In-process turbine monitoring has been a subject of research since the advent of gas turbines; however, it is difficult because it requires precision measurements to be made at high speeds and temperatures. The measurement of turbine blade tips is especially intriguing because of the potential it holds to greatly increase the efficiency of engine operation and maintenance. Tip-to-casing clearance is one of the major sources of inefficiency in a turbine and monitoring of this clearance would allow active tip-clearance control systems to be implemented. Also, analysis of engine wear through vibration monitoring may increase the effectiveness of engine maintenance and repair. A sensor recently developed at Georgia Tech could answer this challenge. The sensor operates by measuring the phase change of reflected microwaves to measure blade tip displacement. It is robust even in the harsh turbine environment. However, in sensor measurements, the microwave beam pattern causes a phenomenon called spatial filtering to occur, which may compromise the precision of measurements. Since the beam is not a thin line reflecting off a single point on the turbine blade, measurements are a weighted average of measurements along the entire surface within the field-of-view of the sensor. The net effect is a blurred measurement. In measuring turbine blades, only the tip is vital, so the blurring in between blades is not extremely detrimental. However, changing measurement geometry affects the amount of spatial filtering and hence the accuracy of the measurement. This thesis presents a detailed analysis of this phenomenon and especially its effect on turbine blade tip clearance measurements. A design of experiments is presented to qualitatively understand the effect of geometric factors on tip measurements. Along with experimentation, a robust, three-dimensional, ray-tracing, electromagnetic model is presented which was developed to further understand spatial filtering and to analyze specific geometric factors in the measurement of turbine blades. The research shows that microwave measurements may still be made to sufficient accuracy even considering the effect of spatial filtering, and by quantifying spatial filtering in measurements, it may be possible in to glean additional useful data from measurements.

At micrometer length scales of material removal, size effect is observed in mechanical micro-cutting where the energy per unit volume i.e. specific cutting energy increases nonlinearly as the uncut chip thickness is reduced from several hundred microns to a few microns (or less). There is no consensus in the literature on the cutting mechanism that causes this size effect. Noticeable discrepancy is also observed in the surface roughness produced at small feeds in micro-turning between the theoretical and the measured roughness. To date, there has been little effort made to develop a detailed process model for micro-cutting to accurately predict the size effect in specific cutting energy, and to develop a fundamental understanding of surface generation at the low feeds typical of micro-cutting processes. The main objective of this thesis is therefore to develop a predictive process model of micro-cutting of ductile metals that is capable of accurately predicting the size effect in specific cutting energy based on strain gradient based material strengthening considerations. In addition, this thesis attempts to explain the discrepancy between the theoretical and measured surface roughness at small feeds in micro-turning via a model that accounts for the size effect due to material strengthening. A coupled thermo-mechanical finite element model formulation incorporating strain gradient plasticity is developed to simulate orthogonal micro-cutting process. The thermo-mechanical model is experimentally validated in orthogonal micro-cutting of a strain rate insensitive aluminum alloy Al5083-H116. The model is then used to analyze the contributions of two major material strengthening factors to the size effect in specific cutting energy: strain gradient and temperature. The effects of cutting edge radius on the specific cutting energy and its role relative to the material length scale arising from strain gradient plasticity are also examined. A surface roughness model for micro-turning that incorporates the effects of kinematic roughness, cutting edge roughness and surface roughening due to plastic side flow is developed and shown to explain the observed discrepancy between the theoretical and measured surface roughness in micro-cutting. In addition, the model is found to accurately capture the increase in surface roughness at very low feeds.

Ninty three yellowfin tuna, Thunnus albacares, the fork length ranged from 80 to 168 cm were collected from the waters around Seychelles by two longline fishing vessels from April to December in 2006. The muscle and liver samples were analyzed for total mercury (THg) and organic mercury (OHg) concentrations.The concentrations of THg and OHg of the muscle were similar to previous studies. The concentrations of THg and OHg form the muscles and livers were positive-linearly regressed with the fish of Fork Length larger than 113 cm (big fish group), but only THg concentration of muscle was negative- linearly regressed 80- 112 cm (small fish group). Such patterns were first found in yellowfin tuna. It might be related to the ¡§growth rate¡¨ . Only one THg concentration of liver were over the standard set by the European Commission Decision (1 mg / kg THg wet wt.), other samples were in accordance with standard set by the European Commission Decision and the US-FDA food safty standard (1 mg / kg MeHg wet wt.). According to the dietary recommendations set by the Department of Health, Executive Yuan, yellowfin tuna can replace 86% animal protein source per week of people.

