Noise estimation of beam position monitors at RHIC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, X.; Bai, M.; Lee, S. Y.

2014-02-10

Beam position monitors (BPM) are used to record the average orbits and transverse turn-by-turn displacements of the beam centroid motion. The Relativistic Hadron Ion Collider (RHIC) has 160 BPMs for each plane in each of the Blue and Yellow rings: 72 dual-plane BPMs in the insertion regions (IR) and 176 single-plane modules in the arcs. Each BPM is able to acquire 1024 or 4096 consecutive turn-by-turn beam positions. Inevitably, there are broadband noisy signals in the turn-by-turn data due to BPM electronics as well as other sources. A detailed study of the BPM noise performance is critical for reliable opticsmore » measurement and beam dynamics analysis based on turn-by-turn data.« less

Autonomous Navigation of Small Uavs Based on Vehicle Dynamic Model

NASA Astrophysics Data System (ADS)

Khaghani, M.; Skaloud, J.

2016-03-01

This paper presents a novel approach to autonomous navigation for small UAVs, in which the vehicle dynamic model (VDM) serves as the main process model within the navigation filter. The proposed method significantly increases the accuracy and reliability of autonomous navigation, especially for small UAVs with low-cost IMUs on-board. This is achieved with no extra sensor added to the conventional INS/GNSS setup. This improvement is of special interest in case of GNSS outages, where inertial coasting drifts very quickly. In the proposed architecture, the solution to VDM equations provides the estimate of position, velocity, and attitude, which is updated within the navigation filter based on available observations, such as IMU data or GNSS measurements. The VDM is also fed with the control input to the UAV, which is available within the control/autopilot system. The filter is capable of estimating wind velocity and dynamic model parameters, in addition to navigation states and IMU sensor errors. Monte Carlo simulations reveal major improvements in navigation accuracy compared to conventional INS/GNSS navigation system during the autonomous phase, when satellite signals are not available due to physical obstruction or electromagnetic interference for example. In case of GNSS outages of a few minutes, position and attitude accuracy experiences improvements of orders of magnitude compared to inertial coasting. It means that during such scenario, the position-velocity-attitude (PVA) determination is sufficiently accurate to navigate the UAV to a home position without any signal that depends on vehicle environment.

Validation of instrumentation to monitor dynamic performance of olympic weightlifters.

PubMed

Bruenger, Adam J; Smith, Sarah L; Sands, William A; Leigh, Michael R

2007-05-01

The purpose of this study was to validate the accuracy and reliability of the Weightlifting Video Overlay System (WVOS) used by coaches and sport biomechanists at the United States Olympic Training Center. Static trials with the bar set at specific positions and dynamic trials of a power snatch were performed. Static and dynamic values obtained by the WVOS were compared with values obtained by tape measure and standard video kinematic analysis. Coordinate positions (horizontal [X] and vertical [Y]) were compared on both ends (left and right) of the bar. Absolute technical error of measurement between WVOS and kinematic values were calculated (0.97 cm [left X], 0.98 cm [right X], 0.88 cm [left Y], and 0.53 cm [right Y]) for the static data. Pearson correlations for all dynamic trials exceeded r = 0.88. The greatest discrepancies between the 2 measuring systems were found to occur when there was twisting of the bar during the performance. This error was probably due to the location on the bar where the coordinates were measured. The WVOS appears to provide accurate position information when compared with standard kinematics; however, care must be taken in evaluating position measurements if there is a significant amount of twisting in the movement. The WVOS appears to be reliable and valid within reasonable error limits for the determination of weightlifting movement technique.

Lane-Level Vehicle Positioning : Integrating Diverse Systems for Precision and Reliability

DOT National Transportation Integrated Search

2013-05-13

Integrated global positioning system/inertial navigation system (GPS/INS) technology, the backbone of vehicle positioning systems, cannot provide the precision and reliability needed for vehicle-based, lane-level positioning in all driving environmen...

Development of a clinical static and dynamic standing balance measurement tool appropriate for use in adolescents.

PubMed

Emery, Carolyn A; Cassidy, J David; Klassen, Terry P; Rosychuk, Rhonda J; Rowe, Brian B

2005-06-01

There is a need in sports medicine for a static and dynamic standing balance measure to quantify balance ability in adolescents. The purposes of this study were to determine the test-retest reliability of timed static (eyes open) and dynamic (eyes open and eyes closed) unipedal balance measurements and to examine factors associated with balance. Adolescents (n=123) were randomly selected from 10 Calgary high schools. This study used a repeated-measures design. One rater measured unipedal standing balance, including timed eyes-closed static (ECS), eyes-open dynamic (EOD), and eyes-closed dynamic (ECD) balance at baseline and 1 week later. Dynamic balance was measured on a foam surface. Reliability was examined using both intraclass correlation coefficients (ICCs) and Bland and Altman statistical techniques. Multiple linear regressions were used to examine other potentially influencing factors. Based on ICCs, test-retest reliability was adequate for ECS, EOD, and ECD balance (ICC=.69, .59, and .46, respectively). The results of Bland and Altman methods, however, suggest that caution is required in interpreting reliability based on ICCs alone. Although both ECS balance and ECD balance appear to demonstrate adequate test-retest reliability by ICC, Bland and Altman methods of agreement demonstrate sufficient reliability for ECD balance only. Thirty percent of the subjects reached the 180-second maximum on EOD balance, suggesting that this test is not appropriate for use in this population. Balance ability (ECS and ECD) was better in adolescents with no past history of lower-extremity injury. Timed ECD balance is an appropriate and reliable clinical measurement for use in adolescents and is influenced by previous injury.

A Timing Estimation Method Based-on Skewness Analysis in Vehicular Wireless Networks.

PubMed

Cui, Xuerong; Li, Juan; Wu, Chunlei; Liu, Jian-Hang

2015-11-13

Vehicle positioning technology has drawn more and more attention in vehicular wireless networks to reduce transportation time and traffic accidents. Nowadays, global navigation satellite systems (GNSS) are widely used in land vehicle positioning, but most of them are lack precision and reliability in situations where their signals are blocked. Positioning systems base-on short range wireless communication are another effective way that can be used in vehicle positioning or vehicle ranging. IEEE 802.11p is a new real-time short range wireless communication standard for vehicles, so a new method is proposed to estimate the time delay or ranges between vehicles based on the IEEE 802.11p standard which includes three main steps: cross-correlation between the received signal and the short preamble, summing up the correlated results in groups, and finding the maximum peak using a dynamic threshold based on the skewness analysis. With the range between each vehicle or road-side infrastructure, the position of neighboring vehicles can be estimated correctly. Simulation results were presented in the International Telecommunications Union (ITU) vehicular multipath channel, which show that the proposed method provides better precision than some well-known timing estimation techniques, especially in low signal to noise ratio (SNR) environments.

Radioisotope Power System Pool Concept

NASA Technical Reports Server (NTRS)

Rusick, Jeffrey J.; Bolotin, Gary S.

2015-01-01

Advanced Radioisotope Power Systems (RPS) for NASA deep space science missions have historically used static thermoelectric-based designs because they are highly reliable, and their radioisotope heat sources can be passively cooled throughout the mission life cycle. Recently, a significant effort to develop a dynamic RPS, the Advanced Stirling Radioisotope Generator (ASRG), was conducted by NASA and the Department of Energy, because Stirling based designs offer energy conversion efficiencies four times higher than heritage thermoelectric designs; and the efficiency would proportionately reduce the amount of radioisotope fuel needed for the same power output. However, the long term reliability of a Stirling based design is a concern compared to thermoelectric designs, because for certain Stirling system architectures the radioisotope heat sources must be actively cooled via the dynamic operation of Stirling converters throughout the mission life cycle. To address this reliability concern, a new dynamic Stirling cycle RPS architecture is proposed called the RPS Pool Concept.

Garter snake population dynamics from a 16-year study: considerations for ecological monitoring

Treesearch

Amy J. Lind; Hartwell H. Welsh Jr; David A. Tallmon

2005-01-01

Snakes have recently been proposed as model organisms for addressing both evolutionary and ecological questions. Because of their middle position in many food webs they may be useful indicators of trophic complexity and dynamics. However, reliable data on snake populations are rare due to the challenges of sampling these patchily distributed, cryptic, and often...

Large-scale systems: Complexity, stability, reliability

NASA Technical Reports Server (NTRS)

Siljak, D. D.

1975-01-01

After showing that a complex dynamic system with a competitive structure has highly reliable stability, a class of noncompetitive dynamic systems for which competitive models can be constructed is defined. It is shown that such a construction is possible in the context of the hierarchic stability analysis. The scheme is based on the comparison principle and vector Liapunov functions.

Bayesian integration of position and orientation cues in perception of biological and non-biological forms.

PubMed

Thurman, Steven M; Lu, Hongjing

2014-01-01

Visual form analysis is fundamental to shape perception and likely plays a central role in perception of more complex dynamic shapes, such as moving objects or biological motion. Two primary form-based cues serve to represent the overall shape of an object: the spatial position and the orientation of locations along the boundary of the object. However, it is unclear how the visual system integrates these two sources of information in dynamic form analysis, and in particular how the brain resolves ambiguities due to sensory uncertainty and/or cue conflict. In the current study, we created animations of sparsely-sampled dynamic objects (human walkers or rotating squares) comprised of oriented Gabor patches in which orientation could either coincide or conflict with information provided by position cues. When the cues were incongruent, we found a characteristic trade-off between position and orientation information whereby position cues increasingly dominated perception as the relative uncertainty of orientation increased and vice versa. Furthermore, we found no evidence for differences in the visual processing of biological and non-biological objects, casting doubt on the claim that biological motion may be specialized in the human brain, at least in specific terms of form analysis. To explain these behavioral results quantitatively, we adopt a probabilistic template-matching model that uses Bayesian inference within local modules to estimate object shape separately from either spatial position or orientation signals. The outputs of the two modules are integrated with weights that reflect individual estimates of subjective cue reliability, and integrated over time to produce a decision about the perceived dynamics of the input data. Results of this model provided a close fit to the behavioral data, suggesting a mechanism in the human visual system that approximates rational Bayesian inference to integrate position and orientation signals in dynamic form analysis.

Girsanov's transformation based variance reduced Monte Carlo simulation schemes for reliability estimation in nonlinear stochastic dynamics

NASA Astrophysics Data System (ADS)

Kanjilal, Oindrila; Manohar, C. S.

2017-07-01

The study considers the problem of simulation based time variant reliability analysis of nonlinear randomly excited dynamical systems. Attention is focused on importance sampling strategies based on the application of Girsanov's transformation method. Controls which minimize the distance function, as in the first order reliability method (FORM), are shown to minimize a bound on the sampling variance of the estimator for the probability of failure. Two schemes based on the application of calculus of variations for selecting control signals are proposed: the first obtains the control force as the solution of a two-point nonlinear boundary value problem, and, the second explores the application of the Volterra series in characterizing the controls. The relative merits of these schemes, vis-à-vis the method based on ideas from the FORM, are discussed. Illustrative examples, involving archetypal single degree of freedom (dof) nonlinear oscillators, and a multi-degree of freedom nonlinear dynamical system, are presented. The credentials of the proposed procedures are established by comparing the solutions with pertinent results from direct Monte Carlo simulations.

Rollover risk prediction of heavy vehicles by reliability index and empirical modelling

NASA Astrophysics Data System (ADS)

Sellami, Yamine; Imine, Hocine; Boubezoul, Abderrahmane; Cadiou, Jean-Charles

2018-03-01

This paper focuses on a combination of a reliability-based approach and an empirical modelling approach for rollover risk assessment of heavy vehicles. A reliability-based warning system is developed to alert the driver to a potential rollover before entering into a bend. The idea behind the proposed methodology is to estimate the rollover risk by the probability that the vehicle load transfer ratio (LTR) exceeds a critical threshold. Accordingly, a so-called reliability index may be used as a measure to assess the vehicle safe functioning. In the reliability method, computing the maximum of LTR requires to predict the vehicle dynamics over the bend which can be in some cases an intractable problem or time-consuming. With the aim of improving the reliability computation time, an empirical model is developed to substitute the vehicle dynamics and rollover models. This is done by using the SVM (Support Vector Machines) algorithm. The preliminary obtained results demonstrate the effectiveness of the proposed approach.

Achieving Reliable Communication in Dynamic Emergency Responses

PubMed Central

Chipara, Octav; Plymoth, Anders N.; Liu, Fang; Huang, Ricky; Evans, Brian; Johansson, Per; Rao, Ramesh; Griswold, William G.

2011-01-01

Emergency responses require the coordination of first responders to assess the condition of victims, stabilize their condition, and transport them to hospitals based on the severity of their injuries. WIISARD is a system designed to facilitate the collection of medical information and its reliable dissemination during emergency responses. A key challenge in WIISARD is to deliver data with high reliability as first responders move and operate in a dynamic radio environment fraught with frequent network disconnections. The initial WIISARD system employed a client-server architecture and an ad-hoc routing protocol was used to exchange data. The system had low reliability when deployed during emergency drills. In this paper, we identify the underlying causes of unreliability and propose a novel peer-to-peer architecture that in combination with a gossip-based communication protocol achieves high reliability. Empirical studies show that compared to the initial WIISARD system, the redesigned system improves reliability by as much as 37% while reducing the number of transmitted packets by 23%. PMID:22195075

Performance Analysis on Carrier Phase-Based Tightly-Coupled GPS/BDS/INS Integration in GNSS Degraded and Denied Environments

PubMed Central

Han, Houzeng; Wang, Jian; Wang, Jinling; Tan, Xinglong

2015-01-01

The integration of Global Navigation Satellite Systems (GNSS) carrier phases with Inertial Navigation System (INS) measurements is essential to provide accurate and continuous position, velocity and attitude information, however it is necessary to fix ambiguities rapidly and reliably to obtain high accuracy navigation solutions. In this paper, we present the notion of combining the Global Positioning System (GPS), the BeiDou Navigation Satellite System (BDS) and low-cost micro-electro-mechanical sensors (MEMS) inertial systems for reliable navigation. An adaptive multipath factor-based tightly-coupled (TC) GPS/BDS/INS integration algorithm is presented and the overall performance of the integrated system is illustrated. A twenty seven states TC GPS/BDS/INS model is adopted with an extended Kalman filter (EKF), which is carried out by directly fusing ambiguity fixed double-difference (DD) carrier phase measurements with the INS predicted pseudoranges to estimate the error states. The INS-aided integer ambiguity resolution (AR) strategy is developed by using a dynamic model, a two-step estimation procedure is applied with adaptively estimated covariance matrix to further improve the AR performance. A field vehicular test was carried out to demonstrate the positioning performance of the combined system. The results show the TC GPS/BDS/INS system significantly improves the single-epoch AR reliability as compared to that of GPS/BDS-only or single satellite navigation system integrated strategy, especially for high cut-off elevations. The AR performance is also significantly improved for the combined system with adaptive covariance matrix in the presence of low elevation multipath related to the GNSS-only case. A total of fifteen simulated outage tests also show that the time to relock of the GPS/BDS signals is shortened, which improves the system availability. The results also indicate that TC integration system achieves a few centimeters accuracy in positioning based on the comparison analysis and covariance analysis, even in harsh environments (e.g., in urban canyons), thus we can see the advantage of positioning at high cut-off elevations that the combined GPS/BDS brings. PMID:25875191

Performance analysis on carrier phase-based tightly-coupled GPS/BDS/INS integration in GNSS degraded and denied environments.

PubMed

Han, Houzeng; Wang, Jian; Wang, Jinling; Tan, Xinglong

2015-04-14

The integration of Global Navigation Satellite Systems (GNSS) carrier phases with Inertial Navigation System (INS) measurements is essential to provide accurate and continuous position, velocity and attitude information, however it is necessary to fix ambiguities rapidly and reliably to obtain high accuracy navigation solutions. In this paper, we present the notion of combining the Global Positioning System (GPS), the BeiDou Navigation Satellite System (BDS) and low-cost micro-electro-mechanical sensors (MEMS) inertial systems for reliable navigation. An adaptive multipath factor-based tightly-coupled (TC) GPS/BDS/INS integration algorithm is presented and the overall performance of the integrated system is illustrated. A twenty seven states TC GPS/BDS/INS model is adopted with an extended Kalman filter (EKF), which is carried out by directly fusing ambiguity fixed double-difference (DD) carrier phase measurements with the INS predicted pseudoranges to estimate the error states. The INS-aided integer ambiguity resolution (AR) strategy is developed by using a dynamic model, a two-step estimation procedure is applied with adaptively estimated covariance matrix to further improve the AR performance. A field vehicular test was carried out to demonstrate the positioning performance of the combined system. The results show the TC GPS/BDS/INS system significantly improves the single-epoch AR reliability as compared to that of GPS/BDS-only or single satellite navigation system integrated strategy, especially for high cut-off elevations. The AR performance is also significantly improved for the combined system with adaptive covariance matrix in the presence of low elevation multipath related to the GNSS-only case. A total of fifteen simulated outage tests also show that the time to relock of the GPS/BDS signals is shortened, which improves the system availability. The results also indicate that TC integration system achieves a few centimeters accuracy in positioning based on the comparison analysis and covariance analysis, even in harsh environments (e.g., in urban canyons), thus we can see the advantage of positioning at high cut-off elevations that the combined GPS/BDS brings.

Reliability modelling and analysis of a multi-state element based on a dynamic Bayesian network

NASA Astrophysics Data System (ADS)

Li, Zhiqiang; Xu, Tingxue; Gu, Junyuan; Dong, Qi; Fu, Linyu

2018-04-01

This paper presents a quantitative reliability modelling and analysis method for multi-state elements based on a combination of the Markov process and a dynamic Bayesian network (DBN), taking perfect repair, imperfect repair and condition-based maintenance (CBM) into consideration. The Markov models of elements without repair and under CBM are established, and an absorbing set is introduced to determine the reliability of the repairable element. According to the state-transition relations between the states determined by the Markov process, a DBN model is built. In addition, its parameters for series and parallel systems, namely, conditional probability tables, can be calculated by referring to the conditional degradation probabilities. Finally, the power of a control unit in a failure model is used as an example. A dynamic fault tree (DFT) is translated into a Bayesian network model, and subsequently extended to a DBN. The results show the state probabilities of an element and the system without repair, with perfect and imperfect repair, and under CBM, with an absorbing set plotted by differential equations and verified. Through referring forward, the reliability value of the control unit is determined in different kinds of modes. Finally, weak nodes are noted in the control unit.

A hybrid smartphone indoor positioning solution for mobile LBS.

PubMed

Liu, Jingbin; Chen, Ruizhi; Pei, Ling; Guinness, Robert; Kuusniemi, Heidi

2012-12-12

Smartphone positioning is an enabling technology used to create new business in the navigation and mobile location-based services (LBS) industries. This paper presents a smartphone indoor positioning engine named HIPE that can be easily integrated with mobile LBS. HIPE is a hybrid solution that fuses measurements of smartphone sensors with wireless signals. The smartphone sensors are used to measure the user's motion dynamics information (MDI), which represent the spatial correlation of various locations. Two algorithms based on hidden Markov model (HMM) problems, the grid-based filter and the Viterbi algorithm, are used in this paper as the central processor for data fusion to resolve the position estimates, and these algorithms are applicable for different applications, e.g., real-time navigation and location tracking, respectively. HIPE is more widely applicable for various motion scenarios than solutions proposed in previous studies because it uses no deterministic motion models, which have been commonly used in previous works. The experimental results showed that HIPE can provide adequate positioning accuracy and robustness for different scenarios of MDI combinations. HIPE is a cost-efficient solution, and it can work flexibly with different smartphone platforms, which may have different types of sensors available for the measurement of MDI data. The reliability of the positioning solution was found to increase with increasing precision of the MDI data.

RELIABILITY AND VALIDITY OF A BIOMECHANICALLY BASED ANALYSIS METHOD FOR THE TENNIS SERVE

PubMed Central

Kibler, W. Ben; Lamborn, Leah; Smith, Belinda J.; English, Tony; Jacobs, Cale; Uhl, Tim L.

2017-01-01

Background An observational tennis serve analysis (OTSA) tool was developed using previously established body positions from three-dimensional kinematic motion analysis studies. These positions, defined as nodes, have been associated with efficient force production and minimal joint loading. However, the tool has yet to be examined scientifically. Purpose The primary purpose of this investigation was to determine the inter-observer reliability for each node between two health care professionals (HCPs) that developed the OTSA, and secondarily to investigate the validity of the OTSA. Methods Two separate studies were performed to meet these objectives. An inter-observer reliability study preceded the validity study by examining 28 videos of players serving. Two HCPs graded each video and scored the presence or absence of obtaining each node. Discriminant validity was determined in 33 tennis players using video taped records of three first serves. Serve mechanics were graded using the OSTA and categorized players into those with good ( ≥ 5) and poor ( ≤ 4) mechanics. Participants performed a series of field tests to evaluate trunk flexibility, lower extremity and trunk power, and dynamic balance. Results The group with good mechanics demonstrated greater backward trunk flexibility (p=0.02), greater rotational power (p=0.02), and higher single leg countermovement jump (p=0.05). Reliability of the OTSA ranged from K = 0.36-1.0, with the majority of all the nodes displaying substantial reliability (K>0.61). Conclusion This study provides HCPs with a valid and reliable field tool used to assess serve mechanics. Physical characteristics of trunk mobility and power appear to discriminate serve mechanics between players. Future intervention studies are needed to determine if improvement in physical function contribute to improved serve mechanics. Level of Evidence 3 PMID:28593098

Reliability of Performance-Based Clinical Measurements to Assess Shoulder Girdle Kinematics and Positioning: Systematic Review.

PubMed

D'hondt, Norman E; Kiers, Henri; Pool, Jan J M; Hacquebord, Sijmen T; Terwee, Caroline B; Veeger, Dirkjan H E J

2017-01-01

Deviant shoulder girdle movement is suggested as an eminent factor in the etiology of shoulder pain. Reliable measurements of shoulder girdle kinematics are a prerequisite for optimizing clinical management strategies. The purpose of this study was to evaluate the reliability, measurement error, and internal consistency of measurements with performance-based clinical tests for shoulder girdle kinematics and positioning in patients with shoulder pain. The MEDLINE, Embase, CINAHL, and SPORTDiscus databases were systematically searched from inception to August 2015. Articles published in Dutch, English, or German were included if they involved the evaluation of at least one of the measurement properties of interest. Two reviewers independently evaluated the methodological quality per studied measurement property with the 4-point-rating scale of the COSMIN (COnsensus-based Standards for the selection of health Measurement INstruments) checklist, extracted data, and assessed the adequacy of the measurement properties. Forty studies comprising more than 30 clinical tests were included. Actual reported measurements of the tests were categorized into: (1) positional measurement methods, (2) measurement methods to determine dynamic characteristics, and (3) tests to diagnose impairments of shoulder girdle function. Best evidence synthesis of the tests was performed per measurement for each measurement property. All studies had significant limitations, including incongruence between test description and actual reported measurements and a lack of reporting on minimal important change. In general, the methodological quality of the selected studies was fair to poor. High-quality evidence indicates that measurements obtained with the Modified Scapular Assistance Test are not reliable for clinical use. Sound recommendations for the use of other tests could not be made due to inadequate evidence. Across studies, diversity in description, performance, and interpretation of similar tests was present, and different criteria were used to establish similar diagnoses, mostly without taking into account a clinically meaningful context. Consequently, these tests lack face validity, which hampers their clinical use. Further research on validity and how to integrate a clinically meaningful context of movement into clinical tests is warranted. © 2017 American Physical Therapy Association

Integrating molecular dynamics and co-evolutionary analysis for reliable target prediction and deregulation of the allosteric inhibition of aspartokinase for amino acid production.

PubMed

Chen, Zhen; Rappert, Sugima; Sun, Jibin; Zeng, An-Ping

2011-07-20

Deregulation of allosteric inhibition of enzymes is a challenge for strain engineering and has been achieved so far primarily by random mutation and trial-and-error. In this work, we used aspartokinase, an important allosteric enzyme for industrial amino acids production, to demonstrate a predictive approach that combines protein dynamics and evolution for a rational reengineering of enzyme allostery. Molecular dynamic simulation of aspartokinase III (AK3) from Escherichia coli and statistical coupling analysis of protein sequences of the aspartokinase family allowed to identify a cluster of residues which are correlated during protein motion and coupled during the evolution. This cluster of residues forms an interconnected network mediating the allosteric regulation, including most of the previously reported positions mutated in feedback insensitive AK3 mutants. Beyond these mutation positions, we have successfully constructed another twelve targeted mutations of AK3 desensitized toward lysine inhibition. Six threonine-insensitive mutants of aspartokinase I-homoserine dehydrogenase I (AK1-HD1) were also created based on the predictions. The proposed approach can be widely applied for the deregulation of other allosteric enzymes. Copyright © 2011 Elsevier B.V. All rights reserved.

Social humanoid robot SARA: development of the wrist mechanism

NASA Astrophysics Data System (ADS)

Penčić, M.; Rackov, M.; Čavić, M.; Kiss, I.; Cioată, V. G.

2018-01-01

This paper presents the development of a wrist mechanism for humanoid robots. The research was conducted within the project which develops social humanoid robot Sara - a mobile anthropomorphic platform for researching the social behaviour of robots. There are two basic ways for the realization of humanoid wrist. The first one is based on biologically inspired structures that have variable stiffness, and the second one on low backlash mechanisms that have high stiffness. Our solution is low backlash differential mechanism that requires small actuators. Based on the kinematic-dynamic requirements, a dynamic model of the robot wrist is formed. A dynamic simulation for several hand positions was performed and the driving torques of the wrist mechanism were determined. The realized wrist has 2 DOFs and enables movements in the direction of flexion/extension 115°, ulnar/radial deviation ±45° and the combination of these two movements. It consists of a differential mechanism with three spur bevel gears, two of which are driving and identical, while the last one is the driven gear to which the robot hand is attached. Power transmission and motion from the actuator to the input links of the differential mechanism is realized with two parallel placed identical gear mechanisms. The wrist mechanism has high carrying capacity and reliability, high efficiency, a compact design and low backlash that provides high positioning accuracy and repeatability of movements, which is essential for motion control.

A motor speech assessment for children with severe speech disorders: reliability and validity evidence.

PubMed

Strand, Edythe A; McCauley, Rebecca J; Weigand, Stephen D; Stoeckel, Ruth E; Baas, Becky S

2013-04-01

In this article, the authors report reliability and validity evidence for the Dynamic Evaluation of Motor Speech Skill (DEMSS), a new test that uses dynamic assessment to aid in the differential diagnosis of childhood apraxia of speech (CAS). Participants were 81 children between 36 and 79 months of age who were referred to the Mayo Clinic for diagnosis of speech sound disorders. Children were given the DEMSS and a standard speech and language test battery as part of routine evaluations. Subsequently, intrajudge, interjudge, and test-retest reliability were evaluated for a subset of participants. Construct validity was explored for all 81 participants through the use of agglomerative cluster analysis, sensitivity measures, and likelihood ratios. The mean percentage of agreement for 171 judgments was 89% for test-retest reliability, 89% for intrajudge reliability, and 91% for interjudge reliability. Agglomerative hierarchical cluster analysis showed that total DEMSS scores largely differentiated clusters of children with CAS vs. mild CAS vs. other speech disorders. Positive and negative likelihood ratios and measures of sensitivity and specificity suggested that the DEMSS does not overdiagnose CAS but sometimes fails to identify children with CAS. The value of the DEMSS in differential diagnosis of severe speech impairments was supported on the basis of evidence of reliability and validity.

Reliability modelling and analysis of a multi-state element based on a dynamic Bayesian network

PubMed Central

Xu, Tingxue; Gu, Junyuan; Dong, Qi; Fu, Linyu

2018-01-01

This paper presents a quantitative reliability modelling and analysis method for multi-state elements based on a combination of the Markov process and a dynamic Bayesian network (DBN), taking perfect repair, imperfect repair and condition-based maintenance (CBM) into consideration. The Markov models of elements without repair and under CBM are established, and an absorbing set is introduced to determine the reliability of the repairable element. According to the state-transition relations between the states determined by the Markov process, a DBN model is built. In addition, its parameters for series and parallel systems, namely, conditional probability tables, can be calculated by referring to the conditional degradation probabilities. Finally, the power of a control unit in a failure model is used as an example. A dynamic fault tree (DFT) is translated into a Bayesian network model, and subsequently extended to a DBN. The results show the state probabilities of an element and the system without repair, with perfect and imperfect repair, and under CBM, with an absorbing set plotted by differential equations and verified. Through referring forward, the reliability value of the control unit is determined in different kinds of modes. Finally, weak nodes are noted in the control unit. PMID:29765629

Reliability of digital reactor protection system based on extenics.

PubMed

Zhao, Jing; He, Ya-Nan; Gu, Peng-Fei; Chen, Wei-Hua; Gao, Feng

2016-01-01

After the Fukushima nuclear accident, safety of nuclear power plants (NPPs) is widespread concerned. The reliability of reactor protection system (RPS) is directly related to the safety of NPPs, however, it is difficult to accurately evaluate the reliability of digital RPS. The method is based on estimating probability has some uncertainties, which can not reflect the reliability status of RPS dynamically and support the maintenance and troubleshooting. In this paper, the reliability quantitative analysis method based on extenics is proposed for the digital RPS (safety-critical), by which the relationship between the reliability and response time of RPS is constructed. The reliability of the RPS for CPR1000 NPP is modeled and analyzed by the proposed method as an example. The results show that the proposed method is capable to estimate the RPS reliability effectively and provide support to maintenance and troubleshooting of digital RPS system.

Development and positioning reliability of a TMS coil holder for headache research.

PubMed

Chronicle, Edward P; Pearson, A Jane; Matthews, Cheryl

2005-01-01

Accurate and reproducible coil positioning is important for headache research using transcranial magnetic stimulation protocols. We aimed to design a transcranial magnetic stimulation coil holder and demonstrate reliability of test-retest coil positioning. A coil holder was developed and manufactured according to three principles of stability, durability, and three-dimensional positional accuracy. Reliability of coil positioning was assessed by stimulating over the motor cortex of four neurologically normal subjects and recording finger muscle responses, both at a test phase and a retest phase several hours later. In all four subjects, repositioning of the transcranial magnetic stimulation coil solely on the basis of coil holder coordinates was accurate to within 2 mm. The coil holder demonstrated good test-retest reliability of coil positioning, and is thus a promising tool for transcranial magnetic stimulation-based headache research, particularly studies of prophylactic drug effect where several laboratory visits with identical coil positioning are necessary.

High-precision real-time 3D shape measurement based on a quad-camera system

NASA Astrophysics Data System (ADS)

Tao, Tianyang; Chen, Qian; Feng, Shijie; Hu, Yan; Zhang, Minliang; Zuo, Chao

2018-01-01

Phase-shifting profilometry (PSP) based 3D shape measurement is well established in various applications due to its high accuracy, simple implementation, and robustness to environmental illumination and surface texture. In PSP, higher depth resolution generally requires higher fringe density of projected patterns which, in turn, lead to severe phase ambiguities that must be solved with additional information from phase coding and/or geometric constraints. However, in order to guarantee the reliability of phase unwrapping, available techniques are usually accompanied by increased number of patterns, reduced amplitude of fringe, and complicated post-processing algorithms. In this work, we demonstrate that by using a quad-camera multi-view fringe projection system and carefully arranging the relative spatial positions between the cameras and the projector, it becomes possible to completely eliminate the phase ambiguities in conventional three-step PSP patterns with high-fringe-density without projecting any additional patterns or embedding any auxiliary signals. Benefiting from the position-optimized quad-camera system, stereo phase unwrapping can be efficiently and reliably performed by flexible phase consistency checks. Besides, redundant information of multiple phase consistency checks is fully used through a weighted phase difference scheme to further enhance the reliability of phase unwrapping. This paper explains the 3D measurement principle and the basic design of quad-camera system, and finally demonstrates that in a large measurement volume of 200 mm × 200 mm × 400 mm, the resultant dynamic 3D sensing system can realize real-time 3D reconstruction at 60 frames per second with a depth precision of 50 μm.

[The modern approaches to the restoration of postural balance in the patients suffering from the consequences of an acute cerebrovascular accident (CVA)].

PubMed

Volovets, S A; Sergeenko, E Y; Darinskaya, L Y; Polyaev, B A; Yashinina, Y A; Isaeva, M A; Zhitareva, I V; Lobov, A N; Panova, T I

2018-05-21

the most frequent and severe consequences of an acute cerebrovascular accident (CVA) are locomotor and coordination disorders which significantly increase the risk of falling in a static position and when walking. The methods used for the rehabilitation of the affected patients are designed in the first place to enable the patients to acquire the skills necessary for maintaining the static balance. The modern equipment allows to carry out coordination training in the static position and also during walking. The objective of the present study was to evaluate, based on the results of our original research, the feasibility and effectiveness of the application of the «Balance tutor» system developed for the restoration of static and dynamic balance in the framework of the combined rehabilitation treatment of the patients suffering from impaired postural balance as a consequence of acute cerebrovascular accident (CVA). A total of 56 patients presenting with impaired postural balance following CVA were available for the examination. All of them underwent functional testing to assess the static and dynamic balance, walking abilities, and the risk of falling down including the study with the use of computer-assisted stabilometry. The study has demonstrated that the inclusion of the «Balance tutor» system for the restoration of the static and dynamic balance in the combined rehabilitative treatment of the patients having postural balance disorders after the CVA reduces the risk of fall for a walking patient, improves his (her) static and dynamic balance, increases the patient's ability to move without exterior help. The patients comprising the main study group were found to experience a decrease of statokinesiogram space in the «eyes are open» position (p = 0.0576, the Mann-Whitney U test) as well as a reliable decrease of the statokinesiogram space in the «eyes are closed» position (p=0.0063, the Mann-Whitney U test). Similar changes occurred in speed of pressure center relocation. By the end of the rehabilitation course, the patients of the main group exhibited a reliable enhancement in the dynamic balance rates estimated with the use of the Berg Balance Scale (p=0.028, Tukey's criterion), an increase in stability based at the Tinneti scale, p=0.0291; Tukey's criterion), and a decrease of the risk of falling during walk assessed with the application of Dynamic Gait Index scale (p = 0.0001, Tukey's criterion). The results of the present study with the inclusion of the «Balance tutor» system in the program of combined rehabilitation of the patients suffering from the consequences of CVA in the form of the postural balance impairment give evidence of the feasibility and effectiveness of this approach. There is reason to believe that its application is likely to reduce the risk of falling down and to improve characteristics of static and dynamic balance. The inclusion of the «Balance tutor» system in the program of combined rehabilitation of the patients suffering from the consequences of CVA in the form of the postural balance impairment is both feasible and effective.

A Hybrid Smartphone Indoor Positioning Solution for Mobile LBS

PubMed Central

Liu, Jingbin; Chen, Ruizhi; Pei, Ling; Guinness, Robert; Kuusniemi, Heidi

2012-01-01

Smartphone positioning is an enabling technology used to create new business in the navigation and mobile location-based services (LBS) industries. This paper presents a smartphone indoor positioning engine named HIPE that can be easily integrated with mobile LBS. HIPE is a hybrid solution that fuses measurements of smartphone sensors with wireless signals. The smartphone sensors are used to measure the user’s motion dynamics information (MDI), which represent the spatial correlation of various locations. Two algorithms based on hidden Markov model (HMM) problems, the grid-based filter and the Viterbi algorithm, are used in this paper as the central processor for data fusion to resolve the position estimates, and these algorithms are applicable for different applications, e.g., real-time navigation and location tracking, respectively. HIPE is more widely applicable for various motion scenarios than solutions proposed in previous studies because it uses no deterministic motion models, which have been commonly used in previous works. The experimental results showed that HIPE can provide adequate positioning accuracy and robustness for different scenarios of MDI combinations. HIPE is a cost-efficient solution, and it can work flexibly with different smartphone platforms, which may have different types of sensors available for the measurement of MDI data. The reliability of the positioning solution was found to increase with increasing precision of the MDI data. PMID:23235455

Distributed collaborative response surface method for mechanical dynamic assembly reliability design

NASA Astrophysics Data System (ADS)

Bai, Guangchen; Fei, Chengwei

2013-11-01

Because of the randomness of many impact factors influencing the dynamic assembly relationship of complex machinery, the reliability analysis of dynamic assembly relationship needs to be accomplished considering the randomness from a probabilistic perspective. To improve the accuracy and efficiency of dynamic assembly relationship reliability analysis, the mechanical dynamic assembly reliability(MDAR) theory and a distributed collaborative response surface method(DCRSM) are proposed. The mathematic model of DCRSM is established based on the quadratic response surface function, and verified by the assembly relationship reliability analysis of aeroengine high pressure turbine(HPT) blade-tip radial running clearance(BTRRC). Through the comparison of the DCRSM, traditional response surface method(RSM) and Monte Carlo Method(MCM), the results show that the DCRSM is not able to accomplish the computational task which is impossible for the other methods when the number of simulation is more than 100 000 times, but also the computational precision for the DCRSM is basically consistent with the MCM and improved by 0.40˜4.63% to the RSM, furthermore, the computational efficiency of DCRSM is up to about 188 times of the MCM and 55 times of the RSM under 10000 times simulations. The DCRSM is demonstrated to be a feasible and effective approach for markedly improving the computational efficiency and accuracy of MDAR analysis. Thus, the proposed research provides the promising theory and method for the MDAR design and optimization, and opens a novel research direction of probabilistic analysis for developing the high-performance and high-reliability of aeroengine.

Reliability and Validity of Gaze-Dependent Functional Vision Space: A Novel Metric Quantifying Visual Function in Infantile Nystagmus Syndrome.

PubMed

Roberts, Tawna L; Kester, Kristi N; Hertle, Richard W

2018-04-01

This study presents test-retest reliability of optotype visual acuity (OVA) across 60° of horizontal gaze position in patients with infantile nystagmus syndrome (INS). Also, the validity of the metric gaze-dependent functional vision space (GDFVS) is shown in patients with INS. In experiment 1, OVA was measured twice in seven horizontal gaze positions from 30° left to right in 10° steps in 20 subjects with INS and 14 without INS. Test-retest reliability was assessed using intraclass correlation coefficient (ICC) in each gaze. OVA area under the curve (AUC) was calculated with horizontal eye position on the x-axis, and logMAR visual acuity on the y-axis and then converted to GDFVS. In experiment 2, validity of GDFVS was determined over 40° horizontal gaze by applying the 95% limits of agreement from experiment 1 to pre- and post-treatment GDFVS values from 85 patients with INS. In experiment 1, test-retest reliability for OVA was high (ICC ≥ 0.88) as the difference in test-retest was on average less than 0.1 logMAR in each gaze position. In experiment 2, as a group, INS subjects had a significant increase (P < 0.001) in the size of their GDFVS that exceeded the 95% limits of agreement found during test-retest. OVA is a reliable measure in INS patients across 60° of horizontal gaze position. GDFVS is a valid clinical method to be used to quantify OVA as a function of eye position in INS patients. This method captures the dynamic nature of OVA in INS patients and may be a valuable measure to quantify visual function patients with INS, particularly in quantifying change as part of clinical studies.

THE DYNAMIC LEAP AND BALANCE TEST (DLBT): A TEST-RETEST RELIABILITY STUDY

PubMed Central

Newman, Thomas M.; Smith, Brent I.; John Miller, Sayers

2017-01-01

Background There is a need for new clinical assessment tools to test dynamic balance during typical functional movements. Common methods for assessing dynamic balance, such as the Star Excursion Balance Test, which requires controlled movement of body segments over an unchanged base of support, may not be an adequate measure for testing typical functional movements that involve controlled movement of body segments along with a change in base of support. Purpose/hypothesis The purpose of this study was to determine the reliability of the Dynamic Leap and Balance Test (DLBT) by assessing its test-retest reliability. It was hypothesized that there would be no statistically significant differences between testing days in time taken to complete the test. Study Design Reliability study Methods Thirty healthy college aged individuals participated in this study. Participants performed a series of leaps in a prescribed sequence, unique to the DLBT test. Time required by the participants to complete the 20-leap task was the dependent variable. Subjects leaped back and forth from peripheral to central targets alternating weight bearing from one leg to the other. Participants landed on the central target with the tested limb and were required to stabilize for two seconds before leaping to the next target. Stability was based upon qualitative measures similar to Balance Error Scoring System. Each assessment was comprised of three trials and performed on two days with a separation of at least six days. Results Two-way mixed ANOVA was used to analyze the differences in time to complete the sequence between the three trial averages of the two testing sessions. Intraclass Correlation Coefficient (ICC3,1) was used to establish between session test-retest reliability of the test trial averages. Significance was set a priori at p ≤ 0.05. No significant differences (p > 0.05) were detected between the two testing sessions. The ICC was 0.93 with a 95% confidence interval from 0.84 to 0.96. Conclusion This test is a cost-effective, easy to administer and clinically relevant novel measure for assessing dynamic balance that has excellent test-retest reliability. Clinical relevance As a new measure of dynamic balance, the DLBT has the potential to be a cost-effective, challenging and functional tool for clinicians. Level of Evidence 2b PMID:28900556

Real-Time Telemetry System for Monitoring Motion of Ships Based on Inertial Sensors.

PubMed

Núñez, José M; Araújo, Marta G; García-Tuñón, I

2017-04-25

A telemetry system for real-time monitoring of the motions, position, speed and course of a ship at sea is presented in this work. The system, conceived as a subsystem of a radar cross-section measurement unit, could also be used in other applications as ships dynamics characterization, on-board cranes, antenna stabilizers, etc. This system was designed to be stand-alone, reliable, easy to deploy, low-cost and free of requirements related to stabilization procedures. In order to achieve such a unique combination of functionalities, we have developed a telemetry system based on redundant inertial and magnetic sensors and GPS (Global Positioning System) measurements. It provides a proper data storage and also has real-time radio data transmission capabilities to an on-shore station. The output of the system can be used either for on-line or off-line processing. Additionally, the system uses dual technologies and COTS (Commercial Off-The-Shelf) components. Motion-positioning measurements and radio data link tests were successfully carried out in several ships of the Spanish Navy, proving the compliance with the design targets and validating our telemetry system.

A reliability analysis of the revised competitiveness index.

PubMed

Harris, Paul B; Houston, John M

2010-06-01

This study examined the reliability of the Revised Competitiveness Index by investigating the test-retest reliability, interitem reliability, and factor structure of the measure based on a sample of 280 undergraduates (200 women, 80 men) ranging in age from 18 to 28 years (M = 20.1, SD = 2.1). The findings indicate that the Revised Competitiveness Index has high test-retest reliability, high inter-item reliability, and a stable factor structure. The results support the assertion that the Revised Competitiveness Index assesses competitiveness as a stable trait rather than a dynamic state.

Modeling Sensor Reliability in Fault Diagnosis Based on Evidence Theory

PubMed Central

Yuan, Kaijuan; Xiao, Fuyuan; Fei, Liguo; Kang, Bingyi; Deng, Yong

2016-01-01

Sensor data fusion plays an important role in fault diagnosis. Dempster–Shafer (D-R) evidence theory is widely used in fault diagnosis, since it is efficient to combine evidence from different sensors. However, under the situation where the evidence highly conflicts, it may obtain a counterintuitive result. To address the issue, a new method is proposed in this paper. Not only the statistic sensor reliability, but also the dynamic sensor reliability are taken into consideration. The evidence distance function and the belief entropy are combined to obtain the dynamic reliability of each sensor report. A weighted averaging method is adopted to modify the conflict evidence by assigning different weights to evidence according to sensor reliability. The proposed method has better performance in conflict management and fault diagnosis due to the fact that the information volume of each sensor report is taken into consideration. An application in fault diagnosis based on sensor fusion is illustrated to show the efficiency of the proposed method. The results show that the proposed method improves the accuracy of fault diagnosis from 81.19% to 89.48% compared to the existing methods. PMID:26797611

Development and Validation of the Primary Care Team Dynamics Survey

PubMed Central

Song, Hummy; Chien, Alyna T; Fisher, Josephine; Martin, Julia; Peters, Antoinette S; Hacker, Karen; Rosenthal, Meredith B; Singer, Sara J

2015-01-01

Objective To develop and validate a survey instrument designed to measure team dynamics in primary care. Data Sources/Study Setting We studied 1,080 physician and nonphysician health care professionals working at 18 primary care practices participating in a learning collaborative aimed at improving team-based care. Study Design We developed a conceptual model and administered a cross-sectional survey addressing team dynamics, and we assessed reliability and discriminant validity of survey factors and the overall survey's goodness-of-fit using structural equation modeling. Data Collection We administered the survey between September 2012 and March 2013. Principal Findings Overall response rate was 68 percent (732 respondents). Results support a seven-factor model of team dynamics, suggesting that conditions for team effectiveness, shared understanding, and three supportive processes are associated with acting and feeling like a team and, in turn, perceived team effectiveness. This model demonstrated adequate fit (goodness-of-fit index: 0.91), scale reliability (Cronbach's alphas: 0.71–0.91), and discriminant validity (average factor correlations: 0.49). Conclusions It is possible to measure primary care team dynamics reliably using a 29-item survey. This survey may be used in ambulatory settings to study teamwork and explore the effect of efforts to improve team-based care. Future studies should demonstrate the importance of team dynamics for markers of team effectiveness (e.g., work satisfaction, care quality, clinical outcomes). PMID:25423886

Development and validation of the primary care team dynamics survey.

PubMed

Song, Hummy; Chien, Alyna T; Fisher, Josephine; Martin, Julia; Peters, Antoinette S; Hacker, Karen; Rosenthal, Meredith B; Singer, Sara J

2015-06-01

To develop and validate a survey instrument designed to measure team dynamics in primary care. We studied 1,080 physician and nonphysician health care professionals working at 18 primary care practices participating in a learning collaborative aimed at improving team-based care. We developed a conceptual model and administered a cross-sectional survey addressing team dynamics, and we assessed reliability and discriminant validity of survey factors and the overall survey's goodness-of-fit using structural equation modeling. We administered the survey between September 2012 and March 2013. Overall response rate was 68 percent (732 respondents). Results support a seven-factor model of team dynamics, suggesting that conditions for team effectiveness, shared understanding, and three supportive processes are associated with acting and feeling like a team and, in turn, perceived team effectiveness. This model demonstrated adequate fit (goodness-of-fit index: 0.91), scale reliability (Cronbach's alphas: 0.71-0.91), and discriminant validity (average factor correlations: 0.49). It is possible to measure primary care team dynamics reliably using a 29-item survey. This survey may be used in ambulatory settings to study teamwork and explore the effect of efforts to improve team-based care. Future studies should demonstrate the importance of team dynamics for markers of team effectiveness (e.g., work satisfaction, care quality, clinical outcomes). © Health Research and Educational Trust.

Modeling Nonstationary Emotion Dynamics in Dyads using a Time-Varying Vector-Autoregressive Model.

PubMed

Bringmann, Laura F; Ferrer, Emilio; Hamaker, Ellen L; Borsboom, Denny; Tuerlinckx, Francis

2018-01-01

Emotion dynamics are likely to arise in an interpersonal context. Standard methods to study emotions in interpersonal interaction are limited because stationarity is assumed. This means that the dynamics, for example, time-lagged relations, are invariant across time periods. However, this is generally an unrealistic assumption. Whether caused by an external (e.g., divorce) or an internal (e.g., rumination) event, emotion dynamics are prone to change. The semi-parametric time-varying vector-autoregressive (TV-VAR) model is based on well-studied generalized additive models, implemented in the software R. The TV-VAR can explicitly model changes in temporal dependency without pre-existing knowledge about the nature of change. A simulation study is presented, showing that the TV-VAR model is superior to the standard time-invariant VAR model when the dynamics change over time. The TV-VAR model is applied to empirical data on daily feelings of positive affect (PA) from a single couple. Our analyses indicate reliable changes in the male's emotion dynamics over time, but not in the female's-which were not predicted by her own affect or that of her partner. This application illustrates the usefulness of using a TV-VAR model to detect changes in the dynamics in a system.

A Research Roadmap for Computation-Based Human Reliability Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boring, Ronald; Mandelli, Diego; Joe, Jeffrey

2015-08-01

The United States (U.S.) Department of Energy (DOE) is sponsoring research through the Light Water Reactor Sustainability (LWRS) program to extend the life of the currently operating fleet of commercial nuclear power plants. The Risk Informed Safety Margin Characterization (RISMC) research pathway within LWRS looks at ways to maintain and improve the safety margins of these plants. The RISMC pathway includes significant developments in the area of thermalhydraulics code modeling and the development of tools to facilitate dynamic probabilistic risk assessment (PRA). PRA is primarily concerned with the risk of hardware systems at the plant; yet, hardware reliability is oftenmore » secondary in overall risk significance to human errors that can trigger or compound undesirable events at the plant. This report highlights ongoing efforts to develop a computation-based approach to human reliability analysis (HRA). This computation-based approach differs from existing static and dynamic HRA approaches in that it: (i) interfaces with a dynamic computation engine that includes a full scope plant model, and (ii) interfaces with a PRA software toolset. The computation-based HRA approach presented in this report is called the Human Unimodels for Nuclear Technology to Enhance Reliability (HUNTER) and incorporates in a hybrid fashion elements of existing HRA methods to interface with new computational tools developed under the RISMC pathway. The goal of this research effort is to model human performance more accurately than existing approaches, thereby minimizing modeling uncertainty found in current plant risk models.« less

Complementary Reliability-Based Decodings of Binary Linear Block Codes

NASA Technical Reports Server (NTRS)

Fossorier, Marc P. C.; Lin, Shu

1997-01-01

This correspondence presents a hybrid reliability-based decoding algorithm which combines the reprocessing method based on the most reliable basis and a generalized Chase-type algebraic decoder based on the least reliable positions. It is shown that reprocessing with a simple additional algebraic decoding effort achieves significant coding gain. For long codes, the order of reprocessing required to achieve asymptotic optimum error performance is reduced by approximately 1/3. This significantly reduces the computational complexity, especially for long codes. Also, a more efficient criterion for stopping the decoding process is derived based on the knowledge of the algebraic decoding solution.

Generic Dynamic Environment Perception Using Smart Mobile Devices.

PubMed

Danescu, Radu; Itu, Razvan; Petrovai, Andra

2016-10-17

The driving environment is complex and dynamic, and the attention of the driver is continuously challenged, therefore computer based assistance achieved by processing image and sensor data may increase traffic safety. While active sensors and stereovision have the advantage of obtaining 3D data directly, monocular vision is easy to set up, and can benefit from the increasing computational power of smart mobile devices, and from the fact that almost all of them come with an embedded camera. Several driving assistance application are available for mobile devices, but they are mostly targeted for simple scenarios and a limited range of obstacle shapes and poses. This paper presents a technique for generic, shape independent real-time obstacle detection for mobile devices, based on a dynamic, free form 3D representation of the environment: the particle based occupancy grid. Images acquired in real time from the smart mobile device's camera are processed by removing the perspective effect and segmenting the resulted bird-eye view image to identify candidate obstacle areas, which are then used to update the occupancy grid. The occupancy grid tracked cells are grouped into obstacles depicted as cuboids having position, size, orientation and speed. The easy to set up system is able to reliably detect most obstacles in urban traffic, and its measurement accuracy is comparable to a stereovision system.

Simulating the dynamic behavior of a vertical axis wind turbine operating in unsteady conditions

NASA Astrophysics Data System (ADS)

Battisti, L.; Benini, E.; Brighenti, A.; Soraperra, G.; Raciti Castelli, M.

2016-09-01

The present work aims at assessing the reliability of a simulation tool capable of computing the unsteady rotational motion and the associated tower oscillations of a variable speed VAWT immersed in a coherent turbulent wind. As a matter of fact, since the dynamic behaviour of a variable speed turbine strongly depends on unsteady wind conditions (wind gusts), a steady state approach can't accurately catch transient correlated issues. The simulation platform proposed here is implemented using a lumped mass approach: the drive train is described by resorting to both the polar inertia and the angular position of rotating parts, also considering their speed and acceleration, while rotor aerodynamic is based on steady experimental curves. The ultimate objective of the presented numerical platform is the simulation of transient phenomena, driven by turbulence, occurring during rotor operation, with the aim of supporting the implementation of efficient and robust control algorithms.

Experimental Evaluation of UWB Indoor Positioning for Sport Postures

PubMed Central

Defraye, Jense; Steendam, Heidi; Gerlo, Joeri; De Clercq, Dirk; De Poorter, Eli

2018-01-01

Radio frequency (RF)-based indoor positioning systems (IPSs) use wireless technologies (including Wi-Fi, Zigbee, Bluetooth, and ultra-wide band (UWB)) to estimate the location of persons in areas where no Global Positioning System (GPS) reception is available, for example in indoor stadiums or sports halls. Of the above-mentioned forms of radio frequency (RF) technology, UWB is considered one of the most accurate approaches because it can provide positioning estimates with centimeter-level accuracy. However, it is not yet known whether UWB can also offer such accurate position estimates during strenuous dynamic activities in which moves are characterized by fast changes in direction and velocity. To answer this question, this paper investigates the capabilities of UWB indoor localization systems for tracking athletes during their complex (and most of the time unpredictable) movements. To this end, we analyze the impact of on-body tag placement locations and human movement patterns on localization accuracy and communication reliability. Moreover, two localization algorithms (particle filter and Kalman filter) with different optimizations (bias removal, non-line-of-sight (NLoS) detection, and path determination) are implemented. It is shown that although the optimal choice of optimization depends on the type of movement patterns, some of the improvements can reduce the localization error by up to 31%. Overall, depending on the selected optimization and on-body tag placement, our algorithms show good results in terms of positioning accuracy, with average errors in position estimates of 20 cm. This makes UWB a suitable approach for tracking dynamic athletic activities. PMID:29315267

Reliability-based structural optimization: A proposed analytical-experimental study

NASA Technical Reports Server (NTRS)

Stroud, W. Jefferson; Nikolaidis, Efstratios

1993-01-01

An analytical and experimental study for assessing the potential of reliability-based structural optimization is proposed and described. In the study, competing designs obtained by deterministic and reliability-based optimization are compared. The experimental portion of the study is practical because the structure selected is a modular, actively and passively controlled truss that consists of many identical members, and because the competing designs are compared in terms of their dynamic performance and are not destroyed if failure occurs. The analytical portion of this study is illustrated on a 10-bar truss example. In the illustrative example, it is shown that reliability-based optimization can yield a design that is superior to an alternative design obtained by deterministic optimization. These analytical results provide motivation for the proposed study, which is underway.

Changes in J-SOAP-II and SAVRY Scores Over the Course of Residential, Cognitive-Behavioral Treatment for Adolescent Sexual Offending

PubMed Central

Viljoen, Jodi L.; Gray, Andrew L.; Shaffer, Catherine; Latzman, Natasha E.; Scalora, Mario J.; Ullman, Daniel

2018-01-01

Although the Juvenile Sex Offender Assessment Protocol–II (J-SOAP-II) and the Structured Assessment of Violence Risk in Youth (SAVRY) include an emphasis on dynamic, or modifiable factors, there has been little research on dynamic changes on these tools. To help address this gap, we compared admission and discharge scores of 163 adolescents who attended a residential, cognitive-behavioral treatment program for sexual offending. Based on reliable change indices, one half of youth showed a reliable decrease on the J-SOAP-II Dynamic Risk Total Score and one third of youth showed a reliable decrease on the SAVRY Dynamic Risk Total Score. Contrary to expectations, decreases in risk factors and increases in protective factors did not predict reduced sexual, violent nonsexual, or any reoffending. In addition, no associations were found between scores on the Psychopathy Checklist:Youth Version and levels of change. Overall, the J-SOAP-II and the SAVRY hold promise in measuring change, but further research is needed. PMID:26199271

Changes in J-SOAP-II and SAVRY Scores Over the Course of Residential, Cognitive-Behavioral Treatment for Adolescent Sexual Offending.

PubMed

Viljoen, Jodi L; Gray, Andrew L; Shaffer, Catherine; Latzman, Natasha E; Scalora, Mario J; Ullman, Daniel

2017-06-01

Although the Juvenile Sex Offender Assessment Protocol-II (J-SOAP-II) and the Structured Assessment of Violence Risk in Youth (SAVRY) include an emphasis on dynamic, or modifiable factors, there has been little research on dynamic changes on these tools. To help address this gap, we compared admission and discharge scores of 163 adolescents who attended a residential, cognitive-behavioral treatment program for sexual offending. Based on reliable change indices, one half of youth showed a reliable decrease on the J-SOAP-II Dynamic Risk Total Score and one third of youth showed a reliable decrease on the SAVRY Dynamic Risk Total Score. Contrary to expectations, decreases in risk factors and increases in protective factors did not predict reduced sexual, violent nonsexual, or any reoffending. In addition, no associations were found between scores on the Psychopathy Checklist:Youth Version and levels of change. Overall, the J-SOAP-II and the SAVRY hold promise in measuring change, but further research is needed.

Molecular Dynamics Simulations and Kinetic Measurements to Estimate and Predict Protein-Ligand Residence Times.

PubMed

Mollica, Luca; Theret, Isabelle; Antoine, Mathias; Perron-Sierra, Françoise; Charton, Yves; Fourquez, Jean-Marie; Wierzbicki, Michel; Boutin, Jean A; Ferry, Gilles; Decherchi, Sergio; Bottegoni, Giovanni; Ducrot, Pierre; Cavalli, Andrea

2016-08-11

Ligand-target residence time is emerging as a key drug discovery parameter because it can reliably predict drug efficacy in vivo. Experimental approaches to binding and unbinding kinetics are nowadays available, but we still lack reliable computational tools for predicting kinetics and residence time. Most attempts have been based on brute-force molecular dynamics (MD) simulations, which are CPU-demanding and not yet particularly accurate. We recently reported a new scaled-MD-based protocol, which showed potential for residence time prediction in drug discovery. Here, we further challenged our procedure's predictive ability by applying our methodology to a series of glucokinase activators that could be useful for treating type 2 diabetes mellitus. We combined scaled MD with experimental kinetics measurements and X-ray crystallography, promptly checking the protocol's reliability by directly comparing computational predictions and experimental measures. The good agreement highlights the potential of our scaled-MD-based approach as an innovative method for computationally estimating and predicting drug residence times.

Girsanov's transformation based variance reduced Monte Carlo simulation schemes for reliability estimation in nonlinear stochastic dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanjilal, Oindrila, E-mail: oindrila@civil.iisc.ernet.in; Manohar, C.S., E-mail: manohar@civil.iisc.ernet.in

The study considers the problem of simulation based time variant reliability analysis of nonlinear randomly excited dynamical systems. Attention is focused on importance sampling strategies based on the application of Girsanov's transformation method. Controls which minimize the distance function, as in the first order reliability method (FORM), are shown to minimize a bound on the sampling variance of the estimator for the probability of failure. Two schemes based on the application of calculus of variations for selecting control signals are proposed: the first obtains the control force as the solution of a two-point nonlinear boundary value problem, and, the secondmore » explores the application of the Volterra series in characterizing the controls. The relative merits of these schemes, vis-à-vis the method based on ideas from the FORM, are discussed. Illustrative examples, involving archetypal single degree of freedom (dof) nonlinear oscillators, and a multi-degree of freedom nonlinear dynamical system, are presented. The credentials of the proposed procedures are established by comparing the solutions with pertinent results from direct Monte Carlo simulations. - Highlights: • The distance minimizing control forces minimize a bound on the sampling variance. • Establishing Girsanov controls via solution of a two-point boundary value problem. • Girsanov controls via Volterra's series representation for the transfer functions.« less

Evaluation on real-time dynamic performance of BDS in PPP, RTK, and INS tightly aided modes

NASA Astrophysics Data System (ADS)

Gao, Zhouzheng; Li, Tuan; Zhang, Hongping; Ge, Maorong; Schuh, Harald

2018-05-01

Since China's BeiDou satellite navigation system (BDS) began to provide regional navigation service for Asia-Pacific region after 2012, more new generation BDS satellites have been launched to further expand BDS's coverage to be global. In this contribution, precise positioning models based on BDS and the corresponding mathematical algorithms are presented in detail. Then, an evaluation on BDS's real-time dynamic positioning and navigation performance is presented in Precise Point Positioning (PPP), Real-time Kinematic (RTK), Inertial Navigation System (INS) tightly aided PPP and RTK modes by processing a set of land-borne vehicle experiment data. Results indicate that BDS positioning Root Mean Square (RMS) in north, east, and vertical components are 2.0, 2.7, and 7.6 cm in RTK mode and 7.8, 14.7, and 24.8 cm in PPP mode, which are close to GPS positioning accuracy. Meanwhile, with the help of INS, about 38.8%, 67.5%, and 66.5% improvements can be obtained by using PPP/INS tight-integration mode. Such enhancements in RTK/INS tight-integration mode are 14.1%, 34.0%, and 41.9%. Moreover, the accuracy of velocimetry and attitude determination can be improved to be better than 1 cm/s and 0.1°, respectively. Besides, the continuity and reliability of BDS in both PPP and RTK modes can also be ameliorated significantly by INS during satellite signal missing periods.

The long-term reliability of static and dynamic quantitative sensory testing in healthy individuals.

PubMed

Marcuzzi, Anna; Wrigley, Paul J; Dean, Catherine M; Adams, Roger; Hush, Julia M

2017-07-01

Quantitative sensory tests (QSTs) have been increasingly used to investigate alterations in somatosensory function in a wide range of painful conditions. The interpretation of these findings is based on the assumption that the measures are stable and reproducible. To date, reliability of QST has been investigated for short test-retest intervals. The aim of this study was to investigate the long-term reliability of a multimodal QST assessment in healthy people, with testing conducted on 3 occasions over 4 months. Forty-two healthy people were enrolled in the study. Static and dynamic tests were performed, including cold and heat pain threshold (CPT, HPT), mechanical wind-up [wind-up ratio (WUR)], pressure pain threshold (PPT), 2-point discrimination (TPD), and conditioned pain modulation (CPM). Systematic bias, relative reliability and agreement were analysed using repeated measure analysis of variance, intraclass correlation coefficients (ICCs3,1) and SE of the measurement (SEM), respectively. Static QST (CPT, HPT, PPT, and TPD) showed good-to-excellent reliability (ICCs: 0.68-0.90). Dynamic QST (WUR and CPM) showed poor-to-good reliability (ICCs: 0.35-0.61). A significant linear decrease over time was observed for mechanical QST at the back (PPT and TPD) and for CPM (P < 0.01). Static QST were stable over a period of 4 months; however, a small systematic decrease over time has been observed for mechanical QST. Dynamic QST showed considerable variability over time; in particular, CPM using PPT as the test stimulus did not show adequate reliability, suggesting that this test paradigm may be less useful for monitoring individuals over time.

Subtitles and Eye Tracking: Reading and Performance

ERIC Educational Resources Information Center

Kruger, Jan-Louis; Steyn, Faans

2014-01-01

This article presents an experimental study to investigate whether subtitle reading has a positive impact on academic performance. In the absence of reliable indexes of reading behavior in dynamic texts, the article first formulates and validates an index to measure the reading of text, such as subtitles on film. Eye-tracking measures (fixations…

Induced transducer orientation during ultrasound imaging: effects on abdominal muscle thickness and bladder position.

PubMed

Whittaker, Jackie L; Warner, Martin B; Stokes, Maria J

2009-11-01

The use of ultrasound imaging (USI) by physiotherapists to assess muscle behavior in clinical settings is increasing. However, there is relatively little evidence of whether the clinical environment is conducive to valid and reliable measurements. Accurate USI measurements depend on maintaining a relatively stationary transducer position, because motion may distort the image and lead to erroneous conclusions. This would seem particularly important during dynamic studies typical of a physiotherapy assessment. What is not known is how much transducer motion can occur before error is introduced. The aim of this study is to shed some light on this question. Eight healthy volunteers (19 to 52 y) participated. USI images were taken of the lateral abdominal wall (LAW) and bladder base (midline suprapubic) at various manually induced transducer orientations (approximately -10 to 10 degrees about 3 axes of rotation), which were quantified by a digital optical motion capture system. Measurements of transversus abdominis (TrA) thickness and bladder base position (cranial /caudal and anterior/posterior) were calculated. Repeated measures analysis of variance was performed to determine if the measurements obtained at the induced transducer orientations were statistically different (p<0.05) from an image corresponding to a reference or starting transducer orientation. Motion analysis data corresponding to measurements that did not differ from reference image measurements were summarized to provide a range of acceptable transducer motion (relative to the pelvis) for clockwise (CW)/counter-clockwise (CCW) rotation, cranial/caudal tilting, medial/lateral tilting and inward/outward displacement. There were no significant changes in TrA thickness measurements if CW/CCW transducer motion was <9 degrees and cranial/caudal or medial/lateral transducer tilting was <5 degrees . Further, there were no significant changes in measurements of bladder base position if CW/CCW transducer motion was <10 degrees , cranial/caudal or medial/lateral transducer tilting was <10 degrees and 8 degrees , respectively and inward/outward motion was <8 mm. These findings provide guidance on acceptable amounts of transducer motion relative to the pelvis when generating measurements of TrA thickness and bladder base position. Future sonographic studies and clinical assessment investigating these parameters could take these findings into account to improve imaging technique reliability.

Reliability and validity of a tool to measure the severity of tongue thrust in children: the Tongue Thrust Rating Scale.

PubMed

Serel Arslan, S; Demir, N; Karaduman, A A

2017-02-01

This study aimed to develop a scale called Tongue Thrust Rating Scale (TTRS), which categorised tongue thrust in children in terms of its severity during swallowing, and to investigate its validity and reliability. The study describes the developmental phase of the TTRS and presented its content and criterion-based validity and interobserver and intra-observer reliability. For content validation, seven experts assessed the steps in the scale over two Delphi rounds. Two physical therapists evaluated videos of 50 children with cerebral palsy (mean age, 57·9 ± 16·8 months), using the TTRS to test criterion-based validity, interobserver and intra-observer reliability. The Karaduman Chewing Performance Scale (KCPS) and Drooling Severity and Frequency Scale (DSFS) were used for criterion-based validity. All the TTRS steps were deemed necessary. The content validity index was 0·857. A very strong positive correlation was found between two examinations by one physical therapist, which indicated intra-observer reliability (r = 0·938, P < 0·001). A very strong positive correlation was also found between the TTRS scores of two physical therapists, indicating interobserver reliability (r = 0·892, P < 0·001). There was also a strong positive correlation between the TTRS and KCPS (r = 0·724, P < 0·001) and a very strong positive correlation between the TTRS scores and DSFS (r = 0·822 and r = 0·755; P < 0·001). These results demonstrated the criterion-based validity of the TTRS. The TTRS is a valid, reliable and clinically easy-to-use functional instrument to document the severity of tongue thrust in children. © 2016 John Wiley & Sons Ltd.

A Foreign Object Damage Event Detector Data Fusion System for Turbofan Engines

NASA Technical Reports Server (NTRS)

Turso, James A.; Litt, Jonathan S.

2004-01-01

A Data Fusion System designed to provide a reliable assessment of the occurrence of Foreign Object Damage (FOD) in a turbofan engine is presented. The FOD-event feature level fusion scheme combines knowledge of shifts in engine gas path performance obtained using a Kalman filter, with bearing accelerometer signal features extracted via wavelet analysis, to positively identify a FOD event. A fuzzy inference system provides basic probability assignments (bpa) based on features extracted from the gas path analysis and bearing accelerometers to a fusion algorithm based on the Dempster-Shafer-Yager Theory of Evidence. Details are provided on the wavelet transforms used to extract the foreign object strike features from the noisy data and on the Kalman filter-based gas path analysis. The system is demonstrated using a turbofan engine combined-effects model (CEM), providing both gas path and rotor dynamic structural response, and is suitable for rapid-prototyping of control and diagnostic systems. The fusion of the disparate data can provide significantly more reliable detection of a FOD event than the use of either method alone. The use of fuzzy inference techniques combined with Dempster-Shafer-Yager Theory of Evidence provides a theoretical justification for drawing conclusions based on imprecise or incomplete data.

Design and Parametric Study of the Magnetic Sensor for Position Detection in Linear Motor Based on Nonlinear Parametric Model Order Reduction

PubMed Central

Paul, Sarbajit; Chang, Junghwan

2017-01-01

This paper presents a design approach for a magnetic sensor module to detect mover position using the proper orthogonal decomposition-dynamic mode decomposition (POD-DMD)-based nonlinear parametric model order reduction (PMOR). The parameterization of the sensor module is achieved by using the multipolar moment matching method. Several geometric variables of the sensor module are considered while developing the parametric study. The operation of the sensor module is based on the principle of the airgap flux density distribution detection by the Hall Effect IC. Therefore, the design objective is to achieve a peak flux density (PFD) greater than 0.1 T and total harmonic distortion (THD) less than 3%. To fulfill the constraint conditions, the specifications for the sensor module is achieved by using POD-DMD based reduced model. The POD-DMD based reduced model provides a platform to analyze the high number of design models very fast, with less computational burden. Finally, with the final specifications, the experimental prototype is designed and tested. Two different modes, 90° and 120° modes respectively are used to obtain the position information of the linear motor mover. The position information thus obtained are compared with that of the linear scale data, used as a reference signal. The position information obtained using the 120° mode has a standard deviation of 0.10 mm from the reference linear scale signal, whereas the 90° mode position signal shows a deviation of 0.23 mm from the reference. The deviation in the output arises due to the mechanical tolerances introduced into the specification during the manufacturing process. This provides a scope for coupling the reliability based design optimization in the design process as a future extension. PMID:28671580

Design and Parametric Study of the Magnetic Sensor for Position Detection in Linear Motor Based on Nonlinear Parametric model order reduction.

PubMed

Paul, Sarbajit; Chang, Junghwan

2017-07-01

This paper presents a design approach for a magnetic sensor module to detect mover position using the proper orthogonal decomposition-dynamic mode decomposition (POD-DMD)-based nonlinear parametric model order reduction (PMOR). The parameterization of the sensor module is achieved by using the multipolar moment matching method. Several geometric variables of the sensor module are considered while developing the parametric study. The operation of the sensor module is based on the principle of the airgap flux density distribution detection by the Hall Effect IC. Therefore, the design objective is to achieve a peak flux density (PFD) greater than 0.1 T and total harmonic distortion (THD) less than 3%. To fulfill the constraint conditions, the specifications for the sensor module is achieved by using POD-DMD based reduced model. The POD-DMD based reduced model provides a platform to analyze the high number of design models very fast, with less computational burden. Finally, with the final specifications, the experimental prototype is designed and tested. Two different modes, 90° and 120° modes respectively are used to obtain the position information of the linear motor mover. The position information thus obtained are compared with that of the linear scale data, used as a reference signal. The position information obtained using the 120° mode has a standard deviation of 0.10 mm from the reference linear scale signal, whereas the 90° mode position signal shows a deviation of 0.23 mm from the reference. The deviation in the output arises due to the mechanical tolerances introduced into the specification during the manufacturing process. This provides a scope for coupling the reliability based design optimization in the design process as a future extension.

Study of Bulk and Elementary Screw Dislocation Assisted Reverse Breakdown in Low-Voltage (< 250 V) 4H-SiC p(sup +)n Junction Diodes--Part II: Dynamic Breakdown Properties. Part 2; Dynamic Breakdown Properties

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.; Fazi, Christian

1999-01-01

This paper outlines the dynamic reverse-breakdown characteristics of low-voltage (<250 V) small-area <5 x 10(exp -4) sq cm 4H-SiC p(sup +)n diodes subjected to nonadiabatic breakdown-bias pulsewidths ranging from 0.1 to 20 microseconds. 4H-SiC diodes with and without elementary screw dislocations exhibited positive temperature coefficient of breakdown voltage and high junction failure power densities approximately five times larger than the average failure power density of reliable silicon pn rectifiers. This result indicates that highly reliable low-voltage SiC rectifiers may be attainable despite the presence of elementary screw dislocations. However, the impact of elementary screw dislocations on other more useful 4H-SiC power device structures, such as high-voltage (>1 kV) pn junction and Schottky rectifiers, and bipolar gain devices (thyristors, IGBT's, etc.) remains to be investigated.

Reliability optimization design of the gear modification coefficient based on the meshing stiffness

NASA Astrophysics Data System (ADS)

Wang, Qianqian; Wang, Hui

2018-04-01

Since the time varying meshing stiffness of gear system is the key factor affecting gear vibration, it is important to design the meshing stiffness to reduce vibration. Based on the effect of gear modification coefficient on the meshing stiffness, considering the random parameters, reliability optimization design of the gear modification is researched. The dimension reduction and point estimation method is used to estimate the moment of the limit state function, and the reliability is obtained by the forth moment method. The cooperation of the dynamic amplitude results before and after optimization indicates that the research is useful for the reduction of vibration and noise and the improvement of the reliability.

Requirements for efficient cell-type proportioning: regulatory timescales, stochasticity and lateral inhibition

NASA Astrophysics Data System (ADS)

Pfeuty, B.; Kaneko, K.

2016-04-01

The proper functioning of multicellular organisms requires the robust establishment of precise proportions between distinct cell types. This developmental differentiation process typically involves intracellular regulatory and stochastic mechanisms to generate cell-fate diversity as well as intercellular signaling mechanisms to coordinate cell-fate decisions at tissue level. We thus surmise that key insights about the developmental regulation of cell-type proportion can be captured by the modeling study of clustering dynamics in population of inhibitory-coupled noisy bistable systems. This general class of dynamical system is shown to exhibit a very stable two-cluster state, but also metastability, collective oscillations or noise-induced state hopping, which can prevent from timely and reliably reaching a robust and well-proportioned clustered state. To circumvent these obstacles or to avoid fine-tuning, we highlight a general strategy based on dual-time positive feedback loops, such as mediated through transcriptional versus epigenetic mechanisms, which improves proportion regulation by coordinating early and flexible lineage priming with late and firm commitment. This result sheds new light on the respective and cooperative roles of multiple regulatory feedback, stochasticity and lateral inhibition in developmental dynamics.

