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ProQuest (500)

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CSDL gồm 500 luận án được chuyển nhượng tác quyền bởi ProQuest Information and Learning Company. CSDL này chỉ phục vụ cho Cán bộ ĐHQG TP.HCM và các trường thành viên. Để đọc nội dung toàn văn, xin liên hệ:
Phòng Phục vụ Độc giả, Thư viện Trung tâm - ĐHQG TP.HCM
,
ĐT: 37242181, ext.2935 hoặc E-Mail: phucvu@vnuhcm.edu.vn

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Item 1 - 20 [/500]

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  • Authors: Boicu, Cristina E. (2007)

  • Our research addresses the problem of developing knowledge-based agents that incorporate the knowledge of subject matter experts. Our approach is to develop a learning and problem solving agent, which can be directly taught by a subject matter expert by explaining it how to solve specific problems, and by critiquing its attempts to solve new problems. Because the accuracy of the agent's reasoning depends on the rules from its knowledge base, the process of rule improvement is very important. This dissertation presents an integrated set of methods to assist a subject matter expert in refining the rules from an agent's knowledge base, to incorporate his problem solving expertise. This d...

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  • Authors: Pradhan, Sameer S. (2006)

  • The natural language processing community has recently experienced a growth of interest in domain independent semantic role labeling. the process of semantic role labeling entails identifying all the predicates in a sentence, and then, identifying and classifying sets of word sequences, that represent the arguments (or, semantic roles) of each of these predicates. In other words, this is the process of assigning a WHO did WHAT to WHOM, WHEN, WHERE, WHY, HOW etc. structure to plain text, so as to facil itate enhancements to algorithms that deal with various higher-level natural language processing tasks, such as - information extraction, question answering, summarization, machine tr...

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  • Authors: Gowing, Glyn Thomas (2007)

  • Computer networks continue to be the targets of numerous types of attacks, which can expose sensitive data or simply deny service to legitimate users. Current intrusion detection technologies utilize signature bases that allow them to rapidly and accurately identify known attacks. This, however, leaves them vulnerable to previously unknown attacks. An adaptive approach, capable of recognizing novel attacks, is warranted. The proposed research presents an adaptive agent-based intrusion detection sys¬tem. The approach is innovative in several respects: the agents self-organize into a scale-free peer-to-peer network, emergent behavior is facilitated by allowing simple communication betw...

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  • Authors: Horling, Bryan (2006)

  • As the scale and scope of distributed and multi-agent systems grow, it becomes increasingly important to design and manage the participants’ interactions. The potential for bottlenecks, intractably large sets of coordination partners, and shared bounded resources can make individual and high-level goals difficult to achieve. To address these problems, many large systems employ an additional layer of structuring, known as an organizational design, that assigns agents particular and different roles, responsibilities and peers. These additional constraints can allow agents to operate effectively within a large-scale system, with little or no sacrifice in utility. Different design...

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  • Authors: Kang, Dong-Hee (2006)

  • High concentrations of cyanide in soil can result from contamination by road salt, electroplating waste, and residuals from manufactured gas plant sites. The most toxic species is “free” cyanide (CN_, HCN), but this form is generally rare in contaminated soil and groundwater. Iron cyanides are often predominant in environmental samples and have low toxicity. Unfortunately, free cyanides are the thermodynamically favorable species in solution, and degradation of iron cyanide compounds to the free cyanides can be accelerated by sunlight and microorganisms. There were two objectives of this research project. The first objective was to investigate the potential for phytoremediation of ...

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  • Authors: Murthy, Tejas Gorur S. (2006)

  • The thesis reports on experimental research on the static undrained response of silty and clayey sands. The purpose of this testing program was to understand the stress-strain response of sands with small percentages of fines. With this objective in sight, the testing program involved understanding and delineating the effect of four variables: density of the soil, percentage of fines in the sand matrix, plasticity of the fines, and the mode of deformation only under isotropically consolidated, and static loading triaxial conditions. Four characteristic states were identified in the undrained response of the soils investigated: the undrained instability state, quasi-steady state, phase...

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  • Authors: Lee, Sang-Ho (2006)

  • The doctoral research is a study of soil filtration by geotextile fabrics, with the ultimate objective of improving design and long-term performance of underdrain systems in highways. The experimental investigation was conducted in the laboratory using the best available techniques, the Flexible Wall Gradient Ratio Test and the Rapid Retention Test, in order to assess soil-filter compatibility and monitor geotextile clogging, for a range of materials and testing conditions. Field information was also collected and samples from highway reconstruction project were examined for their long-term performance. The main findings from these experiments relate to the influence of such factors ...

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  • Authors: Pattnaik, Rashmi Ranjan (2006)

  • Due to the availability of a wide variety of repair materials in the concrete repair industry, with a wide range of physical and mechanical properties, selection of repair material for a particular repair of concrete is challenging. Previous studies and the available literature indicate that the failure of concrete repairs is mainly due to improper selection of repair material based on repair material properties, without investigating compatibility between repair material and substrate concrete. The compatibility between repair material and substrate concrete exists when the composite section of repair material and substrate concrete withstands all stresses induced by applied load und...

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  • Authors: Kim, Yeonjoo (2006)

  • The soil moisture-vegetation-precipitation feedback at the seasonal time scale can play a critical role in the North American seasonal climate. To investigate such feedback mechanisms, we first incorporate into the land model (CLM) the vegetation phenology scheme, which can simulate the seasonal variation of vegetation in response to hydrometorological conditions. The modified land model is validated against the remotely-sensed MODIS LAI observations. Using the coupled land-atmosphere model CAM-CLM that includes the modified land model, a series of ensemble simulations are performed to examine how initial soil moisture anomalies influence the subse¬quent precipitation at the seasonal ...

