In this paper, we present new algorithms to calculate the reverse distance transformation and to extract the skeleton based upon the Euclidean metric for an arbitrary binary picture. The presented algorithms are applicable to an arbitrary picture in all of n-dimensional spaces (n2) and a digitized picture sampled with the different sampling interval in each coordinate axis. The reconstruction algorithm presented in this paper is resolved to serial one-dimensional operations and efficiently executed by general purpose computer. The memory requirement is very small including only one picture array and single one-dimensional work space array for n-dimensional pictures. We introduce two different definitions of skeletons, both of them allow us to reconstruct the original binary picture exactly, and present algorithms to extract those skeltons from the result of the squared Euclidean distance transformation.

In this paper we estimate the number of permutations realizable in fault-tolerant multistage interconnection networks designed to tolerate faults on any switching element. The Parallel Omega network and the INDRA network are representative types of fault-tolerate multistage interconnection networks designed to tolerate a single fault. In order to evaluate the enhancement in the function of network by preparing the hardware redundancy for fault-tolerance, we estimate the number of permutations realizable in fault-tolerant networks. This result enables us to set up a standard to evaluate the hardware redundancy required to tolerate multifaults from the viewpoint of the enhancement of network function. This paper concludes that in the case where the number of inputs is up to 32 the increase ratio of the number of realizable permutations is no more than 1/0.73 even if the tolerance to multifaults is prepared instead of the tolerance to a single fault.

Many methods, based on the concept of key-lock-pair have been proposed for access control in computer protection systems. However, the proposed methods still either lack of dynamic ability or need quite a lot of computation in performing requests of deleting users/files, inserting users/files, or updating access rights of users to files. In this paper we propose a two-key-lock-pair access control method that is based on the unique factorization theorem and a time stamp mechanism. Our method is dynamic and needs a minimum amount of computation in the sense that it only updates at most one key/lock for each access request, which has not been achieved before.

The stability of a terminated two-port network is investigated, and the stability conditions with only one inequality are obtained. Furthermore, the stability conditions with two inequalities, which are in the same form as those for the passive terminations known at the present time, are also obtained.

Optical WDM (Wavelength Division Multiplexing) technology is a method of exploiting the huge bandwidth of optical fibers. Local lightwave networks which use fixed wavelength transmitters and receivers can be built in a multihop fashion. In multihop local lightwave networks, packets arrive at their destination by hopping a number of intermediate nodes. The channel sharing schemes for multihop lightwave networks have been proposed for efficient channel utilization, but those schemes result in the degradation of network capacity and the user throughput. In this paper, we propose an improved WDM channel sharing scheme using the logically bidirectional perfect shuffle interconnection pattern, achieving smaller number of average hops for transmission and better channel utilization efficiency. Better channel utilization efficiency is obtained without much deteriorating the network capacity and the user throughput. TDMA (Time Division Multiple Access) protocol can be used to control the sharing of channels, and time delay and lost packet probability analysis based on TDMA is performed.

The paper discusses properties of YBaCuO thick films produced by screen printing method and followed sintering of a paste made from pre-annealed powder on Yttrium Stabilized Zirconia (YSZ) and MgO substrates. The prepared films have been studied by X-ray diffraction, scanning electron microscopy (SEM) and resistance vs. temperature measurements.

Ultrathin GaAs, AlGaAs and GaAs/InAs wire crystals (whiskers) as thin as 20-50 nm are grown by organometallic vapor phase epitaxy (OMVPE) using Au as a growth catalyst. It is found that the whisker shape and width can be controlled by adjusting the thickness of the Au deposited on the substrate surface and the substrate temperature duing OMVPE. A new technique employing a scanning tunneling microscope (STM) for controlling the whisker growth position on the substrate surface is described. Photoluminescence spectra from the GaAs whiskers show a blue shift of the luminescene peak energy as the whisker width decreases. The amount of blue shift energy is rather small compared to that calculated by a simple square potential well model. The discrepancy is explained by the cylindrical potential well model including the surface depletion effect. Atomic composition within the portion of 1-20 nm along the AlGaAs and GaAs/InAs whiskers has been analyzed by energy dispersive X-ray analysis in combination with transmission electron microscopy. This shows the exsitence of Au at the tip of the whisker and the composition change occurs over a length of less than 5 nm at the GaAs/InAs heterojunction.

