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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

Incremental Aspect Model Learning on Streaming¡@Documents

Wu, Cheng-Wei 16 August 2010 (has links)
Owing to the development of Internet, excessive online data drive users to apply tools to assist them in obtaining desired and useful information. Information retrieval techniques serve as one of the major assistance tools that ease users¡¦ information processing loads. However, most current IR models do not consider processing streaming information which essentially characterizes today¡¦s Web environment. The approach to re-building models based on the full knowledge of data at hand triggered by the new incoming information every time is impractical, inefficient, and costly. Instead, IR models that can be adapted to streaming information incrementally should be considered under the dynamic environment. Therefore, this research is to propose an IR related technique, the incremental aspect model (ISM), which not only uncovers latent aspects from the collected documents but also adapts the aspect model on streaming documents chronologically. There are two stages in ISM: in Stage I, we employ probabilistic latent semantic indexing (PLSI) technique to build a primary aspect model; and in Stage II, with out-of-date data removing and new data folding-in, the aspect model can be expanded using the derived spectral method if new aspects significantly exist. Three experiments are conducted accordingly to verify ISM. Results from the first two experiments show the robust performance of ISM in incremental text clustering tasks. In Experiment III, ISM performs the task of storylines tracking on the 2010 Soccer World Cup event. It illustrates ISM¡¦s incremental learning ability to discover different themes around the event at any time. The feasibility of our proposed approach in real applications is thus justified.
162

Concept Extraction With Change Detection From Navigated Information

Lin, Tzu-hsiang 07 July 2005 (has links)
To manage the information flood in the Internet, we usually navigate specific information using the provided search engines. Search engines are convenient but with limited functions. For example, it is impractical and impossible to browse through the entire collected information for us to gain an overall picture about what the navigated information stands for. To do so, we need an appropriate approach to automatically extracting concepts from the navigated information to assist users to easily and quickly gain the primary understanding toward a topic that interests users. In this research, we propose an approach to extracting concepts from the navigated web information and detecting the concept changes over time. It basically includes two stages. In the first stage, information is decomposed into paragraphs and they are clustered with key terms identified through the aid of latent semantic indexing method. Concepts are represented in the form of paragraph summary and associated key terms, which allows the user to easily comprehend what they describe. The second stage is to adaptively modify the concept structure to detect concept changes. With new information added, the concepts could be merging, splitting, or even emerging with time. Three experiments are conducted in this research to verify the proposed approach. Results of the first and second experiments show both high recall and high precision that matches the predefined concept categories. The last one is an illustrated real case application on the tsunami event. It shows that we can easily grasp different concepts of the tsunami reports and realize their changes by using our approach. The feasibility of employing our approach is thus justified.
163

Design of Document-Driven Decision Support Systems

Liu, Yu-liang 10 February 2006 (has links)
Documents are records of activities and related knowledge generated from organizational operations. With the trend of more and more documents being stored in the digital form, how to manage this knowledge has become an important issue. The first step is to manage knowledge is to activate the content of knowledge. These documents stored in an organization can not only be retrieved for future reference but also be analyzed to assist managers in making the right decision. Therefore, it is important for a organization to develop document-driven DSS that can discover useful knowledge from a large amount of documents in an organization. Most previous research on document management are focused on the indexing, retrieval and mining of documents, few applications have investigate how this technology can be used to construct knowledge for decision support. The purpose of this research is to propose an approach for developing document-driven DSS. In particular, the research proposes a methodology that combines ontology, indexing, and information retrieval technology to develop event scheme that can be used as a basis for the document-driven DSS. A prototype system has been designed to analyze documents collected from a journal ranking exercise to demonstrate the feasibility of the proposed approach.
164

A Study on Manufacturing Errors and Positioning Accuracy of Curvic Couplings

Lin, Cheng-Ta 04 July 2000 (has links)
Curvic couplings have been widely applied in industry and almost can be seen in the index table. Following the development of the precision machine industry, except the manufacturing precision, the positioning accuracy is also concerned to meet the demands for curvic couplings. The aim of this thesis is to investigate on manufacturing errors and positioning accuracy of curvic couplings. Discuss the geometric and indexing characteristics of curvic couplings firstly. In the meantime, the new parameter tooth surface of curvic couplings is derived by tooth generating theory. Than, mathematical models are established to simulate curvic couplings at present that are manufactured by grinding machine with different setting errors. Secondly, the practical examples based on the effects of elemental error on the manufacturing error are investigated. Finally, an experimental apparatus is built to measure the actual positioning accuracy of curvic couplings at different input speeds.
165

