The frequency spectrum allocated to cellular mobile telephone systems is very limited. Efficient channel assignment schemes can significantly increase the utilization of the available frequency channels. Virtually Fixed Channel Assignment (VFCA) is a dynamic channel assignment method. The idea behind it is simple: each cell is allocated a set of nominal channels. A call request generated in a cell is assigned a nominal channel if one is available. Otherwise, a channel from an adjacent cell is borrowed to serve this call as long as frequency interference constraints are satisfied. VFCA is a promising method because (i) it is efficient in channel assignment, and (ii) it is relatively easy to implement compared to other dynamic channel assignment methods. VFCA has been analyzed based primarily on simulation studies in the past twenty years. In this thesis, we focus our study on development of new channel borrowing strategies and analytical models for VFCA. The contribution of this work is summarized as follows. (1) Development of an queuing model for performance analysis of VFCA. This model may also be used to conduct sensitivity analysis on some system parameters when VFCA is used. (2) Proposed a new channel reservation scheme for handoffs. (In a cellular system, when a call using a channel crosses a cell boundary, it needs to be handed off to a new channel in the new cell. This is called a handoff.) An optimization model for this channel reservation scheme is developed. (3) Applied the fluid-flow approach to modeling an integrated mobile cellular system that uses VFCA to estimate the distribution of data queue length in a cell of the system. These results are useful in the design, performance analysis and optimization of VFCA schemes.

A global schema is an integrated view of heterogeneous databases used to support data sharing among independent, existing databases. Global schema design complexities arise from the volume of details, design choices, potential conflicts, and interdependencies among design choices. The methodology described provides a framework for efficient management of these critical dimensions in generating and evaluating alternative designs. The methodology contains three major steps. First, differences due to the varying local data models are resolved by converting each local schema to an equivalent schema in a unifying data model. Second, the entity types of the local schemas in the unifying model are grouped into clusters called common areas. All the entity types in a common area can possibly be merged via generalization. For each common area, semantic information is defined that drives the merging process. Third, each common area is integrated into the global schema by applying a set of generalization operators. Mapping rules are then defined to resolve differences in the representations of equivalent attributes. Th integration of the local schemas is based on equivalence assertions. Four types of attribute equivalences are defined: two attributes may be locally or globally equivalent, and they can be key or non-key. Strategies for handling each of these cases are proposed and evaluated. The global schema design methodology includes several algorithms which may assist a designer. One algorithm analyzes a set of equivalence assertions for consistency and completeness including resolution of transitively implied assertions. A second algorithm performs an interactive merge of a common area by presenting the possible generalization actions to the designer. It supports the theme that many generalization structures can be possible, and the appropriate structure often depends on designer preferences and application requirements. The methodology is evaluated for several cases involving real databases. The cases demonstrate the utility of the methodology in managing the details, considering many alternatives, and resolving conflicts. In addition, these cases demonstrate the need for a set of computer-aided tools; for even a relatively small case, the number of details and design choices can overwhelm a designer.

No description available.

A high speed, 125 mega-bit per second data rate, data communication channel using fiber optic technology is described. Medical image data, generated by CT scanner or magnetic resonance imaging type imaging equipment, passes from standard American College of Radiology - National Electrical Manufactures Association (ACR-NEMA) interface equipment to the High Speed Fiber Optic Network Interface (HSFONI). The HSFONI implements the ACR-NEMA standard interface physical layer with fiber optics. The HSFONI accepts data from up to 8 devices and passes data to other devices or to a data base archive system for storage and future viewing and analysis. The fiber components, system level, and functional level considerations, and hardware circuit implementation are discussed.

This thesis seeks to understand the past and present state of engineering education and to plot a course for its future evolution. This research is limited to engineering education as it has taken place in North American universities during the last half of the 20th century. Within this context, broad trends are described. The description is supplemented with a case study of a unique and innovative engineering programme. The trends and case study form the foundation of a synthesis, and alternative vision, for higher education and engineering education. The intended audience of this thesis includes those who teach, design curriculum, or administer engineering education programmes. The description of the current state of engineering education contains analyses of the state and of the gaps within it. Both of these analyses are based almost exclusively on publicly available documentation. The present state of engineering is drawn from accreditation criteria. Critiques of the current state and suggestions for future change are drawn from reports commissioned by groups affiliated with professional engineering. The discussions identify recurring themes and patterns. Unlike the analysis of the literature, the case study merges interview evidence and personal experience with the available documentation. The synthesis and visions continue the trend away from formal sources towards experiences and beliefs. Engineering education research is in its infancy and shows few signs of maturing. There is no documented, common framing of engineering education nor have there been any efforts in this regard. Few sources address broad issues and those that do lack theoretical rigour. The visions for engineering education are simple amalgams of visions for the profession and for general higher education. The Department of Systems Design Engineering has enjoyed great past successes because of its unique vision that combines the theories of systems, complexity, and design with the discipline of engineering. Its recent decay can be traced to its faculty having collectively lost this vision. The original vision for Systems Design Engineering holds promise as a means to reinvent and reinvigorate both the engineering profession and engineering education. For this renaissance to be successful a theoretically rigorous research programme assessing the past, present, and future of engineering and engineering education must be developed.

