電気学会論文誌C(電子・情報・システム部門誌)
Online ISSN : 1348-8155
Print ISSN : 0385-4221
ISSN-L : 0385-4221
128 巻, 7 号
選択された号の論文の33件中1~33を表示しています
特集:平成19年電気学会電子・情報・システム部門大会
特集論文
<医用電子・生体工学>
  • Sheng Ge, Makoto Ichikawa, Atsushi Osa, Keiji Iramina, Hidetoshi Miike
    2008 年 128 巻 7 号 p. 1015-1022
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    In this study, we examined the spatial and temporal frequency tuning of motion-in-depth aftereffect. We changed the spatial frequency of test stimuli and temporal frequency of adapting stimuli to investigate the influence on the motion aftereffect duration. It was found that, in spite of the change of spatial frequency of test stimuli, the maximum motion aftereffect duration was measured when the mean temporal frequency of adapting stimuli was set to 3.83 Hz. On the other hand, in spite of the change of temporal frequency of adapting stimuli, the maximum motion aftereffect duration was measured when the mean spatial frequency of test stimuli was set to 0.40 cycles/degree. We also changed the moving direction of adapting stimuli in approaching and receding directions to investigate the moving direction influence on the motion aftereffect duration. It was noted that compared to the approaching motion, longer motion aftereffect duration was measured for the receding motion.
  • 加納 尚之, 佐久間 研司, 中島 健二
    2008 年 128 巻 7 号 p. 1023-1028
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Amyotrophic Lateral Sclerosis(ALS) patients are unable to successfully communicate their desires, although their mentality is normal, and so, the necessity of Communication Aids(CA) for ALS patients is realized. Therefore, the authors are focused on Event-Related Potential(ERP) which is elicited primarily for the target by visual and auditory stimuli. P200, N200 and P300 are components of ERP. These are potentials that are elicited when the subject focuses attention on stimuli that appears infrequently. ALS patient participated in two experiments. In the first experiment, a target word out of five words on a computer display was specified. The five words were linked to an each electric appliance, allowing the ALS patient to switch on a target appliance by ERP. In the second experiment, a target word in a 5×5 matrix was specified by measure of ERP. The rows and columns of the matrix were reversed randomly. The word on a crossing point of rows and columns including the target word, was specified as the target word. The rate of correct judgment in the first and second experiments were 100% in N200 and 96% in P200. For practical use of this system, it is very important to determine suitable communication algorithms for each patient by performing these experiments evaluating the results.
  • 高嶋 一登, 釜道 紀浩, 八木 透, 安積 欣志, 向井 利春
    2008 年 128 巻 7 号 p. 1029-1035
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Ionic polymer-metal composite (IPMC) is a promising material in biomedical actuators and sensors because IPMC is soft and flexible, leading to the safety of the device itself. The purpose of this study is to investigate the biocompatibility of IPMC by in vitro experiments, in order to evaluate the applicability in biomedical fields. In addition to an IPMC specimen prepared by the conventional “impregnation-reduction method” using cationic gold complexes and reducing agents, two specimens were prepared by processes in addition to that used for the conventional IPMC specimen. One specimen was reduced in Na2SO3 solution and another specimen was cleaned in H2O2 solution. Colony-forming test using Chinese hamster V79 cells shows high cytotoxicity of all IPMC specimens. Examination of direct inlet mass spectrometry (DI-MS) revealed that the peak intensity of gold complex (particularly, m/z=180) was different from that of Nafion film. Monitoring the peak at m/z=180 showed a remnant with the structure of phenanthroline in IPMC specimens which were not cleaned in H2O2 solution.
