Digital Commons Network^™

Providing Guaranteed Qos In The Hose-Modeled Vpn, Dong Wei

Dissertations

With the development of the Internet, Internet service providers (ISPs) are required to offer revenue-generating and value-added services instead of only providing bandwidth and access services. Virtual Private Network (VPN) is one of the most important value-added services for ISPs.

The "classical" VPN service is provided by implementing layer 2 technologies, either Frame Relay (FR) or Asynchronous Transfer Mode (ATM). With FR or ATM, virtual circuits are created before data delivery. Since the bandwidth and buffers are reserved, the QoS requirements can be naturally guaranteed. In the past few years, layer 3 VPN technologies are widely deployed due to the …

An Approximate Search Engine For Structure, Huiyuan Shan

Dissertations

As the size of structural databases grows, the need for efficiently searching these databases arises. Thanks to previous and ongoing research, searching by attribute-value and by text has become commonplace in these databases. However, searching by topological or physical structure, especially for large databases and especially for approximate matches, is still an art.

In this dissertation, efficient search techniques are presented for retrieving trees from a database that are similar to a given query tree. Rooted ordered labeled trees, rooted unordered labeled trees and free trees are considered. Ordered labeled trees are trees in which each node has a label …

Phase Noise Effects On Ofdm : Analysis And Mitigation, Songping Wu

Dissertations

Orthogonal frequency division multiplexing (OFDM) is a promising technique which has high spectrum efficiency and the robustness against channel frequency selectivity. One drawback of OFDM is its sensitivity to phase noise. It has been shown that even small phase noise leads to significant performance loss of OFDM. Therefore, phase noise effects on OFDM systems need to be analyzed and methods be provided to its mitigation.

Motivated by what have been proposed in the literature, the exact signal to interference plus noise ratio (SINR) is derived in this dissertation for arbitrary phase noise levels. In a multiple access environment with multiple …

Enhancing Qos Provisioning And Granularity In Next Generation Internet, Jie Yang

Dissertations

Next Generation IP technology has the potential to prevail, both in the access and in the core networks, as we are moving towards a multi-service, multimedia and high-speed networking environment. Many new applications, including the multimedia applications, have been developed and deployed, and demand Quality of Service (QoS) support from the Internet, in addition to the current best effort service. Therefore, QoS provisioning techniques in the Internet to guarantee some specific QoS parameters are more a requirement than a desire. Due to the large amount of data flows and bandwidth demand, as well as the various QoS requirements, scalability and …

Statistical Anomaly Denial Of Service And Reconnaissance Intrusion Detection, Zheng Zhang

Dissertations

This dissertation presents the architecture, methods and results of the Hierarchical Intrusion Detection Engine (HIDE) and the Reconnaissance Intrusion Detection System (RIDS); the former is denial-of-service (DoS) attack detector while the latter is a scan and probe (P&S) reconnaissance detector; both are statistical anomaly systems.

The HIDE is a packet-oriented, observation-window using, hierarchical, multi-tier, anomaly based network intrusion detection system, which monitors several network traffic parameters simultaneously, constructs a 64-bin probability density function (PDF) for each, statistically compares it to a reference PDF of normal behavior using a similarity metric, then combines the results into an anomaly status vector that …

Mobile Agent Based Distributed Network Management : Modeling, Methodologies And Applications, Jian Ye

Dissertations

The explosive growth of the Internet and the continued dramatic increase for all wireless services are fueling the demand for increased capacity, data rates, support of multimedia services, and support for different Quality of Services (QoS) requirements for different classes of services. Furthermore future communication networks will be strongly characterized by heterogeneity. In order to meet the objectives of instant adaptability to the users' requirements and of interoperability and seamless operation within the heterogeneous networking environments, flexibility in terms of network and resource management will be a key design issue. The new emerging technology of mobile agent (MA) has arisen …

Ad Hoc Network Security And Modeling With Stochastic Petri Nets, Congzhe Zhang

Dissertations

Advances in wireless technology and portable computing along with demands for high user mobility have provided a major promotion toward the development of ad hoc networks. These networks feature dynamic topology, self-organization, limited bandwidth and battery power of a node. Unlike the existing commercial wireless systems and fixed infrastructure networks, they do not rely on specialized routers for path discovery and traffic routing. Security is an important issue in such networks. Typically, mobile nodes are significantly more susceptible to physical attacks than their wired counterparts.

