A model of seam pucker and its applications Part I: theoretical

Abstract

This article considers a simple model of the lock stitch (301) seam, and uses it to derive a measure of the severity of puckering in the seam. The numerical value of the measure depends on the bending properties of the fabrics and thread in the seam, together with the tensions in the threads. How the latter may be estimated is discussed.     

Violence classifications and their impact on observed relationships with key factors in young offenders.

The understanding of violent criminal behavior is hindered by definitional problems in both the legal and research communities. Different definitions of violent criminal behavior and different classifications of the severity of violence are fundamental problems that need to be resolved in order to develop better conceptual models of the precursors to criminal violence that can inform management and treatment of violent young offenders. This study evaluated 6 classifications of violent juvenile offenses derived from the legal system and published research. The authors compare frequencies from different classifications and examine the influence of classifications on observed associations with expected predictor variables. Differences in frequencies and perceived associations between classifications highlight the need to adopt a consistent method of coding violent offenses for research purposes in order to obtain valid results that are capable of informing policy, the judiciary, and the development of effective interventions. The final classification system offers a method of systematic coding based on the type, frequency, and outcome of the violent behavior that distinguishes between levels of violence severity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender and posttraumatic stress: Sexual violence as an explanation for women's increased risk.

Women are approximately twice as likely as men to develop posttraumatic stress disorder (PTSD), but the cause of this disparity remains unclear. This study evaluated 2 alternative explanations of gender differences in PTSD, one pointing to an intrinsic vulnerability in women and the other emphasizing sexual violence across the life span. To test these competing theories, the authors analyzed National Violence Against Women Survey data from 591 victims of partner aggression. Results suggested that gender, when considered alone, has a small but significant effect on PTSD symptom severity. However, once models factor in sexual victimization history, the latter replaces gender as a key determinant of PTSD symptoms. These findings argue against theories of "feminine vulnerability," instead linking PTSD risk to sexually violent situations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Factors associated with the likelihood of injury resulting from collisions between four-wheel drive vehicles and passenger cars

The specific effects of vehicular type on the likelihood of an injury occurring are relatively unexplored. This study sought to assess the relative risk of injury to occupants of four-wheel drive vehicles and their counterparts in passenger cars.Data for 1143 occupants from all of the 454 crashes in Oklahoma, in 1995 that involved a four-wheel drive vehicle were used. Multiple logistic regression analysis determined the association between potential predictive factors and vehicular injury. Odds ratios revealed occupancy in a passenger car to be a major predictor of the likelihood of injury. Other factors include the driver being female, driving too fast, travel on curved or level roadways, and being hit laterally or from the rear.     

Coping style use predicts posttraumatic stress and complicated grief symptom severity among college students reporting a traumatic loss.

Problem-focused coping, and active and avoidant emotional coping were examined as correlates of grief and posttraumatic stress disorder (PTSD) severity among 123 college students reporting the unexpected death of an immediate family member, romantic partner, or very close friend. The authors administered to participants, via the Internet, 5 survey instruments that measured demographic characteristics, traumatic event exposure (Stressful Life Events Screening Questionnaire; L. Goodman, C. Corcoran, K. Turner, N. Yuan, & B. L. Green, 1998), complicated grief (CG) severity (Inventory of Complicated Grief--Revised--Short Form; A. E. Latham & H. G. Prigerson, 2004; H. G. Prigerson & S. C. Jacobs, 2001), PTSD severity (PTSD Checklist; F. W. Weathers, B. T. Litz, D. S. Herman, J. A. Huska, & T. M. Keane, 1993), and coping style use (Brief COPE; C. S. Carver, 1997). Results demonstrated that CG and PTSD severity were both significantly positively correlated with problem-focused, and active and avoidant emotional coping styles. The authors used path analysis to control for time since the loss and trauma frequency and found that only avoidant emotional coping remained significant in predicting CG and PTSD severity. Results are discussed in terms of their clinical implications for treating individuals with traumatic losses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fuzzy Reliability Assessment of Distribution System with Wind Farms and Plug-in Electric Vehicles

Abstract

The equipment failures are highly uncertain in nature and simple average failure rate will not reflect this uncertainty. The uncertainty level further increases in reliability evaluation due to the integration of wind farm (WF) because of the intermittent nature of wind speed and random charging patterns of plug-in electric vehicles (PEVs). In this work, the uncertain variables in the distribution system (failure rate, repair time, WF output, PEVs charging and system load factor) are represented as fuzzy numbers to handle the uncertainty. The available uncertain data are used to find the probability distribution function (PDF) of that parameter and is converted into fuzzy membership function using transformation techniques. Failure rate of equipment is converted into failure probability using Monte Carlo simulation (MCS) method. Sampling method is applied to create the PDF of a variable which has average value. Fuzzy severity index (FSI) is proposed to find the importance of an equipment on reliability and is evaluated by measuring the fuzzy distance between the fuzzy reliability indices. The proposed assessment method is validated on modified RBTS bus 2 by comparing with analytical and MCS methods. The proposed method has been tested with integration of WFs and PEVs.     

Prediction parameters of dimensioning of insulators under non-uniform contaminated conditions by multiple regression analysis

Surface tracking on solid insulators is one of the most severe breakdown mechanisms. Accurate assessment of real insulation conditions can be achieved by using the statistical techniques that assist the measurement and monitoring of contamination severity, flashover voltage and leakage current.To address the uncertainties that surround the exact physical mechanisms underlying the mathematical models, it has been shown that it is possible to include in the assessment of insulator performance contamination accumulation that is predicted by using a short historical of chemical components and atmospheric conditions. The results from this work are useful to predict the contamination severity, flashover voltage as a function of contamination severity, leakage current as a function of applied voltage, arc length and contamination severity, and especially to predict the flashover current.     

Estimation of Drought Severity on Independent and Dependent Hydrologic Series

The drought severity is the most important parameter for the design of water storage systems in order to alleviate the water shortages during drought periods. The largest drought severity, i.e. severity of a worst drought at a desired truncation level and for the desired return period can be estimated using the truncated normal distribution of the deficits in individual drought years, Poisson distribution of the number of drought spells over a period of T years and geometric distribution of drought duration. The analysis can be done for random or Markovian structure of drought variable (annual rainfall or runoff sequences) distributed normally or lognormally. The study indicated that the severity at a high truncation level is larger than that at a low truncation level over any desired return period T. Severity is also larger in the case of autocorrelated drought variable. A frequency formula for the largest drought severity can be formulated analogous to the flood frequency formula commonly found in the hydrologic texts.     

基于多小波包样本熵的轴承损伤程度识别方法

为了自动辨识不同尺度下的轴承故障,建立了一种基于多小波包系数样本熵和BP神经网络的模式判别方法。针对5种尺度下的轴承外圈故障信号,分别采用GHM多小波包完成三层分解。为了充分利用多小波包的分析优势,将分解后的16个频段信号分别求系数样本熵,并将其作为神经网络的输入向量。通过三层BP神经网络的训练、学习,并与dB10小波包神经网络做了对比研究。结果表明,多小波包样本熵可以区别不同损伤程度的故障信号,且多小波包样本熵与神经网络结合,其辨识精度更高,分类效果明显优于传统单小波,便于轴承损伤程度的自动识别。