Browsing by Issue Date, starting with "2002-11-15"

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Optimization of the headspace solid-phase microextraction for determination of glycol ethers by orthogonal array designs
(2002-11-15)
Huang, CT
;
Su, YY
;
Hsieh, YZ
;
應用化學系
;
Department of Applied Chemistry
A headspace solid-phase microextraction (HS-SPME), in conjunction with gas chromatography-flame ionization detection for use in the determination of six frequently used glycol ethers at the mug/l level is described. A 75 mum Carboxen-polydimethylsiloxane fiber was used to extract the analytes from an aqueous solution. Experimental HS-SPME parameters such as extraction temperature, extraction time, salt concentration and sample volume, were investigated and optimized by orthogonal array experimental designs. The relative standard deviations for the reproducibility of the optimized HS-SPME method varied from 1.48 to 7.59%. The correlation coefficients of the calibration curves exceeded 0.998 in the mug/l range of concentration with at least two orders of magnitude. The method detection limits for glycol ethers in deionized water were in the range of 0.26 to 3.42 mug/l. The optimized method was also applied to the analysis of glycol ethers in urine and blood samples with the method detection limits ranged from 1.74 to 23.2 mug/l. (C) 2002 Elsevier Science B.V. All rights reserved.
Formation of phase grating in planar aligned cholesteric liquid crystal film
(2002-11-15)
Wu, JJ
;
Wu, YS
;
Chen, FC
;
Chen, SH
;
光電工程學系
Electric-field-induced cholesteric liquid crystal phase gratings were investigated by means of changing the film thickness-to-natural-pitch ratio d/p(0) and the applied voltage. Planar parallel (180degrees)-, antiparallel (0degrees)- and twist (90degrees)-aligned films were fabricated. By varying the d/p(0) value, we found that the stripes of the gratings could only be in two directions. It was interesting that the directions were mutually perpendicular. This device could be used as a grating switch.
Laser desorption/ionization time-of-flight mass spectrometry on sol-gel-derived 2,5-dihydroxybenzoic acid film
(2002-11-15)
Lin, YS
;
Chen, YC
;
應用化學系
;
Department of Applied Chemistry
This work presents a novel method for direct desorption/ ionization of analytes from sol-gel-derived film. 2,5-Dihydroxy benzoic acid (DHB), a common MALDI matrix, was incorporated into a sol-gel polymeric structure. The sol-gel-derived DHB thin film can assist the mass analysis of analytes by laser desorption/ionization, with a matrix interference-free background in the mass spectra. The sol-gel-derived film can function as an energy absorber during laser irradiation because it contains DHB molecules. Furthermore, laser irradiation with normal laser power (70 -110 muJ) is not likely to generate any background ions from this sol-gel-DHB derived film. The samples were prepared straightforwardly. After a thin film was formed on a Parafilm membrane from the sol-gel-derived DHB solution coating, the sample solution was directly added to the top of the film, for laser desorption/ ionization mass analysis. The analyte signals were homogeneously obtained on the sol-gel-derived DHB film. Experimental results show that the optimum concentrations of DHB incorporated in the sol-gel solution were between 7500 ppm and 10 000 ppm, providing a matrix interference-free background. Analytes, including small proteins, peptides, amino acids, and small organics, were used to demonstrate the effectiveness of the proposed method. However, a higher laser power (> 110 muJ) than normal was required to desorb small proteins from the sol-gel-derived DHB film. Therefore, a few matrix ions desorbed from the thin film were generated during laser irradiation. The detection limit for both small molecules and proteins, using this sol-gel-assisted laser desorption/ ionization (SGALDI) mass spectrometry (MS), was as low as 81 fmol. However, a mass spectrometer with cutoffmass selection could detect 8.1 fmol of cytochrome c. The largest analyte observed by the SGALDI-MS in this study was myoglobin.