  • 服部 昌平, 硯川 潤, 神崎 亮平, 神保 泰彦, 濱口 哲也, 高橋 宏知, 中尾 政之
    2008 年 128 巻 7 号 p. 1036-1042
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Information transfer among neuronal populations has directional bias. Some past studies demonstrated that microstructure can bias a direction of information transfer at a cellular level. However the transfer at a population level has been hardly controlled to date. Here, in order to control the information transfer we attempt to bias direction of neurite outgrowth of cultured neurons with a three-dimensional asymmetric microstructure. The proposed microstructure is an embossed barrier with a rectangular-triangle cross section, namely an ascending slope and vertical wall. Because of the asymmetricity, a neurite growth rate from the wall-side to slope-side is expected to be suppressed as compared with that of slope-to-wall. We fabricated the microstructure on a polystyrene substrate by hot press, simultaneously embedding line-electrodes for probing stimulation. To confirm impact of the microstructure on neurite outgrowth, and thus signal transfer direction between neuronal populations separated by the structure, we stimulated cultured neurons on the both sides of the structure. There was difference in neuronal responses to wall-side stimulation and slope-side one, demonstrating the directional characteristic of information transfer.
  • 硯川 潤, 神崎 亮平, 中尾 政之, 神保 泰彦, 高橋 宏知
    2008 年 128 巻 7 号 p. 1043-1049
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Light addressing is an emerging technique to optically address a virtual electrode on a photoconductive substrate. A thinner photoconductive layer of a light-addressable planar electrode can improve the spatial resolution of the light-addressed electrode. Voltage application to the electrode, however, causes strong electric field across the thin photoconductive layer with a significant avalanche effect, which induces undesired increase of dark current. Here, in order to overcome this problem, we investigated how photoconductive-layer thickness and passivation-layer conductivity impact on voltage-application-induced bright and dark charge densities. Consequently, suppression of dark charge density with thick photoconductive layer and low-conductive passivation layer is a key factor for optimization of light-addressable electrode. With this designing strategy, we developed a novel light-addressable electrode using titanium dioxide as photoconductor. To suppress avalanche effect, the thickness of the titanium-dioxide layer was designed to be 1.5 μm. The fabricated electrode turned out to have a sufficient photoelectric property; the bright charge density reached up to 70 μC/cm2 and the bright to dark charge density ratio, over 10, which can realize stimulation to cultured dissociated neurons.
  • 小山内 実, 矢口 雄一, 山田 尚宏, 大星 文人, 八木 哲也
    2008 年 128 巻 7 号 p. 1050-1057
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    The striatum plays an important role in linking cortical activity to basal ganglia outputs. We conducted the calcium (Ca2+) imaging to investigate the spontaneous activities of the striatum using acute slice preparations. The corticostriatal slices of rats were stained with Fura-PE3-AM. Long lasting spontaneous intracellular Ca2+ ([Ca2+]i) changes, which lasted up to several hundreds seconds, were observed. The amplitudes and the intervals of the changes were variable even in a single cell. Most cells exhibited irregular frequencies, but some exhibited oscillatory features. Most of these [Ca2+]i changes were not suppressed by TTX, blocker of action potentials. The number of the active cells, which exhibited the [Ca2+]i changes, was greatly reduced by the intracellular Ca2+ store depletor, thapsigargin. Therefore, the intracellular Ca2+ store is likely to contribute to the [Ca2+]i transients.
    The [Ca2+]i changes under standard ACSF and TTX showed different levels of regularity. We tested synchronization of the [Ca2+]i changes between cell pairs under the both conditions. The number of synchronized cell pairs reduced in TTX. These results suggested that TTX insensitive and slow rate [Ca2+]i changes might exert the information processing in the striatum.
  • —コントラストと可読性の関係—
    齋藤 大輔, 斎藤 恵一, 斎藤 正男
    2008 年 128 巻 7 号 p. 1058-1063
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Web page legibility is important because of WWW dissemination and color combinations between a foreground and a background are the crucial factors to provide sufficient legibility. In our previous studies, the visibilities of several web-safe color combinations were examined using a psychological method. In those studies, simple stimuli were used because of experimental restriction. In this study, legibility of sentences on Web sites was examined using a psychophisiological method by oculomotor and the effect of the achromatic color combinations, that is contrast, was examined with calculated reading time. The presentation stimuli were positive coloration whose font color luminance is lower than background color, and negative coloration whose font color luminance is higher than background color. And the number of characters per line in each page was arranged in the same number, and the four achromatic colors that is, the contrast between the background color and font color are 92.5, 75.0, 50.0 and 25.0 percent, were examined. As the results, it was shown that reading time of became long when the contrast. However, in the negative coloration, there were great differences between individuals. Therefore, considering web accessibility, the legibility is found to be useful for using a positive coloration.
