Fiber-optic local area networks (LANs) with Fiber Distributed Digital Interface (FDDI) protocol have come into use as backbones connecting other small LANs. This paper describes the current status of LANs, reviews a number of issues that stand in the way of further development and look at the future of LANs. Demands for wide-area networks (WANs) connecting LANs and multimedia LANs including voice and image capability has been extremely strong, spurring progress in geographical expansion and throughput increase, now over 100Mbit/s. The logical choice of transmission medium for next-generation systems is single-mode optical fiber, not only for backbone LANs but also, eventually, for floor LANs.

In this paper, we propose an algorithm of O(|V|min{k,|V|,|A|}|A|) time complexity for finding all k-edge-connected components of a given digraph D=(V,A) and a positive integer k. When D is symmetric, incorporating a preprocessing reduces this time complexity to O(|A|+|V|2+|V|min{k,|V|}min{k|V|,|A|}), which is at most O(|A|+k2|V|2).

A new redundancy technique especially suitable for ultra-high-speed static RAMs (SRAMs) has been developed. This technique is based on a decoding-method that uses two kinds of fuses without introducing any additional delay time. One fuse is initially ON and can be turned OFF afterwards, if necessary, by a cutting process using a focused ion beam (FIB). The other is initially OFF and can be turned ON afterwards by a connecting process using laser chemical vapor deposition (L-CVD). This technique is applied to a 64 kbit SRAM having a 1.5-ns access time. The experimental results obtained through an SRAM chip repaired using this redundancy technique show that this technique does not introduce any increase in the access time and does not reduce the operational margin of the SRAM.

When we study time-domain electromagnetic fields, we frequently use the finite-difference time-domain (FD-TD) method. In this paper, we discuss errors of the FD-TD method and present the optimum mesh spacings in the FD-TD method when the three mesh spacings are different.

This paper discusses a formulation of a basic theory of the information systems, where information is not only transmitted, but is also processed and memorized during the transmission. A deterministic procedure applied by an information system is defined as a logical work, and two measurements with information X, information quantity I(X) and information vitality T(X), are introduced. A system with the ability of transmitting, processing and memorizing information is called an information engine. A system of interconnected information engines is called an information network. The power of an information engine is defined as the maximum capacity of the logical works performed by the engine, and important properties of total power of information network are derived. Response time characteristics and cost minimizing problems of an information network are also discussed.

Broadband multimedia information environments are part of the next big advance in communications and computer technology. The use of multimedia infrastructures in offices is becoming very important. This paper deals with a service concept and human interfaces based on a paper metaphor. The proposed service offers the advantages of paper and eliminates the disadvantages. The power of multimedia's expressiveness, user interaction, and hypermedia technology are key points of our solution. We propose a system configuration for implementing the service/human interface.

Some problems in formal language theory are considered and are shown to be deterministic exponential time complete. They include the problems for a given context-free grammar G, a nondeterministic finite automaton M, a deterministic pushdown automaton MD, of determining whether L(G)L(M), and whether L(MD)L(M). Polynomial time reductions are presented from the pebble game problem, known to be deterministic exponential time complete, to each of these problems.

A discrete-time neuron model having a refractory period and containing a binary hysteresis output function is introduced. A detailed mathematical analysis of the output response is carried out and the necessary and sufficient condition which a sequence must satisfy in order to be designated as a periodic response of the neuron model under a constant or periodic stimulation is given.

The robust finite settling time stabilization problem is considered for a multivariable discrete time plant with structured uncertainties. Finite settling time (FST) stability of a feedback system is a notion introduced recently for discrete time systems as a generalization of the dead-beat response. The uncertain plant treated in this paper is described by (E0+ΣKi=1qiEi)x(t+1)(A0+ΣKi=1qiAi)x(t)+(B0+ΣKi=1qiBi)u(t), and y(t)=(C0+ΣKi=1qiCi)x(t) where Ei, Ai, Bi and Ci (0iK) are prescribed real matrices and qi (1iK) are uncertain parameters restricted to prescribed intervals [qi, i]. It is shown in this paper that a controller robustly FST stabilizes such an uncertain plant, if, the uncertain plant satisfies some conditions, and the controller simultaneously FST stabilizes a finite set of plants. The result leads to a testable necessary and sufficient condition of the existence of a solution to the robust FST stabilization problem, and a systematic method of designing a robust FST stable feedback system, in the case where the plant contains only one uncertain parameter.

