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. 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.

  5. 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.

  6. Comparison of performance between rescaled range analysis and rescaled variance analysis in detecting abrupt dynamic change

    NASA Astrophysics Data System (ADS)

    He, Wen-Ping; Liu, Qun-Qun; Jiang, Yun-Di; Lu, Ying

    2015-04-01

    In the present paper, a comparison of the performance between moving cutting data-rescaled range analysis (MC-R/S) and moving cutting data-rescaled variance analysis (MC-V/S) is made. The results clearly indicate that the operating efficiency of the MC-R/S algorithm is higher than that of the MC-V/S algorithm. In our numerical test, the computer time consumed by MC-V/S is approximately 25 times that by MC-R/S for an identical window size in artificial data. Except for the difference in operating efficiency, there are no significant differences in performance between MC-R/S and MC-V/S for the abrupt dynamic change detection. MC-R/S and MC-V/S both display some degree of anti-noise ability. However, it is important to consider the influences of strong noise on the detection results of MC-R/S and MC-V/S in practical application processes. Project supported by the National Basic Research Program of China (Grant No. 2012CB955902) and the National Natural Science Foundation of China (Grant Nos. 41275074, 41475073, and 41175084).

  7. 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…

  8. Performance analysis and dynamic modeling of a single-spool turbojet engine

    NASA Astrophysics Data System (ADS)

    Andrei, Irina-Carmen; Toader, Adrian; Stroe, Gabriela; Frunzulica, Florin

    2017-01-01

    The purposes of modeling and simulation of a turbojet engine are the steady state analysis and transient analysis. From the steady state analysis, which consists in the investigation of the operating, equilibrium regimes and it is based on appropriate modeling describing the operation of a turbojet engine at design and off-design regimes, results the performance analysis, concluded by the engine's operational maps (i.e. the altitude map, velocity map and speed map) and the engine's universal map. The mathematical model that allows the calculation of the design and off-design performances, in case of a single spool turbojet is detailed. An in house code was developed, its calibration was done for the J85 turbojet engine as the test case. The dynamic modeling of the turbojet engine is obtained from the energy balance equations for compressor, combustor and turbine, as the engine's main parts. The transient analysis, which is based on appropriate modeling of engine and its main parts, expresses the dynamic behavior of the turbojet engine, and further, provides details regarding the engine's control. The aim of the dynamic analysis is to determine a control program for the turbojet, based on the results provided by performance analysis. In case of the single-spool turbojet engine, with fixed nozzle geometry, the thrust is controlled by one parameter, which is the fuel flow rate. The design and management of the aircraft engine controls are based on the results of the transient analysis. The construction of the design model is complex, since it is based on both steady-state and transient analysis, further allowing the flight path cycle analysis and optimizations. This paper presents numerical simulations for a single-spool turbojet engine (J85 as test case), with appropriate modeling for steady-state and dynamic analysis.

  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. Analysis of the temporal dynamics of model performance and parameter sensitivity for hydrological models

    NASA Astrophysics Data System (ADS)

    Reusser, D.; Zehe, E.

    2009-04-01

    The temporal dynamics of hydrological model performance gives insights into errors that cannot be obtained from global performance measures assigning a single number to the fit of a simulated time series to an observed reference series. These errors can include errors in data, model parameters, or model structure. Dealing with a set of performance measures evaluated at a high temporal resolution implies analyzing and interpreting a high dimensional data set. We present a method for such a hydrological model performance assessment with a high temporal resolution. Information about possible relevant processes during times with distinct model performance is obtained from parameter sensitivity analysis - also with high temporal resolution. We illustrate the combined approach of temporally resolved model performance and parameter sensitivity for a rainfall-runoff modeling case study. The headwater catchment of the Wilde Weisseritz in the eastern Ore mountains is simulated with the conceptual model WaSiM-ETH. The proposed time-resolved performance assessment starts with the computation of a large set of classically used performance measures for a moving window. The key of the developed approach is a data-reduction method based on self-organizing maps (SOMs) and cluster analysis to classify the high-dimensional performance matrix. Synthetic peak errors are used to interpret the resulting error classes. The temporally resolved sensitivity analysis is based on the FAST algorithm. The final outcome of the proposed method is a time series of the occurrence of dominant error types as well as a time series of the relative parameter sensitivity. For the two case studies analyzed here, 6 error types have been identified. They show clear temporal patterns which can lead to the identification of model structural errors. The parameter sensitivity helps to identify the relevant model parts.

  11. Performance of intensity-based non-normalized pointwise algorithms in dynamic speckle analysis.

    PubMed

    Stoykova, E; Nazarova, D; Berberova, N; Gotchev, A

    2015-09-21

    Intensity-based pointwise non-normalized algorithms for 2D evaluation of activity in optical metrology with dynamic speckle analysis are studied and compared. They are applied to a temporal sequence of correlated speckle patterns formed at laser illumination of the object surface. Performance of each algorithm is assessed through the histogram of estimates it produces. A new algorithm is proposed that provides the same quality of the 2D activity map for less computational effort. The algorithms are applied both to synthetic and experimental data.

  12. Performance Analysis of the AeroTP Transport Protocol for Highly-Dynamic Airborne Telemetry Networks

    DTIC Science & Technology

    2011-06-03

    Acknowledgment Options.” RFC 2018 (Proposed Standard ), Oct. 1996. [11] “The ns- 3 network simulator.” http://www.nsnam.org, July 2009. [12] M. AL-Enazi, S. A. Gogi...AFFTC-PA- 11146 Performance Analysis of the AeroTP Transport Protocol for Highly-Dynamic Airborne Telemetry Networks James P.G. Sterbenz...Kamakshi Sirisha Pathapati, Truc Anh N. Nguyen, Justin P. Rohrer AIR FORCE FLIGHT TEST CENTER EDWARDS AFB, CA JUNE 3 , 2011 A F F T C

  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. Analysis of the Temporal Dynamics of Model Performance for Hydrological Models

    NASA Astrophysics Data System (ADS)

    Reusser, D. E.; Blume, T.; Schaefli, B.; Zehe, E.

    2008-12-01

    The temporal dynamics of hydrological model performance gives insights into errors that cannot be obtained from global performance measures assigning a single number to the fit of a simulated time series to an observed reference series. These errors can include errors in in data, model parameters, or model structure. Dealing with a set of performance measures evaluated at a high temporal resolution implies analyzing and interpreting a high dimensional data set. We present a method for such a hydrological model performance assessment with a high temporal resolution and illustrate its application for two very different rainfall-runoff modeling case studies. The first is the Wilde Weisseritz case study, a headwater catchment in the eastern Ore Mountains, simulated with the conceptual model WaSiM-ETH. The second is the Malalcahuello case study, a headwater catchment in the Chilean Andes, simulated with the physics-based model Catflow. The proposed time-resolved performance assessment starts with the computation of a large set of classically used performance measures for a moving window. The key of the developed approach is a data-reduction method based on self-organizing maps (SOMs) and cluster analysis to classify the high-dimensional performance matrix. Synthetic peak errors are used to interpret the resulting error classes. The final outcome of the proposed method is a time series of the occurrence of dominant error types. For the two case studies analyzed here, 6 such error types have been identified. They show clear temporal patterns which can lead to the identification of model structural errors.

  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

    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.

  17. Performance Analysis of Control Signal Transmission Technique for Cognitive Radios in Dynamic Spectrum Access Networks

    NASA Astrophysics Data System (ADS)

    Sakata, Ren; Tomioka, Tazuko; Kobayashi, Takahiro

    When cognitive radio (CR) systems dynamically use the frequency band, a control signal is necessary to indicate which carrier frequencies are currently available in the network. In order to keep efficient spectrum utilization, this control signal also should be transmitted based on the channel conditions. If transmitters dynamically select carrier frequencies, receivers have to receive control signals without knowledge of their carrier frequencies. To enable such transmission and reception, this paper proposes a novel scheme called DCPT (Differential Code Parallel Transmission). With DCPT, receivers can receive low-rate information with no knowledge of the carrier frequencies. The transmitter transmits two signals whose carrier frequencies are spaced by a predefined value. The absolute values of the carrier frequencies can be varied. When the receiver acquires the DCPT signal, it multiplies the signal by a frequency-shifted version of the signal; this yields a DC component that represents the data signal which is then demodulated. The performance was evaluated by means of numerical analysis and computer simulation. We confirmed that DCPT operates successfully even under severe interference if its parameters are appropriately configured.

  18. Performance Evaluation of Counter-Based Dynamic Load Balancing Schemes for Massive Contingency Analysis with Different Computing Environments

    SciTech Connect

    Chen, Yousu; Huang, Zhenyu; Chavarría-Miranda, Daniel

    2010-09-30

    Contingency analysis is a key function in the Energy Management System (EMS) to assess the impact of various combinations of power system component failures based on state estimation. Contingency analysis is also extensively used in power market operation for feasibility test of market solutions. High performance computing holds the promise of faster analysis of more contingency cases for the purpose of safe and reliable operation of today’s power grids with less operating margin and more intermittent renewable energy sources. This paper evaluates the performance of counter-based dynamic load balancing schemes for massive contingency analysis under different computing environments. Insights from the performance evaluation can be used as guidance for users to select suitable schemes in the application of massive contingency analysis. Case studies, as well as MATLAB simulations, of massive contingency cases using the Western Electricity Coordinating Council power grid model are presented to illustrate the application of high performance computing with counter-based dynamic load balancing schemes.

  19. An Examination of the Dynamic Relationship between Self-Efficacy and Performance across Levels of Analysis and Levels of Specificity

    ERIC Educational Resources Information Center

    Yeo, Gillian B.; Neal, Andrew

    2006-01-01

    This research used resource allocation theory to generate predictions regarding dynamic relationships between self-efficacy and task performance from 2 levels of analysis and specificity. Participants were given multiple trials of practice on an air traffic control task. Measures of task-specific self-efficacy and performance were taken at…

  20. 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

  1. Seismic Performance Evaluation of the Jacket Type Offshore Platforms through Incremental Dynamic Analysis considering Soil-Pile-Structure Interaction

    SciTech Connect

    Asgarian, Behrouz; Shokrgozar, Hamed R.; Talarposhti, Ali Shakeri

    2008-07-08

    Of great interest in Performance-Based Earthquake Engineering (PBEE) is the accurate estimation of the seismic performance of structures. A performance prediction and evaluation procedure is based on nonlinear dynamics and reliability theory. In this method, a full integration over the three key stochastic models is as follow: ground motion hazard curve, nonlinear dynamic displacement demand, and displacement capacity. Further, both epistemic and aleatory uncertainties are evaluated and carried through the analysis.In this paper, jacket and soil-pile system have been modeled using Finite Element program (OpenSees) and the incremental dynamic analysis (IDA) are performed to investigate nonlinear behavior of offshore platforms. The system demand is determined by performing time history response analyses of the jacket under a suite of FEMA/SAC uniform hazard ground motions. The system capacity in terms of the drift ratio against incipient collapse is generally difficult to predict since the structural response goes into nonlinear range before collapse. All the analyses are performed in two directions and the results are compared with each others. The confidence level of a jacket in each direction for a given hazard level is calculated using the procedure described.

  2. Seismic Performance Evaluation of the Jacket Type Offshore Platforms through Incremental Dynamic Analysis considering Soil-Pile-Structure Interaction

    NASA Astrophysics Data System (ADS)

    Asgarian, Behrouz; Shokrgozar, Hamed R.; Talarposhti, Ali Shakeri

    2008-07-01

    Of great interest in Performance-Based Earthquake Engineering (PBEE) is the accurate estimation of the seismic performance of structures. A performance prediction and evaluation procedure is based on nonlinear dynamics and reliability theory. In this method, a full integration over the three key stochastic models is as follow: ground motion hazard curve, nonlinear dynamic displacement demand, and displacement capacity. Further, both epistemic and aleatory uncertainties are evaluated and carried through the analysis. In this paper, jacket and soil-pile system have been modeled using Finite Element program (OpenSees) and the incremental dynamic analysis (IDA) are performed to investigate nonlinear behavior of offshore platforms. The system demand is determined by performing time history response analyses of the jacket under a suite of FEMA/SAC uniform hazard ground motions. The system capacity in terms of the drift ratio against incipient collapse is generally difficult to predict since the structural response goes into nonlinear range before collapse. All the analyses are performed in two directions and the results are compared with each others. The confidence level of a jacket in each direction for a given hazard level is calculated using the procedure described.

  3. 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.

  4. 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.

  5. Analysis of dynamic testing performed on structural clay tile infilled frames

    SciTech Connect

    Fowler, Joele Johnston

    1994-12-18

    The behavior of two structural clay tile infilled frames subjected to dynamic loading is investigated. The testing was performed by USACERL using a biaxial shake table machine on which two framed infills were spaced nine feet apart and connected by steel trusses and an eight inch concrete roof slab. The infills were composed of structural clay tile block which were laid with the cores horizontal. The specimen was loaded in both the out-of-plane and in-plane directions using a site specific time history record. The testing focused on determining frame and panel load-deflection behavior, acceleration amplification, and frequency degradation characteristics. The out-of-plane tests resulted in little degradation of frequency which means there was little loss of stiffness. There was no evidence of the infill {open_quotes}walking-out{close_quotes} of the steel frame; in fact the infill still had substantial stability after completion of the out-of-plane tests. As a result of the gradual increase in ground motion in the in-plane testing, the stiffness of the specimen gradually decreased. Strength and stiffness characteristics obtained from the dynamic testing were comparable to results and behavior seen in static tests. Degradation in the panel was much more rapid under the stronger ground motions which were produced during the sine sweep tests.

  6. Dynamics in Epistasis Analysis.

    PubMed

    Awdeh, Aseel; Phenix, Hilary; Kaern, Mads; Perkins, Theodore

    2017-01-16

    Finding regulatory relationships between genes, including the direction and nature of influence between them, is a fundamental challenge in the field of molecular genetics. One classical approach to this problem is epistasis analysis. Broadly speaking, epistasis analysis infers the regulatory relationships between a pair of genes in a genetic pathway by considering the patterns of change in an observable trait resulting from single and double deletion of genes. While classical epistasis analysis has yielded deep insights on numerous genetic pathways, it is not without limitations. Here, we explore the possibility of dynamic epistasis analysis, in which, in addition to performing genetic perturbations of a pathway, we drive the pathway by a time-varying upstream signal. We explore the theoretical power of dynamical epistasis analysis by conducting an identifiability analysis of Boolean models of genetic pathways, comparing static and dynamic approaches. We find that even relatively simple input dynamics greatly increases the power of epistasis analysis to discriminate alternative network structures. Further, we explore the question of experiment design, and show that a subset of short time-varying signals, which we call dynamic primitives, allow maximum discriminative power with a reduced number of experiments.

  7. Dynamic statistical optimization of GNSS radio occultation bending angles: advanced algorithm and performance analysis

    NASA Astrophysics Data System (ADS)

    Li, Y.; Kirchengast, G.; Scherllin-Pirscher, B.; Norman, R.; Yuan, Y. B.; Fritzer, J.; Schwaerz, M.; Zhang, K.

    2015-08-01

    We introduce a new dynamic statistical optimization algorithm to initialize ionosphere-corrected bending angles of Global Navigation Satellite System (GNSS)-based radio occultation (RO) measurements. The new algorithm estimates background and observation error covariance matrices with geographically varying uncertainty profiles and realistic global-mean correlation matrices. The error covariance matrices estimated by the new approach are more accurate and realistic than in simplified existing approaches and can therefore be used in statistical optimization to provide optimal bending angle profiles for high-altitude initialization of the subsequent Abel transform retrieval of refractivity. The new algorithm is evaluated against the existing Wegener Center Occultation Processing System version 5.6 (OPSv5.6) algorithm, using simulated data on two test days from January and July 2008 and real observed CHAllenging Minisatellite Payload (CHAMP) and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) measurements from the complete months of January and July 2008. The following is achieved for the new method's performance compared to OPSv5.6: (1) significant reduction of random errors (standard deviations) of optimized bending angles down to about half of their size or more; (2) reduction of the systematic differences in optimized bending angles for simulated MetOp data; (3) improved retrieval of refractivity and temperature profiles; and (4) realistically estimated global-mean correlation matrices and realistic uncertainty fields for the background and observations. Overall the results indicate high suitability for employing the new dynamic approach in the processing of long-term RO data into a reference climate record, leading to well-characterized and high-quality atmospheric profiles over the entire stratosphere.

  8. Dynamic statistical optimization of GNSS radio occultation bending angles: an advanced algorithm and its performance analysis

    NASA Astrophysics Data System (ADS)

    Li, Y.; Kirchengast, G.; Scherllin-Pirscher, B.; Norman, R.; Yuan, Y. B.; Fritzer, J.; Schwaerz, M.; Zhang, K.

    2015-01-01

    We introduce a new dynamic statistical optimization algorithm to initialize ionosphere-corrected bending angles of Global Navigation Satellite System (GNSS) based radio occultation (RO) measurements. The new algorithm estimates background and observation error covariance matrices with geographically-varying uncertainty profiles and realistic global-mean correlation matrices. The error covariance matrices estimated by the new approach are more accurate and realistic than in simplified existing approaches and can therefore be used in statistical optimization to provide optimal bending angle profiles for high-altitude initialization of the subsequent Abel transform retrieval of refractivity. The new algorithm is evaluated against the existing Wegener Center Occultation Processing System version 5.6 (OPSv5.6) algorithm, using simulated data on two test days from January and July 2008 and real observed CHAMP and COSMIC measurements from the complete months of January and July 2008. The following is achieved for the new method's performance compared to OPSv5.6: (1) significant reduction in random errors (standard deviations) of optimized bending angles down to about two-thirds of their size or more; (2) reduction of the systematic differences in optimized bending angles for simulated MetOp data; (3) improved retrieval of refractivity and temperature profiles; (4) produces realistically estimated global-mean correlation matrices and realistic uncertainty fields for the background and observations. Overall the results indicate high suitability for employing the new dynamic approach in the processing of long-term RO data into a reference climate record, leading to well characterized and high-quality atmospheric profiles over the entire stratosphere.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Energy Performance Analysis of Pelotint Dynamic Sun Responsive Thermochromic (SRT) Windows

    NASA Astrophysics Data System (ADS)

    Surel, Ali

    This study presents the energy performance test results of the Pleotint Sun Responsive Thermochromic (SRT) windows by using the Iowa Energy Center Energy Resource Station (ERS) test systems and data acquisition resources. The data includes experimental test results by using the ERS test, instrumentation and data acquisition resources. The experimental procedures were conducted under controlled environments. The controlled environments consists of test rooms, office space, air handling units and air cooled chillers. The weather data were also collected at the facility and used for both experimental and simulation test procedures. The experimental performance results presented in this thesis for the SRT windows include the analysis of natural gas and electricity energy use for heating loads, cooling loads, pump energy, fan energy and lighting energy at the test room level. Considering energy efficiency, the results of this study show that Pleotint SRT window technology can save more energy compared to Low-E dark tinted performance windows while still satisfying comfort level requirements. The results of the study show that most of the energy savings were from lighting energy compared to cooling and heating loads.

  14. 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.

  15. 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…

  16. 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.

  17. 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…

  18. Dynamic information flow analysis in Vascular Dementia patients during the performance of a visual oddball task.

    PubMed

    Wang, Chao; Xu, Jin; Lou, Wutao; Zhao, Songzhen

    2014-09-19

    This study investigated the information flow in patients with Vascular Dementia (VaD). Twelve VaD patients and twelve age-matched controls participated in the study. EEG signal was recorded when subjects were performing a visual oddball task. Information flow was analyzed between 9 electrodes in frontal, central, and parietal lobes using short-window Directed Transfer Function (sDTF). VaD patients presented a significant decline in the information flow from parietal to frontal and central lobes, compared with the healthy elderly. This decline mainly occurred in delta, theta, and lower alpha bands, from about 200ms to 300ms after target stimulus onset. The findings indicated an impaired parietal-to-frontal and parietal-to-central connectivity in VaD patients, which may be one reason for the cognitive deficits in VaD patients.

  19. 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.

  20. 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

    2016-05-12

    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.

  1. 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

  2. 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.

  3. Performance analysis of slope-assisted dynamic BOTDA based on Brillouin gain or phase-shift in optical fibers

    NASA Astrophysics Data System (ADS)

    Tu, Xiaobo; Luo, Hong; Sun, Qiao; Hu, Xiaoyang; Meng, Zhou

    2015-10-01

    This paper analyzes the performance of the slope-assisted dynamic BOTDA based on Brillouin gain or phase-shift in an experiment. Dynamic strains with frequency of 60 Hz are successfully measured with an effective sensing rate of 1 kHz over a 46 m sensing fiber in both schemes. The dynamic ranges of these two schemes are measured to be about 47 MHz (940 μ \\varepsilon ), through dynamic strain measurements while linearly sweeping the work point. The optimum work point for Brillouin gain is theoretically and experimentally proved to be {ν }B+/- \\sqrt{3}{{Δ }}{ν }B/6, not {ν }B+/- {{Δ }}{ν }B/2 as commonly known, where {ν }B corresponds to the Brillouin frequency shift and {{Δ }}{ν }B is the Brillouin linewidth. The distortion factors are also measured to stay in a quite low level in the dynamic range. These results will provide guidelines for practical dynamic strain measurements and to further improve the performance of the slope-assisted BOTDA systems.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Structural dynamics analysis

    NASA Technical Reports Server (NTRS)

    Housner, J. M.; Anderson, M.; Belvin, W.; Horner, G.

    1985-01-01

    Dynamic analysis of large space antenna systems must treat the deployment as well as vibration and control of the deployed antenna. Candidate computer programs for deployment dynamics, and issues and needs for future program developments are reviewed. Some results for mast and hoop deployment are also presented. Modeling of complex antenna geometry with conventional finite element methods and with repetitive exact elements is considered. Analytical comparisons with experimental results for a 15 meter hoop/column antenna revealed the importance of accurate structural properties including nonlinear joints. Slackening of cables in this antenna is also a consideration. The technology of designing actively damped structures through analytical optimization is discussed and results are presented.

  9. Holley Stick Performance Analysis

    DTIC Science & Technology

    2013-04-01

    TECHNICAL REPORT 2015 April 2013 Holley Stick Performance Analysis Steven T. Holste , Ph.D Jeffrey J. Person...Performance Analysis Steven T. Holste , PhD. Jeffrey J. Person Approved for public release...IEDs on U.S. and coalition forces. Figure 2 depicts OEF casualties from 2008 through 2012, indicating Total and IED-caused Killed in Action (KIA

  10. Dynamic Contingency Analysis Tool

    SciTech Connect

    2016-01-14

    The Dynamic Contingency Analysis Tool (DCAT) is an open-platform and publicly available methodology to help develop applications that aim to improve the capabilities of power system planning engineers to assess the impact and likelihood of extreme contingencies and potential cascading events across their systems and interconnections. Outputs from the DCAT will help find mitigation solutions to reduce the risk of cascading outages in technically sound and effective ways. The current prototype DCAT implementation has been developed as a Python code that accesses the simulation functions of the Siemens PSS�E planning tool (PSS/E). It has the following features: It uses a hybrid dynamic and steady-state approach to simulating the cascading outage sequences that includes fast dynamic and slower steady-state events. It integrates dynamic models with protection scheme models for generation, transmission, and load. It models special protection systems (SPSs)/remedial action schemes (RASs) and automatic and manual corrective actions. Overall, the DCAT attempts to bridge multiple gaps in cascading-outage analysis in a single, unique prototype tool capable of automatically simulating and analyzing cascading sequences in real systems using multiprocessor computers.While the DCAT has been implemented using PSS/E in Phase I of the study, other commercial software packages with similar capabilities can be used within the DCAT framework.

  11. 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.

  12. 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.…

  13. A simplified method in comparison with comprehensive interaction incremental dynamic analysis to assess seismic performance of jacket-type offshore platforms

    NASA Astrophysics Data System (ADS)

    Zolfaghari, M. R.; Ajamy, A.; Asgarian, B.

    2015-12-01

    The primary goal of seismic reassessment procedures in oil platform codes is to determine the reliability of a platform under extreme earthquake loading. Therefore, in this paper, a simplified method is proposed to assess seismic performance of existing jacket-type offshore platforms (JTOP) in regions ranging from near-elastic to global collapse. The simplified method curve exploits well agreement between static pushover (SPO) curve and the entire summarized interaction incremental dynamic analysis (CI-IDA) curve of the platform. Although the CI-IDA method offers better understanding and better modelling of the phenomenon, it is a time-consuming and challenging task. To overcome the challenges, the simplified procedure, a fast and accurate approach, is introduced based on SPO analysis. Then, an existing JTOP in the Persian Gulf is presented to illustrate the procedure, and finally a comparison is made between the simplified method and CI-IDA results. The simplified method is very informative and practical for current engineering purposes. It is able to predict seismic performance elasticity to global dynamic instability with reasonable accuracy and little computational effort.

  14. Variable Dynamic Testbed Vehicle: Dynamics Analysis

    NASA Technical Reports Server (NTRS)

    Lee, A. Y.; Le, N. T.; Marriott, A. T.

    1997-01-01

    The Variable Dynamic Testbed Vehicle (VDTV) concept has been proposed as a tool to evaluate collision avoidance systems and to perform driving-related human factors research. The goal of this study is to analytically investigate to what extent a VDTV with adjustable front and rear anti-roll bar stiffnesses, programmable damping rates, and four-wheel-steering can emulate the lateral dynamics of a broad range of passenger vehicles.

  15. DIDA - Dynamic Image Disparity Analysis.

    DTIC Science & Technology

    1982-12-31

    Understanding, Dynamic Image Analysis , Disparity Analysis, Optical Flow, Real-Time Processing ___ 20. ABSTRACT (Continue on revere side If necessary aid identify...three aspects of dynamic image analysis must be studied: effectiveness, generality, and efficiency. In addition, efforts must be made to understand the...environment. A better understanding of the need for these Limiting constraints is required. Efficiency is obviously important if dynamic image analysis is

  16. 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.

  17. 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.

  18. 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

  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. 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.

  1. 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.

  2. Bioreactor performance and quantitative analysis of methanogenic and bacterial community dynamics in microbial electrolysis cells during large temperature fluctuations.

    PubMed

    Lu, Lu; Xing, Defeng; Ren, Nanqi

    2012-06-19

    The use of microbial electrolysis cells (MECs) for H(2) production generally finds H(2) sink by undesirable methanogenesis at mesophilic temperatures. Previously reported approaches failed to effectively inhibit methanogenesis without the addition of nongreen chemical inhibitors. Here, we demonstrated that the CH(4) production and the number of methanogens in single-chamber MECs could be restricted steadily to a negligible level by continuously operating reactors at the relatively low temperature of 15 °C. This resulted in a H(2) yield and production rate comparable to those obtained at 30 °C with less CH(4) production (CH(4)% < 1%). However, this operation at 15 °C should be taken from the initial stage of anodic biofilm formation, when the methanogenic community has not yet been established sufficiently. Maintaining MECs operating at 20 °C was not effective for controlling methanogenesis. The varying degrees of methanogenesis observed in MECs at 30 °C could be completely inhibited at 4 and 9 °C, and the total number of methanogens (mainly hydrogenotrophic methanogens) could be reduced by 68-91% during 32-55 days of operation at the low temperatures. However, methanogens cannot be eliminated completely at these temperatures. After the temperature is returned to 30 °C, the CH(4) production and the number of total methanogens can rapidly rise to the prior levels. Analysis of bacterial communities using 454 pyrosequencing showed that changes in temperature had no a substantial impact on composition of dominant electricity-producing bacteria ( Geobacter ). The results of our study provide more information toward understanding the temperature-dependent control of methanogenesis in MECs.

  3. 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.

  4. 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

  5. Performance analysis in saber.

    PubMed

    Aquili, Andrea; Tancredi, Virginia; Triossi, Tamara; De Sanctis, Desiree; Padua, Elvira; DʼArcangelo, Giovanna; Melchiorri, Giovanni

    2013-03-01

    Fencing is a sport practiced by both men and women, which uses 3 weapons: foil, épée, and saber. In general, there are few scientific studies available in international literature; they are limited to the performance analysis of fencing bouts, yet there is nothing about saber. There are 2 kinds of competitions in the World Cup for both men and women: the "FIE GP" and "A." The aim of this study was to carry out a saber performance analysis to gain useful indicators for the definition of a performance model. In addition, it is expected to verify if it could be influenced by the type of competition and if there are differences between men and women. Sixty bouts: 33 FIE GP and 27 "A" competitions (35 men's and 25 women's saber bouts) were analyzed. The results indicated that most actions are offensive (55% for men and 49% for women); the central area of the piste is mostly used (72% for men and 67% for women); the effective fighting time is 13.6% for men and 17.1% for women, and the ratio between the action and break times is 1:6.5 for men and 1:5.1 for women. A lunge is carried out every 23.9 seconds by men and every 20 seconds by women, and a direction change is carried out every 65.3 seconds by men and every 59.7 seconds by women. The data confirm the differences between the saber and the other 2 weapons. There is no significant difference between the data of the 2 different kinds of competitions.

  6. 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.

  7. Random Matrix Theory in molecular dynamics analysis.

    PubMed

    Palese, Luigi Leonardo

    2015-01-01

    It is well known that, in some situations, principal component analysis (PCA) carried out on molecular dynamics data results in the appearance of cosine-shaped low index projections. Because this is reminiscent of the results obtained by performing PCA on a multidimensional Brownian dynamics, it has been suggested that short-time protein dynamics is essentially nothing more than a noisy signal. Here we use Random Matrix Theory to analyze a series of short-time molecular dynamics experiments which are specifically designed to be simulations with high cosine content. We use as a model system the protein apoCox17, a mitochondrial copper chaperone. Spectral analysis on correlation matrices allows to easily differentiate random correlations, simply deriving from the finite length of the process, from non-random signals reflecting the intrinsic system properties. Our results clearly show that protein dynamics is not really Brownian also in presence of the cosine-shaped low index projections on principal axes.

  8. Dynamic stretching and golf swing performance.

    PubMed

    Moran, K A; McGrath, T; Marshall, B M; Wallace, E S

    2009-02-01

    The aim of the present study was to examine the effect of dynamic stretching, static stretching and no stretching, as part of a general warm-up, on golf swing performance with a five-iron. Measures of performance were taken 0 min, 5 min, 15 min and 30 min after stretching. Dynamic stretching produced significantly greater club head speeds than both static stretching (Delta=1.9m.s (-1); p=0.000) and no stretching (Delta=1.7 m.s (-1); p=0.000), and greater ball speeds than both static stretching (Delta=3.5m.s (-1); p=0.003) and no stretching (Delta=3.3m.s (-1); p=0.001). Dynamic stretching produced significantly straighter swing-paths than both static stretching (Delta=-0.61 degrees , p=0.000) and no stretching (Delta=-0.72 degrees , p=0.01). Dynamic stretching also produced more central impact points than the static stretch (Delta=0.7 cm, p=0.001). For the club face angle, there was no effect of either stretch or time. For all of the variables measured, there was no significant difference between the static stretch and no stretch conditions. All of the results were unaffected by the time of measurement after stretching. The results indicate that dynamic stretching should be used as part of a general warm-up in golf.

  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. Dynamical pathway analysis

    PubMed Central

    Xiong, Hao; Choe, Yoonsuck

    2008-01-01

    Background Although a great deal is known about one gene or protein and its functions under different environmental conditions, little information is available about the complex behaviour of biological networks subject to different environmental perturbations. Observing differential expressions of one or more genes between normal and abnormal cells has been a mainstream method of discovering pertinent genes in diseases and therefore valuable drug targets. However, to date, no such method exists for elucidating and quantifying the differential dynamical behaviour of genetic regulatory networks, which can have greater impact on phenotypes than individual genes. Results We propose to redress the deficiency by formulating the functional study of biological networks as a control problem of dynamical systems. We developed mathematical methods to study the stability, the controllability, and the steady-state behaviour, as well as the transient responses of biological networks under different environmental perturbations. We applied our framework to three real-world datasets: the SOS DNA repair network in E. coli under different dosages of radiation, the GSH redox cycle in mice lung exposed to either poisonous air or normal air, and the MAPK pathway in mammalian cell lines exposed to three types of HIV type I Vpr, a wild type and two mutant types; and we found that the three genetic networks exhibited fundamentally different dynamical properties in normal and abnormal cells. Conclusion Difference in stability, relative stability, degrees of controllability, and transient responses between normal and abnormal cells means considerable difference in dynamical behaviours and different functioning of cells. Therefore differential dynamical properties can be a valuable tool in biomedical research. PMID:18221557

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

    PubMed

    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.

  13. 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.

  14. 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.

  15. Probabilistic assessment of dynamic system performance. Part 3

    SciTech Connect

    Belhadj, Mohamed

    1993-01-01

    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.

  16. 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.

  17. 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.

  18. 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.

  19. Assessing the performance of dynamical trajectory estimates

    NASA Astrophysics Data System (ADS)

    Bröcker, Jochen

    2014-06-01

    Estimating trajectories and parameters of dynamical systems from observations is a problem frequently encountered in various branches of science; geophysicists for example refer to this problem as data assimilation. Unlike as in estimation problems with exchangeable observations, in data assimilation the observations cannot easily be divided into separate sets for estimation and validation; this creates serious problems, since simply using the same observations for estimation and validation might result in overly optimistic performance assessments. To circumvent this problem, a result is presented which allows us to estimate this optimism, thus allowing for a more realistic performance assessment in data assimilation. The presented approach becomes particularly simple for data assimilation methods employing a linear error feedback (such as synchronization schemes, nudging, incremental 3DVAR and 4DVar, and various Kalman filter approaches). Numerical examples considering a high gain observer confirm the theory.

  20. Assessing the performance of dynamical trajectory estimates.

    PubMed

    Bröcker, Jochen

    2014-06-01

    Estimating trajectories and parameters of dynamical systems from observations is a problem frequently encountered in various branches of science; geophysicists for example refer to this problem as data assimilation. Unlike as in estimation problems with exchangeable observations, in data assimilation the observations cannot easily be divided into separate sets for estimation and validation; this creates serious problems, since simply using the same observations for estimation and validation might result in overly optimistic performance assessments. To circumvent this problem, a result is presented which allows us to estimate this optimism, thus allowing for a more realistic performance assessment in data assimilation. The presented approach becomes particularly simple for data assimilation methods employing a linear error feedback (such as synchronization schemes, nudging, incremental 3DVAR and 4DVar, and various Kalman filter approaches). Numerical examples considering a high gain observer confirm the theory.

  1. Using Human Dynamics to Improve Operator Performance

    NASA Astrophysics Data System (ADS)

    Antunes, Rui; Coito, Fernando V.; Duarte-Ramos, Hermínio

    Traditionally Man-Machine Interfaces (MMI) are concerned with the ergonomic aspects of the operation, often disregarding other aspects on how humans learn and use machines. The explicit use of the operator dynamics characterization for the definition of the Human-in-the-Loop control system may allow an improved performance for manual control systems. The proposed human model depends on the activity to be performed and the mechanical Man-Machine Interface. As a first approach for model development, a number of 1-D manual tracking experiments were evaluated, using an analog Joystick. A simple linear human model was obtained and used to design an improved closed-loop control structure. This paper describes practical aspects of an ongoing PhD work on cognitive control in Human-Machine systems.

  2. 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.

  3. 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.

  4. Nonlinear analysis of dynamic signature

    NASA Astrophysics Data System (ADS)

    Rashidi, S.; Fallah, A.; Towhidkhah, F.

    2013-12-01

    Signature is a long trained motor skill resulting in well combination of segments like strokes and loops. It is a physical manifestation of complex motor processes. The problem, generally stated, is that how relative simplicity in behavior emerges from considerable complexity of perception-action system that produces behavior within an infinitely variable biomechanical and environmental context. To solve this problem, we present evidences which indicate that motor control dynamic in signing process is a chaotic process. This chaotic dynamic may explain a richer array of time series behavior in motor skill of signature. Nonlinear analysis is a powerful approach and suitable tool which seeks for characterizing dynamical systems through concepts such as fractal dimension and Lyapunov exponent. As a result, they can be analyzed in both horizontal and vertical for time series of position and velocity. We observed from the results that noninteger values for the correlation dimension indicates low dimensional deterministic dynamics. This result could be confirmed by using surrogate data tests. We have also used time series to calculate the largest Lyapunov exponent and obtain a positive value. These results constitute significant evidence that signature data are outcome of chaos in a nonlinear dynamical system of motor control.

  5. 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.

  6. 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.

  7. Dynamic performance of slender suspension footbridges under eccentric walking dynamic loads

    NASA Astrophysics Data System (ADS)

    Huang, Ming-Hui; Thambiratnam, David P.; Perera, Nimal J.

    2007-06-01

    This paper treats the vibration of slender suspension footbridges caused by eccentrically distributed walking dynamic loads. A suspension footbridge model with reverse profiled cables in both the vertical and horizontal planes was used in this conceptual study, while SAP2000 package is adopted in the numerical analysis. The dynamic behaviour of slender footbridges under walking dynamic loads is simulated by resonant vibration caused by synchronous excitations. It is found that slender suspension footbridges with shallow cable profiles often have coupled vibration modes such as coupled lateral-torsional or coupled torsional-lateral modes. When these coupled vibration modes are excited by walking pedestrians, excessive lateral vibration can be induced. Results also show that the effects of the reverse profiled cables on the dynamic performance in different vibration modes are complex. Reverse profiled cables in the horizontal plane can significantly suppress the lateral vibration in coupled lateral-torsional modes, but slightly increase the lateral vibration in coupled torsional-lateral modes.

  8. 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.

  9. 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)

  10. Wavelet Analysis for Molecular Dynamics

    DTIC Science & Technology

    2015-06-01

    simulation (and the computational work performed in the process). Slower processes, such as torsions and translations, are usually the more relevant ones. The...is no longer as simple as for H2O, nor are the eigenvalues except 0 simple; for the generalized Amber force field (GAFF), they are 14.7 and...short-range molecular dynamics. J Comput Phys. 1995;117(1):1–19. 9. Sun H, Mumby SJ, Maple JR, Hagler AT. An ab initio CFF93 all-atom force field for

  11. Dynamic Task Performance, Cohesion, and Communications in Human Groups.

    PubMed

    Giraldo, Luis Felipe; Passino, Kevin M

    2016-10-01

    In the study of the behavior of human groups, it has been observed that there is a strong interaction between the cohesiveness of the group, its performance when the group has to solve a task, and the patterns of communication between the members of the group. Developing mathematical and computational tools for the analysis and design of task-solving groups that are not only cohesive but also perform well is of importance in social sciences, organizational management, and engineering. In this paper, we model a human group as a dynamical system whose behavior is driven by a task optimization process and the interaction between subsystems that represent the members of the group interconnected according to a given communication network. These interactions are described as attractions and repulsions among members. We show that the dynamics characterized by the proposed mathematical model are qualitatively consistent with those observed in real-human groups, where the key aspect is that the attraction patterns in the group and the commitment to solve the task are not static but change over time. Through a theoretical analysis of the system we provide conditions on the parameters that allow the group to have cohesive behaviors, and Monte Carlo simulations are used to study group dynamics for different sets of parameters, communication topologies, and tasks to solve.

  12. 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.

  13. Nonlinear analysis of drought dynamics

    NASA Astrophysics Data System (ADS)

    Ma, M.

    2015-12-01

    Drought is an extreme natural hazard and becomes a severe problem in the world. It arises as a result of interactions between climate input and human activity, displaying the nonlinearity and complexity. Nonlinear time series analyses open a way to study the underlying dynamic characteristics of drought, and then provide the forward knowledge to understanding the physical mechanism of drought event. The rationale behind this idea is that information about the representation of nonlinear properties could be used as an additional quality indicator. To that end, the correlation dimension method, a powerful nonlinear time series analysis method based on the chaos theory, has been suggested to assess the intrinsic dimensionality or degree of freedom of time series according to Takens (1981). It can provide an assessment of the dominant processes that is required to map the observed dynamics. In this study, daily discharge and hourly groundwater level data of 63 catchments in Germany and China were investigated with correlation dimension method. The results indicated that the correlation dimension values of studied discharge exhibited none clear spatial patterns, but showed significant correlations with the spatial heterogeneity within the catchments. In contrast, the correlation dimension values of groundwater level displayed spatial patterns due to the different aquifer conditions (confined or unconfined). High correlation dimension values indicate partly confined conditions. In addition, Hurst analysis was involved to qualify the persistence of drought. It seems that drought mechanisms can be learnt from the data themselves in an inverse manner.

  14. 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.

  15. Quantitative kinetic analysis of lung nodules using the temporal subtraction technique in dynamic chest radiographies performed with a flat panel detector.

    PubMed

    Tsuchiya, Yuichiro; Kodera, Yoshie; Tanaka, Rie; Sanada, Shigeru

    2009-04-01

    Early detection and treatment of lung cancer is one of the most effective means of reducing cancer mortality, and to this end, chest X-ray radiography has been widely used as a screening method. A related technique based on the development of computer analysis and a flat panel detector (FPD) has enabled the functional evaluation of respiratory kinetics in the chest and is expected to be introduced into clinical practice in the near future. In this study, we developed a computer analysis algorithm to detect lung nodules and to evaluate quantitative kinetics. Breathing chest radiographs obtained by modified FPD and breath synchronization utilizing diaphragmatic analysis of vector movement were converted into four static images by sequential temporal subtraction processing, morphological enhancement processing, kinetic visualization processing, and lung region detection processing. An artificial neural network analyzed these density patterns to detect the true nodules and draw their kinetic tracks. Both the algorithm performance and the evaluation of clinical effectiveness of seven normal patients and simulated nodules showed sufficient detecting capability and kinetic imaging function without significant differences. Our technique can quantitatively evaluate the kinetic range of nodules and is effective in detecting a nodule on a breathing chest radiograph. Moreover, the application of this technique is expected to extend computer-aided diagnosis systems and facilitate the development of an automatic planning system for radiation therapy.

  16. 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.

  17. 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.

  18. Stock index dynamics worldwide: a comparative analysis

    NASA Astrophysics Data System (ADS)

    Cortines, A. A. G.; Anteneodo, C.; Riera, R.

    2008-09-01

    We perform a comparative analysis of twenty-four daily stock indices across the world, encompassing developed and emerging markets. We compute, directly from the return empirical time series, the Kramers-Moyal (KM) expansion coefficients that govern the evolution of the probability density function of returns throughout timelags. Our study discloses universal patterns of the KM coefficients, which can be described in terms of a few microscopic parameters. These parameters allow to quantify features such as deviations from Gaussianity or from efficiency, providing a tool to discriminate market dynamics.

  19. Analysis of sea ice dynamics

    NASA Technical Reports Server (NTRS)

    Zwally, J.

    1988-01-01

    The ongoing work has established the basis for using multiyear sea ice concentrations from SMMR passive microwave for studies of largescale advection and convergence/divergence of the Arctic sea ice pack. Comparisons were made with numerical model simulations and buoy data showing qualitative agreement on daily to interannual time scales. Analysis of the 7-year SMMR data set shows significant interannual variations in the total area of multiyear ice. The scientific objective is to investigate the dynamics, mass balance, and interannual variability of the Arctic sea ice pack. The research emphasizes the direct application of sea ice parameters derived from passive microwave data (SMMR and SSMI) and collaborative studies using a sea ice dynamics model. The possible causes of observed interannual variations in the multiyear ice area are being examined. The relative effects of variations in the large scale advection and convergence/divergence within the ice pack on a regional and seasonal basis are investigated. The effects of anomolous atmospheric forcings are being examined, including the long-lived effects of synoptic events and monthly variations in the mean geostrophic winds. Estimates to be made will include the amount of new ice production within the ice pack during winter and the amount of ice exported from the pack.

  20. Application Analysis and Decision with Dynamic Analysis

    DTIC Science & Technology

    2014-12-01

    analysis functionality. This will allow A2D to run an application in a controlled, virtual environment, and interact with it in ways similar to a human...extension. This new functionality installs and launches the application on 1 of several virtual machines (VMs) that sit on top of a simulation of a...standard network. The application will not be capable of reaching the wider Internet. As it runs, A2D will interact with the virtual phone and perform

  1. 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.

