scholarly journals Repetitive Identification of Structural Systems Using a Nonlinear Model Parameter Refinement Approach

2009 ◽  
Vol 16 (3) ◽  
pp. 229-240 ◽  
Author(s):  
Jeng-Wen Lin ◽  
Hung-Jen Chen
Keyword(s):  
Power Series ◽  
Confidence Interval ◽  
Nonlinear Model ◽  
Health Monitoring ◽  
Structural Parameters ◽  
Statistical Significance ◽  
Structural Systems ◽  
Statistical Regression ◽  
Model Refinement ◽  
Model Parameter

This paper proposes a statistical confidence interval based nonlinear model parameter refinement approach for the health monitoring of structural systems subjected to seismic excitations. The developed model refinement approach uses the 95% confidence interval of the estimated structural parameters to determine their statistical significance in a least-squares regression setting. When the parameters' confidence interval covers the zero value, it is statistically sustainable to truncate such parameters. The remaining parameters will repetitively undergo such parameter sifting process for model refinement until all the parameters' statistical significance cannot be further improved. This newly developed model refinement approach is implemented for the series models of multivariable polynomial expansions: the linear, the Taylor series, and the power series model, leading to a more accurate identification as well as a more controllable design for system vibration control. Because the statistical regression based model refinement approach is intrinsically used to process a “batch” of data and obtain an ensemble average estimation such as the structural stiffness, the Kalman filter and one of its extended versions is introduced to the refined power series model for structural health monitoring.

Health Diagnosis of Structural Systems Using a Repetitive Model Updating Approach

2007 ◽  
Author(s):  
Jeng-Wen Lin ◽  
Chong-Shien Tsai ◽  
Chih-Wei Huang
Keyword(s):  
Confidence Interval ◽  
Model Updating ◽  
Structural Parameters ◽  
Statistical Significance ◽  
Structural Systems ◽  
Least Squares Regression ◽  
Accurate Identification ◽  
Statistical Confidence ◽  
Multivariable Polynomial ◽  
Health Diagnosis

This paper proposes a statistical confidence interval based model updating approach for the health diagnosis of structural systems subjected to seismic excitations. The proposed model updating approach uses the 95% confidence interval of the estimated structural parameters to determine their statistical significance in a least-squares regression setting. When the parameters’ confidence interval covers the “null” value, it is statistically sustainable to truncate such parameters. The remaining parameters will repetitively undergo such parameter sifting process for model updating until all the parameters’ statistical significance cannot be further improved. This newly developed model updating approach is implemented for the developed series models of multivariable polynomial expansions: the linear, the Taylor series, and the power series model, leading to a more accurate identification as well as a more controllable design for system vibration control.

Identification of Structural Systems Under Tri-Directional Seismic Excitations Using a Statistically Refined Bouc-Wen Model

2007 ◽  
Author(s):  
Jeng-Wen Lin ◽  
Chong-Shien Tsai ◽  
Wen-Shin Chen
Keyword(s):  
Earthquake Engineering ◽  
Sampling Error ◽  
Structural Parameters ◽  
Statistical Significance ◽  
Structural Systems ◽  
Seismic Excitations ◽  
Estimated Parameters ◽  
Restoring Forces ◽  
System Vibration ◽  
Axial Interaction

This paper presents the identification of structural systems under tri-directional seismic excitations using a statistically refined Bouc-Wen model of tri-axial interaction. Through limited vibration measurements in the National Center for Research on Earthquake Engineering in Taiwan, the Bouc-Wen model has been statistically and repetitively refined using the 95% confidence interval of the estimated structural parameters so as to determine their statistical significance in a multiple regression setting. The effectiveness of the refined model has been shown considering the effects of the sampling error, of the coupled restoring forces in tri-directions, and of the under-over-parameterization of structural systems. Sifted and estimated parameters such as the stiffness, and its corresponding natural frequency, resulting from the methodology developed in this paper are carefully observed for system vibration control.

scholarly journals Structural Reliability Sensitivities under Nonstationary Random Vibrations

2013 ◽  
Vol 2013 ◽  
pp. 1-21 ◽  
Author(s):  
Rita Greco ◽  
Francesco Trentadue
Keyword(s):  
Structural Reliability ◽  
Structural Parameters ◽  
Time Integration ◽  
Structural Response ◽  
Integration Scheme ◽  
Structural Systems ◽  
Frame Building ◽  
Time Integration Scheme ◽  
Noise Input ◽  
The Time Domain

Response sensitivity evaluation is an important element in reliability evaluation and design optimization of structural systems. It has been widely studied under static and dynamic forcing conditions with deterministic input data. In this paper, structural response and reliability sensitivities are determined by means of the time domain covariance analysis in both classically and nonclassically damped linear structural systems. A time integration scheme is proposed for covariance sensitivity. A modulated, filtered, white noise input process is adopted to model the stochastic nonstationary loads. The method allows for the evaluation of sensitivity statistics of different quantities of dynamic response with respect to structural parameters. Finally, numerical examples are presented regarding a multistorey shear frame building.

