This paper deals with communication model in a software development project when there happens some trouble on it. First, we analyze a communication process in the real projects, and investigate what type of communication exists and which aspect is thought to be important by the members of the projects. Then we propose a communication model based on the analysis. We focus on the communication in case of troubles, and the process is modeled using charge, competence and knowledge of each member in the project. The features of the model lies in the ability to simulate communication route dynamically. The results of the simulation is compared with the real data, and also the use of the model for communication support system is discussed.

Proposed here is an internal representation and mapping method for multimedia information in which retrieval is based on the impression documents desired to make. A user interface design for a system using this method is also proposed. The proposed internal representation and mapping method represents each desired document impression as an axis in a semantic space. Documents are represented as points in the space. Queries are represented as subspaces. The proposed user interface design employs a method of visual presentation of the semantic space. Pictorial examples are given to illustrate the range of impressions represented by the axes. The relations between the axes are represented by dispersion diagrams for the documents stored in the document base. With this method, the user can intuitively decide the appropriate subspace for his needs and can specify it directly. For evaluation purposes, a prototype system has been developed. An image retrieval experiment shows that the proposed internal representation and mapping method and the user interface design provide effective tools for information retrieval.

Theoretical network analysis of a network constructed of "Interconnectable Star Couplers" whose all diagonal elements of transmission matrix are zero is investigated. Under certain connection rules, Interconnectable Star Coupler can be connected each other without oscillation and ghost formation. The rules are: (1) Network should not contain any loop. (2)Only single port pair should be connected between neighbor star couplers. (3)Network shold not contain any usual star coulpler. "Coupled Star Network", which is constructed under the connection rules, is able to form Cascade Star topology, Stratified Star topology and their mixed topology. It is shown that the Coupled Star Network is equivalent to a large Interconnectable Star Coupler so that bidirectional communication, which can add confidentiality to the broadcasting bus and doubles communication capacity, is available. A new configuration of Coupled Star Network using passive Interconnectable Star Couplers and optical amplifiers is proposed. This network has two separated bidirectional communication channel which can be applied for so-called Multimedia LAN. As a result of comparison between Cascade Star topology and Stratifide Star topology, it is shown that the latter topology is superior to former topology, from the view point of signal degeneration and maximum round trip delay time. Cascade Star topology, however, is superior to Stratified Star topology from the angle of total fiber length. Accordingly, optimized network topology is thought to be mixed topology of these.

We review the role of optics in interconnects, analog processing, neural networks, and digital computing. The properties of low interference, massively parallel interconnections, and very high data rates promise extremely high performance for optical information processing systems.

We consider applications of optical solitons to signal processing. Soliton switching devices promise ultrafast operation and compatibility with communications systems using optical pulses. Quantum soliton effects include broadband squeezing and quantum nondemolition measurements, and can reduce noise and increase sensitivities of optical measurements. We report the demonstration of two-color soliton switching and describe progress towards implementation of quantum nondemolition measurement of photon number using soliton collisions.

The VSTEP concept and its practical application in the form of an LED-type pnpn-VSTEP demonstrating low power consumption through electro-photonic operational modes are both shown. Further, with focus primarily on the new laser-mode VSTEP with high-intensity light output and narrow optical beam divergence, the design features such as threshold gain and optical absorptivity, device fabrication, and characteristics are explained. The possibility of ultimate performance based mainly on electrical to optical power conversion efficiency, important from the application viewpoint of optical interconnection, are also discussed. Also, as two examples of functional optical interconnection achieved by VSTEP, serial-to-parallel data conversion and optical self-routing switches are shown. Finally, future opto-electronic technologies to be developed for two-dimensionally integrable surface-type optical semiconductor devices, including the VSTEP, are discussed.

