Για τη διατήρηση της διαφοράς δυναμικού μεταξύ των υπό υψηλή τάση αγώγιμων μερών επιβάλλεται η μόνωση του εξοπλισμού και των εγκαταστάσεων υψηλής τάσης. Μία ευρέως χρησιμοποιούμενη κατηγορία μονωτικών υλικών είναι τα μονωτικά υγρά. Τα πιο δημοφιλή εξ’ αυτών είναι τα ορυκτά έλαια, δηλαδή έλαια προερχόμενα από πετρέλαιο εξαιτίας της εύκολης διάθεσης τους και του σχετικά χαμηλού κόστους τους. Χρήση των μονωτικών ελαίων έχουμε σε μετασχηματιστές, ελαιοδιακόπτες, πυκνωτές, καλώδια, μονωτήρες διέλευσης και μετασχηματιστές οργάνων. Στο θεωρητικό κομμάτι της εργασίας περιγράφεται αναλυτικά η χρήση των ελαίων σε κάθε μία από τις παραπάνω συσκευές καθώς και οι φυσικές, χημικές και ηλεκτρικές ιδιότητές τους. Ακόμη αναλύονται οι τρόποι διάσπασης των μονωτικών ελαίων και συγκεκριμένα η ηλεκτρονική διάσπαση, ο μηχανισμός αιωρούμενων σωματιδίων, η διάσπαση κοιλότητας και τέλος η ηλεκτρομεταφορά και ηλεκτροϋδροδυναμικό πρότυπο διηλεκτρικής διάσπασης Υπό την επίδραση καταπονήσεων η μόνωση μπορεί να υποστεί μεταβολές (μόνιμες ή παροδικές) διαφόρων ιδιοτήτων της. Η ορθή σχεδίαση της μονώσεως προϋποθέτει τη γνώση των υπερτάσεων που αναμένεται να αναπτυχθούν σ' αυτή. Η μορφή της υπέρτασης που εξετάζεται στην παρούσα εργασία είναι η κεραυνική κρουστική τάση. Για τις ατμοσφαιρικές υπερτάσεις (κεραυνού) έχει οριστεί ως τάση δοκιμής η κρούση 1.2/50 μs γιατί η μέση τιμή πολλών καταγραφέντων ρευμάτων κεραυνού κατέληξε σε αυτή περίπου τη μορφή. Η παραγωγή των συγκεκριμένων τάσεων πραγματοποιήθηκε από τη διβάθμια κρουστική γεννήτρια του εργαστηρίου Υψηλών Τάσεων, η λειτουργία της οποίας αναλύεται στο δεύτερο κεφάλαιο. Μία επιπλέον παράμετρος που εξετάζεται στα πλαίσια της μελέτης της διηλεκτρικής αντοχής των μονωτικών ελαίων είναι ο χρόνος που παρέρχεται μεταξύ της εφαρμογής μίας τάσης σε ένα διάκενο, αρκετής να προκαλέσει διάσπαση, και της διάσπασης και ο οποίος καλείται χρονική υστέρηση. Για τη διεξαγωγή του πειράματος χρησιμοποιήθηκε η προαναφερθείσα γεννήτρια, παλμογράφος, κυψέλη από υλικό Plexιglass και ηλεκτρόδια Rogowski καθώς και ακίδας-πλάκας. Οι δοκιμές πραγματοποιήθηκαν υπό κεραυνικές κρουστικές τάσεις θετικής πολικότητας 1.2/50 μs σε έλαιο πετρελαϊκής απόσταξης Shell Diala Oil με στόχο τη διερεύνηση της συμπεριφοράς του, καθώς μεταβάλουμε τους διάφορους παράγοντες από τους οποίους εξαρτάται. Συγκεντρώσαμε μετρήσεις με στόχο την παρατήρηση της επίδρασης που ασκεί στην τάση διάσπασης, το μέγεθος του διακένου, η καταπόνηση του ελαίου, ο χρόνος ηρεμίας του καθώς και οι ατμοσφαιρικές συνθήκες. Για την επεξεργασία των μετρήσεων χρησιμοποιήθηκε πρόγραμμα γραμμένο σε γλώσσα προγραμματισμού Fortran 98, το οποίο υλοποιεί τη μέθοδο μέγιστης πιθανοφάνειας. Με βάση αυτή τη μέθοδο, εξάγουμε ακριβείς τιμές για την τάση που αντιστοιχεί σε πιθανότητα διάσπασης 50% (V50), την τυπική απόκλιση (σ) των τιμών της τάσης διάσπασης για κάθε κύκλο μετρήσεων καθώς και τη διασπορά και τα όρια αξιοπιστίας των V50 και σ. Τα αποτελέσματα παρουσιάζονται σε πίνακες και σε διαγράμματα κανονικής κατανομής. Ένας επιπλέον παράγοντας που εξετάζεται είναι η χρονική υστέρηση για συγκεκριμένα μήκη διακένου, τόσο για ομοιόμορφο πεδίο όσο και για μη ομοιόμορφο πεδίο. / Insulation of high voltage equipment and facilities is necessary in order to retain the potential difference between under high voltage conductible particles. A widely used group of insulating materials are insulating liquids. Most popular among them are fossil oils, which are made of oil, because of their easy provision and relatively low cost. Insulating oils are used in transformers, oil disruptors, condensers, cables, transit insulators and tool transformers. The theoretical part of the essay analytically describes the use of oils in each of the above appliances as well as their natural, chemical and electrical attributes. Moreover, it explicates the ways of resolution of insulating oils, especially electronic resolution, process of pendulous particles, cavity resolution and, finally, electro transfer and electro hydro-dynamic practice of dielectric resolution. Under the influence of strain, insulation may alter (permanently or impermanently) in several of its attributes. Proper design of insulation requires knowledge of hyper voltages that may occur. The form of hyper voltage that is examined in this essay is lightning impact voltage. As to the atmospheric hyper voltages (lightning), it has been set as test voltage the shock 1.20/50 ms, because that was more or less the form in which the average rate of many recorded currents has concluded. The production of specific voltages took place at the double stage impact generator of the High Voltage laboratory, whose function is described in Chapter 2. An extra parameter that is examined during the study of dielectric persistence of insulating oils is the time that passes between the application of high enough to cause resolution in interspace voltage and resolution, which (time) is called time lag. In order to conduct the experiment, the above generator, oscillograph, hive of Plexiglass and Rogowski as well as poker planch electrodes were used. The tests took place under lightning impact voltages of positive polarity1.2/50 ms in Shell Diala Oil in order to study its behavior, as several factors on which it depends are altered. Counts were gathered in order to observe the impact of the size of interspace, oil strain, calmness time as well as atmospheric conditions on resolution voltage. As to the elaboration of counts, a program written on C programming language that effects the maximum probability method was used. Based on this method, we can draw precise rates on the voltage that corresponds with resolution possibility 50%, on typical deflection (σ) of the rates of resolution voltage for every set of counts as well as on the dispersion of V50 and σ. The results are presented on tables and diagrams of regular distribution. An extra factor examined is time lag for specific interspace lags regarding uniform as well as non uniform field.

