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Sound transmission loss of vehicle seals was studied in this thesis. Reverberation room test and semi-anechoic chamber test were respectively studied. By comparing the sound pressure level, sound intensity level and average sound power level at the receiving side, it proved that a simple sound pressure level test may obtain same measurement accuracy when there is little reflected sound. A semi-anechoic chamber was designed for testing sound transmission losses of the seals on a trial vehicle. By comparing the sound pressure levels between the location of the passenger ear and door area, it proved that most of outside sound energy passed through the door seals into the interior. The sound transmission losses of different sealing conditions were measured which included well sealed and imperfectly sealed conditions; Sound pressure levels at passenger’s ear in three different types of vehicles were also compared, these comparison results indicated this laboratory was capable of distinguishing different sealing conditions. The installation procedure was compared with the one in reverberation room test. Numerical analysis showed that the latter method produced a different compression shape which would definitely influence the sound insulation abilities of the seals.   The transmission mechanism of the acoustic waves through a vehicle seal was also discussed. Contact analysis showed high compression ratio leaded to tremendous inner stress intensity. But any further increase of the contact depth would not improve the effect of wind noise prevention. A vehicle seal with a complex shape was replaced by a simple model. The sound transmission theory of multiple partitions on the basis of mass law was applied. Whereas, compared with the experimental result, a different trend in the high frequency range was found. When taking the transmission though the side material and integration of incident angle into account, the result was quite similar to the experimental one. FEM analysis was also performed. The majority of sound power was believed to transmit along the seal wall into the interior instead of passing through the multiple partitions. A distorted circular duct model is believed to be close to the real geometry. / QC 20101117

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This thesis deals with toric ideals associated with finite simple graphs. In particular we establish some results pertaining to the nature of the generators and syzygies of toric ideals associated with finite simple graphs. The first result dealt with in this thesis expands upon work by Favacchio, Hofscheier, Keiper, and Van Tuyl which states that for G, a graph obtained by "gluing" a graph H1 to a graph H2 along an induced subgraph, we can obtain the toric ideal associated to G from the toric ideals associated to H1 and H2 by taking their sum as ideals in the larger ring and saturating by a particular monomial f. Our contribution is to sharpen the result and show that instead of a saturation by f, we need only examine the colon ideal with f^2. The second result treated by this thesis pertains to graded Betti numbers of toric ideals of complete bipartite graphs. We show that by counting specific subgraphs one can explicitly compute a minimal set of generators for the corresponding toric ideals as well as minimal generating sets for the first two syzygy modules. Additionally we provide formulas for some of the graded Betti numbers. The final topic treated pertains to a relationship between the fundamental group the finite simple graph G and the associated toric ideal to G. It was shown by Villareal as well as Hibi and Ohsugi that the generators of a toric ideal associated to a finite simple graph correspond to the closed even walks of the graph G, thus linking algebraic properties to combinatorial ones. Therefore it is a natural question whether there is a relationship between the toric ideal associated to the graph G and the fundamental group of the graph G. We show, under the assumption that G is a bipartite graph with some additional assumptions, one can conceive of the set of binomials in the toric ideal with coprime terms, B(IG), as a group with an appropriately chosen operation ⋆ and establish a group isomorphism (B(IG), ⋆) ∼= π1(G)/H where H is a normal subgroup. We exploit this relationship further to obtain information about the generators of IG as well as bounds on the Betti numbers. We are also able to characterise all regular sequences and hence compute the depth of the toric ideal of G. We also use the framework to prove that IG = (⟨G⟩ : (e1 · · · em)^∞) where G is a set of binomials which correspond to a generating set of π1(G). / Thesis / Doctor of Philosophy (PhD)

