Browsing by Issue Date, starting with "2000-08-01"

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Influence of solid content on bioleaching of heavy metals from contaminated sediment by Thiobacillus spp
(2000-08-01)
Chen, SY
;
Lin, JG
;
環境工程研究所
;
Institute of Environmental Engineering
The bioleaching process is one of the promising methods for removing heavy metals from contaminated sediments. In this study the effects of sediment solid content on the performance of the bioleaching process using a mixed culture of two sulfur-oxidizing bacteria were investigated. The results showed that the rate of pH reduction decreased with increasing sediment solid content because of the buffering capacity of sediment solids. It was found that there was a linear relationship between buffering capacity and sediment solid content. For different solid contents (10-100gdm(-3)), 82-95% (w/w) of Cu; 58-70% (w/w) of Zn; 55-73% (w/w) of Mn; 33-72% (w/w) of Pb; 35-65% (w/w) of Ni and 9-20% (w/w) of Cr were leached from sediments in this bioleaching process. The rate of metal leaching was found to decrease with an increase in sediment solid content. The solubilization of heavy metal from sediments was well described by a solid content-related kinetic equation. (C) 2000 Society of Chemical Industry.
Carrier-to-interference ratio measurement using moments or histograms
(2000-08-01)
Su, YT
;
Chen, JY
;
電信工程研究所
;
Institute of Communications Engineering
Cochannel interference is often the predominant factor that limits the capacity of a cellular mobile radio system. Power control is thus needed so that carrier-to-cochannel interference ratio (CIR) can be maintained within a tolerable bound. Many power control algorithms that require real-time CIR measurement have been proposed but there is very few mentioning of the measurement method, This paper presents viable solutions for real-time CIR estimations under various channel conditions. These solutions are based on either the method of moments or the histogram matching concept. We provide numerical results to demonstrate the usefulness and to compare the performance of the proposed algorithms. It is found that the histogram matching method with a properly-designed nonuniform quantizer offers excellent CIR estimation.
Dissociation kinetics of cerium(III) complexes of macrocyclic polyaza polycarboxylate ligands TETA and DOTA
(2000-08-01)
Chang, CA
;
Liu, YL
;
生物科技學系
;
Department of Biological Science and Technology
The acid-catalyzed dissociation rate constants of the cerium(III) complexes of 1,4,8,11-tetraazacyclotetradecane-1,4, 8,11-tetraacetic acid (TETA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) have been determined at four different temperatures (i.e., 25.0 degreesC, 32.0 degreesC, 39.0 degreesC, 45.0 degreesC) in aqueous media (mu = 0.10 M, HCl/KCl) to obtain additional kinetic data and to evaluate possible effects of ligand pre-organization for metal ion complexation. The rates are much faster for Ce(TETA)(-) than for Ce(DOTA)(-), indicating the lower thermodynamic stability of the former. In the presence of excess strong acid, 0.1 - 1.0 M HCl, the dissociation reactions follow the rate law: -d[ML]T/dt = (k(d) + k(H)[H+])[ML](T) and -d[ML]T/dt = (k(H)[H+] + k(H2)[H+](2))[ML](T), respectively, where k(d) is acid-independent dissociation reaction rate constant and k(H) and k(H2) are the respective dissociation rate constants for the pathways involving monoprotonated and diprotonated species. The rate activation parameters, DeltaH(not equal), DeltaS(not equal) and DeltaG(not equal), for each dissociation pathway have been obtained and their values are consistent with the proposed mechanisms. In particular, the rate difference between Ce(TETA)(-) and Ce(DOTA)(-) for the monoprotonated complex dissociation pathway is mainly due to difference in DeltaH(H)(not equal). If has been concluded that ligand pre-organization results in more stable complexes and slower complex dissociation rates.
ALTO: An iterative area/performance tradeoff algorithm for LUT-based FPGA technology mapping
(2000-08-01)
Huang, JD
;
Jou, JY
;
Shen, WZ
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, we propose an iterative area/performance tradeoff algorithm for look-up table (LUT)-based held programmable gate array (FPGA) technology mapping. First, it finds an area-optimized, performance-considered initial network by a modified area optimization technique. Then, an iterative algorithm consisting of several resynthesizing techniques is applied to trade the area for the performance in the network gracefully. Experimental results show that this approach can efficiently provide a complete set of mapping solutions from the area-optimized one to the performance-optimize one for the given design. Furthermore, these two extreme solutions produced by our algorithm outperform the results provided by most existing algorithms. Therefore, our algorithm is very useful for the timing-driven, LUT-based FPGA synthesis.
