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Sample records for improving simulation techniques

  1. Improved importance sampling technique for efficient simulation of digital communication systems

    Science.gov (United States)

    Lu, Dingqing; Yao, Kung

    1988-01-01

    A new, improved importance sampling (IIS) approach to simulation is considered. Some basic concepts of IS are introduced, and detailed evolutions of simulation estimation variances for Monte Carlo (MC) and IS simulations are given. The general results obtained from these evolutions are applied to the specific previously known conventional importance sampling (CIS) technique and the new IIS technique. The derivation for a linear system with no signal random memory is considered in some detail. For the CIS technique, the optimum input scaling parameter is found, while for the IIS technique, the optimum translation parameter is found. The results are generalized to a linear system with memory and signals. Specific numerical and simulation results are given which show the advantages of CIS over MC and IIS over CIS for simulations of digital communications systems.

  2. An Improved Simulated Annealing Technique for Enhanced Mobility in Smart Cities

    Directory of Open Access Journals (Sweden)

    Hayder Amer

    2016-06-01

    Full Text Available Vehicular traffic congestion is a significant problem that arises in many cities. This is due to the increasing number of vehicles that are driving on city roads of limited capacity. The vehicular congestion significantly impacts travel distance, travel time, fuel consumption and air pollution. Avoidance of traffic congestion and providing drivers with optimal paths are not trivial tasks. The key contribution of this work consists of the developed approach for dynamic calculation of optimal traffic routes. Two attributes (the average travel speed of the traffic and the roads’ length are utilized by the proposed method to find the optimal paths. The average travel speed values can be obtained from the sensors deployed in smart cities and communicated to vehicles via the Internet of Vehicles and roadside communication units. The performance of the proposed algorithm is compared to three other algorithms: the simulated annealing weighted sum, the simulated annealing technique for order preference by similarity to the ideal solution and the Dijkstra algorithm. The weighted sum and technique for order preference by similarity to the ideal solution methods are used to formulate different attributes in the simulated annealing cost function. According to the Sheffield scenario, simulation results show that the improved simulated annealing technique for order preference by similarity to the ideal solution method improves the traffic performance in the presence of congestion by an overall average of 19.22% in terms of travel time, fuel consumption and CO2 emissions as compared to other algorithms; also, similar performance patterns were achieved for the Birmingham test scenario.

  3. An Improved Simulated Annealing Technique for Enhanced Mobility in Smart Cities.

    Science.gov (United States)

    Amer, Hayder; Salman, Naveed; Hawes, Matthew; Chaqfeh, Moumena; Mihaylova, Lyudmila; Mayfield, Martin

    2016-06-30

    Vehicular traffic congestion is a significant problem that arises in many cities. This is due to the increasing number of vehicles that are driving on city roads of limited capacity. The vehicular congestion significantly impacts travel distance, travel time, fuel consumption and air pollution. Avoidance of traffic congestion and providing drivers with optimal paths are not trivial tasks. The key contribution of this work consists of the developed approach for dynamic calculation of optimal traffic routes. Two attributes (the average travel speed of the traffic and the roads' length) are utilized by the proposed method to find the optimal paths. The average travel speed values can be obtained from the sensors deployed in smart cities and communicated to vehicles via the Internet of Vehicles and roadside communication units. The performance of the proposed algorithm is compared to three other algorithms: the simulated annealing weighted sum, the simulated annealing technique for order preference by similarity to the ideal solution and the Dijkstra algorithm. The weighted sum and technique for order preference by similarity to the ideal solution methods are used to formulate different attributes in the simulated annealing cost function. According to the Sheffield scenario, simulation results show that the improved simulated annealing technique for order preference by similarity to the ideal solution method improves the traffic performance in the presence of congestion by an overall average of 19.22% in terms of travel time, fuel consumption and CO₂ emissions as compared to other algorithms; also, similar performance patterns were achieved for the Birmingham test scenario.

  4. Automatic domain updating technique for improving computational efficiency of 2-D flood-inundation simulation

    Science.gov (United States)

    Tanaka, T.; Tachikawa, Y.; Ichikawa, Y.; Yorozu, K.

    2017-12-01

    Flood is one of the most hazardous disasters and causes serious damage to people and property around the world. To prevent/mitigate flood damage through early warning system and/or river management planning, numerical modelling of flood-inundation processes is essential. In a literature, flood-inundation models have been extensively developed and improved to achieve flood flow simulation with complex topography at high resolution. With increasing demands on flood-inundation modelling, its computational burden is now one of the key issues. Improvements of computational efficiency of full shallow water equations are made from various perspectives such as approximations of the momentum equations, parallelization technique, and coarsening approaches. To support these techniques and more improve the computational efficiency of flood-inundation simulations, this study proposes an Automatic Domain Updating (ADU) method of 2-D flood-inundation simulation. The ADU method traces the wet and dry interface and automatically updates the simulation domain in response to the progress and recession of flood propagation. The updating algorithm is as follow: first, to register the simulation cells potentially flooded at initial stage (such as floodplains nearby river channels), and then if a registered cell is flooded, to register its surrounding cells. The time for this additional process is saved by checking only cells at wet and dry interface. The computation time is reduced by skipping the processing time of non-flooded area. This algorithm is easily applied to any types of 2-D flood inundation models. The proposed ADU method is implemented to 2-D local inertial equations for the Yodo River basin, Japan. Case studies for two flood events show that the simulation is finished within two to 10 times smaller time showing the same result as that without the ADU method.

  5. Synchronization Techniques in Parallel Discrete Event Simulation

    OpenAIRE

    Lindén, Jonatan

    2018-01-01

    Discrete event simulation is an important tool for evaluating system models in many fields of science and engineering. To improve the performance of large-scale discrete event simulations, several techniques to parallelize discrete event simulation have been developed. In parallel discrete event simulation, the work of a single discrete event simulation is distributed over multiple processing elements. A key challenge in parallel discrete event simulation is to ensure that causally dependent ...

  6. Multilevel techniques for Reservoir Simulation

    DEFF Research Database (Denmark)

    Christensen, Max la Cour

    The subject of this thesis is the development, application and study of novel multilevel methods for the acceleration and improvement of reservoir simulation techniques. The motivation for addressing this topic is a need for more accurate predictions of porous media flow and the ability to carry...... Full Approximation Scheme) • Variational (Galerkin) upscaling • Linear solvers and preconditioners First, a nonlinear multigrid scheme in the form of the Full Approximation Scheme (FAS) is implemented and studied for a 3D three-phase compressible rock/fluids immiscible reservoir simulator...... is extended to include a hybrid strategy, where FAS is combined with Newton’s method to construct a multilevel nonlinear preconditioner. This method demonstrates high efficiency and robustness. Second, an improved IMPES formulated reservoir simulator is implemented using a novel variational upscaling approach...

  7. Using simulation-optimization techniques to improve multiphase aquifer remediation

    Energy Technology Data Exchange (ETDEWEB)

    Finsterle, S.; Pruess, K. [Lawrence Berkeley Laboratory, Berkeley, CA (United States)

    1995-03-01

    The T2VOC computer model for simulating the transport of organic chemical contaminants in non-isothermal multiphase systems has been coupled to the ITOUGH2 code which solves parameter optimization problems. This allows one to use linear programming and simulated annealing techniques to solve groundwater management problems, i.e. the optimization of operations for multiphase aquifer remediation. A cost function has to be defined, containing the actual and hypothetical expenses of a cleanup operation which depend - directly or indirectly - on the state variables calculated by T2VOC. Subsequently, the code iteratively determines a remediation strategy (e.g. pumping schedule) which minimizes, for instance, pumping and energy costs, the time for cleanup, and residual contamination. We discuss an illustrative sample problem to discuss potential applications of the code. The study shows that the techniques developed for estimating model parameters can be successfully applied to the solution of remediation management problems. The resulting optimum pumping scheme depends, however, on the formulation of the remediation goals and the relative weighting between individual terms of the cost function.

  8. Improving Conductivity Image Quality Using Block Matrix-based Multiple Regularization (BMMR Technique in EIT: A Simulation Study

    Directory of Open Access Journals (Sweden)

    Tushar Kanti Bera

    2011-06-01

    Full Text Available A Block Matrix based Multiple Regularization (BMMR technique is proposed for improving conductivity image quality in EIT. The response matrix (JTJ has been partitioned into several sub-block matrices and the highest eigenvalue of each sub-block matrices has been chosen as regularization parameter for the nodes contained by that sub-block. Simulated boundary data are generated for circular domain with circular inhomogeneity and the conductivity images are reconstructed in a Model Based Iterative Image Reconstruction (MoBIIR algorithm. Conductivity images are reconstructed with BMMR technique and the results are compared with the Single-step Tikhonov Regularization (STR and modified Levenberg-Marquardt Regularization (LMR methods. It is observed that the BMMR technique reduces the projection error and solution error and improves the conductivity reconstruction in EIT. Result show that the BMMR method also improves the image contrast and inhomogeneity conductivity profile and hence the reconstructed image quality is enhanced. ;doi:10.5617/jeb.170 J Electr Bioimp, vol. 2, pp. 33-47, 2011

  9. Effective colonoscopy training techniques: strategies to improve patient outcomes.

    Science.gov (United States)

    Papanikolaou, Ioannis S; Karatzas, Pantelis S; Varytimiadis, Lazaros T; Tsigaridas, Athanasios; Galanopoulos, Michail; Viazis, Nikos; Karamanolis, Dimitrios G

    2016-01-01

    Colonoscopy has substantially evolved during the last 20 years and many different training techniques have been developed in order to improve the performance of endoscopists. The most known are mechanical simulators, virtual reality simulators, computer-simulating endoscopy, magnetic endoscopic imaging, and composite and explanted animal organ simulators. Current literature generally indicates that the use of simulators improves performance of endoscopists and enhances safety of patients, especially during the initial phase of training. Moreover, newer endoscopes and imaging techniques such as high-definition colonoscopes, chromocolonoscopy with dyes spraying, and third-eye retroscope have been incorporated in everyday practice, offering better visualization of the colon and detection of polyps. Despite the abundance of these different technological features, training devices are not widely used and no official guideline or specified training algorithm or technique for lower gastrointestinal endoscopy has been evolved. In this review, we present the most important training methods currently available and evaluate these using existing literature. We also try to propose a training algorithm for novice endoscopists.

  10. An analog simulation technique for distributed flow systems

    DEFF Research Database (Denmark)

    Jørgensen, Sten Bay; Kümmel, Mogens

    1973-01-01

    earlier[3]. This is an important extension since flow systems are frequently controlled through manipulation of the flow rate. Previously the tech­nique has been applied with constant flows [4, 5]. Results demonstrating the new hardware are presented from simula­tion of a transportation lag and a double......Simulation of distributed flow systems in chemical engine­ering has been applied more and more during the last decade as computer techniques have developed [l]. The applications have served the purpose of identification of process dynamics and parameter estimation as well as improving process...... and process control design. Although the conventional analog computer has been expanded with hybrid techniques and digital simulation languages have appeared, none of these has demonstrated superiority in simulating distributed flow systems in general [l]. Conventional analog techniques are expensive...

  11. Effective colonoscopy training techniques: strategies to improve patient outcomes

    Directory of Open Access Journals (Sweden)

    Papanikolaou IS

    2016-03-01

    Full Text Available Ioannis S Papanikolaou,1 Pantelis S Karatzas,2 Lazaros T Varytimiadis,2 Athanasios Tsigaridas,2 Michail Galanopoulos,2 Nikos Viazis,2 Dimitrios G Karamanolis21Hepato-gastroenterology Unit, 2nd Department of Internal Medicine, Attikon University General Hospital, University of Athens, 2Gastroenterology Department, Evangelismos Hospital, Athens, GreeceAbstract: Colonoscopy has substantially evolved during the last 20 years and many different training techniques have been developed in order to improve the performance of endoscopists. The most known are mechanical simulators, virtual reality simulators, computer-simulating endoscopy, magnetic endoscopic imaging, and composite and explanted animal organ simulators. Current literature generally indicates that the use of simulators improves performance of endoscopists and enhances safety of patients, especially during the initial phase of training. Moreover, newer endoscopes and imaging techniques such as high-definition colonoscopes, chromocolonoscopy with dyes spraying, and third-eye retroscope have been incorporated in everyday practice, offering better visualization of the colon and detection of polyps. Despite the abundance of these different technological features, training devices are not widely used and no official guideline or specified training algorithm or technique for lower gastrointestinal endoscopy has been evolved. In this review, we present the most important training methods currently available and evaluate these using existing literature. We also try to propose a training algorithm for novice endoscopists.Keywords: endoscopy, colonoscopy, teaching techniques, simulator, endoscopists, colon, polyps

  12. A simple lightning assimilation technique for improving ...

    Science.gov (United States)

    Convective rainfall is often a large source of error in retrospective modeling applications. In particular, positive rainfall biases commonly exist during summer months due to overactive convective parameterizations. In this study, lightning assimilation was applied in the Kain-Fritsch (KF) convective scheme to improve retrospective simulations using the Weather Research and Forecasting (WRF) model. The assimilation method has a straightforward approach: force KF deep convection where lightning is observed and, optionally, suppress deep convection where lightning is absent. WRF simulations were made with and without lightning assimilation over the continental United States for July 2012, July 2013, and January 2013. The simulations were evaluated against NCEP stage-IV precipitation data and MADIS near-surface meteorological observations. In general, the use of lightning assimilation considerably improves the simulation of summertime rainfall. For example, the July 2012 monthly averaged bias of 6 h accumulated rainfall is reduced from 0.54 to 0.07 mm and the spatial correlation is increased from 0.21 to 0.43 when lightning assimilation is used. Statistical measures of near-surface meteorological variables also are improved. Consistent improvements also are seen for the July 2013 case. These results suggest that this lightning assimilation technique has the potential to substantially improve simulation of warm-season rainfall in retrospective WRF applications. The

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

    Energy Technology Data Exchange (ETDEWEB)

    Durlofsky, Louis J.

    2000-08-28

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

  14. Improving image quality in Electrical Impedance Tomography (EIT using Projection Error Propagation-based Regularization (PEPR technique: A simulation study

    Directory of Open Access Journals (Sweden)

    Tushar Kanti Bera

    2011-03-01

    Full Text Available A Projection Error Propagation-based Regularization (PEPR method is proposed and the reconstructed image quality is improved in Electrical Impedance Tomography (EIT. A projection error is produced due to the misfit of the calculated and measured data in the reconstruction process. The variation of the projection error is integrated with response matrix in each iterations and the reconstruction is carried out in EIDORS. The PEPR method is studied with the simulated boundary data for different inhomogeneity geometries. Simulated results demonstrate that the PEPR technique improves image reconstruction precision in EIDORS and hence it can be successfully implemented to increase the reconstruction accuracy in EIT.>doi:10.5617/jeb.158 J Electr Bioimp, vol. 2, pp. 2-12, 2011

  15. Improvement in visibility of simulated lung nodules on computed radiography (CR) chest images by use of temporal subtraction technique

    International Nuclear Information System (INIS)

    Oda, Nobuhiro; Fujimoto, Keiji; Murakami, Seiichi; Katsuragawa, Shigehiko; Doi, Kunio; Nakata, Hajime

    1999-01-01

    A temporal subtraction image obtained by subtraction of a previous image from a current one can enhance interval change on chest images. In this study, we compared the visibility of simulated lung nodules on CR images with and without temporal subtraction. Chest phantom images without and with simulated nodules were obtained as previous and current images, respectively, by a CR system. Then, subtraction images were produced with an iterative image warping technique. Twelve simulated nodules were attached on various locations of the chest phantom. The diameter of nodules having a CT number of 47 ranged from 3 mm to 10 mm. Seven radiologists subjectively evaluated the visibility of simulated nodules on CR images with and without temporal subtraction using a three-point rating scale (0: invisible, +1: questionable, +2:visible). The minimum diameter of simulated nodules visible at a frequency greater than 50% was 4 mm on the CR images with temporal subtraction and 6 mm on those without. Our results indicated that the subtraction images clearly improved the visibility of simulated nodules. (author)

  16. Recent developments in numerical simulation techniques of thermal recovery processes

    Energy Technology Data Exchange (ETDEWEB)

    Tamim, M. [Bangladesh University of Engineering and Technology, Bangladesh (Bangladesh); Abou-Kassem, J.H. [Chemical and Petroleum Engineering Department, UAE University, Al-Ain 17555 (United Arab Emirates); Farouq Ali, S.M. [University of Alberta, Alberta (Canada)

    2000-05-01

    Numerical simulation of thermal processes (steam flooding, steam stimulation, SAGD, in-situ combustion, electrical heating, etc.) is an integral part of a thermal project design. The general tendency in the last 10 years has been to use commercial simulators. During the last decade, only a few new models have been reported in the literature. More work has been done to modify and refine solutions to existing problems to improve the efficiency of simulators. The paper discusses some of the recent developments in simulation techniques of thermal processes such as grid refinement, grid orientation, effect of temperature on relative permeability, mathematical models, and solution methods. The various aspects of simulation discussed here promote better understanding of the problems encountered in the simulation of thermal processes and will be of value to both simulator users and developers.

  17. Testing philosophy and simulation techniques

    International Nuclear Information System (INIS)

    Holtbecker, H.

    1977-01-01

    This paper reviews past and present testing philosophies and simulation techniques in the field of structure loading and response studies. The main objective of experimental programmes in the past was to simulate a hypothetical energy release with explosives and to deduce the potential damage to a reactor from the measured damage to the model. This approach was continuously refined by improving the instrumentation of the models, by reproducing the structures as faithful as possible and by developing new explosive charges. This paper presents an analysis of the factors which are expected to have an influence on the validity of the results e.g. strain rate effects and the use of water instead of sodium. More recently the discussion of a whole series of accidents in the probabilistic accident analysis and the intention to compare different reactor designs has revealed the need to develop and validate computer codes. Consequently experimental programmes have been started in which the primary aim is not to test a specific reactor but to validate codes. This paper shows the principal aspects of this approach and discusses first results. (Auth.)

  18. Progress in the development of a video-based wind farm simulation technique

    OpenAIRE

    Robotham, AJ

    1992-01-01

    The progress in the development of a video-based wind farm simulation technique is reviewed. While improvements have been achieved in the quality of the composite picture created by combining computer generated animation sequences of wind turbines with background scenes of the wind farm site, extending the technique to include camera movements has proved troublesome.

  19. Improving Students' Speaking Ability through Scaffolding Technique

    Directory of Open Access Journals (Sweden)

    Gede Ginaya

    2018-03-01

    Full Text Available Students often got confused and felt hesitant when they speak English. This situation had caused poor speaking ability, which then lead to serious problem in the teaching-learning process.  The application of scaffolding technique in the EFL learning might be the ideal solution; it had some principles that could improve the students’ speaking ability. This research is aimed at finding out the effect of the implementing Scaffolding Technique towards the students’ speaking ability. Participants were 50 (27 males and 23 females third-semester students, enrolled in a three-year diploma program in Travel and Tourism Business, State Polytechnic of Bali in 2017/2018 academic year. The students in the experimental group were given communicative activities such as brainstorming, business games, simulation, WebQuest, problem-solving, which were carefully designed to necessitate the implementation of the scaffolding technique. The students in the control group were taught by the deductive method of the lesson book. The students’ performance in the post-test was compared for both groups in order to determine whether there were significant differences between the groups in relation to the treatment. Significant differences occurring in the experimental group’s post-test speaking performance when compared to the pre-test indicate that the implementation of scaffolding technique can improve students’ speaking ability. The result of this study indicates scaffolding technique has the potential for use in promoting students’ speaking ability

  20. Improved Nanomechanical Test Techniques for Surface Engineered Materials

    Directory of Open Access Journals (Sweden)

    Stephen R. Goodes

    2010-06-01

    Full Text Available The development and implementation of a wide range of innovative nanomechanical test techniques to solve tribological problems in applications as diverse as biomedical and automotive are described in this review. For improved wear resistance and durability, the importance of understanding the system response rather than the coating-only properties is emphasized. There are many applications involving mechanical contact where the key to understanding the problem is to test at higher load and to combine reliable measurements taken across different length scales using both nano- and micro-indentation and related wear measurement techniques which more closely simulate contact conditions to fully understand the mechanical behaviour and hence deliver improved application performance. Results are presented with the NanoTest platform for applications for biomedical devices and surface engineering of lightweight alloys for the automotive industry. By combining results with different techniques it is possible to postulate predictive design rules – based on the elastic and plastic deformation energies involved in contact - to aid the reliable optimisation of mechanical properties in the various contact situations in the different applications.

  1. Exergoeconomic improvement of a complex cogeneration system integrated with a professional process simulator

    International Nuclear Information System (INIS)

    Vieira, Leonardo S.; Donatelli, Joao L.; Cruz, Manuel E.

    2009-01-01

    In this paper, the application of an iterative exergoeconomic methodology for improvement of thermal systems to a complex combined-cycle cogeneration plant is presented. The methodology integrates exergoeconomics with a professional process simulator, and represents an alternative to conventional mathematical optimization techniques, because it reduces substantially the number of variables to be considered in the improvement process. By exploiting the computational power of a simulator, the integrated approach permits the optimization routine to ignore the variables associated with the thermodynamic equations, and thus to deal only with the economic equations and objective function. In addition, the methodology combines recent available exergoeconomic techniques with qualitative and quantitative criteria to identify only those decision variables, which matter for the improvement of the system. To demonstrate the strengths of the methodology, it is here applied to a 24-component cogeneration plant, which requires O(10 3 ) variables for its simulation. The results which are obtained, are compared to those reached using a conventional mathematical optimization procedure, also coupled to the process simulator. It is shown that, for engineering purposes, improvement of the system is often more cost effective and less time consuming than optimization of the system.

  2. Ergonomics and simulation-based approach in improving facility layout

    Science.gov (United States)

    Abad, Jocelyn D.

    2018-02-01

    The use of the simulation-based technique in facility layout has been a choice in the industry due to its convenience and efficient generation of results. Nevertheless, the solutions generated are not capable of addressing delays due to worker's health and safety which significantly impact overall operational efficiency. It is, therefore, critical to incorporate ergonomics in facility design. In this study, workstation analysis was incorporated into Promodel simulation to improve the facility layout of a garment manufacturing. To test the effectiveness of the method, existing and improved facility designs were measured using comprehensive risk level, efficiency, and productivity. Results indicated that the improved facility layout generated a decrease in comprehensive risk level and rapid upper limb assessment score; an increase of 78% in efficiency and 194% increase in productivity compared to existing design and thus proved that the approach is effective in attaining overall facility design improvement.

  3. IMPROVING BANDWIDTH OF FLIPPED VOLTAGE FOLLOWER USING GATE-BODY DRIVEN TECHNIQUE

    Directory of Open Access Journals (Sweden)

    VANDANA NIRANJAN

    2017-01-01

    Full Text Available In this paper, a new approach to enhance the bandwidth of flipped voltage follower is explored. The proposed approach is based on gate-body driven technique. This technique boosts the transconductance in a MOS transistor as both gate and body/bulk terminals are tied together and used as signal input. This novel technique appears as a good solution to merge the advantages of gate-driven and bulk-driven techniques and suppress their disadvantages. The gate-body driven technique utilizes body effect to enable low voltage low power operation and improves the overall performance of flipped voltage follower, providing it with low output impedance, high input impedance and bandwidth extension ratio of 2.614. The most attractive feature is that bandwidth enhancement has been achieved without use of any passive component or extra circuitry. Simulations in PSpice environment for 180 nm CMOS technology verified the predicted theoretical results. The improved flipped voltage follower is particularly interesting for high frequency low noise signal processing applications.

  4. Laparoscopic skill improvement after virtual reality simulator training in medical students as assessed by augmented reality simulator.

    Science.gov (United States)

    Nomura, Tsutomu; Mamada, Yasuhiro; Nakamura, Yoshiharu; Matsutani, Takeshi; Hagiwara, Nobutoshi; Fujita, Isturo; Mizuguchi, Yoshiaki; Fujikura, Terumichi; Miyashita, Masao; Uchida, Eiji

    2015-11-01

    Definitive assessment of laparoscopic skill improvement after virtual reality simulator training is best obtained during an actual operation. However, this is impossible in medical students. Therefore, we developed an alternative assessment technique using an augmented reality simulator. Nineteen medical students completed a 6-week training program using a virtual reality simulator (LapSim). The pretest and post-test were performed using an object-positioning module and cholecystectomy on an augmented reality simulator(ProMIS). The mean performance measures between pre- and post-training on the LapSim were compared with a paired t-test. In the object-positioning module, the execution time of the task (P virtual reality simulator improved the operative skills of medical students as objectively evaluated by assessment using an augmented reality simulator instead of an actual operation. We hope that these findings help to establish an effective training program for medical students. © 2015 Japan Society for Endoscopic Surgery, Asia Endosurgery Task Force and Wiley Publishing Asia Pty Ltd.

  5. Computed tomographic simulation of craniospinal fields in pediatric patients: improved treatment accuracy and patient comfort.

    Science.gov (United States)

    Mah, K; Danjoux, C E; Manship, S; Makhani, N; Cardoso, M; Sixel, K E

    1998-07-15

    To reduce the time required for planning and simulating craniospinal fields through the use of a computed tomography (CT) simulator and virtual simulation, and to improve the accuracy of field and shielding placement. A CT simulation planning technique was developed. Localization of critical anatomic features such as the eyes, cribriform plate region, and caudal extent of the thecal sac are enhanced by this technique. Over a 2-month period, nine consecutive pediatric patients were simulated and planned for craniospinal irradiation. Four patients underwent both conventional simulation and CT simulation. Five were planned using CT simulation only. The accuracy of CT simulation was assessed by comparing digitally reconstructed radiographs (DRRs) to portal films for all patients and to conventional simulation films as well in the first four patients. Time spent by patients in the CT simulation suite was 20 min on average and 40 min maximally for those who were noncompliant. Image acquisition time was absence of the patient, virtual simulation of all fields took 20 min. The DRRs were in agreement with portal and/or simulation films to within 5 mm in five of the eight cases. Discrepancies of > or =5 mm in the positioning of the inferior border of the cranial fields in the first three patients were due to a systematic error in CT scan acquisition and marker contouring which was corrected by modifying the technique after the fourth patient. In one patient, the facial shield had to be moved 0.75 cm inferiorly owing to an error in shield construction. Our analysis showed that CT simulation of craniospinal fields was accurate. It resulted in a significant reduction in the time the patient must be immobilized during the planning process. This technique can improve accuracy in field placement and shielding by using three-dimensional CT-aided localization of critical and target structures. Overall, it has improved staff efficiency and resource utilization.

  6. Computed tomographic simulation of craniospinal fields in pediatric patients: improved treatment accuracy and patient comfort

    International Nuclear Information System (INIS)

    Mah, Katherine; Danjoux, Cyril E.; Manship, Sharan; Makhani, Nadiya; Cardoso, Marlene; Sixel, Katharina E.

    1998-01-01

    Purpose: To reduce the time required for planning and simulating craniospinal fields through the use of a computed tomography (CT) simulator and virtual simulation, and to improve the accuracy of field and shielding placement. Methods and Materials: A CT simulation planning technique was developed. Localization of critical anatomic features such as the eyes, cribriform plate region, and caudal extent of the thecal sac are enhanced by this technique. Over a 2-month period, nine consecutive pediatric patients were simulated and planned for craniospinal irradiation. Four patients underwent both conventional simulation and CT simulation. Five were planned using CT simulation only. The accuracy of CT simulation was assessed by comparing digitally reconstructed radiographs (DRRs) to portal films for all patients and to conventional simulation films as well in the first four patients. Results: Time spent by patients in the CT simulation suite was 20 min on average and 40 min maximally for those who were noncompliant. Image acquisition time was <10 min in all cases. In the absence of the patient, virtual simulation of all fields took 20 min. The DRRs were in agreement with portal and/or simulation films to within 5 mm in five of the eight cases. Discrepancies of ≥5 mm in the positioning of the inferior border of the cranial fields in the first three patients were due to a systematic error in CT scan acquisition and marker contouring which was corrected by modifying the technique after the fourth patient. In one patient, the facial shield had to be moved 0.75 cm inferiorly owing to an error in shield construction. Conclusions: Our analysis showed that CT simulation of craniospinal fields was accurate. It resulted in a significant reduction in the time the patient must be immobilized during the planning process. This technique can improve accuracy in field placement and shielding by using three-dimensional CT-aided localization of critical and target structures. Overall

  7. A Comparative Analysis of Transmission Control Protocol Improvement Techniques over Space-Based Transmission Media

    National Research Council Canada - National Science Library

    Lawson, Joseph M

    2006-01-01

    The purpose of this study was to assess the throughput improvement afforded by the various TCP optimization techniques, with respect to a simulated geosynchronous satellite system, to provide a cost...

  8. Physical simulations using centrifuge techniques

    International Nuclear Information System (INIS)

    Sutherland, H.J.

    1981-01-01

    Centrifuge techniques offer a technique for doing physical simulations of the long-term mechanical response of deep ocean sediment to the emplacement of waste canisters and to the temperature gradients generated by them. Preliminary investigations of the scaling laws for pertinent phenomena indicate that the time scaling will be consistent among them and equal to the scaling factor squared. This result implies that this technique will permit accelerated-life-testing of proposed configurations; i.e, long-term studies may be done in relatively short times. Presently, existing centrifuges are being modified to permit scale model testing. This testing will start next year

  9. Model extension and improvement for simulator-based software safety analysis

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.-W. [Department of Engineering and System Science, National Tsing Hua University (NTHU), 101 Section 2 Kuang Fu Road, Hsinchu, Taiwan (China) and Institute of Nuclear Energy Research (INER), No. 1000 Wenhua Road, Chiaan Village, Longtan Township, Taoyuan County 32546, Taiwan (China)]. E-mail: hwhwang@iner.gov.tw; Shih Chunkuan [Department of Engineering and System Science, National Tsing Hua University (NTHU), 101 Section 2 Kuang Fu Road, Hsinchu, Taiwan (China); Yih Swu [Department of Computer Science and Information Engineering, Ching Yun University, 229 Chien-Hsin Road, Jung-Li, Taoyuan County 320, Taiwan (China); Chen, M.-H. [Institute of Nuclear Energy Research (INER), No. 1000Wenhua Road, Chiaan Village, Longtan Township, Taoyuan County 32546, Taiwan (China); Lin, J.-M. [Taiwan Power Company (TPC), 242 Roosevelt Road, Section 3, Taipei 100, Taiwan (China)

    2007-05-15

    One of the major concerns when employing digital I and C system in nuclear power plant is digital system may introduce new failure mode, which differs with previous analog I and C system. Various techniques are under developing to analyze the hazard originated from software faults in digital systems. Preliminary hazard analysis, failure modes and effects analysis, and fault tree analysis are the most extensive used techniques. However, these techniques are static analysis methods, cannot perform dynamic analysis and the interactions among systems. This research utilizes 'simulator/plant model testing' technique classified in (IEEE Std 7-4.3.2-2003, 2003. IEEE Standard for Digital Computers in Safety Systems of Nuclear Power Generating Stations) to identify hazards which might be induced by nuclear I and C software defects. The recirculation flow system, control rod system, feedwater system, steam line model, dynamic power-core flow map, and related control systems of PCTran-ABWR model were successfully extended and improved. The benchmark against ABWR SAR proves this modified model is capable to accomplish dynamic system level software safety analysis and better than the static methods. This improved plant simulation can then further be applied to hazard analysis for operator/digital I and C interface interaction failure study, and the hardware-in-the-loop fault injection study.

  10. ADVANCED TECHNIQUES FOR RESERVOIR SIMULATION AND MODELING OF NONCONVENTIONAL WELLS

    Energy Technology Data Exchange (ETDEWEB)

    Louis J. Durlofsky; Khalid Aziz

    2004-08-20

    Nonconventional wells, which include horizontal, deviated, multilateral and ''smart'' wells, offer great potential for the efficient management of oil and gas reservoirs. These wells are able to contact larger regions of the reservoir than conventional wells and can also be used to target isolated hydrocarbon accumulations. The use of nonconventional wells instrumented with downhole inflow control devices allows for even greater flexibility in production. Because nonconventional wells can be very expensive to drill, complete and instrument, it is important to be able to optimize their deployment, which requires the accurate prediction of their performance. However, predictions of nonconventional well performance are often inaccurate. This is likely due to inadequacies in some of the reservoir engineering and reservoir simulation tools used to model and optimize nonconventional well performance. A number of new issues arise in the modeling and optimization of nonconventional wells. For example, the optimal use of downhole inflow control devices has not been addressed for practical problems. In addition, the impact of geological and engineering uncertainty (e.g., valve reliability) has not been previously considered. In order to model and optimize nonconventional wells in different settings, it is essential that the tools be implemented into a general reservoir simulator. This simulator must be sufficiently general and robust and must in addition be linked to a sophisticated well model. Our research under this five year project addressed all of the key areas indicated above. The overall project was divided into three main categories: (1) advanced reservoir simulation techniques for modeling nonconventional wells; (2) improved techniques for computing well productivity (for use in reservoir engineering calculations) and for coupling the well to the simulator (which includes the accurate calculation of well index and the modeling of multiphase flow

  11. eLearning techniques supporting problem based learning in clinical simulation.

    Science.gov (United States)

    Docherty, Charles; Hoy, Derek; Topp, Helena; Trinder, Kathryn

    2005-08-01

    This paper details the results of the first phase of a project using eLearning to support students' learning within a simulated environment. The locus was a purpose built clinical simulation laboratory (CSL) where the School's philosophy of problem based learning (PBL) was challenged through lecturers using traditional teaching methods. a student-centred, problem based approach to the acquisition of clinical skills that used high quality learning objects embedded within web pages, substituting for lecturers providing instruction and demonstration. This encouraged student nurses to explore, analyse and make decisions within the safety of a clinical simulation. Learning was facilitated through network communications and reflection on video performances of self and others. Evaluations were positive, students demonstrating increased satisfaction with PBL, improved performance in exams, and increased self-efficacy in the performance of nursing activities. These results indicate that eLearning techniques can help students acquire clinical skills in the safety of a simulated environment within the context of a problem based learning curriculum.

  12. Design Techniques and Reservoir Simulation

    Directory of Open Access Journals (Sweden)

    Ahad Fereidooni

    2012-11-01

    Full Text Available Enhanced oil recovery using nitrogen injection is a commonly applied method for pressure maintenance in conventional reservoirs. Numerical simulations can be practiced for the prediction of a reservoir performance in the course of injection process; however, a detailed simulation might take up enormous computer processing time. In such cases, a simple statistical model may be a good approach to the preliminary prediction of the process without any application of numerical simulation. In the current work, seven rock/fluid reservoir properties are considered as screening parameters and those parameters having the most considerable effect on the process are determined using the combination of experimental design techniques and reservoir simulations. Therefore, the statistical significance of the main effects and interactions of screening parameters are analyzed utilizing statistical inference approaches. Finally, the influential parameters are employed to create a simple statistical model which allows the preliminary prediction of nitrogen injection in terms of a recovery factor without resorting to numerical simulations.

  13. A New Simulation Technique for Study of Collisionless Shocks: Self-Adaptive Simulations

    International Nuclear Information System (INIS)

    Karimabadi, H.; Omelchenko, Y.; Driscoll, J.; Krauss-Varban, D.; Fujimoto, R.; Perumalla, K.

    2005-01-01

    The traditional technique for simulating physical systems modeled by partial differential equations is by means of time-stepping methodology where the state of the system is updated at regular discrete time intervals. This method has inherent inefficiencies. In contrast to this methodology, we have developed a new asynchronous type of simulation based on a discrete-event-driven (as opposed to time-driven) approach, where the simulation state is updated on a 'need-to-be-done-only' basis. Here we report on this new technique, show an example of particle acceleration in a fast magnetosonic shockwave, and briefly discuss additional issues that we are addressing concerning algorithm development and parallel execution

  14. CT simulation technique for craniospinal irradiation in supine position

    International Nuclear Information System (INIS)

    Lee, Suk; Kim, Yong Bae; Chu, Sung Sil; Suh, Chang Ok; Kwon, Soo Il

    2002-01-01

    In order to perform craniospinal irradiation (CSI) in the supine position on patients who are unable to lie in the prone position, a new simulation technique using a CT simulator was developed and its availability was evaluated. A CT simulator and a 3-D conformal treatment planning system were used to develop CSI in the supine position. The head and neck were immobilized with a thermoplastic mask in the supine position and the entire body was immobilized with a Vac-Loc. A volumetric image was then obtained using the CT simulator. In order to improve the reproducibility of the patients' setup, datum lines and points were marked on the head and the body. Virtual fluoroscopy was performed with the removal of visual obstacles such as the treatment table or the immobilization devices. After the virtual simulation, the treatment isocenters of each field were marked on the body and the immobilization devices at the conventional simulation room. Each treatment field was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR)/digitally composite radiography (DCR) images from the virtual simulation. The port verification films from the first treatment were also compared with the DRR/DCR images for a geometrical verification. CSI in the supine position was successfully performed in 9 patients. It required less than 20 minutes to construct the immobilization device and to obtain the whole body volumetric images. This made it possible to not only reduce the patients' inconvenience, but also to eliminate the position change variables during the long conventional simulation process. In addition, by obtaining the CT volumetric image, critical organs, such as the eyeballs and spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. The difference between the DRRs and the portal films were less than 3 mm in the vertebral contour. CSI in the supine position is feasible in patients who cannot lie on

  15. CT simulation technique for craniospinal irradiation in supine position

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Suk; Kim, Yong Bae; Chu, Sung Sil; Suh, Chang Ok [Yonsei Cancer Center, College of Medicine, Yonsei University, Seoul (Korea, Republic of); Kwon, Soo Il [Kyonggi University, Seoul (Korea, Republic of)

    2002-06-15

    In order to perform craniospinal irradiation (CSI) in the supine position on patients who are unable to lie in the prone position, a new simulation technique using a CT simulator was developed and its availability was evaluated. A CT simulator and a 3-D conformal treatment planning system were used to develop CSI in the supine position. The head and neck were immobilized with a thermoplastic mask in the supine position and the entire body was immobilized with a Vac-Loc. A volumetric image was then obtained using the CT simulator. In order to improve the reproducibility of the patients' setup, datum lines and points were marked on the head and the body. Virtual fluoroscopy was performed with the removal of visual obstacles such as the treatment table or the immobilization devices. After the virtual simulation, the treatment isocenters of each field were marked on the body and the immobilization devices at the conventional simulation room. Each treatment field was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR)/digitally composite radiography (DCR) images from the virtual simulation. The port verification films from the first treatment were also compared with the DRR/DCR images for a geometrical verification. CSI in the supine position was successfully performed in 9 patients. It required less than 20 minutes to construct the immobilization device and to obtain the whole body volumetric images. This made it possible to not only reduce the patients' inconvenience, but also to eliminate the position change variables during the long conventional simulation process. In addition, by obtaining the CT volumetric image, critical organs, such as the eyeballs and spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. The difference between the DRRs and the portal films were less than 3 mm in the vertebral contour. CSI in the supine position is feasible in patients who cannot

  16. Parallel pic plasma simulation through particle decomposition techniques

    International Nuclear Information System (INIS)

    Briguglio, S.; Vlad, G.; Di Martino, B.; Naples, Univ. 'Federico II'

    1998-02-01

    Particle-in-cell (PIC) codes are among the major candidates to yield a satisfactory description of the detail of kinetic effects, such as the resonant wave-particle interaction, relevant in determining the transport mechanism in magnetically confined plasmas. A significant improvement of the simulation performance of such codes con be expected from parallelization, e.g., by distributing the particle population among several parallel processors. Parallelization of a hybrid magnetohydrodynamic-gyrokinetic code has been accomplished within the High Performance Fortran (HPF) framework, and tested on the IBM SP2 parallel system, using a 'particle decomposition' technique. The adopted technique requires a moderate effort in porting the code in parallel form and results in intrinsic load balancing and modest inter processor communication. The performance tests obtained confirm the hypothesis of high effectiveness of the strategy, if targeted towards moderately parallel architectures. Optimal use of resources is also discussed with reference to a specific physics problem [it

  17. Low-mass molecular dynamics simulation: A simple and generic technique to enhance configurational sampling

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Yuan-Ping, E-mail: pang@mayo.edu

    2014-09-26

    Highlights: • Reducing atomic masses by 10-fold vastly improves sampling in MD simulations. • CLN025 folded in 4 of 10 × 0.5-μs MD simulations when masses were reduced by 10-fold. • CLN025 folded as early as 96.2 ns in 1 of the 4 simulations that captured folding. • CLN025 did not fold in 10 × 0.5-μs MD simulations when standard masses were used. • Low-mass MD simulation is a simple and generic sampling enhancement technique. - Abstract: CLN025 is one of the smallest fast-folding proteins. Until now it has not been reported that CLN025 can autonomously fold to its native conformation in a classical, all-atom, and isothermal–isobaric molecular dynamics (MD) simulation. This article reports the autonomous and repeated folding of CLN025 from a fully extended backbone conformation to its native conformation in explicit solvent in multiple 500-ns MD simulations at 277 K and 1 atm with the first folding event occurring as early as 66.1 ns. These simulations were accomplished by using AMBER forcefield derivatives with atomic masses reduced by 10-fold on Apple Mac Pros. By contrast, no folding event was observed when the simulations were repeated using the original AMBER forcefields of FF12SB and FF14SB. The results demonstrate that low-mass MD simulation is a simple and generic technique to enhance configurational sampling. This technique may propel autonomous folding of a wide range of miniature proteins in classical, all-atom, and isothermal–isobaric MD simulations performed on commodity computers—an important step forward in quantitative biology.

  18. Five Topics Health Care Simulation Can Address to Improve Patient Safety

    DEFF Research Database (Denmark)

    Sollid, Stephen J M; Dieckman, Peter; Aase, Karina

    2017-01-01

    OBJECTIVES: There is little knowledge about which elements of health care simulation are most effective in improving patient safety. When empirical evidence is lacking, a consensus statement can help define priorities in, for example, education and research. A consensus process was therefore...... initiated to define priorities in health care simulation that contribute the most to improve patient safety.  METHODS: An international group of experts took part in a 4-stage consensus process based on a modified nominal group technique. Stages 1 to 3 were based on electronic communication; stage 4 was a 2......-day consensus meeting at the Utstein Abbey in Norway. The goals of stage 4 were to agree on the top 5 topics in health care simulation that contribute the most to patient safety, identify the patient safety problems they relate to, and suggest solutions with implementation strategies...

  19. Transient Stability Improvement of IEEE 9 Bus System Using Power World Simulator

    Directory of Open Access Journals (Sweden)

    Kaur Ramandeep

    2016-01-01

    Full Text Available The improvement of transient stability of power system was one of the most challenging research areas in power engineer.The main aim of this paper was transient stability analysis and improvement of IEEE 9 bus system. These studies were computed using POWER WORLD SIMULATOR. The IEEE 9 bus system was modelled in power world simulator and load flow studies were performed to determine pre-fault conditions in the system using Newton-Raphson method. The transient stability analysis was carried out using Runga method during three-phase balanced fault. For the improvement transient stability, the general methods adopted were fast acting exciters, FACT devices and addition of parallel transmission line. These techniques play an important role in improving the transient stability, increasing transmission capacity and damping low frequency oscillations.

  20. Simulation-based optimization parametric optimization techniques and reinforcement learning

    CERN Document Server

    Gosavi, Abhijit

    2003-01-01

    Simulation-Based Optimization: Parametric Optimization Techniques and Reinforcement Learning introduces the evolving area of simulation-based optimization. The book's objective is two-fold: (1) It examines the mathematical governing principles of simulation-based optimization, thereby providing the reader with the ability to model relevant real-life problems using these techniques. (2) It outlines the computational technology underlying these methods. Taken together these two aspects demonstrate that the mathematical and computational methods discussed in this book do work. Broadly speaking, the book has two parts: (1) parametric (static) optimization and (2) control (dynamic) optimization. Some of the book's special features are: *An accessible introduction to reinforcement learning and parametric-optimization techniques. *A step-by-step description of several algorithms of simulation-based optimization. *A clear and simple introduction to the methodology of neural networks. *A gentle introduction to converg...

  1. Improved Titanium Billet Inspection Sensitivity through Optimized Phased Array Design, Part I: Design Technique, Modeling and Simulation

    International Nuclear Information System (INIS)

    Lupien, Vincent; Hassan, Waled; Dumas, Philippe

    2006-01-01

    Reductions in the beam diameter and pulse duration of focused ultrasound for titanium inspections are believed to result in a signal-to-noise ratio improvement for embedded defect detection. It has been inferred from this result that detection limits could be extended to smaller defects through a larger diameter, higher frequency transducer resulting in a reduced beamwidth and pulse duration. Using Continuum Probe Designer TM (Pat. Pending), a transducer array was developed for full coverage inspection of 8 inch titanium billets. The main challenge in realizing a large aperture phased array transducer for billet inspection is ensuring that the number of elements remains within the budget allotted by the driving electronics. The optimization technique implemented by Continuum Probe Designer TM yields an array with twice the aperture but the same number of elements as existing phased arrays for the same application. The unequal area element design was successfully manufactured and validated both numerically and experimentally. Part I of this two-part series presents the design, simulation and modeling steps, while Part II presents the experimental validation and comparative study to multizone

  2. The use of discrete-event simulation modelling to improve radiation therapy planning processes.

    Science.gov (United States)

    Werker, Greg; Sauré, Antoine; French, John; Shechter, Steven

    2009-07-01

    The planning portion of the radiation therapy treatment process at the British Columbia Cancer Agency is efficient but nevertheless contains room for improvement. The purpose of this study is to show how a discrete-event simulation (DES) model can be used to represent this complex process and to suggest improvements that may reduce the planning time and ultimately reduce overall waiting times. A simulation model of the radiation therapy (RT) planning process was constructed using the Arena simulation software, representing the complexities of the system. Several types of inputs feed into the model; these inputs come from historical data, a staff survey, and interviews with planners. The simulation model was validated against historical data and then used to test various scenarios to identify and quantify potential improvements to the RT planning process. Simulation modelling is an attractive tool for describing complex systems, and can be used to identify improvements to the processes involved. It is possible to use this technique in the area of radiation therapy planning with the intent of reducing process times and subsequent delays for patient treatment. In this particular system, reducing the variability and length of oncologist-related delays contributes most to improving the planning time.

  3. CASTING IMPROVEMENT BASED ON METAHEURISTIC OPTIMIZATION AND NUMERICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    Radomir Radiša

    2017-12-01

    Full Text Available This paper presents the use of metaheuristic optimization techniques to support the improvement of casting process. Genetic algorithm (GA, Ant Colony Optimization (ACO, Simulated annealing (SA and Particle Swarm Optimization (PSO have been considered as optimization tools to define the geometry of the casting part’s feeder. The proposed methodology has been demonstrated in the design of the feeder for casting Pelton turbine bucket. The results of the optimization are dimensional characteristics of the feeder, and the best result from all the implemented optimization processes has been adopted. Numerical simulation has been used to verify the validity of the presented design methodology and the feeding system optimization in the casting system of the Pelton turbine bucket.

  4. Development of a technique for inflight jet noise simulation. I, II

    Science.gov (United States)

    Clapper, W. S.; Stringas, E. J.; Mani, R.; Banerian, G.

    1976-01-01

    Several possible noise simulation techniques were evaluated, including closed circuit wind tunnels, free jets, rocket sleds and high speed trains. The free jet technique was selected for demonstration and verification. The first paper describes the selection and development of the technique and presents results for simulation and in-flight tests of the Learjet, F106, and Bertin Aerotrain. The second presents a theoretical study relating the two sets of noise signatures. It is concluded that the free jet simulation technique provides a satisfactory assessment of in-flight noise.

  5. Numerical techniques for large cosmological N-body simulations

    International Nuclear Information System (INIS)

    Efstathiou, G.; Davis, M.; Frenk, C.S.; White, S.D.M.

    1985-01-01

    We describe and compare techniques for carrying out large N-body simulations of the gravitational evolution of clustering in the fundamental cube of an infinite periodic universe. In particular, we consider both particle mesh (PM) codes and P 3 M codes in which a higher resolution force is obtained by direct summation of contributions from neighboring particles. We discuss the mesh-induced anisotropies in the forces calculated by these schemes, and the extent to which they can model the desired 1/r 2 particle-particle interaction. We also consider how transformation of the time variable can improve the efficiency with which the equations of motion are integrated. We present tests of the accuracy with which the resulting schemes conserve energy and are able to follow individual particle trajectories. We have implemented an algorithm which allows initial conditions to be set up to model any desired spectrum of linear growing mode density fluctuations. A number of tests demonstrate the power of this algorithm and delineate the conditions under which it is effective. We carry out several test simulations using a variety of techniques in order to show how the results are affected by dynamic range limitations in the force calculations, by boundary effects, by residual artificialities in the initial conditions, and by the number of particles employed. For most purposes cosmological simulations are limited by the resolution of their force calculation rather than by the number of particles they can employ. For this reason, while PM codes are quite adequate to study the evolution of structure on large scale, P 3 M methods are to be preferred, in spite of their greater cost and complexity, whenever the evolution of small-scale structure is important

  6. A fast simulation method for the Log-normal sum distribution using a hazard rate twisting technique

    KAUST Repository

    Rached, Nadhir B.

    2015-06-08

    The probability density function of the sum of Log-normally distributed random variables (RVs) is a well-known challenging problem. For instance, an analytical closed-form expression of the Log-normal sum distribution does not exist and is still an open problem. A crude Monte Carlo (MC) simulation is of course an alternative approach. However, this technique is computationally expensive especially when dealing with rare events (i.e. events with very small probabilities). Importance Sampling (IS) is a method that improves the computational efficiency of MC simulations. In this paper, we develop an efficient IS method for the estimation of the Complementary Cumulative Distribution Function (CCDF) of the sum of independent and not identically distributed Log-normal RVs. This technique is based on constructing a sampling distribution via twisting the hazard rate of the original probability measure. Our main result is that the estimation of the CCDF is asymptotically optimal using the proposed IS hazard rate twisting technique. We also offer some selected simulation results illustrating the considerable computational gain of the IS method compared to the naive MC simulation approach.

  7. A fast simulation method for the Log-normal sum distribution using a hazard rate twisting technique

    KAUST Repository

    Rached, Nadhir B.; Benkhelifa, Fatma; Alouini, Mohamed-Slim; Tempone, Raul

    2015-01-01

    The probability density function of the sum of Log-normally distributed random variables (RVs) is a well-known challenging problem. For instance, an analytical closed-form expression of the Log-normal sum distribution does not exist and is still an open problem. A crude Monte Carlo (MC) simulation is of course an alternative approach. However, this technique is computationally expensive especially when dealing with rare events (i.e. events with very small probabilities). Importance Sampling (IS) is a method that improves the computational efficiency of MC simulations. In this paper, we develop an efficient IS method for the estimation of the Complementary Cumulative Distribution Function (CCDF) of the sum of independent and not identically distributed Log-normal RVs. This technique is based on constructing a sampling distribution via twisting the hazard rate of the original probability measure. Our main result is that the estimation of the CCDF is asymptotically optimal using the proposed IS hazard rate twisting technique. We also offer some selected simulation results illustrating the considerable computational gain of the IS method compared to the naive MC simulation approach.

  8. Improving Simulated Annealing by Replacing Its Variables with Game-Theoretic Utility Maximizers

    Science.gov (United States)

    Wolpert, David H.; Bandari, Esfandiar; Tumer, Kagan

    2001-01-01

    The game-theory field of Collective INtelligence (COIN) concerns the design of computer-based players engaged in a non-cooperative game so that as those players pursue their self-interests, a pre-specified global goal for the collective computational system is achieved as a side-effect. Previous implementations of COIN algorithms have outperformed conventional techniques by up to several orders of magnitude, on domains ranging from telecommunications control to optimization in congestion problems. Recent mathematical developments have revealed that these previously developed algorithms were based on only two of the three factors determining performance. Consideration of only the third factor would instead lead to conventional optimization techniques like simulated annealing that have little to do with non-cooperative games. In this paper we present an algorithm based on all three terms at once. This algorithm can be viewed as a way to modify simulated annealing by recasting it as a non-cooperative game, with each variable replaced by a player. This recasting allows us to leverage the intelligent behavior of the individual players to substantially improve the exploration step of the simulated annealing. Experiments are presented demonstrating that this recasting significantly improves simulated annealing for a model of an economic process run over an underlying small-worlds topology. Furthermore, these experiments reveal novel small-worlds phenomena, and highlight the shortcomings of conventional mechanism design in bounded rationality domains.

  9. Application perspectives of simulation techniques CFD in nuclear power plants

    International Nuclear Information System (INIS)

    Galindo G, I. F.

    2013-10-01

    The scenarios simulation in nuclear power plants is usually carried out with system codes that are based on concentrated parameters networks. However situations exist in some components where the flow is predominantly 3-D, as they are the natural circulation, mixed and stratification phenomena. The simulation techniques of computational fluid dynamics (CFD) have the potential to simulate these flows numerically. The use of CFD simulations embraces many branches of the engineering and continues growing, however, in relation to its application with respect to the problems related with the safety in nuclear power plants, has a smaller development, although is accelerating quickly and is expected that in the future they play a more emphasized paper in the analyses. A main obstacle to be able to achieve a general acceptance of the CFD is that the simulations should have very complete validation studies, sometimes not available. In this article a general panorama of the state of the methods application CFD in nuclear power plants is presented and the problem associated to its routine application and acceptance, including the view point of the regulatory authorities. Application examples are revised in those that the CFD offers real benefits and are also presented two illustrative study cases of the application of CFD techniques. The case of a water recipient with a heat source in its interior, similar to spent fuel pool of a nuclear power plant is presented firstly; and later the case of the Boron dilution of a water volume that enters to a nuclear reactor is presented. We can conclude that the CFD technology represents a very important opportunity to improve the phenomena understanding with a strong component 3-D and to contribute in the uncertainty reduction. (Author)

  10. Acceleration techniques for dependability simulation. M.S. Thesis

    Science.gov (United States)

    Barnette, James David

    1995-01-01

    As computer systems increase in complexity, the need to project system performance from the earliest design and development stages increases. We have to employ simulation for detailed dependability studies of large systems. However, as the complexity of the simulation model increases, the time required to obtain statistically significant results also increases. This paper discusses an approach that is application independent and can be readily applied to any process-based simulation model. Topics include background on classical discrete event simulation and techniques for random variate generation and statistics gathering to support simulation.

  11. [Preparation of simulate craniocerebral models via three dimensional printing technique].

    Science.gov (United States)

    Lan, Q; Chen, A L; Zhang, T; Zhu, Q; Xu, T

    2016-08-09

    Three dimensional (3D) printing technique was used to prepare the simulate craniocerebral models, which were applied to preoperative planning and surgical simulation. The image data was collected from PACS system. Image data of skull bone, brain tissue and tumors, cerebral arteries and aneurysms, and functional regions and relative neural tracts of the brain were extracted from thin slice scan (slice thickness 0.5 mm) of computed tomography (CT), magnetic resonance imaging (MRI, slice thickness 1mm), computed tomography angiography (CTA), and functional magnetic resonance imaging (fMRI) data, respectively. MIMICS software was applied to reconstruct colored virtual models by identifying and differentiating tissues according to their gray scales. Then the colored virtual models were submitted to 3D printer which produced life-sized craniocerebral models for surgical planning and surgical simulation. 3D printing craniocerebral models allowed neurosurgeons to perform complex procedures in specific clinical cases though detailed surgical planning. It offered great convenience for evaluating the size of spatial fissure of sellar region before surgery, which helped to optimize surgical approach planning. These 3D models also provided detailed information about the location of aneurysms and their parent arteries, which helped surgeons to choose appropriate aneurismal clips, as well as perform surgical simulation. The models further gave clear indications of depth and extent of tumors and their relationship to eloquent cortical areas and adjacent neural tracts, which were able to avoid surgical damaging of important neural structures. As a novel and promising technique, the application of 3D printing craniocerebral models could improve the surgical planning by converting virtual visualization into real life-sized models.It also contributes to functional anatomy study.

  12. A Dynamic Operation Permission Technique Based on an MFM Model and Numerical Simulation

    International Nuclear Information System (INIS)

    Akio, Gofuku; Masahiro, Yonemura

    2011-01-01

    It is important to support operator activities to an abnormal plant situation where many counter actions are taken in relatively short time. The authors proposed a technique called dynamic operation permission to decrease human errors without eliminating creative idea of operators to cope with an abnormal plant situation by checking if the counter action taken is consistent with emergency operation procedure. If the counter action is inconsistent, a dynamic operation permission system warns it to operators. It also explains how and why the counter action is inconsistent and what influence will appear on the future plant behavior by a qualitative influence inference technique based on a model by the Mf (Multilevel Flow Modeling). However, the previous dynamic operation permission is not able to explain quantitative effects on plant future behavior. Moreover, many possible influence paths are derived because a qualitative reasoning does not give a solution when positive and negative influences are propagated to the same node. This study extends the dynamic operation permission by combining the qualitative reasoning and the numerical simulation technique. The qualitative reasoning based on an Mf model of plant derives all possible influence propagation paths. Then, a numerical simulation gives a prediction of plant future behavior in the case of taking a counter action. The influence propagation that does not coincide with the simulation results is excluded from possible influence paths. The extended technique is implemented in a dynamic operation permission system for an oil refinery plant. An MFM model and a static numerical simulator are developed. The results of dynamic operation permission for some abnormal plant situations show the improvement of the accuracy of dynamic operation permission and the quality of explanation for the effects of the counter action taken

  13. Lidar signal-to-noise ratio improvements: Considerations and techniques

    Science.gov (United States)

    Hassebo, Yasser Y.

    The primary objective of this study is to improve lidar signal-to-noise ratio (SNR) and hence extend attainable lidar ranges through reduction of the sky background noise (BGP), which dominates other sources of noise in daytime operations. This is particularly important for Raman lidar techniques where the Raman backscattered signal of interest is relatively weak compared with the elastic backscatter lidars. Two approaches for reduction of sky background noise are considered: (1) Improvements in lidar SNR by optimization of the design of the lidar receiver were examined by a series of simulations. This part of the research concentrated on biaxial lidar systems, where overlap between laser beam and receiver field of view (FOV) is an important aspect of noise considerations. The first optimized design evolved is a wedge shaped aperture. While this design has the virtue of greatly reducing background light, it is difficult to implement practically, requiring both changes in area and position with lidar range. A second more practical approach, which preserves some of the advantages of the wedge design, was also evolved. This uses a smaller area circular aperture optimally located in the image plane for desired ranges. Simulated numerical results for a biaxial lidar have shown that the best receiver parameters selection is one using a small circular aperture (field stop) with a small telescope focal length f, to ensure the minimum FOV that accepts all return signals over the entire lidar range while at the same time minimizing detected BGP and hence maximizing lidar SNR and attainable lidar ranges. The improvement in lidar SNR was up to 18%. (2) A polarization selection technique was implemented to reduce sky background signal for linearly polarized monostatic elastic backscatter lidar measurements. The technique takes advantage of naturally occurring polarization properties in scattered sky light, and then ensures that both the lidar transmitter and receiver track and

  14. An improved technique for fission track dating

    International Nuclear Information System (INIS)

    Zhao Yunlong; Wu Zhaohui; Xia Yuliang

    1996-01-01

    The necessity of improving the fission track dating (FTD) technique both at home and abroad is illustrated. The ways of making such improvement are also proposed. It is suggested to calibrate the constant b value of the uranium standard glass by using the method of fission products activity. The 3 kinds of uranium standard glass which have been calibrated are NBS SRM962a, UB 1 and UB 2 . An established new method σ·Φ ρ d /b, to measure neutron fluence, avoids the influence of the varying neutron spectrum on measuring neutron fluence. The improved etching technique for fission tracks in zircon adopted a two-step method which includes the molten alkali system etching using NaOH + KOH and the mixed acid system etching using HNO 3 + HF; this technique results in adequate track etching, increased track clarity and less interference. In this way the intensity of tracks is authentically reflected. Dividing angular zone in accordance with the angular distribution of spontaneous fission track on the crystal surface of minerals to count the tracks and using the improved etching technique to remove the non-uniform angular distribution of spontaneous fission tracks in zircon, ensure the accuracy of tracks count. The improved FTD techniques were used to finish Laboratory Standardized Calibration. The tests using international FTD age standards samples have proved that above mentioned techniques are reliable and practical in obtaining the accurate FTD data. (8 tabs.; 3 figs.)

  15. Three-dimensional Improved Delayed Detached Eddy Simulation of a two-bladed vertical axis wind turbine

    International Nuclear Information System (INIS)

    Lei, Hang; Zhou, Dai; Bao, Yan; Li, Ye; Han, Zhaolong

    2017-01-01

    Highlights: • The Improved Delayed Detached Eddy Simulation and polyhedral mesh are utilized. • Power coefficient and wake velocity are compared between experiments and simulations. • Improved Delayed Detached Eddy Simulation shows more vortices under dynamic stall. • Different scales of flow separations are distinguished by these two models. - Abstract: The aerodynamic performance of a two-bladed vertical axis wind turbine is investigated using the turbulence model of the Improved Delayed Detached Eddy Simulation and the polyhedral mesh. The sliding mesh technique is used to simulate the rotation of the rotor. Meanwhile, the results obtained by the shear stress transport k-ω model are presented as contrast. Then, the simulated power coefficients at different tip speed ratios and the wake velocity are validated by comparison with the experimental data from available literature. It is shown that the power coefficients and wake velocity predicted by the Improved Delayed Detached Eddy Simulation are closer to the experimental data than those by the shear stress transport k-ω model. The pressure distributions predicted by the two turbulence models show different degrees of discrepancies in different scales of flow separation. By comparing the vorticity magnitude graphs, the Improved Delayed Detached Eddy Simulation is found to be able to capture more exquisite vortices after the flow separations. Limited by its inherent ability, the shear stress transport k-ω model predicts vortices that are less realistic than those of Improved Delayed Detached Eddy Simulation. Hence, it may cause some errors in predicting the pressure distributions, especially when the blades suffer dynamic stall. It is demonstrated that the Improved Delayed Detached Eddy Simulation is regarded as a reliable model to analyze the aerodynamic performance of vertical axis wine turbines.

  16. Visual air quality simulation techniques

    Science.gov (United States)

    Molenar, John V.; Malm, William C.; Johnson, Christopher E.

    Visual air quality is primarily a human perceptual phenomenon beginning with the transfer of image-forming information through an illuminated, scattering and absorbing atmosphere. Visibility, especially the visual appearance of industrial emissions or the degradation of a scenic view, is the principal atmospheric characteristic through which humans perceive air pollution, and is more sensitive to changing pollution levels than any other air pollution effect. Every attempt to quantify economic costs and benefits of air pollution has indicated that good visibility is a highly valued and desired environmental condition. Measurement programs can at best approximate the state of the ambient atmosphere at a few points in a scenic vista viewed by an observer. To fully understand the visual effect of various changes in the concentration and distribution of optically important atmospheric pollutants requires the use of aerosol and radiative transfer models. Communication of the output of these models to scientists, decision makers and the public is best done by applying modern image-processing systems to generate synthetic images representing the modeled air quality conditions. This combination of modeling techniques has been under development for the past 15 yr. Initially, visual air quality simulations were limited by a lack of computational power to simplified models depicting Gaussian plumes or uniform haze conditions. Recent explosive growth in low cost, high powered computer technology has allowed the development of sophisticated aerosol and radiative transfer models that incorporate realistic terrain, multiple scattering, non-uniform illumination, varying spatial distribution, concentration and optical properties of atmospheric constituents, and relative humidity effects on aerosol scattering properties. This paper discusses these improved models and image-processing techniques in detail. Results addressing uniform and non-uniform layered haze conditions in both

  17. A dual-view digital tomosynthesis imaging technique for improved chest imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yuncheng; Lai, Chao-Jen; Wang, Tianpeng; Shaw, Chris C., E-mail: cshaw@mdanderson.org [Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77054 (United States)

    2015-09-15

    Purpose: Digital tomosynthesis (DTS) has been shown to be useful for reducing the overlapping of abnormalities with anatomical structures at various depth levels along the posterior–anterior (PA) direction in chest radiography. However, DTS provides crude three-dimensional (3D) images that have poor resolution in the lateral view and can only be displayed with reasonable quality in the PA view. Furthermore, the spillover of high-contrast objects from off-fulcrum planes generates artifacts that may impede the diagnostic use of the DTS images. In this paper, the authors describe and demonstrate the use of a dual-view DTS technique to improve the accuracy of the reconstructed volume image data for more accurate rendition of the anatomy and slice images with improved resolution and reduced artifacts, thus allowing the 3D image data to be viewed in views other than the PA view. Methods: With the dual-view DTS technique, limited angle scans are performed and projection images are acquired in two orthogonal views: PA and lateral. The dual-view projection data are used together to reconstruct 3D images using the maximum likelihood expectation maximization iterative algorithm. In this study, projection images were simulated or experimentally acquired over 360° using the scanning geometry for cone beam computed tomography (CBCT). While all projections were used to reconstruct CBCT images, selected projections were extracted and used to reconstruct single- and dual-view DTS images for comparison with the CBCT images. For realistic demonstration and comparison, a digital chest phantom derived from clinical CT images was used for the simulation study. An anthropomorphic chest phantom was imaged for the experimental study. The resultant dual-view DTS images were visually compared with the single-view DTS images and CBCT images for the presence of image artifacts and accuracy of CT numbers and anatomy and quantitatively compared with root-mean-square-deviation (RMSD) values

  18. Designing Solutions by a Student Centred Approach: Integration of Chemical Process Simulation with Statistical Tools to Improve Distillation Systems

    Directory of Open Access Journals (Sweden)

    Isabel M. Joao

    2017-09-01

    Full Text Available Projects thematically focused on simulation and statistical techniques for designing and optimizing chemical processes can be helpful in chemical engineering education in order to meet the needs of engineers. We argue for the relevance of the projects to improve a student centred approach and boost higher order thinking skills. This paper addresses the use of Aspen HYSYS by Portuguese chemical engineering master students to model distillation systems together with statistical experimental design techniques in order to optimize the systems highlighting the value of applying problem specific knowledge, simulation tools and sound statistical techniques. The paper summarizes the work developed by the students in order to model steady-state processes, dynamic processes and optimize the distillation systems emphasizing the benefits of the simulation tools and statistical techniques in helping the students learn how to learn. Students strengthened their domain specific knowledge and became motivated to rethink and improve chemical processes in their future chemical engineering profession. We discuss the main advantages of the methodology from the students’ and teachers perspective

  19. Fast, Accurate Memory Architecture Simulation Technique Using Memory Access Characteristics

    OpenAIRE

    小野, 貴継; 井上, 弘士; 村上, 和彰

    2007-01-01

    This paper proposes a fast and accurate memory architecture simulation technique. To design memory architecture, the first steps commonly involve using trace-driven simulation. However, expanding the design space makes the evaluation time increase. A fast simulation is achieved by a trace size reduction, but it reduces the simulation accuracy. Our approach can reduce the simulation time while maintaining the accuracy of the simulation results. In order to evaluate validity of proposed techniq...

