A substantial literature has drawn inconsistent conclusions about bias in teachers’ perceptions of minority students and girls. Although the number of immigrant students in U.S. schools is increasing rapidly, research on teachers’ perceptions of foreign-born students is lacking. Using a nationally representative sample of U.S. high school students from the Educational Longitudinal Study of 2002, this work evaluates teachers’ perceptions of academic behavior by student nativity and ethnoracial identity. Net of objective criteria, teachers disproportionally perceive students as hardworking or passive in ways conforming to ethnic and immigrant stereotypes. These appraisals are highly subject-specific, racialized, and gendered. This work has important implications for the assimilation of immigrant students into the U.S. educational system. / text

Η παρούσα διπλωματική εργασία αποτελεί μια μελέτη επί του ελέγχου των κινητήρων επαγωγής που στόχο έχει τη διερεύνηση της επίδασης των διαφορετικών σημάτων ανάδρασης (ανάλογο στροφών και ανάλογο του τετραγώνου στοφών) στην απόκριση του συστήματος κίνησης. Για το σκοπό αυτό αναπτύχθηκε ενδελεχώς η σχετική θεωρία, μελετήθηκε η παθητικότητα ηλεκτρομηχανικών συστημάτων, χρησιμοποιήθηκε συγκεκριμένος ηλεκτρονικός μετατροπέας και κατασκευάστηκε μετατροπέας σήματος συνεχούς ρεύματος ανάλογος του αριθμού των στροφών και του τετραγώνου του. Στα πλαίσια της εργασίας εξετάστηκε PI έλεγχος βασισμένος στον βαθμωτό (Scalar V/f) έλεγχο, με σήμα αρνητικής ανάδρασης ρεύμα ανάλογο του αριθμού και του τετραγώνου του αριθμού των στροφών. Μελετήθηκε η απόκριση του κινητήρα και για τους δύο ελέγχους για διαφορετικές τιμές των παραμέτρων KP και KI, και διερευνήθηκε ποιες είναι αυτές ώστε να έχουμε βέλτιστη απόκριση. Συγκεκριμένα ποιες παρουσιάζουν την μικρότερη υπερύψωση, τον μικρότερο χρόνο αποκατάστασης, το μικρότερο σφάλμα μόνιμης κατάστασης. Επίσης εξετάστηκε η επίδραση της κάθε παραμέτρου στην διαμόρφωση της εσωτερικής ενέργειας του κινητήρα. / This diploma thesis forms a study on control techniques of induction motors which comes with the intention to explore the effets of different signals of feedback (proportional to the number of revolutions and to the square of the number of revolutions) on the output of the motor. For this purpose sedulous analysis of relevant theory was carried out, passivity of electromechanical systems was studied, a specific electronic commutator was used and a converter of constant current signal proportional to the number of revolutionsand to the square of the number of revolutions was developed. In this thesis a PI controller based on the Scalar V/f control with a signal of current of negative feedback was examined. The output of the motor for both the controls aid for different values of the parameters KP and KI was examined, and it was investigated which of them lead to an optimal output of the motor. It was studied more specifically which of them result in the optimal overshoot, settling time and the error of the permanent mode. Furthermore, it was inquired the impact of its parameter on the modulation of the intrinsic power of the motor.

Note: / as hip and knee prosthesis, orthopaedic fixations and coronary stents. The definition of a material's biocompatibility necessitates meeting a number of criteria, including high corrosion resistance and desirable interactions of the material's surface with biological species, such as cells, platelets, and serum proteins. SSs offer acceptable resistance to uniform (general) corrosion when used as materials of construction in sorne industrial applications, which is due to the formation of a thin passive oxide film on their surface. [...] / Les aciers inoxydables (AI) 316-L sont fréquemment utilisés dans le domaine biomédical. Par exemple, nous les retrouvons dans les prothèses de hanche et de genou, dans les fixatures orthopédiques et dans les prothèse vasculaires. Pour qu'un matériel soit biocompatible, il doit avoir une résistence élevée à la corrosion. De plus, la surface du matériel doit avoir des intéractions favorables avec les différentes espèces biologiques c'est-à-dire les cellules.[...]

