Synthetic gas, syngas, is a popular alternative fuel for the gas turbine industry, but the composition of syngas can contain different types and amounts of contaminants, such as carbon dioxide, methane, moisture, and nitrogen, depending on the industrial process involved in its manufacturing. The presence of steam in syngas blends is of particular interest from a thermo-chemical perspective as there is limited information available in the literature. This study investigates the effect of moisture content (0 ? 15% by volume), temperature (323 ? 423 K), and pressure (1 ? 10 atm) on syngas mixtures by measuring the laminar flame speed in a newly developed constant-volume, heated experimental facility. This heated vessel also broadens the experimental field of study in the authors? laboratory to low vapor pressure fuels and other vaporized liquids. The new facility is capable of performing flame speed experiments at an initial pressure as high as 30 atm and an initial temperature up to 600 K. Several validation experiments were performed to demonstrate the complete functionality of the flame speed facility. Additionally, a design-of-experiments methodology was used to study the mentioned syngas conditions that are relevant to the gas turbine industry. The design-of-experiments methodology provided the capability to identify the most influential factor on the laminar flame speed of the conditions studied. The experimental flame speed data are compared to the most up-to-date C4 mechanism developed through collaboration between Texas A&M and the National University of Ireland Galway. Along with good model agreement shown with all presented data, a rigorous uncertainty analysis of the flame speed has been performed showing an extensive range of values from 4.0 cm/s to 16.7 cm/s. The amount of carbon monoxide dilution in the fuel was shown to be the most influential factor on the laminar flame speed from fuel lean to fuel rich. This is verified by comparing the laminar flame speed of the atmospheric mixtures. Also, the measured Markstein lengths of the atmospheric mixtures are compared and do not demonstrate a strong impact from any one factor but the ratio of hydrogen and carbon monoxide plays a key role. Mixtures with high levels of CO appear to stabilize the flame structure of thermal-diffusive instability. The increase of steam dilution has only a small effect on the laminar flame speed of high-CO mixtures, while more hydrogen-dominated mixtures demonstrate a much larger and negative effect of increasing water content on the laminar flame speed.

A multi-speed drive hub is one of important components in transmission system. The purpose of this work is to develop a system methodology for the design of multi-speed bicycle drive hubs. First, analyse multi-speed drive hub patents to identify the basic characteristics and design requirement of multi-speed drive hub. Second, using a systematized mathod to synthesize the feasible gear trains. Third, a method is proposed to determine the feasible multi-speed sequence tables for each gear train. Fourth, an analytic method is formulated to synthesize the gear ratios and gear teeth according to a set of desired speed ratios. Fifth, design and dispose governors of multi-speed drive hubs. The results of this work will be benefit to the development and design of multi-speed bicycle drive hubs.

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Adjustable-speed drives (ASDs) are often used in commercial and industrial facilities to improve process control and save energy. However, ASDs are the sensitive load equipment as regards to voltage sag. During the sag, the dc-bus capacitor of a typical ASD will discharge depending on the loading condition. The voltage of the dc bus decreases and could lead to a trip of the device. In order to understand the voltage sag tolerance capability of ASDs. Based on IEC 61800-3 and IEC 61000-4-11, this research presents the test results of ASD subjected to voltage sags under different operating conditions. The tests focus on different types of voltage sags, operating situations and designs of ASDs.

The objective of this thesis is to provide the systematic design procedure for a high-speed PM motor with portable sizes, along with the detailed mathematical model developments and the thorough operational analysis. The entire scheme is realized by first following an available design reference to estimate the desired machine physical structures. Then, based on the related field theory, recoil line characteristics of permanent magnets, and the magnetic equivalent circuit method, the system mathematical model can be devised. Finally, the system operational behaviors can be investigated by the devised analytical models, and their accuracies will also be confirmed by the reference design tool. It is believed that the proposed design and verification scheme can provide a valuable and reasonable guidance for the related industry application.

The wheelchair is an auxiliary tool for people who have defective legs. In comparison with the power wheelchair, the manual wheelchair has the advantage of low price and easy carrying. The regular, standard manual wheelchair is only suitable for residential environment and short-distance movement, and it¡¦s unsuitable for outdoor recreation and long-distance movement. The purpose of this study is to develop the manual wheelchair for outdoor recreation and long-distance movement, so that the users can expand their living space beyond the residential areas. In order to enhance the efficiency of propulsion for manual wheelchairs, a systematic designing method for propulsive mechanisms is proposed in this study in which the propulsive way of the traditional manual wheelchair is replaced by propelling the propulsive mechanism. In order to let the wheelchair be adapted to all kinds of environments, the multi-speed drive hub is applied to the manual wheelchair to enhance the users¡¦ force with more flexibility. In addition, this study also designs and manufactures a wheelchair to test the functions. The results of the test are then recorded and examined to provide the references for the future design.

­^¤åºK­n A multi-speed drive hub is one of important components in transmission system. The purpose of this work is to develop a system methodology for the design of multi-speed bicycle drive hubs by using a concept of combination. First, identify the basic characteristics and design requirement of combinative multi-speed drive hub. Second, using three combinative the useful gear trains. Third, a method is proposed to determine the feasible multi-speed sequence tables for each gear train. Fourth, an analytic method is formulated to synthesize the gear ratios and gear teeth according to a set of desired speed ratios. Fifth, a computer programs developed for the automatic analysis the transmission performance of drive hubs. The results of this work will be benefit to the development and design of multi-speed bicycle drive hubs.

The high speed machining is now recognized as one of the key manufacturing technologies. It possesses several better characteristics than those of a conventional machining way. For example, low chip load, and low cutting-heat generation can be obtained. It also contributes to high productivity and throughput. In this thesis, the technique about the high speed machining for cutting the aluminum thin-walled components will be discussed. An audio signal measuring system will be established to measure sound pressure for avoiding chatter. Meanwhile, the tool path will also be revealed in this thesis.

Abstract In this thesis, the variation of the natural frequencies of a drill during the high speed drilling processes has been investigated. The Pro-E and MARC finite element packages were used to formulate the twisted drills. Two numerical methods,i.e. Lanczos and Inverse Power Sweep, have been employed to solve the corresponding eigen value problems.The effects of following parameters,e.g. drilling speed,axial load and drilling conditions on the natural frequencies of a drill was simulated numerically and measured experimentally. Four springs with different spring stiffness attached on the drill tip is used to simulate the drill as it penetrated into the workpiece. The variation of the drilling responses under different drilling speeds have been measured. Results indicate the measured results agree very well with the measured data.Frequency spectrum distributions indicate the drilling frequency and the twice drilling frequency are the key response frequency of the axial thrust force, and the drill of frequencyisthe only key frequency which dominates the torque response.Experimental results also show the thrust forces estimated from the empirical equation have good correlation with these measured data.

A multi-speed drive hub is one of important components in transmission system. The purpose of this work is to develop a system methodology for the design of multi-speed bicycle drive hubs. First, identify the basic characteristics and design requirement of multi-speed drive hub. Second, using the useful gear trains. Third, a method is proposed to determine the feasible multi-speed sequence tables for each gear train. Fourth, an analytic method is formulated to synthesize the gear ratios and gear teeth according to a set of desired speed ratios. Fifth, the basic theory for transmission analysis of multi-speed drive hubs will be developed. The results of this work will be benefit to the development and design of multi-speed bicycle drive hubs.