A Study of the Torque Compensating Phase on the Positioning Accuracy of Indexing Tables

Ho, Sheng-Ying 05 July 2001 (has links)
Recently, many industries pursue the goal of automatic high-speed assembly and manufacturing. So how to meet the requirement of high-precision and high-speed automatic assembly equipment is an important issue. In automatic assembly equipment, the high-speed indexing devices have been widely used because of their features of high precision, no backlash, and compactness. With increasing operating speeds, the problems of shortage of motor power, poor indexing accuracy, vibration, and noise shall be solved. The torque compensation mechanism that is to be developed here is applied to keep motors operating at constant speeds by compensating the required torque. In previous researches, the researchers all devote to study torque compensation based on synchronous time chart. In this paper, it is aimed at compensation of the time control chart according the point of view of energy and the system model is built to simulate dynamic response of the system. Through the results of simulation and experiment, we will discover the relations between the compensation time chart and parameters about the high-speed indexing devices. It is expected to improve the precision of indexing devices according to those effective compensation time control charts.
166

An ACGT-Words Tree for Efficient Data Access in Genomic Databases

Hu, Jen-Wei 25 July 2003 (has links)
Genomic sequence databases, like GenBank, EMBL, are widely used by molecular biologists for homology searching. Because of the increase of the size of genomic sequence databases, the importance of indexing the sequences for fast queries grows. The DNA sequences are composed of 4 base pairs, and these genomic sequences can be regarded as the text strings. Similar to conventional databases, there are some approaches use indexes to provide efficient access to the data. The inverted-list indexing approach uses hashing to store the database sequences. However, the perfect hashing function is difficult to construct, and the collision in a hash table may occur frequently. Different from the inverted-list approach, there are other data structures, such as the suffix tree, the suffix array, and the suffix binary search tree, to index the genomic sequences. One characteristic of those suffix-tree-like data structures is that they store all suffixes of the sequences. They do not break the sequences into words. The advantage of the suffix tree is simple. However, the storage space of the suffix tree is too large. The suffix array and the suffix binary search tree reduce more storage space than the suffix tree. But since they use the binary searching technique to find the query sequence, they waste too much time to do the search. Another data structure, the word suffix tree, uses the concept of words and stores partial suffixes to index the DNA sequence. Although the word suffix tree reduces the storage space, it will lose information in the search process. In this thesis, we propose a new index structure, ACGT-Words tree, for efficiently support query processing in genomic databases. We define the concept of words which is different from the word definition given in the word suffix tree, and separate the DNA sequences stored in the database and in the query sequence into distinct words. Our approach does not store all of the suffixes in the database sequences. Therefore, we need less space than the suffix tree approach. We also propose an efficient search algorithm to do the sequence match based on the ACGT-Words tree index structure; therefore, we can take less time to finish the search than the suffix array approach. Our approach also avoids the missing cases in the word suffix tree. Then, based on the ACGT-Words tree, we propose one improved operation for data insertion and two improved operations for the searching process. In the improved operation for insertion, we sort the ACGT-Words generated and then preprocess them before constructing the tree structure. In the two improved operations, we can provide better performance when the query sequence satisfies some conditions. The simulation results show that the ACGT-Words tree outperforms the suffix tree and the suffix array in terms of storage and processing time, respectively. Moreover, we show that the improved operations in the ACGT-Words tree also require shorter time to construct or search than the original processes or the suffix array.
167

A Unique-Bit-Pattern-Based Indexing Strategy for Image Rotation and Reflection in Image Databases