Thesis (Ph. D.)--Ohio State University, 2005. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2006 Nov 29

Στην παρούσα διπλωματική εργασία εκπονείται μελέτη που αφορά την παθητικότητα και τον έλεγχο ηλεκτρομηχανικών συστημάτων. Δίνεται μεγαλύτερη βαρύτητα στον επαγωγικό κινητήρα και τους ελέγχους που μπορεί να εφαρμοστούν σε αυτόν. Η επαγωγική μηχανή χρησιμοποιείται σε μεγάλο εύρος εφαρμογών στο πεδίο μετατροπής της ηλεκτρικής ενέργειας σε μηχανικό έργο. Οι αιτίες για αυτήν την προτίμηση είναι πολλές. Μεταξύ αυτών συγκαταλέγονται το φτηνό κόστος και η εύκολη συντήρηση. Για πιο απαιτητικές εφαρμογές όμως η επαγωγική μηχανή απαιτεί πολύπλοκα συστήματα τροφοδοσίας και ελέγχου. Χρησιμοποιούνται πηγές τάσης (ή ρεύματος) βασισμένες σε τοπολογίες που περιλαμβάνουν διατάξεις με ηλεκτρονικά ισχύος όπως μετατροπείς ac/dc με IGBT διακοπτικά στοιχεία ισχύος. Ο έλεγχος επίσης μπορεί να βασίζεται είτε σε απλές βαθμωτές λογικές ή σε πιο προχωρημένα συστήματα σε λογικές διανυσματικού ελέγχου. Στις περιπτώσεις αυτές μπορούμε να επιτύχουμε εξαιρετικά λειτουργικά χαρακτηριστικά όπως ρύθμιση στροφών ή θέσης με υψηλή ακρίβεια αλλά με κόστος την πολυπλοκότητα στην δομή του συστήματος ισχύος και αυτομάτου ελέγχου. Στην παρούσα διπλωματική εργασία, αρχικά μελετάμε τη δυναμική συμπεριφορά τριφασικής ασύγχρονης μηχανής με χρήση του αναλυτικού μη γραμμικού μοντέλου της. Συγκεκριμένα, για την μελέτη της μεταβατικής συμπεριφοράς χρησιμοποιούμε το μετασχηματισμένο μοντέλο της μηχανής στο σύστημα κάθετων αξόνων d-q. Αυτό επιτυγχάνεται με την χρήση του μετασχηματισμού Park, στο τριφασικό αρχικό μοντέλο της μηχανής. Η επιλογή του συστήματος κάθετων αξόνων γίνεται στο στρεφόμενο με σύγχρονη ταχύτητα σύστημα αναφοράς. Στο σύστημα αυτό οι ημιτονοειδείς ποσότητες των μεταβλητών στην μόνιμη κατάσταση λειτουργίας μετατρέπονται σε συνεχείς (dc) μεταβλητές, πράγμα που διευκολύνει την ανάλυση και σχεδίαση του ελέγχου. Με στόχο την εφαρμογή απλών σχημάτων ελέγχου στην επαγωγική μηχανή που να μπορούν να οδηγούν σε λειτουργία υπό επιθυμητό αριθμό στροφών ανεξάρτητα προς το εμφανιζόμενο στην έξοδο μηχανικό φορτίο, χρησιμοποιούμε το μοντέλο αυτό στην ανάλυσή μας και αποδεικνύουμε ότι η επαγωγική μηχανή έχει την σημαντική ιδιότητα των Euler-Lagrange ηλεκτρομηχανικών συστημάτων, την παθητικότητα. Αυτό σημαίνει ότι μετά από κάποια διαταραχή, το σύστημά μας έχει απόσβεση τόσο στο ηλεκτρικό όσο και στο μηχανικό του μέρος. Επιπλέον, αποδεικνύεται ότι η ιδιότητα αυτή παραμένει ισχύουσα ανεξάρτητα με το όποιο σχήμα μη δυναμικού ελέγχου μπορούμε να εφαρμόσουμε. Έτσι, στην παρούσα διπλωματική εργασία εφαρμόζουμε απλούς PI ελεγκτές με σταθερά χρόνου πολύ μεγαλύτερη από αυτήν που εμφανίζει το αρχικό σύστημα, ούτως ώστε η δυναμική των PI ελεγκτών πρακτικά να μην εμπλέκεται με την δυναμική του συστήματος. Έτσι, το σύστημα παραμένει ουσιαστικά στην αρχική δυναμική του κατάσταση με την ιδιότητα της παθητικότητας ισχύουσα για τον προτεινόμενο έλεγχο που από την πλευρά της μηχανής φαίνεται πρακτικά στατικός. Εν συνεχεία, προσομοιώνουμε το σύστημα και επιβεβαιώνουμε ότι οι προτεινόμενοι απλοί PI ελεγκτές μπορούν να οδηγήσουν το σύστημα στην επιθυμητή κατάσταση λειτουργίας με επιθυμητό αριθμό στροφών. / This diploma thesis forms a study on passivity and control of electromechanical systems. We focus on induction machine and the methods we use to control it. Induction machine is used in a large range of applications especially in the field of energy conversion to mechanical work. There are many causes for this preference such as low cost and easy to preserve. For more demanding applications induction machine needs complicated supply sources and control systems. Voltage (or current) sources are used based on power electronics such as ac/dc converters with IGBT switching elements. The control used can be scalar in simple applications or vector control in advanced applications. By using vector control, we