Browsing by Issue Date, starting with "1999-07-01"

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Synthesis and characterization of side-chain liquid crystalline polyoxetanes containing 4-(alkanyloxy)phenyl 4-pentylbenzoate side groups
(1999-07-01)
Hsu, CS
;
Lu, YH
;
應用化學系
;
Department of Applied Chemistry
The synthesis and characterization of side-chain liquid-crystalline polyoxetanes containing 4-(alkanyloxy)phenyl 4-pentylbenzoate side groups is presented. Differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction measurements were used to characterize the mesomorphic properties of the polyoxetanes. Those polymers with three to five methylene units in the spacers exhibit the enantiotropic smectic A and a nematic phaser, whereas the polymers with longer spacers (n = 6 or 12) display polymorphism of smectic phases. The polyoxetane backbones are amorphous in nature. No side chain crystallization occurred for any of the polyoxetanes synthesized in this study.
Highly (111) textured titanium nitride layers for sub- quarter-micrometer Al metallization
(1999-07-01)
Wu, WF
;
Lin, CC
;
Huang, CC
;
Lin, HC
;
Chang, TC
Texture improved TiN films were prepared by a two-step deposition process. A thin uncollimated TiN layer is deposited first at low substrate temperature and sputtering power. This layer has poor step coverage and high resistivity, but acts as a crystallographic seed layer for the subsequent collimated TiN layer deposited at high substrate temperature and sputtering power. The TiN layer stack is deposited sequentially without vacuum break. The resulting TiN layer has a low resistivity of 72.25 mu Omega cm, high <111> preferred orientation, and improved bottom coverage in sub-quarter-micrometer contact holes and trenches. (C) 1999 The Electrochemical Society. S1099-0062(99)01-023-8. All rights reserved.
Effects of O-2- and N2O-plasma treatments on properties of plasma-enhanced-chemical-vapor-deposition tetraethylorthosilicate oxide
(1999-07-01)
Chen, YC
;
Yang, MZ
;
Tung, IC
;
Chen, MP
;
Feng, MS
The high quality silicon oxide films were prepared by plasma-enhanced chemical vapor deposition (PECVD) using tetraethylorthosilicate (TEOS)-oxygen based chemistry. The O-2- or N2O-plasma treatments were performed on the as-deposited films as an attempt to improve the properties of the TEOS oxide films. TEOS oxide film deposited at lower pressure had lower Si-OH content, less carbon impurity, and flatter surface, and hence had better electrical properties. Both O-2- and N2O-plasma would decrease the oxygen content of the oxide film, which led the composition of the film to deviate from the stoichiometric SiO2. The O-2-plasma treatment did not show the encouraging effect on the chemical structure and electrical properties of the TEOS oxide films. In contrast, the N2O-plasma treatment could be a promising means to improve the breakdown field and leakage current density of the TEOS oxide films, which was accomplished by the N2O-plasma effect to facilitate the passivation of dangling bonds, linking reaction of Si-OH bonds, nitridation reaction and densification of the amorphous silicon oxide network.
The fleet size and mix vehicle routing problem with time windows
(1999-07-01)
Liu, FH
;
Shen, SY
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
This paper describes several insertion-based savings heuristics for the fleet size and mix vehicle routing problem with time window constraints. A certain number of candidate fleet compositions are recorded in the construction phase, followed by applying a composite improvement scheme on them to enhance the solution quality. Computational results on 168 sample problems are reported. We found that heuristics with the consideration of a sequential route construction parameter yielded very good results. In addition, results on the 20 benchmarking problems for the fleet and mix vehicle routing problem with no time window constraints also demonstrate the effectiveness of our heuristics.
Extended generalized shuffle networks: Sufficient conditions for strictly nonblocking operation
(1999-07-01)
Richards, GW
;
Hwang, FK
;
應用數學系
;
Department of Applied Mathematics
Since Clos gave the first construction of a strictly nonblocking multistage interconnection network, only a few other constructions have been proposed in almost a half-century. In this paper, we introduce a constructive class of networks which utilizes crossbars of virtually any size and for which the sizes can vary from stage to stage. The interconnection between stages is a generalized shuffle pattern. We derive sufficient conditions for strictly nonblocking operation and suggest the potential for wide application of these networks by providing several special case results. (C) 1999 John Wiley & Sons, Inc.
