This study is to analyze and test the extrusion process of a hollow spur gear and a solid helical product with magnesium alloy. In the hollow spur gear part, firstly, a design criterion to determine the forming parameters is proposed. Then, the Finite Element Analysis is used to simulate the flow pattern of the billet from separating channel, welding chamber to die bearing part. From a series of simulation results, the effect of separating channel length, mandrel entrance angle, welding chamber height, etc. on the radial filling ratio, welding pressure, extrusion load, etc. are found. By using the Taguchi Methods, we can find the most important parameters. Finally, a better die geometry is designed to obtain a sound product. In the helical product part, the Finite Element Analysis is used to get the understandings of radical filling ratio of magnesium alloy in the helical zone. Then, a better die geometry is designed from the results of analyses. Finally, hot extrusion experiments of a hollow spur gear and a solid helical product are conducted. The experimental values of the extrusion load and the product¡¦s dimension are compared with the analytic values to verify the validity of the analytic models.

I present the results of a search for pair production of scalar top quarks (~t1) in an R-parity violating supersymmetric scenario using 322 pb_1 of pp collisions at ps = 1.96 TeV collected by the upgraded Collider Detector at Fermilab. I assume each ~t1 decays into a tau lepton and a b quark, with branching ratio B, and search for final states containing either an electron or a muon from a leptonic tau decay, a hadronically decaying tau lepton, and two or more jets. Two candidate events pass my final selection criteria, consistent with the expectation from standard model processes. I present upper limits on the cross section times branching ratio squared (~t1~t1)B2 as a function of the stop mass m(~t1). Assuming B = 1, I set a 95% confidence level limit m(~t1) > 153 GeV=c2. These limits are also fully applicable to the case of a pair produced third generation scalar leptoquark that decays into a tau lepton and a b quark.

Being located in subtropical area, the weather in Taiwan is hot and humid which imposing huge cooling load on buildings. Conventionally, central air-conditioning plants were designed using refrigerant compressors to make chilled water, and then pumped through the zone pumps to meet the cooling load, providing air-conditioning by Fan Coil Unit (FCU) or Air-Handling Units (AHU) by ductwork. To meet the varying cooling demand, two important systems were developed for energy savings, namely, the Variable Water Volume (VWV) system, and the Variable Air Volume (VAV) system, which has been widely adapted in Taiwan area. The working principle is mainly devoted to adjusting the volume of the chilled water and/or air volume delivered through inverter-driven pimps and fans to achieve energy saving. On the other hand, recently in Japan, an important energy-saving air-conditioning system has been developed which directly varying the refrigerant flow rate to meet the varying cooling demand by inverter-driven compressors, named VRV system. Comparative to the conventional air-conditioning system, the heat exchange mechanism of the VRV system has been effectively enhanced by direct exchange of the refrigerant and the cool air, which is in effect a combination of the VWV and VAV system. It provided huge energy saving potential for the application on buildings with moderate cooling loads, such as 100 USRT or so. It is the goal of this research project, to evaluate the performance of the VRV system in Taiwan¡¦s hot and humid climate, by performing full-scale experimental investigation so that energy savings effect can be validated quantitatively. Since VRV system is fairly new in Taiwan, the validation of the system performance under local weather condition is of particular importance. It is anticipated that through the changing of the operation conditions, such as different outdoor conditions, various partial load conditions, and different scheduling of the VRV system, the power consumption of the VRV vs. conventional system can be compared precisely and quantitatively. These experimental data will, in turn, provides valuable reference to the establishment of the building energy consumption index in Taiwan, which outwits the direct adoption of the foreign data such as from Japan, in achieving a much reliable database.

This study is aimed at understanding and comparing the organizational management system and performance among the TV center of Republic Of China's armed forces, and collects info of the multi-media units of the USAF and educational program production unit of the Open University of Kaohsiung to get a picture of the current status of those organizations pertaining to multi-media program production, and serves as a reference for the future development of the TV centers of ROC's armed forces. The research approach used there is characteristic-oriented. TV centers of the Army, Navy, and Air Force are the study objects. Through interview with members of each service's TV center and the Open Universality of Kaohsiung to gain more detail information to be used as reference. From the result to understand the organization, manpower, equipment investment, production quantities and contents, then further the study on those multi-media units of USAF and the Open Universality of Kaohsiung to induce two discussion topics:merging and outsourcing. The first issue is to discuss whether it's practicable for merging the TV centers of the services. The second issue is to find whether it's feasible for the programs to be outsourced. Finally I'd like to bring up the limitation, contribution and suggestion of this study.

Self compacting concrete (SCC) is first developed in Japan in the late 1980s in order to overcome the consolidation problems associated with the presence of congested reinforcement. It is also termed as a high performance concrete, as it can flow under its own weight and completely fill the formworks. As the fresh properties of SCC are quite important, mix design of a SCC is performed by considering various workability related fresh properties. Therefore, a well designed SCC should satisfy all requirements of a hardened concrete, besides its superior workability properties. The aim of this research is to assess the effects of some basic ingredients of SCC on the fresh properties of SCC. This will be performed by applying design of experiment techniques and obtaining significant statistical models, which will give valuable information about the effects of the model parameters on the rheology and fresh state characteristics of SCC. In this research program, four different variables / use of fly ash replacement, use of high range water reducing admixture (HRWRA), use of viscosity modifying admixtures (VMA) and water-cementitious material ratio, are considered as the variables of the experimental design. Central Composite Design (CCD), a design of experiment technique, is employed throughout the experimental program and a total of 21 mixtures of concrete are cast. Slump flow, V-funnel, L-box, sieve segregation, initial and final setting time tests are performed, furthermore / to investigate the effects of these variables to the rheology of SCC, relative plastic viscosity and relative yield stress, which are the parameters of Bingham Model are measured with the help of a concrete rheometer. As a result of the experimental program, the fresh state properties of SCC are expressed by mathematical equations. Those equations are then used in order to explain the effects of fly ash replacement, HRWRA and VMA concentration, and the w/cm ratio on the fresh state properties of SCC. According to the derived models, it is stated that the water-cementitious material ratio of the concrete mixture is the most effective parameter on the flowability and passing ability of SCC beside the other parameters utilized in this research as its coefficient was the highest in the related models.

