Foundation performance is controlled significantly by the stress-strain behavior of the underlying soils. For geomaterials, the small-strain shear modulus Gmax is a fundamental stiffness applicable to both monotonic static and dynamic loading conditions, as well to both drained and undrained loading. Yet, Gmax is too stiff for direct use in computing foundation displacements. The main objectives of this research are to: (1) explore the scaled parallelism between the stress-strain-strength behavior of the single soil element response and the load-displacement-capacity of a shallow foundation system supported on soil; (2) develop a methodology for evaluating the performance of vertically-loaded footings using a rational framework based on the small-strain modulus Gmax, large-strain strength ( and #964;max or su) and strain at failure ( and #947;f); and (3) calibrate the proposed method using a foundation database of full-scale load tests under both undrained and drained conditions. In geotechnical practice, foundation bearing capacity is handled as a limit plasticity calculation, while footing displacements are evaluated separately via elastic continuum solutions. Herein, a hybrid approach is derived that combines these two facets into a closed-form analytical solution for vertical load-deflection-capacity based on numerical studies. Here, a non-linear elastic-plastic soil model was developed to simulate the stress-strain-strength curves for simple shearing mode (LOGNEP) for each soil element. The model was encoded into a subroutine within the finite difference program FLAC. A large mesh was used to generate load-displacement curves under circular and strip footings for undrained and drained loading conditions. With proper normalization, parametric foundation response curves were generated for a variety of initial stiffnesses, shear strengths, and degrees of non-linearity in the soil stress-strain-strength response. Soil stress-strain non-linearity is described by a logarithmic function (Puzrin and Burland, 1996, 1998) that utilizes a normalized strain xL that relates strain at failure and #947;f, shear strength ( and #964;max or su), and small-strain stiffness Gmax, all having physical meaning. A closed-form algorithm is proposed for generating non-linear load-displacement curves for footings and mats within an equivalent elastic framework. The proposed method was calibrated using a database of well-documented footing load tests where soil input parameters were available from laboratory and/or in-situ field test results.

The pattern reduction (PR) algorithm we proposed previously, which works by eliminating patterns that are unlikely to change their membership during the convergence process, is obviously one of the most efficient methods for reducing the computation time of clustering algorithms. However, it is limited to problems with solutions that can be binary or integer encoded, such as combinatorial optimization problems. As such, this study is aimed at developing a new pattern reduction algorithm, called pattern reduction over continuous space, to get rid of this limitation. Like the PR, the proposed algorithm consists of two operators: detection and compression. Unlike the PR, the detection operator is divided into two steps. The first step is aimed at finding out subsolutions that can be considered as the candidate subsolutions for compression. The second step is performed to ensure that the candidate subsolutions have reached the final state so that any further computation is eventually a waste and thus can be compressed. To evaluate the performance of the proposed algorithm, we apply it to metaheuristics for clustering.

Dendrimer-encapsulated nanoparticles (DENs) were prepared, characterized, and immobilized on solid surfaces. The resulting films were applied as electrocatalysts for the oxygen reduction reaction (ORR). First, the synthesis, physical and chemical properties, and stability of Pd DENs prepared within poly(amidoamine) (PAMAM) dendrimers were studied in aqueous solution. In this part of the study, the following new findings were reported: (1) the maximum Pd ion loading in the dendrimer was correlated to the number of interior amines available for complexation; (2) Pd DENs could be synthesized within amine-terminated Pd DENs by controlling the solution pH; (3) the oxidative stability of Pd DENs was significantly improved by removing solution-phase impurities; (4) exposure to hydrogen gas reversibly converts partially oxidized Pd DENs back to the zerovalent state. Second, Pt and Pd DENs were prepared using amine-terminated PAMAM dendrimers, and then the free amine groups on the periphery were used to immobilize Pt and Pd DENs onto Au surfaces via an intermediate self-assembled monolayer. The resulting DEN films were more robust and had higher coverages of DENs compared to the DEN films prepared via physisorption. Third, Pt DENs were prepared and immobilized on glassy carbon electrodes using an electrochemical coupling method. The resulting films were electrochemically active for the ORR. These electrocatalytic monolayers were also robust, surviving up to 50 consecutive electrochemical scans for ORR and sonication in acid solution with no significant change in activity. Finally, PtPd bimetallic nanoparticles containing an average of 180 atoms (~1.8 nm in diameter) and composed of seven different Pt:Pd ratios were prepared within sixth-generation, hydroxyl-terminated PAMAM dendrimers. Transmission electron microscopy and single-particle energy dispersive spectroscopy confirmed the sizes and compositions of the particles. These DENs were immobilized on glassy carbon electrodes, and their electrocatalytic properties were evaluated as a function of composition using cyclic voltammetry and rotating disk voltammetry. The results showed that the maximum rate for the ORR occurs at a Pt:Pd ratio of 5:1, which corresponds to a relative mass activity enhancement of 2.5 compared to otherwise identical monometallic Pt nanoparticles.

