In cryptography, we want a Boolean function which satisfies PC(l) of order k for many (l,k). Let PCn(l,k) be a set of Boolean functions with n input bits satisfying PC(l) of order k. From a view point of construction, it is desirable that there exists (l0,k0) such that PCn(l0, k0) PCn(li,ki) for many i 1. In this paper, we show a negative result for this problem. We prove that PCn(l1,k1) PCn(l2,k2) for a large class of l1, k1, l2 and k2.

In a wireless OFDM-CDMA system, the data-modulated symbol of each user is spread over multiple subcarriers in the frequency domain using a given spreading code. For the downlink (base-to-mobile) transmissions, a set of orthogonal spreading codes defined in the frequency domain is used so that different users data can be transmitted using the same set of subcarriers. The frequency selectivity of the radio channel produces the orthogonality destruction. There are several frequency equalization combining techniques to restore orthogonality, i.e., orthogonal restoration combining (ORC), control equalization combining (CEC) that is a variant of ORC, threshold detection combining (TDC), and minimum mean square error combining (MMSEC). The ORC can restore orthogonality among users but produces noise enhancement. However, CEC, TDC, and MMSEC can balance the orthogonality restoration and the noise enhancement. In this paper, we investigate, by means of computer simulation, how the BER performances achievable with ORC, CEC, TDC, and MMSEC are impacted by the propagation parameters (path time delay difference and fading maximum Doppler frequency), number of users, pilot power used for channel estimation, and channel estimation scheme. To acquire a good understanding of ORC, CEC, TDC, and MMSEC, how they differ with respect to the combining weights is discussed. Also, the downlink transmission performances of DS-CDMA and OFDM-CDMA are compared when the same transmission bandwidth is used. How much better performance is achieved with OFDM-CDMA than with DS-CDMA using ideal rake combining is discussed.

This paper provides a M+1-st price auction scheme using homomorphic encryption and the mix and match technique; it offers secrecy of bidding price and public verifiability. Our scheme has low round communication complexity: 1 round from each bidder to auctioneer in bidding and log p rounds from auctioneer to trusted authority in opening when prices are selected from p prefixed choices.

The capability of a high-temperature superconducting sigma-delta modulator was studied by means of circuit simulation and FFT analysis. Parameters for the circuit simulation were extracted from experimental measurements. The present circuit simulation includes thermal-noise effect. Successive FFT analyses were made to evaluate the dynamic range of the sigma-delta modulator. As a result, the dynamic range was evaluated as 60.1 dB at temperature of 20 K and 56.9 dB at temperature of 77 K.

Due to saturable nature of gain or absorption of Er doped fiber, a dynamic grating is formed by standing wave produced by interference between two laser beams traveling in opposite directions in the fiber. In this letter, we propose a variable optical filter using the dynamic grating in Er doped fiber controlled by synthesis of optical coherence function. Simulations and experimental verifications are also shown.

There is a strong demand to expand captioned broadcasting for TV news programs in Japan. However, keyboard entry of captioned manuscripts for news program cannot keep pace with the speed of speech, because in the case of Japanese it takes time to select the correct characters from among homonyms. In order to implement simultaneous subtitled broadcasting for Japanese news programs, a simultaneous subtitling system by speech recognition has been developed. This system consists of a real-time speech recognition system to handle broadcast news transcription and a recognition-error correction system that manually corrects mistakes in the recognition result with short delay time. NHK started simultaneous subtitled broadcasting for the news program "News 7" on the evening of March 27, 2000.

In this paper we describe collaborative constraint functional logic programming and the system called Open CFLP that supports this programming paradigm. The system solves equations by collaboration of various equational constraint solvers. The solvers include higher-order lazy narrowing calculi that serve as the interpreter of higher-order functional logic programming, and specialized solvers for solving equations over specific domains, such as a polynomial solver and a differential equation solver. The constraint solvers are distributed in an open environment such as the Internet. They act as providers of constraint solving services. The collaboration between solvers is programmed in a coordination language embedded in a host language. In Open CFLP the user can solve equations in a higher-order functional logic programming style and yet exploit solving resources in the Internet without giving low-level programs of distributions of resources or specifying details of solvers deployed in the Internet.

This paper studies the optimization of signature waveforms and power allocation for synchronous code-division multiple access (CDMA) systems under the root-mean-square (RMS) bandwidth constraint. The optimization is considered for two types of receivers, namely the conventional matched filter (MF) receiver and the minimum mean-square error (MMSE) receiver. For both cases, the optimization criterion is to maximize the average signal to interference ratios (SIRs) at the receivers' outputs. For a given RMS bandwidth constraint and an arbitrary power allocation scheme, a procedure to obtain the optimal signature waveforms is provided. Based on this procedure, it is then shown that the optimal power allocation is achieved when all the received powers are equal. With the optimal power allocation, solutions for the optimal signature waveforms are presented and discussed in detail. It is also demonstrated that, compared to the previously obtained Welch-bound-equality (WBE) signature waveforms, the proposed signature waveforms can significantly improve the user performance.

