This paper presents a network surveillance technique for detecting malicious activities. Based on the hypothesis that unusual conducts like system exploitation will trigger an abnormal network pattern, we try to detect this anomalous network traffic pattern as a sign of malicious, or at least suspicious activities. Capturing and analyzing of a network traffic pattern is implemented with a concept of port profiling, where measures representing various characteristics of connections are monitored and recorded for each port. Though the generation of the port profiles requires the minimum calculation and memory, they exhibit high stability and robustness. Each port profile retains the patterns of the corresponding connections precisely, even if the connections demonstrate multi-modal characteristics. By comparing the pattern exhibited by live traffic with the expected behavior recorded in the profile, intrusive activities like compromising backdoors or invoking trojan programs are successfully detected.

This letter introduces a new digital halftoning technique based on error diffusion along a random space-filling curve. The purpose of introducing randomness is to erase regular patterns which tend to arise in an image area of uniform intensity. A simple algorithm for generating a random space-filling curve is proposed based on a random spanning tree and maze traversal. Some experimental results are also given.

This report describes AlGaAs/GaAs HBT ICs for 20-Gb/s optical transmission, the preamplifier and optical modulator driver circuits, and those ICs for 10-Gb/s clock extraction circuits, the rectifier and phase shifter circuits. These ICs were fabricated using our developed hetero guard-ring fully self-aligned HBT (HG-FST) fabrication process. The Pt-Ti-Pt-Au multimetal system was also used as a base ohmic metal to reduce base contact resistance, and a high fmax of 105 GHz was obtained. Good results in the HBT IC microwave performances were achieved from the on-wafer measurements. The preamplifiers exhibited the broad bandwidth of 20. 9 GHz. The optical modulator driver performed a sufficiently large output-voltage swing of 4-VP-P at a 20-Gb/s data rate. The rectifier and the phase shifter circuits achieved good operations at 10-Gb/s. These results suggest that these HBT ICs can be applied to 20-Gb/s optical transmission and 10-Gb/s clock extraction systems.

SiGe HBTs with doping level inversion, that is, a higher dopant concentration in the base than in the emitter, are realized based on the double-polysilicon self-aligned transistor scheme by means of selective epitaxy performed in a production CVD reactor. The effects of the Ge profile in the base on the transistor performance are explored. The fabricated HBT with a 12-27% graded Ge profile demonstrates a maximum cutoff frequency of 88 GHz, a maximum oscillation frequency of 65 GHz, and an ECL gate delay time of 13.8 ps.

The goal of this paper is to present a critical survey of existing literature on an omnidirectional sensing. The area of vision application such as autonomous robot navigation, telepresence and virtual reality is expanding by use of a camera with a wide angle of view. In particular, a real-time omnidirectional camera with a single center of projection is suitable for analyzing and monitoring, because we can easily generate any desired image projected on any designated image plane, such as a pure perspective image or a panoramic image, from the omnidirectional input image. In this paper, I review designs and principles of existing omnidirectional cameras, which can acquire an omnidirectional (360 degrees) field of view, and their applications in fields of autonomous robot navigation, telepresence, remote surveillance and virtual reality.

Phase performance in a fiber optic temperature sensor using a mode-division multiplex is studied. The phase shift due to the temperature change of a multimode graded-index optical fiber is analyzed. The intensity fluctuation by the interference of two modes is estimated in computer simulation.

In this paper, the authors present general views of computer vision and image processing based on optimization. Relaxation and regularization in both broad and narrow senses are used in various fields and problems of computer vision and image processing, and they are currently being combined with general-purpose optimization algorithms. The principle and case examples of relaxation and regularization are discussed; the application of optimization to shape description that is a particularly important problem in the field is described; and the use of a genetic algorithm (GA) as a method of optimization is introduced.

