Browsing by Issue Date, starting with "1992-05-01"

Now showing 1 - 20 of 90714

ADOPTABILITY AND EFFECTIVENESS OF MICROCODE COMPACTION ALGORITHMS IN SUPERSCALAR PROCESSING
(1992-05-01)
SHIAU, YH
;
CHUNG, CP
;
交大名義發表
;
資訊科學與工程研究所
;
National Chiao Tung University
Superscalar processing is a technique to improve uniprocessor performance by exploiting instruction-level parallelism to issue and execute more than one instruction per clock cycle. To achieve high performance, the instruction sequence must be arranged so that the maximum instruction-level parallelism and hence the minimum execution time are achieved. Microcode compaction is an essential task in the compilation of high-level language programs into microprograms. Four algorithms are widely used in microcode compaction: the first-come-first-served algorithm, critical path algorithm, branch and bound algorithm, and list scheduling algorithm. The objective of this research is to study the adaptability and effectiveness, and to modify the four algorithms so that they can be applied to the instruction scheduling in a basic block of superscalar processor systems to minimize the execution time of a program. Experiments are conducted to examine the adaptability and effectiveness of each algorithm.
WHICH LINEAR TRANSFORMATIONS HAVE ISOMORPHIC HYPERINVARIANT SUBSPACE LATTICES
(1992-05-01)
WU, PY
;
交大名義發表
;
應用數學系
;
National Chiao Tung University
;
Department of Applied Mathematics
Let A be a linear transformation on a finite-dimensional complex vector space with the associated algebra Alg A, commutant {A}', and hyperinvariant subspace lattice Hyperlat A. We determine Alg A, {A}' (up to algebra isomorphism), and Hyperlat A (up to lattice isomorphism) in terms of the parameters in the Jordan form of A.
PHYSICAL MODEL FOR CHARACTERIZING AND SIMULATING A FLOTOX EEPROM DEVICE
(1992-05-01)
WU, CY
;
CHEN, CF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A physical model has been developed to analyze the dynamic characteristics of a FLOTOX EEPROM device. The effects of the structural parameters such as the area and thickness of the tunneling-oxide and interpoly-oxide layers are characterized by a coupling ratio to describe the discrete programming or erasing operation. The physical parameters including the electron trapping and positive-charge generation effects are used to describe the endurance and retention operations of an EEPROM device. Computer simulations based on this model have been performed to analyze the operations of an EEPROM device, including the effects of three different programming/erasing input voltage waveforms (pulse, exponential rise and triangular). A method for protecting an EEPROM device from overshooting or undershooting during programming or erasing operation is proposed. Therefore, the proposed model can be used as a computer-aided-design (CAD) tool for device design and an efficient simulation tool for describing the dynamic operation and reliability of an EEPROM device.
THE ROLE OF CEMENTED WC SUBSTRATE MORPHOLOGY ON THE DIAMOND FILM GROWTH AND CRACKING RESISTANCE
(1992-05-01)
HUANG, TH
;
KUO, CT
;
LIN, TS
;
機械工程學系
;
Department of Mechanical Engineering
PHASE-TRANSITION IN AN FE-23.2AL-4.1NI ALLOY
(1992-05-01)
LIU, TF
;
JENG, SC
;
WU, CC
;
機械工程學系
;
材料科學與工程學系
The phase transition in an Fe-23.2 at. pct Al-4.1 at. pct Ni alloy has been investigated by means of transmission electron microscopy. In the as-quenched condition, the microstructure of the alloy is a mixture of (A2 + B2) phases. When the as-quenched alloy is aged at temperatures ranging from 500-degrees-C to 1050-degrees-C, the phase transition sequence is found to be (A2 + B2*) --> (B2 + B2*) --> B2 --> A2, where B2* is also a B2-type phase. It is worthwhile to note that the coexistence of two kinds of ordered B2 phase has not previously been observed by other workers in the Fe-Al-Ni ternary alloy system.