Real-time database systems have the properties of database and real-time systems. This means they must keep timing constraints of transactions as required in real-time systems, and at the same time ensure database consistency as required in database systems. Real-time concurrency control is a general approach for resolving this conflict. In this type of control, a concurrency control technique for database systems is integrated with a task scheduling technique for real-time systems. This paper surveys previous studies on real-time concurrency control and considers future research directions.

This paper describes a task-oriented speech dialogue system based on spontaneous speech understanding and response generation (TOSBURG). The system has been developed for a fast food ordering task using speaker-independent keyword-based spontaneous speech understanding. Its purpose being to understand the user's intention from spontaneous speech, the system consists of a noise-robust keyword-spotter, a semantic keyword lattice parser, a user-initiated dialogue manager and a multimodal response generator. After noise immunity keyword-spotting is performed, the spotted keyword candidates are analyzed by a keyword lattice parser to extract the semantic content of the input speech. Then, referring to the dialogue history and context, the dialogue manager interprets the semantic content of the input speech. In cases where the interpretation is ambiguous or uncertain, the dialogue manager invites the user to confirm verbally the system's understanding of the speech input. The system's response to the user throughout the dialogue is multimodal; that is, several modes of communication (synthesized speech, text, animated facial expressions and ordered food items) are used to convey the system's state to the user. The object here is to emulate the multimodal interaction that occurs between humans, and so achieve more natural and efficient human-computer interaction. The real-time dialogue system has been constructed using two general purpose workstations and four DSP accelerators (520MFLOPS). Experimental results have shown the effectiveness of the newly developed speech dialogue system.

In this paper, we investigate the round complexity of zero-knowledge interactive proof systems of possession of knowledge, and mainly show that if a relation R has a three move blackbox simulation zero-knowledge interactive proof system of possession of knowledge, then there exists a probabilistic polynomial time algorithm that on input x{0,1}*, outputs y such that (x,y)R with overwhelming probability if xdom R, and outputs "" with probability 1 if x dom R. The result above can not be generalized to zero-knowledge interactive proof systems of possession of knowledge with more than four moves, because it is known that there exists a "four" move blackbox simulation perfect zero-knowledge interactive proof system of possession of knowledge for a nontrivial relation R.

One model of a laser is a set of differential equations called the Maxwell-Bloch equations. Actually, in a physical system, causing a chaotic behavior is very difficult. However the chaotic behavior can be observed easily in the system which has a mirror to feedback the delayed output.

A model for time spread-pulse position modulation (TS-PPM)/code division multiple access (CDMA) systems is presented. A TS signal is produced by a TS-filter, whose characteristic is a pseudonoise sequence in frequency domain. The error probability performance is analyzed and compared with those of on-off keying (OOK) and binary phase shift keying (BPSK). It is shown that at the same transmission speed TS-PPM is superior to TS-OOK and TS-BPSK due to the dramatic decrease of multiple access interference. The throughput of the network is analyzed, and its relation to the length of pseudonoise sequence and the packet length is also discussed.

Let TBP be the server busy period of an M/G/1 queueing system characterized by arrival intensity λ and service time c.d.f. A(τ). In this paper, we investigate the regularity structure of the Laplace transform σBP(s)=E[] on the complex s-plane. It is shown, under certain broad conditions, that finite singular points of σBP(s) are all branch points. Furthermore the branch point s0 having the greatest real part is always purely negative and is of multiplicity two. The basic branch point s0 and the associated complex structure provide a basis for an asymptotic representation of various descriptive distributions of interest. For a natural relaxation time |s0|-1 of the M/G/1 system, some useful bounds are obtained and the asymptotic behavior as traffic intensity approaches one is also discussed. Detailed results of engineering value are provided for two important classes of service time distributions, the completely monotone class and the Erlang class.

