This paper presents a new efficient method for finding an "optimal" bi-decomposition form of a logic function. A bi-decomposition form of a logic function is the form: f(X) = α(g1(X1), g2(X2)). We call a bi-decomposition form optimal when the total number of variables in X1 and X2 is the smallest among all bi-decomposition forms of f. This meaning of optimal is adequate especially for the synthesis of LUT (Look-Up Table) networks where the number of function inputs is important for the implementation. In our method, we consider only two bi-decomposition forms; (g1 g2) and (g1 g2). We can easily find all the other types of bi-decomposition forms from the above two decomposition forms. Our method efficiently finds one of the existing optimal bi-decomposition forms based on a branch-and-bound algorithm. Moreover, our method can also decompose incompletely specified functions. Experimental results show that we can construct better networks by using optimal bi-decompositions than by using conventional decompositions.

The problem of electromagnetic scattering caused by inductive discontinuities locate in parallel-plate waveguides, in particular when dealing with discontinuous conductors of finite thickness, is analyzed using the modified residue-calculus method, the equations suitable for a numerical calculation are derived. The incident wave is taken to be the dominant mode, and the reflection and transmission properties of a symmetrical inductive iris are discussed.

In this paper, a transceiver VLSI architecture is proposed for high speed digital CATV modems, which can perform both the QAM and the VSB transmissions. The proposed architecture of all-digital dual-mode QAM/VSB receiver consists of digital AGC, digital demodulator, fractionally spaced blind equalizer and DFE, digital carrier recovery, and symbol timing recovery. Finite word-length simulation results show that the proposed architecture can achieve an SNR 29 dB for both the 64-QAM mode and 8-VSB mode when the 10 bit ADC input signal SNR is 36 dB, and there are 6 kHz of carrier frequency offset, 110 ppm of symbol rate offset, and -82 dBc carrier phase-jitter at 10 kHz away from the nominal carrier frequency.

A method of visualization of multimodal images by one monochromatic image is presented on the basis of the projection pursuit approach of the inverse process of the anisotropic diffusion which is a method of image restoration enhancing contrasts at edges. The extension of the projection from a linear one to nonlinear sigmoidal functions enhances the contrast further. The deterministic annealing technique is also incorporated into the optimization process for improving the contrast enhancement ability of the projection. An application of this method to a pair of MRI images of brains reveals its promising performance of superior visualization of tissues.

Simple disjunctive decomposition is a special case of logic function decompositions, where variables are divided into two disjoint sets and there is only one newly introduced variable. It offers an optimal structure for a single-output function. This paper presents two techniques that enable us to apply simple disjunctive decompositions with little overhead. Firstly, we propose a method to find symple disjunctive decomposition forms efficiently by limiting decomposition types to be found to two: a decomposition where the bound set is a set of symmetric variables and a decomposition where the output function is a 2-input function. Secondly, we propose an algorithm that constructs a new logic representation for a simple disjunctive decomposition just by assigning constant values to variables in the original representation. The algorithm enables us to apply the decomposition with keeping good structures of the original representation. We performed experiments for decomposing functions and confirmed the efficiency of our method. We also performed experiments for restructuring fanout free cones of multi-level logic circuits, and obtained better results than when not restructuring them.

In many embedded systems, a significant amount of power is consumed for off-chip driving because off-chip capacitances are much larger than on-chip capacitances. This paper proposes instruction scheduling techniques to reduce power consumed for off-chip driving. The techniques minimize the switching activity of a data bus between an on-chip cache and a main memory when instruction cache misses occur. The scheduling problem is formulated and two scheduling algorithms are presented. Experimental results demonstrate the effectiveness and the efficiency of the proposed algorithms.

The importance of technology retargeting for hard IPs is getting increased. However, recent advances in process technologies make layout reuse too complicated to be done by conventional compactors. As an efficient approach, this paper proposes a flexible layout abstraction model and a new layout synthesis algorithm. The synthesis algorithm provides a concurrent procedure of detailed wiring, compaction, and transistor layout generation by using a scan line to get better layout results than conventional compactors. We have applied this method to the technology retargeting of actual cell layouts and have achieved quite good results comparable to hand-crafted designs.

