Browsing by Issue Date, starting with "1997-12-01"

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Curing behaviour of compatible interpenetrating polymer networks based on epoxy and methacrylated epoxy
(1997-12-01)
Wang, MW
;
Lee, CT
;
Lin, MS
;
應用化學系
;
Department of Applied Chemistry
Compatible interpenetrating polymer networks (IPNs) based on diglycidyl ether of bisphenol A (DGEBA) and methacrylated diglycidyl ether of bisphenol A (MADGEBA) in weight ratios of 100/0, 75/25, 50/50, 25/75 and 0/100 were blended and cured simultaneously by using dicumyl peroxide (DICUP) and hexahydrophthalic anhydride (HHPA) as curing agents. Fourier transform infrared spectroscopy (FTIR) was employed to investigate the intermolecular interactions and functional group changes. Viscosity increases during crosslinking were examined with a Brookfield viscometer. Curing exothermic peaks were studied with differential scanning calorimetry (DSC). The gel fractions of various IPN compositions were measured with a Soxhlet extractor. Samples thus prepared were checked for their compatibility by measuring glass transitions with DSC and damping peaks with rheometric dynamic spectroscopy (RDS). Experimental results revealed that good compatibility between components induced a network interlock, which subsequently resulted in incomplete cure of the IPN materials.
Enhancement of anaerobic digestion of waste activated sludge by alkaline solubilization
(1997-12-01)
Lin, JG
;
Chang, CN
;
Chang, SC
;
環境工程研究所
;
Institute of Environmental Engineering
The performance of an anaerobic digestion fed with waste activated sludge (WAS) pretreated with NaOH was examined The sludge was periodically collected from a municipal wastewater-treatment plant. The laboratory work was run in four I-I semi-continuous anaerobic digestion reactors. Reactor-A was fed with untreated WAS at 1% total solids (TS). The other three reactors, B, C and D, were respectively fed with WAS (1% TS) pretreated with 20 meq/l NaOH, WAS (1% TS) pretreated with 40 meq/l NaOH, and WAS (2% TS) pretreated with 20 meq/l NaOH. The reactors were operated at 35 degrees C at four hydraulic retention rimes - 20, 13, 10 and 7.5 days. The performances of reactors B, C and D, in terms of chemical oxygen demand (GOD), volatile solids (VS) removal, and gas production, were superior to that of reactor A. At a retention time of 10 days, the COD removals of reactors A, B, C and D were 38, 46, 51 and 52%, respectively. The gas productions of reactors B, C and D were, respectively, increased by 33, 30 and 163% over that of reactor A. The sludge dewaterability was examined by capillary suction rime (CST). The dewaterability of digested sludge was improved in reactors B, C and D. Capillary suction of digested sludges gave times in the range 148-389 s, compared with 309-735 s for undigested sludges. (C) 1997 Elsevier Science Ltd.
Handover management for a PCS network
(1997-12-01)
Noerpel, A
;
Lin, YB
;
交大名義發表
;
National Chiao Tung University
A handover is required in wireless personal communications systems when a portable moves from one base station coverage area to another during the course of a conversation. In general, the handover should be completed while the portable is in the overlap region to be successful. This article considers several issues for handover management, handover detection, channel assignment, and radio link transfer.
Multi-response robust design by principal component analysis
(1997-12-01)
Su, CT
;
Tong, LI
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Most previous Taguchi method applications have only addressed a single-response problem. However, more than one correlated response normally occurs in a manufactured product. The multi-response problem has received only limited attention. In this work, we propose an effective procedure on the basis of principal component analysis (PCA) to optimize the multi-response problems in the Taguchi method. With the PCA, a set of original responses can be transformed into a set of uncorrelated components. Therefore, the conflict for determining the optimal settings of the design parameters for the multi-response problems can be reduced. Two case studies are evaluated, indicating that the proposed procedure yields a satisfactory result.
Integrating order release control with due-date assignment rules
(1997-12-01)
Tsai, CH
;
Chang, GT
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This study integrates order release control methods with due-date assignment rules and assesses its impact on the accuracy of inter-operation time estimation and performance of due-date assignment. The assessment is made by using an experimental design with three due-date assignment rules, three scheduling rules and three order release models. The three order release models are: (1) Basic model, in which three due-date assignment rules consider the order arrival time as the order release time; (2) Control model, in which three due-date assignment rules integrate with the order release control method developed here; and (3) Adjustment model, in which the control model integrates with the order release control adjustment developed here. Simulation results in this study indicate that integrating the order release control method with due-date assignment rules will significantly enhance not only the accuracy of interoperation time estimation, but also the performance of due-date assignment rules.