Reliability-based trajectory optimization using nonintrusive polynomial chaos for Mars entry mission

NASA Astrophysics Data System (ADS)

Huang, Yuechen; Li, Haiyang

2018-06-01

This paper presents the reliability-based sequential optimization (RBSO) method to settle the trajectory optimization problem with parametric uncertainties in entry dynamics for Mars entry mission. First, the deterministic entry trajectory optimization model is reviewed, and then the reliability-based optimization model is formulated. In addition, the modified sequential optimization method, in which the nonintrusive polynomial chaos expansion (PCE) method and the most probable point (MPP) searching method are employed, is proposed to solve the reliability-based optimization problem efficiently. The nonintrusive PCE method contributes to the transformation between the stochastic optimization (SO) and the deterministic optimization (DO) and to the approximation of trajectory solution efficiently. The MPP method, which is used for assessing the reliability of constraints satisfaction only up to the necessary level, is employed to further improve the computational efficiency. The cycle including SO, reliability assessment and constraints update is repeated in the RBSO until the reliability requirements of constraints satisfaction are satisfied. Finally, the RBSO is compared with the traditional DO and the traditional sequential optimization based on Monte Carlo (MC) simulation in a specific Mars entry mission to demonstrate the effectiveness and the efficiency of the proposed method.

Analysis of Food Hub Commerce and Participation Using Agent-Based Modeling: Integrating Financial and Social Drivers.

PubMed

Krejci, Caroline C; Stone, Richard T; Dorneich, Michael C; Gilbert, Stephen B

2016-02-01

Factors influencing long-term viability of an intermediated regional food supply network (food hub) were modeled using agent-based modeling techniques informed by interview data gathered from food hub participants. Previous analyses of food hub dynamics focused primarily on financial drivers rather than social factors and have not used mathematical models. Based on qualitative and quantitative data gathered from 22 customers and 11 vendors at a midwestern food hub, an agent-based model (ABM) was created with distinct consumer personas characterizing the range of consumer priorities. A comparison study determined if the ABM behaved differently than a model based on traditional economic assumptions. Further simulation studies assessed the effect of changes in parameters, such as producer reliability and the consumer profiles, on long-term food hub sustainability. The persona-based ABM model produced different and more resilient results than the more traditional way of modeling consumers. Reduced producer reliability significantly reduced trade; in some instances, a modest reduction in reliability threatened the sustainability of the system. Finally, a modest increase in price-driven consumers at the outset of the simulation quickly resulted in those consumers becoming a majority of the overall customer base. Results suggest that social factors, such as desire to support the community, can be more important than financial factors. An ABM of food hub dynamics, based on human factors data gathered from the field, can be a useful tool for policy decisions. Similar approaches can be used for modeling customer dynamics with other sustainable organizations. © 2015, Human Factors and Ergonomics Society.

Real-Time Telemetry System for Monitoring Motion of Ships Based on Inertial Sensors

PubMed Central

Núñez, José M.; Araújo, Marta G.; García-Tuñón, I.

2017-01-01

A telemetry system for real-time monitoring of the motions, position, speed and course of a ship at sea is presented in this work. The system, conceived as a subsystem of a radar cross-section measurement unit, could also be used in other applications as ships dynamics characterization, on-board cranes, antenna stabilizers, etc. This system was designed to be stand-alone, reliable, easy to deploy, low-cost and free of requirements related to stabilization procedures. In order to achieve such a unique combination of functionalities, we have developed a telemetry system based on redundant inertial and magnetic sensors and GPS (Global Positioning System) measurements. It provides a proper data storage and also has real-time radio data transmission capabilities to an on-shore station. The output of the system can be used either for on-line or off-line processing. Additionally, the system uses dual technologies and COTS (Commercial Off-The-Shelf) components. Motion-positioning measurements and radio data link tests were successfully carried out in several ships of the Spanish Navy, proving the compliance with the design targets and validating our telemetry system. PMID:28441330

North Atlantic Oscillation dynamics recorded in shells of a long-lived bivalve mollusk

NASA Astrophysics Data System (ADS)

Schöne, Bernd R.; Oschmann, Wolfgang; Rössler, Jochen; Freyre Castro, Antuané D.; Houk, Stephen D.; Kröncke, Ingrid; Dreyer, Wolfgang; Janssen, Ronald; Rumohr, Heye; Dunca, Elena

2003-12-01

Existing reconstructions of the winter North Atlantic Oscillation (WNAO) are based on terrestrial proxies and historical documents. No direct high-resolution, long-term rec ords from marine settings are available for this major climate-dictating phenomenon, which severely affects a variety of economic aspects of our society. Here we present a 245 yr proxy WNAO index based on shells of the long-lived marine bivalve mollusk Arctica islandica. Variations in annual rates of shell growth are positively correlated with WNAO-related changes in the food supply. Maximum amplitudes in frequency bands of 7 9 and 5 7 yr fall exactly within the range of instrumental and other proxy WNAO indices. These estimates were obtained for specimens collected live, 2000 km apart, in the central North Sea and on the Norwegian Shelf. Hence, the WNAO influences hydrographic regimes of large regions of the ocean. Our study demonstrates that A. islandica can reliably reconstruct WNAO dynamics for time intervals and regions without instrumental records. Our new tool functions as a proxy for the WNAO index prior to the twentieth-century greenhouse forcing and has the potential to further validate other proxy-based WNAO records.

Validity and reliability of smartphone magnetometer-based goniometer evaluation of shoulder abduction--A pilot study.

PubMed

Johnson, Linda B; Sumner, Sean; Duong, Tina; Yan, Posu; Bajcsy, Ruzena; Abresch, R Ted; de Bie, Evan; Han, Jay J

2015-12-01

Goniometers are commonly used by physical therapists to measure range-of-motion (ROM) in the musculoskeletal system. These measurements are used to assist in diagnosis and to help monitor treatment efficacy. With newly emerging technologies, smartphone-based applications are being explored for measuring joint angles and movement. This pilot study investigates the intra- and inter-rater reliability as well as concurrent validity of a newly-developed smartphone magnetometer-based goniometer (MG) application for measuring passive shoulder abduction in both sitting and supine positions, and compare against the traditional universal goniometer (UG). This is a comparative study with repeated measurement design. Three physical therapists utilized both the smartphone MG and a traditional UG to measure various angles of passive shoulder abduction in a healthy subject, whose shoulder was positioned in eight different positions with pre-determined degree of abduction while seated or supine. Each therapist was blinded to the measured angles. Concordance correlation coefficients (CCCs), Bland-Altman plotting methods, and Analysis of Variance (ANOVA) were used for statistical analyses. Both traditional UG and smartphone MG were reliable in repeated measures of standardized joint angle positions (average CCC > 0.997) with similar variability in both measurement tools (standard deviation (SD) ± 4°). Agreement between the UG and MG measurements was greater than 0.99 in all positions. Our results show that the smartphone MG has equivalent reliability compared to the traditional UG when measuring passive shoulder abduction ROM. With concordant measures and comparable reliability to the UG, the newly developed MG application shows potential as a useful tool to assess joint angles. Published by Elsevier Ltd.

Generic Dynamic Environment Perception Using Smart Mobile Devices

PubMed Central

Danescu, Radu; Itu, Razvan; Petrovai, Andra

2016-01-01

The driving environment is complex and dynamic, and the attention of the driver is continuously challenged, therefore computer based assistance achieved by processing image and sensor data may increase traffic safety. While active sensors and stereovision have the advantage of obtaining 3D data directly, monocular vision is easy to set up, and can benefit from the increasing computational power of smart mobile devices, and from the fact that almost all of them come with an embedded camera. Several driving assistance application are available for mobile devices, but they are mostly targeted for simple scenarios and a limited range of obstacle shapes and poses. This paper presents a technique for generic, shape independent real-time obstacle detection for mobile devices, based on a dynamic, free form 3D representation of the environment: the particle based occupancy grid. Images acquired in real time from the smart mobile device’s camera are processed by removing the perspective effect and segmenting the resulted bird-eye view image to identify candidate obstacle areas, which are then used to update the occupancy grid. The occupancy grid tracked cells are grouped into obstacles depicted as cuboids having position, size, orientation and speed. The easy to set up system is able to reliably detect most obstacles in urban traffic, and its measurement accuracy is comparable to a stereovision system. PMID:27763501

A new theory for X-ray diffraction.

PubMed

Fewster, Paul F

2014-05-01

This article proposes a new theory of X-ray scattering that has particular relevance to powder diffraction. The underlying concept of this theory is that the scattering from a crystal or crystallite is distributed throughout space: this leads to the effect that enhanced scatter can be observed at the `Bragg position' even if the `Bragg condition' is not satisfied. The scatter from a single crystal or crystallite, in any fixed orientation, has the fascinating property of contributing simultaneously to many `Bragg positions'. It also explains why diffraction peaks are obtained from samples with very few crystallites, which cannot be explained with the conventional theory. The intensity ratios for an Si powder sample are predicted with greater accuracy and the temperature factors are more realistic. Another consequence is that this new theory predicts a reliability in the intensity measurements which agrees much more closely with experimental observations compared to conventional theory that is based on `Bragg-type' scatter. The role of dynamical effects (extinction etc.) is discussed and how they are suppressed with diffuse scattering. An alternative explanation for the Lorentz factor is presented that is more general and based on the capture volume in diffraction space. This theory, when applied to the scattering from powders, will evaluate the full scattering profile, including peak widths and the `background'. The theory should provide an increased understanding of the reliability of powder diffraction measurements, and may also have wider implications for the analysis of powder diffraction data, by increasing the accuracy of intensities predicted from structural models.

Augmented reality-based electrode guidance system for reliable electroencephalography.

PubMed

Song, Chanho; Jeon, Sangseo; Lee, Seongpung; Ha, Ho-Gun; Kim, Jonghyun; Hong, Jaesung

2018-05-24

In longitudinal electroencephalography (EEG) studies, repeatable electrode positioning is essential for reliable EEG assessment. Conventional methods use anatomical landmarks as fiducial locations for the electrode placement. Since the landmarks are manually identified, the EEG assessment is inevitably unreliable because of individual variations among the subjects and the examiners. To overcome this unreliability, an augmented reality (AR) visualization-based electrode guidance system was proposed. The proposed electrode guidance system is based on AR visualization to replace the manual electrode positioning. After scanning and registration of the facial surface of a subject by an RGB-D camera, the AR of the initial electrode positions as reference positions is overlapped with the current electrode positions in real time. Thus, it can guide the position of the subsequently placed electrodes with high repeatability. The experimental results with the phantom show that the repeatability of the electrode positioning was improved compared to that of the conventional 10-20 positioning system. The proposed AR guidance system improves the electrode positioning performance with a cost-effective system, which uses only RGB-D camera. This system can be used as an alternative to the international 10-20 system.

Research on dynamic routing mechanisms in wireless sensor networks.

PubMed

Zhao, A Q; Weng, Y N; Lu, Y; Liu, C Y

2014-01-01

WirelessHART is the most widely applied standard in wireless sensor networks nowadays. However, it does not provide any dynamic routing mechanism, which is important for the reliability and robustness of the wireless network applications. In this paper, a collection tree protocol based, dynamic routing mechanism was proposed for WirelessHART network. The dynamic routing mechanism was evaluated through several simulation experiments in three aspects: time for generating the topology, link quality, and stability of network. Besides, the data transmission efficiency of this routing mechanism was analyzed. The simulation and evaluation results show that this mechanism can act as a dynamic routing mechanism for the TDMA-based wireless sensor network.

Small numbers, disclosure risk, security, and reliability issues in Web-based data query systems.

PubMed

Rudolph, Barbara A; Shah, Gulzar H; Love, Denise

2006-01-01

This article describes the process for developing consensus guidelines and tools for releasing public health data via the Web and highlights approaches leading agencies have taken to balance disclosure risk with public dissemination of reliable health statistics. An agency's choice of statistical methods for improving the reliability of released data for Web-based query systems is based upon a number of factors, including query system design (dynamic analysis vs preaggregated data and tables), population size, cell size, data use, and how data will be supplied to users. The article also describes those efforts that are necessary to reduce the risk of disclosure of an individual's protected health information.

Structural validity and reliability of the Positive and Negative Affect Schedule (PANAS): evidence from a large Brazilian community sample.

PubMed

Carvalho, Hudson W de; Andreoli, Sérgio B; Lara, Diogo R; Patrick, Christopher J; Quintana, Maria Inês; Bressan, Rodrigo A; Melo, Marcelo F de; Mari, Jair de J; Jorge, Miguel R

2013-01-01

Positive and negative affect are the two psychobiological-dispositional dimensions reflecting proneness to positive and negative activation that influence the extent to which individuals experience life events as joyful or as distressful. The Positive and Negative Affect Schedule (PANAS) is a structured questionnaire that provides independent indexes of positive and negative affect. This study aimed to validate a Brazilian interview-version of the PANAS by means of factor and internal consistency analysis. A representative community sample of 3,728 individuals residing in the cities of São Paulo and Rio de Janeiro, Brazil, voluntarily completed the PANAS. Exploratory structural equation model analysis was based on maximum likelihood estimation and reliability was calculated via Cronbach's alpha coefficient. Our results provide support for the hypothesis that the PANAS reliably measures two distinct dimensions of positive and negative affect. The structure and reliability of the Brazilian version of the PANAS are consistent with those of its original version. Taken together, these results attest the validity of the Brazilian adaptation of the instrument.

Modeling of human operator dynamics in simple manual control utilizing time series analysis. [tracking (position)

NASA Technical Reports Server (NTRS)

Agarwal, G. C.; Osafo-Charles, F.; Oneill, W. D.; Gottlieb, G. L.

1982-01-01

Time series analysis is applied to model human operator dynamics in pursuit and compensatory tracking modes. The normalized residual criterion is used as a one-step analytical tool to encompass the processes of identification, estimation, and diagnostic checking. A parameter constraining technique is introduced to develop more reliable models of human operator dynamics. The human operator is adequately modeled by a second order dynamic system both in pursuit and compensatory tracking modes. In comparing the data sampling rates, 100 msec between samples is adequate and is shown to provide better results than 200 msec sampling. The residual power spectrum and eigenvalue analysis show that the human operator is not a generator of periodic characteristics.

Reliability and Validity Assessment of a Linear Position Transducer

PubMed Central

Garnacho-Castaño, Manuel V.; López-Lastra, Silvia; Maté-Muñoz, José L.

2015-01-01

The objectives of the study were to determine the validity and reliability of peak velocity (PV), average velocity (AV), peak power (PP) and average power (AP) measurements were made using a linear position transducer. Validity was assessed by comparing measurements simultaneously obtained using the Tendo Weightlifting Analyzer Systemi and T-Force Dynamic Measurement Systemr (Ergotech, Murcia, Spain) during two resistance exercises, bench press (BP) and full back squat (BS), performed by 71 trained male subjects. For the reliability study, a further 32 men completed both lifts using the Tendo Weightlifting Analyzer Systemz in two identical testing sessions one week apart (session 1 vs. session 2). Intraclass correlation coefficients (ICCs) indicating the validity of the Tendo Weightlifting Analyzer Systemi were high, with values ranging from 0.853 to 0.989. Systematic biases and random errors were low to moderate for almost all variables, being higher in the case of PP (bias ±157.56 W; error ±131.84 W). Proportional biases were identified for almost all variables. Test-retest reliability was strong with ICCs ranging from 0.922 to 0.988. Reliability results also showed minimal systematic biases and random errors, which were only significant for PP (bias -19.19 W; error ±67.57 W). Only PV recorded in the BS showed no significant proportional bias. The Tendo Weightlifting Analyzer Systemi emerged as a reliable system for measuring movement velocity and estimating power in resistance exercises. The low biases and random errors observed here (mainly AV, AP) make this device a useful tool for monitoring resistance training. Key points This study determined the validity and reliability of peak velocity, average velocity, peak power and average power measurements made using a linear position transducer The Tendo Weight-lifting Analyzer Systemi emerged as a reliable system for measuring movement velocity and power. PMID:25729300

A fuzzy set approach for reliability calculation of valve controlling electric actuators

NASA Astrophysics Data System (ADS)

Karmachev, D. P.; Yefremov, A. A.; Luneva, E. E.

2017-02-01

The oil and gas equipment and electric actuators in particular frequently perform in various operational modes and under dynamic environmental conditions. These factors affect equipment reliability measures in a vague, uncertain way. To eliminate the ambiguity, reliability model parameters could be defined as fuzzy numbers. We suggest a technique that allows constructing fundamental fuzzy-valued performance reliability measures based on an analysis of electric actuators failure data in accordance with the amount of work, completed before the failure, instead of failure time. Also, this paper provides a computation example of fuzzy-valued reliability and hazard rate functions, assuming Kumaraswamy complementary Weibull geometric distribution as a lifetime (reliability) model for electric actuators.

Study on UKF based federal integrated navigation for high dynamic aviation

NASA Astrophysics Data System (ADS)

Zhao, Gang; Shao, Wei; Chen, Kai; Yan, Jie

2011-08-01

High dynamic aircraft is a very attractive new generation vehicles, in which provides near space aviation with large flight envelope both speed and altitude, for example the hypersonic vehicles. The complex flight environments for high dynamic vehicles require high accuracy and stability navigation scheme. Since the conventional Strapdown Inertial Navigation System (SINS) and Global Position System (GPS) federal integrated scheme based on EKF (Extended Kalman Filter) is invalidation in GPS single blackout situation because of high speed flight, a new high precision and stability integrated navigation approach is presented in this paper, in which the SINS, GPS and Celestial Navigation System (CNS) is combined as a federal information fusion configuration based on nonlinear Unscented Kalman Filter (UKF) algorithm. Firstly, the new integrated system state error is modeled. According to this error model, the SINS system is used as the navigation solution mathematic platform. The SINS combine with GPS constitute one error estimation filter subsystem based on UKF to obtain local optimal estimation, and the SINS combine with CNS constitute another error estimation subsystem. A non-reset federated configuration filter based on partial information is proposed to fuse two local optimal estimations to get global optimal error estimation, and the global optimal estimation is used to correct the SINS navigation solution. The χ 2 fault detection method is used to detect the subsystem fault, and the fault subsystem is isolation through fault interval to protect system away from the divergence. The integrated system takes advantages of SINS, GPS and CNS to an immense improvement for high accuracy and reliably high dynamic navigation application. Simulation result shows that federated fusion of using GPS and CNS to revise SINS solution is reasonable and availably with good estimation performance, which are satisfied with the demands of high dynamic flight navigation. The UKF is superior than EKF based integrated scheme, in which has smaller estimation error and quickly convergence rate.

Reconciling Streamflow Uncertainty Estimation and River Bed Morphology Dynamics. Insights from a Probabilistic Assessment of Streamflow Uncertainties Using a Reliability Diagram

NASA Astrophysics Data System (ADS)

Morlot, T.; Mathevet, T.; Perret, C.; Favre Pugin, A. C.

2014-12-01

Streamflow uncertainty estimation has recently received a large attention in the literature. A dynamic rating curve assessment method has been introduced (Morlot et al., 2014). This dynamic method allows to compute a rating curve for each gauging and a continuous streamflow time-series, while calculating streamflow uncertainties. Streamflow uncertainty takes into account many sources of uncertainty (water level, rating curve interpolation and extrapolation, gauging aging, etc.) and produces an estimated distribution of streamflow for each days. In order to caracterise streamflow uncertainty, a probabilistic framework has been applied on a large sample of hydrometric stations of the Division Technique Générale (DTG) of Électricité de France (EDF) hydrometric network (>250 stations) in France. A reliability diagram (Wilks, 1995) has been constructed for some stations, based on the streamflow distribution estimated for a given day and compared to a real streamflow observation estimated via a gauging. To build a reliability diagram, we computed the probability of an observed streamflow (gauging), given the streamflow distribution. Then, the reliability diagram allows to check that the distribution of probabilities of non-exceedance of the gaugings follows a uniform law (i.e., quantiles should be equipropables). Given the shape of the reliability diagram, the probabilistic calibration is caracterised (underdispersion, overdispersion, bias) (Thyer et al., 2009). In this paper, we present case studies where reliability diagrams have different statistical properties for different periods. Compared to our knowledge of river bed morphology dynamic of these hydrometric stations, we show how reliability diagram gives us invaluable information on river bed movements, like a continuous digging or backfilling of the hydraulic control due to erosion or sedimentation processes. Hence, the careful analysis of reliability diagrams allows to reconcile statistics and long-term river bed morphology processes. This knowledge improves our real-time management of hydrometric stations, given a better caracterisation of erosion/sedimentation processes and the stability of hydrometric station hydraulic control.

Detecting affiliation in colaughter across 24 societies

PubMed Central

Bryant, Gregory A.; Fessler, Daniel M. T.; Clint, Edward; Aarøe, Lene; Apicella, Coren L.; Petersen, Michael Bang; Bickham, Shaneikiah T.; Bolyanatz, Alexander; Chavez, Brenda; De Smet, Delphine; Díaz, Cinthya; Fančovičová, Jana; Fux, Michal; Giraldo-Perez, Paulina; Hu, Anning; Kamble, Shanmukh V.; Kameda, Tatsuya; Li, Norman P.; Luberti, Francesca R.; Prokop, Pavol; Quintelier, Katinka; Scelza, Brooke A.; Shin, Hyun Jung; Soler, Montserrat; Stieger, Stefan; van den Hende, Ellis A.; Viciana-Asensio, Hugo; Yildizhan, Saliha Elif; Yong, Jose C.; Yuditha, Tessa; Zhou, Yi

2016-01-01

Laughter is a nonverbal vocal expression that often communicates positive affect and cooperative intent in humans. Temporally coincident laughter occurring within groups is a potentially rich cue of affiliation to overhearers. We examined listeners’ judgments of affiliation based on brief, decontextualized instances of colaughter between either established friends or recently acquainted strangers. In a sample of 966 participants from 24 societies, people reliably distinguished friends from strangers with an accuracy of 53–67%. Acoustic analyses of the individual laughter segments revealed that, across cultures, listeners’ judgments were consistently predicted by voicing dynamics, suggesting perceptual sensitivity to emotionally triggered spontaneous production. Colaughter affords rapid and accurate appraisals of affiliation that transcend cultural and linguistic boundaries, and may constitute a universal means of signaling cooperative relationships. PMID:27071114

An efficient predictor-corrector-based dynamic mesh method for multi-block structured grid with extremely large deformation and its applications

NASA Astrophysics Data System (ADS)

Guo, Tongqing; Chen, Hao; Lu, Zhiliang

2018-05-01

Aiming at extremely large deformation, a novel predictor-corrector-based dynamic mesh method for multi-block structured grid is proposed. In this work, the dynamic mesh generation is completed in three steps. At first, some typical dynamic positions are selected and high-quality multi-block grids with the same topology are generated at those positions. Then, Lagrange interpolation method is adopted to predict the dynamic mesh at any dynamic position. Finally, a rapid elastic deforming technique is used to correct the small deviation between the interpolated geometric configuration and the actual instantaneous one. Compared with the traditional methods, the results demonstrate that the present method shows stronger deformation ability and higher dynamic mesh quality.

Decentralized Fuzzy MPC on Spatial Power Control of a Large PHWR

NASA Astrophysics Data System (ADS)

Liu, Xiangjie; Jiang, Di; Lee, Kwang Y.

2016-08-01

Reliable power control for stabilizing the spatial oscillations is quite important for ensuring the safe operation of a modern pressurized heavy water reactor (PHWR), since these spatial oscillations can cause “flux tilting” in the reactor core. In this paper, a decentralized fuzzy model predictive control (DFMPC) is proposed for spatial control of PHWR. Due to the load dependent dynamics of the nuclear power plant, fuzzy modeling is used to approximate the nonlinear process. A fuzzy Lyapunov function and “quasi-min-max” strategy is utilized in designing the DFMPC, to reduce the conservatism. The plant-wide stability is achieved by the asymptotically positive realness constraint (APRC) for this decentralized MPC. The solving optimization problem is based on a receding horizon scheme involving the linear matrix inequalities (LMIs) technique. Through dynamic simulations, it is demonstrated that the designed DFMPC can effectively suppress spatial oscillations developed in PHWR, and further, shows the advantages over the typical parallel distributed compensation (PDC) control scheme.

Drag balance Cubesat attitude motion effects on in-situ thermosphere density measurements

NASA Astrophysics Data System (ADS)

Felicetti, Leonard; Santoni, Fabio

2014-08-01

The dynamics of Cubesats carrying a drag balance instrument (DBI) for in situ atmosphere density measurements is analyzed. Atmospheric drag force is measured by the displacement of two light plates exposed to the incoming particle flow. This system is well suited for a distributed sensor network in orbit, to get simultaneous in situ local (non orbit averaged) measurements in multiple positions and orbit heights, contributing to the development and validation of global atmosphere models. The implementation of the DBI leads to orbit normal pointing spinning two body system. The use of a spin-magnetic attitude control system is suggested, based only on magnetometer readings, contributing to making the system simple, inexpensive, and reliable. It is shown, by an averaging technique, that this system provides for orbit normal spin axis pointing. The effect of the coupling between the attitude dynamics and the DBI is evaluated, analyzing its frequency content and showing that no frequency components arise, affecting the DBI performance. The analysis is confirmed by Monte Carlo numerical simulation results.

A computer-based measure of resultant achievement motivation.

PubMed

Blankenship, V

1987-08-01

Three experiments were conducted to develop a computer-based measure of individual differences in resultant achievement motivation (RAM) on the basis of level-of-aspiration, achievement motivation, and dynamics-of-action theories. In Experiment 1, the number of atypical shifts and greater responsiveness to incentives on 21 trials with choices among easy, intermediate, and difficult levels of an achievement-oriented game were positively correlated and were found to differentiate the 62 subjects (31 men, 31 women) on the amount of time they spent at a nonachievement task (watching a color design) 1 week later. In Experiment 2, test-retest reliability was established with the use of 67 subjects (15 men, 52 women). Point and no-point trials were offered in blocks, with point trials first for half the subjects and no-point trials first for the other half. Reliability was higher for the atypical-shift measure than for the incentive-responsiveness measure and was higher when points were offered first. In Experiment 3, computer anxiety was manipulated by creating a simulated computer breakdown in the experimental condition. Fifty-nine subjects (13 men, 46 women) were randomly assigned to the experimental condition or to one of two control conditions (an interruption condition and a no-interruption condition). Subjects with low RAM, as demonstrated by a low number of typical shifts, took longer to choose the achievement-oriented task, as predicted by the dynamics-of-action theory. The difference was evident in all conditions and most striking in the computer-breakdown condition. A change of focus from atypical to typical shifts is discussed.

Distributed collaborative probabilistic design for turbine blade-tip radial running clearance using support vector machine of regression

NASA Astrophysics Data System (ADS)

Fei, Cheng-Wei; Bai, Guang-Chen

2014-12-01

To improve the computational precision and efficiency of probabilistic design for mechanical dynamic assembly like the blade-tip radial running clearance (BTRRC) of gas turbine, a distribution collaborative probabilistic design method-based support vector machine of regression (SR)(called as DCSRM) is proposed by integrating distribution collaborative response surface method and support vector machine regression model. The mathematical model of DCSRM is established and the probabilistic design idea of DCSRM is introduced. The dynamic assembly probabilistic design of aeroengine high-pressure turbine (HPT) BTRRC is accomplished to verify the proposed DCSRM. The analysis results reveal that the optimal static blade-tip clearance of HPT is gained for designing BTRRC, and improving the performance and reliability of aeroengine. The comparison of methods shows that the DCSRM has high computational accuracy and high computational efficiency in BTRRC probabilistic analysis. The present research offers an effective way for the reliability design of mechanical dynamic assembly and enriches mechanical reliability theory and method.

Development of a morphology-based modeling technique for tracking solid-body displacements: examining the reliability of a potential MRI-only approach for joint kinematics assessment.

PubMed

Mahato, Niladri K; Montuelle, Stephane; Cotton, John; Williams, Susan; Thomas, James; Clark, Brian

2016-05-18

Single or biplanar video radiography and Roentgen stereophotogrammetry (RSA) techniques used for the assessment of in-vivo joint kinematics involves application of ionizing radiation, which is a limitation for clinical research involving human subjects. To overcome this limitation, our long-term goal is to develop a magnetic resonance imaging (MRI)-only, three dimensional (3-D) modeling technique that permits dynamic imaging of joint motion in humans. Here, we present our initial findings, as well as reliability data, for an MRI-only protocol and modeling technique. We developed a morphology-based motion-analysis technique that uses MRI of custom-built solid-body objects to animate and quantify experimental displacements between them. The technique involved four major steps. First, the imaging volume was calibrated using a custom-built grid. Second, 3-D models were segmented from axial scans of two custom-built solid-body cubes. Third, these cubes were positioned at pre-determined relative displacements (translation and rotation) in the magnetic resonance coil and scanned with a T1 and a fast contrast-enhanced pulse sequences. The digital imaging and communications in medicine (DICOM) images were then processed for animation. The fourth step involved importing these processed images into an animation software, where they were displayed as background scenes. In the same step, 3-D models of the cubes were imported into the animation software, where the user manipulated the models to match their outlines in the scene (rotoscoping) and registered the models into an anatomical joint system. Measurements of displacements obtained from two different rotoscoping sessions were tested for reliability using coefficient of variations (CV), intraclass correlation coefficients (ICC), Bland-Altman plots, and Limits of Agreement analyses. Between-session reliability was high for both the T1 and the contrast-enhanced sequences. Specifically, the average CVs for translation were 4.31 % and 5.26 % for the two pulse sequences, respectively, while the ICCs were 0.99 for both. For rotation measures, the CVs were 3.19 % and 2.44 % for the two pulse sequences with the ICCs being 0.98 and 0.97, respectively. A novel biplanar imaging approach also yielded high reliability with mean CVs of 2.66 % and 3.39 % for translation in the x- and z-planes, respectively, and ICCs of 0.97 in both planes. This work provides basic proof-of-concept for a reliable marker-less non-ionizing-radiation-based quasi-dynamic motion quantification technique that can potentially be developed into a tool for real-time joint kinematics analysis.

Model-Based Heterogeneous Data Fusion for Reliable Force Estimation in Dynamic Structures under Uncertainties

PubMed Central

Khodabandeloo, Babak; Melvin, Dyan; Jo, Hongki

2017-01-01

Direct measurements of external forces acting on a structure are infeasible in many cases. The Augmented Kalman Filter (AKF) has several attractive features that can be utilized to solve the inverse problem of identifying applied forces, as it requires the dynamic model and the measured responses of structure at only a few locations. But, the AKF intrinsically suffers from numerical instabilities when accelerations, which are the most common response measurements in structural dynamics, are the only measured responses. Although displacement measurements can be used to overcome the instability issue, the absolute displacement measurements are challenging and expensive for full-scale dynamic structures. In this paper, a reliable model-based data fusion approach to reconstruct dynamic forces applied to structures using heterogeneous structural measurements (i.e., strains and accelerations) in combination with AKF is investigated. The way of incorporating multi-sensor measurements in the AKF is formulated. Then the formulation is implemented and validated through numerical examples considering possible uncertainties in numerical modeling and sensor measurement. A planar truss example was chosen to clearly explain the formulation, while the method and formulation are applicable to other structures as well. PMID:29149088

Dynamic Assessment of School-Age Children's Narrative Ability: An Experimental Investigation of Classification Accuracy

ERIC Educational Resources Information Center

Pena, Elizabeth D.; Gillam, Ronald B.; Malek, Melynn; Ruiz-Felter, Roxanna; Resendiz, Maria; Fiestas, Christine; Sabel, Tracy

2006-01-01

Two experiments examined reliability and classification accuracy of a narration-based dynamic assessment task. Purpose: The first experiment evaluated whether parallel results were obtained from stories created in response to 2 different wordless picture books. If so, the tasks and measures would be appropriate for assessing pretest and posttest…

Fault tolerant operation of switched reluctance machine

NASA Astrophysics Data System (ADS)

Wang, Wei

The energy crisis and environmental challenges have driven industry towards more energy efficient solutions. With nearly 60% of electricity consumed by various electric machines in industry sector, advancement in the efficiency of the electric drive system is of vital importance. Adjustable speed drive system (ASDS) provides excellent speed regulation and dynamic performance as well as dramatically improved system efficiency compared with conventional motors without electronics drives. Industry has witnessed tremendous grow in ASDS applications not only as a driving force but also as an electric auxiliary system for replacing bulky and low efficiency auxiliary hydraulic and mechanical systems. With the vast penetration of ASDS, its fault tolerant operation capability is more widely recognized as an important feature of drive performance especially for aerospace, automotive applications and other industrial drive applications demanding high reliability. The Switched Reluctance Machine (SRM), a low cost, highly reliable electric machine with fault tolerant operation capability, has drawn substantial attention in the past three decades. Nevertheless, SRM is not free of fault. Certain faults such as converter faults, sensor faults, winding shorts, eccentricity and position sensor faults are commonly shared among all ASDS. In this dissertation, a thorough understanding of various faults and their influence on transient and steady state performance of SRM is developed via simulation and experimental study, providing necessary knowledge for fault detection and post fault management. Lumped parameter models are established for fast real time simulation and drive control. Based on the behavior of the faults, a fault detection scheme is developed for the purpose of fast and reliable fault diagnosis. In order to improve the SRM power and torque capacity under faults, the maximum torque per ampere excitation are conceptualized and validated through theoretical analysis and experiments. With the proposed optimal waveform, torque production is greatly improved under the same Root Mean Square (RMS) current constraint. Additionally, position sensorless operation methods under phase faults are investigated to account for the combination of physical position sensor and phase winding faults. A comprehensive solution for position sensorless operation under single and multiple phases fault are proposed and validated through experiments. Continuous position sensorless operation with seamless transition between various numbers of phase fault is achieved.

Inferential modeling and predictive feedback control in real-time motion compensation using the treatment couch during radiotherapy

NASA Astrophysics Data System (ADS)

Qiu, Peng; D'Souza, Warren D.; McAvoy, Thomas J.; Liu, K. J. Ray

2007-09-01

Tumor motion induced by respiration presents a challenge to the reliable delivery of conformal radiation treatments. Real-time motion compensation represents the technologically most challenging clinical solution but has the potential to overcome the limitations of existing methods. The performance of a real-time couch-based motion compensation system is mainly dependent on two aspects: the ability to infer the internal anatomical position and the performance of the feedback control system. In this paper, we propose two novel methods for the two aspects respectively, and then combine the proposed methods into one system. To accurately estimate the internal tumor position, we present partial-least squares (PLS) regression to predict the position of the diaphragm using skin-based motion surrogates. Four radio-opaque markers were placed on the abdomen of patients who underwent fluoroscopic imaging of the diaphragm. The coordinates of the markers served as input variables and the position of the diaphragm served as the output variable. PLS resulted in lower prediction errors compared with standard multiple linear regression (MLR). The performance of the feedback control system depends on the system dynamics and dead time (delay between the initiation and execution of the control action). While the dynamics of the system can be inverted in a feedback control system, the dead time cannot be inverted. To overcome the dead time of the system, we propose a predictive feedback control system by incorporating forward prediction using least-mean-square (LMS) and recursive least square (RLS) filtering into the couch-based control system. Motion data were obtained using a skin-based marker. The proposed predictive feedback control system was benchmarked against pure feedback control (no forward prediction) and resulted in a significant performance gain. Finally, we combined the PLS inference model and the predictive feedback control to evaluate the overall performance of the feedback control system. Our results show that, with the tumor motion unknown but inferred by skin-based markers through the PLS model, the predictive feedback control system was able to effectively compensate intra-fraction motion.

High Fidelity, “Faster than Real-Time” Simulator for Predicting Power System Dynamic Behavior - Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flueck, Alex

The “High Fidelity, Faster than Real­Time Simulator for Predicting Power System Dynamic Behavior” was designed and developed by Illinois Institute of Technology with critical contributions from Electrocon International, Argonne National Laboratory, Alstom Grid and McCoy Energy. Also essential to the project were our two utility partners: Commonwealth Edison and AltaLink. The project was a success due to several major breakthroughs in the area of large­scale power system dynamics simulation, including (1) a validated faster than real­ time simulation of both stable and unstable transient dynamics in a large­scale positive sequence transmission grid model, (2) a three­phase unbalanced simulation platform formore » modeling new grid devices, such as independently controlled single­phase static var compensators (SVCs), (3) the world’s first high fidelity three­phase unbalanced dynamics and protection simulator based on Electrocon’s CAPE program, and (4) a first­of­its­ kind implementation of a single­phase induction motor model with stall capability. The simulator results will aid power grid operators in their true time of need, when there is a significant risk of cascading outages. The simulator will accelerate performance and enhance accuracy of dynamics simulations, enabling operators to maintain reliability and steer clear of blackouts. In the long­term, the simulator will form the backbone of the newly conceived hybrid real­time protection and control architecture that will coordinate local controls, wide­area measurements, wide­area controls and advanced real­time prediction capabilities. The nation’s citizens will benefit in several ways, including (1) less down time from power outages due to the faster­than­real­time simulator’s predictive capability, (2) higher levels of reliability due to the detailed dynamics plus protection simulation capability, and (3) more resiliency due to the three­ phase unbalanced simulator’s ability to model three­phase and single­ phase networks and devices.« less

Blind system identification of two-thermocouple sensor based on cross-relation method.

PubMed

Li, Yanfeng; Zhang, Zhijie; Hao, Xiaojian

2018-03-01

In dynamic temperature measurement, the dynamic characteristics of the sensor affect the accuracy of the measurement results. Thermocouples are widely used for temperature measurement in harsh conditions due to their low cost, robustness, and reliability, but because of the presence of the thermal inertia, there is a dynamic error in the dynamic temperature measurement. In order to eliminate the dynamic error, two-thermocouple sensor was used to measure dynamic gas temperature in constant velocity flow environments in this paper. Blind system identification of two-thermocouple sensor based on a cross-relation method was carried out. Particle swarm optimization algorithm was used to estimate time constants of two thermocouples and compared with the grid based search method. The method was validated on the experimental equipment built by using high temperature furnace, and the input dynamic temperature was reconstructed by using the output data of the thermocouple with small time constant.

Blind system identification of two-thermocouple sensor based on cross-relation method

NASA Astrophysics Data System (ADS)

Li, Yanfeng; Zhang, Zhijie; Hao, Xiaojian

2018-03-01

In dynamic temperature measurement, the dynamic characteristics of the sensor affect the accuracy of the measurement results. Thermocouples are widely used for temperature measurement in harsh conditions due to their low cost, robustness, and reliability, but because of the presence of the thermal inertia, there is a dynamic error in the dynamic temperature measurement. In order to eliminate the dynamic error, two-thermocouple sensor was used to measure dynamic gas temperature in constant velocity flow environments in this paper. Blind system identification of two-thermocouple sensor based on a cross-relation method was carried out. Particle swarm optimization algorithm was used to estimate time constants of two thermocouples and compared with the grid based search method. The method was validated on the experimental equipment built by using high temperature furnace, and the input dynamic temperature was reconstructed by using the output data of the thermocouple with small time constant.

A study of low-cost reliable actuators for light aircraft. Part A: Chapters 1-8

NASA Technical Reports Server (NTRS)

Eijsink, H.; Rice, M.

1978-01-01

An analysis involving electro-mechanical, electro-pneumatic, and electro-hydraulic actuators was performed to study which are compatible for use in the primary and secondary flight controls of a single engine light aircraft. Actuator characteristics under investigation include cost, reliability, weight, force, volumetric requirements, power requirements, response characteristics and heat accumulation characteristics. The basic types of actuators were compared for performance characteristics in positioning a control surface model and then were mathematically evaluated in an aircraft to get the closed loop dynamic response characteristics. Conclusions were made as to the suitability of each actuator type for use in an aircraft.

Quantitative assessment of human motion using video motion analysis

NASA Technical Reports Server (NTRS)

Probe, John D.

1990-01-01

In the study of the dynamics and kinematics of the human body, a wide variety of technologies was developed. Photogrammetric techniques are well documented and are known to provide reliable positional data from recorded images. Often these techniques are used in conjunction with cinematography and videography for analysis of planar motion, and to a lesser degree three-dimensional motion. Cinematography has been the most widely used medium for movement analysis. Excessive operating costs and the lag time required for film development coupled with recent advances in video technology have allowed video based motion analysis systems to emerge as a cost effective method of collecting and analyzing human movement. The Anthropometric and Biomechanics Lab at Johnson Space Center utilizes the video based Ariel Performance Analysis System to develop data on shirt-sleeved and space-suited human performance in order to plan efficient on orbit intravehicular and extravehicular activities. The system is described.

Single molecule characterization of DNA binding and strand displacement reactions on lithographic DNA origami microarrays.

PubMed

Scheible, Max B; Pardatscher, Günther; Kuzyk, Anton; Simmel, Friedrich C

2014-03-12

The combination of molecular self-assembly based on the DNA origami technique with lithographic patterning enables the creation of hierarchically ordered nanosystems, in which single molecules are positioned at precise locations on multiple length scales. Based on a hybrid assembly protocol utilizing DNA self-assembly and electron-beam lithography on transparent glass substrates, we here demonstrate a DNA origami microarray, which is compatible with the requirements of single molecule fluorescence and super-resolution microscopy. The spatial arrangement allows for a simple and reliable identification of single molecule events and facilitates automated read-out and data analysis. As a specific application, we utilize the microarray to characterize the performance of DNA strand displacement reactions localized on the DNA origami structures. We find considerable variability within the array, which results both from structural variations and stochastic reaction dynamics prevalent at the single molecule level.

Segmentation and classification of cell cycle phases in fluorescence imaging.

PubMed

Ersoy, Ilker; Bunyak, Filiz; Chagin, Vadim; Cardoso, M Christina; Palaniappan, Kannappan

2009-01-01

Current chemical biology methods for studying spatiotemporal correlation between biochemical networks and cell cycle phase progression in live-cells typically use fluorescence-based imaging of fusion proteins. Stable cell lines expressing fluorescently tagged protein GFP-PCNA produce rich, dynamically varying sub-cellular foci patterns characterizing the cell cycle phases, including the progress during the S-phase. Variable fluorescence patterns, drastic changes in SNR, shape and position changes and abundance of touching cells require sophisticated algorithms for reliable automatic segmentation and cell cycle classification. We extend the recently proposed graph partitioning active contours (GPAC) for fluorescence-based nucleus segmentation using regional density functions and dramatically improve its efficiency, making it scalable for high content microscopy imaging. We utilize surface shape properties of GFP-PCNA intensity field to obtain descriptors of foci patterns and perform automated cell cycle phase classification, and give quantitative performance by comparing our results to manually labeled data.

Cell segmentation in time-lapse fluorescence microscopy with temporally varying sub-cellular fusion protein patterns.

PubMed

Bunyak, Filiz; Palaniappan, Kannappan; Chagin, Vadim; Cardoso, M

2009-01-01

Fluorescently tagged proteins such as GFP-PCNA produce rich dynamically varying textural patterns of foci distributed in the nucleus. This enables the behavioral study of sub-cellular structures during different phases of the cell cycle. The varying punctuate patterns of fluorescence, drastic changes in SNR, shape and position during mitosis and abundance of touching cells, however, require more sophisticated algorithms for reliable automatic cell segmentation and lineage analysis. Since the cell nuclei are non-uniform in appearance, a distribution-based modeling of foreground classes is essential. The recently proposed graph partitioning active contours (GPAC) algorithm supports region descriptors and flexible distance metrics. We extend GPAC for fluorescence-based cell segmentation using regional density functions and dramatically improve its efficiency for segmentation from O(N(4)) to O(N(2)), for an image with N(2) pixels, making it practical and scalable for high throughput microscopy imaging studies.

Adaptive Indoor Positioning Model Based on WLAN-Fingerprinting for Dynamic and Multi-Floor Environments

PubMed Central

Alshami, Iyad Husni; Sahibuddin, Shamsul; Firdaus, Firdaus

2017-01-01

The Global Positioning System demonstrates the significance of Location Based Services but it cannot be used indoors due to the lack of line of sight between satellites and receivers. Indoor Positioning Systems are needed to provide indoor Location Based Services. Wireless LAN fingerprints are one of the best choices for Indoor Positioning Systems because of their low cost, and high accuracy, however they have many drawbacks: creating radio maps is time consuming, the radio maps will become outdated with any environmental change, different mobile devices read the received signal strength (RSS) differently, and peoples’ presence in LOS between access points and mobile device affects the RSS. This research proposes a new Adaptive Indoor Positioning System model (called DIPS) based on: a dynamic radio map generator, RSS certainty technique and peoples’ presence effect integration for dynamic and multi-floor environments. Dynamic in our context refers to the effects of people and device heterogeneity. DIPS can achieve 98% and 92% positioning accuracy for floor and room positioning, and it achieves 1.2 m for point positioning error. RSS certainty enhanced the positioning accuracy for floor and room for different mobile devices by 11% and 9%. Then by considering the peoples’ presence effect, the error is reduced by 0.2 m. In comparison with other works, DIPS achieves better positioning without extra devices. PMID:28783047

The V-band Empirical Mass-luminosity Relation for Main Sequence Stars

NASA Astrophysics Data System (ADS)

Xia, Fang; Fu, Yan-Ning

2010-07-01

Stellar mass is an indispensable parameter in the studies of stellar physics and stellar dynamics. On the one hand, the most reliable way to determine the stellar dynamical mass is via orbital determinations of binaries. On the other hand, however, most stellar masses have to be estimated by using the mass luminosity relation (MLR). Therefore, it is important to obtain the empirical MLR through fitting the data of stellar dynamical mass and luminosity. The effect of metallicity can make this relation disperse in the V-band, but studies show that this is mainly limited to the case when the stellar mass is less than 0.6M⊙ Recently, many relevant data have been accumulated for main sequence stars with larger masses, which make it possible to significantly improve the corresponding MLR. Using a fitting method which can reasonably assign weights to the observational data including two quantities with different dimensions, we obtain a V-band MLR based on the dynamical masses and luminosities of 203 main sequence stars. In comparison with the previous work, the improved MLR is statistically significant, and the relative error of mass estimation reaches about 5%. Therefore, our MLR is useful not only in the studies of statistical nature, but also in the studies of concrete stellar systems, such as the long-term dynamical study and the short-term positioning study of a specific multiple star system.

The V Band Empirical Mass-Luminosity Relation for Main Sequence Stars

NASA Astrophysics Data System (ADS)

Xia, F.; Fu, Y. N.

2010-01-01

Stellar mass is an indispensable parameter in the studies of stellar physics and stellar dynamics. On the one hand, the most reliable way to determine the stellar dynamical mass is via orbital determination of binaries. On the other hand, however, most stellar masses have to be estimated by using the mass-luminosity relation (MLR). Therefore, it is important to obtain the empirical MLR through fitting the data of stellar dynamical mass and luminosity. The effect of metallicity can make this relation disperse in the V-band, but studies show that this is mainly limited to the case when the stellar mass is less than 0.6M⊙. Recently, many relevant data have been accumulated for main sequence stars with larger mass, which make it possible to significantly improve the corresponding MLR. Using a fitting method which can reasonably assign weight to the observational data including two quantities with different dimensions, we obtain a V-band MLR based on the dynamical masses and luminosities of 203 main sequence stars. Compared with the previous work, the improved MLR is statistically significant, and the relative error of mass estimation reaches about 5%. Therefore, our MLR is useful not only in studies of statistical nature, but also in studies of concrete stellar systems, such as the long-term dynamical study and the short-term positioning study of a specific multiple star system.

Reliability and validity of a novel Kinect-based software program for measuring posture, balance and side-bending.

PubMed

Grooten, Wilhelmus Johannes Andreas; Sandberg, Lisa; Ressman, John; Diamantoglou, Nicolas; Johansson, Elin; Rasmussen-Barr, Eva

2018-01-08

Clinical examinations are subjective and often show a low validity and reliability. Objective and highly reliable quantitative assessments are available in laboratory settings using 3D motion analysis, but these systems are too expensive to use for simple clinical examinations. Qinematic™ is an interactive movement analyses system based on the Kinect camera and is an easy-to-use clinical measurement system for assessing posture, balance and side-bending. The aim of the study was to test the test-retest the reliability and construct validity of Qinematic™ in a healthy population, and to calculate the minimal clinical differences for the variables of interest. A further aim was to identify the discriminative validity of Qinematic™ in people with low-back pain (LBP). We performed a test-retest reliability study (n = 37) with around 1 week between the occasions, a construct validity study (n = 30) in which Qinematic™ was tested against a 3D motion capture system, and a discriminative validity study, in which a group of people with LBP (n = 20) was compared to healthy controls (n = 17). We tested a large range of psychometric properties of 18 variables in three sections: posture (head and pelvic position, weight distribution), balance (sway area and velocity in single- and double-leg stance), and side-bending. The majority of the variables in the posture and balance sections, showed poor/fair reliability (ICC < 0.4) and poor/fair validity (Spearman <0.4), with significant differences between occasions, between Qinematic™ and the 3D-motion capture system. In the clinical study, Qinematic™ did not differ between people with LPB and healthy for these variables. For one variable, side-bending to the left, there was excellent reliability (ICC =0.898), excellent validity (r = 0.943), and Qinematic™ could differentiate between LPB and healthy individuals (p = 0.012). This paper shows that a novel software program (Qinematic™) based on the Kinect camera for measuring balance, posture and side-bending has poor psychometric properties, indicating that the variables on balance and posture should not be used for monitoring individual changes over time or in research. Future research on the dynamic tasks of Qinematic™ is warranted.

Multi-hop routing mechanism for reliable sensor computing.

PubMed

Chen, Jiann-Liang; Ma, Yi-Wei; Lai, Chia-Ping; Hu, Chia-Cheng; Huang, Yueh-Min

2009-01-01

Current research on routing in wireless sensor computing concentrates on increasing the service lifetime, enabling scalability for large number of sensors and supporting fault tolerance for battery exhaustion and broken nodes. A sensor node is naturally exposed to various sources of unreliable communication channels and node failures. Sensor nodes have many failure modes, and each failure degrades the network performance. This work develops a novel mechanism, called Reliable Routing Mechanism (RRM), based on a hybrid cluster-based routing protocol to specify the best reliable routing path for sensor computing. Table-driven intra-cluster routing and on-demand inter-cluster routing are combined by changing the relationship between clusters for sensor computing. Applying a reliable routing mechanism in sensor computing can improve routing reliability, maintain low packet loss, minimize management overhead and save energy consumption. Simulation results indicate that the reliability of the proposed RRM mechanism is around 25% higher than that of the Dynamic Source Routing (DSR) and ad hoc On-demand Distance Vector routing (AODV) mechanisms.

Perceptual attraction in tool use: evidence for a reliability-based weighting mechanism.

PubMed

Debats, Nienke B; Ernst, Marc O; Heuer, Herbert

2017-04-01

Humans are well able to operate tools whereby their hand movement is linked, via a kinematic transformation, to a spatially distant object moving in a separate plane of motion. An everyday example is controlling a cursor on a computer monitor. Despite these separate reference frames, the perceived positions of the hand and the object were found to be biased toward each other. We propose that this perceptual attraction is based on the principles by which the brain integrates redundant sensory information of single objects or events, known as optimal multisensory integration. That is, 1 ) sensory information about the hand and the tool are weighted according to their relative reliability (i.e., inverse variances), and 2 ) the unisensory reliabilities sum up in the integrated estimate. We assessed whether perceptual attraction is consistent with optimal multisensory integration model predictions. We used a cursor-control tool-use task in which we manipulated the relative reliability of the unisensory hand and cursor position estimates. The perceptual biases shifted according to these relative reliabilities, with an additional bias due to contextual factors that were present in experiment 1 but not in experiment 2 The biased position judgments' variances were, however, systematically larger than the predicted optimal variances. Our findings suggest that the perceptual attraction in tool use results from a reliability-based weighting mechanism similar to optimal multisensory integration, but that certain boundary conditions for optimality might not be satisfied. NEW & NOTEWORTHY Kinematic tool use is associated with a perceptual attraction between the spatially separated hand and the effective part of the tool. We provide a formal account for this phenomenon, thereby showing that the process behind it is similar to optimal integration of sensory information relating to single objects. Copyright © 2017 the American Physiological Society.

The Design and Implementation of Indoor Localization System Using Magnetic Field Based on Smartphone

NASA Astrophysics Data System (ADS)

Liu, J.; Jiang, C.; Shi, Z.

2017-09-01

Sufficient signal nodes are mostly required to implement indoor localization in mainstream research. Magnetic field take advantage of high precision, stable and reliability, and the reception of magnetic field signals is reliable and uncomplicated, it could be realized by geomagnetic sensor on smartphone, without external device. After the study of indoor positioning technologies, choose the geomagnetic field data as fingerprints to design an indoor localization system based on smartphone. A localization algorithm that appropriate geomagnetic matching is designed, and present filtering algorithm and algorithm for coordinate conversion. With the implement of plot geomagnetic fingerprints, the indoor positioning of smartphone without depending on external devices can be achieved. Finally, an indoor positioning system which is based on Android platform is successfully designed, through the experiments, proved the capability and effectiveness of indoor localization algorithm.

Cortical geometry may influence placement of interface between Par protein domains in early Caenorhabditis elegans embryos.

PubMed

Dawes, Adriana T; Iron, David

2013-09-21

During polarization, proteins and other polarity determinants segregate to the opposite ends of the cell (the poles) creating biochemically and dynamically distinct regions. Embryos of the nematode worm Caenorhabditis elegans (C. elegans) polarize shortly after fertilization, creating distinct regions of Par protein family members. These regions are maintained through to first cleavage when the embryo divides along the plane specified by the interface between regions, creating daughter cells with different protein content. In wild type single cell embryos the interface between these Par protein regions is reliably positioned at approximately 60% egg length, however, it is not known what mechanisms are responsible for specifying the position of the interface. In this investigation, we use two mathematical models to investigate the movement and positioning of the interface: a biologically based reaction-diffusion model of Par protein dynamics, and the analytically tractable perturbed Allen-Cahn equation. When we numerically simulate the models on a static 2D domain with constant thickness, both models exhibit a persistently moving interface that specifies the boundary between distinct regions. When we modify the simulation domain geometry, movement halts and the interface is stably positioned where the domain thickness increases. Using asymptotic analysis with the perturbed Allen-Cahn equation, we show that interface movement depends explicitly on domain geometry. Using a combination of analytic and numeric techniques, we demonstrate that domain geometry, a historically overlooked aspect of cellular simulations, may play a significant role in spatial protein patterning during polarization. Copyright © 2013 Elsevier Ltd. All rights reserved.

Model-based chatter stability prediction and detection for the turning of a flexible workpiece

NASA Astrophysics Data System (ADS)

Lu, Kaibo; Lian, Zisheng; Gu, Fengshou; Liu, Hunju

2018-02-01

Machining long slender workpieces still presents a technical challenge on the shop floor due to their low stiffness and damping. Regenerative chatter is a major hindrance in machining processes, reducing the geometric accuracies and dynamic stability of the cutting system. This study has been motivated by the fact that chatter occurrence is generally in relation to the cutting position in straight turning of slender workpieces, which has seldom been investigated comprehensively in literature. In the present paper, a predictive chatter model of turning a tailstock supported slender workpiece considering the cutting position change during machining is explored. Based on linear stability analysis and stiffness distribution at different cutting positions along the workpiece, the effect of the cutting tool movement along the length of the workpiece on chatter stability is studied. As a result, an entire stability chart for a single cutting pass is constructed. Through this stability chart the critical cutting condition and the chatter onset location along the workpiece in a turning operation can be estimated. The difference between the predicted tool locations and the experimental results was within 9% at high speed cutting. Also, on the basis of the predictive model the dynamic behavior during chatter that when chatter arises at some cutting location it will continue for a period of time until another specified location is arrived at, can be inferred. The experimental observation is in good agreement with the theoretical inference. In chatter detection respect, besides the delay strategy and overlap processing technique, a relative threshold algorithm is proposed to detect chatter by comparing the spectrum and variance of the acquired acceleration signals with the reference saved during stable cutting. The chatter monitoring method has shown reliability for various machining conditions.

[A reliability growth assessment method and its application in the development of equipment in space cabin].

PubMed

Chen, J D; Sun, H L

1999-04-01

Objective. To assess and predict reliability of an equipment dynamically by making full use of various test informations in the development of products. Method. A new reliability growth assessment method based on army material system analysis activity (AMSAA) model was developed. The method is composed of the AMSAA model and test data conversion technology. Result. The assessment and prediction results of a space-borne equipment conform to its expectations. Conclusion. It is suggested that this method should be further researched and popularized.

Life and reliability modeling of bevel gear reductions

NASA Technical Reports Server (NTRS)

Savage, M.; Brikmanis, C. K.; Lewicki, D. G.; Coy, J. J.

1985-01-01

A reliability model is presented for bevel gear reductions with either a single input pinion or dual input pinions of equal size. The dual pinions may or may not have the same power applied for the analysis. The gears may be straddle mounted or supported in a bearing quill. The reliability model is based on the Weibull distribution. The reduction's basic dynamic capacity is defined as the output torque which may be applied for one million output rotations of the bevel gear with a 90 percent probability of reduction survival.

Early Dynamic 68Ga-DOTA-D-Phe1-Tyr3-Octreotide PET/CT in Patients With Hepatic Metastases of Neuroendocrine Tumors.

PubMed

Sänger, Philipp Wilhelm; Freesmeyer, Martin

2016-06-01

Whole-body PET with Ga-DOTA-D-Phe-Tyr-octreotide (Ga-DOTATOC) and contrast-enhanced CT (ceCT) are considered a standard for the staging of neuroendocrine tumors (NETs). This study sought to verify whether early dynamic (ed) Ga-DOTATOC PET/CT can reliably detect liver metastases of NETs (hypervascular, nonhypervascular; positive or negative for somatostatin receptors) and to verify if the receptor positivity has a significant impact on the detection of tumor hypervascularization. Twenty-seven patients with NET were studied by ceCT and standard whole-body PET according to established Ga-DOTATOC protocols. In addition, edPET data were obtained by continuous scanning during the first 300 seconds after bolus injections of the radiotracer. Early dynamic PET required an additional low-dose, native CT image of the liver for the purpose of attenuation correction. Time-activity and time-contrast curves were obtained, the latter being calculated by the difference between tumor and reference regions. Early dynamic PET/CT proved comparable with ceCT in readily identifying hypervascular lesions, irrespective of the receptor status, with activities rising within 16 to 40 seconds. Early dynamic PET/CT also readily identified nonhypervascular, receptor-positive lesions. Positive image contrasts were obtained for hypervascular, receptor-positive lesions, whereas early negative contrasts were obtained for nonhypervascular, receptor-negative lesions. The high image contrast of hypervascular NET metastases in early arterial phases suggests that edPET/CT can become a useful alternative in patients with contraindications to ceCT. The high density of somatostatin receptors did not seem to interfere with the detection of the lesion's hypervascularization.

Unreliability as a Threat to Understanding Psychopathology: The Cautionary Tale of Attentional Bias

PubMed Central

Rodebaugh, Thomas L.; Scullin, Rachel B.; Langer, Julia K.; Dixon, David J.; Huppert, Jonathan D.; Bernstein, Amit; Zvielli, Ariel; Lenze, Eric J.

2016-01-01

The use of unreliable measures constitutes a threat to our understanding of psychopathology, because advancement of science using both behavioral and biologically-oriented measures can only be certain if such measurements are reliable. Two pillars of NIMH’s portfolio – the Research Domain Criteria (RDoC) initiative for psychopathology and the target engagement initiative in clinical trials – cannot succeed without measures that possess the high reliability necessary for tests involving mediation and selection based on individual differences. We focus on the historical lack of reliability of attentional bias measures as an illustration of how reliability can pose a threat to our understanding. Our own data replicate previous findings of poor reliability for traditionally-used scores, which suggests a serious problem with the ability to test theories regarding attentional bias. This lack of reliability may also suggest problems with the assumption (in both theory and the formula for the scores) that attentional bias is consistent and stable across time. In contrast, measures accounting for attention as a dynamic process in time show good reliability in our data. The field is sorely in need of research reporting findings and reliability for attentional bias scores using multiple methods, including those focusing on dynamic processes over time. We urge researchers to test and report reliability of all measures, considering findings of low reliability not just as a nuisance but as an opportunity to modify and improve upon the underlying theory. Full assessment of reliability of measures will maximize the possibility that RDoC (and psychological science more generally) will succeed. PMID:27322741

Reliability Estimation of Aero-engine Based on Mixed Weibull Distribution Model

NASA Astrophysics Data System (ADS)

Yuan, Zhongda; Deng, Junxiang; Wang, Dawei

2018-02-01

Aero-engine is a complex mechanical electronic system, based on analysis of reliability of mechanical electronic system, Weibull distribution model has an irreplaceable role. Till now, only two-parameter Weibull distribution model and three-parameter Weibull distribution are widely used. Due to diversity of engine failure modes, there is a big error with single Weibull distribution model. By contrast, a variety of engine failure modes can be taken into account with mixed Weibull distribution model, so it is a good statistical analysis model. Except the concept of dynamic weight coefficient, in order to make reliability estimation result more accurately, three-parameter correlation coefficient optimization method is applied to enhance Weibull distribution model, thus precision of mixed distribution reliability model is improved greatly. All of these are advantageous to popularize Weibull distribution model in engineering applications.

System life and reliability modeling for helicopter transmissions

NASA Technical Reports Server (NTRS)

Savage, M.; Brikmanis, C. K.

1986-01-01

A computer program which simulates life and reliability of helicopter transmissions is presented. The helicopter transmissions may be composed of spiral bevel gear units and planetary gear units - alone, in series or in parallel. The spiral bevel gear units may have either single or dual input pinions, which are identical. The planetary gear units may be stepped or unstepped and the number of planet gears carried by the planet arm may be varied. The reliability analysis used in the program is based on the Weibull distribution lives of the transmission components. The computer calculates the system lives and dynamic capacities of the transmission components and the transmission. The system life is defined as the life of the component or transmission at an output torque at which the probability of survival is 90 percent. The dynamic capacity of a component or transmission is defined as the output torque which can be applied for one million output shaft cycles for a probability of survival of 90 percent. A complete summary of the life and dynamic capacity results is produced by the program.

Dynamic Inversion based Control of a Docking Mechanism

NASA Technical Reports Server (NTRS)

Kulkarni, Nilesh V.; Ippolito, Corey; Krishnakumar, Kalmanje

2006-01-01

The problem of position and attitude control of the Stewart platform based docking mechanism is considered motivated by its future application in space missions requiring the autonomous docking capability. The control design is initiated based on the framework of the intelligent flight control architecture being developed at NASA Ames Research Center. In this paper, the baseline position and attitude control system is designed using dynamic inversion with proportional-integral augmentation. The inverse dynamics uses a Newton-Euler formulation that includes the platform dynamics, the dynamics of the individual legs along with viscous friction in the joints. Simulation results are presented using forward dynamics simulated by a commercial physics engine that builds the system as individual elements with appropriate joints and uses constrained numerical integration,

Gene expression information improves reliability of receptor status in breast cancer patients

PubMed Central

Kenn, Michael; Schlangen, Karin; Castillo-Tong, Dan Cacsire; Singer, Christian F.; Cibena, Michael; Koelbl, Heinz; Schreiner, Wolfgang

2017-01-01

Immunohistochemical (IHC) determination of receptor status in breast cancer patients is frequently inaccurate. Since it directs the choice of systemic therapy, it is essential to increase its reliability. We increase the validity of IHC receptor expression by additionally considering gene expression (GE) measurements. Crisp therapeutic decisions are based on IHC estimates, even if they are borderline reliable. We further improve decision quality by a responsibility function, defining a critical domain for gene expression. Refined normalization is devised to file any newly diagnosed patient into existing data bases. Our approach renders receptor estimates more reliable by identifying patients with questionable receptor status. The approach is also more efficient since the rate of conclusive samples is increased. We have curated and evaluated gene expression data, together with clinical information, from 2880 breast cancer patients. Combining IHC with gene expression information yields a method more reliable and also more efficient as compared to common practice up to now. Several types of possibly suboptimal treatment allocations, based on IHC receptor status alone, are enumerated. A ‘therapy allocation check’ identifies patients possibly miss-classified. Estrogen: false negative 8%, false positive 6%. Progesterone: false negative 14%, false positive 11%. HER2: false negative 2%, false positive 50%. Possible implications are discussed. We propose an ‘expression look-up-plot’, allowing for a significant potential to improve the quality of precision medicine. Methods are developed and exemplified here for breast cancer patients, but they may readily be transferred to diagnostic data relevant for therapeutic decisions in other fields of oncology. PMID:29100391

Accuracy, intra- and inter-unit reliability, and comparison between GPS and UWB-based position-tracking systems used for time-motion analyses in soccer.

PubMed

Bastida Castillo, Alejandro; Gómez Carmona, Carlos D; De la Cruz Sánchez, Ernesto; Pino Ortega, José

2018-05-01

There is interest in the accuracy and inter-unit reliability of position-tracking systems to monitor players. Research into this technology, although relatively recent, has grown exponentially in the last years, and it is difficult to find professional team sport that does not use Global Positioning System (GPS) technology at least. The aim of this study is to know the accuracy of both GPS-based and Ultra Wide Band (UWB)-based systems on a soccer field and their inter- and intra-unit reliability. A secondary aim is to compare them for practical applications in sport science. Following institutional ethical approval and familiarization, 10 healthy and well-trained former soccer players (20 ± 1.6 years, 1.76 ± 0.08 cm, and 69.5 ± 9.8 kg) performed three course tests: (i) linear course, (ii) circular course, and (iii) a zig-zag course, all using UWB and GPS technologies. The average speed and distance covered were compared with timing gates and the real distance as references. The UWB technology showed better accuracy (bias: 0.57-5.85%), test-retest reliability (%TEM: 1.19), and inter-unit reliability (bias: 0.18) in determining distance covered than the GPS technology (bias: 0.69-6.05%; %TEM: 1.47; bias: 0.25) overall. Also, UWB showed better results (bias: 0.09; ICC: 0.979; bias: 0.01) for mean velocity measurement than GPS (bias: 0.18; ICC: 0.951; bias: 0.03).

Robustness Analysis and Reliable Flight Regime Estimation of an Integrated Resilent Control System for a Transport Aircraft

NASA Technical Reports Server (NTRS)

Shin, Jong-Yeob; Belcastro, Christine

2008-01-01

Formal robustness analysis of aircraft control upset prevention and recovery systems could play an important role in their validation and ultimate certification. As a part of the validation process, this paper describes an analysis method for determining a reliable flight regime in the flight envelope within which an integrated resilent control system can achieve the desired performance of tracking command signals and detecting additive faults in the presence of parameter uncertainty and unmodeled dynamics. To calculate a reliable flight regime, a structured singular value analysis method is applied to analyze the closed-loop system over the entire flight envelope. To use the structured singular value analysis method, a linear fractional transform (LFT) model of a transport aircraft longitudinal dynamics is developed over the flight envelope by using a preliminary LFT modeling software tool developed at the NASA Langley Research Center, which utilizes a matrix-based computational approach. The developed LFT model can capture original nonlinear dynamics over the flight envelope with the ! block which contains key varying parameters: angle of attack and velocity, and real parameter uncertainty: aerodynamic coefficient uncertainty and moment of inertia uncertainty. Using the developed LFT model and a formal robustness analysis method, a reliable flight regime is calculated for a transport aircraft closed-loop system.

Determination of the mental foramen position in dental radiographs in 18-30 year olds.

PubMed

Currie, Charlotte C; Meechan, John G; Whitworth, John M; Carr, Andrew; Corbett, Ian P

2016-01-01

To determine the radiographic position and reliability of assessing mental foramen (MF) position in relation to premolar crowns in an 18- to 30-year-old UK-based population. Following ethical approval and a power calculation, the position of the MF was recorded in relation to premolar crowns and apices in 100 dental panoramic tomographs. Positions were assessed by three senior clinicians independently, then by consensus. Data were analysed using descriptive statistics, χ(2) and Fleiss' and Cohen's kappa. Reliability data showed only fair to moderate agreement on independent scoring. Substantial to almost perfect agreement was achieved by consensus, demonstrating the most common position for the MF to be between the first and second premolar teeth when using both premolar crowns (51%) and apices (76%) as reference points. There was a significant difference in the position of the foramen between the left and right sides (p < 0.05), with only 62% of cases showing symmetry. The most common position for the MF is between the first and second premolar teeth; however, anatomical variation is seen. Use of pre-operative radiographs to relate the position of the MF to premolar crowns may not be reliable.

Beam position monitor engineering

NASA Astrophysics Data System (ADS)

Smith, Stephen R.

1997-01-01

The design of beam position monitors often involves challenging system design choices. Position transducers must be robust, accurate, and generate adequate position signal without unduly disturbing the beam. Electronics must be reliable and affordable, usually while meeting tough requirements on precision, accuracy, and dynamic range. These requirements may be difficult to achieve simultaneously, leading the designer into interesting opportunities for optimization or compromise. Some useful techniques and tools are shown. Both finite element analysis and analytic techniques will be used to investigate quasi-static aspects of electromagnetic fields such as the impedance of and the coupling of beam to striplines or buttons. Finite-element tools will be used to understand dynamic aspects of the electromagnetic fields of beams, such as wake fields and transmission-line and cavity effects in vacuum-to-air feedthroughs. Mathematical modeling of electrical signals through a processing chain will be demonstrated, in particular to illuminate areas where neither a pure time-domain nor a pure frequency-domain analysis is obviously advantageous. Emphasis will be on calculational techniques, in particular on using both time domain and frequency domain approaches to the applicable parts of interesting problems.

Hydrogen positions in single nanocrystals revealed by electron diffraction

NASA Astrophysics Data System (ADS)

Palatinus, L.; Brázda, P.; Boullay, P.; Perez, O.; Klementová, M.; Petit, S.; Eigner, V.; Zaarour, M.; Mintova, S.

2017-01-01

The localization of hydrogen atoms is an essential part of crystal structure analysis, but it is difficult because of their small scattering power. We report the direct localization of hydrogen atoms in nanocrystalline materials, achieved using the recently developed approach of dynamical refinement of precession electron diffraction tomography data. We used this method to locate hydrogen atoms in both an organic (paracetamol) and an inorganic (framework cobalt aluminophosphate) material. The results demonstrate that the technique can reliably reveal fine structural details, including the positions of hydrogen atoms in single crystals with micro- to nanosized dimensions.

Reliable femoral frame construction based on MRI dedicated to muscles position follow-up.

PubMed

Dubois, G; Bonneau, D; Lafage, V; Rouch, P; Skalli, W

2015-10-01

In vivo follow-up of muscle shape variation represents a challenge when evaluating muscle development due to disease or treatment. Recent developments in muscles reconstruction techniques indicate MRI as a clinical tool for the follow-up of the thigh muscles. The comparison of 3D muscles shape from two different sequences is not easy because there is no common frame. This study proposes an innovative method for the reconstruction of a reliable femoral frame based on the femoral head and both condyles centers. In order to robustify the definition of condylar spheres, an original method was developed to combine the estimation of diameters of both condyles from the lateral antero-posterior distance and the estimation of the spheres center from an optimization process. The influence of spacing between MR slices and of origin positions was studied. For all axes, the proposed method presented an angular error lower than 1° with spacing between slice of 10 mm and the optimal position of the origin was identified at 56 % of the distance between the femoral head center and the barycenter of both condyles. The high reliability of this method provides a robust frame for clinical follow-up based on MRI .

A Highly Reliable and Cost-Efficient Multi-Sensor System for Land Vehicle Positioning.

PubMed

Li, Xu; Xu, Qimin; Li, Bin; Song, Xianghui

2016-05-25

In this paper, we propose a novel positioning solution for land vehicles which is highly reliable and cost-efficient. The proposed positioning system fuses information from the MEMS-based reduced inertial sensor system (RISS) which consists of one vertical gyroscope and two horizontal accelerometers, low-cost GPS, and supplementary sensors and sources. First, pitch and roll angle are accurately estimated based on a vehicle kinematic model. Meanwhile, the negative effect of the uncertain nonlinear drift of MEMS inertial sensors is eliminated by an H∞ filter. Further, a distributed-dual-H∞ filtering (DDHF) mechanism is adopted to address the uncertain nonlinear drift of the MEMS-RISS and make full use of the supplementary sensors and sources. The DDHF is composed of a main H∞ filter (MHF) and an auxiliary H∞ filter (AHF). Finally, a generalized regression neural network (GRNN) module with good approximation capability is specially designed for the MEMS-RISS. A hybrid methodology which combines the GRNN module and the AHF is utilized to compensate for RISS position errors during GPS outages. To verify the effectiveness of the proposed solution, road-test experiments with various scenarios were performed. The experimental results illustrate that the proposed system can achieve accurate and reliable positioning for land vehicles.

