistically consistent with the roughly 1.5% rate of serious mass errors due to unmodeled planetary companions for the 274 cases from the same simulation in which a single planet is recovered. We conjecture that an analogous effect due to unmodeled stellar companions may occur more frequently. For 7 out of 23 cases in which two planets in the system would have been detected separately, only one planet was recovered because the perturbations due to the two planets had similar forms. This is a small fraction (7/274) of all recovered single-planet models, but almost a third of all events that might plausibly have led to two-planet models. Still, in these cases, the recovered planet tends to have parameters similar to one of the two real planets most responsible for the anomaly.

  1. Experimental study and simulations of infiltration in evapotranspiration landfill covers

    Directory of Open Access Journals (Sweden)

    Wen-xian Zhang

    2009-09-01

    Full Text Available Various cover systems have been designed for landfill sites in order to minimize infiltration (percolation into the underlying waste. This study evaluated the soil water balance performance of evapotranspiration covers (ET covers and simulated percolation in the systems using the active region model (ARM. Experiments were conducted to measure water flow processes and water balance components in a bare soil cover and different ET covers. Results showed that vegetation played a critical role in controlling the water balance of the ET covers. In soil profiles of 60-cm depth with and without vegetation cover, the maximum soil water storage capacities were 97.2 mm and 62.8 mm, respectively. The percolation amount in the bare soil was 2.1 times that in the vegetation-covered soil. The ARM simulated percolation more accurately than the continuum model because it considered preferential flow. Numerical simulation results also indicated that using the ET cover system was an effective way of removing water through evapotranspiration, thus reducing percolation.

  2. FES-Assisted Walking with Spring Brake Orthosis: Simulation Studies

    Directory of Open Access Journals (Sweden)

    R. Jailani

    2011-01-01

    Full Text Available This paper presents a simulation of bipedal locomotion to generate stimulation pulses for activating muscles for paraplegic walking with wheel walker using functional electrical stimulation (FES with spring brake orthosis (SBO. A new methodology for paraplegic gait, based on exploiting natural dynamics of human gait, is introduced. The work is a first effort towards restoring natural like swing phase in paraplegic gait through a new hybrid orthosis, referred to as spring brake orthosis (SBO. This mechanism simplifies the control task and results in smooth motion and more-natural like trajectory produced by the flexion reflex for gait in spinal cord injured subjects. SBO can eliminate reliance on the withdrawal reflex and foot-ground clearance without extra upper body effort. The stored energy in the spring of SBO is used to replace stimulation pulses in knee flexion and reduce total required torque for the paraplegic walking with wheel walker. The study is carried out with a model of humanoid with wheel walker using the Visual Nastran (Vn4D dynamic simulation software. Stimulated muscle model of quadriceps is developed for knee extension. Fuzzy logic control (FLC is developed in Matlab/Simulink to regulate the muscle stimulation pulse-width required to drive FES-assisted walking gait and the computed motion is visualised in graphic animation from Vn4D. The simulation results show that SBO can be successfully used with FES for paraplegic walking with wheel walker with all the advantages discussed over the current hybrid orthoses available.

  3. Simulation Based Studies in Software Engineering: A Matter of Validity

    Directory of Open Access Journals (Sweden)

    Breno Bernard Nicolau de França

    2015-04-01

    Full Text Available Despite the possible lack of validity when compared with other science areas, Simulation-Based Studies (SBS in Software Engineering (SE have supported the achievement of some results in the field. However, as it happens with any other sort of experimental study, it is important to identify and deal with threats to validity aiming at increasing their strength and reinforcing results confidence. OBJECTIVE: To identify potential threats to SBS validity in SE and suggest ways to mitigate them. METHOD: To apply qualitative analysis in a dataset resulted from the aggregation of data from a quasi-systematic literature review combined with ad-hoc surveyed information regarding other science areas. RESULTS: The analysis of data extracted from 15 technical papers allowed the identification and classification of 28 different threats to validity concerned with SBS in SE according Cook and Campbell’s categories. Besides, 12 verification and validation procedures applicable to SBS were also analyzed and organized due to their ability to detect these threats to validity. These results were used to make available an improved set of guidelines regarding the planning and reporting of SBS in SE. CONCLUSIONS: Simulation based studies add different threats to validity when compared with traditional studies. They are not well observed and therefore, it is not easy to identify and mitigate all of them without explicit guidance, as the one depicted in this paper.

  4. Large Scale Simulation Platform for NODES Validation Study

    Energy Technology Data Exchange (ETDEWEB)

    Sotorrio, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Qin, Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Min, L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-04-27

    This report summarizes the Large Scale (LS) simulation platform created for the Eaton NODES project. The simulation environment consists of both wholesale market simulator and distribution simulator and includes the CAISO wholesale market model and a PG&E footprint of 25-75 feeders to validate the scalability under a scenario of 33% RPS in California with additional 17% of DERS coming from distribution and customers. The simulator can generate hourly unit commitment, 5-minute economic dispatch, and 4-second AGC regulation signals. The simulator is also capable of simulating greater than 10k individual controllable devices. Simulated DERs include water heaters, EVs, residential and light commercial HVAC/buildings, and residential-level battery storage. Feeder-level voltage regulators and capacitor banks are also simulated for feeder-level real and reactive power management and Vol/Var control.

  5. A Preliminary Study of Heat Strain Using Modelling and Simulation

    Science.gov (United States)

    2006-05-01

    opérationnelles s’imposent. Le personnel militaire est confronté à un certain nombre de risques qui doivent être réduits, et la fatigue due à la chaleur n’est...collaborative agreement now in place, DRDC Toronto has a mechanism to exchange models or data with QinetiQ14 and future exchanges should proceed more...A preliminary study of heat strain using modelling and simulation (U) Étude préliminaire sur la fatigue due à la chaleur à l’aide de la modélisation

  6. Tax amnesties, justice perceptions, and filing behavior: a simulation study.

    Science.gov (United States)

    Rechberger, Silvia; Hartner, Martina; Kirchler, Erich; Hämmerle, Franziska

    2010-04-01

    A simulation study demonstrates the influence of perceived justice of a tax amnesty on subsequent tax compliance. In addition, it investigates how the amnesty is perceived to serve the punishment objectives retribution (i.e., giving offenders what they "deserve") and value restoration (i.e., restoring the values violated by tax evasion). Hierarchical regression analysis revealed the expected positive influence of justice on subsequent tax compliance. However, when the influence of punishment objectives was controlled for, the influence of justice disappeared, while retribution and value restoration showed positive effects on post-amnesty tax compliance.

  7. Study on Simulation of Machining Errors Caused by Cutting Force

    Institute of Scientific and Technical Information of China (English)

    SHAO Xiaodong; ZHANG Liu; LIN Zhaoxu

    2006-01-01

    Machining errors caused by cutting force are studied in this paper, and an algorithm to simulate errors is putted forward. In the method, continuous machining process is separated into many machining moments. The deformation of work-piece and cutter at every moment is calculated by finite element method. The machined work-piece is gained by Boolean operation between deformed work-piece and cutter. By analyzing data of final work-piece, machining errors are predicted. The method is proved true by experiment.

  8. Simulation study of the parallax effect of gaseous detectors

    Science.gov (United States)

    Wang, Xiao-Hu; Wu, Jun-Long; Li, Jiang-Bo

    2012-11-01

    A simulation study of the parallax effect of gaseous detectors using the Garfield program is reported. A method that mainly uses non-uniform cathode potentials to reduce the parallax error of planar type gas detectors is described. By applying it to MWPC and Micro-pattern gas detectors, the method reduces the parallax broadening with very good results. For a 13° incidence track, the width (FWHM) of the parallax broadening is reduced to less than 20% of the normal one after using the special cathode potentials.

  9. M3D project for simulation studies of plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Park, W.; Belova, E.V.; Fu, G.Y. [Princeton Univ., NJ (United States). Plasma Physics Lab.; Strauss, H.R. [New York Univ., NY (United States); Sugiyama, L.E. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

    1998-12-31

    The M3D (Multi-level 3D) project carries out simulation studies of plasmas of various regimes using multi-levels of physics, geometry, and mesh schemes in one code package. This paper and papers by Strauss, Sugiyama, and Belova in this workshop describe the project, and present examples of current applications. The currently available physics models of the M3D project are MHD, two-fluids, gyrokinetic hot particle/MHD hybrid, and gyrokinetic particle ion/two-fluid hybrid models. The code can be run with both structured and unstructured meshes.

  10. A simulation study of marrow fat effect on bone biomechanics.

    Science.gov (United States)

    Ma, Heather T; Ren, Rong; Chen, Yang; Griffith, James F; Leung, Ping-Chung; Zhang, Pu

    2014-01-01

    Bone marrow was assumed to be negligible on the aspect of bone mechanical behavior, where bone mass and bone mineral density were most studied. As a result, if the bone marrow, especially the marrow fat, plays a role in the bone mechanical properties is unknown yet. Marrow fat content was found increased in osteoporotic bone. However, the relationship between such change of bone marrow and bone strength is not clear yet. This study was proposed to investigate the effect of marrow fat on the bone biomechanical performance by computer simulations. A finite element model was established based on trabecular structure extracted from quantitative CT at L3 vertebrae. Simulations were conducted on the models with and without marrow fat under the same condition, respectively. The results showed that the cancellous bone with marrow fat had a 7.56%~18.81% higher maximum stress in trabeculae. Further, trabeculae with higher Young's modulus tend to sustain a higher maximum compressive stress when considering the marrow fat. As a conclusion, the marrow fat has effect on bone biomechanics, which cannot be ignored. Such effect in osteoporosis should be further investigated in deep.

  11. Plasma boundaries at Mars: a 3-D simulation study

    Directory of Open Access Journals (Sweden)

    A. Bößwetter

    2004-12-01

    Full Text Available The interaction of the solar wind with the ionosphere of planet Mars is studied using a three-dimensional hybrid model. Mars has only a weak intrinsic magnetic field, and consequently its ionosphere is directly affected by the solar wind. The gyroradii of the solar wind protons are in the range of several hundred kilometers and therefore comparable with the characteristic scales of the interaction region. Different boundaries emerge from the interaction of the solar wind with the continuously produced ionospheric heavy-ion plasma, which could be identified as a bow shock (BS, ion composition boundary (ICB and magnetic pile up boundary (MPB, where the latter both turn out to coincide. The simulation results regarding the shape and position of these boundaries are in good agreement with the measurements made by Phobos-2 and MGS spacecraft. It is shown that the positions of these boundaries depend essentially on the ionospheric production rate, the solar wind ram pressure, and the often unconsidered electron temperature of the ionospheric heavy ion plasma. Other consequences are rays of planetary plasma in the tail and heavy ion plasma clouds, which are stripped off from the dayside ICB region by some instability.

    Key words. Magnetospheric physics (solar wind interactions with unmagnetized bodies – Space plasma physics (discontinuities; numerical simulation studies

  12. Plasma boundaries at Mars: a 3-D simulation study

    Directory of Open Access Journals (Sweden)

    A. Bößwetter

    2004-12-01

    Full Text Available The interaction of the solar wind with the ionosphere of planet Mars is studied using a three-dimensional hybrid model. Mars has only a weak intrinsic magnetic field, and consequently its ionosphere is directly affected by the solar wind. The gyroradii of the solar wind protons are in the range of several hundred kilometers and therefore comparable with the characteristic scales of the interaction region. Different boundaries emerge from the interaction of the solar wind with the continuously produced ionospheric heavy-ion plasma, which could be identified as a bow shock (BS, ion composition boundary (ICB and magnetic pile up boundary (MPB, where the latter both turn out to coincide. The simulation results regarding the shape and position of these boundaries are in good agreement with the measurements made by Phobos-2 and MGS spacecraft. It is shown that the positions of these boundaries depend essentially on the ionospheric production rate, the solar wind ram pressure, and the often unconsidered electron temperature of the ionospheric heavy ion plasma. Other consequences are rays of planetary plasma in the tail and heavy ion plasma clouds, which are stripped off from the dayside ICB region by some instability. Key words. Magnetospheric physics (solar wind interactions with unmagnetized bodies – Space plasma physics (discontinuities; numerical simulation studies

  13. Simulating lightning into the RAMS model: two case studies

    Science.gov (United States)

    Federico, Stefano; Avolio, Elenio; Petracca, Marco; Panegrossi, Giulia; Dietrich, Stefano

    2013-04-01

    In this paper we show the results of the implementation of a tailored version of a methodology already presented in the bibliography to simulate flashes into the Regional Atmospheric Modeling System (RAMS). The method gives the flash rate for each thundercloud, which is detected by a labelling algorithm applied to the output of RAMS. The flash rate is computed by assuming a plane capacitor model, which is charged by the non-inductive graupel-ice charge separation mechanism and is discharged by lightning. The method explicitly considers the charging zone and uses the geometry of the graupel field to redistribute the flashes. An important feature of the method is that it gives the position and time of occurrence of each flash, allowing for a detailed and comprehensive display of the lightning activity during the simulation period. The method is applied to two case studies occurred over the Lazio Region, in central Italy. Simulations are compared with the lightning detected by the LINET network. The cases refer to a thunderstorm characterized by an intense lightning activity (up to 2800 flashes per hour over the Lazio Region), and a moderate thunderstorm (up to 1600 flashes per hour over the same domain). The results show that the model is able to catch the main features of both storms and their relative differences. This feature is promising because the method is computationally fast and gives a tool to the forecaster to predict the lightning threat. Nevertheless there are errors in timing (O(3h)) and positioning (O(100km)) of the convection, which mirrors in timing and position errors of the lightning distribution. These model shortcomings presently limit the use of the lightning forecast; nevertheless the method can take advantages of future development of the model physics, initialization techniques, and ensemble forecast. A useful application of the method in an ensemble forecast is already suggested.

  14. Nursing Student Anxiety in Simulation Settings: A Mixed Methods Study

    Science.gov (United States)

    Cato, Mary Louise

    2013-01-01

    The use of simulation as a clinical learning activity is growing in nursing programs across the country. Using simulation, educators can provide students with a realistic patient situation using mannequins or actors as patients in a simulated environment. Students can practice multiple aspects of patient care without the risk of making mistakes…

  15. Scheduling of a computer integrated manufacturing system: A simulation study

    Directory of Open Access Journals (Sweden)

    Nadia Bhuiyan

    2011-12-01

    Full Text Available Purpose: The purpose of this paper is to study the effect of selected scheduling dispatching rules on the performance of an actual CIM system using different performance measures and to compare the results with the literature.Design/methodology/approach: To achieve this objective, a computer simulation model of the existing CIM system is developed to test the performance of different scheduling rules with respect to mean flow time, machine efficiency and total run time as performance measures.Findings: Results suggest that the system performs much better considering the machine efficiency when the initial number of parts released is maximum and the buffer size is minimum. Furthermore, considering the average flow time, the system performs much better when the selected dispatching rule is either Earliest Due Date (EDD or Shortest Process Time (SPT with buffer size of five and the initial number of parts released of eight.Research limitations/implications: In this research, some limitations are: a limited number of factors and levels were considered for the experiment set-up; however the flexibility of the model allows experimenting with additional factors and levels. In the simulation experiments of this research, three scheduling dispatching rules (First In/First Out (FIFO, EDD, SPT were used. In future research, the effect of other dispatching rules on the system performance can be compared. Some assumptions can be relaxed in future work.Practical implications: This research helps to identify the potential effect of a selected number of dispatching rules and two other factors, the number of buffers and initial number of parts released, on the performance of the existing CIM systems with different part types where the machines are the major resource constraints.Originality/value: This research is among the few to study the effect of the dispatching rules on the performance of the CIM systems with use of terminating simulation analysis. This is

  16. Studies of climate dynamics with innovative global-model simulations

    Science.gov (United States)

    Shi, Xiaoming

    Climate simulations with different degrees of idealization are essential for the development of our understanding of the climate system. Studies in this dissertation employ carefully designed global-model simulations for the goal of gaining theoretical and conceptual insights into some problems of climate dynamics. Firstly, global warming-induced changes in extreme precipitation are investigated using a global climate model with idealized geography. The precipitation changes over an idealized north-south mid-latitude mountain barrier at the western margin of an otherwise flat continent are studied. The intensity of the 40 most intense events on the western slopes increases by about ~4°C of surface warming. In contrast, the intensity of the top 40 events on the eastern mountain slopes increases at about ~6°C. This higher sensitivity is due to enhanced ascent during the eastern-slope events, which can be explained in terms of linear mountain-wave theory relating to global warming-induced changes in the upper-tropospheric static stability and the tropopause level. Dominated by different dynamical factors, changes in the intensity of extreme precipitation events over plains and oceans might differ from changes over mountains. So the response of extreme precipitation over mountains and flat areas are further compared using larger data sets of simulated extreme events over the two types of surfaces. It is found that the sensitivity of extreme precipitation to increases in global mean surface temperature is 3% per °C lower over mountains than over the oceans or the plains. The difference in sensitivity among these regions is not due to thermodynamic effects, but rather to differences between the gravity-wave dynamics governing vertical velocities over the mountains and the cyclone dynamics governing vertical motions over the oceans and plains. The strengthening of latent heating in the storms over oceans and plains leads to stronger ascent in the warming climate

  17. Improving Aviation Safety with information Visualization: A Flight Simulation Study

    Science.gov (United States)

    Aragon, Cecilia R.; Hearst, Marti

    2005-01-01

    Many aircraft accidents each year are caused by encounters with invisible airflow hazards. Recent advances in aviation sensor technology offer the potential for aircraft-based sensors that can gather large amounts of airflow velocity data in real-time. With this influx of data comes the need to study how best to present it to the pilot - a cognitively overloaded user focused on a primary task other than that of information visualization. In this paper, we present the results of a usability study of an airflow hazard visualization system that significantly reduced the crash rate among experienced helicopter pilots flying a high fidelity, aerodynamically realistic fixed-base rotorcraft flight simulator into hazardous conditions. We focus on one particular aviation application, but the results may be relevant to user interfaces in other operationally stressful environments.

  18. Socialising Health Burden Through Different Network Topologies: A Simulation Study.

    Science.gov (United States)

    Peacock, Adrian; Cheung, Anthony; Kim, Peter; Poon, Simon K

    2017-01-01

    An aging population and the expectation of premium quality health services combined with the increasing economic burden of the healthcare system requires a paradigm shift toward patient oriented healthcare. The guardian angel theory described by Szolovits [1] explores the notion of enlisting patients as primary providers of information and motivation to patients with similar clinical history through social connections. In this study, an agent based model was developed to simulate to explore how individuals are affected through their levels of intrinsic positivity. Ring, point-to-point (paired buddy), and random networks were modelled, with individuals able to send messages to each other given their levels of variables positivity and motivation. Of the 3 modelled networks it is apparent that the ring network provides the most equal, collective improvement in positivity and motivation for all users. Further study into other network topologies should be undertaken in the future.

  19. Simulation study of territory size distributions in subterranean termites.

    Science.gov (United States)

    Jeon, Wonju; Lee, Sang-Hee

    2011-06-21

    In this study, on the basis of empirical data, we have simulated the foraging tunnel patterns of two subterranean termites, Coptotermes formosanus Shiraki and Reticulitermes flavipes (Kollar), using a two-dimensional model. We have defined a territory as a convex polygon containing a tunnel pattern and explored the effects of competition among termite territory colonies on the territory size distribution in the steady state that was attained after a sufficient simulation time. In the model, territorial competition was characterized by a blocking probability P(block) that quantitatively describes the ease with which a tunnel stops its advancement when it meets another tunnel; higher P(block) values imply easier termination. In the beginning of the simulation run, N=10, 20,…,100 territory seeds, representing the founding pair, were randomly distributed on a square area. When the territory density was less (N=20), the differences in the territory size distributions for different P(block) values were small because the territories had sufficient space to grow without strong competitions. Further, when the territory density was higher (N>20), the territory sizes increased in accordance with the combinational effect of P(block) and N. In order to understand these effects better, we introduced an interference coefficient γ. We mathematically derived γ as a function of P(block) and N: γ(N,P(block))=a(N)P(block)/(P(block)+b(N)). a(N) and b(N) are functions of N/(N+c) and d/(N+c), respectively, and c and d are constants characterizing territorial competition. The γ function is applicable to characterize the territoriality of various species and increases with both the P(block) values and N; higher γ values imply higher limitations of the network growth. We used the γ function, fitted the simulation results, and determined the c and d values. In addition, we have briefly discussed the predictability of the present model by comparing it with our previous lattice model

  20. Hybrid simulation: an active power filter case study

    Directory of Open Access Journals (Sweden)

    Y. A. Garcés

    2011-10-01

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

  1. A simulation study of gel pillow heat conductance.

    Science.gov (United States)

    Friddle, Kathryn; Smith, Sandra L

    2009-10-01

    The gel-filled pillow is a device used to provide a soft surface to support and cradle an infant's head. Little is known about the thermal conductive properties of this device when used in an open crib. This simulation study evaluated the use of the Squishon 2 gel pillow in an open crib to determine the potential cooling effects on a mannequin infant. This simulation study was conducted on a thermal mannequin. A descriptive comparative repeated-measures design was employed. A thermal mannequin with the head placed on the gel pillow was used. The energy required to keep the mannequin head at 37 degrees C in 4 conditions was measured. The 4 conditions were as follows: (1) lying in an open crib on a standard mattress (baseline), (2) lying on the gel pillow with the disposable cover from the manufacturer, (3) the head wearing a cap and lying on the gel pillow, and (4) the head without the hat lying on the gel pillow with an insulated cover over the pillow. Univariate analysis of variance (ANOVA) revealed significant differences in energy required to maintain the mannequin head at 37 degrees C among the 4 conditions (F3 = 283.23, P = .0001). The hat on head condition was found to decrease energy utilization by an average of 6.36 kcal/d when compared with the head on mattress condition (P = .0001). Extrapolation of energy to maintain mannequin head warmth into potential kilocalories utilized revealed that a potential increase in kilocalories needed to maintain thermoneutrality would be needed. The most effective way of conserving heat was in the hat on the mannequin head while lying on a gel pillow condition. The use of a gel pillow without a hat or an insulated barrier caused an increase in energy requirements and kilocalorie usage in this mannequin model. The results of this simulation study suggest that use of the gel pillow outside of a thermally controlled environment and in an open crib environment may increase energy use to maintain thermoneutrality. The Squishon

  2. A larval dispersion study using lagrangian simulation of particles

    Directory of Open Access Journals (Sweden)

    Laura Rodríguez Díaz

    2014-06-01

    Full Text Available The continuous displacement of water allows stabilize the temperature and also distributes nutrients and plankton in the ocean and seas permitting the development of organisms and the transfers of larvae from the spawning areas to the habitat where adult fishes can be found. The area of study covers The North Atlantic Ocean so the principal aim of the study is analyze if released particles at the Florida Strait could cross the North Atlantic Ocean and reach the European shelf. To test this, it has simulated Lagrangian trajectories for different numbers of particles or "larvae" with a passive behavior (fixing at a depth of dispersion. It has analyzed the dispersion of those particles by using the data of the components U, V and W from the speed of currents provided by the database SODA which uses an ocean model based on Geophysical Fluid Dynamics Laboratory MOM2 and data profiles from World Ocean Atlas-94 and from Geosat, ERS-1 and TOPEX/Poseidon satellites. Considering the dispersive nature of the ocean, the simulations were performed by releasing many particles (typically of the order of several thousand and it was also necessary to perform an interpolation process in time and space so that the position of the particles could evolve. The simulations have been run with 5,000 particles and it has been considered a biological parameter (planktonic larval duration, PLD that represents the length of larval life. At this study it has been used PLD for a specific starfish larva (Sclerasterias tanneri larvae that can be found at the Gulf of Mexico at different locations. Particles were released in October at the most oceanward location of the Gulf of Mexico close to the Florida Strait where Sclerasterias tanneri larvae can be found. Those particles have been tracked for 660 days (660 days is the PLD of Sclerasterias tanneri larvae recording their position every 15 days. That it has done for a period of more than 100 years (1901-2010. The period (1901

  3. Composite pulses for RF phase encoded MRI: A simulation study.

    Science.gov (United States)

    Salajeghe, Somaie; Babyn, Paul; Sarty, Gordon E

    2017-02-01

    In B1 encoded MRI, a realistic non-linear phase RF encoding coil will generate an inhomogeneous B1 field that leads to spatially dependent flip angles. The non-linearity of the B1 phase gradient can be compensated for in the reconstruction, but B1 inhomogeneity remains a problem. The effect of B1 inhomogeneity on tip angles for conventional, B0 encoded MRI, may be minimized using composite pulses. The objective of this study was to explore the feasibility of using composite pulses with non-linear RF phase encoding coils and to identify the most appropriate composite pulse scheme. RF encoded signals were simulated via the Bloch equation for various symmetric, asymmetric and antisymmetric composite pulses. The simulated signals were reconstructed using a constrained least squares method. Root mean square reconstruction errors varied from 6% (for an asymmetric composite pulse) to 9.7% (for an antisymmetric composite pulse). An asymmetric composite pulse scheme created images with fewer artifacts than other composite pulse schemes in inhomogeneous B0 and B1 fields making it the best choice for decreasing the effects of spatially varying flip angles. This is contrary to the conclusion that antisymmetric composite pulses are the best ones to use for spin echo sequences in conventional, B0 encoded, MRI. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  4. Sphericity estimation bias for repeated measures designs in simulation studies.

    Science.gov (United States)

    Bono, Roser; Arnau, Jaume; Blanca, María J; Alarcón, Rafael

    2016-12-01

    In this study, we explored the accuracy of sphericity estimation and analyzed how the sphericity of covariance matrices may be affected when the latter are derived from simulated data. We analyzed the consequences that normal and nonnormal data generated from an unstructured population covariance matrix-with low (ε = .57) and high (ε = .75) sphericity-can have on the sphericity of the matrix that is fitted to these data. To this end, data were generated for four types of distributions (normal, slightly skewed, moderately skewed, and severely skewed or log-normal), four sample sizes (very small, small, medium, and large), and four values of the within-subjects factor (K = 4, 6, 8, and 10). Normal data were generated using the Cholesky decomposition of the correlation matrix, whereas the Vale-Maurelli method was used to generate nonnormal data. The results indicate the extent to which sphericity is altered by recalculating the covariance matrix on the basis of simulated data. We concluded that bias is greater with spherical covariance matrices, nonnormal distributions, and small sample sizes, and that it increases in line with the value of K. An interaction was also observed between sample size and K: With very small samples, the observed bias was greater as the value of K increased.

  5. Simulation studies of nucleation of ferroelectric polarization reversal.

    Energy Technology Data Exchange (ETDEWEB)

    Brennecka, Geoffrey L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Winchester, Benjamin Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-08-01

    Electric field-induced reversal of spontaneous polarization is the defining characteristic of a ferroelectric material, but the process(es) and mechanism(s) associated with the initial nucleation of reverse-polarity domains are poorly understood. This report describes studies carried out using phase field modeling of LiTaO3, a relatively simple prototype ferroelectric material, in order to explore the effects of either mechanical deformation or optically-induced free charges on nucleation and resulting domain configuration during field-induced polarization reversal. Conditions were selected to approximate as closely as feasible those of accompanying experimental work in order to provide not only support for the experimental work but also ensure that additional experimental validation of the simulations could be carried out in the future. Phase field simulations strongly support surface mechanical damage/deformation as effective for dramatically reducing the overall coercive field (Ec) via local field enhancements. Further, optically-nucleated polarization reversal appears to occur via stabilization of latent nuclei via the charge screening effects of free charges.

  6. Simulation study of dielectrophoretic assembly of nanowire between electrode pairs

    Science.gov (United States)

    Tao, Quan; Lan, Fei; Jiang, Minlin; Wei, Fanan; Li, Guangyong

    2015-07-01

    Dielectrophoresis (DEP) of rod-shaped nanostructures is attractive because of its exceptional capability to fabricate nanowire-based electronic devices. This efficient manipulation method, however, has a common side effect of assembling a certain number of nanowires at undesired positions. It is therefore essential to understand the underlying physics of DEP of nanowires in order to better guide the assembly. In this work, we propose theoretical methods to characterize the dielectrophoretic force and torque as well as the hydrodynamic drag force and torque on the nanowire (typical length: 10 μm). The trajectory of the nanowire is then simulated based on rigid body dynamics. The nanowire is predicted to either bridge the electrodes or attach on the surface of one electrode. A neighborhood in which the nanowire is more likely to bridge electrodes is found, which is conducive to successful assembly. The simulation study in this work provides us not only a better understanding of the underlying physics but also practical guidance on nanowire assembly by DEP.

  7. Simulation studies for the ATLAS upgrade Strip tracker

    CERN Document Server

    Wang, Jike; The ATLAS collaboration

    2017-01-01

    ATLAS is making extensive efforts towards preparing a detector upgrade for the High luminosity operations of the LHC (HL-LHC), which will commence operation in ~10 years. The current ATLAS Inner Detector will be replaced by a all-silicon tracker (comprising an inner Pixel tracker and outer Strip tracker). The software currently used for the new silicon tracker is broadly inherited from that used for the LHC Run 1 and 2, but many new developments have been made to better fulfil the future detector and operation requirements. One aspect in particular which will be highlighted is the simulation software for the Strip tracker. The available geometry description software (including the detailed description for all the sensitive elements, the services, etc.) did not allow for accurate modeling of the planned detector design. A range of sensors/layouts for the Strip tracker are being considered and must be studied in detailed simulations in order to assess the performance and ascertain that requirements are met. For...

  8. Simulation Studies of Satellite Laser CO2 Mission Concepts

    Science.gov (United States)

    Kawa, Stephan Randy; Mao, J.; Abshire, J. B.; Collatz, G. J.; Sun X.; Weaver, C. J.

    2011-01-01

    Results of mission simulation studies are presented for a laser-based atmospheric CO2 sounder. The simulations are based on real-time carbon cycle process modeling and data analysis. The mission concept corresponds to ASCENDS as recommended by the US National Academy of Sciences Decadal Survey. Compared to passive sensors, active (lidar) sensing of CO2 from space has several potentially significant advantages that hold promise to advance CO2 measurement capability in the next decade. Although the precision and accuracy requirements remain at unprecedented levels of stringency, analysis of possible instrument technology indicates that such sensors are more than feasible. Radiative transfer model calculations, an instrument model with representative errors, and a simple retrieval approach complete the cycle from "nature" run to "pseudodata" CO2. Several mission and instrument configuration options are examined, and the sensitivity to key design variables is shown. Examples are also shown of how the resulting pseudo-measurements might be used to address key carbon cycle science questions.

  9. Integration of a driving simulator and a traffic simulator case study: Exploring drivers' behavior in response to variable message signs

    Directory of Open Access Journals (Sweden)

    Mansoureh Jeihani

    2017-12-01

    Full Text Available For the first time, a driving simulator has been integrated with a traffic simulator at the network level to allow subjects to drive in a fairly realistic environment with a realistic traffic flow and density. A 10 mi2 (25 km2 network was developed in a driving simulator and then exported to a traffic simulator. About 30 subjects drove the simulator under different traffic and driving conditions and variable message sign (VMS information, both with and without integration. Route guidance was available for the subjects. The challenges of the integration process are explained and its advantages investigated. The study concluded that traffic density, VMS reliability and compliance behavior are higher when driving and traffic simulators are integrated. To find factors affecting route diversion, researchers applied a binary logistic regression model. The results indicated that the original chosen route, displayed VMS information, subjects' attitude toward VMS information helpfulness, and their level of exposure to VMS affect route diversion. In addition, a multinomial logistic regression model was employed to investigate important factors in route choice. The results revealed that there is a significant correlation with driver route choice behavior and their actual travel time, the need for GPS, VMS exposure and also the designed scenarios. It should be noted that the paper was peer-reviewed by TRB and presented at the TRB Annual Meeting, Washington, D.C., January 2016. Keywords: Integration, Variable message sign, Compliance behavior, Driving simulator, Traffic simulator, Discrete choice analysis

  10. White book Escrime. Climatic simulation studies; Livre blanc Escrime. Etude des simulations climatiques

    Energy Technology Data Exchange (ETDEWEB)

    Terray, L. [CERFACS, 31 - Toulouse (France); Braconnot, P. [Institut Pierre-Simon Laplace IPSL/LSCE, CEA-Orme des Merisiers, 91 - Gif-sur-Yvette (France)

    2007-01-15

    The ESCRIME project aims to manage the analysis realized on the climatic simulations on the framework of the fourth report of the GIEC (group of intergovernmental experts on the climate evolution), in particularly the simulations based on french models. This white book is constituted by 8 chapters: the global scenario, the climatic sensibility, the variation modes, the regionalization and the extremes, the hydrological cycle, the polar regions and the cryo-sphere, the carbon cycle, detection and attributions. (A.L.B.)

  11. Simulation Studies on Harnessing of Artificial Ecosystems in Space Colonies

    Science.gov (United States)

    Miyajima, Hiroyuki

    Space Colonies are an artificial habitation built in space, an idea first proposed by Gerard K. O'Neill in 1969. He suggested they be placed at Lagrange points which are points in space that balance out the gravitational attraction of the Earth and Moon. There are three types of space colonies proposed: Bernard, Cylinder, and Stanford Torus. The cylinder type, designed by Gerard K. O'Neill, is the most popular in concept at 6 km diameter and 30 km length, corresponding to about 845 cubic km, ten thousand people would potentially be able to reside these. The habitation area would be rotated to generate a quasi-gravitation by centrifugal force. It would be rotated at 0.55 rpm to generate a gravitation equivalent to that of the earth. In the space colony, there would be six areas axially, consisting of flooring and windows alternately. Mobile mirrors would be located outside the windows to reflect sun light toward the habitation areas and generate day, night, and seasons within the space colony. Thus an artificial ecosystem would be created allowing people live in much the same way as they do on the earth. According to my former research on micro ecosystems, it is very difficult to keep the environment balanced at all points due to the large volume of the habitation area and the thermal input of the mobile mirrors. It is predicted that there will be differences in the environment at each point of the cylinder due to the mirror angle. Although controlling the whole artificial ecosystem balance is important, local environment control at each point is also important for people to live and work comfortably. Therefore, it is needed to develop simulation models which can study the whole ecosystem as well as local environments at each point at the same time. This model has to be able to simulate dynamics of the whole system as well as the local environments. In this study, I have developed a new model to simulate the whole and local dynamics in a space colony by using a cell

  12. Theory, modelling and simulation in origins of life studies.

    Science.gov (United States)

    Coveney, Peter V; Swadling, Jacob B; Wattis, Jonathan A D; Greenwell, H Christopher

    2012-08-21

    Origins of life studies represent an exciting and highly multidisciplinary research field. In this review we focus on the contributions made by theory, modelling and simulation to addressing fundamental issues in the domain and the advances these approaches have helped to make in the field. Theoretical approaches will continue to make a major impact at the "systems chemistry" level based on the analysis of the remarkable properties of nonlinear catalytic chemical reaction networks, which arise due to the auto-catalytic and cross-catalytic nature of so many of the putative processes associated with self-replication and self-reproduction. In this way, we describe inter alia nonlinear kinetic models of RNA replication within a primordial Darwinian soup, the origins of homochirality and homochiral polymerization. We then discuss state-of-the-art computationally-based molecular modelling techniques that are currently being deployed to investigate various scenarios relevant to the origins of life.

  13. A simulation based case study for control of DSTATCOM.

    Science.gov (United States)

    Kumar, Pradeep; Kumar, Niranjan; Akella, A K

    2014-05-01

    This paper presents a distribution static compensator (DSTATCOM) for power quality improvements in terms of harmonics and power factor correction in a three-phase four-wire distribution system. The DSTATCOM is implemented with PWM current controlled six-leg voltage source converter (VSC) and the switching patterns are generated through a novel synchronous reference frame controller (SRFC). The insulated gate bipolar transistor (IGBT) based VSC is supported by a capacitor and is controlled for the required compensation of the load current. The DSTATCOM is connected to the power system feeding nonlinear loads. Nonlinear loads include either current-source type or voltage-source type. Harmonic spectrum of the source current is compared in between without DSTATCOM and with DSTATCOM by considering both types of nonlinear loads. The SRFC based DSTATCOM system is validated through extensive simulation for diode-rectifier and unbalanced R-L loads with a case study. © 2013 ISA Published by ISA All rights reserved.

  14. Performance simulation studies for the ALICE TPC GEM upgrade

    Science.gov (United States)

    Ljunggren, M.; Alice Collaboration

    2016-07-01

    To be able to exploit the anticipated interaction rate of 50 kHz in Pb-Pb collisions during run 3 of the LHC (beyond 2019), the ALICE TPC will be upgraded to allow continuous readout. As this is not possible with the current Multi Wire Proportional Chamber (MWPC) based amplification, the readout will be replaced with Gas Electron Multiplier (GEM) readout chambers that can suppress 99% of the ion back flow. The space charge of the remaining 1% ion back flow, however, will cause significant distortions to the measured tracks of order cm. Simulation studies to characterize the distortions and test correction strategies have been performed, which show that the intrinsic momentum resolution, without these distortions, can be recovered.

  15. A simulation study of the critical ionization velocity process

    Science.gov (United States)

    Machida, S.; Goertz, C. K.

    1986-01-01

    The critical ionization velocity process is studied by first investigating a coupled system of equations describing the production of several ion species and electrons by impact ionization, their collisions with neutrals, and the heating of electrons. Analytic relations derived from this were tested with the help of a particle simulation, including collisional processes between neutrals and plasma particles. It was found that resistive heating of electrons plays an important role when the density of the neutrals is high, and that electron heating due to lower hybrid waves is significant when the neutral density is low. In both cases, the control of the plasma production rate by the ratio of the beam velocity to the critical velocity was verified.

  16. Simulation Study of Traffic Accidents in Bidirectional Traffic Models

    Science.gov (United States)

    Moussa, Najem

    Conditions for the occurrence of bidirectional collisions are developed based on the Simon-Gutowitz bidirectional traffic model. Three types of dangerous situations can occur in this model. We analyze those corresponding to head-on collision; rear-end collision and lane-changing collision. Using Monte Carlo simulations, we compute the probability of the occurrence of these collisions for different values of the oncoming cars' density. It is found that the risk of collisions is important when the density of cars in one lane is small and that of the other lane is high enough. The influence of different proportions of heavy vehicles is also studied. We found that heavy vehicles cause an important reduction of traffic flow on the home lane and provoke an increase of the risk of car accidents.

  17. Degeneracy and long-range correlation: A simulation study

    Directory of Open Access Journals (Sweden)

    Marmelat Vivien

    2011-12-01

    Full Text Available We present in this paper a simulation study that aimed at evidencing a causal relationship between degeneracy and long-range correlations. Long-range correlations represent a very specific form of fluctuations that have been evidenced in the outcomes time series produced by a number of natural systems. Long-range correlations are supposed to sign the complexity, adaptability and flexibility of the system. Degeneracy is defined as the ability of elements that are structurally different to perform the same function, and is presented as a key feature for explaining the robustness of complex systems. We propose a model able to generate long-range correlated series, and including a parameter that account for degeneracy. Results show that a decrease in degeneracy tends to reduce the strength of long-range correlation in the series produced by the model.

  18. Cognitive distance, absorptive capacity and group rationality: a simulation study.

    Directory of Open Access Journals (Sweden)

    Petru Lucian Curşeu

    Full Text Available We report the results of a simulation study in which we explore the joint effect of group absorptive capacity (as the average individual rationality of the group members and cognitive distance (as the distance between the most rational group member and the rest of the group on the emergence of collective rationality in groups. We start from empirical results reported in the literature on group rationality as collective group level competence and use data on real-life groups of four and five to validate a mathematical model. We then use this mathematical model to predict group level scores from a variety of possible group configurations (varying both in cognitive distance and average individual rationality. Our results show that both group competence and cognitive distance are necessary conditions for emergent group rationality. Group configurations, in which the groups become more rational than the most rational group member, are groups scoring low on cognitive distance and scoring high on absorptive capacity.

  19. Monte Carlo simulations and benchmark studies at CERN's accelerator chain

    CERN Document Server

    AUTHOR|(CDS)2083190; Brugger, Markus

    2016-01-01

    Mixed particle and energy radiation fields present at the Large Hadron Collider (LHC) and its accelerator chain are responsible for failures on electronic devices located in the vicinity of the accelerator beam lines. These radiation effects on electronics and, more generally, the overall radiation damage issues have a direct impact on component and system lifetimes, as well as on maintenance requirements and radiation exposure to personnel who have to intervene and fix existing faults. The radiation environments and respective radiation damage issues along the CERN’s accelerator chain were studied in the framework of the CERN Radiation to Electronics (R2E) project and are hereby presented. The important interplay between Monte Carlo simulations and radiation monitoring is also highlighted.

  20. A simulation study of three methods for detecting disease clusters

    Directory of Open Access Journals (Sweden)

    Samuelsen Sven O

    2006-04-01

    Full Text Available Abstract Background Cluster detection is an important part of spatial epidemiology because it can help identifying environmental factors associated with disease and thus guide investigation of the aetiology of diseases. In this article we study three methods suitable for detecting local spatial clusters: (1 a spatial scan statistic (SaTScan, (2 generalized additive models (GAM and (3 Bayesian disease mapping (BYM. We conducted a simulation study to compare the methods. Seven geographic clusters with different shapes were initially chosen as high-risk areas. Different scenarios for the magnitude of the relative risk of these areas as compared to the normal risk areas were considered. For each scenario the performance of the methods were assessed in terms of the sensitivity, specificity, and percentage correctly classified for each cluster. Results The performance depends on the relative risk, but all methods are in general suitable for identifying clusters with a relative risk larger than 1.5. However, it is difficult to detect clusters with lower relative risks. The GAM approach had the highest sensitivity, but relatively low specificity leading to an overestimation of the cluster area. Both the BYM and the SaTScan methods work well. Clusters with irregular shapes are more difficult to detect than more circular clusters. Conclusion Based on our simulations we conclude that the methods differ in their ability to detect spatial clusters. Different aspects should be considered for appropriate choice of method such as size and shape of the assumed spatial clusters and the relative importance of sensitivity and specificity. In general, the BYM method seems preferable for local cluster detection with relatively high relative risks whereas the SaTScan method appears preferable for lower relative risks. The GAM method needs to be tuned (using cross-validation to get satisfactory results.

  1. Numerical Simulation Study of the Sanchiao Fault Earthquake Scenarios

    Science.gov (United States)

    Wang, Yi-Min; Lee, Shiann-Jong

    2015-04-01

    Sanchiao fault is a western boundary fault of the Taipei basin located in northern Taiwan, close to the densely populated Taipei metropolitan area. Recent study indicated that there is about 40 km of the fault trace extended to the marine area offshore northern Taiwan. Combining the marine and terrestrial parts, the total fault length of Sanchiao fault could be nearly 70 kilometers which implies that this fault has potential to produce a big earthquake. In this study, we analyze several Sanchiao fault earthquake scenarios based on the recipe for predicting strong ground motion. The characterized source parameters include fault length, rupture area, seismic moment, asperity, and slip pattern on the fault plane. According to the assumption of the characterized source model, Sanchiao fault has been inferred to have the potential to produce an earthquake with moment magnitude (Mw) larger than 7.0. Three-dimensional seismic simulation results based upon spectral-element method (SEM) indicate that peak ground acceleration (PGA) is significantly stronger along the fault trace. The basin effect also plays an important role when wave propagates in the Taipei basin which cause seismic wave amplified and prolong the shaking for a very long time. Among all rupture scenarios, the rupture propagated from north to south is the most serious one. Owing to the rupture directivity as well as the basin effects, large PGA (>1g) was observed in the Taipei basin, especially in the northwest side. The results of these scenario earthquake simulations will provide important physically-based numerical data for earthquake mitigation and seismic hazard assessment.

  2. A study on the shielding element using Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Jeong [Dept. of Radiology, Konkuk University Medical Center, Seoul (Korea, Republic of); Shim, Jae Goo [Dept. of Radiologic Technology, Daegu Health College, Daegu (Korea, Republic of)

    2017-06-15

    In this research, we simulated the elementary star shielding ability using Monte Carlo simulation to apply medical radiation shielding sheet which can replace existing lead. In the selection of elements, mainly elements and metal elements having a large atomic number, which are known to have high shielding performance, recently, various composite materials have improved shielding performance, so that weight reduction, processability, In consideration of activity etc., 21 elements were selected. The simulation tools were utilized Monte Carlo method. As a result of simulating the shielding performance by each element, it was estimated that the shielding ratio is the highest at 98.82% and 98.44% for tungsten and gold.

  3. Ankle fractures: When can I drive, doctor? A simulation study.

    Science.gov (United States)

    Yousri, Taher; Jackson, Mark

    2015-02-01

    Traumatic ankle fractures are common injuries. Following injury, patients ask their doctor 'when can I drive doctor?' The ability to safely drive depends on several variables including reaction time, force, range of movement and pain. Return of the braking force is essential for return to driving and to our knowledge has not been addressed previously in the literature. The aim of this study is to pilot a sample of patients with ankle fractures for the return of their normal power and visual reaction time following injury using a simulator (DTS: Drive Test Station). Normal parameters were defined by the patient's contra-lateral non-injured limb. After confirming fracture union, 12 drivers with an isolated right ankle fracture were recruited 7.8 days after coming out of plaster (0-21 days). DTS was used to examine patients' ability to apply a braking force of 35 kg, representing the amount of force required to do an emergency stop at 70 mph. Visual reaction time was tested to assess patients' cognitive function. Results showed the average maximum brake pedal force to be 34.4 kg (range: 32-35 kg). Paired sample t-test for the total visual reaction time and visual pathway reaction time showed the p-value>0.05 indicating no statistical difference between the injured limb and non-injured control side at the time of the examination. In conclusion, the DTS can be used to simulate an emergency stop to assess the motor power and cognitive function (visual reaction time) in case of right ankle fractures as this can give the patient an idea regarding their ability to apply brake force and the return of their visual reaction time. It is a practical assessment tool that could be used in fracture clinic setting. We still reserve our ability to advise patients to return to driving as this could bear significant medicolegal responsibility. Copyright © 2014. Published by Elsevier Ltd.

  4. Physics validation studies for muon collider detector background simulations

    Energy Technology Data Exchange (ETDEWEB)

    Morris, Aaron Owen; /Northern Illinois U.

    2011-07-01

    Within the broad discipline of physics, the study of the fundamental forces of nature and the most basic constituents of the universe belongs to the field of particle physics. While frequently referred to as 'high-energy physics,' or by the acronym 'HEP,' particle physics is not driven just by the quest for ever-greater energies in particle accelerators. Rather, particle physics is seen as having three distinct areas of focus: the cosmic, intensity, and energy frontiers. These three frontiers all provide different, but complementary, views of the basic building blocks of the universe. Currently, the energy frontier is the realm of hadron colliders like the Tevatron at Fermi National Accelerator Laboratory (Fermilab) or the Large Hadron Collider (LHC) at CERN. While the LHC is expected to be adequate for explorations up to 14 TeV for the next decade, the long development lead time for modern colliders necessitates research and development efforts in the present for the next generation of colliders. This paper focuses on one such next-generation machine: a muon collider. Specifically, this paper focuses on Monte Carlo simulations of beam-induced backgrounds vis-a-vis detector region contamination. Initial validation studies of a few muon collider physics background processes using G4beamline have been undertaken and results presented. While these investigations have revealed a number of hurdles to getting G4beamline up to the level of more established simulation suites, such as MARS, the close communication between us, as users, and the G4beamline developer, Tom Roberts, has allowed for rapid implementation of user-desired features. The main example of user-desired feature implementation, as it applies to this project, is Bethe-Heitler muon production. Regarding the neutron interaction issues, we continue to study the specifics of how GEANT4 implements nuclear interactions. The GEANT4 collaboration has been contacted regarding the minor

  5. Human thermohomeostasis onboard ''Mir'' and in simulated microgravity studies

    Science.gov (United States)

    Polyakov, V. V.; Lacota, N. G.; Gundel, A.

    2001-08-01

    Significant changes of thermogomeostatic parameters was obtained by thermotopometric method using the techniques simulate of microgravity effects: bed rest, pressurized isolation, suit immersion (SI). However, each of ground models made rectal temperature (T) trend downward. The autothermometric study (24 and 12 sessions, 2-13 th and 6- 174 th flight days) was carried out onboard "Mir" by two flight engineers who had preliminary tested at SI (1-2 days). Studies of German investigators onboard "Mir" confirmed: rectal T must be higher in space flight as compared to the normal environment (n=4). Comparative studies suggest that microgravity is a key factor for the human body surface T raise and abolishment of the external/internal T-gradient. T-homeostasis was not really changing during missions and could be regarded as acute effect of microgravity. After delineation of changes in body surface T — by Carnot's thermodynamic law — rectal T raise should have been anticipated. Facts pointing to the excess entropy of human body must not be passed over.