  • 武内 彬正, 小川 肇, 森口 裕之, 李 鍾国, 野城 真理, 小谷 潔, 神保 泰彦
    2008 年 128 巻 7 号 p. 1064-1069
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    To understand the detailed mechanisms of arrhythmia and its treatment methods, it is required to elucidate the mechanisms of formation and debacle of cardiac beat at a microscopic level by using appropriate in vitro models of cardiac beating. In this study, we have developed a method for an medium-exchange-free culture of rat cardiac myocytes, and carried out long-term recording of electrical activity of cardiac myocytes from postnatal rat by means of microelectrode-array (MEA) and the new culture method. Figure 6 a) ∼ f) is a series of the properties of spontaneous beating (mean beating interval, standard deviation and coefficient of variation) of cardiac myocytes cultured by conventional culture method with alternate-day medium exchange (a ∼ c) or newly developed “molecular diffusion culture” method (d ∼ f). As shown in these figures, the difference of the beating property between the individual cultures, which is observed in conventional cultures (a) ∼ c)), was dramatically reduced in the molecular diffusion cultures (d) ∼ f)). In addition, these results also indicated that there is a transient period when all of mean beating interval, standard deviation, and coefficient of variation increase transiently before the formation of stable rhythmic fast beat.
<通信・ネットワーク>
  • 作田 俊一, 樋熊 利康, 徳田 正満
    2008 年 128 巻 7 号 p. 1070-1080
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    In this paper, we calculated balance-unbalance conversion factor, common mode current and leaked electric field in the power line with branch in high frequency by using the method of moments. A power line in general domestic has diverged variously. Especially, we paid attention to the lamp switch branch, in which only one line of the pair line is lengthened to make an ON/OFF switch. Furthermore, in order to improve the calculation accuracy, we measured lamp switch equivalent circuit for MHz band by the impedance analyzer. In order to confirm the validity of the calculation, we measured these characteristics of the same model beforehand, and compared the measurement value with the calculation value. As the result, the calculation and measurement values are approximated well in these characteristics. And the characteristics of power line with lamp switch branch in the condition of switch on and off are cleared up by these calculation and measurement.
  • 古賀 久雄, 児玉 宣貴
    2008 年 128 巻 7 号 p. 1081-1086
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Recently, the demand of high speed network in home is increasing. Some Multicarrier Modulation (MCM) based systems use FFT OFDM, and some use a Wavelet OFDM in place of FFT OFDM. Wavelet transforms consist of an M-band transmultiplexers, which use filters of greater length than the rectangular windows used in FFT OFDM. The use of symbols of longer duration allows obtaining lower side-lobe levels with respect to FFT OFDM. Better stop-band attenuation results in both lower levels of inter-carrier interference (ICI) and greater robustness to narrowband interference. For the power line channel, we have chosen two channels measured by network analyzer. The root mean square (R.M.S.) delay spreads of Channels A and B are 0.22 [μsec] and 1.1 [μsec], respectively. In this paper, the PHY (Physical layer) data rates [Mbps] achievable by Wavelet OFDM over Channels A and B are shown for two different kinds of FEC. Then, the effects of ISI and ICI on Wavelet OFDM can be compensated by increasing the number of carriers. Finally, it is shown that Wavelet OFDM characteristic is better than that of FFT OFDM about PHY rates [Mbps] with the same channels.