  2. 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

  3. Vehicle systems: coupled and interactive dynamics analysis

    NASA Astrophysics Data System (ADS)

    Vantsevich, Vladimir V.

    2014-11-01

    This article formulates a new direction in vehicle dynamics, described as coupled and interactive vehicle system dynamics. Formalised procedures and analysis of case studies are presented. An analytical consideration, which explains the physics of coupled system dynamics and its consequences for dynamics of a vehicle, is given for several sets of systems including: (i) driveline and suspension of a 6×6 truck, (ii) a brake mechanism and a limited slip differential of a drive axle and (iii) a 4×4 vehicle steering system and driveline system. The article introduces a formal procedure to turn coupled system dynamics into interactive dynamics of systems. A new research direction in interactive dynamics of an active steering and a hybrid-electric power transmitting unit is presented and analysed to control power distribution between the drive axles of a 4×4 vehicle. A control strategy integrates energy efficiency and lateral dynamics by decoupling dynamics of the two systems thus forming their interactive dynamics.

  4. 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.

  5. Dynamics Analysis of Wind Energy Production Development

    NASA Astrophysics Data System (ADS)

    Berg, V. I.; Zakirzakov, A. G.; Gordievskaya, E. F.

    2017-01-01

    The paper presents the analysis of the introduction experience and dynamics development of the world wind energy production. Calculated the amount of wind energy sources investments and the production capacity growth dynamics of the wind turbines. The studies have shown that the introduction dynamics of new wind energy sources is higher than any other energy source.

  6. Dynamic liquid-liquid-solid microextraction based on molecularly imprinted polymer filaments on-line coupling to high performance liquid chromatography for direct analysis of estrogens in complex samples.

    PubMed

    Zhong, Qisheng; Hu, Yufei; Hu, Yuling; Li, Gongke

    2012-06-08

    A novel sample preparation technique termed dynamic liquid-liquid-solid microextraction (DLLSME) was developed and on-line coupled to high performance liquid chromatography (HPLC) for direct extraction, desorption, and analysis of trace estrogens in complex samples. The DLLSME consists of the aqueous donor phase, the organic medium phase and the molecularly imprinted polymer filaments (MIPFs) as solid acceptor phase. The organic solvent with lesser density was directly added on top of the aqueous sample, and the dynamic extraction was performed by circulating the organic solvent through the MIPFs inserted into a PEEK tube which served as an extraction and desorption chamber. Afterwards, the extracted analytes on the MIPFs were on-line desorbed and then introduced into the HPLC for analysis. To evaluate the feasibility of the on-line system, a new DLLSME-HPLC method was developed for the analysis of five estrogens in aqueous samples by using 17β-estradiol MIPFs as the solid phase. Under the optimized conditions, the enrichment factors of 51-70, limits of detection of 0.08-0.25 μg/L and precision within 4.5-6.9% were achieved. Furthermore, the proposed method was applied to the analysis of real samples including urine, milk and skin toner, satisfactory recovery (81.9-99.8%) and reproducibility (4.1-7.9%) were obtained. Especially, 0.59 μg/L of 17β-estradiol was determined in female urine sample. The DLLSME offers an attractive alternative for direct analysis of trace analytes in aqueous samples and could potentially be extended to other adsorptive materials.

  7. Fluid Dynamics of High Performance Turbomachines.

    DTIC Science & Technology

    1987-12-01

    reflecting bound- ary conditions can be constructed. For the potential equation this was first done by Verdon et al [7] in 1975, and it is now the...for Time-Dependent Hyperbolic Systems. Center for Large Scale Scientific Computation CLaSSiC-87-16, Stanford University, Feb 1987. [7] J. M. Verdon ...Computational Fluid Dynamics Lab- oratory, 1986. [12] G. B. Whitham. Linear and Nonlinear Waves. John Wiley & Sons, 1974. [13] J. Mathews and R. L. Walker

  8. Generalized neural networks for spectral analysis: dynamics and Liapunov functions.

    PubMed

    Vegas, José M; Zufiria, Pedro J

    2004-03-01

    This paper analyzes local and global behavior of several dynamical systems which generalize some artificial neural network (ANN) semilinear models originally designed for principal component analysis (PCA) in the characterization of random vectors. These systems implicitly performed the spectral analysis of correlation (i.e. symmetric positive definite) matrices. Here, the proposed generalizations cover both nonsymmetric matrices as well as fully nonlinear models. Local stability analysis is performed via linearization and global behavior is analyzed by constructing several Liapunov functions.

  9. 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.

  10. 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.

  11. Computational stability analysis of dynamical systems

    NASA Astrophysics Data System (ADS)

    Nikishkov, Yuri Gennadievich

    2000-10-01

    Due to increased available computer power, the analysis of nonlinear flexible multi-body systems, fixed-wing aircraft and rotary-wing vehicles is relying on increasingly complex, large scale models. An important aspect of the dynamic response of flexible multi-body systems is the potential presence of instabilities. Stability analysis is typically performed on simplified models with the smallest number of degrees of freedom required to capture the physical phenomena that cause the instability. The system stability boundaries are then evaluated using the characteristic exponent method or Floquet theory for systems with constant or periodic coefficients, respectively. As the number of degrees of freedom used to represent the system increases, these methods become increasingly cumbersome, and quickly unmanageable. In this work, a novel approach is proposed, the Implicit Floquet Analysis, which evaluates the largest eigenvalues of the transition matrix using the Arnoldi algorithm, without the explicit computation of this matrix. This method is far more computationally efficient than the classical approach and is ideally suited for systems involving a large number of degrees of freedom. The proposed approach is conveniently implemented as a postprocessing step to any existing simulation tool. The application of the method to a geometrically nonlinear multi-body dynamics code is presented. This work also focuses on the implementation of trimming algorithms and the development of tools for the graphical representation of numerical simulations and stability information for multi-body systems.

  12. 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.

  13. 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...

  14. 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

  15. 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.

  16. Analysing the temporal dynamics of model performance for hydrological models

    NASA Astrophysics Data System (ADS)

    Reusser, D. E.; Blume, T.; Schaefli, B.; Zehe, E.

    2009-07-01

    The temporal dynamics of hydrological model performance gives insights into errors that cannot be obtained from global performance measures assigning a single number to the fit of a simulated time series to an observed reference series. These errors can include errors in data, model parameters, or model structure. Dealing with a set of performance measures evaluated at a high temporal resolution implies analyzing and interpreting a high dimensional data set. This paper presents a method for such a hydrological model performance assessment with a high temporal resolution and illustrates its application for two very different rainfall-runoff modeling case studies. The first is the Wilde Weisseritz case study, a headwater catchment in the eastern Ore Mountains, simulated with the conceptual model WaSiM-ETH. The second is the Malalcahuello case study, a headwater catchment in the Chilean Andes, simulated with the physics-based model Catflow. The proposed time-resolved performance assessment starts with the computation of a large set of classically used performance measures for a moving window. The key of the developed approach is a data-reduction method based on self-organizing maps (SOMs) and cluster analysis to classify the high-dimensional performance matrix. Synthetic peak errors are used to interpret the resulting error classes. The final outcome of the proposed method is a time series of the occurrence of dominant error types. For the two case studies analyzed here, 6 such error types have been identified. They show clear temporal patterns, which can lead to the identification of model structural errors.

  17. Analysing the temporal dynamics of model performance for hydrological models

    NASA Astrophysics Data System (ADS)

    Reusser, D. E.; Blume, T.; Schaefli, B.; Zehe, E.

    2008-11-01

    The temporal dynamics of hydrological model performance gives insights into errors that cannot be obtained from global performance measures assigning a single number to the fit of a simulated time series to an observed reference series. These errors can include errors in data, model parameters, or model structure. Dealing with a set of performance measures evaluated at a high temporal resolution implies analyzing and interpreting a high dimensional data set. This paper presents a method for such a hydrological model performance assessment with a high temporal resolution and illustrates its application for two very different rainfall-runoff modeling case studies. The first is the Wilde Weisseritz case study, a headwater catchment in the eastern Ore Mountains, simulated with the conceptual model WaSiM-ETH. The second is the Malalcahuello case study, a headwater catchment in the Chilean Andes, simulated with the physics-based model Catflow. The proposed time-resolved performance assessment starts with the computation of a large set of classically used performance measures for a moving window. The key of the developed approach is a data-reduction method based on self-organizing maps (SOMs) and cluster analysis to classify the high-dimensional performance matrix. Synthetic peak errors are used to interpret the resulting error classes. The final outcome of the proposed method is a time series of the occurrence of dominant error types. For the two case studies analyzed here, 6 such error types have been identified. They show clear temporal patterns which can lead to the identification of model structural errors.

  18. Performance Analysis of Surfing: A Review.

    PubMed

    Farley, Oliver R L; Abbiss, Chris R; Sheppard, Jeremy M

    2017-01-01

    Farley, ORL, Abbiss, CR, and Sheppard, JM. Performance Analysis of Surfing: A Review. J Strength Cond Res 31(1): 260-271, 2017-Despite the increased professionalism and substantial growth of surfing worldwide, there is limited information available to practitioners and coaches in terms of key performance analytics that are common in other field-based sports. Indeed, research analyzing surfing performance is limited to a few studies examining male surfers' heart rates, surfing activities through time-motion analysis (TMA) using video recordings and Global Positioning Satellite (GPS) data during competition and recreational surfing. These studies have indicated that specific activities undertaken during surfing are unique with a variety of activities (i.e., paddling, resting, wave riding, breath holding, and recovery of surfboard in the surf). Furthermore, environmental and wave conditions also seem to influence the physical demands of competition surfing. It is due to these demands that surfers are required to have a high cardiorespiratory fitness, high muscular endurance, and considerable strength and anaerobic power, particular within the upper torso. By exploring various methods of performance analysis used within other sports, it is possible to improve our understanding of surfing demands. In so doing this will assist in the development of protocols and strategies to assess physiological characteristics of surfers, monitor athlete performance, improve training prescription, and identify talent. Therefore, this review explores the current literature to provide insights into methodological protocols, delimitations of research into athlete analysis and an overview of surfing dynamics. Specifically, this review will describe and review the use of TMA, GPS, and other technologies (i.e., HR) that are used in external and internal load monitoring as they pertain to surfing.

  19. Angular-compliant hydrodynamic bearing performance under dynamic loads

    NASA Astrophysics Data System (ADS)

    Harnoy, A.; Rachoor, H.

    1993-07-01

    The study is focused on a dynamically loaded composite bearing, consisting of a hydrodynamic journal bearing inside the internal race of a rolling-element bearing. In this combination, the hydrodynamic bearing has an angular-compliant sleeve with a restricted freedom of rotation around its axis. Under static loads, the improvement is primarily in a significant reduction of friction and wear during the starting and stopping. Under periodical loads, our analysis shows that the performance depends on two dimensionless design parameters. Below particular critical values of these parameters, the results show a considerable improvement, demonstrated by a reduction of the maximum eccentricity. However, above the critical values, the bearing becomes unstable. These results indicate the significance of incorporating this computer assisted computation for each design.

  20. 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.

  1. 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

  2. Performance characterization of the dynamic programming obstacle detection algorithm.

    PubMed

    Gandhi, Tarak; Yang, Mau-Tsuen; Kasturi, Rangachar; Camps, Octavia I; Coraor, Lee D; McCandless, Jeffrey

    2006-05-01

    A computer vision-based system using images from an airborne aircraft can increase flight safety by aiding the pilot to detect obstacles in the flight path so as to avoid mid-air collisions. Such a system fits naturally with the development of an external vision system proposed by NASA for use in high-speed civil transport aircraft with limited cockpit visibility. The detection techniques should provide high detection probability for obstacles that can vary from subpixels to a few pixels in size, while maintaining a low false alarm probability in the presence of noise and severe background clutter. Furthermore, the detection algorithms must be able to report such obstacles in a timely fashion, imposing severe constraints on their execution time. For this purpose, we have implemented a number of algorithms to detect airborne obstacles using image sequences obtained from a camera mounted on an aircraft. This paper describes the methodology used for characterizing the performance of the dynamic programming obstacle detection algorithm and its special cases. The experimental results were obtained using several types of image sequences, with simulated and real backgrounds. The approximate performance of the algorithm is also theoretically derived using principles of statistical analysis in terms of the signal-to-noise ration (SNR) required for the probabilities of false alarms and misdetections to be lower than prespecified values. The theoretical and experimental performance are compared in terms of the required SNR.

  3. 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.

  4. 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.

  5. 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.

  6. 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…

  7. 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.

  8. 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.

  9. Mathematical analysis of vortex dynamics

    NASA Astrophysics Data System (ADS)

    Caflisch, Russel E.

    This review paper discusses the mathematical theory of vortex dynamics for incompressible, inviscid flow in two and three dimensions. The surveyed results include existence and uniqueness of time-dependent solutions, instability and singularity formation, convergence of numerical methods, and existence and stability of steady states. A simple integral formulation for the evolution of a three dimensional vortex sheet and a variational principle for the Batchelor flow problem are presented.

  10. 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.

  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. 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.

  13. 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.

  14. Contextual analysis framework for bursty dynamics

    NASA Astrophysics Data System (ADS)

    Jo, Hang-Hyun; Pan, Raj Kumar; Perotti, Juan I.; Kaski, Kimmo

    2013-06-01

    To understand the origin of bursty dynamics in natural and social processes we provide a general analysis framework in which the temporal process is decomposed into subprocesses and then the bursts in subprocesses, called contextual bursts, are combined to collective bursts in the original process. For the combination of subprocesses, it is required to consider the distribution of different contexts over the original process. Based on minimal assumptions for interevent time statistics, we present a theoretical analysis for the relationship between contextual and collective interevent time distributions. Our analysis framework helps to exploit contextual information available in decomposable bursty dynamics.

  15. 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.

  16. 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.

  17. Intentional thought dynamics during exercise performed until volitional exhaustion.

    PubMed

    Balagué, Natàlia; Hristovski, Robert; Garcia, Sergi; Aragonés, Daniel; Razon, Selen; Tenenbaum, Gershon

    2015-01-01

    Using a non-linear approach, intentional dynamics of thoughts were examined during constant cycling performed until volitional exhaustion. Participants (n = 12) completed two sessions at 80% Wmax. Their (1) intrinsic thought dynamics (i.e., no-imposed thoughts condition) and (2) intentional thought dynamics (i.e., imposed task-unrelated thoughts condition; TUT) were recorded and then classified into four categories: internal and external TUT (TUT-I, TUT-E) and external and internal task-related thoughts (TRT-E, TRT-I). The probability estimates for maintaining each thought category stable, the rate of switching from one category to another, and the entropy dynamics along the testing procedure were assessed and compared through time phase. Friedman ANOVA tests revealed a significant effect of effort increase on thought contents only in the imposed TUT test. While TUT-I probabilities decreased significantly (P < .001) as effort increased, TRT-I probabilities increased (P < .05). Moreover, the entropy to the entire thought dynamics increased at the outset of task performance and decreased upon approaching volitional exhaustion (P < .001). As time spent in constant effort increased, and volitional exhaustion approached, task relatedness (TUT, TRT), direction (internal, external), and entropy of thought contents changed unintentionally providing further evidence for a nonlinear dynamics of attention focus.

  18. 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.

  19. 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.

  20. 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.

  1. Dynamic analysis of grinding using the population balance model

    SciTech Connect

    Williams, M.C. |

    1995-12-31

    The dynamic behavior of batch mill, CSTR mill, and a closed grinding network consisting of a mill, sump, and cyclone was analyzed using the dynamic population balance model (PBM). The dynamic solution of the PBM of a batch, CSTR and a closed grinding network consisting of a mill, sump, and cyclone forms the basis of the dynamic analysis presented here. Two numerical dynamic solution approaches were used. These are: (1) providing additional constraints on breakage selection functions or (2) performing the Arbiter-Bhrany (or other) normalization of the selection functions. Actual experimental anthracite batch grinding data was used to obtain the functionality of the batch dynamic mill selection and breakage functions for a real physical system. The Levenberg-Marquardt algorithm for systems of constrained non-linear equations is used to solve the batch dynamic PBM grinding equations to obtain the grinding selection and breakage rate functions. The mill, sump and hydrocyclone were modeled as a CSTR operating at various retention times. Batch dynamic PBM data was used to provide the mill kinetic and breakage selection function data. Different dynamic solutions were obtained depending on the numerical approach used. Each solution approach to a dynamic PBM with transport, while giving the same prediction for a single batch grinding time, gives different solutions or predictions for mill composition for other grinding times. This fact makes dynamic nodal analysis and control problematic. The fact that the constraint solution approach gives a solution may suggest that normalization for closed networks is not necessary. Differences in solutions to the PBM cannot be excused away by inaccuracies in the data used to model the grinding phenomenon.

  2. 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

  3. Dynamic simulation models and performance of an OTEC power plant

    SciTech Connect

    Wormley, D.N.; Carmichael, D.A.; Umans, S.

    1983-08-01

    In this study, the aspects of plant performance which influence the potential for integration of an OTEC plant into a utility grid are considered. A set of simulation models have been developed for the evaluation of OTEC dynamic plant performance. A detailed nonlinear dynamic model has been forumlated which is useful for the assessment of component performance including heat exchangers, turbines, pumps and control systems. A reduced order linear model has been developed which is useful for studies of plant stability, control system development and transient performance of the plant connected to a utility grid. This model is particularly suitable for transient dynamic studies of an OTEC plant as a unit in a utility grid. A quasi-steady power availability model has also been developed which is useful to determine plant ouput power as a function of ocean thermal gradients so that the influence of daily and seasonal temperature variations may be easily computed. The study has found no fundamental technical barriers which would prohibit the interconnection of an OTEC plant into a utility grid. It has also shown that detailed consideration of turbine nozzle angle control is merited and such a control has the potential to provide superior performance in comparison to turbine bypass valve control.

  4. The role of ecological dynamics in analysing performance in team sports.

    PubMed

    Vilar, Luís; Araújo, Duarte; Davids, Keith; Button, Chris

    2012-01-01

    Performance analysis is a subdiscipline of sports sciences and one-approach, notational analysis, has been used to objectively audit and describe behaviours of performers during different subphases of play, providing additional information for practitioners to improve future sports performance. Recent criticisms of these methods have suggested the need for a sound theoretical rationale to explain performance behaviours, not just describe them. The aim of this article was to show how ecological dynamics provides a valid theoretical explanation of performance in team sports by explaining the formation of successful and unsuccessful patterns of play, based on symmetry-breaking processes emerging from functional interactions between players and the performance environment. We offer the view that ecological dynamics is an upgrade to more operational methods of performance analysis that merely document statistics of competitive performance. In support of our arguments, we refer to exemplar data on competitive performance in team sports that have revealed functional interpersonal interactions between attackers and defenders, based on variations in the spatial positioning of performers relative to each other in critical performance areas, such as the scoring zones. Implications of this perspective are also considered for practice task design and sport development programmes.

  5. Conformational analysis of oligosaccharides and polysaccharides using molecular dynamics simulations.

    PubMed

    Frank, Martin

    2015-01-01

    Complex carbohydrates usually have a large number of rotatable bonds and consequently a large number of theoretically possible conformations can be generated (combinatorial explosion). The application of systematic search methods for conformational analysis of carbohydrates is therefore limited to disaccharides and trisaccharides in a routine analysis. An alternative approach is to use Monte-Carlo methods or (high-temperature) molecular dynamics (MD) simulations to explore the conformational space of complex carbohydrates. This chapter describes how to use MD simulation data to perform a conformational analysis (conformational maps, hydrogen bonds) of oligosaccharides and how to build realistic 3D structures of large polysaccharides using Conformational Analysis Tools (CAT).

  6. Model Performance Evaluation and Scenario Analysis (MPESA)

    EPA Pesticide Factsheets

    Model Performance Evaluation and Scenario Analysis (MPESA) assesses the performance with which models predict time series data. The tool was developed Hydrological Simulation Program-Fortran (HSPF) and the Stormwater Management Model (SWMM)

  7. 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.

  8. A Dynamical Analysis of Sea Breeze Hodograph Rotation on Sardinia

    NASA Astrophysics Data System (ADS)

    Moisseeva, Nadya; Steyn, Douw

    2014-05-01

    We investigate the dynamics of diurnal sea-breeze rotation over coastal Sardinia using realistic and idealized model runs and historical observations. 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. WRF accurately captures the sea breeze circulation on all coasts, as depicted in station data. 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 of similar dimensions and latitude to Sardinia, but with dramatically simplified topography. Dynamical analysis of the idealized runs 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.

  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. Dynamic test/analysis correlation using reduced analytical models

    NASA Technical Reports Server (NTRS)

    Mcgowan, Paul E.; Angelucci, A. F.; Javeed, Mehzad

    1992-01-01

    Test/analysis correlation is an important aspect of the verification of analysis models which are used to predict on-orbit response characteristics of large space structures. This paper presents results of a study using reduced analysis models for performing dynamic test/analysis correlation. The reduced test-analysis model (TAM) has the same number and orientation of DOF as the test measurements. Two reduction methods, static (Guyan) reduction and the Improved Reduced System reduction, are applied to the test/analysis correlation of a laboratory truss structure. Simulated test results and modal test data are used to examine the performance of each method. It is shown that selection of DOF to be retained in the TAM is critical when large structural masses are involved. In addition, the use of modal test results may provide difficulties in TAM accuracy even if a large number of DOF are retained in the TAM.

  11. Dynamic test/analysis correlation using reduced analytical models

    NASA Technical Reports Server (NTRS)

    Mcgowan, Paul E.; Angelucci, A. Filippo; Javeed, Mehzad

    1992-01-01

    Test/analysis correlation is an important aspect of the verification of analysis models which are used to predict on-orbit response characteristics of large space structures. This paper presents results of a study using reduced analysis models for performing dynamic test/analysis correlation. The reduced test-analysis model (TAM) has the same number and orientation of DOF as the test measurements. Two reduction methods, static (Guyan) reduction and the Improved Reduced System (IRS) reduction, are applied to the test/analysis correlation of a laboratory truss structure. Simulated test results and modal test data are used to examine the performance of each method. It is shown that selection of DOF to be retained in the TAM is critical when large structural masses are involved. In addition, the use of modal test results may provide difficulties in TAM accuracy even if a large number of DOF are retained in the TAM.

  12. 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.

  13. Fluid Dynamic Analysis of Volcanic Tremor,

    DTIC Science & Technology

    1982-10-01

    stations near Mount Etna and concluded abrupt flow input, an abrupt outflow, or some other that the origin was source related, perturbation of an...the pressure head in meters, of the fluid transient theory to the analysis of tremor Q = the volumetric flow rate (m3/s), at Mount Etna . Analysis of...analytical potential of the fluid dynamic theory, we consider a single-phase fluid, a melt of Mount Hood andesite at 1250C, in which significant pressure

  14. SWECS tower dynamics analysis methods and results

    NASA Technical Reports Server (NTRS)

    Wright, A. D.; Sexton, J. H.; Butterfield, C. P.; Thresher, R. M.

    1981-01-01

    Several different tower dynamics analysis methods and computer codes were used to determine the natural frequencies and mode shapes of both guyed and freestanding wind turbine towers. These analysis methods are described and the results for two types of towers, a guyed tower and a freestanding tower, are shown. The advantages and disadvantages in the use of and the accuracy of each method are also described.

  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. Experimental investigations of fluid dynamic and thermal performance of nanofluids

    NASA Astrophysics Data System (ADS)

    Kulkarni, Devdatta Prakash

    The goal of this research was to investigate the fluid dynamic and thermal performance of various nanofluids. Nanofluids are dispersions of metallic nanometer size particles (<100 nm) into the base fluids. The choice of base fluid is an ethylene or propylene glycol and water mixture in cold regions. Initially the rheological characterization of copper oxide (CuO) nanofluids in water and in propylene glycol was performed. Results revealed that higher concentrations of CuO nanoparticles (5 to 15%) in water exhibited time-independent pseudoplastic and shear-thinning behavior. Lower concentrations (1 to 6%) of CuO nanofluids in propylene glycol revealed that these nanofluids behaved as Newtonian fluids. Both nanofluids showed that viscosity decreased exponentially with increase in temperature. Subsequent correlations for viscosities as a function of volume concentration and temperature were developed. Effects of different thermophysical properties on the Prandtl number of CuO, silicon dioxide (SiO2) and aluminum oxide (A12O 3) nanofluids were investigated. Results showed that the Prandtl number increased with increasing volume concentrations, which in turn increased the heat transfer coefficients of the nanofluids. Various nanofluids were compared for their heat transfer rates based on the Mouromtseff number, which is a Figure of Merit for heat transfer fluids. From this analysis, the optimal concentrations of nanoparticles in base fluids were found for CuO-water nanofluids. Experiments were performed to investigate the convective heat transfer enhancement and pressure loss of CuO, SiO2 and A12O 3 nanofluids in the turbulent regime. The increases in heat transfer coefficient by nanofluids for various volume concentrations compared to the base fluid were determined. Pressure loss was observed to increase with nanoparticle volume concentration. It was observed that an increase in particle diameter increased the heat transfer coefficient. Calculations showed that

  17. 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

  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. 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.

  20. Evaluation of bio-inspired morphing concepts with regard to aircraft dynamics and performance

    NASA Astrophysics Data System (ADS)

    Wickenheiser, Adam M.; Garcia, Ephrahim; Waszak, Martin

    2004-07-01

    This paper will discuss the application of various bio-inspired morphing concepts to unmanned aerial vehicle (UAV) designs. Several analysis tools will be introduced to calculate the aerodynamic benefits, dynamic response, and mission-level benefits of morphing shape changes. Empirical relations are employed to calculate the effects of various geometry changes on the aerodynamics of the vehicle. A six-degree-of-freedom simulation will evaluate the stability and dynamic response of each vehicle configuration as well as "snapshots" of the morphing change. Subsequently, an aircraft performance analysis will be conducted for various shape configurations. Specifically, the performance of a bio-inspired wing is compared to conventional designs. The aircraft dynamic improvements that morphing technologies introduce will be discussed.

  1. 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.

  2. Dynamic analysis of spur gears using computer program DANST

    NASA Astrophysics Data System (ADS)

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

    1993-06-01

    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.

  3. 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.

  4. Dynamic analysis of spur gears using computer program DANST

    SciTech Connect

    Oswald, F.B.; Lin, H.H.; Liou, Chuenheui; Valco, M.J.

    1993-06-01

    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. 14 refs.

  5. Dynamic Connectivity at Rest Predicts Attention Task Performance

    PubMed Central

    Askren, Mary K.; Boord, Peter; Grabowski, Thomas J.

    2015-01-01

    Abstract Consistent spatial patterns of coherent activity, representing large-scale networks, have been reliably identified in multiple populations. Most often, these studies have examined “stationary” connectivity. However, there is a growing recognition that there is a wealth of information in the time-varying dynamics of networks which has neural underpinnings, which changes with age and disease and that supports behavior. Using factor analysis of overlapping sliding windows across 25 participants with Parkinson disease (PD) and 21 controls (ages 41–86), we identify factors describing the covarying correlations of regions (dynamic connectivity) within attention networks and the default mode network, during two baseline resting-state and task runs. Cortical regions that support attention networks are affected early in PD, motivating the potential utility of dynamic connectivity as a sensitive way to characterize physiological disruption to these networks. We show that measures of dynamic connectivity are more reliable than comparable measures of stationary connectivity. Factors in the dorsal attention network (DAN) and fronto-parietal task control network, obtained at rest, are consistently related to the alerting and orienting reaction time effects in the subsequent Attention Network Task. In addition, the same relationship between the same DAN factor and the alerting effect was present during tasks. Although reliable, dynamic connectivity was not invariant, and changes between factor scores across sessions were related to changes in accuracy. In summary, patterns of time-varying correlations among nodes in an intrinsic network have a stability that has functional relevance. PMID:25014419

  6. 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.

  7. Nonlinear dynamics and quantitative EEG analysis.

    PubMed

    Jansen, B H

    1996-01-01

    Quantitative, computerized electroencephalogram (EEG) analysis appears to be based on a phenomenological approach to EEG interpretation, and is primarily rooted in linear systems theory. A fundamentally different approach to computerized EEG analysis, however, is making its way into the laboratories. The basic idea, inspired by recent advances in the area of nonlinear dynamics and chaos theory, is to view an EEG as the output of a deterministic system of relatively simple complexity, but containing nonlinearities. This suggests that studying the geometrical dynamics of EEGs, and the development of neurophysiologically realistic models of EEG generation may produce more successful automated EEG analysis techniques than the classical, stochastic methods. A review of the fundamentals of chaos theory is provided. Evidence supporting the nonlinear dynamics paradigm to EEG interpretation is presented, and the kind of new information that can be extracted from the EEG is discussed. A case is made that a nonlinear dynamic systems viewpoint to EEG generation will profoundly affect the way EEG interpretation is currently done.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

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

    SciTech Connect

    Xu, Dongping

    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.

  13. Expert performance in sport and the dynamics of talent development.

    PubMed

    Phillips, Elissa; Davids, Keith; Renshaw, Ian; Portus, Marc

    2010-04-01

    Research on expertise, talent identification and development has tended to be mono-disciplinary, typically adopting genocentric or environmentalist positions, with an overriding focus on operational issues. In this paper, the validity of dualist positions on sport expertise is evaluated. It is argued that, to advance understanding of expertise and talent development, a shift towards a multidisciplinary and integrative science focus is necessary, along with the development of a comprehensive multidisciplinary theoretical rationale. Here we elucidate dynamical systems theory as a multidisciplinary theoretical rationale for capturing how multiple interacting constraints can shape the development of expert performers. This approach suggests that talent development programmes should eschew the notion of common optimal performance models, emphasize the individual nature of pathways to expertise, and identify the range of interacting constraints that impinge on performance potential of individual athletes, rather than evaluating current performance on physical tests referenced to group norms.

  14. Echo Ranging/Probe Alert Performance Analysis.

    DTIC Science & Technology

    1982-11-04

    contract included technical analyses of acoustic communication equipment, system performance predictions, sea test design and data analysis, and...proposing functional system design alternatives. 2.0 SUMMARY OF WORK PERFORMED The JAYCOR effort focused on the analysis of the Echo Ranging/ Probe Alert...JAYCOR Document No. J640-020-82-2242, 16 August 1982, CONFIDENTIAL. 13. Probe Alert Design System Performance Estimates (U), J.L. Collins, JAYCOR Document

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Hierarchical Goal Analysis of Dynamic Decision Making in Microworld Experiments

    DTIC Science & Technology

    2009-03-01

    Hierarchical Goal Analysis of dynamic decision making in microworld experiments Vlad Zotov Renee Chow Defence R& D Canada Technical Memorandum DRDC...7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Defence R& D Canada - Toronto,1133 Sheppard Avenue West,PO Box 2000,Toronto, Ontario, Canada M3M...Defence R& D Canada – Toronto Technical Memorandum DRDC Toronto TM 2008-211 March 2009 Principal Author

  3. 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.

  4. Dynamic Thermal Management for High-Performance Storage Systems

    SciTech Connect

    Kim, Youngjae; Gurumurthi, Dr Sudhanva; Sivasubramaniam, Anand

    2012-01-01

    Thermal-aware design of disk drives is important because high temperatures can cause reliability problems. Dynamic Thermal Management (DTM) techniques have been proposed to operate the disk at the average case temperature, rather than at the worse case by modulating the activities to avoid thermal emergencies. The thermal emergencies can be caused by unexpected events, such as fan-breaks, increased inlet air temperature, etc. One of the DTM techniques is a delay-based approach that adjusts the disk seek activities, cooling down the disk drives. Even if such a DTM approach could overcome thermal emergencies without stopping disk activity, it suffers from long delays when servicing the requests. Thus, in this chapter, we investigate the possibility of using a multispeed disk-drive (called dynamic rotations per minute (DRPM)) that dynamically modulates the rotational speed of the platter for implementing the DTM technique. Using a detailed performance and thermal simulator of a storage system, we evaluate two possible DTM policies (- time-based and watermark-based) with a DRPM disk-drive and observe that dynamic RPM modulation is effective in avoiding thermal emergencies. However, we find that the time taken to transition between different rotational speeds of the disk is critical for the effectiveness of the DRPM based DTM techniques.

  5. 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.

  6. 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.

  7. Functional holography analysis: Simplifying the complexity of dynamical networks

    NASA Astrophysics Data System (ADS)

    Baruchi, Itay; Grossman, Danny; Volman, Vladislav; Shein, Mark; Hunter, John; Towle, Vernon L.; Ben-Jacob, Eshel

    2006-03-01

    We present a novel functional holography (FH) analysis devised to study the dynamics of task-performing dynamical networks. The latter term refers to networks composed of dynamical systems or elements, like gene networks or neural networks. The new approach is based on the realization that task-performing networks follow some underlying principles that are reflected in their activity. Therefore, the analysis is designed to decipher the existence of simple causal motives that are expected to be embedded in the observed complex activity of the networks under study. First we evaluate the matrix of similarities (correlations) between the activities of the network's components. We then perform collective normalization of the similarities (or affinity transformation) to construct a matrix of functional correlations. Using dimension reduction algorithms on the affinity matrix, the matrix is projected onto a principal three-dimensional space of the leading eigenvectors computed by the algorithm. To retrieve back information that is lost in the dimension reduction, we connect the nodes by colored lines that represent the level of the similarities to construct a holographic network in the principal space. Next we calculate the activity propagation in the network (temporal ordering) using different methods like temporal center of mass and cross correlations. The causal information is superimposed on the holographic network by coloring the nodes locations according to the temporal ordering of their activities. First, we illustrate the analysis for simple, artificially constructed examples. Then we demonstrate that by applying the FH analysis to modeled and real neural networks as well as recorded brain activity, hidden causal manifolds with simple yet characteristic geometrical and topological features are deciphered in the complex activity. The term "functional holography" is used to indicate that the goal of the analysis is to extract the maximum amount of functional

  8. Dynamic analysis of dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Xu, Bai-Xiang; Mueller, Ralf; Theis, Anika; Klassen, Markus; Gross, Dietmar

    2012-03-01

    An analytical model is proposed for the dynamic analysis of a homogeneously deformed dielectric elastomer actuator (DEA) with a standard sandwich structure. The equation of motion for the DEA is obtained by the Euler-Lagrange equation. Numerical results of the model are presented to show the vibration and oscillation behaviour of the system. Resonance phenomenon and damping effects are investigated. Results are discussed in comparison with those of the related topics in the literature.

  9. Methodologies for launcher-payload coupled dynamic analysis

    NASA Astrophysics Data System (ADS)

    Fransen, S. H. J. A.

    2012-06-01

    An important step in the design and verification process of spacecraft structures is the coupled dynamic analysis with the launch vehicle in the low-frequency domain, also referred to as coupled loads analysis (CLA). The objective of such analyses is the computation of the dynamic environment of the spacecraft (payload) in terms of interface accelerations, interface forces, center of gravity (CoG) accelerations as well as the internal state of stress. In order to perform an efficient, fast and accurate launcher-payload coupled dynamic analysis, various methodologies have been applied and developed. The methods are related to substructuring techniques, data recovery techniques, the effects of prestress and fluids and time integration problems. The aim of this paper was to give an overview of these methodologies and to show why, how and where these techniques can be used in the process of launcher-payload coupled dynamic analysis. In addition, it will be shown how these methodologies fit together in a library of procedures which can be used with the MSC.Nastran™ solution sequences.

  10. 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.

  11. 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.

  12. 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.

  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. Sustaining high performance: dynamic balancing in an otherwise unbalanced system.

    PubMed

    Wolf, Jason A

    2011-01-01

    As Ovid said, "There is nothing in the whole world which is permanent." It is this very premise that frames the discoveries in this chapter and the compelling paradox it has raised. What began as a question of how performance is sustained, unveiled a collection of core organizational paradoxes. The findings ultimately suggest that sustained high performance is not a permanent state an organization achieves, but rather it is through perpetual movement and dynamic balance that sustainability occurs. The idea of sustainability as movement is predicated on the ability of organizational members to move beyond the experience of paradox as an impediment to progress. Through holding three critical "movements"--agile/consistency, collective/individualism, and informative/inquiry--not as paradoxical, but as active polarities, the organizations in the study were able to transcend paradox, and take active steps to continuous achievement in outperforming their peers. The study, focused on a collection of hospitals across the Unites States, reveals powerful stories of care and service, of the profound grace of human capacity, and of clear actions taken to create significant results. All of this was achieved in an environment of great volatility, in essence an unbalanced system. It was the discovery of movement and ultimately of dynamic balancing that allowed the organizations to in this study to move beyond stasis to the continuous "state" of sustaining high performance.

  15. 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.

  16. Dynamic Analysis of a Spur Gear by the Dynamic Stiffness Method

    NASA Astrophysics Data System (ADS)

    HUANG, K. J.; LIU, T. S.

    2000-07-01

    This study treats a spur gear tooth as a variable cross-section Timoshenko beam to construct a dynamic model, being able to obtain transient response for spur gears of involute profiles. The dynamic responses of a single tooth and a gear pair are investigated. Firstly, polynomials are used to represent the gear blank and the tooth profile. The dynamic stiffness matrix and natural frequencies of the gear are in turn calculated. The forced response of a tooth subject to a shaft-driven transmission torque is calculated by performing modal analysis. This study takes into account time-varying stiffness and mass matrices and the gear meshing forces at moving meshing points. The forced response at arbitrary points in a gear tooth can be obtained. Calculation results of fillet stresses and strains are compared with those in the literature to verify the proposed method.

  17. 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.

  18. Effects of ADC Nonlinearity on the Spurious Dynamic Range Performance of Compressed Sensing

    PubMed Central

    Tian, Pengwu; Yu, Hongyi

    2014-01-01

    Analog-to-information converter (AIC) plays an important role in the compressed sensing system; it has the potential to significantly extend the capabilities of conventional analog-to-digital converter. This paper evaluates the impact of AIC nonlinearity on the dynamic performance in practical compressed sensing system, which included the nonlinearity introduced by quantization as well as the circuit non-ideality. It presents intuitive yet quantitative insights into the harmonics of quantization output of AIC, and the effect of other AIC nonlinearity on the spurious dynamic range (SFDR) performance is also analyzed. The analysis and simulation results demonstrated that, compared with conventional ADC-based system, the measurement process decorrelates the input signal and the quantization error and alleviate the effect of other decorrelates of AIC, which results in a dramatic increase in spurious free dynamic range (SFDR). PMID:24895645

  19. 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.

  20. Architecture Analysis of High Performance Capacitors (POSTPRINT)

    DTIC Science & Technology

    2009-07-01

    includes the measurement of heat dissipated from a recently developed fluorenyl polyester (FPE) capacitor under an AC excitation. II. Capacitor ...AFRL-RZ-WP-TP-2010-2100 ARCHITECTURE ANALYSIS OF HIGH PERFORMANCE CAPACITORS (POSTPRINT) Hiroyuki Kosai and Tyler Bixel UES, Inc...2009 4. TITLE AND SUBTITLE ARCHITECTURE ANALYSIS OF HIGH PERFORMANCE CAPACITORS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c

  1. 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

  2. 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.

  3. 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.

  4. Nonlinear Dynamic Analysis of Scalp EEG Epileptic Signals

    NASA Astrophysics Data System (ADS)

    Blanco, Susana A.; Creso, Judith; Figliola, Alejandra; Quiroga, Rodrigo Quian; Rosso, Osvaldo A.

    Noisy signals obtained during a tonic-clonic epileptic seizure, are usually neglected for visual inspection by the physicians due to the presence of muscle artifacts. Although noise obscures completely the recording, information about the underlying brain activity can be obtained by filtering, through the Orthogonal Wavelet Transforms, those frequencies bands associated with muscle activity. After generating a "noise free" signal by removing the muscle artifacts with wavelets, a dynamical analysis of the brain behavior will be performed by using nonlinear dynamics methods. The values for nonlinear metric invariants, like the correlation dimension and the maximum Lyapunov exponent, confirm that the brain dynamical behavior is more ordered during the epileptic seizure than pre-seizure stage.

  5. 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.

  6. 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).

  7. Dynamic analysis and control of novel moving mass flight vehicle

    NASA Astrophysics Data System (ADS)

    Li, Jianqing; Gao, Changsheng; Jing, Wuxing; Wei, Pengxin

    2017-02-01

    In terms of the moving mass control technology, the configuration of internal moving masses is a key challenge. In order to reduce the complexity of configuring these moving masses in a flight vehicle, a combination bank-to-turn control mode with the single moving mass and reaction jet is proposed in this paper. To investigate the dynamics and the potential of the control mechanism, an attitude dynamic model with single moving mass is generated. The dynamic analysis indicates that the control stability, control authority and dynamic behavior of the pitch channel are determined by the mass ratio of the moving mass to the system and the difference between the mass center of the moving mass and the mass center of the vehicle body. Interestingly, control authority increases proportionally with increasing mass ratio and also with decreasing the magnitude of the static margin. To deal with the coupling caused by the additional inertia moment which is generated by the motion of the moving mass, an adaptive control law by using dynamic inversion theory and the extended state observer is designed. Also, a compensator is designed for eliminating the influence of the servo actuator's dynamics on attitude of the flight vehicle. Finally, the simulation results validate the quality of the proposed adaptive controller which ensures a good performance in the novel configuration with internal moving mass.

  8. Higher order SVD analysis for dynamic texture synthesis.

    PubMed

    Costantini, Roberto; Sbaiz, Luciano; Süsstrunk, Sabine

    2008-01-01

    Videos representing flames, water, smoke, etc., are often defined as dynamic textures: "textures" because they are characterized by the redundant repetition of a pattern and "dynamic" because this repetition is also in time and not only in space. Dynamic textures have been modeled as linear dynamic systems by unfolding the video frames into column vectors and describing their trajectory as time evolves. After the projection of the vectors onto a lower dimensional space by a singular value decomposition (SVD), the trajectory is modeled using system identification techniques. Synthesis is obtained by driving the system with random noise. In this paper, we show that the standard SVD can be replaced by a higher order SVD (HOSVD), originally known as Tucker decomposition. HOSVD decomposes the dynamic texture as a multidimensional signal (tensor) without unfolding the video frames on column vectors. This is a more natural and flexible decomposition, since it permits us to perform dimension reduction in the spatial, temporal, and chromatic domain, while standard SVD allows for temporal reduction only. We show that for a comparable synthesis quality, the HOSVD approach requires, on average, five times less parameters than the standard SVD approach. The analysis part is more expensive, but the synthesis has the same cost as existing algorithms. Our technique is, thus, well suited to dynamic texture synthesis on devices limited by memory and computational power, such as PDAs or mobile phones.

  9. A waved journal bearing concept with improved steady-state and dynamic performance

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin

    1994-01-01

    Analysis of the waved journal bearing concept featuring a waved inner bearing diameter for use with a compressible lubricant (gas) is presented. A three wave, waved journal bearing geometry is used to show the geometry of this concept. The performance of generic waved bearings having either three, four, six, or eight waves is predicted for air lubricated bearings. Steady-state performance is discussed in terms of bearing load capacity, while the dynamic performance is discussed in terms of dynamic coefficients and fluid film stability. It was found that the bearing wave amplitude has an important influence on both steady-state and dynamic performance of the waved journal bearing. For a fixed eccentricity ratio, the bearing steady-state load capacity and direct dynamic stiffness coefficient increase as the wave amplitude increases. Also, the waved bearing becomes more stable as the wave amplitude increases. In addition, increasing the number of waves reduces the waved bearing's sensitivity to the direction of the applied load relative to the wave. However, the range in which the bearing performance can be varied decreases as the number of waves increases. Therefore, both the number and the amplitude of the waves must be properly selected to optimize the waved bearing design for a specific application. It is concluded that the stiffness of an air bearing, due to the hydrodynamic effect, could be doubled and made to run stably by using a six or eight wave geometry with a wave amplitude approximately half of the bearing radial clearance.

