This paper proposes a new cell station (CS) configuration for personal communication systems. The proposed CS employs a modified coherent demodulator with 4-branch maximal ratio combining diversity and a burst-by-burst automatic frequency control (AFC) to enhance the coverage. The proposed CS also employs an antenna-sharing diversity transmission to incorporate more than one transceiver block into a small unit with high power efficiency. With these techniques, the BER performance of the uplink control channel (CCH) is flattened regardless of carrier frequency errors within 12 kHz; the diversity gain of uplink traffic channel (TCH) is improved by 2 dB; the downlink transmission power is reduced by 1.9 dB.

This paper presents results of subjective assessment of the media synchronization quality in the virtual-time rendering (VTR) media synchronization algorithm. For the assessment, stored voice and video streams were transmitted as two separate transport streams from a source to a destination on various traffic conditions in an experimental system. At the destination, they were output after synchronization control. We subjectively assessed the quality of media synchronization in a systematic way. This paper examines the effects of the difference between methods of recovery from asynchrony on the media synchronization quality. The paper also clarifies the relationships between the subjective and objective performance measures. Furthermore, it examines the effect of the difference in scene between media streams and that of the modification of the target output time on the media synchronization quality.

we evaluate the effect of express lots on production dispatching rule scheduling and cost in VLSI manufacturing final test process. In the assignment of express lots, we make comparisons of two rules, First In First Out (FIFO) rule which is widely used and WEIGHT+RPM rule which considers the time required for jig and temperature exchanges, the remaining processing time of the machine in use and the lot waiting time in queue. When using FIFO rule, the test efficiency begins to deteriorate and the test cost per chip begins to increase, if the content of express lots exceeds 15%. Furthermore, for 30% of express lots' content, the number of total processed lots decreases by 19% and the test cost per chip increases by 22% in comparison to the cases including no express lots. For WEIGHT+RPM rule, however, the test efficiency does not deteriorate and the test cost per chip does not increase even if the content of express lots is increased up to 50%. When we use WEIGHT+RPM rule, Express Lots Tolerances (ELTs), defined as the maximum content of express lots which permits the deterioration of the system characteristics by 5%, are about three times as high as ones when using FIFO rule. It is also found that WEIGHT+RPM rule maintains higher ELTs against the changes in the numbers of planned chips and prepared jigs as compared with FIFO rule.

We analyze the security of iterated 2m-bit hash functions with rate 1 whose round functions use a block cipher with an m-bit input (output) and a 2m-bit key. We first show a preimage attack with O(2m) complexity on Yi and Lam's hash function of this type. This means that their claim is wrong and it is less secure than MDC-2. Next, it is shown that a very wide class of such functions is also less secure than MDC-2. More precisely, we prove that there exist a preimage attack and a 2nd preimage attack with O(2m) complexity and a collision attack with O(23m/4) complexity, respectively. Finally, we suggest a class of hash functions with a 2m-bit hashed value which seem to be as secure as MDC-2.

We apply some variants of evolutionary computations to the fully-connected neural network model of associative memory. Among others, when we regard it as a parameter optimization problem, we notice that the model has some favorable properties as a test function of evolutionary computations. So far, many functions have been proposed for comparative study. However, as Whitley and his colleagues suggested, many of the existing common test functions have some problems in comparing and evaluating evolutionary computations. In this paper, we focus on the possibilities of using the fully-connected neural network model as a test function of evolutionary computations.

Let f be a one-to-one encryption function. Given f(m) and a string K, can we efficiently determine whether m contains K as a substring or not? We investigate the computational complexity of this problem, and show that it is equivalent to not only computing f-1 but also counting the number of K contained as substrings in m. Thus it is not determined in polynomial-time if f is in fact one-way.

For advanced data-oriented applications in distributed environments, effective information is frequently obtained by integrating or merging various autonomous information sources. There are many problems: how to search information sources, how to resolve their heterogeneity, how to merge or integrate target sources, how to represent information sources with a common protocol, and how to process queries. We have proposed a new language, QUIK, as an extension of a deductive object-oriented database (DOOD) language, QUIXOTE, and extend typical mediator systems. In this paper, we discuss various features of QUIK: programming capabilities as integrating an exchange model and mediator specifications, merging subsumption relations for maintaining consistency, searching alternative information sources by hypothesis generation, and identifying objects.

