Applications of fuzzy theories to multi-objective system optimization

Most of the computer aided design techniques developed so far deal with the optimization of a single objective function over the feasible design space. However, there often exist several engineering design problems which require a simultaneous consideration of several objective functions. This work presents several techniques of multiobjective optimization. In addition, a new formulation, based on fuzzy theories, is also introduced for the solution of multiobjective system optimization problems. The fuzzy formulation is useful in dealing with systems which are described imprecisely using fuzzy terms such as, 'sufficiently large', 'very strong', or 'satisfactory'. The proposed theory translates the imprecise linguistic statements and multiple objectives into equivalent crisp mathematical statements using fuzzy logic. The effectiveness of all the methodologies and theories presented is illustrated by formulating and solving two different engineering design problems. The first one involves the flight trajectory optimization and the main rotor design of helicopters. The second one is concerned with the integrated kinematic-dynamic synthesis of planar mechanisms. The use and effectiveness of nonlinear membership functions in fuzzy formulation is also demonstrated. The numerical results indicate that the fuzzy formulation could yield results which are qualitatively different from those provided by the crisp formulation. It is felt that the fuzzy formulation will handle real life design problems on a more rational basis

Discomfort, Pressure Distribution and Safety in Operator's Seat-A Critical Review

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is an Invited Paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 5 (2003): H. Dhingra, V. Tewari, and S. Singh. Discomfort, Pressure Distribution and Safety in Operator's Seat-A Critical Review. Vol. V. July 2003

Gender differences and correlates of extreme dieting behaviours in US adolescents.

This article examined correlates of and gender differences in extreme dieting behaviours among 15,425 US adolescents from the 2011 Youth Risk Behavior Survey. Suicidal thoughts and plans and binge drinking were related to extreme dieting behaviours in females, but not in males. Suicide attempts, daily smoking and marijuana use were related to extreme dieting behaviours in males, but not females. Results suggest extreme dieting behaviours are associated with a range of negative psychosocial factors and substance use behaviours, and that these differ for boys and girls. Additional research is required to elucidate these relationships, and these results provide a focus for future research, prevention and intervention efforts

Latent classes of delinquent behaviour associated with criminal social identity among juvenile offenders in Pakistan

© Emerald Group Publishing Limited. Purpose – The purpose of this paper is to examine the number and nature of latent classes of delinquency that exist among male juvenile offenders incarcerated in prisons in Pakistan. Design/methodology/approach – The sample consisted of 415 young male offenders incarcerated in prisons in Khyber Pakhtunkhwa (KPK) Pakistan. Latent class analysis was employed to determine the number and nature of delinquency latent classes. Multinomial logistic regression was used to estimate the associations between latent classes and the three factors of criminal social identity (cognitive centrality, in-group affect, and in-group ties) whilst controlling for criminal friends, period of confinement, addiction, age, and location. Findings – The best fitting latent class model was a three-class solution. The classes were labelled: “minor delinquents” (the baseline/normative class; Class 3), “major delinquents” (Class 1), and “moderate delinquents” (Class 2). Class membership was predicted by differing external variables. Specifically, Class 1 membership was related to having more criminal friends; while Class 2 membership was related to lower levels of in-group affect and higher levels of in-group ties. Practical implications – Findings are discussed in relation to refining current taxonomic arguments regarding the structure of delinquency and implications for prevention of juvenile delinquent behaviour. Originality/value – First, most previous studies have focused on school children, whereas, this paper focuses on incarcerated juvenile offenders. Second, this research includes delinquents from Pakistan, whereas, most previous research has examined delinquent behaviour in western cultures

Criminal social identity and suicide ideation among Pakistani young prisoners.