<音声画像処理・認識>
  • 茂出木 敏雄
    2008 年 128 巻 7 号 p. 1087-1095
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    We are developing audio watermarking techniques which enable extraction of embedded data by cell phones. For that we have to embed data onto frequency ranges, where our auditory response is prominent, therefore data embedding will cause much auditory noises. Previously we have proposed applying a two-channel stereo play-back feature, where noises generated by a data embedded left-channel signal will be reduced by the other right-channel signal. However, this proposal has practical problems of restricting extracting terminal location. In this paper, we propose synthesizing the noise reducing right-channel signal with the left-signal and reduces noises completely by generating an auditory stream segregation phenomenon to users. This newly proposed makes the noise reducing right-channel signal unnecessary and supports monaural play-back operations. Moreover, we propose a wide-band embedding method causing dual auditory stream segregation phenomena, which enables data embedding on whole public phone frequency ranges and stable extractions with 3-G mobile phones. From these proposals, extraction precisions become higher than those by the previously proposed method whereas the quality damages of embedded signals become smaller. In this paper we present an abstract of our newly proposed method and experimental results comparing with those by the previously proposed method.
  • 寒澤 佑介, 小林 宏樹, 大川 剛直, 伊東 敏夫
    2008 年 128 巻 7 号 p. 1096-1101
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Developing on-board automotive driver assistance systems aiming to alert drivers about driving environments, and possible collision with other vehicles has attracted a lot of attention lately. Especially, many researchers have suggested the forward vehicle recognition technology by a camera on vehicle. In the forward vehicle recognition, however, it is difficult to detect the features of vehicle from a distant vehicle image by conventional methods because the image is too low-resolution (LR). This paper presents vehicle image recognition technology for detecting of the features of a distant vehicle by frame-composition of moving images. To detect the vehicle features of a distant LR vehicle image, we use the moving images obtained from the camera on the vehicle, and utilize super-resolution (SR) image reconstruction. SR image reconstruction is to use signal processing techniques to obtain a high-resolution (or sequence) image from observed multiple LR images. Use of this technique on real road image, we show the effectiveness of the proposed techniques.
<制御・計測>
  • 小林 康秀, 塩谷 弦, 疋田 真一, 野村 和也
    2008 年 128 巻 7 号 p. 1102-1109
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Wiener systems which consist of a dynamic linear block followed by a static nonlinear element have been used in numerous applications. In many cases, the system parameters are affected by changes in the environmental conditions. This paper describes a new approach to the on-line identification of time-varying Wiener systems. The time-varying linear parameters and the static nonlinear characteristics are estimated by the neural networks which can represent various nonlinear characteristics. The initial states of the linear model in each estimation window are not available in the Wiener systems. Thus, the initial states and the other system parameters are estimated simultaneously by the nonlinear optimization techniques. Furthermore, the optimal numbers of hidden units in the neural networks are determined by the minimum description length (MDL) criterion.
    As the result of the simulation of this method, more accurate parameters can be obtained than the result without the estimation of initial states and MDL.
  • 川村 雄, 平田 健太郎, 鈴木 新, 杉本 謙二
    2008 年 128 巻 7 号 p. 1110-1116
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    In this paper, a model-based temperature control method for cooking appliances is proposed. Due to structural and sanitary limitations, no sensor for the temperature of the cooking object is equipped in general. After constructing a state space model for the heating process and identifying the model parameters for each distinct volume of the cooking object, a state observer is designed. By using this observer as a softsensor, feedback temperature control is implemented instead of the conventional model-less on-off pattern control. Its high tracking performance is demonstrated via numerical examples and experiments.
  • 上保 徹志, 中迫 昇, 大亦 紀光, 板垣 英恵
    2008 年 128 巻 7 号 p. 1117-1122
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    In many engineering fields, distance to target is fundamental and very important information. Acoustical signal, such as audible sound or ultrasonic, often plays an essential role in measurement of distance. To measure distance, the time delay of reflected wave measured with reference to transmitted pulse wave, i.e. time-of-flight (TOF) is used typically. This method, however, can not measure short distance because the transmitted wave, which has not attenuated enough as of reception of reflected waves, suppresses the reflected waves for short distance. Meanwhile, in the research field of microwave radar, to measure distances to multiple targets even if short, a novel method by using standing wave has been recently proposed. We apply the fundamental principle of this method to estimation of short distance for multiple targets using audible sound. In this paper, we focus our attention on audible band-limited noise. To verify the validity and effectiveness of our method, we perform computer simulations and experiments. As a result, it has been confirmed that short distances to multiple targets, such as the distances to two targets located at 0.1m and 1m, can be estimated properly by our method.