A HARDWARE IMPLEMENTABLE 2-LEVEL PARALLEL COMPUTING ALGORITHM FOR GENERAL MINIMUM-TIME CONTROL
(1992-05-01)
LIN, SY
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
;
Institute of Electrical and Control Engineering
In this paper, we propose a hardware implementable two-level parallel computing algorithm for general minimum-time control. We first discretize and transform the minimum-time control problem for a continuous-time system into a parameter optimization problem which is large dimensional and nonseparable. Then, the proposed two-level algorithm decomposes this parameter optimization problem into a master-slave problem. The master problem can be easily solved by a one-dimensional gradient method, and the slave problem will be solved by the proposed parallel computing method which combines recursive quadratic programming with the dual method. Furthermore, we have proved the convergence of this iterative two-level parallel computing algorithm under some conditions. Based on the VLSI array processor technology, we present a dedicated hardware computing architecture to realize this algorithm. The corresponding time complexity is also analyzed. Finally, several practical problems including the minimum-time orbit transfer problem and the minimum-time robot control problem have been simulated. The results show that the algorithm is well-suited for real-time application of minimum-time control.
SYNTHESIS OF POLE-ZERO ASSIGNMENT CONTROL LAW WITH MINIMUM CONTROL INPUT
(1992-05-01)
TU, MH
;
LIN, CM
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A new method of control system design is developed to simultaneously consider the internal stability, pole assignment, reference signal tracking and control input minimisation. A parametrised design algorithm of the pole-zero assignment control law is derived to achieve the desired goals. The free parameters are used to minimise the L2-norm of the control input signal. Since the requirements of internal stability are satisfied, this design algorithm performs appropriately, even if the plant is unstable and/or is in a nonminimum phase. Examples are given to illustrate the validity of the design algorithm.
THE NOVEL PREPARATION OF P-N-JUNCTION MESA DIODES BY SILICON-WAFER DIRECT BONDING (SDB)
(1992-05-01)
YEH, CF
;
SHYANG, HL
;
電控工程研究所
;
光電工程學系
;
Institute of Electrical and Control Engineering
The key processes of silicon-wafer direct bonding (SDB), including hydrophilic surface formation and optimal two-step heat treatment, have been developed However, H2SO4/H2O2 solution being a strong oxidized acid solution, native oxide is found to have grown on the wafer surface as soon as a wafer is treated in this solution. In the case of a wafer further treated in diluted HF solution after hydrophilic surface formation, it is shown that the wafer surface can not only be cleaned of its native oxide but also remains hydrophilic, and can provide excellent voidless bonding. The N+/P and N/P combination junction mesa diodes fabricated on the wafers prepared by these novel SDB technologies are examined. The ideality factor n of the N/P mesa diode is 2.4 approximately 2.8 for the voltage range 0.2 approximately 0.3 V; hence, the lowering of the ideality factor n is evidently achieved. As for the N+/P mesa diode, the ideality factor n shows a value of 1.10 approximately 1.30 for the voltage range 0.2 approximately 0.6 V; the low value of n is attributed to an autodoping phenomenon which has caused the junction interface to form in the P-silicon bulk. However, the fact that the sustaining voltage of the N/P mesa diode showed a value greater than 520 V reveals the effectiveness of our novel SDB processes.
EFFECT OF HYDROGEN ON DEPOSITION OF TANTALUM NITRIDE THIN-FILMS FROM ETHYLIMIDOTANTALUM COMPLEX
(1992-05-01)
CHIU, HT
;
CHANG, WP
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
DETECTION OF CRACKS IN STRUCTURES USING MODAL TEST DATA
(1992-05-01)
KAM, TY
;
LEE, TY
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
A nondestructive evaluation procedure is presented for identifying a crack in a structure using modal test data. The structure is discretized into a set of elements and the crack is assumed to be located within one of the elements. Measured vibration frequencies and mode shapes are used in an identification process to identify the cracked element based on a simple reduced stiffness model. Static deflection analyses of the structure with and without a crack are performed and a strain energy equilibrium equation is constructed for determining the size of the crack. The detection of a crack on a damaged beam is used to illustrate the applications of the proposed procedure. The present procedure is general and can be easily extended to complex structures with multiple cracks.
