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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.
81

Adaptive Affective Computing: Countering User Frustration

Aghaei, Behzad 28 February 2013 (has links)
With the rise of mobile computing and an ever-growing variety of ubiquitous sensors, computers are becoming increasingly context-aware. A revolutionary step in this process that has seen much progress will be user-awareness: the ability of a computing device to infer its user's emotions. This research project attempts to study the effectiveness of enabling a computer to adapt its visual interface to counter user frustration. A two-group experiment was designed to engage participants in a goal-oriented task disguised as a simple usability study with a performance incentive. Five frustrating stimuli were triggered throughout a single 15-minute task in the form of complete system unresponsiveness or delay. An algorithm was implemented to attempt to detect sudden rises in user arousal measured via a skin conductance sensor. Following a successful detection, or otherwise a maximum of a 10-second delay, the application resumed responsiveness. In the control condition, participants were exposed to a “please wait” pop-up near the end of the delay whereas those in the adaption condition were exposed to an additional visual transition to a user interface with calming colours and larger touch targets. This proposed adaptive condition was hypothesized to reduce the recovery time associated with the frustration response. The experiment was successfully able to induce frustration (via measurable skin conductance responses) in the majority of trials. The mean recovery half-time of participants in the first trial adaptive condition was significantly longer than that of the control. This was attributed to a possibility of a large chromatic difference between the adaptive and control colour schemes, habituation and prediction, causal association of adaptation to the frustrating stimulus, as well as insufficient subtlety in the transition and visual look of the adaptive interface. The study produced findings and guidelines that will be crucial in the future design of adaptive affective user interfaces.
82

Design and Evaluation of a Knee-Extension-Assist

Spring, Alexander January 2011 (has links)
Quadriceps muscle weakness is a condition that can result from a wide variety of causes, from diseases like polio and multiple sclerosis to injuries of the head and spine. Individuals with weakened quadriceps often have difficulty supplying the knee-extension moments required during common mobility tasks. Existing powered orthoses that provide an assistive knee-extension moment are large and heavy, with power supplies that generally last less than two hours. A new device that provides a knee-extension-assist moment was designed to aid an individual with quadriceps muscle weakness to stand up from a seated position, sit from a standing position, and walk up and down an inclined surface. The knee-extension-assist (KEA) was designed as a modular component to be incorporated into existing knee-ankle-foot-orthoses (KAFO). The KEA consists of three springs that are compressed, as the knee is flexed under bodyweight, by cables that wrap around a sheave at the knee. The KEA returns the stored energy from knee flexion as an extension moment during knee extension. During swing or other non-weight bearing activities, the device is disengaged from the KAFO by decoupling the sheave from the KAFO knee joint, allowing free knee joint motion. A prototype was built and mechanically tested to determine KEA behaviour during loading and extension and to ensure proper KEA function. For biomechanical evaluation, able-bodied subjects used the prototype KEA while performing sit-to-stand, stand-to-sit, ramp ascent, and ramp descent tasks. The KEA facilitated sitting and standing, providing an average of 53 % of the required extension moment for the two participants, which allowed one participant to reduce quadriceps usage by 38 % and the other to perform sit-to-stand in a slower and more controlled manner that was not possible without the KEA. KEA use during ramp gait caused an overall increase in quadriceps activation by 76 %, on average, with use. Future efforts will be made to modify the design to improve functionality, especially for ramp gait, and to reduce device size and weight.
83