This study investigated effects of the process parameters on the forging load and metal flow pattern during forging and thread-rolling these two process of LZ91 magnesium alloy small size screw by the finite element analysis. At first, Compression tests were carried out under various forming temperatures to study the flow stress. Then, FEM software DEFORM-2D is adopted to simulate forging and thread-rolling processes of small screw to analyze the formability and parameters. In one of this study, there are two stages in forging process, and found out that up-die velocity, temperatures and friction factors will affect the product quality and appearance; on the other part, it investigated the effect of friction factor and temperature under thread-rolling process, and found out that effective stress, effective strain, metal flow and height of thread will be affected. In addition, conduct forging and thread-rolling experiments by using universal testing machine with the mold self-designed, and MoS2 of lubricant, and comparing the analytical results to verify the suitability and accuracy of FEM for forging process. Finally, according to the analysis result of this study, engineers can take it as reference.

In the Thesis, we propose a mechanism to dynamically adjust video parameters in an intelligent video surveillance network. Whenever there is an alarm or network encounters congestion, we could adjust video parameters including Frames per Second (FPS), Quality, and Picture Size to adapt to network bandwidth. For examples, we can adjust FPS when an alarm exists in the surveillance system; we can adjust the Quality or Picture Size by counting the total number of video packets received per second to obtain a smooth video when network is congested To demonstrate the proposed schemes, we implement these three adjustable parameters, Quality, Picture size, and FPS on a Linux platform. To do this, we establish a new HTTP connection from a client to a camera and then we develop the corresponding control messages issued by the client in order to change the video parameters. In addition, we implement a video recovery mechanism by measuring the differences in arrival time between every packet (referred to as diff). Finally, we observe with our proposed scheme whether the video quality can be smoother under different background traffics. In the video recovery mechanism, we utilize diff to decide whether a higher quality picture should be persisted or downgraded to a lower quality picture to avoid packet loss under network congestion.

Product design affects many aspects of people¡¦s life. This research use qualitative and quantitative methods, and focus on how simple design cause different consumer responses. First of all, we process a content analysis aiming for household and digital product, and then we conduct the definition and characteristics of simple design. Second, we use experimental design to figure out the pattern of consumer responses to product design both psychological and physical. For psychological responses, we observe the consumer expectation and satisfaction in product appearance, assortment size and functional information; we also exam the different decision making tendency (Maximizer & Satisficer) in consumer approach behavior. According to our research, we conclude that the required elements of simple design are (1) Single Color, (2) Unique Personality, (3) Simple Shapes, (4) Practical Function, (5) Easy to Use, (6) Match, (7) Materials, (8) Aesthetics and (9) Culture & Emotion. For product external appearance, there is high expectation for simple design, and also satisfaction still has a big room to improve. To be more specific, in the aspects of attention drawing, unique symbol and ergonomic is the biggest gap between expectation and satisfaction. In the part of assortment size, simple design causes a higher expectation when the size is large. However, satisfaction did not drop as previous studies suggested, it remains indifferent which could be the suggestion for future product development. In function information, it plays a important role in digital product which means mainly simple designed appearance can only achieve limited benefits. In behavioral response, satisfaction and approach behavior have positive relation, and the responses of store are apparently stronger than the responses of single product. In different decision making tendency, product personality, attention drawing and assortment size are significant, but there is no clear result for function information.

The aim of this study was to observe the properties of a spray field, with micro particle image velocimetry (£gPIV) and holographic interferometric particle imaging (IPI) employed for the imaging and analysis of the global spray field. The experiment adopted different nozzle diameters (dj = 200 £gm, and dj = 500 £gm) and different values of gauge pressure (£GP = 300 kPa, £GP = 500 kPa, and £GP = 700 kPa) as the main parameters, and DI (distilled) Water as the working medium. The study was divided into two parts. The first part used the £gPIV system to observe the two-dimensional global visualization of spray field distribution and spray angle from each nozzle under different values of gauge pressure (£GP). The flow velocity distribution and variations (axial velocity, and impact velocity) of the global spray frame were also measured. As the nozzle diameter would determine the distribution of spray droplets, the second part adopted the IPI system to measure and explore the atomized droplet sizes from each nozzle under different values of gauge pressure (£GP), whereby drop size histograms were created through statistical analysis.

