Digital Commons Network^™

Performance-Based Seismic Engineering Of Low And Medium-Rise Steel Frames, Saeid Rashidi

Dissertations

The performance level of low and medium-rise steel frames designed according to the common force/strength approach of the UBC or NEHRP is determined. Several combinations of soil profile type, lateral-force-resisting system, and frame-member proportioning are included in the designs.

To evaluate the expected damage, nonlinear models of the designed frames are subjected to a number of actual and simulated ground motion accelerograms and appropriate structural response parameters such as, interstory drift, ductility demand, and dissipated hysteretic energy are obtained. In addition, a modified form of Park-Ang damage index is calculated for moment-resisting frames. The seismic performance of the steel frames …

Development And Application Of Dynamic Models For Predicting Transit Arrival Times, Yuqing Ding

Dissertations

Stochastic variations in traffic conditions and ridership often have a negative impact in transit operations resulting in the deterioration of schedule/headway adherence and lengthening of passenger wait times. Providing accurate information on transit vehicle arrival times is critical to reduce the negative impacts on transit users. In this study, models for dynamically predicting transit arrival times in urban settings are developed, including a basic model, a Kalman filtering model, link-based and stop-based artificial neural networks (ANNs) and Neural/Dynamic (ND) models. The reliability of these models is assessed by enhancing the microscopic simulation program CORSIM which can calculate bus dwell and …

Reconfiguration And Tool Path Planning Of Hexapod Machine Tools, Zhenqun Li

Dissertations

Hexapod machine tools have the potential to achieve increased accuracy, speed, acceleration and rigidity over conventional machines, and are regarded by many researchers as the machine tools of the next generation. However, their small and complex workspace often limits the range of tasks they can perform, and their parallel structure raises many new issues preventing the direct use of conventional tool path planning methods. This dissertation presents an investigation of new reconfiguration and tool path planning methods for enhancing the ability of hexapods to adapt to workspace changes and assisting them in being integrated into the current manufacturing environments.

A …

The Influence Of High Performance Matrices On Fracture Behavior Of Concrete, Pusit Lertwattanaruk

Dissertations

Modification of cement matrices by the addition of micro particle pozzolanic materials such as silica fume and fly ash is known to improve the strength of concrete, but its contributions to fracture behavior remains unclear. In this study, the influence of replacing cement by silica fume and fly ash on the cement matrix-coarse aggregate interfacial bond, compressive stress-strain behavior and fracture behavior of concrete is investigated.

While the linear elastic fracture mechanics (LEFM) concept is not appropriate for concrete, a nonlinear fracture model based on the load vs. load-line deflection and the load vs. crack-mouthopening displacement (CMOD) responses of the …

Collaborative Software Agents Support For The Texpros Document Management System, Jrtian Lin

Dissertations

This dissertation investigates the use of active rules that are embedded in markup documents. Active rules are used in a markup representation by integrating Collaborative Software Agents with TEXPROS (abbreviation for TEXt PROcessing System) [Liu and Ng 1996] to create a powerful distributed document management system. Such markup documents with embedded active rules are called Active Documents. For fast retrieval purposes, when we need to generate a customized Internet folder organization, we first define the Folder Organization Query Language (FO-QL) to solve data categorization problems. FO-QL defines the folder organization query process that automatically retrieves links of documents deposited into …

Utilization Of Municipal Solid Waste Incinerator Fly Ash In Cement Mortars, Manaskorn Rachakornkij

Dissertations

Disposal of municipal solid waste has become a major problem in many countries around the world. With the benefits of substantial weight and volume reduction and potential energy recovery, incineration has become a promising municipal solid waste (MSW) management option. Despite the fact that incineration reduces volume and mass of the wastes by as much as 80%, there are still residues to be properly managed. This research is aimed at evaluating the potential of different types of MSWI fly ash from an incineration facility to be used in cement mortars by using existing standard test methods for cement and coal …

Space/Time/Frequency Methods In Adaptive Radar, Christopher D. Peckham

Dissertations

Radar systems may be processed with various space, time and frequency techniques. Advanced radar systems are required to detect targets in the presence of jamming and clutter. This work studies the application of two types of radar systems.