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  • Authors: Gu, Xianyue (2006)

  • Pulsed power refers to a technology that is suited to drive applications requiring very large power pulses in short bursts. Its recent emerging applications in biology demand compact systems with high voltage electric pulses in nanosecond time range. The required performance of a pulsed power system is enabled by the combined efforts in its design at three levels: efficient and robust devices at the component level, novel circuits and architecture at the system level, and effective interface techniques to deliver fast pulses at the application level. At the component level we are concerned with the power capability of switches and the energy storage density of capacitors. We compar...

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  • Authors: Kang, Chang Woo (2006)

  • Coarse-grained, antifuse-based FPGAs have emerged as a compelling technology to minimize the performance gaps between FPGAs and ASICs in area, speed, and power dissipation. As the FPGA architectures prefer large, programmable logic blocks, efficient clustering algorithms are vital to make use of the benefits from those advanced architectures. Circuit clustering is an important technique for coarse-grained FPGAs. First, clustering can reduce the complexity of large circuit designs by a significant factor. Second, clustering can improve the quality of the results of other operations such as placement and routing. In this dissertation, clustering techniques for area, delay, and power d...

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  • Authors: Rajagopalan, Sundaram (2006)

  • Forensic analysis is the process of understanding, re-creating, and analyzing arbitrary events that have previously occurred. It seeks to answer such questions as how an intrusion occurred, what an attacker did during an intrusion, and what the effects of an attack were. Currently the field of computer forensics is largely ad hoc. Data is generally collected because applications log it for debugging purposes or because someone thought it to be important. Practical forensic analysis has traditionally traded off analyzability against the amount of data recorded. Recording less data puts a smaller burden both on computer systems and on the humans that analyze them. Not recording enough ...

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  • Authors: Shay, Daniel Travis (2006)

  • The synthesis and structural characterization of imido ligated cobalt complexes that employ the sterically hindered hydrotris(3-`Bu-5-Me-pyrazolyl)borate ligand, i. e., TptBu,MeCoNR (R = Me, Et, `Bu, Ad) have been accomplished. These terminal imido complexes possess relatively short Co-N bond distances in the range of 1.64-1.67 A, indicating a multiple bond to the metal. Reactivity studies have been undertaken with a variety of substrate ranging from protonation using acids such as HC1 and lutidinium-BARF (BARF = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) to ligand transfer of the imido fragment to carbon monoxide. Kinetic studies of the thermal decomposition of Tp'Bu,MeCoN...

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  • Authors: Williamson, Kurt Elliott (2006)

  • The importance of viruses in aquatic ecosystems has been established over the past decade. By contrast, the abundance and distribution of viruses in soils is almost completely unknown. An essential first step in any investigation of viruses in soil is evaluation of viral recovery methods suitable for subsequent cultivation-independent analyses. A comparison of four common elution buffers indicated that potassium citrate eluted the highest numbers of viruses from soils (1.5 X 108 gram dry weight-1 grand mean), but specific soil-eluant combinations posed significant problems to enumeration by epifluorescence microscopy. Thus, the measurement of phage abundance in soils varied with both ...

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  • Authors: Elifantz, Hila (2006)

  • Heterotrophic bacteria are important participants in the global carbon cycle as they process about 50% of the fixed carbon in the oceans. Since the amount of primary production in the ocean is equal to that in terrestrial environments, the need to understand these processes is obvious. Various measurements are used to assess the amount of carbon that is processed through bacteria, including bacterial production, bacterial respiration, dissolved organic matter (DOM) concentrations and fluxes. However, none of these methods reveal which bacterial groups use specific compounds in the DOM pool. The aim of this dissertation was to address some of these issues. Microautoradiography combine...

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  • Authors: Villalobos, Rodney V. (2006)

  • Faced with uncertain data and an unpredictable return on computational tool investment, researchers are opting for laboratory studies over in silico (computer based) studies. This study addressed the lack of efficiency in identifying motifs (biologically significant amino sequences) in deoxyribonucleic acid (DNA) sequences via naive Bayesian text classification. DNA is a nucleic acid that carries genetic information in cells. A naive Bayesian text classifier is a machine-learning tool that uses automated means of determining metadata and has been used to identify e-mail worms, viruses, and spam. This quantitative study utilized a naive Bayesian text classification algorithm as the pri...

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  • Authors: Kunkel, Curtis J. (2006)

  • In this dissertation, we focus on singular boundary value problems with mixed boundary conditions. We study a variety of types, to all of which we seek a positive solution. We begin by considering the discrete (or difference equation) case, from which we proceed to look at the continuous (or ordinary differential equation) case. In all cases, we make use of a lower and upper solutions method and the Brouwer fixed point theorem in conjunction with perturbation methods to approximate regular problems.

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  • Authors: Zhong, Jie (2006)

  • Many types of auctions are discussed in the literature such as single item auctions, sequential auctions, and combinatorial auctions. Proxy bidding has proven useful in solving iterative auction problems in many real-world auction formats. In this dissertation, I propose a new type of iterative auction called the Simple Combinatorial Proxy Auction. A popular method for solving the iterative proxy auction problems is simulating the incremental bidding decisions of the agents. However, this approach has some disadvantages. In this dissertation, I present a new approach called the Price Trajectory Algorithm to solve iterative auction problems. This approach computes the agents’ allocati...