This paper presents a novel and practical face-assisted video coding scheme to enhance the visual quality of the face region in videophone applications. A low-complexity skin-color-based face detection and tracking scheme is proposed to locate the human face regions in realtime. After classifying the macroblocks (MBs) into the face and non-face regions, we present a dynamic distortion-weighting adjustment (DDWA) scheme to skip encoding the static non-face MBs, and the saved bits are used to compensate the face region by increasing the distortion weighting of the face MBs. The quality of the face regions will thus be largely enhanced. Moreover, the computation originally required for encoding the skipped MBs can also be saved. The experimental results show that the proposed method can significantly improve the PSNR and the subjective quality of face regions, while the degradation introduced on the non-face areas is relatively invisible to human perception. The proposed algorithm is fully compatible with the H. 263 standard, and the low complexity feature makes it well suited to be implemented for real-time applications.

This paper shows an extensive software performance analysis of dedicated hash functions, particularly concentrating on Pentium III, which is a current dominant processor. The targeted hash functions are MD5, RIPEMD-128 -160, SHA-1 -256 -512 and Whirlpool, which fully cover currently used and future promised hashing algorithms. We try to optimize hashing speed not only by carefully arranging pipeline scheduling but also by processing two or even three message blocks in parallel using MMX registers for 32-bit oriented hash functions. Moreover we thoroughly utilize 64-bit MMX instructions for maximizing performance of 64-bit oriented hash functions, SHA-512 and Whirlpool. To our best knowledge, this paper gives the first detailed measured performance analysis of SHA-256, SHA-512 and Whirlpool.

A 3D display using super high-density multi-view images should enable reproduction of natural stereoscopic views. In the super multi-view display system, viewpoints are sampled at an interval narrower than the diameter of the pupil of a person's eye. With the parallax produced by a single eye, this system can pull out the accommodation of an eye to an object image. We are now working on a real-time view-interpolation system for the super multi-view 3D display. A multi-view camera using convergence capturing to prevent resolution degradation captures multi-view images of an object. Most of the data processing is used for view interpolation and rectification. View interpolation is done using a high-speed image-processing board with digital-signal-processor (DSP) chips or single instruction stream and multiple data streams (SIMD) parallel processor chips. Adaptive filtering of the epipolar plane images (EPIs) is used for the view-interpolation algorithm. The multi-view images are adaptively interpolated using the most suitable filters for the EPIs. Rectification, a preprocess, converts the multi-view images in convergence capturing into the ones in parallel capturing. The use of rectified multi-view images improves the processing speed by limiting the interpolation processing in EPI.

To improve the CT image degraded by radiographic noise (such as quantum mottle), we propose a method based on the wavelet transform modulus sum (WTMS). The noise and regular parts of a signal can be observed by tracing the evolution of its WTMS across scales. Our results show that most of the quantum mottle in the projections of Shepp-Logan phantom has been removed by the proposed method with the supposed cranium well preserved. The denoised CT images show good signal to noise ratio in the region of interest. We also have investigated the relation between the number of X-ray photons and the quality of images reconstructed from denoised projections. From experimental results, this method shows the possibility to reduce a patient's dose about 1/10 with the same visual quality.

The purpose of this paper is to derive a novel fractionally spaced Bayesian decision feedback equalizer (FS-BDFE). The oversampling technique changes single input single output (SISO) linear channel to single input multiple output (SIMO) linear channel. The Bayesian decision variable in the FS-BDFE is defined as the product of Bayesian decision variables in the Bayesian decision feedback equalizers (BDFE) corresponding to each channels of the SIMO. It can be shown that the FS-BDFE has less decision error probability than the conventional BDFE. The effectiveness of the proposed equalizer is also demonstrated by the computer simulation.

We describe a new automated method for detecting embedded objects in the ultrasonic non-destructive testing (NDT) system. A-scan waves collected by our developed system are converted into a B-scan image. The sensor system has the noise signals independent from targets to be detected. In the ultrasonic NDT system, the signals are due to disturbing of echoes produced by the transducers and multiple reflections. These signals are called inherent wave. This paper first proposes the estimation method of the inherent wave from the B-scan image. After this method subtracts the inherent wave, the resultant image (suppression image) is considered as the image consisting of only echoes from the embedded objects. Second, analysis of the intensity histogram of the suppression image leads the candidate points of embedded objects. Finally, fuzzy if-then rules can represent information on distribution of the intensity histogram and the homogeneous intensity levels of the objects. Evaluated degrees from the inference results can demonstrate the embedded objects. The method was applied to concrete members with reinforcing bars, resin tubes and steel pipes. The experimental results showed that this method was able to automatically detect the embedded objects with high accuracy and to display the location of embedded objects.

