Takine investigated the continuous time queueing system with single server and Markovian arrival streams (MAS) where service times of customers depend on the states of the underlying Markov chain immediately before and after arrivals and may differ from one another among streams. In this paper, we consider the discrete version of Takine's model. Since a MAS can be used to model the correlated traffics of several classes, we consider the discrete time queueing system with MAS as an input traffic. Moreover packets from different classes of traffic may require different service times. So service times of customers which are different from one another among streams and may depend on the states of the underlying Markov chain immediately before and after arrivals, are also considered. We obtain the distribution of the workload in the system using Neuts' matrix analytic method. Based on this result, we obtain the distributions of the actual waiting time and the sojourn time of a customer of each class and the joint distribution of the numbers of customers of each class. We also provide a recursion formula for computing the joint queue length distribution. We give an application to multimedia conference system and numerical example.

This paper deals with the wave scattering from a periodic surface with finite extent. Modifying a spectral formalism, we find that the spectral amplitude of the scattered wave can be determined by the surface field on only the corrugated part of the surface. The surface field on such a corrugated part is then expanded into Fourier series with unknown Fourier coefficients. A matrix equation for the Fourier coefficients is obtained and is solved numerically for a sinusoidally corrugated surface. Then, the angular distribution of the scattering, the relative power of each diffraction beam and the optical theorem are calculated and illustrated in figures. Also, the relative powers of diffraction are calculated against the angle of incidence for a periodic surface with infinite extent. By comparing a finite periodic case with an infinite periodic case, it is pointed out that relative powers of diffraction beam are much similar in these of diffraction for the infinite periodic case.

We propose a new detection method of a 2-dimensional pH image to measure the pH distribution of test materials by illuminating a frequency modulated light to LAPS using a chopping wheel. It could simultaneously measure signals in one line by applying a modulated light with a different frequency for each pixel, using a chopping wheel for modulating the frequency, and calculating an amplitude with respect to a frequency component by the light source. To test the proposed method, we implement a chopping wheel in consideration of a LAPS's characteristic, and reconstructed an image by frequency analysis using the implemented chopping wheel and 4 mm test pattern image. As a result, we verified that the proposed method using the chopping wheel was able to detect 30 times faster a 3030 pixels pH image having a PSNR more than 22 dB above the conventional method.

Gnutella's service announcement in March 2000 stirred worldwide interest by referring to P2P model. Basically, the P2P model needs not the broker "the centralized management server" that until now has figured so importantly in prevailing business models, and offers a new approach that enables peers such as end terminals to discover out and locate other suitable peers on their own without going through an intermediary server. It seems clear that the wealth of content made available by peer-to-peer systems like Gnutella and Freenet have spurred many authors into considering how meta-data might be used to support more effective search in a distributed environment. This paper has reviewed a number of these systems and attempted to identify some common themes. At this time the major division between the different approaches is the use of a hash-based routing scheme.

This paper describes an analysis of the electromagnetic interference (EMI) aspects of electrostatic discharge (ESD), which sometimes causes serious damage to electrical systems. To classify EMI-related properties resulting from ESD events, we used a self-organizing neural network, which can map high-dimensional data into simple geometric relationships on a low-dimensional display. Also, to clarify the effect of a high-speed moving discharge, we generated one-shot discharges repeatedly and measured the ESD current in the time domain to obtain its EMI-related characteristics of this phenomenon. Based on the measured data, we examined several differential properties of ESD waveforms including the maximum amplitude and energy level, and analyzed these multi-dimensional data using the self-organizing neural network scheme. The results showed that the high-speed moving discharges can increase the maximum amplitude, relative energy, and entropy of ESD events, and that the positioning of the EMI level of each ESD event can be effectively visualized in a two-dimensional space.

This letter introduces a chaotic circuit consisting of one linear 2-port VCCS, one hysteresis 2-port VCCS, and two capacitors. The circuit has double screw attractors, quad screw attractors and co-existence states of them. Since the system is piecewise linear, attractors existence condition can be described using exact piecewise solutions. Using a simple test circuit, typical phenomena are verified in the laboratory.

