Array redistribution is required very often in programs on distributed memory parallel computers. It is essential to use efficient algorithms for redistribution, otherwise the performance of programs may degrade considerably. In this paper, we focus on automatic generation of communication routines for multi-dimensional redistribution. The principal advantage of this work is to gain the ability to handle redistribution between arbitrary source and destination processor sets and between arbitrary source and destination distribution schemes. We have implemented these algorithms using Parallelware communication library. Some experimental results show the efficiency and flexibility of our techniques compared to the other redistribution works.

This paper describes a factorization-based algorithm that reconstructs 3D object structure as well as motion from a set of multiple uncalibrated perspective images. The factorization method introduced by Tomasi-Kanade is believed to be applicable under the assumption of linear approximations of imaging system. In this paper we describe that the method can be extended to the case of truly perspective images if projective depths are recovered. We established this fact by interpreting their purely mathematical theory in terms of the projective geometry of the imaging system and thereby, giving physical meanings to the parameters involved. We also provide a method to recover them using the fundamental matrices and epipoles estimated from pairs of images in the image set. Our method is applicable for general cases where the images are not taken by a single moving camera but by different cameras having individual camera parameters. The experimental results clearly demonstrates the feasibility of the proposed method.

This paper presents a performance comparison between the single-stream and the multi-stream approaches to lip synchronization of live media (voice and video). The former transmits a single transport stream of interleaved voice and video, while the latter treats the two media as separate transport streams. Each approach has an option not to exert the synchronization control at the destination, which leads to four basic schemes. On an interconnected ATM-wireless LAN, we implemented the four basic schemes with RTP/RTCP on top of UDP and two variants which exercise dynamic resolution control of JPEG video. Making the performance measurement of the six schemes, we compare them to identify and evaluate advantages and disadvantages of each approach. We then show that the performance difference between the two approaches is small and that the dynamic resolution control improves the synchronization quality.

In this paper, a new overload control strategy is proposed for a call control processor (CCP) in the base station controller (BSC) and processor utilization is measured. The proposed overload control strategy can regulate the call attempts by adopting measured processor utilization. A function, specifically a linear interpolation function based on Inverse Transform theory is used to convert controlled predictive average load rate in a call rejection rate. Then a call admission rate is obtained from the call rejection rate. Simulation shows that the proposed algorithm yields better performance than the conventional algorithm does under the heavy transient overload status in terms of call admission rate.

In pursuing its vision that digital signals will come to dominate not only voice communications but also various services on an integrated basis in future telecommunications, NTT has successfully completed a major part of telephone network preparations by digitizing all of its networks by the end of 1997. Accompanying digitization, it has also started providing various new services including the initiation of best-effort services through OCN. At the same time, the steady progress in Internet diffusion, the globalization of enterprise networks and inter-company electronic transactions are leading to the full scale usage of IP network communications. Because IP networks are still faced with pressing demand and unresolved issues, NTT believes it is also necessary to structure and provide computer-compatible networks suitable for IP communications by shifting from telephone-focused architecture in order to respond better to these growing needs. This paper overviews the digital network assets including ISDN that NTT has accumulated as a carrier as well as the IP networks such as the Internet that have spread throughout our societies. It also outlines new access services and network offerings based on optical and other technologies and the ATM networks that serve as the infrastructure for highly reliable and economical IP networks, and presents our thinking behind how such networks will be organically combined.

In this paper, the bit error rate (BER) performance of the Spread Spectrum communication with Constrained Spreading Code system is studied under the synchronous CDMA system. Particularly, BER considering the tracking error is derived by theoretical analysis. The synchronizing spreading sequence is employed to track the signals in the receiver. As the result, the BER performance is degraded by increasing the number of users. However, the BER performance can be improved by canceling the co-channel interference and by suppressing the cross-correlation value between the information spreading sequence and the synchronizing spreading sequence.

We propose and demonstrate a simple polarization-independent construction of a local node for optical WDM ring networks using a centralized multiwavelength light source (MWLS). The node is simply composed of a 4-port optical circulator, an add/drop multiplexing (ADM) filter, a reflective modulator, and a drop fiber Bragg grating (FBG). A Faraday rotator mirror (FRM) is used to enable an LiNbO3 intensity modulator to operate in the polarization-independent mode. We examine three ADM filters, an interference filter, a fiber Fabry-Perot (FP) filter, and a set of FBG's. An optical WDM system experiment is performed to demonstrate the feasibility of the proposed node construction.

