We are aming to develop a computer-based consultant system which helps novice computer users to achieve their task goals on computers through natural language dialogues. Our target is spoken Japanese. To develop effective methods for processing spoken Japanese, it is essential to analyze real dialogues and to find the characteristics of spoken Japanese. In this paper, we discuss the design problems associated with constructing a spoken dialogue database from the viewpoint of advisory dialogue collection, describe XMH (X-window-based electronic mail handling program) usage experiments made to collect advisory dialogues between novice XMH users and an expert consultant, and show the dialogue database we constructed from these dialogues. The main features of our database are as follows: (1) Our target dialogues were advisory ones. (2) The advisory dialogues were all related to the use of XMH that has a visual interface operated by a keyboard and a mouse. (3) The primary objective of the users was not to engage in dialogues but to achieve specific task goals using XMH. (4) Not only what the users said but also XMH operations performed by the users are included as dialogue elements. This kind of dialogue database is a very effective source for developing new methods for processing spoken language in multimodal consultant systems, and we have therefore made it available to the public. Based on our analysis of the database, we have already developed several effective methods such as a method for recognizing user's communicative intention from a transcript of spoken Japanese, and a method for controlling dialogues between a novice XMH user and the computer-based consultant system which we are developing. Also, we have proposed several response generation rules as the response strategy for the consultant system. We have developed an experimental consultant system by implementing the above methods and strategy.

The selection of an appropriate key search algorithm for a specific application field is an important issue in application systems development. This is because data retrieval is the most time-consuming part of many application programs. An automatic selection method for key search algorithms is presented in this paper. The methodology has been implemented in a system called KESE2 (KEy-SEarch ALgorithm SElection). Key search algorithms are selected according to the user's requirements through interaction with KESE2 which bases its inferences on an evaluation table. This evaluation table contains values rating the performance of each key search algorithm for the different searching properties, or characteristics. The selection algorithm presented is based on step by step reduction of unsuitable key search algorithms and searching properties. The paper also proposes assistance facilities that consist of both a support function and a program synthesis function. Experimental results show that the appropriate key search algorithms are effectively selected, and that the necessary number of questions asked, to select the appropriate algorithm, is reduced to less than half of the total number of possible questions. The support function is useful for the user during the selection process and the program synthesis function fully translates a selected key search algorithm into high level language in an average of less than 1 hour.

Efficiency of network resource can be improved by statistical multiplexing in ATM networks. If cell traffic characteristics of each connection could be obtained beforehand, we could admit maximum connections while satisfying the QoS (Quality of Service) objective. Since such traffic characteristics as an average rate and a mean burst length are difficult to anticipate, only peak rate will be used for CAC (connection admission control). The peak rate assignment strategy will, however, lead to inefficient network utilization for bursty traffic. This paper proposes an adaptive admission control using real-time traffic measurements to overcome the above problem. This scheme is based on two-state cell stream model composed of overload and underload states. The two-state model simplifies the measuring algorithm, which is suited for online processing. Performance of this scheme is investigated through simulation study for multiplexing of on-off sources with a wide spectrum of traffic characteristics. Since the proposed control scheme exploits measurements of cell streams, it achieves nearly optimum bandwidth efficiency.

A number of flexible control mechanisms used in buffer management, congestion control and bandwidth allocation have been proposed to improve the performance of ATM networks by introducing parameters, such as threshold, push-out probability and incremental bandwidth size of a virtual path, which are adjustable by network providers. However, it is difficult to adaptively adjust these parameters, since the traffic in ATM networks is further complicated by accommodating various kinds of services. To overcome the problem, we propose in this paper a control scheme based on the genetic algorithms and the neural estimator. The neural estimator forecasts the future QOS values for each candidate parameter set, and the genetic algorithms select the best one to control the real network. An example of buffer management in an ATM switch is examined in this paper. Simulation results show the effectiveness of the proposed control scheme in adaptively adjusting the parameter set even when the traffic environment and the QOS requirements are dynamically changing.

This paper discusses two approaches to statistical multiplexing: rate envelope multiplexing, allowing resource sharing with small delays for low peak rate connections, and rate sharing, based on the use of large multiplexer buffers to ensure high link utilization for high speed data traffic. We argue that the weighted fair queueing scheduling algorithm provides an efficient means for combining both kinds of multiplexing in the B-ISDN. A feasible implementation known as Virtual Spacing is outlined. We illustrate the flexibility of the proposed scheme by showing how different service categories could be provided.

Data communication by using TCP/IP is one of important services on ATM networks. At one approach in traffic control of this service, the dedicated bandwidth for data transfer is not guaranteed and the feedback congestion control to prevent cell loss is performed in the congestion case. However, when a large quantity of data is transferred within a short period, this traffic control cannot be expected to achieve high efficiency. In this case, it is suitable that the dedicated bandwidth is guaranteed by FRP (Fast Reservation Protocol) before the data is transferred. This paper describes that FRP is superior to the feedback congestion control for large size data transmission. Next, it proposes a selectable traffic control which selects adaptively one of the feedback congestion control and FRP.