  6. Conditions simulating lymphoma in children - a lymphographic study

    Energy Technology Data Exchange (ETDEWEB)

    Lanning, P.; Lanning, M.; Suramo, I.

    1987-08-01

    The lymphographic appearance of lymphoma may be simulated by a variety of other diseases, both malignant and benign, including metastases, lymphangiomatosis, sarcoidosis and lymphadenitis. In addition, non-specific reactive changes of the lymph nodes are common in lymphography of children sometimes simulating lymphoma.

  7. Salt Effect on Osmotic Pressure of Polyelectrolyte Solutions: Simulation Study

    Directory of Open Access Journals (Sweden)

    Jan-Michael Y. Carrillo

    2014-07-01

    Full Text Available Abstract: We present results of the hybrid Monte Carlo/molecular dynamics simulations of the osmotic pressure of salt solutions of polyelectrolytes. In our simulations, we used a coarse-grained representation of polyelectrolyte chains, counterions and salt ions. During simulation runs, we alternate Monte Carlo and molecular dynamics simulation steps. Monte Carlo steps were used to perform small ion exchange between simulation box containing salt ions (salt reservoir and simulation box with polyelectrolyte chains, counterions and salt ions (polyelectrolyte solution. This allowed us to model Donnan equilibrium and partitioning of salt and counterions across membrane impermeable to polyelectrolyte chains. Our simulations have shown that the main contribution to the system osmotic pressure is due to salt ions and osmotically active counterions. The fraction of the condensed (osmotically inactive counterions first increases with decreases in the solution ionic strength then it saturates. The reduced value of the system osmotic coefficient is a universal function of the ratio of the concentration of osmotically active counterions and salt concentration in salt reservoir. Simulation results are in a very good agreement with osmotic pressure measurements in sodium polystyrene sulfonate, DNA, polyacrylic acid, sodium polyanetholesulfonic acid, polyvinylbenzoic acid, and polydiallyldimethylammonium chloride solutions.

  8. Evaluating best educational practices, student satisfaction, and self-confidence in simulation: A descriptive study.

    Science.gov (United States)

    Zapko, Karen A; Ferranto, Mary Lou Gemma; Blasiman, Rachael; Shelestak, Debra

    2018-01-01

    The National League for Nursing (NLN) has endorsed simulation as a necessary teaching approach to prepare students for the demanding role of professional nursing. Questions arise about the suitability of simulation experiences to educate students. Empirical support for the effect of simulation on patient outcomes is sparse. Most studies on simulation report only anecdotal results rather than data obtained using evaluative tools. The aim of this study was to examine student perception of best educational practices in simulation and to evaluate their satisfaction and self-confidence in simulation. This study was a descriptive study designed to explore students' perceptions of the simulation experience over a two-year period. Using the Jeffries framework, a Simulation Day was designed consisting of serial patient simulations using high and medium fidelity simulators and live patient actors. The setting for the study was a regional campus of a large Midwestern Research 2 university. The convenience sample consisted of 199 participants and included sophomore, junior, and senior nursing students enrolled in the baccalaureate nursing program. The Simulation Days consisted of serial patient simulations using high and medium fidelity simulators and live patient actors. Participants rotated through four scenarios that corresponded to their level in the nursing program. Data was collected in two consecutive years. Participants completed both the Educational Practices Questionnaire (Student Version) and the Student Satisfaction and Self-Confidence in Learning Scale. Results provide strong support for using serial simulation as a learning tool. Students were satisfied with the experience, felt confident in their performance, and felt the simulations were based on sound educational practices and were important for learning. Serial simulations and having students experience simulations more than once in consecutive years is a valuable method of clinical instruction. When

  9. The cerebellum in action: a simulation and robotics study.

    Science.gov (United States)

    Hofstötter, Constanze; Mintz, Matti; Verschure, Paul F M J

    2002-10-01

    The control or prediction of the precise timing of events are central aspects of the many tasks assigned to the cerebellum. Despite much detailed knowledge of its physiology and anatomy, it remains unclear how the cerebellar circuitry can achieve such an adaptive timing function. We present a computational model pursuing this question for one extensively studied type of cerebellar-mediated learning: the classical conditioning of discrete motor responses. This model combines multiple current assumptions on the function of the cerebellar circuitry and was used to investigate whether plasticity in the cerebellar cortex alone can mediate adaptive conditioned response timing. In particular, we studied the effect of changes in the strength of the synapses formed between parallel fibres and Purkinje cells under the control of a negative feedback loop formed between inferior olive, cerebellar cortex and cerebellar deep nuclei. The learning performance of the model was evaluated at the circuit level in simulated conditioning experiments as well as at the behavioural level using a mobile robot. We demonstrate that the model supports adaptively timed responses under real-world conditions. Thus, in contrast to many other models that have focused on cerebellar-mediated conditioning, we investigated whether and how the suggested underlying mechanisms could give rise to behavioural phenomena.

  10. Performance simulation studies for the ALICE TPC GEM upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Ljunggren, M., E-mail: martin.ljunggren@hep.lu.se

    2016-07-11

    To be able to exploit the anticipated interaction rate of 50 kHz in Pb–Pb collisions during run 3 of the LHC (beyond 2019), the ALICE TPC will be upgraded to allow continuous readout. As this is not possible with the current Multi Wire Proportional Chamber (MWPC) based amplification, the readout will be replaced with Gas Electron Multiplier (GEM) readout chambers that can suppress ~ 99% of the ion back flow. The space charge of the remaining 1% ion back flow, however, will cause significant distortions to the measured tracks of order cm. Simulation studies to characterize the distortions and test correction strategies have been performed, which show that the intrinsic momentum resolution, without these distortions, can be recovered. - Highlights: • The ALICE experiment is going to upgrade its detectors to accommodate a collision frequency of 50 kHz. • The Time Projection Chamber (TPC), which is the main tracking detector of the experiment, needs to be upgraded to allow continuous readout. • Continuous readout means that a gating grid can no longer be used to prevent positive ions from the amplification stage to reach the drift volume of the TPC (ion back flow). • In this paper, studies are presented that show that it is possible to correct for the space pointdistortions caused by the accumulated space charge from the ion back flow.

  11. Hydrotropic Solubilization by Urea Derivatives: A Molecular Dynamics Simulation Study

    Directory of Open Access Journals (Sweden)

    Yong Cui

    2013-01-01

    Full Text Available Hydrotropy is a phenomenon where the presence of a large quantity of one solute enhances the solubility of another solute. The mechanism of this phenomenon remains a topic of debate. This study employed molecular dynamics simulation to investigate the hydrotropic mechanism of a series of urea derivatives, that is, urea (UR, methylurea (MU, ethylurea (EU, and butylurea (BU. A poorly water-soluble compound, nifedipine (NF, was used as the model solute that was solubilized. Structural, dynamic, and energetic changes upon equilibration were analyzed to supply insights to the solubilization mechanism. The study demonstrated that NF and urea derivatives underwent significant nonstoichiometric molecular aggregation in the aqueous solution, a result consistent with the self-aggregation of urea derivatives under the same conditions. The analysis of hydrogen bonding and energy changes revealed that the aggregation was driven by the partial restoration of normal water structure. The energetic data also suggested that the promoted solubilization of NF is favored in the presence of urea derivatives. While the solutes aggregated to a varying degree, the systems were still in single-phase liquid state as attested by their active dynamics.

  12. Calibration of simulated rainfall characteristics for the study of soil erosion on agricultural land

    NARCIS (Netherlands)

    Ries, J.B.; Seeger, K.M.; Iserloh, I.; Wistorf, S.; Fister, W.

    2009-01-01

    Rainfall simulation is a widely used method for soil erosion studies on agricultural land. Major problem of this experimental research method is the comparability between different simulators due to differences in simulated rainfall. Therefore the purpose of this study is to characterize the

  13. Comparative study of the effectiveness of three learning environments: Hyper-realistic virtual simulations, traditional schematic simulations and traditional laboratory

    Directory of Open Access Journals (Sweden)

    Maria Isabel Suero

    2011-10-01

    Full Text Available This study compared the educational effects of computer simulations developed in a hyper-realistic virtual environment with the educational effects of either traditional schematic simulations or a traditional optics laboratory. The virtual environment was constructed on the basis of Java applets complemented with a photorealistic visual output. This new virtual environment concept, which we call hyper-realistic, transcends basic schematic simulation; it provides the user with a more realistic perception of a physical phenomenon being simulated. We compared the learning achievements of three equivalent, homogeneous groups of undergraduates—an experimental group who used only the hyper-realistic virtual laboratory, a first control group who used a schematic simulation, and a second control group who used the traditional laboratory. The three groups received the same theoretical preparation and carried out equivalent practicals in their respective learning environments. The topic chosen for the experiment was optical aberrations. An analysis of variance applied to the data of the study demonstrated a statistically significant difference (p value <0.05 between the three groups. The learning achievements attained by the group using the hyper-realistic virtual environment were 6.1 percentage points higher than those for the group using the traditional schematic simulations and 9.5 percentage points higher than those for the group using the traditional laboratory.

  14. Simulation study of granular compaction dynamics under vertical tapping.

    Science.gov (United States)

    Arsenović, D; Vrhovac, S B; Jaksić, Z M; Budinski-Petković, Lj; Belić, A

    2006-12-01

    We study, by numerical simulation, the compaction dynamics of frictional hard disks in two dimensions, subjected to vertical shaking. Shaking is modeled by a series of vertical expansion of the disk packing, followed by dynamical recompression of the assembly under the action of gravity. The second phase of the shake cycle is based on an efficient event-driven molecular-dynamics algorithm. We analyze the compaction dynamics for various values of friction coefficient and coefficient of normal restitution. We find that the time evolution of the density is described by rho(t)=rho{infinity}-DeltarhoE{alpha}[-(ttau){alpha}], where E{alpha} denotes the Mittag-Leffler function of order 0

  15. Epidemiological impact of a syphilis vaccine: a simulation study.

    Science.gov (United States)

    Champredon, D; Cameron, C E; Smieja, M; Dushoff, J

    2016-11-01

    Despite the availability of inexpensive antimicrobial treatment, syphilis remains prevalent worldwide, affecting millions of individuals. Furthermore, syphilis infection is suspected of increasing both susceptibility to, and tendency to transmit, HIV. Development of a syphilis vaccine would be a potentially promising step towards control, but the value of dedicating resources to vaccine development should be evaluated in the context of the anticipated benefits. Here, we use a detailed mathematical model to explore the potential impact of rolling out a hypothetical syphilis vaccine on morbidity from both syphilis and HIV and compare it to the impact of expanded 'screen and treat' programmes using existing treatments. Our results suggest that an efficacious vaccine has the potential to sharply reduce syphilis prevalence under a wide range of scenarios, while expanded treatment interventions are likely to be substantially less effective. Our modelled interventions in our simulated study populations are expected to have little effect on HIV, and in some scenarios lead to small increases in HIV incidence, suggesting that interventions against syphilis should be accompanied with interventions against other sexually transmitted infections to prevent the possibility that lower morbidity or lower perceived risk from syphilis could lead to increases in other sexually transmitted diseases.

  16. Attenuation studies of booster-rocket propellants and their simulants

    Energy Technology Data Exchange (ETDEWEB)

    Weirick, L.J.

    1990-08-01

    A series of impact experiments on a composite propellant, an energetic propellant, and their simulants was recently completed using a light-gas gun. Previous experiments were done to obtain Hugoniot data, to investigate the pressure threshold at which a reaction occurs, and to measure spall damage at various impact velocities. The present studies measured the attenuation of shock waves in these materials, completing the shock characterization needed for material modeling. An initial impulse of 2.0 GPa magnitude and {approximately}0.6 {mu}s duration was imposed upon samples of various thicknesses. VISAR was used to measure the free-surface velocity at the back of the samples; these data were used to generate a curve of shock-wave attenuation versus sample thickness for each material. Results showed that all four materials attenuated the shock wave very similarly. Material thicknesses of 3.0, 7.62, 12.7, and 19.0 mm attenuated the shock wave {approximately}16%, 33%, 50%, and 66% respectively. 14 refs., 12 figs., 4 tabs.

  17. The study, design and simulation of a free piston Stirling engine linear alternatorThe study, design and simulation of a free piston Stirling engine linear alternator

    Directory of Open Access Journals (Sweden)

    Teodora Susana Oros

    2014-12-01

    Full Text Available This paper presents a study, design and simulation of a Free Piston Stirling Engine Linear Alternator. There are presented the main steps of the magnetic and electric calculations for a permanent magnet linear alternator of fixed coil and moving magnets type. Finally, a detailed thermal, mechanical and electrical model for a Stirling engine linear alternator have been made in SIMULINK simulation program. The linear alternator simulation model uses a controllable DC voltage which simulates the linear alternator combined with a rectifier, a variable load and a DC-DC converter, which compensates for the variable nature of Stirling engine operation, and ensures a constant voltage output regardless of the load.

  18. IUS/payload communication system simulator configuration definition study. [payload simulator for pcm telemetry

    Science.gov (United States)

    Udalov, S.; Springett, J. C.

    1978-01-01

    The requirements and specifications for a general purpose payload communications system simulator to be used to emulate those communications system portions of NASA and DOD payloads/spacecraft that will in the future be carried into earth orbit by the shuttle are discussed. For the purpose of on-orbit checkout, the shuttle is required to communicate with the payloads while they are physically located within the shuttle bay (attached) and within a range of 20 miles from the shuttle after they have been deployed (detached). Many of the payloads are also under development (and many have yet to be defined), actual payload communication hardware will not be available within the time frame during which the avionic hardware tests will be conducted. Thus, a flexible payload communication system simulator is required.

  19. Seventeenth Workshop on Computer Simulation Studies in Condensed-Matter Physics

    CERN Document Server

    Landau, David P; Schütler, Heinz-Bernd; Computer Simulation Studies in Condensed-Matter Physics XVI

    2006-01-01

    This status report features the most recent developments in the field, spanning a wide range of topical areas in the computer simulation of condensed matter/materials physics. Both established and new topics are included, ranging from the statistical mechanics of classical magnetic spin models to electronic structure calculations, quantum simulations, and simulations of soft condensed matter. The book presents new physical results as well as novel methods of simulation and data analysis. Highlights of this volume include various aspects of non-equilibrium statistical mechanics, studies of properties of real materials using both classical model simulations and electronic structure calculations, and the use of computer simulations in teaching.

  20. A simulation study of TaMAC protocol using network simulator 2.

    Science.gov (United States)

    Ullah, Sana; Kwak, Kyung Sup

    2012-10-01

    A Wireless Body Area Network (WBAN) is expected to play a significant role in future healthcare system. It interconnects low-cost and intelligent sensor nodes in, on, or around a human body to serve a variety of medical applications. It can be used to diagnose and treat patients with chronic diseases such as hypertensions, diabetes, and cardiovascular diseases. The lightweight sensor nodes integrated in WBAN require low-power operation, which can be achieved using different optimization techniques. We introduce a Traffic-adaptive MAC protocol (TaMAC) for WBAN that supports dual wakeup mechanisms for normal, emergency, and on-demand traffic. In this letter, the TaMAC protocol is simulated using a well-known Network Simulator 2 (NS-2). The problem of multiple emergency nodes is solved using both wakeup radio and CSMA/CA protocol. The power consumption, delay, and throughput performance are closely compared with beacon-enabled IEEE 802.15.4 MAC protocol using extensive simulations.

  1. Guidance Provided by Teacher and Simulation for Inquiry-Based Learning: a Case Study

    Science.gov (United States)

    Lehtinen, Antti; Viiri, Jouni

    2017-04-01

    Current research indicates that inquiry-based learning should be guided in order to achieve optimal learning outcomes. The need for guidance is even greater when simulations are used because of their high information content and the difficulty of extracting information from them. Previous research on guidance for learning with simulations has concentrated on guidance provided by the simulation. Little research has been done on the role of the teacher in guiding learners with inquiry-based activities using simulations. This descriptive study focuses on guidance provided during small group investigations; pre-service teachers ( n = 8) guided third and fifth graders using a particular simulation. Data was collected using screen capture videos. The data was analyzed using a combination of theory- and data-driven analysis. Forms of guidance provided by the simulation and by the teachers were divided into the same categories. The distribution of the guidance between the teacher and the simulation was also analyzed. The categories for forms of guidance provided by simulations proved to be applicable to guidance provided by the teachers as well. Teachers offered more various forms of guidance than the simulation. The teachers adapted their guidance and used different patterns to complement the guidance provided by the simulation. The results of the study show that guidance provided by teachers and simulations have different affordances, and both should be present in the classroom for optimal support of learning. This has implications for both teaching with simulations and development of new simulations.

  2. Pressure swing distillation of azeotropic mixture – A simulation study

    Directory of Open Access Journals (Sweden)

    Asma Iqbal

    2016-09-01

    Full Text Available The aim of this work is to simulate a pressure-swing distillation column for the separation and purification of ethanol from the ethanol–water binary system. The choice for this system is due to the importance of the ethanol–water separation. A steady-state equilibrium-stage model based on normalised MESH equations is used to simulate pressure-swing distillation column applied for the production of ethanol. All the work has been carried out using Aspen Plus simulator, version 13.2. Among the activity coefficient models available, the WILSON-RK model with binary parameters predicted by the Aspen Plus simulator is shown to be the most accurate to correlate the experimental vapor-/liquid equilibrium (VLE data available for the ethanol–water system. The simulation has been satisfactorily carried out for a mixture of 20 mol% ethanol in water at 1 atm pressure and 90 °C with a molar flow rate of 100 kmol/h. The adjusting parameters include D/F ratio and reflux ratio of the two columns to get water purity of 99.5 mol% from the bottom of the Low Pressure Column (LPC and the ethanol purity of 99.7 mol% from the bottom of High Pressure Column (HPC.

  3. A Study on the LEED Energy Simulation Process Using BIM

    Directory of Open Access Journals (Sweden)

    Han-Soo Ryu

    2016-02-01

    Full Text Available In the domestic and international environmentally friendly certification system, energy-related credit occupies a high ratio in the total distribution of certification score Leadership in the Energy and Environmental Design (LEED system is a certification system developed by the US Green Building Council (USGBC in order to assess the environmental friendliness of buildings. The energy-related credit is approximately 30% of the total and also the energy simulation ratio specifically is the highest among the single credits as it is 20%. In this research, the energy simulation process using Building Information Modeling (BIM based on the energy simulation case performed at the A-Tower, LEED certification was proposed. It places an emphasis on the verification process which was short in the previous research. The architectural geometry modeled through the BIM tool is converted to the gbXML, and in this process the geometry is verified through the interference check functions, the gbXML Viewer and the FZKViewer. The energy simulation is performed after the verification procedure. The geometry verification process in the A-Tower project is presented throughout this paper. In conclusion, an improved process is proposed for the productivity and reliability of energy simulation.

  4. Preliminary Modeling and Simulation Study on Olfactory Cell Sensation

    Science.gov (United States)

    Zhou, Jun; Yang, Wei; Chen, Peihua; Liu, Qingjun; Wang, Ping

    2009-05-01

    This paper introduced olfactory sensory neuron's whole-cell model with a concrete voltage-gated ionic channels and simulation. Though there are many models in olfactory sensory neuron and olfactory bulb, it remains uncertain how they express the logic of olfactory information processing. In this article, the olfactory neural network model is also introduced. This model specifies the connections among neural ensembles of the olfactory system. The simulation results of the neural network model are consistent with the observed olfactory biological characteristics such as 1/f-type power spectrum and oscillations.

  5. Development of a simulation environment to study emergency department information technology.

    Science.gov (United States)

    Pennathur, Priyadarshini R; Cao, Dapeng; Sui, Zheng; Lin, Li; Bisantz, Ann M; Fairbanks, Rollin J; Guarrera, Theresa K; Brown, Jennifer L; Perry, Shawna J; Wears, Robert L

    2010-04-01

    This article presents a simulation architecture for a patient tracking system simulator to study caregiver performance in emergency departments (EDs). The architecture integrates discrete event simulation modeling with clinical patient information. Evaluation components for electronic patient tracking system displays are also described. A simulation of an ED electronic whiteboard was developed to study situation awareness metrics. Dynamic process data from an actual ED was used to generate simulation parameters including patient arrivals at various hours, distribution of severities, times required to treat the ED patients, and ancillary turnaround times (laboratory and radiology). A team of industrial engineers and ED physicians contributed demographic and clinical information for simulator patients. ED simulation parameters were combined with clinical information resulting in an event timeline database. Event timelines were used to populate a front-end patient-tracking system display simulation. The resulting patient-tracking system display simulation consists of underlying software, desktop and large-screen displays, a phone call/pager system, and typical tasks that enhance the realism of the simulation experience. The system can evaluate the impact of display parameters and ED operations on user performance. Modular design of the patient-tracking system display simulation helps adaptation for different studies to support various interface features and interaction types. The methodology described in this work exploits the benefits of discrete event simulation to iteratively design and test technologies such as electronic patient tracking systems and allows assessment of human performance measures.

  6. Decoding the Dopamine Signal in Macaque Prefrontal Cortex: A Simulation Study Using the Cx3Dp Simulator

    Science.gov (United States)

    Spühler, Isabelle Ayumi; Hauri, Andreas

    2013-01-01

    Dopamine transmission in the prefrontal cortex plays an important role in reward based learning, working memory and attention. Dopamine is thought to be released non-synaptically into the extracellular space and to reach distant receptors through diffusion. This simulation study examines how the dopamine signal might be decoded by the recipient neuron. The simulation was based on parameters from the literature and on our own quantified, structural data from macaque prefrontal area 10. The change in extracellular dopamine concentration was estimated at different distances from release sites and related to the affinity of the dopamine receptors. Due to the sparse and random distribution of release sites, a transient heterogeneous pattern of dopamine concentration emerges. Our simulation predicts, however, that at any point in the simulation volume there is sufficient dopamine to bind and activate high-affinity dopamine receptors. We propose that dopamine is broadcast to its distant receptors and any change from the local baseline concentration might be decoded by a transient change in the binding probability of dopamine receptors. Dopamine could thus provide a graduated ‘teaching’ signal to reinforce concurrently active synapses and cell assemblies. In conditions of highly reduced or highly elevated dopamine levels the simulations predict that relative changes in the dopamine signal can no longer be decoded, which might explain why cognitive deficits are observed in patients with Parkinson’s disease, or induced through drugs blocking dopamine reuptake. PMID:23951205

  7. Decoding the dopamine signal in macaque prefrontal cortex: a simulation study using the Cx3Dp simulator.

    Directory of Open Access Journals (Sweden)

    Isabelle Ayumi Spühler

    Full Text Available Dopamine transmission in the prefrontal cortex plays an important role in reward based learning, working memory and attention. Dopamine is thought to be released non-synaptically into the extracellular space and to reach distant receptors through diffusion. This simulation study examines how the dopamine signal might be decoded by the recipient neuron. The simulation was based on parameters from the literature and on our own quantified, structural data from macaque prefrontal area 10. The change in extracellular dopamine concentration was estimated at different distances from release sites and related to the affinity of the dopamine receptors. Due to the sparse and random distribution of release sites, a transient heterogeneous pattern of dopamine concentration emerges. Our simulation predicts, however, that at any point in the simulation volume there is sufficient dopamine to bind and activate high-affinity dopamine receptors. We propose that dopamine is broadcast to its distant receptors and any change from the local baseline concentration might be decoded by a transient change in the binding probability of dopamine receptors. Dopamine could thus provide a graduated 'teaching' signal to reinforce concurrently active synapses and cell assemblies. In conditions of highly reduced or highly elevated dopamine levels the simulations predict that relative changes in the dopamine signal can no longer be decoded, which might explain why cognitive deficits are observed in patients with Parkinson's disease, or induced through drugs blocking dopamine reuptake.

  8. Focus on Games & Simulations: Trends+Technologies+Case Studies

    Science.gov (United States)

    Weinstein, Margery

    2010-01-01

    The youngest workforce generation seems to crave games and simulations, and even older workers are coming to enjoy them. But what do new trends in these areas mean for the company, the learners, and the organization's strategic goals? In this article, two experts in the field, Clarissa Graffeo and David Metcalf of the Mixed Emerging Technology…

  9. Soil Erosion Study through Simulation: An Educational Tool.

    Science.gov (United States)

    Huber, Thomas P.; Falkenmayer, Karen

    1987-01-01

    Discusses the need for education about soil erosion and advocates the use of the Universal Soil Loss Equation (USLE) to show the impacts of human and natural action on the land. Describes the use of a computer simulated version of the USLE in several environmental and farming situations. (TW)

  10. Credible Mobile and Ad Hoc Network Simulation-Based Studies

    Science.gov (United States)

    2006-10-26

    once duplicate (orange) Received the same packet twice 2-duplicates ( pink ) Received the same packet at least three times 4-duplicates (red) Received...mobility tool generators in NS-2 simulator. Version 1.0, beta, 2004. [6] S. Bajaj, L. Breslau, D. Estrin, K. Fall, S. Floyd , P. Haldar, M. Hand- ley, A

  11. Implementing a Simulation Study Using Multiple Software Packages for Structural Equation Modeling

    Directory of Open Access Journals (Sweden)

    Sunbok Lee

    2015-07-01

    Full Text Available A Monte Carlo simulation study is an essential tool for evaluating the behavior of various quantitative methods including structural equation modeling (SEM under various conditions. Typically, a large number of replications are recommended for a Monte Carlo simulation study, and therefore automating a Monte Carlo simulation study is important to get the desired number of replications for a simulation study. This article is intended to provide concrete examples for automating a Monte Carlo simulation study using some standard software packages for SEM: Mplus, LISREL, SAS PROC CALIS, and R package lavaan. Also, the equivalence between the multilevel SEM and hierarchical linear modeling (HLM is discussed, and relevant examples are provided. It is hoped that the codes in this article can provide some building blocks for researchers to write their own code to automate simulation procedures.

  12. When to conduct probabilistic linkage vs. deterministic linkage? A simulation study

    National Research Council Canada - National Science Library

    Zhu, Ying; Matsuyama, Yutaka; Ohashi, Yasuo; Setoguchi, Soko

    2015-01-01

    ... to variations in data quality, implementation of linkage methodology and validation method. The simulation study aimed to understand data characteristics that affect the performance of probabilistic vs...

  13. SED-ML web tools: generate, modify and export standard-compliant simulation studies.

    Science.gov (United States)

    Bergmann, Frank T; Nickerson, David; Waltemath, Dagmar; Scharm, Martin

    2017-04-15

    The Simulation Experiment Description Markup Language (SED-ML) is a standardized format for exchanging simulation studies independently of software tools. We present the SED-ML Web Tools, an online application for creating, editing, simulating and validating SED-ML documents. The Web Tools implement all current SED-ML specifications and, thus, support complex modifications and co-simulation of models in SBML and CellML formats. Ultimately, the Web Tools lower the bar on working with SED-ML documents and help users create valid simulation descriptions. http://sysbioapps.dyndns.org/SED-ML_Web_Tools/ . fbergman@caltech.edu .

  14. Stochastic exposure kinetics of EUV photoresists: a simulation study

    Science.gov (United States)

    Mack, Chris A.; Thackeray, James W.; Biafore, John J.; Smith, Mark D.

    2011-04-01

    BACKGROUND: The stochastic nature of extreme ultraviolet (EUV) resist exposure leads to variations in the resulting acid concentration, which leads to line-edge roughness (LER) of the resulting features. METHODS: Using a stochastic resist simulator, we predicted the mean and standard deviation of the acid concentration for an open-frame exposure and fit the results to analytical expressions. RESULTS: The EUV resist exposure mechanism of the PROLTIH Stochastic Resist Simulator is first order, and an analytical expression for the exposure rate constant C allows prediction of the mean acid concentration of an open-frame exposure to about 1% accuracy over a wide range of parameter values. A second analytical expression for the standard deviation of the acid concentration also matched the output of PROLITH to within about 1%. CONCLUSIONS: Predicting the stochastic uncertainty in acid concentration for EUV resists allows optimization of resist processing and formulations, and may form the basis of a comprehensive LER model.

  15. 3D Simulation Studies of SNS Ring Doublet Magnets

    CERN Document Server

    Wang, Jian-Guang; Venturini, Marco

    2005-01-01

    The accumulator ring of the Spallation Neutron Source (SNS) at ORNL employs in its straight sections closely packed quadrupole doublet magnets with large aperture of R=15.1 cm and relatively short iron-to-iron distance of 51.4 cm.* The magnetic interference among the magnets in the doublet assemblies is not avoidable due to the fringe fields. Though each magnet in the assemblies has been individually mapped to high accuracy of delta(B)/B~1x10-4, the experimental data including the magnet interference effect in the assemblies will not be available. We have performed 3D computer simulations on a quadrupole doublet model in order to assess the degree of the interference and to obtain relevant data which should be very useful for the SNS commissioning and operation. This paper reports our simulation results.

  16. Numerical simulation of study and unsteady sheet cavitation

    Energy Technology Data Exchange (ETDEWEB)

    Schnerr, G.H.; Spengler, C. (Karlsruhe Univ. (T.H.) (Germany). Abt. Stroemungsmaschinen)

    1998-01-01

    The aim of the work is to provide an efficient code to simulate developed sheet cavitation including the unsteady behavior at the end of the sheet. The vapor region is calculated directly by using a 'compressible system' of equations. To simulate the liquid phase an 'incompressible system' of equations is used. The numerical method is based on an extended method of artificial compressibility which allows the simultaneous calculation of compressible and incompressible flows. To verify the code a first cavitating result of the inviscid flow around a NACA0012 hydrofoil at a Mach number M=0.1, an angle of attack [alpha]=4 , and a cavitation number [sigma]=1.0 is presented. (orig.)

  17. Numerical simulation of study and unsteady sheet cavitation

    Energy Technology Data Exchange (ETDEWEB)

    Schnerr, G.H.; Spengler, C. [Karlsruhe Univ. (T.H.) (Germany). Abt. Stroemungsmaschinen

    1998-12-31

    The aim of the work is to provide an efficient code to simulate developed sheet cavitation including the unsteady behavior at the end of the sheet. The vapor region is calculated directly by using a `compressible system` of equations. To simulate the liquid phase an `incompressible system` of equations is used. The numerical method is based on an extended method of artificial compressibility which allows the simultaneous calculation of compressible and incompressible flows. To verify the code a first cavitating result of the inviscid flow around a NACA0012 hydrofoil at a Mach number M=0.1, an angle of attack {alpha}=4 , and a cavitation number {sigma}=1.0 is presented. (orig.)

  18. A study for production simulation model generation system based on data model at a shipyard

    Directory of Open Access Journals (Sweden)

    Myung-Gi Back

    2016-09-01

    Full Text Available Simulation technology is a type of shipbuilding product lifecycle management solution used to support production planning or decision-making. Normally, most shipbuilding processes are consisted of job shop production, and the modeling and simulation require professional skills and experience on shipbuilding. For these reasons, many shipbuilding companies have difficulties adapting simulation systems, regardless of the necessity for the technology. In this paper, the data model for shipyard production simulation model generation was defined by analyzing the iterative simulation modeling procedure. The shipyard production simulation data model defined in this study contains the information necessary for the conventional simulation modeling procedure and can serve as a basis for simulation model generation. The efficacy of the developed system was validated by applying it to the simulation model generation of the panel block production line. By implementing the initial simulation model generation process, which was performed in the past with a simulation modeler, the proposed system substantially reduced the modeling time. In addition, by reducing the difficulties posed by different modeler-dependent generation methods, the proposed system makes the standardization of the simulation model quality possible.

  19. Control of a wrist joint motion simulator: A phantom study.

    Science.gov (United States)

    Shah, Darshan S; Kedgley, Angela E

    2016-09-06

    The presence of muscle redundancy and co-activation of agonist-antagonist pairs in vivo makes the optimization of the load distribution between muscles in physiologic joint simulators vital. This optimization is usually achieved by employing different control strategies based on position and/or force feedback. A muscle activated physiologic wrist simulator was developed to test and iteratively refine such control strategies on a functional replica of a human arm. Motions of the wrist were recreated by applying tensile loads using electromechanical actuators. Load cells were used to monitor the force applied by each muscle and an optical motion capture system was used to track joint angles of the wrist in real-time. Four control strategies were evaluated based on their kinematic error, repeatability and ability to vary co-contraction. With kinematic errors of less than 1.5°, the ability to vary co-contraction, and without the need for predefined antagonistic forces or muscle force ratios, novel control strategies - hybrid control and cascade control - were preferred over standard control strategies - position control and force control. Muscle forces obtained from hybrid and cascade control corresponded well with in vivo EMG data and muscle force data from other wrist simulators in the literature. The decoupling of the wrist axes combined with the robustness of the control strategies resulted in complex motions, like dart thrower׳s motion and circumduction, being accurate and repeatable. Thus, two novel strategies with repeatable kinematics and physiologically relevant muscle forces are introduced for the control of joint simulators. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  20. The Human Operator Simulator. Volume IX. HOS Study Guide.

    Science.gov (United States)

    1978-09-01

    TqACK-BALL-POSITION. MOVE THE TPACK -RALL TO THE RESULT. IF THE RATE OF THE TRACK-BALL IS NOT 0,0 INCHES THEN WAIT. GO TO CHFCK NOW. DEFINE THE...MIDFNO: CHANGE THE TOACK-BALL TO THE NEw-BALL-POSITION. END: CHANGE THE PATE OF THE TPACK -ALL TO 0.0 INCHES. EN0. Figure 39. Procedure to simulate the

  1. A study on naphtha catalytic reforming reactor simulation and analysis

    OpenAIRE

    Liang, Ke-min; Guo, Hai-Yan; Pan, Shi-Wei

    2005-01-01

    A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation uni...

  2. A study on naphtha catalytic reforming reactor simulation and analysis.

    Science.gov (United States)

    Liang, Ke-min; Guo, Hai-yan; Pan, Shi-wei

    2005-06-01

    A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by single compounds. The simulation results based above models agree very well with actual operation unit data.

  3. Adapting a Driving Simulator to Study Pedestrians' Street-Crossing Decisions: A Feasibility Study.

    Science.gov (United States)

    Jäger, M; Nyffeler, T; Müri, R; Mosimann, U P; Nef, T

    2015-01-01

    The decision when to cross a street safely is a challenging task that poses high demands on perception and cognition. Both can be affected by normal aging, neurodegenerative disorder, and brain injury, and there is an increasing interest in studying street-crossing decisions. In this article, we describe how driving simulators can be modified to study pedestrians' street-crossing decisions. The driving simulator's projection system and the virtual driving environment were used to present street-crossing scenarios to the participants. New sensors were added to measure when the test person starts to cross the street. Outcome measures were feasibility, usability, task performance, and visual exploration behavior, and were measured in 15 younger persons, 15 older persons, and 5 post-stroke patients. The experiments showed that the test is feasible and usable, and the selected difficulty level was appropriate. Significant differences in the number of crashes between young participants and patients (p = .001) as well as between healthy older participants and patients (p = .003) were found. When the approaching vehicle's speed is high, significant differences between younger and older participants were found as well (p = .038). Overall, the new test setup was well accepted, and we demonstrated that driving simulators can be used to study pedestrians' street-crossing decisions.

  4. Community Heterogeneity : A Burden for the Creation of Social Capital?

    NARCIS (Netherlands)

    Coffé, Hilde; Geys, Benny

    2006-01-01

    Objective. This study examines the relationship between community heterogeneity and social capital on the local government level. Method. We apply both OLS and interval regression techniques to objective macro data of 307 Flemish municipalities for the year 2000. Results. Our results show that,

  5. Molecular simulation studies on thermophysical properties with application to working fluids

    CERN Document Server

    Raabe, Gabriele

    2017-01-01

    This book discusses the fundamentals of molecular simulation, starting with the basics of statistical mechanics and providing introductions to Monte Carlo and molecular dynamics simulation techniques. It also offers an overview of force-field models for molecular simulations and their parameterization, with a discussion of specific aspects. The book then summarizes the available know-how for analyzing molecular simulation outputs to derive information on thermophysical and structural properties. Both the force-field modeling and the analysis of simulation outputs are illustrated by various examples. Simulation studies on recently introduced HFO compounds as working fluids for different technical applications demonstrate the value of molecular simulations in providing predictions for poorly understood compounds and gaining a molecular-level understanding of their properties. This book will prove a valuable resource to researchers and students alike.

  6. Molecular dynamics simulation studies of tailored nanostructured polymers

    Science.gov (United States)

    Liu, Lixin

    With recent advancements in the synthesis and characterization of polymeric materials, scientists are able to create multi-scale novel polymers with various cases of chemical functionalities, diversified topologies, as well as cross-linking networks. Due to those remarkable achievements, there are a broad range of possible applications of smart polymers in catalysis, in environmental remediation, and especially in drug-delivery. Because of rising interest in developing therapeutic drug binding to specific treating target, polymer chemists are in particular interests in design and engineering the drug delivery materials to be not only bio-compatible, but also to be capable of self-assembly at various in-vivo physiological stimulus. Both experimental and theoretical work indicate that the thermodynamic properties relating to the hydrophobic effect play an important role in determining self-assembly process. At the same time, computational simulation and modeling are powerful instruments to contribute to microscopic thermodynamics' understanding toward self-assembly phenomenon. Along with statistical approaches, constructing empirical model based on simulation results would also help predict for further development of tailored nano-structured materials. My Research mainly focused on investigating physical and chemical characteristics of polymer materials through molecular dynamics simulation and probing the fundamental thermodynamic driving force of self-assembly behavior. We tried to surmount technological obstacles in computational chemistry and build an efficient scheme to identify the physical and chemical Feature of molecules, to reproduce underlying properties, to understand the origin of thermodynamic signatures, and to speed up current trial and error process in screening new materials.

  7. Simulation study of the plasma-brake effect

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2014-10-01

    Full Text Available Plasma brake is a thin, negatively biased tether that has been proposed as an efficient concept for deorbiting satellites and debris objects from low Earth orbit. We simulate the interaction with the ionospheric plasma ram flow with the plasma-brake tether by a high-performance electrostatic particle in cell code to evaluate the thrust. The tether is assumed to be perpendicular to the flow. We perform runs for different tether voltage, magnetic-field orientation and plasma-ion mass. We show that a simple analytical thrust formula reproduces most of the simulation results well. The interaction with the tether and the plasma flow is laminar (i.e. smooth and not turbulent when the magnetic field is perpendicular to the tether and the flow. If the magnetic field is parallel to the tether, the behaviour is unstable and thrust is reduced by a modest factor. The case in which the magnetic field is aligned with the flow can also be unstable, but does not result in notable thrust reduction. We also correct an error in an earlier reference. According to the simulations, the predicted thrust of the plasma brake is large enough to make the method promising for low-Earth-orbit (LEO satellite deorbiting. As a numerical example, we estimate that a 5 km long plasma-brake tether weighing 0.055 kg could produce 0.43 mN breaking force, which is enough to reduce the orbital altitude of a 260 kg object mass by 100 km over 1 year.

  8. Simulation study of the elastic mechanical properties of HMX

    Energy Technology Data Exchange (ETDEWEB)

    Sewell, T. D. (Thomas D.)

    2002-01-01

    Results of calculations of the elastic mechanical response of crystalline HMX polymorphs are summarized. The work is based on atomistic molecular dynamics and Monte Carlo simulations. Principal achievements are: (1) prediction of room temperature and pressure elastic tensors for {beta}-, {alpha}- and {delta}-HMX; (2) calculation of room temperature isotherms for each polymorph; (3) extraction of initial bulk modulus and pressure derivative from the isotherm; and (4) 'discovery' of a pressure induced phase transition in {alpha}-HMX (preliminary result). Details of the work, and implications, will be discussed.

  9. HCIT Contrast Performance Sensitivity Studies: Simulation Versus Experiment

    Science.gov (United States)

    Sidick, Erkin; Shaklan, Stuart; Krist, John; Cady, Eric J.; Kern, Brian; Balasubramanian, Kunjithapatham

    2013-01-01

    Using NASA's High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Laboratory, we have experimentally investigated the sensitivity of dark hole contrast in a Lyot coronagraph for the following factors: 1) Lateral and longitudinal translation of an occulting mask; 2) An opaque spot on the occulting mask; 3) Sizes of the controlled dark hole area. Also, we compared the measured results with simulations obtained using both MACOS (Modeling and Analysis for Controlled Optical Systems) and PROPER optical analysis programs with full three-dimensional near-field diffraction analysis to model HCIT's optical train and coronagraph.

  10. A simulation study in dynamic 'Utah'-models

    DEFF Research Database (Denmark)

    Toldam-Andersen, Torben Bo

    1992-01-01

    major variants: I) Models involving a procedure which makes it possible to include the dynamic relationship between chilling and heat requirement. II) Models involving a chain structure with each "link" representing a develop­mental phase through the dormancy period. Based on the teories proposed...... by Saure (1985), the temperature response of the system was adjusted in each phase in arder to simulate the change in the temperature response of the dormant tree. Tue proposed models were used to predict the beginning of flowering inAlnus and Betula, which are closely related species, but shows great...

  11. Simulation Environment for Orion Launch Abort System Control Design Studies

    Science.gov (United States)

    McMinn, J. Dana; Jackson, E. Bruce; Christhilf, David M.

    2007-01-01

    The development and use of an interactive environment to perform control system design and analysis of the proposed Crew Exploration Vehicle Launch Abort System is described. The environment, built using a commercial dynamic systems design package, includes use of an open-source configuration control software tool and a collaborative wiki to coordinate between the simulation developers, control law developers and users. A method for switching between multiple candidate control laws and vehicle configurations is described. Aerodynamic models, especially in a development program, change rapidly, so a means for automating the implementation of new aerodynamic models is described.

  12. A Proxy Outcome Approach for Causal Effect in Observational Studies: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Wenbin Liang

    2014-01-01

    Full Text Available Background. Known and unknown/unmeasured risk factors are the main sources of confounding effects in observational studies and can lead to false observations of elevated protective or hazardous effects. In this study, we investigate an alternative approach of analysis that is operated on field-specific knowledge rather than pure statistical assumptions. Method. The proposed approach introduces a proxy outcome into the estimation system. A proxy outcome possesses the following characteristics: (i the exposure of interest is not a cause for the proxy outcome; (ii causes of the proxy outcome and the study outcome are subsets of a collection of correlated variables. Based on these two conditions, the confounding-effect-driven association between the exposure and proxy outcome can then be measured and used as a proxy estimate for the effects of unknown/unmeasured confounders on the outcome of interest. Performance of this approach is tested by a simulation study, whereby 500 different scenarios are generated, with the causal factors of a proxy outcome and a study outcome being partly overlapped under low-to-moderate correlations. Results. The simulation results demonstrate that the conventional approach only led to a correct conclusion in 21% of the 500 scenarios, as compared to 72.2% for the alternative approach. Conclusion. The proposed method can be applied in observational studies in social science and health research that evaluates the health impact of behaviour and mental health problems.

  13. Membrane Permeability of Fatty Acyl Compounds Studied via Molecular Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Vermaas, Josh V. [Biosciences; Beckham, Gregg T. [National; Crowley, Michael F. [Biosciences

    2017-11-01

    Interest in fatty acid-derived products as fuel and chemical precursors has grown substantially. Microbes can be genetically engineered to produce fatty acid-derived products that are able to cross host membranes and can be extracted into an applied organic overlay. This process is thought to be passive, with a rate dependent on the chemistry of the crossing compound. The relationship between the chemical composition and the energetics and kinetics of product accumulation within the overlay is not well understood. Through biased and unbiased molecular simulation, we compute the membrane permeability coefficients from production to extraction for different fatty acyl products, including fatty acids, fatty alcohols, fatty aldehydes, alkanes, and alkenes. These simulations identify specific interactions that accelerate the transit of aldehydes across the membrane bilayer relative to other oxidized products, specifically the lack of hydrogen bonds to the surrounding membrane environment. However, since extraction from the outer membrane leaflet into the organic phase is found to be rate limiting for the entire process, we find that fatty alcohols and fatty aldehydes would both manifest similar fluxes into a dodecane overlay under equivalent conditions, outpacing the accumulation of acids or alkanes into the organic phase. Since aldehydes are known to be highly reactive as well as toxic in high quantities, the findings suggest that indeed fatty alcohols are the optimal long-tail fatty acyl product for extraction.

  14. Short-duration Electron Precipitation Studied by Test Particle Simulation

    Directory of Open Access Journals (Sweden)

    Jaejin Lee

    2015-12-01

    Full Text Available Energy spectra of electron microbursts from 170 keV to 340 keV have been measured by the solid-state detectors aboard the low-altitude (680 km polar-orbiting Korean STSAT-1 (Science and Technology SATellite. These measurements have revealed two important characteristics unique to the microbursts: (1 They are produced by a fast-loss cone-filling process in which the interaction time for pitch-angle scattering is less than 50 ms and (2 The e-folding energy of the perpendicular component is larger than that of the parallel component, and the loss cone is not completely filled by electrons. To understand how wave-particle interactions could generate microbursts, we performed a test particle simulation and investigated how the waves scattered electron pitch angles within the timescale required for microburst precipitation. The application of rising-frequency whistler-mode waves to electrons of different energies moving in a dipole magnetic field showed that chorus magnetic wave fields, rather than electric fields, were the main cause of microburst events, which implied that microbursts could be produced by a quasi-adiabatic process. In addition, the simulation results showed that high-energy electrons could resonate with chorus waves at high magnetic latitudes where the loss cone was larger, which might explain the decreased e-folding energy of precipitated microbursts compared to that of trapped electrons.

  15. Pilot In-Trail Procedure Validation Simulation Study

    Science.gov (United States)

    Bussink, Frank J. L.; Murdoch, Jennifer L.; Chamberlain, James P.; Chartrand, Ryan; Jones, Kenneth M.

    2008-01-01

    A Human-In-The-Loop experiment was conducted at the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) to investigate the viability of the In-Trail Procedure (ITP) concept from a flight crew perspective, by placing participating airline pilots in a simulated oceanic flight environment. The test subject pilots used new onboard avionics equipment that provided improved information about nearby traffic and enabled them, when specific criteria were met, to request an ITP flight level change referencing one or two nearby aircraft that might otherwise block the flight level change. The subject pilots subjective assessments of ITP validity and acceptability were measured via questionnaires and discussions, and their objective performance in appropriately selecting, requesting, and performing ITP flight level changes was evaluated for each simulated flight scenario. Objective performance and subjective workload assessment data from the experiment s test conditions were analyzed for statistical and operational significance and are reported in the paper. Based on these results, suggestions are made to further improve the ITP.

  16. Study of Hydrokinetic Turbine Arrays with Large Eddy Simulation

    Science.gov (United States)

    Sale, Danny; Aliseda, Alberto

    2014-11-01

    Marine renewable energy is advancing towards commercialization, including electrical power generation from ocean, river, and tidal currents. The focus of this work is to develop numerical simulations capable of predicting the power generation potential of hydrokinetic turbine arrays-this includes analysis of unsteady and averaged flow fields, turbulence statistics, and unsteady loadings on turbine rotors and support structures due to interaction with rotor wakes and ambient turbulence. The governing equations of large-eddy-simulation (LES) are solved using a finite-volume method, and the presence of turbine blades are approximated by the actuator-line method in which hydrodynamic forces are projected to the flow field as a body force. The actuator-line approach captures helical wake formation including vortex shedding from individual blades, and the effects of drag and vorticity generation from the rough seabed surface are accounted for by wall-models. This LES framework was used to replicate a previous flume experiment consisting of three hydrokinetic turbines tested under various operating conditions and array layouts. Predictions of the power generation, velocity deficit and turbulence statistics in the wakes are compared between the LES and experimental datasets.

  17. Low Energy Defibrillation in Human Cardiac Tissue: A Simulation Study

    Science.gov (United States)

    Morgan, Stuart W.; Plank, Gernot; Biktasheva, Irina V.; Biktashev, Vadim N.