  10. Analysis of Performance Variation Using Query Expansion.

    ERIC Educational Resources Information Center

    Alemayehu, Nega

    2003-01-01

    Discussion of information retrieval performance evaluation focuses on a case study using a statistical repeated measures analysis of variance for testing the significance of factors, such as retrieval method and topic in retrieval performance variation. Analyses of the effect of query expansion on document ranking confirm that expansion affects…

  11. 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)

  12. Structural dynamic analysis of composite beams

    NASA Astrophysics Data System (ADS)

    Suresh, J. K.; Venkatesan, C.; Ramamurti, V.

    1990-12-01

    In the treatment of the structural dynamic problem of composite materials, two alternate types of formulations, based on the elastic modulus and compliance quantities, exist in the literature. The definitions of the various rigidities are observed to differ in these two approaches. Following these two types of formulation, the structural dynamic characteristics of a composite beam are analyzed. The results of the analysis are compared with those available in the literature. Based on the comparison, the influence of the warping function in defining the coupling terms in the modulus approach and also on the natural frequencies of the beam has been identified. It is found from the analysis that, in certain cases, the difference between the results of the two approaches is appreciable. These differences may be attributed to the constraints imposed on the deformation and flexibility of the beam by the choice of the description of the warping behaviour. Finally, the influence of material properties on the structural dynamic characteristics of the beam is studied for different composites for various angles of orthotropy.

  13. A new technique for dynamic analysis of bladder compliance.

    PubMed

    Gilmour, R F; Churchill, B M; Steckler, R E; Houle, A M; Khoury, A E; McLorie, G A

    1993-10-01

    We propose an alternative method of measuring compliance that takes into account the multiple phases of bladder filling. We describe our new technique, dynamic compliance analysis, and evaluate its clinical applicability. To perform the analysis we digitized a cystometrogram curve at a sampling rate of 2 samples per second using an MS-DOS computer system. A program designed to retrieve the stored data was used to analyze the subtracted bladder pressure. The result yielded a value of compliance every half second that was then plotted on an x-y graph, with instantaneous compliance as the dependent variable and per cent of total volume infused as the independent variable. To determine the clinical applicability of this technique we chose 63 curves from clinically normal patients. The results of the dynamic compliance analyses were predictable. The dynamic compliance values for the normal group had a minimum that was always greater than 10 ml./cm. water throughout the tonus limb (phase 2) of the cystometrogram. We conclude that dynamic compliance analysis yields more information about bladder response during filling, similar to the stress-strain curve used in the study of solid mechanics.

  14. 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.

  15. EMTP modeling of IGBT dynamic performance for power dissipation estimation

    SciTech Connect

    Wong, C.

    1995-12-31

    A new approach to the modeling of IGBTs (Insulated Gate Bipolar Transistors) for EMTP (ElectroMagnetic Transients Program) simulation is developed. Other commercially available simulators, such a PSPICE, model the devices on an exact semiconductor physics basis. They suffer from large amount of CPU time for sinewave PWM inverter applications which require a complete cycle simulation at fundamental frequency with a small time step to cover the details of IGBT switching transients. This approach uses a curve-fitting method, combined with the point-by-point user-defined function available in EMTP, to model the dynamic characteristics of IGBTs. Since there is no device physics modeling required, the simulation is much faster than the conventional approach. The proposed method is applicable for both static and dynamic modeling, on a cycle-by-cycle basis, which is important for dynamical power dissipation and thermal analysis. The simulation includes IGBT turn-on and turn-off transients, IGBT saturation, free-wheeling diode forward voltage and reverse recovery characteristics. The simulation results are verified by comparison with the experimental measured data. Measurements show a close agreement with simulations.

  16. Framing of task performance strategies: effects on performance in a multiattribute dynamic decision making environment.

    PubMed

    Nygren, T E

    1997-09-01

    It is well documented that the way a static choice task is "framed" can dramatically alter choice behavior, often leading to observable preference reversals. This framing effect appears to result from perceived changes in the nature or location of a person's initial reference point, but it is not clear how framing effects might generalize to performance on dynamic decision making tasks that are characterized by high workload, time constraints, risk, or stress. A study was conducted to examine the hypothesis that framing can introduce affective components to the decision making process and can influence, either favorably (positive frame) or adversely (negative frame), the implementation and use of decision making strategies in dynamic high-workload environments. Results indicated that negative frame participants were significantly impaired in developing and employing a simple optimal decision strategy relative to a positive frame group. Discussion focuses on implications of these results for models of dynamic decision making.

  17. 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.

  18. 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.

  19. The effects of training on performance and performance-related states in individual elite athletes: a dynamic approach.

    PubMed

    Barnett, Anthony; Cerin, Ester; Reaburn, Peter; Hooper, Sue

    2010-08-01

    There are difficulties undertaking controlled training studies with elite athletes. Thus, data from non-elite performers are often presented in scientific journals and subsequently used to guide general training principles. This information may not be transferable or specific enough to inform training practices in an individual elite athlete. However, the nature of athletic participation at elite levels provides the opportunity to collect training data, performance-related variables, and performance data of elite athletes over long periods. In this paper, we describe how dynamic linear models provide an opportunity to use these data to inform training. Data from an elite female triathlete collected over a 111-day training period were used to model the relationship between training and self-reported fatigue. The dynamic linear model analysis showed the independent effects of the three modes of triathlon training on fatigue, how these can change across time, and the possible influence of other unmeasured variables. This paper shows the potential for the use of dynamic linear models as an aid to planning training in elite athletes.

  20. Dynamic competitive probabilistic principal components analysis.

    PubMed

    López-Rubio, Ezequiel; Ortiz-DE-Lazcano-Lobato, Juan Miguel

    2009-04-01

    We present a new neural model which extends the classical competitive learning (CL) by performing a Probabilistic Principal Components Analysis (PPCA) at each neuron. The model also has the ability to learn the number of basis vectors required to represent the principal directions of each cluster, so it overcomes a drawback of most local PCA models, where the dimensionality of a cluster must be fixed a priori. Experimental results are presented to show the performance of the network with multispectral image data.

  1. Massive Contingency Analysis with High Performance Computing

    SciTech Connect

    Huang, Zhenyu; Chen, Yousu; Nieplocha, Jaroslaw

    2009-07-26

    Contingency analysis is a key function in the Energy Management System (EMS) to assess the impact of various combinations of power system component failures based on state estimates. Contingency analysis is also extensively used in power market operation for feasibility test of market solutions. Faster analysis of more cases is required to safely and reliably operate today’s power grids with less marginal and more intermittent renewable energy sources. Enabled by the latest development in the computer industry, high performance computing holds the promise of meet the need in the power industry. This paper investigates the potential of high performance computing for massive contingency analysis. The framework of "N-x" contingency analysis is established and computational load balancing schemes are studied and implemented with high performance computers. Case studies of massive 300,000-contingency-case analysis using the Western Electricity Coordinating Council power grid model are presented to illustrate the application of high performance computing and demonstrate the performance of the framework and computational load balancing schemes.

  2. 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.

  3. POWER GRID DYNAMICS: ENHANCING POWER SYSTEM OPERATION THROUGH PRONY ANALYSIS

    SciTech Connect

    Ray, C.; Huang, Z.

    2007-01-01

    Prony Analysis is a technique used to decompose a signal into a series consisting of weighted complex exponentials and promises to be an effi cient way of recognizing sensitive lines during faults in power systems such as the U.S. Power grid. Positive Sequence Load Flow (PSLF) was used to simulate the performance of a simple two-area-four-generator system and the reaction of the system during a line fault. The Dynamic System Identifi cation (DSI) Toolbox was used to perform Prony analysis and use modal information to identify key transmission lines for power fl ow adjustment to improve system damping. The success of the application of Prony analysis methods to the data obtained from PSLF is reported, and the key transmission line for adjustment is identifi ed. Future work will focus on larger systems and improving the current algorithms to deal with networks such as large portions of the Western Electricity Coordinating Council (WECC) power grid.

  4. Musical structure analysis using similarity matrix and dynamic programming

    NASA Astrophysics Data System (ADS)

    Shiu, Yu; Jeong, Hong; Kuo, C.-C. Jay

    2005-10-01

    Automatic music segmentation and structure analysis from audio waveforms based on a three-level hierarchy is examined in this research, where the three-level hierarchy includes notes, measures and parts. The pitch class profile (PCP) feature is first extracted at the note level. Then, a similarity matrix is constructed at the measure level, where a dynamic time warping (DTW) technique is used to enhance the similarity computation by taking the temporal distortion of similar audio segments into account. By processing the similarity matrix, we can obtain a coarse-grain music segmentation result. Finally, dynamic programming is applied to the coarse-grain segments so that a song can be decomposed into several major parts such as intro, verse, chorus, bridge and outro. The performance of the proposed music structure analysis system is demonstrated for pop and rock music.

  5. 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.

  6. Interactive computer code for dynamic and soil structure interaction analysis

    SciTech Connect

    Mulliken, J.S.

    1995-12-01

    A new interactive computer code is presented in this paper for dynamic and soil-structure interaction (SSI) analyses. The computer program FETA (Finite Element Transient Analysis) is a self contained interactive graphics environment for IBM-PC`s that is used for the development of structural and soil models as well as post-processing dynamic analysis output. Full 3-D isometric views of the soil-structure system, animation of displacements, frequency and time domain responses at nodes, and response spectra are all graphically available simply by pointing and clicking with a mouse. FETA`s finite element solver performs 2-D and 3-D frequency and time domain soil-structure interaction analyses. The solver can be directly accessed from the graphical interface on a PC, or run on a number of other computer platforms.

  7. 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.

  8. 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.

  9. 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.

  10. Shuttle/TDRSS communications system performance analysis

    NASA Technical Reports Server (NTRS)

    Braun, W. R.

    1980-01-01

    The results of the performance analysis performed on the Shuttle/Tracking and Data Relay Satellite System (TDRSS) communications system are presented. The existing Shuttle/TDRSS link simulation program were modified and refined to model the post-radio frequency interference TDRS hardware and to evaluate the performance degradation due to RFI effects. The refined link models were then used to determine, evaluate and assess expected S-band and Ku-band link performance. Parameterization results are presented for the ground station carrier and timing recovery circuits

  11. 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.

  12. Performance comparison between static and dynamic cardiac CT on perfusion quantitation and patient classification tasks

    NASA Astrophysics Data System (ADS)

    Bindschadler, Michael; Modgil, Dimple; Branch, Kelley R.; La Riviere, Patrick J.; Alessio, Adam M.

    2015-03-01

    Cardiac CT acquisitions for perfusion assessment can be performed in a dynamic or static mode. In this simulation study, we evaluate the relative classification and quantification performance of these modes for assessing myocardial blood flow (MBF). In the dynamic method, a series of low dose cardiac CT acquisitions yields data on contrast bolus dynamics over time; these data are fit with a model to give a quantitative MBF estimate. In the static method, a single CT acquisition is obtained, and the relative CT numbers in the myocardium are used to infer perfusion states. The static method does not directly yield a quantitative estimate of MBF, but these estimates can be roughly approximated by introducing assumed linear relationships between CT number and MBF, consistent with the ways such images are typically visually interpreted. Data obtained by either method may be used for a variety of clinical tasks, including 1) stratifying patients into differing categories of ischemia and 2) using the quantitative MBF estimate directly to evaluate ischemic disease severity. Through simulations, we evaluate the performance on each of these tasks. The dynamic method has very low bias in MBF estimates, making it particularly suitable for quantitative estimation. At matched radiation dose levels, ROC analysis demonstrated that the static method, with its high bias but generally lower variance, has superior performance in stratifying patients, especially for larger patients.

  13. HL-20 computational fluid dynamics analysis

    NASA Astrophysics Data System (ADS)

    Weilmuenster, K. James; Greene, Francis A.

    1993-09-01

    The essential elements of a computational fluid dynamics analysis of the HL-20/personnel launch system aerothermal environment at hypersonic speeds including surface definition, grid generation, solution techniques, and visual representation of results are presented. Examples of solution technique validation through comparison with data from ground-based facilities are presented, along with results from computations at flight conditions. Computations at flight points indicate that real-gas effects have little or no effect on vehicle aerodynamics and, at these conditions, results from approximate techniques for determining surface heating are comparable with those obtained from Navier-Stokes solutions.

  14. HL-20 computational fluid dynamics analysis

    NASA Technical Reports Server (NTRS)

    Weilmuenster, K. J.; Greene, Francis A.

    1993-01-01

    The essential elements of a computational fluid dynamics analysis of the HL-20/personnel launch system aerothermal environment at hypersonic speeds including surface definition, grid generation, solution techniques, and visual representation of results are presented. Examples of solution technique validation through comparison with data from ground-based facilities are presented, along with results from computations at flight conditions. Computations at flight points indicate that real-gas effects have little or no effect on vehicle aerodynamics and, at these conditions, results from approximate techniques for determining surface heating are comparable with those obtained from Navier-Stokes solutions.

  15. 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.

  16. The relationship between lower-body stiffness and dynamic performance.

    PubMed

    Pruyn, Elizabeth C; Watsford, Mark; Murphy, Aron

    2014-10-01

    Greater levels of lower-body stiffness have been associated with improved outcomes for a number of physical performance variables involving rapid stretch-shorten cycles. The aim of this study was to investigate the relationship between several measures of lower-body stiffness and physical performance variables typically evident during team sports in female athletes. Eighteen female athletes were assessed for quasi-static stiffness (myometry) for several isolated muscles in lying and standing positions. The muscles included the medial gastrocnemius (MedGast), lateral gastrocnemius, soleus, and Achilles tendon. Dynamic stiffness during unilateral hopping was also assessed. Participants were separated into relatively stiff and compliant groups for each variable. A number of significant differences in performance were evident between stiff and compliant subjects. When considering the quasi-static stiffness of the MedGast in lying and standing positions, relatively stiff participants recorded significantly superior results during agility, bounding, sprinting, and jumping activities. Stiffness as assessed by hopping did not discriminate between performance ability in any test. Relationships highlighted by MedGast results were supported by further significant differences in eccentric utilisation ratio and drop jump results between stiff and compliant groups for the lateral gastrocnemius and soleus in lying and standing positions. Higher levels of lower-body stiffness appear to be advantageous for females when performing rapid and (or) repeated stretch-shorten cycle movements, including sprinting, bounding, and jumping. Further, the stiffness of the MedGast is of particular importance during the performance of these activities. It is important for practitioners working with athletes in sports that rely upon these activities for success to consider stiffness assessment and modification.

  17. 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.

  18. 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.

  19. Dynamic Factor Analysis Models with Time-Varying Parameters

    ERIC Educational Resources Information Center

    Chow, Sy-Miin; Zu, Jiyun; Shifren, Kim; Zhang, Guangjian

    2011-01-01

    Dynamic factor analysis models with time-varying parameters offer a valuable tool for evaluating multivariate time series data with time-varying dynamics and/or measurement properties. We use the Dynamic Model of Activation proposed by Zautra and colleagues (Zautra, Potter, & Reich, 1997) as a motivating example to construct a dynamic factor…

  20. Dynamic Factor Analysis Models With Time-Varying Parameters.

    PubMed

    Chow, Sy-Miin; Zu, Jiyun; Shifren, Kim; Zhang, Guangjian

    2011-04-11

    Dynamic factor analysis models with time-varying parameters offer a valuable tool for evaluating multivariate time series data with time-varying dynamics and/or measurement properties. We use the Dynamic Model of Activation proposed by Zautra and colleagues (Zautra, Potter, & Reich, 1997) as a motivating example to construct a dynamic factor model with vector autoregressive relations and time-varying cross-regression parameters at the factor level. Using techniques drawn from the state-space literature, the model was fitted to a set of daily affect data (over 71 days) from 10 participants who had been diagnosed with Parkinson's disease. Our empirical results lend partial support and some potential refinement to the Dynamic Model of Activation with regard to how the time dependencies between positive and negative affects change over time. A simulation study is conducted to examine the performance of the proposed techniques when (a) changes in the time-varying parameters are represented using the true model of change, (b) supposedly time-invariant parameters are represented as time-varying, and

  1. Thermodynamic performance analysis of ramjet engine at wide working conditions

    NASA Astrophysics Data System (ADS)

    Ou, Min; Yan, Li; Tang, Jing-feng; Huang, Wei; Chen, Xiao-qian

    2017-03-01

    Although ramjet has the advantages of high-speed flying and higher specific impulse, the performance parameters will decline seriously with the increase of flight Mach number and flight height. Therefore, the investigation on the thermodynamic performance of ramjet is very crucial for broadening the working range. In the current study, a typical ramjet model has been employed to investigate the performance characteristics at wide working conditions. First of all, the compression characteristic analysis is carried out based on the Brayton cycle. The obtained results show that the specific cross-section area (A2 and A5) and the air-fuel ratio (f) have a great influence on the ramjet performance indexes. Secondly, the thermodynamic calculation process of ramjet is given from the view of the pneumatic thermal analysis. Then, the variable trends of the ramjet performance indexes with the flow conditions, the air-fuel ratio (f), the specific cross-sectional area (A2 and A5) under the fixed operating condition, equipotential dynamic pressure condition and variable dynamic pressure condition have been discussed. Finally, the optimum value of the specific cross-sectional area (A5) and the air-fuel ratio (f) of the ramjet model at a fixed work condition (Ma=3.5, H=12 km) are obtained.

  2. 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.

  3. 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.

  4. Performative family: homosexuality, marriage and intergenerational dynamics in China.

    PubMed

    Choi, Susanne Yp; Luo, Ming

    2016-06-01

    Using in-depth interview data on nominal marriages - legal marriages between a gay man and a lesbian to give the appearance of heterosexuality - this paper develops the concept of performative family to explain the processes through which parents and their adult children negotiate and resolve disagreements in relation to marriage decisions in post-socialist China. We identify three mechanisms - network pressure, a revised discourse of filial piety and resource leverage - through which parents influence their gay offspring's decision to turn to nominal marriage. We also delineate six strategies, namely minimizing network participation, changing expectations, making partial concessions, drawing the line, delaying decisions and ending the marriage, by which gay people in nominal marriages attempt to meet parental expectations while simultaneously retaining a degree of autonomy. Through these interactions, we argue that Chinese parents and their gay adult children implicitly and explicitly collaborate to perform family, emphasizing the importance of formally meeting society's expectations about marriage rather than substantively yielding to its demands. We also argue that the performative family is a pragmatic response to the tension between the persistent centrality of family and marriage and the rising tide of individualism in post-socialist China. We believe that our findings highlight the specific predicament of homosexual people. They also shed light on the more general dynamics of intergenerational negotiation because there is evidence that the mechanisms used by parents to exert influence may well be similar between gay and non-gay people.

  5. 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.

  6. 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

  7. High-performance holographic technologies for fluid-dynamics experiments

    PubMed Central

    Orlov, Sergei S.; Abarzhi, Snezhana I.; Oh, Se Baek; Barbastathis, George; Sreenivasan, Katepalli R.

    2010-01-01

    Modern technologies offer new opportunities for experimentalists in a variety of research areas of fluid dynamics. Improvements are now possible in the state-of-the-art in precision, dynamic range, reproducibility, motion-control accuracy, data-acquisition rate and information capacity. These improvements are required for understanding complex turbulent flows under realistic conditions, and for allowing unambiguous comparisons to be made with new theoretical approaches and large-scale numerical simulations. One of the new technologies is high-performance digital holography. State-of-the-art motion control, electronics and optical imaging allow for the realization of turbulent flows with very high Reynolds number (more than 107) on a relatively small laboratory scale, and quantification of their properties with high space–time resolutions and bandwidth. In-line digital holographic technology can provide complete three-dimensional mapping of the flow velocity and density fields at high data rates (over 1000 frames per second) over a relatively large spatial area with high spatial (1–10 μm) and temporal (better than a few nanoseconds) resolution, and can give accurate quantitative description of the fluid flows, including those of multi-phase and unsteady conditions. This technology can be applied in a variety of problems to study fundamental properties of flow–particle interactions, rotating flows, non-canonical boundary layers and Rayleigh–Taylor mixing. Some of these examples are discussed briefly. PMID:20211881

  8. Performance bounds for dynamic causal modeling of brain connectivity.

    PubMed

    Wu, Shun Chi; Swindlehurst, A Lee

    2012-01-01

    The use of complex dynamical models have been proposed for describing the connections and causal interactions between different regions of the brain. The goal of these models is to accurately mimic the event-related potentials observed by EEG/MEG measurement systems, and are useful in understanding overall brain functionality. In this paper, we focus on a class of nonlinear dynamic causal models (DCM) that are described by a set of connectivity parameters. In practice, the DCM parameters are inferred using data obtained by an EEG or MEG sensor array in response to a certain event or stimulus, and the resulting estimates are used to analyze the strength and direction of the causal interactions between different brain regions. The usefulness of the parameter estimates will depend on how accurately they can be estimated, which in turn will depend on noise, the sampling rate, number of data samples collected, the accuracy of the source localization and reconstruction steps, etc. The goal of this paper is to derive Cramér-Rao performance bounds for DCM estimates, and examine the behavior of the bounds under different operating conditions.

  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. 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.

  11. 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.

  12. 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

  13. Aero-Thermo-Dynamic Mass Analysis.

    PubMed

    Shiba, Kota; Yoshikawa, Genki

    2016-07-14

    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.

  14. 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.

  15. Adaptive control schemes for improving dynamic performance of efficiency-optimized induction motor drives.

    PubMed

    Kumar, Navneet; Raj Chelliah, Thanga; Srivastava, S P

    2015-07-01

    Model Based Control (MBC) is one of the energy optimal controllers used in vector-controlled Induction Motor (IM) for controlling the excitation of motor in accordance with torque and speed. MBC offers energy conservation especially at part-load operation, but it creates ripples in torque and speed during load transition, leading to poor dynamic performance of the drive. This study investigates the opportunity for improving dynamic performance of a three-phase IM operating with MBC and proposes three control schemes: (i) MBC with a low pass filter (ii) torque producing current (iqs) injection in the output of speed controller (iii) Variable Structure Speed Controller (VSSC). The pre and post operation of MBC during load transition is also analyzed. The dynamic performance of a 1-hp, three-phase squirrel-cage IM with mine-hoist load diagram is tested. Test results are provided for the conventional field-oriented (constant flux) control and MBC (adjustable excitation) with proposed schemes. The effectiveness of proposed schemes is also illustrated for parametric variations. The test results and subsequent analysis confer that the motor dynamics improves significantly with all three proposed schemes in terms of overshoot/undershoot peak amplitude of torque and DC link power in addition to energy saving during load transitions.

  16. Analysis of ultra-triathlon performances.

    PubMed

    Lepers, Romuald; Knechtle, Beat; Knechtle, Patrizia; Rosemann, Thomas

    2011-01-01

    Despite increased interest in ultra-endurance events, little research has examined ultra-triathlon performance. The aims of this study were: (i) to compare swimming, cycling, running, and overall performances in three ultra-distance triathlons, double Ironman distance triathlon (2IMT) (7.6 km swimming, 360 km cycling, and 84.4 km running), triple Ironman distance triathlon (3IMT) (11.4 km, 540 km, and 126.6 km), and deca Ironman distance triathlon (10IMT) (38 km, 1800 km, and 420 km) and (ii) to examine the relationships between the 2IMT, 3IMT, and 10IMT performances to create predicted equations of the 10IMT performances. Race results from 1985 through 2009 were examined to identify triathletes who performed the three considered ultra-distances. In total, 73 triathletes (68 men and 5 women) were identified. The contribution of swimming to overall ultra-triathlon performance was lower than for cycling and running. Running performance was more important to overall performance for 2IMT and 3IMT compared with 10IMT The 2IMT and 3IMT performances were significantly correlated with 10IMT performances for swimming and cycling, but not for running. 10IMT total time performance might be predicted by the following equation: 10IMT race time (minutes) = 5885 + 3.69 × 3IMT race time (minutes). This analysis of human performance during ultra-distance triathlons represents a unique data set in the field of ultra-endurance events. Additional studies are required to determine the physiological and psychological factors associated with ultra-triathlon performance.

  17. US U-25 channel performance analysis

    SciTech Connect

    Doss, E.; Pan, Y. C.

    1980-07-01

    The results of an ANL computational analysis of the performance of the US U-25 MHD channel are presented. This channel has gone through several revisions. The major revision occurred after it had been decided by the DOE Office of MHD to operate the channel with platinum-clad copper electrodes (cold), rather than with ceramic electrodes (hot), as originally planned. This work has been performed at the request of the DOE Office of MHD and the US U-25 generator design Review Committee. The channel specifications and operating conditions are presented. The combustor temperature and thermodynamic and electrical properties of the plasma are computed, and the results are discussed. The MHD channel performance has been predicted for different operating conditions. Sensitivity studies have also been performed on the effects of mass flow rate, surface roughness, combustor temperatures, and loading on the channel performance.

  18. Estimation of changes in dynamic hydraulic force in a magnetically suspended centrifugal blood pump with transient computational fluid dynamics analysis.

    PubMed

    Masuzawa, Toru; Ohta, Akiko; Tanaka, Nobuatu; Qian, Yi; Tsukiya, Tomonori

    2009-01-01

    The effect of the hydraulic force on magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926 376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 14 l/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1 N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump.

  19. Analytic Perturbation Analysis of Discrete Event Dynamic Systems

    SciTech Connect

    Uryasev, S.

    1994-09-01

    This paper considers a new Analytic Perturbation Analysis (APA) approach for Discrete Event Dynamic Systems (DEDS) with discontinuous sample-path functions with respect to control parameters. The performance functions for DEDS usually are formulated as mathematical expectations, which can be calculated only numerically. APA is based on new analytic formulas for the gradients of expectations of indicator functions; therefore, it is called an analytic perturbation analysis. The gradient of performance function may not coincide with the expectation of a gradient of sample-path function (i.e., the interchange formula for the gradient and expectation sign may not be valid). Estimates of gradients can be obtained with one simulation run of the models.

  20. Using Ratio Analysis to Evaluate Financial Performance.

    ERIC Educational Resources Information Center

    Minter, John; And Others

    1982-01-01

    The ways in which ratio analysis can help in long-range planning, budgeting, and asset management to strengthen financial performance and help avoid financial difficulties are explained. Types of ratios considered include balance sheet ratios, net operating ratios, and contribution and demand ratios. (MSE)

  1. A Waved Journal Bearing Concept-Evaluating Steady-State and Dynamic Performance with a Potential Active Control Alternative

    NASA Technical Reports Server (NTRS)

    Dimofte, Florin

    1993-01-01

    Analysis of the waved journal bearing concept featuring a waved inner bearing diameter for use with a compressible lubricant (gas) is presented. The performance of generic waved bearings having either three or four waves is predicted for air lubricated bearings. Steady-state performance is discussed in terms of bearing load capacity, while the dynamic performance is discussed in terms of fluid film stability and dynamic coefficients. It was found that the bearing wave amplitude has an important influence on both the steady-state and the dynamic performance of the waved journal bearing. For a fixed eccentricity ratio, the bearing steady-state load capacity and direct dynamic stiffness coefficient increase as the wave amplitude increases.

  2. Molecular Dynamics Simulations on High-Performance Reconfigurable Computing Systems.

    PubMed

    Chiu, Matt; Herbordt, Martin C

    2010-11-01

    The acceleration of molecular dynamics (MD) simulations using high-performance reconfigurable computing (HPRC) has been much studied. Given the intense competition from multicore and GPUs, there is now a question whether MD on HPRC can be competitive. We concentrate here on the MD kernel computation: determining the short-range force between particle pairs. In one part of the study, we systematically explore the design space of the force pipeline with respect to arithmetic algorithm, arithmetic mode, precision, and various other optimizations. We examine simplifications and find that some have little effect on simulation quality. In the other part, we present the first FPGA study of the filtering of particle pairs with nearly zero mutual force, a standard optimization in MD codes. There are several innovations, including a novel partitioning of the particle space, and new methods for filtering and mapping work onto the pipelines. As a consequence, highly efficient filtering can be implemented with only a small fraction of the FPGA's resources. Overall, we find that, for an Altera Stratix-III EP3ES260, 8 force pipelines running at nearly 200 MHz can fit on the FPGA, and that they can perform at 95% efficiency. This results in an 80-fold per core speed-up for the short-range force, which is likely to make FPGAs highly competitive for MD.

  3. Dynamic performance of an aero-assist spacecraft - AFE

    NASA Technical Reports Server (NTRS)

    Chang, Ho-Pen; French, Raymond A.

    1992-01-01

    Dynamic performance of the Aero-assist Flight Experiment (AFE) spacecraft was investigated using a high-fidelity 6-DOF simulation model. Baseline guidance logic, control logic, and a strapdown navigation system to be used on the AFE spacecraft are also modeled in the 6-DOF simulation. During the AFE mission, uncertainties in the environment and the spacecraft are described by an error space which includes both correlated and uncorrelated error sources. The principal error sources modeled in this study include navigation errors, initial state vector errors, atmospheric variations, aerodynamic uncertainties, center-of-gravity off-sets, and weight uncertainties. The impact of the perturbations on the spacecraft performance is investigated using Monte Carlo repetitive statistical techniques. During the Solid Rocket Motor (SRM) deorbit phase, a target flight path angle of -4.76 deg at entry interface (EI) offers very high probability of avoiding SRM casing skip-out from the atmosphere. Generally speaking, the baseline designs of the guidance, navigation, and control systems satisfy most of the science and mission requirements.

  4. Performance of HEPA filters under hot dynamic conditions

    SciTech Connect

    Frankum, D.P.; Costigan, G.

    1995-02-01

    Accidents in nuclear facilities involving fires may have implications upon the ventilation systems where high efficiency particulate air (HEPA) filters are used to minimise the airborne release of radioactive or toxic particles. The Filter Development Section at Harwell Laboratory has been investigating the effect of temperature on the performance of HEPA filters under hot dynamic conditions[{sub 1}] for a number of years. The test rig is capable of delivering air flows of 10001/s (at ambient conditions) at temperatures up to 500{degrees}C, where measurements of the penetration and pressure drop across the filter are obtained. This paper reports the experiments on different constructions of HEPA filters; rectangular and circular. The filters were tested at an air temperature of 200{degrees}C for up to 48 hours at the rated airflow to assess their performance. The penetration measurements for rectangular filters were observed to be below 0.021% after prolonged operation. In a number of cases, holes appeared along the pleat creases of circular filters although the penetration remained below 1%. The sealing gasket for these filters was noted to deform with temperature, permitting a leakage path. A prototype high strength circular filter was evaluated at temperatures of up to 400{degrees}C with a penetration less than 0.65%.

  5. Severe accident analysis using dynamic accident progression event trees

    NASA Astrophysics Data System (ADS)

    Hakobyan, Aram P.

    In present, the development and analysis of Accident Progression Event Trees (APETs) are performed in a manner that is computationally time consuming, difficult to reproduce and also can be phenomenologically inconsistent. One of the principal deficiencies lies in the static nature of conventional APETs. In the conventional event tree techniques, the sequence of events is pre-determined in a fixed order based on the expert judgments. The main objective of this PhD dissertation was to develop a software tool (ADAPT) for automated APET generation using the concept of dynamic event trees. As implied by the name, in dynamic event trees the order and timing of events are determined by the progression of the accident. The tool determines the branching times from a severe accident analysis code based on user specified criteria for branching. It assigns user specified probabilities to every branch, tracks the total branch probability, and truncates branches based on the given pruning/truncation rules to avoid an unmanageable number of scenarios. The function of a dynamic APET developed includes prediction of the conditions, timing, and location of containment failure or bypass leading to the release of radioactive material, and calculation of probabilities of those failures. Thus, scenarios that can potentially lead to early containment failure or bypass, such as through accident induced failure of steam generator tubes, are of particular interest. Also, the work is focused on treatment of uncertainties in severe accident phenomena such as creep rupture of major RCS components, hydrogen burn, containment failure, timing of power recovery, etc. Although the ADAPT methodology (Analysis of Dynamic Accident Progression Trees) could be applied to any severe accident analysis code, in this dissertation the approach is demonstrated by applying it to the MELCOR code [1]. A case study is presented involving station blackout with the loss of auxiliary feedwater system for a

  6. Probabilistic Analysis of Gas Turbine Field Performance

    NASA Technical Reports Server (NTRS)

    Gorla, Rama S. R.; Pai, Shantaram S.; Rusick, Jeffrey J.

    2002-01-01

    A gas turbine thermodynamic cycle was computationally simulated and probabilistically evaluated in view of the several uncertainties in the performance parameters, which are indices of gas turbine health. Cumulative distribution functions and sensitivity factors were computed for the overall thermal efficiency and net specific power output due to the thermodynamic random variables. These results can be used to quickly identify the most critical design variables in order to optimize the design, enhance performance, increase system availability and make it cost effective. The analysis leads to the selection of the appropriate measurements to be used in the gas turbine health determination and to the identification of both the most critical measurements and parameters. Probabilistic analysis aims at unifying and improving the control and health monitoring of gas turbine aero-engines by increasing the quality and quantity of information available about the engine's health and performance.

  7. The impact of interface bonding efficiency on high-burnup spent nuclear fuel dynamic performance

    SciTech Connect

    Jiang, Hao; Wang, Jy-An John; Wang, Hong

    2016-09-26

    Finite element analysis (FEA) was used to investigate the impact of interfacial bonding efficiency at pellet-pellet and pellet-clad interfaces of high-burnup (HBU) spent nuclear fuel (SNF) on system dynamic performance. Bending moments M were applied to FEA model to evaluate the system responses. From bending curvature, κ, flexural rigidity EI can be estimated as EI = M/κ. The FEA simulation results were benchmarked with experimental results from cyclic integrated reversal bending fatigue test (CIRFT) of HBR fuel rods. The consequence of interface debonding between fuel pellets and cladding is a redistribution of the loads carried by the fuel pellets to the clad, which results in a reduction in composite rod system flexural rigidity. Furthermore, the interface bonding efficiency at the pellet-pellet and pellet-clad interfaces can significantly dictate the SNF system dynamic performance. With the consideration of interface bonding efficiency, the HBU SNF fuel property was estimated with CIRFT test data.

  8. Canonical and symplectic analysis for three dimensional gravity without dynamics

    NASA Astrophysics Data System (ADS)

    Escalante, Alberto; Osmart Ochoa-Gutiérrez, H.

    2017-03-01

    In this paper a detailed Hamiltonian analysis of three-dimensional gravity without dynamics proposed by V. Hussain is performed. We report the complete structure of the constraints and the Dirac brackets are explicitly computed. In addition, the Faddeev-Jackiw symplectic approach is developed; we report the complete set of Faddeev-Jackiw constraints and the generalized brackets, then we show that the Dirac and the generalized Faddeev-Jackiw brackets coincide to each other. Finally, the similarities and advantages between Faddeev-Jackiw and Dirac's formalism are briefly discussed.

  9. Fluid Dynamic and Stability Analysis of a Thin Liquid Sheet

    NASA Technical Reports Server (NTRS)

    McMaster, Matthew S.

    1992-01-01

    Interest in thin sheet flows has recently been renewed due to their potential application in space radiators. Theoretical and experimental studies of the fluid dynamics and stability of thin liquid sheet flows have been carried out in this thesis. A computer program was developed to determine the cross-sectional shape of the edge cylinder given the cross-sectional area of the edge cylinder. A stability analysis was performed on a non-planer liquid sheet. A study was conducted to determine the effects of air resistance on the sheet.

  10. Dynamic analysis of the earth pole oscillation process

    NASA Astrophysics Data System (ADS)

    Filippova, A. S.

    2015-11-01

    In the framework of classical mechanics, we perform an amplitude-frequency analysis of a small-parameter model of the Earth pole diurnal oscillations under the action of luni-solar gravitational-tidal torques. The Euler-Liouville dynamic equations with irregular perturbations taken into account are used to obtain the structural properties of diurnal oscillations of the Earth pole coordinates. The results of the Earth pole motion simulation are compared with the high-precision data of VLBI observations on a short time interval.

  11. Centaur Standard Shroud (CSS) full jettison test dynamic analysis

    NASA Technical Reports Server (NTRS)

    Kasper, H. J.; Donovan, R. M.

    1974-01-01

    During the space power facility jettison tests, the non-domed half of the Centaur standard shroud was allowed to completely separate from its hinge connection and was caught in a horizontal catch net. A rigid body dynamic analysis that was performed to predict the half shroud prior to and after net contact is presented. Analytical predictions of the longitudinal and circumferential bending moments imposed on the half shroud by the catch net and the net pressure on the half shroud corrugated skin are also presented.

  12. Numerical model of solar dynamic radiator for parametric analysis

    NASA Technical Reports Server (NTRS)

    Rhatigan, Jennifer L.

    1989-01-01

    Growth power requirements for Space Station Freedom will be met through addition of 25 kW solar dynamic (SD) power modules. Extensive thermal and power cycle modeling capabilities have been developed which are powerful tools in Station design and analysis, but which prove cumbersome and costly for simple component preliminary design studies. In order to aid in refining the SD radiator to the mature design stage, a simple and flexible numerical model was developed. The model simulates heat transfer and fluid flow performance of the radiator and calculates area mass and impact survivability for many combinations of flow tube and panel configurations, fluid and material properties, and environmental and cycle variations.

  13. Dynamic Analysis of Mobile Device Applications

    SciTech Connect

    Corey Thuen

    2013-01-01

    The On-Device Dynamic Analysis of Mobile Applications (ODAMA) project was started in an effort to protect mobile devices used in Industrial Control Systems (ICS) from cyber attack. Because mobile devices hide as much of the “computer” as possible, the user’s ability to assess the software running on their system is limited. The research team chose Google’s Android platform for this initial research because it is open source and it would give us freedom in our approach, including the ability to modify the mobile device’s operating system itself. The research team concluded that a Privileged Application was the right approach, and the result was ODAMA. This project is an important piece of the work to secure the expanding use of mobile devices with our nation’s critical infrastructure.

  14. Dynamic mode decomposition analysis of detonation waves

    NASA Astrophysics Data System (ADS)

    Massa, L.; Kumar, R.; Ravindran, P.

    2012-06-01

    Dynamic mode decomposition is applied to study the self-excited fluctuations supported by transversely unstable detonations. The focus of this study is on the stability of the limit cycle solutions and their response to forcing. Floquet analysis of the unforced conditions reveals that the least stable perturbations are almost subharmonic with ratio between global mode and fundamental frequency λi/ωf = 0.47. This suggests the emergence of period doubling modes as the route to chaos observed in larger systems. The response to forcing is analyzed in terms of the coherency of the four fundamental energy modes: acoustic, entropic, kinetic, and chemical. Results of the modal decomposition suggest that the self-excited oscillations are quite insensitive to vortical forcing, and maintain their coherency up to a forcing turbulent Mach number of 0.3.

  15. Pharmaceutical applications of dynamic mechanical thermal analysis.

    PubMed

    Jones, David S; Tian, Yiwei; Abu-Diak, Osama; Andrews, Gavin P

    2012-04-01

    The successful development of polymeric drug delivery and biomedical devices requires a comprehensive understanding of the viscoleastic properties of polymers as these have been shown to directly affect clinical efficacy. Dynamic mechanical thermal analysis (DMTA) is an accessible and versatile analytical technique in which an oscillating stress or strain is applied to a sample as a function of oscillatory frequency and temperature. Through cyclic application of a non-destructive stress or strain, a comprehensive understanding of the viscoelastic properties of polymers may be obtained. In this review, we provide a concise overview of the theory of DMTA and the basic instrumental/operating principles. Moreover, the application of DMTA for the characterization of solid pharmaceutical and biomedical systems has been discussed in detail. In particular we have described the potential of DMTA to measure and understand relaxation transitions and miscibility in binary and higher-order systems and describe the more recent applications of the technique for this purpose.

  16. Performance analysis and prediction in triathlon.

    PubMed

    Ofoghi, Bahadorreza; Zeleznikow, John; Macmahon, Clare; Rehula, Jan; Dwyer, Dan B

    2016-01-01

    Performance in triathlon is dependent upon factors that include somatotype, physiological capacity, technical proficiency and race strategy. Given the multidisciplinary nature of triathlon and the interaction between each of the three race components, the identification of target split times that can be used to inform the design of training plans and race pacing strategies is a complex task. The present study uses machine learning techniques to analyse a large database of performances in Olympic distance triathlons (2008-2012). The analysis reveals patterns of performance in five components of triathlon (three race "legs" and two transitions) and the complex relationships between performance in each component and overall performance in a race. The results provide three perspectives on the relationship between performance in each component of triathlon and the final placing in a race. These perspectives allow the identification of target split times that are required to achieve a certain final place in a race and the opportunity to make evidence-based decisions about race tactics in order to optimise performance.

  17. Dynamic analysis and trajectory tracking of a tethered space robot

    NASA Astrophysics Data System (ADS)

    Soltani, Mehrzad; Keshmiri, Mehdi; Misra, Arun K.

    2016-11-01

    Dynamic analysis and trajectory tracking of a Tethered Space Robot (TSR) is investigated in this paper. A hybrid controller is used to perform the control task. It consists of two components, the first one deals with librational motion of the tether, while the second one takes care of the manipulator motion. A Nonlinear Model Predictive Control (NMPC) approach is used to control the tether libration; for this purpose, the libration is described by a single degree of freedom and the tether length rate is employed as the input to suppress the librational motion. A modified Computed Torque Method (CTM) is used to control the manipulator motion. The dynamic interaction between the manipulator motion and the librational motion is considered both in the system dynamics and control of the system. Using numerical simulations, performance of the proposed control system is evaluated for end-effector positioning as well as for trajectory tracking for two cases: a Low Earth Orbit (LEO) and the Geostationary Earth Orbit (GEO).

  18. Dynamic modelling and analysis of space webs

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Baoyin, HeXi; Li, JunFeng

    2011-04-01

    Future space missions demand operations on large flexible structures, for example, space webs, the lightweight cable nets deployable in space, which can serve as platforms for very large structures or be used to capture orbital objects. The interest in research on space webs is likely to increase in the future with the development of promising applications such as Furoshiki sat-ellite of JAXA, Robotic Geostationary Orbit Restorer (ROGER) of ESA and Grapple, Retrieve And Secure Payload (GRASP) of NASA. Unlike high-tensioned nets in civil engineering, space webs may be low-tensioned or tensionless, and extremely flexible, owing to the microgravity in the orbit and the lack of support components, which may cause computational difficulties. Mathematical models are necessary in the analysis of space webs, especially in the conceptual design and evaluation for prototypes. A full three-dimensional finite element (FE) model was developed in this work. Trivial truss elements were adopted to reduce the computational complexity. Considering cable is a compression-free material and its tensile stiffness is also variable, we introduced the cable material constitutive relationship to work out an accurate and feasible model for prototype analysis and design. In the static analysis, the stress distribution and global deformation of the webs were discussed to get access to the knowledge of strength of webs with different types of meshes. In the dynamic analysis, special attention was paid to the impact problem. The max stress and global deformation were investigated. The simulation results indicate the interesting phenomenon which may be worth further research.

  19. NPAC-Nozzle Performance Analysis Code

    NASA Technical Reports Server (NTRS)

    Barnhart, Paul J.

    1997-01-01

    A simple and accurate nozzle performance analysis methodology has been developed. The geometry modeling requirements are minimal and very flexible, thus allowing rapid design evaluations. The solution techniques accurately couple: continuity, momentum, energy, state, and other relations which permit fast and accurate calculations of nozzle gross thrust. The control volume and internal flow analyses are capable of accounting for the effects of: over/under expansion, flow divergence, wall friction, heat transfer, and mass addition/loss across surfaces. The results from the nozzle performance methodology are shown to be in excellent agreement with experimental data for a variety of nozzle designs over a range of operating conditions.

  20. Dynamic process analysis by moments of extreme orders

    NASA Astrophysics Data System (ADS)

    Šimberová, S.; Suk, T.