Yeh, Wei-horng 16 June 2008 (has links)
A symbolic image database system is a system in which a large amount of image data and their related information are represented by both symbolic images and physical images. Spatial relationships are important issues for similarity-based retrieval in many image database applications. How to perceive spatial relationships among the components in a symbolic image is an important criterion to find a match between the symbolic image of the scene object and the one being store as a modal in the symbolic image database. With the popularity of digital cameras and the related image processing software, a sequence of images are often rotated or flipped. That is, those images are transformed in the rotation orientation or the reflection direction. A robust spatial similarity framework should be able to recognize image variants such as translation, scaling, rotation, and arbitrary variants. Current retrieval by spatial similarity algorithms can be classified into symbolic projection methods, geometric methods, and graph-matching methods. Symbolic projection could preserve the useful spatial information of objects, such as width, height, and location. However, many iconic indexing strategies based on symbolic projection are sensitive to rotation or reflection. Therefore, these strategies may miss the qualified images, when the query is issued in the orientation different from the orientation of the database images. To solve this problem, researchers derived the rule of the change of spatial relationships in image transformation, and proposed a function to map the spatial relationship to its related transformed one. However, this mapping consists of several conditional statements, which is time-consuming. Thus, in this dissertation, first, we classify the mapping into three cases and carefully assign a 16-bit unique bit pattern to each spatial relationship. Based on the assignment, we can easily do the mapping through our proposed bit operation, intra-exchange, which is a CPU operation and needs only the complexity of O(1). Moreover, we propose an efficient iconic index strategy, called Unique Bit Pattern matrix strategy (UBP matrix strategy) to record the spatial information. In this way, when doing similarity retrieval, we do not need to reconstruct the original image from the UBP matrix in order to obtain the indexes of the rotated and flipped image. Conversely, we can directly derive the index of the rotated or flipped image from the index of the original one through bit operations and the matrix manipulation. Thus, our proposed strategy can do similarity retrieval without missing the qualified database images. In our performance study, first, we analyze the time complexity of the similarity retrieval process of our proposed strategy. Then, the efficiency of our proposed strategy according to the simulation results is presented. We show that our strategy outperforms those mapping strategies based on different number of objects in an image. According to the different number of objects in an image, the percentage of improvement is between 13.64% and 53.23%.
168

WebDoc an automated Web document indexing system /

Tang, Bo. January 2002 (has links)
Thesis (M.S.)--Mississippi State University. Department of Computer Science. / Title from title screen. Includes bibliographical references.
169

An Examination of Authority in Social Classification Systems

Feinberg, Melanie January 2006 (has links)
Champions of social classification praise its flexible and collaborative nature, in contrast to the rigidity and authoritarianism that they see in traditional classificative structures (such as Kroski, 2005; Shirky, 2005c; Merholz, 2004). In the view of these writers, social classification applications such as the photo storage Web site Flickr and the Web bookmarks manager del.icio.us are both democratic, incorporating the participation of all Web users, and emergent, changing rapidly in response to new content. On the other hand, traditional methods for organizing information, particularly those that involve hierarchy, are seen as exclusive, because they may not represent all usersâ viewpoints, and imprecise, because they cannot be easily adapted for the rapid pace of content development engendered by Web publishing. Two claims appear to underlie these descriptions of social classification. One, that the goal of classification is to identify and locate items based on a personal sense of appropriate categorization, and two, that, if enough other users index (or tag) items according to their own personal ideas of appropriate categorization, then all possibilities will be represented, and both searching and browsing will be facilitated. This paper will evaluate these claims, particularly in regards to the role and nature of authority in organizational schemes, and the intersection of authority with an organizational schemeâ s purpose. I consider these issues for three services often associated with social classification systems: * Indexing of personal collections. * Sharing of indexed personal collections. * Merging of personal collections into a group-indexed aggregate collection. The bookmarks manager del.icio.us is the primary example of a social classification system used throughout this paper.
170

Structure and form of folksonomy tags: The road to the public library catalogue

Spiteri, Louise 06 1900 (has links)
Folksonomies have the potential to add much value to public library catalogues by enabling clients to: store, maintain, and organize items of interest in the catalogue using their own tags. The purpose of this paper is to examine how the tags that constitute folksonomies are structured. Tags were acquired over a thirty-day period from the daily tag logs of three folksonomy sites, Del.icio.us, Furl, and Technorati. The tags were evaluated against section 6 (choice and form of terms) of the National Information Standards Organization (NISO) guidelines for the construction of controlled vocabularies. This evaluation revealed that the folksonomy tags correspond closely to the NISO guidelines that pertain to the types of concepts expressed by the tags, the predominance of single tags, the predominance of nouns, and the use of recognized spelling. Potential problem areas in the structure of the tags pertain to the inconsistent use of the singular and plural form of count nouns, and the incidence of ambiguous tags in the form of homographs and unqualified abbreviations or acronyms. Should library catalogues decide to incorporate folksonomies, they could provide clear guidelines to address these noted weaknesses, as well as links to external dictionaries and references sources such as Wikipedia to help clients disambiguate homographs and to determine if the full or abbreviated forms of tags would be preferable.

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