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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.
321

Silicon carbide RF-MEM resonators

Dusatko, Tomas A. January 2006 (has links)
A low-temperature (<300°C) method to fabricate electrostatically actuated microelectromechanical (MEM) clamped-clamped beam resonators has been developed. It utilizes an amorphous silicon carbide (SiC) structural layer and a thin polyimide spacer. The resonator beam is constructed by DC sputtering a tri-layer composite of low-stress SiC and aluminum over the thin polyimide sacrificial layer, and is then released using a microwave O 2 plasma etch. Deposition parameters have been optimized to yield low-stress films (<50MPa), in order to minimize the chance of stress-induced buckling or fracture in both the SiC and aluminum. Characterization of the deposited SiC was performed using several different techniques including scanning electron microscopy, EDX and XRD. / Several different clamped-clamped beam resonator designs were successfully fabricated and tested using a custom built vacuum system, with measured frequencies ranging from 5MHz to 25MHz. A novel thermal tuning method is also demonstrated, using integrated heaters directly on the resonant structure to exploit the temperature dependence of the Young's modulus and thermally induced stresses.
322

An investigation into the appropriateness of using agile processes to build an educational management information system

Sammadyar, Abdul Wahid January 2010 (has links)
<p>Since there was a need for an Educational Management Information System (EMIS) in the Ministry of Education in Afghanistan, we designed and implemented a prototype for use in the ministry and investigated the appropriateness of using Agile methods for producing the EMIS. The prototype consisted of a database containing data about schools and a Dari interface which was used by educational planners, managers and policy makers of the ministry for decision making and planning. Agile methods are relatively new in software engineering and have an approach and development guidelines which strive for user satisfaction and early incremental delivery of software. We adapt them to local conditions due to their collaborative client-developer approach. The interface, a key component, is easy to use and e cient. The key research result is an evaluation concerning the appropriateness of using Agile Methods for developing the EMIS. Focus groups and surveys were used to develop the prototype and accomplish the study.</p>
323

A guide to improving the e-commerce user interface design

Singh, Alveen January 2005 (has links)
Thesis (M. Tech.: Information Technology)-Dept. of Information Technology, Durban Institute of Technology, 2005 xiv, 170, [20] leaves / This study examines the efficiency, ease of use and ease of understanding of user interface designs implemented in current e-commerce websites. Four South African based e-commerce websites formed the test cases of this study. Selection of the test cases was based on the results and conclusions of previous surveys conducted by an independent research institution. The outcome of that survey identified the most popular e-commerce websites among South African internet users.
324

Hybrid and resilient WDM mesh optical networks

Huang, Hong 12 1900 (has links)
No description available.
325

Design and fabrication of a MEMS magnetic bistable valve

Creyts, Don Stafford IV 12 1900 (has links)
No description available.
326

INFORMATION THEORETIC CRITERIA FOR IMAGE QUALITY ASSESSMENT BASED ON NATURAL SCENE STATISTICS

Zhang, Di January 2006 (has links)
Measurement of visual quality is crucial for various image and video processing applications. <br /><br /> The goal of objective image quality assessment is to introduce a computational quality metric that can predict image or video quality. Many methods have been proposed in the past decades. Traditionally, measurements convert the spatial data into some other feature domains, such as the Fourier domain, and detect the similarity, such as mean square distance or Minkowsky distance, between the test data and the reference or perfect data, however only limited success has been achieved. None of the complicated metrics show any great advantage over other existing metrics. <br /><br /> The common idea shared among many proposed objective quality metrics is that human visual error sensitivities vary in different spatial and temporal frequency and directional channels. In this thesis, image quality assessment is approached by proposing a novel framework to compute the lost information in each channel not the similarities as used in previous methods. Based on natural scene statistics and several image models, an information theoretic framework is designed to compute the perceptual information contained in images and evaluate image quality in the form of entropy. <br /><br /> The thesis is organized as follows. Chapter I give a general introduction about previous work in this research area and a brief description of the human visual system. In Chapter II statistical models for natural scenes are reviewed. Chapter III proposes the core ideas about the computation of the perceptual information contained in the images. In Chapter IV, information theoretic criteria for image quality assessment are defined. Chapter V presents the simulation results in detail. In the last chapter, future direction and improvements of this research are discussed.
327

A Neurocomputational Model of Smooth Pursuit Control to Interact with the Real World

Sadat Rezai, Seyed Omid 24 January 2014 (has links)
Whether we want to drive a car, play a ball game, or even enjoy watching a flying bird, we need to track moving objects. This is possible via smooth pursuit eye movements (SPEMs), which maintain the image of the moving object on the fovea (i.e., a very small portion of the retina with high visual resolution). At first glance, performing an accurate SPEM by the brain may seem trivial. However, imperfect visual coding, processing and transmission delays, wide variety of object sizes, and background textures make the task challenging. Furthermore, the existence of distractors in the environment makes it even more complicated and it is no wonder why understanding SPEM has been a classic question of human motor control. To understand physiological systems of which SPEM is an example, creation of models has played an influential role. Models make quantitative predictions that can be tested in experiments. Therefore, modelling SPEM is not only valuable to learn neurobiological mechanisms of smooth pursuit or more generally gaze control but also beneficial to give insight into other sensory-motor functions. In this thesis, I present a neurocomputational SPEM model based on Neural Engineering Framework (NEF) to drive an eye-like robot. The model interacts with the real world in real time. It uses naturalistic images as input and by the use of spiking model neurons controls the robot. This work can be the first step towards more thorough validation of abstract SPEM control models. Besides, it is a small step toward neural models that drive robots to accomplish more intricate sensory-motor tasks such as reaching and grasping.
328

Leadership based multi-objective optimization with applications in energy systems.