It is well known that targets moving along-track within a Synthetic Aperture Radar field of view are imaged as defocused objects. The SAR stripmap mode is tuned to stationary ground targets and the mismatch between the SAR processing parameters and the target motion parameters causes the energy to spill over to adjacent image pixels, thus hindering target feature extraction and reducing the …

Polymer Pyrolysis And Oxidation Studies In A Continuous Feed And Flow Reactor : Cellulose, Polystyrene, And Polyethylene, Byung-Ik Park

Dissertations

A dual zone, continuous feed tubular reactor is developed to assessthe potential for formation of products from incomplete combustion in thermal oxidation of common polymers. Solid polymer powder (cellulose,polystyrene, or polyethylene) is fed continuously into a volatilization oven where it fragments and vaporizes under continuous steady state conditions. The gas phase polymer fragments flow directly into a second, main flow reactor oven and undergo further pyrolysis and oxidation reaction. Temperatures in the main flow reactor are varied independently of the volatilization zone to observe conditions needed to convert the initial polymer fragmentsto CO₂ and H₂O. Combustion products …

Multi-User Detection For Multi-Rate Ds/Cdma Systems, Jinwen Ma

Dissertations

Wireless cellular communication is witnessing a rapid growth in market, technology and range of services. Current and future demands for wireless communication services motivate the need for handling multi-media traffic types. In a multimedia communication system, users with different and even time-varying rates and quality of services (QoS) requirements, such as voice, image and data, must be accommodated. The use of Spread Spectrum modulation with Code Division Multiple Access (CDMA) technology is an attractive approach for economical spectrally efficient and high quality cellular and personal communication services. This dissertation explores the technologies of applying different interference cancellation techniques to multi-rate …

Hytexpros : A Hypermedia Information Retrieval System, Hong Shen

Dissertations

The Hypermedia information retrieval system makes use of the specific capabilities of hypermedia systems with information retrieval operations and provides new kind of information management tools. It combines both hypermedia and information retrieval to offer end-users the possibility of navigating, browsing and searching a large collection of documents to satisfy an information need. TEXPROS is an intelligent document processing and retrieval system that supports storing, extracting, classifying, categorizing, retrieval and browsing enterprise information. TEXPROS is a perfect application to apply hypermedia information retrieval techniques. In this dissertation, we extend TEXPROS to a hypermedia information retrieval system called HyTEXPROS with hypertext …

In-Line Measurement Of Solibility Of Physical Blowing Agents In Thermoplastic Melts As Related To Extrusion Foaming, Qiang Zhang

Dissertations

A novel in-line method for measuring physical blowing agent solubility in thermoplastic melts in extrusion foaming equipment has been developed in this study. This method uses video microscopy in connection with a foaming extruder (single or twin-screw) to generate solubility data by observing the onset of gas bubble formation/dissolution. This method offers a number of advantages over the existing conventional methods. It can be easily used to obtain solubility data for many foamable thermoplastic-physical blowing agent systems at high pressure and temperature near actual foaming conditions. Data generated using this method could be directly used to characterize and control a …

Finite Fraction Method For Tracking Desinfection By-Product Precursors In Water Treatment, Doanh Van

Dissertations

Dissolved Organic Matter (DOM) has been the subject of recent regulatory activities and agenda. Among them are the Infonnation Collection Rule (ICR), the Disinfectants/Disinfection By-Product Rule (D/DBPR) and the Interim Enhanced Surface Water Treatment Rule (ESWTR). Both the latter two have provisions to limit the formation of disinfection by-products (DBP) by controlling reactivity and removal of DOM or both. Brief regulatory review of these rules was given.

Although the topic of DBP formation potential and DBP precursor removal have been studied by many researchers since Rooks (1974), the efficacy of methods that have been developed to date has been handicapped …

Integrated Product And Process Development Methodologies For Environmentally Conscious Electronic Products, Pingtao Yan

Dissertations

This research focuses on integrated product and process development (IPPD) methodologies for environmentally conscious electronic products. After a review of current research issues in the field of product and process development, a generic framework for IPPD is proposed which describes most of the concerned issues formally as constrained optimization problems. These problems may include such optimization objectives as cost, benefit, and environmental impact. Based on this framework, an IPPD methodology is proposed as a systems approach to competitive and environmentally conscious product and process development. A case study on personal computer development is performed illustrating how to apply the methodology …

Experimental Studies And Modeling Of Mechanical Properties And Morphologies Of In Situ Polymer Composites, Zhigang Li

Dissertations

In this study, a series of experiments was set up in order to analyze the morphology development and mechanical properties of poly(ethylene terephthalate) (PET)/ liquid crystalline polymer (LCP) blends. Simulations of the injection molded blends at various process conditions were performed using CMOLD. In order to determine the effect of the processing parameters on the deformation of the LCP domains during the injection molding, a new analytical method to analyze the melt flow in the advancing melt front (AMF) region was developed. By combining the simulations of the injection molding and analysis of the melt flow in the AMF region, …

Data Hiding In Multimedia - Theory And Applications, Mahalingam Ramkumar

Dissertations

Multimedia data hiding or steganography is a means of communication using subliminal channels. The resource for the subliminal communication scheme is the distortion of the original content that can be tolerated. This thesis addresses two main issues of steganographic communication schemes:

1. How does one maximize the distortion introduced without affecting fidelity of the content?

2. How does one efficiently utilize the resource (the distortion introduced) for communicating as many bits of information as possible? In other words, what is a good signaling strategy for the subliminal communication scheme?