The subject of the paper is to propose two approximation algorithms FM_SPLA, FM_DPLA for priority-list scheduling in timed Petri nets. Their capability is compared with that of existing algorithms SPLA, DPLA through experimental results, where SPLA and DPLA have previously been proposed by the authors.

Air-bridge metal interconnection technology is used for upper level power supply line interconnections in GaAs LSI's to reduce the signal propagation delay time. This technology reduces both parasitic capacitance between the signal line and the power supply line, and propagation delay in the signal line to about 10% and about 50%, respectively, compared to conventional 3-level interconnections without air-bridges. Under standard load conditions (FI=FO=2, length of load line=2 mm), the air-bridge technique leads to gate propagation delays which are about 60% of those in conventional interconnections. We fabricated 2.1-k gate Gate Arrays and 4-kb SRAM's using the air-bridge structure to interconnect power supply lines. For a Gate Array with 0.7 µm gate Buried P-layer Lightly Doped Drain (BPLDD) FET's, the typical gate propagation delay under standard load conditions was about 110 ps with a dissipation power of 1.4 mW/gate. SRAM's with 05 µm gate BPLDD's had typical access time (tacc) of 1.5 ns with a dissipation power of 700 mW/chip.

A job shop system typically seen in flexible manufacturing systems (FMS) is a system composed of a set of machines and a various kind of jobs processed with the machines. A production system of semiconductor fabrication is an example of job shop systems, which has main features of repetitive processes of one part and set-up times required for machines processing different types of parts. On the other hand, timed Petri nets are used for modelling and analyzing a wide variety of discrete event systems. There are many applications of timed Petri nets to the scheduling problems of job shop systems. The performance evaluation and steady state behaviors are studied by using the maximum cycle time of timed marked graphs. The aim of this paper is to propose a new model for production systems including repetitive processes and set-up time requirements which enables the quantitative analysis of real time system performance. In job shop systems such as a semiconductor fabrication system, it takes considerable amount of set-up time to prepare different types of chemical reactions and the model should take account of a set-up time for each machine. We focus upon the relationship between facility utilization factor and production cycle time in the steady state. In the proposed model, the minimum total set-up time can be attained. Quantitative relationship between utilization factor and production cycle time is derived by using the proposed model. A utilization factor of a system satisfying a given limit of the cycle time is evaluated, and the improvement of the utilization factor is considered. Conversely, we consider the improvement of the cycle time of a system satisfying a given limit of utilization factor.

The paper describes the design considerations, fabrication process and performance of the newly developed 1-K ECL gate array implemented with fully self-aligned AlGaAs/GaAs hoterojunction bipolar transistors (HBTs). This gate array consists of 960 three-input OR/NOR ECL basic gates. It contains about 7,600 transistors in a chip area 8.15-mm8.45-mm. The basic (FI=FO=1, wiring length L=0-mm) and loaded (FI=FO=3, L=1-mm) gates exhibit delay times of 33-ps and 82-ps, respectively, with 8.5-mW/gate power dissipation. From the measured values, fan-in, fan-out and wiring delay times of 9-ps/FI, 7-ps/FO and 17-ps/mm are estimated, respectively. These results are in good agreement with the designed results obtained using "SPICE" simulation.

The subject of the paper is the minimum initial marking problem for scheduling in timed Petri net PN: given a vector X of nonnegative integers, a P-invariant Y of PN and a nonnegative integer π, find an initial marking M minimizing the value YtrM among those initial marking M such that there is a scheduling σ having the total completion time τ(σ)π with respect M , X and PN (a sequence of transitions, with the first transition firable on M , such that every transition t can fire prescribed number X(t) of times). The paper shows NP-hardness of the problem and proposes two approximation algorithms with their experimental evaluation.