In present dissertation, field-driven quantum well (QW) device is proposed to obtain high-speed and high-efficiency all-optical wavelength converter (AOWC). A new type QW material, InGaAsP/InGaAlAs, is employed to improve not only quantum confined Stark effect, but also carrier life time during high electric field excitation. The bandwidth as well as efficiency can be enhanced. Thus, the slow gain recovery mechanism (~100ps) from conventional semiconductor optical amplifier (SOA)-based AOWC can be overcome. The dispersion- and efficient- limited fiber-based AOWC (~10ps) can also be avoided. -3dB frequency bandwidth exceeding 40GHz for both electrical-to-optical and photocurrent response has been observed from InGaAsP/InGaAlAs waveguide of AOWC, leading to above 40GHz bandwidth in optical-to-optical response. A 40 Gb/s measurement setup is finally used for testing eye-diagram and bit-error-ratio in order to verify the data transmission of AOWC. Low power penalty with 0.5 dB comparing with back-to-back system performance is measured, suggesting InGaAsP /InGaAlAs waveguide is applicable to all-optical processing. By exciting short optical pump pulse in such waveguide, as short as 6.4ps probe pulse is observed, breaking through 10ps order in conventional type of QW and thus indicating the plausibility of performing 100Gb/s all optical processing.

Modeling software with object-oriented technique and unified modeling language have become the new paradigm of modern information systems analysis and design. In addition, many approaches and CASE tools have been introduced to facilitate the transformation from class diagram to object-relational database and application template and thereby enhance the efficiency of system development. Model-driven architecture (MDA) and Rational Rose is such an approach and CASE tool, respectively. This research presents a systematic methodology which integrated the MDA concept to transform the class diagram into object-relational database and application template during the system development process. A real-world case using the integrated techniques is presented and the Rational Rose is used to illustrate the concepts, application, and the advantages of using the proposed methodology. With this approach, the system developer can transform class diagram into object-relational database and application template automatically and thereby enhance the efficiency of system development.

In this dissertation, we develop analytical and computational tools for performance analysis and design of large-scale service systems. The dissertation consists of three main chapters. The first chapter is devoted to devising efficient task assignment policies for large-scale service system models from a rare event analysis standpoint. Specifically, we study the steady-state behavior of multi-server queues with general job size distributions under size-interval task assignment (SITA) policies. Assuming Poisson arrivals and the existence of the alpha-th moment of the job size distribution for some alpha> 1, we show that if the job arrival rate and the number of servers increase to infinity with the traffic intensity held fixed, a SITA policy parameterized by alpha minimizes in a large deviation sense the steady-state probability that the total number of jobs in the system is greater than or equal to the number of servers. The optimal large deviation decay rate can be arbitrarily close to the one for the corresponding probability in an infinite-server queue, which only depends on the system traffic intensity but not on any higher moments of the job size distribution. This supports in a many-server asymptotic framework the common wisdom that separating large jobs from small jobs protects system performance against job size variability. In the second chapter, we study constraint satisfaction problems for a Markovian parallel-server queueing model with impatient customers, motivated by large telephone call centers. To minimize the staffing level subject to different service-level constraints, we propose refined square-root staffing (SRS) rules, which preserve the insightfulness and computational scalability of the celebrated SRS principle and yet achieve a stronger form of optimality. In particular, using asymptotic series expansion techniques, we first develop refinements to a set of asymptotic performance approximations recently used in analyzing large call centers, namely, the Quality and Efficiency Driven (QED) diffusion approximations. We then use the improved performance approximations to explicitly characterize the error of conventional SRS and further obtain the refined SRS rules. Finally, we demonstrate how the explicit form of the staffing refinements enables an analytical assessment of the accuracy of conventional SRS and its underlying QED approximation. In the third chapter, we study a fluid model for many-server Markovian queues in changing environments, which can be used to model large-scale service systems with customer abandonments and time-varying arrivals. We obtain the stationary distribution of the fluid model, which refines and is shown to converge, as the environment changing rate vanishes in a proper way, to a simple discrete bimodal approximation. We also prove that the fluid model arises as a law of large number limit in a many-server asymptotic regime.

