In the paper a new type of Multilayer Perceptron, developed in Quaternion Algebra, is adopted to realize short-time prediction of chaotic time series. The new introduced neural structure, based on MLP and developed in the hypercomplex quaternion algebra (HMLP) allows accurate results with a decreased network complexity with respect to the real MLP. The short term prediction of various chaotic circuits and systems has been performed, with particular emphasys to the Chua's circuit, the Saito's circuit with hyperchaotic behaviour and the Lorenz system. The accuracy of the prediction is evaluated through a correlation index between the actual predicted terms of the time series. A comparison of the performance obtained with both the real MLP and the hypercomplex one is also reported.

From a GF(q) sequence {ai}i0 with period qn - 1 we can obtain new periodic sequences {ai}i0 with period qn by inserting one symbol b GF(q) at the end of each period. Let b0 = Σqn-2 i=0 ai. It Is first shown that the linear complexity of {ai}i0, denoted as LC({ai}) satisfies LC({ai}) = qn if b -b0 and LC({ai}) qn - 1 if b = -b0 Most of known sequences are shown to satisfy the zero sum property, i.e., b0 = 0. For such sequences satisfying b0 = 0 it is shown that qn - LC({ai}) LC({ai}) qn - 1 if b = 0.

A method is presented for detecting impulsive noises in chaotic time series, based on a new nonlinear prediction algorithm. A multi-dimensional trajectory is reconstructed from a time series using delay coordinates. The future value of a point on the trajectory is predicted using a local approximation technique revised by adding the Biweight estimation method and then the prediction error is calculated. Impulsive noises are detected by examining the prediction errors for all points on the trajectory. The proposed method is applied to the time series of the pupil area and the refractive power of the lens in the human eye. The Lyapunov exponent analysis for thses time series is conducted. As a result, it is shown that the proposed method is effective in detecting impulsive noises caused by blinking in these time series.

The Guaranteed Bandwidth Protocol (GBW) is an access scheme being proposed for implementation of connection oriented services in DQDB networks. Connection oriented services are expected to handle both constant bit rate (CBR) and variable bit rate (VBR) traffic that have delay and jitter constraints. It has been reported that the GBW protocol can provide guaranteed bandwidth and lower delays compared to the ordinary DQDB protocol. However, the intensity of the jitter introduced by this scheme has not been made clear. This paper compares the jitter results for the GBW scheme to those obtained by a new access method called Modified Guaranteed Bandwidth (MOD_GBW) protocol, which is proposed here. It is shown through simulation that MOD_GBW also provides guaranteed bandwidth and that its delay and jitter characteristics are significantly better than those of the GBW protocol. In the simulation model, the DQDB stations are divided into two groups: 1)Real-Time (RT) stations that generate either CBR or VBR real-time traffic; and 2)Data stations that generate memoryless type of traffic. Data stations operate according to the ordinary DQDB protocol only. The main performance measure adopted here for the real-time traffic is the interdeparture time distribution of consecutive segments from an RT-station. We define the variance of this distribution as jitter. This paper also shows the impact of GBW/MOD_GBW on the performance of the data stations by evaluating their throughput and average bus access delay. Finally, we show that the network performance is weakly related to the number of RT-stations under MOD_GBW, but it depends strongly on the overall loading.

The thermal and/or the tensile strain distribution along the fiber make the Brillouin gain coefficient different in each point of the fiber. As a basic study of the Brillouin fiber optic gyro, its effect on lasing characteristics of a fiber Brillouin ring laser is formulated in the general form by using the statistical function and then calculation is done for typical values of the parameters. By suppressing the polarization-fluctuation-induced noise caused by the temperature, an example of the effect of the spatially distributed gain coefficient is experimentally demonstrated.

This study clarifies the effects of network complexity and network map transformation on the ability of network managers to use graphic network displays. Maps of Japan and the United States with outlines of their respective prefectures or states were displayed on a CRT. Each map displayed a fictitious network of nodes and their interconnections. These networks were two-level hierarchical and non-meshed, meaning that each low-level node was connected to a single high-level node, but not all high-level nodes were linked together. The subjects, task was to identify a path between two low-level nodes. In each trial, two low-level nodes were highlighted, and the subject attempted to find the shortest path between these nodes. This was done by using a mouse to select intermediate nodes. Completing a path required a minimum of 4 node traversals. Three variables were manipulated. First, the number of nodes was defined as the total number of low-level nodes in a network (70, 150, or 200). The second variable was the level of transformation. Very densely populated areas of the maps were systematically transformed to reduce congestion. There were three levels of transformation. The final variable was the country map used, that is, the map of Japan and the map of the United States. Several behavioral measures were used. The most informativ. appeared to be the time required to complete a path (the response time), and how often subjects returned to previous portions of a path (back-ups). For both of these measures, the data pattern was essentially the same. Increasing the number of nodes hurts performance. This was particularly pronounced when the map of Japan was tested. However, as the level of transformation increased, this effect was substantially reduced or completely eliminated. The results are discussed in terms of engineering rules and guidelines for designing graphical network representations.