  20. A Novel Cast Removal Training Simulation to Improve Patient Safety.

    Science.gov (United States)

    Brubacher, Jacob W; Karg, Jeffrey; Weinstock, Peter; Bae, Donald S

    2016-01-01

    Cast application and removal are essential to orthopedics and performed by providers of variable training. Simulation training and practice of proper cast application and removal may reduce injury, optimize outcomes, and reduce health care costs. The purpose of this educational initiative was to develop, validate, and implement a novel simulation trainer and curriculum to improve safety during cast removal. In all, 30 thermocouples (Omega, Stamford, CT) were applied to a radius fracture model (Sawbones, Vashon, WA). After reduction and cast application, a saw (Stryker, Kalamazoo, MI) was used to cut the cast with temperature recording. Both "good" and "poor" techniques-as established by consensus best practices-were used. Maximal temperatures were compared to known thresholds for thermal injury; humans experience pain at temperatures exceeding 47°C and contact temperatures exceeding 60°C may lead to epidermal necrosis. Construct validity was evaluated by assessing novice (postgraduate year 1), intermediate (postgraduate year 3), and expert (pediatric orthopedic attending) performance. With the "good" technique, mean peak temperatures were 43°C + 4.3°C. The highest recorded was 51.9°C. With the "poor" technique, mean peak temperature was 75.2°C + 17.3°C. The maximum temperature recorded with the "poor" technique was 112.4°C. Construct validity testing showed that novices had the highest increases in temperatures (12.9°C). There was a decline in heat generation as experience increased with the intermediate group (9.7°C), and the lowest heat generation was seen in the expert group (5.0°C). A novel task simulator and curriculum have been developed to assess competency and enhance performance in the application and removal of casts. There was a 32.2°C temperature decrease when the proper cast saw technique was used. Furthermore, the "poor" technique consistently achieved temperatures that would cause epidermal necrosis in patients. Clinical experience was a

  1. Framing quality improvement tools and techniques in healthcare the case of improvement leaders' guides.

    Science.gov (United States)

    Millar, Ross

    2013-01-01

    The purpose of this paper is to present a study of how quality improvement tools and techniques are framed within healthcare settings. The paper employs an interpretive approach to understand how quality improvement tools and techniques are mobilised and legitimated. It does so using a case study of the NHS Modernisation Agency Improvement Leaders' Guides in England. Improvement Leaders' Guides were framed within a service improvement approach encouraging the use of quality improvement tools and techniques within healthcare settings. Their use formed part of enacting tools and techniques across different contexts. Whilst this enactment was believed to support the mobilisation of tools and techniques, the experience also illustrated the challenges in distributing such approaches. The paper provides an important contribution in furthering our understanding of framing the "social act" of quality improvement. Given the ongoing emphasis on quality improvement in health systems and the persistent challenges involved, it also provides important information for healthcare leaders globally in seeking to develop, implement or modify similar tools and distribute leadership within health and social care settings.

  2. Model improvements to simulate charging in SEM

    Science.gov (United States)

    Arat, K. T.; Klimpel, T.; Hagen, C. W.

    2018-03-01

    Charging of insulators is a complex phenomenon to simulate since the accuracy of the simulations is very sensitive to the interaction of electrons with matter and electric fields. In this study, we report model improvements for a previously developed Monte-Carlo simulator to more accurately simulate samples that charge. The improvements include both modelling of low energy electron scattering and charging of insulators. The new first-principle scattering models provide a more realistic charge distribution cloud in the material, and a better match between non-charging simulations and experimental results. Improvements on charging models mainly focus on redistribution of the charge carriers in the material with an induced conductivity (EBIC) and a breakdown model, leading to a smoother distribution of the charges. Combined with a more accurate tracing of low energy electrons in the electric field, we managed to reproduce the dynamically changing charging contrast due to an induced positive surface potential.

  3. Atmospheric Pre-Corrected Differential Absorption Techniques to Retrieve Columnar Water Vapor: Theory and Simulations

    Science.gov (United States)

    Borel, Christoph C.; Schlaepfer, Daniel

    1996-01-01

    Two different approaches exist to retrieve columnar water vapor from imaging spectrometer data: (1) Differential absorption techniques based on: (a) Narrow-Wide (N/W) ratio between overlapping spectrally wide and narrow channels; (b) Continuum Interpolated Band Ratio (CIBR) between a measurement channel and the weighted sum of two reference channels. (2) Non-linear fitting techniques which are based on spectral radiative transfer calculations. The advantage of the first approach is computational speed and of the second, improved retrieval accuracy. Our goal was to improve the accuracy of the first technique using physics based on radiative transfer. Using a modified version of the Duntley equation, we derived an "Atmospheric Pre-corrected Differential Absorption" (APDA) technique and described an iterative scheme to retrieve water vapor on a pixel-by-pixel basis. Next we compared both, the CIBR and the APDA using the Duntley equation for MODTRAN3 computed irradiances, transmissions and path radiance (using the DISORT option). This simulation showed that the CIBR is very sensitive to reflectance effects and that the APDA performs much better. An extensive data set was created with the radiative transfer code 6S over 379 different ground reflectance spectra. The calculated relative water vapor error was reduced significantly for the APDA. The APDA technique had about 8% (vs. over 35% for the CIBR) of the 379 spectra with a relative water vapor error of greater than +5%. The APDA has been applied to 1991 and 1995 AVIRIS scenes which visually demonstrate the improvement over the CIBR technique.

  4. Atmospheric pre-corrected differential absorption techniques to retrieve columnar water vapor: Theory and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Borel, C.C.; Schlaepfer, D.

    1996-03-01

    Two different approaches exist to retrieve columnar water vapor from imaging spectrometer data: (1) Differential absorption techniques based on: (a) Narrow-Wide (N/W) ratio between overlapping spectrally wide and narrow channels (b) Continuum Interpolated Band Ratio (CIBR) between a measurement channel and the weighted sum of two reference channels; and (2) Non-linear fitting techniques which are based on spectral radiative transfer calculations. The advantage of the first approach is computational speed and of the second, improved retrieval accuracy. Our goal was to improve the accuracy of the first technique using physics based on radiative transfer. Using a modified version of the Duntley equation, we derived an {open_quote}Atmospheric Pre-corrected Differential Absorption{close_quote} (APDA) technique and described an iterative scheme to retrieve water vapor on a pixel-by-pixel basis. Next we compared both, the CIBR and the APDA using the Duntley equation for MODTRAN3 computed irradiances, transmissions and path radiance (using the DISORT option). This simulation showed that the CIBR is very sensitive to reflectance effects and that the APDA performs much better. An extensive data set was created with the radiative transfer code 6S over 379 different ground reflectance spectra. The calculated relative water vapor error was reduced significantly for the APDA. The APDA technique had about 8% (vs. over 35% for the CIBR) of the 379 spectra with a relative water vapor error of greater than {+-}5%. The APDA has been applied to 1991 and 1995 AVIRIS scenes which visually demonstrate the improvement over the CIBR technique.

  5. The Virtual Genetics Lab II: Improvements to a Freely Available Software Simulation of Genetics

    Science.gov (United States)

    White, Brian T.

    2012-01-01

    The Virtual Genetics Lab II (VGLII) is an improved version of the highly successful genetics simulation software, the Virtual Genetics Lab (VGL). The software allows students to use the techniques of genetic analysis to design crosses and interpret data to solve realistic genetics problems involving a hypothetical diploid insect. This is a brief…

  6. A Simulation-Based Quality Improvement Initiative Improves Pediatric Readiness in Community Hospitals.

    Science.gov (United States)

    Whitfill, Travis; Gawel, Marcie; Auerbach, Marc

    2017-07-17

    The National Pediatric Readiness Project Pediatric Readiness Survey (PRS) measured pediatric readiness in 4149 US emergency departments (EDs) and noted an average score of 69 on a 100-point scale. This readiness score consists of 6 domains: coordination of pediatric patient care (19/100), physician/nurse staffing and training (10/100), quality improvement activities (7/100), patient safety initiatives (14/100), policies and procedures (17/100), and availability of pediatric equipment (33/100). We aimed to assess and improve pediatric emergency readiness scores across Connecticut's hospitals. The aim of this study was to compare the National Pediatric Readiness Project readiness score before and after an in situ simulation-based assessment and quality improvement program in Connecticut hospitals. We leveraged in situ simulations to measure the quality of resuscitative care provided by interprofessional teams to 3 simulated patients (infant septic shock, infant seizure, and child cardiac arrest) presenting to their ED resuscitation bay. Assessments of EDs were made based on a composite quality score that was measured as the sum of 4 distinct domains: (1) adherence to sepsis guidelines, (2) adherence to cardiac arrest guidelines, (3) performance on seizure resuscitation, and (4) teamwork. After the simulation, a detailed report with scores, comparisons to other EDs, and a gap analysis were provided to sites. Based on this report, a regional children's hospital team worked collaboratively with each ED to develop action items and a timeline for improvements. The National Pediatric Readiness Project PRS scores, the primary outcome of this study, were measured before and after participation. Twelve community EDs in Connecticut participated in this project. The PRS scores were assessed before and after the intervention (simulation-based assessment and gap analysis/report-out). The average time between PRS assessments was 21 months. The PRS scores significantly improved 12

  7. Visualization needs and techniques for astrophysical simulations

    International Nuclear Information System (INIS)

    Kapferer, W; Riser, T

    2008-01-01

    Numerical simulations have evolved continuously towards being an important field in astrophysics, equivalent to theory and observation. Due to the enormous developments in computer sciences, both hardware- and software-architecture, state-of-the-art simulations produce huge amounts of raw data with increasing complexity. In this paper some aspects of problems in the field of visualization in numerical astrophysics in combination with possible solutions are given. Commonly used visualization packages along with a newly developed approach to real-time visualization, incorporating shader programming to uncover the computational power of modern graphics cards, are presented. With these techniques at hand, real-time visualizations help scientists to understand the coherences in the results of their numerical simulations. Furthermore a fundamental problem in data analysis, i.e. coverage of metadata on how a visualization was created, is highlighted.

  8. An analytical simulation technique for cone-beam CT and pinhole SPECT

    International Nuclear Information System (INIS)

    Zhang Xuezhu; Qi Yujin

    2011-01-01

    This study was aimed at developing an efficient simulation technique with an ordinary PC. The work involved derivation of mathematical operators, analytic phantom generations, and effective analytical projectors developing for cone-beam CT and pinhole SPECT imaging. The computer simulations based on the analytical projectors were developed by ray-tracing method for cone-beam CT and voxel-driven method for pinhole SPECT of degrading blurring. The 3D Shepp-Logan, Jaszczak and Defrise phantoms were used for simulation evaluations and image reconstructions. The reconstructed phantom images were of good accuracy with the phantoms. The results showed that the analytical simulation technique is an efficient tool for studying cone-beam CT and pinhole SPECT imaging. (authors)

  9. Space Geodetic Technique Co-location in Space: Simulation Results for the GRASP Mission

    Science.gov (United States)

    Kuzmicz-Cieslak, M.; Pavlis, E. C.

    2011-12-01

    The Global Geodetic Observing System-GGOS, places very stringent requirements in the accuracy and stability of future realizations of the International Terrestrial Reference Frame (ITRF): an origin definition at 1 mm or better at epoch and a temporal stability on the order of 0.1 mm/y, with similar numbers for the scale (0.1 ppb) and orientation components. These goals were derived from the requirements of Earth science problems that are currently the international community's highest priority. None of the geodetic positioning techniques can achieve this goal alone. This is due in part to the non-observability of certain attributes from a single technique. Another limitation is imposed from the extent and uniformity of the tracking network and the schedule of observational availability and number of suitable targets. The final limitation derives from the difficulty to "tie" the reference points of each technique at the same site, to an accuracy that will support the GGOS goals. The future GGOS network will address decisively the ground segment and to certain extent the space segment requirements. The JPL-proposed multi-technique mission GRASP (Geodetic Reference Antenna in Space) attempts to resolve the accurate tie between techniques, using their co-location in space, onboard a well-designed spacecraft equipped with GNSS receivers, a SLR retroreflector array, a VLBI beacon and a DORIS system. Using the anticipated system performance for all four techniques at the time the GGOS network is completed (ca 2020), we generated a number of simulated data sets for the development of a TRF. Our simulation studies examine the degree to which GRASP can improve the inter-technique "tie" issue compared to the classical approach, and the likely modus operandi for such a mission. The success of the examined scenarios is judged by the quality of the origin and scale definition of the resulting TRF.

  10. Tree Simulation Techniques for Integrated Safety Assessment

    International Nuclear Information System (INIS)

    Melendez Asensio, E.; Izquierdo Rocha, J.M.; Sanchez Perez, M.; Hortal Reymundo, J.; Perez Mulas, A.

    1999-01-01

    techniques are: (a) An unifying theory that should (i) establish the relationship among different approaches and, in particular, be able to demonstrate the standard safety assessment approach as a particular case, (ii) identify implicit assumptions in present practice and (iii) establish a sound scientific reference for an ideal treatment in order to judge the relative importance of implicit and explicit assumptions. In addition, the theoretical developments help to identify the type of applications where the new developments will be a necessary requirement. (b) The capability for simulation of trees. By this we mean the techniques required to be able to efficiently simulate all branches. Historically algorithms able to do this were already implemented in earlier pioneering work for discrete number of branches while stochastic branching requires Montecarlo techniques. (c) The capability to incorporate new types of branching, particularly operator actions. This paper shortly reviews these aspects and justifies in that frame our particular development, denoted here as Integrated Safety Assessment methodology. In this method, the dynamics of the event is followed by transient simulation in tree form, building a Setpoint or Deterministic Dynamic Event Tree (DDET). When a setpoint that should trigger the actuation of a protection is crossed, the tree is opened in branches corresponding to different functioning states of the protection device and each branch followed by the engineering simulator. One of these states is the nominal state, which, in the PSAs, is Associated to the success criterion of the system

  11. Using simulation training to improve shoulder dystocia documentation.

    Science.gov (United States)

    Goffman, Dena; Heo, Hye; Chazotte, Cynthia; Merkatz, Irwin R; Bernstein, Peter S

    2008-12-01

    To estimate whether shoulder dystocia documentation could be improved with a simulation-based educational experience. Obstetricians at our institution (n=71) participated in an unanticipated simulated shoulder dystocia followed by an educational debriefing session. A second shoulder dystocia simulation was completed at a later date. Delivery notes were a required component of each simulation. Notes were evaluated using a standardized checklist for 16 key components. One point was awarded for each element present. Wilcoxon signed rank tests were used to compare documentation between simulations. Participants consisted of 43 (61%) attending and 28 (39%) resident physicians. Ages ranged from 25-63 years (mean+/-standard deviation 37.0+/-9.0), and 75% were female. Years of obstetric experience for our attendings ranged from 4 to 31 years (14.5+/-8.1). Documentation scores were significantly improved after training. Attendings' baseline documentation scores were 8.5+/-2.2 and improved to 9.4+/-2.3, P=.03. Residents' documentation scores also improved (9.0+/-2.1 compared with 10.6+/-2.2, P=.001). In particular, improvement was seen in two components of documentation: 1) providers present for shoulder dystocia (P=.007) and 2) which shoulder was anterior (P<.001). No improvement was seen in standard delivery note components (eg, date, time) or infant characteristics (eg, weight, Apgar scores). Although we showed a significant improvement in the quality of documentation through this simulation program, notes were still suboptimal. Use of standardized forms for shoulder dystocia delivery notes may provide the best solution to ensure appropriate documentation. II.

  12. Research on integrated simulation of fluid-structure system by computation science techniques

    International Nuclear Information System (INIS)

    Yamaguchi, Akira

    1996-01-01

    In Power Reactor and Nuclear Fuel Development Corporation, the research on the integrated simulation of fluid-structure system by computation science techniques has been carried out, and by its achievement, the verification of plant systems which has depended on large scale experiments is substituted by computation science techniques, in this way, it has been aimed at to reduce development costs and to attain the optimization of FBR systems. For the purpose, it is necessary to establish the technology for integrally and accurately analyzing complicated phenomena (simulation technology), the technology for applying it to large scale problems (speed increasing technology), and the technology for assuring the reliability of the results of analysis when simulation technology is utilized for the permission and approval of FBRs (verifying technology). The simulation of fluid-structure interaction, the heat flow simulation in the space with complicated form and the related technologies are explained. As the utilization of computation science techniques, the elucidation of phenomena by numerical experiment and the numerical simulation as the substitute for tests are discussed. (K.I.)

  13. A New Screening Methodology for Improved Oil Recovery Processes Using Soft-Computing Techniques

    Science.gov (United States)

    Parada, Claudia; Ertekin, Turgay

    2010-05-01

    The first stage of production of any oil reservoir involves oil displacement by natural drive mechanisms such as solution gas drive, gas cap drive and gravity drainage. Typically, improved oil recovery (IOR) methods are applied to oil reservoirs that have been depleted naturally. In more recent years, IOR techniques are applied to reservoirs even before their natural energy drive is exhausted by primary depletion. Descriptive screening criteria for IOR methods are used to select the appropriate recovery technique according to the fluid and rock properties. This methodology helps in assessing the most suitable recovery process for field deployment of a candidate reservoir. However, the already published screening guidelines neither provide information about the expected reservoir performance nor suggest a set of project design parameters, which can be used towards the optimization of the process. In this study, artificial neural networks (ANN) are used to build a high-performance neuro-simulation tool for screening different improved oil recovery techniques: miscible injection (CO2 and N2), waterflooding and steam injection processes. The simulation tool consists of proxy models that implement a multilayer cascade feedforward back propagation network algorithm. The tool is intended to narrow the ranges of possible scenarios to be modeled using conventional simulation, reducing the extensive time and energy spent in dynamic reservoir modeling. A commercial reservoir simulator is used to generate the data to train and validate the artificial neural networks. The proxy models are built considering four different well patterns with different well operating conditions as the field design parameters. Different expert systems are developed for each well pattern. The screening networks predict oil production rate and cumulative oil production profiles for a given set of rock and fluid properties, and design parameters. The results of this study show that the networks are

  14. Improvements to information management systems simulator

    Science.gov (United States)

    Bilek, R. W.

    1972-01-01

    The performance of personnel in the augmentation and improvement of the interactive IMSIM information management simulation model is summarized. With this augmented model, NASA now has even greater capabilities for the simulation of computer system configurations, data processing loads imposed on these configurations, and executive software to control system operations. Through these simulations, NASA has an extremely cost effective capability for the design and analysis of computer-based data management systems.

  15. Improving blood sample logistics using simulation

    DEFF Research Database (Denmark)

    Jørgensen, Pelle Morten Thomas; Jacobsen, Peter

    2012-01-01

    Using simulation as an approach to display and improve internal logistics and handling at hospitals has great potential. This research will show how a simulation model can be used to evaluate changes made to two different cases of transportation of blood samples at a hospital, by evaluating...

  16. SU-E-I-07: An Improved Technique for Scatter Correction in PET

    International Nuclear Information System (INIS)

    Lin, S; Wang, Y; Lue, K; Lin, H; Chuang, K

    2014-01-01

    Purpose: In positron emission tomography (PET), the single scatter simulation (SSS) algorithm is widely used for scatter estimation in clinical scans. However, bias usually occurs at the essential steps of scaling the computed SSS distribution to real scatter amounts by employing the scatter-only projection tail. The bias can be amplified when the scatter-only projection tail is too small, resulting in incorrect scatter correction. To this end, we propose a novel scatter calibration technique to accurately estimate the amount of scatter using pre-determined scatter fraction (SF) function instead of the employment of scatter-only tail information. Methods: As the SF depends on the radioactivity distribution and the attenuating material of the patient, an accurate theoretical relation cannot be devised. Instead, we constructed an empirical transformation function between SFs and average attenuation coefficients based on a serious of phantom studies with different sizes and materials. From the average attenuation coefficient, the predicted SFs were calculated using empirical transformation function. Hence, real scatter amount can be obtained by scaling the SSS distribution with the predicted SFs. The simulation was conducted using the SimSET. The Siemens Biograph™ 6 PET scanner was modeled in this study. The Software for Tomographic Image Reconstruction (STIR) was employed to estimate the scatter and reconstruct images. The EEC phantom was adopted to evaluate the performance of our proposed technique. Results: The scatter-corrected image of our method demonstrated improved image contrast over that of SSS. For our technique and SSS of the reconstructed images, the normalized standard deviation were 0.053 and 0.182, respectively; the root mean squared errors were 11.852 and 13.767, respectively. Conclusion: We have proposed an alternative method to calibrate SSS (C-SSS) to the absolute scatter amounts using SF. This method can avoid the bias caused by the insufficient

  17. SU-E-I-07: An Improved Technique for Scatter Correction in PET

    Energy Technology Data Exchange (ETDEWEB)

    Lin, S; Wang, Y; Lue, K; Lin, H; Chuang, K [Chuang, National Tsing Hua University, Hsichu, Taiwan (China)

    2014-06-01

    Purpose: In positron emission tomography (PET), the single scatter simulation (SSS) algorithm is widely used for scatter estimation in clinical scans. However, bias usually occurs at the essential steps of scaling the computed SSS distribution to real scatter amounts by employing the scatter-only projection tail. The bias can be amplified when the scatter-only projection tail is too small, resulting in incorrect scatter correction. To this end, we propose a novel scatter calibration technique to accurately estimate the amount of scatter using pre-determined scatter fraction (SF) function instead of the employment of scatter-only tail information. Methods: As the SF depends on the radioactivity distribution and the attenuating material of the patient, an accurate theoretical relation cannot be devised. Instead, we constructed an empirical transformation function between SFs and average attenuation coefficients based on a serious of phantom studies with different sizes and materials. From the average attenuation coefficient, the predicted SFs were calculated using empirical transformation function. Hence, real scatter amount can be obtained by scaling the SSS distribution with the predicted SFs. The simulation was conducted using the SimSET. The Siemens Biograph™ 6 PET scanner was modeled in this study. The Software for Tomographic Image Reconstruction (STIR) was employed to estimate the scatter and reconstruct images. The EEC phantom was adopted to evaluate the performance of our proposed technique. Results: The scatter-corrected image of our method demonstrated improved image contrast over that of SSS. For our technique and SSS of the reconstructed images, the normalized standard deviation were 0.053 and 0.182, respectively; the root mean squared errors were 11.852 and 13.767, respectively. Conclusion: We have proposed an alternative method to calibrate SSS (C-SSS) to the absolute scatter amounts using SF. This method can avoid the bias caused by the insufficient

  18. Taxi Time Prediction at Charlotte Airport Using Fast-Time Simulation and Machine Learning Techniques

    Science.gov (United States)

    Lee, Hanbong

    2016-01-01

    Accurate taxi time prediction is required for enabling efficient runway scheduling that can increase runway throughput and reduce taxi times and fuel consumptions on the airport surface. Currently NASA and American Airlines are jointly developing a decision-support tool called Spot and Runway Departure Advisor (SARDA) that assists airport ramp controllers to make gate pushback decisions and improve the overall efficiency of airport surface traffic. In this presentation, we propose to use Linear Optimized Sequencing (LINOS), a discrete-event fast-time simulation tool, to predict taxi times and provide the estimates to the runway scheduler in real-time airport operations. To assess its prediction accuracy, we also introduce a data-driven analytical method using machine learning techniques. These two taxi time prediction methods are evaluated with actual taxi time data obtained from the SARDA human-in-the-loop (HITL) simulation for Charlotte Douglas International Airport (CLT) using various performance measurement metrics. Based on the taxi time prediction results, we also discuss how the prediction accuracy can be affected by the operational complexity at this airport and how we can improve the fast time simulation model before implementing it with an airport scheduling algorithm in a real-time environment.

  19. Combination technique for improving natural convection cooling in electronics

    Energy Technology Data Exchange (ETDEWEB)

    Florio, L.A.; Harnoy, A. [Department of Mechanical Engineering, New Jersey Institute of Technology, University Heights, Newark, NJ 07102 (United States)

    2007-01-15

    The combination of an appropriately placed cross-flow opening and a strategically positioned transversely vibrating plate is proposed as a means of augmenting pure natural convection in a vertical channel. This method is intended to provide a more efficient, reliable, and consumer conscious alternative to conventional techniques for lower power dissipating devices where standard natural convection cooling proves insufficient. Two-dimensional numerical simulations are employed to investigate this combination method using models consisting of a vertical channel containing two rectangular heat sources which are attached to a vertical mounting board, as well as a transversely oscillating plate and a cross-flow opening in the mounting board area between the two heat sources. Varied parameters and geometric configurations are studied. The results indicate the combined effects of the vibrating plate and the opening flow have the potential to cause significant improvement in the thermal conditions over pure natural convection. As much as a 70% improvement in the local heat transfer coefficient from that for a system with a board opening but without a vibrating plate was attained. (author)

  20. Pilot study: evaluation of the use of the convergent interview technique in understanding the perception of surgical design and simulation.

    Science.gov (United States)

    Logan, Heather; Wolfaardt, Johan; Boulanger, Pierre; Hodgetts, Bill; Seikaly, Hadi

    2013-06-19

    It is important to understand the perceived value of surgical design and simulation (SDS) amongst surgeons, as this will influence its implementation in clinical settings. The purpose of the present study was to examine the application of the convergent interview technique in the field of surgical design and simulation and evaluate whether the technique would uncover new perceptions of virtual surgical planning (VSP) and medical models not discovered by other qualitative case-based techniques. Five surgeons were asked to participate in the study. Each participant was interviewed following the convergent interview technique. After each interview, the interviewer interpreted the information by seeking agreements and disagreements among the interviewees in order to understand the key concepts in the field of SDS. Fifteen important issues were extracted from the convergent interviews. In general, the convergent interview was an effective technique in collecting information about the perception of clinicians. The study identified three areas where the technique could be improved upon for future studies in the SDS field.

  1. A computer code to simulate X-ray imaging techniques

    International Nuclear Information System (INIS)

    Duvauchelle, Philippe; Freud, Nicolas; Kaftandjian, Valerie; Babot, Daniel

    2000-01-01

    A computer code was developed to simulate the operation of radiographic, radioscopic or tomographic devices. The simulation is based on ray-tracing techniques and on the X-ray attenuation law. The use of computer-aided drawing (CAD) models enables simulations to be carried out with complex three-dimensional (3D) objects and the geometry of every component of the imaging chain, from the source to the detector, can be defined. Geometric unsharpness, for example, can be easily taken into account, even in complex configurations. Automatic translations or rotations of the object can be performed to simulate radioscopic or tomographic image acquisition. Simulations can be carried out with monochromatic or polychromatic beam spectra. This feature enables, for example, the beam hardening phenomenon to be dealt with or dual energy imaging techniques to be studied. The simulation principle is completely deterministic and consequently the computed images present no photon noise. Nevertheless, the variance of the signal associated with each pixel of the detector can be determined, which enables contrast-to-noise ratio (CNR) maps to be computed, in order to predict quantitatively the detectability of defects in the inspected object. The CNR is a relevant indicator for optimizing the experimental parameters. This paper provides several examples of simulated images that illustrate some of the rich possibilities offered by our software. Depending on the simulation type, the computation time order of magnitude can vary from 0.1 s (simple radiographic projection) up to several hours (3D tomography) on a PC, with a 400 MHz microprocessor. Our simulation tool proves to be useful in developing new specific applications, in choosing the most suitable components when designing a new testing chain, and in saving time by reducing the number of experimental tests

  2. A computer code to simulate X-ray imaging techniques

    Energy Technology Data Exchange (ETDEWEB)

    Duvauchelle, Philippe E-mail: philippe.duvauchelle@insa-lyon.fr; Freud, Nicolas; Kaftandjian, Valerie; Babot, Daniel

    2000-09-01

    A computer code was developed to simulate the operation of radiographic, radioscopic or tomographic devices. The simulation is based on ray-tracing techniques and on the X-ray attenuation law. The use of computer-aided drawing (CAD) models enables simulations to be carried out with complex three-dimensional (3D) objects and the geometry of every component of the imaging chain, from the source to the detector, can be defined. Geometric unsharpness, for example, can be easily taken into account, even in complex configurations. Automatic translations or rotations of the object can be performed to simulate radioscopic or tomographic image acquisition. Simulations can be carried out with monochromatic or polychromatic beam spectra. This feature enables, for example, the beam hardening phenomenon to be dealt with or dual energy imaging techniques to be studied. The simulation principle is completely deterministic and consequently the computed images present no photon noise. Nevertheless, the variance of the signal associated with each pixel of the detector can be determined, which enables contrast-to-noise ratio (CNR) maps to be computed, in order to predict quantitatively the detectability of defects in the inspected object. The CNR is a relevant indicator for optimizing the experimental parameters. This paper provides several examples of simulated images that illustrate some of the rich possibilities offered by our software. Depending on the simulation type, the computation time order of magnitude can vary from 0.1 s (simple radiographic projection) up to several hours (3D tomography) on a PC, with a 400 MHz microprocessor. Our simulation tool proves to be useful in developing new specific applications, in choosing the most suitable components when designing a new testing chain, and in saving time by reducing the number of experimental tests.

  3. Fast simulation techniques for switching converters

    Science.gov (United States)

    King, Roger J.

    1987-01-01

    Techniques for simulating a switching converter are examined. The state equations for the equivalent circuits, which represent the switching converter, are presented and explained. The uses of the Newton-Raphson iteration, low ripple approximation, half-cycle symmetry, and discrete time equations to compute the interval durations are described. An example is presented in which these methods are illustrated by applying them to a parallel-loaded resonant inverter with three equivalent circuits for its continuous mode of operation.

  4. Test/score/report: Simulation techniques for automating the test process

    Science.gov (United States)

    Hageman, Barbara H.; Sigman, Clayton B.; Koslosky, John T.

    1994-01-01

    A Test/Score/Report capability is currently being developed for the Transportable Payload Operations Control Center (TPOCC) Advanced Spacecraft Simulator (TASS) system which will automate testing of the Goddard Space Flight Center (GSFC) Payload Operations Control Center (POCC) and Mission Operations Center (MOC) software in three areas: telemetry decommutation, spacecraft command processing, and spacecraft memory load and dump processing. Automated computer control of the acceptance test process is one of the primary goals of a test team. With the proper simulation tools and user interface, the task of acceptance testing, regression testing, and repeatability of specific test procedures of a ground data system can be a simpler task. Ideally, the goal for complete automation would be to plug the operational deliverable into the simulator, press the start button, execute the test procedure, accumulate and analyze the data, score the results, and report the results to the test team along with a go/no recommendation to the test team. In practice, this may not be possible because of inadequate test tools, pressures of schedules, limited resources, etc. Most tests are accomplished using a certain degree of automation and test procedures that are labor intensive. This paper discusses some simulation techniques that can improve the automation of the test process. The TASS system tests the POCC/MOC software and provides a score based on the test results. The TASS system displays statistics on the success of the POCC/MOC system processing in each of the three areas as well as event messages pertaining to the Test/Score/Report processing. The TASS system also provides formatted reports documenting each step performed during the tests and the results of each step. A prototype of the Test/Score/Report capability is available and currently being used to test some POCC/MOC software deliveries. When this capability is fully operational it should greatly reduce the time necessary

  5. optimal assembly line balancing using simulation techniques

    African Journals Online (AJOL)

    user

    Department of Mechanical Engineering ... perspective on how the business operates, and ... Process simulation allows management ... improvement and change since it would be a costly ... The work content performed on an assembly line.

  6. Parallel Reservoir Simulations with Sparse Grid Techniques and Applications to Wormhole Propagation

    KAUST Repository

    Wu, Yuanqing

    2015-01-01

    the traditional simulation technique relying on the Darcy framework, we propose a new framework called Darcy-Brinkman-Forchheimer framework to simulate wormhole propagation. Furthermore, to process the large quantity of cells in the simulation grid and shorten

  7. A NOVEL TECHNIQUE TO IMPROVE PHOTOMETRY IN CONFUSED IMAGES USING GRAPHS AND BAYESIAN PRIORS

    International Nuclear Information System (INIS)

    Safarzadeh, Mohammadtaher; Ferguson, Henry C.; Lu, Yu; Inami, Hanae; Somerville, Rachel S.

    2015-01-01

    We present a new technique for overcoming confusion noise in deep far-infrared Herschel space telescope images making use of prior information from shorter λ < 2 μm wavelengths. For the deepest images obtained by Herschel, the flux limit due to source confusion is about a factor of three brighter than the flux limit due to instrumental noise and (smooth) sky background. We have investigated the possibility of de-confusing simulated Herschel PACS 160 μm images by using strong Bayesian priors on the positions and weak priors on the flux of sources. We find the blended sources and group them together and simultaneously fit their fluxes. We derive the posterior probability distribution function of fluxes subject to these priors through Monte Carlo Markov Chain (MCMC) sampling by fitting the image. Assuming we can predict the FIR flux of sources based on the ultraviolet-optical part of their SEDs to within an order of magnitude, the simulations show that we can obtain reliable fluxes and uncertainties at least a factor of three fainter than the confusion noise limit of 3σ c = 2.7 mJy in our simulated PACS-160 image. This technique could in principle be used to mitigate the effects of source confusion in any situation where one has prior information of positions and plausible fluxes of blended sources. For Herschel, application of this technique will improve our ability to constrain the dust content in normal galaxies at high redshift

  8. Student perception of two different simulation techniques in oral and maxillofacial surgery undergraduate training.

    Science.gov (United States)

    Lund, Bodil; Fors, Uno; Sejersen, Ronny; Sallnäs, Eva-Lotta; Rosén, Annika

    2011-10-12

    Yearly surveys among the undergraduate students in oral and maxillofacial surgery at Karolinska Institutet have conveyed a wish for increased clinical training, and in particular, in surgical removal of mandibular third molars. Due to lack of resources, this kind of clinical supervision has so far not been possible to implement. One possible solution to this problem might be to introduce simulation into the curriculum. The purpose of this study was to investigate undergraduate students' perception of two different simulation methods for practicing clinical reasoning skills and technical skills in oral and maxillofacial surgery. Forty-seven students participating in the oral and maxillofacial surgery course at Karolinska Institutet during their final year were included. Three different oral surgery patient cases were created in a Virtual Patient (VP) Simulation system (Web-SP) and used for training clinical reasoning. A mandibular third molar surgery simulator with tactile feedback, providing hands on training in the bone removal and tooth sectioning in third molar surgery, was also tested. A seminar was performed using the combination of these two simulators where students' perception of the two different simulation methods was assessed by means of a questionnaire. The response rate was 91.5% (43/47). The students were positive to the VP cases, although they rated their possible improvement of clinical reasoning skills as moderate. The students' perception of improved technical skills after training in the mandibular third molar surgery simulator was rated high. The majority of the students agreed that both simulation techniques should be included in the curriculum and strongly agreed that it was a good idea to use the two simulators in concert. The importance of feedback from the senior experts during simulator training was emphasised. The two tested simulation methods were well accepted and most students agreed that the future curriculum would benefit from

  9. Weighted Least Squares Techniques for Improved Received Signal Strength Based Localization

    Directory of Open Access Journals (Sweden)

    José R. Casar

    2011-09-01

    Full Text Available The practical deployment of wireless positioning systems requires minimizing the calibration procedures while improving the location estimation accuracy. Received Signal Strength localization techniques using propagation channel models are the simplest alternative, but they are usually designed under the assumption that the radio propagation model is to be perfectly characterized a priori. In practice, this assumption does not hold and the localization results are affected by the inaccuracies of the theoretical, roughly calibrated or just imperfect channel models used to compute location. In this paper, we propose the use of weighted multilateration techniques to gain robustness with respect to these inaccuracies, reducing the dependency of having an optimal channel model. In particular, we propose two weighted least squares techniques based on the standard hyperbolic and circular positioning algorithms that specifically consider the accuracies of the different measurements to obtain a better estimation of the position. These techniques are compared to the standard hyperbolic and circular positioning techniques through both numerical simulations and an exhaustive set of real experiments on different types of wireless networks (a wireless sensor network, a WiFi network and a Bluetooth network. The algorithms not only produce better localization results with a very limited overhead in terms of computational cost but also achieve a greater robustness to inaccuracies in channel modeling.

  10. Integration of scheduling and discrete event simulation systems to improve production flow planning

    Science.gov (United States)

    Krenczyk, D.; Paprocka, I.; Kempa, W. M.; Grabowik, C.; Kalinowski, K.

    2016-08-01

    The increased availability of data and computer-aided technologies such as MRPI/II, ERP and MES system, allowing producers to be more adaptive to market dynamics and to improve production scheduling. Integration of production scheduling and computer modelling, simulation and visualization systems can be useful in the analysis of production system constraints related to the efficiency of manufacturing systems. A integration methodology based on semi-automatic model generation method for eliminating problems associated with complexity of the model and labour-intensive and time-consuming process of simulation model creation is proposed. Data mapping and data transformation techniques for the proposed method have been applied. This approach has been illustrated through examples of practical implementation of the proposed method using KbRS scheduling system and Enterprise Dynamics simulation system.

  11. Technique for in situ leach simulation of uranium ores

    International Nuclear Information System (INIS)

    Grant, D.C.; Seidel, D.C.; Nichols, I.L.

    1985-01-01

    In situ uranium mining offers the advantages of minimal environmental disturbance, low capital and operating costs, and reduced mining development time. It is becoming an increasingly attractive mining method for the recovery of uranium from secondary ore deposits. In order to better understand the process, a laboratory technique was developed and used to study and simulate both the chemical and physical phenomena occurring in ore bodies during in situ leaching. The laboratory simulation technique has been used to determine effects of leaching variables on permeability, uranium recovery, and post-leach aquifer restoration. This report describes the simulation system and testing procedure in sufficient detail to allow the construction of the system, and to perform the desired leaching tests. With construction of such a system, in situ leaching of a given ore using various leach conditions can be evaluated relatively rapidly in the laboratory. Not only could optimum leach conditions be selected for existing ore bodies, but also exploitation of new ore bodies could be accelerated. 8 references, 8 figures, 2 tables

  12. Improving operator training and performance through simulator observations

    International Nuclear Information System (INIS)

    Flynn, J.P.

    1987-01-01

    This paper describes the methods and results of INPO observations of simulator training for licensed operators. It discusses the history of the observation program to the present. Effective methods for conducting and documenting simulator observations are discussed. The methods used to analyze the observations is also discussed. The major conclusion of the analysis is that opportunities exist for improvement in the use of emergency operating procedures. Teamwork, communication, and simulator instructor skills are also areas where improvement could be made

  13. Preparing systems engineering and computing science students in disciplined methods, quantitative, and advanced statistical techniques to improve process performance

    Science.gov (United States)

    McCray, Wilmon Wil L., Jr.

    The research was prompted by a need to conduct a study that assesses process improvement, quality management and analytical techniques taught to students in U.S. colleges and universities undergraduate and graduate systems engineering and the computing science discipline (e.g., software engineering, computer science, and information technology) degree programs during their academic training that can be applied to quantitatively manage processes for performance. Everyone involved in executing repeatable processes in the software and systems development lifecycle processes needs to become familiar with the concepts of quantitative management, statistical thinking, process improvement methods and how they relate to process-performance. Organizations are starting to embrace the de facto Software Engineering Institute (SEI) Capability Maturity Model Integration (CMMI RTM) Models as process improvement frameworks to improve business processes performance. High maturity process areas in the CMMI model imply the use of analytical, statistical, quantitative management techniques, and process performance modeling to identify and eliminate sources of variation, continually improve process-performance; reduce cost and predict future outcomes. The research study identifies and provides a detail discussion of the gap analysis findings of process improvement and quantitative analysis techniques taught in U.S. universities systems engineering and computing science degree programs, gaps that exist in the literature, and a comparison analysis which identifies the gaps that exist between the SEI's "healthy ingredients " of a process performance model and courses taught in U.S. universities degree program. The research also heightens awareness that academicians have conducted little research on applicable statistics and quantitative techniques that can be used to demonstrate high maturity as implied in the CMMI models. The research also includes a Monte Carlo simulation optimization

  14. Image Improvement Techniques

    Science.gov (United States)

    Shine, R. A.

    1997-05-01

    Over the last decade, a repertoire of techniques have been developed and/or refined to improve the quality of high spatial resolution solar movies taken from ground based observatories. These include real time image motion corrections, frame selection, phase diversity measurements of the wavefront, and extensive post processing to partially remove atmospheric distortion. Their practical application has been made possible by the increasing availability and decreasing cost of large CCD's with fast digital readouts and high speed computer workstations with large memories. Most successful have been broad band (0.3 to 10 nm) filtergram movies which can use exposure times of 10 to 30 ms, short enough to ``freeze'' atmospheric motions. Even so, only a handful of movies with excellent image quality for more than a hour have been obtained to date. Narrowband filtergrams (about 0.01 nm), such as those required for constructing magnetograms and Dopplergrams, have been more challenging although some single images approach the quality of the best continuum images. Some promising new techniques and instruments, together with persistence and good luck, should continue the progress made in the last several years.

  15. Improving computational efficiency of Monte Carlo simulations with variance reduction

    International Nuclear Information System (INIS)

    Turner, A.; Davis, A.

    2013-01-01

    CCFE perform Monte-Carlo transport simulations on large and complex tokamak models such as ITER. Such simulations are challenging since streaming and deep penetration effects are equally important. In order to make such simulations tractable, both variance reduction (VR) techniques and parallel computing are used. It has been found that the application of VR techniques in such models significantly reduces the efficiency of parallel computation due to 'long histories'. VR in MCNP can be accomplished using energy-dependent weight windows. The weight window represents an 'average behaviour' of particles, and large deviations in the arriving weight of a particle give rise to extreme amounts of splitting being performed and a long history. When running on parallel clusters, a long history can have a detrimental effect on the parallel efficiency - if one process is computing the long history, the other CPUs complete their batch of histories and wait idle. Furthermore some long histories have been found to be effectively intractable. To combat this effect, CCFE has developed an adaptation of MCNP which dynamically adjusts the WW where a large weight deviation is encountered. The method effectively 'de-optimises' the WW, reducing the VR performance but this is offset by a significant increase in parallel efficiency. Testing with a simple geometry has shown the method does not bias the result. This 'long history method' has enabled CCFE to significantly improve the performance of MCNP calculations for ITER on parallel clusters, and will be beneficial for any geometry combining streaming and deep penetration effects. (authors)

  16. Reliability assessment of restructured power systems using reliability network equivalent and pseudo-sequential simulation techniques

    International Nuclear Information System (INIS)

    Ding, Yi; Wang, Peng; Goel, Lalit; Billinton, Roy; Karki, Rajesh

    2007-01-01

    This paper presents a technique to evaluate reliability of a restructured power system with a bilateral market. The proposed technique is based on the combination of the reliability network equivalent and pseudo-sequential simulation approaches. The reliability network equivalent techniques have been implemented in the Monte Carlo simulation procedure to reduce the computational burden of the analysis. Pseudo-sequential simulation has been used to increase the computational efficiency of the non-sequential simulation method and to model the chronological aspects of market trading and system operation. Multi-state Markov models for generation and transmission systems are proposed and implemented in the simulation. A new load shedding scheme is proposed during generation inadequacy and network congestion to minimize the load curtailment. The IEEE reliability test system (RTS) is used to illustrate the technique. (author)

  17. Applications of process improvement techniques to improve workflow in abdominal imaging.

    Science.gov (United States)

    Tamm, Eric Peter

    2016-03-01

    Major changes in the management and funding of healthcare are underway that will markedly change the way radiology studies will be reimbursed. The result will be the need to deliver radiology services in a highly efficient manner while maintaining quality. The science of process improvement provides a practical approach to improve the processes utilized in radiology. This article will address in a step-by-step manner how to implement process improvement techniques to improve workflow in abdominal imaging.

  18. An Improved SPH Technique for Fracture Modeling

    National Research Council Canada - National Science Library

    Libersky, Larry

    2000-01-01

    .... With these improvements, the MAGI code could solve the enormously complex problem of simulating Behind-Armor-Debris and subsequent interaction of the spall cloud with threat target components as well...

  19. Simulation for IT Service Desk Improvement

    Directory of Open Access Journals (Sweden)

    Peter Bober

    2014-07-01

    Full Text Available IT service desk is a complex service that IT service company provides to its customers. This article provides a methodology which uses discrete-event simulation to help IT service management to make decision and to plan service strategy. Simulation model considers learning ability of service desk agents and growth of knowledge database of the company. Model shows how the learning curve influences the time development of service desk quality and efficiency. This article promotes using simulation to define quantitative goals for the service desk improvement.

  20. Integration of quality improvement and cost-efficiency through industrial improvement techniques

    Directory of Open Access Journals (Sweden)

    Vink JP

    2016-06-01

    Full Text Available Jasper P Vink,1 Maxime T Rigaudy,1,2 Karl O Elmqvist11Imperial College Business School, Imperial College London, London, 2Hull York Medical School, York, UKIn this journal, Crema and Verbano1 discussed the importance of defining quality of health care and how quality can be improved through various industrial instruments and techniques. Quality of health care is a heavily debated topic that requires a wide scope of considerations across the many stakeholders of the health system. We acknowledge Crema and Verbano’s arguments that patient safety is a basic pillar of quality, upon which we would like to expand by highlighting the clinical effectiveness and patient-reported outcomes, which are the two further crucial components of quality. The arguments made regarding quality improvement techniques and cost efficiency in health care provision are insightful, yet appear to make a distinction between efforts to improve quality, eliminate waste from processes, and cut costs in health care provision. We would argue that in fact these achievements are all closely related and can be achieved simultaneously, if the industrial techniques of quality management are applied adequately.View the original paper by Crema and Verbano.

  1. A New V2G Control Strategy for Load Factor Improvement Using Smoothing Technique

    Directory of Open Access Journals (Sweden)

    CHANHOM, P.

    2017-08-01

    Full Text Available This paper proposes a new vehicle-to-grid (V2G control strategy for improving the load factor in the power network. To operate the proposed strategy, the available storage capacity of the PEVs’ batteries is considered as a battery energy storage system (BESS for charging and discharging an amount of power corresponding to the V2G power command. Due to the remarkable advantages of the technique so-called simple moving average, it is selected for applying in the proposed V2G control strategy. In this research, for investigating the load factor improvement, the essential data including the daily-load profiles with 7-day and 14-day periods are used for the 3 studied cases. These 3 studied cases present the power network with variation of the PEVs locations for describing the PEVs usage and charging or discharging behavior. The performance of the proposed strategy is simulated and verified by the MATPOWER software. The simulation results show that the load factors of the 3 studied cases are improved. Moreover, the encouragement of energy arbitrage for the PEVs owners is also discussed in this paper.

  2. System design and improvement of an emergency department using Simulation-Based Multi-Objective Optimization

    International Nuclear Information System (INIS)

    Uriarte, A Goienetxea; Zúñiga, E Ruiz; Moris, M Urenda; Ng, A H C

    2015-01-01

    Discrete Event Simulation (DES) is nowadays widely used to support decision makers in system analysis and improvement. However, the use of simulation for improving stochastic logistic processes is not common among healthcare providers. The process of improving healthcare systems involves the necessity to deal with trade-off optimal solutions that take into consideration a multiple number of variables and objectives. Complementing DES with Multi-Objective Optimization (SMO) creates a superior base for finding these solutions and in consequence, facilitates the decision-making process. This paper presents how SMO has been applied for system improvement analysis in a Swedish Emergency Department (ED). A significant number of input variables, constraints and objectives were considered when defining the optimization problem. As a result of the project, the decision makers were provided with a range of optimal solutions which reduces considerably the length of stay and waiting times for the ED patients. SMO has proved to be an appropriate technique to support healthcare system design and improvement processes. A key factor for the success of this project has been the involvement and engagement of the stakeholders during the whole process. (paper)

  3. Improving shoulder dystocia management among resident and attending physicians using simulations.

    Science.gov (United States)

    Goffman, Dena; Heo, Hye; Pardanani, Setul; Merkatz, Irwin R; Bernstein, Peter S

    2008-09-01

    The objective of the study was to determine whether a simulation-based educational program would improve residents' and attending physicians' performance in a simulated shoulder dystocia. Seventy-one obstetricians participated in an unanticipated simulated shoulder dystocia, an educational debriefing session, and a subsequent shoulder dystocia simulation. Each simulation was scored, based on standardized checklists for 4 technical maneuvers and 6 communication tasks, by 2 physician observers. Paired Student t tests were used for analysis. Forty-three attendings and 28 residents participated. Residents showed significant improvement in mean maneuver (3.3 +/- 0.9 vs 3.9 +/- 0.4, P = .001) and communication (3.5 +/- 1.2 vs 4.9 +/- 1.0, P < .0001) scores after simulation training. Attending physicians' communication (3.6 +/- 1.6 vs 4.9 +/- 1.1, P < .0001) scores were significantly improved after training. Our program improved physician performance in the management of simulated shoulder dystocia deliveries. Obstetric emergency simulation training can improve physicians' communication skills, at all levels of training, and should be incorporated into labor and delivery quality improvement measures.

  4. [Does simulator-based team training improve patient safety?].

    Science.gov (United States)

    Trentzsch, H; Urban, B; Sandmeyer, B; Hammer, T; Strohm, P C; Lazarovici, M

    2013-10-01

    Patient safety became paramount in medicine as well as in emergency medicine after it was recognized that preventable, adverse events significantly contributed to morbidity and mortality during hospital stay. The underlying errors cannot usually be explained by medical technical inadequacies only but are more due to difficulties in the transition of theoretical knowledge into tasks under the conditions of clinical reality. Crew Resource Management and Human Factors which determine safety and efficiency of humans in complex situations are suitable to control such sources of error. Simulation significantly improved safety in high reliability organizations, such as the aerospace industry.Thus, simulator-based team training has also been proposed for medical areas. As such training is consuming in cost, time and human resources, the question of the cost-benefit ratio obviously arises. This review outlines the effects of simulator-based team training on patient safety. Such course formats are not only capable of creating awareness and improvements in safety culture but also improve technical team performance and emphasize team performance as a clinical competence. A few studies even indicated improvement of patient-centered outcome, such as a reduced rate of adverse events but further studies are required in this respect. In summary, simulator-based team training should be accepted as a suitable strategy to improve patient safety.

  5. Airflow Simulation Techniques

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    The paper describes the development in airflow simulations in rooms . The research is, as other areas of flow research, influenced by the decreasing cost of computation which seems to indicate an increased use of airflow simulation in the coming years.......The paper describes the development in airflow simulations in rooms . The research is, as other areas of flow research, influenced by the decreasing cost of computation which seems to indicate an increased use of airflow simulation in the coming years....

  6. Improving the Performance of the Extreme-scale Simulator

    Energy Technology Data Exchange (ETDEWEB)

    Engelmann, Christian [ORNL; Naughton III, Thomas J [ORNL

    2014-01-01

    Investigating the performance of parallel applications at scale on future high-performance computing (HPC) architectures and the performance impact of different architecture choices is an important component of HPC hardware/software co-design. The Extreme-scale Simulator (xSim) is a simulation-based toolkit for investigating the performance of parallel applications at scale. xSim scales to millions of simulated Message Passing Interface (MPI) processes. The overhead introduced by a simulation tool is an important performance and productivity aspect. This paper documents two improvements to xSim: (1) a new deadlock resolution protocol to reduce the parallel discrete event simulation management overhead and (2) a new simulated MPI message matching algorithm to reduce the oversubscription management overhead. The results clearly show a significant performance improvement, such as by reducing the simulation overhead for running the NAS Parallel Benchmark suite inside the simulator from 1,020\\% to 238% for the conjugate gradient (CG) benchmark and from 102% to 0% for the embarrassingly parallel (EP) and benchmark, as well as, from 37,511% to 13,808% for CG and from 3,332% to 204% for EP with accurate process failure simulation.

  7. The new ATLAS Fast Calorimeter Simulation

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00223142; The ATLAS collaboration

    2017-01-01

    Current and future need for large scale simulated samples motivate the development of reliable fast simulation techniques. The new Fast Calorimeter Simulation is an improved parameterized response of single particles in the ATLAS calorimeter that aims to accurately emulate the key features of the detailed calorimeter response as simulated with Geant4, yet approximately ten times faster. Principal component analysis and machine learning techniques are used to improve the performance and decrease the memory need compared to the current version of the ATLAS Fast Calorimeter Simulation. A prototype of this new Fast Calorimeter Simulation is in development and its integration into the ATLAS simulation infrastructure is ongoing.

  8. The new ATLAS Fast Calorimeter Simulation

    Science.gov (United States)

    Schaarschmidt, J.; ATLAS Collaboration

    2017-10-01

    Current and future need for large scale simulated samples motivate the development of reliable fast simulation techniques. The new Fast Calorimeter Simulation is an improved parameterized response of single particles in the ATLAS calorimeter that aims to accurately emulate the key features of the detailed calorimeter response as simulated with Geant4, yet approximately ten times faster. Principal component analysis and machine learning techniques are used to improve the performance and decrease the memory need compared to the current version of the ATLAS Fast Calorimeter Simulation. A prototype of this new Fast Calorimeter Simulation is in development and its integration into the ATLAS simulation infrastructure is ongoing.

  9. Improved haptic interface for colonoscopy simulation.

    Science.gov (United States)

    Woo, Hyun Soo; Kim, Woo Seok; Ahn, Woojin; Lee, Doo Yong; Yi, Sun Young

    2007-01-01

    This paper presents an improved haptic interface of the KAIST-Ewha colonoscopy simulator II. The haptic interface enables the distal portion of the colonoscope to be freely bent while guaranteeing enough workspace and reflective forces for colonoscopy simulation. Its force-torque sensor measures profiles of the user. Manipulation of the colonoscope tip is monitored by four deflection sensors, and triggers computation to render accurate graphic images corresponding to the angle knob rotation. Tack switches are attached on the valve-actuation buttons of the colonoscope to simulate air-injection or suction, and the corresponding deformation of the colon.

  10. An Improved Clutter Suppression Method for Weather Radars Using Multiple Pulse Repetition Time Technique

    Directory of Open Access Journals (Sweden)

    Yingjie Yu

    2017-01-01

    Full Text Available This paper describes the implementation of an improved clutter suppression method for the multiple pulse repetition time (PRT technique based on simulated radar data. The suppression method is constructed using maximum likelihood methodology in time domain and is called parametric time domain method (PTDM. The procedure relies on the assumption that precipitation and clutter signal spectra follow a Gaussian functional form. The multiple interleaved pulse repetition frequencies (PRFs that are used in this work are set to four PRFs (952, 833, 667, and 513 Hz. Based on radar simulation, it is shown that the new method can provide accurate retrieval of Doppler velocity even in the case of strong clutter contamination. The obtained velocity is nearly unbiased for all the range of Nyquist velocity interval. Also, the performance of the method is illustrated on simulated radar data for plan position indicator (PPI scan. Compared with staggered 2-PRT transmission schemes with PTDM, the proposed method presents better estimation accuracy under certain clutter situations.

  11. A NEW TECHNIQUE FOR THE PHOTOSPHERIC DRIVING OF NON-POTENTIAL SOLAR CORONAL MAGNETIC FIELD SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Weinzierl, Marion; Yeates, Anthony R. [Department of Mathematical Sciences, Durham University, South Road, Durham DH1 3LE (United Kingdom); Mackay, Duncan H. [School of Mathematics and Statistics, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS (United Kingdom); Henney, Carl J.; Arge, C. Nick, E-mail: marion.weinzierl@durham.ac.uk [Air Force Research Lab/Space Vehicles Directorate, 3550 Aberdeen Avenue SE, Kirtland AFB, NM (United States)

    2016-05-20

    In this paper, we develop a new technique for driving global non-potential simulations of the Sun’s coronal magnetic field solely from sequences of radial magnetic maps of the solar photosphere. A primary challenge to driving such global simulations is that the required horizontal electric field cannot be uniquely determined from such maps. We show that an “inductive” electric field solution similar to that used by previous authors successfully reproduces specific features of the coronal field evolution in both single and multiple bipole simulations. For these cases, the true solution is known because the electric field was generated from a surface flux-transport model. The match for these cases is further improved by including the non-inductive electric field contribution from surface differential rotation. Then, using this reconstruction method for the electric field, we show that a coronal non-potential simulation can be successfully driven from a sequence of ADAPT maps of the photospheric radial field, without including additional physical observations which are not routinely available.

  12. Selection of productivity improvement techniques via mathematical modeling

    Directory of Open Access Journals (Sweden)

    Mahassan M. Khater

    2011-07-01

    Full Text Available This paper presents a new mathematical model to select an optimal combination of productivity improvement techniques. The proposed model of this paper considers four-stage cycle productivity and the productivity is assumed to be a linear function of fifty four improvement techniques. The proposed model of this paper is implemented for a real-world case study of manufacturing plant. The resulted problem is formulated as a mixed integer programming which can be solved for optimality using traditional methods. The preliminary results of the implementation of the proposed model of this paper indicate that the productivity can be improved through a change on equipments and it can be easily applied for both manufacturing and service industries.

  13. Two dimensional numerical simulation of gas discharges: comparison between particle-in-cell and FCT techniques

    Energy Technology Data Exchange (ETDEWEB)

    Soria-Hoyo, C; Castellanos, A [Departamento de Electronica y Electromagnetismo, Facultad de Fisica, Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012 Sevilla (Spain); Pontiga, F [Departamento de Fisica Aplicada II, EUAT, Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012 Sevilla (Spain)], E-mail: cshoyo@us.es

    2008-10-21

    Two different numerical techniques have been applied to the numerical integration of equations modelling gas discharges: a finite-difference flux corrected transport (FD-FCT) technique and a particle-in-cell (PIC) technique. The PIC technique here implemented has been specifically designed for the simulation of 2D electrical discharges using cylindrical coordinates. The development and propagation of a streamer between two parallel electrodes has been used as a convenient test to compare the performance of both techniques. In particular, the phase velocity of the cathode directed streamer has been used to check the internal consistency of the numerical simulations. The results obtained from the two techniques are in reasonable agreement with each other, and both techniques have proved their ability to follow the high gradients of charge density and electric field present in this type of problems. Moreover, the streamer velocities predicted by the simulation are in accordance with the typical experimental values.

  14. Two dimensional numerical simulation of gas discharges: comparison between particle-in-cell and FCT techniques

    International Nuclear Information System (INIS)

    Soria-Hoyo, C; Castellanos, A; Pontiga, F

    2008-01-01

    Two different numerical techniques have been applied to the numerical integration of equations modelling gas discharges: a finite-difference flux corrected transport (FD-FCT) technique and a particle-in-cell (PIC) technique. The PIC technique here implemented has been specifically designed for the simulation of 2D electrical discharges using cylindrical coordinates. The development and propagation of a streamer between two parallel electrodes has been used as a convenient test to compare the performance of both techniques. In particular, the phase velocity of the cathode directed streamer has been used to check the internal consistency of the numerical simulations. The results obtained from the two techniques are in reasonable agreement with each other, and both techniques have proved their ability to follow the high gradients of charge density and electric field present in this type of problems. Moreover, the streamer velocities predicted by the simulation are in accordance with the typical experimental values.

  15. IMPLEMENTING CONCEPT MAPPING TECHNIQUE TO IMPROVE STUDENTS’ DESCRIPTIVE WRITING ABILITY

    Directory of Open Access Journals (Sweden)

    Rubiyah Rubiyah Rubiyah

    2018-04-01

    Full Text Available This Classroom Action Research aimed at investigating the implementation of Concept Mapping Technique to improve students’ descriptive writing ability. The research was conducted in two cycles at SMP Negeri 21 Samarinda, with 37 seventh grade students participating. In this research, there was one teacher- researcher who implemented the technique and there were two collaborators who did the observation. The data were collected both quantitatively and qualitatively by using writing assessment, interview guide, observation sheets and field notes. The findings showed that: 1 there was an improvement in the students’ descriptive writing average scores at the end of the second research cycle; 2 the implementation of the concept mapping technique was done properly by the teacher- researcher; 3 the concept mapping technique delivered through collaborative working improved the participation of the students in the teaching and learning process. Since all the criteria of success in this research were fulfilled by the end of the second cycle, it could be concluded that this classroom action research was successfully implemented and the technique proposed could very well improve the skills being targeted.

  16. An overview of uncertainty quantification techniques with application to oceanic and oil-spill simulations

    KAUST Repository

    Iskandarani, Mohamed; Wang, Shitao; Srinivasan, Ashwanth; Carlisle Thacker, W.; Winokur, Justin; Knio, Omar

    2016-01-01

    We give an overview of four different ensemble-based techniques for uncertainty quantification and illustrate their application in the context of oil plume simulations. These techniques share the common paradigm of constructing a model proxy that efficiently captures the functional dependence of the model output on uncertain model inputs. This proxy is then used to explore the space of uncertain inputs using a large number of samples, so that reliable estimates of the model's output statistics can be calculated. Three of these techniques use polynomial chaos (PC) expansions to construct the model proxy, but they differ in their approach to determining the expansions' coefficients; the fourth technique uses Gaussian Process Regression (GPR). An integral plume model for simulating the Deepwater Horizon oil-gas blowout provides examples for illustrating the different techniques. A Monte Carlo ensemble of 50,000 model simulations is used for gauging the performance of the different proxies. The examples illustrate how regression-based techniques can outperform projection-based techniques when the model output is noisy. They also demonstrate that robust uncertainty analysis can be performed at a fraction of the cost of the Monte Carlo calculation.

  17. An overview of uncertainty quantification techniques with application to oceanic and oil-spill simulations

    KAUST Repository

    Iskandarani, Mohamed

    2016-04-22

    We give an overview of four different ensemble-based techniques for uncertainty quantification and illustrate their application in the context of oil plume simulations. These techniques share the common paradigm of constructing a model proxy that efficiently captures the functional dependence of the model output on uncertain model inputs. This proxy is then used to explore the space of uncertain inputs using a large number of samples, so that reliable estimates of the model\\'s output statistics can be calculated. Three of these techniques use polynomial chaos (PC) expansions to construct the model proxy, but they differ in their approach to determining the expansions\\' coefficients; the fourth technique uses Gaussian Process Regression (GPR). An integral plume model for simulating the Deepwater Horizon oil-gas blowout provides examples for illustrating the different techniques. A Monte Carlo ensemble of 50,000 model simulations is used for gauging the performance of the different proxies. The examples illustrate how regression-based techniques can outperform projection-based techniques when the model output is noisy. They also demonstrate that robust uncertainty analysis can be performed at a fraction of the cost of the Monte Carlo calculation.

  18. Techniques for the improvement of heat exchange

    International Nuclear Information System (INIS)

    Huyghe, J.

    1983-01-01

    The target of the described techniques is either to improve the performances of the equipements or to reduce their cost price. These techniques were developed at the laboratory scale and some of them were tested in pilot units. Neither of them has yet been applied in commercial plants. Different type of corrogated tubes, thin film evaporation, dropwise condensation, plastic tube or plates, tube configuration and heat pipes are examined [fr

  19. Application of the PRBS/FFT technique to digital simulations

    International Nuclear Information System (INIS)

    Hinds, H.W.

    1977-01-01

    This paper describes a method for obtaining a small-signal frequency response from a digital dynamic simulation. It employs a modified form of the PRBS/FFT technique, whereby a system is perturbed by a pseudo-random binary sequence and its response is analyzed using a fast Fourier transform-based program. Two applications of the technique are described; one involves a set of two coupled, second-order, ordinary differential equations; the other is a set of non-linear partial differential equations describing the thermohydraulic behaviour of water boiling in a fuel channel. (author)

  20. A New Multiscale Technique for Time-Accurate Geophysics Simulations

    Science.gov (United States)

    Omelchenko, Y. A.; Karimabadi, H.

    2006-12-01

    Large-scale geophysics systems are frequently described by multiscale reactive flow models (e.g., wildfire and climate models, multiphase flows in porous rocks, etc.). Accurate and robust simulations of such systems by traditional time-stepping techniques face a formidable computational challenge. Explicit time integration suffers from global (CFL and accuracy) timestep restrictions due to inhomogeneous convective and diffusion processes, as well as closely coupled physical and chemical reactions. Application of adaptive mesh refinement (AMR) to such systems may not be always sufficient since its success critically depends on a careful choice of domain refinement strategy. On the other hand, implicit and timestep-splitting integrations may result in a considerable loss of accuracy when fast transients in the solution become important. To address this issue, we developed an alternative explicit approach to time-accurate integration of such systems: Discrete-Event Simulation (DES). DES enables asynchronous computation by automatically adjusting the CPU resources in accordance with local timescales. This is done by encapsulating flux- conservative updates of numerical variables in the form of events, whose execution and synchronization is explicitly controlled by imposing accuracy and causality constraints. As a result, at each time step DES self- adaptively updates only a fraction of the global system state, which eliminates unnecessary computation of inactive elements. DES can be naturally combined with various mesh generation techniques. The event-driven paradigm results in robust and fast simulation codes, which can be efficiently parallelized via a new preemptive event processing (PEP) technique. We discuss applications of this novel technology to time-dependent diffusion-advection-reaction and CFD models representative of various geophysics applications.