An approach to checking link conflicts in the mapping of uniform dependence algorithms into lower dimensional processor arrays
(1999-07-01)
Ke, JY
;
Tsay, JC
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose an enumeration method to check link conflicts in the mapping of n-dimensional uniform dependence algorithms with arbitrary convex index sets into k-dimensianal processor arrays. Previous methods on checking the link conflicts had to examine either the whole index set or the I/O spaces whose size are O(N-2n) or O(Nn-1), respectively, where hr is the problem size of the n-dimensional uniform dependence algorithm. In our approach, checking the link conflicts is done by enumerating integer solutions of a mixed integer linear program. In order to enumerate integer solutions efficiently, a representation of the integer solutions is devised so that the size of the space enumerated is O((2N)(n-k)). Thus, our approach to checking link conflicts has better performance than previous methods, especially for larger k. For the special case k = n - 2, we show that link conflicts can he checked by solving two linear programs in one variable.
Gauge independent effective potential and the Higgs boson mass bound
(1999-07-01)
Lin, GL
;
Chyi, TK
;
物理研究所
;
Institute of Physics
We introduce the Vilkovisky-DeWitt formalism for deriving the lower bound of the Higgs boson mass. We illustrate the formalism with a simplified version of the standard electroweak model, where all charged boson fields as well as the bottom-quark field are disregarded. The effective potential obtained in this approach is gauge independent. We derive from the effective potential the mass bound of the Higgs boson. The result is compared to its counterpart obtained from the ordinary effective potential. [S0556-2821(99)06211-6].
Bioconversion with whole cell penicillin acylase in aqueous two-phase systems
(1999-07-01)
Liao, LC
;
Ho, CS
;
Wu, WT
;
生物科技學系
;
Department of Biological Science and Technology
The deacylation of Pen G was carried out by using recombinant E. coli in an aqueous two-phase system consisting of polyethylene glycol and potassium phosphate solution, which partitions the cells to the bottom phase and the products to the top phase. Bioconversion and product separation were carried out in the same reactor. Repeated batch conversion was employed ten times and enzymic activity showed only a slight decline. When pure enzyme was used for bioconversion in an aqueous two-phase system, the decline was fast and bioconversion using whole cell penicillin acylase was better than that obtained using the pure acylase. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.
An efficient probabilistic dynamic multicast routing in ATM networks
(1999-07-01)
Wang, KC
;
Chen, JH
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose a dynamic multicast routing algorithm based on probability for multimedia communications in an asynchronous transfer mode (ATM) network environment. For multimedia communications, we not only aim to arrange a transmission path with the minimal cost from a source node to each destination node, but also consider the dynamic multicast situation with node joining/leaving. To meet the above requirements, we develop a new method based on the relative probability of each node being truncated from the multicast connection tree, such that we can arrange a better path for a new joining node in such a way as to reduce the impact of leaving requests caused by other nodes in the multicast connection tree. The main contribution of this paper is a new and efficient dynamic multicast routing algorithm for multimedia communications which keeps the whole multicast connection tree near optimal in terms of cost inefficiency and guarantees that the transmission delay will be less than the preset bounded end-to-end delay. Simulation results show that under various sizes of networks and requests, the cost inefficiency of the multicast connection tree constructed by our approach is less than those of the trees constructed by the greedy algorithm and the weighted greedy algorithm, respectively.
Effects of rapid thermal annealing on cobalt silicided p(+) poly-Si gates fabricated by BF2+ implantation into bilayered CoSi/a-Si films
(1999-07-01)
Lai, WK
;
Liu, HW
;
Juang, MH
;
Cheng, HC
;
電子工程學系及電子研究所
The cobalt polycide gate formed by implanting BF2+ ions into the bilayered CoSi/a-Si films and the subsequent rapid thermal anneal has been studied. The resulting gate oxide integrity is characterized with respect to various silicide thicknesses and implantation energies. Significant degradation in gate oxide integrity and Aat-band voltage shift were found with increasing silicide thickness and annealing temperature, especially for the thicker CoSi2 films, which is attributable to severe boron penetration. Although a thinner silicide can achieve excellent gate dielectric reliability, it will lead to poor high-temperature thermal stability. Moreover, shallower implantation depth and lower annealing temperature, which sustain less boron penetration, would cause the poly-Si gate depletion effects. Therefore, appropriate conditions, which comprise the CoSi2 thickness, the implantation energy, and the annealing temperature, should be employed to optimize the device performance while retaining the thin dielectric reliability.