    2016-01-01

    Dynamic processes in astronomical observations are captured in various video sequences. The image datacubes are represented by the datasets of random variables. Diagnostics of a fast developing event is based on the specific behavior of the high-order moments (HOM) in time. The moment curves computed in an image video sequence give valuable information about various phases of the phenomenon and significant periods in the frequency analysis. The proposed method uses statistical moments of high and very high orders to describe and investigate the dynamic process in progress. Since these moments are highly correlated, the method of principal component analysis (PCA) has been suggested for following frequency analysis. PCA can be used both for decorrelation of the moments and for determination of the number of used moments. We experimentally illustrate performance of the method on simulated data. A typical development of the dynamic phenomenon is modeled by the moment time curve. Then applications to the real data sequences follow: solar active regions observed in the spectral line H α (wavelength 6563 A˚-Ondřejov and Kanzelhöhe observatories) in two different angular resolutions. The frequency analysis of the first few principal components showed common periods or quasi-periods of all examined events and the periods specific for individual events. The detailed analysis of the moment's methodology can contribute to the observational mode settings. The method can be applied to video sequences obtained by observing systems with various angular resolutions. It is robust to noise and it can work with high range of sampling frequencies.

  1. Translational and rotational dynamic analysis of a superconducting levitation system

    NASA Astrophysics Data System (ADS)

    Cansiz, A.; Hull, J. R.; Gundogdu, Ö.

    2005-07-01

    The rotational dynamics of a disc-shaped permanent magnet rotor levitated over a high temperature superconductor was studied experimentally and theoretically. The interaction between the rotor magnet and the superconductor was modelled by assuming the magnet to be a magnetic dipole and the superconductor a diamagnet. In the magnetomechanical analysis of the superconductor part, the frozen image concept was combined with the diamagnetic image, and the damping in the system was neglected. The interaction potential of the system is the combination of magnetic and gravitational potentials. From the dynamical analysis the equations of motion of the permanent magnet were stated as a function of lateral, vertical, tilt, precision and rotating angles. The vibration behaviour and correlation of the vibration of one direction with that of another were determined with a numerical calculation based on the Runge-Kutta method. The various vibrational frequencies identified were vertical, radial, tilt, precession and rotation. The tests performed for experimental verifications were translational and rotational. The permanent magnet was 'spun up' under vacuum conditions to analyse the dynamics of the free 'spin down' behaviour of the permanent magnet.

  2. Dynamic self-guiding analysis of Alzheimer's disease

    PubMed Central

    Kurakin, Alexei; Bredesen, Dale E.

    2015-01-01

    We applied a self-guiding evolutionary algorithm to initiate the synthesis of the Alzheimer's disease-related data and literature. A protein interaction network associated with amyloid-beta precursor protein (APP) and a seed model that treats Alzheimer's disease as progressive dysregulation of APP-associated signaling were used as dynamic “guides” and structural “filters” in the recursive search, analysis, and assimilation of data to drive the evolution of the seed model in size, detail, and complexity. Analysis of data and literature across sub-disciplines and system-scale discovery platforms suggests a key role of dynamic cytoskeletal connectivity in the stability, plasticity, and performance of multicellular networks and architectures. Chronic impairment and/or dysregulation of cell adhesions/synapses, cytoskeletal networks, and/or reversible epithelial-to-mesenchymal-like transitions, which enable and mediate the stable and coherent yet dynamic and reconfigurable multicellular architectures, may lead to the emergence and persistence of the disordered, wound-like pockets/microenvironments of chronically disconnected cells. Such wound-like microenvironments support and are supported by pro-inflammatory, pro-secretion, de-differentiated cellular phenotypes with altered metabolism and signaling. The co-evolution of wound-like microenvironments and their inhabitants may lead to the selection and stabilization of degenerated cellular phenotypes, via acquisition of epigenetic modifications and mutations, which eventually result in degenerative disorders such as cancer and Alzheimer's disease. PMID:26041885

  3. Analysis of Dynamic Stall Through Chirp Signal Pitch Excursions

    NASA Astrophysics Data System (ADS)

    Heintz, Kyle; Coleman, Dustin; Wicks, Michael; Corke, Thomas; Thomas, Flint

    2013-11-01

    An augmentation of the typical pitching airfoil experiment has been performed where the pitching frequency and amplitude are dynamically varied in a short-time event to produce a ``chirp'' trajectory, α (t) =α0 +α1 (t) sin (tω (t)) . The frequency evolution followed a Schroeder-phase relation, ω (t) =ωmin + K (ωmax -ωmin) . The frequencies ranged from 0.5 Hz to 30 Hz, resulting in reduced frequencies from 0.02 to 0.1. The free-stream Mach number ranged from Mach 0.4 to 0.6, giving chord Reynolds numbers from 5 ×105 to 3 ×106 . The airfoil was a NACA 23012 section shape that was fully instrumented with 31 flush-mounted high-bandwidth pressure transducers. The pressure transducer outputs were simultaneously sampled with the instantaneous angle of attack, α (t) . The motivation for this study was to compare dynamic stall under non-equilibrium conditions. A particular interest is on the flow features that occur when dynamically passing between light and deep stall regimes. The results include phase analysis of aerodynamic loads, wavelet-based spectral analysis, and the determination of the intra-cycle aerodynamic damping factors.

  4. Pattern dynamics analysis of seismic catalogs

    NASA Astrophysics Data System (ADS)

    Tiampo, K.; Rundle, J.; Klein, W.; McGinnis, S.; Posadas, A.; Fernàndez, J.; Luzòn, F.

    2003-04-01

    The historical earthquake record, while not complete, spans hundreds to thousands of years of human history. As a result, large, extended fault systems such as those in California are known to demonstrate complex space-time seismicity patterns, which include, but are not limited to, repetitive events, precursory activity and quiescence, and aftershock sequences ((Mogi, 1969; Keilis-Borok et al., 1980; Kanamori, 1981; Kagan and Jackson, 1992; Saleur et al., 1996; Ellsworth and Cole, 1997; Pollitz and Sacks, 1997; Bowman et al., 1998; Nanjo et al., 1998; Wyss and Wiemer, 1999). Although the characteristics of these patterns can be qualitatively described, a systematic quantitative analysis remains elusive (Kanamori, 1981; Turcotte, 1991; Geller et al., 1997). Here we describe a new technique, formulated based on new developments in the physical and theoretical understanding of these complex, nonlinear fault systems that isolates emergent regions of coherent, correlated seismicity (Bak and Tang, 1989; Rundle, 1989; Sornette and Sornette, 1989; Rundle and Klein, 1995; Sammis et al., 1996; 1997; Fisher et al., 1997; Jaume and Sykes, 1999; Rundle et al., 1999; Tiampo et al., 2002). Analysis of data taken prior to large events reveals that the appearance of the coherent correlated regions is often associated with the future occurrence of major earthquakes in the same areas or other tectonic mechanisms such as aseismic slip events (Tiampo et al., 2002). We proceed to detail this pattern dynamics methodology and then identify systematic space-time variations in the seismicity from several tectonic regions.

  5. Effects of dynamic and static stretching on vertical jump performance and electromyographic activity.

    PubMed

    Hough, Paul A; Ross, Emma Z; Howatson, Glyn

    2009-03-01

    The results of previous research have demonstrated that static stretching (SS) can reduce muscular performance and that dynamic stretching (DS) can enhance muscular performance. The purpose of this study was to assess the effects of SS and DS on vertical jump (VJ) performance and electromyographic (EMG) activity of the m. vastus medialis. Eleven healthy men (age 21 +/- 2 years) took part in 3 conditions (no stretching [NS], SS, and DS), on separate occasions in a randomized, crossover design. During each condition, measurements of VJ height and EMG activity during the VJ were recorded. A repeated-measures analysis of variance and post hoc analysis indicated that VJ height was significantly less (4.19 +/- 4.47%) after SS than NS (p < 0.05) and significantly greater (9.44 +/- 4.25%) in DS than SS (p < 0.05). There was significantly greater EMG amplitude in the DS compared with the SS (p < 0.05). The results demonstrated that SS has a negative influence on VJ performance, whereas DS has a positive impact. Increased VJ performance after DS may be attributed to postactivation potentiation, whereas the reduction in VJ performance after SS may be attributable to neurological impairment and a possible alteration in the viscoelastic properties of the muscular tendon unit (MTU). This investigation provides some physiological basis for the inclusion of DS and exclusion of SS in preparation for activities requiring jumping performance.

  6. Performance of a 10 Gbps FSO System Implementing Novel Beam Tracking a Dynamic Buffering Modem

    NASA Technical Reports Server (NTRS)

    Kiriazes, John; Valencia, J. Emilio; Peach, Robert; Visone, Chris; Burdge, Geoffrey; Vickers, John; Leclerc, Troy; Sauer, Paul; Andrews, Larry; Phillips, Ron

    2012-01-01

    A 10 Gbps Free space optical (FSO) system implements beam tracking, a high dynamic range optical receiver, and a dynamic buffering packet modem. Performance was characterized at the 4.5 km Shuttle Landing Facility at Kennedy Space Center Florida.

  7. Structural dynamic analysis of a ball joint

    NASA Astrophysics Data System (ADS)

    Hwang, Seok-Cheol; Lee, Kwon-Hee

    2012-11-01

    Ball joint is a rotating and swiveling element that is typically installed at the interface between two parts. In an automobile, the ball joint is the component that connects the control arms to the steering knuckle. The ball joint can also be installed in linkage systems for motion control applications. This paper describes the simulation strategy for a ball joint analysis, considering manufacturing process. Its manufacturing process can be divided into plugging and spinning. Then, the interested responses is selected as the stress distribution generated between its ball and bearing. In this paper, a commercial code of NX DAFUL using an implicit integration method is introduced to calculate the response. In addition, the gap analysis is performed to investigate the fitness, focusing on the response of the displacement of a ball stud. Also, the optimum design is suggested through case studies.

  8. Multiprocessor smalltalk: Implementation, performance, and analysis

    SciTech Connect

    Pallas, J.I.

    1990-01-01

    Multiprocessor Smalltalk demonstrates the value of object-oriented programming on a multiprocessor. Its implementation and analysis shed light on three areas: concurrent programming in an object oriented language without special extensions, implementation techniques for adapting to multiprocessors, and performance factors in the resulting system. Adding parallelism to Smalltalk code is easy, because programs already use control abstractions like iterators. Smalltalk's basic control and concurrency primitives (lambda expressions, processes and semaphores) can be used to build parallel control abstractions, including parallel iterators, parallel objects, atomic objects, and futures. Language extensions for concurrency are not required. This implementation demonstrates that it is possible to build an efficient parallel object-oriented programming system and illustrates techniques for doing so. Three modification tools-serialization, replication, and reorganization-adapted the Berkeley Smalltalk interpreter to the Firefly multiprocessor. Multiprocessor Smalltalk's performance shows that the combination of multiprocessing and object-oriented programming can be effective: speedups (relative to the original serial version) exceed 2.0 for five processors on all the benchmarks; the median efficiency is 48%. Analysis shows both where performance is lost and how to improve and generalize the experimental results. Changes in the interpreter to support concurrency add at most 12% overhead; better access to per-process variables could eliminate much of that. Changes in the user code to express concurrency add as much as 70% overhead; this overhead could be reduced to 54% if blocks (lambda expressions) were reentrant. Performance is also lost when the program cannot keep all five processors busy.

  9. The co-development of looking dynamics and discrimination performance.

    PubMed

    Perone, Sammy; Spencer, John P

    2014-03-01

    The study of looking dynamics and discrimination form the backbone of developmental science and are central processes in theories of infant cognition. Looking dynamics and discrimination change dramatically across the 1st year of life. Surprisingly, developmental changes in looking and discrimination have not been studied together. Recent simulations of a dynamic neural field (DNF) model of infant looking and memory suggest that looking and discrimination do change together over development and arise from a single neurodevelopmental mechanism. We probed this claim by measuring looking dynamics and discrimination along continuous, metrically organized dimensions in 5-, 7-, and 10-month-old infants (N = 119). The results showed that looking dynamics and discrimination changed together over development and are linked within individuals. Quantitative simulations of a DNF model provide insights into the processes that underlie developmental change in looking dynamics and discrimination. Simulation results support the view that these changes might arise from a single neurodevelopmental mechanism.

  10. The impact of dynamic balance measures on walking performance in multiple sclerosis

    PubMed Central

    Fritz, Nora E.; Marasigan, Rhul Evans R.; Calabresi, Peter A.; Newsome, Scott D.; Zackowski, Kathleen M.

    2014-01-01

    Background Static posture imbalance and gait dysfunction are common in individuals with multiple sclerosis (MS). Although the impact of strength and static balance on walking has been examined, little is known about the impact of dynamic standing balance on walking in MS. Objective To determine the impact of dynamic balance, static balance, sensation, and strength measures to walking in individuals with MS. Methods 52 individuals with MS (27 females; 26 relapsing-remitting; mean age 45.6±10.3 years; median EDSS 3.5 (range 0-7) participated in testing for dynamic and static posturography (Kistler 9281 force plate), hip flexion, hip extension, and ankle dorsiflexion strength (Microfet2 hand-held dynamometer), sensation (Vibratron II) and walk velocity (Optotrak Motion Analysis System). Mann-Whitney tests, Spearman correlation coefficients, and forward stepwise multiple regression were used to assess statistical significance. Results All measures were significantly abnormal in MS subjects when compared to age and sex-matched norms (p<0.05 for all). Static balance (eyes open, feet together [EOFT]), anterior- posterior (AP) dynamic sway, and hip extension strength were strongly correlated with fast walking velocity (AP sway r=0.68; hip extension strength r=0.73; EOFT r=-0.40). Together, AP dynamic sway (ρr=0.71, p<0.001), hip extension strength (ρr=0.54, p<0.001), and EOFT static balance (ρr=-0.41, p=0.01) explained more than 70% of the variance in fast walking velocity (p<0.001). Conclusions These data suggest that AP dynamic sway impacts walking performance in MS. A combined evaluation of dynamic balance, static balance and strength may lead to a better understanding of walking mechanisms as well as the development of strategies to improve walking. PMID:24795162

  11. Static and dynamic posterior cingulate cortex nodal topology of default mode network predicts attention task performance.

    PubMed

    Lin, Pan; Yang, Yong; Jovicich, Jorge; De Pisapia, Nicola; Wang, Xiang; Zuo, Chun S; Levitt, James Jonathan

    2016-03-01

    Characterization of the default mode network (DMN) as a complex network of functionally interacting dynamic systems has received great interest for the study of DMN neural mechanisms. In particular, understanding the relationship of intrinsic resting-state DMN brain network with cognitive behaviors is an important issue in healthy cognition and mental disorders. However, it is still unclear how DMN functional connectivity links to cognitive behaviors during resting-state. In this study, we hypothesize that static and dynamic DMN nodal topology is associated with upcoming cognitive task performance. We used graph theory analysis in order to understand better the relationship between the DMN functional connectivity and cognitive behavior during resting-state and task performance. Nodal degree of the DMN was calculated as a metric of network topology. We found that the static and dynamic posterior cingulate cortex (PCC) nodal degree within the DMN was associated with task performance (Reaction Time). Our results show that the core node PCC nodal degree within the DMN was significantly correlated with reaction time, which suggests that the PCC plays a key role in supporting cognitive function.

  12. Multipole Algorithms for Molecular Dynamics Simulation on High Performance Computers.

    NASA Astrophysics Data System (ADS)

    Elliott, William Dewey

    1995-01-01

    A fundamental problem in modeling large molecular systems with molecular dynamics (MD) simulations is the underlying N-body problem of computing the interactions between all pairs of N atoms. The simplest algorithm to compute pair-wise atomic interactions scales in runtime {cal O}(N^2), making it impractical for interesting biomolecular systems, which can contain millions of atoms. Recently, several algorithms have become available that solve the N-body problem by computing the effects of all pair-wise interactions while scaling in runtime less than {cal O}(N^2). One algorithm, which scales {cal O}(N) for a uniform distribution of particles, is called the Greengard-Rokhlin Fast Multipole Algorithm (FMA). This work describes an FMA-like algorithm called the Molecular Dynamics Multipole Algorithm (MDMA). The algorithm contains several features that are new to N-body algorithms. MDMA uses new, efficient series expansion equations to compute general 1/r^{n } potentials to arbitrary accuracy. In particular, the 1/r Coulomb potential and the 1/r^6 portion of the Lennard-Jones potential are implemented. The new equations are based on multivariate Taylor series expansions. In addition, MDMA uses a cell-to-cell interaction region of cells that is closely tied to worst case error bounds. The worst case error bounds for MDMA are derived in this work also. These bounds apply to other multipole algorithms as well. Several implementation enhancements are described which apply to MDMA as well as other N-body algorithms such as FMA and tree codes. The mathematics of the cell -to-cell interactions are converted to the Fourier domain for reduced operation count and faster computation. A relative indexing scheme was devised to locate cells in the interaction region which allows efficient pre-computation of redundant information and prestorage of much of the cell-to-cell interaction. Also, MDMA was integrated into the MD program SIgMA to demonstrate the performance of the program over

  13. Impact of wind generator infed on dynamic performance of a power system

    NASA Astrophysics Data System (ADS)

    Alam, Md. Ahsanul

    Wind energy is one of the most prominent sources of electrical energy in the years to come. A tendency to increase the amount of electricity generation from wind turbine can be observed in many countries. One of the major concerns related to the high penetration level of the wind energy into the existing power grid is its influence on power system dynamic performance. In this thesis, the impact of wind generation system on power system dynamic performance is investigated through detailed dynamic modeling of the entire wind generator system considering all the relevant components. Nonlinear and linear models of a single machine as well as multimachine wind-AC system have been derived. For the dynamic model of integrated wind-AC system, a general transformation matrix is determined for the transformation of machine and network quantities to a common reference frame. Both time-domain and frequency domain analyses on single machine and multimachine systems have been carried out. The considered multimachine systems are---A 4 machine 12 bus system, and 10 machine 39 bus New England system. Through eigenvalue analysis, impact of asynchronous wind system on overall network damping has been quantified and modes responsible for the instability have been identified. Over with a number of simulation studies it is observed that for a induction generator based wind generation system, the fixed capacitor located at the generator terminal cannot normally cater for the reactive power demand during the transient disturbances like wind gust and fault on the system. For weak network connection, system instability may be initiated because of induction generator terminal voltage collapse under certain disturbance conditions. Incorporation of dynamic reactive power compensation scheme through either variable susceptance control or static compensator (STATCOM) is found to improve the dynamic performance significantly. Further improvement in transient profile has been brought in by

  14. Nominal Performance Biosphere Dose Conversion Factor Analysis

    SciTech Connect

    M. Wasiolek

    2004-09-08

    This analysis report is one of the technical reports containing documentation of the Environmental Radiation Model for Yucca Mountain, Nevada (ERMYN), a biosphere model supporting the Total System Performance Assessment (TSPA) for the license application (LA) for the Yucca Mountain repository. This analysis report describes the development of biosphere dose conversion factors (BDCFs) for the groundwater exposure scenario, and the development of conversion factors for assessing compliance with the groundwater protection standard. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows the interrelationships among the products (i.e., analysis and model reports) developed for biosphere modeling and provides an understanding of how this analysis report contributes to biosphere modeling. This report is one of two reports that develop biosphere BDCFs, which are input parameters for the TSPA-LA model. The ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) describes in detail the ERMYN conceptual model and mathematical model. The input parameter reports, shown to the right of the ''Biosphere Model Report'' in Figure 1-1, contain detailed description of the model input parameters, their development, and the relationship between the parameters and specific features events and processes (FEPs). This report describes biosphere model calculations and their output, the BDCFs, for the groundwater exposure scenario. The objectives of this analysis are to develop BDCFs for the groundwater exposure scenario for the three climate states considered in the TSPA-LA as well as conversion factors for evaluating compliance with the groundwater protection standard. The BDCFs will be used in performance assessment for calculating all-pathway annual doses for a given concentration of radionuclides in groundwater. The conversion factors will be used for calculating gross alpha particle activity in groundwater and the annual dose

  15. Automated Cache Performance Analysis And Optimization

    SciTech Connect

    Mohror, Kathryn

    2013-12-23

    While there is no lack of performance counter tools for coarse-grained measurement of cache activity, there is a critical lack of tools for relating data layout to cache behavior to application performance. Generally, any nontrivial optimizations are either not done at all, or are done ”by hand” requiring significant time and expertise. To the best of our knowledge no tool available to users measures the latency of memory reference instructions for partic- ular addresses and makes this information available to users in an easy-to-use and intuitive way. In this project, we worked to enable the Open|SpeedShop performance analysis tool to gather memory reference latency information for specific instructions and memory ad- dresses, and to gather and display this information in an easy-to-use and intuitive way to aid performance analysts in identifying problematic data structures in their codes. This tool was primarily designed for use in the supercomputer domain as well as grid, cluster, cloud-based parallel e-commerce, and engineering systems and middleware. Ultimately, we envision a tool to automate optimization of application cache layout and utilization in the Open|SpeedShop performance analysis tool. To commercialize this soft- ware, we worked to develop core capabilities for gathering enhanced memory usage per- formance data from applications and create and apply novel methods for automatic data structure layout optimizations, tailoring the overall approach to support existing supercom- puter and cluster programming models and constraints. In this Phase I project, we focused on infrastructure necessary to gather performance data and present it in an intuitive way to users. With the advent of enhanced Precise Event-Based Sampling (PEBS) counters on recent Intel processor architectures and equivalent technology on AMD processors, we are now in a position to access memory reference information for particular addresses. Prior to the introduction of PEBS counters

  16. Dynamic neural networks based on-line identification and control of high performance motor drives

    NASA Technical Reports Server (NTRS)

    Rubaai, Ahmed; Kotaru, Raj

    1995-01-01

    In the automated and high-tech industries of the future, there wil be a need for high performance motor drives both in the low-power range and in the high-power range. To meet very straight demands of tracking and regulation in the two quadrants of operation, advanced control technologies are of a considerable interest and need to be developed. In response a dynamics learning control architecture is developed with simultaneous on-line identification and control. the feature of the proposed approach, to efficiently combine the dual task of system identification (learning) and adaptive control of nonlinear motor drives into a single operation is presented. This approach, therefore, not only adapts to uncertainties of the dynamic parameters of the motor drives but also learns about their inherent nonlinearities. In fact, most of the neural networks based adaptive control approaches in use have an identification phase entirely separate from the control phase. Because these approaches separate the identification and control modes, it is not possible to cope with dynamic changes in a controlled process. Extensive simulation studies have been conducted and good performance was observed. The robustness characteristics of neuro-controllers to perform efficiently in a noisy environment is also demonstrated. With this initial success, the principal investigator believes that the proposed approach with the suggested neural structure can be used successfully for the control of high performance motor drives. Two identification and control topologies based on the model reference adaptive control technique are used in this present analysis. No prior knowledge of load dynamics is assumed in either topology while the second topology also assumes no knowledge of the motor parameters.

  17. Performance analysis for second-design space Stirling engine model

    NASA Astrophysics Data System (ADS)

    Ogiwara, Sachio; Fujiwara, Tsutomu; Eguchi, Kunihisa; Nakamura, Yoshihiro

    A hybrid free-piston Stirling research engine, called NALSEM 125, has been tested since 1988 as part of a solar dynamic power technology program. It is a gamma-type Stirling driven linear-alternator machine with helium as a working fluid. The objective of the experimental program is to understand the thermodynamic and dynamic mechanisms of the free piston engine integrated with a magnet-moving alternator. After the first phase engine experiments of NALSEM 125, a second design Stirling engine of NALSEM 125 R has been tested. By using a second-order analytical tool, some design modifications were performed to provide much more stable dynamic operations over a required operating range, as well as to incorporate an electric heater head simulating a hot interface of 12 sodium heat pipes. Describes in this paper are thermodynamic performance data of NALSEM 125R operations, which are also compared with the computational analysis, considering the power losses resulting from pressure drop and gas leakage.

  18. Engine dynamic analysis with general nonlinear finite element codes

    NASA Technical Reports Server (NTRS)

    Adams, M. L.; Padovan, J.; Fertis, D. G.

    1991-01-01

    A general engine dynamic analysis as a standard design study computational tool is described for the prediction and understanding of complex engine dynamic behavior. Improved definition of engine dynamic response provides valuable information and insights leading to reduced maintenance and overhaul costs on existing engine configurations. Application of advanced engine dynamic simulation methods provides a considerable cost reduction in the development of new engine designs by eliminating some of the trial and error process done with engine hardware development.

  19. Statistical Performance Analysis of Data-Driven Neural Models.

    PubMed

    Freestone, Dean R; Layton, Kelvin J; Kuhlmann, Levin; Cook, Mark J

    2017-02-01

    Data-driven model-based analysis of electrophysiological data is an emerging technique for understanding the mechanisms of seizures. Model-based analysis enables tracking of hidden brain states that are represented by the dynamics of neural mass models. Neural mass models describe the mean firing rates and mean membrane potentials of populations of neurons. Various neural mass models exist with different levels of complexity and realism. An ideal data-driven model-based analysis framework will incorporate the most realistic model possible, enabling accurate imaging of the physiological variables. However, models must be sufficiently parsimonious to enable tracking of important variables using data. This paper provides tools to inform the realism versus parsimony trade-off, the Bayesian Cramer-Rao (lower) Bound (BCRB). We demonstrate how the BCRB can be used to assess the feasibility of using various popular neural mass models to track epilepsy-related dynamics via stochastic filtering methods. A series of simulations show how optimal state estimates relate to measurement noise, model error and initial state uncertainty. We also demonstrate that state estimation accuracy will vary between seizure-like and normal rhythms. The performance of the extended Kalman filter (EKF) is assessed against the BCRB. This work lays a foundation for assessing feasibility of model-based analysis. We discuss how the framework can be used to design experiments to better understand epilepsy.

  20. The Association between Unilateral Heel-Rise Performance with Static and Dynamic Balance in Community Dwelling Older Adults

    PubMed Central

    Hashish, Rami; Samarawickrame, Sachithra D.; Wang, Man-Ying; Yu, Sean S-Y; Salem, George J.

    2014-01-01

    INTRODUCTION As a measure of both strength and muscle endurance of the plantar flexors, the unilateral heel rise (UHR) test has been suggested as a method to evaluate balance capabilities in older adults. Thus, the purpose of this study was to examine the association between UHR performance with biomechanical measures of balance in seniors. MATERIALS AND METHODS Twenty-two older adults completed two testing sessions. The first visit included UHR performance; the second visit included dynamic and static motion analysis. RESULTS UHR performance was significantly associated with dynamic balance capability as measured by medial-lateral inclination angle during gait. As indicated by an analysis of center of pressure, there were significant associations between UHR performance and measures of static balance. DISCUSSION AND CONCLUSION Balance is influenced by plantar flexor performance as measured by the UHR test. We therefore suggest incorporating the UHR test in analyses of balance in seniors. PMID:25457285

  1. Finite element dynamic analysis on CDC STAR-100 computer

    NASA Technical Reports Server (NTRS)

    Noor, A. K.; Lambiotte, J. J., Jr.

    1978-01-01

    Computational algorithms are presented for the finite element dynamic analysis of structures on the CDC STAR-100 computer. The spatial behavior is described using higher-order finite elements. The temporal behavior is approximated by using either the central difference explicit scheme or Newmark's implicit scheme. In each case the analysis is broken up into a number of basic macro-operations. Discussion is focused on the organization of the computation and the mode of storage of different arrays to take advantage of the STAR pipeline capability. The potential of the proposed algorithms is discussed and CPU times are given for performing the different macro-operations for a shell modeled by higher order composite shallow shell elements having 80 degrees of freedom.

  2. Analysis of flexible aircraft longitudinal dynamics and handling qualities. Volume 2: Data

    NASA Technical Reports Server (NTRS)

    Waszak, M. R.; Schmidt, D. K.

    1985-01-01

    Two analysis methods are applied to a family of flexible aircraft in order to investigate how and when structural (especially dynamic aeroelastic) effects affect the dynamic characteristics of aircraft. The first type of analysis is an open loop modal analysis technique. This method considers the effect of modal residue magnitudes on determining vehicle handling qualities. The second method is a pilot in the loop analysis procedure that considers several closed loop system characteristics. Both analyses indicated that dynamic aeroelastic effects caused a degradation in vehicle tracking performance, based on the evaluation of some simulation results. Volume 2 consists of the presentation of the state variable models of the flexible aircraft configurations used in the analysis applications mode shape plots for the structural modes, numerical results from the modal analysis frequency response plots from the pilot in the loop analysis and a listing of the modal analysis computer program.

  3. The Co-Development of Looking Dynamics and Discrimination Performance

    ERIC Educational Resources Information Center

    Perone, Sammy; Spencer, John P.

    2014-01-01

    The study of looking dynamics and discrimination form the backbone of developmental science and are central processes in theories of infant cognition. Looking dynamics and discrimination change dramatically across the 1st year of life. Surprisingly, developmental changes in looking and discrimination have not been studied together. Recent…

  4. Performance management in healthcare: a critical analysis.

    PubMed

    Hewko, Sarah J; Cummings, Greta G

    2016-01-01

    Purpose - The purpose of this paper is to explore the underlying theoretical assumptions and implications of current micro-level performance management and evaluation (PME) practices, specifically within health-care organizations. PME encompasses all activities that are designed and conducted to align employee outputs with organizational goals. Design/methodology/approach - PME, in the context of healthcare, is analyzed through the lens of critical theory. Specifically, Habermas' theory of communicative action is used to highlight some of the questions that arise in looking critically at PME. To provide a richer definition of key theoretical concepts, the authors conducted a preliminary, exploratory hermeneutic semantic analysis of the key words "performance" and "management" and of the term "performance management". Findings - Analysis reveals that existing micro-level PME systems in health-care organizations have the potential to create a workforce that is compliant, dependent, technically oriented and passive, and to support health-care systems in which inequalities and power imbalances are perpetually reinforced. Practical implications - At a time when the health-care system is under increasing pressure to provide high-quality, affordable services with fewer resources, it may be wise to investigate new sector-specific ways of evaluating and managing performance. Originality/value - In this paper, written for health-care leaders and health human resource specialists, the theoretical assumptions and implications of current PME practices within health-care organizations are explored. It is hoped that readers will be inspired to support innovative PME practices within their organizations that encourage peak performance among health-care professionals.

  5. Pallidal spiking activity reflects learning dynamics and predicts performance

    PubMed Central

    Noblejas, Maria Imelda; Mizrahi, Aviv D.; Dauber, Omer; Bergman, Hagai

    2016-01-01

    The basal ganglia (BG) network has been divided into interacting actor and critic components, modulating the probabilities of different state–action combinations through learning. Most models of learning and decision making in the BG focus on the roles of the striatum and its dopaminergic inputs, commonly overlooking the complexities and interactions of BG downstream nuclei. In this study, we aimed to reveal the learning-related activity of the external segment of the globus pallidus (GPe), a downstream structure whose computational role has remained relatively unexplored. Recording from monkeys engaged in a deterministic three-choice reversal learning task, we found that changes in GPe discharge rates predicted subsequent behavioral shifts on a trial-by-trial basis. Furthermore, the activity following the shift encoded whether it resulted in reward or not. The frequent changes in stimulus–outcome contingencies (i.e., reversals) allowed us to examine the learning-related neural activity and show that GPe discharge rates closely matched across-trial learning dynamics. Additionally, firing rates exhibited a linear decrease in sequences of correct responses, possibly reflecting a gradual shift from goal-directed execution to automaticity. Thus, modulations in GPe spiking activity are highest for attention-demanding aspects of behavior (i.e., switching choices) and decrease as attentional demands decline (i.e., as performance becomes automatic). These findings are contrasted with results from striatal tonically active neurons, which show none of these task-related modulations. Our results demonstrate that GPe, commonly studied in motor contexts, takes part in cognitive functions, in which movement plays a marginal role. PMID:27671661

  6. Steady-state and dynamic performance of a gas-lubricated seal

    NASA Technical Reports Server (NTRS)

    Colsher, R.; Shapiro, W.

    1972-01-01

    Steady-state and dynamic performance of a gas-lubricated, self-acting face seal was determined using numerical methods based on a variable grid, finite-difference, time-transient procedure. Results were obtained for a gas turbine main shaft seal operating at 206.9 newton per square centimeter (300 psi) sealed air pressure and 152.4 meters per second (500 ft/sec) sliding velocity. Analysis of the seal dynamics revealed that the response of the seal nosepiece to runout of the seat face is markedly affected by secondary seal friction and by nosepiece inertia. The nosepiece response was determined for various levels of secondary seal friction and seat face runout magnitudes.

  7. Supersonic Flight Dynamics Test 1 - Post-Flight Assessment of Simulation Performance

    NASA Technical Reports Server (NTRS)

    Dutta, Soumyo; Bowes, Angela L.; Striepe, Scott A.; Davis, Jody L.; Queen, Eric M.; Blood, Eric M.; Ivanov, Mark C.

    2015-01-01

    NASA's Low Density Supersonic Decelerator (LDSD) project conducted its first Supersonic Flight Dynamics Test (SFDT-1) on June 28, 2014. Program to Optimize Simulated Trajectories II (POST2) was one of the flight dynamics codes used to simulate and predict the flight performance and Monte Carlo analysis was used to characterize the potential flight conditions experienced by the test vehicle. This paper compares the simulation predictions with the reconstructed trajectory of SFDT-1. Additionally, off-nominal conditions seen during flight are modeled in post-flight simulations to find the primary contributors that reconcile the simulation with flight data. The results of these analyses are beneficial for the pre-flight simulation and targeting of the follow-on SFDT flights currently scheduled for summer 2015.

  8. Application of the Tool for Turbine Engine Closed-Loop Transient Analysis (TTECTrA) for Dynamic Systems Analysis

    NASA Technical Reports Server (NTRS)

    Csank, Jeffrey T.; Zinnecker, Alicia M.

    2014-01-01

    The aircraft engine design process seeks to achieve the best overall system-level performance, weight, and cost for a given engine design. This is achieved by a complex process known as systems analysis, where steady-state simulations are used to identify trade-offs that should be balanced to optimize the system. The steady-state simulations and data on which systems analysis relies may not adequately capture the true performance trade-offs that exist during transient operation. Dynamic Systems Analysis provides the capability for assessing these trade-offs at an earlier stage of the engine design process. The concept of dynamic systems analysis and the type of information available from this analysis are presented in this paper. To provide this capability, the Tool for Turbine Engine Closed-loop Transient Analysis (TTECTrA) was developed. This tool aids a user in the design of a power management controller to regulate thrust, and a transient limiter to protect the engine model from surge at a single flight condition (defined by an altitude and Mach number). Results from simulation of the closed-loop system may be used to estimate the dynamic performance of the model. This enables evaluation of the trade-off between performance and operability, or safety, in the engine, which could not be done with steady-state data alone. A design study is presented to compare the dynamic performance of two different engine models integrated with the TTECTrA software.

  9. IBIS detector performance during calibration - preliminary analysis

    NASA Astrophysics Data System (ADS)

    Bazzano, A.; Bird, A. J.; Laurent, P.; Malaguti, G.; Quadrini, E. M.; Segreto, A.; Volkmer, R.; del Santo, M.; Gabriele, M.; Tikkanen, T.

    2003-11-01

    The IBIS telescope is a high angular resolution gamma-ray imager due to be launched on the INTEGRAL satellite on October 17, 2002. The scientific goal of IBIS is to study astrophysical processes from celestial sources and diffuse regions in the hard X-ray and soft gamma-ray domains. IBIS features a coded aperture imaging system and a novel large area (~3000cm2) multilayer pixellated detector which utilises both cadmium telluride (16,384 detectors) and caesium iodide elements (4096 detectors) surrounded by a BGO active veto shield. We present an overview of, and preliminary analysis from, the IBIS calibration campaign. The performance of each pixel has been characterised, and hence the scientific performance of the IBIS detector system as a whole can now be established.

  10. Analysis approaches and interventions with occupational performance

    PubMed Central

    Ahn, Sinae

    2016-01-01

    [Purpose] The purpose of this study was to analyze approaches and interventions with occupational performance in patients with stroke. [Subjects and Methods] In this study, articles published in the past 10 years were searched. The key terms used were “occupational performance AND stroke” and “occupational performance AND CVA”. A total 252 articles were identified, and 79 articles were selected. All interventions were classified according to their approaches according to 6 theories. All interventions were analyzed for frequency. [Results] Regarding the approaches, there were 25 articles for studies that provided high frequency interventions aimed at improving biomechanical approaches (31.6%). This included electrical stimulation therapy, robot therapy, and sensory stimulation training, as well as others. Analysis of the frequency of interventions revealed that the most commonly used interventions, which were used in 18 articles (22.8%), made use of the concept of constraint-induced therapy. [Conclusion] The results of this study suggest an approach for use in clinics for selecting an appropriate intervention for occupational performance. PMID:27799719

  11. Performance analysis of quantum dots infrared photodetector

    NASA Astrophysics Data System (ADS)

    Liu, Hongmei; Zhang, Fangfang; Zhang, Jianqi; He, Guojing

    2011-08-01

    Performance analysis of the quantum dots infrared photodetector(QDIP), which can provide device designers with theoretical guidance and experimental verification, arouses a wide interest and becomes a hot research topic in the recent years. In the paper, in comparison with quantum well infrared photodetector(QWIP) characteristic, the performance of QDIP is mainly discussed and summarized by analyzing the special properties of quantum dots material. To be specific, the dark current density and the detectivity in the normalized incident phenomenon are obtained from Phillip performance model, the carrier lifetime and the dark current of QDIP are studied by combing with the "photon bottleneck" effect, and the detectivity of QDIP is theoretically derived from considering photoconduction gain under the influence of the capture probability. From the experimental results, a conclusion is made that QDIP can not only receive the normal incidence light, but also has the advantages of the long carrier life, the big photoconductive gain, the low dark current and so on, and it further illustrates a anticipated superiority of QDIP in performance and a wide use of QDIP in many engineering fields in the future.

  12. Diversity Performance Analysis on Multiple HAP Networks

    PubMed Central

    Dong, Feihong; Li, Min; Gong, Xiangwu; Li, Hongjun; Gao, Fengyue

    2015-01-01

    One of the main design challenges in wireless sensor networks (WSNs) is achieving a high-data-rate transmission for individual sensor devices. The high altitude platform (HAP) is an important communication relay platform for WSNs and next-generation wireless networks. Multiple-input multiple-output (MIMO) techniques provide the diversity and multiplexing gain, which can improve the network performance effectively. In this paper, a virtual MIMO (V-MIMO) model is proposed by networking multiple HAPs with the concept of multiple assets in view (MAV). In a shadowed Rician fading channel, the diversity performance is investigated. The probability density function (PDF) and cumulative distribution function (CDF) of the received signal-to-noise ratio (SNR) are derived. In addition, the average symbol error rate (ASER) with BPSK and QPSK is given for the V-MIMO model. The system capacity is studied for both perfect channel state information (CSI) and unknown CSI individually. The ergodic capacity with various SNR and Rician factors for different network configurations is also analyzed. The simulation results validate the effectiveness of the performance analysis. It is shown that the performance of the HAPs network in WSNs can be significantly improved by utilizing the MAV to achieve overlapping coverage, with the help of the V-MIMO techniques. PMID:26134102

  13. Nominal Performance Biosphere Dose Conversion Factor Analysis

    SciTech Connect

    M.A. Wasiolek

    2005-04-28

    This analysis report is one of the technical reports containing documentation of the Environmental Radiation Model for Yucca Mountain, Nevada (ERMYN), a biosphere model supporting the Total System Performance Assessment (TSPA) for the license application (LA) for the Yucca Mountain repository. This analysis report describes the development of biosphere dose conversion factors (BDCFs) for the groundwater exposure scenario, and the development of conversion factors for assessing compliance with the groundwater protection standards. A graphical representation of the documentation hierarchy for the ERMYN is presented in Figure 1-1. This figure shows the interrelationships among the products (i.e., analysis and model reports) developed for biosphere modeling and provides an understanding of how this analysis report contributes to biosphere modeling. This report is one of two reports that develop BDCFs, which are input parameters for the TSPA-LA model. The ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) describes in detail the ERMYN conceptual model and mathematical model. The input parameter reports, shown to the right of the ''Biosphere Model Report'' in Figure 1-1, contain detailed description of the model input parameters, their development, and the relationship between the parameters and specific features events and processes (FEPs). This report describes biosphere model calculations and their output, the BDCFs, for the groundwater exposure scenario. This analysis receives direct input from the outputs of the ''Biosphere Model Report'' (BSC 2004 [DIRS 169460]) and the five analyses that develop parameter values for the biosphere model (BSC 2005 [DIRS 172827]; BSC 2004 [DIRS 169672]; BSC 2004 [DIRS 169673]; BSC 2004 [DIRS 169458]; BSC 2004 [DIRS 169459]). The results of this report are further analyzed in the ''Biosphere Dose Conversion Factor Importance and Sensitivity Analysis'' (Figure 1-1). The objectives of this analysis are to develop BDCFs for the

  14. Idaho National Laboratory Quarterly Performance Analysis

    SciTech Connect

    Mitchell, Lisbeth

    2014-11-01

    This report is published quarterly by the Idaho National Laboratory (INL) Quality and Performance Management Organization. The Department of Energy (DOE) Occurrence Reporting and Processing System (ORPS), as prescribed in DOE Order 232.2, “Occurrence Reporting and Processing of Operations Information,” requires a quarterly analysis of events, both reportable and not reportable, for the previous 12 months. This report is the analysis of 60 reportable events (23 from the 4th Qtr FY14 and 37 from the prior three reporting quarters) as well as 58 other issue reports (including not reportable events and Significant Category A and B conditions) identified at INL from July 2013 through October 2014. Battelle Energy Alliance (BEA) operates the INL under contract DE AC07 051D14517.

  15. Monte Carlo analysis: error of extrapolated thermal conductivity from molecular dynamics simulations

    SciTech Connect

    Liu, Xiang-Yang; Andersson, Anders David

    2016-11-07

    In this short report, we give an analysis of the extrapolated thermal conductivity of UO2 from earlier molecular dynamics (MD) simulations [1]. Because almost all material properties are functions of temperature, e.g. fission gas release, the fuel thermal conductivity is the most important parameter from a model sensitivity perspective [2]. Thus, it is useful to perform such analysis.

  16. Tethered Satellite System (TSS) Dynamics Assessments and Analysis, TSS-1R Post Flight Data Evaluation

    NASA Technical Reports Server (NTRS)

    Glaese, John R.

    1996-01-01

    The purpose of this report is to document the analysis performed on the TSS-1R telemetry data after the flight. These analysis addressed the tether dynamics of TSS-1r. The telemetry data was provided in a CD-ROM format. The data contained on the CD-ROM was selected from available Satellite and orbiter MSID's.

  17. Dynamic analysis of the GEOS satellite

    NASA Technical Reports Server (NTRS)

    Meirovitch, L.; Juang, J. N.; Chang, C. P.

    1975-01-01

    The assumed modes method is used to investigate the stability of the GEOS satellite. The system is discretized by representing the continuous displacement by finite series of space-dependent admissible functions multiplied by time-dependent generalized coordinates. The spatial dependence is eliminated by integration over the elastic domains, so that the testing functional reduces to a testing function. The sign properties of the testing function are then tested and the equilibrium defined as nontrivial. In considering the stability of small motions about nontrivial equilibrium, it is shown that if the analysis performed by ignoring the motion of the mass center indicates stability, then the system remains stable if the motion of the mass center is included.

  18. Dynamic Performance Assessment of Side Facing Troop Seats During Impact

    DTIC Science & Technology

    2016-04-30

    Biodynamics and Protection Group of the Applied Neuroscience Branch (711 HPW/RHCPT) agreed to conduct a dynamic comparative test program of currently...compare how effectively the seats protected occupants ranging from the 5th percentile female to 98th percentile male. A series of ten tests using each...Aircrew Biodynamics and Protection Group of the Applied Neuroscience Branch (711 HPW/RHCPT) agreed to conduct a dynamic comparative test program of

  19. Dynamic SVL and body bias for low leakage power and high performance in CMOS digital circuits

    NASA Astrophysics Data System (ADS)

    Deshmukh, Jyoti; Khare, Kavita

    2012-12-01

    In this article, a new complementary metal oxide semiconductor design scheme called dynamic self-controllable voltage level (DSVL) is proposed. In the proposed scheme, leakage power is controlled by dynamically disconnecting supply to inactive blocks and adjusting body bias to further limit leakage and to maintain performance. Leakage power measurements at 1.8 V, 75°C demonstrate power reduction by 59.4% in case of 1 bit full adder and by 43.0% in case of a chain of four inverters using SVL circuit as a power switch. Furthermore, we achieve leakage power reduction by 94.7% in case of 1 bit full adder and by 91.8% in case of a chain of four inverters using dynamic body bias. The forward body bias of 0.45 V applied in active mode improves the maximum operating frequency by 16% in case of 1 bit full adder and 5.55% in case of a chain of inverters. Analysis shows that additional benefits of using the DSVL and body bias include high performance, low leakage power consumption in sleep mode, single threshold implementation and state retention even in standby mode.