Automatic segmentation of skin lesions from dermatological photographs

Glaister, Jeffrey Luc January 2013 (has links)
Melanoma is the deadliest form of skin cancer if left untreated. Incidence rates of melanoma have been increasing, especially among young adults, but survival rates are high if detected early. Unfortunately, the time and costs required for dermatologists to screen all patients for melanoma are prohibitively expensive. There is a need for an automated system to assess a patient's risk of melanoma using photographs of their skin lesions. Dermatologists could use the system to aid their diagnosis without the need for special or expensive equipment. One challenge in implementing such a system is locating the skin lesion in the digital image. Most existing skin lesion segmentation algorithms are designed for images taken using a special instrument called the dermatoscope. The presence of illumination variation in digital images such as shadows complicates the task of finding the lesion. The goal of this research is to develop a framework to automatically correct and segment the skin lesion from an input photograph. The first part of the research is to model illumination variation using a proposed multi-stage illumination modeling algorithm and then using that model to correct the original photograph. Second, a set of representative texture distributions are learned from the corrected photograph and a texture distinctiveness metric is calculated for each distribution. Finally, a texture-based segmentation algorithm classifies regions in the photograph as normal skin or lesion based on the occurrence of representative texture distributions. The resulting segmentation can be used as an input to separate feature extraction and melanoma classification algorithms. The proposed segmentation framework is tested by comparing lesion segmentation results and melanoma classification results to results using other state-of-the-art algorithms. The proposed framework has better segmentation accuracy compared to all other tested algorithms. The segmentation results produced by the tested algorithms are used to train an existing classification algorithm to identify lesions as melanoma or non-melanoma. Using the proposed framework produces the highest classification accuracy and is tied for the highest sensitivity and specificity.
84

Decision Support Tools for Strategic Policy Analysis

Su, Xin 22 January 2006 (has links)
New or improved decision analysis tools are developed in this thesis to address strategic policy analysis with specific focus on two topics: strategic conflict analysis and region-performance comparisons. A strategic conflict refers to a situation in which two or more decision makers (DMs) are to make a decision that affects issues over which they have different preferences. Various forms of strategic conflict exist all around us, in areas such as environmental management, international relations, economic competition, and relationships among individuals. The graph model for conflict resolution (GMCR) is an advanced and comprehensive tool to systematically study strategic conflicts. A well-known decision tool, the analytic network process (ANP) is adapted for use in strategic conflict analysis and a comparison of the performance of ANP with GMCR is carried out. Both methods are applied to an international trading conflict between the United States and China over the importation of television sets into the US in order to gain strategic insights about this dispute using the two different but complementary approaches. A country's overall performance comparison with respect to different kinds of indices such as economic, environmental and political indices constitutes another interesting topic for strategic policy analysis. An index aggregation approach is proposed to compare BRICSAM countries, a populous rapidly-growing economic group of nations consisting of Brazil, Russia, India, China, South Africa, ASEAN (Association of South-East Asian Nations), and Mexico with G7 (Group of Seven), the most developed country club including Canada, France, Italy, Japan, Germany, United Kingdom and the United States. A data-envelopment-analysis (DEA) based approach is proposed to aggregate different ranking indices for BRICSAM and the G7 countries. The proposed method can provide a fair overall assessment of a country's standing by maximizing its possibility of obtaining the best evaluation score. Finally, a framework to carry out generic strategic analysis for regions' competence analysis is designed based upon the theory of generic strategic analysis proposed by Porter (1980). This is a well-known approach for use in business competence analysis. The basic idea is to carry out generic strategic analysis in policy studies and two decision tools, DEA and the analytic hierarchy process, are employed to quantify the analysis of competence efficiency and potentiality, respectively. A case study of the competence analysis of provinces in China is used to demonstrate the analysis procedure.
85

Probabilistic Robust Design For Dynamic Systems Using Metamodelling

Seecharan, Turuna Saraswati January 2007 (has links)
Designers use simulations to observe the behaviour of a system and to make design decisions to improve dynamic performance. However, for complex dynamic systems, these simulations are often time-consuming and, for robust design purposes, numerous simulations are required as a range of design variables is investigated. Furthermore, the optimum set is desired to meet specifications at particular instances in time. In this thesis, the dynamic response of a system is broken into discrete time instances and recorded into a matrix. Each column of this matrix corresponds to a discrete time instance and each row corresponds to the response at a particular design variable set. Singular Value Decomposition (SVD) is then used to separate this matrix into two matrices: one that consists of information in parameter-space and the other containing information in time-space. Metamodels are then used to efficiently and accurately calculate the response at some arbitrary set of design variables at any time. This efficiency is especially useful in Monte Carlo simulation where the responses are required at a very large sample of design variable sets. This work is then extended where the normalized sensitivities along with the first and second moments of the response are required at specific times. Later, the procedure of calculating the metamodel at specific times and how this metamodel is used in parameter design or integrated design for finding the optimum parameters given specifications at specific time steps is shown. In conclusion, this research shows that SVD and metamodelling can be used to apply probabilistic robust design tools where specifications at certain times are required for the optimum performance of a system.
86