Broadband service creation and operations
(1997-12-01)
Lin, YD
;
Lin, YT
;
Chen, PN
;
Choy, MM
;
資訊工程學系
Three challenges for deploying broadband services are the time-consuming process of service creation, the interoperability over heterogeneous platforms, and the gap between the needs of service management and the functionalities of network management. In this article we describe a methodology to attack the first two challenges, namely, to simplify the process of service creation and provide a platform-independent framework for service operations. A set of broadband service-independent building blocks (SIBs) are designed and used to create and customize SIB graphs for broadband services. During service running time, the service agent interprets a SIB graph and executes SIB procedures which are all downloaded from the service provider. Web, Java, and CORBA are the technological elements of this methodology. Two examples, video conferencing and video on demand, are given to demonstrate the feasibility of this approach.
Generating fuzzy rules from relational database systems for estimating null values
(1997-12-01)
Chen, SM
;
Yeh, MS
;
資訊工程學系
;
Department of Computer Science
This paper presents a new algorithm for constructing fuzzy decision trees from relational database systems and generating fuzzy rules from the constructed fuzzy decision trees. We also present a method for dealing with the completeness of the constructed fuzzy decision trees. Based on the generated fuzzy rules, we also present a method for estimating null values in relational database systems. The proposed methods provide a useful way to estimate null values in relational database systems.
An exact analysis of an asymmetric polling system with mixed service discipline and general service order
(1997-12-01)
Hwang, LC
;
Chang, CJ
;
電信工程研究所
;
電信研究中心
;
Institute of Communications Engineering
This paper derives the exact mean waiting time fur an asymmetric polling system with general service order and mixed service discipline. The mixed sen ice discipline means that the service discipline of each stage (a turn in the service order sequence) for the same station can be gated or exhaustive. The general service order denotes that each station can be polled more than once in a polling cycle. We use the mean age and the mean excess of a cumulative time to obtain the mean waiting times fur stages and stations, where the cumulative time for a stage is defined as the total arrival time period of all customers that are served at one visit of the server to the stage. The accuracy of our analysis is verified by comparisons with previously published results and simulation results. We also use a genetic algorithm (GA) to search for an optimal pattern of service order and service discipline For the asymmetrical polling system. The results of the paper can be applied to the design of computer communication networks with polling schemes. (C) 1997 Elsevier Science B.V.
Two-phase heat transfer characteristics for R-22/R-407C in a 6.5-mm smooth tube
(1997-12-01)
Wang, CC
;
Chiang, CS
;
機械工程學系
;
Department of Mechanical Engineering
Two-phase friction and heat transfer characteristics for R-22/R-407C inside a 6.5-mm smooth tube are reported in this study, The hear transfer results for G = 100 and 400 kg/m(2) s were reported in the present study, and the adiabatic frictional pressure drop was recorded in the range of 100 to 700 kg/m(2) s, It is found that the development of flow pattern for R-407C Falls behind R-22. This may explain the lower pressure drops for R-407C. The major heat transfer mechanism at low mass flux is nucleate boiling, and virtually becomes the convective evaporation as mass flux increase to G = 400 krg/m(2) s, Meanwhile, the reduction of heat transfer coefficients for R-407C mixtures are especially profound at low mass flux, and The reduction of heat transfer coefficient decreases with the increase of mass flux. (C) 1997 by Elsevier Science Inc.
A multiple criteria decision-making model for justifying the acceptance of rush orders
(1997-12-01)
Wu, MC
;
Chen, SY
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Rush orders are immediate customer demands that exceed the expectation of a currently effective MPS (master production schedule). Decision-makers are often hesitant in the decision of accepting such orders. This paper presents a multiple criteria decision-making model for justifying the acceptance of rush orders for an assembly-to-order production system. Four criteria or production objectives are simultaneously considered and a multiple objective programming technique, the e-constraints approach, is adopted to solve the decision-making problem. This model could give the cost estimation for producing a rush order under various combinations of production objectives. The computed cost value could serve as a Valuable reference for justifying the economics of accepting the rush order, and help to determine its pricing strategy.