Determination of the optimal dose of polyelectrolyte sludge conditioner considering particle sedimentation effects
(2000-08-01)
Wu, CC
;
Lee, DJ
;
Huang, CP
;
環境工程研究所
;
Institute of Environmental Engineering
The specific resistance to filtration (SRF) of sludge was determined using both a leaf filter and a Buncher funnel. The filterability of a kaolin suspension and an alum sludge were characterized using SRF data and capillary suction time (CST) measurements. Filter orientation during the leaf filter test and stirring during the Buncher funnel test affected the SRF values, and the optimal dosage of polyelectrolyte conditioner (defined as the dosage that yields the minimum resistance to filtration) varied depending on the type of test used. Therefore, the optimal dose of polyelectrolyte was an operationally defined value that depended on the geometry of the filter chamber and fluid/particle interactions, such as sedimentation. (C) 2000 Elsevier Science Ltd. All rights reserved.
Robust ultrathin oxynitride dielectrics by NH3 nitridation and N2O RTA treatment
(2000-08-01)
Pan, TM
;
Lei, TF
;
Chao, TS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, a method to grow robust ultrathin (E-OT = 28 Angstrom) oxynitride film with effective dielectric constant of 5.7 is proposed, Samples, nitridized by NH3 with additional N2O annealing, show excellent electrical properties in terms of very low bulk trap density, low trap generation rate, and high endurance in stressing. This novel dielectric appears to be very promising for future ULSI devices.
ESD protection design on analog pin with very low input capacitance for high-frequency or current-mode applications
(2000-08-01)
Ker, MD
;
Chen, TY
;
Wu, CY
;
Chang, HH
;
電子工程學系及電子研究所
An electrostatic discharge (ESD) protection design is proposed to solve the ESD protection challenge to the analog pins for high-frequency or current-mode applications. By including an efficient power-rails clamp circuit into the analog input/output (I/O) pin, the device dimension (W/L) of an ESD clamp device connected to the I/O pad in the analog ESD protection circuit can be reduced to only 50/0.5 (mu m/mu m) in a 0.35-mu m silicided CMOS process, but it can sustain the human body model (HBM) and machine model (MM) ESD level of up to 6 kV (400 V). With such a smaller device dimension, the input capacitance of this analog ESD protection circuit can be significantly reduced to only similar to 1.0 pF (including the bond-pad capacitance) for high-frequency applications.
Characteristics of polysilicon oxides combining N2O nitridation and CMP processes
(2000-08-01)
Lei, TF
;
Chen, JH
;
Wang, MF
;
Chao, TS
;
電子工程學系及電子研究所
This paper present a high-quality polysilicon oxide combining N2O nitridation and chemical mechanical polishing (CMP) processes. Experimental results indicate that polyoxide grown on the CMP sample exhibits a lower leakage current, higher dielectric breakdown field, higher electron barrier height, less electron trapping rate, higher charge-to-breakdown (Q(bd)), and lower density of trapping charge than those of non-CMP samples. In addition, the CMP process enhances nitrogen incorporation at the interface by the N2O nitridation, ultimately improving the polyoxide quality, Moreover, the CMP process smooths the surface of polysilicon and this planar surface reduces the out-diffusion of the phosphorous during thermal oxidation.
Detection of the defects induced by boron high-energy ion implantation of silicon
(2000-08-01)
Hsu, WC
;
Chen, MC
;
Liang, MS
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A preferential chemical etching method was used to investigate the secondary defects induced in silicon by high-energy boron ion implantation followed by a rapid thermal anneal at 1000 degrees C for 30 s in N-2 ambient. The dislocation defects in silicon can be clearly delineated by the etchant of CrO3/HF mixing solution. Moreover, a band of striation corresponding To the region of dislocation defects can be observed from the cross-sectional view micrographs of scanning electron microscopy. For the high-energy boron ion implantation at a dose of 3 x 10(14) cm(-2) and energies of 0.5 to 2 MeV studied in this worst, the defect density is estimated to be in the order of 6 x 10(6) cm(-2). Furthermore, we found a close correlation between the depth profiles of the observed etching pits and that of the implanration-induced damage. (C) 2000 The Electrochemical Society. S0013-4651(00)01-011-9. All rights reserved.
Laser- and electric-field-induced local refraction index change in a nematic liquid crystal film
(2000-08-01)
Wu, JJ
;
Chen, SH
;
Fan, JY
;
光電工程學系
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Department of Photonics
We study the Ar+ laser- and electric-field-induced local refraction index change in a planar-parallel-aligned nematic liquid crystal (NLC) film. The laser that is normally incident on the film is strong enough to induce a spatial nonuniformity of the molecular reorientation. The experimental results show that the change of the refraction index of the NLC film is always less than that calculated by the theory in current usage. This is because of the finite beam size effect which is different from the infinite plane wave assumption in the current theory. In this paper, we report some interesting phenomena which result from the finite beam size effect especially near the occurrence of the Fredericksz transition. The experimental results are compared to the theoretical calculations.
