Browsing by Issue Date, starting with "1996-10-28"

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劍橋之柳
(1996-10-28)
管管
Enhancement of pool boiling heat transfer in a horizontal water layer through surface roughness and screen coverage
(1996-11-01)
Tsay, JY
;
Yan, YY
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
An experimental investigation was carried out to study the augmentation of heat transfer in saturated pool boiling of a liquid water layer on a heated horizontal stainless steel plate by roughing the surface and/or covering it with a single layer of stainless steel screen. The results were presented in terms of the boiling curves. Effects of various parameters - the surface roughness, liquid level and size of the stainless steel mesh on the boiling heat transfer were examined in detail. The measured data clearly indicated that a lowering of the liquid level from 60 to 5 mm in water depth causes heat transfer reduction. Roughing the surface was found to significantly enhance the heat transfer. Use a layer of metal screen to cover the heated surface was shown to substantially augment the heat transfer especially for a shallow water layer if the mesh size is comparable with the bubble departure diameter. Covering the rough surface with the metal mesh, however, reduced the heat transfer.
Low-temperature and low thermal budget fabrication of polycrystalline silicon thin-film transistors
(1996-11-01)
Lin, HY
;
Chang, CY
;
Lei, TF
;
Liu, FM
;
Yang, WL
A top-gate self-aligned n-channel polycrystalline silicon (poly-Si) thin-film transistor (TFT) has been fabricated with low temperature (less than or equal to 550 degrees C) and low thermal budget process. The ultrahigh vacuum chemical vapor deposition (UHV/CVD) grown poly-Si was served as the channel film, the chemical mechanical polishing (CMP) technique was used to polish the channel surface, plasma-enhanced chemical vapor deposited (PECVD) tetraethylorthosilicate (TEOS) oxide was used as the gate dielectric, and NH3 plasma was used to passive the device. In this process, the solid phase crystallization (SPC) step Is not needed. A field effect mobility of 46 cm(2)/V-s, ON/OFF current ratio of over 10(7), and threshold voltage of 0.8 V are obtained. The significant reduction in process temperature and thermal budget make this process advantageous for larger-area-display peripheral driver circuits on glass substrate.
Characterization of boron silicide layer deposited by ultrahigh-vacuum chemical-vapor deposition
(1996-11-01)
Tseng, HC
;
Pan, FM
;
Chang, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Deposition of a boron-containing layer using B2H6 diluted with H-2 on a Si(001) surface has been carried out in an ultrahigh-vacuum chemical-vapor-deposition (UHV-CVD) system. The deposited boron-containing layers were characterized by atomic force microscope and Auger electron spectroscopy (AES), and the junction depth was determined by secondary-ion-mass spectroscopy. Effective doping is accomplished before perceivable nucleation is initiated. Islands are first formed on the substrate surface at a small dose of diborane, and the grains coalesce to form a rough him for higher doses. At growth temperature above 800 degrees C, the film is composed of possibly SiB6, according to AES depth profiles. Correlation between the junction depth and the sheet resistance of the UHV-CVD-deposited specimens prepared under various conditions is discussed. Postdeposition rapid thermal annealing was performed to study the effect of subsequent thermal cycles on the junction depth and sheet resistance. (C) 1996 American Institute of Physics.
