Browsing by Author "Tseng, CH"

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A convenient solver for solving optimal control problems
(2005-07-01)
Huang, CH
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Tseng, CH
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機械工程學系
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Department of Mechanical Engineering
This paper focuses on the development of a solver for solving optimal control problems. A developed numerical optimal control module integrated with the Sequential Quadratic Programming method is introduced. An optimal control problem solver based on the proposed method is implemented to solve optimal control problems efficiently in engineering applications. In addition, a systematic procedure for solving optimal control problems by using the optimal control problem solver is also proposed. A time-optimal benchmark problem presented in the literature is used to illustrate for the capability and facility of solving optimal control problems. The numerical results demonstrate the proposed method and the procedure suggested in this paper are helpful to engineers in solving optimal control problems in a systematic and efficient manner.
A method for improved bicycle shifting performance
(1997)
Wang, CC
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Tseng, CH
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Fong, ZH
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交大名義發表
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機械工程學系
The overwhelming majority of bicycles, the most common human-powered vehicles (HPVs), are equipped with sophisticated derailleur systems that serve the same purpose as transmissions in motor vehicles: enabling more efficient use of input power through selection of suitable gear reduction ratios. This paper presents a method for improving the performance of bicycle derailleur systems by modifying sprocket shape to eliminate jerkiness, slippage and rattling noise, and guide chain movement from one gear to another mole quickly and directly. The sprocket modification CAD/CAM program, and an integrated optimization tool, were developed on an IRIS INDIGO/4000 workstation.
A new high-order non-uniform Timoshenko beam finite element on variable two-parameter foundations for vibration analysis
(1996-03-21)
Hou, YC
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Tseng, CH
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Ling, SF
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機械工程學系
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Department of Mechanical Engineering
A new finite element model of a Timoshenko beam is developed to analyze the small amplitude, free vibrations of non-uniform beams on variable two-parameter foundations. An important characteristic of the model is that the cross-sectional area, the second moment of area, the Winkler foundation modulus and the shear foundation modulus are all assumed to vary in polynomial forms, implying that the beam element can deal with commonly seen non-uniform beams having different cross-sections such as rectangular, circular, tubular and even complex thin-walled sections as well as the foundation of beams which vary in a general way. Thus this new beam element model enables users to handle vibration analysis of more general beam-like structures. In this paper, by using cubic polynomial expressions for the total deflection and the bending slope of the beam, the mass and stiffness matrices of the element are derived from energy expressions. The element model can accommodate various boundary conditions to represent a Timoshenko beam accurately. Excellent agreement with other investigators' results and a rapid rate of convergence with relatively few elements are demonstrated. This study also brings out the fact that the complicated form of this new beam model is necessary because of its advantage over linear or uniform approximations of the non-uniform foundation and/or geometrical properties of beams. The same accuracy being achieved with fewer elements is the main advantage. Finally, an optimum design problem is illustrated to emphasize the practical application of this element. (C) 1996 Academic Press Limited
A novel germanium doping method for fabrication of high-performance p-channel poly-Si1-xGex TFT by excimer laser crystallization
(2003-04-01)
Chang, TK
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Chu, FT
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Lin, CW
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Tseng, CH
;
Cheng, HC
In this letter, a novel process for fabricating p-channel poly-Si1-xGex thin-film transistors (TFTs) with high-hole mobility was demonstrated. Germanium (Ge) atoms were incorporated into poly-Si by excimer laser irradiation of a-Si1-xGex/poly-Si double layer. For small size TFTs, especially when channel width/length (W/L) was less than 2 mum/2 mum, the hole mobility of poly-Si1-xGex TFTs was superior to that of poly-Si TFTs. It was inferred that the degree of mobility enhancement by Ge incorporation was beyond that of mobility degradation by defect trap generation when TFT size was shrunk to 2 mum/2 mum. The poly-Si0.91Ge0.09 TFT exhibited a high-hole mobility of 112 cm(2)/V-s, while the hole mobility of the poly-Si counterpart was 73 cm(2)/V-s.