Simple expressions for constriction resistance of multitude conducting spots were analytically formulated by Greenwood. These expressions, however, include some approximations. Nakamura presented that the constriction resistance of one circular spot computed using the BEM is closed to Maxwell's exact value. This relative error is only e=0. 00162 [%]. In this study, the constriction resistances of two, five and ten conducting spots are computed using the boundary element method (BEM), and compared with those obtained using Greenwood's expressions. As the conducting spots move close to each other, the numerical deviations between constriction resistances computed using Greenwood's expressions and the BEM increase. As a result, mutual resistance computed by the BEM is larger than that obtained from Greenwood's expressions. The numerical deviations between the total resistances computed by Greenwood's expressions and that by the BEM are small. Hence, Greenwood's expressions are valid for the total constriction resistance calculation and can be applied to problems where only the total resistance of two contact surfaces, such as a relay and a switch, is required. However, the numerical deviations between the partial resistances computed by Greenwood's expression and that by the BEM are very large. The partial resistance calculations of multitude conducting spots are beyond the applicable range of Greenwood's expression, since Greenwood's expression for constriction resistance of two conducting spots is obtained by assuming that the conducting spots are equal size. In particular, the deviation between resistances of conducting spots, which are close to each other, is very large. In the case of partial resistances which are significant in semiconductor devices, Greenwood's expressions cannot be used with high precision.

The security of the ElGamal-type signature scheme is based on the difficulty of solving a discrete logarithm problem. If a random value that is introduced in the signing procedure is small, then the time for generating signature can be reduced. This strategy is particularly advantageous when a signer uses a smart card. In this paper, we show that the secret key can be computed efficiently if the random value is less than O(q) where q is the order of the generator.

The applicability of composite materials containing laminar solid lubricants to sliding contacts was studied. Performances of several composite materials prepared by incorporating solid lubricants with the basic alloys of the Cu-Nb system and Cu-Sn system were investigated to test the suitability of the composite materials as sliding contacts. As a result, it was clarified that the composite materials based on Cu-Sn alloy were superior to those based on Cu-Nb alloy and those containing only WS2 and not MoS2 were more effective in reducing both the contact resistance and the coefficient of friction. Based on the relationship between the contact resistance and the coefficient of friction obtained in this experimental study, the author proposed a new model for electric contact of composite materials.

The advent of high-speed networks with quality of service guarantees, will enable the deployment of data-server distributed systems over wide-area networks. Most implementations of data-server systems have been over local area networks. Thus it is important, in this context, to study the performance of existing distributed data management protocols in the new networking environment, identify the performance bottlenecks and develop protocols that are capable of taking advantage of the high speed networking technology. In this paper, we examine and compare the scalability of the server-based two-phase locking protocol (s-2PL), and the group two-phase locking protocol (g-2PL). The s-2PL protocol is the most widely used concurrency control protocol, while the g-2PL protocol is an optimized version of the s-2PL protocol, tailored for high-speed wide-area network environments. The g-2PL protocol reduces the effect of the network latency by message grouping, client-end caching and data migration. Detailed simulation results indicate that g-2PL indeed scales better than s-2PL. For example, upto 28% improvement in response time is reported.

This paper introduces a material management system for newspapers that was developed for The Yomiuri Shimbun. Material transferred to the system is stored in a material database and sent to terminals located in the related sections. The material can be processed effectively just by checking information on the terminals. Special requirements for this system will be discussed first in the paper, then problem-solving will be explored.

Decision trees are used as a convenient means to explain given positive examples and negative examples, which is a form of data mining and knowledge discovery. Standard methods such as ID3 may provide non-monotonic decision trees in the sense that data with larger values in all attributes are sometimes classified into a class with a smaller output value. (In the case of binary data, this is equivalent to saying that the discriminant Boolean function that the decision tree represents is not positive. ) A motivation of this study comes from an observation that real world data are often positive, and in such cases it is natural to build decision trees which represent positive (i. e. , monotone) discriminant functions. For this, we propose how to modify the existing procedures such as ID3, so that the resulting decision tree represents a positive discriminant function. In this procedure, we add some new data to recover the positivity of data, which the original data had but was lost in the process of decomposing data sets by such methods as ID3. To compare the performance of our method with existing methods, we test (1) positive data, which are randomly generated from a hidden positive Boolean function after adding dummy attributes, and (2) breast cancer data as an example of the real-world data. The experimental results on (1) tell that, although the sizes of positive decision trees are relatively larger than those without positivity assumption, positive decision trees exhibit higher accuracy and tend to choose correct attributes, on which the hidden positive Boolean function is defined. For the breast cancer data set, we also observe a similar tendency; i. e. , positive decision trees are larger but give higher accuracy.

