Energy consumption is one of the most critical constraints in the current VLSI system designs. In addition, fault tolerance of VLSI systems will be also one of the most important requirements in the future shrunk VLSIs. This paper proposes practical low power and fault tolerant bus encoding methods in on-chip data transfer. The proposed encoding methods use the combination of simple low power code and fault tolerant code. Experimental results show that the proposed methods can reduce signal transitions by 23% on the bus with fault tolerance. In addition, circuit implementation results with bus signal swing optimization show the effectiveness of the proposed encoding methods. We show also the selection methodology of the optimum encoding method under the given requirements.

In this paper, we propose a new software reliability growth model which is the mixture of two exponential reliability growth models, one of which has the reliability growth and the other one does not have the reliability growth after the software is released upon completion of testing phase. The mixture of two such models is characterized by a weighted factor p, which is the proportion of reliability growth part within the model. Firstly, this paper discusses an optimal software release problem with regard to the expected total software cost incurred during the warranty period under the proposed software reliability growth model, which generalizes Kimura, Toyota and Yamada's (1999) model with consideration of the weighted factor. The second main purpose of this paper is to apply the Bayesian approach to the optimal software release policy by assuming the prior distributions for the unknown parameters contained in the proposed software reliability growth model. Some numerical examples are presented for the purpose of comparing the optimal software release policies depending on the choice of parameters by the non-Bayesian and Bayesian methods.

This paper quantitatively analyzes thermal gradient of SoC and proposes a thermal flattening procedure. First, the impact of dominant parameters, such as area occupancy of memory/logic block, power density, and floorplan on thermal gradient are studied quantitatively. Temperature difference is also evaluated from timing and reliability standpoints. Important results obtained here are 1) the maximum temperature difference increases with higher memory area occupancy and 2) the difference is very floorplan sensitive. Then, we propose a procedure to amend thermal gradient. A slight floorplan modification using the proposed procedure improves on-chip thermal gradient significantly.

There is "Processing speed improvement of the automatic fare collection gate (AFC gate)" as one of the important problems to correspond to the passengers getting on and off in high density transportation at the peak. On the other hand, reliability is indispensable to handle the ticket that is the note. Therefore, the ticket system that has both high-speed processing and high reliability is necessary and indispensable. For the passenger's convenience improvement and maintenance cost reduction, wireless IC card ticket system is hoped. However, the high-speed processing and the high reliability are ambivalent at this system because of wireless communications between an IC card and an AFC gate; the faster the AFC gate processes the ticket, the poorer the reliability gets. In this thesis, it proposes the autonomous decentralized processing technology to meet high-speed processing in wireless IC ticket system and the requirement of high reliability. "IC card" "AFC" and "Central server" are assumed to be an autonomous system. It proposes "Decentralized algorithm of the fare calculation by IC card and the AFC" to achieve high-speed processing. Moreover, "Autonomous, decentralized consistency technology" in each subsystem is shown for high-reliability. In addition, to make these the effective one, "Wireless communication area enhancing technology (touch & going method)" and "Command system for the data high speed processing" are shown. These technologies are introduced into the Suica system of East Japan Railway and the effectiveness has been proven.

The reliability-based heuristic search methods for maximum likelihood decoding (MLD) generate test error patterns (or, equivalently, candidate codewords) according to their heuristic values. Test error patterns are stored in lists and its space complexity is crucially large for MLD of long block codes. Based on the decoding algorithms both of Battail and Fang and of its generalized version suggested by Valembois and Fossorier, we propose a new method for reducing the space complexity of the heuristic search methods for MLD including the well-known decoding algorithm of Han et al. If the heuristic function satisfies a certain condition, the proposed method guarantees to reduce the space complexity of both the Battail-Fang and Han et al. decoding algorithms. Simulation results show the high efficiency of the proposed method.

How to safely or reliably flood a packet via broadcast scheme to all nodes in computer networks is an important issue. However, it is a big challenge and critical problem to broadcast data packets over mobile ad hoc networks reliably due to the unsettled wireless links, high mobility, and the lack of the acknowledgment (ACK) scheme. Many solutions deal with this problem by adopting multiple unicast transmissions to achieve reliable broadcast transmission in network layer. Unfortunately, it will cause severe duplicate transmissions and thus rapidly consume the limited network bandwidth. One simplest way to solve this drawback is to broadcast data packets in data link layer. But a serious problem will be arisen that replied ACK frames will collide at the sending node if we enforce each mobile node to reply an ACK after receiving the broadcast data frame. Therefore, in order to overcome the thorny problem, we proposed a broadcast engagement ACK mechanism (BEAM), which is completely compatible with the IEEE 802.11 protocol, for reliable broadcast transmission in the data link layer. We also show that the overhead of raising the reliability of broadcast transmission in network layer would be significantly reduced in data link layer. Simulation results show that the proposed BEAM can reach approximate 100% reliability even in heavy traffic load. We also indicate that the BEAM could be combined with other network layer broadcast schemes to approach higher flooding ratio as well as reduce bandwidth consumption effectively.

