Science.gov

Sample records for dynamic performance analysis

  1. Managing Performance Analysis with Dynamic Statistical Projection Pursuit

    SciTech Connect

    Vetter, J.S.; Reed, D.A.

    2000-05-22

    Computer systems and applications are growing more complex. Consequently, performance analysis has become more difficult due to the complex, transient interrelationships among runtime components. To diagnose these types of performance issues, developers must use detailed instrumentation to capture a large number of performance metrics. Unfortunately, this instrumentation may actually influence the performance analysis, leading the developer to an ambiguous conclusion. In this paper, we introduce a technique for focusing a performance analysis on interesting performance metrics. This technique, called dynamic statistical projection pursuit, identifies interesting performance metrics that the monitoring system should capture across some number of processors. By reducing the number of performance metrics, projection pursuit can limit the impact of instrumentation on the performance of the target system and can reduce the volume of performance data.

  2. Dynamic performances analysis of a real vehicle driving

    NASA Astrophysics Data System (ADS)

    Abdullah, M. A.; Jamil, J. F.; Salim, M. A.

    2015-12-01

    Vehicle dynamic is the effects of movement of a vehicle generated from the acceleration, braking, ride and handling activities. The dynamic behaviours are determined by the forces from tire, gravity and aerodynamic which acting on the vehicle. This paper emphasizes the analysis of vehicle dynamic performance of a real vehicle. Real driving experiment on the vehicle is conducted to determine the effect of vehicle based on roll, pitch, and yaw, longitudinal, lateral and vertical acceleration. The experiment is done using the accelerometer to record the reading of the vehicle dynamic performance when the vehicle is driven on the road. The experiment starts with weighing a car model to get the center of gravity (COG) to place the accelerometer sensor for data acquisition (DAQ). The COG of the vehicle is determined by using the weight of the vehicle. A rural route is set to launch the experiment and the road conditions are determined for the test. The dynamic performance of the vehicle are depends on the road conditions and driving maneuver. The stability of a vehicle can be controlled by the dynamic performance analysis.

  3. Transient analysis techniques in performing impact and crash dynamic studies

    NASA Technical Reports Server (NTRS)

    Pifko, A. B.; Winter, R.

    1989-01-01

    Because of the emphasis being placed on crashworthiness as a design requirement, increasing demands are being made by various organizations to analyze a wide range of complex structures that must perform safely when subjected to severe impact loads, such as those generated in a crash event. The ultimate goal of crashworthiness design and analysis is to produce vehicles with the ability to reduce the dynamic forces experienced by the occupants to specified levels, while maintaining a survivable envelope around them during a specified crash event. DYCAST is a nonlinear structural dynamic finite element computer code that started from the plans systems of a finite element program for static nonlinear structural analysis. The essential features of DYCAST are outlined.

  4. Analysis of Dynamic Performances for Servo Drive Hydraulic System

    NASA Astrophysics Data System (ADS)

    Yang, Jianxi; Wang, Liying; Huang, Jian

    Based on the servo drive hydraulic of system, using MATLAB/Simulink software in this paper, the impacts on system dynamic performances are analyzed and simulated of all the parameters (structure parameters J, Dp, and mechanism parameters A1, α, k, V1 CP). According to the relation curve of the main systematic characteristics and dynamic performances obtained from the simulations, it provides advantages for system dynamic performance improvements. The simulation results indicate that dynamic performances can be improved through the reasonable selection of the system structural parameters. Also it laid the theoretical foundation for further study on energy saving of hydraulic injection machine.

  5. Dynamic Curvature Steering Control for Autonomous Vehicle: Performance Analysis

    NASA Astrophysics Data System (ADS)

    Aizzat Zakaria, Muhammad; Zamzuri, Hairi; Amri Mazlan, Saiful

    2016-02-01

    This paper discusses the design of dynamic curvature steering control for autonomous vehicle. The lateral control and longitudinal control are discussed in this paper. The controller is designed based on the dynamic curvature calculation to estimate the path condition and modify the vehicle speed and steering wheel angle accordingly. In this paper, the simulation results are presented to show the capability of the controller to track the reference path. The controller is able to predict the path and modify the vehicle speed to suit the path condition. The effectiveness of the controller is shown in this paper whereby identical performance is achieved with the benchmark but with extra curvature adaptation capabilites.

  6. Simulation analysis of dynamic working performance for star trackers.

    PubMed

    Shen, Juan; Zhang, Guangjun; Wei, Xinguo

    2010-12-01

    The elongated imaging track pertaining to a star spot recorded in the image sensor of a star tracker will diffuse over several pixels at a high angular velocity, leading to an inaccurate, even false, attitude value. A computer simulation of the attitude determination from a dynamic star tracker is developed first, based on a dynamic mathematical model of the star-spot imaging and an efficiency validation of the star centroiding algorithm in the dynamic condition. Then major error sources affecting the attitude accuracy in the dynamic condition are analyzed and discussed systematically based on the simulation results. A mathematical model calculating the average star number detected in the field of view is also deduced, using simulation results and signal processing theory, with image trailing ranging from 0 to 20 pixels during exposure. The summarized regularity is helpful in the system design and accuracy evaluation of a star tracker. PMID:21119749

  7. Human Performance Modeling for Dynamic Human Reliability Analysis

    SciTech Connect

    Boring, Ronald Laurids; Joe, Jeffrey Clark; Mandelli, Diego

    2015-08-01

    Part of the U.S. Department of Energy’s (DOE’s) Light Water Reac- tor Sustainability (LWRS) Program, the Risk-Informed Safety Margin Charac- terization (RISMC) Pathway develops approaches to estimating and managing safety margins. RISMC simulations pair deterministic plant physics models with probabilistic risk models. As human interactions are an essential element of plant risk, it is necessary to integrate human actions into the RISMC risk framework. In this paper, we review simulation based and non simulation based human reliability analysis (HRA) methods. This paper summarizes the founda- tional information needed to develop a feasible approach to modeling human in- teractions in RISMC simulations.

  8. School Expenditure and School Performance: Evidence from New South Wales Schools Using a Dynamic Panel Analysis

    ERIC Educational Resources Information Center

    Pugh, G.; Mangan, J.; Blackburn, V.; Radicic, D.

    2015-01-01

    This article estimates the effects of school expenditure on school performance in government secondary schools in New South Wales, Australia over the period 2006-2010. It uses dynamic panel analysis to exploit time series data on individual schools that only recently has become available. We find a significant but small effect of expenditure on…

  9. Dynamic Human Reliability Analysis: Benefits and Challenges of Simulating Human Performance

    SciTech Connect

    R. L. Boring

    2007-06-01

    To date, there has been considerable work on dynamic event trees and other areas related to dynamic probabilistic safety assessment (PSA). The counterpart to these efforts in human reliability analysis (HRA) has centered on the development of specific methods to account for the dynamic nature of human performance. In this paper, the author posits that the key to dynamic HRA is not in the development of specific methods but in the utilization of cognitive modeling and simulation to produce a framework of data that may be used in quantifying the likelihood of human error. This paper provides an overview of simulation approaches to HRA; reviews differences between first, second, and dynamic generation HRA; and outlines potential benefits and challenges of this approach.

  10. Performance evaluation of principal component analysis in dynamic FDG-PET studies of recurrent colorectal cancer.

    PubMed

    Thireou, Trias; Strauss, Ludwig G; Dimitrakopoulou-Strauss, Antonia; Kontaxakis, George; Pavlopoulos, Sotiris; Santos, Andres

    2003-01-01

    Performance evaluation of principal component analysis (PCA) of dynamic F-18-FDG-PET studies of patients with recurrent colorectal cancer. Principal component images (PCI) of 17 iteratively reconstructed data sets were visually and quantitatively evaluated. The F-18-FDG compartment model parameters were estimated using polynomial regression. All structures were present in PCI1. PCI2 was correlated with the vascular component and PCI3 with the tumor. The vessel density in the tumor was estimated with a correlation coefficient equal to 0.834. PCA supports the visual interpretation of dynamic F-18-FDG-PET studies, facilitates the application of compartment modeling and is a promising quantification technique. PMID:12573889

  11. Dynamic Analysis of Hybrid Energy Systems under Flexible Operation and Variable Renewable Generation -- Part I: Dynamic Performance Analysis and Part II: Dynamic Cost

    SciTech Connect

    Humberto E. Garcia; Amit Mohanty; Wen-Chiao Lin; Robert S. Cherry

    2013-04-01

    Dynamic analysis of hybrid energy systems (HES) under flexible operation and variable renewable generation is considered in order to better understand various challenges and opportunities associated with the high system variability arising from the integration of renewable energy into the power grid. Unique consequences are addressed by devising advanced HES solutions in which multiple forms of energy commodities, such as electricity and chemical products, may be exchanged. Dynamic models of various unit operations are developed and integrated within two different HES options. One HES option, termed traditional, produces electricity only and consists of a primary heat generator (PHG) (e.g., a small modular reactor), a steam turbine generator, a wind farm, and a battery storage. The other HES option, termed advanced, includes not only the components present in the traditional option but also a chemical plant complex to repurpose excess energy for non-electricity services, such as for the production of chemical goods (e.g., transportation fuel). In either case, a given HES is connected to the power grid at a point of common coupling and requested to deliver a certain electricity generation profile as dictated by a regional power grid operator based on a predicted demand curve. Dynamic analysis of these highly-coupled HES are performed to identify their key dynamical properties and limitations and to prescribe solutions for best managing and mitigating the high variability introduced from incorporating renewable energy into the energy mix. A comparative dynamic cost analysis is also conducted to determine best HES options. The cost function includes a set of metrics for computing fixed costs, such as fixed operations and maintenance (O&M) and overnight capital costs, and also variable operational costs, such as cost of variability, variable O&M cost, and cost of environmental impact, together with revenues. Assuming different options for implementing PHG (e

  12. Wind Evaluation Breadboard: mechanical design and analysis, control architecture, dynamic model, and performance simulation

    NASA Astrophysics Data System (ADS)

    Reyes García-Talavera, Marcos; Viera, Teodora; Núñez, Miguel; Zuluaga, Pablo; Ronquillo, Bernardo; Ronquillo, Mariano; Brunetto, Enzo; Quattri, Marco; Castro, Javier; Hernández, Elvio

    2008-07-01

    The Wind Evaluation Breadboard (WEB) for the European Extremely Large Telescope (ELT) is a primary mirror and telescope simulator formed by seven segments simulators, including position sensors, electromechanical support systems and support structures. The purpose of the WEB is to evaluate the performance of the control of wind buffeting disturbance on ELT segmented mirrors using an electro-mechanical set-up which simulates the real operational constrains applied to large segmented mirrors. The instrument has been designed and developed by IAC, ALTRAN, JUPASA and ESO, with FOGALE responsible of the Edge Sensors, and TNO of the Position Actuators. This paper describes the mechanical design and analysis, the control architecture, the dynamic model generated based on the Finite Element Model and the close loop performance achieved in simulations. A comparison in control performance between segments modal control and actuators local control is also presented.

  13. Causality analysis in business performance measurement system using system dynamics methodology

    NASA Astrophysics Data System (ADS)

    Yusof, Zainuridah; Yusoff, Wan Fadzilah Wan; Maarof, Faridah

    2014-07-01

    One of the main components of the Balanced Scorecard (BSC) that differentiates it from any other performance measurement system (PMS) is the Strategy Map with its unidirectional causality feature. Despite its apparent popularity, criticisms on the causality have been rigorously discussed by earlier researchers. In seeking empirical evidence of causality, propositions based on the service profit chain theory were developed and tested using the econometrics analysis, Granger causality test on the 45 data points. However, the insufficiency of well-established causality models was found as only 40% of the causal linkages were supported by the data. Expert knowledge was suggested to be used in the situations of insufficiency of historical data. The Delphi method was selected and conducted in obtaining the consensus of the causality existence among the 15 selected expert persons by utilizing 3 rounds of questionnaires. Study revealed that only 20% of the propositions were not supported. The existences of bidirectional causality which demonstrate significant dynamic environmental complexity through interaction among measures were obtained from both methods. With that, a computer modeling and simulation using System Dynamics (SD) methodology was develop as an experimental platform to identify how policies impacting the business performance in such environments. The reproduction, sensitivity and extreme condition tests were conducted onto developed SD model to ensure their capability in mimic the reality, robustness and validity for causality analysis platform. This study applied a theoretical service management model within the BSC domain to a practical situation using SD methodology where very limited work has been done.

  14. Performance evaluation of principal component analysis for dynamic fluorescence tomographic imaging in measurement space

    NASA Astrophysics Data System (ADS)

    Liu, Xin; He, Xiaowei; Yan, Zhuangzhi

    2015-05-01

    Challenges remain in resolving drug (fluorescent biomarkers) distributions within small animals by fluorescence diffuse optical tomography (FDOT). Principal component analysis (PCA) provides the capability of detecting organs (functional structures) from dynamic FDOT images. However, the resolving performance of PCA may be affected by various experimental factors, e.g., the noise levels in measurement data, the variance in optical properties, the number of acquired frames, and so on. To address the problem, based on a simulation model, we analyze and compare the performance of PCA when applied to three typical sets of experimental conditions (frames number, noise level, and optical properties). The results show that the noise is a critical factor affecting the performance of PCA. When input data containing a low noise (<5%), by a short (e.g., 6 frame) projection sequence, we can resolve the poly(DL-lactic-coglycolic acid)/indocynaine green (PLGA/ICG) distributions in heart and lungs, even though there are great variances in optical properties. In contrast, when 20% Gaussian noise is added to the input data, it hardly resolves the distributions of PLGA/ICG in heart and lungs even though accurate optical properties are used. However, with an increased number of frames, the resolving performance of PCA may gradually recover.

  15. Dynamic model and performance analysis of landing buffer for bionic locust mechanism

    NASA Astrophysics Data System (ADS)

    Chen, Dian-Sheng; Zhang, Zi-Qiang; Chen, Ke-Wei

    2016-06-01

    The landing buffer is an important problem in the research on bionic locust jumping robots, and the different modes of landing and buffering can affect the dynamic performance of the buffering process significantly. Based on an experimental observation, the different modes of landing and buffering are determined, which include the different numbers of landing legs and different motion modes of legs in the buffering process. Then a bionic locust mechanism is established, and the springs are used to replace the leg muscles to achieve a buffering effect. To reveal the dynamic performance in the buffering process of the bionic locust mechanism, a dynamic model is established with different modes of landing and buffering. In particular, to analyze the buffering process conveniently, an equivalent vibration dynamic model of the bionic locust mechanism is proposed. Given the support forces of the ground to the leg links, which can be obtained from the dynamic model, the spring forces of the legs and the impact resistance of each leg are the important parameters affecting buffering performance, and evaluation principles for buffering performance are proposed according to the aforementioned parameters. Based on the dynamic model and these evaluation principles, the buffering performances are analyzed and compared in different modes of landing and buffering on a horizontal plane and an inclined plane. The results show that the mechanism with the ends of the legs sliding can obtain a better dynamic performance. This study offers primary theories for buffering dynamics and an evaluation of landing buffer performance, and it establishes a theoretical basis for studies and engineering applications.

  16. Dynamic model and performance analysis of landing buffer for bionic locust mechanism

    NASA Astrophysics Data System (ADS)

    Chen, Dian-Sheng; Zhang, Zi-Qiang; Chen, Ke-Wei

    2015-10-01

    The landing buffer is an important problem in the research on bionic locust jumping robots, and the different modes of landing and buffering can affect the dynamic performance of the buffering process significantly. Based on an experimental observation, the different modes of landing and buffering are determined, which include the different numbers of landing legs and different motion modes of legs in the buffering process. Then a bionic locust mechanism is established, and the springs are used to replace the leg muscles to achieve a buffering effect. To reveal the dynamic performance in the buffering process of the bionic locust mechanism, a dynamic model is established with different modes of landing and buffering. In particular, to analyze the buffering process conveniently, an equivalent vibration dynamic model of the bionic locust mechanism is proposed. Given the support forces of the ground to the leg links, which can be obtained from the dynamic model, the spring forces of the legs and the impact resistance of each leg are the important parameters affecting buffering performance, and evaluation principles for buffering performance are proposed according to the aforementioned parameters. Based on the dynamic model and these evaluation principles, the buffering performances are analyzed and compared in different modes of landing and buffering on a horizontal plane and an inclined plane. The results show that the mechanism with the ends of the legs sliding can obtain a better dynamic performance. This study offers primary theories for buffering dynamics and an evaluation of landing buffer performance, and it establishes a theoretical basis for studies and engineering applications.

  17. Understanding the dynamic interactions driving Zambian health centre performance: a case-based health systems analysis

    PubMed Central

    Topp, Stephanie M; Chipukuma, Julien M; Hanefeld, Johanna

    2015-01-01

    Background Despite being central to achieving improved population health outcomes, primary health centres in low- and middle-income settings continue to underperform. Little research exists to adequately explain how and why this is the case. This study aimed to test the relevance and usefulness of an adapted conceptual framework for improving our understanding of the mechanisms and causal pathways influencing primary health centre performance. Methods A theory-driven, case-study approach was adopted. Four Zambian health centres were purposefully selected with case data including health-care worker interviews (n = 60); patient interviews (n = 180); direct observation of facility operations (2 weeks/centre) and key informant interviews (n = 14). Data were analysed to understand how the performance of each site was influenced by the dynamic interactions between system ‘hardware’ and ‘software’ acting on mechanisms of accountability. Findings Structural constraints including limited resources created challenging service environments in which work overload and stockouts were common. Health workers’ frustration with such conditions interacted with dissatisfaction with salary levels eroding service values and acting as a catalyst for different forms of absenteeism. Such behaviours exacerbated patient–provider ratios and increased the frequency of clinical and administrative shortcuts. Weak health information systems and lack of performance data undermined providers’ answerability to their employer and clients, and a lack of effective sanctions undermined supervisors’ ability to hold providers accountable for these transgressions. Weak answerability and enforceability contributed to a culture of impunity that masked and condoned weak service performance in all four sites. Conclusions Health centre performance is influenced by mechanisms of accountability, which are in turn shaped by dynamic interactions between system hardware and system software. Our

  18. Computational Analysis of Dynamic SPK(S8)-JP8 Fueled Combustor-Sector Performance

    NASA Technical Reports Server (NTRS)

    Ryder, R.; Hendricks, Roberts C.; Huber, M. L.; Shouse, D. T.

    2010-01-01

    Civil and military flight tests using blends of synthetic and biomass fueling with jet fuel up to 50:50 are currently considered as "drop-in" fuels. They are fully compatible with aircraft performance, emissions and fueling systems, yet the design and operations of such fueling systems and combustors must be capable of running fuels from a range of feedstock sources. This paper provides Smart Combustor or Fuel Flexible Combustor designers with computational tools, preliminary performance, emissions and particulates combustor sector data. The baseline fuel is kerosene-JP-8+100 (military) or Jet A (civil). Results for synthetic paraffinic kerosene (SPK) fuel blends show little change with respect to baseline performance, yet do show lower emissions. The evolution of a validated combustor design procedure is fundamental to the development of dynamic fueling of combustor systems for gas turbine engines that comply with multiple feedstock sources satisfying both new and legacy systems.

  19. Inlet-Compressor Analysis Performed Using Coupled Computational Fluid Dynamics Codes

    NASA Technical Reports Server (NTRS)

    Cole, Gary L.; Suresh, Ambady; Townsend, Scott

    1999-01-01

    A thorough understanding of dynamic interactions between inlets and compressors is extremely important to the design and development of propulsion control systems, particularly for supersonic aircraft such as the High-Speed Civil Transport (HSCT). Computational fluid dynamics (CFD) codes are routinely used to analyze individual propulsion components. By coupling the appropriate CFD component codes, it is possible to investigate inlet-compressor interactions. The objectives of this work were to gain a better understanding of inlet-compressor interaction physics, formulate a more realistic compressor-face boundary condition for time-accurate CFD simulations of inlets, and to take a first step toward the CFD simulation of an entire engine by coupling multidimensional component codes. This work was conducted at the NASA Lewis Research Center by a team of civil servants and support service contractors as part of the High Performance Computing and Communications Program (HPCCP).

  20. Performance Analysis of Garbage Collection and Dynamic Reordering in a Lisp System. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Llames, Rene Lim

    1991-01-01

    Generation based garbage collection and dynamic reordering of objects are two techniques for improving the efficiency of memory management in Lisp and similar dynamic language systems. An analysis of the effect of generation configuration is presented, focusing on the effect of a number of generations and generation capabilities. Analytic timing and survival models are used to represent garbage collection runtime and to derive structural results on its behavior. The survival model provides bounds on the age of objects surviving a garbage collection at a particular level. Empirical results show that execution time is most sensitive to the capacity of the youngest generation. A technique called scanning for transport statistics, for evaluating the effectiveness of reordering independent of main memory size, is presented.

  1. OSI Network-layer Abstraction: Analysis of Simulation Dynamics and Performance Indicators

    NASA Astrophysics Data System (ADS)

    Lawniczak, Anna T.; Gerisch, Alf; Di Stefano, Bruno

    2005-06-01

    The Open Systems Interconnection (OSI) reference model provides a conceptual framework for communication among computers in a data communication network. The Network Layer of this model is responsible for the routing and forwarding of packets of data. We investigate the OSI Network Layer and develop an abstraction suitable for the study of various network performance indicators, e.g. throughput, average packet delay, average packet speed, average packet path-length, etc. We investigate how the network dynamics and the network performance indicators are affected by various routing algorithms and by the addition of randomly generated links into a regular network connection topology of fixed size. We observe that the network dynamics is not simply the sum of effects resulting from adding individual links to the connection topology but rather is governed nonlinearly by the complex interactions caused by the existence of all randomly added and already existing links in the network. Data for our study was gathered using Netzwerk-1, a C++ simulation tool that we developed for our abstraction.

  2. Performance quantification of heliogyro solar sails using structural, attitude, and orbital dynamics and control analysis

    NASA Astrophysics Data System (ADS)

    Guerrant, Daniel Vernon

    Solar sails enable or enhance exploration of a variety of destinations both within and without the solar system. The heliogyro solar sail architecture divides the sail into blades spun about a central hub and centrifugally stiffened. The resulting structural mass savings can often double acceleration verses kite-type square sails of the same mass. Pitching the blades collectively and cyclically, similar to a helicopter, creates attitude control moments and vectors thrust. The principal hurdle preventing heliogyros' implementation is the uncertainty in their dynamics. This thesis investigates attitude, orbital and structural control using a combination of analytical studies and simulations. Furthermore, it quantifies the heliogyro's ability to create attitude control moments, change the thrust direction, and stably actuate blade pitch. This provides engineers a toolbox from which to estimate the heliogyro's performance and perform trades during preliminary mission design. It is shown that heliogyros can create an attitude control moment in any direction from any orientation. While their large angular momentum limits attitude slewing to only a few degrees per hour, cyclic blade pitching can slew the thrust vector within a few minutes. This approach is only 13% less efficient than slewing a square sail during Earth escape, so it does not offset the overall acceleration benefits of heliogyros. Lastly, a root pitch motor should be able to settle torsional disturbances within a few rotations and achieve thrust performance comparable to that of flat blades. This work found no significant dynamic hurdles for heliogyros, and it provides key insight into their practical capabilities and limitations for future mission designers.

  3. Dynamic analysis and performance evaluation of the BIAcore surface plasmon resonance biosensor

    NASA Astrophysics Data System (ADS)

    Simon, Laurent; Ospina, Juan

    2015-05-01

    Solution procedures were proposed to analyze nonlinear mass transport through an optical biosensor. A generalized collocation technique was applied to predict the dynamic behavior of an analyte along the flow chamber as a result of convection, diffusion and chemical reaction. The method estimated the effective time constants for reaching average steady-state concentrations of the free and bound analytes in the cell. When diffusion in the direction of flow was neglected, a closed-form solution, based on double Laplace transforms, was obtained after linearizing the original system. In both models, an increase in the sample diffusion coefficient lowered the effective time constant. This approach may help researchers evaluate the performance of biosensors and meet specific design criteria.

  4. Analysis of the effect of swimmer's head position on swimming performance using computational fluid dynamics.

    PubMed

    Zaïdi, H; Taïar, R; Fohanno, S; Polidori, G

    2008-01-01

    The aim of this numerical work is to analyze the effect of the position of the swimmer's head on the hydrodynamic performances in swimming. In this initial study, the problem was modeled as 2D and in steady hydrodynamic state. The geometry is generated by the CAD software CATIA and the numerical simulation is carried out by the use of the CFD Fluent code. The standard k-epsilon turbulence model is used with a specific wall law. Three positions of the head were studied, for a range of Reynolds numbers about 10(6). The obtained numerical results revealed that the position of the head had a noticeable effect on the hydrodynamic performances, strongly modifying the wake around the swimmer. The analysis of these results made it possible to propose an optimal position of the head of a swimmer in underwater swimming. PMID:18374343

  5. Improved Dynamic Modeling of the Cascade Distillation Subsystem and Analysis of Factors Affecting Its Performance

    NASA Technical Reports Server (NTRS)

    Perry, Bruce A.; Anderson, Molly S.

    2015-01-01

    The Cascade Distillation Subsystem (CDS) is a rotary multistage distiller being developed to serve as the primary processor for wastewater recovery during long-duration space missions. The CDS could be integrated with a system similar to the International Space Station Water Processor Assembly to form a complete water recovery system for future missions. A preliminary chemical process simulation was previously developed using Aspen Custom Modeler® (ACM), but it could not simulate thermal startup and lacked detailed analysis of several key internal processes, including heat transfer between stages. This paper describes modifications to the ACM simulation of the CDS that improve its capabilities and the accuracy of its predictions. Notably, the modified version can be used to model thermal startup and predicts the total energy consumption of the CDS. The simulation has been validated for both NaC1 solution and pretreated urine feeds and no longer requires retuning when operating parameters change. The simulation was also used to predict how internal processes and operating conditions of the CDS affect its performance. In particular, it is shown that the coefficient of performance of the thermoelectric heat pump used to provide heating and cooling for the CDS is the largest factor in determining CDS efficiency. Intrastage heat transfer affects CDS performance indirectly through effects on the coefficient of performance.

  6. Dynamical analysis and performance evaluation of a biped robot under multi-source random disturbances

    NASA Astrophysics Data System (ADS)

    Gan, Chun-Biao; Ding, Chang-Tao; Yang, Shi-Xi

    2014-12-01

    During bipedal walking, it is critical to detect and adjust the robot postures by feedback control to maintain its normal state amidst multi-source random disturbances arising from some unavoidable uncertain factors. The radical basis function (RBF) neural network model of a five-link biped robot is established, and two certain disturbances and a randomly uncertain disturbance are then mixed with the optimal torques in the network model to study the performance of the biped robot by several evaluation indices and a specific Poincaré map. In contrast with the simulations, the response varies as desired under optimal inputting while the output is fluctuating in the situation of disturbance driving. Simulation results from noise inputting also show that the dynamics of the robot is less sensitive to the disturbance of knee joint input of the swing leg than those of the other three joints, the response errors of the biped will be increasing with higher disturbance levels, and especially there are larger output fluctuations in the knee and hip joints of the swing leg.

  7. Threshold-based queuing system for performance analysis of cloud computing system with dynamic scaling

    SciTech Connect

    Shorgin, Sergey Ya.; Pechinkin, Alexander V.; Samouylov, Konstantin E.; Gaidamaka, Yuliya V.; Gudkova, Irina A.; Sopin, Eduard S.

    2015-03-10

    Cloud computing is promising technology to manage and improve utilization of computing center resources to deliver various computing and IT services. For the purpose of energy saving there is no need to unnecessarily operate many servers under light loads, and they are switched off. On the other hand, some servers should be switched on in heavy load cases to prevent very long delays. Thus, waiting times and system operating cost can be maintained on acceptable level by dynamically adding or removing servers. One more fact that should be taken into account is significant server setup costs and activation times. For better energy efficiency, cloud computing system should not react on instantaneous increase or instantaneous decrease of load. That is the main motivation for using queuing systems with hysteresis for cloud computing system modelling. In the paper, we provide a model of cloud computing system in terms of multiple server threshold-based infinite capacity queuing system with hysteresis and noninstantanuous server activation. For proposed model, we develop a method for computing steady-state probabilities that allow to estimate a number of performance measures.

  8. Atomistic Molecular Dynamics Simulations of DNA Minicircle Topoisomers: A Practical Guide to Setup, Performance, and Analysis.

    PubMed

    Sutthibutpong, Thana; Noy, Agnes; Harris, Sarah

    2016-01-01

    While DNA supercoiling is ubiquitous in vivo, the structure of supercoiled DNA is more challenging to study experimentally than simple linear sequences because the DNA must have a closed topology in order to sustain superhelical stress. DNA minicircles, which are closed circular double-stranded DNA sequences typically containing between 60 and 500 base pairs, have proven to be useful biochemical tools for the study of supercoiled DNA mechanics. We present detailed protocols for constructing models of DNA minicircles in silico, for performing atomistic molecular dynamics (MD) simulations of supercoiled minicircle DNA, and for analyzing the results of the calculations. These simulations are computationally challenging due to the large system sizes. However, improvements in parallel computing software and hardware promise access to improve conformational sampling and simulation timescales. Given the concurrent improvements in the resolution of experimental techniques such as atomic force microscopy (AFM) and cryo-electron microscopy, the study of DNA minicircles will provide a more complete understanding of both the structure and the mechanics of supercoiled DNA. PMID:27283311

  9. Analysis of dynamic interaction between catenary and pantograph with experimental verification and performance evaluation in new high-speed line

    NASA Astrophysics Data System (ADS)

    Lee, Jin Hee; Park, Tae Won; Oh, Hyuck Keun; Kim, Young Guk

    2015-08-01

    Understanding the dynamic interaction between the catenary and pantograph of a high-speed train is the one of the most important technical issues in the railway industry. This is because the catenary-pantograph system plays a crucial role in providing electric power to the railway vehicle for stable operation. The aim of the present paper is to estimate the current-collection performance of this system by using numerical analysis, in particular, the flexible multibody dynamic analysis technique. To implement large deformable catenary wires, an absolute nodal coordinate formulation is used for the cable element. Additionally, an efficient contact element and an interactive model for the catenary-pantograph system are introduced. Each developed model is then used for analytical and experimental verification. Actual on-line test results of existing high-speed railway vehicles are presented and used to verify the analysis model. Finally, the performance characteristics of a new 400 km/h-class high-speed line are estimated and evaluated on the basis of international standards.

