Software rejuvenation is a proactive fault management technique that has been extensively studied in the recent literature. In this paper, we focus on an example for a telecommunication billing application considered in Huang et al. (1995) and develop the discrete-time stochastic models to estimate the optimal software rejuvenation schedule. More precisely, two software availability models with rejuvenation are formulated via the discrete semi-Markov processes, and the optimal software rejuvenation schedules which maximize the steady-state availabilities are derived analytically. Further, we develop statistically non-parametric algorithms to estimate the optimal software rejuvenation schedules, provided that the complete sample data of failure times are given. Then, a new statistical device, called the discrete total time on test statistics, is introduced. Finally, we examine asymptotic properties for the statistical estimation algorithms proposed in this paper through a simulation experiment.

We developed a SPARC-V9 processor, the SPARC64 V. It has an operating frequency of 1.35 GHz and contains 191 million transistors fabricated using 0.13-µm CMOS technology with eight-layer copper metallization. SPECjbb2000 (CPU# 32) is 492683, highest on the market and 42% higher than the next highest system. SPEC CPU2000 performance is 858 for SPECint and 1228 for SPECfp. The processor is designed to provide the high system performance and high reliability required of enterprise server systems. It is also designed to address the performance requirements of high-performance computing. During our development of several generations of mainframe processors, we conducted many related experiments, and obtained enterprise server system (EPS) development skills, an understanding of EPS workload characteristics, and technology that provides high reliability, availability, and serviceability. We used those as bases of the new processor development. The approach quite effectively moves beyond differences between mainframe and SPARC systems. At the beginning of development and before the start of hardware design, we developed a software performance simulator so we could understand the performance impacts of created specifications, thereby enabling us to make appropriate decisions about hardware design. We took this approach to solve performance problems before tape-out and avoid spending additional time on design update and physical machine reconstruction. We were successful, completing the high-performance processor development on schedule and in a short time. This paper describes the SPARC64 V microprocessor and performance analyses for development of its design.

In this paper we present an unsupervised color image segmentation algorithm based on statistical models. We have adopted the Gaussian mixture model to represent the distribution of color feature vectors. A novel deterministic annealing EM and mean field theory from statistical mechanics are used to compute the posterior probability distribution of each pixel and estimate the parameters of the Gaussian Mixture Model. We describe the noncontexture segmentation algorithm that uses a deterministic annealing approach and the contexture segmentation algorithm that uses the mean field theory. The experimental results show that the deterministic annealing EM and mean field theory provide a global optimal solution for the maximum likelihood estimators and that these algorithms can efficiently segment the real image.

In this paper, we propose the soft boundary concept achieved by dynamic tilted antenna to solve the issue of traffic congestion occurred in cellular wireless systems. The tilted antenna array can provide the merit of traffic balance and also achieve the optimization of the signal-to-interference ratio (SIR) at receivers by automatically tilting the antenna and implementing the soft boundary among cells, corresponding to the variation of traffic. According to our results, it is shown that power ratio control do not necessarily improved system performance when there is a large variation in traffic because it only control power levels. Also the properly chosen angle of tilt antenna can relieve the traffic congestion and perform the system performance optimization.

A novel effective method for detection and removal impulse noise in highly corrupted color images is proposed. This detection-estimation method consists of two steps. Outliers are first detected using spatial relations between the color components. Then the detected noise pixels are replaced with the output of the vector median filter over a local spatially connected area excluding the outliers. Simulation results in a test color image show a superior performance of the proposed filtering algorithm comparing to the conventional vector median filter. The comparisons are made using a mean square error and a mean absolute error criteria.

This paper presents two different algorithms for random number generation. One algorithm generates a random sequence with an arbitrary distribution from a sequence of pure random numbers, i.e. a sequence with uniform distribution. The other algorithm generates a sequence of pure random numbers from a sequence of a given i.i.d. source. Both algorithms can be regarded as an implementation of the interval algorithm by using the integer arithmetic with limited precision. We analyze the approximation error measured by the variational distance between probability distributions of the desired random sequence and the output sequence generated by the algorithms. Further, we give bounds on the expected length of input sequence per one output symbol, and compare it with that of the original interval algorithm.