The recent progress of B-ISDN signaling systems has enabled networks to handle calls which require a wide variety of ATM connection sets. This paper is concerned with the circuit group which handles calls requesting asymmetric forward and backward multi-connections, and has the capability of both bandwidth negotiation and bandwidth reservation as a traffic control for enhancing call blocking performance. A model of the circuit group is first established focusing on the call level characteristics of the group, and then a method based on the reduced load approximation and an approximate analysis of a multirate group is proposed for calculating approximate blocking probabilities. The accuracy of the approximation method is evaluated numerically by comparing with an exact method and simulation. Further the impact of bandwidth negotiation and reservation on call blockings is examined based on numerical examples.

This paper describes reverse modulation carrier recovery with a tank-limiter for Offset QPSK (OQPSK) burst signals. Acquisition performance is discussed taking into account hardware implementation errors in the carrier recovery circuit. The results indicate hardware implementation errors cause a significant recovered carrier phase error during BTR (Bit Timing Recovery) of OQPSK burst signals. A phase error reduction technique by modifying the BTR code for OQPSK burst signals is proposed to improve the acquisition performance. Computer simulation and hardware experiments confirmed its improvement. The performance of a prototype OQPSK burst demodulator using the proposed carrier recovery scheme is also presented.

A Hierarchical Cubic Network (HCN) is a hierarchical hypercube network proposed by Ghose. The HCN is topologically superior to many other similar networks, in particular, the hypercube. It has a considerably lower diameter than a comparable hypercube and is realized using almost half the number of links per node as a comparable hypercube. In this paper, we propose the shortest routing algorithm in HCN(n, n) and show that the diameter of HCN(n, n) with 22n nodes is n(n1)/31 which is about 2/3 of that of a comparable hypercube. We also propose the optimal routing algorithm in HCN(m, n) where mn and obtain that its diameter is n(m1)/31. Typical parallel algorithms run in HCN(m, n) with the same time complexity as a hypercube and the hypercube topology can be emulated with O(1) time complexity in it.

This paper proposes a practical training algorithm for artificial neural networks, by which both the optimally pruned model and the optimally trained parameter for the minimum prediction error can be found simultaneously. In the proposed algorithm, the conventional information criterion is modified into a differentiable function of weight parameters, and then it is minimized while being controlled back to the conventional form. Since this method has several theoretical problems, its effectiveness is examined by computer simulations and by an application to practical ultrasonic image reconstruction.

In this paper, we report a new approach about parsing and searching problem for a given phonetic lattice. The approach is based on the Divide and Conquer (DC) strategy. By dividing the phonetic lattice, we first construct a PD-tree to represent this lattice, then, we parse through this PD-tree to identify the possible sentence which is supposed to be the speech utterance. Next, we propose a new search scheme called Downward Request (DR) search model to decrease the computation costs, and this search model gives us the optimal or N-best solutions. Experiments performed on Chinese speech recognition show us the good results.

In this paper, the ATM Mini-Bar System (AMBS) which is a future information providing service infrastructure is proposed. The purpose of AMBS is to provide a multi-media environment in which a user can (1) select and get quickly any needed information, in low cost, at any time, among very large amount of different media information provided by a variety of providers, (2) be charged only for the information which is selected and used, (3) edit or process informations into users' individually requested style or format before using them. The basic concept and configurations of AMBS are also addressed. This system is basically a center-end oriented one-way information providing system. The information center broadcasts its contents to all user equipments based on a user request forecast, and every user equipment stores the delivered contents in its large storage. A user can select one's needed informations from the storage, and may edit or process them within the user equipment. The charge is only on the read informations from the storage, not on all contents in it. The key points of this system are the following three. (A) Introduction of a broadcast (or multicast) media for economical information delivery (exactly speaking, it is a predelivery which means a delivery before request) to user equipments. (B) Introduction of a 1 to 1 communication network for selective charging and control of each user equipments. (C) Introduction of the user equipment storage for Quick response to user information request in most cases with the broadcast (or multicast) information delivery media described above, Separation of information delivery speed and replay speed to increase system flexibility, Local user information processing or editing. As an example of technical solutions, a memory architecture, which is based on hierarchical architecture, is described. AMBS is expected to give some impacts to information industries because it can integrate many kinds of services into the same platform, but some standerdization items are needed to realize it.

We propose a directly controlled emitter-follower circuit with a feedback type level stabilizer for low-voltage, low-power and high-speed bipolar ECL circuits. The emitter-follower circuit employs a current source structure that compensates speed and power for various supply voltage and temperature. The feedback controlled circuit with a small current source stabilizes 'High' level. At a power consumption of 1 mW/gate, the new circuit is 45% faster under the loaded condition (FO1, CL0.5 pF) and has 47% better load driving capability than conventional ECL gates.

