Browsing by Subject "Information storage and retrieval systems"
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Item A homogeneous temporal extension of QUEL(1984-12) Vaishnav, Jay H.The role of time in databases is being studied by researchers increasingly. Temporal query languages have been proposed for a number of historical database models. This thesis contains a survey of some important temporal relational database models and their query languages. A new temporal query language is proposed for a temporal database model.Item An automated police information system for a small town(Texas Tech University, 1972) Parsa, John HooshangSince the first English colonists in the early 17th Century, expanding civilization and environmental quality have often been in direct conflict. By the mid-1800's reduced wildlife populations, declining natural resources, and vanishing wilderness settings had become problems of such magnitude that a significant number of sensitive citizens began to call for conservation. The environmental movement as we know it today had its roots in the efforts of men such as John Wesley Powell, George Perkins Marsh, Gifford Pinchot and John Muir to foster a sense of stewardship toward the natural environment. Mounting scientific evidence during the 1960's of human health effects and ecological damage resulting from anthopogenic pollutants gave rise to a spate of environmental legislation designed to protect human health and welfare, as well as enhance environmental quality. One of the most important pieces of environmental legislation, to date, is the National Environmental Policy Act (NEPA) of 1969. It not only established a national policy of commitment to maintaining environmental quality and promoting harmony between man and nature, but also set up the Council on Environmental Quality and instituted requirements for Environmental Impact Statements (EISs) for major federal actions significantly affecting the environment. (A va of techniques are currently available for determining the impact of proposed action on the environment; however, a common shortcoming of these methodologies is their inability to adequately predict and assess changes in the socioeconomic environment As increasing emphasis is placed by planners and decision-makers on the human factors associated with a proposed project, better methods for establishing the critical socioeconomic indicators and measuring attribute changes will become imperative. ^At the present time, there is no standard, reliable methodology for analyzing the socioeconomic implications of contemplated programs.Item Antecedents to systems development: beliefs of information systems specialists and users(Texas Tech University, 1994-12) Havelka, DouglasThis research project was undertaken to investigate an area of information systems development that had received sparse attention: users' and IS specialists' beliefs that may influence their interaction during the information requirements determination process. A general User/IS Specialist Interaction Framework was presented that postulates that the interaction between users and IS specialists during information systems development can be conceptualized as a set of behaviors. These behaviors are derived from: (1) users' and IS specialists' beliefs toward these behaviors; and (2) extemal factors that moderate the intended behaviors. In essence, the beliefs and extemal factors are antecedents to user/IS specialist interaction during development. Based on these propositions, a set of research questions directed at discovering the beliefs of users and IS specialists and the differences between these beliefs toward the information requirements determination process was developed. A two-stage empirical study was conducted to address these questions. The results of this work can be summarized as follows. First, it appears that users as a group, despite differences in experience, training, etc., do have a common set of beliefs toward the critical productivity factors influencing the information requirements determination process. Second, it appears that IS specialists as a group, despite differences in experience, training, and methods used, also have a common set of beliefs toward the critical productivity factors influencing information requirements determination. Third, the empirical evidence suggests that overall users and IS specialists disagree with regard to the relative level of importance of the critical productivity factors identified. Fourth, it appears that the beliefs of users toward the relative importance of several of the critical productivity factors for information requirements determination are significantly related to their level of involvement with the developed system. Fifth, it does not appear that the beliefs of users toward the relative importance of critical productivity factors for infomiation requirements determination are necessarily significantly related to their level of satisfaction with the developed system.Item Characterication of wire delays in large SRAM arrays(Texas Tech University, 2004-05) Brackett, BenjaminAs the size of on-chip caches in continues to increase, wire delays become a more dominant factor in limiting the speed of the cache. The fact that the wire length for each bit in the array is different causes a significant speed delta between the fastest and slowest bits in a given array. The speed difference between the fastest and slowest bit cells causes a reliability concern if the entire array is tested at a single speed. This paper will quantify the speed difference between the fastest and slowest bits in the L2 cache of the Ultrasparc IV processor, and examine the possible reliability impacts of this difference.Item Energy-aware embedded media processing: customizable memory subsystems and energy management policies(2004) Ramachandran, Anand; Jacome, Margarida F.The design of energy-efficient data memory architectures for embedded system platforms has received considerable attention in recent years. In this dissertation we propose a special-purpose data memory subsystem, called Xtream-Fit, targeted to streaming media applications executing on both generic uniprocessor embedded