Charging damages to gate oxides in a helicon O-2 plasma
(1997-12-01)
Lin, W
;
Kang, TK
;
Perng, YC
;
Dai, BT
;
Cheng, HC
After the exposure of metal oxide semiconductor (MOS) capacitors with antenna structures to the helicon O-2 plasma, the leakage current. charge-to-breakdown (Q(bd)) and capacitance-voltage (C-V) curves have been characterized to realize the charging damages. The results indicate that the quasi static C-V(QSCV) distortion and Q(bd) depend on the exposure time rather than the antenna ratio. The QSCV and Q(bd) Show a two stage degradation as the exposure time increases. The leakage current increases slightly for the specimens exposed to the plasma for less than 120 s, and increases considerably for the ones with the exposure time of 300 s. Based on these results, the degradation mechanism of gate oxides under the helicon O-2 plasma is established.
Optimal information-dispersal for increasing the reliability of a distributed service
(1997-12-01)
Sun, HM
;
Shieh, SP
;
資訊工程學系
;
Department of Computer Science
This paper investigates the (m,n) information dispersal scheme (IDS) used to support fault-tolerant distributed servers in a distributed system. In an (m, n)-IDS, a file M is broken into n pieces such that any m pieces collected suffice for reconstructing M. The reliability of an (m, n)-IDS is primarily determined by 3 important factors: n = information dispersal degree (IDD), n/m = information expansion ratio (IER), P-a = success-probability of acquiring a correct piece. It is difficult to determine the optimal IDS with the highest reliability from very many choices. Our analysis shows: several novel features of (m, n)-IDS which can help reduce the complexity of finding the optimal IDS with the highest reliability; that an IDS with a higher IER might not have a higher reliability, even when P-s-->1. Based on the theorems given herein, we have developed a method that reduces the complexity for computing the highest reliability from, O(v) [v = number of servers] to O(1) when the 'upper bound of the IER' = 1, or O(v(2)) to O(1) when the 'upper bound of the IER' > 1.
Tumbling/squish interaction in loop-scavenged two-stroke engines
(1997-12-01)
Tsui, YY
;
Cheng, HP
;
機械工程學系
;
Department of Mechanical Engineering
This article describes a numerical investigation of the flow in a loop-scavenged two-stroke engine equipped with a head-bowl combustion chamber. The bowl is either placed in the center of the cylinder head or displaced away from the center. Attention is focused on the period of compression and early expansion. Results show that the effects of compression of the tumbling vortex by the piston become prominent after the midcompression stage, resulting in significant cascading of energy from mean flow to turbulence, followed by a fast decay of turbulence. The subsequent emergence of squish and reverse squish helps retard die decay. As a consequence, the cases with head bowls possess higher levels of mean flow and turbulence than those without bowls at top dead center and the later stage. It is also shown in the results that the offset of the head bowl has significant effects on the mean flow and turbulence characteristics, highly dependent on the offset direction.
A new method for extracting the counter-implanted channel profile of enhancement-mode p-MOSFET's
(1997-12-01)
Wu, CM
;
Wu, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new methodology is proposed to extract the nonuniform channel doping profile of enhancement mode p-MOSFET's with counter implantation, based on the relationship between device threshold voltage and substrate bias. A self-consistent mathematical analysis is developed to calculate the threshold voltage and the surface potential of counter-implanted long-channel p-MOSFET at the onset of heavy inversion, Comparisons between analytic calculation and two-dimensional (2-D) numerical analysis have been made and the accuracy of the developed analytic model has been verified, Based on the developed analytic model, an automated extraction technique has been successfully implemented to extract the channel doping profile. With the aid of a 2-D numerical simulator, the subthreshold current can be obtained by the extracted channel doping profile. Good agreements have been found with measured subthreshold characteristics for both long-and short-channel devices, This new extraction methodology can be used for precise process monitoring and device optimization purposes.
Environment prediction for a mobile robot in a dynamic environment
(1997-12-01)
Chang, CC
;
Song, KT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The problem of navigating a mobile robot among moving obstacles is usually solved on the condition of knowing the velocity of obstacles. However, it is difficult to provide such information to a robot in real time. In this paper, we present an environment predictor that provides an estimate of future environment configuration by fusing multisensor data in real time. The predictor is implemented by an artificial neural network (ANN) trained using a relative-error-backpropagation (REBP) algorithm. The REBP algorithm enables the ANN to provide output data with a minimum relative error, which is better than conventional backpropagation (BP) algorithms in this prediction application. The mobile robot can, therefore, respond to anticipated changes in the environment. The performance is verified by prediction simulation and navigation experiments.