In this article we present a survey of medical image processing with the stress on applications of image generation and pattern recognition / understanding to computer aided diagnosis (CAD) and surgery (CAS). First, topics and fields of research in medical image processing are summarized. Second the importance of the 3D image processing and the use of virtualized human body (VHB) is pointed out. Thirdly the visualization and the observation methods of the VHB are introduced. In the forth section the virtualized endoscope system is presented from the viewpoint of the observation of the VHB with the moving viewpoints. The fifth topic is the use of VHB with deformation such as the simulation of surgical operation, intra-operative aids and image overlay. In the seventh section several topics on image processing methodologies are introduced including model generation, registration, segmentation, rendering and the use of knowledge processing.

Acquisition of three-dimensional information of a real-world scene from two-dimensional images has been one of the most important issues in computer vision and image understanding in the last two decades. Noncontact range acquisition techniques can be essentially classified into two classes: Passive and active. This paper concentrates on passive depth extraction techniques which have the advantage that 3-D information can be obtained without affecting the scene. Passive range sensing techniques are often referred to as shape-from-x, where x is one of visual cues such as shading, texture, contour, focus, stereo, and motion. These techniques produce 2.5-D representations of visible surfaces. This survey discusses aspects of this research field and reviews some recent advances including video-rate range imaging sensors as well as emerging themes and applications.

This paper presents a high-speed CAC scheme, called PERB CAC (CAC based on Prior Estimation for Residual Bandwidth). This scheme estimates the residual bandwidth in advance by generating virtual requests for connection. When an actual new request occurs, PERB CAC can instantaneously judge if the required bandwidth is larger than the estimated residual bandwidth. PERB CAC provides very rapid response time both for statistical and deterministic bandwidth allocation services, while keeping statistical multiplexing gain for the former service. Numerical results indicate that PERB CAC provides reasonably accurate and conservative values of residual bandwidth. In addition, by using PERB CAC, both services are able to be accommodated into a single VP. VP capacity control is more relaxed than is true with conventional VP-separation management. This is another merit of PERB CAC. Therefore, PERB CAC can achieve high-speed connection set-up while utilizing network resources in a cost-effective manner.

This paper proposes a medium access control (MAC) protocol for single-hop WDM star-coupler networks, in which the number of stations is larger than the number of channels and the stations have arbitrary distances to the star coupler. The proposed protocol has one control channel for reserving the slots of data channels and several data channels which are used to transmit traffic. This paper also suggests a scheme that accomplishes load balancing among data channels for arbitrary traffic patterns between stations. Since this load balancing scheme diminishes an influence that traffic patterns have on the performance of the proposed MAC protocol, the proposed system is appropriate for systems which have asymmetric traffic intensity between stations. Throughput and mean message delay of the MAC protocol are analyzed using a discrete time Markov process and a D/G/1 queue with batch arrivals. The numerical results show that the performance is improved as the message length increases, the maximum round-trip propagation delay decreases, and the number of data channels increases.

This paper proposes an algorithm for analyzing the reachability property of Petri nets by the use of unfoldings. It is known that analyzing the reachability by using unfoldings requires exponential time and space to the size of unfolding. The algorithm is based on the branch and bound technique, and experimental results show efficiency of the algorithm.

In this paper, the bit error rate (BER) of 16 differential amplitude phase shift keying (16DAPSK) modems in future mobile communication system is derived analytically. The channel employed in this paper is the frequency-selective and fast Rayleigh fading channel, corrupted by cochannel interference (CCI) and additive white Gaussian noise (AWGN). Exact expressions for the probability distributions of the differential phase and amplitude ratio are derived for the BER calculation. The BER and optimum boundary are obtained for various channel conditions. In addition, the results for the BER in the presence of CCI are provided.