Expansive soils cause more damage to structures annually than a combination of other major natural disasters. Because of the cost to our society, all means and methods need to be fully explored to mitigate the problems associated with expansive soils. This study will present a foundation design approach that is under utilized in this application, driven piles. The main objective of the study is to present pile test results and analysis from four driven pile project sites in three types of expansive soils found in central Texas: Del Rio formation, Taylor/Navarro formation, and expansive alluvium. Observations of the pile driving operations will be reported to highlight pile design considerations like predrilling and open versus close-ended pipe piles and the type of equipment involved. High strain dynamic pile tests were conducted on each of the four studies with rigorous signal matching analysis from the CAse Pile Wave Analysis Program (CAPWAP). Ultimate pile capacities ranged from 73 to 311 kips with an average of 61% of the total capacity coming from the pile shaft and were two to six times the structural capacity needed. Static design methods under-predicted, dynamic formulas over-predicted, and wave equation analysis conducted with GRLWEAP closely modeled test results. Average unit skin frictions ranged from 0.55 to 4.7 ksf. Restrike pile tests of 1 to 17 days after initial driving reported 30 to 100% shaft capacity gain. All open-ended pipe piles driven produced soil plugs ranging from 4 to 14 feet thick, and it was observed that harder driving conditions produced thinner soil plug thicknesses. Small diameter, thick-walled, open-ended pipe piles reached penetration of twice the depth of designated zone of seasonal moisture change without problem. The observed production rate of the driven piles was on average 8 minutes which implied daily production of 15 to 40 piles. Predrills or augered holes should be specified for underground obstructions found in soil investigation. Future studies on pile-supported foundations should measure localized movement correlated with seasonal moisture changes in expansive soil, or active zone, to confirm long-term performance. Also uplift forces need to be observed from tests on fully-instrumented and loaded driven piles to determine required pile embedment length below the active zone to withstand movement. / text

In some configurations of compact, biofilm based photobioreactors, algae grow on a porous substrate that acts as the support system for the cells providing them with the necessary water and nutrients as well as carrying away their secreted products. The flow in these porous media can be driven by evaporation, mimicking the function of a synthetic leaf. The surface properties of the porous medium as well as the presence of a second immiscible phase in the fluid transported can significantly alter the transport capability and evaporative performance of the porous medium. The focus of this study is to investigate these effects through an experimental study. A dilute, 1% emulsion of lauric acid (chemical formula: C₁₂H₂₄O₂) in water was prepared using Tween® 80 surfactant. Evaporation driven flow of deionized water and the emulsion through two porous media, a hydrophilic glass fiber membrane and a less hydrophilic poly(vinylidene) fluoride (PVDF) membrane were studied. Experiments were conducted to determine the effect of porous medium and fluid properties on the rate of evaporation. The parameters investigated were the hydrophilicity of the porous medium and the area of the porous medium available for evaporation for both water and emulsion. During the experiment, the mass flow rate of the fluid as well as the temperature and the relative humidity of the ambient air were monitored. The results showed that for dilute emulsions, the rate of evaporation observed was the same as that for water and was dictated by the governing laws of convection applicable to the situation based on the geometry of the setup and the ambient conditions. The response of the porous medium to flow of dilute emulsion showed that the highly hydrophilic glass fiber porous medium rejected any accumulation of the oil phase in the pores, and ejected it out, whereas the lesser hydrophilic PVDF porous medium allowed the pores to be clogged by the oil phase, resulting in change in the properties of the medium. However, the dependence of this observation solely on surface properties of the medium cannot be ascertained as the glass fiber medium had a larger pore diameter than the PVDF medium, and this factor could be of effect. The relative humidity of ambient air affected the rate of evaporation, which implied that the flow was limited by evaporation rather than by the viscous losses in the porous medium. The response of change in rate of evaporation to change in relative humidity showed a high time lag. Also, it was seen that there was a maximum area over which evaporation occurred which was dictated by the capillary pressure generated by the porous medium and the viscous losses for the fluid flow through the medium. Any excess area available for evaporation did not have any effect on the rate of evaporation. Electrospinning, as a simple and effective process for generating fibrous porous media was presented and a sample porous medium was prepared using this method. A parametric analysis of the effect of the potential difference applied between the syringe tip and the collector electrode, and the distance between the tip and the collector on the diameter of fibers produced, was performed. / text

This dissertation is concerned with design, fabrication, and mathematical modeling of three different microactuators driven by light. Compared to electricity, electromagnetic wave is a wireless source of power. A distant light source can be delivered, absorbed, and converted to generate a driving force for a microactuator. The study of light-driven microsystems, still at its early stage, is already expanding the horizon for the research of microsystems. The microactuators of this dissertation include micro-cantilevers driven by pulsed laser, photo-deformable microshells coated with gold nanospheres, and a nano-particles coated micro-turbine driven by visible light. Experimental investigation and theoretical analysis of these microactuators showed interesting results. These microactuators were functioned based on cross-linked, multiple physics phenomenon, such as photo-heating, thermal expansion, photo-chemistry effect, plasomonics enhancement, and thermal convection in rarefied gas. These multiple physics effects dominate the function of a mechanical system, when the system size becomes small. The modeling results of the microactuators suggest that, to simulate a microscale mechanical system accurately, one has to take account the minimum dimension of the system and to consider the validity of a theoretical model. Examples of the building of different microstructures were shown to demonstrate the capacity of a digital-micromirror-device (DMD) based apparatus for three-dimensional, heterogeneous fabrication of polymeric microstructures. / text

No description available.