Integrated Fluorescence Detection System for Lab on a Chip Devices

Mo, Keith January 2007 (has links)
This thesis focuses on the design of a versatile, portable, and cost-effective fluorescence detection system for LOC devices. Components that are widely available are used, such as LEDs for excitation and a microcontroller for processing. In addition, a photoresistor is tested for the feasibility of being used as a fluorescence detector, instead of the more commonly used photomultiplier tubes. The device also focuses on upgradeability and versatility, meaning that most of the major components can be replaced as long as power requirements remain unaffected. This allows for future additions to the device once they are available, as well as giving the user the power to choose which add-ons are needed since not all users may have the same requirements. The performance of the device after testing with fluorescein dyes and stained yeast cells indicate that it is capable of executing simple tasks, such as determining the presence and concentration of an analyte if given a sufficient amount. It also provided similar readings to commercial fluorescence analysers, which proves its ability to function as a fluorescence detector device. The thesis also proposes a MEMS diffraction grating that can be used for wavelength tuning. By being able to selectively measure across a range of wavelengths, the capability of the device is increased. Examples include being able to detect multiple fluorescent emissions, which will complement the multicoloured excitation LED nicely. In addition, the device will not be limited to a predetermined set of filters. This effectively allows more fluorescent dyes to be used with the device since any wavelength in the visible range can be selectively filtered for. Simulations of the proposed diffraction grating were performed in ANSYS to confirm the validity of the calculated values. In addition, tests were performed on a slide fabricated with diffraction gratings using values as close to the calculated values as possible. All of the results indicate that there is great promise in the proposed diffraction grating design and that it should be further investigated.
87

Cell Manipulations with Dielectrophoresis

Lin, James Ting-Yu January 2007 (has links)
Biological sample analysis is a costly and time-consuming process. It involves highly trained technicians operating large and expensive instruments in a temperature and dust controlled environment. In the world of rising healthcare cost, the drive towards a more cost-effective solution calls for a point-of-care device that performs accurate analyses of human blood samples. To achieve this goal, today's bulky laboratory instruments need to be scaled down and integrated on a single microchip of only a few square centimeters or millimeters in size. Dielectrophoresis (DEP), a phenomenon where small particles such as human blood cells are manipulated by non-uniform electric fields, stands to feature prominently in the point-of-care device. An original device that enhances DEP effect through novel geometry of the electrodes is presented. When activated with two inverting sinusoidal waveforms, the novel-shaped electrodes generate horizontal bands of increasing electric fields on the surface of the microchip. With these bands of electric fields, particles can be manipulated to form a straight horizontal line at a predictable location. Experimental results showing the collection, separation, and transportation of mammalian cells are presented. A strategy for simultaneous processing of two or more types of particles is also demonstrated. With capabilities for an accurate position control and an increased throughput by parallel processing, the novel microchip device delivers substantial improvements over the existing DEP designs. The research presented here explores the effects of novel electrode geometries in cell manipulations and contributes to the overall progress of an automated blood analysis system.
88

Congestion Control for Adaptive Satellite Communication Systems with Intelligent Systems