Under dynamic and heterogenous environment, the need for adaptability and rapid response time to information service systems has become increasingly important. To cope with the continuously changing conditions of service provision and utilization, Faded Information Field (FIF) has been proposed, which is an agent-based distributed information service system architecture. In the case of a mono-service request, the system is designed to improve users' access time and preserve load balancing through the information structure. However, with interdependent requests of multi-service increasing, adaptability, reliability and timeliness have to be assured by the system. In this paper, the relationship between the timeliness and the reliability of correlated services allocation and access is clarified. Based on these factors, the autonomous network-based heterogeneous information services integration technology to provide one-stop service for users' multi-service requests is proposed. We proved the effectiveness of the proposed technology through the simulation and the results show that the integrated service can reduce the total users access time compared with the conventional systems.

A new simple recovery scheme for transient bit errors in the RAM of a ROM-based embedded system is presented, which exploits the information stored in the ROM. And a new scrubbing technique suitable to the proposed recovery scheme is also presented. With the proposed recovery scheme and scrubbing technique, the reliability of the RAM against transient bit errors can be improved remarkably with no additional extra memory and scrubbing overhead.

Modern telecom and signal relays have been optimized to carry and switch low signals and to withstand high dielectric strength. Recent designs have extremely small physical dimensions and are comparatively cheap. Small size and low cost also make this type of relay very attractive for industrial and automotive applications. For industrial and automotive applications performance characteristics other than low and stable contact resistance values are of importance. While, for industrial applications, safety aspects and inductive load switching characteristics are of major importance, in automotive applications, high switching currents, inductive and lamp loads and high ambient temperatures are essential. Tests were carried out in order to determine the limitations of small size relays. The results obtained clearly show the unexpectedly high load range which signal relays are able to cover. Despite their small size, these relays can handle switching loads up to several hundred volts and currents up to 5 A. On top of the high switching current there is high excess current capability, and relays can work at extreme ambient temperatures between -55 and more than +105 degrees C.

We have developed an experimental approach that allows us to estimate the performance of a large-scale enterprise network to update routing information. This approach was applied to the integration of the UFJ Bank network system on January 15, 2002. The main characteristic of this approach is the application of a formula that represents the delays in updating routing information that accompany reductions in CPU resources. This procedure consists of two steps: one is to estimate the reduction in the availability of CPU resources caused by forwarding of data packets at a router, and the other is to estimate the levels of CPU resources required for replying to a query about a new route and subsequently updating the routing information. These steps were applied to estimate the performance of the network in terms of routing information convergence. The results of our experiments on the network showed that updating the routing information was possible as long as the average level of CPU utilization during any five-minute period at the routers was less than 40%. We were able to apply this guideline and thus confirm the stability of the UFJ Bank network.

We investigate the error exponent in the lossy source coding with a fidelity criterion. Marton (1974) established a formula of the reliability function for the stationary memoryless source with finite alphabet. In this paper, we consider a stationary memoryless source assuming that the alphabet space is a metric space and not necessarily finite nor discrete. Our aim is to prove that Marton's formula for the reliability function remains true even if the alphabet is general.

Photonic crystal fiber (PCF) is a promising candidate for future transmission media due to its unobtainable features in a conventional single-mode fiber. We discuss some important problems to realize a PCF for transmission purpose. We also present recent progress on the PCF as a transmission media.

Hypersequential programming is a new method of concurrent-program development in which the original concurrent program is first serialized, then tested and debugged as a set of sequential programs (scenarios), and finally restored into the target concurrent program by parallelization. Both high productivity and reliability are achieved by hypersequential programming because testing and debugging are done for the serialized versions and the correctness of the serialized programs is preserved during the subsequent parallelization. This paper proposes scenario-based hypersequential programming for reactive multitasking systems that have not only concurrency and nondeterminacy, but also interruption and priority. Petri nets with priority are used to model reactive systems featuring interruption and priority-based scheduling. How reactive systems are made highly reliable by this approach is explained and the effectiveness of the approach is demonstrated through the example of a telephone terminal control program.

In this paper, we present a model for evaluating the effectiveness of (2, 1, m) convolutional-code-based packet-level FEC, under the condition of a limited buffer size in which the number of available packets is restricted for recovery. We analytically derive the post-reconstruction receiving rate, i.e., the probability that a lost packet is received or recovered before the buffer limit is reached. We show numerical examples of the analytical results and demonstrate that the buffer size at the same level as m gives sufficient recovery performance.