© Emerald Group Publishing Limited. Purpose: Suicidal behaviour is a common in prisoners, yet little is known about the factors that may protect against thoughts of ending one's life. The purpose of this paper is to specify and test a structural model to examine the relationship between three criminal social identity (CSI) dimensions (in-group affect, in-group ties, and cognitive centrality) and suicide ideation while controlling for period of confinement, age, criminal friends, and offense type (violent vs non-violent). Design/methodology/approach: Participants were 415 male juvenile offenders incarcerated in prisons in Khyber Pakhtunkhwa Pakistan. A structural model was specified and tested using Mplus to examine the relationships between the three factors of CSI and suicidal thoughts, while controlling for age, offender type, period of confinement, and substance dependence. Findings: The model provided an adequate fit for the data, explaining 22 per cent of variance in suicidal thoughts. In-group affect (the level of personal bonding with other criminals) was found to exert a strong protective effect against suicide ideation. Originality/value: The research contributes important information on suicide ideation in Pakistan, an Islamic country in which suicide is considered a sin and subsequently a criminal offence. Results indicate that Juvenile offenders' sense of shared identity may help to prevent the development of thoughts of death by suicide. Consequently, separating and isolating young prisoners may be ill advised

Methodology for finding optimum cell size for a grid based cellular automata traffic flow model

A methodology for determining optimum cell size for a grid based traffic flow model for heterogeneous traffic is proposed in this paper. The cell size is an important factor to determine as it affects the computational efficiency and model accuracy. The objective function minimizes three aspects namely the difference of distance headway in case of cellular automata and grid based traffic flow model, the total number of cells to represent different types of vehicles and multiple of cell width that gives closer representation of the different road widths. The presented method is found better then the previous attempt which tries to find the cell size by trial and error

Electromagnetic response of LaO_0.94F_0.06FeAs: AC susceptibility and microwave surface resistance

We discuss on the electromagnetic response of a polycrystalline sample of LaO_0.94F_0.06FeAs exposed to DC magnetic fields up to 10 kOe. The low- and high-frequency responses have been investigated by measuring the AC susceptibility at 100 kHz and the microwave surface resistance at 9.6 GHz. At low as well as high DC magnetic fields, the susceptibility strongly depends on the amplitude of the AC driving field, highlighting enhanced nonlinear effects. The field dependence of the AC susceptibility exhibits a magnetic hysteresis that can be justified considering the intragrain-field-penetration effects on the intergrain critical current density. The microwave surface resistance exhibits a clockwise magnetic hysteresis, which cannot be justified in the framework of the critical-state models of the Abrikosov-fluxon lattice; it may have the same origin as that detected in the susceptibility.Comment: 8 pages, 4 embedded eps figures; Proceedings of the 9th EUCAS Conference (Dresden, Germany, September 13-17, 2009

Suicide attempts among incarcerated homicide offenders

The aim was to investigate the role of age, drug abuse, period of confinement, loneliness, difficulty in controlling emotions, having no friends in prison, victimization in prison, guilt over crimes, insomnia, nightmares, anxiety, depression, and mood change in predicating suicide attempts in a sample of homicidal young prisoners. Poisson regression model indicated that five variables contributed significantly to the prediction of suicide attempts. Specifically, participants reporting drug abuse, difficulty in controlling emotions, victimization in prison, nightmares, and depression were significantly more likely to report suicide attempts while incarcerated

Psychopathy, Gang membership, And moral disengagement among juvenile offenders

Purpose – The purpose of this paper is to investigate the impact of psychopathy factors and gang membership on moral disengagement while controlling for age, ethnicity, having run away from home, family member and/or friend arrests, substance misuse, parental physical fights, violence exposure (victimization and witnessing), and maternal warmth and hostility. Design/methodology/approach – The research is based on data collected from serious juvenile offenders (n=769) as part of the Pathways to Desistance Study. Findings – Six independent variables made a unique statistically significant contribution to the model: gang membership, age, gender, violence exposure, and psychopathy Factors 1 and 2. Psychopathy Factor 1 was the strongest predictor of moral disengagement. Originality/value – Results indicate that youth with heightened psychopathic traits make greater use of strategies to rationalize and justify their harmful behaviour against others. Implications in relation to theory and previous studies are discussed