    2009-02-01

    We aim to assess the effectiveness of feedback controlled resonant drift pacing as a method for low energy defibrillation. Antitachycardia pacing is the only low energy defibrillation approach to have gained clinical significance, but it is still suboptimal. Low energy defibrillation would avoid adverse side effects associated with high voltage shocks and allow the application of ICD therapy where it is not tolerated today. We present results of computer simulations of a bidomain model of cardiac tissue with human atrial ionic kinetics. Re-entry was initiated and low energy shocks were applied with the same period as the re-entry, using feedback to maintain resonance. We demonstrate that such stimulation can move the core of re-entrant patterns, in the direction depending on location of electrodes and a time delay in the feedback. Termination of re-entry is achieved with shock strength one order of magnitude weaker than in conventional single-shock defibrillation. We conclude that resonant drift pacing can terminate re-entry at a fraction of the shock strength currently used for defibrillation and can potentially work where antitachycardia pacing fails, due to the feedback mechanisms. Success depends on a number of details which these numerical simulations have uncovered. \\emph{Keywords} Re-entry; Bidomain model; Resonant drift; ICD; Defibrillation; Antitachycardia pacing; Feedback.

  18. Statistical Analysis of Large Simulated Yield Datasets for Studying Climate Effects

    NARCIS (Netherlands)

    Makowski, D.; Asseng, S.; Ewert, F.; Bassu, S.; Durand, J.L.; Martre, P.; Adam, M.; Aggarwal, P.K.; Angulo, C.; Baron, C.; Basso, B.; Bertuzzi, P.; Biernath, C.; Boogaard, H.; Boote, K.J.; Brisson, N.; Cammarano, D.; Challinor, A.J.; Conijn, J.G.; Corbeels, M.; Deryng, D.; Sanctis, De G.; Doltra, J.; Gayler, S.; Goldberg, R.; Grassini, P.; Hatfield, J.L.; Heng, L.; Hoek, S.B.; Hooker, J.; Hunt, L.A.; Ingwersen, J.; Izaurralde, C.; Jongschaap, R.E.E.; Jones, J.W.; Kemanian, R.A.; Kersebaum, K.C.; Kim, S.H.; Lizaso, J.; Müller, C.; Naresh Kumar, S.; Nendel, C.; O'Leary, G.J.; Olesen, J.E.; Osborne, T.M.; Palosuo, T.; Pravia, M.V.; Priesack, E.; Ripoche, D.; Rosenzweig, C.; Ruane, A.C.; Sau, F.; Semenov, M.A.; Shcherbak, I.; Steduto, P.; Stöckle, C.O.; Stratonovitch, P.; Streck, T.; Supit, I.; Tao, F.; Teixeira, E.; Thorburn, P.; Timlin, D.; Travasso, M.; Roetter, R.P.; Waha, K.; Wallach, D.; White, J.W.; Williams, J.R.; Wolf, J.

    2015-01-01

    Many simulation studies have been carried out to predict the effect of climate change on crop yield. Typically, in such study, one or several crop models are used to simulate series of crop yield values for different climate scenarios corresponding to different hypotheses of temperature, CO2

  19. Three-dimensional simulation studies of 10 MeV, 352.2 MHz drift ...

    Indian Academy of Sciences (India)

    Three-dimensional simulation studies of 10 MeV,. 352.2 MHz drift tube Linac. NITA S KULKARNI ... This paper presents the details of the studies and analysis of 3D simulations of post-couplers, .... stabilize the accelerating field in case of local field errors by creating a secondary coupled resonator system which is coupled to ...

  20. Geant4 fast and full simulation for Future Circular Collider studies

    Science.gov (United States)

    Zaborowska, A.

    2017-10-01

    Software for the next generation of experiments at the Future Circular Collider (FCC), should by design efficiently exploit the available computing resources and therefore support of parallel execution is a particular requirement. The simulation package of the FCC Common Software Framework (FCCSW) makes use of the Gaudi parallel data processing framework and external packages commonly used in HEP simulation, including the Geant4 simulation toolkit and the DD4HEP geometry toolkit. Using Geant4 for full simulation implies taking into account all physics processes for transporting the particles through detector material and this is highly CPU-intensive. At the early stage of detector design and for some physics studies such accuracy is not needed, making a fast parametrised simulation better suited. Geant4 provides the tools to define a parametrisation, where the overall response of the detector is simulated in a parametric way. Many experiments create their own frameworks for these fast simulation studies. The implementation for the FCC allows an interplay between the two types of simulation within Geant4. Based on the type of the particle or a region within the detector, either full or fast simulation may be performed, running the time-consuming detailed simulation only for the regions and particles of interest.

  1. Multi-Bunch Simulations of the ILC for Luminosity Performance Studies

    CERN Document Server

    White, Glen; Walker, Nicholas J

    2005-01-01

    To study the luminosity performance of the International Linear Collider (ILC) with different design parameters, a simulation was constructed that tracks a multi-bunch representation of the beam from the Damping Ring extraction through to the Interaction Point. The simulation code PLACET is used to simulate the LINAC, MatMerlin is used to track through the Beam Delivery System and GUINEA-PIG for the beam-beam interaction. Included in the simulation are ground motion and wakefield effects, intra-train fast feedback and luminosity-based feedback systems. To efficiently study multiple parameters/multiple seeds, the simulation is deployed on the Queen Mary High-Throughput computing cluster at Queen Mary, University of London, where 100 simultaneous simulation seeds can be run.

  2. Molecular Simulation Studies of Covalently and Ionically Grafted Nanoparticles

    Science.gov (United States)

    Hong, Bingbing

    Solvent-free covalently- or ionically-grafted nanoparticles (CGNs and IGNs) are a new class of organic-inorganic hybrid composite materials exhibiting fluid-like behaviors around room temperature. With similar structures to prior systems, e.g. nanocomposites, neutral or charged colloids, ionic liquids, etc, CGNs and IGNs inherit the functionality of inorganic nanopariticles, the facile processibility of polymers, as well as conductivity and nonvolatility from their constituent materials. In spite of the extensive prior experimental research having covered synthesis and measurements of thermal and dynamic properties, little progress in understanding of these new materials at the molecular level has been achieved, because of the lack of simulation work in this new area. Atomistic and coarse-grained molecular dynamics simulations have been performed in this thesis to investigate the thermodynamics, structure, and dynamics of these systems and to seek predictive methods predictable for their properties. Starting from poly(ethylene oxide) oligomers (PEO) melts, we established atomistic models based on united-atom representations of methylene. The Green-Kubo and Einstein-Helfand formulas were used to calculate the transport properties. The simulations generate densities, viscosities, diffusivities, in good agreement with experimental data. The chain-length dependence of the transport properties suggests that neither Rouse nor reptation models are applicable in the short-chain regime investigated. Coupled with thermodynamic integration methods, the models give good predictions of pressure-composition-density relations for CO 2 + PEO oligomers. Water effects on the Henry's constant of CO 2 in PEO have also been investigated. The dependence of the calculated Henry's constants on the weight percentage of water falls on a temperature-dependent master curve, irrespective of PEO chain length. CGNs are modeled by the inclusion of solid-sphere nanoparticles into the atomistic

  3. Multivariate Meta-Analysis of Genetic Association Studies: A Simulation Study.

    Directory of Open Access Journals (Sweden)

    Binod Neupane

    Full Text Available In a meta-analysis with multiple end points of interests that are correlated between or within studies, multivariate approach to meta-analysis has a potential to produce more precise estimates of effects by exploiting the correlation structure between end points. However, under random-effects assumption the multivariate estimation is more complex (as it involves estimation of more parameters simultaneously than univariate estimation, and sometimes can produce unrealistic parameter estimates. Usefulness of multivariate approach to meta-analysis of the effects of a genetic variant on two or more correlated traits is not well understood in the area of genetic association studies. In such studies, genetic variants are expected to roughly maintain Hardy-Weinberg equilibrium within studies, and also their effects on complex traits are generally very small to modest and could be heterogeneous across studies for genuine reasons. We carried out extensive simulation to explore the comparative performance of multivariate approach with most commonly used univariate inverse-variance weighted approach under random-effects assumption in various realistic meta-analytic scenarios of genetic association studies of correlated end points. We evaluated the performance with respect to relative mean bias percentage, and root mean square error (RMSE of the estimate and coverage probability of corresponding 95% confidence interval of the effect for each end point. Our simulation results suggest that multivariate approach performs similarly or better than univariate method when correlations between end points within or between studies are at least moderate and between-study variation is similar or larger than average within-study variation for meta-analyses of 10 or more genetic studies. Multivariate approach produces estimates with smaller bias and RMSE especially for the end point that has randomly or informatively missing summary data in some individual studies, when

  4. Statistical methods for elimination of guarantee-time bias in cohort studies: a simulation study

    Directory of Open Access Journals (Sweden)

    In Sung Cho

    2017-08-01

    Full Text Available Abstract Background Aspirin has been considered to be beneficial in preventing cardiovascular diseases and cancer. Several pharmaco-epidemiology cohort studies have shown protective effects of aspirin on diseases using various statistical methods, with the Cox regression model being the most commonly used approach. However, there are some inherent limitations to the conventional Cox regression approach such as guarantee-time bias, resulting in an overestimation of the drug effect. To overcome such limitations, alternative approaches, such as the time-dependent Cox model and landmark methods have been proposed. This study aimed to compare the performance of three methods: Cox regression, time-dependent Cox model and landmark method with different landmark times in order to address the problem of guarantee-time bias. Methods Through statistical modeling and simulation studies, the performance of the above three methods were assessed in terms of type I error, bias, power, and mean squared error (MSE. In addition, the three statistical approaches were applied to a real data example from the Korean National Health Insurance Database. Effect of cumulative rosiglitazone dose on the risk of hepatocellular carcinoma was used as an example for illustration. Results In the simulated data, time-dependent Cox regression outperformed the landmark method in terms of bias and mean squared error but the type I error rates were similar. The results from real-data example showed the same patterns as the simulation findings. Conclusions While both time-dependent Cox regression model and landmark analysis are useful in resolving the problem of guarantee-time bias, time-dependent Cox regression is the most appropriate method for analyzing cumulative dose effects in pharmaco-epidemiological studies.

  5. Interactions in charged colloidal suspensions: A molecular dynamics simulation study

    Science.gov (United States)

    Padidela, Uday Kumar; Behera, Raghu Nath

    2017-07-01

    Colloidal suspensions are extensively used in everyday life and find several applications in the pharmaceutical, chemical, food industries, etc. We present the classical molecular dynamics simulation results of the structural and transport properties of charged colloidal suspensions as a function of its size, charge and concentration. The system is viewed as a two-component (colloids and counterions) primitive model consisting of spherical colloid particle (macroion) and the counterions (micro-particles), which are treated explicitly. The solvent is treated as dielectric continuum. A systematic trend in the radial distribution functions g(r), potential of mean force W(r), different thermodynamic properties and diffusion coefficients is obtained as a function of colloid charge, size and concentration. An attractive minimum in W(r) is obtained at short interparticle distance.

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

    Science.gov (United States)

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

    2016-11-01

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

  7. Updated Simulation Studies of Damage Limit of LHC Tertiary Collimators

    CERN Document Server

    AUTHOR|(CDS)2085459; Bertarelli, Alessandro; Bruce, Roderik; Carra, Federico; Cerutti, Francesco; Gradassi, Paolo; Lechner, Anton; Redaelli, Stefano; Skordis, Eleftherios

    2015-01-01

    The tertiary collimators (TCTs) in the LHC, installed in front of the experiments, in standard operation intercept fractions of 10−3 halo particles. However, they risk to be hit by high-intensity primary beams in case of asynchronous beam dump. TCT damage thresholds were initially inferred from results of destructive tests on a TCT jaw, supported by numerical simulations, assuming simplified impact scenarios with one single bunch hitting the jaw with a given impact parameter. In this paper, more realistic failure conditions, including a train of bunches and taking into account the full collimation hierarchy, are used to derive updated damage limits. The results are used to update the margins in the collimation hierarchy and could thus potentially have an influence on the LHC performance.

  8. Design and Study of Cognitive Network Physical Layer Simulation Platform

    Directory of Open Access Journals (Sweden)

    Yongli An

    2014-01-01

    Full Text Available Cognitive radio technology has received wide attention for its ability to sense and use idle frequency. IEEE 802.22 WRAN, the first to follow the standard in cognitive radio technology, is featured by spectrum sensing and wireless data transmission. As far as wireless transmission is concerned, the availability and implementation of a mature and robust physical layer algorithm are essential to high performance. For the physical layer of WRAN using OFDMA technology, this paper proposes a synchronization algorithm and at the same time provides a public platform for the improvement and verification of that new algorithm. The simulation results show that the performance of the platform is highly close to the theoretical value.

  9. Czochralski silicon crystal growth: Modeling and simulation study

    Science.gov (United States)

    Javidi, Massoud

    Czochralski (CZ) crystal growth process is a widely used technique in the manufacturing of silicon crystals and other semiconductor materials such as germanium (Ge) and gallium arsenide (GaAs). The ultimate goal for the Integrated Circuit (IC) industry is to have the highest quality substrate. There is a huge interest to manipulate the thermal field in both the melt and crystal and control the melt convection and crystal-annealing rate in order to reduce growth striations, impurity and dopant inhomogeneity concentrations, excess point defects generation at interface, and micro defects nucleation and growth within the growing crystal. The objective of this investigation has been to facilitate and spearhead the development of a simple/efficient simulation tool for the accurate prediction of global thermal and flow fields and the melt-crystal interface position in the CZ process. The numerical algorithm employs a rectangular (fixed or non-uniform) mesh for enhanced computational efficiency and an enthalpy-based technique for interface tracking. Turbulent flow in the melt is accounted for by utilizing a K-ε model. Radiative heat transfer is modeled in a lumped parameter sense without appreciably compromising on solution accuracy to further allow for CPU times savings. The simulation tool is validated in a number of benchmark flows such as Wheeler's problem. For the CZ crystal growth process, an entire growth cycle has been computed and reliable predictions for the evolution of interface position, and flow/thermal field characteristics have been obtained. The enhanced CPU efficiency of the approach developed here could help integrate it into on-line control strategies.

  10. DWPF SIMULANT CPC STUDIES FOR SB7B

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, D.

    2011-11-01

    Lab-scale DWPF simulations of Sludge Batch 7b (SB7b) processing were performed. Testing was performed at the Savannah River National Laboratory - Aiken County Technology Laboratory (SRNL-ACTL). The primary goal of the simulations was to define a likely operating window for acid stoichiometry for the DWPF Sludge Receipt and Adjustment Tank (SRAT). In addition, the testing established conditions for the SRNL Shielded Cells qualification simulation of SB7b-Tank 40 blend, supported validation of the current glass redox model, and validated the coupled process flowsheet at the nominal acid stoichiometry. An acid window of 105-140% by the Koopman minimum acid (KMA) equation (107-142% DWPF Hsu equation) worked for the sludge-only flowsheet. Nitrite was present in the SRAT product for the 105% KMA run at 366 mg/kg, while SME cycle hydrogen reached 94% of the DWPF Slurry Mix Evaporator (SME) cycle limit in the 140% KMA run. The window was determined for sludge with added caustic (0.28M additional base, or roughly 12,000 gallons 50% NaOH to 820,000 gallons waste slurry). A suitable processing window appears to be 107-130% DWPF acid equation for sludge-only processing allowing some conservatism for the mapping of lab-scale simulant data to full-scale real waste processing including potentially non-conservative noble metal and mercury concentrations. This window should be usable with or without the addition of up to 7,000 gallons of caustic to the batch. The window could potentially be wider if caustic is not added to SB7b. It is recommended that DWPF begin processing SB7b at 115% stoichiometry using the current DWPF equation. The factor could be increased if necessary, but changes should be made with caution and in small increments. DWPF should not concentrate past 48 wt.% total solids in the SME cycle if moderate hydrogen generation is occurring simultaneously. The coupled flowsheet simulation made more hydrogen in the SRAT and SME cycles than the sludge-only run with the

  11. Analysis of nanowire transistor based nitrogen dioxide gas sensor – A simulation study

    Directory of Open Access Journals (Sweden)

    Gaurav Saxena

    2015-06-01

    Full Text Available Sensors sensitivity, selectivity and stability has always been a prime design concern for gas sensors designers. Modeling and simulation of gas sensors aids the designers in improving their performance. In this paper, different routes for the modeling and simulation of a semiconducting gas sensor is presented. Subsequently, by employing one of the route, the response of Zinc Oxide nanowire transistor towards nitrogen dioxide ambient is simulated. In addition to the sensing mechanism, simulation study of gas species desorption by applying a recovery voltage is also presented.

  12. Study of influence of buildup factor form on simulated radiographic image

    Directory of Open Access Journals (Sweden)

    Marinković Predrag

    2009-01-01

    Full Text Available The objective of the study presented in this paper is the analysis of influence of different buildup factor forms on a simulated radiographic image. Simulated radiographic images are obtained by means of the ray-tracing technique. Scattered photons are modelled using the generally accepted geometric progression form, linear form and tabulated data of buildup factors. Simulated images were compared to the reference results obtained by Monte Carlo calculation. The best agreement to Monte Carlo simulated images is achieved for the geometric progression form of buildup factor.

  13. Simulation of traumatic brain injury symptoms on the Personality Assessment Inventory: an analogue study.

    Science.gov (United States)

    Keiski, Michelle A; Shore, Douglas L; Hamilton, Joanna M; Malec, James F

    2015-04-01

    The purpose of this study was to characterize the operating characteristics of the Personality Assessment Inventory (PAI) validity scales in distinguishing simulators feigning symptoms of traumatic brain injury (TBI) while completing the PAI (n = 84) from a clinical sample of patients with TBI who achieved adequate scores on performance validity tests (n = 112). The simulators were divided into two groups: (a) Specific Simulators feigning cognitive and somatic symptoms only or (b) Global Simulators feigning cognitive, somatic, and psychiatric symptoms. The PAI overreporting scales were indeed sensitive to the simulation of TBI symptoms in this analogue design. However, these scales were less sensitive to the feigning of somatic and cognitive TBI symptoms than the feigning of a broad range of cognitive, somatic, and emotional symptoms often associated with TBI. The relationships of TBI simulation to consistency and underreporting scales are also explored. © The Author(s) 2014.

  14. Simulation study of acoustic wave propagation in ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Mohite-Patil, T.B.; Saran, A.K.; Sawant, S.R.; Chile, R.H.; Mohite-Patil, T.T.

    . SIMULATION MODEL s o u n d s p e e d s b y d i f f . m e t h o d s s i m o u t s s p T o W o r k s p a ce 1 s i m o u t s s p e r r T o W o r k s p a ce 1483 S S P M C E R R M C E R R G R E R R C O P E R R C H E N E R R F R G R S S P M C S S P G R... S S P C O P S S P C H E N O B S S P E E D S S P G R F R T S SS D P s s pm c Errm c s s pgr Errgr s s pc op Errc op s s pc hen Errc hen s s pgrf r Errf rgr M a i n s o u n d s p e e d m o d e l [ m D ] F r o m W o r k s p a ce 2 [ m S ] F r o m W o...

  15. Computer simulation studies of confined liquid-crystal films

    Science.gov (United States)

    Wall, Greg D.; Cleaver, Douglas J.

    1997-10-01

    In this paper we present results from molecular dynamics simulations performed using a system of Gay-Berne particles confined between two substrates in a slab geometry. We use a nonseparable anisotropic molecule-substrate interaction potential and investigate weak and moderate molecule-substrate coupling strengths. We find that for both coupling strengths a well-defined, tilted molecular layer forms at each wall and that the pretilt angle and layer density are only weakly dependent on temperature as the central region is cooled through isotropiclike and nematiclike regions. The orientationally ordered fluid formed at the center of the film is tilted in sympathy with the surface layers. At low temperatures, however, where the central region adopts a layered arrangement, a sharp change is observed in the pretilt angle. This transition is more marked in the weak-coupling system where the high-temperature tilted surface layers adopt an approximately planar arrangement at low temperatures and the system resembles a bookshelf-geometry smectic film. In the moderate-coupling system, the surface layers maintain some tilt in the presence of the layered central region, leading to a smectic-stripe phase arrangement.

  16. Asymmetric switching in a homodimeric ABC transporter: a simulation study.

    Directory of Open Access Journals (Sweden)

    Jussi Aittoniemi

    2010-04-01

    Full Text Available ABC transporters are a large family of membrane proteins involved in a variety of cellular processes, including multidrug and tumor resistance and ion channel regulation. Advances in the structural and functional understanding of ABC transporters have revealed that hydrolysis at the two canonical nucleotide-binding sites (NBSs is co-operative and non-simultaneous. A conserved core architecture of bacterial and eukaryotic ABC exporters has been established, as exemplified by the crystal structure of the homodimeric multidrug exporter Sav1866. Currently, it is unclear how sequential ATP hydrolysis arises in a symmetric homodimeric transporter, since it implies at least transient asymmetry at the NBSs. We show by molecular dynamics simulation that the initially symmetric structure of Sav1866 readily undergoes asymmetric transitions at its NBSs in a pre-hydrolytic nucleotide configuration. MgATP-binding residues and a network of charged residues at the dimer interface are shown to form a sequence of putative molecular switches that allow ATP hydrolysis only at one NBS. We extend our findings to eukaryotic ABC exporters which often consist of two non-identical half-transporters, frequently with degeneracy substitutions at one of their two NBSs. Interestingly, many residues involved in asymmetric conformational switching in Sav1866 are substituted in degenerate eukaryotic NBS. This finding strengthens recent suggestions that the interplay of a consensus and a degenerate NBS in eukaroytic ABC proteins pre-determines the sequence of hydrolysis at the two NBSs.

  17. Simulation of fruit pallet movement in the port of Durban: A case study

    African Journals Online (AJOL)

    . Table 1: Output parameters estimated in the simulation study. The following scenarios were simulated, namely (I) the effect of an increase in fruit exported through the port and (II) the effect of an investment in additional equipment. This paper ...

  18. Is energy expenditure taken into account in human sub-maximal jumping? - a simulation study

    NARCIS (Netherlands)

    Vanrenterghem, J.; Bobbert, M.F.; Casius, L.J.R.; de Clercq, D.

    2008-01-01

    This paper presents a simulation study that was conducted to investigate whether the stereotyped motion pattern observed in human sub-maximal jumping can be interpreted from the perspective of energy expenditure. Human sub-maximal vertical countermovement jumps were compared to jumps simulated with

  19. Learning nursing through simulation: A case study approach towards an expansive model of learning.

    Science.gov (United States)

    Berragan, Liz

    2014-08-01

    This study explores the impact of simulation upon learning for undergraduate nursing students. The study objectives were (a) to explore the experiences of participating in simulation education for a small group of student nurses; and (b) to explore learning through simulation from the perspectives of the nursing students, the nurse educators and the nurse mentors. Conducted as a small-scale narrative case study, it tells the unique stories of a small number of undergraduate nursing students, nurse mentors and nurse educators and explores their experiences of learning through simulation. Data analysis through progressive focusing revealed that the nurse educators viewed simulation as a means of helping students to learn to be nurses, whilst, the nurse mentors suggested that simulation helped them to determine nursing potential. The students' narratives showed that they approached simulation learning in different ways resulting in a range of outcomes: those who were successfully becoming nurses, those who were struggling or working hard to become nurses and those who were not becoming nurses. Theories of professional practice learning and activity theory present an opportunity to articulate and theorise the learning inherent in simulation activities. They recognise the links between learning and the environment of work and highlight the possibilities for learning to inspire change and innovation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Assessment of SPM in perfusion brain SPECT studies. A numerical simulation study using bootstrap resampling methods.

    Science.gov (United States)

    Pareto, Deborah; Aguiar, Pablo; Pavía, Javier; Gispert, Juan Domingo; Cot, Albert; Falcón, Carles; Benabarre, Antoni; Lomeña, Francisco; Vieta, Eduard; Ros, Domènec

    2008-07-01

    Statistical parametric mapping (SPM) has become the technique of choice to statistically evaluate positron emission tomography (PET), functional magnetic resonance imaging (fMRI), and single photon emission computed tomography (SPECT) functional brain studies. Nevertheless, only a few methodological studies have been carried out to assess the performance of SPM in SPECT. The aim of this paper was to study the performance of SPM in detecting changes in regional cerebral blood flow (rCBF) in hypo- and hyperperfused areas in brain SPECT studies. The paper seeks to determine the relationship between the group size and the rCBF changes, and the influence of the correction for degradations. The assessment was carried out using simulated brain SPECT studies. Projections were obtained with Monte Carlo techniques, and a fan-beam collimator was considered in the simulation process. Reconstruction was performed by using the ordered subsets expectation maximization (OSEM) algorithm with and without compensation for attenuation, scattering, and spatial variant collimator response. Significance probability maps were obtained with SPM2 by using a one-tailed two-sample t-test. A bootstrap resampling approach was used to determine the sample size for SPM to detect the between-group differences. Our findings show that the correction for degradations results in a diminution of the sample size, which is more significant for small regions and low-activation factors. Differences in sample size were found between hypo- and hyperperfusion. These differences were larger for small regions and low-activation factors, and when no corrections were included in the reconstruction algorithm.

  1. A new strategy in neurocritical care nurse continuing stroke education: A hybrid simulation pilot study.

    Science.gov (United States)

    Newey, Christopher Ryan; Bell, Robert; Burks, Melody; Nattanmai, Premkumar

    2017-05-01

    High-fidelity simulation is frequently utilized in medical education. Its use in the neurosciences is limited by the inherent limitations of the manikin to simulate neurological changes. We report here the use of a hybrid simulation - a combination of lecture and high-fidelity manikin - in the education of neurosciences nurses, involved in care of neurocritical care patients. Neurosciences nurses from at the University of Missouri, Columbia, MO, USA, which is an academic, tertiary-care medical center participated in the simulation during Spring of 2016. The simulation involved a patient presenting with acute intracerebral hemorrhage (ICH) who neurologically deteriorated to brain death. Pre- and post-simulation questionnaires were administered using a questionnaire with five-point Liker scale. Seventy-two responses were returned. The majority had 0-5 years of nursing experience with 83.8% having prior critical care experience. Pre-simulation, the majority of nurses (85.7%) agreed or strongly agreed with managing patients with ICH. When the responses of "agree" were compared to "strongly agree", a significant improvement (p<0.001) in all responses except confidence in speaking with other healthcare providers was found. Nurses reported significant improvement in understanding and managing patients with acute ICH and neurological deterioration after participating in a neurocritical care hybrid simulation. This study shows the benefit of using hybrid simulation in the education of neurocritical care nurses.

  2. Quality indicators for the design and implementation of simulation experiences: a Delphi study.

    Science.gov (United States)

    Arthur, Carol; Levett-Jones, Tracy; Kable, Ashley

    2013-11-01

    Simulation is widely used in nursing education. Previous studies have examined the impact of simulation on the acquisition of psychomotor skills, knowledge, critical thinking and non-technical skills such as teamwork. Challenges associated with the integration of simulation into nursing curricula have also been examined, however only limited research addresses the most effective simulation design and teaching strategies for quality educational outcomes. This paper reports a Delphi study that synthesises expert opinion on the pedagogical principles and teaching strategies that are indicative of quality in simulation based learning activities. The resultant set of Quality Indicator Statements is presented and opportunities for application and further research are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Recovery of information from multiple imputation: a simulation study

    Directory of Open Access Journals (Sweden)

    Lee Katherine J

    2012-06-01

    Full Text Available Abstract Background Multiple imputation is becoming increasingly popular for handling missing data. However, it is often implemented without adequate consideration of whether it offers any advantage over complete case analysis for the research question of interest, or whether potential gains may be offset by bias from a poorly fitting imputation model, particularly as the amount of missing data increases. Methods Simulated datasets (n = 1000 drawn from a synthetic population were used to explore information recovery from multiple imputation in estimating the coefficient of a binary exposure variable when various proportions of data (10-90% were set missing at random in a highly-skewed continuous covariate or in the binary exposure. Imputation was performed using multivariate normal imputation (MVNI, with a simple or zero-skewness log transformation to manage non-normality. Bias, precision, mean-squared error and coverage for a set of regression parameter estimates were compared between multiple imputation and complete case analyses. Results For missingness in the continuous covariate, multiple imputation produced less bias and greater precision for the effect of the binary exposure variable, compared with complete case analysis, with larger gains in precision with more missing data. However, even with only moderate missingness, large bias and substantial under-coverage were apparent in estimating the continuous covariate’s effect when skewness was not adequately addressed. For missingness in the binary covariate, all estimates had negligible bias but gains in precision from multiple imputation were minimal, particularly for the coefficient of the binary exposure. Conclusions Although multiple imputation can be useful if covariates required for confounding adjustment are missing, benefits are likely to be minimal when data are missing in the exposure variable of interest. Furthermore, when there are large amounts of missingness, multiple

  4. Case Study of a Global Simulation in French as a Foreign Language ...

    African Journals Online (AJOL)

    Case Study of a Global Simulation in French as a Foreign Language with Beginner Level Learners at the University Of Namibia: A Search for an Authentic Language and Culture Exposure in an African Anglophone Country.

  5. Treatment of pediatric diarrhea: a simulated client study at private pharmacies of Ujjain, Madhya Pradesh, India

    National Research Council Canada - National Science Library

    Diwan, Vishal; Sabde, Yogesh D; Byström, Emma; De Costa, Ayesha

    2015-01-01

    .... The present study used simulated client methodology to assess the actual dispensing practices for patients with pediatric diarrhea at private pharmacies in an urban setting of an Indian province...

  6. Study on Tensile Properties of Nanoreinforced Epoxy Polymer: Macroscopic Experiments and Nanoscale FEM Simulation Prediction

    Directory of Open Access Journals (Sweden)

    Zhenqing Wang

    2013-01-01

    Full Text Available The effect of nanosilica contents on mechanical properties of the epoxy matrix with some nanoparticle aggregations was studied in macroscopic experiments and nanoscale simulation, particularly with regard to the effective modulus and ultimate stress. Three analytical models were used to obtain the effective elastic modulus of nanoparticle-reinforced composites. Based on Monte-Carlo method, the special program for the automatic generation of 2D random distribution particles without overlapping was developed for nanocomposite modeling. Weight fractions of nanoparticles were converted to volume fractions, in order to coordinate the content unit in the simulation. In numerical analysis, the weak interface strengthening and toughening mechanism was adopted. Virtual crack closure technique (VCCT and extended finite element method (XFEM were used to simulate phenomena of nanoparticle debonding and matrix crack growth. Experimental and simulation results show a good agreement with each other. By way of simulation, the weak interface toughening and strengthening mechanism of nanocomposites is confirmed.

  7. Experimental and Simulative Study on Accumulator Function in The Process of Wave Energy Conversion

    Directory of Open Access Journals (Sweden)

    Zhang Wei

    2016-09-01

    Full Text Available In this paper, a floating-buoy wave energy converter using hydrostatic transmission system is studied. The entire work progress of wave energy power generation device is introduced, and the hydraulic transmission principles are emphasized through the simulation to verify the feasibility of design principle of hydraulic transmission system. The mathematical model of the accumulator is established and applied in the AMEsim simulation. The simulation results show that the accumulator plays an important role in the wave power hydraulic transmission system and that the correct configuration of accumulator parameters can improve the rapidity and stability of the system work. Experimental results are compared with the simulation results to validate the correctness of the simulation results. This would provide a valuable reference to the optimal design of wave power generation.

  8. Numerical Study of Aerodynamic Characteristics of a Symmetric NACA Section with Simulated Ice Shapes

    Science.gov (United States)

    Tabatabaei, N.; Cervantes, M. J.; Trivedi, C.; Aidanpää, Jan-Olof

    2016-09-01

    To develop a numerical model of icing on wind turbine blades, a CFD simulation was conducted to investigate the effect of critical ice accretions on the aerodynamic characteristics of a 0.610 m chord NACA 0011 airfoil section. Aerodynamic performance coefficients and pressure profile were calculated and compared with the available measurements for a chord Reynolds number of 1.83x106. Ice shapes were simulated with flat plates (spoiler-ice) extending along the span of the wing. Lift, drag, and pressure coefficients were calculated in zero angle of attack through the steady state and transient simulations. Different approaches of numerical studies have been applied to investigate the icing conditions on the blades. The simulated separated flow over the sharp spoilers is challenging and can be seen as a worst test case for validation. It allows determining a reliable strategy to simulate real ice shapes [1] for which the detailed validation cannot easily be provided.

  9. STUDY AND NUMERICAL SIMULATION OF SOLAR SYSTEM FOR AIR HEATING

    Directory of Open Access Journals (Sweden)

    M. Ghodbane

    2016-01-01

    Full Text Available The use of solar energy in sunny countries, is an effective outil for compensate the lack in the energy, their benefits are not related only to its economic benefits but especially for the environmental protection, so we must find solutions to the problems of pollution. This work is a theoretical study of a solar flat plate collector ; air is used as the heat transfer fluid. In this study, we established in first step the calculation of solar radiation in various sites in Algeria (Adrar, El Oued, Bechar, Biskra and Tamanrasset. The second step is the parameters influence study of the sites and climate on the performance of our collector. The results obtained are encouraging for the use of this type in the heating in the winter, also it can be used in different kinds of drying.

  10. Fantasies of medical reality: an observational study of simulation-based medical education

    OpenAIRE

    Pelletier, C; Kneebone, R

    2015-01-01

    Medicine is increasingly taught in immersive simulated environments, to supplement the apprenticeship model of work-based learning. Clinical research on this educational practice focuses on its realism, defined as a property of simulation technology. We treat realism as a function of subjective but collectively organised perception and imbued with fantasy, which we define by drawing on Lacanian studies of virtual reality and workplace organisation. Data from an observational study of four sim...

  11. Simulation of complex data structures for planning of studies with focus on biomarker comparison

    Directory of Open Access Journals (Sweden)

    Andreas Schulz

    2017-06-01

    Full Text Available Abstract Background There are a growing number of observational studies that do not only focus on single biomarkers for predicting an outcome event, but address questions in a multivariable setting. For example, when quantifying the added value of new biomarkers in addition to established risk factors, the aim might be to rank several new markers with respect to their prediction performance. This makes it important to consider the marker correlation structure for planning such a study. Because of the complexity, a simulation approach may be required to adequately assess sample size or other aspects, such as the choice of a performance measure. Methods In a simulation study based on real data, we investigated how to generate covariates with realistic distributions and what generating model should be used for the outcome, aiming to determine the least amount of information and complexity needed to obtain realistic results. As a basis for the simulation a large epidemiological cohort study, the Gutenberg Health Study was used. The added value of markers was quantified and ranked in subsampling data sets of this population data, and simulation approaches were judged by the quality of the ranking. One of the evaluated approaches, the random forest, requires original data at the individual level. Therefore, also the effect of the size of a pilot study for random forest based simulation was investigated. Results We found that simple logistic regression models failed to adequately generate realistic data, even with extensions such as interaction terms or non-linear effects. The random forest approach was seen to be more appropriate for simulation of complex data structures. Pilot studies starting at about 250 observations were seen to provide a reasonable level of information for this approach. Conclusions We advise to avoid oversimplified regression models for simulation, in particular when focusing on multivariable research questions. More generally

  12. Simulation of complex data structures for planning of studies with focus on biomarker comparison.

    Science.gov (United States)

    Schulz, Andreas; Zöller, Daniela; Nickels, Stefan; Beutel, Manfred E; Blettner, Maria; Wild, Philipp S; Binder, Harald

    2017-06-13

    There are a growing number of observational studies that do not only focus on single biomarkers for predicting an outcome event, but address questions in a multivariable setting. For example, when quantifying the added value of new biomarkers in addition to established risk factors, the aim might be to rank several new markers with respect to their prediction performance. This makes it important to consider the marker correlation structure for planning such a study. Because of the complexity, a simulation approach may be required to adequately assess sample size or other aspects, such as the choice of a performance measure. In a simulation study based on real data, we investigated how to generate covariates with realistic distributions and what generating model should be used for the outcome, aiming to determine the least amount of information and complexity needed to obtain realistic results. As a basis for the simulation a large epidemiological cohort study, the Gutenberg Health Study was used. The added value of markers was quantified and ranked in subsampling data sets of this population data, and simulation approaches were judged by the quality of the ranking. One of the evaluated approaches, the random forest, requires original data at the individual level. Therefore, also the effect of the size of a pilot study for random forest based simulation was investigated. We found that simple logistic regression models failed to adequately generate realistic data, even with extensions such as interaction terms or non-linear effects. The random forest approach was seen to be more appropriate for simulation of complex data structures. Pilot studies starting at about 250 observations were seen to provide a reasonable level of information for this approach. We advise to avoid oversimplified regression models for simulation, in particular when focusing on multivariable research questions. More generally, a simulation should be based on real data for adequately reflecting

  13. A Theoretical Study of Subsurface Drainage Model Simulation of ...

    African Journals Online (AJOL)

    A three-dimensional variable-density groundwater flow model, the SEAWAT model, was used to assess the influence of subsurface drain spacing, evapotranspiration and irrigation water quality on salt concentration at the base of the root zone, leaching and drainage in salt affected irrigated land. The study was carried out ...

  14. Simulation Study Of Small Scale Jobshop | Ubani | Journal of ...

    African Journals Online (AJOL)

    This paper examines the impact of strategic change management on the performances of public transport in Osun State, Nigeria. It aimed at determining the role of leadership style in strategic change management; identify in factors that are influencing change process and actual performance of an organization. The study ...

  15. Study and numerical simulation of solar system for air heating ...

    African Journals Online (AJOL)

    The use of solar energy in sunny countries, is an effective outil for compensate the lack in the energy, their benefits are not related only to its economic benefits but especially for the environmental protection, so we must find solutions to the problems of pollution. This work is a theoretical study of a solar flat plate collector; air ...

  16. A study on the usefulness of high fidelity patient simulation in undergraduate medical education

    Directory of Open Access Journals (Sweden)

    Bikramjit Pal

    2018-01-01

    Full Text Available Introduction: Simulation is the imitation of the operation of a real-world process or system over time. Innovative simulation training solutions are now being used to train medical professionals in an attempt to reduce the number of safety concerns that have adverse effects on the patients. Objectives: (a To determine its usefulness as a teaching or learning tool for management of surgical emergencies, both in the short term and medium term by students’ perception. (b To plan future teaching methodology regarding hi-fidelity simulation based on the study outcomes and re-assessment of the current training modules. Methods: Quasi-experimental time series design with pretest-posttest interventional study. Quantitative data was analysed in terms of Mean, Standard Deviation and standard error of Mean. Statistical tests of significance like Repeated Measure of Analysis of Variance (ANOVA were used for comparisons. P value < 0.001 was considered to be statistically significant. Results: The students opined that the simulated sessions on high fidelity simulators had encouraged their active participation which was appropriate to their current level of learning. It helped them to think fast and the training sessions resembled a real life situation. The study showed that learning had progressively improved with each session of simulation with corresponding decrease in stress. Conclusion: Implementation of high fidelity simulation based learning in our Institute had been perceived favourably by a large number of students in enhancing their knowledge over time in management of trauma and surgical emergencies.

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

    Science.gov (United States)

    Goh, Yang Miang; Askar Ali, Mohamed Jawad

    2016-08-01

    One of the key challenges in improving construction safety and health is the management of safety behavior. From a system point of view, workers work unsafely due to system level issues such as poor safety culture, excessive production pressure, inadequate allocation of resources and time and lack of training. These systemic issues should be eradicated or minimized during planning. However, there is a lack of detailed planning tools to help managers assess the impact of their upstream decisions on worker safety behavior. Even though simulation had been used in construction planning, the review conducted in this study showed that construction safety management research had not been exploiting the potential of simulation techniques. Thus, a hybrid simulation framework is proposed to facilitate integration of safety management considerations into construction activity simulation. The hybrid framework consists of discrete event simulation (DES) as the core, but heterogeneous, interactive and intelligent (able to make decisions) agents replace traditional entities and resources. In addition, some of the cognitive processes and physiological aspects of agents are captured using system dynamics (SD) approach. The combination of DES, agent-based simulation (ABS) and SD allows a more "natural" representation of the complex dynamics in construction activities. The proposed hybrid framework was demonstrated using a hypothetical case study. In addition, due to the lack of application of factorial experiment approach in safety management simulation, the case study demonstrated sensitivity analysis and factorial experiment to guide future research. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. NMR Studies and Molecular Dynamic Simulation of Synthetic Dendritic Antigens

    Directory of Open Access Journals (Sweden)

    Ezequiel Perez-Inestrosa

    2011-09-01

    Full Text Available A series of synthetic benzylpenicillinoylated dendrimers has been prepared using up to 4th generation PAMAM dendrimers. These nanoconjugates, as nanosized Dendritic Antigens, are useful in the diagnostic evaluation of drug allergy due to specific molecular recognition with the Human Immunological System (IgE. The morphology and dimensions of the conjugates coupled to the orientation of the peripheral benzylpenicillin residues in the dendrimers may play key roles in such molecular recognition processes. Herein, the characterization and conformation of these structures are studied by a detailed analysis of 1D (1H and 13C NMR and 2D NMR (1H,1H-NOESY spectra. These dendrimers in explicit solvent were studied by the atomistic forcefield-based molecular dynamics. Structural properties such as shape, radius-of-gyration and distribution of the monomers will be discussed in relation to the experimental observations.

  19. Genetic Testing for Complex Diseases: a Simulation Study Perspective

    OpenAIRE

    Vinh, Nguyen Xuan

    2011-01-01

    It is widely recognized nowadays that complex diseases are caused by, amongst the others, multiple genetic factors. The recent advent of genome-wide association study (GWA) has triggered a wave of research aimed at discovering genetic factors underlying common complex diseases. While the number of reported susceptible genetic variants is increasing steadily, the application of such findings into diseases prognosis for the general population is still unclear, and there are doubts about whether...

  20. The Power of Phase I Studies to Detect Clinical Relevant QTc Prolongation: A Resampling Simulation Study

    Directory of Open Access Journals (Sweden)

    Georg Ferber

    2015-01-01

    Full Text Available Concentration-effect (CE models applied to early clinical QT data from healthy subjects are described in the latest E14 Q&A document as promising analysis to characterise QTc prolongation. The challenges faced if one attempts to replace a TQT study by thorough ECG assessments in Phase I based on CE models are the assurance to obtain sufficient power and the establishment of a substitute for the positive control to show assay sensitivity providing protection against false negatives. To demonstrate that CE models in small studies can reliably predict the absence of an effect on QTc, we investigated the role of some key design features in the power of the analysis. Specifically, the form of the CE model, inclusion of subjects on placebo, and sparse sampling on the performance and power of this analysis were investigated. In this study, the simulations conducted by subsampling subjects from 3 different TQT studies showed that CE model with a treatment effect can be used to exclude small QTc effects. The number of placebo subjects was also shown to increase the power to detect an inactive drug preventing false positives while an effect can be underestimated if time points around tmax are missed.

  1. Mechanical Response Study of Collagen by means of Molecular Simulation

    Science.gov (United States)

    in't Veld, Pieter J.

    2005-03-01

    We developed a coarse-grained model to study mechanical behavior of collagen fibrils as a function of their degree of cross-linking. A collagen molecule is represented by Lennard-Jones beads, which intra-molecularly are connected through harmonic springs on both bond length and angle. In this model each bead represents a helical turn in a collagen molecule. Triple-helical collagen molecules, which are 300 nm long, are packed within fibrils in a staggered fashion with an axial spacing of 67 nm in the absence of a load on the tendon. We treat the outer layer or shell different from the core by assuming the shell has the maximum amount of available cross-links. The core has a variable amount of cross-links by allowing cross-link formation and breakage depending on a reaction-type criterion. We study the stress-strain behavior of a single fibril through tensile deformation along the principal axis and a three-point bend perpendicular to the principal axis.

  2. Ceiling Fires Studied to Simulate Low-Gravity Fires

    Science.gov (United States)

    Olson, Sandra L.

    2001-01-01

    A unique new way to study low-gravity flames in normal gravity has been developed. To study flame structure and extinction characteristics in low-stretch environments, a normal gravity low-stretch diffusion flame was generated using a cylindrical PMMA sample of varying large radii, as shown in the photograph. These experiments have demonstrated that low-gravity flame characteristics can be generated in normal gravity through the proper use of scaling. On the basis of this work, it is feasible to apply this concept toward the development of an Earth-bound method of evaluating material flammability in various gravitational environments from normal gravity to microgravity, including the effects of partial gravity low-stretch rates such as those found on the Moon (1/6g) or Mars (1/3g). During these experiments, the surface regression rates for PMMA were measured for the first time over the full range of flammability in air, from blowoff at high stretch, to quenching at low stretch, as plotted in the graph. The solid line drawn through the central portion of the data (3

  3. Management of Nitrate m Groundwater: A Simulation Study

    Directory of Open Access Journals (Sweden)

    M. Ahmed

    2001-01-01

    Full Text Available Agriculture may cause nitrate and other chemicals to enter into groundwater systems. Nitrate in drinking water is considered a health hazard. A study was conducted to assess the extent of nitrate pollution of groundwater caused by agriculture and to evaluate the possibility of using the LEACHN model to manage nitrate entry into groundwater of agricultural areas of Al-Batinah, which is the most important agricultural region of Oman. Groundwater samples were collected and analyzed to assess the problem and to detect possible trends. Soil sampling and analyses were done to demonstrate the difference in the nitrate concentration in agricultural and non-agricultural soils. A questionnaire survey was conducted to gather information on agricultural practices, fertilizer input, and other possible sources of nitrate pollution. Results from the study show that 23% of groundwater samples have a concentration of nitrate-N concentration of 10 mg/l and 34% samples exceed 8 mg/l. Agricultural soils have higher levels of nitrate compared to non- agricultural soils. Results also demonstrate that nitrate levels in groundwater in Al-Batinah are rising. Application of the ‘LEACHN’ model demonstrated its suitability for use as a management tool to reduce nitrate leaching to groundwater by controlling fertilizer and water input.

  4. A STOCHASTIC SIMULATION STUDY ON SPECIATION BY SEXUAL SELECTION.

    Science.gov (United States)

    Wu, Chung-I

    1985-01-01

    A two-locus multi-allele sexual isolation model incorporating mutation and genetic drift which was first proposed by Nei et al. (1983) is studied here. One locus controls the male mating character, and the other controls female receptivity. All females are assumed to have equal mating success. Therefore, the frequencies of female receptivity alleles are changed by mutation, drift, and hitchhiking with male character alleles. Without hitchhiking, development of sexual isolation between allopatric populations proceeds faster in smaller populations, as expected. The hitchhiking effect, by triggering the mutual reinforcement of mating behavior of both sexes (or the runaway process, Fisher [1958]), speeds up the evolution of sexual isolation significantly. For populations with 2Nv ≤ 0.2 (N = population size, ν = mutation rate), the rates of divergence all approach the maximum possible rate. Sympatric sexual isolation develops quite frequently if two favorable conditions are met: 1) There is no selection on female phenotype (except in some limited cases), and 2) The population size is large enough to carry several female receptivity alleles. Because of stochastic factors, these alleles may lead to the formation of two discrete groups of females, each group receptive to males of different mating characters. The formation of sympatric sexually-isolated groups is also aided significantly, at the incipient stage, by the runaway process. © 1985 The Society for the Study of Evolution.

  5. A study and simulation for the sympathetic phenomenon in transformers

    Energy Technology Data Exchange (ETDEWEB)

    Ramezani, B.; Keivani, H. [Islamic Azad Univ., Kazeroon (Iran, Islamic Republic of). College of Electrical Engineering; Heydari, H. [Iran Univ., Tehran (Iran, Islamic Republic of). College of Engineering

    2005-07-01

    This paper examined the inrush current phenomena in parallel-connected transformers and transformer banks at substations. The study used analytical expressions for the nonlinear magnetization curves of the transformers. Solutions to the differential equations were then used to determine the waveforms of the currents and fluxes of each transformer as well as the total substation current. Parameters influencing the expected magnitudes of strongly distorted waveforms were also investigated. The use of shunt capacitors in correcting existing power factor was also explored. Results showed that inrush current were more dangerous if switching occurred at the supply voltage zero crossing. The transformer exhibited an unsymmetrical magnetization loop when compared with the switching at voltage peaks. The high harmonic content of the current was evident at any switching time point. Increases in source impedance resulted in reduced voltages at the transformer terminals. Increased source parameters resulted in increased interactions between the transformers. It was suggested that results of the study can be used to develop protective measures for transformers and substations. 6 refs., 15 figs.