can achieve exceptional operational characteristics on velocity or position regulation with high precision but with huge complexity in the structure of the power system and the automatic control scheme. In this thesis, at first we study the dynamic performance of the 3-phase induction machine by using the precise non-linear model. Specifically. we use the transformed model of the induction machine on the dq axes system to study its dynamical performance. This can be achieved by using Park transformation on the initial 3-phase model of the machine. The choice we make on the dq axis is based on the synchronously rotating reference frame. In this system the sinusoidal quantities of the variables in steady state are converted to dc, helping us on the analysis and the design of the control. Our goal is the application of simple control shapes on the induction machine that can drive our system to the desirable velocity regardless the output of the mechanical load. To this end, in our analysis we first prove that the induction machine has the significant property of passivity, a fundamental property of Euler-Lagrange systems. This means that after a disturbance, our system has damping in both the mechanical and the electrical part. Moreover, it is proved that passivity is maintained regardless from the form of any non dynamic control scheme we may apply. So, in this thesis we use simple PI controllers with large time constant in order to avoid any influence between the dynamics of the PI controllers and the dynamic of our system. So the system maintains its initial dynamic property of passivity under the control we use. Afterwards, we simulate the system and we confirm that the PI controllers we use can drive the system to the desirable operational mode.

Este estudo avaliou próteses implantossuportadas obtidas por 2 técnicas (cilindro cimentado ou soldado a laser) e seus comportamentos no que tange à passividade e afrouxamento de parafusos. Foram confeccionadas PPFs de 3 elementos sobre 2 implantes: G1, técnica do cilindro cimentado; G2, técnica do cilindro soldado a laser (n=10). Avaliados níveis de desajuste vertical e passividade antes e após aplicação de cerâmica prensada e após ciclagem mecânica, e a perda de torque inicial dos parafusos de retenção protética antes e após fadiga. Ciclagem mecânica simulando 1 ano de função mastigatória normal (50N, 300.000 ciclos). Análises de desajuste vertical e passividade realizadas pelo método de Sheffield. Calculada % de perda de torque de inserção. Os dados de desajuste e perda de torque foram comparados estatisticamente pelo Modelo Linear de Efeitos Mistos. De modo geral, G1 apresentou níveis de desajuste vertical estatisticamente inferiores a G2 (p<0,05) nas três condições analisadas pelo teste de Sheffield, tanto antes quanto após ciclagem mecânica, atingindo valores máximos de desajuste correspondentes a: 11,94 ± 3,17&mu;m (G1) e 48,63 ± 39,68 &mu;m (G2), antes da ciclagem, 12,42 ± 6,19&mu;m (G1) e 47,62 ± 35,16&mu;m (G2), após a ciclagem, estando os parafusos parafusados. Adicionalmente, em todas as condições experimentais, a ciclagem mecânica não influenciou no desajuste de ambos os grupos (p<0,05), com exceção do molar em G1 quando analisado apertado (p<0,0001). Quando analisado G2, verificamos aumento estatisticamente significante do desajuste vertical após prensagem cerâmica para todos os elementos (p<0,0001) nos diferentes momentos avaliados, com exceção do molar quando avaliado solto, o qual apresentou desajustes semelhantes antes e após prensagem (p=0,052). Na análise de perda de torque, valores expressos em % de perda são apresentados: Pré-molar - G1- antes ciclagem: 31,04 ± 13,22%; G2- antes ciclagem: 33,97 ± 13,41% (G1 x G2 antes ciclagem: p=0,662); G1- após ciclagem: 42,36 ± 14,99%; G2- após ciclagem: 37,92 ± 9,32% (G1 x G2 após ciclagem: p=0,461). Quando analisado o pré-molar, não