We studied the selective epitaxy of GaAs grown by a technique called pulsed-jet epitaxy. Pulsed-jet epitaxy is a kind of atomic layer epitaxy (ALE) based on low-pressure metalorganic vapor-phase epitaxy (MOVPE). We compared growth behavior and layers grown by ALE and MOVPE. During ALE we supplied trimethylgallium (TMGa) and arsine (AsH3) alternately; however, during MOVPE we supplied TMGa and AsH3 simultaneously. At a growth temperature of 500, we obtained a better growth selectivity using ALE than using MOVPE. The lateral thickness profile of the ALE-grown GaAs layer at the edge of SiO2 mask was uniform. In contrast, the MOVPE growth rate was enhanced near the mask edge. Using ALE, we selectively grew GaAs epilayers even at mask openings with submicron widths. Scanning electron microscopy revealed that the ALE selectively grown structures had an uniform thickness profile, though the facets surrounding the structures depended on the orientation of mask stripes. After MOVPE, however, the (001) surface of the deposited layer was not flat because of the additional lateral diffusion of the growth species from the gas phase and/or the mask surface and some crystal facets. The experimental results show that, using ALE, we can control the shape of selectively grown structures. Selective epitaxy by ALE is a promising technique for fabricating low-dimensional quantum effect devices.

The static and dynamic characteristics of the lateral IGBT on the SOI film when the collector voltage of the IGBT is applied to the substrate are invesigated for its application to the high side switch. The measurements on the blocking capability and the switching characteristics under an inductive load are carried out with varying the thickness of the SOI film. The 260 V IGBT can be fabricated on the 5 µm thick SOI film without the special device structure. It is confirmed that the switching speed depends strongly on the SOI film thickness, not on the substrate bias. The dynamic latch-up current during the turn-off transient increases with the decrease in the SOI film thickness. This is caused by the large transient substrate current. This paper exhibits that applying the collector voltage of the IGBT to the substrate makes it possible to improve the characteristics of the IGBT on the thin SOI film.

Development of a large-scale mobile communications network (IMN: Intelligent Mobile communications Network), as an infrastructure integrating multimedia functions, is indispensable for the support of future mobile communication services aiming toward "personalization," "intelligence," and "multimedia services." This paper discusses the aims of mobile communications and the outline of network technology aspects of PDC (Personal Digital Cellular) network which is currently in service. In addition, the future prospect of mobile communication technologies is discussed with special focuses on the support of universal mobility, network architecture including mobile communications platform, and multimedia technologies in the transport and access systems.

To provide personal, intelligent, and multimedia services through a mobile communications network, a Mobile Service Control Point (M-SCP) was developed, which performs both the location register and service control functions. The M-SCP was constructed on a common platform to allow quick introduction of new services. Software techniques to reduce the frequency of process-switching, assign the highest priority to real-time tasks, and operate a multiple-CPU structure provide faster real-time processing. This is confirmed by computer simulation and research in the field.

The techniques for imaging optically opaque region using an electromagnetic wave radar are being developed. One important application of these techniques is the detection of buried pipes and cables. The image quality of subsurface radar often becomes low because the electromagnetic waves are affected by the attenuation and inhomogeneity of soil. Hence, a method which improves the quality of the radar images has been required. The migration method is utilized in reflective seismic processing and is derived based on the solution of the wave equation represented in spatial frequency domain. It is classified into the F-K and the phase-shift (P-S) migration method. The former is derived on the assumption that propagation velocity of the wave is uniform in the soil while the latter is assumed that the propagation velocity is varying depending on the depth from the ground surface. The P-S method gives relatively good quality images but it requires very long computation time. In this paper, we propose the block migration method in which the F-K method is applied to the divided image blocks with local propagation velocity. In order to solve a problem concerning the connection between the contiguous blocks we present two approaches which are the processings using the overlapped regions and the Lapped Orthogonal Transform (LOT). Some experimental results point out that the block migration method has a good capability of improving the image quality and the processing time using LOT becomes one tenth in comparison with the P-S method.

In this paper, we proposes a novel fuzzy control for parameter scheduling of the Hopfield neural network. When a combinatorial optimization problem, such as the traveling salesman problem, is solved by Hopfield neural network, it is efficient to adaptively change the parameters of the energy function and sigmoid function. By changing the parameters on purpose, this network can avoid being trapped at a local minima. Since there exists complex relations among these parameters, it is difficult to analytically determine the ideal scheduling. First, we investigate a bad scheduling to change parameters by simple experiments and find several rules that may lead to a good scheduling. The rules extracted from the experimental results are then realized by fuzzy control. By using fuzzy control, we can judge bad scheduling from vague network stages, and then correct the relations among the parameters. Computer simulation results of the Traveling Salesman Problem (TSP) is considered as an example to demonstrate its validity.

