Browsing by Issue Date, starting with "1998-08-01"

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A novel structural design for force/torque fingertip sensors
(1998-08-01)
Chang, YH
;
Huang, YC
;
Liu, YP
;
Tsay, SM
;
電子工程學系及電子研究所
This work presents a novel structural design of force/torque fingertip sensors for sensing planar forces. The resolution can be increased by reducing the condition number of the calibration matrix and the sensitivity can be enhanced by placing strain gauges at specified positions. Moreover, the interaction from off-axis loads is intrinsically negligible in our design. A relatively simple and accurate calibration method for performance evaluation is introduced. Some experimental results are presented to demonstrate the capability of the proposed design.
Texture classification using fuzzy uncertainty texture spectrum
(1998-08-01)
Lee, YG
;
Lee, JH
;
Hsueh, YC
;
資訊工程學系
;
Department of Computer Science
A new method using fuzzy uncertainty, which measures the uncertainty of the uniform surface in an image, is proposed for texture analysis. A grey-scale image can be transformed into a fuzzy image by the uncertainty definition. The distribution of the membership in a measured fuzzy image, denoted by the fuzzy uncertainty texture spectrum (FUTS), is used as the texture feature for texture analysis. To evaluate the performance of the proposed method, supervised texture classification and rotated texture classification are applied. Experimental results reveal high-accuracy classification rates and show that the proposed method is a good tool for texture analysis. (C) 1998 Elsevier Science B.V. All rights reserved.
Design of the coupling schemes for the AC-3 coder in stereo coding
(1998-08-01)
Liu, CM
;
Lee, WC
;
Juang, SY
;
資訊工程學系
;
Department of Computer Science
When applying the Dolby AC-3 coder for the stereo music compression, the coupling scheme that combines the two channels stereo audio signals in high frequency into one channel is the key technology for the Dolby AC-3 to achieve the bit rates lower than 96x2 kbits/sec while preserving high stereo audio quality. This paper proposes four coupling methods for the AC-3 encoder. These four methods vary with the complexity and performance. These four methods are compared through both subjective and objective tests. These four coupling methods are also combined with the dithering scheme and examined through subjective and objective tests. The result shows that the dithering scheme can effectively ease the coupling artifacts and enhance the audio quality.
Image contrast enhancement based on a histogram transformation of local standard deviation
(1998-08-01)
Chang, DC
;
Wu, WR
;
電信工程研究所
;
Institute of Communications Engineering
The adaptive contrast enhancement (ACE) algorithm, which uses contrast gains (CG's) to adjust the high-frequency components of images, is a well-known technique for medical image processing. Conventionally, the CG is either a constant or inversely proportional to the local standard deviation (LSD), However, it is known that conventional approaches entail noise overenhancement and ringing artifacts, In this paper, we present a new ACE algorithm that eliminates these problems. First, a mathematical model for the LSD distribution is proposed by extending Hunt's image model. Then, the CG is formulated as a function of the LSD. The function, which is nonlinear, is determined by the transformation between the LSD histogram and a desired LSD distribution. Using our formulation, it can be shown that conventional ACE's use linear functions to compute the new CG's, It is the proposed nonlinear function that produces an adequate CG resulting in little noise overenhancement and fewer ringing artifacts. Finally, simulations using some X-ray images are provided to demonstrate the effectiveness of our new algorithm.
Multi-objective machine-part cell formation through parallel simulated annealing
(1998-08-01)
Su, CT
;
Hsu, CM
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Group technology (GT) is a manufacturing philosophy which identifies and exploits the similarity of parts and processes in design and manufacturing. A specific application of GT is cellular manufacturing (CM). The first step in the preliminary stage of cellular manufacturing system (CMS) design is cell formation, generally known as a machine-part cell formation (MPCF) or a machine-component grouping (MCG) problem. Simulated annealing (SA) is not only a highly effective and general random search method to obtain near-global optimal solutions for optimization problems, but also quite appropriate for the MPCF problem which is an NP complete, complex problem. In this study, we introduce modified SA with the merits of a genetic algorithm (GA), call parallel SA (PSA), and propose a PSA-based procedure to solve the MPCF problem. More specifically, this study aims to minimize (1) total cost which includes intercell and intracell part transportation cost and machine investment cost, (2) intracell machine loading unbalance and (3) intercell machine loading unbalance under many realistic considerations. The illustrative example, comparisons and analysis demonstrate the effectiveness of this procedure. The proposed procedure is extremely adaptive, flexible, efficient and can be used to solve real MPCF problems in factories by providing a robust manufacturing cell formation in a short execution time.
