We formalize a model of "demonstration of program result-correctness," and investigate how to prove this fact against possible adversaries, which naturally extends Blum's theory of program checking by adding zero-knowledge requirements. The zero-knowledge requirements are universal for yes and no instances alike.

The field supported by multilayered periodic waveguides is well characterized by only one or two discrete leaky waves, rather than by a more complicated field representation that includes continuous spectra. The rigorous leaky-modes coupled in multilayered geometry can be then treated by relatively simpler and analytic model that describes the operation of practical optoelectronic devices in terms of leakage effects. To complement our modeling, we discuss and emphasize novel mathematical formulations based on the field orthogonality conditions of TE and TM modes coupled in multilayered periodic structures. In addition, to show the validity of our approach we numerically evaluate new physical meanings to illustrate quantitatively and rigorously the coupling efficiency of grating-assisted directional couplers (GADCs). The results reveal that the systematic and effective technique yields phenomenologically useful interpretations.

We have quantitatively and systematically investigated the effect of parasitic inductance on rapid single flux quantum (RSFQ) circuits by numerical simulation. While a parasitic inductance in parallel to a junction has virtually no effect on the circuit performance, a parasitic inductance in series with a junction significantly reduces the operating margins and speeds of circuits that have been optimized with the assumption that no parasitic inductance exists. To improve the reduced margins and speeds we have re-optimized the circuits for operation with parasitic inductance. While the speeds are sufficiently improved by the re-optimization procedure, the margins do not reach those without the parasitics. This suggests that the parasitic inductance shrinks the operating regions of the circuits and improvement of the margins by changing only the values of the parameters is limited. For further improvement of the margins it is important to employ processes and layouts that minimize the series parasitic inductance.

Within the next few decades, high-end telecommunication systems on the larger nationwide network will require a switching capacity of over 5 Tbps. Advanced optical transmission technologies, such as wavelength division multiplexing (WDM) will support optical-fiber data transmission at such speeds. However, semiconductors may not be capable of high-throughput data switching because of the limitations by power consumption and operating speed, and pin count. Superconducting single flux quantum (SFQ) technology is a promising approach for overcoming these problems. This paper proposed an optical-electrical-SFQ hybrid switching system and a novel switch architecture. This architecture uses time-shifted internal speedup, shuffle and grouping exchange and a Batcher-Banyan switch. Our proposed switch consists of an interface circuit with small buffers, a Batcher sorter, a time-shift-speedup buffer (TSSB), a Banyan switch, and a slowdown buffer. Simulations showed good scalability up to 100 Tbps, which no router could ever offer such features.

A single-chip MPEG-2 video, audio, and system encoder LSI has been developed. It performs concurrent real-time processing of MPEG-2 422P@ML video encoding, 2-channel Dolby Digital or MPEG-1 audio encoding, and system encoding that generates a multiplexed transport stream (TS) or a program stream (PS). Advanced hybrid architecture, which combines a high performance VLIW media-processor D30V and hardwired video processing circuits, has been adopted to satisfy the demands of both high flexibility and enormous computational capability. A unified control scheme has been newly proposed that hierarchically manages adaptive task priority control over asynchronous video, audio, and system encoding processes in order to achieve real-time concurrent processing using a single D30V. Dual dedicated motion estimation cores consisting of a coarse ME core (CME) for wide range searches and a fine ME core (FME) for precise searches have been integrated to produce high picture quality while using a small amount of hardware. Adopting these features, a single-chip encoder has been fabricated using 0.25-micron 4-layer metal CMOS technology, and integrated into a 14.2 mm 14.2 mm die with 11 million transistors.

The first important step in pre-processing data for 3D virtual colonoscopy requires careful segmentation of a complicated shaped colon. We describe an automatic colon segmentation method with a new patient-friendly bowel preparation scheme. This new bowel preparation makes the segmentation more appropriate for digitally removing undesirable remains in the colon. With the aim of segmenting the colon accurately, we propose two techniques which can solve the partial-volume-effect (PVE) problem on the boundaries between low and high intensity regions. Based on the features of the adverse PVE voxels on the gas and fluid boundary inside the colon, our vertical filter eliminates these PVE voxels. By seriously considering the PVE on the colon boundary, our gradient-magnitude-based region growing algorithm improves the accuracy of the boundary. The result of the automatic colon segmentation method is illustrated with both extracted 2D images from the experimental volumetric abdominal CT datasets and a reconstructed 3D colon model.

