An inverse scattering problem in three dimensional two layered media is investigated. The shape and the location of the acoustic scatterer buried in one half-space are determined. With some a priori information, it becomes possible to solve this problem in three dimensions. Using the moment method, the scattered field is obtained for the estimated scatterer. An iterative procedure based on the Newton's method for the nonlinear least square problem is able to solve the inverse scattering problem. Some numerical results are presented.

The finite volume time domain (FVTD) method is applied to electromagnetic wave scattering from random rough dielectric surfaces. In order to gain a better understanding of physics of backscattering of microwave from rough surface, this paper treats both horizontal and vertical polarizations especially at low- grazing angle. The results are compared with those obtained by the Integral equation method and the small perturbation method as well as with the experimental data. We have shown that the present method yields a reasonable solution even at LGA. It should be noted that the number of sampling points per wavelength for a rough surface problem should be increased when more accurate numerical results are required, which fact makes the computer simulation impossible at LGA for a stable result. However, when the extrapolation is used for calculating the scattered field, an accurate result can be estimated. If we want to obtain the ratio of backscattering between the horizontal and vertical polarization, we do not need the large number of sampling points.

A delay-optimal technology mapping algorithm is developed on a general model of FPGA with hard-wired non-homogeneous logic block architectures which is composed of different sizes of look-up tables (LUTs) hard-wired together. This architecture has the advantages of short delay of hard-wired connections and area-efficiency of non-homogeneous structure. The Xilinx XC4000 is one commercial example, where two 4-LUTs are hard-wired to one 3-LUT. In this paper, we present a two-dimensional labeling approach and a level-2 node cut algorithm to handle the hard-wired feature. The experimental results show that our algorithm generates favorable results for Xilinx XC4000 CLBs. Over a set of MCNC benchmarks, our algorithm produces results with 17% fewer CLB depth than that of FlowMap in similar CPU time on average, and with 4% fewer CLB depth than that of PDDMAP on average while PDDMAP needs 15 times more CPU time.

A signal processing approach is discussed which has the potential for imaging strongly scattering objects from a series of scattering experiments. The method is based on a linear spectral estimation technique to replace the filtered backpropagation for limited discrete data and a subsequent nonlinear signal processing step to remove the contribution of multiple scattering my means of homomorphic filtering. Details of this approach are discussed and illustrated by applying the imaging algorithm to both simulated and real data.

In this paper we report the results of a study regarding the backscattering from wind-roughened water surfaces. The reference profile data has been deducted by an experiment held at the University of Heidelberg circular wave tank facility. The scattering theory is based on a fractal description of the surface and a combined use of the Kirchhoff approximation and the small perturbation method (SPM). The scattering results are tested versus the ones obtained via the periodic-surface moment method. The study shows the reliability of the novel approach.

To make clear numerically the scattering characteristics for a body embedded in a random medium, we need to analyze the bistatic cross-section (BCS). The scattering problem can be analyzed as a boundary value problem by using current generator method. The fourth moment of Green's functions in the random medium, which is necessary for the analysis, is obtained approximately by two-scale method. We analyze numerically the BCS of conducting circular cylinders in continuous random media, which are assumed to fluctuate about the dielectric constant of free space. The numerical results agree well with the law of energy conservation. The effects of random media on the BCS are also clarified numerically.

We call a network an anonymous network, if each vertex of the network is given no ID's. For distributed algorithms for anonymous networks, solvable problems depend strongly on the given initial conditions. In the past, initial conditions have been investigated, for example, by computation given the number of vertices as the initial condition, and in terms of what initial condition is needed to elect a leader. In this paper, we study the relations among initial conditions. To achieve this task, we define the relation between initial conditions A and B (denoted by A B) as the relation that some distributed algorithm can compute B on any network satisfying A. Then we show the following property of this relation among initial conditions. The relation is a partial order with respect to equivalence classes. Moreover, over initial conditions, it induces a lattice which has maxima and minima, and contains an infinite number of elements. On the other hand, we give new initial conditions k-LEADER and k-COLOR. k-LEADER denotes the initial condition that gives special condition only to k vertices. k-COLOR denotes the initial condition that divides the vertices into k groups. Then we investigate the property of the relation among these initial conditions.