Molecular dynamics analysis of effects of velocity and loading on the nanoindentation
(2002-11-15)
Fang, TH
;
Jian, SR
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
Three-dimensional molecular dynamics (MD) simulation is used to investigate the atomistic mechanism of nanoindentation process under various indentation loads and velocities that occur when a diamond tip interacts with the copper thin film. In this study, the model utilizes the Morse potential function to simulate interatomic forces between the specimen and tip. The results show that both Young's modulus and hardness increase up to a critical value and decrease there after for the indentation velocities, but decrease as the indentation loads increase. In additional, the contact stress-strain relationship is shown to be important.
Novel implantation method to improve machine-model electrostatic discharge robustness of stacked N-channel metal-oxide semiconductors (NMOS) in sub-quarter-micron complementary metal-oxide semiconductors (CMOS) technology
(2002-11-15)
Ker, MD
;
Hsu, HC
;
Peng, JJ
;
電機學院
;
College of Electrical and Computer Engineering
A novel ion implantation method for electrostatic discharge protection, often called as ESD implantation, is proposed to significantly improve machine-model (MM) ESD robustness of N-channel metal-oxide semiconductors (NMOS) device in stacked configuration (stacked NMOS). By using this ESD implantation method, the ESD current is discharged far away from the surface channel of NMOS, therefore the stacked NMOS in the mixed-voltage I/O interface can sustain a much higher ESD level, especially under the MM ESD stress. The MM ESD robustness of the stacked NMOS with a device dimension of W/L = 300 mum/0.5 mum for each NMOS has been successfully improved from the original 358 V to become 491 V in a 0.25-mum complementary metal-oxide semiconductors (CMOS) process.
Bulk and surface properties of layered silicates/fluorinated polyimide nanocomposites
(2002-11-15)
Jiang, LY
;
Wei, KH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Intercalated layered silicates/fluorinated polyimide nanocomposites with good overall properties are synthesized from organics-modified-montmorillonite and poly(amic acid), as confirmed by x-ray and transmission electron microscopy results. Both the bulk and surface (nanometer-domain) mechanical properties of synthesized silicates/fluorinated polyimide nanocomposites increased substantially as compared to that of pure polyimide. In particular, the Young's modulus and surface hardness of the fluorinated polyimide containing 5 wt % 2NH(2)-mont are 69% and 100% larger than that of pure polyimide, respectively. Additionally, the reduced elastic modulus by nanoindentation of the nanocomposites is 74% larger than that of the pure polyimide. The barrier properties of the nanocomposites, such as thermal expansion and water absorption retardation, are enhanced. (C) 2002 American Institute of Physics.
Self-healing fibre grating sensor system using tunable multiport fibre laser scheme for intensity and wavelength division multiplexing
(2002-11-21)
Peng, PC
;
Tseng, HY
;
Chi, S
;
光電工程學系
;
Department of Photonics
A fibre grating sensor system using a tunable multiport fibre laser scheme for intensity and wavelength division multiplexing is proposed. The power ratio (1:2:3) between each output port is used to address the sensing information. The network survivability is also considered. This fibre grating sensor system can enhance the sensing capacity and reliability.
Aqueous two-phase extraction as an effective tool for isolation of geniposide from gardenia fruit
(2002-11-22)
Pan, IH
;
Chiu, HH
;
Lu, CH
;
Lee, LT
;
Li, YK
Natural products are normally obtained by organic solvent extraction and many subsequent chromatographic separations. Compounds of interest are often isolated with very low yield and limited purity. An aqueous two-phase extraction process combined with a simple ethanol treatment, for removing excess inorganic salt, has been developed for preparation of geniposide from gardenia. The system was comprised of PE62, a random copolymer composed of 20% ethylene oxide and 80% propylene oxide, KH2PO4 and ethanol. To find optimal conditions, the partition behavior of geniposide under an aqueous two-phase system was investigated. Various factors were considered, including the concentration of salt, the concentration of polymer, the sample loading, and the addition of ethanol. The experimental results demonstrated that increasing salt concentration or decreasing PE62 concentration results in enhancement of the geniposide partition in the salt-rich phase. The addition of ethanol and higher sample loading also promoted the partition efficiency of geniposide. Based on this study, an optimized system containing 5% PE62, 7.5% KH2PO4, and 10% ethanol was tested on a large-scale extraction. A 39.0-g aliquot of final product (in powder form) with 77% purity of geniposide can be effectively extracted from 500 g of gardenia fruit. This process is proved to be useful for industrial application of geniposide preparation. (C) 2002 Elsevier Science B.V. All rights reserved.
