Browsing by Issue Date, starting with "1999-02-01"

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Blind adaptive algorithm for demodulation of DS/CDMA signals with mismatch
(1999-02-01)
Hwang, HC
;
Wei, CH
;
電子工程學系及電子研究所
;
電信研究中心
;
Department of Electronics Engineering and Institute of Electronics
The minimum mean-squared error (MMSE) linear detector is known to be a near-far resistant strategy for direct-sequence code-division multiple access systems. The MMSE linear detector can be implemented adaptively by the MOE adaptation algorithm or the Griffiths' adaptation algorithm, which utilises the desired signal vector for initial adaptation instead of training sequences, The performance loss caused by the imprecise knowledge of the desired signal vector is investigated. A new blind adaptive algorithm is presented to mitigate the effect of the mismatch caused by the timing error in acquisition. Several;numerical results show that the new algorithm can provide a resistance to the effect of mismatch compared to the MOE and Griffiths' algorithms.
The behavior of a compressible silty fine sand
(1999-02-01)
Huang, AB
;
Hsu, HH
;
Chang, JW
;
土木工程學系
;
Department of Civil Engineering
Publications associated with sands are often limited to clean (i.e., little fines content), uniform, uncemented silica or quartz sand. On the other hand, the importance of mineral content, particle shapes, as well as gradation to the behavior of sand has long been recognized. Although systematic studies of sands ether than clean quartz sand have been limited, there is increasing attention being paid to sands with an appreciable fines content. Because of a major construction project, extensive field and laboratory experiments were performed on a silty fine sand from Mai-Liao, which is located on the central west coast of Taiwan. Results show that Mai-Liao Sand (MLS), a silty sand, can be significantly more compressible than clean quartz sand under static load. The particles of MLS have moderate strength, and significant crushing can be induced by triaxial shearing. As a result, MLS has low dilatancy and a relatively small range of peak friction angles. Cone penetration tests in MLS were conducted in a calibration chamber. Analyses of the data indicate that interpreting cone tip resistance in MLS using methods developed based on clean quartz sand without considering the differences of compressibility can be unrealistic. This paper documents results of the experimental studies on MLS.
Treatment of high strength hexamine-containing wastewater by Electro-Fenton method
(1999-02-01)
Chou, SS
;
Huang, YH
;
Lee, SN
;
Huang, GH
;
Huang, CP
A novel Electro-Fenton (EF-Fere) method, applied H2O2 and electrogenerated ferrous ion, was investigated for treating the hexamine-containing wastewater. The performance of Fe2+ generation in the electrolytic system was first evaluated, including the factors of the cathode material, initial pH, initial ferric concentration (Fe-i), and current density. When initial pH exceeded 2.5, the current efficiency dramatically decreased, which was due to the formation of Fe(OH)(3). Between 3000 and 10,000 mg/l of Fe-i, the initial current efficiency of Fe2+ generation was almost constant (85-87%), which dropped sharply to 39% at 1000 mg/l. In EF-Fere experiments, the COD removal efficiency attained above 94% after 5 h of reaction. The relationship between the temperature, dissolved oxygen, and COD was discussed. The changes in hexamine and its oxidation intermediates (methanol, formaldahyde, formate, ammonium and nitrate) during the reaction were also investigated. Three additional experiments using H2O2/Fe2+, H2O2/Fe3+, and direct electrolysis were also conducted to treat the hexamine-containing wastewater for comparison. The results showed that the EF-Fere method was the most efficient. (C) 1998 Elsevier Science Ltd. All rights reserved.
An explicit approximation to the wavelength of nonlinear waves
(1999-02-01)
Chang, HK
;
Lin, SC
;
土木工程學系
;
Department of Civil Engineering
An explicit and concise approximation to the wavelength in which the effect of nonlinearity is involved and presented in terms of wave height, wave period, water depth and gravitational acceleration. The present approximation is in a rational form of which Fenton and Mckee's (1990, Coastal Engng 14, 499-513) approximation is reserved in the numerator and the wave steepness is involved ill the denominator. The rational form of this approximation can be converted to an alternative form of a power-series polynomial which indicates that the wavelength increases with wave height and decreases with water depth. If the determined coefficients in the present approximation are fixed, the approximating formula can provide a good agreement with the: wavelengths numerically obtained by Rienecker and Fenton's (1981, J. Fluid Mech. 104, 119-137) Fourier series method, but has large deviations when waves of small amplitude are in deep water or all waves are in shallow water, The present approximation with variable coefficients can provide excellent predictions of the wavelengths for both long and short waves even, for high waves. (C) 1998 Elsevier Science Ltd. All rights reserved.