Methods of determining pile toe capacity for both small displacement driven steel piles and drilled sockets were collected. Working in conjunction with a local consulting firm, records of previous pile driving sites were collected. A process to determine quality data for use in this work was developed by the author including information from geotechnical site investigations, pile driving records and pile driving analysis records. By plotting unconfined compressive strength of rock versus measured ultimate pile toe capacity of these piles, a best fit line of 7.5qu and a series of confidence intervals were established for the site records. This best fit line was compared to all of the previously reviews design methods for calculating ultimate pile toe capacity. Rehnman and Broms (1971) was determined to be the most effective existing method while most of the methods for drilled sockets were overly conservative when applied to small displacement driven steel piles.

Reported in this thesis are the studies of micellar aggregates of four triblock copolymers and the unimolecular micelles of a triblock copolymer. The micelles were prepared from BCF and ACF copolymers. Here A, B, C, and F denote poly(acrylic acid), poly(tert-butyl acrylate), poly(2-cinnamoyloxylethyl methacrylate), and the liquid crystalline poly(perfluorooctylethyl methacrylate) block, respectively. At room temperature (21 oC) in solvents that were selective for the A or B blocks, three of the four copolymers formed exclusively cylindrical micelles regardless of their block ratios. Cylindrical micelles were formed because their geometries best accommodated the mesogen-ordering requirement of the core-forming F block, as supported by the results from wide angle X-ray scattering and differential scanning calorimetric studies. Mesogen-driven cylinder formation was further supported by the observation of ridges formed by collapsed coronal chains on the surfaces of dried cylinders. We also observed a morphological transformation from other micellar morphologies to cylindrical micelles at 70 oC, which is near the isotropic-to-smectic A phase transition temperature for the F blocks. This inter-conversion between the vesicular and cylindrical micelles of an ACF sample could be reversed repeatly by temperature cycling. These results provided additional evidence for the mesogen-driven micellization hypothesis. Unimolecular micelles were prepared from CDC triblock copolymers, where D and C denote poly(dimethylaminoethyl methacrylate) and poly(2-cinnamoyloxylethyl methacrylate), respectively. In selective solvents for the D block at high dilutions, the D chain formed a loop, and the terminal C blocks of the isolated unimer chain associated together as a globule, thus closing the loop and rendering a cyclic structure. Alternatively, the terminal C blocks formed individual globules, thus yielding a pompom-coil-pompom structure. To lock in these structures, the globules were photo-crosslinked. The D block chain was subsequently enlarged for AFM observation through a quaternization step, which increased the chain’s diameter and introduced cations to the chain. The semi-flexible thickened polymer chains and the globules were observed by AFM, confirming unambiguously the hypothesized architectures of the unimolecular micelles. The AFM images also allowed the quantification of the macrocyclic structures, and a correlation between the direct AFM results and determined from a traditional size exclusion chromatography technique. / Thesis (Ph.D, Chemistry) -- Queen's University, 2011-09-26 12:08:28.263

Ensembles of distributed, autonomous and heterogenous entities that are situated in an environment, interacting over both space and time, and striving to uphold some global system coherence, mission, and goal characterize a new class of systems coined Open Computational Systems (OCS). OCS are materializing as a result of various enabling Internet technologies and examples include: ubiquitous computing, proactive computing, autonomic computing, network-centric computing, and network-centric warfare. OCS require a fundamental shift in the way we think about software development. In order to address these issues we advocate a holistic approach where models and tools come together to provide a platform for the building, understanding and monitoring of software based on the notion of these type of systems. In this research project, this was investigated by adopting the generative communication paradigm, a framework for entity communication and collaboration that will allow us to construct systems with characteristics of an OCS. Model-Driven Engineering (MDE) technologies (Domain Specific Modelling Languages and Transformation Engines) were used to provision a modelling environment for the construction, visualization and transformation of systems based on the notion of OCS. An initial mechanism was then established, and a prototype built for system understanding, verification and validation.