Observation of the wave function of a quantum billiard from the transverse patterns of vertical cavity surface emitting lasers
(2002-11-25)
Huang, KF
;
Chen, YF
;
Lai, HC
;
Lan, YP
;
電子物理學系
We demonstrate experimentally that the near-field and far-field transverse patterns of a large aperture vertical cavity surface emitting laser (VCSEL) can be successfully interpreted as a two-dimensional (2D) billiard system. It is found that the near-field and far-field transverse patterns of a large aperture VCSEL evidently represent the coordinate-space and momentum-space wave functions of a 2D quantum billiard, respectively. The result of this paper suggests that large aperture VCSELs are potentially appropriate physical systems for the wave-function study in quantum problems.
Genetic algorithm-based neural fuzzy decision tree for mixed scheduling in ATM networks
(2002-12-01)
Lin, CT
;
Chung, IF
;
Pu, HC
;
Lee, TH
;
Chang, JY
Future broad-band integrated services networks based on the asynchronous transfer mode (ATM), technology are expected to support multiple types of multimedia information with diverse statistical characteristics and quality of service (QoS) requirements. To meet these requirements, efficient scheduling methods are important for traffic control in the ATM networks. Among the general scheduling schemes, the rate monotonic algorithm is simple enough to be used in high-speed networks, but it does not attain as high a system utilization as the deadline driven algorithm does. However, the deadline driven scheme is computationally complex and hard to implement in hardware. The mixed scheduling algorithm is the combination of the rate monotonic algorithm and the deadline driven algorithm; thus it can provide most of the benefits of these two algorithms. In this paper, we use the mixed scheduling algorithm to achieve high system utilization under the hardware constraint. Because there is no analytic method for the schedulability test of the mixed scheduling, we propose a genetic algorithm-based neural fuzzy decision tree (GANFDT) to realize it in a real-time environment. The GANFDT combines the GA and a neural fuzzy network into a binary classification tree. This approach also exploits the power of the classification tree. Simulation results show that the GANFDT provides an efficient way to carry out the mixed scheduling in the ATM networks.
Transformation mechanism of different chemically precipitated apatitic precursors into beta-tricalcium phosphate upon calcination
(2002-12-01)
Liou, SC
;
Chen, SY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The Ca-deficient apatite (CDHA) was prepared from the precursors of (CH3COO)(2)Ca - xH(2)O, Ca(NO3)(2).4H(2)O and H3PO4, (NH4)H2PO4 to investigate the transformation mechanism of beta-tricalcium phosphate (beta-TCP). X-ray diffraction analysis shows that the development of beta-TCP is not via direct reaction between Ca and P for all the different combinations between Ca and P precursors. The activation energy of beta-TCP formation with (NH4)H2PO4 as precursor was higher than that with H3PO4. Following the Johnson-Mehl-Avrami equation, the reaction kinetics of beta-TCP phase formation is found one-dimension growth with interface-controlled and diffusion controlled growth depending on the annealing temperature. There exists a transition between 750 degreesC and 825 degreesC, and the transition rate from interface-controlled to diffusion-controlled growth is precursor-dependent. (C) 2002 Elsevier Science Ltd. All rights reserved.