<ロボティクス>
  • 山田 孝文, 山口 智
    2008 年 128 巻 7 号 p. 1123-1130
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    In this paper, for agents working on POMDP, a learning algorithm combining the memory-less learning and the memory-based learning is proposed. At first stage of the propposed algorithm, memory-less learning is applied. As a memory-less learning algorithm, the stochastic gradient method is employed. While the first stage, a state-action set series that accmplish the task is stored in memory. In the second stage, the memory-based learning is applied. In this process, only the series that obtained the first stage is used, so that this method is able to reduce the number of required memory effectively.
    The proposed algorithm are applied three kinds of simulation to be compared with memory-less learning algorithm. Through the computer simulations, it shown that the proposed algorithms works effectively in POMDP than ordinary memory-less learnings.
<ソフトコンピューティング>
  • 豊田 丈輔
    2008 年 128 巻 7 号 p. 1131-1136
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    So far, there are many researches on Bin Packing Problem (BPP). Cutting Stock Problem for timber precutting (CSP) is one of the kind of BPP. There are some solving methods such as Integer Programming method, First Fit method and Best Fit method as for this. There are a few papers in which Genetic Algorithm (GA) is applied to BPP. This is because building model is difficult and generating effective individuals of next generation by crossover is also difficult. In this paper, an application of GA to CSP is examined. CSP contains mother materials consisted by plural lengths, which is different from general BPP. Therefore we devise doubled structure of gene. Reflecting dynamic change to crossover operation based on the result of combination, new model is built. Convergence process is improved largely by this newly proposed method.
  • 山本 健二, 小圷 成一, 岡本 卓, 平田 廣則
    2008 年 128 巻 7 号 p. 1137-1142
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Neural Networks (NN) are widely applied to information processing because of its nonlinear processing capability. Digital hardware implementation of NN seems to be effective in construction of NN systems in which real-time operation and much further wide applications are possible. However, the digital hardware implementation of analogue NN is very difficult because we have to fulfill the restrictions about circuit resource, such as circuit scale, arrangement, and wiring. A technique that uses pulsed neuron model instead of analogue neuron model as a method of solving this problem has been proposed, and its effectiveness has been confirmed. To construct Pulsed Neural Networks (PNN), Back Propagation (BP) learning has been proposed. However, BP learning takes much time to construct PNN compared with the learning of analogue NN. Therefore some method to speed up BP learning of PNN is necessary. In this paper, we propose a fast BP learning using optimization of learning rate for PNN. In the proposed method, the learning rate is optimized so as to speed up the learning at every learning epoch. To evaluate the proposed method, we apply it to some pattern recognition problems, such as XOR, 3-bits parity, and digit recognition. Results of computational experiments indicate the validity of the proposed method.
  • 平岡 創土, 岡本 卓, 相吉 英太郎
    2008 年 128 巻 7 号 p. 1143-1153
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Particle Swarm Optimization (PSO), which has attracted a great deal of attention as a global optimization method in recent years, has a drawback in that its continuous search based on its excellent dynamic characteristics can not be executed stably until the end of computation due to its much strong convergence trend. In this paper, we propose “Repetitive Search Guideline” which differs from a common guideline in the improved methods which have ever been proposed and by which the continuous search of PSO is achieved without lack of PSO's excellent dynamic characteristics due to the repetitive search in a promise area where objective function value is expected to be small. We consider four improved methods based on the proposed guideline, and then, their effectiveness are confirmed through applications to 100 variables multi-peaked benchmark problems.