Go-Back-N automatic repeat request (GBN ARQ) and Stop-and wait (SW) ARQ schemes are one of fundamental and widely used error control procedures for data communication and computer communication systems. The throughput and delay performances of these ARQ schemes have been analyzed for a random error channel, which could not applicable for a radio channel, for example. In this paper, considering the correlated, noisy channel, we derive the exact formula for the delay of a frame in GBN and SW ARQ schemes. First, the delay formula for the discrete time M[x]/G/1 queueing system with starter. Next, the virtual service time of a frame is found in terms of the decay factor of a two-state Markov chain. As a result, it is shown that the performance of the delay is improved with the larger decay factor.

A method is presented for computing the number of codewords of weight less than or equal to a given integer in a binary block code by using its trellis diagram. The time and space complexities are analyzed. It is also shown that this method is very efficient for the codes which have relatively simple trellis diagram, say some BCH codes. By using this method, the weight distribution of (128,36) extended BCH code is computed efficiently.

This paper describes highly parallel analog image coding and decoding by cellular neural networks (CNNs). The communication system in which the coder (C-) and decoder (D-) CNNs are embedded consists of a differential transmitter with an internal receiver model in the feedback loop. The C-CNN encodes the image through two cascaded techniques: structural compression and halftoning. The D-CNN decodes the received data through a reconstruction process, which includes a dynamic current distribution, so that the original input to the C-CNN can be recognized. The halftoning serves as a dynamic quantization to convert each pixel to a binary value depending on the neighboring values. We approach halftoning by the minimization of error energy between the original gray image and reconstructed halftone image, and the structural compression from the viewpoints of topological and regularization theories. All dynamics are described by CNN state equations. Both the proposed coding and decoding algorithms use only local image information in a space inveriant manner, therefore errors are distributed evenly and will not introduce the blocking effects found in DCT-based coding methods. In the future, the use of parallel inputs from on-chip photodetectors would allow direct dynamic quantization and compression of image sequences without the use of multiple bit analog-to-digital converters. To validate our theory, a simulation has been performed by using the relaxation method on an 150 frame image sequence. Each input image was 256256 pixels whth 8 bits per pixel. The simulated fixed compression rate, not including the Huffman coding, was about 1/16 with a PSNR of 31[dB]35[dB].

This paper describes a pipelining universal system of discrete time cellular neural networks (DTCNNs). The new relaxation-based algorithm which is called a Pipelining Gauss Seidel (PGS) method is used to solve the CNN state equations in pipelining. In the systolic system of N processor elements {PEi}, each PEi performs the convolusional computation (CC) of all cells and the preceding PEi-1 performs the CC of all cells taking precedence over it by the precedence interval number p. The expected maximum number of PE's for the speeding up is given by n/p where n means the number of cells. For its application, the encoding and decoding process of moving images is simulated.

A new recursive method for obtaining the mean waiting time in a polling system with general service order and gated service discipline is proposed. The analytical approach used to obtain the mean waiting time is via an imbedded Markov chain and a new recursive method is used to obtain the moments of pseudocycle time which are parameters in the formula for the mean waiting time. This method is computationally tractable, so the analytical results can cover a wide range of applications. Simulations are also conducted to verify the validity of the analysis.

The throughput performance of a slotted, non-persistent Idle-Signal Casting Multiple Access (ICMA) protocol under the effects of various combinations of Rayleigh fading, lognormal shadowing, and spatial distribution of mobile users is studied. The opposing effects of propagation impairments on the performance of the protocol through simultaneously increasing the probability of receiver capture and attenuation of the received signal power level are demonstrated.

This paper proposes a dynamically randomized version of DES (called RDES) in which a input-dependent swapping Sk(X) is added onto the right half of the input in each round of DES. This new scheme decreases the probability of success in differential cryptanalysis because it decreases the characteristic probability. Each "best" two-round characteristic probability is analyzed for typical schemes of the RDES: (i) RDES-1 with a simple one-level swapping, (ii) RDES-1' with an optimal one-level swapping, (iii) RDES-2 with a simple two-level swapping, and (iv) RDES-2' with an optimal two-level swapping. The main results are as follows. (a) The differential attacks on the 16-round RDES-1' and the 16-round RDES-2 require more computational time than the exhaustive search. (b) A differential attack is substantially inapplicable to the 16-round RDES-2' because more than 263 chosen plaintext pairs are required. (c) The encryption/decryption speed of the n-round RDES is almost the same as that of the n-round DES.