This paper deals with the scattering problem of a layer where many spherical lossy particles of high dielectric constant are randomly distributed. A radiative transfer equation is used to calculate the scattering cross section of the layer. Four different multiple scattering methods are applied to determine the coefficients of the equation. The scattering cross sections of the four methods are compared by changing the incident angle and polarization of incident waves and the layer thickness. The comparison shows that the scattering cross section fairly depends on the multiple scattering methods and that we need to use an appropriate multiple scattering method for a scattering problem when using a radiative transfer equation.

In this paper, the electromagnetic scattering from a cylinder with a computer-generated random rough surface is analyzed by a numerical simulation method. The validity of the proposed numerical method is confirmed by comparing the present numerical results with those calculated by the perturbation method to second order and its Pade approximation. It is shown that the present proposed method can be applied to the case where the surface roughness becomes relatively large.

In this paper, we define content-identifier (ContentID) to represent the characteristics of shot. The ContentID carries both positional and temporal color information. Based on the concept of ContentID, we propose a video retrieval method. The method is robust to compression, format conversion, frame dropping and noise such as watermark and so on. Furthermore, based on our retrieval method, we implemented a copyright protection system for digital video using spread-spectrum based watermarking technique.

We present a result on the robust stabilization of uncertain nonlinear systems via applying feedback linearization. The allowable size of uncertainty is derived for stability. Based on that, we propose a technique that allows us to handle nonlinear systems which are not input-state linearizable. The usefulness of the technique is illustrated by numerical examples.

We discuss human collaborative discovery processes using a production system model as a cognitive simulator. We have developed an interactive production system architecture to construct the simulator. Two production systems interactively find targets in which the only experimental results are shared; each does not know the hypothesis the other system has. Through this kind of interaction, we verify whether or not the performance of two systems interactively finding targets exceeds that of two systems independently finding targets. If we confirm the superiority of collaborative discovery, we approve of emergence by the interaction. The results are: (1) generally speaking collaboration does not produces the emergence defined above, and (2) as the different degree of hypothesis testing strategies that the two system use gets larger, the benefits of interaction gradually increases.

Recently, two approaches investigated indexing and retrieving videos. One approach utilized the visual features of individual objects, and the other approach exploited the spatio-temporal relationships between multiple objects. In this paper, we integrate both approaches into a new video model, called the Visual-Spatio-Temporal (VST) model to represent videos. The visual features are modeled in a topological approach and integrated with the spatio-temporal relationships. As a result, we defined rich sets of VST relationships which support and simplify the formulation of more semantical queries. An intuitive query interface which allows users to describe VST features of video objects by sketch and feature specification is presented. The conducted experiments prove the effectiveness of modeling and querying videos by the visual features of individual objects and the VST relationships between multiple objects.

A novel residue arithmetic algorithm using radix-2 signed-digit (SD) number representation is presented. By this representation, memoryless residue arithmetic circuits using SD adders can be implemented. Conventional residue arithmetic circuits have been designed using binary number arithmetic system, but the carry propagation arises which limits the speed of arithmetic operations in residue modules. In this paper, a p-digit radix-2 SD number system is introduced to simplify the residue operation. For a modulus m, 2p-1 m 2p+2p-1-1, in a residue number system (RNS), the modulo m addition is performed by using two p-digit SD adders, one for the addition and one for the residue operation. Thus, the modulo m addition time is independent of the word length of operands. When m=2p or m= 2p 1, the modulo m addition is implemented by using only one SD adder. Moreover, a modulo m multiplier is constructed using a binary modulo m SD adder tree, and the modulo m multiplication can be performed in a time proportional to log 2 p. The VHDL implementation method for the presented algorithm is also discussed. The design and simulation results of some residue arithmetic circuits show that high speed residue arithmetic circuits can be obtained by the presented algorithms.

