Dissertations / Theses on the topic 'Anti-symmetric'

Neste trabalho, fazemos um estudo dos campos tensoriais antissimétricos em geral e, em particular, do campo tensorial antissimétrico de ordem dois. Utilizando o método de quantização BRST-BFV para teorias redutíveis no formalismo hamiltoniano, mostramos a equivalência quântica do campo tensorial antissimétrico de ordem dois não-massivo ao campo escalar em 4 dimensões e ao campo vetorial no gauge de Lorentz em 5 dimensões. Também é mostrada a equivalência entre as formulações de 1ª e 2ª ordem do campo tensorial antissimétrico de ordem dois. Por fim, é efetuada a quantização BRST-BFV de um modelo de partícula relativística com spin com duas supersimetrias acrescido de um termo Chern-Simons, mostrando que a amplitude de transição obtida equivale à amplitude de transição do \"rotacional\" de um campo tensorial antissimétrico de ordem qualquer. O caso massivo também é tratado brevemente.<br>In this work, we make a study of anti symmetric tensor fields in general, and, in particular, of the anti symmetric tensor fields of order two. Using the BRST-BFV quantization method for reducible theories in the Hamiltonian formalism, we show the quantum equivalence of the massless anti symmetric tensor field of order two to the scalar field in 4 dimensions, and to the vector field in the Lorentz gauge in 5 dimensions. It is also shown the quantum equivalence between the 1st and 2nd order formulations for the anti symmetric tensor field of order two. Finally, it is made the BRST-BFV quantization of a model of relativistic spinning particle with two super symmetries with a Chern-Simons term, showing that the transition amplitude obtained is equivalent to the transition amplitude for the field strength of an anti symmetric tensor field of any order. The massive case is also treated in breaf.

Sejam $F$ um corpo de característica diferente de $2$ e $G$ um grupo. A partir da involução clássica, que envia cada elemento em seu inverso, e uma orientação do grupo $G$ é possível definir uma involução clássica orientada na álgebra de grupo $FG$. O objetivo desta tese é estudar propriedades de Lie do conjunto dos elementos simétricos $(FG)^+$ e, em alguns casos, do conjunto dos elementos anti-simétricos $(FG)^-$. Primeiro, abordamos o caso quando $G$ não tem elementos de ordem $2$. Aqui, mostramos que se $(FG)^+$ (ou $(FG)^-$) é Lie nilpotente ou Lie $n$-Engel, então $FG$ também é Lie nilpotente ou Lie $m$-Engel, respectivamente. Depois, consideramos o caso quando $G$ contém uma cópia do grupo quatérnio de ordem $8$. Neste caso, caracterizamos completamente as álgebras de grupo tais que $(FG)^+$ é fortemente Lie nilpotente, Lie nilpotente e Lie $n$-Engel. Como consequência, provamos que o conjunto das unidades simétricas deste tipo de grupos é nilpotente. Estudamos também o caso em que quando $G$ não contém uma cópia do grupo quatérnio de ordem $8$. Em particular, apresentamos um exemplo que mostra que os resultados obtidos em pesquisas anteriores, com a involução clássica, não devem ser esperados ao trabalhar com involuções clássicas orientadas. Não entanto, damos alguns casos especiais de grupos nos quais esses resultados são obtidos. Finalmente, estudamos o índice de Lie nilpotência de $(FG)^+$. Estabelecemos uma condição necessária e suficiente, para que o índice de Lie nilpotência de $(FG)^+$ e a classe de nilpotência das unidades simétricas de uma álgebra de grupo Lie nilpotente sejam o maior possível. Além disso, consideramos a situação em que o grupo $G$ contém uma cópia de $Q_8$.<br>Let $F$ be a field of characteristic different from $2$ and $G$ a group. From the classical involution, which sends each element in its inverse and an orientation of $G$, it is possible to define an oriented classical involution on the group algebra $FG$. The goal of this thesis is to study Lie properties of the set of symmetric elements $(FG)^+$ and, in some cases, of the set of skew-symmetric elements $(FG)^-$. We first deal with the case when $G$ does not have elements of order $2$. In this situation, we show that if $(FG)^+$ (or $(FG)^-$) is Lie nilpotent or Lie $n$-Engel, then the whole group algebra $FG$ satisfies the same property. Later we consider the case when $G$ contains a copy of the quaternion group of order $8$. In this instance, we give a complete description of the group algebras such that $(FG)^+$ is strongly Lie nilpotent, Lie nilpotent and Lie $n$-Engel. As a consequence, we get that the set of symmetric units of this kind of groups is nilpotent. Furthermore, we study the case when $G$ does not contain a copy of the quaternion group of order $8$. Here, we present an example that shows that the previews results obtained in former works, with the classical involution, may not hold with an oriented classical involution. However, we give some kinds of groups for which those results are achieved. Finally, we study the Lie nilpotency index of $(FG)^+$. It is given a necessary and sufficient condition to the Lie nilpotency index of $(FG)^+$ and the nilpotency class of the symmetric units to be maximal, in a Lie nilpotent group algebra. In addition, we consider the situation when $G$ contains a copy of the quaternion group of order $8$.