The constant matrix multiplication is one of the key operations in many applications including digital signal processing, communication, and coding. In general, constant matrix multiplication can be expressed as bit-level Boolean functions. Then, common subexpression elimination (CSE) can be used to reduce the area cost of realizing these bit-level functions by finding the shared common factors among these bit-level equations. The proposed circuit generator performs logic reduction on the input Boolean functions and produces the simplified Verilog HDL codes as output. Then the simplified code is fed into Synopsys Design Compiler for further logic minimization and technology mapping to generate gate-level netlists. In this thesis, we present ten different CSE algorithms for logic reduction of the bit-level Boolean functions. The comparisons include both the architecture-level technology-independent results and the Synopsys synthesized technology-dependent results. According to the experiments, we observe that our CSE can effectively reduce the area cost. We also apply the CSE to the design of the Advanced Encryption Standard (AES) in cryptography.

It is well known that the finite difference time domain (FDTD) method is a powerful numerical analysis tool for solving electromagnetic problems. In a simulated area, in order to discretize an object which is much smaller than the others, a very small space increment is needed and hence the time step should be decreased too for stability consideration in traditional FDTD. The small space and time increments will respectively increase the memory requirement and calculation time. To overcome these problems, some numerical methods were developed, such as the subcell and nonuniform grid method, to handle the small feature size. This thesis describes an efficient method for generating FDTD subcell equations. We construct a second order macromodel system instead of the subcell region in conventional FDTD. The macromodel system can be reduced with model order reduction techniques (MOR) and then translated into new FDTD update equations. When the problem contains several objects of the same size and material properties, the MOR subcell has the advantage of reusability. This means that the reduce-order model of the object needs to be generated only once nonetheless can be applied to every position where the objects originally occupied.

No description available.

No description available.

Bottom water hypoxia and its influence on the environment have been topics of increasing concern for many coastal regions. This research addresses both spatial and temporal variability in sediment biogeochemistry at the southeastern region of Corpus Christi Bay, TX, where seasonal (summer) hypoxia occurs. Traditional techniques for determination of a variety of dissolved and solid components, benthic oxygen demand, and sulfate reduction rates were augmented by measurements using solid state microelectrodes to simultaneously determine concentrations of dissolved O2, Mn2+, Fe2+, and [sigma]H2S in multiple small - interval (1 mm) depth profiles of sediment microcosms. Oxygen concentrations in the overlying water were manipulated in the sediment microcosms and electrode depth profile measurements were made over ~ 500 hours of experimentation. Laboratory and field microelectrode results were in good agreement for both norm - oxic and anoxic time periods. Results indicated that iron (Fe2+) and sulfide ([sigma]H2S) were the redox reactive species in these sediments. During hypoxic conditions an upward migration of dissolved Fe2+and [sigma]H2S through the sediment column and, at times, into the overlying water was observed as the dissolved oxygen concentrations decreased. A corresponding decline in the vertical extent of these redox species occurred when the overlying water was re-oxidized. When both dissolved iron and sulfide coexisted, FeS minerals were formed in the sediment, preventing sulfide diffusion into the overlying water. However, after a long duration of hypoxia (> 200 hours) this buffering capacity was exceeded and both iron and sulfide penetrated into the overlying waters. Results indicated that iron may have a greater influence on hypoxia than sulfide because its concentration in the overlying waters during induced hypoxia was an order of magnitude greater than those of sulfide. Moreover, in the southeastern region of the Bay, where mixing was minimal and the water column was shallow, the sediments alone may have caused the onset of the hypoxic event in a relatively short time period (< 5.5 days). These results demonstrated that in shallow marine environments where seasonal hypoxia occurs, such as Corpus Christi Bay, the associated major changes that take place in the sediment biogeochemistry must be included in benthic - pelagic models for overlying water hypoxia.