Departure process analysis for earliest-due-date scheduling discipline in ATM switches
(1996-11-01)
Liang, ST
;
Yuang, MC
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
Asynchronous Transfer Mode (ATM) networks are expected to support to diverse mix of traffic sources demanding different Quality Of Service (QOS) guarantees. Regarding the Earliest-Due-Date (EDD) as one of the most promising scheduling disciplines offering delay guarantees in ATM switches, we provided in our previous work a decent queueing analysis for determining the urgency number (D-i) for each service class in an effort to offer 99% delay guarantees for higher delay priority calls under various traffic loads. To further evaluate the end-to-end delay distribution for an observed call, in this paper we present the departure process analysis for the EDD discipline with two urgency numbers D-0 = 0 and D-1 = D associated with two delay-based service classes (class 0 and class 1), respectively. The EDD-based ATM switch is modelled by a discrete-time, single-server queueing system with renewal and non-renewal arrivals. Based on the queueing model, we derive the interdeparture time distribution for the observed traffic stream being multiplexed with other traffic streams. The accuracy of the analysis is confirmed by simulation results. Numerical results demonstrate the characteristic reform of the periodic traffic stream after multiplexing through an EDD-based ATM switch. Since the derived departure process becomes the arrival process of the subsequent ATM switch along the pre-established virtual route, the analysis offers the realization of end-to-end delay computation for ATM networks.
Effect of thin film coating of Au on joint strength in Invar-Invar packages
(1996-11-01)
Wang, SC
;
Wang, CM
;
Wang, C
;
Chang, HL
;
Tu, YK
The effect of a thin film coating of Au on the joint strength, weld width, and penetration depth in laser welding techniques for Invar-Invar packages is investigated experimentally. It is found that the joint strength, weld width, and penetration depth are strongly dependent on the coating of Au thickness on the Invar material. The welded joints with thick Au coating show narrower weld width, shallower penetration, and hence less joint strength than those of the packages with thin Au coating. The increase in both the thermal conductivity and the vapor volume in the welded joints as the coating of Au thickness increases are the possible mechanisms for the reduction. Detailed knowledge of the effect of thin film coatings of Au on the welded materials, which gives both the highest joint strength and good adhesion, is essential for practical design and fabrication of reliable optoelectronic packaging.
Deep levels, electrical and optical characteristics in SnTe-doped GaSb Schottky diodes
(1996-11-01)
Chen, JF
;
Chen, NC
;
Liu, HS
;
交大名義發表
;
電子物理學系
The GaSb layers investigated were grown directly on GaAs substrates by molecular beam epitaxy (MBE) using SnTe source as the n-type dopant. By using admittance spectroscopy, a dominant deep level with the activation energy of 0.23-0.26 eV was observed and its concentration was affected by the Sb-4/Ga flux ratio in the MBE growth. A lowest deep-level concentration together with a highest mobility was obtained for GaSb grown at 550 degrees C under a Sb-4/Ga beam equivalent pressure (BEP) ratio around 7, which should correspond to the lowest ratio to maintain a Sb-stabilized surface reconstruction. In the Hall measurement, an analysis of the temperature-dependent mobility shows that the ionized impurity concentration increases proportionally with the sample's donor concentration, suggesting that the ionized impurity was introduced by an SnTe source. In addition, optical properties of an undoped p-, a lightly and heavily SnTe-doped GaSb layers were studied by comparing their photoluminesence spectra at 4.5K.
A queue manager chip for shared buffer ATM switches
(1996-11-01)
Lin, YS
;
Huang, HC
;
Shung, CB
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents an efficient queue manager chip for controlling a 16 x 16 shared buffer ATM switch with a 256-cell buffer. Compared to conventional implementations of queue managers for shared buffer ATM switches, our design eliminates the idle address FIFO and the pre-allocated bubbles at the tails of output queues. The former reduces the storage size required for queue management, while the latter improves the effective buffer capacity. Such modular implementation also provides flexibilities in queue management implementation. Backpressure with soft-full and hard-full flow control for multi-stage expansion and two priority classes with push-out cell discarding are supported without extra hardware overhead. This chip was designed and fabricated using 0.8 mu m CMOS technology. It has 35,700 transistors in a chip area of 28.3 mm(2), with a core of 10.4 mm(2) and 31,960 transistors. Two test sequences were developed during the design phase to fully verify the queue management functions of the prototype chip. The queue manager chip was tested up to 36 MHz, and is able to control a 16 x 16 shared buffer switch with a 155 MHz link rate.