scholarly journals Protozoa enumeration via microscope – some remarks on methodology

2018 ◽  
Vol 44 ◽  
pp. 00121
Author(s):  
Sara Nicpoń ◽  
Paula Iliaszewicz ◽  
Maciej Leoniak ◽  
Agnieszka Trusz-Zdybek
Keyword(s):  
Confidence Interval ◽  
Activated Sludge ◽  
Sharp Increase ◽  
Statistical Significance ◽  
Lower Number ◽  
Average Confidence ◽  
Statistical Results

For proper enumeration of protozoa in activated sludge good methodology is required. In this paper we present some remarks on microscopic methodology of protozoa enumeration. This remarks concern number of repetitions from one sample required to obtain good statistical results as well as influence of sample aeration on number of found protozoa. Presented data shows that at last 10 repetitions are required from each sample to obtain low average confidence interval. Lower number of repetitions leads to sharp increase in average confidence interval and loss of statistical significance while higher number does not decrease average confidence interval substantially. As measurements lasts for few hours lack of sample’s aeration during measurement leads to detection of lower by 27% number of protozoa.

scholarly journals Experimental Validation of Optimal Parameter and Uncertainty Estimation for Structural Systems Using a Shuffled Complex Evolution Metropolis Algorithm

2019 ◽  
Vol 9 (22) ◽  
pp. 4959 ◽  
Author(s):  
Hesheng Tang ◽  
Xueyuan Guo ◽  
Liyu Xie ◽  
Songtao Xue
Keyword(s):  
Optimal Parameter ◽  
Structural Parameters ◽  
Metropolis Algorithm ◽  
Shaking Table ◽  
Parameter Distribution ◽  
Physical Parameters ◽  
Structural Systems ◽  
Model Errors ◽  
Nonlinear Structural ◽  
Shuffled Complex Evolution

The uncertainty in parameter estimation arises from structural systems’ input and output measured errors and from structural model errors. An experimental verification of the shuffled complex evolution metropolis algorithm (SCEM-UA) for identifying the optimal parameters of structural systems and estimating their uncertainty is presented. First, the estimation framework is theoretically developed. The SCEM-UA algorithm is employed to search through feasible parameters’ space and to infer the posterior distribution of the parameters automatically. The resulting posterior parameter distribution then provides the most likely estimation of parameter sets that produces the best model performance. The algorithm is subsequently validated through both numerical simulation and shaking table experiment for estimating the parameters of structural systems considering the uncertainty of available information. Finally, the proposed algorithm is extended to identify the uncertain physical parameters of a nonlinear structural system with a particle mass tuned damper (PTMD). The results demonstrate that the proposed algorithm can effectively estimate parameters with uncertainty for nonlinear structural systems, and it has a stronger anti-noise capability. Notably, the SCEM-UA method not only shows better global optimization capability compared with other heuristic optimization methods, but it also has the ability to simultaneously estimate the uncertainties associated with the posterior distributions of the structural parameters within a single optimization run.

Optimal Accelerometer Locations for Structural Health Monitoring Using Time-Domain System Identification

2006 ◽  
Vol 321-323 ◽  
pp. 273-277 ◽  
Author(s):  
Soon Jung Kwon ◽  
Hae Sung Lee ◽  
Soo Bong Shin
Keyword(s):  
System Identification ◽  
Structural Health Monitoring ◽  
Fisher Information ◽  
Health Monitoring ◽  
Time Domain ◽  
Fisher Information Matrix ◽  
Structural Parameters ◽  
Hessian Matrix ◽  
Information Matrix ◽  
Structural Health

The paper presents two algorithms for determining optimal accelerometer locations for structural health monitoring when structural condition is assessed by a system identification scheme in time-domain. The accelerometer locations are determined by ranking the components of an effective independent distribution vector computed from a Fisher information matrix. One of the proposed algorithms formulates a Fisher information matrix by multiplying acceleration matrix with its transpose and the other as a Gauss-Newton Hessian matrix composed of acceleration sensitivities with respect to structural parameters. Since the structural parameters cannot be known exactly in an actual application, a statistical approach is proposed by setting an error bound between the actual and the baseline values. To examine the algorithm, simulation studies have been carried out on a two-span planar truss. The results using locations selected by the two algorithms were compared.