Resumo: O presente estudo tem como objetivo avaliar parâmetros biomecânicos durante a saída de velocidade por meio da análise da força de reação do solo nas direções horizontal e vertical, o impulso resultante das forças de reação nas duas direções, o tempo de reação (agilidade) e a velocidade média em um determinado percurso em crianças praticantes e não praticantes de futebol de campo. A amostra foi constituída de 22 indivíduos com idades compreendidas entre 13 e 14 anos distribuídos em 2 grupos: G1, que foi considerado o grupo não praticante e G2, o grupo praticante de futebol de campo há mais de um ano. As medidas antropométricas utilizadas foram: a altura, o peso e o índice de massa corpórea (IMC). Os procedimentos estatísticos incluíram a média aritmética, o desvio padrão e o teste "t" de student com as duas amostras em par para média. Foi aceito um nível de significância de 5%. O programa estatístico utilizado foi o Biostat 4.0. Os resultados estatísticos demonstraram que o G2 obteve significativa relevância para a velocidade média no percurso em relação ao G1. Em contrapartida, para os demais parâmetros analisados, não apresentaram significância estatística. Conclusões: a) as plataformas desenvolvidas foram eficazes para a coleta de dados do estudo em questão; b) a velocidade média foi um parâmetro que apresentou significância estatística, como demonstrados nos estudos anteriores; c) os parâmetros de tempo de reação, força de reação horizontal e vertical e impulso resultante não apresentaram significância estatística, provavelmente pelo número pequeno da amostra e pela falta de um questionário específico para verificar se a criança é ativa ou não. Novas pesquisas deverão ser propostas para um posterior aperfeiçoamento dos resultados apresentados por esta pesquisa. / Abstract: This study aims to evaluate the biomechanical parameters during exit of speed by examining the strength of reaction soil in horizontal and vertical directions, the resulting movement of the forces of reaction in both directions, the time of reaction and average speed (agility), a route specializing in children practitioners and non-practitioners of soccer. The sample was composed of 22 individuals aged between 13 and 14 years divided into 2 groups: G1, who was considered the group not practitioners and G2, group of practitioners football field for over a year. The anthropometric measurements were used: the height, weight and body mass index (BMI). The statistical procedures included the arithmetic mean, standard deviation and the test "t" of student with the two samples in addition to average. It accepted a level of significance of 5%. The statistical program used was the Biostat 4.0. The statistical results showed that G2 received significant relevance for the average speed on the route on G1. In contrast, for all parameters analyzed, not statiscally significant. Conclusions: a) the developed platforms were effective for the collection of data from the study in question, b) the average speed was a parameter that presented statistical significance, as demonstrated in previous studies c) the parameters of the time of reaction , strength of reaction horizontal and vertical and impetus resulting, did not show statistical significance, probably by the small number of sample and the lack of a specific questionnaire to determine if the child is active or not. New research should be proposals for a further improvement of the results presented in this survey. / Orientador: Araildo Lima da Silva / Coorientador: José Geraldo Trani Brandão / Banca: Tamotsu Hirata / Banca: Luiz Alberto Batista / Mestre