Fuzzy adaptive control of machining processes with a self-learning algorithm
(1996-11-01)
Hsu, PL
;
Fann, WR
;
電控工程研究所
;
Institute of Electrical and Control Engineering
When machining conditions change significantly, applying parameter-adaptive control to the cutting system by varying the table feedrate allows a constant cutting force to be maintained Although several controller schemes have been proposed, their cutting control performance is limited especially when the cutting conditions vary significantly. This paper presents an adaptive fuzzy logic control (FLC) developed for cutting processes under various cutting conditions, The controller adopts opt-line scaling factors for cases with varied cutting parameters. In addition, a reliable self-learning (SL) algorithm is proposed to achieve even better cutting performance by modifying the adaptive FLC rule base according to properly weighted performance measurements. Both simulation and experimental results show that given a sufficient number of learning cases, the adaptive SL-FLC is effective for a wide range of applications. The successful implementation of the proposed adaptive SL-FLC algorithm on an industrial heavy-duty machining center indicates that the proposed adaptive SL-FLC is feasible for use in manufacturing industries.
Biodegradation of hydrogen sulfide by a laboratory-scale immobilized Pseudomonas putida CH11 biofilter
(1996-11-01)
Chung, YC
;
Huang, CP
;
Tseng, CP
;
環境工程研究所
;
生物科技學系
A heterotrophic Pseudomonas putida CH11 was isolated from livestock farming wastewater and applied for the treatment of H2S-containing gas. Extensive tests including removal characteristics, metabolic products, and removal efficiencies of H2S by P. putida CH11 were examined in batch and continuous systems. The optimum pH required to remove hydrogen sulfide was found in the range of 6-8. The maximum removal rate and the saturation constant were calculated to be V-m=1.36 g S/day . kg dry bead and K-s=45.9 ppm, respectively. The main metabolic product of H2S oxidation was determined to be elemental sulfur. When P. putida CH11 was immobilized within Ca alginate, the cells exhibited high H2S removal efficiency, in excess of 96%, at concentrations of hydrogen sulfide from 10 to 150 ppm (now rates of 36 and 72 L/h). These results suggest that P. putida CH11 immobilized within Ca alginate has the potential to be used as a H2S removal agent.
An object model at conceptual level to support updatable views on object-oriented databases
(1996-11-01)
Pan, WW
;
Yang, WP
;
資訊工程學系
;
Department of Computer Science
The research on view mechanisms for object-oriented databases can be classified into two independent issues, languages to define views and the underlying object models. This paper presents an object model at the conceptual level of abstraction. We call it the view class and real-world object model (V-R model). The major goal of the V-R model is intended to support updatable views efficiently for the object-oriented database systems. The V-R model elaborates a special method to describe the instance-of relationship between stored objects and classes so that a stored object can be the instance of several classes simultaneously. Query results and views can be managed like classes without creating temporary objects or tuples since the V-R model is closed against query operations. In this way, updates on views can be supported easily. This paper also explores the update semantics in depth. By utilizing the specialty of the V-R model, a more eligible update translation is proposed for the updates on classes with or without inheritance relationships and for the updates on views. To show that the V-R model is not only theoretical, how to implement the V-R model and how to integrate the V-R model into an object-oriented database system are illustrated. (C) Elsevier Science Inc. 1996
Low-temperature and low thermal budget fabrication of polycrystalline silicon thin-film transistors
(1996-11-01)
Lin, HY
;
Chang, CY
;
Lei, TF
;
Liu, FM
;
Yang, WL
A top-gate self-aligned n-channel polycrystalline silicon (poly-Si) thin-film transistor (TFT) has been fabricated with low temperature (less than or equal to 550 degrees C) and low thermal budget process. The ultrahigh vacuum chemical vapor deposition (UHV/CVD) grown poly-Si was served as the channel film, the chemical mechanical polishing (CMP) technique was used to polish the channel surface, plasma-enhanced chemical vapor deposited (PECVD) tetraethylorthosilicate (TEOS) oxide was used as the gate dielectric, and NH3 plasma was used to passive the device. In this process, the solid phase crystallization (SPC) step Is not needed. A field effect mobility of 46 cm(2)/V-s, ON/OFF current ratio of over 10(7), and threshold voltage of 0.8 V are obtained. The significant reduction in process temperature and thermal budget make this process advantageous for larger-area-display peripheral driver circuits on glass substrate.