This research intends to investigate the ad hoc network routing security by proposing a performance …

Uncertainty Analysis In Ecological Risk Assessment Modeling, Tepwitoon Thongsri

Dissertations

A probabilistic approach employing Monte Carlo simulations for assessing parameter and risks as probabilistic distributions was used in an ecological risk assessment (ERA) model to characterize risk and address uncertainty. This study addresses the following sources of uncertainty: parameter inputs in the ERA models, risk algorithms and uncertain input concentrations. To achieve this objective, both sensitivity and uncertainty analyses are being conducted. Monte Carlo simulations were used for generating probabilistic distributions of parameter and model uncertainty. All sensitivity, uncertainty, and variability analyses were coded in Visual Basic as part of the ERA model software version 2001, which was developed under …

Qos Provisioning In Multimedia Streaming, Hong Zhao

Dissertations

Multimedia consists of voice, video, and data. Sample applications include video conferencing, video on demand, distance learning, distributed games, and movies on demand. Providing Quality of Service (QoS) for multimedia streaming has been a difficult and challenging problem. When multimedia traffic is transported over a network, video traffic, though usually compressed/encoded for bandwidth reduction, still consumes most of the bandwidth. In addition, compressed video streams typically exhibit highly variable bit rates as well as long range dependence properties, thus exacerbating the challenge in meeting the stringent QoS requirements of multimedia streaming with high network utilization. Dynamic bandwidth allocation in which …

Ultra-Wideband Technology For Short-Range Wireless Communication, Li Zhao

Dissertations

The ultra-wideband (UWB) radio core idea is to open large amounts of spectrum to a variety of users with little mutual interference between them. While ultra-wideband is being championed by several commercial companies, this technology has not followed the conventional path where commercial interest is preceded by years of academic research. This work attempts to fill in some of the gap by studying fundamental properties of communications with impulse-based radio UWB signals. We study jam resistance and capacity of UWB. Jam resistance is analyzed for binary pulse position modulation (PPM) with the interference being modeled as correlated Gaussian. Closed-form expressions …

Transmission And Detection For Space-Time Block Coding And V-Blast Systems, Lei He

Dissertations

This dissertation focuses on topics of data transmission and detection of space -time block codes (STBC). The STBCs can be divided into two main categories, namely, the orthogonal space-time block codes (OSTBC) and the quasi-orthogonal space-time codes (Q-OSTBC). The space-time block coded systems from transceiver design perspective for both narrow-band and frequency selective wireless environment are studied. The dissertation also processes and studies a fast iterative detection scheme for a high-rate space-time transmission system, the V-BLAST system.

In Chapter 2, a new OSTBC scheme with full-rate and full-diversity, which can be used on QPSK transceiver systems with four transmit antennas …

Mixing Enhancement By Dual Speed Rotating Stirrer, Arnaud Goullet

Dissertations

Stirring is a well-known means of fluid mixing due to the emergence of complex patterns in the flow, even at low Reynolds numbers. In this work, we consider a stirrer rotating along a circular trajectory at constant speed. The fluid flow, considered incompressible, inviscid and two dimensional (in a circular container), is modeled by a point vortex model consisting of a vortex rotating in a circular container at constant angular speed. The mixing problem is addressed by considering the Hamiltonian form of the advection equations formulated in a frame of reference moving with the vortex. The dynamics of passive fluid …