Performance evaluation of an API Aerosizer (TM)
(1998-08-01)
Tsai, CJ
;
Chein, HM
;
Chang, ST
;
Kuo, JY
;
環境工程研究所
A numerical method was developed to simulate the compressible flow field and particle trajectory in an API Aerosizer(TM). Experimental particle time-of-flights (tau(TOF)) data using mono-disperse solid and liquid particles were also obtained. Theoretical particle tau(TOF) results were compared with the present experimental data and those of Cheng er al. (1993, J. Aerosol Sci. 26, 501-514). Good agreement was found for solid particles. The original tau(TOF) calibration for the API Aerosizer(TM) was found to underestimate measured tau(TOF) mainly because of the assumption of one-dimensional flow in the nozzle, and incorrect use of the particle drag coefficient in the supersonic flow field. Effects of decreasing ambient pressure and increasing particle density on increasing tau(TOF) were found to be important. (C) 1998 Elsevier Science Ltd. All rights reserved.
Video data indexing by 2D C-trees
(1998-08-01)
Hsu, FJ
;
Lee, SY
;
Lin, BS
;
資訊工程學系
;
Department of Computer Science
Video data contains a large amount of spatial and temporal information. The changes of video frames are quite useful for motion analysis and cannot be provided by other media easily. Chang et al: had proposed an effective 2D string approach for spatial indexing of image data. In this paper, we extend this iconic approach and apply it to video data indexing. We propose 2D C-trees to represent the spatial content within individual frames. A video sequence can then be represented and indexed by a temporal set or an ordering set of 2D C-trees. The similarity retrieval of video matching problem becomes the problem of video sequence matching by computing the similarity, or the minimum cost of matched frames. We present three schemes, full-sequence matching, segment matching and subsequence matching, for video information retrieval. The matching schemes can be modified and extended to approximate sequence matching by computing the partial distance for providing a comprehensive retrieval of video data. A prototype video information system is also developed to validate the effectiveness of video data indexing by 2D C-trees. (C) 1998 Academic Press.
The recognition of double Euler trails in series-parallel networks
(1998-08-01)
Ho, TY
;
Sung, TY
;
Hsu, LH
;
Tsai, CH
;
Hwang, JY
Given a series-parallel network (network, for short) N,its dual network N' is given by interchanging the series connection and the parallel connection of network N. We usually use a series-parallel graph to represent a network Let G[N] and G[N'] be graph representations of N and N', respectively. A sequence of edges e(1), e(2),...,e(k) is said to form a common trail on (G[N],G[N']) if it is a trail on both G[N] and G[N']. If a common trail covers all of the edges in G[N] and G[N'], it is called a double Euler trail. However, there are many different graph representations for a network. We say that a network N has a double Euler trail (DET) if there is a common Euler trail for some G[N] and some G[N']. Finding a DET in a network is essential for optimizing the layout area of a complementary CMOS functional cell. Maziasz and Hayes (IEEE Trans. Computer-Aided Design 9 (1990), 708-719) gave a linear time algorithm for solving the layout problem in fixed G[N] and G[N'] and an exponential algorithm for finding the optimal cover in a network without fixing graph representations. In this paper, we study properties of subnetworks of a DET network. According to these properties, we propose an algorithm that automatically generates the rules for composition of trail cover classes. On the basis of these rules, a linear time algorithm for recognizing DET networks is presented. Furthermore, we also give a necessary and sufficient condition for the existence of a double Euler circuit in a network. (C) 1998 Academic Press.