  10. Finite element analysis of thermal distortion effects on optical performance of solar dynamic concentrator for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Doherty, Michael P.; Dalsania, Vithal

    1990-01-01

    An analysis was performed to predict the thermal distortion of the solar dynamic concentrator for Space Station Freedom in low earth orbit and to evaluate the effects of that thermal distortion on concentrator on-orbit performance. The analysis required substructural finite element modeling of critical concentrator structural subsystems, structural finite element modeling of the concentrator, mapping of thermal loading onto the structural finite element model, and the creation of specialized postprocessors to assist in interpreting results. Concentrator temperature distributions and thermally induced displacements and slope errors and the resulting receiver flux distribution profiles are discussed. Results determined for a typical orbit indicate that concentrator facet rotations are less than 0.2 mrad and that the change in facet radius due to thermal flattening is less than 5 percent. The predicted power loss due to thermal distortion effects is less than 0.3 percent. As a consequence the thermal distortions of the solar dynamic concentrator in low earth orbit will have a negligible effect on the flux distribution profiles within the receiver.

  11. Modeling and analysis of transient vehicle underhood thermo- hydrodynamic events using computational fluid dynamics and high performance computing.

    SciTech Connect

    Tentner, A.; Froehle, P.; Wang, C.; Nuclear Engineering Division

    2004-01-01

    This work has explored the preliminary design of a Computational Fluid Dynamics (CFD) tool for the analysis of transient vehicle underhood thermo-hydrodynamic events using high performance computing platforms. The goal of this tool will be to extend the capabilities of an existing established CFD code, STAR-CD, allowing the car manufacturers to analyze the impact of transient operational events on the underhood thermal management by exploiting the computational efficiency of modern high performance computing systems. In particular, the project has focused on the CFD modeling of the radiator behavior during a specified transient. The 3-D radiator calculations were performed using STAR-CD, which can perform both steady-state and transient calculations, on the cluster computer available at ANL in the Nuclear Engineering Division. Specified transient boundary conditions, based on experimental data provided by Adapco and DaimlerChrysler were used. The possibility of using STAR-CD in a transient mode for the entire period of time analyzed has been compared with other strategies which involve the use of STAR-CD in a steady-state mode at specified time intervals, while transient heat transfer calculations would be performed for the rest of the time. The results of these calculations have been compared with the experimental data provided by Adapco/DaimlerChrysler and recommendations for future development of an optimal strategy for the CFD modeling of transient thermo-hydrodynamic events have been made. The results of this work open the way for the development of a CFD tool for the transient analysis of underhood thermo-hydrodynamic events, which will allow the integrated transient thermal analysis of the entire cooling system, including both the engine block and the radiator, on high performance computing systems.

  12. Modeling and analysis of transient vehicle underhood thermo - hydrodynamic events using computational fluid dynamics and high performance computing.

    SciTech Connect

    Froehle, P.; Tentner, A.; Wang, C.

    2003-09-05

    This work has explored the preliminary design of a Computational Fluid Dynamics (CFD) tool for the analysis of transient vehicle underhood thermo-hydrodynamic events using high performance computing platforms. The goal of this tool will be to extend the capabilities of an existing established CFD code, STAR-CD, allowing the car manufacturers to analyze the impact of transient operational events on the underhood thermal management by exploiting the computational efficiency of modern high performance computing systems. In particular, the project has focused on the CFD modeling of the radiator behavior during a specified transient. The 3-D radiator calculations were performed using STAR-CD, which can perform both steady-state and transient calculations, on the cluster computer available at ANL in the Nuclear Engineering Division. Specified transient boundary conditions, based on experimental data provided by Adapco and DaimlerChrysler were used. The possibility of using STAR-CD in a transient mode for the entire period of time analyzed has been compared with other strategies which involve the use of STAR-CD in a steady-state mode at specified time intervals, while transient heat transfer calculations would be performed for the rest of the time. The results of these calculations have been compared with the experimental data provided by Adapco/DaimlerChrysler and recommendations for future development of an optimal strategy for the CFD modeling of transient thermo-hydrodynamic events have been made. The results of this work open the way for the development of a CFD tool for the transient analysis of underhood thermo-hydrodynamic events, which will allow the integrated transient thermal analysis of the entire cooling system, including both the engine block and the radiator, on high performance computing systems.

  13. Job Performance as Multivariate Dynamic Criteria: Experience Sampling and Multiway Component Analysis

    ERIC Educational Resources Information Center

    Spain, Seth M.; Miner, Andrew G.; Kroonenberg, Pieter M.; Drasgow, Fritz

    2010-01-01

    Questions about the dynamic processes that drive behavior at work have been the focus of increasing attention in recent years. Models describing behavior at work and research on momentary behavior indicate that substantial variation exists within individuals. This article examines the rationale behind this body of work and explores a method of…

  14. HAWT performance with dynamic stall

    NASA Astrophysics Data System (ADS)

    Hibbs, B. D.

    1986-02-01

    The effects of flow nonuniformities (wing shear, tower wake, yaw, and large-scale turbulence) on the performance of a horizontal axis wind turbine are calculated, accounting for dynamic stall. The PROP program was modified to incorporate and compare these effects with the uniform flow case. The MIT model, which predicts dynamic lift coefficients substantially higher than the static maximum values and includes a crude model of the vortex roll-off phenomenon, represented dynamic stall. As associated model for drag was also used. The dynamic stall model was tested against experimental data for three typical reduced frequencies. Good instantaneous correlation was obtained. The effects of nonuniformities with and without the dynamic stall were calculated using the Westinghouse Mod O and Enertech 44/25 turbines. Modeling the dynamic stall has little effect on performance. Furthermore, the performance with nonuniform flow differed only slightly from the uniform flow case. Thus the new PROP model provides a powerful general capability to handle nonuniform flows.

  15. Team performance and collective efficacy in the dynamic psychology of competitive team: a Bayesian network analysis.

    PubMed

    Fuster-Parra, P; García-Mas, A; Ponseti, F J; Leo, F M

    2015-04-01

    The purpose of this paper was to discover the relationships among 22 relevant psychological features in semi-professional football players in order to study team's performance and collective efficacy via a Bayesian network (BN). The paper includes optimization of team's performance and collective efficacy using intercausal reasoning pattern which constitutes a very common pattern in human reasoning. The BN is used to make inferences regarding our problem, and therefore we obtain some conclusions; among them: maximizing the team's performance causes a decrease in collective efficacy and when team's performance achieves the minimum value it causes an increase in moderate/high values of collective efficacy. Similarly, we may reason optimizing team collective efficacy instead. It also allows us to determine the features that have the strongest influence on performance and which on collective efficacy. From the BN two different coaching styles were differentiated taking into account the local Markov property: training leadership and autocratic leadership. PMID:25546263

  16. Information Systems, Competitive Dynamics, and Firm Performance: An Interpretive and Centering Resonance Analysis

    ERIC Educational Resources Information Center

    Vannoy, Sandra A.

    2010-01-01

    This dissertation examines, from a managerial interpretive perspective, how information systems contribute to firms' specific competitive actions and responses, and the resultant impacts upon firm performance. The findings from this research suggest that the answer may well lie within the role of information systems in firms' competitive dynamics…

  17. Confinement Vessel Dynamic Analysis

    SciTech Connect

    R. Robert Stevens; Stephen P. Rojas

    1999-08-01

    A series of hydrodynamic and structural analyses of a spherical confinement vessel has been performed. The analyses used a hydrodynamic code to estimate the dynamic blast pressures at the vessel's internal surfaces caused by the detonation of a mass of high explosive, then used those blast pressures as applied loads in an explicit finite element model to simulate the vessel's structural response. Numerous load cases were considered. Particular attention was paid to the bolted port connections and the O-ring pressure seals. The analysis methods and results are discussed, and comparisons to experimental results are made.

  18. Communication Range Dynamics and Performance Analysis for a Self-Adaptive Transmission Power Controller.

    PubMed

    Lucas Martínez, Néstor; Martínez Ortega, José-Fernán; Hernández Díaz, Vicente; Del Toro Matamoros, Raúl M

    2016-01-01

    The deployment of the nodes in a Wireless Sensor and Actuator Network (WSAN) is typically restricted by the sensing and acting coverage. This implies that the locations of the nodes may be, and usually are, not optimal from the point of view of the radio communication. Additionally, when the transmission power is tuned for those locations, there are other unpredictable factors that can cause connectivity failures, like interferences, signal fading due to passing objects and, of course, radio irregularities. A control-based self-adaptive system is a typical solution to improve the energy consumption while keeping good connectivity. In this paper, we explore how the communication range for each node evolves along the iterations of an energy saving self-adaptive transmission power controller when using different parameter sets in an outdoor scenario, providing a WSAN that automatically adapts to surrounding changes keeping good connectivity. The results obtained in this paper show how the parameters with the best performance keep a k-connected network, where k is in the range of the desired node degree plus or minus a specified tolerance value. PMID:27187397

  19. Communication Range Dynamics and Performance Analysis for a Self-Adaptive Transmission Power Controller †

    PubMed Central

    Lucas Martínez, Néstor; Martínez Ortega, José-Fernán; Hernández Díaz, Vicente; del Toro Matamoros, Raúl M.

    2016-01-01

    The deployment of the nodes in a Wireless Sensor and Actuator Network (WSAN) is typically restricted by the sensing and acting coverage. This implies that the locations of the nodes may be, and usually are, not optimal from the point of view of the radio communication. Additionally, when the transmission power is tuned for those locations, there are other unpredictable factors that can cause connectivity failures, like interferences, signal fading due to passing objects and, of course, radio irregularities. A control-based self-adaptive system is a typical solution to improve the energy consumption while keeping good connectivity. In this paper, we explore how the communication range for each node evolves along the iterations of an energy saving self-adaptive transmission power controller when using different parameter sets in an outdoor scenario, providing a WSAN that automatically adapts to surrounding changes keeping good connectivity. The results obtained in this paper show how the parameters with the best performance keep a k-connected network, where k is in the range of the desired node degree plus or minus a specified tolerance value. PMID:27187397

  20. HAWT performance with dynamic stall

    SciTech Connect

    Hibbs, B.D.

    1986-02-01

    In this report we calculated the effects of flow nonuniformities (wing shear, tower wake, yaw, and large-scale turbulence) on the performance of a horizontal axis wind turbine, accounting for dynamic stall. We modified the PROP program to incorporate and compare these effects with the uniform flow case. The MIT model, which predicts dynamic lift coefficients substantially higher than the static maximum values and includes a crude model of the vortex roll-off phenomenon, represented dynamic stall. As associated model for drag was also used. The dynamic stall model was tested against experimental data for three typical reduced frequencies. Good instantaneous correlation was obtained. The effects of nonuniformities with and without the dynamic stall were calculated using the Westinghouse Mod O and Enertech 44/25 turbines. Modeling the dynamic stall has little effect on performance. Furthermore, the performance with nonuniform flow differed only slightly from the uniform flow case. Thus the now PROP model provides a powerful general capability to handle nonuniform flows.

  1. Flight Dynamics Analysis Branch

    NASA Technical Reports Server (NTRS)

    Stengle, Tom; Flores-Amaya, Felipe

    2000-01-01

    This report summarizes the major activities and accomplishments carried out by the Flight Dynamics Analysis Branch (FDAB), Code 572, in support of flight projects and technology development initiatives in fiscal year 2000. The report is intended to serve as a summary of the type of support carried out by the FDAB, as well as a concise reference of key accomplishments and mission experience derived from the various mission support roles. The primary focus of the FDAB is to provide expertise in the disciplines of flight dynamics, spacecraft trajectory, attitude analysis, and attitude determination and control. The FDAB currently provides support for missions and technology development projects involving NASA, government, university, and private industry.

  2. Computational fluid dynamics analysis of blade tip clearances on hemodynamic performance and blood damage in a centrifugal ventricular assist device.

    PubMed

    Wu, Jingchun; Paden, Bradley E; Borovetz, Harvey S; Antaki, James F

    2010-05-01

    An important challenge facing the design of turbodynamic ventricular assist devices (VADs) intended for long-term support is the optimization of the flow path geometry to maximize hydraulic performance while minimizing shear-stress-induced hemolysis and thrombosis. For unshrouded centrifugal, mixed-flow and axial-flow blood pumps, the complex flow patterns within the blade tip clearance between the lengthwise upper surface of the rotating impeller blades and the stationary pump housing have a dramatic effect on both the hydrodynamic performance and the blood damage production. Detailed computational fluid dynamics (CFD) analyses were performed in this study to investigate such flow behavior in blade tip clearance region for a centrifugal blood pump representing a scaled-up version of a prototype pediatric VAD. Nominal flow conditions were analyzed at a flow rate of 2.5 L/min and rotor speed of 3000 rpm with three blade tip clearances of 50, 100, and 200 microm. CFD simulations predicted a decrease in the averaged tip leakage flow rate and an increase in pump head and axial thrust with decreasing blade tip clearances from 200 to 50 microm. The predicted hemolysis, however, exhibited a unimodal relationship, having a minimum at 100 microm compared to 50 microm and 200 microm. Experimental data corroborate these predictions. Detailed flow patterns observed in this study revealed interesting fluid dynamic features associated with the blade tip clearances, such as the generation and dissipation of tip leakage vortex and its interaction with the primary flow in the blade-blade passages. Quantitative calculations suggested the existence of an optimal blade tip clearance by which hydraulic efficiency can be maximized and hemolysis minimized. PMID:19832736

  3. Computational Fluid Dynamics Analysis of Blade Tip Clearances on Hemodynamic Performance and Blood Damage in a Centrifugal Ventricular Assist Device

    PubMed Central

    Wu, Jingchun; Paden, Bradley E.; Borovetz, Harvey S.; Antaki, James F.

    2011-01-01

    An important challenge facing the design of turbodynamic ventricular assist devices (VADs) intended for long-term support is the optimization of the flow path geometry to maximize hydraulic performance while minimizing shear-stress-induced hemolysis and thrombosis. For unshrouded centrifugal, mixed-flow and axial-flow blood pumps, the complex flow patterns within the blade tip clearance between the lengthwise upper surface of the rotating impeller blades and the stationary pump housing have a dramatic effect on both the hydrodynamic performance and the blood damage production. Detailed computational fluid dynamics (CFD) analyses were performed in this study to investigate such flow behavior in blade tip clearance region for a centrifugal blood pump representing a scaled-up version of a prototype pediatric VAD. Nominal flow conditions were analyzed at a flow rate of 2.5 L/min and rotor speed of 3000 rpm with three blade tip clearances of 50, 100, and 200 μm. CFD simulations predicted a decrease in the averaged tip leakage flow rate and an increase in pump head and axial thrust with decreasing blade tip clearances from 200 to 50 μm. The predicted hemolysis, however, exhibited a unimodal relationship, having a minimum at 100 μm compared to 50 μm and 200 μm. Experimental data corroborate these predictions. Detailed flow patterns observed in this study revealed interesting fluid dynamic features associated with the blade tip clearances, such as the generation and dissipation of tip leakage vortex and its interaction with the primary flow in the blade-blade passages. Quantitative calculations suggested the existence of an optimal blade tip clearance by which hydraulic efficiency can be maximized and hemolysis minimized. PMID:19832736

  4. Computational fluid dynamics analysis of cyclist aerodynamics: performance of different turbulence-modelling and boundary-layer modelling approaches.

    PubMed

    Defraeye, Thijs; Blocken, Bert; Koninckx, Erwin; Hespel, Peter; Carmeliet, Jan

    2010-08-26

    This study aims at assessing the accuracy of computational fluid dynamics (CFD) for applications in sports aerodynamics, for example for drag predictions of swimmers, cyclists or skiers, by evaluating the applied numerical modelling techniques by means of detailed validation experiments. In this study, a wind-tunnel experiment on a scale model of a cyclist (scale 1:2) is presented. Apart from three-component forces and moments, also high-resolution surface pressure measurements on the scale model's surface, i.e. at 115 locations, are performed to provide detailed information on the flow field. These data are used to compare the performance of different turbulence-modelling techniques, such as steady Reynolds-averaged Navier-Stokes (RANS), with several k-epsilon and k-omega turbulence models, and unsteady large-eddy simulation (LES), and also boundary-layer modelling techniques, namely wall functions and low-Reynolds number modelling (LRNM). The commercial CFD code Fluent 6.3 is used for the simulations. The RANS shear-stress transport (SST) k-omega model shows the best overall performance, followed by the more computationally expensive LES. Furthermore, LRNM is clearly preferred over wall functions to model the boundary layer. This study showed that there are more accurate alternatives for evaluating flow around bluff bodies with CFD than the standard k-epsilon model combined with wall functions, which is often used in CFD studies in sports. PMID:20488446

  5. Analysis of the gas-dynamic performance of a vaned diffuser with given velocity distribution along the vane's surfaces

    NASA Astrophysics Data System (ADS)

    Kalinkevych, M.; Obukhov, O.; Obukhova, O.; Miroshnychenko, A.

    2015-08-01

    Extension of the effective range of vaned diffusers is one of the promising ways to improve the centrifugal compressor's stages which are used in numerous fields of industry. The new method of profiling of the diffuser vanes has been developed using Stratford's results and boundary layer theory by Loytsanskiy. The developed method is based on the solution of the inverse task of gas-dynamic using given velocity distribution along the vane's surface. Comparison of the results of numerical simulations for different diffusers has shown that the performance of the diffuser designed with the resulting velocity distribution are better. Influence of the vane profile, number of the vanes, diffuser outlet diameter and the diffuser width on diffuser characteristics has been investigated. The results of the simulations have been used to formulate recommendations on the design of high-effectiveness vaned diffusers for centrifugal stages of different types.

  6. Performance Measurement Analysis System

    Energy Science and Technology Software Center (ESTSC)

    1989-06-01

    The PMAS4.0 (Performance Measurement Analysis System) is a user-oriented system designed to track the cost and schedule performance of Department of Energy (DOE) major projects (MPs) and major system acquisitions (MSAs) reporting under DOE Order 5700.4A, Project Management System. PMAS4.0 provides for the analysis of performance measurement data produced from management control systems complying with the Federal Government''s Cost and Schedule Control Systems Criteria.

  7. Ariel Performance Analysis System

    NASA Astrophysics Data System (ADS)

    Ariel, Gideon B.; Penny, M. A.; Saar, Dany

    1990-08-01

    The Ariel Performance Analysis System is a computer-based system for the measurement, analysis and presentation of human performance. The system is based on a proprietary technique for processing multiple high-speed film and video recordings of a subject's performance. It is noninvasive, and does not require wires, sensors, markers or reflectors. In addition, it is portable and does not require modification of the performing environment. The scale and accuracy of measurement can be set to whatever levels are required by the activity being performed.

  8. Motorcycle dynamics by multibody dynamics analysis

    SciTech Connect

    Imaizumi, Hirohide; Fujioka, Takehiko

    1995-12-31

    The purpose of this paper is to construct simulation models of a motorcycle with a rider by use of multibody dynamics analysis (MDA). Three types of MDA models are developed for evaluation of the effectiveness of MDA for motorcycle dynamics. Impulse responses with parameter study and lane change maneuvers are calculated. The results of simulations agree with that of experiments well and effectiveness of MDA to the motorcycle dynamics field is shown.

  9. A Sit-to-Stand Training Robot and Its Performance Evaluation: Dynamic Analysis in Lower Limb Rehabilitation Activities

    NASA Astrophysics Data System (ADS)

    Cao, Enguo; Inoue, Yoshio; Liu, Tao; Shibata, Kyoko

    In many countries in which the phenomenon of population aging is being experienced, motor function recovery activities have aroused much interest. In this paper, a sit-to-stand rehabilitation robot utilizing a double-rope system was developed, and the performance of the robot was evaluated by analyzing the dynamic parameters of human lower limbs. For the robot control program, an impedance control method with a training game was developed to increase the effectiveness and frequency of rehabilitation activities, and a calculation method was developed for evaluating the joint moments of hip, knee, and ankle. Test experiments were designed, and four subjects were requested to stand up from a chair with assistance from the rehabilitation robot. In the experiments, body segment rotational angles, trunk movement trajectories, rope tensile forces, ground reaction forces (GRF) and centers of pressure (COP) were measured by sensors, and the moments of ankle, knee and hip joint were real-time calculated using the sensor-measured data. The experiment results showed that the sit-to-stand rehabilitation robot with impedance control method could maintain the comfortable training postures of users, decrease the moments of limb joints, and enhance training effectiveness. Furthermore, the game control method could encourage collaboration between the brain and limbs, and allow for an increase in the frequency and intensity of rehabilitation activities.

  10. Performance Support for Performance Analysis

    ERIC Educational Resources Information Center

    Schaffer, Scott; Douglas, Ian

    2004-01-01

    Over the past several years, there has been a shift in emphasis in many business, industry, government and military training organizations toward human performance technology or HPT (Rossett, 2002; Dean, 1995). This trend has required organizations to increase the human performance knowledge, skills, and abilities of the training workforce.…

  11. High performance computations using dynamical nucleation theory

    NASA Astrophysics Data System (ADS)

    Windus, T. L.; Kathmann, S. M.; Crosby, L. D.

    2008-07-01

    Chemists continue to explore the use of very large computations to perform simulations that describe the molecular level physics of critical challenges in science. In this paper, we describe the Dynamical Nucleation Theory Monte Carlo (DNTMC) model - a model for determining molecular scale nucleation rate constants - and its parallel capabilities. The potential for bottlenecks and the challenges to running on future petascale or larger resources are delineated. A 'master-slave' solution is proposed to scale to the petascale and will be developed in the NWChem software. In addition, mathematical and data analysis challenges are described.

  12. Flexible rotor dynamics analysis

    NASA Technical Reports Server (NTRS)

    Shen, F. A.

    1973-01-01

    A digital computer program was developed to analyze the general nonaxisymmetric and nonsynchronous transient and steady-state rotor dynamic performance of a bending- and shear-wise flexible rotor-bearing system under various operating conditions. The effects of rotor material mechanical hysteresis, rotor torsion flexibility, transverse effects of rotor axial and torsional loading and the anisotropic, in-phase and out-of-phase bearing stiffness and damping force and moment coefficients were included in the program to broaden its capability. An optimum solution method was found and incorporated in the computer program. Computer simulation of experimental data was made and qualitative agreements observed. The mathematical formulations, computer program verification, test data simulation, and user instruction was presented and discussed.

  13. Dynamical analysis of anisotropic inflation

    NASA Astrophysics Data System (ADS)

    Karčiauskas, Mindaugas

    2016-06-01

    The inflaton coupling to a vector field via the f(φ)2F μνFμν term is used in several contexts in the literature, such as to generate primordial magnetic fields, to produce statistically anisotropic curvature perturbation, to support anisotropic inflation, and to circumvent the η-problem. In this work, I perform dynamical analysis of this system allowing for the most general Bianchi I initial conditions. I also confirm the stability of attractor fixed points along phase-space directions that had not been investigated before.

  14. Stage Separation Performance Analysis Project

    NASA Technical Reports Server (NTRS)

    Chen, Yen-Sen; Zhang, Sijun; Liu, Jiwen; Wang, Ten-See

    2001-01-01

    Stage separation process is an important phenomenon in multi-stage launch vehicle operation. The transient flowfield coupled with the multi-body systems is a challenging problem in design analysis. The thermodynamics environment with burning propellants during the upper-stage engine start in the separation processes adds to the complexity of the-entire system. Understanding the underlying flow physics and vehicle dynamics during stage separation is required in designing a multi-stage launch vehicle with good flight performance. A computational fluid dynamics model with the capability to coupling transient multi-body dynamics systems will be a useful tool for simulating the effects of transient flowfield, plume/jet heating and vehicle dynamics. A computational model using generalize mesh system will be used as the basis of this development. The multi-body dynamics system will be solved, by integrating a system of six-degree-of-freedom equations of motion with high accuracy. Multi-body mesh system and their interactions will be modeled using parallel computing algorithms. Adaptive mesh refinement method will also be employed to enhance solution accuracy in the transient process.

  15. Session 6: Dynamic Modeling and Systems Analysis

    NASA Technical Reports Server (NTRS)

    Csank, Jeffrey; Chapman, Jeffryes; May, Ryan

    2013-01-01

    These presentations cover some of the ongoing work in dynamic modeling and dynamic systems analysis. The first presentation discusses dynamic systems analysis and how to integrate dynamic performance information into the systems analysis. The ability to evaluate the dynamic performance of an engine design may allow tradeoffs between the dynamic performance and operability of a design resulting in a more efficient engine design. The second presentation discusses the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS). T-MATS is a Simulation system with a library containing the basic building blocks that can be used to create dynamic Thermodynamic Systems. Some of the key features include Turbo machinery components, such as turbines, compressors, etc., and basic control system blocks. T-MAT is written in the Matlab-Simulink environment and is open source software. The third presentation focuses on getting additional performance from the engine by allowing the limit regulators only to be active when a limit is danger of being violated. Typical aircraft engine control architecture is based on MINMAX scheme, which is designed to keep engine operating within prescribed mechanical/operational safety limits. Using a conditionally active min-max limit regulator scheme, additional performance can be gained by disabling non-relevant limit regulators

  16. Dynamic analysis for the global performance of an SPM-feeder-cage system under waves and currents

    NASA Astrophysics Data System (ADS)

    Cifuentes, Cristian; Kim, M. H.

    2015-06-01

    In the present study, the dynamic response of a coupled SPM-feeder-cage system under irregular waves and shear currents is analyzed. A numerical model is developed by using the commercial software OrcaFlex. Hydrodynamics coefficients of the vessel are calculated by using a 3D diffraction/radiation panel program. First- and second-order wave forces are included in the calculations. Morison equation is used to compute the drag force on line elements representing the net. Drag coefficients are determined at every time step in the simulation considering the relative normal velocity between the structural elements and the fluid flow. The dynamic response of the coupled system is analyzed for various environments and net materials. The results of the study show the effects of solidity ratio of the net and vertical positions of the cage on the overall dynamic response of the system, confirming the viability of this type of configuration for future development of offshore aquaculture in deep waters.

  17. MIR Performance Analysis

    SciTech Connect

    Hazen, Damian; Hick, Jason

    2012-06-12

    We provide analysis of Oracle StorageTek T10000 Generation B (T10KB) Media Information Record (MIR) Performance Data gathered over the course of a year from our production High Performance Storage System (HPSS). The analysis shows information in the MIR may be used to improve tape subsystem operations. Most notably, we found the MIR information to be helpful in determining whether the drive or tape was most suspect given a read or write error, and for helping identify which tapes should not be reused given their history of read or write errors. We also explored using the MIR Assisted Search to order file retrieval requests. We found that MIR Assisted Search may be used to reduce the time needed to retrieve collections of files from a tape volume.

  18. High performance computations using dynamical nucleation theory

    SciTech Connect

    Windus, Theresa L.; Kathmann, Shawn M.; Crosby, Lonnie D.

    2008-07-14

    Chemists continue to explore the use of very large computations to perform simulations that describe the molecular level physics of critical challenges in science. In this paper, the Dynamical Nucleation Theory Monte Carlo (DNTMC) model - a model for determining molecular scale nucleation rate constants - and its parallel capabilities are described. The potential for bottlenecks and the challenges to running on future petascale or larger resources are delineated. A "master-slave" solution is proposed to scale to the petascale and will be developed in the NWChem software. In addition, mathematical and data analysis challenges are also described. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

  19. Do the Dynamics of Prior Information Depend on Task Context? An Analysis of Optimal Performance and an Empirical Test

    PubMed Central

    van Ravenzwaaij, Don; Mulder, Martijn J.; Tuerlinckx, Francis; Wagenmakers, Eric-Jan

    2012-01-01

    In speeded two-choice tasks, optimal performance is prescribed by the drift diffusion model. In this model, prior information or advance knowledge about the correct response can manifest itself as a shift in starting point or as a shift in drift rate criterion. These two mechanisms lead to qualitatively different choice behavior. Analyses of optimal performance (i.e., Bogacz et al., 2006; Hanks et al., 2011) have suggested that bias should manifest itself in starting point when difficulty is fixed over trials, whereas bias should (additionally) manifest itself in drift rate criterion when difficulty is variable over trials. In this article, we challenge the claim that a shift in drift criterion is necessary to perform optimally in a biased decision environment with variable stimulus difficulty. This paper consists of two parts. Firstly, we demonstrate that optimal behavior for biased decision problems is prescribed by a shift in starting point, irrespective of variability in stimulus difficulty. Secondly, we present empirical data which show that decision makers do not adopt different strategies when dealing with bias in conditions of fixed or variable across-trial stimulus difficulty. We also perform a test of specific influence for drift rate variability. PMID:22615704

  20. New paradigm for task switching strategies while performing multiple tasks: entropy and symbolic dynamics analysis of voluntary patterns.