A reassembly strategy for reducing IN/PCS signalling traffic
(1996-11-01)
Wu, KR
;
Jan, RH
;
資訊工程學系
;
Department of Computer Science
This paper proposes a simple assembly/disassembly part (ADP) for the signalling system no. 7 (SS7) protocol to reduce the signalling traffic loads in intelligent networks (IN) and personal communication service (PCS) networks. The ADP combines two or more messages with the same destinations into a single message, thereby reducing signalling traffic without affecting SS7 protocol operations, The numerical results show that the proposed method can reduce traffic among signalling points 9 similar to 17%.
Current distribution and vortex-vortex interaction in a superconducting film of finite thickness
(1996-11-01)
Wei, JC
;
Yang, TJ
;
電子物理學系
;
光電工程學系
;
Department of Electrophysics
The current distribution due to a single vortex in a superconducting film of finite thickness is calculated, based on the London model. At large distances from the vortex core, the current density on the surface of the superconductor was found to follow the 1/r(2) law which has a simple expression, J(s)(r, 0) approximate to phi(0)[coth(d/lambda) + csch (d/lambda)]/2 pi mu(0) lambda r(2). We also find that the interaction energy between two vortices has the form, U-int(r/(12)) phi(0)(2)[H-0(r(12)/lambda') - Y-0(r(12)/lambda l)], when the film is not too thick and at large distances between two vortices. This potential differs from Pearl's result by the new effective penetration depth lambda' = 2 lambda coth (d/lambda).
PPD: A practical parallel loop detector for parallelizing compilers on multiprocessor systems
(1996-11-01)
Yang, CT
;
Wu, CT
;
Tseng, SS
;
交大名義發表
;
資訊工程學系
It is well known that extracting parallel loops plays a significant role in designing parallelizing compilers. The execution efficiency of a loop is enhanced when the loop can be executed in parallel or partial parallel, like a DOALL or DOACROSS loop. This paper reports on the practical parallelism detector (PPD) that is implemented in PFPC (a portable FORTRAN parallelizing compiler running on OSF/1) at NCTU to concentrate on finding the parallelism available in loops. The PPD can extract the potential DOALL and DOACROSS loops in a program by invoking a combination of the ZIV test and the I test for verifying array subscripts. Furthermore, if DOACROSS loops are available, an optimization of synchronization statement is made. Experimental results show that PPD is more reliable and accurate than previous approaches.
An efficient nearest neighbor searching algorithm with application to LBG codebook gene ration
(1996-11-01)
Wu, KS
;
Lin, JC
;
資訊工程學系
;
Department of Computer Science
The nearest neighbor (NN) searching problem has wide applications. In vector quantization (VQ), both the codebook generation phase and encoding phase (using the codebook just generated) often need to use the NN search. Improper design of the searching algorithm will make the complexity quite big as vector dimensionality k or codebook size N increases. In this paper, a fast NN searching method is proposed, which can then accelerate the LEG codebook generation process for VQ design. The method successfully modifies and improves the LAESA method. Unlike LAESA, the proposed k/2 ''fixed'' points (allocated far from the data) and the origin are used as the k/2+1 reference points to reduce the searching area. The overhead in memory is only linearly proportional to N and k. The time complexity, including the overhead, is of order O(kN). According to our experiments, the proposed algorithm can reduce the time burden while the distortion remains identical to that of the full search.