Thesis (Ph. D.)--Ohio State University, 2005.<br>Title from first page of PDF file. Document formatted into pages; contains xi, 196 p.; also includes graphics. Includes bibliographical references (p. 195-196). Available online via OhioLINK's ETD Center

碩士<br>國立交通大學<br>機械工程學系<br>100<br>This thesis develops a new acoustic wave transducer constructed from the anti-symmetric interdigitated electrode piezoelectric fiber composite (APFC). It can be used as a key component to generate fixed-wavelength flexural plate waves for ultrasonic inspection and structural health monitoring applications. The APFC is formed with unidirectional piezoelectric fibers sandwiched between two thin flexible sheets printed with interdigitated electrodes (IDE). The electric field lines induced by anti-symmetrically aligned electrodes are inclined to the piezoelectric fibers. The IDE provides necessary electric field for polling and excitation of flexural plate waves. Because of light mass and moderate flexibility, APFC is ideally conformable to the curved surface of the host structures. The numerical simulation for understanding the dynamic characteristics of APFC was carried out using finite element analysis. The frequency responses of APFC are explored as a function of the electrode pitch. This study also successfully fabricated prototype APFC, and the performance tests were conducted. The operating frequency of APFC is relevant to the electrode pitch as well as the material properties and thickness of the host structures. The flexural resonances of APFC still remain when it is adhered to an aluminum host plate. The acoustic field induced by APFC has high directivity and small energy dissipation. The amplitude linearly decreases with increasing travel distance. The similar attenuation characteristics can be found in the APFC with different electrode pitches.

碩士<br>國立交通大學<br>機械工程系<br>91<br>The anti-control and synchronization of chaos for a two-degree-of —freedom heavy symmetric gyroscope system are studied in this thesis. Because of the nonlinear terms of the system, the system exhibits both regular and chaotic motions. By applying numerical results, Lyapunov exponent, bifurcation diagram, phase diagram, time history are used to observe periodic and chaotic motions. Four chaos anti-control methods are applied for the system, such as adding a constant term, adding a periodic square wave term, adding a periodic saw tooth wave term and adding a periodic triangle wave term. It is found that each anti-control method can effectively increase the range of chaotic motion. Then coupled terms and linearization of error dynamics are used to accomplish the chaotic synchronization between two different order systems. Finally, by Lyapunov stability theory with control terms, and by random optimization method, the synchronization of two identical systems and tracking of the parameter of the systems are studied.