Haptic applications often employ devices with many degrees of freedom in order to allow the user to have natural movement during human-machine interaction. From the development point of view, the complexity in mechanical dynamics imposes a lot of challenges in modelling the behaviour of the device. Traditional system identification methods for nonlinear systems are often computationally expensive. Moreover, current research on using neural network approaches disconnect the physical device dynamics with the identification process. This thesis proposes a different approach to system identification of complex haptic devices when analytical models are formulated. It organizes the unknowns to be identified based on the governing dynamic equations of the device and reduces the cost of computation. All the experimental work is done with the Freedom 6S, a haptic device with input and feedback in positions and velocities for all 6 degrees of freedom . <br /><br /> Once a symbolic model is developed, a subset of the overall dynamic equations describing selected joint(s) of the haptic robot can be obtained. The advantage of being able to describe the selected joint(s) is that when other non-selected joints are physically fixed or locked up, it mathematically simplifies the subset dynamic equation. Hence, a reduced set of unknowns (e. g. mass, centroid location, inertia, friction, etc) resulting from the simplified subset equation describes the dynamic of the selected joint(s) at a given mechanical orientation of the robot. By studying the subset equations describing the joints, a locking sequence of joints can be determined to minimize the number of unknowns to be determined at a time. All the unknowns of the system can be systematically determined by locking selected joint(s) of the device following this locking sequence. Two system identification methods are proposed: Method of Isolated Joint and Method of Coupling Joints. Simulation results confirm that the latter approach is able to successfully identify the system unknowns of Freedom 6S. Both open-loop experimental tests and close-loop verification comparison between the measured and simulated results are presented. <br /><br /> Once the haptic device is modelled, fuzzy logic is used to address chattering phenomenon common to strong virtual effects. In this work, a virtual wall is used to demonstrate this approach. The fuzzy controller design is discussed and experimental comparison between the performance of using a proportional-derivative gain controller and the designed fuzzy controller is presented. The fuzzy controller is able to outperform the traditional controller, eliminating the need for hardware upgrades for improved haptic performance. Summary of results and conclusions are included along with suggested future work to be done.

Call number: LD2668 .T4 1986 P68 / Master of Science / Computing and Information Sciences

This study is a quantitative, quasi-experimental inquiry into the effectiveness of motivational instructional strategies on undergraduate math students' subject learning. Secondarily, it examines the effects of the motivational strategies on the effort students exert in lesson activities, and on their motivation within the lesson. The treatment in this study is based on the MUSIC® Model of Academic Motivation and was conducted within a single lesson. The existing literature shows that motivational instructional design by lay educators is often hindered by the complexity of the field, and by the specialization of existing motivational models. The MUSIC Model holds some promise in organizing and simplifying motivational strategies such that classroom educators and non-instructional specialists can apply them in their lesson design. The research questions for the study are "How do MUSIC based motivational instructional strategies affect student learning, student effort and the five components of students' motivation within an undergraduate math lesson?" Two sections of a single mathematics course, taught by one instructor, were participants in the study. The treatment section received the MUSIC intervention for the lesson. This research intervention was created by mapping each of the lesson activities to each component in the motivational model, thereby generating motivation enhanced adaptations of lesson activities. Students were tested and surveyed post-lesson for all three variables; subject learning, effort and lesson motivation perceptions. Results of the study inform and facilitate the design and implementation of further engaged lessons based on the MUSIC Model. / A Dissertation submitted to the Department of Educational Psychology and Learning Systems in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester 2018. / November 8, 2018. / Higher Education, Learning and Motivation, Mathematics Teaching, Motivation and engagement, MUSIC Model of Academic Motivation, STEM Teaching / Includes bibliographical references. / Vanessa Dennen, Professor Directing Dissertation; Stephen McDowell, University Representative; James Klein, Committee Member; Insu Paek, Committee Member.

In order for microfluidics devices to be marketable, they must be inexpensive and easy to use. Two projects were pursued in this study for this purpose. The first was the design of a chip alignment system for visual feedback, in which a two-layer microfluidic chip was placed under a camera and an image processing and linear algebra program aligned a computer model to it. The system then translated the new locations of air valves and could detect valve activation in a chip filled with food coloring. The second was the design of a cheap, portable system to detect phosphorus in water. This system could not be completed due to time constraints, but the methods were detailed, and design ideas were laid out for future work. / by Ian Gerstel. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Makerspaces are fertile grounds for students to develop innovative products infused with STEAM principles and cross disciplinary content knowledge; build technological fluency; and support positive developmental growth. Yet, rarely do Makerspaces prioritize these outcomes. Rather, they tend to revolve around the creation of novel objects using cutting-edge technology; craftwork unhinged from their historical, social, political, or academically-relevant underpinnings; and/or the hacking of so-called “black boxes”. What happens when an educator designs and implements a research-based and content-driven in-school Makerspace? Drawing on field observations, interviews, artifact analysis, and the Developmental Assets Profile (DAP) survey, this mixed methods study explored the experiences of students from two urban middle school classes (n=51) who participated in a social action themed Makerspace called the “Tech Café.” Working from a transformative research perspective, the Tech Café also sought to address the “participation divide”— a term suggesting that higher socioeconomic status students have more opportunity to produce media creatively than students of low socioeconomic status. Qualitative results indicated that students reported increased agency in their ability to effect positive change in their world. They engaged in powerful collaborations with diverse members of the school’s learning community as they worked toward solutions using low- and high-technology tools. Their products included a cigarette smoke detecting shirt, an edible insect bug stand, and a stationary making kit utilizing recycled paper. Student profiles incorporated their chosen social issue; steps and challenges in product creation; and outcomes pertaining to technological fluency and sense of agency to affect change. Findings showed that students may have benefited from scaffolding to deepen their understanding of important social issues through research. Quantitative results of the DAP were statistically analyzed according to measures of Positive Identity, Positive Values, Commitment to Learning, Empowerment, and Social Competencies and indicated that no statistically significant differences existed in the pretest-posttest survey scores of participants (n=30). However, a descriptive analysis of score improvement showed that students who successfully created products in the Tech Café moved to higher DAP score ranges more often than those who did not create products. The study concludes with recommendations pertaining to the implementation of Makerspaces in schools.