We investigated the use of AlOx:N/SiNy stacked gate dielectric as an alternate gate dielectric, which were prepared by alternately repeating sub-nanometer deposition of Al2O3 from an alkylamine-stabilized AlH3 + N2O gas mixture and rapid thermal nitridation in NH3. The negative fix charges, being characteristics of almina, were as many as 3.91012 cm-2 in the effective net charge density. The effective dielectric constant and the breakdown field were 8.9 and 8 MV/cm, respectively, being almost the same as pure Al2O3. And we have demonstrated that the leakage current through the AlOx:N/SiNy stacked gate dielectric with a capacitance equivalent thickness (CET) of 1.9 nm is about two orders of magnitude less than that of thermally-grown SiO2. Also, we have confirmed the dielectric degradation similar to the stress-induced leakage current (SILC) mode and subsequent soft breakdown (SBD) reported in ultrathin SiO2 under constant current stress and a good dielectric reliability comparable to thermally-grown ultrahin SiO2. From the analysis of n+poly-Si gate metal-insulator-semiconductor field effect transistor (MISFET) performance, remote coulomb scattering due to changes in the gate dielectric plays an important role on the mobility degradation of MISFET with AlON/SiON gate stack.

It is an important problem to estimate component reliabilities. For a series system due to cost and time constraints associated with failure analysis, all components cannot be investigated and the cause of failure is narrowed to a subset of components in some cases. When such a case occurs, we say that the cause of failure is masked. It is also necessary in some cases to take account of the influence of an environmental stress on all components. In this paper, we consider 2 and 3-component series systems when the component lifelengths are exponentially distributed and an environmental stress follows either a gamma or an inverse Gaussian distribution. We show that the lifelength of the system and the cause of failure are independent of each other. By comparison between the hazard functions in both models, we see that quite short and long lifelengths are more likely to occur in a gamma model than in an inverse Gaussian one. Assuming that the masking probabilities do not depend on which component actually fails, we show that the likelihood function can be factorized into three parts by a reparametrization. For some special cases, some estimators are given in closed-form. We use the computer failure data to see that our model is useful to analyze the real masked data. As compared with the Kaplan-Meier estimator, our models fit this computer data better than no environmental stress model. Further, we determine a suitable model using AIC. We see that the gamma model is fitted to the data better than the inverse Gaussian one. From a limited simulation study for a 3-component series system, we see that the relative errors of some estimators are inversely proportional to the square root of the expected number of systems whose cause of failure is identified.

The reliability of a 266 nm cw (continuous-wave) solid-state laser under the influence of purge gas was considered. Scatterers on a mirror during long-term operation were ammonium sulfate (NH4SO4). The synthesis of ammonium sulfate was related to the amount of water in the purge gas. UV power decreased by scatterers when the purge was not conducted.

In this letter, we propose to construct reliable overlay data delivery tree based on group member's packet loss rate while preserving end-to-end delay below predetermined threshold. Through practical simulation, performance is evaluated and compared.

Reliability-based maximum likelihood decoding (MLD) algorithms of linear block codes have been widely studied. These algorithms efficiently search the most likely codeword using the generator matrix whose most reliable and linearly independent k (dimension of the code) columns form the identity matrix. In this paper, conditions for omitting unnecessary metrics computation of candidate codewords are derived in reliability-based MLD algorithms. The proposed conditions utilize an order relation of binary vectors. A simple method for testing if the proposed conditions are satisfied is devised. The method for testing proposed conditions requires no real number operations and, consequently, the MLD algorithm employing this method reduces the number of real number operations, compared to known reliability-based MLD algorithms.

We propose a new end-to-end transport protocol called Multi-path Transmission Control Protocol (M/TCP) and its two robust acknowledgement (ACK) schemes. Our protocol is designed as an alternative TCP option to improve reliability and performance of the Internet. The M/TCP sender simultaneously transmits data via multiple controlled paths to the receiver. Our protocol requires no modification in IP layer. Two M/TCP endpoints establish multiple paths between them by subscribing to multiple ISPs. The two robust ACK schemes proposed in this paper aim at improving M/TCP performance over the Internet with high packet loss in ACK channels. Performances between our protocol and TCP Reno are compared in terms of throughput and fairness by using ns2 simulator. Simulation results indicate that M/TCP achieves higher throughput than TCP Reno in situation of random drop and burst traffic with small buffer size. When there is network congestion on reverse path, M/TCP with the proposed robust ACK schemes performs better than M/TCP with the conventional immediate ACK scheme.