foram verificadas diferenças estatísticas antes e após ciclagem mecânica para ambos os grupos (G1: p=0,067; G2: p=0,423); Molar - G1- antes ciclagem: 30,77 ± 12,37%; G2- antes ciclagem: 44,37 ± 11,14% (G1 x G2 antes ciclagem: p=0,032); G1- após ciclagem: 39,28 ± 13,96%; G2- após ciclagem: 54,40 ± 26,39% (G1 x G2 após ciclagem: p=0,189). Quando analisado o molar, diferenças estatísticas também não foram identificadas antes e após ciclagem, para ambos os grupos (G1: p=0,392; G2: p=0,233). Diante dos resultados, é possível concluir que: G1 apresentou índices de desajuste vertical e passividade menores que G2, porém para ambos os grupos os desajustes estão dentro dos padrões aceitáveis pela literatura; ciclagem mecânica não promoveu alterações nos níveis de desajuste vertical e perda de torque (%) para ambos os grupos; ambas as técnicas não foram capazes de promover passividade absoluta, tendo em vista os maiores valores de desadaptação do lado solto quando comparados ao lado parafusado. / This study evaluated implant supported prostheses obtained by two techniques (cemented cylinder or laser welded cylinder) and their behavior regarding passivity and screw loosening. Three-element FPPs were made over 2 implants: G1, cemented cylinder technique, G2, laser welded cylinder technique (n=10). The levels of vertical misfit and passivity were evaluated before and after ceramic pressing, and after mechanical cycling; while loss of initial torque of prosthetic retaining screws, before and after mechanical cycling. The mechanical cycling simulated one year of normal masticatory function (50N, 300,000 cycles). Vertical misfit and passivity were analyzed by Sheffield\'s test. The percentage of torque loss was calculated. The misfit and torque loss data were statistically compared by Mixed Linear Model . Overall, G1 showed vertical misfit statistically lower than G2 (p<0.05) in the three conditions analyzed by Sheffield\'s test, before and after mechanical cycling, reaching maximum values of misfit corresponding to: 11.94 ± 3.17&mu;m (G1) and 48.63 ± 39.68 &mu;m (G2) before cycling; 12.42 ± 6.19&mu;m (G1) and 47.62 ± 35.16&mu;m (G2), after cycling, when screws were tightened. Additionally, in all experimental conditions, the mechanical cycling did not influence the misfit in both groups (p<0.05), except for the molar G1 when analyzed in the tightened condition (p<0.0001). When was analyzed G2, statistically significant increase in the vertical misfit was found after ceramic pressing for all elements (p<0.0001) for different moments, except when the molar was not tightened, which showed similar misfit before and after pressing (p=0.052). In the analysis of torque loss, values expressed as percentage of loss are presented: Pre-molar - G1- before cycling: 31.04 ± 13.22%, G2- before cycling: 33.97 ± 13.41% (G1 x G2 before cycling: p=0.662), G1- after cycling: 42.36 ± 14.99%, G2- after cycling: 37.92 ± 9.32% (G1 x G2 after cycling: p=0.461). When the pre-molar was analyzed, statistical differences before and after cycling were not found for both groups (G1: p=0.067; G2: p=0.423); Molar - G1- before cycling: 30.77 ± 12.37%; G2- before cycling: 44.37 ± 11.14% (G1 x G2 before cycling: p=0.032); G1- after cycling: 39.28 ± 13.96%; G2- after cycling: 54.40 ± 26 , 39% (G1 x G2 after cycling: p=0.189). When the molar was analyzed, statistical differences were not found before and after cycling for both groups (G1: p=0.392; G2: p=0.233). Based on these results, it is possible to conclude that: G1 showed vertical misfit and passivity smaller than G2, but for both groups, the misfits are within acceptable standards for the literature; mechanical cycling did not change the vertical misfit and torque loss (%) for both groups; both techniques were not able to promote absolute passivity, in view of the higher values of misfit when compared to the side no tightened.