    PubMed

    Guastello, Stephen J; Gorin, Hillary; Huschen, Samuel; Peters, Natalie E; Fabisch, Megan; Poston, Kirsten

    2012-10-01

    It has become well established in laboratory experiments that switching tasks, perhaps due to interruptions at work, incur costs in response time to complete the next task. Conditions are also known that exaggerate or lessen the switching costs. Although switching costs can contribute to fatigue, task switching can also be an adaptive response to fatigue. The present study introduces a new research paradigm for studying the emergence of voluntary task switching regimes, self-organizing processes therein, and the possibly conflicting roles of switching costs and minimum entropy. Fifty-four undergraduates performed 7 different computer-based cognitive tasks producing sets of 49 responses under instructional conditions requiring task quotas or no quotas. The sequences of task choices were analyzed using orbital decomposition to extract pattern types and lengths, which were then classified and compared with regard to Shannon entropy, topological entropy, number of task switches involved, and overall performance. Results indicated that similar but different patterns were generated under the two instructional conditions, and better performance was associated with lower topological entropy. Both entropy metrics were associated with the amount of voluntary task switching. Future research should explore conditions affecting the trade-off between switching costs and entropy, levels of automaticity between task elements, and the role of voluntary switching regimes on fatigue. PMID:22980455

  1. Nonlinear analysis of pupillary dynamics.

    PubMed

    Onorati, Francesco; Mainardi, Luca Tommaso; Sirca, Fabiola; Russo, Vincenzo; Barbieri, Riccardo

    2016-02-01

    Pupil size reflects autonomic response to different environmental and behavioral stimuli, and its dynamics have been linked to other autonomic correlates such as cardiac and respiratory rhythms. The aim of this study is to assess the nonlinear characteristics of pupil size of 25 normal subjects who participated in a psychophysiological experimental protocol with four experimental conditions, namely “baseline”, “anger”, “joy”, and “sadness”. Nonlinear measures, such as sample entropy, correlation dimension, and largest Lyapunov exponent, were computed on reconstructed signals of spontaneous fluctuations of pupil dilation. Nonparametric statistical tests were performed on surrogate data to verify that the nonlinear measures are an intrinsic characteristic of the signals. We then developed and applied a piecewise linear regression model to detrended fluctuation analysis (DFA). Two joinpoints and three scaling intervals were identified: slope α0, at slow time scales, represents a persistent nonstationary long-range correlation, whereas α1 and α2, at middle and fast time scales, respectively, represent long-range power-law correlations, similarly to DFA applied to heart rate variability signals. Of the computed complexity measures, α0 showed statistically significant differences among experimental conditions (p<0.001). Our results suggest that (a) pupil size at constant light condition is characterized by nonlinear dynamics, (b) three well-defined and distinct long-memory processes exist at different time scales, and (c) autonomic stimulation is partially reflected in nonlinear dynamics. PMID:26351899

  2. High performance screening, structural and molecular dynamics analysis to identify H1 inhibitors from TCM Database@Taiwan.

    PubMed

    Chang, Su-Sen; Huang, Hung-Jin; Chen, Calvin Yu-Chian

    2011-12-01

    New-type oseltamivir-resistant H1N1 influenza viruses have been a major threat to human health since the 2009 flu pandemic. To resolve the drug resistance issue, we aimed to identify a new type of inhibitors against H1 from traditional Chinese medicine (TCM) by employing the world's largest TCM database () for virtual screening and molecular dynamics (MD). From the virtual screening results, sodium (+)-isolaricireinol-2 alpha-sulfate, sodium 3,4-dihydroxy-5-methoxybenzoic acid methyl ester-4-sulfate, sodium (E)-7-hydroxy-1,7-bis(4-hydroxyphenyl)hept-5-ene-3S-sulfonate, and 3-methoxytyramine-betaxanthin were identified as potential drug-like compounds. MD simulation of the binding poses with the key residues Asp103 and Glu83, as well as other binding site residues, identified higher numbers of hydrogen bonds than N-Acetyl-D-Glucosamine (NAG), the natural ligand of the esterase domain in H1. Ionic bonds, salt bridges, and electrostatic energy also contribute to binding stability. Key binding residues include Lys71, Glu83, Asp103, and Arg238. Structural moieties promoting H-bond or salt bridge formations at these locations greatly contribute to a stable ligand-protein complex. An available sodium atom for ionic interactions with Asp103 can further stabilize the ligands. Based on virtual screening, MD simulation, and interaction energy evaluation, TCM candidates demonstrate good potential as novel H1 inhibitors. In addition, the identified stabilizing features can provide insights for designing highly stable H1 inhibitors. PMID:22012120

  3. Operational Dynamic Configuration Analysis

    NASA Technical Reports Server (NTRS)

    Lai, Chok Fung; Zelinski, Shannon

    2010-01-01

    Sectors may combine or split within areas of specialization in response to changing traffic patterns. This method of managing capacity and controller workload could be made more flexible by dynamically modifying sector boundaries. Much work has been done on methods for dynamically creating new sector boundaries [1-5]. Many assessments of dynamic configuration methods assume the current day baseline configuration remains fixed [6-7]. A challenging question is how to select a dynamic configuration baseline to assess potential benefits of proposed dynamic configuration concepts. Bloem used operational sector reconfigurations as a baseline [8]. The main difficulty is that operational reconfiguration data is noisy. Reconfigurations often occur frequently to accommodate staff training or breaks, or to complete a more complicated reconfiguration through a rapid sequence of simpler reconfigurations. Gupta quantified a few aspects of airspace boundary changes from this data [9]. Most of these metrics are unique to sector combining operations and not applicable to more flexible dynamic configuration concepts. To better understand what sort of reconfigurations are acceptable or beneficial, more configuration change metrics should be developed and their distribution in current practice should be computed. This paper proposes a method to select a simple sequence of configurations among operational configurations to serve as a dynamic configuration baseline for future dynamic configuration concept assessments. New configuration change metrics are applied to the operational data to establish current day thresholds for these metrics. These thresholds are then corroborated, refined, or dismissed based on airspace practitioner feedback. The dynamic configuration baseline selection method uses a k-means clustering algorithm to select the sequence of configurations and trigger times from a given day of operational sector combination data. The clustering algorithm selects a simplified

  4. Coupled dynamics analysis of wind energy systems

    NASA Technical Reports Server (NTRS)

    Hoffman, J. A.

    1977-01-01

    A qualitative description of all key elements of a complete wind energy system computer analysis code is presented. The analysis system addresses the coupled dynamics characteristics of wind energy systems, including the interactions of the rotor, tower, nacelle, power train, control system, and electrical network. The coupled dynamics are analyzed in both the frequency and time domain to provide the basic motions and loads data required for design, performance verification and operations analysis activities. Elements of the coupled analysis code were used to design and analyze candidate rotor articulation concepts. Fundamental results and conclusions derived from these studies are presented.

  5. Dynamic Event Tree Analysis Through RAVEN

    SciTech Connect

    A. Alfonsi; C. Rabiti; D. Mandelli; J. Cogliati; R. A. Kinoshita; A. Naviglio

    2013-09-01

    Conventional Event-Tree (ET) based methodologies are extensively used as tools to perform reliability and safety assessment of complex and critical engineering systems. One of the disadvantages of these methods is that timing/sequencing of events and system dynamics is not explicitly accounted for in the analysis. In order to overcome these limitations several techniques, also know as Dynamic Probabilistic Risk Assessment (D-PRA), have been developed. Monte-Carlo (MC) and Dynamic Event Tree (DET) are two of the most widely used D-PRA methodologies to perform safety assessment of Nuclear Power Plants (NPP). In the past two years, the Idaho National Laboratory (INL) has developed its own tool to perform Dynamic PRA: RAVEN (Reactor Analysis and Virtual control ENvironment). RAVEN has been designed in a high modular and pluggable way in order to enable easy integration of different programming languages (i.e., C++, Python) and coupling with other application including the ones based on the MOOSE framework, developed by INL as well. RAVEN performs two main tasks: 1) control logic driver for the new Thermo-Hydraulic code RELAP-7 and 2) post-processing tool. In the first task, RAVEN acts as a deterministic controller in which the set of control logic laws (user defined) monitors the RELAP-7 simulation and controls the activation of specific systems. Moreover, RAVEN also models stochastic events, such as components failures, and performs uncertainty quantification. Such stochastic modeling is employed by using both MC and DET algorithms. In the second task, RAVEN processes the large amount of data generated by RELAP-7 using data-mining based algorithms. This paper focuses on the first task and shows how it is possible to perform the analysis of dynamic stochastic systems using the newly developed RAVEN DET capability. As an example, the Dynamic PRA analysis, using Dynamic Event Tree, of a simplified pressurized water reactor for a Station Black-Out scenario is presented.

  6. Obtaining railpad properties via dynamic mechanical analysis

    NASA Astrophysics Data System (ADS)

    Oregui, M.; de Man, A.; Woldekidan, M. F.; Li, Z.; Dollevoet, R.

    2016-02-01

    In this paper, we propose combining dynamic mechanical analysis (DMA) and the time-temperature superposition principle to determine various railpad dynamic properties. Having accurate information regarding the dynamic properties of a railpad is a fundamental requirement for designing tracks and understanding track deterioration. By testing three different railpad types, we demonstrate that the dynamic behavior of railpads over a wide frequency range can be successfully obtained under different preloads and temperatures if time-temperature superposition can be applied. To investigate railpad aging, worn railpads taken from a mainline in the Netherlands are tested. In this case, worn railpads are softer and possess a lower damping capacity than new railpads. In addition to performing these measurements, a Prony series material model is proposed to reproduce the dynamic behavior of railpads. The Prony series model is in good agreement with the measurements. Measured railpad dynamic properties and the corresponding Prony series numerical model provide valuable information for track design and modeling.

  7. Dynamic and Performance Characteristics of Baseball Bats

    ERIC Educational Resources Information Center

    Bryant, Fred O.; And Others

    1977-01-01

    The dynamic and performance characteristics of wooden and aluminum baseball bats were investigated in two phases; the first dealing with the velocity of the batted balls, and the second with a study of centers of percussion and impulse response at the handle. (MJB)

  8. Dynamic analysis of process reactors

    SciTech Connect

    Shadle, L.J.; Lawson, L.O.; Noel, S.D.

    1995-06-01

    The approach and methodology of conducting a dynamic analysis is presented in this poster session in order to describe how this type of analysis can be used to evaluate the operation and control of process reactors. Dynamic analysis of the PyGas{trademark} gasification process is used to illustrate the utility of this approach. PyGas{trademark} is the gasifier being developed for the Gasification Product Improvement Facility (GPIF) by Jacobs-Siffine Engineering and Riley Stoker. In the first step of the analysis, process models are used to calculate the steady-state conditions and associated sensitivities for the process. For the PyGas{trademark} gasifier, the process models are non-linear mechanistic models of the jetting fluidized-bed pyrolyzer and the fixed-bed gasifier. These process sensitivities are key input, in the form of gain parameters or transfer functions, to the dynamic engineering models.

  9. Man/Machine Interaction Dynamics And Performance (MMIDAP) capability

    NASA Technical Reports Server (NTRS)

    Frisch, Harold P.

    1991-01-01

    The creation of an ability to study interaction dynamics between a machine and its human operator can be approached from a myriad of directions. The Man/Machine Interaction Dynamics and Performance (MMIDAP) project seeks to create an ability to study the consequences of machine design alternatives relative to the performance of both machine and operator. The class of machines to which this study is directed includes those that require the intelligent physical exertions of a human operator. While Goddard's Flight Telerobotic's program was expected to be a major user, basic engineering design and biomedical applications reach far beyond telerobotics. Ongoing efforts are outlined of the GSFC and its University and small business collaborators to integrate both human performance and musculoskeletal data bases with analysis capabilities necessary to enable the study of dynamic actions, reactions, and performance of coupled machine/operator systems.

  10. Dynamic classifiers improve pulverizer performance and more

    SciTech Connect

    Sommerlad, R.E.; Dugdale, K.L.

    2007-07-15

    Keeping coal-fired steam plants running efficiently and cleanly is a daily struggle. An article in the February 2007 issue of Power explained that one way to improve the combustion and emissions performance of a plant is to optimize the performance of its coal pulverizers. By adding a dynamic classifier to the pulverizers, you can better control coal particle sizing and fineness, and increase pulverizer capacity to boot. A dynamic classifier has an inner rotating cage and outer stationary vanes which, acting in concert, provide centrifugal or impinging classification. Replacing or upgrading a pulverizer's classifier from static to dynamic improves grinding performance reducing the level of unburned carbon in the coal in the process. The article describes the project at E.ON's Ratcliffe-on-Soar Power station in the UK to retrofit Loesche LSKS dynamic classifiers. It also mentions other successful projects at Scholven Power Station in Germany, Tilbury Power Station in the UK and J.B. Sims Power Plant in Michigan, USA. 8 figs.

  11. Toward a dynamical theory of body movement in musical performance

    PubMed Central

    Demos, Alexander P.; Chaffin, Roger; Kant, Vivek

    2014-01-01

    Musicians sway expressively as they play in ways that seem clearly related to the music, but quantifying the relationship has been difficult. We suggest that a complex systems framework and its accompanying tools for analyzing non-linear dynamical systems can help identify the motor synergies involved. Synergies are temporary assemblies of parts that come together to accomplish specific goals. We assume that the goal of the performer is to convey musical structure and expression to the audience and to other performers. We provide examples of how dynamical systems tools, such as recurrence quantification analysis (RQA), can be used to examine performers' movements and relate them to the musical structure and to the musician's expressive intentions. We show how detrended fluctuation analysis (DFA) can be used to identify synergies and discover how they are affected by the performer's expressive intentions. PMID:24904490

  12. DAS performance analysis

    SciTech Connect

    Bates, G.; Bodine, S.; Carroll, T.; Keller, M.

    1984-02-01

    This report begins with an overview of the Data Acquisition System (DAS), which supports several of PPPL's experimental devices. Performance measurements which were taken on DAS and the tools used to make them are then described.

  13. Dynamic Analysis of Nuclear Energy System Strategies

    SciTech Connect

    Den Durpel, Luc Van

    2004-06-17

    DANESS is an integrated process model for nuclear energy systems allowing the simulation of multiple reactors and fuel cycles in a continuously changing nuclear reactor park configuration. The model is energy demand driven and simulates all nuclear fuel cycle facilites, up to 10 reactors and fuels. Reactor and fuel cycle facility history are traced and the cost of generating energy is calculated per reactor and for total nuclear energy system. The DANESS model aims at performing dynamic systems analysis of nuclear energy development used for integrated analysis of development paths for nuclear energy, parameter scoping for new nuclear energy systems, economic analysis of nuclear energy, government role analysis, and education.

  14. Integrating performance data collection, analysis, and visualization

    NASA Technical Reports Server (NTRS)

    Malony, Allen D.; Reed, Daniel A.; Rudolph, David C.

    1990-01-01

    An integrated data collection, analysis, and data visualization environment is described for a specific parallel system - the Intel iPSC/2 hypercube. The data collection components of the environment encompass software event tracing at the operating system with a program level and a hardware-based performance monitoring system used to capture software events. A visualization system based on the X-window environment permits dynamic display and reduction of performance data. A performance data collection, analysis, and visualization environment makes it possible to access the effects of architectural and system software variations.

  15. Dynamic analysis of very flexible beams

    NASA Astrophysics Data System (ADS)

    Fotouhi, R.

    2007-08-01

    The dynamic analysis of flexible beams with large deformations is difficult and few studies have been performed. In this paper, the vibration analysis of several very flexible beams with large deflections using the finite element approach is studied. The examples were a cantilever beam and rotating flexible robot arms. The results were compared with the results available in the published literature. Several successful checks on the finite element results were performed to ensure the accuracy of the solutions. Due to the geometrical nonlinearity, several static equilibrium shapes can exist for large deflections of a cantilever beam for a given load. Nonlinear dynamic finite element analysis was implemented to investigate the stability of these shapes.

  16. Dependability and performability analysis

    NASA Technical Reports Server (NTRS)

    Trivedi, Kishor S.; Ciardo, Gianfranco; Malhotra, Manish; Sahner, Robin A.

    1993-01-01

    Several practical issues regarding specifications and solution of dependability and performability models are discussed. Model types with and without rewards are compared. Continuous-time Markov chains (CTMC's) are compared with (continuous-time) Markov reward models (MRM's) and generalized stochastic Petri nets (GSPN's) are compared with stochastic reward nets (SRN's). It is shown that reward-based models could lead to more concise model specifications and solution of a variety of new measures. With respect to the solution of dependability and performability models, three practical issues were identified: largeness, stiffness, and non-exponentiality, and a variety of approaches are discussed to deal with them, including some of the latest research efforts.

  17. Analysis of EDP performance

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The objective of this contract was the investigation of the potential performance gains that would result from an upgrade of the Space Station Freedom (SSF) Data Management System (DMS) Embedded Data Processor (EDP) '386' design with the Intel Pentium (registered trade-mark of Intel Corp.) '586' microprocessor. The Pentium ('586') is the latest member of the industry standard Intel X86 family of CISC (Complex Instruction Set Computer) microprocessors. This contract was scheduled to run in parallel with an internal IBM Federal Systems Company (FSC) Internal Research and Development (IR&D) task that had the goal to generate a baseline flight design for an upgraded EDP using the Pentium. This final report summarizes the activities performed in support of Contract NAS2-13758. Our plan was to baseline performance analyses and measurements on the latest state-of-the-art commercially available Pentium processor, representative of the proposed space station design, and then phase to an IBM capital funded breadboard version of the flight design (if available from IR&D and Space Station work) for additional evaluation of results. Unfortunately, the phase-over to the flight design breadboard did not take place, since the IBM Data Management System (DMS) for the Space Station Freedom was terminated by NASA before the referenced capital funded EDP breadboard could be completed. The baseline performance analyses and measurements, however, were successfully completed, as planned, on the commercial Pentium hardware. The results of those analyses, evaluations, and measurements are presented in this final report.

  18. Probabilistic assessment of dynamic system performance. Part 3

    SciTech Connect

    Belhadj, M.

    1993-12-31

    Accurate prediction of dynamic system failure behavior can be important for the reliability and risk analyses of nuclear power plants, as well as for their backfitting to satisfy given constraints on overall system reliability, or optimization of system performance. Global analysis of dynamic systems through investigating the variations in the structure of the attractors of the system and the domains of attraction of these attractors as a function of the system parameters is also important for nuclear technology in order to understand the fault-tolerance as well as the safety margins of the system under consideration and to insure a safe operation of nuclear reactors. Such a global analysis would be particularly relevant to future reactors with inherent or passive safety features that are expected to rely on natural phenomena rather than active components to achieve and maintain safe shutdown. Conventionally, failure and global analysis of dynamic systems necessitate the utilization of different methodologies which have computational limitations on the system size that can be handled. Using a Chapman-Kolmogorov interpretation of system dynamics, a theoretical basis is developed that unifies these methodologies as special cases and which can be used for a comprehensive safety and reliability analysis of dynamic systems.

  19. Dynamical analysis of generalized Galileon cosmology

    SciTech Connect

    Leon, Genly; Saridakis, Emmanuel N. E-mail: Emmanuel_Saridakis@baylor.edu

    2013-03-01

    We perform a detailed dynamical analysis of generalized Galileon cosmology, incorporating also the requirements of ghost and instabilities absence. We find that there are not any new stable late-time solutions apart from those of standard quintessence. Furthermore, depending on the model parameters the Galileons may survive at late times or they may completely disappear by the dynamics, however the corresponding observables are always independent of the Galileon terms, determined only by the usual action terms. Thus, although the Galileons can play an important role at inflationary or at recent times, in the future, when the universe will asymptotically reach its stable state, they will not have any effect on its evolution.

  20. MPQC: Performance Analysis and Optimization

    SciTech Connect

    Sarje, Abhinav; Williams, Samuel; Bailey, David

    2012-11-30

    MPQC (Massively Parallel Quantum Chemistry) is a widely used computational quantum chemistry code. It is capable of performing a number of computations commonly occurring in quantum chemistry. In order to achieve better performance of MPQC, in this report we present a detailed performance analysis of this code. We then perform loop and memory access optimizations, and measure performance improvements by comparing the performance of the optimized code with that of the original MPQC code. We observe that the optimized MPQC code achieves a significant improvement in the performance through a better utilization of vector processing and memory hierarchies.

  1. Software Performs Complex Design Analysis

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Designers use computational fluid dynamics (CFD) to gain greater understanding of the fluid flow phenomena involved in components being designed. They also use finite element analysis (FEA) as a tool to help gain greater understanding of the structural response of components to loads, stresses and strains, and the prediction of failure modes. Automated CFD and FEA engineering design has centered on shape optimization, which has been hindered by two major problems: 1) inadequate shape parameterization algorithms, and 2) inadequate algorithms for CFD and FEA grid modification. Working with software engineers at Stennis Space Center, a NASA commercial partner, Optimal Solutions Software LLC, was able to utilize its revolutionary, one-of-a-kind arbitrary shape deformation (ASD) capability-a major advancement in solving these two aforementioned problems-to optimize the shapes of complex pipe components that transport highly sensitive fluids. The ASD technology solves the problem of inadequate shape parameterization algorithms by allowing the CFD designers to freely create their own shape parameters, therefore eliminating the restriction of only being able to use the computer-aided design (CAD) parameters. The problem of inadequate algorithms for CFD grid modification is solved by the fact that the new software performs a smooth volumetric deformation. This eliminates the extremely costly process of having to remesh the grid for every shape change desired. The program can perform a design change in a markedly reduced amount of time, a process that would traditionally involve the designer returning to the CAD model to reshape and then remesh the shapes, something that has been known to take hours, days-even weeks or months-depending upon the size of the model.

  2. Scaled control moment gyroscope dynamics effects on performance

    NASA Astrophysics Data System (ADS)

    Leve, Frederick A.

    2015-05-01

    The majority of the literature that discusses the dynamics of control moment gyroscopes (CMG) contains formulations that are not derived from first principles and make simplifying assumptions early in the derivation, possibly neglecting important contributions. For small satellites, additional dynamics that are no longer negligible are shown to cause an increase in torque error and loss of torque amplification. The goal of the analysis presented here is to provide the reader with a complete and general analytical derivation of the equations for dynamics of a spacecraft with n-CMG and to discuss the performance degradation imposed to CMG actuators when scaling them for small satellites. The paper first derives the equations of motion from first principles for a very general case of a spacecraft with n-CMG. Each contribution of the dynamics is described with its effect on the performance of CMG and its significance on scaled CMG performance is addressed. It is shown analytically and verified numerically, that CMG do not scale properly with performance and care must be taken in their design to trade performance, size, mass, and power when reducing their scale.

  3. Prediction of Muscle Performance During Dynamic Repetitive Exercise

    NASA Technical Reports Server (NTRS)

    Byerly, D. L.; Byerly, K. A.; Sognier, M. A.; Squires, W. G.

    2002-01-01

    A method for predicting human muscle performance was developed. Eight test subjects performed a repetitive dynamic exercise to failure using a Lordex spinal machine. Electromyography (EMG) data was collected from the erector spinae. Evaluation of the EMG data using a 5th order Autoregressive (AR) model and statistical regression analysis revealed that an AR parameter, the mean average magnitude of AR poles, can predict performance to failure as early as the second repetition of the exercise. Potential applications to the space program include evaluating on-orbit countermeasure effectiveness, maximizing post-flight recovery, and future real-time monitoring capability during Extravehicular Activity.

  4. Lidar performance analysis

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.

    1994-01-01

    Section 1 details the theory used to build the lidar model, provides results of using the model to evaluate AEOLUS design instrument designs, and provides snapshots of the visual appearance of the coded model. Appendix A contains a Fortran program to calculate various forms of the refractive index structure function. This program was used to determine the refractive index structure function used in the main lidar simulation code. Appendix B contains a memo on the optimization of the lidar telescope geometry for a line-scan geometry. Appendix C contains the code for the main lidar simulation and brief instruction on running the code. Appendix D contains a Fortran code to calculate the maximum permissible exposure for the eye from the ANSI Z136.1-1992 eye safety standards. Appendix E contains a paper on the eye safety analysis of a space-based coherent lidar presented at the 7th Coherent Laser Radar Applications and Technology Conference, Paris, France, 19-23 July 1993.

  5. Metaconcrete: designed aggregates to enhance dynamic performance

    NASA Astrophysics Data System (ADS)

    Mitchell, Stephanie J.; Pandolfi, Anna; Ortiz, Michael

    2014-04-01

    We propose a new type of concrete for the attenuation of elastic waves induced by dynamic excitation. In this metamaterial, which we call metaconcrete, the stone, sand, and gravel aggregates of standard concrete are replaced with spherical inclusions consisting of a heavy metal core coated with a soft outer layer. These engineered aggregates can be tuned so that particular frequencies of a propagating blast wave will activate resonant oscillations of the heavy mass within the inclusions. The resonant behavior causes the system to exhibit negative effective mass, and this interaction between the wave motion and the resonant aggregates results in the attenuation of the applied dynamic loading. We introduce the concept of negative mass by deriving the effective momentum mass for the system and we define the geometrical and material parameters for the design of resonant aggregates. We develop finite element models for the analysis of metaconcrete behavior, defining a section of slab containing a periodic arrangement of inclusions. By computing the energy histories for the system when subject to a blast load, we show that there is a transfer of energy between the inclusions and the surrounding mortar. The inclusions are able to absorb a significant portion of the applied energy, resulting in a reduction in the amount of stress carried by the mortar phase and greatly improving the ability of the material to resist damage under explosive dynamic loading.

  6. Complex dynamics of text analysis

    NASA Astrophysics Data System (ADS)

    Ke, Xiaohua; Zeng, Yongqiang; Ma, Qinghua; Zhu, Lin

    2014-12-01

    This paper presents a novel method for the analysis of nonlinear text quality in Chinese language. Texts produced by university students in China were represented as scale-free networks (word adjacency model), from which typical network features such as the in/outdegree, clustering coefficient and network dynamics were obtained. The method integrates the classical concepts of network feature representation and text quality series variation. The analytical and numerical scheme leads to a parameter space representation that constitutes a valid alternative to represent the network features. The results reveal that complex network features of different text qualities can be clearly revealed and applied to potential applications in other instances of text analysis.

  7. Symmetry-enhanced performance of dynamical decoupling

    SciTech Connect

    Pasini, S.; Uhrig, G. S.

    2011-10-15

    We consider a system with general decoherence and a quadratic dynamical decoupling sequence (QDD) for the coherence control of a qubit coupled to a bath of spins. We investigate the influence of the geometry and of the initial conditions of the bath on the performance of the sequence. The overall performance is quantified by a distance norm d. It is expected that d scales with {tau}, the total duration of the sequence, as {tau}{sup min{l_brace}N{sub x},N{sub z}{r_brace}+1}, where N{sub x} and N{sub z} are the number of pulses of the outer and of the inner sequence, respectively. We show both numerically and analytically that the state of the bath can boost the performance of QDD under certain conditions: The scaling of QDD for a given number of pulses can be enhanced by a factor of 2 if the bath is prepared in a highly symmetric state and if the system Hamiltonian is SU(2) invariant.

  8. Reproducibility of Dynamic Contrast-Enhanced MRI in Renal Cell Carcinoma: A Prospective Analysis on Intra- and Interobserver and Scan-Rescan Performance of Pharmacokinetic Parameters.

    PubMed

    Wang, Haiyi; Su, Zihua; Ye, Huiyi; Xu, Xiao; Sun, Zhipeng; Li, Lu; Duan, Feixue; Song, Yuanyuan; Lambrou, Tryphon; Ma, Lin

    2015-09-01

    The objective of this study was to investigate the intra- and interobserver as well as scan-rescan reproducibility of quantitative parameters of renal cell carcinomas (RCCs) with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). A total of 21 patients with clear cell RCCs (17 men, 4 woman; age 37-69 years, mean age 54.6 years, mean size, 5.0 ± 2.2 cm) were prospectively recruited from September 2012 to November 2012. Patients underwent paired DCE-MRI studies on a 3.0 T MR system with an interval of 48 to 72 hours. The extended-Tofts model and population-based arterial input function were used to calculate kinetic parameters. Three observers defined the 2-dimensional whole-tumor region of interest at the slice with the maximum diameter of the RCC. Intraobserver and scan-rescan differences were assessed using paired t tests, whereas interobserver differences using two-way analysis of variance. Intra- and interobserver reproducibility and scan-rescan reproducibility were evaluated using within-subject coefficient of variation (wCoV) and intraclass correlation coefficient (ICC). There were no significant intra-, interobserver, or scan-rescan differences in parameters (all P > 0.05). All ICCs for intra- and interobserver agreements were >0.75 (P < 0.05), whereas the scan-rescan agreement was moderate to good; V(e) (0.764, 95% confidence interval [CI]: 0.378-0.925) and K(ep) (0.906, 95% CI: 0.710-0.972) had higher ICC than K(trans) (0.686; 95% CI: 0.212-0.898) and V(p) (0.657; 95% CI: 0.164-0.888). In intra- and interobserver variability analyses, all parameters except V(p) had low wCoV values. K(trans) and V(e) had slightly lower intraobserver wCoV (1.2% and 0.9%) compared with K(ep) (3.7%), whereas all 3 of these parameters had similar interobserver wCoV values (2.5%, 3.1%, and 2.9%, respectively). Regarding scan-rescan variability, K(trans) and K(ep) showed slightly higher variation (15.6% and 15.4%) than V(e) (10.1%). V(p) had the largest

  9. Performance of a dynamic atmosphere generation system

    SciTech Connect

    Nano, G.; Borroni, A.; Mazza, B.

    1987-09-01

    A controlled test atmosphere system for gaseous pollutants was designed and constructed. For a reliable characterization of indoor air pollution, a suitable set of sampling and analysis procedures has to be devised and accomplished. The precision and accuracy of the measurements must be determined exactly for a correct interpretation of the results. The two main difficulties appear to be the actual generation of the individual standard and the preparations of physico-chemically thoroughly characterized mixtures. This system utilized two methods for generation of dynamic standards: permeation tubes and gas saturators. Special care also was devoted to the achievement of both a good time stability of the concentration of the standard mixtures and a satisfactory agreement between expected and measured concentration values.

  10. Computational fluid dynamics studies of nuclear rocket performance

    NASA Technical Reports Server (NTRS)

    Stubbs, Robert M.; Benson, Thomas J.; Kim, Suk C.

    1991-01-01

    A CFD analysis of a low pressure nuclear rocket concept is presented with the use of an advanced chemical kinetics, Navier-Stokes code. The computations describe the flow field in detail,including gas dynamic, thermodynamic and chemical properties, as well as global performance quantities such as specific impulse. Computational studies of several rocket nozzle shapes are conducted in an attempt to maximize hydrogen recombination. These Navier-Stokes calculations, which include real gas and viscous effects, predict lower performance values than have been reported heretofore.

  11. Computational fluid dynamics studies of nuclear rocket performance

    NASA Technical Reports Server (NTRS)

    Stubbs, Robert M.; Kim, Suk C.; Benson, Thomas J.

    1994-01-01

    A CFD analysis of a low pressure nuclear rocket concept is presented with the use of an advanced chemical kinetics, Navier-Stokes code. The computations describe the flow field in detail, including gas dynamic, thermodynamic and chemical properties, as well as global performance quantities such as specific impulse. Computational studies of several rocket nozzle shapes are conducted in an attempt to maximize hydrogen recombination. These Navier-Stokes calculations, which include real gas and viscous effects, predict lower performance values than have been reported heretofore.