Finding inheritance hierarchies in fuzzy-valued concept-networks
(1999-02-01)
Horng, YJ
;
Chen, SM
;
資訊工程學系
;
Department of Computer Science
In this paper, we extend the works of [2] and [4] to present a new method for finding the inheritance hierarchies in fuzzy-valued concept-networks, where the relevant values (degrees of generalization or degrees of similarity) between concepts in a fuzzy-valued concept network are represented by fuzzy numbers. The proposed method is more flexible than the ones presented in [2] and [4] due to the fact that it allows the grades of similarity and the grades of generalization between concepts to be represented by fuzzy numbers rather than crisp real values between zero and one or interval values in [0, 1].
Design of dynamic-floating-gate technique for output ESD protection in deep-submicron CMOS technology
(1999-02-01)
Chang, HH
;
Ker, MD
;
Wu, JC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A novel dynamic-floating-gate technique is proposed to improve ESD robustness of the CMOS output buffers with small driving/sinking currents. This dynamic-floating-gate design can effectively solve the ESD protection issue which is due to the different circuit connections on the output devices. By adding suitable time delay to dynamically float the gates of the output NMOS/PMOS devices which are originally unused in the output buffer, the human-body-model (machine-model) ESD failure threshold of a 2-mA output buffer can be practically improved from the original 1.0 kV (100 V) up to greater than 8 kV (1500 V) in a 0.35-mu m bulk CMOS process. (C) 1998 Elsevier Science Ltd. All rights reserved.
Construct message authentication code with one-way hash functions and block ciphers
(1999-02-01)
Yeh, YS
;
Wang, CC
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
We suggest an MAC scheme which combines a hash function and an block cipher in order. We strengthen this scheme to prevent the problem of leaking the intermediate hash value between the hash function and the block cipher by additional random bits. The requirements to the used hash function are loosely. Security of the proposed scheme is heavily dependent on the underlying block cipher. This scheme is efficient on software implementation for processing long messages and has clear security properties.
Quasi-two-dimensional simulation of scour and deposition in alluvial channels - Closure
(1999-02-01)
Lee, HY
;
Hsieh, HM
;
Yang, JC
;
Yang, CT
;
土木工程學系
An expert-system technique for object-oriented program testing
(1999-02-01)
Chen, WC
;
Chen, DJ
;
Chung, CG
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
Data abstraction, information hiding, inheritance, and dynamic binding are four basic elements used in designing object-oriented (OO) programs. These four mechanisms enable programmers to write object-oriented programs that are easily extended, reused and maintained. Software implemented by OO methodologies has increased software quality and productivity.(1) However, this cannot be guaranteed without an appropriate software testing approach. Traditional testing approaches cannot be applied directly to the testing of OO programs due to the OO characteristics used in these programs. OO program testing strategies and methods are proposed continually, but fewer OO testing tools with flexibility are discussed.
Chromic acid removal by anion exchange
(1999-02-01)
Tan, HKS
;
應用化學系
;
Department of Applied Chemistry
The kinetics of dilute chromic acid removal by anion exchange was studied using a batch system. Rate model formulated for total Cr(VI) removal based on film diffusion control was applied. This rate model was shown to adequately fit the experimental rate data. In addition, column experimental runs were performed by using 20-50 mesh anion resin with feed solution containing 0.2 g/L CrO3. The bed heights of 15, 25 and 35 cm and flow rates ranging from 1.02 cm/s to 2.38 cm/s were employed in the experiments. Linear driving force rate expression based on film diffusion rate control was incorporated in the model equations for simulation of column performance. The kinetic parameter and equilibrium relation in the rate equation were obtained independently either by separate experiments or from data available in the literature. Satisfactory agreements between experimental and calculated breakthrough curves were obtained.
Recursive constructions for perfect secret sharing schemes
(1999-02-01)
Sun, HM
;
Shieh, SP
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資訊工程學系
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Department of Computer Science
A secret sharing scheme is a method which allows a secret to be shared among a set of participants in such a way that only qualified subsets of participants can recover the secret. A secret sharing scheme is called perfect if unqualified subsets of participants obtain no information regarding the secret. The information rate of a secret sharing scheme is defined to be the ratio between the size of secret and the maximum size of the shares. In this paper, we propose some recursive constructions for perfect secret sharing schemes with access structures of constant rank. Compared with the best previous constructions, our constructions have some improved lower bounds on the information rate. (C) 1999 Elsevier Science Ltd. All rights reserved.