  1. Validation techniques of agent based modelling for geospatial simulations

    Directory of Open Access Journals (Sweden)

    M. Darvishi

    2014-10-01

    Full Text Available One of the most interesting aspects of modelling and simulation study is to describe the real world phenomena that have specific properties; especially those that are in large scales and have dynamic and complex behaviours. Studying these phenomena in the laboratory is costly and in most cases it is impossible. Therefore, Miniaturization of world phenomena in the framework of a model in order to simulate the real phenomena is a reasonable and scientific approach to understand the world. Agent-based modelling and simulation (ABMS is a new modelling method comprising of multiple interacting agent. They have been used in the different areas; for instance, geographic information system (GIS, biology, economics, social science and computer science. The emergence of ABM toolkits in GIS software libraries (e.g. ESRI’s ArcGIS, OpenMap, GeoTools, etc for geospatial modelling is an indication of the growing interest of users to use of special capabilities of ABMS. Since ABMS is inherently similar to human cognition, therefore it could be built easily and applicable to wide range applications than a traditional simulation. But a key challenge about ABMS is difficulty in their validation and verification. Because of frequent emergence patterns, strong dynamics in the system and the complex nature of ABMS, it is hard to validate and verify ABMS by conventional validation methods. Therefore, attempt to find appropriate validation techniques for ABM seems to be necessary. In this paper, after reviewing on Principles and Concepts of ABM for and its applications, the validation techniques and challenges of ABM validation are discussed.

  2. Validation techniques of agent based modelling for geospatial simulations

    Science.gov (United States)

    Darvishi, M.; Ahmadi, G.

    2014-10-01

    One of the most interesting aspects of modelling and simulation study is to describe the real world phenomena that have specific properties; especially those that are in large scales and have dynamic and complex behaviours. Studying these phenomena in the laboratory is costly and in most cases it is impossible. Therefore, Miniaturization of world phenomena in the framework of a model in order to simulate the real phenomena is a reasonable and scientific approach to understand the world. Agent-based modelling and simulation (ABMS) is a new modelling method comprising of multiple interacting agent. They have been used in the different areas; for instance, geographic information system (GIS), biology, economics, social science and computer science. The emergence of ABM toolkits in GIS software libraries (e.g. ESRI's ArcGIS, OpenMap, GeoTools, etc) for geospatial modelling is an indication of the growing interest of users to use of special capabilities of ABMS. Since ABMS is inherently similar to human cognition, therefore it could be built easily and applicable to wide range applications than a traditional simulation. But a key challenge about ABMS is difficulty in their validation and verification. Because of frequent emergence patterns, strong dynamics in the system and the complex nature of ABMS, it is hard to validate and verify ABMS by conventional validation methods. Therefore, attempt to find appropriate validation techniques for ABM seems to be necessary. In this paper, after reviewing on Principles and Concepts of ABM for and its applications, the validation techniques and challenges of ABM validation are discussed.

  3. Statistical learning techniques applied to epidemiology: a simulated case-control comparison study with logistic regression

    Directory of Open Access Journals (Sweden)

    Land Walker H

    2011-01-01

    Full Text Available Abstract Background When investigating covariate interactions and group associations with standard regression analyses, the relationship between the response variable and exposure may be difficult to characterize. When the relationship is nonlinear, linear modeling techniques do not capture the nonlinear information content. Statistical learning (SL techniques with kernels are capable of addressing nonlinear problems without making parametric assumptions. However, these techniques do not produce findings relevant for epidemiologic interpretations. A simulated case-control study was used to contrast the information embedding characteristics and separation boundaries produced by a specific SL technique with logistic regression (LR modeling representing a parametric approach. The SL technique was comprised of a kernel mapping in combination with a perceptron neural network. Because the LR model has an important epidemiologic interpretation, the SL method was modified to produce the analogous interpretation and generate odds ratios for comparison. Results The SL approach is capable of generating odds ratios for main effects and risk factor interactions that better capture nonlinear relationships between exposure variables and outcome in comparison with LR. Conclusions The integration of SL methods in epidemiology may improve both the understanding and interpretation of complex exposure/disease relationships.

  4. Simulation of wind turbine wakes using the actuator line technique

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming; Henningson, Dan S.

    2015-01-01

    The actuator line technique was introduced as a numerical tool to be employed in combination with large eddy simulations to enable the study of wakes and wake interaction in wind farms. The technique is today largely used for studying basic features of wakes as well as for making performance...... predictions of wind farms. In this paper, we give a short introduction to the wake problem and the actuator line methodology and present a study in which the technique is employed to determine the near-wake properties of wind turbines. The presented results include a comparison of experimental results...

  5. Reduction of radiation-induced xerostomia in nasopharyngeal carcinoma using CT simulation with laser patient marking and three-field irradiation technique

    International Nuclear Information System (INIS)

    Nishioka, Takeshi; Shirato, Hiroki; Arimoto, Takuro; Kaneko, Masanori; Kitahara, Toshihiro; Oomori, Keiichi; Yasuda, Motoyuki; Fukuda, Satoshi; Inuyama, Yukio; Miyasaka, Kazuo

    1997-01-01

    Purpose: Tumor control and reduction of postirradiation xerostomia in patients with nasopharyngeal carcinoma (NPC) using the three-field irradiation technique based on the CT-based simulation with laser patient marking was investigated. Methods and Materials: Seventy-eight patients with NPC were consecutively treated between 1983 and 1993. In 33 patients treated before 1987, target volume was determined using a conventional x-ray simulator with a reference of CT images, and the primary site was treated by the conventional parallel-opposed two-field technique (Group I). In 45 patients treated from 1987, target volume was determined using a CT simulator slice by slice, the treatment field was projected onto the patient's skin by a laser beam projector mounted on a C-arm, and the primary site was irradiated by a three-fields (anterior and bilateral) technique (Group II). In Group II, the shape of each field was determined using a beam's eye view to reduce the dose to the bilateral parotid glands. The three-field technique reduced the dose to the superficial lobe of parotid gland to about two-thirds of the dose given by the two-field technique. Radiation-induced xerostomia was evaluated by clinical symptoms and radio-isotope sialography. Results: The 5-year survival rate and disease-free survival rate were 46.6 and 31.2% in Group I, and 46.8 and 46.5% in Group II. A large variation in the volume of parotid glands were demonstrated, ranging from 9 cm 3 to 61 cm 3 among patients treated with CT simulation. Forty percent of the patients in Group II showed no or mild xerostomia, whereas all of the patients in Group I showed moderate to severe xerostomia (p < 0.01). The radioisotope sialography study showed that the mean secretion ratio by acid stimulation was improved from 3.8% in the Group I to 15.2% in the Group II (p < 0.01). Conclusions: CT simulation was useful to determine the size and shape of each field to reduce the dose to the parotid gland, of which size varies

  6. Improving the performance of a filling line based on simulation

    Science.gov (United States)

    Jasiulewicz-Kaczmarek, M.; Bartkowiak, T.

    2016-08-01

    The paper describes the method of improving performance of a filling line based on simulation. This study concerns a production line that is located in a manufacturing centre of a FMCG company. A discrete event simulation model was built using data provided by maintenance data acquisition system. Two types of failures were identified in the system and were approximated using continuous statistical distributions. The model was validated taking into consideration line performance measures. A brief Pareto analysis of line failures was conducted to identify potential areas of improvement. Two improvements scenarios were proposed and tested via simulation. The outcome of the simulations were the bases of financial analysis. NPV and ROI values were calculated taking into account depreciation, profits, losses, current CIT rate and inflation. A validated simulation model can be a useful tool in maintenance decision-making process.

  7. IMPROVING TACONITE PROCESSING PLANT EFFICIENCY BY COMPUTER SIMULATION, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    William M. Bond; Salih Ersayin

    2007-03-30

    This project involved industrial scale testing of a mineral processing simulator to improve the efficiency of a taconite processing plant, namely the Minorca mine. The Concentrator Modeling Center at the Coleraine Minerals Research Laboratory, University of Minnesota Duluth, enhanced the capabilities of available software, Usim Pac, by developing mathematical models needed for accurate simulation of taconite plants. This project provided funding for this technology to prove itself in the industrial environment. As the first step, data representing existing plant conditions were collected by sampling and sample analysis. Data were then balanced and provided a basis for assessing the efficiency of individual devices and the plant, and also for performing simulations aimed at improving plant efficiency. Performance evaluation served as a guide in developing alternative process strategies for more efficient production. A large number of computer simulations were then performed to quantify the benefits and effects of implementing these alternative schemes. Modification of makeup ball size was selected as the most feasible option for the target performance improvement. This was combined with replacement of existing hydrocyclones with more efficient ones. After plant implementation of these modifications, plant sampling surveys were carried out to validate findings of the simulation-based study. Plant data showed very good agreement with the simulated data, confirming results of simulation. After the implementation of modifications in the plant, several upstream bottlenecks became visible. Despite these bottlenecks limiting full capacity, concentrator energy improvement of 7% was obtained. Further improvements in energy efficiency are expected in the near future. The success of this project demonstrated the feasibility of a simulation-based approach. Currently, the Center provides simulation-based service to all the iron ore mining companies operating in northern

  8. Loading pattern optimization by multi-objective simulated annealing with screening technique

    International Nuclear Information System (INIS)

    Tong, K. P.; Hyun, C. L.; Hyung, K. J.; Chang, H. K.

    2006-01-01

    This paper presents a new multi-objective function which is made up of the main objective term as well as penalty terms related to the constraints. All the terms are represented in the same functional form and the coefficient of each term is normalized so that each term has equal weighting in the subsequent simulated annealing optimization calculations. The screening technique introduced in the previous work is also adopted in order to save computer time in 3-D neutronics evaluation of trial loading patterns. For numerical test of the new multi-objective function in the loading pattern optimization, the optimum loading patterns for the initial and the cycle 7 reload PWR core of Yonggwang Unit 4 are calculated by the simulated annealing algorithm with screening technique. A total of 10 optimum loading patterns are obtained for the initial core through 10 independent simulated annealing optimization runs. For the cycle 7 reload core one optimum loading pattern has been obtained from a single simulated annealing optimization run. More SA optimization runs will be conducted to optimum loading patterns for the cycle 7 reload core and results will be presented in the further work. (authors)

  9. Innovations in surgery simulation: a review of past, current and future techniques.

    Science.gov (United States)

    Badash, Ido; Burtt, Karen; Solorzano, Carlos A; Carey, Joseph N

    2016-12-01

    As a result of recent work-hours limitations and concerns for patient safety, innovations in extraclinical surgical simulation have become a desired part of residency education. Current simulation models, including cadaveric, animal, bench-top, virtual reality (VR) and robotic simulators are increasingly used in surgical training programs. Advances in telesurgery, three-dimensional (3D) printing, and the incorporation of patient-specific anatomy are paving the way for simulators to become integral components of medical training in the future. Evidence from the literature highlights the benefits of including simulations in surgical training; skills acquired through simulations translate into improvements in operating room performance. Moreover, simulations are rapidly incorporating new medical technologies and offer increasingly high-fidelity recreations of procedures. As a result, both novice and expert surgeons are able to benefit from their use. As dedicated, structured curricula are developed that incorporate simulations into daily resident training, simulated surgeries will strengthen the surgeon's skill set, decrease hospital costs, and improve patient outcomes.

  10. Teaching aseptic technique for central venous access under ultrasound guidance: a randomized trial comparing didactic training alone to didactic plus simulation-based training.

    Science.gov (United States)

    Latif, Rana K; Bautista, Alexander F; Memon, Saima B; Smith, Elizabeth A; Wang, Chenxi; Wadhwa, Anupama; Carter, Mary B; Akca, Ozan

    2012-03-01

    Our goal was to determine whether simulation combined with didactic training improves sterile technique during ultrasound (US)-guided central venous catheter (CVC) insertion compared with didactic training alone among novices. We hypothesized that novices who receive combined didactic and simulation-based training would perform similarly to experienced residents in aseptic technique, knowledge, and perception of comfort during US-guided CVC insertion on a simulator. Seventy-two subjects were enrolled in a randomized, controlled trial of an educational intervention. Fifty-four novices were randomized into either the didactic group or the simulation combined with didactic group. Both groups received didactic training but the simulation combined with didactic group also received simulation-based CVC insertion training. Both groups were tested by demonstrating US-guided CVC insertion on a simulator. Aseptic technique was scored on 8 steps as "yes/no" and also using a 7-point Likert scale with 7 being "excellent technique" by a rater blinded to subject randomization. After initial testing, the didactic group was offered simulation-based training and retesting. Both groups also took a pre- and posttraining test of knowledge and rated their comfort with US and CVC insertion pre- and posttraining on a 5-point Likert scale. Subsequently, 18 experienced residents also took the test of knowledge, rated their comfort level, and were scored while performing aseptic US-guided CVC insertion using a simulator. The simulation combined with didactic group achieved a 167% (95% confidence interval [CI] 133%-167%) incremental increase in yes/no scores and 115% (CI 112%-127%) incremental increase in Likert scale ratings on aseptic technique compared with novices in the didactic group. Compared with experienced residents, simulation combined with didactic trained novices achieved an increase in aseptic scores with a 33.3% (CI 16.7%-50%) increase in yes/no ratings and a 20% (CI 13

  11. Simulation of the fissureless technique for thoracoscopic segmentectomy using rapid prototyping.

    Science.gov (United States)

    Akiba, Tadashi; Nakada, Takeo; Inagaki, Takuya

    2015-01-01

    The fissureless lobectomy or anterior fissureless technique is a novel surgical technique, which avoids dissection of the lung parenchyma over the pulmonary artery during lobectomy by open thoracotomy approach or direct vision thoracoscopic surgery. This technique is indicated for fused lobes. We present two cases where thoracoscopic pulmonary segmentectomy was performed using the fissureless technique simulated by three-dimensional (3D) pulmonary models. The 3D model and rapid prototyping provided an accurate anatomical understanding of the operative field in both cases. We believe that the construction of these models is useful for thoracoscopic and other complicated surgeries of the chest.

  12. Simulation of the Fissureless Technique for Thoracoscopic Segmentectomy Using Rapid Prototyping

    Science.gov (United States)

    Nakada, Takeo; Inagaki, Takuya

    2014-01-01

    The fissureless lobectomy or anterior fissureless technique is a novel surgical technique, which avoids dissection of the lung parenchyma over the pulmonary artery during lobectomy by open thoracotomy approach or direct vision thoracoscopic surgery. This technique is indicated for fused lobes. We present two cases where thoracoscopic pulmonary segmentectomy was performed using the fissureless technique simulated by three-dimensional (3D) pulmonary models. The 3D model and rapid prototyping provided an accurate anatomical understanding of the operative field in both cases. We believe that the construction of these models is useful for thoracoscopic and other complicated surgeries of the chest. PMID:24633132

  13. On Improving 4-km Mesoscale Model Simulations

    Science.gov (United States)

    Deng, Aijun; Stauffer, David R.

    2006-03-01

    A previous study showed that use of analysis-nudging four-dimensional data assimilation (FDDA) and improved physics in the fifth-generation Pennsylvania State University National Center for Atmospheric Research Mesoscale Model (MM5) produced the best overall performance on a 12-km-domain simulation, based on the 18 19 September 1983 Cross-Appalachian Tracer Experiment (CAPTEX) case. However, reducing the simulated grid length to 4 km had detrimental effects. The primary cause was likely the explicit representation of convection accompanying a cold-frontal system. Because no convective parameterization scheme (CPS) was used, the convective updrafts were forced on coarser-than-realistic scales, and the rainfall and the atmospheric response to the convection were too strong. The evaporative cooling and downdrafts were too vigorous, causing widespread disruption of the low-level winds and spurious advection of the simulated tracer. In this study, a series of experiments was designed to address this general problem involving 4-km model precipitation and gridpoint storms and associated model sensitivities to the use of FDDA, planetary boundary layer (PBL) turbulence physics, grid-explicit microphysics, a CPS, and enhanced horizontal diffusion. Some of the conclusions include the following: 1) Enhanced parameterized vertical mixing in the turbulent kinetic energy (TKE) turbulence scheme has shown marked improvements in the simulated fields. 2) Use of a CPS on the 4-km grid improved the precipitation and low-level wind results. 3) Use of the Hong and Pan Medium-Range Forecast PBL scheme showed larger model errors within the PBL and a clear tendency to predict much deeper PBL heights than the TKE scheme. 4) Combining observation-nudging FDDA with a CPS produced the best overall simulations. 5) Finer horizontal resolution does not always produce better simulations, especially in convectively unstable environments, and a new CPS suitable for 4-km resolution is needed. 6

  14. Improvement of nuclear ship engineering simulation system. Hardware renewal and interface improvement of the integral type reactor

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroki; Kyoya, Masahiko; Shimazaki, Junya [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kano, Tadashi [KCS, Co., Mito, Ibaraki (Japan); Takahashi, Teruo [Energis, Co., Kobe, Hyogo (Japan)

    2001-10-01

    JAERI had carried out the design study about a lightweight and compact integral type reactor (an advanced marine reactor) with passive safety equipment as a power source for the future nuclear ships, and completed an engineering design. We have developed the simulator for the integral type reactor to confirm the design and operation performance and to utilize the study of automation of the reactor operation. The simulator can be used also for future research and development of a compact reactor. However, the improvement in a performance of hardware and a human machine interface of software of the simulator were needed for future research and development. Therefore, renewal of hardware and improvement of software have been conducted. The operability of the integral-reactor simulator has been improved. Furthermore, this improvement with the hardware and software on the market brought about better versatility, maintainability, extendibility and transfer of the system. This report mainly focuses on contents of the enhancement in a human machine interface, and describes hardware renewal and the interface improvement of the integral type reactor simulator. (author)

  15. Practice on an augmented reality/haptic simulator and library of virtual brains improves residents' ability to perform a ventriculostomy.

    Science.gov (United States)

    Yudkowsky, Rachel; Luciano, Cristian; Banerjee, Pat; Schwartz, Alan; Alaraj, Ali; Lemole, G Michael; Charbel, Fady; Smith, Kelly; Rizzi, Silvio; Byrne, Richard; Bendok, Bernard; Frim, David

    2013-02-01

    Ventriculostomy is a neurosurgical procedure for providing therapeutic cerebrospinal fluid drainage. Complications may arise during repeated attempts at placing the catheter in the ventricle. We studied the impact of simulation-based practice with a library of virtual brains on neurosurgery residents' performance in simulated and live surgical ventriculostomies. Using computed tomographic scans of actual patients, we developed a library of 15 virtual brains for the ImmersiveTouch system, a head- and hand-tracked augmented reality and haptic simulator. The virtual brains represent a range of anatomies including normal, shifted, and compressed ventricles. Neurosurgery residents participated in individual simulator practice on the library of brains including visualizing the 3-dimensional location of the catheter within the brain immediately after each insertion. Performance of participants on novel brains in the simulator and during actual surgery before and after intervention was analyzed using generalized linear mixed models. Simulator cannulation success rates increased after intervention, and live procedure outcomes showed improvement in the rate of successful cannulation on the first pass. However, the incidence of deeper, contralateral (simulator) and third-ventricle (live) placements increased after intervention. Residents reported that simulations were realistic and helpful in improving procedural skills such as aiming the probe, sensing the pressure change when entering the ventricle, and estimating how far the catheter should be advanced within the ventricle. Simulator practice with a library of virtual brains representing a range of anatomies and difficulty levels may improve performance, potentially decreasing complications due to inexpert technique.

  16. Improvement of the NSSS T/H Module for Enhancing the Simulation Fidelity of KNPEC-2 Simulator

    International Nuclear Information System (INIS)

    Kim, Kyung Doo; Lee, Seung Wook; Jeong, Jae Jun; Lee, Myung Soo

    2005-01-01

    KEPRI(Korea Electric Power Research Institute) and KAERI (Korea Atomic Energy Research Institute) jointly developed and supplied a realistic NSSS (Nuclear Steam Supply System) T/H (Thermal-Hydraulic) module (named ARTS) based on the best-estimate code RETRAN-3D for the improvement of the KNPEC-2 full-scope simulator in 2001. Although ARTS can simulate the most transients in real-time, and its robustness is ensured, real-time calculation and robustness can fail for largebreak (LB) loss-of-coolant accident (LOCA) and longterm, two-phase transients. In order to improve its robustness, ARTS equipped with the backup calculation module to be used whenever a regular ARTS module fails to calculate. When the symptom for the failure of T/H module is detected, the main ARTS module is replaced with the backup module for the calculation of primary and secondary reactor system although most failures of ARTS occur in the calculation of the primary system especially for LB LOCA simulation. The sudden transition from the main ARTS module to the backup module can exhibit the discontinuity of simulation of secondary system on rare occasions. To mitigate the simulation discontinuity, we have improved the backup module of ARTS. The performance of a new approach has been illustrated by the non-integrated standalone test. The improved ARTS module will be incorporated into KNPEC-2 simulator and evaluated its performance in the real simulator environment. This paper presents the brief description of a new backup calculation strategy and the simulation results of LOCA to evaluate the performance of a new backup strategy in standalone test environment

  17. Improving the fidelity of electrically heated nuclear systems testing using simulated neutronic feedback

    International Nuclear Information System (INIS)

    Bragg-Sitton, Shannon M.; Godfroy, Thomas J.; Webster, Kenny

    2010-01-01

    Nonnuclear test platforms and methodologies can be employed to reduce the overall cost, risk and complexity of testing nuclear systems while allowing one to evaluate the operation of an integrated nuclear system within a reasonable timeframe, providing valuable input to the overall system design. In a nonnuclear test bed, electric heaters are used to simulate the heat from nuclear fuel. Standard electric test techniques allow one to fully assess thermal, heat transfer, and stress related attributes of a given system, but these approaches fail to demonstrate the dynamic response that would be present in an integrated, fueled reactor system. The integration of thermal hydraulic hardware tests with simulated neutronic response provides a bridge between electrically heated testing and testing with nuclear fuel elements installed. By implementing a neutronic response model to simulate the dynamic response that would be expected in a fueled reactor system, one can better understand system integration issues, characterize integrated system response times and response characteristics, and assess potential design improvements at a relatively small fiscal investment. This paper summarizes the results of initial system dynamic response testing for two electrically heated reactor concepts: a heat pipe-cooled reactor simulator with integrated heat exchanger and a gas-cooled reactor simulator with integrated Brayton power conversion system. Initial applications apply a simplified reactor kinetics model with either a single or an averaged measured state point. Preliminary results demonstrate the applicability of the dynamic test methodology to any reactor type, elucidating the variation in system response characteristics in different reactor concepts. These results suggest a need to further enhance the dynamic test approach by incorporating a more accurate model of the reactor dynamics and improved hardware instrumentation for better state estimation in application of the

  18. Improving animal productivity by nuclear techniques

    International Nuclear Information System (INIS)

    Garcia, M.; Jayasuriya, M.C.N.; Perera, B.M.A.O.

    1995-01-01

    The IAEA and FAO have run a joint programme for 30 years to assist national agricultural research systems in member states to develop, test and apply nuclear and related techniques for improving the productivity of livestock. Applications of nuclear technologies for improving livestock productivity include: use of radioimmunoassay in animal nutrition researches, animal production, and evaluating feeding and management systems through reproductive performance in a field. Geographic coverage and the type of livestock studies are: grazing animals (cattle, goats and sheep) in Africa, Latin America and Asia, as well as buffalo production in Asia. 6 refs, 8 figs, 6 tabs

  19. Improved Image Encryption for Real-Time Application over Wireless Communication Networks using Hybrid Cryptography Technique

    Directory of Open Access Journals (Sweden)

    Kazeem B. Adedeji

    2016-12-01

    Full Text Available Advances in communication networks have enabled organization to send confidential data such as digital images over wireless networks. However, the broadcast nature of wireless communication channel has made it vulnerable to attack from eavesdroppers. We have developed a hybrid cryptography technique, and we present its application to digital images as a means of improving the security of digital image for transmission over wireless communication networks. The hybrid technique uses a combination of a symmetric (Data Encryption Standard and asymmetric (Rivest Shamir Adleman cryptographic algorithms to secure data to be transmitted between different nodes of a wireless network. Three different image samples of type jpeg, png and jpg were tested using this technique. The results obtained showed that the hybrid system encrypt the images with minimal simulation time, and high throughput. More importantly, there is no relation or information between the original images and their encrypted form, according to Shannon’s definition of perfect security, thereby making the system much more secure.

  20. Improving neuromodulation technique for refractory voiding dysfunctions: two-stage implant.

    Science.gov (United States)

    Janknegt, R A; Weil, E H; Eerdmans, P H

    1997-03-01

    Neuromodulation is a new technique that uses electrical stimulation of the sacral nerves for patients with refractory urinary urge/frequency or urge-incontinence, and some forms of urinary retention. The limiting factor for receiving an implant is often a failure of the percutaneous nerve evaluation (PNE) test. Present publications mention only about a 50% success score for PNE of all patients, although the micturition diaries and urodynamic parameters are similar. We wanted to investigate whether PNE results improved by using a permanent electrode as a PNE test. This would show that improvement of the PNE technique is feasible. In 10 patients where the original PNE had failed to improve the micturition diary parameters more than 50%, a permanent electrode was implanted by operation. It was connected to an external stimulator. In those cases where the patients improved according to their micturition diary by more than 50% during a period of 4 days, the external stimulator was replaced by a permanent subcutaneous neurostimulator. Eight of the 10 patients had a good to very good result (60% to 90% improvement) during the testing period and received their implant 5 to 14 days after the first stage. The good results of the two-stage implant technique we used indicate that the development of better PNE electrodes may lead to an improvement of the testing technique and better selection between nonresponders and technical failures.

  1. Analytical vs. Simulation Solution Techniques for Pulse Problems in Non-linear Stochastic Dynamics

    DEFF Research Database (Denmark)

    Iwankiewicz, R.; Nielsen, Søren R. K.

    Advantages and disadvantages of available analytical and simulation techniques for pulse problems in non-linear stochastic dynamics are discussed. First, random pulse problems, both those which do and do not lead to Markov theory, are presented. Next, the analytical and analytically-numerical tec......Advantages and disadvantages of available analytical and simulation techniques for pulse problems in non-linear stochastic dynamics are discussed. First, random pulse problems, both those which do and do not lead to Markov theory, are presented. Next, the analytical and analytically...

  2. Improving surgeon utilization in an orthopedic department using simulation modeling

    Directory of Open Access Journals (Sweden)

    Simwita YW

    2016-10-01

    Full Text Available Yusta W Simwita, Berit I Helgheim Department of Logistics, Molde University College, Molde, Norway Purpose: Worldwide more than two billion people lack appropriate access to surgical services due to mismatch between existing human resource and patient demands. Improving utilization of existing workforce capacity can reduce the existing gap between surgical demand and available workforce capacity. In this paper, the authors use discrete event simulation to explore the care process at an orthopedic department. Our main focus is improving utilization of surgeons while minimizing patient wait time.Methods: The authors collaborated with orthopedic department personnel to map the current operations of orthopedic care process in order to identify factors that influence poor surgeons utilization and high patient waiting time. The authors used an observational approach to collect data. The developed model was validated by comparing the simulation output with the actual patient data that were collected from the studied orthopedic care process. The authors developed a proposal scenario to show how to improve surgeon utilization.Results: The simulation results showed that if ancillary services could be performed before the start of clinic examination services, the orthopedic care process could be highly improved. That is, improved surgeon utilization and reduced patient waiting time. Simulation results demonstrate that with improved surgeon utilizations, up to 55% increase of future demand can be accommodated without patients reaching current waiting time at this clinic, thus, improving patient access to health care services.Conclusion: This study shows how simulation modeling can be used to improve health care processes. This study was limited to a single care process; however the findings can be applied to improve other orthopedic care process with similar operational characteristics. Keywords: waiting time, patient, health care process

  3. Parallel Reservoir Simulations with Sparse Grid Techniques and Applications to Wormhole Propagation

    KAUST Repository

    Wu, Yuanqing

    2015-09-08

    In this work, two topics of reservoir simulations are discussed. The first topic is the two-phase compositional flow simulation in hydrocarbon reservoir. The major obstacle that impedes the applicability of the simulation code is the long run time of the simulation procedure, and thus speeding up the simulation code is necessary. Two means are demonstrated to address the problem: parallelism in physical space and the application of sparse grids in parameter space. The parallel code can gain satisfactory scalability, and the sparse grids can remove the bottleneck of flash calculations. Instead of carrying out the flash calculation in each time step of the simulation, a sparse grid approximation of all possible results of the flash calculation is generated before the simulation. Then the constructed surrogate model is evaluated to approximate the flash calculation results during the simulation. The second topic is the wormhole propagation simulation in carbonate reservoir. In this work, different from the traditional simulation technique relying on the Darcy framework, we propose a new framework called Darcy-Brinkman-Forchheimer framework to simulate wormhole propagation. Furthermore, to process the large quantity of cells in the simulation grid and shorten the long simulation time of the traditional serial code, standard domain-based parallelism is employed, using the Hypre multigrid library. In addition to that, a new technique called “experimenting field approach” to set coefficients in the model equations is introduced. In the 2D dissolution experiments, different configurations of wormholes and a series of properties simulated by both frameworks are compared. We conclude that the numerical results of the DBF framework are more like wormholes and more stable than the Darcy framework, which is a demonstration of the advantages of the DBF framework. The scalability of the parallel code is also evaluated, and good scalability can be achieved. Finally, a mixed

  4. IMPROVING STUDENTS’ WRITING ABILITY THROUGH CUE CARDS TECHNIQUE

    Directory of Open Access Journals (Sweden)

    Fenny Thresia

    2017-05-01

    Full Text Available This research is a qualitative research with two variables. The classroom action research is conducted at phisics study program of Muhammadiyah University of Metro. The subject of this research is first semester students of physics study program. The number of the students is 22. The objective of this research was to know how cue cards technique improve the students’ writing ability in descriptive text. The researcher choose one class because they have problem in writing ability. This research was conducted in two cycles. Each cycle consisted of planning, acting, observing and reflecting. The data were collected from test (pre test and post test, observation. The result of this research can be seen from the average score of pre test (before treatment was 61,86, in cycle 1 was 70,90 and in post test cycle 2 was 78. That was involved in upgrading maximally. It implied that cue cards technique can improve the students writing ability in descriptive text. In other words, the class had fulfilled criteria success of standard students competency from the school.It was supported by the observation of the students. From the result of the discussion, the researcher concludes that in this research there is an improvement student writing ability in descriptive text using cue cards technique at the students of physics academic year 2015/2016. Key Words : Descriptive Text, Writing Ability, Cue Cards Technique

  5. Simulation into Reality: Some Effects of Simulation Techniques on Organizational Communication Students.

    Science.gov (United States)

    Allen, Richard K.

    In an attempt to discover improved classroom teaching methods, a class was turned into a business organization as a way of bringing life to the previously covered lectures and textual materials. The simulated games were an attempt to get people to work toward a common goal with all of the power plays, secret meetings, brainstorming, anger, and…

  6. Nuclear fuel cycle cost analysis using a probabilistic simulation technique

    International Nuclear Information System (INIS)

    Won, Il Ko; Jong, Won Choi; Chul, Hyung Kang; Jae, Sol Lee; Kun, Jai Lee

    1998-01-01

    A simple approach was described to incorporate the Monte Carlo simulation technique into a fuel cycle cost estimate. As a case study, the once-through and recycle fuel cycle options were tested with some alternatives (ie. the change of distribution type for input parameters), and the simulation results were compared with the values calculated by a deterministic method. A three-estimate approach was used for converting cost inputs into the statistical parameters of assumed probabilistic distributions. It was indicated that the Monte Carlo simulation by a Latin Hypercube Sampling technique and subsequent sensitivity analyses were useful for examining uncertainty propagation of fuel cycle costs, and could more efficiently provide information to decisions makers than a deterministic method. It was shown from the change of distribution types of input parameters that the values calculated by the deterministic method were set around a 40 th ∼ 50 th percentile of the output distribution function calculated by probabilistic simulation. Assuming lognormal distribution of inputs, however, the values calculated by the deterministic method were set around an 85 th percentile of the output distribution function calculated by probabilistic simulation. It was also indicated from the results of the sensitivity analysis that the front-end components were generally more sensitive than the back-end components, of which the uranium purchase cost was the most important factor of all. It showed, also, that the discount rate made many contributions to the fuel cycle cost, showing the rank of third or fifth of all components. The results of this study could be useful in applications to another options, such as the Dcp (Direct Use of PWR spent fuel In Candu reactors) cycle with high cost uncertainty

  7. Simulation techniques for spatially evolving instabilities in compressible flow over a flat plate

    NARCIS (Netherlands)

    Wasistho, B.; Geurts, Bernardus J.; Kuerten, Johannes G.M.

    1997-01-01

    In this paper we present numerical techniques suitable for a direct numerical simulation in the spatial setting. We demonstrate the application to the simulation of compressible flat plate flow instabilities. We compare second and fourth order accurate spatial discretization schemes in combination

  8. An improved technique for breast cancer irradiation including the locoregional lymph nodes

    NARCIS (Netherlands)

    Hurkmans, C. W.; Saarnak, A. E.; Pieters, B. R.; Borger, J. H.; Bruinvis, I. A.

    2000-01-01

    PURPOSE: To find an irradiation technique for locoregional irradiation of breast cancer patients which, compared with a standard technique, improves the dose distribution to the internal mammary-medial supraclavicular (IM-MS) lymph nodes. The improved technique is intended to minimize the lung dose

  9. Numerical Simulation of Antennas with Improved Integral Equation Method

    International Nuclear Information System (INIS)

    Ma Ji; Fang Guang-You; Lu Wei

    2015-01-01

    Simulating antennas around a conducting object is a challenge task in computational electromagnetism, which is concerned with the behaviour of electromagnetic fields. To analyze this model efficiently, an improved integral equation-fast Fourier transform (IE-FFT) algorithm is presented in this paper. The proposed scheme employs two Cartesian grids with different size and location to enclose the antenna and the other object, respectively. On the one hand, IE-FFT technique is used to store matrix in a sparse form and accelerate the matrix-vector multiplication for each sub-domain independently. On the other hand, the mutual interaction between sub-domains is taken as the additional exciting voltage in each matrix equation. By updating integral equations several times, the whole electromagnetic system can achieve a stable status. Finally, the validity of the presented method is verified through the analysis of typical antennas in the presence of a conducting object. (paper)

  10. Enamel dose calculation by electron paramagnetic resonance spectral simulation technique

    International Nuclear Information System (INIS)

    Dong Guofu; Cong Jianbo; Guo Linchao; Ning Jing; Xian Hong; Wang Changzhen; Wu Ke

    2011-01-01

    Objective: To optimize the enamel electron paramagnetic resonance (EPR) spectral processing by using the EPR spectral simulation method to improve the accuracy of enamel EPR dosimetry and reduce artificial error. Methods: The multi-component superimposed EPR powder spectral simulation software was developed to simulate EPR spectrum models of the background signal (BS) and the radiation- induced signal (RS) of irradiated enamel respectively. RS was extracted from the multi-component superimposed spectrum of irradiated enamel and its amplitude was calculated. The dose-response curve was then established for calculating the doses of a group of enamel samples. The result of estimated dose was compared with that calculated by traditional method. Results: BS was simulated as a powder spectrum of gaussian line shape with the following spectrum parameters: g=2.00 35 and Hpp=0.65-1.1 mT, RS signal was also simulated as a powder spectrum but with axi-symmetric spectrum characteristics. The spectrum parameters of RS were: g ⊥ =2.0018, g ‖ =1.9965, Hpp=0.335-0.4 mT. The amplitude of RS had a linear response to radiation dose with the regression equation as y=240.74x + 76 724 (R 2 =0.9947). The expectation of relative error of dose estimation was 0.13. Conclusions: EPR simulation method has improved somehow the accuracy and reliability of enamel EPR dose estimation. (authors)

  11. ASCAT soil moisture data assimilation through the Ensemble Kalman Filter for improving streamflow simulation in Mediterranean catchments

    Science.gov (United States)

    Loizu, Javier; Massari, Christian; Álvarez-Mozos, Jesús; Casalí, Javier; Goñi, Mikel

    2016-04-01

    Assimilation of Surface Soil Moisture (SSM) observations obtained from remote sensing techniques have been shown to improve streamflow prediction at different time scales of hydrological modeling. Different sensors and methods have been tested for their application in SSM estimation, especially in the microwave region of the electromagnetic spectrum. The available observation devices include passive microwave sensors such as the Advanced Microwave Scanning Radiometer - Earth Observation System (AMSR-E) onboard the Aqua satellite and the Soil Moisture and Ocean Salinity (SMOS) mission. On the other hand, active microwave systems include Scatterometers (SCAT) onboard the European Remote Sensing satellites (ERS-1/2) and the Advanced Scatterometer (ASCAT) onboard MetOp-A satellite. Data assimilation (DA) include different techniques that have been applied in hydrology and other fields for decades. These techniques include, among others, Kalman Filtering (KF), Variational Assimilation or Particle Filtering. From the initial KF method, different techniques were developed to suit its application to different systems. The Ensemble Kalman Filter (EnKF), extensively applied in hydrological modeling improvement, shows its capability to deal with nonlinear model dynamics without linearizing model equations, as its main advantage. The objective of this study was to investigate whether data assimilation of SSM ASCAT observations, through the EnKF method, could improve streamflow simulation of mediterranean catchments with TOPLATS hydrological complex model. The DA technique was programmed in FORTRAN, and applied to hourly simulations of TOPLATS catchment model. TOPLATS (TOPMODEL-based Land-Atmosphere Transfer Scheme) was applied on its lumped version for two mediterranean catchments of similar size, located in northern Spain (Arga, 741 km2) and central Italy (Nestore, 720 km2). The model performs a separated computation of energy and water balances. In those balances, the soil

  12. Implementing effective simulation-based education to improve ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Implementing effective simulation-based education to improve maternal ... by IDRC, including the contributions IDRC is making towards Canada's maternal child ... OECD's Development Co-Operation Report highlights critical role of data to ...

  13. Improvement of the supply chain for the sugar cane exportation process employing discrete events simulation techniques - doi: 10.4025/actascitechnol.v35i4.17468

    Directory of Open Access Journals (Sweden)

    Maria Alejandra Guerrero Hernandez

    2013-10-01

    Full Text Available Current paper proposes a reduction on all logistic costs involved in the sugar cane exportation process for an important medium-size cargo harbor in South America. The strategy consisted in studying and improving the efficiency of the logistics transportation flow of merchandise between the sugar cane mills and the cargo ports by employing discrete events simulation as a methodology and the ProModel software as a simulation platform. The simulated scenarios show 89% reductions in additional costs for inventory management; 50% of the resources used for loading the containers; and an 11.4% increment in the efficiency of operations. In addition, the new planning strategy was also evaluated with either a positive or negative variation of the demand. It should be underscored that the improved scenarios (out of those simulated do not involve investments in facilities or in machinery purchasing.  

  14. Simulation error propagation for a dynamic rod worth measurement technique

    International Nuclear Information System (INIS)

    Kastanya, D.F.; Turinsky, P.J.

    1996-01-01

    KRSKO nuclear station, subsequently adapted by Westinghouse, introduced the dynamic rod worth measurement (DRWM) technique for measuring pressurized water reactor rod worths. This technique has the potential for reduced test time and primary loop waste water versus alternatives. The measurement is performed starting from a slightly supercritical state with all rods out (ARO), driving a bank in at the maximum stepping rate, and recording the ex-core detectors responses and bank position as a function of time. The static bank worth is obtained by (1) using the ex-core detectors' responses to obtain the core average flux (2) using the core average flux in the inverse point-kinetics equations to obtain the dynamic bank worth (3) converting the dynamic bank worth to the static bank worth. In this data interpretation process, various calculated quantities obtained from a core simulator are utilized. This paper presents an analysis of the sensitivity to the impact of core simulator errors on the deduced static bank worth

  15. Visualization techniques in plasma numerical simulations

    International Nuclear Information System (INIS)

    Kulhanek, P.; Smetana, M.

    2004-01-01

    Numerical simulations of plasma processes usually yield a huge amount of raw numerical data. Information about electric and magnetic fields and particle positions and velocities can be typically obtained. There are two major ways of elaborating these data. First of them is called plasma diagnostics. We can calculate average values, variances, correlations of variables, etc. These results may be directly comparable with experiments and serve as the typical quantitative output of plasma simulations. The second possibility is the plasma visualization. The results are qualitative only, but serve as vivid display of phenomena in the plasma followed-up. An experience with visualizing electric and magnetic fields via Line Integral Convolution method is described in the first part of the paper. The LIC method serves for visualization of vector fields in two dimensional section of the three dimensional plasma. The field values can be known only in grid points of three-dimensional grid. The second part of the paper is devoted to the visualization techniques of the charged particle motion. The colour tint can be used for particle temperature representation. The motion can be visualized by a trace fading away with the distance from the particle. In this manner the impressive animations of the particle motion can be achieved. (author)

  16. Improved Multiscale Entropy Technique with Nearest-Neighbor Moving-Average Kernel for Nonlinear and Nonstationary Short-Time Biomedical Signal Analysis

    Directory of Open Access Journals (Sweden)

    S. P. Arunachalam

    2018-01-01

    Full Text Available Analysis of biomedical signals can yield invaluable information for prognosis, diagnosis, therapy evaluation, risk assessment, and disease prevention which is often recorded as short time series data that challenges existing complexity classification algorithms such as Shannon entropy (SE and other techniques. The purpose of this study was to improve previously developed multiscale entropy (MSE technique by incorporating nearest-neighbor moving-average kernel, which can be used for analysis of nonlinear and non-stationary short time series physiological data. The approach was tested for robustness with respect to noise analysis using simulated sinusoidal and ECG waveforms. Feasibility of MSE to discriminate between normal sinus rhythm (NSR and atrial fibrillation (AF was tested on a single-lead ECG. In addition, the MSE algorithm was applied to identify pivot points of rotors that were induced in ex vivo isolated rabbit hearts. The improved MSE technique robustly estimated the complexity of the signal compared to that of SE with various noises, discriminated NSR and AF on single-lead ECG, and precisely identified the pivot points of ex vivo rotors by providing better contrast between the rotor core and the peripheral region. The improved MSE technique can provide efficient complexity analysis of variety of nonlinear and nonstationary short-time biomedical signals.

  17. Virtual X-ray imaging techniques in an immersive casting simulation environment

    International Nuclear Information System (INIS)

    Li, Ning; Kim, Sung-Hee; Suh, Ji-Hyun; Cho, Sang-Hyun; Choi, Jung-Gil; Kim, Myoung-Hee

    2007-01-01

    A computer code was developed to simulate radiograph of complex casting products in a CAVE TM -like environment. The simulation is based on the deterministic algorithms and ray tracing techniques. The aim of this study is to examine CAD/CAE/CAM models at the design stage, to optimize the design and inspect predicted defective regions with fast speed, good accuracy and small numerical expense. The present work discusses the algorithms for the radiography simulation of CAD/CAM model and proposes algorithmic solutions adapted from ray-box intersection algorithm and octree data structure specifically for radiographic simulation of CAE model. The stereoscopic visualization of full-size of product in the immersive casting simulation environment as well as the virtual X-ray images of castings provides an effective tool for design and evaluation of foundry processes by engineers and metallurgists

  18. Improved streaming analysis technique: spherical harmonics expansion of albedo data

    International Nuclear Information System (INIS)

    Albert, T.E.; Simmons, G.L.

    1979-01-01

    An improved albedo scattering technique was implemented with a three-dimensional Monte Carlo transport code for use in analyzing radiation streaming problems. The improvement was based on a shifted spherical Harmonics expansion of the doubly differential albedo data base. The result of the improvement was a factor of 3 to 10 reduction in data storage requirements and approximately a factor of 3 to 6 increase in computational speed. Comparisons of results obtained using the technique with measurements are shown for neutron streaming in one- and two-legged square concrete ducts

  19. Development of a Car Racing Simulator Game Using Artificial Intelligence Techniques

    Directory of Open Access Journals (Sweden)

    Marvin T. Chan

    2015-01-01

    Full Text Available This paper presents a car racing simulator game called Racer, in which the human player races a car against three game-controlled cars in a three-dimensional environment. The objective of the game is not to defeat the human player, but to provide the player with a challenging and enjoyable experience. To ensure that this objective can be accomplished, the game incorporates artificial intelligence (AI techniques, which enable the cars to be controlled in a manner that mimics natural driving. The paper provides a brief history of AI techniques in games, presents the use of AI techniques in contemporary video games, and discusses the AI techniques that were implemented in the development of Racer. A comparison of the AI techniques implemented in the Unity platform with traditional AI search techniques is also included in the discussion.

  20. Switchboard simulation to improve productivity and customer service.

    Science.gov (United States)

    LaCourse, E D

    1996-01-01

    An application of classical industrial engineering/operations research techniques (i.e., multichannel queueing analysis) and detailed workload distribution data. An analytic simulation model developed on a personal computer (PC) is used with interactive analysis to develop switchboard coverage requirements and optimal staffing schedules by time of day and day of week. This represents a tangible example of how classical techniques can be used with newer approaches and a close working relationship between the analyst and line management, to solve a practical problem of optimizing both productivity and customer service quality.

  1. Advancing botnet modeling techniques for military and security simulations

    Science.gov (United States)

    Banks, Sheila B.; Stytz, Martin R.

    2011-06-01

    Simulation environments serve many purposes, but they are only as good as their content. One of the most challenging and pressing areas that call for improved content is the simulation of bot armies (botnets) and their effects upon networks and computer systems. Botnets are a new type of malware, a type that is more powerful and potentially dangerous than any other type of malware. A botnet's power derives from several capabilities including the following: 1) the botnet's capability to be controlled and directed throughout all phases of its activity, 2) a command and control structure that grows increasingly sophisticated, and 3) the ability of a bot's software to be updated at any time by the owner of the bot (a person commonly called a bot master or bot herder.) Not only is a bot army powerful and agile in its technical capabilities, a bot army can be extremely large, can be comprised of tens of thousands, if not millions, of compromised computers or it can be as small as a few thousand targeted systems. In all botnets, their members can surreptitiously communicate with each other and their command and control centers. In sum, these capabilities allow a bot army to execute attacks that are technically sophisticated, difficult to trace, tactically agile, massive, and coordinated. To improve our understanding of their operation and potential, we believe that it is necessary to develop computer security simulations that accurately portray bot army activities, with the goal of including bot army simulations within military simulation environments. In this paper, we investigate issues that arise when simulating bot armies and propose a combination of the biologically inspired MSEIR infection spread model coupled with the jump-diffusion infection spread model to portray botnet propagation.

  2. Managing health care decisions and improvement through simulation modeling.

    Science.gov (United States)

    Forsberg, Helena Hvitfeldt; Aronsson, Håkan; Keller, Christina; Lindblad, Staffan

    2011-01-01

    Simulation modeling is a way to test changes in a computerized environment to give ideas for improvements before implementation. This article reviews research literature on simulation modeling as support for health care decision making. The aim is to investigate the experience and potential value of such decision support and quality of articles retrieved. A literature search was conducted, and the selection criteria yielded 59 articles derived from diverse applications and methods. Most met the stated research-quality criteria. This review identified how simulation can facilitate decision making and that it may induce learning. Furthermore, simulation offers immediate feedback about proposed changes, allows analysis of scenarios, and promotes communication on building a shared system view and understanding of how a complex system works. However, only 14 of the 59 articles reported on implementation experiences, including how decision making was supported. On the basis of these articles, we proposed steps essential for the success of simulation projects, not just in the computer, but also in clinical reality. We also presented a novel concept combining simulation modeling with the established plan-do-study-act cycle for improvement. Future scientific inquiries concerning implementation, impact, and the value for health care management are needed to realize the full potential of simulation modeling.

  3. An improved methodology for dynamic modelling and simulation of ...

    Indian Academy of Sciences (India)

    The diversity of the processes and the complexity of the drive system .... modelling the specific event, general simulation tools such as Matlab R provide the user with tools for creating ..... using the pulse width modulation (PWM) techniques.

  4. Improving SWAT for simulating water and carbon fluxes of forest ecosystems

    International Nuclear Information System (INIS)

    Yang, Qichun; Zhang, Xuesong

    2016-01-01

    As a widely used watershed model for assessing impacts of anthropogenic and natural disturbances on water quantity and quality, the Soil and Water Assessment Tool (SWAT) has not been extensively tested in simulating water and carbon fluxes of forest ecosystems. Here, we examine SWAT simulations of evapotranspiration (ET), net primary productivity (NPP), net ecosystem exchange (NEE), and plant biomass at ten AmeriFlux forest sites across the U.S. We identify unrealistic radiation use efficiency (Bio-E), large leaf to biomass fraction (Bio-LEAF), and missing phosphorus supply from parent material weathering as the primary causes for the inadequate performance of the default SWAT model in simulating forest dynamics. By further revising the relevant parameters and processes, SWAT's performance is substantially improved. Based on the comparison between the improved SWAT simulations and flux tower observations, we discuss future research directions for further enhancing model parameterization and representation of water and carbon cycling for forests. - Graphical abstract: Evaluating and improving SWAT simulations of water and carbon cycling over ten AmeriFlux sites across the United States. - Highlights: • The default forest parameterization in SWAT results in inadequate simulations of water and carbon. • Radiation use efficiency, leaf to biomass fraction, and parent material weathering processes are modified. • Revised SWAT provides improved simulations of evapotranspiration and net ecosystem exchange

  5. Improving SWAT for simulating water and carbon fluxes of forest ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qichun [Joint Global Change Research Institute, Pacific Northwest National Lab, College Park, MD 20740 (United States); Zhang, Xuesong, E-mail: xuesong.zhang@pnnl.gov [Joint Global Change Research Institute, Pacific Northwest National Lab, College Park, MD 20740 (United States); Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824 (United States)

    2016-11-01

    As a widely used watershed model for assessing impacts of anthropogenic and natural disturbances on water quantity and quality, the Soil and Water Assessment Tool (SWAT) has not been extensively tested in simulating water and carbon fluxes of forest ecosystems. Here, we examine SWAT simulations of evapotranspiration (ET), net primary productivity (NPP), net ecosystem exchange (NEE), and plant biomass at ten AmeriFlux forest sites across the U.S. We identify unrealistic radiation use efficiency (Bio-E), large leaf to biomass fraction (Bio-LEAF), and missing phosphorus supply from parent material weathering as the primary causes for the inadequate performance of the default SWAT model in simulating forest dynamics. By further revising the relevant parameters and processes, SWAT's performance is substantially improved. Based on the comparison between the improved SWAT simulations and flux tower observations, we discuss future research directions for further enhancing model parameterization and representation of water and carbon cycling for forests. - Graphical abstract: Evaluating and improving SWAT simulations of water and carbon cycling over ten AmeriFlux sites across the United States. - Highlights: • The default forest parameterization in SWAT results in inadequate simulations of water and carbon. • Radiation use efficiency, leaf to biomass fraction, and parent material weathering processes are modified. • Revised SWAT provides improved simulations of evapotranspiration and net ecosystem exchange.

  6. Modeling and Simulation of Voids in Composite Tape Winding Process Based on Domain Superposition Technique

    Science.gov (United States)

    Deng, Bo; Shi, Yaoyao

    2017-11-01

    The tape winding technology is an effective way to fabricate rotationally composite materials. Nevertheless, some inevitable defects will seriously influence the performance of winding products. One of the crucial ways to identify the quality of fiber-reinforced composite material products is examining its void content. Significant improvement in products' mechanical properties can be achieved by minimizing the void defect. Two methods were applied in this study, finite element analysis and experimental testing, respectively, to investigate the mechanism of how void forming in composite tape winding processing. Based on the theories of interlayer intimate contact and Domain Superposition Technique (DST), a three-dimensional model of prepreg tape void with SolidWorks has been modeled in this paper. Whereafter, ABAQUS simulation software was used to simulate the void content change with pressure and temperature. Finally, a series of experiments were performed to determine the accuracy of the model-based predictions. The results showed that the model is effective for predicting the void content in the composite tape winding process.

  7. MATLAB Simulation of UPQC for Power Quality Mitigation Using an Ant Colony Based Fuzzy Control Technique.

    Science.gov (United States)

    Kumarasabapathy, N; Manoharan, P S

    2015-01-01

    This paper proposes a fuzzy logic based new control scheme for the Unified Power Quality Conditioner (UPQC) for minimizing the voltage sag and total harmonic distortion in the distribution system consequently to improve the power quality. UPQC is a recent power electronic module which guarantees better power quality mitigation as it has both series-active and shunt-active power filters (APFs). The fuzzy logic controller has recently attracted a great deal of attention and possesses conceptually the quality of the simplicity by tackling complex systems with vagueness and ambiguity. In this research, the fuzzy logic controller is utilized for the generation of reference signal controlling the UPQC. To enable this, a systematic approach for creating the fuzzy membership functions is carried out by using an ant colony optimization technique for optimal fuzzy logic control. An exhaustive simulation study using the MATLAB/Simulink is carried out to investigate and demonstrate the performance of the proposed fuzzy logic controller and the simulation results are compared with the PI controller in terms of its performance in improving the power quality by minimizing the voltage sag and total harmonic distortion.

  8. MATLAB Simulation of UPQC for Power Quality Mitigation Using an Ant Colony Based Fuzzy Control Technique

    Directory of Open Access Journals (Sweden)

    N. Kumarasabapathy

    2015-01-01

    Full Text Available This paper proposes a fuzzy logic based new control scheme for the Unified Power Quality Conditioner (UPQC for minimizing the voltage sag and total harmonic distortion in the distribution system consequently to improve the power quality. UPQC is a recent power electronic module which guarantees better power quality mitigation as it has both series-active and shunt-active power filters (APFs. The fuzzy logic controller has recently attracted a great deal of attention and possesses conceptually the quality of the simplicity by tackling complex systems with vagueness and ambiguity. In this research, the fuzzy logic controller is utilized for the generation of reference signal controlling the UPQC. To enable this, a systematic approach for creating the fuzzy membership functions is carried out by using an ant colony optimization technique for optimal fuzzy logic control. An exhaustive simulation study using the MATLAB/Simulink is carried out to investigate and demonstrate the performance of the proposed fuzzy logic controller and the simulation results are compared with the PI controller in terms of its performance in improving the power quality by minimizing the voltage sag and total harmonic distortion.

  9. The Crucible simulation: Behavioral simulation improves clinical leadership skills and understanding of complex health policy change.

    Science.gov (United States)

    Cohen, Daniel; Vlaev, Ivo; McMahon, Laurie; Harvey, Sarah; Mitchell, Andy; Borovoi, Leah; Darzi, Ara

    2017-05-11

    The Health and Social Care Act 2012 represents the most complex National Health Service reforms in history. High-quality clinical leadership is important for successful implementation of health service reform. However, little is known about the effectiveness of current leadership training. This study describes the use of a behavioral simulation to improve the knowledge and leadership of a cohort of medical doctors expected to take leadership roles in the National Health Service. A day-long behavioral simulation (The Crucible) was developed and run based on a fictitious but realistic health economy. Participants completed pre- and postsimulation questionnaires generating qualitative and quantitative data. Leadership skills, knowledge, and behavior change processes described by the "theory of planned behavior" were self-assessed pre- and postsimulation. Sixty-nine medical doctors attended. Participants deemed the simulation immersive and relevant. Significant improvements were shown in perceived knowledge, capability, attitudes, subjective norms, intentions, and leadership competency following the program. Nearly one third of participants reported that they had implemented knowledge and skills from the simulation into practice within 4 weeks. This study systematically demonstrates the effectiveness of behavioral simulation for clinical management training and understanding of health policy reform. Potential future uses and strategies for analysis are discussed. High-quality care requires understanding of health systems and strong leadership. Policymakers should consider the use of behavioral simulation to improve understanding of health service reform and development of leadership skills in clinicians, who readily adopt skills from simulation into everyday practice.

  10. Application of simulation techniques in the probabilistic fracture mechanics

    International Nuclear Information System (INIS)

    De Ruyter van Steveninck, J.L.

    1995-03-01

    The Monte Carlo simulation is applied on a model of the fracture mechanics in order to assess the applicability of this simulation technique in the probabilistic fracture mechanics. By means of the fracture mechanics model the brittle fracture of a steel container or pipe with defects can be predicted. By means of the Monte Carlo simulation also the uncertainty regarding failures can be determined. Based on the variations in the toughness of the fracture and the defect dimensions the distribution of the chance of failure is determined. Also attention is paid to the impact of dependency between uncertain variables. Furthermore, the influence of the applied distributions of the uncertain variables and non-destructive survey on the chance of failure is analyzed. The Monte Carlo simulation results agree quite well with the results of other methods from the probabilistic fracture mechanics. If an analytic expression can be found for the chance of failure, it is possible to determine the variation of the chance of failure, next to an estimation of the chance of failure. It also appears that the dependency between the uncertain variables has a large impact on the chance of failure. It is also concluded from the simulation that the chance of failure strongly depends on the crack depth, and therefore of the distribution of the crack depth. 15 figs., 7 tabs., 12 refs

  11. Cognitive environment simulation: An artificial intelligence system for human performance assessment: Cognitive reliability analysis technique: [Technical report, May 1986-June 1987

    International Nuclear Information System (INIS)

    Woods, D.D.; Roth, E.M.

    1987-11-01

    This report documents the results of Phase II of a three phase research program to develop and validate improved methods to model the cognitive behavior of nuclear power plant (NPP) personnel. In Phase II a dynamic simulation capability for modeling how people form intentions to act in NPP emergency situations was developed based on techniques from artificial intelligence. This modeling tool, Cognitive Environment Simulation or CES, simulates the cognitive processes that determine situation assessment and intention formation. It can be used to investigate analytically what situations and factors lead to intention failures, what actions follow from intention failures (e.g., errors of omission, errors of commission, common mode errors), the ability to recover from errors or additional machine failures, and the effects of changes in the NPP person-machine system. The Cognitive Reliability Assessment Technique (or CREATE) was also developed in Phase II to specify how CES can be used to enhance the measurement of the human contribution to risk in probabilistic risk assessment (PRA) studies. 34 refs., 7 figs., 1 tab

  12. Upgrading the Fast Calorimeter Simulation in ATLAS

    CERN Document Server

    Schaarschmidt, Jana; The ATLAS collaboration

    2017-01-01

    The tremendous need for simulated samples now and even more so in the future, encourage the development of fast simulation techniques. The Fast Calorimeter Simulation is a faster though less accurate alternative to the full calorimeter simulation with Geant4. It is based on parametrizing the longitudunal and lateral energy deposits of single particles in the ATLAS calorimeter. Principal component analysis and machine learning techniques are used to improve the performance and decrease the memory need compared to the current version of the ATLAS Fast Calorimeter Simulation. The parametrizations are expanded to cover very high energies and very forward detector regions, to increase the applicability of the tool. A prototype of this upgraded Fast Calorimeter Simulation has been developed and first validations with single particles show substantial improvements over the previous version.

  13. Understanding molecular simulation from algorithms to applications

    CERN Document Server

    Frenkel, Daan

    2001-01-01

    Understanding Molecular Simulation: From Algorithms to Applications explains the physics behind the ""recipes"" of molecular simulation for materials science. Computer simulators are continuously confronted with questions concerning the choice of a particular technique for a given application. A wide variety of tools exist, so the choice of technique requires a good understanding of the basic principles. More importantly, such understanding may greatly improve the efficiency of a simulation program. The implementation of simulation methods is illustrated in pseudocodes and their practic

  14. Improved non-LTE simulation algorithm

    Science.gov (United States)

    Busquet, Michel; Klapisch, Marcel; Colombant, Denis; Fyfe, David; Gardner, John

    2008-11-01

    The RAdiation Dependent Ionization Model (RADIOM)- a.k.a Busquet's model-[1] has proven its success in simulating non --LTE effects in laser fusion plasmas [2]. This improved algorithm can take into account Auger effect by a new parameter fitted to SCROLL [3] results. It is independent of the photon binning thanks to a projection on a standard grid. It guarantees smoother convergence to LTE. This algorithm has been implemented in a new way in the hydro-code FASTnD. Hydro simulations on the recent subMJ targets[4], with and without non-LTE corrections will be shown. [1] M. Busquet, Phys. Fluids B 5, 4191(1993). [2] D.G. Colombant et al, Phys. Plas. 7,2046 (2000). [3] A. Bar-Shalom, J. Oreg M. Klapisch, J. Quant. Spectr. Rad. Transf. 65 ,43 (2000). [4] S. P. Obenschain, D. G. Colombant, A. J. Schmitt et al., Phys. Plasmas 13, 056320 (2006).

  15. Radiotracer technique for leakage detection under simulated conditions

    International Nuclear Information System (INIS)

    Yelgaonkar, V.N.; Sharma, V.K.; Tapase, A.S.

    2001-01-01

    Radiotracer techniques are often used to locate leaks in underground pipelines. An attempt was made to standardize radiotracer pulse migration in terms of minimum detectable limit. For this purpose a 6 inch diameter 1200 long steel pipe was used. Two leak rates viz. 10 litres per minute and 1 litre per minute with an accuracy of ± 10% were simulated. The experiments on this pipeline showed that this method could be used to locate a leak of the order of 1 litre per minute in a 6 inch diameter isolated underground pipeline. (author)

  16. Crack growth simulation for plural crack using hexahedral mesh generation technique

    International Nuclear Information System (INIS)

    Orita, Y; Wada, Y; Kikuchi, M

    2010-01-01

    This paper describes a surface crack growth simulation using a new mesh generation technique. The generated mesh is constituted of all hexahedral elements. Hexahedral elements are suitable for an analysis of fracture mechanics parameters, i.e. stress intensity factor. The advantage of a hexahedral mesh is good accuracy of an analysis and less number of degrees of freedoms than a tetrahedral mesh. In this study, a plural crack growth simulation is computed using the hexahedral mesh and its distribution of stress intensity factor is investigated.

  17. Who is that masked educator? Deconstructing the teaching and learning processes of an innovative humanistic simulation technique.

    Science.gov (United States)

    McAllister, Margaret; Searl, Kerry Reid; Davis, Susan

    2013-12-01

    Simulation learning in nursing has long made use of mannequins, standardized actors and role play to allow students opportunity to practice technical body-care skills and interventions. Even though numerous strategies have been developed to mimic or amplify clinical situations, a common problem that is difficult to overcome in even the most well-executed simulation experiences, is that students may realize the setting is artificial and fail to fully engage, remember or apply the learning. Another problem is that students may learn technical competence but remain uncertain about communicating with the person. Since communication capabilities are imperative in human service work, simulation learning that only achieves technical competence in students is not fully effective for the needs of nursing education. Furthermore, while simulation learning is a burgeoning space for innovative practices, it has been criticized for the absence of a basis in theory. It is within this context that an innovative simulation learning experience named "Mask-Ed (KRS simulation)", has been deconstructed and the active learning components examined. Establishing a theoretical basis for creative teaching and learning practices provides an understanding of how, why and when simulation learning has been effective and it may help to distinguish aspects of the experience that could be improved. Three conceptual theoretical fields help explain the power of this simulation technique: Vygotskian sociocultural learning theory, applied theatre and embodiment. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Software quality and process improvement in scientific simulation codes

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosiano, J.; Webster, R. [Los Alamos National Lab., NM (United States)

    1997-11-01

    This report contains viewgraphs on the quest to develope better simulation code quality through process modeling and improvement. This study is based on the experience of the authors and interviews with ten subjects chosen from simulation code development teams at LANL. This study is descriptive rather than scientific.

  19. Improving the Ar I and II branching ratio calibration method: Monte Carlo simulations of effects from photon scattering/reflecting in hollow cathodes

    Science.gov (United States)

    Lawler, J. E.; Den Hartog, E. A.

    2018-03-01

    The Ar I and II branching ratio calibration method is discussed with the goal of improving the technique. This method of establishing a relative radiometric calibration is important in ongoing research to improve atomic transition probabilities for quantitative spectroscopy in astrophysics and other fields. Specific suggestions are presented along with Monte Carlo simulations of wavelength dependent effects from scattering/reflecting of photons in a hollow cathode.

  20. Determination of output factor for 6 MV small photon beam: comparison between Monte Carlo simulation technique and microDiamond detector

    International Nuclear Information System (INIS)

    Krongkietlearts, K; Tangboonduangjit, P; Paisangittisakul, N

    2016-01-01

    In order to improve the life's quality for a cancer patient, the radiation techniques are constantly evolving. Especially, the two modern techniques which are intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) are quite promising. They comprise of many small beam sizes (beamlets) with various intensities to achieve the intended radiation dose to the tumor and minimal dose to the nearby normal tissue. The study investigates whether the microDiamond detector (PTW manufacturer), a synthetic single crystal diamond detector, is suitable for small field output factor measurement. The results were compared with those measured by the stereotactic field detector (SFD) and the Monte Carlo simulation (EGSnrc/BEAMnrc/DOSXYZ). The calibration of Monte Carlo simulation was done using the percentage depth dose and dose profile measured by the photon field detector (PFD) of the 10×10 cm 2 field size with 100 cm SSD. Comparison of the values obtained from the calculations and measurements are consistent, no more than 1% difference. The output factors obtained from the microDiamond detector have been compared with those of SFD and Monte Carlo simulation, the results demonstrate the percentage difference of less than 2%. (paper)

  1. Numerical convergence improvements for porflow unsaturated flow simulations

    Energy Technology Data Exchange (ETDEWEB)

    Flach, Greg [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-08-14

    Section 3.6 of SRNL (2016) discusses various PORFLOW code improvements to increase modeling efficiency, in preparation for the next E-Area Performance Assessment (WSRC 2008) revision. This memorandum documents interaction with Analytic & Computational Research, Inc. (http://www.acricfd.com/default.htm) to improve numerical convergence efficiency using PORFLOW version 6.42 for unsaturated flow simulations.

  2. Simulation for nuclear reactor technology

    International Nuclear Information System (INIS)

    Walton, D.G.