  12. Epock: rapid analysis of protein pocket dynamics

    PubMed Central

    Laurent, Benoist; Chavent, Matthieu; Cragnolini, Tristan; Dahl, Anna Caroline E.; Pasquali, Samuela; Derreumaux, Philippe; Sansom, Mark S.P.; Baaden, Marc

    2015-01-01

    Summary: The volume of an internal protein pocket is fundamental to ligand accessibility. Few programs that compute such volumes manage dynamic data from molecular dynamics (MD) simulations. Limited performance often prohibits analysis of large datasets. We present Epock, an efficient command-line tool that calculates pocket volumes from MD trajectories. A plugin for the VMD program provides a graphical user interface to facilitate input creation, run Epock and analyse the results. Availability and implementation: Epock C++ source code, Python analysis scripts, VMD Tcl plugin, documentation and installation instructions are freely available at http://epock.bitbucket.org. Contact: benoist.laurent@gmail.com or baaden@smplinux.de Supplementary information: Supplementary data are available at Bioinformatics online. PMID:25505095

  13. Prediction of muscle performance during dynamic repetitive movement

    NASA Technical Reports Server (NTRS)

    Byerly, D. L.; Byerly, K. A.; Sognier, M. A.; Squires, W. G.

    2003-01-01

    BACKGROUND: During long-duration spaceflight, astronauts experience progressive muscle atrophy and often perform strenuous extravehicular activities. Post-flight, there is a lengthy recovery period with an increased risk for injury. Currently, there is a critical need for an enabling tool to optimize muscle performance and to minimize the risk of injury to astronauts while on-orbit and during post-flight recovery. Consequently, these studies were performed to develop a method to address this need. METHODS: Eight test subjects performed a repetitive dynamic exercise to failure at 65% of their upper torso weight using a Lordex spinal machine. Surface electromyography (SEMG) data was collected from the erector spinae back muscle. The SEMG data was evaluated using a 5th order autoregressive (AR) model and linear regression analysis. RESULTS: The best predictor found was an AR parameter, the mean average magnitude of AR poles, with r = 0.75 and p = 0.03. This parameter can predict performance to failure as early as the second repetition of the exercise. CONCLUSION: A method for predicting human muscle performance early during dynamic repetitive exercise was developed. The capability to predict performance to failure has many potential applications to the space program including evaluating countermeasure effectiveness on-orbit, optimizing post-flight recovery, and potential future real-time monitoring capability during extravehicular activity.

  14. Analysis of driver performance under reduced visibility

    NASA Technical Reports Server (NTRS)

    Kaeppler, W. D.

    1982-01-01

    Mathematical models describing vehicle dynamics as well as human behavior may be useful in evaluating driver performance and in establishing design criteria for vehicles more compatible with man. In 1977, a two level model of driver steering behavior was developed, but its parameters were identified for clear visibility conditions only. Since driver performance degrades under conditions of reduced visibility, e.g., fog, the two level model should be investigated to determine its applicability to such conditions. The data analysis of a recently performed driving simulation experiment showed that the model still performed reasonably well under fog conditions, although there was a degradation in its predictive capacity during fog. Some additional parameters affecting anticipation and lag time may improve the model's performance for reduced visibility conditions.

  15. Dynamic Analysis of Nuclear Energy System Strategies

    Energy Science and Technology Software Center (ESTSC)

    2004-06-17

    DANESS is an integrated process model for nuclear energy systems allowing the simulation of multiple reactors and fuel cycles in a continuously changing nuclear reactor park configuration. The model is energy demand driven and simulates all nuclear fuel cycle facilites, up to 10 reactors and fuels. Reactor and fuel cycle facility history are traced and the cost of generating energy is calculated per reactor and for total nuclear energy system. The DANESS model aims atmore » performing dynamic systems analysis of nuclear energy development used for integrated analysis of development paths for nuclear energy, parameter scoping for new nuclear energy systems, economic analysis of nuclear energy, government role analysis, and education.« less

  16. Dynamic Web Pages: Performance Impact on Web Servers.

    ERIC Educational Resources Information Center

    Kothari, Bhupesh; Claypool, Mark

    2001-01-01

    Discussion of Web servers and requests for dynamic pages focuses on experimentally measuring and analyzing the performance of the three dynamic Web page generation technologies: CGI, FastCGI, and Servlets. Develops a multivariate linear regression model and predicts Web server performance under some typical dynamic requests. (Author/LRW)

  17. Simplified Dynamic Analysis of Grinders Spindle Node

    NASA Astrophysics Data System (ADS)

    Demec, Peter

    2014-12-01

    The contribution deals with the simplified dynamic analysis of surface grinding machine spindle node. Dynamic analysis is based on the use of the transfer matrix method, which is essentially a matrix form of method of initial parameters. The advantage of the described method, despite the seemingly complex mathematical apparatus, is primarily, that it does not require for solve the problem of costly commercial software using finite element method. All calculations can be made for example in MS Excel, which is advantageous especially in the initial stages of constructing of spindle node for the rapid assessment of the suitability its design. After detailing the entire structure of spindle node is then also necessary to perform the refined dynamic analysis in the environment of FEM, which it requires the necessary skills and experience and it is therefore economically difficult. This work was developed within grant project KEGA No. 023TUKE-4/2012 Creation of a comprehensive educational - teaching material for the article Production technique using a combination of traditional and modern information technology and e-learning.

  18. STEP Tether Dynamics Preliminary Analysis

    NASA Technical Reports Server (NTRS)

    Glaese, John R.

    2000-01-01

    The General Tethered Object Simulation System (GTOSS) has been successfully converted to the PC environment. GTOSS has been run under Microsoft Windows 95, 98 and NT4.0 with no problems noted. Adaptation to the PC environment and definition of the 3 three body configuration required resizing some of the GTOSS internal data arrays. To allow studies of the tether dynamics accompanying electrodynamic thrust, a tether current flow model has also been developed for GTOSS. This model includes effects due to the earth's magnetic field and ionosphere, tether conductivity, temperature, motion, shape and available power. Sample cases have been defined for a proposed STEP-AIRSEDS (Space Transfer using Electrodynamic Propulsion-The Michigan Technic Corporation proposed tether missions for commercial applications) three body configuration. This required definition of a 6th power scenario for GTOSS. This power scenario allows a user to specify whether orbit raising or orbit lowering is to be performed by selecting the number of the tether. Orbit raising and orbit lowering sample cases have been run successfully. Results from these runs have been included in this report. Results have only been generated so far for a three body configuration. Only point end masses have been represented. No attitude dynamics have been included. Initial results suggest that tether current can have significant and detrimental effects on tether dynamics and provisions will have to be made for control of it. This control will have to be considered in connection with desired target orbits for electrodynamic thrusting, as well as end body attitude control, momentum management of proposed control moment gyros, solar array pointing. All of these items will interact and thus, any system simulation will have to have each of these effects modeled in sufficient detail to display these interactions.

  19. Evaluating the influence of physical, economic and managerial factors on sheet erosion in rangelands of SW Spain by performing a sensitivity analysis on an integrated dynamic model.

    PubMed

    Ibáñez, J; Lavado Contador, J F; Schnabel, S; Martínez Valderrama, J

    2016-02-15

    An integrated dynamic model was used to evaluate the influence of climatic, soil, pastoral, economic and managerial factors on sheet erosion in rangelands of SW Spain (dehesas). This was achieved by means of a variance-based sensitivity analysis. Topsoil erodibility, climate change and a combined factor related to soil water storage capacity and the pasture production function were the factors which influenced water erosion the most. Of them, climate change is the main source of uncertainty, though in this study it caused a reduction in the mean and the variance of long-term erosion rates. The economic and managerial factors showed scant influence on soil erosion, meaning that it is unlikely to find such influence in the study area for the time being. This is because the low profitability of the livestock business maintains stocking rates at low levels. However, the potential impact of livestock, through which economic and managerial factors affect soil erosion, proved to be greater in absolute value than the impact of climate change. Therefore, if changes in some economic or managerial factors led to higher stocking rates in the future, significant increases in erosion rates would be expected. PMID:26657389

  20. Dynamical analysis of highly excited molecular spectra

    SciTech Connect

    Kellman, M.E.

    1993-12-01

    The goal of this program is new methods for analysis of spectra and dynamics of highly excited vibrational states of molecules. In these systems, strong mode coupling and anharmonicity give rise to complicated classical dynamics, and make the simple normal modes analysis unsatisfactory. New methods of spectral analysis, pattern recognition, and assignment are sought using techniques of nonlinear dynamics including bifurcation theory, phase space classification, and quantization of phase space structures. The emphasis is chaotic systems and systems with many degrees of freedom.

  1. Dynamic Spatial Performance and General Intelligence.

    ERIC Educational Resources Information Center

    Jackson, Douglas N., III; And Others

    1993-01-01

    In a computerized video-game-like spatial ability measure administered to 94 university students, the number of target hits was correlated with verbal intelligence quotient. The dynamic spatial measure does not load substantially on a general intellectual ability factor, but it does provide additional evidence that dynamic spatial ability is…

  2. Techniques for Automated Performance Analysis

    SciTech Connect

    Marcus, Ryan C.

    2014-09-02

    The performance of a particular HPC code depends on a multitude of variables, including compiler selection, optimization flags, OpenMP pool size, file system load, memory usage, MPI configuration, etc. As a result of this complexity, current predictive models have limited applicability, especially at scale. We present a formulation of scientific codes, nodes, and clusters that reduces complex performance analysis to well-known mathematical techniques. Building accurate predictive models and enhancing our understanding of scientific codes at scale is an important step towards exascale computing.

  3. Inlet Performance Analysis Code Developed

    NASA Technical Reports Server (NTRS)

    Jules, Kenol; Barnhart, Paul J.

    1998-01-01

    The design characteristics of an inlet very much depend on whether the inlet is to be flown at subsonic, supersonic, or hypersonic speed. Whichever the case, the primary function of an inlet is to deliver free-stream air to the engine face at the highest stagnation pressure possible and with the lowest possible variation in both stagnation pressure and temperature. At high speeds, this is achieved by a system of oblique and/or normal shock waves, and possibly some isentropic compression. For both subsonic and supersonic flight, current design practice indicates that the inlet should deliver the air to the engine face at approximately Mach 0.45. As a result, even for flight in the high subsonic regime, the inlet must retard (or diffuse) the air substantially. Second, the design of an inlet is influenced largely by the compromise between high performance and low weight. This compromise involves tradeoffs between the mission requirements, flight trajectory, airframe aerodynamics, engine performance, and weight-all of which, in turn, influence each other. Therefore, to study the effects of some of these influential factors, the Propulsion System Analysis Office of the NASA Lewis Research Center developed the Inlet Performance Analysis Code (IPAC). This code uses oblique shock and Prandtl-Meyer expansion theory to predict inlet performance. It can be used to predict performance for a given inlet geometric design such as pitot, axisymmetric, and two-dimensional. IPAC also can be used to design preliminary inlet systems and to make subsequent performance analyses. It computes the total pressure, the recovery, the airflow, and the drag coefficients. The pressure recovery includes losses associated with normal and oblique shocks, internal and external friction, the sharp lip, and diffuser components. Flow rate includes captured, engine, spillage, bleed, and bypass flows. The aerodynamic drag calculation includes drags associated with spillage, cowl lip suction, wave, bleed

  4. Dynamic analysis of the Milad Tower

    NASA Astrophysics Data System (ADS)

    Wilhelm, Edwin; Ford, Mitchell; Coelho, Darren; Lawler, Lachlan; Ansourian, Peter; Alonso-Marroquin, Fernando; Tahmasebinia, Faham

    2016-08-01

    This report involves the modelling of the Milad Tower using the finite element analysis program Strand7. A dynamic analysis was performed on the structure in order to understand the deflections and stresses as a result of earthquake and wind loading. In particular, Linear Static as well as Natural Frequency and Spectral Response solvers were used to determine the behaviour of the structure under loading. The findings of the report highlight that the structure was modelled accurately with the outputs representing realistic values. The report suggests that the design of the beams, columns, slabs and all structural members was sufficient enough to support the tower during maximum loading cases. The governing load case was earthquake loading.

  5. DynaMod: dynamic functional modularity analysis

    PubMed Central

    Sun, Choong-Hyun; Hwang, Taeho; Oh, Kimin; Yi, Gwan-Su

    2010-01-01

    A comprehensive analysis of enriched functional categories in differentially expressed genes is important to extract the underlying biological processes of genome-wide expression profiles. Moreover, identification of the network of significant functional modules in these dynamic processes is an interesting challenge. This study introduces DynaMod, a web-based application that identifies significant functional modules reflecting the change of modularity and differential expressions that are correlated with gene expression profiles under different conditions. DynaMod allows the inspection of a wide variety of functional modules such as the biological pathways, transcriptional factor–target gene groups, microRNA–target gene groups, protein complexes and hub networks involved in protein interactome. The statistical significance of dynamic functional modularity is scored based on Z-statistics from the average of mutual information (MI) changes of involved gene pairs under different conditions. Significantly correlated gene pairs among the functional modules are used to generate a correlated network of functional categories. In addition to these main goals, this scoring strategy supports better performance to detect significant genes in microarray analyses, as the scores of correlated genes show the superior characteristics of the significance analysis compared with those of individual genes. DynaMod also offers cross-comparison between different analysis outputs. DynaMod is freely accessible at http://piech.kaist.ac.kr/dynamod. PMID:20460468

  6. Fusion metrics for dynamic situation analysis

    NASA Astrophysics Data System (ADS)

    Blasch, Erik P.; Pribilski, Mike; Daughtery, Bryan; Roscoe, Brian; Gunsett, Josh

    2004-08-01

    To design information fusion systems, it is important to develop metrics as part of a test and evaluation strategy. In many cases, fusion systems are designed to (1) meet a specific set of user information needs (IN), (2) continuously validate information pedigree and updates, and (3) maintain this performance under changing conditions. A fusion system"s performance is evaluated in many ways. However, developing a consistent set of metrics is important for standardization. For example, many track and identification metrics have been proposed for fusion analysis. To evaluate a complete fusion system performance, level 4 sensor management and level 5 user refinement metrics need to be developed simultaneously to determine whether or not the fusion system is meeting information needs. To describe fusion performance, the fusion community needs to agree on a minimum set of metrics for user assessment and algorithm comparison. We suggest that such a minimum set should include feasible metrics of accuracy, confidence, throughput, timeliness, and cost. These metrics can be computed as confidence (probability), accuracy (error), timeliness (delay), throughput (amount) and cost (dollars). In this paper, we explore an aggregate set of metrics for fusion evaluation and demonstrate with information need metrics for dynamic situation analysis.

  7. Dynamic Hurricane Data Analysis Tool

    NASA Technical Reports Server (NTRS)

    Knosp, Brian W.; Li, Peggy; Vu, Quoc A.

    2009-01-01

    A dynamic hurricane data analysis tool allows users of the JPL Tropical Cyclone Information System (TCIS) to analyze data over a Web medium. The TCIS software is described in the previous article, Tropical Cyclone Information System (TCIS) (NPO-45748). This tool interfaces with the TCIS database to pull in data from several different atmospheric and oceanic data sets, both observed by instruments. Users can use this information to generate histograms, maps, and profile plots for specific storms. The tool also displays statistical values for the user-selected parameter for the mean, standard deviation, median, minimum, and maximum values. There is little wait time, allowing for fast data plots over date and spatial ranges. Users may also zoom-in for a closer look at a particular spatial range. This is version 1 of the software. Researchers will use the data and tools on the TCIS to understand hurricane processes, improve hurricane forecast models and identify what types of measurements the next generation of instruments will need to collect.

  8. Systems-Dynamic Analysis for Neighborhood Study

    EPA Science Inventory

    Systems-dynamic analysis (or system dynamics (SD)) helps planners identify interrelated impacts of transportation and land-use policies on neighborhood-scale economic outcomes for households and businesses, among other applications. This form of analysis can show benefits and tr...

  9. Rumination and Performance in Dynamic, Team Sport.

    PubMed

    Roy, Michael M; Memmert, Daniel; Frees, Anastasia; Radzevick, Joseph; Pretz, Jean; Noël, Benjamin

    2015-01-01

    People high in rumination are good at tasks that require persistence whereas people low in rumination is good at tasks that require flexibility. Here we examine real world implications of these differences in dynamic, team sport. In two studies, we found that professional male football (soccer) players from Germany and female field hockey players on the US national team were lower in rumination than were non-athletes. Further, low levels of rumination were associated with a longer career at a higher level in football players. Results indicate that athletes in dynamic, team sport might benefit from the flexibility associated with being low in rumination. PMID:26779110

  10. Rumination and Performance in Dynamic, Team Sport

    PubMed Central

    Roy, Michael M.; Memmert, Daniel; Frees, Anastasia; Radzevick, Joseph; Pretz, Jean; Noël, Benjamin

    2016-01-01

    People high in rumination are good at tasks that require persistence whereas people low in rumination is good at tasks that require flexibility. Here we examine real world implications of these differences in dynamic, team sport. In two studies, we found that professional male football (soccer) players from Germany and female field hockey players on the US national team were lower in rumination than were non-athletes. Further, low levels of rumination were associated with a longer career at a higher level in football players. Results indicate that athletes in dynamic, team sport might benefit from the flexibility associated with being low in rumination. PMID:26779110

  11. Dynamic Open Inquiry Performances of High-School Biology Students

    ERIC Educational Resources Information Center

    Zion, Michal; Sadeh, Irit

    2010-01-01

    In examining open inquiry projects among high-school biology students, we found dynamic inquiry performances expressed in two criteria: "changes occurring during inquiry" and "procedural understanding". Characterizing performances in a dynamic open inquiry project can shed light on both the procedural and epistemological scientific understanding…

  12. Scalable Performance Measurement and Analysis

    SciTech Connect

    Gamblin, Todd

    2009-01-01

    Concurrency levels in large-scale, distributed-memory supercomputers are rising exponentially. Modern machines may contain 100,000 or more microprocessor cores, and the largest of these, IBM's Blue Gene/L, contains over 200,000 cores. Future systems are expected to support millions of concurrent tasks. In this dissertation, we focus on efficient techniques for measuring and analyzing the performance of applications running on very large parallel machines. Tuning the performance of large-scale applications can be a subtle and time-consuming task because application developers must measure and interpret data from many independent processes. While the volume of the raw data scales linearly with the number of tasks in the running system, the number of tasks is growing exponentially, and data for even small systems quickly becomes unmanageable. Transporting performance data from so many processes over a network can perturb application performance and make measurements inaccurate, and storing such data would require a prohibitive amount of space. Moreover, even if it were stored, analyzing the data would be extremely time-consuming. In this dissertation, we present novel methods for reducing performance data volume. The first draws on multi-scale wavelet techniques from signal processing to compress systemwide, time-varying load-balance data. The second uses statistical sampling to select a small subset of running processes to generate low-volume traces. A third approach combines sampling and wavelet compression to stratify performance data adaptively at run-time and to reduce further the cost of sampled tracing. We have integrated these approaches into Libra, a toolset for scalable load-balance analysis. We present Libra and show how it can be used to analyze data from large scientific applications scalably.

  13. The implications of linking the dynamic performance and turnover literatures.

    PubMed

    Sturman, M C; Trevor, C O

    2001-08-01

    This article examines how the literatures of dynamic performance and the performance-turnover relationship inform each other. The nonrandom performance turnover relationship suggests that dynamic performance studies may be biased by their elimination of participants who do not remain for the entire study period. The authors demonstrated that the performance slopes of those who leave an organization differ from the performance slopes of those who remain. This finding suggests that studies of the performance-turnover relationship need to consider employee performance trends when predicting turnover. Replicating and extending the research of D. A. Harrison, M. Virick, and S. William (1996), the authors found that performance changes from the previous month and performance trends measured over a longer time period explained variance in voluntary turnover beyond current performance. Finally, the authors showed that performance trends interacted with current performance in the prediction of voluntary turnover. PMID:11519652

  14. Dynamics and performance of clock pendulums

    NASA Astrophysics Data System (ADS)

    Hoyng, Peter

    2014-11-01

    We analyze the dynamics of a driven, damped pendulum as used in mechanical clocks. We derive equations for the amplitude and phase of the oscillation, on time scales longer than the pendulum period. The equations are first order ODEs and permit fast simulations of the joint effects of circular and escapement errors, friction, and other disturbances for long times. The equations contain two averages of the driving torque over a period, so that the results are not very sensitive to the "fine structure" of the driving. We adopt a constant-torque escapement and study the stationary pendulum rate as a function of driving torque and friction. We also study the reaction of the pendulum to a sudden change in the driving torque, and to stationary noisy driving. The equations for the amplitude and phase are shown to describe the pendulum dynamics quite well on time scales of one period and longer. Our emphasis is on a clear exposition of the physics.

  15. NERVA 400E thrust train dynamic analysis

    NASA Technical Reports Server (NTRS)

    Vronay, D. F.

    1972-01-01

    The natural frequencies and dynamic responses of the NERVA 400E engine thrust train were determined for nuclear space operations (NSO), and earth-orbital shuttle (EOS) during launch and boost conditions. For NSO, a mini-tank configuration was analyzed with the forward end of the upper truss assumed fixed at the stage/mini-tank interface. For EOS, both a mini-tank and an engine only configuration were analyzed for a specific engine assembly support (EAS) stiffness. For all cases the effect of the shield on dynamic response characteristics was determined by performing parallel analyses with and without the shield. Gimbaling loads were not generated as that effort was scheduled after the termination date. The analysis, while demonstrating the adequacy of the engine design, revealed serious deficiencies in the EAS. Responses at the unsupported ends of the engine are excessive. Responses at the nuclear subsystem interface appear acceptable. It is recommended that additional analysis and design effort be expended upon the EAS to ensure that all engine responses stay within reasonable bounds.

  16. Performance Analysis on Fault Tolerant Control System

    NASA Technical Reports Server (NTRS)

    Shin, Jong-Yeob; Belcastro, Christine

    2005-01-01

    In a fault tolerant control (FTC) system, a parameter varying FTC law is reconfigured based on fault parameters estimated by fault detection and isolation (FDI) modules. FDI modules require some time to detect fault occurrences in aero-vehicle dynamics. In this paper, an FTC analysis framework is provided to calculate the upper bound of an induced-L(sub 2) norm of an FTC system with existence of false identification and detection time delay. The upper bound is written as a function of a fault detection time and exponential decay rates and has been used to determine which FTC law produces less performance degradation (tracking error) due to false identification. The analysis framework is applied for an FTC system of a HiMAT (Highly Maneuverable Aircraft Technology) vehicle. Index Terms fault tolerant control system, linear parameter varying system, HiMAT vehicle.

  17. Passivhaus: indoor comfort and energy dynamic analysis.

    NASA Astrophysics Data System (ADS)

    Guida, Antonella; Pagliuca, Antonello; Cardinale, Nicola; Rospi, Gianluca

    2013-04-01

    The research aims to verify the energy performance as well as the indoor comfort of an energy class A+ building, built so that the sum of the heat passive contributions of solar radiation, transmitted through the windows, and the heat generated inside the building, are adeguate to compensate for the envelope loss during the cold season. The building, located in Emilia Romagna (Italy), was built using a wooden structure, an envelope realized using a pinewood sandwich panels (transmittance U = 0.250 W/m2K) and, inside, a wool flax insulation layer and thermal window frame with low-emissivity glass (U = 0524 W/m2K). The building design and construction process has followed the guidelines set by "CasaClima". The building has been modeled in the code of dynamic calculation "Energy Plus" by the Design Builder application and divided it into homogenous thermal zones, characterized by winter indoor temperature set at 20 ° (+ / - 1 °) and summer indoor temperature set at 26 ° (+ / - 1 °). It has modeled: the envelope, as described above, the "free" heat contributions, the air conditioning system, the Mechanical Ventilation system as well as home automation solutions. The air conditioning system is an heat pump, able to guarantee an optimization of energy consumption (in fact, it uses the "free" heat offered by the external environment for conditioning indoor environment). As regards the air recirculation system, it has been used a mechanical ventilation system with internal heat cross-flow exchanger, with an efficiency equal to 50%. The domotic solutions, instead, regard a system for the control of windows external screening using reeds, adjustable as a function of incident solar radiation and a lighting management system adjusted automatically using a dimmer. A so realized building meets the requirement imposed from Italian standard UNI/TS 11300 1, UNI/TS 11300 2 and UNI/TS 11300 3. The analysis was performed according to two different configurations: in "spontaneous

  18. MUSE instrument global performance analysis

    NASA Astrophysics Data System (ADS)

    Loupias, M.; Bacon, R.; Caillier, P.; Fleischmann, A.; Jarno, A.; Kelz, A.; Kosmalski, J.; Laurent, F.; Le Floch, M.; Lizon, J. L.; Manescau, A.; Nicklas, H.; Parès, L.; Pécontal, A.; Reiss, R.; Remillieux, A.; Renault, E.; Roth, M. M.; Rupprecht, G.; Stuik, R.

    2010-07-01

    MUSE (Multi Unit Spectroscopic Explorer) is a second generation instrument developed for ESO (European Southern Observatory) and will be assembled to the VLT (Very Large Telescope) in 2012. The MUSE instrument can simultaneously record 90.000 spectra in the visible wavelength range (465-930nm), across a 1*1arcmin2 field of view, thanks to 24 identical Integral Field Units (IFU). A collaboration of 7 institutes has successfully passed the Final Design Review and is currently working on the first sub-assemblies. The sharing of performances has been based on 5 main functional sub-systems. The Fore Optics sub-system derotates and anamorphoses the VLT Nasmyth focal plane image, the Splitting and Relay Optics associated with the Main Structure are feeding each IFU with 1/24th of the field of view. Each IFU is composed of a 3D function insured by an image slicer system and a spectrograph, and a detection function by a 4k*4k CCD cooled down to 163°K. The 5th function is the calibration and data reduction of the instrument. This article depicts the breakdown of performances between these sub-systems (throughput, image quality...), and underlines the constraining parameters of the interfaces either internal or with the VLT. The validation of all these requirements is a critical task started a few months ago which requires a clear traceability and performances analysis.

  19. Metaconcrete: Engineered aggregates for enhanced dynamic performance

    NASA Astrophysics Data System (ADS)

    Mitchell, Stephanie J.

    This work presents the development and investigation of a new type of concrete for the attenuation of waves induced by dynamic excitation. Recent progress in the field of metamaterials science has led to a range of novel composites which display unusual properties when interacting with electromagnetic, acoustic, and elastic waves. A new structural metamaterial with enhanced properties for dynamic loading applications is presented, which is named metaconcrete. In this new composite material the standard stone and gravel aggregates of regular concrete are replaced with spherical engineered inclusions. Each metaconcrete aggregate has a layered structure, consisting of a heavy core and a thin compliant outer coating. This structure allows for resonance at or near the eigenfrequencies of the inclusions, and the aggregates can be tuned so that resonant oscillations will be activated by particular frequencies of an applied dynamic loading. The activation of resonance within the aggregates causes the overall system to exhibit negative effective mass, which leads to attenuation of the applied wave motion. To investigate the behavior of metaconcrete slabs under a variety of different loading conditions a finite element slab model containing a periodic array of aggregates is utilized. The frequency dependent nature of metaconcrete is investigated by considering the transmission of wave energy through a slab, which indicates the presence of large attenuation bands near the resonant frequencies of the aggregates. Applying a blast wave loading to both an elastic slab and a slab model that incorporates the fracture characteristics of the mortar matrix reveals that a significant portion of the supplied energy can be absorbed by aggregates which are activated by the chosen blast wave profile. The transfer of energy from the mortar matrix to the metaconcrete aggregates leads to a significant reduction in the maximum longitudinal stress, greatly improving the ability of the material

  20. Manufacturing in space: Fluid dynamics numerical analysis

    NASA Technical Reports Server (NTRS)

    Robertson, S. J.; Nicholson, L. A.; Spradley, L. W.

    1981-01-01

    Natural convection in a spherical container with cooling at the center was numerically simulated using the Lockheed-developed General Interpolants Method (GIM) numerical fluid dynamic computer program. The numerical analysis was simplified by assuming axisymmetric flow in the spherical container, with the symmetry axis being a sphere diagonal parallel to the gravity vector. This axisymmetric spherical geometry was intended as an idealization of the proposed Lal/Kroes growing experiments to be performed on board Spacelab. Results were obtained for a range of Rayleigh numbers from 25 to 10,000. For a temperature difference of 10 C from the cooling sting at the center to the container surface, and a gravitional loading of 0.000001 g a computed maximum fluid velocity of about 2.4 x 0.00001 cm/sec was reached after about 250 sec. The computed velocities were found to be approximately proportional to the Rayleigh number over the range of Rayleigh numbers investigated.

  1. Guidelines for dynamic data acquisition and analysis

    NASA Technical Reports Server (NTRS)

    Piersol, Allan G.

    1992-01-01

    The recommendations concerning pyroshock data presented in the final draft of a proposed military handbook on Guidelines for Dynamic Data Acquisition and Analysis are reviewed. The structural responses produced by pyroshocks are considered to be one of the most difficult types of dynamic data to accurately measure and analyze.

  2. Guidelines for dynamic data acquisition and analysis

    NASA Astrophysics Data System (ADS)

    Piersol, Allan G.

    1992-10-01

    The recommendations concerning pyroshock data presented in the final draft of a proposed military handbook on Guidelines for Dynamic Data Acquisition and Analysis are reviewed. The structural responses produced by pyroshocks are considered to be one of the most difficult types of dynamic data to accurately measure and analyze.

  3. Bimolecular dynamics by computer analysis

    SciTech Connect

    Eilbeck, J.C.; Lomdahl, P.S.; Scott, A.C.

    1984-01-01

    As numerical tools (computers and display equipment) become more powerful and the atomic structures of important biological molecules become known, the importance of detailed computation of nonequilibrium biomolecular dynamics increases. In this manuscript we report results from a well developed study of the hydrogen bonded polypeptide crystal acetanilide, a model protein. Directions for future research are suggested. 9 references, 6 figures.

