Este trabalho apresenta um novo modelo de análise de falha em estruturas metal-polímero que, além de considerar a falha independente no metal ou no polímero, leva em consideração a falha na região de interface metal-polímero em decorrência de desgaste por deslizamento, quando existe movimento relativo entre as superfícies. Inicialmente, o estudo apresenta as principais características dos metais e polímeros e os mecanismos de falha mais relevantes. Faz a proposta do modelo de análise de falha e por último, apresenta a análise completa de falha de enrijecedores à flexão, uma estrutura metal-polímero utilizada pela indústria de óleo e gás. O modelo proposto permite fazer a previsão da taxa de desgaste de polímeros por deslizamento em função do ângulo da aspereza da superfície metálica, em situações onde a falha é gerada por fadiga de alto ciclo. / This work presents a new model for evaluating the failure in polymer-metal structures that, besides considering the isolated failure in metal or polymer, considers the failure in the polymer-metal interface region due to sliding wear, when there is relative movement between the surfaces. Initially, the study presents the main characteristics of metals and polymers and the most relevant failure mechanisms. Makes the proposed failure analysis model and, finally, shows the complete analysis of failure in bending stiffeners, a polymer-metal structure used by the oil and gas industry. The proposed model allows the prediction of the wear rate of polymers by sliding a function of asperity´s angle of the metal surface in situations where failure is generated by high cycle fatigue.

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Este trabalho apresenta um novo modelo de análise de falha em estruturas metal-polímero que, além de considerar a falha independente no metal ou no polímero, leva em consideração a falha na região de interface metal-polímero em decorrência de desgaste por deslizamento, quando existe movimento relativo entre as superfícies. Inicialmente, o estudo apresenta as principais características dos metais e polímeros e os mecanismos de falha mais relevantes. Faz a proposta do modelo de análise de falha e por último, apresenta a análise completa de falha de enrijecedores à flexão, uma estrutura metal-polímero utilizada pela indústria de óleo e gás. O modelo proposto permite fazer a previsão da taxa de desgaste de polímeros por deslizamento em função do ângulo da aspereza da superfície metálica, em situações onde a falha é gerada por fadiga de alto ciclo. / This work presents a new model for evaluating the failure in polymer-metal structures that, besides considering the isolated failure in metal or polymer, considers the failure in the polymer-metal interface region due to sliding wear, when there is relative movement between the surfaces. Initially, the study presents the main characteristics of metals and polymers and the most relevant failure mechanisms. Makes the proposed failure analysis model and, finally, shows the complete analysis of failure in bending stiffeners, a polymer-metal structure used by the oil and gas industry. The proposed model allows the prediction of the wear rate of polymers by sliding a function of asperity´s angle of the metal surface in situations where failure is generated by high cycle fatigue.

We study the dynamics of an elastic fiber in a viscoelastic fluid driven by a four-roll mill. The viscoelasticity is modeled by the FENE-P model and the coupling between the fiber and the fluid is resolved by the immersed boundary method. Numerically, we follow Peskin's formally second order method to solve the fiber-fluid equations and square root method to solve the viscoelasticity equations. We examine the effect of Weissenberg number (Wi) and fiber rigidity on fiber motion and the evolution of polymer stress. We also investigate the ability of the fiber to escape closed streamlines in Newtonian fluids and viscoelastic fluids. We find that large polymer stresses occur near the ends of the fiber when it is compressed. In addition, we find that viscoelasticity hinders a fiber's ability to traverse multiple cells in the domain. / 1 / Qiang Yang

In recent years, in order to promote the MOSFET¡¦s frequency and performance, the dimension keeping scale down, we can get more transistors in the same area. But nowadays the development of the lithography technology has come to the bottleneck, we must find the other way to improve the performance of transistor. In this study, the strained silicon effect and reliability of CMOS are fully discussed. In order to get strain from the channel, by process, deposit Si3N4 at NMOS and adopt the silicon-germanium epitaxy on source/drain by PMOS, can effective improve NMOS and PMOS electronic characteristic. Besides, silicon substrate is bent by applying external mechanical stress, the lattice of channel will have strain due to uniaxial tensile stress by NMOS and strain due to uniaxial compressive stress by PMOS. By these ways, we successfully improve drain current and mobility of NMOS and PMOS. Furthermore, this study is also probing into strain silicon at low temperature, the impacts on electronic characteristic by different scattering mechanism.