A Highly Reliable and Cost-Efficient Multi-Sensor System for Land Vehicle Positioning

PubMed Central

Li, Xu; Xu, Qimin; Li, Bin; Song, Xianghui

2016-01-01

In this paper, we propose a novel positioning solution for land vehicles which is highly reliable and cost-efficient. The proposed positioning system fuses information from the MEMS-based reduced inertial sensor system (RISS) which consists of one vertical gyroscope and two horizontal accelerometers, low-cost GPS, and supplementary sensors and sources. First, pitch and roll angle are accurately estimated based on a vehicle kinematic model. Meanwhile, the negative effect of the uncertain nonlinear drift of MEMS inertial sensors is eliminated by an H∞ filter. Further, a distributed-dual-H∞ filtering (DDHF) mechanism is adopted to address the uncertain nonlinear drift of the MEMS-RISS and make full use of the supplementary sensors and sources. The DDHF is composed of a main H∞ filter (MHF) and an auxiliary H∞ filter (AHF). Finally, a generalized regression neural network (GRNN) module with good approximation capability is specially designed for the MEMS-RISS. A hybrid methodology which combines the GRNN module and the AHF is utilized to compensate for RISS position errors during GPS outages. To verify the effectiveness of the proposed solution, road-test experiments with various scenarios were performed. The experimental results illustrate that the proposed system can achieve accurate and reliable positioning for land vehicles. PMID:27231917

Sampling strategies based on singular vectors for assimilated models in ocean forecasting systems

NASA Astrophysics Data System (ADS)

Fattorini, Maria; Brandini, Carlo; Ortolani, Alberto

2016-04-01

Meteorological and oceanographic models do need observations, not only as a ground truth element to verify the quality of the models, but also to keep model forecast error acceptable: through data assimilation techniques which merge measured and modelled data, natural divergence of numerical solutions from reality can be reduced / controlled and a more reliable solution - called analysis - is computed. Although this concept is valid in general, its application, especially in oceanography, raises many problems due to three main reasons: the difficulties that have ocean models in reaching an acceptable state of equilibrium, the high measurements cost and the difficulties in realizing them. The performances of the data assimilation procedures depend on the particular observation networks in use, well beyond the background quality and the used assimilation method. In this study we will present some results concerning the great impact of the dataset configuration, in particular measurements position, on the evaluation of the overall forecasting reliability of an ocean model. The aim consists in identifying operational criteria to support the design of marine observation networks at regional scale. In order to identify the observation network able to minimize the forecast error, a methodology based on Singular Vectors Decomposition of the tangent linear model is proposed. Such a method can give strong indications on the local error dynamics. In addition, for the purpose of avoiding redundancy of information contained in the data, a minimal distance among data positions has been chosen on the base of a spatial correlation analysis of the hydrodynamic fields under investigation. This methodology has been applied for the choice of data positions starting from simplified models, like an ideal double-gyre model and a quasi-geostrophic one. Model configurations and data assimilation are based on available ROMS routines, where a variational assimilation algorithm (4D-var) is included as part of the code These first applications have provided encouraging results in terms of increased predictability time and reduced forecast error, also improving the quality of the analysis used to recover the real circulation patterns from a first guess quite far from the real state.

A Descriptive, Multiyear Examination of Positive Behavior Support

ERIC Educational Resources Information Center

Dunlap, Glen; Carr, Edward G.; Horner, Robert H.; Koegel, Robert L.; Sailor, Wayne; Clarke, Shelley; Koegel, Lynn Kern; Albin, Richard W.; Vaughn, Bobbie J.; McLaughlin, Darlene Magito; James, Kim Mullen; Todd, Anne W.; Newton, J. Stephen; Lucyshyn, Joseph; Griggs, Peter; Bohanon, Hank; Choi, Jeong Hoon; Vismara, Laurie; Minjarez, Mendy Boettcher; Buschbacher, Pamelazita; Fox, Lise

2010-01-01

A major goal of positive behavior support (PBS) is to produce broad-based, long-term improvements in adaptive behavior; however, the empirical base, at present, is mainly composed of relatively short-term studies carried out in circumscribed contexts. Therefore, a need exists for reliable data that can inform the field regarding the comprehensive…

Dynamic MRI to quantify musculoskeletal motion: A systematic review of concurrent validity and reliability, and perspectives for evaluation of musculoskeletal disorders.

PubMed

Borotikar, Bhushan; Lempereur, Mathieu; Lelievre, Mathieu; Burdin, Valérie; Ben Salem, Douraied; Brochard, Sylvain

2017-01-01

To report evidence for the concurrent validity and reliability of dynamic MRI techniques to evaluate in vivo joint and muscle mechanics, and to propose recommendations for their use in the assessment of normal and impaired musculoskeletal function. The search was conducted on articles published in Web of science, PubMed, Scopus, Academic search Premier, and Cochrane Library between 1990 and August 2017. Studies that reported the concurrent validity and/or reliability of dynamic MRI techniques for in vivo evaluation of joint or muscle mechanics were included after assessment by two independent reviewers. Selected articles were assessed using an adapted quality assessment tool and a data extraction process. Results for concurrent validity and reliability were categorized as poor, moderate, or excellent. Twenty articles fulfilled the inclusion criteria with a mean quality assessment score of 66% (±10.4%). Concurrent validity and/or reliability of eight dynamic MRI techniques were reported, with the knee being the most evaluated joint (seven studies). Moderate to excellent concurrent validity and reliability were reported for seven out of eight dynamic MRI techniques. Cine phase contrast and real-time MRI appeared to be the most valid and reliable techniques to evaluate joint motion, and spin tag for muscle motion. Dynamic MRI techniques are promising for the in vivo evaluation of musculoskeletal mechanics; however results should be evaluated with caution since validity and reliability have not been determined for all joints and muscles, nor for many pathological conditions.

The Reliability of Anthropometric Measurements Used Preoperatively in Aesthetic Breast Surgery.

PubMed

Isaac, Kathryn V; Murphy, Blake D; Beber, Brett; Brown, Mitchell

2016-04-01

Patient outcomes in aesthetic breast surgery are highly dependent on breast measurements used in preoperative planning. The purpose of this study is to determine the reliability of anthropometric breast measurements. Four raters measured 28 women using 7 measurements: sternal notch to nipple distance (Sn-N), nipple to midline (N-M), nipple to inframammary-fold distance under maximal stretch (N-IMF), breast base width (BW), soft tissue pinch thickness of the upper pole (STPT:UP), STPT at the inframammary fold (STPT:IMF), and anterior pull skin stretch (APSS). Reliability was assessed using intra-class correlation coefficients (ICCs). Inter-rater reliability was excellent for Sn-N, N-M, and BW (ICC = 0.94, 0.90, and 0.76, respectively) and was good for N-IMF (ICC = 0.70). The STPT:UP, STPT:IMF, and APSS measurements were not reliable between raters (ICC < 0.2). Intra-rater reliability was excellent for Sn-N, N-M, and BW for all raters (all ICC > 0.75). The N-IMF intra-rater reliability was excellent in senior raters (ICC > 0.75) and good in junior raters (ICC > 0.6). The STPT:UP, STPT:IMF, and APSS measurements showed fair or poor reliability for most raters (ICC < 0.6). The Sn-N, N-M, and BW measurements are very reliable. Dynamic measurements including APSS, STPT:UP, and STUP:IMF are unreliable. N-IMF is the only reliable dynamic measurement, and its reliability improves with increasing clinical experience. The variable reliability of preoperative measurements must be considered in the planning of aesthetic breast surgery. 4 Diagnostic. © 2015 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com.

Surveys Assessing Students' Attitudes toward Statistics: A Systematic Review of Validity and Reliability

ERIC Educational Resources Information Center

Nolan, Meaghan M.; Beran, Tanya; Hecker, Kent G.

2012-01-01

Students with positive attitudes toward statistics are likely to show strong academic performance in statistics courses. Multiple surveys measuring students' attitudes toward statistics exist; however, a comparison of the validity and reliability of interpretations based on their scores is needed. A systematic review of relevant electronic…

The validity and reliability of a dynamic neuromuscular stabilization-heel sliding test for core stability.

PubMed

Cha, Young Joo; Lee, Jae Jin; Kim, Do Hyun; You, Joshua Sung H

2017-10-23

Core stabilization plays an important role in the regulation of postural stability. To overcome shortcomings associated with pain and severe core instability during conventional core stabilization tests, we recently developed the dynamic neuromuscular stabilization-based heel sliding (DNS-HS) test. The purpose of this study was to establish the criterion validity and test-retest reliability of the novel DNS-HS test. Twenty young adults with core instability completed both the bilateral straight leg lowering test (BSLLT) and DNS-HS test for the criterion validity study and repeated the DNS-HS test for the test-retest reliability study. Criterion validity was determined by comparing hip joint angle data that were obtained from BSLLT and DNS-HS measures. The test-retest reliability was determined by comparing hip joint angle data. Criterion validity was (ICC2,3) = 0.700 (p< 0.05), suggesting a good relationship between the two core stability measures. Test-retest reliability was (ICC3,3) = 0.953 (p< 0.05), indicating excellent consistency between the repeated DNS-HS measurements. Criterion validity data demonstrated a good relationship between the gold standard BSLLT and DNS-HS core stability measures. Test-retest reliability data suggests that DNS-HS core stability was a reliable test for core stability. Clinically, the DNS-HS test is useful to objectively quantify core instability and allow early detection and evaluation.

INTRA-RATER RELIABILITY OF THE MULTIPLE SINGLE-LEG HOP-STABILIZATION TEST AND RELATIONSHIPS WITH AGE, LEG DOMINANCE AND TRAINING.

PubMed

Sawle, Leanne; Freeman, Jennifer; Marsden, Jonathan

2017-04-01

Balance is a complex construct, affected by multiple components such as strength and co-ordination. However, whilst assessing an athlete's dynamic balance is an important part of clinical examination, there is no gold standard measure. The multiple single-leg hop-stabilization test is a functional test which may offer a method of evaluating the dynamic attributes of balance, but it needs to show adequate intra-tester reliability. The purpose of this study was to assess the intra-rater reliability of a dynamic balance test, the multiple single-leg hop-stabilization test on the dominant and non-dominant legs. Intra-rater reliability study. Fifteen active participants were tested twice with a 10-minute break between tests. The outcome measure was the multiple single-leg hop-stabilization test score, based on a clinically assessed numerical scoring system. Results were analysed using an Intraclass Correlations Coefficient (ICC 2,1 ) and Bland-Altman plots. Regression analyses explored relationships between test scores, leg dominance, age and training (an alpha level of p = 0.05 was selected). ICCs for intra-rater reliability were 0.85 for the dominant and non-dominant legs (confidence intervals = 0.62-0.95 and 0.61-0.95 respectively). Bland-Altman plots showed scores within two standard deviations. A significant correlation was observed between the dominant and non-dominant leg on balance scores (R 2 =0.49, p<0.05), and better balance was associated with younger participants in their non-dominant leg (R 2 =0.28, p<0.05) and their dominant leg (R 2 =0.39, p<0.05), and a higher number of hours spent training for the non-dominant leg R 2 =0.37, p<0.05). The multiple single-leg hop-stabilisation test demonstrated strong intra-tester reliability with active participants. Younger participants who trained more, have better balance scores. This test may be a useful measure for evaluating the dynamic attributes of balance. 3.

Self-esteem among nursing assistants: reliability and validity of the Rosenberg Self-Esteem Scale.

PubMed

McMullen, Tara; Resnick, Barbara

2013-01-01

To establish the reliability and validity of the Rosenberg Self-Esteem Scale (RSES) when used with nursing assistants (NAs). Testing the RSES used baseline data from a randomized controlled trial testing the Res-Care Intervention. Female NAs were recruited from nursing homes (n = 508). Validity testing for the positive and negative subscales of the RSES was based on confirmatory factor analysis (CFA) using structural equation modeling and Rasch analysis. Estimates of reliability were based on Rasch analysis and the person separation index. Evidence supports the reliability and validity of the RSES in NAs although we recommend minor revisions to the measure for subsequent use. Establishing reliable and valid measures of self-esteem in NAs will facilitate testing of interventions to strengthen workplace self-esteem, job satisfaction, and retention.

Validation of a Statistical Methodology for Extracting Vegetation Feedbacks: Focus on North African Ecosystems in the Community Earth System Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Yan; Notaro, Michael; Wang, Fuyao

Generalized equilibrium feedback assessment (GEFA) is a potentially valuable multivariate statistical tool for extracting vegetation feedbacks to the atmosphere in either observations or coupled Earth system models. The reliability of GEFA at capturing the terrestrial impacts on regional climate is demonstrated in this paper using the National Center for Atmospheric Research Community Earth System Model (CESM), with focus on North Africa. The feedback is assessed statistically by applying GEFA to output from a fully coupled control run. To reduce the sampling error caused by short data records, the traditional or full GEFA is refined through stepwise GEFA by dropping unimportantmore » forcings. Two ensembles of dynamical experiments are developed for the Sahel or West African monsoon region against which GEFA-based vegetation feedbacks are evaluated. In these dynamical experiments, regional leaf area index (LAI) is modified either alone or in conjunction with soil moisture, with the latter runs motivated by strong regional soil moisture–LAI coupling. Stepwise GEFA boasts higher consistency between statistically and dynamically assessed atmospheric responses to land surface anomalies than full GEFA, especially with short data records. GEFA-based atmospheric responses are more consistent with the coupled soil moisture–LAI experiments, indicating that GEFA is assessing the combined impacts of coupled vegetation and soil moisture. Finally, both the statistical and dynamical assessments reveal a negative vegetation–rainfall feedback in the Sahel associated with an atmospheric stability mechanism in CESM versus a weaker positive feedback in the West African monsoon region associated with a moisture recycling mechanism in CESM.« less

Validation of a Statistical Methodology for Extracting Vegetation Feedbacks: Focus on North African Ecosystems in the Community Earth System Model

DOE PAGES

Yu, Yan; Notaro, Michael; Wang, Fuyao; ...

2018-02-05

Generalized equilibrium feedback assessment (GEFA) is a potentially valuable multivariate statistical tool for extracting vegetation feedbacks to the atmosphere in either observations or coupled Earth system models. The reliability of GEFA at capturing the terrestrial impacts on regional climate is demonstrated in this paper using the National Center for Atmospheric Research Community Earth System Model (CESM), with focus on North Africa. The feedback is assessed statistically by applying GEFA to output from a fully coupled control run. To reduce the sampling error caused by short data records, the traditional or full GEFA is refined through stepwise GEFA by dropping unimportantmore » forcings. Two ensembles of dynamical experiments are developed for the Sahel or West African monsoon region against which GEFA-based vegetation feedbacks are evaluated. In these dynamical experiments, regional leaf area index (LAI) is modified either alone or in conjunction with soil moisture, with the latter runs motivated by strong regional soil moisture–LAI coupling. Stepwise GEFA boasts higher consistency between statistically and dynamically assessed atmospheric responses to land surface anomalies than full GEFA, especially with short data records. GEFA-based atmospheric responses are more consistent with the coupled soil moisture–LAI experiments, indicating that GEFA is assessing the combined impacts of coupled vegetation and soil moisture. Finally, both the statistical and dynamical assessments reveal a negative vegetation–rainfall feedback in the Sahel associated with an atmospheric stability mechanism in CESM versus a weaker positive feedback in the West African monsoon region associated with a moisture recycling mechanism in CESM.« less

New Quality Control Algorithm Based on GNSS Sensing Data for a Bridge Health Monitoring System

PubMed Central

Lee, Jae Kang; Lee, Jae One; Kim, Jung Ok

2016-01-01

This research introduces an improvement plan for the reliability of Global Navigation Satellite System (GNSS) positioning solutions. It should be considered the most suitable methodology in terms of the adjustment and positioning of GNSS in order to maximize the utilization of GNSS applications. Though various studies have been conducted with regards to Bridge Health Monitoring System (BHMS) based on GNSS, the outliers which depend on the signal reception environment could not be considered until now. Since these outliers may be connected to GNSS data collected from major bridge members, which can reduce the reliability of a whole monitoring system through the delivery of false information, they should be detected and eliminated in the previous adjustment stage. In this investigation, the Detection, Identification, Adaptation (DIA) technique was applied and implemented through an algorithm. Moreover, it can be directly applied to GNSS data collected from long span cable stayed bridges and most of outliers were efficiently detected and eliminated simultaneously. By these effects, the reliability of GNSS should be enormously improved. Improvement on GNSS positioning accuracy is directly linked to the safety of bridges itself, and at the same time, the reliability of monitoring systems in terms of the system operation can also be increased. PMID:27240375

New Quality Control Algorithm Based on GNSS Sensing Data for a Bridge Health Monitoring System.

PubMed

Lee, Jae Kang; Lee, Jae One; Kim, Jung Ok

2016-05-27

This research introduces an improvement plan for the reliability of Global Navigation Satellite System (GNSS) positioning solutions. It should be considered the most suitable methodology in terms of the adjustment and positioning of GNSS in order to maximize the utilization of GNSS applications. Though various studies have been conducted with regards to Bridge Health Monitoring System (BHMS) based on GNSS, the outliers which depend on the signal reception environment could not be considered until now. Since these outliers may be connected to GNSS data collected from major bridge members, which can reduce the reliability of a whole monitoring system through the delivery of false information, they should be detected and eliminated in the previous adjustment stage. In this investigation, the Detection, Identification, Adaptation (DIA) technique was applied and implemented through an algorithm. Moreover, it can be directly applied to GNSS data collected from long span cable stayed bridges and most of outliers were efficiently detected and eliminated simultaneously. By these effects, the reliability of GNSS should be enormously improved. Improvement on GNSS positioning accuracy is directly linked to the safety of bridges itself, and at the same time, the reliability of monitoring systems in terms of the system operation can also be increased.

Node Self-Deployment Algorithm Based on an Uneven Cluster with Radius Adjusting for Underwater Sensor Networks

PubMed Central

Jiang, Peng; Xu, Yiming; Wu, Feng

2016-01-01

Existing move-restricted node self-deployment algorithms are based on a fixed node communication radius, evaluate the performance based on network coverage or the connectivity rate and do not consider the number of nodes near the sink node and the energy consumption distribution of the network topology, thereby degrading network reliability and the energy consumption balance. Therefore, we propose a distributed underwater node self-deployment algorithm. First, each node begins the uneven clustering based on the distance on the water surface. Each cluster head node selects its next-hop node to synchronously construct a connected path to the sink node. Second, the cluster head node adjusts its depth while maintaining the layout formed by the uneven clustering and then adjusts the positions of in-cluster nodes. The algorithm originally considers the network reliability and energy consumption balance during node deployment and considers the coverage redundancy rate of all positions that a node may reach during the node position adjustment. Simulation results show, compared to the connected dominating set (CDS) based depth computation algorithm, that the proposed algorithm can increase the number of the nodes near the sink node and improve network reliability while guaranteeing the network connectivity rate. Moreover, it can balance energy consumption during network operation, further improve network coverage rate and reduce energy consumption. PMID:26784193

Geo-Referenced Dynamic Pushbroom Stereo Mosaics for 3D and Moving Target Extraction - A New Geometric Approach

DTIC Science & Technology

2009-12-01

facilitating reliable stereo matching, occlusion handling, accurate 3D reconstruction and robust moving target detection . We use the fact that all the...a moving platform, we will have to naturally and effectively handle obvious motion parallax and object occlusions in order to be able to detect ...facilitating reliable stereo matching, occlusion handling, accurate 3D reconstruction and robust moving target detection . Based on the above two

Step-Down Test Assessment of Postural Stability in Patients With Chronic Ankle Instability.

PubMed

Bolt, Doris; Giger, René; Wirth, Stefan; Swanenburg, Jaap

2018-01-23

The underlying mechanism in 27% of ankle sprains is a fall while navigating stairs. Therefore, the step-down test (SDT) may be useful to investigate dynamic postural stability deficits in individuals with chronic ankle instability (CAI). To investigate the test-retest reliability and validity of the forward and lateral SDT protocol between individuals with CAI and uninjured controls. Test-retest study. University hospital. A total of 46  individuals, 23 with CAI and 23 uninjured controls. Time to stabilization of the forward and lateral SDT. The absolute reliability (SEM = 0.04-0.12 s; SDD = 0.11-0.33 s) of the SDT protocol was acceptable, whereas the relative reliability (ICC 3 , k = 0.12-0.63) and discriminant validity (P = .42-.99; AUC = 0.50-0.57) were not. The SDT appears to not be challenging enough to detect dynamic postural stability differences between individuals with and without CAI. However, the SDT may be capable of measuring change over time based on its good absolute reliability.

IMU-based online kinematic calibration of robot manipulator.

PubMed

Du, Guanglong; Zhang, Ping

2013-01-01

Robot calibration is a useful diagnostic method for improving the positioning accuracy in robot production and maintenance. An online robot self-calibration method based on inertial measurement unit (IMU) is presented in this paper. The method requires that the IMU is rigidly attached to the robot manipulator, which makes it possible to obtain the orientation of the manipulator with the orientation of the IMU in real time. This paper proposed an efficient approach which incorporates Factored Quaternion Algorithm (FQA) and Kalman Filter (KF) to estimate the orientation of the IMU. Then, an Extended Kalman Filter (EKF) is used to estimate kinematic parameter errors. Using this proposed orientation estimation method will result in improved reliability and accuracy in determining the orientation of the manipulator. Compared with the existing vision-based self-calibration methods, the great advantage of this method is that it does not need the complex steps, such as camera calibration, images capture, and corner detection, which make the robot calibration procedure more autonomous in a dynamic manufacturing environment. Experimental studies on a GOOGOL GRB3016 robot show that this method has better accuracy, convenience, and effectiveness than vision-based methods.

The use of x-ray pulsar-based navigation method for interplanetary flight

NASA Astrophysics Data System (ADS)

Yang, Bo; Guo, Xingcan; Yang, Yong

2009-07-01

As interplanetary missions are increasingly complex, the existing unique mature interplanetary navigation method mainly based on radiometric tracking techniques of Deep Space Network can not meet the rising demands of autonomous real-time navigation. This paper studied the applications for interplanetary flights of a new navigation technology under rapid development-the X-ray pulsar-based navigation for spacecraft (XPNAV), and valued its performance with a computer simulation. The XPNAV is an excellent autonomous real-time navigation method, and can provide comprehensive navigation information, including position, velocity, attitude, attitude rate and time. In the paper the fundamental principles and time transformation of the XPNAV were analyzed, and then the Delta-correction XPNAV blending the vehicles' trajectory dynamics with the pulse time-of-arrival differences at nominal and estimated spacecraft locations within an Unscented Kalman Filter (UKF) was discussed with a background mission of Mars Pathfinder during the heliocentric transferring orbit. The XPNAV has an intractable problem of integer pulse phase cycle ambiguities similar to the GPS carrier phase navigation. This article innovatively proposed the non-ambiguity assumption approach based on an analysis of the search space array method to resolve pulse phase cycle ambiguities between the nominal position and estimated position of the spacecraft. The simulation results show that the search space array method are computationally intensive and require long processing time when the position errors are large, and the non-ambiguity assumption method can solve ambiguity problem quickly and reliably. It is deemed that autonomous real-time integrated navigation system of the XPNAV blending with DSN, celestial navigation, inertial navigation and so on will be the development direction of interplanetary flight navigation system in the future.

A reliability design method for a lithium-ion battery pack considering the thermal disequilibrium in electric vehicles

NASA Astrophysics Data System (ADS)

Xia, Quan; Wang, Zili; Ren, Yi; Sun, Bo; Yang, Dezhen; Feng, Qiang

2018-05-01

With the rapid development of lithium-ion battery technology in the electric vehicle (EV) industry, the lifetime of the battery cell increases substantially; however, the reliability of the battery pack is still inadequate. Because of the complexity of the battery pack, a reliability design method for a lithium-ion battery pack considering the thermal disequilibrium is proposed in this paper based on cell redundancy. Based on this method, a three-dimensional electric-thermal-flow-coupled model, a stochastic degradation model of cells under field dynamic conditions and a multi-state system reliability model of a battery pack are established. The relationships between the multi-physics coupling model, the degradation model and the system reliability model are first constructed to analyze the reliability of the battery pack and followed by analysis examples with different redundancy strategies. By comparing the reliability of battery packs of different redundant cell numbers and configurations, several conclusions for the redundancy strategy are obtained. More notably, the reliability does not monotonically increase with the number of redundant cells for the thermal disequilibrium effects. In this work, the reliability of a 6 × 5 parallel-series configuration is the optimal system structure. In addition, the effect of the cell arrangement and cooling conditions are investigated.

Dynamic SLA Negotiation in Autonomic Federated Environments

NASA Astrophysics Data System (ADS)

Rubach, Pawel; Sobolewski, Michael

Federated computing environments offer requestors the ability to dynamically invoke services offered by collaborating providers in the virtual service network. Without an efficient resource management that includes Dynamic SLA Negotiation, however, the assignment of providers to customer's requests cannot be optimized and cannot offer high reliability without relevant SLA guarantees. We propose a new SLA-based SERViceable Metacomputing Environment (SERVME) capable of matching providers based on QoS requirements and performing autonomic provisioning and deprovisioning of services according to dynamic requestor needs. This paper presents the SLA negotiation process that includes on-demand provisioning and uses an object-oriented SLA model for large-scale service-oriented systems supported by SERVME. An initial reference implementation in the SORCER environment is also described.

Non-invasive prediction of recurrence in bladder cancer by detecting somatic TERT promoter mutations in urine.

PubMed

Descotes, Françoise; Kara, Norelyakin; Decaussin-Petrucci, Myriam; Piaton, Eric; Geiguer, Florence; Rodriguez-Lafrasse, Claire; Terrier, Jean E; Lopez, Jonathan; Ruffion, Alain

2017-08-08

Urothelial bladder cancer (UBC) is characterised by a high risk of recurrence. Patient monitoring is currently based on iterative cystoscopy and on urine cytology with low sensitivity in non-muscle-invasive bladder cancer (NMIBC). Telomerase reverse transcriptase (TERT) is frequently reactivated in UBC by promoter mutations. We studied whether detection of TERT mutation in urine could be a predictor of UBC recurrence and compared this to cytology/cystoscopy for patient follow-up. A total of 348 patients treated by transurethral bladder resection for UBC were included together with 167 control patients. Overall sensitivity was 80.5% and specificity 89.8%, and was not greatly impacted by inflammation or infection. TERT remaining positive after initial surgery was associated with residual carcinoma in situ. TERT in urine was a reliable and dynamic predictor of recurrence in NMIBC (P<0.0001). In univariate analysis, TERT positive-status after initial surgery increased risk of recurrence by 5.34-fold (P=0.0004). TERT positive-status was still associated with recurrence in the subset of patients with negative cystoscopy (P=0.034). TERT mutations in urine might be helpful for early detection of recurrence in UBC, especially in NMIBC.

Mapping the ecological networks of microbial communities.

PubMed

Xiao, Yandong; Angulo, Marco Tulio; Friedman, Jonathan; Waldor, Matthew K; Weiss, Scott T; Liu, Yang-Yu

2017-12-11

Mapping the ecological networks of microbial communities is a necessary step toward understanding their assembly rules and predicting their temporal behavior. However, existing methods require assuming a particular population dynamics model, which is not known a priori. Moreover, those methods require fitting longitudinal abundance data, which are often not informative enough for reliable inference. To overcome these limitations, here we develop a new method based on steady-state abundance data. Our method can infer the network topology and inter-taxa interaction types without assuming any particular population dynamics model. Additionally, when the population dynamics is assumed to follow the classic Generalized Lotka-Volterra model, our method can infer the inter-taxa interaction strengths and intrinsic growth rates. We systematically validate our method using simulated data, and then apply it to four experimental data sets. Our method represents a key step towards reliable modeling of complex, real-world microbial communities, such as the human gut microbiota.

A novel dynamic flow immunochromatographic test (DFICT) using gold nanoparticles for the serological detection of Toxoplasma gondii infection in dogs and cats.

PubMed

Jiang, Wei; Liu, Yingchun; Chen, Yongjun; Yang, Qiufeng; Chun, Peter; Yao, Kailing; Han, Xiangan; Wang, Shaohui; Yu, Shengqing; Liu, Yongjie; Wang, Quan

2015-10-15

A novel dynamic flow immunochromatographic test (DFICT) is proposed for rapid assay utilizing Toxoplasma gondii as a model. The test is based on a proprietary technology that combines the principles of immunochromatography and fluid dynamics. Gold nanoparticles conjugated to staphylococcal protein A (SPA) were prepared in liquid form and used as signal vehicles. T. gondii-specific recombinant antigens and SPA were sprayed onto a nitrocellulose membrane in strips at positions designated as T and C, respectively. The DFICT is performed by applying a 100 µL aliquot of liquid gold-SPA conjugate to the reagent hole and a 5 μL aliquot of serum sample to the sample hole. The results were observable within 5 min by the naked eye. The lowest detectable limit of the assay was determined as the highest dilution (1:320) of positive serum. No cross-reaction of the antibodies with other related canine or feline pathogens was observed. The DFICT can be stored for 12 months at 4°C or 6 months with no loss of sensitivity or specificity. A high degree of consistency was observed between the DFICT and the standard ELISA kit, supporting the reliability of the novel test strip. The introduction of a liquid gold nanoparticle conjugate reagent provides this method with several attractive characteristics, such as ease of manufacture, low sample volume requirements, high selectivity and high efficiency. This method opens a novel pathway for rapid diagnostic screening and field analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

Dynamic MRI to quantify musculoskeletal motion: A systematic review of concurrent validity and reliability, and perspectives for evaluation of musculoskeletal disorders

PubMed Central

Lempereur, Mathieu; Lelievre, Mathieu; Burdin, Valérie; Ben Salem, Douraied; Brochard, Sylvain

2017-01-01

Purpose To report evidence for the concurrent validity and reliability of dynamic MRI techniques to evaluate in vivo joint and muscle mechanics, and to propose recommendations for their use in the assessment of normal and impaired musculoskeletal function. Materials and methods The search was conducted on articles published in Web of science, PubMed, Scopus, Academic search Premier, and Cochrane Library between 1990 and August 2017. Studies that reported the concurrent validity and/or reliability of dynamic MRI techniques for in vivo evaluation of joint or muscle mechanics were included after assessment by two independent reviewers. Selected articles were assessed using an adapted quality assessment tool and a data extraction process. Results for concurrent validity and reliability were categorized as poor, moderate, or excellent. Results Twenty articles fulfilled the inclusion criteria with a mean quality assessment score of 66% (±10.4%). Concurrent validity and/or reliability of eight dynamic MRI techniques were reported, with the knee being the most evaluated joint (seven studies). Moderate to excellent concurrent validity and reliability were reported for seven out of eight dynamic MRI techniques. Cine phase contrast and real-time MRI appeared to be the most valid and reliable techniques to evaluate joint motion, and spin tag for muscle motion. Conclusion Dynamic MRI techniques are promising for the in vivo evaluation of musculoskeletal mechanics; however results should be evaluated with caution since validity and reliability have not been determined for all joints and muscles, nor for many pathological conditions. PMID:29232401

Multi-GNSS high-rate RTK, PPP and novel direct phase observation processing method: application to precise dynamic displacement detection

NASA Astrophysics Data System (ADS)

Paziewski, Jacek; Sieradzki, Rafal; Baryla, Radoslaw

2018-03-01

This paper provides the methodology and performance assessment of multi-GNSS signal processing for the detection of small-scale high-rate dynamic displacements. For this purpose, we used methods of relative (RTK) and absolute positioning (PPP), and a novel direct signal processing approach. The first two methods are recognized as providing accurate information on position in many navigation and surveying applications. The latter is an innovative method for dynamic displacement determination with the use of GNSS phase signal processing. This method is based on the developed functional model with parametrized epoch-wise topocentric relative coordinates derived from filtered GNSS observations. Current regular kinematic PPP positioning, as well as medium/long range RTK, may not offer coordinate estimates with subcentimeter precision. Thus, extended processing strategies of absolute and relative GNSS positioning have been developed and applied for displacement detection. The study also aimed to comparatively analyze the developed methods as well as to analyze the impact of combined GPS and BDS processing and the dependence of the results of the relative methods on the baseline length. All the methods were implemented with in-house developed software allowing for high-rate precise GNSS positioning and signal processing. The phase and pseudorange observations collected with a rate of 50 Hz during the field test served as the experiment’s data set. The displacements at the rover station were triggered in the horizontal plane using a device which was designed and constructed to ensure a periodic motion of GNSS antenna with an amplitude of ~3 cm and a frequency of ~4.5 Hz. Finally, a medium range RTK, PPP, and direct phase observation processing method demonstrated the capability of providing reliable and consistent results with the precision of the determined dynamic displacements at the millimeter level. Specifically, the research shows that the standard deviation of the displacement residuals obtained as the difference between a benchmark-ultra-short baseline RTK solution and selected scenarios ranged between 1.1 and 3.4 mm. At the same time, the differences in the mean amplitude of the oscillations derived from the established scenarios did not exceed 1.3 mm, whereas the frequency of the motion detected with the use of Fourier transformation was the same.

Pectus excavatum postsurgical outcome based on preoperative soft body dynamics simulation

NASA Astrophysics Data System (ADS)

Moreira, Antonio H. J.; Rodrigues, Pedro L.; Fonseca, Jaime; Pinho, A. C. M.; Rodrigues, Nuno F.; Correia-Pinto, Jorge; Vilaça, João L.

2012-02-01

Pectus excavatum is the most common congenital deformity of the anterior chest wall, in which an abnormal formation of the rib cage gives the chest a caved-in or sunken appearance. Today, the surgical correction of this deformity is carried out in children and adults through Nuss technic, which consists in the placement of a prosthetic bar under the sternum and over the ribs. Although this technique has been shown to be safe and reliable, not all patients have achieved adequate cosmetic outcome. This often leads to psychological problems and social stress, before and after the surgical correction. This paper targets this particular problem by presenting a method to predict the patient surgical outcome based on pre-surgical imagiologic information and chest skin dynamic modulation. The proposed approach uses the patient pre-surgical thoracic CT scan and anatomical-surgical references to perform a 3D segmentation of the left ribs, right ribs, sternum and skin. The technique encompasses three steps: a) approximation of the cartilages, between the ribs and the sternum, trough b-spline interpolation; b) a volumetric mass spring model that connects two layers - inner skin layer based on the outer pleura contour and the outer surface skin; and c) displacement of the sternum according to the prosthetic bar position. A dynamic model of the skin around the chest wall region was generated, capable of simulating the effect of the movement of the prosthetic bar along the sternum. The results were compared and validated with patient postsurgical skin surface acquired with Polhemus FastSCAN system.

Colon Stem Cell and Crypt Dynamics Exposed by Cell Lineage Reconstruction

PubMed Central

Itzkovitz, Shalev; Elbaz, Judith; Maruvka, Yosef E.; Segev, Elad; Shlush, Liran I.; Dekel, Nava; Shapiro, Ehud

2011-01-01

Stem cell dynamics in vivo are often being studied by lineage tracing methods. Our laboratory has previously developed a retrospective method for reconstructing cell lineage trees from somatic mutations accumulated in microsatellites. This method was applied here to explore different aspects of stem cell dynamics in the mouse colon without the use of stem cell markers. We first demonstrated the reliability of our method for the study of stem cells by confirming previously established facts, and then we addressed open questions. Our findings confirmed that colon crypts are monoclonal and that, throughout adulthood, the process of monoclonal conversion plays a major role in the maintenance of crypts. The absence of immortal strand mechanism in crypts stem cells was validated by the age-dependent accumulation of microsatellite mutations. In addition, we confirmed the positive correlation between physical and lineage proximity of crypts, by showing that the colon is separated into small domains that share a common ancestor. We gained new data demonstrating that colon epithelium is clustered separately from hematopoietic and other cell types, indicating that the colon is constituted of few progenitors and ruling out significant renewal of colonic epithelium from hematopoietic cells during adulthood. Overall, our study demonstrates the reliability of cell lineage reconstruction for the study of stem cell dynamics, and it further addresses open questions in colon stem cells. In addition, this method can be applied to study stem cell dynamics in other systems. PMID:21829376

Analysis of generic reentry vehicle flight dynamics

NASA Astrophysics Data System (ADS)

Metsker, Yu.; Weinand, K.; Geulen, G.; Haidn, O. J.

2018-06-01

The knowledge of reentry vehicles (RV) flight characteristics regarding geometrical shape, dimensions, and mechanical properties is essential for precise prediction of their flight trajectory, impact point, and possible deviations according to simulation uncertainties. The flight characteristic estimations of existing RV require both body dimensions and mechanical properties of the objects. Due to comparatively simple and reliable methods of specifying the vehicle outer dimensions, e. g., photos and videomaterials, the estimation of mechanical properties is a subject of higher uncertainties. Within this study, a generic medium range ballistic missile (MRBM) RV was examined for several modifications such as center of gravity (CoG) position, weight moment of inertia, and initial reentry flight states. Combinations of these variables with constant aerodynamic properties for maximal lateral accelerations will be determined. Basing on these, potential evasion maneuver capabilities of the RV will be described.

A self-assembled nanoscale robotic arm controlled by electric fields

NASA Astrophysics Data System (ADS)

Kopperger, Enzo; List, Jonathan; Madhira, Sushi; Rothfischer, Florian; Lamb, Don C.; Simmel, Friedrich C.

2018-01-01

The use of dynamic, self-assembled DNA nanostructures in the context of nanorobotics requires fast and reliable actuation mechanisms. We therefore created a 55-nanometer–by–55-nanometer DNA-based molecular platform with an integrated robotic arm of length 25 nanometers, which can be extended to more than 400 nanometers and actuated with externally applied electrical fields. Precise, computer-controlled switching of the arm between arbitrary positions on the platform can be achieved within milliseconds, as demonstrated with single-pair Förster resonance energy transfer experiments and fluorescence microscopy. The arm can be used for electrically driven transport of molecules or nanoparticles over tens of nanometers, which is useful for the control of photonic and plasmonic processes. Application of piconewton forces by the robot arm is demonstrated in force-induced DNA duplex melting experiments.

Reliability Evaluation of Machine Center Components Based on Cascading Failure Analysis

NASA Astrophysics Data System (ADS)

Zhang, Ying-Zhi; Liu, Jin-Tong; Shen, Gui-Xiang; Long, Zhe; Sun, Shu-Guang

2017-07-01

In order to rectify the problems that the component reliability model exhibits deviation, and the evaluation result is low due to the overlook of failure propagation in traditional reliability evaluation of machine center components, a new reliability evaluation method based on cascading failure analysis and the failure influenced degree assessment is proposed. A direct graph model of cascading failure among components is established according to cascading failure mechanism analysis and graph theory. The failure influenced degrees of the system components are assessed by the adjacency matrix and its transposition, combined with the Pagerank algorithm. Based on the comprehensive failure probability function and total probability formula, the inherent failure probability function is determined to realize the reliability evaluation of the system components. Finally, the method is applied to a machine center, it shows the following: 1) The reliability evaluation values of the proposed method are at least 2.5% higher than those of the traditional method; 2) The difference between the comprehensive and inherent reliability of the system component presents a positive correlation with the failure influenced degree of the system component, which provides a theoretical basis for reliability allocation of machine center system.

Benchmarking novel approaches for modelling species range dynamics

PubMed Central

Zurell, Damaris; Thuiller, Wilfried; Pagel, Jörn; Cabral, Juliano S; Münkemüller, Tamara; Gravel, Dominique; Dullinger, Stefan; Normand, Signe; Schiffers, Katja H.; Moore, Kara A.; Zimmermann, Niklaus E.

2016-01-01

Increasing biodiversity loss due to climate change is one of the most vital challenges of the 21st century. To anticipate and mitigate biodiversity loss, models are needed that reliably project species’ range dynamics and extinction risks. Recently, several new approaches to model range dynamics have been developed to supplement correlative species distribution models (SDMs), but applications clearly lag behind model development. Indeed, no comparative analysis has been performed to evaluate their performance. Here, we build on process-based, simulated data for benchmarking five range (dynamic) models of varying complexity including classical SDMs, SDMs coupled with simple dispersal or more complex population dynamic models (SDM hybrids), and a hierarchical Bayesian process-based dynamic range model (DRM). We specifically test the effects of demographic and community processes on model predictive performance. Under current climate, DRMs performed best, although only marginally. Under climate change, predictive performance varied considerably, with no clear winners. Yet, all range dynamic models improved predictions under climate change substantially compared to purely correlative SDMs, and the population dynamic models also predicted reasonable extinction risks for most scenarios. When benchmarking data were simulated with more complex demographic and community processes, simple SDM hybrids including only dispersal often proved most reliable. Finally, we found that structural decisions during model building can have great impact on model accuracy, but prior system knowledge on important processes can reduce these uncertainties considerably. Our results reassure the clear merit in using dynamic approaches for modelling species’ response to climate change but also emphasise several needs for further model and data improvement. We propose and discuss perspectives for improving range projections through combination of multiple models and for making these approaches operational for large numbers of species. PMID:26872305

Benchmarking novel approaches for modelling species range dynamics.

PubMed

Zurell, Damaris; Thuiller, Wilfried; Pagel, Jörn; Cabral, Juliano S; Münkemüller, Tamara; Gravel, Dominique; Dullinger, Stefan; Normand, Signe; Schiffers, Katja H; Moore, Kara A; Zimmermann, Niklaus E

2016-08-01

Increasing biodiversity loss due to climate change is one of the most vital challenges of the 21st century. To anticipate and mitigate biodiversity loss, models are needed that reliably project species' range dynamics and extinction risks. Recently, several new approaches to model range dynamics have been developed to supplement correlative species distribution models (SDMs), but applications clearly lag behind model development. Indeed, no comparative analysis has been performed to evaluate their performance. Here, we build on process-based, simulated data for benchmarking five range (dynamic) models of varying complexity including classical SDMs, SDMs coupled with simple dispersal or more complex population dynamic models (SDM hybrids), and a hierarchical Bayesian process-based dynamic range model (DRM). We specifically test the effects of demographic and community processes on model predictive performance. Under current climate, DRMs performed best, although only marginally. Under climate change, predictive performance varied considerably, with no clear winners. Yet, all range dynamic models improved predictions under climate change substantially compared to purely correlative SDMs, and the population dynamic models also predicted reasonable extinction risks for most scenarios. When benchmarking data were simulated with more complex demographic and community processes, simple SDM hybrids including only dispersal often proved most reliable. Finally, we found that structural decisions during model building can have great impact on model accuracy, but prior system knowledge on important processes can reduce these uncertainties considerably. Our results reassure the clear merit in using dynamic approaches for modelling species' response to climate change but also emphasize several needs for further model and data improvement. We propose and discuss perspectives for improving range projections through combination of multiple models and for making these approaches operational for large numbers of species. © 2016 John Wiley & Sons Ltd.

Reliable resonance assignments of selected residues of proteins with known structure based on empirical NMR chemical shift prediction

NASA Astrophysics Data System (ADS)

Li, Da-Wei; Meng, Dan; Brüschweiler, Rafael

2015-05-01

A robust NMR resonance assignment method is introduced for proteins whose 3D structure has previously been determined by X-ray crystallography. The goal of the method is to obtain a subset of correct assignments from a parsimonious set of 3D NMR experiments of 15N, 13C labeled proteins. Chemical shifts of sequential residue pairs are predicted from static protein structures using PPM_One, which are then compared with the corresponding experimental shifts. Globally optimized weighted matching identifies the assignments that are robust with respect to small changes in NMR cross-peak positions. The method, termed PASSPORT, is demonstrated for 4 proteins with 100-250 amino acids using 3D NHCA and a 3D CBCA(CO)NH experiments as input producing correct assignments with high reliability for 22% of the residues. The method, which works best for Gly, Ala, Ser, and Thr residues, provides assignments that serve as anchor points for additional assignments by both manual and semi-automated methods or they can be directly used for further studies, e.g. on ligand binding, protein dynamics, or post-translational modification, such as phosphorylation.

Reliable Resonance Assignments of Selected Residues of Proteins with Known Structure Based on Empirical NMR Chemical Shift Prediction

PubMed Central

Li, Da-Wei; Meng, Dan; Brüschweiler, Rafael

2015-01-01

A robust NMR resonance assignment method is introduced for proteins whose 3D structure has previously been determined by X-ray crystallography. The goal of the method is to obtain a subset of correct assignments from a parsimonious set of 3D NMR experiments of 15N, 13C labeled proteins. Chemical shifts of sequential residue pairs are predicted from static protein structures using PPM_One, which are then compared with the corresponding experimental shifts. Globally optimized weighted matching identifies the assignments that are robust with respect to small changes in NMR cross-peak positions. The method, termed PASSPORT, is demonstrated for 4 proteins with 100 – 250 amino acids using 3D NHCA and a 3D CBCA(CO)NH experiments as input producing correct assignments with high reliability for 22% of the residues. The method, which works best for Gly, Ala, Ser, and Thr residues, provides assignments that serve as anchor points for additional assignments by both manual and semi-automated methods or they can be directly used for further studies, e.g. on ligand binding, protein dynamics, or post-translational modification, such as phosphorylation. PMID:25863893

Toward a greater understanding of the emotional dynamics of the mortality salience manipulation: revisiting the "affect-free" claim of terror management research.

PubMed

Lambert, Alan J; Eadeh, Fade R; Peak, Stephanie A; Scherer, Laura D; Schott, John Paul; Slochower, John M

2014-05-01

The experimental manipulation of mortality salience (MS) represents one of the most widely used methodological procedures in social psychology, having been employed by terror management researchers in hundreds of studies over the last 20 years. One of the more provocative conclusions regarding this task is that it does not produce any reliable changes in self-reported affect, a view that we refer to as the affect-free claim. After reviewing 336 published studies that used the standard version of the MS task, we suggest that the evidence on which this claim is based may be less definitive than is commonly supposed. Moreover, we propose that the MS manipulation can, in fact, produce significant and meaningful changes in affect once one employs the appropriate measures and experimental design. In support of this position, we report 4 experiments, each of which demonstrates reliable activation of negative affect, especially with respect to fear-/terror-related sentiments. We discuss the implications of our findings for terror management theory as well as for research and theory on the measurement of mood and emotion.

Long-term recording and automatic analysis of cough using filtered acoustic signals and movements on static charge sensitive bed.

PubMed

Salmi, T; Sovijärvi, A R; Brander, P; Piirilä, P

1988-11-01

Reliable long-term assessment of cough is necessary in many clinical and scientific settings. A new method for long-term recording and automatic analysis of cough is presented. The method is based on simultaneous recording of two independent signals: high-pass filtered cough sounds and cough-induced fast movements of the body. The acoustic signals are recorded with a dynamic microphone in the acoustic focus of a glass fiber paraboloid mirror. Body movements are recorded with a static charge-sensitive bed located under an ordinary plastic foam mattress. The patient can be studied lying or sitting with no transducers or electrodes attached. A microcomputer is used for sampling of signals, detection of cough, statistical analyses, and on-line printing of results. The method was validated in seven adult patients with a total of 809 spontaneous cough events, using clinical observation as a reference. The sensitivity of the method to detect cough was 99.0 percent, and the positive predictivity was 98.1 percent. The system ignored speaking and snoring. The method provides a convenient means of reliable long-term follow-up of cough in clinical work and research.

Bayesian parameter estimation for stochastic models of biological cell migration

NASA Astrophysics Data System (ADS)

Dieterich, Peter; Preuss, Roland

2013-08-01

Cell migration plays an essential role under many physiological and patho-physiological conditions. It is of major importance during embryonic development and wound healing. In contrast, it also generates negative effects during inflammation processes, the transmigration of tumors or the formation of metastases. Thus, a reliable quantification and characterization of cell paths could give insight into the dynamics of these processes. Typically stochastic models are applied where parameters are extracted by fitting models to the so-called mean square displacement of the observed cell group. We show that this approach has several disadvantages and problems. Therefore, we propose a simple procedure directly relying on the positions of the cell's trajectory and the covariance matrix of the positions. It is shown that the covariance is identical with the spatial aging correlation function for the supposed linear Gaussian models of Brownian motion with drift and fractional Brownian motion. The technique is applied and illustrated with simulated data showing a reliable parameter estimation from single cell paths.

Experimental Modal Analysis and Dynaic Strain Fiber Bragg Gratings for Structural Health Monitoring of Composite Aerospace Structures

NASA Astrophysics Data System (ADS)

Panopoulou, A.; Fransen, S.; Gomez Molinero, V.; Kostopoulos, V.

2012-07-01

The objective of this work is to develop a new structural health monitoring system for composite aerospace structures based on dynamic response strain measurements and experimental modal analysis techniques. Fibre Bragg Grating (FBG) optical sensors were used for monitoring the dynamic response of the composite structure. The structural dynamic behaviour has been numerically simulated and experimentally verified by means of vibration testing. The hypothesis of all vibration tests was that actual damage in composites reduces their stiffness and produces the same result as mass increase produces. Thus, damage was simulated by slightly varying locally the mass of the structure at different zones. Experimental modal analysis based on the strain responses was conducted and the extracted strain mode shapes were the input for the damage detection expert system. A feed-forward back propagation neural network was the core of the damage detection system. The features-input to the neural network consisted of the strain mode shapes, extracted from the experimental modal analysis. Dedicated training and validation activities were carried out based on the experimental results. The system showed high reliability, confirmed by the ability of the neural network to recognize the size and the position of damage on the structure. The experiments were performed on a real structure i.e. a lightweight antenna sub- reflector, manufactured and tested at EADS CASA ESPACIO. An integrated FBG sensor network, based on the advantage of multiplexing, was mounted on the structure with optimum topology. Numerical simulation of both structures was used as a support tool at all the steps of the work. Potential applications for the proposed system are during ground qualification extensive tests of space structures and during the mission as modal analysis tool on board, being able via the FBG responses to identify a potential failure.

Toward brain-computer interface based wheelchair control utilizing tactually-evoked event-related potentials

PubMed Central

2014-01-01

Background People with severe disabilities, e.g. due to neurodegenerative disease, depend on technology that allows for accurate wheelchair control. For those who cannot operate a wheelchair with a joystick, brain-computer interfaces (BCI) may offer a valuable option. Technology depending on visual or auditory input may not be feasible as these modalities are dedicated to processing of environmental stimuli (e.g. recognition of obstacles, ambient noise). Herein we thus validated the feasibility of a BCI based on tactually-evoked event-related potentials (ERP) for wheelchair control. Furthermore, we investigated use of a dynamic stopping method to improve speed of the tactile BCI system. Methods Positions of four tactile stimulators represented navigation directions (left thigh: move left; right thigh: move right; abdomen: move forward; lower neck: move backward) and N = 15 participants delivered navigation commands by focusing their attention on the desired tactile stimulus in an oddball-paradigm. Results Participants navigated a virtual wheelchair through a building and eleven participants successfully completed the task of reaching 4 checkpoints in the building. The virtual wheelchair was equipped with simulated shared-control sensors (collision avoidance), yet these sensors were rarely needed. Conclusion We conclude that most participants achieved tactile ERP-BCI control sufficient to reliably operate a wheelchair and dynamic stopping was of high value for tactile ERP classification. Finally, this paper discusses feasibility of tactile ERPs for BCI based wheelchair control. PMID:24428900

Time-lapse electrical impedance spectroscopy for monitoring the cell cycle of single immobilized S. pombe cells.

PubMed

Zhu, Zhen; Frey, Olivier; Haandbaek, Niels; Franke, Felix; Rudolf, Fabian; Hierlemann, Andreas

2015-11-26

As a complement and alternative to optical methods, wide-band electrical impedance spectroscopy (EIS) enables multi-parameter, label-free and real-time detection of cellular and subcellular features. We report on a microfluidics-based system designed to reliably capture single rod-shaped Schizosaccharomyces pombe cells by applying suction through orifices in a channel wall. The system enables subsequent culturing of immobilized cells in an upright position, while dynamic changes in cell-cycle state and morphology were continuously monitored through EIS over a broad frequency range. Besides measuring cell growth, clear impedance signals for nuclear division have been obtained. The EIS system has been characterized with respect to sensitivity and detection limits. The spatial resolution in measuring cell length was 0.25 μm, which corresponds to approximately a 5-min interval of cell growth under standard conditions. The comprehensive impedance data sets were also used to determine the occurrence of nuclear division and cytokinesis. The obtained results have been validated through concurrent confocal imaging and plausibilized through comparison with finite-element modeling data. The possibility to monitor cellular and intracellular features of single S. pombe cells during the cell cycle at high spatiotemporal resolution renders the presented microfluidics-based EIS system a suitable tool for dynamic single-cell investigations.

Dynamics of plasma proteome during leptin-replacement therapy in genetically based leptin deficiency.

PubMed

Andreev, V P; Dwivedi, R C; Paz-Filho, G; Krokhin, O V; Wong, M-L; Wilkins, J A; Licinio, J

2011-06-01

The effects of leptin-replacement therapy on the plasma proteome of three unique adults with genetically based leptin deficiency were studied longitudinally during the course of recombinant human leptin-replacement treatment. Quantitative proteomics analysis was performed in plasma samples collected during four stages: before leptin treatment was initiated, after 1.5 and 6 years of leptin-replacement treatment, and after 7 weeks of temporary interruption of leptin-replacement therapy. Of 500 proteins reliably identified and quantitated in those four stages, about 100 were differentially abundant twofold or more in one or more stages. Synchronous dynamics of abundances of about 90 proteins was observed reflecting both short- and long-term effects of leptin-replacement therapy. Pathways and processes enriched with overabundant synchronous proteins were cell adhesion, cytoskeleton remodeling, cell cycle, blood coagulation, glycolysis, and gluconeogenesis. Plausible common regulators of the above synchronous proteins were identified using transcription regulation network analysis. The generated network included two transcription factors (c-Myc and androgen receptor) that are known to activate each other through a double-positive feedback loop, which may represent a potential molecular mechanism for the long-term effects of leptin-replacement therapy. Our findings may help to elucidate the effects of leptin on insulin resistance.

Time-lapse electrical impedance spectroscopy for monitoring the cell cycle of single immobilized S. pombe cells

PubMed Central

Zhu, Zhen; Frey, Olivier; Haandbaek, Niels; Franke, Felix; Rudolf, Fabian; Hierlemann, Andreas

2015-01-01

As a complement and alternative to optical methods, wide-band electrical impedance spectroscopy (EIS) enables multi-parameter, label-free and real-time detection of cellular and subcellular features. We report on a microfluidics-based system designed to reliably capture single rod-shaped Schizosaccharomyces pombe cells by applying suction through orifices in a channel wall. The system enables subsequent culturing of immobilized cells in an upright position, while dynamic changes in cell-cycle state and morphology were continuously monitored through EIS over a broad frequency range. Besides measuring cell growth, clear impedance signals for nuclear division have been obtained. The EIS system has been characterized with respect to sensitivity and detection limits. The spatial resolution in measuring cell length was 0.25 μm, which corresponds to approximately a 5-min interval of cell growth under standard conditions. The comprehensive impedance data sets were also used to determine the occurrence of nuclear division and cytokinesis. The obtained results have been validated through concurrent confocal imaging and plausibilized through comparison with finite-element modeling data. The possibility to monitor cellular and intracellular features of single S. pombe cells during the cell cycle at high spatiotemporal resolution renders the presented microfluidics-based EIS system a suitable tool for dynamic single-cell investigations. PMID:26608589

A nonlinear heartbeat dynamics model approach for personalized emotion recognition.

PubMed

Valenza, Gaetano; Citi, Luca; Lanatà, Antonio; Scilingo, Enzo Pasquale; Barbieri, Riccardo

2013-01-01

Emotion recognition based on autonomic nervous system signs is one of the ambitious goals of affective computing. It is well-accepted that standard signal processing techniques require relative long-time series of multivariate records to ensure reliability and robustness of recognition and classification algorithms. In this work, we present a novel methodology able to assess cardiovascular dynamics during short-time (i.e. < 10 seconds) affective stimuli, thus overcoming some of the limitations of current emotion recognition approaches. We developed a personalized, fully parametric probabilistic framework based on point-process theory where heartbeat events are modelled using a 2(nd)-order nonlinear autoregressive integrative structure in order to achieve effective performances in short-time affective assessment. Experimental results show a comprehensive emotional characterization of 4 subjects undergoing a passive affective elicitation using a sequence of standardized images gathered from the international affective picture system. Each picture was identified by the IAPS arousal and valence scores as well as by a self-reported emotional label associating a subjective positive or negative emotion. Results show a clear classification of two defined levels of arousal, valence and self-emotional state using features coming from the instantaneous spectrum and bispectrum of the considered RR intervals, reaching up to 90% recognition accuracy.

Measurements and analyses of principal dynamic parameters of building structures as a function of type of vibration excitation

NASA Astrophysics Data System (ADS)

Bartmański, Cezary; Bochenek, Wojciech; Passia, Henryk; Szade, Adam

2006-06-01

The methods of direct measurement and analysis of the dynamic response of a building structure through real-time recording of the amplitude of low-frequency vibration (tilt) have been presented. Subject to analyses was the reaction induced either by kinematic excitation (road traffic and mining-induced vibration) or controlled action of solid-fuel rocket micro-engines installed on the building. The forces were analysed by means of a set of transducers installed both in the ground and on the structure. After the action of excitation forces has been stopped, the system (structure) makes damped vibration around the static equilibrium position. It has been shown that the type of excitation affects the accuracy of evaluation of principal dynamic parameters of the structure. In the authors opinion these are the decrement of damping and natural vibration frequency. Positive results of tests with the use of excitation by means of short-action (0.6 second) rocket micro-engines give a chance to develop a reliable method for periodical assessment of acceptable loss of usability characteristics of building structures heavily influenced by environmental effects.

Integration of Human Reliability Analysis Models into the Simulation-Based Framework for the Risk-Informed Safety Margin Characterization Toolkit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boring, Ronald; Mandelli, Diego; Rasmussen, Martin

2016-06-01

This report presents an application of a computation-based human reliability analysis (HRA) framework called the Human Unimodel for Nuclear Technology to Enhance Reliability (HUNTER). HUNTER has been developed not as a standalone HRA method but rather as framework that ties together different HRA methods to model dynamic risk of human activities as part of an overall probabilistic risk assessment (PRA). While we have adopted particular methods to build an initial model, the HUNTER framework is meant to be intrinsically flexible to new pieces that achieve particular modeling goals. In the present report, the HUNTER implementation has the following goals: •more » Integration with a high fidelity thermal-hydraulic model capable of modeling nuclear power plant behaviors and transients • Consideration of a PRA context • Incorporation of a solid psychological basis for operator performance • Demonstration of a functional dynamic model of a plant upset condition and appropriate operator response This report outlines these efforts and presents the case study of a station blackout scenario to demonstrate the various modules developed to date under the HUNTER research umbrella.« less

A Decentralized Compositional Framework for Dependable Decision Process in Self-Managed Cyber Physical Systems

PubMed Central

Hou, Kun-Mean; Zhang, Zhan

2017-01-01

Cyber Physical Systems (CPSs) need to interact with the changeable environment under various interferences. To provide continuous and high quality services, a self-managed CPS should automatically reconstruct itself to adapt to these changes and recover from failures. Such dynamic adaptation behavior introduces systemic challenges for CPS design, advice evaluation and decision process arrangement. In this paper, a formal compositional framework is proposed to systematically improve the dependability of the decision process. To guarantee the consistent observation of event orders for causal reasoning, this work first proposes a relative time-based method to improve the composability and compositionality of the timing property of events. Based on the relative time solution, a formal reference framework is introduced for self-managed CPSs, which includes a compositional FSM-based actor model (subsystems of CPS), actor-based advice and runtime decomposable decisions. To simplify self-management, a self-similar recursive actor interface is proposed for decision (actor) composition. We provide constraints and seven patterns for the composition of reliability and process time requirements. Further, two decentralized decision process strategies are proposed based on our framework, and we compare the reliability with the static strategy and the centralized processing strategy. The simulation results show that the one-order feedback strategy has high reliability, scalability and stability against the complexity of decision and random failure. This paper also shows a way to simplify the evaluation for dynamic system by improving the composability and compositionality of the subsystem. PMID:29120357

A Decentralized Compositional Framework for Dependable Decision Process in Self-Managed Cyber Physical Systems.

PubMed

Zhou, Peng; Zuo, Decheng; Hou, Kun-Mean; Zhang, Zhan

2017-11-09

Cyber Physical Systems (CPSs) need to interact with the changeable environment under various interferences. To provide continuous and high quality services, a self-managed CPS should automatically reconstruct itself to adapt to these changes and recover from failures. Such dynamic adaptation behavior introduces systemic challenges for CPS design, advice evaluation and decision process arrangement. In this paper, a formal compositional framework is proposed to systematically improve the dependability of the decision process. To guarantee the consistent observation of event orders for causal reasoning, this work first proposes a relative time-based method to improve the composability and compositionality of the timing property of events. Based on the relative time solution, a formal reference framework is introduced for self-managed CPSs, which includes a compositional FSM-based actor model (subsystems of CPS), actor-based advice and runtime decomposable decisions. To simplify self-management, a self-similar recursive actor interface is proposed for decision (actor) composition. We provide constraints and seven patterns for the composition of reliability and process time requirements. Further, two decentralized decision process strategies are proposed based on our framework, and we compare the reliability with the static strategy and the centralized processing strategy. The simulation results show that the one-order feedback strategy has high reliability, scalability and stability against the complexity of decision and random failure. This paper also shows a way to simplify the evaluation for dynamic system by improving the composability and compositionality of the subsystem.

A dynamic Thurstonian item response theory of motive expression in the picture story exercise: solving the internal consistency paradox of the PSE.

PubMed

Lang, Jonas W B

2014-07-01

The measurement of implicit or unconscious motives using the picture story exercise (PSE) has long been a target of debate in the psychological literature. Most debates have centered on the apparent paradox that PSE measures of implicit motives typically show low internal consistency reliability on common indices like Cronbach's alpha but nevertheless predict behavioral outcomes. I describe a dynamic Thurstonian item response theory (IRT) model that builds on dynamic system theories of motivation, theorizing on the PSE response process, and recent advancements in Thurstonian IRT modeling of choice data. To assess the models' capability to explain the internal consistency paradox, I first fitted the model to archival data (Gurin, Veroff, & Feld, 1957) and then simulated data based on bias-corrected model estimates from the real data. Simulation results revealed that the average squared correlation reliability for the motives in the Thurstonian IRT model was .74 and that Cronbach's alpha values were similar to the real data (<.35). These findings suggest that PSE motive measures have long been reliable and increase the scientific value of extant evidence from motivational research using PSE motive measures. (c) 2014 APA, all rights reserved.

Pre-shaping of the Fingertip of Robot Hand Covered with Net Structure Proximity Sensor

NASA Astrophysics Data System (ADS)

Suzuki, Kenji; Suzuki, Yosuke; Hasegawa, Hiroaki; Ming, Aiguo; Ishikawa, Masatoshi; Shimojo, Makoto

To achieve skillful tasks with multi-fingered robot hands, many researchers have been working on sensor-based control of them. Vision sensors and tactile sensors are indispensable for the tasks, however, the correctness of the information from the vision sensors decreases as a robot hand approaches to a grasping object because of occlusion. This research aims to achieve seamless detection for reliable grasp by use of proximity sensors: correcting the positional error of the hand in vision-based approach, and contacting the fingertip in the posture for effective tactile sensing. In this paper, we propose a method for adjusting the posture of the fingertip to the surface of the object. The method applies “Net-Structure Proximity Sensor” on the fingertip, which can detect the postural error in the roll and pitch axes between the fingertip and the object surface. The experimental result shows that the postural error is corrected in the both axes even if the object dynamically rotates.

Effect of forming gas annealing on the degradation properties of Ge-based MOS stacks

NASA Astrophysics Data System (ADS)

Aguirre, F.; Pazos, S.; Palumbo, F. R. M.; Fadida, S.; Winter, R.; Eizenberg, M.

2018-04-01

The influence of forming gas annealing on the degradation at a constant stress voltage of multi-layered germanium-based Metal-Oxide-Semiconductor capacitors (p-Ge/GeOx/Al2O3/High-K/Metal Gate) has been analyzed in terms of the C-V hysteresis and flat band voltage as a function of both negative and positive stress fields. Significant differences were found for the case of negative voltage stress between the annealed and non-annealed samples, independently of the stressing time. It was found that the hole trapping effect decreases in the case of the forming gas annealed samples, indicating strong passivation of defects with energies close to the valence band existing in the oxide-semiconductor interface during the forming gas annealing. Finally, a comparison between the degradation dynamics of Germanium and III-V (n-InGaAs) MOS stacks is presented to summarize the main challenges in the integration of reliable Ge-III-V hybrid devices.

Brief Communication: A low-cost Arduino®-based wire extensometer for earth flow monitoring

NASA Astrophysics Data System (ADS)

Guerriero, Luigi; Guerriero, Giovanni; Grelle, Gerardo; Guadagno, Francesco M.; Revellino, Paola

2017-06-01

Continuous monitoring of earth flow displacement is essential for the understanding of the dynamic of the process, its ongoing evolution and designing mitigation measures. Despite its importance, it is not always applied due to its expense and the need for integration with additional sensors to monitor factors controlling movement. To overcome these problems, we developed and tested a low-cost Arduino-based wire-rail extensometer integrating a data logger, a power system and multiple digital and analog inputs. The system is equipped with a high-precision position transducer that in the test configuration offers a measuring range of 1023 mm and an associated accuracy of ±1 mm, and integrates an operating temperature sensor that should allow potential thermal drift that typically affects this kind of systems to be identified and corrected. A field test, conducted at the Pietrafitta earth flow where additional monitoring systems had been installed, indicates a high reliability of the measurement and a high monitoring stability without visible thermal drift.

Mid-frequency Band Dynamics of Large Space Structures

NASA Technical Reports Server (NTRS)

Coppolino, Robert N.; Adams, Douglas S.

2004-01-01

High and low intensity dynamic environments experienced by a spacecraft during launch and on-orbit operations, respectively, induce structural loads and motions, which are difficult to reliably predict. Structural dynamics in low- and mid-frequency bands are sensitive to component interface uncertainty and non-linearity as evidenced in laboratory testing and flight operations. Analytical tools for prediction of linear system response are not necessarily adequate for reliable prediction of mid-frequency band dynamics and analysis of measured laboratory and flight data. A new MATLAB toolbox, designed to address the key challenges of mid-frequency band dynamics, is introduced in this paper. Finite-element models of major subassemblies are defined following rational frequency-wavelength guidelines. For computational efficiency, these subassemblies are described as linear, component mode models. The complete structural system model is composed of component mode subassemblies and linear or non-linear joint descriptions. Computation and display of structural dynamic responses are accomplished employing well-established, stable numerical methods, modern signal processing procedures and descriptive graphical tools. Parametric sensitivity and Monte-Carlo based system identification tools are used to reconcile models with experimental data and investigate the effects of uncertainties. Models and dynamic responses are exported for employment in applications, such as detailed structural integrity and mechanical-optical-control performance analyses.

Real-time identification of indoor pollutant source positions based on neural network locator of contaminant sources and optimized sensor networks.

PubMed

Vukovic, Vladimir; Tabares-Velasco, Paulo Cesar; Srebric, Jelena

2010-09-01

A growing interest in security and occupant exposure to contaminants revealed a need for fast and reliable identification of contaminant sources during incidental situations. To determine potential contaminant source positions in outdoor environments, current state-of-the-art modeling methods use computational fluid dynamic simulations on parallel processors. In indoor environments, current tools match accidental contaminant distributions with cases from precomputed databases of possible concentration distributions. These methods require intensive computations in pre- and postprocessing. On the other hand, neural networks emerged as a tool for rapid concentration forecasting of outdoor environmental contaminants such as nitrogen oxides or sulfur dioxide. All of these modeling methods depend on the type of sensors used for real-time measurements of contaminant concentrations. A review of the existing sensor technologies revealed that no perfect sensor exists, but intensity of work in this area provides promising results in the near future. The main goal of the presented research study was to extend neural network modeling from the outdoor to the indoor identification of source positions, making this technology applicable to building indoor environments. The developed neural network Locator of Contaminant Sources was also used to optimize number and allocation of contaminant concentration sensors for real-time prediction of indoor contaminant source positions. Such prediction should take place within seconds after receiving real-time contaminant concentration sensor data. For the purpose of neural network training, a multizone program provided distributions of contaminant concentrations for known source positions throughout a test building. Trained networks had an output indicating contaminant source positions based on measured concentrations in different building zones. A validation case based on a real building layout and experimental data demonstrated the ability of this method to identify contaminant source positions. Future research intentions are focused on integration with real sensor networks and model improvements for much more complicated contamination scenarios.

Comparison of Mechanical Axis and Dynamic Range Assessed with Weight Bearing Radiographs and Navigation System in Closed Wedge High Tibial Osteotomy

PubMed Central

Bae, Dae Kyung; Lee, Jong Whan; Cho, Seong Jin; Song, Sang Jun

2017-01-01

Purpose To compare navigation and weight bearing radiographic measurements of mechanical axis (MA) before and after closed wedge high tibial osteotomy (HTO) and to evaluate post-osteotomy changes in MA assessed during application of external varus or valgus force. Materials and Methods Data from 30 consecutive patients (30 knees) who underwent computer-assisted closed-wedge HTO were prospectively analyzed. Pre- and postoperative weight bearing radiographic evaluation of MA was performed. Under navigation guidance, pre- and post-osteotomy MA values were measured in an unloaded position. Any change in the post-osteotomy MA in response to external varus or valgus force, which was named as dynamic range, was evaluated with the navigation system. The navigation and weight bearing radiographic measurements were compared. Results Although there was a positive correlation between navigation and radiographic measurements, the reliability of navigation measurements of coronal alignment was reduced after osteotomy and wedge closing. The mean post-osteotomy MA value measured with the navigation was 3.5°±0.8° valgus in an unloaded position. It was 1.3°±0.8° valgus under varus force and 5.8°±1.1° valgus under valgus force. The average dynamic range was >±2°. Conclusions Potential differences between the postoperative MAs assessed by weight bearing radiographs and the navigation system in unloaded position should be considered during computer-assisted closed wedge HTO. Care should be taken to keep the dynamic range within the permissible range of alignment goal in HTO. PMID:28854769

Methods for Calculating Frequency of Maintenance of Complex Information Security System Based on Dynamics of Its Reliability

NASA Astrophysics Data System (ADS)

Varlataya, S. K.; Evdokimov, V. E.; Urzov, A. Y.

2017-11-01

This article describes a process of calculating a certain complex information security system (CISS) reliability using the example of the technospheric security management model as well as ability to determine the frequency of its maintenance using the system reliability parameter which allows one to assess man-made risks and to forecast natural and man-made emergencies. The relevance of this article is explained by the fact the CISS reliability is closely related to information security (IS) risks. Since reliability (or resiliency) is a probabilistic characteristic of the system showing the possibility of its failure (and as a consequence - threats to the protected information assets emergence), it is seen as a component of the overall IS risk in the system. As it is known, there is a certain acceptable level of IS risk assigned by experts for a particular information system; in case of reliability being a risk-forming factor maintaining an acceptable risk level should be carried out by the routine analysis of the condition of CISS and its elements and their timely service. The article presents a reliability parameter calculation for the CISS with a mixed type of element connection, a formula of the dynamics of such system reliability is written. The chart of CISS reliability change is a S-shaped curve which can be divided into 3 periods: almost invariable high level of reliability, uniform reliability reduction, almost invariable low level of reliability. Setting the minimum acceptable level of reliability, the graph (or formula) can be used to determine the period of time during which the system would meet requirements. Ideally, this period should not be longer than the first period of the graph. Thus, the proposed method of calculating the CISS maintenance frequency helps to solve a voluminous and critical task of the information assets risk management.

How we determined the most reliable solid medium for studying treatment of tuberculosis

PubMed Central

Heilig, Charles M.; Feng, Pei-Jean I.; Joloba, Moses L.; Johnson, John L.; Morgan, Karen; Gitta, Phineas; Boom, W. Henry; Mayanja-Kizza, Harriet; Eisenach, Kathleen D.; Bozeman, Lorna; Goldberg, Stefan V.

2014-01-01

Phase 2 clinical trials for tuberculosis (TB) treatment require reliable culture methods to determine presence or absence of Mycobacterium tuberculosis (Mtb) over the course of therapy, as these trials are based primarily on bacteriological endpoints. We evaluate which of 5 solid media is most reliable: Lowenstein-Jensen (LJ) egg-based medium and 4 Middlebrook agar media (nonselective 7H10 and 7H11 and selective 7H10 and 7H11). We analyze 393 specimens from 50 HIV-negative Ugandan adults with newly-diagnosed, pulmonary TB and high acid-fast bacillus smear grade. Specimens were collected every 2–4 weeks during the first 12 weeks of therapy. We compare the results for each culture to 2 composite reference standards—one that was deemed positive if any solid culture was positive for Mtb and another based on latent class analysis. Both reference standards established that the 2 selective Middlebrook media most reliably determine the presence or absence of Mtb (P<0.003), largely because of their lower contamination rates. We also showed that results on Middlebrook media were similar to each other, while LJ was most frequently discordant. Contaminated results appeared more likely to be truly negative than to harbor undetected Mtb. PMID:24661816

How we determined the most reliable solid medium for studying treatment of tuberculosis.