Global derivation of marine gravity anomalies from Seasat, Geosat, ERS-1 and TOPEX/POSEIDON altimeter data
(1998-08-01)
Hwang, C
;
Kao, EC
;
Parsons, B
;
土木工程學系
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Department of Civil Engineering
Marine gravity anomalies over the area 82 degrees S to 82 degrees N and 0 degrees E to 360 degrees E on a 2' x 2' grid have been derived from Seasat, Geosat, ERS-1 and TOPEX/POSEIDON altimeter data. The inverse Vening Meinesz formula with a 1-D FFT method was used to compute gravity anomalies from gridded north-south and west-east geoid gradients, in a remove-restore procedure with the EGM96 gravity model as the reference field. This paper presents a new gridding technique and an altimeter data management system that help to extract date efficiently. In the 12 areas where ship-measured gravity and satellite-derived gravity were compared, rms agreements of 5-14 mgal were obtained. Special discussions of the gravity anomalies over selected inland seas, the Arctic, Antarctica and coastal waters are presented. The derived gravity anomalies show detailed tectonic structures of the world ocean. The global data set will be continuously updated with more altimeter data included in the derivation.
Subband Kalman filtering for speech enhancement
(1998-08-01)
Wu, WR
;
Chen, PC
;
電信工程研究所
;
Institute of Communications Engineering
Kalman filtering is an effective speech-enhancement technique, in which speech signals are usually modeled as autoregressive (AR) processes and represented in the state-space domain. Since AR coefficients identification and Kalman filtering require extensive computations, real-time implementation of this approach is difficult. This paper proposes a simple and practical scheme that overcomes these obstacles. Speech signals are first decomposed into subbands. Subband speech signals are then modeled as low-order AR processes, such that low-order Kalman filters can he applied. Enhanced fullband speech signals are finally obtained by combining the enhanced subband speech signals. To identify AR coefficients, prediction-error filters adapted by the LMS algorithm are applied. Due to noisy inputs, the LMS algorithm converges to biased solutions. The performance of the Kalman filter with biased parameters is analyzed, It is shown that accurate estimates of AR coefficients are not required when the driving-noise variance is properly estimated. New methods for making such estimates are proposed. Thus, we can tolerate biased AR coefficients and take advantage of the LMS algorithm's simple structure. Simulation results show that speech enhancement in the subband domain not only greatly reduces the computational complexity, but also achieves better performance compared to that in the fullband domain.
Preparation and electronic properties of YBa2Cu3Ox films with controlled oxygen stoichiometries
(1998-08-01)
Wu, KH
;
Hsieh, MC
;
Chen, SP
;
Chao, SC
;
Juang, JY
We describe a novel technique capable of controlling the oxygen content of YBa2Cu3Ox (YBCO) films in a precise and reversible manner. The temperature dependence of resistivity and the distinct two-plateau behavior in critical temperature T-CO versus oxygen content plot of these films are consistent with those observed in the bulk and single crystals of YBCO. The O 1s and Cu 2p absorption spectra of these films were measured by polarization-dependent X-ray absorption spectroscopy (XAS). The intensity variations of the pre-edge peaks as a function of oxygen content are discussed. We also used these films to systematically study the electron-phonon coupling strength and the position of Fermi level by using a femtosecond pump-probe technique. A clear sign-reversal of the transient reflectivity, which was consistently explained by the thermomodulation model, was observed. Both of these optical measurements support the idea that the electronic structure of YBCO cuprates is based on the charge transfer model with hybridization between the Cu and O sites.
Bit allocation method for AC-3 encoder
(1998-08-01)
Liu, CM
;
Lee, SW
;
Lee, WC
;
資訊工程學系
;
Department of Computer Science
Dolby AC-3 is an audio coder selected in the United State high definition television (HDTV) standards and widely adopted for the audio codec in DVD films. For audio coder, the complexity of the audio encoders is always higher than that of the decoders. A main module leading to the higher complexity is the bit allocation process. The objective of the bit allocation is to allocate restricted bits to encoded information. Since that AC-3 coder has adopted a floating point representation which the magnitude of each spectral line is represented with an exponent and a mantissa, the bit allocation process not only has to decide the suitable quantization method for the mantissa similar to the process in other coding standards such as MPEG1, but also the exponent strategies and hence the parameters in psychoacoustic models. This coding process has been referred to as a hybrid coding [5] and has led to immense complexity for an encoder. This paper proposes an efficient method for the bit allocation process.