We studied transient fields on a perfectly conducting sphere excited by a half sine pulse wave and examined the Poynting vectors, the energy densities and the energy velocities of the creeping waves. We used FILT (Fast Inversion of Laplace Transform) method for transient analysis. We compared the amplitudes of the creeping wave with that of steady state high frequency approximation obtained by the Watson transformation. The main results are: (1) We confirmed in the transient response that the pulse propagates clockwise and counterclockwise along the geodesic circumference. (2) In the transient electromagnetic field observed in the E-plane we can recognize creeping waves clearly. (3) The existence of creeping waves is not clear in the H-plane. (4) The pulse wave propagation on the sphere is seen more clearly from the Poynting vectors and the energy densities than the field components. (5) The energy velocity of the wave front is equal to the light velocity as should be. The energy velocity of the wave body becomes smaller with the passage of time. (6) The amplitude of the creeping wave for a beat pulse and the amplitude obtained by the Watson transform for mono spectrum agree in the order of relative error below 25%.

In this paper we review the recent progress and basic technology of vertical cavity surface emitting lasers together with related parallel surface operating optical devices. First, the concept of surface emitting lasers is presented, and then currently developed device technologies will be reviewed. We will feature several technical issues, such as multi-layer structures, 2-dimensional arrays, photonic integration, etc. Lastly, future prospects for parallel lightwave systems will be discussed.

We propose parallel rate-variable punctured convolutional coded PPM in photon communication to achieve high energy information efficiency Ie for desired bit error rate (BER) and transmission bandwidth. We theoretically show the BER performance, bandwidth expansion factor β and necessary Ie to achieve BER=10-6 of the proposed systems for some combinations of code rates. It is found that the proposed system can achieve high Ie for desired BER and β by selecting a suitable combination of code rates depending on the channel conditions. Moreover, it is shown that the proposed system has better BER performance than RS-coded PPM in the range of small β.

In this paper we study the problem of scheduling a tree-structured program on multiprocessors so as to minimize the total execution time, which includes communication delay between processors. It is assumed in the problem that a sufficiently large number of processors are available. It is known that if the program structures are restricted to be out-trees, the problem can be solved in O(n2) time, where n denotes the number of modules of a program. However, this problem is known to be NP-hard if the program structures are allowed to be in-trees. Up to now, no optimal algorithm, except an obvious one, was known for the latter case while some approximation algorithms were shown. We present an optimization algorithm with a nontrivial time bound O((1.52)nn log n) for the in-tree case.

We propose Polarization-Shift-Keying (POLSK) homodyne system using phase-diversity receivers and theoretically analyze its bit-error-rate (BER) performance. Since the proposed system uses polarization modulation and homodyne detection, it can cancel the phase noise and is attractive at a high bit-rate transmission. It is found that the receiver sensitivity of the proposed POLSK homodyne system is the same as that of POLSK heterodyne system and is much better than that of DPSK phase-diversity homodyne systems at high signal-to-noise ratio (SNR). We also cosider theoreically the effect of the fluctuation of state of polarization (SOP) on the BER performance of POLSK homodyne system.

We propose parallel rate-variable punctured convolutional coded PPM in photon communication to achieve high energy information efficiency Ie for desired bit error rate (BER) and transmission bandwidth. We theoretically show the BER performance, bandwidth expansion factor β and necessary Ie to achieve BER10-6 of the proposed systems for some combinations of code rates. It is found that the proposed system can achieve high Ie for desired BER and β by selecting a suitable combination of code rates depending on the channel conditions. Moreover, it is showm that the proposed system has better BER performance than RS-coded PPM in the range of small β.

The VSTEP concept and its practical application in the form of an LED-type pnpn-VSTEP demonstrating low power consumption through electro-photonic operational modes are both shown. Further, with focus primarily on the new laser-mode VSTEP with high-intensity light output and narrow optical beam divergence, the design features such as threshold gain and optical absorptivity, device fabrication, and characteristics are explained. The possibility of ultimate performance based mainly on electrical to optical power conversion efficiency, important from the application viewpoint of optical interconnection, are also discussed. Also, as two examples of functional optical interconnection achieved by VSTEP, serial-to-parallel data conversion and optical self-routing switches are shown. Finally, future opto-electronic technologies to be developed for two-dimensionally integrable surface-type optical semiconductor devices, including the VSTEP, are discussed.