In this thesis I explore the roles of silence in Virginia Woolf’s last novel, Between the Acts (1941). I focus on three readings of silence in the text. First, I consider her portrayal of malicious silences as unsaid judgments and aggressions and their impact on interpersonal relationships and interactions. Second, I look at detached, empty silence and its relation to the critical passivity Woolf noted in her audience in the early years of WWII. Finally, I consider silence as feminist resistance to traditional narratives through the intertwined experiences of Isa and Miss La Trobe.

O presente estudo pretende oferecer uma interpretação da reflexão moral de Montaigne que se opõe àquelas que a vêem centrada na alegação da passividade do ensaísta, reduzindo-a à prescrição de uma subordinação pragmática às leis e aos costumes e fazendo dos Ensaios uma mera descrição da condição humana. Através da leitura daqueles ensaios em que Montaigne mais parece passivo (nos quais tais interpretações justamente apóiam suas hipóteses), acreditamos encontrar os modos de operação de uma ação discreta, pautada pela exigência de adequação aos objetos e às circunstâncias, uma ação que abre espaço para o livre jogo das paixões segundo a conveniência. Espera-se, com isso, resgatar a dimensão normativa dos Ensaios, seja lançando luz sobre as preocupações permanentes do autor com a própria liberdade (sempre ameaçada pelo risco da servidão aos afetos), seja chamando a atenção dos leitores para o Montaigne político, atento aos riscos que a ambição, as inovações e os remédios extremos (a perfídia) trazem para ordem pública e, ao mesmo tempo, ocupado em sugerir (através do exemplo de seus mandatos à frente da mairie de Bordeaux) parâmetros para uma ação política discreta. / The present study has the purpose of responding to the commentators who interpret Michel de Montaignes thought under the key of passivity and see a complete absence of an ethics on the essays and reduce all montaigniana morality to a pragmatic subordination to the laws and costumes, and also seeing the Essays as a mere description of the human condition. Reading the essays in which Montaignes passivity seems attain his higher level (where such commentaries exactly base their hypotheses on) we sought to find the operating ways of a discreet action, ruled by that the objects and their circumstances impose; an action in which passions are gladly admitted only when it is convenient. We expect here to recover the Essays normative dimension, be it through shedding light on the authors permanent concern with his own freedom (always threatened by the risk of the servitude to affections), be it drawing the readers attention to the politician Montaigne, aware of the risks that ambition, innovations and grievous remedies (the perfidy) bring to the public order and, at the same time, able to suggest (through the example of his mandates ahead of mairie de Bordeaux) some patterns for a discreet political action.