    1985-01-01

    Mathematical modelling forms the cornerstone of both the physical sciences and the engineering sciences. Computer modelling represents an extension of mathematical modelling into areas which are either not sufficiently accurate or not conveniently modelled by analytical techniques and where highly complex models can be investigated on a sufficiently short timescale. Simulation represents the application of these modelling techniques to real systems, thus enabling information on plant characteristics to be gained without either constructing or operating the full-scale plant or system under consideration. Developments in computer systems modelling techniques, safety and operating philosophy, and human psychology studies lead to improvements in simulation practice. New concepts in simulation also lead to a demand for new types of computers, dedicated computer systems are increasingly being developed for plant analysis, and the advent and development of microprocessors has also led to new techniques both in simulation and simulators. Progress in these areas is presented in this book

  3. Real-time surgical simulation for deformable soft-tissue objects with a tumour using Boundary Element techniques

    Science.gov (United States)

    Wang, P.; Becker, A. A.; Jones, I. A.; Glover, A. T.; Benford, S. D.; Vloeberghs, M.

    2009-08-01

    A virtual-reality real-time simulation of surgical operations that incorporates the inclusion of a hard tumour is presented. The software is based on Boundary Element (BE) technique. A review of the BE formulation for real-time analysis of two-domain deformable objects, using the pre-solution technique, is presented. The two-domain BE software is incorporated into a surgical simulation system called VIRS to simulate the initiation of a cut on the surface of the soft tissue and extending the cut deeper until the tumour is reached.

  4. Real-time surgical simulation for deformable soft-tissue objects with a tumour using Boundary Element techniques

    International Nuclear Information System (INIS)

    Wang, P; Becker, A A; Jones, I A; Glover, A T; Benford, S D; Vloeberghs, M

    2009-01-01

    A virtual-reality real-time simulation of surgical operations that incorporates the inclusion of a hard tumour is presented. The software is based on Boundary Element (BE) technique. A review of the BE formulation for real-time analysis of two-domain deformable objects, using the pre-solution technique, is presented. The two-domain BE software is incorporated into a surgical simulation system called VIRS to simulate the initiation of a cut on the surface of the soft tissue and extending the cut deeper until the tumour is reached.

  5. A 3D technique for simulation of irregular electron treatment fields using a digital camera

    International Nuclear Information System (INIS)

    Bassalow, Roustem; Sidhu, Narinder P.

    2003-01-01

    Cerrobend inserts, which define electron field apertures, are manufactured at our institution using perspex templates. Contours are reproduced manually on these templates at the simulator from the field outlines drawn on the skin or mask of a patient. A previously reported technique for simulation of electron treatment fields uses a digital camera to eliminate the need for such templates. However, avoidance of the image distortions introduced by non-flat surfaces on which the electron field outlines were drawn could only be achieved by limiting the application of this technique to surfaces which were flat or near flat. We present a technique that employs a digital camera and allows simulation of electron treatment fields contoured on an anatomical surface of an arbitrary three-dimensional (3D) shape, such as that of the neck, extremities, face, or breast. The procedure is fast, accurate, and easy to perform

  6. Acquainting Future Office Employees with Productivity-Improvement Techniques.

    Science.gov (United States)

    Quible, Zane K.

    1982-01-01

    Examines factors affecting productivity (government regulations, energy costs, decline in the work ethic, capital investment, number of service workers, work force characteristics, management practices, and unions), and techniques to improve productivity (employee involvement, job structure, communication, flexitime, employee upgrading, incentive…

  7. Healthcare system simulation using Witness

    International Nuclear Information System (INIS)

    Khakdaman, Masoud; Zeinahvazi, Milad; Zohoori, Bahareh; Nasiri, Fardokht; Wong, Kuan Yew

    2013-01-01

    Simulation techniques have a proven track record in manufacturing industry as well as other areas such as healthcare system improvement. In this study, simulation model of a health center in Malaysia is developed through the application of WITNESS simulation software which has shown its flexibility and capability in manufacturing industry. Modelling procedure is started through process mapping and data collection and continued with model development, verification, validation and experimentation. At the end, final results and possible future improvements are demonstrated.

  8. In vitro techniques for crop improvement

    International Nuclear Information System (INIS)

    1985-01-01

    The film refers to principles of plant tissue culture - laboratory requirements, media preparation, explant establishment and subculturing method. In vitro growth and development of crop plants are demonstrate and the application of in vitro techniques in plant breeding is discussed. The second part of the film shows the application of cell, tissue and organ culture in plants. Micropropagation and virus eradication are important technologies for the improvement of vegetatively propagated plants; zygotic embryo rescue techniques are used for distant hybridization, especially in cereals. Plant biotechnology offers a potent means for the in vitro generation of enhanced genetic variability - somaclonal and mutagen induced variation. Principles of the isolation and culture of plant protoplasts are explained and their potential for somatic hybridization in higher plants is demonstrated. Haploids are valuable to accelerate breeding cycles of plants. Plant biotechnology is described as an important complementary tool to conventional plant breeding methods

  9. Report on best practice for improved μ-IM injection moulding simulation

    DEFF Research Database (Denmark)

    Tosello, Guido; Costa, Franco; Hansen, Hans Nørgaard

    2010-01-01

    Data analysis and simulations on micro-moulding experiments have been conducted. Micro moulding simulations have been executed taking into account actual processing conditions implementation in the software. Numerous aspects of the simulation set-up have been considered in order to improve the si...

  10. Gaming, simulations and society research scope and perspective

    CERN Document Server

    Shiratori, R; Kato, F

    2014-01-01

    This book presents a current research scope and perspective of Simulation and Gaming.Theoretical problems of Simulation and Gaming will be examined with a view to improving the social sciences through the introduction of the techniques and concepts of Simulation and Gaming.The fields of economics, political science, psychology and business management can all be radically improved by introducing such techniques of Simulation and Gaming as the Agent-Based Modelling.Other important topics are the analysis of philosophical foundations in Simulation and Gaming as an academic discipline.The ever growing and massive popularity of PC and arcade games cannot be ignored.Their potential as agents of education and their essentially violent nature raise many ethical and moral problems that need to be addressed.

  11. Development and validation of predictive simulation model of multi-layer repair welding process by temper bead technique

    International Nuclear Information System (INIS)

    Okano, Shigetaka; Miyasaka, Fumikazu; Mochizuki, Masahito; Tanaka, Manabu

    2015-01-01

    Stress corrosion cracking (SCC) has recently been observed in the nickel base alloy weld metal of dissimilar pipe joint used in pressurized water reactor (PWR) . Temper bead technique has been developed as one of repair procedures against SCC applicable in case that post weld heat treatment (PWHT) is difficult to carry out. In this regard, however it is essential to pass the property and performance qualification test to confirm the effect of tempering on the mechanical properties at repair welds before temper bead technique is actually used in practice. Thus the appropriate welding procedure conditions in temper bead technique are determined on the basis of the property and performance qualification testing. It is necessary for certifying the structural soundness and reliability at repair welds but takes a lot of work and time in the present circumstances. Therefore it is desirable to establish the reasonable alternatives for qualifying the property and performance at repair welds. In this study, mathematical modeling and numerical simulation procedures were developed for predicting weld bead configuration and temperature distribution during multi-layer repair welding process by temper bead technique. In the developed simulation technique, characteristics of heat source in temper bead welding are calculated from weld heat input conditions through the arc plasma simulation and then weld bead configuration and temperature distribution during temper bead welding are calculated from characteristics of heat source obtained through the coupling analysis between bead surface shape and thermal conduction. The simulation results were compared with the experimental results under the same welding heat input conditions. As the results, the bead surface shape and temperature distribution, such as A cl lines, were in good agreement between simulation and experimental results. It was concluded that the developed simulation technique has the potential to become useful for

  12. Quality comparison between DEF-10 digital image from simulation technique and Computed Tomography (CR) technique in industrial radiography

    International Nuclear Information System (INIS)

    Siti Nur Syatirah Ismail

    2012-01-01

    The study was conducted to make comparison of digital image quality of DEF-10 from the techniques of simulation and computed radiography (CR). The sample used is steel DEF-10 with thickness of 15.28 mm. In this study, the sample is exposed to radiation from X-ray machine (ISOVOLT Titan E) with certain parameters. The parameters used in this study such as current, volt, exposure time and distance are specified. The current and distance of 3 mA and 700 mm respectively are specified while the applied voltage varies at 140, 160, 180 and 200 kV. The exposure time is reduced at a rate of 0, 20, 40, 60 and 80 % for each sample exposure. Digital image of simulation produced from aRTist software whereas digital image of computed radiography produced from imaging plate. Therefore, both images were compared qualitatively (sensitivity) and quantitatively (Signal to-Noise Ratio; SNR, Basic Spatial Resolution; SRb and LOP size) using Isee software. Radiographic sensitivity is indicated by Image Quality Indicator (IQI) which is the ability of the CR system and aRTist software to identify IQI of wire type when the time exposure is reduced up to 80% according to exposure chart ( D7; ISOVOLT Titan E). The image of the thinnest wire diameter achieved by radiograph from simulation and CR are the wire numbered 7 rather than the wire numbered 8 required by the standard. In quantitative comparison, this study shows that the SNR values decreases with reducing exposure time. SRb values increases for simulation and decreases for CR when the exposure time decreases and the good image quality can be achieved at 80% reduced exposure time. The high SNR and SRb values produced good image quality in CR and simulation techniques respectively. (author)

  13. GATE: Improving the computational efficiency

    International Nuclear Information System (INIS)

    Staelens, S.; De Beenhouwer, J.; Kruecker, D.; Maigne, L.; Rannou, F.; Ferrer, L.; D'Asseler, Y.; Buvat, I.; Lemahieu, I.

    2006-01-01

    GATE is a software dedicated to Monte Carlo simulations in Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET). An important disadvantage of those simulations is the fundamental burden of computation time. This manuscript describes three different techniques in order to improve the efficiency of those simulations. Firstly, the implementation of variance reduction techniques (VRTs), more specifically the incorporation of geometrical importance sampling, is discussed. After this, the newly designed cluster version of the GATE software is described. The experiments have shown that GATE simulations scale very well on a cluster of homogeneous computers. Finally, an elaboration on the deployment of GATE on the Enabling Grids for E-Science in Europe (EGEE) grid will conclude the description of efficiency enhancement efforts. The three aforementioned methods improve the efficiency of GATE to a large extent and make realistic patient-specific overnight Monte Carlo simulations achievable

  14. A practical 3D printed simulator for endoscopic endonasal transsphenoidal surgery to improve basic operational skills.

    Science.gov (United States)

    Wen, Guodao; Cong, ZiXiang; Liu, KaiDong; Tang, Chao; Zhong, Chunyu; Li, Liwen; Dai, XuJie; Ma, Chiyuan

    2016-06-01

    We aimed to present a practical three-dimensional (3D) printed simulator to comprehensively and effectively accelerate the learning curve of endoscopic endonasal transsphenoidal surgery (EETS). The 3D printed simulator consists of three parts: (1) skull frame, (2) the nasal passage and the nasal alar of the face, and (3) a modified sella turcica. We aimed to improve three basic operational skills of surgeons: drilling, curetting, and aspirating. Eighteen neurosurgeons and five post-graduates were recruited and consented for the training. For trainees, (1) as the training progressed, the scores increased gradually, (2) a significant increase in the average scores was observed in the tenth training compared to the first training, and (3) there is a significant decrease in trainee variability in the shortening of the gap. The 18 neurosurgeons were divided into three groups: experts, assistants, and observers. For all three basic operations, (1) the average score of experts was obviously higher than that of the assistants, observers, and trainees' tenth training and (2) the average scores of assistants and observers were obviously higher than that of trainees' first training. A significant high in the average score between the assistants and the observers was seen for aspirating, but not for drilling or curetting. For curetting and aspirating, the tenth training average score of trainees was obviously higher than that of assistants and observers. This 3D printed simulator allows different endoscopic basic operations to be simulated and improves the EETS techniques of surgeons. We believed it to be a practical, simple, and low-cost simulator.

  15. Improving the precision and accuracy of Mont Carlo simulation in positron emission tomography

    International Nuclear Information System (INIS)

    Picard, Y.; Thompson, C.J.; Marrett, S.

    1992-01-01

    This paper reports that most of the gamma-rays generated following positron annihilation in subjects undergoing PET studied never reach the detectors of a positron imaging device. Similarly, simulations of PET systems waste considerable time generating events which will never be detected. Simulation efficiency (in terms of detected photon pairs per CPU second) can be improved by generating only rays whose angular distribution gives them a reasonable chance of ultimate detection. For many events in which the original rays are directed generally towards the detectors, the precision of the final simulation can be improved by recycling them without reseeding the random number generator, giving them a second or greater chance of being detected. For simulation programs which cascade the simulation process into source, collimator, and detection phases, recycling can improve the precision of the simulation without requiring larger files of events from the source distribution simulation phase

  16. USE OF ARTIFICIAL INTELLIGENCE TECHNIQUES IN QUALITY IMPROVING PROCESS

    OpenAIRE

    KALİTE İYİLEŞTİRME SÜRECİNDE YAPAY ZEKÃ KAYA; Orhan ENGİN

    2005-01-01

    Today, changing of competition conditions and customer preferences caused to happen many differences in the viewpoint of firms' quality studies. At the same time, improvements in computer technologies accelerated use of artificial intelligence. Artificial intelligence technologies are being used to solve many industry problems. In this paper, we investigated the use of artificial intelligence techniques to solve quality problems. The artificial intelligence techniques, which are used in quali...

  17. Experiment and Simulation of Medium-Duty Tactical Truck for Fuel Economy Improvement

    Directory of Open Access Journals (Sweden)

    Allen M. Quail

    2011-02-01

    Full Text Available Fuel economy improvement on medium-duty tactical truck has and continues to be a significant initiative for the U.S. Army. The focus of this study is the investigation of Automated Manual Transmissions (AMT and mild hybridization powertrain that have potential to improve the fuel economy of the 2.5-ton cargo trucks. The current platform uses a seven-speed automatic transmission. This study utilized a combination of on-road experimental vehicle data and analytical vehicle modeling and simulation. This paper presents the results of (1 establishment of a validated, high fidelity baseline analytical vehicle model, (2 modeling and simulation of two AMTs and their control strategy, (3 optimization of transmissions shift schedules, and (4 modeling and simulation of engine idle stop/start and Belt-Integrated-Starter-Generator (B-ISG systems to improve the fuel economy. The fuel economy discrepancy between experimental average and the baseline simulation result was 2.87%. The simulation results indicated a 14.5% and 12.2% fuel economy improvement for the 10-speed and 12-speed AMT respectively. A stop/start system followed by a B-ISG mild hybrid system incorporating regenerative braking was estimated to improve fuel economy 3.39% and 10.2% respectively.

  18. A Monte Carlo simulation study of an improved K-edge log-subtraction X-ray imaging using a photon counting CdTe detector

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Youngjin, E-mail: radioyoungj@gmail.com [Department of Radiological Science, Eulji University, 553, Sanseong-daero, Sujeong-gu, Seongnam-si, Gyeonggi-do (Korea, Republic of); Lee, Amy Candy [Department of Mathematics and Statistics, McGill University (Canada); Kim, Hee-Joung [Department of Radiological Science and Radiation Convergence Engineering, Yonsei University (Korea, Republic of)

    2016-09-11

    Recently, significant effort has been spent on the development of photons counting detector (PCD) based on a CdTe for applications in X-ray imaging system. The motivation of developing PCDs is higher image quality. Especially, the K-edge subtraction (KES) imaging technique using a PCD is able to improve image quality and useful for increasing the contrast resolution of a target material by utilizing contrast agent. Based on above-mentioned technique, we presented an idea for an improved K-edge log-subtraction (KELS) imaging technique. The KELS imaging technique based on the PCDs can be realized by using different subtraction energy width of the energy window. In this study, the effects of the KELS imaging technique and subtraction energy width of the energy window was investigated with respect to the contrast, standard deviation, and CNR with a Monte Carlo simulation. We simulated the PCD X-ray imaging system based on a CdTe and polymethylmethacrylate (PMMA) phantom which consists of the various iodine contrast agents. To acquired KELS images, images of the phantom using above and below the iodine contrast agent K-edge absorption energy (33.2 keV) have been acquired at different energy range. According to the results, the contrast and standard deviation were decreased, when subtraction energy width of the energy window is increased. Also, the CNR using a KELS imaging technique is higher than that of the images acquired by using whole energy range. Especially, the maximum differences of CNR between whole energy range and KELS images using a 1, 2, and 3 mm diameter iodine contrast agent were acquired 11.33, 8.73, and 8.29 times, respectively. Additionally, the optimum subtraction energy width of the energy window can be acquired at 5, 4, and 3 keV for the 1, 2, and 3 mm diameter iodine contrast agent, respectively. In conclusion, we successfully established an improved KELS imaging technique and optimized subtraction energy width of the energy window, and based on

  19. Quality Improvement With Discrete Event Simulation: A Primer for Radiologists.

    Science.gov (United States)

    Booker, Michael T; O'Connell, Ryan J; Desai, Bhushan; Duddalwar, Vinay A

    2016-04-01

    The application of simulation software in health care has transformed quality and process improvement. Specifically, software based on discrete-event simulation (DES) has shown the ability to improve radiology workflows and systems. Nevertheless, despite the successful application of DES in the medical literature, the power and value of simulation remains underutilized. For this reason, the basics of DES modeling are introduced, with specific attention to medical imaging. In an effort to provide readers with the tools necessary to begin their own DES analyses, the practical steps of choosing a software package and building a basic radiology model are discussed. In addition, three radiology system examples are presented, with accompanying DES models that assist in analysis and decision making. Through these simulations, we provide readers with an understanding of the theory, requirements, and benefits of implementing DES in their own radiology practices. Copyright © 2016 American College of Radiology. All rights reserved.

  20. New Teaching Techniques to Improve Critical Thinking. The Diaprove Methodology

    Science.gov (United States)

    Saiz, Carlos; Rivas, Silvia F.

    2016-01-01

    The objective of this research is to ascertain whether new instructional techniques can improve critical thinking. To achieve this goal, two different instruction techniques (ARDESOS--group 1--and DIAPROVE--group 2--) were studied and a pre-post assessment of critical thinking in various dimensions such as argumentation, inductive reasoning,…

  1. Emergency in the clinic: a simulation curriculum to improve outpatient safety.

    Science.gov (United States)

    Espey, Eve; Baty, Gillian; Rask, John; Chungtuyco, Michelle; Pereda, Brenda; Leeman, Lawrence

    2017-12-01

    Emergency response skills are essential when events such as seizure, anaphylaxis, or hemorrhage occur in the outpatient setting. As services and procedures increasingly move outside the hospital, training to manage complications may improve outcomes. The objective of this study was to evaluate a simulation-based curriculum in outpatient emergency management skills with the outcome measures of graded objective performance and learner self-efficacy. This pre- and postcurriculum study enrolled residents and fellows in Obstetrics and Gynecology and Family Medicine in a simulation-based, outpatient emergency management curriculum. Learners completed self-efficacy questionnaires and were videotaped managing 3 medical emergency scenarios (seizure, over-sedation/cardiopulmonary arrest, and hemorrhage) in the simulation laboratory both before and after completion of the curriculum. Evaluators who were blinded to training level scored the simulation performance videotapes using a graded rubric with critical action checklists. Scenario scores were assigned in 5 domains and globally. Paired t-tests were used to determine differences pre- and postcurriculum. Thirty residents completed the curriculum and pre- and postcurriculum testing. Subjects' objective performance scores improved in all 5 domains (Pimprovement. When scores were stratified by previous outpatient simulation experience, subjects with previous experience improved in all but management of excess sedation. Pre- and postcurriculum self-efficacy evaluations demonstrated improvement in all 7 measured areas: confidence, use of appropriate resources, communication skills, complex airway management, bag mask ventilation, resuscitation, and hemorrhage management. Self-efficacy assessment showed improvement in confidence managing outpatient emergencies (P=.001) and ability to communicate well in emergency situations (Pimproved both self-efficacy and objectively rated performance scores in management of outpatient medical

  2. Validation of a low dose simulation technique for computed tomography images.

    Directory of Open Access Journals (Sweden)

    Daniela Muenzel

    Full Text Available PURPOSE: Evaluation of a new software tool for generation of simulated low-dose computed tomography (CT images from an original higher dose scan. MATERIALS AND METHODS: Original CT scan data (100 mAs, 80 mAs, 60 mAs, 40 mAs, 20 mAs, 10 mAs; 100 kV of a swine were acquired (approved by the regional governmental commission for animal protection. Simulations of CT acquisition with a lower dose (simulated 10-80 mAs were calculated using a low-dose simulation algorithm. The simulations were compared to the originals of the same dose level with regard to density values and image noise. Four radiologists assessed the realistic visual appearance of the simulated images. RESULTS: Image characteristics of simulated low dose scans were similar to the originals. Mean overall discrepancy of image noise and CT values was -1.2% (range -9% to 3.2% and -0.2% (range -8.2% to 3.2%, respectively, p>0.05. Confidence intervals of discrepancies ranged between 0.9-10.2 HU (noise and 1.9-13.4 HU (CT values, without significant differences (p>0.05. Subjective observer evaluation of image appearance showed no visually detectable difference. CONCLUSION: Simulated low dose images showed excellent agreement with the originals concerning image noise, CT density values, and subjective assessment of the visual appearance of the simulated images. An authentic low-dose simulation opens up opportunity with regard to staff education, protocol optimization and introduction of new techniques.

  3. Wind Turbine Rotor Simulation via CFD Based Actuator Disc Technique Compared to Detailed Measurement

    Directory of Open Access Journals (Sweden)

    Esmail Mahmoodi

    2015-10-01

    Full Text Available In this paper, a generalized Actuator Disc (AD is used to model the wind turbine rotor of the MEXICO experiment, a collaborative European wind turbine project. The AD model as a combination of CFD technique and User Defined Functions codes (UDF, so-called UDF/AD model is used to simulate loads and performance of the rotor in three different wind speed tests. Distributed force on the blade, thrust and power production of the rotor as important designing parameters of wind turbine rotors are focused to model. A developed Blade Element Momentum (BEM theory as a code based numerical technique as well as a full rotor simulation both from the literature are included into the results to compare and discuss. The output of all techniques is compared to detailed measurements for validation, which led us to final conclusions.

  4. Assembly Line Efficiency Improvement by Using WITNESS Simulation Software

    Science.gov (United States)

    Yasir, A. S. H. M.; Mohamed, N. M. Z. N.

    2018-03-01

    In the nowadays-competitive world, efficiencies and the productivity of the assembly line are essential in manufacturing company. This paper demonstrates the study of the existing production line performance. The actual cycle time observed and recorded during the working process. The current layout was designed and analysed using Witness simulation software. The productivity and effectiveness for every single operator are measured to determine the operator idle time and busy time. Two new alternatives layout were proposed and analysed by using Witness simulation software to improve the performance of production activities. This research provided valuable and better understanding of production effectiveness by adjusting the line balancing. After analysing the data, simulation result from the current layout and the proposed plan later been tabulated to compare the improved efficiency and productivity. The proposed design plan has shown an increase in yield and productivity compared to the current arrangement. This research has been carried out in company XYZ, which is one of the automotive premises in Pahang, Malaysia.

  5. Monte Carlo simulation of tomography techniques using the platform Gate

    International Nuclear Information System (INIS)

    Barbouchi, Asma

    2007-01-01

    Simulations play a key role in functional imaging, with applications ranging from scanner design, scatter correction, protocol optimisation. GATE (Geant4 for Application Tomography Emission) is a platform for Monte Carlo Simulation. It is based on Geant4 to generate and track particles, to model geometry and physics process. Explicit modelling of time includes detector motion, time of flight, tracer kinetics. Interfaces to voxellised models and image reconstruction packages improve the integration of GATE in the global modelling cycle. In this work Monte Carlo simulations are used to understand and optimise the gamma camera's performances. We study the effect of the distance between source and collimator, the diameter of the holes and the thick of the collimator on the spatial resolution, energy resolution and efficiency of the gamma camera. We also study the reduction of simulation's time and implement a model of left ventricle in GATE. (Author). 7 refs

  6. Recent improvements in PIE-techniques at the IFE hot-laboratory

    International Nuclear Information System (INIS)

    Jenssen, Haakon Kristian

    1999-01-01

    The PIE-techniques at the IFE nuclear fuel section are continuously improved through upgrading of equipment and methods, e.g. image handling techniques and components utilised in data acquisition and editing techniques. To improve the quality or spatial resolution of neutron radiographs the normal technique was complemented with another method. The dysprosium foil/X-ray film technique is now supplemented with a track-etch recorder consisting of a cellulose nitrate film. For further examination the cellulose nitrate film can be digitised to allow electronic image treatment. Promising results were obtained with this technique on neutron radiographs, namely higher spatial resolution compared to the normal technique, high contrast and sharp neutron radiography images. The traditional one-axial profilometry of fuel rods were modified so that diameter/bow measurements are possible at several angular orientations during one acquisition sequence. This extension is very useful in several ways, for instance the built-in data symmetry of the method is used to check the correctness of the measurement results. Diameter and bow measurements give in addition detailed and complete information of canning irregularities and fuel rod profiles. PIE data are collected and compiled in an image file. Inspection and examination of the file information is possible through an ideal user-interface, i.e. Adobe photoshop software with navigator possibilities. An example incorporating PIE data acquired from a fuel rod exposed in a loss of coolant experiment is utilised for illustration of the user-interface and some of its possibilities (author) (ml)

  7. Lattice Boltzmann flow simulations with applications of reduced order modeling techniques

    KAUST Repository

    Brown, Donald

    2014-01-01

    With the recent interest in shale gas, an understanding of the flow mechanisms at the pore scale and beyond is necessary, which has attracted a lot of interest from both industry and academia. One of the suggested algorithms to help understand flow in such reservoirs is the Lattice Boltzmann Method (LBM). The primary advantage of LBM is its ability to approximate complicated geometries with simple algorithmic modificatoins. In this work, we use LBM to simulate the flow in a porous medium. More specifically, we use LBM to simulate a Brinkman type flow. The Brinkman law allows us to integrate fast free-flow and slow-flow porous regions. However, due to the many scales involved and complex heterogeneities of the rock microstructure, the simulation times can be long, even with the speed advantage of using an explicit time stepping method. The problem is two-fold, the computational grid must be able to resolve all scales and the calculation requires a steady state solution implying a large number of timesteps. To help reduce the computational complexity and total simulation times, we use model reduction techniques to reduce the dimension of the system. In this approach, we are able to describe the dynamics of the flow by using a lower dimensional subspace. In this work, we utilize the Proper Orthogonal Decomposition (POD) technique, to compute the dominant modes of the flow and project the solution onto them (a lower dimensional subspace) to arrive at an approximation of the full system at a lowered computational cost. We present a few proof-of-concept examples of the flow field and the corresponding reduced model flow field.

  8. Simulation of wind turbine wakes using the actuator line technique.

    Science.gov (United States)

    Sørensen, Jens N; Mikkelsen, Robert F; Henningson, Dan S; Ivanell, Stefan; Sarmast, Sasan; Andersen, Søren J

    2015-02-28

    The actuator line technique was introduced as a numerical tool to be employed in combination with large eddy simulations to enable the study of wakes and wake interaction in wind farms. The technique is today largely used for studying basic features of wakes as well as for making performance predictions of wind farms. In this paper, we give a short introduction to the wake problem and the actuator line methodology and present a study in which the technique is employed to determine the near-wake properties of wind turbines. The presented results include a comparison of experimental results of the wake characteristics of the flow around a three-bladed model wind turbine, the development of a simple analytical formula for determining the near-wake length behind a wind turbine and a detailed investigation of wake structures based on proper orthogonal decomposition analysis of numerically generated snapshots of the wake. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  9. Shower library technique for fast simulation of showers in calorimeters of the H1 experiment

    International Nuclear Information System (INIS)

    Raičević, N.; Glazov, A.; Zhokin, A.

    2013-01-01

    Fast simulation of showers in calorimeters is very important for particle physics analysis since shower simulation typically takes significant amount of the simulation time. At the same time, a simulation must reproduce experimental data in the best possible way. In this paper, a fast simulation of showers in two calorimeters of the H1 experiment is presented. High speed and good quality of shower simulation is achieved by using a shower library technique in which the detector response is simulated using a collection of stored showers for different particle types and topologies. The library is created using the GEANT programme. The fast simulation based on shower library is compared to the data collected by the H1 experiment

  10. Preflight screening techniques for centrifuge-simulated suborbital spaceflight.

    Science.gov (United States)

    Pattarini, James M; Blue, Rebecca S; Castleberry, Tarah L; Vanderploeg, James M

    2014-12-01

    Historically, space has been the venue of the healthy individual. With the advent of commercial spaceflight, we face the novel prospect of routinely exposing spaceflight participants (SPFs) with multiple comorbidities to the space environment. Preflight screening procedures must be developed to identify those individuals at increased risk during flight. We examined the responses of volunteers to centrifuge accelerations mimicking commercial suborbital spaceflight profiles to evaluate how potential SFPs might tolerate such forces. We evaluated our screening process for medical approval of subjects for centrifuge participation for applicability to commercial spaceflight operations. All registered subjects completed a medical questionnaire, physical examination, and electrocardiogram. Subjects with identified concerns including cardiopulmonary disease, hypertension, and diabetes were required to provide documentation of their conditions. There were 335 subjects who registered for the study, 124 who completed all prescreening, and 86 subjects who participated in centrifuge trials. Due to prior medical history, five subjects were disqualified, most commonly for psychiatric reasons or uncontrolled medical conditions. Of the subjects approved, four individuals experienced abnormal physiological responses to centrifuge profiles, including one back strain and three with anxiety reactions. The screening methods used were judged to be sufficient to identify individuals physically capable of tolerating simulated suborbital flight. Improved methods will be needed to identify susceptibility to anxiety reactions. While severe or uncontrolled disease was excluded, many subjects successfully participated in centrifuge trials despite medical histories of disease that are disqualifying under historical spaceflight screening regimes. Such screening techniques are applicable for use in future commercial spaceflight operations.

  11. Modeling and numerical techniques for high-speed digital simulation of nuclear power plants

    International Nuclear Information System (INIS)

    Wulff, W.; Cheng, H.S.; Mallen, A.N.

    1987-01-01

    Conventional computing methods are contrasted with newly developed high-speed and low-cost computing techniques for simulating normal and accidental transients in nuclear power plants. Six principles are formulated for cost-effective high-fidelity simulation with emphasis on modeling of transient two-phase flow coolant dynamics in nuclear reactors. Available computing architectures are characterized. It is shown that the combination of the newly developed modeling and computing principles with the use of existing special-purpose peripheral processors is capable of achieving low-cost and high-speed simulation with high-fidelity and outstanding user convenience, suitable for detailed reactor plant response analyses

  12. Health Worker Focused Distributed Simulation for Improving Capability of Health Systems in Liberia.

    Science.gov (United States)

    Gale, Thomas C E; Chatterjee, Arunangsu; Mellor, Nicholas E; Allan, Richard J

    2016-04-01

    The main goal of this study was to produce an adaptable learning platform using virtual learning and distributed simulation, which can be used to train health care workers, across a wide geographical area, key safety messages regarding infection prevention control (IPC). A situationally responsive agile methodology, Scrum, was used to develop a distributed simulation module using short 1-week iterations and continuous synchronous plus asynchronous communication including end users and IPC experts. The module contained content related to standard IPC precautions (including handwashing techniques) and was structured into 3 distinct sections related to donning, doffing, and hazard perception training. Using Scrum methodology, we were able to link concepts applied to best practices in simulation-based medical education (deliberate practice, continuous feedback, self-assessment, and exposure to uncommon events), pedagogic principles related to adult learning (clear goals, contextual awareness, motivational features), and key learning outcomes regarding IPC, as a rapid response initiative to the Ebola outbreak in West Africa. Gamification approach has been used to map learning mechanics to enhance user engagement. The developed IPC module demonstrates how high-frequency, low-fidelity simulations can be rapidly designed using scrum-based agile methodology. Analytics incorporated into the tool can help demonstrate improved confidence and competence of health care workers who are treating patients within an Ebola virus disease outbreak region. These concepts could be used in a range of evolving disasters where rapid development and communication of key learning messages are required.

  13. Towards improved hydrologic predictions using data assimilation techniques for water resource management at the continental scale

    Science.gov (United States)

    Naz, Bibi; Kurtz, Wolfgang; Kollet, Stefan; Hendricks Franssen, Harrie-Jan; Sharples, Wendy; Görgen, Klaus; Keune, Jessica; Kulkarni, Ketan

    2017-04-01

    More accurate and reliable hydrologic simulations are important for many applications such as water resource management, future water availability projections and predictions of extreme events. However, simulation of spatial and temporal variations in the critical water budget components such as precipitation, snow, evaporation and runoff is highly uncertain, due to errors in e.g. model structure and inputs (hydrologic parameters and forcings). In this study, we use data assimilation techniques to improve the predictability of continental-scale water fluxes using in-situ measurements along with remotely sensed information to improve hydrologic predications for water resource systems. The Community Land Model, version 3.5 (CLM) integrated with the Parallel Data Assimilation Framework (PDAF) was implemented at spatial resolution of 1/36 degree (3 km) over the European CORDEX domain. The modeling system was forced with a high-resolution reanalysis system COSMO-REA6 from Hans-Ertel Centre for Weather Research (HErZ) and ERA-Interim datasets for time period of 1994-2014. A series of data assimilation experiments were conducted to assess the efficiency of assimilation of various observations, such as river discharge data, remotely sensed soil moisture, terrestrial water storage and snow measurements into the CLM-PDAF at regional to continental scales. This setup not only allows to quantify uncertainties, but also improves streamflow predictions by updating simultaneously model states and parameters utilizing observational information. The results from different regions, watershed sizes, spatial resolutions and timescales are compared and discussed in this study.

  14. 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.

  15. A Qualitative Analysis of the Neutron Population in Fresh and Spent Fuel Assemblies during Simulated Interrogation using the Differential Die-Away Technique

    International Nuclear Information System (INIS)

    Lundkvista, Niklas; Goodsell, Alison V.; Grapea, Sophie; Hendricksb, John S.; Henzlb, Vladimir; Swinhoe, Martyn T.; Tobin, Stephen J.

    2015-01-01

    Monte Carlo simulations were performed for the differential die-away (DDA) technique to analyse the time-dependent behaviour of the neutron population in fresh and spent nuclear fuel assemblies as part of the Next Generation Safeguards Initiative Spent Fuel (NGSI-SF) Project. Simulations were performed to investigate both a possibly portable as well as a permanent DDA instrument. Taking advantage of a custom made modification to the MCNPX code, the variation in the neutron population, simultaneously in time and space, was examined. The motivation for this research was to improve the design of the DDA instrument, as it is being considered for possible deployment at the Central Storage of Spent Nuclear Fuel and Encapsulation Plant in Sweden (Clab), as well as to assist in the interpretation of the both simulated and measured signals.

  16. Improved climate risk simulations for rice in arid environments.

    Directory of Open Access Journals (Sweden)

    Pepijn A J van Oort

    Full Text Available We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potential yields with yields simulated with default ORYZA2000, with modified subversions of ORYZA2000 and with ORYZA_S, a model developed for the region of interest in the 1990s. Rice variety 'IR64' was sown monthly 15-times in a row in two locations in Senegal. The Senegal River Valley is located in the Sahel, near the Sahara desert with extreme temperatures during day and night. The existing subroutines underestimated cold stress and overestimated heat stress. Forcing the model to use observed spikelet number and phenology and replacing the existing heat and cold subroutines improved accuracy of yield simulation from EF = -0.32 to EF =0.70 (EF is modelling efficiency. The main causes of improved accuracy were that the new model subversions take into account transpirational cooling (which is high in arid environments and early morning flowering for heat sterility, and minimum rather than average temperature for cold sterility. Simulations were less accurate when also spikelet number and phenology were simulated. Model efficiency was 0.14 with new heat and cold routines and improved to 0.48 when using new cardinal temperatures for phenology and early leaf growth. The new adapted subversion of ORYZA2000 offers a powerful analytic tool for climate change impact assessment and cropping calendar optimisation in arid regions.

  17. Advanced Atmospheric Ensemble Modeling Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Chiswell, S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Kurzeja, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Maze, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Viner, B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Werth, D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-29

    Ensemble modeling (EM), the creation of multiple atmospheric simulations for a given time period, has become an essential tool for characterizing uncertainties in model predictions. We explore two novel ensemble modeling techniques: (1) perturbation of model parameters (Adaptive Programming, AP), and (2) data assimilation (Ensemble Kalman Filter, EnKF). The current research is an extension to work from last year and examines transport on a small spatial scale (<100 km) in complex terrain, for more rigorous testing of the ensemble technique. Two different release cases were studied, a coastal release (SF6) and an inland release (Freon) which consisted of two release times. Observations of tracer concentration and meteorology are used to judge the ensemble results. In addition, adaptive grid techniques have been developed to reduce required computing resources for transport calculations. Using a 20- member ensemble, the standard approach generated downwind transport that was quantitatively good for both releases; however, the EnKF method produced additional improvement for the coastal release where the spatial and temporal differences due to interior valley heating lead to the inland movement of the plume. The AP technique showed improvements for both release cases, with more improvement shown in the inland release. This research demonstrated that transport accuracy can be improved when models are adapted to a particular location/time or when important local data is assimilated into the simulation and enhances SRNL’s capability in atmospheric transport modeling in support of its current customer base and local site missions, as well as our ability to attract new customers within the intelligence community.

  18. Medical simulation-based education improves medicos' clinical skills.

    Science.gov (United States)

    Wang, Zhaoming; Liu, Qiaoyu; Wang, Hai

    2013-03-01

    Clinical skill is an essential part of clinical medicine and plays quite an important role in bridging medicos and physicians. Due to the realities in China, traditional medical education is facing many challenges. There are few opportunities for students to practice their clinical skills and their dexterities are generally at a low level. Medical simulation-based education is a new teaching modality and helps to improve medicos' clinical skills to a large degree. Medical simulation-based education has many significant advantages and will be further developed and applied.

  19. improvement of digital image watermarking techniques based on FPGA implementation

    International Nuclear Information System (INIS)

    EL-Hadedy, M.E

    2006-01-01

    digital watermarking provides the ownership of a piece of digital data by marking the considered data invisibly or visibly. this can be used to protect several types of multimedia objects such as audio, text, image and video. this thesis demonstrates the different types of watermarking techniques such as (discrete cosine transform (DCT) and discrete wavelet transform (DWT) and their characteristics. then, it classifies these techniques declaring their advantages and disadvantages. an improved technique with distinguished features, such as peak signal to noise ratio ( PSNR) and similarity ratio (SR) has been introduced. the modified technique has been compared with the other techniques by measuring heir robustness against differ attacks. finally, field programmable gate arrays (FPGA) based implementation and comparison, for the proposed watermarking technique have been presented and discussed

  20. Real time simulation techniques in Taiwan - Maanshan compact simulator

    International Nuclear Information System (INIS)

    Liang, K.-S.; Chuang, Y.-M.; Ko, H.-T.

    2004-01-01

    Recognizing the demand and potential market of simulators in various industries, a special project for real time simulation technology transfer was initiated in Taiwan in 1991. In this technology transfer program, the most advanced real-time dynamic modules for nuclear power simulation were introduced. Those modules can be divided into two categories; one is modeling related to catch dynamic response of each system, and the other is computer related to provide special real time computing environment and man-machine interface. The modeling related modules consist of the thermodynamic module, the three-dimensional core neutronics module and the advanced balance of plant module. As planned in the project, the technology transfer team should build a compact simulator for the Maanshan power plant before the end of the project to demonstrate the success of the technology transfer program. The compact simulator was designed to support the training from the regular full scope simulator which was already equipped in the Maanshan plant. The feature of this compact simulator focused on providing know-why training by the enhanced graphic display. The potential users were identified as senior operators, instructors and nuclear engineers. Total about 13 important systems were covered in the scope of the compact simulator, and multi-graphic displays from three color monitors mounted on the 10 feet compact panel were facilitated to help the user visualize detailed phenomena under scenarios of interest. (author)

  1. A Simple Ensemble Simulation Technique for Assessment of Future Variations in Specific High-Impact Weather Events

    Science.gov (United States)

    Taniguchi, Kenji

    2018-04-01

    To investigate future variations in high-impact weather events, numerous samples are required. For the detailed assessment in a specific region, a high spatial resolution is also required. A simple ensemble simulation technique is proposed in this paper. In the proposed technique, new ensemble members were generated from one basic state vector and two perturbation vectors, which were obtained by lagged average forecasting simulations. Sensitivity experiments with different numbers of ensemble members, different simulation lengths, and different perturbation magnitudes were performed. Experimental application to a global warming study was also implemented for a typhoon event. Ensemble-mean results and ensemble spreads of total precipitation, atmospheric conditions showed similar characteristics across the sensitivity experiments. The frequencies of the maximum total and hourly precipitation also showed similar distributions. These results indicate the robustness of the proposed technique. On the other hand, considerable ensemble spread was found in each ensemble experiment. In addition, the results of the application to a global warming study showed possible variations in the future. These results indicate that the proposed technique is useful for investigating various meteorological phenomena and the impacts of global warming. The results of the ensemble simulations also enable the stochastic evaluation of differences in high-impact weather events. In addition, the impacts of a spectral nudging technique were also examined. The tracks of a typhoon were quite different between cases with and without spectral nudging; however, the ranges of the tracks among ensemble members were comparable. It indicates that spectral nudging does not necessarily suppress ensemble spread.

  2. A Review of Endoscopic Simulation: Current Evidence on Simulators and Curricula.

    Science.gov (United States)

    King, Neil; Kunac, Anastasia; Merchant, Aziz M

    2016-01-01

    Upper and lower endoscopy is an important tool that is being utilized more frequently by general surgeons. Training in therapeutic endoscopic techniques has become a mandatory requirement for general surgery residency programs in the United States. The Fundamentals of Endoscopic Surgery has been developed to train and assess competency in these advanced techniques. Simulation has been shown to increase the skill and learning curve of trainees in other surgical disciplines. Several types of endoscopy simulators are commercially available; mechanical trainers, animal based, and virtual reality or computer-based simulators all have their benefits and limitations. However they have all been shown to improve trainee's endoscopic skills. Endoscopic simulators will play a critical role as part of a comprehensive curriculum designed to train the next generation of surgeons. We reviewed recent literature related to the various types of endoscopic simulators and their use in an educational curriculum, and discuss the relevant findings. Copyright © 2015 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  3. Mining MaNGA for Merging Galaxies: A New Imaging and Kinematic Technique from Hydrodynamical Simulations

    Science.gov (United States)

    Nevin, Becky; Comerford, Julia M.; Blecha, Laura

    2018-06-01

    Merging galaxies play a key role in galaxy evolution, and progress in our understanding of galaxy evolution is slowed by the difficulty of making accurate galaxy merger identifications. Mergers are typically identified using imaging alone, which has its limitations and biases. With the growing popularity of integral field spectroscopy (IFS), it is now possible to use kinematic signatures to improve galaxy merger identifications. I use GADGET-3 hydrodynamical simulations of merging galaxies with the radiative transfer code SUNRISE, the later of which enables me to apply the same analysis to simulations and observations. From the simulated galaxies, I have developed the first merging galaxy classification scheme that is based on kinematics and imaging. Utilizing a Linear Discriminant Analysis tool, I have determined which kinematic and imaging predictors are most useful for identifying mergers of various merger parameters (such as orientation, mass ratio, gas fraction, and merger stage). I will discuss the strengths and limitations of the classification technique and then my initial results for applying the classification to the >10,000 observed galaxies in the MaNGA (Mapping Nearby Galaxies at Apache Point) IFS survey. Through accurate identification of merging galaxies in the MaNGA survey, I will advance our understanding of supermassive black hole growth in galaxy mergers and other open questions related to galaxy evolution.

  4. Novel prostate brachytherapy technique: Improved dosimetric and clinical outcome

    International Nuclear Information System (INIS)

    Nobes, Jenny P.; Khaksar, Sara J.; Hawkins, Maria A.; Cunningham, Melanie J.; Langley, Stephen E.M.; Laing, Robert W.

    2008-01-01

    Purpose: Erectile dysfunction following prostate brachytherapy is reported to be related to dose received by the penile bulb. To minimise this, whilst preserving prostate dosimetry, we have developed a technique for I-125 seed brachytherapy using both stranded seeds and loose seeds delivered with a Mick applicator, and implanted via the sagittal plane on trans-rectal ultrasound. Materials and methods: Post-implant dosimetry and potency rates were compared in 120 potent patients. In Group 1, 60 patients were treated using a conventional technique of seeds implanted in a modified-uniform distribution. From January 2005, a novel technique was developed using stranded seeds peripherally and centrally distributed loose seeds implanted via a Mick applicator (Group 2). The latter technique allows greater flexibility when implanting the seeds at the apex. Each patient was prescribed a minimum peripheral dose of 145 Gy. No patients received external beam radiotherapy or hormone treatment. There was no significant difference in age or pre-implant potency score (mean IIEF-5 score 22.4 vs. 22.6, p = 0.074) between the two groups. Results: The new technique delivers lower penile bulb doses (D 25 as %mPD - Group 1: 61.2 ± 35.7, Group 2: 29.7 ± 16.0, p 50 as %mPD - Group 1: 45.8 ± 26.9, Group 2: 21.4 ± 11.7, p 90 - Group 1: 147 Gy ± 21.1, Group 2: 155 Gy ± 16.7, p = 0.03). At 2 years, the potency rate was also improved: Group 1: 61.7%; Group 2: 83.3% (p = 0.008). Conclusions: In this study, the novel brachytherapy technique using both peripheral stranded seeds and central loose seeds delivered via a Mick applicator results in a lower penile bulb dose whilst improving prostate dosimetry, and may achieve higher potency rates

  5. [Simulation in pediatric surgery].

    Science.gov (United States)

    Becmeur, François; Lacreuse, Isabelle; Soler, Luc

    2011-11-01

    Simulation in paediatric surgery is essential for educational, ethical, medicolegal and economic reasons, and is particularly important for rare procedures. There are three different levels of simulation:--simulation of basic techniques in order to learn or improve surgical skills (dissection, intracorporeal knots, etc.);--preparation for surgery using virtual reality, to perfect and test various procedures on a virtual patient, and to determine the best approaches for individual cases;--behavioral simulation underlines the importance of the preoperative check-list and facilitates crisis management (complications, conversion, etc.).

  6. Student’s Perceptions on Simulation as Part of Experiential Learning in Approaches, Methods, and Techniques (AMT Course

    Directory of Open Access Journals (Sweden)

    Marselina Karina Purnomo

    2017-03-01

    Full Text Available Simulation is a part of Experiential Learning which represents certain real-life events. In this study, simulation is used as a learning activity in Approaches, Methods, and Techniques (AMT course which is one of the courses in English Language Education Study Program (ELESP of Sanata Dharma University. Since simulation represents the real-life events, it encourages students to apply the approaches, methods, and techniques being studied based on the real-life classroom. Several experts state that students are able to involve their personal experiences through simulation which additionally is believed to create a meaningful learning in the class. This study aimed to discover ELESP students’ perceptions toward simulation as a part of Experiential Learning in AMT course. From the findings, it could be inferred that students agreed that simulation in class was important for students’ learning for it formed a meaningful learning in class.  DOI: https://doi.org/10.24071/llt.2017.200104

  7. Tailored Cloze: Improved with Classical Item Analysis Techniques.

    Science.gov (United States)

    Brown, James Dean

    1988-01-01

    The reliability and validity of a cloze procedure used as an English-as-a-second-language (ESL) test in China were improved by applying traditional item analysis and selection techniques. The 'best' test items were chosen on the basis of item facility and discrimination indices, and were administered as a 'tailored cloze.' 29 references listed.…

  8. Advanced particle-in-cell simulation techniques for modeling the Lockheed Martin Compact Fusion Reactor

    Science.gov (United States)

    Welch, Dale; Font, Gabriel; Mitchell, Robert; Rose, David

    2017-10-01

    We report on particle-in-cell developments of the study of the Compact Fusion Reactor. Millisecond, two and three-dimensional simulations (cubic meter volume) of confinement and neutral beam heating of the magnetic confinement device requires accurate representation of the complex orbits, near perfect energy conservation, and significant computational power. In order to determine initial plasma fill and neutral beam heating, these simulations include ionization, elastic and charge exchange hydrogen reactions. To this end, we are pursuing fast electromagnetic kinetic modeling algorithms including a two implicit techniques and a hybrid quasi-neutral algorithm with kinetic ions. The kinetic modeling includes use of the Poisson-corrected direct implicit, magnetic implicit, as well as second-order cloud-in-cell techniques. The hybrid algorithm, ignoring electron inertial effects, is two orders of magnitude faster than kinetic but not as accurate with respect to confinement. The advantages and disadvantages of these techniques will be presented. Funded by Lockheed Martin.

  9. A new simple technique for improving the random properties of chaos-based cryptosystems

    Science.gov (United States)

    Garcia-Bosque, M.; Pérez-Resa, A.; Sánchez-Azqueta, C.; Celma, S.

    2018-03-01

    A new technique for improving the security of chaos-based stream ciphers has been proposed and tested experimentally. This technique manages to improve the randomness properties of the generated keystream by preventing the system to fall into short period cycles due to digitation. In order to test this technique, a stream cipher based on a Skew Tent Map algorithm has been implemented on a Virtex 7 FPGA. The randomness of the keystream generated by this system has been compared to the randomness of the keystream generated by the same system with the proposed randomness-enhancement technique. By subjecting both keystreams to the National Institute of Standards and Technology (NIST) tests, we have proved that our method can considerably improve the randomness of the generated keystreams. In order to incorporate our randomness-enhancement technique, only 41 extra slices have been needed, proving that, apart from effective, this method is also efficient in terms of area and hardware resources.

  10. Improvement of computer complex and interface system for compact nuclear simulator

    International Nuclear Information System (INIS)

    Lee, D. Y.; Park, W. M.; Cha, K. H.; Jung, C. H.; Park, J. C.

    1999-01-01

    CNS(Compact Nuclear Simulator) was developed at the end of 1980s, and have been used as training simulator for staffs of KAERI during 10 years. The operator panel interface cards and the graphic interface cards were designed with special purpose only for CNS. As these interface cards were worn out for 10 years, it was very difficult to get spare parts and to repair them. And the interface cards were damaged by over current happened by shortage of lamp in the operator panel. To solve these problem, the project 'Improvement of Compact Nuclear Simulator' was started from 1997. This paper only introduces about the improvement of computer complex and interface system

  11. Operational analysis and improvement of a spent nuclear fuel handling and treatment facility using discrete event simulation

    International Nuclear Information System (INIS)

    Garcia, H.E.

    2000-01-01

    Spent nuclear fuel handling and treatment often require facilities with a high level of operational complexity. Simulation models can reveal undesirable characteristics and production problems before they become readily apparent during system operations. The value of this approach is illustrated here through an operational study, using discrete event modeling techniques, to analyze the Fuel Conditioning Facility at Argonne National Laboratory and to identify enhanced nuclear waste treatment configurations. The modeling approach and results of what-if studies are discussed. An example on how to improve productivity is presented.

  12. Using ICT techniques for improving mechatronic systems' dependability

    Science.gov (United States)

    Miron, Emanuel; Silva, João P. M. A.; Machado, José; Olaru, Dumitru; Prisacaru, Gheorghe

    2013-10-01

    The use of analysis techniques for industrial controller's analysis, such as Simulation and Formal Verification, is complex on industrial context. This complexity is due to the fact that such techniques require sometimes high investment in specific skilled human resources that have sufficient theoretical knowledge in those domains. This paper aims, mainly, to show that it is possible to obtain a timed automata model for formal verification purposes, considering the CAD model of a mechanical component. This systematic approach can be used, by companies, for the analysis of industrial controllers programs. For this purpose, it is discussed, in the paper, the best way to systematize these procedures, and this paper describes, only, the first step of a complex process and promotes a discussion of the main difficulties that can be found and a possibility for handle those difficulties. A library for formal verification purposes is obtained from original 3D CAD models using Software as a Service platform (SaaS) that, nowadays, has become a common deliverable model for many applications, because SaaS is typically accessed by users via internet access.

  13. Using Direct Sub-Level Entity Access to Improve Nuclear Stockpile Simulation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Parker, Robert Y. [Brigham Young Univ., Provo, UT (United States)

    1999-08-01

    Direct sub-level entity access is a seldom-used technique in discrete-event simulation modeling that addresses the accessibility of sub-level entity information. The technique has significant advantages over more common, alternative modeling methods--especially where hierarchical entity structures are modeled. As such, direct sub-level entity access is often preferable in modeling nuclear stockpile, life-extension issues, an area to which it has not been previously applied. Current nuclear stockpile, life-extension models were demonstrated to benefit greatly from the advantages of direct sub-level entity access. In specific cases, the application of the technique resulted in models that were up to 10 times faster than functionally equivalent models where alternative techniques were applied. Furthermore, specific implementations of direct sub-level entity access were observed to be more flexible, efficient, functional, and scalable than corresponding implementations using common modeling techniques. Common modeling techniques (''unbatch/batch'' and ''attribute-copying'') proved inefficient and cumbersome in handling many nuclear stockpile modeling complexities, including multiple weapon sites, true defect analysis, and large numbers of weapon and subsystem types. While significant effort was required to enable direct sub-level entity access in the nuclear stockpile simulation models, the enhancements were worth the effort--resulting in more efficient, more capable, and more informative models that effectively addressed the complexities of the nuclear stockpile.

  14. Application of simulation techniques for accident management training in nuclear power plants

    International Nuclear Information System (INIS)

    2003-05-01

    core. These capabilities include the optimized use of design margins as well as complementary measures for the prevention of accident progression, its monitoring, and the mitigation of severe accidents. Finally, level 5 includes off-site emergency response measures, the objective of which is to mitigate the radiological consequences of significant releases of radioactive material. Accident management is defined in the IAEA Safety Report on Development and Implementation of Accident Management Programmes in Nuclear Power Plants. The IAEA definitions are in line with the definitions of severe accident management in OECD/NEA documents as given, for example. This report describes simulation techniques used in the training of personnel involved in accident management of NPPs. This concerns both the plant personnel and the persons involved in the management of off-site releases. The report pertains to light water reactors (LWRs) and pressurized heavy water reactors (PHWRs), but it can equally be applied to power reactors of other types. The report is intended for use by experts responsible for planning, developing, executing or supervising the training of personnel involved in the implementation of AMPs in NPPs. It concentrates on existing techniques, but future prospects are also discussed. Various simulation techniques are considered, from incorporating graphical interfaces into existing severe accident codes to full-scope replica simulators. Both preventive and mitigative accident management measures, different training levels and different target personnel groups are taken into account. Based on the available information compiled worldwide, present views on the applicability of simulation techniques for the training of personnel involved in accident management are provided in this report. Apart from the introduction, this report consists of four sections and three appendices. In Section 2, specific aspects of accident management are summarized. Basic approaches in the

  15. FPGA-accelerated simulation of computer systems

    CERN Document Server

    Angepat, Hari; Chung, Eric S; Hoe, James C; Chung, Eric S

    2014-01-01

    To date, the most common form of simulators of computer systems are software-based running on standard computers. One promising approach to improve simulation performance is to apply hardware, specifically reconfigurable hardware in the form of field programmable gate arrays (FPGAs). This manuscript describes various approaches of using FPGAs to accelerate software-implemented simulation of computer systems and selected simulators that incorporate those techniques. More precisely, we describe a simulation architecture taxonomy that incorporates a simulation architecture specifically designed f

  16. Improvement of the NSSS T/H Module ARTS for Enhancing the Simulation Fidelity of YGN no 1/2 Simulator

    International Nuclear Information System (INIS)

    Seo, In Yong; Lee, Myung Soo; Lee, Yong Kwan; Suh, Jae Seung; Jeun, Gyoo Dong

    2006-01-01

    KEPRI(Korea Electric Power Research Institute) and KAERI(Korea Atomic Energy Research Institute) developed a NSSS (Nuclear Steam Supply System) T/H (Thermal-Hydraulic) module (named ARTS) based on the best-estimate code RETRAN-3D for the KNPEC-2 full-scope simulator in 2001. Although ARTS can simulate the most transients in real-time, and its robustness is ensured, real-time calculation and robustness can fail for large break loss-of-coolant accident (LBLOCA) and long term, two-phase transients. In order to improve its robustness, ARTS equipped with the backup calculation module to be used whenever a regular ARTS module fails to calculate. When the symptom for the failure of T/H module is detected, the main ARTS module is replaced with the backup module for the calculation of primary and secondary reactor system although most failures of ARTS occur in the calculation of the primary system especially for LBLOCA simulation. The sudden transition from the main ARTS module to the backup module can exhibit the discontinuity of simulation of secondary system on rare occasions. To mitigate the simulation discontinuity, we have improved the backup module of ARTS. The performance of a new approach has been illustrated by the non-integrated standalone test. The improved ARTS module will be incorporated into YGN no. 1/2 simulator and evaluated its performance in the real simulator environment. This paper presents the brief description of a new backup calculation strategy and the simulation results of LOCA to evaluate the performance of a new backup strategy in standalone test environment

  17. Novel Oversampling Technique for Improving Signal-to-Quantization Noise Ratio on Accelerometer-Based Smart Jerk Sensors in CNC Applications.

    Science.gov (United States)

    Rangel-Magdaleno, Jose J; Romero-Troncoso, Rene J; Osornio-Rios, Roque A; Cabal-Yepez, Eduardo

    2009-01-01

    Jerk monitoring, defined as the first derivative of acceleration, has become a major issue in computerized numeric controlled (CNC) machines. Several works highlight the necessity of measuring jerk in a reliable way for improving production processes. Nowadays, the computation of jerk is done by finite differences of the acceleration signal, computed at the Nyquist rate, which leads to low signal-to-quantization noise ratio (SQNR) during the estimation. The novelty of this work is the development of a smart sensor for jerk monitoring from a standard accelerometer, which has improved SQNR. The proposal is based on oversampling techniques that give a better estimation of jerk than that produced by a Nyquist-rate differentiator. Simulations and experimental results are presented to show the overall methodology performance.

  18. Parallel sparse direct solver for integrated circuit simulation

    CERN Document Server

    Chen, Xiaoming; Yang, Huazhong

    2017-01-01

    This book describes algorithmic methods and parallelization techniques to design a parallel sparse direct solver which is specifically targeted at integrated circuit simulation problems. The authors describe a complete flow and detailed parallel algorithms of the sparse direct solver. They also show how to improve the performance by simple but effective numerical techniques. The sparse direct solver techniques described can be applied to any SPICE-like integrated circuit simulator and have been proven to be high-performance in actual circuit simulation. Readers will benefit from the state-of-the-art parallel integrated circuit simulation techniques described in this book, especially the latest parallel sparse matrix solution techniques. · Introduces complicated algorithms of sparse linear solvers, using concise principles and simple examples, without complex theory or lengthy derivations; · Describes a parallel sparse direct solver that can be adopted to accelerate any SPICE-like integrated circuit simulato...

  19. Strategies in edge plasma simulation using adaptive dynamic nodalization techniques

    International Nuclear Information System (INIS)

    Kainz, A.; Weimann, G.; Kamelander, G.

    2003-01-01

    A wide span of steady-state and transient edge plasma processes simulation problems require accurate discretization techniques and can then be treated with Finite Element (FE) and Finite Volume (FV) methods. The software used here to meet these meshing requirements is a 2D finite element grid generator. It allows to produce adaptive unstructured grids taking into consideration the flux surface characteristics. To comply with the common mesh handling features of FE/FV packages, some options have been added to the basic generation tool. These enhancements include quadrilateral meshes without non-regular transition elements obtained by substituting them by transition constructions consisting of regular quadrilateral elements. Furthermore triangular grids can be created with one edge parallel to the magnetic field and modified by the basic adaptation/realignment techniques. Enhanced code operation properties and processing capabilities are expected. (author)

  20. Simulation technique for slurries interacting with moving parts and deformable solids with applications

    Science.gov (United States)

    Mutabaruka, Patrick; Kamrin, Ken

    2018-04-01

    A numerical method for particle-laden fluids interacting with a deformable solid domain and mobile rigid parts is proposed and implemented in a full engineering system. The fluid domain is modeled with a lattice Boltzmann representation, the particles and rigid parts are modeled with a discrete element representation, and the deformable solid domain is modeled using a Lagrangian mesh. The main issue of this work, since separately each of these methods is a mature tool, is to develop coupling and model-reduction approaches in order to efficiently simulate coupled problems of this nature, as in various geological and engineering applications. The lattice Boltzmann method incorporates a large eddy simulation technique using the Smagorinsky turbulence model. The discrete element method incorporates spherical and polyhedral particles for stiff contact interactions. A neo-Hookean hyperelastic model is used for the deformable solid. We provide a detailed description of how to couple the three solvers within a unified algorithm. The technique we propose for rubber modeling/coupling exploits a simplification that prevents having to solve a finite-element problem at each time step. We also developed a technique to reduce the domain size of the full system by replacing certain zones with quasi-analytic solutions, which act as effective boundary conditions for the lattice Boltzmann method. The major ingredients of the routine are separately validated. To demonstrate the coupled method in full, we simulate slurry flows in two kinds of piston valve geometries. The dynamics of the valve and slurry are studied and reported over a large range of input parameters.

  1. Optimisation of 12 MeV electron beam simulation using variance reduction technique

    International Nuclear Information System (INIS)

    Jayamani, J; Aziz, M Z Abdul; Termizi, N A S Mohd; Kamarulzaman, F N Mohd

    2017-01-01

    Monte Carlo (MC) simulation for electron beam radiotherapy consumes a long computation time. An algorithm called variance reduction technique (VRT) in MC was implemented to speed up this duration. This work focused on optimisation of VRT parameter which refers to electron range rejection and particle history. EGSnrc MC source code was used to simulate (BEAMnrc code) and validate (DOSXYZnrc code) the Siemens Primus linear accelerator model with the non-VRT parameter. The validated MC model simulation was repeated by applying VRT parameter (electron range rejection) that controlled by global electron cut-off energy 1,2 and 5 MeV using 20 × 10 7 particle history. 5 MeV range rejection generated the fastest MC simulation with 50% reduction in computation time compared to non-VRT simulation. Thus, 5 MeV electron range rejection utilized in particle history analysis ranged from 7.5 × 10 7 to 20 × 10 7 . In this study, 5 MeV electron cut-off with 10 × 10 7 particle history, the simulation was four times faster than non-VRT calculation with 1% deviation. Proper understanding and use of VRT can significantly reduce MC electron beam calculation duration at the same time preserving its accuracy. (paper)

  2. Improving SWAT for simulating water and carbon fluxes of forest ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qichun; Zhang, Xuesong

    2016-11-01

    As a widely used watershed model for assessing impacts of anthropogenic and natural disturbances on water quantity and quality, the Soil and Water Assessment Tool (SWAT) has not been extensively tested in simulating water and carbon fluxes of forest ecosystems. Here, we examine SWAT simulations of evapotranspiration (ET), net primary productivity (NPP), net ecosystem exchange (NEE), and plant biomass at ten AmeriFlux forest sites across the U.S. We identify unrealistic radiation use efficiency (Bio_E), large leaf to biomass fraction (Bio_LEAF), and missing phosphorus supply from parent material weathering as the primary causes for the inadequate performance of the default SWAT model in simulating forest dynamics. By further revising the relevant parameters and processes, SWAT’s performance is substantially improved. Based on the comparison between the improved SWAT simulations and flux tower observations, we discuss future research directions for further enhancing model parameterization and representation of water and carbon cycling for forests.

  3. An improved visualization-based force-measurement technique for short-duration hypersonic facilities

    Energy Technology Data Exchange (ETDEWEB)

    Laurence, Stuart J.; Karl, Sebastian [Institute of Aerodynamics and Flow Technology, Spacecraft Section, German Aerospace Center (DLR), Goettingen (Germany)

    2010-06-15

    This article is concerned with describing and exploring the limitations of an improved version of a recently proposed visualization-based technique for the measurement of forces and moments in short-duration hypersonic wind tunnels. The technique is based on tracking the motion of a free-flying body over a sequence of high-speed visualizations; while this idea is not new in itself, the use of high-speed digital cinematography combined with a highly accurate least-squares tracking algorithm allows improved results over what have been previously possible with such techniques. The technique precision is estimated through the analysis of artificially constructed and experimental test images, and the resulting error in acceleration measurements is characterized. For wind-tunnel scale models, position measurements to within a few microns are shown to be readily attainable. Image data from two previous experimental studies in the T5 hypervelocity shock tunnel are then reanalyzed with the improved technique: the uncertainty in the mean drag acceleration is shown to be reduced to the order of the flow unsteadiness, 2-3%, and time-resolved acceleration measurements are also shown to be possible. The response time of the technique for the configurations studied is estimated to be {proportional_to}0.5 ms. Comparisons with computations using the DLR TAU code also yield agreement to within the overall experimental uncertainty. Measurement of the pitching moment for blunt geometries still appears challenging, however. (orig.)

  4. Structured building model reduction toward parallel simulation

    Energy Technology Data Exchange (ETDEWEB)

    Dobbs, Justin R. [Cornell University; Hencey, Brondon M. [Cornell University

    2013-08-26

    Building energy model reduction exchanges accuracy for improved simulation speed by reducing the number of dynamical equations. Parallel computing aims to improve simulation times without loss of accuracy but is poorly utilized by contemporary simulators and is inherently limited by inter-processor communication. This paper bridges these disparate techniques to implement efficient parallel building thermal simulation. We begin with a survey of three structured reduction approaches that compares their performance to a leading unstructured method. We then use structured model reduction to find thermal clusters in the building energy model and allocate processing resources. Experimental results demonstrate faster simulation and low error without any interprocessor communication.

  5. Urban Road Traffic Simulation Techniques

    Directory of Open Access Journals (Sweden)

    Ana Maria Nicoleta Mocofan

    2011-09-01

    Full Text Available For achieving a reliable traffic control system it is necessary to first establish a network parameter evaluation system and also a simulation system for the traffic lights plan. In 40 years of history, the computer aided traffic simulation has developed from a small research group to a large scale technology for traffic systems planning and development. In the following thesis, a presentation of the main modeling and simulation road traffic applications will be provided, along with their utility, as well as the practical application of one of the models in a case study.

  6. Embedding patient simulation in a pediatric cardiology rotation: a unique opportunity for improving resident education.