This paper formulates problems of fitting two corresponding sets of points by translation, rotation and scaling, and proposes efficient algorithms for the fitting. The algorithms are based on the theory of lower envelopes, or Davenport-Schinzel sequences, and linearization techniques in computational geometry, and are related to dynamic furthest Voronoi diagrams.

A fuzzy Kohonen clustering network was proposed which integrates the Fuzzy c-means (FCM) model into the learning rate and updating strategies of the Kohonen network. This yields an optimization problem related to FCM, and the numerical results show improved convergence as well as reduced labeling error. However, the clusters may be either hyperspherical-shaped or hyperellipsoidal-shaped, we use a generalized objective function involving a collection of linear varieties. In this way the model is distributed and consists of a series of `local' linear-type models (based on the revealed clusters). We propose a method to generalize the fuzzy Kohonen clustering networks. Anderson's IRIS data and the artificial data set are used to illustrate this method; and results are compared with the standard Kohonen approach and the fuzzy Kohonen clustering networks.

In this paper, we give lower bounds for the generalize Hamming weights of linear codes constructed on affine algebraic varieties. By introducing a number g*, which is determined by a given affine variety, we show that when the order t of generalized Hamming weights is greater than g*, the proposed lower bound agrees with their true generalize Hamming weights. Moreover, if we use the notion of well-behaving, we can obtain a more precise bound. Finally, we compare the proposed bound and the conventional one for algebraic geometric code on the curve Cab.

Exception handling is not only useful for increasing program readability, but also provides an effective means to check and locate errors, so it increases productivity in large-scale program development. Some typical and frequent program errors, such as out-of-range indexing, null dereferencing, and narrowing violations, cause exceptions that are otherwise unlikely to be caught. Moreover, the absence of a catcher for exceptions thrown by API procedures also causes uncaught exceptions. This paper discusses how the exception handling mechanism should be supported by the compiler together with the operating system and debugging facilities. This mechanism is implemented in the compiler by inserting inline check code and accompanying propagation code. One drawback to this approach is the runtime overhead imposed by the inline check code, which should therefore be optimized. However, there has been little discussion of appropriate optimization techniques and efficiency in the literature. Therefore, a new solution is proposed that formulates the optimization problem as a common assertion elimination (CAE). Assertions consist of check code and useful branch conditions. The latter are effective to remove redundant check code. The redundancy can be checked and removed precisely with a forward iterative data flow analysis. Even in performance-sensitive applications such as telecommunications software, figures obtained by a CHILL optimizing compiler indicate that CAE optimizes the code well enough to be competitive with check suppressed code.

Many object-oriented database systems have used the notion of implicit authorization to avoid the overhead caused by explicitly storing all authorizations for each object. In implicit authorization, it is very important to detect efficiently conflicts between existing authorizations and new authorizations to be added. In this article we propose a conflict detection mechanism in the OODBMSs using implicit authorization with the notion of intention type authorization. When we grant an authorization on a node n in the database granularity hierarchy, the existing method is inefficient in determining the conflicts since it needs to examine all authorizations on the descendants of the node n. In contrast, our mechanism has the advantage of detecting the conflicts at the node n where an explicit authorization is to be granted without examining any authorizations below the node n. Thus, the proposed mechanism can detect a conflict with the average time complexity of O(d), which is smaller than O(md) of existing methods, where m is the number of children nodes at an arbitrary level and d is the difference of levels between the node with an existing explicit authorization and the higher node where an explicit authorization is to be granted. We also show that the additional storage overhead of storing all authorizations is negligible when compared with the total number of all explicit authorizations.

A method for reconstructing realistic 3D human faces from computer tomography images and color photographs is proposed in this paper. This can be linked easily with the underlying bone and soft tissue models. An iteration algorithm has been developed for automatically estimating the virtual camera parameters to match the projected 3D CT image with 2D color photographs using known point correspondence. An approach has been proposed to select landmarks using a mouse with minimum error. Six landmarks from each image have been selected for front face matching and five for each side face matching.

An efficient hybrid scheme has been developed for optimizing register allocation applicable to CISC and RISC processors, which is crucial for maximizing their execution speed. Graph-coloring at the function level is combined with a powerful local register assigner. This assigner uses accurate program flows and access patterns of variables, and optimizes a wider local range, called an extended basic-block (EBB), than other optimizing compilers. The EBB is a set of basic-blocks that constitute a tree-shaped control flow, which is suitable for the large nested branches that frequently appear in embedded system-control programs, such as those for telephone call processing. The coloring at the function level involves only the live-ranges of program variables that span EBBs. The interference graph is therefore very small even for large functions, so it can be constructed quickly. Instead of iterative live-range splitting or spilling, the unallocated live-ranges are optimized by the EBB-based register assigner, so neither load/store insertion nor code motion is needed. This facilitates generating reliable code and debug symbols. The information provided for the EBB-based assigner facilitates the priority-based heuristics, fine-grained interference checking, and deferred coloring, all of which increase the colorability. Using a thread-support package for CHILL as a sample program, performance measurement showed that local variables are successfully located in registers, and the reduction of static cycles is about 20-30%. Further improvements include using double registers and improving debuggability.