A close correlation between the YBa2Cu3Oy film morphology and location of the (100) MgO substrate during growth by excimer laser ablation was obtained. When the susbtrate was placed inside the fringe portion of the laser plume, the spiral shape was most clearly seen on the entire film surface for both the conventional and eclipse ablation methods. When the substrate was placed outside the plume, the spiral growth was less pronounced. On the other hand, when the substrate was placed inside the plume core, marked deformation of the morphology occurred, and the superconducting critical temperature was lowered. This correlation was explained to some extent by the spatial variation of kinetic energy of the flying growth species.

For the dependent protocols to perform the server-aided RSA secret computation, the damage caused by the active attacks is greater than that by the passive attacks. Though there are two dependent proposed protocols against active attacks, the cost of the two protocols is still high. In this paper, we propose two efficient dependent protocols. Even considering the low cost of these two protocols, they can also guard against the proposed active attacks.

This paper proposes and investigates the adaptive multi-user equalizer based on the multi-dimensional IIR adaptive lattice filter in order to suppress the co-channel interference (CCI) in asynchronous DS/CDMA system. An asynchronous DS/CDMA system with multi-user receiver is modeled as multi-dimensional or multi-input/out system with cross-coupling that is co-channel interference. From the system model it is shown that the multi-user detection is reduced into a problem of multi-dimensional equalization for multiaccess interference as well as intersymbol interference. The proposed multi-user equalizer can improve the equalizing error of the filter, comparing with that of the multi-dimensional FIR transversal filter of which number of tap is finite. The multi-dimensional lattice filter can adaptively achieve fast and stable convergence with less taps. Since the filter can resolve correlative multiple input into orthogonal output stage by stage, CCI can be removed. Computer simulations show performance of the proposed scheme.

The 4th harmonics of a Nd:YAG laser beam (266 nm) is applied to fabricate highly oriented Y1Ba2Cu3O7-δ -SrTiO3-Y1Ba2Cu3O7-δ multilayer structures. It has been shown that the emission temperature of a film surface will change during deposition, depending on deposition conditions, even though the heater temperature is constant. The change of substrate temperature is strongly correlated to film characteristics such as critical temperature, c-axis length, and resistivity. The insitu monitoring of the substrate temperature is useful for obtaining high-quality Y1Ba2Cu3O7-δ films reproducibly. It is also shown that a SrTiO3 layer prevents oxygen restoration in a Y1Ba2Cu3O7-δ underlayer. The relationship between oxygen deficiency and the annealing conditions is studied.

Viterbi decoding is known as a decoding scheme that can realize maximum likelihood decoding. However, it is impossible to continue it without re-synchronization even if only an insertion/deletion error occurs in a channel. In this paper, we show that Levenshtein distance is suitable for the metric of Viterbi decoding in a channel where not only symbol errors but also insertion/deletion errors occur under some conditions and we propose a kind of Viterbi decoding considering insertion/deletion errors.

We proposed a graphical user interface (GUI) that provides users with multimedia information, including dynamic images. On the Internet, there are many WWW browsers that read the Hypertext Markup Language (HTML). As various browsers extend the HTML tags and attributes independently to expand and/or improve layout, the HTML compatibility between browsers is lost. We have developed a WWW browser to solve this problem. Our browser presents all multimedia information, including text, images, and dynamic images as a block and renders them without the need to extend the HTML specifications. It independently interprets and draws HTML objects using a layout manager. It has a layout rule, and manages the hierarchical data structure and the block data of HTML documents. This browser also allows layout-rule changes. The layout manager efficiently displays information while checking the available display area size. The structure of this browser is such that the portion that manages the formatting of the document is separated from the portion that displays the individual parts. In this browser, the layout rule allows text to be placed around an image without the need to modify the existing HTML contents. It is also relatively easy to change the presentation of multiple screens, such as a two-page book-like layout or the conventional single-page scroll-bar format by changing the layout rule. The incorporation of media decoders into the browser enables the displaying of various multimedia information, such as sounds, pictures, and moving images.

We develop a simulation environment for designing and examining a neural network model at the network level. The aim of our research is to enable researchers investigating neural network connective models to save time by being equipped with a graphical user interface and database of the network models. This environment consists of three parts: (1) the kernel of the simulation system, (2) NNDBMS (Neural Networks DataBase Management System), and (3) a system for displaying simulation results in various ways.