  6. Modelling and Simulation of TCPAR for Power System Flow Studies

    Directory of Open Access Journals (Sweden)

    Narimen Lahaçani AOUZELLAG

    2012-12-01

    Full Text Available In this paper, the modelling of Thyristor Controlled Phase Angle Regulator ‘TCPAR’ for power flow studies and the role of that modelling in the study of Flexible Alternating Current Transmission Systems ‘FACTS’ for power flow control are discussed. In order to investigate the impact of TCPAR on power systems effectively, it is essential to formulate a correct and appropriate model for it. The TCPAR, thus, makes it possible to increase or decrease the power forwarded in the line where it is inserted in a considerable way, which makes of it an ideal tool for this kind of use. Knowing that the TCPAR does not inject any active power, it offers a good solution with a less consumption. One of the adverse effects of the TCPAR is the voltage drop which it causes in the network although it is not significant. To solve this disadvantage, it is enough to introduce a Static VAR Compensator ‘SVC’ into the electrical network which will compensate the voltages fall and will bring them back to an acceptable level.

  7. Simulation of breast compression in mammography using finite element analysis: A preliminary study

    Science.gov (United States)

    Liu, Yan-Lin; Liu, Pei-Yuan; Huang, Mei-Lan; Hsu, Jui-Ting; Han, Ruo-Ping; Wu, Jay

    2017-11-01

    Adequate compression during mammography lowers the absorbed dose in the breast and improves the image quality. The compressed breast thickness (CBT) is affected by various factors, such as breast volume, glandularity, and compression force. In this study, we used the finite element analysis to simulate breast compression and deformation and validated the simulated CBT with clinical mammography results. Image data from ten subjects who had undergone mammography screening and breast magnetic resonance imaging (MRI) were collected, and their breast models were created according to the MR images. The non-linear tissue deformation under 10-16 daN in the cranial-caudal direction was simulated. When the clinical compression force was used, the simulated CBT ranged from 2.34 to 5.90 cm. The absolute difference between the simulated CBT and the clinically measured CBT ranged from 0.5 to 7.1 mm. The simulated CBT had a strong positive linear relationship to breast volume and a weak negative correlation to glandularity. The average simulated CBT under 10, 12, 14, and 16 daN was 5.68, 5.12, 4.67, and 4.25 cm, respectively. Through this study, the relationships between CBT, breast volume, glandularity, and compression force are provided for use in clinical mammography.

  8. DIF Analysis with Multilevel Data: A Simulation Study Using the Latent Variable Approach

    Science.gov (United States)

    Jin, Ying; Eason, Hershel

    2016-01-01

    The effects of mean ability difference (MAD) and short tests on the performance of various DIF methods have been studied extensively in previous simulation studies. Their effects, however, have not been studied under multilevel data structure. MAD was frequently observed in large-scale cross-country comparison studies where the primary sampling…

  9. Enhancing Clinical Reasoning Through Simulation Debriefing: A Multisite Study.

    Science.gov (United States)

    Forneris, Susan G; Neal, Diana O; Tiffany, Jone; Kuehn, Mary Beth; Meyer, Heidi M; Blazovich, Linda M; Holland, Ann E; Smerillo, Melanie

    2015-01-01

    The aim of this research was to replicate Dreifuerst's 2012 findings of enhanced clinical reasoning scores using a structured debriefing: Debriefing for Meaningful Learning (DML). The direct effect of debriefing on clinical reasoning is not well studied. The nursing education literature supports debriefing as a reflective dialogue necessary to enhance clinical reasoning. A quasi-experimental, pretest-posttest, repeated measure research design was used to evaluate nursing students' clinical reasoning using the Health Sciences Reasoning Test (HSRT). The change in HSRT mean scores was determined to be significant for the intervention group at the .05 level and insignificant for the control group. The change in HSRT mean scores between the intervention and control groups was determined to be significant at the .10 level. Nursing students who had the DML debriefing scored significantly higher in their clinical reasoning than nursing students who had usual and customary debriefing.

  10. Experimental and simulated study of a composite structure metamaterial absorber

    Science.gov (United States)

    Li, Shengyong; Ai, Xiaochuan; Wu, Ronghua; Chen, Jiajun

    2017-11-01

    In this paper, a high performance metamaterial absorber is designed and experimental studied. Measured results indicate that a perfect absorption band and a short-wavelength absorption peak are achieved in the near-infrared spectrum. Current strength distributions reveal that the absorption band is excited by the cavity resonance. And electric field distributions show that the short-wavelength absorption peak is excited by the horizontal coupled of localized surface plasmon (LSP) modes near hole edges. On the one hand, the absorption property of the measured metamaterial absorber can be enhanced through optimizing the structural parameters (a, w, and H). On the other hand, the absorption property is sensitive to the change of refractive index of environmental medias. A sensing scheme is proposed for refractive index detecting based on the figure of merit (FOM) value. Measured results indicate that the proposed sensing scheme can achieve high FOM value with different environmental medias (water, glucose solution).

  11. Numerical simulation studies for optical properties of biomaterials

    Science.gov (United States)

    Krasnikov, I.; Seteikin, A.

    2016-11-01

    Biophotonics involves understanding how light interacts with biological matter, from molecules and cells, to tissues and even whole organisms. Light can be used to probe biomolecular events, such as gene expression and protein-protein interaction, with impressively high sensitivity and specificity. The spatial and temporal distribution of biochemical constituents can also be visualized with light and, thus, the corresponding physiological dynamics in living cells, tissues, and organisms in real time. Computer-based Monte Carlo (MC) models of light transport in turbid media take a different approach. In this paper, the optical and structural properties of biomaterials discussed. We explain the numerical simulationmethod used for studying the optical properties of biomaterials. Applications of the Monte-Carlo method in photodynamic therapy, skin tissue optics, and bioimaging described.

  12. Modeling and simulation of queuing system for customer service improvement: A case study

    Science.gov (United States)

    Xian, Tan Chai; Hong, Chai Weng; Hawari, Nurul Nazihah

    2016-10-01

    This study aims to develop a queuing model at UniMall by using discrete event simulation approach in analyzing the service performance that affects customer satisfaction. The performance measures that considered in this model are such as the average time in system, the total number of student served, the number of student in waiting queue, the waiting time in queue as well as the maximum length of buffer. ARENA simulation software is used to develop a simulation model and the output is analyzed. Based on the analysis of output, it is recommended that management of UniMall consider introducing shifts and adding another payment counter in the morning.

  13. Eighteenth Workshop on Recent Developments in Computer Simulation Studies in Condensed Matter Physics

    CERN Document Server

    Landau, David P; Schüttler, Heinz-Bernd; Computer Simulation Studies in Condensed-Matter Physics XVIII

    2006-01-01

    This volume represents a "status report" emanating from presentations made during the 18th Annual Workshop on Computer Simulations Studies in Condensed Matter Physics at the Center for Simulational Physics at the University of Georgia in March 2005. It provides a broad overview of the most recent advances in the field, spanning the range from statistical physics to soft condensed matter and biological systems. Results on nanostructures and materials are included as are several descriptions of advances in quantum simulations and quantum computing as well as.methodological advances.

  14. Numerical simulation and parametric study of UOE pipe forming process

    Science.gov (United States)

    Ren, Qiang; Zou, Tian-xia; Ji, Zong-chen; Li, Da-yong; Peng, Ying-hong; Han, Jian-zeng; Wang, Xiao-xiu; Li, Xin-wen

    2013-05-01

    The UOE process is widely recognized as an effective approach to manufacture large-diameter submerged-arc welding pipes. During the UOE process, the plate is crimped along its edge, pressed into U and O shape, welded closed and then expanded to obtain a circular pipe. In this study, the mechanical properties tests are carried out on the API X80 pipeline steel to establish the constitutive model. A two-dimensional finite element model of the UOE forming process is established under plane strain assumption. The deformed geometry of different forming steps and the distribution of equivalent plastic strain are obtained. The model is validated in practical manufacturing by comparing the forming quality, which shows a significant coherence in their geometric configurations. In particular, the effect of process parameters on the forming quality is analyzed. Those parameters are the yield strength of the plate, the location of C-die, the initial location of U-rollers, the displacement of U-rollers, the location of V-anvil, the final spacing between O-punch and O-die. The main forming quality includes the opening after O-forming, the ovality after pre-welding and expansion. The relation curves of parameters versus forming quality are obtained and illustrated.

  15. OPTIMIZATION OF A SOLAR SIMULATOR FOR PLANETARY-PHOTOCHEMICAL STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Es-sebbar, Et-touhami; Bénilan, Yves; Fray, Nicolas; Cottin, Hervé; Jolly, Antoine; Gazeau, Marie-Claire, E-mail: ettouhamiessbbar@gmail.com [Laboratoire Interuniversitaire des Systèmes Atmosphériques, LISA, UMR 7583, CNRS, Université Paris Est Créteil and Université Paris Diderot, Institute Pierre Simon Laplace, 61 Avenue du Général De Gaulle, F-94010 Créteil Cedex (France)

    2015-06-22

    Low-temperature microwave-powered plasma based on hydrogen and hydrogen with noble gas mixtures are widely used as a continuous vacuum ultraviolet (VUV) source in laboratory experiments carried out to mimic the photochemistry in astrophysical environments. In this work, we present a study dedicated to optimizing such sources in terms of mono-chromaticity at Lyα (H(Lyα) line at 121.6 nm ∼ 10.2 eV) and high spectral irradiance. We report the influence on the emission spectrum of a wide range of experimental conditions including gas composition (pure H{sub 2}, pure He, and H{sub 2}/He mixture), gas pressure, flow rates, and microwave power. The absolute spectral irradiance delivered by this VUV light source has been measured. With a microwave input power of 100 W, the best conditions for producing a quasi-monochromatic source are a 1% H{sub 2}/He gas mixture at a total pressure of 5 mbar and a flow rate of 2 sccm. By changing the microwave input power from 30 to 120 W, H(Lyα) increases by more than one order of magnitude. A comparison between the current measurements and the solar VUV spectral irradiance is reported over 115–170 nm.

  16. ATLAS Pixel-Optoboard Production and Simulation Studies

    CERN Document Server

    Nderitu, Simon

    At CERN, a Large collider will collide protons at high energies. There are four experiments being built to study the particle properties from the collision. The ATLAS experiment is the largest. It has many sub detectors among which is the Pixel detector which is the innermost part. The Pixel detector has eighty million channels that have to be read out. An optical link is utilized for the read out. It has optical to electronic interfaces both on the detector and off the detector at the counting room. The component on the detector in called the opto-board. This work discusses the production testing of the opto-boards to be installed on the detector. A total of 300 opto-boards including spares have been produced. The production was done in three laboratories among which is the laboratory at the University of Wuppertal which had the responsibility of Post production testing of all the one third of the total opto-boards. The results are discussed in this work. The analysis of the results from the total productio...

  17. Monte Carlo simulations for generic granite repository studies

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Shaoping [Los Alamos National Laboratory; Lee, Joon H [SNL; Wang, Yifeng [SNL

    2010-12-08

    In a collaborative study between Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) for the DOE-NE Office of Fuel Cycle Technologies Used Fuel Disposition (UFD) Campaign project, we have conducted preliminary system-level analyses to support the development of a long-term strategy for geologic disposal of high-level radioactive waste. A general modeling framework consisting of a near- and a far-field submodel for a granite GDSE was developed. A representative far-field transport model for a generic granite repository was merged with an integrated systems (GoldSim) near-field model. Integrated Monte Carlo model runs with the combined near- and farfield transport models were performed, and the parameter sensitivities were evaluated for the combined system. In addition, a sub-set of radionuclides that are potentially important to repository performance were identified and evaluated for a series of model runs. The analyses were conducted with different waste inventory scenarios. Analyses were also conducted for different repository radionuelide release scenarios. While the results to date are for a generic granite repository, the work establishes the method to be used in the future to provide guidance on the development of strategy for long-term disposal of high-level radioactive waste in a granite repository.

  18. Daily temperature integration: a simulation study to quantify energy consumption

    Energy Technology Data Exchange (ETDEWEB)

    Koerner, O. [The Royal Veterinary and Agricultural University, Taastrup (Denmark). Department of Agricultural Sciences, Section Horticulture; Bakker, M.J.; Heuvelink, E. [Wageningen University (Netherlands). Department of Plant Sciences, Horticultural Production Chains Group

    2004-03-01

    A combined greenhouse climate and control model was used to study energy consumption in year-round cut chrysanthemum. Temperature was either controlled for energy saving with temperature integration within 24 h using the margin between heating and ventilation temperature b as control (TI) or the temperature integration regime was restricted within 24 h by a set point for negative temperature difference between average day and average night temperature T{sub DIF} to attain a temperature regime for stem length control (TI{sub DIF}). Energy consumption was reduced by both regimes compared to a standard regime according to commercial practice when heating in winter was shifted to nighttime using a screen. With increasing weather fluctuations in spring and autumn, weekly energy consumption could decrease by more than 60% for TI with {+-}6{sup o}C temperature bandwidth. With TI{sub DIF} in the same period, only 37 or 17% (T{sub DIF} of -6 and -12{sup o}C, respectively) less energy was used than with a standard recommended climate regime (TP). In general, TI{sub DIF} reduced energy demand compared to TP, but energy saving was higher with TI. In deciding whether to apply either TI or TI{sub DIF}, the actual cultivation period is the most important criterion. Controlling stem length with a negative temperature difference in spring and autumn has the highest additional costs, control with almost no negative day to night temperature difference is possible in summer; during winter, both temperature control regimes result in an almost similar greenhouse climate. (author)

  19. Capacity improvement using simulation optimization approaches: A case study in the thermotechnology industry

    Science.gov (United States)

    Yelkenci Köse, Simge; Demir, Leyla; Tunalı, Semra; Türsel Eliiyi, Deniz

    2015-02-01

    In manufacturing systems, optimal buffer allocation has a considerable impact on capacity improvement. This study presents a simulation optimization procedure to solve the buffer allocation problem in a heat exchanger production plant so as to improve the capacity of the system. For optimization, three metaheuristic-based search algorithms, i.e. a binary-genetic algorithm (B-GA), a binary-simulated annealing algorithm (B-SA) and a binary-tabu search algorithm (B-TS), are proposed. These algorithms are integrated with the simulation model of the production line. The simulation model, which captures the stochastic and dynamic nature of the production line, is used as an evaluation function for the proposed metaheuristics. The experimental study with benchmark problem instances from the literature and the real-life problem show that the proposed B-TS algorithm outperforms B-GA and B-SA in terms of solution quality.

  20. A new solver for granular avalanche simulation: Indoor experiment verification and field scale case study

    Science.gov (United States)

    Wang, XiaoLiang; Li, JiaChun

    2017-12-01

    A new solver based on the high-resolution scheme with novel treatments of source terms and interface capture for the Savage-Hutter model is developed to simulate granular avalanche flows. The capability to simulate flow spread and deposit processes is verified through indoor experiments of a two-dimensional granular avalanche. Parameter studies show that reduction in bed friction enhances runout efficiency, and that lower earth pressure restraints enlarge the deposit spread. The April 9, 2000, Yigong avalanche in Tibet, China, is simulated as a case study by this new solver. The predicted results, including evolution process, deposit spread, and hazard impacts, generally agree with site observations. It is concluded that the new solver for the Savage-Hutter equation provides a comprehensive software platform for granular avalanche simulation at both experimental and field scales. In particular, the solver can be a valuable tool for providing necessary information for hazard forecasts, disaster mitigation, and countermeasure decisions in mountainous areas.

  1. PEPT: An invaluable tool for 3-D particle tracking and CFD simulation verification in hydrocyclone studies

    Directory of Open Access Journals (Sweden)

    Hoffmann Alex C.

    2013-05-01

    Full Text Available Particle tracks in a hydrocyclone generated both experimentally by positron emission particle tracking (PEPT and numerically with Eulerian-Lagranian CFD have been studied and compared. A hydrocyclone with a cylinder-on-cone design was used in this study, the geometries used in the CFD simulations and in the experiments being identical. It is shown that it is possible to track a fast-moving particle in a hydrocyclone using PEPT with high temporal and spatial resolutions. The numerical 3-D particle trajectories were generated using the Large Eddy Simulation (LES turbulence model for the fluid and Lagrangian particle tracking for the particles. The behaviors of the particles were analyzed in detail and were found to be consistent between experiments and CFD simulations. The tracks of the particles are discussed and related to the fluid flow field visualized in the CFD simulations using the cross-sectional static pressure distribution.

  2. FLUKA simulation studies on in-phantom dosimetric parameters of a LINAC-based BNCT

    Science.gov (United States)

    Ghal-Eh, N.; Goudarzi, H.; Rahmani, F.

    2017-12-01

    The Monte Carlo simulation code, FLUKA version 2011.2c.5, has been used to estimate the in-phantom dosimetric parameters for use in BNCT studies. The in-phantom parameters of a typical Snyder head, which are necessary information prior to any clinical treatment, have been calculated with both FLUKA and MCNPX codes, which exhibit a promising agreement. The results confirm that FLUKA can be regarded as a good alternative for the MCNPX in BNCT dosimetry simulations.

  3. Round Robin Study: Molecular Simulation of Thermodynamic Properties from Models with Internal Degrees of Freedom.

    Science.gov (United States)

    Schappals, Michael; Mecklenfeld, Andreas; Kröger, Leif; Botan, Vitalie; Köster, Andreas; Stephan, Simon; García, Edder J; Rutkai, Gabor; Raabe, Gabriele; Klein, Peter; Leonhard, Kai; Glass, Colin W; Lenhard, Johannes; Vrabec, Jadran; Hasse, Hans

    2017-09-12

    Thermodynamic properties are often modeled by classical force fields which describe the interactions on the atomistic scale. Molecular simulations are used for retrieving thermodynamic data from such models, and many simulation techniques and computer codes are available for that purpose. In the present round robin study, the following fundamental question is addressed: Will different user groups working with different simulation codes obtain coinciding results within the statistical uncertainty of their data? A set of 24 simple simulation tasks is defined and solved by five user groups working with eight molecular simulation codes: DL_POLY, GROMACS, IMC, LAMMPS, ms2, NAMD, Tinker, and TOWHEE. Each task consists of the definition of (1) a pure fluid that is described by a force field and (2) the conditions under which that property is to be determined. The fluids are four simple alkanes: ethane, propane, n-butane, and iso-butane. All force fields consider internal degrees of freedom: OPLS, TraPPE, and a modified OPLS version with bond stretching vibrations. Density and potential energy are determined as a function of temperature and pressure on a grid which is specified such that all states are liquid. The user groups worked independently and reported their results to a central instance. The full set of results was disclosed to all user groups only at the end of the study. During the study, the central instance gave only qualitative feedback. The results reveal the challenges of carrying out molecular simulations. Several iterations were needed to eliminate gross errors. For most simulation tasks, the remaining deviations between the results of the different groups are acceptable from a practical standpoint, but they are often outside of the statistical errors of the individual simulation data. However, there are also cases where the deviations are unacceptable. This study highlights similarities between computer experiments and laboratory experiments, which are

  4. Study of Structural Properties in Complex Fluids by Addition of Surfactants Using DPD Simulation

    CERN Document Server

    Mayoral, Estela; Martínez-Magadán, José Manuel; Ortega, Alejandro; Soto, Ismael

    2014-01-01

    In this work we study the tertiary structure of ionic surfactants when the pH in the system is modified using electrostatic dissipative particle dynamics simulations (DPD). The dependence with pH and kind of surfactant is presented. Our simulations reproduce the experimental behavior reported in the literature. The scaling for the radius of gyration with the size of the molecule as a function of pH is also obtained.

  5. Pharmacists’ response to anaphylaxis in the community (PRAC): a randomised, simulated patient study of pharmacist practice

    OpenAIRE

    Salter, Sandra M; Delfante, Brock; de Klerk, Sarah; Sanfilippo, Frank M.; Clifford, Rhonda M.

    2014-01-01

    Objective To evaluate how community pharmacists manage patients with anaphylaxis. Design A randomised, cross-sectional, simulated patient study of community pharmacist practice. Setting 300 metropolitan pharmacies located in Perth Australia, randomised to three groups of 100 pharmacies. Each group corresponded to a different epinephrine autoinjector: original EpiPen, new-look EpiPen or Anapen. Participants 300 pharmacies were visited with 271 simulated patient visits included in the final ana...

  6. Implementing a Workplace Violence Simulation for Undergraduate Nursing Students: A Pilot Study.

    Science.gov (United States)

    Martinez, Angel Johann Solorzano

    2017-10-01

    Workplace violence (WPV) is an undesired phenomenon affecting nurses and nursing students. Nursing simulations allow students to learn and practice skills in a controlled setting. The development of the pilot study, "Mental Health Nursing Simulation on Workplace Violence," is presented. A simulated scenario using a standardized patient (SP) behaving as an agitated psychiatric patient was developed for undergraduate nursing students enrolled in a psychiatric nursing course. The simulation aimed to enhance students' knowledge about WPV, increase their confidence and ability to recognize signs of aggression, practice evidence-based interventions to de-escalate agitated patients, and evaluate the simulation. Surveys and the Mental Health Nursing Clinical Confidence Scale were used to measure the aims yielding qualitative and quantitative data. An increase in students' confidence and knowledge was obtained post-simulation. Students rated the simulation as useful. The use of a SP created an experiential learning environment for participants. [Journal of Psychosocial Nursing and Mental Health Services, 55(10), 39-44.]. Copyright 2017, SLACK Incorporated.

  7. Individualized feedback during simulated laparoscopic training:a mixed methods study.

    Science.gov (United States)

    Ahlborg, Liv; Weurlander, Maria; Hedman, Leif; Nisel, Henry; Lindqvist, Pelle G; Felländer-Tsai, Li; Enochsson, Lars

    2015-07-29

    This study aimed to explore the value of individualized feedback on performance, flow and self-efficacy during simulated laparoscopy. Furthermore, we wished to explore attitudes towards feedback and simulator training among medical students. Sixteen medical students were included in the study and randomized to laparoscopic simulator training with or without feedback. A teacher provided individualized feedback continuously throughout the procedures to the target group. Validated questionnaires and scales were used to evaluate self-efficacy and flow. The Mann-Whitney U test was used to evaluate differences between groups regarding laparoscopic performance (instrument path length), self-efficacy and flow. Qualitative data was collected by group interviews and interpreted using inductive thematic analyses. Sixteen students completed the simulator training and questionnaires. Instrument path length was shorter in the feedback group (median 3.9 m; IQR: 3.3-4.9) as compared to the control group (median 5.9 m; IQR: 5.0-8.1), pfeedback group were more concentrated on the task and also more anxious. Both groups had high ambitions to succeed and also expressed the importance of getting feedback. The authenticity of the training scenario was important for the learning process. This study highlights the importance of individualized feedback during simulated laparoscopy training. The next step is to further optimize feedback and to transfer standardized and individualized feedback from the simulated setting to the operating room.

  8. Simulation Study of a Thermionic RF Gun for High Brightness and Short Pulse Beam

    CERN Document Server

    Tanaka, Takumi; Hinode, Fujio; Kawai, Masayuki; Miyamoto, Atsushi; Shinto, Katsuhiro

    2005-01-01

    Characteristics of thermionic RF guns are not understood completely. In particular, measured intense beam emittances extracted from thermionic RF guns do not agree well with simulated values so far. Most of simulation codes solve the equation of electron motion in an intrinsic mode of the RF field calculated by a separated code. The way of such simulation codes is not self-consistent completely. That is probably a major reason for the discrepancy between the experiments and the simulations. One of the other way for a self-consistent simulation codes is to use an FDTD (Finite Difference Time Domain) method. Since the FDTD method can take into account the microwave propagation including the space charge effect and the beam loading self-consistently, we have developed an FDTD code as 3-D Maxwell's equation solver and applied for a study of beam dynamics in a thermionic RF gun. The main purpose of simulaiton study is to obtain overall properties of the beam dynamics at the time. The goal of this simulation study ...

  9. Simulation of fruit pallet movement in the port of Durban: A case study

    African Journals Online (AJOL)

    This paper gives an overview of a discrete-event simulation study that was performed on pallet movement at Fresh Produce Terminals in the port of Durban, South Africa. The study formed part of an extended study of the logistics infrastructure of the South African fresh fruit industry and its export supply chain. The focus in ...

  10. The Use of Instructional Simulations to Support Classroom Teaching: A Crisis Communication Case Study

    Science.gov (United States)

    Shifflet, Mark; Brown, Jane

    2006-01-01

    The purpose of this study was to investigate how exposure to classroom instruction affected the use of a computer simulation that was designed to provide students an opportunity to apply material presented in class. The study involved an analysis of a computer-based crisis communication case study designed for a college-level public relations…

  11. Tomographic image of prompt gamma ray from boron neutron capture therapy: A Monte Carlo simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Dokun; Suh, Tae Suk [Catholic Univ. of Korea, Seoul (Korea, Republic of); Hong, Key Jo [Stanford Univ., Stanford (United States)

    2014-05-15

    The resulting neutron captures in {sup 10}B are used for radiation therapy. The occurrence point of the characteristic 478 keV prompt gamma rays agrees with the neutron capture point. If these prompt gamma rays are detected by external instruments such as a gamma camera or single photon emission computed tomography (SPECT), the therapy region can be monitored during the treatment using images. A feasibility study and analysis of a reconstructed image using many projections (128) were conducted. The optimization of the detection system and a detailed neutron generator simulation were beyond the scope of this study. The possibility of extracting a 3D BNCT-SPECT image was confirmed using the Monte Carlo simulation and OSEM algorithm. The quality of the prompt gamma ray SPECT image obtained from BNCT was evaluated quantitatively using three different boron uptake regions and was shown to depend on the location and size relations. The prospects for obtaining an actual BNCT-SPECT image were also estimated from the quality of the simulated image and the simulation conditions. When multi tumor regions should be treated using the BNCT method, a reasonable model to determine how many useful images can be obtained from SPECT can be provided to the BNCT facilities based on the preceding imaging research. However, because the scope of this research was limited to checking the feasibility of 3D BNCT-SPECT image reconstruction using multiple projections, along with an evaluation of the image, some simulation conditions were taken from previous studies. In the future, a simulation will be conducted that includes optimized conditions for an actual BNCT facility, along with an imaging process for motion correction in BNCT. Although an excessively long simulation time was required to obtain enough events for image reconstruction, the feasibility of acquiring a 3D BNCT-SPECT image using multiple projections was confirmed using a Monte Carlo simulation, and a quantitative image

  12. A study of the use of simulated work task situations in interactive information retrieval evaluations

    DEFF Research Database (Denmark)

    Borlund, Pia

    2016-01-01

    Purpose – The purpose of this paper is to report a study of how the test instrument of a simulated work task situation is used in empirical evaluations of interactive information retrieval (IIR) and reported in the research literature. In particular, the author is interested to learn whether...... partly via citation analysis by use of Web of Science®, and partly by systematic search of online repositories. On this basis, 67 individual publications were identified and they constitute the sample of analysis. Findings – The analysis reveals a need for clarifications of how to use simulated work task...... situations in IIR evaluations. In particular, with respect to the design and creation of realistic simulated work task situations. There is a lack of tailoring of the simulated work task situations to the test participants. Likewise, the requirement to include the test participants’ personal information...

  13. MixSim : An R Package for Simulating Data to Study Performance of Clustering Algorithms

    Directory of Open Access Journals (Sweden)

    Volodymyr Melnykov

    2012-11-01

    Full Text Available The R package MixSim is a new tool that allows simulating mixtures of Gaussian distributions with different levels of overlap between mixture components. Pairwise overlap, defined as a sum of two misclassification probabilities, measures the degree of interaction between components and can be readily employed to control the clustering complexity of datasets simulated from mixtures. These datasets can then be used for systematic performance investigation of clustering and finite mixture modeling algorithms. Among other capabilities of MixSim, there are computing the exact overlap for Gaussian mixtures, simulating Gaussian and non-Gaussian data, simulating outliers and noise variables, calculating various measures of agreement between two partitionings, and constructing parallel distribution plots for the graphical display of finite mixture models. All features of the package are illustrated in great detail. The utility of the package is highlighted through a small comparison study of several popular clustering algorithms.

  14. A study on T-shape Compton suppression spectrometer by Monte Carlo simulation

    Science.gov (United States)

    Kiang, L. L.; Tsou, R. H.; Lin, W. J.; Lin, Simon C.; Kiang, G. C.; Teng, P. K.; Li, S. D.

    1993-04-01

    The geometrical parameters which affect the suppression factor for a T-shape HPGe-NaI(Tl) Compton suppression spectrometer are studied by a Monte Carlo simulation method. We simulate two combinations of this sort of Compton suppression spectrometer (113 and 146 cm 3 high-purity germanium detector is inserted into 22.9 cm Ø × 25.4 and 14.0 cm Ø × 17.8 cm annular NaI(Tl) shield detector, respectively). The simulation results of suppression factor are consistent with the results from the experiment. The optimal position of the HPGe detector within the shield is about at the half length of the radius of the NaI(Tl) detector for Compton suppression. Further simulation finds that the suppression factor is independent of the length of the shield but dependent on its radius. Other geometrical topologies for the shield are also discussed.

  15. Simulated Waste for Leaching and Filtration Studies--Laboratory Preparation Procedure

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Harry D.; Russell, Renee L.; Peterson, Reid A.

    2009-10-27

    This report discusses the simulant preparation procedure for producing multi-component simulants for leaching and filtration studies, including development and comparison activities in accordance with the test plan( ) prepared and approved in response to the Test Specification 24590-WTP-TSP-RT-06-006, Rev 0 (Smith 2006). A fundamental premise is that this approach would allow blending of the different components to simulate a wide variety of feeds to be treated in the Hanford Tank Waste Treatment and Immobilization Plant (WTP). For example, a given feed from the planned feed vector could be selected, and the appropriate components would then be blended to achieve a representation of that particular feed. Using the blending of component simulants allows the representation of a much broader spectrum of potential feeds to the Pretreatment Engineering Platform (PEP).

  16. A simulation study on the focal plane detector of the LAUE project

    Science.gov (United States)

    Khalil, M.; Frontera, F.; Caroli, E.; Virgilli, E.; Valsan, V.

    2015-06-01

    The LAUE project, supported by the Italian Space Agency (ASI), is devoted to the development of a long focal length (even 20 m or longer) Laue lens for gamma ray astronomy between 80 and 600 keV. These lenses take advantage of Bragg diffraction to focus radiation onto a small spot drastically improving the signal to noise ratio as well as reducing the required size of the detector significantly. In this paper we present a Monte-Carlo simulation study with MEGALIB to optimize, for space applications, the detector size to achieve high detection efficiency, and to optimize the position resolution of the detector to reconstruct the Point Spread Function of the lens considered for the LAUE project. Then we will show simulations, using the SILVACO semiconductor simulation toolkit, on the optimized detector to estimate its capacitance per channel and depletion voltage. In all of the simulations, two materials were compared; a low density material (Silicon) and a high density material (Germanium).

  17. NV Energy Large-Scale Photovoltaic Integration Study: Intra-Hour Dispatch and AGC Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Shuai; Etingov, Pavel V.; Meng, Da; Guo, Xinxin; Jin, Chunlian; Samaan, Nader A.

    2013-01-02

    The uncertainty and variability with photovoltaic (PV) generation make it very challenging to balance power system generation and load, especially under high penetration cases. Higher reserve requirements and more cycling of conventional generators are generally anticipated for large-scale PV integration. However, whether the existing generation fleet is flexible enough to handle the variations and how well the system can maintain its control performance are difficult to predict. The goal of this project is to develop a software program that can perform intra-hour dispatch and automatic generation control (AGC) simulation, by which the balancing operations of a system can be simulated to answer the questions posed above. The simulator, named Electric System Intra-Hour Operation Simulator (ESIOS), uses the NV Energy southern system as a study case, and models the system’s generator configurations, AGC functions, and operator actions to balance system generation and load. Actual dispatch of AGC generators and control performance under various PV penetration levels can be predicted by running ESIOS. With data about the load, generation, and generator characteristics, ESIOS can perform similar simulations and assess variable generation integration impacts for other systems as well. This report describes the design of the simulator and presents the study results showing the PV impacts on NV Energy real-time operations.

  18. Organizational culture shapes the adoption and incorporation of simulation into nursing curricula: a grounded theory study.

    Science.gov (United States)

    Taplay, Karyn; Jack, Susan M; Baxter, Pamela; Eva, Kevin; Martin, Lynn

    2014-01-01

    Purpose. To create a substantive mid-range theory explaining how the organizational cultures of undergraduate nursing programs shape the adoption and incorporation of mid-to high-level technical fidelity simulators as a teaching strategy within curricula. Method. A constructivist grounded theory was used to guide this study which was conducted in Ontario, Canada, during 2011-12. Semistructured interviews (n = 43) with participants that included nursing administrators, nursing faculty, and simulation leaders across multiple programs (n = 13) informed this study. Additionally, key documents (n = 67) were reviewed. Purposeful and theoretical sampling was used and data were collected and analyzed simultaneously. Data were compared among and between sites. Findings. The organizational elements that shape simulation in nursing (OESSN) model depicts five key organizational factors at the nursing program level that shaped the adoption and incorporation of simulation: (1) leaders working in tandem, (2) information exchange, (3) physical locale, (4) shared motivators, and (5) scaffolding to manage change. Conclusions. The OESSN model provides an explanation of the organizational factors that contributed to the adoption and incorporation of simulation into nursing curricula. Nursing programs that use the OESSN model may experience a more rapid or broad uptake of simulation when organizational factors that impact adoption and incorporation are considered and planned for.

  19. Heart rate, anxiety and performance of residents during a simulated critical clinical encounter: a pilot study.

    Science.gov (United States)

    Clarke, Samuel; Horeczko, Timothy; Cotton, Dale; Bair, Aaron

    2014-07-27

    High-fidelity patient simulation has been praised for its ability to recreate lifelike training conditions. The degree to which high fidelity simulation elicits acute emotional and physiologic stress among participants - and the influence of acute stress on clinical performance in the simulation setting - remain areas of active exploration. We examined the relationship between residents' self-reported anxiety and a proxy of physiologic stress (heart rate) as well as their clinical performance in a simulation exam using a validated assessment of non-technical skills, the Ottawa Crisis Resource Management Global Rating Scale (Ottawa GRS). This was a prospective observational cohort study of emergency medicine residents at a single academic center. Participants managed a simulated clinical encounter. Anxiety was assessed using a pre- and post-simulation survey, and continuous cardiac monitoring was performed on each participant during the scenario. Performance in the simulation scenario was graded by faculty raters using a critical actions checklist and the Ottawa GRS instrument. Data collection occurred during the 2011 academic year. Of 40 eligible residents, 34 were included in the analysis. The median baseline heart rate for participants was 70 beats per minute (IQR: 62 - 78). During the simulation, the median maximum heart rate was 140 beats per minute (IQR: 137 - 151). The median minimum heart rate during simulation was 81 beats per minute (IQR: 72 - 92), and mean heart rate was 117 beats per minute (95% CI: 111 - 123). Pre- and post-simulation anxiety scores were equal (mean 3.3, IQR: 3 to 4). The minimum and maximum Overall Ottawa GRS scores were 2.33 and 6.67, respectively. The median Overall score was 5.63 (IQR: 5.0 to 6.0). Of the candidate predictors of Overall performance in a multivariate logistic regression model, only PGY status showed statistical significance (P = 0.02). Simulation is associated with physiologic stress, and heart rate elevation alone

  20. Simulation studies for a high resolution time projection chamber at the international linear collider

    Energy Technology Data Exchange (ETDEWEB)

    Muennich, A.

    2007-03-26

    The International Linear Collider (ILC) is planned to be the next large accelerator. The ILC will be able to perform high precision measurements only possible at the clean environment of electron positron collisions. In order to reach this high accuracy, the requirements for the detector performance are challenging. Several detector concepts are currently under study. The understanding of the detector and its performance will be crucial to extract the desired physics results from the data. To optimise the detector design, simulation studies are needed. Simulation packages like GEANT4 allow to model the detector geometry and simulate the energy deposit in the different materials. However, the detector response taking into account the transportation of the produced charge to the readout devices and the effects ofthe readout electronics cannot be described in detail. These processes in the detector will change the measured position of the energy deposit relative to the point of origin. The determination of this detector response is the task of detailed simulation studies, which have to be carried out for each subdetector. A high resolution Time Projection Chamber (TPC) with gas amplification based on micro pattern gas detectors, is one of the options for the main tracking system at the ILC. In the present thesis a detailed simulation tool to study the performance of a TPC was developed. Its goal is to find the optimal settings to reach an excellent momentum and spatial resolution. After an introduction to the present status of particle physics and the ILC project with special focus on the TPC as central tracker, the simulation framework is presented. The basic simulation methods and implemented processes are introduced. Within this stand-alone simulation framework each electron produced by primary ionisation is transferred through the gas volume and amplified using Gas Electron Multipliers (GEMs). The output format of the simulation is identical to the raw data from a

  1. A simulator study of the combined effects of alcohol and marihuana on driving behavior--phase II

    Science.gov (United States)

    1983-02-01

    Author's abstract: The study described in this report investigated the effects of alcohol and marihuana, alone and in combination, on driver performance and behavior in a fully interactive driving simulator. The simulator provided the driver a comple...

  2. Impact of prebriefing on competency performance, clinical judgment and experience in simulation: An experimental study.

    Science.gov (United States)

    Page-Cutrara, Karin; Turk, Melanie

    2017-01-01

    Prebriefing is the introductory phase of the simulation process, however, little nursing education research is available on this aspect of simulation. Reflection theory and concept mapping informed a model-based structured prebriefing activity to prepare students for meaningful simulation learning. The aim of this study was to examine the intervention of structured prebriefing for its effect on nursing students' competency performance, clinical judgment and their perceived prebriefing experience. An experimental group-randomized design was used in this study; the intervention group who received structured prebriefing was compared to the control group. The study was conducted at a university school of nursing in Canada. Baccalaureate nursing students (N=76) enrolled in a fourth-year medical-surgical course participated in this study. Competency performance, clinical judgment, and the perception of the prebriefing experience of those participants receiving structured prebriefing and those receiving traditional prebriefing activities, were compared. The relationship between simulation performance and students' self-rated prebriefing experience was also examined. Scores from the Creighton Competency Evaluation Instrument and the Prebriefing Experience Scale were analyzed using parametric and non-parametric statistics. A statistically significant difference was demonstrated between groups for competency performance (pperformance. Theory-based, structured prebriefing can impact nursing student competency performance, clinical judgment and perceptions of prebriefing, and may enhance meaningful simulation learning. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Studying distributed cognition of simulation-based team training with DiCoT.

    Science.gov (United States)

    Rybing, Jonas; Nilsson, Heléne; Jonson, Carl-Oscar; Bang, Magnus

    2016-03-01

    Health care organizations employ simulation-based team training (SBTT) to improve skill, communication and coordination in a broad range of critical care contexts. Quantitative approaches, such as team performance measurements, are predominantly used to measure SBTTs effectiveness. However, a practical evaluation method that examines how this approach supports cognition and teamwork is missing. We have applied Distributed Cognition for Teamwork (DiCoT), a method for analysing cognition and collaboration aspects of work settings, with the purpose of assessing the methodology's usefulness for evaluating SBTTs. In a case study, we observed and analysed four Emergo Train System® simulation exercises where medical professionals trained emergency response routines. The study suggests that DiCoT is an applicable and learnable tool for determining key distributed cognition attributes of SBTTs that are of importance for the simulation validity of training environments. Moreover, we discuss and exemplify how DiCoT supports design of SBTTs with a focus on transfer and validity characteristics. Practitioner Summary: In this study, we have evaluated a method to assess simulation-based team training environments from a cognitive ergonomics perspective. Using a case study, we analysed Distributed Cognition for Teamwork (DiCoT) by applying it to the Emergo Train System®. We conclude that DiCoT is useful for SBTT evaluation and simulator (re)design.

  4. A prospective study of lip adaptation during six months of simulated mandibular dental arch expansion.

    Science.gov (United States)

    Shellhart, W C; Moawad, M I; Matheny, J; Paterson, R L; Hicks, E P

    1997-01-01

    The stability of dental arch expansion with conventional orthodontic treatments is disappointing. An increase in labial soft tissue pressure resulting from the expansion may contribute to this instability. An 8-month study of lip pressure changes resulting from lip bumper wear has been conducted, but no long-term studies have been conducted on pressure changes resulting from conventional expansion using fixed appliances. The purpose of the current study was to investigate changes in labial soft tissue pressures when conventional expansion was simulated. Twenty-two subjects wore a stent simulating mandibular dental arch expansion. They were instructed to wear the stent full-time. Lip pressure was recorded initially at 1 week, and monthly for 6 months. A repeated measures ANOVA was used for statistical analysis. A statistically significant (P < or = 0.05) increase in pressure was documented after initial insertion of the expansion-simulating stent. The increase was not maintained, suggesting an adaptation of the labial soft tissues.

  5. Heat and mass transfer in wooden dowels during a simulated fire: an experimental and analytical study

    Science.gov (United States)

    J. A. Mardini; A. S. Lavine; V. K.. Dhir

    1996-01-01

    Abstract--An experimental and analytical study of heat and mass transfer in wooden dowels during a simulated fire is presented in this paper. The goal of this study is to understand the processes of heat and mass transfer in wood during wildland fires. A mathematical model is developed to describe the processes of heating, drying and pyrolysis of wood until ignition...

  6. Energy saving prospectives of combined heat and power in horticulture in the Netherlands: a simulation study

    NARCIS (Netherlands)

    Zwart, de H.F.; Bot, G.P.A.

    1997-01-01

    This paper studies the prospects for the use of reject heat from on-site combined heat and power generation in horticulture. In particular, the consequences of CO2-dosing with exhaust gases is studied. All computations are made with a recently developed dynamic simulation model describing the energy

  7. Magnetic force microscopy and simulation studies on Co50Fe50 ...

    Indian Academy of Sciences (India)

    We studied the magnetization reversal mechanism of single-layered Co50Fe50 nanomagnets by measuring the magnetization reversal and using the micromagnetic simulations. The magnetization reversal strongly depends on the thickness of the nanomagnets. In the remanent state, the magnetic force microscopy studies ...

  8. Simulation studies on the effect of a buffer layer on the external ...

    Indian Academy of Sciences (India)

    Wintec

    Simulation studies on the effect of a buffer layer on the external parameters of hydrogenated amorphous silicon p–i–n ... studied material because of its tremendous potential in the fabrication of low cost solar cells for .... Miro Zeman 1999 Amorphous semiconductor analysis users manual, Version 3.0, TU Delft. Petit A M H N ...

  9. Study of Monte Carlo Simulation Method for Methane Phase Diagram Prediction using Two Different Potential Models

    KAUST Repository

    Kadoura, Ahmad

    2011-06-06

    Lennard‐Jones (L‐J) and Buckingham exponential‐6 (exp‐6) potential models were used to produce isotherms for methane at temperatures below and above critical one. Molecular simulation approach, particularly Monte Carlo simulations, were employed to create these isotherms working with both canonical and Gibbs ensembles. Experiments in canonical ensemble with each model were conducted to estimate pressures at a range of temperatures above methane critical temperature. Results were collected and compared to experimental data existing in literature; both models showed an elegant agreement with the experimental data. In parallel, experiments below critical temperature were run in Gibbs ensemble using L‐J model only. Upon comparing results with experimental ones, a good fit was obtained with small deviations. The work was further developed by adding some statistical studies in order to achieve better understanding and interpretation to the estimated quantities by the simulation. Methane phase diagrams were successfully reproduced by an efficient molecular simulation technique with different potential models. This relatively simple demonstration shows how powerful molecular simulation methods could be, hence further applications on more complicated systems are considered. Prediction of phase behavior of elemental sulfur in sour natural gases has been an interesting and challenging field in oil and gas industry. Determination of elemental sulfur solubility conditions helps avoiding all kinds of problems caused by its dissolution in gas production and transportation processes. For this purpose, further enhancement to the methods used is to be considered in order to successfully simulate elemental sulfur phase behavior in sour natural gases mixtures.

  10. Comparative study of baccalaureate nursing student self-efficacy before and after simulation.

    Science.gov (United States)

    Cardoza, Maureen P; Hood, Patrice A

    2012-03-01

    Evaluation of learning and the development of prelicensure nursing education include an exploration of new teaching models and techniques for student learning assessment. The utilization of high-fidelity human simulation in nursing provides nursing faculty and students the opportunity to expand the boundaries of conventional learning from an instructional paradigm to a blending of modalities that enrich the student experience and provide an avenue for self-determined learning. The inception of computer-generated high-fidelity human simulation technology into the undergraduate nursing curriculum generated this correlation study, which examined two separate groups of senior baccalaureate nursing students' reported self-efficacy for providing family-centered care. This research examined each group of students' reported self-efficacy on the first day of the pediatric semester before and after simulation and on the last day of the pediatric semester before and after simulation. In addition, the relationship between two senior baccalaureate nursing student groups' reported self-efficacy at four data points was examined. The concluding data identified that senior baccalaureate nursing students have unrealistic self-assessments of their clinical knowledge and nursing performance capabilities before simulation scenario participation. The perceived ability of undergraduate students to self-identify their previously acquired knowledge and transferable clinical reasoning to family-centered situations is inaccurate. Human simulators are an effective teaching and learning modality in measuring factors that affect student outcomes.

  11. A computer simulation study of VNTR population genetics: Constrained recombination rules out the infinite alleles model

    Energy Technology Data Exchange (ETDEWEB)

    Harding, R.M.; Martinson, J.J.; Flint, J.; Clegg, J.B.; Boyce, A.J. (Univ. of Oxford (United Kingdom))

    1993-11-01

    Extensive allelic diversity in variable numbers of tandem repeats (VNTRs) has been discovered in the human genome. For population genetic studies of VNTRs, such as forensic applications, it is important to know whether a neutral mutation-drift balance of VNTR polymorphism can be represented by the infinite alleles model. The assumption of the infinite alleles model that each new mutant is unique is very likely to be violated by unequal sister chromatid exchange (USCE), the primary process believed to generate VNTR mutants. The authors show that increasing both mutation rates and misalignment constraint for intrachromosomal recombination in a computer simulation model reduces simulated VNTR diversity below the expectations of the infinite alleles model. Maximal constraint, represented as slippage of single repeats, reduces simulated VNTR diversity to levels expected from the stepwise mutation model. Although misalignment rule is the more important variable, mutation rate also has an effect. At moderate rates of USCE, simulated VNTR diversity fluctuates around infinite alleles expectation. However, if rates of USCE are high, as for hypervariable VNTRs, simulated VNTR diversity is consistently lower than predicted by the infinite alleles model. This has been observed for many VNTRs and accounted for by technical problems in distinguishing alleles of neighboring size classes. The authors use sampling theory to confirm the intrinsically poor fit to the infinite model of both simulated VNTR diversity and observed VNTR polymorphisms sampled from two Papua New Guinean populations. 25 refs., 20 figs., 4 tabs.

  12. Simulation debriefing based on principles of transfer of learning: A pilot study.

    Science.gov (United States)

    Johnston, Sandra; Coyer, Fiona; Nash, Robyn

    2017-09-01

    Upon completion of undergraduate nursing courses, new graduates are expected to transition seamlessly into practice. Education providers face challenges in the preparation of undergraduate nurses due to increasing student numbers and decreasing availability of clinical placement sites. High fidelity patient simulation is an integral component of nursing curricula as an adjunct to preparation for clinical placement. Debriefing after simulation is an area where the underlying structure of problems can consciously be explored. When central principles of problems are identified, they can then be used in situations that differ from the simulation experience. Third year undergraduate nursing students participated in a pilot study conducted to test a debriefing intervention where the intervention group (n=7) participated in a simulation, followed by a debriefing based on transfer of learning principles. The control group (n=5) participated in a simulation of the same scenario, followed by a standard debriefing. Students then attended focus group interviews. The results of this pilot test provided preliminary information that the debriefing approach based on transfer of learning principles may be a useful way for student nurses to learn from a simulated experience and consider the application of learning to future clinical encounters. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. A Study of the Electrostatic Interaction Between Insulators and Martian/Lunar Soil Simulants

    Science.gov (United States)

    Mantovani, James G.

    2001-01-01

    Using our previous experience with the Mars Environmental Compatibility Assessment (MECA) electrometer, we have designed a new type of aerodynamic electrometer. The goal of the research was to measure the buildup of electrostatic surface charge on a stationary cylindrical insulator after windborne granular particles have collided with the insulator surface in a simulated dust storm. The experiments are performed inside a vacuum chamber. This allows the atmospheric composition and pressure to be controlled in order to simulate the atmospheric conditions near the equator on the Martian surface. An impeller fan was used to propel the dust particles at a cylindrically shaped insulator under low vacuum conditions. We tested the new electrometer in a 10 mbar CO2 atmosphere by exposing two types of cylindrical insulators, Teflon (1.9 cm diameter) and Fiberglass (2.5 cm diameter), to a variety of windborne granular particulate materials. The granular materials tested were JSC Mars-1 simulant, which is a mixture of coarse and fine (insulator capped planar electrode for measuring the amount of electrostatic charge produced by rubbing an insulator surface over Martian and lunar soil simulants. The results of this study indicate that it is possible to detect triboelectric charging of insulator surfaces by windborne Martian soil simulant, and by individual mineral constituents of the soil simulant. We have also found that Teflon and Fiberglass insulator surfaces respond in different ways by developing opposite polarity surface charge, which decays at different rates after the particle impacts cease.

