This paper describes two attacks against blind decryption (decode) based on the commutative random-self reducibility and RSA systems utilizing the transformability of digital signatures proposed in [2]. The transformable digital signature was introduced in [2],[8] for defeating an oracle attack, where the decrypter could be abused as an oracle to release useful information for an attacker acting as a requester of blind decryption. It was believed in [2],[8] that the correctness of a query to an oracle was ensured by the transformable signature derived from an original signature issued by the decrypter in advance, and a malicious query to an oracle could be detected before the blind decryption by the decrypter or would lead to release no useful information to an attacker. The first attack can decrypt all encrypted data with one access to an oracle. The second one generates a valid signature for an arbitrary message selected by an attacker abusing the validation check procedure.

The problem of constructing the proper-path-decomposition of width at most 2 has an application to the efficient graph layout into ladders. In this paper, we give a linear time algorithm which, for a given graph with maximum vertex degree at most 3, determines whether the proper-pathwidth of the graph is at most 2, and if so, constructs a proper-path-decomposition of width at most 2.

BTS (Binary-tree Timing Simulator) is a waveform-based switch-level timing simulator for VLSI circuits and the primary goal is to obtain an accurate waveform during the transient period. To achieve high accuracy, the internal charge effect should be considered because the delay behavior of a CMOS gate is dramatically influenced by internal charges stored in the internal nodes. However, the delay estimation will become a difficult problem when the charge sharing effect is considered. Therefore, this paper presents a recursive algorithm based on Modified Threaded Binary (MTB) tree for efficiently performing the internal-charge-delay estimation in transistor groups using the switch-level delay model. The algorithm CSEE (Charge Sharing Effect Estimation) can determine the charge distribution among the internal nodes, and then increases the accuracy of the waveform approximate technique used in BTS.

In this letter, a design method of linear-phase paraunitary filter banks is proposed for an odd number of channels. In the proposed method, a non-linear unconstrained optimization process is assumed to be applied to a lattice structure which makes the starting guess of design parameters simple. In order to avoid insignificant local minimum solutions, a recursive initialization procedure is proposed. The significance of our proposed method is verified by some design examples.

Physics principles of a new type of microwave input amplifiers are described. Cyclotron wave electrostatic amplifier (CWESA) has a low noise level, broad band, switchable gain, super high self-protection against microwave overloads, rapid recovery and small DC consumption. CWESAs are widely used in Russian pulse Doppler radars and other systems.

We have developed a parallel image processing RAM (PIP-RAM) which integrates a 16-Mb DRAM and 128 processor elements (PEs) by means of 0. 38-µm CMOS 64-Mb DRAM process technology. It achieves 7. 68-GIPS processing performance and 3. 84-GB/s memory bandwidth with only 1-W power dissipation (@ 30-MHz), and the key to this performance is the DRAM design. This paper presents the key circuit techniques employed in the DRAM design: 1) a paged-segmentation accessing scheme that reduces sense amplifier power dissipation, and 2) a clocked low-voltage-swing differential-charge-transfer scheme that reduces data line power dissipation with the help of a multi-phase synchronization DRAM control scheme. These techniques have general importance for the design of LSIs in which DRAMs and logic are tightly integrated on single chips.

We introduce a concept of regularization into Genetic Algorithms (GAs). Conventional GAs include no explicit regularizing operations. However, the regularization is very effective in solving ill-posed problems. So, we propose a method of regularization to apply GAs to ill-posed problems. This regularization is a kind of consensus operation among neighboring individuals in GAs, and plays the role of `smoothing the solution. ' Our method is based on the evaluation of macroscopic fitness, which is a new fitness criterion. Conventional fitness of an individual in GAs is defined only from the phenotype of the individual, whereas the macroscopic fitness of an individual is evaluated from the phenotypes of the individual and its neighbors. We tested our regularizing operation by means of experiments with an elastic image mapping problem, and showed the effectiveness of the regularization.

Presently, mobile robots are navigated by means of a number of methods, using navigating systems such as the sonar-sensing system or the visual-sensing system. These systems each have their strengths and weaknesses. For example, although the visual system enables a rich input of data from the surrounding environment, allowing an accurate perception of the area, processing of the images invariably takes time. The sonar system, on the other hand, though quicker in response, is limited in terms of quality, accuracy and range of data. Therefore, any navigation methods that involves only any one system as the primary source for navigation, will result in the incompetency of the robot to navigate efficiently in a foreign, slightly-more-complicated-than-usual surrounding. Of course, this is not acceptable if robots are to work harmoniously with humans in a normal office/laboratory environment. Thus, to fully utilise the strengths of both the sonar and visual sensing systems, this paper proposes a fusion of navigating methods involving both the sonar and visual systems as primary sources to produce a fast, efficient and reliable obstacle-avoiding and navigating system. Furthermore, to further enhance a better perception of the surroundings and to improve the navigation capabilities of the mobile robot, active sensing modules are also included. The result is an active sensor fusion system for the collision avoiding behaviour of mobile robots. This behaviour can then be incorporated into other purposive behaviours (eg. Goal Seeking, Path Finding, etc. ). The validity of this system is also shown in real robot experiments.