  4. Unsupervised analysis of small animal dynamic Cerenkov luminescence imaging

    NASA Astrophysics Data System (ADS)

    Spinelli, Antonello E.; Boschi, Federico

    2011-12-01

    Clustering analysis (CA) and principal component analysis (PCA) were applied to dynamic Cerenkov luminescence images (dCLI). In order to investigate the performances of the proposed approaches, two distinct dynamic data sets obtained by injecting mice with 32P-ATP and 18F-FDG were acquired using the IVIS 200 optical imager. The k-means clustering algorithm has been applied to dCLI and was implemented using interactive data language 8.1. We show that cluster analysis allows us to obtain good agreement between the clustered and the corresponding emission regions like the bladder, the liver, and the tumor. We also show a good correspondence between the time activity curves of the different regions obtained by using CA and manual region of interest analysis on dCLIT and PCA images. We conclude that CA provides an automatic unsupervised method for the analysis of preclinical dynamic Cerenkov luminescence image data.

  5. Analysis of dynamic multiplicity fluctuations at PHOBOS

    NASA Astrophysics Data System (ADS)

    Chai, Zhengwei; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J. L.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wolfs, F. L. H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A. H.; Wyslouch, B.

    2005-01-01

    This paper presents the analysis of the dynamic fluctuations in the inclusive charged particle multiplicity measured by PHOBOS for Au+Au collisions at surdsNN = 200GeV within the pseudo-rapidity range of -3 < η < 3. First the definition of the fluctuations observables used in this analysis is presented, together with the discussion of their physics meaning. Then the procedure for the extraction of dynamic fluctuations is described. Some preliminary results are included to illustrate the correlation features of the fluctuation observable. New dynamic fluctuations results will be available in a later publication.

  6. Detrended fluctuation analysis of heart intrabeat dynamics

    NASA Astrophysics Data System (ADS)

    Rodriguez, Eduardo; Echeverria, Juan C.; Alvarez-Ramirez, Jose

    2007-10-01

    We investigate scaling properties of electrocardiogram (ECG) recordings of healthy subjects and heart failure patients based on detrended fluctuation analysis (DFA). While the vast majority of scaling analysis has focused on the characterization of the long-range correlations of interbeat (i.e., beat-to-beat) dynamics, in this work we consider instead the characterization of intrabeat dynamics. That is, here we use DFA to study correlations for time scales smaller than one heart beat period (about 0.75 s). Our results show that intrabeat dynamics of healthy subject are less correlated than for heart failure dynamics. As in the case of interbeat dynamics, the DFA scaling exponents can be used to discriminate healthy and pathological data. It is shown that 0.5 h recordings suffices to characterize the ECG correlation properties.

  7. Stirred media mills: Dynamics, performance, and physio-chemical aspects

    NASA Astrophysics Data System (ADS)

    Zheng, Jie

    While applications of stirred media mills for fine particle production have continued to grow, there is a lack of understanding of power requirements, optimum operating conditions and powder (product) characteristics underlying stirred media milling processes. To develop a physical understanding of stirred mill dynamics and scale-up principles, and to identify conditions and mechanisms for effective use of energy in fine grinding, the results of analysis of the literature and of tests in laboratory stirred media mills with media, limestone, and the effect of chemical additives as grinding aids are presented, and mill dynamics, performance and physico-chemical aspects are discussed. Four operational regions marked by sharp transitions are described: transition from static to dynamic friction; channeling; dispersion; and centrifugation. Equations, including power and modified Reynolds number, have been established for relating relevant operating and geometrical variables. Scale-up guidelines with respect to power consumption are also proposed. The best operating conditions for grinding limestone have been identified. The effect of additives on the grinding efficiency and the properties of ground product is discussed using the example of ultra fine grinding of limestone, in which more than a 100% increase in specific surface area and energy efficiency can be obtained. As solid concentration increases, media/pulp flow patterns pass through four regimes: vortex flow, rotating flow, layer formation above the impeller pins, and layer formation adjacent to the tank wall. Use of polyacrylic acid as an additive caused the media/pulp flow to move toward lower solid concentration situation, thus improving grinding conditions and resulting in better grinding. Fragmentation of the polymer molecules was found to occur during long term grinding and this was beneficial for ultrafine grinding. In summary, the research has led to the development of a physical understanding of mill

  8. Approaches to Cycle Analysis and Performance Metrics

    NASA Technical Reports Server (NTRS)

    Parson, Daniel E.

    2003-01-01

    The following notes were prepared as part of an American Institute of Aeronautics and Astronautics (AIAA) sponsored short course entitled Air Breathing Pulse Detonation Engine (PDE) Technology. The course was presented in January of 2003, and again in July of 2004 at two different AIAA meetings. It was taught by seven instructors, each of whom provided information on particular areas of PDE research. These notes cover two areas. The first is titled Approaches to Cycle Analysis and Performance Metrics. Here, the various methods of cycle analysis are introduced. These range from algebraic, thermodynamic equations, to single and multi-dimensional Computational Fluid Dynamic (CFD) solutions. Also discussed are the various means by which performance is measured, and how these are applied in a device which is fundamentally unsteady. The second topic covered is titled PDE Hybrid Applications. Here the concept of coupling a PDE to a conventional turbomachinery based engine is explored. Motivation for such a configuration is provided in the form of potential thermodynamic benefits. This is accompanied by a discussion of challenges to the technology.

  9. NERVA dynamic analysis methodology, SPRVIB

    NASA Technical Reports Server (NTRS)

    Vronay, D. F.

    1972-01-01

    The general dynamic computer code called SPRVIB (Spring Vib) developed in support of the NERVA (nuclear engine for rocket vehicle application) program is described. Using normal mode techniques, the program computes kinematical responses of a structure caused by various combinations of harmonic and elliptic forcing functions or base excitations. Provision is made for a graphical type of force or base excitation input to the structure. A description of the required input format and a listing of the program are presented, along with several examples illustrating the use of the program. SPRVIB is written in FORTRAN 4 computer language for use on the CDC 6600 or the IBM 360/75 computers.

  10. Nonlinear Analysis Of Rotor Dynamics

    NASA Technical Reports Server (NTRS)

    Day, William B.; Zalik, Richard

    1988-01-01

    Study explores analytical consequences of nonlinear Jeffcott equations of rotor dynamics. Section 1: Summary of previous studies. Section 2: Jeffcott Equations. Section 3: Proves two theorems that provide inequalities on coefficients of differential equations and magnitude of forcing function in absence of side force. Section 4: Numerical investigation of multiple-forcing-function problem by introducing both side force and mass imbalance. Section 5: Examples of numberical solutions of complex generalized Jeffcott equation with two forcing functions of different frequencies f1 and f2. Section 6: Boundedness and stability of solutions.Section 7: Concludes report reviewing analytical results and significance.

  11. PERFORMANCE ANALYSIS OF MECHANICAL DRAFT COOLING TOWER

    SciTech Connect

    Lee, S; Alfred Garrett, A; James02 Bollinger, J; Larry Koffman, L

    2009-02-10

    Industrial processes use mechanical draft cooling towers (MDCT's) to dissipate waste heat by transferring heat from water to air via evaporative cooling, which causes air humidification. The Savannah River Site (SRS) has cross-flow and counter-current MDCT's consisting of four independent compartments called cells. Each cell has its own fan to help maximize heat transfer between ambient air and circulated water. The primary objective of the work is to simulate the cooling tower performance for the counter-current cooling tower and to conduct a parametric study under different fan speeds and ambient air conditions. The Savannah River National Laboratory (SRNL) developed a computational fluid dynamics (CFD) model and performed the benchmarking analysis against the integral measurement results to accomplish the objective. The model uses three-dimensional steady-state momentum, continuity equations, air-vapor species balance equation, and two-equation turbulence as the basic governing equations. It was assumed that vapor phase is always transported by the continuous air phase with no slip velocity. In this case, water droplet component was considered as discrete phase for the interfacial heat and mass transfer via Lagrangian approach. Thus, the air-vapor mixture model with discrete water droplet phase is used for the analysis. A series of parametric calculations was performed to investigate the impact of wind speeds and ambient conditions on the thermal performance of the cooling tower when fans were operating and when they were turned off. The model was also benchmarked against the literature data and the SRS integral test results for key parameters such as air temperature and humidity at the tower exit and water temperature for given ambient conditions. Detailed results will be published here.

  12. Wavelet spectrum analysis approach to model validation of dynamic systems

    NASA Astrophysics Data System (ADS)

    Jiang, Xiaomo; Mahadevan, Sankaran

    2011-02-01

    Feature-based validation techniques for dynamic system models could be unreliable for nonlinear, stochastic, and transient dynamic behavior, where the time series is usually non-stationary. This paper presents a wavelet spectral analysis approach to validate a computational model for a dynamic system. Continuous wavelet transform is performed on the time series data for both model prediction and experimental observation using a Morlet wavelet function. The wavelet cross-spectrum is calculated for the two sets of data to construct a time-frequency phase difference map. The Box-plot, an exploratory data analysis technique, is applied to interpret the phase difference for validation purposes. In addition, wavelet time-frequency coherence is calculated using the locally and globally smoothed wavelet power spectra of the two data sets. Significance tests are performed to quantitatively verify whether the wavelet time-varying coherence is significant at a specific time and frequency point, considering uncertainties in both predicted and observed time series data. The proposed wavelet spectrum analysis approach is illustrated with a dynamics validation challenge problem developed at the Sandia National Laboratories. A comparison study is conducted to demonstrate the advantages of the proposed methodologies over classical frequency-independent cross-correlation analysis and time-independent cross-coherence analysis for the validation of dynamic systems.

  13. Analysis of Multidomain Protein Dynamics.

    PubMed

    Roy, Amitava; Hua, Duy P; Post, Carol Beth

    2016-01-12

    Proteins with a modular architecture of multiple domains connected by linkers often exhibit diversity in the relative positions of domains, while the domain tertiary structure remains unchanged. The biological function of these modular proteins, or the regulation of their activity, depends on the variation in domain orientation and separation. Accordingly, careful characterization of interdomain motion and correlated fluctuations of multidomain systems is relevant for understanding the functional behavior of modular proteins. Molecular dynamics (MD) simulations provides a powerful approach to study these motions in atomic detail. Nevertheless, the common procedure for analyzing fluctuations from MD simulations after rigid-body alignment fails for multidomain proteins; it greatly overestimates correlated positional fluctuations in the presence of relative domain motion. We show here that expressing the atomic motions of a multidomain protein as a combination of displacement within the domain reference frame and motion of the relative domains correctly separates the internal motions to allow a useful description of correlated fluctuations. We illustrate the methodology of separating the domain fluctuations and local fluctuations by application to the tandem SH2 domains of human Syk protein kinase and by characterizing an effect of phosphorylation on the dynamics. Correlated motions are assessed from a distance covariance rather than the more common vector-coordinate covariance. The approach makes it possible to calculate the proper correlations in fluctuations internal to a domain as well as between domains. PMID:26675644

  14. Nonlinear Dynamical Analysis of Fibrillation

    NASA Astrophysics Data System (ADS)

    Kerin, John A.; Sporrer, Justin M.; Egolf, David A.

    2013-03-01

    The development of spatiotemporal chaotic behavior in heart tissue, termed fibrillation, is a devastating, life-threatening condition. The chaotic behavior of electrochemical signals, in the form of spiral waves, causes the muscles of the heart to contract in an incoherent manner, hindering the heart's ability to pump blood. We have applied the mathematical tools of nonlinear dynamics to large-scale simulations of a model of fibrillating heart tissue to uncover the dynamical modes driving this chaos. By studying the evolution of Lyapunov vectors and exponents over short times, we have found that the fibrillating tissue is sensitive to electrical perturbations only in narrow regions immediately in front of the leading edges of spiral waves, especially when these waves collide, break apart, or hit the edges of the tissue sample. Using this knowledge, we have applied small stimuli to areas of varying sensitivity. By studying the evolution of the effects of these perturbations, we have made progress toward controlling the electrochemical patterns associated with heart fibrillation. This work was supported by the U.S. National Science Foundation (DMR-0094178) and Research Corporation.

  15. SPAR improved structure-fluid dynamic analysis capability, phase 2

    NASA Technical Reports Server (NTRS)

    Pearson, M. L.

    1984-01-01

    An efficient and general method of analyzing a coupled dynamic system of fluid flow and elastic structures is investigated. The improvement of Structural Performance Analysis and Redesign (SPAR) code is summarized. All error codes are documented and the SPAR processor/subroutine cross reference is included.

  16. Onsite analysis of data from the Dynamics Explorer (DE) spacecraft

    NASA Technical Reports Server (NTRS)

    Fung, Shing F.; Candey, Robert M.; Humphreys, Josephine N.

    1992-01-01

    The tasks performed by ARC Professional Services Group, Inc. fell into five parts: (1) dynamics explorer (DE) data analysis and modeling; (2) DE project support; (3) chemical release observations support; (4) VLF emissions and plasma instability studies; and (5) modeling of planetary radio emissions. Some recommendations for future considerations are also addressed.

  17. Incentives and Their Dynamics in Public Sector Performance Management Systems

    ERIC Educational Resources Information Center

    Heinrich, Carolyn J.; Marschke, Gerald

    2010-01-01

    We use the principal-agent model as a focal theoretical frame for synthesizing what we know, both theoretically and empirically, about the design and dynamics of the implementation of performance management systems in the public sector. In this context, we review the growing body of evidence about how performance measurement and incentive systems…

  18. Developmental Dynamics of Math Performance From Preschool to Grade 2

    ERIC Educational Resources Information Center

    Aunola, Kaisa; Leskinen, Esko; Lerkkanen, Marja-Kristiina; Nurmi, Jari-Erik

    2004-01-01

    This study investigated the developmental dynamics of mathematical performance during children's transition from preschool to Grade 2 and the cognitive antecedents of this development. 194 Finnish children were examined 6 times according to their math performance, twice during each year across a 3-year period. Cognitive antecedents, that is,…

  19. Traffic chaotic dynamics modeling and analysis of deterministic network

    NASA Astrophysics Data System (ADS)

    Wu, Weiqiang; Huang, Ning; Wu, Zhitao

    2016-07-01

    Network traffic is an important and direct acting factor of network reliability and performance. To understand the behaviors of network traffic, chaotic dynamics models were proposed and helped to analyze nondeterministic network a lot. The previous research thought that the chaotic dynamics behavior was caused by random factors, and the deterministic networks would not exhibit chaotic dynamics behavior because of lacking of random factors. In this paper, we first adopted chaos theory to analyze traffic data collected from a typical deterministic network testbed — avionics full duplex switched Ethernet (AFDX, a typical deterministic network) testbed, and found that the chaotic dynamics behavior also existed in deterministic network. Then in order to explore the chaos generating mechanism, we applied the mean field theory to construct the traffic dynamics equation (TDE) for deterministic network traffic modeling without any network random factors. Through studying the derived TDE, we proposed that chaotic dynamics was one of the nature properties of network traffic, and it also could be looked as the action effect of TDE control parameters. A network simulation was performed and the results verified that the network congestion resulted in the chaotic dynamics for a deterministic network, which was identical with expectation of TDE. Our research will be helpful to analyze the traffic complicated dynamics behavior for deterministic network and contribute to network reliability designing and analysis.

  20. Visual Analysis of Dynamic Data Streams

    SciTech Connect

    Chin, George; Singhal, Mudita; Nakamura, Grant C.; Gurumoorthi, Vidhya; Freeman-Cadoret, Natalie A.

    2009-09-01

    For scientific data visualizations, real-time data streams present many interesting challenges when compared to static data. Real-time data are dynamic, transient, high-volume, and temporal. Effective visualizations need to be able to accommodate dynamic data behavior as well as abstract and present the data in ways that make sense to and are usable by humans. The Visual Content Analysis of Real-Time Data Streams project at the Pacific Northwest National Laboratory is researching and prototyping dynamic visualization techniques and tools to help facilitate human understanding and comprehension of high-volume, real-time data. The general strategy of the project is to develop and evolve visual contexts that will organize and orient complex dynamic data in conceptual and perceptive views. The goal is to allow users to quickly grasp dynamic data in forms that are intuitive and natural without requiring intensive training in the use of specific visualization or analysis tools and methods. Thus far, the project has prototyped four different visualization prototypes that represents and convey dynamic data through human-recognizable contexts and paradigms such as hierarchies, relationships, time, and geography. We describe the design considerations and unique features of these dynamic visualization prototypes as well as our findings in the exploration and evaluation of their use.

  1. SEP thrust subsystem performance sensitivity analysis

    NASA Technical Reports Server (NTRS)

    Atkins, K. L.; Sauer, C. G., Jr.; Kerrisk, D. J.

    1973-01-01

    This is a two-part report on solar electric propulsion (SEP) performance sensitivity analysis. The first part describes the preliminary analysis of the SEP thrust system performance for an Encke rendezvous mission. A detailed description of thrust subsystem hardware tolerances on mission performance is included together with nominal spacecraft parameters based on these tolerances. The second part describes the method of analysis and graphical techniques used in generating the data for Part 1. Included is a description of both the trajectory program used and the additional software developed for this analysis. Part 2 also includes a comprehensive description of the use of the graphical techniques employed in this performance analysis.

  2. Dynamic Systems Analysis for Turbine Based Aero Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Csank, Jeffrey T.

    2016-01-01

    The aircraft engine design process seeks to optimize the overall system-level performance, weight, and cost for a given concept. Steady-state simulations and data are used to identify trade-offs that should be balanced to optimize the system in a process known as systems analysis. These systems analysis simulations and data may not adequately capture the true performance trade-offs that exist during transient operation. Dynamic systems analysis provides the capability for assessing the dynamic tradeoffs at an earlier stage of the engine design process. The dynamic systems analysis concept, developed tools, and potential benefit are presented in this paper. To provide this capability, the Tool for Turbine Engine Closed-loop Transient Analysis (TTECTrA) was developed to provide the user with an estimate of the closed-loop performance (response time) and operability (high pressure compressor surge margin) for a given engine design and set of control design requirements. TTECTrA along with engine deterioration information, can be used to develop a more generic relationship between performance and operability that can impact the engine design constraints and potentially lead to a more efficient engine.

  3. Structural Dynamics and Data Analysis

    NASA Technical Reports Server (NTRS)

    Luthman, Briana L.

    2013-01-01

    This project consists of two parts, the first will be the post-flight analysis of data from a Delta IV launch vehicle, and the second will be a Finite Element Analysis of a CubeSat. Shock and vibration data was collected on WGS-5 (Wideband Global SATCOM- 5) which was launched on a Delta IV launch vehicle. Using CAM (CAlculation with Matrices) software, the data is to be plotted into Time History, Shock Response Spectrum, and SPL (Sound Pressure Level) curves. In this format the data is to be reviewed and compared to flight instrumentation data from previous flights of the same launch vehicle. This is done to ensure the current mission environments, such as shock, random vibration, and acoustics, are not out of family with existing flight experience. In family means the peaks on the SRS curve for WGS-5 are similar to the peaks from the previous flights and there are no major outliers. The curves from the data will then be compiled into a useful format so that is can be peer reviewed then presented before an engineering review board if required. Also, the reviewed data will be uploaded to the Engineering Review Board Information System (ERBIS) to archive. The second part of this project is conducting Finite Element Analysis of a CubeSat. In 2010, Merritt Island High School partnered with NASA to design, build and launch a CubeSat. The team is now called StangSat in honor of their mascot, the mustang. Over the past few years, the StangSat team has built a satellite and has now been manifested for flight on a SpaceX Falcon 9 launch in 2014. To prepare for the final launch, a test flight was conducted in Mojave, California. StangSat was launched on a Prospector 18D, a high altitude rocket made by Garvey Spacecraft Corporation, along with their sister satellite CP9 built by California Polytechnic University. However, StangSat was damaged during an off nominal landing and this project will give beneficial insights into what loads the CubeSat experienced during the crash

  4. 4D Dynamic Required Navigation Performance Final Report

    NASA Technical Reports Server (NTRS)

    Finkelsztein, Daniel M.; Sturdy, James L.; Alaverdi, Omeed; Hochwarth, Joachim K.

    2011-01-01

    New advanced four dimensional trajectory (4DT) procedures under consideration for the Next Generation Air Transportation System (NextGen) require an aircraft to precisely navigate relative to a moving reference such as another aircraft. Examples are Self-Separation for enroute operations and Interval Management for in-trail and merging operations. The current construct of Required Navigation Performance (RNP), defined for fixed-reference-frame navigation, is not sufficiently specified to be applicable to defining performance levels of such air-to-air procedures. An extension of RNP to air-to-air navigation would enable these advanced procedures to be implemented with a specified level of performance. The objective of this research effort was to propose new 4D Dynamic RNP constructs that account for the dynamic spatial and temporal nature of Interval Management and Self-Separation, develop mathematical models of the Dynamic RNP constructs, "Required Self-Separation Performance" and "Required Interval Management Performance," and to analyze the performance characteristics of these air-to-air procedures using the newly developed models. This final report summarizes the activities led by Raytheon, in collaboration with GE Aviation and SAIC, and presents the results from this research effort to expand the RNP concept to a dynamic 4D frame of reference.

  5. Performance impact of dynamic parallelism on different clustering algorithms

    NASA Astrophysics Data System (ADS)

    DiMarco, Jeffrey; Taufer, Michela

    2013-05-01

    In this paper, we aim to quantify the performance gains of dynamic parallelism. The newest version of CUDA, CUDA 5, introduces dynamic parallelism, which allows GPU threads to create new threads, without CPU intervention, and adapt to its data. This effectively eliminates the superfluous back and forth communication between the GPU and CPU through nested kernel computations. The change in performance will be measured using two well-known clustering algorithms that exhibit data dependencies: the K-means clustering and the hierarchical clustering. K-means has a sequential data dependence wherein iterations occur in a linear fashion, while the hierarchical clustering has a tree-like dependence that produces split tasks. Analyzing the performance of these data-dependent algorithms gives us a better understanding of the benefits or potential drawbacks of CUDA 5's new dynamic parallelism feature.

  6. Analysis of Costs and Performance

    ERIC Educational Resources Information Center

    Duchesne, Roderick M.

    1973-01-01

    This article outlines a library management information system concerned with total library costs and performance. The system is essentially an adaptation of well-proven industrial and commercial management accounting techniques to the library context. (24 references) (Author)

  7. A dynamic human motion: coordination analysis.

    PubMed

    Pchelkin, Stepan; Shiriaev, Anton S; Freidovich, Leonid B; Mettin, Uwe; Gusev, Sergei V; Kwon, Woong; Paramonov, Leonid

    2015-02-01

    This article is concerned with the generic structure of the motion coordination system resulting from the application of the method of virtual holonomic constraints (VHCs) to the problem of the generation and robust execution of a dynamic humanlike motion by a humanoid robot. The motion coordination developed using VHCs is based on a motion generator equation, which is a scalar nonlinear differential equation of second order. It can be considered equivalent in function to a central pattern generator in living organisms. The relative time evolution of the degrees of freedom of a humanoid robot during a typical motion are specified by a set of coordination functions that uniquely define the overall pattern of the motion. This is comparable to a hypothesis on the existence of motion patterns in biomechanics. A robust control is derived based on a transverse linearization along the configuration manifold defined by the coordination functions. It is shown that the derived coordination and control architecture possesses excellent robustness properties. The analysis is performed on an example of a real human motion recorded in test experiments. PMID:25158624

  8. Guided wave tomography performance analysis

    NASA Astrophysics Data System (ADS)

    Huthwaite, Peter; Lowe, Michael; Cawley, Peter

    2016-02-01

    Quantifying wall loss caused by corrosion is a significant challenge for the petrochemical industry. Corrosion commonly occurs at pipe supports, where surface access for inspection is limited. Guided wave tomography is pursued as a solution to this: guided waves are transmitted through the region of interest from an array, and tomographic reconstruction techniques are applied to the measured signals in order to produce a map of thickness. There are many parameters in the system which can affect the performance; this paper investigates how the accuracy varies as defect width and depth, operating frequency and guided wave mode are all changed. For the S0 mode, the best performance was seen around 170kHz on the 10mm plate, with poor performance seen at almost all other frequencies. A0 showed better performance across a broad range of frequencies, with resolution improving with frequency as the wavelength reduced. However, it was shown that the resolution limit did drop relative to the wavelength, limiting the performance at high frequencies slightly.

  9. SUBSONIC WIND TUNNEL PERFORMANCE ANALYSIS SOFTWARE

    NASA Technical Reports Server (NTRS)

    Eckert, W. T.

    1994-01-01

    This program was developed as an aid in the design and analysis of subsonic wind tunnels. It brings together and refines previously scattered and over-simplified techniques used for the design and loss prediction of the components of subsonic wind tunnels. It implements a system of equations for determining the total pressure losses and provides general guidelines for the design of diffusers, contractions, corners and the inlets and exits of non-return tunnels. The algorithms used in the program are applicable to compressible flow through most closed- or open-throated, single-, double- or non-return wind tunnels or ducts. A comparison between calculated performance and that actually achieved by several existing facilities produced generally good agreement. Any system through which air is flowing which involves turns, fans, contractions etc. (e.g., an HVAC system) may benefit from analysis using this software. This program is an update of ARC-11138 which includes PC compatibility and an improved user interface. The method of loss analysis used by the program is a synthesis of theoretical and empirical techniques. Generally, the algorithms used are those which have been substantiated by experimental test. The basic flow-state parameters used by the program are determined from input information about the reference control section and the test section. These parameters were derived from standard relationships for compressible flow. The local flow conditions, including Mach number, Reynolds number and friction coefficient are determined for each end of each component or section. The loss in total pressure caused by each section is calculated in a form non-dimensionalized by local dynamic pressure. The individual losses are based on the nature of the section, local flow conditions and input geometry and parameter information. The loss forms for typical wind tunnel sections considered by the program include: constant area ducts, open throat ducts, contractions, constant

  10. Adaptive Optics Communications Performance Analysis

    NASA Technical Reports Server (NTRS)

    Srinivasan, M.; Vilnrotter, V.; Troy, M.; Wilson, K.

    2004-01-01

    The performance improvement obtained through the use of adaptive optics for deep-space communications in the presence of atmospheric turbulence is analyzed. Using simulated focal-plane signal-intensity distributions, uncoded pulse-position modulation (PPM) bit-error probabilities are calculated assuming the use of an adaptive focal-plane detector array as well as an adaptively sized single detector. It is demonstrated that current practical adaptive optics systems can yield performance gains over an uncompensated system ranging from approximately 1 dB to 6 dB depending upon the PPM order and background radiation level.

  11. Computer program for flexible rotor dynamics analysis

    NASA Technical Reports Server (NTRS)

    Shen, F. A.

    1974-01-01

    Program analyzes general nonaxisymmetric and nonsynchronous transient and steady-state rotor dynamic performance of bending- and shear-wise flexible rotor-bearing system under various operating conditions. Program can be used as analytical study tool for general transient spin-speed and/or non-axisymmetric rotor motion.

  12. Dynamical coupled-channel analysis at EBAC.

    SciTech Connect

    Lee, T.-S. H.; Physics

    2008-01-01

    In this contribution, the author reports on the dynamical coupled-channels analysis being pursued at the Excited Baryon Analysis Center (EBAC) of Jefferson Laboratory. EBAC was established in January 2006. Its objective is to extract the parameters associated with the excited states (N*) of the nucleon from the world data of meson production reactions, and to also develop theoretical interpretations of the extracted N* parameters.

  13. Dynamic analysis for shuttle design verification

    NASA Technical Reports Server (NTRS)

    Fralich, R. W.; Green, C. E.; Rheinfurth, M. H.

    1972-01-01

    Two approaches that are used for determining the modes and frequencies of space shuttle structures are discussed. The first method, direct numerical analysis, involves finite element mathematical modeling of the space shuttle structure in order to use computer programs for dynamic structural analysis. The second method utilizes modal-coupling techniques of experimental verification made by vibrating only spacecraft components and by deducing modes and frequencies of the complete vehicle from results obtained in the component tests.

  14. Structural-Thermal-Optical-Performance (STOP) Analysis

    NASA Technical Reports Server (NTRS)

    Bolognese, Jeffrey; Irish, Sandra

    2015-01-01

    The presentation will be given at the 26th Annual Thermal Fluids Analysis Workshop (TFAWS 2015) hosted by the Goddard Spaceflight Center (GSFC) Thermal Engineering Branch (Code 545). A STOP analysis is a multidiscipline analysis, consisting of Structural, Thermal and Optical Performance Analyses, that is performed for all space flight instruments and satellites. This course will explain the different parts of performing this analysis. The student will learn how to effectively interact with each discipline in order to accurately obtain the system analysis results.

  15. Final Report Computational Analysis of Dynamical Systems

    SciTech Connect

    Guckenheimer, John

    2012-05-08

    This is the final report for DOE Grant DE-FG02-93ER25164, initiated in 1993. This grant supported research of John Guckenheimer on computational analysis of dynamical systems. During that period, seventeen individuals received PhD degrees under the supervision of Guckenheimer and over fifty publications related to the grant were produced. This document contains copies of these publications.

  16. Dynamic replanning on demand of UAS constellations performing ISR missions

    NASA Astrophysics Data System (ADS)

    Stouch, Daniel W.; Zeidman, Ernest; Callahan, William; McGraw, Kirk

    2011-05-01

    Unmanned aerial systems (UAS) have proven themselves to be indispensable in providing intelligence, surveillance, and reconnaissance (ISR) over the battlefield. Constellations of heterogeneous, multi-purpose UAS are being tasked to provide ISR in an unpredictable environment. This necessitates the dynamic replanning of critical missions as weather conditions change, new observation targets are identified, aircraft are lost or equipment malfunctions, and new airspace restrictions are introduced. We present a method to generate coordinated mission plans for constellations of UAS with multiple flight goals and potentially competing objectives, and update them on demand as the operational situation changes. We use a fast evolutionary algorithm-based, multi-objective optimization technique. The updated flight routes maintain continuity by considering where the ISR assets have already flown and where they still need to go. Both the initial planning and replanning take into account factors such as area of analysis coverage, restricted operating zones, maximum control station range, adverse weather effects, military terrain value, and sensor performance. Our results demonstrate that by constraining the space of potential solutions using an intelligently-formed air maneuver network with a subset of potential airspace corridors and navigational waypoints, we can ensure global optimization for multiple objectives considering the situation both before and after the replanning is initiated. We employ sophisticated visualization techniques using a geographic information system to help the user 'look under the hood" of the algorithms to understand the effectiveness and viability of the generated ISR mission plans and identify potential gaps in coverage.