A novel laser-processed self-aligned gate-overlapped LDD poly-Si TFT
(2002-03-01)
Lin, CW
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Tseng, CH
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Chang, TK
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Lin, CW
;
Wang, WT
A novel process for fabricating self-aligned gate-overlapped LDD (SAGOLDD) poly-Si thin film transistors (TFTs) was demonstrated. Laser Irradiation for dopant activation was performed from the backside of the quartz wafer. The graded LDD structure was naturally formed under the gate edges due to the lateral diffusion of the dapants during the laser activation. In comparison with the conventional laser-processed self-aligned poly-Si TFTs, the SAGOLDD poly-Si TFTs exhibited lower leakage current, suppressed kink effect, and higher reliability. Moreover, the proposed process was simple and very suitable for low-temperature process.
A study on the bearing contact of roller gear cams
(2001)
Lo, JS
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Tseng, CH
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Tsay, CB
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機械工程學系
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Department of Mechanical Engineering
This study presents contact ellipse characteristics of the roller gear cams consisting of cambered rollers and screw cam surfaces. Principal curvatures and directions of generated cam surfaces are studied. The dimensions and the directions of contact ellipses are also evaluated. The investigation results are most helpful to understand contact nature, and contact stresses of the roller gear cam, which may be considered as design indices for performance consideration. (C) 2001 Elsevier Science B.V. All rights reserved.
A study on the Hertzian stress of the roller gear cam
(2000)
Lo, JS
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Tseng, CH
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Tsay, CB
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機械工程學系
;
Department of Mechanical Engineering
This study presented the characteristics of Hertzian stress of roller gear cams that are composed of a cambered roller and a screwed 3D, cam surface. Based on the principal curvatures and directions of the generated cam surfaces and its cambered mating followers, pressure angle and contact force, the contact ellipses were derived. The investigated results are most helpful to the understanding of the contact nature and the contact stress of the roller gear cam which may be considered as design indices for further design consideration.
A theoretical investigation ofthe resonance damping performance of magnetic material coating in Power/Ground plane structures
(2005-11-01)
Wu, LK
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Tseng, CH
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傳播研究所
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Institute of Communication Studies
Power bus structure, consisting of two parallel solid power and ground planes separated by an insulator, behaves as a cavity resonator at high frequencies. Noise on the power bus, due to a sudden change in the current drawn by an active component, can appear as an undesired spatial fluctuation in the voltage between power and ground, especially at resonant frequencies of the resultant cavity, which may lead to problems in signal integrity, excessive delays, false switching, and radiated emission. These resonances can be suppressed by introducing high-frequency loss into the structure. This paper investigates a simple method to reduce self-/transfer impedance of power/ground planes for mitigating power/ground bounce in high-speed printed circuit board design by adding a thin layer of magnetic material coating to the inside-facing surfaces of copper power and ground plates to increase their effective high-frequency surface impedance. The increased surface impedance will increase the attenuation constant of the propagating wave inside the cavity that benefits reduction of cavity's quality factor (Q factor). The simulation results obtained from a modified cavity resonator model show that increasing surface impedance can dramatically reduce self- and transfer impedances at board resonant frequencies.
An automatic gearshift logic for discrete bicycle transmissions
(2003)
Chien, HC
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Tseng, CH
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機械工程學系
;
Department of Mechanical Engineering
Considering the characteristics of a discrete transmission on bicycles, this study proposes an automatic gearshift logic for discrete bicycle transmissions. This logic calculates shifting occasions of a transmission for the individual. Shifting gears at these shifting occasions can keep the individual pedaling in the suitable cadence region, namely satisfy his/her ergonomic necessity.
An automatic transmission for bicycles: a simulation
(2004-02-01)
Chien, HC
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Tseng, CH
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機械工程學系
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Department of Mechanical Engineering
A new design of an automatic transmission for bicycles was simulated. A sensitivity analysis found most environmental and bicycle variables had little effect but cycling velocity was very important while pedal rpm and gradient of the ground had some effect. The new design transmission therefore emphasizes velocity, pedal rpm and gradient of the ground when selecting the optimum gear ratios. Since the comfortable pedal rpm differs from cyclist to cyclist, this new automatic transmission continuously measures the pedal rpm and calculates an average to efficiently learn the cycling habit of different cyclists.