Lightning is one of the main factors that cause Photovoltaic (PV) systems to fail. The PV modules inside PV systems, like any other electric equipment, will be degraded under electrical stress. The effect of electrical degradation of the PV modules caused by lightning induced voltage has been rarely reported. In the dissertation, the electrical properties degradation of a polycrystalline silicon module was studied. Firstly, lightning impulse voltages of positive polarity ranging from low to high are applied on different groups of the testing modules. All these lightning impulse voltage tests are conducted in the same experimental condition except for their stress voltage magnitudes. The maximum power output, I-V characteristics, and dark forward I-V curve are measured and reported periodically during the lightning impulse voltage tests. By comparing the maximum output power and changes in the internal electrical properties, it could be concluded that lightning impulse voltages, even medium voltage levels, will cause degradation to the sample. The relationship of the maximum output power and the number of applied impulses for different testing voltage levels are compared. An analysis of the electrical property changes caused by the lightning impulse voltages is presented. Secondly, a group of samples are tested with lightning impulse voltage of negative polarity. A comparison of the impulse voltage aging effects at the same voltage level with positive polarity is made. The maximum power output drop caused by positive and negative lightning impulses are compared. Laboratory results revealed that positive and negative lightning impulses will not only influence the degree of degradation, but also lead to different electrical property changes. Finally, a comparison of the effect of lightning impulses combined with other stress factors are discussed. The study simulates a field-aged sample’s behavior at lightning impulse voltage testing conditions. The result suggests that the degradation caused by lightning impulse voltage is greatly accelerated when the sample has bubbles and delamination. Electrical breakdown of the module is caused by the failure of the insulation.

No description available.