Automatically integrating multiple rule sets in a distributed-knowledge environment
(1998-08-01)
Wang, CH
;
Hong, TP
;
Tseng, SS
;
Liao, CM
;
資訊工程學系
In this paper, an actual knowledge application is made by means of evolution paradigms in terms of knowledge acquisition. rin automatic knowledge integration approach in a distributed-knowledge environment is thus proposed to integrate multiple rule sets into a single effective rule set. The proposed approach consists of two phases: knowledge encoding and knowledge integration. In the encoding phase, each knowledge input is translated and expressed as a rule set, then encoded as a bit string. The combined bit strings from multiple knowledge inputs form an initial knowledge population, which is then ready for integration. In the knowledge integration phase, a genetic search technique generates an optimal or nearly optimal rule set from these initial knowledge-input strings. Finally, experimental results from diagnosis of brain tumors show that the rule set derived by the proposed approach is much more accurate than each initial rule set.
An integrated method in wavelet-based image compression
(1998-08-01)
Hsu, HH
;
Hu, YQ
;
Wu, BF
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, we propose an integrated image compression method, which contains the discrete wavelet transform, scalar quantization and some lossless codings, to gain higher compression ratios while maintaining the image fidelity. The discrete wavelet transform has the properties of entropy reduction and energy concentration in high frequency subimages. An innovative approach, called revised rein-length coding, is proposed to improve the compression performance. The idea of this approach is to represent the appearance of symbols of the run-length cone in exponential expression for saving the storage in bits. The differential pulse code modulation is used to reduce the entropy of the lowest frequency subimage of the discrete wavelet transform and to achieve high compression effects losslessly. (C) 1998 The Franklin Institute. Published by Elsevier Science Ltd.
Miscibility and transesterification in blends of liquid crystalline copolyesters and polyarylate
(1998-08-01)
Tyan, HL
;
Wei, KH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Blends of poly(oxybenzoate-p-ethylene terephthalate) (POB-PET) and polyarylate were confirmed to be a partially miscible system by differential scanning calorimetry. When 60/40 POB-PET/PAr blend was annealed at high temperature (above 270 degrees C) for several minutes, the ester-ester interchange( transesterification)in the blend took place immediately, as evidenced by Fourier Transformed infrared analyses. The analysis of the blend annealed at 290 degrees C by H-1-C-13 nuclear magnetic resonance disclosed that there were four new diads appearing in 15 min and an additional one produced in 60 min during the heat treatment. The miscibility between POB-PET and polyarylate increased with the mol concentration of these new diads judging from differential scanning calorimetry. The evolution of the concentration of the diad ethylene glycol-isophthalate during the annealing can be described by a second-order reaction. The activation energy of forming the diad ethylene glycol-isophthalate was 26.5 kcal/mol, and the preexponential factor for the transesterification reaction is 3.7 x 10(8) min(-1). (C) 1998 John Wiley & Sons, Inc.
High-performance CMOS buffered gate modulation input (BGMI) readout circuits for IR FPA
(1998-08-01)
Hsieh, CC
;
Wu, CY
;
Sun, TP
;
Jih, FW
;
Cherng, YT
A new CMOS current readout structure for the infrared (IR) focal-plane-array (FPA), called the buffered gate modulation input (BGMI) circuit, is proposed in this paper. Using the technique of unbalanced current mirror, the new BGMI circuit can achieve high charge sensitivity with adaptive current gain control and good immunity from threshold-voltage variations. Moreover, the readout dynamic range can be significantly increased by using the threshold-voltage-independent current-mode background suppression technique. To further improve the readout performance, switch current integration techniques, shared-buffer biasing technique, and dynamic charging output stage with the correlated double sampling circuit are also incorporated into the BGMI circuit, An experimental 128 x 128 BGMI readout chip has been designed and fabricated in 0.8 mu m double-poly-double-metal (DPDM) n-well CMOS technology, The measurement results of the fabricated readout chip under 77K and 5 V supply voltage have successfully verified both readout function and performance improvement. The fabricated chip has the maximum charge capacity of 9.5 x 10(7) electrons, the transimpedance of 2.5 x 10(9) Omega at 10 nA background current, and the active power dissipation of 40 mW, The uniformity of background suppression currents can be as high as 99%. Thus, high injection efficiency, high charge sensitivity, large dynamic range, large storage capacity, and low noise can be achieved in the BGMI circuit with the pixel size of 50 x 50 mu m(2), These advantageous characteristics make the BGMI circuit suitable for various IR FPA readout applications with a wide range of background currents.