The signed regressor algorithm, a variation of the least mean square (LMS) algorithm, is characterized by the estimation way of using the clipped reference signals, namely, its sign (). This clipping, equivalent to quantizing the reference signal to 1, only increases the estimation error by about 2 dB. This paper proposes to increase the number of the quantization steps to three, namely, 1 and 0, and shows that the 'tri-quantized-x' normalized least mean square (NLMS) algorithm with three quantization steps improves the convergence property.

In the beginning of the new century, many information appliance (IA) products will replace traditional electronic appliances to help people in smart, efficient, and low-cost ways. These successful products must be capable of communicating multimedia information, which is embedded into the electronic appliances with high integration, innovation, and power-throughput tradeoff. In this paper, we develop a codesign procedure to analyze, compare, and emulate the multimedia communication applications to find the candidate implementations under different criteria. The experimental results demonstrate that in general, memory technology dominates the optimal tradeoff and ALU improvements impact greatly on particular applications. The results also show that the proposed procedure is effective and quite efficient.

In this letter we propose a filter for extracting a quasi-periodic signal from a noisy observation using wavelets. It is assumed that the instantaneous frequency of the signal is known. A particularly difficult task when the frequency and amplitude of the desired signal are varying with time is shown. The proposed algorithm is compared with three other methods.

In the future Internet, hierarchically classified Quality of Service (QOS) controls will be effective because various connections requiring different QOS are mixed. However, even in such an environment, among the same class connections, performance protection to harmful impact from the other connections and quality differentiation between connections will be required furthermore. In this paper, from this point of view, we focus on the active connections succession time (age of active connections) as a new dimensional criterion for buffer controls. To be concrete, the packet discarding control of congested router's buffer based on active connections is proposed. Moreover, its performance is evaluated through TCP/IP level simulation from the viewpoint of file transfer time. Conventional Internet can be regarded as the environment where only one class traffic exists (unit class environment). The proposed control scheme can provide powerful differentiation capability to avoid the performance disruption of total connections even in the conventional Internet.

Borehole radar is known as a powerful technique for monitoring of subsurface structures such as water flow. However, conventional borehole radar systems are operated in the frequency range lower than 100 MHz and the resolution is poor to measure a surface roughness and an inner structure of subsurface fractures directly. In order to monitor the water flow, these characteristics of subsurface fractures are important. We developed a polarimetric borehole radar system using dipole antennas and axial slot antennas and have found that this system can provide more information than conventional borehole radar. However, the relationship between the characteristic of subsurface fracture and the measured polarimetric radar information has not been clear. In this paper, we simulate electromagnetic wave scattering from subsurface fractures having a rough surface by Finite-Difference Time-Domain (FDTD) technique and discuss the relationship between a surface roughness of subsurface fracture and the polarimetric information. It is found that the subsurface fracture having strong cross-polarized components can be estimated to be rough surface fracture. The full polarimetric single-hole radar measurement was carried out at the Mirror Lake site, NH, USA. In this experiment, we found that subsurface fractures can be classified into some groups by an energy scattering matrix, and found that the subsurface fracture estimated to have a rough surface corresponds to that has higher water permeability.

Methods for implementing SS7 functions are proposed for a large-capacity decentralized switching node; they satisfy the condition of hiding distributed configurations from adjacent nodes. First, line accommodation and acquisition methods are clarified for a large-capacity switching node in which multiple modules are used to realize trunk circuits and SS7 signaling links. Two methods are then proposed for allocating SS7 functions within the switching node. One distributes the functions over multiple circuit-switched modules (distributed allocation) while the other centralizes the functions in dedicated signaling modules (centralized allocation). We quantitatively evaluate both methods in terms of node scale versus the number of modules and signaling links required, the inter-module data transfer rate required, and the node traffic handling capacity when a particular module fails. From the evaluation results, we show that the distributed allocation should be employed for small-scale nodes and the centralized allocation for large-scale nodes. We also show the effectiveness of a method for avoiding a characteristic problem that arises when a particular module fails. Finally, we implement an experimental system as an example.