Self-control has been measured using a variety of methods including self-report measures, cognitive inhibition tasks, delay discounting and delay of gratification tasks, and persistence and willpower tasks. Although these are all theoretically linked to processes involved in self-control, recent evidence has shown that these diverse measurement techniques relate only minimally to one another. Assuming that self-control is a reflective construct, this would indicate that many of these tasks are poor indicators of self-control. The present research challenges the common assumption that self-control is a reflective construct and instead proposes that self-control is a formative construct. Conceptualizing of self-control as a formative construct could reconcile some of the inconsistencies in the literature, in particular the fact that many indicators for self-control do not correlate highly. To examine the possibility of a formative model of self-control, this research examines 13 commonly used measures of self-control and investigates indicator intercorrelations, indicator relationships with the theoretical consequences of self-control, and performs a vanishing tetrad test (Bollen & Ting, 2000). Results show that in general, indicator intercorrelations are low and nonsignificant as well as indictor correlations with theorized construct consequences. The results of the vanishing tetrad test suggest a reflective interpretation of self-control, but concerns with uniformly low covariances between indicators limit the interpretation of this test. It is concluded that currently available measures of self-control contain large sources of error variance and that questions about the ontological nature of the construct will be unanswerable until more precise measures are developed.

The purpose of this paper is to consider the impulse formulations of the Euler equations for incompressible and compressible fluids. Different gauges are considered. In particular, the Kuz'min gauge provides an interesting case as it allows the fluid impulse velocity to describe the evolution of material surface elements. This result affords interesting physical interpretations of the Kuz'min invariant. Some exact solutions in the impulse formulation are studied. Finally, generalizations to compressible fluids are considered as an extension of these results. The arrangement of the paper is as follows: in the first chapter we will give a brief explanation on the importance of the study of fluid impulse. In chapters two and three we will derive the Kuz'min, E & Liu, Maddocks & Pego and the Zero gauges for the evolution equation of the impulse density, as well as their properties. The first three of these gauges have been named after their authors. Chapter four will study two exact solutions in the impulse formulation. Physical interpretations are examined in chapter five. In chapter six, we will begin with the generalization to the compressible case for the Kuz'min gauge, based on Shivamoggi et al. (2007), and we will derive similar results for the remaining gauges. In Chapter seven we will examine physical interpretations for the compressible case.

<p>This dissertation explores the struggle between the impulse to cover up intimate violence and the impulse to make it public and consumable in nineteenth century England. It shows that intimate violence was both spectacular and unspeakable, rendering woman abuse a highly contested site of representation. It also reveals, however, that these ostensibly diametric modes of portraying violence worked in tandem to test the limits of what was socially and culturally representable during the period, and, in turn, to challenge hierarchies of genre, gender, class, and sexuality.</p> <p>This thesis is therefore both a study of the ways in which representations of intimate violence have avowed the imagined differences between members of disparate social categories and a study of how these differences often break down in the face of brutality. Chapter One shows that although street literature's representations of abuse seem invested in spectacularizing working-class violence, they often gesture towards the failures of middle-class domestic life and thus presume a unique vision of cross-class, shared moral experience. Chapter Two explores how feminist poet, pamphleteer, and novel writer Caroline Norton conflates multiple female identities to emphasize the importance of women's creative self-imagining as a means to resist physical violence and the rhetoric that encourages or allows it. Reading Anthony Trollope's Barchester Towers, Chapter Three intersects discourses on abuse with disability studies to interrogate how the conspicuous bodies of battered women can disrupt male homosocial interactions and complicate discourse on trauma and representation. Finally, Chapter Four considers the ways in which displacements of intimate violence in Wilkie Collins's The Woman In White create sympathetic bonds that blur subjective distinctions between abusive men and violated women to test male authority over representation.</p> / Thesis / Doctor of Philosophy (PhD)