The most basic property of a muscle is its ability to contract and produce force when stimulated. A muscle is mainly composed of cells consisting of myofibrils with its basic unit called as a sarcomere. A sarcomere is composed of actin and myosin responsible for the muscle contraction. The Hill-type muscle model is the most commonly used model to simulate the behavior of a muscle. A muscle can produce its maximum force at isometric conditions. The level of force produced in the muscle is determined by the the frequency of the signals from the CNS. The force production is also a function of force-muscle current velocity and force-muscle current length relations. A muscle contains two types of sensors / i.e. muscle spindle and golgi tendon organ, which give rise to the feedback control of the muscle length and muscle contraction velocity. In this study a 1-D model of a muscle is formed step by step in Simulink. In the models the muscle mechanics has been investigated and the results are compared with the previous works.

Silicon is commonly used in infrared (IR) imaging systems. The surface quality is an important issue in optics manufacturing since surface roughness affects optical performance of imaging systems. Surface quality of an optical component is determined by number of factor, including cutting parameters / cutting speed, depth of cut and feed in radial direction. In this thesis, an experimental study has been performed to investigate the relation between cutting parameters and average roughness of the surface of silicon. In the experiments, silicon specimens, which have a diameter of 50 mm, were face turned by using a 2-axis CNC single point diamond turning machine. The specimens were machined by using either constant spindle speed or constant cutting speed. Two different tools with rake angles of -15 degrees and -25 degrees were used. The attained surfaces were measured by using a white light interferometer, which has a resolution of 0.1nm. The experiments were designed according to the factorial design method, considering cutting parameters. The effects of cutting parameters and tool rake angles on surface quality of silicon were observed. The best average surface roughness obtained was about 1 nm which is quite better than the acceptable average surface roughness level of 25 nm.

Manufacturing of dies has been presenting greater requirements of geometrical accuracy, dimensional precision and surface quality as well as decrease in costs and manufacturing times. Although proper cutting parameter values are utilized to obtain high geometrical accuracy and surface quality, there may exist geometrical discrepancy between the designed and the manufactured surface profile of the die cavities. In milling process / cutting speed, step over and feed are the main cutting parameters and these parameters affect geometrical accuracy and surface quality of the forging die cavities. In this study, effects of the cutting parameters on geometrical error have been examined on a representative die cavity profile. To remove undesired volume in the die cavities, available cutting strategies are investigated. Feed rate optimization is performed to maintain the constant metal removal rate along the trajectory of the milling cutter during rough cutting process. In the finish cutting process of the die cavities, Design of Experiment Method has been employed to find out the effects of the cutting parameters on the geometrical accuracy of the manufactured cavity profile. Prediction formula is derived to estimate the geometrical error value in terms of the values of the cutting parameters. Validity of the prediction formula has been tested by conducting verification experiments for the representative die geometry and die cavity geometry of a forging part used in industry. Good agreement between the predicted error values and the measured error values has been observed.

The aim of the OPERA experiment is to verify the neutrino oscillation, directly measuring the appearance of from an initially pure beam produced at CERN. For this purpose OPERA detector is located underground Gran Sasso Laboratory(LNGS) 730 km away from CERN. The detector structure designed to be a hybrid system consisting of emulsion targets and electronic detectors. Total area of the emulsion targets in the OPERA detector is around 110000 m2 which needs fast and reliable automatic scanning systems. For this purpose, two dierent automatic scanning systems were developed in Japan and Europe. For now there are 12 scanning laboratories dedicated to the OPERA Experiment. The Emulsion Scanning Laboratory in the Physics department of METU is one of the scanning laboratories for the OPERA Experiment. The automatic scanning system in METU is European type which is using commercial hardware for easy construction and maintain. Also the laboratory has a unique feature in terms of experimental high energy physics laboratories. The emulsion scan- ning laboratory in METU is the

The purpose of this study was to contribute to the science education literature by describing how thought experiments vary in terms of the nature, purpose of use and reasoning resources behind during the solution of conceptual physics problems. Three groups of participants were selected according to the level of participants&rsquo / physics knowledge- low, medium, and high level groups- in order to capture the variation. Methodology of phenomenographic research was adapted for this study. Think aloud and retrospective questioning strategies were used throughout the individually conducted problem solving sessions. The analysis of data showed that thought experiments were frequently used cognitive tools for all level of participants while working on the problems. Four different thought experiment structures were observed which were categorized as limiting case, extreme case, simple case, and familiar case. It was also observed that participants conducted thought experiments for different purposes such as prediction, proof, and explanation. The reasoning resources running behind the thought experiment processes were classified in terms of observed facts, intuitive principles, and scientific concepts. The results of the analysis suggested that, thought experiments used as a creative reasoning instrument for theory formation or hypothesis testing by scientists can also be used by students during the inquiry processes as well as problem solving in instructional settings. It was also argued that, instructional practices can be developed according to the outcomes of thought experiments, which illuminate thinking processes of students and displays hidden or missing components of their reasoning.