An efficient optimum design procedure for bicycle rear derailleurs
(1996)
Hou, YC
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Su, SH
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Tseng, CH
;
Fong, ZH
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交大名義發表
The rear derailleur on a multi-speed bicycle guides the running chain rapidly and precisely to a selected freewheel sprocket position without disengagement from the freewheel assembly. Therefore, the design of rear derailleurs is most important for designers. An efficient optimum design procedure for rear derailleurs is presented in this paper. Based on an established mathematical model, a series of optimum design sub-problems derived from the original optimum design problem are formulated and solved to meet all design requirements. The advantage of dividing the original design problem into several sub-problems is that it makes the upper/lower bounds of design variables in each sub-problem easier to determine. This reduces the trial-and-error efforts during iterative searching for optimum solutions. Thus, the design procedure becomes more rapid and efficient. It is worth emphasizing that the design procedure proposed herein is applicable to most known types of rear derailleurs.
An experimental approach characterizing rear bicycle derailleur systems part I: Performance test
(1998)
Lin, TY
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Tseng, CH
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機械工程學系
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Department of Mechanical Engineering
The derailleur system on a bicycle serves the same purpose as transmissions in motor vehicles: they provide different speed ratios for different situations. Cyclists can choose between speed and labour-saving by moving shift levers to complete a series of mechanical motions that change gears. Therefore, the shifting performance of the derailleur system is very important in designing derailleur system components. This paper proposes a systematic procedure for arranging the design steps for the derailleur system. It promises that the derailleur system components will integrate well and operate effectively. The performance test indices in the present paper can be used to judge the shifting performance during the period of shifting gears. Many design and manufacturing imperfections in products can also be found using the experimental results from performance test. Experimental procedures provide an environment that replaces subjective human 'feel' tests used in the past.
An experimental approach characterizing rear bicycle derailleur systems part II: the stability region and its applications
(1998)
Lin, TY
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Tseng, CH
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Fong, ZH
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機械工程學系
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Department of Mechanical Engineering
An important concept in the design procedure of bicycle derailleur systems called the stability region is presented in this study. The stability region properties are introduced, and experimental procedures for stability region determination are proposed. The stability ratio, which is a performance index for the stability region is also defined. Shift-lever characteristics such as indexed point, over-shifting and under-shifting can be determined from the stability region experiments. Design concepts and skills for shift lever design are proposed, and a case study is given for demonstration.
An innovative piston retractor for bicycle hydraulic disc braking systems
(2004-03-01)
Mao, YJ
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Tseng, CH
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機械工程學系
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Department of Mechanical Engineering
Hydraulic disc brake systems offer various advantages over other braking systems, including a good heat dissipation rate, a high force enlargement ratio and a constant braking force in various environments. However, they have an important defect as the lining pads remain at a small clearance from the disc rotor, occasionally producing judder, noise and power loss when freely running. This study proposes an innovative piston retractor by utilizing the theory of innovative problem solving. The prototype is manufactured and installed in a commercial brake caliper. Experimental results are obtained and demonstrate the feasibility of applying the proposed design in a bicycle hydraulic disc braking system. Retraction performance of the proposed design is superior to a current product with a ring seal as its retractor and another product with a retractor that does not contain an automatic adjustment mechanism. The clearance between the lining pad and disc rotor is successfully kept at a larger value than these products regardless of the pad wear.
An investigation of bias temperature instability in hydrogenated low-temperature polycrystalline silicon thin film transistors
(2002-09-01)
Lin, CW
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Tseng, CH
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Chang, TK
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Chang, YH
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Chu, FT
The instability mechanisms of the hydrogenated n-channel low-temperature polycrystalline silicon thin film transistors under on-state stress were investigated with various bias stress conditions and device channel widths. It was found that hot carrier degradation which originated from a high drain electric field and self-heating during high current operation were the two dominant mechanisms responsible for device degradation. An electrically reversible depassivation/passivation phenomenon was also found in devices under high current stress. but not in those under hot carrier stress. It was inferred that the self-heating effect would accelerate the bond breakage and diffusion of hydrogen ions, thus enhancing the rate of depassivation/passivation. Moreover. when the Current in the hot carrier stress mode was sufficiently high. self-heating became the dominant degradation mechanism and hot carrier degradation phenomenon was also suppressed for devices with large channel width, Meanwhile, the electrically reversible depassivation/passivation phenomenon also occurred in this case.