A Xerion-based Perl program to train a neural network for grid pattern recognition
(1996-11-01)
Kao, JJ
;
交大名義發表
;
環境工程研究所
;
National Chiao Tung University
;
Institute of Environmental Engineering
Neural network training with the back propagation algorithm is an important artificial intelligence technique for grid pattern recognition. The training is time-consuming however and generally requires a trial-and-error procedure to configure the network. A Perl program executed with Xerion is presented to relieve the;training burden. Statistical reports such as computation time, learning performance, and validation performance are generated automatically by the program. A case study applying the program for training networks to determine a drainage pattern from Digital Elevation Model data is demonstrated and discussed. Manually determining drainage patterns from topographical maps for a grid-based model is tedious and subjective. The neural network has a self-learning capability that can replace human judgment involved in the conventional approach. Copyright (C) 1996 Elsevier Science Ltd.
Dynamic output feedback control of nonlinear singularly perturbed systems
(1996-11-01)
Pan, ST
;
Hsiao, FH
;
Teng, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, the stabilization problem of two classes of nonlinear singularly perturbed systems via dynamic output feedback is investigated. First, we consider the nonlinear singularly perturbed systems in which the nonlinearities are continuously differentiable. The theoretical result demonstrates that, using the factorization approach, the dynamic output feedback controller designed for the reduced-order model of the linearized system is a stabilizing compensator for the original nonlinear singularly perturbed system, provided that epsilon is sufficiently small. Second, the nonlinear singularly perturbed systems in which the nonlinearities are not necessarily continuously differentiable but satisfy the global Lipschtz condition are examined. Combining the dynamic output feedback controller that stabilizes the reduced-order model of the linear part of the nonlinear singularly perturbed system with the quasi-stability result of Persidskii, a two-step compensating scheme is proposed to stabilize the original nonlinear singularly perturbed system under consideration fora sufficiently small epsilon. Copyright (C) 1996 Published by Elsevier Science Ltd
Experimental observation and conjugated heat transfer analysis of vortex flow development in mixed convection of air in a horizontal rectangular duct
(1996-11-01)
Lin, WL
;
Ker, YT
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
A combined flow visualization and conjugated heat transfer analysis was carried out to study the axial evolution of the buoyancy induced secondary vortex flow in a mixed convective air flow through a bottom heated horizontal rectangular duct. In the experiment the cross plane secondary flow was visualized at selected cross-sections. While in the conjugated analysis, the unsteady three-dimensional Navier-Stokes and energy equations for the flow were coupled with the unsteady two-dimensional conduction equations for the solid walls and were solved together numerically. Results were obtained for the Reynolds number ranging from 35 to 102 and Grashof number from 1600 to 5.8 x 10(5), covering the steady and time periodic flows. Both the experimental and numerical results clearly showed the generation of the longitudinal vortex rolls in the entry half of the duct and the merge of these rolls downstream. At higher buoyancy-to-inertia ratio more rolls were generated and they merged into fewer and larger rolls. Significant conjugated heat transfer effects were noted from the numerical results. Copyright (C) 1996 Elsevier Science Ltd.
Fuzzy adaptive control of machining processes with a self-learning algorithm
(1996-11-01)
Hsu, PL
;
Fann, WR
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
When machining conditions change significantly, applying parameter-adaptive control to the cutting system by varying the table feedrate allows a constant cutting force to be maintained Although several controller schemes have been proposed, their cutting control performance is limited especially when the cutting conditions vary significantly. This paper presents an adaptive fuzzy logic control (FLC) developed for cutting processes under various cutting conditions, The controller adopts opt-line scaling factors for cases with varied cutting parameters. In addition, a reliable self-learning (SL) algorithm is proposed to achieve even better cutting performance by modifying the adaptive FLC rule base according to properly weighted performance measurements. Both simulation and experimental results show that given a sufficient number of learning cases, the adaptive SL-FLC is effective for a wide range of applications. The successful implementation of the proposed adaptive SL-FLC algorithm on an industrial heavy-duty machining center indicates that the proposed adaptive SL-FLC is feasible for use in manufacturing industries.