    Science.gov (United States)

    Mohan, Shaun; Follansbee, Christopher; Nwankwo, Ugonna; Hofkosh, Dena; Sherman, Frederick S; Hamilton, Melinda F

    2015-01-01

    High-fidelity patient simulation (HFPS) has been used in medical education to bridge gaps in medical knowledge and clinical skills. Few studies have analyzed the impact of HFPS in subspecialty rotations for pediatric residents. We hypothesized that pediatric residents exposed to HFPS with a structured content curriculum would perform better on a case quiz than residents without exposure to HFPS. Prospective randomized controlled Tertiary-care free standing children's hospital During a cardiology rotation, senior pediatric residents completed an online pediatric cardiology curriculum and a cardiology quiz. After randomization into two groups, the study group participated in a fully debriefed HFPS session. The control group had no HFPS. Both groups completed a case quiz. Confidence surveys pre- and postsimulation were completed. From October 2010 through March 2013, 55 residents who rotated through the pediatric cardiology rotation were used in the final analysis (30 control, 25 in the study group). There was no significant difference between groups on the initial cardiology quiz. The study group scored higher on the case quiz compared with the control group (P = .024). Based on pre- and postsimulation questionnaires, residents' confidence in approaching a pediatric cardiology patient improved from an average Likert score of 5.1 to 7.5 (on scale of 0-10) (P cardiology rotation was feasible and well received. Our study suggests that simulation promotes increased confidence and may modestly improve clinical reasoning compared to traditional educational techniques. Targeted simulation sessions may readily be incorporated into pediatric subspecialty rotations. © 2014 Wiley Periodicals, Inc.

  7. Improved performance of maternal-fetal medicine staff after maternal cardiac arrest simulation-based training.

    Science.gov (United States)

    Fisher, Nelli; Eisen, Lewis A; Bayya, Jyothshna V; Dulu, Alina; Bernstein, Peter S; Merkatz, Irwin R; Goffman, Dena

    2011-09-01

    To determine the impact of simulation-based maternal cardiac arrest training on performance, knowledge, and confidence among Maternal-Fetal Medicine staff. Maternal-Fetal Medicine staff (n = 19) participated in a maternal arrest simulation program. Based on evaluation of performance during initial simulations, an intervention was designed including: basic life support course, advanced cardiac life support pregnancy modification lecture, and simulation practice. Postintervention evaluative simulations were performed. All simulations included a knowledge test, confidence survey, and debriefing. A checklist with 9 pregnancy modification (maternal) and 16 critical care (25 total) tasks was used for scoring. Postintervention scores reflected statistically significant improvement. Maternal-Fetal Medicine staff demonstrated statistically significant improvement in timely initiation of cardiopulmonary resuscitation (120 vs 32 seconds, P = .042) and cesarean delivery (240 vs 159 seconds, P = .017). Prompt cardiopulmonary resuscitation initiation and pregnancy modifications application are critical in maternal and fetal survival during cardiac arrest. Simulation is a useful tool for Maternal-Fetal Medicine staff to improve skills, knowledge, and confidence in the management of this catastrophic event. Published by Mosby, Inc.

  8. Improvement of Analytical Technique for Determination of Gold in ...

    African Journals Online (AJOL)

    This article elucidates the improvement of analytical technique for determination of gold in geological matrix. Samples suspected to have gold in them were subjected to neutron flux from the Nigeria Research Reactor (NRR-1), a Miniature Neutron Source Reactor (MNSR). Two geological samples – one sample was ...

  9. Development of phased mission analysis program with Monte Carlo method. Improvement of the variance reduction technique with biasing towards top event

    International Nuclear Information System (INIS)

    Yang Jinan; Mihara, Takatsugu

    1998-12-01

    This report presents a variance reduction technique to estimate the reliability and availability of highly complex systems during phased mission time using the Monte Carlo simulation. In this study, we introduced the variance reduction technique with a concept of distance between the present system state and the cut set configurations. Using this technique, it becomes possible to bias the transition from the operating states to the failed states of components towards the closest cut set. Therefore a component failure can drive the system towards a cut set configuration more effectively. JNC developed the PHAMMON (Phased Mission Analysis Program with Monte Carlo Method) code which involved the two kinds of variance reduction techniques: (1) forced transition, and (2) failure biasing. However, these techniques did not guarantee an effective reduction in variance. For further improvement, a variance reduction technique incorporating the distance concept was introduced to the PHAMMON code and the numerical calculation was carried out for the different design cases of decay heat removal system in a large fast breeder reactor. Our results indicate that the technique addition of this incorporating distance concept is an effective means of further reducing the variance. (author)

  10. An Improved FFR Design with a Ventilation Fan: CFD Simulation and Validation.

    Science.gov (United States)

    Zhang, Xiaotie; Li, Hui; Shen, Shengnan; Rao, Yu; Chen, Feng

    2016-01-01

    This article presents an improved Filtering Facepiece Respirator (FFR) designed to increase the comfort of wearers during low-moderate work. The improved FFR aims to lower the deadspace temperature and CO2 level by an active ventilation fan. The reversing modeling is used to build the 3D geometric model of this FFR; the Computational Fluid Dynamics (CFD) simulation is then introduced to investigate the flow field. Based on the simulation result, the ventilation fan of the improved FFR can fit the flow field well when placed in the proper blowing orientation; streamlines from this fan show a cup-shape distribution and are perfectly matched to the shape of the FFR and human face when the fan blowing inward. In the deadspace of the improved FFR, the CO2 volume fraction is controlled by the optimized flow field. In addition, an experimental prototype of the improved FFR has been tested to validate the simulation. A wireless temperature sensor is used to detect the temperature variation inside the prototype FFR, deadspace temperature is lowered by 2 K compared to the normal FFR without a fan. An infrared camera (IRC) method is used to elucidate the temperature distribution on the prototype FFR's outside surface and the wearer's face, surface temperature is lowered notably. Both inside and outside temperature results from the simulation are in agreement with experimental results. Therefore, adding an inward-blowing fan on the outer surface of an N95 FFR is a feasible approach to reducing the deadspace CO2 concentration and improve temperature comfort.

  11. A Comparative Analysis of Transmission Control Protocol Improvement Techniques over Space-Based Transmission Media

    National Research Council Canada - National Science Library

    Lawson, Joseph M

    2006-01-01

    ... justification for the implementation of a given enhancement technique. The research questions were answered through model and simulation of a satellite transmission system via a Linux-based network topology...

  12. Improving a Computer Networks Course Using the Partov Simulation Engine

    Science.gov (United States)

    Momeni, B.; Kharrazi, M.

    2012-01-01

    Computer networks courses are hard to teach as there are many details in the protocols and techniques involved that are difficult to grasp. Employing programming assignments as part of the course helps students to obtain a better understanding and gain further insight into the theoretical lectures. In this paper, the Partov simulation engine and…

  13. Use of the liquisolid compact technique for improvement of the dissolution rate of valsartan

    Directory of Open Access Journals (Sweden)

    Naveen Chella

    2012-10-01

    Full Text Available The aim of this study was to improve the dissolution rate of the poorly soluble drug valsartan by delivering the drug as a liquisolid compact. Liquisolid compacts were prepared using propylene glycol as solvent, Avicel PH102 as carrier, and Aerosil 200 as the coating material. The crystallinity of the newly formulated drug and the interaction between excipients was examined by X-ray powder diffraction and Fourier-transform infrared spectroscopy, respectively. The dissolution studies for the liquisolid formulation and the marketed product were carried out at different pH values. The results showed no change in the crystallinity of the drug and no interaction between excipients. The dissolution efficiency of valsartan at 15 min was increased from 4.02% for plain drug and 13.58% for marketed product to 29.47% for the liquisolid formulation. The increase in the dissolution rate was also found to be significant compared to the marketed product at lower pH values, simulating the gastric environment where valsartan is largely absorbed. The liquisolid technique appears to be a promising approach for improving the dissolution of poorly soluble drugs like valsartan.

  14. Application of schlieren techniques for improved understanding of underground mine ventilation

    Energy Technology Data Exchange (ETDEWEB)

    Jong, E.C.; Luxbacher, K.D. [Virginia Tech, Blacksburg, VA (United States)

    2010-07-01

    Mine ventilation systems must be maintained in optimal running order in order to suppress dusts and provide fresh air to mine workers. However, it is difficult to gather representative ventilation data because of the dynamic nature of mines, including geologic conditions, equipment operations, personnel movements, advance of mine openings and atmospheric changes. Errors and imprecision in computer codes can be detrimental to mine forecasting. The best way to improve the validity of ventilation models is to increase the quality of survey data. This study examined the feasibility of using the background-oriented schlieren (BOS) flow visualization method to reach this objective. Schlieren techniques involve the use of refractive properties of different air densities to enhance the distortions of light, thereby allowing airflow to be visualized. In this study, the BOS technique was used to image flow with 2 fans, an axivane fan and a custom built axial flow fan. The results showed that the BOS technique can clearly display air flow under the correct conditions. Producing an accurate picture of air flow can improve the industry's overall understanding of air flow and resistance, thus improving mine safety and productivity. 8 refs., 7 figs.

  15. Application of schlieren techniques for improved understanding of underground mine ventilation

    International Nuclear Information System (INIS)

    Jong, E.C.; Luxbacher, K.D.

    2010-01-01

    Mine ventilation systems must be maintained in optimal running order in order to suppress dusts and provide fresh air to mine workers. However, it is difficult to gather representative ventilation data because of the dynamic nature of mines, including geologic conditions, equipment operations, personnel movements, advance of mine openings and atmospheric changes. Errors and imprecision in computer codes can be detrimental to mine forecasting. The best way to improve the validity of ventilation models is to increase the quality of survey data. This study examined the feasibility of using the background-oriented schlieren (BOS) flow visualization method to reach this objective. Schlieren techniques involve the use of refractive properties of different air densities to enhance the distortions of light, thereby allowing airflow to be visualized. In this study, the BOS technique was used to image flow with 2 fans, an axivane fan and a custom built axial flow fan. The results showed that the BOS technique can clearly display air flow under the correct conditions. Producing an accurate picture of air flow can improve the industry's overall understanding of air flow and resistance, thus improving mine safety and productivity. 8 refs., 7 figs.

  16. Improvement in QEPAS system utilizing a second harmonic based wavelength calibration technique

    Science.gov (United States)

    Zhang, Qinduan; Chang, Jun; Wang, Fupeng; Wang, Zongliang; Xie, Yulei; Gong, Weihua

    2018-05-01

    A simple laser wavelength calibration technique, based on second harmonic signal, is demonstrated in this paper to improve the performance of quartz enhanced photoacoustic spectroscopy (QEPAS) gas sensing system, e.g. improving the signal to noise ratio (SNR), detection limit and long-term stability. Constant current, corresponding to the gas absorption line, combining f/2 frequency sinusoidal signal are used to drive the laser (constant driving mode), a software based real-time wavelength calibration technique is developed to eliminate the wavelength drift due to ambient fluctuations. Compared to conventional wavelength modulation spectroscopy (WMS), this method allows lower filtering bandwidth and averaging algorithm applied to QEPAS system, improving SNR and detection limit. In addition, the real-time wavelength calibration technique guarantees the laser output is modulated steadily at gas absorption line. Water vapor is chosen as an objective gas to evaluate its performance compared to constant driving mode and conventional WMS system. The water vapor sensor was designed insensitive to the incoherent external acoustic noise by the numerical averaging technique. As a result, the SNR increases 12.87 times in wavelength calibration technique based system compared to conventional WMS system. The new system achieved a better linear response (R2 = 0 . 9995) in concentration range from 300 to 2000 ppmv, and achieved a minimum detection limit (MDL) of 630 ppbv.

  17. Numerical simulation of 3D unsteady flow in a rotating pump by dynamic mesh technique

    International Nuclear Information System (INIS)

    Huang, S; Guo, J; Yang, F X

    2013-01-01

    In this paper, the numerical simulation of unsteady flow for three kinds of typical rotating pumps, roots blower, roto-jet pump and centrifugal pump, were performed using the three-dimensional Dynamic Mesh technique. In the unsteady simulation, all the computational domains, as stationary, were set in one inertial reference frame. The motions of the solid boundaries were defined by the Profile file in FLUENT commercial code, in which the rotational orientation and speed of the rotors were specified. Three methods (Spring-based Smoothing, Dynamic Layering and Local Re-meshing) were used to achieve mesh deformation and re-meshing. The unsteady solutions of flow field and pressure distribution were solved. After a start-up stage, the flow parameters exhibit time-periodic behaviour corresponding to blade passing frequency of rotor. This work shows that Dynamic Mesh technique could achieve numerical simulation of three-dimensional unsteady flow field in various kinds of rotating pumps and have a strong versatility and broad application prospects

  18. Simulation-based Mastery Learning Improves Cardiac Auscultation Skills in Medical Students

    Science.gov (United States)

    McGaghie, William C.; Cohen, Elaine R.; Kaye, Marsha; Wayne, Diane B.

    2010-01-01

    Background Cardiac auscultation is a core clinical skill. However, prior studies show that trainee skills are often deficient and that clinical experience is not a proxy for competence. Objective To describe a mastery model of cardiac auscultation education and evaluate its effectiveness in improving bedside cardiac auscultation skills. Design Untreated control group design with pretest and posttest. Participants Third-year students who received a cardiac auscultation curriculum and fourth year students who did not. Intervention A cardiac auscultation curriculum consisting of a computer tutorial and a cardiac patient simulator. All third-year students were required to meet or exceed a minimum passing score (MPS) set by an expert panel at posttest. Measurements Diagnostic accuracy with simulated heart sounds and actual patients. Results Trained third-year students (n = 77) demonstrated significantly higher cardiac auscultation accuracy compared to untrained fourth year students (n = 31) in assessment of simulated heart sounds (93.8% vs. 73.9%, p auscultation curriculum consisting of deliberate practice with a computer-based tutorial and a cardiac patient simulator resulted in improved assessment of simulated heart sounds and more accurate examination of actual patients. PMID:20339952

  19. In situ pediatric trauma simulation: assessing the impact and feasibility of an interdisciplinary pediatric in situ trauma care quality improvement simulation program.

    Science.gov (United States)

    Auerbach, Marc; Roney, Linda; Aysseh, April; Gawel, Marcie; Koziel, Jeannette; Barre, Kimberly; Caty, Michael G; Santucci, Karen

    2014-12-01

    This study aimed to evaluate the feasibility and measure the impact of an in situ interdisciplinary pediatric trauma quality improvement simulation program. Twenty-two monthly simulations were conducted in a tertiary care pediatric emergency department with the aim of improving the quality of pediatric trauma (February 2010 to November 2012). Each session included 20 minutes of simulated patient care, followed by 30 minutes of debriefing that focused on teamwork, communication, and the identification of gaps in care. A single rater scored the performance of the team in real time using a validated assessment instrument for 6 subcomponents of care (teamwork, airway, intubation, breathing, circulation, and disability). Participants completed a survey and written feedback forms. A trend analysis of the 22 simulations found statistically significant positive trends for overall performance, teamwork, and intubation subcomponents; the strength of the upward trend was the strongest for the teamwork (τ = 0.512), followed by overall performance (τ = 0.488) and intubation (τ = 0.433). Two hundred fifty-one of 398 participants completed the participant feedback form (response rate, 63%), reporting that debriefing was the most valuable aspect of the simulation. An in situ interdisciplinary pediatric trauma simulation quality improvement program resulted in improved validated trauma simulation assessment scores for overall performance, teamwork, and intubation. Participants reported high levels of satisfaction with the program, and debriefing was reported as the most valuable component of the program.

  20. Application of parallel computing techniques to a large-scale reservoir simulation

    International Nuclear Information System (INIS)

    Zhang, Keni; Wu, Yu-Shu; Ding, Chris; Pruess, Karsten

    2001-01-01

    Even with the continual advances made in both computational algorithms and computer hardware used in reservoir modeling studies, large-scale simulation of fluid and heat flow in heterogeneous reservoirs remains a challenge. The problem commonly arises from intensive computational requirement for detailed modeling investigations of real-world reservoirs. This paper presents the application of a massive parallel-computing version of the TOUGH2 code developed for performing large-scale field simulations. As an application example, the parallelized TOUGH2 code is applied to develop a three-dimensional unsaturated-zone numerical model simulating flow of moisture, gas, and heat in the unsaturated zone of Yucca Mountain, Nevada, a potential repository for high-level radioactive waste. The modeling approach employs refined spatial discretization to represent the heterogeneous fractured tuffs of the system, using more than a million 3-D gridblocks. The problem of two-phase flow and heat transfer within the model domain leads to a total of 3,226,566 linear equations to be solved per Newton iteration. The simulation is conducted on a Cray T3E-900, a distributed-memory massively parallel computer. Simulation results indicate that the parallel computing technique, as implemented in the TOUGH2 code, is very efficient. The reliability and accuracy of the model results have been demonstrated by comparing them to those of small-scale (coarse-grid) models. These comparisons show that simulation results obtained with the refined grid provide more detailed predictions of the future flow conditions at the site, aiding in the assessment of proposed repository performance

  1. Use of natural geochemical tracers to improve reservoir simulation models

    Energy Technology Data Exchange (ETDEWEB)

    Huseby, O.; Chatzichristos, C.; Sagen, J.; Muller, J.; Kleven, R.; Bennett, B.; Larter, S.; Stubos, A.K.; Adler, P.M.

    2005-01-01

    This article introduces a methodology for integrating geochemical data in reservoir simulations to improve hydrocarbon reservoir models. The method exploits routine measurements of naturally existing inorganic ion concentration in hydrocarbon reservoir production wells, and uses the ions as non-partitioning water tracers. The methodology is demonstrated on a North Sea field case, using the field's reservoir model, together with geochemical information (SO{sub 4}{sup 2}, Mg{sup 2+} K{sup +}, Ba{sup 2+}, Sr{sup 2+}, Ca{sup 2+}, Cl{sup -} concentrations) from the field's producers. From the data-set we show that some of the ions behave almost as ideal sea-water tracers, i.e. without sorption to the matrix, ion-exchange with the matrix or scale-formation with other ions in the formation water. Moreover, the dataset shows that ion concentrations in pure formation-water vary according to formation. This information can be used to allocate produced water to specific water-producing zones in commingled production. Based on an evaluation of the applicability of the available data, one inorganic component, SO{sub 4}{sup 2}, is used as a natural seawater tracer. Introducing SO{sub 4}{sup 2} as a natural tracer in a tracer simulation has revealed a potential for improvements of the reservoir model. By tracking the injected seawater it was possible to identify underestimated fault lengths in the reservoir model. The demonstration confirms that geochemical data are valuable additional information for reservoir characterization, and shows that integration of geochemical data into reservoir simulation procedures can improve reservoir simulation models. (author)

  2. An Improved Scheduling Technique for Time-Triggered Embedded Systems

    DEFF Research Database (Denmark)

    Pop, Paul; Eles, Petru; Peng, Zebo

    1999-01-01

    clock synchronization and mode changes. We have improved the quality of the schedules by introducing a new priority function that takes into consideration the communication protocol. Communication has been optimized through packaging messages into slots with a properly selected order and lengths......In this paper we present an improved scheduling technique for the synthesis of time-triggered embedded systems. Our system model captures both the flow of data and that of control. We have considered communication of data and conditions for a time-triggered protocol implementation that supports...

  3. IMPROVING MEDICAL EDUCATION: SIMULATING CHANGES IN PATIENT ANATOMY USING DYNAMIC HAPTIC FEEDBACK

    OpenAIRE

    Yovanoff, Mary; Pepley, David; Mirkin, Katelin; Moore, Jason; Han, David; Miller, Scarlett

    2016-01-01

    Virtual simulation is an emerging field in medical education. Research suggests that simulation reduces complication rates and improves learning gains for medical residents. One benefit of simulators is their allowance for more realistic and dynamic patient anatomies. While potentially useful throughout medical education, few studies have explored the impact of dynamic haptic simulators on medical training. In light of this research void, this study was developed to examine how a Dynamic-Hapt...

  4. Path integral molecular dynamics within the grand canonical-like adaptive resolution technique: Simulation of liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Animesh, E-mail: animesh@zedat.fu-berlin.de; Delle Site, Luigi, E-mail: dellesite@fu-berlin.de [Institute for Mathematics, Freie Universität Berlin, Berlin (Germany)

    2015-09-07

    Quantum effects due to the spatial delocalization of light atoms are treated in molecular simulation via the path integral technique. Among several methods, Path Integral (PI) Molecular Dynamics (MD) is nowadays a powerful tool to investigate properties induced by spatial delocalization of atoms; however, computationally this technique is very demanding. The above mentioned limitation implies the restriction of PIMD applications to relatively small systems and short time scales. One of the possible solutions to overcome size and time limitation is to introduce PIMD algorithms into the Adaptive Resolution Simulation Scheme (AdResS). AdResS requires a relatively small region treated at path integral level and embeds it into a large molecular reservoir consisting of generic spherical coarse grained molecules. It was previously shown that the realization of the idea above, at a simple level, produced reasonable results for toy systems or simple/test systems like liquid parahydrogen. Encouraged by previous results, in this paper, we show the simulation of liquid water at room conditions where AdResS, in its latest and more accurate Grand-Canonical-like version (GC-AdResS), is merged with two of the most relevant PIMD techniques available in the literature. The comparison of our results with those reported in the literature and/or with those obtained from full PIMD simulations shows a highly satisfactory agreement.

  5. Modeling and simulation of PEM fuel cell's flow channels using CFD techniques

    International Nuclear Information System (INIS)

    Cunha, Edgar F.; Andrade, Alexandre B.; Robalinho, Eric; Bejarano, Martha L.M.; Linardi, Marcelo; Cekinski, Efraim

    2007-01-01

    Fuel cells are one of the most important devices to obtain electrical energy from hydrogen. The Proton Exchange Membrane Fuel Cell (PEMFC) consists of two important parts: the Membrane Electrode Assembly (MEA), where the reactions occur, and the flow field plates. The plates have many functions in a fuel cell: distribute reactant gases (hydrogen and air or oxygen), conduct electrical current, remove heat and water from the electrodes and make the cell robust. The cost of the bipolar plates corresponds up to 45% of the total stack costs. The Computational Fluid Dynamic (CFD) is a very useful tool to simulate hydrogen and oxygen gases flow channels, to reduce the costs of bipolar plates production and to optimize mass transport. Two types of flow channels were studied. The first type was a commercial plate by ELECTROCELL and the other was entirely projected at Programa de Celula a Combustivel (IPEN/CNEN-SP) and the experimental data were compared with modelling results. Optimum values for each set of variables were obtained and the models verification was carried out in order to show the feasibility of this technique to improve fuel cell efficiency. (author)

  6. Improved self-reliance shearing interferometric technique for collimation testing

    Science.gov (United States)

    Zhao, Mingshan; Li, Guohua; Wang, Zhaobing; Jing, Yaling; Li, Yi

    1995-06-01

    Self-reference single plate shearing interferometric technique used for collimation testing of light beams are briefly reviewed. Two improved configurations of this self-reference interferometry with an inclined screen and matched half-field interferograms are described in detail. Sensitivity of these configurations is analyzed and compared with that of the existing ones.

  7. D Digital Simulation of Minnan Temple Architecture CAISSON'S Craft Techniques

    Science.gov (United States)

    Lin, Y. C.; Wu, T. C.; Hsu, M. F.

    2013-07-01

    Caisson is one of the important representations of the Minnan (southern Fujian) temple architecture craft techniques and decorative aesthetics. The special component design and group building method present the architectural thinking and personal characteristics of great carpenters of Minnan temple architecture. In late Qing Dynasty, the appearance and style of caissons of famous temples in Taiwan apparently presented the building techniques of the great carpenters. However, as the years went by, the caisson design and craft techniques were not fully inherited, which has been a great loss of cultural assets. Accordingly, with the caisson of Fulong temple, a work by the well-known great carpenter in Tainan as an example, this study obtained the thinking principles of the original design and the design method at initial period of construction through interview records and the step of redrawing the "Tng-Ko" (traditional design, stakeout and construction tool). We obtained the 3D point cloud model of the caisson of Fulong temple using 3D laser scanning technology, and established the 3D digital model of each component of the caisson. Based on the caisson component procedure obtained from interview records, this study conducted the digital simulation of the caisson component to completely recode and present the caisson design, construction and completion procedure. This model of preserving the craft techniques for Minnan temple caisson by using digital technology makes specific contribution to the heritage of the craft techniques while providing an important reference for the digital preservation of human cultural assets.

  8. PSH Transient Simulation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-12-21

    PSH Transient Simulation Modeling presentation from the WPTO FY14 - FY16 Peer Review. Transient effects are an important consideration when designing a PSH system, yet numerical techniques for hydraulic transient analysis still need improvements for adjustable-speed (AS) reversible pump-turbine applications.

  9. Effect of Simulation Techniques and Lecture Method on Students' Academic Performance in Mafoni Day Secondary School Maiduguri, Borno State, Nigeria

    Science.gov (United States)

    Bello, Sulaiman; Ibi, Mustapha Baba; Bukar, Ibrahim Bulama

    2016-01-01

    The study examined the effect of simulation technique and lecture method on students' academic performance in Mafoni Day Secondary School, Maiduguri. The study used both simulation technique and lecture methods of teaching at the basic level of education in the teaching/learning environment. The study aimed at determining the best predictor among…

  10. Middle-Ear Microsurgery Simulation to Improve New Robotic Procedures

    Directory of Open Access Journals (Sweden)

    Guillaume Kazmitcheff

    2014-01-01

    Full Text Available Otological microsurgery is delicate and requires high dexterity in bad ergonomic conditions. To assist surgeons in these indications, a teleoperated system, called RobOtol, is developed. This robot enhances gesture accuracy and handiness and allows exploration of new procedures for middle ear surgery. To plan new procedures that exploit the capacities given by the robot, a surgical simulator is developed. The simulation reproduces with high fidelity the behavior of the anatomical structures and can also be used as a training tool for an easier control of the robot for surgeons. In the paper, we introduce the middle ear surgical simulation and then we perform virtually two challenging procedures with the robot. We show how interactive simulation can assist in analyzing the benefits of robotics in the case of complex manipulations or ergonomics studies and allow the development of innovative surgical procedures. New robot-based microsurgical procedures are investigated. The improvement offered by RobOtol is also evaluated and discussed.

  11. Model Checking Markov Chains: Techniques and Tools

    NARCIS (Netherlands)

    Zapreev, I.S.

    2008-01-01

    This dissertation deals with four important aspects of model checking Markov chains: the development of efficient model-checking tools, the improvement of model-checking algorithms, the efficiency of the state-space reduction techniques, and the development of simulation-based model-checking

  12. Innovative application of virtual display technique in virtual museum

    Science.gov (United States)

    Zhang, Jiankang

    2017-09-01

    Virtual museum refers to display and simulate the functions of real museum on the Internet in the form of 3 Dimensions virtual reality by applying interactive programs. Based on Virtual Reality Modeling Language, virtual museum building and its effective interaction with the offline museum lie in making full use of 3 Dimensions panorama technique, virtual reality technique and augmented reality technique, and innovatively taking advantages of dynamic environment modeling technique, real-time 3 Dimensions graphics generating technique, system integration technique and other key virtual reality techniques to make sure the overall design of virtual museum.3 Dimensions panorama technique, also known as panoramic photography or virtual reality, is a technique based on static images of the reality. Virtual reality technique is a kind of computer simulation system which can create and experience the interactive 3 Dimensions dynamic visual world. Augmented reality, also known as mixed reality, is a technique which simulates and mixes the information (visual, sound, taste, touch, etc.) that is difficult for human to experience in reality. These technologies make virtual museum come true. It will not only bring better experience and convenience to the public, but also be conducive to improve the influence and cultural functions of the real museum.

  13. New techniques and results for worldline simulations of lattice field theories

    Science.gov (United States)

    Giuliani, Mario; Orasch, Oliver; Gattringer, Christof

    2018-03-01

    We use the complex ø4 field at finite density as a model system for developing further techniques based on worldline formulations of lattice field theories. More specifically we: 1) Discuss new variants of the worm algorithm for updating the ø4 theory and related systems with site weights. 2) Explore the possibility of canonical simulations in the worldline formulation. 3) Study the connection of 2-particle condensation at low temperature to scattering parameters of the theory.

  14. The Generalized Multipole Technique for the Simulation of Low-Loss Electron Energy Loss Spectroscopy

    DEFF Research Database (Denmark)

    Kiewidt, Lars; Karamehmedovic, Mirza

    2018-01-01

    In this study, we demonstrate the use of a Generalized Multipole Technique (GMT) to simulate low-loss Electron Energy Loss Spectroscopy (EELS) spectra of isolated spheriodal nanoparticles. The GMT provides certain properties, such as semi-analytical description of the electromagnetic fields...

  15. Structured training on the da Vinci Skills Simulator leads to improvement in technical performance of robotic novices.

    Science.gov (United States)

    Walliczek-Dworschak, U; Mandapathil, M; Förtsch, A; Teymoortash, A; Dworschak, P; Werner, J A; Güldner, C

    2017-02-01

    The increasing use of minimally invasive techniques such as robotic-assisted devices raises the question of how to acquire robotic surgery skills. The da Vinci Skills Simulator has been demonstrated to be an effective training tool in previous reports. To date, little data are available on how to acquire proficiency through simulator training. We investigated the outcome of a structured training programme for robotic surgical skills by robotic novices. This prospective study was conducted from January to December 2013 using the da Vinci Skills Simulator. Twenty participants, all robotic novices, were enrolled in a 4-week training curriculum. After a brief introduction to the simulator system, three consecutive repetitions of five selected exercises (Match Board 1, 2, 3 and Ring and Rail 1, 2) were performed in a defined order on days 1, 8, 15 and 22. On day 22, one repetition of a previously unpractised more advanced module (Needle Targeting) was also performed. After completion of each study day, the overall performance, time to completion, economy in motion, instrument collisions, excessive instrument force, instruments out of view, master workspace range and number of drops were analysed. Comparing the first and final repetition, overall score and time needed to complete all exercises, economy of motion and instrument collisions were significantly improved in nearly all exercises. Regarding the new exercise, a positive training effect could be demonstrated. While its overall entry score was significantly higher, the time to completion and economy of motion were significantly lower than the scores on the first repetition of the previous 5 exercises. It could be shown that training on the da Vinci Skills Simulator led to an improvement in technical performance of robotic novices. With regard to a new exercise, the training had a positive effect on the technical performance. © 2016 John Wiley & Sons Ltd.

  16. Improvement of Hydrological Simulations by Applying Daily Precipitation Interpolation Schemes in Meso-Scale Catchments

    Directory of Open Access Journals (Sweden)

    Mateusz Szcześniak

    2015-02-01

    Full Text Available Ground-based precipitation data are still the dominant input type for hydrological models. Spatial variability in precipitation can be represented by spatially interpolating gauge data using various techniques. In this study, the effect of daily precipitation interpolation methods on discharge simulations using the semi-distributed SWAT (Soil and Water Assessment Tool model over a 30-year period is examined. The study was carried out in 11 meso-scale (119–3935 km2 sub-catchments lying in the Sulejów reservoir catchment in central Poland. Four methods were tested: the default SWAT method (Def based on the Nearest Neighbour technique, Thiessen Polygons (TP, Inverse Distance Weighted (IDW and Ordinary Kriging (OK. =The evaluation of methods was performed using a semi-automated calibration program SUFI-2 (Sequential Uncertainty Fitting Procedure Version 2 with two objective functions: Nash-Sutcliffe Efficiency (NSE and the adjusted R2 coefficient (bR2. The results show that: (1 the most complex OK method outperformed other methods in terms of NSE; and (2 OK, IDW, and TP outperformed Def in terms of bR2. The median difference in daily/monthly NSE between OK and Def/TP/IDW calculated across all catchments ranged between 0.05 and 0.15, while the median difference between TP/IDW/OK and Def ranged between 0.05 and 0.07. The differences between pairs of interpolation methods were, however, spatially variable and a part of this variability was attributed to catchment properties: catchments characterised by low station density and low coefficient of variation of daily flows experienced more pronounced improvement resulting from using interpolation methods. Methods providing higher precipitation estimates often resulted in a better model performance. The implication from this study is that appropriate consideration of spatial precipitation variability (often neglected by model users that can be achieved using relatively simple interpolation methods can

  17. Performance improvement of developed program by using multi-thread technique

    Directory of Open Access Journals (Sweden)

    Surasak Jabal

    2015-03-01

    Full Text Available This research presented how to use a multi-thread programming technique to improve the performance of a program written by Windows Presentation Foundation (WPF. The Computer Assisted Instruction (CAI software, named GAME24, was selected to use as a case study. This study composed of two main parts. The first part was about design and modification of the program structure upon the Object Oriented Programing (OOP approach. The second part was about coding the program using the multi-thread technique which the number of threads were based on the calculated Catalan number. The result showed that the multi-thread programming technique increased the performance of the program 44%-88% compared to the single-thread technique. In addition, it has been found that the number of cores in the CPU also increase the performance of multithreaded program proportionally.

  18. A correlation-based pulse detection technique for gamma-ray/neutron detectors

    International Nuclear Information System (INIS)

    Faisal, Muhammad; Schiffer, Randolph T.; Flaska, Marek; Pozzi, Sara A.; Wentzloff, David D.

    2011-01-01

    We present a correlation-based detection technique that significantly improves the probability of detection for low energy pulses. We propose performing a normalized cross-correlation of the incoming pulse data to a predefined pulse template, and using a threshold correlation value to trigger the detection of a pulse. This technique improves the detector sensitivity by amplifying the signal component of incoming pulse data and rejecting noise. Simulation results for various different templates are presented. Finally, the performance of the correlation-based detection technique is compared to the current state-of-the-art techniques.

  19. An improved chaos-based secure communication technique using a novel encryption function with an embedded cipher key

    Energy Technology Data Exchange (ETDEWEB)

    Zaher, Ashraf A. [Physics Department, Science College, Kuwait University, P.O. Box 5969, Safat 13060 (Kuwait)], E-mail: ashraf.zaher@ku.edu.kw

    2009-12-15

    In this paper, a secure communication technique, using a chaotic system with a single adjustable parameter and a single observable time series, is proposed. The chosen chaotic system, which is a variant of the famous Rikitake model, has a special structure for which the adjustable parameter appears in the dynamic equation of the observable time series. This particular structure is used to build a synchronization-based state observer that is decoupled from the adaptive parameter identifier. A local Lyapunov function is used to design the parameter identifier, with an adjustable convergence rate that guarantees the stability of the overall system. A two-channel transmission method is used to exemplify the suggested technique where the secret message is encoded using a nonlinear function of both the chaotic states and the adjustable parameter of the chaotic system that acts as a secret key. Simulations show that, at the receiver, the signal can be efficiently retrieved only if the secret key is known, even when both the receiver and the transmitter are in perfect synchronization. The proposed technique is demonstrated to have improved security and privacy against intruders, when compared to other techniques reported in the literature, while being simple to implement using both analog and digital hardware. In addition, the chosen chaotic system is shown to be flexible in accommodating the transmission of signals with variable bandwidths, which promotes the superiority and versatility of the suggested secure communication technique.

  20. An improved chaos-based secure communication technique using a novel encryption function with an embedded cipher key

    International Nuclear Information System (INIS)

    Zaher, Ashraf A.

    2009-01-01

    In this paper, a secure communication technique, using a chaotic system with a single adjustable parameter and a single observable time series, is proposed. The chosen chaotic system, which is a variant of the famous Rikitake model, has a special structure for which the adjustable parameter appears in the dynamic equation of the observable time series. This particular structure is used to build a synchronization-based state observer that is decoupled from the adaptive parameter identifier. A local Lyapunov function is used to design the parameter identifier, with an adjustable convergence rate that guarantees the stability of the overall system. A two-channel transmission method is used to exemplify the suggested technique where the secret message is encoded using a nonlinear function of both the chaotic states and the adjustable parameter of the chaotic system that acts as a secret key. Simulations show that, at the receiver, the signal can be efficiently retrieved only if the secret key is known, even when both the receiver and the transmitter are in perfect synchronization. The proposed technique is demonstrated to have improved security and privacy against intruders, when compared to other techniques reported in the literature, while being simple to implement using both analog and digital hardware. In addition, the chosen chaotic system is shown to be flexible in accommodating the transmission of signals with variable bandwidths, which promotes the superiority and versatility of the suggested secure communication technique.

  1. The Effect of Autogenic Training on Self-Efficacy, Anxiety, and Performance on Nursing Student Simulation.

    Science.gov (United States)

    Holland, Brian; Gosselin, Kevin; Mulcahy, Angela

    The increased anxiety experienced by nursing students during simulations can serve as a significant barrier to learning. The use of anxiety-reducing techniques such as autogenic training (AT) can mitigate the negative effects of anxiety and improve the overall learning experience. The investigators in this study sought to understand the effect of AT on student performance and self-efficacy during simulation experiences. The use of AT was an effective technique to decrease anxiety and increase performance among nursing students during nursing simulations. Reducing anxiety during simulations can improve the student learning experience.

  2. Monte Carlo simulation and gaussian broaden techniques for full energy peak of characteristic X-ray in EDXRF

    International Nuclear Information System (INIS)

    Li Zhe; Liu Min; Shi Rui; Wu Xuemei; Tuo Xianguo

    2012-01-01

    Background: Non-standard analysis (NSA) technique is one of the most important development directions of energy dispersive X-ray fluorescence (EDXRF). Purpose: This NSA technique is mainly based on Monte Carlo (MC) simulation and full energy peak broadening, which were studied preliminarily in this paper. Methods: A kind of MC model was established for Si-PIN based EDXRF setup, and the flux spectra were obtained for iron ore sample. Finally, the flux spectra were broadened by Gaussian broaden parameters calculated by a new method proposed in this paper, and the broadened spectra were compared with measured energy spectra. Results: MC method can be used to simulate EDXRF measurement, and can correct the matrix effects among elements automatically. Peak intensities can be obtained accurately by using the proposed Gaussian broaden technique. Conclusions: This study provided a key technique for EDXRF to achieve advanced NSA technology. (authors)

  3. An Improved Ghost-cell Immersed Boundary Method for Compressible Inviscid Flow Simulations

    KAUST Repository

    Chi, Cheng

    2015-05-01

    This study presents an improved ghost-cell immersed boundary approach to represent a solid body in compressible flow simulations. In contrast to the commonly used approaches, in the present work ghost cells are mirrored through the boundary described using a level-set method to farther image points, incorporating a higher-order extra/interpolation scheme for the ghost cell values. In addition, a shock sensor is in- troduced to deal with image points near the discontinuities in the flow field. Adaptive mesh refinement (AMR) is used to improve the representation of the geometry efficiently. The improved ghost-cell method is validated against five test cases: (a) double Mach reflections on a ramp, (b) supersonic flows in a wind tunnel with a forward- facing step, (c) supersonic flows over a circular cylinder, (d) smooth Prandtl-Meyer expansion flows, and (e) steady shock-induced combustion over a wedge. It is demonstrated that the improved ghost-cell method can reach the accuracy of second order in L1 norm and higher than first order in L∞ norm. Direct comparisons against the cut-cell method demonstrate that the improved ghost-cell method is almost equally accurate with better efficiency for boundary representation in high-fidelity compressible flow simulations. Implementation of the improved ghost-cell method in reacting Euler flows further validates its general applicability for compressible flow simulations.

  4. Assessment of the neighborhood environmental effects of highway improvements through micronetwork simulation

    Energy Technology Data Exchange (ETDEWEB)

    Schimpeler, C.C. (Schimpeler--Corradino Associates, Louisville, KY); Corradino, J.C.; Siria, B.S.

    1978-01-01

    New Cut Road is a major arterial highway serving South Louisville. Until recently, it was a narrow two-lane highway of rural-type design carrying up to 14,000 vehicles per day under forced flow conditions. Then construction began to widen the road from Southside Drive to Old Third Street Road, as a result of Urban Corridor Demonstration Program funding. The impacts (traffic, noise, and air pollution) on the neighborhoods surrounding this widening have been measured through micronetwork simulation techniques. Traffic will be diverted from surrounding roads (up to 20 percent) to the widened New Cut facility, thereby eliminating ''over-capacity'' conditions in these facilities, adding several years' life. Further, expeditious movement of vehicles through the New Cut Road ''area of influence'' will have a beneficial, albeit small, effect on the local air and noise environment. New Cut Road will be a highly cost-effective, low-capital-intensive improvement.

  5. Visualization and simulation techniques for surgical simulators using actual patient's data.

    Science.gov (United States)

    Radetzky, Arne; Nürnberger, Andreas

    2002-11-01

    Because of the increasing complexity of surgical interventions research in surgical simulation became more and more important over the last years. However, the simulation of tissue deformation is still a challenging problem, mainly due to the short response times that are required for real-time interaction. The demands to hard and software are even larger if not only the modeled human anatomy is used but the anatomy of actual patients. This is required if the surgical simulator should be used as training medium for expert surgeons rather than students. In this article, suitable visualization and simulation methods for surgical simulation utilizing actual patient's datasets are described. Therefore, the advantages and disadvantages of direct and indirect volume rendering for the visualization are discussed and a neuro-fuzzy system is described, which can be used for the simulation of interactive tissue deformations. The neuro-fuzzy system makes it possible to define the deformation behavior based on a linguistic description of the tissue characteristics or to learn the dynamics by using measured data of real tissue. Furthermore, a simulator for minimally-invasive neurosurgical interventions is presented that utilizes the described visualization and simulation methods. The structure of the simulator is described in detail and the results of a system evaluation by an experienced neurosurgeon--a quantitative comparison between different methods of virtual endoscopy as well as a comparison between real brain images and virtual endoscopies--are given. The evaluation proved that the simulator provides a higher realism of the visualization and simulation then other currently available simulators. Copyright 2002 Elsevier Science B.V.

  6. Crop improvement through mutation techniques in Chinese agriculture

    International Nuclear Information System (INIS)

    Wen, X.; Qu, L.

    1996-01-01

    Induced mutations for crop improvement is the most developed field in China's nuclear-agricultural sciences. It is well known that China has supported 22% of the world's population with only 7% of its cultivated land. The continued rise in population stresses the importance of increasing food production. Although developing crop varieties is efficient in increasing food production, plant breeders are approaching the outer limits of existing and useful genetic variability. As nuclear techniques provide an efficient route to inducing genetic mutations, more and more efforts have been focused on induced genetic variability. Induced mutations have become an effective way of improving cultivars and supplementing existing germplasm. Since 1981 two nationwide co-operation programs for mutation breeding, organized by the IAEA, have been carried out. 3 tabs

  7. Preoperative warm-up the key to improved resident technique: a randomized study.

    Science.gov (United States)

    Moran-Atkin, Erin; Abdalla, Gamal; Chen, Grace; Magnuson, Thomas H; Lidor, Anne O; Schweitzer, Michael A; Steele, Kimberley E

    2015-05-01

    The ACGME has required that a skills lab be incorporated into the surgical residency curriculum. While the value of warm-up is generally accepted in other areas requiring complex motor skills, there is little evidence to support the benefits of warm-up prior to performing surgery. We are conducting this study in an attempt to identify whether a warm-up period prior to operating impacts operative technique. All general surgery residents and MIS fellows were included in this IRB-approved randomized study. Participants were randomized to either warm-up or no warm-up groups. Participants randomized to the warm-up group completed a 10 min practice session in the simulation lab within 1 h of starting the case, using an FLS training box. At the conclusion of the operation, the participant was evaluated by the attending surgeon using the validated global rating scales of Reznick and Vassiliou. The attending surgeons were blinded to the use of pre-procedure warm-up. The results of the questionnaire were analyzed using student's t test with p warm-up (19) or no warm-up (21). There was a statistically significant improvement in depth perception (p = 0.02), bimanual dexterity (p = 0.01), and efficiency of movements (p = 0.03) for those randomized to warm-up. There was statistical improvement when we preformed a composite scoring of the attending evaluations for each of the Reznick (p = 0.008) and the Vassiliou (p = 0.01) global rating scales. Preoperative warm-up significantly improves depth perception, bimanual dexterity, and efficiency of movements, as well as improvement in composite scores as judged by the attending surgeon. The lack of self-perceived improvement by the residents may be a reflection of the high standards and intense self-critique that is common among surgical trainees. We believe that our findings, while preliminary, reflect that surgical performance can be enhanced through structured warm-up activities.

  8. Optimizing Availability of a Framework in Series Configuration Utilizing Markov Model and Monte Carlo Simulation Techniques

    Directory of Open Access Journals (Sweden)

    Mansoor Ahmed Siddiqui

    2017-06-01

    Full Text Available This research work is aimed at optimizing the availability of a framework comprising of two units linked together in series configuration utilizing Markov Model and Monte Carlo (MC Simulation techniques. In this article, effort has been made to develop a maintenance model that incorporates three distinct states for each unit, while taking into account their different levels of deterioration. Calculations are carried out using the proposed model for two distinct cases of corrective repair, namely perfect and imperfect repairs, with as well as without opportunistic maintenance. Initially, results are accomplished using an analytical technique i.e., Markov Model. Validation of the results achieved is later carried out with the help of MC Simulation. In addition, MC Simulation based codes also work well for the frameworks that follow non-exponential failure and repair rates, and thus overcome the limitations offered by the Markov Model.

  9. Using computer simulations to improve concept formation in chemistry

    African Journals Online (AJOL)

    The goal of this research project was to investigate whether computer simulations used as a visually-supporting teaching strategy, can improve concept formation with regard to molecules and chemical bonding, as found in water. Both the qualitative and quantitative evaluation of responses supported the positive outcome ...

  10. Improved local lattice Monte Carlo simulation for charged systems

    Science.gov (United States)

    Jiang, Jian; Wang, Zhen-Gang

    2018-03-01

    Maggs and Rossetto [Phys. Rev. Lett. 88, 196402 (2002)] proposed a local lattice Monte Carlo algorithm for simulating charged systems based on Gauss's law, which scales with the particle number N as O(N). This method includes two degrees of freedom: the configuration of the mobile charged particles and the electric field. In this work, we consider two important issues in the implementation of the method, the acceptance rate of configurational change (particle move) and the ergodicity in the phase space sampled by the electric field. We propose a simple method to improve the acceptance rate of particle moves based on the superposition principle for electric field. Furthermore, we introduce an additional updating step for the field, named "open-circuit update," to ensure that the system is fully ergodic under periodic boundary conditions. We apply this improved local Monte Carlo simulation to an electrolyte solution confined between two low dielectric plates. The results show excellent agreement with previous theoretical work.

  11. Application perspectives of simulation techniques CFD in nuclear power plants; Perspectivas de aplicacion de tecnicas de modelado CFD en plantas nucleoelectricas

    Energy Technology Data Exchange (ETDEWEB)

    Galindo G, I. F., E-mail: igalindo@iie.org.mx [Instituto de Investigaciones Electricas, Reforma No. 113, Col. Palmira, 62490 Cuernavaca, Morelos (Mexico)

    2013-10-15

    The scenarios simulation in nuclear power plants is usually carried out with system codes that are based on concentrated parameters networks. However situations exist in some components where the flow is predominantly 3-D, as they are the natural circulation, mixed and stratification phenomena. The simulation techniques of computational fluid dynamics (CFD) have the potential to simulate these flows numerically. The use of CFD simulations embraces many branches of the engineering and continues growing, however, in relation to its application with respect to the problems related with the safety in nuclear power plants, has a smaller development, although is accelerating quickly and is expected that in the future they play a more emphasized paper in the analyses. A main obstacle to be able to achieve a general acceptance of the CFD is that the simulations should have very complete validation studies, sometimes not available. In this article a general panorama of the state of the methods application CFD in nuclear power plants is presented and the problem associated to its routine application and acceptance, including the view point of the regulatory authorities. Application examples are revised in those that the CFD offers real benefits and are also presented two illustrative study cases of the application of CFD techniques. The case of a water recipient with a heat source in its interior, similar to spent fuel pool of a nuclear power plant is presented firstly; and later the case of the Boron dilution of a water volume that enters to a nuclear reactor is presented. We can conclude that the CFD technology represents a very important opportunity to improve the phenomena understanding with a strong component 3-D and to contribute in the uncertainty reduction. (Author)

  12. Applying BI Techniques To Improve Decision Making And Provide Knowledge Based Management

    Directory of Open Access Journals (Sweden)

    Alexandra Maria Ioana FLOREA

    2015-07-01

    Full Text Available The paper focuses on BI techniques and especially data mining algorithms that can support and improve the decision making process, with applications within the financial sector. We consider the data mining techniques to be more efficient and thus we applied several techniques, supervised and unsupervised learning algorithms The case study in which these algorithms have been implemented regards the activity of a banking institution, with focus on the management of lending activities.

  13. Structural investigation and simulation of acoustic properties of some tellurite glasses using artificial intelligence technique

    International Nuclear Information System (INIS)

    Gaafar, M.S.; Abdeen, Mostafa A.M.; Marzouk, S.Y.

    2011-01-01

    Research highlights: → Simulation the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). → The glass network is strengthened by enhancing the linkage of Te-O chains. The tellurite network will also come to homogenization, because of uniform distribution of Nb 5+ ions among the Te-O chains, though some of the tellurium-oxide polyhedra still link each other in edge sharing. → Excellent agreements between the measured values and the predicted values were obtained for over 50 different tellurite glass compositions. → The model we designed gives a better agreement as compared with Makishima and Machenzie model. - Abstract: The developments in the field of industry raise the need for simulating the acoustic properties of glass materials before melting raw material oxides. In this paper, we are trying to simulate the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). The artificial neural network (ANN) technique is introduced in the current study to simulate and predict important parameters such as density, longitudinal and shear ultrasonic velocities and elastic moduli (longitudinal and shear moduli). The ANN results were found to be in successful good agreement with those experimentally measured parameters. Then the presented ANN model is used to predict the acoustic properties of some new tellurite glasses. For this purpose, four glass systems xNb 2 O 5 -(1 - x)TeO 2 , 0.1PbO-xNb 2 O 5 -(0.9 - x)TeO 2 , 0.2PbO-xNb 2 O 5 -(0.8 - x)TeO 2 and 0.05Bi 2 O 3 -xNb 2 O 5 -(0.95 - x)TeO 2 were prepared using melt quenching technique. The results of ultrasonic velocities and elastic moduli showed that the addition of Nb 2 O 5 as a network modifier provides oxygen ions to change [TeO 4 ] tbps into [TeO 3 ] tps.

  14. Structural investigation and simulation of acoustic properties of some tellurite glasses using artificial intelligence technique

    Energy Technology Data Exchange (ETDEWEB)

    Gaafar, M.S., E-mail: mohamed_s_gaafar@hotmail.com [Ultrasonic Department, National Institute for Standards, Giza (Egypt); Physics Department, Faculty of Science, Majmaah University, Zulfi (Saudi Arabia); Abdeen, Mostafa A.M., E-mail: mostafa_a_m_abdeen@hotmail.com [Dept. of Eng. Math. and Physics, Faculty of Eng., Cairo University, Giza (Egypt); Marzouk, S.Y., E-mail: samir_marzouk2001@yahoo.com [Arab Academy of Science and Technology, Al-Horria, Heliopolis, Cairo (Egypt)

    2011-02-24

    Research highlights: > Simulation the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). > The glass network is strengthened by enhancing the linkage of Te-O chains. The tellurite network will also come to homogenization, because of uniform distribution of Nb{sup 5+} ions among the Te-O chains, though some of the tellurium-oxide polyhedra still link each other in edge sharing. > Excellent agreements between the measured values and the predicted values were obtained for over 50 different tellurite glass compositions. > The model we designed gives a better agreement as compared with Makishima and Machenzie model. - Abstract: The developments in the field of industry raise the need for simulating the acoustic properties of glass materials before melting raw material oxides. In this paper, we are trying to simulate the acoustic properties of some tellurite glasses using one of the artificial intelligence techniques (artificial neural network). The artificial neural network (ANN) technique is introduced in the current study to simulate and predict important parameters such as density, longitudinal and shear ultrasonic velocities and elastic moduli (longitudinal and shear moduli). The ANN results were found to be in successful good agreement with those experimentally measured parameters. Then the presented ANN model is used to predict the acoustic properties of some new tellurite glasses. For this purpose, four glass systems xNb{sub 2}O{sub 5}-(1 - x)TeO{sub 2}, 0.1PbO-xNb{sub 2}O{sub 5}-(0.9 - x)TeO{sub 2}, 0.2PbO-xNb{sub 2}O{sub 5}-(0.8 - x)TeO{sub 2} and 0.05Bi{sub 2}O{sub 3}-xNb{sub 2}O{sub 5}-(0.95 - x)TeO{sub 2} were prepared using melt quenching technique. The results of ultrasonic velocities and elastic moduli showed that the addition of Nb{sub 2}O{sub 5} as a network modifier provides oxygen ions to change [TeO{sub 4}] tbps into [TeO{sub 3}] tps.

  15. Selecting the Most Economic Project under Uncertainty Using Bootstrap Technique and Fuzzy Simulation

    Directory of Open Access Journals (Sweden)

    Kamran Shahanaghi

    2012-01-01

    Full Text Available This article, by leaving pre-determined membership function of a fuzzy set which is a basic assumption for such subject, will try to propose a hybrid technique to select the most economic project among alternative projects in fuzziness interest rates condition. In this way, net present worth (NPW would be the economic indicator. This article tries to challenge the assumption of large sample sizes availability for membership function determination and shows that some other techniques may have less accuracy. To give a robust solution, bootstrapping and fuzzy simulation is suggested and a numerical example is given and analyzed.

  16. Home visit program improves technique survival in peritoneal dialysis.

    Science.gov (United States)

    Martino, Francesca; Adıbelli, Z; Mason, G; Nayak, A; Ariyanon, W; Rettore, E; Crepaldi, Carlo; Rodighiero, Mariapia; Ronco, Claudio

    2014-01-01

    Peritoneal dialysis (PD) is a home therapy, and technique survival is related to the adherence to PD prescription at home. The presence of a home visit program could improve PD outcomes. We evaluated its effects on clinical outcome during 1 year of follow-up. This was a case-control study. The case group included all 96 patients who performed PD in our center on January 1, 2013, and who attended a home visit program; the control group included all 92 patients who performed PD on January 1, 2008. The home visit program consisted of several additional visits to reinforce patients' confidence in PD management in their own environment. Outcomes were defined as technique failure, peritonitis episode, and hospitalization. Clinical and dialysis features were evaluated for each patient. The case group was significantly older (p = 0.048), with a lower grade of autonomy (p = 0.033), but a better hemoglobin level (p = 0.02) than the control group. During the observational period, we had 11 episodes of technique failure. We found a significant reduction in the rate of technique failure in the case group (p = 0.004). Furthermore, survival analysis showed a significant extension of PD treatment in the patients supported by the home visit program (52 vs. 48.8 weeks, p = 0.018). We did not find any difference between the two groups in terms of peritonitis and hospitalization rate; however, trends toward a reduction of Gram-positive peritonitis rates as well as prevalence and duration of hospitalization related to PD problems were identified in the case group. The retrospective nature of the analysis was a limitation of this study. The home visit program improves the survival of PD patients and could reduce the rate of Gram-positive peritonitis and hospitalization. Video Journal Club "Cappuccino with Claudio Ronco" at http://www.karger.com/?doi=365168.

  17. Pyrite: A blender plugin for visualizing molecular dynamics simulations using industry-standard rendering techniques.

    Science.gov (United States)

    Rajendiran, Nivedita; Durrant, Jacob D

    2018-05-05

    Molecular dynamics (MD) simulations provide critical insights into many biological mechanisms. Programs such as VMD, Chimera, and PyMOL can produce impressive simulation visualizations, but they lack many advanced rendering algorithms common in the film and video-game industries. In contrast, the modeling program Blender includes such algorithms but cannot import MD-simulation data. MD trajectories often require many gigabytes of memory/disk space, complicating Blender import. We present Pyrite, a Blender plugin that overcomes these limitations. Pyrite allows researchers to visualize MD simulations within Blender, with full access to Blender's cutting-edge rendering techniques. We expect Pyrite-generated images to appeal to students and non-specialists alike. A copy of the plugin is available at http://durrantlab.com/pyrite/, released under the terms of the GNU General Public License Version 3. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  18. A new and efficient transient noise analysis technique for simulation of CCD image sensors or particle detectors

    International Nuclear Information System (INIS)

    Bolcato, P.; Jarron, P.; Poujois, R.

    1993-01-01

    CCD image sensors or switched capacitor circuits used for particle detectors have a certain noise level affecting the resolution of the detector. A new noise simulation technique for these devices is presented that has been implemented in the circuit simulator ELDO. The approach is particularly useful for noise simulation in analog sampling circuits. Comparison between simulations and experimental results has been made and is shown for a 1.5 μ CMOS current mode amplifier designed for high-rate particle detectors. (R.P.) 5 refs., 7 figs

  19. 3D dose imaging for arc therapy techniques by means of Fricke gel dosimetry and dedicated Monte Carlo simulations

    International Nuclear Information System (INIS)

    Valente, Mauro; Castellano, Gustavo; Sosa, Carlos

    2008-01-01

    Full text: Radiotherapy is one of the most effective techniques for tumour treatment and control. During the last years, significant developments were performed regarding both irradiation technology and techniques. However, accurate 3D dosimetric techniques are nowadays not commercially available. Due to their intrinsic characteristics, traditional dosimetric techniques like ionisation chamber, film dosimetry or TLD do not offer proper continuous 3D dose mapping. The possibility of using ferrous sulphate (Fricke) dosimeters suitably fixed to a gel matrix, along with dedicated optical analysis methods, based on light transmission measurements for 3D absorbed dose imaging in tissue-equivalent materials, has become great interest in radiotherapy. Since Gore et al. showed in 1984 that the oxidation of ferrous ions to ferric ions still happen even when fixing the ferrous sulphate solution to a gelatine matrix, important efforts have been dedicated in developing and improving real continuous 3D dosimetric systems based on Fricke solution. The purpose of this work is to investigate the capability and suitability of Fricke gel dosimetry for arc therapy irradiations. The dosimetric system is mainly composed by Fricke gel dosimeters, suitably shaped in form of thin layers and optically analysed by means of visible light transmission measurements, acquiring sample images just before and after irradiation by means of a commercial flatbed-like scanner. Image acquisition, conversion to matrices and further analysis are accomplished by means of dedicated developed software, which includes suitable algorithms for optical density differences calculation and corresponding absorbed dose conversion. Dedicated subroutines allow 3D dose imaging reconstruction from single layer information, by means of computer tomography-like algorithms. Also, dedicated Monte Carlo (PENELOPE) subroutines have been adapted in order to achieve accurate simulation of arc therapy irradiation techniques

  20. Dosimetric study of prostate brachytherapy using techniques of Monte-Carlo simulation, experimental measurements and comparison with a treatment plan

    International Nuclear Information System (INIS)

    Teles, Pedro; Barros, Silvia; Vaz, Pedro; Goncalves, Isabel; Facure, Alessandro; Rosa, Luiz da; Santos, Maira; Pereira Junior, Pedro Paulo; Zankl, Maria

    2013-01-01

    Prostate Brachytherapy is a radiotherapy technique, which consists in inserting a number of radioactive seeds (containing, usually, the following radionuclides 125 l, 241 Am or 103 Pd ) surrounding or in the vicinity of, prostate tumor tissue . The main objective of this technique is to maximize the radiation dose to the tumor and minimize it in other tissues and organs healthy, in order to reduce its morbidity. The absorbed dose distribution in the prostate, using this technique is usually non-homogeneous and time dependent. Various parameters such as the type of seed, the attenuation interactions between them, their geometrical arrangement within the prostate, the actual geometry of the seeds,and further swelling of the prostate gland after implantation greatly influence the course of absorbed dose in the prostate and surrounding areas. Quantification of these parameters is therefore extremely important for dose optimization and improvement of their plans conventional treatment, which in many cases not fully take into account. The Monte Carlo techniques allow to study these parameters quickly and effectively. In this work, we use the program MCNPX and generic voxel phantom (GOLEM) where simulated different geometric arrangements of seeds containing 125 I, Amersham Health model of type 6711 in prostates of different sizes, in order to try to quantify some of the parameters. The computational model was validated using a phantom prostate cubic RW3 type , consisting of tissue equivalent, and thermoluminescent dosimeters. Finally, to have a term of comparison with a treatment real plan it was simulate a treatment plan used in a hospital of Rio de Janeiro, with exactly the same parameters, and our computational model. The results obtained in our study seem to indicate that the parameters described above may be a source of uncertainty in the correct evaluation of the dose required for actual treatment plans. The use of Monte Carlo techniques can serve as a complementary

  1. Application of data assimilation technique for flow field simulation for Kaiga site using TAPM model

    International Nuclear Information System (INIS)

    Shrivastava, R.; Oza, R.B.; Puranik, V.D.; Hegde, M.N.; Kushwaha, H.S.

    2008-01-01

    The data assimilation techniques are becoming popular nowadays to get realistic flow field simulation for the site under consideration. The present paper describes data assimilation technique for flow field simulation for Kaiga site using the air pollution model (TAPM) developed by CSIRO, Australia. In this, the TAPM model was run for Kaiga site for a period of one month (Nov. 2004) using the analysed meteorological data supplied with the model for Central Asian (CAS) region and the model solutions were nudged with the observed wind speed and wind direction data available for the site. The model was run with 4 nested grids with grid spacing varying from 30km, 10km, 3km and 1km respectively. The models generated results with and without nudging are statistically compared with the observations. (author)

  2. Assessment of Robotic Patient Simulators for Training in Manual Physical Therapy Examination Techniques

    Science.gov (United States)

    Ishikawa, Shun; Okamoto, Shogo; Isogai, Kaoru; Akiyama, Yasuhiro; Yanagihara, Naomi; Yamada, Yoji

    2015-01-01

    Robots that simulate patients suffering from joint resistance caused by biomechanical and neural impairments are used to aid the training of physical therapists in manual examination techniques. However, there are few methods for assessing such robots. This article proposes two types of assessment measures based on typical judgments of clinicians. One of the measures involves the evaluation of how well the simulator presents different severities of a specified disease. Experienced clinicians were requested to rate the simulated symptoms in terms of severity, and the consistency of their ratings was used as a performance measure. The other measure involves the evaluation of how well the simulator presents different types of symptoms. In this case, the clinicians were requested to classify the simulated resistances in terms of symptom type, and the average ratios of their answers were used as performance measures. For both types of assessment measures, a higher index implied higher agreement among the experienced clinicians that subjectively assessed the symptoms based on typical symptom features. We applied these two assessment methods to a patient knee robot and achieved positive appraisals. The assessment measures have potential for use in comparing several patient simulators for training physical therapists, rather than as absolute indices for developing a standard. PMID:25923719

  3. Assessment of robotic patient simulators for training in manual physical therapy examination techniques.

    Directory of Open Access Journals (Sweden)

    Shun Ishikawa

    Full Text Available Robots that simulate patients suffering from joint resistance caused by biomechanical and neural impairments are used to aid the training of physical therapists in manual examination techniques. However, there are few methods for assessing such robots. This article proposes two types of assessment measures based on typical judgments of clinicians. One of the measures involves the evaluation of how well the simulator presents different severities of a specified disease. Experienced clinicians were requested to rate the simulated symptoms in terms of severity, and the consistency of their ratings was used as a performance measure. The other measure involves the evaluation of how well the simulator presents different types of symptoms. In this case, the clinicians were requested to classify the simulated resistances in terms of symptom type, and the average ratios of their answers were used as performance measures. For both types of assessment measures, a higher index implied higher agreement among the experienced clinicians that subjectively assessed the symptoms based on typical symptom features. We applied these two assessment methods to a patient knee robot and achieved positive appraisals. The assessment measures have potential for use in comparing several patient simulators for training physical therapists, rather than as absolute indices for developing a standard.

  4. Assessment of robotic patient simulators for training in manual physical therapy examination techniques.

    Science.gov (United States)

    Ishikawa, Shun; Okamoto, Shogo; Isogai, Kaoru; Akiyama, Yasuhiro; Yanagihara, Naomi; Yamada, Yoji

    2015-01-01

    Robots that simulate patients suffering from joint resistance caused by biomechanical and neural impairments are used to aid the training of physical therapists in manual examination techniques. However, there are few methods for assessing such robots. This article proposes two types of assessment measures based on typical judgments of clinicians. One of the measures involves the evaluation of how well the simulator presents different severities of a specified disease. Experienced clinicians were requested to rate the simulated symptoms in terms of severity, and the consistency of their ratings was used as a performance measure. The other measure involves the evaluation of how well the simulator presents different types of symptoms. In this case, the clinicians were requested to classify the simulated resistances in terms of symptom type, and the average ratios of their answers were used as performance measures. For both types of assessment measures, a higher index implied higher agreement among the experienced clinicians that subjectively assessed the symptoms based on typical symptom features. We applied these two assessment methods to a patient knee robot and achieved positive appraisals. The assessment measures have potential for use in comparing several patient simulators for training physical therapists, rather than as absolute indices for developing a standard.

  5. Enhancement techniques for improving 5-aminolevulinic acid delivery through the skin

    Directory of Open Access Journals (Sweden)

    Li-Wen Zhang

    2011-03-01

    Full Text Available Photodynamic therapy (PDT is a popular technique for skin cancer treatment. Protoporphyrin IX, which is a photosensitizing agent, converted enzymatically from the prodrug 5-aminolevulinic acid (ALA, is used as a photosensitizer in PDT for cancer. However, ALA penetrates with difficulty through intact skin; therefore, improving delivery systems for ALA in the skin will play an important role in ALA-PDT. Enhancement of ALA skin penetration can be achieved by physical methods, such as iontophoresis, laser, microneedles, ultrasound, and by adding chemical penetration enhancers, such as, dimethyl sulfoxide, oleic acid, and others, whereas some researches used lipophilic ALA derivatives and different vehicles to improve the transdermal delivery of ALA. This review introduces several enhancement techniques for increasing ALA permeation through the skin.