碩士<br>國立中央大學<br>能源工程研究所<br>106<br>polycrystalline zinc oxide has a high resistance value, so generally, in the application of a transparent conductive film, it is doped with Ш elements (boron, aluminum, gallium, indium, etc.) to improve its conductivity and also improve its conductivity. Increase its high temperature stability.However, Single crystal zinc oxide (ZnO) is an N-type II-VI wide band gap semiconductor material with high transmittance in the visible range. It has similar properties to GaN and exciton binding energy is higher than GaN. Substituting GaN has become a material for UV LDs and LEDs . In this study, the thermal field, flow field and species transfer simulation of MOCVD near-coupled spray-type anti-symmetric cavity were studied. At first, according to the chemical reaction formula of the grown ZnO thin film, a surface adsorption model was established to compare the effects of different adsorbed species and chemical reaction formulas on the growth efficiency of ZnO thin films. Ten gas phase chemical reaction schemes were simplified into three main chemical reaction formulas. In the design of the cavity, the transparent conductive film is considered to be square. Therefore, a square reaction cavity is designed for the square film, and the large glass carrier is difficult to rotate, and the effect of uniform deposition of the species is achieved by opposing the staggered inlet holes. At the same time, the effect of changing process parameters on surface adsorption efficiency and film uniformity is discussed. The growth efficiency of ZnO thin film increases with the increase of process pressure. The growth rate increases with temperature and the slope increases with pressure. In addition, ZnO thin film growth efficiency, growth rate with pressure change When the process temperature increases, the slope increases; the flow rate increases, the growth efficiency of ZnO thin film increases, but the flow rate reaches a certain multiple does not increase the long rate; the inlet pore size increases, and the growth efficiency will increase, but the aperture reaches a certain value does not improve the growth efficiency. In this study, the parameters of the three venting radii within the set range are scanned to achieve the minimum error of the ZnO film uniformity. The simulation result is 20mm above the hole. The lowest uniformity error of the upper uniform hole 20mm, the middle suction hole 35mm and the lower suction hole 25mm will have the lowest uniformity error of 0.0802%.

博士<br>國立交通大學<br>電信工程系<br>90<br>The thesis mainly consists of three parts. In the first part, the author proposes a circuit-modeling perspective of leaky-mode leakages in a corner-fed square patch. The second part demonstrates a periodic microstrip radial antenna array with a conical beam. The radiation mechanisms of the antenna array are the leakages of the space harmonics. The first part chronicles the leaky-mode leakages in a corner-fed square patch. First, the measured peak RPA (relative power absorbed, 1-|S11|2-|S21|2) values of the two-port corner-fed square patch (two-port test circuit) are reported. The peak values are occurred periodically. Such periodicity of frequencies and the phenomenon of increasing losses at higher frequencies enable us to link these peak frequencies to leaky-mode excitations. The maximum available power gain (GA,max), obtained by simultaneously complex conjugate matched impedance at the referenced two ports of the test circuit, depicts that 1) nearly loss-free transmission parameter outside the leaky-mode regions and 2) substantial losses inside the leaky-mode regions. This result suggests that the leaky modes are the main sources causing losses for the two-port test circuit. The one-port properties of the two-port patch with the second port opened are then investigated. The degenerated (0,N) and (N,0) modes (N=1, 2, 3 and 4), calculated by the cavity model method, fall into the strong leakage regions from the first to the fourth higher-order leaky modes. The well-known leaky line’s frequency-scanning characteristics also appear in the one-port test circuit. Lastly, a two-dimensional (2-D) transmission-line model of the one-port test circuit is proposed. This model uses two orthogonal modal currents as excitations to stimulate the corner-fed square patch. At 22.60 GHz, in the fourth higher-order leaky mode (EH4) region, the current distributions obtained by the 2-D transmission-line model closely agree with those of the full-wave simulation. This consistency shows that the damped-oscillation current distributions of the corner-fed square patch at 22.60 GHz are caused significantly by the multiple reflections of the leaky mode. Furthermore, at the resonant frequencies of the patch, the tangled bound-mode resonance of the EH0 mode can enhance the leaky-mode leakages. In the second part, the author proposes a periodic structure derived from a microstrip on a perforated ground plane with anti-symmetric perturbations. The leaky microstrip radiates mainly a pair of forward and backward beams. The new leaky line design employs the concept of space-harmonic modulation. The dispersion characteristics of space harmonics are established and shown in a Brillouin diagram. Each space harmonic is denoted by its complex propagation constant . represents a traveling-wave component of the nth higher-order spatial component in association with the EHm mode: the superscript, +(-), signifies a forward (backward) traveling wave. For the particular leaky line design, and space harmonics, both showing odd-symmetric field polarization, and both outside the triangular Brillouin region, form the backward and forward leaky waves, respectively. When the leaky lines are evenly and collinearly tied, an 11.5 GHz radial antenna array prototype is formed, and emits a conical beam, showing a 3-dB beamwidth of 24o at the flare angle of 31o. In the third part, the author would propose a concept of a millimeter-wave microstrip reflectarray incorporating higher-order EH2 leaky mode. Additionally, the stop-band characteristic of the periodic microstrip with anti-symmetric perturbations is further studied.