Slavoj Zizek is a contemporary political philosopher widely recognized for his aphoristic style. Contrary to many forms of more traditional theory, Zizek does not forward his arguments as a series of well-argued, logically flowing propositions, but rather as a cacophony of diagnoses running the gamut of social science and culture studies while nevertheless always slipping from one position to another, occupying at times the position of the orthodox Marxist in the face of post-modernism’s excesses, and at other times doing quite the opposite. This study proposes a reading methodology that takes aphorism and hyperbole as key elements of writing; more specifically, this study understands writing as a political intervention, and reads Zizek’s recent works in this light. Arguing that Zizek occupies a multitude of positions against a multitude of interlocutors on the post-Marxist scene, this thesis claims that it is precisely his ability to navigate between two distinct scenes which constitutes his novelty. Zizek combats conventional forms of leftism in order to open up a space for a new theoretical position, denying the coordinates of both post-Marxism and postmodernism.

Slavoj Zizek is a contemporary political philosopher widely recognized for his aphoristic style. Contrary to many forms of more traditional theory, Zizek does not forward his arguments as a series of well-argued, logically flowing propositions, but rather as a cacophony of diagnoses running the gamut of social science and culture studies while nevertheless always slipping from one position to another, occupying at times the position of the orthodox Marxist in the face of post-modernism’s excesses, and at other times doing quite the opposite. This study proposes a reading methodology that takes aphorism and hyperbole as key elements of writing; more specifically, this study understands writing as a political intervention, and reads Zizek’s recent works in this light. Arguing that Zizek occupies a multitude of positions against a multitude of interlocutors on the post-Marxist scene, this thesis claims that it is precisely his ability to navigate between two distinct scenes which constitutes his novelty. Zizek combats conventional forms of leftism in order to open up a space for a new theoretical position, denying the coordinates of both post-Marxism and postmodernism.

Diamidines are compounds with antiparasitic properties that target the minor groove of DNA. The mechanism of action of these compounds is unknown, but topological changes to DNA structure are a possibility. In this study, we have developed a polyacrylamide gel based screening method to determine topological effects of diamidines on four target sequences: AAAAA, TTTAA, AAATT, and ATATA. The changes caused are sequence dependent, but generally the effect on AAAAA and AAATT is the same while the effect on TTTAA and ATATA is the same. A few compounds show interesting sequence dependent topological effects in the polyacrylamide screening method that could be caused by the compound forming a dimer. Mass spectrometry is used to determine the stoichiometry of DNA-compound complexes. Once compounds show topological effects in the screening method, a bent fragment of kinetoplast DNA is isolated to determine if the same effects occur with DNA from a parasite.

This thesis investigates the characteristics of an involute gear system including contact stresses, bending stresses, and the transmission errors of gears in mesh. Gearing is one of the most critical components in mechanical power transmission systems. Transmission error is considered to be one of the main contributors to noise and vibration in a gear set. Transmission error measurement has become popular as an area of research on gears and is possible method for quality control. To estimate transmission error in a gear system, the characteristics of involute spur gears were analyzed by using the finite element method. The contact stresses were examined using 2-D FEM models. The bending stresses in the tooth root were examined using a 3-D FEM model. Current methods of calculating gear contact stresses use Hertzs equations, which were originally derived for contact between two cylinders. To enable the investigation of contact problems with FEM, the stiffness relationship between the two contact areas is usually established through a spring placed between the two contacting areas. This can be achieved by inserting a contact element placed in between the two areas where contact occurs. The results of the two dimensional FEM analyses from ANSYS are presented. These stresses were compared with the theoretical values. Both results agree very well. This indicates that the FEM model is accurate. This thesis also considers the variations of the whole gear body stiffness arising from the gear body rotation due to bending deflection, shearing displacement and contact deformation. Many different positions within the meshing cycle were investigated.

This thesis investigates the characteristics of an involute gear system including contact stresses, bending stresses, and the transmission errors of gears in mesh. Gearing is one of the most critical components in mechanical power transmission systems. Transmission error is considered to be one of the main contributors to noise and vibration in a gear set. Transmission error measurement has become popular as an area of research on gears and is possible method for quality control. To estimate transmission error in a gear system, the characteristics of involute spur gears were analyzed by using the finite element method. The contact stresses were examined using 2-D FEM models. The bending stresses in the tooth root were examined using a 3-D FEM model. Current methods of calculating gear contact stresses use Hertzs equations, which were originally derived for contact between two cylinders. To enable the investigation of contact problems with FEM, the stiffness relationship between the two contact areas is usually established through a spring placed between the two contacting areas. This can be achieved by inserting a contact element placed in between the two areas where contact occurs. The results of the two dimensional FEM analyses from ANSYS are presented. These stresses were compared with the theoretical values. Both results agree very well. This indicates that the FEM model is accurate. This thesis also considers the variations of the whole gear body stiffness arising from the gear body rotation due to bending deflection, shearing displacement and contact deformation. Many different positions within the meshing cycle were investigated.