This investigation determined that severe corrosion of steel can occur in the submerged portions of reinforced concrete structures in marine environments. Field studies of decommissioned pilings from actual bridges revealed multiple instances of strong corrosion localization, showing appreciable local loss of steel cross-section. Quantitative understanding of the phenomenon and its causes was developed and articulated in the form of a predictive model. The predictive model output was consistent with both the corrosion rate estimates and the extent of corrosion localization observed in the field observations. The most likely explanation for the observed phenomena that emerged from the understanding and modeling is that cathodic reaction rates under oxygen diffusional limitation that are negligible in cases of uniform corrosion can nevertheless support substantial corrosion rates if the corrosion becomes localized. A dynamic evolution form of the model was created based on the proposition that much of the steel in the submerged concrete zone remained in the passive condition given cathodic prevention that resulted from favorable macrocell coupling with regions of the steel that had experienced corrosion first. The model output also matched observations from the field, supporting the plausibility of the proposed scenario. The modeling also projected that corrosion in the submerged zone could be virtually eliminated via the use of sacrificial anode cathodic protection; the rate of corrosion damage progression in the low elevation zone above water could also be significantly reduced. Continuation work should be conducted to define an alternative to the prevalent limit-state i.e., visible external cracks and spalls, for submerged reinforced concrete structures. Work should also be conducted to determine the possible structural consequences of this form of corrosion and to assess the technical feasibility and cost/benefit aspects of incorporating protective anodes in new pile construction.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work has as purpose, from the thought of Michel Henry, contemporary French philosopher, afford a study on the phenomenology of affectivity, more specifically on henrianas investigations regarding affectivity, considering the essential notes investigated and formulated in relation life, phenomenology, in the case the Phenomenology of Life or Material Phenomenology, and passivity. The intended reflection aims to consider possibilities that arise for the contemporary phenomenological field. The main thesis to be defended and grounded is that the essence of phenomenology of life manifests itself in immanent way by means of the affectivity. It is investigating the foundations for a Phenomenology of Affectivity, thus presenting a conceptualization from the radical immanence of life. Affectivity, privileged subject in Henry's works, is reached or reaches a very special way the experience of radical subjectivity, which, according to our philosopher, the life essentializes up itself, affecting itself in the experience of self same, the radical immanence of his affectivity. Because the concrete truth of this movement is the life that proves herself. Which is realized in his pathos, in the subjectivity that is known, independent of any conceptual or sensitive approach, or of a intentional look, but life in the absolute probation of their intrinsic certainty, in a material meaning, in the materiality of his pure appear that gives us access to itself, made in the modalities of suffering and enjoy, in the revelation itself, in its pathos of passivity that is affected. In order to sustain the structure of his thought, which culminates in the formulation of the phenomenology of life, Henry's concern aims to open up new fields of inquiry about the effective fenomenalização the phenomenality as such and in the reversal of phenomenology, a rethinking on this, another direction, a material bias. Therefore, this work is based in the works of this philosopher, in particular L'Essence de la manifestation. / A presente dissertação tem por intuito, a partir do pensamento de Michel Henry filosófo contemporâneo francês, proporcionar um estudo acerca da fenomenologia da afetividade, mais especificamente sobre as investigações henrianas a respeito da afetividade, levando em consideração os apontamentos essenciais averiguados e formulados em relação à vida, fenomenologia, no caso a Fenomenologia da Vida ou Fenomenologia Material e passividade. A reflexão pretendida objetiva considerar possibilidades que surgem para o campo fenomenológico contemporâneo, a tese principal a ser defendida e fundamentada é: que a essência da fenomenologia da vida se manifesta de forma imanente por meio da afetividade. Trata-se de investigar os fundamentos para uma Fenomenologia da Afetividade, apresentando assim, uma conceituação a partir da imanência radical da vida. A afetividade, assunto privilegiado nas obras de Henry, é atingida ou atinge de modo muito especial à experiência da subjetividade radical, a qual conforme o nosso filósofo a vida essencifica em si mesma, se autoafetando, na experiência de si mesma, na imanência radical de sua afetividade. Pois a verdade concreta desse movimento é a vida que se prova a si mesma. A qual se realiza em seu pathos, na subjetividade que se conhece independente de qualquer abordagem conceptual ou sensível, ou de um olhar intencional, mas a vida na provação absoluta de sua certeza intrínseca, em uma significação material, na materialidade de seu puro aparecer que nos dá acesso a si mesma, que se constitui nas modalidades do sofrer e do fruir, na revelação de si, no seu pathos da passividade que é afetada. A fim de sustentar a estrutura de seu pensamento, que culmina na formulação da fenomenologia da vida, a preocupação de Henry mira-se a abrir novos campos de investigação acerca da fenomenalização efetiva da fenomenalidade enquanto tal e na reversão da fenomenologia, um repensar esta, um outro direcionamento, um viés material. Para tanto este trabalho tem como base as obras deste filósofo, em especial, a L Essence de la manifestation.