PubMed

Heilig, Charles M; Feng, Pei-Jean I; Joloba, Moses L; Johnson, John L; Morgan, Karen; Gitta, Phineas; Boom, W Henry; Mayanja-Kizza, Harriet; Eisenach, Kathleen D; Bozeman, Lorna; Goldberg, Stefan V

2014-05-01

Phase 2 clinical trials for tuberculosis (TB) treatment require reliable culture methods to determine presence or absence of Mycobacterium tuberculosis (Mtb) over the course of therapy, as these trials are based primarily on bacteriological endpoints. We evaluate which of 5 solid media is most reliable: Lowenstein-Jensen (LJ) egg-base medium and 4 Middlebrook agar media (nonselective 7H10 and 7H11 and selective 7H10 and 7H11). We analyze 393 specimens from 50 HIV-negative Ugandan adults with newly-diagnosed, pulmonary TB and high acid-fast bacillus smear grade. Specimens were collected every 2-4 weeks during the first 12 weeks of therapy. We compare the results for each culture to 2 composite reference standards--one that was deemed positive if any solid culture was positive for Mtb and another based on latent-class analysis. Both reference standards established that the 2 selective Middlebrook media most reliably determine the presence or absence of Mtb (P < 0.003), largely because of their lower contamination rates. We also showed that results on Middlebrook media were similar to each other, while LJ was most frequently discordant. Contaminated results appeared more likely to be truly negative than to harbor undetected Mtb. Published by Elsevier Ltd.

Realizing Crack Diagnosing and Self‐Healing by Electricity with a Dynamic Crosslinked Flexible Polyurethane Composite

PubMed Central

Pu, Wuli; Fu, Daihua; Wang, Zhanhua; Gan, Xinpeng; Lu, Xili; Yang, Li

2018-01-01

Abstract Combining self‐healing functions with damage diagnosing, which can achieve timely healing autonomously, is expected to improve the reliability and reduce life cycle cost of materials. Here, a flexible conductive composite composed of a dynamically crosslinked polyurethane bearing Diels–Alder bonds (PUDA) and carbon nanotubes (CNTs), which possess both crack diagnosing and self‐healing functions, is reported. The introduced dynamic Diels–Alder bonds endow the materials self‐healing function and the powder‐based preparation route based on the specially designed CNTs‐coated PUDA micropowders leads to the formation of segregated CNTs network, which makes the composite possess excellent mechanical properties and high conductivity. Because of the sufficient electrothermal and photothermal effect of CNTs, the composites can be healed rapidly and repeatedly by electricity or near‐infrared light based on the retro‐Diels–Alder reaction. An obvious color difference in the infrared thermograph resulting from the resistance difference between damaged and undamaged area can be observed when applying the voltage, which can be used for crack diagnosing. Using the same electrical circuit, the crack in the PUDA/CNTs composite can be noninvasively detected first and then be autonomously healed. The composites also exhibit a strain‐sensing function with good sensitivity and high reliability, thus will have potential applications in electronic strain sensors. PMID:29876226

Trajectory Specification for Terminal Air Traffic: Pairwise Conflict Detection and Resolution

NASA Technical Reports Server (NTRS)

Paielli, Russell A.; Erzberger, Heinz

2017-01-01

Trajectory Specification is the explicit bounding and control of aircraft trajectories such that the position at any point in time is constrained to a precisely defined volume of space. The bounding space is defined by cross-track, along-track, and vertical tolerances relative to a reference trajectory that specifies position as a function of time. The tolerances are dynamic and will be based on the aircraft navigation capabilities and the current traffic situation. Assuming conformance, Trajectory Specification can guarantee safe separation for an arbitrary period of time even in the event of an air traffic control (ATC) system or datalink failure; hence it can help to achieve the high level of safety and reliability needed for ATC automation. It can also reduce the reliance on tactical backup systems during normal operation. This paper applies it to the terminal area around a major airport and presents algorithms and software for detecting and resolving conflicts. A representative set of pairwise conflicts was generated, and a fast-time simulation was run on them. All conflicts were successfully resolved in real time, demonstrating the computational feasibility of the concept.

Reliability and validity of the Korean version of the community balance and mobility scale in patients with hemiplegia after stroke

PubMed Central

Lee, Kyoung-bo; Lee, Paul; Yoo, Sang-won; Kim, Young-dong

2016-01-01

[Purpose] The aim of this study was to translate and adapt the Community Balance and Mobility Scale (CB&M) into Korean (K-CB&M) and to verify the reliability and validity of scores obtained with Korean patients. [Subjects and Methods] A total of 16 subjects were recruited from St. Vincent’s Hospital in South Korea. At each testing session, subjects completed the K-CB&M, Berg balance scale (BBS), timed up and go test (TUG), and functional reaching test. All tests were administered by a physical therapist, and subjects completed the tests in an identical standardized order during all testing sessions. [Results] The inter- and intra-rater reliability coefficients were high for most subscores, while moderate inter-rater reliability was observed for the items “walking and looking” and “walk, look, and carry”, and moderate intra-rater reliability was observed for “forward to backward walking”. There was a positive correlation between the K-CB&M and BBS and a negative correlation between the K-CB&M and TUG in the convergent validity assessments. [Conclusion] The reliability and validity of the K-CB&M was high, suggesting that clinical practitioners treating Korean patients with hemiplegia can use this material for assessing static and dynamic balance. PMID:27630420

A common anchor facilitated GO-DNA nano-system for multiplex microRNA analysis in live cells.

PubMed

Yu, Jiantao; He, Sihui; Shao, Chen; Zhao, Haoran; Li, Jing; Tian, Leilei

2018-04-19

The design of a nano-system for the detection of intracellular microRNAs is challenging as it must fulfill complex requirements, i.e., it must have a high sensitivity to determine the dynamic expression level, a good reliability for multiplex and simultaneous detection, and a satisfactory biostability to work in biological environments. Instead of employing a commonly used physisorption or a full-conjugation strategy, here, a GO-DNA nano-system was developed under graft/base-pairing construction. The common anchor sequence was chemically grafted to GO to base-pair with various microRNA probes; and the hybridization with miRNAs drives the dyes on the probes to leave away from GO, resulting in "turned-on" fluorescence. This strategy not only simplifies the synthesis but also efficiently balances the loading yields of different probes. Moreover, the conjugation yield of GO with a base-paired hybrid has been improved by more than two-fold compared to that of the conjugation with a single strand. We demonstrated that base-paired DNA probes could be efficiently delivered into cells along with GO and are properly stabilized by the conjugated anchor sequence. The resultant GO-DNA nano-system exhibited high stability in a complex biological environment and good resistance to nucleases, and was able to accurately discriminate various miRNAs without cross-reaction. With all of these positive features, the GO-DNA nano-system can simultaneously detect three miRNAs and monitor their dynamic expression levels.

Multi-Unmanned Aerial Vehicle (UAV) Cooperative Fault Detection Employing Differential Global Positioning (DGPS), Inertial and Vision Sensors.

PubMed

Heredia, Guillermo; Caballero, Fernando; Maza, Iván; Merino, Luis; Viguria, Antidio; Ollero, Aníbal

2009-01-01

This paper presents a method to increase the reliability of Unmanned Aerial Vehicle (UAV) sensor Fault Detection and Identification (FDI) in a multi-UAV context. Differential Global Positioning System (DGPS) and inertial sensors are used for sensor FDI in each UAV. The method uses additional position estimations that augment individual UAV FDI system. These additional estimations are obtained using images from the same planar scene taken from two different UAVs. Since accuracy and noise level of the estimation depends on several factors, dynamic replanning of the multi-UAV team can be used to obtain a better estimation in case of faults caused by slow growing errors of absolute position estimation that cannot be detected by using local FDI in the UAVs. Experimental results with data from two real UAVs are also presented.

BDS/GPS Dual Systems Positioning Based on the Modified SR-UKF Algorithm

PubMed Central

Kong, JaeHyok; Mao, Xuchu; Li, Shaoyuan

2016-01-01

The Global Navigation Satellite System can provide all-day three-dimensional position and speed information. Currently, only using the single navigation system cannot satisfy the requirements of the system’s reliability and integrity. In order to improve the reliability and stability of the satellite navigation system, the positioning method by BDS and GPS navigation system is presented, the measurement model and the state model are described. Furthermore, the modified square-root Unscented Kalman Filter (SR-UKF) algorithm is employed in BDS and GPS conditions, and analysis of single system/multi-system positioning has been carried out, respectively. The experimental results are compared with the traditional estimation results, which show that the proposed method can perform highly-precise positioning. Especially when the number of satellites is not adequate enough, the proposed method combine BDS and GPS systems to achieve a higher positioning precision. PMID:27153068

Facial expression movement enhances the measurement of temporal dynamics of attentional bias in the dot-probe task.

PubMed

Caudek, Corrado; Ceccarini, Francesco; Sica, Claudio

2017-08-01

The facial dot-probe task is one of the most common experimental paradigms used to assess attentional bias toward emotional information. In recent years, however, the psychometric properties of this paradigm have been questioned. In the present study, attentional bias to emotional face stimuli was measured with dynamic and static images of realistic human faces in 97 college students (63 women) who underwent either a positive or a negative mood-induction prior to the experiment. We controlled the bottom-up salience of the stimuli in order to dissociate the top-down orienting of attention from the effects of the bottom-up physical properties of the stimuli. A Bayesian analysis of our results indicates that 1) the traditional global attentional bias index shows a low reliability, 2) reliability increases dramatically when biased attention is analyzed by extracting a series of bias estimations from trial-to-trial (Zvielli, Bernstein, & Koster, 2015), 3) dynamic expression of emotions strengthens biased attention to emotional information, and 4) mood-congruency facilitates the measurement of biased attention to emotional stimuli. These results highlight the importance of using ecologically valid stimuli in attentional bias research, together with the importance of estimating biased attention at the trial level. Copyright © 2017 Elsevier Ltd. All rights reserved.

Study on the influence of stochastic properties of correction terms on the reliability of instantaneous network RTK

NASA Astrophysics Data System (ADS)

Próchniewicz, Dominik

2014-03-01

The reliability of precision GNSS positioning primarily depends on correct carrier-phase ambiguity resolution. An optimal estimation and correct validation of ambiguities necessitates a proper definition of mathematical positioning model. Of particular importance in the model definition is the taking into account of the atmospheric errors (ionospheric and tropospheric refraction) as well as orbital errors. The use of the network of reference stations in kinematic positioning, known as Network-based Real-Time Kinematic (Network RTK) solution, facilitates the modeling of such errors and their incorporation, in the form of correction terms, into the functional description of positioning model. Lowered accuracy of corrections, especially during atmospheric disturbances, results in the occurrence of unaccounted biases, the so-called residual errors. The taking into account of such errors in Network RTK positioning model is possible by incorporating the accuracy characteristics of the correction terms into the stochastic model of observations. In this paper we investigate the impact of the expansion of the stochastic model to include correction term variances on the reliability of the model solution. In particular the results of instantaneous solution that only utilizes a single epoch of GPS observations, is analyzed. Such a solution mode due to the low number of degrees of freedom is very sensitive to an inappropriate mathematical model definition. Thus the high level of the solution reliability is very difficult to achieve. Numerical tests performed for a test network located in mountain area during ionospheric disturbances allows to verify the described method for the poor measurement conditions. The results of the ambiguity resolution as well as the rover positioning accuracy shows that the proposed method of stochastic modeling can increase the reliability of instantaneous Network RTK performance.

A distributed scheme to manage the dynamic coexistence of IEEE 802.15.4-based health-monitoring WBANs.

PubMed

Deylami, Mohammad N; Jovanov, Emil

2014-01-01

The overlap of transmission ranges between wireless networks as a result of mobility is referred to as dynamic coexistence. The interference caused by coexistence may significantly affect the performance of wireless body area networks (WBANs) where reliability is particularly critical for health monitoring applications. In this paper, we analytically study the effects of dynamic coexistence on the operation of IEEE 802.15.4-based health monitoring WBANs. The current IEEE 802.15.4 standard lacks mechanisms for effectively managing the coexistence of mobile WBANs. Considering the specific characteristics and requirements of health monitoring WBANs, we propose the dynamic coexistence management (DCM) mechanism to make IEEE 802.15.4-based WBANs able to detect and mitigate the harmful effects of coexistence. We assess the effectiveness of this scheme using extensive OPNET simulations. Our results indicate that DCM improves the successful transmission rates of dynamically coexisting WBANs by 20%-25% for typical medical monitoring applications.

Reliability of Soft Tissue Model Based Implant Surgical Guides; A Methodological Mistake.

PubMed

Sabour, Siamak; Dastjerdi, Elahe Vahid

2012-08-20

Abstract We were interested to read the paper by Maney P and colleagues published in the July 2012 issue of J Oral Implantol. The authors aimed to assess the reliability of soft tissue model based implant surgical guides reported that the accuracy was evaluated using software. 1 I found the manuscript title of Maney P, et al. incorrect and misleading. Moreover, they reported twenty-two sites (46.81%) were considered accurate (13 of 24 maxillary and 9 of 23 mandibular sites). As the authors point out in their conclusion, Soft tissue models do not always provide sufficient accuracy for implant surgical guide fabrication.Reliability (precision) and validity (accuracy) are two different methodological issues in researches. Sensitivity, specificity, PPV, NPV, likelihood ratio positive (true positive/false negative) and likelihood ratio negative (false positive/ true negative) as well as odds ratio (true results\\false results - preferably more than 50) are among the tests to evaluate the validity (accuracy) of a single test compared to a gold standard.2-4 It is not clear that the reported twenty-two sites (46.81%) which were considered accurate related to which of the above mentioned estimates for validity analysis. Reliability (repeatability or reproducibility) is being assessed by different statistical tests such as Pearson r, least square and paired t.test which all of them are among common mistakes in reliability analysis 5. Briefly, for quantitative variable Intra Class Correlation Coefficient (ICC) and for qualitative variables weighted kappa should be used with caution because kappa has its own limitation too. Regarding reliability or agreement, it is good to know that for computing kappa value, just concordant cells are being considered, whereas discordant cells should also be taking into account in order to reach a correct estimation of agreement (Weighted kappa).2-4 As a take home message, for reliability and validity analysis, appropriate tests should be applied.

A Squeezed Artificial Neural Network for the Symbolic Network Reliability Functions of Binary-State Networks.

PubMed

Yeh, Wei-Chang

Network reliability is an important index to the provision of useful information for decision support in the modern world. There is always a need to calculate symbolic network reliability functions (SNRFs) due to dynamic and rapid changes in network parameters. In this brief, the proposed squeezed artificial neural network (SqANN) approach uses the Monte Carlo simulation to estimate the corresponding reliability of a given designed matrix from the Box-Behnken design, and then the Taguchi method is implemented to find the appropriate number of neurons and activation functions of the hidden layer and the output layer in ANN to evaluate SNRFs. According to the experimental results of the benchmark networks, the comparison appears to support the superiority of the proposed SqANN method over the traditional ANN-based approach with at least 16.6% improvement in the median absolute deviation in the cost of extra 2 s on average for all experiments.Network reliability is an important index to the provision of useful information for decision support in the modern world. There is always a need to calculate symbolic network reliability functions (SNRFs) due to dynamic and rapid changes in network parameters. In this brief, the proposed squeezed artificial neural network (SqANN) approach uses the Monte Carlo simulation to estimate the corresponding reliability of a given designed matrix from the Box-Behnken design, and then the Taguchi method is implemented to find the appropriate number of neurons and activation functions of the hidden layer and the output layer in ANN to evaluate SNRFs. According to the experimental results of the benchmark networks, the comparison appears to support the superiority of the proposed SqANN method over the traditional ANN-based approach with at least 16.6% improvement in the median absolute deviation in the cost of extra 2 s on average for all experiments.

Real-time positioning technology in horizontal directional drilling based on magnetic gradient tensor measurement

NASA Astrophysics Data System (ADS)

Deng, Guoqing; Yao, Aiguo

2017-04-01

Horizontal directional drilling (HDD) technology has been widely used in Civil Engineering. The dynamic position of the drill bit during construction is one of significant facts determining the accuracy of the trajectory of HDD. A new method now has been proposed to detecting the position of drill bit by measuring the magnetic gradient tensor of the ground solenoid magnetic beacon. Compared with traditional HDD positioning technologies, this new model is much easier to apply with lower request for construction sites and higher positioning efficiency. A direct current (DC) solenoid as a magnetic dipole is placed on ground near the drill bit, and related sensors array which contains four Micro-electromechanical Systems (MEMS ) tri-axial magnetometers, one MEMS tri-axial accelerometer and one MEMS tri-axial gyroscope is set up for measuring the magnetic gradient tensor of the magnetic dipole. The related HDD positioning model has been established and simulation experiments have been carried out to verify the feasibility and reliability of the proposed method. The experiments show that this method has good positioning accuracy in horizontal and vertical direction, and totally avoid the impact of the environmental magnetic field. It can be found that the posture of the magnetic beacon will impact the remote positioning precision within valid positioning range, and the positioning accuracy is higher with longer baseline for limited space in drilling tools. The results prove that the relative error can be limited in 2% by adjusting position of the magnetic beacon, the layers of the enameled coil, the sensitive of magnetometers and the baseline distance. Conclusion can be made that this new method can be applied in HDD positioning with better effect and wider application range than traditional method.

Inter-operator Reliability of Magnetic Resonance Image-Based Computational Fluid Dynamics Prediction of Cerebrospinal Fluid Motion in the Cervical Spine.

PubMed

Martin, Bryn A; Yiallourou, Theresia I; Pahlavian, Soroush Heidari; Thyagaraj, Suraj; Bunck, Alexander C; Loth, Francis; Sheffer, Daniel B; Kröger, Jan Robert; Stergiopulos, Nikolaos

2016-05-01

For the first time, inter-operator dependence of MRI based computational fluid dynamics (CFD) modeling of cerebrospinal fluid (CSF) in the cervical spinal subarachnoid space (SSS) is evaluated. In vivo MRI flow measurements and anatomy MRI images were obtained at the cervico-medullary junction of a healthy subject and a Chiari I malformation patient. 3D anatomies of the SSS were reconstructed by manual segmentation by four independent operators for both cases. CFD results were compared at nine axial locations along the SSS in terms of hydrodynamic and geometric parameters. Intraclass correlation (ICC) assessed the inter-operator agreement for each parameter over the axial locations and coefficient of variance (CV) compared the percentage of variance for each parameter between the operators. Greater operator dependence was found for the patient (0.19 < ICC < 0.99) near the craniovertebral junction compared to the healthy subject (ICC > 0.78). For the healthy subject, hydraulic diameter and Womersley number had the least variance (CV = ~2%). For the patient, peak diastolic velocity and Reynolds number had the smallest variance (CV = ~3%). These results show a high degree of inter-operator reliability for MRI-based CFD simulations of CSF flow in the cervical spine for healthy subjects and a lower degree of reliability for patients with Type I Chiari malformation.

On the use and the performance of software reliability growth models

NASA Technical Reports Server (NTRS)

Keiller, Peter A.; Miller, Douglas R.

1991-01-01

We address the problem of predicting future failures for a piece of software. The number of failures occurring during a finite future time interval is predicted from the number failures observed during an initial period of usage by using software reliability growth models. Two different methods for using the models are considered: straightforward use of individual models, and dynamic selection among models based on goodness-of-fit and quality-of-prediction criteria. Performance is judged by the relative error of the predicted number of failures over future finite time intervals relative to the number of failures eventually observed during the intervals. Six of the former models and eight of the latter are evaluated, based on their performance on twenty data sets. Many open questions remain regarding the use and the performance of software reliability growth models.

Reliability Evaluation and Improvement Approach of Chemical Production Man - Machine - Environment System

NASA Astrophysics Data System (ADS)

Miao, Yongchun; Kang, Rongxue; Chen, Xuefeng

2017-12-01

In recent years, with the gradual extension of reliability research, the study of production system reliability has become the hot topic in various industries. Man-machine-environment system is a complex system composed of human factors, machinery equipment and environment. The reliability of individual factor must be analyzed in order to gradually transit to the research of three-factor reliability. Meanwhile, the dynamic relationship among man-machine-environment should be considered to establish an effective blurry evaluation mechanism to truly and effectively analyze the reliability of such systems. In this paper, based on the system engineering, fuzzy theory, reliability theory, human error, environmental impact and machinery equipment failure theory, the reliabilities of human factor, machinery equipment and environment of some chemical production system were studied by the method of fuzzy evaluation. At last, the reliability of man-machine-environment system was calculated to obtain the weighted result, which indicated that the reliability value of this chemical production system was 86.29. Through the given evaluation domain it can be seen that the reliability of man-machine-environment integrated system is in a good status, and the effective measures for further improvement were proposed according to the fuzzy calculation results.

Optimal blood glucose level control using dynamic programming based on minimal Bergman model

NASA Astrophysics Data System (ADS)

Rettian Anggita Sari, Maria; Hartono

2018-03-01

The purpose of this article is to simulate the glucose dynamic and the insulin kinetic of diabetic patient. The model used in this research is a non-linear Minimal Bergman model. Optimal control theory is then applied to formulate the problem in order to determine the optimal dose of insulin in the treatment of diabetes mellitus such that the glucose level is in the normal range for some specific time range. The optimization problem is solved using dynamic programming. The result shows that dynamic programming is quite reliable to represent the interaction between glucose and insulin levels in diabetes mellitus patient.

Evaluating reliability of WSN with sleep/wake-up interfering nodes

NASA Astrophysics Data System (ADS)

Distefano, Salvatore

2013-10-01

A wireless sensor network (WSN) (singular and plural of acronyms are spelled the same) is a distributed system composed of autonomous sensor nodes wireless connected and randomly scattered into a geographical area to cooperatively monitor physical or environmental conditions. Adequate techniques and strategies are required to manage a WSN so that it works properly, observing specific quantities and metrics to evaluate the WSN operational conditions. Among them, one of the most important is the reliability. Considering a WSN as a system composed of sensor nodes the system reliability approach can be applied, thus expressing the WSN reliability in terms of its nodes' reliability. More specifically, since often standby power management policies are applied at node level and interferences among nodes may arise, a WSN can be considered as a dynamic system. In this article we therefore consider the WSN reliability evaluation problem from the dynamic system reliability perspective. Static-structural interactions are specified by the WSN topology. Sleep/wake-up standby policies and interferences due to wireless communications can be instead considered as dynamic aspects. Thus, in order to represent and to evaluate the WSN reliability, we use dynamic reliability block diagrams and Petri nets. The proposed technique allows to overcome the limits of Markov models when considering non-linear discharge processes, since they cannot adequately represent the aging processes. In order to demonstrate the effectiveness of the technique, we investigate some specific WSN network topologies, providing guidelines for their representation and evaluation.

Predictive Coding of Dynamical Variables in Balanced Spiking Networks

PubMed Central

Boerlin, Martin; Machens, Christian K.; Denève, Sophie

2013-01-01

Two observations about the cortex have puzzled neuroscientists for a long time. First, neural responses are highly variable. Second, the level of excitation and inhibition received by each neuron is tightly balanced at all times. Here, we demonstrate that both properties are necessary consequences of neural networks that represent information efficiently in their spikes. We illustrate this insight with spiking networks that represent dynamical variables. Our approach is based on two assumptions: We assume that information about dynamical variables can be read out linearly from neural spike trains, and we assume that neurons only fire a spike if that improves the representation of the dynamical variables. Based on these assumptions, we derive a network of leaky integrate-and-fire neurons that is able to implement arbitrary linear dynamical systems. We show that the membrane voltage of the neurons is equivalent to a prediction error about a common population-level signal. Among other things, our approach allows us to construct an integrator network of spiking neurons that is robust against many perturbations. Most importantly, neural variability in our networks cannot be equated to noise. Despite exhibiting the same single unit properties as widely used population code models (e.g. tuning curves, Poisson distributed spike trains), balanced networks are orders of magnitudes more reliable. Our approach suggests that spikes do matter when considering how the brain computes, and that the reliability of cortical representations could have been strongly underestimated. PMID:24244113

Automatic identification of solid-phase medication intake using wireless wearable accelerometers.

PubMed

Rui Wang; Sitova, Zdenka; Xiaoqing Jia; Xiang He; Abramson, Tobi; Gasti, Paolo; Balagani, Kiran S; Farajidavar, Aydin

2014-01-01

We have proposed a novel solution to a fundamental problem encountered in implementing non-ingestion based medical adherence monitoring systems, namely, how to reliably identify pill medication intake. We show how wireless wearable devices with tri-axial accelerometer can be used to detect and classify hand gestures of users during solid-phase medication intake. Two devices were worn on the wrists of each user. Users were asked to perform two activities in the way that is natural and most comfortable to them: (1) taking empty gelatin capsules with water, and (2) drinking water and wiping mouth. 25 users participated in this study. The signals obtained from the devices were filtered and the patterns were identified using dynamic time warping algorithm. Using hand gesture signals, we achieved 84.17 percent true positive rate and 13.33 percent false alarm rate, thus demonstrating that the hand gestures could be used to effectively identify pill taking activity.

The Occurrence Rate of Hot Jupiters

NASA Astrophysics Data System (ADS)

Rampalli, Rayna; Catanzarite, Joseph; Batalha, Natalie M.

2017-01-01

As the first kind of exoplanet to be discovered, hot Jupiters have always been objects of interest. Despite being prevalent in radial velocity and ground-based surveys, they were found to be much rarer based on Kepler observations. These data show a pile-up at radii of 9-22 Rearth and orbital periods of 1-10 days. Computing accurate occurrence rates can lend insight into planet-formation and migration-theories. To get a more accurate look, the idea of reliability was introduced. Each hot Jupiter candidate was assigned a reliability based on its location in the galactic plane and likelihood of being a false positive. Numbers were updated if ground-based follow-up indicated a candidate was indeed a false positive. These reliabilities were introduced into an occurrence rate calculation and yielded about a 12% decrease in occurrence rate for each period bin examined and a 25% decrease across all the bins. To get a better idea of the cause behind the pileup, occurrence rates based on parent stellar metallicity were calculated. As expected from previous work, higher metallicity stars yield higher occurrence rates. Future work includes examining period distributions in both the high metallicity and low metallicity sample for a better understanding and confirmation of the pile-up effect.

Reliability of Measurement of Glenohumeral Internal Rotation, External Rotation, and Total Arc of Motion in 3 Test Positions

PubMed Central

Kevern, Mark A.; Beecher, Michael; Rao, Smita

2014-01-01

Context: Athletes who participate in throwing and racket sports consistently demonstrate adaptive changes in glenohumeral-joint internal and external rotation in the dominant arm. Measurements of these motions have demonstrated excellent intrarater and poor interrater reliability. Objective: To determine intrarater reliability, interrater reliability, and standard error of measurement for shoulder internal rotation, external rotation, and total arc of motion using an inclinometer in 3 testing procedures in National Collegiate Athletic Association Division I baseball and softball athletes. Design: Cross-sectional study. Setting: Athletic department. Patients or Other Participants Thirty-eight players participated in the study. Shoulder internal rotation, external rotation, and total arc of motion were measured by 2 investigators in 3 test positions. The standard supine position was compared with a side-lying test position, as well as a supine test position without examiner overpressure. Results: Excellent intrarater reliability was noted for all 3 test positions and ranges of motion, with intraclass correlation coefficient values ranging from 0.93 to 0.99. Results for interrater reliability were less favorable. Reliability for internal rotation was highest in the side-lying position (0.68) and reliability for external rotation and total arc was highest in the supine-without-overpressure position (0.774 and 0.713, respectively). The supine-with-overpressure position yielded the lowest interrater reliability results in all positions. The side-lying position had the most consistent results, with very little variation among intraclass correlation coefficient values for the various test positions. Conclusions: The results of our study clearly indicate that the side-lying test procedure is of equal or greater value than the traditional supine-with-overpressure method. PMID:25188316

Understanding the effect of an excessive cold tongue bias on projecting the tropical Pacific SST warming pattern in CMIP5 models

NASA Astrophysics Data System (ADS)

Ying, Jun; Huang, Ping; Lian, Tao; Tan, Hongjian

2018-05-01

An excessive cold tongue is a common bias among current climate models, and considered an important source of bias in projections of tropical Pacific climate change under global warming. Specifically, the excessive cold tongue bias is closely related to the tropical Pacific SST warming (TPSW) pattern. In this study, we reveal that two processes are the critical mechanisms by which the excessive cold tongue bias influences the projection of the TPSW pattern, based on 32 models from phase 5 of Coupled Model Intercomparison Projection (CMIP5). On the one hand, by assuming that the shortwave (SW) radiation to SST feedback is linearly correlated to the cold tongue SST, the excessive cold tongue bias can induce an overly weak negative SW-SST feedback in the central Pacific, which can lead to a positive SST warming bias in the central to western Pacific (around 150°E-140°W). Moreover, the overly weak local atmospheric dynamics response to SST is a key process of the overly weak SW-SST feedback, compared with the cloud response to atmospheric dynamics and the SW radiation response to cloud. On the other hand, the overly strong ocean zonal overturning circulation associated with the excessive cold tongue bias results in an overestimation of the ocean dynamical thermostat effect, with enhanced ocean stratification under global warming, leading to a negative SST warming bias in the central and eastern Pacific (around 170°W-120°W). These two processes jointly form a positive SST warming bias in the western Pacific, contributing to a La Niña-like warming bias. Therefore, we suggest a more realistic climatological cold tongue SST is needed for a more reliable projection of the TPSW pattern.

A double candidate survivable routing protocol for HAP network

NASA Astrophysics Data System (ADS)

He, Panfeng; Li, Chunyue; Ni, Shuyan

2016-11-01

To improve HAP network invulnerability, and at the same time considering the quasi-dynamic topology in HAP network, a simple and reliable routing protocol is proposed in the paper. The protocol firstly uses a double-candidate strategy for the next-node select to provide better robustness. Then during the maintenance stage, short hello packets instead of long routing packets are used only to check link connectivity in the quasi-dynamic HAP network. The route maintenance scheme based on short hello packets can greatly reduce link spending. Simulation results based on OPNET demonstrate the effectiveness of the proposed routing protocol.

A Novel Bit-level Image Encryption Method Based on Chaotic Map and Dynamic Grouping

NASA Astrophysics Data System (ADS)

Zhang, Guo-Ji; Shen, Yan

2012-10-01

In this paper, a novel bit-level image encryption method based on dynamic grouping is proposed. In the proposed method, the plain-image is divided into several groups randomly, then permutation-diffusion process on bit level is carried out. The keystream generated by logistic map is related to the plain-image, which confuses the relationship between the plain-image and the cipher-image. The computer simulation results of statistical analysis, information entropy analysis and sensitivity analysis show that the proposed encryption method is secure and reliable enough to be used for communication application.

Future climate change enhances rainfall seasonality in a regional model of western Maritime Continent

NASA Astrophysics Data System (ADS)

Kang, Suchul; Im, Eun-Soon; Eltahir, Elfatih A. B.

2018-03-01

In this study, future changes in rainfall due to global climate change are investigated over the western Maritime Continent based on dynamically downscaled climate projections using the MIT Regional Climate Model (MRCM) with 12 km horizontal resolution. A total of nine 30-year regional climate projections driven by multi-GCMs projections (CCSM4, MPI-ESM-MR and ACCESS1.0) under multi-scenarios of greenhouse gases emissions (Historical: 1976-2005, RCP4.5 and RCP8.5: 2071-2100) from phase 5 of the Coupled Model Inter-comparison Project (CMIP5) are analyzed. Focusing on dynamically downscaled rainfall fields, the associated systematic biases originating from GCM and MRCM are removed based on observations using Parametric Quantile Mapping method in order to enhance the reliability of future projections. The MRCM simulations with bias correction capture the spatial patterns of seasonal rainfall as well as the frequency distribution of daily rainfall. Based on projected rainfall changes under both RCP4.5 and RCP8.5 scenarios, the ensemble of MRCM simulations project a significant decrease in rainfall over the western Maritime Continent during the inter-monsoon periods while the change in rainfall is not relevant during wet season. The main mechanism behind the simulated decrease in rainfall is rooted in asymmetries of the projected changes in seasonal dynamics of the meridional circulation along different latitudes. The sinking motion, which is marginally positioned in the reference simulation, is enhanced and expanded under global climate change, particularly in RCP8.5 scenario during boreal fall season. The projected enhancement of rainfall seasonality over the western Maritime Continent suggests increased risk of water stress for natural ecosystems as well as man-made water resources reservoirs.

Dynamic Infrared Thermography Study of Blood Flow Relative to Lower Limp Position

NASA Astrophysics Data System (ADS)

Stathopoulos, I.; Skouroliakou, K.; Michail, C.; Valais, I.

2015-09-01

Thermography is an established method for studying skin temperature distribution. Temperature distribution on body surface is influenced by a variety of physiological mechanisms and has been proven a reliable indicator of various physiological disorders. Blood flow is an important factor that influences body heat diffusion and skin temperature. In an attempt to validate and further elucidate thermal models characterizing the human skin, dynamic thermography of the lower limp in horizontal and vertical position was performed, using a FLIR T460 thermographic camera. Temporal variation of temperature was recorded on five distinct points of the limp. Specific points were initially cooled by the means of an ice cube and measurements of the skin temperature were obtained every 30 seconds as the skin temperature was locally reduced and afterwards restored at its initial value. The return to thermal balance followed roughly the same pattern for all points of measurement, although the heating rate was faster when the foot was in horizontal position. Thermal balance was achieved faster at the spots that were positioned on a vein passage. Our results confirm the influence of blood flow on the thermal regulation of the skin. Spots located over veins exhibit different thermal behaviour due to thermal convection through blood flow. Changing the position of the foot from vertical to horizontal, effectively affects blood perfusion as in the vertical position blood circulation is opposed by gravity.

A Study of Vicon System Positioning Performance.

PubMed

Merriaux, Pierre; Dupuis, Yohan; Boutteau, Rémi; Vasseur, Pascal; Savatier, Xavier

2017-07-07

Motion capture setups are used in numerous fields. Studies based on motion capture data can be found in biomechanical, sport or animal science. Clinical science studies include gait analysis as well as balance, posture and motor control. Robotic applications encompass object tracking. Today's life applications includes entertainment or augmented reality. Still, few studies investigate the positioning performance of motion capture setups. In this paper, we study the positioning performance of one player in the optoelectronic motion capture based on markers: Vicon system. Our protocol includes evaluations of static and dynamic performances. Mean error as well as positioning variabilities are studied with calibrated ground truth setups that are not based on other motion capture modalities. We introduce a new setup that enables directly estimating the absolute positioning accuracy for dynamic experiments contrary to state-of-the art works that rely on inter-marker distances. The system performs well on static experiments with a mean absolute error of 0.15 mm and a variability lower than 0.025 mm. Our dynamic experiments were carried out at speeds found in real applications. Our work suggests that the system error is less than 2 mm. We also found that marker size and Vicon sampling rate must be carefully chosen with respect to the speed encountered in the application in order to reach optimal positioning performance that can go to 0.3 mm for our dynamic study.

Determination of Quantum Chemistry Based Force Fields for Molecular Dynamics Simulations of Aromatic Polymers

NASA Technical Reports Server (NTRS)

Jaffe, Richard; Langhoff, Stephen R. (Technical Monitor)

1995-01-01

Ab initio quantum chemistry calculations for model molecules can be used to parameterize force fields for molecular dynamics simulations of polymers. Emphasis in our research group is on using quantum chemistry-based force fields for molecular dynamics simulations of organic polymers in the melt and glassy states, but the methodology is applicable to simulations of small molecules, multicomponent systems and solutions. Special attention is paid to deriving reliable descriptions of the non-bonded and electrostatic interactions. Several procedures have been developed for deriving and calibrating these parameters. Our force fields for aromatic polyimide simulations will be described. In this application, the intermolecular interactions are the critical factor in determining many properties of the polymer (including its color).

Image contrast mechanisms in dynamic friction force microscopy: Antimony particles on graphite

NASA Astrophysics Data System (ADS)

Mertens, Felix; Göddenhenrich, Thomas; Dietzel, Dirk; Schirmeisen, Andre

2017-01-01

Dynamic Friction Force Microscopy (DFFM) is a technique based on Atomic Force Microscopy (AFM) where resonance oscillations of the cantilever are excited by lateral actuation of the sample. During this process, the AFM tip in contact with the sample undergoes a complex movement which consists of alternating periods of sticking and sliding. Therefore, DFFM can give access to dynamic transition effects in friction that are not accessible by alternative techniques. Using antimony nanoparticles on graphite as a model system, we analyzed how combined influences of friction and topography can effect different experimental configurations of DFFM. Based on the experimental results, for example, contrast inversion between fractional resonance and band excitation imaging strategies to extract reliable tribological information from DFFM images are devised.

Relaxation estimation of RMSD in molecular dynamics immunosimulations.

PubMed

Schreiner, Wolfgang; Karch, Rudolf; Knapp, Bernhard; Ilieva, Nevena

2012-01-01

Molecular dynamics simulations have to be sufficiently long to draw reliable conclusions. However, no method exists to prove that a simulation has converged. We suggest the method of "lagged RMSD-analysis" as a tool to judge if an MD simulation has not yet run long enough. The analysis is based on RMSD values between pairs of configurations separated by variable time intervals Δt. Unless RMSD(Δt) has reached a stationary shape, the simulation has not yet converged.

Rapid diagnosis of tuberculosis in dromedary camel (Camelus dromedarius) using lateral flow assay-based kit.

PubMed

Ranjan, Rakesh; Narnaware, Shirish D; Nath, Kashi; Sawal, R K; Patil, N V

2018-04-01

Accurate early antemortem diagnosis of tuberculosis in dromedary camels is difficult due to the lack of reliable diagnostic test. The present study aimed to evaluate a lateral flow assay-based kit (rapid assay kit) in tuberculosis diagnosis that employs immuno-chromatographic detection of antibodies in serum, plasma, or whole blood. In a dromedary camel herd comprising 337 animals located at Bikaner, Rajasthan, India, 50 adult weak camels (11 males and 39 females) were tested by applying a single intradermal tuberculin test (SIDT) and rapid assay kit. A total of 14 animals (2 males, 12 females) were found positive in rapid assay. In SIDT, four animals revealed a positive reaction in the neck region and seven animals in the tail base. Another male animal was found SIDT positive but negative in rapid assay; it died after 12 months. Nine rapid assay positive animals died asymptomatically in 1- to 11-month period revealing postmortem tuberculosis lesions that were confirmed by Ziehl-Neelsen staining and histopathology. No tuberculous lesion was evident in the animal found positive in SIDT alone. Results of the present study indicated that serological tests like rapid assay kit can serve as a reliable test for antemortem diagnosis of tuberculosis in dromedary camel.

Distributed cooperative control of AC microgrids

NASA Astrophysics Data System (ADS)

Bidram, Ali

In this dissertation, the comprehensive secondary control of electric power microgrids is of concern. Microgrid technical challenges are mainly realized through the hierarchical control structure, including primary, secondary, and tertiary control levels. Primary control level is locally implemented at each distributed generator (DG), while the secondary and tertiary control levels are conventionally implemented through a centralized control structure. The centralized structure requires a central controller which increases the reliability concerns by posing the single point of failure. In this dissertation, the distributed control structure using the distributed cooperative control of multi-agent systems is exploited to increase the secondary control reliability. The secondary control objectives are microgrid voltage and frequency, and distributed generators (DGs) active and reactive powers. Fully distributed control protocols are implemented through distributed communication networks. In the distributed control structure, each DG only requires its own information and the information of its neighbors on the communication network. The distributed structure obviates the requirements for a central controller and complex communication network which, in turn, improves the system reliability. Since the DG dynamics are nonlinear and non-identical, input-output feedback linearization is used to transform the nonlinear dynamics of DGs to linear dynamics. Proposed control frameworks cover the control of microgrids containing inverter-based DGs. Typical microgrid test systems are used to verify the effectiveness of the proposed control protocols.

Towards Smart Grid Dynamic Ratings

NASA Astrophysics Data System (ADS)

Cheema, Jamal; Clark, Adrian; Kilimnik, Justin; Pavlovski, Chris; Redman, David; Vu, Maria

2011-08-01

The energy distribution industry is giving greater attention to smart grid solutions as a means for increasing the capabilities, efficiency and reliability of the electrical power network. The smart grid makes use of intelligent monitoring and control devices throughout the distribution network to report on electrical properties such as voltage, current and power, as well as raising network alarms and events. A further aspect of the smart grid embodies the dynamic rating of electrical assets of the network. This fundamentally involves a rating of the load current capacity of electrical assets including feeders, transformers and switches. The mainstream approach to rate assets is to apply the vendor plate rating, which often under utilizes assets, or in some cases over utilizes when environmental conditions reduce the effective rated capacity, potentially reducing lifetime. Using active intelligence we have developed a rating system that rates assets in real time based upon several events. This allows for a far more efficient and reliable electrical grid that is able to extend further the life and reliability of the electrical network. In this paper we describe our architecture, the observations made during development and live deployment of the solution into operation. We also illustrate how this solution blends with the smart grid by proposing a dynamic rating system for the smart grid.

Accuracy Enhancement of Inertial Sensors Utilizing High Resolution Spectral Analysis

PubMed Central

Noureldin, Aboelmagd; Armstrong, Justin; El-Shafie, Ahmed; Karamat, Tashfeen; McGaughey, Don; Korenberg, Michael; Hussain, Aini

2012-01-01

In both military and civilian applications, the inertial navigation system (INS) and the global positioning system (GPS) are two complementary technologies that can be integrated to provide reliable positioning and navigation information for land vehicles. The accuracy enhancement of INS sensors and the integration of INS with GPS are the subjects of widespread research. Wavelet de-noising of INS sensors has had limited success in removing the long-term (low-frequency) inertial sensor errors. The primary objective of this research is to develop a novel inertial sensor accuracy enhancement technique that can remove both short-term and long-term error components from inertial sensor measurements prior to INS mechanization and INS/GPS integration. A high resolution spectral analysis technique called the fast orthogonal search (FOS) algorithm is used to accurately model the low frequency range of the spectrum, which includes the vehicle motion dynamics and inertial sensor errors. FOS models the spectral components with the most energy first and uses an adaptive threshold to stop adding frequency terms when fitting a term does not reduce the mean squared error more than fitting white noise. The proposed method was developed, tested and validated through road test experiments involving both low-end tactical grade and low cost MEMS-based inertial systems. The results demonstrate that in most cases the position accuracy during GPS outages using FOS de-noised data is superior to the position accuracy using wavelet de-noising.

Twist Model Development and Results from the Active Aeroelastic Wing F/A-18 Aircraft

NASA Technical Reports Server (NTRS)

Lizotte, Andrew M.; Allen, Michael J.

2007-01-01

Understanding the wing twist of the active aeroelastic wing (AAW) F/A-18 aircraft is a fundamental research objective for the program and offers numerous benefits. In order to clearly understand the wing flexibility characteristics, a model was created to predict real-time wing twist. A reliable twist model allows the prediction of twist for flight simulation, provides insight into aircraft performance uncertainties, and assists with computational fluid dynamic and aeroelastic issues. The left wing of the aircraft was heavily instrumented during the first phase of the active aeroelastic wing program allowing deflection data collection. Traditional data processing steps were taken to reduce flight data, and twist predictions were made using linear regression techniques. The model predictions determined a consistent linear relationship between the measured twist and aircraft parameters, such as surface positions and aircraft state variables. Error in the original model was reduced in some cases by using a dynamic pressure-based assumption. This technique produced excellent predictions for flight between the standard test points and accounted for nonlinearities in the data. This report discusses data processing techniques and twist prediction validation, and provides illustrative and quantitative results.

On continuous user authentication via typing behavior.

PubMed

Roth, Joseph; Liu, Xiaoming; Metaxas, Dimitris

2014-10-01

We hypothesize that an individual computer user has a unique and consistent habitual pattern of hand movements, independent of the text, while typing on a keyboard. As a result, this paper proposes a novel biometric modality named typing behavior (TB) for continuous user authentication. Given a webcam pointing toward a keyboard, we develop real-time computer vision algorithms to automatically extract hand movement patterns from the video stream. Unlike the typical continuous biometrics, such as keystroke dynamics (KD), TB provides a reliable authentication with a short delay, while avoiding explicit key-logging. We collect a video database where 63 unique subjects type static text and free text for multiple sessions. For one typing video, the hands are segmented in each frame and a unique descriptor is extracted based on the shape and position of hands, as well as their temporal dynamics in the video sequence. We propose a novel approach, named bag of multi-dimensional phrases, to match the cross-feature and cross-temporal pattern between a gallery sequence and probe sequence. The experimental results demonstrate a superior performance of TB when compared with KD, which, together with our ultrareal-time demo system, warrant further investigation of this novel vision application and biometric modality.

Design and Optimization Method of a Two-Disk Rotor System

NASA Astrophysics Data System (ADS)

Huang, Jingjing; Zheng, Longxi; Mei, Qing

2016-04-01

An integrated analytical method based on multidisciplinary optimization software Isight and general finite element software ANSYS was proposed in this paper. Firstly, a two-disk rotor system was established and the mode, humorous response and transient response at acceleration condition were analyzed with ANSYS. The dynamic characteristics of the two-disk rotor system were achieved. On this basis, the two-disk rotor model was integrated to the multidisciplinary design optimization software Isight. According to the design of experiment (DOE) and the dynamic characteristics, the optimization variables, optimization objectives and constraints were confirmed. After that, the multi-objective design optimization of the transient process was carried out with three different global optimization algorithms including Evolutionary Optimization Algorithm, Multi-Island Genetic Algorithm and Pointer Automatic Optimizer. The optimum position of the two-disk rotor system was obtained at the specified constraints. Meanwhile, the accuracy and calculation numbers of different optimization algorithms were compared. The optimization results indicated that the rotor vibration reached the minimum value and the design efficiency and quality were improved by the multidisciplinary design optimization in the case of meeting the design requirements, which provided the reference to improve the design efficiency and reliability of the aero-engine rotor.

Twist Model Development and Results From the Active Aeroelastic Wing F/A-18 Aircraft

NASA Technical Reports Server (NTRS)

Lizotte, Andrew; Allen, Michael J.

2005-01-01

Understanding the wing twist of the active aeroelastic wing F/A-18 aircraft is a fundamental research objective for the program and offers numerous benefits. In order to clearly understand the wing flexibility characteristics, a model was created to predict real-time wing twist. A reliable twist model allows the prediction of twist for flight simulation, provides insight into aircraft performance uncertainties, and assists with computational fluid dynamic and aeroelastic issues. The left wing of the aircraft was heavily instrumented during the first phase of the active aeroelastic wing program allowing deflection data collection. Traditional data processing steps were taken to reduce flight data, and twist predictions were made using linear regression techniques. The model predictions determined a consistent linear relationship between the measured twist and aircraft parameters, such as surface positions and aircraft state variables. Error in the original model was reduced in some cases by using a dynamic pressure-based assumption and by using neural networks. These techniques produced excellent predictions for flight between the standard test points and accounted for nonlinearities in the data. This report discusses data processing techniques and twist prediction validation, and provides illustrative and quantitative results.

Survey on Ranging Sensors and Cooperative Techniques for Relative Positioning of Vehicles

PubMed Central

de Ponte Müller, Fabian

2017-01-01

Future driver assistance systems will rely on accurate, reliable and continuous knowledge on the position of other road participants, including pedestrians, bicycles and other vehicles. The usual approach to tackle this requirement is to use on-board ranging sensors inside the vehicle. Radar, laser scanners or vision-based systems are able to detect objects in their line-of-sight. In contrast to these non-cooperative ranging sensors, cooperative approaches follow a strategy in which other road participants actively support the estimation of the relative position. The limitations of on-board ranging sensors regarding their detection range and angle of view and the facility of blockage can be approached by using a cooperative approach based on vehicle-to-vehicle communication. The fusion of both, cooperative and non-cooperative strategies, seems to offer the largest benefits regarding accuracy, availability and robustness. This survey offers the reader a comprehensive review on different techniques for vehicle relative positioning. The reader will learn the important performance indicators when it comes to relative positioning of vehicles, the different technologies that are both commercially available and currently under research, their expected performance and their intrinsic limitations. Moreover, the latest research in the area of vision-based systems for vehicle detection, as well as the latest work on GNSS-based vehicle localization and vehicular communication for relative positioning of vehicles, are reviewed. The survey also includes the research work on the fusion of cooperative and non-cooperative approaches to increase the reliability and the availability. PMID:28146129

An Autonomous Distributed Fault-Tolerant Local Positioning System

NASA Technical Reports Server (NTRS)

Malekpour, Mahyar R.

2017-01-01

We describe a fault-tolerant, GPS-independent (Global Positioning System) distributed autonomous positioning system for static/mobile objects and present solutions for providing highly-accurate geo-location data for the static/mobile objects in dynamic environments. The reliability and accuracy of a positioning system fundamentally depends on two factors; its timeliness in broadcasting signals and the knowledge of its geometry, i.e., locations and distances of the beacons. Existing distributed positioning systems either synchronize to a common external source like GPS or establish their own time synchrony using a scheme similar to a master-slave by designating a particular beacon as the master and other beacons synchronize to it, resulting in a single point of failure. Another drawback of existing positioning systems is their lack of addressing various fault manifestations, in particular, communication link failures, which, as in wireless networks, are increasingly dominating the process failures and are typically transient and mobile, in the sense that they typically affect different messages to/from different processes over time.

IMU-Based Online Kinematic Calibration of Robot Manipulator

PubMed Central

2013-01-01

Robot calibration is a useful diagnostic method for improving the positioning accuracy in robot production and maintenance. An online robot self-calibration method based on inertial measurement unit (IMU) is presented in this paper. The method requires that the IMU is rigidly attached to the robot manipulator, which makes it possible to obtain the orientation of the manipulator with the orientation of the IMU in real time. This paper proposed an efficient approach which incorporates Factored Quaternion Algorithm (FQA) and Kalman Filter (KF) to estimate the orientation of the IMU. Then, an Extended Kalman Filter (EKF) is used to estimate kinematic parameter errors. Using this proposed orientation estimation method will result in improved reliability and accuracy in determining the orientation of the manipulator. Compared with the existing vision-based self-calibration methods, the great advantage of this method is that it does not need the complex steps, such as camera calibration, images capture, and corner detection, which make the robot calibration procedure more autonomous in a dynamic manufacturing environment. Experimental studies on a GOOGOL GRB3016 robot show that this method has better accuracy, convenience, and effectiveness than vision-based methods. PMID:24302854

Reliability and validity of the Outcome Expectations for Exercise Scale-2.

PubMed

Resnick, Barbara

2005-10-01

Development of a reliable and valid measure of outcome expectations for exercise for older adults will help establish the relationship between outcome expectations and exercise and facilitate the development of interventions to increase physical activity in older adults. The purpose of this study was to test the reliability and validity of the Outcome Expectations for Exercise-2 Scale (OEE-2), a 13-item measure with two subscales: positive OEE (POEE) and negative OEE (NOEE). The OEE-2 scale was given to 161 residents in a continuing-care retirement community. There was some evidence of validity based on confirmatory factor analysis, Rasch-analysis INFIT and OUTFIT statistics, and convergent validity and test criterion relationships. There was some evidence for reliability of the OEE-2 based on alpha coefficients, person- and item-separation reliability indexes, and R(2)values. Based on analyses, suggested revisions are provided for future use of the OEE-2. Although ongoing reliability and validity testing are needed, the OEE-2 scale can be used to identify older adults with low outcome expectations for exercise, and interventions can then be implemented to strengthen these expectations and improve exercise behavior.

Kepler Planet Reliability Metrics: Astrophysical Positional Probabilities for Data Release 25

NASA Technical Reports Server (NTRS)

Bryson, Stephen T.; Morton, Timothy D.

2017-01-01

This document is very similar to KSCI-19092-003, Planet Reliability Metrics: Astrophysical Positional Probabilities, which describes the previous release of the astrophysical positional probabilities for Data Release 24. The important changes for Data Release 25 are:1. The computation of the astrophysical positional probabilities uses the Data Release 25 processed pixel data for all Kepler Objects of Interest.2. Computed probabilities now have associated uncertainties, whose computation is described in x4.1.3.3. The scene modeling described in x4.1.2 uses background stars detected via ground-based high-resolution imaging, described in x5.1, that are not in the Kepler Input Catalog or UKIRT catalog. These newly detected stars are presented in Appendix B. Otherwise the text describing the algorithms and examples is largely unchanged from KSCI-19092-003.

Patient-reported outcome instruments that evaluate adherence behaviours in adults with asthma: A systematic review of measurement properties.

PubMed

Gagné, Myriam; Boulet, Louis-Philippe; Pérez, Norma; Moisan, Jocelyne

2018-04-30

To systematically identify the measurement properties of patient-reported outcome instruments (PROs) that evaluate adherence to inhaled maintenance medication in adults with asthma. We conducted a systematic review of six databases. Two reviewers independently included studies on the measurement properties of PROs that evaluated adherence in asthmatic participants aged ≥18 years. Based on the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN), the reviewers (1) extracted data on internal consistency, reliability, measurement error, content validity, structural validity, hypotheses testing, cross-cultural validity, criterion validity, and responsiveness; (2) assessed the methodological quality of the included studies; (3) assessed the quality of the measurement properties (positive or negative); and (4) summarised the level of evidence (limited, moderate, or strong). We screened 6,068 records and included 15 studies (14 PROs). No studies evaluated measurement error or responsiveness. Based on methodological and measurement property quality assessments, we found limited positive evidence of: (a) internal consistency of the Adherence Questionnaire, Refined Medication Adherence Reason Scale (MAR-Scale), Medication Adherence Report Scale for Asthma (MARS-A), and Test of the Adherence to Inhalers (TAI); (b) reliability of the TAI; and (c) structural validity of the Adherence Questionnaire, MAR-Scale, MARS-A, and TAI. We also found limited negative evidence of: (d) hypotheses testing of Adherence Questionnaire; (e) reliability of the MARS-A; and (f) criterion validity of the MARS-A and TAI. Our results highlighted the need to conduct further high-quality studies that will positively evaluate the reliability, validity, and responsiveness of the available PROs. This article is protected by copyright. All rights reserved.

Reliable detection of fluence anomalies in EPID-based IMRT pretreatment quality assurance using pixel intensity deviations

PubMed Central

Gordon, J. J.; Gardner, J. K.; Wang, S.; Siebers, J. V.

2012-01-01

Purpose: This work uses repeat images of intensity modulated radiation therapy (IMRT) fields to quantify fluence anomalies (i.e., delivery errors) that can be reliably detected in electronic portal images used for IMRT pretreatment quality assurance. Methods: Repeat images of 11 clinical IMRT fields are acquired on a Varian Trilogy linear accelerator at energies of 6 MV and 18 MV. Acquired images are corrected for output variations and registered to minimize the impact of linear accelerator and electronic portal imaging device (EPID) positioning deviations. Detection studies are performed in which rectangular anomalies of various sizes are inserted into the images. The performance of detection strategies based on pixel intensity deviations (PIDs) and gamma indices is evaluated using receiver operating characteristic analysis. Results: Residual differences between registered images are due to interfraction positional deviations of jaws and multileaf collimator leaves, plus imager noise. Positional deviations produce large intensity differences that degrade anomaly detection. Gradient effects are suppressed in PIDs using gradient scaling. Background noise is suppressed using median filtering. In the majority of images, PID-based detection strategies can reliably detect fluence anomalies of ≥5% in ∼1 mm2 areas and ≥2% in ∼20 mm2 areas. Conclusions: The ability to detect small dose differences (≤2%) depends strongly on the level of background noise. This in turn depends on the accuracy of image registration, the quality of the reference image, and field properties. The longer term aim of this work is to develop accurate and reliable methods of detecting IMRT delivery errors and variations. The ability to resolve small anomalies will allow the accuracy of advanced treatment techniques, such as image guided, adaptive, and arc therapies, to be quantified. PMID:22894421

Engineering evaluation of SSME dynamic data from engine tests and SSV flights

NASA Technical Reports Server (NTRS)

1986-01-01

An engineering evaluation of dynamic data from SSME hot firing tests and SSV flights is summarized. The basic objective of the study is to provide analyses of vibration, strain and dynamic pressure measurements in support of MSFC performance and reliability improvement programs. A brief description of the SSME test program is given and a typical test evaluation cycle reviewed. Data banks generated to characterize SSME component dynamic characteristics are described and statistical analyses performed on these data base measurements are discussed. Analytical models applied to define the dynamic behavior of SSME components (such as turbopump bearing elements and the flight accelerometer safety cut-off system) are also summarized. Appendices are included to illustrate some typical tasks performed under this study.

Efficient reliability analysis of structures with the rotational quasi-symmetric point- and the maximum entropy methods

NASA Astrophysics Data System (ADS)

Xu, Jun; Dang, Chao; Kong, Fan

2017-10-01

This paper presents a new method for efficient structural reliability analysis. In this method, a rotational quasi-symmetric point method (RQ-SPM) is proposed for evaluating the fractional moments of the performance function. Then, the derivation of the performance function's probability density function (PDF) is carried out based on the maximum entropy method in which constraints are specified in terms of fractional moments. In this regard, the probability of failure can be obtained by a simple integral over the performance function's PDF. Six examples, including a finite element-based reliability analysis and a dynamic system with strong nonlinearity, are used to illustrate the efficacy of the proposed method. All the computed results are compared with those by Monte Carlo simulation (MCS). It is found that the proposed method can provide very accurate results with low computational effort.

Applications of computerized adaptive testing (CAT) to the assessment of headache impact.

PubMed

Ware, John E; Kosinski, Mark; Bjorner, Jakob B; Bayliss, Martha S; Batenhorst, Alice; Dahlöf, Carl G H; Tepper, Stewart; Dowson, Andrew

2003-12-01

To evaluate the feasibility of computerized adaptive testing (CAT) and the reliability and validity of CAT-based estimates of headache impact scores in comparison with 'static' surveys. Responses to the 54-item Headache Impact Test (HIT) were re-analyzed for recent headache sufferers (n = 1016) who completed telephone interviews during the National Survey of Headache Impact (NSHI). Item response theory (IRT) calibrations and the computerized dynamic health assessment (DYNHA) software were used to simulate CAT assessments by selecting the most informative items for each person and estimating impact scores according to pre-set precision standards (CAT-HIT). Results were compared with IRT estimates based on all items (total-HIT), computerized 6-item dynamic estimates (CAT-HIT-6), and a developmental version of a 'static' 6-item form (HIT-6-D). Analyses focused on: respondent burden (survey length and administration time), score distributions ('ceiling' and 'floor' effects), reliability and standard errors, and clinical validity (diagnosis, level of severity). A random sample (n = 245) was re-assessed to test responsiveness. A second study (n = 1103) compared actual CAT surveys and an improved 'static' HIT-6 among current headache sufferers sampled on the Internet. Respondents completed measures from the first study and the generic SF-8 Health Survey; some (n = 540) were re-tested on the Internet after 2 weeks. In the first study, simulated CAT-HIT and total-HIT scores were highly correlated (r = 0.92) without 'ceiling' or 'floor' effects and with a substantial reduction (90.8%) in respondent burden. Six of the 54 items accounted for the great majority of item administrations (3603/5028, 77.6%). CAT-HIT reliability estimates were very high (0.975-0.992) in the range where 95% of respondents scored, and relative validity (RV) coefficients were high for diagnosis (RV = 0.87) and severity (RV = 0.89); patient-level classifications were accurate 91.3% for a diagnosis of migraine. For all three criteria of change, CAT-HIT scores were more responsive than all other measures. In the second study, estimates of respondent burden, item usage, reliability and clinical validity were replicated. The test-retest reliability of CAT-HIT was 0.79 and alternate forms coefficients ranged from 0.85 to 0.91. All correlations with the generic SF-8 were negative. CAT-based administrations of headache impact items achieved very large reductions in respondent burden without compromising validity for purposes of patient screening or monitoring changes in headache impact over time. IRT models and CAT-based dynamic health assessments warrant testing among patients with other conditions.

AUV Positioning Method Based on Tightly Coupled SINS/LBL for Underwater Acoustic Multipath Propagation.

PubMed

Zhang, Tao; Shi, Hongfei; Chen, Liping; Li, Yao; Tong, Jinwu

2016-03-11

This paper researches an AUV (Autonomous Underwater Vehicle) positioning method based on SINS (Strapdown Inertial Navigation System)/LBL (Long Base Line) tightly coupled algorithm. This algorithm mainly includes SINS-assisted searching method of optimum slant-range of underwater acoustic propagation multipath, SINS/LBL tightly coupled model and multi-sensor information fusion algorithm. Fuzzy correlation peak problem of underwater LBL acoustic propagation multipath could be solved based on SINS positional information, thus improving LBL positional accuracy. Moreover, introduction of SINS-centered LBL locating information could compensate accumulative AUV position error effectively and regularly. Compared to loosely coupled algorithm, this tightly coupled algorithm can still provide accurate location information when there are fewer than four available hydrophones (or within the signal receiving range). Therefore, effective positional calibration area of tightly coupled system based on LBL array is wider and has higher reliability and fault tolerance than loosely coupled. It is more applicable to AUV positioning based on SINS/LBL.

AUV Positioning Method Based on Tightly Coupled SINS/LBL for Underwater Acoustic Multipath Propagation

PubMed Central

Zhang, Tao; Shi, Hongfei; Chen, Liping; Li, Yao; Tong, Jinwu

2016-01-01

This paper researches an AUV (Autonomous Underwater Vehicle) positioning method based on SINS (Strapdown Inertial Navigation System)/LBL (Long Base Line) tightly coupled algorithm. This algorithm mainly includes SINS-assisted searching method of optimum slant-range of underwater acoustic propagation multipath, SINS/LBL tightly coupled model and multi-sensor information fusion algorithm. Fuzzy correlation peak problem of underwater LBL acoustic propagation multipath could be solved based on SINS positional information, thus improving LBL positional accuracy. Moreover, introduction of SINS-centered LBL locating information could compensate accumulative AUV position error effectively and regularly. Compared to loosely coupled algorithm, this tightly coupled algorithm can still provide accurate location information when there are fewer than four available hydrophones (or within the signal receiving range). Therefore, effective positional calibration area of tightly coupled system based on LBL array is wider and has higher reliability and fault tolerance than loosely coupled. It is more applicable to AUV positioning based on SINS/LBL. PMID:26978361

The Cause of Category-Based Distortions in Spatial Memory: A Distribution Analysis

ERIC Educational Resources Information Center

Sampaio, Cristina; Wang, Ranxiao Frances

2017-01-01

Recall of remembered locations reliably reflects a compromise between a target's true position and its region's prototypical position. The effect is quite robust, and a standard interpretation for these data is that the metric and categorical codings blend in a Bayesian combinatory fashion. However, there has been no direct experimental evidence…

Comparison of ensemble post-processing approaches, based on empirical and dynamical error modelisation of rainfall-runoff model forecasts

NASA Astrophysics Data System (ADS)

Chardon, J.; Mathevet, T.; Le Lay, M.; Gailhard, J.

2012-04-01

In the context of a national energy company (EDF : Electricité de France), hydro-meteorological forecasts are necessary to ensure safety and security of installations, meet environmental standards and improve water ressources management and decision making. Hydrological ensemble forecasts allow a better representation of meteorological and hydrological forecasts uncertainties and improve human expertise of hydrological forecasts, which is essential to synthesize available informations, coming from different meteorological and hydrological models and human experience. An operational hydrological ensemble forecasting chain has been developed at EDF since 2008 and is being used since 2010 on more than 30 watersheds in France. This ensemble forecasting chain is characterized ensemble pre-processing (rainfall and temperature) and post-processing (streamflow), where a large human expertise is solicited. The aim of this paper is to compare 2 hydrological ensemble post-processing methods developed at EDF in order improve ensemble forecasts reliability (similar to Monatanari &Brath, 2004; Schaefli et al., 2007). The aim of the post-processing methods is to dress hydrological ensemble forecasts with hydrological model uncertainties, based on perfect forecasts. The first method (called empirical approach) is based on a statistical modelisation of empirical error of perfect forecasts, by streamflow sub-samples of quantile class and lead-time. The second method (called dynamical approach) is based on streamflow sub-samples of quantile class and streamflow variation, and lead-time. On a set of 20 watersheds used for operational forecasts, results show that both approaches are necessary to ensure a good post-processing of hydrological ensemble, allowing a good improvement of reliability, skill and sharpness of ensemble forecasts. The comparison of the empirical and dynamical approaches shows the limits of the empirical approach which is not able to take into account hydrological dynamic and processes, i. e. sample heterogeneity. For a same streamflow range corresponds different processes such as rising limbs or recession, where uncertainties are different. The dynamical approach improves reliability, skills and sharpness of forecasts and globally reduces confidence intervals width. When compared in details, the dynamical approach allows a noticeable reduction of confidence intervals during recessions where uncertainty is relatively lower and a slight increase of confidence intervals during rising limbs or snowmelt where uncertainty is greater. The dynamic approach, validated by forecaster's experience that considered the empirical approach not discriminative enough, improved forecaster's confidence and communication of uncertainties. Montanari, A. and Brath, A., (2004). A stochastic approach for assessing the uncertainty of rainfall-runoff simulations. Water Resources Research, 40, W01106, doi:10.1029/2003WR002540. Schaefli, B., Balin Talamba, D. and Musy, A., (2007). Quantifying hydrological modeling errors through a mixture of normal distributions. Journal of Hydrology, 332, 303-315.

Local-feature analysis for automated coarse-graining of bulk-polymer molecular dynamics simulations.

PubMed

Xue, Y; Ludovice, P J; Grover, M A

2012-12-01

A method for automated coarse-graining of bulk polymers is presented, using the data-mining tool of local feature analysis. Most existing methods for polymer coarse-graining define superatoms based on their covalent bonding topology along the polymer backbone, but here superatoms are defined based only on their correlated motions, as observed in molecular dynamics simulations. Correlated atomic motions are identified in the simulation data using local feature analysis, between atoms in the same or in different polymer chains. Groups of highly correlated atoms constitute the superatoms in the coarse-graining scheme, and the positions of their seed coordinates are then projected forward in time. Based on only the seed positions, local feature analysis enables the full reconstruction of all atomic positions. This reconstruction suggests an iterative scheme to reduce the computation of the simulations to initialize another short molecular dynamic simulation, identify new superatoms, and again project forward in time.

ADEPT, a dynamic next generation sequencing data error-detection program with trimming

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Shihai; Lo, Chien-Chi; Li, Po-E

Illumina is the most widely used next generation sequencing technology and produces millions of short reads that contain errors. These sequencing errors constitute a major problem in applications such as de novo genome assembly, metagenomics analysis and single nucleotide polymorphism discovery. In this study, we present ADEPT, a dynamic error detection method, based on the quality scores of each nucleotide and its neighboring nucleotides, together with their positions within the read and compares this to the position-specific quality score distribution of all bases within the sequencing run. This method greatly improves upon other available methods in terms of the truemore » positive rate of error discovery without affecting the false positive rate, particularly within the middle of reads. We conclude that ADEPT is the only tool to date that dynamically assesses errors within reads by comparing position-specific and neighboring base quality scores with the distribution of quality scores for the dataset being analyzed. The result is a method that is less prone to position-dependent under-prediction, which is one of the most prominent issues in error prediction. The outcome is that ADEPT improves upon prior efforts in identifying true errors, primarily within the middle of reads, while reducing the false positive rate.« less

ADEPT, a dynamic next generation sequencing data error-detection program with trimming

DOE PAGES

Feng, Shihai; Lo, Chien-Chi; Li, Po-E; ...

2016-02-29

Illumina is the most widely used next generation sequencing technology and produces millions of short reads that contain errors. These sequencing errors constitute a major problem in applications such as de novo genome assembly, metagenomics analysis and single nucleotide polymorphism discovery. In this study, we present ADEPT, a dynamic error detection method, based on the quality scores of each nucleotide and its neighboring nucleotides, together with their positions within the read and compares this to the position-specific quality score distribution of all bases within the sequencing run. This method greatly improves upon other available methods in terms of the truemore » positive rate of error discovery without affecting the false positive rate, particularly within the middle of reads. We conclude that ADEPT is the only tool to date that dynamically assesses errors within reads by comparing position-specific and neighboring base quality scores with the distribution of quality scores for the dataset being analyzed. The result is a method that is less prone to position-dependent under-prediction, which is one of the most prominent issues in error prediction. The outcome is that ADEPT improves upon prior efforts in identifying true errors, primarily within the middle of reads, while reducing the false positive rate.« less

Relaxation Estimation of RMSD in Molecular Dynamics Immunosimulations

PubMed Central

Schreiner, Wolfgang; Karch, Rudolf; Knapp, Bernhard; Ilieva, Nevena

2012-01-01

Molecular dynamics simulations have to be sufficiently long to draw reliable conclusions. However, no method exists to prove that a simulation has converged. We suggest the method of “lagged RMSD-analysis” as a tool to judge if an MD simulation has not yet run long enough. The analysis is based on RMSD values between pairs of configurations separated by variable time intervals Δt. Unless RMSD(Δt) has reached a stationary shape, the simulation has not yet converged. PMID:23019425

Reliability Issues and Solutions in Flexible Electronics Under Mechanical Fatigue

NASA Astrophysics Data System (ADS)

Yi, Seol-Min; Choi, In-Suk; Kim, Byoung-Joon; Joo, Young-Chang

2018-07-01

Flexible devices are of significant interest due to their potential expansion of the application of smart devices into various fields, such as energy harvesting, biological applications and consumer electronics. Due to the mechanically dynamic operations of flexible electronics, their mechanical reliability must be thoroughly investigated to understand their failure mechanisms and lifetimes. Reliability issue caused by bending fatigue, one of the typical operational limitations of flexible electronics, has been studied using various test methodologies; however, electromechanical evaluations which are essential to assess the reliability of electronic devices for flexible applications had not been investigated because the testing method was not established. By employing the in situ bending fatigue test, we has studied the failure mechanism for various conditions and parameters, such as bending strain, fatigue area, film thickness, and lateral dimensions. Moreover, various methods for improving the bending reliability have been developed based on the failure mechanism. Nanostructures such as holes, pores, wires and composites of nanoparticles and nanotubes have been suggested for better reliability. Flexible devices were also investigated to find the potential failures initiated by complex structures under bending fatigue strain. In this review, the recent advances in test methodology, mechanism studies, and practical applications are introduced. Additionally, perspectives including the future advance to stretchable electronics are discussed based on the current achievements in research.

Reliability Issues and Solutions in Flexible Electronics Under Mechanical Fatigue

NASA Astrophysics Data System (ADS)

Yi, Seol-Min; Choi, In-Suk; Kim, Byoung-Joon; Joo, Young-Chang

2018-03-01

Flexible devices are of significant interest due to their potential expansion of the application of smart devices into various fields, such as energy harvesting, biological applications and consumer electronics. Due to the mechanically dynamic operations of flexible electronics, their mechanical reliability must be thoroughly investigated to understand their failure mechanisms and lifetimes. Reliability issue caused by bending fatigue, one of the typical operational limitations of flexible electronics, has been studied using various test methodologies; however, electromechanical evaluations which are essential to assess the reliability of electronic devices for flexible applications had not been investigated because the testing method was not established. By employing the in situ bending fatigue test, we has studied the failure mechanism for various conditions and parameters, such as bending strain, fatigue area, film thickness, and lateral dimensions. Moreover, various methods for improving the bending reliability have been developed based on the failure mechanism. Nanostructures such as holes, pores, wires and composites of nanoparticles and nanotubes have been suggested for better reliability. Flexible devices were also investigated to find the potential failures initiated by complex structures under bending fatigue strain. In this review, the recent advances in test methodology, mechanism studies, and practical applications are introduced. Additionally, perspectives including the future advance to stretchable electronics are discussed based on the current achievements in research.

What is the best method for assessing lower limb force-velocity relationship?

PubMed

Giroux, C; Rabita, G; Chollet, D; Guilhem, G

2015-02-01

This study determined the concurrent validity and reliability of force, velocity and power measurements provided by accelerometry, linear position transducer and Samozino's methods, during loaded squat jumps. 17 subjects performed squat jumps on 2 separate occasions in 7 loading conditions (0-60% of the maximal concentric load). Force, velocity and power patterns were averaged over the push-off phase using accelerometry, linear position transducer and a method based on key positions measurements during squat jump, and compared to force plate measurements. Concurrent validity analyses indicated very good agreement with the reference method (CV=6.4-14.5%). Force, velocity and power patterns comparison confirmed the agreement with slight differences for high-velocity movements. The validity of measurements was equivalent for all tested methods (r=0.87-0.98). Bland-Altman plots showed a lower agreement for velocity and power compared to force. Mean force, velocity and power were reliable for all methods (ICC=0.84-0.99), especially for Samozino's method (CV=2.7-8.6%). Our findings showed that present methods are valid and reliable in different loading conditions and permit between-session comparisons and characterization of training-induced effects. While linear position transducer and accelerometer allow for examining the whole time-course of kinetic patterns, Samozino's method benefits from a better reliability and ease of processing. © Georg Thieme Verlag KG Stuttgart · New York.

Assessment of change in dynamic psychotherapy.

PubMed

Høglend, P; Bøgwald, K P; Amlo, S; Heyerdahl, O; Sørbye, O; Marble, A; Sjaastad, M C; Bentsen, H

2000-01-01

Five scales have been developed to assess changes that are consistent with the therapeutic rationales and procedures of dynamic psychotherapy. Seven raters evaluated 50 patients before and 36 patients again after brief dynamic psychotherapy. A factor analysis indicated that the scales represent a dimension that is discriminable from general symptoms. A summary measure, Dynamic Capacity, was rated with acceptable reliability by a single rater. However, average scores of three raters were needed for good reliability of change ratings. The scales seem to be sufficiently fine-grained to capture statistically and clinically significant changes during brief dynamic psychotherapy.

Scale for positive aspects of caregiving experience: development, reliability, and factor structure.

