This research is aimed to study the storage tank design parameters effects on the efficiency of the large solar hot water system. Detailed CFD simulation for the storage tank coupled with TRNSYS program simulation for the entire solar hot water system will be performed to study the system performance under various thermal stratification baffles design for the storage tank. The study is made for three representative cities of Taiwan by input their typical-meteorological-year data (TMY data). The results indicate the performance of a large solar hot water system can be significantly improved with proper designed thermal stratification baffles in the storage tank.

This thesis describes the development of the Texas A&M University Autonomous Helicopter System and the integration of obstacle avoidance capabilities into that system. The helicopter system, composed of a Bergen Observer helicopter and a Rotomotion Autonomous Flight Control System (AFCS), was developed as a platform to support the development of the obstacle avoidance system through integration of sensors and onboard processing capabilities. The system has proven in various flight tests that it has the capability to autonomously hover and fly to user defined GPS waypoints. The obstacle avoidance algorithm has been proven in simulations involving an interface with the Rotomotion AFCS and the flight simulation software they created to facilitate the development of that system. The helicopter has also demonstrated appropriate responses to sensor input commensurate with the obstacle avoidance algorithm. Full avoidance tests were unable to be performed due to hardware malfunctions inherent in the obstacle avoidance sensors.

As the rapid development of the rail transportation industry, rail transportation becomes more popular as a component of urban public transport systems, but the fallen obstacle(s) from the rail platform becomes the terrible hidden danger for the rail transportation. As an enclosed public transport systems, rail transportation creates gathered crowd both on board and on the platform. Although railway is the safest form of land transportation, it is capable of producing lots of casualties, when there is an accident.There are several conventional systems of obstacles detection in platform monitoring systems like stereo visions, thermal scanning, and vision metric scanning, etc. As the traditional detection systems could not achieve the demand of detecting the obstacles on the rail within the platform. In this thesis, the author designs a system within the platform based on laser sensors, virtual instruments technology, and image processing technology (machine vision) to increase the efficiency of detection system. The system is useful for guarantying the safety of rail vehicle when coming into the platform and avoid obstacle(s) on the rail fallen from the platform, having a positive impact on traffic safety to protect lives of people.The author used LabVIEW software to create a simulation environment where the input blocks represent the functionalities of the system, in which simulated train detection and fallen object detection. In this thesis, the author mainly focuses on fallen object detection. For fallen object detection, the author used 2D image processing method to detect obstacle(s), so the function is, before the rail vehicle comes into the platform, the system could detect whether there is fallen obstacle(s) on the rail within the platform, simultaneously categorize size of the obstacle(s), and then alarm for delivering the results.

This thesis presents an indoor obstacle avoidance system for car-like mobile robot. The system consists of stereo vision, map building, and path planning. Stereo vision is performed on stereo images to create a geometric map of the environment. A fast sparse stereo approach is employed. For different areas of the image there are different optimal values of disparity range. A multi-pass method to combine results at different disparity range is proposed. To reduce computational complexity the matching is limited to areas that are likely to generate useful data. The stereo vision system outputs a more complete disparity map. Abstract Map building involves converting the disparity map into map coordinates using triangulation and generating a list of obstacles. Occupancy grids are built to aid a hierarchical collision detection. The fast collision detection method is used by the path planner. Abstract A steering set path planner calculates a path that can be directly used by a car-like mobile robot. An adaptive approach using occupancy grid information is proposed to improve efficiency. Using a non-fixed steering set the path planner spends less computation time in areas away from obstacles. The path planner populates a discrete tree to generate a smooth path. Two tree population methods were trialled to execute the path planner. The methods are implemented and experimented on a real car-like mobile robot.

With modern day computer power, developing intelligent vehicles is fast becoming a reality. An Intelligent Vehicle is a vehicle equipped with sensors and computing that allow it to perceive the world around it, and to decide on appropriate action. Vision cameras are a good choice to sense the environment. One key task of the camera in an intelligent vehicle is to detect and localise the obstacles, which is the preparation of path planning. Stereo vision based obstacle detection is used in this research. It does not analyse semantic meaning of image features, but directly measures the 3-D coordinates of image pixels, and thus is suitable for obstacle detection in an unknown environment. In this research, a novel correlation based stereo vision method is developed which greatly improves its accuracy while maintaining its real-time performance. Since a vision system provides a large amount of data, extracting refined information may sometimes be complex. In obstacle detection tasks, the purpose is to distinguish the obstacle pixels from the ground pixels in the disparity image. V-Disparity image approach is used in this research to detect the ground plane, however this approach relies heavily on sufficient road features. In this research, a correlation method to locate the ground plane in the disparity image, even without significant road features, is developed. Moreover, traditional V-Disparity images have difficulties detecting non-flat ground, thus having limited applications. This research also develops a method to detect non-flat ground using V-Disparity images, thus greatly widening its application.