This paper describes a random access memory (RAM, sometimes also called an array) test scheme that has the following attributes: (1) Can be used in both built-in mode and off chip/module mode. (2) Can be used to test and diagnose naked arrays. (3) Fault diagnosis is simple and is "free" for some faults during test. (4) Is never subject to aliasing. (5) Depending upon the test length, it can detect many kinds of failures, like stuck-cells, decoder faults, shorts, pattern-sensitive, etc. (6) If used as built-in feature, it does not slow down the normal operation of the array. (7) Does not require storage of correct responses. A single response bit always indicates whether a fault has been detected. Thus, the storage requirement for the implementation of the test scheme is zero. (8) If used as a built-in feature, the hardware overhead is very low.

There are more and more information services provided on the wireless networks. Due to long network delay of wireless links, transactions will be long-lived transactions. In such a situation, the occurrence of handoff is inevitable, and thus a wireless link held by a mobile unit crossing cell boundaries might be forced to terminate. It is undesirable that an active transaction is forced to terminate. A queueing scheme has been proposed to solve the problem of forced termination of transactions in our previous research. However, when 2PL protocol is employed, suspending an active transaction will elongate the lock holding time and thus degrade the system performance. In this paper, we propose two guard channel schemes (GCS), static and dynamic, to reduce the probability of forced termination of transactions. In dynamic GCS, the number of channels reserved in a base station is dynamically assigned according to the number of transaction calls which may handoff to this cell while the number of guard channels is fixed in static GCS. An analytic model based on Markov chain is derived to evaluate the system performance. The correctness of this model is verified by simulation. The experimental results show that a significant improvement is achieved by using the dynamic GCS.

New good convolutional codes with optimal free distance are tabulated for the number of memories M 22 and rate R=1/2, which were selected based on the criterion of minimizing the decoding error rate and bit error rate. Furthermore, for R=1/3, 1/4 and M 13, we give the new good codes and make clear the existance of the codes with minimum free distance which achieve to Heller's upper bound for M 16.

Many new multimedia applications involve multiple dynamically changing participants, have stringent source-to-end delay requirements, and consume large amounts of network resources. A conventional algorithm that allows "two coming paths," where nodes in a multicast tree transmit several identical data flows, is therefore not practical. We have developed an algorithm for delay-constrained dynamic routing. This algorithm uses a QoS label to prevent the occurrence of "two coming paths," and can construct an efficient multicast tree for any traffic volume. The proposed algorithm was superior to conventional routing algorithms in terms of cost when nodes were added to or removed from the multicast group during a steady-state simulation.

B-ISDN is expected to be applied in the near future to video delivery systems for the broadcast of news and television programs. The demand for such services is increasing, and in particular, on-demand services are becoming more desirable. On-demand services allow viewers to request their favorite programs at the time that is convenient, hence catering for the wide range of modern lifestyles. As for on-demand services, there already exist Video on Demand (VoD) systems such as the original VoD or Near VoD. However, such systems have not yet been widely implemented because of the inefficient cost of communication resources, and storage. The authors' research is aimed at producing an efficient VoD system based on a high speed network. We are focused in particular on the forms of data transmission, and in this paper, we propose a new VoD system called Burst VoD. Burst VoD aggressively utilizes the multicasting technique, and involves dividing the program resource data into block files and transmitting them to viewer terminals as burst traffic over a high speed network. Simulation results comparing Burst VoD with conventional VoD show that Burst VoD achieves lower request blocking rates, efficient utilization of networks with multicasting, and almost on-demand response time to requests.

Watermarking techniques proposed up to now have some measure of robustness against non-geometrical alteration, however, most of them are not so robust against geometrical alteration. As also for video watermarking, small translation, scaling, rotation, affine transformation can be effective attacks on the watermark. In this paper, we propose an image correction scheme for video watermarking extraction. This scheme embeds 'patchwork' into digital video data for detection of positions, and corrects the images attacked by geometrical alteration on the basis of the detected positions. We also show the simulation results of applying proposed scheme to the conventional watermarking technique.

This paper is concerned with analysis of nonlinear dynamics under geometric constraints that express pinching motions of a pair of multi-degrees of freedom fingers with soft tips. The dynamics of such a pair of soft fingers can be expressed by a set of complicated nonlinear differential equations with algebraic constraints, even if the motion is constrained in a plane. However, it is shown from the passivity analysis that dynamic stable grasping (pinching) can be realized by means of a feedforward input of desired internal force with coefficients composed of elements of Jacobian matrices plus a feedback of the difference between moments of rotation exerted at both sides of the object. It is shown in the case of a pair of 2 d.o.f. and 3 d.o.f. fingers (corresponding to a pair of thumb and index fingers) that a principle of linear superposition is applicable to design of additional feedback signals for controlling simultaneously the posture (rotational angle) and position of the mass center of the object, though the dynamics are nonlinear. A sufficient condition for applicability of the principle of superposition is discussed and given as a condition for unique stationary resolution of the overall motion to elementary motions (stable grasping, rotation control, x and y coordinates control). The principle implies that a skilled motion can be resolved into some of elementary motions which human can learn separately and independently.