Elastic solutions for a transversely isotropic half-space subjected to buried asymmetric-loads
(1999-02-01)
Wang, CD
;
Liao, JJ
;
土木工程學系
;
Department of Civil Engineering
Elastic closed-form solutions for the displacements and stresses in a transversely isotropic half-space subjected to various buried loading types are presented. The loading types include finite line loads and asymmetric loads (such as uniform and linearly varying rectangular loads, or trapezoidal loads). The planes of transverse isotropy are assumed to be parallel to its horizontal surface. These solutions are directly obtained from integrating the point load solutions in a transversely isotropic half-space, which were derived using the principle of superposition, Fourier and Hankel transformation techniques. The solutions for the displacements and stresses in transversely isotropic half-spaces subjected to linearly variable loads on a rectangular region are never mentioned in literature. These exact solutions indicate that the displacements and stresses are influenced by several factors, such as the buried depth, the loading types, and the degree and type of rock anisotropy. Two illustrative examples, a vertical uniform and a vertical linearly varying rectangular load acting on the surface of transversely isotropic rock masses, are presented to show the effect of various parameters on the Vertical surface displacement and vertical stress. The results indicate that the displacement and stress distributions accounted for rock anisotropy are quite different for those calculated from isotropic solutions. Copyright (C) 1999 John Wiley & Sons, Ltd.
Cloning and expression of beta-glucosidase from Flavobacterium meningosepticum: A new member of family B beta-glucosidase
(1999-02-01)
Li, YK
;
Lee, JA
;
應用化學系
;
Department of Applied Chemistry
A beta-glucosidase gene from Flavobacterium meningosepticum has been cloned and expressed in Escherichia coli. The Entire nucleotide sequence was determined and analyzed. An open-reading frame of 2,178 bp encoding a polypeptide of 726 amino acids with a calculated M-r of 79,952 was derived from the sequence. The coding region is flanked by a putative promoter and transcription terminator sequences. The nucleotide sequence accession number of the complete gene sequence in Genbank is AF015915. Based on the comparison of amino acid sequences this enzyme is classified as a family B beta-glucosidase and is highly homologous with sequences from Clostridium thermocellum, Kluyvermyces fragilis, and Agrobacterium tumefaciens. The cloned enzyme was purified to near homogeneity by ammonium sulfate fractionation (35 similar to 75%) and chromatography an a cation-exchanged column at pH 6.9. This expressed beta-glucosidase has optimum activity at pH 4.2 similar to 5.0 and 50 degrees C and is stable in the pH range of 5.0 similar to 8.1 at 25 degrees C. it showed a high specificity on the glycone portion of aryl-beta-D-glycosides. All of these characteristics are highly consistent with those of the native beta-glucosidase. (C) 1998 Elsevier Science inc.
Formation behavior of high-T-c Tl-based superconductors
(1999-02-01)
Koo, HS
;
Lo, JR
;
Tseng, TY
;
Lin, CS
;
電子工程學系及電子研究所
The effects of Ca, Cu, and Ca-Cu richness on the formation behavior and physical characteristics of high-T-c Tl-based superconductors were investigated systematically. In addition to sintering temperature and time, intermediate phases which proved important to the formation and properties of nearly single-phase, triple-CuO-layers Tl2Ba2Ca2Cu3Oy superconductors and optimal processing conditions were also investigated. Ca and Ca-Cu richness introduced positive effects on the properties of nearly single-phase Tl2Ba2Ca2Cu3Oy superconductors and helps in the formation of the appropriate intermediate phases, whereas Cu richness produced a negative effect. The higher sintering temperatures of the specimens accounted for the tailing of electrical resistance before the critical zero resistance temperature was approached, and for the instability of the superconducting phase. Lower post-annealing temperatures of the bulk samples slightly improved the superconducting properties. The resultant bulk Tl-based superconductors can be used as a Tl vapor source for the formation of superconducting thin films within a closed system.
A QoS-provisioning neural fuzzy connection admission controller for multimedia high-speed networks
(1999-02-01)
Cheng, RG
;
Chang, CJ
;
Lin, LF
;
電信工程研究所
;
電信研究中心
This paper proposes a neural fuzzy approach for connection admission control (CAC) with QoS guarantee in multimedia high-speed networks. Fuzzy logic systems have been successfully applied to deal with traffic-control-related problems and have provided a robust mathematical framework for dealing with real-world imprecision. However, there is no clear and general technique to map domain knowledge on traffic control onto the parameters of a fuzzy logic system. Neural networks have learning and adaptive capabilities that can be used to construct intelligent computational algorithms for traffic control. However, the knowledge embodied in conventional methods is difficult to incorporate into the design of neural networks. The proposed neural fuzzy connection admission control (NFCAC) scheme is an integrated method that combines the linguistic control capabilities of a fuzzy logic controller and the learning abilities of a neural network. It is an intelligent implementation so that it can provide a robust framework to mimic experts' knowledge embodied in existing traffic control techniques and can construct efficient computational algorithms for traffic control. We properly choose input variables and design the rule structure for the NFCAC controller so that it can have robust operation even under dynamic environments. Simulation results show that compared with a conventional effective-bandwidth-based CAC, a fuzzy-logic-based CAC, and a neural-net-based CAC, the proposed NFCAC can achieve superior system utilization, high learning speed, and simple design procedure, while keeping the QoS contract.