Bourennani, Farid 01 December 2013 (has links)
Multi-objective optimization metaheuristics (MOMs) are powerful methods for solving complex optimization problems but can require a large number of function evaluations to find optimal solutions. Thus, an efficient multi-objective optimization method should generate accurate and diverse solutions in a timely manner. Improving MOMs convergence speed is an important and challenging research problem which is the scope of this thesis. This thesis conducted the most comprehensive comparative study ever in MOMs. Based on the results, multi-objective (MO) versions of particle swarm optimization (PSO) and differential evolution (DE) algorithms achieved the highest performances; therefore, these two MOMs have been selected as bases for further acceleration in this thesis. To accelerate the selected MOMs, this work focuses on the incorporation of leadership concept to MO variants of DE and PSO algorithms. Two complex case studies of MO design of renewable energy systems are proposed to demonstrate the efficiency of the proposed MOMs. This thesis proposes three new MOMs, namely, leader and speed constraint multi-objective PSO (LSMPSO), opposition-based third evolution step of generalized DE (OGDE3), and multi-objective DE with leadership enhancement (MODEL) which are compared with seven state-of-the-art MOMS using various benchmark problems. LSMPSO was found to be the fastest MOM for the problem undertaken. Further, LSMPSO achieved the highest solutions accuracy for optimal design of a photovoltaic farm in Toronto area. OGDE3 is the first successful application of OBL to a MOM with single population (no-coevolution) using leadership and self-adaptive concepts; the convergence speed of OGDE3 outperformed the other MOMs for the problems solved. MODEL embodies leadership concept into mutation operator of GDE3 algorithm. MODEL achieved the highest accuracy for the 30 studied benchmark problems. Furthermore, MODEL achieved the highest solution accuracy for a MO optimization problem of hydrogen infrastructures design across the province Ontario between 2008 and 2025 considering electricity infrastructure constraints.
329

Instructional design process in a web-based learning management system: design, implementation and evaluation issues

Njenga, James Kariuki January 2005 (has links)
<p>Web technologies have necessitated a transformation culture in higher education<br /> institutions. Many of these institutions are employing web technologies whose<br /> development, for varying reasons, is not supported by research in their field and<br /> domain of use. One such field is instructional design for the web learning.<br /> Although there is a lot of research on the most effective instructional design<br /> strategies, the use of research for web-based learning applications has been<br /> limited. <br /> <br /> This thesis reports on a study aimed at transforming the research on instructional<br /> design into practice by designing an instructional design system and providing an<br /> argument for its implementation. The argument is intended to facilitate the design<br /> and development of an instructional design subsystem of the web, that would in<br /> turn offer effective and efficient ways for creating web-based learning materials<br /> to instructors.<br /> <br /> The study started by examining the various paradigms, theories and practices of<br /> instructional design with the intent of using them to enrich and improve the<br /> practice of instructional design in web learning. It undertook a thorough and<br /> systematic review of the literature on instructional design in order to come up<br /> with an instructional design system. The design approach used successful design<br /> patterns that have been used elsewhere, e.g. in software design, to create common<br /> responses or solutions to recurrent problems and circumstances. Instructional<br /> design patterns were identified in this study as the recurrent problems or processes<br /> instructional designers go through while creating instructional materials, whose<br /> solutions can be reused over and over again.<br /> <br /> This study used an iterative developmental research process of finding and<br /> modelling an instructional design process as the research methodology. This<br /> process follows and builds on existing research on instructional models, theories<br /> and strategies, and ensures that the same methodology can be used to test the<br /> theories in the design, thus improving both the research and the design.</p>
330

Situated Reflexive Change : User-Centred Design in(to) Practice

Eriksson, Elina January 2013 (has links)
Technology used in the Swedish workplace is perceived to be controlling, gener- ally still difficult to use, and with a low degree of usability. Even though the field of Human-Computer Interaction (HCI) has been concerned with researching different ways of developing usable systems for at least half a century, there seem to be problems with the diffusion of the results into practice. One of the possible approaches to developing usable systems is user-centred design, and in this thesis I am concerned with the issue of introducing user-centred design and usability work in public authorities and institutions. I will present work done in two different research projects with a focus on change, where the aim has been to introduce or enhance usability work. Through a lens of social construction- ism and reflexivity I will explore the outcome of the projects and the implica- tions for the introduction of user-centred design in practice. Furthermore, I will explore whether the focus on the introduction of usability work might hinder the formation of a sustainable change in the organizations interested in devel- oping usable systems. The research question then becomes; can we introduce usability work in organizations? The answer to this question is no. Instead, we need to change our perspective from introduction to situated reflexive change: focusing on sensemaking and a situated process of ongoing change, where the stakeholders in the organization themselves must play an active and responsible part. This entails a shift from dualism to duality and a reconsideration of what our usability methods can con- tribute with. Furthermore, I will explore possible approaches to working with situated reflexive change with tools that are familiar in the field of HCI, but with an expanded scope. In particular I will discuss field studies conducted by system developers as a tool for making sense of usability issues, personas as a tool for inducing reflexivity in and on practice, and usability coaching as a sensemaking tool for both organizational stakeholders and researchers in order to understand and reflect upon change. / <p>QC 20130118</p>

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