An innovative small planar packaging(SPP)system is described that can be combined with card-on-board(COB)packaging in high-speed asynchronous transfer mode switching systems with throughput of over 40-Gb/s. The SPP system provides high I/O pin count density and high packaging density, combining the advantages of both planar packaging used in computer systems and COB packaging used in telecommunication systems. Using a newly developed quasi-coaxial zero-insertion-force connector, point-to-point 311 Mb/s of 8-bit parallel signal transmission is achieved in an arbitrary location on the SPP systems shelf. Also about 5400 I/O connections in the region of the planar packaging system are made, thus the SPP system effectively eliminates the I/O pin count limitation. Furthermore, the heat flux management capability of the SPP system is five times higher than of conventional COB packaging because of its air flow control structure. An SPP system can easily enlarge the switch throughput and it will be useful for future high-speed, high-throughput ATM switching systems.

Resonant properties of resistively shunted tunnel junctions dominate the high-frequency performance of Josephson array oscillators. To improve the operating frequency, we have developed resistively shunted Nb/AlOx/Nb tunnel junctions with a small parasitic inductance. The inductance was minimized by reducing the inductive length between the tunnel junction and the contact hole to be about 1µm. By fitting the measured I-V characteristics of the shunted tunnel junction to the simulated characteristics, we estimated the inductance to be about 105 fH. The analysis of resonant properties showed that the shunted tunnel junctions with the small parasitic inductance have a high-frequency performance up to the Nb gap frequency. Josephson array oscillators using 11 such junctions were designed and fabricated to operate at 650 GHz and 1 THz. Shapiro steps induced by Josephson oscillation were clearly observed up to 1 THz. By fitting the step heights to the simulated results, we estimated the output power of the Josephson oscillator delivered to the load resistor to be about 10 µW at 625 GHz and 50 nW at 1 THz.

In the commonsense reasoning, priorities among rules are often required to be found out in order to derive the desired conclusion as a theorem of the reasoning. In this paper, first we present the bottom-up and top-down abduction procedures to compute skeptical explanations and secondly show that priorities of circumscription to infer a desired theorem can be abduced as a skeptical explanation in abduction. In our approach, the required priorities can be computed based on the procedure to compute skeptical explanations provided in this paper as well as Wakaki and Satoh's method of compiling circumscription into extended logic programs. The method, for example, enables us to automatically find the adequate priority w. r. t. the Yale Shooting Problem to express a human natural reasoning in the framework of circumscription.

We propose a novel soft-decision decoding algorithm for cyclic codes based on energy minimization principle. The well-known soft-decision decoding algorithms for block codes perform algebraic (hard-decision) decoding several times in order to generate candidate codewords using the reliability of received symbols. In contrast, the proposed method defines energy as the Euclidean distance between the received signal and a codeword and alters the values of information symbols so as to decrease the energy in order to seek the codeword of minimum energy, which is the most likely codeword. We let initial positions be the information parts of signals obtained by cyclically shifting a received signal and look for the point, which represents a codeword, of minimum energy by moving each point from several initial positions. This paper presents and investigates reducing complexity of the soft-decision decoding algorithm. We rank initial positions in order of reliability and reduce the number of initial positions in decoding. Computer simulation results show that this method reduces decoding complexity.

In this paper, an algorithm for Boolean factoring is presented. The algorithm is based on a technique of rectangle covering. A distinctive feature of the algorithm is that no minimization step is required to achieve Boolean factoring. The method for computing Boolean products rests on the concepts of super-product, extended kernel and extended co-kernel-cube matrix. Results of a comparison with the algorithms GOOD_FACTOR and QUICK_FACTOR implemented in SIS are presented. SIS is a program for logic synthesis developed at the University of Berkeley. All performed tests indicate that the proposed algorithm realizes a good tradeoff between factoring quality and computing time.

This paper proposes a media synchronization mechanism for live media streams. The mechanism can also handle stored media streams by changing parameter values. The authors have implemented the mechanism on a lip-synch experimental system. Live video and voice streams input at a source workstation are transferred, and then they are synchronized and output at a destination workstation. This paper also evaluates the system performance such as mean square error of synchronization, average output rate, and average delay.