Hybrid Routing And Bridging Strategies For Large Scale Mobile Ad Hoc Networks, Sheng Xu

Dissertations

Multi-hop packet radio networks (or mobile ad-hoc networks) are an ideal technology to establish "instant" communication infrastructure for military and civilian applications in which both hosts and routers are mobile. In this dissertation, a position-based/link-state hybrid, proactive routing protocol (Position-guided Sliding-window Routing - PSR) that provides for a flat, mobile ad-hoc routing architecture is described, analyzed and evaluated. PSR is based on the superposition of link-state and position-based routing, and it employs a simplified way of localizing routing overhead, without having to resort to complex, multiple-tier routing organization schemes. A set of geographic routing zones is defined for each node, …

Enriching And Designing Metaschemas For The Umls Semantic Network, Li Zhang

Dissertations

The disparate terminologies used by various biomedical applications or professionals make the communication between them more difficult. The Unified Medical Language System (UMLS) of the National Library of Medicine (NLM) is an attempt to integrate different medical terminologies into a unified representation framework to improve decision making and the quality of patient care as well as research in the health-care field. Metathesaurus (META) and Semantic Network (SN) are two main components of the UMLS system, where the SN provides a high-level abstract of the concepts in the META.

This dissertation addresses three problems of the SN. First, the SN's two-tree …

Novel Internally-Staged Ultrafiltration For Protein Purification, Meredith Ann Feins

Dissertations

A new ultrafiltration technique based on a multimembrane stack has been developed to fractionate proteins closer in molecular weight than conventionally possible. The technique is illustrated here by obtaining a pure protein product from a binary protein mixture. By employing membranes in series using the same membrane without any gaskets or spacers in-between, ultrafiltration is carried out to separate two proteins relatively close in molecular weight. Flat membranes, of the same molecular weight cutoff (MWCO) 30,000 or 100,000, are stacked together in the desired number, and ultrafiltration takes place. The membrane rejection of a protein is amplified with each additional …

Nonlinear Long-Wave Interfacial Stability Of Two-Layer Gas-Liquid Flow, Tetyana Segin

Dissertations

The flow of two immiscible viscous fluids in a thin inclined channel is considered, in either a cocurrent or countercurrent regime. Following the air-water case, which is found in a variety of engineering systems, we allow the upper fluid to be either compressible or incompressible. The disparity of the length scales and the density and viscosity ratios of the two fluids is exploited through a lubrication approximation of the conservation of mass and the Navier-Stokes equations. As a result of this long-wave theory, a coupled nonlinear system of partial differential equations is obtained that describes the evolution of the interfacial …

Cleaner Technologies As An Aspect Of Sustainable Tourism: Carribbean Case Studies, Fitzgerald J. Yaw Jr.

Dissertations

Tourists are becoming increasingly sophisticated in their selection of tourism destination. A major factor that has been gaining importance in their choice set is the environmental quality of their preferred destination. Tourism planners need to recognize that the sustainability of their destination and its various offerings necessitates the consideration of environmental protection and conservation-related issues. This dissertation undertakes the case study methodology to explore the link between implementing cleaner technologies, a major environmental issue, and sustainable tourism.

The Caribbean is a region in the world that is strongly dependent on tourism for its economic development. Thus the analysis of how …

Functioning Among Taiwanese Families With A Child Having Duchenne Muscular Dystrophy, Jih-Yuan Chen Phd, Msn, Rn

Dissertations

A cross-sectional study was designed to determine the factors with functioning among Taiwanese families with a child having Duchenne Muscular Dystrophy (DMD). This research investigated the level of a child's mobility upon family hardiness, functioning, and support from a family perspective. A total sample of 126 of participants was parents of children with DMD. Parents completed basic demographic information, the Family Assessment Device, Family Hardiness Index, Duke Health Profile, and Family APGAR. Pearson Correlation Coefficient test was performed to examine relationships between independent and dependent variables. To determine if the levels of child's mobility, family characteristics, family hardiness, family health, …