Vallamsundar, Banupriya January 2007 (has links)
With the advent of life critical and real-time services such as remote operations over satellite, e-health etc, providing the guaranteed minimum level of services at every ground terminal of the satellite communication system has gained utmost priority. Ground terminals and the hub are not equipped with the required intelligence to predict and react to inclement and dynamic weather conditions on its own. The focus of this thesis is to develop intelligent algorithms that would aid in adaptive management of the quality of service at the ground terminal and the gateway level. This is done to adapt both the ground terminal and gateway to changing weather conditions and to attempt to maintain a steady throughput level and Quality of Service (QoS) requirements on queue delay, jitter, and probability of loss of packets. The existing satellite system employs the First-In-First-Out routing algorithm to control congestion in their networks. This mechanism is not equipped with adequate ability to contend with changing link capacities, a common result due to bad weather and faults and to provide different levels of prioritized service to the customers that satisfies QoS requirements. This research proposes to use the reported strength of fuzzy logic in controlling highly non-linear and complex system such as the satellite communication network. The proposed fuzzy based model when integrated into the satellite gateway provides the needed robustness to the ground terminals to comprehend with varying levels of traffic and dynamic impacts of weather.
89

Interface Design for Sonobuoy System

Chen, Huei-Yen Winnie January 2007 (has links)
Modern sonar systems have greatly improved their sensor technology and processing techniques, but little effort has been put into display design for sonar data. The enormous amount of acoustic data presented by the traditional frequency versus time display can be overwhelming for a sonar operator to monitor and analyze. The recent emphasis placed on networked underwater warfare also requires the operator to create and maintain awareness of the overall tactical picture in order to improve overall effectiveness in communication and sharing of critical data. In addition to regular sonar tasks, sonobuoy system operators must manage the deployment of sonobuoys and ensure proper functioning of deployed sonobuoys. This thesis examines an application of the Ecological Interface Design framework in the interface design of a sonobuoy system on board a maritime patrol aircraft. Background research for this thesis includes a literature review, interviews with subject matter experts, and an analysis of the decision making process of sonar operators from an information processing perspective. A work domain analysis was carried out, which yielded a dual domain model: the domain of sonobuoy management and the domain of tactical situation awareness address the two different aspects of the operator's work. Information requirements were drawn from the two models, which provided a basis for the generation of various unique interface concepts. These concepts covered both the needs to build a good tactical picture and manage sonobuoys as physical resources. The later requirement has generally been overlooked by previous sonobuoy interface designs. A number of interface concepts were further developed into an integrated display prototype for user testing. Demos created with the same prototype were also delivered to subject matter experts for their feedback. While the evaluation means are subjective and limited in their ability to draw solid comparisons with existing sonobuoy displays, positive results from both user testing and subject matter feedback indicated that the concepts developed here are intuitive to use and effective in communicating critical data and supporting the user’s awareness of the tactical events simulated. Subject matter experts also acknowledged the potential for these concepts to be included in future research and development for sonobuoy systems. This project was funded by the Industrial Postgraduate Scholarships (IPS) from Natural Science and Engineering Research Council of Canada (NSERC) and the sponsorship of Humansystems Inc. at Guelph, Ontario.
90

Soil Moisture Estimation by Microwave Remote Sensing for Assimilation into WATClass

Kwok, Damian January 2007 (has links)
This thesis examines the feasibility of assimilating space borne remotely-sensed microwave data into WATClass using the ensemble Kalman filter. WATClass is a meso-scale gridded hydrological model used to track water and energy budgets of watersheds by way of real-time remotely sensed data. By incorporating remotely-sensed soil moisture estimates into the model, the model’s soil moisture estimates can be improved, thus increasing the accuracy of the entire model. Due to the differences in scale between the remotely sensed data and WATClass, and the need of ground calibration for accurate soil moisture estimation from current satellite-borne active microwave remote sensing platforms, the spatial variability of soil moisture must be determined in order to characterise the dependency between the remotely-sensed estimates and the model data and subsequently to assimilate the remotely-sensed data into the model. Two sets of data – 1996-1997 Grand River watershed data and 2002-2003 Roseau River watershed data – are used to determine the spatial variability. The results of this spatial analysis however are found to contain too much error due to the small sample size. It is therefore recommended that a larger set of data with more samples both spatially and temporally be taken. The proposed algorithm is tested with simulated data in a simulation of WATClass. Using nominal values for the estimated errors and other model parameters, the assimilation of remotely sensed data is found to reduce the absolute RMS error in soil moisture from 0.095 to approximately 0.071. The sensitivities of the improvement in soil moisture estimates by using the proposed algorithm to several different parameters are examined.

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