Flavor-changing neutral Higgs boson couplings and top-quark-charm-quark production at the Next Linear Collider
(1997-12-01)
Hou, WS
;
Lin, GL
;
Ma, CY
;
電子物理學系
;
物理研究所
We explore the possibility of detecting flavor-changing neutral Higgs boson couplings at the Next Linear Collider (NLC) through e(+)e(-)->nu(e)<(nu)over bar>(e)t (c) over bar. In the framework of a general two-Higgs-doublet model, we perform a complete calculation and find that sigma(e(+)e(-)-->nu(e) nu(e)t (c) over bar nu(e)<(nu)over bar>(e) (t) over bar c) could reach similar to 9 fb for root s=2 TeV. This amounts to an annual production of 500 t (c) over bar plus (t) over bar c pairs at the NLC with an integrated luminosity of 50 fb(-1). The dependence of the tc-production rate on the neutral scalar mixing angle is mild except when sin(2) alpha-->0 or 1. The nu nu W+W- background should be manageable after b tagging, while vvt (t) over bar background should not be a problem when the signal event rate is still interesting. The process, together with e(+)e(-)-->nu(e)<(nu(e))over bar>W+W-,nu(e)<(nu(e))over bar>ZZ studies, offer the chance of measuring the t-c-Higgs-bsson coupling.
Effect of direct-current biasing on the dielectric properties of barium strontium titanate
(1997-12-01)
Liou, JW
;
Chiou, BS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Ba1-xSrxTiO3 (BST, x = 0 to x = 1) ferroelectric ceramics doped with 1.0 mol% MgO and 0.05 mol% MnO2 were prepared with a rate-controlled sintering profile, As the strontium molar fraction x increased, the average grain size decreased from 14 mu m for x = 0 to 2 mu m for x = 1, Temperature dependence of the dielectric properties was measured as a function of de biasing, At 10 degrees C above the Curie temperature, the changes of dielectric constant at 5000 V/cm were 28%, 17%, 26%, and 36% for x = 0, 0.25, 0.5, and 0.75, respectively, The reduction of dielectric constant by the applied de biasing was fitted by a phenomenological equation that was based on Devonshire's theory, From this phenomenological equation, an anharmonic coefficient, which was an order parameter of the anharmonic interactions, was calculated for each composition, As the strontium molar fraction increased, these coefficients increased from 2.45 x 10(-19) cm(2).V-2 for x = 0 to 5.90 x 10(-19) cm(2).V-2 for x = 0.75, A similar trend was observed on the de field dependence of the dielectric loss, except at high field for x = 0, of which a high loss was obtained, A two-element circuit model was proposed to explain the effect of high de biasing on the dielectric loss.
Integrating order release control with due-date assignment rules
(1997-12-01)
Tsai, CH
;
Chang, GT
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This study integrates order release control methods with due-date assignment rules and assesses its impact on the accuracy of inter-operation time estimation and performance of due-date assignment. The assessment is made by using an experimental design with three due-date assignment rules, three scheduling rules and three order release models. The three order release models are: (1) Basic model, in which three due-date assignment rules consider the order arrival time as the order release time; (2) Control model, in which three due-date assignment rules integrate with the order release control method developed here; and (3) Adjustment model, in which the control model integrates with the order release control adjustment developed here. Simulation results in this study indicate that integrating the order release control method with due-date assignment rules will significantly enhance not only the accuracy of interoperation time estimation, but also the performance of due-date assignment rules.
Environment prediction for a mobile robot in a dynamic environment
(1997-12-01)
Chang, CC
;
Song, KT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The problem of navigating a mobile robot among moving obstacles is usually solved on the condition of knowing the velocity of obstacles. However, it is difficult to provide such information to a robot in real time. In this paper, we present an environment predictor that provides an estimate of future environment configuration by fusing multisensor data in real time. The predictor is implemented by an artificial neural network (ANN) trained using a relative-error-backpropagation (REBP) algorithm. The REBP algorithm enables the ANN to provide output data with a minimum relative error, which is better than conventional backpropagation (BP) algorithms in this prediction application. The mobile robot can, therefore, respond to anticipated changes in the environment. The performance is verified by prediction simulation and navigation experiments.
Fabrication of low-stress dielectric thin-film for microsensor applications
(1997-12-01)
Chou, BCS
;
Shie, JS
;
Chen, CN
;
光電工程研究所
;
Institute of EO Enginerring
A method of fabricating low-stress dielectric thin film as the supporting material of micromachined devices is reported. The film is processed by post thermal oxidation of silicon-rich nitride (SN) deposited on silicon substrate by LPCVD. Due to the compensation on the nitride by its top oxide, an ultra-low residual less than 10 MPa can be obtained with proper oxidation scheme. Characteristics of the oxidized nitride were analyzed by Auger electron spectroscopy (AES) and ellipsometry. Large floating membranes of 4 x 4 cm(2) and 400-nm thick can be made by this method with TMAH etching.