A simple configuration for millimeter-wave fiber-wireless transmission, with remote local-oscillator (LO) delivery from the central office, both for the uplink and for the downlink, and a simple, cost-effective, base-station solution is proposed. Under the assumption of using commercially available components and a conventional single-mode fiber (with dispersion of 17 ps/nm/km at 1.55 µm), our numerical results show that, with a laser linewidth of 150 MHz, a laser power of 0 dBm and an optical gain of only 6 dB, it is possible to transmit, without repeaters, data rates of 622 Mbit/s across about 18 km at a bit-error-rate of 10-9. By increasing the optical gain to 24 dB, the link length can be increased to approximately 67 km for a laser linewidth of 75 MHz and to 78 km for a laser linewidth 1 MHz.

Two implementation schemes for a two-step SOVA (Soft Output Viterbi Algorithm) decoder are proposed and verified in a chip. One uses the combination of trace back (TB) logic to find the survivor state and double trace back logic to find the weighting factor of a two-step SOVA. The other is that the reliability values are divided by a scaling factor in order to compensate for the distortion brought by overestimating those values in SOVA. We introduced a fixed scaling factor of 0.25 or 0.33 for a rate 1/3 and designed an 8-state Turbo decoder with a 256-bit frame size to lower the reliability values. The implemented architecture of the two-step SOVA decoder allows important savings in area and high-speed processing compared with the one-step SOVA decoder using register exchange (RE) or trace-back (TB) method. The chip is fabricated using 0.65 µm gate array at Samsung Electronics and it shows higher SNR performance by 2 dB at the BER 10-4 than that of a two-step SOVA decoder without a scaling factor.

A new fuzzy logic-based buffer management scheme (BMS) called fuzzy early detection (FED) is presented to improve transmission control protocol (TCP) performance over the unspecified bit rate (UBR) service of asynchronous transfer mode (ATM) networks. FED uses early congestion detection and selective packet discard (ECD/SPD) strategies to achieve its design goals, and adopts early packet discard (EPD) to prevent frequent buffer overflows. Two variants of FED are constructed for comparison purposes. FED performance is then evaluated against those of its variants, pure EPD and P-random early detection (P-RED) through various simulations. The effects of TCP implementation, TCP maximum segment size (MSS), network's propagation delay (PD) and switch buffer size (SBS) on their performances are studied. The overall result shows that FED is superior to the other BMSs when the criteria of efficiency, fairness, scalability and switch buffer requirement are considered collectively.

In this paper, we present a design of MPEG-4 video codec chip to reduce the power consumption using frame level clock gating, macro block level and motion estimation skip scheme. It performs 30 frames/s of codec (encoding and decoding) mode with quarter-common intermediate format (QCIF) at 27 MHz. Power consumption is 290 mW at 27 MHz operation, which is achieving 35% power saving compared to a conventional CMOS. Motion Estimation skip method is employed to reduce 32% computation load. This chip performs MPEG-4 Simple Profile Level 2 (Simple@L2) and H. 263 base mode. Its contains 388,885 gates, 662 k bits memory, and the chip size was 9.7 mm9.7 mm which was fabricated using 0.35 micron 3-layers metal CMOS technology.

The authors have been interested in a Scanning Laser Microscope (SLM) and applied it to studies of contact phenomena. In particular, a digital SLM is being currently used, and confirmed to be a successful tool for investigating the contact phenomena. In this paper, the theory and mechanism of a digital SLM are briefly explained, and some actual data obtained with the digital SLM are presented for demonstrating its usefulness for studies of contact phenomena.

This paper describes two methods to construct fuzzy inference rules by the simplified fuzzy reasoning. The present methods have a construction mechanism of the rule unit that is applicable in two parameters: the central value and the width of the membership function in the antecedent part. The first approach is to create a rule unit near the selected rule which has the nearest position from the central input space for the central value. The second is to create a rule unit near the selected rule which has the minimum width for the width. Experimental results are presented in order to show that the proposed methods are effective in difference on the inference error and the number of learning iterations.

The authors study the performance of a disk storing WWW data by using a broadcast polling model. The model has single message queues, an exponential server and asymmetric exponential arrivals. Numerical examples show that the analytical results are close to the simulation results.