  14. Agent Behavior-Based Simulation Study on Mass Collaborative Product Development Process

    Directory of Open Access Journals (Sweden)

    Shuo Zhang

    2015-01-01

    Full Text Available Mass collaborative product development (MCPD benefits people by high innovation products with lower cost and shorter lead time due to quick development of group innovation, Internet-based customization, and prototype manufacturing. Simulation is an effective way to study the evolution process and therefore to guarantee the success of MCPD. In this paper, an agent behavior-based simulation approach of MCPD is developed, which models the MCPD process as the interactive process of design agents and the environment objects based on Complex Adaptive System (CAS theory. Next, the structure model of design agent is proposed, and the modification and collaboration behaviors are described. Third, the agent behavior-based simulation flow of MCPD is designed. At last, simulation experiments are carried out based on an engineering case of mobile phone design. The experiment results show the following: (1 the community scale has significant influence on MCPD process; (2 the simulation process can explicitly represent the modification and collaboration behaviors of design agents; (3 the community evolution process can be observed and analyzed dynamically based on simulation data.

  15. Simulation-Based Approach for Studying the Balancing of Local Smart Grids with Electric Vehicle Batteries

    Directory of Open Access Journals (Sweden)

    Juhani Latvakoski

    2015-07-01

    Full Text Available Modern society is facing great challenges due to pollution and increased carbon dioxide (CO2 emissions. As part of solving these challenges, the use of renewable energy sources and electric vehicles (EVs is rapidly increasing. However, increased dynamics have triggered problems in balancing energy supply and consumption demand in the power systems. The resulting uncertainty and unpredictability of energy production, consumption, and management of peak loads has caused an increase in costs for energy market actors. Therefore, the means for studying the balancing of local smart grids with EVs is a starting point for this paper. The main contribution is a simulation-based approach which was developed to enable the study of the balancing of local distribution grids with EV batteries in a cost-efficient manner. The simulation-based approach is applied to enable the execution of a distributed system with the simulation of a local distribution grid, including a number of charging stations and EVs. A simulation system has been constructed to support the simulation-based approach. The evaluation has been carried out by executing the scenario related to balancing local distribution grids with EV batteries in a step-by-step manner. The evaluation results indicate that the simulation-based approach is able to facilitate the evaluation of smart grid– and EV-related communication protocols, control algorithms for charging, and functionalities of local distribution grids as part of a complex, critical cyber-physical system. In addition, the simulation system is able to incorporate advanced methods for monitoring, controlling, tracking, and modeling behavior. The simulation model of the local distribution grid can be executed with the smart control of charging and discharging powers of the EVs according to the load situation in the local distribution grid. The resulting simulation system can be applied to the study of balancing local smart grids with EV

  16. Application of process simulators in chemical engineering process design -natural gas separation plant case study

    Directory of Open Access Journals (Sweden)

    Stevanović Dimitrije Ž.

    2014-01-01

    Full Text Available Software for chemical processes modeling and simulation, in the past few decades, play an important role in the development of chemical-process industry with their growing capabilities and wide range of application. Usage of process simulators in Serbia for the process design is very limited. This paper gives a brief overview of the numerous process simulators that are used in the chemical-process industry today. The conceptual design is responsible for most of the investment costs in chemical process industry. Importance of precise design on preliminary level is obvious. Wrong decisions made at the conceptual level could be carried out throughout the chain in process design to the detailed design procedures and procurement of equipment. Although preliminary design phase comprises only about 2% of the total cost of the project, it contributes significantly to the reduction of cost of the project by more than 30%. Therefore process simulators play important role in elimination of unnecessary errors in basic process design. Here is also shown a case study of parallel process simulated in different process simulators which tests the results, the reliability and usefulness of these programs in solving specific engineering tasks. Comparison of given simulation results confirm that the modern process simulators are at high level of confidence, no matter they are based on different models, equations, methods, operations, interfaces or data bases. Usage of software speeds up the arrival of optimized solution during the design and the operational procedures. Therefore software have significant impact on reducing time of pre-project phase such as research, conceptual design, and proving project abilities. It’s development lead to faster commercialization of industrial ideas. [Projekat Ministartsva nauke Republike Srbije, br. TR 34009

  17. A verification study and trend analysis of simulated boundary layer wind fields over Europe

    Energy Technology Data Exchange (ETDEWEB)

    Lindenberg, Janna

    2011-07-01

    Simulated wind fields from regional climate models (RCMs) are increasingly used as a surrogate for observations which are costly and prone to homogeneity deficiencies. Compounding the problem, a lack of reliable observations makes the validation of the simulated wind fields a non trivial exercise. Whilst the literature shows that RCMs tend to underestimate strong winds over land these investigations mainly relied on comparisons with near surface measurements and extrapolated model wind fields. In this study a new approach is proposed using measurements from high towers and a robust validation process. Tower height wind data are smoother and thus more representative of regional winds. As benefit this approach circumvents the need to extrapolate simulated wind fields. The performance of two models using different downscaling techniques is evaluated. The influence of the boundary conditions on the simulation of wind statistics is investigated. Both models demonstrate a reasonable performance over flat homogeneous terrain and deficiencies over complex terrain, such as the Upper Rhine Valley, due to a too coarse spatial resolution ({proportional_to}50 km). When the spatial resolution is increased to 10 and 20 km respectively a benefit is found for the simulation of the wind direction only. A sensitivity analysis shows major deviations of international land cover data. A time series analysis of dynamically downscaled simulations is conducted. While the annual cycle and the interannual variability are well simulated, the models are less effective at simulating small scale fluctuations and the diurnal cycle. The hypothesis that strong winds are underestimated by RCMs is supported by means of a storm analysis. Only two-thirds of the observed storms are simulated by the model using a spectral nudging approach. In addition ''False Alarms'' are simulated, which are not detected in the observations. A trend analysis over the period 1961 - 2000 is conducted

  18. The process of adopting and incorporating simulation into undergraduate nursing curricula: a grounded theory study.

    Science.gov (United States)

    Taplay, Karyn; Jack, Susan M; Baxter, Pamela; Eva, Kevin; Martin, Lynn

    2015-01-01

    The aim of this study is to explain the process of adopting and incorporating simulation as a teaching strategy in undergraduate nursing programs, define uptake, and discuss potential outcomes. In many countries, simulation is increasingly adopted as a common teaching strategy. However, there is a dearth of knowledge related to the process of adoption and incorporation. We used an interpretive, constructivist approach to grounded theory to guide this research study. We conducted the study was in Ontario, Canada, during 2011-2012. Using multiple data sources, we informed the development of this theory including in-depth interviews (n = 43) and a review of key organizational documents, such as mission and vision statements (n = 67) from multiple nursing programs (n = 13). The adoption and uptake of mid- to high-fidelity simulation equipment is a multistep iterative process involving various organizational levels within the institution that entails a seven-phase process: (a) securing resources, (b) nursing leaders working in tandem, (c) getting it out of the box, (d) learning about simulation and its potential for teaching, (e) finding a fit, (f) trialing the equipment, and (g) integrating into the curriculum. These findings could assist nursing programs in Canada and internationally that wish to adopt or further incorporate simulation into their curricula and highlight potential organizational and program level outcomes. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

  19. Kinetic step-growth polymerization: A dissipative particle dynamics simulation study.

    Science.gov (United States)

    Xu, Dan; Ni, Chun-Yan; Zhu, You-Liang; Lu, Zhong-Yuan; Xue, Yao-Hong; Liu, Hong

    2018-01-14

    Kinetic step-growth polymerization is studied by dissipative particle dynamics coupled with our previously developed reaction algorithm on a coarse-grained level. The simulation result proves that this step-growth polymerization obeys the second-order reaction kinetics. We apply this algorithm to study the step-growth polymerization using the subunits with different flexibilities or within confinement. Good agreement of the number fraction distributions with the Flory distribution is obtained, implying that this algorithm is reasonable to describe such a kind of step-growth polymerization. This algorithm can further supply a convenient platform for simulating typical step-growth polymerization in reactive polymer systems.

  20. Simulation studies of radiation linewidth in circular Josephson-junction fluxon oscillators

    DEFF Research Database (Denmark)

    If, F.; Christiansen, Peter Leth; Parmentier, R. D.

    1985-01-01

    Detailed simulation studies of the dynamics of fluxons in long circular Josephson tunnel junctions under the influence of external microwave radiation and internal thermal noise are presented. The simulation algorithm uses a pseudospectral method well adapted to vector processors (CRAY-1-S), which...... gives a speed-up factor in computing time of typically 22 in comparison to conventional high-speed computers, and also provides results with a relative accuracy of less than 10-8 thereby making possible the study of the very narrow radiation linewidth of such oscillators. Comparison of calculated...

  1. Simulation Based Studies of Low Latency Teleoperations for NASA Exploration Missions

    Science.gov (United States)

    Gernhardt, Michael L.; Crues, Edwin Z.; Bielski, Paul; Dexter, Dan; Litaker, Harry L.; Chappell, Steven P.; Beaton, Kara H.; Bekdash, Omar S.

    2017-01-01

    Human exploration of Mars will involve both crewed and robotic systems. Many mission concepts involve the deployment and assembly of mission support assets prior to crew arrival on the surface. Some of these deployment and assembly activities will be performed autonomously while others will be performed using teleoperations. However, significant communications latencies between the Earth and Mars make teleoperations challenging. Alternatively, low latency teleoperations are possible from locations in Mars orbit like Mars' moons Phobos and Deimos. To explore these latency opportunities, NASA is conducting a series of studies to investigate the effects of latency on telerobotic deployment and assembly activities. These studies are being conducted in laboratory environments at NASA's Johnson Space Center (JSC), the Human Exploration Research Analog (HERA) at JSC and the NASA Extreme Environment Mission Operations (NEEMO) underwater habitat off the coast of Florida. The studies involve two human-in-the-loop interactive simulations developed by the NASA Exploration Systems Simulations (NExSyS) team at JSC. The first simulation investigates manipulation related activities while the second simulation investigates mobility related activities. The first simulation provides a simple real-time operator interface with displays and controls for a simulated 6 degree of freedom end effector. The initial version of the simulation uses a simple control mode to decouple the robotic kinematic constraints and a communications delay to model latency effects. This provides the basis for early testing with more detailed manipulation simulations planned for the future. Subjects are tested using five operating latencies that represent teleoperation conditions from local surface operations to orbital operations at Phobos, Deimos and ultimately high Martian orbit. Subject performance is measured and correlated with three distance-to-target zones of interest. Each zone represents a target

  2. A preliminary study of a novel emergency department nursing triage simulation for research applications.

    Science.gov (United States)

    Dubovsky, Steven L; Antonius, Daniel; Ellis, David G; Ceusters, Werner; Sugarman, Robert C; Roberts, Renee; Kandifer, Sevie; Phillips, James; Daurignac, Elsa C; Leonard, Kenneth E; Butler, Lisa D; Castner, Jessica P; Richard Braen, G

    2017-01-03

    Studying the effect on functioning of the emergency department of disasters with a potential impact on staff members themselves usually involves table top and simulated patient exercises. Computerized virtual reality simulations have the potential to configure a variety of scenarios to determine likely staff responses and how to address them without intensive utilization of resources. To decide whether such studies are justified, we determined whether a novel computer simulation has the potential to serve as a valid and reliable model of on essential function in a busy ED. Ten experienced female ED triage nurses (mean age 51) mastered navigating a virtual reality model of triage of 4 patients in an ED with which they were familiar, after which they were presented in a testing session with triage of 6 patients whose cases were developed using the Emergency Severity Index to represent a range of severity and complexity. Attitudes toward the simulation, and perceived workload in the simulation and on the job, were assessed with questionnaires and the NASA task load index. Z-scores were calculated for data points reflecting subject actions, the time to perform them, patient prioritization according to severity, and the importance of the tasks. Data from questionnaires and scales were analyzed with descriptive statistics and paired t tests using SPSS v. 21. Microsoft Excel was used to compute a correlation matrix for all standardized variables and all simulation data. Nurses perceived their work on the simulation task to be equivalent to their workload on the job in all aspects except for physical exertion. Although they were able to work with written communications with the patients, verbal communication would have been preferable. Consistent with the workplace, variability in performance during triage reflected subject skill and experience and was correlated with comfort with the task. Time to perform triage corresponded to the time required in the ED and virtual

  3. Accuracy of 3-Dimensional Virtual Surgical Simulation Combined With Digital Teeth Alignment: A Pilot Study.

    Science.gov (United States)

    Kim, Jung-Hoon; Park, Young-Chel; Yu, Hyung-Seog; Kim, Moon-Key; Kang, Sang-Hoon; Choi, Yoon Jeong

    2017-11-01

    To evaluate the accuracy of virtual surgical simulation combined with digital teeth alignment and the applicability of this technique to the diagnosis and establishment of a 3-dimensional (3D) visualized treatment objective for orthognathic surgery by comparing virtual simulation images with actual post-treatment images. This retrospective study included patients who underwent computed tomography (CT) before and after treatment. The 3D digital images were constructed from the initial CT images and dental cast scan data, and virtual surgical simulation combined with digital teeth alignment was performed. Accuracy of the virtual simulation was analyzed by comparing the distances of skeletal and dental landmarks in the horizontal, sagittal, and coronal reference planes with those on post-treatment images using the Wilcoxon signed rank test. Intraclass correlation coefficients were calculated to evaluate the degree of concordance between the 2 images. The study sample included 11 patients (mean age, 18.8 yr). Most landmarks had differences smaller than 2 mm in the 3 reference planes between virtual simulation and post-treatment images; these differences were not statistically significant (P > .05). Most skeletal landmarks, except the A point, B point, and gonion, showed normal to high concordance between the virtual simulation and post-treatment images in the 3 reference planes (P 3D virtual surgical simulation combined with digital teeth alignment using pretreatment CT images yielded results sufficiently accurate to be used for the diagnosis and establishment of visualized treatment objectives for orthognathic surgery. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  4. Development of simulator for studying formation process of crustal structure. 1; Chikaku kozo keisei simulator no kaihatsu. 1

    Energy Technology Data Exchange (ETDEWEB)

    Matsushima, J. [The University of Tokyo, Tokyo (Japan). Faculty of Engineering; Murakami, Y.; Okubo, Y.; Matsubayashi, O.; Tanaka, A.; Nakajima, Y.; Morijiri, R. [Geological Survey of Japan, Tsukuba (Japan); Rokugawa, S. [The University of Tokyo, Tokyo (Japan)

    1997-05-27

    The purpose of this study is to combine seismic activity and volcanic activity by reproducing the formation process of the crustal structure from a physical viewpoint or developing as its extension a numerical simulator which can predict the future. The phenomenon to which attention is especially paid at present is a relation between the dynamic process and the thermal process in the domain including the crust or the upper mantle. Namely, to elucidate the formation process of the crust structure, diastrophism also including seismic activity, igneous activity, etc., it is important to evaluate effects of the behavior of heat supplied from the deep on the dynamic process. In the finite element method, it is not easy to make the effect of gravity reflect to the calculation for boundary conditions. Accordingly, it is general to pay attention to stress difference, considering that stress by gravity is in proportion to static rock pressure stress. Further, to realize interaction between the thermal process and the dynamic process, effects of thermal stress are expressed combining the heat conducting analysis and the plastic flow analysis. 3 refs., 7 figs.

  5. Study of the blowing impact on a hot turbulent boundary layer using Thermal Large Eddy Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Brillant, G. [CEA/Grenoble DEN/DER/SSTH/LMDL, 17 rue des Martyrs 38054, Grenoble Cedex 9 (France); INSA/Centre de Thermique de Lyon (UMR CNRS 5008), Bat. Sadi Carnot 69621, Villeurbanne Cedex (France); Husson, S. [INSA/Centre de Thermique de Lyon (UMR CNRS 5008), Bat. Sadi Carnot 69621, Villeurbanne Cedex (France); Bataille, F. [INSA/Centre de Thermique de Lyon (UMR CNRS 5008), Bat. Sadi Carnot 69621, Villeurbanne Cedex (France)], E-mail: Francoise.Daumas-Bataille@univ-perp.fr; Ducros, F. [CEA/Grenoble DEN/DER/SSTH/LMDL, 17 rue des Martyrs 38054, Grenoble Cedex 9 (France)

    2008-12-15

    We investigate Thermal Large Eddy Simulation in a complex case using Trio U. We develop a thermal turbulent inflow condition based on parallel flows in order to simulate a turbulent thermal boundary layer. This inflow condition is tested with a turbulent channel flow. We show that it produces fine profiles for velocity and temperature. Later, this inlet condition is used in the case of blowing through a porous plate. Two different blowing regimes are studied: the classical turbulent boundary layer and the blown off boundary layer. Comparisons show that we obtain similar experimental and numerical profiles (Brillant, G., Husson, S., Bataille, F., 2008. Experimental study of the blowing impact on a hot turbulent boundary layer. International Journal of Heat and Mass Transfer 51 (7-8), 1996-2005.). We finish with additional results obtained only through numerical simulations.

  6. Comparative usability studies of full vs. partial immersive virtual reality simulation for medical education and training.

    Science.gov (United States)

    Pierce, Jennifer; Gutiérrez, Fátima; Vergara, Víctor M; Alverson, Dale C; Qualls, Clifford; Saland, Linda; Goldsmith, Timothy; Caudell, Thomas Preston

    2008-01-01

    Virtual reality (VR) simulation provides a means of making experiential learning reproducible and reusable. This study was designed to determine the efficiency and satisfaction components of usability. Previously, it was found that first year medical students using a VR simulation for medical education demonstrated effectiveness in learning as measured by knowledge structure improvements both with and without a head mounted display (HMD) but students using a HMD showed statistically greater improvement in knowledge structures compared to those not using a HMD. However, in this current analysis of other components of usability, there were no overall significance differences in efficiency (ease of use), nor in satisfaction, within this same group of randomized subjects comparing students using a HMD to those not using a HMD. These types of studies may be important in determining the most appropriate, cost effective VR simulation technology needed to achieve specific learning goals and objectives.

  7. CO2 capture using aqueous ammonia: kinetic study and process simulation

    DEFF Research Database (Denmark)

    Darde, Victor Camille Alfred; van Well, Willy J.M.; Stenby, Erling Halfdan

    2011-01-01

    Carbon dioxide capture using aqueous ammonia is a post-combustion technology that has shown a good potential. Therefore this process is studied by measuring the rate of absorption of carbon dioxide by aqueous ammonia and by performing process simulation. The rate of absorption of carbon dioxide...... by aqueous ammonia solvent has been studied by applying a wetted wall column apparatus. The rate of absorption is crucial regarding the sizing of the absorber columns. The overall mass transfer coefficient has been measured at temperatures from 279 to 304 K for 1 to 10 wt% ammonia solutions at loadings up...... to 0.6. The results were compared with those found for 30 wt% mono-ethanolamine (MEA) solutions.The capture process was simulated successfully using the simulator Aspen Plus coupled with the extended UNIQUAC thermodynamic model available for the NH3–CO2–H2O system. For this purpose, a user model...

  8. Recommendations for the Conduct and Reporting of Modeling and Simulation Studies in Health Technology Assessment.

    Science.gov (United States)

    Dahabreh, Issa J; Trikalinos, Thomas A; Balk, Ethan M; Wong, John B

    2016-10-18

    Models and simulations are valuable tools for addressing the uncertainty, tradeoffs, and heterogeneous preferences that complicate research questions in health technology assessment. This article presents recommendations for the conduct and reporting of modeling and simulation studies based on a systematic review of published recommendation statements, a survey of Web sites of international health technology assessment organizations, and input from experts and other stakeholders. The recommendations apply to mathematical models that represent structural relationships among model components and integrate information from multiple sources; they address model identification, estimation, verification, and validation, as well as the conduct of sensitivity, stability, and uncertainty analyses. They are organized into model conceptualization and structure, data, model assessment and consistency, and interpreting and reporting results. They should contribute to increased use and better conduct and reporting of modeling and simulation studies in health technology assessment.

  9. 42: An Open-Source Simulation Tool for Study and Design of Spacecraft Attitude Control Systems

    Science.gov (United States)

    Stoneking, Eric

    2018-01-01

    Simulation is an important tool in the analysis and design of spacecraft attitude control systems. The speaker will discuss the simulation tool, called simply 42, that he has developed over the years to support his own work as an engineer in the Attitude Control Systems Engineering Branch at NASA Goddard Space Flight Center. 42 was intended from the outset to be high-fidelity and powerful, but also fast and easy to use. 42 is publicly available as open source since 2014. The speaker will describe some of 42's models and features, and discuss its applicability to studies ranging from early concept studies through the design cycle, integration, and operations. He will outline 42's architecture and share some thoughts on simulation development as a long-term project.

  10. Hydrologic Simulations Driven by Satellite Rainfall to Study the Hydroelectric Development Impacts on River Flow

    Directory of Open Access Journals (Sweden)

    Tuan B. Le

    2014-11-01

    Full Text Available This study assesses the impact of hydroelectric dams on the discharge and total suspended solids (TSS concentration in the Huong River basin in Vietnam. The analysis is based on hydrologic and sediment transport simulations by the Soil and Water Assessment Tool (SWAT model driven by the Tropical Rainfall Measuring Mission (TRMM 3B42V6 rainfall data, from January 2003 through December 2010. An upstream sub-basin not affected by the hydroelectric dams was used for model calibration. The calibration results indicate good agreement between simulated and observed daily data (0.67 Nash-Sutcliffe efficiency, 0.82 Pearson correlation coefficient. The calibrated model for discharge and TSS simulation is then applied on another major sub-basin and then the whole Huong River basin. The simulation results indicate that dam operation in 2010 decreased downstream discharge during the rainy season by about 35% and augmented it during the dry season by about 226%. The downstream TSS concentration has decreased due to the dam operation but the total sediment loading increased during the dry season and decreased during the rainy season. On average, the dam construction and operation affected the pattern of discharge more than that of the sediment loading. Results indicate that SWAT, driven by remotely sensed inputs, can reasonably simulate discharge and water quality in ungauged or poorly gauged river basins and can be very useful for water resources assessment and climate change impact studies in such basins.

  11. Validation study of gyrokinetic simulation (GYRO) near the edge in Alcator C-Mod ohmic discharges

    Science.gov (United States)

    Sung, C.; White, A.; Howard, N.; Mikkelsen, D.; Holland, C.; Rice, J.; Reinke, M.; Gao, C.; Ennever, P.; Porkolab, M.; Churchill, R.; Theiler, C.; Walk, J.; Hughes, J.; Hubbard, A.; Greenwald, M.

    2014-10-01

    A validation study of local gyrokinetic simulations (GYRO) near the edge region (r / a ~ 0 . 85) has been performed for two C-Mod ohmic discharges, namely one that is in the Linear Ohmic Confinement (LOC) regime and the other one in the Saturated Ohmic Confinement (SOC) regime. Comparing the simulated heat fluxes and synthetic Te fluctuations with the experiments, it is found that GYRO can reproduce the ion heat flux and the Te fluctuation level measured by the Correlation ECE (CECE) diagnostic within their uncertainties, while the simulated electron heat flux is under-predicted. Furthermore, the synthetic Te spectral shape is not matched with the measured spectrum in both LOC/SOC discharges. We have also performed global simulations to consider the interaction of turbulence within the sampling volume of the CECE diagnostic, enabling us to evaluate the importance of global simulations in applying a synthetic CECE diagnostic in this study. The LOC/SOC transition physics will be also explored. Research supported by USDoE Awards DE-SC0006419, DE-FC02-99ER54512.

  12. Use of virtual clinical simulation to improve communication skills of baccalaureate nursing students: a pilot study.

    Science.gov (United States)

    Foronda, Cynthia; Gattamorta, Karina; Snowden, Kenya; Bauman, Eric B

    2014-06-01

    According to The Joint Commission (2012), the leading cause of sentinel events in the United States was miscommunication. Lack of thorough and accurate communication remains a serious challenge in healthcare and an educational priority in schools of nursing. Virtual clinical simulation is an online educational approach where students use avatars to practice various skills. The purpose of this pilot study was to evaluate the educational innovation of using virtual clinical simulation to improve communication skills of BSN students. The objectives of the simulations were to 1) recognize significant patient data and 2) accurately perform the ISBAR communication technique. The study used a within-group, time-series design with eight students. Students participated in two synchronous virtual simulations in an online virtual clinical environment called CliniSpace. Students performed in groups of four to five students. Students performed in two virtual simulations in groups of four to five students. Student performances were scored by two raters using the CliniSpace ISBAR Rating Sheet. Field notes from debriefing sessions were analyzed for content. Mean group student performance scores more than doubled from performance one to performance two. This change was found to be statistically significant, pstudents listened to how their peers communicated and learned from them. Students expressed having less anxiety, knowing what to expect, and having "better flow" with communication. Students verbalized learning to assess the patient prior to calling the physician and to give a recommendation to the physician. © 2013.

  13. The effect of simulation courseware on critical thinking in undergraduate nursing students: multi-site pre-post study.

    Science.gov (United States)

    Shin, Hyunsook; Ma, Hyunhee; Park, Jiyoung; Ji, Eun Sun; Kim, Dong Hee

    2015-04-01

    The use of simulations has been considered as opportunities for students to enhance their critical thinking (CT), but previous studies were limited because they did not provide in-depth information on the working dynamics of simulation or on the effects of the number of simulation exposures on CT. This study examined the effect of an integrated pediatric nursing simulation used in a nursing practicum on students' CT abilities and identified the effects of differing numbers of simulation exposures on CT in a multi-site environment. The study used a multi-site, pre-test, post-test design. A total of 237 nursing students at three universities enrolled in a pediatric practicum participated in this study from February to December 2013. All three schools used the same simulation courseware, including the same simulation scenarios, evaluation tools, and simulation equipment. The courseware incorporated high-fidelity simulators and standardized patients. Students at school A completed one simulation session, whereas students at schools B and C completed two and three simulation sessions, respectively. Yoon's Critical Thinking Disposition tool (2008) was used to measure students' CT abilities. The gains in students' CT scores varied according to their numbers of exposures to the simulation courseware. With a single exposure, there were no statistically significant gains in CT, whereas three exposures to the courseware produced significant gains in CT. In seven subcategories of critical thinking, three exposures to the simulation courseware produced CT gains in the prudence and intellectual eagerness subcategories, and the overall simulation experience produced CT gains in the prudence, systematicity, healthy skepticism, and intellectual eagerness subcategories. Simulation courseware may produce positive learning outcomes for prudence in nursing education. In addition, the findings from the multi-site comparative study may contribute to greater understanding of how patient

  14. [3D Virtual Reality Laparoscopic Simulation in Surgical Education - Results of a Pilot Study].

    Science.gov (United States)

    Kneist, W; Huber, T; Paschold, M; Lang, H

    2016-06-01

    The use of three-dimensional imaging in laparoscopy is a growing issue and has led to 3D systems in laparoscopic simulation. Studies on box trainers have shown differing results concerning the benefit of 3D imaging. There are currently no studies analysing 3D imaging in virtual reality laparoscopy (VRL). Five surgical fellows, 10 surgical residents and 29 undergraduate medical students performed abstract and procedural tasks on a VRL simulator using conventional 2D and 3D imaging in a randomised order. No significant differences between the two imaging systems were shown for students or medical professionals. Participants who preferred three-dimensional imaging showed significantly better results in 2D as wells as in 3D imaging. First results on three-dimensional imaging on box trainers showed different results. Some studies resulted in an advantage of 3D imaging for laparoscopic novices. This study did not confirm the superiority of 3D imaging over conventional 2D imaging in a VRL simulator. In the present study on 3D imaging on a VRL simulator there was no significant advantage for 3D imaging compared to conventional 2D imaging. Georg Thieme Verlag KG Stuttgart · New York.

  15. A simulation study of capacity utilization to predict future capacity for manufacturing system sustainability

    Science.gov (United States)

    Rimo, Tan Hauw Sen; Chai Tin, Ong

    2017-12-01

    Capacity utilization (CU) measurement is an important task in a manufacturing system, especially in make-to-order (MTO) type manufacturing system with product customization, in predicting capacity to meet future demand. A stochastic discrete-event simulation is developed using ARENA software to determine CU and capacity gap (CG) in short run production function. This study focused on machinery breakdown and product defective rate as random variables in the simulation. The study found that the manufacturing system run in 68.01% CU and 31.99% CG. It is revealed that machinery breakdown and product defective rate have a direct relationship with CU. By improving product defective rate into zero defect, manufacturing system can improve CU up to 73.56% and CG decrease to 26.44%. While improving machinery breakdown into zero breakdowns will improve CU up to 93.99% and the CG decrease to 6.01%. This study helps operation level to study CU using “what-if” analysis in order to meet future demand in more practical and easier method by using simulation approach. Further study is recommended by including other random variables that affect CU to make the simulation closer with the real-life situation for a better decision.

  16. A comparison of different estimation methods for simulation-based sample size determination in longitudinal studies

    Science.gov (United States)

    Bahçecitapar, Melike Kaya

    2017-07-01

    Determining sample size necessary for correct results is a crucial step in the design of longitudinal studies. Simulation-based statistical power calculation is a flexible approach to determine number of subjects and repeated measures of longitudinal studies especially in complex design. Several papers have provided sample size/statistical power calculations for longitudinal studies incorporating data analysis by linear mixed effects models (LMMs). In this study, different estimation methods (methods based on maximum likelihood (ML) and restricted ML) with different iterative algorithms (quasi-Newton and ridge-stabilized Newton-Raphson) in fitting LMMs to generated longitudinal data for simulation-based power calculation are compared. This study examines statistical power of F-test statistics for parameter representing difference in responses over time from two treatment groups in the LMM with a longitudinal covariate. The most common procedures in SAS, such as PROC GLIMMIX using quasi-Newton algorithm and PROC MIXED using ridge-stabilized algorithm are used for analyzing generated longitudinal data in simulation. It is seen that both procedures present similar results. Moreover, it is found that the magnitude of the parameter of interest in the model for simulations affect statistical power calculations in both procedures substantially.

  17. A High-Level MultiFunction Radar Simulation for Studying the Performance of MultiSensor Data Fusion Systems

    NARCIS (Netherlands)

    Huizing, A.G.; Bossee, E.

    1998-01-01

    This paper presents the basic requirements for a simulation of the main capabilities of a shipborne MultiFunction Radar (MFR) that can be used in conjunction with other sensor simulations in scenarios for studying Multi Sensor Data Fusion (MSDF) systems. This simulation is being used to support an

  18. Case Study: An Examination of the Decision Making Process for Selecting Simulations for an Online MBA Program

    Science.gov (United States)

    Neely, Pat; Tucker, Jan

    2013-01-01

    Purpose: Simulations are designed as activities which imitate real world scenarios and are often used to teach and enhance skill building. The purpose of this case study is to examine the decision making process and outcomes of a faculty committee tasked with examining simulations in the marketplace to determine if the simulations could be used as…

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

    Science.gov (United States)

    Poikela, Paula; Ruokamo, Heli; Teräs, Marianne

    2015-02-01

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

  20. Co-producing simulation models to inform resource management: a case study from southwest South Dakota

    Science.gov (United States)

    Miller, Brian W.; Symstad, Amy J.; Frid, Leonardo; Fisichelli, Nicholas A.; Schuurman, Gregor W.

    2017-01-01

    Simulation models can represent complexities of the real world and serve as virtual laboratories for asking “what if…?” questions about how systems might respond to different scenarios. However, simulation models have limited relevance to real-world applications when designed without input from people who could use the simulated scenarios to inform their decisions. Here, we report on a state-and-transition simulation model of vegetation dynamics that was coupled to a scenario planning process and co-produced by researchers, resource managers, local subject-matter experts, and climate change adaptation specialists to explore potential effects of climate scenarios and management alternatives on key resources in southwest South Dakota. Input from management partners and local experts was critical for representing key vegetation types, bison and cattle grazing, exotic plants, fire, and the effects of climate change and management on rangeland productivity and composition given the paucity of published data on many of these topics. By simulating multiple land management jurisdictions, climate scenarios, and management alternatives, the model highlighted important tradeoffs between grazer density and vegetation composition, as well as between the short- and long-term costs of invasive species management. It also pointed to impactful uncertainties related to the effects of fire and grazing on vegetation. More broadly, a scenario-based approach to model co-production bracketed the uncertainty associated with climate change and ensured that the most important (and impactful) uncertainties related to resource management were addressed. This cooperative study demonstrates six opportunities for scientists to engage users throughout the modeling process to improve model utility and relevance: (1) identifying focal dynamics and variables, (2) developing conceptual model(s), (3) parameterizing the simulation, (4) identifying relevant climate scenarios and management

  1. Evolution of stress in anaesthesia registrars with repeated simulated courses: An observational study.

    Science.gov (United States)

    Gouin, Antoine; Damm, Cédric; Wood, Grégory; Cartier, Sébastien; Borel, Marie; Villette-Baron, Karen; Boet, Sylvain; Compère, Vincent; Dureuil, Bertrand

    2017-02-01

    High-fidelity medical simulation is a source of stress for participants. The aim of this study was to assess if repeated simulated courses decrease perceived stress and/or physiological stress level and increase performance in anaesthesiology registrars. Fourteen anaesthesiology specialty registrars participated individually in three successive sessions of crisis simulation in the operating room. Participants' perceived stress levels were measured by self-assessment (simple numerical scale from 0 to 10 [0=no stress, 10=maximum stress]) and physiological stress was estimated via the maximal heart rate measured by a Holter system). Technical and non-technical performances were also assessed. Data are expressed as medians with interquartile ranges and extremes (median (IQR [Min-Max])). Between the first and third session, simulation repetition was associated with a decrease in perceived stress (9 (8-10 [5-10]) versus 7 (5-8 [2-9]) from session 1 to session 3 respectively, P=0.02), whereas physiological stress assessed by the maximum heart rate remained unchanged (130 beats per minute (116-141 [85-170]) and 123 beats per minute (115-136 [88-166]) between sessions 1 and 3 respectively). There was also a significant inverse correlation between perceived stress levels experienced by registrars during the session and non-technical performance (P=0.008). We observed a reduction in perceived stress levels experienced by registrars while physiological stress was unchanged with repeating simulation sessions combining simulated practice and debriefing. Learning through simulation could improve perceived stress management in critical situations. Copyright © 2016 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.

  2. A simulation study provided sample size guidance for differential item functioning (DIF) studies using short scales

    DEFF Research Database (Denmark)

    Scott, Neil W; Fayers, Peter M; Aaronson, Neil K

    2009-01-01

    Differential item functioning (DIF) analyses are increasingly used to evaluate health-related quality of life (HRQoL) instruments, which often include relatively short subscales. Computer simulations were used to explore how various factors including scale length affect analysis of DIF by ordinal...

  3. A simulation study provided sample size guidance for differential item functioning (DIF) studies using short scales

    NARCIS (Netherlands)

    Scott, Neil W.; Fayers, Peter M.; Aaronson, Neil K.; Bottomley, Andrew; de Graeff, Alexander; Groenvold, Mogens; Gundy, Chad; Koller, Michael; Petersen, Morten A.; Sprangers, Mirjam A. G.

    Objective: Differential item functioning (DIF) analyses are increasingly used to evaluate health-related quality of life (HRQoL) instruments, which often include relatively short subscales. Computer simulations were used to explore how various factors including scale length affect analysis of DIF by

  4. A simulation study of acoustic-assisted tracking of whales for mark-recapture surveys.

    Directory of Open Access Journals (Sweden)

    David Peel

    Full Text Available Collecting enough data to obtain reasonable abundance estimates of whales is often difficult, particularly when studying rare species. Passive acoustics can be used to detect whale sounds and are increasingly used to estimate whale abundance. Much of the existing effort centres on the use of acoustics to estimate abundance directly, e.g. analysing detections in a distance sampling framework. Here, we focus on acoustics as a tool incorporated within mark-recapture surveys. In this context, acoustic tools are used to detect and track whales, which are then photographed or biopsied to provide data for mark-recapture analyses. The purpose of incorporating acoustics is to increase the encounter rate beyond using visual searching only. While this general approach is not new, its utility is rarely quantified. This paper predicts the "acoustically-assisted" encounter rate using a discrete-time individual-based simulation of whales and survey vessel. We validate the simulation framework using existing data from studies of sperm whales. We then use the framework to predict potential encounter rates in a study of Antarctic blue whales. We also investigate the effects of a number of the key parameters on encounter rate. Mean encounter rates from the simulation of sperm whales matched well with empirical data. Variance of encounter rate, however, was underestimated. The simulation of Antarctic blue whales found that passive acoustics should provide a 1.7-3.0 fold increase in encounter rate over visual-only methods. Encounter rate was most sensitive to acoustic detection range, followed by vocalisation rate. During survey planning and design, some indication of the relationship between expected sample size and effort is paramount; this simulation framework can be used to predict encounter rates and establish this relationship. For a case in point, the simulation framework indicates unequivocally that real-time acoustic tracking should be considered for

  5. Large shear deformation of particle gels studied by Brownian Dynamics simulations

    NARCIS (Netherlands)

    Rzepiela, A.A.; Opheusden, van J.H.J.; Vliet, van T.

    2004-01-01

    Brownian Dynamics (BD) simulations have been performed to study structure and rheology of particle gels under large shear deformation. The model incorporates soft spherical particles, and reversible flexible bond formation. Two different methods of shear deformation are discussed, namely affine and

  6. Prototype, mesoscale simulator for the study of oil weathering under severe conditions

    National Research Council Canada - National Science Library

    Pelletier, Emilien; Brochu, C. J

    1987-01-01

    As long-term, open-sea tests on oil weathering could be difficult and experiments in ice in the field even impossible to manage, chose to develop low-cost simulation tank with which to study long-term fate...

  7. Where do the platelets go? A simulation study of fully resolved blood flow through aneurysmal vessels

    NARCIS (Netherlands)

    Mountrakis, L.; Lorenz, E.; Hoekstra, A.G.

    2013-01-01

    Despite the importance of platelets in the formation of a thrombus, their transport in complex flows has not yet been studied in detail. In this paper we simulated red blood cells and platelets to explore their transport behaviour in aneurysmal geometries. We considered two aneurysms with different

  8. Simulation studies on the effect of a buffer layer on the external ...

    Indian Academy of Sciences (India)

    Device modeling of –– junction amorphous silicon solar cells has been carried out using the amorphous semiconductor analysis (ASA) simulation programme. The aim of the study was to explain the role of a buffer layer in between the - and -layers of the –– solar cell on the external parameters such as dark ...

  9. Self-diffusion in the hexagonal structure of Zirconium and Hafnium: computer simulation studies

    Directory of Open Access Journals (Sweden)

    Diego Hernán Ruiz

    2005-12-01

    Full Text Available Self-diffusion by vacancy mechanism is studied in two metals of hexagonal close packed structure, namely Hafnium and Zirconium. Computer simulation techniques are used together with many-body potentials of the embedded atom type. Defect properties are calculated at 0 K by molecular static while molecular dynamic is used to explore a wide temperature range.

  10. An Overview and Study on the Use of Games, Simulations, and Gamification in Higher Education

    Science.gov (United States)

    Wiggins, Bradley E.

    2016-01-01

    This article examines the use of both game-based learning (GBL) and gamification in tertiary education. This study focuses specifically on the use of games and/or simulations as well as familiarity with gamification strategies by communication faculty. Research questions concentrate on the rate, frequency, and usage of digital and non-digital…

  11. Magnetic force microscopy and simulation studies on Co50Fe50 ...

    Indian Academy of Sciences (India)

    Abstract. We studied the magnetization reversal mechanism of single-layered Co50Fe50 nanomagnets by mea- suring the magnetization reversal and using the micromagnetic simulations. The magnetization reversal strongly depends on the thickness of the nanomagnets. In the remanent state, the magnetic force ...

  12. Assessing Critical Thinking Outcomes of Dental Hygiene Students Utilizing Virtual Patient Simulation: A Mixed Methods Study.

    Science.gov (United States)

    Allaire, Joanna L

    2015-09-01

    Dental hygiene educators must determine which educational practices best promote critical thinking, a quality necessary to translate knowledge into sound clinical decision making. The aim of this small pilot study was to determine whether virtual patient simulation had an effect on the critical thinking of dental hygiene students. A pretest-posttest design using the Health Science Reasoning Test was used to evaluate the critical thinking skills of senior dental hygiene students at The University of Texas School of Dentistry at Houston Dental Hygiene Program before and after their experience with computer-based patient simulation cases. Additional survey questions sought to identify the students' perceptions of whether the experience had helped develop their critical thinking skills and improved their ability to provide competent patient care. A convenience sample of 31 senior dental hygiene students completed both the pretest and posttest (81.5% of total students in that class); 30 senior dental hygiene students completed the survey on perceptions of the simulation (78.9% response rate). Although the results did not show a significant increase in mean scores, the students reported feeling that the use of virtual patients was an effective teaching method to promote critical thinking, problem-solving, and confidence in the clinical realm. The results of this pilot study may have implications to support the use of virtual patient simulations in dental hygiene education. Future research could include a larger controlled study to validate findings from this study.

  13. Addressing the Problem of Switched Class Labels in Latent Variable Mixture Model Simulation Studies

    Science.gov (United States)

    Tueller, Stephen J.; Drotar, Scott; Lubke, Gitta H.

    2011-01-01

    The discrimination between alternative models and the detection of latent classes in the context of latent variable mixture modeling depends on sample size, class separation, and other aspects that are related to power. Prior to a mixture analysis it is useful to investigate model performance in a simulation study that reflects the research…

  14. Large eddy simulation studies of the effects of alignment and wind farm length

    NARCIS (Netherlands)

    Stevens, Richard Johannes Antonius Maria; Gayme, Dennice F.; Meneveau, Charles

    2014-01-01

    Large eddy simulations of wind farms are performed to study the effects of wind turbine row alignment with respect to the incoming flow direction. Various wind farms with fixed stream-wise spacing (7.85 rotor diameters) and varying lateral displacements and span-wise turbine spacings are considered,

  15. Promoting Collaboration in Health Care Teams through Interprofessional Education: A Simulation Case Study

    Science.gov (United States)

    Ekmekci, Ozgur

    2013-01-01

    This simulation study explores how the integration of interprofessional components into health care curriculum may impact professional stereotyping and collaborative behavior in care delivery teams comprised of a physician, a registered nurse, a physician's assistant, a physical therapist, and a radiation therapist. As part of the agent-based…

  16. Table 1. Description of samples used for simulation study with S1, 2 ...

    Indian Academy of Sciences (India)

    priyanka

    Description of samples used for simulation study with S1, 2, 3. Sample name Treatment_time Treatment_agent Sample source. GEO sample. (GSM) file Ids. 1. Lm_Adult1. 0 h. Listeria monocytogenes. Peripheral blood. GSM1467819. 2 h. GSM1467820. 6 h. GSM1467821. 2. Lm_Adult2. 0 h. Peripheral blood. GSM1467822.

  17. Effects of steering demand on lane keeping behaviour, self-reports, and physiology : A simulator study

    NARCIS (Netherlands)

    Dijksterhuis, Chris; Brookhuis, Karel A.; De Waard, Dick

    In this study a driving simulator was used to determine changes in mental effort in response to manipulations of steering demand. Changes in mental effort were assessed by using subjective effort ratings, physiology, and the standard deviation of the lateral position. Steering demand was increased

  18. A Theory for the Neural Basis of Language Part 2: Simulation Studies of the Model

    Science.gov (United States)

    Baron, R. J.

    1974-01-01

    Computer simulation studies of the proposed model are presented. Processes demonstrated are (1) verbally directed recall of visual experience; (2) understanding of verbal information; (3) aspects of learning and forgetting; (4) the dependence of recognition and understanding in context; and (5) elementary concepts of sentence production. (Author)

  19. Ethics Case-Study Simulation: A Generic Tool for Psychology Teachers.

    Science.gov (United States)

    McMinn, Mark R.

    1988-01-01

    Describes a case-study simulation program designed to assist instructors in teaching ethics in psychology. Concludes that the program is useful for teaching ethics as it reveals the difficulty of ethical decision-making and generates, through student work, discussions on the moral bases for different ethical decisions. (Author/GEA)

  20. Numerical Simulations of Kinetic Alfvén Waves to Study Spectral ...

    Indian Academy of Sciences (India)

    Index in Solar Wind Turbulence and Particle Heating. R. P. Sharma. ∗. & H. D. Singh. Center for Energy Studies, Indian Institute of Technology, Delhi 110 016, India. ∗ e-mail: rpsharma@ces.iitd.ernet.in. Abstract. We present numerical simulations of the modified nonlinear. Schrödinger equation satisfied by kinetic Alfvén ...

  1. Debriefing after High-Fidelity Simulation and Knowledge Retention: A Quasi-Experimental Study

    Science.gov (United States)

    Olson, Susan L.

    2013-01-01

    High-fidelity simulation (HFS) use in nursing education has been a frequent research topic in recent years. Previous research included studies on the use of HFS with nursing students, focusing on their feelings of self-confidence and anxiety. However, research focused specifically on the debriefing portion of HFS was limited. This quantitative,…

  2. Methods to Estimate the Variance of Some Indices of the Signal Detection Theory: A Simulation Study

    Science.gov (United States)

    Suero, Manuel; Privado, Jesús; Botella, Juan

    2017-01-01

    A simulation study is presented to evaluate and compare three methods to estimate the variance of the estimates of the parameters d and "C" of the signal detection theory (SDT). Several methods have been proposed to calculate the variance of their estimators, "d'" and "c." Those methods have been mostly assessed by…

  3. Ergonomic study regarding sport training – Push-ups simulation and analysis

    Directory of Open Access Journals (Sweden)

    Ion S. BOROZAN

    2012-06-01

    Full Text Available Some of the most common and helpful physical exercises used in sport training are the push-ups. Their biomechanics is analyzed in the paper and the author also gives an ergonomical study of this particular exercise with a complete simulation of the process.

  4. Testing the Intervention Effect in Single-Case Experiments: A Monte Carlo Simulation Study

    Science.gov (United States)

    Heyvaert, Mieke; Moeyaert, Mariola; Verkempynck, Paul; Van den Noortgate, Wim; Vervloet, Marlies; Ugille, Maaike; Onghena, Patrick

    2017-01-01

    This article reports on a Monte Carlo simulation study, evaluating two approaches for testing the intervention effect in replicated randomized AB designs: two-level hierarchical linear modeling (HLM) and using the additive method to combine randomization test "p" values (RTcombiP). Four factors were manipulated: mean intervention effect,…

  5. Contribution of seasonality in transmission of Mycrobacterium tuberculosis to seasonality in tuberculosis disease: a simulation study

    NARCIS (Netherlands)

    Soetens, L.C.; Boshuizen, H.C.; Korthals Altes, H.

    2013-01-01

    A seasonal rise in tuberculosis (TB) notifications has been confirmed in several studies. Here, we examined one hypothesis for its cause: increased transmission of TB during wintertime due to crowding. Seasonality analysis was performed on actual and simulated notifications of clustered TB cases,

  6. The Statistical Power of the Cluster Randomized Block Design with Matched Pairs--A Simulation Study

    Science.gov (United States)

    Dong, Nianbo; Lipsey, Mark

    2010-01-01

    This study uses simulation techniques to examine the statistical power of the group- randomized design and the matched-pair (MP) randomized block design under various parameter combinations. Both nearest neighbor matching and random matching are used for the MP design. The power of each design for any parameter combination was calculated from…

  7. Genetic analysis of tolerance to infections using random regressions: a simulation study

    NARCIS (Netherlands)

    Kause, A.

    2011-01-01

    Tolerance to infections is the ability of a host to limit the impact of a given pathogen burden on host performance. This simulation study demonstrated the merit of using random regressions to estimate unbiased genetic variances for tolerance slope and its genetic correlations with other traits,

  8. Salinity effects on fruit yield in vegetable crops : a simulation study

    NARCIS (Netherlands)

    Heuvelink, E.; Bakker, M.J.; Stanghellini, C.