Compression tests along the rolling and normal direction of AZ31B plate materials under 10 s strain rate were performed at room temperature to understand the effect of grain size on the formation of deformation twins. When compressed along the rolling direction, tension twins were formed in bands. Within the twin bands, nearly all grains contained tension twins, irrespective of grain size. And outside the bands, no twin was found. Under this deformation condition, grain size has no effect on the formation of tension twins. The reason for this is due to the fact that the formation of a tension twin can trigger the formation of tension twin in the neighboring grain, irrespective of the neighboring grain size. When compressed along the normal direction, no twin band was formed, and compression twins were formed evenly in the specimens. Under this deformation condition, it was found that the larger the grain size, the higher the fraction of grains which contained compression twins. This result indicates that compression twins are easier to be formed in the large grains.

Driven by the ambition for ubiquitous networking, wireless networks had gained substantial technical advances in recent years. Using radio signals in air as data links, wireless networks can get rid of the tangling of wired cables. However, due to the inherent limitations of wireless channels and legacy protocol design, users of wireless networks today still suffer from the problems on low bandwidth and high error rates. The seven-layer Open System Interconnection (OSI) model was originally designed with wired network environments in mind. Following the seven-layer OSI model, each layer is responsible for handling specific tasks without communicating with each other. Due to the relative stability of wired channels, the strictly-layered approach works well in wired network environments. However, its adequacy is a controversy in wireless environments, since wireless networks have completely different characteristics from its wired counterparts. In wireless environments, channel conditions are highly time-varying and are affected by many factors. External interference or signal degradation may lead to severe packet loss. Even signal-to-noise ratios are fine, transmissions may still fail due to collisions when contention-based MAC protocols are adopted. Conventional protocols developed with wired network environments in mind cannot appropriately response to the characteristics of wireless channels and may make wrong reactions. For these reasons, a flexible framework to capture the rapid change conditions of wireless channels and respond to them immediately is necessary. In this dissertation, we design a cross-layer framework with the consideration of wireless network characteristics. By the coordination between the involved layers, the cross-layer framework can adapt to wireless channel conditions and significantly improve QoS in wireless networks. In order to reduce collision probabilities in wireless networks, we propose a novel protocol named Wait-and-Transmit, which effectively alleviates contentions in wireless networks. By reducing collision probabilities of wireless networks, transmission delays can be shortened and throughputs can be significantly improved. Aiming at the transmission paths containing at least one wireless link, a flexible and efficient cross-layer transmission scheme is also present in this dissertation, which separates the rapid change conditions such as collision probabilities from the relatively stable conditions and well responds to these changes. The proposed approaches significantly improve the performance of wireless networks. We believe that these approaches can contribute to the development of wireless networking.

A set of experiments was designed and performed to gain a fundamental understanding of various aspects of the segregated network concept. The electrical and mechanical properties of composites made from commercial latex and carbon black are compared with another composite made from a polymer solution. The percolation threshold of the emulsion-based composite is nearly one order of magnitude lower than that of the solution-based composite. The segregated network composite also shows significant improvement in both electrical and mechanical properties with low carbon black loading, while the solution-based composite achieves its maximum enhancement at higher carbon black loading (~25wt%). The effect of the particle size ratio between the polymer particle and the filler was also studied. In order to create a composite with an extremely large particle size ratio (> 80,000), layer-by-layer assembly was used to coat large polyethylene particles with the carbon black. Hyper-branched polyethylenimine was covalently grafted to the surface of polyethylene to promote the film growth. The resulting composite has a percolation threshold below 0.1 wt%, which is the lowest percolation threshold ever reported for a carbon-filled composite. Theoretical predictions suggest that the actual percolation threshold may be lower than 0.002 wt%. Finally, the effect of the emulsion polymer modulus on the segregated network was studied. Monodispersed emulsions with the different glass transition temperature were used as the matrix. The composites made using the emulsion with higher modulus show lower percolation threshold and higher conductivity. Higher modulus causes tighter packing of carbon black between the polymer particles. When the drying temperature was increased to 80°C, the percolation thresholds became closer between some systems because their moduli were very close. This work suggests modulus is a variable that can be used to tailor percolation threshold and electrical conductivity, along with polymer particle size.