PubMed

Kate, N; Grover, S; Kulhara, P; Nehra, R

2012-06-01

OBJECTIVE. To develop an instrument (Scale for Positive Aspects of Caregiving Experience [SPACE]) that evaluates positive caregiving experience and assess its psychometric properties. METHODS. Available scales which assess some aspects of positive caregiving experience were reviewed and a 50-item questionnaire with a 5-point rating was constructed. In all, 203 primary caregivers of patients with severe mental disorders were asked to complete the questionnaire. Internal consistency, test-retest reliability, cross-language reliability, split-half reliability, and face validity were evaluated. Principal component factor analysis was run to assess the factorial validity of the scale. RESULTS. The scale developed as part of the study was found to have good internal consistency, test-retest reliability, cross-language reliability, split-half reliability, and face validity. Principal component factor analysis yielded a 4-factor structure, which also had good test-retest reliability and cross-language reliability. There was a strong correlation between the 4 factors obtained. CONCLUSION. The SPACE developed as part of this study has good psychometric properties.

Microorganisms direct identification from blood culture by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

PubMed

Ferreira, L; Sánchez-Juanes, F; Porras-Guerra, I; García-García, M I; García-Sánchez, J E; González-Buitrago, J M; Muñoz-Bellido, J L

2011-04-01

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows a fast and reliable bacterial identification from culture plates. Direct analysis of clinical samples may increase its usefulness in samples in which a fast identification of microorganisms can guide empirical treatment, such as blood cultures (BC). Three hundred and thirty BC, reported as positive by the automated BC incubation device, were processed by conventional methods for BC processing, and by a fast method based on direct MALDI-TOF MS. Three hundred and eighteen of them yield growth on culture plates, and 12 were false positive. The MALDI-TOF MS-based method reported that no peaks were found, or the absence of a reliable identification profile, in all these false positive BC. No mixed cultures were found. Among these 318 BC, we isolated 61 Gram-negatives (GN), 239 Gram-positives (GP) and 18 fungi. Microorganism identifications in GN were coincident with conventional identification, at the species level, in 83.3% of BC and, at the genus level, in 96.6%. In GP, identifications were coincident with conventional identification in 31.8% of BC at the species level, and in 64.8% at the genus level. Fungaemia was not reliably detected by MALDI-TOF. In 18 BC positive for Candida species (eight C. albicans, nine C. parapsilosis and one C. tropicalis), no microorganisms were identified at the species level, and only one (5.6%) was detected at the genus level. The results of the present study show that this fast, MALDI-TOF MS-based method allows bacterial identification directly from presumptively positive BC in a short time (<30 min), with a high accuracy, especially when GN bacteria are involved. © 2010 The Authors. Clinical Microbiology and Infection © 2010 European Society of Clinical Microbiology and Infectious Diseases.

Reliability and Construct Validity of Limits of Stability Test in Adolescents Using a Portable Forceplate System.

PubMed

Alsalaheen, Bara; Haines, Jamie; Yorke, Amy; Broglio, Steven P

2015-12-01

To examine the reliability, convergent, and discriminant validity of the limits of stability (LOS) test to assess dynamic postural stability in adolescents using a portable forceplate system. Cross-sectional reliability observational study. School setting. Adolescents (N=36) completed all measures during the first session. To examine the reliability of the LOS test, a subset of 15 participants repeated the LOS test after 1 week. Not applicable. Outcome measurements included the LOS test, Balance Error Scoring System, Instrumented Balance Error Scoring System, and Modified Clinical Test for Sensory Interaction on Balance. A significant relation was observed among LOS composite scores (r=.36-.87, P<.05). However, no relation was observed between LOS and static balance outcome measurements. The reliability of the LOS composite scores ranged from moderate to good (intraclass correlation coefficient model 2,1=.73-.96). The results suggest that the LOS composite scores provide unique information about dynamic postural stability, and the LOS test completed at 100% of the theoretical limit appeared to be a reliable test of dynamic postural stability in adolescents. Clinicians should use dynamic balance measurement as part of their balance assessment and should not use static balance testing (eg, Balance Error Scoring System) to make inferences about dynamic balance, especially when balance assessment is used to determine rehabilitation outcomes, or when making return to play decisions after injury. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

High effective inverse dynamics modelling for dual-arm robot

NASA Astrophysics Data System (ADS)

Shen, Haoyu; Liu, Yanli; Wu, Hongtao

2018-05-01

To deal with the problem of inverse dynamics modelling for dual arm robot, a recursive inverse dynamics modelling method based on decoupled natural orthogonal complement is presented. In this model, the concepts and methods of Decoupled Natural Orthogonal Complement matrices are used to eliminate the constraint forces in the Newton-Euler kinematic equations, and the screws is used to express the kinematic and dynamics variables. On this basis, the paper has developed a special simulation program with symbol software of Mathematica and conducted a simulation research on the a dual-arm robot. Simulation results show that the proposed method based on decoupled natural orthogonal complement can save an enormous amount of CPU time that was spent in computing compared with the recursive Newton-Euler kinematic equations and the results is correct and reasonable, which can verify the reliability and efficiency of the method.

Generating a Dynamic Synthetic Population – Using an Age-Structured Two-Sex Model for Household Dynamics

PubMed Central

Namazi-Rad, Mohammad-Reza; Mokhtarian, Payam; Perez, Pascal

2014-01-01

Generating a reliable computer-simulated synthetic population is necessary for knowledge processing and decision-making analysis in agent-based systems in order to measure, interpret and describe each target area and the human activity patterns within it. In this paper, both synthetic reconstruction (SR) and combinatorial optimisation (CO) techniques are discussed for generating a reliable synthetic population for a certain geographic region (in Australia) using aggregated- and disaggregated-level information available for such an area. A CO algorithm using the quadratic function of population estimators is presented in this paper in order to generate a synthetic population while considering a two-fold nested structure for the individuals and households within the target areas. The baseline population in this study is generated from the confidentialised unit record files (CURFs) and 2006 Australian census tables. The dynamics of the created population is then projected over five years using a dynamic micro-simulation model for individual- and household-level demographic transitions. This projection is then compared with the 2011 Australian census. A prediction interval is provided for the population estimates obtained by the bootstrapping method, by which the variability structure of a predictor can be replicated in a bootstrap distribution. PMID:24733522

Instrumented Static and Dynamic Balance Assessment after Stroke Using Wii Balance Boards: Reliability and Association with Clinical Tests

PubMed Central

Bower, Kelly J.; McGinley, Jennifer L.; Miller, Kimberly J.; Clark, Ross A.

2014-01-01

Background and Objectives The Wii Balance Board (WBB) is a globally accessible device that shows promise as a clinically useful balance assessment tool. Although the WBB has been found to be comparable to a laboratory-grade force platform for obtaining centre of pressure data, it has not been comprehensively studied in clinical populations. The aim of this study was to investigate the measurement properties of tests utilising the WBB in people after stroke. Methods Thirty individuals who were more than three months post-stroke and able to stand unsupported were recruited from a single outpatient rehabilitation facility. Participants performed standardised assessments incorporating the WBB and customised software (static stance with eyes open and closed, static weight-bearing asymmetry, dynamic mediolateral weight shifting and dynamic sit-to-stand) in addition to commonly employed clinical tests (10 Metre Walk Test, Timed Up and Go, Step Test and Functional Reach) on two testing occasions one week apart. Test-retest reliability and construct validity of the WBB tests were investigated. Results All WBB-based outcomes were found to be highly reliable between testing occasions (ICC  = 0.82 to 0.98). Correlations were poor to moderate between WBB variables and clinical tests, with the strongest associations observed between task-related activities, such as WBB mediolateral weight shifting and the Step Test. Conclusions The WBB, used with customised software, is a reliable and potentially useful tool for the assessment of balance and weight-bearing asymmetry following stroke. Future research is recommended to further investigate validity and responsiveness. PMID:25541939

Instrumented static and dynamic balance assessment after stroke using Wii Balance Boards: reliability and association with clinical tests.

PubMed

Bower, Kelly J; McGinley, Jennifer L; Miller, Kimberly J; Clark, Ross A

2014-01-01

The Wii Balance Board (WBB) is a globally accessible device that shows promise as a clinically useful balance assessment tool. Although the WBB has been found to be comparable to a laboratory-grade force platform for obtaining centre of pressure data, it has not been comprehensively studied in clinical populations. The aim of this study was to investigate the measurement properties of tests utilising the WBB in people after stroke. Thirty individuals who were more than three months post-stroke and able to stand unsupported were recruited from a single outpatient rehabilitation facility. Participants performed standardised assessments incorporating the WBB and customised software (static stance with eyes open and closed, static weight-bearing asymmetry, dynamic mediolateral weight shifting and dynamic sit-to-stand) in addition to commonly employed clinical tests (10 Metre Walk Test, Timed Up and Go, Step Test and Functional Reach) on two testing occasions one week apart. Test-retest reliability and construct validity of the WBB tests were investigated. All WBB-based outcomes were found to be highly reliable between testing occasions (ICC  = 0.82 to 0.98). Correlations were poor to moderate between WBB variables and clinical tests, with the strongest associations observed between task-related activities, such as WBB mediolateral weight shifting and the Step Test. The WBB, used with customised software, is a reliable and potentially useful tool for the assessment of balance and weight-bearing asymmetry following stroke. Future research is recommended to further investigate validity and responsiveness.

Relative Orientation and Position Detections Based on an RGB-D Sensor and Dynamic Cooperation Strategies for Jumping Sensor Nodes Recycling

PubMed Central

Zhang, Jun; Yang, Xi; Song, Guang-Ming; Chen, Tian-Yuan; Zhang, Yong

2015-01-01

This paper presents relative orientation and position detection methods for jumping sensor nodes (JSNs) recycling. The methods are based on motion captures of the JSNs by an RGB-D sensor mounted on a carrier robot and the dynamic cooperation between the carrier and the JSNs. A disc-like label with two different colored sides is mounted on the top of the JSNs. The RGB-D sensor can detect the motion of the label to calculate the orientations and positions of the JSNs and the carrier relative to each other. After the orientations and positions have been detected, the JSNs jump into a cabin mounted on the carrier in dynamic cooperation with the carrier for recycling. The performances of the proposed methods are tested with a prototype system. The results show that the carrier can detect a JSN from up to 2 m away and sense its relative orientation and position successfully. The errors of the JSN’s orientation and position detections relative to the carrier could be reduced to the values smaller than 1° and 1 cm, respectively, by using the dynamic cooperation strategies. The proposed methods in this paper could also be used for other kinds of mobile sensor nodes and multi-robot systems. PMID:26393589

A reliable unipedal stance test for the assessment of balance using a force platform.

PubMed

Ponce-González, J G; Sanchis-Moysi, J; González-Henriquez, J J; Arteaga-Ortiz, R; Calbet, J A L; Dorado, C

2014-02-01

The aim was to develop a unipedal stance test for the assessment of balance using a force platform. A single-leg balance test was conducted in 23 students (mean ± SD) age: 23 ± 3 years) in a standard position limiting the movement of the arms and non-supporting leg. Six attempts, with both the jumping (JL) and the contralateral leg (CL), were performed under 3 conditions: 1) eyes opened; 2) eyes closed; 3) eyes opened and executing a precision task. The same protocol was repeated two-week apart. The mean and the best result of the six attempts performed each day were taken as representative of balance. The speed of the centre of pressure (CP-Speed) showed excellent reliability for the "best result" analysis in all tests (ICCs 0.87-0.97), except in the test with the eyes closed performed on the CL (ICC<0.4). The CP-Speed had better reliability with the "best result" than with the "mean result" analysis (P<0.05), whilst no significant differences were observed between the JL and the CL (P=0.71 and P=0.96 for mean and best results analysis, respectively). A lower dispersion in the Bland and Altman graph was observed with the eyes opened than closed, and the dynamic test. The single-leg stance balance test proposed is a reliable method to assess balance, especially when performed in a static position, with the eyes opened and using the best result of six attempts as reference, independently of the stance leg.

Linear and evolutionary polynomial regression models to forecast coastal dynamics: Comparison and reliability assessment

NASA Astrophysics Data System (ADS)

Bruno, Delia Evelina; Barca, Emanuele; Goncalves, Rodrigo Mikosz; de Araujo Queiroz, Heithor Alexandre; Berardi, Luigi; Passarella, Giuseppe

2018-01-01

In this paper, the Evolutionary Polynomial Regression data modelling strategy has been applied to study small scale, short-term coastal morphodynamics, given its capability for treating a wide database of known information, non-linearly. Simple linear and multilinear regression models were also applied to achieve a balance between the computational load and reliability of estimations of the three models. In fact, even though it is easy to imagine that the more complex the model, the more the prediction improves, sometimes a "slight" worsening of estimations can be accepted in exchange for the time saved in data organization and computational load. The models' outcomes were validated through a detailed statistical, error analysis, which revealed a slightly better estimation of the polynomial model with respect to the multilinear model, as expected. On the other hand, even though the data organization was identical for the two models, the multilinear one required a simpler simulation setting and a faster run time. Finally, the most reliable evolutionary polynomial regression model was used in order to make some conjecture about the uncertainty increase with the extension of extrapolation time of the estimation. The overlapping rate between the confidence band of the mean of the known coast position and the prediction band of the estimated position can be a good index of the weakness in producing reliable estimations when the extrapolation time increases too much. The proposed models and tests have been applied to a coastal sector located nearby Torre Colimena in the Apulia region, south Italy.

Studies of New Fused Benzazepine as Selective Dopamine D3 Receptor Antagonists Using 3D-QSAR, Molecular Docking and Molecular Dynamics

PubMed Central

Liu, Jing; Li, Yan; Zhang, Shuwei; Xiao, Zhengtao; Ai, Chunzhi

2011-01-01

In recent years, great interest has been paid to the development of compounds with high selectivity for central dopamine (DA) D3 receptors, an interesting therapeutic target in the treatment of different neurological disorders. In the present work, based on a dataset of 110 collected benzazepine (BAZ) DA D3 antagonists with diverse kinds of structures, a variety of in silico modeling approaches, including comparative molecular field analysis (CoMFA), comparative similarity indices analysis (CoMSIA), homology modeling, molecular docking and molecular dynamics (MD) were carried out to reveal the requisite 3D structural features for activity. Our results show that both the receptor-based (Q2 = 0.603, R2ncv = 0.829, R2pre = 0.690, SEE = 0.316, SEP = 0.406) and ligand-based 3D-QSAR models (Q2 = 0.506, R2ncv =0.838, R2pre = 0.794, SEE = 0.316, SEP = 0.296) are reliable with proper predictive capacity. In addition, a combined analysis between the CoMFA, CoMSIA contour maps and MD results with a homology DA receptor model shows that: (1) ring-A, position-2 and R3 substituent in ring-D are crucial in the design of antagonists with higher activity; (2) more bulky R1 substituents (at position-2 of ring-A) of antagonists may well fit in the binding pocket; (3) hydrophobicity represented by MlogP is important for building satisfactory QSAR models; (4) key amino acids of the binding pocket are CYS101, ILE105, LEU106, VAL151, PHE175, PHE184, PRO254 and ALA251. To our best knowledge, this work is the first report on 3D-QSAR modeling of the new fused BAZs as DA D3 antagonists. These results might provide information for a better understanding of the mechanism of antagonism and thus be helpful in designing new potent DA D3 antagonists. PMID:21541053

Studies of new fused benzazepine as selective dopamine D3 receptor antagonists using 3D-QSAR, molecular docking and molecular dynamics.

PubMed

Liu, Jing; Li, Yan; Zhang, Shuwei; Xiao, Zhengtao; Ai, Chunzhi

2011-02-18

In recent years, great interest has been paid to the development of compounds with high selectivity for central dopamine (DA) D3 receptors, an interesting therapeutic target in the treatment of different neurological disorders. In the present work, based on a dataset of 110 collected benzazepine (BAZ) DA D3 antagonists with diverse kinds of structures, a variety of in silico modeling approaches, including comparative molecular field analysis (CoMFA), comparative similarity indices analysis (CoMSIA), homology modeling, molecular docking and molecular dynamics (MD) were carried out to reveal the requisite 3D structural features for activity. Our results show that both the receptor-based (Q(2) = 0.603, R(2) (ncv) = 0.829, R(2) (pre) = 0.690, SEE = 0.316, SEP = 0.406) and ligand-based 3D-QSAR models (Q(2) = 0.506, R(2) (ncv) =0.838, R(2) (pre) = 0.794, SEE = 0.316, SEP = 0.296) are reliable with proper predictive capacity. In addition, a combined analysis between the CoMFA, CoMSIA contour maps and MD results with a homology DA receptor model shows that: (1) ring-A, position-2 and R(3) substituent in ring-D are crucial in the design of antagonists with higher activity; (2) more bulky R(1) substituents (at position-2 of ring-A) of antagonists may well fit in the binding pocket; (3) hydrophobicity represented by MlogP is important for building satisfactory QSAR models; (4) key amino acids of the binding pocket are CYS101, ILE105, LEU106, VAL151, PHE175, PHE184, PRO254 and ALA251. To our best knowledge, this work is the first report on 3D-QSAR modeling of the new fused BAZs as DA D3 antagonists. These results might provide information for a better understanding of the mechanism of antagonism and thus be helpful in designing new potent DA D3 antagonists.

Comparative organochlorine accumulation in two ecologically similar shark species (Carcharodon carcharias and Carcharhinus obscurus) with divergent uptake based on different life history.

PubMed

Beaudry, Marina C; Hussey, Nigel E; McMeans, Bailey C; McLeod, Anne M; Wintner, Sabine P; Cliff, Geremy; Dudley, Sheldon F J; Fisk, Aaron T

2015-09-01

Trophic position and body mass are traits commonly used to predict organochlorine burdens. Sharks, however, have a variety of feeding and life history strategies and metabolize lipid uniquely. Because of this diversity, and the lipid-association of organochlorines, the dynamics of organochlorine accumulation in sharks may be predicted ineffectively by stable isotope-derived trophic position and body mass, as is typical for other taxa. The present study compared ontogenetic organochlorine profiles in the dusky shark (Carcharhinus obscurus) and white shark (Carcharodon carcharias), which differ in metabolic thermoregulation and trophic position throughout their ontogeny. Although greater organochlorine concentrations were observed in the larger bodied and higher trophic position white shark (e.g., p,p'-dichlorodiphenyldichloroethylene: 20.2 ± 2.7 ng/g vs 9.3 ± 2.2 ng/g in the dusky shark), slopes of growth-dilution corrected concentrations with age were equal to those of the dusky shark. Similar ontogenetic trophic position increases in both species, less frequent white shark seal predation than previously assumed, or inaccurate species-specific growth parameters are possible explanations. Inshore habitat use (indicated by δ(13)C values) and mass were important predictors in white and dusky sharks, respectively, of both overall compound profiles and select organochlorine concentrations. The present study clarified understanding of trophic position and body mass as reliable predictors of interspecific organochlorine accumulation in sharks, whereas regional endothermy and diet shifting were shown to have less impact on overall rates of accumulation. © 2015 SETAC.

Quantitative assessment of human motion using video motion analysis

NASA Technical Reports Server (NTRS)

Probe, John D.

1993-01-01

In the study of the dynamics and kinematics of the human body a wide variety of technologies has been developed. Photogrammetric techniques are well documented and are known to provide reliable positional data from recorded images. Often these techniques are used in conjunction with cinematography and videography for analysis of planar motion, and to a lesser degree three-dimensional motion. Cinematography has been the most widely used medium for movement analysis. Excessive operating costs and the lag time required for film development, coupled with recent advances in video technology, have allowed video based motion analysis systems to emerge as a cost effective method of collecting and analyzing human movement. The Anthropometric and Biomechanics Lab at Johnson Space Center utilizes the video based Ariel Performance Analysis System (APAS) to develop data on shirtsleeved and space-suited human performance in order to plan efficient on-orbit intravehicular and extravehicular activities. APAS is a fully integrated system of hardware and software for biomechanics and the analysis of human performance and generalized motion measurement. Major components of the complete system include the video system, the AT compatible computer, and the proprietary software.

Finite element analysis of displacement actuator based on giant magnetostrictive thin film

NASA Astrophysics Data System (ADS)

Yu, Shaopeng; Wang, Bowen; Zhang, Changgeng; Cui, Baozhi

2018-05-01

With the rapid development of science and technology, mechanical and electrical equipment become more and more miniature. In order to achieve precise control in less than 1cm3, the giant magnetostrictive thin film has become a research hotspot. The micro displacement actuator with planar and arc film is designed by the dynamic coupling model based on J-A model and magneto-mechanical effect method which is proposed in this paper. The different structure and thickness of films are analyzed by COMSOL Multiphysics software when the current flows through driving coil. After comparing the simulation results with the test ones, it can be seen that the coupling model is accurate and the structure is reliable. At the same time, MATLAB is used to fit the current density-displacement curve and higher order equation is obtained, and then the feasibility of design can be verified. The actuator with arc structure had advantages of small volume, fast response, high precision, easy integration, etc., which has a broad application prospect in the field of vibration control, micro positioning, robot and so on.

Objective-lens-free Fiber-based Position Detection with Nanometer Resolution in a Fiber Optical Trapping System.

PubMed

Ti, Chaoyang; Ho-Thanh, Minh-Tri; Wen, Qi; Liu, Yuxiang

2017-10-13

Position detection with high accuracy is crucial for force calibration of optical trapping systems. Most existing position detection methods require high-numerical-aperture objective lenses, which are bulky, expensive, and difficult to miniaturize. Here, we report an affordable objective-lens-free, fiber-based position detection scheme with 2 nm spatial resolution and 150 MHz bandwidth. This fiber based detection mechanism enables simultaneous trapping and force measurements in a compact fiber optical tweezers system. In addition, we achieved more reliable signal acquisition with less distortion compared with objective based position detection methods, thanks to the light guiding in optical fibers and small distance between the fiber tips and trapped particle. As a demonstration of the fiber based detection, we used the fiber optical tweezers to apply a force on a cell membrane and simultaneously measure the cellular response.

Hybrid learning in signalling games

NASA Astrophysics Data System (ADS)

Barrett, Jeffrey A.; Cochran, Calvin T.; Huttegger, Simon; Fujiwara, Naoki

2017-09-01

Lewis-Skyrms signalling games have been studied under a variety of low-rationality learning dynamics. Reinforcement dynamics are stable but slow and prone to evolving suboptimal signalling conventions. A low-inertia trial-and-error dynamical like win-stay/lose-randomise is fast and reliable at finding perfect signalling conventions but unstable in the context of noise or agent error. Here we consider a low-rationality hybrid of reinforcement and win-stay/lose-randomise learning that exhibits the virtues of both. This hybrid dynamics is reliable, stable and exceptionally fast.

RICA: a reliable and image configurable arena for cyborg bumblebee based on CAN bus.

PubMed

Gong, Fan; Zheng, Nenggan; Xue, Lei; Xu, Kedi; Zheng, Xiaoxiang

2014-01-01

In this paper, we designed a reliable and image configurable flight arena, RICA, for developing cyborg bumblebees. To meet the spatial and temporal requirements of bumblebees, the Controller Area Network (CAN) bus is adopted to interconnect the LED display modules to ensure the reliability and real-time performance of the arena system. Easily-configurable interfaces on a desktop computer implemented by python scripts are provided to transmit the visual patterns to the LED distributor online and configure RICA dynamically. The new arena system will be a power tool to investigate the quantitative relationship between the visual inputs and induced flight behaviors and also will be helpful to the visual-motor research in other related fields.

Application of reliability-centered-maintenance to BWR ECCS motor operator valve performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feltus, M.A.; Choi, Y.A.

1993-01-01

This paper describes the application of reliability-centered maintenance (RCM) methods to plant probabilistic risk assessment (PRA) and safety analyses for four boiling water reactor emergency core cooling systems (ECCSs): (1) high-pressure coolant injection (HPCI); (2) reactor core isolation cooling (RCIC); (3) residual heat removal (RHR); and (4) core spray systems. Reliability-centered maintenance is a system function-based technique for improving a preventive maintenance program that is applied on a component basis. Those components that truly affect plant function are identified, and maintenance tasks are focused on preventing their failures. The RCM evaluation establishes the relevant criteria that preserve system function somore » that an RCM-focused approach can be flexible and dynamic.« less

Software development predictors, error analysis, reliability models and software metric analysis

NASA Technical Reports Server (NTRS)

Basili, Victor

1983-01-01

The use of dynamic characteristics as predictors for software development was studied. It was found that there are some significant factors that could be useful as predictors. From a study on software errors and complexity, it was shown that meaningful results can be obtained which allow insight into software traits and the environment in which it is developed. Reliability models were studied. The research included the field of program testing because the validity of some reliability models depends on the answers to some unanswered questions about testing. In studying software metrics, data collected from seven software engineering laboratory (FORTRAN) projects were examined and three effort reporting accuracy checks were applied to demonstrate the need to validate a data base. Results are discussed.

Verification and Validation of the New Dynamic Mooring Modules Available in FAST v8: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wendt, Fabian; Robertson, Amy; Jonkman, Jason

2016-08-01

The open-source aero-hydro-servo-elastic wind turbine simulation software, FAST v8, was recently coupled to two newly developed mooring dynamics modules: MoorDyn and FEAMooring. MoorDyn is a lumped-mass-based mooring dynamics module developed by the University of Maine, and FEAMooring is a finite-element-based mooring dynamics module developed by Texas A&M University. This paper summarizes the work performed to verify and validate these modules against other mooring models and measured test data to assess their reliability and accuracy. The quality of the fairlead load predictions by the open-source mooring modules MoorDyn and FEAMooring appear to be largely equivalent to what is predicted by themore » commercial tool OrcaFlex. Both mooring dynamic model predictions agree well with the experimental data, considering the given limitations in the accuracy of the platform hydrodynamic load calculation and the quality of the measurement data.« less

Verification and Validation of the New Dynamic Mooring Modules Available in FAST v8

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wendt, Fabian F.; Andersen, Morten T.; Robertson, Amy N.

2016-07-01

The open-source aero-hydro-servo-elastic wind turbine simulation software, FAST v8, was recently coupled to two newly developed mooring dynamics modules: MoorDyn and FEAMooring. MoorDyn is a lumped-mass-based mooring dynamics module developed by the University of Maine, and FEAMooring is a finite-element-based mooring dynamics module developed by Texas A&M University. This paper summarizes the work performed to verify and validate these modules against other mooring models and measured test data to assess their reliability and accuracy. The quality of the fairlead load predictions by the open-source mooring modules MoorDyn and FEAMooring appear to be largely equivalent to what is predicted by themore » commercial tool OrcaFlex. Both mooring dynamic model predictions agree well with the experimental data, considering the given limitations in the accuracy of the platform hydrodynamic load calculation and the quality of the measurement data.« less

Trajectory Specification for Automation of Terminal Air Traffic Control

NASA Technical Reports Server (NTRS)

Paielli, Russell A.

2016-01-01

"Trajectory specification" is the explicit bounding and control of aircraft tra- jectories such that the position at each point in time is constrained to a precisely defined volume of space. The bounding space is defined by cross-track, along-track, and vertical tolerances relative to a reference trajectory that specifies position as a function of time. The tolerances are dynamic and will be based on the aircraft nav- igation capabilities and the current traffic situation. A standard language will be developed to represent these specifications and to communicate them by datalink. Assuming conformance, trajectory specification can guarantee safe separation for an arbitrary period of time even in the event of an air traffic control (ATC) sys- tem or datalink failure, hence it can help to achieve the high level of safety and reliability needed for ATC automation. As a more proactive form of ATC, it can also maximize airspace capacity and reduce the reliance on tactical backup systems during normal operation. It applies to both enroute airspace and the terminal area around airports, but this paper focuses on arrival spacing in the terminal area and presents ATC algorithms and software for achieving a specified delay of runway arrival time.

Error measuring system of rotary Inductosyn

NASA Astrophysics Data System (ADS)

Liu, Chengjun; Zou, Jibin; Fu, Xinghe

2008-10-01

The inductosyn is a kind of high-precision angle-position sensor. It has important applications in servo table, precision machine tool and other products. The precision of inductosyn is calibrated by its error. It's an important problem about the error measurement in the process of production and application of the inductosyn. At present, it mainly depends on the method of artificial measurement to obtain the error of inductosyn. Therefore, the disadvantages can't be ignored such as the high labour intensity of the operator, the occurrent error which is easy occurred and the poor repeatability, and so on. In order to solve these problems, a new automatic measurement method is put forward in this paper which based on a high precision optical dividing head. Error signal can be obtained by processing the output signal of inductosyn and optical dividing head precisely. When inductosyn rotating continuously, its zero position error can be measured dynamically, and zero error curves can be output automatically. The measuring and calculating errors caused by man-made factor can be overcome by this method, and it makes measuring process more quickly, exactly and reliably. Experiment proves that the accuracy of error measuring system is 1.1 arc-second (peak - peak value).

Trajectory Specification for Terminal Air Traffic: Pairwise Conflict Detection and Resolution

NASA Technical Reports Server (NTRS)

Paielli, Russ; Erzberger, Heinz

2017-01-01

Trajectory specification is the explicit bounding and control of aircraft trajectories such that the position at each point in time is constrained to a precisely defined volume of space. The bounding space is defined by cross-track, along-track, and vertical tolerances relative to a reference trajectory that specifies position as a function of time. The tolerances are dynamic and will be based on the aircraft navigation capabilities and the current traffic situation. A standard language will be developed to represent these specifications and to communicate them by datalink. Assuming conformance, trajectory specification can guarantee safe separation for an arbitrary period of time even in the event of an air traffic control (ATC) system or datalink failure, hence it can help to achieve the high level of safety and reliability needed for ATC automation. As a more proactive form of ATC, it can also maximize airspace capacity and reduce the reliance on tactical backup systems during normal operation. It applies to both enroute airspace and the terminal area around airports, but this paper focuses on the terminal area and presents algorithms and software for spacing arrivals and deconflicting both arrivals and departures.

Comparison of central HER2 testing with quantitative total HER2 expression and HER2 homodimer measurements using a novel proximity-based assay.

PubMed

Huang, Weidong; Reinholz, Monica; Weidler, Jodi; Yolanda, Lie; Paquet, Agnes; Whitcomb, Jeannette; Lingle, Wilma; Jenkins, Robert B; Chen, Beiyun; Larson, Jeffrey S; Tan, Yuping; Sherwood, Thomas; Bates, Michael; Perez, Edith A

2010-08-01

The accuracy and reliability of immunohistochemical analysis and in situ hybridization for the assessment of HER2 status remains a subject of debate. We developed a novel assay (HERmark Breast Cancer Assay, Monogram Biosciences, South San Francisco, CA) that provides precise quantification of total HER2 protein expression (H2T) and HER2 homodimers (H2D) in formalin-fixed, paraffin-embedded tissue specimens. H2T and H2D results of 237 breast cancers were compared with those of immunohistochemical studies and fluorescence in situ hybridization (FISH) centrally performed at the Mayo Clinic, Rochester, MN. H2T described a continuum across a wide dynamic range ( approximately 2.5 log). Excluding the equivocal cases, HERmark showed 98% concordance with immunohistochemical studies for positive and negative assay values. For the 94 immunohistochemically equivocal cases, 67% and 39% concordance values were observed between HERmark and FISH for positive and negative assay values, respectively. Polysomy 17 in the absence of HER2 gene amplification did not result in HER2 overexpression as evaluated quantitatively using the HERmark assay.

Development of a reliable simulation-based test for diagnostic abdominal ultrasound with a pass/fail standard usable for mastery learning.

PubMed

Østergaard, Mia L; Nielsen, Kristina R; Albrecht-Beste, Elisabeth; Konge, Lars; Nielsen, Michael B

2018-01-01

This study aimed to develop a test with validity evidence for abdominal diagnostic ultrasound with a pass/fail-standard to facilitate mastery learning. The simulator had 150 real-life patient abdominal scans of which 15 cases with 44 findings were selected, representing level 1 from The European Federation of Societies for Ultrasound in Medicine and Biology. Four groups of experience levels were constructed: Novices (medical students), trainees (first-year radiology residents), intermediates (third- to fourth-year radiology residents) and advanced (physicians with ultrasound fellowship). Participants were tested in a standardized setup and scored by two blinded reviewers prior to an item analysis. The item analysis excluded 14 diagnoses. Both internal consistency (Cronbach's alpha 0.96) and inter-rater reliability (0.99) were good and there were statistically significant differences (p < 0.001) between all four groups, except the intermediate and advanced groups (p = 1.0). There was a statistically significant correlation between experience and test scores (Pearson's r = 0.82, p < 0.001). The pass/fail-standard failed all novices (no false positives) and passed all advanced (no false negatives). All intermediate participants and six out of 14 trainees passed. We developed a test for diagnostic abdominal ultrasound with solid validity evidence and a pass/fail-standard without any false-positive or false-negative scores. • Ultrasound training can benefit from competency-based education based on reliable tests. • This simulation-based test can differentiate between competency levels of ultrasound examiners. • This test is suitable for competency-based education, e.g. mastery learning. • We provide a pass/fail standard without false-negative or false-positive scores.

On the integral use of foundational concepts in verifying validity during skull-photo superimposition.

PubMed

Jayaprakash, Paul T

2017-09-01

Often cited reliability test on video superimposition method integrated scaling face-images in relation to skull-images, tragus-auditory meatus relationship in addition to exocanthion-Whitnall's tubercle relationship when orientating the skull-image and wipe mode imaging in addition to mix mode imaging when obtaining skull-face image overlay and evaluating the goodness of match. However, a report that found higher false positive matches in computer assisted superimposition method transited from the above foundational concepts and relied on images of unspecified sizes that are lesser than 'life-size', frontal plane landmarks in the skull- and face- images alone for orientating the skull-image and mix images alone for evaluating the goodness of match. Recently, arguing the use of 'life-size' images as 'archaic', the authors who tested the reliability in the computer assisted superimposition method have denied any method transition. This article describes that the use of images of unspecified sizes at lesser than 'life-size' eliminates the only possibility to quantify parameters during superimposition which alone enables dynamic skull orientation when overlaying a skull-image with a face-image in an anatomically acceptable orientation. The dynamic skull orientation process mandatorily requires aligning the tragus in the 2D face-image with the auditory meatus in the 3D skull-image for anatomically orientating the skull-image in relation to the posture in the face-image, a step not mentioned by the authors describing the computer assisted superimposition method. Furthermore, mere reliance on mix type images during image overlay eliminates the possibility to assess the relationship between the leading edges of the skull- and face-image outlines as also specific area match among the corresponding craniofacial organs during superimposition. Indicating the possibility of increased false positive matches as a consequence of the above method transitions, the need for testing the reliability in the superimposition method adopting concepts that are considered safe is stressed. Copyright © 2017 Elsevier B.V. All rights reserved.

Reliability and mass analysis of dynamic power conversion systems with parallel of standby redundancy

NASA Technical Reports Server (NTRS)

Juhasz, A. J.; Bloomfield, H. S.

1985-01-01

A combinatorial reliability approach is used to identify potential dynamic power conversion systems for space mission applications. A reliability and mass analysis is also performed, specifically for a 100 kWe nuclear Brayton power conversion system with parallel redundancy. Although this study is done for a reactor outlet temperature of 1100K, preliminary system mass estimates are also included for reactor outlet temperatures ranging up to 1500 K.

Augmented reality and dynamic infrared thermography for perforator mapping in the anterolateral thigh.

PubMed

Cifuentes, Ignacio Javier; Dagnino, Bruno Leonardo; Salisbury, María Carolina; Perez, María Eliana; Ortega, Claudia; Maldonado, Daniela

2018-05-01

Dynamic infrared thermography (DIRT) has been used for the preoperative mapping of cutaneous perforators. This technique has shown a positive correlation with intraoperative findings. Our aim was to evaluate the accuracy of perforator mapping with DIRT and augmented reality using a portable projector. For this purpose, three volunteers had both of their anterolateral thighs assessed for the presence and location of cutaneous perforators using DIRT. The obtained image of these "hotspots" was projected back onto the thigh and the presence of Doppler signals within a 10-cm diameter from the midpoint between the lateral patella and the anterior superior iliac spine was assessed using a handheld Doppler device. Hotspots were identified in all six anterolateral thighs and were successfully projected onto the skin. The median number of perforators identified within the area of interest was 5 (range, 3-8) and the median time needed to identify them was 3.5 minutes (range, 3.3-4.0 minutes). Every hotspot was correlated to a Doppler sound signal. In conclusion, augmented reality can be a reliable method for transferring the location of perforators identified by DIRT onto the thigh, facilitating its assessment and yielding a reliable map of potential perforators for flap raising.

Magnetic suspension and balance systems (MSBSs)

NASA Technical Reports Server (NTRS)

Britcher, Colin P.; Kilgore, Robert A.

1987-01-01

The problems of wind tunnel testing are outlined, with attention given to the problems caused by mechanical support systems, such as support interference, dynamic-testing restrictions, and low productivity. The basic principles of magnetic suspension are highlighted, along with the history of magnetic suspension and balance systems. Roll control, size limitations, high angle of attack, reliability, position sensing, and calibration are discussed among the problems and limitations of the existing magnetic suspension and balance systems. Examples of the existing systems are presented, and design studies for future systems are outlined. Problems specific to large-scale magnetic suspension and balance systems, such as high model loads, requirements for high-power electromagnets, high-capacity power supplies, highly sophisticated control systems and position sensors, and high costs are assessed.

Reliability of corneal dynamic scheimpflug analyser measurements in virgin and post-PRK eyes.

PubMed

Chen, Xiangjun; Stojanovic, Aleksandar; Hua, Yanjun; Eidet, Jon Roger; Hu, Di; Wang, Jingting; Utheim, Tor Paaske

2014-01-01

To determine the measurement reliability of CorVis ST, a dynamic Scheimpflug analyser, in virgin and post-photorefractive keratectomy (PRK) eyes and compare the results between these two groups. Forty virgin eyes and 42 post-PRK eyes underwent CorVis ST measurements performed by two technicians. Repeatability was evaluated by comparing three consecutive measurements by technician A. Reproducibility was determined by comparing the first measurement by technician A with one performed by technician B. Intraobserver and interobserver intraclass correlation coefficients (ICCs) were calculated. Univariate analysis of covariance (ANCOVA) was used to compare measured parameters between virgin and post-PRK eyes. The intraocular pressure (IOP), central corneal thickness (CCT) and 1st applanation time demonstrated good intraobserver repeatability and interobserver reproducibility (ICC ≧ 0.90) in virgin and post-PRK eyes. The deformation amplitude showed a good or close to good repeatability and reproducibility in both groups (ICC ≧ 0.88). The CCT correlated positively with 1st applanation time (r = 0.437 and 0.483, respectively, p<0.05) and negatively with deformation amplitude (r = -0.384 and -0.375, respectively, p<0.05) in both groups. Compared to post-PRK eyes, virgin eyes showed longer 1st applanation time (7.29 ± 0.21 vs. 6.96 ± 0.17 ms, p<0.05) and lower deformation amplitude (1.06 ± 0.07 vs. 1.17 ± 0.08 mm, p < 0.05). CorVis ST demonstrated reliable measurements for CCT, IOP, and 1st applanation time, as well as relatively reliable measurement for deformation amplitude in both virgin and post-PRK eyes. There were differences in 1st applanation time and deformation amplitude between virgin and post-PRK eyes, which may reflect corneal biomechanical changes occurring after the surgery in the latter.

Women's Liberation Scale (WLS): A Measure of Attitudes Toward Positions Advocated by Women's Groups.

ERIC Educational Resources Information Center

Goldberg, Carlos

The Women's Liberation Scale (WLS) is a 14-item, Likert-type scale designed to measure attitudes toward positions advocated by women's groups. The WLS and its four-alternative response schema is presented, along with descriptive statistics of scores based on male and female college samples. Reliability and validity measures are reported, and the…

Detecting similarities among distant homologous proteins by comparison of domain flexibilities.

PubMed

Pandini, Alessandro; Mauri, Giancarlo; Bordogna, Annalisa; Bonati, Laura

2007-06-01

Aim of this work is to assess the informativeness of protein dynamics in the detection of similarities among distant homologous proteins. To this end, an approach to perform large-scale comparisons of protein domain flexibilities is proposed. CONCOORD is confirmed as a reliable method for fast conformational sampling. The root mean square fluctuation of alpha carbon positions in the essential dynamics subspace is employed as a measure of local flexibility and a synthetic index of similarity is presented. The dynamics of a large collection of protein domains from ASTRAL/SCOP40 is analyzed and the possibility to identify relationships, at both the family and the superfamily levels, on the basis of the dynamical features is discussed. The obtained picture is in agreement with the SCOP classification, and furthermore suggests the presence of a distinguishable familiar trend in the flexibility profiles. The results support the complementarity of the dynamical and the structural information, suggesting that information from dynamics analysis can arise from functional similarities, often partially hidden by a static comparison. On the basis of this first test, flexibility annotation can be expected to help in automatically detecting functional similarities otherwise unrecoverable.

Efficient digital implementation of a conductance-based globus pallidus neuron and the dynamics analysis

NASA Astrophysics Data System (ADS)

Yang, Shuangming; Wei, Xile; Deng, Bin; Liu, Chen; Li, Huiyan; Wang, Jiang

2018-03-01

Balance between biological plausibility of dynamical activities and computational efficiency is one of challenging problems in computational neuroscience and neural system engineering. This paper proposes a set of efficient methods for the hardware realization of the conductance-based neuron model with relevant dynamics, targeting reproducing the biological behaviors with low-cost implementation on digital programmable platform, which can be applied in wide range of conductance-based neuron models. Modified GP neuron models for efficient hardware implementation are presented to reproduce reliable pallidal dynamics, which decode the information of basal ganglia and regulate the movement disorder related voluntary activities. Implementation results on a field-programmable gate array (FPGA) demonstrate that the proposed techniques and models can reduce the resource cost significantly and reproduce the biological dynamics accurately. Besides, the biological behaviors with weak network coupling are explored on the proposed platform, and theoretical analysis is also made for the investigation of biological characteristics of the structured pallidal oscillator and network. The implementation techniques provide an essential step towards the large-scale neural network to explore the dynamical mechanisms in real time. Furthermore, the proposed methodology enables the FPGA-based system a powerful platform for the investigation on neurodegenerative diseases and real-time control of bio-inspired neuro-robotics.

R&D Investment in New Technology-Based Firms: Strategic and Entrepreneurial Dynamics and the Impact of Universities

ERIC Educational Resources Information Center

Lynskey, Michael J.

2016-01-01

This article examines how two core factors--strategic and entrepreneurial dynamics--influence research and development (R&D) investment in new technology-based firms (NTBFs) using data from a questionnaire survey conducted in Japan. Among the strategic dynamics, it is found that joint R&D projects with universities have a positive,…

A compact ball screw based electromagnetic energy harvester for railroad application

NASA Astrophysics Data System (ADS)

Pan, Yu; Lin, Teng; Liu, Cheng; Yu, Jie; Zuo, Jianyong; Zuo, Lei

2018-03-01

To enable the smart technologies, such as the positive train controls, rail damage detection and track health monitoring on the railroad side, the electricity is required and in needed. In this paper, we proposed a novel ball-screw based electromagnetic energy harvester for railway track with mechanical-motion-rectifier (MMR) mechanism, to harvest the energy that usually dissipated and wasted during train induced track vibration. Ball screw based design reduces backlash during motion transmission, and MMR nonlinear characteristics with one way clutches makes the harvester convert the bi-direction track vibration into a generator's unidirectional rotation, which improves the transmission reliability and increases the energy harvesting efficiency. A systematic model combining train-rail-harvester was established to analyze the dynamic characteristic of the proposed railway energy, and lab and in-field tests were carried out to experimentally characterize the proposed energy harvester. In lab bench test showed the proposed harvester reached a 70% mechanical efficiency with a high sensitivity to the environment vibration. In filed test showed that a peak 7.8W phase power was achieved when a two marshaling type A metro train passed by with a 30 km/h.

A phylogenetic comparison of urease-positive thermophilic Campylobacter (UPTC) and urease-negative (UN) C. lari.

PubMed

Hirayama, Junichi; Tazumi, Akihiro; Hayashi, Kyohei; Tasaki, Erina; Kuribayashi, Takashi; Moore, John E; Millar, Beverley C; Matsuda, Motoo

2011-06-01

In the present study, the reliability of full-length gene sequence information for several genes including 16S rRNA was examined, for the discrimination of the two representative Campylobacter lari taxa, namely urease-negative (UN) C. lari and urease-positive thermophilic Campylobacter (UPTC). As previously described, 16S rRNA gene sequence are not reliable for the molecular discrimination of UN C. lari from UPTC organisms employing both the unweighted pair group method using arithmetic means analysis (UPGMA) and neighbor joining (NJ) methods. In addition, three composite full-length gene sequences (ciaB, flaC and vacJ) out of seven gene loci examined were reliable for discrimination employing dendrograms constructed by the UPGMA method. In addition, all the dendrograms of the NJ phylogenetic trees constructed based on the nine gene information were not reliable for the discrimination. Three composite full-length gene sequences (ciaB, flaC and vacJ) were reliable for the molecular discrimination between UN C. lari and UPTC organisms employing the UPGMA method, as well as among four thermophilic Campylobacter species. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On-board adaptive model for state of charge estimation of lithium-ion batteries based on Kalman filter with proportional integral-based error adjustment

NASA Astrophysics Data System (ADS)

Wei, Jingwen; Dong, Guangzhong; Chen, Zonghai

2017-10-01

With the rapid development of battery-powered electric vehicles, the lithium-ion battery plays a critical role in the reliability of vehicle system. In order to provide timely management and protection for battery systems, it is necessary to develop a reliable battery model and accurate battery parameters estimation to describe battery dynamic behaviors. Therefore, this paper focuses on an on-board adaptive model for state-of-charge (SOC) estimation of lithium-ion batteries. Firstly, a first-order equivalent circuit battery model is employed to describe battery dynamic characteristics. Then, the recursive least square algorithm and the off-line identification method are used to provide good initial values of model parameters to ensure filter stability and reduce the convergence time. Thirdly, an extended-Kalman-filter (EKF) is applied to on-line estimate battery SOC and model parameters. Considering that the EKF is essentially a first-order Taylor approximation of battery model, which contains inevitable model errors, thus, a proportional integral-based error adjustment technique is employed to improve the performance of EKF method and correct model parameters. Finally, the experimental results on lithium-ion batteries indicate that the proposed EKF with proportional integral-based error adjustment method can provide robust and accurate battery model and on-line parameter estimation.

Investigations into the Instructional Process: X. Report of the DPA Helsinki, Phase One.

ERIC Educational Resources Information Center

Koskenniemi, Matti; Komulainen, Erkki

The research reported in this document represents efforts to search for the structure and dynamics of the instructional process itself. Without reliable knowledge of these basic facts, improvement of teacher education and the guidance of teachers would remain based on unsystematic experiences and speculation. In order to penetrate the structure…

Force Project Technology Presentation to the NRCC

DTIC Science & Technology

2014-02-04

Functional Bridge components Smart Odometer Adv Pretreatment Smart Bridge Multi-functional Gap Crossing Fuel Automated Tracking System Adv...comprehensive matrix of candidate composite material systems and textile reinforcement architectures via modeling/analyses and testing. Product(s...Validated Dynamic Modeling tool based on parametric study using material models to reliably predict the textile mechanics of the hose

Gearbox Reliability Collaborative Research | Wind | NREL

Science.gov Websites

inception, the Gearbox Reliability Collaborative (GRC) has collected an extraordinary amount of experimental torque, steady state and dynamic non-torque loads, internal loads and deflections, and condition important data and conclusions such as the importance of non-torque loads, dynamic torque events, planetary

76 FR 66057 - North American Electric Reliability Corporation; Order Approving Regional Reliability Standard

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-25

... system conditions when the system experiences dynamic events such as low frequency oscillations, or... R8 requires that dynamic disturbance recorders function continuously. To capture system disturbance... recording capability necessary to monitor the response of the Bulk-Power System to system disturbances...

Rainfall Induced Landslides in Puerto Rico (Invited)

NASA Astrophysics Data System (ADS)

Lepore, C.; Kamal, S.; Arnone, E.; Noto, V.; Shanahan, P.; Bras, R. L.

2009-12-01

Landslides are a major geologic hazard in the United States, typically triggered by rainfall, earthquakes, volcanoes and human activity. Rainfall-induced landslides are the most common type in the island of Puerto Rico, with one or two large events per year. We performed an island-wide determination of static landslide susceptibility and hazard assessment as well as dynamic modeling of rainfall-induced shallow landslides in a particular hydrologic basin. Based on statistical analysis of past landslides, we determined that reliable prediction of the susceptibility to landslides is strongly dependent on the resolution of the digital elevation model (DEM) employed and the reliability of the rainfall data. A distributed hydrology model capable of simulating landslides, tRIBS-VEGGIE, has been implemented for the first time in a humid tropical environment like Puerto Rico. The Mameyes basin, located in the Luquillo Experimental Forest in Puerto Rico, was selected for modeling based on the availability of soil, vegetation, topographical, meteorological and historic landslide data. .Application of the model yields a temporal and spatial distribution of predicted rainfall-induced landslides, which is used to predict the dynamic susceptibility of the basin to landslides.

Autonomous navigation system based on GPS and magnetometer data

NASA Technical Reports Server (NTRS)

Julie, Thienel K. (Inventor); Richard, Harman R. (Inventor); Bar-Itzhack, Itzhack Y. (Inventor)

2004-01-01

This invention is drawn to an autonomous navigation system using Global Positioning System (GPS) and magnetometers for low Earth orbit satellites. As a magnetometer is reliable and always provides information on spacecraft attitude, rate, and orbit, the magnetometer-GPS configuration solves GPS initialization problem, decreasing the convergence time for navigation estimate and improving the overall accuracy. Eventually the magnetometer-GPS configuration enables the system to avoid costly and inherently less reliable gyro for rate estimation. Being autonomous, this invention would provide for black-box spacecraft navigation, producing attitude, orbit, and rate estimates without any ground input with high accuracy and reliability.

Assessment of Change in Dynamic Psychotherapy

PubMed Central

Høglend, Per; Bøgwald, Kjell-Petter; Amlo, Svein; Heyerdahl, Oscar; Sørbye, Øystein; Marble, Alice; Sjaastad, Mary Cosgrove; Bentsen, Håvard

2000-01-01

Five scales have been developed to assess changes that are consistent with the therapeutic rationales and procedures of dynamic psychotherapy. Seven raters evaluated 50 patients before and 36 patients again after brief dynamic psychotherapy. A factor analysis indicated that the scales represent a dimension that is discriminable from general symptoms. A summary measure, Dynamic Capacity, was rated with acceptable reliability by a single rater. However, average scores of three raters were needed for good reliability of change ratings. The scales seem to be sufficiently fine-grained to capture statistically and clinically significant changes during brief dynamic psychotherapy. PMID:11069131

Nintendo Wii Balance Board is sensitive to effects of visual tasks on standing sway in healthy elderly adults.

PubMed

Koslucher, Frank; Wade, Michael G; Nelson, Brent; Lim, Kelvin; Chen, Fu-Chen; Stoffregen, Thomas A

2012-07-01

Research has shown that the Nintendo Wii Balance Board (WBB) can reliably detect the quantitative kinematics of the center of pressure in stance. Previous studies used relatively coarse manipulations (1- vs. 2-leg stance, and eyes open vs. closed). We sought to determine whether the WBB could reliably detect postural changes associated with subtle variations in visual tasks. Healthy elderly adults stood on a WBB while performing one of two visual tasks. In the Inspection task, they maintained their gaze within the boundaries of a featureless target. In the Search task, they counted the occurrence of designated target letters within a block of text. Consistent with previous studies using traditional force plates, the positional variability of the center of pressure was reduced during performance of the Search task, relative to movement during performance of the Inspection task. Using detrended fluctuation analysis, a measure of movement dynamics, we found that COP trajectories were more predictable during performance of the Search task than during performance of the Inspection task. The results indicate that the WBB is sensitive to subtle variations in both the magnitude and dynamics of body sway that are related to variations in visual tasks engaged in during stance. The WBB is an inexpensive, reliable technology that can be used to evaluate subtle characteristics of body sway in large or widely dispersed samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Shock and vibration effects on performance reliability and mechanical integrity of proton exchange membrane fuel cells: A critical review and discussion

NASA Astrophysics Data System (ADS)

Haji Hosseinloo, Ashkan; Ehteshami, Mohsen Mousavi

2017-10-01

Performance reliability and mechanical integrity are the main bottlenecks in mass commercialization of PEMFCs for applications with inherent harsh environment such as automotive and aerospace applications. Imparted shock and vibration to the fuel cell in such applications could bring about numerous issues including clamping torque loosening, gas leakage, increased electrical resistance, and structural damage and breakage. Here, we provide a comprehensive review and critique of the literature focusing on the effects of mechanically harsh environment on PEMFCs, and at the end, we suggest two main future directions in FC technology research that need immediate attention: (i) developing a generic and adequately accurate dynamic model of PEMFCs to assess the dynamic response of FC devices, and (ii) designing effective and robust shock and vibration protection systems based on the developed models in (i).

Life and reliability models for helicopter transmissions

NASA Technical Reports Server (NTRS)

Savage, M.; Knorr, R. J.; Coy, J. J.

1982-01-01

Computer models of life and reliability are presented for planetary gear trains with a fixed ring gear, input applied to the sun gear, and output taken from the planet arm. For this transmission the input and output shafts are co-axial and the input and output torques are assumed to be coaxial with these shafts. Thrust and side loading are neglected. The reliability model is based on the Weibull distributions of the individual reliabilities of the in transmission components. The system model is also a Weibull distribution. The load versus life model for the system is a power relationship as the models for the individual components. The load-life exponent and basic dynamic capacity are developed as functions of the components capacities. The models are used to compare three and four planet, 150 kW (200 hp), 5:1 reduction transmissions with 1500 rpm input speed to illustrate their use.

Investigating the Intersession Reliability of Dynamic Brain-State Properties.

PubMed

Smith, Derek M; Zhao, Yrian; Keilholz, Shella D; Schumacher, Eric H

2018-06-01

Dynamic functional connectivity metrics have much to offer to the neuroscience of individual differences of cognition. Yet, despite the recent expansion in dynamic connectivity research, limited resources have been devoted to the study of the reliability of these connectivity measures. To address this, resting-state functional magnetic resonance imaging data from 100 Human Connectome Project subjects were compared across 2 scan days. Brain states (i.e., patterns of coactivity across regions) were identified by classifying each time frame using k means clustering. This was done with and without global signal regression (GSR). Multiple gauges of reliability indicated consistency in the brain-state properties across days and GSR attenuated the reliability of the brain states. Changes in the brain-state properties across the course of the scan were investigated as well. The results demonstrate that summary metrics describing the clustering of individual time frames have adequate test/retest reliability, and thus, these patterns of brain activation may hold promise for individual-difference research.

Integrating Resource-Based and Person-Based Approaches to Understanding Wealth Effects on School Achievement

ERIC Educational Resources Information Center

Destin, Mesmin

2013-01-01

Wealth and assets have a reliable positive relationship with the achievement outcomes of students. Various approaches to understanding student achievement may inform the understanding of how wealth seems to influence children's educational experiences. This paper describes several perspectives from the student achievement literature within the…

The kinematics of upper extremity reaching: a reliability study on people with and without shoulder impingement syndrome

PubMed Central

2010-01-01

Background Tasks chosen to evaluate motor performance should reflect the movement deficits characteristic of the target population and present an appropriate challenge for the patients who would be evaluated. A reaching task that evaluates impairment characteristics of people with shoulder impingement syndrome (SIS) was developed to evaluate the motor performance of this population. The objectives of this study were to characterize the reproducibility of this reaching task in people with and without SIS and to evaluate the impact of the number of trials on reproducibility. Methods Thirty subjects with SIS and twenty healthy subjects participated in the first measurement session to evaluate intrasession reliability. Ten healthy subjects were retested within 2 to 7 days to assess intersession reliability. At each measurement session, upper extremity kinematic patterns were evaluated during a reaching task. Ten trials were recorded. Thereafter, the upper extremity position at the end of reaching and total joint excursion that occurred during reaching were calculated. Intraclass correlation coefficient (ICC) and minimal detectable change (MDC) were used to estimate intra and intersession reliability. Results Intrasession reliability for total joint excursion was good to very good when based on the first two trials (0.770.92). As for end-reach position, intrasession reliability was very good when using either the first two, first five or last five trials (ICC>0.82). Globally, MDC were smaller for the last five trials. Intersession reliability of total joint excursion and position at the end of reaching was good to very good when using the mean of the first two or five trials (0.690.82). For most joints, MDC were smaller when using all ten trials. Conclusions The reaching task proposed to evaluate the upper limb motor performance was found reliable in people with and without SIS. Furthermore, the minimal difference necessary to infer a meaningful change in motor performance was determined, indicating that relatively small changes in task performance can be interpreted as a change in motor performance. PMID:20331889

Theory of time-resolved photoelectron imaging. Comparison of a density functional with a time-dependent density functional approach

NASA Astrophysics Data System (ADS)

Suzuki, Yoshi-ichi; Seideman, Tamar; Stener, Mauro

2004-01-01

Time-resolved photoelectron differential cross sections are computed within a quantum dynamical theory that combines a formally exact solution of the nuclear dynamics with density functional theory (DFT)-based approximations of the electronic dynamics. Various observables of time-resolved photoelectron imaging techniques are computed at the Kohn-Sham and at the time-dependent DFT levels. Comparison of the results serves to assess the reliability of the former method and hence its usefulness as an economic approach for time-domain photoelectron cross section calculations, that is applicable to complex polyatomic systems. Analysis of the matrix elements that contain the electronic dynamics provides insight into a previously unexplored aspect of femtosecond-resolved photoelectron imaging.

Excited state dynamics of thiophene and bithiophene: new insights into theoretically challenging systems.

PubMed

Prlj, Antonio; Curchod, Basile F E; Corminboeuf, Clémence

2015-06-14

The computational elucidation and proper description of the ultrafast deactivation mechanisms of simple organic electronic units, such as thiophene and its oligomers, is as challenging as it is contentious. A comprehensive excited state dynamics analysis of these systems utilizing reliable electronic structure approaches is currently lacking, with earlier pictures of the photochemistry of these systems being conceived based upon high-level static computations or lower level dynamic trajectories. Here a detailed surface hopping molecular dynamics of thiophene and bithiophene using the algebraic diagrammatic construction to second order (ADC(2)) method is presented. Our findings illustrate that ring puckering plays an important role in thiophene photochemistry and that the photostability increases when going upon dimerization into bithiophene.

Performance and reliability enhancement of linear coolers

NASA Astrophysics Data System (ADS)

Mai, M.; Rühlich, I.; Schreiter, A.; Zehner, S.

2010-04-01

Highest efficiency states a crucial requirement for modern tactical IR cryocooling systems. For enhancement of overall efficiency, AIM cryocooler designs where reassessed considering all relevant loss mechanisms and associated components. Performed investigation was based on state-of-the-art simulation software featuring magnet circuitry analysis as well as computational fluid dynamics (CFD) to realistically replicate thermodynamic interactions. As a result, an improved design for AIM linear coolers could be derived. This paper gives an overview on performance enhancement activities and major results. An additional key-requirement for cryocoolers is reliability. In recent time, AIM has introduced linear coolers with full Flexure Bearing suspension on both ends of the driving mechanism incorporating Moving Magnet piston drive. In conjunction with a Pulse-Tube coldfinger these coolers are capable of meeting MTTF's (Mean Time To Failure) in excess of 50,000 hours offering superior reliability for space applications. Ongoing development also focuses on reliability enhancement, deriving space technology into tactical solutions combining both, excelling specific performance with space like reliability. Concerned publication will summarize the progress of this reliability program and give further prospect.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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 frommore » 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.« less

Gating based on internal/external signals with dynamic correlation updates.

PubMed

Wu, Huanmei; Zhao, Qingya; Berbeco, Ross I; Nishioka, Seiko; Shirato, Hiroki; Jiang, Steve B

2008-12-21

Precise localization of mobile tumor positions in real time is critical to the success of gated radiotherapy. Tumor positions are usually derived from either internal or external surrogates. Fluoroscopic gating based on internal surrogates, such as implanted fiducial markers, is accurate however requiring a large amount of imaging dose. Gating based on external surrogates, such as patient abdominal surface motion, is non-invasive however less accurate due to the uncertainty in the correlation between tumor location and external surrogates. To address these complications, we propose to investigate an approach based on hybrid gating with dynamic internal/external correlation updates. In this approach, the external signal is acquired at high frequency (such as 30 Hz) while the internal signal is sparsely acquired (such as 0.5 Hz or less). The internal signal is used to validate and update the internal/external correlation during treatment. Tumor positions are derived from the external signal based on the newly updated correlation. Two dynamic correlation updating algorithms are introduced. One is based on the motion amplitude and the other is based on the motion phase. Nine patients with synchronized internal/external motion signals are simulated retrospectively to evaluate the effectiveness of hybrid gating. The influences of different clinical conditions on hybrid gating, such as the size of gating windows, the optimal timing for internal signal acquisition and the acquisition frequency are investigated. The results demonstrate that dynamically updating the internal/external correlation in or around the gating window will reduce false positive with relatively diminished treatment efficiency. This improvement will benefit patients with mobile tumors, especially greater for early stage lung cancers, for which the tumors are less attached or freely floating in the lung.

A whole-body dual-modality radionuclide optical strategy for preclinical imaging of metastasis and heterogeneous treatment response in different microenvironments.

PubMed

Fruhwirth, Gilbert O; Diocou, Seckou; Blower, Philip J; Ng, Tony; Mullen, Greg E D

2014-04-01

Imaging spontaneous cancer cell metastasis or heterogeneous tumor responses to drug treatment in vivo is difficult to achieve. The goal was to develop a new highly sensitive and reliable preclinical longitudinal in vivo imaging model for this purpose, thereby facilitating discovery and validation of anticancer therapies or molecular imaging agents. The strategy is based on breast cancer cells stably expressing the human sodium iodide symporter (NIS) fused to a red fluorescent protein, thereby permitting radionuclide and fluorescence imaging. Using whole-body nano-SPECT/CT with (99m)TcO4(-), we followed primary tumor growth and spontaneous metastasis in the presence or absence of etoposide treatment. NIS imaging was used to classify organs as small as individual lymph nodes (LNs) to be positive or negative for metastasis, and results were confirmed by confocal fluorescence microscopy. Etoposide treatment efficacy was proven by ex vivo anticaspase 3 staining and fluorescence microscopy. In this preclinical model, we found that the NIS imaging strategy outperformed state-of-the-art (18)F-FDG imaging in its ability to detect small tumors (18.5-fold-better tumor-to-blood ratio) and metastases (LN, 3.6-fold) because of improved contrast in organs close to metastatic sites (12- and 8.5-fold-lower standardized uptake value in the heart and kidney, respectively). We applied the model to assess the treatment response to the neoadjuvant etoposide and found a consistent and reliable improvement in spontaneous metastasis detection. Importantly, we also found that tumor cells in different microenvironments responded in a heterogeneous manner to etoposide treatment, which could be determined only by the NIS-based strategy and not by (18)F-FDG imaging. We developed a new strategy for preclinical longitudinal in vivo cancer cell tracking with greater sensitivity and reliability than (18)F-FDG PET and applied it to track spontaneous and distant metastasis in the presence or absence of genotoxic stress therapy. Importantly, the model provides sufficient sensitivity and dynamic range to permit the reliable assessment of heterogeneous treatment responses in various microenvironments.

Impaired limb position sense after stroke: a quantitative test for clinical use.

PubMed

Carey, L M; Oke, L E; Matyas, T A

1996-12-01

A quantitative measure of wrist position sense was developed to advance clinical measurement of proprioceptive limb sensibility after stroke. Test-retest reliability, normative standards, and ability to discriminate impaired and unimpaired performance were investigated. Retest reliability was assessed over three sessions, and a matched-pairs study compared stroke and unimpaired subjects. Both wrists were tested, in counterbalanced order. Patients were tested in hospital-based rehabilitation units. Reliability was investigated on a consecutive sample of 35 adult stroke patients with a range of proprioceptive discrimination abilities and no evidence of neglect. A consecutive sample of 50 stroke patients and convenience sample of 50 healthy volunteers, matched for age, sex, and hand dominance, were tested in the normative-discriminative study. Age and sex were representative of the adult stroke population. The test required matching of imposed wrist positions using a pointer aligned with the axis of movement and a protractor scale. The test was reliable (r = .88 and .92) and observed changes of 8 degrees can be interpreted, with 95% confidence, as genuine. Scores of healthy volunteers ranged from 3.1 degrees to 10.9 degrees average error. The criterion of impairment was conservatively defined as 11 degrees (+/-4.8 degrees) average error. Impaired and unimpaired performance were well differentiated. Clinicians can confidently and quantitatively sample one aspect of proprioceptive sensibility in stroke patients using the wrist position sense test. Development of tests on other joints using the present approach is supported by our findings.

Reliability of shoulder internal rotation passive range of motion measurements in the supine versus sidelying position.

PubMed

Lunden, Jason B; Muffenbier, Mike; Giveans, M Russell; Cieminski, Cort J

2010-09-01

Clinical measurement, reliability. To compare intrarater and interrater reliability of shoulder internal rotation (IR) passive range of motion measurements utilizing a standard supine position and a sidelying position. Glenohumeral IR range of motion deficits are often noted in patients with shoulder pathology. Excellent intrarater reliability has been found when measuring this motion. However, interrater reliability has been reported as poor to fair. Some clinicians currently use a sidelying position for IR stretching with patients who have shoulder pathology. However, no objective data exist for IR passive range of motion measured in this sidelying position, either in terms of reliability or normative values. Seventy subjects (mean age, 36.8 years), with (n = 19) and without (n = 51) shoulder pathology, were included in this study. Shoulder IR passive range of motion of the dominant shoulder or involved shoulder was measured by 2 investigators in 2 positions: (1) a standard supine position, with the shoulder at 90 degrees of abduction, and (2) in sidelying on the tested side, with the shoulder flexed to 90 degrees . Intrarater reliability for supine measurements was good to excellent (ICC3,1 = 0.70-0.93) and for sidelying measurements was excellent (ICC3,1 = 0.94-0.98). Interrater reliability was fair to good for the supine measurement (ICC2,2 = 0.74-0.81) and good to excellent for the sidelying measurement (ICC2,2 = 0.88-0.96). The mean (range) value of the dominant shoulder sidelying IR passive range of motion was 40 degrees (11 degrees to 69 degrees ) for healthy subjects and 25 degrees (-16 degrees to 49 degrees) for subjects with shoulder pathology. For subjects with shoulder pathology, measurements of shoulder IR made in the sidelying position had superior intrarater and interrater reliability compared to those in the standard supine position.

Test-Retest Reliability of “High-Order” Functional Connectivity in Young Healthy Adults

PubMed Central

Zhang, Han; Chen, Xiaobo; Zhang, Yu; Shen, Dinggang

2017-01-01

Functional connectivity (FC) has become a leading method for resting-state functional magnetic resonance imaging (rs-fMRI) analysis. However, the majority of the previous studies utilized pairwise, temporal synchronization-based FC. Recently, high-order FC (HOFC) methods were proposed with the idea of computing “correlation of correlations” to capture high-level, more complex associations among the brain regions. There are two types of HOFC. The first type is topographical profile similarity-based HOFC (tHOFC) and its variant, associated HOFC (aHOFC), for capturing different levels of HOFC. Instead of measuring the similarity of the original rs-fMRI signals with the traditional FC (low-order FC, or LOFC), tHOFC measures the similarity of LOFC profiles (i.e., a set of LOFC values between a region and all other regions) between each pair of brain regions. The second type is dynamics-based HOFC (dHOFC) which defines the quadruple relationship among every four brain regions by first calculating two pairwise dynamic LOFC “time series” and then measuring their temporal synchronization (i.e., temporal correlation of the LOFC fluctuations, not the BOLD fluctuations). Applications have shown the superiority of HOFC in both disease biomarker detection and individualized diagnosis than LOFC. However, no study has been carried out for the assessment of test-retest reliability of different HOFC metrics. In this paper, we systematically evaluate the reliability of the two types of HOFC methods using test-retest rs-fMRI data from 25 (12 females, age 24.48 ± 2.55 years) young healthy adults with seven repeated scans (with interval = 3–8 days). We found that all HOFC metrics have satisfactory reliability, specifically (1) fair-to-good for tHOFC and aHOFC, and (2) fair-to-moderate for dHOFC with relatively strong connectivity strength. We further give an in-depth analysis of the biological meanings of each HOFC metric and highlight their differences compared to the LOFC from the aspects of cross-level information exchanges, within-/between-network connectivity, and modulatory connectivity. In addition, how the dynamic analysis parameter (i.e., sliding window length) affects dHOFC reliability is also investigated. Our study reveals unique functional associations characterized by the HOFC metrics. Guidance and recommendations for future applications and clinical research using HOFC are provided. This study has made a further step toward unveiling more complex human brain connectome. PMID:28824362

Simulation of longitudinal dynamics of long freight trains in positioning operations

NASA Astrophysics Data System (ADS)

Qi, Zhaohui; Huang, Zhihao; Kong, Xianchao

2012-09-01

Positioning operations are performed in a railway goods yard, in which the freight train is pulled precisely at a specific point by a positioner. The positioner moves strictly according to the predesigned speed and provides all the traction and braking forces which are highly dependent on the longitudinal dynamic response. In order to improve the efficiency and protect the wagons from damage during positioning operations, the design speed of the positioner has to be optimised based on the simulation of longitudinal train dynamics. However, traditional models of longitudinal train dynamics are not accurate enough in some aspects. In this study, we make some changes in the traditional theory to make it suitable for the study of long freight trains in positioning operations. In the proposed method, instead of the traction force on the train, the motion of the positioner is assumed to be known; more importantly, the traditional draft gear model with nonlinear spring and linear damping is replaced by a more detailed model based on the achievement of contact and impact mechanics; the switching effects of the resistance and the coupler slack are also taken into consideration. Numerical examples that deal with positioning operations on the straight lines, slope lines and curving lines are given.

Adaptive Robust Output Feedback Control for a Marine Dynamic Positioning System Based on a High-Gain Observer.

PubMed

Du, Jialu; Hu, Xin; Liu, Hongbo; Chen, C L Philip

2015-11-01

This paper develops an adaptive robust output feedback control scheme for dynamically positioned ships with unavailable velocities and unknown dynamic parameters in an unknown time-variant disturbance environment. The controller is designed by incorporating the high-gain observer and radial basis function (RBF) neural networks in vectorial backstepping method. The high-gain observer provides the estimations of the ship position and heading as well as velocities. The RBF neural networks are employed to compensate for the uncertainties of ship dynamics. The adaptive laws incorporating a leakage term are designed to estimate the weights of RBF neural networks and the bounds of unknown time-variant environmental disturbances. In contrast to the existing results of dynamic positioning (DP) controllers, the proposed control scheme relies only on the ship position and heading measurements and does not require a priori knowledge of the ship dynamics and external disturbances. By means of Lyapunov functions, it is theoretically proved that our output feedback controller can control a ship's position and heading to the arbitrarily small neighborhood of the desired target values while guaranteeing that all signals in the closed-loop DP control system are uniformly ultimately bounded. Finally, simulations involving two ships are carried out, and simulation results demonstrate the effectiveness of the proposed control scheme.

Computationally efficient stochastic optimization using multiple realizations

NASA Astrophysics Data System (ADS)

Bayer, P.; Bürger, C. M.; Finkel, M.

2008-02-01

The presented study is concerned with computationally efficient methods for solving stochastic optimization problems involving multiple equally probable realizations of uncertain parameters. A new and straightforward technique is introduced that is based on dynamically ordering the stack of realizations during the search procedure. The rationale is that a small number of critical realizations govern the output of a reliability-based objective function. By utilizing a problem, which is typical to designing a water supply well field, several variants of this "stack ordering" approach are tested. The results are statistically assessed, in terms of optimality and nominal reliability. This study demonstrates that the simple ordering of a given number of 500 realizations while applying an evolutionary search algorithm can save about half of the model runs without compromising the optimization procedure. More advanced variants of stack ordering can, if properly configured, save up to more than 97% of the computational effort that would be required if the entire number of realizations were considered. The findings herein are promising for similar problems of water management and reliability-based design in general, and particularly for non-convex problems that require heuristic search techniques.

Quality appraisal of generic self-reported instruments measuring health-related productivity changes: a systematic review

PubMed Central

2014-01-01

Background Health impairments can result in disability and changed work productivity imposing considerable costs for the employee, employer and society as a whole. A large number of instruments exist to measure health-related productivity changes; however their methodological quality remains unclear. This systematic review critically appraised the measurement properties in generic self-reported instruments that measure health-related productivity changes to recommend appropriate instruments for use in occupational and economic health practice. Methods PubMed, PsycINFO, Econlit and Embase were systematically searched for studies whereof: (i) instruments measured health-related productivity changes; (ii) the aim was to evaluate instrument measurement properties; (iii) instruments were generic; (iv) ratings were self-reported; (v) full-texts were available. Next, methodological quality appraisal was based on COSMIN elements: (i) internal consistency; (ii) reliability; (iii) measurement error; (iv) content validity; (v) structural validity; (vi) hypotheses testing; (vii) cross-cultural validity; (viii) criterion validity; and (ix) responsiveness. Recommendations are based on evidence syntheses. Results This review included 25 articles assessing the reliability, validity and responsiveness of 15 different generic self-reported instruments measuring health-related productivity changes. Most studies evaluated criterion validity, none evaluated cross-cultural validity and information on measurement error is lacking. The Work Limitation Questionnaire (WLQ) was most frequently evaluated with moderate respectively strong positive evidence for content and structural validity and negative evidence for reliability, hypothesis testing and responsiveness. Less frequently evaluated, the Stanford Presenteeism Scale (SPS) showed strong positive evidence for internal consistency and structural validity, and moderate positive evidence for hypotheses testing and criterion validity. The Productivity and Disease Questionnaire (PRODISQ) yielded strong positive evidence for content validity, evidence for other properties is lacking. The other instruments resulted in mostly fair-to-poor quality ratings with limited evidence. Conclusions Decisions based on the content of the instrument, usage purpose, target country and population, and available evidence are recommended. Until high-quality studies are in place to accurately assess the measurement properties of the currently available instruments, the WLQ and, in a Dutch context, the PRODISQ are cautiously preferred based on its strong positive evidence for content validity. Based on its strong positive evidence for internal consistency and structural validity, the SPS is cautiously recommended. PMID:24495301

Relationships Between Simple Toe Elevation Angle in the Standing Position and Dynamic Balance and Fall Risk Among Community-Dwelling Older Adults.