  6. The new ATLAS Fast Calorimeter Simulation

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00176100; The ATLAS collaboration

    2016-01-01

    The physics and performance studies of the ATLAS detector at the Large Hadron Collider re- quire a large number of simulated events. A GEANT4 based detailed simulation of the ATLAS calorimeter systems is highly CPU intensive and such resolution is often unnecessary. To reduce the calorimeter simulation time by a few orders of magnitude, fast simulation tools have been developed. The Fast Calorimeter Simulation (FastCaloSim) provides a parameterised simulation of the particle energy response at the calorimeter read-out cell level. In Run 1, about 13 billion events were simulated in ATLAS, out of which 50% were produced using fast simulation. For Run 2, a new parameterisation is being developed to improve the original version: it incorporates developments in geometry and physics lists during the last five years and benefits from the knowledge acquired from the Run 1 data. The algorithm uses machine learning techniques to improve the parameterisations and to optimise the amount of information to be stored in the...

  7. CT reconstruction techniques for improved accuracy of lung CT airway measurement

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, A. [Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705 (United States); Ranallo, F. N. [Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705 and Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792 (United States); Judy, P. F. [Brigham and Women’s Hospital, Boston, Massachusetts 02115 (United States); Gierada, D. S. [Department of Radiology, Washington University, St. Louis, Missouri 63110 (United States); Fain, S. B., E-mail: sfain@wisc.edu [Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705 (United States); Department of Radiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53792 (United States); Department of Biomedical Engineering,University of Wisconsin School of Engineering, Madison, Wisconsin 53706 (United States)

    2014-11-01

    Purpose: To determine the impact of constrained reconstruction techniques on quantitative CT (qCT) of the lung parenchyma and airways for low x-ray radiation dose. Methods: Measurement of small airways with qCT remains a challenge, especially for low x-ray dose protocols. Images of the COPDGene quality assurance phantom (CTP698, The Phantom Laboratory, Salem, NY) were obtained using a GE discovery CT750 HD scanner for helical scans at x-ray radiation dose-equivalents ranging from 1 to 4.12 mSv (12–100 mA s current–time product). Other parameters were 40 mm collimation, 0.984 pitch, 0.5 s rotation, and 0.625 mm thickness. The phantom was sandwiched between 7.5 cm thick water attenuating phantoms for a total length of 20 cm to better simulate the scatter conditions of patient scans. Image data sets were reconstructed using STANDARD (STD), DETAIL, BONE, and EDGE algorithms for filtered back projection (FBP), 100% adaptive statistical iterative reconstruction (ASIR), and Veo reconstructions. Reduced (half) display field of view (DFOV) was used to increase sampling across airway phantom structures. Inner diameter (ID), wall area percent (WA%), and wall thickness (WT) measurements of eight airway mimicking tubes in the phantom, including a 2.5 mm ID (42.6 WA%, 0.4 mm WT), 3 mm ID (49.0 WA%, 0.6 mm WT), and 6 mm ID (49.0 WA%, 1.2 mm WT) were performed with Airway Inspector (Surgical Planning Laboratory, Brigham and Women’s Hospital, Boston, MA) using the phase congruency edge detection method. The average of individual measures at five central slices of the phantom was taken to reduce measurement error. Results: WA% measures were greatly overestimated while IDs were underestimated for the smaller airways, especially for reconstructions at full DFOV (36 cm) using the STD kernel, due to poor sampling and spatial resolution (0.7 mm pixel size). Despite low radiation dose, the ID of the 6 mm ID airway was consistently measured accurately for all methods other than STD

  8. CT reconstruction techniques for improved accuracy of lung CT airway measurement

    International Nuclear Information System (INIS)

    Rodriguez, A.; Ranallo, F. N.; Judy, P. F.; Gierada, D. S.; Fain, S. B.

    2014-01-01

    Purpose: To determine the impact of constrained reconstruction techniques on quantitative CT (qCT) of the lung parenchyma and airways for low x-ray radiation dose. Methods: Measurement of small airways with qCT remains a challenge, especially for low x-ray dose protocols. Images of the COPDGene quality assurance phantom (CTP698, The Phantom Laboratory, Salem, NY) were obtained using a GE discovery CT750 HD scanner for helical scans at x-ray radiation dose-equivalents ranging from 1 to 4.12 mSv (12–100 mA s current–time product). Other parameters were 40 mm collimation, 0.984 pitch, 0.5 s rotation, and 0.625 mm thickness. The phantom was sandwiched between 7.5 cm thick water attenuating phantoms for a total length of 20 cm to better simulate the scatter conditions of patient scans. Image data sets were reconstructed using STANDARD (STD), DETAIL, BONE, and EDGE algorithms for filtered back projection (FBP), 100% adaptive statistical iterative reconstruction (ASIR), and Veo reconstructions. Reduced (half) display field of view (DFOV) was used to increase sampling across airway phantom structures. Inner diameter (ID), wall area percent (WA%), and wall thickness (WT) measurements of eight airway mimicking tubes in the phantom, including a 2.5 mm ID (42.6 WA%, 0.4 mm WT), 3 mm ID (49.0 WA%, 0.6 mm WT), and 6 mm ID (49.0 WA%, 1.2 mm WT) were performed with Airway Inspector (Surgical Planning Laboratory, Brigham and Women’s Hospital, Boston, MA) using the phase congruency edge detection method. The average of individual measures at five central slices of the phantom was taken to reduce measurement error. Results: WA% measures were greatly overestimated while IDs were underestimated for the smaller airways, especially for reconstructions at full DFOV (36 cm) using the STD kernel, due to poor sampling and spatial resolution (0.7 mm pixel size). Despite low radiation dose, the ID of the 6 mm ID airway was consistently measured accurately for all methods other than STD

  9. Nonlinear Multigrid for Reservoir Simulation

    DEFF Research Database (Denmark)

    Christensen, Max la Cour; Eskildsen, Klaus Langgren; Engsig-Karup, Allan Peter

    2016-01-01

    efficiency for a black-oil model. Furthermore, the use of the FAS method enables a significant reduction in memory usage compared with conventional techniques, which suggests new possibilities for improved large-scale reservoir simulation and numerical efficiency. Last, nonlinear multilevel preconditioning...

  10. First of all: Do not harm! Use of simulation for the training of regional anaesthesia techniques: Which skills can be trained without the patient as substitute for a mannequin.

    Science.gov (United States)

    Sujatta, Susanne

    2015-03-01

    Character of clinical skills training is always influenced by technical improvement and cultural changes. Over the last years, two trends have changed the way of traditional apprenticeship-style training in regional anaesthesia: firstly, the development in ultrasound-guided regional anaesthesia, and secondly, the reduced acceptance of using patients as mannequins for invasive techniques. Against this background, simulation techniques are explored, ranging from simple low-fidelity part-task training models to train skills in needle application, to highly sophisticated virtual reality models – the full range is covered. This review tries to discuss all available options with benefits and neglects. The task in clinical practice will be in choosing the right level of sophistication for the desired approach and trainee level. However, the transfer of simulated skills to clinical practice has not been evaluated. It has to be proven whether simulation-trained skills could, as a last consequence, reduce the risk to patients. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Monte Carlo molecular simulations: improving the statistical efficiency of samples with the help of artificial evolution algorithms; Simulations moleculaires de Monte Carlo: amelioration de l'efficacite statistique de l'echantillonnage grace aux algorithmes d'evolution artificielle

    Energy Technology Data Exchange (ETDEWEB)

    Leblanc, B.

    2002-03-01

    Molecular simulation aims at simulating particles in interaction, describing a physico-chemical system. When considering Markov Chain Monte Carlo sampling in this context, we often meet the same problem of statistical efficiency as with Molecular Dynamics for the simulation of complex molecules (polymers for example). The search for a correct sampling of the space of possible configurations with respect to the Boltzmann-Gibbs distribution is directly related to the statistical efficiency of such algorithms (i.e. the ability of rapidly providing uncorrelated states covering all the configuration space). We investigated how to improve this efficiency with the help of Artificial Evolution (AE). AE algorithms form a class of stochastic optimization algorithms inspired by Darwinian evolution. Efficiency measures that can be turned into efficiency criteria have been first searched before identifying parameters that could be optimized. Relative frequencies for each type of Monte Carlo moves, usually empirically chosen in reasonable ranges, were first considered. We combined parallel simulations with a 'genetic server' in order to dynamically improve the quality of the sampling during the simulations progress. Our results shows that in comparison with some reference settings, it is possible to improve the quality of samples with respect to the chosen criterion. The same algorithm has been applied to improve the Parallel Tempering technique, in order to optimize in the same time the relative frequencies of Monte Carlo moves and the relative frequencies of swapping between sub-systems simulated at different temperatures. Finally, hints for further research in order to optimize the choice of additional temperatures are given. (author)

  12. Correlation techniques for the improvement of signal-to-noise ratio in measurements with stochastic processes

    CERN Document Server

    Reddy, V R; Reddy, T G; Reddy, P Y; Reddy, K R

    2003-01-01

    An AC modulation technique is described to convert stochastic signal variations into an amplitude variation and its retrieval through Fourier analysis. It is shown that this AC detection of signals of stochastic processes when processed through auto- and cross-correlation techniques improve the signal-to-noise ratio; the correlation techniques serve a similar purpose of frequency and phase filtering as that of phase-sensitive detection. A few model calculations applied to nuclear spectroscopy measurements such as Angular Correlations, Mossbauer spectroscopy and Pulse Height Analysis reveal considerable improvement in the sensitivity of signal detection. Experimental implementation of the technique is presented in terms of amplitude variations of harmonics representing the derivatives of normal spectra. Improved detection sensitivity to spectral variations is shown to be significant. These correlation techniques are general and can be made applicable to all the fields of particle counting where measurements ar...

  13. Modeling techniques for quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Jirauschek, Christian [Institute for Nanoelectronics, Technische Universität München, D-80333 Munich (Germany); Kubis, Tillmann [Network for Computational Nanotechnology, Purdue University, 207 S Martin Jischke Drive, West Lafayette, Indiana 47907 (United States)

    2014-03-15

    Quantum cascade lasers are unipolar semiconductor lasers covering a wide range of the infrared and terahertz spectrum. Lasing action is achieved by using optical intersubband transitions between quantized states in specifically designed multiple-quantum-well heterostructures. A systematic improvement of quantum cascade lasers with respect to operating temperature, efficiency, and spectral range requires detailed modeling of the underlying physical processes in these structures. Moreover, the quantum cascade laser constitutes a versatile model device for the development and improvement of simulation techniques in nano- and optoelectronics. This review provides a comprehensive survey and discussion of the modeling techniques used for the simulation of quantum cascade lasers. The main focus is on the modeling of carrier transport in the nanostructured gain medium, while the simulation of the optical cavity is covered at a more basic level. Specifically, the transfer matrix and finite difference methods for solving the one-dimensional Schrödinger equation and Schrödinger-Poisson system are discussed, providing the quantized states in the multiple-quantum-well active region. The modeling of the optical cavity is covered with a focus on basic waveguide resonator structures. Furthermore, various carrier transport simulation methods are discussed, ranging from basic empirical approaches to advanced self-consistent techniques. The methods include empirical rate equation and related Maxwell-Bloch equation approaches, self-consistent rate equation and ensemble Monte Carlo methods, as well as quantum transport approaches, in particular the density matrix and non-equilibrium Green's function formalism. The derived scattering rates and self-energies are generally valid for n-type devices based on one-dimensional quantum confinement, such as quantum well structures.

  14. Modeling techniques for quantum cascade lasers

    Science.gov (United States)

    Jirauschek, Christian; Kubis, Tillmann

    2014-03-01

    Quantum cascade lasers are unipolar semiconductor lasers covering a wide range of the infrared and terahertz spectrum. Lasing action is achieved by using optical intersubband transitions between quantized states in specifically designed multiple-quantum-well heterostructures. A systematic improvement of quantum cascade lasers with respect to operating temperature, efficiency, and spectral range requires detailed modeling of the underlying physical processes in these structures. Moreover, the quantum cascade laser constitutes a versatile model device for the development and improvement of simulation techniques in nano- and optoelectronics. This review provides a comprehensive survey and discussion of the modeling techniques used for the simulation of quantum cascade lasers. The main focus is on the modeling of carrier transport in the nanostructured gain medium, while the simulation of the optical cavity is covered at a more basic level. Specifically, the transfer matrix and finite difference methods for solving the one-dimensional Schrödinger equation and Schrödinger-Poisson system are discussed, providing the quantized states in the multiple-quantum-well active region. The modeling of the optical cavity is covered with a focus on basic waveguide resonator structures. Furthermore, various carrier transport simulation methods are discussed, ranging from basic empirical approaches to advanced self-consistent techniques. The methods include empirical rate equation and related Maxwell-Bloch equation approaches, self-consistent rate equation and ensemble Monte Carlo methods, as well as quantum transport approaches, in particular the density matrix and non-equilibrium Green's function formalism. The derived scattering rates and self-energies are generally valid for n-type devices based on one-dimensional quantum confinement, such as quantum well structures.

  15. Establishment of an open database of realistic simulated data for evaluation of partial volume correction techniques in brain PET/MR

    Energy Technology Data Exchange (ETDEWEB)

    Mota, Ana [Instituto de Biofísica e Engenharia Biomédica, FC-UL, Lisboa (Portugal); Institute of Nuclear Medicine, UCL, London (United Kingdom); Cuplov, Vesna [Instituto de Biofísica e Engenharia Biomédica, FC-UL, Lisboa (Portugal); Schott, Jonathan; Hutton, Brian; Thielemans, Kris [Institute of Nuclear Medicine, UCL, London (United Kingdom); Drobnjak, Ivana [Centre of Medical Image Computing, UCL, London (United Kingdom); Dickson, John [Institute of Nuclear Medicine, UCL, London (United Kingdom); Bert, Julien [INSERM UMR1101, LaTIM, CHRU de Brest, Brest (France); Burgos, Ninon; Cardoso, Jorge; Modat, Marc; Ourselin, Sebastien [Centre of Medical Image Computing, UCL, London (United Kingdom); Erlandsson, Kjell [Institute of Nuclear Medicine, UCL, London (United Kingdom)

    2015-05-18

    The Partial Volume (PV) effect in Positron Emission Tomography (PET) imaging leads to loss in quantification accuracy, which manifests in PV effects (small objects occupy partially the sensitive volume of the imaging instrument, resulting in blurred images). Simultaneous acquisition of PET and Magnetic Resonance Imaging (MRI) produces concurrent metabolic and anatomical information. The latter has proved to be very helpful for the correction of PV effects. Currently, there are several techniques used for PV correction. They can be applied directly during the reconstruction process or as a post-processing step after image reconstruction. In order to evaluate the efficacy of the different PV correction techniques in brain- PET, we are constructing a database of simulated data. Here we present the framework and steps involved in constructing this database. Static 18F-FDG epilepsy and 18F-Florbetapir amyloid dementia PET/MR were selected because of their very different characteristics. The methodology followed was based on four main steps: Image pre-processing, Ground Truth (GT) generation, MRI and PET data simulation and reconstruction. All steps used Open Source software and can therefore be repeated at any centre. The framework as well as the database will be freely accessible. Tools used included GIF, FSL, POSSUM, GATE and STIR. The final data obtained after simulation, involving raw or reconstructed PET data together with corresponding MRI datasets, were close to the original patient data. Besides, there is the advantage that data can be compared with the GT. We indicate several parameters that can be improved and optimized.

  16. Establishment of an open database of realistic simulated data for evaluation of partial volume correction techniques in brain PET/MR

    International Nuclear Information System (INIS)

    Mota, Ana; Cuplov, Vesna; Schott, Jonathan; Hutton, Brian; Thielemans, Kris; Drobnjak, Ivana; Dickson, John; Bert, Julien; Burgos, Ninon; Cardoso, Jorge; Modat, Marc; Ourselin, Sebastien; Erlandsson, Kjell

    2015-01-01

    The Partial Volume (PV) effect in Positron Emission Tomography (PET) imaging leads to loss in quantification accuracy, which manifests in PV effects (small objects occupy partially the sensitive volume of the imaging instrument, resulting in blurred images). Simultaneous acquisition of PET and Magnetic Resonance Imaging (MRI) produces concurrent metabolic and anatomical information. The latter has proved to be very helpful for the correction of PV effects. Currently, there are several techniques used for PV correction. They can be applied directly during the reconstruction process or as a post-processing step after image reconstruction. In order to evaluate the efficacy of the different PV correction techniques in brain- PET, we are constructing a database of simulated data. Here we present the framework and steps involved in constructing this database. Static 18F-FDG epilepsy and 18F-Florbetapir amyloid dementia PET/MR were selected because of their very different characteristics. The methodology followed was based on four main steps: Image pre-processing, Ground Truth (GT) generation, MRI and PET data simulation and reconstruction. All steps used Open Source software and can therefore be repeated at any centre. The framework as well as the database will be freely accessible. Tools used included GIF, FSL, POSSUM, GATE and STIR. The final data obtained after simulation, involving raw or reconstructed PET data together with corresponding MRI datasets, were close to the original patient data. Besides, there is the advantage that data can be compared with the GT. We indicate several parameters that can be improved and optimized.

  17. An Efficient Simulation Method for Rare Events

    KAUST Repository

    Rached, Nadhir B.

    2015-01-07

    Estimating the probability that a sum of random variables (RVs) exceeds a given threshold is a well-known challenging problem. Closed-form expressions for the sum distribution do not generally exist, which has led to an increasing interest in simulation approaches. A crude Monte Carlo (MC) simulation is the standard technique for the estimation of this type of probability. However, this approach is computationally expensive, especially when dealing with rare events. Variance reduction techniques are alternative approaches that can improve the computational efficiency of naive MC simulations. We propose an Importance Sampling (IS) simulation technique based on the well-known hazard rate twisting approach, that presents the advantage of being asymptotically optimal for any arbitrary RVs. The wide scope of applicability of the proposed method is mainly due to our particular way of selecting the twisting parameter. It is worth observing that this interesting feature is rarely satisfied by variance reduction algorithms whose performances were only proven under some restrictive assumptions. It comes along with a good efficiency, illustrated by some selected simulation results comparing the performance of our method with that of an algorithm based on a conditional MC technique.

  18. An Efficient Simulation Method for Rare Events

    KAUST Repository

    Rached, Nadhir B.; Benkhelifa, Fatma; Kammoun, Abla; Alouini, Mohamed-Slim; Tempone, Raul

    2015-01-01

    Estimating the probability that a sum of random variables (RVs) exceeds a given threshold is a well-known challenging problem. Closed-form expressions for the sum distribution do not generally exist, which has led to an increasing interest in simulation approaches. A crude Monte Carlo (MC) simulation is the standard technique for the estimation of this type of probability. However, this approach is computationally expensive, especially when dealing with rare events. Variance reduction techniques are alternative approaches that can improve the computational efficiency of naive MC simulations. We propose an Importance Sampling (IS) simulation technique based on the well-known hazard rate twisting approach, that presents the advantage of being asymptotically optimal for any arbitrary RVs. The wide scope of applicability of the proposed method is mainly due to our particular way of selecting the twisting parameter. It is worth observing that this interesting feature is rarely satisfied by variance reduction algorithms whose performances were only proven under some restrictive assumptions. It comes along with a good efficiency, illustrated by some selected simulation results comparing the performance of our method with that of an algorithm based on a conditional MC technique.

  19. An efficiency improvement in warehouse operation using simulation analysis

    Science.gov (United States)

    Samattapapong, N.

    2017-11-01

    In general, industry requires an efficient system for warehouse operation. There are many important factors that must be considered when designing an efficient warehouse system. The most important is an effective warehouse operation system that can help transfer raw material, reduce costs and support transportation. By all these factors, researchers are interested in studying about work systems and warehouse distribution. We start by collecting the important data for storage, such as the information on products, information on size and location, information on data collection and information on production, and all this information to build simulation model in Flexsim® simulation software. The result for simulation analysis found that the conveyor belt was a bottleneck in the warehouse operation. Therefore, many scenarios to improve that problem were generated and testing through simulation analysis process. The result showed that an average queuing time was reduced from 89.8% to 48.7% and the ability in transporting the product increased from 10.2% to 50.9%. Thus, it can be stated that this is the best method for increasing efficiency in the warehouse operation.

  20. Simulation Techniques That Work.

    Science.gov (United States)

    Beland, Robert M.

    1983-01-01

    At the University of Florida, simulated experiences with disabled clients help bridge the gap between coursework and internships for recreation therapy students. Actors from the university's drama department act out the roles of handicapped persons, who are interviewed by therapy students. (PP)

  1. 3D micro-crack propagation simulation at enamel/adhesive interface using FE submodeling and element death techniques.

    Science.gov (United States)

    Liu, Heng-Liang; Lin, Chun-Li; Sun, Ming-Tsung; Chang, Yen-Hsiang

    2010-06-01

    This study investigates micro-crack propagation at the enamel/adhesive interface using finite element (FE) submodeling and element death techniques. A three-dimensional (3D) FE macro-model of the enamel/adhesive/ceramic subjected to shear bond testing was generated and analyzed. A 3D micro-model with interfacial bonding structure was constructed at the upper enamel/adhesive interface where the stress concentration was found from the macro-model results. The morphology of this interfacial bonding structure (i.e., resin tag) was assigned based on resin tag geometry and enamel rod arrangement from a scanning electron microscopy micrograph. The boundary conditions for the micro-model were determined from the macro-model results. A custom iterative code combined with the element death technique was used to calculate the micro-crack propagation. Parallel experiments were performed to validate this FE simulation. The stress concentration within the adhesive occurred mainly at the upper corner near the enamel/adhesive interface and the resin tag base. A simulated fracture path was found at the resin tag base along the enamel/adhesive interface. A morphological observation of the fracture patterns obtained from in vitro testing corresponded with the simulation results. This study shows that the FE submodeling and element death techniques could be used to simulate the 3D micro-stress pattern and the crack propagation noted at the enamel/adhesive interface.

  2. Prefabricated Vertical Drain (PVD) and Deep Cement Mixing (DCM)/Stiffened DCM (SDCM) techniques for soft ground improvement

    Science.gov (United States)

    Bergado, D. T.; Long, P. V.; Chaiyaput, S.; Balasubramaniam, A. S.

    2018-04-01

    Soft ground improvement techniques have become most practical and popular methods to increase soil strength, soil stiffness and reduce soil compressibility including the soft Bangkok clay. This paper focuses on comparative performances of prefabricated vertical drain (PVD) using surcharge, vacuum and heat preloading as well as the cement-admixed clay of Deep Cement Mixing (DCM) and Stiffened DCM (SDCM) methods. The Vacuum-PVD can increase the horizontal coefficient of consolidation, Ch, resulting in faster rate of settlement at the same magnitudes of settlement compared to Conventional PVD. Several field methods of applying vacuum preloading are also compared. Moreover, the Thermal PVD and Thermal Vacuum PVD can increase further the coefficient of horizontal consolidation, Ch, with the associated reduction of kh/ks values by reducing the drainage retardation effects in the smear zone around the PVD which resulted in faster rates of consolidation and higher magnitudes of settlements. Furthermore, the equivalent smear effect due to non-uniform consolidation is also discussed in addition to the smear due to the mechanical installation of PVDs. In addition, a new kind of reinforced deep mixing method, namely Stiffened Deep Cement Mixing (SDCM) pile is introduced to improve the flexural resistance, improve the field quality control, and prevent unexpected failures of the Deep Cement Mixing (DCM) pile. The SDCM pile consists of DCM pile reinforced with the insertion of precast reinforced concrete (RC) core. The full scale test embankment on soft clay improved by SDCM and DCM piles was also analysed. Numerical simulations using the 3D PLAXIS Foundation finite element software have been done to understand the behavior of SDCM and DCM piles. The simulation results indicated that the surface settlements decreased with increasing lengths of the RC cores, and, at lesser extent, increasing sectional areas of the RC cores in the SDCM piles. In addition, the lateral movements

  3. Extension of ERIM multispectral data processing capabilities through improved data handling techniques

    Science.gov (United States)

    Kriegler, F. J.

    1973-01-01

    The improvement and extension of the capabilities of the Environmental Research Institute of Michigan processing facility in handling multispectral data are discussed. Improvements consisted of implementing hardware modifications which permitted more rapid access to the recorded data through improved numbering and indexing of such data. In addition, techniques are discussed for handling data from sources other than the ERIM M-5 and M-7 scanner systems.

  4. Experience with the Large Eddy Simulation (LES) Technique for the Modelling of Premixed and Non-premixed Combustion

    OpenAIRE

    Malalasekera, W; Ibrahim, SS; Masri, AR; Gubba, SR; Sadasivuni, SK

    2013-01-01

    Compared to RANS based combustion modelling, the Large Eddy Simulation (LES) technique has recently emerged as a more accurate and very adaptable technique in terms of handling complex turbulent interactions in combustion modelling problems. In this paper application of LES based combustion modelling technique and the validation of models in non-premixed and premixed situations are considered. Two well defined experimental configurations where high quality data are available for validation is...

  5. Uncertainty of input data for room acoustic simulations

    DEFF Research Database (Denmark)

    Jeong, Cheol-Ho; Marbjerg, Gerd; Brunskog, Jonas

    2016-01-01

    Although many room acoustic simulation models have been well established, simulation results will never be accurate with inaccurate and uncertain input data. This study addresses inappropriateness and uncertainty of input data for room acoustic simulations. Firstly, the random incidence absorption...... and scattering coefficients are insufficient when simulating highly non-diffuse rooms. More detailed information, such as the phase and angle dependence, can greatly improve the simulation results of pressure-based geometrical and wave-based models at frequencies well below the Schroeder frequency. Phase...... summarizes potential advanced absorption measurement techniques that can improve the quality of input data for room acoustic simulations. Lastly, plenty of uncertain input data are copied from unreliable sources. Software developers and users should be careful when spreading such uncertain input data. More...

  6. Edge printability: techniques used to evaluate and improve extreme wafer edge printability

    Science.gov (United States)

    Roberts, Bill; Demmert, Cort; Jekauc, Igor; Tiffany, Jason P.

    2004-05-01

    The economics of semiconductor manufacturing have forced process engineers to develop techniques to increase wafer yield. Improvements in process controls and uniformities in all areas of the fab have reduced film thickness variations at the very edge of the wafer surface. This improved uniformity has provided the opportunity to consider decreasing edge exclusions, and now the outermost extents of the wafer must be considered in the yield model and expectations. These changes have increased the requirements on lithography to improve wafer edge printability in areas that previously were not even coated. This has taxed all software and hardware components used in defining the optical focal plane at the wafer edge. We have explored techniques to determine the capabilities of extreme wafer edge printability and the components of the systems that influence this printability. We will present current capabilities and new detection techniques and the influence that the individual hardware and software components have on edge printability. We will show effects of focus sensor designs, wafer layout, utilization of dummy edge fields, the use of non-zero overlay targets and chemical/optical edge bead optimization.

  7. Improvements in image quality with pseudo-parallel imaging in the phase-scrambling fourier transform technique

    International Nuclear Information System (INIS)

    Ito, Satoshi; Kawawa, Yasuhiro; Yamada, Yoshifumi

    2010-01-01

    The signal obtained in the phase-scrambling Fourier transform (PSFT) imaging technique can be transformed to the signal described by the Fresnel transform of the objects, in which the amplitude of the PSFT presents some kind of blurred image of the objects. Therefore, the signal can be considered to exist in the object domain as well as the Fourier domain of the object. This notable feature makes it possible to assign weights to the reconstructed images by applying a weighting function to the PSFT signal after data acquisition, and as a result, pseudo-parallel image reconstruction using these aliased image data with different weights on the images is feasible. In this study, the improvements in image quality with such pseudo-parallel imaging were examined and demonstrated. The weighting function of the PSFT signal that provides a given weight on the image is estimated using the obtained image data and is iteratively updated after sensitivity encoding (SENSE)-based image reconstruction. Simulation studies showed that reconstruction errors were dramatically reduced and that the spatial resolution was also improved in almost all image spaces. The proposed method was applied to signals synthesized from MR image data with phase variations to verify its effectiveness. It was found that the image quality was improved and that images almost entirely free of aliasing artifacts could be obtained. (author)

  8. Embryo transfer simulation improves pregnancy rates and decreases time to proficiency in Reproductive Endocrinology and Infertility fellow embryo transfers.

    Science.gov (United States)

    Heitmann, Ryan J; Hill, Micah J; Csokmay, John M; Pilgrim, Justin; DeCherney, Alan H; Deering, Shad

    2017-05-01

    To design and evaluate an ET simulator to train Reproductive Endocrinology and Infertility (REI) fellows' techniques of ET. Simulation model development and retrospective cohort analysis. Not applicable. Patients undergoing IVF. Simulation model evaluation and implementation of ET simulation training. Pregnancy rates. The REI fellow and faculty evaluation responses (n = 19/21 [90%]) of the model demonstrated realistic characteristics, with evaluators concluding the model was suitable for training in almost all evaluated areas. A total of 12 REI fellows who performed ET were analyzed: 6 before ET trainer and 6 after ET trainer. Pregnancy rates were 31% in the initial 10 ETs per fellow before simulator vs. 46% after simulator. One of six pre-ET trainer fellows (17%) had pregnancy rates ≥40% in their first 10 ETs; whereas four of six post-ET trainer fellows had pregnancy rates ≥40% in their first 10 ETs. The average number of ETs to obtain >40% pregnancy efficiency was 27 ETs before trainer vs. 15 ETs after trainer. Pregnancy rates were similar in the two groups after 20 ETs, and collective terminal pregnancy rates were >50% after 40 ETs. Embryo transfer simulation improved REI fellow pregnancy rates in their first 10 transfers and led to a more rapid ET proficiency. These data suggest potential value in adopting ET simulation, even in programs with a robust history of live ET in fellowship training. Published by Elsevier Inc.

  9. Simulation and Shoulder Dystocia.

    Science.gov (United States)

    Shaddeau, Angela K; Deering, Shad

    2016-12-01

    Shoulder dystocia is an unpredictable obstetric emergency that requires prompt interventions to ensure optimal outcomes. Proper technique is important but difficult to train given the urgent and critical clinical situation. Simulation training for shoulder dystocia allows providers at all levels to practice technical and teamwork skills in a no-risk environment. Programs utilizing simulation training for this emergency have consistently demonstrated improved performance both during practice drills and in actual patients with significantly decreased risks of fetal injury. Given the evidence, simulation training for shoulder dystocia should be conducted at all institutions that provide delivery services.

  10. Somatic Embryogenesis: Still a Relevant Technique in Citrus Improvement.

    Science.gov (United States)

    Omar, Ahmad A; Dutt, Manjul; Gmitter, Frederick G; Grosser, Jude W

    2016-01-01

    The genus Citrus contains numerous fresh and processed fruit cultivars that are economically important worldwide. New cultivars are needed to battle industry threatening diseases and to create new marketing opportunities. Citrus improvement by conventional methods alone has many limitations that can be overcome by applications of emerging biotechnologies, generally requiring cell to plant regeneration. Many citrus genotypes are amenable to somatic embryogenesis, which became a key regeneration pathway in many experimental approaches to cultivar improvement. This chapter provides a brief history of plant somatic embryogenesis with focus on citrus, followed by a discussion of proven applications in biotechnology-facilitated citrus improvement techniques, such as somatic hybridization, somatic cybridization, genetic transformation, and the exploitation of somaclonal variation. Finally, two important new protocols that feature plant regeneration via somatic embryogenesis are provided: protoplast transformation and Agrobacterium-mediated transformation of embryogenic cell suspension cultures.

  11. Development of technique to apply induction heating stress improvement to recirculation inlet nozzle

    International Nuclear Information System (INIS)

    Chiba, Kunihiko; Nihei, Kenichi; Ootaka, Minoru

    2009-01-01

    Stress corrosion cracking (SCC) have been found in the primary loop recirculation (PLR) systems of boiling water reactors (BWR). Residual stress in welding heat-affected zone is one of the factors of SCC, and the residual stress improvement is one of the most effective methods to prevent SCC. Induction heating stress improvement (IHSI) is one of the techniques to improve reduce residual stress. However, it is difficult to apply IHSI to the place such as the recirculation inlet nozzle where the flow stagnates. In this present study, the technique to apply IHSI to the recirculation inlet nozzle was developed using water jet which blowed into the crevice between the nozzle safe end and the thermal sleeve. (author)

  12. Performance of medical residents in sterile techniques during central vein catheterization: randomized trial of efficacy of simulation-based training.

    Science.gov (United States)

    Khouli, Hassan; Jahnes, Katherine; Shapiro, Janet; Rose, Keith; Mathew, Joseph; Gohil, Amit; Han, Qifa; Sotelo, Andre; Jones, James; Aqeel, Adnan; Eden, Edward; Fried, Ethan

    2011-01-01

    Catheter-related bloodstream infection (CRBSI) is a preventable cause of a potentially lethal ICU infection. The optimal method to teach health-care providers correct sterile techniques during central vein catheterization (CVC) remains unclear. We randomly assigned second- and third-year internal medicine residents trained by a traditional apprenticeship model to simulation-based plus video training or video training alone from December 2007 to January 2008, with a follow-up period to examine CRBSI ending in July 2009. During the follow-up period, a simulation-based training program in sterile techniques during CVC was implemented in the medical ICU (MICU). A surgical ICU (SICU) where no residents received study interventions was used for comparison. The primary outcome measures were median residents' scores in sterile techniques and rates of CRBSI per 1,000 catheter-days. Of the 47 enrolled residents, 24 were randomly assigned to the simulation-based plus video training group and 23 to the video training group. Median baseline scores in both groups were equally poor: 12.5 to 13 (52%-54%) out of maximum score of 24 (P = .95; median difference, 0; 95% CI, 0.2-2.0). After training, median score was significantly higher for the simulation-based plus video training group: 22 (92%) vs 18 (75%) for the video training group (P training in sterile techniques during CVC is superior to traditional training or video training alone and is associated with decreased rate of CRBSI. Simulation-based training in CVC should be routinely used to reduce iatrogenic risk. ClinicalTrials.gov; No.: NCT00612131; URL: clinicaltrials.gov.

  13. A research on applications of qualitative reasoning techniques in Human Acts Simulation Program

    International Nuclear Information System (INIS)

    Far, B.H.

    1992-04-01

    Human Acts Simulation Program (HASP) is a ten-year research project of the Computing and Information Systems Center of JAERI. In HASP the goal is developing programs for an advanced intelligent robot to accomplish multiple instructions (for instance, related to surveillance, inspection and maintenance) in nuclear power plants. Some recent artificial intelligence techniques can contribute to this project. This report introduces some original contributions concerning application of Qualitative Reasoning (QR) techniques in HASP. The focus is on the knowledge-intensive tasks, including model-based reasoning, analytic learning, fault diagnosis and functional reasoning. The multi-level extended qualitative modeling for the Skill-Rule-Knowledge (S-R-K) based reasoning, that included the coordination and timing of events, Qualitative Sensitivity analysis (Q S A), Subjective Qualitative Fault Diagnosis (S Q F D) and Qualitative Function Formation (Q F F ) techniques are introduced. (author) 123 refs

  14. Fast shower simulation in the ATLAS calorimeter

    International Nuclear Information System (INIS)

    Barberio, E; Boudreau, J; Mueller, J; Tsulaia, V; Butler, B; Young, C C; Cheung, S L; Savard, P; Dell'Acqua, A; Simone, A D; Gallas, M V; Ehrenfeld, W; Glazov, A; Placakyte, R; Marshall, Z; Rimoldi, A; Waugh, A

    2008-01-01

    The time to simulate pp collisions in the ATLAS detector is largely dominated by the showering of electromagnetic particles in the heavy parts of the detector, especially the electromagnetic barrel and endcap calorimeters. Two procedures have been developed to accelerate the processing time of electromagnetic particles in these regions: (1) a fast shower parameterisation and (2) a frozen shower library. Both work by generating the response of the calorimeter to electrons and positrons with Geant 4, and then reintroduce the response into the simulation at runtime. In the fast shower parameterisation technique, a parameterisation is tuned to single electrons and used later by simulation. In the frozen shower technique, actual showers from low-energy particles are used in the simulation. Full Geant 4 simulation is used to develop showers down to ∼ 1GeV, at which point the shower is terminated by substituting a frozen shower. Judicious use of both techniques over the entire electromagnetic portion of the ATLAS calorimeter produces an important improvement of CPU time. We discuss the algorithms and their performance in this paper

  15. The relationship of superficial cerebral veins with meningiomas by simulation craniotomy technique

    International Nuclear Information System (INIS)

    Zhao Hongwei; Gong Xiangyang

    2012-01-01

    Objective: To assess the value of simulation craniotomy (SC) technique in evaluation of superficial cerebral veins (SCVs) and its relationship with convexity, parasagittal and falcine meningiomas. Methods: Forty-nine consecutive patients with convexity,parasagittal, and falcine meningiomas performed SC technique and three-dimensional contrast enhanced MR venography (3D CE MRV) in a prospective study. The number of SCVs (diameter > 1 mm) within 2 cm around the margin of tumors detected by two techniques were compared with the paired t test. Furthermore, 49 cases were divided into groups according to the tumor largest diameter, position, and dural enhancement. The image quality of SC technique in different groups were analyzed by Wilcoxon test in order to find influence factors. Results: The number of SCVs within 2 cm around the margin of tumor in SC was 4.4 ± 1.9, which was significantly less than that on 3D CE MRV (5.1 ± 2.7) (t=3.131, P<0.05). The relationship between meningiomas and the SCVs was demonstrated well on SC in majority of cases with the score of image quality was 2.5 ±0.7. The score of image quality of 12 patients with obvious dural enhancement was 1.5 ± 0.5, which was significantly lower than that of 37 patients without dural enhancement (2.8 ± 0.3) (Z=-3.093, P<0.05). The score of image quality of 18 patients with tumor larger than 4 cm in diameter (2.2 ± 0.9)was significantly lowed than that of 31 patients with small tumors (2.7 ± 0.5) (Z=-2.057, P<0.05). The score of image quality of convexity group (n=10) and parasagittal and falcine group (n=39) was 2.2 ± 0.9 and 2.6 ± 0.6,and there was no significant difference between different location group (Z=-0.604, P>0.05). Conclusions: Simulation craniotomy can exactly display SCVs avoiding the influence of deep cerebral veins and skull veins. This simple technique can provide useful information about the SCVs and their relationships with cortical structures and tumors for preoperative surgical

  16. Multilevel techniques lead to accurate numerical upscaling and scalable robust solvers for reservoir simulation

    DEFF Research Database (Denmark)

    Christensen, Max la Cour; Villa, Umberto; Vassilevski, Panayot

    2015-01-01

    approach is well suited for the solution of large problems coming from finite element discretizations of systems of partial differential equations. The AMGe technique from 10,9 allows for the construction of operator-dependent coarse (upscaled) models and guarantees approximation properties of the coarse...... implementation of the reservoir simulator is demonstrated....

  17. Assimilation of Ocean-Color Plankton Functional Types to Improve Marine Ecosystem Simulations

    Science.gov (United States)

    Ciavatta, S.; Brewin, R. J. W.; Skákala, J.; Polimene, L.; de Mora, L.; Artioli, Y.; Allen, J. I.

    2018-02-01

    We assimilated phytoplankton functional types (PFTs) derived from ocean color into a marine ecosystem model, to improve the simulation of biogeochemical indicators and emerging properties in a shelf sea. Error-characterized chlorophyll concentrations of four PFTs (diatoms, dinoflagellates, nanoplankton, and picoplankton), as well as total chlorophyll for comparison, were assimilated into a physical-biogeochemical model of the North East Atlantic, applying a localized Ensemble Kalman filter. The reanalysis simulations spanned the years 1998-2003. The skill of the reference and reanalysis simulations in estimating ocean color and in situ biogeochemical data were compared by using robust statistics. The reanalysis outperformed both the reference and the assimilation of total chlorophyll in estimating the ocean-color PFTs (except nanoplankton), as well as the not-assimilated total chlorophyll, leading the model to simulate better the plankton community structure. Crucially, the reanalysis improved the estimates of not-assimilated in situ data of PFTs, as well as of phosphate and pCO2, impacting the simulation of the air-sea carbon flux. However, the reanalysis increased further the model overestimation of nitrate, in spite of increases in plankton nitrate uptake. The method proposed here is easily adaptable for use with other ecosystem models that simulate PFTs, for, e.g., reanalysis of carbon fluxes in the global ocean and for operational forecasts of biogeochemical indicators in shelf-sea ecosystems.

  18. Filament winding technique, experiment and simulation analysis on tubular structure

    Science.gov (United States)

    Quanjin, Ma; Rejab, M. R. M.; Kaige, Jiang; Idris, M. S.; Harith, M. N.

    2018-04-01

    Filament winding process has emerged as one of the potential composite fabrication processes with lower costs. Filament wound products involve classic axisymmetric parts (pipes, rings, driveshafts, high-pressure vessels and storage tanks), non-axisymmetric parts (prismatic nonround sections and pipe fittings). Based on the 3-axis filament winding machine has been designed with the inexpensive control system, it is completely necessary to make a relative comparison between experiment and simulation on tubular structure. In this technical paper, the aim of this paper is to perform a dry winding experiment using the 3-axis filament winding machine and simulate winding process on the tubular structure using CADWIND software with 30°, 45°, 60° winding angle. The main result indicates that the 3-axis filament winding machine can produce tubular structure with high winding pattern performance with different winding angle. This developed 3-axis winding machine still has weakness compared to CAWIND software simulation results with high axes winding machine about winding pattern, turnaround impact, process error, thickness, friction impact etc. In conclusion, the 3-axis filament winding machine improvements and recommendations come up with its comparison results, which can intuitively understand its limitations and characteristics.

  19. Repeated scenario simulation to improve competency in critical care: a new approach for nursing education.

    Science.gov (United States)

    Abe, Yukie; Kawahara, Chikako; Yamashina, Akira; Tsuboi, Ryoji

    2013-01-01

    In Japan, nursing education is being reformed to improve nurses' competency. Interest in use of simulation-based education to increase nurses' competency is increasing. To examine the effectiveness of simulation-based education in improving competency of cardiovascular critical care nurses. A training program that consisted of lectures, training in cardiovascular procedures, and scenario simulations was conducted with 24 Japanese nurses working at a university hospital. Participants were allocated to 4 groups, each of which visited 4 zones and underwent scenario simulations that included debriefings during and after the simulations. In each zone, the scenario simulation was repeated and participants assessed their own technical skills by scoring their performance on a rubric. Before and after the simulations, participants also completed a survey that used the Teamwork Activity Inventory in Nursing Scale (TAINS) to assess their nontechnical skills. All the groups showed increased rubric scores after the second simulation compared with the rubric scores obtained after the first simulation, despite differences in the order in which the scenarios were presented. Furthermore, the survey revealed significant increases in scores on the teamwork scale for the following subscale items: "Attitudes of the superior" (P Job satisfaction" (P = .01), and "Confidence as a team member" (P = .004). Our new educational approach of using repeated scenario simulations and TAINS seemed not only to enhance individual nurses' technical skills in critical care nursing but also to improve their nontechnical skills somewhat.

  20. Improving Paramedic Distance Education through Mobile Mixed Reality Simulation

    Science.gov (United States)

    Birt, James; Moore, Emma; Cowling, Michael

    2017-01-01

    There is growing evidence that the use of simulation in teaching is a key means of improving learning, skills, and outcomes, particularly for practical skills. In the health sciences, the use of high-fidelity task trainers has been shown to be ideal for reducing cognitive load and leading to enhanced learning outcomes. However, how do we make…

  1. Electrical Storm Simulation to Improve the Learning Physics Process

    Science.gov (United States)

    Martínez Muñoz, Miriam; Jiménez Rodríguez, María Lourdes; Gutiérrez de Mesa, José Antonio

    2013-01-01

    This work is part of a research project whose main objective is to understand the impact that the use of Information and Communication Technology (ICT) has on the teaching and learning process on the subject of Physics. We will show that, with the use of a storm simulator, physics students improve their learning process on one hand they understand…

  2. Improving MJO Prediction and Simulation Using AGCM Coupled Ocean Model with Refined Vertical Resolution

    Science.gov (United States)

    Tu, Chia-Ying; Tseng, Wan-Ling; Kuo, Pei-Hsuan; Lan, Yung-Yao; Tsuang, Ben-Jei; Hsu, Huang-Hsiung

    2017-04-01

    Precipitation in Taiwan area is significantly influenced by MJO (Madden-Julian Oscillation) in the boreal winter. This study is therefore conducted by toggling the MJO prediction and simulation with a unique model structure. The one-dimensional TKE (Turbulence Kinetic Energy) type ocean model SIT (Snow, Ice, Thermocline) with refined vertical resolution near surface is able to resolve cool skin, as well as diurnal warm layer. SIT can simulate accurate SST and hence give precise air-sea interaction. By coupling SIT with ECHAM5 (MPI-Meteorology), CAM5 (NCAR) and HiRAM (GFDL), the MJO simulations in 20-yrs climate integrations conducted by three SIT-coupled AGCMs are significant improved comparing to those driven by prescribed SST. The horizontal resolutions in ECHAM5, CAM5 and HiRAM are 2-deg., 1-deg and 0.5-deg., respectively. This suggests that the improvement of MJO simulation by coupling SIT is AGCM-resolution independent. This study further utilizes HiRAM coupled SIT to evaluate its MJO forecast skill. HiRAM has been recognized as one of the best model for seasonal forecasts of hurricane/typhoon activity (Zhao et al., 2009; Chen & Lin, 2011; 2013), but was not as successful in MJO forecast. The preliminary result of the HiRAM-SIT experiment during DYNAMO period shows improved success in MJO forecast. These improvements of MJO prediction and simulation in both hindcast experiments and climate integrations are mainly from better-simulated SST diurnal cycle and diurnal amplitude, which is contributed by the refined vertical resolution near ocean surface in SIT. Keywords: MJO Predictability, DYNAMO

  3. Integration of an iterative methodology for exergoeconomic improvement of thermal systems with a process simulator

    International Nuclear Information System (INIS)

    Vieira, Leonardo S.; Donatelli, Joao L.; Cruz, Manuel E.

    2004-01-01

    In this paper, we present the development and automated implementation of an iterative methodology for exergoeconomic improvement of thermal systems integrated with a process simulator, so as to be applicable to real, complex plants. The methodology combines recent available exergoeconomic techniques with new qualitative and quantitative criteria for the following tasks: (i) identification of decision variables that affect system total cost and exergetic efficiency; (ii) hierarchical classification of components; (iii) identification of predominant terms in the component total cost; and (iv) choice of main decision variables in the iterative process. To show the strengths and potential advantages of the proposed methodology, it is here applied to the benchmark CGAM cogeneration system. The results obtained are presented and discussed in detail and are compared to those reached using a mathematical optimization procedure

  4. A simulation-based training program improves emergency department staff communication.

    Science.gov (United States)

    Sweeney, Lynn A; Warren, Otis; Gardner, Liz; Rojek, Adam; Lindquist, David G

    2014-01-01

    The objectives of this study were to evaluate the effectiveness of Project CLEAR!, a novel simulation-based training program designed to instill Crew Resource Management (CRM) as the communication standard and to create a service-focused environment in the emergency department (ED) by standardizing the patient encounter. A survey-based study compared physicians' and nurses' perceptions of the quality of communication before and after the training program. Surveys were developed to measure ED staff perceptions of the quality of communication between staff members and with patients. Pretraining and posttraining survey results were compared. After the training program, survey scores improved significantly on questions that asked participants to rate the overall communication between staff members and between staff and patients. A simulation-based training program focusing on CRM and standardizing the patient encounter improves communication in the ED, both between staff members and between staff members and patients.

  5. 3D DIGITAL SIMULATION OF MINNAN TEMPLE ARCHITECTURE CAISSON'S CRAFT TECHNIQUES

    Directory of Open Access Journals (Sweden)

    Y. C. Lin

    2013-07-01

    Full Text Available Caisson is one of the important representations of the Minnan (southern Fujian temple architecture craft techniques and decorative aesthetics. The special component design and group building method present the architectural thinking and personal characteristics of great carpenters of Minnan temple architecture. In late Qing Dynasty, the appearance and style of caissons of famous temples in Taiwan apparently presented the building techniques of the great carpenters. However, as the years went by, the caisson design and craft techniques were not fully inherited, which has been a great loss of cultural assets. Accordingly, with the caisson of Fulong temple, a work by the well-known great carpenter in Tainan as an example, this study obtained the thinking principles of the original design and the design method at initial period of construction through interview records and the step of redrawing the "Tng-Ko" (traditional design, stakeout and construction tool. We obtained the 3D point cloud model of the caisson of Fulong temple using 3D laser scanning technology, and established the 3D digital model of each component of the caisson. Based on the caisson component procedure obtained from interview records, this study conducted the digital simulation of the caisson component to completely recode and present the caisson design, construction and completion procedure. This model of preserving the craft techniques for Minnan temple caisson by using digital technology makes specific contribution to the heritage of the craft techniques while providing an important reference for the digital preservation of human cultural assets.

  6. Simulation-based education with mastery learning improves residents' lumbar puncture skills

    Science.gov (United States)

    Cohen, Elaine R.; Caprio, Timothy; McGaghie, William C.; Simuni, Tanya; Wayne, Diane B.

    2012-01-01

    Objective: To evaluate the effect of simulation-based mastery learning (SBML) on internal medicine residents' lumbar puncture (LP) skills, assess neurology residents' acquired LP skills from traditional clinical education, and compare the results of SBML to traditional clinical education. Methods: This study was a pretest-posttest design with a comparison group. Fifty-eight postgraduate year (PGY) 1 internal medicine residents received an SBML intervention in LP. Residents completed a baseline skill assessment (pretest) using a 21-item LP checklist. After a 3-hour session featuring deliberate practice and feedback, residents completed a posttest and were expected to meet or exceed a minimum passing score (MPS) set by an expert panel. Simulator-trained residents' pretest and posttest scores were compared to assess the impact of the intervention. Thirty-six PGY2, 3, and 4 neurology residents from 3 medical centers completed the same simulated LP assessment without SBML. SBML posttest scores were compared to neurology residents' baseline scores. Results: PGY1 internal medicine residents improved from a mean of 46.3% to 95.7% after SBML (p < 0.001) and all met the MPS at final posttest. The performance of traditionally trained neurology residents was significantly lower than simulator-trained residents (mean 65.4%, p < 0.001) and only 6% met the MPS. Conclusions: Residents who completed SBML showed significant improvement in LP procedural skills. Few neurology residents were competent to perform a simulated LP despite clinical experience with the procedure. PMID:22675080

  7. Simulating the x-ray image contrast to setup techniques with desired flaw detectability

    Science.gov (United States)

    Koshti, Ajay M.

    2015-04-01

    The paper provides simulation data of previous work by the author in developing a model for estimating detectability of crack-like flaws in radiography. The methodology is developed to help in implementation of NASA Special x-ray radiography qualification, but is generically applicable to radiography. The paper describes a method for characterizing the detector resolution. Applicability of ASTM E 2737 resolution requirements to the model are also discussed. The paper describes a model for simulating the detector resolution. A computer calculator application, discussed here, also performs predicted contrast and signal-to-noise ratio calculations. Results of various simulation runs in calculating x-ray flaw size parameter and image contrast for varying input parameters such as crack depth, crack width, part thickness, x-ray angle, part-to-detector distance, part-to-source distance, source sizes, and detector sensitivity and resolution are given as 3D surfaces. These results demonstrate effect of the input parameters on the flaw size parameter and the simulated image contrast of the crack. These simulations demonstrate utility of the flaw size parameter model in setting up x-ray techniques that provide desired flaw detectability in radiography. The method is applicable to film radiography, computed radiography, and digital radiography.

  8. Dual-energy mammography: simulation studies

    International Nuclear Information System (INIS)

    Bliznakova, K; Kolitsi, Z; Pallikarakis, N

    2006-01-01

    This paper presents a mammography simulator and demonstrates its applicability in feasibility studies in dual-energy (DE) subtraction mammography. This mammography simulator is an evolution of a previously presented x-ray imaging simulation system, which has been extended with new functionalities that are specific for DE simulations. The new features include incident exposure and dose calculations, the implementation of a DE subtraction algorithm as well as amendments to the detector and source modelling. The system was then verified by simulating experiments and comparing their results against published data. The simulator was used to carry out a feasibility study of the applicability of DE techniques in mammography, and more precisely to examine whether this modality could result in better visualization and detection of microcalcifications. Investigations were carried out using a 3D breast software phantom of average thickness, monoenergetic and polyenergetic beam spectra and various detector configurations. Dual-shot techniques were simulated. Results showed the advantage of using monoenergetic in comparison with polyenergetic beams. Optimization studies with monochromatic sources were carried out to obtain the optimal low and high incident energies, based on the assessment of the figure of merit of the simulated microcalcifications in the subtracted images. The results of the simulation study with the optimal energies demonstrated that the use of the DE technique can improve visualization and increase detectability, allowing identification of microcalcifications of sizes as small as 200 μm. The quantitative results are also verified by means of a visual inspection of the synthetic images

  9. Improvement of technique of a jerk of the qualified sportswomen in weightlifting

    Directory of Open Access Journals (Sweden)

    Oksana Solodka

    2016-12-01

    Full Text Available Purpose: the improvement of technical preparedness of the qualified female weight-lifters taking into account the group model characteristics of technique of a jerk. Material & Methods: analysis and synthesis of data of scientific and methodical literature, pedagogical experiment, method of mathematical statistics. Results: the revealed shortcomings of technique of the execution of a jerk of the qualified female weight-lifters were, considering the group model characteristics of technique of a jerk of the first group of weight categories. Complexes of compensatory exercises were offered for the purpose of correction. Conclusions: the performance of complexes of the compensatory exercises, which are directed to the improvement of competitive exercise of a jerk of bar, allowed to increase the number of successfully executed raising of bar, for 10,3–19,8%, according to initial indicators of number of rises, and also to receive positive shifts in motive structure of a jerk of bar.

  10. To improve training methods in an engine room simulator-based training

    OpenAIRE

    Lin, Chingshin

    2016-01-01

    The simulator based training are used widely in both industry and school education to reduce the accidents nowadays. This study aims to suggest the improved training methods to increase the effectiveness of engine room simulator training. The effectiveness of training in engine room will be performance indicators and the self-evaluation by participants. In the first phase of observation, the aim is to find out the possible shortcomings of current training methods based on train...

  11. Advanced modeling in positron emission tomography using Monte Carlo simulations for improving reconstruction and quantification

    International Nuclear Information System (INIS)

    Stute, Simon

    2010-01-01

    Positron Emission Tomography (PET) is a medical imaging technique that plays a major role in oncology, especially using "1"8F-Fluoro-Deoxyglucose. However, PET images suffer from a modest spatial resolution and from high noise. As a result, there is still no consensus on how tumor metabolically active volume and tumor uptake should be characterized. In the meantime, research groups keep producing new methods for such characterizations that need to be assessed. A Monte Carlo simulation based method has been developed to produce simulated PET images of patients suffering from cancer, indistinguishable from clinical images, and for which all parameters are known. The method uses high resolution PET images from patient acquisitions, from which the physiological heterogeneous activity distribution can be modeled. It was shown that the performance of quantification methods on such highly realistic simulated images are significantly lower and more variable than using simple phantom studies. Fourteen different quantification methods were also compared in realistic conditions using a group of such simulated patients. In addition, the proposed method was extended to simulate serial PET scans in the context of patient monitoring, including a modeling of the tumor changes, as well as the variability over time of non-tumoral physiological activity distribution. Monte Carlo simulations were also used to study the detection probability inside the crystals of the tomograph. A model of the crystal response was derived and included in the system matrix involved in tomographic reconstruction. The resulting reconstruction method was compared with other sophisticated methods for modeling the detector response in the image space, proposed in the literature. We demonstrated the superiority of the proposed method over equivalent approaches on simulated data, and illustrated its robustness on clinical data. For a same noise level, it is possible to reconstruct PET images offering a

  12. Improving human object recognition performance using video enhancement techniques

    Science.gov (United States)

    Whitman, Lucy S.; Lewis, Colin; Oakley, John P.

    2004-12-01

    Atmospheric scattering causes significant degradation in the quality of video images, particularly when imaging over long distances. The principle problem is the reduction in contrast due to scattered light. It is known that when the scattering particles are not too large compared with the imaging wavelength (i.e. Mie scattering) then high spatial resolution information may be contained within a low-contrast image. Unfortunately this information is not easily perceived by a human observer, particularly when using a standard video monitor. A secondary problem is the difficulty of achieving a sharp focus since automatic focus techniques tend to fail in such conditions. Recently several commercial colour video processing systems have become available. These systems use various techniques to improve image quality in low contrast conditions whilst retaining colour content. These systems produce improvements in subjective image quality in some situations, particularly in conditions of haze and light fog. There is also some evidence that video enhancement leads to improved ATR performance when used as a pre-processing stage. Psychological literature indicates that low contrast levels generally lead to a reduction in the performance of human observers in carrying out simple visual tasks. The aim of this paper is to present the results of an empirical study on object recognition in adverse viewing conditions. The chosen visual task was vehicle number plate recognition at long ranges (500 m and beyond). Two different commercial video enhancement systems are evaluated using the same protocol. The results show an increase in effective range with some differences between the different enhancement systems.

  13. Theory, modeling and simulation: Annual report 1993

    Energy Technology Data Exchange (ETDEWEB)

    Dunning, T.H. Jr.; Garrett, B.C.

    1994-07-01

    Developing the knowledge base needed to address the environmental restoration issues of the US Department of Energy requires a fundamental understanding of molecules and their interactions in insolation and in liquids, on surfaces, and at interfaces. To meet these needs, the PNL has established the Environmental and Molecular Sciences Laboratory (EMSL) and will soon begin construction of a new, collaborative research facility devoted to advancing the understanding of environmental molecular science. Research in the Theory, Modeling, and Simulation program (TMS), which is one of seven research directorates in the EMSL, will play a critical role in understanding molecular processes important in restoring DOE`s research, development and production sites, including understanding the migration and reactions of contaminants in soils and groundwater, the development of separation process for isolation of pollutants, the development of improved materials for waste storage, understanding the enzymatic reactions involved in the biodegradation of contaminants, and understanding the interaction of hazardous chemicals with living organisms. The research objectives of the TMS program are to apply available techniques to study fundamental molecular processes involved in natural and contaminated systems; to extend current techniques to treat molecular systems of future importance and to develop techniques for addressing problems that are computationally intractable at present; to apply molecular modeling techniques to simulate molecular processes occurring in the multispecies, multiphase systems characteristic of natural and polluted environments; and to extend current molecular modeling techniques to treat complex molecular systems and to improve the reliability and accuracy of such simulations. The program contains three research activities: Molecular Theory/Modeling, Solid State Theory, and Biomolecular Modeling/Simulation. Extended abstracts are presented for 89 studies.

  14. Theory, modeling and simulation: Annual report 1993

    International Nuclear Information System (INIS)

    Dunning, T.H. Jr.; Garrett, B.C.

    1994-07-01

    Developing the knowledge base needed to address the environmental restoration issues of the US Department of Energy requires a fundamental understanding of molecules and their interactions in insolation and in liquids, on surfaces, and at interfaces. To meet these needs, the PNL has established the Environmental and Molecular Sciences Laboratory (EMSL) and will soon begin construction of a new, collaborative research facility devoted to advancing the understanding of environmental molecular science. Research in the Theory, Modeling, and Simulation program (TMS), which is one of seven research directorates in the EMSL, will play a critical role in understanding molecular processes important in restoring DOE's research, development and production sites, including understanding the migration and reactions of contaminants in soils and groundwater, the development of separation process for isolation of pollutants, the development of improved materials for waste storage, understanding the enzymatic reactions involved in the biodegradation of contaminants, and understanding the interaction of hazardous chemicals with living organisms. The research objectives of the TMS program are to apply available techniques to study fundamental molecular processes involved in natural and contaminated systems; to extend current techniques to treat molecular systems of future importance and to develop techniques for addressing problems that are computationally intractable at present; to apply molecular modeling techniques to simulate molecular processes occurring in the multispecies, multiphase systems characteristic of natural and polluted environments; and to extend current molecular modeling techniques to treat complex molecular systems and to improve the reliability and accuracy of such simulations. The program contains three research activities: Molecular Theory/Modeling, Solid State Theory, and Biomolecular Modeling/Simulation. Extended abstracts are presented for 89 studies

  15. A simple way to improve AGN feedback prescription in SPH simulations

    Science.gov (United States)

    Zubovas, Kastytis; Bourne, Martin A.; Nayakshin, Sergei

    2016-03-01

    Active galactic nuclei (AGN) feedback is an important ingredient in galaxy evolution, however its treatment in numerical simulations is necessarily approximate, requiring subgrid prescriptions due to the dynamical range involved in the calculations. We present a suite of smoothed particle hydrodynamics simulations designed to showcase the importance of the choice of a particular subgrid prescription for AGN feedback. We concentrate on two approaches to treating wide-angle AGN outflows: thermal feedback, where thermal and kinetic energy is injected into the gas surrounding the supermassive black hole (SMBH) particle, and virtual particle feedback, where energy is carried by tracer particles radially away from the AGN. We show that the latter model produces a far more complex structure around the SMBH, which we argue is a more physically correct outcome. We suggest a simple improvement to the thermal feedback model - injecting the energy into a cone, rather than spherically symmetrically - and show that this markedly improves the agreement between the two prescriptions, without requiring any noticeable increase in the computational cost of the simulation.

  16. An improved ghost-cell immersed boundary method for compressible flow simulations

    KAUST Repository

    Chi, Cheng

    2016-05-20

    This study presents an improved ghost-cell immersed boundary approach to represent a solid body in compressible flow simulations. In contrast to the commonly used approaches, in the present work ghost cells are mirrored through the boundary described using a level-set method to farther image points, incorporating a higher-order extra/interpolation scheme for the ghost cell values. A sensor is introduced to deal with image points near the discontinuities in the flow field. Adaptive mesh refinement (AMR) is used to improve the representation of the geometry efficiently in the Cartesian grid system. The improved ghost-cell method is validated against four test cases: (a) double Mach reflections on a ramp, (b) smooth Prandtl-Meyer expansion flows, (c) supersonic flows in a wind tunnel with a forward-facing step, and (d) supersonic flows over a circular cylinder. It is demonstrated that the improved ghost-cell method can reach the accuracy of second order in L1 norm and higher than first order in L∞ norm. Direct comparisons against the cut-cell method demonstrate that the improved ghost-cell method is almost equally accurate with better efficiency for boundary representation in high-fidelity compressible flow simulations. Copyright © 2016 John Wiley & Sons, Ltd.

  17. Surface improvement for inside surface of small diameter pipes by laser cladding technique

    International Nuclear Information System (INIS)

    Irisawa, Toshio; Morishige, Norio; Umemoto, Tadahiro; Ono, Kazumichi; Hamaoka, Tadashi; Tanaka, Atsushi

    1991-01-01

    A laser cladding technique has been used for surface improvement in controlling the composition of a metal surface. Recent high power YAG laser development gives an opportunity to use this laser cladding technique for various applications. A YAG laser beam can be transmitted through an optical fiber for a long distance and through narrow spaces. YAG laser cladding was studied for developing alloy steel to prevent stress corrosion cracking in austenitic stainless steel piping. In order to make a cladding layer, mixed metal powder was on the inside surface of the piping using an organic binder. Subsequently the powder beds were melted with a YAG laser beam transmitted through an optical fiber. This paper introduces the Laser cladding technique for surface improvement for the inside surface of a small diameter pipe. (author)

  18. Simulation-Based Mastery Learning with Deliberate Practice Improves Clinical Performance in Spinal Anesthesia

    Directory of Open Access Journals (Sweden)

    Ankeet D. Udani

    2014-01-01

    Full Text Available Introduction. Properly performing a subarachnoid block (SAB is a competency expected of anesthesiology residents. We aimed to determine if adding simulation-based deliberate practice to a base curriculum improved performance of a SAB. Methods. 21 anesthesia residents were enrolled. After baseline assessment of SAB on a task-trainer, all residents participated in a base curriculum. Residents were then randomized so that half received additional deliberate practice including repetition and expert-guided, real-time feedback. All residents were then retested for technique. SABs on all residents’ next three patients were evaluated in the operating room (OR. Results. Before completing the base curriculum, the control group completed 81% of a 16-item performance checklist on the task-trainer and this increased to 91% after finishing the base curriculum (P<0.02. The intervention group also increased the percentage of checklist tasks properly completed from 73% to 98%, which was a greater increase than observed in the control group (P<0.03. The OR time required to perform SAB was not different between groups. Conclusions. The base curriculum significantly improved resident SAB performance. Deliberate practice training added a significant, independent, incremental benefit. The clinical impact of the deliberate practice intervention in the OR on patient care is unclear.

  19. Simulation-based mastery learning with deliberate practice improves clinical performance in spinal anesthesia.

    Science.gov (United States)

    Udani, Ankeet D; Macario, Alex; Nandagopal, Kiruthiga; Tanaka, Maria A; Tanaka, Pedro P

    2014-01-01

    Introduction. Properly performing a subarachnoid block (SAB) is a competency expected of anesthesiology residents. We aimed to determine if adding simulation-based deliberate practice to a base curriculum improved performance of a SAB. Methods. 21 anesthesia residents were enrolled. After baseline assessment of SAB on a task-trainer, all residents participated in a base curriculum. Residents were then randomized so that half received additional deliberate practice including repetition and expert-guided, real-time feedback. All residents were then retested for technique. SABs on all residents' next three patients were evaluated in the operating room (OR). Results. Before completing the base curriculum, the control group completed 81% of a 16-item performance checklist on the task-trainer and this increased to 91% after finishing the base curriculum (P < 0.02). The intervention group also increased the percentage of checklist tasks properly completed from 73% to 98%, which was a greater increase than observed in the control group (P < 0.03). The OR time required to perform SAB was not different between groups. Conclusions. The base curriculum significantly improved resident SAB performance. Deliberate practice training added a significant, independent, incremental benefit. The clinical impact of the deliberate practice intervention in the OR on patient care is unclear.