SUPERCONFORMAL DEFORMATION, ZERO-NORM STATES AND SPACE-TIME SYMMETRIES OF THE SUPERSTRING THEORIES
(1992-05-01)
LEE, JC
;
交大名義發表
;
電子物理學系
;
National Chiao Tung University
;
Department of Electrophysics
We present a formalism to study type II and Heterotic superstrings with massless and massive background fields in the bosonic sector. This formalism is appropriate to study high energy symmetries of the superstring. As an example, we explicitly relate all massless symmetries to the massless zero-norm states in the spectrum. This includes the E8 x E8 and SO(32) gauge symmetries in the ten-dimensional Heterotic string. The first (even G-parity) massive level is briefly described. We then argue the existence of new symmetries for the massive Yang-Mills-like gauge bosons and tensor fields at each fixed mass level. These enlarged stringy symmetries correspond to the decoupling of massive zero-norm states in the spectrum.
A DISTRIBUTED STATE ESTIMATOR FOR ELECTRIC-POWER SYSTEMS
(1992-05-01)
LIN, SY
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
;
Institute of Electrical and Control Engineering
In this paper, we develop a theoretically robust and computationally efficient distributed state estimator, which is to solve the WLS problem by using distributed computation, for the power system. This distributed state estimator aims at its utilization in the decentralized control, and it is executing in a data communication network which is assumed to be topologically the same and physically in parallel with the power network. Along with this state estimator, we can obtain several attractive satellite functions which include (1) reduction of the time-skew problem, (2) being free from the power network topological error, (3) easy identification of the unobservable states and (4) bad data detection and identification. We have analyzed the computation complexity of this distributed state estimator. Moreover, we have also simulated this state estimator on several cases of the IEEE 30-bus system. The numerical accuracy of the simulation results are satisfactory, and the estimated computation time including the communication delay demonstrates the excellent computational performance of the distributed state estimator.
STUDY OF ACOUSTIC-RESONANCE IN ENCLOSURES USING EIGENANALYSIS BASED ON BOUNDARY ELEMENT METHODS
(1992-05-01)
BAI, MR
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
;
Department of Mechanical Engineering
It is well known that, from the modal theory of room acoustics, resonance will occur if the driving frequency of a sound source located in a room coincides with one of the natural frequencies of the sound field. In this study, an eigenanalysis technique based on the boundary element method (BEM) is developed for extracting eigenmodes of a sound field in an enclosure. A method of singular value search, in conjunction with a golden section optimization algorithm, is utilized for efficient calculation of eigenmodes. In particular, modes associated with repeated eigenvalues can be well resolved by the technique developed in this research. Enclosures of various geometries have been analyzed by using the developed algorithm in a numerical simulation. Satisfactory agreement has been achieved between the BEM results, the FEM results, and the analytical solutions if available.
DETECTION OF ROTATIONALLY SYMMETRICAL SHAPE ORIENTATIONS BY FOLD-INVARIANT SHAPE-SPECIFIC POINTS
(1992-05-01)
LIN, JC
;
CHOU, SL
;
TSAI, WH
;
資訊工程學系
;
Department of Computer Science
Two new types of shape-specific points, called fold-invariant centroid (FIC) and fold-invariant radius weighted mean (FIRWM), are introduced for detecting the orientations of rotationally symmetric shapes. A given rotationally symmetric shape is first transformed into a new fold-invariant shape. The centroid and the radius weighted mean of the new shape are then transformed back to obtain the proposed FIC and FIRWM, respectively. FIC and FIRWM points are proved to be invariant to translation, rotation and scaling, and so can be used for matching rotationally symmetric shapes. Using the proposed fold-invariant shape-specific points to detect the orientations of rotationally symmetric shapes is easier to implement than that of using the fold principal axes. Some illustrative examples and a method to avoid the case where the proposed fold-invariant shape-specific points are too close to the centroid are also given.
CRYPTOGRAPHIC KEY ASSIGNMENT SCHEME FOR ACCESS-CONTROL IN A HIERARCHY
(1992-05-01)
CHANG, CC
;
HWANG, RJ
;
WU, TC
;
資訊工程學系
;
Department of Computer Science
A cryptographic key assignment scheme for access control in a user hierarchy is proposed. The users and their owned information items are classified into disjoint sets of security classes where the hierarchy on security classes is an arbitrary partial order. Based on Newton's interpolation method and a predefined one-way function, each security class C(i) is assigned a secret key SK(i) and some public parameters (P1i, P2i). The information items owned by the security class C(i) are encrypted by an available symmetric cryptosystem with the enciphering key SK(i). Through the computing of the assigned security key and the public parameters, only the security class in the higher level can derive any of his successors' secret keys. Thus, only the security classes in the higher level can access the information items owned by the security classes in the lower level. We also show that our proposed scheme is not only secure but also practical.