In this paper, we present a distributed RAID style video server that addresses the problem of increasing video stream supplying capability in VOD systems. Distibuted RAID Stylemeans extending the RAID method usually applied to disks to the servers, so as to achieve improvements in performance and reliability. The great advantage of this architecture is that the linear performance improvement can be achieved by adding inexpensive servers of a diffusion model. We have implemented the RAID0 style and RAID4 style systems. A number of new features such as the array configuration method or the striping buffer are applied to them. A precise performance evaluation was made in a near practical environment, with more than 40 video streams. We tested the system, in both normal and degraded mode (server failure) and by checking frame drop rates as well as observing picture quality. An evaluation by simulation was also conducted. The results of the above evaluations agreed well with the calculation value, to confirm the feasibility of this architecture.

This paper presents the system issues involved with the transmission of pre-encoded VBR MPEG video using CBR service. Conventional wisdom suggests that lossless delivery of VBR video using CBR service requires bandwidth to be reserved at the peak rate resulting in low bandwidth utilization. We calculate the minimum rate at which bandwidth must be reserved on a network in order to provide continuous playback of an MPEG encoded video bitstream. Simulation results using the frame size traces from several pre-encoded MPEG bitstreams and several buffer sizes demonstrate that this minimum reservation rateis much lower than the peak rate when a relatively small playback buffer size is used, resulting in much higher bandwidth utilization. Procedures for performing connection setup and lossless realtime video playback between the video server and the client are outlined. Methods for incorporating VCR-like features such as pauseandfast forward/reversefor Video-on-Demand (VoD) applications are presented.

This paper describes a trial of evaluating the proper characteristics of multiple sound insulatain systems from their output responses contaminated by unknown background noises. The unknown parameters of sound insulation systems are first estimated on the basis of hte linear time series on an intensity scale, describing functionally the input-output relation of the systems. Then, their output probability distributions are predicted when an arbitrary input noise passes through these insulation systems.

The evolution of access networks towards Fiber-To-The-Home (FTTH) receives much attention throughout the world because FTTH has a big potential for providing future attractive services. To provide such services in terms of transmission rate, the cable network transition scenario from conventional copper cable network to optical fiber cable one in access field should be clarified. Since network transition scenario deeply depends on the service evolution scenarios (what type of service would appear at a certain time and how many customers move to the other services, for example), this paper firstly categorizes telecommunication services into four kinds of services, i.e. Basic Service (e.g. POTS), Narrowband Symmetrical Service (e.g. NISDN), Broadband Asymmetrical Services (e.g. Video-On-Demand) and Broadband Symmetrical Services (e.g. BISDN) in terms of up-and down-stream transmission rates. Based on this service categorization, it is proposed to formalize service evolution scenarios by a transition pattern of the initial demands and the penetration rates of these services. Then, the evaluation method of network transition scenarios is also proposed in terms of NPV by the service evolution scenarios. It is conclude that the network transition scenarios are deeply related to the amount and behavior of the demands moving to the other services as follows.-The scenario where the new system configuration partly replaces the old one whenever the demands appear for providing higher transmission rate services is applicable, when the demands move little or constantly move to the higher transmission rate services,-The scenario where the new system configuration totally replaces the old one at the early stage for providing all services is applicable, when the demands drastically move to the higher transmission rate services during short period.

In this paper, we present an exact analysis and an efficient matrix-analytic procedure to numerically evaluate the performance of cellular mobile networks with hand-off. In high-capacity micro-cell cellular radio communication networks, a cell boundary crossed by moving users can generate many hand-off attempts. This paper considers such a priority scheme that some channels and buffers are reserved for hand-off calls to reduce the forced termination of calls in progress. Performance characteristics we obtained include blocking probability, channel utilization, average queue length and average waiting time for hand-off calls. Using the matrix-analytic solution for the stationary state probability distribution, we also derive the probability distribution of the waiting time of a hand-off call. Numerical results show how priority can be provided to hand-off calls according to the number of reserved channels and buffer size. They also clarify the effect of the hand-off priority scheme on the standard deviation of waiting time of a hand-off call.

In this paper, a feasible optical code-division multiple-access (CDMA) technique is proposed for high-speed computer networks using prime codes and optical signal processing to guarantee real-time data communications. All-optical architectures for fastly tunable CDMA encoders and decoders are presented, which can be feasibly implemented in the optical domain by using electrooptic switches and optical delay lines. This can support an ultrahigh throughput and a very fast reconfiguration time. Furthermore, we present a self-synchronized sample technique to ensure the correct phase synchronization between optical clock stream and asynchronous electronic data at each electrooptic modulator of an optical CDMA transmitter.

A new multi-functional card with a display, sounder and input keys, and related communication equipment, including a microwave base station and a contactless surface reader/writer, have been developed to perform the functions of positioning, paging, returning a message and identity certification. We confirmed that a prototype subsystem was capable of providing a simple and automatic call forwarding service. The multi-functional card as an ID card and a personal data terminal, and its subsystem can provide new personal services for a multimedia office.