The application of Elliptic Curve Cryptosystem has gained more and more attention. ECC uses smaller key size and lower memory requirement to retain the security level and can be a crucial factor in the smart card system. In this paper, an ECC based implementation of security schemes in smart card system to access control the door of some confidential places is proposed. The confidential place, for example a coffer, a strong room in the bank is used to store treasures as well as cashes, and where the mutual vigilance could be required. For the safety consideration, the going in and out a coffer by a person is not permissive but a group of authorized people. It involves the problem of secret sharing. The adopted solution of sharing secret is threshold scheme. Every participant possesses a secret shadow, which will be saved in the smart card. After correct reconstructing the shared secrets, it is permissible to access the coffer's door. For resisting dishonest participants, cheating detection and cheater identification will be included. The user can change his password of smart card freely and need not memorize his assigned lengthy password and shadow as traditional ID-based schemes makes our implementation much more user friendly.

Field Configurable Self-assembly is a novel programmable force field based heterogeneous integration technology. Herein, we demonstrate application of the method to rapid, parallel assembly of similar and dissimilar sub-200 µm GaAs-based light emitting diodes at silicon chip substrates. We also show that the method is compatible with post-process collective wiring techniques for fully planar hybrid integration of active devices.

Automatic image inspector inspects the quality of printed circuit boards using image-processing technology. In this study, we change an automatic inspection problem into a problem for detecting the signal singularities. Based on the wavelet theory that the wavelet transform can focus on localized signal structures with a zooming procedure, a novel singularity detection and measurement algorithm is proposed. Singularity positions are detected with the local wavelet transform modulus maximum (WTMM) line, and the Lipschitz exponent is estimated at each singularity from the decay of the wavelet transform amplitude along the WTMM line. According to the theoretical analysis and computer simulation results, the proposed algorithm is shown to be successful for solving the automatic inspection problem and calculating the Lipschitz exponents of signals. These Lipschitz exponents successfully characterize singular behavior of signals at singularities.

This report describes face image recognition by 2-dimensional discrete Walsh transform and multi-layer neural networks. Neural network (NN) is one of the powerful tools for pattern recognition. In the previous researches of face image recognition by NN, the gray levels on each pixel of the face image have been used for input data to NN. However, because the face image has usually too many pixels, a variety of approaches have been required to reduce the number of the input data. In this research, 2-dimensional discrete Walsh transform is used for reduction of input data and the recognition is done by multi-layer neural networks. Finally, the validity of our method is varified.

Rate control regulates the coded bit stream to satisfy certain given bit rate condition while maintaining the quality of coded video. However, most existing rate control algorithms for low bit rate video can not handle scene change properly, so visual quality is consequently worsened. The test model TMN8 of H.263+ can be forced to skip frames after an abrupt scene change. In this letter, we propose a new frame-layer rate control which allocates bits to frames and controls the frame skipping adaptively based on the pre-analysis of future frames. Experimental results show that the proposed control method provides an effective alternative to existing frame skipping methods causing the motion jerkiness and quality degradation.

Relative time-stamping schemes prove the chronological sequence of digital documents and their integrity. Since the chronological sequence is verified by tracing the link between two timestamps, it is desirable that the length of the verification path is short. Buldas, Laud, Lipmaa, and Villemson have proposed the relative time-stamping scheme based on the binary link. In this paper, we extend the binary link to the ternary link, and apply it to the relative time-stamping scheme. We show that the maximum length of the verification path of the proposed scheme is shorter than that of the previous scheme. Moreover, we show that the average length of the proposed scheme is shorter than that of the previous scheme. Thus, the proposed time-stamping schemes is more efficient than the previous scheme.

The history of the development of the High Electron Mobility Transistor (HEMT) is an outstanding illustration of how a new device can be successfully marketed. In this paper we discuss a key to successful commercialization of new devices.

In digital content distribution systems, digital watermarking (fingerprinting) technique provides a good solution to avoid illegal copying and has been studied very actively. c-Secure CRT Code is one of the most practical ID coding schemes for such fingerprinting since it is secure against collusion attacks and also secure even though random errors are furthermore added. But its usefulness is decreased in the case that random errors are added because the code length will be longer. In this paper, a new collusion attack with addition of random errors is introduced and show that c-Secure CRT Code is not sufficiently secure against the attack at first. Next, we analyze the problem and propose a new ID coding scheme, Randomized c-Secure CRT Code which overcomes the problem. As a result, this new scheme improves the error tracing probabilities against the proposed attack drastically. This new scheme has the same code length, so this is one of the most responsible fingerprinting codes for content distribution systems.