International development of Taiwan's information industry: An empirical study on human resource strategy of overseas subsidiaries
(1998-08-01)
Liu, SJ
;
Huang, TL
;
Chen, QH
;
科技管理研究所
;
Institute of Management of Technology
Since the 1980's, personal computers (PC's) and semiconductors have emerged as Taiwan's two leading high-technology industries. As of the 1990's, Taiwan has attained third place among PC manufacturers, and PC's and peripherals have become Taiwan's largest export products. Entrepreneurial small businesses, fierce competition in the local economy, and efficient industrial networking characterize Taiwan's PC industry, with flexible production and shortened time to market. This study investigates the human resource strategies of overseas subsidiaries of Taiwan's information enterprises, primarily the PC production industry. Gaining the comparative advantages of production from foreign resources of labor, materials, and key components are among the prime concerns. Direct access to foreign markets and marketing information constitute that more offices be established abroad. In general, internationalization of Taiwan's PC industry partakes more of a headquarters-controlled style of global management, Overseas subsidiaries are essentially extensions of Taiwan- and manufacturing-based PC enterprises. This study integrates theoretical frameworks of the eclectic paradigm and the integration-responsiveness models and explores four strategic patterns of human resource on the basis of two dimensions: consistency with parent-company policy and local responsiveness of a foreign subsidiary, Statistical measures as well as qualitative analysis reveal that both domestic corporate characteristics and overseas local features significantly influence management policy, While Taiwanese information enterprises are increasingly moving toward global expansion, the majority are at a learning stage in international business development. Internalization of Taiwan's PC industry primarily depends on the manufacturing capability of local headquarters and joint ventures with foreign companies. The manufacturing-based PC industry in Taiwan is moving toward key component production and brand marketing while integrating global resources to compete against established transnational corporations.
Modelling of a polarization-division multiplexing soliton transmission system
(1998-08-01)
Chen, CF
;
Chi, S
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光電工程學系
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Department of Photonics
We have simulated numerically a polarization-division multiplexing soliton transmission system by using propagation equations with and without the third-order dispersion and Raman shift terms, respectively. it is found that the Raman shift terms can reduce the soliton interactions and hence the allowed transmission distance increases.
Computer-aided manufacturing of spiral bevel and hypoid gears with minimum surface-deviation
(1998-08-01)
Lin, CY
;
Tsay, CB
;
Fong, ZH
;
機械工程學系
;
Department of Mechanical Engineering
The linear regression method to minimize the deviations of a real cut gear-tooth-surface is investigated in this paper. Based on the Gleason hypoid gear generator, a mathematical model of the tooth surface is proposed. Applying the proposed mathematical model, the sensitivities of tooth surface due to the variations of machine-tool setting are also investigated. The corrective machine-tool settings, calculated by using the sensitivity matrix and the linear regression method, are used to minimize the tooth-surface deviations. The minimization problem was solved by using the singular value decomposition (SVD) method. The result of this paper can improve the conventional development process and be also applied to different manufacturing machines and methods. Two examples are presented to demonstrate the proposed methodology. (C) 1998 Elsevier Science Ltd. All rights reserved.
Using parallel line information for vision-based landmark location estimation and an application to automatic helicopter landing
(1998-08-01)
Yang, ZF
;
Tsai, WH
;
資訊工程學系
;
Department of Computer Science
An approach to landmark location estimation by computer vision techniques is proposed. The objective is to derive the position and the orientation of the landmark with respect to the vehicle by a single image. Such information is necessary for automatic vehicle navigation. This approach requires lower hardware cost and simple computation. The vanishing points of the parallel lines on the landmark are used to detect the landmark orientation. The detected vanishing points are used to derive the relative orientation between the landmark and the camera, which is then utilized to compute the landmark orientation with respect to the vehicle. The size of the landmark is used to determine the landmark position. Sets of collinear points are extracted from the landmark and their inter-point distances are computed. The positions of the collinear point sets are evaluated and used to determine the landmark position. Landing site location estimation by using the identification marking H on the helicopter landing site for automatic helicopter landing is presented as an application of the proposed approach. Simulations and experiments have been conducted to prove the feasibility of the proposed approach. (C) 1998 Elsevier Science Ltd. All rights reserved.