  20. Application of the Tool for Turbine Engine Closed-loop Transient Analysis (TTECTrA) for Dynamic Systems Analysis

    NASA Technical Reports Server (NTRS)

    Csank, Jeffrey Thomas; Zinnecker, Alicia Mae

    2014-01-01

    Systems analysis involves steady-state simulations of combined components to evaluate the steady-state performance, weight, and cost of a system; dynamic considerations are not included until later in the design process. The Dynamic Systems Analysis task, under NASAs Fixed Wing project, is developing the capability for assessing dynamic issues at earlier stages during systems analysis. To provide this capability the Tool for Turbine Engine Closed-loop Transient Analysis (TTECTrA) has been developed to design a single flight condition controller (defined as altitude and Mach number) and, ultimately, provide an estimate of the closed-loop performance of the engine model. This tool has been integrated with the Commercial Modular Aero-Propulsion System Simulation 40,000 (CMAPSS 40k) engine model to demonstrate the additional information TTECTrA makes available for dynamic systems analysis. This dynamic data can be used to evaluate the trade-off between performance and safety, which could not be done with steady-state systems analysis data. TTECTrA has been designed to integrate with any turbine engine model that is compatible with the MATLAB Simulink (The MathWorks, Inc.) environment.

  1. Application of the Tool for Turbine Engine Closed-loop Transient Analysis (TTECTrA) for Dynamic Systems Analysis

    NASA Technical Reports Server (NTRS)

    Csank, Jeffrey; Zinnecker, Alicia

    2014-01-01

    Systems analysis involves steady-state simulations of combined components to evaluate the steady-state performance, weight, and cost of a system; dynamic considerations are not included until later in the design process. The Dynamic Systems Analysis task, under NASAs Fixed Wing project, is developing the capability for assessing dynamic issues at earlier stages during systems analysis. To provide this capability the Tool for Turbine Engine Closed-loop Transient Analysis (TTECTrA) has been developed to design a single flight condition controller (defined as altitude and Mach number) and, ultimately, provide an estimate of the closed-loop performance of the engine model. This tool has been integrated with the Commercial Modular Aero-Propulsion System Simulation 40,000(CMAPSS40k) engine model to demonstrate the additional information TTECTrA makes available for dynamic systems analysis. This dynamic data can be used to evaluate the trade-off between performance and safety, which could not be done with steady-state systems analysis data. TTECTrA has been designed to integrate with any turbine engine model that is compatible with the MATLABSimulink (The MathWorks, Inc.) environment.

  2. Failure analysis of high performance ballistic fibers

    NASA Astrophysics Data System (ADS)

    Spatola, Jennifer S.

    High performance fibers have a high tensile strength and modulus, good wear resistance, and a low density, making them ideal for applications in ballistic impact resistance, such as body armor. However, the observed ballistic performance of these fibers is much lower than the predicted values. Since the predictions assume only tensile stress failure, it is safe to assume that the stress state is affecting fiber performance. The purpose of this research was to determine if there are failure mode changes in the fiber fracture when transversely loaded by indenters of different shapes. An experimental design mimicking transverse impact was used to determine any such effects. Three different indenters were used: round, FSP, and razor blade. The indenter height was changed to change the angle of failure tested. Five high performance fibers were examined: KevlarRTM KM2, SpectraRTM 130d, DyneemaRTM SK-62 and SK-76, and ZylonRTM 555. Failed fibers were analyzed using an SEM to determine failure mechanisms. The results show that the round and razor blade indenters produced a constant failure strain, as well as failure mechanisms independent of testing angle. The FSP indenter produced a decrease in failure strain as the angle increased. Fibrillation was the dominant failure mechanism at all angles for the round indenter, while through thickness shearing was the failure mechanism for the razor blade. The FSP indenter showed a transition from fibrillation at low angles to through thickness shearing at high angles, indicating that the round and razor blade indenters are extreme cases of the FSP indenter. The failure mechanisms observed with the FSP indenter at various angles correlated with the experimental strain data obtained during fiber testing. This indicates that geometry of the indenter tip in compression is a contributing factor in lowering the failure strain of the high performance fibers. TEM analysis of the fiber failure mechanisms was also attempted, though without

  3. Nominal Performance Biosphere Dose Conversion Factor Analysis

    SciTech Connect

    Wasiolek, Maryla A.

    2000-12-21

    The purpose of this report was to document the process leading to development of the Biosphere Dose Conversion Factors (BDCFs) for the postclosure nominal performance of the potential repository at Yucca Mountain. BDCF calculations concerned twenty-four radionuclides. This selection included sixteen radionuclides that may be significant nominal performance dose contributors during the compliance period of up to 10,000 years, five additional radionuclides of importance for up to 1 million years postclosure, and three relatively short-lived radionuclides important for the human intrusion scenario. Consideration of radionuclide buildup in soil caused by previous irrigation with contaminated groundwater was taken into account in the BDCF development. The effect of climate evolution, from the current arid conditions to a wetter and cooler climate, on the BDCF values was evaluated. The analysis included consideration of different exposure pathway's contribution to the BDCFs. Calculations of nominal performance BDCFs used the GENII-S computer code in a series of probabilistic realizations to propagate the uncertainties of input parameters into the output. BDCFs for the nominal performance, when combined with the concentrations of radionuclides in groundwater allow calculation of potential radiation doses to the receptor of interest. Calculated estimates of radionuclide concentration in groundwater result from the saturated zone modeling. The integration of the biosphere modeling results (BDCFs) with the outcomes of the other component models is accomplished in the Total System Performance Assessment (TSPA) to calculate doses to the receptor of interest from radionuclides postulated to be released to the environment from the potential repository at Yucca Mountain.

  4. Bayesian Analysis of Individual Level Personality Dynamics

    PubMed Central

    Cripps, Edward; Wood, Robert E.; Beckmann, Nadin; Lau, John; Beckmann, Jens F.; Cripps, Sally Ann

    2016-01-01

    A Bayesian technique with analyses of within-person processes at the level of the individual is presented. The approach is used to examine whether the patterns of within-person responses on a 12-trial simulation task are consistent with the predictions of ITA theory (Dweck, 1999). ITA theory states that the performance of an individual with an entity theory of ability is more likely to spiral down following a failure experience than the performance of an individual with an incremental theory of ability. This is because entity theorists interpret failure experiences as evidence of a lack of ability which they believe is largely innate and therefore relatively fixed; whilst incremental theorists believe in the malleability of abilities and interpret failure experiences as evidence of more controllable factors such as poor strategy or lack of effort. The results of our analyses support ITA theory at both the within- and between-person levels of analyses and demonstrate the benefits of Bayesian techniques for the analysis of within-person processes. These include more formal specification of the theory and the ability to draw inferences about each individual, which allows for more nuanced interpretations of individuals within a personality category, such as differences in the individual probabilities of spiraling. While Bayesian techniques have many potential advantages for the analyses of processes at the level of the individual, ease of use is not one of them for psychologists trained in traditional frequentist statistical techniques. PMID:27486415

  5. Dynamical systems analysis applied to working memory data.

    PubMed

    Gasimova, Fidan; Robitzsch, Alexander; Wilhelm, Oliver; Boker, Steven M; Hu, Yueqin; Hülür, Gizem

    2014-01-01

    In the present paper we investigate weekly fluctuations in the working memory capacity (WMC) assessed over a period of 2 years. We use dynamical system analysis, specifically a second order linear differential equation, to model weekly variability in WMC in a sample of 112 9th graders. In our longitudinal data we use a B-spline imputation method to deal with missing data. The results show a significant negative frequency parameter in the data, indicating a cyclical pattern in weekly memory updating performance across time. We use a multilevel modeling approach to capture individual differences in model parameters and find that a higher initial performance level and a slower improvement at the MU task is associated with a slower frequency of oscillation. Additionally, we conduct a simulation study examining the analysis procedure's performance using different numbers of B-spline knots and values of time delay embedding dimensions. Results show that the number of knots in the B-spline imputation influence accuracy more than the number of embedding dimensions.

  6. Dynamic analysis of multimesh-gear helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Choy, Fred K.; Townsend, Dennis P.; Oswald, Fred B.

    1988-01-01

    A dynamic analysis of multimesh-gear helicopter transmission systems was performed by correlating analytical simulations with experimental investigations. The two computer programs used in this study, GRDYNMLT and PGT, were developed under NASA/Army sponsorship. Parametric studies of the numerical model with variations on mesh damping ratios, operating speeds, tip-relief tooth modifications, and tooth-spacing errors were performed to investigate the accuracy, application, and limitations of the two computer programs. Although similar levels of dynamic loading were predicted by both programs, the computer code GRDYNMLT was found to be superior and broader in scope. Results from analytical work were also compared with experimental data obtained from the U.S. Army's UH-60A Black Hawk 2240-kW (3000-hp) class, twin-engine helicopter transmission tested at the NASA Lewis Research Center. Good correlation in gear stresses was obtained between the analytical model simulated by GRDYNMLT and the experimental measurements. More realistic mesh damping can be predicted through experimental data correlation.

  7. Dynamic Analysis of Fuel Cycle Transitioning

    SciTech Connect

    Brent Dixon; Steve Piet; David Shropshire; Gretchen Matthern

    2009-09-01

    This paper examines the time-dependent dynamics of transitioning from a once-through fuel cycle to a closed fuel cycle. The once-through system involves only Light Water Reactors (LWRs) operating on uranium oxide fuel UOX), while the closed cycle includes both LWRs and fast spectrum reactors (FRs) in either a single-tier system or two-tier fuel system. The single-tier system includes full transuranic recycle in FRs while the two-tier system adds one pass of mixed oxide uranium-plutonium (MOX U-Pu) fuel in the LWR. While the analysis primarily focuses on burner fast reactors, transuranic conversion ratios up to 1.0 are assessed and many of the findings apply to any fuel cycle transitioning from a thermal once-through system to a synergistic thermal-fast recycle system. These findings include uranium requirements for a range of nuclear electricity growth rates, the importance of back end fuel cycle facility timing and magnitude, the impact of employing a range of fast reactor conversion ratios, system sensitivity to used fuel cooling time prior to recycle, impacts on a range of waste management indicators, and projected electricity cost ranges for once-through, single-tier and two-tier systems. The study confirmed that significant waste management benefits can be realized as soon as recycling is initiated, but natural uranium savings are minimal in this century. The use of MOX in LWRs decouples the development of recycle facilities from fast reactor fielding, but also significantly delays and limits fast reactor deployment. In all cases, fast reactor deployment was significantly below than predicted by static equilibrium analyses.

  8. Static and Dynamics of a Pump Impeller with a Balancing Device Part II: Dynamic Analysis

    NASA Astrophysics Data System (ADS)

    Martsinkovsky, V. A.; Zhulyov, A.; Kundera, C.

    2014-08-01

    This paper presents the theoretical study of the system comprising an impeller and a balancing device. It deals with the dynamic analysis of the system, i.e., the axial vibrations of the impeller, and the system stability. The dynamic analysis took into account linearized hydrodynamic forces and moments generated in the longitudinal clearances of the seals of the impeller. The theoretical analysis was supplemented with a numerical example with characteristics determined for a real single-stage centrifugal pump

  9. Arrhythmic dynamics from singularity analysis of electrocardiographic maps.

    PubMed

    Pont, Oriol; Yahia, Hussein; Xu, Binbin

    2013-01-01

    From a point view of nonlinear dynamics, the electrical activity of the heart is a complex dynamical system, whose dynamics reflects the actual state of health of the heart. Nonlinear signal-processing methods are needed in order to accurately characterize these signals and improve understanding of cardiac arrhythmias. Recent developments on reconstructible signals and multiscale information content show that an analysis in terms of singularity exponents provides compact and meaningful descriptors of the structure and dynamics of the system. Such approach gives a compact representation atrial arrhythmic dynamics, which can sharply highlight regime transitions and arrhythmogenic areas.

  10. Numerical Analysis of Constrained Dynamical Systems, with Applications to Dynamic Contact of Solids, Nonlinear Elastodynamics and Fluid-Structure Interactions

    DTIC Science & Technology

    2000-12-01

    NUMERICAL ANALYSIS OF CONSTRAINED DYNAMICAL SYSTEMS, WITH APPLICATIONS TO DYNAMIC CONTACT OF SOLIDS, NONLINEAR ELASTODYNAMICS AND FLUID-STRUCTURE...2000 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Numerical Analysis of Constrained Dynamical Systems, with 5b. GRANT NUMBER Applications to Dynamic...This extension allows the analysis of fluid-structure interfaces through the Lagrangian contact logic previously developed. Similarly, we have developed

  11. Effect of electron spin dynamics on solid-state dynamic nuclear polarization performance.

    PubMed

    Siaw, Ting Ann; Fehr, Matthias; Lund, Alicia; Latimer, Allegra; Walker, Shamon A; Edwards, Devin T; Han, Song-I

    2014-09-21

    For the broadest dissemination of solid-state dynamic nuclear polarization (ssDNP) enhanced NMR as a material characterization tool, the ability to employ generic mono-nitroxide radicals as spin probes is critical. A better understanding of the factors contributing to ssDNP efficiency is needed to rationally optimize the experimental condition for the practically accessible spin probes at hand. This study seeks to advance the mechanistic understanding of ssDNP by examining the effect of electron spin dynamics on ssDNP performance at liquid helium temperatures (4-40 K). The key observation is that bi-radicals and mono-radicals can generate comparable nuclear spin polarization at 4 K and 7 T, which is in contrast to the observation for ssDNP at liquid nitrogen temperatures (80-150 K) that finds bi-radicals to clearly outperform mono-radicals. To rationalize this observation, we analyze the change in the DNP-induced nuclear spin polarization (Pn) and the characteristic ssDNP signal buildup time as a function of electron spin relaxation rates that are modulated by the mono- and bi-radical spin concentration. Changes in Pn are consistent with a systematic variation in the product of the electron spin-lattice relaxation time and the electron spin flip-flop rate that constitutes an integral saturation factor of an inhomogeneously broadened EPR spectrum. We show that the comparable Pn achieved with both radical species can be reconciled with a comparable integral EPR saturation factor. Surprisingly, the largest Pn is observed at an intermediate spin concentration for both mono- and bi-radicals. At the highest radical concentration, the stronger inter-electron spin dipolar coupling favors ssDNP, while oversaturation diminishes Pn, as experimentally verified by the observation of a maximum Pn at an intermediate, not the maximum, microwave (μw) power. At the maximum μw power, oversaturation reduces the electron spin population differential that must be upheld between

  12. Visibility graph analysis on heartbeat dynamics of meditation training

    NASA Astrophysics Data System (ADS)

    Jiang, Sen; Bian, Chunhua; Ning, Xinbao; Ma, Qianli D. Y.

    2013-06-01

    We apply the visibility graph analysis to human heartbeat dynamics by constructing the complex networks of heartbeat interval time series and investigating the statistical properties of the network before and during chi and yoga meditation. The experiment results show that visibility graph analysis can reveal the dynamical changes caused by meditation training manifested as regular heartbeat, which is closely related to the adjustment of autonomous neural system, and visibility graph analysis is effective to evaluate the effect of meditation.

  13. Dynamic Analysis of Mcfc Porous Electrode

    NASA Astrophysics Data System (ADS)

    Lee, Gwo-Lin Kevin

    1992-01-01

    The intent of this work is to develop AC impedance measurements, in combination with other methods, as a tool to determine the relative importance of various resistance sources in the multi-step process occurring at a gas-diffusion porous electrode. In particular, the case of a MCFC cathode is studied. The goals of this study are: (1) elucidation of electrode mechanism; (2) analysis of the porous electrode performance for the purpose of optimizing design; and (3) developing the capabilities of AC impedance as an index of long-term cell performance decay. The oxygen reduction reaction of molten carbonate fuel cell and the corresponding kinetic as well as transport parameters were tried to be estimated by using impedance techniques combining with other electrochemical methods from flag, wire and rotating disk electrodes in pot cell as well as porous electrode in lab cell. The dominant pathway for oxygen reduction in 62%Li _2CO_3/38%K _2CO_3 melt at 650^circC is via superoxide ions. This follows from flag electrode impedance results indicating that O_sp{2}{ -}/CO_2 mixed diffusion is the dominant source of resistance. The polarization behavior of gas-diffusion porous electrodes has been analyzed in terms of individual voltage loss and overall voltage loss. In most cases, the optimal electrolyte filling will be obtained when the dominant source of voltage loss switches from ohmic or mass transfer resistances to kinetic activation resistance, and similar behavior for optimal electrode thickness. Pressurized operation is favorable for performance if the reaction mechanism follows the superoxide mechanism, but not if the peroxide path dominates. A distributed-network approach has been developed and it is concluded that a digital simulation of AC-superimposed -on-DC impedance of a porous electrode is possible and helpful. Kinetic activation and mass transfer resistances are extracted separate and conclude that both peroxide and superoxide contribute the oxygen reduction

  14. Dynamic fractal signature dissimilarity analysis for therapeutic response assessment using dynamic contrast-enhanced MRI

    PubMed Central

    Wang, Chunhao; Subashi, Ergys; Yin, Fang-Fang; Chang, Zheng

    2016-01-01

    Purpose: To develop a dynamic fractal signature dissimilarity (FSD) method as a novel image texture analysis technique for the quantification of tumor heterogeneity information for better therapeutic response assessment with dynamic contrast-enhanced (DCE)-MRI. Methods: A small animal antiangiogenesis drug treatment experiment was used to demonstrate the proposed method. Sixteen LS-174T implanted mice were randomly assigned into treatment and control groups (n = 8/group). All mice received bevacizumab (treatment) or saline (control) three times in two weeks, and one pretreatment and two post-treatment DCE-MRI scans were performed. In the proposed dynamic FSD method, a dynamic FSD curve was generated to characterize the heterogeneity evolution during the contrast agent uptake, and the area under FSD curve (AUCFSD) and the maximum enhancement (MEFSD) were selected as representative parameters. As for comparison, the pharmacokinetic parameter Ktrans map and area under MR intensity enhancement curve AUCMR map were calculated. Besides the tumor’s mean value and coefficient of variation, the kurtosis, skewness, and classic Rényi dimensions d1 and d2 of Ktrans and AUCMR maps were evaluated for heterogeneity assessment for comparison. For post-treatment scans, the Mann–Whitney U-test was used to assess the differences of the investigated parameters between treatment/control groups. The support vector machine (SVM) was applied to classify treatment/control groups using the investigated parameters at each post-treatment scan day. Results: The tumor mean Ktrans and its heterogeneity measurements d1 and d2 values showed significant differences between treatment/control groups in the second post-treatment scan. In contrast, the relative values (in reference to the pretreatment value) of AUCFSD and MEFSD in both post-treatment scans showed significant differences between treatment/control groups. When using AUCFSD and MEFSD as SVM input for treatment/control classification

  15. Conceptual Design Optimization of an Augmented Stability Aircraft Incorporating Dynamic Response Performance Constraints

    NASA Technical Reports Server (NTRS)

    Welstead, Jason

    2014-01-01

    This research focused on incorporating stability and control into a multidisciplinary de- sign optimization on a Boeing 737-class advanced concept called the D8.2b. A new method of evaluating the aircraft handling performance using quantitative evaluation of the sys- tem to disturbances, including perturbations, continuous turbulence, and discrete gusts, is presented. A multidisciplinary design optimization was performed using the D8.2b transport air- craft concept. The con guration was optimized for minimum fuel burn using a design range of 3,000 nautical miles. Optimization cases were run using xed tail volume coecients, static trim constraints, and static trim and dynamic response constraints. A Cessna 182T model was used to test the various dynamic analysis components, ensuring the analysis was behaving as expected. Results of the optimizations show that including stability and con- trol in the design process drastically alters the optimal design, indicating that stability and control should be included in conceptual design to avoid system level penalties later in the design process.

  16. Performance analysis of jump-gliding locomotion for miniature robotics.

    PubMed

    Vidyasagar, A; Zufferey, Jean-Christohphe; Floreano, Dario; Kovač, M

    2015-03-26

    Recent work suggests that jumping locomotion in combination with a gliding phase can be used as an effective mobility principle in robotics. Compared to pure jumping without a gliding phase, the potential benefits of hybrid jump-gliding locomotion includes the ability to extend the distance travelled and reduce the potentially damaging impact forces upon landing. This publication evaluates the performance of jump-gliding locomotion and provides models for the analysis of the relevant dynamics of flight. It also defines a jump-gliding envelope that encompasses the range that can be achieved with jump-gliding robots and that can be used to evaluate the performance and improvement potential of jump-gliding robots. We present first a planar dynamic model and then a simplified closed form model, which allow for quantification of the distance travelled and the impact energy on landing. In order to validate the prediction of these models, we validate the model with experiments using a novel jump-gliding robot, named the 'EPFL jump-glider'. It has a mass of 16.5 g and is able to perform jumps from elevated positions, perform steered gliding flight, land safely and traverse on the ground by repetitive jumping. The experiments indicate that the developed jump-gliding model fits very well with the measured flight data using the EPFL jump-glider, confirming the benefits of jump-gliding locomotion to mobile robotics. The jump-glide envelope considerations indicate that the EPFL jump-glider, when traversing from a 2 m height, reaches 74.3% of optimal jump-gliding distance compared to pure jumping without a gliding phase which only reaches 33.4% of the optimal jump-gliding distance. Methods of further improving flight performance based on the models and inspiration from biological systems are presented providing mechanical design pathways to future jump-gliding robot designs.

  17. Performance Analysis of Intelligent Robust Facility Layout Design

    NASA Astrophysics Data System (ADS)

    Moslemipour, G.; Lee, T. S.; Loong, Y. T.

    2017-03-01

    Design of a robust production facility layout with minimum handling cost (MHC) presents an appropriate approach to tackle facility layout problems in a dynamic volatile environment, in which product demands randomly change in each planning period. The objective of the design is to find the robust facility layout with minimum total material handling cost over the entire multi-period planning horizon. This paper proposes a new mathematical model for designing robust machine layout in the stochastic dynamic environment of manufacturing systems using quadratic assignment problem (QAP) formulation. In this investigation, product demands are assumed to be normally distributed random variables with known expected value, variance, and covariance that randomly change from period to period. The proposed model was verified and validated using randomly generated numerical data and benchmark examples. The effect of dependent product demands and varying interest rate on the total cost function of the proposed model has also been investigated. Sensitivity analysis on the proposed model has been performed. Dynamic programming and simulated annealing optimization algorithms were used in solving the modeled example problems.

  18. Dynamic analysis for robot arm control

    NASA Technical Reports Server (NTRS)

    Bejczy, A. K.

    1983-01-01

    Explicit state equations provide detailed analytic insight into the dynamic behavior of a robot arm and facilitate the understanding of the control problem. The analytic strength of explicit state equations is exemplified for a given robot arm. In fact, for the quoted example, the explicit and exact state equations involve considerably less computation than the use of the known most efficient general-purpose computational algorithm for robot arm dynamics.

  19. Development of methodology for horizontal axis wind turbine dynamic analysis

    NASA Technical Reports Server (NTRS)

    Dugundji, J.

    1982-01-01

    Horizontal axis wind turbine dynamics were studied. The following findings are summarized: (1) review of the MOSTAS computer programs for dynamic analysis of horizontal axis wind turbines; (2) review of various analysis methods for rotating systems with periodic coefficients; (3) review of structural dynamics analysis tools for large wind turbine; (4) experiments for yaw characteristics of a rotating rotor; (5) development of a finite element model for rotors; (6) development of simple models for aeroelastics; and (7) development of simple models for stability and response of wind turbines on flexible towers.

  20. Teachers' Performances during a Practical Dynamic Open Inquiry Process

    ERIC Educational Resources Information Center

    Zion, Michal; Schanin, Ilana; Shmueli, Ester Rimerman

    2013-01-01

    The research goal of this study was to determine whether teachers who participated in an inquiry-based course were able to internalize a dynamic open inquiry process. This study focused on 25 science teachers who participated in an annual inquiry-based academic course. Several teaching tools helped teachers employ an open inquiry process. We…

  1. Hubble Space Telescope Pointing Performance Due to Micro-Dynamic Disturbances from the NICMOS Cryogenic Cooler

    NASA Technical Reports Server (NTRS)

    Clapp, Brian R.; Sills, Joel W., Jr.; Voorhees, Carl R.; Griffin, Thomas J. (Technical Monitor)

    2002-01-01

    The Vibration Admittance Test (VET) was performed to measure the emitted disturbances of the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) Cryogenic Cooler (NCC) in preparation for NCC installation onboard the Hubble Space Telescope (HST) during Servicing Mission 3B (SM3B). Details of the VET ground-test are described, including facility characteristics, sensor complement and configuration, NCC suspension, and background noise measurements. Kinematic equations used to compute NCC mass center displacements and accelerations from raw measurements are presented, and dynamic equations of motion for the NCC VET system are developed and verified using modal test data. A MIMO linear frequency-domain analysis method is used to compute NCC-induced loads and HST boresight jitter from VET measurements. These results are verified by a nonlinear time-domain analysis approach using a high-fidelity structural dynamics and pointing control simulation for HST. NCC emitted acceleration levels not exceeding 35 micro-g rms were measured in the VET and analysis methods herein predict 3.1 milli-areseconds rms jitter for HST on-orbit. Because the NCC is predicted to become the predominant disturbance source for HST, VET results indicate that HST will continue to meet the 7 milli-arcsecond pointing stability mission requirement in the post-SM3B era.

  2. Axial and centrifugal pump meanline performance analysis

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.

    1994-01-01

    A meanline pump flow modeling method has been developed to provide a fast capability for modeling pumps of cryogenic rocket engines. Based on this method, a meanline pump flow code (PUMPA) has been written that can predict the performance of pumps at off-design operating conditions, given the loss of the diffusion system at the design point. The design point rotor efficiency is obtained from empirically derived correlations of loss to rotor specific speed. The rapid input setup and computer run time for the meanline pump flow code makes it an effective analysis and conceptual design tool. The map generation capabilities of the PUMPA code provide the information needed for interfacing with a rocket engine system modeling code.

  3. Dynamic contact angle analysis of silicone hydrogel contact lenses.

    PubMed

    Read, Michael Leonard; Morgan, Philip Bruce; Kelly, Jeremiah Michael; Maldonado-Codina, Carole

    2011-07-01

    Contact angle measurements are used to infer the clinical wetting characteristics of contact lenses. Such characterization has become more commonplace since the introduction of silicone hydrogel contact lens materials, which have been associated with reduced in vivo wetting due to the inclusion of siloxane-containing components. Using consistent methodology and a single investigator, advancing and receding contact angles were measured for 11 commercially available silicone hydrogel contact lens types with a dynamic captive bubble technique employing customized, fully automated image analysis. Advancing contact angles were found to range between 20° and 72° with the lenses falling into six statistically discrete groupings. Receding contact angles fell within a narrower range, between 17° and 22°, with the lenses segregated into three groups. The relationship between these laboratory measurements and the clinical performance of the lenses requires further investigation.

  4. Analysis of planetary evolution with emphasis on differentiation and dynamics

    NASA Technical Reports Server (NTRS)

    Kaula, William M.; Newman, William I.

    1987-01-01

    In order to address the early stages of nebula evolution, a three-dimensional collapse code which includes not only hydrodynamics and radiative transfer, but also the effects of ionization and, possibly, magnetic fields is being addressed. As part of the examination of solar system evolution, an N-body code was developed which describes the latter stages of planet formation from the accretion of planetesimals. To test the code for accuracy and run-time efficiency, and to develop a stronger theoretical foundation, problems were studied in orbital dynamics. A regional analysis of the correlation in the gravity and topography fields of Venus was performed in order to determine the small and intermediate scale subsurface structure.

  5. State machine analysis of sensor data from dynamic processes

    DOEpatents

    Cook, William R.; Brabson, John M.; Deland, Sharon M.

    2003-12-23

    A state machine model analyzes sensor data from dynamic processes at a facility to identify the actual processes that were performed at the facility during a period of interest for the purpose of remote facility inspection. An inspector can further input the expected operations into the state machine model and compare the expected, or declared, processes to the actual processes to identify undeclared processes at the facility. The state machine analysis enables the generation of knowledge about the state of the facility at all levels, from location of physical objects to complex operational concepts. Therefore, the state machine method and apparatus may benefit any agency or business with sensored facilities that stores or manipulates expensive, dangerous, or controlled materials or information.

  6. Coupled climate network analysis of multidecadal dynamics in the Arctic

    NASA Astrophysics Data System (ADS)

    Wiedermann, M.; Donges, J. F.; Heitzig, J.; Kurths, J.

    2012-04-01

    Climate network analysis provides a powerful tool for investigating the correlation structure of the dynamical system Earth. Elements of time series analysis and the theory of complex networks are combined to give new insights into the dynamics of the climate system by delivering a spatially resolved image of the underlying correlation structure from which the network is constructed. Recent results have indicated a possible correlation between the Atlantic Multidecadal Oscillation (AMO) and the Pacific Decadal Oscillation (PDO) with a time lag of 15 to 30 years. However, identifying the involved physical mechanisms remains an open problem of ocean science and atmospheric research. We perform a climate network analysis aiming at assessing the importance of the Arctic for this connection between North Atlantic and North Pacific. As storm tracks were suggested to play a role and the large delay between AMO and PDO points to oceanic processes at work, we focus on analyzing the coupling structure between oceanic sea surface temperature (SST) and atmospheric sea level pressure (SAP) as well as geopotential height (GPH) fields. We employ the recently developed theory of interacting networks, with the corresponding statistical cross-network measures, that enables us to study the properties of a coupled climate network that divides into several subnetworks representing horizontal fields of different observables. As the analysis is performed in a region close to the north pole one has to bear in mind that climatological datasets are often arranged on a rectangular grid such that the density of nodes increases rapidly towards the poles. To correct for the distortions in our results resulting from this inhomogenous node density, we refine the cross-network measures in a way that enables us to assign every node with an individual weight according to the area that the node represents on the Earth's surface. This method has already been applied to the standard set of measures

  7. Stormwater quality models: performance and sensitivity analysis.

    PubMed

    Dotto, C B S; Kleidorfer, M; Deletic, A; Fletcher, T D; McCarthy, D T; Rauch, W

    2010-01-01

    The complex nature of pollutant accumulation and washoff, along with high temporal and spatial variations, pose challenges for the development and establishment of accurate and reliable models of the pollution generation process in urban environments. Therefore, the search for reliable stormwater quality models remains an important area of research. Model calibration and sensitivity analysis of such models are essential in order to evaluate model performance; it is very unlikely that non-calibrated models will lead to reasonable results. This paper reports on the testing of three models which aim to represent pollutant generation from urban catchments. Assessment of the models was undertaken using a simplified Monte Carlo Markov Chain (MCMC) method. Results are presented in terms of performance, sensitivity to the parameters and correlation between these parameters. In general, it was suggested that the tested models poorly represent reality and result in a high level of uncertainty. The conclusions provide useful information for the improvement of existing models and insights for the development of new model formulations.

  8. Past Performance analysis of HPOTP bearings

    NASA Technical Reports Server (NTRS)

    Bhat, B. N.; Dolan, F. J.

    1982-01-01

    The past performance analysis conducted on three High Pressure Oxygen Turbopump (HPOTP) bearings from the Space Shuttle Main Engine is presented. Metallurgical analysis of failed bearing balls and races, and wear track and crack configuration analyses were carried out. In addition, one bearing was tested in laboratory at very high axial loads. The results showed that the cracks were surface initiated and propagated into subsurface locations at relatively small angles. Subsurface cracks were much more extensive than was appeared on the surface. The location of major cracks in the races corresponded to high radial loads rather than high axial loads. There was evidence to suggest that the inner races were heated to elevated temperatures. A failure scenario was developed based on the above findings. According to this scenario the HPOTP bearings are heated by a combination of high loads and high coefficient of friction (poor lubrication). Different methods of extending the HPOTP bearing life are also discussed. These include reduction of axial loads, improvements in bearing design, lubrication and cooling, and use of improved bearing materials.

  9. Radio-science performance analysis software

    NASA Technical Reports Server (NTRS)

    Morabito, D. D.; Asmar, S. W.

    1995-01-01

    The Radio Science Systems Group (RSSG) provides various support functions for several flight project radio-science teams. Among these support functions are uplink and sequence planning, real-time operations monitoring and support, data validation, archiving and distribution functions, and data processing and analysis. This article describes the support functions that encompass radio-science data performance analysis. The primary tool used by the RSSG to fulfill this support function is the STBLTY program set. STBLTY is used to reconstruct observable frequencies and calculate model frequencies, frequency residuals, frequency stability in terms of Allan deviation, reconstructed phase, frequency and phase power spectral density, and frequency drift rates. In the case of one-way data, using an ultrastable oscillator (USO) as a frequency reference, the program set computes the spacecraft transmitted frequency and maintains a database containing the in-flight history of the USO measurements. The program set also produces graphical displays. Some examples and discussions on operating the program set on Galileo and Ulysses data will be presented.

  10. Performance Analysis of ICA in Sensor Array

    PubMed Central

    Cai, Xin; Wang, Xiang; Huang, Zhitao; Wang, Fenghua

    2016-01-01

    As the best-known scheme in the field of Blind Source Separation (BSS), Independent Component Analysis (ICA) has been intensively used in various domains, including biomedical and acoustics applications, cooperative or non-cooperative communication, etc. While sensor arrays are involved in most of the applications, the influence on the performance of ICA of practical factors therein has not been sufficiently investigated yet. In this manuscript, the issue is researched by taking the typical antenna array as an illustrative example. Factors taken into consideration include the environment noise level, the properties of the array and that of the radiators. We analyze the analytic relationship between the noise variance, the source variance, the condition number of the mixing matrix and the optimal signal to interference-plus-noise ratio, as well as the relationship between the singularity of the mixing matrix and practical factors concerned. The situations where the mixing process turns (nearly) singular have been paid special attention to, since such circumstances are critical in applications. Results and conclusions obtained should be instructive when applying ICA algorithms on mixtures from sensor arrays. Moreover, an effective countermeasure against the cases of singular mixtures has been proposed, on the basis of previous analysis. Experiments validating the theoretical conclusions as well as the effectiveness of the proposed scheme have been included. PMID:27164100

  11. Radio-science performance analysis software

    NASA Astrophysics Data System (ADS)

    Morabito, D. D.; Asmar, S. W.

    1995-02-01

    The Radio Science Systems Group (RSSG) provides various support functions for several flight project radio-science teams. Among these support functions are uplink and sequence planning, real-time operations monitoring and support, data validation, archiving and distribution functions, and data processing and analysis. This article describes the support functions that encompass radio-science data performance analysis. The primary tool used by the RSSG to fulfill this support function is the STBLTY program set. STBLTY is used to reconstruct observable frequencies and calculate model frequencies, frequency residuals, frequency stability in terms of Allan deviation, reconstructed phase, frequency and phase power spectral density, and frequency drift rates. In the case of one-way data, using an ultrastable oscillator (USO) as a frequency reference, the program set computes the spacecraft transmitted frequency and maintains a database containing the in-flight history of the USO measurements. The program set also produces graphical displays. Some examples and discussions on operating the program set on Galileo and Ulysses data will be presented.

  12. Potential Flow Analysis of Dynamic Ground Effect

    NASA Technical Reports Server (NTRS)

    Feifel, W. M.

    1999-01-01

    Interpretation of some flight test data suggests the presence of a 'dynamic ground effect'. The lift of an aircraft approaching the ground depends on the rate of descent and is lower than the aircraft steady state lift at a same height above the ground. Such a lift deficiency under dynamic conditions could have a serious impact on the overall aircraft layout. For example, the increased pitch angle needed to compensate for the temporary loss in lift would reduce the tail strike margin or require an increase in landing gear length. Under HSR2 an effort is under way to clarify the dynamic ground effect issue using a multi-pronged approach. A dynamic ground effect test has been run in the NASA Langley 14x22 ft wind tunnel. Northup-Grumman is conducting time accurate CFD (Computational Fluid Dynamics) Euler analyses on the National Aerodynamic Simulator facility. Boeing has been using linear potential flow methodology which are thought to provide much needed insight in, physics of this very complex problem. The present report summarizes the results of these potential flow studies.

  13. Aeroservoelastic and Flight Dynamics Analysis Using Computational Fluid Dynamics

    NASA Technical Reports Server (NTRS)

    Arena, Andrew S., Jr.

    1999-01-01

    This document in large part is based on the Masters Thesis of Cole Stephens. The document encompasses a variety of technical and practical issues involved when using the STARS codes for Aeroservoelastic analysis of vehicles. The document covers in great detail a number of technical issues and step-by-step details involved in the simulation of a system where aerodynamics, structures and controls are tightly coupled. Comparisons are made to a benchmark experimental program conducted at NASA Langley. One of the significant advantages of the methodology detailed is that as a result of the technique used to accelerate the CFD-based simulation, a systems model is produced which is very useful for developing the control law strategy, and subsequent high-speed simulations.

  14. Dynamic Performance of a Residential Air-to-Air Heat Pump.

    ERIC Educational Resources Information Center

    Kelly, George E.; Bean, John

    This publication is a study of the dynamic performance of a 5-ton air-to-air heat pump in a residence in Washington, D.C. The effect of part-load operation on the heat pump's cooling and heating coefficients of performance was determined. Discrepancies between measured performance and manufacturer-supplied performance data were found when the unit…

  15. Overview af MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2004-01-01

    This paper presents viewgraphs on NASA Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group Activities. The topics include: 1) Status of programs at MSFC; 2) Fluid Mechanics at MSFC; 3) Relevant Fluid Dynamics Activities at MSFC; and 4) Shuttle Return to Flight.

  16. Nonlinear dynamic analysis for elastic robotic arms

    NASA Astrophysics Data System (ADS)

    Korayem, M. H.; Rahimi, H. N.

    2011-06-01

    The aim of the paper is to analyze the nonlinear dynamics of robotic arms with elastic links and joints. The main contribution of the paper is the comparative assessment of assumed modes and finite element methods as more convenient approaches for computing the nonlinear dynamic of robotic systems. Numerical simulations comprising both methods are carried out and results are discussed. Hence, advantages and disadvantages of each method are illustrated. Then, adding the joint flexibility to the system is dealt with and the obtained model is demonstrated. Finally, a brief description of the optimal motion generation is presented and the simulation is carried out to investigate the role of robot dynamic modeling in the control of robots.

  17. Dynamic Characteristics of Human Motor Performance in Control Systems.

    DTIC Science & Technology

    1979-01-01

    including the neural control of respiration and vestibular organization. In addition, computer simulations of small neuronal networks have added an understanding of circuits involved in motor performance. (Author)

  18. Dynamic analysis of noncontacting face seals

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1980-01-01

    The dynamic behavior of a noncontacting coned face seal is analyzed taking into account various design parameters and operating conditions. The primary seal ring motion is expressed by a set of nonlinear equations for three degrees of freedom. These equations, which are solved numerically, allow identification of two dimensionless groups of parameters that affect the seal dynamic behavior. Stability maps for various seals are presented. These maps contain a stable-to-unstable transition region in which the ring wobbles at half the shaft frequency. The effect of various parameters on seal stability is discussed and an empirical expression for critical stability is offered.

  19. Dynamical scaling analysis of plant callus growth

    NASA Astrophysics Data System (ADS)

    Galeano, J.; Buceta, J.; Juarez, K.; Pumariño, B.; de la Torre, J.; Iriondo, J. M.

    2003-07-01

    We present experimental results for the dynamical scaling properties of the development of plant calli. We have assayed two different species of plant calli, Brassica oleracea and Brassica rapa, under different growth conditions, and show that their dynamical scalings share a universality class. From a theoretical point of view, we introduce a scaling hypothesis for systems whose size evolves in time. We expect our work to be relevant for the understanding and characterization of other systems that undergo growth due to cell division and differentiation, such as, for example, tumor development.

  20. Dynamic State Estimation Utilizing High Performance Computing Methods

    SciTech Connect

    Schneider, Kevin P.; Huang, Zhenyu; Yang, Bo; Hauer, Matthew L.; Nieplocha, Jaroslaw

    2009-03-18

    The state estimation tools which are currently deployed in power system control rooms are based on a quasi-steady-state assumption. As a result, the suite of operational tools that rely on state estimation results as inputs do not have dynamic information available and their accuracy is compromised. This paper presents an overview of the Kalman Filtering process and then focuses on the implementation of the predication component on multiple processors.

  1. Dynamic Performance of Maximum Power Point Trackers in TEG Systems Under Rapidly Changing Temperature Conditions

    NASA Astrophysics Data System (ADS)

    Man, E. A.; Sera, D.; Mathe, L.; Schaltz, E.; Rosendahl, L.

    2016-03-01

    Characterization of thermoelectric generators (TEG) is widely discussed and equipment has been built that can perform such analysis. One method is often used to perform such characterization: constant temperature with variable thermal power input. Maximum power point tracking (MPPT) methods for TEG systems are mostly tested under steady-state conditions for different constant input temperatures. However, for most TEG applications, the input temperature gradient changes, exposing the MPPT to variable tracking conditions. An example is the exhaust pipe on hybrid vehicles, for which, because of the intermittent operation of the internal combustion engine, the TEG and its MPPT controller are exposed to a cyclic temperature profile. Furthermore, there are no guidelines on how fast the MPPT must be under such dynamic conditions. In the work discussed in this paper, temperature gradients for TEG integrated in several applications were evaluated; the results showed temperature variation up to 5°C/s for TEG systems. Electrical characterization of a calcium-manganese oxide TEG was performed at steady-state for different input temperatures and a maximum temperature of 401°C. By using electrical data from characterization of the oxide module, a solar array simulator was emulated to perform as a TEG. A trapezoidal temperature profile with different gradients was used on the TEG simulator to evaluate the dynamic MPPT efficiency. It is known that the perturb and observe (P&O) algorithm may have difficulty accurately tracking under rapidly changing conditions. To solve this problem, a compromise must be found between the magnitude of the increment and the sampling frequency of the control algorithm. The standard P&O performance was evaluated experimentally by using different temperature gradients for different MPPT sampling frequencies, and efficiency values are provided for all cases. The results showed that a tracking speed of 2.5 Hz can be successfully implemented on a TEG

  2. Evaluation of covariance and information performance measures for dynamic object tracking

    NASA Astrophysics Data System (ADS)

    Yang, Chun; Blasch, Erik; Douville, Phil; Kaplan, Lance; Qiu, Di

    2010-04-01

    In surveillance and reconnaissance applications, dynamic objects are dynamically followed by track filters with sequential measurements. There are two popular implementations of tracking filters: one is the covariance or Kalman filter and the other is the information filter. Evaluation of tracking filters is important in performance optimization not only for tracking filter design but also for resource management. Typically, the information matrix is the inverse of the covariance matrix. The covariance filter-based approaches attempt to minimize the covariance matrix-based scalar indexes whereas the information filter-based methods aim at maximizing the information matrix-based scalar indexes. Such scalar performance measures include the trace, determinant, norms (1-norm, 2-norm, infinite-norm, and Forbenius norm), and eigenstructure of the covariance matrix or the information matrix and their variants. One natural question to ask is if the scalar track filter performance measures applied to the covariance matrix are equivalent to those applied to the information matrix? In this paper we show most of the scalar performance indexes are equivalent yet some are not. As a result, the indexes if used improperly would provide an "optimized" solution but in the wrong sense relative to track accuracy. The simulation indicated that all the seven indexes were successful when applied to the covariance matrix. However, the failed indexes for the information filter include the trace and the four norms (as defined in MATLAB) of the information matrix. Nevertheless, the determinant and the properly selected eigenvalue of the information matrix were successful to select the optimal sensor update configuration. The evaluation analysis of track measures can serve as a guideline to determine the suitability of performance measures for tracking filter design and resource management.