Organizational Structure And The Creative Process, Edward C. Bowen Edd

Dissertations

A creative edge can be a powerful source of competitive advantage in business, in war, in the arts, in science, and in life. In fact, creativity, innovation and the ability to adapt and change organizational structures in response to an increasingly fast-paced and competitive business environment are increasingly seen as essential for the success of many organizations. A current trend in organizational theory associates increases in formalization and both horizontal and vertical integration with decreases in an organization's ability to innovate and adapt. Consequently, organizational change efforts often involve moving from traditional, hierarchical structures toward flatter, more flexible types of …

Implementing Student Learning Outcomes: The Link To Accreditation In California Community Colleges, Lori Waite Edd

Dissertations

As the public demands accountability in higher education, regional accrediting bodies are under pressure from external governmental agencies, as well as from key stakeholders, to demonstrate their effectiveness and more specifically, provide evidence of student learning. All regional accrediting agencies now have incorporated some level of student learning outcomes into their criteria for reaffirmation of accreditation. This case study describes how three California public community colleges are implementing student learning outcomes on their campuses. Administrators, faculty and staff were interviewed about perceptions and insights related to learning outcomes. Artifact analysis was conducted to establish credibility and data triangulation. Findings suggest …

Explicit Writing Instruction: Effects On Sixth Grade Students’ Writing And Reading Achievement, Jennifer Hamby Edd

Dissertations

The purpose of this quantitative study was to examine the effect of explicit writing instruction on sixth grade students' writing growth and achievement as measured by holistic and analytic assessment. This research responds directly to the need for additional research on effective reading and writing instruction (Langer & Allington, 1992; The College Board, 2003). The preponderance of research in writing has been devoted to early writing. Less evidence is available to examine the effect of writing instruction at the sixth grade level. Writing samples from 124 sixth grade students at two elementary schools were used in this study. The two …

Examining The Lived Experiences Of Out Gay And Lesbian K-12 Educators, William Dejean Edd

Dissertations

The purpose of this study was to examine the lived experience of gay and lesbian K-12 educators who consider themselves out within the classrooms in which they teach. With gay and lesbian issues receiving increased visibility within the K-12 setting, researchers have begun to examine the experiences of gay and lesbian K-12 educators (Harbeck, 1992; Letts IV & Sears, 1999; Jennings, 1994; Kissen, 1996; Parker, 2001; Sanlo, 1999) within this context. Yet few research studies have specifically examined gay and lesbian educators who consider themselves out in the classroom in which they teach. Five gay male teachers and five lesbian …

Webquest Design Strategies: A Case Study Measuring The Effect Of The Jigsaw Method On Students’ Personal Agency Beliefs, Engagement, And Learning, James P. Frazee Edd

Dissertations

The WebQuest model continues to grow in popularity, with teachers from around the world and many teacher-educators and experts in the field of educational technology espousing its potential to extend content knowledge and promote higher level thinking. While the model is well received by teachers and students alike, most evidence of its effectiveness is anecdotal, and there is very little in the way of empirical research on the elements that make an effective WebQuest. Furthermore, rich descriptions of how students interact during a well-developed WebQuest are largely absent from the literature. In short, the WebQuest model suffers from a lack …

What Effect Does The Hampton Inn 100% Unconditional Satisfaction Guarantee Have On Customer Loyalty?, Jeffrey Alan Carlstead Edd

Dissertations

Trust has been identified as a key factor in sustaining customer loyalty in service sector industries. The Hampton Inn hotel chain attempts to promote trust and loyalty among its customers by offering a 100% unconditional satisfaction guarantee. The purpose of this study was to investigate the extent to which a specific value-enhancing feature—the 100% unconditional guarantee—is likely to influence customer loyalty. In this study, loyalty was defined in two ways: (a) the likelihood of returning to another Hampton Inn property and (b) the likelihood of returning to the particular Hampton Inn at which this study was conducted. In the study, …