  17. Topological analysis of chaotic dynamical systems

    NASA Astrophysics Data System (ADS)

    Gilmore, Robert

    1998-10-01

    Topological methods have recently been developed for the analysis of dissipative dynamical systems that operate in the chaotic regime. They were originally developed for three-dimensional dissipative dynamical systems, but they are applicable to all ``low-dimensional'' dynamical systems. These are systems for which the flow rapidly relaxes to a three-dimensional subspace of phase space. Equivalently, the associated attractor has Lyapunov dimension dL<3. Topological methods supplement methods previously developed to determine the values of metric and dynamical invariants. However, topological methods possess three additional features: they describe how to model the dynamics; they allow validation of the models so developed; and the topological invariants are robust under changes in control-parameter values. The topological-analysis procedure depends on identifying the stretching and squeezing mechanisms that act to create a strange attractor and organize all the unstable periodic orbits in this attractor in a unique way. The stretching and squeezing mechanisms are represented by a caricature, a branched manifold, which is also called a template or a knot holder. This turns out to be a version of the dynamical system in the limit of infinite dissipation. This topological structure is identified by a set of integer invariants. One of the truly remarkable results of the topological-analysis procedure is that these integer invariants can be extracted from a chaotic time series. Furthermore, self-consistency checks can be used to confirm the integer values. These integers can be used to determine whether or not two dynamical systems are equivalent; in particular, they can determine whether a model developed from time-series data is an accurate representation of a physical system. Conversely, these integers can be used to provide a model for the dynamical mechanisms that generate chaotic data. In fact, the author has constructed a doubly discrete classification of strange

  18. Solar Dynamic Power System Stability Analysis and Control

    NASA Technical Reports Server (NTRS)

    Momoh, James A.; Wang, Yanchun

    1996-01-01

    The objective of this research is to conduct dynamic analysis, control design, and control performance test of solar power system. Solar power system consists of generation system and distribution network system. A bench mark system is used in this research, which includes a generator with excitation system and governor, an ac/dc converter, six DDCU's and forty-eight loads. A detailed model is used for modeling generator. Excitation system is represented by a third order model. DDCU is represented by a seventh order system. The load is modeled by the combination of constant power and constant impedance. Eigen-analysis and eigen-sensitivity analysis are used for system dynamic analysis. The effects of excitation system, governor, ac/dc converter control, and the type of load on system stability are discussed. In order to improve system transient stability, nonlinear ac/dc converter control is introduced. The direct linearization method is used for control design. The dynamic analysis results show that these controls affect system stability in different ways. The parameter coordination of controllers are recommended based on the dynamic analysis. It is concluded from the present studies that system stability is improved by the coordination of control parameters and the nonlinear ac/dc converter control stabilize system oscillation caused by the load change and system fault efficiently.

  19. Performance of statistical energy analysis

    NASA Technical Reports Server (NTRS)

    Davis, R. F.; Hines, D. E.

    1973-01-01

    Statistical energy analysis (SEA) methods have been developed for high frequency modal analyses on random vibration environments. These SEA methods are evaluated by comparing analytical predictions to test results. Simple test methods are developed for establishing SEA parameter values. Techniques are presented, based on the comparison of the predictions with test values, for estimating SEA accuracy as a function of frequency for a general structure.

  20. Flight Dynamics Analysis Branch 2005 Technical Highlights

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This report summarizes the major activities and accomplishments carried out by the Flight Dynamics Analysis Branch (FDAB), Code 595, in support of flight projects and technology development initiatives in Fiscal Year (FY) 2005. The report is intended to serve as a summary of the type of support carried out by the FDAB, as well as a concise reference of key accomplishments and mission experience derived from the various mission support roles. The primary focus of the FDAB is to provide expertise in the disciplines of flight dynamics including spacecraft navigation (autonomous and ground based); spacecraft trajectory design and maneuver planning; attitude analysis; attitude determination and sensor calibration; and attitude control subsystem (ACS) analysis and design. The FDAB currently provides support for missions and technology development projects involving NASA, other government agencies, academia, and private industry.

  1. Quasi steady MPD performance analysis

    NASA Astrophysics Data System (ADS)

    Guarducci, F.; Paccani, G.; Lehnert, J.

    2011-04-01

    Pulsed (quasi-steady) solid propellant magnetoplasmadynamic thruster operation has been investigated both in the self-induced and applied magnetic field cases. Input parameters have been varied in order to analyze performance (in particular impulse bit) dependance on these parameters. The stored energy per shot has been set to four values between 2000 and 3000 J, while magnetic field has been set to six values between 0 and 159 mT. Impulse bit has been evaluated through a thrust stand technique: a brief overview of this method is given together with a description of the data processing procedure. Current measurements allow to use Maeker's formula as a reference for comparison between theoretical and empirical results as well as between self and applied field operation. Appreciable improvements of the thruster impulse bit performance have been noticed for defined sets of stored energy and applied field values. An inductive interaction between the magnet coil and the laboratory facilities, resulting in thrust stand displacement, has been observed: this phenomenon and its consequences on measurements have been investigated. A target used as a ballistic pendulum, insensitive to magnetic coupling, has been employed to acquire a new set of measurements: the results obtained with the target technique show a maximum discrepancy of 5% when compared with the measurements derived from the thrust stand technique. Finally, the thrust stand measurements appear to be affected by the inductive interactions only for very high values of the applied field.

  2. Dynamic analysis: a new point of view

    NASA Astrophysics Data System (ADS)

    Chaves, Eduardo W. V.

    2016-05-01

    In this article, an alternative to the classical dynamic equation formulation is presented. To achieve this goal, we need to derive the reciprocal theorem in rates and the principle of virtual work in rates, in a small deformation regime, with which we will be able to obtain an expression for damping force. In this new formulation, some terms that are not commonly considered in the classical formulation appear, e.g., the term that is function of jerk (the rate of change of acceleration). Moreover, in this formulation the term that characterizes material nonlinearity, in dynamic analysis, appears naturally.

  3. Modeling and dynamic performance evaluation of target capture in robotic systems

    SciTech Connect

    Koevecses, J.; Cleghorn, W.L.; Fenton, R.G.

    2000-04-01

    In this paper, a dynamic system consisting of a robot manipulator and a target is analyzed. The target is considered in a general way as a dynamic subsystem having finite mass and moments of inertia (e.g., a rigid body or a second robot). The situation investigated is when the robot establishes interaction with the target in such a way that it intercepts and captures a reference element of the target. The analysis of target capture is divided into three phases in terms of time: the precapture, free motion (finite motion); the transition from free to constrained motion in the vicinity of interception and capture (impulsive motion); and the postcapture, constrained motion (finite motion). The greatest attention is paid to the analysis of the phase of transition, the impulsive motion, and dynamics of the system. Based on the use of impulsive constraints and the Jourdainian formulation of analytical dynamics, a novel approach is proposed for the dynamic modeling of target capture by a robot manipulator. The proposed approach is suitable to handle both finite and impulsive motions in a common analytical framework. Based on the dynamic model developed and using a geometric representation of the system's dynamics, a detailed analysis and a performance evaluation framework are presented for the phase of transition. Both rigid and structurally flexible models of robots are considered. For the performance evaluation analyses, two main concepts are proposed and corresponding performance measures are derived. These tools may be used in the analysis, design, and control of time-varying robotic systems. The dynamic system of a three-link robot arm capturing a rigid body is used to illustrate the material presented.

  4. Dynamic analysis of spur gears using computer program DANST

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Lin, Hsiang Hsi; Liou, Chuen-Huei; Valco, Mark J.

    1993-01-01

    DANST is a computer program for static and dynamic analysis of spur gear systems. The program can be used for parametric studies to predict the effect on dynamic load and tooth bending stress of spur gears due to operating speed, torque, stiffness, damping, inertia, and tooth profile. DANST performs geometric modeling and dynamic analysis for low- or high-contact-ratio spur gears. DANST can simulate gear systems with contact ratio ranging from one to three. It was designed to be easy to use, and it is extensively documented by comments in the source code. This report describes the installation and use of DANST. It covers input data requirements and presents examples. The report also compares DANST predictions for gear tooth loads and bending stress to experimental and finite element results.

  5. Thermal evaluation of advanced solar dynamic heat receiver performance

    NASA Technical Reports Server (NTRS)

    Crane, Roger A.

    1989-01-01

    The thermal performance of a variety of concepts for thermal energy storage as applied to solar dynamic applications is discussed. It is recognized that designs providing large thermal gradients or large temperature swings during orbit are susceptible to early mechanical failure. Concepts incorporating heat pipe technology may encounter operational limitations over sufficiently large ranges. By reviewing the thermal performance of basic designs, the relative merits of the basic concepts are compared. In addition the effect of thermal enhancement and metal utilization as applied to each design provides a partial characterization of the performance improvements to be achieved by developing these technologies.

  6. Laboratory performance of a dynamic ice storage system

    SciTech Connect

    Stovall, T.K.; Tomlinson, J.J.

    1991-06-01

    The performance of a commercial 30-ton dynamic ice storage system was measured in a dedicated laboratory test facility and the results analyzed. The ice storage system was tested over a wide range of operating conditions to characterize the ice generating performance as a function of condensing conditions, ice build time, and defrost time. The overall efficiency of ice production was determined and the effect of refrigeration system component performance on the overall system efficiency was evaluated. The ability of the charged system -- a tank of ice slush -- to meet a simulated cooling load over was also evaluated. 18 refs., 9 figs.

  7. Flight Dynamics Analysis Branch End of Fiscal Year 1999 Report

    NASA Technical Reports Server (NTRS)

    Stengle, Thomas; Flores-Amaya, Felipe

    1999-01-01

    This document summarizes the major activities and accomplishments carried out by the Goddard Space Flight Center (GSFC)'s Flight Dynamics Analysis Branch (FDAB), Code 572, in support of flight projects and technology development initiatives in Fiscal Year (FY) 1999. The document is intended to serve as both an introduction to the type of support carried out by the FDAB (Flight Dynamics Analysis Branch), as well as a concise reference summarizing key analysis results and mission experience derived from the various mission support roles assumed over the past year. The major accomplishments in the FDAB in FY99 were: 1) Provided flight dynamics support to the Lunar Prospector and TRIANA missions among a variety of spacecraft missions; 2) Sponsored the Flight Mechanics Symposium; 3) Supported the Consultative Committee for Space Data Systems (CCSDS) workshops; 4) Performed numerous analyses and studies for future missions; 5) Started the Flight Dynamics Analysis Branch Lab for in-house mission analysis and support; and 6) Complied with all requirements in support of GSFC IS09000 certification.

  8. Dynamic impact analysis of the M1 105mm projectile

    SciTech Connect

    Walls, J.C.; Webb, D.S.

    1993-06-01

    Evaluation of the effects of {open_quotes}rough-handling{close_quotes}-induced stresses in the nose region of a 105mm artillery projectile was performed to determine if these stresses could have contributed to the premature explosion of a projectile during a Desert Shield training mission of the 101st Army Airborne in Saudi Arabia. The rough-handling evaluations were simulated by dynamic impact analysis. It was concluded that the combined residual stress and dynamic impact-induced stress would not be of sufficient magnitude to cause cracking of the projectile in the nose region.

  9. Dynamic impact analysis of the M1 105mm projectile

    SciTech Connect

    Walls, J.C.; Webb, D.S.

    1993-06-01

    Evaluation of the effects of [open quotes]rough-handling[close quotes]-induced stresses in the nose region of a 105mm artillery projectile was performed to determine if these stresses could have contributed to the premature explosion of a projectile during a Desert Shield training mission of the 101st Army Airborne in Saudi Arabia. The rough-handling evaluations were simulated by dynamic impact analysis. It was concluded that the combined residual stress and dynamic impact-induced stress would not be of sufficient magnitude to cause cracking of the projectile in the nose region.

  10. Dynamic analysis using superelements for a large helicopter model

    NASA Technical Reports Server (NTRS)

    Patel, M. P.; Shah, L. C.

    1978-01-01

    Using superelements (substructures), modal and frequency response analysis was performed for a large model of the Advanced Attack Helicopter developed for the U.S. Army. Whiffletree concept was employed so that the residual structure along with the various superelements could be represented as beam-like structures for economical and accurate dynamic analysis. A very large DMAP alter to the rigid format was developed so that the modal analysis, the frequency response, and the strain energy in each component could be computed in the same run.

  11. Cluster analysis of word frequency dynamics

    NASA Astrophysics Data System (ADS)

    Maslennikova, Yu S.; Bochkarev, V. V.; Belashova, I. A.

    2015-01-01

    This paper describes the analysis and modelling of word usage frequency time series. During one of previous studies, an assumption was put forward that all word usage frequencies have uniform dynamics approaching the shape of a Gaussian function. This assumption can be checked using the frequency dictionaries of the Google Books Ngram database. This database includes 5.2 million books published between 1500 and 2008. The corpus contains over 500 billion words in American English, British English, French, German, Spanish, Russian, Hebrew, and Chinese. We clustered time series of word usage frequencies using a Kohonen neural network. The similarity between input vectors was estimated using several algorithms. As a result of the neural network training procedure, more than ten different forms of time series were found. They describe the dynamics of word usage frequencies from birth to death of individual words. Different groups of word forms were found to have different dynamics of word usage frequency variations.

  12. Propellant Slosh Analysis for the Solar Dynamics Observatory

    NASA Technical Reports Server (NTRS)

    Mason, Paul A. C.; Starin, Scott R.

    2005-01-01

    The Solar Dynamics Observatory (SDO) mission, part of the Living With a Star program, is a geosynchronous satellite with tight pointing requirements. Due to a large amount of liquid propellant, a detailed slosh analysis is required to ensure the tight pointing budget can be satisfied. Much of the high fidelity slosh analysis and simulation has been performed via computational fluid dynamics. Even though this method of simulation is very accurate, it requires significant computational effort and specialized knowledge, limiting the ability of the SDO project to access fluid dynamics simulations at will. Furthermore, it is very difficult to incorporate most of these models into simulations of the overall spacecraft and its environment. Ultimately, the effects of the propellant slosh on the attitude stability and pointing performance of the entire spacecraft are of great interest to attitude control engineers. Equivalent mechanical models, such as models that approximate the fluid slosh effects by analogy to the movements of a point-mass pendulum, are important tools in simulating propellant slosh dynamics as part of the entire attitude determination and control system. This paper describes some of the current methods used to analyze and model slosh. It focuses on equivalent mechanical models and their incorporation into control-based analysis tools such as Simulink. The SDO mission is used as the case study for this work.

  13. Dynamical analysis of sea-breeze hodograph rotation in Sardinia

    NASA Astrophysics Data System (ADS)

    Moisseeva, N.; Steyn, D. G.

    2014-09-01

    This study investigates the diurnal evolution of sea-breeze rotation over an island in the mid-latitudes. Earlier research on sea-breezes in Sardinia shows that the onshore winds around various coasts of the island exhibit both the theoretically predicted clockwise rotation as well as seemingly anomalous anti-clockwise rotation. A non-hydrostatic fully compressible numerical model (WRF) is used to simulate wind fields on and around the island on previously-studied sea-breeze days and is shown to accurately capture the circulation on all coasts. Diurnal rotation of wind is examined and patterns of clockwise and anti-clockwise rotation are identified. A dynamical analysis is performed by extracting individual forcing terms from the horizontal momentum equations. Analysis of several regions around the island shows that the direction of rotation is a result of a complex interaction between near-surface and synoptic pressure gradient, Coriolis and advection forcings. An idealized simulation is performed over an artificial island with dramatically simplified topography, yet similar dimensions and latitude to Sardinia. Dynamical analysis of the idealized case reveals a rather different pattern of hodograph rotation to the real Sardinia, yet similar underlying dynamics. The research provides new insights into the dynamics underlying sea-breeze hodograph rotation, especially in coastal zones with complex topography and/or coastline.

  14. Dynamical analysis of sea-breeze hodograph rotation in Sardinia

    NASA Astrophysics Data System (ADS)

    Moisseeva, N.; Steyn, D. G.

    2014-12-01

    This study investigates the diurnal evolution of sea-breeze (SB) rotation over an island at the middle latitudes. Earlier research on sea breezes in Sardinia shows that the onshore winds around various coasts of the island exhibit both the theoretically predicted clockwise rotation as well as seemingly anomalous anticlockwise rotation. A non-hydrostatic fully compressible numerical model (WRF) is used to simulate wind fields on and around the island on previously studied sea-breeze days, and is shown to capture the circulation on all coasts accurately. Diurnal rotation of wind is examined, and patterns of clockwise and anticlockwise rotation are identified. A dynamical analysis is performed by extracting individual forcing terms from the horizontal momentum equations. Analysis of several regions around the island shows that the direction of rotation is a result of a complex interaction between near-surface and synoptic pressure gradient, Coriolis and advection forcings. An idealized simulation is performed over an artificial island with dramatically simplified topography yet similar dimensions and latitude to Sardinia. Dynamical analysis of the idealized case reveals a rather different pattern of hodograph rotation to the real Sardinia, yet similar underlying dynamics. The research provides new insights into the dynamics underlying sea-breeze hodograph rotation, especially in coastal zones with a complex topography and/or coastline.

  15. Dynamic heave-pitch analysis of air cushion landing systems

    NASA Technical Reports Server (NTRS)

    Captain, K. M.; Boghani, A. B.; Wormley, D. N.

    1975-01-01

    A program to develop analytical tools for evaluating the dynamic performance of Air Cushion Landing Systems (ACLS) is described. The heave (vertical) motion of the ACLS was analyzed, and the analysis was extended to cover coupled heave-pitch motions. The mathematical models developed are based on a fundamental analysis of the body dynamics and fluid mechanics of the aircraft-cushion-runway interaction. The air source characteristics, flow losses in the feeding ducts, trunk and cushion, the effects of fluid compressibility, and dynamic trunk deflections, including ground contact are considered. A computer program, based on the heave-pitch analysis, was developed to simulate the dynamic behavior of an ACLS during landing impact and taxi over an irregular runway. The program outputs include ACLS motions, loadings, pressures, and flows as a function of time. To illustrate program use, three basic types of simulations were carried out. The results provide an initial indication of ACLS performance during (1) a static drop, (2) landing impact, and (3) taxi over a runway irregularity.

  16. Precise Analysis of Polymer Rotational Dynamics.

    PubMed

    Kim, Jun Mo; Baig, Chunggi

    2016-01-01

    Through the analysis of individual chain dynamics alongside the corresponding molecular structures under shear via nonequilibrium molecular dynamics simulations of C178H358 linear and short-chain branched polyethylene melts under shear flow, we observed that the conventional method based on the chain end-to-end vector (and/or the gyration tensor of chain) is susceptible to quantitatively inaccurate measurements and often misleading information in describing the rotational dynamics of polymers. Identifying the flaw as attributed to strong irregular Brownian fluctuations inherent to the chain ends associated with their large free volume and strong molecular collisions, we propose a simple, robust way based on the chain center-to-center vector connecting the two centers of mass of the bisected chain, which is shown to adequately describe polymer rotational dynamics without such shortcomings. We present further consideration that the proposed method can be useful in accurately measuring the overall chain structure and dynamics of polymeric materials with various molecular architectures, including branched and ring polymers. PMID:26743689

  17. Niche versus neutrality: a dynamical analysis.

    PubMed

    Kalyuzhny, Michael; Seri, Efrat; Chocron, Rachel; Flather, Curtis H; Kadmon, Ronen; Shnerb, Nadav M

    2014-10-01

    Understanding the forces shaping ecological communities is of crucial importance for basic science and conservation. After 50 years in which ecological theory has focused on either stable communities driven by niche-based forces or nonstable "neutral" communities driven by demographic stochasticity, contemporary theories suggest that ecological communities are driven by the simultaneous effects of both types of mechanisms. Here we examine this paradigm using the longest available records for the dynamics of tropical trees and breeding birds. Applying a macroecological approach and fluctuation analysis techniques borrowed from statistical physics, we show that both stabilizing mechanisms and demographic stochasticity fail to play a dominant role in shaping assemblages over time. Rather, community dynamics in these two very different systems is predominantly driven by environmental stochasticity. Clearly, the current melding of niche and neutral theories cannot account for such dynamics. Our results highlight the need for a new theory of community dynamics integrating environmental stochasticity with weak stabilizing forces and suggest that such theory may better describe the dynamics of ecological communities than current neutral theories, deterministic niche-based theories, or recent hybrids. PMID:25226179

  18. Performance Analysis of Multilevel Parallel Applications on Shared Memory Architectures

    NASA Technical Reports Server (NTRS)

    Jost, Gabriele; Jin, Haoqiang; Labarta, Jesus; Gimenez, Judit; Caubet, Jordi; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    In this paper we describe how to apply powerful performance analysis techniques to understand the behavior of multilevel parallel applications. We use the Paraver/OMPItrace performance analysis system for our study. This system consists of two major components: The OMPItrace dynamic instrumentation mechanism, which allows the tracing of processes and threads and the Paraver graphical user interface for inspection and analyses of the generated traces. We describe how to use the system to conduct a detailed comparative study of a benchmark code implemented in five different programming paradigms applicable for shared memory

  19. Dynamic interactions between hypersonic vehicle aerodynamics and propulsion system performance

    NASA Technical Reports Server (NTRS)

    Flandro, G. A.; Roach, R. L.; Buschek, H.

    1992-01-01

    Described here is the development of a flexible simulation model for scramjet hypersonic propulsion systems. The primary goal is determination of sensitivity of the thrust vector and other system parameters to angle of attack changes of the vehicle. Such information is crucial in design and analysis of control system performance for hypersonic vehicles. The code is also intended to be a key element in carrying out dynamic interaction studies involving the influence of vehicle vibrations on propulsion system/control system coupling and flight stability. Simple models are employed to represent the various processes comprising the propulsion system. A method of characteristics (MOC) approach is used to solve the forebody and external nozzle flow fields. This results in a very fast computational algorithm capable of carrying out the vast number of simulation computations needed in guidance, stability, and control studies. The three-dimensional fore- and aft body (nozzle) geometry is characterized by the centerline profiles as represented by a series of coordinate points and body cross-section curvature. The engine module geometry is represented by an adjustable vertical grid to accommodate variations of the field parameters throughout the inlet and combustor. The scramjet inlet is modeled as a two-dimensional supersonic flow containing adjustable sidewall wedges and multiple fuel injection struts. The inlet geometry including the sidewall wedge angles, the number of injection struts, their sweepback relative to the vehicle reference line, and strut cross-section are user selectable. Combustion is currently represented by a Rayleigh line calculation including corrections for variable gas properties; improved models are being developed for this important element of the propulsion flow field. The program generates (1) variation of thrust magnitude and direction with angle of attack, (2) pitching moment and line of action of the thrust vector, (3) pressure and temperature

  20. Develop feedback system for intelligent dynamic resource allocation to improve application performance.

    SciTech Connect

    Gentile, Ann C.; Brandt, James M.; Tucker, Thomas; Thompson, David

    2011-09-01

    This report provides documentation for the completion of the Sandia Level II milestone 'Develop feedback system for intelligent dynamic resource allocation to improve application performance'. This milestone demonstrates the use of a scalable data collection analysis and feedback system that enables insight into how an application is utilizing the hardware resources of a high performance computing (HPC) platform in a lightweight fashion. Further we demonstrate utilizing the same mechanisms used for transporting data for remote analysis and visualization to provide low latency run-time feedback to applications. The ultimate goal of this body of work is performance optimization in the face of the ever increasing size and complexity of HPC systems.

  1. Dynamical robustness analysis of weighted complex networks

    NASA Astrophysics Data System (ADS)

    He, Zhiwei; Liu, Shuai; Zhan, Meng

    2013-09-01

    Robustness of weighted complex networks is analyzed from nonlinear dynamical point of view and with focus on different roles of high-degree and low-degree nodes. We find that the phenomenon for the low-degree nodes being the key nodes in the heterogeneous networks only appears in weakly weighted networks and for weak coupling. For all other parameters, the heterogeneous networks are always highly vulnerable to the failure of high-degree nodes; this point is the same as in the structural robustness analysis. We also find that with random inactivation, heterogeneous networks are always more robust than the corresponding homogeneous networks with the same average degree except for one special parameter. Thus our findings give an integrated picture for the dynamical robustness analysis on complex networks.

  2. Performance Analysis of GYRO: A Tool Evaluation

    SciTech Connect

    Worley, P.; Roth, P.; Candy, J.; Shan, Hongzhang; Mahinthakumar,G.; Sreepathi, S.; Carrington, L.; Kaiser, T.; Snavely, A.; Reed, D.; Zhang, Y.; Huck, K.; Malony, A.; Shende, S.; Moore, S.; Wolf, F.

    2005-06-26

    The performance of the Eulerian gyrokinetic-Maxwell solver code GYRO is analyzed on five high performance computing systems. First, a manual approach is taken, using custom scripts to analyze the output of embedded wall clock timers, floating point operation counts collected using hardware performance counters, and traces of user and communication events collected using the profiling interface to Message Passing Interface (MPI) libraries. Parts of the analysis are then repeated or extended using a number of sophisticated performance analysis tools: IPM, KOJAK, SvPablo, TAU, and the PMaC modeling tool suite. The paper briefly discusses what has been discovered via this manual analysis process, what performance analyses are inconvenient or infeasible to attempt manually, and to what extent the tools show promise in accelerating or significantly extending the manual performance analyses.

  3. Application of tire dynamics to aircraft landing gear design analysis

    NASA Technical Reports Server (NTRS)

    Black, R. J.

    1983-01-01

    The tire plays a key part in many analyses used for design of aircraft landing gear. Examples include structural design of wheels, landing gear shimmy, brake whirl, chatter and squeal, complex combination of chatter and shimmy on main landing gear (MLG) systems, anti-skid performance, gear walk, and rough terrain loads and performance. Tire parameters needed in the various analyses are discussed. Two tire models are discussed for shimmy analysis, the modified Moreland approach and the von Schlippe-Dietrich approach. It is shown that the Moreland model can be derived from the Von Schlippe-Dietrich model by certain approximations. The remaining analysis areas are discussed in general terms and the tire parameters needed for each are identified. Accurate tire data allows more accurate design analysis and the correct prediction of dynamic performance of aircraft landing gear.

  4. Floating-point performance of ARM cores and their efficiency in classical molecular dynamics

    NASA Astrophysics Data System (ADS)

    Nikolskiy, V.; Stegailov, V.

    2016-02-01

    Supercomputing of the exascale era is going to be inevitably limited by power efficiency. Nowadays different possible variants of CPU architectures are considered. Recently the development of ARM processors has come to the point when their floating point performance can be seriously considered for a range of scientific applications. In this work we present the analysis of the floating point performance of the latest ARM cores and their efficiency for the algorithms of classical molecular dynamics.

  5. Dynamic, stochastic, and topological aspects of polyrhythmic performance.

    PubMed

    Jagacinski, R J; Peper, C E; Beek, P J

    2000-12-01

    Previous research on polyrhythmic performance can be broadly summarized in terms of 2 classes of models: timekeeper models and nonlinear dynamical models. In the former approach, research has been focused on patterns of covariance among time intervals, and in the latter approach, the concentration has been on pattern (in)stability and the spatiotemporal properties of oscillating limbs. It is suggested that one can achieve a more comprehensive theory that incorporates the strengths of each of these approaches by endowing timekeeper models with nonlinear dynamics or by endowing nonlinear oscillator models with stochastic variability. Additionally, those models are complemented by a topological description of performance based on knot theory. Knot theory provides a new index of difficulty for polyrhythmic tapping, a spatial interpretation of transitions between different stable rhythms, and a possible instantiation of N. A. Bernstein's (1967a) notion of a topological motor program. PMID:11114226

  6. Dynamic performance of dissipative dielectric elastomers under alternating mechanical load

    NASA Astrophysics Data System (ADS)

    Zhang, Junshi; Chen, Hualing; Sheng, Junjie; Liu, Lei; Wang, Yongquan; Jia, Shuhai

    2014-07-01

    This paper presents a theoretical study about the effect of dissipation on the dynamic performance of a dielectric elastomer membrane subject to a combination of mechanical load and voltage. The thermodynamic dissipative model is given and the equation of motion is deduced by a free energy method. It is found that when the applied mechanical load and voltage are static, the membrane may reach a state of equilibrium after the viscoelastic relaxation. When the voltage is static but the mechanical load is sinusoidal, the membrane will resonate at multiple frequencies. The study result indicates that the viscoelasticity can reduce the natural frequency and increase the mean stretch of the dielectric elastomer. After the power source is cut off, the effect of current leakage on dynamic performance under alternating mechanical load is that the natural frequency increases and the mean stretch reduces.

  7. An Efficient Crankshaft Dynamic Analysis Using Substructuring with Ritz Vectors

    NASA Astrophysics Data System (ADS)

    MOURELATOS, Z. P.

    2000-11-01

    A structural analysis using dynamic substructuring with Ritz vectors is presented for predicting the dynamic response of an engine crankshaft, based on the finite-element method. A two-level dynamic substructuring is performed using a set of load-dependent Ritz vectors. The rotating crankshaft is properly coupled with the non-rotating, compliant engine block. The block compliance is represented by a distributed linear elastic foundation at each main bearing location. The stiffness of the elastic foundation can be different in the vertical and horizontal planes, thereby considering the anisotropy of the engine block compliance with respect to the crankshaft rotation. The analysis accounts for the kinematic non-linearity resulting from the crankangle-dependent circumferential contact location between each journal and the corresponding bore of the engine block. Crankshaft “bent” and block “misboring” effects due to manufacturing imperfections are considered in the analysis. The superior accuracy and reduced computational effort of the present method as compared with the equivalent superelement analysis in MSC/NASTRAN, are demonstrated using the free and forced vibrations of a slender cylindrical beam and free vibrations of a four-cylinder engine crankshaft. Subsequently, the accuracy of the present method in calculating the dynamic response of engine crankshafts is shown through comparisons between the analytical predictions and experimental results for the torsional vibrations of an in-line five cylinder engine and the bending vibrations of the crankshaft-flywheel assembly of a V6 engine.