THE EFFECTS OF GASB/INAS BROKEN GAP ON INTERBAND TUNNELING CURRENT OF A GASB/INAS/GASB/ALSB/INAS TUNNELING STRUCTURE
(1992-05-01)
CHEN, JF
;
CHO, AY
;
電子物理學系
;
Department of Electrophysics
We propose and study a new GaSb/InAs/GaSb/AlSb/InAs broken-gap interband tunneling diode by varying the thicknesses of the InAs layer. A twice-higher peak current density and a three-times-higher peak-to-valley current ratio in the proposed structure with a 30-angstrom-thick InAs layer were observed relative to the structure with no InAs layer. This result indicates that the characteristic of the negative differential resistance can be improved simply by placing a thin effective InAs barrier on the GaSb side of the GaSb/AlSb/InAs single-barrier structure. The increase of the peak current is interpreted as the result of forming a quasi-bound state in the GaSb well. This interpretation is supported by the observation that the current-voltage characteristic of the proposed structure is similar to that of a conventional GaSb/AlSb/GaSb/AlSb/InAs double-barrier interband tunneling structure.
TENSILE PROPERTIES OF A DO3-CONTAINING FE-MN-AL-SI-C ALLOY AT ELEVATED-TEMPERATURES
(1992-05-01)
CHOU, JS
;
CHAO, CG
;
機械工程學系
;
材料科學與工程學系
;
Department of Mechanical Engineering
RECOGNITION OF HANDWRITTEN CHINESE CHARACTERS VIA SHORT LINE SEGMENTS
(1992-05-01)
LEE, HJ
;
CHEN, B
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
A system to recognize handwritten Chinese characters is presented. In the first stage, short line segments are extracted, where a new efficient algorithm is proPosed, based on accumulated chain codes, for line approximation. In the feature extraction stage, features of each character are computed, which are further defined by the features of its composing line segments. In the matching stage, dynamic programming is first used to calculate the similarity between a segment of the input character and a segment of the reference character, and then the similarity between the two characters is computed. In order to reduce the number of candidates, a coarse classification algorithm is proposed. The recognition rate for 150 characters is about 90%, excluding the error in coarse classification.
A FLEXIBLE PARALLEL ARCHITECTURE FOR RELAXATION LABELING ALGORITHMS
(1992-05-01)
LIN, SY
;
CHEN, Z
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
The design of a flexible parallel architecture for both the discrete relaxation labeling (DRL) algorithm and the probabilistic relaxation labeling (PRL) algorithm is addressed. Through the analysis of parallelism in the computational models of both algorithms, the parallel execution of the algorithms on a flexible parallel architecture is presented. Three basic types of parallel operations are performed in the architecture: simultaneous, pipeline, and systolic. An illustrative example is used to show how the DRL algorithm can be executed on the parallel architecture. In doing so the processing element (PE) organization and the combiner organization of the architecture are described. The same architecture with programmable functional units is shown to be able to execute the PRL algorithm, too. The performance comparisons between the proposed architecture and some other existing ones are also given.
EXTENDED LQG SELF-TUNING CONTROLLER IN A MIXED BACKGROUND
(1992-05-01)
LEE, BK
;
LIN, YP
;
電控工程研究所
;
Institute of Electrical and Control Engineering
We consider the problem of constructing a LQG-based adaptive controller so that the control system can track a deterministic command signal and simultaneously regulate stochastic disturbances. A new measure for mixed signal in the feedback loop is first introduced. Then a generalized cost function is formulated and the optimal 'extended LQG controller' can be constructed by solving a diophantine equation. Based on the extended LQG design, a self-tuning controller can be constructed. System tracking performance under ergodic process noise is analysed in detail and better results are obtained. Finally, the optimal tracking performance is attained if the parameter estimates converge to their true values.