    2003-01-01

    Salinity can reduce crop growth and yield through its impact on plant water relations by: (1) increased fruit dry matter content, (2) reduced leaf expansion and (3) stomatal closure. In this simulation study the tomato model TOMSIM was used to predict salinity impact on fruit fresh yield, based on

  9. PEPT and discrete particle simulation study of spout-fluid bed regimes

    NARCIS (Netherlands)

    Link, J.M.; Deen, N.G.; Kuipers, J.A.M.; Fan, X.; Ingram, A.; Parker, D.J.; Wood, J.; Seville, J.P.K.

    2008-01-01

    The results of a combined experimental and simulation study on the flow regimes that can be encountered during spout-fluid bed operation are reported. A regime map for a three-dimensional (3D) spout-fluid bed was composed, employing spectral analysis of pressure drop fluctuations and fast video

  10. A simulation study of spectral Čerenkov luminescence imaging for tumour margin estimation

    Science.gov (United States)

    Calvert, Nick; Helo, Yusef; Mertzanidou, Thomy; Tuch, David S.; Arridge, Simon R.; Stoyanov, Danail

    2017-03-01

    Breast cancer is the most common cancer in women in the world. Breast-conserving surgery (BCS) is a standard surgical treatment for breast cancer with the key objective of removing breast tissue, maintaining a negative surgical margin and providing a good cosmetic outcome. A positive surgical margin, meaning the presence of cancerous tissues on the surface of the breast specimen after surgery, is associated with local recurrence after therapy. In this study, we investigate a new imaging modality based on Cerenkov luminescence imaging (CLI) for the purpose of detecting positive surgical margins during BCS. We develop Monte Carlo (MC) simulations using the Geant4 nuclear physics simulation toolbox to study the spectrum of photons emitted given 18F-FDG and breast tissue properties. The resulting simulation spectra show that the CLI signal contains information that may be used to estimate whether the cancerous cells are at a depth of less than 1 mm or greater than 1 mm given appropriate imaging system design and sensitivity. The simulation spectra also show that when the source is located within 1 mm of the surface, the tissue parameters are not relevant to the model as the spectra do not vary significantly. At larger depths, however, the spectral information varies significantly with breast optical parameters, having implications for further studies and system design. While promising, further studies are needed to quantify the CLI response to more accurately incorporate tissue specific parameters and patient specific anatomical details.

  11. Human Cadavers vs. Multimedia Simulation: A Study of Student Learning in Anatomy

    Science.gov (United States)

    Saltarelli, Andrew J.; Roseth, Cary J.; Saltarelli, William A.

    2014-01-01

    Multimedia and simulation programs are increasingly being used for anatomy instruction, yet it remains unclear how learning with these technologies compares with learning with actual human cadavers. Using a multilevel, quasi-experimental-control design, this study compared the effects of "Anatomy and Physiology Revealed" (APR) multimedia…

  12. Studies on the survival of Ascaris suum eggs under laboratory and simulated field conditions

    NARCIS (Netherlands)

    Gaasenbeek, C.P.H.; Borgsteede, F.H.M.

    1998-01-01

    A series of four experiments was carried out to study the survival of Ascaris suum eggs: in a pig slurry unit on a farm, in the laboratory under anaerobic conditions and different relative humidities (rH), and under simulated field conditions. Survival of eggs in the pig slurry unit was 20% after

  13. A comparative study of psychophysiological reactions during simulator and real flight

    NARCIS (Netherlands)

    Veltman, J.A.

    2002-01-01

    During selection tests in a flight simulator and a real aircraft, physiological workload measures were evaluated. The selection context guaranteed high motivation in the participant to exert additional effort during difficult flight tasks. The aim of the study was to obtain information about the

  14. Validation study of a ray-tracing simulator for focal construct geometry.

    Science.gov (United States)

    Dicken, Anthony; Rogers, Keith; Godber, Simon; Prokopiou, Danae; Shevchuk, Alex; Tranfield, Graham; Evans, Paul

    2014-12-01

    We present the results of a computer modelling package designed to simulate X-ray diffraction imaging employing focal construct geometry. The paths of coherently diffracted X-rays are modelled by ray-tracing. The results of the study show good agreement between simulated and measured data obtained in the laboratory. The validation of the modelling package permits the rapid optimisation and prototyping of focal construct technology, which has wide applicability in security X-ray imaging. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Simulation of fruit pallet movement in the port of Durban: A case study

    CSIR Research Space (South Africa)

    Van Dyk, FE

    2005-04-01

    Full Text Available of forklifts Expected value Scenario analysis Table 1: Output parameters estimated in the simulation study. The following scenarios were simulated, namely (I) the effect of an increase in fruit exported through the port and (II) the effect of an investment... is not supposed to absorb fruit pallets due to external inefficiencies, although some capacity allowances should be made for unforeseen events, e.g. bad weather. • The forklifts, cranes and other equipment were assumed to be ideal, i.e. no equipment failures...

  16. Simulation platform developed to study and identify critical cases in a future smart grid

    DEFF Research Database (Denmark)

    Mihet-Popa, Lucian; Zong, Yi; You, Shi

    2016-01-01

    simulation and planning tools, with a particular objective on the challenges faced by the introduction of Smart Grid technologies. Another important issue of the paper is to identify critical load cases, as well as the voltage variations with the highest potential, able to implement the grid model......This paper proposes a simulation platform developed to study and identify critical cases in a Smart Grid. A distribution network with different Distributed Energy Resources (DER) components, connected along the feeders, is analyzed, having the objective to identify limitations of existing...

  17. Acoustic hemostasis of porcine superficial femoral artery: Simulation and in-vivo experimental studies

    Science.gov (United States)

    Zeng, Xiaozheng; Mitchell, Stuart; Miller, Matthew; Barnes, Stephen; Hopple, Jerry; Kook, John; Moreau-Gobard, Romain; Hsu, Stephen; Ahiekpor-Dravi, Alexis; Crum, Lawrence A.; Eaton, John; Wong, Keith; Sekins, K. Michael

    2012-10-01

    In-vivo focused ultrasound studies were computationally simulated and conducted experimentally with the aim of occluding porcine superficial femoral arteries (SFA) via thermal coagulation. A multi-array HIFU applicator was used which electronically scanned multiple beam foci around the target point. The spatio-temporally averaged acoustic and temperature fields were simulated in a fluid dynamics and acousto-thermal finite element model with representative tissue fields, including muscle, vessel and blood. Simulations showed that with an acoustic power of 200W and a dose time of 60s, perivascular tissue reached 91°C; and yet blood reached a maximum 59°C, below the coagulation objective for this dose regime (75°C). Per simulations, acoustic-streaming induced velocity in blood reached 6.1cm/s. In in-vivo experiments, several arteries were treated. As simulated, thermal lesions were observed in muscle surrounding SFA in all cases. In dosing limited to 30 to 60 seconds, it required 257W to provide occlusion (one complete and one partial occlusion). Angiography and histology showed evidence of thrombogenesis and collagen shrinkage-based vessel constriction at these doses.

  18. A Study on Modeling of Transmission Line in Digital Type Real-Time Power System Simulator

    Science.gov (United States)

    Yasuda, Yuji; Yokoyama, Akihiko; Tada, Yasuyuki

    In modern power systems, it is important to analyze various kindes of dynamic phenomena which appear in the system. When the effectiveness of new power electronics based apparatus, protective relay systems and etc. is tested, a real-time power system simulator is becoming a very effective tool. In general, however, it is very expensive and it is very difficult for beginners to understand how to use it. Therefore, studies on low-cost and easy-use real-time power system simulators have so far been done. We have developed models of power system components for the real-time power system simulator using DSP (Digital Signal Processor) combined with commercial CAD (Computer Aided Design) soft "MATLAB/SIMULINK". The use of commercial softwares can drastically decrease the development cost of the simulator. In this paper, a simplified reduction model of unbalanced three-phase transmission network with mutual impedance is proposed for analysis of various kinds of stability phenomena by use of the digital simulator. The proposed network model is constructed automatically and efficiently even for connection of both current source type models and voltage source type models of power apparatus such as generators, FACTS devices and loads.

  19. [Learning in clinical simulation: observational study on satisfaction perceived by students of nursing].

    Science.gov (United States)

    Rubbi, Ivan; Ferri, Paola; Andreina, Giulia; Cremonini, Valeria

    2016-01-01

    Simulation in the context of the educational workshop is becoming an important learning method, as it allows to play realistic clinical-care situations. These vocational training activities promote the development of cognitive, affective and psychomotor skills in a pedagogical context safe and risk-free, but need to be accounted for using by valid and reliable instruments. To inspect the level of satisfaction of the students of a Degree in Nursing in northern Italy about static and high-fidelity exercises with simulators and clinical cases. A prospective observational study has been conducted involving a non-probabili- stic sample of 51 third-year students throughout the academic year 2013/14. The data collection instrument consists of three questionnaires Student Satisfaction and Self-confidence in Learning Scale, Educational Practices Questionnaire, Simulation Design Scale and 3 questions on overall satisfaction. Statistical analysis was performed with SPSS 20.0 and Office 2003 Excel. The response rate of 89.5% is obtained. The Cronbach Alfa showed a good internal reliability (α = .982). The students were generally satisfied with the activities carried out in the teaching laboratory, showing more enthusiasm for the simulation with static mannequins (71%) and with high-fidelity simulators (60%), activities for which they have experienced a significant involvement and active learning. The teaching with clinical cases scored a lesser degree of satisfaction (38%) and for this method it was found the largest number of elements of weakness.

  20. Biomechanical simulations of the scoliotic deformation process in the pinealectomized chicken: a preliminary study

    Directory of Open Access Journals (Sweden)

    Villemure Isabelle

    2007-11-01

    Full Text Available Abstract Background The basic mechanisms whereby mechanical factors modulate the metabolism of the growing spine remain poorly understood, especially the role of growth adaptation in spinal disorders like in adolescent idiopathic scoliosis (AIS. This paper presents a finite element model (FEM that was developed to simulate early stages of scoliotic deformities progression using a pinealectomized chicken as animal model. Methods The FEM includes basic growth and growth modulation created by the muscle force imbalance. The experimental data were used to adapt a FEM previously developed to simulate the scoliosis deformation process in human. The simulations of the spine deformation process are compared with the results of an experimental study including a group of pinealectomized chickens. Results The comparison of the simulation results of the spine deformation process (Cobb angle of 37° is in agreement with experimental scoliotic deformities of two representative cases (Cobb angle of 41° and 30°. For the vertebral wedging, a good agreement is also observed between the calculated (28° and the observed (25° – 30° values. Conclusion The proposed biomechanical model presents a novel approach to realistically simulate the scoliotic deformation process in pinealectomized chickens and investigate different parameters influencing the progression of scoliosis.

  1. Simulation of GOES-R ABI aerosol radiances using WRF-CMAQ: a case study approach

    Science.gov (United States)

    Christopher, S. A.

    2014-04-01

    In anticipation of the upcoming GOES-R launch we simulate visible and near-infrared reflectances of the Advanced Baseline Imager (ABI) for cases of high aerosol loading containing regional haze and smoke over the eastern United States. The simulations are performed using the Weather Research and Forecasting (WRF), Sparse Matrix Operator Kernel Emissions (SMOKE), and Community Multiscale Air Quality (CMAQ) models. Geostationary, satellite-derived, biomass-burning emissions are also included as an input to CMAQ. Using the CMAQ aerosol concentrations and Mie calculations, radiance is computed from the discrete ordinate atmospheric radiative transfer model. We present detailed methods for deriving aerosol extinction from WRF and CMAQ outputs. Our results show that the model simulations create a realistic set of reflectances in various aerosol scenarios. The simulated reflectances provide distinct spectral features of aerosols which are then compared to data from the Moderate Resolution Imaging Spectroradiometer (MODIS). We also present a simple technique to synthesize green band reflectance (which will not be available on the ABI), using the model-simulated blue and red band reflectance. This study is an example of the use of air quality modeling in improving products and techniques for Earth-observing missions.

  2. Lipopolysaccharide Membranes and Membrane Proteins of Pseudomonas aeruginosa Studied by Computer Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Straatsma, TP

    2006-12-01

    Pseudomonas aeruginosa is a ubiquitous environmental Gram-negative bacterium with high metabolic versatility and an exceptional ability to adapt to a wide range of ecological environments, including soil, marches, coastal habitats, plant and animal tissues. Gram-negative microbes are characterized by the asymmetric lipopolysaccharide outer membrane, the study of which is important for a number of applications. The adhesion to mineral surfaces plays a central role in characterizing their contribution to the fate of contaminants in complex environmental systems by effecting microbial transport through soils, respiration redox chemistry, and ion mobility. Another important application stems from the fact that it is also a major opportunistic human pathogen that can result in life-threatening infections in many immunocompromised patients, such as lung infections in children with cystic fibrosis, bacteraemia in burn victims, urinary-tract infections in catheterized patients, hospital-acquired pneumonia in patients on respirators, infections in cancer patients receiving chemotherapy, and keratitis and corneal ulcers in users of extended-wear soft contact lenses. The inherent resistance against antibiotics which has been linked with the specific interactions in the outer membrane of P. aeruginosa makes these infections difficult to treat. Developments in simulation methodologies as well as computer hardware have enabled the molecular simulation of biological systems of increasing size and with increasing accuracy, providing detail that is difficult or impossible to obtain experimentally. Computer simulation studies contribute to our understanding of the behavior of proteins, protein-protein and protein-DNA complexes. In recent years, a number of research groups have made significant progress in applying these methods to the study of biological membranes. However, these applications have been focused exclusively on lipid bilayer membranes and on membrane proteins in lipid

  3. Simulation studies of the response function of a radioactive waste assay system.

    Science.gov (United States)

    Gurau, Daniela; Sima, Octavian

    2012-01-01

    A simulation program based on GEANT 3.21 toolkit was developed to simulate the response function of ISOCART (Ortec) gamma-ray spectrometry system applied to radioactive waste drum assessment. In view of studying the effects of possible non-homogeneous radioactivity distribution in the drum, the volume of the drum was fictitiously divided into several spatial domains. The simulation program was applied repeatedly considering each time the source distributed in another domain. In this way the expected spectra in the energy range from 50 to 2000keV as well as the full energy peak and the total efficiencies were obtained for the case when the source is distributed in each domain and also for the case when the source is uniformly distributed in the entire drum. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. A study of workstation computational performance for real-time flight simulation

    Science.gov (United States)

    Maddalon, Jeffrey M.; Cleveland, Jeff I., II

    1995-01-01

    With recent advances in microprocessor technology, some have suggested that modern workstations provide enough computational power to properly operate a real-time simulation. This paper presents the results of a computational benchmark, based on actual real-time flight simulation code used at Langley Research Center, which was executed on various workstation-class machines. The benchmark was executed on different machines from several companies including: CONVEX Computer Corporation, Cray Research, Digital Equipment Corporation, Hewlett-Packard, Intel, International Business Machines, Silicon Graphics, and Sun Microsystems. The machines are compared by their execution speed, computational accuracy, and porting effort. The results of this study show that the raw computational power needed for real-time simulation is now offered by workstations.

  5. Feasibility Study for Installing Machine in Production Line to Avoid Particle Contamination Based on CFD Simulation

    Science.gov (United States)

    Khaokom, Adisorn; Thongsri, Jatuporn

    2017-10-01

    Ventilation system inside production line for electronic component production needs to meet the factory standard. Because it can eliminate small particles which may cause of human or machine in production as well as it can distribute the circulating air temperature uniformly. CFD is used in this research in order to study the feasibility and plan for machine layout in production line before actual installation. The simulation shows the airflow in every area inside production line. From simulation with releasing the particles from human and machine is found that this ventilation system generates airflow that makes most particles float out of the machines and no particle downs to the conveyor, it results to contamination. In addition, the simulation also shows the range of 19-26 °C air temperature that meets the factory standard. The results of this research are the parts of the data to renovate the production line to get more efficiency and proper on the production.

  6. 3D source localization derived from subdural strip and grid electrodes: a simulation study.

    Science.gov (United States)

    Dümpelmann, Matthias; Fell, Jürgen; Wellmer, Jörg; Urbach, Horst; Elger, Christian E

    2009-06-01

    Little experience exists in the application of source reconstruction methods to recordings from subdural strip and grid electrodes. This study addressed the question, whether reliable and accurate 3D source localization is possible from the Electrocorticogram (ECoG). The accuracy of source reconstruction was investigated by simulations and a case study. Simulated sources were used to compute potentials at the electrode positions derived from the MRI of a patient with subdural electrodes. Used procedures were the linear estimation (minimum norm) algorithm and the MUSIC (MUltiple SIgnal Classification) scan. Maxima of linear estimation were attracted to adjacent electrodes. Reliable localization with a localization error 15 mm was only achieved for about 35% of the original source positions. Maxima of the MUSIC metric were identical to original positions for simulations without noise. Noise reduced the percentage of reliable solutions down to a 79.0%. Electrode contacts distant to the source had small influence on localization accuracy. The case study supported simulation results. Reliable source reconstruction derived from ECoG can be achieved by the application of the MUSIC algorithm. Linear estimation needs additional compensation mechanisms. MUSIC based 3D localization based on ECoG has the potential improving epilepsy diagnosis and cognitive research.

  7. Designing simulator tools for rail research: the case study of a train driving microworld.

    Science.gov (United States)

    Naweed, A; Hockey, G R J; Clarke, S D

    2013-05-01

    The microworld simulator paradigm is well established in the areas of ship-navigation and spaceflight, but has yet to be applied to rail. This paper presents a case study aiming to address this research gap, and describes the development of a train driving microworld as a tool to overcome some common research barriers. A theoretical framework for microworld design is tested and used to explore some key methodological issues and characteristics of train driving, enhancing theory development and providing a useful guideline for the designers of other collision-avoidance systems. A detailed description is given of the ATREIDES (Adaptive Train Research Enhanced Information Display & Environment Simulator) microworld, which simulates the work environment of a train driver in a high-speed passenger train. General indications of the testable driving scenarios that may be simulated are given, and an example of an ATREIDES-based study is presented to illustrate its applied research potential. The article concludes with a review of the design process, considers some strengths and limitations, and explores some future initiatives towards enhancing the systematic study of rail research in the human factors community. Copyright © 2012 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  8. A Study on Bipedal and Mobile Robot Behavior Through Modeling and Simulation

    Directory of Open Access Journals (Sweden)

    Nirmala Nirmala

    2015-05-01

    Full Text Available The purpose of this work is to study and analyze mobile robot behavior. In performing this, a framework is adopted and developed for mobile and bipedal robot. The robots are design, build, and run as proceed from the development of mechanical structure, electronics and control integration, and control software application. The behavior of those robots are difficult to be observed and analyzed qualitatively. To evaluate the design and behavior quality, modeling and simulation of robot structure and its task capability is performed. The stepwise procedure to robot behavior study is explained. Behavior cases study are experimented to bipedal robots, transporter robot and Autonomous Guided Vehicle (AGV developed at our institution. The experimentation are conducted on those robots by adjusting their dynamic properties and/or surrounding environment. Validation is performed by comparing the simulation result and the real robot execution. The simulation gives a more idealistic behavior execution rather than realistic one. Adjustments are performed to fine tuning simulation's parameters to provide a more realistic performance.

  9. Simulating a base population in honey bee for molecular genetic studies.

    Science.gov (United States)

    Gupta, Pooja; Conrad, Tim; Spötter, Andreas; Reinsch, Norbert; Bienefeld, Kaspar

    2012-06-27

    Over the past years, reports have indicated that honey bee populations are declining and that infestation by an ecto-parasitic mite (Varroa destructor) is one of the main causes. Selective breeding of resistant bees can help to prevent losses due to the parasite, but it requires that a robust breeding program and genetic evaluation are implemented. Genomic selection has emerged as an important tool in animal breeding programs and simulation studies have shown that it yields more accurate breeding value estimates, higher genetic gain and low rates of inbreeding. Since genomic selection relies on marker data, simulations conducted on a genomic dataset are a pre-requisite before selection can be implemented. Although genomic datasets have been simulated in other species undergoing genetic evaluation, simulation of a genomic dataset specific to the honey bee is required since this species has a distinct genetic and reproductive biology. Our software program was aimed at constructing a base population by simulating a random mating honey bee population. A forward-time population simulation approach was applied since it allows modeling of genetic characteristics and reproductive behavior specific to the honey bee. Our software program yielded a genomic dataset for a base population in linkage disequilibrium. In addition, information was obtained on (1) the position of markers on each chromosome, (2) allele frequency, (3) χ(2) statistics for Hardy-Weinberg equilibrium, (4) a sorted list of markers with a minor allele frequency less than or equal to the input value, (5) average r(2) values of linkage disequilibrium between all simulated marker loci pair for all generations and (6) average r2 value of linkage disequilibrium in the last generation for selected markers with the highest minor allele frequency. We developed a software program that takes into account the genetic and reproductive biology specific to the honey bee and that can be used to constitute a genomic

  10. Simulating a base population in honey bee for molecular genetic studies

    Directory of Open Access Journals (Sweden)

    Gupta Pooja

    2012-06-01

    Full Text Available Abstract Background Over the past years, reports have indicated that honey bee populations are declining and that infestation by an ecto-parasitic mite (Varroa destructor is one of the main causes. Selective breeding of resistant bees can help to prevent losses due to the parasite, but it requires that a robust breeding program and genetic evaluation are implemented. Genomic selection has emerged as an important tool in animal breeding programs and simulation studies have shown that it yields more accurate breeding value estimates, higher genetic gain and low rates of inbreeding. Since genomic selection relies on marker data, simulations conducted on a genomic dataset are a pre-requisite before selection can be implemented. Although genomic datasets have been simulated in other species undergoing genetic evaluation, simulation of a genomic dataset specific to the honey bee is required since this species has a distinct genetic and reproductive biology. Our software program was aimed at constructing a base population by simulating a random mating honey bee population. A forward-time population simulation approach was applied since it allows modeling of genetic characteristics and reproductive behavior specific to the honey bee. Results Our software program yielded a genomic dataset for a base population in linkage disequilibrium. In addition, information was obtained on (1 the position of markers on each chromosome, (2 allele frequency, (3 χ2 statistics for Hardy-Weinberg equilibrium, (4 a sorted list of markers with a minor allele frequency less than or equal to the input value, (5 average r2 values of linkage disequilibrium between all simulated marker loci pair for all generations and (6 average r2 value of linkage disequilibrium in the last generation for selected markers with the highest minor allele frequency. Conclusion We developed a software program that takes into account the genetic and reproductive biology specific to the honey bee

  11. Study on the retentivity of the volatile components of simulated guava juice using ultrafiltration

    OpenAIRE

    Saad Hashim Khalil; Mohamed Kheireddine Aroua; Nik Meriam Sulaiman

    2002-01-01

    An experimental investigation on retentivity of major guava juice volatile compounds during ultrafiltration is presented in this paper. Simulated guava juice solutions were used throughout the study and the ultrafiltration was carried out in a batch stirred cell system. Polyethersulfone membranes with MWCO of 100,000 and 500,000 were used. The effects of important process operating parameters such as pressure and pectin concentration were studied. It was found that hydrophobic interactions wi...

  12. Oral Factors Affecting Titanium Elution and Corrosion: An In Vitro Study Using Simulated Body Fluid

    OpenAIRE

    Hideki Suito; Yuki Iwawaki; Takaharu Goto; Yoritoki Tomotake; Tetsuo Ichikawa

    2013-01-01

    OBJECTIVES: Ti, which is biocompatible and resistant to corrosion, is widely used for dental implants, particularly in patients allergic to other materials. However, numerous studies have reported on Ti allergy and the in vitro corrosion of Ti. This study investigated the conditions that promote the elution of Ti ions from Ti implants. METHODS: Specimens of commercially pure Ti, pure nickel, a magnetic alloy, and a gold alloy were tested. Each specimen was immersed in a simulated body fluid (...

  13. Anatomically Detailed and Large-Scale Simulations Studying Synapse Loss and Synchrony Using NeuroBox

    Science.gov (United States)

    Breit, Markus; Stepniewski, Martin; Grein, Stephan; Gottmann, Pascal; Reinhardt, Lukas; Queisser, Gillian

    2016-01-01

    The morphology of neurons and networks plays an important role in processing electrical and biochemical signals. Based on neuronal reconstructions, which are becoming abundantly available through databases such as NeuroMorpho.org, numerical simulations of Hodgkin-Huxley-type equations, coupled to biochemical models, can be performed in order to systematically investigate the influence of cellular morphology and the connectivity pattern in networks on the underlying function. Development in the area of synthetic neural network generation and morphology reconstruction from microscopy data has brought forth the software tool NeuGen. Coupling this morphology data (either from databases, synthetic, or reconstruction) to the simulation platform UG 4 (which harbors a neuroscientific portfolio) and VRL-Studio, has brought forth the extendible toolbox NeuroBox. NeuroBox allows users to perform numerical simulations on hybrid-dimensional morphology representations. The code basis is designed in a modular way, such that e.g., new channel or synapse types can be added to the library. Workflows can be specified through scripts or through the VRL-Studio graphical workflow representation. Third-party tools, such as ImageJ, can be added to NeuroBox workflows. In this paper, NeuroBox is used to study the electrical and biochemical effects of synapse loss vs. synchrony in neurons, to investigate large morphology data sets within detailed biophysical simulations, and used to demonstrate the capability of utilizing high-performance computing infrastructure for large scale network simulations. Using new synapse distribution methods and Finite Volume based numerical solvers for compartment-type models, our results demonstrate how an increase in synaptic synchronization can compensate synapse loss at the electrical and calcium level, and how detailed neuronal morphology can be integrated in large-scale network simulations. PMID:26903818

  14. Anatomically detailed and large-scale simulations studying synapse loss and synchrony using NeuroBox

    Directory of Open Access Journals (Sweden)

    Markus eBreit

    2016-02-01

    Full Text Available The morphology of neurons and networks plays an important role in processing electrical and biochemical signals. Based on neuronal reconstructions, which are becoming abundantly available through databases such as NeuroMorpho.org, numerical simulations of Hodgkin-Huxley-type equations, coupled to biochemical models, can be performed in order to systematically investigate the influence of cellular morphology and the connectivity pattern in networks on the underlying function. Development in the area of synthetic neural network generation and morphology reconstruction from microscopy data has brought forth the software tool NeuGen. Coupling this morphology data (either from databases, synthetic or reconstruction to the simulation platform UG 4 (which harbors a neuroscientific portfolio and VRL-Studio, has brought forth the extendible toolbox NeuroBox. NeuroBox allows users to perform numerical simulations on hybrid-dimensional morphology representations. The code basis is designed in a modular way, such that e.g. new channel or synapse types can be added to the library. Workflows can be specified through scripts or through the VRL-Studio graphical workflow representation. Third-party tools, such as ImageJ, can be added to NeuroBox workflows. In this paper, NeuroBox is used to study the electrical and biochemical effects of synapse loss vs. synchrony in neurons, to investigate large morphology data sets within detailed biophysical simulations, and used to demonstrate the capability of utilizing high-performance computing infrastructure for large scale network simulations. Using new synapse distribution methods and Finite Volume based numerical solvers for compartment-type models, our results demonstrate how an increase in synaptic synchronization can compensate synapse loss at the electrical and calcium level, and how detailed neuronal morphology can be integrated in large-scale network simulations.

  15. Angular momentum evolution in dark matter haloes: a study of the Bolshoi and Millennium simulations

    Science.gov (United States)

    Contreras, S.; Padilla, N.; Lagos, C. D. P.

    2017-12-01

    We use three different cosmological dark matter simulations to study how the orientation of the angular momentum (AM) vector in dark matter haloes evolve with time. We find that haloes in this kind of simulations are constantly affected by a spurious change of mass, which translates into an artificial change in the orientation of the AM. After removing the haloes affected by artificial mass change, we found that the change in the orientation of the AM vector is correlated with time. The change in its angle and direction (I.e. the angle subtended by the AM vector in two consecutive time-steps) that affect the AM vector has a dependence on the change of mass that affects a halo, the time elapsed in which the change of mass occurs and the halo mass. We create a Monte Carlo simulation that reproduces the change of angle and direction of the AM vector. We reproduce the angular separation of the AM vector since a lookback time of 8.5 Gyr to today (α) with an accuracy of approximately 0.05 in cos(α). We are releasing this Monte Carlo simulation together with this publication. We also create a Monte Carlo simulation that reproduces the change of the AM modulus. We find that haloes in denser environments display the most dramatic evolution in their AM direction, as well as haloes with a lower specific AM modulus. These relations could be used to improve the way we follow the AM vector in low-resolution simulations.

  16. Blinded randomized controlled study of a web-based otoscopy simulator in undergraduate medical education.

    Science.gov (United States)

    Stepniak, Camilla; Wickens, Brandon; Husein, Murad; Paradis, Josee; Ladak, Hanif M; Fung, Kevin; Agrawal, Sumit K

    2017-06-01

    OtoTrain is a Web-based otoscopy simulator that has previously been shown to have face and content validity. The objective of this study was to evaluate the effectiveness of this Web-based otoscopy simulator in teaching diagnostic otoscopy to novice learners STUDY DESIGN: Prospective, blinded randomized control trial. Second-year medical students were invited to participate in the study. A pretest consisted of a series of otoscopy videos followed by an open-answer format assessment pertaining to the characteristics and diagnosis of each video. Participants were then randomly divided into a control group and a simulator group. Following the pretest, both groups attended standard otology lectures, but the simulator group was additionally given unlimited access to OtoTrain for 1 week. A post-test was completed using a separate set of otoscopy videos. Tests were graded based on a comprehensive marking scheme. The pretest and post-test were anonymized, and the three evaluators were blinded to student allotment. A total of 41 medical students were enrolled in the study and randomized to the control group (n = 20) and the simulator group (n = 21). There was no significant difference between the two groups on their pretest scores. With the standard otology lectures, the control group had a 31% improvement in their post-test score (mean ± standard error of the mean, 30.4 ± 1.5) compared with their pretest score (23.3 ± 1.8) (P simulator group had the addition of OtoTrain to the otology lectures, and their score improved by 71% on their post-test (37.8 ± 1.6) compared to their pretest (22.1 ± 1.9) (P simulator group had a 24% higher score than the control group (P < .002). Inter-rater reliability between the blinded evaluators was excellent (r = 0.953, P < .001). The use of OtoTrain increased the diagnostic otoscopic performance in novice learners. OtoTrain may be an effective teaching adjunct for undergraduate medical students. 1b. Laryngoscope, 127:1306-1311, 2017.

  17. Simulating large-scale pedestrian movement using CA and event driven model: Methodology and case study

    Science.gov (United States)

    Li, Jun; Fu, Siyao; He, Haibo; Jia, Hongfei; Li, Yanzhong; Guo, Yi

    2015-11-01

    Large-scale regional evacuation is an important part of national security emergency response plan. Large commercial shopping area, as the typical service system, its emergency evacuation is one of the hot research topics. A systematic methodology based on Cellular Automata with the Dynamic Floor Field and event driven model has been proposed, and the methodology has been examined within context of a case study involving the evacuation within a commercial shopping mall. Pedestrians walking is based on Cellular Automata and event driven model. In this paper, the event driven model is adopted to simulate the pedestrian movement patterns, the simulation process is divided into normal situation and emergency evacuation. The model is composed of four layers: environment layer, customer layer, clerk layer and trajectory layer. For the simulation of movement route of pedestrians, the model takes into account purchase intention of customers and density of pedestrians. Based on evacuation model of Cellular Automata with Dynamic Floor Field and event driven model, we can reflect behavior characteristics of customers and clerks at the situations of normal and emergency evacuation. The distribution of individual evacuation time as a function of initial positions and the dynamics of the evacuation process is studied. Our results indicate that the evacuation model using the combination of Cellular Automata with Dynamic Floor Field and event driven scheduling can be used to simulate the evacuation of pedestrian flows in indoor areas with complicated surroundings and to investigate the layout of shopping mall.

  18. Simulation and experimental study on distortion of butt and T-joints using WELD PLANNER

    Energy Technology Data Exchange (ETDEWEB)

    Sulaiman, Mohd Shahar; Manurung, Yupiter HP; Rahim, Mohammad Ridzwan Abdul Mohd; Redza, Ridhwan; Lidam, Robert Ngendang Ak.; Abas, Sunhaji Kiyai; Tham, Ghalib [Universiti Teknologi MARA, Kuala Lumpur (Malaysia); Haruman, Esa [Bakrie University, Jakarta (Indonesia); Chau, Chan Yin [ESI Group, Kuala Lumpur (Malaysia)

    2011-10-15

    This paper investigates the capability of linear thermal elastic numerical analysis to predict the welding distortion that occurs due to GMAW process. Distortion is considered as the major stumbling block that can adversely affect the dimensional accuracy and thus lead to expensive corrective work. Hence, forecast of distortion is crucially needed and ought to be determined in advance in order to minimize the negative effects, improve the quality of welded parts and finally to reduce the production costs. In this study, the welding deformation was simulated by using relatively new FEM software WELD PLANNER developed by ESI Group. This novel Welding Simulation Solution was employed to predict welding distortion induced in butt and T-joints with thickness of 4 mm. Low carbon steel material was used for the simulation and experimental study. A series of experiments using fully automated welding process were conducted for verification purpose to measure the distortion. By comparing between the simulation and experimental results, it was found out that this program code offered fast solution analysis time in estimating weld induced distortion within acceptable accuracy.

  19. A comparative study on real lab and simulation lab in communication engineering from students' perspectives

    Science.gov (United States)

    Balakrishnan, B.; Woods, P. C.

    2013-05-01

    Over the years, rapid development in computer technology has engendered simulation-based laboratory (lab) in addition to the traditional hands-on (physical) lab. Many higher education institutions adopt simulation lab, replacing some existing physical lab experiments. The creation of new systems for conducting engineering lab activities has raised concerns among educators on the merits and shortcomings of both physical and simulation labs; at the same time, many arguments have been raised on the differences of both labs. Investigating the effectiveness of both labs is complicated, as there are multiple factors that should be considered. In view of this challenge, a study on students' perspectives on their experience related to key aspects on engineering laboratory exercise was conducted. In this study, the Visual Auditory Read and Kinetic model was utilised to measure the students' cognitive styles. The investigation was done through a survey among participants from Multimedia University, Malaysia. The findings revealed that there are significant differences for most of the aspects in physical and simulation labs.

  20. Study of Structure and Deformation Pathways in Ti-7Al Using Atomistic Simulations, Experiments, and Characterization

    Science.gov (United States)

    Venkataraman, Ajey; Shade, Paul A.; Adebisi, R.; Sathish, S.; Pilchak, Adam L.; Viswanathan, G. Babu; Brandes, Matt C.; Mills, Michael J.; Sangid, Michael D.

    2017-05-01

    Ti-7Al is a good model material for mimicking the α phase response of near- α and α+ β phases of many widely used titanium-based engineering alloys, including Ti-6Al-4V. In this study, three model structures of Ti-7Al are investigated using atomistic simulations by varying the Ti and Al atom positions within the crystalline lattice. These atomic arrangements are based on transmission electron microscopy observations of short-range order. The elastic constants of the three model structures considered are calculated using molecular dynamics simulations. Resonant ultrasound spectroscopy experiments are conducted to obtain the elastic constants at room temperature and a good agreement is found between the simulation and experimental results, providing confidence that the model structures are reasonable. Additionally, energy barriers for crystalline slip are established for these structures by means of calculating the γ-surfaces for different slip systems. Finally, the positions of Al atoms in regards to solid solution strengthening are studied using density functional theory simulations, which demonstrate a higher energy barrier for slip when the Al solute atom is closer to (or at) the fault plane. These results provide quantitative insights into the deformation mechanisms of this alloy.

  1. Developing a Canadian Curriculum for Simulation-Based Education in Obstetrics and Gynaecology: A Delphi Study.

    Science.gov (United States)

    Craig, Catherine; Posner, Glenn D

    2017-09-01

    As obstetrics and gynaecology (Ob/Gyn) residency training programs move towards a competence-based approach to training and assessment, the development of a national standardized simulation curriculum is essential. The primary goal of this study was to define the fundamental content for the Canadian Obstetrics and Gynecology Simulation curriculum. A modified Delphi technique was used to achieve consensus in three rounds by surveying residency program directors or their local simulation educator delegates in 16 accredited Canadian Ob/Gyn residency programs. A consensus rate of 80% was agreed upon. Survey results were collected over 11 months in 2016. Response rates for the Delphi were 50% for the first round, 81% for the second round, and 94% for the third round. The first survey resulted in 84 suggested topics. These were organized into four categories: obstetrics high acuity low frequency events, obstetrics common events, gynaecology high acuity low frequency events, and gynaecology common events. Using the modified Delphi method, consensus was reached on 6 scenarios. This study identified the content for a national simulation-based curriculum for Ob/Gyn residency training programs and is the first step in the development of this curriculum. Copyright © 2017 The Society of Obstetricians and Gynaecologists of Canada/La Société des obstétriciens et gynécologues du Canada. Published by Elsevier Inc. All rights reserved.

  2. Benchmark Study of 3D Pore-scale Flow and Solute Transport Simulation Methods

    Science.gov (United States)

    Scheibe, T. D.; Yang, X.; Mehmani, Y.; Perkins, W. A.; Pasquali, A.; Schoenherr, M.; Kim, K.; Perego, M.; Parks, M. L.; Trask, N.; Balhoff, M.; Richmond, M. C.; Geier, M.; Krafczyk, M.; Luo, L. S.; Tartakovsky, A. M.

    2015-12-01

    Multiple numerical approaches have been developed to simulate porous media fluid flow and solute transport at the pore scale. These include 1) methods that explicitly model the three-dimensional geometry of pore spaces and 2) methods that conceptualize the pore space as a topologically consistent set of stylized pore bodies and pore throats. In previous work we validated a model of the first type, using computational fluid dynamics (CFD) codes employing standard finite volume method (FVM), against magnetic resonance velocimetry (MRV) measurements of pore-scale velocities. Here we expand that benchmark study to include additional models of the first type based on the immersed-boundary method (IMB), lattice Boltzmann method (LBM), and smoothed particle hydrodynamics (SPH), as well as a model of the second type, a pore-network model (PNM). While the PNM approach is computationally much less demanding than direct numerical simulation methods, the effect of conceptualizing complex three-dimensional pore geometries in the manner of PNMs has not been fully determined. We apply all five approaches (FVM-based CFD, IMB, LBM, SPH and PNM) to simulate pore-scale velocity distributions and nonreactive solute transport, and intercompare the model results. Comparisons are drawn both in terms of macroscopic variables (e.g., permeability, solute breakthrough curves) and microscopic variables (e.g., local velocities and concentrations). Generally good agreement was achieved among the various approaches, but some differences were observed depending on the model context. The benchmark study was challenging because of variable capabilities of the codes, and inspired some code enhancements to allow consistent comparison of flow and transport simulations across the full suite of methods. This study provides support for confidence in a variety of pore-scale modeling methods, and motivates further development and application of pore-scale simulation methods.

  3. A cross-national study to objectively evaluate the quality of diverse simulation approaches for undergraduate nursing students.

    Science.gov (United States)

    Kable, Ashley K; Levett-Jones, Tracy L; Arthur, Carol; Reid-Searl, Kerry; Humphreys, Melanie; Morris, Sara; Walsh, Pauline; Witton, Nicola J

    2017-10-12

    The aim of this paper is to report the results of a cross-national study that evaluated a range of simulation sessions using an observation schedule developed from evidence-based quality indicators. Observational data were collected from 17 simulation sessions conducted for undergraduate nursing students at three universities in Australia and the United Kingdom. The observation schedule contained 27 questions that rated simulation quality. Data were collected by direct observation and from video recordings of the simulation sessions. Results indicated that the highest quality scores were for provision of learning objectives prior to the simulation session (90%) and debriefing (72%). Student preparatiosn and orientation (67%) and perceived realism and fidelity (67%) were scored lower than other components of the simulation sessions. This observational study proved to be an effective strategy to identify areas of strength and those needing further development to improve simulation sessions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Assessment and management of serotonin syndrome in a simulated patient study of Australian community pharmacies

    Directory of Open Access Journals (Sweden)

    MacFarlane B

    2016-06-01

    Full Text Available Background: The incidence of serotonin syndrome is increasing due to the widening use of serotonergic drugs. Identification of serotonin syndrome is challenging as the manifestations are diverse. Misdiagnosis can lead to delay in care and inappropriate treatment. Objectives: The objectives of this study were to determine if staff of community pharmacies in Australia could identify the symptoms of serotonin syndrome in simulated patients and recommend an appropriate course of action. Methods: Agents acting on behalf of a simulated patient were trained on a patient scenario that reflected possible serotonin syndrome due to an interaction between duloxetine and recently prescribed tramadol. They entered 148 community pharmacies in Australia to ask for advice about a 60 year old male simulated patient who was ‘not feeling well’. The interaction was audio recorded and analysed for degree of access to the pharmacist, information gathered by pharmacy staff, management advice given and pharmacotherapy recommended. Results: The simulated patient’s agent was consulted by a pharmacist in 94.0% (139/148 of cases. The potential for serotonin syndrome was identified by 35.1% (52/148 of pharmacies. Other suggested causes of the simulated patient’s symptoms were viral (16.9%; 25/148 and cardiac (15.5%; 23/148. A total of 33.8% (50/148 of pharmacies recommended that the simulated patient should cease taking tramadol. This advice always came from the pharmacist. Immediate cessation of tramadol was advised by 94.2% (49/52 of pharmacists correctly identifying serotonin syndrome. The simulated patient was advised to seek urgent medical care in 14.2% (21/148 of cases and follow up with a doctor when possible in 68.2% (101/148 of cases. The majority of pharmacies (87.8%; 130/148 did not recommend non-prescription medicines. Conclusion: While not identifying the cause of the simulated patient’s symptoms in the majority of cases, community pharmacies

  5. Assessment and management of serotonin syndrome in a simulated patient study of Australian community pharmacies.

    Science.gov (United States)

    Macfarlane, Brett; Bergin, Jenny; Peterson, Gregory M

    2016-01-01

    The incidence of serotonin syndrome is increasing due to the widening use of serotonergic drugs. Identification of serotonin syndrome is challenging as the manifestations are diverse. Misdiagnosis can lead to delay in care and inappropriate treatment. The objectives of this study were to determine if staff of community pharmacies in Australia could identify the symptoms of serotonin syndrome in simulated patients and recommend an appropriate course of action. Agents acting on behalf of a simulated patient were trained on a patient scenario that reflected possible serotonin syndrome due to an interaction between duloxetine and recently prescribed tramadol. They entered 148 community pharmacies in Australia to ask for advice about a 60 year old male simulated patient who was 'not feeling well'. The interaction was audio recorded and analysed for degree of access to the pharmacist, information gathered by pharmacy staff, management advice given and pharmacotherapy recommended. The simulated patient's agent was consulted by a pharmacist in 94.0% (139/148) of cases. The potential for serotonin syndrome was identified by 35.1% (52/148) of pharmacies. Other suggested causes of the simulated patient's symptoms were viral (16.9%; 25/148) and cardiac (15.5%; 23/148). A total of 33.8% (50/148) of pharmacies recommended that the simulated patient should cease taking tramadol. This advice always came from the pharmacist. Immediate cessation of tramadol was advised by 94.2% (49/52) of pharmacists correctly identifying serotonin syndrome. The simulated patient was advised to seek urgent medical care in 14.2% (21/148) of cases and follow up with a doctor when possible in 68.2% (101/148) of cases. The majority of pharmacies (87.8%; 130/148) did not recommend non-prescription medicines. While not identifying the cause of the simulated patient's symptoms in the majority of cases, community pharmacies recommended appropriate action to minimise the health impact of serotonin syndrome

  6. SIMULATION STUDY OF LONGITUDINAL FORCES IN THE COUPLING DEVICE OF HEAVY FREIGHT TRAINS

    Directory of Open Access Journals (Sweden)

    Józef Stokłosa

    2014-03-01

    Full Text Available On the LHS line (Broad-gauge Metallurgical Line, far out West of the railway line with a gauge of 1520 mm, heavy goods trains for a gross weight 5500 tons and a length of 850 m are operated. The article presents the results of a simulation study of the forces that occur in the automatic coupling device of SA-3 type of Russian production train consisting of 60 coal wagons of Russian construction of gross mass 91 tons each. The train moves on the 1520 mm gauge tracks curve S type (the radius of curvature of curves 300 m. Simulation studies were conducted using the Train Module of program to dynamic study multi-elements systems of Universal Mechanism UM 6.0.

  7. Five-Phase Modular External Rotor PM Machines with Different Rotor Poles: A Comparative Simulation Study

    Directory of Open Access Journals (Sweden)

    A. S. Abdel-Khalik

    2012-01-01

    Full Text Available The performance of fault-tolerant modular permanent magnet machines depends on the proper selection of the pole and slot numbers which result in negligible coupling between phases. The preferred slot and pole number combinations eliminate the effect of low-order harmonics in the stator magnetomotive force and thereby the vibration and stray loss are reduced. In this paper, three external rotor machines with identical machine dimensions are designed with different slots per phase per pole ratios. A simulation study is carried out using finite element analysis to compare the performance of the three machines in terms of machine torque density, ripple torque, core loss, and machine efficiency. A mathematical model based on the conventional-phase-model approach is also used for the comparative study. The simulation study is extended to depict machine performance under fault conditions.

  8. Bayesian Modeling for Genetic Anticipation in Presence of Mutational Heterogeneity: A Case Study in Lynch Syndrome

    DEFF Research Database (Denmark)

    Boonstra, Philip S; Mukherjee, Bhramar; Taylor, Jeremy M G

    2011-01-01

    Summary Genetic anticipation, described by earlier age of onset (AOO) and more aggressive symptoms in successive generations, is a phenomenon noted in certain hereditary diseases. Its extent may vary between families and/or between mutation subtypes known to be associated with the disease phenoty...

  9. Normal linear models with genetically structured residual variance heterogeneity: a case study

    DEFF Research Database (Denmark)

    Sorensen, Daniel; Waagepetersen, Rasmus Plenge

    2003-01-01

    Normal mixed models with different levels of heterogeneity in the residual variance are fitted to pig litter size data. Exploratory analysis and model assessment is based on examination of various posterior predictive distributions. Comparisons based on Bayes factors and related criteria favour...... models with a genetically structured residual variance heterogeneity. There is, moreover, strong evidence of a negative correlation between the additive genetic values affecting litter size and those affecting residual variance. The models are also compared according to the purposes for which they might...... be used, such as prediction of 'future' data, inference about response to selection and ranking candidates for selection. A brief discussion is given of some implications for selection of the genetically structured residual variance model....

  10. The study on modelled and measured weather data for building energy simulation programs for Malaysia

    Science.gov (United States)

    >B Faizal,

    2013-06-01

    This paper will study the usability of future weather data generated from climate model for Malaysia. Detailed future weather data is required for the building energy assessment as input parameters. The future weather data required is normally achieved from climate prediction models. The purpose of this study is to examine the gaps between weather data generated by climate model and the data measured by weather station in Bayan Lepas, Penang. Furthermore, this studies also to establish the modelled weather data for the use for future building energy simulation program. In order to achieve this purpose, simulated weather data sets HadCM3 were supplied by the Hadley Centre in the UK. The measured weather data was supplied by Malaysian Meteorological Department for Bayan Lepas, Penang. The period of analysed time was 18 years from 1990 to 2007 where the available data overlaps between HadCM3 and measured data. Several major weather variables were used in these studies such as Dry-bulb temperature, Solar radiation and Wind speed. The outcome from this studies shows a good match between HadCM3 data and measured data indicates that HadCM3 model is suitable for the purpose of future building energy simulation for Malaysia.

  11. Studies of the Suitability of Fowlpox as a Decontamination and Thermal Stability Simulant for Variola Major

    Directory of Open Access Journals (Sweden)

    Amanda E. Chambers

    2009-01-01

    Full Text Available Variola major, the causative agent of smallpox, has been eradicated from nature. However, stocks still exist; thus, there is a need for relevant decontamination studies, preferably with nonpathogenic simulants. Previous studies have shown a similarity in response of vaccinia virus and variola major to various decontaminants and thermal inactivation. This study compared vaccinia and fowlpox viruses under similar conditions, using disinfectants and temperatures for which variola major data already existed. Most disinfectants showed similar efficacy against vaccinia and fowlpox, suggesting the utility of fowlpox as a decontamination simulant. Inactivation kinetics studies showed that fowlpox behaved similarly to variola major when treated with 0.1% iodine and 5.7% polyethyleneglycol nonylphenyl ether, 0.025% sodium hypochlorite, 0.05% sodium hypochlorite, and 0.1% cetyltrimethylammonium chloride and 0.05% benzalkonium chloride, but differed in its response to 0.05% iodine and 0.3% polyethyleneglycol nonylphenyl ether and 40% ethanol. Thermal inactivation studies demonstrated that fowlpox is a suitable thermal simulant for variola major between 40∘C and 55∘C.