An adaptive sniff schedliling scheme for power saving in Bluetooth
(2002-12-01)
Lin, TY
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
Bluetooth is expected to be an important basic constructing component of smart homes. In a smart home environment, many devices will be portable and battery-operated, making power saving an essential issue. In this article we study the problem of managing the low-power sniff mode in Bluetooth, where a slave is allowed to be awake only periodically. One challenging problem is how to schedule each slave's sniffing period in a piconet so as to resolve the trade-off between traffic and power-saving requirements, to which we refer as the sniff-scheduling problem. We propose an adaptive protocol to dynamically adjust each slave's sniff parameters, with a goal of catching the varying, and even asymmetric, traffic patterns among the master and slaves. Compared to existing works, our work is unique. First, our scheduling considers multiple slaves simultaneously. Existing work only considers one slave, and different slaves are treated independently. Second, our scheduling is more accurate and dynamic in determining the sniff-related parameters based on slaves' traffic patterns. Most work is restricted to a naive exponential adjustment in sniff interval/sniff-attempt window. Third, our proposal includes the placement of sniff-attempt periods of sniffed slaves on the time axis when multiple slaves are involved. This issue is ignored by earlier work. Extensive simulation results are presented. Among many observations, one interesting result is that with proper settings, our protocol can save significant power while achieving higher network throughput than a naive always active round-robin scheme.
Engineering phosphors for improved brightness
(2002-12-01)
Lin, CH
;
Chiou, BS
;
Lin, JD
;
電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Factors affecting the cathodoluminescent (CL) efficiency of phosphors include: morphology, size, stoichiometry, composition, and surface of the phosphors. In the design of phosphors for low-voltage operations, processes such as surface etching are used to enhance phosphor efficiency. In this study, zinc-activated ZnO phosphors were subjected to three processes: acid etching, ball milling, and/or ultrasonic vibration, and the effect of each process on the CL efficiency studied. It is found that the brightness of phosphors increases 40% after ultrasonic vibration followed by etching twice with 0.005 M HNO3. (C) 2002 Kluwer Academic Publishers.
RPIM-SM: extending PIM-SM for RP relocation
(2002-12-01)
Lin, YD
;
Hsu, NB
;
Hwang, RH
;
資訊工程學系
;
Department of Computer Science
The protocol independent multicast-sparse mode (PIM-SM) protocol establishes core-base tree to forward multicast datagrams in a network. In PIM-SM, the core or rendezvous point (RP) of a group is determined at each multicast router by hashing a group address, i.e. a class-D IP address, to one of the candidate RPs. The hash function is characterized by its ability to evenly and uniquely choose the core for a group and remains insensitive to the geographic distribution of the group members and the sources. However, it may result in a multicast tree with high cost. This study presents a relocation mechanism, which is extension to PIM-SM, in which RP could be relocated periodically. When a new RP is found, the original RP informs all members to re-join to the new RP. Simulation results indicate that the extended version, RPIM-SM, reduces about 20% tree cost than PIM-SIM when the group size is medium. Moreover, comparing RPIM-SM with the optimal core-based tree reveals that they have less than 5% difference in tree cost. Furthermore, an increase of the number of candidate RPs brings RPIM-SM even closer to the optimal core-based tree. Results in this study demonstrate that relocation improve the performance of PIM-SM. (C) 2002 Published by Elsevier Science B.V.
Minimizing weighted earliness and tardiness penalties in single-machine scheduling with idle time permitted
(2002-12-01)
Chen, JY
;
Lin, SF
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, a single-machine scheduling problem with weighted earliness and tardiness penalties is considered. Idle time between two adjacent jobs is permitted and due dates of jobs could be unequal. The dominance rules are utilized to develop a relationship matrix, which allows a branch-and-bound algorithm to eliminate a high percentage of infeasible solutions. After combining this matrix with a branching strategy, a procedure to solve the problem is proposed. (C) 2002 Wiley Periodicals, Inc.
Unloading law for a LEO spacecraft with two-gimbals solar array
(2002-12-01)
Jan, YW
;
Chiou, JC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The purpose of this paper is to present a modified cross-product unloading law that can be used to provide an open-loop compensation control design to counteract the predominant effects of the gravity gradient torque. The modified cross-product unloading law, is successfully applied to a three-axis stabilized, nadir-pointed LEO spacecraft with two-gimbals solar array. The variation of the two solar array orientations can significantly change the spacecraft's moment of inertia during the nominal operation mode, which can produce significant momentum accumulation in the roll-yaw body plane and cause large yaw pointing error. A rigorous study of momentum management performance capability has been conducted by using a high-fidelity performance simulation software that contains models of four environmental disturbance torque (gravity gradient, aerodynamic, solar, and magnetic). The simulation results show that the proposed momentum unloading control law has enabled a substantial reduction in the maximum accumulated roll momentum, which results in improving the pointing accuracy of the LEO spacecraft enormously. (C) 2002 Published by Elsevier Science Ltd.