Local stability criterion for a gravitating disk of stars
(1999-07-01)
Griv, E
;
Rosenstein, B
;
Gedalin, M
;
Eichler, D
;
電子物理學系
Computer N-body experiments are described which test the validities of the original Toomre's ( 1964) criterion and of a generalized criterion for local stability of Jeans-type perturbations in a self-gravitating, infinitesimally thin, and practically collisionless disk of stars. The fact that the nonaxisymmetric perturbations in the differentially rotating system are more unstable than the axisymmetric ones is taken into account in this generalized criterion. It is shown that for differentially rotating disks, the generalized criterion works as well as Toomre's ordinary criterion does for rigidly rotating ones. A modest discrepancy is observed between the analytical stability criteria and the numerical results. We tentatively attribute this to the shortcomings of the asymptotic density wave theory and possibly additional ones introduced by approximations in the local numerical code employed here. In addition, the linear stability theory of small oscillations of a disk of stars is reexamined by using the method of particle orbit theory. This representation gives new insight into the problem of gravitating disk stability. Certain applications of the theory and the N-body simulations to actual disk-shaped spiral galaxies are explored as well.
Magnetic domain pinning in patterned perpendicular magnetic anisotropy material
(1999-07-01)
Wu, TH
;
Wu, JC
;
Chen, BM
;
Shieh, HPD
;
光電工程學系
A method for pinning magnetic domains with prescribed shapes has been developed for the magneto-optical thin film material Dy(x)(FeCo)(1-x). The pinning array of holes on the substrate was fabricated using electron beam lithography. The thin film of Dy(x)(FeCo)(1-x) sandwiched between SiN layers was deposited onto a patterned polymethyl methacrylate layer. The pinned domains acquire the shape of the holes, while the sharpness of their boundaries depends on the size of the holes. The stability of the pinned domains is affected by the sample's magnetization. In our experiments, the minimum stable domain size pinned within the hole array was found to be around 50 nm in diameter. (C) 1999 Elsevier Science B.V. All rights reserved.
Investigation on multilayered chemical vapor deposited Ti TiN films as the diffusion barriers in Cu and Al metallization
(1999-07-01)
Hu, JC
;
Chang, TC
;
Chen, LJ
;
Yang, YL
;
Chen, SY
A novel multilayered chemical vapor deposition (CVD) Ti/TiN structure was found to be a more effective diffusion barrier in Cu metallization than TIN alone. The Ti and TIN films were deposited by plasma enhanced CVD and low pressure CVD, respectively. In order to reduce the concentration of chlorine in the films, NH3 plasma posttreatment was applied to multilayered CVD-Ti/TiN films. The resistivity of the film was reduced from 240 to 120 mu Omega cm using NH3 plasma posttreatment. Cu was electroplated on the multilayered CVD-Ti/TiN films. X-ray diffraction patterns showed a small (002) peak and strong (111) peak from the Cu film. The leakage current was kept low during the device application test indicating the Ti/TiN film possessed an enhanced barrier property over the TiN film alone. (C) 1999 American Vacuum Sotiety. [S0734-2101(99)12004-9].
Navigation integration of a mobile robot in dynamic environments
(1999-07-01)
Song, KT
;
Chang, CC
;
電機資訊學士班
;
Undergraduate Honors Program of Electrical Engineering and Computer Science
This article presents a design and experimental study of navigation integration of an intelligent mobile robot in dynamic environments. The proposed integration architecture is based on the virtual-force concept, by which each navigation resource is assumed to exert a virtual force on the robot. The resultant force determines how the robot will move. Reactive behavior and proactive planning can both be handled in a simple and uniform manner using the proposed integration method. A real-time motion predictor is employed to enable the mobile robot to deal in advance with moving obstacles. A grid map is maintained using on-line sensory data for global path planning, and a bidirectional algorithm is proposed for planning the shortest path for the robot by using updated grid-map information. Therefore, the mobile robot has the capacity to both learn and adapt to variations. To implement the whole navigation system efficiently, a blackboard model is used to coordinate the computation on board the vehicle. Simulation and experimental results are presented to verify the proposed design and demonstrate smooth navigation behavior of the intelligent mobile robot in dynamic environments, (C) 1999 John Wiley & Sons, Inc.