  3. Space Shuttle Main Engine performance analysis

    NASA Astrophysics Data System (ADS)

    Santi, L. Michael

    1993-11-01

    For a number of years, NASA has relied primarily upon periodically updated versions of Rocketdyne's power balance model (PBM) to provide space shuttle main engine (SSME) steady-state performance prediction. A recent computational study indicated that PBM predictions do not satisfy fundamental energy conservation principles. More recently, SSME test results provided by the Technology Test Bed (TTB) program have indicated significant discrepancies between PBM flow and temperature predictions and TTB observations. Results of these investigations have diminished confidence in the predictions provided by PBM, and motivated the development of new computational tools for supporting SSME performance analysis. A multivariate least squares regression algorithm was developed and implemented during this effort in order to efficiently characterize TTB data. This procedure, called the 'gains model,' was used to approximate the variation of SSME performance parameters such as flow rate, pressure, temperature, speed, and assorted hardware characteristics in terms of six assumed independent influences. These six influences were engine power level, mixture ratio, fuel inlet pressure and temperature, and oxidizer inlet pressure and temperature. A BFGS optimization algorithm provided the base procedure for determining regression coefficients for both linear and full quadratic approximations of parameter variation. Statistical information relative to data deviation from regression derived relations was also computed. A new strategy for integrating test data with theoretical performance prediction was also investigated. The current integration procedure employed by PBM treats test data as pristine and adjusts hardware characteristics in a heuristic manner to achieve engine balance. Within PBM, this integration procedure is called 'data reduction.' By contrast, the new data integration procedure, termed 'reconciliation,' uses mathematical optimization techniques, and requires both

  4. Space Shuttle Main Engine performance analysis

    NASA Technical Reports Server (NTRS)

    Santi, L. Michael

    1993-01-01

    For a number of years, NASA has relied primarily upon periodically updated versions of Rocketdyne's power balance model (PBM) to provide space shuttle main engine (SSME) steady-state performance prediction. A recent computational study indicated that PBM predictions do not satisfy fundamental energy conservation principles. More recently, SSME test results provided by the Technology Test Bed (TTB) program have indicated significant discrepancies between PBM flow and temperature predictions and TTB observations. Results of these investigations have diminished confidence in the predictions provided by PBM, and motivated the development of new computational tools for supporting SSME performance analysis. A multivariate least squares regression algorithm was developed and implemented during this effort in order to efficiently characterize TTB data. This procedure, called the 'gains model,' was used to approximate the variation of SSME performance parameters such as flow rate, pressure, temperature, speed, and assorted hardware characteristics in terms of six assumed independent influences. These six influences were engine power level, mixture ratio, fuel inlet pressure and temperature, and oxidizer inlet pressure and temperature. A BFGS optimization algorithm provided the base procedure for determining regression coefficients for both linear and full quadratic approximations of parameter variation. Statistical information relative to data deviation from regression derived relations was also computed. A new strategy for integrating test data with theoretical performance prediction was also investigated. The current integration procedure employed by PBM treats test data as pristine and adjusts hardware characteristics in a heuristic manner to achieve engine balance. Within PBM, this integration procedure is called 'data reduction.' By contrast, the new data integration procedure, termed 'reconciliation,' uses mathematical optimization techniques, and requires both

  5. Data Link Performance Analysis for LVLASO Experiments

    NASA Technical Reports Server (NTRS)

    Mukkamala, Ravi

    1998-01-01

    Low-visibility Landing and Surface Operations System (LVLASO) is currently being prototyped and tested at NASA Langley Research Center. Since the main objective of the system is to maintain the aircraft landings and take-offs even during low-visibility conditions, timely exchange of positional and other information between the aircraft and the ground control is critical. For safety and reliability reasons, there are several redundant sources on the ground (e.g., ASDE, AMASS) that collect and disseminate information about the environment to the aircrafts. The data link subsystem of LVLASO is responsible for supporting the timely transfer of information between the aircrafts and the ground controllers. In fact, if not properly designed, the data link subsystem could become a bottleneck in the proper functioning of LVLASO. Currently, the other components of the system are being designed assuming that the data link has adequate capacity and is capable of delivering the information in a timely manner. During August 1-28, 1997, several flight experiments were conducted to test the prototypes of subsystems developed under LVLASO project, The back-round and details of the tests are described in the next section. The test results have been collected in two CDs by FAA and Rockwell-Collins. Under the current grant, we have analyzed the data and evaluated the performance of the Mode S datalink. In this report, we summarize the results of our analysis. Much of the results are shown in terms of graphs or histograms. The test date (or experiment number) was often taken as the X-axis and the Y-axis denotes whatever metric of focus in that chart. In interpreting these charts, one need to take into account the vehicular traffic during a particular experiment. In general, the performance of the data link was found to be quite satisfactory in terms of delivering long and short Mode S squitters from the vehicles to the ground receiver, Similarly, its performance in delivering control

  6. Dynamic network data envelopment analysis for university hospitals evaluation

    PubMed Central

    Lobo, Maria Stella de Castro; Rodrigues, Henrique de Castro; André, Edgard Caires Gazzola; de Azeredo, Jônatas Almeida; Lins, Marcos Pereira Estellita

    2016-01-01

    ABSTRACT OBJECTIVE To develop an assessment tool to evaluate the efficiency of federal university general hospitals. METHODS Data envelopment analysis, a linear programming technique, creates a best practice frontier by comparing observed production given the amount of resources used. The model is output-oriented and considers variable returns to scale. Network data envelopment analysis considers link variables belonging to more than one dimension (in the model, medical residents, adjusted admissions, and research projects). Dynamic network data envelopment analysis uses carry-over variables (in the model, financing budget) to analyze frontier shift in subsequent years. Data were gathered from the information system of the Brazilian Ministry of Education (MEC), 2010-2013. RESULTS The mean scores for health care, teaching and research over the period were 58.0%, 86.0%, and 61.0%, respectively. In 2012, the best performance year, for all units to reach the frontier it would be necessary to have a mean increase of 65.0% in outpatient visits; 34.0% in admissions; 12.0% in undergraduate students; 13.0% in multi-professional residents; 48.0% in graduate students; 7.0% in research projects; besides a decrease of 9.0% in medical residents. In the same year, an increase of 0.9% in financing budget would be necessary to improve the care output frontier. In the dynamic evaluation, there was progress in teaching efficiency, oscillation in medical care and no variation in research. CONCLUSIONS The proposed model generates public health planning and programming parameters by estimating efficiency scores and making projections to reach the best practice frontier. PMID:27191158

  7. Theoretical and software considerations for nonlinear dynamic analysis

    NASA Technical Reports Server (NTRS)

    Schmidt, R. J.; Dodds, R. H., Jr.

    1983-01-01

    In the finite element method for structural analysis, it is generally necessary to discretize the structural model into a very large number of elements to accurately evaluate displacements, strains, and stresses. As the complexity of the model increases, the number of degrees of freedom can easily exceed the capacity of present-day software system. Improvements of structural analysis software including more efficient use of existing hardware and improved structural modeling techniques are discussed. One modeling technique that is used successfully in static linear and nonlinear analysis is multilevel substructuring. This research extends the use of multilevel substructure modeling to include dynamic analysis and defines the requirements for a general purpose software system capable of efficient nonlinear dynamic analysis. The multilevel substructuring technique is presented, the analytical formulations and computational procedures for dynamic analysis and nonlinear mechanics are reviewed, and an approach to the design and implementation of a general purpose structural software system is presented.

  8. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2002-01-01

    This viewgraph report presents an overview of activities and accomplishments of NASA's Marshall Space Flight Center's Applied Fluid Dynamics Analysis Group. Expertise in this group focuses on high-fidelity fluids design and analysis with application to space shuttle propulsion and next generation launch technologies. Topics covered include: computational fluid dynamics research and goals, turbomachinery research and activities, nozzle research and activities, combustion devices, engine systems, MDA development and CFD process improvements.

  9. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Wang, Tee-See; Griffin, Lisa; Turner, James E. (Technical Monitor)

    2001-01-01

    This document is a presentation graphic which reviews the activities of the Applied Fluid Dynamics Analysis Group at Marshall Space Flight Center (i.e., Code TD64). The work of this group focused on supporting the space transportation programs. The work of the group is in Computational Fluid Dynamic tool development. This development is driven by hardware design needs. The major applications for the design and analysis tools are: turbines, pumps, propulsion-to-airframe integration, and combustion devices.

  10. Elementary Applications of a Rotorcraft Dynamic Stability Analysis

    NASA Technical Reports Server (NTRS)

    Johnson, W.

    1976-01-01

    A number of applications of a rotorcraft aeroelastic analysis are presented to verify that the analysis encompasses the classical solutions of rotor dynamics, and to examine the influence of certain features of the model. Results are given for the following topics: flapping frequency response to pitch control; forward flight flapping stability; pitch/flap flutter and divergence; ground resonance instability; and the flight dynamics of several representative helicopters.

  11. Interpolating dynamical systems: Applications to experimental data analysis

    SciTech Connect

    Ecke, R.E.

    1991-01-01

    Experimental data from Rayleigh-Benard convection is used to demonstrate new techniques in data analysis. The data, in the form of Poincare sections, are fit to a map of the plane as a function of a system control parameter. This provides a very useful method for interpolating experimental low-dimensional dynamical systems. The fitted map can then be studied using numerical bifurcation methods or other nonlinear dynamics analysis techniques. 16 refs., 3 figs., 1 tab.

  12. A Dynamic Analysis of Piezoelectric Strained Elements.

    DTIC Science & Technology

    1992-12-01

    of Piezoelectricity , Oxford Univ.Press, Oxford (1990). E38] T.C.Ting, "Dynamic response of composites", Appl. Mechs.Rev., vol. 33, no.12, Dp.1629-16...Plenum Press, New York (1969). 276 [36] J.Zelenka, Piezoelectric Resonators and their Applications, Elsevier, Amsterdam (1986). [37] T.Ikeda, Fundamentals

  13. Dynamic global sensitivity analysis in bioreactor networks for bioethanol production.

    PubMed

    Ochoa, M P; Estrada, V; Di Maggio, J; Hoch, P M

    2016-01-01

    Dynamic global sensitivity analysis (GSA) was performed for three different dynamic bioreactor models of increasing complexity: a fermenter for bioethanol production, a bioreactors network, where two types of bioreactors were considered: aerobic for biomass production and anaerobic for bioethanol production and a co-fermenter bioreactor, to identify the parameters that most contribute to uncertainty in model outputs. Sobol's method was used to calculate time profiles for sensitivity indices. Numerical results have shown the time-variant influence of uncertain parameters on model variables. Most influential model parameters have been determined. For the model of the bioethanol fermenter, μmax (maximum growth rate) and Ks (half-saturation constant) are the parameters with largest contribution to model variables uncertainty; in the bioreactors network, the most influential parameter is μmax,1 (maximum growth rate in bioreactor 1); whereas λ (glucose-to-total sugars concentration ratio in the feed) is the most influential parameter over all model variables in the co-fermentation bioreactor.

  14. Integrating atomistic molecular dynamics simulations, experiments, and network analysis to study protein dynamics: strength in unity.

    PubMed

    Papaleo, Elena

    2015-01-01

    In the last years, we have been observing remarkable improvements in the field of protein dynamics. Indeed, we can now study protein dynamics in atomistic details over several timescales with a rich portfolio of experimental and computational techniques. On one side, this provides us with the possibility to validate simulation methods and physical models against a broad range of experimental observables. On the other side, it also allows a complementary and comprehensive view on protein structure and dynamics. What is needed now is a better understanding of the link between the dynamic properties that we observe and the functional properties of these important cellular machines. To make progresses in this direction, we need to improve the physical models used to describe proteins and solvent in molecular dynamics, as well as to strengthen the integration of experiments and simulations to overcome their own limitations. Moreover, now that we have the means to study protein dynamics in great details, we need new tools to understand the information embedded in the protein ensembles and in their dynamic signature. With this aim in mind, we should enrich the current tools for analysis of biomolecular simulations with attention to the effects that can be propagated over long distances and are often associated to important biological functions. In this context, approaches inspired by network analysis can make an important contribution to the analysis of molecular dynamics simulations.

  15. Integrating atomistic molecular dynamics simulations, experiments, and network analysis to study protein dynamics: strength in unity

    PubMed Central

    Papaleo, Elena

    2015-01-01

    In the last years, we have been observing remarkable improvements in the field of protein dynamics. Indeed, we can now study protein dynamics in atomistic details over several timescales with a rich portfolio of experimental and computational techniques. On one side, this provides us with the possibility to validate simulation methods and physical models against a broad range of experimental observables. On the other side, it also allows a complementary and comprehensive view on protein structure and dynamics. What is needed now is a better understanding of the link between the dynamic properties that we observe and the functional properties of these important cellular machines. To make progresses in this direction, we need to improve the physical models used to describe proteins and solvent in molecular dynamics, as well as to strengthen the integration of experiments and simulations to overcome their own limitations. Moreover, now that we have the means to study protein dynamics in great details, we need new tools to understand the information embedded in the protein ensembles and in their dynamic signature. With this aim in mind, we should enrich the current tools for analysis of biomolecular simulations with attention to the effects that can be propagated over long distances and are often associated to important biological functions. In this context, approaches inspired by network analysis can make an important contribution to the analysis of molecular dynamics simulations. PMID:26075210

  16. Dynamic Analysis of Capture Devices for Momentum Exchange with Tethers

    NASA Technical Reports Server (NTRS)

    Canfield, Stephen

    2002-01-01

    One of the significant challenges in developing a momentum exchange / electrodynamic reboost tether system is in the analysis and design of the capture device and its effects on the overall dynamics of the system. The goal of this work is to develop appropriate tether momentum exchange models that can simulate and evaluate the requirements of such a system, and be used to create specifications on the design of a capture device. This report briefly describes dynamic model development, simulation of the momentum exchange process, evaluation of dynamic effects of errors in the momentum exchange process, and the development of guidelines in selecting dynamic properties in the design of a capture device.

  17. Verification of nonlinear dynamic structural test results by combined image processing and acoustic analysis

    NASA Astrophysics Data System (ADS)

    Tene, Yair; Tene, Noam; Tene, G.

    1993-08-01

    An interactive data fusion methodology of video, audio, and nonlinear structural dynamic analysis for potential application in forensic engineering is presented. The methodology was developed and successfully demonstrated in the analysis of heavy transportable bridge collapse during preparation for testing. Multiple bridge elements failures were identified after the collapse, including fracture, cracks and rupture of high performance structural materials. Videotape recording by hand held camcorder was the only source of information about the collapse sequence. The interactive data fusion methodology resulted in extracting relevant information form the videotape and from dynamic nonlinear structural analysis, leading to full account of the sequence of events during the bridge collapse.

  18. Hydrodynamic body shape analysis and their impact on swimming performance.

    PubMed

    Li, Tian-Zeng; Zhan, Jie-Min

    2015-01-01

    This study presents the hydrodynamic characteristics of different adult male swimmer's body shape using computational fluid dynamics method. This simulation strategy is carried out by CFD fluent code with solving the 3D incompressible Navier-Stokes equations using the RNG k-ε turbulence closure. The water free surface is captured by the volume of fluid (VOF) method. A set of full body models, which is based on the anthropometrical characteristics of the most common male swimmers, is created by Computer Aided Industrial Design (CAID) software, Rhinoceros. The analysis of CFD results revealed that swimmer's body shape has a noticeable effect on the hydrodynamics performances. This explains why male swimmer with an inverted triangle body shape has good hydrodynamic characteristics for competitive swimming.

  19. 1-D Numerical Analysis of ABCC Engine Performance

    NASA Technical Reports Server (NTRS)

    Holden, Richard

    1999-01-01

    ABCC engine combines air breathing and rocket engine into a single engine to increase the specific impulse over an entire flight trajectory. Except for the heat source, the basic operation of the ABCC is similar to the basic operation of the RBCC engine. The ABCC is intended to have a higher specific impulse than the RBCC for single stage Earth to orbit vehicle. Computational fluid dynamics (CFD) is a useful tool for the analysis of complex transport processes in various components in ABCC propulsion system. The objective of the present research was to develop a transient 1-D numerical model using conservation of mass, linear momentum, and energy equations that could be used to predict flow behavior throughout a generic ABCC engine following a flight path. At specific points during the development of the 1-D numerical model a myriad of tests were performed to prove the program produced consistent, realistic numbers that follow compressible flow theory for various inlet conditions.

  20. Slow dynamics of a protein backbone in molecular dynamics simulation revealed by time-structure based independent component analysis

    SciTech Connect

    Naritomi, Yusuke; Fuchigami, Sotaro

    2013-12-07

    We recently proposed the method of time-structure based independent component analysis (tICA) to examine the slow dynamics involved in conformational fluctuations of a protein as estimated by molecular dynamics (MD) simulation [Y. Naritomi and S. Fuchigami, J. Chem. Phys. 134, 065101 (2011)]. Our previous study focused on domain motions of the protein and examined its dynamics by using rigid-body domain analysis and tICA. However, the protein changes its conformation not only through domain motions but also by various types of motions involving its backbone and side chains. Some of these motions might occur on a slow time scale: we hypothesize that if so, we could effectively detect and characterize them using tICA. In the present study, we investigated slow dynamics of the protein backbone using MD simulation and tICA. The selected target protein was lysine-, arginine-, ornithine-binding protein (LAO), which comprises two domains and undergoes large domain motions. MD simulation of LAO in explicit water was performed for 1 μs, and the obtained trajectory of C{sub α} atoms in the backbone was analyzed by tICA. This analysis successfully provided us with slow modes for LAO that represented either domain motions or local movements of the backbone. Further analysis elucidated the atomic details of the suggested local motions and confirmed that these motions truly occurred on the expected slow time scale.

  1. Slow dynamics of a protein backbone in molecular dynamics simulation revealed by time-structure based independent component analysis

    NASA Astrophysics Data System (ADS)

    Naritomi, Yusuke; Fuchigami, Sotaro

    2013-12-01

    We recently proposed the method of time-structure based independent component analysis (tICA) to examine the slow dynamics involved in conformational fluctuations of a protein as estimated by molecular dynamics (MD) simulation [Y. Naritomi and S. Fuchigami, J. Chem. Phys. 134, 065101 (2011)]. Our previous study focused on domain motions of the protein and examined its dynamics by using rigid-body domain analysis and tICA. However, the protein changes its conformation not only through domain motions but also by various types of motions involving its backbone and side chains. Some of these motions might occur on a slow time scale: we hypothesize that if so, we could effectively detect and characterize them using tICA. In the present study, we investigated slow dynamics of the protein backbone using MD simulation and tICA. The selected target protein was lysine-, arginine-, ornithine-binding protein (LAO), which comprises two domains and undergoes large domain motions. MD simulation of LAO in explicit water was performed for 1 μs, and the obtained trajectory of Cα atoms in the backbone was analyzed by tICA. This analysis successfully provided us with slow modes for LAO that represented either domain motions or local movements of the backbone. Further analysis elucidated the atomic details of the suggested local motions and confirmed that these motions truly occurred on the expected slow time scale.

  2. Using Dynamic Sensitivity Analysis to Assess Testability

    NASA Technical Reports Server (NTRS)

    Voas, Jeffrey; Morell, Larry; Miller, Keith

    1990-01-01

    This paper discusses sensitivity analysis and its relationship to random black box testing. Sensitivity analysis estimates the impact that a programming fault at a particular location would have on the program's input/output behavior. Locations that are relatively \\"insensitive" to faults can render random black box testing unlikely to uncover programming faults. Therefore, sensitivity analysis gives new insight when interpreting random black box testing results. Although sensitivity analysis is computationally intensive, it requires no oracle and no human intervention.

  3. Optimizing performance of hybrid FSO/RF networks in realistic dynamic scenarios

    NASA Astrophysics Data System (ADS)

    Llorca, Jaime; Desai, Aniket; Baskaran, Eswaran; Milner, Stuart; Davis, Christopher

    2005-08-01

    Hybrid Free Space Optical (FSO) and Radio Frequency (RF) networks promise highly available wireless broadband connectivity and quality of service (QoS), particularly suitable for emerging network applications involving extremely high data rate transmissions such as high quality video-on-demand and real-time surveillance. FSO links are prone to atmospheric obscuration (fog, clouds, snow, etc) and are difficult to align over long distances due the use of narrow laser beams and the effect of atmospheric turbulence. These problems can be mitigated by using adjunct directional RF links, which provide backup connectivity. In this paper, methodologies for modeling and simulation of hybrid FSO/RF networks are described. Individual link propagation models are derived using scattering theory, as well as experimental measurements. MATLAB is used to generate realistic atmospheric obscuration scenarios, including moving cloud layers at different altitudes. These scenarios are then imported into a network simulator (OPNET) to emulate mobile hybrid FSO/RF networks. This framework allows accurate analysis of the effects of node mobility, atmospheric obscuration and traffic demands on network performance, and precise evaluation of topology reconfiguration algorithms as they react to dynamic changes in the network. Results show how topology reconfiguration algorithms, together with enhancements to TCP/IP protocols which reduce the network response time, enable the network to rapidly detect and act upon link state changes in highly dynamic environments, ensuring optimized network performance and availability.

  4. The impact of interface bonding efficiency on high-burnup spent nuclear fuel dynamic performance

    DOE PAGES

    Jiang, Hao; Wang, Jy-An John; Wang, Hong

    2016-09-26

    Finite element analysis (FEA) was used to investigate the impact of interfacial bonding efficiency at pellet-pellet and pellet-clad interfaces of high-burnup (HBU) spent nuclear fuel (SNF) on system dynamic performance. Bending moments M were applied to FEA model to evaluate the system responses. From bending curvature, κ, flexural rigidity EI can be estimated as EI = M/κ. The FEA simulation results were benchmarked with experimental results from cyclic integrated reversal bending fatigue test (CIRFT) of HBR fuel rods. The consequence of interface debonding between fuel pellets and cladding is a redistribution of the loads carried by the fuel pellets tomore » the clad, which results in a reduction in composite rod system flexural rigidity. Furthermore, the interface bonding efficiency at the pellet-pellet and pellet-clad interfaces can significantly dictate the SNF system dynamic performance. With the consideration of interface bonding efficiency, the HBU SNF fuel property was estimated with CIRFT test data.« less

  5. Pavement performance monitoring using Dynamic Cone Penetrometer and Geogauge during construction

    NASA Astrophysics Data System (ADS)

    Ahsan, Ahmed Nawal

    Proper design life of road network system requires adequate quality control measures during the construction process to ensure proper material quality and sufficient strength in between the materials. Laboratory tests are often time consuming and sometimes, are not practical while the construction work is going on, in-situ techniques can efficiently evaluate the material properties through simple and less time consuming procedures. Dynamic Cone Penetrometer and Geogauge can play a vital role as an in-situ testing equipment because both have the potential to measure the change in material properties through field tests being performed in the field. Both in-situ techniques was not extensively used in North Texas area. Frequent use of these two equipment during the construction process can expedite the whole construction process because both are hand-held devices and can be conducted within a short amount of time, often in minutes. For this study, Dynamic Cone Penetrometer and Geogauge was used to assess the material properties from the tests performed on five construction sites of Horseshoe Project around Dallas, TX. Several points across the width of the pavement have been considered to perform these in-situ tests along with Nuclear Density Gauge test in two of these sites. A thorough analysis has been conducted for the material properties to be determined. Dynamic Cone Penetrometer and Geogauge both were consistent to measure the change in in-place material characteristics of the pavement materials. The design thickness of cement treated base layer where the tests were being performed was 6". DCP was efficient enough to detect the layer thickness up to a proximity of 0.5 inch and was also able to distinguish layer anomalies between the pavement layers. Cement stabilized base layer provided with a DCPI value which ranges from 0.5 mm/blow to 8 mm/blow whereas, DCPI values were observed to remain within a range of 2 mm/blow to 22 mm/ blow. For the top 6" cement

  6. Postfire seedling dynamics and performance in Pinus halepensis Mill. populations

    NASA Astrophysics Data System (ADS)

    Daskalakou, Evangelia N.; Thanos, Costas A.

    2010-09-01

    Postfire dynamics of Aleppo pine seedling density, survival and growth were assessed in five burned forests of Attica, Greece (Stamata, Villia, Avlona, Kapandriti and Agios Stefanos) through the establishment of permanent experimental plots. All emerging seedlings were tagged and their survival and growth monitored at regular intervals. Seedling density dynamics show an initial, steep increase (to maximum values 2.9-4.6 seedlings m -2) followed by a gradual decrease that levels off at the second and third postfire year (1.3-3.0 seedlings m -2); similarly, postfire seedling survival more or less stabilised at 30-50%, 2-3 years after fire. On the basis of density and mortality trends as well as relevant bibliographic data, it is predicted that very dense, mature forests (10.000 trees ha -1 or more) will be reinstated within 15-20 years. During the first 5-7 postfire years, seedling/sapling annual height followed linear trends with various yearly rates, ranging mostly between 8 and 15 cm (and 27-30 cm in two exceptional, fast growing cases). Within an individual growth season, seedling height dynamics were found to follow sigmoid curves with growth increment peaks in mid-spring. The time (on a monthly basis) of seedling emergence did not affect seedling growth or survival. On the other hand, for the first time under natural conditions, it has been shown that cotyledon number per seedling, an indirect measure of both seed size and initial photosynthetic capacity, significantly affected seedling survival but not growth. Seedlings bearing a higher number of cotyledons, presumably derived from larger seeds, showed greater survival at the end of the first postfire year than seedlings with fewer cotyledons. A postfire selective pressure, favouring large seed size, is postulated to counteract with a contrasting one, which favours small seed size, expressed during fire-free conditions.

  7. Dynamics analysis of space robot manipulator with joint clearance

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Bai, Zheng Feng

    2011-04-01

    A computational methodology for analysis of space robot manipulator systems, considering the effects of the clearances in the joint, is presented. The contact dynamics model in joint clearance is established using the nonlinear equivalent spring-damp model and the friction effect is considered using the Coulomb friction model. The space robot system dynamic equation of manipulator with clearance is established. Then the dynamics simulation is presented and the dynamics characteristics of robot manipulator with clearance are analyzed. This work provides a practical method to analyze the dynamics characteristics of space robot manipulator with joint clearance and improves the engineering application. The computational methodology can predict the effects of clearance on space robot manipulator preferably, which is the basis of space robot manipulator design, precision analysis and ground test.

  8. Structural dynamic analysis of the Space Shuttle Main Engine

    NASA Technical Reports Server (NTRS)

    Scott, L. P.; Jamison, G. T.; Mccutcheon, W. A.; Price, J. M.

    1981-01-01

    This structural dynamic analysis supports development of the SSME by evaluating components subjected to critical dynamic loads, identifying significant parameters, and evaluating solution methods. Engine operating parameters at both rated and full power levels are considered. Detailed structural dynamic analyses of operationally critical and life limited components support the assessment of engine design modifications and environmental changes. Engine system test results are utilized to verify analytic model simulations. The SSME main chamber injector assembly is an assembly of 600 injector elements which are called LOX posts. The overall LOX post analysis procedure is shown.

  9. Dynamic mechanical analysis: A practical introduction to techniques and applications

    SciTech Connect

    Menard, K.

    1999-03-01

    This introduction provides the chemist, chemical engineer, or materials scientists with a starting point to understand the applications of dynamic mechanical analysis, its workings, and its advantages and limitations. This book serves as a systematic study of manufacturing polymeric materials and components as well as for developing new materials. Contents include: introduction to dynamic mechanical analysis; basic rheological concepts: stress, strain, and flow; rheology basic: creep-recovery and stress relaxation; dynamic testing; time-temperature scans part 1: transitions in polymers; time and temperature studies part 2: thermosets; frequency scans; DMA applications to real problems: guidelines; and appendix: sample experiments for the DMA.

  10. Limiting performance of dynamic systems subject to random inputs

    NASA Technical Reports Server (NTRS)

    Pilkey, W. D.; Wang, B. P.

    1973-01-01

    The problem of determining the limiting performance characteristics of mechanical systems subject to random input is studied. A review is presented of the classical work in the optimal design of stochastic systems. Some recent results of stochastic optimal control theory are employed. The solution to the limiting performance problem is formulated in both the frequency and time domains. Both formulations require substantial, burdensome computations when applied to large scale systems.

  11. Three-dimensional dynamic response analysis of earth dams

    SciTech Connect

    Mejia, L.H.

    1981-01-01

    The purpose of the present work has been to develop numerical techniques for the three-dimensional dynamic analysis of earth and rockfill dams and to study the dynamic behavior of embankment dams in three dimensions. A computer program suitable for the three-dimensional dynamic response analysis of earth dams was used to back-calculate the dynamic material properties of Oroville Dam from the recorded response of the dam to the August 1, 1975 Oroville earthquake. The dynamic response characteristics of earth dams which exhibit considerable three-dimensional behavior have been studied and the applicability of two-dimensional analysis to the computation of the dynamic response of such structures has been evaluated. Additionally, the effects that the degree of discretization in the cross-valley direction has on the computed three-dimensional dynamic response of earth dams have been studied. A K/sub 2/max value of 170 was found to be representative of the in-situ dynamic characteristics of the Oroville gravels. The three-dimensional effects of canyon geometry on the dynamic response of dams in triangular canyons were found to depend on the crest length to height ratio, L/H, of the dam. For dams with L/H greater than 7, these effects are small. The dynamic characteristics of these dams can, therefore, be simulated reasonably well using two-dimensional analyses. However, 2-D analyses cannot simulate correctly the dynamic response of dams in narrower canyons since the effects of canyon geometry for these dams are very pronounced.

  12. Performance analysis of robust road sign identification

    NASA Astrophysics Data System (ADS)

    Ali, Nursabillilah M.; Mustafah, Y. M.; Rashid, N. K. A. M.

    2013-12-01

    This study describes performance analysis of a robust system for road sign identification that incorporated two stages of different algorithms. The proposed algorithms consist of HSV color filtering and PCA techniques respectively in detection and recognition stages. The proposed algorithms are able to detect the three standard types of colored images namely Red, Yellow and Blue. The hypothesis of the study is that road sign images can be used to detect and identify signs that are involved with the existence of occlusions and rotational changes. PCA is known as feature extraction technique that reduces dimensional size. The sign image can be easily recognized and identified by the PCA method as is has been used in many application areas. Based on the experimental result, it shows that the HSV is robust in road sign detection with minimum of 88% and 77% successful rate for non-partial and partial occlusions images. For successful recognition rates using PCA can be achieved in the range of 94-98%. The occurrences of all classes are recognized successfully is between 5% and 10% level of occlusions.

  13. Model Performance Evaluation and Scenario Analysis (MPESA) Tutorial

    EPA Science Inventory

    This tool consists of two parts: model performance evaluation and scenario analysis (MPESA). The model performance evaluation consists of two components: model performance evaluation metrics and model diagnostics. These metrics provides modelers with statistical goodness-of-fit m...

  14. Static and dynamic performances of refrigerant-lubricated foil bearings

    NASA Astrophysics Data System (ADS)

    Bouchehit, B.; Bou-Saïd, B.; Garcia, M.

    2016-08-01

    Gas bearings are successfully used over a large panel of turbo-machineries. Some of these systems run in controlled environments such as refrigerating gas. We present in this paper a theoretical and numerical model which consider the vapor/liquid lubricant transition, the laminar/turbulent flow transition and both temperature and viscosity 3D variations in the fluid and the solids for both static and dynamic situations. The foil deflection is considered using the Heshmat's approach. This model involves: the resolution of the generalized Reynolds equation for compressible fluids with 3D variable viscosity, the description of the turbulence effects by the phenomenological approach of Elrod, using a 3D eddy viscosity field, the resolution of a non-linear equation of state for the lubricant, able to describe the vapor/liquid transition and a local thermal approach to obtain a 3D estimation of the fluid temperature, thanks to the thin-film energy equation and an actualisation of the film thickness. The thermal effects in solids are also taken into account. Both static and dynamic behaviours of GFBs are analysed.

  15. A Wigner Distribution Analysis of Scattering Dynamics

    NASA Astrophysics Data System (ADS)

    Weeks, David; Lacy, Brent

    2009-04-01

    Using the time dependent Channel Packet Method (CPM),ootnotetextD.E.Weeks, T.A.Niday, S.H.Yang, J Chem Phys. 125, 164301 (2006). a Fourier transformation of the correlation function between evolving wave packets is used to compute scattering matrix elements. The correlation function can also be used to compute a Wigner distribution as a function of time and energy. This scattering Wigner distribution is then used to investigate times at which various energetic contributions to the scattering matrix are made during a molecular collision. We compute scattering Wigner distributions for a variety of molecular systems and use them to characterize the associated molecular dynamics. In particular, the square well provides a simple and easily modified potential to study the relationship between the scattering Wigner distribution and wave packet dynamics. Additional systems that are being studied include the collinear H + H2 molecular reaction, and the non-adiabatic B + H2 molecular collision.

  16. Network analysis of human heartbeat dynamics

    NASA Astrophysics Data System (ADS)

    Shao, Zhi-Gang

    2010-02-01

    We construct the complex networks of human heartbeat dynamics and investigate their statistical properties, using the visibility algorithm proposed by Lacasa and co-workers [Proc. Natl. Acad. Sci. U.S.A. 105, 4972 (2008)]. Our results show that the associated networks for the time series of heartbeat interval are always scale-free, high clustering, hierarchy, and assortative mixing. In particular, the assortative coefficient of associated networks could distinguish between healthy subjects and patients with congestive heart failure.

  17. Structure and Topology Dynamics of Hyper-Frequency Networks during Rest and Auditory Oddball Performance.

    PubMed

    Müller, Viktor; Perdikis, Dionysios; von Oertzen, Timo; Sleimen-Malkoun, Rita; Jirsa, Viktor; Lindenberger, Ulman

    2016-01-01

    Resting-state and task-related recordings are characterized by oscillatory brain activity and widely distributed networks of synchronized oscillatory circuits. Electroencephalographic recordings (EEG) were used to assess network structure and network dynamics during resting state with eyes open and closed, and auditory oddball performance through phase synchronization between EEG channels. For this assessment, we constructed a hyper-frequency network (HFN) based on within- and cross-frequency coupling (WFC and CFC, respectively) at 10 oscillation frequencies ranging between 2 and 20 Hz. We found that CFC generally differentiates between task conditions better than WFC. CFC was the highest during resting state with eyes open. Using a graph-theoretical approach (GTA), we found that HFNs possess small-world network (SWN) topology with a slight tendency to random network characteristics. Moreover, analysis of the temporal fluctuations of HFNs revealed specific network topology dynamics (NTD), i.e., temporal changes of different graph-theoretical measures such as strength, clustering coefficient, characteristic path length (CPL), local, and global efficiency determined for HFNs at different time windows. The different topology metrics showed significant differences between conditions in the mean and standard deviation of these metrics both across time and nodes. In addition, using an artificial neural network approach, we found stimulus-related dynamics that varied across the different network topology metrics. We conclude that functional connectivity dynamics (FCD), or NTD, which was found using the HFN approach during rest and stimulus processing, reflects temporal and topological changes in the functional organization and reorganization of neuronal cell assemblies.

  18. Structure and Topology Dynamics of Hyper-Frequency Networks during Rest and Auditory Oddball Performance

    PubMed Central

    Müller, Viktor; Perdikis, Dionysios; von Oertzen, Timo; Sleimen-Malkoun, Rita; Jirsa, Viktor; Lindenberger, Ulman

    2016-01-01

    Resting-state and task-related recordings are characterized by oscillatory brain activity and widely distributed networks of synchronized oscillatory circuits. Electroencephalographic recordings (EEG) were used to assess network structure and network dynamics during resting state with eyes open and closed, and auditory oddball performance through phase synchronization between EEG channels. For this assessment, we constructed a hyper-frequency network (HFN) based on within- and cross-frequency coupling (WFC and CFC, respectively) at 10 oscillation frequencies ranging between 2 and 20 Hz. We found that CFC generally differentiates between task conditions better than WFC. CFC was the highest during resting state with eyes open. Using a graph-theoretical approach (GTA), we found that HFNs possess small-world network (SWN) topology with a slight tendency to random network characteristics. Moreover, analysis of the temporal fluctuations of HFNs revealed specific network topology dynamics (NTD), i.e., temporal changes of different graph-theoretical measures such as strength, clustering coefficient, characteristic path length (CPL), local, and global efficiency determined for HFNs at different time windows. The different topology metrics showed significant differences between conditions in the mean and standard deviation of these metrics both across time and nodes. In addition, using an artificial neural network approach, we found stimulus-related dynamics that varied across the different network topology metrics. We conclude that functional connectivity dynamics (FCD), or NTD, which was found using the HFN approach during rest and stimulus processing, reflects temporal and topological changes in the functional organization and reorganization of neuronal cell assemblies. PMID:27799906

  19. Gigaflop performance on a CRAY-2: Multitasking a computational fluid dynamics application

    NASA Technical Reports Server (NTRS)

    Tennille, Geoffrey M.; Overman, Andrea L.; Lambiotte, Jules J.; Streett, Craig L.

    1991-01-01

    The methodology is described for converting a large, long-running applications code that executed on a single processor of a CRAY-2 supercomputer to a version that executed efficiently on multiple processors. Although the conversion of every application is different, a discussion of the types of modification used to achieve gigaflop performance is included to assist others in the parallelization of applications for CRAY computers, especially those that were developed for other computers. An existing application, from the discipline of computational fluid dynamics, that had utilized over 2000 hrs of CPU time on CRAY-2 during the previous year was chosen as a test case to study the effectiveness of multitasking on a CRAY-2. The nature of dominant calculations within the application indicated that a sustained computational rate of 1 billion floating-point operations per second, or 1 gigaflop, might be achieved. The code was first analyzed and modified for optimal performance on a single processor in a batch environment. After optimal performance on a single CPU was achieved, the code was modified to use multiple processors in a dedicated environment. The results of these two efforts were merged into a single code that had a sustained computational rate of over 1 gigaflop on a CRAY-2. Timings and analysis of performance are given for both single- and multiple-processor runs.

  20. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production

    PubMed Central

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role. PMID:26217252

  1. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production.

    PubMed

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role.

  2. Eucb: A C++ program for molecular dynamics trajectory analysis

    NASA Astrophysics Data System (ADS)

    Tsoulos, Ioannis G.; Stavrakoudis, Athanassios

    2011-03-01

    Eucb is a standalone program for geometrical analysis of molecular dynamics trajectories of protein systems. The program is written in GNU C++ and it can be installed in any operating system running a C++ compiler. The program performs its analytical tasks based on user supplied keywords. The source code is freely available from http://stavrakoudis.econ.uoi.gr/eucb under LGPL 3 license. Program summaryProgram title:Eucb Catalogue identifier: AEIC_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIC_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 31 169 No. of bytes in distributed program, including test data, etc.: 297 364 Distribution format: tar.gz Programming language: GNU C++ Computer: The tool is designed and tested on GNU/Linux systems Operating system: Unix/Linux systems RAM: 2 MB Supplementary material: Sample data files are available Classification: 3 Nature of problem: Analysis of molecular dynamics trajectories. Solution method: The program finds all possible interactions according to input files and the user instructions. Then it reads all the trajectory frames and finds those frames in which these interactions occur, under certain geometrical criteria. This is a blind search, without a priori knowledge if a certain interaction occurs or not. The program exports time series of these quantities (distance, angles, etc.) and appropriate descriptive statistics. Running time: Depends on the input data and the required options.

  3. Effect of Static and Dynamic Stretching on the Diurnal Variations of Jump Performance in Soccer Players

    PubMed Central

    Chtourou, Hamdi; Aloui, Asma; Hammouda, Omar; Chaouachi, Anis; Chamari, Karim; Souissi, Nizar

    2013-01-01

    Purpose The present study addressed the lack of data on the effect of different types of stretching on diurnal variations in vertical jump height - i.e., squat-jump (SJ) and countermovement-jump (CMJ). We hypothesized that dynamic stretching could affect the diurnal variations of jump height by producing a greater increase in short-term maximal performance in the morning than the evening through increasing core temperature at this time-of-day. Methods Twenty male soccer players (age, 18.6±1.3 yrs; height, 174.6±3.8 cm; body-mass, 71.1±8.6 kg; mean ± SD) completed the SJ and CMJ tests either after static stretching, dynamic stretching or no-stretching protocols at two times of day, 07:00 h and 17:00 h, with a minimum of 48 hours between testing sessions. One minute after warming-up for 5 minutes by light jogging and performing one of the three stretching protocols (i.e., static stretching, dynamic stretching or no-stretching) for 8 minutes, each subject completed the SJ and CMJ tests. Jumping heights were recorded and analyzed using a two-way analysis of variance with repeated measures (3 [stretching]×2 [time-of-day]). Results The SJ and CMJ heights were significantly higher at 17:00 than 07:00 h (p<0.01) after the no-stretching protocol. These daily variations disappeared (i.e., the diurnal gain decreased from 4.2±2.81% (p<0.01) to 1.81±4.39% (not-significant) for SJ and from 3.99±3.43% (p<0.01) to 1.51±3.83% (not-significant) for CMJ) after dynamic stretching due to greater increases in SJ and CMJ heights in the morning than the evening (8.4±6.36% vs. 4.4±2.64%, p<0.05 for SJ and 10.61±5.49% vs. 6.03±3.14%, p<0.05 for CMJ). However, no significant effect of static stretching on the diurnal variations of SJ and CMJ heights was observed. Conclusion Dynamic stretching affects the typical diurnal variations of SJ and CMJ and helps to counteract the lower morning values in vertical jump height. PMID:23940589

  4. Performance of laser inter-satellite links with dynamic beam waist adjustment.

    PubMed

    Song, Tianyu; Wang, Qian; Wu, Ming-Wei; Kam, Pooi-Yuen

    2016-05-30

    In this paper, we propose the idea of dynamic beam waist adjustment for laser inter-satellite communications, and study the performance of this dynamic-beam scheme. The beam waist adjustment is based on continuous detection of the instantaneous pointing error angle, which is performed at the transmitter side. Using a square to approximate the circular detector region, we obtain a closed-form expression for calculating the proportion of power that can be collected by the receiver aperture, and derive a simple algebraic solution for the optimum dynamic beam waist. Due to its simple form, the dynamic beam waist value can be computed in real time at the transmitter, and therefore, the adjustment is practically implementable. It is shown that the performance of laser inter-satellite links with dynamic beam waist is better than that with fixed beam waist.

  5. Are acute effects of maximal dynamic contractions on upper-body ballistic performance load specific?

    PubMed

    Markovic, Goran; Simek, Sanja; Bradic, Asim

    2008-11-01

    This study investigated the acute effects of upper-body maximal dynamic contractions on maximal throwing speed with 0.55- and 4-kg medicine balls. It was hypothesized that heavy preloading would transiently improve throwing performance only when overcoming the heavier of the two loads. Twenty-three male volunteers were randomly allocated into experimental (n = 11) and control (n = 12) groups. Both groups performed initial and final seated medicine ball throws from the chest, and the maximal medicine ball speed was measured by means of a radar gun. Between the two measurements, the control group rested passively for 15 minutes, and the experimental group performed three sets of three-repetition maximum bench presses. For the 0.55-kg load, a 2 x 2 repeated-measures analysis of variance revealed no significant effect of time x group interaction (p = 0.22), as well as no significant time (p = 0.22) or group (p = 0.72) effects. In contrast, for the 4-kg load, a significant time x group interaction (p = 0.004) and a significant time (p = 0.035) but not group (p = 0.77) effect were observed. Analysis of simple main effects revealed that the experimental group significantly (8.3%; p < 0.01) improved maximal throwing speed with the 4-kg load. These results support our research hypothesis and suggest that the acute effects of heavy preloading on upper-body ballistic performance might be load specific. In a practical sense, our findings suggest that the use of upper-body heavy resistance exercise before ballistic throwing movements against moderate external loads might be an efficient training strategy for improving an athlete's upper-body explosive performance.