Reliability of passivated P-type polycrystalline silicon thin film transistors
(2000-08-01)
Peng, DZ
;
Shin, PS
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Chang, TC
;
Chang, CY
;
電子工程學系及電子研究所
We have used NH3, N2O and N-2 to passivate the traps in the grain boundaries of the p-type polycrystalline silicon thin film transistors (p-type poly-Si TFTs). Two different stress conditions, drain voltage V-d of -15V and -30V, have been applied to the poly-Si TFTs respectively while the gate voltage V-g were kept at -15V for both conditions and the stress time were 10 minutes at room temperature for all samples. The comparisons of I-V characteristics after stress with and without plasma passivations have been made, and the results indicated that the reliability will become worse for poly-Si TFTs after plasma passivations. (C) 2000 Elsevier Science Ltd. All rights reserved.
Internet addiction, usage, gratification, and pleasure experience: the Taiwan college students' case
(2000-08-01)
Chou, C
;
Hsiao, MC
;
傳播研究所
;
Institute of Communication Studies
This study explores Internet addiction among some of the Taiwan's college students. Also covered are a discussion of the Internet as a form of addiction, and related literature on this issue. This study used the Uses and Gratifications theory and the Play theory in mass communication. Nine hundred and ten valid surveys were collected from 12 universities and colleges around Taiwan. The results indicated that Internet addiction does exist among some of Taiwan's college students. In particular, 54 students were identified as Internet addicts, It was found that Internet addicts spent almost triple the number of hours connected to the Internet as compare to non-addicts, and spent significantly more time on BBSs, the WWW, e-mail and games than non-addicts. The addict group found the Internet entertaining, interesting, interactive, and satisfactory. The addict group rated Internet impacts on their studies and daily life routines significantly more negatively than the non-addict group. The study also found that the most powerful predictor of Internet addiction is the communication pleasure score, followed by BBS use hours, sex, satisfaction score, and e-mail-use hours. (C) 2000 Elsevier Science Ltd. All rights reserved.
Dimensional effects on the reliability of polycrystalline silicon thin-film transistors
(2000-08-01)
Zan, HW
;
Shih, PS
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Chang, TC
;
Chang, CY
;
電子工程學系及電子研究所
We found that for unpassivated short-channel TFTs, hot carrier stress-induced degradation phenomena are different with various channel geometries. For device with a wide channel width, the threshold voltage is increased while the subthreshold swing is almost unchanged. The stress-induced oxide-trapped charges are responsible for the degradation. For others with narrow channel widths after stress, on the contrary, the subthreshold swing and I-min are increased, the trap density is greatly increased and the trap-enhanced kink effect is also observed. This is due to the generation of stress-induced grain boundary traps near the drain side. Additionally, the stress-induced degradations of passivated TFTs with various geometries are identical. The increased defect density dominates the mechanism since the hot-carrier stress tends to break the passivated SI-H bonds. (C) 2000 Elsevier Science Ltd. All rights reserved.
Identification of general fuzzy measures by genetic algorithms based on partial information
(2000-08-01)
Chen, TY
;
Wang, JC
;
Tzeng, GH
;
管理學院
;
College of Management
This study develops an identification procedure for general fuzzy measures using genetic algorithms, In view of the difficulty in data collection in practice, the amount of input data is simplified through a sampling procedure concerning attribute subsets, and the corresponding detail design is adapted to the partial information acquired by the procedure. A specially designed genetic algorithm is proposed for better identification, including the development of the initialization procedure, fitness function, and three genetic operations. To show the applicability of the proposed method, this study simulates a set of experimental data that are representative of several typical classes. The experimental analysis indicates that using genetic algorithms to determine general fuzzy measures can obtain satisfactory results under the framework of partial information.
Anomalous phosphorus cracker temperature-dependent photoluminescence spectra of InGaP grown by solid source molecular beam epitaxy
(2000-08-01)
Cheng, YC
;
Tai, KC
;
Chou, ST
;
光電工程學系
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Department of Photonics
InGaP grown by solid source molecular beam epitaxy showed lower effective band-gap energy with increasing phosphorus cracker temperature. Anomalous photoluminescence (PL) spectra also indicated that a weaker ordering effect was initiated when the cracker temperature was higher. Since the variation of cracker temperature mainly changed the P-2/P-4 ratio, we believe that the more chemically reactive P-2 incorporates more In into the epilayer. Therefore, InGaP grown under a more Pt-rich condition has a higher In content which results in the lower band-gap energy instead of having an ordering effect.