In this paper, we propose a method, called PORT-D, for optimizing CMOS logic circuits to reduce the average power dissipation. PORT-D is an extensional method of PORT. While PORT reduces the average power dissipation under the zero delay model, PORT-D reduces the average power dissipation by taking into account of the gate delay. In PORT-D, the average power dissipation is estimated by the revised BDD traversal method. The revised BDD traversal method calculates switching activity of gate output by constructing OBDD's without representing switching condition of a gate output. PORT-D modifies the circuit in order to reduce the average power dissipation, where transformations which reduce the average power dissipation are found by using permissible functions. Experimental results for benchmark circuits show PORT-D reduces the average power dissipation more than the number of transistors. Furthermore, we modify PORT-D to have high power reduction capability. In the revised method, named PORT-MIX, a mixture strategy of PORT and PORT-D is implemented. Experimental results show PORT-MIX has higher power reduction capability and higher area optimization capability than PORT-D.

This paper proposes a novel one-way hash function that can serve as a tool in achieving authenticity and data integrity. The one-way hash function can be viewed as a representative of a family of fast dedicated one-way hash functions whose construction is based on linear cellular automata over GF(a). The design and analysis of security of the function is accomplished by the use of very recently published results on cellular automata and their applications in cryptography. The analysis indicates that the one-way hash function is secure against all known attacks. A promising property of the proposed one-way hash function is that it is especially suitable for compact and fast implementation.

In this paper, we propose two methods of digital watermark for image signals based on the wavelet transform. We classify wavelet coefficients as insignificant or significant by using zerotree which is defined in the embedded zerotree wavelet (EZW) algorithm . In the first method, information data are embedded as watermark in the location of insignificant coefficients. In the second method, information data can be embedded by thresholding and modifying significant coefficients at the coarser scales in perceptually important spectral components of image signals. Information data are detected by using the position of zerotree's root and the threshold value after the wavelet decomposition of an image in which data hide. It is shown from the numerical experiments that the proposed methods can extract the watermark from images that have degraded through several common signal and geometric processing procedures.

This paper proposes the first provably secure multi-signature schemes under the random oracle model. The security of our schemes can be proven in the sense of concrete security in Ref. [13]. The proposed schemes are efficient if the random oracle is replaced by practical hash functions. The essential techniques in our proof of security are the optimal reduction from breaking the corresponding identification to breaking signatures (ID Reduction Technique), and the hierarchical heavy row lemmas used in the concrete reduction from solving the primitive problem to breaking the identification scheme.

Epsilon serializability (ESR) was proposed to relax serializability constraints by allowing transactions to execute with a limited amount of inconsistency (ε-spec). Divergence control algorithms, viewed as extensions of concurrency control algorithms, enable read-only transactions to complete if their inconsistencies do not exceed ε-spec. This paper studies the performance of two-phase locking divergence control (2PLDC) and optimistic divergence control (ODC) algorithms. We develop a central part of the ESR transaction processing system that runs with 2PLDC and ODC. We applied a comprehensive centralized database simulation model to measure the performance. Evaluations are conducted with multi-class workloads where on-line update transactions and long-duration queries progress under various ε-spec. Our results demonstrate that significant performance enhancements are achieved with a non-zero tolerable inconsistency. With sufficient ε-spec and limited system resources, both algorithms result in comparable performance. However, with low resource contention, ODC performs significantly better than 2PLDC. Furthermore, in the range of small ε-spec, the queries committed by ODC have more accurate results than those committed by 2PLDC.

Voice activity detection (VAD) is to determine whether a short time speech frame is voice or silence. VAD is useful in reducing the mean speech coding rate by suppressing transmission during silence periods, and is effective in transmitting speech and other data simultaneously. This letter describes a VAD system that uses a neural network. The neural network gets several parameters by analyzing slices of the speech wave form, and outputs only one scalar value related to voice activity. This output is compared to a threshold to determine whether the slice is voice or silence. The mean code transfer rate can be reduced to less than 50% by using the proposed VAD system.

The productivity of developing software for switching systems and the effects of using advanced software development methods were evaluated and analyzed. Productivity was found to be improved by using automatic code generation, simulator debugging, a hierarchical object-oriented software structure, and software-development-support tools. The evaluation showed that the total productivity was improved by about 20%, compared with a case where these efforts were not introduced. It also showed each effect of these methods and tools by evaluating their manpower saving ratios. These results are expected to benefit the development of various types of communication-switching and multimedia service systems. Also, our development-support tools and methods are expected to be the basis for attaining higher software development productivity.