PubMed

Takatori, Katsuhiko; Matsumoto, Daisuke

2015-10-01

To investigate the relationships between toe elevation ability in the standing position and dynamic balance and fall risk among community-dwelling older adults. Cross-sectional survey. General community. Community-dwelling older adults (N = 287). Toe elevation angles in the standing position. Intra-rater and inter-rater reliability of measurements of the toe elevation angle was high (internal coefficient of correlation [ICC] (1,2) = 0.94 for the former and ICC (2,1) = 0.90 for the latter). Significant correlations were found between the toe elevation angle and age (r = -0.20, P < .01), 5-m walking time (r = -0.31, P < .01), Functional Reach Test (r = 0.36, P < .01), Timed Up and Go Test (r = -0.36, P < .01), and Chair Stand Test (r = 0.26, P < .01). Subjects who experienced a fall in the previous 6 months had a significantly lower toe elevation angle compared with subjects who did not experience a fall (t = 2.19, P < .05). Multiple regression analysis revealed that results of the Functional Reach Test (β = .22, P < .001) and Timed Up and Go Test (β = -0.74, P < .001) were significantly associated with the toe elevation angle. Toe elevation angle was an index of dynamic balance ability and appears to be a simple screening test for fall risk in community-dwelling older adults. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Trading strategy based on dynamic mode decomposition: Tested in Chinese stock market

NASA Astrophysics Data System (ADS)

Cui, Ling-xiao; Long, Wen

2016-11-01

Dynamic mode decomposition (DMD) is an effective method to capture the intrinsic dynamical modes of complex system. In this work, we adopt DMD method to discover the evolutionary patterns in stock market and apply it to Chinese A-share stock market. We design two strategies based on DMD algorithm. The strategy which considers only timing problem can make reliable profits in a choppy market with no prominent trend while fails to beat the benchmark moving-average strategy in bull market. After considering the spatial information from spatial-temporal coherent structure of DMD modes, we improved the trading strategy remarkably. Then the DMD strategies profitability is quantitatively evaluated by performing SPA test to correct the data-snooping effect. The results further prove that DMD algorithm can model the market patterns well in sideways market.

Fast Dynamic Simulation-Based Small Signal Stability Assessment and Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Acharya, Naresh; Baone, Chaitanya; Veda, Santosh

2014-12-31

Power grid planning and operation decisions are made based on simulation of the dynamic behavior of the system. Enabling substantial energy savings while increasing the reliability of the aging North American power grid through improved utilization of existing transmission assets hinges on the adoption of wide-area measurement systems (WAMS) for power system stabilization. However, adoption of WAMS alone will not suffice if the power system is to reach its full entitlement in stability and reliability. It is necessary to enhance predictability with "faster than real-time" dynamic simulations that will enable the dynamic stability margins, proactive real-time control, and improve gridmore » resiliency to fast time-scale phenomena such as cascading network failures. Present-day dynamic simulations are performed only during offline planning studies, considering only worst case conditions such as summer peak, winter peak days, etc. With widespread deployment of renewable generation, controllable loads, energy storage devices and plug-in hybrid electric vehicles expected in the near future and greater integration of cyber infrastructure (communications, computation and control), monitoring and controlling the dynamic performance of the grid in real-time would become increasingly important. The state-of-the-art dynamic simulation tools have limited computational speed and are not suitable for real-time applications, given the large set of contingency conditions to be evaluated. These tools are optimized for best performance of single-processor computers, but the simulation is still several times slower than real-time due to its computational complexity. With recent significant advances in numerical methods and computational hardware, the expectations have been rising towards more efficient and faster techniques to be implemented in power system simulators. This is a natural expectation, given that the core solution algorithms of most commercial simulators were developed decades ago, when High Performance Computing (HPC) resources were not commonly available.« less

The reliability and validity of video analysis for the assessment of the clinical signs of concussion in Australian football.

PubMed

Makdissi, Michael; Davis, Gavin

2016-10-01

The objective of this study was to determine the reliability and validity of identifying clinical signs of concussion using video analysis in Australian football. Prospective cohort study. All impacts and collisions potentially resulting in a concussion were identified during 2012 and 2013 Australian Football League seasons. Consensus definitions were developed for clinical signs associated with concussion. For intra- and inter-rater reliability analysis, two experienced clinicians independently assessed 102 randomly selected videos on two occasions. Sensitivity, specificity, positive and negative predictive values were calculated based on the diagnosis provided by team medical staff. 212 incidents resulting in possible concussion were identified in 414 Australian Football League games. The intra-rater reliability of the video-based identification of signs associated with concussion was good to excellent. Inter-rater reliability was good to excellent for impact seizure, slow to get up, motor incoordination, ragdoll appearance (2 of 4 analyses), clutching at head and facial injury. Inter-rater reliability for loss of responsiveness and blank and vacant look was only fair and did not reach statistical significance. The feature with the highest sensitivity was slow to get up (87%), but this sign had a low specificity (19%). Other video signs had a high specificity but low sensitivity. Blank and vacant look (100%) and motor incoordination (81%) had the highest positive predictive value. Video analysis may be a useful adjunct to the side-line assessment of a possible concussion. Video analysis however should not replace the need for a thorough multimodal clinical assessment. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

A method for the automated long-term monitoring of three-spined stickleback Gasterosteus aculeatus shoal dynamics.

PubMed

Kleinhappel, T K; Al-Zoubi, A; Al-Diri, B; Burman, O; Dickinson, P; John, L; Wilkinson, A; Pike, T W

2014-04-01

This paper describes and evaluates a flexible, non-invasive tagging system for the automated identification and long-term monitoring of individual three-spined sticklebacks Gasterosteus aculeatus. The system is based on barcoded tags, which can be reliably and robustly detected and decoded to provide information on an individual's identity and location. Because large numbers of fish can be individually tagged, it can be used to monitor individual- and group-level dynamics within fish shoals. © 2014 The Fisheries Society of the British Isles.

Robustness and Reliability of Synergy-Based Myocontrol of a Multiple Degree of Freedom Robotic Arm.

PubMed

Lunardini, Francesca; Casellato, Claudia; d'Avella, Andrea; Sanger, Terence D; Pedrocchi, Alessandra

2016-09-01

In this study, we test the feasibility of the synergy- based approach for application in the realistic and clinically oriented framework of multi-degree of freedom (DOF) robotic control. We developed and tested online ten able-bodied subjects in a semi-supervised method to achieve simultaneous, continuous control of two DOFs of a robotic arm, using muscle synergies extracted from upper limb muscles while performing flexion-extension movements of the elbow and shoulder joints in the horizontal plane. To validate the efficacy of the synergy-based approach in extracting reliable control signals, compared to the simple muscle-pair method typically used in commercial applications, we evaluated the repeatability of the algorithm over days, the effect of the arm dynamics on the control performance, and the robustness of the control scheme to the presence of co-contraction between pairs of antagonist muscles. Results showed that, without the need for a daily calibration, all subjects were able to intuitively and easily control the synergy-based myoelectric interface in different scenarios, using both dynamic and isometric muscle contractions. The proposed control scheme was shown to be robust to co-contraction between antagonist muscles, providing better performance compared to the traditional muscle-pair approach. The current study is a first step toward user-friendly application of synergy-based myocontrol of assistive robotic devices.

Effects of back posture education on elementary schoolchildren's back function.

PubMed

Geldhof, Elisabeth; Cardon, Greet; De Bourdeaudhuij, Ilse; Danneels, Lieven; Coorevits, Pascal; Vanderstraeten, Guy; De Clercq, Dirk

2007-06-01

The possible effects of back education on children's back function were never evaluated. Therefore, main aim of the present study was to evaluate the effects of back education in elementary schoolchildren on back function parameters. Since the reliability of back function measurement in children is poorly defined, another objective was to test the selected instruments for reliability in 8-11-year olds. The multi-factorial intervention lasting two school-years consisted of a back education program and the stimulation of postural dynamism in the class. Trunk muscle endurance, leg muscle capacity and spinal curvature were evaluated in a pre-post design including 41 children who received the back education program (mean age at post-test: 11.2 +/- 0.9 years) and 28 controls (mean age at post-test: 11.4 +/- 0.6 years). Besides, test-retest reliability with a 1-week interval was investigated in a separate sample. Therefore, 47 children (mean age: 10.1 +/- 0.5 years) were tested for reliability of trunk muscle endurance and 40 children (mean age: 10.2 +/- 0.7 years) for the assessment of spinal curvatures. Reliability of endurance testing was very good to good for the trunk flexors (ICC = 0.82) and trunk extensors (ICC = 0.63). The assessment of the thoracic (ICC = 0.69) and the lumbar curvature (ICC = 0.52) in seating position showed good to acceptable reliability. Low ICCs were found for the assessment of the thoracic (ICC = 0.39) and the lumbar curvature (ICC = 0.37) in stance. The effects of 2 year back education showed an increase in trunk flexor endurance in the intervention group compared to a decrease in the controls and a trend towards significance for a higher increase in trunk extensor endurance in the intervention group. For leg muscle capacity and spinal curvature no intervention effects were found. The small samples recommend cautious interpretation of intervention effects. However, the present study's findings favor the implementation of back education with focus on postural dynamism in the class as an integral part of the elementary school curriculum in the scope of optimizing spinal loading through the school environment.

Generation of Pax6-IRES-EGFP knock-in mouse via the cloning-free CRISPR/Cas9 system to reliably visualize neurodevelopmental dynamics.

PubMed

Inoue, Yukiko U; Morimoto, Yuki; Hoshino, Mikio; Inoue, Takayoshi

2018-07-01

Pax6 encodes a transcription factor that plays pivotal roles in eye development, early brain patterning, neocortical arealization, and so forth. Visualization of Pax6 expression dynamics in these events could offer numerous advantages to neurodevelopmental studies. While CRISPR/Cas9 system has dramatically accelerated one-step generation of knock-out mouse, establishment of gene-cassette knock-in mouse via zygote injection has been considered insufficient due to its low efficiency. Recently, an improved CRISPR/Cas9 system for effective gene-cassette knock-in has been reported, where the native form of guide RNAs (crRNA and tracrRNA) assembled with recombinant Cas9 protein are directly delivered into mouse fertilized eggs. Here we apply this strategy to insert IRES-EGFP-pA cassette into Pax6 locus and achieve efficient targeted insertions of the 1.8 kb reporter gene. In Pax6-IRES-EGFP mouse we have generated, EGFP-positive cells reside in the eyes and cerebellum as endogenous Pax6 expressing cells at postnatal day 2. At the early embryonic stages when the embryos are transparent, EGFP-positive regions can be easily identified without PCR-based genotyping, precisely recapitulating the endogenous Pax6 expression patterns. Remarkably, at E12.5, the graded expression patterns of Pax6 in the developing neocortex now become recognizable in our knock-in mice, serving a sufficiently sensitive and useful tool to precisely visualize neurodevelopmental processes. Copyright © 2018 Elsevier B.V. and Japan Neuroscience Society. All rights reserved.

Review of Dynamic Modeling and Simulation of Large Scale Belt Conveyor System

NASA Astrophysics Data System (ADS)

He, Qing; Li, Hong

Belt conveyor is one of the most important devices to transport bulk-solid material for long distance. Dynamic analysis is the key to decide whether the design is rational in technique, safe and reliable in running, feasible in economy. It is very important to study dynamic properties, improve efficiency and productivity, guarantee conveyor safe, reliable and stable running. The dynamic researches and applications of large scale belt conveyor are discussed. The main research topics, the state-of-the-art of dynamic researches on belt conveyor are analyzed. The main future works focus on dynamic analysis, modeling and simulation of main components and whole system, nonlinear modeling, simulation and vibration analysis of large scale conveyor system.

3-D scapular kinematics during arm elevation: effect of motion velocity.

PubMed

Fayad, F; Hoffmann, G; Hanneton, S; Yazbeck, C; Lefevre-Colau, M M; Poiraudeau, S; Revel, M; Roby-Brami, A

2006-11-01

No three-dimensional (3-D) data exist on the influence of motion velocity on scapular kinematics. The effect of arm elevation velocity has been studied only in a two-dimensional setting. Thirty healthy subjects performed dominant (right) arm elevation in two planes, sagittal and frontal, and at slow and fast self-selected arm speed. Scapular orientation and humeral elevation were measured at 30 Hz recording frequency with use of a 6-degree-of-freedom electromagnetic system (Polhemus Fastraka). Motion was computed according to the International Society of Biomechanics standards. Scapular orientation was also determined with the arm held in different static positions. We obtained a full 3-D kinematic description of scapula achieving a reliable, complex 3-D motion during humeral elevation and lowering. The maximal sagittal arm elevation showed a characteristic "M"-shape pattern of protraction/retraction curve. Scapular rotations did not differ significantly between slow and fast movements. Moreover, protraction/retraction and tilt angular values did not differ significantly between static and dynamic tasks. However, scapular lateral rotation values differed between static and dynamic measurements during sagittal and frontal arm elevation. Lateral scapular rotation appears to be less in static than in dynamic measurement, particularly in the sagittal plane. Interpolation of statically recorded positions of the bones cannot reflect the kinematics of the scapula.

Entry Grades and Academic Performance in Nigerian Universities.

ERIC Educational Resources Information Center

Ojo, Folayan

1976-01-01

The reliability of Nigeria's entry qualification examinations as a predictor of success at the university level is examined. Results indicate a positive correlation in the science-based fields and very low predictability in the social sciences. (JMF)

Reliability and concurrent validity of the Microsoft Xbox One Kinect for assessment of standing balance and postural control.

PubMed

Clark, Ross A; Pua, Yong-Hao; Oliveira, Cristino C; Bower, Kelly J; Thilarajah, Shamala; McGaw, Rebekah; Hasanki, Ksaniel; Mentiplay, Benjamin F

2015-07-01

The Microsoft Kinect V2 for Windows, also known as the Xbox One Kinect, includes new and potentially far improved depth and image sensors which may increase its accuracy for assessing postural control and balance. The aim of this study was to assess the concurrent validity and reliability of kinematic data recorded using a marker-based three dimensional motion analysis (3DMA) system and the Kinect V2 during a variety of static and dynamic balance assessments. Thirty healthy adults performed two sessions, separated by one week, consisting of static standing balance tests under different visual (eyes open vs. closed) and supportive (single limb vs. double limb) conditions, and dynamic balance tests consisting of forward and lateral reach and an assessment of limits of stability. Marker coordinate and joint angle data were concurrently recorded using the Kinect V2 skeletal tracking algorithm and the 3DMA system. Task-specific outcome measures from each system on Day 1 and 2 were compared. Concurrent validity of trunk angle data during the dynamic tasks and anterior-posterior range and path length in the static balance tasks was excellent (Pearson's r>0.75). In contrast, concurrent validity for medial-lateral range and path length was poor to modest for all trials except single leg eyes closed balance. Within device test-retest reliability was variable; however, the results were generally comparable between devices. In conclusion, the Kinect V2 has the potential to be used as a reliable and valid tool for the assessment of some aspects of balance performance. Copyright © 2015 Elsevier B.V. All rights reserved.

Development, scoring, and reliability of the Microscale Audit of Pedestrian Streetscapes (MAPS)

PubMed Central

2013-01-01

Background Streetscape (microscale) features of the built environment can influence people’s perceptions of their neighborhoods’ suitability for physical activity. Many microscale audit tools have been developed, but few have published systematic scoring methods. We present the development, scoring, and reliability of the Microscale Audit of Pedestrian Streetscapes (MAPS) tool and its theoretically-based subscales. Methods MAPS was based on prior instruments and was developed to assess details of streetscapes considered relevant for physical activity. MAPS sections (route, segments, crossings, and cul-de-sacs) were scored by two independent raters for reliability analyses. There were 290 route pairs, 516 segment pairs, 319 crossing pairs, and 53 cul-de-sac pairs in the reliability sample. Individual inter-rater item reliability analyses were computed using Kappa, intra-class correlation coefficient (ICC), and percent agreement. A conceptual framework for subscale creation was developed using theory, expert consensus, and policy relevance. Items were grouped into subscales, and subscales were analyzed for inter-rater reliability at tiered levels of aggregation. Results There were 160 items included in the subscales (out of 201 items total). Of those included in the subscales, 80 items (50.0%) had good/excellent reliability, 41 items (25.6%) had moderate reliability, and 18 items (11.3%) had low reliability, with limited variability in the remaining 21 items (13.1%). Seventeen of the 20 route section subscales, valence (positive/negative) scores, and overall scores (85.0%) demonstrated good/excellent reliability and 3 demonstrated moderate reliability. Of the 16 segment subscales, valence scores, and overall scores, 12 (75.0%) demonstrated good/excellent reliability, three demonstrated moderate reliability, and one demonstrated poor reliability. Of the 8 crossing subscales, valence scores, and overall scores, 6 (75.0%) demonstrated good/excellent reliability, and 2 demonstrated moderate reliability. The cul-de-sac subscale demonstrated good/excellent reliability. Conclusions MAPS items and subscales predominantly demonstrated moderate to excellent reliability. The subscales and scoring system represent a theoretically based framework for using these complex microscale data and may be applicable to other similar instruments. PMID:23621947

Forecasting infectious disease emergence subject to seasonal forcing.

PubMed

Miller, Paige B; O'Dea, Eamon B; Rohani, Pejman; Drake, John M

2017-09-06

Despite high vaccination coverage, many childhood infections pose a growing threat to human populations. Accurate disease forecasting would be of tremendous value to public health. Forecasting disease emergence using early warning signals (EWS) is possible in non-seasonal models of infectious diseases. Here, we assessed whether EWS also anticipate disease emergence in seasonal models. We simulated the dynamics of an immunizing infectious pathogen approaching the tipping point to disease endemicity. To explore the effect of seasonality on the reliability of early warning statistics, we varied the amplitude of fluctuations around the average transmission. We proposed and analyzed two new early warning signals based on the wavelet spectrum. We measured the reliability of the early warning signals depending on the strength of their trend preceding the tipping point and then calculated the Area Under the Curve (AUC) statistic. Early warning signals were reliable when disease transmission was subject to seasonal forcing. Wavelet-based early warning signals were as reliable as other conventional early warning signals. We found that removing seasonal trends, prior to analysis, did not improve early warning statistics uniformly. Early warning signals anticipate the onset of critical transitions for infectious diseases which are subject to seasonal forcing. Wavelet-based early warning statistics can also be used to forecast infectious disease.

Manual unloading of the lumbar spine: can it identify immediate responders to mechanical traction in a low back pain population? A study of reliability and criterion referenced predictive validity

PubMed Central

Swanson, Brian T.; Riley, Sean P.; Cote, Mark P.; Leger, Robin R.; Moss, Isaac L.; Carlos,, John

2016-01-01

Background To date, no research has examined the reliability or predictive validity of manual unloading tests of the lumbar spine to identify potential responders to lumbar mechanical traction. Purpose To determine: (1) the intra and inter-rater reliability of a manual unloading test of the lumbar spine and (2) the criterion referenced predictive validity for the manual unloading test. Methods Ten volunteers with low back pain (LBP) underwent a manual unloading test to establish reliability. In a separate procedure, 30 consecutive patients with LBP (age 50·86±11·51) were assessed for pain in their most provocative standing position (visual analog scale (VAS) 49·53±25·52 mm). Patients were assessed with a manual unloading test in their most provocative position followed by a single application of intermittent mechanical traction. Post traction, pain in the provocative position was reassessed and utilized as the outcome criterion. Results The test of unloading demonstrated substantial intra and inter-rater reliability K = 1·00, P = 0·002, K = 0·737, P = 0·001, respectively. There were statistically significant within group differences for pain response following traction for patients with a positive manual unloading test (P<0·001), while patients with a negative manual unloading test did not demonstrate a statistically significant change (P>0·05). There were significant between group differences for proportion of responders to traction based on manual unloading response (P = 0·031), and manual unloading response demonstrated a moderate to strong relationship with traction response Phi = 0·443, P = 0·015. Discussion and conclusion The manual unloading test appears to be a reliable test and has a moderate to strong correlation with pain relief that exceeds minimal clinically important difference (MCID) following traction supporting the validity of this test. PMID:27559274

Representing Causation

ERIC Educational Resources Information Center

Wolff, Phillip

2007-01-01

The dynamics model, which is based on L. Talmy's (1988) theory of force dynamics, characterizes causation as a pattern of forces and a position vector. In contrast to counterfactual and probabilistic models, the dynamics model naturally distinguishes between different cause-related concepts and explains the induction of causal relationships from…

[Reliability theory based on quality risk network analysis for Chinese medicine injection].

PubMed

Li, Zheng; Kang, Li-Yuan; Fan, Xiao-Hui

2014-08-01

A new risk analysis method based upon reliability theory was introduced in this paper for the quality risk management of Chinese medicine injection manufacturing plants. The risk events including both cause and effect ones were derived in the framework as nodes with a Bayesian network analysis approach. It thus transforms the risk analysis results from failure mode and effect analysis (FMEA) into a Bayesian network platform. With its structure and parameters determined, the network can be used to evaluate the system reliability quantitatively with probabilistic analytical appraoches. Using network analysis tools such as GeNie and AgenaRisk, we are able to find the nodes that are most critical to influence the system reliability. The importance of each node to the system can be quantitatively evaluated by calculating the effect of the node on the overall risk, and minimization plan can be determined accordingly to reduce their influences and improve the system reliability. Using the Shengmai injection manufacturing plant of SZYY Ltd as a user case, we analyzed the quality risk with both static FMEA analysis and dynamic Bayesian Network analysis. The potential risk factors for the quality of Shengmai injection manufacturing were identified with the network analysis platform. Quality assurance actions were further defined to reduce the risk and improve the product quality.

Global fast dynamic terminal sliding mode control for a quadrotor UAV.

PubMed

Xiong, Jing-Jing; Zhang, Guo-Bao

2017-01-01

A control method based on global fast dynamic terminal sliding mode control (TSMC) technique is proposed to design the flight controller for performing the finite-time position and attitude tracking control of a small quadrotor UAV. Firstly, the dynamic model of the quadrotor is divided into two subsystems, i.e., a fully actuated subsystem and an underactuated subsystem. Secondly, the dynamic flight controllers of the quadrotor are formulated based on global fast dynamic TSMC, which is able to guarantee that the position and velocity tracking errors of all system state variables converge to zero in finite-time. Moreover, the global fast dynamic TSMC is also able to eliminate the chattering phenomenon caused by the switching control action and realize the high precision performance. In addition, the stabilities of two subsystems are demonstrated by Lyapunov theory, respectively. Lastly, the simulation results are given to illustrate the effectiveness and robustness of the proposed control method in the presence of external disturbances. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Analysis of the Multi Strategy Goal Programming for Micro-Grid Based on Dynamic ant Genetic Algorithm

NASA Astrophysics Data System (ADS)

Qiu, J. P.; Niu, D. X.

Micro-grid is one of the key technologies of the future energy supplies. Take economic planning. reliability, and environmental protection of micro grid as a basis for the analysis of multi-strategy objective programming problems for micro grid which contains wind power, solar power, and battery and micro gas turbine. Establish the mathematical model of each power generation characteristics and energy dissipation. and change micro grid planning multi-objective function under different operating strategies to a single objective model based on AHP method. Example analysis shows that in combination with dynamic ant mixed genetic algorithm can get the optimal power output of this model.

Reliable binary cell-fate decisions based on oscillations

NASA Astrophysics Data System (ADS)

Pfeuty, B.; Kaneko, K.

2014-02-01

Biological systems have often to perform binary decisions under highly dynamic and noisy environments, such as during cell-fate determination. These decisions can be implemented by two main bifurcation mechanisms based on the transitions from either monostability or oscillation to bistability. We compare these two mechanisms by using stochastic models with time-varying fields and by establishing asymptotic formulas for the choice probabilities. Different scaling laws for decision sensitivity with respect to noise strength and signal timescale are obtained, supporting a role for oscillatory dynamics in performing noise-robust and temporally tunable binary decision-making. This result provides a rationale for recent experimental evidences showing that oscillatory expression of proteins often precedes binary cell-fate decisions.

Reliability Generalization: An Examination of the Positive Affect and Negative Affect Schedule

ERIC Educational Resources Information Center

Leue, Anja; Lange, Sebastian

2011-01-01

The assessment of positive affect (PA) and negative affect (NA) by means of the Positive Affect and Negative Affect Schedule has received a remarkable popularity in the social sciences. Using a meta-analytic tool--namely, reliability generalization (RG)--population reliability scores of both scales have been investigated on the basis of a random…

Measurement error: Implications for diagnosis and discrepancy models of developmental dyslexia.

PubMed

Cotton, Sue M; Crewther, David P; Crewther, Sheila G

2005-08-01

The diagnosis of developmental dyslexia (DD) is reliant on a discrepancy between intellectual functioning and reading achievement. Discrepancy-based formulae have frequently been employed to establish the significance of the difference between 'intelligence' and 'actual' reading achievement. These formulae, however, often fail to take into consideration test reliability and the error associated with a single test score. This paper provides an illustration of the potential effects that test reliability and measurement error can have on the diagnosis of dyslexia, with particular reference to discrepancy models. The roles of reliability and standard error of measurement (SEM) in classic test theory are also briefly reviewed. This is followed by illustrations of how SEM and test reliability can aid with the interpretation of a simple discrepancy-based formula of DD. It is proposed that a lack of consideration of test theory in the use of discrepancy-based models of DD can lead to misdiagnosis (both false positives and false negatives). Further, misdiagnosis in research samples affects reproducibility and generalizability of findings. This in turn, may explain current inconsistencies in research on the perceptual, sensory, and motor correlates of dyslexia.

Spatially explicit dynamic N-mixture models

USGS Publications Warehouse

Zhao, Qing; Royle, Andy; Boomer, G. Scott

2017-01-01

Knowledge of demographic parameters such as survival, reproduction, emigration, and immigration is essential to understand metapopulation dynamics. Traditionally the estimation of these demographic parameters requires intensive data from marked animals. The development of dynamic N-mixture models makes it possible to estimate demographic parameters from count data of unmarked animals, but the original dynamic N-mixture model does not distinguish emigration and immigration from survival and reproduction, limiting its ability to explain important metapopulation processes such as movement among local populations. In this study we developed a spatially explicit dynamic N-mixture model that estimates survival, reproduction, emigration, local population size, and detection probability from count data under the assumption that movement only occurs among adjacent habitat patches. Simulation studies showed that the inference of our model depends on detection probability, local population size, and the implementation of robust sampling design. Our model provides reliable estimates of survival, reproduction, and emigration when detection probability is high, regardless of local population size or the type of sampling design. When detection probability is low, however, our model only provides reliable estimates of survival, reproduction, and emigration when local population size is moderate to high and robust sampling design is used. A sensitivity analysis showed that our model is robust against the violation of the assumption that movement only occurs among adjacent habitat patches, suggesting wide applications of this model. Our model can be used to improve our understanding of metapopulation dynamics based on count data that are relatively easy to collect in many systems.

Topological characterization and early detection of bifurcations and chaos in complex systems using persistent homology.

PubMed

Mittal, Khushboo; Gupta, Shalabh

2017-05-01

Early detection of bifurcations and chaos and understanding their topological characteristics are essential for safe and reliable operation of various electrical, chemical, physical, and industrial processes. However, the presence of non-linearity and high-dimensionality in system behavior makes this analysis a challenging task. The existing methods for dynamical system analysis provide useful tools for anomaly detection (e.g., Bendixson-Dulac and Poincare-Bendixson criteria can detect the presence of limit cycles); however, they do not provide a detailed topological understanding about system evolution during bifurcations and chaos, such as the changes in the number of subcycles and their positions, lifetimes, and sizes. This paper addresses this research gap by using topological data analysis as a tool to study system evolution and develop a mathematical framework for detecting the topological changes in the underlying system using persistent homology. Using the proposed technique, topological features (e.g., number of relevant k-dimensional holes, etc.) are extracted from nonlinear time series data which are useful for deeper analysis of the system behavior and early detection of bifurcations and chaos. When applied to a Logistic map, a Duffing oscillator, and a real life Op-amp based Jerk circuit, these features are shown to accurately characterize the system dynamics and detect the onset of chaos.

Ab Initio Potential Energy Surfaces and Quantum Dynamics for Polyatomic Bimolecular Reactions.

PubMed

Fu, Bina; Zhang, Dong H

2018-05-08

There has been great progress in the development of potential energy surfaces (PESs) and quantum dynamics calculations in the gas phase. The establishment of a fitting procedure for highly accurate PESs and new developments in quantum reactive scattering on reliable PESs allow accurate characterization of reaction dynamics beyond triatomic systems. This review will give the recent development in our group in constructing ab initio PESs based on neural networks and the time-dependent wave packet calculations for bimolecular reactions beyond three atoms. Bimolecular reactions of current interest to the community, namely, OH + H 2 , H + H 2 O, OH + CO, H + CH 4 , and Cl + CH 4 , are focused on. Quantum mechanical characterization of these reactions uncovers interesting dynamical phenomena with an unprecedented level of sophistication and has greatly advanced our understanding of polyatomic reaction dynamics.

Flows of Wet Foamsand Concentrated Emulsions

NASA Technical Reports Server (NTRS)

Nemer, Martin B.

2005-01-01

The aim of this project was is to advance a microstructural understanding of foam and emulsion flows. The dynamics of individual surfactant-covered drops and well as the collective behavior of dilute and concentrated was explored using numerical simulations. The long-range goal of this work is the formulation of reliable microphysically-based statistical models of emulsion flows.

Time zero determination for FEL pump-probe studies based on ultrafast melting of bismuth.

PubMed

Epp, S W; Hada, M; Zhong, Y; Kumagai, Y; Motomura, K; Mizote, S; Ono, T; Owada, S; Axford, D; Bakhtiarzadeh, S; Fukuzawa, H; Hayashi, Y; Katayama, T; Marx, A; Müller-Werkmeister, H M; Owen, R L; Sherrell, D A; Tono, K; Ueda, K; Westermeier, F; Miller, R J D

2017-09-01

A common challenge for pump-probe studies of structural dynamics at X-ray free-electron lasers (XFELs) is the determination of time zero (T 0 )-the time an optical pulse (e.g., an optical laser) arrives coincidently with the probe pulse (e.g., a XFEL pulse) at the sample position. In some cases, T 0 might be extracted from the structural dynamics of the sample's observed response itself, but generally, an independent robust method is required or would be superior to the inferred determination of T 0 . In this paper, we present how the structural dynamics in ultrafast melting of bismuth can be exploited for a quickly performed, reliable and accurate determination of T 0 with a precision below 20 fs and an overall experimental accuracy of 50 fs to 150 fs (estimated). Our approach is potentially useful and applicable for fixed-target XFEL experiments, such as serial femtosecond crystallography, utilizing an optical pump pulse in the ultraviolet to near infrared spectral range and a pixelated 2D photon detector for recording crystallographic diffraction patterns in transmission geometry. In comparison to many other suitable approaches, our method is fairly independent of the pumping wavelength (UV-IR) as well as of the X-ray energy and offers a favorable signal contrast. The technique is exploitable not only for the determination of temporal characteristics of the experiment at the interaction point but also for investigating important conditions affecting experimental control such as spatial overlap and beam spot sizes.

A multifactor approach to forecasting Romanian gross domestic product (GDP) in the short run.

PubMed

Armeanu, Daniel; Andrei, Jean Vasile; Lache, Leonard; Panait, Mirela

2017-01-01

The purpose of this paper is to investigate the application of a generalized dynamic factor model (GDFM) based on dynamic principal components analysis to forecasting short-term economic growth in Romania. We have used a generalized principal components approach to estimate a dynamic model based on a dataset comprising 86 economic and non-economic variables that are linked to economic output. The model exploits the dynamic correlations between these variables and uses three common components that account for roughly 72% of the information contained in the original space. We show that it is possible to generate reliable forecasts of quarterly real gross domestic product (GDP) using just the common components while also assessing the contribution of the individual variables to the dynamics of real GDP. In order to assess the relative performance of the GDFM to standard models based on principal components analysis, we have also estimated two Stock-Watson (SW) models that were used to perform the same out-of-sample forecasts as the GDFM. The results indicate significantly better performance of the GDFM compared with the competing SW models, which empirically confirms our expectations that the GDFM produces more accurate forecasts when dealing with large datasets.

Control Parameters Optimization Based on Co-Simulation of a Mechatronic System for an UA-Based Two-Axis Inertially Stabilized Platform.

PubMed

Zhou, Xiangyang; Zhao, Beilei; Gong, Guohao

2015-08-14

This paper presents a method based on co-simulation of a mechatronic system to optimize the control parameters of a two-axis inertially stabilized platform system (ISP) applied in an unmanned airship (UA), by which high control performance and reliability of the ISP system are achieved. First, a three-dimensional structural model of the ISP is built by using the three-dimensional parametric CAD software SOLIDWORKS(®); then, to analyze the system's kinematic and dynamic characteristics under operating conditions, dynamics modeling is conducted by using the multi-body dynamics software ADAMS™, thus the main dynamic parameters such as displacement, velocity, acceleration and reaction curve are obtained, respectively, through simulation analysis. Then, those dynamic parameters were input into the established MATLAB(®) SIMULINK(®) controller to simulate and test the performance of the control system. By these means, the ISP control parameters are optimized. To verify the methods, experiments were carried out by applying the optimized parameters to the control system of a two-axis ISP. The results show that the co-simulation by using virtual prototyping (VP) is effective to obtain optimized ISP control parameters, eventually leading to high ISP control performance.

Control Parameters Optimization Based on Co-Simulation of a Mechatronic System for an UA-Based Two-Axis Inertially Stabilized Platform

PubMed Central

Zhou, Xiangyang; Zhao, Beilei; Gong, Guohao

2015-01-01

This paper presents a method based on co-simulation of a mechatronic system to optimize the control parameters of a two-axis inertially stabilized platform system (ISP) applied in an unmanned airship (UA), by which high control performance and reliability of the ISP system are achieved. First, a three-dimensional structural model of the ISP is built by using the three-dimensional parametric CAD software SOLIDWORKS®; then, to analyze the system’s kinematic and dynamic characteristics under operating conditions, dynamics modeling is conducted by using the multi-body dynamics software ADAMS™, thus the main dynamic parameters such as displacement, velocity, acceleration and reaction curve are obtained, respectively, through simulation analysis. Then, those dynamic parameters were input into the established MATLAB® SIMULINK® controller to simulate and test the performance of the control system. By these means, the ISP control parameters are optimized. To verify the methods, experiments were carried out by applying the optimized parameters to the control system of a two-axis ISP. The results show that the co-simulation by using virtual prototyping (VP) is effective to obtain optimized ISP control parameters, eventually leading to high ISP control performance. PMID:26287210

A multifactor approach to forecasting Romanian gross domestic product (GDP) in the short run

PubMed Central

Armeanu, Daniel; Lache, Leonard; Panait, Mirela

2017-01-01

The purpose of this paper is to investigate the application of a generalized dynamic factor model (GDFM) based on dynamic principal components analysis to forecasting short-term economic growth in Romania. We have used a generalized principal components approach to estimate a dynamic model based on a dataset comprising 86 economic and non-economic variables that are linked to economic output. The model exploits the dynamic correlations between these variables and uses three common components that account for roughly 72% of the information contained in the original space. We show that it is possible to generate reliable forecasts of quarterly real gross domestic product (GDP) using just the common components while also assessing the contribution of the individual variables to the dynamics of real GDP. In order to assess the relative performance of the GDFM to standard models based on principal components analysis, we have also estimated two Stock-Watson (SW) models that were used to perform the same out-of-sample forecasts as the GDFM. The results indicate significantly better performance of the GDFM compared with the competing SW models, which empirically confirms our expectations that the GDFM produces more accurate forecasts when dealing with large datasets. PMID:28742100

Real-Time GNSS-Based Attitude Determination in the Measurement Domain.

PubMed

Zhao, Lin; Li, Na; Li, Liang; Zhang, Yi; Cheng, Chun

2017-02-05

A multi-antenna-based GNSS receiver is capable of providing high-precision and drift-free attitude solution. Carrier phase measurements need be utilized to achieve high-precision attitude. The traditional attitude determination methods in the measurement domain and the position domain resolve the attitude and the ambiguity sequentially. The redundant measurements from multiple baselines have not been fully utilized to enhance the reliability of attitude determination. A multi-baseline-based attitude determination method in the measurement domain is proposed to estimate the attitude parameters and the ambiguity simultaneously. Meanwhile, the redundancy of attitude resolution has also been increased so that the reliability of ambiguity resolution and attitude determination can be enhanced. Moreover, in order to further improve the reliability of attitude determination, we propose a partial ambiguity resolution method based on the proposed attitude determination model. The static and kinematic experiments were conducted to verify the performance of the proposed method. When compared with the traditional attitude determination methods, the static experimental results show that the proposed method can improve the accuracy by at least 0.03° and enhance the continuity by 18%, at most. The kinematic result has shown that the proposed method can obtain an optimal balance between accuracy and reliability performance.

A Simple Negative Interaction in the Positive Transcriptional Feedback of a Single Gene Is Sufficient to Produce Reliable Oscillations

PubMed Central

Miró-Bueno, Jesús M.; Rodríguez-Patón, Alfonso

2011-01-01

Negative and positive transcriptional feedback loops are present in natural and synthetic genetic oscillators. A single gene with negative transcriptional feedback needs a time delay and sufficiently strong nonlinearity in the transmission of the feedback signal in order to produce biochemical rhythms. A single gene with only positive transcriptional feedback does not produce oscillations. Here, we demonstrate that this single-gene network in conjunction with a simple negative interaction can also easily produce rhythms. We examine a model comprised of two well-differentiated parts. The first is a positive feedback created by a protein that binds to the promoter of its own gene and activates the transcription. The second is a negative interaction in which a repressor molecule prevents this protein from binding to its promoter. A stochastic study shows that the system is robust to noise. A deterministic study identifies that the dynamics of the oscillator are mainly driven by two types of biomolecules: the protein, and the complex formed by the repressor and this protein. The main conclusion of this paper is that a simple and usual negative interaction, such as degradation, sequestration or inhibition, acting on the positive transcriptional feedback of a single gene is a sufficient condition to produce reliable oscillations. One gene is enough and the positive transcriptional feedback signal does not need to activate a second repressor gene. This means that at the genetic level an explicit negative feedback loop is not necessary. The model needs neither cooperative binding reactions nor the formation of protein multimers. Therefore, our findings could help to clarify the design principles of cellular clocks and constitute a new efficient tool for engineering synthetic genetic oscillators. PMID:22205920

Three-dimensional scapular kinematics during the throwing motion.

PubMed

Meyer, Kristin E; Saether, Erin E; Soiney, Emily K; Shebeck, Meegan S; Paddock, Keith L; Ludewig, Paula M

2008-02-01

Proper scapular motion is crucial for normal shoulder mechanics. Scapular motion affects glenohumeral joint function during throwing, yet little is known about this dynamic activity. Asymptomatic subjects (10 male and 10 female), ages 21 to 45, were analyzed. Electromagnetic surface sensors on the sternum, acromion, and humerus were used to collect 3-D motion data during three trials of low-velocity throwing. Scapular angular position data were described or five predetermined events throughout the throw corresponding with classic descriptions of throwing phases, and trial-to-trial reliability was determined. ANOVA compared scapular angles across events. Subjects demonstrated good to excellent reliability between trials of the throw (ICC 0.74-0.98). The scapula demonstrated a pattern of external rotation, upward rotation (peak of approx. 40 degrees), and poster humeral horizontal abduction. During the arm acceleration phase, the scapula moved toward greater internal rotation and began anteriorly tilting. At maximum humeral internal rotation, the scapula ended in internal rotation (55 degrees), upward rotation (20 degrees), and anterior tilting (3 degrees). Significant differences in scapular position (p<0.05) were identified across the throwing motion. Scapular data identify events in the throwing motion in which throwers may be more susceptible to shoulder pathologies related to abnormal scapular kinematics.

User's guide to the Fault Inferring Nonlinear Detection System (FINDS) computer program

NASA Technical Reports Server (NTRS)

Caglayan, A. K.; Godiwala, P. M.; Satz, H. S.

1988-01-01

Described are the operation and internal structure of the computer program FINDS (Fault Inferring Nonlinear Detection System). The FINDS algorithm is designed to provide reliable estimates for aircraft position, velocity, attitude, and horizontal winds to be used for guidance and control laws in the presence of possible failures in the avionics sensors. The FINDS algorithm was developed with the use of a digital simulation of a commercial transport aircraft and tested with flight recorded data. The algorithm was then modified to meet the size constraints and real-time execution requirements on a flight computer. For the real-time operation, a multi-rate implementation of the FINDS algorithm has been partitioned to execute on a dual parallel processor configuration: one based on the translational dynamics and the other on the rotational kinematics. The report presents an overview of the FINDS algorithm, the implemented equations, the flow charts for the key subprograms, the input and output files, program variable indexing convention, subprogram descriptions, and the common block descriptions used in the program.

Analysis of Video-Based Microscopic Particle Trajectories Using Kalman Filtering

PubMed Central

Wu, Pei-Hsun; Agarwal, Ashutosh; Hess, Henry; Khargonekar, Pramod P.; Tseng, Yiider

2010-01-01

Abstract The fidelity of the trajectories obtained from video-based particle tracking determines the success of a variety of biophysical techniques, including in situ single cell particle tracking and in vitro motility assays. However, the image acquisition process is complicated by system noise, which causes positioning error in the trajectories derived from image analysis. Here, we explore the possibility of reducing the positioning error by the application of a Kalman filter, a powerful algorithm to estimate the state of a linear dynamic system from noisy measurements. We show that the optimal Kalman filter parameters can be determined in an appropriate experimental setting, and that the Kalman filter can markedly reduce the positioning error while retaining the intrinsic fluctuations of the dynamic process. We believe the Kalman filter can potentially serve as a powerful tool to infer a trajectory of ultra-high fidelity from noisy images, revealing the details of dynamic cellular processes. PMID:20550894

The new agreement of the international RIGA consensus conference on nasal airway function tests.

PubMed

Vogt, K; Bachmann-Harildstad, G; Lintermann, A; Nechyporenko, A; Peters, F; Wernecke, K D

2018-01-21

The report reflects an agreement based on the consensus conference of the International Standardization Committee on the Objective Assessment of the Nasal Airway in Riga, 2nd Nov. 2016. The aim of the conference was to address the existing nasal airway function tests and to take into account physical, mathematical and technical correctness as a base of international standardization as well as the requirements of the Council Directive 93/42/EEC of 14 June 1993 concerning medical devices. Rhinomanometry, acoustic rhinometry, peak nasal inspiratory flow, Odiosoft-Rhino, optical rhinometry, 24-h measurements, computational fluid dynamics, nasometry and the mirrow test were evaluated for important diagnostic criteria, which are the precision of the equipment including calibration and the software applied; validity with sensitivity, specificity, positive and negative predictive values, reliability with intra-individual and inter-individual reproducibility and responsiveness in clinical studies. For rhinomanometry, the logarithmic effective resistance was set as the parameter of high diagnostic relevance. In acoustic rhinometry, the area of interest for the minimal cross-sectional area will need further standardization. Peak nasal inspiratory flow is a reproducible and fast test, which showed a high range of mean values in different studies. The state of the art with computational fluid dynamics for the simulation of the airway still depends on high performance computing hardware and will, after standardization of the software and both the software and hardware for imaging protocols, certainly deliver a better understanding of the nasal airway flux.

Windowed R-PDLF recoupling: a flexible and reliable tool to characterize molecular dynamics.

PubMed

Gansmüller, Axel; Simorre, Jean-Pierre; Hediger, Sabine

2013-09-01

This work focuses on the improvement of the R-PDLF heteronuclear recoupling scheme, a method that allows quantification of molecular dynamics up to the microsecond timescale in heterogeneous materials. We show how the stability of the sequence towards rf-imperfections, one of the main sources of error of this technique, can be improved by the insertion of windows without irradiation into the basic elements of the symmetry-based recoupling sequence. The impact of this modification on the overall performance of the sequence in terms of scaling factor and homonuclear decoupling efficiency is evaluated. This study indicates the experimental conditions for which precise and reliable measurement of dipolar couplings can be obtained using the popular R18(1)(7) recoupling sequence, as well as alternative symmetry-based R sequences suited for fast MAS conditions. An analytical expression for the recoupled dipolar modulation has been derived that applies to a whole class of sequences with similar recoupling properties as R18(1)(7). This analytical expression provides an efficient and precise way to extract dipolar couplings from the experimental dipolar modulation curves. We hereby provide helpful tools and information for tailoring R-PDLF recoupling schemes to specific sample properties and hardware capabilities. This approach is particularly well suited for the study of materials with strong and heterogeneous molecular dynamics where a precise measurement of dipolar couplings is crucial. Copyright © 2013 Elsevier Inc. All rights reserved.

EEG-Based Quantification of Cortical Current Density and Dynamic Causal Connectivity Generalized across Subjects Performing BCI-Monitored Cognitive Tasks

PubMed Central

Courellis, Hristos; Mullen, Tim; Poizner, Howard; Cauwenberghs, Gert; Iversen, John R.

2017-01-01

Quantification of dynamic causal interactions among brain regions constitutes an important component of conducting research and developing applications in experimental and translational neuroscience. Furthermore, cortical networks with dynamic causal connectivity in brain-computer interface (BCI) applications offer a more comprehensive view of brain states implicated in behavior than do individual brain regions. However, models of cortical network dynamics are difficult to generalize across subjects because current electroencephalography (EEG) signal analysis techniques are limited in their ability to reliably localize sources across subjects. We propose an algorithmic and computational framework for identifying cortical networks across subjects in which dynamic causal connectivity is modeled among user-selected cortical regions of interest (ROIs). We demonstrate the strength of the proposed framework using a “reach/saccade to spatial target” cognitive task performed by 10 right-handed individuals. Modeling of causal cortical interactions was accomplished through measurement of cortical activity using (EEG), application of independent component clustering to identify cortical ROIs as network nodes, estimation of cortical current density using cortically constrained low resolution electromagnetic brain tomography (cLORETA), multivariate autoregressive (MVAR) modeling of representative cortical activity signals from each ROI, and quantification of the dynamic causal interaction among the identified ROIs using the Short-time direct Directed Transfer function (SdDTF). The resulting cortical network and the computed causal dynamics among its nodes exhibited physiologically plausible behavior, consistent with past results reported in the literature. This physiological plausibility of the results strengthens the framework's applicability in reliably capturing complex brain functionality, which is required by applications, such as diagnostics and BCI. PMID:28566997

Virtual prototyping of drop test using explicit analysis

NASA Astrophysics Data System (ADS)

Todorov, Georgi; Kamberov, Konstantin

2017-12-01

Increased requirements for reliability and safety, included in contemporary standards and norms, has high impact over new product development. New numerical techniques based on virtual prototyping technology, facilitates imrpoving product development cycle, resutling in reduced time/money spent for this stage as well as increased knowledge about certain failure mechanism. So called "drop test" became nearly a "must" step in development of any human operated product. This study aims to demonstrate dynamic behaviour assessment of a structure under impact loads, based on virtual prototyping using a typical nonlinear analysis - explicit dynamics. An example is presneted, based on a plastic container that is used as cartridge for a dispenser machine exposed to various work conditions. Different drop orientations were analyzed and critical load cases and design weaknesses have been found. Several design modifications have been proposed, based on detailed analyses results review.

Clinical assessment of scapular positioning in musicians: an intertester reliability study.

PubMed

Struyf, Filip; Nijs, Jo; De Coninck, Kris; Giunta, Marco; Mottram, Sarah; Meeusen, Romain

2009-01-01

The reliability of the measurement of the distance between the posterior border of the acromion and the wall and the reliability of the modified lateral scapular slide test have not been studied. Overall, the reliability of the clinical tools used to assess scapular positioning has not been studied in musicians. To examine the intertester reliability of scapular observation and 2 clinical tests for the assessment of scapular positioning in musicians. Intertester reliability study. University research laboratory. Thirty healthy student musicians at a single university. Two assessors performed a standardized observation protocol, the measurement of the distance between the posterior border of the acromion and the wall, and the modified lateral scapular slide test. Each assessor was blinded to the other's findings. The intertester reliability coefficients (kappa) for the observation in relaxed position, during unloaded movement, and during loaded movement were 0.41, 0.63, and 0.36, respectively. The kappa values for the observation of tilting and winging at rest were 0.48 and 0.42, respectively; during unloaded movement, the kappa values were 0.52 and 0.78, respectively; and with a 1-kg load, the kappa values were 0.24 and 0.50, respectively. The intraclass correlation coefficient (ICC) of the measurement of the acromial distance was 0.72 in relaxed position and 0.75 with the participant actively retracting both shoulders. The ICCs for the modified lateral scapular slide test varied between 0.63 and 0.58. Our results demonstrated that the modified lateral scapular slide test was not a reliable tool to assess scapular positioning in these participants. Our data indicated that scapular observation in the relaxed position and during unloaded abduction in the frontal plane was a reliable assessment tool. The reliability of the measurement of the distance between the posterior border of the acromion and the wall in healthy musicians was moderate.

Clinical Assessment of Scapular Positioning in Musicians: An Intertester Reliability Study

PubMed Central

Struyf, Filip; Nijs, Jo; De Coninck, Kris; Giunta, Marco; Mottram, Sarah; Meeusen, Romain

2009-01-01

Abstract Context: The reliability of the measurement of the distance between the posterior border of the acromion and the wall and the reliability of the modified lateral scapular slide test have not been studied. Overall, the reliability of the clinical tools used to assess scapular positioning has not been studied in musicians. Objective: To examine the intertester reliability of scapular observation and 2 clinical tests for the assessment of scapular positioning in musicians. Design: Intertester reliability study. Setting: University research laboratory. Patients or Other Participants: Thirty healthy student musicians at a single university. Main Outcome Measure(s): Two assessors performed a standardized observation protocol, the measurement of the distance between the posterior border of the acromion and the wall, and the modified lateral scapular slide test. Each assessor was blinded to the other's findings. Results: The intertester reliability coefficients (κ) for the observation in relaxed position, during unloaded movement, and during loaded movement were 0.41, 0.63, and 0.36, respectively. The κ values for the observation of tilting and winging at rest were 0.48 and 0.42, respectively; during unloaded movement, the κ values were 0.52 and 0.78, respectively; and with a 1-kg load, the κ values were 0.24 and 0.50, respectively. The intraclass correlation coefficient (ICC) of the measurement of the acromial distance was 0.72 in relaxed position and 0.75 with the participant actively retracting both shoulders. The ICCs for the modified lateral scapular slide test varied between 0.63 and 0.58. Conclusions: Our results demonstrated that the modified lateral scapular slide test was not a reliable tool to assess scapular positioning in these participants. Our data indicated that scapular observation in the relaxed position and during unloaded abduction in the frontal plane was a reliable assessment tool. The reliability of the measurement of the distance between the posterior border of the acromion and the wall in healthy musicians was moderate. PMID:19771291

Catchment-scale groundwater recharge and vegetation water use efficiency

NASA Astrophysics Data System (ADS)

Troch, P. A. A.; Dwivedi, R.; Liu, T.; Meira, A.; Roy, T.; Valdés-Pineda, R.; Durcik, M.; Arciniega, S.; Brena-Naranjo, J. A.

2017-12-01

Precipitation undergoes a two-step partitioning when it falls on the land surface. At the land surface and in the shallow subsurface, rainfall or snowmelt can either runoff as infiltration/saturation excess or quick subsurface flow. The rest will be stored temporarily in the root zone. From the root zone, water can leave the catchment as evapotranspiration or percolate further and recharge deep storage (e.g. fractured bedrock aquifer). Quantifying the average amount of water that recharges deep storage and sustains low flows is extremely challenging, as we lack reliable methods to quantify this flux at the catchment scale. It was recently shown, however, that for semi-arid catchments in Mexico, an index of vegetation water use efficiency, i.e. the Horton index (HI), could predict deep storage dynamics. Here we test this finding using 247 MOPEX catchments across the conterminous US, including energy-limited catchments. Our results show that the observed HI is indeed a reliable predictor of deep storage dynamics in space and time. We further investigate whether the HI can also predict average recharge rates across the conterminous US. We find that the HI can reliably predict the average recharge rate, estimated from the 50th percentile flow of the flow duration curve. Our results compare favorably with estimates of average recharge rates from the US Geological Survey. Previous research has shown that HI can be reliably estimated based on aridity index, mean slope and mean elevation of a catchment (Voepel et al., 2011). We recalibrated Voepel's model and used it to predict the HI for our 247 catchments. We then used these predicted values of the HI to estimate average recharge rates for our catchments, and compared them with those estimated from observed HI. We find that the accuracies of our predictions based on observed and predicted HI are similar. This provides an estimation method of catchment-scale average recharge rates based on easily derived catchment characteristics, such as climate and topography, and free of discharge measurements.

A reliable transmission protocol for ZigBee-based wireless patient monitoring.

PubMed

Chen, Shyr-Kuen; Kao, Tsair; Chan, Chia-Tai; Huang, Chih-Ning; Chiang, Chih-Yen; Lai, Chin-Yu; Tung, Tse-Hua; Wang, Pi-Chung

2012-01-01

Patient monitoring systems are gaining their importance as the fast-growing global elderly population increases demands for caretaking. These systems use wireless technologies to transmit vital signs for medical evaluation. In a multihop ZigBee network, the existing systems usually use broadcast or multicast schemes to increase the reliability of signals transmission; however, both the schemes lead to significantly higher network traffic and end-to-end transmission delay. In this paper, we present a reliable transmission protocol based on anycast routing for wireless patient monitoring. Our scheme automatically selects the closest data receiver in an anycast group as a destination to reduce the transmission latency as well as the control overhead. The new protocol also shortens the latency of path recovery by initiating route recovery from the intermediate routers of the original path. On the basis of a reliable transmission scheme, we implement a ZigBee device for fall monitoring, which integrates fall detection, indoor positioning, and ECG monitoring. When the triaxial accelerometer of the device detects a fall, the current position of the patient is transmitted to an emergency center through a ZigBee network. In order to clarify the situation of the fallen patient, 4-s ECG signals are also transmitted. Our transmission scheme ensures the successful transmission of these critical messages. The experimental results show that our scheme is fast and reliable. We also demonstrate that our devices can seamlessly integrate with the next generation technology of wireless wide area network, worldwide interoperability for microwave access, to achieve real-time patient monitoring.

Quantum Fragment Based ab Initio Molecular Dynamics for Proteins.

PubMed

Liu, Jinfeng; Zhu, Tong; Wang, Xianwei; He, Xiao; Zhang, John Z H

2015-12-08

Developing ab initio molecular dynamics (AIMD) methods for practical application in protein dynamics is of significant interest. Due to the large size of biomolecules, applying standard quantum chemical methods to compute energies for dynamic simulation is computationally prohibitive. In this work, a fragment based ab initio molecular dynamics approach is presented for practical application in protein dynamics study. In this approach, the energy and forces of the protein are calculated by a recently developed electrostatically embedded generalized molecular fractionation with conjugate caps (EE-GMFCC) method. For simulation in explicit solvent, mechanical embedding is introduced to treat protein interaction with explicit water molecules. This AIMD approach has been applied to MD simulations of a small benchmark protein Trpcage (with 20 residues and 304 atoms) in both the gas phase and in solution. Comparison to the simulation result using the AMBER force field shows that the AIMD gives a more stable protein structure in the simulation, indicating that quantum chemical energy is more reliable. Importantly, the present fragment-based AIMD simulation captures quantum effects including electrostatic polarization and charge transfer that are missing in standard classical MD simulations. The current approach is linear-scaling, trivially parallel, and applicable to performing the AIMD simulation of proteins with a large size.

Targeted quantification of functional enzyme dynamics in environmental samples for microbially mediated biogeochemical processes: Targeted quantification of functional enzyme dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Minjing; Gao, Yuqian; Qian, Wei-Jun

Microbially mediated biogeochemical processes are catalyzed by enzymes that control the transformation of carbon, nitrogen, and other elements in environment. The dynamic linkage between enzymes and biogeochemical species transformation has, however, rarely been investigated because of the lack of analytical approaches to efficiently and reliably quantify enzymes and their dynamics in soils and sediments. Herein, we developed a signature peptide-based technique for sensitively quantifying dissimilatory and assimilatory enzymes using nitrate-reducing enzymes in a hyporheic zone sediment as an example. Moreover, the measured changes in enzyme concentration were found to correlate with the nitrate reduction rate in a way different frommore » that inferred from biogeochemical models based on biomass or functional genes as surrogates for functional enzymes. This phenomenon has important implications for understanding and modeling the dynamics of microbial community functions and biogeochemical processes in environments. Our results also demonstrate the importance of enzyme quantification for the identification and interrogation of those biogeochemical processes with low metabolite concentrations as a result of faster enzyme-catalyzed consumption of metabolites than their production. The dynamic enzyme behaviors provide a basis for the development of enzyme-based models to describe the relationship between the microbial community and biogeochemical processes.« less

Development of a short version of the new brief job stress questionnaire.

PubMed

Inoue, Akiomi; Kawakami, Norito; Shimomitsu, Teruichi; Tsutsumi, Akizumi; Haratani, Takashi; Yoshikawa, Toru; Shimazu, Akihito; Odagiri, Yuko

2014-01-01

This study was aimed to investigate the test-retest reliability and validity of a short version of the New Brief Job Stress Questionnaire (New BJSQ) whose scales have one item selected from a standard version. Based on the results from an anonymous web-based questionnaire of occupational health staffs and personnel/labor staffs, we selected higher-priority scales from the standard version. After selecting one item with highest item-total correlation coefficient from each scale, a 23-item questionnaire was developed. A nationally representative survey was administered to Japanese employees (n=1,633) to examine test-retest reliability and validity. Most scales (or items) showed modest but adequate levels of test-retest reliability (r>0.50). Furthermore, job demands and job resources scales (or items) were associated with mental and physical stress reactions while job resources scales (or items) were also associated with positive outcomes. These findings provided a piece of evidence that the short version of the New BJSQ is reliable and valid.

Development of a Short Version of the New Brief Job Stress Questionnaire

PubMed Central

INOUE, Akiomi; KAWAKAMI, Norito; SHIMOMITSU, Teruichi; TSUTSUMI, Akizumi; HARATANI, Takashi; YOSHIKAWA, Toru; SHIMAZU, Akihito; ODAGIRI, Yuko

2014-01-01

This study was aimed to investigate the test-retest reliability and validity of a short version of the New Brief Job Stress Questionnaire (New BJSQ) whose scales have one item selected from a standard version. Based on the results from an anonymous web-based questionnaire of occupational health staffs and personnel/labor staffs, we selected higher-priority scales from the standard version. After selecting one item with highest item-total correlation coefficient from each scale, a 23-item questionnaire was developed. A nationally representative survey was administered to Japanese employees (n=1,633) to examine test-retest reliability and validity. Most scales (or items) showed modest but adequate levels of test-retest reliability (r>0.50). Furthermore, job demands and job resources scales (or items) were associated with mental and physical stress reactions while job resources scales (or items) were also associated with positive outcomes. These findings provided a piece of evidence that the short version of the New BJSQ is reliable and valid. PMID:24975108

Dynamic Involvement of Real World Objects in the IoT: A Consensus-Based Cooperation Approach

PubMed Central

Pilloni, Virginia; Atzori, Luigi; Mallus, Matteo

2017-01-01

A significant role in the Internet of Things (IoT) will be taken by mobile and low-cost unstable devices, which autonomously self-organize and introduce highly dynamic and heterogeneous scenarios for the deployment of distributed applications. This entails the devices to cooperate to dynamically find the suitable combination of their involvement so as to improve the system reliability while following the changes in their status. Focusing on the above scenario, we propose a distributed algorithm for resources allocation that is run by devices that can perform the same task required by the applications, allowing for a flexible and dynamic binding of the requested services with the physical IoT devices. It is based on a consensus approach, which maximizes the lifetime of groups of nodes involved and ensures the fulfillment of the requested Quality of Information (QoI) requirements. Experiments have been conducted with real devices, showing an improvement of device lifetime of more than 20%, with respect to a uniform distribution of tasks. PMID:28257030

Dynamic Involvement of Real World Objects in the IoT: A Consensus-Based Cooperation Approach.

PubMed

Pilloni, Virginia; Atzori, Luigi; Mallus, Matteo

2017-03-01

A significant role in the Internet of Things (IoT) will be taken by mobile and low-cost unstable devices, which autonomously self-organize and introduce highly dynamic and heterogeneous scenarios for the deployment of distributed applications. This entails the devices to cooperate to dynamically find the suitable combination of their involvement so as to improve the system reliability while following the changes in their status. Focusing on the above scenario, we propose a distributed algorithm for resources allocation that is run by devices that can perform the same task required by the applications, allowing for a flexible and dynamic binding of the requested services with the physical IoT devices. It is based on a consensus approach, which maximizes the lifetime of groups of nodes involved and ensures the fulfillment of the requested Quality of Information (QoI) requirements. Experiments have been conducted with real devices, showing an improvement of device lifetime of more than 20 % , with respect to a uniform distribution of tasks.

Intersession reliability of fMRI activation for heat pain and motor tasks

PubMed Central

Quiton, Raimi L.; Keaser, Michael L.; Zhuo, Jiachen; Gullapalli, Rao P.; Greenspan, Joel D.

2014-01-01

As the practice of conducting longitudinal fMRI studies to assess mechanisms of pain-reducing interventions becomes more common, there is a great need to assess the test–retest reliability of the pain-related BOLD fMRI signal across repeated sessions. This study quantitatively evaluated the reliability of heat pain-related BOLD fMRI brain responses in healthy volunteers across 3 sessions conducted on separate days using two measures: (1) intraclass correlation coefficients (ICC) calculated based on signal amplitude and (2) spatial overlap. The ICC analysis of pain-related BOLD fMRI responses showed fair-to-moderate intersession reliability in brain areas regarded as part of the cortical pain network. Areas with the highest intersession reliability based on the ICC analysis included the anterior midcingulate cortex, anterior insula, and second somatosensory cortex. Areas with the lowest intersession reliability based on the ICC analysis also showed low spatial reliability; these regions included pregenual anterior cingulate cortex, primary somatosensory cortex, and posterior insula. Thus, this study found regional differences in pain-related BOLD fMRI response reliability, which may provide useful information to guide longitudinal pain studies. A simple motor task (finger-thumb opposition) was performed by the same subjects in the same sessions as the painful heat stimuli were delivered. Intersession reliability of fMRI activation in cortical motor areas was comparable to previously published findings for both spatial overlap and ICC measures, providing support for the validity of the analytical approach used to assess intersession reliability of pain-related fMRI activation. A secondary finding of this study is that the use of standard ICC alone as a measure of reliability may not be sufficient, as the underlying variance structure of an fMRI dataset can result in inappropriately high ICC values; a method to eliminate these false positive results was used in this study and is recommended for future studies of test–retest reliability. PMID:25161897

Reliability prediction of ontology-based service compositions using Petri net and time series models.

PubMed

Li, Jia; Xia, Yunni; Luo, Xin

2014-01-01

OWL-S, one of the most important Semantic Web service ontologies proposed to date, provides a core ontological framework and guidelines for describing the properties and capabilities of their web services in an unambiguous, computer interpretable form. Predicting the reliability of composite service processes specified in OWL-S allows service users to decide whether the process meets the quantitative quality requirement. In this study, we consider the runtime quality of services to be fluctuating and introduce a dynamic framework to predict the runtime reliability of services specified in OWL-S, employing the Non-Markovian stochastic Petri net (NMSPN) and the time series model. The framework includes the following steps: obtaining the historical response times series of individual service components; fitting these series with a autoregressive-moving-average-model (ARMA for short) and predicting the future firing rates of service components; mapping the OWL-S process into a NMSPN model; employing the predicted firing rates as the model input of NMSPN and calculating the normal completion probability as the reliability estimate. In the case study, a comparison between the static model and our approach based on experimental data is presented and it is shown that our approach achieves higher prediction accuracy.

Measuring metacognitive ability based on science literacy in dynamic electricity topic

NASA Astrophysics Data System (ADS)

Warni; Sunyono; Rosidin

2018-01-01

This study aims to produce an instrument of metacognition ability assessment based on science literacy on theoretically and empirically feasible dynamic electrical material. The feasibility of the assessment instrument includes theoretical validity on material, construction, and language aspects, as well as empirical validity, reliability, difficulty, distinguishing, and distractor indices. The development of assessment instruments refers to the Dick and Carey development model which includes the preliminary study stage, initial product development, validation and revision, and piloting. The instrument was tested to 32 students of class IX in SMP Negeri 20 Bandar Lampung, using the design of One Group Pretest-Postest Design. The result shows that the metacognition ability assessment instrument based on science literacy is feasible theoretically with theoretical validity percentage of 95.44% and empirical validity of 43.75% for the high category, 43.75% for the medium category, and 12.50 % for low category questions; Reliability of assessment instruments of 0.83 high categories; Difficulty level of difficult item is about 31.25% and medium category is equal to 68.75%. Item that has very good distinguishing power is 12.50%, 62.50% for good stage, and medium category is 25.00%; As well as the duplexing function on a matter of multiple choice is 80.00% including good category and 20.00% for medium category.

Parametric diagnosis of the adaptive gas path in the automatic control system of the aircraft engine

NASA Astrophysics Data System (ADS)

Kuznetsova, T. A.

2017-01-01

The paper dwells on the adaptive multimode mathematical model of the gas-turbine aircraft engine (GTE) embedded in the automatic control system (ACS). The mathematical model is based on the throttle performances, and is characterized by high accuracy of engine parameters identification in stationary and dynamic modes. The proposed on-board engine model is the state space linearized low-level simulation. The engine health is identified by the influence of the coefficient matrix. The influence coefficient is determined by the GTE high-level mathematical model based on measurements of gas-dynamic parameters. In the automatic control algorithm, the sum of squares of the deviation between the parameters of the mathematical model and real GTE is minimized. The proposed mathematical model is effectively used for gas path defects detecting in on-line GTE health monitoring. The accuracy of the on-board mathematical model embedded in ACS determines the quality of adaptive control and reliability of the engine. To improve the accuracy of identification solutions and sustainability provision, the numerical method of Monte Carlo was used. The parametric diagnostic algorithm based on the LPτ - sequence was developed and tested. Analysis of the results suggests that the application of the developed algorithms allows achieving higher identification accuracy and reliability than similar models used in practice.

Translation, adaptation and inter-rater reliability of the administration manual for the Fugl-Meyer assessment.

PubMed

Michaelsen, Stella M; Rocha, André S; Knabben, Rodrigo J; Rodrigues, Luciano P; Fernandes, Claudia G C

2011-01-01

Recently, the reliability of the Brazilian version of the Fugl-Meyer Assessment (FMA) was assessed through the scoring given according to observations made by a single evaluator who applied the test. When different raters apply the scale, the reliability may depend on the interpretation given to the assessment sheet. In such cases, a clear administration manual is essential for ensuring homogeneity of application. To translate and adapt the French Canadian version of the FMA administration manual into Brazilian Portuguese and to evaluate the inter-rater reliability when different evaluators apply the FMA on the basis of the information contained in the manual. Eighteen adults (59±10 years) with chronic hemiparesis (38±35 months after a stroke) took part in this study. Eight patients participated in the first part of the study and 10 in the second part. Based on analyzing the results from part 1, an adapted version was developed, in which information and photos were added to illustrate the positions of the patient and evaluator. The inter-rater reliability was assessed using the intraclass correlation coefficient (ICC). The reliability of the FMA based on the adapted version of the manual was excellent for the total motor scores for the upper limbs (ICC=0.98) and lower limbs (ICC=0.90), as well as for movement sense (ICC=0.98) and upper and lower-limb passive range of motion (ICC=0.84 and 0.90, respectively). The reliability was moderate for tactile sensitivity (0.75). The joint pain assessment presented low reliability. The results showed that, except for pain assessment, application of the FMA based on the adapted version of the application manual for Brazilian Portuguese presented adequate inter-rater reliability.

Dynamic Magnification Factor in a Box-Shape Steel Girder

NASA Astrophysics Data System (ADS)

Rahbar-Ranji, A.

2014-01-01

The dynamic effect of moving loads on structures is treated as a dynamic magnification factor when resonant is not imminent. Studies have shown that the calculated magnification factors from field measurements could be higher than the values specified in design codes. It is the main aim of present paper to investigate the applicability and accuracy of a rule-based expression for calculation of dynamic magnification factor for lifting appliances used in marine industry. A steel box shape girder of a crane is considered and transient dynamic analysis using computer code ANSYS is implemented. Dynamic magnification factor is calculated for different loading conditions and compared with rule-based equation. The effects of lifting speeds, acceleration, damping ratio and position of cargo are examined. It is found that rule-based expression underestimate dynamic magnification factor.

Self-organization and positioning of bacterial protein clusters

NASA Astrophysics Data System (ADS)

Murray, Seán M.; Sourjik, Victor

2017-10-01

Many cellular processes require proteins to be precisely positioned within the cell. In some cases this can be attributed to passive mechanisms such as recruitment by other proteins in the cell or by exploiting the curvature of the membrane. However, in bacteria, active self-positioning is likely to play a role in multiple processes, including the positioning of the future site of cell division and cytoplasmic protein clusters. How can such dynamic clusters be formed and positioned? Here, we present a model for the self-organization and positioning of dynamic protein clusters into regularly repeating patterns based on a phase-locked Turing pattern. A single peak in the concentration is always positioned at the midpoint of the model cell, and two peaks are positioned at the midpoint of each half. Furthermore, domain growth results in peak splitting and pattern doubling. We argue that the model may explain the regular positioning of the highly conserved structural maintenance of chromosomes complexes on the bacterial nucleoid and that it provides an attractive mechanism for the self-positioning of dynamic protein clusters in other systems.

Star tracking method based on multiexposure imaging for intensified star trackers.

PubMed

Yu, Wenbo; Jiang, Jie; Zhang, Guangjun

2017-07-20

The requirements for the dynamic performance of star trackers are rapidly increasing with the development of space exploration technologies. However, insufficient knowledge of the angular acceleration has largely decreased the performance of the existing star tracking methods, and star trackers may even fail to track under highly dynamic conditions. This study proposes a star tracking method based on multiexposure imaging for intensified star trackers. The accurate estimation model of the complete motion parameters, including the angular velocity and angular acceleration, is established according to the working characteristic of multiexposure imaging. The estimation of the complete motion parameters is utilized to generate the predictive star image accurately. Therefore, the correct matching and tracking between stars in the real and predictive star images can be reliably accomplished under highly dynamic conditions. Simulations with specific dynamic conditions are conducted to verify the feasibility and effectiveness of the proposed method. Experiments with real starry night sky observation are also conducted for further verification. Simulations and experiments demonstrate that the proposed method is effective and shows excellent performance under highly dynamic conditions.

Work-in-Progress Presented at the Army Symposium on Solid Mechanics, 1980 - Designing for Extremes: Environment, Loading, and Structural Behavior Held at Cape Cod, Massachusetts, 29 September-2 October 1980

DTIC Science & Technology

1980-09-01

relating x’and y’ Figure 2: Basic Laboratory Simulation Model 73 COMPARISON OF COMPUTED AND MEASURED ACCELERATIONS IN A DYNAMICALLY LOADED TACTICAL...Survival (General) Displacements Mines (Ordnance) Telemeter Systems Dynamic Response Models Temperatures Dynamics Moisture Thermal Stresses Energy...probabilistic reliability model for the XM 753 projectile rocket motor to bulkhead joint under extreme loading conditions is constructed. The reliability

Dynamic simulation of knee-joint loading during gait using force-feedback control and surrogate contact modelling.

PubMed

Walter, Jonathan P; Pandy, Marcus G

2017-10-01

The aim of this study was to perform multi-body, muscle-driven, forward-dynamics simulations of human gait using a 6-degree-of-freedom (6-DOF) model of the knee in tandem with a surrogate model of articular contact and force control. A forward-dynamics simulation incorporating position, velocity and contact force-feedback control (FFC) was used to track full-body motion capture data recorded for multiple trials of level walking and stair descent performed by two individuals with instrumented knee implants. Tibiofemoral contact force errors for FFC were compared against those obtained from a standard computed muscle control algorithm (CMC) with a 6-DOF knee contact model (CMC6); CMC with a 1-DOF translating hinge-knee model (CMC1); and static optimization with a 1-DOF translating hinge-knee model (SO). Tibiofemoral joint loads predicted by FFC and CMC6 were comparable for level walking, however FFC produced more accurate results for stair descent. SO yielded reasonable predictions of joint contact loading for level walking but significant differences between model and experiment were observed for stair descent. CMC1 produced the least accurate predictions of tibiofemoral contact loads for both tasks. Our findings suggest that reliable estimates of knee-joint loading may be obtained by incorporating position, velocity and force-feedback control with a multi-DOF model of joint contact in a forward-dynamics simulation of gait. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Systems Reliability Framework for Surface Water Sustainability and Risk Management

NASA Astrophysics Data System (ADS)

Myers, J. R.; Yeghiazarian, L.

