Thesis (M.B.A.)--University of Hong Kong, 1994. / Includes bibliographical references (leaves 84-85).

Most of the wastes produced in the developing countries are low- and intermediate-level wastes. These wastes are initially stored on-site. Since applications using of the radioactive materials is increasing, in some countries, the radioactive wastes are accumulating to the point that the initial on-site storage has to be expanded. In order to increase interim storage capacity, existing capacity must be increased or replaced with a new permanent facility. The waste management system cost must be considered to achieve the most cost effectiveness. The management of radioactive waste includes every step in the system from the waste generator to the final disposal. The major costs in the waste system are: processing costs, transportation costs, and burial costs. However, modification of one step to reduce its cost may impact other costs in the system and even increase total costs as well. Computer models have been developed that simulate the entire system so that interactive may be evaluated to determine for estimating the generic total waste system cost and average unit disposal cost. The radioactive waste materials produced in Thailand are used as input data to test the models. The preliminary site screening and site design study to identify the potentially suitable site areas are also performed in this study. The sensitivity analyses obtained from the disposal model show that the rate of return or interest rate, the operating cost and the capital costs affect the disposal unit cost. The development, and postoperating period do not affect on the disposal unit cost. The results obtained from system cost model show that type of waste, volume reduction factor, and treatment technology affect the waste management system cost.

published_or_final_version / Real Estate and Construction / Master / Master of Science in Construction Project Management

Contextual experience with the practical application of accounting standards is important for independent audit committee members to effectively monitor managers’ financial reporting estimates and the audits of those estimates. Basic knowledge of accounting standards can be acquired by reading public documents and some degree of information regarding firm-specific application of standards can be obtained from public disclosures. However, real-world, contextual experience may best be obtained through performing or monitoring the reporting tasks themselves. This dissertation investigates how a firm’s (focal firm) financial reporting monitoring activities are affected by its audit committee members’ contextual experiences gained through connections, either as managers or audit committee members, with other firms (links or interlocks). I specifically estimate whether contextual experience with significant judgments and estimates, measured as interlocks with firms that likely performed extensive impairment analyses in the prior year (distressed firms), affects the likelihood of focal firm decisions to write off goodwill after controlling for economic indicators of impairment, managerial incentives to misreport, and ability of managers to exercise discretion. I find that the likelihood of write-off is significantly greater for firms with links to distressed firms than firms without links, consistent with audit committee contextual experience influencing financial reporting outcomes. The distressed firm interlock effect is significantly greater when the contextual experience at the linked firm is in the performance of estimates as a manager in contrast to the monitoring of estimates as an audit committee member. However, in a subset of large firms with ExecuComp data, I find that the overall probability of write-off is decreasing across quartiles of managerial incentives to misreport and received interlocks are only marginally significant in the second quartile, indicating that contextual experience may not be an effective monitoring mechanism when managerial incentives to misreport are high. Combined results suggest that contextual experiences obtained through audit committee network associations do affect focal firm financial reporting outcomes and are most influential when the contextual experience is as a manager, rather than a monitor. However, such monitoring mechanisms appear to be primarily imitative and may not be effective deterrents against managerial misreporting at large firms when managerial equity-based incentives are strong. / text