With the development in portable electronic equipment, the demand for secondary batteries of high energy density is increasing. Recently, nickel metal hydride secondary batteries (Ni/MH) are expanding the market, and lithium ion secondary batteries have been newly developed and commercialized. This paper describes in detail Ni/MH and lithium ion secondary batteries, and reports on their development state and characteristics.

We extend the theorem of Gramlich on modular termination of term rewriting systems, by relaxing the disjointness condition and introducing the composability instead. More precisely, we prove that if R1, R-1 are composable, terminating term rewriting systems such that their union is nonterminating then for some a {1, -1}, Ra OR is nonterminating and R-aRa is Fa-lifting. Here, OR is defined to be the special system {or(x, y) x, or(x, y) y}, Fa is the set of function symbols associated with Ra, and an Fa-lifting system contains a rule which has either a variable or a symbol from Fa at the leftmost position of its right-hand side. The extended theorem is stronger than the original one in that it relaxed the disjointness and constructor-sharing conditions and allowed the two systems to share defined symbols in common under the restriction of composability. The corollaries of the theorem show several sufficient conditions for decomposability of termination, which are useful for proving termination of term rewriting systems defined by combination of several composable modules.

A low power bus architecture with Local and Global Charge-Recycling Bus (Local-CRB and Global-CRB) techniques, featuring virtual stacking of the individual bus-capacitance and the dummy capacitor into a series configuration between supply voltage and ground, has been proposed. These Local and Global CRB schemes make it possible to reduce not only each bus-swing but also a total equivalent bus-capacitance of the ultra multi-bit buses running in parallel. The voltage swing of each bus is given by the recycled charge-supplying from the upper adjacent bus capacitance or the dummy capacitor, instead of the power line. The dramatical power reduction was verified by the simulated and measured data. According to these data, if employing the combination of those CRB schemes in a practical chip, the ultra-high data rate of 25 Gb/s can be achieved while maintaining the power dissipation to be less than 300 mW at Vcc3.6 V for the bus width of 512 bit with the bus-capacitance of 14 pF per bit operating at 50 MHz.

Device models for a laser diode, photodetector, MESFET, HEMT, bipolar transistor, diode, and resistor are proposed and are implemented in a commercial mixed-signal simulator along with models for an optical fiber, an external optical modulator, and a pulse pattern generator. The validity of the models is confirmed by comparing simulated and experimental results. The performance of a mixed photonic/electronic circuit, which is determined by a large-signal waveform and the device noises, is estimated by the present analysis method.

A 10-kW (53V/200A), forced-air-cooled DC-DC converter has been developed for fuel cell systems. This converter uses new high-voltage bipolar-mode static induction transistors (BSIT), a new driving method, a zero-voltage-switched pulse-width-modulation technique, and a new litz wire with low AC resistance. It weighs only 16.5kg, has a volume of 26,000cm3, operates at 40kHz, and has a power conversion efficiency of about 95%. The power loss of this converter is 20% less than that of conventional natural-air-cooled DC-DC converters, and the power density is 3 times as high.

In this paper, it is stated that visualization and abstraction of program specifications can be highly integrated on the basis of decision tables and condition expressions. In order to demonstrate this idea, we developed an automatic programming system called SPACE: SPecification Acquisition and Compiling Engine. SPACE is designed to ease the production of business data processing program. SPACE has functions both to support the creation of visual program specifications and to generate COBOL programs according to the input program specifications. To visualize program specification, SPACE design windows are comprised of two diagrams and four tables in a format similar to the conventional detailed design sheets. To represent module functions, in particular, a visualized computation model called a decision table is used. All the possible execution states of a module are represented by combining the state function called condition expressions. The condition expressions represent the typical file processing patterns in very familiar form to actual business application designer. They do not simply give function values; each of them carries out implicit attached procedures according to the characteristic I/O control logic for business data processing. Hence users can describe program specifications concisely by designating merely the condition expression instead of the detailed I/O control logic. This paper uses sample descriptions of stock control problems to explain how visualization of computation and abstraction of algorithm can be integrated and formalized on a basis of a decision table and a condition expression. Also the paper describes how to generate programs from visual specifications.

A method for painting a sequence of monochromatic images is proposed. In this method, a color model, whose base components are hue, saturation and intensity, is used to keep the lightness of images unchanged before and after painting. Two successive frames in the monochromatic image sequence and a colored image of the first frame which is interactively painted, are analyzed in order to paint the next monochromatic frame. The painting process is composed of two phases, that is, an automatic coloring phase and an interactive retouching phase. In the automatic coloring phase, hierarchical image segmentation and region matching procedures are performed, and the two attributes of hue and saturation are mapped from the painted image of the first frame to the next image. In the retouching phase, using an interactive paint system based on the color model, users can modify the chromatic components of pixels whose colors were not mapped correctly. Several experiments show that our method is very effective in reducing tedious painting.