2016-12-01

With microbial contamination posing a serious threat to the availability of clean water across the world, it is necessary to develop a framework that evaluates the safety and sustainability of water systems in respect to non-point source fecal microbial contamination. The concept of water safety is closely related to the concept of failure in reliability theory. In water quality problems, the event of failure can be defined as the concentration of microbial contamination exceeding a certain standard for usability of water. It is pertinent in watershed management to know the likelihood of such an event of failure occurring at a particular point in space and time. Microbial fate and transport are driven by environmental processes taking place in complex, multi-component, interdependent environmental systems that are dynamic and spatially heterogeneous, which means these processes and therefore their influences upon microbial transport must be considered stochastic and variable through space and time. A physics-based stochastic model of microbial dynamics is presented that propagates uncertainty using a unique sampling method based on artificial neural networks to produce a correlation between watershed characteristics and spatial-temporal probabilistic patterns of microbial contamination. These results are used to address the question of water safety through several sustainability metrics: reliability, vulnerability, resilience and a composite sustainability index. System reliability is described uniquely though the temporal evolution of risk along watershed points or pathways. Probabilistic resilience describes how long the system is above a certain probability of failure, and the vulnerability metric describes how the temporal evolution of risk changes throughout a hierarchy of failure levels. Additionally our approach allows for the identification of contributions in microbial contamination and uncertainty from specific pathways and sources. We expect that this framework will significantly improve the efficiency and precision of sustainable watershed management strategies through providing a better understanding of how watershed characteristics and environmental parameters affect surface water quality and sustainability. With microbial contamination posing a serious threat to the availability of clean water across the world, it is necessary to develop a framework that evaluates the safety and sustainability of water systems in respect to non-point source fecal microbial contamination. The concept of water safety is closely related to the concept of failure in reliability theory. In water quality problems, the event of failure can be defined as the concentration of microbial contamination exceeding a certain standard for usability of water. It is pertinent in watershed management to know the likelihood of such an event of failure occurring at a particular point in space and time. Microbial fate and transport are driven by environmental processes taking place in complex, multi-component, interdependent environmental systems that are dynamic and spatially heterogeneous, which means these processes and therefore their influences upon microbial transport must be considered stochastic and variable through space and time. A physics-based stochastic model of microbial dynamics is presented that propagates uncertainty using a unique sampling method based on artificial neural networks to produce a correlation between watershed characteristics and spatial-temporal probabilistic patterns of microbial contamination. These results are used to address the question of water safety through several sustainability metrics: reliability, vulnerability, resilience and a composite sustainability index. System reliability is described uniquely though the temporal evolution of risk along watershed points or pathways. Probabilistic resilience describes how long the system is above a certain probability of failure, and the vulnerability metric describes how the temporal evolution of risk changes throughout a hierarchy of failure levels. Additionally our approach allows for the identification of contributions in microbial contamination and uncertainty from specific pathways and sources. We expect that this framework will significantly improve the efficiency and precision of sustainable watershed management strategies through providing a better understanding of how watershed characteristics and environmental parameters affect surface water quality and sustainability.

Genomic characterization reconfirms the taxonomic status of Lactobacillus parakefiri

PubMed Central

TANIZAWA, Yasuhiro; KOBAYASHI, Hisami; KAMINUMA, Eli; SAKAMOTO, Mitsuo; OHKUMA, Moriya; NAKAMURA, Yasukazu; ARITA, Masanori; TOHNO, Masanori

2017-01-01

Whole-genome sequencing was performed for Lactobacillus parakefiri JCM 8573T to confirm its hitherto controversial taxonomic position. Here, we report its first reliable reference genome. Genome-wide metrics, such as average nucleotide identity and digital DNA-DNA hybridization, and phylogenomic analysis based on multiple genes supported its taxonomic status as a distinct species in the genus Lactobacillus. The availability of a reliable genome sequence will aid future investigations on the industrial applications of L. parakefiri in functional foods such as kefir grains. PMID:28748134

Reliable multicast protocol specifications flow control and NACK policy

NASA Technical Reports Server (NTRS)

Callahan, John R.; Montgomery, Todd L.; Whetten, Brian

1995-01-01

This appendix presents the flow and congestion control schemes recommended for RMP and a NACK policy based on the whiteboard tool. Because RMP uses a primarily NACK based error detection scheme, there is no direct feedback path through which receivers can signal losses through low buffer space or congestion. Reliable multicast protocols also suffer from the fact that throughput for a multicast group must be divided among the members of the group. This division is usually very dynamic in nature and therefore does not lend itself well to a priori determination. These facts have led the flow and congestion control schemes of RMP to be made completely orthogonal to the protocol specification. This allows several differing schemes to be used in different environments to produce the best results. As a default, a modified sliding window scheme based on previous algorithms are suggested and described below.

Verification of real sensor motion for a high-dynamic 3D measurement inspection system

NASA Astrophysics Data System (ADS)

Breitbarth, Andreas; Correns, Martin; Zimmermann, Manuel; Zhang, Chen; Rosenberger, Maik; Schambach, Jörg; Notni, Gunther

2017-06-01

Inline three-dimensional measurements are a growing part of optical inspection. Considering increasing production capacities and economic aspects, dynamic measurements under motion are inescapable. Using a sequence of different pattern, like it is generally done in fringe projection systems, relative movements of the measurement object with respect to the 3d sensor between the images of one pattern sequence have to be compensated. Based on the application of fully automated optical inspection of circuit boards at an assembly line, the knowledge of the relative speed of movement between the measurement object and the 3d sensor system should be used inside the algorithms of motion compensation. Optimally, this relative speed is constant over the whole measurement process and consists of only one motion direction to avoid sensor vibrations. The quantified evaluation of this two assumptions and the error impact on the 3d accuracy are content of the research project described by this paper. For our experiments we use a glass etalon with non-transparent circles and transmitted light. Focused on the circle borders, this is one of the most reliable methods to determine subpixel positions using a couple of searching rays. The intersection point of all rays characterize the center of each circle. Based on these circle centers determined with a precision of approximately 1=50 pixel, the motion vector between two images could be calculated and compared with the input motion vector. Overall, the results are used to optimize the weight distribution of the 3d sensor head and reduce non-uniformly vibrations. Finally, there exists a dynamic 3d measurement system with an error of motion vectors about 4 micrometer. Based on this outcome, simulations result in a 3d standard deviation at planar object regions of 6 micrometers. The same system yields a 3d standard deviation of 9 µm without the optimization of weight distribution.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marques da Silva, A; Narciso, L

Purpose: Commercial workstations usually have their own software to calculate dynamic renal functions. However, usually they have low flexibility and subjectivity on delimiting kidney and background areas. The aim of this paper is to present a public domain software, called RenalQuant, capable to semi-automatically draw regions of interest on dynamic renal scintigraphies, extracting data and generating renal function quantification parameters. Methods: The software was developed in Java and written as an ImageJ-based plugin. The preprocessing and segmentation steps include the user’s selection of one time frame with higher activity in kidney’s region, compared with background, and low activity in themore » liver. Next, the chosen time frame is smoothed using a Gaussian low pass spatial filter (σ = 3) for noise reduction and better delimitation of kidneys. The maximum entropy thresholding method is used for segmentation. A background area is automatically placed below each kidney, and the user confirms if these regions are correctly segmented and positioned. Quantitative data are extracted and each renogram and relative renal function (RRF) value is calculated and displayed. Results: RenalQuant plugin was validated using retrospective 20 patients’ 99mTc-DTPA exams, and compared with results produced by commercial workstation software, referred as reference. The renograms intraclass correlation coefficients (ICC) were calculated and false-negative and false-positive RRF values were analyzed. The results showed that ICC values between RenalQuant plugin and reference software for both kidneys’ renograms were higher than 0.75, showing excellent reliability. Conclusion: Our results indicated RenalQuant plugin can be trustingly used to generate renograms, using DICOM dynamic renal scintigraphy exams as input. It is user friendly and user’s interaction occurs at a minimum level. Further studies have to investigate how to increase RRF accuracy and explore how to solve limitations in the segmentation step, mainly when background region has higher activity compared to kidneys. Financial support by CAPES.« less

Global navigation satellite system receiver for weak signals under all dynamic conditions

NASA Astrophysics Data System (ADS)

Ziedan, Nesreen Ibrahim

The ability of the Global Navigation Satellite System (GNSS) receiver to work under weak signal and various dynamic conditions is required in some applications. For example, to provide a positioning capability in wireless devices, or orbit determination of Geostationary and high Earth orbit satellites. This dissertation develops Global Positioning System (GPS) receiver algorithms for such applications. Fifteen algorithms are developed for the GPS C/A signal. They cover all the receiver main functions, which include acquisition, fine acquisition, bit synchronization, code and carrier tracking, and navigation message decoding. They are integrated together, and they can be used in any software GPS receiver. They also can be modified to fit any other GPS or GNSS signals. The algorithms have new capabilities. The processing and memory requirements are considered in the design to allow the algorithms to fit the limited resources of some applications; they do not require any assisting information. Weak signals can be acquired in the presence of strong interfering signals and under high dynamic conditions. The fine acquisition, bit synchronization, and tracking algorithms are based on the Viterbi algorithm and Extended Kalman filter approaches. The tracking algorithms capabilities increase the time to lose lock. They have the ability to adaptively change the integration length and the code delay separation. More than one code delay separation can be used in the same time. Large tracking errors can be detected and then corrected by a re-initialization and an acquisition-like algorithms. Detecting the navigation message is needed to increase the coherent integration; decoding it is needed to calculate the navigation solution. The decoding algorithm utilizes the message structure to enable its decoding for signals with high Bit Error Rate. The algorithms are demonstrated using simulated GPS C/A code signals, and TCXO clocks. The results have shown the algorithms ability to reliably work with 15 dB-Hz signals and acceleration over 6 g.

Exploiting replication in distributed systems

NASA Technical Reports Server (NTRS)

Birman, Kenneth P.; Joseph, T. A.

1989-01-01

Techniques are examined for replicating data and execution in directly distributed systems: systems in which multiple processes interact directly with one another while continuously respecting constraints on their joint behavior. Directly distributed systems are often required to solve difficult problems, ranging from management of replicated data to dynamic reconfiguration in response to failures. It is shown that these problems reduce to more primitive, order-based consistency problems, which can be solved using primitives such as the reliable broadcast protocols. Moreover, given a system that implements reliable broadcast primitives, a flexible set of high-level tools can be provided for building a wide variety of directly distributed application programs.

A novel isoflavone profiling method based on UPLC-PDA-ESI-MS.

PubMed

Zhang, Shuang; Zheng, Zong-Ping; Zeng, Mao-Mao; He, Zhi-Yong; Tao, Guan-Jun; Qin, Fang; Chen, Jie

2017-03-15

A novel non-targeted isoflavone profiling method was developed using the diagnostic fragment-ion-based extension strategy, based on ultra-high performance liquid chromatography coupled with photo-diode array detector and electrospray ionization-mass spectrometry (UPLC-PDA-ESI-MS). 16 types of isoflavones were obtained in positive mode, but only 12 were obtained in negative mode due to the absence of precursor ions. Malonyldaidzin and malonylgenistin glycosylated at the 4'-O position or malonylated at the 4″-O position of glucose were indicated by their retention behavior and fragmentation pattern. Three possible quantification methods in one run based on UPLC-PDA and UPLC-ESI-MS were validated and compared, suggesting that methods based on UPLC-ESI-MS possess remarkable selectivity and sensitivity. Impermissible quantitative deviations induced by the linearity calibration with 400-fold dynamic range was observed for the first time and was recalibrated with a 20-fold dynamic range. These results suggest that isoflavones and their stereoisomers can be simultaneously determined by positive-ion UPLC-ESI-MS in soymilk. Copyright © 2016. Published by Elsevier Ltd.

An ensemble of dynamic neural network identifiers for fault detection and isolation of gas turbine engines.

PubMed

Amozegar, M; Khorasani, K

2016-04-01

In this paper, a new approach for Fault Detection and Isolation (FDI) of gas turbine engines is proposed by developing an ensemble of dynamic neural network identifiers. For health monitoring of the gas turbine engine, its dynamics is first identified by constructing three separate or individual dynamic neural network architectures. Specifically, a dynamic multi-layer perceptron (MLP), a dynamic radial-basis function (RBF) neural network, and a dynamic support vector machine (SVM) are trained to individually identify and represent the gas turbine engine dynamics. Next, three ensemble-based techniques are developed to represent the gas turbine engine dynamics, namely, two heterogeneous ensemble models and one homogeneous ensemble model. It is first shown that all ensemble approaches do significantly improve the overall performance and accuracy of the developed system identification scheme when compared to each of the stand-alone solutions. The best selected stand-alone model (i.e., the dynamic RBF network) and the best selected ensemble architecture (i.e., the heterogeneous ensemble) in terms of their performances in achieving an accurate system identification are then selected for solving the FDI task. The required residual signals are generated by using both a single model-based solution and an ensemble-based solution under various gas turbine engine health conditions. Our extensive simulation studies demonstrate that the fault detection and isolation task achieved by using the residuals that are obtained from the dynamic ensemble scheme results in a significantly more accurate and reliable performance as illustrated through detailed quantitative confusion matrix analysis and comparative studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Molecular Dynamic Simulations of Interaction of an AFM Probe with the Surface of an SCN Sample

NASA Technical Reports Server (NTRS)

Bune, Adris; Kaukler, William; Rose, M. Franklin (Technical Monitor)

2001-01-01

Molecular dynamic (MD) simulations is conducted in order to estimate forces of probe-substrate interaction in the Atomic Force Microscope (AFM). First a review of available molecular dynamic techniques is given. Implementation of MD simulation is based on an object-oriented code developed at the University of Delft. Modeling of the sample material - succinonitrile (SCN) - is based on the Lennard-Jones potentials. For the polystyrene probe an atomic interaction potential is used. Due to object-oriented structure of the code modification of an atomic interaction potential is straight forward. Calculation of melting temperature is used for validation of the code and of the interaction potentials. Various fitting parameters of the probe-substrate interaction potentials are considered, as potentials fitted to certain properties and temperature ranges may not be reliable for the others. This research provides theoretical foundation for an interpretation of actual measurements of an interaction forces using AFM.

A dynamic programming approach to estimate the capacity value of energy storage

DOE PAGES

Sioshansi, Ramteen; Madaeni, Seyed Hossein; Denholm, Paul

2013-09-17

Here, we present a method to estimate the capacity value of storage. Our method uses a dynamic program to model the effect of power system outages on the operation and state of charge of storage in subsequent periods. We combine the optimized dispatch from the dynamic program with estimated system loss of load probabilities to compute a probability distribution for the state of charge of storage in each period. This probability distribution can be used as a forced outage rate for storage in standard reliability-based capacity value estimation methods. Our proposed method has the advantage over existing approximations that itmore » explicitly captures the effect of system shortage events on the state of charge of storage in subsequent periods. We also use a numerical case study, based on five utility systems in the U.S., to demonstrate our technique and compare it to existing approximation methods.« less

Augmented reality and dynamic infrared thermography for perforator mapping in the anterolateral thigh

PubMed Central

Cifuentes, Ignacio Javier; Dagnino, Bruno Leonardo; Salisbury, María Carolina; Perez, María Eliana; Ortega, Claudia; Maldonado, Daniela

2018-01-01

Dynamic infrared thermography (DIRT) has been used for the preoperative mapping of cutaneous perforators. This technique has shown a positive correlation with intraoperative findings. Our aim was to evaluate the accuracy of perforator mapping with DIRT and augmented reality using a portable projector. For this purpose, three volunteers had both of their anterolateral thighs assessed for the presence and location of cutaneous perforators using DIRT. The obtained image of these “hotspots” was projected back onto the thigh and the presence of Doppler signals within a 10-cm diameter from the midpoint between the lateral patella and the anterior superior iliac spine was assessed using a handheld Doppler device. Hotspots were identified in all six anterolateral thighs and were successfully projected onto the skin. The median number of perforators identified within the area of interest was 5 (range, 3–8) and the median time needed to identify them was 3.5 minutes (range, 3.3–4.0 minutes). Every hotspot was correlated to a Doppler sound signal. In conclusion, augmented reality can be a reliable method for transferring the location of perforators identified by DIRT onto the thigh, facilitating its assessment and yielding a reliable map of potential perforators for flap raising. PMID:29788686

Computation of heats of transport in crystalline solids: II

NASA Astrophysics Data System (ADS)

Grout, P. J.; Lidiard, A. B.

2008-10-01

This paper explores the application of classical molecular dynamics to the computation of the heat of transport of Au atoms in a model of solid gold at several elevated temperatures above the Debye temperature. It is assumed that the solid shows vacancy disorder. The work shows that to obtain consistent and reliable results it is necessary (a) to use very small time steps (≈1 fs) in the molecular dynamics integration routine and (b) to take averages over a very large number of vacancy displacements—a number which varies with temperature but which is of the order of 105. The results for the reduced heat of transport for the Au atoms show that: (1) it is positive in sign, i.e. that the diffusion of Au atoms in a temperature gradient is biassed towards the cold region or equivalently that the vacancies tend to migrate towards the hotter region; (2) it is predicted to fall as the average temperature increases and that the variation is closely linear in (1/T); (3) its value at high T relative to the energy of activation for vacancy movement is close to the corresponding ratio of experimental quantities. Analysis of these results indicates that the method and model may allow reliable predictions for other metals having the face centred cubic structure.

High Precision Sunphotometer using Wide Dynamic Range (WDR) Camera Tracking

NASA Astrophysics Data System (ADS)

Liss, J.; Dunagan, S. E.; Johnson, R. R.; Chang, C. S.; LeBlanc, S. E.; Shinozuka, Y.; Redemann, J.; Flynn, C. J.; Segal-Rosenhaimer, M.; Pistone, K.; Kacenelenbogen, M. S.; Fahey, L.

2016-12-01

High Precision Sunphotometer using Wide Dynamic Range (WDR) Camera TrackingThe NASA Ames Sun-photometer-Satellite Group, DOE, PNNL Atmospheric Sciences and Global Change Division, and NASA Goddard's AERONET (AErosol RObotic NETwork) team recently collaborated on the development of a new airborne sunphotometry instrument that provides information on gases and aerosols extending far beyond what can be derived from discrete-channel direct-beam measurements, while preserving or enhancing many of the desirable AATS features (e.g., compactness, versatility, automation, reliability). The enhanced instrument combines the sun-tracking ability of the current 14-Channel NASA Ames AATS-14 with the sky-scanning ability of the ground-based AERONET Sun/sky photometers, while extending both AATS-14 and AERONET capabilities by providing full spectral information from the UV (350 nm) to the SWIR (1,700 nm). Strengths of this measurement approach include many more wavelengths (isolated from gas absorption features) that may be used to characterize aerosols and detailed (oversampled) measurements of the absorption features of specific gas constituents. The Sky Scanning Sun Tracking Airborne Radiometer (3STAR) replicates the radiometer functionality of the AATS-14 instrument but incorporates modern COTS technologies for all instruments subsystems. A 19-channel radiometer bundle design is borrowed from a commercial water column radiance instrument manufactured by Biospherical Instruments of San Diego California (ref, Morrow and Hooker)) and developed using NASA funds under the Small Business Innovative Research (SBIR) program. The 3STAR design also incorporates the latest in robotic motor technology embodied in Rotary actuators from Oriental motor Corp. having better than 15 arc seconds of positioning accuracy. Control system was designed, tested and simulated using a Hybrid-Dynamical modeling methodology. The design also replaces the classic quadrant detector tracking sensor with a wide dynamic range camera that provides a high precision solar position tracking signal as well as an image of the sky in the 45° field of view around the solar axis, which can be of great assistance in flagging data for cloud effects or other factors that might impact data quality.

Effects of climate change and variability on population dynamics in a long-lived shorebird.

PubMed

van de Pol, Martijn; Vindenes, Yngvild; Saether, Bernt-Erik; Engen, Steinar; Ens, Bruno J; Oosterbeek, Kees; Tinbergen, Joost M

2010-04-01

Climate change affects both the mean and variability of climatic variables, but their relative impact on the dynamics of populations is still largely unexplored. Based on a long-term study of the demography of a declining Eurasian Oystercatcher (Haematopus ostralegus) population, we quantify the effect of changes in mean and variance of winter temperature on different vital rates across the life cycle. Subsequently, we quantify, using stochastic stage-structured models, how changes in the mean and variance of this environmental variable affect important characteristics of the future population dynamics, such as the time to extinction. Local mean winter temperature is predicted to strongly increase, and we show that this is likely to increase the population's persistence time via its positive effects on adult survival that outweigh the negative effects that higher temperatures have on fecundity. Interannual variation in winter temperature is predicted to decrease, which is also likely to increase persistence time via its positive effects on adult survival that outweigh the negative effects that lower temperature variability has on fecundity. Overall, a 0.1 degrees C change in mean temperature is predicted to alter median time to extinction by 1.5 times as many years as would a 0.1 degrees C change in the standard deviation in temperature, suggesting that the dynamics of oystercatchers are more sensitive to changes in the mean than in the interannual variability of this climatic variable. Moreover, as climate models predict larger changes in the mean than in the standard deviation of local winter temperature, the effects of future climatic variability on this population's time to extinction are expected to be overwhelmed by the effects of changes in climatic means. We discuss the mechanisms by which climatic variability can either increase or decrease population viability and how this might depend both on species' life histories and on the vital rates affected. This study illustrates that, for making reliable inferences about population consequences in species in which life history changes with age or stage, it is crucial to investigate the impact of climate change on vital rates across the entire life cycle. Disturbingly, such data are unavailable for most species of conservation concern.

Use of measurement theory for operationalization and quantification of psychological constructs in systems dynamics modelling

NASA Astrophysics Data System (ADS)

Fitkov-Norris, Elena; Yeghiazarian, Ara

2016-11-01

The analytical tools available to social scientists have traditionally been adapted from tools originally designed for analysis of natural science phenomena. This article discusses the applicability of systems dynamics - a qualitative based modelling approach, as a possible analysis and simulation tool that bridges the gap between social and natural sciences. After a brief overview of the systems dynamics modelling methodology, the advantages as well as limiting factors of systems dynamics to the potential applications in the field of social sciences and human interactions are discussed. The issues arise with regards to operationalization and quantification of latent constructs at the simulation building stage of the systems dynamics methodology and measurement theory is proposed as a ready and waiting solution to the problem of dynamic model calibration, with a view of improving simulation model reliability and validity and encouraging the development of standardised, modular system dynamics models that can be used in social science research.

Networking switches for smart functions using copper signaling and dynamic heteroleptic complexation.

PubMed

Schmittel, Michael

2018-04-17

This personal frontier account describes our recent progress in networking nanoswitches to generate emergent functions, such as catalytic machinery, and identifies the key impediments in mastering the paradigm shift from pure compounds to smart mixtures. A crucial challenge is the setup of reliable signaling protocols that are based on highly selective metal ion translocation and metal-ligand receptor events.

Long-term potential and actual evapotranspiration of two different forests on the Atlantic Coastal Plain

Treesearch

Devendra Amatya; S. Tian; Z. Dai; Ge Sun

2016-01-01

A reliable estimate of potential evapotranspiration (PET) for a forest ecosystem is critical in ecohydrologic modeling related with water supply, vegetation dynamics, and climate change and yet is a challenging task due to its complexity. Based on long-term on-site measured hydro-climatic data and predictions from earlier validated hydrologic modeling studies...

From positive psychology to psychopathology: the continuum of attention-deficit hyperactivity disorder.

PubMed

Greven, Corina U; Buitelaar, Jan K; Salum, Giovanni A

2018-03-01

Integration of positive psychology into clinical research and treatment has been slow. This integration can be facilitated by the conceptualisation of mental disorders as the high, symptomatic extreme of continuous normal variation. This assumes that there is also a low, positive extreme, which is, however, unchartered territory. This study aims to examine how well current measures capture the low extreme of mental disorder continua, using attention-deficit hyperactivity disorder (ADHD) as an example. The ability of three validated scales to capture ADHD as a continuous trait was examined using Item Response Theory in a sample of 9,882 adolescents from the UK population-representative Twins Early Development Study. These scales were: the Strengths and Weakness of ADHD Symptoms and Normal behaviour scale (SWAN), Strength and Difficulties Questionnaire (SDQ - hyperactivity subscale), and Conners' Parent Rating Scale (Conners). Only the SWAN reliably differentiated interindividual differences between participants lying at any level of the continuous ADHD latent trait, including the extreme low, positive end (z-scores from -3 to +3). The SDQ showed low reliability across the ADHD latent trait. In contrast, the Conners performed best at differentiating individuals scoring at or above the mean to the high symptomatic range (z-scores from 0 to +3). The SWAN was the only measure to provide indicators of 'positive mental health', endorsed in the presence of particularly good attentive abilities. Scales such as the SWAN that reliably capture ADHD as a continuous trait, including the positive end, are important for not missing meaningful variation in population-based studies. Indicators of positive mental health may be helpful in clinical practice, as positive attributes have been shown to directly influence as well as buffer negative effects of psychiatric symptoms. © 2017 Association for Child and Adolescent Mental Health.

Are Competition and Extrinsic Motivation Reliable Predictors of Academic Cheating?

PubMed Central

Orosz, Gábor; Farkas, Dávid; Roland-Lévy, Christine

2013-01-01

Previous studies suggest that extrinsic motivation and competition are reliable predictors of academic cheating. The aim of the present questionnaire study was to separate the effects of motivation- and competition-related variables on academic cheating by Hungarian high school students (N = 620, M = 264, F = 356). Structural equation modeling showed that intrinsic motivation has a negative effect, and amotivation has a positive indirect effect on self-reported academic cheating. In contrast, extrinsic motivation had no significant effect. Indirect positive influence on cheating, based on some characteristics of hypercompetition, was also found, whereas attitudes toward self-developmental competition had a mediated negative influence. Neither constructive nor destructive competitive classroom climate had a significant impact on academic dishonesty. Acceptance of cheating and guilt has significant and direct effect on self-reported cheating. In comparison with them, the effects of motivational and competition-related variables are relatively small, even negligible. These results suggest that extrinsic motivation and competition are not amongst the most reliable predictors of academic cheating behavior. PMID:23450676

Are competition and extrinsic motivation reliable predictors of academic cheating?

PubMed

Orosz, Gábor; Farkas, Dávid; Roland-Lévy, Christine

2013-01-01

Previous studies suggest that extrinsic motivation and competition are reliable predictors of academic cheating. The aim of the present questionnaire study was to separate the effects of motivation- and competition-related variables on academic cheating by Hungarian high school students (N = 620, M = 264, F = 356). Structural equation modeling showed that intrinsic motivation has a negative effect, and amotivation has a positive indirect effect on self-reported academic cheating. In contrast, extrinsic motivation had no significant effect. Indirect positive influence on cheating, based on some characteristics of hypercompetition, was also found, whereas attitudes toward self-developmental competition had a mediated negative influence. Neither constructive nor destructive competitive classroom climate had a significant impact on academic dishonesty. Acceptance of cheating and guilt has significant and direct effect on self-reported cheating. In comparison with them, the effects of motivational and competition-related variables are relatively small, even negligible. These results suggest that extrinsic motivation and competition are not amongst the most reliable predictors of academic cheating behavior.

Building New Bridges between In Vitro and In Vivo in Early Drug Discovery: Where Molecular Modeling Meets Systems Biology.

PubMed

Pearlstein, Robert A; McKay, Daniel J J; Hornak, Viktor; Dickson, Callum; Golosov, Andrei; Harrison, Tyler; Velez-Vega, Camilo; Duca, José

2017-01-01

Cellular drug targets exist within networked function-generating systems whose constituent molecular species undergo dynamic interdependent non-equilibrium state transitions in response to specific perturbations (i.e.. inputs). Cellular phenotypic behaviors are manifested through the integrated behaviors of such networks. However, in vitro data are frequently measured and/or interpreted with empirical equilibrium or steady state models (e.g. Hill, Michaelis-Menten, Briggs-Haldane) relevant to isolated target populations. We propose that cells act as analog computers, "solving" sets of coupled "molecular differential equations" (i.e. represented by populations of interacting species)via "integration" of the dynamic state probability distributions among those populations. Disconnects between biochemical and functional/phenotypic assays (cellular/in vivo) may arise with targetcontaining systems that operate far from equilibrium, and/or when coupled contributions (including target-cognate partner binding and drug pharmacokinetics) are neglected in the analysis of biochemical results. The transformation of drug discovery from a trial-and-error endeavor to one based on reliable design criteria depends on improved understanding of the dynamic mechanisms powering cellular function/dysfunction at the systems level. Here, we address the general mechanisms of molecular and cellular function and pharmacological modulation thereof. We outline a first principles theory on the mechanisms by which free energy is stored and transduced into biological function, and by which biological function is modulated by drug-target binding. We propose that cellular function depends on dynamic counter-balanced molecular systems necessitated by the exponential behavior of molecular state transitions under non-equilibrium conditions, including positive versus negative mass action kinetics and solute-induced perturbations to the hydrogen bonds of solvating water versus kT. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Pull-pull position control of dual motor wire rope transmission.

PubMed

Guo, Quan; Jiao, Zongxia; Yan, Liang; Yu, Qian; Shang, Yaoxing

2016-08-01

Wire rope transmission is very efficient because of the small total moving object mass. The wire rope could only transmit pulling force. Therefore it has to be kept in a tightened state during transmission; in high speed applications the dynamic performance depends on the rope's stiffness, which can be adjusted by the wire rope tension. To improve the system dynamic performance output, this paper proposes a novel pull-pull method based on dual motors connected by wire ropes, for precise, high speed position control applications. The method can regulate target position and wire rope tension simultaneously. Wire ropes remain in a pre-tightening state at all times, which prevents the influence of elasticity and reduces the position tracking error in the changing direction process. Simulations and experiments were conducted; the results indicate that both position precision and superior dynamic performance can be synchronously achieved. The research is relevant to space craft precision pointing instruments.

Dynamically induced cascading failures in power grids.

PubMed

Schäfer, Benjamin; Witthaut, Dirk; Timme, Marc; Latora, Vito

2018-05-17

Reliable functioning of infrastructure networks is essential for our modern society. Cascading failures are the cause of most large-scale network outages. Although cascading failures often exhibit dynamical transients, the modeling of cascades has so far mainly focused on the analysis of sequences of steady states. In this article, we focus on electrical transmission networks and introduce a framework that takes into account both the event-based nature of cascades and the essentials of the network dynamics. We find that transients of the order of seconds in the flows of a power grid play a crucial role in the emergence of collective behaviors. We finally propose a forecasting method to identify critical lines and components in advance or during operation. Overall, our work highlights the relevance of dynamically induced failures on the synchronization dynamics of national power grids of different European countries and provides methods to predict and model cascading failures.

Psychophysiological whole-brain network clustering based on connectivity dynamics analysis in naturalistic conditions.

PubMed

Raz, Gal; Shpigelman, Lavi; Jacob, Yael; Gonen, Tal; Benjamini, Yoav; Hendler, Talma

2016-12-01

We introduce a novel method for delineating context-dependent functional brain networks whose connectivity dynamics are synchronized with the occurrence of a specific psychophysiological process of interest. In this method of context-related network dynamics analysis (CRNDA), a continuous psychophysiological index serves as a reference for clustering the whole-brain into functional networks. We applied CRNDA to fMRI data recorded during the viewing of a sadness-inducing film clip. The method reliably demarcated networks in which temporal patterns of connectivity related to the time series of reported emotional intensity. Our work successfully replicated the link between network connectivity and emotion rating in an independent sample group for seven of the networks. The demarcated networks have clear common functional denominators. Three of these networks overlap with distinct empathy-related networks, previously identified in distinct sets of studies. The other networks are related to sensorimotor processing, language, attention, and working memory. The results indicate that CRNDA, a data-driven method for network clustering that is sensitive to transient connectivity patterns, can productively and reliably demarcate networks that follow psychologically meaningful processes. Hum Brain Mapp 37:4654-4672, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Reimplementation of the Biome-BGC model to simulate successional change.

PubMed

Bond-Lamberty, Ben; Gower, Stith T; Ahl, Douglas E; Thornton, Peter E

2005-04-01

Biogeochemical process models are increasingly employed to simulate current and future forest dynamics, but most simulate only a single canopy type. This limitation means that mixed stands, canopy succession and understory dynamics cannot be modeled, severe handicaps in many forests. The goals of this study were to develop a version of Biome-BGC that supported multiple, interacting vegetation types, and to assess its performance and limitations by comparing modeled results to published data from a 150-year boreal black spruce (Picea mariana (Mill.) BSP) chronosequence in northern Manitoba, Canada. Model data structures and logic were modified to support an arbitrary number of interacting vegetation types; an explicit height calculation was necessary to prioritize radiation and precipitation interception. Two vegetation types, evergreen needle-leaf and deciduous broadleaf, were modeled based on site-specific meteorological and physiological data. The new version of Biome-BGC reliably simulated observed changes in leaf area, net primary production and carbon stocks, and should be useful for modeling the dynamics of mixed-species stands and ecological succession. We discuss the strengths and limitations of Biome-BGC for this application, and note areas in which further work is necessary for reliable simulation of boreal biogeochemical cycling at a landscape scale.

Investigations of FAK inhibitors: a combination of 3D-QSAR, docking, and molecular dynamics simulations studies.

PubMed

Cheng, Peng; Li, Jiaojiao; Wang, Juan; Zhang, Xiaoyun; Zhai, Honglin

2018-05-01

Focal adhesion kinase (FAK) is one kind of tyrosine kinases that modulates integrin and growth factor signaling pathways, which is a promising therapeutic target because of involving in cancer cell migration, proliferation, and survival. To investigate the mechanism between FAK and triazinic inhibitors and design high activity inhibitors, a molecular modeling integrated with 3D-QSAR, molecular docking, molecular dynamics simulations, and binding free energy calculations was performed. The optimum CoMFA and CoMSIA models showed good reliability and satisfactory predictability (with Q 2  = 0.663, R 2  = 0.987, [Formula: see text] = 0.921 and Q 2  = 0.670, R 2  = 0.981, [Formula: see text] = 0.953). Its contour maps could provide structural features to improve inhibitory activity. Furthermore, a good consistency between contour maps, docking, and molecular dynamics simulations strongly demonstrates that the molecular modeling is reliable. Based on it, we designed several new compounds and their inhibitory activities were validated by the molecular models. We expect our studies could bring new ideas to promote the development of novel inhibitors with higher inhibitory activity for FAK.

Exploring Protein Dynamics Space: The Dynasome as the Missing Link between Protein Structure and Function

PubMed Central

Hensen, Ulf; Meyer, Tim; Haas, Jürgen; Rex, René; Vriend, Gert; Grubmüller, Helmut

2012-01-01

Proteins are usually described and classified according to amino acid sequence, structure or function. Here, we develop a minimally biased scheme to compare and classify proteins according to their internal mobility patterns. This approach is based on the notion that proteins not only fold into recurring structural motifs but might also be carrying out only a limited set of recurring mobility motifs. The complete set of these patterns, which we tentatively call the dynasome, spans a multi-dimensional space with axes, the dynasome descriptors, characterizing different aspects of protein dynamics. The unique dynamic fingerprint of each protein is represented as a vector in the dynasome space. The difference between any two vectors, consequently, gives a reliable measure of the difference between the corresponding protein dynamics. We characterize the properties of the dynasome by comparing the dynamics fingerprints obtained from molecular dynamics simulations of 112 proteins but our approach is, in principle, not restricted to any specific source of data of protein dynamics. We conclude that: 1. the dynasome consists of a continuum of proteins, rather than well separated classes. 2. For the majority of proteins we observe strong correlations between structure and dynamics. 3. Proteins with similar function carry out similar dynamics, which suggests a new method to improve protein function annotation based on protein dynamics. PMID:22606222

Jump into a New Fold—A Homology Based Model for the ABCG2/BCRP Multidrug Transporter

PubMed Central

László, Laura; Sarkadi, Balázs

2016-01-01

ABCG2/BCRP is a membrane protein, involved in xenobiotic and endobiotic transport in key pharmacological barriers and drug metabolizing organs, in the protection of stem cells, and in multidrug resistance of cancer. Pharmacogenetic studies implicated the role of ABCG2 in response to widely used medicines and anticancer agents, as well as in gout. Its Q141K variant exhibits decreased functional expression thus increased drug accumulation and decreased urate secretion. Still, there has been no reliable molecular model available for this protein, as the published structures of other ABC transporters could not be properly fitted to the ABCG2 topology and experimental data. The recently published high resolution structure of a close homologue, the ABCG5-ABCG8 heterodimer, revealed a new ABC transporter fold, unique for ABCG proteins. Here we present a structural model of the ABCG2 homodimer based on this fold and detail the experimental results supporting this model. In order to describe the effect of mutations on structure and dynamics, and characterize substrate recognition and cholesterol regulation we performed molecular dynamics simulations using full length ABCG2 protein embedded in a membrane bilayer and in silico docking simulations. Our results show that in the Q141K variant the introduced positive charge diminishes the interaction between the nucleotide binding and transmembrane domains and the R482G variation alters the orientation of transmembrane helices. Moreover, the R482 position, which plays a role the substrate specificity of the transporter, is located in one of the substrate binding pockets identified by the in silico docking calculations. In summary, the ABCG2 model and in silico simulations presented here may have significant impact on understanding drug distribution and toxicity, as well as drug development against cancer chemotherapy resistance or gout. PMID:27741279

Cost-effective solutions to maintaining smart grid reliability

NASA Astrophysics Data System (ADS)

Qin, Qiu

As the aging power systems are increasingly working closer to the capacity and thermal limits, maintaining an sufficient reliability has been of great concern to the government agency, utility companies and users. This dissertation focuses on improving the reliability of transmission and distribution systems. Based on the wide area measurements, multiple model algorithms are developed to diagnose transmission line three-phase short to ground faults in the presence of protection misoperations. The multiple model algorithms utilize the electric network dynamics to provide prompt and reliable diagnosis outcomes. Computational complexity of the diagnosis algorithm is reduced by using a two-step heuristic. The multiple model algorithm is incorporated into a hybrid simulation framework, which consist of both continuous state simulation and discrete event simulation, to study the operation of transmission systems. With hybrid simulation, line switching strategy for enhancing the tolerance to protection misoperations is studied based on the concept of security index, which involves the faulted mode probability and stability coverage. Local measurements are used to track the generator state and faulty mode probabilities are calculated in the multiple model algorithms. FACTS devices are considered as controllers for the transmission system. The placement of FACTS devices into power systems is investigated with a criterion of maintaining a prescribed level of control reconfigurability. Control reconfigurability measures the small signal combined controllability and observability of a power system with an additional requirement on fault tolerance. For the distribution systems, a hierarchical framework, including a high level recloser allocation scheme and a low level recloser placement scheme, is presented. The impacts of recloser placement on the reliability indices is analyzed. Evaluation of reliability indices in the placement process is carried out via discrete event simulation. The reliability requirements are described with probabilities and evaluated from the empirical distributions of reliability indices.

"Unreliability as a threat to understanding psychopathology: The cautionary tale of attentional bias": Correction to Rodebaugh et al. (2016).

PubMed

2016-10-01

Reports an error in "Unreliability as a threat to understanding psychopathology: The cautionary tale of attentional bias" by Thomas L. Rodebaugh, Rachel B. Scullin, Julia K. Langer, David J. Dixon, Jonathan D. Huppert, Amit Bernstein, Ariel Zvielli and Eric J. Lenze ( Journal of Abnormal Psychology , 2016[Aug], Vol 125[6], 840-851). There was an error in the Author Note concerning the support of the MacBrain Face Stimulus Set. The correct statement is provided. (The following abstract of the original article appeared in record 2016-30117-001.) The use of unreliable measures constitutes a threat to our understanding of psychopathology, because advancement of science using both behavioral and biologically oriented measures can only be certain if such measurements are reliable. Two pillars of the National Institute of Mental Health's portfolio-the Research Domain Criteria (RDoC) initiative for psychopathology and the target engagement initiative in clinical trials-cannot succeed without measures that possess the high reliability necessary for tests involving mediation and selection based on individual differences. We focus on the historical lack of reliability of attentional bias measures as an illustration of how reliability can pose a threat to our understanding. Our own data replicate previous findings of poor reliability for traditionally used scores, which suggests a serious problem with the ability to test theories regarding attentional bias. This lack of reliability may also suggest problems with the assumption (in both theory and the formula for the scores) that attentional bias is consistent and stable across time. In contrast, measures accounting for attention as a dynamic process in time show good reliability in our data. The field is sorely in need of research reporting findings and reliability for attentional bias scores using multiple methods, including those focusing on dynamic processes over time. We urge researchers to test and report reliability of all measures, considering findings of low reliability not just as a nuisance but as an opportunity to modify and improve upon the underlying theory. Full assessment of reliability of measures will maximize the possibility that RDoC (and psychological science more generally) will succeed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

A Motor Speech Assessment for Children with Severe Speech Disorders: Reliability and Validity Evidence

ERIC Educational Resources Information Center

Strand, Edythe A.; McCauley, Rebecca J.; Weigand, Stephen D.; Stoeckel, Ruth E.; Baas, Becky S.

2013-01-01

Purpose: In this article, the authors report reliability and validity evidence for the Dynamic Evaluation of Motor Speech Skill (DEMSS), a new test that uses dynamic assessment to aid in the differential diagnosis of childhood apraxia of speech (CAS). Method: Participants were 81 children between 36 and 79 months of age who were referred to the…

The Achievement of Therapeutic Objectives Scale: Interrater Reliability and Sensitivity to Change in Short-Term Dynamic Psychotherapy and Cognitive Therapy

ERIC Educational Resources Information Center

Valen, Jakob; Ryum, Truls; Svartberg, Martin; Stiles, Tore C.; McCullough, Leigh

2011-01-01

This study examined interrater reliability and sensitivity to change of the Achievement of Therapeutic Objectives Scale (ATOS; McCullough, Larsen, et al., 2003) in short-term dynamic psychotherapy (STDP) and cognitive therapy (CT). The ATOS is a process scale originally developed to assess patients' achievements of treatment objectives in STDP,…

Reliability analysis and fault-tolerant system development for a redundant strapdown inertial measurement unit. [inertial platforms

NASA Technical Reports Server (NTRS)

Motyka, P.

1983-01-01

A methodology is developed and applied for quantitatively analyzing the reliability of a dual, fail-operational redundant strapdown inertial measurement unit (RSDIMU). A Markov evaluation model is defined in terms of the operational states of the RSDIMU to predict system reliability. A 27 state model is defined based upon a candidate redundancy management system which can detect and isolate a spectrum of failure magnitudes. The results of parametric studies are presented which show the effect on reliability of the gyro failure rate, both the gyro and accelerometer failure rates together, false alarms, probability of failure detection, probability of failure isolation, and probability of damage effects and mission time. A technique is developed and evaluated for generating dynamic thresholds for detecting and isolating failures of the dual, separated IMU. Special emphasis is given to the detection of multiple, nonconcurrent failures. Digital simulation time histories are presented which show the thresholds obtained and their effectiveness in detecting and isolating sensor failures.

Electron-Ion Dynamics with Time-Dependent Density Functional Theory: Towards Predictive Solar Cell Modeling: Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maitra, Neepa

2016-07-14

This project investigates the accuracy of currently-used functionals in time-dependent density functional theory, which is today routinely used to predict and design materials and computationally model processes in solar energy conversion. The rigorously-based electron-ion dynamics method developed here sheds light on traditional methods and overcomes challenges those methods have. The fundamental research undertaken here is important for building reliable and practical methods for materials discovery. The ultimate goal is to use these tools for the computational design of new materials for solar cell devices of high efficiency.

Real-time motion artifacts compensation of ToF sensors data on GPU

NASA Astrophysics Data System (ADS)

Lefloch, Damien; Hoegg, Thomas; Kolb, Andreas

2013-05-01

Over the last decade, ToF sensors attracted many computer vision and graphics researchers. Nevertheless, ToF devices suffer from severe motion artifacts for dynamic scenes as well as low-resolution depth data which strongly justifies the importance of a valid correction. To counterbalance this effect, a pre-processing approach is introduced to greatly improve range image data on dynamic scenes. We first demonstrate the robustness of our approach using simulated data to finally validate our method using sensor range data. Our GPU-based processing pipeline enhances range data reliability in real-time.

Convolutional neural network guided blue crab knuckle detection for autonomous crab meat picking machine

NASA Astrophysics Data System (ADS)

Wang, Dongyi; Vinson, Robert; Holmes, Maxwell; Seibel, Gary; Tao, Yang

2018-04-01

The Atlantic blue crab is among the highest-valued seafood found in the American Eastern Seaboard. Currently, the crab processing industry is highly dependent on manual labor. However, there is great potential for vision-guided intelligent machines to automate the meat picking process. Studies show that the back-fin knuckles are robust features containing information about a crab's size, orientation, and the position of the crab's meat compartments. Our studies also make it clear that detecting the knuckles reliably in images is challenging due to the knuckle's small size, anomalous shape, and similarity to joints in the legs and claws. An accurate and reliable computer vision algorithm was proposed to detect the crab's back-fin knuckles in digital images. Convolutional neural networks (CNNs) can localize rough knuckle positions with 97.67% accuracy, transforming a global detection problem into a local detection problem. Compared to the rough localization based on human experience or other machine learning classification methods, the CNN shows the best localization results. In the rough knuckle position, a k-means clustering method is able to further extract the exact knuckle positions based on the back-fin knuckle color features. The exact knuckle position can help us to generate a crab cutline in XY plane using a template matching method. This is a pioneering research project in crab image analysis and offers advanced machine intelligence for automated crab processing.

A Passive System Reliability Analysis for a Station Blackout

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brunett, Acacia; Bucknor, Matthew; Grabaskas, David

2015-05-03

The latest iterations of advanced reactor designs have included increased reliance on passive safety systems to maintain plant integrity during unplanned sequences. While these systems are advantageous in reducing the reliance on human intervention and availability of power, the phenomenological foundations on which these systems are built require a novel approach to a reliability assessment. Passive systems possess the unique ability to fail functionally without failing physically, a result of their explicit dependency on existing boundary conditions that drive their operating mode and capacity. Argonne National Laboratory is performing ongoing analyses that demonstrate various methodologies for the characterization of passivemore » system reliability within a probabilistic framework. Two reliability analysis techniques are utilized in this work. The first approach, the Reliability Method for Passive Systems, provides a mechanistic technique employing deterministic models and conventional static event trees. The second approach, a simulation-based technique, utilizes discrete dynamic event trees to treat time- dependent phenomena during scenario evolution. For this demonstration analysis, both reliability assessment techniques are used to analyze an extended station blackout in a pool-type sodium fast reactor (SFR) coupled with a reactor cavity cooling system (RCCS). This work demonstrates the entire process of a passive system reliability analysis, including identification of important parameters and failure metrics, treatment of uncertainties and analysis of results.« less

GaN HEMTs with p-GaN gate: field- and time-dependent degradation

NASA Astrophysics Data System (ADS)

Meneghesso, G.; Meneghini, M.; Rossetto, I.; Canato, E.; Bartholomeus, J.; De Santi, C.; Trivellin, N.; Zanoni, E.

2017-02-01

GaN-HEMTs with p-GaN gate have recently demonstrated to be excellent normally-off devices for application in power conversion systems, thanks to the high and robust threshold voltage (VTH>1 V), the high breakdown voltage, and the low dynamic Ron increase. For this reason, studying the stability and reliability of these devices under high stress conditions is of high importance. This paper reports on our most recent results on the field- and time-dependent degradation of GaN-HEMTs with p-GaN gate submitted to stress with positive gate bias. Based on combined step-stress experiments, constant voltage stress and electroluminescence testing we demonstrated that: (i) when submitted to high/positive gate stress, the transistors may show a negative threshold voltage shift, that is ascribed to the injection of holes from the gate metal towards the p-GaN/AlGaN interface; (ii) in a step-stress experiment, the analyzed commercial devices fail at gate voltages higher than 9-10 V, due to the extremely high electric field over the p-GaN/AlGaN stack; (iii) constant voltage stress tests indicate that the failure is also time-dependent and Weibull distributed. The several processes that can explain the time-dependent failure are discussed in the following.

Neurophysiology underlying influence of stimulus reliability on audiovisual integration.

PubMed

Shatzer, Hannah; Shen, Stanley; Kerlin, Jess R; Pitt, Mark A; Shahin, Antoine J

2018-01-24

We tested the predictions of the dynamic reweighting model (DRM) of audiovisual (AV) speech integration, which posits that spectrotemporally reliable (informative) AV speech stimuli induce a reweighting of processing from low-level to high-level auditory networks. This reweighting decreases sensitivity to acoustic onsets and in turn increases tolerance to AV onset asynchronies (AVOA). EEG was recorded while subjects watched videos of a speaker uttering trisyllabic nonwords that varied in spectrotemporal reliability and asynchrony of the visual and auditory inputs. Subjects judged the stimuli as in-sync or out-of-sync. Results showed that subjects exhibited greater AVOA tolerance for non-blurred than blurred visual speech and for less than more degraded acoustic speech. Increased AVOA tolerance was reflected in reduced amplitude of the P1-P2 auditory evoked potentials, a neurophysiological indication of reduced sensitivity to acoustic onsets and successful AV integration. There was also sustained visual alpha band (8-14 Hz) suppression (desynchronization) following acoustic speech onsets for non-blurred vs. blurred visual speech, consistent with continuous engagement of the visual system as the speech unfolds. The current findings suggest that increased spectrotemporal reliability of acoustic and visual speech promotes robust AV integration, partly by suppressing sensitivity to acoustic onsets, in support of the DRM's reweighting mechanism. Increased visual signal reliability also sustains the engagement of the visual system with the auditory system to maintain alignment of information across modalities. © 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Adaptive Control Based Harvesting Strategy for a Predator-Prey Dynamical System.

PubMed

Sen, Moitri; Simha, Ashutosh; Raha, Soumyendu

2018-04-23

This paper deals with designing a harvesting control strategy for a predator-prey dynamical system, with parametric uncertainties and exogenous disturbances. A feedback control law for the harvesting rate of the predator is formulated such that the population dynamics is asymptotically stabilized at a positive operating point, while maintaining a positive, steady state harvesting rate. The hierarchical block strict feedback structure of the dynamics is exploited in designing a backstepping control law, based on Lyapunov theory. In order to account for unknown parameters, an adaptive control strategy has been proposed in which the control law depends on an adaptive variable which tracks the unknown parameter. Further, a switching component has been incorporated to robustify the control performance against bounded disturbances. Proofs have been provided to show that the proposed adaptive control strategy ensures asymptotic stability of the dynamics at a desired operating point, as well as exact parameter learning in the disturbance-free case and learning with bounded error in the disturbance prone case. The dynamics, with uncertainty in the death rate of the predator, subjected to a bounded disturbance has been simulated with the proposed control strategy.

Diffusion-Based Model for Synaptic Molecular Communication Channel.

PubMed

Khan, Tooba; Bilgin, Bilgesu A; Akan, Ozgur B

2017-06-01

Computational methods have been extensively used to understand the underlying dynamics of molecular communication methods employed by nature. One very effective and popular approach is to utilize a Monte Carlo simulation. Although it is very reliable, this method can have a very high computational cost, which in some cases renders the simulation impractical. Therefore, in this paper, for the special case of an excitatory synaptic molecular communication channel, we present a novel mathematical model for the diffusion and binding of neurotransmitters that takes into account the effects of synaptic geometry in 3-D space and re-absorption of neurotransmitters by the transmitting neuron. Based on this model we develop a fast deterministic algorithm, which calculates expected value of the output of this channel, namely, the amplitude of excitatory postsynaptic potential (EPSP), for given synaptic parameters. We validate our algorithm by a Monte Carlo simulation, which shows total agreement between the results of the two methods. Finally, we utilize our model to quantify the effects of variation in synaptic parameters, such as position of release site, receptor density, size of postsynaptic density, diffusion coefficient, uptake probability, and number of neurotransmitters in a vesicle, on maximum number of bound receptors that directly affect the peak amplitude of EPSP.

Validity and reliability of GPS and LPS for measuring distances covered and sprint mechanical properties in team sports.

PubMed

Hoppe, Matthias W; Baumgart, Christian; Polglaze, Ted; Freiwald, Jürgen

2018-01-01

This study aimed to investigate the validity and reliability of global (GPS) and local (LPS) positioning systems for measuring distances covered and sprint mechanical properties in team sports. Here, we evaluated two recently released 18 Hz GPS and 20 Hz LPS technologies together with one established 10 Hz GPS technology. Six male athletes (age: 27±2 years; VO2max: 48.8±4.7 ml/min/kg) performed outdoors on 10 trials of a team sport-specific circuit that was equipped with double-light timing gates. The circuit included various walking, jogging, and sprinting sections that were performed either in straight-lines or with changes of direction. During the circuit, athletes wore two devices of each positioning system. From the reported and filtered velocity data, the distances covered and sprint mechanical properties (i.e., the theoretical maximal horizontal velocity, force, and power output) were computed. The sprint mechanical properties were modeled via an inverse dynamic approach applied to the center of mass. The validity was determined by comparing the measured and criterion data via the typical error of estimate (TEE), whereas the reliability was examined by comparing the two devices of each technology (i.e., the between-device reliability) via the coefficient of variation (CV). Outliers due to measurement errors were statistically identified and excluded from validity and reliability analyses. The 18 Hz GPS showed better validity and reliability for determining the distances covered (TEE: 1.6-8.0%; CV: 1.1-5.1%) and sprint mechanical properties (TEE: 4.5-14.3%; CV: 3.1-7.5%) than the 10 Hz GPS (TEE: 3.0-12.9%; CV: 2.5-13.0% and TEE: 4.1-23.1%; CV: 3.3-20.0%). However, the 20 Hz LPS demonstrated superior validity and reliability overall (TEE: 1.0-6.0%; CV: 0.7-5.0% and TEE: 2.1-9.2%; CV: 1.6-7.3%). For the 10 Hz GPS, 18 Hz GPS, and 20 Hz LPS, the relative loss of data sets due to measurement errors was 10.0%, 20.0%, and 15.8%, respectively. This study shows that 18 Hz GPS has enhanced validity and reliability for determining movement patterns in team sports compared to 10 Hz GPS, whereas 20 Hz LPS had superior validity and reliability overall. However, compared to 10 Hz GPS, 18 Hz GPS and 20 Hz LPS technologies had more outliers due to measurement errors, which limits their practical applications at this time.

Inconsistencies in Numerical Simulations of Dynamical Systems Using Interval Arithmetic

NASA Astrophysics Data System (ADS)

Nepomuceno, Erivelton G.; Peixoto, Márcia L. C.; Martins, Samir A. M.; Rodrigues, Heitor M.; Perc, Matjaž

Over the past few decades, interval arithmetic has been attracting widespread interest from the scientific community. With the expansion of computing power, scientific computing is encountering a noteworthy shift from floating-point arithmetic toward increased use of interval arithmetic. Notwithstanding the significant reliability of interval arithmetic, this paper presents a theoretical inconsistency in a simulation of dynamical systems using a well-known implementation of arithmetic interval. We have observed that two natural interval extensions present an empty intersection during a finite time range, which is contrary to the fundamental theorem of interval analysis. We have proposed a procedure to at least partially overcome this problem, based on the union of the two generated pseudo-orbits. This paper also shows a successful case of interval arithmetic application in the reduction of interval width size on the simulation of discrete map. The implications of our findings on the reliability of scientific computing using interval arithmetic have been properly addressed using two numerical examples.

Probabilistic assessment of dynamic system performance. Part 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 safemore » 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.« less

Dynamic Characteristics of Positive Pulsed Dielectric Barrier Discharge for Ozone Generation in Air

NASA Astrophysics Data System (ADS)

Wei, Linsheng; Peng, Bangfa; Li, Ming; Zhang, Yafang; Hu, Zhaoji

2016-02-01

A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge (DBD) using parallel-plate reactor in air. The electron energy conservation equation is coupled to the electron continuity equation, the heavy species continuity equation, and Poisson's equation for a better description. The reliability of the model is experimentally confirmed. The model can be used to predict the temporal and spatial evolution of species, as well as streamer propagation. The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche. Streamer propagation velocity is about 5.26 × 104 m/s from anode to cathode in the simulated condition. The primary positive ion, negative ion, and excited species are O2+, O3- and O2(1Δg) in pulsed DBD in air, respectively. N2O has the largest density among nitrogen oxides. e and N2+ densities in the streamer head increase gradually to maximum values with the development of the streamer. Meanwhile, the O2+, O, O3, N2(A3Σ) and N2O densities reach maximum values in the vicinity of the anode. supported by National Natural Science Foundation of China (Nos. 51366012 and 11105067), Jiangxi Province Young Scientists (Jinggang Star) Cultivation Plan of China (No. 20133BCB23008), Natural Science Foundation of Jiangxi, China (No. 20151BAB206047) and Jiangxi Province Higher School Science and Technology Landing Plan of China (No. KJLD-14015)

RGCA: A Reliable GPU Cluster Architecture for Large-Scale Internet of Things Computing Based on Effective Performance-Energy Optimization

PubMed Central

Chen, Qingkui; Zhao, Deyu; Wang, Jingjuan

2017-01-01

This paper aims to develop a low-cost, high-performance and high-reliability computing system to process large-scale data using common data mining algorithms in the Internet of Things (IoT) computing environment. Considering the characteristics of IoT data processing, similar to mainstream high performance computing, we use a GPU (Graphics Processing Unit) cluster to achieve better IoT services. Firstly, we present an energy consumption calculation method (ECCM) based on WSNs. Then, using the CUDA (Compute Unified Device Architecture) Programming model, we propose a Two-level Parallel Optimization Model (TLPOM) which exploits reasonable resource planning and common compiler optimization techniques to obtain the best blocks and threads configuration considering the resource constraints of each node. The key to this part is dynamic coupling Thread-Level Parallelism (TLP) and Instruction-Level Parallelism (ILP) to improve the performance of the algorithms without additional energy consumption. Finally, combining the ECCM and the TLPOM, we use the Reliable GPU Cluster Architecture (RGCA) to obtain a high-reliability computing system considering the nodes’ diversity, algorithm characteristics, etc. The results show that the performance of the algorithms significantly increased by 34.1%, 33.96% and 24.07% for Fermi, Kepler and Maxwell on average with TLPOM and the RGCA ensures that our IoT computing system provides low-cost and high-reliability services. PMID:28777325

RGCA: A Reliable GPU Cluster Architecture for Large-Scale Internet of Things Computing Based on Effective Performance-Energy Optimization.

PubMed

Fang, Yuling; Chen, Qingkui; Xiong, Neal N; Zhao, Deyu; Wang, Jingjuan

2017-08-04

This paper aims to develop a low-cost, high-performance and high-reliability computing system to process large-scale data using common data mining algorithms in the Internet of Things (IoT) computing environment. Considering the characteristics of IoT data processing, similar to mainstream high performance computing, we use a GPU (Graphics Processing Unit) cluster to achieve better IoT services. Firstly, we present an energy consumption calculation method (ECCM) based on WSNs. Then, using the CUDA (Compute Unified Device Architecture) Programming model, we propose a Two-level Parallel Optimization Model (TLPOM) which exploits reasonable resource planning and common compiler optimization techniques to obtain the best blocks and threads configuration considering the resource constraints of each node. The key to this part is dynamic coupling Thread-Level Parallelism (TLP) and Instruction-Level Parallelism (ILP) to improve the performance of the algorithms without additional energy consumption. Finally, combining the ECCM and the TLPOM, we use the Reliable GPU Cluster Architecture (RGCA) to obtain a high-reliability computing system considering the nodes' diversity, algorithm characteristics, etc. The results show that the performance of the algorithms significantly increased by 34.1%, 33.96% and 24.07% for Fermi, Kepler and Maxwell on average with TLPOM and the RGCA ensures that our IoT computing system provides low-cost and high-reliability services.

Real-time single-frequency GPS/MEMS-IMU attitude determination of lightweight UAVs.

PubMed

Eling, Christian; Klingbeil, Lasse; Kuhlmann, Heiner

2015-10-16

In this paper, a newly-developed direct georeferencing system for the guidance, navigation and control of lightweight unmanned aerial vehicles (UAVs), having a weight limit of 5 kg and a size limit of 1.5 m, and for UAV-based surveying and remote sensing applications is presented. The system is intended to provide highly accurate positions and attitudes (better than 5 cm and 0.5°) in real time, using lightweight components. The main focus of this paper is on the attitude determination with the system. This attitude determination is based on an onboard single-frequency GPS baseline, MEMS (micro-electro-mechanical systems) inertial sensor readings, magnetic field observations and a 3D position measurement. All of this information is integrated in a sixteen-state error space Kalman filter. Special attention in the algorithm development is paid to the carrier phase ambiguity resolution of the single-frequency GPS baseline observations. We aim at a reliable and instantaneous ambiguity resolution, since the system is used in urban areas, where frequent losses of the GPS signal lock occur and the GPS measurement conditions are challenging. Flight tests and a comparison to a navigation-grade inertial navigation system illustrate the performance of the developed system in dynamic situations. Evaluations show that the accuracies of the system are 0.05° for the roll and the pitch angle and 0.2° for the yaw angle. The ambiguities of the single-frequency GPS baseline can be resolved instantaneously in more than 90% of the cases.

Fluorescence ELISA based on glucose oxidase-mediated fluorescence quenching of quantum dots for highly sensitive detection of Hepatitis B.

PubMed

Wu, Yunqing; Zeng, Lifeng; Xiong, Ying; Leng, Yuankui; Wang, Hui; Xiong, Yonghua

2018-05-01

Herein, we present a novel sandwich fluorescence enzyme linked immunosorbent assay (ELISA) for highly sensitive detection of Hepatitis B virus surface antigen (HBsAg) based on glucose oxidase (GOx)-induced fluorescence quenching of mercaptopropionic acid-modified CdTe quantum dots (MPA-QDs). In this system, hydrogen peroxide (H 2 O 2 ) sensitive MPA-QDs was used as a signal output, and glucose oxidase (GOx) was used as label which can generate H 2 O 2 via catalytic oxidation of glucose. The proposed method showed dynamic linear detection of HBsAg both in the range of 47pgmL -1 ~ 380pgmL -1 and 0.75ngmL -1 ~ 12.12ngmL -1 . The detection limit of the proposed fluorescence ELISA was 1.16pgmL -1 , which was approximately 430-fold lower than that of horseradish peroxidase (HRP)-based conventional ELISA. The average recoveries for HBsAg-spiked serum samples ranged from 98.0% to 126.8% with the relative standard derivation below 10%, thus indicating acceptable precision and high reproducibility of the proposed fluorescence ELISA for HBsAg detection. Additionally, the developed method showed no false positive results analyzing 35 real HBsAg-negative serum samples, and exhibited excellent agreement (R 2 =0.9907) with a commercial time-resolved fluorescence immunoassay (TRFIA) kit for detecting 31 HBsAg-positive serum samples. In summary, the proposed method based on fluorescence quenching of H 2 O 2 sensitive QDs is considerably to be an excellent biodetection platform with ultrahigh sensitivity, good accuracy and excellent reliability. Copyright © 2018 Elsevier B.V. All rights reserved.

Reliability based design including future tests and multiagent approaches

NASA Astrophysics Data System (ADS)

Villanueva, Diane

The initial stages of reliability-based design optimization involve the formulation of objective functions and constraints, and building a model to estimate the reliability of the design with quantified uncertainties. However, even experienced hands often overlook important objective functions and constraints that affect the design. In addition, uncertainty reduction measures, such as tests and redesign, are often not considered in reliability calculations during the initial stages. This research considers two areas that concern the design of engineering systems: 1) the trade-off of the effect of a test and post-test redesign on reliability and cost and 2) the search for multiple candidate designs as insurance against unforeseen faults in some designs. In this research, a methodology was developed to estimate the effect of a single future test and post-test redesign on reliability and cost. The methodology uses assumed distributions of computational and experimental errors with re-design rules to simulate alternative future test and redesign outcomes to form a probabilistic estimate of the reliability and cost for a given design. Further, it was explored how modeling a future test and redesign provides a company an opportunity to balance development costs versus performance by simultaneously designing the design and the post-test redesign rules during the initial design stage. The second area of this research considers the use of dynamic local surrogates, or surrogate-based agents, to locate multiple candidate designs. Surrogate-based global optimization algorithms often require search in multiple candidate regions of design space, expending most of the computation needed to define multiple alternate designs. Thus, focusing on solely locating the best design may be wasteful. We extended adaptive sampling surrogate techniques to locate multiple optima by building local surrogates in sub-regions of the design space to identify optima. The efficiency of this method was studied, and the method was compared to other surrogate-based optimization methods that aim to locate the global optimum using two two-dimensional test functions, a six-dimensional test function, and a five-dimensional engineering example.

Estimating spatio-temporal dynamics of stream total phosphate concentration by soft computing techniques.

PubMed

Chang, Fi-John; Chen, Pin-An; Chang, Li-Chiu; Tsai, Yu-Hsuan

2016-08-15

This study attempts to model the spatio-temporal dynamics of total phosphate (TP) concentrations along a river for effective hydro-environmental management. We propose a systematical modeling scheme (SMS), which is an ingenious modeling process equipped with a dynamic neural network and three refined statistical methods, for reliably predicting the TP concentrations along a river simultaneously. Two different types of artificial neural network (BPNN-static neural network; NARX network-dynamic neural network) are constructed in modeling the dynamic system. The Dahan River in Taiwan is used as a study case, where ten-year seasonal water quality data collected at seven monitoring stations along the river are used for model training and validation. Results demonstrate that the NARX network can suitably capture the important dynamic features and remarkably outperforms the BPNN model, and the SMS can effectively identify key input factors, suitably overcome data scarcity, significantly increase model reliability, satisfactorily estimate site-specific TP concentration at seven monitoring stations simultaneously, and adequately reconstruct seasonal TP data into a monthly scale. The proposed SMS can reliably model the dynamic spatio-temporal water pollution variation in a river system for missing, hazardous or costly data of interest. Copyright © 2016 Elsevier B.V. All rights reserved.

Privacy Preserved and Secured Reliable Routing Protocol for Wireless Mesh Networks.

PubMed

Meganathan, Navamani Thandava; Palanichamy, Yogesh

2015-01-01

Privacy preservation and security provision against internal attacks in wireless mesh networks (WMNs) are more demanding than in wired networks due to the open nature and mobility of certain nodes in the network. Several schemes have been proposed to preserve privacy and provide security in WMNs. To provide complete privacy protection in WMNs, the properties of unobservability, unlinkability, and anonymity are to be ensured during route discovery. These properties can be achieved by implementing group signature and ID-based encryption schemes during route discovery. Due to the characteristics of WMNs, it is more vulnerable to many network layer attacks. Hence, a strong protection is needed to avoid these attacks and this can be achieved by introducing a new Cross-Layer and Subject Logic based Dynamic Reputation (CLSL-DR) mechanism during route discovery. In this paper, we propose a new Privacy preserved and Secured Reliable Routing (PSRR) protocol for WMNs. This protocol incorporates group signature, ID-based encryption schemes, and CLSL-DR mechanism to ensure strong privacy, security, and reliability in WMNs. Simulation results prove this by showing better performance in terms of most of the chosen parameters than the existing protocols.

Internet-based videoconferencing and data collaboration for the imaging community.

PubMed

Poon, David P; Langkals, John W; Giesel, Frederik L; Knopp, Michael V; von Tengg-Kobligk, Hendrik

2011-01-01

Internet protocol-based digital data collaboration with videoconferencing is not yet well utilized in the imaging community. Videoconferencing, combined with proven low-cost solutions, can provide reliable functionality and speed, which will improve rapid, time-saving, and cost-effective communications, within large multifacility institutions or globally with the unlimited reach of the Internet. The aim of this project was to demonstrate the implementation of a low-cost hardware and software setup that facilitates global data collaboration using WebEx and GoToMeeting Internet protocol-based videoconferencing software. Both products' features were tested and evaluated for feasibility across 2 different Internet networks, including a video quality and recording assessment. Cross-compatibility with an Apple OS is also noted in the evaluations. Departmental experiences with WebEx pertaining to clinical trials are also described. Real-time remote presentation of dynamic data was generally consistent across platforms. A reliable and inexpensive hardware and software setup for complete Internet-based data collaboration/videoconferencing can be achieved.

Rapid characterizing of ferromagnetic materials using spin rectification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Xiaolong, E-mail: fanxiaolong@lzu.edu.cn; Wang, Wei; Wang, Yutian

2014-12-29

Spin rectification is a powerful tool for dc electric detections of spin dynamics and electromagnetic waves. Technically, elaborately designed on-chip microwave devices are needed in order to realize that effect. In this letter, we propose a rapid characterizing approach based on spin rectification. By directly sending dynamic current into ferromagnetic films with stripe shape, resonant dc voltages can be detected along the longitudinal or transversal directions. As an example, Fe (010) films with precise crystalline structure and magnetic parameters were used to testify the reliability of such method. We investigated not only the dynamic parameters and the precise anisotropy constantsmore » of the Fe crystals but also the principle of spin rectification in this method.« less

Climate variation drives dengue dynamics

PubMed Central

Xu, Lei; Stige, Leif C.; Chan, Kung-Sik; Zhou, Jie; Yang, Jun; Sang, Shaowei; Wang, Ming; Yang, Zhicong; Yan, Ziqiang; Jiang, Tong; Lu, Liang; Yue, Yujuan; Liu, Xiaobo; Lin, Hualiang; Xu, Jianguo; Liu, Qiyong; Stenseth, Nils Chr.

2017-01-01

Dengue, a viral infection transmitted between people by mosquitoes, is one of the most rapidly spreading diseases in the world. Here, we report the analyses covering 11 y (2005–2015) from the city of Guangzhou in southern China. Using the first 8 y of data to develop an ecologically based model for the dengue system, we reliably predict the following 3 y of dengue dynamics—years with exceptionally extensive dengue outbreaks. We demonstrate that climate conditions, through the effects of rainfall and temperature on mosquito abundance and dengue transmission rate, play key roles in explaining the temporal dynamics of dengue incidence in the human population. Our study thus contributes to a better understanding of dengue dynamics and provides a predictive tool for preventive dengue reduction strategies. PMID:27940911

Dramatic effect of single-base mutation on the conformational dynamics of human telomeric G-quadruplex

PubMed Central

Lee, Ja Yil; Kim, D. S.

2009-01-01

Guanine-rich DNA sequences can form G-quadruplexes. These four-stranded structures are known to form in several genomic regions and to influence certain biological activities. Sometimes, the instability of G-quadruplexes causes the abnormal biological processes. Mutation is a culprit for the destabilization of G-quadruplexes, but the details of mutated G-quadruplexes are poorly understood. In this article, we investigated the conformational dynamics of single-base mutated human telomeric G-quadruplexes in the presence of K+ with single-molecule FRET spectroscopy. We observed that the replacement of single guanine by thymine in a G-track induces various folded structures, i.e. structural polymorphism. Moreover, direct observation of their dynamics revealed that a single-base mutation causes fast unfolding of folded states under physiological conditions. Furthermore, we found that the degree of destabilization varies according to mutation positions. When the central guanine of a G-track is replaced, the G-quadruplexes unfold quickly at any K+ concentrations and temperature. Meanwhile, outer-quartet mutated G-quadruplexes have heterogeneous dynamics at intermediate K+ concentrations and longstanding folded states at high K+ concentrations. Several factors such as base-stacking interaction and K+ coordination are responsible for the different dynamics according to the mutation position. PMID:19359361

Real-Time GNSS-Based Attitude Determination in the Measurement Domain

PubMed Central

Zhao, Lin; Li, Na; Li, Liang; Zhang, Yi; Cheng, Chun

2017-01-01

A multi-antenna-based GNSS receiver is capable of providing high-precision and drift-free attitude solution. Carrier phase measurements need be utilized to achieve high-precision attitude. The traditional attitude determination methods in the measurement domain and the position domain resolve the attitude and the ambiguity sequentially. The redundant measurements from multiple baselines have not been fully utilized to enhance the reliability of attitude determination. A multi-baseline-based attitude determination method in the measurement domain is proposed to estimate the attitude parameters and the ambiguity simultaneously. Meanwhile, the redundancy of attitude resolution has also been increased so that the reliability of ambiguity resolution and attitude determination can be enhanced. Moreover, in order to further improve the reliability of attitude determination, we propose a partial ambiguity resolution method based on the proposed attitude determination model. The static and kinematic experiments were conducted to verify the performance of the proposed method. When compared with the traditional attitude determination methods, the static experimental results show that the proposed method can improve the accuracy by at least 0.03° and enhance the continuity by 18%, at most. The kinematic result has shown that the proposed method can obtain an optimal balance between accuracy and reliability performance. PMID:28165434

Precise time dissemination and applications development on the Bonneville Power Administration system

NASA Technical Reports Server (NTRS)

Martin, Ken E.; Esztergalyos, J.