The objective of this project is to design a tool for moderate cross section reduction of bars that are deformed within a channel slider tool that is used for equal channel angular extrusion (ECAE). The bars that are deformed via ECAE have an initial square cross section with a nominal value of 1.00 in2 and aspect ratios (length/width) ranging between 4 and 6. A systems engineering design methodology is used to generate a topbottom approach in the development of the tool's design. This includes defining a need statement, which is the "Need for an area reduction extrusion tool to replace the current practices of machining ECAE processed billets". The system functions and requirements are defined next and used to generate three concepts that are compared to select the winning concept for further refinement. Major components of the selected tool are: a container, ram, base plate, punch plate, four die-inserts, four wedges and four flange locks. For materials, such as copper (C10100) and aluminum (Al6061-T6), that can be processed by this tool, the upper bound extrusion pressure, which is derived by limit analysis, is set at 192 ksi. The upper bound extrusion pressure is constrained by the buckling limit of the ram, which is 202 ksi. The maximum wall stress experienced by the container is 113 ksi. For materials with the same cross section and dimensions, fixed end conditions of the Ram support larger bucking loads when compared to other end conditions such as rounded ends or rounded-fixed ends. With the application of the upper bound method, an increase in the extrusion ratio of the tool causes a corresponding rise in the optimal cone angle of the die further translating to a rise in the extrusion pressure.

This study takes ¡§the Health food of nutrition¡¨, ¡§Cosmetic skin care products¡¨, and ¡§the Articles for cleanness¡¨ as the representatives of direct-selling products. With the network questionnaires to investigate ¡§Consumer characteristics¡¨ of ¡§Netizens¡¨, and how they influence the levels of various perceived risk, and the helpfulness of risk reduction strategies, with SEM to analysis the structure between seven kinds of perceived risk, with the method which was used by Roselius (1971) to measure the helpfulness of risk reduction strategies, and with Cluster, Correlate, ANOVA to analysis the way how ¡§Consumer characteristics¡¨ of ¡§Netizens¡¨ influence perceived risks and risk reduction strategies, and the way how perceived risks influence risk reduction strategies. There are five important conclusions, describing as following: 1. There are differences between three kinds of direct-selling products on the perceived risks of ¡§Performance¡¨, ¡§Psychology¡¨, and ¡§Overall¡¨. 2. In the structure of constructing the path to form the ¡§Overall risk¡¨ by six kinds of risks, the direct and indirect result exists at the same time. 3. Different ¡§Consumer characteristics¡¨ will influence different kinds of perceived risks, and the most meaningful characteristics are ¡§the Types of direct-selling consumers¡¨ and ¡§the attitude toward shopping through direct-selling¡¨. 4. Different ¡§Consumer characteristics¡¨ will influence the helpfulness of different risk reduction strategies, and the most meaningful characteristics are ¡§Age¡¨, ¡§Location¡¨, and ¡§the Types of direct-selling consumers¡¨. 5. Various perceived risks will influence the helpfulness of different risk reduction strategies, and only the helpfulness of ¡§Free sample¡¨ will be enhanced. There are three points about managerial implications and suggestions, describing as following: 1. ¡§Private testing¡¨, ¡§Government testing¡¨, and ¡§Major brand image¡¨ are capable of reducing the ¡§Performance risk¡¨ effectively, and then reduce the levels of ¡§Overall risk¡¨ perception to decrease the perceived sacrifice of product value and to enhance it to the original levels of product value. 2. For the ¡§Netizen¡¨ who are not becoming a member, and not using direct-selling products quite often, ¡§Free sample¡¨ with ¡§Replace product guarantee¡¨ or ¡§Money-back guarantee¡¨ are capable of reducing the levels of risk perception effectively. 3. In the long run, direct-selling companies should endeavor to prove the image of direct-selling, because ¡§the attitude toward shopping through direct-selling¡¨ is an important factor to influence the levels of risk perception and the helpfulness of the risk reduction strategies. And ¡§Industry autonomy¡¨ is a good risk reduction strategy, but not be known by the public. There is a long way for TDSA ¡]Taiwan Direct Selling Association¡^ to go, because popularity and public trust are insufficient. Key words: Consumer characteristics, Perceived risk, Risk reduction strategy