We propose Polarization-Shift-Keying (POLSK) homodyne system using phase-diversity receivers and theoretically analyze its bit-error-rate (BER) performance. Since the proposed system uses polarization modulation and homodyne detection, it can cancel the phase noise and is attractive at a high bit-rate transmission. It is found that the receiver sensitivity of the proposed POLSK homodyne system is the same as that of POLSK heterodyne system and is much better than that of DPSK phase-diversity homodyne systems at high signal-to-noise ratio (SNR). We also cosider theoretically the effect of the fluctuation of state of polarization (SOP) on the BER performance of POLSK homodyne system.

In this paper we review the recent progress and basic technology of vertical cavity surface emitting lasers together with related parallel surface operating optical devices. First, the concept of surface emitting lasers is presented, and then currently developed device technologies will be reviewed. We will feature several technical issues, such as multi-layer structures, 2-dimensional arrays, photonic integration, etc. Lastly, future prospects for parallel lightwave systems will be discussed.

We consider applications of optical solitons to signal processing. Soliton switching devices promise ultrafast operation and compatibility with communications systems using optical pulses. Quantum soliton effects include broadband squeezing and quantum nondemolition measurements, and can reduce noise and increase sensitivities of optical measurements. We report the demonstration of two-color soliton switching and describe progress towards implementation of quantum nondemolition measurement of photon number using soliton collisions.

This paper concerns a subclass of regular languages, called strictly regular languages, and studies the problem of identifying the class of strictly regular languages in the limit from positive data. We show that the class of strictly regular languages (SRLs) is polynomial time identifiable in the limit from positive data. That is, there is an algorithm that, for any strictly regular language L, identifies a finite automaton accepting L, called a strictly deterministic finite automaton (SDFA) in the limit from positive data, satisfying the property that the time for updating a conjecture is bounded by O(mN2), where m is the cardinality of the alphabet for L and N is the sum of lengths of all positive data provided. This is in contrast with the fact that the class of regular languages is not identifiable in the limit from positive data.

Based on the semiclassical theory, we deduce the expressions of stimulated absorption, stimulated amplification and threshold by using density matrix equation in the Er3+-doped fibers. Meaningful results have been given and some phenomena occuring in experiments are explained theoretically.

This paper proposes a knowledge-based design method of a protocol of a communication network system based on the knowledge-based design methodology for computer communication systems. In the proposed method, two knowledge models, i.e., the communication network architecture model (CNAM) and the communication protocol architecture model (CPAM), are introduced and a protocol design task is modeled as a successive transformation process of these knowledge models. Giving CNAM which represents the users' requirements concerning a communication network system, the requirements specification of a protocol is derived from CNAM and represented as CPAM. Then, the detailed requirements specification of a protocol is also derived from CPAM and represented by the formal description technique (FDT-Expressions). The derivations of CPAM and FDT-Expressions are executed by the transformation rules which represent the mappings between knowledge models. Due to formally defined knowledge models and mappings, the proposed method provides a framework of a systematic support of knowledge-based protocol design. In this paper, the formal definitions of CNAM and CPAM are given, then the derivation process of FDT-Expressions of a protocol is also formalized based on these knowledge models. Furthermore, a design example is demonstrated by using LOTOS as one of the FDT-Expressions of a protocol.

This paper discusses new trends and directions in human interface (HI) technologies, and the effects of HI technologies on human life or on social activities. This paper postulates that the HI subsumes man-machine interface, human-computer interaction, human-human interaction, human-organizational interface, human-environmental interface, human-social interface, etc. A new communication model, called Human Interface Communication Model (HICOM), and a new human dialogue model, called Human Interface Dialogue model (HIDIM), are derived by reexamining trends and directions on HI technologies from the viewpoint of functional meanings of interfaces, and from the viewpoint of a socially distributed cognition mechanism.