  20. Improved simulation of poorly drained forests using Biome-BGC.

    Science.gov (United States)

    Bond-Lamberty, Ben; Gower, Stith T; Ahl, Douglas E

    2007-05-01

    Forested wetlands and peatlands are important in boreal and terrestrial biogeochemical cycling, but most general-purpose forest process models are designed and parameterized for upland systems. We describe changes made to Biome-BGC, an ecophysiological process model, that improve its ability to simulate poorly drained forests. Model changes allowed for: (1) lateral water inflow from a surrounding watershed, and variable surface and subsurface drainage; (2) adverse effects of anoxic soil on decomposition and nutrient mineralization; (3) closure of leaf stomata in flooded soils; and (4) growth of nonvascular plants (i.e., bryophytes). Bryophytes were treated as ectohydric broadleaf evergreen plants with zero stomatal conductance, whose cuticular conductance to CO(2) was dependent on plant water content. Individual model changes were parameterized with published data, and ecosystem-level model performance was assessed by comparing simulated output to field data from the northern BOREAS site in Manitoba, Canada. The simulation of the poorly drained forest model exhibited reduced decomposition and vascular plant growth (-90%) compared with that of the well-drained forest model; the integrated bryophyte photosynthetic response accorded well with published data. Simulated net primary production, biomass and soil carbon accumulation broadly agreed with field measurements, although simulated net primary production was higher than observed data in well-drained stands. Simulated net primary production in the poorly drained forest was most sensitive to oxygen restriction on soil processes, and secondarily to stomatal closure in flooded conditions. The modified Biome-BGC remains unable to simulate true wetlands that are subject to prolonged flooding, because it does not track organic soil formation, water table changes, soil redox potential or anaerobic processes.

  1. Visual interrogation of gyrokinetic particle simulations

    International Nuclear Information System (INIS)

    Jones, Chad; Ma, K-L; Sanderson, Allen; Myers, Lee Roy Jr

    2007-01-01

    Gyrokinetic particle simulations are critical to the study of anomalous energy transport associated with plasma microturbulence in magnetic confinement fusion experiments. The simulations are conducted on massively parallel computers and produce large quantities of particles, variables, and time steps, thus presenting a formidable challenge to data analysis tasks. We present two new visualization techniques for scientists to improve their understanding of the time-varying, multivariate particle data. One technique allows scientists to examine correlations in multivariate particle data with tightly coupled views of the data in both physical space and variable space, and to visually identify and track features of interest. The second technique, built into SCIRun, allows scientists to perform range-based queries over a series of time slices and visualize the resulting particles using glyphs. The ability to navigate the multiple dimensions of the particle data, as well as query individual or a collection of particles, enables scientists to not only validate their simulations but also discover new phenomena in their data

  2. Improving snow water equivalent simulations in an alpine basin using blended gage precipitation and snow pillow measurements

    Science.gov (United States)

    Sohrabi, M.; Safeeq, M.; Conklin, M. H.

    2017-12-01

    Snowpack is a critical freshwater reservoir that sustains ecosystem, natural habitat, hydropower, agriculture, and urban water supply in many areas around the world. Accurate estimation of basin scale snow water equivalent (SWE), through both measurement and modeling, has been significantly recognized to improve regional water resource management. Recent advances in remote data acquisition techniques have improved snow measurements but our ability to model snowpack evolution is largely hampered by poor knowledge of inherently variable high-elevation precipitation patterns. For a variety of reasons, majority of the precipitation gages are located in low and mid-elevation range and function as drivers for basin scale hydrologic modeling. Here, we blend observed gage precipitation from low and mid-elevation with point observations of SWE from high-elevation snow pillow into a physically based snow evolution model (SnowModel) to better represent the basin-scale precipitation field and improve snow simulations. To do this, we constructed two scenarios that differed in only precipitation. In WTH scenario, we forced the SnowModel using spatially distributed gage precipitation data. In WTH+SP scenario, the model was forced with spatially distributed precipitation data derived from gage precipitation along with observed precipitation from snow pillows. Since snow pillows do not directly measure precipitation, we uses positive change in SWE as a proxy for precipitation. The SnowModel was implemented at daily time step and 100 m resolution for the Kings River Basin, USA over 2000-2014. Our results show an improvement in snow simulation under WTH+SP as compared to WTH scenario, which can be attributed to better representation in high-elevation precipitation patterns under WTH+SP. The average Nash Sutcliffe efficiency over all snow pillow and course sites was substantially higher for WTH+SP (0.77) than for WTH scenario (0.47). The maximum difference in observed and simulated

  3. Numerical analysis of high-power broad-area laser diode with improved heat sinking structure using epitaxial liftoff technique

    Science.gov (United States)

    Kim, Younghyun; Sung, Yunsu; Yang, Jung-Tack; Choi, Woo-Young

    2018-02-01

    The characteristics of high-power broad-area laser diodes with the improved heat sinking structure are numerically analyzed by a technology computer-aided design based self-consistent electro-thermal-optical simulation. The high-power laser diodes consist of a separate confinement heterostructure of a compressively strained InGaAsP quantum well and GaInP optical cavity layers, and a 100-μm-wide rib and a 2000-μm long cavity. In order to overcome the performance deteriorations of high-power laser diodes caused by self-heating such as thermal rollover and thermal blooming, we propose the high-power broad-area laser diode with improved heat-sinking structure, which another effective heat-sinking path toward the substrate side is added by removing a bulk substrate. It is possible to obtain by removing a 400-μm-thick GaAs substrate with an AlAs sacrificial layer utilizing well-known epitaxial liftoff techniques. In this study, we present the performance improvement of the high-power laser diode with the heat-sinking structure by suppressing thermal effects. It is found that the lateral far-field angle as well as quantum well temperature is expected to be improved by the proposed heat-sinking structure which is required for high beam quality and optical output power, respectively.

  4. How to Use SANC to Improve the PHOTOS Monte Carlo Simulation of Bremsstrahlung In Leptonic W-Boson Decays

    International Nuclear Information System (INIS)

    Nanava, G.; ); Was, Z.; )

    2003-01-01

    Using the SANC system we study the one-loop electroweak standard model predictions, including virtual and real photon emission, for the decays of the on-shell vector boson, W → lν l γ. The complete one-loop corrections and exact photon emission matrix element are taken into account. For the phase space integration, the Monte Carlo technique is used. This provides a useful element, first for the evaluation of the theoretical uncertainty of PHOTOS. Later we analyse the source of the differences between SANC and PHOTOS and we calculate the additional weight, which once installed, improves predictions of PHOTOS simulations. We can conclude that, after the correction of the weight is implemented, the theoretical uncertainty of PHOTOS simulations due to an incomplete first-order matrix element is reduced to below, for observables not tagging the photon in a direct way, and to 10% otherwise. This is interesting for applications in the phenomenology of the ongoing LEP2 and future LC and LHC experimental studies. (author)

  5. Using a Competitive Approach to Improve Military Simulation Artificial Intelligence Design

    National Research Council Canada - National Science Library

    Stoykov, Sevdalin

    2008-01-01

    ...) design can lead to improvement of the AI solutions used in military simulations. To demonstrate the potential of the competitive approach, ORTS, a real-time strategy game engine, and its competition setup are used...

  6. Improvement of the technique in treatment of internal hemorrhoids with Nd:YAG laser

    Science.gov (United States)

    Bao, Xiao-qing; Zhu, Jing; Shi, Hong-Min

    2005-07-01

    Objective: To observe and study the improvement of the technique in treatment of internal hemorrhoids with Nd:YAG laser and evaluate the effective rate. Methods: 60 patients of internal hemorrhoids were treated with Nd:YAG laser (10-15mw) irradiating on the mucosa of the lesions. Results: Among 60 patients, 57 patients were primarily cured with one treatment, 3 patients were primarily cured with two treatments. The effective rate was 95% with one treatment, and it reached to 100% with two treatments. Conclusions: the improvement of the technique in treatment of internal hemorrhoids with Nd:YAG laser is effective and easy to operate.

  7. Improvement technique of sensitized HAZ by GTAW cladding applied to a BWR power plant

    International Nuclear Information System (INIS)

    Tujimura, Hiroshi; Tamai, Yasumasa; Furukawa, Hideyasu; Kurosawa, Kouichi; Chiba, Isao; Nomura, Keiichi.

    1995-01-01

    A SCC(Stress Corrosion Cracking)-resistant technique, in which the sleeve installed by expansion is melted by GTAW process without filler metal with outside water cooling, was developed. The technique was applied to ICM (In-Core Monitor) housings of a BWR power plant in 1993. The ICM housings of which materials are type 304 Stainless Steels are sensitized with high tensile residual stresses by welding to the RPV (Reactor Pressure Vessel). As the result, ICM housings have potential of SCC initiation. Therefore, the improvement technique resistant to SCC was needed. The technique can improve chemical composition of the housing inside and residual stresses of the housing outside at the same time. Sensitization of the housing inner surface area is eliminated by replacing low-carbon with proper-ferrite microstructure clad. High tensile residual stresses of housing outside surface area is improved into compressive side. Compressive stresses of outside surface are induced by thermal stresses which are caused by inside cladding with outside water cooling. The clad is required to be low-carbon metal with proper ferrite and not to have the new sensitized HAZ (Heat Affected Zone) on the surface by cladding. The effect of the technique was qualified by SCC test, chemical composition check, ferrite content measurement and residual stresses measurement etc. All equipment for remote application were developed and qualified, too. The technique was successfully applied to a BWR plant after sufficient training

  8. Simulation-based medical education training improves short and long-term competency in, and knowledge of central venous catheter insertion: A before and after intervention study.

    Science.gov (United States)

    Cartier, Vanessa; Inan, Cigdem; Zingg, Walter; Delhumeau, Cecile; Walder, Bernard; Savoldelli, Georges L

    2016-08-01

    Multimodal educational interventions have been shown to improve short-term competency in, and knowledge of central venous catheter (CVC) insertion. To evaluate the effectiveness of simulation-based medical education training in improving short and long-term competency in, and knowledge of CVC insertion. Before and after intervention study. University Geneva Hospital, Geneva, Switzerland, between May 2008 and January 2012. Residents in anaesthesiology aware of the Seldinger technique for vascular puncture. Participants attended a half-day course on CVC insertion. Learning objectives included work organization, aseptic technique and prevention of CVC complications. CVC insertion competency was tested pretraining, posttraining and then more than 2 years after training (sustainability phase). The primary study outcome was competency as measured by a global rating scale of technical skills, a hand hygiene compliance score and a checklist compliance score. Secondary outcome was knowledge as measured by a standardised pretraining and posttraining multiple-choice questionnaire. Statistical analyses were performed using paired Student's t test or Wilcoxon signed-rank test. Thirty-seven residents were included; 18 were tested in the sustainability phase (on average 34 months after training). The average global rating of skills was 23.4 points (±SD 4.08) before training, 32.2 (±4.51) after training (P Simulation-based medical education training was effective in improving short and long-term competency in, and knowledge of CVC insertion.

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

    Science.gov (United States)

    Uchida, Masafumi

    2014-04-01

    A few years ago it could take several hours to complete a 3D image using a 3D workstation. Thanks to advances in computer science, obtaining results of interest now requires only a few minutes. Many recent 3D workstations or multimedia computers are equipped with onboard 3D virtual patient modeling software, which enables patient-specific preoperative assessment and virtual planning, navigation, and tool positioning. Although medical 3D imaging can now be conducted using various modalities, including computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and ultrasonography (US) among others, the highest quality images are obtained using CT data, and CT images are now the most commonly used source of data for 3D simulation and navigation image. If the 2D source image is bad, no amount of 3D image manipulation in software will provide a quality 3D image. In this exhibition, the recent advances in CT imaging technique and 3D visualization of the hepatobiliary and pancreatic abnormalities are featured, including scan and image reconstruction technique, contrast-enhanced techniques, new application of advanced CT scan techniques, and new virtual reality simulation and navigation imaging. © 2014 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

  10. Simulation of white light generation and near light bullets using a novel numerical technique

    Science.gov (United States)

    Zia, Haider

    2018-01-01

    An accurate and efficient simulation has been devised, employing a new numerical technique to simulate the derivative generalised non-linear Schrödinger equation in all three spatial dimensions and time. The simulation models all pertinent effects such as self-steepening and plasma for the non-linear propagation of ultrafast optical radiation in bulk material. Simulation results are compared to published experimental spectral data of an example ytterbium aluminum garnet system at 3.1 μm radiation and fits to within a factor of 5. The simulation shows that there is a stability point near the end of the 2 mm crystal where a quasi-light bullet (spatial temporal soliton) is present. Within this region, the pulse is collimated at a reduced diameter (factor of ∼2) and there exists a near temporal soliton at the spatial center. The temporal intensity within this stable region is compressed by a factor of ∼4 compared to the input. This study shows that the simulation highlights new physical phenomena based on the interplay of various linear, non-linear and plasma effects that go beyond the experiment and is thus integral to achieving accurate designs of white light generation systems for optical applications. An adaptive error reduction algorithm tailor made for this simulation will also be presented in appendix.

  11. A Fixed-Wing Aircraft Simulation Tool for Improving the efficiency of DoD Acquisition

    Science.gov (United States)

    2015-10-05

    simulation tool , CREATETM-AV Helios [12-14], a high fidelity rotary wing vehicle simulation tool , and CREATETM-AV DaVinci [15-16], a conceptual through...05/2015 Oct 2008-Sep 2015 A Fixed-Wing Aircraft Simulation Tool for Improving the Efficiency of DoD Acquisition Scott A. Morton and David R...multi-disciplinary fixed-wing virtual aircraft simulation tool incorporating aerodynamics, structural dynamics, kinematics, and kinetics. Kestrel allows

  12. Improvements on nonlinear gyrokinetic particle simulations based on δf-discretization scheme

    International Nuclear Information System (INIS)

    Zorat, R.; Tessarotto, M.

    1998-01-01

    In this work various issues regarding the definition of improved theoretical models appropriate to describe the dynamics of confined magnetoplasmas by particle simulation methods are proposed. These concern in particular an improved non linear δf discretization scheme and the treatment of binary, i.e. Coulomb, and collective interactions. (orig.)

  13. Interprofessional simulation training improves knowledge and teamwork in nursing and medical students during internal medicine clerkship.

    Science.gov (United States)

    Tofil, Nancy M; Morris, Jason L; Peterson, Dawn Taylor; Watts, Penni; Epps, Chad; Harrington, Kathy F; Leon, Kevin; Pierce, Caleb; White, Marjorie Lee

    2014-03-01

    Simulation is effective at improving healthcare students' knowledge and communication. Despite increasingly interprofessional approaches to medicine, most studies demonstrate these effects in isolation. We enhanced an existing internal medicine curriculum with immersive interprofessional simulations. For ten months, third-year medical students and senior nursing students were recruited for four, 1-hour simulations. Scenarios included myocardial infarction, pancreatitis/hyperkalemia, upper gastrointestinal bleed, and chronic obstructive pulmonary disease exacerbation. After each scenario, experts in medicine, nursing, simulation, and adult learning facilitated a debriefing. Study measures included pre- and post-tests assessing self-efficacy, communication skills, and understanding of each profession's role. Seventy-two medical students and 30 nursing students participated. Self-efficacy communication scores improved for both (medicine, 18.9 ± 3.3 pretest vs 23.7 ± 3.7 post-test; nursing, 19.6 ± 2.7 pretest vs 24.5 ± 2.5 post-test). Both groups showed improvement in "confidence to correct another healthcare provider in a collaborative manner" (Δ = .97 medicine, Δ = 1.2 nursing). Medical students showed the most improvement in "confidence to close the loop in patient care" (Δ = .93). Nursing students showed the most improvement in "confidence to figure out roles" (Δ = 1.1). This study supports the hypothesis that interdisciplinary simulation improves each discipline's self-efficacy communication skills and understanding of each profession's role. Despite many barriers to interprofessional simulation, this model is being sustained. © 2014 Society of Hospital Medicine.

  14. Timesaving techniques for decision of electron-molecule collisions in Monte Carlo simulation of electrical discharges

    International Nuclear Information System (INIS)

    Sugawara, Hirotake; Mori, Naoki; Sakai, Yosuke; Suda, Yoshiyuki

    2007-01-01

    Techniques to reduce the computational load for determination of electron-molecule collisions in Monte Carlo simulations of electrical discharges have been presented. By enhancing the detection efficiency of the no-collision case in the decision scheme of the collisional events, we can decrease the frequency of access to time-consuming subroutines to calculate the electron collision cross sections of the gas molecules for obtaining the collision probability. A benchmark test and an estimation to evaluate the present techniques have shown a practical timesaving efficiency

  15. An empirical technique to improve MRA imagin

    Directory of Open Access Journals (Sweden)

    Sonia Rauf

    2016-07-01

    Full Text Available In the Region Growing Algorithm (RGA results of segmentation are totally dependent on the selection of seed point, as an inappropriate seed point may lead to poor segmentation. However, the majority of MRA (Magnetic Resonance Angiography datasets do not contain required region (vessels in starting slices. An Enhanced Region Growing Algorithm (ERGA is proposed for blood vessel segmentation. The ERGA automatically calculates the threshold value on the basis of maximum intensity values of all the slices and selects an appropriate starting slice of the image which has a appropriate seed point. We applied our proposed technique on different patients of MRA datasets of different resolutions and have got improved segmented images with reduction of noise as compared to tradition RGA.

  16. Improved real-time dynamics from imaginary frequency lattice simulations

    Directory of Open Access Journals (Sweden)

    Pawlowski Jan M.

    2018-01-01

    Full Text Available The computation of real-time properties, such as transport coefficients or bound state spectra of strongly interacting quantum fields in thermal equilibrium is a pressing matter. Since the sign problem prevents a direct evaluation of these quantities, lattice data needs to be analytically continued from the Euclidean domain of the simulation to Minkowski time, in general an ill-posed inverse problem. Here we report on a novel approach to improve the determination of real-time information in the form of spectral functions by setting up a simulation prescription in imaginary frequencies. By carefully distinguishing between initial conditions and quantum dynamics one obtains access to correlation functions also outside the conventional Matsubara frequencies. In particular the range between ω0 and ω1 = 2πT, which is most relevant for the inverse problem may be more highly resolved. In combination with the fact that in imaginary frequencies the kernel of the inverse problem is not an exponential but only a rational function we observe significant improvements in the reconstruction of spectral functions, demonstrated in a simple 0+1 dimensional scalar field theory toy model.

  17. Improved real-time dynamics from imaginary frequency lattice simulations

    Science.gov (United States)

    Pawlowski, Jan M.; Rothkopf, Alexander

    2018-03-01

    The computation of real-time properties, such as transport coefficients or bound state spectra of strongly interacting quantum fields in thermal equilibrium is a pressing matter. Since the sign problem prevents a direct evaluation of these quantities, lattice data needs to be analytically continued from the Euclidean domain of the simulation to Minkowski time, in general an ill-posed inverse problem. Here we report on a novel approach to improve the determination of real-time information in the form of spectral functions by setting up a simulation prescription in imaginary frequencies. By carefully distinguishing between initial conditions and quantum dynamics one obtains access to correlation functions also outside the conventional Matsubara frequencies. In particular the range between ω0 and ω1 = 2πT, which is most relevant for the inverse problem may be more highly resolved. In combination with the fact that in imaginary frequencies the kernel of the inverse problem is not an exponential but only a rational function we observe significant improvements in the reconstruction of spectral functions, demonstrated in a simple 0+1 dimensional scalar field theory toy model.

  18. Improving "lab-on-a-chip" techniques using biomedical nanotechnology: a review.

    Science.gov (United States)

    Gorjikhah, Fatemeh; Davaran, Soodabeh; Salehi, Roya; Bakhtiari, Mohsen; Hasanzadeh, Arash; Panahi, Yunes; Emamverdy, Masumeh; Akbarzadeh, Abolfazl

    2016-11-01

    Nanotechnology and its applications in biomedical sciences principally in molecular nanodiagnostics are known as nanomolecular diagnostics, which provides new options for clinical nanodiagnostic techniques. Molecular nanodiagnostics are a critical role in the development of personalized medicine, which features point-of care performance of diagnostic procedure. This can to check patients at point-of-care facilities or in remote or resource-poor locations, therefore reducing checking time from days to minutes. In this review, applications of nanotechnology suited to biomedicine are discussed in two main class: biomedical applications for use inside (such as drugs, diagnostic techniques, prostheses, and implants) and outside the body (such as "lab-on-a-chip" techniques). A lab-on-a-chip (LOC) is a tool that incorporates numerous laboratory tasks onto a small device, usually only millimeters or centimeters in size. Finally, are discussed the applications of biomedical nanotechnology in improving "lab-on-a-chip" techniques.

  19. Improved data visualization techniques for analyzing macromolecule structural changes.

    Science.gov (United States)

    Kim, Jae Hyun; Iyer, Vidyashankara; Joshi, Sangeeta B; Volkin, David B; Middaugh, C Russell

    2012-10-01

    The empirical phase diagram (EPD) is a colored representation of overall structural integrity and conformational stability of macromolecules in response to various environmental perturbations. Numerous proteins and macromolecular complexes have been analyzed by EPDs to summarize results from large data sets from multiple biophysical techniques. The current EPD method suffers from a number of deficiencies including lack of a meaningful relationship between color and actual molecular features, difficulties in identifying contributions from individual techniques, and a limited ability to be interpreted by color-blind individuals. In this work, three improved data visualization approaches are proposed as techniques complementary to the EPD. The secondary, tertiary, and quaternary structural changes of multiple proteins as a function of environmental stress were first measured using circular dichroism, intrinsic fluorescence spectroscopy, and static light scattering, respectively. Data sets were then visualized as (1) RGB colors using three-index EPDs, (2) equiangular polygons using radar charts, and (3) human facial features using Chernoff face diagrams. Data as a function of temperature and pH for bovine serum albumin, aldolase, and chymotrypsin as well as candidate protein vaccine antigens including a serine threonine kinase protein (SP1732) and surface antigen A (SP1650) from S. pneumoniae and hemagglutinin from an H1N1 influenza virus are used to illustrate the advantages and disadvantages of each type of data visualization technique. Copyright © 2012 The Protein Society.

  20. Use of progesterone radioimmunoassay techniques for improving reproduction performances in dary cattles

    International Nuclear Information System (INIS)

    Benyoucef, M.T.; Benabdelaziz, A.; Khelili, R.

    1990-07-01

    This report deals with the first measurements of progesterone, by radioimmunoassay (P4-PIA) in blood samples, to assess fertility in livestock (cattle) in Algeria, by improvement of the level of reproduction management. For this purpose, the results obtained throughout first analysis of P4 on a sample of 15 bovines females, composed by 12 heifers and 3 cows confirm the efficiency of the techniques in improving dary cattle reproduction performances. Ovarian activity can be determined for cows at the moment of post partum and for heifers before breeding as well as, pregnancy confirmation on breeding heifers. It is interesting to extend the experiments using these techniques to a higher number of livestocks (breeds and species) and to develop new research subjects in this field

  1. Simulation tools for industrial applications of phased array inspection techniques

    International Nuclear Information System (INIS)

    Mahaut, St.; Roy, O.; Chatillon, S.; Calmon, P.

    2001-01-01

    Ultrasonic phased arrays techniques have been developed at the French Atomic Energy Commission in order to improve defects characterization and adaptability to various inspection configuration (complex geometry specimen). Such transducers allow 'standard' techniques - adjustable beam-steering and focusing -, or more 'advanced' techniques - self-focusing on defects for instance -. To estimate the performances of those techniques, models have been developed, which allows to compute the ultrasonic field radiated by an arbitrary phased array transducer through any complex specimen, and to predict the ultrasonic response of various defects inspected with a known beam. Both modeling applications are gathered in the Civa software, dedicated to NDT expertise. The use of those complementary models allows to evaluate the ability of a phased array to steer and focus the ultrasonic beam, and therefore its relevancy to detect and characterize defects. These models are specifically developed to give accurate solutions to realistic inspection applications. This paper briefly describes the CIVA models, and presents some applications dedicated to the inspection of complex specimen containing various defects with a phased array used to steer and focus the beam. Defect detection and characterization performances are discussed for the various configurations. Some experimental validation of both models are also presented. (authors)

  2. Estimation variance bounds of importance sampling simulations in digital communication systems

    Science.gov (United States)

    Lu, D.; Yao, K.

    1991-01-01

    In practical applications of importance sampling (IS) simulation, two basic problems are encountered, that of determining the estimation variance and that of evaluating the proper IS parameters needed in the simulations. The authors derive new upper and lower bounds on the estimation variance which are applicable to IS techniques. The upper bound is simple to evaluate and may be minimized by the proper selection of the IS parameter. Thus, lower and upper bounds on the improvement ratio of various IS techniques relative to the direct Monte Carlo simulation are also available. These bounds are shown to be useful and computationally simple to obtain. Based on the proposed technique, one can readily find practical suboptimum IS parameters. Numerical results indicate that these bounding techniques are useful for IS simulations of linear and nonlinear communication systems with intersymbol interference in which bit error rate and IS estimation variances cannot be obtained readily using prior techniques.

  3. Two Hours of Teamwork Training Improves Teamwork in Simulated Cardiopulmonary Arrest Events.

    Science.gov (United States)

    Mahramus, Tara L; Penoyer, Daleen A; Waterval, Eugene M E; Sole, Mary L; Bowe, Eileen M

    2016-01-01

    Teamwork during cardiopulmonary arrest events is important for resuscitation. Teamwork improvement programs are usually lengthy. This study assessed the effectiveness of a 2-hour teamwork training program. A prospective, pretest/posttest, quasi-experimental design assessed the teamwork training program targeted to resident physicians, nurses, and respiratory therapists. Participants took part in a simulated cardiac arrest. After the simulation, participants and trained observers assessed perceptions of teamwork using the Team Emergency Assessment Measure (TEAM) tool (ratings of 0 [low] to 4 [high]). A debriefing and 45 minutes of teamwork education followed. Participants then took part in a second simulated cardiac arrest scenario. Afterward, participants and observers assessed teamwork. Seventy-three team members participated-resident physicians (25%), registered nurses (32%), and respiratory therapists (41%). The physicians had significantly less experience on code teams (P teamwork scores were 2.57 to 2.72. Participants' mean (SD) scores on the TEAM tool for the first and second simulations were 3.2 (0.5) and 3.7 (0.4), respectively (P teamwork educational intervention resulted in improved perceptions of teamwork behaviors. Participants reported interactions with other disciplines, teamwork behavior education, and debriefing sessions were beneficial for enhancing the program.

  4. The new ATLAS Fast Calorimeter Simulation

    CERN Document Server

    Jacka, Petr; The ATLAS collaboration

    2018-01-01

    With the huge amount of data collected with ATLAS, there is a need to produce a large number of simulated events. These productions are very CPU and time consuming when using the full GEANT4 simulation. FastCaloSim is a program to quickly simulate the ATLAS calorimeter response, based on a parameterization of the GEANT4 energy deposits of several kinds of particles in a grid of energy and eta. A new version of FastCaloSim is under development and its integration into the ATLAS simulation infrastructure is ongoing. The use of machine learning techniques improves the performance and decreases the memory usage. Dedicated parameterizations for the forward calorimeters are being studied. First results of the new FastCaloSim show substantial improvements of the description of energy and shower shape variables, including the variables for jet substructure.

  5. Improving reticle defect disposition via fully automated lithography simulation

    Science.gov (United States)

    Mann, Raunak; Goodman, Eliot; Lao, Keith; Ha, Steven; Vacca, Anthony; Fiekowsky, Peter; Fiekowsky, Dan

    2016-03-01

    Most advanced wafer fabs have embraced complex pattern decoration, which creates numerous challenges during in-fab reticle qualification. These optical proximity correction (OPC) techniques create assist features that tend to be very close in size and shape to the main patterns as seen in Figure 1. A small defect on an assist feature will most likely have little or no impact on the fidelity of the wafer image, whereas the same defect on a main feature could significantly decrease device functionality. In order to properly disposition these defects, reticle inspection technicians need an efficient method that automatically separates main from assist features and predicts the resulting defect impact on the wafer image. Analysis System (ADAS) defect simulation system[1]. Up until now, using ADAS simulation was limited to engineers due to the complexity of the settings that need to be manually entered in order to create an accurate result. A single error in entering one of these values can cause erroneous results, therefore full automation is necessary. In this study, we propose a new method where all needed simulation parameters are automatically loaded into ADAS. This is accomplished in two parts. First we have created a scanner parameter database that is automatically identified from mask product and level names. Second, we automatically determine the appropriate simulation printability threshold by using a new reference image (provided by the inspection tool) that contains a known measured value of the reticle critical dimension (CD). This new method automatically loads the correct scanner conditions, sets the appropriate simulation threshold, and automatically measures the percentage of CD change caused by the defect. This streamlines qualification and reduces the number of reticles being put on hold, waiting for engineer review. We also present data showing the consistency and reliability of the new method, along with the impact on the efficiency of in

  6. Advanced sensing techniques for cognitive radio

    CERN Document Server

    Zhao, Guodong; Li, Shaoqian

    2017-01-01

    This SpringerBrief investigates advanced sensing techniques to detect and estimate the primary receiver for cognitive radio systems. Along with a comprehensive overview of existing spectrum sensing techniques, this brief focuses on the design of new signal processing techniques, including the region-based sensing, jamming-based probing, and relay-based probing. The proposed sensing techniques aim to detect the nearby primary receiver and estimate the cross-channel gain between the cognitive transmitter and primary receiver. The performance of the proposed algorithms is evaluated by simulations in terms of several performance parameters, including detection probability, interference probability, and estimation error. The results show that the proposed sensing techniques can effectively sense the primary receiver and improve the cognitive transmission throughput. Researchers and postgraduate students in electrical engineering will find this an exceptional resource.

  7. Simulation and optimization of agricultural product supply chain system based on Witness

    Directory of Open Access Journals (Sweden)

    Jiandong Liu

    2017-03-01

    Full Text Available Researches on agricultural product supply chain have important implications for improving the efficiency of agricultural products circulation, strengthening the construction of agricultural market system, promoting agricultural modernization and solving the three rural issues. Agricultural product supply chain system has begun to be optimized through simulation technique. In this paper, agricultural product supply chain system is reasonably simplified and assumed. A simulation model was developed by using the simulation software Wit-ness to study agricultural product supply chain. Through the analysis of the simulation output data, improvement suggestions were also proposed as follows: improving the organization degree of agricultural products, improving the agricultural products processing, establishing strategic partnership and scientifically developing agricultural products logistics.

  8. Evaluation of a novel educational strategy, including inhaler-based reminder labels, to improve asthma inhaler technique.

    Science.gov (United States)

    Basheti, Iman A; Armour, Carol L; Bosnic-Anticevich, Sinthia Z; Reddel, Helen K

    2008-07-01

    To evaluate the feasibility, acceptability and effectiveness of a brief intervention about inhaler technique, delivered by community pharmacists to asthma patients. Thirty-one pharmacists received brief workshop education (Active: n=16, CONTROL: n=15). Active Group pharmacists were trained to assess and teach dry powder inhaler technique, using patient-centered educational tools including novel Inhaler Technique Labels. Interventions were delivered to patients at four visits over 6 months. At baseline, patients (Active: 53, CONTROL: 44) demonstrated poor inhaler technique (mean+/-S.D. score out of 9, 5.7+/-1.6). At 6 months, improvement in inhaler technique score was significantly greater in Active cf. CONTROL patients (2.8+/-1.6 cf. 0.9+/-1.4, p<0.001), and asthma severity was significantly improved (p=0.015). Qualitative responses from patients and pharmacists indicated a high level of satisfaction with the intervention and educational tools, both for their effectiveness and for their impact on the patient-pharmacist relationship. A simple feasible intervention in community pharmacies, incorporating daily reminders via Inhaler Technique Labels on inhalers, can lead to improvement in inhaler technique and asthma outcomes. Brief training modules and simple educational tools, such as Inhaler Technique Labels, can provide a low-cost and sustainable way of changing patient behavior in asthma, using community pharmacists as educators.

  9. A Monte Carlo simulation technique to determine the optimal portfolio

    Directory of Open Access Journals (Sweden)

    Hassan Ghodrati

    2014-03-01

    Full Text Available During the past few years, there have been several studies for portfolio management. One of the primary concerns on any stock market is to detect the risk associated with various assets. One of the recognized methods in order to measure, to forecast, and to manage the existing risk is associated with Value at Risk (VaR, which draws much attention by financial institutions in recent years. VaR is a method for recognizing and evaluating of risk, which uses the standard statistical techniques and the method has been used in other fields, increasingly. The present study has measured the value at risk of 26 companies from chemical industry in Tehran Stock Exchange over the period 2009-2011 using the simulation technique of Monte Carlo with 95% confidence level. The used variability in the present study has been the daily return resulted from the stock daily price change. Moreover, the weight of optimal investment has been determined using a hybrid model called Markowitz and Winker model in each determined stocks. The results showed that the maximum loss would not exceed from 1259432 Rials at 95% confidence level in future day.

  10. Flexible time domain averaging technique

    Science.gov (United States)

    Zhao, Ming; Lin, Jing; Lei, Yaguo; Wang, Xiufeng

    2013-09-01

    Time domain averaging(TDA) is essentially a comb filter, it cannot extract the specified harmonics which may be caused by some faults, such as gear eccentric. Meanwhile, TDA always suffers from period cutting error(PCE) to different extent. Several improved TDA methods have been proposed, however they cannot completely eliminate the waveform reconstruction error caused by PCE. In order to overcome the shortcomings of conventional methods, a flexible time domain averaging(FTDA) technique is established, which adapts to the analyzed signal through adjusting each harmonic of the comb filter. In this technique, the explicit form of FTDA is first constructed by frequency domain sampling. Subsequently, chirp Z-transform(CZT) is employed in the algorithm of FTDA, which can improve the calculating efficiency significantly. Since the signal is reconstructed in the continuous time domain, there is no PCE in the FTDA. To validate the effectiveness of FTDA in the signal de-noising, interpolation and harmonic reconstruction, a simulated multi-components periodic signal that corrupted by noise is processed by FTDA. The simulation results show that the FTDA is capable of recovering the periodic components from the background noise effectively. Moreover, it can improve the signal-to-noise ratio by 7.9 dB compared with conventional ones. Experiments are also carried out on gearbox test rigs with chipped tooth and eccentricity gear, respectively. It is shown that the FTDA can identify the direction and severity of the eccentricity gear, and further enhances the amplitudes of impulses by 35%. The proposed technique not only solves the problem of PCE, but also provides a useful tool for the fault symptom extraction of rotating machinery.

  11. Simulation Tools and Techniques for Analyzing the Impacts of Photovoltaic System Integration

    Science.gov (United States)

    Hariri, Ali

    utility simulation software. On the other hand, EMT simulation tools provide high accuracy and visibility over a wide bandwidth of frequencies at the expense of larger processing and memory requirements, limited network size, and long simulation time. Therefore, there is a gap in simulation tools and techniques that can efficiently and effectively identify potential PV impact. New planning simulation tools are needed in order to accommodate for the simulation requirements of new integrated technologies in the electric grid. The dissertation at hand starts by identifying some of the potential impacts that are caused by high PV penetration. A phasor-based quasi-static time series (QSTS) analysis tool is developed in order to study the slow dynamics that are caused by the variations in the PV generation that lead to voltage fluctuations. Moreover, some EMT simulations are performed in order to study the impacts of PV systems on the electric network harmonic levels. These studies provide insights into the type and duration of certain impacts, as well as the conditions that may lead to adverse phenomena. In addition these studies present an idea about the type of simulation tools that are sufficient for each type of study. After identifying some of the potential impacts, certain planning tools and techniques are proposed. The potential PV impacts may cause certain utilities to refrain from integrating PV systems into their networks. However, each electric network has a certain limit beyond which the impacts become substantial and may adversely interfere with the system operation and the equipment along the feeder; this limit is referred to as the hosting limit (or hosting capacity). Therefore, it is important for utilities to identify the PV hosting limit on a specific electric network in order to safely and confidently integrate the maximum possible PV systems. In the following dissertation, two approaches have been proposed for identifying the hosing limit: 1. Analytical

  12. An improved ghost-cell immersed boundary method for compressible flow simulations

    KAUST Repository

    Chi, Cheng; Lee, Bok Jik; Im, Hong G.

    2016-01-01

    This study presents an improved ghost-cell immersed boundary approach to represent a solid body in compressible flow simulations. In contrast to the commonly used approaches, in the present work ghost cells are mirrored through the boundary

  13. Systems modeling and simulation applications for critical care medicine

    Science.gov (United States)

    2012-01-01

    Critical care delivery is a complex, expensive, error prone, medical specialty and remains the focal point of major improvement efforts in healthcare delivery. Various modeling and simulation techniques offer unique opportunities to better understand the interactions between clinical physiology and care delivery. The novel insights gained from the systems perspective can then be used to develop and test new treatment strategies and make critical care delivery more efficient and effective. However, modeling and simulation applications in critical care remain underutilized. This article provides an overview of major computer-based simulation techniques as applied to critical care medicine. We provide three application examples of different simulation techniques, including a) pathophysiological model of acute lung injury, b) process modeling of critical care delivery, and c) an agent-based model to study interaction between pathophysiology and healthcare delivery. Finally, we identify certain challenges to, and opportunities for, future research in the area. PMID:22703718

  14. Systems modeling and simulation applications for critical care medicine.

    Science.gov (United States)

    Dong, Yue; Chbat, Nicolas W; Gupta, Ashish; Hadzikadic, Mirsad; Gajic, Ognjen

    2012-06-15

    Critical care delivery is a complex, expensive, error prone, medical specialty and remains the focal point of major improvement efforts in healthcare delivery. Various modeling and simulation techniques offer unique opportunities to better understand the interactions between clinical physiology and care delivery. The novel insights gained from the systems perspective can then be used to develop and test new treatment strategies and make critical care delivery more efficient and effective. However, modeling and simulation applications in critical care remain underutilized. This article provides an overview of major computer-based simulation techniques as applied to critical care medicine. We provide three application examples of different simulation techniques, including a) pathophysiological model of acute lung injury, b) process modeling of critical care delivery, and c) an agent-based model to study interaction between pathophysiology and healthcare delivery. Finally, we identify certain challenges to, and opportunities for, future research in the area.

  15. Why use case studies rather than simulation-gaming techniques or library research?

    Science.gov (United States)

    Mcdonald, S. W.

    1981-01-01

    Method which present a student with a more challenging and true to life situation of needing to conduct research in a problem solving context--and not thinking about organization of format until research and thinking are complete are investigated. Simulation-gaming techniques which attempt to teach initiative and creativity that library research are used for this purpose. However, it is shown case studies provide the greatest opportunities to engage the students in problem solving situations in which they develop skills as researchers and writers.

  16. An investigation of the efficiency in simulating 6 MV medical accelerator using OMEGA/BEAM

    International Nuclear Information System (INIS)

    Dai Zhenhui; Wang Xuetao; Zhu Lin; Zhang Yu; Liu Xiaowei

    2013-01-01

    Background: Monte Carlo simulation techniques are presently considered to be the most reliable method for radiation therapy treatment planning. However, long simulation times involved when using the general-purpose Monte Carlo code systems have led to the development of special-purpose Monte Carlo programs. Purpose: This paper attempts to improve computing efficiency for dose calculation in the EGSnrc modeling of clinical linear accelerator by selecting proper parameters. Methods: Several variance reduction techniques including uniform bremsstrahlung splitting, selective bremsstrahlung splitting, directional bremsstrahlung splitting are applied in BEAMnrc simulating medical accelerator treatment head to generate phase-space file which is selected as a source for DOSXYZnrc simulation, both photon splitting and particle recycling are used to improve the efficiency in the calculation of dose profile in water phantom. Results: The splitting number for maximum efficiency in directional bremsstrahlung splitting (no electron splitting) is 2500 in the BEAMnrc simulation. The highest efficiency of DOSXYZnrc simulation is given when photon splitting number is set to 40. Conclusions: Efficiency can be significantly improved by setting appropriate bremsstrahlung splitting and optimized photon splitting number and particle recycling number. (authors)

  17. Improving face image extraction by using deep learning technique

    Science.gov (United States)

    Xue, Zhiyun; Antani, Sameer; Long, L. R.; Demner-Fushman, Dina; Thoma, George R.

    2016-03-01

    The National Library of Medicine (NLM) has made a collection of over a 1.2 million research articles containing 3.2 million figure images searchable using the Open-iSM multimodal (text+image) search engine. Many images are visible light photographs, some of which are images containing faces ("face images"). Some of these face images are acquired in unconstrained settings, while others are studio photos. To extract the face regions in the images, we first applied one of the most widely-used face detectors, a pre-trained Viola-Jones detector implemented in Matlab and OpenCV. The Viola-Jones detector was trained for unconstrained face image detection, but the results for the NLM database included many false positives, which resulted in a very low precision. To improve this performance, we applied a deep learning technique, which reduced the number of false positives and as a result, the detection precision was improved significantly. (For example, the classification accuracy for identifying whether the face regions output by this Viola- Jones detector are true positives or not in a test set is about 96%.) By combining these two techniques (Viola-Jones and deep learning) we were able to increase the system precision considerably, while avoiding the need to manually construct a large training set by manual delineation of the face regions.

  18. Induced mutations and molecular techniques for crop improvement. Proceedings of an international symposium

    International Nuclear Information System (INIS)

    1995-01-01

    The symposium was aimed at reviewing current aspects of mutation and molecular biology techniques for use in crop improvement and to bridge the gap between practical plant breeding and molecular laboratory techniques. Over the past few years, many transgenic plants have been developed in important crops such as rice, wheat, maize, soybean, banana, cassava and cotton, as well as in many food, industrial and pharmaceutical plant species. More than 180 participants from 48 countries of which 31 were from developing countries, attended which provided a forum for the discussion of problems related to crop improvement world wide, and their possible solutions. Refs, figs and tabs

  19. Progress and improvement of KSTAR plasma control using model-based control simulators

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, Sang-hee, E-mail: hahn76@nfri.re.kr [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Welander, A.S. [General Atomics, San Diego, CA (United States); Yoon, S.W.; Bak, J.G. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Eidietis, N.W. [General Atomics, San Diego, CA (United States); Han, H.S. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Humphreys, D.A.; Hyatt, A. [General Atomics, San Diego, CA (United States); Jeon, Y.M. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Johnson, R.D. [General Atomics, San Diego, CA (United States); Kim, H.S.; Kim, J. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of); Kolemen, E.; Mueller, D. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Penaflor, B.G.; Piglowski, D.A. [General Atomics, San Diego, CA (United States); Shin, G.W. [University of Science and Technology, Daejeon (Korea, Republic of); Walker, M.L. [General Atomics, San Diego, CA (United States); Woo, M.H. [National Fusion Research Institute, 169-148 Gwahak-ro, yuseong-gu, Daejeon (Korea, Republic of)

    2014-05-15

    Superconducting tokamaks like KSTAR, EAST and ITER need elaborate magnetic controls mainly due to either the demanding experiment schedule or tighter hardware limitations caused by the superconducting coils. In order to reduce the operation runtime requirements, two types of plasma simulators for the KSTAR plasma control system (PCS) have been developed for improving axisymmetric magnetic controls. The first one is an open-loop type, which can reproduce the control done in an old shot by loading the corresponding diagnostics data and PCS setup. The other one, a closed-loop simulator based on a linear nonrigid plasma model, is designed to simulate dynamic responses of the plasma equilibrium and plasma current (I{sub p}) due to changes of the axisymmetric poloidal field (PF) coil currents, poloidal beta, and internal inductance. The closed-loop simulator is the one that actually can test and enable alteration of the feedback control setup for the next shot. The simulators have been used routinely in 2012 plasma campaign, and the experimental performances of the axisymmetric shape control algorithm are enhanced. Quality of the real-time EFIT has been enhanced by utilizations of the open-loop type. Using the closed-loop type, the decoupling scheme of the plasma current control and axisymmetric shape controls are verified through both the simulations and experiments. By combining with the relay feedback tuning algorithm, the improved controls helped to maintain the shape suitable for longer H-mode (10–16 s) with the number of required commissioning shots largely reduced.

  20. Using screen-based simulation of inhaled anaesthetic delivery to improve patient care.

    Science.gov (United States)

    Philip, J H

    2015-12-01

    Screen-based simulation can improve patient care by giving novices and experienced clinicians insight into drug behaviour. Gas Man(®) is a screen-based simulation program that depicts pictorially and graphically the anaesthetic gas and vapour tension from the vaporizer to the site of action, namely the brain and spinal cord. The gases and vapours depicted are desflurane, enflurane, ether, halothane, isoflurane, nitrogen, nitrous oxide, sevoflurane, and xenon. Multiple agents can be administered simultaneously or individually and the results shown on an overlay graph. Practice exercises provide in-depth knowledge of the subject matter. Experienced clinicians can simulate anaesthesia occurrences and practices for application to their clinical practice, and publish the results to benefit others to improve patient care. Published studies using this screen-based simulation have led to a number of findings, as follows: changing from isoflurane to desflurane toward the end of anaesthesia does not accelerate recovery in humans; vital capacity induction can produce loss of consciousness in 45 s; simulated context-sensitive decrement times explain recovery profiles; hyperventilation does not dramatically speed emergence; high fresh gas flow is wasteful; fresh gas flow and not the vaporizer setting should be reduced during intubation; re-anaesthetization can occur with severe hypoventilation after extubation; and in re-anaesthetization, the anaesthetic redistributes from skeletal muscle. Researchers using screen-based simulations can study fewer subjects to reach valid conclusions that impact clinical care. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. A New Improved and Extended Version of the Multicell Bacterial Simulator gro.

    Science.gov (United States)

    Gutiérrez, Martín; Gregorio-Godoy, Paula; Pérez Del Pulgar, Guillermo; Muñoz, Luis E; Sáez, Sandra; Rodríguez-Patón, Alfonso

    2017-08-18

    gro is a cell programming language developed in Klavins Lab for simulating colony growth and cell-cell communication. It is used as a synthetic biology prototyping tool for simulating multicellular biocircuits and microbial consortia. In this work, we present several extensions made to gro that improve the performance of the simulator, make it easier to use, and provide new functionalities. The new version of gro is between 1 and 2 orders of magnitude faster than the original version. It is able to grow microbial colonies with up to 10 5 cells in less than 10 min. A new library, CellEngine, accelerates the resolution of spatial physical interactions between growing and dividing cells by implementing a new shoving algorithm. A genetic library, CellPro, based on Probabilistic Timed Automata, simulates gene expression dynamics using simplified and easy to compute digital proteins. We also propose a more convenient language specification layer, ProSpec, based on the idea that proteins drive cell behavior. CellNutrient, another library, implements Monod-based growth and nutrient uptake functionalities. The intercellular signaling management was improved and extended in a library called CellSignals. Finally, bacterial conjugation, another local cell-cell communication process, was added to the simulator. To show the versatility and potential outreach of this version of gro, we provide studies and novel examples ranging from synthetic biology to evolutionary microbiology. We believe that the upgrades implemented for gro have made it into a powerful and fast prototyping tool capable of simulating a large variety of systems and synthetic biology designs.

  2. Simulating hemispatial neglect with virtual reality.

    Science.gov (United States)

    Baheux, Kenji; Yoshizawa, Makoto; Yoshida, Yasuko

    2007-07-19

    Hemispatial neglect is a cognitive disorder defined as a lack of attention for stimuli contra-lateral to the brain lesion. The assessment is traditionally done with basic pencil and paper tests and the rehabilitation programs are generally not well adapted. We propose a virtual reality system featuring an eye-tracking device for a better characterization of the neglect that will lead to new rehabilitation techniques. This paper presents a comparison of eye-gaze patterns of healthy subjects, patients and healthy simulated patients on a virtual line bisection test. The task was also executed with a reduced visual field condition hoping that fewer stimuli would limit the neglect. We found that patients and healthy simulated patients had similar eye-gaze patterns. However, while the reduced visual field condition had no effect on the healthy simulated patients, it actually had a negative impact on the patients. We discuss the reasons for these differences and how they relate to the limitations of the neglect simulation. We argue that with some improvements the technique could be used to determine the potential of new rehabilitation techniques and also help the rehabilitation staff or the patient's relatives to better understand the neglect condition.

  3. Modeling and simulation of PEM fuel cell's flow channels using CFD techniques

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Edgar F.; Andrade, Alexandre B.; Robalinho, Eric; Bejarano, Martha L.M.; Linardi, Marcelo [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: efcunha@ipen.br; abodart@ipen.br; eric@ipen.br; mmora@ipen.br; mlinardi@ipen.br; Cekinski, Efraim [Instituto de Pesquisas Tecnologicas (IPT-SP), Sao Paulo, SP (Brazil)]. E-mail: cekinski@ipt.br

    2007-07-01

    Fuel cells are one of the most important devices to obtain electrical energy from hydrogen. The Proton Exchange Membrane Fuel Cell (PEMFC) consists of two important parts: the Membrane Electrode Assembly (MEA), where the reactions occur, and the flow field plates. The plates have many functions in a fuel cell: distribute reactant gases (hydrogen and air or oxygen), conduct electrical current, remove heat and water from the electrodes and make the cell robust. The cost of the bipolar plates corresponds up to 45% of the total stack costs. The Computational Fluid Dynamic (CFD) is a very useful tool to simulate hydrogen and oxygen gases flow channels, to reduce the costs of bipolar plates production and to optimize mass transport. Two types of flow channels were studied. The first type was a commercial plate by ELECTROCELL and the other was entirely projected at Programa de Celula a Combustivel (IPEN/CNEN-SP) and the experimental data were compared with modelling results. Optimum values for each set of variables were obtained and the models verification was carried out in order to show the feasibility of this technique to improve fuel cell efficiency. (author)

  4. An agent-based simulation combined with group decision-making technique for improving the performance of an emergency department

    Directory of Open Access Journals (Sweden)

    M. Yousefi

    Full Text Available This study presents an agent-based simulation modeling in an emergency department. In a traditional approach, a supervisor (or a manager allocates the resources (receptionist, nurses, doctors, etc. to different sections based on personal experience or by using decision-support tools. In this study, each staff agent took part in the process of allocating resources based on their observation in their respective sections, which gave the system the advantage of utilizing all the available human resources during the workday by being allocated to a different section. In this simulation, unlike previous studies, all staff agents took part in the decision-making process to re-allocate the resources in the emergency department. The simulation modeled the behavior of patients, receptionists, triage nurses, emergency room nurses and doctors. Patients were able to decide whether to stay in the system or leave the department at any stage of treatment. In order to evaluate the performance of this approach, 6 different scenarios were introduced. In each scenario, various key performance indicators were investigated before and after applying the group decision-making. The outputs of each simulation were number of deaths, number of patients who leave the emergency department without being attended, length of stay, waiting time and total number of discharged patients from the emergency department. Applying the self-organizing approach in the simulation showed an average of 12.7 and 14.4% decrease in total waiting time and number of patients who left without being seen, respectively. The results showed an average increase of 11.5% in total number of discharged patients from emergency department.

  5. Developed hydraulic simulation model for water pipeline networks

    Directory of Open Access Journals (Sweden)

    A. Ayad

    2013-03-01

    Full Text Available A numerical method that uses linear graph theory is presented for both steady state, and extended period simulation in a pipe network including its hydraulic components (pumps, valves, junctions, etc.. The developed model is based on the Extended Linear Graph Theory (ELGT technique. This technique is modified to include new network components such as flow control valves and tanks. The technique also expanded for extended period simulation (EPS. A newly modified method for the calculation of updated flows improving the convergence rate is being introduced. Both benchmarks, ad Actual networks are analyzed to check the reliability of the proposed method. The results reveal the finer performance of the proposed method.

  6. Techniques for Improving Cash Management.

    Science.gov (United States)

    Lykins, Ronald G.

    1973-01-01

    This article deals with several techniques for regulating cash inflow and outflow and investing surplus cash for short periods of time. The techniques are: (1) consolidating checking accounts, (2) determining surplus cash by examining bank balances in conjunction with the cash book, (3) selecting a minimum bank balance, (4) investing a greater…

  7. Features improvement techniques supply of highly skilled bodybuilders in transition training

    Directory of Open Access Journals (Sweden)

    Oleksandr Aghyppo

    2015-03-01

    Full Text Available Purpose of this paper is to improve the supply of highly skilled technique bodybuilders training in a transition period with the restoration of lean body mass and functional state of an athlete after a competitive activity. Material and Method: the study involved 18 highly skilled bodybuilders are included in the team of the Kharkiv region of Ukraine and bodybuilding. Results: a comparative characteristic of the conventional technique that is often used in the training process in bodybuilding. Developed and justified the optimal technique for highly skilled bodybuilders, depending on the initial form of the athlete at the beginning of the transition period of training. Conclusions: on the basis of the study the author suggests best practices in supply depending on the microcycle training in transition training.

  8. A simulation technique for 3D MR-guided acoustic radiation force imaging

    International Nuclear Information System (INIS)

    Payne, Allison; Bever, Josh de; Farrer, Alexis; Coats, Brittany; Parker, Dennis L.; Christensen, Douglas A.

    2015-01-01

    Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation force field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green’s function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green’s function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028–0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison

  9. Nuclear-derived techniques improve cattle productivity and milk quality in Cameroon

    International Nuclear Information System (INIS)

    Dixit, Aabha

    2016-01-01

    Increasing agricultural production and improving the quality of milk and meat are key to combating poverty and increasing food security in Africa. Countries such as Cameroon are increasingly turning to innovative, nuclear and nuclear-derived techniques to control and prevent diseases among livestock, and boost cattle and milk production.

  10. A Simulation Model for Machine Efficiency Improvement Using Reliability Centered Maintenance: Case Study of Semiconductor Factory

    Directory of Open Access Journals (Sweden)

    Srisawat Supsomboon

    2014-01-01

    Full Text Available The purpose of this study was to increase the quality of product by focusing on the machine efficiency improvement. The principle of the reliability centered maintenance (RCM was applied to increase the machine reliability. The objective was to create preventive maintenance plan under reliability centered maintenance method and to reduce defects. The study target was set to reduce the Lead PPM for a test machine by simulating the proposed preventive maintenance plan. The simulation optimization approach based on evolutionary algorithms was employed for the preventive maintenance technique selection process to select the PM interval that gave the best total cost and Lead PPM values. The research methodology includes procedures such as following the priority of critical components in test machine, analyzing the damage and risk level by using Failure Mode and Effects Analysis (FMEA, calculating the suitable replacement period through reliability estimation, and optimizing the preventive maintenance plan. From the result of the study it is shown that the Lead PPM of test machine can be reduced. The cost of preventive maintenance, cost of good product, and cost of lost product were decreased.

  11. IMPROVING MEDICAL EDUCATION: SIMULATING CHANGES IN PATIENT ANATOMY USING DYNAMIC HAPTIC FEEDBACK.

    Science.gov (United States)

    Yovanoff, Mary; Pepley, David; Mirkin, Katelin; Moore, Jason; Han, David; Miller, Scarlett

    2016-09-01

    Virtual simulation is an emerging field in medical education. Research suggests that simulation reduces complication rates and improves learning gains for medical residents. One benefit of simulators is their allowance for more realistic and dynamic patient anatomies. While potentially useful throughout medical education, few studies have explored the impact of dynamic haptic simulators on medical training. In light of this research void, this study was developed to examine how a Dynamic-Haptic Robotic Trainer (DHRT) impacts medical student self-efficacy and skill gains compared to traditional simulators developed to train students in Internal Jugular Central Venous Catheter (IJ CVC) placement. The study was conducted with 18 third year medical students with no prior CVC insertion experience who underwent a pre-test, simulator training (manikin, robotic, or mixed) and post-test. The results revealed the DHRT as a useful method for training CVC skills and supports further research on dynamic haptic trainers in medical education.

  12. Supply chain simulation tools and techniques: a survey

    NARCIS (Netherlands)

    Kleijnen, J.P.C.

    2005-01-01

    The main contribution of this paper is twofold: it surveys different types of simulation for supply chain management; it discusses several methodological issues. These different types of simulation are spreadsheet simulation, system dynamics, discrete-event simulation and business games. Which

  13. Realization of process improvement at a diagnostic radiology department with aid of simulation modeling.

    Science.gov (United States)

    Oh, Hong-Choon; Toh, Hong-Guan; Giap Cheong, Eddy Seng

    2011-11-01

    Using the classical process improvement framework of Plan-Do-Study-Act (PDSA), the diagnostic radiology department of a tertiary hospital identified several patient cycle time reduction strategies. Experimentation of these strategies (which included procurement of new machines, hiring of new staff, redesign of queue system, etc.) through pilot scale implementation was impractical because it might incur substantial expenditure or be operationally disruptive. With this in mind, simulation modeling was used to test these strategies via performance of "what if" analyses. Using the output generated by the simulation model, the team was able to identify a cost-free cycle time reduction strategy, which subsequently led to a reduction of patient cycle time and achievement of a management-defined performance target. As healthcare professionals work continually to improve healthcare operational efficiency in response to rising healthcare costs and patient expectation, simulation modeling offers an effective scientific framework that can complement established process improvement framework like PDSA to realize healthcare process enhancement. © 2011 National Association for Healthcare Quality.

  14. A rule based method for context sensitive threshold segmentation in SPECT using simulation

    International Nuclear Information System (INIS)

    Fleming, John S.; Alaamer, Abdulaziz S.

    1998-01-01

    Robust techniques for automatic or semi-automatic segmentation of objects in single photon emission computed tomography (SPECT) are still the subject of development. This paper describes a threshold based method which uses empirical rules derived from analysis of computer simulated images of a large number of objects. The use of simulation allowed the factors affecting the threshold which correctly segmented objects to be investigated systematically. Rules could then be derived from these data to define the threshold in any particular context. The technique operated iteratively and calculated local context sensitive thresholds along radial profiles from the centre of gravity of the object. It was evaluated in a further series of simulated objects and in human studies, and compared to the use of a global fixed threshold. The method was capable of improving accuracy of segmentation and volume assessment compared to the global threshold technique. The improvements were greater for small volumes, shapes with large surface area to volume ratio, variable surrounding activity and non-uniform distributions. The method was applied successfully to simulated objects and human studies and is considered to be a significant advance on global fixed threshold techniques. (author)

  15. Improving precipitation simulation from updated surface characteristics in South America

    Science.gov (United States)

    Pereira, Gabriel; Silva, Maria Elisa Siqueira; Moraes, Elisabete Caria; Chiquetto, Júlio Barboza; da Silva Cardozo, Francielle

    2017-07-01

    Land use and land cover maps and their physical-chemical and biological properties are important variables in the numerical modeling of Earth systems. In this context, the main objective of this study is to analyze the improvements resulting from the land use and land cover map update in numerical simulations performed using the Regional Climate Model system version 4 (RegCM4), as well as the seasonal variations of physical parameters used by the Biosphere Atmosphere Transfer Scheme (BATS). In general, the update of the South America 2007 land use and land cover map, used by the BATS, improved the simulation of precipitation by 10 %, increasing the mean temporal correlation coefficient, compared to observed data, from 0.84 to 0.92 (significant at p Atlantic convergence zone (SACZ) positioning, presenting a spatial pattern of alternated areas with higher and lower precipitation rates. These important differences occur due to the replacement of tropical rainforest for pasture and agriculture and the replacement of agricultural areas for pasture, scrubland, and deciduous forest.

  16. Improved simulation of Antarctic sea ice due to the radiative effects of falling snow

    Science.gov (United States)

    Li, J.-L. F.; Richardson, Mark; Hong, Yulan; Lee, Wei-Liang; Wang, Yi-Hui; Yu, Jia-Yuh; Fetzer, Eric; Stephens, Graeme; Liu, Yinghui

    2017-08-01

    Southern Ocean sea-ice cover exerts critical control on local albedo and Antarctic precipitation, but simulated Antarctic sea-ice concentration commonly disagrees with observations. Here we show that the radiative effects of precipitating ice (falling snow) contribute substantially to this discrepancy. Many models exclude these radiative effects, so they underestimate both shortwave albedo and downward longwave radiation. Using two simulations with the climate model CESM1, we show that including falling-snow radiative effects improves the simulations relative to cloud properties from CloudSat-CALIPSO, radiation from CERES-EBAF and sea-ice concentration from passive microwave sensors. From 50-70°S, the simulated sea-ice-area bias is reduced by 2.12 × 106 km2 (55%) in winter and by 1.17 × 106 km2 (39%) in summer, mainly because increased wintertime longwave heating restricts sea-ice growth and so reduces summer albedo. Improved Antarctic sea-ice simulations will increase confidence in projected Antarctic sea level contributions and changes in global warming driven by long-term changes in Southern Ocean feedbacks.

  17. FEM Techniques for High Stress Detection in Accelerated Fatigue Simulation

    Science.gov (United States)

    Veltri, M.

    2016-09-01

    This work presents the theory and a numerical validation study in support to a novel method for a priori identification of fatigue critical regions, with the aim to accelerate durability design in large FEM problems. The investigation is placed in the context of modern full-body structural durability analysis, where a computationally intensive dynamic solution could be required to identify areas with potential for fatigue damage initiation. The early detection of fatigue critical areas can drive a simplification of the problem size, leading to sensible improvement in solution time and model handling while allowing processing of the critical areas in higher detail. The proposed technique is applied to a real life industrial case in a comparative assessment with established practices. Synthetic damage prediction quantification and visualization techniques allow for a quick and efficient comparison between methods, outlining potential application benefits and boundaries.

  18. Scalable Simulation of Electromagnetic Hybrid Codes

    International Nuclear Information System (INIS)

    Perumalla, Kalyan S.; Fujimoto, Richard; Karimabadi, Dr. Homa

    2006-01-01

    New discrete-event formulations of physics simulation models are emerging that can outperform models based on traditional time-stepped techniques. Detailed simulation of the Earth's magnetosphere, for example, requires execution of sub-models that are at widely differing timescales. In contrast to time-stepped simulation which requires tightly coupled updates to entire system state at regular time intervals, the new discrete event simulation (DES) approaches help evolve the states of sub-models on relatively independent timescales. However, parallel execution of DES-based models raises challenges with respect to their scalability and performance. One of the key challenges is to improve the computation granularity to offset synchronization and communication overheads within and across processors. Our previous work was limited in scalability and runtime performance due to the parallelization challenges. Here we report on optimizations we performed on DES-based plasma simulation models to improve parallel performance. The net result is the capability to simulate hybrid particle-in-cell (PIC) models with over 2 billion ion particles using 512 processors on supercomputing platforms

  19. Improved cloud parameterization for Arctic climate simulations based on satellite data

    Science.gov (United States)

    Klaus, Daniel; Dethloff, Klaus; Dorn, Wolfgang; Rinke, Annette

    2015-04-01

    The defective representation of Arctic cloud processes and properties remains a crucial problem in climate modelling and in reanalysis products. Satellite-based cloud observations (MODIS and CPR/CALIOP) and single-column model simulations (HIRHAM5-SCM) were exploited to evaluate and improve the simulated Arctic cloud cover of the atmospheric regional climate model HIRHAM5. The ECMWF reanalysis dataset 'ERA-Interim' (ERAint) was used for the model initialization, the lateral boundary forcing as well as the dynamical relaxation inside the pan-Arctic domain. HIRHAM5 has a horizontal resolution of 0.25° and uses 40 pressure-based and terrain-following vertical levels. In comparison with the satellite observations, the HIRHAM5 control run (HH5ctrl) systematically overestimates total cloud cover, but to a lesser extent than ERAint. The underestimation of high- and mid-level clouds is strongly outweighed by the overestimation of low-level clouds. Numerous sensitivity studies with HIRHAM5-SCM suggest (1) the parameter tuning, enabling a more efficient Bergeron-Findeisen process, combined with (2) an extension of the prognostic-statistical (PS) cloud scheme, enabling the use of negatively skewed beta distributions. This improved model setup was then used in a corresponding HIRHAM5 sensitivity run (HH5sens). While the simulated high- and mid-level cloud cover is improved only to a limited extent, the large overestimation of low-level clouds can be systematically and significantly reduced, especially over sea ice. Consequently, the multi-year annual mean area average of total cloud cover with respect to sea ice is almost 14% lower than in HH5ctrl. Overall, HH5sens slightly underestimates the observed total cloud cover but shows a halved multi-year annual mean bias of 2.2% relative to CPR/CALIOP at all latitudes north of 60° N. Importantly, HH5sens produces a more realistic ratio between the cloud water and ice content. The considerably improved cloud simulation manifests in

  20. Research on digital multi-channel pulse height analysis techniques

    International Nuclear Information System (INIS)

    Xiao Wuyun; Wei Yixiang; Ai Xianyun; Ao Qi

    2005-01-01

    Multi-channel pulse height analysis techniques are developing in the direction of digitalization. Based on digital signal processing techniques, digital multi-channel analyzers are characterized by powerful pulse processing ability, high throughput, improved stability and flexibility. This paper analyzes key techniques of digital nuclear pulse processing. With MATLAB software, main algorithms are simulated, such as trapezoidal shaping, digital baseline estimation, digital pole-zero/zero-pole compensation, poles and zeros identification. The preliminary general scheme of digital MCA is discussed, as well as some other important techniques about its engineering design. All these lay the foundation of developing homemade digital nuclear spectrometers. (authors)

  1. A Novel Idea for Optimizing Condition-Based Maintenance Using Genetic Algorithms and Continuous Event Simulation Techniques

    Directory of Open Access Journals (Sweden)

    Mansoor Ahmed Siddiqui

    2017-01-01

    Full Text Available Effective maintenance strategies are of utmost significance for system engineering due to their direct linkage with financial aspects and safety of the plants’ operation. At a point where the state of a system, for instance, level of its deterioration, can be constantly observed, a strategy based on condition-based maintenance (CBM may be affected; wherein upkeep of the system is done progressively on the premise of monitored state of the system. In this article, a multicomponent framework is considered that is continuously kept under observation. In order to decide an optimal deterioration stage for the said system, Genetic Algorithm (GA technique has been utilized that figures out when its preventive maintenance should be carried out. The system is configured into a multiobjective problem that is aimed at optimizing the two desired objectives, namely, profitability and accessibility. For the sake of reality, a prognostic model portraying the advancements of deteriorating system has been employed that will be based on utilization of continuous event simulation techniques. In this regard, Monte Carlo (MC simulation has been shortlisted as it can take into account a wide range of probable options that can help in reducing uncertainty. The inherent benefits proffered by the said simulation technique are fully utilized to display various elements of a deteriorating system working under stressed environment. The proposed synergic model (GA and MC is considered to be more effective due to the employment of “drop-by-drop approach” that permits successful drive of the related search process with regard to the best optimal solutions.

