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  • Thesis

  • Authors: Nashed, Rafeek (2006)

  • Liquefaction of saturated loose granular sand and non-plastic silty sand deposits during seismic loading has caused significant damage to structures and highway systems in almost all major earthquakes. Sand deposits densified by dynamic compaction (DC) are more resistant to liquefaction, and have performed well during earthquakes. Silty sand deposits appear to densify and. perform well when improved by DC supplemented with wick drains. The current practice for evaluating feasibility and choosing the operational parameters of the DC technique at a site depends mainly on field trials, past. experience at. similar sites, and empirical equations based on reported records. Rational analytical methods are needed to improve the state of practice. This dissertation presents an analytical ...

  • Thesis

  • Authors: Li, Kun (2006)

  • This research is aimed at improving existing methods for evaluating liquefaction potential of soils using probabilistic approach. The research deals with several closely related studies. First, a Cone Penetration Test (CPT)-based model for calculating liquefaction resistance is developed using artificial neural network approach, taking advantage of a recently updated seismic loading model and a comprehensive data set of CPT-based liquefaction/no-liquefaction case histories. Second, the liquefaction resistance model developed is incorporated into the formulation of liquefaction potential index, and the various issues related to the liquefaction potential index are examined using probability concept. Third, general applicability of the commonly used index properties-based criteria for...

  • Thesis

  • Authors: Wang, Hao (2006)

  • Mechanistic and phenomenological models and careful parameter estimations are presented through both aquatic and terrestrial ecosystems. The stoichiometric modeling of the bacteria-algae lake system is relatively new, while the lemming population cycle has attracted the attention of several generations of theoretical and experimental biologists and continues to be an issue of controversy. Bacteria-algae interaction in epilimnion is modeled with explicit consideration of carbon (energy) and phosphorus (nutrient). Global qualitative analysis and bifurcation diagrams of this model are presented. Competition of bacterial strains are modeled to examine Nishimura's hypothesis that in severely P-limited environments, such as Lake Biwa, P limitation exerts more severe constraints on the gr...

  • Thesis

  • Authors: Yu, Piyong (2006)

  • Fiber reinforced polymer (FRP) systems have demonstrated to be effective for the retrofitting of masonry walls and reinforced concrete (RC) members. Prestressing of the FRP can further improve the serviceability and capacity of the strengthened elements. This dissertation presents the development of one mechanical device to prestress glass FRP (GFRP) bars and another device to prestress carbon FRP (CFRP) sheets and their applications for the retrofit of unreinforced masonry (URM) walls and RC beams. For the GFRP bar system, the bars are installed in grooves of the URM walls with near surface mounted (NSM) technique and then post-tensioned with the hand-held device to partially close cracks and increase shear capacity of the walls. For the CFRP sheet system, the sheets are temporari...

  • Thesis

  • Authors: Lee, Chung-Sheng (2006)

  • To successfully use the fiber-reinforced-polymer (FRP) overlay technique for the seismic retrofit and the blast-hardening of RC columns, the mechanical behavior of the FRP-confined concrete needs to be understood and its response needs to be accurately predicted. Although a number of studies have been conducted to-date, it is still not clear how the main parameters affect the axial stress-strain response of a FRP-confined concrete cylinder. In particular, while it is understood that FRP jackets inhibit dilatancy, current models do not capture the physics that leads to ascending or strain-softening responses vs. the level of lateral confinement. In this dissertation, a dilatancy-based analytical model for FRP-jacketed circular concrete cylinders in axial compression was developed. ...

  • Thesis

  • Authors: Pelechano Gomez, Nuria (2006)

  • The simulation of realistic, large, dense crowds of autonomous agents is still a challenge for the computer graphics community. Typical approaches either look like particle simulations (where agents `vibrate' back and forth) or are conservative in the range of motion possible (agents aren't allowed to `push' each other). Our HiDAC system (High Density Autonomous Crowds) focuses on the problem of simulating the local motion behaviors of crowds moving in a natural manner within dynamically changing virtual environments. This is achieved by applying a combination of psychological and geometrical rules layered on top of a social forces model. The results show: elimination of agent `shaking' behavior, fast perception, and a wide variety of emergent behaviors including: bi-directional flo...

  • Thesis

  • Authors: Nien, Chufeng (2006)

  • Let F denote a p-adic field and D a quaternion division algebra over F. Ginzburg-Rallis models (abbreviated as G-R models), were discovered in "The exterior cube L-function for GL(6)" by D. Ginzburg and S. Rallis when they computed exterior cube L-functions for GL6. They made a conjecture about the relation between nonvanishing of the central value of exterior cube L-function for GL6 and the realization of G-R models on quaternion algebras. This conjecture motivates the investigation of G-R models on GL6(.') and GL3(D). In the first part of this paper, the proofs of uniqueness of G-R models on GL6(.') and GL3(D) are given. Klyachko models, also known as Whittaker-symplectic models, were first established by A.A. Klyachko in `Models for the complex representations of the groups GL(...

  • Thesis

  • Authors: Pickering, Brian F. (2006)

  • As etiological agents of anthrax, plague, and tularemia, which can be used as biological weapons, the United States Centers for Disease Control and Prevention (CDC) has classified Bacillus anthracis, Yersinia pestis, and Francisella tularensis as Category A pathogens. Currently, the response to a bioterrorist attack utilizing these agents would be largely reactive as there are no approved vaccines for general public use. Post-exposure antibiotic treatment is effective if it is administered shortly after exposure to the pathogens and due to their long term treatment schedule, the antibiotics tend to be associated with well-known severe side effects. Antibodies that are highly specific for traditional virulence factors associated with the pathogens represent a beneficial addition to t...

  • Thesis

  • Authors: Zhang, Xin (2006)

  • Advances in chromatography have led to two recent active areas of study: the reduction of particle size for column packing and development of monolithic materials. Reducing the size of the packing material leads to an increase in chromatographic efficiency and a decrease in the analysis time. The monolithic column is composed of one single piece of material with through-pores that offers very high permeability, thereby, allowing the column can offer a variable external porosity and operation at high linear velocity with low pressure requirements. The performance of commercially available columns, a monolith and a sub-2 gm particle packed column was examined. Higher efficiencies were obtained with the sub-2 gm particle packed column. Very high pressures 14,000 psi were required to op...