Adaptive beamforming, using the Conjugate Gradient Normal Equation Residual problem, is applied to a base station array, in the UTRA-TDD up-link. A Wideband Directional Channel Model is used, characterising specific micro-cell, street-type scenarios. These differ in the number of mobile terminals, grouped and placed along the street axis, and on their distances to the base station. Time- and angle-of-arrival spreads, and on-the-air interference content are the main parameters inherently varied and analysed. The average beamforming gain and signal-to-noise ratio are evaluated, also varying the number of array elements. The high number of arriving correlated and closely correlated signals, together with the composed nature of the correlation matrix in the algorithm's cost function, result in that other than the MMSE solutions may lead to the best interference suppression, for the tested scenarios. Among the several weighted interfering power components, the most relevant is due to the delayed signals from all the other links. The combination of the number of arriving orthogonal codes, time-of-arrival and angle-of-arrival spreads condition beamforming performance: the number of array elements affect performance, depending on the mobile terminal distance to the base station, and on the number of active links; for short distances and large number of users, larger time-of-arrival spread degrades beamformer performance, over the opposing effect of angle-of-arrival spread; the number of active users affects beamforming gain especially in the case that delay spreads are larger, i.e., for shorter mobile terminal distances to the base station.

The existing methods for reconstruction of a super-resolution image from undersampled and shubpixel shifted image sequence have two disadvantages. One is that most of them have to perform a lot of computations which lead to taking a lot of time and cannot meet the need of realtime processing. Another is that they cannot achieve satisfactory results in the case that the undersampling rate is too low. This paper considers applying a pyramid structure method to the super-resolution of the image sequence since it has some iterative optimization and parallel processing abilities. Based on the Iterative Back-Projection proposed by Peleg, a practical implementation, called Pyramid Iterative Back-Projection, is presented. The experiments and the error analysis show the effectiveness of this method. The image resolution can be improved better even in the case of severely undersampled images. In addition, the proposed method can be done in parallel and meet the need of real-time processing. The implementation framework of the method can be easily extended to the other general super-resolution methods.

We introduce stepwise resonant excitation by two-color optical near fields in order to detect Rb atoms with a slit-type detector. Blue fluorescence of the second D2 line is monitored for background-free detection. Feasibility of the method is shown from an experiment with a Rb vapor cell, where a sub-Doppler spectrum with the FWHM of 80 MHz is obtained. The detection efficiency is estimated at about 3% for cold Rb atoms.

This paper proposes and investigates a coding and decoding scheme to achieve adaptive channel coding using a Finite State Machine (FSM) for Software Defined Radio (SDR). Adaptive channel coding and decoding systems that can switch between different coding rates and error correcting capabilities in order to adapt to changing applications and environments, are effective for SDR. However, in these systems, a receiver cannot always select the correct decoder which causes decoding errors, usually referred to as Decoder-Selection-Errors (DSE). We propose a trellis encoder estimation scheme that compensates for this problem. This scheme uses the circuit of FSM to limit the encoder transition and the Viterbi algorithm for maximum likelihood trellis encoder estimation. Computer simulations are applied for evaluating the DSE rate, the Bit Error Rate (BER) and Throughput of the proposed scheme in comparison with a conventional scheme.

This paper develops a modular synthesis algorithm for timed circuits that is dramatically accelerated by partial order reduction. This algorithm synthesizes each module in a hierarchical design individually. It utilizes partial order reduction to reduce the state space explored for the other modules by considering a single interleaving of concurrently enabled transitions. This approach better manages the state explosion problem resulting in a more than 2 order of magnitude reduction in synthesis time. The improved synthesis time enables the synthesis of a larger class of timed circuits than was previously possible.

Using the finite-difference time-domain method, we evaluated the performance of apertured near-field fiber probes with a double-tapered structure, which have exhibited, in recent experiments, a much higher collection efficiency of localized light in comparison with single-tapered probes. We clarified that this high collection efficiency could be attributed to the shortening of the cutoff region, and the efficient coupling to the guiding mode of the optical fiber. By reproducing the experimental results in terms of the spatial resolution and the collection efficiency as a function of the aperture diameter, our calculation was confirmed to be valid and useful for the design of probes in a variety of applications.