A recurrent self-organizing neural fuzzy inference network
(1999-07-01)
Juang, CF
;
Lin, CT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A recurrent self-organizing neural fuzzy inference network (RSONFIN) is proposed in this paper, The RSONFIN is inherently a recurrent multilayered connectionist network for realizing the basic elements and functions of dynamic fuzzy inference, and may he considered to be constructed from a series of dynamic fuzzy rules, The temporal relations embedded in the network are built by adding some feedback connections representing the memory elements to a feedforward neural fuzzy network, Each weight as well as node in the RSONFIN has its own meaning and represents a special element in a fuzzy rule. There are no hidden nodes (i.e., no membership functions and fuzzy rules) initially in the RSONFIN, They are-created on-line via concurrent structure identification (the construction of dynamic fuzzy if-then rules) and parameter identification (the tuning of the free parameters of membership functions). The structure learning together with the parameter learning forms a fast learning algorithm for building a small,yet powerful, dynamic neural fuzzy network Two major characteristics-of the RSONFIN can thus be seen:1) the recurrent property of the RSONFIN makes it suitable for dealing with temporal problems and 2) no predetermination, Like the number of hidden nodes, must be given, since the RSONFIN can find its optimal structure and parameters automatically and quickly, Moreover, to reduce the number of fuzzy rules generated, a flexible input partition method,the aligned clustering-based algorithm, is proposed. Various simulations on temporal problems are done and performance comparisons with some existing recurrent networks are also made, Efficiency of the RSONFIN is verified from these results.
過客
(1999-07-01)
管管
Radiation characteristics of active frequency-scanning leaky-mode antenna arrays
(1999-07-01)
Wang, CJ
;
Jou, CF
;
Wu, JJ
;
Peng, ST
;
傳播研究所
Active frequency-tuning beam-scanning leaky-mode antenna arrays have been demonstrated in this paper. These antennas integrated one or several microstrip leaky-wave antenna elements with a single varactor-tuned HEMT VCO as an active source. Noted that the measured scan angles of the 1x1 and 1x4 antennas were approximately 24 degrees and the scanning range of the 1x2 antenna was 20 degrees. Furthermore, reflected wave due to the open end of each leaky-wave antenna element has been suppressed by the symmetric configuration of this antenna array and the antenna efficiency increases. When comparing with the measured radiation pattern of the single element antenna, we found that the 1x2 and 1x4 antenna arrays can effectively suppress the reflected power by more than 5.5 dB and 10.5 dB, respectively, at 10.2 GHz. The power gain are more than 2 dB and 3.16 dB higher than the single element antenna with a measured EIRP of 18.67 dBm.
Towards a practical visual object-oriented programming environment: Desirable functionalities and their implementation
(1999-07-01)
Hu, CH
;
Wang, FJ
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
The ultimate goal of a programming environment is to help simplify the software development process. For an object-oriented language, a visual (object-oriented) program ming environment (VOOPE) must at least satisfy four essential requirements to meet this goal: interactivity: integration, incrementality, and intelligence. In this study, object-oriented techniques were systematically applied to construct such a VOOPE. On the other hand, some characteristics of object-oriented languages, such as inheritance and polymorphism, may themselves be barriers to understanding, maintaining, and even constructing object-oriented programs. To solve, or at least alleviate, this problem, a language-based editing process has been designed and incorporated into our VOOPE. This process contains two key elements: syntax-directed editing facilities and an in-place editing assistant, which facilitate object-oriented program development by providing useful programming guidance and by reducing the number of potential programming errors. We have so far developed a window-based environment prototype using Visual C++ and the Microsoft Foundation Classes library.
Propagation and reflection of thermal waves in a rectangular plate
(1999-07-01)
Wu, JP
;
Chu, HS
;
機械工程學系
;
Department of Mechanical Engineering
The wave nature of heat propagation in a two-dimensional rectangular plate with an instantaneous thermal disturbance released in an arbitrary position is investigated by solving the hyperbolic heat conduction equation. The exact analytical solutions are developed for the temperature field and heat flux using the Green's function technique to deal with two limiting boundary conditions, the constant wall temperature and the adiabatic condition, around the region. The disturbance gives rise to a severe thermal wave front, which differs completely front that obtained through one-dimensional analysis, traveling through the medium at a finite speed with a sharp peak at the leading edge. The significant findings in these results are that a negative trailer is generated and follows behind the wave front. In addition, the magnitude of the front is significantly attenuated from the side adjacent to the trailer because the increasing area available to it for diffusion, and decays exponentially along its path of travel, since the thermal energy is dissipated in the wake of the moving wave front. The results also reveal that different boundary conditions strongly influence the reflection of a thermal wave front from the exterior surfaces and the reflection and interaction among thermal waves are more complicated than those found through one-dimensional analysis.
Improving GSM call completion by call reestablishment
(1999-07-01)
Lin, PN
;
Lin, YB
;
Jeng, JY
;
資訊工程學系
;
Department of Computer Science
Global system for mobile communications (GSM) call reestablishment service allows a mobile station to resume a call in which the radio link has been temporarily interrupted due to interference or bad signal (which is referred to as an interrupted call). This service increases end user satisfaction and network quality perception. In this paper, we propose analytic models to study the performance for call reestablishment service. Our study indicates that call reestablishment can significantly reduces dropping for interrupted calls.