A new dynamic programming (DP) based algorithm for monotonic and continuous two-dimensional warping (2DW) is presented. This algorithm searches for the optimal pixel-to-pixel mapping between a pair of images subject to monotonicity and continuity constraints with by far less time complexity than the algorithm previously reported by the authors. This complexity reduction results from a refinement of the multi-stage decision process representing the 2DW problem. As an implementation technique, a polynomial order approximation algorithm incorporated with beam search is also presented. Theoretical and experimental comparisons show that the present approximation algorithm yields better performance than the previous approximation algorithm.

The conventional synthesis procedure of discrete time sparsely interconnected neural networks (DTSINNs) for associative memories may generate the cells with only self-feedback due to the sparsely interconnected structure. Although this problem is solved by increasing the number of interconnections, hardware implementation becomes very difficult. In this letter, we propose the DTSINN system which stores the 2-dimensional discrete Walsh transforms (DWTs) of memory patterns. As each element of DWT involves the information of whole sample data, our system can associate the desired memory patterns, which the conventional DTSINN fails to do.

There are two dynamics issues in vision chips: (i) The temporal dynamics issue due to the parasitic capacitors in a CMOS chip, and (ii) the spatial dynamics issue due to the regular array of processing elements in a chip. These issues are discussed in [1]-[3] for the resistor network with only associated parasitic capacitances. However, in this paper we consider also parasitic inductances as well as parasitic capacitances for a more precise network dynamics model. We show that in some cases the temporal stability condition for the network with parasitic inductances and capacitances is equivalent to that for the network with only parasitic capacitances, but in general they are not equivalent. We also show that the spatial stability conditions are equivalent in both cases.

The authors report on a 22-Gbit/s static decision IC fabricated with 0. 12-µm GaAs MESFETs. The key to attaining high-speed decision IC is the employment of a novel high-speed D-type flip-flop (D-FF). The D-FF succeeds in faster operation through the simplification of the circuitry and the reduction of the transition time of the output voltages.

Computational sensor (smart sensor, vision chip in other words) is a very small integrated system, in which processing and sensing are unified on a single VLSI chip. It is designed for a specific targeted application. Research activities of computational sensor are described in this paper. There have been quite a few proposals and implementations in computational sensors. Firstly, their approaches are summarized from several points of view, such as advantage vs. disadvantage, neural vs. functional, architecture, analog vs. digital, local vs. global processing, imaging vs. processing, new processing paradigms. Then, several examples are introduced which are spatial processings, temporal processings, A/D conversions, programmable computational sensors. Finally, the paper is concluded.

Wavelength division multiplex (WDM) photonic networks are expected as the key for the global communication infrastructure. Recent increase of communication demands require large-scale highly-dense WDM systems, which results in severe requirements for optical cross-connect systems, such as cross-talk specification. In this paper, we propose a new optical path cross-connect system (OPXC) using matrix-WDM scheme, which makes it possible to reduce cross-talk requirements of WDM filters and to construct OPXC in modular structures. The matrix-WDM scheme is a concept of two-layered optical paths, which provides wavelength group managements in the fiber dispersion equalization and EDFA gain equalization.

The tera-bit order capacity of ultrahigh-speed and wide-band networks will become necessary to provide highly advanced multimedia services. In conventional networks, electronic circuits limit the speed capability of the networks. Consequently, all-optical networks are essential to realize ultrahigh-speed and wide-band communications. In this paper, we propose the configuration of an all-optical code division multiplexing (CDM) switching network based on self-routing principles and the structure of a nonlinear all-optical switching device as one of the key components for the network. We show that the required performances of the optical devices used in the CDM switching fabric are lower than those used in the TDM and illustrate the basic transmission characteristics of the switching device utilizing FD-BPM. To evaluate the multiplexing performance, we demonstrate the maximum number of channels under an error-free condition and the BER characteristics when the Gold sequence is applied as one of the CDM code sets, and show that the network of the sub-tera-bit order capacity is realizable by adopting TDM, WDM and CDM technologies. We also illustrate the packet assembly method suitable for self-routing transmissions and one of network architectures where the proposed switching fabric can be exploited.