  12. Heat transition during magnetic heating treatment: Study with tissue models and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Henrich, Franziska [Technische Universität Dresden, Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, 01062 Dresden (Germany); Max Planck Institute for Polymer Research, Physics at Interfaces, 55128 Mainz (Germany); Rahn, Helene, E-mail: helene.rahn@tu-dresden.de [Technische Universität Dresden, Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, 01062 Dresden (Germany); Odenbach, Stefan [Technische Universität Dresden, Institute of Fluid Mechanics, Chair of Magnetofluiddynamics, 01062 Dresden (Germany)

    2015-04-15

    The magnetic heating treatment (MHT) is well known as a promising therapy for cancer diseases. Depending on concentration and specific heating power of the magnetic material as well as on parameters of the magnetic field, temperatures between 43 and 55 °C can be reached. This paper deals with the evaluation of heat distribution around such a heat source in a tissue model, thereby focusing on the heat transfer from tissue enriched with magnetic nanoparticles to regions of no or little enrichment of magnetic nanoparticles. We examined the temperature distribution with several tissue phantoms made of polyurethane (PUR) with similar thermal conductivity coefficient as biological tissue. These phantoms are composed of a cylinder with one sphere embedded, enriched with magnetic fluid. Thereby the spheres have different diameters in order to study the influence of the surface-to-volume ratio. The phantoms were exposed to an alternating magnetic field. The magnetically induced heat increase within the phantoms was measured with thermocouples. Those were placed at defined positions inside the phantoms. Based on the measured results a 3-dimensional simulation of each phantom was built. We achieved an agreement between the measured and simulated temperatures for all phantoms produced in this experimental study. The established experiment theoretically allows a prediction of temperature profiles in tumors and the surrounding tissue for the potential cancer treatment and therefore an optimization of e.g. the respective magnetic nanoparticles concentrations for the desirable rise of temperature. - Highlights: • Four phantoms built to measure the temperature distribution during magnetic heating. • Simulations have been carried out based on experimental data. • Measured and simulated temperature distribution for different magnetic field strength. • Temperature profiles for with ferrofluid enriched areas of different size. • Comparison of experimental and simulated data.

  13. A simulation study with a new residual ionospheric error model for GPS radio occultation climatologies

    Directory of Open Access Journals (Sweden)

    J. Danzer

    2015-08-01

    Full Text Available In this study, a new model was explored which corrects for higher order ionospheric residuals in Global Positioning System (GPS radio occultation (RO data. Recently, the theoretical basis of this new "residual ionospheric error model" has been outlined (Healy and Culverwell, 2015. The method was tested in simulations with a one-dimensional model ionosphere. The proposed new model for computing the residual ionospheric error is the product of two factors, one of which expresses its variation from profile to profile and from time to time in terms of measurable quantities (the L1 and L2 bending angles, while the other describes the weak variation with altitude. A simple integral expression for the residual error (Vorob’ev and Krasil’nikova, 1994 has been shown to be in excellent numerical agreement with the exact value, for a simple Chapman layer ionosphere. In this case, the "altitudinal" element of the residual error varies (decreases by no more than about 25 % between ~10 and ~100 km for physically reasonable Chapman layer parameters. For other simple model ionospheres the integral can be evaluated exactly, and results are in reasonable agreement with those of an equivalent Chapman layer. In this follow-up study the overall objective was to explore the validity of the new residual ionospheric error model for more detailed simulations, based on modeling through a complex three-dimensional ionosphere. The simulation study was set up, simulating day and night GPS RO profiles for the period of a solar cycle with and without an ionosphere. The residual ionospheric error was studied, the new error model was tested, and temporal and spatial variations of the model were investigated. The model performed well in the simulation study, capturing the temporal variability of the ionospheric residual. Although it was not possible, due to high noise of the simulated bending-angle profiles at mid- to high latitudes, to perform a thorough latitudinal

  14. Insights into pharmaceutical nanocrystal dissolution: a molecular dynamics simulation study on aspirin.

    Science.gov (United States)

    Greiner, Maximilian; Elts, Ekaterina; Briesen, Heiko

    2014-09-02

    The presented molecular dynamics simulations are the first simulations to reveal dynamic dissolution of a pharmaceutical crystal in its experimentally determined shape. Continuous dissolution at constant undersaturation of the surrounding medium is ensured by introducing a plane of sticky dummy atoms into the water slab. These atoms have a strong interaction potential with dissolved aspirin molecules, but interactions with water are excluded from the calculations. Thus, the number of aspirin molecules diffusing freely in solution is kept at a low value and continuous dissolution of the aspirin crystal is monitored. Further insight into face-specific dissolution is drawn. The dissolution mechanism of receding edges is found for the (001) plane. These findings are in good agreement with experimental results. While the proposed dissolution mechanism for the (100) plane is terrace sinking on a rough surface, no pronounced dissolution of the perfectly flat face is seen in the present work. Molecular simulations of pharmaceuticals in their experimentally obtained structure therefore have shown to be especially suited for the investigation of dissolving faces, where the edges have a pronounced effect. In contrast to previous studies a propagation of the dissolution front into the crystal face is reported, and the crystal bulk is stable over the whole simulation time of 150 ns.

  15. Aeroacoustic Simulations of a Nose Landing Gear with FUN3D: A Grid Refinement Study

    Science.gov (United States)

    Vatsa, Veer N.; Khorrami, Mehdi R.; Lockard, David P.

    2017-01-01

    A systematic grid refinement study is presented for numerical simulations of a partially-dressed, cavity-closed (PDCC) nose landing gear configuration that was tested in the University of Florida's open-jet acoustic facility known as the UFAFF. The unstructured-grid flow solver FUN3D is used to compute the unsteady flow field for this configuration. Mixed-element grids generated using the Pointwise (Registered Trademark) grid generation software are used for numerical simulations. Particular care is taken to ensure quality cells and proper resolution in critical areas of interest in an effort to minimize errors introduced by numerical artifacts. A set of grids was generated in this manner to create a family of uniformly refined grids. The finest grid was then modified to coarsen the wall-normal spacing to create a grid suitable for the wall-function implementation in FUN3D code. A hybrid Reynolds-averaged Navier-Stokes/large eddy simulation (RANS/LES) turbulence modeling approach is used for these simulations. Time-averaged and instantaneous solutions obtained on these grids are compared with the measured data. These CFD solutions are used as input to a FfowcsWilliams-Hawkings (FW-H) noise propagation code to compute the farfield noise levels. The agreement of the computed results with the experimental data improves as the grid is refined.

  16. A simulation study of detection of weapon of mass destruction based on radar

    Science.gov (United States)

    Sharifahmadian, E.; Choi, Y.; Latifi, S.

    2013-05-01

    Typical systems used for detection of Weapon of Mass Destruction (WMD) are based on sensing objects using gamma rays or neutrons. Nonetheless, depending on environmental conditions, current methods for detecting fissile materials have limited distance of effectiveness. Moreover, radiation related to gamma- rays can be easily shielded. Here, detecting concealed WMD from a distance is simulated and studied based on radar, especially WideBand (WB) technology. The WB-based method capitalizes on the fact that electromagnetic waves penetrate through different materials at different rates. While low-frequency waves can pass through objects more easily, high-frequency waves have a higher rate of absorption by objects, making the object recognition easier. Measuring the penetration depth allows one to identify the sensed material. During simulation, radar waves and propagation area including free space, and objects in the scene are modeled. In fact, each material is modeled as a layer with a certain thickness. At start of simulation, a modeled radar wave is radiated toward the layers. At the receiver side, based on the received signals from every layer, each layer can be identified. When an electromagnetic wave passes through an object, the wave's power will be subject to a certain level of attenuation depending of the object's characteristics. Simulation is performed using radar signals with different frequencies (ranges MHz-GHz) and powers to identify different layers.

  17. A Study on a Solar Simulator for Dye Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Kyoung-Jun Lee

    2012-01-01

    Full Text Available Dye-sensitized solar cells (DSSC are emerging low-cost, simple alternatives to conventional solar cells. While there has been considerable study on improving the efficiency of DSSCs, there has not been sufficient research on a photovoltaic power conditioning system adaptable to DSSCs or on a solar simulator for DSSCs. When DSSCs are commercialized in the near future, the DSSC modules must be connected to an adaptable power conditioning system in order to manage the energy produced and provide a suitable interface to the load. In the process of developing a power conditioning system, a solar simulator with the characteristics of DSSCs is essential to show the performance of the maximum power point tracking. In this paper, a virtual DSSC is designed and simulated in PSIM. Irradiation factors, temperature and shadow effects are considered in dynamic link library block in PSIM which is linked to the external C routine. A 100 W converter is built to show the performance of a DSSC as the solar simulator controlled by a digital signal processor.

  18. Google Glass Video Capture of Cardiopulmonary Resuscitation Events: A Pilot Simulation Study.

    Science.gov (United States)

    Kassutto, Stacey M; Kayser, Joshua B; Kerlin, Meeta P; Upton, Mark; Lipschik, Gregg; Epstein, Andrew J; Dine, C Jessica; Schweickert, William

    2017-12-01

    Video recording of resuscitation from fixed camera locations has been used to assess adherence to guidelines and provide feedback on performance. However, inpatient cardiac arrests often happen in unpredictable locations and crowded rooms, making video recording of these events problematic. We sought to understand the feasibility of Google Glass (GG) as a method for recording inpatient cardiac arrests and capturing salient resuscitation factors for post-event review. This observational study involved recording simulated cardiac arrest events on inpatient medical wards. Each simulation was reviewed by 3 methods: in-room physician direct observation, stationary video camera (SVC), and GG. Nurse and physician specialists analyzed the videos for global visibility and audibility, as well as recording quality of predefined resuscitation events and behaviors. Resident code leaders were surveyed regarding attitudes toward GG use in the clinical emergency setting. Of 11 simulated cardiac arrest events, 9 were successfully recorded by all observation methods (1 GG failure, 1 SVC failure). GG was judged slightly better than SVC recording for average global visualization (3.95 versus 3.15, P = .0003) and average global audibility (4.77 versus 4.42, P = .002). Of the GG videos, 19% had limitations in overall interpretability compared with 35% of SVC recordings (P = .039). All 10 survey respondents agreed that GG was easy to use; however, 2 found it distracting and 3 were uncomfortable with future use during actual resuscitations. GG is a feasible and acceptable method for capturing simulated resuscitation events in the inpatient setting.

  19. A simulation study on the focal plane detector of the LAUE project

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, M., E-mail: mkhalil@in2p3.fr [APC Laboratory, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France); Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44100 Ferrara (Italy); Frontera, F. [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44100 Ferrara (Italy); INAF/IASF-Bologna, Via P. Gobetti 101, Bologna (Italy); Caroli, E. [INAF/IASF-Bologna, Via P. Gobetti 101, Bologna (Italy); Virgilli, E.; Valsan, V. [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1, 44100 Ferrara (Italy)

    2015-06-21

    The LAUE project, supported by the Italian Space Agency (ASI), is devoted to the development of a long focal length (even 20 m or longer) Laue lens for gamma ray astronomy between 80 and 600 keV. These lenses take advantage of Bragg diffraction to focus radiation onto a small spot drastically improving the signal to noise ratio as well as reducing the required size of the detector significantly. In this paper we present a Monte-Carlo simulation study with MEGALIB to optimize, for space applications, the detector size to achieve high detection efficiency, and to optimize the position resolution of the detector to reconstruct the Point Spread Function of the lens considered for the LAUE project. Then we will show simulations, using the SILVACO semiconductor simulation toolkit, on the optimized detector to estimate its capacitance per channel and depletion voltage. In all of the simulations, two materials were compared; a low density material (Silicon) and a high density material (Germanium). - Highlights: • The quantized Hall plateaus and Shubnikov de Haas oscillations in transition metal doped topological insulators are observed. • The evidence of a two-dimensional/layered transport of the bulk electrons is reported. • An obvious ferromagnetism in doped topological insulators is observed. • Care should be taken to pindown the transport of the topological SS in topological insulators.

  20. The proton therapy nozzles at Samsung Medical Center: A Monte Carlo simulation study using TOPAS

    Science.gov (United States)

    Chung, Kwangzoo; Kim, Jinsung; Kim, Dae-Hyun; Ahn, Sunghwan; Han, Youngyih

    2015-07-01

    To expedite the commissioning process of the proton therapy system at Samsung Medical Center (SMC), we have developed a Monte Carlo simulation model of the proton therapy nozzles by using TOol for PArticle Simulation (TOPAS). At SMC proton therapy center, we have two gantry rooms with different types of nozzles: a multi-purpose nozzle and a dedicated scanning nozzle. Each nozzle has been modeled in detail following the geometry information provided by the manufacturer, Sumitomo Heavy Industries, Ltd. For this purpose, the novel features of TOPAS, such as the time feature or the ridge filter class, have been used, and the appropriate physics models for proton nozzle simulation have been defined. Dosimetric properties, like percent depth dose curve, spreadout Bragg peak (SOBP), and beam spot size, have been simulated and verified against measured beam data. Beyond the Monte Carlo nozzle modeling, we have developed an interface between TOPAS and the treatment planning system (TPS), RayStation. An exported radiotherapy (RT) plan from the TPS is interpreted by using an interface and is then translated into the TOPAS input text. The developed Monte Carlo nozzle model can be used to estimate the non-beam performance, such as the neutron background, of the nozzles. Furthermore, the nozzle model can be used to study the mechanical optimization of the design of the nozzle.

  1. Global Simulation of Bioenergy Crop Productivity: Analytical Framework and Case Study for Switchgrass

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Shujiang [ORNL; Kline, Keith L [ORNL; Nair, S. Surendran [University of Tennessee, Knoxville (UTK); Nichols, Dr Jeff A [ORNL; Post, Wilfred M [ORNL; Brandt, Craig C [ORNL; Wullschleger, Stan D [ORNL; Wei, Yaxing [ORNL; Singh, Nagendra [ORNL

    2013-01-01

    A global energy crop productivity model that provides geospatially explicit quantitative details on biomass potential and factors affecting sustainability would be useful, but does not exist now. This study describes a modeling platform capable of meeting many challenges associated with global-scale agro-ecosystem modeling. We designed an analytical framework for bioenergy crops consisting of six major components: (i) standardized natural resources datasets, (ii) global field-trial data and crop management practices, (iii) simulation units and management scenarios, (iv) model calibration and validation, (v) high-performance computing (HPC) simulation, and (vi) simulation output processing and analysis. The HPC-Environmental Policy Integrated Climate (HPC-EPIC) model simulated a perennial bioenergy crop, switchgrass (Panicum virgatum L.), estimating feedstock production potentials and effects across the globe. This modeling platform can assess soil C sequestration, net greenhouse gas (GHG) emissions, nonpoint source pollution (e.g., nutrient and pesticide loss), and energy exchange with the atmosphere. It can be expanded to include additional bioenergy crops (e.g., miscanthus, energy cane, and agave) and food crops under different management scenarios. The platform and switchgrass field-trial dataset are available to support global analysis of biomass feedstock production potential and corresponding metrics of sustainability.

  2. Global Simulation of Bioenergy Crop Productivity: Analytical framework and Case Study for Switchgrass

    Energy Technology Data Exchange (ETDEWEB)

    Nair, S. Surendran [University of Tennessee, Knoxville (UTK); Nichols, Jeff A. {Cyber Sciences} [ORNL; Post, Wilfred M [ORNL; Wang, Dali [ORNL; Wullschleger, Stan D [ORNL; Kline, Keith L [ORNL; Wei, Yaxing [ORNL; Singh, Nagendra [ORNL; Kang, Shujiang [ORNL

    2014-01-01

    Contemporary global assessments of the deployment potential and sustainability aspects of biofuel crops lack quantitative details. This paper describes an analytical framework capable of meeting the challenges associated with global scale agro-ecosystem modeling. We designed a modeling platform for bioenergy crops, consisting of five major components: (i) standardized global natural resources and management data sets, (ii) global simulation unit and management scenarios, (iii) model calibration and validation, (iv) high-performance computing (HPC) modeling, and (v) simulation output processing and analysis. A case study with the HPC- Environmental Policy Integrated Climate model (HPC-EPIC) to simulate a perennial bioenergy crop, switchgrass (Panicum virgatum L.) and global biomass feedstock analysis on grassland demonstrates the application of this platform. The results illustrate biomass feedstock variability of switchgrass and provide insights on how the modeling platform can be expanded to better assess sustainable production criteria and other biomass crops. Feedstock potentials on global grasslands and within different countries are also shown. Future efforts involve developing databases of productivity, implementing global simulations for other bioenergy crops (e.g. miscanthus, energycane and agave), and assessing environmental impacts under various management regimes. We anticipated this platform will provide an exemplary tool and assessment data for international communities to conduct global analysis of biofuel biomass feedstocks and sustainability.

  3. Sensitivity study of large-scale particle image velocimetry measurement of river discharge using numerical simulation

    Science.gov (United States)

    Hauet, Alexandre; Creutin, Jean-Dominique; Belleudy, Philippe

    2008-01-01

    SummaryThis study deals with the uncertainty of large-scale particle image velocimetry (LSPIV) measurements in rivers. LSPIV belongs to the methods of local remote sensing of rivers, like Radar- and Lidar-based techniques. These methods have many potential advantages, in comparison with classical river gauging, but they have a fundamental drawback: they are indirect measurements. As such they need to be assessed in reference to direct measurements. A first validation method consists in the comparison of LSPIV measurements with classic gauging results, in field and laboratory experiments. Unfortunately, in both cases, it is impossible in practice to control all the parameters and to distinguish the impact of the various error sources. In the present study we propose a more theoretical assessment of LSPIV potential through numerical simulation. The idea is simply to mathematically formulate the present state of knowledge of the measurement including both the physics of the phenomenon (the illuminated river) and the physics of the sensor (the camera and the PIV tracking). The dilemma about when to start this type of simulation is the following: The simulation is satisfactory if we can validate it which means to be able to compare simulations and observations over a wide range of conditions. The simulation is useful to get preliminary insights about the most important measurement conditions to organize validation studies. Our simulator is composed of three blocks: The river block represents the unidirectional river flow by the association of the EDM model and a theoretical vertical velocity profile giving a 3D velocity distribution. This hydraulic model is complemented by features representing free surface tracers, the illumination of the free-surface (shadows and sun reflection) and the effect of the wind. The camera block transforms the river state parameters into raster images according to the intrinsic and extrinsic parameters of the camera. The LSPIV analysis

  4. Experimental and simulation studies on the behavior of signal harmonics in magnetic particle imaging.

    Science.gov (United States)

    Murase, Kenya; Konishi, Takashi; Takeuchi, Yuki; Takata, Hiroshige; Saito, Shigeyoshi

    2013-07-01

    Our purpose in this study was to investigate the behavior of signal harmonics in magnetic particle imaging (MPI) by experimental and simulation studies. In the experimental studies, we made an apparatus for MPI in which both a drive magnetic field (DMF) and a selection magnetic field (SMF) were generated with a Maxwell coil pair. The MPI signals from magnetic nanoparticles (MNPs) were detected with a solenoid coil. The odd- and even-numbered harmonics were calculated by Fourier transformation with or without background subtraction. The particle size of the MNPs was measured by transmission electron microscopy (TEM), dynamic light-scattering, and X-ray diffraction methods. In the simulation studies, the magnetization and particle size distribution of MNPs were assumed to obey the Langevin theory of paramagnetism and a log-normal distribution, respectively. The odd- and even-numbered harmonics were calculated by Fourier transformation under various conditions of DMF and SMF and for three different particle sizes. The behavior of the harmonics largely depended on the size of the MNPs. When we used the particle size obtained from the TEM image, the simulation results were most similar to the experimental results. The similarity between the experimental and simulation results for the even-numbered harmonics was better than that for the odd-numbered harmonics. This was considered to be due to the fact that the odd-numbered harmonics were more sensitive to background subtraction than were the even-numbered harmonics. This study will be useful for a better understanding, optimization, and development of MPI and for designing MNPs appropriate for MPI.

  5. A simulation study provided sample size guidance for differential item functioning (DIF) studies using short scales.

    Science.gov (United States)

    Scott, Neil W; Fayers, Peter M; Aaronson, Neil K; Bottomley, Andrew; de Graeff, Alexander; Groenvold, Mogens; Gundy, Chad; Koller, Michael; Petersen, Morten A; Sprangers, Mirjam A G

    2009-03-01

    Differential item functioning (DIF) analyses are increasingly used to evaluate health-related quality of life (HRQoL) instruments, which often include relatively short subscales. Computer simulations were used to explore how various factors including scale length affect analysis of DIF by ordinal logistic regression. Simulated data, representative of HRQoL scales with four-category items, were generated. The power and type I error rates of the DIF method were then investigated when, respectively, DIF was deliberately introduced and when no DIF was added. The sample size, scale length, floor effects (FEs) and significance level were varied. When there was no DIF, type I error rates were close to 5%. Detecting moderate uniform DIF in a two-item scale required a sample size of 300 per group for adequate (>80%) power. For longer scales, a sample size of 200 was adequate. Considerably larger sample sizes were required to detect nonuniform DIF, when there were extreme FEs or when a reduced type I error rate was required. The impact of the number of items in the scale was relatively small. Ordinal logistic regression successfully detects DIF for HRQoL instruments with short scales. Sample size guidelines are provided.

  6. Effects of Solid Fraction on Droplet Wetting and Vapor Condensation: A Molecular Dynamic Simulation Study.

    Science.gov (United States)

    Gao, Shan; Liao, Quanwen; Liu, Wei; Liu, Zhichun

    2017-10-31

    Recently, numerous studies focused on the wetting process of droplets on various surfaces at a microscale level. However, there are a limited number of studies about the mechanism of condensation on patterned surfaces. The present study performed the dynamic wetting behavior of water droplets and condensation process of water molecules on substrates with different pillar structure parameters, through molecular dynamic simulation. The dynamic wetting results indicated that droplets exhibit Cassie state, PW state, and Wenzel state successively on textured surfaces with decreasing solid fraction. The droplets possess a higher static contact angle and a smaller spreading exponent on textured surfaces than those on smooth surfaces. The condensation processes, including the formation, growth, and coalescence of a nanodroplet, are simulated and quantitatively recorded, which are difficult to be observed by experiments. In addition, a wetting transition and a dewetting transition were observed and analyzed in condensation on textured surfaces. Combining these simulation results with previous theoretical and experimental studies will guide us to understand the hypostasis and mechanism of the condensation more clearly.

  7. Multislice simulations for in-situ HRTEM studies of nanostructured magnesium hydride at ambient hydrogen pressure

    Energy Technology Data Exchange (ETDEWEB)

    Surrey, Alexander, E-mail: a.surrey@ifw-dresden.de [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Schultz, Ludwig [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany); Institut für Festkörperphysik, Technische Universität Dresden, D-01062 Dresden (Germany); Rellinghaus, Bernd, E-mail: b.rellinghaus@ifw-dresden.de [IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, D-01171 Dresden (Germany)

    2017-04-15

    Highlights: • Multislice HRTEM contrast simulations of a windowed environmental cell. • Study of Mg and MgH2 nanocrystals as model system in hydrogen at ambient pressure. • Investigation of spatial resolution and contrast depending on specimen thickness, defocus, and hydrogen pressure. • Atomic resolution is expected for specimens as thin as 5  nm. - Abstract: The use of transmission electron microscopy (TEM) for the structural characterization of many nanostructured hydrides, which are relevant for solid state hydrogen storage, is hindered due to a rapid decomposition of the specimen upon irradiation with the electron beam. Environmental TEM allows to stabilize the hydrides by applying a hydrogen back pressure of up to 4.5 bar in a windowed environmental cell. The feasibility of high-resolution TEM (HRTEM) investigations of light weight metals and metal hydrides in such a “nanoreactor” is studied theoretically by means of multislice HRTEM contrast simulations using Mg and its hydride phase, MgH{sub 2}, as model system. Such a setup provides the general opportunity to study dehydrogenation and hydrogenation reactions at the nanoscale under technological application conditions. We analyze the dependence of both the spatial resolution and the HRTEM image contrast on parameters such as the defocus, the metal/hydride thickness, and the hydrogen pressure in order to explore the possibilities and limitations of in-situ experiments with windowed environmental cells. Such simulations may be highly valuable to pre-evaluate future experimental studies.

  8. Negotiating frame ambiguity: a study of simulated encounters in medical education.

    Science.gov (United States)

    Seale, Clive; Butler, Christopher C; Hutchby, Ian; Kinnersley, Paul; Rollnick, Stephen

    2007-01-01

    We report an investigation of the sociolinguistic characteristics of simulated encounters (role plays) in medical education, focusing in particular on frame negotiation. The role played by context in influencing the nature of out-of-frame activity is noted through comparison with another published study of simulations (Linell and Thunqvist 2003). While in general sustaining a role-playing frame that involved an orientation to exact mimicry of clinical situations, the interactional work done to sustain this appearance of 'authenticity' at certain moments was revealed by out-of-frame utterances. One participating doctor in particular used humor to exploit the ambiguous realism of the role-playing frame. The success of this doctor in acquiring and applying new communication behaviors problematizes the view that 'realism', achieved through mimicry, is solely responsible for the success of training interventions. The implications for studying other kinds of simulated encounters, including an outline for a program of research into the sociolinguistics of acting tasks in general, are outlined. Sociolinguistic researchers involved in observational studies of talk would benefit from adopting the view that role-played, rehearsed, and even scripted talk of the sort used in dramatic performance is a variety of naturally occurring data and therefore worthy of study.

  9. Finite element simulations with ANSYS workbench 17 theory, applications, case studies

    CERN Document Server

    Lee, Huei-Huang

    2017-01-01

    Finite Element Simulations with ANSYS Workbench 17 is a comprehensive and easy to understand workbook. Printed in full color, it utilizes rich graphics and step-by-step instructions to guide you through learning how to perform finite element simulations using ANSYS Workbench. Twenty seven real world case studies are used throughout the book. Many of these case studies are industrial or research projects that you build from scratch. Prebuilt project files are available for download should you run into any problems. Companion videos, that demonstrate exactly how to perform each tutorial, are also available. Relevant background knowledge is reviewed whenever necessary. To be efficient, the review is conceptual rather than mathematical. Key concepts are inserted whenever appropriate and summarized at the end of each chapter. Additional exercises or extension research problems are provided as homework at the end of each chapter. A learning approach emphasizing hands-on experiences spreads though this entire boo...

  10. Analysis of Shop Floor Performance through Discrete Event Simulation: A Case Study

    Directory of Open Access Journals (Sweden)

    Yeong Wei Ng

    2014-01-01

    Full Text Available Shop floor performance management is a method to ensure the effective utilization of people, processes, and equipment. Changes in the shop floor might have a positive or negative effect on production performance. Therefore, optimal shop floor operation is required to enhance shop floor performance and to ensure the long-term efficiency of the production process. This work presents a case study of a semiconductor industry. The punching department is modeled to investigate the effect of changes in the shop floor on production performance through discrete event simulation. The effects on the throughput rate, machine utilization, and labor utilization are studied by adjusting the volume of parts, number of operators, and flow pattern of parts in a series of models. Simulation results are tested and analyzed by using analysis of variance (ANOVA. The best model under changes in the shop floor is identified during the exploration of alternative scenarios.

  11. A Study of K- Factor Power Transformer Characteristics by Modeling Simulation

    Directory of Open Access Journals (Sweden)

    W. A. A. Salem

    2011-10-01

    Full Text Available Harmonic currents generated by nonlinear loads can cause overheating and premature failure in power transformers. K-factor transformers are specially designed to accommodate harmonic currents and offer protection against overheating caused by harmonics. They minimize harmonic current loss and have an additional thermal capacity of known limits. According to IEEE C57-110, the winding eddy current losses are considered proportional to the harmonic current squared times its harmonic number. K-factor is only an indicative value and the authors' main objective in this paper is to study the effect of harmonics on oil filled transformer and to simulate harmonic behavior using Matlab Simulink. A case study is simulated in order to investigate K-factor values with pumping loads, with and without the use of harmonic filters. Results are compared with measured values.

  12. A Parametric Study on Welding Process Simulation for Multi-pass welds in a Plate

    Energy Technology Data Exchange (ETDEWEB)

    Park, Won Dong; Bahn, Chi Bum; Kim, Ji Hun [Pusan National University, Busan (Korea, Republic of)

    2016-05-15

    EPRI (MRP-316, 317) (1,2) and USNRC (NUREG-2162)(3) have performed related studies for FEA models to predict the weld residual stress distribution. In this work, a systematic parametric study was performed to find out how major assumptions and conditions used in the simulation could affect the weld residual stress distribution. 2- dimensional simulation was conducted by using commercial FEA software, ABAQUS(4) , for multi-pass Alloy 82 welds performed in a stainless steel plate (EPRI MRP-316, P-4, phase 1). From the previous results, we could make the following conclusions. 1. The method of applying power density is more realistic than predefined temperature. 2. It seems that annealing effect reduces the transverse direction weld residual stress (S33). However more detailed analyses for annealing effect are needed.

  13. A comparative study of divergence cleaning methods of magnetic field in the solar coronal numerical simulation

    Directory of Open Access Journals (Sweden)

    Xueshang eFeng

    2016-03-01

    Full Text Available This paper presents a comparative study of divergence cleaning methods of magnetic field in the solar coronal three-dimensional numerical simulation. For such purpose, the diffusive method, projection method, generalized Lagrange multiplier method and constrained-transport method are used. All these methods are combined with a finite-volume scheme based on a six-component grid system in spherical coordinates. In order to see the performance between the four divergence cleaning methods, solar coronal numerical simulation for Carrington rotation 2056 has been studied. Numerical results show that the average relative divergence error is around $10^{-4.5}$ for the constrained-transport method, while about $10^{-3.1}- 10^{-3.6}$ for the other three methods. Although there exist some differences in the average relative divergence errors for the four employed methods, our tests show they can all produce basic structured solar wind.

  14. The TESS (Tandem Experiment Simulation Studies) computer code user's manual

    Energy Technology Data Exchange (ETDEWEB)

    Procassini, R.J. (California Univ., Berkeley, CA (USA). Dept. of Nuclear Engineering); Cohen, B.I. (Lawrence Livermore National Lab., CA (USA))

    1990-06-01

    TESS (Tandem Experiment Simulation Studies) is a one-dimensional, bounded particle-in-cell (PIC) simulation code designed to investigate the confinement and transport of plasma in a magnetic mirror device, including tandem mirror configurations. Mirror plasmas may be modeled in a system which includes an applied magnetic field and/or a self-consistent or applied electrostatic potential. The PIC code TESS is similar to the PIC code DIPSI (Direct Implicit Plasma Surface Interactions) which is designed to study plasma transport to and interaction with a solid surface. The codes TESS and DIPSI are direct descendants of the PIC code ES1 that was created by A. B. Langdon. This document provides the user with a brief description of the methods used in the code and a tutorial on the use of the code. 10 refs., 2 tabs.

  15. Study of the heat transfer in solids using infrared photothermal radiometry and simulation by COMSOL Multiphysics.

    Science.gov (United States)

    Suarez, V; Hernández Wong, J; Nogal, U; Calderón, A; Rojas-Trigos, J B; Juárez, A G; Marín, E

    2014-01-01

    It is reported the study of the heat transfer through a homogeneous and isotropic solid exited by square periodic light beam on its front surface. For this, we use the Infrared Photothermal Radiometry in order to obtain the evolution of the temperature difference on the rear surface of three samples, silicon, copper and wood, as a function of the exposure time. Also, we solved the heat transport equation for this problem with the boundary conditions congruent with the physical situation, by means of numerical simulation based in finite element analysis. Our results show a good agreement between the experimental and numerical simulated results, which demonstrate the utility of this methodology for the study of the thermal response of solids. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. OWL: A scalable Monte Carlo simulation suite for finite-temperature study of materials

    Science.gov (United States)

    Li, Ying Wai; Yuk, Simuck F.; Cooper, Valentino R.; Eisenbach, Markus; Odbadrakh, Khorgolkhuu

    The OWL suite is a simulation package for performing large-scale Monte Carlo simulations. Its object-oriented, modular design enables it to interface with various external packages for energy evaluations. It is therefore applicable to study the finite-temperature properties for a wide range of systems: from simple classical spin models to materials where the energy is evaluated by ab initio methods. This scheme not only allows for the study of thermodynamic properties based on first-principles statistical mechanics, it also provides a means for massive, multi-level parallelism to fully exploit the capacity of modern heterogeneous computer architectures. We will demonstrate how improved strong and weak scaling is achieved by employing novel, parallel and scalable Monte Carlo algorithms, as well as the applications of OWL to a few selected frontier materials research problems. This research was supported by the Office of Science of the Department of Energy under contract DE-AC05-00OR22725.

  17. Simulation study of irradiated Si sensors equipped with metal- overhang for applications in LHC environment

    CERN Document Server

    Chatterji, Sudeep; Bhardwaj, Ashutosh; Srivastava-Ajay, K; Kumar, Ashish; Jha, Manoj Kumar; Shivpuri, R K; Khanna, S L

    2004-01-01

    The performance of metal-overhang (MO) equipped silicon micro-strip sensors, after irradiation for the preshower detector to be used in the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC), CERN, has been studied through simulations. Detailed calculations using Hamburg model have allowed the parameterization of these effects and helped to simulate the operation scenario of MO equipped sensors over ten years of LHC operation. The utility of overhanging metal extension as junction termination technique after space charge sign inversion (SCSI) has been explored in detail for the first time in this work. Several interesting results like a shift in the optimal oxide thickness in MO equipped structures after irradiation have been reported. The comparison of dielectric and semi-insulator passivated MO equipped structures after irradiation has been studied. Also, the impact of various crucial geometrical parameters like device depth (W//N), width of back N **+ layer used for ohmic contact (W/...

  18. Simulation and Feasibility Study of Flow Sensor on Flexible Polymer for Healthcare Application.

    Science.gov (United States)

    Maji, Debashis; Das, Soumen

    2013-12-01

    Development of microfabrication technology, along with an ever-increasing demand for reliable, low-cost clinical healthcare has led to the realization of various BioMEMS devices. Present study aims at developing a flexible flow sensor on polymer substrate to monitor real-time blood flow and determine plague formation satisfying sensitivity, biocompatibility, and reliability requirements. Transient simulation of temperature and velocity profile of the thermal-anemometer-based sensor wrapped around the catheter has been studied. Initial fabrication of the sensor over polydimethylsiloxane (PDMS) polymer along with thermal coefficient of resistance (TCR) measurement and flow sensing over straight heater has also been performed. The simulation and fabrication works show promising results toward successful development of a flow sensor for effective healthcare delivery.

  19. Using simulation to promote nursing students' learning of work organization and people management skills: a case-study.

    Science.gov (United States)

    Warland, Jane

    2011-05-01

    Simulation is becoming widely used in nurse education. However, reports concerning its use focus almost exclusively on describing experiences with high-fidelity manikin simulation used to teach students a range of psychomotor skills and clinical procedures. Simulation has enormous potential as a learning tool and can provide much more than just a basis for safely learning clinical skills. This paper gives a case-study of use of a simulation exercise that is designed to develop nursing students' work organization and people management skills. It also discusses student evaluation of the simulation exercise. Student engagement with this type of simulation and their feedback suggest that skills obtained during the simulation are transferable into and valuable for their clinical placements. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. RAGE Hydrocode Modeling of Asteroid Mitigation: new simulations with parametric studies for uncertainty quantification

    Science.gov (United States)

    Weaver, R.; Plesko, C. S.; Gisler, G. R.

    2013-12-01

    We are performing detailed hydrodynamic simulations of the interaction from a strong explosion with sample Asteroid objects. The purpose of these simulations is to apply modern hydrodynamic codes that have been well verified and validated (V&V) to the problem of mitigating the hazard from a potentially hazardous object (PHO), an asteroid or comet that is on an Earth crossing orbit. The code we use for these simulations is the RAGE code from Los Alamos National Laboratory [1-6]. Initial runs were performed using a spherical object. Next we ran simulations using the shape form from a known asteroid: 25143 Itokawa. This particular asteroid is not a PHO but we use its shape to consider the influence of non-spherical objects. The initial work was performed using 2D cylindrically symmetric simulations and simple geometries. We then performed a major fully 3D simulation. For an Itokawa size object (~500 m) and an explosion energies ranging from 0.5 - 1 megatons, the velocities imparted to all of the PHO "rocks" in all cases were many m/s. The velocities calculated were much larger than escape velocity and would preclude re-assembly of the fragments. The dispersion of the asteroid remnants is very directional from a surface burst, with all fragments moving away from the point of the explosion. This detail can be used to time the intercept for maximum movement off the original orbit. Results from these previous studies will be summarized for background. In the new work presented here we show a variety of parametric studies around these initial simulations. We modified the explosion energy by +/- 20% and varied the internal composition from a few large "rocks" to several hundred smaller rocks. The results of these parametric studies will be presented. We have also extended our work [6],[7] to stand-off nuclear bursts and will present the initial results for the energy deposition by a generic source into the non-uniform composition asteroid. The goal of this new work is to

  1. Modeling and Transient Simulation of Unified Power Flow Controllers (UPFC) in Power System Studies

    OpenAIRE

    Kawkabani, B.; Pannatier, Y.; Simond, J.-J.

    2007-01-01

    The present paper describes the modeling of Unified Power Flow Controllers (UPFC) for studying the steady-state and transient behavior of electrical networks equipped with FACTS devices. Detailed time-domain simulations are carried out on four model power systems (single-machine system and multi-machine systems including the IEEE-14 bus test system), to illustrate the control features of these devices and their influence to increase power transfer and improve system stability. The interaction...

  2. Study on Tensile Properties of Nanoreinforced Epoxy Polymer: Macroscopic Experiments and Nanoscale FEM Simulation Prediction

    OpenAIRE

    Zhenqing Wang; Fang Liu; Wenyan Liang; Limin Zhou

    2013-01-01

    The effect of nanosilica contents on mechanical properties of the epoxy matrix with some nanoparticle aggregations was studied in macroscopic experiments and nanoscale simulation, particularly with regard to the effective modulus and ultimate stress. Three analytical models were used to obtain the effective elastic modulus of nanoparticle-reinforced composites. Based on Monte-Carlo method, the special program for the automatic generation of 2D random distribution particles without overlapping...

  3. Microbial Safety of Low Water Activity Foods: Study of Simulated and Durban Household Samples

    OpenAIRE

    Ijabadeniyi, O. A.; Pillay, Y.

    2017-01-01

    Sixty household low water activity foods were examined and a simulative study was conducted in a high sugar, low aw almond and macadamia butter to determine the survival of Bacillus cereus and Staphylococcus aureus ATCC 25923. Results obtained from 60 low aw samples collected at household level had some significant differences (P≤0,05) within food categories amongst the various tests. Spices had the highest number of aerobic bacteria, aerobic spore-formers, anaerobic spore-formers, and S. aur...

  4. Laser Induced C60 Cage Opening Studied by Semiclassical Dynamics Simulation

    Directory of Open Access Journals (Sweden)

    Yusheng Dou

    2011-01-01

    Full Text Available Laser induced opening of the C60 cage is studied by a semiclassical electron-radiation-ion dynamics technique. The simulation results indicate that the C60 cage is abruptly opened immediately after laser excitation. The opening of the C60 cage induces a quick increase in kinetic energy and a sharp decrease in electronic energy, suggesting that the breaking of the C60 cage efficiently heats up the cluster and enhances the thermal fragmentation of C60 fullerene.

  5. Modeling and Simulation Optimization and Feasibility Studies for the Neutron Detection without Helium-3 Project

    Energy Technology Data Exchange (ETDEWEB)

    Ely, James H.; Siciliano, Edward R.; Swinhoe, Martyn T.; Lintereur, Azaree T.

    2013-01-01

    This report details the results of the modeling and simulation work accomplished for the ‘Neutron Detection without Helium-3’ project during the 2011 and 2012 fiscal years. The primary focus of the project is to investigate commercially available technologies that might be used in safeguards applications in the relatively near term. Other technologies that are being developed may be more applicable in the future, but are outside the scope of this study.

  6. Monte Carlo simulation of nuclear energy study (II). Annual report on Nuclear Code Evaluation Committee

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-01-01

    In the report, research results discussed in 1999 fiscal year at Nuclear Code Evaluation Committee of Nuclear Code Research Committee were summarized. Present status of Monte Carlo simulation on nuclear energy study was described. Especially, besides of criticality, shielding and core analyses, present status of applications to risk and radiation damage analyses, high energy transport and nuclear theory calculations of Monte Carlo Method was described. The 18 papers are indexed individually. (J.P.N.)

  7. Corrosion Inhibition Study of Al-Cu-Ni Alloy in Simulated Sea-Water ...

    African Journals Online (AJOL)

    A study on the inhibition of Al-Cu-Ni alloy in simulated sea-water environment was investigated using Sodium Chromate as inhibitor. The inhibitor concentration was varied as control, 0.25, 0.5, 1.0, 1.5 and 2.0 Molar. Al-Cu-Ni alloy was sand cast into cylindrical bars of 20 mm x 300 mm dimension. The corrosion of the ...

  8. A Simulation Study of Conformal Cooling Channels in Plastic Injection Molding

    OpenAIRE

    Omar A. Mohamed, S.H. Masood, Abul Saifullah

    2013-01-01

    In injection molding process, the cooling channel performance is one of the most crucial factors because it has significant effect on both production rate and the quality of the plastic part. In order to reduce the cycle time, and control the uniform distribution of temperature, it is necessary to create conformal cooling channels, which conform to the shape of the mold cavity and core. This paper presents a simulation study of different types of cooling channe...

  9. Numerical study and simulation of nano-bubble formation with CFD

    OpenAIRE

    Hamid Reza Ghorbani; Vahid Ghorbani

    2014-01-01

    In recent years, microbubble and nanobubble technologies have drawn great attention due to their wide applications in many fields of science and technology, such as water treatment, biomedical engineering, and nanomaterials. In this work, we numerically studied nano-bubble formation process by entering air into a submerged orifice in a cylindrical vessel. The simulations were carried out using SOLA-VOF method. In this code, complete form of Navier-stocks equations was predicted two dimensions...

  10. DESIGN STUDY AND SIMULATION OF A DIGITAL FIBER COMMUNICATION SYSTEM USING (OPTISYSTEM.10)

    OpenAIRE

    Dr. Shehab A. Kadhim*, Dr. Zeyad A. Saleh, Asmaa M. Raoof, Alaa T. Lateef

    2016-01-01

    Recent digital fiber optic communication systems address modulation and detection techniques for high spectral efficiency and robustness against transmission impairments. The proposed objective of this project is to design studies and analyze the simulation model of a Digital Fiber Communication System using (optisystem.10), as well as the front-end components and units used to implement them. Using the most suitable settings of the system which include laser transmitter with (1310nm) and (...

  11. Tight binding simulation study on zigzag single-walled carbon nanotubes

    Science.gov (United States)

    Sharma, Deepa; Jaggi, Neena; Gupta, Vishu

    2018-01-01

    Tight binding simulation studies using the density functional tight binding (DFTB) model have been performed on various zigzag single-walled carbon-nanotubes (SWCNTs) to investigate their electronic properties using DFTB module of the Material Studio Software version 7.0. Various combinations of different eigen-solvers and charge mixing schemes available in the DFTB Module have been tried to chalk out the electronic structure. The analytically deduced values of the bandgap of (9, 0) SWCNT were compared with the experimentally determined value reported in the literature. On comparison, it was found that the tight binding approximations tend to drastically underestimate the bandgap values. However, the combination of Anderson charge mixing method with standard eigensolver when implemented using the smart algorithm was found to produce fairly close results. These optimized model parameters were then used to determine the band structures of various zigzag SWCNTs. (9, 0) Single-walled Nanotube which is extensively being used for sensing NH3, CH4 and NO2 has been picked up as a reference material since its experimental bandgap value has been reported in the literature. It has been found to exhibit a finite energy bandgap in contrast to its expected metallic nature. The study is of utmost significance as it not only probes and validates the simulation route for predicting suitable properties of nanomaterials but also throws light on the comparative efficacy of the different approximation and rationalization quantum mechanical techniques used in simulation studies. Such simulation studies if used intelligently prove to be immensely useful to the material scientists as they not only save time and effort but also pave the way to new experiments by making valuable predictions.

  12. Symmetry Properties of Proton Velocity Distributions: a Vlasov Simulation Study of the Ion Cyclotron Instability

    Science.gov (United States)

    Araneda, J. A.; López, R. A.; Vinas, A. F.

    2014-12-01

    The ion cyclotron instability is driven by a sufficiently large proton temperature anisotropy, generating a spectrum of counterpropagating field-aligned ion cyclotron fluctuations. In this work, we use low-noise one-dimensional electromagnetic Vlasov simulations in a magnetized and collisionless plasma of fluid electrons and one ion species to study the evolution of proton velocity distributions during the thermal relaxation process. Special attention is given to deviations from initial bi-Maxwellian shapes.

  13. Simulation study of a basic integrated inventory problem with quality improvement and lead time reduction

    OpenAIRE

    Van Volsem, Sofie; Verdiesen, Johannes

    2010-01-01

    In this paper, we investigate the trade-off between investing in product quality improvement and lead time reduction in a B2B single-supplier, single-buyer environment. To this end, a discrete event simulation model is proposed, based on the integrated inventory model defined in Ouyang et al. (2006). Furthermore, the possibility of using alternative failure mechanisms and capital investment functions are studied. ity of using alternative failure mechanisms and capital investment functions...

  14. Computational study on ice growth inhibition of Antarctic bacterium antifreeze protein using coarse grained simulation

    OpenAIRE

    Nguyen, Hung; Le, Ly; Ho, Tu Bao

    2014-01-01

    Antarctic bacterium antifreeze proteins (AFPs) protect and support the survival of cold-adapted organisms by binding and inhibiting the growth of ice crystals. The mechanism of the anti-freezing process in a water environment at low temperature of Antarctic bacterium AFPs remains unclear. In this research, we study the effects of Antarctic bacterium AFPs by coarse grained simulations solution at a temperature range from 262 to 273K. The results indicated that Antarctic bacterium AFPs were ful...

  15. The effect of trochlear dysplasia on patellofemoral biomechanics: a cadaveric study with simulated trochlear deformities.

    Science.gov (United States)

    Van Haver, Annemieke; De Roo, Karel; De Beule, Matthieu; Labey, Luc; De Baets, Patrick; Dejour, David; Claessens, Tom; Verdonk, Peter

    2015-06-01

    Trochlear dysplasia appears in different geometrical variations. The Dejour classification is widely used to grade the severity of trochlear dysplasia and to decide on treatment. To investigate the effect of trochlear dysplasia on patellofemoral biomechanics and to determine if different types of trochlear dysplasia have different effects on patellofemoral biomechanics. Controlled laboratory study. Trochlear dysplasia was simulated in 4 cadaveric knees by replacing the native cadaveric trochlea with different types of custom-made trochlear implants, manufactured with 3-dimensional printing. For each knee, 5 trochlear implants were designed: 1 implant simulated the native trochlea (control condition), and 4 implants simulated 4 types of trochlear dysplasia. The knees were subjected to 3 biomechanical tests: a squat simulation, an open chain extension simulation, and a patellar stability test. The patellofemoral kinematics, contact area, contact pressure, and stability were compared between the control condition (replica implants) and the trochlear dysplastic condition and among the subgroups of trochlear dysplasia. The patellofemoral joint in the trochlear dysplastic group showed increased internal rotation, lateral tilt, and lateral translation; increased contact pressures; decreased contact areas; and decreased stability when compared with the control group. Within the trochlear dysplastic group, the implants graded as Dejour type D showed the largest deviations for the kinematical parameters, and the implants graded as Dejour types B and D showed the largest deviations for the patellofemoral contact areas and pressures. Patellofemoral kinematics, contact area, contact pressure, and stability are significantly affected by trochlear dysplasia. Of all types of trochlear dysplasia, the models characterized with a pronounced trochlear bump showed the largest deviations in patellofemoral biomechanics. Investigating the relationship between the shape of the trochlea and

  16. Molecular Dynamics Simulation Study of the Selectivity of a Silica Polymer for Ibuprofen

    Directory of Open Access Journals (Sweden)

    Riccardo Concu

    2016-07-01

    Full Text Available In the past few years, the sol-gel polycondensation technique has been increasingly employed with great success as an alternative approach to the preparation of molecularly imprinted materials (MIMs. The main aim of this study was to study, through a series of molecular dynamics (MD simulations, the selectivity of an imprinted silica xerogel towards a new template—the (±-2-(P-Isobutylphenyl propionic acid (Ibuprofen, IBU. We have previously demonstrated the affinity of this silica xerogel toward a similar molecule. In the present study, we simulated the imprinting process occurring in a sol-gel mixture using the Optimized Potentials for Liquid Simulations-All Atom (OPLS-AA force field, in order to evaluate the selectivity of this xerogel for a template molecule. In addition, for the first time, we have developed and verified a new parameterisation for the Ibuprofen® based on the OPLS-AA framework. To evaluate the selectivity of the polymer, we have employed both the radial distribution functions, interaction energies and cluster analyses.