  8. Stocker/feeder cattle standardized performance analysis.

    PubMed

    McGrann, J M; McAdams, J

    1995-07-01

    The Standardized Performance Analysis (SPA) for stocker/feed cattle is a recommended set of production and financial performance analysis guidelines developed specifically for the grazing, growing, and finishing phases of beef cattle production. Guidelines were developed by members of the National Cattlemen's Association (NCA), Extension Specialists, and the National Integrated Resource Management Coordination Committee to provide beef cattle producers with a comprehensive, standardized means of measuring, analyzing, and reporting the performance and profitability of an operation. This article describes and illustrates through an example the performance measures chosen. The NCA certifies software and education materials conforming to the Stocker/Feeder Guidelines. PMID:7584818

  9. Improving the performance of molecular dynamics simulations on parallel clusters.

    PubMed

    Borstnik, Urban; Hodoscek, Milan; Janezic, Dusanka

    2004-01-01

    In this article a procedure is derived to obtain a performance gain for molecular dynamics (MD) simulations on existing parallel clusters. Parallel clusters use a wide array of interconnection technologies to connect multiple processors together, often at different speeds, such as multiple processor computers and networking. It is demonstrated how to configure existing programs for MD simulations to efficiently handle collective communication on parallel clusters with processor interconnections of different speeds. PMID:15032512

  10. High-Performance Java Codes for Computational Fluid Dynamics

    NASA Technical Reports Server (NTRS)

    Riley, Christopher; Chatterjee, Siddhartha; Biswas, Rupak; Biegel, Bryan (Technical Monitor)

    2001-01-01

    The computational science community is reluctant to write large-scale computationally -intensive applications in Java due to concerns over Java's poor performance, despite the claimed software engineering advantages of its object-oriented features. Naive Java implementations of numerical algorithms can perform poorly compared to corresponding Fortran or C implementations. To achieve high performance, Java applications must be designed with good performance as a primary goal. This paper presents the object-oriented design and implementation of two real-world applications from the field of Computational Fluid Dynamics (CFD): a finite-volume fluid flow solver (LAURA, from NASA Langley Research Center), and an unstructured mesh adaptation algorithm (2D_TAG, from NASA Ames Research Center). This work builds on our previous experience with the design of high-performance numerical libraries in Java. We examine the performance of the applications using the currently available Java infrastructure and show that the Java version of the flow solver LAURA performs almost within a factor of 2 of the original procedural version. Our Java version of the mesh adaptation algorithm 2D_TAG performs within a factor of 1.5 of its original procedural version on certain platforms. Our results demonstrate that object-oriented software design principles are not necessarily inimical to high performance.

  11. Performance of Smagorinsky and dynamic models in near surface turbulence

    NASA Astrophysics Data System (ADS)

    Brasseur, James G.; Juneja, Anurag

    1997-11-01

    In LES of high-Reynolds-number wall bounded turbulence such as the atmospheric boundary layer (ABL), a viscous sublayer either does not exist or is within the first grid cell, and some integral scale motions are necessarily under-resolved at the first few grid locations. Here the subgrid terms dominate the evolution of resolved velocity and the SGS model performance becomes crucial. To develop improved closures for surface layer turbulence (under-resolved and anisotropic), we explore (a) why current SGS closures fail and (b) what needs to be fixed. We evaluate the performance of the Smagorinsky and dynamic models using DNS data from shear- and buoyancy-driven turbulence as a function of filter cutoff location. We find that the underlying assumption of good alignment between the subgrid stress and resolved strain-rate tensors is not correct in general. More importantly, the Smagorinsky model incorrectly predicts a strong preference in the direction of the SGS stress divergence vector, a spurious prediction that is directly related to the anisotropic structure of the resolved turbulence field. This, and its under-estimation of the SGS pressure gradient, are likely sources of the errors observed in LES of the ABL. Whereas the dynamic formulations do a better job predicting some SGS dynamics, the model fails when the filter cutoff is near an integral scale, and predicts unreasonable fluctuation levels-- although performance is sensitive to type of averaging. *supported by ARO grant DAAL03-92-0117.

  12. Predicting dynamic performance limits for servosystems with saturating nonlinearities

    NASA Technical Reports Server (NTRS)

    Webb, J. A., Jr.; Blech, R. A.

    1979-01-01

    A generalized treatment for a system with a single saturating nonlinearity is presented and compared with frequency response plots obtained from an analog model of the system. Once the amplitude dynamics are predicted with the limit lines, an iterative technique is employed to determine the system phase response. The saturation limit line technique is used in conjunction with velocity and acceleration limits to predict the performance of an electro-hydraulic servosystem containing a single-stage servovalve. Good agreement was obtained between predicted performance and experimental data.

  13. Performance Study and Dynamic Optimization Design for Thread Pool Systems

    SciTech Connect

    Dongping Xu

    2004-12-19

    Thread pools have been widely used by many multithreaded applications. However, the determination of the pool size according to the application behavior still remains problematic. To automate this process, in this thesis we have developed a set of performance metrics for quantitatively analyzing thread pool performance. For our experiments, we built a thread pool system which provides a general framework for thread pool research. Based on this simulation environment, we studied the performance impact brought by the thread pool on different multithreaded applications. Additionally, the correlations between internal characterizations of thread pools and their throughput were also examined. We then proposed and evaluated a heuristic algorithm to dynamically determine the optimal thread pool size. The simulation results show that this approach is effective in improving overall application performance.

  14. Building America Performance Analysis Procedures: Revision 1

    SciTech Connect

    2004-06-01

    To measure progress toward multi-year research goals, cost and performance trade-offs are evaluated through a series of controlled field and laboratory experiments supported by energy analysis techniques using test data to calibrate simulation models.

  15. A Perspective on DSN System Performance Analysis

    NASA Technical Reports Server (NTRS)

    Pham, Timothy T.

    2006-01-01

    This paper discusses the performance analysis effort being carried out in the NASA Deep Space Network. The activity involves root cause analysis of failures and assessment of key performance metrics. The root cause analysis helps pinpoint the true cause of observed problems so that proper correction can be effected. The assessment currently focuses on three aspects: (1) data delivery metrics such as Quantity, Quality, Continuity, and Latency; (2) link-performance metrics such as antenna pointing, system noise temperature, Doppler noise, frequency and time synchronization, wide-area-network loading, link-configuration setup time; and (3) reliability, maintainability, availability metrics. The analysis establishes whether the current system is meeting its specifications and if so, how much margin is available. The findings help identify the weak points in the system and direct attention of programmatic investment for performance improvement.

  16. Vehicle dynamic analysis using neuronal network algorithms

    NASA Astrophysics Data System (ADS)

    Oloeriu, Florin; Mocian, Oana

    2014-06-01

    Theoretical developments of certain engineering areas, the emergence of new investigation tools, which are better and more precise and their implementation on-board the everyday vehicles, all these represent main influence factors that impact the theoretical and experimental study of vehicle's dynamic behavior. Once the implementation of these new technologies onto the vehicle's construction had been achieved, it had led to more and more complex systems. Some of the most important, such as the electronic control of engine, transmission, suspension, steering, braking and traction had a positive impact onto the vehicle's dynamic behavior. The existence of CPU on-board vehicles allows data acquisition and storage and it leads to a more accurate and better experimental and theoretical study of vehicle dynamics. It uses the information offered directly by the already on-board built-in elements of electronic control systems. The technical literature that studies vehicle dynamics is entirely focused onto parametric analysis. This kind of approach adopts two simplifying assumptions. Functional parameters obey certain distribution laws, which are known in classical statistics theory. The second assumption states that the mathematical models are previously known and have coefficients that are not time-dependent. Both the mentioned assumptions are not confirmed in real situations: the functional parameters do not follow any known statistical repartition laws and the mathematical laws aren't previously known and contain families of parameters and are mostly time-dependent. The purpose of the paper is to present a more accurate analysis methodology that can be applied when studying vehicle's dynamic behavior. A method that provides the setting of non-parametrical mathematical models for vehicle's dynamic behavior is relying on neuronal networks. This method contains coefficients that are time-dependent. Neuronal networks are mostly used in various types' system controls, thus

  17. Paramedir: A Tool for Programmable Performance Analysis

    NASA Technical Reports Server (NTRS)

    Jost, Gabriele; Labarta, Jesus; Gimenez, Judit

    2004-01-01

    Performance analysis of parallel scientific applications is time consuming and requires great expertise in areas such as programming paradigms, system software, and computer hardware architectures. In this paper we describe a tool that facilitates the programmability of performance metric calculations thereby allowing the automation of the analysis and reducing the application development time. We demonstrate how the system can be used to capture knowledge and intuition acquired by advanced parallel programmers in order to be transferred to novice users.

  18. Expansion of epicyclic gear dynamic analysis program

    NASA Technical Reports Server (NTRS)

    Boyd, Linda Smith; Pike, James A.

    1987-01-01

    The multiple mesh/single stage dynamics program is a gear tooth analysis program which determines detailed geometry, dynamic loads, stresses, and surface damage factors. The program can analyze a variety of both epicyclic and single mesh systems with spur or helical gear teeth including internal, external, and buttress tooth forms. The modifications refine the options for the flexible carrier and flexible ring gear rim and adds three options: a floating Sun gear option; a natural frequency option; and a finite element compliance formulation for helical gear teeth. The option for a floating Sun incorporates two additional degrees of freedom at the Sun center. The natural frequency option evaluates the frequencies of planetary, star, or differential systems as well as the effect of additional springs at the Sun center and those due to a flexible carrier and/or ring gear rim. The helical tooth pair finite element calculated compliance is obtained from an automated element breakup of the helical teeth and then is used with the basic gear dynamic solution and stress postprocessing routines. The flexible carrier or ring gear rim option for planetary and star spur gear systems allows the output torque per carrier and ring gear rim segment to vary based on the dynamic response of the entire system, while the total output torque remains constant.

  19. Dynamic feature analysis in bidirectional pedestrian flows

    NASA Astrophysics Data System (ADS)

    Xiao-Xia, Yang; Winnie, Daamen; Serge, Paul Hoogendoorn; Hai-Rong, Dong; Xiu-Ming, Yao

    2016-02-01

    Analysis of dynamic features of pedestrian flows is one of the most exciting topics in pedestrian dynamics. This paper focuses on the effect of homogeneity and heterogeneity in three parameters of the social force model, namely desired velocity, reaction time, and body size, on the moving dynamics of bidirectional pedestrian flows in the corridors. The speed and its deviation in free flows are investigated. Simulation results show that the homogeneous higher desired speed which is less than a critical threshold, shorter reaction time or smaller body size results in higher speed of flows. The free dynamics is more sensitive to the heterogeneity in desired speed than that in reaction time or in body size. In particular, an inner lane formation is observed in normal lanes. Furthermore, the breakdown probability and the start time of breakdown are focused on. This study reveals that the sizes of homogeneous desired speed, reaction time or body size play more important roles in affecting the breakdown than the heterogeneities in these three parameters do. Project supported jointly by the National Natural Science Foundation of China (Grant No. 61233001) and the Fundamental Research Funds for Central Universities of China (Grant No. 2013JBZ007).

  20. A Performance Approach to Job Analysis.

    ERIC Educational Resources Information Center

    Folsom, Al

    2001-01-01

    Discussion of performance technology and training evaluation focuses on a job analysis process in the Coast Guard. Topics include problems with low survey response rates; costs; the need for appropriate software; discussions with stakeholders and subject matter experts; and maximizing worthy performance. (LRW)

  1. Teaching performance management using behavior analysis

    PubMed Central

    Ackley, George B. E.; Bailey, Jon S.

    1995-01-01

    A special undergraduate track in performance management, taught using behavior analysis principles, is described. The key elements of the program are presented, including the point systems and other reinforcement contingencies in the classes, the goals of the instructional activities, and many of the requirements used to evaluate student performance. Finally, the article provides examples of the performance management projects students have conducted with local businesses. PMID:22478206

  2. Computational Fluid Dynamics Analysis of Thoracic Aortic Dissection

    NASA Astrophysics Data System (ADS)

    Tang, Yik; Fan, Yi; Cheng, Stephen; Chow, Kwok

    2011-11-01

    Thoracic Aortic Dissection (TAD) is a cardiovascular disease with high mortality. An aortic dissection is formed when blood infiltrates the layers of the vascular wall, and a new artificial channel, the false lumen, is created. The expansion of the blood vessel due to the weakened wall enhances the risk of rupture. Computational fluid dynamics analysis is performed to study the hemodynamics of this pathological condition. Both idealized geometry and realistic patient configurations from computed tomography (CT) images are investigated. Physiological boundary conditions from in vivo measurements are employed. Flow configuration and biomechanical forces are studied. Quantitative analysis allows clinicians to assess the risk of rupture in making decision regarding surgical intervention.

  3. DEAN: A program for dynamic engine analysis

    NASA Technical Reports Server (NTRS)

    Sadler, G. G.; Melcher, K. J.

    1985-01-01

    The Dynamic Engine Analysis program, DEAN, is a FORTRAN code implemented on the IBM/370 mainframe at NASA Lewis Research Center for digital simulation of turbofan engine dynamics. DEAN is an interactive program which allows the user to simulate engine subsystems as well as a full engine systems with relative ease. The nonlinear first order ordinary differential equations which define the engine model may be solved by one of four integration schemes, a second order Runge-Kutta, a fourth order Runge-Kutta, an Adams Predictor-Corrector, or Gear's method for still systems. The numerical data generated by the model equations are displayed at specified intervals between which the user may choose to modify various parameters affecting the model equations and transient execution. Following the transient run, versatile graphics capabilities allow close examination of the data. DEAN's modeling procedure and capabilities are demonstrated by generating a model of simple compressor rig.

  4. Multicomponent dynamical nucleation theory and sensitivity analysis.

    PubMed

    Kathmann, Shawn M; Schenter, Gregory K; Garrett, Bruce C

    2004-05-15

    Vapor to liquid multicomponent nucleation is a dynamical process governed by a delicate interplay between condensation and evaporation. Since the population of the vapor phase is dominated by monomers at reasonable supersaturations, the formation of clusters is governed by monomer association and dissociation reactions. Although there is no intrinsic barrier in the interaction potential along the minimum energy path for the association process, the formation of a cluster is impeded by a free energy barrier. Dynamical nucleation theory provides a framework in which equilibrium evaporation rate constants can be calculated and the corresponding condensation rate constants determined from detailed balance. The nucleation rate can then be obtained by solving the kinetic equations. The rate constants governing the multistep kinetics of multicomponent nucleation including sensitivity analysis and the potential influence of contaminants will be presented and discussed. PMID:15267849

  5. Velocity fluctuation analysis via dynamic programming

    SciTech Connect

    Schlossberg, D. J.; Gupta, D. K.; Fonck, R. J.; McKee, G. R.; Shafer, M. W.

    2006-10-15

    A new method of calculating one-dimensional velocity fluctuations from spatially resolved density fluctuation measurements is presented. The algorithm uses vector-matching methods of dynamic programming that match structures, such as turbulent fluctuations, in two data sets. The associated time delay between data sets is estimated by determining an optimal path to transform one vector to another. This time-delay-estimation (TDE) method establishes a new benchmark for velocity analysis by achieving higher sensitivity and frequency response than previously developed methods, such as time-resolved cross correlations and wavelets. TDE has been successfully applied to beam emission spectroscopy measurements of density fluctuations to obtain poloidal flow fluctuations associated with such phenomena as the geodesic acoustic mode. The dynamic programming algorithm should allow extension to high frequency velocity fluctuations associated with underlying electrostatic potential and resulting ExB fluctuations.

  6. Parellel beam dynamics calculations on high performance computers

    SciTech Connect

    Ryne, R.; Habib, S.

    1996-12-01

    Faced with a backlog of nuclear waste and weapons plutonium, as well as an ever-increasing public concern about safety and environmental issues associated with conventional nuclear reactors, many countries are studying new, accelerator-driven technologies that hold the promise of providing safe and effective solutions to these problems. Proposed projects include accelerator transmutation of waste (ATW), accelerator-based conversion of plutonium (ABC), accelerator-driven energy production (ADEP), and accelerator production of tritium (APT). Also, next-generation spallation neutron sources based on similar technology will play a major role in materials science and biological science research. The design of accelerators for these projects will require a major advance in numerical modeling capability. For example, beam dynamics simulations with approximately 100 million particles will be needed to ensure that extremely stringent beam loss requirements (less than a nanoampere per meter) can be met. Compared with typical present-day modeling using 10,000-100,000 particles, this represents an increase of 3-4 orders of magnitude. High performance computing (HPC) platforms make it possible to perform such large scale simulations, which require 10`s of GBytes of memory. They also make it possible to perform smaller simulations in a matter of hours that would require months to run on a single processor workstation. This paper will describe how HPC platforms can be used to perform the numerically intensive beam dynamics simulations required for development of these new accelerator-driven technologies.

  7. Parallel beam dynamics calculations on high performance computers

    NASA Astrophysics Data System (ADS)

    Ryne, Robert; Habib, Salman

    1997-02-01

    Faced with a backlog of nuclear waste and weapons plutonium, as well as an ever-increasing public concern about safety and environmental issues associated with conventional nuclear reactors, many countries are studying new, accelerator-driven technologies that hold the promise of providing safe and effective solutions to these problems. Proposed projects include accelerator transmutation of waste (ATW), accelerator-based conversion of plutonium (ABC), accelerator-driven energy production (ADEP), and accelerator production of tritium (APT). Also, next-generation spallation neutron sources based on similar technology will play a major role in materials science and biological science research. The design of accelerators for these projects will require a major advance in numerical modeling capability. For example, beam dynamics simulations with approximately 100 million particles will be needed to ensure that extremely stringent beam loss requirements (less than a nanoampere per meter) can be met. Compared with typical present-day modeling using 10,000-100,000 particles, this represents an increase of 3-4 orders of magnitude. High performance computing (HPC) platforms make it possible to perform such large scale simulations, which require 10's of GBytes of memory. They also make it possible to perform smaller simulations in a matter of hours that would require months to run on a single processor workstation. This paper will describe how HPC platforms can be used to perform the numerically intensive beam dynamics simulations required for development of these new accelerator-driven technologies.

  8. Performance optimisations for distributed analysis in ALICE

    NASA Astrophysics Data System (ADS)

    Betev, L.; Gheata, A.; Gheata, M.; Grigoras, C.; Hristov, P.

    2014-06-01

    Performance is a critical issue in a production system accommodating hundreds of analysis users. Compared to a local session, distributed analysis is exposed to services and network latencies, remote data access and heterogeneous computing infrastructure, creating a more complex performance and efficiency optimization matrix. During the last 2 years, ALICE analysis shifted from a fast development phase to the more mature and stable code. At the same time, the frameworks and tools for deployment, monitoring and management of large productions have evolved considerably too. The ALICE Grid production system is currently used by a fair share of organized and individual user analysis, consuming up to 30% or the available resources and ranging from fully I/O-bound analysis code to CPU intensive correlations or resonances studies. While the intrinsic analysis performance is unlikely to improve by a large factor during the LHC long shutdown (LS1), the overall efficiency of the system has still to be improved by an important factor to satisfy the analysis needs. We have instrumented all analysis jobs with "sensors" collecting comprehensive monitoring information on the job running conditions and performance in order to identify bottlenecks in the data processing flow. This data are collected by the MonALISa-based ALICE Grid monitoring system and are used to steer and improve the job submission and management policy, to identify operational problems in real time and to perform automatic corrective actions. In parallel with an upgrade of our production system we are aiming for low level improvements related to data format, data management and merging of results to allow for a better performing ALICE analysis.

  9. A nonlinear model for top fuel dragster dynamic performance assessment

    NASA Astrophysics Data System (ADS)

    Spanos, P. D.; Castillo, D. H.; Kougioumtzoglou, I. A.; Tapia, R. A.

    2012-02-01

    The top fuel dragster is the fastest and quickest vehicle in drag racing. This vehicle is capable of travelling a quarter mile in less than 4.5 s, reaching a final speed in excess of 330 miles per hour. The average power delivered by its engine exceeds 7000 Hp. To analyse and eventually increase the performance of a top fuel dragster, a dynamic model of the vehicle is developed. Longitudinal, vertical, and pitching chassis motions are considered, as well as drive-train dynamics. The aerodynamics of the vehicle, the engine characteristics, and the force due to the combustion gases are incorporated into the model. Further, a simplified model of the traction characteristics of the rear tyres is developed where the traction is calculated as a function of the slip ratio and the velocity. The resulting nonlinear, coupled differential equations of motion are solved using a fourth-order Runge-Kutta numerical integration scheme. Several simulation runs are made to investigate the effects of the aerodynamics and of the engine's initial torque in the performance of the vehicle. The results of the computational simulations are scrutinised by comparisons with data from actual dragster races. Ultimately, the proposed dynamic model of the dragster can be used to improve the aerodynamics, the engine and clutch set-ups of the vehicle, and possibly facilitate the redesign of the dragster.

  10. Flexible body dynamic stability for high performance aircraft

    NASA Technical Reports Server (NTRS)

    Goforth, E. A.; Youssef, H. M.; Apelian, C. V.; Schroeder, S. C.

    1991-01-01

    Dynamic equations which include the effects of unsteady aerodynamic forces and a flexible body structure were developed for a free flying high performance fighter aircraft. The linear and angular deformations are assumed to be small in the body reference frame, allowing the equations to be linearized in the deformation variables. Equations for total body dynamics and flexible body dynamics are formulated using the hybrid coordinate method and integrated in a state space format. A detailed finite element model of a generic high performance fighter aircraft is used to generate the mass and stiffness matrices. Unsteady aerodynamics are represented by a rational function approximation of the doublet lattice matrices. The equations simplify for the case of constant angular rate of the body reference frame, allowing the effect of roll rate to be studied by computing the eigenvalues of the system. It is found that the rigid body modes of the aircraft are greatly affected by introducing a constant roll rate, while the effect on the flexible modes is minimal for this configuration.

  11. Interfacing Computer Aided Parallelization and Performance Analysis

    NASA Technical Reports Server (NTRS)

    Jost, Gabriele; Jin, Haoqiang; Labarta, Jesus; Gimenez, Judit; Biegel, Bryan A. (Technical Monitor)

    2003-01-01

    When porting sequential applications to parallel computer architectures, the program developer will typically go through several cycles of source code optimization and performance analysis. We have started a project to develop an environment where the user can jointly navigate through program structure and performance data information in order to make efficient optimization decisions. In a prototype implementation we have interfaced the CAPO computer aided parallelization tool with the Paraver performance analysis tool. We describe both tools and their interface and give an example for how the interface helps within the program development cycle of a benchmark code.

  12. Dispersion analysis and linear error analysis capabilities of the space vehicle dynamics simulation program

    NASA Technical Reports Server (NTRS)

    Snow, L. S.; Kuhn, A. E.

    1975-01-01

    Previous error analyses conducted by the Guidance and Dynamics Branch of NASA have used the Guidance Analysis Program (GAP) as the trajectory simulation tool. Plans are made to conduct all future error analyses using the Space Vehicle Dynamics Simulation (SVDS) program. A study was conducted to compare the inertial measurement unit (IMU) error simulations of the two programs. Results of the GAP/SVDS comparison are presented and problem areas encountered while attempting to simulate IMU errors, vehicle performance uncertainties and environmental uncertainties using SVDS are defined. An evaluation of the SVDS linear error analysis capability is also included.

  13. Investigation of Control Inceptor Dynamics and Effect on Human Subject Performance

    NASA Technical Reports Server (NTRS)

    Stanco, Anthony A.; Cardullo, Frank M.; Houck, Jacob A.; Grube, Richard C.; Kelly, Lon C.

    2013-01-01

    The control inceptor used in a vehicle simulation is an important part of adequately representing the dynamics of the vehicle. The inceptor characteristics are typically based on a second order spring mass damper system with damping, force gradient, breakout force, and natural frequency parameters. Changing these parameters can have a great effect on pilot control of the vehicle. A quasi transfer of training experiment was performed employing a high fidelity and a low fidelity control inceptor. A disturbance compensatory task was employed which involved a simple horizon line disturbed in roll by a sum of sinusoids presented in an out-the-window display. Vehicle dynamics were modeled as 1/s and 1/s2. The task was to maintain level flight. Twenty subjects were divided between the high and the low fidelity training groups. Each group was trained to a performance asymptote, and then transferred to the high fidelity simulation. RMS tracking error, a PSD analysis, and a workload analysis were performed to quantify the transfer of training effect. Quantitative results of the experiments show that there is no significant difference between the high and low fidelity training groups for 1/s plant dynamics. For 1/s2 plant dynamics there is a greater difference in tracking performance and PSD; and the subjects are less correlated with the input disturbance function

  14. Improving Dynamic Load and Generator Response PerformanceTools

    SciTech Connect

    Lesieutre, Bernard C.

    2005-11-01

    This report is a scoping study to examine research opportunities to improve the accuracy of the system dynamic load and generator models, data and performance assessment tools used by CAISO operations engineers and planning engineers, as well as those used by their counterparts at the California utilities, to establish safe operating margins. Model-based simulations are commonly used to assess the impact of credible contingencies in order to determine system operating limits (path ratings, etc.) to ensure compliance with NERC and WECC reliability requirements. Improved models and a better understanding of the impact of uncertainties in these models will increase the reliability of grid operations by allowing operators to more accurately study system voltage problems and the dynamic stability response of the system to disturbances.

  15. Performance tradeoffs in static and dynamic load balancing strategies

    NASA Technical Reports Server (NTRS)

    Iqbal, M. A.; Saltz, J. H.; Bokhart, S. H.

    1986-01-01

    The problem of uniformly distributing the load of a parallel program over a multiprocessor system was considered. A program was analyzed whose structure permits the computation of the optimal static solution. Then four strategies for load balancing were described and their performance compared. The strategies are: (1) the optimal static assignment algorithm which is guaranteed to yield the best static solution, (2) the static binary dissection method which is very fast but sub-optimal, (3) the greedy algorithm, a static fully polynomial time approximation scheme, which estimates the optimal solution to arbitrary accuracy, and (4) the predictive dynamic load balancing heuristic which uses information on the precedence relationships within the program and outperforms any of the static methods. It is also shown that the overhead incurred by the dynamic heuristic is reduced considerably if it is started off with a static assignment provided by either of the other three strategies.

  16. Dynamic Performance of Subway Vehicle with Linear Induction Motor System

    NASA Astrophysics Data System (ADS)

    Wu, Pingbo; Luo, Ren; Hu, Yan; Zeng, Jing

    The light rail vehicle with Linear Induction Motor (LIM) bogie, which is a new type of urban rail traffic tool, has the advantages of low costs, wide applicability, low noise, simple maintenance and better dynamic behavior. This kind of vehicle, supported and guided by the wheel and rail, is not driven by the wheel/rail adhesion force, but driven by the electromagnetic force between LIM and reaction plate. In this paper, three different types of suspensions and their characteristic are discussed with considering the interactions both between wheel and rail and between LIM and reaction plate. A nonlinear mathematical model of the vehicle with LIM bogie is set up by using the software SIMPACK, and the electromechanical model is also set up on Simulink roof. Then the running behavior of the LIM vehicle is simulated, and the influence of suspension on the vehicle dynamic performance is investigated.

  17. Software life cycle dynamic simulation model: The organizational performance submodel

    NASA Technical Reports Server (NTRS)

    Tausworthe, Robert C.

    1985-01-01

    The submodel structure of a software life cycle dynamic simulation model is described. The software process is divided into seven phases, each with product, staff, and funding flows. The model is subdivided into an organizational response submodel, a management submodel, a management influence interface, and a model analyst interface. The concentration here is on the organizational response model, which simulates the performance characteristics of a software development subject to external and internal influences. These influences emanate from two sources: the model analyst interface, which configures the model to simulate the response of an implementing organization subject to its own internal influences, and the management submodel that exerts external dynamic control over the production process. A complete characterization is given of the organizational response submodel in the form of parameterized differential equations governing product, staffing, and funding levels. The parameter values and functions are allocated to the two interfaces.

  18. Laser speckle analysis of retinal vascular dynamics

    PubMed Central

    Neganova, Anastasiia Y; Postnov, Dmitry D; Jacobsen, Jens Christian B.; Sosnovtseva, Olga

    2016-01-01

    Studies of vascular responses are usually performed on isolated vessels or on single vessels in vivo. This allows for precise measurements of diameter or blood flow. However, dynamical responses of the whole microvascular network are difficult to access experimentally. We suggest to use full-field laser speckle imaging to evaluate vascular responses of the retinal network. Image segmentation and vessel recognition algorithms together with response mapping allow us to analyze diameter changes and blood flow responses in the intact retinal network upon systemic administration of the vasoconstrictor angiotensin II, the vasodilator acetylcholine or on the changing level of anesthesia in in vivo rat preparations.

  19. Employment of CB models for non-linear dynamic analysis

    NASA Technical Reports Server (NTRS)

    Klein, M. R. M.; Deloo, P.; Fournier-Sicre, A.

    1990-01-01

    The non-linear dynamic analysis of large structures is always very time, effort and CPU consuming. Whenever possible the reduction of the size of the mathematical model involved is of main importance to speed up the computational procedures. Such reduction can be performed for the part of the structure which perform linearly. Most of the time, the classical Guyan reduction process is used. For non-linear dynamic process where the non-linearity is present at interfaces between different structures, Craig-Bampton models can provide a very rich information, and allow easy selection of the relevant modes with respect to the phenomenon driving the non-linearity. The paper presents the employment of Craig-Bampton models combined with Newmark direct integration for solving non-linear friction problems appearing at the interface between the Hubble Space Telescope and its solar arrays during in-orbit maneuvers. Theory, implementation in the FEM code ASKA, and practical results are shown.

  20. DYNAMIC NON LINEAR IMPACT ANALYSIS OF FUEL CASK CONTAINMENT VESSELS

    SciTech Connect

    Leduc, D

    2008-06-10

    Large fuel casks present challenges when evaluating their performance in the accident sequence specified in 10CFR 71. Testing is often limited because of cost, difficulty in preparing test units and the limited availability of facilities which can carry out such tests. In the past, many casks were evaluated without testing using simplified analytical methods. This paper details the use of dynamic non-linear analysis of large fuel casks using advanced computational techniques. Results from the dynamic analysis of two casks, the T-3 Spent Fuel Cask and the Hanford Un-irradiated Fuel Package are examined in detail. These analyses are used to fully evaluate containment vessel stresses and strains resulting from complex loads experienced by cask components during impacts. Importantly, these advanced analytical analyses are capable of examining stresses in key regions of the cask including the cask closure. This paper compares these advanced analytical results with the results of simplified cask analyses like those detailed in NUREG 3966.