  2. Modified Dual Three-Pulse Modulation technique for single-phase inverter topology

    Science.gov (United States)

    Sree Harsha, N. R.; Anitha, G. S.; Sreedevi, A.

    2016-01-01

    In a recent paper, a new modulation technique called Dual Three Pulse Modulation (DTPM) was proposed to improve the efficiency of the power converters of the Electric/Hybrid/Fuel-cell vehicles. It was simulated in PSIM 9.0.4 and uses analog multiplexers to generate the modulating signals for the DC/DC converter and inverter. The circuit used is complex and many other simulation softwares do not support the analog multiplexers as well. Also, the DTPM technique produces modulating signals for the converter, which are essentially needed to produce the modulating signals for the inverter. Hence, it cannot be used efficiently to switch the valves of a stand-alone inverter. We propose a new method to generate the modulating signals to switch MOSFETs of a single phase Dual-Three pulse Modulation based stand-alone inverter. The circuits proposed are simulated in Multisim 12.0. We also show an alternate way to switch a DC/DC converter in a way depicted by DTPM technique both in simulation (MATLAB/Simulink) and hardware. The circuitry is relatively simple and can be used for the further investigations of DTPM technique.

  3. Improving image quality of parallel phase-shifting digital holography

    International Nuclear Information System (INIS)

    Awatsuji, Yasuhiro; Tahara, Tatsuki; Kaneko, Atsushi; Koyama, Takamasa; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2008-01-01

    The authors propose parallel two-step phase-shifting digital holography to improve the image quality of parallel phase-shifting digital holography. The proposed technique can increase the effective number of pixels of hologram twice in comparison to the conventional parallel four-step technique. The increase of the number of pixels makes it possible to improve the image quality of the reconstructed image of the parallel phase-shifting digital holography. Numerical simulation and preliminary experiment of the proposed technique were conducted and the effectiveness of the technique was confirmed. The proposed technique is more practical than the conventional parallel phase-shifting digital holography, because the composition of the digital holographic system based on the proposed technique is simpler.

  4. Technique for Simulation of Black Sea Circulation with Increased Resolution in the Area of the IO RAS Polygon

    Science.gov (United States)

    Gusev, A. V.; Zalesny, V. B.; Fomin, V. V.

    2017-11-01

    A numerical technique is presented for simulating the hydrophysical fields of the Black Sea on a variable-step grid with refinement in the area of IO RAS polygon. Model primitive equations are written in spherical coordinates with an arbitrary arrangement of poles. In order to increase the horizontal resolution of the coastal zone in the area of the IO RAS polygon in the northeastern part of the sea near Gelendzhik, one of the poles is placed at a land point (38.35° E, 44.75° N). The model horizontal resolution varies from 150 m in the area of the IO RAS polygon to 4.6 km in the southwestern part of the Black Sea. The numerical technique makes it possible to simulate a large-scale structure of Black Sea circulation as well as the meso- and submesoscale dynamics of the coastal zone. In order to compute the atmospheric forcing, the results of the regional climate model WRF with a resolution of about 10 km in space and 1 h in time are used. In order to demonstrate the technique, Black Sea hydrophysical fields for 2011-2012 and a passive tracer transport representing self-cleaning of Gelendzhik Bay in July 2012 are simulated.

  5. Faster quantum chemistry simulation on fault-tolerant quantum computers

    International Nuclear Information System (INIS)

    Cody Jones, N; McMahon, Peter L; Yamamoto, Yoshihisa; Whitfield, James D; Yung, Man-Hong; Aspuru-Guzik, Alán; Van Meter, Rodney

    2012-01-01

    Quantum computers can in principle simulate quantum physics exponentially faster than their classical counterparts, but some technical hurdles remain. We propose methods which substantially improve the performance of a particular form of simulation, ab initio quantum chemistry, on fault-tolerant quantum computers; these methods generalize readily to other quantum simulation problems. Quantum teleportation plays a key role in these improvements and is used extensively as a computing resource. To improve execution time, we examine techniques for constructing arbitrary gates which perform substantially faster than circuits based on the conventional Solovay–Kitaev algorithm (Dawson and Nielsen 2006 Quantum Inform. Comput. 6 81). For a given approximation error ϵ, arbitrary single-qubit gates can be produced fault-tolerantly and using a restricted set of gates in time which is O(log ϵ) or O(log log ϵ); with sufficient parallel preparation of ancillas, constant average depth is possible using a method we call programmable ancilla rotations. Moreover, we construct and analyze efficient implementations of first- and second-quantized simulation algorithms using the fault-tolerant arbitrary gates and other techniques, such as implementing various subroutines in constant time. A specific example we analyze is the ground-state energy calculation for lithium hydride. (paper)

  6. Inverse simulated annealing: Improvements and application to amorphous InSb

    OpenAIRE

    Los, Jan H.; Gabardi, Silvia; Bernasconi, Marco; Kühne, Thomas D.

    2014-01-01

    An improved inverse simulated annealing method is presented to determine the structure of complex disordered systems from first principles in agreement with available experimental data or desired predetermined target properties. The effectiveness of this method is demonstrated by revisiting the structure of amorphous InSb. The resulting network is mostly tetrahedral and in excellent agreement with available experimental data.

  7. Improving advanced cardiovascular life support skills in medical students: simulation-based education approach

    Directory of Open Access Journals (Sweden)

    Hamidreza Reihani

    2015-01-01

    Full Text Available Objective: In this trial, we intend to assess the effect of simulation-based education approach on advanced cardiovascular life support skills among medical students. Methods: Through convenient sampling method, 40 interns of Mashhad University of Medical Sciences in their emergency medicine rotation (from September to December 2012 participated in this study. Advanced Cardiovascular Life Support (ACLS workshops with pretest and post-test exams were performed. Workshops and checklists for pretest and post-test exams were designed according to the latest American Heart Association (AHA guidelines. Results: The total score of the students increased significantly after workshops (24.6 out of 100 to 78.6 out of 100. This demonstrates 53.9% improvement in the skills after the simulation-based education (P< 0.001. Also the mean score of each station had a significant improvement (P< 0.001. Conclusion: Pretests showed that interns had poor performance in practical clinical matters while their scientific knowledge, such as ECG interpretation was acceptable. The overall results of the study highlights that Simulation based-education approach is highly effective in Improving ACLS skills among medical students.

  8. Manufacturing plant performance evaluation by discrete event simulation

    International Nuclear Information System (INIS)

    Rosli Darmawan; Mohd Rasid Osman; Rosnah Mohd Yusuff; Napsiah Ismail; Zulkiflie Leman

    2002-01-01

    A case study was conducted to evaluate the performance of a manufacturing plant using discrete event simulation technique. The study was carried out on animal feed production plant. Sterifeed plant at Malaysian Institute for Nuclear Technology Research (MINT), Selangor, Malaysia. The plant was modelled base on the actual manufacturing activities recorded by the operators. The simulation was carried out using a discrete event simulation software. The model was validated by comparing the simulation results with the actual operational data of the plant. The simulation results show some weaknesses with the current plant design and proposals were made to improve the plant performance. (Author)

  9. Development, improvement and calibration of neutronic reaction rates measurements: elaboration of a standard techniques basis

    International Nuclear Information System (INIS)

    Hudelot, J.P.

    1998-06-01

    In order to improve and to validate the neutronics calculation schemes, perfecting integral measurements of neutronics parameters is necessary. This thesis focuses on the conception, the improvement and the development of neutronics reaction rates measurements, and aims at building a base of standard techniques. Two subjects are discussed. The first one deals with direct measurements by fission chambers. A short presentation of the different usual techniques is given. Then, those last ones are applied through the example of doubling time measurements on the EOLE facility during the MISTRAL 1 experimental programme. Two calibration devices of fission chambers are developed: a thermal column located in the central part of the MINERVE facility, and a calibration cell using a pulsed high flux neutron generator and based on the discrimination of the energy of the neutrons with a time-of-flight method. This second device will soon allow to measure the mass of fission chambers with a precision of about 1 %. Finally, the necessity of those calibrations will be shown through spectral indices measurements in core MISTRAL 1 (UO 2 ) and MISTRAL 2 (MOX) of the EOLE facility. In each case, the associated calculation schemes, performed using the Monte Carlo MCNP code with the ENDF-BV library, will be validated. Concerning the second one, the goal is to develop a method for measuring the modified conversion ratio of 238 U (defined as the ratio of 238 U capture rate to total fission rate) by gamma-ray spectrometry of fuel rods. Within the framework of the MISTRAL 1 and MISTRAL 2 programmes, the measurement device, the experimental results and the spectrometer calibration are described. Furthermore, the MCNP calculations of neutron self-shielding and gamma self-absorption are validated. It is finally shown that measurement uncertainties are better than 1 %. The extension of this technique to future modified conversion ratio measurements for 242 Pu (on MOX rods) and 232 Th (on

  10. Improved nondominant hand performance on a laparoscopic virtual reality simulator after playing the Nintendo Wii.

    Science.gov (United States)

    Middleton, Kellie K; Hamilton, Travis; Tsai, Pei-Chien; Middleton, Dana B; Falcone, John L; Hamad, Giselle

    2013-11-01

    Video games have been shown to improve eye-hand coordination, spatial visualization, manual dexterity, and rapid mental processing, which are important in the acquisition of laparoscopic skills. This study investigated the relationship between playing Nintendo(®) Wii™ and virtual reality (VR) laparoscopic surgery simulator performance. We hypothesized that playing the Wii would improve surgical skills performance on a VR laparoscopic simulator and hoped to elucidate which tasks, in particular, would be most beneficial for nondominant hand training. This was a single-blinded, randomized, prospective study conducted with 23 student volunteers. VR laparoscopic skills were assessed at baseline on a Simbionix LapMentor™ Surgical Simulator (Simbionix Ltd., Israel) and after the gaming period of 2 weeks. Simulator performance metrics were compared between groups using nonparametric statistics and an alpha of 0.05. Compared with the control group, the Wii-playing group demonstrated greater improvement of six measures, including accuracy on the eye-hand coordination task (p = 0.04), faster completion time (p = 0.04), decreased number of left-handed movements (p = 0.03), decreased left handed total path length (p = 0.03), decreased total number of grasping attempts (p = 0.04), and improved left-handed economy of movement (p = 0.05) for the bimanual clipping and grasping task. When comparing the number of measures improved upon by the Wii-playing group and the control group for all three tasks, the Wii-playing group consistently outperformed the control group in 18 measures compared with the control group's improvement in 6. This study further characterizes the association between video game playing and surgical performance. Improvements following the intervention were made in the most basic of surgical skills, most notably with the nondominant hand, suggesting that short-term playing of the Wii could improve bimanual dexterity and expedite the acquisition of basic

  11. Improved simulation of peak flows under climate change: post-processing or composite opjective calibration?

    NARCIS (Netherlands)

    Zhang, Xujie; Booij, Martijn J.; Xu, YuePing

    2015-01-01

    Climate change is expected to have large impacts on peak flows. However, there may be bias in the simulation of peak flows by hydrological models. This study aims to improve the simulation of peak flows under climate change in Lanjiang catchment, east China, by comparing two approaches:

  12. Simulating GPS radio signal to synchronize network--a new technique for redundant timing.

    Science.gov (United States)

    Shan, Qingxiao; Jun, Yang; Le Floch, Jean-Michel; Fan, Yaohui; Ivanov, Eugene N; Tobar, Michael E

    2014-07-01

    Currently, many distributed systems such as 3G mobile communications and power systems are time synchronized with a Global Positioning System (GPS) signal. If there is a GPS failure, it is difficult to realize redundant timing, and thus time-synchronized devices may fail. In this work, we develop time transfer by simulating GPS signals, which promises no extra modification to original GPS-synchronized devices. This is achieved by applying a simplified GPS simulator for synchronization purposes only. Navigation data are calculated based on a pre-assigned time at a fixed position. Pseudo-range data which describes the distance change between the space vehicle (SV) and users are calculated. Because real-time simulation requires heavy-duty computations, we use self-developed software optimized on a PC to generate data, and save the data onto memory disks while the simulator is operating. The radio signal generation is similar to the SV at an initial position, and the frequency synthesis of the simulator is locked to a pre-assigned time. A filtering group technique is used to simulate the signal transmission delay corresponding to the SV displacement. Each SV generates a digital baseband signal, where a unique identifying code is added to the signal and up-converted to generate the output radio signal at the centered frequency of 1575.42 MHz (L1 band). A prototype with a field-programmable gate array (FPGA) has been built and experiments have been conducted to prove that we can realize time transfer. The prototype has been applied to the CDMA network for a three-month long experiment. Its precision has been verified and can meet the requirements of most telecommunication systems.

  13. Survival of the Fittest: An Active Queue Management Technique for Noisy Packet Flows

    Directory of Open Access Journals (Sweden)

    Shirish S. Karande

    2007-01-01

    Full Text Available We present a novel active queue management (AQM technique to demonstrate the efficacy of practically harnessing the predictive utility of SSR indications for improved video communication. We consider a network within which corrupted packets are relayed over multiple hops, but a certain percentage of packets needs to be dropped at an intermediate node due to congestion. We propose an AQM technique, survival of the fittest (SOTF, to be employed at the relay node, within which we use packet state information, available from SSR indications and checksums, to drop packets with the highest corruption levels. On the basis of actual 802.11b measurements we show that such a side information (SI aware processing within the network can provide significant performance benefits over an SI-unaware scheme, random queue management (RQM, which is forced to randomly discard packets. With trace-based simulations, we show the utility of the proposed AQM technique in improving the error recovery performance of cross-layer FEC schemes. Finally, with the help of H.264-based video simulations these improvements are shown to translate into a significant improvement in video quality.

  14. Accelerating transient simulation of linear reduced order models.

    Energy Technology Data Exchange (ETDEWEB)

    Thornquist, Heidi K.; Mei, Ting; Keiter, Eric Richard; Bond, Brad

    2011-10-01

    Model order reduction (MOR) techniques have been used to facilitate the analysis of dynamical systems for many years. Although existing model reduction techniques are capable of providing huge speedups in the frequency domain analysis (i.e. AC response) of linear systems, such speedups are often not obtained when performing transient analysis on the systems, particularly when coupled with other circuit components. Reduced system size, which is the ostensible goal of MOR methods, is often insufficient to improve transient simulation speed on realistic circuit problems. It can be shown that making the correct reduced order model (ROM) implementation choices is crucial to the practical application of MOR methods. In this report we investigate methods for accelerating the simulation of circuits containing ROM blocks using the circuit simulator Xyce.

  15. Nonperturbative QCD simulations with 2+1 flavors of improved staggered quarks

    International Nuclear Information System (INIS)

    Bazavov, A.; Toussaint, D.; Bernard, C.; Laiho, J.; DeTar, C.; Levkova, L.; Oktay, M. B.; Gottlieb, Steven; Heller, U. M.; Hetrick, J. E.; Mackenzie, P. B.; Sugar, R.; Van de Water, R. S.

    2010-01-01

    Dramatic progress has been made over the last decade in the numerical study of quantum chromodynamics (QCD) through the use of improved formulations of QCD on the lattice (improved actions), the development of new algorithms, and the rapid increase in computing power available to lattice gauge theorists. In this article simulations of full QCD are described using the improved staggered quark formalism, ''asqtad'' fermions. These simulations were carried out with two degenerate flavors of light quarks (up and down) and with one heavier flavor, the strange quark. Several light quark masses, down to about three times the physical light quark mass, and six lattice spacings have been used. These enable controlled continuum and chiral extrapolations of many low energy QCD observables. The improved staggered formalism is reviewed, emphasizing both advantages and drawbacks. In particular, the procedure for removing unwanted staggered species in the continuum limit is reviewed. Then the asqtad lattice ensembles created by the MILC Collaboration are described. All MILC lattice ensembles are publicly available, and they have been used extensively by a number of lattice gauge theory groups. The physics results obtained with them are reviewed, and the impact of these results on phenomenology is discussed. Topics include the heavy quark potential, spectrum of light hadrons, quark masses, decay constants of light and heavy-light pseudoscalar mesons, semileptonic form factors, nucleon structure, scattering lengths, and more.

  16. Improving Inversions of the Overlap Operator

    International Nuclear Information System (INIS)

    Krieg, S.; Cundy, N.; Eshof, J. van den; Frommer, A.; Lippert, Th.; Schaefer, K.

    2005-01-01

    We present relaxation and preconditioning techniques which accelerate the inversion of the overlap operator by a factor of four on small lattices, with larger gains as the lattice size increases. These improvements can be used in both propagator calculations and dynamical simulations

  17. Design and development of high performance solar photovoltaic inverter with advanced modulation techniques to improve power quality

    Science.gov (United States)

    Alexander Stonier, Albert

    2017-02-01

    In addition to the focus towards growing demand on electrical energy due to the increase in population, industries, consumer loads, etc., the need for improving the quality of electrical power also needs to be considered. The design and development of solar photovoltaic (PV) inverter with reduced harmonic distortions is proposed. Unlike the conventional solar PV inverters, the proposed inverter provides the advantages of reduced harmonic distortions thereby intend towards the improvement in power quality. This inverter comprises of multiple stages which provides the required 230VRMS, 50 Hz in spite of variations in solar PV due to temperature and irradiance. The reduction of harmonics is governed by applying proper switching sequences required for the inverter switches. The detailed analysis is carried out by employing different switching techniques and observing its performance. With a separate mathematical model for a solar PV, simulations are performed in MATLAB software. To show the advantage of the system proposed, a 3 kWp photovoltaic plant coupled with multilevel inverter is demonstrated in hardware. The novelty resides in the design of a single chip controller which can provide the switching sequence based on the requirement and application. As per the results obtained, the solar-fed multistage inverter improves the quality of power which makes this inverter suitable for both stand-alone and grid-connected systems.

  18. Cryoanalgesia after thoracotomy. Improvement of technique and review of 600 cases.

    Science.gov (United States)

    Maiwand, M O; Makey, A R; Rees, A

    1986-08-01

    The efficacy of cryoanalgesia for the control of post-thoracotomy pain has led to the acceptance of the technique as a routine procedure in this unit. A study of 600 consecutive patients in whom an improved technique was used is not reported. The freezing time for each intercostal nerve in this group was reduced to one 30 second exposure instead of the two 30 second exposures previously used. This reduced the duration of cutaneous numbness, with no loss of pain control. Freezing above the fifth intercostal nerve is no longer practiced in women. Modification to the probe has simplified the procedure. Pulmonary function studies and blood-gas analysis are also described.

  19. Study of Various Techniques for Improving Weak and Compressible Clay Soil under a High Earth Embankment

    Directory of Open Access Journals (Sweden)

    Zein A.K. M.

    2014-04-01

    Full Text Available This paper investigates the suitability of three soil improvement techniques for the construction of a high earth embankment on thick weak and highly compressible clay soil. The eastern approach embankment of Alhalfaya Bridge on the River Nile linking Khartoum North and Omdurman cities was chosen as a case study and a comprehensive site investigation program was carried out to determine the properties the subsurface soils. The study results showed that unless the subsurface soils have been improved they may fail or undergo excessively large settlements due to the embankment construction. Three ground improvement techniques based on the principles of the “staged construction method, SCM”, “vertical sand drain, VSD” and “sand compaction piles, SCP” of embankment foundation soil treatment are discussed and evaluated. Embankment design options based on applications of the above methods have been proposed for foundation treatment to adequately support embankment loads. A method performance evaluation based on the improvement of soil properties achieved; the time required for construction and compared estimated costs criteria was made to assess the effectiveness and expected overall performance. Adoption of any of the soil improvement techniques considered depends mainly on the most critical and decisive factor governing the embankment design. Based on the overall performance for the embankment case studied, the sand drains is considered as the most appropriate improvement method followed by the sand compaction piles technique whereas the staged construction method showed the poorest overall performance.

  20. Vectorization and improvement of nuclear codes. 3. DGR, STREAM V3.1, Cella, GGR

    Energy Technology Data Exchange (ETDEWEB)

    Nemoto, Toshiyuki; Eguchi, Norikuni; Watanabe, Hideo; Machida, Masahiko; Yokokawa, Mitsuo; Fujii, Minoru [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1995-01-01

    Four nuclear codes have been vectorized and improved in order to realize the high speed performance on the VP2600 supercomputer at Computing and Information Systems Center of JAERI in the fiscal year 1993. Molecular Dynamics simulation code DGR which simulates the irradiation damage on diamond crystalline, three-dimensional non-steady compressible fluid dynamics code STREAM V3.1, two-dimensional fluid simulation code using Cell Automaton model Cella and Molecular Dynamics code GGR which simulates the irradiation damage on black carbon crystalline have been vectorized and improved, respectively. Speed up ratios by the vectorization to scalar mode on VP2600 show 2.8, 6.8-14.8, 15-16 and 1.23 times for DGR, STREAM V3.1, Cella and GGR, respectively. In this report, we present vectorization techniques, vectorization effects, evaluations of the numerical results and techniques for the improvement. (author).

  1. 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.

  2. Simulating train movement in an urban railway based on an improved car-following model

    International Nuclear Information System (INIS)

    Ye Jing-Jing; Jin Xin-Min; Li Ke-Ping

    2013-01-01

    Based on the optimal velocity car-following model, in this paper, we propose an improved model for simulating train movement in an urban railway in which the regenerative energy of a train is considered. Here a new additional term is introduced into a traditional car-following model. Our aim is to analyze and discuss the dynamic characteristics of the train movement when the regenerative energy is utilized by the electric locomotive. The simulation results indicate that the improved car-following model is suitable for simulating the train movement. Further, some qualitative relationships between regenerative energy and dynamic characteristics of a train are investigated, such as the measurement data of regenerative energy presents a power-law distribution. Our results are useful for optimizing the design and plan of urban railway systems. (general)

  3. LEAN SIX SIGMA TECHNIQUES TO IMPROVE OPHTHALMOLOGY CLINIC EFFICIENCY.

    Science.gov (United States)

    Ciulla, Thomas A; Tatikonda, Mohan V; ElMaraghi, Yehya A; Hussain, Rehan M; Hill, Amanda L; Clary, Julie M; Hattab, Eyas

    2017-07-18

    Ophthalmologists serve an increasing volume of a growing elderly population undergoing increasingly complex outpatient medical care, including extensive diagnostic testing and treatment. The resulting prolonged patient visit times ("patient flow times") limit quality, patient and employee satisfaction, and represent waste. Lean Six Sigma process improvement was used in a vitreoretinal practice to decrease patient flow time, demonstrating that this approach can yield significant improvement in health care. Process flow maps were created to determine the most common care pathways within clinic. Three months' visits from the electronic medical record system, which tracks patient task times at each process step in the office were collected. Care tasks and care pathways consuming the greatest time and variation were identified and modified. Follow-up analysis from 6 weeks' visits was conducted to assess improvement. Nearly all patients took one of five paths through the office. Patient flow was redesigned to reduce waiting room time by having staff members immediately start patients into one of those five paths; staffing was adjusted to address high demand tasks, and scheduling was optimized around derived predictors of patient flow times. Follow-up analysis revealed a statistically significant decline in mean patient flow time by 18% and inpatient flow time SD by 4.6%. Patient and employee satisfaction scores improved. Manufacturing industry techniques, such as Lean and Six Sigma, can be used to improve patient care, minimize waste, and enhance patient and staff satisfaction in outpatient clinics.

  4. Theory, Modeling and Simulation: Research progress report 1994--1995

    Energy Technology Data Exchange (ETDEWEB)

    Garrett, B.C.; Dixon, D.A.; Dunning, T.H.

    1997-01-01

    The Pacific Northwest National Laboratory (PNNL) has established the Environmental Molecular Sciences Laboratory (EMSL). In April 1994, construction began on the new EMSL, a collaborative research facility devoted to advancing the understanding of environmental molecular science. Research in the Theory, Modeling, and Simulation (TM and S) program will play a critical role in understanding molecular processes important in restoring DOE`s research, development, and production sites, including understanding the migration and reactions of contaminants in soils and ground water, developing processes for isolation and processing of pollutants, developing improved materials for waste storage, understanding the enzymatic reactions involved in the biodegradation of contaminants, and understanding the interaction of hazardous chemicals with living organisms. The research objectives of the TM and S program are fivefold: to apply available electronic structure and dynamics techniques to study fundamental molecular processes involved in the chemistry of natural and contaminated systems; to extend current electronic structure and dynamics techniques to treat molecular systems of future importance and to develop new techniques for addressing problems that are computationally intractable at present; to apply available molecular modeling techniques to simulate molecular processes occurring in the multi-species, multi-phase systems characteristic of natural and polluted environments; to extend current molecular modeling techniques to treat ever more complex molecular systems and to improve the reliability and accuracy of such simulations; and to develop technologies for advanced parallel architectural computer systems. Research highlights of 82 projects are given.

  5. Evaluation of Advanced Signal Processing Techniques to Improve Detection and Identification of Embedded Defects

    Energy Technology Data Exchange (ETDEWEB)

    Clayton, Dwight A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Santos-Villalobos, Hector J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Baba, Justin S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-01

    By the end of 1996, 109 Nuclear Power Plants were operating in the United States, producing 22% of the Nation’s electricity [1]. At present, more than two thirds of these power plants are more than 40 years old. The purpose of the U.S. Department of Energy Office of Nuclear Energy’s Light Water Reactor Sustainability (LWRS) Program is to develop technologies and other solutions that can improve the reliability, sustain the safety, and extend the operating lifetimes of nuclear power plants (NPPs) beyond 60 years [2]. The most important safety structures in an NPP are constructed of concrete. The structures generally do not allow for destructive evaluation and access is limited to one side of the concrete element. Therefore, there is a need for techniques and technologies that can assess the internal health of complex, reinforced concrete structures nondestructively. Previously, we documented the challenges associated with Non-Destructive Evaluation (NDE) of thick, reinforced concrete sections and prioritized conceptual designs of specimens that could be fabricated to represent NPP concrete structures [3]. Consequently, a 7 feet tall, by 7 feet wide, by 3 feet and 4-inch-thick concrete specimen was constructed with 2.257-inch-and 1-inch-diameter rebar every 6 to 12 inches. In addition, defects were embedded the specimen to assess the performance of existing and future NDE techniques. The defects were designed to give a mix of realistic and controlled defects for assessment of the necessary measures needed to overcome the challenges with more heavily reinforced concrete structures. Information on the embedded defects is documented in [4]. We also documented the superiority of Frequency Banded Decomposition (FBD) Synthetic Aperture Focusing Technique (SAFT) over conventional SAFT when probing defects under deep concrete cover. Improvements include seeing an intensity corresponding to a defect that is either not visible at all in regular, full frequency content SAFT

  6. A review on computational fluid dynamic simulation techniques for Darrieus vertical axis wind turbines

    International Nuclear Information System (INIS)

    Ghasemian, Masoud; Ashrafi, Z. Najafian; Sedaghat, Ahmad

    2017-01-01

    Highlights: • A review on CFD simulation technique for Darrieus wind turbines is provided. • Recommendations and guidelines toward reliable and accurate simulations are presented. • Different progresses in CFD simulation of Darrieus wind turbines are addressed. - Abstract: The global warming threats, the presence of policies on support of renewable energies, and the desire for clean smart cities are the major drives for most recent researches on developing small wind turbines in urban environments. VAWTs (vertical axis wind turbines) are most appealing for energy harvesting in the urban environment. This is attributed due to structural simplicity, wind direction independency, no yaw mechanism required, withstand high turbulence winds, cost effectiveness, easier maintenance, and lower noise emission of VAWTs. This paper reviews recent published works on CFD (computational fluid dynamic) simulations of Darrieus VAWTs. Recommendations and guidelines are presented for turbulence modeling, spatial and temporal discretization, numerical schemes and algorithms, and computational domain size. The operating and geometrical parameters such as tip speed ratio, wind speed, solidity, blade number and blade shapes are fully investigated. The purpose is to address different progresses in simulations areas such as blade profile modification and optimization, wind turbine performance augmentation using guide vanes, wind turbine wake interaction in wind farms, wind turbine aerodynamic noise reduction, dynamic stall control, self-starting characteristics, and effects of unsteady and skewed wind conditions.

  7. Improved social force model based on exit selection for microscopic pedestrian simulation in subway station

    Institute of Scientific and Technical Information of China (English)

    郑勋; 李海鹰; 孟令云; 许心越; 陈旭

    2015-01-01

    An improved social force model based on exit selection is proposed to simulate pedestrians’ microscopic behaviors in subway station. The modification lies in considering three factors of spatial distance, occupant density and exit width. In addition, the problem of pedestrians selecting exit frequently is solved as follows: not changing to other exits in the affected area of one exit, using the probability of remaining preceding exit and invoking function of exit selection after several simulation steps. Pedestrians in subway station have some special characteristics, such as explicit destinations, different familiarities with subway station. Finally, Beijing Zoo Subway Station is taken as an example and the feasibility of the model results is verified through the comparison of the actual data and simulation data. The simulation results show that the improved model can depict the microscopic behaviors of pedestrians in subway station.

  8. Thermal measurements and inverse techniques

    CERN Document Server

    Orlande, Helcio RB; Maillet, Denis; Cotta, Renato M

    2011-01-01

    With its uncommon presentation of instructional material regarding mathematical modeling, measurements, and solution of inverse problems, Thermal Measurements and Inverse Techniques is a one-stop reference for those dealing with various aspects of heat transfer. Progress in mathematical modeling of complex industrial and environmental systems has enabled numerical simulations of most physical phenomena. In addition, recent advances in thermal instrumentation and heat transfer modeling have improved experimental procedures and indirect measurements for heat transfer research of both natural phe

  9. Simulating hemispatial neglect with virtual reality

    Directory of Open Access Journals (Sweden)

    Yoshizawa Makoto

    2007-07-01

    Full Text Available Abstract Background Hemispatial neglect is a cognitive disorder defined as a lack of attention for stimuli contra-lateral to the brain lesion. The assessment is traditionally done with basic pencil and paper tests and the rehabilitation programs are generally not well adapted. We propose a virtual reality system featuring an eye-tracking device for a better characterization of the neglect that will lead to new rehabilitation techniques. Methods This paper presents a comparison of eye-gaze patterns of healthy subjects, patients and healthy simulated patients on a virtual line bisection test. The task was also executed with a reduced visual field condition hoping that fewer stimuli would limit the neglect. Results We found that patients and healthy simulated patients had similar eye-gaze patterns. However, while the reduced visual field condition had no effect on the healthy simulated patients, it actually had a negative impact on the patients. We discuss the reasons for these differences and how they relate to the limitations of the neglect simulation. Conclusion We argue that with some improvements the technique could be used to determine the potential of new rehabilitation techniques and also help the rehabilitation staff or the patient's relatives to better understand the neglect condition.

  10. RNA interference: a promising technique for the improvement of traditional crops.

    Science.gov (United States)

    Katoch, Rajan; Thakur, Neelam

    2013-03-01

    RNA interference (RNAi) is a homology-dependent gene-silencing technology that involves double-stranded RNA directed against a target gene. This technique has emerged as powerful tool in understanding the functions of a number of genes in recent years. For the improvement in the nutritional status of the plants and reduction in the level of antinutrients, the conventional breeding methods were not completely successful in achieving the tissue-specific regulation of some genes. RNAi has shown successful results in a number of plant species for nutritional improvement, change in morphology and alteration in metabolite synthesis. This technology has been applied mostly in genetic engineering of important crop plants, and till date there are no reports of its application for the improvement of traditional/underutilized crops. In this study, we discuss current knowledge of RNAi function and concept and strategies for the improvement of traditional crops. Practical application. Although RNAi has been extensively used for the improvement of popular crops, no attention has been given for the use of this technology for the improvement of underutilized crops. This study describes the importance of use of this technology for the improvement of underutilized crops.

  11. An Improved Ghost-cell Immersed Boundary Method for Compressible Inviscid Flow Simulations

    KAUST Repository

    Chi, Cheng

    2015-01-01

    This study presents an improved ghost-cell immersed boundary approach to represent a solid body in compressible flow simulations. In contrast to the commonly used approaches, in the present work ghost cells are mirrored through the boundary

  12. Evaluation of an improved method of simulating lung nodules in chest tomosynthesis

    International Nuclear Information System (INIS)

    Svalkvist, Angelica; Allansdotter Johnsson, Aase; Vikgren, Jenny

    2012-01-01

    Background Simulated pathology is a valuable complement to clinical images in studies aiming at evaluating an imaging technique. In order for a study using simulated pathology to be valid, it is important that the simulated pathology in a realistic way reflect the characteristics of real pathology. Purpose To perform a thorough evaluation of a nodule simulation method for chest tomosynthesis, comparing the detection rate and appearance of the artificial nodules with those of real nodules in an observer performance experiment. Material and Methods A cohort consisting of 64 patients, 38 patients with a total of 129 identified pulmonary nodules and 26 patients without identified pulmonary nodules, was used in the study. Simulated nodules, matching the real clinically found pulmonary nodules by size, attenuation, and location, were created and randomly inserted into the tomosynthesis section images of the patients. Three thoracic radiologists and one radiology resident reviewed the images in an observer performance study divided into two parts. The first part included nodule detection and the second part included rating of the visual appearance of the nodules. The results were evaluated using a modified receiver-operating characteristic (ROC) analysis. Results The sensitivities for real and simulated nodules were comparable, as the area under the modified ROC curve (AUC) was close to 0.5 for all observers (range, 0.43-0.55). Even though the ratings of visual appearance for real and simulated nodules overlapped considerably, the statistical analysis revealed that the observers to were able to separate simulated nodules from real nodules (AUC values range 0.70-0.74). Conclusion The simulation method can be used to create artificial lung nodules that have similar detectability as real nodules in chest tomosynthesis, although experienced thoracic radiologists may be able to distinguish them from real nodules

  13. Use of a colon simulation technique to assess the effect of live yeast on fermentation parameters and microbiota of the colon of pig.

    Science.gov (United States)

    Pinloche, E; Williams, M; D'Inca, R; Auclair, E; Newbold, C J

    2012-12-01

    The impact of 2 doses of a Saccharomyces cerevisiae were evaluated, 5 × 10(10) cfu/kg of feed (L1) and 5 × 10(11) cfu/kg of feed (L2) against a control (CON) with no added yeast, using an in vitro model [colon simulation technique (Cositec)] to mimic digestion in the pig colon. The L2 (but not L1) dose significantly improved DM digestibility compared to CON (61 v 58%) and increased NH(3) concentrations (+15%). Volatile fatty acid concentrations increased with L2 compared to CON--isobutyrate (+13.5%), propionate (+8.5%), isovalerate (+17.8%), and valerate (+25%)--but only valerate was increased with L1 (+14.2%). The analysis of microbiota from the liquid associated bacteria (LAB) and solid associated bacteria (SAB) revealed an interaction between the fraction and treatment (P simulation model but only at the higher dose used and this effect was associated with a shift in the bacterial population therein.

  14. Determination of true coincidence correction factors using Monte-Carlo simulation techniques

    Directory of Open Access Journals (Sweden)

    Chionis Dionysios A.

    2014-01-01

    Full Text Available Aim of this work is the numerical calculation of the true coincidence correction factors by means of Monte-Carlo simulation techniques. For this purpose, the Monte Carlo computer code PENELOPE was used and the main program PENMAIN was properly modified in order to include the effect of the true coincidence phenomenon. The modified main program that takes into consideration the true coincidence phenomenon was used for the full energy peak efficiency determination of an XtRa Ge detector with relative efficiency 104% and the results obtained for the 1173 keV and 1332 keV photons of 60Co were found consistent with respective experimental ones. The true coincidence correction factors were calculated as the ratio of the full energy peak efficiencies was determined from the original main program PENMAIN and the modified main program PENMAIN. The developed technique was applied for 57Co, 88Y, and 134Cs and for two source-to-detector geometries. The results obtained were compared with true coincidence correction factors calculated from the "TrueCoinc" program and the relative bias was found to be less than 2%, 4%, and 8% for 57Co, 88Y, and 134Cs, respectively.

  15. Improved thermal lattice Boltzmann model for simulation of liquid-vapor phase change

    Science.gov (United States)

    Li, Qing; Zhou, P.; Yan, H. J.

    2017-12-01

    In this paper, an improved thermal lattice Boltzmann (LB) model is proposed for simulating liquid-vapor phase change, which is aimed at improving an existing thermal LB model for liquid-vapor phase change [S. Gong and P. Cheng, Int. J. Heat Mass Transfer 55, 4923 (2012), 10.1016/j.ijheatmasstransfer.2012.04.037]. First, we emphasize that the replacement of ∇ .(λ ∇ T ) /∇.(λ ∇ T ) ρ cV ρ cV with ∇ .(χ ∇ T ) is an inappropriate treatment for diffuse interface modeling of liquid-vapor phase change. Furthermore, the error terms ∂t 0(T v ) +∇ .(T vv ) , which exist in the macroscopic temperature equation recovered from the previous model, are eliminated in the present model through a way that is consistent with the philosophy of the LB method. Moreover, the discrete effect of the source term is also eliminated in the present model. Numerical simulations are performed for droplet evaporation and bubble nucleation to validate the capability of the model for simulating liquid-vapor phase change. It is shown that the numerical results of the improved model agree well with those of a finite-difference scheme. Meanwhile, it is found that the replacement of ∇ .(λ ∇ T ) /∇ .(λ ∇ T ) ρ cV ρ cV with ∇ .(χ ∇ T ) leads to significant numerical errors and the error terms in the recovered macroscopic temperature equation also result in considerable errors.

  16. Effects of running with backpack loads during simulated gravitational transitions: Improvements in postural control

    Science.gov (United States)

    Brewer, Jeffrey David

    The National Aeronautics and Space Administration is planning for long-duration manned missions to the Moon and Mars. For feasible long-duration space travel, improvements in exercise countermeasures are necessary to maintain cardiovascular fitness, bone mass throughout the body and the ability to perform coordinated movements in a constant gravitational environment that is six orders of magnitude higher than the "near weightlessness" condition experienced during transit to and/or orbit of the Moon, Mars, and Earth. In such gravitational transitions feedback and feedforward postural control strategies must be recalibrated to ensure optimal locomotion performance. In order to investigate methods of improving postural control adaptation during these gravitational transitions, a treadmill based precision stepping task was developed to reveal changes in neuromuscular control of locomotion following both simulated partial gravity exposure and post-simulation exercise countermeasures designed to speed lower extremity impedance adjustment mechanisms. The exercise countermeasures included a short period of running with or without backpack loads immediately after partial gravity running. A novel suspension type partial gravity simulator incorporating spring balancers and a motor-driven treadmill was developed to facilitate body weight off loading and various gait patterns in both simulated partial and full gravitational environments. Studies have provided evidence that suggests: the environmental simulator constructed for this thesis effort does induce locomotor adaptations following partial gravity running; the precision stepping task may be a helpful test for illuminating these adaptations; and musculoskeletal loading in the form of running with or without backpack loads may improve the locomotor adaptation process.

  17. A High Performance Silicon-on-Insulator LDMOSTT Using Linearly Increasing Thickness Techniques

    International Nuclear Information System (INIS)

    Yu-Feng, Guo; Zhi-Gong, Wang; Gene, Sheu; Jian-Bing, Cheng

    2010-01-01

    We present a new technique to achieve uniform lateral electric field and maximum breakdown voltage in lateral double-diffused metal-oxide-semiconductor transistors fabricated on silicon-on-insulator substrates. A linearly increasing drift-region thickness from the source to the drain is employed to improve the electric field distribution in the devices. Compared to the lateral linear doping technique and the reduced surface field technique, two-dimensional numerical simulations show that the new device exhibits reduced specific on-resistance, maximum off- and on-state breakdown voltages, superior quasi-saturation characteristics and improved safe operating area. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  18. Improved parallel solution techniques for the integral transport matrix method

    Energy Technology Data Exchange (ETDEWEB)

    Zerr, R. Joseph, E-mail: rjz116@psu.edu [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA (United States); Azmy, Yousry Y., E-mail: yyazmy@ncsu.edu [Department of Nuclear Engineering, North Carolina State University, Burlington Engineering Laboratories, Raleigh, NC (United States)

    2011-07-01

    Alternative solution strategies to the parallel block Jacobi (PBJ) method for the solution of the global problem with the integral transport matrix method operators have been designed and tested. The most straightforward improvement to the Jacobi iterative method is the Gauss-Seidel alternative. The parallel red-black Gauss-Seidel (PGS) algorithm can improve on the number of iterations and reduce work per iteration by applying an alternating red-black color-set to the subdomains and assigning multiple sub-domains per processor. A parallel GMRES(m) method was implemented as an alternative to stationary iterations. Computational results show that the PGS method can improve on the PBJ method execution time by up to 10´ when eight sub-domains per processor are used. However, compared to traditional source iterations with diffusion synthetic acceleration, it is still approximately an order of magnitude slower. The best-performing cases are optically thick because sub-domains decouple, yielding faster convergence. Further tests revealed that 64 sub-domains per processor was the best performing level of sub-domain division. An acceleration technique that improves the convergence rate would greatly improve the ITMM. The GMRES(m) method with a diagonal block pre conditioner consumes approximately the same time as the PBJ solver but could be improved by an as yet undeveloped, more efficient pre conditioner. (author)

  19. Improved parallel solution techniques for the integral transport matrix method

    International Nuclear Information System (INIS)

    Zerr, R. Joseph; Azmy, Yousry Y.

    2011-01-01

    Alternative solution strategies to the parallel block Jacobi (PBJ) method for the solution of the global problem with the integral transport matrix method operators have been designed and tested. The most straightforward improvement to the Jacobi iterative method is the Gauss-Seidel alternative. The parallel red-black Gauss-Seidel (PGS) algorithm can improve on the number of iterations and reduce work per iteration by applying an alternating red-black color-set to the subdomains and assigning multiple sub-domains per processor. A parallel GMRES(m) method was implemented as an alternative to stationary iterations. Computational results show that the PGS method can improve on the PBJ method execution time by up to 10´ when eight sub-domains per processor are used. However, compared to traditional source iterations with diffusion synthetic acceleration, it is still approximately an order of magnitude slower. The best-performing cases are optically thick because sub-domains decouple, yielding faster convergence. Further tests revealed that 64 sub-domains per processor was the best performing level of sub-domain division. An acceleration technique that improves the convergence rate would greatly improve the ITMM. The GMRES(m) method with a diagonal block pre conditioner consumes approximately the same time as the PBJ solver but could be improved by an as yet undeveloped, more efficient pre conditioner. (author)

  20. Full scope simulator of a nuclear power plant control room using 3D stereo virtual reality techniques for operators training

    International Nuclear Information System (INIS)

    Aghina, Mauricio A.C.; Mol, Antonio Carlos A.; Almeida, Adino Americo A.; Pereira, Claudio M.N.A.; Varela, Thiago F.B.

    2007-01-01

    Practical training of nuclear power plants operators are partially performed by means of simulators. Usually these simulators are physical copies of the original control roam, needing a large space on a facility being also very expensive. In this way, the proposal of this paper is to implement the use of Virtual Reality techniques to design a full scope control room simulator, in a manner to reduce costs and physical space usage. (author)

  1. Utilization of induced mutation techniques in rice improvement in the Philippines

    International Nuclear Information System (INIS)

    Asencion, A.B.; Santos, I.S.; Barrida, A.C.; Medina, F.I.S. III

    2001-01-01

    Rice is one of the most important food crops in the Philippines, as such, efforts have been made consistently to improve the varieties released to the farmers for planting. Both conventional and induced mutation techniques were utilized to solve some of the problems. Varieties with improved qualities, resistance to pests and diseases, reduced height, early maturity and non-photoperiod sensitive were developed using either physical or chemical mutagen. Other methods were also tried to enhance variability like combination of gamma irradiation and biotechnology. Irradiation of F1 seeds was also initiated including the use of mutants in crosses to transfer their improved mutated characters. Promising selections were already tested and six lines from the F1 irradiation out-yielded both C4-63G and IR 1561-288-3, their parents. (author)

  2. Utilization of induced mutation techniques in rice improvement in the Philippines

    Energy Technology Data Exchange (ETDEWEB)

    Asencion, A.B.; Santos, I.S.; Barrida, A.C.; Medina, F.I.S. III [Philippine Nuclear Research Institute, Atomic Research Center (Philippines)

    2001-03-01

    Rice is one of the most important food crops in the Philippines, as such, efforts have been made consistently to improve the varieties released to the farmers for planting. Both conventional and induced mutation techniques were utilized to solve some of the problems. Varieties with improved qualities, resistance to pests and diseases, reduced height, early maturity and non-photoperiod sensitive were developed using either physical or chemical mutagen. Other methods were also tried to enhance variability like combination of gamma irradiation and biotechnology. Irradiation of F1 seeds was also initiated including the use of mutants in crosses to transfer their improved mutated characters. Promising selections were already tested and six lines from the F1 irradiation out-yielded both C4-63G and IR 1561-288-3, their parents. (author)

  3. Advanced Hydroinformatic Techniques for the Simulation and Analysis of Water Supply and Distribution Systems

    OpenAIRE

    Herrera, Manuel; Meniconi, Silvia; Alvisi, Stefano; Izquierdo, Joaquin

    2018-01-01

    This document is intended to be a presentation of the Special Issue “Advanced Hydroinformatic Techniques for the Simulation and Analysis of Water Supply and Distribution Systems”. The final aim of this Special Issue is to propose a suitable framework supporting insightful hydraulic mechanisms to aid the decision-making processes of water utility managers and practitioners. Its 18 peer-reviewed articles present as varied topics as: water distribution system design, optimization of network perf...

  4. An improved detector response simulation for the CBM silicon tracking system

    Energy Technology Data Exchange (ETDEWEB)

    Malygina, Hanna [Goethe University, Frankfurt (Germany); Friese, Volker [GSI, Darmstadt (Germany); Collaboration: CBM-Collaboration

    2015-07-01

    The Compressed Baryonic Matter experiment(CBM) at FAIR is designed to explore the QCD phase diagram in the region of high net-baryon densities. The central detector component the Silicon Tracking System (STS) is build from double-sided micro-strip sensors. To achieve realistic simulations the response of the silicon strip sensors should be precisely included in the digitizer which simulates a complete chain of physical processes caused by charged particles traversing the detector, from charge creation in silicon to a digital output signal. The new version of the STS digitizer comprises in addition non-uniform energy loss distributions (according to the Urban theory), thermal diffusion and charge redistribution over the read-out channels due to interstrip capacitances. The improved response simulation was tested with parameters reproducing the anticipated running conditions of the CBM experiment. Two different method for cluster finding were used. The results for hit position residuals, cluster size distribution, as well as for some other parameters of reconstruction quality are presented. The achieved advance is assessed by a comparison with the previous, simpler version of the STS detector response simulation.

  5. European-wide simulations of croplands using an improved terrestrial biosphere model: Phenology and productivity

    Science.gov (United States)

    Smith, P. C.; de Noblet-Ducoudré, N.; Ciais, P.; Peylin, P.; Viovy, N.; Meurdesoif, Y.; Bondeau, A.

    2010-03-01

    Aiming at producing improved estimates of carbon source/sink spatial and interannual patterns across Europe (35% croplands), this work combines the terrestrial biosphere model Organizing Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE), for vegetation productivity, water balance, and soil carbon dynamics, and the generic crop model Simulateur Multidisciplinaire pour les Cultures Standard (STICS), for phenology, irrigation, nitrogen balance, and harvest. The ORCHIDEE-STICS model, relying on three plant functional types for the representation of temperate agriculture, is evaluated over the last few decades at various spatial and temporal resolutions. The simulated leaf area index seasonal cycle is largely improved relative to the original ORCHIDEE simulating grasslands, and compares favorably with remote-sensing observations (correlation doubles over Europe). Crop yield is derived from annual net primary productivity and compared with wheat and grain maize harvest data for five European countries. Discrepancies between 30 year mean simulated and reported yields are large in Mediterranean countries. Interannual variability amplitude expressed relative to the mean is reduced toward the observed variability (≈10%) when using ORCHIDEE-STICS. Overall, this study highlights the importance of accounting for the specific phenologies of crops sown both in winter and in spring and for irrigation applied to spring crops in regional/global models of the terrestrial carbon cycle. Limitations suggest to account for temporal and spatial variability in agricultural practices for further simulation improvement.

  6. Improvement and Simulation of THOR Formula with Yaw Angle

    Directory of Open Access Journals (Sweden)

    Jie Wang

    2014-04-01

    Full Text Available The THOR formula is widely used in the investigation of vulnerability and effectiveness of weapon system, however, its application was limited by the small slenderness ratio and limited materials of target. In order to investigate the damage effect of KE-rod warhead, this paper, basing on the classic THOR formula, focused on improving the formula of residual velocity and residual mass. The improved THOR model could predict the residual velocity and residual mass of KE-rod penetration in the complex conditions, and the predictions were found to be consistent with the experimental numerical results in the literatures. As the experimental data is limited, for the better validation of the improved formula, the paper investigated further research and verification of the improvement THOR formula with numerical simulation. Since the experimental data are limited for hypervelocity impact, comparisons of results between M-THOR with experimental and numerical data were widely preceded. The error is less than 4.8% for the predicted residual velocity while 5.4% for predicted residual velocity. The effect of yaw angle in the modified THOR formula was also found to agree quite well with the reference.

  7. Improved techniques for appendage attachment to PHWR fuel elements

    International Nuclear Information System (INIS)

    Raj, R.N.J.; Laxminarayana, B.; Narayanan, P.S.A.; Gupta, U.C.; Varma, B.P.; Sinha, K.K.

    1995-01-01

    Nuclear Fuel Complex, India switched-over to split-wart type PHWR fuel bundles in mid-80s. Since then over 60,000 bundles of this type have been fabricated for Indian PHWRs. After considering various technical aspects, resistance welding was chosen for appendage attachment to the fuel elements. The paper describes experiences in scaling up of the technique to industrial production of PHWR fuel bundles, design and development of special-purpose equipment for this purpose, and the QA procedures employed for regular production. It also deals with appendage welding of 37 Element fuel bundles and improvements planned in the appendage welding process. (author)

  8. The Parameters Optimization of MCR-WPT System Based on the Improved Genetic Simulated Annealing Algorithm

    Directory of Open Access Journals (Sweden)

    Sheng Lu

    2015-01-01

    Full Text Available To solve the problem of parameter selection during the design of magnetically coupled resonant wireless power transmission system (MCR-WPT, this paper proposed an improved genetic simulated annealing algorithm. Firstly, the equivalent circuit of the system is analysis in this study and a nonlinear programming mathematical model is built. Secondly, in place of the penalty function method in the genetic algorithm, the selection strategy based on the distance between individuals is adopted to select individual. In this way, it reduces the excess empirical parameters. Meanwhile, it can improve the convergence rate and the searching ability by calculating crossover probability and mutation probability according to the variance of population’s fitness. At last, the simulated annealing operator is added to increase local search ability of the method. The simulation shows that the improved method can break the limit of the local optimum solution and get the global optimum solution faster. The optimized system can achieve the practical requirements.

  9. Reduction technique of drop voltage and power losses to improve power quality using ETAP Power Station simulation model

    Science.gov (United States)

    Satrio, Reza Indra; Subiyanto

    2018-03-01

    The effect of electric loads growth emerged direct impact in power systems distribution. Drop voltage and power losses one of the important things in power systems distribution. This paper presents modelling approach used to restructrure electrical network configuration, reduce drop voltage, reduce power losses and add new distribution transformer to enhance reliability of power systems distribution. Restructrure electrical network was aimed to analyse and investigate electric loads of a distribution transformer. Measurement of real voltage and real current were finished two times for each consumer, that were morning period and night period or when peak load. Design and simulation were conduct by using ETAP Power Station Software. Based on result of simulation and real measurement precentage of drop voltage and total power losses were mismatch with SPLN (Standard PLN) 72:1987. After added a new distribution transformer and restructrured electricity network configuration, the result of simulation could reduce drop voltage from 1.3 % - 31.3 % to 8.1 % - 9.6 % and power losses from 646.7 watt to 233.29 watt. Result showed, restructrure electricity network configuration and added new distribution transformer can be applied as an effective method to reduce drop voltage and reduce power losses.

  10. Improving the trust in results of numerical simulations and scientific data analytics

    Energy Technology Data Exchange (ETDEWEB)

    Cappello, Franck [Argonne National Lab. (ANL), Argonne, IL (United States); Constantinescu, Emil [Argonne National Lab. (ANL), Argonne, IL (United States); Hovland, Paul [Argonne National Lab. (ANL), Argonne, IL (United States); Peterka, Tom [Argonne National Lab. (ANL), Argonne, IL (United States); Phillips, Carolyn [Argonne National Lab. (ANL), Argonne, IL (United States); Snir, Marc [Argonne National Lab. (ANL), Argonne, IL (United States); Wild, Stefan [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-04-30

    This white paper investigates several key aspects of the trust that a user can give to the results of numerical simulations and scientific data analytics. In this document, the notion of trust is related to the integrity of numerical simulations and data analytics applications. This white paper complements the DOE ASCR report on Cybersecurity for Scientific Computing Integrity by (1) exploring the sources of trust loss; (2) reviewing the definitions of trust in several areas; (3) providing numerous cases of result alteration, some of them leading to catastrophic failures; (4) examining the current notion of trust in numerical simulation and scientific data analytics; (5) providing a gap analysis; and (6) suggesting two important research directions and their respective research topics. To simplify the presentation without loss of generality, we consider that trust in results can be lost (or the results’ integrity impaired) because of any form of corruption happening during the execution of the numerical simulation or the data analytics application. In general, the sources of such corruption are threefold: errors, bugs, and attacks. Current applications are already using techniques to deal with different types of corruption. However, not all potential corruptions are covered by these techniques. We firmly believe that the current level of trust that a user has in the results is at least partially founded on ignorance of this issue or the hope that no undetected corruptions will occur during the execution. This white paper explores the notion of trust and suggests recommendations for developing a more scientifically grounded notion of trust in numerical simulation and scientific data analytics. We first formulate the problem and show that it goes beyond previous questions regarding the quality of results such as V&V, uncertainly quantification, and data assimilation. We then explore the complexity of this difficult problem, and we sketch complementary general

  11. Does teaching non-technical skills to medical students improve those skills and simulated patient outcome?

    Science.gov (United States)

    Hagemann, Vera; Herbstreit, Frank; Kehren, Clemens; Chittamadathil, Jilson; Wolfertz, Sandra; Dirkmann, Daniel; Kluge, Annette; Peters, Jürgen

    2017-03-29

    The purpose of this study is to evaluate the effects of a tailor-made, non-technical skills seminar on medical student's behaviour, attitudes, and performance during simulated patient treatment. Seventy-seven students were randomized to either a non-technical skills seminar (NTS group, n=43) or a medical seminar (control group, n=34). The human patient simulation was used as an evaluation tool. Before the seminars, all students performed the same simulated emergency scenario to provide baseline measurements. After the seminars, all students were exposed to a second scenario, and behavioural markers for evaluating their non-technical skills were rated. Furthermore, teamwork-relevant attitudes were measured before and after the scenarios, and perceived stress was measured following each simulation. All simulations were also evaluated for various medical endpoints. Non-technical skills concerning situation awareness (ptechnical skills to improve student's non-technical skills. In a next step, to improve student's handling of emergencies and patient outcomes, non-technical skills seminars should be accompanied by exercises and more broadly embedded in the medical school curriculum.

  12. New Technique for Improving Performance of LDPC Codes in the Presence of Trapping Sets

    Directory of Open Access Journals (Sweden)

    Mohamed Adnan Landolsi

    2008-06-01

    Full Text Available Trapping sets are considered the primary factor for degrading the performance of low-density parity-check (LDPC codes in the error-floor region. The effect of trapping sets on the performance of an LDPC code becomes worse as the code size decreases. One approach to tackle this problem is to minimize trapping sets during LDPC code design. However, while trapping sets can be reduced, their complete elimination is infeasible due to the presence of cycles in the underlying LDPC code bipartite graph. In this work, we introduce a new technique based on trapping sets neutralization to minimize the negative effect of trapping sets under belief propagation (BP decoding. Simulation results for random, progressive edge growth (PEG and MacKay LDPC codes demonstrate the effectiveness of the proposed technique. The hardware cost of the proposed technique is also shown to be minimal.

  13. Linking Six Sigma to simulation: a new roadmap to improve the quality of patient care.

    Science.gov (United States)

    Celano, Giovanni; Costa, Antonio; Fichera, Sergio; Tringali, Giuseppe

    2012-01-01

    Improving the quality of patient care is a challenge that calls for a multidisciplinary approach, embedding a broad spectrum of knowledge and involving healthcare professionals from diverse backgrounds. The purpose of this paper is to present an innovative approach that implements discrete-event simulation (DES) as a decision-supporting tool in the management of Six Sigma quality improvement projects. A roadmap is designed to assist quality practitioners and health care professionals in the design and successful implementation of simulation models within the define-measure-analyse-design-verify (DMADV) or define-measure-analyse-improve-control (DMAIC) Six Sigma procedures. A case regarding the reorganisation of the flow of emergency patients affected by vertigo symptoms was developed in a large town hospital as a preliminary test of the roadmap. The positive feedback from professionals carrying out the project looks promising and encourages further roadmap testing in other clinical settings. The roadmap is a structured procedure that people involved in quality improvement can implement to manage projects based on the analysis and comparison of alternative scenarios. The role of Six Sigma philosophy in improvement of the quality of healthcare services is recognised both by researchers and by quality practitioners; discrete-event simulation models are commonly used to improve the key performance measures of patient care delivery. The two approaches are seldom referenced and implemented together; however, they could be successfully integrated to carry out quality improvement programs. This paper proposes an innovative approach to bridge the gap and enrich the Six Sigma toolbox of quality improvement procedures with DES.

  14. Peptide dynamics by molecular dynamics simulation and diffusion theory method with improved basis sets

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Po Jen; Lai, S. K., E-mail: sklai@coll.phy.ncu.edu.tw [Complex Liquids Laboratory, Department of Physics, National Central University, Chungli 320, Taiwan and Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan (China); Rapallo, Arnaldo [Istituto per lo Studio delle Macromolecole (ISMAC) Consiglio Nazionale delle Ricerche (CNR), via E. Bassini 15, C.A.P 20133 Milano (Italy)

    2014-03-14

    Improved basis sets for the study of polymer dynamics by means of the diffusion theory, and tests on a melt of cis-1,4-polyisoprene decamers, and a toluene solution of a 71-mer syndiotactic trans-1,2-polypentadiene were presented recently [R. Gaspari and A. Rapallo, J. Chem. Phys. 128, 244109 (2008)]. The proposed hybrid basis approach (HBA) combined two techniques, the long time sorting procedure and the maximum correlation approximation. The HBA takes advantage of the strength of these two techniques, and its basis sets proved to be very effective and computationally convenient in describing both local and global dynamics in cases of flexible synthetic polymers where the repeating unit is a unique type of monomer. The question then arises if the same efficacy continues when the HBA is applied to polymers of different monomers, variable local stiffness along the chain and with longer persistence length, which have different local and global dynamical properties against the above-mentioned systems. Important examples of this kind of molecular chains are the proteins, so that a fragment of the protein transthyretin is chosen as the system of the present study. This peptide corresponds to a sequence that is structured in β-sheets of the protein and is located on the surface of the channel with thyroxin. The protein transthyretin forms amyloid fibrils in vivo, whereas the peptide fragment has been shown [C. P. Jaroniec, C. E. MacPhee, N. S. Astrof, C. M. Dobson, and R. G. Griffin, Proc. Natl. Acad. Sci. U.S.A. 99, 16748 (2002)] to form amyloid fibrils in vitro in extended β-sheet conformations. For these reasons the latter is given considerable attention in the literature and studied also as an isolated fragment in water solution where both experimental and theoretical efforts have indicated the propensity of the system to form β turns or α helices, but is otherwise predominantly unstructured. Differing from previous computational studies that employed implicit

  15. Peptide dynamics by molecular dynamics simulation and diffusion theory method with improved basis sets

    International Nuclear Information System (INIS)

    Hsu, Po Jen; Lai, S. K.; Rapallo, Arnaldo

    2014-01-01

    Improved basis sets for the study of polymer dynamics by means of the diffusion theory, and tests on a melt of cis-1,4-polyisoprene decamers, and a toluene solution of a 71-mer syndiotactic trans-1,2-polypentadiene were presented recently [R. Gaspari and A. Rapallo, J. Chem. Phys. 128, 244109 (2008)]. The proposed hybrid basis approach (HBA) combined two techniques, the long time sorting procedure and the maximum correlation approximation. The HBA takes advantage of the strength of these two techniques, and its basis sets proved to be very effective and computationally convenient in describing both local and global dynamics in cases of flexible synthetic polymers where the repeating unit is a unique type of monomer. The question then arises if the same efficacy continues when the HBA is applied to polymers of different monomers, variable local stiffness along the chain and with longer persistence length, which have different local and global dynamical properties against the above-mentioned systems. Important examples of this kind of molecular chains are the proteins, so that a fragment of the protein transthyretin is chosen as the system of the present study. This peptide corresponds to a sequence that is structured in β-sheets of the protein and is located on the surface of the channel with thyroxin. The protein transthyretin forms amyloid fibrils in vivo, whereas the peptide fragment has been shown [C. P. Jaroniec, C. E. MacPhee, N. S. Astrof, C. M. Dobson, and R. G. Griffin, Proc. Natl. Acad. Sci. U.S.A. 99, 16748 (2002)] to form amyloid fibrils in vitro in extended β-sheet conformations. For these reasons the latter is given considerable attention in the literature and studied also as an isolated fragment in water solution where both experimental and theoretical efforts have indicated the propensity of the system to form β turns or α helices, but is otherwise predominantly unstructured. Differing from previous computational studies that employed implicit

  16. An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ying, C. K. [Advanced Medical and Dental Institute, AMDI, Universiti Sains Malaysia, Penang, Malaysia and School of Medical Sciences, Universiti Sains Malaysia, Kota Bharu (Malaysia); Kamil, W. A. [Advanced Medical and Dental Institute, AMDI, Universiti Sains Malaysia, Penang, Malaysia and Radiology Department, Hospital USM, Kota Bharu (Malaysia); Shuaib, I. L. [Advanced Medical and Dental Institute, AMDI, Universiti Sains Malaysia, Penang (Malaysia); Matsufuji, Naruhiro [Research Centre of Charged Particle Therapy, National Institute of Radiological Sciences, NIRS, Chiba (Japan)

    2014-02-12

    Heavy-particle therapy such as carbon ion therapy are more popular nowadays because of the nature characteristics of charged particle and almost no side effect to patients. An effective treatment is achieved with high precision of dose calculation, in this research work, Geant4 based Monte Carlo simulation method has been used to calculate the radiation transport and dose distribution. The simulation have the same setting with the treatment room in Heavy Ion Medical Accelerator, HIMAC. The carbon ion beam at the isocentric gantry nozzle for the therapeutic energy of 290 MeV/u was simulated, experimental work was carried out in National Institute of Radiological Sciences, NIRS, Chiba, Japan by using the HIMAC to confirm the accuracy and qualities dose distribution by MC methods. The Geant4 based simulated dose distribution were verified with measurements for Bragg peak and spread out Bragg peak (SOBP) respectively. The verification of results shows that the Bragg peak depth-dose and SOBP distributions in simulation has good agreement with measurements. In overall, the study showed that Geant4 based can be fully applied in the heavy-ion therapy field for simulation, further works need to be carry on to refine and improve the Geant4 MC simulations.

  17. An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy

    International Nuclear Information System (INIS)

    Ying, C. K.; Kamil, W. A.; Shuaib, I. L.; Matsufuji, Naruhiro

    2014-01-01

    Heavy-particle therapy such as carbon ion therapy are more popular nowadays because of the nature characteristics of charged particle and almost no side effect to patients. An effective treatment is achieved with high precision of dose calculation, in this research work, Geant4 based Monte Carlo simulation method has been used to calculate the radiation transport and dose distribution. The simulation have the same setting with the treatment room in Heavy Ion Medical Accelerator, HIMAC. The carbon ion beam at the isocentric gantry nozzle for the therapeutic energy of 290 MeV/u was simulated, experimental work was carried out in National Institute of Radiological Sciences, NIRS, Chiba, Japan by using the HIMAC to confirm the accuracy and qualities dose distribution by MC methods. The Geant4 based simulated dose distribution were verified with measurements for Bragg peak and spread out Bragg peak (SOBP) respectively. The verification of results shows that the Bragg peak depth-dose and SOBP distributions in simulation has good agreement with measurements. In overall, the study showed that Geant4 based can be fully applied in the heavy-ion therapy field for simulation, further works need to be carry on to refine and improve the Geant4 MC simulations

  18. An improved Monte Carlo (MC) dose simulation for charged particle cancer therapy

    International Nuclear Information System (INIS)

    Ying, C.K.; Kamil, W.A.; Shuaib, I.L.; Ying, C.K.; Kamil, W.A.

    2013-01-01

    Full-text: Heavy-particle therapy such as carbon ion therapy are more popular nowadays because of the nature characteristics of charged particle and almost no side effect to patients. An effective treatment is achieved with high precision of dose calculation, in this research work, Geant4 based Monte Carlo simulation method has been used to calculate the radiation transport and dose distribution. The simulation have the same setting with the treatment room in Heavy Ion Medical Accelerator, HIMAC. The carbon ion beam at the isocentric gantry nozzle for the therapeutic energy of 290 MeV/u was simulated, experimental work was carried out in National Institute of Radiological Sciences, NIRS, Chiba, Japan by using the HIMAC to confirm the accuracy and qualities dose distribution by MC methods. The Geant4 based simulated dose distribution were verified with measurements for Bragg peak and spread out Bragg peak (SOBP) respectively. The verification of results shows that the Bragg peak depth-dose and SOBP distributions in simulation has good agreement with measurements. In overall, the study showed that Geant4 based can be fully applied in the heavy ion therapy field for simulation, further works need to be carry on to refine and improve the Geant4 MC simulations. (author)