Noise-induced hearing loss and tinnitus are the two most prevalent service-connected disabilities for veterans receiving compensation (Department of Veterans Affairs, 2010). While it is possible to protect against noise-induced hearing damage with hearing protection devices (HPDs) and hearing protection enhancement devices (HPEDs), military personnel resist using HPDs/HPEDs that compromise their situational awareness, including ability to localize enemy gunfire. Manufacturers of a new generation of "pass-through" level-dependent HPEDs claim these devices preserve normal or near-normal hearing. A research study was conducted to evaluate localization of suprathreshold gunshot's report (from blank ammunition) with one passive (3M's Single-Ended Combat Arms earplug) and three electronic level-dependent HPEDs (Peltor's Com-Tac II electronic earmuffs and Etymotic's EB 1 and EB 15 High-Fidelity Electronic BlastPLG earplugs), in comparison to the open ear in an in-field test environment with ambient outdoor noise and in 82 dBA diesel truck noise with nine normal and four impaired hearing participants. Statistical analysis showed worse localization accuracy and response time with the Com-Tac II earmuffs than with the other tested HPEDs. Performance with all HPEDs was worse than that with the open ear, except on right-left confusions, in which the Com-Tac II stood alone as worst, and in response time, for which the EB 1 earplug was equivalent to the open ear. There was no significant main effect of noise level. There was generally no significant effect of hearing ability. However, participants with impaired hearing had more right-left confusions than those with normal hearing. Subjective ratings related to localization generally corroborated objective localization performance. Three follow-up experiments were performed: (1) an assessment of the effect of microphone position on localization with the EB 15, which showed a limited advantage when the microphone was positioned near the opening of the ear canal compared to when it was facing outwards; (2) an assessment of Etymotic's QuickSIN test as a predictor localization performance, which showed little correlation with localization performance; and (3) an assessment of the acoustic properties of the experiment site, which was inconclusive with regards to the direction of dominant sound energy from gunshots from each of the shooter positions. / Ph. D.

Many methods and equations have been developed to predict bed load transport rates, most of which use some comparison between shear stress and critical shear stress. The critical shear stress is determined by the point of incipient motion. Researchers have attempted to predict bed load transport both deterministically with mean parameters and stochastically attempting to take into account the fluctuations of velocity at points near threshold. This work attempts to show that more than simple force balances are needed to determine the point at which a particle will move. Turbulent fluctuations in velocity seem to have an effect of particle entrainment. The fluctuations in velocity can be several times greater than their time averaged counterparts. These short durations of high velocity often result in particle movement even though the mean flow may be less than or very near critical conditions. Through experiments of a single spherical particle on a simple bed geometry in air without the effects of water, it is shown that time duration of force has an effect on entrainment. This shows that there may be a constant force-time combination, or impulse, required to entrain sediment. / Master of Science

Attention on impulsive buying behavior has been increased from both researchers and marketers, as the negative consumption experience resulting from this unplanned buying could harm the business severely in terms of brand building, reputation as well as a loss of customer. By reviewing previous literatures, we have identified that there is still little research about the post-consumer behavior of impulse purchases, namely on consumers’ regret triggered from what they have bought impulsively. The purpose of this study is to discover the triggers of buyer regret from impulse purchase, which is presented by the research question “What are the triggers of buyer regret from impulse purchases?” By conducting a quantitative research, we proposed a conceptual model of impulse purchase regret that consists of six hypotheses. The technical tool that we used to test the conceptual model is a SPSS extension called AMOS, whereas the analysis method uses the application of structural equation modeling. We collected our primary data (187 viable responses) via a questionnaire through convenience sampling. By testing all the data with AMOS, we received the following result: 5 hypotheses are accepted and 1 hypothesis is rejected. This result indicates that upwards counterfactual thinking (CFT) on forgone alternatives, a change in significance, and under consideration are positively related to impulse purchase regret; external stimuli and consumer susceptibility to interpersonal influence (CSII) have indirect influence on impulse purchase regret. By applying our theoretical background to analyze the result, we suggest that consumer’s rational buying thinking still plays an important role in post evaluation stage of impulse purchase, even though it disrupts the rational buying process in the beginning. Lastly, we believe that several parties could benefit from our research, they are marketing, academia as well as consumers.