  1. RAVEN, a New Software for Dynamic Risk Analysis

    SciTech Connect

    Cristian Rabiti; Andrea Alfonsi; Joshua Cogliati; Diego Mandelli; Robert Kinoshita

    2014-06-01

    RAVEN is a generic software driver to perform parametric and probabilistic analysis of code simulating complex systems. Initially developed to provide dynamic risk analysis capabilities to the RELAP-7 code [1] is currently being generalized with the addition of Application Programming Interfaces (APIs). These interfaces are used to extend RAVEN capabilities to any software as long as all the parameters that need to be perturbed are accessible by inputs files or directly via python interfaces. RAVEN is capable to investigate the system response probing the input space using Monte Carlo, grid strategies, or Latin Hyper Cube schemes, but its strength is its focus toward system feature discovery like limit surfaces separating regions of the input space leading to system failure using dynamic supervised learning techniques. The paper will present an overview of the software capabilities and their implementation schemes followed by same application examples.

  2. Comparative performance analysis of mobile displays

    NASA Astrophysics Data System (ADS)

    Safaee-Rad, Reza; Aleksic, Milivoje

    2012-01-01

    Cell-phone display performance (in terms of color quality and optical efficiency) has become a critical factor in creating a positive user experience. As a result, there is a significant amount of effort by cell-phone OEMs to provide a more competitive display solution. This effort is focused on using different display technologies (with significantly different color characteristics) and more sophisticated display processors. In this paper, the results of a mobile-display comparative performance analysis are presented. Three cell-phones from major OEMs are selected and their display performances are measured and quantified. Comparative performance analysis is done using display characteristics such as display color gamut size, RGB-channels crosstalk, RGB tone responses, gray tracking performance, color accuracy, and optical efficiency.

  3. Integrating Reliability Analysis with a Performance Tool

    NASA Technical Reports Server (NTRS)

    Nicol, David M.; Palumbo, Daniel L.; Ulrey, Michael

    1995-01-01

    A large number of commercial simulation tools support performance oriented studies of complex computer and communication systems. Reliability of these systems, when desired, must be obtained by remodeling the system in a different tool. This has obvious drawbacks: (1) substantial extra effort is required to create the reliability model; (2) through modeling error the reliability model may not reflect precisely the same system as the performance model; (3) as the performance model evolves one must continuously reevaluate the validity of assumptions made in that model. In this paper we describe an approach, and a tool that implements this approach, for integrating a reliability analysis engine into a production quality simulation based performance modeling tool, and for modeling within such an integrated tool. The integrated tool allows one to use the same modeling formalisms to conduct both performance and reliability studies. We describe how the reliability analysis engine is integrated into the performance tool, describe the extensions made to the performance tool to support the reliability analysis, and consider the tool's performance.

  4. Comprehensive analysis of transport aircraft flight performance

    NASA Astrophysics Data System (ADS)

    Filippone, Antonio

    2008-04-01

    This paper reviews the state-of-the art in comprehensive performance codes for fixed-wing aircraft. The importance of system analysis in flight performance is discussed. The paper highlights the role of aerodynamics, propulsion, flight mechanics, aeroacoustics, flight operation, numerical optimisation, stochastic methods and numerical analysis. The latter discipline is used to investigate the sensitivities of the sub-systems to uncertainties in critical state parameters or functional parameters. The paper discusses critically the data used for performance analysis, and the areas where progress is required. Comprehensive analysis codes can be used for mission fuel planning, envelope exploration, competition analysis, a wide variety of environmental studies, marketing analysis, aircraft certification and conceptual aircraft design. A comprehensive program that uses the multi-disciplinary approach for transport aircraft is presented. The model includes a geometry deck, a separate engine input deck with the main parameters, a database of engine performance from an independent simulation, and an operational deck. The comprehensive code has modules for deriving the geometry from bitmap files, an aerodynamics model for all flight conditions, a flight mechanics model for flight envelopes and mission analysis, an aircraft noise model and engine emissions. The model is validated at different levels. Validation of the aerodynamic model is done against the scale models DLR-F4 and F6. A general model analysis and flight envelope exploration are shown for the Boeing B-777-300 with GE-90 turbofan engines with intermediate passenger capacity (394 passengers in 2 classes). Validation of the flight model is done by sensitivity analysis on the wetted area (or profile drag), on the specific air range, the brake-release gross weight and the aircraft noise. A variety of results is shown, including specific air range charts, take-off weight-altitude charts, payload-range performance

  5. Architectural Analysis of Dynamically Reconfigurable Systems

    NASA Technical Reports Server (NTRS)

    Lindvall, Mikael; Godfrey, Sally; Ackermann, Chris; Ray, Arnab; Yonkwa, Lyly

    2010-01-01

    oTpics include: the problem (increased flexibility of architectural styles decrease analyzability, behavior emerges and varies depending on the configuration, does the resulting system run according to the intended design, and architectural decisions can impede or facilitate testing); top down approach to architecture analysis, detection of defects and deviations, and architecture and its testability; currently targeted projects GMSEC and CFS; analyzing software architectures; analyzing runtime events; actual architecture recognition; GMPUB in Dynamic SAVE; sample output from new approach; taking message timing delays into account; CFS examples of architecture and testability; some recommendations for improved testablity; and CFS examples of abstract interfaces and testability; CFS example of opening some internal details.

  6. Performance analysis of LAN bridges and routers

    NASA Technical Reports Server (NTRS)

    Hajare, Ankur R.

    1991-01-01

    Bridges and routers are used to interconnect Local Area Networks (LANs). The performance of these devices is important since they can become bottlenecks in large multi-segment networks. Performance metrics and test methodology for bridges and routers were not standardized. Performance data reported by vendors is not applicable to the actual scenarios encountered in an operational network. However, vendor-provided data can be used to calibrate models of bridges and routers that, along with other models, yield performance data for a network. Several tools are available for modeling bridges and routers - Network II.5 was used. The results of the analysis of some bridges and routers are presented.

  7. Effect of Eccentricity on the Static and Dynamic Performance of a Turbulent Hybrid Bearing

    NASA Technical Reports Server (NTRS)

    Sanandres, Luis A.

    1991-01-01

    The effect of journal eccentricity on the static and dynamic performance of a water lubricated, 5-recess hybrid bearing is presented in detail. The hydrostatic bearing has been designed to operate at a high speed and with a large level of external pressurization. The operating conditions determine the flow in the bearing to be highly turbulent and strongly dominated by fluid inertia effects. The analysis covers the spectrum of journal center displacements directed towards the middle of a recess and towards the mid-land portion between two consecutive recesses. Predicted dynamic force coefficients are uniform for small to moderate eccentricities. For large journal center displacements, fluid cavitation and recess position determine large changes in the bearing dynamic performance. The effect of fluid inertia force coefficients on the threshold speed of instability and whirl ratio of a single mass flexible rotor is discussed.

  8. Dynamical Analysis of the SHIELD Galaxies

    NASA Astrophysics Data System (ADS)

    McNichols, Andrew Thomas; Teich, Yaron G.; Cannon, John M.

    2015-08-01

    We present a dynamical analysis of the 12 extremely low-mass dwarf galaxies that comprise SHIELD, a product of the Arecibo Legacy Fast ALFA survey (ALFALFA). We use multi-configuration, high spatial (˜ 150 - 350 pc) and spectral (0.82 - 2.46 km s-1 ch-1) resolution data obtained from 21 cm observations conducted with the Karl G. Jansky Very Large Array. For each source, we attempt to derive an inclination-corrected rotation curve, to calculate the maximum rotation velocity (≤ 30 km s-1 for the survey population), and to further constrain the H I mass. For sources from which a sufficiently precise rotation curve can be derived, we use spatially resolved Spitzer Space Telescope 3.6 and 4.5 μm images to determine the stellar mass as a function of radius. The gaseous and stellar mass estimates are then used to decompose the total dynamical mass values and to obtain neutral gas fractions and relative baryonic content. Characterizing the kinematics of the SHIELD galaxies allows us to draw more general conclusions about the structure and dynamical evolution of low mass dwarf galaxies in the local universe.This work is a result of collaboration with the SHIELD Team and is supported by NSF grant 1211683.

  9. Perturbation analysis for patch occupancy dynamics

    USGS Publications Warehouse

    Martin, Julien; Nichols, James D.; McIntyre, Carol L.; Ferraz, Goncalo; Hines, James E.

    2009-01-01

    Perturbation analysis is a powerful tool to study population and community dynamics. This article describes expressions for sensitivity metrics reflecting changes in equilibrium occupancy resulting from small changes in the vital rates of patch occupancy dynamics (i.e., probabilities of local patch colonization and extinction). We illustrate our approach with a case study of occupancy dynamics of Golden Eagle (Aquila chrysaetos) nesting territories. Examination of the hypothesis of system equilibrium suggests that the system satisfies equilibrium conditions. Estimates of vital rates obtained using patch occupancy models are used to estimate equilibrium patch occupancy of eagles. We then compute estimates of sensitivity metrics and discuss their implications for eagle population ecology and management. Finally, we discuss the intuition underlying our sensitivity metrics and then provide examples of ecological questions that can be addressed using perturbation analyses. For instance, the sensitivity metrics lead to predictions about the relative importance of local colonization and local extinction probabilities in influencing equilibrium occupancy for rare and common species.

  10. Incorporation of inexact dynamic optimization with fuzzy relation analysis for integrated climate change impact study

    SciTech Connect

    Huang, G.H.; Cohen, S.J.; Yin, Y.Y.; Bass, B. |

    1996-09-01

    A climatic change impact assessment was performed for agricultural and timbering activities. An inexact dynamic optimization model was utilized that can reflect complex system features and a related fuzzy system relation analysis method for comprehensive impact patterns assessment.

  11. Decision Analysis of Dynamic Spectrum Access Rules

    SciTech Connect

    Juan D. Deaton; Luiz A. DaSilva; Christian Wernz

    2011-12-01

    A current trend in spectrum regulation is to incorporate spectrum sharing through the design of spectrum access rules that support Dynamic Spectrum Access (DSA). This paper develops a decision-theoretic framework for regulators to assess the impacts of different decision rules on both primary and secondary operators. We analyze access rules based on sensing and exclusion areas, which in practice can be enforced through geolocation databases. Our results show that receiver-only sensing provides insufficient protection for primary and co-existing secondary users and overall low social welfare. On the other hand, using sensing information between the transmitter and receiver of a communication link, provides dramatic increases in system performance. The performance of using these link end points is relatively close to that of using many cooperative sensing nodes associated to the same access point and large link exclusion areas. These results are useful to regulators and network developers in understanding in developing rules for future DSA regulation.

  12. Spectrum analysis with quantum dynamical systems

    NASA Astrophysics Data System (ADS)

    Ng, Shilin; Ang, Shan Zheng; Wheatley, Trevor A.; Yonezawa, Hidehiro; Furusawa, Akira; Huntington, Elanor H.; Tsang, Mankei

    2016-04-01

    Measuring the power spectral density of a stochastic process, such as a stochastic force or magnetic field, is a fundamental task in many sensing applications. Quantum noise is becoming a major limiting factor to such a task in future technology, especially in optomechanics for temperature, stochastic gravitational wave, and decoherence measurements. Motivated by this concern, here we prove a measurement-independent quantum limit to the accuracy of estimating the spectrum parameters of a classical stochastic process coupled to a quantum dynamical system. We demonstrate our results by analyzing the data from a continuous-optical-phase-estimation experiment and showing that the experimental performance with homodyne detection is close to the quantum limit. We further propose a spectral photon-counting method that can attain quantum-optimal performance for weak modulation and a coherent-state input, with an error scaling superior to that of homodyne detection at low signal-to-noise ratios.

  13. Comparing the Performance of Two Dynamic Load Distribution Methods

    NASA Technical Reports Server (NTRS)

    Kale, L. V.

    1987-01-01

    Parallel processing of symbolic computations on a message-passing multi-processor presents one challenge: To effectively utilize the available processors, the load must be distributed uniformly to all the processors. However, the structure of these computations cannot be predicted in advance. go, static scheduling methods are not applicable. In this paper, we compare the performance of two dynamic, distributed load balancing methods with extensive simulation studies. The two schemes are: the Contracting Within a Neighborhood (CWN) scheme proposed by us, and the Gradient Model proposed by Lin and Keller. We conclude that although simpler, the CWN is significantly more effective at distributing the work than the Gradient model.

  14. Rigorous performance bounds for quadratic and nested dynamical decoupling

    SciTech Connect

    Xia, Yuhou; Uhrig, Goetz S.; Lidar, Daniel A.

    2011-12-15

    We present rigorous performance bounds for the quadratic dynamical decoupling pulse sequence which protects a qubit from general decoherence, and for its nested generalization to an arbitrary number of qubits. Our bounds apply under the assumptions of instantaneous pulses and of bounded perturbing environment and qubit-environment Hamiltonians such as those realized by baths of nuclear spins in quantum dots. We prove that if the total sequence time is fixed then the trace-norm distance between the unperturbed and protected system states can be made arbitrarily small by increasing the number of applied pulses.

  15. Dynamic performance of fossil-fueled power plants

    SciTech Connect

    Armor, A.F.; Bennett, W.E.; Di Domenico, P.N.; Shor, S.W.W.; Smith, L.P.

    1982-10-01

    Dynamic simulation is a valuable tool for optimizing the design and operation of steam electric power plants, especially those that change load or shut down frequently. However, its use has been limited because it has required experienced modeling specialists. An easy-to-use modeling system has therefore been developed under Electric Power Research Institute sponsorship. It has been tested by simulating transients performed on Boston Edison Company's Mystic Unit 7, a 550-MW oil-fired plant, with good agreement between the simulations and the recorded plant transients.

  16. Effect of material uncertainties on dynamic analysis of piezoelectric fans

    NASA Astrophysics Data System (ADS)

    Srivastava, Swapnil; Yadav, Shubham Kumar; Mukherjee, Sujoy

    2015-04-01

    A piezofan is a resonant device that uses a piezoceramic material to induce oscillations in a cantilever beam. In this study, lumped-mass modelling is used to analyze a piezoelectric fan. Uncertainties are associated with the piezoelectric structures due to several reasons such as variation during manufacturing process, temperature, presence of adhesive layer between the piezoelectric actuator/sensor and the shim stock etc. Presence of uncertainty in the piezoelectric materials can influence the dynamic behavior of the piezoelectric fan such as natural frequency, tip deflection etc. Moreover, these quantities will also affect the performance parameters of the piezoelectric fan. Uncertainty analysis is performed using classical Monte Carlo Simulation (MCS). It is found that the propagation of uncertainty causes significant deviations from the baseline deterministic predictions, which also affect the achievable performance of the piezofan. The numerical results in this paper provide useful bounds on several performance parameters of the cooling fan and will enhance confidence in the design process.

  17. Comparative Sensitivity Analysis of Muscle Activation Dynamics.

    PubMed

    Rockenfeller, Robert; Günther, Michael; Schmitt, Syn; Götz, Thomas

    2015-01-01

    We mathematically compared two models of mammalian striated muscle activation dynamics proposed by Hatze and Zajac. Both models are representative for a broad variety of biomechanical models formulated as ordinary differential equations (ODEs). These models incorporate parameters that directly represent known physiological properties. Other parameters have been introduced to reproduce empirical observations. We used sensitivity analysis to investigate the influence of model parameters on the ODE solutions. In addition, we expanded an existing approach to treating initial conditions as parameters and to calculating second-order sensitivities. Furthermore, we used a global sensitivity analysis approach to include finite ranges of parameter values. Hence, a theoretician striving for model reduction could use the method for identifying particularly low sensitivities to detect superfluous parameters. An experimenter could use it for identifying particularly high sensitivities to improve parameter estimation. Hatze's nonlinear model incorporates some parameters to which activation dynamics is clearly more sensitive than to any parameter in Zajac's linear model. Other than Zajac's model, Hatze's model can, however, reproduce measured shifts in optimal muscle length with varied muscle activity. Accordingly we extracted a specific parameter set for Hatze's model that combines best with a particular muscle force-length relation. PMID:26417379

  18. Comparative Sensitivity Analysis of Muscle Activation Dynamics

    PubMed Central

    Rockenfeller, Robert; Günther, Michael; Schmitt, Syn; Götz, Thomas

    2015-01-01

    We mathematically compared two models of mammalian striated muscle activation dynamics proposed by Hatze and Zajac. Both models are representative for a broad variety of biomechanical models formulated as ordinary differential equations (ODEs). These models incorporate parameters that directly represent known physiological properties. Other parameters have been introduced to reproduce empirical observations. We used sensitivity analysis to investigate the influence of model parameters on the ODE solutions. In addition, we expanded an existing approach to treating initial conditions as parameters and to calculating second-order sensitivities. Furthermore, we used a global sensitivity analysis approach to include finite ranges of parameter values. Hence, a theoretician striving for model reduction could use the method for identifying particularly low sensitivities to detect superfluous parameters. An experimenter could use it for identifying particularly high sensitivities to improve parameter estimation. Hatze's nonlinear model incorporates some parameters to which activation dynamics is clearly more sensitive than to any parameter in Zajac's linear model. Other than Zajac's model, Hatze's model can, however, reproduce measured shifts in optimal muscle length with varied muscle activity. Accordingly we extracted a specific parameter set for Hatze's model that combines best with a particular muscle force-length relation. PMID:26417379

  19. Effective field theory of dark energy: a dynamical analysis

    SciTech Connect

    Frusciante, Noemi; Raveri, Marco; Silvestri, Alessandra E-mail: mraveri@sissa.it

    2014-02-01

    The effective field theory (EFT) of dark energy relies on three functions of time to describe the dynamics of background cosmology. The viability of these functions is investigated here by means of a thorough dynamical analysis. While the system is underdetermined, and one can always find a set of functions reproducing any expansion history, we are able to determine general compatibility conditions for these functions by requiring a viable background cosmology. In particular, we identify a set of variables that allows us to transform the non-autonomous system of equations into an infinite-dimensional one characterized by a significant recursive structure. We then analyze several autonomous sub-systems, obtained truncating the original one at increasingly higher dimension, that correspond to increasingly general models of dark energy and modified gravity. Furthermore, we exploit the recursive nature of the system to draw some general conclusions on the different cosmologies that can be recovered within the EFT formalism and the corresponding compatibility requirements for the EFT functions. The machinery that we set up serves different purposes. It offers a general scheme for performing dynamical analysis of dark energy and modified gravity models within the model independent framework of EFT; the general results, obtained with this technique, can be projected into specific models, as we show in one example. It also can be used to determine appropriate ansätze for the three EFT background functions when studying the dynamics of cosmological perturbations in the context of large scale structure tests of gravity.

  20. Ongoing Analysis of Rocket Based Combined Cycle Engines by the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    Ruf, Joseph; Holt, James B.; Canabal, Francisco

    1999-01-01

    This paper presents the status of analyses on three Rocket Based Combined Cycle configurations underway in the Applied Fluid Dynamics Analysis Group (TD64). TD64 is performing computational fluid dynamics analysis on a Penn State RBCC test rig, the proposed Draco axisymmetric RBCC engine and the Trailblazer engine. The intent of the analysis on the Penn State test rig is to benchmark the Finite Difference Navier Stokes code for ejector mode fluid dynamics. The Draco engine analysis is a trade study to determine the ejector mode performance as a function of three engine design variables. The Trailblazer analysis is to evaluate the nozzle performance in scramjet mode. Results to date of each analysis are presented.

  1. Computational analysis of Variable Thrust Engine (VTE) performance

    NASA Technical Reports Server (NTRS)

    Giridharan, M. G.; Krishnan, A.; Przekwas, A. J.

    1993-01-01

    The Variable Thrust Engine (VTE) of the Orbital Maneuvering Vehicle (OMV) uses a hypergolic propellant combination of Monomethyl Hydrazine (MMH) and Nitrogen Tetroxide (NTO) as fuel and oxidizer, respectively. The performance of the VTE depends on a number of complex interacting phenomena such as atomization, spray dynamics, vaporization, turbulent mixing, convective/radiative heat transfer, and hypergolic combustion. This study involved the development of a comprehensive numerical methodology to facilitate detailed analysis of the VTE. An existing Computational Fluid Dynamics (CFD) code was extensively modified to include the following models: a two-liquid, two-phase Eulerian-Lagrangian spray model; a chemical equilibrium model; and a discrete ordinate radiation heat transfer model. The modified code was used to conduct a series of simulations to assess the effects of various physical phenomena and boundary conditions on the VTE performance. The details of the models and the results of the simulations are presented.

  2. Aero-Thermo-Dynamic Mass Analysis

    NASA Astrophysics Data System (ADS)

    Shiba, Kota; Yoshikawa, Genki

    2016-07-01

    Each gas molecule has its own molecular weight, while such a microscopic characteristic is generally inaccessible, and thus, it is measured indirectly through e.g. ionization in conventional mass analysis. Here, we present a novel approach to the direct measurement of molecular weight through a nanoarchitectonic combination of aerodynamics, thermodynamics, and mechanics, transducing microscopic events into macroscopic phenomena. It is confirmed that this approach can provide molecular weight of virtually any gas or vaporizable liquid sample in real-time without ionization. Demonstrations through analytical calculations, numerical simulations, and experiments verify the validity and versatility of the novel mass analysis realized by a simple setup with a flexible object (e.g. with a bare cantilever and even with a business card) placed in a laminar jet. Owing to its unique and simple working principle, this aero-thermo-dynamic mass analysis (AMA) can be integrated into various analytical devices, production lines, and consumer mobile platforms, opening new chapters in aerodynamics, thermodynamics, mechanics, and mass analysis.

  3. Aero-Thermo-Dynamic Mass Analysis.

    PubMed

    Shiba, Kota; Yoshikawa, Genki

    2016-01-01

    Each gas molecule has its own molecular weight, while such a microscopic characteristic is generally inaccessible, and thus, it is measured indirectly through e.g. ionization in conventional mass analysis. Here, we present a novel approach to the direct measurement of molecular weight through a nanoarchitectonic combination of aerodynamics, thermodynamics, and mechanics, transducing microscopic events into macroscopic phenomena. It is confirmed that this approach can provide molecular weight of virtually any gas or vaporizable liquid sample in real-time without ionization. Demonstrations through analytical calculations, numerical simulations, and experiments verify the validity and versatility of the novel mass analysis realized by a simple setup with a flexible object (e.g. with a bare cantilever and even with a business card) placed in a laminar jet. Owing to its unique and simple working principle, this aero-thermo-dynamic mass analysis (AMA) can be integrated into various analytical devices, production lines, and consumer mobile platforms, opening new chapters in aerodynamics, thermodynamics, mechanics, and mass analysis. PMID:27412335

  4. Aero-Thermo-Dynamic Mass Analysis

    PubMed Central

    Shiba, Kota; Yoshikawa, Genki

    2016-01-01

    Each gas molecule has its own molecular weight, while such a microscopic characteristic is generally inaccessible, and thus, it is measured indirectly through e.g. ionization in conventional mass analysis. Here, we present a novel approach to the direct measurement of molecular weight through a nanoarchitectonic combination of aerodynamics, thermodynamics, and mechanics, transducing microscopic events into macroscopic phenomena. It is confirmed that this approach can provide molecular weight of virtually any gas or vaporizable liquid sample in real-time without ionization. Demonstrations through analytical calculations, numerical simulations, and experiments verify the validity and versatility of the novel mass analysis realized by a simple setup with a flexible object (e.g. with a bare cantilever and even with a business card) placed in a laminar jet. Owing to its unique and simple working principle, this aero-thermo-dynamic mass analysis (AMA) can be integrated into various analytical devices, production lines, and consumer mobile platforms, opening new chapters in aerodynamics, thermodynamics, mechanics, and mass analysis. PMID:27412335

  5. Using Covariance Analysis to Assess Pointing Performance

    NASA Technical Reports Server (NTRS)

    Bayard, David; Kang, Bryan

    2009-01-01

    A Pointing Covariance Analysis Tool (PCAT) has been developed for evaluating the expected performance of the pointing control system for NASA s Space Interferometry Mission (SIM). The SIM pointing control system is very complex, consisting of multiple feedback and feedforward loops, and operating with multiple latencies and data rates. The SIM pointing problem is particularly challenging due to the effects of thermomechanical drifts in concert with the long camera exposures needed to image dim stars. Other pointing error sources include sensor noises, mechanical vibrations, and errors in the feedforward signals. PCAT models the effects of finite camera exposures and all other error sources using linear system elements. This allows the pointing analysis to be performed using linear covariance analysis. PCAT propagates the error covariance using a Lyapunov equation associated with time-varying discrete and continuous-time system matrices. Unlike Monte Carlo analysis, which could involve thousands of computational runs for a single assessment, the PCAT analysis performs the same assessment in a single run. This capability facilitates the analysis of parametric studies, design trades, and "what-if" scenarios for quickly evaluating and optimizing the control system architecture and design.

  6. Nonlinear dynamic analysis of hydrodynamically-coupled stainless steel structures

    SciTech Connect

    Zhao, Y.

    1996-12-01

    Spent nuclear fuel is usually stored temporarily on the site of nuclear power plants. The spent fuel storage racks are nuclear-safety-related stainless steel structures required to be analyzed for seismic loads. When the storage pool is subjected to three-dimensional (3-D) floor seismic excitations, rack modules, stored fuel bundles, adjacent racks and pool walls, and surrounding water are hydrodynamically coupled. Hydrodynamic coupling (HC) significantly affects the dynamic responses of the racks that are free-standing and submerged in water within the pool. A nonlinear time-history dynamic analysis is usually needed to describe the motion behavior of the racks that are both geometrically nonlinear and material nonlinear in nature. The nonlinearities include the friction resistance between the rack supporting legs and the pool floor, and various potential impacts of fuel-rack, rack-rack, and rack-pool wall. The HC induced should be included in the nonlinear dynamic analysis using the added-hydrodynamic-mass concept based on potential theory per the US Nuclear Regulatory Commission (USNRC) acceptance criteria. To this end, a finite element analysis constitutes a feasible and effective tool. However, most people perform somewhat simplified 1-D, or 2-D, or 3-D single rack and 2-D multiple rack analyses. These analyses are incomplete because a 3-D single rack model behaves quite differently from a 2-D mode. Furthermore, a 3-D whole pool multi-rack model behaves differently than a 3-D single rack model, especially when the strong HC effects are unsymmetrical. In this paper 3-D nonlinear dynamic time-history analyses were performed in a more quantitative manner using sophisticated finite element models developed for a single rack as well as all twelve racks in the whole-pool. Typical response results due to different HC effects are determined and discussed.

  7. Laser Atmospheric Wind Sounder (LAWS) performance analysis

    NASA Technical Reports Server (NTRS)

    Kenyon, D.; Petheram, J.

    1991-01-01

    The science objectives of the NASA's Laser Atmospheric Sounder (LAWS) are discussed, and results of the performance analysis of the LAWS system are presented together with the instrument configuration used for these performance analyses. The results of analyses show that the science requirements for the wind-velocity accuracies of m/sec in the lower troposphere and 5 m/sec in the upper troposphere will be met by the present design of the LAWS system. The paper presents the performance estimates of the LAWS in terms of the global coverage, spatial resolution, signal-to-noise ratio, line-of-sight velocity error, and horizontal inversion accuracy.

  8. Dynamic characterization and analysis of space shuttle SRM solid propellant

    NASA Technical Reports Server (NTRS)

    Hufferd, W. L.

    1979-01-01

    The dynamic response properties of the space shuttle solid rocket moter (TP-H1148) propellant were characterized and the expected limits of propellant variability were established. Dynamic shear modulus tests conducted on six production batches of TP-H1148 at various static and dynamic strain levels over the temperature range from 40 F to 90 F. A heat conduction analysis and dynamic response analysis of the space shuttle solid rocket motor (SRM) were also conducted. The dynamic test results show significant dependence on static and dynamic strain levels and considerable batch-to-batch and within-batch variability. However, the results of the SRM dynamic response analyses clearly demonstrate that the stiffness of the propellant has no consequential on the overall SRM dynamic response. Only the mass of the propellant needs to be considered in the dynamic analysis of the space shuttle SRM.

  9. Dynamic stall analysis of horizontal-axis-wind-turbine blades using computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Sayed, Mohamed A.; Kandil, Hamdy A.; Morgan, El-Sayed I.

    2012-06-01

    Dynamic stall has been widely known to significantly affect the performance of the wind turbines. In this paper, aerodynamic simulation of the unsteady low-speed flow past two-dimensional wind turbine blade profiles, developed by the National Renewable Energy Laboratory (NREL), will be performed. The aerodynamic simulation will be performed using Computational Fluid Dynamics (CFD). The governing equations used in the simulations are the Unsteady-Reynolds-Averaged-Navier-Stokes (URANS) equations. The unsteady separated turbulent flow around an oscillating airfoil pitching in a sinusoidal pattern in the regime of low Reynolds number is investigated numerically. The investigation employs the URANS approach with the most suitable turbulence model. The development of the light dynamic stall of the blades under consideration is studied. The S809 blade profile is simulated at different mean wind speeds. Moreover, the S826 blade profile is also considered for analysis of wind turbine blade which is the most suitable blade profile for the wind conditions in Egypt over the site of Gulf of El-Zayt. In order to find the best oscillating frequency, different oscillating frequencies are studied. The best frequency can then be used for the blade pitch controller. The comparisons with the experimental results showed that the used CFD code can accurately predict the blade profile unsteady aerodynamic loads.

  10. Perform - A performance optimizing computer program for dynamic systems subject to transient loadings

    NASA Technical Reports Server (NTRS)

    Pilkey, W. D.; Wang, B. P.; Yoo, Y.; Clark, B.

    1973-01-01

    A description and applications of a computer capability for determining the ultimate optimal behavior of a dynamically loaded structural-mechanical system are presented. This capability provides characteristics of the theoretically best, or limiting, design concept according to response criteria dictated by design requirements. Equations of motion of the system in first or second order form include incompletely specified elements whose characteristics are determined in the optimization of one or more performance indices subject to the response criteria in the form of constraints. The system is subject to deterministic transient inputs, and the computer capability is designed to operate with a large linear programming on-the-shelf software package which performs the desired optimization. The report contains user-oriented program documentation in engineering, problem-oriented form. Applications cover a wide variety of dynamics problems including those associated with such diverse configurations as a missile-silo system, impacting freight cars, and an aircraft ride control system.