Close to optimal solutions for both issues are analyzed. Many techniques …

Experimental And Phenomenological Study Of Persistent Photoconductivity In Yba2cu3o6 Thin Films, Daniel-Dennis Mcalevy Bubb

Dissertations

Persistent Photoconductivity in YBa₂Cu₃O_6+x thin films is studied by means of infrared photoconductivity measurements after the films have been illuminated with visible light at low temperature. Experimentally, the effect is characterized by the samples' electrical response to infrared light, either causing the resistance to decrease or increase.

A cellular automata model is proposed in explanation of these results and is shown to be consistent with current experimental understanding of this unusual effect, both our results and those of others. The cellular automata model may have application to other unusual optical phenomena exhibited by YBa_{2 …}

The Church As A Social Support For Women: Perspectives Of Female Members Of Selected Seventh-Day Adventist Churches, Norma Greenidge

Dissertations

Problem. The subject of social support and its role in health and well-being ofindividuals has become an important topic to many researchers. This study was designed to discover to what extent female members of Seventh-day Adventist churches perceive their church as providing them with social support.

Method. The instrument used was the Social Provision Scale which measures six aspects of social support--attachment, guidance, nurture, reliable alliance, social integration, and worth. Scores from the 99 White and 48 African American women were compared for each of the six aspects on the basis of ethnicity, age, and marital status using Analysis …

Institutional Activities In International Higher Education : An Assessment Of Advancement Strategies Used At Selected Small Church-Related Colleges And Universities, Janeric Arne Gustavsson

Dissertations

Problem. Small church-related colleges and universities are experiencing financial difficulties. This study assesses the institutional advancement programs at selected Seventh-day Adventist colleges and universities. The purpose of this examination was to analyze "what is" to determine the present-day process of the advancement function, and what "ought to be." These data will also suggest potential areas for growth and development.

Method . The study uses a non-experimental, descriptive design. To accomplish the purpose of the study, the literature on institutional advancement was reviewed to find a useable framework. The instrument used for this study was the one used in Willmer's …

An Assessment Of Home And Classroom Literacy Environments And The Emergent Literacy Development Of Kindergarten Students In Two Southwestern Michigan School Districts, Magdalene Tobias

Dissertations

Problem. In some school districts, low literacy proficiency is a problem of tremendous proportion. Assessing whether a solid foundation is being laid is more important than focusing our efforts at remediation in the later years. This study aimed at investigating the illiteracy problem at the "root" level. The purpose of the study was to determine the characteristics of the home and classroom literacy environments and the development of print, writing, and story concepts of kindergartners in two selected school districts. It also explored whether there was a difference in the performance of students from morning, afternoon, alternate whole-day, and …

Tell Hesban And Vicinity In The Iron Age, Paul J. Ray

Dissertations

Problem. Tell Hesban is a major archaeological ruin in central Transjordan. It was excavated from 1968-76 by Andrews University. However, almost 25 years after the termination of this endeavor, a final report dealing with the Iron Age remains has not yet appeared. Although relatively little remains from the Iron Age, which is the earliest period represented on the tell, an understanding of what is left is nevertheless important for comprehending the role the site played in the region at this time.

Method. A historical research design has been used in this study. The excavated architectural and soil/debris layers were analyzed …

The Relationships Between Student Diligence, Student Support Systems, Other Related Variables And Student Academic Outcomes In High Schools In Grenada, Christon Arthur

Dissertations

Problem. The Ministry of Education on the Caribbean Island of Grenada has been seeking to find ways to improve students' academic performance. The Ministry's emphasis has been on finding ways to make students more responsible for their education and at the same time trying to examine the level of educator support and parental support students receive. This emphasis on the level of educator and parental support that students receive was due in part to the findings of Hinds et al. (1999) that students in the Eastern Caribbean rate the support from parents and educators as being very important to …

An Insider's Perspective: The Dropout Challenge For Canada's First Nations, Patricia Ann Makokis Edd

Dissertations

This modified case study honors the voices of 21 Cree participants, including nine students, six parents, four community leaders and two Elders. This study, written from an insider's perspective, identified more than 50 reasons why First Nations students dropped out of three provincial high schools located in northern Alberta, Canada. The results were collapsed into several categories that can best be generalized as resulting from the effects of colonization. Canada's First Nations have a long history of oppression, colonization, and the resultant soul wounds. The four participant groups collectively identified five common themes why students dropped out of provincial high …

The Current Structure Of Intellect Remediation Lab As An Intervention For Deficient Readers In Grades 3, 4, And 5, Donna Turner Campbell

Dissertations

Problem. Educational testing procedures focus on identification and classification of students rather than on remediation for their abilities. The Structure of Intellect (SOI) model proposes a multidimensional view of intelligence with a focus on remediation for underdeveloped or nonexistent abilities as they relate to school achievement.