Although clays are generally considered stable materials under seismic conditions, recent failures initiated in clay layers after earthquakes have emphasized the need to study the cyclic and post-cyclic behavior of these materials. Moreover, if strength loss as a result of cyclic loading were to occur in the material comprising the dam and/or dam foundation, the consequences of failure could be substantial. The objective of this study is to evaluate the effect of plasticity characteristics, mineralogical composition, and accumulated energy on the cyclic behavior, post-cyclic shear strength and the degradation in shear strength due to cyclic loading in normally consolidated clays. Seventeen soil samples prepared in the laboratory from kaolinite, montmorillonite, and quartz were tested using static and cyclic simple shear apparatuses. In addition, the results of cyclic simple shear tests on twelve natural samples were provided by Fugro Consultants, Inc. in Houston, TX. Using the results, cyclic strength curves were developed to represent 2.5%, 5% and 10% double amplitude shear strains. These curves were used to examine the influences of mineralogical composition, plasticity characteristics and shear strain on the cyclic resistance of soil samples. A power function was used to represent the cyclic strength curves. The samples were found to become increasingly resistant to cyclic loading as the plasticity index increased. Moreover, the soils with montmorillonite as the clay mineral were noted to have consistently higher cyclic resistances than the soils with kaolinite as the clay mineral. By examining the power functions, it was found that the cyclic strength curve approaches linearity as the plasticity index increases in soils having kaolinite as the clay mineral. However, the opposite trend is observed in soils having montmorillonite as the clay mineral. The study shows that the post-cyclic shear strength increases with increasing plasticity index. Moreover, the post-cyclic shear strengths of soils with montmorillonite as the clay mineral were significantly higher than the post-cyclic shear strengths of soils with kaolinite as the clay mineral. The degradation in shear strength due to cyclic loading appeared unaffected by mineralogy, but a greater reduction in strength was noted with decreasing plasticity index. The post-cyclic shear strength was also found to reduce as the number of cycles required to cause 10% double amplitude shear strain increased. The energy approach considering the accumulated energy per unit volume in the soil mass as a result of cyclic loading was also utilized in this study. The results from the energy approach were independent of the cyclic wave form, but were still dependent on the amplitude of the cyclic load used during the testing. An increase in the amplitude of the cyclic loading function results in a decrease in the accumulated energy per unit volume. Furthermore, an increase in the liquid limit and/or plasticity index of the soils containing kaolinite as the clay mineral shows an increase in the accumulated energy, whereas an increase in plasticity of the soils containing montmorillonite as the clay mineral results in a decrease in the amount of accumulated energy. In both types of materials, the amount of accumulated energy per unit volume is found to increase with increasing double amplitude shear strain. Relationship between the ratio of post-cyclic undrained shear strength to the baseline undrained shear strength and the accumulated energy is also determined. / Ph. D.

Entre los parámetros de cálculo más importantes en la Mecánica de Rocas, se encuentra la Resistencia a Comprensión Simple, como un valor que nos ayuda a la caracterización y estudio del comportamiento de los macizos rocosos. Contar con una buena correlación entre el ensayo de Carga Puntual (PLT) y de Resistencia a Compresión Simple (RCS) puede ser de gran importancia, pues se obtienen beneficios por la realización de ensayos más rápidos y económicos, que pueden aportar la misma seguridad en los cálculos de estructuras y actuaciones en macizos rocosos. Un paso previo para poder aplicar dicha correlación es disponer de un buen método de determinación de la Resistencia a la Carga Puntual. Esa correcta determinación es bastante confiable cuando se dispone de un número suficiente de ensayos con probetas de la misma naturaleza, pero habitualmente no es así y debe aplicarse un factor de corrección por tamaño F=(De / 50)? , con un ? = 0,45. En el presente trabajo se estudia la adecuación de dicho factor y se inicia el estudio de un factor alternativo, para el que se propone una expresión en la que el exponente ? es del tipo ?* = C1 - C2 x Is(50),F, donde Is(50),F es el índice de resistencia a la Carga Puntual obtenido con el factor F normativo. También, es importante conocer antes de realizar los ensayos de PLT, las dimensiones óptimas de las probetas (relación L / D) para una adecuada aplicación de la carga (P). El trabajo se centra en las Calizas de la Comunidad Valenciana (España) porque representan un porcentaje muy elevado de las rocas existentes en esa comunidad. Para su ejecución se han realizado más de 700 ensayos in-situ y en laboratorio, de los cuales 346 son ensayos de PLT, 45 ensayos de RCS y el resto son determinaciones de otros parámetros caracterizadores como son: peso específico y porosidad, durabilidad al desmoronamiento (Slake-Durability), velocidad ultrasónica, etc. / Galván Ceballos, MA. (2011). Estudio del ensayo a carga puntual en materiales calizos de la Comunidad Valenciana. Propuesta de modificación del factor de corrección por tamaño y correlación del ls(50) con la Resistencia a Compresión Simple [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/10526