  6. High-performance dynamic quantum clustering on graphics processors

    SciTech Connect

    Wittek, Peter

    2013-01-15

    Clustering methods in machine learning may benefit from borrowing metaphors from physics. Dynamic quantum clustering associates a Gaussian wave packet with the multidimensional data points and regards them as eigenfunctions of the Schroedinger equation. The clustering structure emerges by letting the system evolve and the visual nature of the algorithm has been shown to be useful in a range of applications. Furthermore, the method only uses matrix operations, which readily lend themselves to parallelization. In this paper, we develop an implementation on graphics hardware and investigate how this approach can accelerate the computations. We achieve a speedup of up to two magnitudes over a multicore CPU implementation, which proves that quantum-like methods and acceleration by graphics processing units have a great relevance to machine learning.

  7. Corticostriatal dynamics during learning and performance of a neuroprosthetic task.

    PubMed

    Koralek, Aaron C; Long, John D; Costa, Rui M; Carmena, Jose M

    2010-01-01

    Corticostriatal dynamics exhibit gross alterations over the course of natural motor learning, yet little is known about the role they play in neuroprosthetic tasks. We therefore investigated interactions between the striatum and primary motor cortex while rats learned to control a brain-machine interface. Striatal firing rates increased greatly from early to late in learning, suggesting that the striatum underlies similar functions in both natural and neuroprosthetic motor learning. In addition, spike-field coherence between neurons in primary motor cortex and local field potentials in the striatum increased greatly in the alpha band in late learning relative to early learning, suggesting the development of functional interactions in corticostriatal networks over the course of learning.

  8. High-performance dynamic quantum clustering on graphics processors

    NASA Astrophysics Data System (ADS)

    Wittek, Peter

    2013-01-01

    Clustering methods in machine learning may benefit from borrowing metaphors from physics. Dynamic quantum clustering associates a Gaussian wave packet with the multidimensional data points and regards them as eigenfunctions of the Schrödinger equation. The clustering structure emerges by letting the system evolve and the visual nature of the algorithm has been shown to be useful in a range of applications. Furthermore, the method only uses matrix operations, which readily lend themselves to parallelization. In this paper, we develop an implementation on graphics hardware and investigate how this approach can accelerate the computations. We achieve a speedup of up to two magnitudes over a multicore CPU implementation, which proves that quantum-like methods and acceleration by graphics processing units have a great relevance to machine learning.

  9. Nonlinear Dynamic Inversion Baseline Control Law: Architecture and Performance Predictions

    NASA Technical Reports Server (NTRS)

    Miller, Christopher J.

    2011-01-01

    A model reference dynamic inversion control law has been developed to provide a baseline control law for research into adaptive elements and other advanced flight control law components. This controller has been implemented and tested in a hardware-in-the-loop simulation; the simulation results show excellent handling qualities throughout the limited flight envelope. A simple angular momentum formulation was chosen because it can be included in the stability proofs for many basic adaptive theories, such as model reference adaptive control. Many design choices and implementation details reflect the requirements placed on the system by the nonlinear flight environment and the desire to keep the system as basic as possible to simplify the addition of the adaptive elements. Those design choices are explained, along with their predicted impact on the handling qualities.

  10. Tooth modification and dynamic performance of the cycloidal drive

    NASA Astrophysics Data System (ADS)

    Ren, Zhong-Yi; Mao, Shi-Min; Guo, Wen-Chao; Guo, Zheng

    2017-02-01

    A new method of cycloid disc tooth modification is presented in this paper. Its main idea is to design the modification clearance curves to adapt to different modification targets. A detailed procedure of the new modification clearance curve, which can be defined by adjusting the position of 5 key points is developed. Numerical experiments are carried out to verify the effectiveness of the new method. A Multi-DOF nonlinear dynamic model of cycloidal speed reducer is established, then the cycloid disc rotational displacement and rotational velocity versus time of different modification clearance are solved by the Runge-kutta numerical method. The results show that this method can improve the carrying capability of cycloidal drive, eliminate noise and vibration and develop the transmission accuracy.

  11. Prediction of Combustion-Driven Dynamic Instability for High Performance Gas Turbine Combustors: Part I

    DTIC Science & Technology

    2001-06-01

    Hsiao, G., Pandalai, R., Hura, H., and Mongia , H. C., "Chropulsio a p e -Vol. o mbustor, 1998. " Combustion Dynamic Modeling for Gas Turbine...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO 11162 TITLE: Predicton of Combustion -Driven Dynamic Instability for...UNCLASSIFIED , Click here to view PowerPoint presentation; Press Esc to exit ,: Prediction of Combustion -Driven Dynamic Instability For High Performance Gas

  12. NEXT Performance Curve Analysis and Validation

    NASA Technical Reports Server (NTRS)

    Saripalli, Pratik; Cardiff, Eric; Englander, Jacob

    2016-01-01

    Performance curves of the NEXT thruster are highly important in determining the thruster's ability in performing towards mission-specific goals. New performance curves are proposed and examined here. The Evolutionary Mission Trajectory Generator (EMTG) is used to verify variations in mission solutions based on both available thruster curves and the new curves generated. Furthermore, variations in BOL and EOL curves are also examined. Mission design results shown here validate the use of EMTG and the new performance curves.

  13. Dynamic Experiments and Constitutive Model Performance for Polycarbonate

    DTIC Science & Technology

    2014-07-01

    together to dictate deformation response to subsequent failure. The physical processes and evolution are complicated and may be difficult to access...experimentally. Because of the complex processes present during a ballistic impact event, it is often difficult to identify the armor or material...identify key interactions (e.g., properties, wave propagation, interfaces, geometry, composition, processing ) that pilot valued protection performance

  14. Dynamic Social Networks in High Performance Football Coaching

    ERIC Educational Resources Information Center

    Occhino, Joseph; Mallett, Cliff; Rynne, Steven

    2013-01-01

    Background: Sports coaching is largely a social activity where engagement with athletes and support staff can enhance the experiences for all involved. This paper examines how high performance football coaches develop knowledge through their interactions with others within a social learning theory framework. Purpose: The key purpose of this study…

  15. Sequential Structural and Fluid Dynamics Analysis of Balloon-Expandable Coronary Stents: A Multivariable Statistical Analysis.

    PubMed

    Martin, David; Boyle, Fergal

    2015-09-01

    Several clinical studies have identified a strong correlation between neointimal hyperplasia following coronary stent deployment and both stent-induced arterial injury and altered vessel hemodynamics. As such, the sequential structural and fluid dynamics analysis of balloon-expandable stent deployment should provide a comprehensive indication of stent performance. Despite this observation, very few numerical studies of balloon-expandable coronary stents have considered both the mechanical and hemodynamic impact of stent deployment. Furthermore, in the few studies that have considered both phenomena, only a small number of stents have been considered. In this study, a sequential structural and fluid dynamics analysis methodology was employed to compare both the mechanical and hemodynamic impact of six balloon-expandable coronary stents. To investigate the relationship between stent design and performance, several common stent design properties were then identified and the dependence between these properties and both the mechanical and hemodynamic variables of interest was evaluated using statistical measures of correlation. Following the completion of the numerical analyses, stent strut thickness was identified as the only common design property that demonstrated a strong dependence with either the mean equivalent stress predicted in the artery wall or the mean relative residence time predicted on the luminal surface of the artery. These results corroborate the findings of the large-scale ISAR-STEREO clinical studies and highlight the crucial role of strut thickness in coronary stent design. The sequential structural and fluid dynamics analysis methodology and the multivariable statistical treatment of the results described in this study should prove useful in the design of future balloon-expandable coronary stents.

  16. Lifespan Differences in Nonlinear Dynamics during Rest and Auditory Oddball Performance

    ERIC Educational Resources Information Center

    Muller, Viktor; Lindenberger, Ulman

    2012-01-01

    Electroencephalographic recordings (EEG) were used to assess age-associated differences in nonlinear brain dynamics during both rest and auditory oddball performance in children aged 9.0-12.8 years, younger adults, and older adults. We computed nonlinear coupling dynamics and dimensional complexity, and also determined spectral alpha power as an…

  17. The Developmental Dynamics of Task-Avoidant Behavior and Math Performance in Kindergarten and Elementary School

    ERIC Educational Resources Information Center

    Hirvonen, Riikka; Tolvanen, Asko; Aunola, Kaisa; Nurmi, Jari-Erik

    2012-01-01

    Besides cognitive factors, children's learning at school may be influenced by more dynamic phenomena, such as motivation and achievement-related task-avoidant behavior. The present study examined the developmental dynamics of task-avoidant behavior and math performance from kindergarten to Grade 4. A total of 225 children were tested for their…

  18. Analytical analysis of particle-core dynamics

    SciTech Connect

    Batygin, Yuri K

    2010-01-01

    Particle-core interaction is a well-developed model of halo formation in high-intensity beams. In this paper, we present an analytical solution for averaged, single particle dynamics, around a uniformly charged beam. The problem is analyzed through a sequence of canonical transformations of the Hamiltonian, which describes nonlinear particle oscillations. A closed form expression for maximum particle deviation from the axis is obtained. The results of this study are in good agreement with numerical simulations and with previously obtained data.

  19. Numerical model of solar dynamic radiator for parametric analysis

    NASA Technical Reports Server (NTRS)

    Rhatigan, Jennifer L.

    1989-01-01

    Growth power requirements for Space Station Freedom will be met through addition of 25 kW solar dynamic (SD) power modules. The SD module rejects waste heat from the power conversion cycle to space through a pumped-loop, multi-panel, deployable radiator. The baseline radiator configuration was defined during the Space Station conceptual design phase and is a function of the state point and heat rejection requirements of the power conversion unit. Requirements determined by the overall station design such as mass, system redundancy, micrometeoroid and space debris impact survivability, launch packaging, costs, and thermal and structural interaction with other station components have also been design drivers for the radiator configuration. Extensive thermal and power cycle modeling capabilities have been developed which are powerful tools in Station design and analysis, but which prove cumbersome and costly for simple component preliminary design studies. In order to aid in refining the SD radiator to the mature design stage, a simple and flexible numerical model was developed. The model simulates heat transfer and fluid flow performance of the radiator and calculates area mass and impact survivability for many combinations of flow tube and panel configurations, fluid and material properties, and environmental and cycle variations. A brief description and discussion of the numerical model, it's capabilities and limitations, and results of the parametric studies performed is presented.

  20. IPAC-Inlet Performance Analysis Code

    NASA Technical Reports Server (NTRS)

    Barnhart, Paul J.

    1997-01-01

    A series of analyses have been developed which permit the calculation of the performance of common inlet designs. The methods presented are useful for determining the inlet weight flows, total pressure recovery, and aerodynamic drag coefficients for given inlet geometric designs. Limited geometric input data is required to use this inlet performance prediction methodology. The analyses presented here may also be used to perform inlet preliminary design studies. The calculated inlet performance parameters may be used in subsequent engine cycle analyses or installed engine performance calculations for existing uninstalled engine data.

  1. Robust Hurwitz Stability and Performance Analysis of H-Infinity Controlled Forward-Velocity Dynamics of UAVs in Close Formation Flight Using Bounded Phase Conditions in a Kharitonov Framework

    NASA Astrophysics Data System (ADS)

    Johnson, Y.; Dasgupta, S.

    2014-07-01

    Multiple unmanned aerial vehicle (UAV) control in formation flight is comparatively a new research area in the field of aerospace engineering. In the proposed work, robust control techniques are implemented to maintain a fixed relative distance in horizontal and vertical direction with uniform pitch orientation in an uncertain leader-follower pattern of close formation flight platform. The forward velocity dynamics is of focal interest in this paper. H-infinity controllers are designed for leader control and its tracking. The robustness of the H-infinity controller is validated with Kharitonov related bounded phase conditions by forming interval polynomials.

  2. Overview of MSFC's Applied Fluid Dynamics Analysis Group Activities

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Griffin, Lisa; Williams, Robert

    2003-01-01

    TD64, the Applied Fluid Dynamics Analysis Group, is one of several groups with high-fidelity fluids design and analysis expertise in the Space Transportation Directorate at Marshall Space Flight Center (MSFC). TD64 assists personnel working on other programs. The group participates in projects in the following areas: turbomachinery activities, nozzle activities, combustion devices, and the Columbia accident investigation.

  3. Automatic A-set selection for dynamics analysis

    NASA Technical Reports Server (NTRS)

    Allen, Tom

    1993-01-01

    A method for selecting optimum NASTRAN analysis set degrees of freedom for the dynamic eigenvalue problem is described. Theoretical development of the Guyan reduction procedure on which the method is based is first summarized. The algorithm used to select the analysis set degrees of freedom is then developed. Two example problems are provided to demonstrate the accuracy of the algorithm.

  4. Bootstrap Standard Error Estimates in Dynamic Factor Analysis

    ERIC Educational Resources Information Center

    Zhang, Guangjian; Browne, Michael W.

    2010-01-01

    Dynamic factor analysis summarizes changes in scores on a battery of manifest variables over repeated measurements in terms of a time series in a substantially smaller number of latent factors. Algebraic formulae for standard errors of parameter estimates are more difficult to obtain than in the usual intersubject factor analysis because of the…

  5. Conducting Qualitative Data Analysis: Managing Dynamic Tensions within

    ERIC Educational Resources Information Center

    Chenail, Ronald J.

    2012-01-01

    In the third of a series of "how-to" essays on conducting qualitative data analysis, Ron Chenail examines the dynamic tensions within the process of qualitative data analysis that qualitative researchers must manage in order to produce credible and creative results. These tensions include (a) the qualities of the data and the qualitative data…

  6. Dynamic metabolic flux analysis of plant cell wall synthesis.

    PubMed

    Chen, Xuewen; Alonso, Ana P; Shachar-Hill, Yair

    2013-07-01

    The regulation of plant cell wall synthesis pathways remains poorly understood. This has become a bottleneck in designing bioenergy crops. The goal of this study was to analyze the regulation of plant cell wall precursor metabolism using metabolic flux analysis based on dynamic labeling experiments. Arabidopsis T87 cells were cultured heterotrophically with (13)C labeled sucrose. The time course of ¹³C labeling patterns in cell wall precursors and related sugar phosphates was monitored using liquid chromatography tandem mass spectrometry until steady state labeling was reached. A kinetic model based on mass action reaction mechanisms was developed to simulate the carbon flow in the cell wall synthesis network. The kinetic parameters of the model were determined by fitting the model to the labeling time course data, cell wall composition, and synthesis rates. A metabolic control analysis was performed to predict metabolic regulations that may improve plant biomass composition for biofuel production. Our results describe the routes and rates of carbon flow from sucrose to cell wall precursors. We found that sucrose invertase is responsible for the entry of sucrose into metabolism and UDP-glucose-4-epimerase plays a dominant role in UDP-Gal synthesis in heterotrophic Aradidopsis cells under aerobic conditions. We also predicted reactions that exert strong regulatory influence over carbon flow to cell wall synthesis and its composition.

  7. Analysis of proteome dynamics in the mouse brain

    PubMed Central

    Price, John C.; Guan, Shenheng; Burlingame, Alma; Prusiner, Stanley B.; Ghaemmaghami, Sina

    2010-01-01

    Advances in systems biology have allowed for global analyses of mRNA and protein expression, but large-scale studies of protein dynamics and turnover have not been conducted in vivo. Protein turnover is an important metabolic and regulatory mechanism in establishing proteome homeostasis, impacting many physiological and pathological processes. Here, we have used organism-wide isotopic labeling to measure the turnover rates of ~2,500 proteins in multiple mouse tissues, spanning four orders of magnitude. Through comparison of the brain with the liver and blood, we show that within the respective tissues, proteins performing similar functions often have similar turnover rates. Proteins in the brain have significantly slower turnover (average lifetime of 9.0 d) compared with those of the liver (3.0 d) and blood (3.5 d). Within some organelles (such as mitochondria), proteins have a narrow range of lifetimes, suggesting a synchronized turnover mechanism. Protein subunits within complexes of variable composition have a wide range of lifetimes, whereas those within well-defined complexes turn over in a coordinated manner. Together, the data represent the most comprehensive in vivo analysis of mammalian proteome turnover to date. The developed methodology can be adapted to assess in vivo proteome homeostasis in any model organism that will tolerate a labeled diet and may be particularly useful in the analysis of neurodegenerative diseases in vivo. PMID:20699386

  8. Efficient sensitivity analysis method for chaotic dynamical systems

    SciTech Connect

    Liao, Haitao

    2016-05-15

    The direct differentiation and improved least squares shadowing methods are both developed for accurately and efficiently calculating the sensitivity coefficients of time averaged quantities for chaotic dynamical systems. The key idea is to recast the time averaged integration term in the form of differential equation before applying the sensitivity analysis method. An additional constraint-based equation which forms the augmented equations of motion is proposed to calculate the time averaged integration variable and the sensitivity coefficients are obtained as a result of solving the augmented differential equations. The application of the least squares shadowing formulation to the augmented equations results in an explicit expression for the sensitivity coefficient which is dependent on the final state of the Lagrange multipliers. The LU factorization technique to calculate the Lagrange multipliers leads to a better performance for the convergence problem and the computational expense. Numerical experiments on a set of problems selected from the literature are presented to illustrate the developed methods. The numerical results demonstrate the correctness and effectiveness of the present approaches and some short impulsive sensitivity coefficients are observed by using the direct differentiation sensitivity analysis method.

  9. MDAnalysis: a toolkit for the analysis of molecular dynamics simulations.

    PubMed

    Michaud-Agrawal, Naveen; Denning, Elizabeth J; Woolf, Thomas B; Beckstein, Oliver

    2011-07-30

    MDAnalysis is an object-oriented library for structural and temporal analysis of molecular dynamics (MD) simulation trajectories and individual protein structures. It is written in the Python language with some performance-critical code in C. It uses the powerful NumPy package to expose trajectory data as fast and efficient NumPy arrays. It has been tested on systems of millions of particles. Many common file formats of simulation packages including CHARMM, Gromacs, Amber, and NAMD and the Protein Data Bank format can be read and written. Atoms can be selected with a syntax similar to CHARMM's powerful selection commands. MDAnalysis enables both novice and experienced programmers to rapidly write their own analytical tools and access data stored in trajectories in an easily accessible manner that facilitates interactive explorative analysis. MDAnalysis has been tested on and works for most Unix-based platforms such as Linux and Mac OS X. It is freely available under the GNU General Public License from http://mdanalysis.googlecode.com.

  10. A fractal approach to dynamic inference and distribution analysis.

    PubMed

    van Rooij, Marieke M J W; Nash, Bertha A; Rajaraman, Srinivasan; Holden, John G

    2013-01-01

    Event-distributions inform scientists about the variability and dispersion of repeated measurements. This dispersion can be understood from a complex systems perspective, and quantified in terms of fractal geometry. The key premise is that a distribution's shape reveals information about the governing dynamics of the system that gave rise to the distribution. Two categories of characteristic dynamics are distinguished: additive systems governed by component-dominant dynamics and multiplicative or interdependent systems governed by interaction-dominant dynamics. A logic by which systems governed by interaction-dominant dynamics are expected to yield mixtures of lognormal and inverse power-law samples is discussed. These mixtures are described by a so-called cocktail model of response times derived from human cognitive performances. The overarching goals of this article are twofold: First, to offer readers an introduction to this theoretical perspective and second, to offer an overview of the related statistical methods.

  11. Startle auditory stimuli enhance the performance of fast dynamic contractions.

    PubMed

    Fernandez-Del-Olmo, Miguel; Río-Rodríguez, Dan; Iglesias-Soler, Eliseo; Acero, Rafael M

    2014-01-01

    Fast reaction times and the ability to develop a high rate of force development (RFD) are crucial for sports performance. However, little is known regarding the relationship between these parameters. The aim of this study was to investigate the effects of auditory stimuli of different intensities on the performance of a concentric bench-press exercise. Concentric bench-presses were performed by thirteen trained subjects in response to three different conditions: a visual stimulus (VS); a visual stimulus accompanied by a non-startle auditory stimulus (AS); and a visual stimulus accompanied by a startle auditory stimulus (SS). Peak RFD, peak velocity, onset movement, movement duration and electromyography from pectoralis and tricep muscles were recorded. The SS condition induced an increase in the RFD and peak velocity and a reduction in the movement onset and duration, in comparison with the VS and AS condition. The onset activation of the pectoralis and tricep muscles was shorter for the SS than for the VS and AS conditions. These findings point out to specific enhancement effects of loud auditory stimulation on the rate of force development. This is of relevance since startle stimuli could be used to explore neural adaptations to resistance training.

  12. Startle Auditory Stimuli Enhance the Performance of Fast Dynamic Contractions

    PubMed Central

    Fernandez-Del-Olmo, Miguel; Río-Rodríguez, Dan; Iglesias-Soler, Eliseo; Acero, Rafael M.

    2014-01-01

    Fast reaction times and the ability to develop a high rate of force development (RFD) are crucial for sports performance. However, little is known regarding the relationship between these parameters. The aim of this study was to investigate the effects of auditory stimuli of different intensities on the performance of a concentric bench-press exercise. Concentric bench-presses were performed by thirteen trained subjects in response to three different conditions: a visual stimulus (VS); a visual stimulus accompanied by a non-startle auditory stimulus (AS); and a visual stimulus accompanied by a startle auditory stimulus (SS). Peak RFD, peak velocity, onset movement, movement duration and electromyography from pectoralis and tricep muscles were recorded. The SS condition induced an increase in the RFD and peak velocity and a reduction in the movement onset and duration, in comparison with the VS and AS condition. The onset activation of the pectoralis and tricep muscles was shorter for the SS than for the VS and AS conditions. These findings point out to specific enhancement effects of loud auditory stimulation on the rate of force development. This is of relevance since startle stimuli could be used to explore neural adaptations to resistance training. PMID:24489967

  13. [Macroeconomic analysis: agro-nutritional dynamics].

    PubMed

    Coussy, J

    1992-01-01

    This reflection on the renewed prominence of macroeconomic analysis in the area of food and agriculture, especially in Africa, assesses the history, limitations, and potential of the discipline as applied in formulation of agricultural policy. It begins by tracing the development and history of macroeconomic analysis from the emergence of liberal political economy in the late 18th century. The evolution of macroeconomic analysis applied to food and agriculture has not been linear; periods of eclipse have alternated with periods of influence. Most recently, in the 1960s, macroeconomic analysis was important in attempts to understand the place of agriculture in national economies, but the misuse of its vocabulary to justify a number of controversial policy actions created lasting distrust. The questions addressed by macroeconomic analysis and the potential contributions of its use in the 1960s are discussed, followed by an analysis of the reasons for renewed attention to the macroeconomic viewpoint beginning with the balance of payments crisis of the 1980s. The recent growth of institutional demand for macroeconomic analysis and policy has been accompanied by misunderstanding and inflated expectations as to its usefulness, while suspicions linger. The pressures encouraging broadened use of macroeconomic analysis are identified, including the growing influence of purely macroeconomic processes such as urbanization, the demographic transition, and the debt crisis; the intensifying of national and international market constraints affecting food and agriculture; and the legitimation of macroeconomic terminology by the large international organizations. Misapplications of macroeconomic analysis are identified, such as an erroneous equating of "macroeconomy" with "global economy". The lack of consensus among macroeconomic theorists about policies ostensibly based on macroeconomic analysis is discussed, as is the sometimes strained relationship between them and specialists

  14. Performance and Flow Dynamics Studies of Polymeric Optofluidic SERS Sensors

    NASA Astrophysics Data System (ADS)

    Uusitalo, S.; Hiltunen, J.; Karioja, P.; Siitonen, S.; Kontturi, V.; Myllylä, R.; Kinnunen, M.; Meglinski, I.

    2015-09-01

    We present a polymer-based optofluidic surface enhanced Raman scattering chip for biomolecule detection, serving as a disposable sensor choice with cost-effective production. The SERS substrate is fabricated by using industrial roll-to-roll UV-nanoimprinting equipment and integrated with adhesive-based polymeric microfluidics. The functioning of the SERS detection on-chip is confirmed and the effect of the polymer lid on the obtainable Raman spectra is analysed. Rhodamine 6G is used as a model analyte to demonstrate continuous flow measurements on a planar SERS substrate in a microchannel. The relation between the temporal response of the sensors and sample flow dynamics is studied with varied flow velocities, using SERS and fluorescence detection. The response time of the surface-dependent SERS signal is longer than the response time of the fluorescence signal of the bulk flow. This observation revealed the effect of convection on the temporal SERS responses at 25 μl/min to 1000 µl/min flow velocities. The diffusion of analyte molecules from the bulk concentration into the sensing surface induces about a 40-second lag time in the SERS detection. This lag time, and its rising trend with slower flow velocities, has to be taken into account in future trials of the optofluidic SERS sensor, with active analyte binding on the sensing surface.

  15. Personal and Network Dynamics in Performance of Knowledge Workers: A Study of Australian Breast Radiologists

    PubMed Central

    Tavakoli Taba, Seyedamir; Hossain, Liaquat; Heard, Robert; Brennan, Patrick; Lee, Warwick; Lewis, Sarah

    2016-01-01

    Materials and Methods In this paper, we propose a theoretical model based upon previous studies about personal and social network dynamics of job performance. We provide empirical support for this model using real-world data within the context of the Australian radiology profession. An examination of radiologists’ professional network topology through structural-positional and relational dimensions and radiologists’ personal characteristics in terms of knowledge, experience and self-esteem is provided. Thirty one breast imaging radiologists completed a purpose designed questionnaire regarding their network characteristics and personal attributes. These radiologists also independently read a test set of 60 mammographic cases: 20 cases with cancer and 40 normal cases. A Jackknife free response operating characteristic (JAFROC) method was used to measure the performance of the radiologists’ in detecting breast cancers. Results Correlational analyses showed that reader performance was positively correlated with the social network variables of degree centrality and effective size, but negatively correlated with constraint and hierarchy. For personal characteristics, the number of mammograms read per year and self-esteem (self-evaluation) positively correlated with reader performance. Hierarchical multiple regression analysis indicated that the combination of number of mammograms read per year and network’s effective size, hierarchy and tie strength was the best fitting model, explaining 63.4% of the variance in reader performance. The results from this study indicate the positive relationship between reading high volumes of cases by radiologists and expertise development, but also strongly emphasise the association between effective social/professional interactions and informal knowledge sharing with high performance. PMID:26918644

  16. Analysis of dynamic brain imaging data.

    PubMed Central

    Mitra, P P; Pesaran, B

    1999-01-01

    Modern imaging techniques for probing brain function, including functional magnetic resonance imaging, intrinsic and extrinsic contrast optical imaging, and magnetoencephalography, generate large data sets with complex content. In this paper we develop appropriate techniques for analysis and visualization of such imaging data to separate the signal from the noise and characterize the signal. The techniques developed fall into the general category of multivariate time series analysis, and in particular we extensively use the multitaper framework of spectral analysis. We develop specific protocols for the analysis of fMRI, optical imaging, and MEG data, and illustrate the techniques by applications to real data sets generated by these imaging modalities. In general, the analysis protocols involve two distinct stages: "noise" characterization and suppression, and "signal" characterization and visualization. An important general conclusion of our study is the utility of a frequency-based representation, with short, moving analysis windows to account for nonstationarity in the data. Of particular note are 1) the development of a decomposition technique (space-frequency singular value decomposition) that is shown to be a useful means of characterizing the image data, and 2) the development of an algorithm, based on multitaper methods, for the removal of approximately periodic physiological artifacts arising from cardiac and respiratory sources. PMID:9929474

  17. Dynamic pressure as a measure of gas turbine engine (GTE) performance

    NASA Astrophysics Data System (ADS)

    Rinaldi, G.; Stiharu, I.; Packirisamy, M.; Nerguizian, V.; Landry, R., Jr.; Raskin, J.-P.

    2010-04-01

    Utilizing in situ dynamic pressure measurement is a promising novel approach with applications for both control and condition monitoring of gas turbine-based propulsion systems. The dynamic pressure created by rotating components within the engine presents a unique opportunity for controlling the operation of the engine and for evaluating the condition of a specific component through interpretation of the dynamic pressure signal. Preliminary bench-top experiments are conducted with dc axial fans for measuring fan RPM, blade condition, surge and dynamic temperature variation. Also, a method, based on standing wave physics, is presented for measuring the dynamic temperature simultaneously with the dynamic pressure. These tests are implemented in order to demonstrate the versatility of dynamic pressure-based diagnostics for monitoring several different parameters, and two physical quantities, dynamic pressure and dynamic temperature, with a single sensor. In this work, the development of a dynamic pressure sensor based on micro-electro-mechanical system technology for in situ gas turbine engine condition monitoring is presented. The dynamic pressure sensor performance is evaluated on two different gas turbine engines, one having a fan and the other without.

  18. Principal component analysis of indocyanine green fluorescence dynamics for diagnosis of vascular diseases

    NASA Astrophysics Data System (ADS)

    Seo, Jihye; An, Yuri; Lee, Jungsul; Choi, Chulhee

    2015-03-01

    Indocyanine green (ICG), a near-infrared fluorophore, has been used in visualization of vascular structure and non-invasive diagnosis of vascular disease. Although many imaging techniques have been developed, there are still limitations in diagnosis of vascular diseases. We have recently developed a minimally invasive diagnostics system based on ICG fluorescence imaging for sensitive detection of vascular insufficiency. In this study, we used principal component analysis (PCA) to examine ICG spatiotemporal profile and to obtain pathophysiological information from ICG dynamics. Here we demonstrated that principal components of ICG dynamics in both feet showed significant differences between normal control and diabetic patients with vascula complications. We extracted the PCA time courses of the first three components and found distinct pattern in diabetic patient. We propose that PCA of ICG dynamics reveal better classification performance compared to fluorescence intensity analysis. We anticipate that specific feature of spatiotemporal ICG dynamics can be useful in diagnosis of various vascular diseases.

  19. Dynamic response analysis of a heavy commercial vehicle subjected to extreme road operating conditions

    NASA Astrophysics Data System (ADS)

    Chinnaraj, K.; Mangalaramanan, S. P.; Lakshmana Rao, C.

    2009-08-01

    Wheel excitations measured on a heavy commercial vehicle by driving it through extreme road operating conditions, are considered as inputs to perform dynamic response analysis in a simulated laboratory and computational environment. From initial modal analysis results using finite elements, critical vehicle frame rail locations are identified for dynamic laboratory strain measurements on a six poster road load simulator that employs dynamic wheel excitations as input. Dynamic stresses calculated from measured strain values are then compared with computationally obtained stress results on each of these locations. This study also points out all geometric locations and vibration modes that may affect the design behavior of the frame members under extreme road operating conditions. The results obtained from this work can be considered for further fatigue life prediction and design optimization of chassis frame rail assembly.

  20. Dynamic analysis of space structures including elastic, multibody, and control behavior

    NASA Technical Reports Server (NTRS)

    Pinson, Larry; Soosaar, Keto

    1989-01-01

    The problem is to develop analysis methods, modeling stategies, and simulation tools to predict with assurance the on-orbit performance and integrity of large complex space structures that cannot be verified on the ground. The problem must incorporate large reliable structural models, multi-body flexible dynamics, multi-tier controller interaction, environmental models including 1g and atmosphere, various on-board disturbances, and linkage to mission-level performance codes. All areas are in serious need of work, but the weakest link is multi-body flexible dynamics.

  1. Gravity-gradient dynamics experiments performed in orbit utilizing the Radio Astronomy Explorer (RAE-1) spacecraft

    NASA Technical Reports Server (NTRS)

    Walden, H.

    1973-01-01

    Six dynamic experiments were performed in earth orbit utilizing the RAE spacecraft in order to test the accuracy of the mathematical model of RAE dynamics. The spacecraft consisted of four flexible antenna booms, mounted on a rigid cylindrical spacecraft hub at center, for measuring radio emissions from extraterrestrial sources. Attitude control of the gravity stabilized spacecraft was tested by using damper clamping, single lower leading boom operations, and double lower boom operations. Results and conclusions of the in-orbit dynamic experiments proved the accuracy of the analytic techniques used to model RAE dynamical behavior.

  2. General Dynamic (GD) Launch Waveform On-Orbit Performance Report

    NASA Technical Reports Server (NTRS)

    Briones, Janette C.; Shalkhauser, Mary Jo

    2014-01-01

    The purpose of this report is to present the results from the GD SDR on-orbit performance testing using the launch waveform over TDRSS. The tests include the evaluation of well-tested waveform modes, the operation of RF links that are expected to have high margins, the verification of forward return link operation (including full duplex), the verification of non-coherent operational models, and the verification of radio at-launch operational frequencies. This report also outlines the launch waveform tests conducted and comparisons to the results obtained from ground testing.

  3. Auditory virtual environment with dynamic room characteristics for music performances

    NASA Astrophysics Data System (ADS)

    Choi, Daniel Dhaham

    A room-adaptive system was designed to simulate an electro-acoustic space that changes room characteristics in real-time according to the content of sound. In this specific case, the focus of the sound components is on the different styles and genres of music. This system is composed of real-time music recognition algorithms that analyze the different elements of music, determine the desired room characteristics, and output the acoustical parameters via multi-channel room simulation mechanisms. The system modifies the acoustic properties of a space and enables it to "improvise" its acoustical parameters based on the sounds of the music performances.

  4. Crustal Dynamics Project data analysis, 1990

    NASA Technical Reports Server (NTRS)

    Caprette, D. S.; Ma, C.; Ryan, J. W.

    1990-01-01

    The Goddard Very Long Baseline Interferometry (VLBI) group reports the results of analyzing 1073 Mark 3 data sets acquired from fixed and mobile observing sites through the end of 1989 and available to the Crustal Dynamics Project. Two large solutions, GLB656 and GLB657, were used to establish a VLBI reference frame with an origin coincident with the ITRF89. Another large solution, GLB658, was used to obtain Earth rotation parameters, nutation offsets, and global source positions. Site velocities were obtained from another large solution, GLB659. A fifth large solution, GLB660, was used to obtain baseline evolution. Site positions are tabulated on a yearly basis from 1979 through 1992. Site velocities are presented in both Cartesian and topocentric coordinates. The results include 76 sources, 80 sites, and 422 baselines.

  5. Dynamic mechanical analysis of fiber reinforced composites

    NASA Technical Reports Server (NTRS)

    Reed, K. E.

    1979-01-01

    Dynamic mechanical and thermal properties were determined for unidirectional epoxy/glass composites at various fiber orientation angles. Resonant frequency and relative logarithmic decrement were measured as functions of temperature. In low angle and longitudinal specimens a transition was observed above the resin glass transition temperature which was manifested mechanically as an additional damping peak and thermally as a change in the coefficient of thermal expansion. The new transition was attributed to a heterogeneous resin matrix induced by the fiber. The temperature span of the glass-rubber relaxation was found to broaden with decreasing orientation angle, reflecting the growth of fiber contribution and exhibiting behavior similar to that of Young's modulus. The change in resonant frequency through the glass transition was greatest for samples of intermediate fiber angle, demonstrating behavior similar to that of the longitudinal shear modulus.

  6. Dynamic headspace analysis of fresh tomato juices.

    PubMed

    Sucan, M K; Russell, G F

    2001-01-01

    The methods used to isolate volatile compounds for GC analyses can cause profound effects on the quantitative and qualitative composition of the injected sample, and exert a great influence in the resultant bioactivity of volatiles. Especially with plant tissues like tomatoes, the isolation of volatile constituents using classical methods may yield results which are not representative of the chemicals present in the natural material. Headspace sampling methods may be advantageous in capturing the same volatile compounds emitted from tomatoes that are detected by the human nose. This study utilized an extremely sensitive dynamic headspace sampling with thermal desorption method to determine volatile components of fresh tomato juices. The method proved very sensitive for the isolation of tomato volatiles and concentrations of flavor compounds were much greater than related literature studies.

  7. Ion mobility analysis of molecular dynamics.

    PubMed

    Wyttenbach, Thomas; Pierson, Nicholas A; Clemmer, David E; Bowers, Michael T

    2014-01-01

    The combination of mass spectrometry and ion mobility spectrometry (IMS) employing a temperature-variable drift cell or a drift tube divided into sections to make IMS-IMS experiments possible allows information to be obtained about the molecular dynamics of polyatomic ions in the absence of a solvent. The experiments allow the investigation of structural changes of both activated and native ion populations on a timescale of 1-100 ms. Five different systems representing small and large, polar and nonpolar molecules, as well as noncovalent assemblies, are discussed in detail: a dinucleotide, a sodiated polyethylene glycol chain, the peptide bradykinin, the protein ubiquitin, and two types of peptide oligomers. Barriers to conformational interconversion can be obtained in favorable cases. In other cases, solution-like native structures can be observed, but care must be taken in the experimental protocols. The power of theoretical modeling is demonstrated.

  8. Nonlinear dynamic analysis of flexible multibody systems

    NASA Technical Reports Server (NTRS)

    Bauchau, Olivier A.; Kang, Nam Kook

    1991-01-01

    Two approaches are developed to analyze the dynamic behavior of flexible multibody systems. In the first approach each body is modeled with a modal methodology in a local non-inertial frame of reference, whereas in the second approach, each body is modeled with a finite element methodology in the inertial frame. In both cases, the interaction among the various elastic bodies is represented by constraint equations. The two approaches were compared for accuracy and efficiency: the first approach is preferable when the nonlinearities are not too strong but it becomes cumbersome and expensive to use when many modes must be used. The second approach is more general and easier to implement but could result in high computation costs for a large system. The constraints should be enforced in a time derivative fashion for better accuracy and stability.

  9. Dynamic asset trees and portfolio analysis

    NASA Astrophysics Data System (ADS)

    Onnela, J.-P.; Chakraborti, A.; Kaski, K.; Kertiész, J.

    2002-12-01

    The minimum spanning tree, based on the concept of ultrametricity, is constructed from the correlation matrix of stock returns and provides a meaningful economic taxonomy of the stock market. In order to study the dynamics of this asset tree we characterise it by its normalised length and by the mean occupation layer, as measured from an appropriately chosen centre called the `central node'. We show how the tree evolves over time, and how it shrinks strongly, in particular, during a stock market crisis. We then demonstrate that the assets of the optimal Markowitz portfolio lie practically at all times on the outskirts of the tree. We also show that the normalised tree length and the investment diversification potential are very strongly correlated.

  10. Wheat yield dynamics: a structural econometric analysis.

    PubMed

    Sahin, Afsin; Akdi, Yilmaz; Arslan, Fahrettin

    2007-10-15

    In this study we initially have tried to explore the wheat situation in Turkey, which has a small-open economy and in the member countries of European Union (EU). We have observed that increasing the wheat yield is fundamental to obtain comparative advantage among countries by depressing domestic prices. Also the changing structure of supporting schemes in Turkey makes it necessary to increase its wheat yield level. For this purpose, we have used available data to determine the dynamics of wheat yield by Ordinary Least Square Regression methods. In order to find out whether there is a linear relationship among these series we have checked each series whether they are integrated at the same order or not. Consequently, we have pointed out that fertilizer usage and precipitation level are substantial inputs for producing high wheat yield. Furthermore, in respect for our model, fertilizer usage affects wheat yield more than precipitation level.

  11. Dynamics of hydrogenated amorphous silicon flexural resonators for enhanced performance

    NASA Astrophysics Data System (ADS)

    Mouro, J.; Chu, V.; Conde, J. P.

    2016-04-01

    Hydrogenated amorphous silicon thin-film flexural resonators with sub-micron actuation gaps are fabricated by surface micromachining on glass substrates. Experimentally, the resonators are electrostatically actuated and their motion is optically detected. Three different configurations for the electrostatic excitation force are used to study the dynamics of the resonators. In the first case, a dc voltage (Vdc) is added to an ac voltage with variable excitation frequency (Vac(ω)) and harmonic, superharmonic, and subharmonic resonances of different orders are observed. The second case consists on mixing the dc voltage (Vdc) with an ac voltage applied at a fixed frequency of twice the natural frequency of the resonator (V(2ω0)). High-amplitude parametric resonance is excited at the natural frequency of the system, ω0. This configuration allows a separation between the frequencies of the excitation and the mechanical motion. Finally, in the third case, the dc voltage (Vdc) is combined with both ac voltages, Vac(ω) and V(2ω0), and parametric resonance is excited and emerges from the fundamental harmonic resonance peak. The single-degree-of-freedom equation of motion is modeled and discussed for each case. The nonlinearity inherent to the electrostatic force is responsible for modulating the spring constant of the system at different frequencies, giving rise to parametric resonance. These equations of motion are simulated in the time and frequency domains, providing a consistent explanation of the experimentally observed phenomena. A wide variety of possible resonance modes with different characteristics can be used advantageously in MEMS device design.

  12. Ongoing Analyses 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 H.; Holt, James B.; Canabal, Francisco

    2001-01-01

    This paper presents the status of analyses on three Rocket Based Combined Cycle (RBCC) configurations underway in the Applied Fluid Dynamics Analysis Group (TD64). TD64 is performing computational fluid dynamics (CFD) 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 (FDNS) code for ejector mode fluid dynamics. The Draco analysis was 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.

  13. Automatic Human Movement Assessment with Switching Linear Dynamic System: Motion Segmentation and Motor Performance.

    PubMed

    de Souza Baptista, Roberto; Bo, Antonio; Hayashibe, Mitsuhiro

    2016-07-14

    Performance assessment of human movement is critical in diagnosis and motor-control rehabilitation. Recent developments in portable sensor technology enable clinicians to measure spatiotemporal aspects to aid in the neurological assessment. However the extraction of quantitative information from such measurements is usually done manually through visual inspection. This paper presents a novel framework for automatic human movement assessment that executes segmentation and motor performance parameter extraction in time-series of measurements from a sequence of human movements. We use the elements of a Switching Linear Dynamic System model as building blocks to translate formal definitions and procedures from human movement analysis. Our approach provides a method for users with no expertise in signal processing to create models for movements using labeled dataset and latter use it for automatic assessment. We validated our framework on preliminary tests involving six healthy adult subjects that executed common movements in functional tests and rehabilitation exercise sessions, such as sit-to-stand and lateral elevation of the arms and five elderly subjects, two of which with limited mobility, that executed the sit-to-stand movement. The proposed method worked on random motion sequences for the dual purpose of movement segmentation (accuracy of 72-100%) and motor performance assessment (mean error of 0-12%).

  14. Dynamic fracture mechanics analysis for an edge delamination crack

    NASA Technical Reports Server (NTRS)

    Rizzi, Stephen A.; Doyle, James F.

    1994-01-01

    A global/local analysis is applied to the problem of a panel with an edge delamination crack subject to an impulse loading to ascertain the dynamic J integral. The approach uses the spectral element method to obtain the global dynamic response and local resultants to obtain the J integral. The variation of J integral along the crack front is shown. The crack behavior is mixed mode (Mode 2 and Mode 3), but is dominated by the Mode 2 behavior.

  15. Motif-Synchronization: A new method for analysis of dynamic brain networks with EEG

    NASA Astrophysics Data System (ADS)

    Rosário, R. S.; Cardoso, P. T.; Muñoz, M. A.; Montoya, P.; Miranda, J. G. V.

    2015-12-01

    The major aim of this work was to propose a new association method known as Motif-Synchronization. This method was developed to provide information about the synchronization degree and direction between two nodes of a network by counting the number of occurrences of some patterns between any two time series. The second objective of this work was to present a new methodology for the analysis of dynamic brain networks, by combining the Time-Varying Graph (TVG) method with a directional association method. We further applied the new algorithms to a set of human electroencephalogram (EEG) signals to perform a dynamic analysis of the brain functional networks (BFN).

  16. Dynamic analysis of a closed-cycle solar adsorption refrigerator using two adsorbent-adsorbate pairs

    SciTech Connect

    Hajji, A. ); Worek, W. ); Lavan, Z. )

    1991-05-01

    In this paper a dynamic analysis of a closed-cycle, solar adsorption refrigerator is presented. The instantaneous and daily system performance are studied using two adsorbent-adsorbate pairs, Zeolite 13X-Water and Chabazite-Methanol. The effect of design and operating parameters, including inert material thermal capacitance, matrix porosity, and evaporation and condenser temperatures on the solar and cycle coefficients of performance are evaluated.