This paper treats meta-heuristics for combinatorial optimization problems. The parallelization of meta-heuristics is then discussed in which we show that parallel processing has possibility of not only speeding up but also improving solution quality. Finally we extend the discussion of the combinatorial optimization into autonomous decentralized systems, say autonomous decentralized optimization. This notion becomes very important with the advancement of the network-connected system architecture.

Nowadays, when people colloquially use the word "wireless," they almost always mean a portable telephone. Over the last 10 years, there has been tremendous growth in the mobile communications markets not only in Japan but also worldwide. For these 10 years, the most popular service has been dominated by voice communication. However, modern mobile communications systems are shifting their focus from solely voice communication to electronic mailing and Internet access. From now, we will evolve into a wireless multimedia society, where a combination of mobile communications and the Internet will play an important role. Wireless technology is the core of mobile communications systems. This article, which focuses on wireless technology, looks at how mobile communications systems have evolved over the last 10 years and looks to the future of advanced wireless technologies that will be necessary to realize a true wireless multimedia society in the coming decade.

A trapdoor one-way function is an extended version of a zero-way permutation. A zero-way permutation was first introduced by Niemi-Renvall in Asiacrypt'94. In this paper we define the class of functions called no-way functions. This is an extended version of a zero-way permutation. Intuitively, a function f is no-way if, without trapdoor, both computing f and computing f-1 are hard. Li-Chida-Shizuya defined the notion of a no-way function, which is a provable-security version of a zero-way permutation. They also gave an example of a no-way function such that computing f and f-1 is proven to be as hard as breaking the Diffie-Hellman key exchange scheme. We redefine the notion of a trapdoor no-way function more preciously, classify no-way functions by the property of the trapdoor: common, separated and semi-separated trapdoor no-way, give a method for constructing trapdoor no-way functions from trapdoor one-way functions, and also give an example of trapdoor no-way functions.

An aspect of the diverse developments of digital signal processing (DSP) over the last decade are summarized. The current progress of some core fields from the widespread fields are treated in this paper. The selected fields are filter design, wavelet theory and filter bank, adaptive signal processing, nonlinear filters, multidimensional signal processing, intelligent signal processing, and digital signal processor. Through the overview of recent research activities, the interdisciplinary character of the DSP should be proved. Some challenging research direction is described in the last section.

The goal of this paper is to describe a practical and efficient algorithm for computing in the Jacobian of a large class of algebraic curves over a finite field. For elliptic and hyperelliptic curves, there exists an algorithm for performing Jacobian group arithmetic in O(g2) operations in the base field, where g is the genus of a curve. The main problem in this paper is whether there exists a method to perform the arithmetic in more general curves. Galbraith, Paulus, and Smart proposed an algorithm to complete the arithmetic in O(g2) operations in the base field for the so-called superelliptic curves. We generalize the algorithm to the class of Cab curves, which includes superelliptic curves as a special case. Furthermore, in the case of Cab curves, we show that the proposed algorithm is not just general but more efficient than the previous algorithm as a parameter a in Cab curves grows large.

The concept of wireless ad hoc networking has unique features in which neither base stations nor wired backbone networks are required and a mobile node can communicate with a partner beyond the transmission range by multihopping. In this paper, innovations and issues in ad hoc network technologies are reviewed. The concept of a general-purpose ad hoc network is identified as a step toward next-generation ad hoc network development. The concept of an open community network is then presented as a vision for general-purpose ad hoc networks. An open community network is a novel information infrastructure for local communities based on wireless multihopping technologies, which may support an advanced information-oriented society in the twenty-first century. As a case study, an experimental system using PHS (Personal Handy Phone System) is described and some research issues for developing an open community network are identified.

We introduce efficient algorithms for scalar multiplication on elliptic curves defined over FP. The algorithms compute 2k P directly from P, where P is a random point on an elliptic curve, without computing the intermediate points, which is faster than k repeated doublings. Moreover, we apply the algorithms to scalar multiplication on elliptic curves, and analyze their computational complexity. As a result of their implementation with respect to affine (resp. weighted projective) coordinates, we achieved an increased performance factor of 1.45 (45%) (resp. 1.15 (15%)) in the scalar multiplication of the elliptic curve of size 160-bit.