In this paper, we propose a new lemma facility, called the strong contraction rule, for model elimination calculus, and we study some implementation issues of strong contraction in a PTTP-based theorem prover. Strong contraction has the ability to shorten possible proofs and prevent some irrelevant computation to a target goal. Strong contraction never broadens the search space, in principle, and thus, has a stable effect on the acceleration of top-down proof search. However, it is difficult to embed the strong contraction into a PTTP-based theorem prover, because strong contraction imposes a truncation operation of center chains in model elimination calculus. We show a self-truncation-style Prolog code, which makes it possible to retain the high performance of a PTTP-based prover with strong contraction. Finally, we evaluate the performance and effect of strong contraction by performing some experiments.

In recent years, the rapid advancements of wireless communication technology and computer down-sizing technology have enabled users to utilize computing resources anywhere in the computer network. New applications constructed on the mobile database system are becoming popular. However, the current database systems do not provide special facilities for specific update operations in a mobile computing environment. Moreover, due to the lack of a common data handling method and a mutual communication mechanism, varieties in implementations may cause applications to be incompatible with each other. In this paper, we take up the issue of data handling, in a mobile computing environment, and propose an active mobile database system (AMDS) to solve this issue. First, we review the difficulties of dynamic update of databases in a mobile computing environment, and provide a basic concept of AMDS as a solution for these difficulties. In order to construct an AMDS, we focus on asynchronous events such as the appearance and disappearance of a mobile computer in a wireless communication cell. Then we provide a facility to specify the behavior of each system in Event-Condition-Action(ECA) rules in the same way as normal active database systems. Moreover, we show the architecture and the design of our implementation of AMDS. And, finally AMDS can be easily implemented as a common database infrastructure and work well on heterogeneous systems through indoor experiments.

In this paper, we propose dynamic cepstral representations to effectively capture the temporal information of cepstral coefficients. The number of speech frames for the regression analysis to extract a dynamic cepstral coefficient is inversely proportional to the cepstral order since the cepstral coefficients of higher orders are more fluctuating than those of lower orders. By exploiting the relationship between the window length for extracting a dynamic cepstral coefficient and the statistical variance of the cepstral coefficient, we propose three kinds of windowing methods in this work: an utterance-specific variance-ratio windowing method, a statistical variance-ratio windowing method, and an inverse-lifter windowing method. Intra-speaker, inter-speaker, and speaker-independent recognition tests on 100 phonetically balanced words are carried out to evaluate the performance of the proposed order-dependent windowing methods.

Many image-processing techniques are based on texture features or gradation features of the image. However, Landsat images are complex; they also include physical features of reflection radiation and heat radiation from land cover. In this paper, we describe a method of constructing a super-resolution image of Band 6 of the Landsat TM sensor, oriented to analysis of an agricultural area, by combining information (texture features, gradation features, physical features) from other bands. In this method, a knowledge-based hierarchical classifier is first used to identify land cover in each pixel and then the least-squares approach is applied to estimate the mean temperature of each type of land cover. By reassigning the mean temperature to each pixel, a finer spatial resolution is obtained in Band 6. Computational results show the efficiency of this method.

This paper investigates the relations between the computational complexity and the restrictions for several problems that determine whether a given graph with edge costs and edge lengths has a spanning subgraph with such restrictions as the diameter, the connectivity, and the NA-distance and the NA-(edge)-connectivity proposed and investigated in [1]-[5]. The NA-distance and the NA-(edge)-connectivity are the measures for the distance and the connectivity between a vertex and a vertex subset (area). In this paper we prove that the minimum diameter spanning subgraph problem considering the restrictions of the diameter and the sum of edge costs is NP-complete even if the following restrictions are satisfied: all edge costs and all edge lengths are equal to one, and the upper bound of the diameter is restricted to four. Next, we prove that the minimum NA-distance spanning subgraph problem considering the restrictions of the NA-distances and the sum of edge costs is NP-complete even if the following conditions are satisfied: all edge costs and all edge lengths are equal to one, the upper bound of the NA-distance is restricted to four, each area is composed of a vertex, and the number of areas is restricted to two. Finally, we investigate the preserving NA-distance and NA-edge-connectivity spanning subgraph problem considering the preservations of the NA-distances and the NA-edge-connectivity and the restrictions of the sum of edge costs, and prove that a sparse spanning subgraph can be constructed in polynomial time if all edge costs are equal to one.