Highly selective GaAs/Al0.2Ga0.8As wet etch process for the gate recess of low-voltage-power pseudomorphic high-electron-mobility transistor
(2000-08-01)
Chang, HC
;
Chang, EY
;
Chung, CC
;
Kuo, CT
;
材料科學與工程學系
A selective wet etch process for the gate recess of the GaAs power pseudomorphic high-electron-mobility transistors (pHEMT's) was developed. The power pHEMT's used in this study were epitaxially grown power Al0.2Ga0.8As/In0.2Ga0.8As pHEMT's with a 250 Angstrom GaAs cap layer and a 300 Angstrom Al0.2Ga0.8As electron-donating layer. The electron-donating layer was used as the etch-stop layer for the gate recess. A selectivity of 3400 : 1 was achieved for GaAs/Al0.2Ga0.8As layers using citric acid/tripotassium citrate/hydrogen peroxide etching solutions in this study. This is the highest selectivity for GaAs/AlxGa1-xAs selective etching reported so far. The pHEMT's processed using this selective etching demonstrated good device power performance, and the wet recess process did not cause any contamination or damage to the device. The test data indicates that this selective etch process can be of practical use for forming the gate recess of the power pHEMT's with good device performance and excellent electrical uniformity.
Design of finite-word-length FIR filters with least-squares error
(2000-08-01)
Kao, YA
;
Chen, SG
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper proposes a new algorithm for designing finite word length linear-phase FIR filters. The new algorithm produces finite-precision least-squares error (LSE) solutions with much reduced search time than the brute-force full search algorithm. It is different from the full search algorithm that tries all possible combinations directly. The new algorithm utilizes geometric properties of a hyper-space to pinpoint potential solutions in a much more restricted way. Accordingly, a much smaller search space is generated. (C) 2000 Elsevier Science B.V. All rights reserved.
On the isomorphism between cyclic-cubes and wrapped butterfly networks
(2000-08-01)
Hung, CN
;
Wang, JJ
;
Sung, TY
;
Hsu, LH
;
資訊工程學系
We show that the cyclic-cubes defined by Ada W.C. Fu and S.C. Chau [1] are isomorphic to k-ary wrapped butterfly networks.
Design and analysis of an asymmetrically fed insulated coaxial slot antenna with enhanced tip-heating performance
(2000-08-01)
Wu, LK
;
Su, DWF
;
傳播研究所
;
Institute of Communication Studies
In this paper, a novel use of an asymmetrically fed insulated coaxial slot antenna (ICSA) type of applicator for interstitial microwave hyperthermia that simultaneously exhibits good impedance matching and enhanced tip-heating performances is presented. Theoretical analysis reveals that by making the distal arm much shorter than the other arm of the antenna, charge densities distributed over the distal arm of the antenna increase significantly. This, in turn, can result in the-radial electric-field component becoming the dominant contributor to the specific absorption rate (SAR) over the distal arm side of the heating region and, therefore, the achievement of enhanced tip-heating performance, With the length of the longer arm chosen to be slightly longer than a quarter-wavelength, good impedance matching and enhanced tip-heating performances are achieved when the length of the shorter distal arm is reduced to no more than 25% of that of the longer arm, Good agreements observed between theoretical and measured SAR patterns for two ICSA's designed for operation at 915 and 433 MHz, respectively, confirm the validity of the design method.
Plasma-process-induced damage in sputtered TiN metal-gate capacitors with ultrathin nitrided oxides
(2000-08-01)
Chen, CC
;
Lin, HC
;
Chang, CY
;
Chao, TS
;
Huang, TY
A comprehensive study on plasma-process-induced damage (P21D) in sputtered TiN metal-gated devices with 4 nm N2O-nitrided oxide was performed. We found that the TiN metal-gated devices exhibit a significant 8 Angstrom reduction in the effective oxide thickness, due to physical damage caused by sputtering and/or oxide consumption during the postannealing step. We also found that the postdeposition rapid thermal annealing (RTA) temperature affects both the flat-band voltage (V-fb) and the interface state density (Di,). Furthermore, degradation in the gate-oxide integrity caused by severe charging damage by the additional plasma processes in the TiN metal gate process flow was also observed. The P2ID leads to significant degradation in the charge-to-breakdown and a gate leakage current increase, even for the genuinely robust nitrided oxide used in this study. Finally, Nz plasma posttreatment was proposed as an effective method for suppressing the gate leakage current.