Singular unitary dilations
(1999-02-01)
Wu, PY
;
Takahashi, K
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應用數學系
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Department of Applied Mathematics
We study the problem of determining which bounded linear operator on a Hilbert space can be dilated to a singular unitary operator. Same of the partial results we obtained are (1) every strict contraction has a diagonal unitary dilation, (2) every C-0 contraction has a singular unitary dilation, and (3) a contraction with one of its defect indices finite has a singular unitary dilation if and only if it is the direct sum of a singular unitary operator and a C-0(N) contraction. Such results display a scenario which is in marked contrast to that of the classical case where we have the absolute continuity of the minimal unitary power dilation of any completely nonunitary contraction.
On an unbalanced growth curve model with random effects and AR(1) errors from a Bayesian and the ML points of view
(1999-02-01)
Lee, JC
;
Niu, WF
;
統計學研究所
;
Institute of Statistics
In this paper we consider a Bayesian analysis of unbalanced (general) growth curve model with random effects and AR(I) errors. Three priors are proposed and put into comparisons in parameter estimation and prediction problems. (C) 1999 Elsevier Science B.V. All rights reserved.
An intelligent supervisory system for ion implantation in IC fabrication processes
(1999-02-01)
Shen, LC
;
Hsu, PL
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電控工程研究所
;
Institute of Electrical and Control Engineering
This pager presents a real-time intelligent supervision system for IC ion implantation processes. A hardware interface is developed, to extract the features directly from the 2-D analog image signals of a beam map. A qualitative model for the beam scanning is then obtained, and the symptoms of abnormal operations can be analyzed to achieve on-line diagnosis. Furthermore, a fuzzy expert system is developed to advise operators on making appropriate adjustments for the beam scanning. This supervisory system has been implemented on Eaten NV-6200 A/AV ion implanters at the Taiwan Semiconductor Manufacturing Company. (C) 1999 Elsevier Science Ltd. All rights reserved.
Semi-IPNs formed from poly(ethylene glycol monomethyl ether acrylate) and an epoxy thermoset
(1999-02-01)
Lin, MS
;
Liu, CC
;
應用化學系
;
Department of Applied Chemistry
Poly(ethylene glycol monomethyl ether acrylate) (PEGMEA) was synthesized from the reaction of poly(ethylene glycol monomethyl ether) (PEGME) with acryloyl chloride. Semi-IPNs based on various weight ratios of diglycidyl ether of bisphenol A (DGEBA)/PEGMEA were prepared, using isophronediamine (IPDA) and 2,2'-azo-bis (isobutyronitrile) (AIBN) as curing agents. The glass transition temperature and exothermic peak shifts were studied with differential scanning calorimetry (DSC). Viscosity changes during semi-IPN formation were measured with a Brookfield viscometer. Dynamic mechanical properties were investigated by rheometric dynamic spectroscopy (RDS). Stress-strain curves were obtained with an Instron tensile tester, while impact resistance was measured with a computer aided falling dart impact tester. Experimental results revealed retarded curing rates for all semi-IPNs, as evidenced from the shifts of curing exothermic peaks to higher temperatures, together with retarded viscosity increases during semi-IPN formation. These phenomena were interpreted in terms of chain entanglement between epoxy and PEGMEA. Nevertheless, the semi-IPNs indicated good compatibility as inferred from a single T-g in DSC and a single damping peak in RDS for each semi-IPN. Improved tensile stress and strain along with toughness improvements were noticed for this semi-IPN system. Shear band yielding was proposed to interpret this result. (C) 1999 Society of Chemical Industry.
Condensation heat transfer and pressure drop of refrigerant R-134a in a small pipe
(1999-02-01)
Yan, YY
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
The characteristics of condensation heat transfer and pressure drop for refrigerant R-134a flowing in a horizontal small circular pipe that has an inside diameter of 2.0 mm were investigated experimentally in this study. The effects of the heat flux, mass flux, vapor quality and saturation temperature of R-134a on the measured condensation heat transfer and pressure drop were examined in detail. When compared with the data for a large pipe (D-i = 8.00 mm) reported in the literature, the condensation heat transfer coefficient averaging over the entire quality range tested here for the small pipe is about 10% higher. Moreover, we noted that in the small pipe the condensation heat transfer coefficient is higher at a lower heal flux, at a lower saturation temperature and at a higher mass flux. In addition, the measured pressure drop is higher for raising the mass flux but lower for raising the heat flux. Based on the present data, empirical correlation equations were proposed for the condensation heat transfer coefficient and friction factors. The results are useful in designing more compact and effective condensers for various refrigeration and air conditioning systems using refrigerant R-134a. (C) 1998 Elsevier Science Ltd. All rights reserved.