Experiments were performed to examine the shear resistance of heavily reinforced I-beams. Six I-beams with identical cross sections were constructed using high strength self-consolidating concrete, and were tested under monotonic anti-symmetric loading. All specimens had almost the same amount of longitudinal reinforcement, which provided sufficient flexural capacities. There were two variables: shear span and shear reinforcement ratio. Test results showed that ACI code was too conservative in predicting the shear strengths of heavily shear reinforced I-beams, and the shear strength limit for deep beams should be increased to account for the benefit of high strength concrete. However, doubling the amount of stirrups did not improve the ultimate shear resistance much. The three beams that contained around 2.45% stirrups showed over-reinforced shear failures. Longitudinal flange cracking occurred to every specimen due to lack of cross tie reinforcement in the flanges, and it was believed to have reduced the ultimate shear strength.

碩士<br>國立臺灣科技大學<br>機械工程系<br>103<br>This study investigated the vibration characteristics of two-layered piezoelectric disks with regard to the solid-liquid coupling effect in pump devices. Experimental measurements and finite element numerical calculations were used to determine the resonant frequencies and mode shapes of two piezoelectric disks, which could be used to promote the flow of air, water, and glycerin in in-phase and anti-phase motions. Two piezoelectric pumps were designed to verify the solid-liquid coupled vibrations of the two-layered piezoelectric disks using on pumps with piezoelectric disks located above the surface of the fluid 1) under quasi-free boundary condition and 2) under rim-clamped boundary condition. The first pump has a piezoelectric bimorph bonded to PDMS polymer, such that resonant vibrations produce changes in the volume of the chamber, which increases the flow of fluid. Another is a piezoelectric disk embedded on the rim of pump chamber to promote the flow of liquid by peristaltic motion. Three experimental techniques were used to determine the solid-liquid coupled vibration characteristics. Electric speckle pattern interferometry (ESPI) was used to measure the resonant frequencies and mode shapes associated with the vibration of two-layered piezoelectric disks interacting with fluids. Second, a laser Doppler vibrometer (LDV) was used to obtain the frequency spectrum of vibrating displacement using dynamic signal swept-sine analysis. The third experiment involved analyzing impedance in the piezoelectric bimorphs in order to identify the resonant frequencies and anti-resonant frequencies of the piezoelectric material under the influence of a fluid. Finite element method (FEM) was used for the analysis of vibration characteristics associated with the interaction between the fluids and piezoelectric-solid elements with acoustic elements. All experimental results are compared with the solid-liquid coupled vibration characteristics calculated using FEM. Finally, the two types of piezoelectric pumps were operated at resonant frequencies in order to measure the flow rate from input water. Finite element numerical calculations of resonant frequencies and mode shapes presented good agreement with experimental measurements.