  17. Monte Carlo simulation using the PENELOPE code with an ant colony algorithm to study MOSFET detectors

    Energy Technology Data Exchange (ETDEWEB)

    Carvajal, M A; Palma, A J [Departamento de Electronica y Tecnologia de Computadores, Universidad de Granada, E-18071 Granada (Spain); Garcia-Pareja, S [Servicio de Radiofisica Hospitalaria, Hospital Regional Universitario ' Carlos Haya' , Avda Carlos Haya, s/n, E-29010 Malaga (Spain); Guirado, D [Servicio de RadiofIsica, Hospital Universitario ' San Cecilio' , Avda Dr Oloriz, 16, E-18012 Granada (Spain); Vilches, M [Servicio de Fisica y Proteccion Radiologica, Hospital Regional Universitario ' Virgen de las Nieves' , Avda Fuerzas Armadas, 2, E-18014 Granada (Spain); Anguiano, M; Lallena, A M [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain)], E-mail: carvajal@ugr.es, E-mail: garciapareja@gmail.com, E-mail: dguirado@ugr.es, E-mail: mvilches@ugr.es, E-mail: mangui@ugr.es, E-mail: ajpalma@ugr.es, E-mail: lallena@ugr.es

    2009-10-21

    In this work we have developed a simulation tool, based on the PENELOPE code, to study the response of MOSFET devices to irradiation with high-energy photons. The energy deposited in the extremely thin silicon dioxide layer has been calculated. To reduce the statistical uncertainties, an ant colony algorithm has been implemented to drive the application of splitting and Russian roulette as variance reduction techniques. In this way, the uncertainty has been reduced by a factor of {approx}5, while the efficiency is increased by a factor of above 20. As an application, we have studied the dependence of the response of the pMOS transistor 3N163, used as a dosimeter, with the incidence angle of the radiation for three common photons sources used in radiotherapy: a {sup 60}Co Theratron-780 and the 6 and 18 MV beams produced by a Mevatron KDS LINAC. Experimental and simulated results have been obtained for gantry angles of 0 deg., 15 deg., 30 deg., 45 deg., 60 deg. and 75 deg. The agreement obtained has permitted validation of the simulation tool. We have studied how to reduce the angular dependence of the MOSFET response by using an additional encapsulation made of brass in the case of the two LINAC qualities considered.

  18. Drones at the service for training on mass casualty incident: A simulation study.

    Science.gov (United States)

    Fernandez-Pacheco, Antonio Nieto; Rodriguez, Laura Juguera; Price, Mariana Ferrandini; Perez, Ana Belen Garcia; Alonso, Nuria Perez; Rios, Manuel Pardo

    2017-06-01

    Mass casualty incidents (MCI) are characterized by a large number of victims with respect to the resources available. In this study, we aimed to analyze the changes produced in the self-perception of students who were able to visualize aerial views of a simulation of a MCI. A simulation study, mixed method, was performed to compare the results from an ad hoc questionnaire. The 35 students from the Emergency Nursing Master from the UCAM completed a questionnaire before and after watching an MCI video with 40 victims in which they had participated. The main variable measured was the change in self-perception (CSP). The CSP occurred in 80% (28/35) of the students (P = .001). Students improved their individual (P = .001) and group (P = .006) scores. They also described that their personal performance had better results than the group performance (P = .047). The main conclusion of this study is that drones could lead to CSP and appraisal of the MCI simulation participants.

  19. Impact of simulation training on Jordanian nurses' performance of basic life support skills: A pilot study.

    Science.gov (United States)

    Toubasi, Samar; Alosta, Mohammed R; Darawad, Muhammad W; Demeh, Waddah

    2015-09-01

    Providing efficient basic life support (BLS) training is crucial for practicing nurses who provide direct patient care. Nevertheless, data addressing the impact of BLS courses on the skills and performance of Jordanian nurses are scarce. This study aimed to assess the effectiveness of a BLS simulation training on Jordanian nurses' skill improvement in cardiopulmonary resuscitation. A prospective quasi-experimental, single group pretest-posttest design was used to study the effect of BLS simulation; using a 9-item checklist; on the spot training; American Heart Association, on a group of Jordanian nurses. A pre-test was conducted following a CPR scenario to test the skills using 9-item checklist extrapolated from the American Heart Association guidelines. After debriefing, an interactive on spot training was provided. Later, participants undertook an unscheduled post-test after four weeks that included the same nine items. Thirty registered nurses with a mean clinical experience of 6.1years participated in the study. Comparing pre-test (M=4.6, SD=2.9, range=0 to 9) with post-test results (M=7.5, SD=1.7, range=4 to 9) showed an overall improvement in skills and BLS scores after the simulation training program (t=7.4, df=29, pskills and performance among Jordanian nurses. A refreshment BLS training session for nurses is highly recommended to guarantee nurses' preparedness in actual CPR scenarios. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. The Communicability of Graphical Alternatives to Tabular Displays of Statistical Simulation Studies

    Science.gov (United States)

    Cook, Alex R.; Teo, Shanice W. L.

    2011-01-01

    Simulation studies are often used to assess the frequency properties and optimality of statistical methods. They are typically reported in tables, which may contain hundreds of figures to be contrasted over multiple dimensions. To assess the degree to which these tables are fit for purpose, we performed a randomised cross-over experiment in which statisticians were asked to extract information from (i) such a table sourced from the literature and (ii) a graphical adaptation designed by the authors, and were timed and assessed for accuracy. We developed hierarchical models accounting for differences between individuals of different experience levels (under- and post-graduate), within experience levels, and between different table-graph pairs. In our experiment, information could be extracted quicker and, for less experienced participants, more accurately from graphical presentations than tabular displays. We also performed a literature review to assess the prevalence of hard-to-interpret design features in tables of simulation studies in three popular statistics journals, finding that many are presented innumerately. We recommend simulation studies be presented in graphical form. PMID:22132184

  1. Monte Carlo simulation using the PENELOPE code with an ant colony algorithm to study MOSFET detectors.

    Science.gov (United States)

    Carvajal, M A; García-Pareja, S; Guirado, D; Vilches, M; Anguiano, M; Palma, A J; Lallena, A M

    2009-10-21

    In this work we have developed a simulation tool, based on the PENELOPE code, to study the response of MOSFET devices to irradiation with high-energy photons. The energy deposited in the extremely thin silicon dioxide layer has been calculated. To reduce the statistical uncertainties, an ant colony algorithm has been implemented to drive the application of splitting and Russian roulette as variance reduction techniques. In this way, the uncertainty has been reduced by a factor of approximately 5, while the efficiency is increased by a factor of above 20. As an application, we have studied the dependence of the response of the pMOS transistor 3N163, used as a dosimeter, with the incidence angle of the radiation for three common photons sources used in radiotherapy: a (60)Co Theratron-780 and the 6 and 18 MV beams produced by a Mevatron KDS LINAC. Experimental and simulated results have been obtained for gantry angles of 0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees and 75 degrees. The agreement obtained has permitted validation of the simulation tool. We have studied how to reduce the angular dependence of the MOSFET response by using an additional encapsulation made of brass in the case of the two LINAC qualities considered.

  2. Validation studies of the DOE-2 Building Energy Simulation Program. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, R.; Winkelmann, F.

    1998-06-01

    This report documents many of the validation studies (Table 1) of the DOE-2 building energy analysis simulation program that have taken place since 1981. Results for several versions of the program are presented with the most recent study conducted in 1996 on version DOE-2.1E and the most distant study conducted in 1981 on version DOE-1.3. This work is part of an effort related to continued development of DOE-2, particularly in its use as a simulation engine for new specialized versions of the program such as the recently released RESFEN 3.1. RESFEN 3.1 is a program specifically dealing with analyzing the energy performance of windows in residential buildings. The intent in providing the results of these validation studies is to give potential users of the program a high degree of confidence in the calculated results. Validation studies in which calculated simulation data is compared to measured data have been conducted throughout the development of the DOE-2 program. Discrepancies discovered during the course of such work has resulted in improvements in the simulation algorithms. Table 2 provides a listing of additions and modifications that have been made to various versions of the program since version DOE-2.1A. One of the most significant recent changes in the program occurred with version DOE-2.1E. An improved algorithm for calculating the outside surface film coefficient was implemented. In addition, integration of the WINDOW 4 program was accomplished resulting in improved ability in analyzing window energy performance. Validation and verification of a program as sophisticated as DOE-2 must necessarily be limited because of the approximations inherent in the program. For example, the most accurate model of the heat transfer processes in a building would include a three-dimensional analysis. To justify such detailed algorithmic procedures would correspondingly require detailed information describing the building and/or HVAC system and energy plant parameters

  3. Comparison of multiple-criteria decision-making methods - results of simulation study

    Directory of Open Access Journals (Sweden)

    Michał Adamczak

    2016-12-01

    Full Text Available Background: Today, both researchers and practitioners have many methods for supporting the decision-making process. Due to the conditions in which supply chains function, the most interesting are multi-criteria methods. The use of sophisticated methods for supporting decisions requires the parameterization and execution of calculations that are often complex. So is it efficient to use sophisticated methods? Methods: The authors of the publication compared two popular multi-criteria decision-making methods: the  Weighted Sum Model (WSM and the Analytic Hierarchy Process (AHP. A simulation study reflects these two decision-making methods. Input data for this study was a set of criteria weights and the value of each in terms of each criterion. Results: The iGrafx Process for Six Sigma simulation software recreated how both multiple-criteria decision-making methods (WSM and AHP function. The result of the simulation was a numerical value defining the preference of each of the alternatives according to the WSM and AHP methods. The alternative producing a result of higher numerical value  was considered preferred, according to the selected method. In the analysis of the results, the relationship between the values of the parameters and the difference in the results presented by both methods was investigated. Statistical methods, including hypothesis testing, were used for this purpose. Conclusions: The simulation study findings prove that the results obtained with the use of two multiple-criteria decision-making methods are very similar. Differences occurred more frequently in lower-value parameters from the "value of each alternative" group and higher-value parameters from the "weight of criteria" group.

  4. Effect of sway and yaw motion on perception and control; A multi-simulator, follow-up study

    NARCIS (Netherlands)

    Ellerbroek, J.; Stroosma, O.; Wentink, M.; Groen, E.L.

    2006-01-01

    The three Dutch research institutes NLR, TNO and TU Delft are collaborating to perform a multi-simulator follow-up study aimed at investigating the influence of yaw and translational motion cues in helicopter- and general flight-simulation. In this study, new experimental results will be combined

  5. Simulation and experimental study of CVD process for low temperature nanocrystalline silicon carbide coating

    Energy Technology Data Exchange (ETDEWEB)

    Kaushal, Amit; Prakash, Jyoti, E-mail: jprakash@barc.gov.in; Dasgupta, Kinshuk; Chakravartty, Jayanta K.

    2016-07-15

    Highlights: • Parametric simulation was carried out for specially designed CVD reactor. • Effect of fluid velocity, heat flow and concentration were studied in CVD reactor. • Coating study carried out using low temperature and environmental safe CVD process. • Dense and uniform nanocrystalline SiC film was coated on zircaloy substrate. - Abstract: There is a huge requirement for development of a coating technique in nuclear industry, which is environmentally safe, economical and applicable to large scale components. In this view, simulation of gas-phase behavior in specially designed CVD reactor was carried out using computational tool, COMSOL. There were two important zones in CVD reactor first one is precursor vaporization zone and second one is coating zone. Optimized parameters for coating were derived from the simulation of gas phase dynamics in both zone of CVD reactor. The overall effect of fluid velocity, heat flow and concentration profile showed that Re = 54 is the optimum reaction condition for uniform coating in CVD system. In CVD coating experiments a synthesized halogen free, non-toxic and non-corrosive silicon carbide precursor was used. Uniform coating of SiC was obtained on zircaloy substrate at 900 °C using as synthesized organosilicon precursor. The X-ray diffraction and scanning electron microscopy analysis show that dense nano crystalline SiC film was deposited on zircaloy substrate.

  6. Simulation and Study of Power Quality Issues in a Fixed Speed Wind Farm Substation

    Directory of Open Access Journals (Sweden)

    T. Magesh

    2015-01-01

    Full Text Available Power quality issues associated with the fixed speed wind farm substation located at Coimbatore district are investigated as the wind generators are tripping frequently. The investigations are carried out using two power quality analyzers, Fluke 435 and Dranetz PX5.8, with one of them connected at group control breaker of the 110 kV feeder and the other at the selected 0.69 kV generator busbar during the period of maximum power generation. From the analysis of the recorded data it is found that sag, swell, and transients are the major events which are responsible for the tripping of the generators. In the present study, simulation models for wind, turbine, shaft, pitch mechanism, induction generator, and grid are developed using DIgSILENT. Using the turbine characteristics, a two-dimensional lookup table is designed to generate a reference pitch angle necessary to simulate the power curve of the passive stall controlled wind turbine. Various scenarios and their effects on the performance of the wind farm are studied and validated with the recorded data and waveforms. The simulation model will be useful for the designers for planning and development of the wind farm before implementation.

  7. Baccalaureate nursing students' perspectives of peer tutoring in simulation laboratory, a Q methodology study.

    Science.gov (United States)

    Li, Ting; Petrini, Marcia A; Stone, Teresa E

    2017-12-11

    The study aim was to identify the perceived perspectives of baccalaureate nursing students toward the peer tutoring in the simulation laboratory. Insight into the nursing students' experiences and baseline data related to their perception of peer tutoring will assist to improve nursing education. Q methodology was applied to explore the students' perspectives of peer tutoring in the simulation laboratory. A convenience P-sample of 40 baccalaureate nursing students was used. Fifty-eight selected Q statements from each participant were classified into the shape of a normal distribution using an 11-point bipolar scale form with a range from -5 to +5. PQ Method software analyzed the collected data. Three discrete factors emerged: Factor I ("Facilitate or empower" knowledge acquisition), Factor II ("Safety Net" Support environment), and Factor III ("Mentoring" learn how to learn). The findings of this study support and indicate that peer tutoring is an effective supplementary strategy to promote baccalaureate students' knowledge acquisition, establishing a supportive safety net and facilitating their abilities to learn in the simulation laboratory. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Experimental and Monte Carlo simulation studies of open cylindrical radon monitoring device using CR-39 detector.

    Science.gov (United States)

    Rehman, Fazal-ur; Jamil, K; Zakaullah, M; Abu-Jarad, F; Mujahid, S A

    2003-01-01

    There are several methods of measuring radon concentrations but nuclear track detector cylindrical dosimeters are widely employed. In this investigation, the consequence of effective volumes of the dosimeters on the registration of alpha tracks in a CR-39 detector was studied. In a series of experiments an optimum radius for a CR-39-based open cylindrical radon dosimeter was found to be about 3 cm. Monte Carlo simulation techniques have been employed to verify the experimental results. In this context, a computer code Monte Carlo simulation dosimetry (MOCSID) was developed. Monte Carlo simulation experiments gave the optimum radius of the dosimeters as 3.0 cm. The experimental results are in good agreement with those obtained by Monte Carlo design calculations. In addition to this, plate-out effects of radon progeny were also studied. It was observed that the contribution of radon progeny (218Po and 214Po) plated-out on the wall of the dosimeters increases with an increase of dosimeter radii and then decrease to 0 at a radius of about 3 cm if a point detector has been installed at the center of the dosimeter base. In the code MOCSID different types of random number generators were employed. The results of this research are very useful for designing an optimum size of radon dosimeters.

  9. Experimental and Monte Carlo simulation studies of open cylindrical radon monitoring device using CR-39 detector

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Fazal-ur- E-mail: fazalr@kfupm.edu.sa; Jamil, K.; Zakaullah, M.; Abu-Jarad, F.; Mujahid, S.A

    2003-07-01

    There are several methods of measuring radon concentrations but nuclear track detector cylindrical dosimeters are widely employed. In this investigation, the consequence of effective volumes of the dosimeters on the registration of alpha tracks in a CR-39 detector was studied. In a series of experiments an optimum radius for a CR-39-based open cylindrical radon dosimeter was found to be about 3 cm. Monte Carlo simulation techniques hav been employed to verify the experimental results. In this context, a computer code Monte Carlo simulation dosimetry (MOCSID) was developed. Monte Carlo simulation experiments gave the optimum radius of the dosimeters as 3.0 cm. The experimental results are in good agreement with those obtained by Monte Carlo design calculations. In addition to this, plate-out effects of radon progeny were also studied. It was observed that the contribution of radon progeny ({sup 218}Po and {sup 214}Po) plated-out on the wall of the dosimeters increases with an increase of dosimeter radii and then decrease to 0 at a radius of about 3 cm if a point detector has been installed at the center of the dosimeter base. In the code MOCSID different types of random number generators were employed. The results of this research are very useful for designing an optimum size of radon dosimeters.

  10. Performance simulation studies of a realistic model of the CBM silicon tracking system

    Energy Technology Data Exchange (ETDEWEB)

    Kotynia, Anna [GSI, Darmstadt (Germany); Collaboration: CBM-Collaboration

    2012-07-01

    One of the most challenging fields of modern high-energy physics is exploration of the phase diagram of strongly interacting matter. In order to study the dynamics of phase diagram at high net baryon densities, the CBM experiment will be performed with high-energy nucleus-nucleus collisions. Efficient charged particle tracking and high momentum resolution are central performance requirements of the CBM Silicon Tracking System (STS). The aim of ongoing layout studies is to design a highly granular and low mass detector system that can track the 1000 charged particles that are typically generated in Au+Au collisions at 25 GeV/u projectile energy. A low mass detector is required to achieve a momentum resolution down to 1%. The simulations of detector response which have been developed include of detector responce include complete chain of physical processes caused by a charged particle traversing the detector - from charge creation in the silicon to the digital output signals. We present the concept of STS geometry, tools used for simulation of realistic detector response together with discussion about results of such simulations.

  11. Temperature dependence of magnetic order in Fe/(Ga,Mn)As studied by Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Polesya, Svitlana; Minar, Jan; Ebert, Hubert [LMU Muenchen, Dept. Chemie und Biochemie/Phys. Chemie, Butenandtstrasse 11, D-81377 Muenchen (Germany); Back, Christian [Institut fuer Experimentelle Physik, Univ. Regensburg (Germany)

    2008-07-01

    The magnetic order of the heterogeneous interface system (GaMn)As/Fe at finite temperatures has been studied by Monte Carlo simulations. The ground state magnetic properties were determined within ab initio electronic structure calculations using the SPR-TB-KKR Green's function method. All calculations have been performed for the semi-infinite system of (GaMn)As with 5 % Mn covered by a 7 ML Fe film. The temperature dependent properties of this system (with and without external magnetic field) have been studied using MC simulation. The exchange coupling within the Fe and (GaMn)As subsystems were found to be dominantly long-range ferromagnetic whereas the coupling of Fe and Mn moments close to the interface is strongly antiferromagnetic. The Monte Carlo simulations lead to a Curie temperature of about 1000 K for the Fe film. Within the (GaMn)As subsystem due to the polarisation induced by the Fe film the average magnetisation at room temperature is still about 70 % of its T=0 value for several layers close to the interface. These results are in full agreement with recent experimental findings.

  12. A study on the shielding of lodine 131 using Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Dong Gun; Yang, Seoung Oh; Kim, Jung Ki; Lee, Sang Ho; Choi, Hyung Seok; Bae, Cheol Woo [Dongnam Institute of Radiological and Medical Sciences Cancer Center, Busan (Korea, Republic of)

    2014-06-15

    This study was designated to investigate the Bremsstrahlung and radiation dose by beta rays. Radiation attenuation from I-131 treatment ward was analyzed using radio protective apron. Shielding materials which is included lead or water were simulated in Monte Carlo Simulation then the spectrum on interaction was analyzed. The shielding materials were categorized according to the thickness. 0.25 mm and 0.5 mm thick lead and 0.1 mm and 0.2 mm thick water shielding materials were configured in Monte Carlo Simulation for this study. Only lead shielding method and water plus lead shielding method were carried. As a results, when 0.5 mm thick lead shielding method was performed, the radiation dose was similar to the results with water plus lead shielding method. In case of using 0.25 mm thick lead shielding, the shielding effect was somewhat less. However, that shielding method cause dose reduction of about 60% compare with non-shielding material.

  13. Evaluation of Al-Najaf Hospital Intersection Performance Using Simulation model: Case Study

    Directory of Open Access Journals (Sweden)

    Hamid Athab Eedan Al-Jameel

    2016-03-01

    Full Text Available Traffic congestion is a widely spreading problem through the world. It is mainly observed around intersections in urban areas. In this study, Al-Najaf Hospital (Ibn Blal intersection has been evaluated because it is considered the congested T-intersection on Kufa-Nafa road. This T-intersection suffers from high congestion especially in the morning peak. This could be due to a lot of centers of activities (trip generation and attractive on that road such as University of Kufa, four hospitals and other facilities. Although the Highway Capacity Manual (HCM 2000 suffers from several shortcomings and limitations, it is used widely in the evaluation of intersections in Iraq. On the other hand, simulation models have been proved to be accurate tools in the evaluation of intersections. Therefore, a simulation model (S-Paramics model has been used to assess the performance of the current intersection. Then, the simulation model was calibrated with field data. Data was collected from the intersection using video camera installing over Al-Najaf Hospital building. The results of this study show that the developed model clearly mimics the reality. Then, different alternatives have been implemented using the developed model. Consequently, the construction of an overpass coming from Najaf-Kufa road towards Al-Sahlaa road is the best alternative with protecting U-turn.

  14. Simulation and study of power quality issues in a fixed speed wind farm substation.

    Science.gov (United States)

    Magesh, T; Chellamuthu, C

    2015-01-01

    Power quality issues associated with the fixed speed wind farm substation located at Coimbatore district are investigated as the wind generators are tripping frequently. The investigations are carried out using two power quality analyzers, Fluke 435 and Dranetz PX5.8, with one of them connected at group control breaker of the 110 kV feeder and the other at the selected 0.69 kV generator busbar during the period of maximum power generation. From the analysis of the recorded data it is found that sag, swell, and transients are the major events which are responsible for the tripping of the generators. In the present study, simulation models for wind, turbine, shaft, pitch mechanism, induction generator, and grid are developed using DIgSILENT. Using the turbine characteristics, a two-dimensional lookup table is designed to generate a reference pitch angle necessary to simulate the power curve of the passive stall controlled wind turbine. Various scenarios and their effects on the performance of the wind farm are studied and validated with the recorded data and waveforms. The simulation model will be useful for the designers for planning and development of the wind farm before implementation.

  15. Mental flexibility impairment in drivers with early Alzheimer's disease: A simulator-based study

    Directory of Open Access Journals (Sweden)

    Virginie Etienne

    2013-07-01

    Full Text Available After memory impairment, one of the most common troubles of early Alzheimer's disease (AD is the impairment of executive functioning. However, it can have major consequences on daily life, notably on the driving activity. The present study focused on one important executive function involved in driving: mental flexibility; and considered how this impairment can affect driving. Ten patients with early AD were matched with 29 healthy older drivers. All participants were given an evaluation of mental flexibility through neuropsychological tests and an experimental test developed on a static driving simulator. The experiment was divided in two conditions; one without mental flexibility and another condition with a mental flexibility demand. AD patients showed impairments in the neuropsychological tests evaluating mental flexibility. These deficits are linked to the deficits they showed in the driving simulator flexibility tests. This study contributes to the understanding of mental flexibility mechanisms and on their role in driving activity. It also confirms that the driving simulator is a suitable tool to explore cognitive disorders and driving ability.

  16. Heat Transfer Study of Heat-Integrated Distillation Column (HIDiC) Using Simulation Techniques

    Science.gov (United States)

    Pulido, Jeffrey León; Martínez, Edgar Leonardo; Wolf, Maria Regina; Filho, Rubens Maciel

    2011-08-01

    Separation processes is largely used in petroleum refining and alcohol industries. Distillation columns consume a huge amount of energy in industrial process. Therefore, the concept of Heat-Integrated Distillation Column (HIDiC) was studied using simulation techniques in order to overcome this drawback. In this configuration the column is composed for two concentric sections called rectifying and stripping. The heat transfer is conducted from the rectifying section (which works at higher pressure and temperature) to the stripping section (which works at lower pressure and temperature) using the heat present in the process and decreasing the energy charge required by the reboiler. The HIDiC column offers great potential to reduce energy consumption compared to conventional columns. However, the complexity of the internal configuration requires the development of rigorous works that enable a better understanding of the column operation. For this reason, techniques of simulation were used through of computational software. The current work presents a heat transfer study in a concentric stage of a HIDiC column. The results obtained by Aspen Plus and CFD simulation showed the internal heat transfer in a concentric tray as a promissory configuration in order to decrease energy consumption in distillation processes.

  17. Study on the Gap Flow Simulation in EDM Small Hole Machining with Ti Alloy

    Directory of Open Access Journals (Sweden)

    Shengfang Zhang

    2017-01-01

    Full Text Available In electrical discharge machining (EDM process, the debris removed from electrode material strongly affects the machining efficiency and accuracy, especially for the deep small hole machining process. In case of Ti alloy, the debris movement and removal process in gap flow between electrodes for small hole EDM process is studied in this paper. Based on the solid-liquid two-phase flow equation, the mathematical model on the gap flow field with flushing and self-adaptive disturbation is developed. In our 3D simulation process, the count of debris increases with number of EDM discharge cycles, and the disturbation generated by the movement of self-adaptive tool in the gap flow is considered. The methods of smoothing and remeshing are also applied in the modeling process to enable a movable tool. Under different depth, flushing velocity, and tool diameter, the distribution of velocity field, pressure field of gap flow, and debris movement are analyzed. The statistical study of debris distribution under different machining conditions is also carried out. Finally, a series of experiments are conducted on a self-made machine to verify the 3D simulation model. The experiment results show the burn mark at hole bottom and the tapered wall, which corresponds well with the simulating conclusion.

  18. Experimental and Simulation Studies of Hydrodynamic Tunneling of Ultra-Relativistic Protons

    CERN Document Server

    Burkart, Florian; Schmidt, Ruediger; Shutov, Alexander; Tahir, Naeem; Wollmann, Daniel; Zerlauth, Markus

    2015-01-01

    The expected damage due to the release of the full LHC beam energy at a single aperture bottleneck has been studied. These studies have shown that the range of the 7 TeV LHC proton beam is significantly extended compared to that of a single proton due to hydrodynamic tunneling effect. For instance, it was evaluated that the protons and their showers will penetrate up to a length of 25 m in solid carbon compared to a static range of around 3 m. To check the validity of these simulations, beam- target heating experiments using the 440 GeV proton beam generated by the SPS were performed at the HiRadMat test facility at CERN. Solid copper targets were facially irradiated by the beam and measurements confirmed hydrodynamic tunneling of the protons and their showers. Simulations have been done by running the energy deposition code FLUKA and the 2D hydrodynamic code, BIG2, iteratively. Very good agreement has been found between the simulations and the experimental results providing confidence in the validity of the ...

  19. Design and performance/measurement simulation studies for a ER-2 sunphotometer

    Science.gov (United States)

    Reagan, J. A.; Gao, Q.; Ehsani, A.

    1994-01-01

    Work and results, including developed software, obtained under this grant (NAG 2-620) have been reported in various progress reports, an M.S. Thesis, and software programs. The purpose of this final report is simply to provide a documented listing of what has already been reported. This includes the following: (1) Conceptual Design and Simulation of a Spectral Sunphotometer for the ER-2 Aircraft; (2) Continued Simulation and Design Studies for an ER-2 Sunphotometer; and (3) Simulation and Performance Studies of a Spectra Sunphotometer for the ER-2 Aircraft. Also, software and computational results for modeling airmass and diffuse light effects due to aerosols were provided in support of NASA ARC research on the effects of aerosols resulting from the Pinatubo volcanic eruptions. The references for these articles are as follows: (1) Post Pinatubo Optical Depth Spectra vs. Latitude and Vortex Structure; and (2) Pinatubo and Pre-Pinatubo Optical-Depth Spectra -- Mauna Loa Measurements, Comparisons, Inferred Particle Size Distributions, Radiative Effects, and Relationships to Lidar Data.

  20. PURIFICATION OF CRUDE GLYCEROL FROM INDUSTRIAL WASTE: EXPERIMENTAL AND SIMULATION STUDIES

    Directory of Open Access Journals (Sweden)

    WAN NOR ROSLAM WAN ISAHAK

    2016-08-01

    Full Text Available In this study, the purification of crude glycerol as a by-product of transesterification reaction was investigated. The first purification stage of the crude glycerol was achieved by employing the neutralization method, followed by microfiltration using 0.45µm filter membrane. Only glycerol peak could be detected by high performance liquid chromatography analysis which indicating that the neutralization step enabled to removal of excess homogeneous catalyst as well as the unreacted free fatty acids from crude glycerol samples. However, the free ions from salt and catalyst were then eliminated through an ion exchange process using two types of Amberlite resins to produce higher glycerol purity up to 99.4%. The purity of glycerol was confirmed by the other analysis such as the Fourier transform infrared, United States Pharmacopoeia and American society for testing and materials methods. The simulation studies were applied using Super-Pro-Designer 7.0 software which can provide the data for scale up to industrial scale. The P2 and P5 simulation process gives a higher purity of pure glycerol of 98.35 wt.% and 99.27 wt%, respectively were generated after through several combinatorial purification steps. The combination between the experimental and simulation process showed a good way to investigate the laboratory experiment input for possible industry scale in future.

  1. A Study of Soil Line Simulation from Landsat Images in Mixed Grassland

    Directory of Open Access Journals (Sweden)

    Xulin Guo

    2013-09-01

    Full Text Available The mixed grassland in Canada is characterized by low to medium green vegetation cover, with a large amount of canopy background, such as non-photosynthetic vegetation residuals (litter, bare soil, and ground level biological crust. It is a challenge to extract the canopy information from satellite images because of the influence of canopy background. Therefore, this study aims to extract a soil line, a representation of bare soil with litter and soil crust in the surface, from Landsat images to reduce the background effect. Field work was conducted in the West Block of Grasslands National Park (GNP in Canada, which represents the northern mixed grassland from late June to early July 2005. Six TM images with either no or only a small amount of cloud content were collected in 2005. In this study, soil lines were extracted directly from images by quantile regression and the (R, NIRmin method. The results show that, (1 both cloud and cloud shadow have obvious influence on simulating soil line automatically from images; (2 green up and late senescence seasons are relatively better for soil line simulation; (3 the (R, NIRmin method is better for soil line simulation than quantile regression to extract green biomass or green cover information.

  2. A comparative study of processing simulated and experimental data in elastic laser light scattering.

    Science.gov (United States)

    Popovici, M A; Mincu, N; Popovici, A

    1999-03-15

    The intensity of the laser light scattered by a suspension of biological particles undergoing Brownian motion contains information about their size distribution function and optical properties. We used several methods (implemented in MathCAD programs), including a new one, to invert the Fredholm integral equation of the first kind, which represents the angular dependence of the elastic scattering of light. The algorithms were first tested on different sets of simulated data. Experimental data were obtained using biological samples and an experimental arrangement which are briefly described. We study the stability of the inversion procedures relative to the noise levels, and compute the first two moments of the retrieved size distribution function. A comparison of the results corresponding to simulated and experimental data is done, to select the best processing algorithm.

  3. Simobiz-Simulation Tool to Study the Impact of Small Satellites in Mobile Market

    Science.gov (United States)

    Burlacu, M.-M.; Kohlenberg, J.; Prathaban, M.

    2008-08-01

    Interest in small satellites is growing fast world- wide. Businesses, governments, universities and other organizations around the world are starting their own small satellite programs. The surveys conducted by the space agencies and universities shows a promising increase in the use of small satellites for commercial applications. More number of operators offers or plans to offer mobile phone services by satellite. With the help of cost effective small satellite, mobile operators can be able to provide the services cheaper. Hence, it is always interesting to study the effect of low cost small satellite over the mobile market. In this article, we present SmartSim (Small Satellites Mobile Market Simulator) - the new module of Simobiz business simulation game, in which we have implemented two operators, a normal satellite operator and a nanosatellite operator, with specific terminals and services. Our main focus in this work is to understand the future market of small satellite in mobile telecommunication network.

  4. A study on experiment and numerical simulation of heat exchanger in heating furnace

    Directory of Open Access Journals (Sweden)

    Z. C. Lv

    2018-01-01

    Full Text Available In this paper, air preheater is used the research object and its heat transfer law is studied by experiment and numerical simulation. The experimental data showed that with the increases of inlet air velocity, the comprehensive heat transfer coefficient and heat transfer efficiency increase, but the temperature efficiency decreases and the resistance loss on the air side increases. The numerical simulation results showed that the larger the diameter of the tube, the better the heat transfer effect. When horizontal spacing in the range of 290 - 305 mm and longitudinal spacing is 70 - 90 mm, the heat transfer effect is best. The optimized heat exchanger structure is that diameter is 60 mm, horizontal spacing is 300 mm, longitudinal spacing is 90 mm. As the inlet air flow rate increases, the heat transfer efficiency increases, but the temperature efficiency decreases and the resistance loss on the air side increases.

  5. Finite element simulations with ANSYS workbench 15 theory, applications, case studies

    CERN Document Server

    Lee, Huei-Huang

    2014-01-01

    Finite Element Simulations with ANSYS Workbench 15 is a comprehensive and easy to understand workbook. It utilizes step-by-step instructions to help guide you to learn finite element simulations. Twenty seven real world case studies are used throughout the book. Many of these cases are industrial or research projects you build from scratch. An accompanying DVD contains all the files you may need if you have trouble. Relevant background knowledge is reviewed whenever necessary. To be efficient, the review is conceptual rather than mathematical, short, yet comprehensive. Key concepts are inserted whenever appropriate and summarized at the end of each chapter. Additional exercises or extension research problems are provided as homework at the end of each chapter. A learning approach emphasizing hands-on experiences spreads through this entire book. A typical chapter consists of 6 sections. The first two provide two step-by-step examples. The third section tries to complement the exercises by providing a more sy...

  6. Finite element simulations with ANSYS workbench 14 theory, applications, case studies

    CERN Document Server

    Lee, Huei-Huang

    2012-01-01

    Finite Element Simulations with ANSYS Workbench 14 is a comprehensive and easy to understand workbook. It utilizes step-by-step instructions to help guide readers to learn finite element simulations. Twenty seven case studies are used throughout the book. Many of these cases are industrial or research projects the reader builds from scratch. An accompanying DVD contains all the files readers may need if they have trouble. Relevant background knowledge is reviewed whenever necessary. To be efficient, the review is conceptual rather than mathematical, short, yet comprehensive. Key concepts are inserted whenever appropriate and summarized at the end of each chapter. Additional exercises or extension research problems are provided as homework at the end of each chapter. A learning approach emphasizing hands-on experiences spreads though this entire book. A typical chapter consists of 6 sections. The first two provide two step-by-step examples. The third section tries to complement the exercises by providing a mo...

  7. Corrections and Design Studies of Borehole Logging Tools with the help of Monte Carlo Simulations

    Science.gov (United States)

    Reinhardt, Heiko

    2014-06-01

    Borehole logging tools are used for measuring a detailed record of a geological formation that is penetrated by a borehole. Values of interest of a geological formation are for example its density, chemical composition and porosity. Density of a formation can be measured using tools based on a chemical CS-137 gamma ray source. Porosity can be measured using a chemical AmBe neutron source. The resulting measurement of the tool, for example the density of a formation, has to be corrected for borehole influences such as borehole fluid or borehole size. These corrections depend on the individual tool design. The best way to calculate this vast number of corrections is using Monte-Carlo simulations. The software of choice is the MCNP5 package(1) . At Antares Datensysteme simulations are further used in pre design studies, to get the best physical layout of a tool.

  8. A simulation study of the effects of acaricides and vaccination on Boophilus cattle-tick populations.

    Science.gov (United States)

    Lodos, J; Ochagavia, M E; Rodriguez, M; De La Fuente, J

    1999-01-01

    This paper describes a simulation model to evaluate different control strategies for Boophilus microplus. The model combines a dynamic life-history module for tick-population dynamics with other modules for vaccination, sterile-hybrid larval release and use of acaricide dipping vats. The tick life-history module considers the cattle's nutritional level and allows for distribution of ticks by age at all stages of growth. Appropriately, the model was sensitive to host resistance and to host-nutritional status. The validity of the life-history module--as well as that of the vaccination and acaricide dipping--vats modules--was demonstrated by comparing simulated and real data for several geographical locations in Cuba and Brazil. Optimum tick-control strategies for the first year of vaccination were designed and the effect of long-term vaccination on tick population was also studied.

  9. Gridsampler – A Simulation Tool to Determine the Required Sample Size for Repertory Grid Studies

    Directory of Open Access Journals (Sweden)

    Mark Heckmann

    2017-01-01

    Full Text Available The repertory grid is a psychological data collection technique that is used to elicit qualitative data in the form of attributes as well as quantitative ratings. A common approach for evaluating multiple repertory grid data is sorting the elicited bipolar attributes (so called constructs into mutually exclusive categories by means of content analysis. An important question when planning this type of study is determining the sample size needed to a discover all attribute categories relevant to the field and b yield a predefined minimal number of attributes per category. For most applied researchers who collect multiple repertory grid data, programming a numeric simulation to answer these questions is not feasible. The gridsampler software facilitates determining the required sample size by providing a GUI for conducting the necessary numerical simulations. Researchers can supply a set of parameters suitable for the specific research situation, determine the required sample size, and easily explore the effects of changes in the parameter set.

  10. Parametric Study of Stay Cables of a Bridge Under Simulated Spatially Correlated Turbulent Wind

    Directory of Open Access Journals (Sweden)

    A. Pozos-Estrada

    Full Text Available Abstract The main objective of this work is to carry out a parametric study of stay cables of a bridge under simulated spatially correlated buffeting forces. This vibration mechanism is simulated with an Autoregressive and Moving Average (ARMA model, and applied to mathematical models of the stay cables of the tallest cable-stayed bridge in Mexico. The use of auxiliary damping devices to mitigate vibration is evaluated. The analysis results showed that the use of a more realistic model to represent and characterize the variation in space and time of the fluctuating wind, which is not capture by the white noise or harmonic functions, is advantageous and offers a new alternative to evaluate the structural response of stay cables without and with dampers. The implications of the analyses results in the structural behavior of the stay cables of the bridge are discussed.

  11. Numerical Simulation and Experimental Study of Deep Bed Corn Drying Based on Water Potential

    Directory of Open Access Journals (Sweden)

    Zhe Liu

    2015-01-01

    Full Text Available The concept and the model of water potential, which were widely used in agricultural field, have been proved to be beneficial in the application of vacuum drying model and have provided a new way to explore the grain drying model since being introduced to grain drying and storage fields. Aiming to overcome the shortcomings of traditional deep bed drying model, for instance, the application range of this method is narrow and such method does not apply to systems of which pressure would be an influential factor such as vacuum drying system in a way combining with water potential drying model. This study established a numerical simulation system of deep bed corn drying process which has been proved to be effective according to the results of numerical simulation and corresponding experimental investigation and has revealed that desorption and adsorption coexist in deep bed drying.

  12. Numerical study of MPS method with large eddy simulation for fluid solid coupling problem

    Science.gov (United States)

    YANG, Chao; ZHANG, Huaixin; YAO, Huilan

    2017-02-01

    The Moving-Particle Semi-implicit method (MPS) is a kind of meshless Lagrangian calculation method. This method uses particles instead of mesh. In the pretreatment it works simply and conveniently and has high computational efficiency. In practical engineering, many of fluid problems are turbulent flows. Large eddy simulation is a major means of studying turbulence. Fluid-structure coupling is an independent branch of mechanics combined with fluid dynamics and solid mechanics, which is the hot and difficult area of research in many fields at present. In this paper, for the numerical simulation of turbulent flow with interaction of fluid-structure, the modified MPS-LES method is applied in two dimensional dam-break problem. It proves that MPS-LES method can be extended on solving the fluid-solid coupled problem.

  13. Simulation Study of Discharging PCM Ceiling Panels through Night - time Radiative Cooling

    DEFF Research Database (Denmark)

    Bourdakis, Eleftherios; Kazanci, Ongun Berk; Grossule, F.

    2016-01-01

    demand. In the present simulation study, the coupling of nighttime radiative cooling with PCM for cooling an office room was investigated. For cooling water through nighttime radiative cooling two types of solar panels were utilized, an unglazed solar collector and photovoltaic/thermal (PV/T) panels...... provided by the PV/T panels was 43 W/m2 for Copenhagen, while for Milan and Athens it was 36 W/m2 and 34 W/m2, respectively. The cooling power of the unglazed solar collector was negligible. Finally, the total electricity produced in Copenhagen for the simulated period was 371 kWh, while for Milan...... and increase use of renewable energy sources. The aim is that by 2020 all new buildings should be nearly zero-energy buildings. A solution that could contribute to this is the combination of photovoltaic panels for the production of electricity and phase change material (PCM) for the reduction of peak cooling...

  14. Analytical and simulation studies of 2D asymmetric simple exclusion process

    Science.gov (United States)

    Ding, Zhong-Jun; Yu, Shao-Long; Zhu, Kongjin; Ding, Jian-Xun; Chen, Bokui; Shi, Qin; Lu, Xiao-Shan; Jiang, Rui; Wang, Bing-Hong

    2018-02-01

    Two species of particles driven perpendicularly and interacting through hardcore exclusion on the 2D lattice is studied. Each particle has three moving directions without the back step. Under periodic boundary conditions, an intermediate phase has been found at which some particles could move along the border of jamming stripes. We have performed mean field analysis for the moving and intermediate phase respectively. The analytical results agree with the simulation results well. The empty site moves along the interface of jamming stripes when the system only has one empty site. The average movement of empty site in one Monte Carlo step (MCS) has been analyzed through the master equation. Under open boundary conditions, the system exhibits moving and jamming phases. The critical injection probability αc shows non-monotonically against the forward moving probability q. The analytical results of average velocity, the density and the flow rate against the injection probability in the moving phase also agree with simulation results well.

  15. Compositional Simulation of In-Situ Combustion EOR: A Study of Process Characteristics

    DEFF Research Database (Denmark)

    Jain, Priyanka; Stenby, Erling Halfdan; von Solms, Nicolas

    2010-01-01

    combustion simulation is used. Preceding research work primarily focused on a kinetic model that was based on six components and incorporated four chemical reactions. However, modeling of a thermal process as complex as In-situ combustion requires in-depth understanding of detailed reaction kinetics...... and multidisciplinary process data. This paper extends the understanding of previous research done in this domain by performing the process simulations to study further the impact of oxidation reactions and combustion reactions of crude oils along with their saturate, aromatic, resin, and asphaltene (SARA) fractions....... This incorporates fourteen pseudo components and fourteen reactions (distributed amongst thermal cracking, low temperature oxidation and high temperature oxidation). The paper presents a set of derivative plots indicating that reservoir process characterization in terms of thermal behavior of oil can be well...

  16. A simulated study on the performance of diesel engine with ethanol-diesel blend fuel

    Directory of Open Access Journals (Sweden)

    Zhang Zhi-Qiang

    2013-01-01

    Full Text Available This paper describes the simulated study on atomization, wall-film formation, combustion and emission forming process of ethanol-diesel blend fuels in a high speed light duty diesel engine. The result shows that increased ethanol volume percentage of the blend fuels could improve atomization and reduce wall-film formation. However, in the meanwhile, with the increased ethanol volume percentage, low heat values of blend fuels decrease, while both total heat releases and cylinder pressures drop. By adding codes into the FIRE software, the NOx and soot formation region mass fractions are outputted. The simulated results display a good correlation with the NOx and soot formation. Besides, the NOx, soot and CO emissions decrease with the increased ethanol volume percentage. The power output of engine penalize, while energy utilization of blend fuels improve and combustion noise reduce, owing to the increased ethanol volume percentage.

  17. Estimation of non-linear growth models by linearization: a simulation study using a Gompertz function.

    Science.gov (United States)

    Vuori, Kaarina; Strandén, Ismo; Sevón-Aimonen, Marja-Liisa; Mäntysaari, Esa A

    2006-01-01

    A method based on Taylor series expansion for estimation of location parameters and variance components of non-linear mixed effects models was considered. An attractive property of the method is the opportunity for an easily implemented algorithm. Estimation of non-linear mixed effects models can be done by common methods for linear mixed effects models, and thus existing programs can be used after small modifications. The applicability of this algorithm in animal breeding was studied with simulation using a Gompertz function growth model in pigs. Two growth data sets were analyzed: a full set containing observations from the entire growing period, and a truncated time trajectory set containing animals slaughtered prematurely, which is common in pig breeding. The results from the 50 simulation replicates with full data set indicate that the linearization approach was capable of estimating the original parameters satisfactorily. However, estimation of the parameters related to adult weight becomes unstable in the case of a truncated data set.

  18. Nonlinear Fluid Simulation Study of Stimulated Raman and Brillouin Scatterings in Shock Ignition

    Science.gov (United States)

    Ren, Chuang; Hao, Liang; Yan, Rui; Li, Jun; Liu, Wenda

    2017-10-01

    We developed a new nonlinear fluid laser-plasma-instability code FLAME using a multi-fluid plasma model combined with full electromagnetic wave equations. The completed one-dimensional (1D) version of FLAME was used to study laser-plasma instabilities in shock ignition. The simulations results showed that absolute Stimulated Raman Scattering (SRS) modes growing near the quarter-critical surface were saturated by Langmuir-wave Decay Instabilities (LDI) and pump depletion. The ion-acoustic waves from LDI acted as seeds of Stimulated Brillouin Scattering (SBS), which displayed a bursting pattern and caused strong pump depletion. Re-scattering of SRS was also observed in a high temperature case. These results largely agreed with corresponding Particle-in-Cell simulations. Work funded by DOE (DE-SC0012316), NSF (PHY-1314734), NSFC (11642020, 11621202), and Science Challenge Project (No. JCKY2016212A505).

  19. Photoinduced dissociation of cyclobutane thymine dimer studied by semiclassical dynamics simulation.

    Science.gov (United States)

    Dou, Yusheng; Xiong, Shanshan; Wu, Weifeng; Yuan, Shuai; Tang, Hong

    2010-10-05

    Photoinduced dissociation of the thymine dimer is studied in a semiclassical dynamics simulation. The simulation follows excitation of an isolated thymine dimer by a 25 fs fwhm laser pulse, and finds that dissociation proceeds via an asynchronously concerted mechanism, in which the C(5)-C(5)' bond breaks soon after application of the laser pulse, followed by cleavage of the C(6)-C(6)' bond. The dissociation results in two thymine monomers, one in an electronically excited state and the other in the ground state. The former decays to the electronic ground state through an avoided crossing induced by deformation of the pyrimidine ring at the C(5)' and C(6)' sites. Copyright 2010 Elsevier B.V. All rights reserved.

  20. A search for the dominant heat conducting phonon modes in graphene: An atomistic simulation study

    Science.gov (United States)

    Zhang, Hengji; Cho, Kyeongjae

    2011-03-01

    We have performed an equilibrium molecular dynamic (MD) simulation study to investigate phonon thermal transport in graphene at 300K with Green-Kubo method. Using a newly optimized reactive empirical bond order carbon potential (Lindsay, et al. Physical Review B 81, 205441, 2010), our calculated thermal conductivity (TC) of defect free graphene is about 3000 W/mK in good agreement with experiments(~ 3000-5000 W/mK). A maximum of ~ 1000 fold reduction in TC is possible to achieve for graphene with defects and surrounding viscous medium. As we decompose the in-plane and out-plane phonon vibration modes of graphene in MD simulations, the out of plane vibration modes (ZA phonon) contribute to about 50% of the overall TC. This large contribution from ZA modes is explained with density of states analysis. We have clarified a recent controversy on which polarization mode in graphene is the main heat carrier.