1992-01-01

The Bonneville Power Administration (BPA) uses IRIG-B transmitted over microwave as its primary system time dissemination. Problems with accuracy and reliability have led to ongoing research into better methods. BPA has also developed and deployed a unique fault locator which uses precise clocks synchronized by a pulse over microwaves. It automatically transmits the data to a central computer for analysis. A proposed system could combine fault location timing and time dissemination into a Global Position System (GPS) timing receiver and close the verification loop through a master station at the Dittmer Control Center. Such a system would have many advantages, including lower cost, higher reliability, and wider industry support. Test results indicate the GPS has sufficient accuracy and reliability for this and other current timing requirements including synchronous phase angle measurements. A phasor measurement system which provides phase angle has recently been tested with excellent results. Phase angle is a key parameter in power system control applications including dynamic braking, DC modulation, remedial action schemes, and system state estimation. Further research is required to determine the applications which can most effectively use real-time phase angle measurements and the best method to apply them.

Precise time dissemination and applications development on the Bonneville Power Administration system

NASA Astrophysics Data System (ADS)

Martin, Ken E.; Esztergalyos, J.

1992-07-01

The Bonneville Power Administration (BPA) uses IRIG-B transmitted over microwave as its primary system time dissemination. Problems with accuracy and reliability have led to ongoing research into better methods. BPA has also developed and deployed a unique fault locator which uses precise clocks synchronized by a pulse over microwaves. It automatically transmits the data to a central computer for analysis. A proposed system could combine fault location timing and time dissemination into a Global Position System (GPS) timing receiver and close the verification loop through a master station at the Dittmer Control Center. Such a system would have many advantages, including lower cost, higher reliability, and wider industry support. Test results indicate the GPS has sufficient accuracy and reliability for this and other current timing requirements including synchronous phase angle measurements. A phasor measurement system which provides phase angle has recently been tested with excellent results. Phase angle is a key parameter in power system control applications including dynamic braking, DC modulation, remedial action schemes, and system state estimation. Further research is required to determine the applications which can most effectively use real-time phase angle measurements and the best method to apply them.

A Terrestrial Reference Frame realised on the observation level using a GPS-LEO satellite constellation

NASA Astrophysics Data System (ADS)

Koenig, Daniel

2018-02-01

Applying a one-step integrated process, i.e. by simultaneously processing all data and determining all satellite orbits involved, a Terrestrial Reference Frame (TRF) consisting of a geometric as well as a dynamic part has been determined at the observation level using the EPOS-OC software of Deutsches GeoForschungsZentrum. The satellite systems involved comprise the Global Positioning System (GPS) as well as the twin GRACE spacecrafts. Applying a novel approach, the inherent datum defect has been overcome empirically. In order not to rely on theoretical assumptions this is done by carrying out the TRF estimation based on simulated observations and using the associated satellite orbits as background truth. The datum defect is identified here as the total of all three translations as well as the rotation about the z-axis of the ground station network leading to a rank-deficient estimation problem. To rectify this singularity, datum constraints comprising no-net translation (NNT) conditions in x, y, and z as well as a no-net rotation (NNR) condition about the z-axis are imposed. Thus minimally constrained, the TRF solution covers a time span of roughly a year with daily resolution. For the geometric part the focus is put on Helmert transformations between the a priori and the estimated sets of ground station positions, and the dynamic part is represented by gravity field coefficients of degree one and two. The results of a reference solution reveal the TRF parameters to be estimated reliably with high precision. Moreover, carrying out a comparable two-step approach using the same data and models leads to parameters and observational residuals of worse quality. A validation w.r.t. external sources shows the dynamic origin to coincide at a level of 5 mm or better in x and y, and mostly better than 15 mm in z. Comparing the derived GPS orbits to IGS final orbits as well as analysing the SLR residuals for the GRACE satellites reveals an orbit quality on the few cm level. Additional TRF test solutions demonstrate that K-Band Range-Rate observations between both GRACE spacecrafts are crucial for accurately estimating the dynamic frame's orientation, and reveal the importance of the NNT- and NNR-conditions imposed for estimating the components of the dynamic geocenter.

Fragment-Based Drug Discovery Using NMR Spectroscopy

PubMed Central

Harner, Mary J.; Frank, Andreas O.; Fesik, Stephen W.

2013-01-01

Nuclear magnetic resonance (NMR) spectroscopy has evolved into a powerful tool for fragment-based drug discovery over the last two decades. While NMR has been traditionally used to elucidate the three-dimensional structures and dynamics of biomacromolecules and their interactions, it can also be a very valuable tool for the reliable identification of small molecules that bind to proteins and for hit-to-lead optimization. Here, we describe the use of NMR spectroscopy as a method for fragment-based drug discovery and how to most effectively utilize this approach for discovering novel therapeutics based on our experience. PMID:23686385

Determination of dynamic variations in the optical properties of graphene oxide in response to gas exposure based on thin-film interference.

PubMed

Tabassum, Shawana; Dong, Liang; Kumar, Ratnesh

2018-03-05

We present an effective yet simple approach to study the dynamic variations in optical properties (such as the refractive index (RI)) of graphene oxide (GO) when exposed to gases in the visible spectral region, using the thin-film interference method. The dynamic variations in the complex refractive index of GO in response to exposure to a gas is an important factor affecting the performance of GO-based gas sensors. In contrast to the conventional ellipsometry, this method alleviates the need of selecting a dispersion model from among a list of model choices, which is limiting if an applicable model is not known a priori. In addition, the method used is computationally simpler, and does not need to employ any functional approximations. Further advantage over ellipsometry is that no bulky optics is required, and as a result it can be easily integrated into the sensing system, thereby allowing the reliable, simple, and dynamic evaluation of the optical performance of any GO-based gas sensor. In addition, the derived values of the dynamically changing RI values of the GO layer obtained from the method we have employed are corroborated by comparing with the values obtained from ellipsometry.

Efficacy of direct Gram stain in differentiating staphylococci from streptococci in blood cultures positive for gram-positive cocci.

PubMed Central

Agger, W A; Maki, D G

1978-01-01

A preponderance of clusters seen on direct Gram stain of blood cultures positive for gram-positive cocci was 98% sensitive and 100% specific for identification of staphylococcal species or of Peptococcus. A preponderance of chains, pairs, or both was 100% sensitive and 98% specific for identifying streptococci. Further presumptive identification of either staphylococci or streptococci based on microscopic morphology was unreliable. The direct Gram stain is highly reliable for differentiating staphylococci from streptococci and should be of considerable value to clinicians selecting initial antimicrobial therapy. PMID:75888

A computer simulated phantom study of tomotherapy dose optimization based on probability density functions (PDF) and potential errors caused by low reproducibility of PDF.

PubMed

Sheng, Ke; Cai, Jing; Brookeman, James; Molloy, Janelle; Christopher, John; Read, Paul

2006-09-01

Lung tumor motion trajectories measured by four-dimensional CT or dynamic MRI can be converted to a probability density function (PDF), which describes the probability of the tumor at a certain position, for PDF based treatment planning. Using this method in simulated sequential tomotherapy, we study the dose reduction of normal tissues and more important, the effect of PDF reproducibility on the accuracy of dosimetry. For these purposes, realistic PDFs were obtained from two dynamic MRI scans of a healthy volunteer within a 2 week interval. The first PDF was accumulated from a 300 s scan and the second PDF was calculated from variable scan times from 5 s (one breathing cycle) to 300 s. Optimized beam fluences based on the second PDF were delivered to the hypothetical gross target volume (GTV) of a lung phantom that moved following the first PDF The reproducibility between two PDFs varied from low (78%) to high (94.8%) when the second scan time increased from 5 s to 300 s. When a highly reproducible PDF was used in optimization, the dose coverage of GTV was maintained; phantom lung receiving 10%-20% prescription dose was reduced by 40%-50% and the mean phantom lung dose was reduced by 9.6%. However, optimization based on PDF with low reproducibility resulted in a 50% underdosed GTV. The dosimetric error increased nearly exponentially as the PDF error increased. Therefore, although the dose of the tumor surrounding tissue can be theoretically reduced by PDF based treatment planning, the reliability and applicability of this method highly depend on if a reproducible PDF exists and is measurable. By correlating the dosimetric error and PDF error together, a useful guideline for PDF data acquisition and patient qualification for PDF based planning can be derived.

A computer simulated phantom study of tomotherapy dose optimization based on probability density functions (PDF) and potential errors caused by low reproducibility of PDF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheng, Ke; Cai Jing; Brookeman, James

2006-09-15

Lung tumor motion trajectories measured by four-dimensional CT or dynamic MRI can be converted to a probability density function (PDF), which describes the probability of the tumor at a certain position, for PDF based treatment planning. Using this method in simulated sequential tomotherapy, we study the dose reduction of normal tissues and more important, the effect of PDF reproducibility on the accuracy of dosimetry. For these purposes, realistic PDFs were obtained from two dynamic MRI scans of a healthy volunteer within a 2 week interval. The first PDF was accumulated from a 300 s scan and the second PDF wasmore » calculated from variable scan times from 5 s (one breathing cycle) to 300 s. Optimized beam fluences based on the second PDF were delivered to the hypothetical gross target volume (GTV) of a lung phantom that moved following the first PDF. The reproducibility between two PDFs varied from low (78%) to high (94.8%) when the second scan time increased from 5 s to 300 s. When a highly reproducible PDF was used in optimization, the dose coverage of GTV was maintained; phantom lung receiving 10%-20% prescription dose was reduced by 40%-50% and the mean phantom lung dose was reduced by 9.6%. However, optimization based on PDF with low reproducibility resulted in a 50% underdosed GTV. The dosimetric error increased nearly exponentially as the PDF error increased. Therefore, although the dose of the tumor surrounding tissue can be theoretically reduced by PDF based treatment planning, the reliability and applicability of this method highly depend on if a reproducible PDF exists and is measurable. By correlating the dosimetric error and PDF error together, a useful guideline for PDF data acquisition and patient qualification for PDF based planning can be derived.« less

Design of a Parachute Canopy Instrumentation Platform

NASA Technical Reports Server (NTRS)

Alshahin, Wahab M.; Daum, Jared S.; Holley, James J.; Litteken, Douglas A.; Vandewalle, Michael T.

2015-01-01

This paper discusses the current technology available to design and develop a reliable and compact instrumentation platform for parachute system data collection and command actuation. Wireless communication with a parachute canopy will be an advancement to the state of the art of parachute design, development, and testing. Embedded instrumentation of the parachute canopy will provide reefing line tension, skirt position data, parachute health monitoring, and other telemetry, further validating computer models and giving engineering insight into parachute dynamics for both Earth and Mars entry that is currently unavailable. This will allow for more robust designs which are more optimally designed in terms of structural loading, less susceptible to adverse dynamics, and may eventually pave the way to currently unattainable advanced concepts of operations. The development of this technology has dual use potential for a variety of other applications including inflatable habitats, aerodynamic decelerators, heat shields, and other high stress environments.

Explosive vessel for coupling dynamic experiments to the X-ray beam at the Advanced Photon Source

NASA Astrophysics Data System (ADS)

Owens, Charles; Sanchez, Nathaniel; Sorensen, Christian; Jensen, Brian

2017-06-01

Recent experiments at the Advanced Photon Source have been successful in coupling gun systems to the synchrotron to take advantage of the advanced X-ray diagnostics available including X-ray diffraction and X-ray phase contrast imaging (PCI) to examine matter at extreme conditions. There are many experiments that require explosive loading capabilities, e.g. detonator and initiator dynamics, small angle X-ray scattering (SAXS), ejecta formation, and explosively driven flyer experiments. The current work highlights a new explosive vessel that was designed specifically for use at a synchrotron facility with requirements to confine up to 15 grams of explosives (TNT equivalent), couple the vessel to the X-ray beam line, and reliably position samples remotely. A description of the system and capability will be provided along with the results from qualification testing to bring the system into service (LA-UR-17-21381).

Optimization analysis of thermal management system for electric vehicle battery pack

NASA Astrophysics Data System (ADS)

Gong, Huiqi; Zheng, Minxin; Jin, Peng; Feng, Dong

2018-04-01

Electric vehicle battery pack can increase the temperature to affect the power battery system cycle life, charge-ability, power, energy, security and reliability. The Computational Fluid Dynamics simulation and experiment of the charging and discharging process of the battery pack were carried out for the thermal management system of the battery pack under the continuous charging of the battery. The simulation result and the experimental data were used to verify the rationality of the Computational Fluid Dynamics calculation model. In view of the large temperature difference of the battery module in high temperature environment, three optimization methods of the existing thermal management system of the battery pack were put forward: adjusting the installation position of the fan, optimizing the arrangement of the battery pack and reducing the fan opening temperature threshold. The feasibility of the optimization method is proved by simulation and experiment of the thermal management system of the optimized battery pack.

Optimal Control Method of Robot End Position and Orientation Based on Dynamic Tracking Measurement

NASA Astrophysics Data System (ADS)

Liu, Dalong; Xu, Lijuan

2018-01-01

In order to improve the accuracy of robot pose positioning and control, this paper proposed a dynamic tracking measurement robot pose optimization control method based on the actual measurement of D-H parameters of the robot, the parameters is taken with feedback compensation of the robot, according to the geometrical parameters obtained by robot pose tracking measurement, improved multi sensor information fusion the extended Kalan filter method, with continuous self-optimal regression, using the geometric relationship between joint axes for kinematic parameters in the model, link model parameters obtained can timely feedback to the robot, the implementation of parameter correction and compensation, finally we can get the optimal attitude angle, realize the robot pose optimization control experiments were performed. 6R dynamic tracking control of robot joint robot with independent research and development is taken as experimental subject, the simulation results show that the control method improves robot positioning accuracy, and it has the advantages of versatility, simplicity, ease of operation and so on.

Study of self-compliance behaviors and internal filament characteristics in intrinsic SiO{sub x}-based resistive switching memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Yao-Feng, E-mail: yfchang@utexas.edu; Zhou, Fei; Chen, Ying-Chen

2016-01-18

Self-compliance characteristics and reliability optimization are investigated in intrinsic unipolar silicon oxide (SiO{sub x})-based resistive switching (RS) memory using TiW/SiO{sub x}/TiW device structures. The program window (difference between SET voltage and RESET voltage) is dependent on external series resistance, demonstrating that the SET process is due to a voltage-triggered mechanism. The program window has been optimized for program/erase disturbance immunity and reliability for circuit-level applications. The SET and RESET transitions have also been characterized using a dynamic conductivity method, which distinguishes the self-compliance behavior due to an internal series resistance effect (filament) in SiO{sub x}-based RS memory. By using amore » conceptual “filament/resistive gap (GAP)” model of the conductive filament and a proton exchange model with appropriate assumptions, the internal filament resistance and GAP resistance can be estimated for high- and low-resistance states (HRS and LRS), and are found to be independent of external series resistance. Our experimental results not only provide insights into potential reliability issues but also help to clarify the switching mechanisms and device operating characteristics of SiO{sub x}-based RS memory.« less

The Effects of an 8-Week Stabilization Exercise Program on Lumbar Multifidus Muscle Thickness and Activation as Measured With Ultrasound Imaging in Patients With Low Back Pain: An Exploratory Study.

PubMed

Larivière, Christian; Gagnon, Dany H; Henry, Sharon M; Preuss, Richard; Dumas, Jean-Pierre

2018-05-01

Lumbar stabilization exercise programs (LSEP) produce positive effects on clinical outcomes, but the underlying mechanisms remain relatively unexplored. Psychological and neuromuscular mechanisms can be involved, such as a better activation of the lumbar multifidus, which represents one possibility. To determine the following: (1) the effect of an LSEP on lumbar multifidus muscle thickness and activation, as measured with rehabilitative ultrasound imaging (RUSI), in patients with low back pain (LBP); (2) the correlation between RUSI measures and any change in clinical outcomes following the LSEP; and (3) the reliability of RUSI measures in control subjects over 8 weeks. One-arm clinical trial with healthy subjects as a control group; reliability study. LSEP delivered in a clinical setting; outcomes measured in a laboratory setting. A total of 34 patients with nonacute LBP and 28 healthy control subjects. Outcomes were measured before and after an 8-week LSEP in patients with LBP, and at the same time interval (without treatment, to assess reliability) in control subjects. Pain numeric rating scale, Oswestry Disability Index (function), as well as RUSI measures for the lumbar multifidus (LM) muscles at 3 vertebral levels (L5-S1, L4-5, and L3-4) during rest (static) and dynamic contractions (percent thickness change). Patients did not show systematic changes in RUSI measures relative to controls, even though RUSI impairments were observed at baseline (dynamic measure at L5-S1) and even though patients had significant improvements in pain and disability. Correlational analyses with these clinical outcomes suggested that patients had reduced muscle thickness at baseline that was associated with a greater reduction in disability following LSEP; however, LM activation measured at baseline showed the opposite. Static RUSI measures showed excellent reliability at the L4-5 and L3-4 levels, whereas dynamic measures were not reliable. Patients showed less muscle activation than controls at baseline (L5-S1 level), but the LSEP did not normalize this impairment. The links between RUSI measures and the change in clinical outcomes during LSEP should be further explored. This clinical trial has been recorded in the International Standard Registered Clinical/soCial sTudy Number (ISRCTN) registry (ID: ISRCTN94152969). II. Copyright © 2018 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Reliability of Corneal Dynamic Scheimpflug Analyser Measurements in Virgin and Post-PRK Eyes

PubMed Central

Chen, Xiangjun; Stojanovic, Aleksandar; Hua, Yanjun; Eidet, Jon Roger; Hu, Di; Wang, Jingting; Utheim, Tor Paaske

2014-01-01

Purpose To determine the measurement reliability of CorVis ST, a dynamic Scheimpflug analyser, in virgin and post-photorefractive keratectomy (PRK) eyes and compare the results between these two groups. Methods Forty virgin eyes and 42 post-PRK eyes underwent CorVis ST measurements performed by two technicians. Repeatability was evaluated by comparing three consecutive measurements by technician A. Reproducibility was determined by comparing the first measurement by technician A with one performed by technician B. Intraobserver and interobserver intraclass correlation coefficients (ICCs) were calculated. Univariate analysis of covariance (ANCOVA) was used to compare measured parameters between virgin and post-PRK eyes. Results The intraocular pressure (IOP), central corneal thickness (CCT) and 1st applanation time demonstrated good intraobserver repeatability and interobserver reproducibility (ICC≧0.90) in virgin and post-PRK eyes. The deformation amplitude showed a good or close to good repeatability and reproducibility in both groups (ICC≧0.88). The CCT correlated positively with 1st applanation time (r = 0.437 and 0.483, respectively, p<0.05) and negatively with deformation amplitude (r = −0.384 and −0.375, respectively, p<0.05) in both groups. Compared to post-PRK eyes, virgin eyes showed longer 1st applanation time (7.29±0.21 vs. 6.96±0.17 ms, p<0.05) and lower deformation amplitude (1.06±0.07 vs. 1.17±0.08 mm, p<0.05). Conclusions CorVis ST demonstrated reliable measurements for CCT, IOP, and 1st applanation time, as well as relatively reliable measurement for deformation amplitude in both virgin and post-PRK eyes. There were differences in 1st applanation time and deformation amplitude between virgin and post-PRK eyes, which may reflect corneal biomechanical changes occurring after the surgery in the latter. PMID:25302580

Charge movement in a GaN-based hetero-structure field effect transistor structure with carbon doped buffer under applied substrate bias

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pooth, Alexander, E-mail: a.pooth@bristol.ac.uk; IQE; Uren, Michael J.

2015-12-07

Charge trapping and transport in the carbon doped GaN buffer of a GaN-based hetero-structure field effect transistor (HFET) has been investigated under both positive and negative substrate bias. Clear evidence of redistribution of charges in the carbon doped region by thermally generated holes is seen, with electron injection and capture observed during positive bias. Excellent agreement is found with simulations. It is shown that these effects are intrinsic to the carbon doped GaN and need to be controlled to provide reliable and efficient GaN-based power HFETs.

Unsupervised Indoor Localization Based on Smartphone Sensors, iBeacon and Wi-Fi.

PubMed

Chen, Jing; Zhang, Yi; Xue, Wei

2018-04-28

In this paper, we propose UILoc, an unsupervised indoor localization scheme that uses a combination of smartphone sensors, iBeacons and Wi-Fi fingerprints for reliable and accurate indoor localization with zero labor cost. Firstly, compared with the fingerprint-based method, the UILoc system can build a fingerprint database automatically without any site survey and the database will be applied in the fingerprint localization algorithm. Secondly, since the initial position is vital to the system, UILoc will provide the basic location estimation through the pedestrian dead reckoning (PDR) method. To provide accurate initial localization, this paper proposes an initial localization module, a weighted fusion algorithm combined with a k-nearest neighbors (KNN) algorithm and a least squares algorithm. In UILoc, we have also designed a reliable model to reduce the landmark correction error. Experimental results show that the UILoc can provide accurate positioning, the average localization error is about 1.1 m in the steady state, and the maximum error is 2.77 m.

Measurement and inference of profile soil-water dynamics at different hillslope positions in a semiarid agricultural watershed

NASA Astrophysics Data System (ADS)

Green, Timothy R.; Erskine, Robert H.

2011-12-01

Dynamics of profile soil water vary with terrain, soil, and plant characteristics. The objectives addressed here are to quantify dynamic soil water content over a range of slope positions, infer soil profile water fluxes, and identify locations most likely influenced by multidimensional flow. The instrumented 56 ha watershed lies mostly within a dryland (rainfed) wheat field in semiarid eastern Colorado. Dielectric capacitance sensors were used to infer hourly soil water content for approximately 8 years (minus missing data) at 18 hillslope positions and four or more depths. Based on previous research and a new algorithm, sensor measurements (resonant frequency) were rescaled to estimate soil permittivity, then corrected for temperature effects on bulk electrical conductivity before inferring soil water content. Using a mass-conservation method, we analyzed multitemporal changes in soil water content at each sensor to infer the dynamics of water flux at different depths and landscape positions. At summit positions vertical processes appear to control profile soil water dynamics. At downslope positions infrequent overland flow and unsaturated subsurface lateral flow appear to influence soil water dynamics. Crop water use accounts for much of the variability in soil water between transects that are either cropped or fallow in alternating years, while soil hydraulic properties and near-surface hydrology affect soil water variability across landscape positions within each management zone. The observed spatiotemporal patterns exhibit the joint effects of short-term hydrology and long-term soil development. Quantitative methods of analyzing soil water patterns in space and time improve our understanding of dominant soil hydrological processes and provide alternative measures of model performance.

Development and Exemplification of a Model for Teacher Assessment in Primary Science

ERIC Educational Resources Information Center

Davies, D. J.; Earle, S.; McMahon, K.; Howe, A.; Collier, C.

2017-01-01

The Teacher Assessment in Primary Science project is funded by the Primary Science Teaching Trust and based at Bath Spa University. The study aims to develop a whole-school model of valid, reliable and manageable teacher assessment to inform practice and make a positive impact on primary-aged children's learning in science. The model is based on a…

Positive Association of Child Involvement and Treatment Outcome within a Manual-Based Cognitive-Behavioral Treatment for Children with Anxiety

ERIC Educational Resources Information Center

Chu, Brian C.; Kendall, Philip C.

2004-01-01

Ratings of child involvement in manual-based cognitive-behavioral treatment for anxiety were associated with the absence of primary anxiety diagnosis and reductions in impairment ratings at posttreatment for 59 children with anxiety (ages 8-14 years). Good-to-excellent interrater reliability was established for the independent ratings of 237…

Diminished neural network dynamics after moderate and severe traumatic brain injury.

PubMed

Gilbert, Nicholas; Bernier, Rachel A; Calhoun, Vincent D; Brenner, Einat; Grossner, Emily; Rajtmajer, Sarah M; Hillary, Frank G

2018-01-01

Over the past decade there has been increasing enthusiasm in the cognitive neurosciences around using network science to understand the system-level changes associated with brain disorders. A growing literature has used whole-brain fMRI analysis to examine changes in the brain's subnetworks following traumatic brain injury (TBI). Much of network modeling in this literature has focused on static network mapping, which provides a window into gross inter-nodal relationships, but is insensitive to more subtle fluctuations in network dynamics, which may be an important predictor of neural network plasticity. In this study, we examine the dynamic connectivity with focus on state-level connectivity (state) and evaluate the reliability of dynamic network states over the course of two runs of intermittent task and resting data. The goal was to examine the dynamic properties of neural networks engaged periodically with task stimulation in order to determine: 1) the reliability of inter-nodal and network-level characteristics over time and 2) the transitions between distinct network states after traumatic brain injury. To do so, we enrolled 23 individuals with moderate and severe TBI at least 1-year post injury and 19 age- and education-matched healthy adults using functional MRI methods, dynamic connectivity modeling, and graph theory. The results reveal several distinct network "states" that were reliably evident when comparing runs; the overall frequency of dynamic network states are highly reproducible (r-values>0.8) for both samples. Analysis of movement between states resulted in fewer state transitions in the TBI sample and, in a few cases, brain injury resulted in the appearance of states not exhibited by the healthy control (HC) sample. Overall, the findings presented here demonstrate the reliability of observable dynamic mental states during periods of on-task performance and support emerging evidence that brain injury may result in diminished network dynamics.

Diminished neural network dynamics after moderate and severe traumatic brain injury

PubMed Central

Gilbert, Nicholas; Bernier, Rachel A.; Calhoun, Vincent D.; Brenner, Einat; Grossner, Emily; Rajtmajer, Sarah M.

2018-01-01

Over the past decade there has been increasing enthusiasm in the cognitive neurosciences around using network science to understand the system-level changes associated with brain disorders. A growing literature has used whole-brain fMRI analysis to examine changes in the brain’s subnetworks following traumatic brain injury (TBI). Much of network modeling in this literature has focused on static network mapping, which provides a window into gross inter-nodal relationships, but is insensitive to more subtle fluctuations in network dynamics, which may be an important predictor of neural network plasticity. In this study, we examine the dynamic connectivity with focus on state-level connectivity (state) and evaluate the reliability of dynamic network states over the course of two runs of intermittent task and resting data. The goal was to examine the dynamic properties of neural networks engaged periodically with task stimulation in order to determine: 1) the reliability of inter-nodal and network-level characteristics over time and 2) the transitions between distinct network states after traumatic brain injury. To do so, we enrolled 23 individuals with moderate and severe TBI at least 1-year post injury and 19 age- and education-matched healthy adults using functional MRI methods, dynamic connectivity modeling, and graph theory. The results reveal several distinct network “states” that were reliably evident when comparing runs; the overall frequency of dynamic network states are highly reproducible (r-values>0.8) for both samples. Analysis of movement between states resulted in fewer state transitions in the TBI sample and, in a few cases, brain injury resulted in the appearance of states not exhibited by the healthy control (HC) sample. Overall, the findings presented here demonstrate the reliability of observable dynamic mental states during periods of on-task performance and support emerging evidence that brain injury may result in diminished network dynamics. PMID:29883447

Reduction of Dynamic Loads in Mine Lifting Installations

NASA Astrophysics Data System (ADS)

Kuznetsov, N. K.; Eliseev, S. V.; Perelygina, A. Yu

2018-01-01

Article is devoted to a problem of decrease in the dynamic loadings arising in transitional operating modes of the mine lifting installations leading to heavy oscillating motions of lifting vessels and decrease in efficiency and reliability of work. The known methods and means of decrease in dynamic loadings and oscillating motions of the similar equipment are analysed. It is shown that an approach based on the concept of the inverse problems of dynamics can be effective method of the solution of this problem. The article describes the design model of a one-ended lifting installation in the form of a two-mass oscillation system, in which the inertial elements are the mass of the lifting vessel and the reduced mass of the engine, reducer, drum and pulley. The simplified mathematical model of this system and results of an efficiency research of an active way of reduction of dynamic loadings of lifting installation on the basis of the concept of the inverse problems of dynamics are given.

Potential-based dynamical reweighting for Markov state models of protein dynamics.

PubMed

Weber, Jeffrey K; Pande, Vijay S

2015-06-09

As simulators attempt to replicate the dynamics of large cellular components in silico, problems related to sampling slow, glassy degrees of freedom in molecular systems will be amplified manyfold. It is tempting to augment simulation techniques with external biases to overcome such barriers with ease; biased simulations, however, offer little utility unless equilibrium properties of interest (both kinetic and thermodynamic) can be recovered from the data generated. In this Article, we present a general scheme that harnesses the power of Markov state models (MSMs) to extract equilibrium kinetic properties from molecular dynamics trajectories collected on biased potential energy surfaces. We first validate our reweighting protocol on a simple two-well potential, and we proceed to test our method on potential-biased simulations of the Trp-cage miniprotein. In both cases, we find that equilibrium populations, time scales, and dynamical processes are reliably reproduced as compared to gold standard, unbiased data sets. We go on to discuss the limitations of our dynamical reweighting approach, and we suggest auspicious target systems for further application.

How reproducible is home-based 24-hour ambulatory monitoring of motor activity in patients with multiple sclerosis?

PubMed

Rietberg, Marc B; van Wegen, Erwin E; Uitdehaag, Bernard M; de Vet, Henrica C; Kwakkel, Gert

2010-10-01

To determine the reproducibility of 24-hour monitoring of motor activity in patients with multiple sclerosis (MS). Test-retest design; 6 research assistants visited the participants twice within 1 week in the home situation. General community. A convenience sample of ambulatory patients (N=43; mean age ± SD, 48.7±7.0y; 30 women; median Expanded Disability Status Scale scores, 3.5; interquartile range, 2.5) were recruited from the outpatient clinic of a university medical center. Not applicable. Dynamic activity and static activity parameters were recorded by using a portable data logger and classified continuously for 24 hours. Reproducibility was determined by calculating intraclass correlation coefficients (ICCs) for test-retest reliability and by applying the Bland-Altman method for agreement between the 2 measurements. The smallest detectable change (SDC) was calculated based on the standard error of measurement. Test-retest reliability expressed by the ICC(agreement) was .72 for dynamic activity, .74 for transitions, .77 for walking, .71 for static activity, .67 for sitting, .62 for standing, and .55 for lying. Bland and Altman analysis indicated no systematic differences between the first and second assessment for dynamic and static activity. Measurement error expressed by the SDC was 1.23 for dynamic activity, 66 for transitions, .99 for walking, 1.52 for static activity, 4.68 for lying, 3.95 for sitting, and 3.34 for standing. The current study shows that with 24-hour monitoring, a reproducible estimate of physical activity can be obtained in ambulatory patients with MS. Copyright © 2010 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Technologies for network-centric C4ISR

NASA Astrophysics Data System (ADS)

Dunkelberger, Kirk A.

2003-07-01

Three technologies form the heart of any network-centric command, control, communication, intelligence, surveillance, and reconnaissance (C4ISR) system: distributed processing, reconfigurable networking, and distributed resource management. Distributed processing, enabled by automated federation, mobile code, intelligent process allocation, dynamic multiprocessing groups, check pointing, and other capabilities creates a virtual peer-to-peer computing network across the force. Reconfigurable networking, consisting of content-based information exchange, dynamic ad-hoc routing, information operations (perception management) and other component technologies forms the interconnect fabric for fault tolerant inter processor and node communication. Distributed resource management, which provides the means for distributed cooperative sensor management, foe sensor utilization, opportunistic collection, symbiotic inductive/deductive reasoning and other applications provides the canonical algorithms for network-centric enterprises and warfare. This paper introduces these three core technologies and briefly discusses a sampling of their component technologies and their individual contributions to network-centric enterprises and warfare. Based on the implied requirements, two new algorithms are defined and characterized which provide critical building blocks for network centricity: distributed asynchronous auctioning and predictive dynamic source routing. The first provides a reliable, efficient, effective approach for near-optimal assignment problems; the algorithm has been demonstrated to be a viable implementation for ad-hoc command and control, object/sensor pairing, and weapon/target assignment. The second is founded on traditional dynamic source routing (from mobile ad-hoc networking), but leverages the results of ad-hoc command and control (from the contributed auctioning algorithm) into significant increases in connection reliability through forward prediction. Emphasis is placed on the advantages gained from the closed-loop interaction of the multiple technologies in the network-centric application environment.

Estimating fine-scale land use change dynamics using an expedient photointerpretation-based method

Treesearch

Tonya Lister; Andrew Lister; Eunice Alexander

2009-01-01

Population growth and urban expansion have resulted in the loss of forest land. With growing concerns about this loss and its implications for global processes and carbon budgets, there is a great need for detailed and reliable land use change data. Currently, the Northern Research Station uses an Annual Inventory design whereby all plots are revisited every 5 years...

Photopolymer based VPHGs: from materials to sky results

NASA Astrophysics Data System (ADS)

Zanutta, A.; Orselli, E.; Fäcke, T.; Bianco, A.

2016-07-01

Volume Phase Holographic Gratings cover a relevant position as transmission dispersing elements in astronomical spectrographs and each astronomical observation could take advantage of specific dispersive elements with features tailored for achieving the best performances. The design and manufacturing of high efficiency and reliable VPHGs require photosensitive materials where it is possible to control both the refractive index modulation and the film thickness. By means of Bayfol® HX photopolymers, we designed and manufactured six VPHGs for astronomical instrumentation in a GRISM configuration. We demonstrated how photopolymers are reliable holographic materials for making astronomical VPHGs with performances comparable to those provided by VPHGs based on Dichromated Gelatins (DCGs), but with a much simpler production process.

Geodetic positioning using a global positioning system of satellites

NASA Technical Reports Server (NTRS)

Fell, P. J.

1980-01-01

Geodetic positioning using range, integrated Doppler, and interferometric observations from a constellation of twenty-four Global Positioning System satellites is analyzed. A summary of the proposals for geodetic positioning and baseline determination is given which includes a description of measurement techniques and comments on rank deficiency and error sources. An analysis of variance comparison of range, Doppler, and interferometric time delay to determine their relative geometric strength for baseline determination is included. An analytic examination to the effect of a priori constraints on positioning using simultaneous observations from two stations is presented. Dynamic point positioning and baseline determination using range and Doppler is examined in detail. Models for the error sources influencing dynamic positioning are developed. Included is a discussion of atomic clock stability, and range and Doppler observation error statistics based on random correlated atomic clock error are derived.

Position Estimation for Switched Reluctance Motor Based on the Single Threshold Angle

NASA Astrophysics Data System (ADS)

Zhang, Lei; Li, Pang; Yu, Yue

2017-05-01

This paper presents a position estimate model of switched reluctance motor based on the single threshold angle. In view of the relationship of between the inductance and rotor position, the position is estimated by comparing the real-time dynamic flux linkage with the threshold angle position flux linkage (7.5° threshold angle, 12/8SRM). The sensorless model is built by Maltab/Simulink, the simulation are implemented under the steady state and transient state different condition, and verified its validity and feasibility of the method..

Rational design of methicillin resistance staphylococcus aureus inhibitors through 3D-QSAR, molecular docking and molecular dynamics simulations.

PubMed

Ballu, Srilata; Itteboina, Ramesh; Sivan, Sree Kanth; Manga, Vijjulatha

2018-04-01

Staphylococcus aureus is a gram positive bacterium. It is the leading cause of skin and respiratory infections, osteomyelitis, Ritter's disease, endocarditis, and bacteraemia in the developed world. We employed combined studies of 3D QSAR, molecular docking which are validated by molecular dynamics simulations and in silico ADME prediction have been performed on Isothiazoloquinolones inhibitors against methicillin resistance Staphylococcus aureus. Three-dimensional quantitative structure-activity relationship (3D-QSAR) study was applied using comparative molecular field analysis (CoMFA) with Q 2 of 0.578, R 2 of 0.988, and comparative molecular similarity indices analysis (CoMSIA) with Q 2 of 0.554, R 2 of 0.975. The predictive ability of these model was determined using a test set of molecules that gave acceptable predictive correlation (r 2 Pred) values 0.55 and 0.57 of CoMFA and CoMSIA respectively. Docking, simulations were employed to position the inhibitors into protein active site to find out the most probable binding mode and most reliable conformations. Developed models and Docking methods provide guidance to design molecules with enhanced activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dynamic footprint measurement collection technique and intrarater reliability: ink mat, paper pedography, and electronic pedography.

PubMed

Fascione, Jeanna M; Crews, Ryan T; Wrobel, James S

2012-01-01

Identifying the variability of footprint measurement collection techniques and the reliability of footprint measurements would assist with appropriate clinical foot posture appraisal. We sought to identify relationships between these measures in a healthy population. On 30 healthy participants, midgait dynamic footprint measurements were collected using an ink mat, paper pedography, and electronic pedography. The footprints were then digitized, and the following footprint indices were calculated with photo digital planimetry software: footprint index, arch index, truncated arch index, Chippaux-Smirak Index, and Staheli Index. Differences between techniques were identified with repeated-measures analysis of variance with post hoc test of Scheffe. In addition, to assess practical similarities between the different methods, intraclass correlation coefficients (ICCs) were calculated. To assess intrarater reliability, footprint indices were calculated twice on 10 randomly selected ink mat footprint measurements, and the ICC was calculated. Dynamic footprint measurements collected with an ink mat significantly differed from those collected with paper pedography (ICC, 0.85-0.96) and electronic pedography (ICC, 0.29-0.79), regardless of the practical similarities noted with ICC values (P = .00). Intrarater reliability for dynamic ink mat footprint measurements was high for the footprint index, arch index, truncated arch index, Chippaux-Smirak Index, and Staheli Index (ICC, 0.74-0.99). Footprint measurements collected with various techniques demonstrate differences. Interchangeable use of exact values without adjustment is not advised. Intrarater reliability of a single method (ink mat) was found to be high.

Evaluating plyometric exercises using time to stabilization.

PubMed

Ebben, William P; Vanderzanden, Tyler; Wurm, Bradley J; Petushek, Erich J

2010-02-01

Plyometric exercises are frequently used in strength and conditioning and rehabilitation programs because the landing phase of these exercises requires dynamic stabilization. This study examined the differences in landing stability of a variety of plyometric exercises by assessing time to stabilization (TTS), its reliability, and sex differences therein. Forty-nine men and women performed a variety of plyometric exercises thought to represent a continuum of difficulty of dynamic stabilization during landing. Plyometric exercises included line hops, cone hops, squat jumps, tuck jumps, countermovement jumps, dumbbell countermovement jumps, and single leg countermovement jumps, each performed for 3 repetitions on a force platform. A 2-way mixed analysis of covariance with repeated measures for plyometric exercise type was used to evaluate the main effects for plyometric exercise type and the interaction between plyometric exercise type and sex for TTS. Subject jumping ability was evaluated as a covariate. Results revealed significant main effects for plyometric exercise type (p < or = 0.001) and for the interaction between plyometric exercise type and sex (p = 0.002). Bonferroni adjusted post hoc analysis demonstrated differences in TTS between a number of plyometric exercises for men and women. Reliability analysis revealed intraclass correlation coefficients ranging from 0.51 to 0.86 with no significant difference between trials (p > 0.05). Practitioners who use plyometrics to train dynamic stability should create programs that progress the intensity of the exercises based on the results of this study. This study also demonstrated that TTS is moderately to highly reliable for a variety of jumping conditions for both men and women.

Longitudinal Models of Reliability and Validity: A Latent Curve Approach.

ERIC Educational Resources Information Center

Tisak, John; Tisak, Marie S.

1996-01-01

Dynamic generalizations of reliability and validity that will incorporate longitudinal or developmental models, using latent curve analysis, are discussed. A latent curve model formulated to depict change is incorporated into the classical definitions of reliability and validity. The approach is illustrated with sociological and psychological…

Broadband interferometric characterisation of nano-positioning stages with sub-10 pm resolution

NASA Astrophysics Data System (ADS)

Li, Zhi; Brand, Uwe; Wolff, Helmut; Koenders, Ludger; Yacoot, Andrew; Puranto, Prabowo

2017-06-01

A traceable calibration setup for investigation of the quasi-static and the dynamic performance of nano-positioning stages is detailed, which utilizes a differential plane-mirror interferometer with double-pass configuration from the National Physical Laboratory (NPL). An NPL-developed FPGA-based interferometric data acquisition and decoding system has been used to enable traceable quasi-static calibration of nano-positioning stages with high resolution. A lockin based modulation technique is further introduced to quantitatively calibrate the dynamic response of moving stages with a bandwidth up to 100 kHz and picometer resolution. First experimental results have proven that the calibration setup can achieve under nearly open-air conditions a noise floor lower than 10 pm/sqrt(Hz). A pico-positioning stage, that is used for nanoindentation with indentation depths down to a few picometers, has been characterized with this calibration setup.

Strength Analysis and Reliability Evaluation for Speed Reducers

NASA Astrophysics Data System (ADS)

Tsai, Yuo-Tern; Hsu, Yung-Yuan

2017-09-01

This paper studies the structural stresses of differential drive (DD) and harmonic drive (HD) for design improvement of reducers. The designed principles of the two reducers are reported for function comparison. The critical components of the reducers are constructed for performing motion simulation and stress analysis. DD is designed based on differential displacement of the decelerated gear ring as well as HD on a flexible spline. Finite element method (FEM) is used to analyze the structural stresses including the dynamic properties of the reducers. The stresses including kinematic properties of the two reducers are compared to observe the properties of the designs. The analyzed results are applied to identify the allowable loads of the reducers in use. The reliabilities of the reducers in different loads are further calculated according to the variation of stress. The studied results are useful on engineering analysis and reliability evaluation for designing a speed reducer with high ratios.

Identification of Extracellular Segments by Mass Spectrometry Improves Topology Prediction of Transmembrane Proteins.

PubMed

Langó, Tamás; Róna, Gergely; Hunyadi-Gulyás, Éva; Turiák, Lilla; Varga, Julia; Dobson, László; Várady, György; Drahos, László; Vértessy, Beáta G; Medzihradszky, Katalin F; Szakács, Gergely; Tusnády, Gábor E

2017-02-13

Transmembrane proteins play crucial role in signaling, ion transport, nutrient uptake, as well as in maintaining the dynamic equilibrium between the internal and external environment of cells. Despite their important biological functions and abundance, less than 2% of all determined structures are transmembrane proteins. Given the persisting technical difficulties associated with high resolution structure determination of transmembrane proteins, additional methods, including computational and experimental techniques remain vital in promoting our understanding of their topologies, 3D structures, functions and interactions. Here we report a method for the high-throughput determination of extracellular segments of transmembrane proteins based on the identification of surface labeled and biotin captured peptide fragments by LC/MS/MS. We show that reliable identification of extracellular protein segments increases the accuracy and reliability of existing topology prediction algorithms. Using the experimental topology data as constraints, our improved prediction tool provides accurate and reliable topology models for hundreds of human transmembrane proteins.

A novel unscented predictive filter for relative position and attitude estimation of satellite formation

NASA Astrophysics Data System (ADS)

Cao, Lu; Chen, Xiaoqian; Misra, Arun K.

2015-07-01

This paper presents a novel sigma-point unscented predictive filter (UPF) for relative position and attitude estimation of satellite formation taking into account the influence of J2. A coupled relative translational dynamics model is formulated to represent orbital motion of arbitrary feature points on the deputy spacecraft, and the relative attitude motion is formulated by considering a rotational dynamics for a satellite without gyros. Based on the proposed coupled dynamic model, the UPF is developed based on unscented transformation technique, extending the capability of a traditional predictive filter (PF). The algorithm flow of the UPF is described first. Then it is demonstrated that the estimation accuracy of the model error and system state for UPF is higher than that of the traditional PF. In addition, the unscented Kalman filter (UKF) is also employed in order to compare the performance of the proposed UPF with that of the UKF. Several different scenarios are simulated to validate the effectiveness of the coupled dynamics model and the performance of the proposed UPF. Through comparisons, the proposed UPF is shown to yield highly accurate estimation of relative position and attitude during satellite formation flying.

Reliability Prediction of Ontology-Based Service Compositions Using Petri Net and Time Series Models

PubMed Central

Li, Jia; Xia, Yunni; Luo, Xin

2014-01-01

OWL-S, one of the most important Semantic Web service ontologies proposed to date, provides a core ontological framework and guidelines for describing the properties and capabilities of their web services in an unambiguous, computer interpretable form. Predicting the reliability of composite service processes specified in OWL-S allows service users to decide whether the process meets the quantitative quality requirement. In this study, we consider the runtime quality of services to be fluctuating and introduce a dynamic framework to predict the runtime reliability of services specified in OWL-S, employing the Non-Markovian stochastic Petri net (NMSPN) and the time series model. The framework includes the following steps: obtaining the historical response times series of individual service components; fitting these series with a autoregressive-moving-average-model (ARMA for short) and predicting the future firing rates of service components; mapping the OWL-S process into a NMSPN model; employing the predicted firing rates as the model input of NMSPN and calculating the normal completion probability as the reliability estimate. In the case study, a comparison between the static model and our approach based on experimental data is presented and it is shown that our approach achieves higher prediction accuracy. PMID:24688429

High reliable and stable organic field-effect transistor nonvolatile memory with a poly(4-vinyl phenol) charge trapping layer based on a pn-heterojunction active layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiang, Lanyi; Ying, Jun; Han, Jinhua

2016-04-25

In this letter, we demonstrate a high reliable and stable organic field-effect transistor (OFET) based nonvolatile memory (NVM) with a polymer poly(4-vinyl phenol) (PVP) as the charge trapping layer. In the unipolar OFETs, the inreversible shifts of the turn-on voltage (V{sub on}) and severe degradation of the memory window (ΔV{sub on}) at programming (P) and erasing (E) voltages, respectively, block their application in NVMs. The obstacle is overcome by using a pn-heterojunction as the active layer in the OFET memory, which supplied a holes and electrons accumulating channel at the supplied P and E voltages, respectively. Both holes and electronsmore » transferring from the channels to PVP layer and overwriting the trapped charges with an opposite polarity result in the reliable bidirectional shifts of V{sub on} at P and E voltages, respectively. The heterojunction OFET exhibits excellent nonvolatile memory characteristics, with a large ΔV{sub on} of 8.5 V, desired reading (R) voltage at 0 V, reliable P/R/E/R dynamic endurance over 100 cycles and a long retention time over 10 years.« less

Anatomical landmark asymmetry assessment in the lumbar spine and pelvis: a review of reliability.

PubMed

Stovall, Bradley Alan; Kumar, Shrawan

2010-01-01

The purpose of this article is to review current research investigating the reliability of bony anatomical landmark positional asymmetry assessment in the lumbar spine and pelvis, to determine the agreement on findings between authors, and to explore future directions in the area to address the significant issues. The databases MEDLINE, CINAHL, AMED, MANTIS, Academic Search Complete, and Web of Knowledge were searched. A total of 23 articles were identified and reviewed, 10 of which met the inclusion criteria. For these 10 articles, the average interexaminer reliability for bony anatomical landmark positional asymmetry assessment was slightly above chance for all landmarks except medial malleolus, which had fair reliability. Interexaminer reliability on average was less than intraexaminer reliability (anterior superior iliac spine, k = 0.128/0.414; posterior superior iliac spine, k = 0.092/0.371). All interexaminer reliability averages were below values of clinical significance. From the current literature review, bony anatomical landmark positional asymmetry assessment in the lumbar spine and pelvis has not been demonstrated to be a reliable assessment method. However, there are unexplored factors that, after standardization, may improve reliability and further the understanding of musculoskeletal palpatory examination.

Flow measurements in sewers based on image analysis: automatic flow velocity algorithm.

PubMed

Jeanbourquin, D; Sage, D; Nguyen, L; Schaeli, B; Kayal, S; Barry, D A; Rossi, L

2011-01-01

Discharges of combined sewer overflows (CSOs) and stormwater are recognized as an important source of environmental contamination. However, the harsh sewer environment and particular hydraulic conditions during rain events reduce the reliability of traditional flow measurement probes. An in situ system for sewer water flow monitoring based on video images was evaluated. Algorithms to determine water velocities were developed based on image-processing techniques. The image-based water velocity algorithm identifies surface features and measures their positions with respect to real world coordinates. A web-based user interface and a three-tier system architecture enable remote configuration of the cameras and the image-processing algorithms in order to calculate automatically flow velocity on-line. Results of investigations conducted in a CSO are presented. The system was found to measure reliably water velocities, thereby providing the means to understand particular hydraulic behaviors.

Rational design and validation of an anti-protein kinase C active-state specific antibody based on conformational changes.

PubMed

Pena, Darlene Aparecida; Andrade, Victor Piana de; Silva, Gabriela Ávila Fernandes; Neves, José Ivanildo; Oliveira, Paulo Sergio Lopes de; Alves, Maria Julia Manso; Devi, Lakshmi A; Schechtman, Deborah

2016-02-25

Protein kinase C (PKC) plays a regulatory role in key pathways in cancer. However, since phosphorylation is a step for classical PKC (cPKC) maturation and does not correlate with activation, there is a lack of tools to detect active PKC in tissue samples. Here, a structure-based rational approach was used to select a peptide to generate an antibody that distinguishes active from inactive cPKC. A peptide conserved in all cPKCs, C2Cat, was chosen since modeling studies based on a crystal structure of PKCβ showed that it is localized at the interface between the C2 and catalytic domains of cPKCs in an inactive kinase. Anti-C2Cat recognizes active cPKCs at least two-fold better than inactive kinase in ELISA and immunoprecipitation assays, and detects the temporal dynamics of cPKC activation upon receptor or phorbol stimulation. Furthermore, the antibody is able to detect active PKC in human tissue. Higher levels of active cPKC were observed in the more aggressive triple negative breast cancer tumors as compared to the less aggressive estrogen receptor positive tumors. Thus, this antibody represents a reliable, hitherto unavailable and a valuable tool to study PKC activation in cells and tissues. Similar structure-based rational design strategies can be broadly applied to obtain active-state specific antibodies for other signal transduction molecules.

Evaluation of Counter-Based Dynamic Load Balancing Schemes for Massive Contingency Analysis on Over 10,000 Cores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Yousu; Huang, Zhenyu; Rice, Mark J.

Contingency analysis studies are necessary to assess the impact of possible power system component failures. The results of the contingency analysis are used to ensure the grid reliability, and in power market operation for the feasibility test of market solutions. Currently, these studies are performed in real time based on the current operating conditions of the grid with a set of pre-selected contingency list, which might result in overlooking some critical contingencies caused by variable system status. To have a complete picture of a power grid, more contingencies need to be studied to improve grid reliability. High-performance computing techniques holdmore » the promise of being able to perform the analysis for more contingency cases within a much shorter time frame. This paper evaluates the performance of counter-based dynamic load balancing schemes for a massive contingency analysis program on 10,000+ cores. One million N-2 contingency analysis cases with a Western Electricity Coordinating Council power grid model have been used to demonstrate the performance. The speedup of 3964 with 4096 cores and 7877 with 10240 cores are obtained. This paper reports the performance of the load balancing scheme with a single counter and two counters, describes disk I/O issues, and discusses other potential techniques for further improving the performance.« less

Inter-Operator Dependence of Magnetic Resonance Image-Based Computational Fluid Dynamics Prediction of Cerebrospinal Fluid Motion in the Cervical Spine

PubMed Central

Martin, Bryn A.; Yiallourou, Theresia I.; Pahlavian, Soroush Heidari; Thyagaraj, Suraj; Bunck, Alexander C.; Loth, Francis; Sheffer, Daniel B.; Kröger, Jan Robert; Stergiopulos, Nikolaos

2015-01-01

For the first time, inter-operator dependence of MRI based computational fluid dynamics (CFD) modeling of cerebrospinal fluid (CSF) in the cervical spinal subarachnoid space (SSS) is evaluated. In vivo MRI flow measurements and anatomy MRI images were obtained at the cervico-medullary junction of a healthy subject and a Chiari I malformation patient. 3D anatomies of the SSS were reconstructed by manual segmentation by four independent operators for both cases. CFD results were compared at nine axial locations along the SSS in terms of hydrodynamic and geometric parameters. Intraclass correlation (ICC) assessed the inter-operator agreement for each parameter over the axial locations and coefficient of variance (CV) compared the percentage of variance for each parameter between the operators. Greater operator dependence was found for the patient (0.19 0.78). For the healthy subject, hydraulic diameter and Womersley number had the least variance (CV= ~2%). For the patient, peak diastolic velocity and Reynolds number had the smallest variance (CV= ~3%). These results show a high degree of inter-operator reliability for MRI-based CFD simulations of CSF flow in the cervical spine for healthy subjects and a lower degree of reliability for patients with Type I Chiari malformation. PMID:26446009

Lateral motion stability of high-temperature superconducting maglev systems derived from a nonlinear guidance force hysteretic model

NASA Astrophysics Data System (ADS)

Li, Haitao; Deng, Zigang; Jin, Li’an; Li, Jipeng; Li, Yanxing; Zheng, Jun

2018-07-01

High-temperature superconducting (HTS) maglev, owning to the capability of passive stabilization, is potentially promising for high-speed transportation. The guidance force of bulk HTS materials above a permanent magnetic guideway has a nonlinear response due to the hysteresis effect. As a kind of rail transit, when the vehicle runs along the track, the curve and other disturbances will cause vibrations to the vehicle system. These physical factors will pose dynamic loads on the components, reducing structural reliability as well as affecting the ride comfort. The lateral motion, as an important part of the vehicle system dynamics, needs to be studied in the pursuit of HTS maglev realization. In this paper, we first measured the guidance forces of HTS bulks under different motion conditions, and analyzed the relationship between the lateral displacement, the movement velocity and the guidance force. Then, a mathematical model was built based on these experimental data. The key feature of this mathematical model is that it can describe the hysteresis characteristic of the guidance force. Based on this model, we investigated the lateral motion stability of the HTS levitation system, and found three singular points, one stable focus point, and two unstable saddle points. Lastly, a phase portrait was proposed to indicate the safe working region of the HTS maglev vehicle where the vehicle can automatically return to its equilibrium position. These experimental and simulation results are important to clarify the lateral motion stability under external disturbance or shock, and provide a reference basis for the design of levitation systems.

"In our stories": The perspectives of women living with HIV on an evidence-based group intervention.

PubMed

Dale, Sannisha K; Grimes, Tiffany; Miller, Lauren; Ursillo, Alyssa; Drainoni, Mari-Lynn

2017-07-01

A qualitative study among women living with HIV assessed the aspects of an evidence-based intervention targeting HIV transmission risk reduction (Women Involved in Life Learning from Other Women [WiLLOW]) that women valued and how their lives were impacted. Thirty-one women (80.6% African American) completed interviews. Women valued the personal stories and positive group dynamics (i.e. safety, trust, openness, getting feedback, bonding, and socializing). As a result of WiLLOW, women embraced a strong woman image, joined groups, changed behaviors, accepted their HIV status, became optimistic, and spoke up/advocated in their relationships and communities. Interventions for HIV-positive women may benefit from incorporating the sharing of stories in their curricula and factors that build positive group dynamics.

Robust independent modal space control of a coupled nano-positioning piezo-stage

NASA Astrophysics Data System (ADS)

Zhu, Wei; Yang, Fufeng; Rui, Xiaoting

2018-06-01

In order to accurately control a coupled 3-DOF nano-positioning piezo-stage, this paper designs a hybrid controller. In this controller, a hysteresis observer based on a Bouc-Wen model is established to compensate the hysteresis nonlinearity of the piezoelectric actuator first. Compared to hysteresis compensations using Preisach model and Prandt-Ishlinskii model, the compensation method using the hysteresis observer is computationally lighter. Then, based on the proposed dynamics model, by constructing the modal filter, a robust H∞ independent modal space controller is designed and utilized to decouple the piezo-stage and deal with the unmodeled dynamics, disturbance, and hysteresis compensation error. The effectiveness of the proposed controller is demonstrated experimentally. The experimental results show that the proposed controller can significantly achieve the high-precision positioning.

Intrarater test-retest reliability of static and dynamic stability indexes measurement using the Biodex Stability System during unilateral stance.

PubMed

Arifin, Nooranida; Abu Osman, Noor Azuan; Wan Abas, Wan Abu Bakar

2014-04-01

The measurements of postural balance often involve measurement error, which affects the analysis and interpretation of the outcomes. In most of the existing clinical rehabilitation research, the ability to produce reliable measures is a prerequisite for an accurate assessment of an intervention after a period of time. Although clinical balance assessment has been performed in previous study, none has determined the intrarater test-retest reliability of static and dynamic stability indexes during dominant single stance. In this study, one rater examined 20 healthy university students (female=12, male=8) in two sessions separated by 7 day intervals. Three stability indexes--the overall stability index (OSI), anterior/posterior stability index (APSI), and medial/ lateral stability index (MLSI) in static and dynamic conditions--were measured during single dominant stance. Intraclass correlation coefficient (ICC), standard error measurement (SEM) and 95% confidence interval (95% CI) were calculated. Test-retest ICCs for OSI, APSI, and MLSI were 0.85, 0.78, and 0.84 during static condition and were 0.77, 0.77, and 0.65 during dynamic condition, respectively. We concluded that the postural stability assessment using Biodex stability system demonstrates good-to-excellent test-retest reliability over a 1 week time interval.

Image-based reconstruction of the Newtonian dynamics of solar coronal ejecta

NASA Astrophysics Data System (ADS)

Uritsky, Vadim M.; Thompson, Barbara J.

2016-10-01

We present a new methodology for analyzing rising and falling dynamics of unstable coronal material as represented by high-cadence SDO AIA images. The technique involves an adaptive spatiotemporal tracking of propagating intensity gradients and their characterization in terms of time-evolving areas swept out by the position vector originated from the Sun disk center. The measured values of the areal velocity and acceleration are used to obtain quantitative information on the angular momentum and acceleration along the paths of the rising and falling coronal plasma. In the absence of other forces, solar gravitation results in purely ballistic motions consistent with the Kepler's second law; non-central forces such as the Lorentz force introduce non-zero torques resulting in more complex motions. The developed algorithms enable direct evaluation of the line-of-sight component of the net torque applied to a unit mass of the ejected coronal material which is proportional to the image-plane projection of the observed areal acceleration. The current implementation of the method cannot reliably distinguish torque modulations caused by the coronal force field from those imposed by abrupt changes of plasma mass density and nontrivial projection effects. However, it can provide valid observational constraints on the evolution of large-scale unstable magnetic topologies driving major solar-coronal eruptions as demonstrated in the related talk by B. Thompson et al.

Evaluation of localized muscle fatigue using power spectral density analysis of the electromyogram

NASA Technical Reports Server (NTRS)

Lafevers, E. V.

1974-01-01

Surface electromyograms (EMGs) taken from three upper torso muscles during a push-pull task were analyzed by a power spectral density technique to determine the operational feasibility of the technique for identifying changes in the EMGs resulting from muscular fatigue. The EMGs were taken from four subjects under two conditions (1) in shirtsleeves and (2) in a pressurized space suit. This study confirmed that frequency analysis of dynamic muscle activity is capable of providing reliable data for many industrial applications where fatigue may be of practical interest. The results showed significant effects of the pressurized space suit on the pattern of shirtsleeve fatigue responses of the muscles. The data also revealed (1) reliable differences between muscles in fatigue-induced responses to various locations in the reach envelope at which the subjects were required to perform the push-pull exercise and (2) the differential sensitivity of muscles to the various reach positions in terms of fatigue-related shifts in EMG power.

Structural, electronic, and dynamical properties of liquid water by ab initio molecular dynamics based on SCAN functional within the canonical ensemble

NASA Astrophysics Data System (ADS)

Zheng, Lixin; Chen, Mohan; Sun, Zhaoru; Ko, Hsin-Yu; Santra, Biswajit; Dhuvad, Pratikkumar; Wu, Xifan

2018-04-01

We perform ab initio molecular dynamics (AIMD) simulation of liquid water in the canonical ensemble at ambient conditions using the strongly constrained and appropriately normed (SCAN) meta-generalized-gradient approximation (GGA) functional approximation and carry out systematic comparisons with the results obtained from the GGA-level Perdew-Burke-Ernzerhof (PBE) functional and Tkatchenko-Scheffler van der Waals (vdW) dispersion correction inclusive PBE functional. We analyze various properties of liquid water including radial distribution functions, oxygen-oxygen-oxygen triplet angular distribution, tetrahedrality, hydrogen bonds, diffusion coefficients, ring statistics, density of states, band gaps, and dipole moments. We find that the SCAN functional is generally more accurate than the other two functionals for liquid water by not only capturing the intermediate-range vdW interactions but also mitigating the overly strong hydrogen bonds prescribed in PBE simulations. We also compare the results of SCAN-based AIMD simulations in the canonical and isothermal-isobaric ensembles. Our results suggest that SCAN provides a reliable description for most structural, electronic, and dynamical properties in liquid water.

Dynamics and control of cable-suspended parallel robots for giant telescopes

NASA Astrophysics Data System (ADS)

Zhuang, Peng; Yao, Zhengqiu

2006-06-01

A cable-suspended parallel robot utilizes the basic idea of Stewart platform but replaces parallel links with cables and linear actuators with winches. It has many advantages over a conventional crane. The concept of applying a cable-suspended parallel robot into the construction and maintenance of giant telescope is presented in this paper. Compared with the mass and travel of the moving platform of the robot, the mass and deformation of the cables can be disregarded. Based on the premises, the kinematic and dynamic models of the robot are built. Through simulation, the inertia and gravity of moving platform are found to have dominant effect on the dynamic characteristic of the robot, while the dynamics of actuators can be disregarded, so a simplified dynamic model applicable to real-time control is obtained. Moreover, according to control-law partitioning approach and optimization theory, a workspace model-based controller is proposed considering the characteristic that the cables can only pull but not push. The simulation results indicate that the controller possesses good accuracy in pose and speed tracking, and keeps the cables in reliable tension by maintaining the minimum strain above a certain given value, thus ensures smooth motion and accurate localization for moving platform.

Access Selection Algorithm of Heterogeneous Wireless Networks for Smart Distribution Grid Based on Entropy-Weight and Rough Set

NASA Astrophysics Data System (ADS)

Xiang, Min; Qu, Qinqin; Chen, Cheng; Tian, Li; Zeng, Lingkang

2017-11-01

To improve the reliability of communication service in smart distribution grid (SDG), an access selection algorithm based on dynamic network status and different service types for heterogeneous wireless networks was proposed. The network performance index values were obtained in real time by multimode terminal and the variation trend of index values was analyzed by the growth matrix. The index weights were calculated by entropy-weight and then modified by rough set to get the final weights. Combining the grey relational analysis to sort the candidate networks, and the optimum communication network is selected. Simulation results show that the proposed algorithm can implement dynamically access selection in heterogeneous wireless networks of SDG effectively and reduce the network blocking probability.

Integrated Positioning for Coal Mining Machinery in Enclosed Underground Mine Based on SINS/WSN

PubMed Central

Hui, Jing; Wu, Lei; Yan, Wenxu; Zhou, Lijuan

2014-01-01

To realize dynamic positioning of the shearer, a new method based on SINS/WSN is studied in this paper. Firstly, the shearer movement model is built and running regularity of the shearer in coal mining face has been mastered. Secondly, as external calibration of SINS using GPS is infeasible in enclosed underground mine, WSN positioning strategy is proposed to eliminate accumulative error produced by SINS; then the corresponding coupling model is established. Finally, positioning performance is analyzed by simulation and experiment. Results show that attitude angle and position of the shearer can be real-timely tracked by integrated positioning strategy based on SINS/WSN, and positioning precision meet the demand of actual working condition. PMID:24574891

Phase synchronization based minimum spanning trees for analysis of financial time series with nonlinear correlations

NASA Astrophysics Data System (ADS)

Radhakrishnan, Srinivasan; Duvvuru, Arjun; Sultornsanee, Sivarit; Kamarthi, Sagar

2016-02-01

The cross correlation coefficient has been widely applied in financial time series analysis, in specific, for understanding chaotic behaviour in terms of stock price and index movements during crisis periods. To better understand time series correlation dynamics, the cross correlation matrices are represented as networks, in which a node stands for an individual time series and a link indicates cross correlation between a pair of nodes. These networks are converted into simpler trees using different schemes. In this context, Minimum Spanning Trees (MST) are the most favoured tree structures because of their ability to preserve all the nodes and thereby retain essential information imbued in the network. Although cross correlations underlying MSTs capture essential information, they do not faithfully capture dynamic behaviour embedded in the time series data of financial systems because cross correlation is a reliable measure only if the relationship between the time series is linear. To address the issue, this work investigates a new measure called phase synchronization (PS) for establishing correlations among different time series which relate to one another, linearly or nonlinearly. In this approach the strength of a link between a pair of time series (nodes) is determined by the level of phase synchronization between them. We compare the performance of phase synchronization based MST with cross correlation based MST along selected network measures across temporal frame that includes economically good and crisis periods. We observe agreement in the directionality of the results across these two methods. They show similar trends, upward or downward, when comparing selected network measures. Though both the methods give similar trends, the phase synchronization based MST is a more reliable representation of the dynamic behaviour of financial systems than the cross correlation based MST because of the former's ability to quantify nonlinear relationships among time series or relations among phase shifted time series.

A Target-Less Vision-Based Displacement Sensor Based on Image Convex Hull Optimization for Measuring the Dynamic Response of Building Structures.

PubMed

Choi, Insub; Kim, JunHee; Kim, Donghyun

2016-12-08

Existing vision-based displacement sensors (VDSs) extract displacement data through changes in the movement of a target that is identified within the image using natural or artificial structure markers. A target-less vision-based displacement sensor (hereafter called "TVDS") is proposed. It can extract displacement data without targets, which then serve as feature points in the image of the structure. The TVDS can extract and track the feature points without the target in the image through image convex hull optimization, which is done to adjust the threshold values and to optimize them so that they can have the same convex hull in every image frame and so that the center of the convex hull is the feature point. In addition, the pixel coordinates of the feature point can be converted to physical coordinates through a scaling factor map calculated based on the distance, angle, and focal length between the camera and target. The accuracy of the proposed scaling factor map was verified through an experiment in which the diameter of a circular marker was estimated. A white-noise excitation test was conducted, and the reliability of the displacement data obtained from the TVDS was analyzed by comparing the displacement data of the structure measured with a laser displacement sensor (LDS). The dynamic characteristics of the structure, such as the mode shape and natural frequency, were extracted using the obtained displacement data, and were compared with the numerical analysis results. TVDS yielded highly reliable displacement data and highly accurate dynamic characteristics, such as the natural frequency and mode shape of the structure. As the proposed TVDS can easily extract the displacement data even without artificial or natural markers, it has the advantage of extracting displacement data from any portion of the structure in the image.

Knowledge-based personalized search engine for the Web-based Human Musculoskeletal System Resources (HMSR) in biomechanics.

PubMed

Dao, Tien Tuan; Hoang, Tuan Nha; Ta, Xuan Hien; Tho, Marie Christine Ho Ba

2013-02-01

Human musculoskeletal system resources of the human body are valuable for the learning and medical purposes. Internet-based information from conventional search engines such as Google or Yahoo cannot response to the need of useful, accurate, reliable and good-quality human musculoskeletal resources related to medical processes, pathological knowledge and practical expertise. In this present work, an advanced knowledge-based personalized search engine was developed. Our search engine was based on a client-server multi-layer multi-agent architecture and the principle of semantic web services to acquire dynamically accurate and reliable HMSR information by a semantic processing and visualization approach. A security-enhanced mechanism was applied to protect the medical information. A multi-agent crawler was implemented to develop a content-based database of HMSR information. A new semantic-based PageRank score with related mathematical formulas were also defined and implemented. As the results, semantic web service descriptions were presented in OWL, WSDL and OWL-S formats. Operational scenarios with related web-based interfaces for personal computers and mobile devices were presented and analyzed. Functional comparison between our knowledge-based search engine, a conventional search engine and a semantic search engine showed the originality and the robustness of our knowledge-based personalized search engine. In fact, our knowledge-based personalized search engine allows different users such as orthopedic patient and experts or healthcare system managers or medical students to access remotely into useful, accurate, reliable and good-quality HMSR information for their learning and medical purposes. Copyright © 2012 Elsevier Inc. All rights reserved.

Virtual Passive Controller for Robot Systems Using Joint Torque Sensors

NASA Technical Reports Server (NTRS)

Aldridge, Hal A.; Juang, Jer-Nan

1997-01-01

This paper presents a control method based on virtual passive dynamic control that will stabilize a robot manipulator using joint torque sensors and a simple joint model. The method does not require joint position or velocity feedback for stabilization. The proposed control method is stable in the sense of Lyaponov. The control method was implemented on several joints of a laboratory robot. The controller showed good stability robustness to system parameter error and to the exclusion of nonlinear dynamic effects on the joints. The controller enhanced position tracking performance and, in the absence of position control, dissipated joint energy.

Application of a swarm-based approach for phase unwrapping

NASA Astrophysics Data System (ADS)

da S. Maciel, Lucas; Albertazzi G., Armando, Jr.

2014-07-01

An algorithm for phase unwrapping based on swarm intelligence is proposed. The novel approach is based on the emergent behavior of swarms. This behavior is the result of the interactions between independent agents following a simple set of rules and is regarded as fast, flexible and robust. The rules here were designed with two purposes. Firstly, the collective behavior must result in a reliable map of the unwrapped phase. The unwrapping reliability was evaluated by each agent during run-time, based on the quality of the neighboring pixels. In addition, the rule set must result in a behavior that focuses on wrapped regions. Stigmergy and communication rules were implemented in order to enable each agent to seek less worked areas of the image. The agents were modeled as Finite-State Machines. Based on the availability of unwrappable pixels, each agent assumed a different state in order to better adapt itself to the surroundings. The implemented rule set was able to fulfill the requirements on reliability and focused unwrapping. The unwrapped phase map was comparable to those from established methods as the agents were able to reliably evaluate each pixel quality. Also, the unwrapping behavior, being observed in real time, was able to focus on workable areas as the agents communicated in order to find less traveled regions. The results were very positive for such a new approach to the phase unwrapping problem. Finally, the authors see great potential for future developments concerning the flexibility, robustness and processing times of the swarm-based algorithm.

The temporal dynamics of ambivalence: changes in positive and negative affect in relation to consumption of an "emotionally charged" food.

PubMed

Hormes, Julia M; Rozin, Paul

2011-08-01

Ambivalence is thought to impact consumption of food, alcohol and drugs, possibly via influences on craving, with cravers often being simultaneously drawn toward and repelled from ingestion. So far, little is known about the temporal dynamics of ambivalence, especially as it varies in relationship to consumption. Participants (n=482, 56.8% female) completed the Positive and Negative Affect Schedule prior to, immediately and 30 min after the opportunity to eat a bar of chocolate. Affective ambivalence was calculated based on the relative strengths of and discrepancy between ratings of positive and negative affect. Ambivalence peaked prior to a decision about consumption and subsequently decreased, whether or not the decision was in favor of or against consuming. Decreasing ambivalence was driven by a drop in positive affect over time; positivity decreased more rapidly in those who consumed chocolate. Findings represent a first step in characterizing the dynamics of ambivalence in interactions with a target stimulus. Copyright © 2011 Elsevier Ltd. All rights reserved.

Test Performance and Test-Retest Reliability of the Vestibular/Ocular Motor Screening and King-Devick Test in Adolescent Athletes During a Competitive Sport Season.

PubMed

Worts, Phillip R; Schatz, Philip; Burkhart, Scott O

2018-05-01

The Vestibular/Ocular Motor Screening (VOMS) and King-Devick (K-D) test are tools designed to assess ocular or vestibular function after a sport-related concussion. To determine the test-retest reliability and rate of false-positive results of the VOMS and K-D test in a healthy athlete sample. Cohort study (diagnosis); Level of evidence, 2. Forty-five healthy high school student-athletes (mean age, 16.11 ± 1.43 years) completed self-reported demographics and medical history and were administered the VOMS and K-D test during rest on day 1 (baseline). The VOMS and K-D test were administered again once during rest (prepractice) and once within 5 minutes of removal from sport practice on day 2 (removal). The Borg rating of perceived exertion scale was administered at removal. Intraclass correlation coefficients were used to determine test-retest reliability on the K-D test and the average near point of convergence (NPC) distance on the VOMS. Level of agreement was used to examine VOMS symptom provocation over the 3 administration times. Multivariate base rates were used to determine the rate of false-positive results when simultaneously considering multiple clinical cutoffs. Test-retest reliability of total time on the K-D test (0.91 [95% CI, 0.86-0.95]) and NPC distance (0.91 [95% CI, 0.85-0.95]) was high across the 3 administration times. Level of agreement ranged from 48.9% to 88.9% across all 3 times for the VOMS items. Using established clinical cutoffs, false-positive results occurred in 2% of the sample using the VOMS at removal and 36% using the K-D test. The VOMS displayed a false-positive rate of 2% in this high school student-athlete cohort. The K-D test's false-positive rate was 36% while maintaining a high level of test-retest reliability (0.91). Results from this study support future investigation of VOMS administration in an acutely injured high school athletic sample. Going forward, the VOMS may be more stable than other neurological and symptom report screening measures and less vulnerable to false-positive results than the K-D test.

Assurance of reliability and safety in liquid hydrocarbons marine transportation and storing

NASA Astrophysics Data System (ADS)

Korshunov, G. I.; Polyakov, S. L.; Shunmin, Li

2017-10-01

The problems of assurance of safety and reliability in the liquid hydrocarbons marine transportation and storing are described. The requirements of standard IEC61511 have to be fulfilled for the load/unload in tanker’s system under dynamic loads on the pipeline system. The safety zones for fires of the type “fireball” and the spillage have to be determined when storing the liquid hydrocarbons. An example of the achieved necessary safety level of the duplicated load system, the conditions of the pipelines reliable operation under dynamic loads, the principles of the method of the liquid hydrocarbons storage safety zones under possible accident conditions are represented.