Let T1, , Tn be n spanning trees rooted at node r of graph G. If for any node v, n paths from r to v, each path in each spanning tree of T1, , Tn, are internally disjoint, then T1, , Tn are said to be independent spanning trees rooted at r. A graph G is called an n-channel graph if G has n independent spanning trees rooted at each node of G. We generalize the definition of n-channel graphs. If for any node v of G, among the n paths from r to v, each path in each spanning tree of T1, , Tn, there are k internally disjoint paths, then T1, , Tn are said to be (k,n)-independent spanning trees rooted at r of G. A graph G is called a (k,n)-channel graph if G has (k,n)-independent spanning trees rooted at each node of G. We study two fault-tolerant communication tasks in (k,n)-channel graphs. The first task is reliable broadcasting. We analyze the relation between the reliability and the efficiency of broadcasting in (k,n)-channel graphs. The second task is secure message distribution such that one node called the distributor attempts to send different messages safely to different nodes. We should keep each message secret from the nodes called adversaries. We give two message distribution schemes in (k,n)-channel graphs. The first scheme uses secret sharing, and it can tolerate up to t+k-n listening adversaries for any t < n if G is a (k,n)-channel graph. The second scheme uses unverifiable secret sharing, and it can tolerate up to t+k-n disrupting adversaries for any t < n/3 if G is a (k,n)-channel graph.

Huet and Levy showed that index reduction is a normalizing strategy for every orthogonal strongly sequential term rewriting system. Toyama extended this result to root balanced joinable strongly sequential systems. In this paper, we present a class including all root balanced joinable strongly sequential systems and show that index reduction is normalizing for this class. We also propose a class of left-linear (possibly overlapping) NV-sequential systems having a normalizing strategy.

The asymptotic behavior of the recurrence time with fidelity criterion is discussed. Let X= be a source and Y= a database. For a Δ>0 and an integer l>0 define (Y,X,Δ) as the minimum integer N satisfying dl(,) Δ subject to a fidelity criterion dl. In this paper the following two i. i. d. cases are considered: (A) Xi P and Yi Q, where P and Q are probability distributions on a finite alphabet, and (B) Xi N(0,1) and Yi N(0,1). In case (A) it is proved that (1/l)log2(Y,X,Δ) almost surely converges to a certain constant determined by P, Q and Δ as l. The Kac's lemma plays an important role in the proof on the convergence. In case (B) it is shown that there is a quantity related to (1/l)log2 (Y,X,Δ) that converges to the rate-distortion bound in almost sure sense.

In a secure partially blind signature scheme, the signer assures that the blind signatures issued by him contains the information he desires. The techniques make it possible to minimize the unlimited growth of the bank's database which storing all spent electronic cash in an anonymous electronic cash system. In this paper we propose an efficient partially blind signature scheme for electronic cash. In our scheme, only several modular additions and modular multiplications are required for a signature requester to obtain and verify a signature. It turns out that the proposed scheme is suitable for mobile clients and smart-card applications because no time-consuming computations are required, such as modular exponentiation and inverse computations. Comparing with the existing blind signature schemes proposed in the literatures, our method reduces the amount of computations for signature requesters by almost 98%.

This paper proposes a top-down co-verification approach in the design of embedded systems composed of both hardware and software, for multimedia applications. In order to realize the optimized embedded system in cost, performance, power consumption and flexibility, hardware/software co-design becomes to be essential. In this top-down co-design flow, a target design is verified at three different levels: (1) algorithmic, (2) implementation, and (3) experimental. We have developed a methodology of top-down co-verification, which consists of the system level simulation at the algorithmic level, two type of co-simulations at the implementation level and the co-emulation at the experimental level. We have realized an environment optimized for verification performance by employing verification models appropriate to each verification stage and an efficient top-down environment by introducing the component logical bus architecture as the interface between hardware and software. Through actual application to a image compression and expansion system, the possibility of efficient co-verification was demonstrated.

This paper addresses the optimum routing problem of multipoint connection in large-scale networks. A number of algorithms for routing of multipoint connection have been studied so far, most of them, however, assume the availability of complete network information. Herein, we study the problem under the condition that only partial information is available to routing nodes and that routing decision is carried out in a distributed cooperative manner. We consider the network being partitioned into clusters and propose a cluster-based routing approach for multipoint connection. Some basic principles for network clustering are discussed first. Next, the original multipoint routing problem is defined and is divided into two types of subproblems. The global optimum multicast tree then can be obtained asymptotically by solving the subproblems one after another iteratively. We propose an algorithm and evaluate it with computer simulations. By measuring the running time of the algorithm and the optimality of resultant multicast tree, we show analysis on the convergent property with varying network cluster sizes, multicast group sizes and network sizes. The presented approach has two main characteristics, 1) it can yield asymptotical optimum solutions for the routing of multipoint connection, and 2) the routing decisions can be made in the environment where only partial information is available to routing nodes.

We have proposed a non-invasive method for diagnosis of the early stage of atherosclerosis, namely, the detection of small vibrations on the aortic wall near the heart by using ultrasound diagnostic equipment. It is, however, necessary to confirm the effectiveness of such measurement of the pulse wave velocity for quantitative evaluation of the local characteristics of atherosclerosis. It is well known that Young's modulus of a tube wall, estimated from measured pulse wave velocity, depends on inner pressure because of the non-linear relationship between the inner pressure and the change of volume in the tube. The inner pressure, however, changes during the period of one heartbeat. In this experimental study, we found for the first time that Young's modulus of the tube wall, estimated from the measured pulse wave velocity, depends not only on the diastolic pressure but also on the pulse pressure and the pressure gradient of the systolic period.