Physical restraints versus seclusion room for management of people with acute aggression or agitation due to psychotic illness (TREC-SAVE): a randomized trial

2012 ◽  
Vol 42 (11) ◽  
pp. 2265-2273 ◽  
Author(s):  
G. Huf ◽  
E. S. F. Coutinho ◽  
C. E. Adams ◽  
Keyword(s):  
Health Care ◽  
Relative Risk ◽  
Confidence Interval ◽  
Care Pathway ◽  
Statistical Significance ◽  
The Other ◽  
Physical Restraints ◽  
Psychotic Illness ◽  
The People ◽  
Mean Time

BackgroundAfter de-escalation techniques have failed, restraints, seclusion and/or rapid tranquillization may be used for people whose aggression is due to psychosis. Most coercive acts of health care have not been evaluated in trials.MethodPeople admitted to the emergency room of Instituto Philippe Pinel, Rio de Janeiro, Brazil, whose aggression/agitation was thought due to psychosis and for whom staff were unsure if best to restrict using physical restraints or a seclusion room, were randomly allocated to one or the other and followed up to 14 days. The primary outcomes were ‘no need to change intervention early – within 1 h’ and ‘not restricted by 4 h’.ResultsA total of 105 people were randomized. Two-thirds of the people secluded were able to be fully managed in this way. Even taking into account the move out of seclusion into restraints, this study provides evidence that embarking on the less restrictive care pathway (seclusion) does not increase overall time in restriction of some sort [not restricted by 4 h: relative risk 1.09, 95% confidence interval 0.75–1.58; mean time to release: restraints 337.6 (s.d.=298.2) min, seclusion room 316.3 (s.d.=264.5) min, p=0.48]. Participants tended to be more satisfied with their care in the seclusion group (17.0% v. 11.1%) but this did not reach conventional levels of statistical significance (p=0.42).ConclusionsThis study should be replicated, but suggests that opting for the least restrictive option in circumstances where there is clinical doubt does not harm or prolong coercion.

Damage Identification by Embedded Piezoceramic Sensors in the Composite Plate

2006 ◽  
Vol 326-328 ◽  
pp. 1697-1700
Author(s):  
Heoung Jae Chun ◽  
Choong Hee Yi ◽  
Joon Hyung Byun
Keyword(s):  
Monitoring System ◽  
Health Monitoring ◽  
Composite Laminates ◽  
Damage Identification ◽  
Lamb Waves ◽  
Structural Systems ◽  
Detection Accuracy ◽  
Health Monitoring System ◽  
Localized Defects ◽  
The Many

The embedded structural health monitoring system is envisioned to be an important factor of future structural systems. One of the many attractions of in situ health monitoring system is its capability to inspect the structural systems in less intrusive way over many other visual inspections which require disassembly of built up structures when some indications have appeared that damages have occurred in the structural systems The vacuum assisted resin transfer molding (VARTM) process is used to fabricate woven-glass/phenol composite specimens which have the PZT sensor array embedded in them. The embedded piezoceramic (PZT) sensors are used as both transmitters and receivers. A damage identification approach is developed for a woven-glass/phenol composite laminates with known localized defects. Propagation of the Lamb waves in laminates and their interactions with the defects are examined. Lamb waves are generated by the high power ultrasonic analyzer. A real time active diagnosis system is therefore established. The results obtained show that satisfactory detection accuracy could be achieved by proposed method.

scholarly journals Identifying Strategies Programs Adopt to Meet Healthy Eating and Physical Activity Standards in Afterschool Programs

2016 ◽  
Vol 44 (4) ◽  
pp. 536-547 ◽  
Author(s):  
Robert G. Weaver ◽  
Justin B. Moore ◽  
Brie Turner-McGrievy ◽  
Ruth Saunders ◽  
Aaron Beighle ◽  
...  
Keyword(s):  
Physical Activity ◽  
Confidence Interval ◽  
Healthy Eating ◽  
Vigorous Physical Activity ◽  
Statistical Significance ◽  
National Level ◽  
Routine Practice ◽  
Afterschool Programs ◽  
Point Increase ◽  
The Relationship

Background. The YMCA of USA has adopted Healthy Eating and Physical Activity (HEPA) Standards for its afterschool programs (ASPs). Little is known about strategies YMCA ASPs are implementing to achieve Standards and these strategies’ effectiveness. Aims. (1) Identify strategies implemented in YMCA ASPs and (2) evaluate the relationship between strategy implementation and meeting Standards. Method. HEPA was measured via accelerometer (moderate-to-vigorous-physical-activity [MVPA]) and direct observation (snacks served) in 20 ASPs. Strategies were identified and mapped onto a capacity building framework ( Strategies To Enhance Practice [STEPs]). Mixed-effects regression estimated increases in HEPA outcomes as implementation increased. Model-implied estimates were calculated for high (i.e., highest implementation score achieved), moderate (median implementation score across programs), and low (lowest implementation score achieved) implementation for both HEPA separately. Results. Programs implemented a variety of strategies identified in STEPs. For every 1-point increase in implementation score 1.45% (95% confidence interval = 0.33% to 2.55%, p ≤ .001) more girls accumulated 30 min/day of MVPA and fruits and/or vegetables were served on 0.11 more days (95% confidence interval = 0.11-0.45, p ≤ .01). Relationships between implementation and other HEPA outcomes did not reach statistical significance. Still regression estimates indicated that desserts are served on 1.94 fewer days (i.e., 0.40 vs. 2.34) in the highest implementing program than the lowest implementing program and water is served 0.73 more days (i.e., 2.37 vs. 1.64). Conclusions. Adopting HEPA Standards at the national level does not lead to changes in routine practice in all programs. Practical strategies that programs could adopt to more fully comply with the HEPA Standards are identified.

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