Effects of surfactant addition on dewatering of alum sludges
(2002-12-01)
Huang, C
;
Pan, JR
;
Fu, CG
;
Wu, CC
;
環境工程研究所
In Taiwan, surfactants are frequently used in the flotation process to aid in solid/liquid separation. Their effect on the dewatering of alum sludge was investigated. Various amounts of cationic and anionic surfactants were added to sludge samples, and the dewatering characteristics of the sludge and the water content of sludge cakes were evaluated. Both surfactants improved the dewatering of the sludge by lowering the specific resistance to filtration, decreasing the bound water content, and increasing the dewatering rate of the sludge. Different combinations of anionic and cationic surfactants and polyelectrolytes were also experimented on to study the effect of surfactant addition on the dewatering characteristics of polyelectrolyte-conditioned sludge. Experimental results indicated that both cationic and anionic surfactants adversely affected the dewatening of the conditioned sludge. The addition of surfactant to the oppositely charged polyelectrolyte proved to be most detrimental to sludge dewatering due to the precipitation between surfactant and polyelectrolyte. The addition of cationic surfactant to the cationic polyelectrolyte-conditioned sludge had the least effect.
缸
(2002-12-01)
管管
A learnable cellular neural network structure with ratio memory for image processing
(2002-12-01)
Wu, CY
;
Cheng, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, a learnable cellular neural network (CNN) with space-variant templates and ratio memory (RM) called the RMCNN, is proposed and analyzed. By incorporating both modified Hebbian learning rule and RM into CNN architecture, the RMCNN as the associative memory can generate the absolute weights and then transform them into the ratioed A-template weights as the ratio memories for recognition of noisy input patterns. It is found from simulation results that due to the feature enhancement effect of RM, the RMCNN under constant leakage on template coefficients can store and recognize more patterns than the CNN associative memories without RM, but with the same learning rule and the same constant leakage on space-variant template coefficients. For 9 x 9 (18 x 18) RMCNNs, three (five) patterns can be learned, stored and recognized. Based upon the RMCNN architecture, an experimental chip of CMOS 9 x 9 RMCNN is designed and fabricated by using 0.35 mum CMOS technology. The measurement results have successfully verified the correct functions of RMCNN.
Fuzzy multiple-criteria decision-making approach for industrial green engineering
(2002-12-01)
Chiou, HK
;
Tzeng, GH
;
運輸與物流管理系註：原交通所+運管所
;
科技管理研究所
;
Department of Transportation and Logistics Management
This paper describes a fuzzy hierarchical analytic approach to determine the weighting of subjective judgments. In addition, it presents a nonadditive fuzzy integral technique to evaluate a green engineering industry case as a fuzzy multicriteria decision-making (FMCDM) problem. When the investment strategies are evaluated from various aspects, such as economic effectiveness, technical feasibility, and environmental regulation, it can be regarded as an FMCDM problem. Since stakeholders cannot clearly estimate each considered criterion in terms of numerical values for the anticipated alternatives/strategies, fuzziness is considered to be applicable. Consequently, this paper uses triangular fuzzy numbers to establish weights and anticipated achievement values. By ranking fuzzy weights and fuzzy synthetic utility values, we can determine the relative importance of criteria and decide the best strategies. This paper applies what is called a X fuzzy measure and nonadditive fuzzy integral technique to evaluate the synthetic performance of green engineering strategies for aquatic products processors in Taiwan. In addition, we demonstrate that the nonadditive fuzzy integral is an effective evaluation and appears to be appropriate, especially when the criteria are not independent.