An experimental equation of V-I characteristics of breaking arc was investigated in the air at atmospheric pressure. Material of the contact pair is Ag, Au, Cu and Ni. Supply voltage is set to 42, 48 and 54 V. The electrical resistance of experimental circuit is 5 Ω. The time evolutions of arc voltage, arc current and gap length were measured, simultaneously. V-I characteristics were obtained from those measured values. The dependence of the arc voltage on the gap length was represented by an approximate formula as a straight line in order to obtain the experimental equation. And the dependence of the strength of electric field of arc column on the supply voltage was approximated to a straight line. Using these approximate formulae, the experimental equation of the dependence of the arc voltage on the arc current was obtained with the gap length as a parameter. It was shown that the experimental equation agreed with experimental data in the experimental conditions for each contact material.

AgCdO12wt% contacts mounted on electromagnetic relays are tested in a DC 42 V-8.4 A resistive circuit as make-only contacts and break-only contacts. In this experiment, the arc duration has been measured for each operation and the shape of the transferred pip on each contact has been observed using photograph records taken every 1000 operations. The transferred pip grows markedly at make-only contacts. Furthermore, as a few samples with the long arc duration have the flat hill transferred from the cathode on the anode surface of break-only contacts, we believe that the transferred direction reverses at a certain arc length.

We can easily access a remote database as well as a local database with HTML forms. Although implementing a database application with HTML forms is much simpler than implementing it with a proprietary graphical user-interface system, HTML forms and CGI programs still must be coded. We implemented a software tool that automatically generates the SQL statements that create a database for an application, the forms that are used as a user interface, and the Java servlets that retrieve the data requested through the forms. The database tables to be created and the forms to be generated are determined by the class diagram for the application. Our software tool, which we call WebSiteGen, thus simplifies the implementation of a Web-based database application.

A broadband access network is required for supporting the increased Internet data traffic. One of the most cost-effective solutions is the Ethernet Passive Optical Networks (E-PONs) with the efficient bandwidth assignment function by which the upstream bandwidth can be shared among access users. To satisfy the services with heterogeneous QoS characteristics, it is very important to provide QoS guaranteed network access while utilize the bandwidth efficiently. In this paper, a dual DEB-GPS scheduler in E-PON is presented to provide delay-constraint and lossless QoS guarantee to QoS service and maximize the bandwidth to best-effort service. Simulation results show our scheme outperforms the conventional bandwidth allocation scheme in E-PON system.

Mathematical analysis of the average behavior of the AVL balanced tree insertion algorithm has not ever been done completely. As the first step toward this analysis, we have proposed an approximate analysis based on the assumption that all AVL balanced trees with a given number of nodes and height are constructed with equal probability. In this paper, we propose a new analysis of the AVL balanced tree insertion algorithm in conformity with that all n! permutations of n keys occur with equal probability. First we derive the formulae to enumerate the number of permutations constructing the AVL balanced trees with a given number of nodes and height. Then, we propose the formulae to evaluate the average behavior of the AVL balanced tree insertion algorithm and show some results from the proposed formulae.

In a bidirectional wavelength-reused system, polarization control is used to reduce power penalty induced by coherent mixing of the signal with Rayleigh backscattering. The reduction of the effect of Rayleigh backscattering is theoretical study and experimental demonstration. For a 50km, 10Gb/s bidirectional transmission system, an error floor of about 510-10 under the worst polarization state is occurred. Nevertheless, the power penalty is reduced from 3.5dB to only 0.3dB when the signals are under optimum polarization control. The results indicate that the proposed technique may find vast applications in bidirectional ring networks with add/drop as well as cross-connect nodes using wavelength-reused technology.

The linear hashing is a well-known dynamic hashing algorithm designed for internal main memory as well as external secondary memory. Traditional analysis of this search algorithm has been proposed under the assumption that all keys are uniformly accessed. In this paper, we present a discrete analysis of the average search cost of the linear dynamic hashing algorithm for internal main memory in consideration of the frequency of access on each key. In the proposed discrete analysis, the number of probes itself is regarded as a random variable and its probability distribution is derived concretely. Furthermore, the evaluate formula derived from the proposed analysis can exactly evaluate the average search cost in conformity with any probability distribution of the frequency of access. The proposed analysis is compared to the traditional one provided that the frequency of access on each key is uniform, and the differences are discussed.