No description available.

No description available.

No description available.

Os controladores Proporcional+Integral+Derivativo (PID) são largamente empregados na indústria devido à sua estrutura contendo ações integral e derivativa e por possuir ordem fixa. Na literatura, encontram-se vários métodos para a sua sintonia. Nesse trabalho é apresentada uma forma de obter a sintonia do PID utilizando o índice de desempenho H∞ de forma não-iterativa. Essa sintonia é feita utilizando-se a representação em espaço de estado na forma canônica controlável. No entanto, como trata-se de um controlador de ordem fixa, variações na planta podem interferir de forma significativa no desempenho desejado e precisam ser compensadas. Assim, propõe-se também uma adaptação dos parâmetros do PID de modo a manter a função de transferência de malha fechada o mais próximo possível da nominal utilizada na sintonia. Para isso, modela-se a estrutura de controle como um sistema linear sobre-determinado com restrições lineares, advindos de conjuntos estabilizantes baseados no conceito de assinatura Hurwitz, e utiliza-se um método de otimização quadrática para obter os parâmetros do controlador. Para circunvir o conservadorismo da norma H∞, um método para mitigar apenas o efeito de algumas harmônicas na saída do sistema também é proposto, restringindo-se a sensibilidade do sistema que é representada por elipses no lugar geométrico dos ganhos estabilizantes do PID. Simulações no software Matlab, Simulink e PSIM foram utilizadas para validar os modelos e metodologias propostas. Resultados experimentais demonstraram a eficácia do método para mitigação de harmônicos em um conversor CC–CC do tipo boost. / Proportional + integral + derivative (PID) controllers are widely used in the industry due to their structure containing integral and derivative actions and for having a fixed order. In the literature, there are several methods for PID tuning. In this work it is presented a way to obtain PID tuning using a non-iterative H∞ design. This tuning is done using the state-space representation in the controllable canonical form. However, because it is a fixed-order controller, plant variations can significantly interfere with the desired performance and need to be compensated. Thus, it is also proposed to adapt the PID parameters so as to keep the closed-loop transfer function as close as possible to the nominal used in the tuning. For this, the control structure is modeled as an over-determined linear system with linear constraints, derived from stabilizing sets based on the Hurwitz signature concept, and a quadratic optimization method is used to obtain the controller parameters. In order to circumvent the conservatism of the norm H∞, a method to mitigate only the effect of selected harmonics on the output of the system is also proposed, constraining the sensitivity function of the system which is represented by ellipses in the stabilizing gains locus of the PID. Simulations in Matlab, Simulink and PSIM softwares were used to validate the proposed models and methodologies. Experimental results demonstrated the effectiveness of the harmonic mitigation method in a boost DC–DC converter.

This study aimed at finding the associates of social deviance and violence by using the variables of self-esteem, coping styles, social support, family relations, and life events in Turkish prisoner sample. The prisoners were a hundred male prisoners who are under arrest for different crimes, in istanbul Special Type Prison. Preceding the main analyses, Factor Analyses for Multidimensional Perceived Social Support (MSPSS) and Ways of Coping Scale (WOCS) were conducted. These analyses yielded three factors for MSPSS, as social support from friend, social support from a significant other, and social support from family / and two factors for WOCS, as problem focused and emotion focused coping. Analysis of Variance (ANOVA) was conducted to examine the type of crime differences for the measures of the study. The offenders were separated into two groups according to their crimes: violent and nonviolent crimes. The prisoners who acted nonviolently scored significantly higher in self-esteem scores. Prisoners that acted violent crimes were significantly more depressed and they show significantly more antisocial behavior than the prisoners that acted in nonviolent crimes. There was no significant difference found between the two groups in terms of their anxiety levels. Results indicated a main effect for social support, coping style, and family relations. To understand social deviance through the variables of the present study, a hierarchical regression was performed. The results indicated that presence of previous suicide attempts, unhealthy relations in the family, physical violence in the family towards the subject, the scores gathered from depression and paranoia subscales of MMPI, anxiety scores on BAI, hypomania scores on MMPI were found to account for 59% of the total variance in social deviance in terms of higher scores on psychopathic deviate subscale of MMPI.

Obsidian has been a center of interest both for geologists and archaeologists. Geologists have studied on physical and chemical properties of obsidian where archaeologists have worked on this material as a common artifact found in excavations. In this study, obsidian samples from &Ccedil / atalh&ouml / y&uuml / k excavations are examined using their rare earth element (REE) concentrations. Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) have been used for this purpose. A mixture (4:1) of lithium metaborate and lithium tetraborate was used for fusion of samples. Because of the low concentrations of REEs, a preconcentration step is needed. Successful recovery results have been achieved with Amberlite IR-120. The developed method is tested using the standard reference material SARM-1.

The main objective of this study is to model and analyze a three dimensional inclined semi-elliptic surface crack in a Functionally Graded Material (FGM) coating bonded to a homogeneous substrate with a bond coat. The parametric analyses on FGMs are based upon zirconia-yttria (ZrO2-8wt%-Y2O3) FGM coating bonded to a substrate made of a nickel-based superalloy. It is assumed that there is a nickel-chromium&amp / #8211 / aluminum&amp / #8211 / zirconium (NiCrAlY) bond coat between the FGM coating and substrate. Metal-rich, linear variation, ceramic-rich and homogeneous ceramic FGM coating types are considered in the analyses. The inclined semi-elliptic surface crack problem in the FGM coating-bond coat-substrate system is analyzed under transient thermal loading. This problem is modeled and analyzed by utilizing three dimensional finite elements. Strain singularity around the crack front is simulated using collapsed 20 &amp / #8211 / node quarter &amp / #8211 / point brick elements. Three &amp / #8211 / dimensional displacement correlation technique is utilized to extract the mixed mode stress intensity factors around the crack front for different inclination angles of the semi-elliptic surface crack. The energy release rates around the crack front are also calculated by using the evaluated mixed mode stress intensity factors. The results obtained in this study are the peak values of mixed mode stress intensity factors and energy release rates around the crack front for various inclination angles of the semi-elliptic surface crack embedded in the FGM coating of the composite structure subjected to transient thermal loading.

No description available.

No description available.

No description available.