  17. Movement Characteristics Analysis and Dynamic Simulation of Collaborative Measuring Robot

    NASA Astrophysics Data System (ADS)

    guoqing, MA; li, LIU; zhenglin, YU; guohua, CAO; yanbin, ZHENG

    2017-03-01

    Human-machine collaboration is becoming increasingly more necessary, and so collaborative robot applications are also in high demand. We selected a UR10 robot as our research subject for this study. First, we applied D-H coordinate transformation of the robot to establish a link system, and we then used inverse transformation to solve the robot’s inverse kinematics and find all the joints. Use Lagrange method to analysis UR robot dynamics; use ADAMS multibody dynamics simulation software to dynamic simulation; verifying the correctness of the derived kinetic models.

  18. An Ethnostatistical Analysis of Performance Measurement

    ERIC Educational Resources Information Center

    Winiecki, Donald J.

    2008-01-01

    Within the fields of human performance technology (HPT), human resources management (HRM), and management in general, performance measurement is not only foundational but considered necessary at all phases in the process of HPT. In HPT in particular, there is substantial advice literature on what measurement is, why it is essential, and (at a…

  19. Blade loss transient dynamic analysis of turbomachinery

    NASA Technical Reports Server (NTRS)

    Stallone, M. J.; Gallardo, V.; Storace, A. F.; Bach, L. J.; Black, G.; Gaffney, E. F.

    1982-01-01

    This paper reports on work completed to develop an analytical method for predicting the transient non-linear response of a complete aircraft engine system due to the loss of a fan blade, and to validate the analysis by comparing the results against actual blade loss test data. The solution, which is based on the component element method, accounts for rotor-to-casing rubs, high damping and rapid deceleration rates associated with the blade loss event. A comparison of test results and predicted response show good agreement except for an initial overshoot spike not observed in test. The method is effective for analysis of large systems.

  20. EPID-based verification of the MLC performance for dynamic IMRT and VMAT

    SciTech Connect

    Rowshanfarzad, Pejman; Sabet, Mahsheed; Barnes, Michael P.; O'Connor, Daryl J.; Greer, Peter B.

    2012-10-15

    Purpose: In advanced radiotherapy treatments such as intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), verification of the performance of the multileaf collimator (MLC) is an essential part of the linac QA program. The purpose of this study is to use the existing measurement methods for geometric QA of the MLCs and extend them to more comprehensive evaluation techniques, and to develop dedicated robust algorithms to quantitatively investigate the MLC performance in a fast, accurate, and efficient manner. Methods: The behavior of leaves was investigated in the step-and-shoot mode by the analysis of integrated electronic portal imaging device (EPID) images acquired during picket fence tests at fixed gantry angles and arc delivery. The MLC was also studied in dynamic mode by the analysis of cine EPID images of a sliding gap pattern delivered in a variety of conditions including different leaf speeds, deliveries at fixed gantry angles or in arc mode, and changing the direction of leaf motion. The accuracy of the method was tested by detection of the intentionally inserted errors in the delivery patterns. Results: The algorithm developed for the picket fence analysis was able to find each individual leaf position, gap width, and leaf bank skewness in addition to the deviations from expected leaf positions with respect to the beam central axis with sub-pixel accuracy. For the three tested linacs over a period of 5 months, the maximum change in the gap width was 0.5 mm, the maximum deviation from the expected leaf positions was 0.1 mm and the MLC skewness was up to 0.2 Degree-Sign . The algorithm developed for the sliding gap analysis could determine the velocity and acceleration/deceleration of each individual leaf as well as the gap width. There was a slight decrease in the accuracy of leaf performance with increasing leaf speeds. The analysis results were presented through several graphs. The accuracy of the method was assessed

  1. Performance and Degradation Analysis of Operating PV Systems

    NASA Astrophysics Data System (ADS)

    Da Silva Freire, Felipe

    The environmental concerns together with the decrease in technology cost lead the solar market to growth rapidly along the last decade. The photovoltaic (PV) systems are one of the solar energy alternatives and the silicon solar cells are currently the most widespread technology. Photovoltaic (PV) modules are considered the most reliable component of a photovoltaic system. The reliability and lifetime depends on the modules energy conversion performance and degradation modes. The analysis of monitoring data give insights about the PV system performance along its service time. The comparison between this data and mathematical models configure a way to predict the futures and new PV installations performance. The goal of this study is to understand the PV systems performance and degradation along its lifetime. A mathematical model was employed to predict the power output of a real, relatively new operating PV system with respect to environmental parameters temperature, irradiance and cloud coverage. The model used is based on one diode ideality factor and takes into account the parasitic series resistance. The results have been compared with the actual PV output data collected for the year 2014 and show good correlation. As the model predicts the system power output assuming the system in new conditions, the deviation in performance of the real data in comparison to the modeling results need to be further investigated for systems in service for longer time. For this propose, the study presents a condensed review of various causes of degradation in silicon PV modules and techniques to observe and investigate these degradation mechanisms. Major effects on output performance exhibit increase in observed ideality factor n2 and recombination current J02 primarily caused by decrease in minority carrier lifetime, shunts and increase in series resistance. The study further, investigates the governing degradation modes on a ten years old PV crystalline silicon module

  2. Effects of visual flight display dynamics on altitude tracking performance in a flight simulator

    NASA Technical Reports Server (NTRS)

    Weener, E. F.; Howe, R. M.; Pew, R. W.

    1973-01-01

    The effects were studied of visual display dynamics on pilot tracking performance in a simulator. The tracking task consisted of maintaining the piloted aircraft at the same altitude as two aircraft positioned three-hundred feet ahead; as would be required in level formation flying. The two leading aircraft were represented symbolically along with the horizon on a CRT display. Vertical position of these aircraft with respect to the horizon indicated the altitude of the subject's aircraft, which was disturbed by atmospheric turbulence. Various bandwidths of second-order dynamics were interposed between the true aircraft altitude and the displayed altitude, whereas no dynamics were interposed in the attitude display. Experiments were run using two experienced pilots and two substantially different longitudinal dynamics for the piloted aircraft. Preliminary results indicate a significant decrease in altitude tracking performance for display dynamics with natural frequencies below ten radians per second.

  3. Spacecraft Multiple Array Communication System Performance Analysis

    NASA Technical Reports Server (NTRS)

    Hwu, Shian U.; Desilva, Kanishka; Sham, Catherine C.

    2010-01-01

    The Communication Systems Simulation Laboratory (CSSL) at the NASA Johnson Space Center is tasked to perform spacecraft and ground network communication system simulations, design validation, and performance verification. The CSSL has developed simulation tools that model spacecraft communication systems and the space and ground environment in which the tools operate. In this paper, a spacecraft communication system with multiple arrays is simulated. Multiple array combined technique is used to increase the radio frequency coverage and data rate performance. The technique is to achieve phase coherence among the phased arrays to combine the signals at the targeting receiver constructively. There are many technical challenges in spacecraft integration with a high transmit power communication system. The array combining technique can improve the communication system data rate and coverage performances without increasing the system transmit power requirements. Example simulation results indicate significant performance improvement can be achieved with phase coherence implementation.

  4. Dynamic performance of the beam position monitor support at the SSRF.

    PubMed

    Wang, Xiao; Cao, Yun; Du, Hanwen; Yin, Lixin

    2009-01-01

    Electron beam stability is very important for third-generation light sources, especially for the Shanghai Synchrotron Radiation Facility whose ground vibrations are much larger than those for other light sources. Beam position monitors (BPMs), used to monitor the position of the electron beam, require a greater stability than other mechanical structures. This paper concentrates on an investigation of the dynamic performance of the BPM support prototype. Modal and response analyses have been carried out by finite-element (FE) calculations and vibration measurements. Inconsistent results between calculation and measurement have motivated a change in the soft connections between the support and the ground from a ground bolt in the initial design to full grout. As a result the mechanical stability of the BPM support is greatly improved, showing an increase in the first eigenfrequency from 20.2 Hz to 50.2 Hz and a decrease in the ratio of the root-mean-square displacement (4-50 Hz) between the ground and the top of the support from 4.36 to 1.23 in the lateral direction. An example is given to show how FE analysis can guide the mechanical design and dynamic measurements (i.e. it is not just used as a verification method). Similar ideas can be applied to improve the stability of other mechanical structures.

  5. Performance analysis of a digital capacitance measuring circuit

    NASA Astrophysics Data System (ADS)

    Xu, Lijun; Sun, Shijie; Cao, Zhang; Yang, Wuqiang

    2015-05-01

    This paper presents the design and study of a digital capacitance measuring circuit with theoretical analysis, numerical simulation, and experimental evaluation. The static and dynamic performances of the capacitance measuring circuit are first defined, including signal-to-noise ratio (SNR), standard deviation, accuracy, linearity, sensitivity, and response time, within a given measurement range. Then numerical simulation is carried out to analyze the SNR and standard deviation of the circuit, followed by experiments to validate the overall performance of the circuit. The simulation results show that when the standard deviation of noise is 0.08 mV and the measured capacitance decreases from 6 pF to 3 fF, the SNR decreases from 90 dB to 22 dB and the standard deviation is between 0.17 fF and 0.24 fF. The experimental results show that when the measured capacitance decreases from 6 pF to 40 fF and the data sampled in a single period are used for demodulation, the SNR decreases from 88 dB to 40 dB and the standard deviation is between 0.18 fF and 0.25 fF. The maximum absolute error and relative error are 5.12 fF and 1.26%, respectively. The SNR and standard deviation can be further improved if the data sampled in more than one period are used for demodulation by the circuit.

  6. Design and Performance of Overlap FFT Filter-Bank for Dynamic Spectrum Access Applications

    NASA Astrophysics Data System (ADS)

    Tanabe, Motohiro; Umehira, Masahiro

    An OFDMA-based (Orthogonal Frequency Division Multiple Access-based) channel access scheme for dynamic spectrum access has the drawbacks of large PAPR (Peak to Average Power Ratio) and large ACI (Adjacent Channel Interference). To solve these problems, a flexible channel access scheme using an overlap FFT filter-bank was proposed based on single carrier modulation for dynamic spectrum access. In order to apply the overlap FFT filter-bank for dynamic spectrum access, it is necessary to clarify the performance of the overlap FFT filter-bank according to the design parameters since its frequency characteristics are critical for dynamic spectrum access applications. This paper analyzes the overlap FFT filter-bank and evaluates its performance such as frequency characteristics and ACI performance according to the design parameters.

  7. Dynamic mechanical analysis of supercooled water in nanoporous confinement

    NASA Astrophysics Data System (ADS)

    Soprunyuk, Viktor; Schranz, Wilfried; Huber, Patrick

    2016-08-01

    Dynamical mechanical analysis (\\text{DMA})(f=0.2\\text{--}100 \\text{Hz}) is used to study the dynamics of confined water in mesoporous Gelsil (2.6 nm and 5 nm pores) and Vycor (10 nm) in the temperature range from T=80 \\text{K} to 300 K. Confining water into nanopores partly suppresses crystallization and allows us to perform measurements of supercooled water below 235 K, i.e., in water's so-called “no man's land”, in parts of the pores. Two distinct relaxation peaks are observed in tan δ around T1 ≈ 145 \\text{K} (P1) and T2 ≈ 205 \\text{K}~(P2) for Gelsil 2.6 nm and Gelsil 5 nm at 0.2 Hz. Both peaks shift to higher T with increasing pore size d and change with f in a systematic way, typical of an Arrhenius behaviour of the corresponding relaxation times. For P 1 we obtain an average activation energy of E\\text{a} = 0.47 \\text{eV} , in good agreement with literature values, suggesting that P 1 corresponds to the glass transition of supercooled water. The observation of a pronounced softening of the Young's modulus around 165 K (for Gelsil 2.6 nm at 0.2 Hz) supports the conjecture of a glass-to-liquid transition in the vicinity of P 1. In addition we find a clear-cut (1/d)-dependence of the calculated glass transition temperatures which extrapolates to T_\\text{g}(1/d=0)=136 \\text{K} , in agreement with the traditional value of water.

  8. Toward Capturing Momentary Changes of Heart Rate Variability by a Dynamic Analysis Method

    PubMed Central

    Zhang, Haoshi; Zhu, Mingxing; Zheng, Yue; Li, Guanglin

    2015-01-01

    The analysis of heart rate variability (HRV) has been performed on long-term electrocardiography (ECG) recordings (12~24 hours) and short-term recordings (2~5 minutes), which may not capture momentary change of HRV. In this study, we present a new method to analyze the momentary HRV (mHRV). The ECG recordings were segmented into a series of overlapped HRV analysis windows with a window length of 5 minutes and different time increments. The performance of the proposed method in delineating the dynamics of momentary HRV measurement was evaluated with four commonly used time courses of HRV measures on both synthetic time series and real ECG recordings from human subjects and dogs. Our results showed that a smaller time increment could capture more dynamical information on transient changes. Considering a too short increment such as 10 s would cause the indented time courses of the four measures, a 1-min time increment (4-min overlapping) was suggested in the analysis of mHRV in the study. ECG recordings from human subjects and dogs were used to further assess the effectiveness of the proposed method. The pilot study demonstrated that the proposed analysis of mHRV could provide more accurate assessment of the dynamical changes in cardiac activity than the conventional measures of HRV (without time overlapping). The proposed method may provide an efficient means in delineating the dynamics of momentary HRV and it would be worthy performing more investigations. PMID:26172953

  9. Acute effects of dynamic stretching, static stretching, and light aerobic activity on muscular performance in women.

    PubMed

    Curry, Brad S; Chengkalath, Devendra; Crouch, Gordon J; Romance, Michelle; Manns, Patricia J

    2009-09-01

    The purpose of this study was to compare three warm-up protocols--static stretching, dynamic stretching, and light aerobic activity--on selected measures of range of motion and power in untrained females and to investigate the sustained effects at 5 and 30 minutes after warm-up. A total of 24 healthy females (ages 23-29 years) attended one familiarization session and three test sessions on nonconsecutive days within 2 weeks. A within-subject design protocol with the testing investigators blinded to the subjects' warm-up was followed. Each session started with 5 minutes of light aerobic cycling followed by pretest baseline measures. Another 5 minutes of light aerobic cycling was completed and followed by one of the three randomly selected warm-up interventions (static stretching, dynamic stretching, or light aerobic activity). The following posttest outcome measures were collected 5 and 30 minutes following the intervention: modified Thomas test, countermovement jump, and isometric time to peak force knee extension measured by dynamometer. Analysis of the data revealed significant time effects on range of motion and countermovement jump changes. No significant differences (p > 0.05) were found between the warm-up conditions on any of the variables. The variation in responses to warm-up conditions emphasizes the unique nature of individual reactions to different warm-ups; however, there was a tendency for warm-ups with an active component to have beneficial effects. The data suggests dynamic stretching has greater applicability to enhance performance on power outcomes compared to static stretching.

  10. Rocketdyne automated dynamics data analysis and management system

    NASA Technical Reports Server (NTRS)

    Tarn, Robert B.

    1988-01-01

    An automated dynamics data analysis and management systems implemented on a DEC VAX minicomputer cluster is described. Multichannel acquisition, Fast Fourier Transformation analysis, and an online database have significantly improved the analysis of wideband transducer responses from Space Shuttle Main Engine testing. Leakage error correction to recover sinusoid amplitudes and correct for frequency slewing is described. The phase errors caused by FM recorder/playback head misalignment are automatically measured and used to correct the data. Data compression methods are described and compared. The system hardware is described. Applications using the data base are introduced, including software for power spectral density, instantaneous time history, amplitude histogram, fatigue analysis, and rotordynamics expert system analysis.

  11. Improving transient performance of adaptive control architectures using frequency-limited system error dynamics

    NASA Astrophysics Data System (ADS)

    Yucelen, Tansel; De La Torre, Gerardo; Johnson, Eric N.

    2014-11-01

    Although adaptive control theory offers mathematical tools to achieve system performance without excessive reliance on dynamical system models, its applications to safety-critical systems can be limited due to poor transient performance and robustness. In this paper, we develop an adaptive control architecture to achieve stabilisation and command following of uncertain dynamical systems with improved transient performance. Our framework consists of a new reference system and an adaptive controller. The proposed reference system captures a desired closed-loop dynamical system behaviour modified by a mismatch term representing the high-frequency content between the uncertain dynamical system and this reference system, i.e., the system error. In particular, this mismatch term allows the frequency content of the system error dynamics to be limited, which is used to drive the adaptive controller. It is shown that this key feature of our framework yields fast adaptation without incurring high-frequency oscillations in the transient performance. We further show the effects of design parameters on the system performance, analyse closeness of the uncertain dynamical system to the unmodified (ideal) reference system, discuss robustness of the proposed approach with respect to time-varying uncertainties and disturbances, and make connections to gradient minimisation and classical control theory. A numerical example is provided to demonstrate the efficacy of the proposed architecture.

  12. Path analysis of self-efficacy and diving performance revisited.

    PubMed

    Feltz, Deborah L; Chow, Graig M; Hepler, Teri J

    2008-06-01

    The Feltz (1982) path analysis of the relationship between diving efficacy and performance showed that, over trials, past performance was a stronger predictor than self-efficacy of performance. Bandura (1997) criticized the study as statistically "overcontrolling" for past performance by using raw past performance scores along with self-efficacy as predictors of performance. He suggests residualizing past performance by regressing the raw scores on self-efficacy and entering them into the model to remove prior contributions of self-efficacy imbedded in past performance scores. To resolve this controversy, we reanalyzed the Feltz data using three statistical models: raw past performance, residual past performance, and a method that residualizes past performance and self-efficacy. Results revealed that self-efficacy was a stronger predictor of performance in both residualized models than in the raw past performance model. Furthermore, the influence of past performance on future performance was weaker when the residualized methods were conducted.

  13. Assessing BMP Performance Using Microtox Toxicity Analysis

    EPA Science Inventory

    Best Management Practices (BMPs) have been shown to be effective in reducing runoff and pollutants from urban areas and thus provide a mechanism to improve downstream water quality. Currently, BMP performance regarding water quality improvement is assessed through measuring each...

  14. Space conditioning performance analysis and simulation study

    NASA Astrophysics Data System (ADS)

    Patani, A.; Bonne, U.

    1981-07-01

    The engine driven heat pump model was expanded to incorporate an approach for evaluating the influence of cycling and systems included the sensitivity of performance to electric consumption, compressor speed, mixing, and climate. A modular program for evaluating the steady state performance of absorption heat pumps was developed. Initial simulations indicated performance trends as a function of outdoor temperature and the refrigerant absorber charge. The combustion heating system model, HFLAME, was used to simulate the benefits of fan/pump overrun and the dependence of corresponding setpoints on off period losses and electric costs. Benefits of fuel, fuel/air modulation as compared to cyclic performance were also analyzed. An energy distribution factor was defined to describe the effect of the distribution system on realizing savings of retrofits.

  15. Conceptual design and analysis of a dynamic scale model of the Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Davis, D. A.; Gronet, M. J.; Tan, M. K.; Thorne, J.

    1994-01-01

    This report documents the conceptual design study performed to evaluate design options for a subscale dynamic test model which could be used to investigate the expected on-orbit structural dynamic characteristics of the Space Station Freedom early build configurations. The baseline option was a 'near-replica' model of the SSF SC-7 pre-integrated truss configuration. The approach used to develop conceptual design options involved three sets of studies: evaluation of the full-scale design and analysis databases, conducting scale factor trade studies, and performing design sensitivity studies. The scale factor trade study was conducted to develop a fundamental understanding of the key scaling parameters that drive design, performance and cost of a SSF dynamic scale model. Four scale model options were estimated: 1/4, 1/5, 1/7, and 1/10 scale. Prototype hardware was fabricated to assess producibility issues. Based on the results of the study, a 1/4-scale size is recommended based on the increased model fidelity associated with a larger scale factor. A design sensitivity study was performed to identify critical hardware component properties that drive dynamic performance. A total of 118 component properties were identified which require high-fidelity replication. Lower fidelity dynamic similarity scaling can be used for non-critical components.

  16. Dynamic Network-Based Epistasis Analysis: Boolean Examples

    PubMed Central

    Azpeitia, Eugenio; Benítez, Mariana; Padilla-Longoria, Pablo; Espinosa-Soto, Carlos; Alvarez-Buylla, Elena R.

    2011-01-01

    In this article we focus on how the hierarchical and single-path assumptions of epistasis analysis can bias the inference of gene regulatory networks. Here we emphasize the critical importance of dynamic analyses, and specifically illustrate the use of Boolean network models. Epistasis in a broad sense refers to gene interactions, however, as originally proposed by Bateson, epistasis is defined as the blocking of a particular allelic effect due to the effect of another allele at a different locus (herein, classical epistasis). Classical epistasis analysis has proven powerful and useful, allowing researchers to infer and assign directionality to gene interactions. As larger data sets are becoming available, the analysis of classical epistasis is being complemented with computer science tools and system biology approaches. We show that when the hierarchical and single-path assumptions are not met in classical epistasis analysis, the access to relevant information and the correct inference of gene interaction topologies is hindered, and it becomes necessary to consider the temporal dynamics of gene interactions. The use of dynamical networks can overcome these limitations. We particularly focus on the use of Boolean networks that, like classical epistasis analysis, relies on logical formalisms, and hence can complement classical epistasis analysis and relax its assumptions. We develop a couple of theoretical examples and analyze them from a dynamic Boolean network model perspective. Boolean networks could help to guide additional experiments and discern among alternative regulatory schemes that would be impossible or difficult to infer without the elimination of these assumption from the classical epistasis analysis. We also use examples from the literature to show how a Boolean network-based approach has resolved ambiguities and guided epistasis analysis. Our article complements previous accounts, not only by focusing on the implications of the hierarchical and

  17. Interactive Visual Analysis within Dynamic Ocean Models

    NASA Astrophysics Data System (ADS)

    Butkiewicz, T.

    2012-12-01

    The many observation and simulation based ocean models available today can provide crucial insights for all fields of marine research and can serve as valuable references when planning data collection missions. However, the increasing size and complexity of these models makes leveraging their contents difficult for end users. Through a combination of data visualization techniques, interactive analysis tools, and new hardware technologies, the data within these models can be made more accessible to domain scientists. We present an interactive system that supports exploratory visual analysis within large-scale ocean flow models. The currents and eddies within the models are illustrated using effective, particle-based flow visualization techniques. Stereoscopic displays and rendering methods are employed to ensure that the user can correctly perceive the complex 3D structures of depth-dependent flow patterns. Interactive analysis tools are provided which allow the user to experiment through the introduction of their customizable virtual dye particles into the models to explore regions of interest. A multi-touch interface provides natural, efficient interaction, with custom multi-touch gestures simplifying the otherwise challenging tasks of navigating and positioning tools within a 3D environment. We demonstrate the potential applications of our visual analysis environment with two examples of real-world significance: Firstly, an example of using customized particles with physics-based behaviors to simulate pollutant release scenarios, including predicting the oil plume path for the 2010 Deepwater Horizon oil spill disaster. Secondly, an interactive tool for plotting and revising proposed autonomous underwater vehicle mission pathlines with respect to the surrounding flow patterns predicted by the model; as these survey vessels have extremely limited energy budgets, designing more efficient paths allows for greater survey areas.

  18. Rocket-in-a-Duct Performance Analysis

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Reed, Brian D.

    1999-01-01

    An axisymmetric, 110 N class, rocket configured with a free expansion between the rocket nozzle and a surrounding duct was tested in an altitude simulation facility. The propellants were gaseous hydrogen and gaseous oxygen and the hardware consisted of a heat sink type copper rocket firing through copper ducts of various diameters and lengths. A secondary flow of nitrogen was introduced at the blind end of the duct to mix with the primary rocket mass flow in the duct. This flow was in the range of 0 to 10% of the primary massflow and its effect on nozzle performance was measured. The random measurement errors on thrust and massflow were within +/-1%. One dimensional equilibrium calculations were used to establish the possible theoretical performance of these rocket-in-a-duct nozzles. Although the scale of these tests was small, they simulated the relevant flow expansion physics at a modest experimental cost. Test results indicated that lower performance was obtained at higher free expansion area ratios and longer ducts, while, higher performance was obtained with the addition of secondary flow. There was a discernable peak in specific impulse efficiency at 4% secondary flow. The small scale of these tests resulted in low performance efficiencies, but prior numerical modeling of larger rocket-in-a-duct engines predicted performance that was comparable to that of optimized rocket nozzles. This remains to be proven in large-scale, rocket-in-a-duct tests.

  19. More than just the mean: moving to a dynamic view of performance-based compensation.

    PubMed

    Barnes, Christopher M; Reb, Jochen; Ang, Dionysius

    2012-05-01

    Compensation decisions have important consequences for employees and organizations and affect factors such as retention, motivation, and recruitment. Past research has primarily focused on mean performance as a predictor of compensation, promoting the implicit assumption that alternative aspects of dynamic performance are not relevant. To address this gap in the literature, we examined the influence of dynamic performance characteristics on compensation decisions in the National Basketball Association (NBA). We predicted that, in addition to performance mean, performance trend and variability would also affect compensation decisions. Results revealed that performance mean and trend, but not variability, were significantly and positively related to changes in compensation levels of NBA players. Moreover, trend (but not mean or variability) predicted compensation when controlling for future performance, suggesting that organizations overweighted trend in their compensation decisions. Theoretical and practical implications are discussed.

  20. Disassociation of static and dynamic cerebral autoregulatory performance in healthy volunteers after lipopolysaccharide infusion and in patients with sepsis.

    PubMed

    Berg, Ronan M G; Plovsing, Ronni R; Ronit, Andreas; Bailey, Damian M; Holstein-Rathlou, Niels-Henrik; Møller, Kirsten

    2012-12-01

    Sepsis is frequently complicated by brain dysfunction, which may be associated with disturbances in cerebral autoregulation, rendering the brain susceptible to hypoperfusion and hyperperfusion. The purpose of the present study was to assess static and dynamic cerebral autoregulation 1) in a human experimental model of the systemic inflammatory response during early sepsis and 2) in patients with advanced sepsis. Cerebral autoregulation was tested using transcranial Doppler ultrasound in healthy volunteers (n = 9) before and after LPS infusion and in patients with sepsis (n = 16). Static autoregulation was tested by norepinephrine infusion and dynamic autoregulation by transfer function analysis (TFA) of spontaneous oscillations between mean arterial blood pressure and middle cerebral artery blood flow velocity in the low frequency range (0.07-0.20 Hz). Static autoregulatory performance after LPS infusion and in patients with sepsis was similar to values in healthy volunteers at baseline. In contrast, TFA showed decreased gain and an increased phase difference between blood pressure and middle cerebral artery blood flow velocity after LPS (both P < 0.01 vs. baseline); patients exhibited similar gain but lower phase difference values (P < 0.01 vs. baseline and LPS), indicating a slower dynamic autoregulatory response. Our findings imply that static and dynamic cerebral autoregulatory performance may disassociate in sepsis; thus static autoregulation was maintained both after LPS and in patients with sepsis, whereas dynamic autoregulation was enhanced after LPS and impaired with a prolonged response time in patients. Hence, acute surges in blood pressure may adversely affect cerebral perfusion in patients with sepsis.

  1. Sensitivity Analysis for Dynamic Failure and Damage in Metallic Structures

    DTIC Science & Technology

    2005-03-01

    respect to the nominal alloy composition at the center of weld surface (Point 6 of Figure 7) -21 - U CO 2000 - * cE axc -2000 o" "....". . -401.11𔃺 1󈧄...Final Report Sensitivity Analysis for Dynamic Failure and Damage in Metallic Structures Office of Naval Research 800 North Quincy Street Arlington...3/31/05 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Sensitivity Analysis for Dynamic Failure and Damage in Metallic Structures Sb. GRANT NUMBER N000

  2. Network interface unit design options performance analysis

    NASA Technical Reports Server (NTRS)

    Miller, Frank W.

    1991-01-01

    An analysis is presented of three design options for the Space Station Freedom (SSF) onboard Data Management System (DMS) Network Interface Unit (NIU). The NIU provides the interface from the Fiber Distributed Data Interface (FDDI) local area network (LAN) to the DMS processing elements. The FDDI LAN provides the primary means for command and control and low and medium rate telemetry data transfers on board the SSF. The results of this analysis provide the basis for the implementation of the NIU.

  3. A performance analysis system for MEMS using automated imaging methods

    SciTech Connect

    LaVigne, G.F.; Miller, S.L.

    1998-08-01

    The ability to make in-situ performance measurements of MEMS operating at high speeds has been demonstrated using a new image analysis system. Significant improvements in performance and reliability have directly resulted from the use of this system.

  4. Dynamic analysis of load carriage biomechanics during level walking.

    PubMed

    Ren, Lei; Jones, Richard K; Howard, David

    2005-04-01

    This paper describes an investigation into the biomechanical effects of load carriage dynamics on human locomotion performance. A whole body, inverse dynamics gait model has been developed which uses only kinematic input data to define the gait cycle. To provide input data, three-dimensional gait measurements have been conducted to capture whole body motion while carrying a backpack. A nonlinear suspension model is employed to describe the backpack dynamics. The model parameters for a particular backpack system can be identified using a dynamic load carriage test-rig. Biomechanical assessments have been conducted based on combined gait and pack simulations. It was found that the backpack suspension stiffness and damping have little effect on human locomotion energetics. However, decreasing suspension stiffness offers important biomechanical advantages. The peak values of vertical pack force, acting on the trunk, and lower limb joint loads are all moderated. This would reduce shoulder strap pressures and the risk of injury when heavy loads are carried.

  5. Dynamic social network analysis using conversational dynamics in social networking and microblogging environments

    NASA Astrophysics Data System (ADS)

    Stocco, Gabriel; Savell, Robert; Cybenko, George

    2010-04-01

    In many security environments, the textual content of communications may be unavailable. In these instances, it is often desirable to infer the status of the network and its component entities from patterns of communication flow. Conversational dynamics among entities in the network may provide insight into important aspects of the underlying social network such as the formational dynamics of group structures, the active state of these groups, individuals' roles within groups, and the likelihood of individual participation in conversations. To gain insight into the use of conversational dynamics to facilitate Dynamic Social Network Analysis, we explore the use of interevent timings to associate entities in the Twitter social networking and micro-blogging environment. Specifically, we use message timings to establish inter-nodal relationships among participants. In addition, we demonstrate a new visualization technique for tracking levels of coordination or synchronization within the community via measures of socio-temporal coherence of the participants.

  6. An optical probe for micromachine performance analysis

    SciTech Connect

    Dickey, F.M.; Holswade, S.C.; Smith, N.F.; Miller, S.L.

    1997-01-01

    Understanding the mechanisms that impact the performance of Microelectromechanical Systems (MEMS) is essential to the development of optimized designs and fabrication processes, as well as the qualification of devices for commercial applications. Silicon micromachines include engines that consist of orthogonally oriented linear comb drive actuators mechanically connected to a rotating gear. These gears are as small as 50 {mu}m in diameter and can be driven at rotation rates exceeding 300,000 rpm. Optical techniques offer the potential for measuring long term statistical performance data and transient responses needed to optimize designs and manufacturing techniques. We describe the development of Micromachine Optical Probe (MOP) technology for the evaluation of micromachine performance. The MOP approach is based on the detection of optical signals scattered by the gear teeth or other physical structures. We present experimental results obtained with a prototype optical probe and micromachines developed at Sandia National Laboratories.

  7. Seismic performance analysis of Tendaho earth fill dam, Ethiopia.

    NASA Astrophysics Data System (ADS)

    Berhe, T.; Wu, W.

    2009-04-01

    The Tendaho dam is found in the Afar regional state, North Eastern part of Ethiopia. It is located within an area known as the ‘Tendaho Graben' ,which forms the center of Afar triangle, a low lying area of land where East African, Red sea and the Gulf of Eden Rift systems converge. The dam is an earthfill dam with a volume of about 4 Million cubic meters and with mixed clay core. The geological setting associated with the site of the dam, the geotechnical properties of the dam materials and seismicity of the region are reviewed. Based on this review, the foundation materials and dam body include some liquefiable granular soils. Moreover, the active East African Rift Valley fault, which can generate an earthquake of magnitude greater than 6, passes through the dam body. This valley is the primary seismic source contributing to the hazard at the Tendaho dam site. The availability of liquefiable materials beneath and within the dam body and the presence of the active fault crossing the dam site demand a thorough seismic analysis of the dam. The peak ground acceleration (PGA) is selected as a measure of ground motion severity. The PGA was selected according to the guidelines of the International Commission on Large Dams, ICOLD. Based on the criteria set by the ICOLD, the dam is analyzed for two different earthquake magnitudes, the Maximum Credible Earthquake (MCE) and the Operating Basis Earthquake (OBE). Numerical codes are useful tools to investigate the safety of dams in seismic prone areas. In this paper, FLAC3D numerical tool is used to investigate the performance of the dam under dynamic loading. Based on the numerical analysis, the seismic performance of the dam is investigated.

  8. Forecast analysis of optical waveguide bus performance

    NASA Technical Reports Server (NTRS)

    Ledesma, R.; Rourke, M. D.

    1979-01-01

    Elements to be considered in the design of a data bus include: architecture; data rate; modulation, encoding, detection; power distribution requirements; protocol, work structure; bus reliability, maintainability; interterminal transmission medium; cost; and others specific to application. Fiber- optic data bus considerations for a 32 port transmissive star architecture, are discussed in a tutorial format. General optical-waveguide bus concepts, are reviewed. The electrical and optical performance of a 32 port transmissive star bus, and the effects of temperature on the performance of optical-waveguide buses are examined. A bibliography of pertinent references and the bus receiver test results are included.

  9. Performance analysis of a VSAT network

    NASA Astrophysics Data System (ADS)

    Karam, Fouad G.; Miller, Neville; Karam, Antoine

    With the growing need for efficient satellite networking facilities, the very small aperture terminal (VSAT) technology emerges as the leading edge of satellite communications. Achieving the required performance of a VSAT network is dictated by the multiple access technique utilized. Determining the inbound access method best suited for a particular application involves trade-offs between response time and space segment utilization. In this paper, the slotted Aloha and dedicated stream access techniques are compared. It is shown that network performance is dependent on the traffic offered from remote earth stations as well as the sensitivity of customer's applications to satellite delay.

  10. Dynamic factor analysis for estimating ground water arsenic trends.

    PubMed

    Kuo, Yi-Ming; Chang, Fi-John

    2010-01-01

    Drinking ground water containing high arsenic (As) concentrations has been associated with blackfoot disease and the occurrence of cancer along the southwestern coast of Taiwan. As a result, 28 ground water observation wells were installed to monitor the ground water quality in this area. Dynamic factor analysis (DFA) is used to identify common trends that represent unexplained variability in ground water As concentrations of decommissioned wells and to investigate whether explanatory variables (total organic carbon [TOC], As, alkalinity, ground water elevation, and rainfall) affect the temporal variation in ground water As concentration. The results of the DFA show that rainfall dilutes As concentration in areas under aquacultural and agricultural use. Different combinations of geochemical variables (As, alkalinity, and TOC) of nearby monitoring wells affected the As concentrations of the most decommissioned wells. Model performance was acceptable for 11 wells (coefficient of efficiency >0.50), which represents 52% (11/21) of the decommissioned wells. Based on DFA results, we infer that surface water recharge may be effective for diluting the As concentration, especially in the areas that are relatively far from the coastline. We demonstrate that DFA can effectively identify the important factors and common effects representing unexplained variability common to decommissioned wells on As variation in ground water and extrapolate information from existing monitoring wells to the nearby decommissioned wells.

  11. Design of airborne wind turbine and computational fluid dynamics analysis

    NASA Astrophysics Data System (ADS)

    Anbreen, Faiqa

    Wind energy is a promising alternative to the depleting non-renewable sources. The height of the wind turbines becomes a constraint to their efficiency. Airborne wind turbine can reach much higher altitudes and produce higher power due to high wind velocity and energy density. The focus of this thesis is to design a shrouded airborne wind turbine, capable to generate 70 kW to propel a leisure boat with a capacity of 8-10 passengers. The idea of designing an airborne turbine is to take the advantage of higher velocities in the atmosphere. The Solidworks model has been analyzed numerically using Computational Fluid Dynamics (CFD) software StarCCM+. The Unsteady Reynolds Averaged Navier Stokes Simulation (URANS) with K-epsilon turbulence model has been selected, to study the physical properties of the flow, with emphasis on the performance of the turbine and the increase in air velocity at the throat. The analysis has been done using two ambient velocities of 12 m/s and 6 m/s. At 12 m/s inlet velocity, the velocity of air at the turbine has been recorded as 16 m/s. The power generated by the turbine is 61 kW. At inlet velocity of 6 m/s, the velocity of air at turbine increased to 10 m/s. The power generated by turbine is 25 kW.

  12. Fractal analysis on human dynamics of library loans

    NASA Astrophysics Data System (ADS)

    Fan, Chao; Guo, Jin-Li; Zha, Yi-Long

    2012-12-01

    In this paper, the fractal characteristic of human behaviors is investigated from the perspective of time series constructed with the amount of library loans. The values of the Hurst exponent and length of non-periodic cycle calculated through rescaled range analysis indicate that the time series of human behaviors and their sub-series are fractal with self-similarity and long-range dependence. Then the time series are converted into complex networks by the visibility algorithm. The topological properties of the networks such as scale-free property and small-world effect imply that there is a close relationship among the numbers of repetitious behaviors performed by people during certain periods of time. Our work implies that there is intrinsic regularity in the human collective repetitious behaviors. The conclusions may be helpful to develop some new approaches to investigate the fractal feature and mechanism of human dynamics, and provide some references for the management and forecast of human collective behaviors.

  13. Dynamic wake prediction and visualization with uncertainty analysis

    NASA Technical Reports Server (NTRS)

    Holforty, Wendy L. (Inventor); Powell, J. David (Inventor)

    2005-01-01

    A dynamic wake avoidance system utilizes aircraft and atmospheric parameters readily available in flight to model and predict airborne wake vortices in real time. A novel combination of algorithms allows for a relatively simple yet robust wake model to be constructed based on information extracted from a broadcast. The system predicts the location and movement of the wake based on the nominal wake model and correspondingly performs an uncertainty analysis on the wake model to determine a wake hazard zone (no fly zone), which comprises a plurality of wake planes, each moving independently from another. The system selectively adjusts dimensions of each wake plane to minimize spatial and temporal uncertainty, thereby ensuring that the actual wake is within the wake hazard zone. The predicted wake hazard zone is communicated in real time directly to a user via a realistic visual representation. In an example, the wake hazard zone is visualized on a 3-D flight deck display to enable a pilot to visualize or see a neighboring aircraft as well as its wake. The system substantially enhances the pilot's situational awareness and allows for a further safe decrease in spacing, which could alleviate airport and airspace congestion.

  14. Manufacturing in space: Fluid dynamics numerical analysis

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    Numerical computations were performed for natural convection in circular enclosures under various conditions of acceleration. It was found that subcritical acceleration vectors applied in the direction of the temperature gradient will lead to an eventual state of rest regardless of the initial state of motion. Supercritical acceleration vectors will lead to the same steady state condition of motion regardless of the initial state of motion. Convection velocities were computed for acceleration vectors at various angles of the initial temperature gradient. The results for Rayleigh numbers of 1000 or less were found to closely follow Weinbaum's first order theory. Higher Rayleigh number results were shown to depart significantly from the first order theory. Supercritical behavior was confirmed for Rayleigh numbers greater than the known supercritical value of 9216. Response times were determined to provide an indication of the time required to change states of motion for the various cases considered.

  15. Operationalizing sustainability in urban coastal systems: a system dynamics analysis.

    PubMed

    Mavrommati, Georgia; Bithas, Kostas; Panayiotidis, Panayiotis

    2013-12-15

    We propose a system dynamics approach for Ecologically Sustainable Development (ESD) in urban coastal systems. A systematic analysis based on theoretical considerations, policy analysis and experts' knowledge is followed in order to define the concept of ESD. The principles underlying ESD feed the development of a System Dynamics Model (SDM) that connects the pollutant loads produced by urban systems' socioeconomic activities with the ecological condition of the coastal ecosystem that it is delineated in operational terms through key biological elements defined by the EU Water Framework Directive. The receiving waters of the Athens Metropolitan area, which bears the elements of typical high population density Mediterranean coastal city but which currently has also new dynamics induced by the ongoing financial crisis, are used as an experimental system for testing a system dynamics approach to apply the concept of ESD. Systems' thinking is employed to represent the complex relationships among the components of the system. Interconnections and dependencies that determine the potentials for achieving ESD are revealed. The proposed system dynamics analysis can facilitate decision makers to define paths of development that comply with the principles of ESD.

  16. Nonlinear dynamic characteristic analysis of jointed beam with clearance

    NASA Astrophysics Data System (ADS)

    Zhang, Jing; Guo, Hong-Wei; Liu, Rong-Qiang; Wu, Juan; Kou, Zi-Ming; Deng, Zong-Quan

    2016-12-01

    The impact and elasticity of discontinuous beams with clearance frequently affect the dynamic response of structures used in space missions. This study investigates the dynamic response of jointed beams which are the periodic units of deployable structures. The vibration process of jointed beams includes free-play and impact stages. A method for the dynamic analysis of jointed beams with clearance is proposed based on mode superposition and instantaneous static deformation. Transfer matrix, which expresses the relationship of the responses before and after the impact of jointed beams, is derived to calculate the response of the jointed beams after a critical position. The dynamic responses of jointed beams are then simulated. The effects of various parameters on the displacement and velocity of beams are investigated.

  17. Digital data processing system dynamic loading analysis

    NASA Technical Reports Server (NTRS)

    Lagas, J. J.; Peterka, J. J.; Tucker, A. E.

    1976-01-01

    Simulation and analysis of the Space Shuttle Orbiter Digital Data Processing System (DDPS) are reported. The mated flight and postseparation flight phases of the space shuttle's approach and landing test configuration were modeled utilizing the Information Management System Interpretative Model (IMSIM) in a computerized simulation modeling of the ALT hardware, software, and workload. System requirements simulated for the ALT configuration were defined. Sensitivity analyses determined areas of potential data flow problems in DDPS operation. Based on the defined system requirements and the sensitivity analyses, a test design is described for adapting, parameterizing, and executing the IMSIM. Varying load and stress conditions for the model execution are given. The analyses of the computer simulation runs were documented as results, conclusions, and recommendations for DDPS improvements.

  18. Preliminary analysis of turbochargers rotors dynamic behaviour

    NASA Astrophysics Data System (ADS)

    Monoranu, R.; Ştirbu, C.; Bujoreanu, C.

    2016-08-01

    Turbocharger rotors for the spark and compression ignition engines are resistant steels manufactured in order to support the exhaust gas temperatures exceeding 1200 K. In fact, the mechanical stress is not large as the power consumption of these systems is up to 10 kW, but the operating speeds are high, ranging between 30000 ÷ 250000 rpm. Therefore, the correct turbochargers functioning involves, even from the design stage, the accurate evaluation of the temperature effects, of the turbine torque due to the engine exhaust gases and of the vibration system behaviour caused by very high operating speeds. In addition, the turbocharger lubrication complicates the model, because the classical hydrodynamic theory cannot be applied to evaluate the floating bush bearings. The paper proposes a FEM study using CATIA environment, both as modeling medium and as tool for the numerical analysis, in order to highlight the turbocharger complex behaviour. An accurate design may prevent some major issues which can occur during its operation.

  19. Applying Mechanics to Swimming Performance Analysis.

    ERIC Educational Resources Information Center

    Barthels, Katharine

    1989-01-01

    Swimming teachers and coaches can improve their feedback to swimmers, when correcting or refining swim movements, by applying some basic biomechanical concepts relevant to swimming. This article focuses on the biomechanical considerations used in analyzing swimming performance. Techniques for spotting and correcting problems that impede…

  20. Cognitive Performance: A Model for Analysis

    ERIC Educational Resources Information Center

    Marjoribanks, Kevin

    1975-01-01

    In the present study, cognitive performance was examined by analysing a path model which included family environment variables, social status indicators, and a set of enabling conditions consisting of self-esteem, attitudes toward schoolwork and educational and occupational aspirations. (Editor)