Beam-space time coding methods are being extensively investigated, since they provide levels of performance appropriate for the next and future generations of wireless communication systems. In this paper, we focus on beam-domain space-time coding, especially considering the case when transmit beams have inter-beam interference (IBI). A new beam-space time coding scheme that takes into account the overlap amount among beams is proposed. We observe that the overlap of beams introduces an amount of correlation to the channels in a similar way to the well-known Partial Response (PR) channel in magnetic recording. Based on that observation, the proposed system can make use of IBI to encode and decode the signals. We evaluate the proposed system both via theoretical upper bound and via computer simulations. The Bit Error Rate (BER) performance of the proposed system using IBI is better than that of the system with no-IBI because the proposed system delivers more coding gain. However, the overlap of beams decreases the diversity gain. The tradeoff relationship between diversity gain and coding gain is investigated.

High-temperature stability of copper (Cu) gate AlGaN/GaN high electron mobility transistors (HEMTs) was investigated. Samples were annealed at various temperatures to monitor the changes on device performances. Current-voltage performance such as drain-source current, transconductance, threshold voltage and gate leakage current has no obvious degradation up to annealing temperature of 500 and time of 5 minutes. Also up to this temperature, no copper diffusion was found at the Cu and AlGaN interface by secondary ion mass spectrometry determination. At annealing temperature of 700 and time of 5 minutes, device performance was found to have degraded. Gate voltage swing increased and threshold voltage shifted due to Cu diffusion into AlGaN. These results indicate that the Schottky contact and device performance of Cu-gate AlGaN/GaN HEMT is stable up to annealing temperature of 500. Cu is a promising candidate as gate metallization for high-performance power AlGaN/GaN HEMTs.

Web Services (WS) have received significant attention recently. Delivering Quality of Service (QoS) on the Internet is a critical and significant challenge for WS community. This article proposes a Web Services Testing Framework (WSTF) for WS participates to perform WS testing. WSTF provides three main distributed components: test master, test agents and test monitor. Test master manages scenarios and generates test scripts. It initiates WS testing by sending test scripts to test agents. Test agents dynamically bind and invoke the WS. Test monitors capture synchronous/asynchronous messages sent and received, attach timestamp, and trace state change information. The benefit to use WSTF is that the user only needs to specify system scenarios based on the system requirements without needing to write test code. To validate the proposed approach, this paper used the framework to test a supply-chain system implemented using WS.

To meet the highly competitive and dynamic needs in the market, an e-Business company needs to flexibly integrate its heterogeneous database systems together, e.g., the integration of makers and retailers in a Supply Chain Management System (SCM). The customers demand one-click response and also their access requirements change too frequently. Moreover, different retailers and makers in a SCM, being the autonomous entities, have their own specific requirements for stock-cost and opportunity-loss, depending on their local situation that is also changing with time. Under this background, the integrated DBs of the SCM are required to provide real-time response, heterogeneity satisfaction and flexibility to adapt to changing requirements. The conventional approach of strict consistency leads to low response and less flexibility due to the strong interdependence of the systems. In this paper, Autonomous Decentralized Database System has been proposed as an application-oriented database technology based on the concept of autonomy and loose-consistency among the distributed DB systems thus providing real-time, flexibility and high availability. The autonomy in the system has been achieved by defining a data attribute, Allowable Volume, within which each component DB has autonomy to update the data in real-time. Moreover, the system adapts to the dynamically changing heterogeneous access requirements at each DB by managing the distribution of AV among different DBs through an active coordination mechanism. Due to the dynamic and unpredictable environment, the component DBs are provided with complete autonomy for their local and coordination decisions, thus diminishing the interdependency and improving the response time. As the system consists of loosely-connected subsystems, it also has high availability. Therefore, the proposed system provides highly decentralized architecture with flexibility and high availability. The performance of the system has been shown significantly effective by simulating the internet based SCM system, from the communication-cost and response time point of view.

Software and its systems are more complicated than a decade ago, and the systems are used for mission critical business, flight control and so on which often require high assurance systems. In this circumstance, we often use black-box testing. The question now arises that black-box testing does not generate numerical value of testing result but empirical. Thus, in this research, we develop and enhance FSM (Finite State Machine) testing method which can produce code coverage rate as numerical value. Our developed FSM testing by code coverage focuses on not only software system behavior but also data. We found higher code coverage rate, which indicates quality of system, by this method than existing black box testing method.

A digital power amplifier is combined with an analog power amplifier via a new ripple feedback filter for high power audio amplifier. Both high fidelity and high efficiency are achieved owing to the proposed filter in combination with a dynamic control of switching frequency. A prototype having a rated power of 2 kW is built for live concert use and tested successfully.