In today's digital (electronics) world, people's desire for electronic goods that ease their life at work, and leisure is increasing the complexity of the products of the embedded systems industry. For example, MP3 players for listening to music and cell phones for communicating with people.The gap between the hardware and software parts of embedded systems is being reduced by the use of System Level Design Languages (SLDL) that can model both hardware and software simultaneously. One such SLDL is SpecC.In this thesis, a SpecC model of a Real Time Operating System (RTOS) is constructed. It is shown how RTOS features can be incorporated into a SpecC model. The model is used to develop an application involving a robot avoiding obstacles to reach its destination. The RTOS model operates similar to the actual RTOS in the robot.The application includes a testbench model for the robot, including features such as interrupts, sonar sensors and wheel pulses, so that its operation closely resembles the actual robot. The sensor model is programmed to generate the values from the four sensor receivers, similar to the behaviour of the sensors on the actual robot. Also the pulses from the wheels and associated interrupts are programmed in the model so that it resembles the interrupts and wheel pulses present on actual robot.

Thesis (M.A.)--Western Michigan University, 2003. / Includes bibliographical references (leaves 43-46). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.A.)--Western Michigan University, 2003. / Includes bibliographical references (leaves 43-46).

Falls are the leading cause of injuries among Canadians who are aged at 65 years and over. The assessment of dynamic stability has been proved as an effective method to identify fall-prone elderly individuals, which is essential to fall prevention. Tai Chi has been recommended as an effective exercise to prevent falls by the American Geriatric Society and British Geriatric Society. It is important to examine dynamic stability among Tai Chi practitioners and to explore the mechanisms of the effects of Tai Chi practice on fall prevention. This study examined the dynamic postural stability which is assessed by center of mass (COM) range of motion, COM - center of pressure (COP) separation, and temporospacial measures of gait during obstacle-walking in two groups: Tai Chi group and healthy controls. Fifteen participants in each group were asked to complete two walking conditions, level walking and 20cm-obstacle walking. Results showed that when compared with Tai Chi group, control group adopted a conservative crossing strategy with a significantly smaller crossing stride, higher heel clearance, and smaller pre horizontal distance to make obstacle crossing as safe as possible. This conservative strategy indicates the inability to cross obstacle casually and it may be associated with the decline in muscle strength and proprioception. It also showed that Tai Chi practitioners displayed a significantly larger COM range of motion in both anteroposterior (AP) and mediolateral (ML) direction (p<0.05) and a significantly larger COM-COP separation in ML direction (p <0.01), as compared with control group. The larger range of motion of COM and distance between COM and COP indicates that Tai Chi practitioners have a better ability to tolerate unsteadiness, which means if perturbation occurs, Tai Chi practitioners have a larger range to shift COM in the boundary of base of support.

The objective of this research work is to enhance the understanding of heat transfer and pressure loss in heated tubes equipped with flow obstacles by experimentally investigating the axial and circumferential distributions of convective heat transfer in a heated tube, complemented by pressure loss and velocity measurements in an adiabatic pipe flow. The heat transfer experiments employed refrigerant R-134a as the working fluid with a Reynolds number range of 14,000 to 97,000. Three types of flow obstructions were investigated: eccentric cylinders with flat and rounded ends and annular obstacles, each having a flow blockage of either 0.15 or 0.3. The axial distribution of heat transfer coefficient was measured downstream from the downstream end of the obstruction over a distance of 3 to 70 tube diameters. The experimental data indicate that heat transfer augmentation downstream from the flow obstructions depends on the obstructed area, the flow Reynolds number, the distance from the flow blockage and, to a lesser extent, the shape and the circumferential location of the obstruction. Our experiments confirm the previous findings that heat transfer augmentation (compared to the bare tube heat transfer case) decreases with an increase of flow Reynolds number. It was found that heat transfer augmentation typically extends up to 30 diameters downstream of a flow obstacle. An improved prediction method that correlates the obstructed flow area, Re number and the distance from the trailing edge of the obstacle has been derived. Pressure loss and velocity measurements were also collected for a flow Reynolds number range from 11,000 to 65,000, for flat ended (blunt) and rounded cylinders with a flow blockage ratio of 0.3 and a blunt cylinder with a flow blockage ratio of 0.15. The results showed that blockage ratio and shape of flow obstacle affect the obstacle pressure loss coefficient significantly and they confirm previous research findings that obstacle pressure loss coefficient decreases with an increase of bulk Reynolds number. Measurements of the reattachment length downstream from flow obstacles indicated that the reattachment length for three-dimensional turbulent flow around square-shaped cylinders was significantly shorter than two-dimensional flow over a backward-facing step. An important finding of the current investigation is that, for the flow range investigated, heat transfer augmentation could not be correlated with the local pressure loss coefficient of the obstruction, which differs from the smooth heated channel case where the Reynolds analogy usually applies. Additionally, to assess the capabilities of the widely used k- turbulence model, some CFD simulations were performed. The CFD results were generally in satisfactory agreement with the experimental data; however, near the obstacle, close to the separation and recirculation areas, the agreement with the experimental data was less satisfactory. The current research can be applied to the design and optimization of spacers and appendages of nuclear fuel elements, as well as serve for the improvement of state of the art computer codes employed in the safety assessment of nuclear reactors.