platforms and powerful SMT-based multi-threading platforms. We empirically demonstrate that Xtream-Fit achieves high energydelay efficiency across a wide range of media devices, from systems running a single media application to systems concurrently executing multiple media applications under synchronization constraints. Xtream-Fit’s energy efficiency is predicated on a novel task-based execution model that exposes/enhances opportunities for efficient prefetching, and aggressive dynamic energy conservation techniques targeting on-chip and off-chip memory components. A key novelty of Xtream-Fit is that it exposes a single customization parameter, thus enabling a very simple and yet effective design space exploration methodology to find the best memory configuration for the target application(s). Extensive experimental results show that Xtream-Fit reduces energy-delay product substantially – by 32% to 69% – as compared to ‘standard’ general-purpose memory subsystems enhanced with state of the art cache decay and SDRAM power mode control policies.Item High capacity data hiding system using BPCS steganography(Texas Tech University, 2003-12) Srinivasan, YeshwanthNot availableItem Learning for information extraction: from named entity recognition and disambiguation to relation extraction(2007-08) Bunescu, Razvan Constantin, 1975-; Mooney, Raymond J. (Raymond Joseph)Information Extraction, the task of locating textual mentions of specific types of entities and their relationships, aims at representing the information contained in text documents in a structured format that is more amenable to applications in data mining, question answering, or the semantic web. The goal of our research is to design information extraction models that obtain improved performance by exploiting types of evidence that have not been explored in previous approaches. Since designing an extraction system through introspection by a domain expert is a laborious and time consuming process, the focus of this thesis will be on methods that automatically induce an extraction model by training on a dataset of manually labeled examples. Named Entity Recognition is an information extraction task that is concerned with finding textual mentions of entities that belong to a predefined set of categories. We approach this task as a phrase classification problem, in which candidate phrases from the same document are collectively classified. Global correlations between candidate entities are captured in a model built using the expressive framework of Relational Markov Networks. Additionally, we propose a novel tractable approach to phrase classification for named entity recognition based on a special Junction Tree representation. Classifying entity mentions into a predefined set of categories achieves only a partial disambiguation of the names. This is further refined in the task of Named Entity Disambiguation, where names need to be linked to their actual denotations. In our research, we use Wikipedia as a repository of named entities and propose a ranking approach to disambiguation that exploits learned correlations between words from the name context and categories from the Wikipedia taxonomy. Relation Extraction refers to finding relevant relationships between entities mentioned in text documents. Our approaches to this information extraction task differ in the type and the amount of supervision required. We first propose two relation extraction methods that are trained on documents in which sentences are manually annotated for the required relationships. In the first method, the extraction patterns correspond to sequences of words and word classes anchored at two entity names occurring in the same sentence. These are used as implicit features in a generalized subsequence kernel, with weights computed through training of Support Vector Machines. In the second approach, the implicit extraction features are focused on the shortest path between the two entities in the word-word dependency graph of the sentence. Finally, in a significant departure from previous learning approaches to relation extraction, we propose reducing the amount of required supervision to only a handful of pairs of entities known to exhibit or not exhibit the desired relationship. Each pair is associated with a bag of sentences extracted automatically from a very large corpus. We extend the subsequence kernel to handle this weaker form of supervision, and describe a method for weighting features in order to focus on those correlated with the target relation rather than with the individual entities. The resulting Multiple Instance Learning approach offers a competitive alternative to previous relation extraction methods, at a significantly reduced cost in human supervision.Item Query languages for a heterogeneous temporal database(Texas Tech University, 1986-08) Yeung, Chung-singTime is an important dimension in databases. In a conventional database, out-of-ate information is usually replaced by current information to keep the database up-to-date. In many applications, discarding old information is inappropriate. A temporal database incorporates the notion of time. Objects in a temporal database are not deleted. On the contrary, they are retained and time-stamped to indicate their periods of existence in the real world. Over the last few years, a number of temporal relational database models have been proposed. This thesis reviews these models and proposes a heterogeneous model. We also develop a relational algebra and a tuple calculus for this model and prove their equivalence. The model and query languages capture the concept of "always" and "sometime" in natural language. In addition, they provide powerful operations with respect to temporal properties of information contained in tuples. When compared to existing approaches, fewer operations are needed to express complex queries. As a result, fewer intermediate scratch pads will be used during query execution. Consequently the space and time complexity introduced by the temporal dimension in temporal databases will be reduced.Item Rock star: a computer modeling and animation portfolio(Texas Tech University, 2004-05) Davis, Brett AllanNot available