The main part of the thesis is set to review and extend the theory of the so called Strichartztype estimates. We present a new viewpoint on the subject according to which our primary goal is the study of the (endpoint) inhomogeneous Strichartz estimates. This is based on our result that the class of all homogeneous Strichartz estimates (understood in the wider sense of homogeneous estimates for data which might be outside the energy class) are equivalent to certain types of endpoint inhomogeneous Strichartz estimates. We present our arguments in the abstract setting but make explicit derivations for the most important dispersive equations like the Schr¨odinger , wave, Dirac, Klein-Gordon and their generalizations. Thus some of the explicit estimates appear for the first time although their proofs might be based on ideas that are known in other special contexts. We present also several new advancements on well-known open problems related to the Strichartz estimates. One problem we pay a special attention is the endpoint homogeneous Strichartz estimate for the kinetic transport equation (and its generalization to estimates with vector-valued norms.) For example, this problem was considered by Keel and Tao [30], but at the time the authors were not able to resolve it. We also fall short of resolving that problem but instead we prove a weaker version of it that can be useful for applications. Moreover, we also make a conjecture and give a counterexample related to that problem which might be useful for its potential resolution. Related to the latter is the fact that we now primarily use complex interpolation in the proof of the homogeneous and the inhomogeneous Strichartz estimates, which produces more natural norms in the vector-valued and the abstract setting compared to the real method of interpolation employed in earlier works. Another important direction of the thesis is to study the range of validity of the Strichartz estimates for the kinetic transport equation which requires a separate and more delicate approach due to its vector-valued dispersive inequality and a special invariance property. We produce an almost optimal range of estimates for that equation. It is an interesting fact that the failure of certain endpoint estimates with L∞ or L1-space norms can be shown on characteristics of Besicovitch sets. With regard to applications of these estimates we demonstrate for the first time in the context of a nonlinear kinetic system (the Othmer-Dunbar-Alt kinetic model of bacterial chemotaxis) that its global well-posedness for small data can be achieved via Strichartz estimates for the kinetic transport equation. Another new development in the thesis is connected to the question of the global regularity of the Dirac-Klein-Gordon system in space dimensions above one for large initial data. That question was instigated in the 1970’s by Chadam and Glassey [12, 13, 22] and although a great number of mathematicians have made contributions in the past 30 years, we, together with the independent recent preprint by Gr¨unrock and Pecher [24], present the first global result for large data. In particular, we prove that in two space dimensions the system has spherically symmetric solutions for all time if the initial data is spherically symmetric and lies in a certain regularity class. Our result is achieved via new inhomogeneous Strichartz estimates for spherically symmetric functions that we prove in the abstract setting and in particular for the wave equation. We make a number of other lesser improvements and generalizations in relation to the Strichartz estimates that shall be presented in the main body of this text.

In this article we construct the fundamental solutions for the wave equation arising in the de Sitter model of the universe. We use the fundamental solutions to represent solutions of the Cauchy problem and to prove the Lp − Lq-decay estimates for the solutions of the equation with and without a source term.

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Ephemeral streamflow infiltration through alluvial channels has been identified as an important source of aquifer replenishment in arid and semi-arid environments. In this dissertation, two field methods were developed for monitoring streamflow timing in ephemeral stream channels. The first streamflow timing method exploits differences in the advective and conductive thermal transport mechanisms during the presence and absence of streamflow. The second method of streamflow timing utilized the relationship between soil water content and electrical conductance. Electrical resistance sensors were designed to detect saturated soil conditions and thus to infer streamflow timing during periods of saturation. Both methods were field-tested in Rillito Creek, Tucson, Arizona. The electrical resistance method proved more suitable than the temperature method because it was not depth dependent and was able to more accurately infer streamflow timing with less data post processing. Transient and steady state infiltration fluxes were simulated in a coarse-grained alluvial channel to determine the relative contribution the onset of streamflow provides to potential recharge. Water content, temperature, and pore pressure measurements were incorporated into a variably saturated heat and fluid transport model to simulate infiltration. Infiltration fluxes at the onset of streamflow were about 2-3 orders of magnitude higher than steady state fluxes and were inversely proportional to antecedent water content. The time duration from the onset of streamflow to steady-state infiltration ranged from 1.8 to 20 hours. Two transient and steady state periods were observed indicating a lower permeable layer at depth. During steady state periods, infiltration fluxes averaged 0.33 meters per day and ranged from 0.14 to 0.45 meters per day. A long-term decline was observed in all three events. Higher frequency diurnal and episodic changes were prompted by fluctuations in atmospheric temperature and discharge. The simulated steady state values were consistent with the effective vertical conductivity values (0.22 meters per day) of an underlying less permeable layer. The average contribution from the cumulative transient infiltration for the events was approximately 18 percent. Therefore, it is apparent that potential recharge calculations for alluvial channels that do not consider infiltration during the onset transient period may underestimate the true potential for recharge.

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published_or_final_version / Civil and Structural Engineering / Master / Master of Philosophy