Bearing contact analysis of the involute spur planetary gear train
(2001)
Chen, JL
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Tseng, CH
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Tsay, CB
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機械工程學系
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Department of Mechanical Engineering
The goal of this study is to determine the dimensions and orientations of instant contact ellipses of gear surfaces in the meshing of the planetary gear train in order to recommend the proper amount of the crowning radii. The mathematical model for the surface profiles of the simple planetary gear train with the crowned planet gear is developed to simulate gear-meshing conditions and obtain the contact points. Principal curvatures and directions of the planetary gear train are derived and investigated based on the theory of gearing. The dimensions and orientations of the contact ellipses of the planetary gear train due to the assembly errors of different kinds of axial misalignments in different crowning radii can further be developed from the principal curvatures and directions of gear surfaces. Examples are presented to illustrate the above-mentioned investigations.
Creative mechanism design for a prosthetic hand
(2004-11-01)
Chang, WT
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Tseng, CH
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Wu, LL
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機械工程學系
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Department of Mechanical Engineering
In this paper, an auxiliary methodology called the creative mechanism design is introduced into the innovation of gripping devices for prosthetic hands. This methodology is a systematic approach based on modification of existing devices for the generation of all possible topological structures of mechanisms and mechanical devices. An existing gripping device (Teh Lin ATG-5F prosthetic hand) constructed by a planar six-bar linkage with one degree of freedom is dealt with by using this methodology. Through the processes of generalization, number synthesis, specialization and particularization for the existing design, five new mechanisms are created in this study to apply to anthropomorphic prosthetic hands. The results show that the methodology for creative mechanism design is a powerful tool for creating new categories of mechanisms to avoid existing designs that have patent protection and can help designers in the conceptual phase. Also, this methodology is validated as a useful way to improve prosthetic hands for amputees.
Design considerations for assembly in planetary gear trains
(2000)
Chen, JL
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Tseng, CH
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機械工程學系
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Department of Mechanical Engineering
Relative phase angles between planetary gears in the multi-stage planetary gear trains are the important design consideration for assembling. Different gear sizes require different relative phase angles. This study investigated the design considerations for planetary gear trains for assembling, especially for planetary gear sets. Two methods for determining the relative phase angles for single-stage and multiple-stage planetary gear trains with evenly spaced planetary gears are proposed. Numerical examples are used to demonstrate these methods.
Effect of temperature and illumination on the instability of a-Si : H thin-film transistors under AC gate bias stress
(2001-04-01)
Huang, CY
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Teng, TH
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Yang, CJ
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Tseng, CH
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Cheng, HC
This work investigates the temperature and illumination effects on the a-SM thin-film transistors (a-SiH TFTs) under AC gate bias stress to find the larger threshold voltage shift and subthreshold swing change for the bias-temperature-stress (BTS) and bias-illumination-stress (BIS). Excess carriers from thermal-generation electron-hole pairs or photoexcited electron-hole pairs may significantly influence the instability of a-SM TFTs during bias stress. The instability mechanisms originate from the carrier-induced defect Creation enhanced by thermal generation in the BTS case and also emphasized by photoexcitation for the BIS case. Both stress conditions will induce a larger threshold voltage shift and higher cutoff frequency than those for simple bias stresses.
Effects of excimer laser dopant activation on low temperature polysilicon thin-film transistors with lightly doped drains
(2001-11-01)
Tseng, CH
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Lin, CW
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Chang, TK
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Cheng, HC
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Chin, A
Excimer laser annealing has been utilized to manufacture low temperature polycrystalline silicon thin-film transistors with lightly doped drain (LDD) structures. The excimer laser annealing can effectively reduce the thermal budget of source/drain dopant activation, namely, without substrate heating. With the advantages of LDD structure, high performance device characteristics with a low "off" state current of 4.38 x 10(-12) A/mum, high on/off current ratio of 1.6 x 10(7). and good field-effect mobility of 268 cm(2)/V s. can be achieved simultaneously. (C) 2001 The Electrochemical Society.