Purpose. The purposes of this study were to determine if participation in the SOI remediation lab had a measurable effect on reading achievement with third-, fourth-, and fifth-grade students, and to describe SOI learning profiles of students with below grade reading skills.

Methodology. The subjects for this quasi-experimental study were third-, fourth-, and …

Leadership Requirements In The 21st Century : The Perceptions Of Canadian Public Sector Leaders, M. Ruth Dantzer

Dissertations

Problem. Since 1995, with the realization that by 2005 more than 61% of executives in the senior ranks of the Canadian Public Service would be eligible for retirement (La Releve, 1998), the need to recruit and develop competent leaders has become a matter of urgent attention.

Method. Public sector leaders were surveyed by mail-in questionnaires as to their ratings of a set of leadership competencies. Analogue research for privatesector leaders, conducted by a colleague, was incorporated for some analysis. A stratified sample of the general public was also surveyed by telephone regarding a subset of the same competencies.

Results. Public …

On The Edge Of The Envelope. A Case Study Of The Children's Initiative: An Inquiry Into Collaboration And Shared Vision, Laurie Coskey Edd

Dissertations

While there are many collaborative efforts throughout the country, few have the breadth or the scope of the San Diego Children's Initiative. The general purpose of this research study was to analyze and develop an interpretive case study describing the initial collaborative process of the Strategic Action Committee of the San Diego Children's Initiative. The study focused on the initial phase of the collaboration which took place from November of 1993 through April of 1995. This study sought to determine some factors that may influence the potential success of a large-scale, multi-sector, private-public collaborative effort. The research analyzed the success …

A Cross-Case Study Of Teacher Perceptions Of Program Design And Teaching Efficacy: The Seaview Reading Support Program, Susan L. Bowers Smith Edd

Dissertations

Teachers at Seaview Elementary School developed an innovative reading support program delivered by classroom teachers to increase the achievement of children who struggled to read literature in the district's core curriculum. Although studies of the program's impact on student achievement indicated that many of the children who received services in the classroom were able to fluently read grade level materials and improve their scores on standardized tests, issues created by the additional burden of this instruction on some teachers prevented the integration of the program into other grade levels and schools in the Seaview School District and Seaview Elementary School. …

From Warriors To Wingtips: The Leadership Transition Of Retired Officers Into The Public Sector, Lynn M. Eldred Edd

Dissertations

For personal and financial reasons some retired military officers seek second careers in the public sector. In entering local government, they are leaving a unique organization, and encountering a very different organizational culture. This study used grounded theory methodology to identify the key military leadership strategies and behaviors learned by military officers and to examine their applicability to local government. It focused on eleven retired naval and marine officers who served twenty or more years, attained a rank of lieutenant commander or major and above, and had worked in local San Diego government at the mid-management or executive level less …

An Historical Case Study: The Pregnant Minor Program At Garfield High School, 1975–1999, William E. Law Edd

Dissertations

The researcher conducted an historical case study of the Garfield High School Pregnant Minor Program (1975–1999) which is one of three pregnant minor programs in the San Diego Unified School District. The primary purpose of this study was to provide data about the history and background of this program which may be significant to the decision makers who develop policies regarding pregnant minor programs in the district. The second purpose of the study was to provide data which may be helpful to community members, educators, policy makers, and student-parents about the issues and problems faced by students-parents which would, hopefully, …

Career And Family: A Qualitative Study Of Working Mothers, Barbara Crummer Lincoln Edd

Dissertations

The purpose of this dissertation was to explore the lives of working mothers. The dramatic increase of mothers in the workforce in the past 40 years has led to an increasingly common lifestyle: women filling the roles of mother and professional concurrently. This dissertation used the personal narrative qualitative methodology to examine the lives of working mothers. Ten female graduates of the University of San Diego's Law School (JD), Business School (MBA) and Educational Administration Programs were interviewed by the researcher. These women have been in the workplace for an extended period of time, are currently raising at least one …

A Comparative Study Of Leadership Characteristics Of Principals In Charter Schools And Traditional Schools, Roger M. Mestinsek Edd

Dissertations

The purpose of this study was to examine the similarities and differences in preferred leadership qualities among a random sample of principals of traditional elementary schools in California, traditional elementary schools in Alberta, Canada, and selected charter schools in the United States. The intent of the research was to identify the preferred leadership practices of each study group to determine and report significant differences and similarities. Seventy-five principals were randomly selected, 25 from each of the three study groups, to complete the survey. Forty-two principals (56%) returned surveys. Of the surveys returned, 40 were usable for the study. The theoretical …