A fuel cell energy system is under development for supply of generated electrical energy to telecommunications equipment. It is a cogeneration system; the heat energy recovered is used to cool the telecommunications equipment. For this system, a method is described for controlling a new DC interconnection converter. Its DC interconnection characteristics are also discussed. The new converter controls its input current to the fuel cell rated current at maximum and can operate stably even when the fuel cell voltage decreases. This allows good DC interconnection characteristics to be obtained in both the steady state and the transient state.

Voice activity detection (VAD) is to determine whether a short time speech frame is voice or silence. VAD is useful in reducing the mean speech coding rate by suppressing transmission during silence periods, and is effective in transmitting speech and other data simultaneously. This letter describes a VAD system that uses a neural network. The neural network gets several parameters by analyzing slices of the speech wave form, and outputs only one scalar value related to voice activity. This output is compared to a threshold to determine whether the slice is voice or silence. The mean code transfer rate can be reduced to less than 50% by using the proposed VAD system.

There is increasing demand for corporate information systems that have a simple human interface and are easy to access via WWW browsers. This paper proposes WebBASE, which integrates the WWW and relational databases. Experimental evaluation shows that WebBASE offers superior performance compared to existing products. Field studies of actual WebBASE applications show that it can improve the productivity of software developers for intranet application development.

A fractal image coding scheme using classified range regions is proposed. Two classes of range regions, shade and nonshade, are defined here, A shade range region is encoded by the average gray level, while a nonshade range region is encoded by IFS parameters. To obtain classified range regions, the two-stage block merging scheme is proposed. Each range region is produced by merging primitive square blocks. Shade range regions are obtained at the first stage, and from the rest of primitive blocks nonshade range regions are obtained at the second stage. Furthermore, for increasing the variety of region shape, the 8-directional block merging scheme is defined by extension of the 4-directional scheme. Also, two similar schemes for encoding region shapes, each corresponding to the 4-directional block merging scheme and the 8-directional block merging scheme, are proposed. From the results of simulation by using a test image, it was demonstrated that the variety of region shape allows large shade range regions to be extracted efficiently, and these large shade range regions are more effective in reduction of total amount of codebits with less increase of degradation of reconstructed image quality than large nonshade range regions. The 8-directional merging and coding scheme and the 4-directional scheme reveal almost the same coding performance, which is improved than that of the quad-tree partitioning scheme. Also, these two schemes achieve almost the same reconstructed image quality.

A computational cost reduction scheme for a post-distortion type nonlinear distortion compensator of OFDM signals is proposed, and compared with the conventional sub-optimum detection scheme. The proposed scheme utilizes the principle that a complex OFDM signal can be demodulated with not only both I-phase (real part) and Q-phase (imaginary part) components, but also either of them. Usually each phase of an OFDM signal exhibits different signal envelope and they are distorted differently by the nonlinearity of a power amplifier. Consequently, three output sequence patterns can be obtained at the receiver. By comparing these outputs, we can know the erroneous positions of these sequences to some extent. By the aid of this comparison, we need to evaluate only a limited number of replicas for the compensation process of the post-distortion type nonlinear distortion compensator, which results in the computational cost reduction. We have proposed four new compensation schemes based on this idea and derived their performance in terms of the bit error rate and the average number of calculations.

In this paper, millimeter-wave radar cross section (RCS) characteristics for rough surface is investigated by means of an approximation method of the magnetic field integral equation and the feasibility of road condition sensing is discussed. The RCS measurement at 94 GHz is carried out in order to verify the numerical result, thereby the numerical results are in good agreement with the measured RCS. The dependence of RCS on the radar incidence angle and surface roughness is investigated where the cross-polarized RCS characteristic is also considered.

Providing various assistances for design modifications on HDL source codes is important for design reuse and quick design cycle in VLSI CAD. Program slicing is a software-engineering technique for analyzing, abstracting, and transforming programs. We show algorithms for extracting/removing behaviors of specified signals in VHDL descriptions. We also describe a VHDL slicing system and show experimental results of efficiently extracting components from VHDL descriptions.

