Electronics and Communications in Japan (Part III: Fundamental Electronic Science)最新文献

When synchronization phenomena are analyzed, the phase equations are known to often provide useful qualitative and quantitative information [1]. The target of this paper is to examine through comparisons of the derivation algorithm of the phase equations a realistic system including the case where the equations are not necessarily given explicitly. In other words, the equivalence of two different conventional algorithms [1, 4] is shown, and the advantages and cautions when specific phenomena use both in an example are each explained. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(12): 1– 9, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20284

Existing data-driven processors offer the advantages of being able to naturally resolve the problems inherent in a wide variety of granularities of parallelism, and of being able to multiprocess without overhead. However, because an instruction is not issued until the instruction that generates the source operand finishes executing, a delay equal to the number of stages in the pipeline occurs before an instruction that has a data-dependency relationship can be executed. As a result, portions of sequential processing in a program become a bottleneck. The authors are therefore in the process of developing an LSI processor that is able to retain the advantages of conventional data-driven processors while being able to efficiently execute blocks of sequential processing. This paper presents and evaluates the performance of the proposed execution model and pipeline structure of this processor. This processor uses the same pipeline to perform instruction level multiprocessing of data-driven programs that issue instructions based on the data-dependency relationships and control-driven programs that issue instructions sequentially based on a program counter. The effectiveness of parallel processing by data-driven programs, improvements in the efficiency of sequential processing by introducing control-driven programs, and the ability to evenly share the pipeline when data-driven and control-driven programs are multiprocessing are evaluated. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(12): 36–49, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20358

Various kinds of methods have been proposed for hardware module interface verification. We focus on monitor-based formal verification. In our approach, to verify interface specifications more comprehensively, we describe specifications of a module interface in a specification language based on regular expressions, and then behavioral models are constructed. Next, a monitor circuit is generated. This method prevents monitor circuits from involving errors because of automated monitor generation. Usually, input constraints must also be given for a design, when each module is verified one by one, because undesirable input patterns may be provided. Instead of giving input constraints, we propose a method of monitor generation including input constraints. Input constraints are extracted from specification of interfaces. Therefore, verification of individual modules becomes less difficult. We show an experimental result on formal verification of circuits compliant to the AMBA AHB bus protocol. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(12): 19–26, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20360

In this paper, the authors propose a method of systematically generating 3-colorable (3COL) graph instances for which a great deal of time and effort are required to obtain a solution (or to determine solvability). This method, which differs from the conventional approach of selecting hard instances from among randomly generated instances, aims to reliably generate hard problems by repeatedly embedding 3COL minimal unsolvable structures in the initial graph. The generated instances conform to various conditions of problems for which the solution searches that had been identified conventionally are extremely difficult. Also, the authors use several solution search algorithms to experimentally verify that the required effort is an exponential order of the number of vertices. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(12): 27–35, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20359

We used ultrasound exposure to perform disaggregation and surface modification of aggregated nano-diamond particles. We formed a standing-wave sound field using a Langevin transducer to drive a stainless-steel vibrating disk installed at the bottom of a water tank, and generated efficient acoustic cavitation. With 20 minutes of ultrasonic exposure, we were able to reduce aggregated nano-diamond particles with average particle diameters of 5µm to average particle diameters of 100 nm or less. We also confirmed that we had improved the zeta potential, an index of surface modification, by a factor of more than two. Furthermore, we used a hydrophone to measure the sound field inside the water tank, and calculated the average acoustic intensity at 800W/m² or more to demonstrate that the nano-diamond surfaces had been modified. We confirmed that the zeta potential and average particle diameter of the nano-diamonds could be maintained for at least 150 days after ultrasound exposure. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(12): 10– 18, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20268

Visual servoing is being widely investigated as a robot control method that is robust to unpredictable disturbances. Conventional visual servoing assumes calibration of the robot and camera, but such calibration proves very difficult in practice. Thus, we have proposed a method of stable visual servoing for a robot moving on a plane, with neither the robot nor its camera being calibrated. In this paper, we extend the previous method to 3D projective space, thus providing visual servoing for general uncalibrated robots operated in 3D space. In particular, we show that invariant properties in projective space defined by means of epipolar geometry play an important role in navigation. © 2007 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(12): 50–58, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20361