Factors Influencing Middle-Aged And Older Latin American Women's Participation In Physical Activity, Stephanie Vaughn Phd

Dissertations

Ethnographic methodology was used to explore the factors that influence middle-aged and older Latin American women's participation in physical activity. Semi-structured interviews and field observations were used to elicit information from the twenty five Latin American women in this study sample. Perceptions of health, the health activities in which the women engage, and the factors that influenced their participation in physical activity comprised the three categories of responses. Facilitators and barriers were identified as the two primary groups and were further sorted into intrinsic or extrinsic factors. A sense of self, decreased feelings of stress, wellbeing, managing chronic disease, the …

Total Resource Sharing Among Collegiate And Public Libraries In The Commonwealth Of The Northern Mariana Islands: A Narrative Case Study, Jimmie L. Ellis Edd

Dissertations

Especially in difficult economic times, educational and public sector organizations are under pressure to do more with less. At times, this means consolidating organizations to avoid costly duplication. This study focused on three attempts at consolidation that occurred on the island of Saipan and the two major outer islands of the Commonwealth of the Northern Mariana Islands (CNMI). These efforts entailed total resource sharing across the collegiate and public libraries on these islands. Total resource sharing among the collegiate and public libraries in the CNMI was first envisioned in the late 1980s and early 1990s. By 1994, the concept of …

Wresting And Arresting Sense In Academe: The Complicated Discursive Structures Of Female Assistant Professors, Alana M. Nicastro Edd

Dissertations

Women in academe often become entangled in an intricate equation of sensemaking as they work to balance the professional demands of teaching, research, and service, while at the same time learning the political and moral meanings of being a scholar. Structuration theory offers avenues for closely examining communicative strategies women utilize to navigate their roles as assistant professors. Through intensive interviews with seven female assistant professors this research investigates their process of wresting and arresting sense of the complicated roles, rules, and structures in academe. Analysis of interview data reveals the multiple discourses that frame organizational practices that facilitate and …

The Relationship Between Leadership Styles And Labour Disputes In British Columbia's Public Schools, Yanping Wang Edd

Dissertations

For the last decade, adversarial relationships between teachers' associations and district administrators in the British Columbia public school system have been commonplace, frequently resulting in formal grievances and arbitration. Since dealing with these issues imposes enormous costs on both teachers' unions and school boards, this study used hierarchical regression analysis to explain why some schools have fewer grievances filed than other schools in the province. Specifically, this study used data gathered from 160 principals in the British Columbia public school system to examine the extent to which school demographics and principal leadership style helped explain variation in the rate of …

Nobody's Ever Asked Me That Before: Middle School Students Talk About Motivation To Achieve In School Contexts, Erika Daniels Edd

Dissertations

The purpose of this study was to explore whether or not a connection exists between students' school contexts and their academic and social choices by listening to the voices of first year middle school students. The intent of this study was to provide teachers with a way to reconceptualize adolescents as learners. Research suggests that there are two distinct approaches to the study of motivation. Some researchers believe that motivation can be externally enacted through exams, assessments, and other accountability measures. Other researchers believe that motivation is internally generated through the relationships students build, through their beliefs about learning, and …

The Effect Of Force Feedback On Student Reasoning About Gravity, Mass, Force And Motion, Linda Bussell Edd

Dissertations

The purpose of this study was to examine whether force feedback within a computer simulation had an effect on reasoning by fifth grade students about gravity, mass, force, and motion, concepts which can be difficult for learners to grasp. Few studies have been done on cognitive learning and haptic feedback, particularly with young learners, but there is an extensive base of literature on children's conceptions of science and a number of studies focus specifically on children's conceptions of force and motion. This case study used a computer-based paddleball simulation with guided inquiry as the primary stimulus. Within the simulation, the …