In this paper, we present an analysis of the microstrip lines whose strip conductors are of various cross-sections, such as rectangular cross-section, triangle cross-section, and half-cycle cross-section. The method employed is the boundary integral equation method (BIEM). Numerical results for these microstrip lines demonstrate various shape effects of the strip conductor on the characteristics of lines. The processing technique on the convergence of the Green's function is also described.

Retrieving the unknown parameters of scattering objects from measured field data is the subject of microwave imaging. This is naturally and usually posed as an optimization problem. In this paper, micro genetic algorithm coupled with deterministic method is applied to the shape reconstruction of perfectly conducting cylinders. The combined approach, with a very small population like the micro genetic algorithm, performs much better than the conventional large population genetic algorithms (GA's) in reaching the optimal region. In addition, we propose a criterion for switching the micro GA to the deterministic optimizer. The micro GA is utilized to effectively locate the vicinity of the global optimum, while the deterministic optimizer is employed to efficiently reach the optimum after inside this region. Therefore, the combined approach converges to the optimum much faster than the micro GA. The proposed approach is first tested by a function optimization problem, then applied to reconstruct perfectly conducting cylinders from both synthetic data and real data. Impressive and satisfactory results are obtained for both cases, which demonstrate the validity and effectiveness of the proposed approach.

In this work, we propose an End-to-End Rate Control Approach (EERCA) for congestion avoidance in Available Bit Rate (ABR) service on Asynchronous Transmit Mode (ATM) networks. In our approach, the network estimates the number of cells stored in the switch for each VC. The source generates a specific traffic pattern, then a proper explicit rate can be derived based on the received traffic pattern at the destination. This approach is designed to reduce the rate calculation effort in the switch as well as to avoid the complexity in setting the monitoring-interval. EERCA features higher efficiency, higher utilization, more stable queue occupancy, shorter transient response time, and better fairness compared with existed schemes.

This paper shows an analysis of electromagnetic scattering from an open-ended rectangular cylinder for a plane wave incidence. The internal region is separated into two areas by additional plates to investigate the cavity resonance in detail. The applied numerical technique is the point matching method taking account of the edge condition. As numerical examples, the radar cross section is presented for E - polarized case and H - polarized case. Physical meanings of the computational results are discussed with a view to the contribution of the iris.

This paper describes a new method for permittivity measurement using microwave free-space technique. The general consideration is to measure the amplitudes of transmission and reflection coefficients and calculate the permittivity from the measurement values. Theoretical analysis shows that the permittivity of the sample can be calculated solely from the measurement values of the amplitudes of transmission and reflection coefficients when the sample is prepared with so large attenuation that the multiple reflections between the two surfaces of the sample can be neglected. Using this method, the permittivity measurement can be performed without reflection influence, and on-line measurement of the permittivity becomes possible because the permittivity can be measured instantaneously and without contact with the material.

This paper presents a new compound constructive algorithm of neural networks whereby the fuzzy logic technique is explored as an efficient learning algorithm to implement an optimal network construction from an initial simple 3-layer network while the genetic algorithm is used to help design an improved network by evolutions. Numerical simulations on artificial life demonstrate that compared with the existing network design algorithms such as the constructive algorithms, the pruning algorithms and the fixed, static architecture algorithm, the present algorithm, called FuzGa, is efficient in both time complexity and network performance. The improved time complexity comes from the sufficiently small 3 layer design of neural networks and the genetic algorithm adopted partly because the relatively small number of layers facilitates an utilization of an efficient steepest descent method in narrowing down the solution space of fuzzy logic and partly because trappings into local minima can be avoided by genetic algorithm, contributing to considerable saving in time in the processing of network learning and connection. Compared with 54. 8 minutes of MLPs with 65 hidden neurons, 63. 1 minutes of FlexNet or 96. 0 minutes of Pruning, our simulation results on artificial life show that the CPU time of the present method reaching the target fitness value of 100 food elements eaten for the present FuzGa has improved to 42. 3 minutes by SUN's SPARCstation-10 of SuperSPARC 40 MHz machine for example. The role of hidden neurons is elucidated in improving the performance level of the neural networks of the various schemes developed for artificial life applications. The effect of population size on the performance level of the present FuzGa is also elucidated.