  • 杉浦 孔明, 川上 浩司, 片井 修
    2008 年 128 巻 7 号 p. 1154-1161
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    This paper proposes a method that automatically designs the sensory morphology of a mobile robot. The proposed method employs two types of adaptations -ontogenetic and phylogenetic- to optimize the sensory morphology of the robot. In ontogenetic adaptation, reinforcement learning searches for the optimal policy which is highly dependent on the sensory morphology. In phylogenetic adaptation, a genetic algorithm is used to select morphologies with which the robot can learn tasks faster. Our proposed method is applied to the design of the sensory morphology of a line-following robot. We carried out simulation experiments to compare the design solution with a hand-coded robot. The results of the experiments revealed that our robot outperforms a hand-coded robot in terms of the line-following accuracy and learning speed, although our robot has fewer sensors than the hand-coded one. We also manufactured a physical robot using the design solution. The experimental results revealed that this physical robot uses its morphology effectively and outperforms the hand-coded robot.
<システム>
  • 中野 真一, 石亀 篤司, 安田 恵一郎
    2008 年 128 巻 7 号 p. 1162-1167
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    This paper presents a new Particle Swarm Optimization based on the concept of Tabu Search. In PSO, when a particle finds a local optimal solution, all of the particles gather around the one, and cannot escape from it. On the other hand, TS can escape from the local optimal solution by moving away from the best solution at the present. The proposed Tabu List PSO (TL-PSO) is the method for combining the excellence of both PSO and TS. In this method, it stores the history of pbest in Tabu List. When a particle has a reduced searching ability, it selects a pbest of the past from the history of them, and it is applied to update. This makes each particle active, and the searching ability of swarm makes progress. Then, the proposed method is validated through numerical simulations with several functions which are well known as optimization benchmark problems comparing to the conventional PSO methods.
<ソフトウェア・情報処理>
  • 中辻 秀人, 大松 繁
    2008 年 128 巻 7 号 p. 1168-1175
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    In recent years, the wavelet transform on the basis of multiresolution analysis has been considered as a concrete algorithm of an integral wavelet transform which performs a spectral analysis in time-frequency domain. On the other hand, authors have proposed a new analyzing method which updates the spectrum by using an input data only. The new method proposes analysis approach 1(AA1) which is a fundamental analysis method, and analysis approach 2(AA2) which is an analysis method that achieves high-speed processing. Decomposition and reconstruction of a signal based on AA1 was already proposed by the authors. This paper shows decomposition and reconstruction of a signal based on AA2. The decomposition wave in AA2 can not be obtained by the sama method as in the case of AA1 but by a mathematical processing. By the processing, the decomposition wave in AA2 is identical to the decomposition wave in AA1. Therefore, the decomposition and the reconstruction of the signal in AA2 result in the decomposition and the reconstruction of the signal in AA1. As an example of a numerical analysis, we show decomposition and reconstruction of Japanease vocal sound /i/.
  • 藤澤 正一郎, 黒住 亮太, 三谷 誠二, 末田 統
    2008 年 128 巻 7 号 p. 1176-1182
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    In Japan, it is reported about 90% of the persons with visual impairment are the persons with low visual capability. However, the database of the low visual capability and the standard about the easily comprehensible visual information presentation are not existed yet. Therefore, the categories of colour similarity of the persons with low visual capability are measured. However, measuring various colour combinations is placing a burden on the object person. Therefore, in this research, development of the categories of colour similarity estimation algorithm is proposed. Applying the generalization capability of the artificial neural network, the distribution of the categories of colour similarity will be obtained from the limited colour combination measures.
特集研究開発レター
<医用電子・生体工学>
論文
<電子・集積回路>
  • 藤本 邦昭, 佐々木 博文, 矢原 充敏
    2008 年 128 巻 7 号 p. 1185-1190
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    In this paper, we propose the dividing ratio changeable digital phase locked loop (PLL) based on phase state memory and double clock-edge detection in which satisfies three characteristics of a low jitter, wide lock-in range, and fast pull-in at the same time. The counter for the double edge detection of the base clock reduces the circuit scale by using the selector. In a steady state, the output jitter of the proposed digital PLL becomes always half pulse width of the base clock regardless of the frequency fluctuation of the base clock. Also, the upper bound frequency of the lock-in range becomes 6 times that of the conventional dividing ratio changeable digital PLL, when the permissible output jitter is identical. Furthermore, the fast pull-in is finishes in one period of the input signal and the pulse width of the multiplication output signal becomes almost constant.
<センシング>
  • 福地 哲生, 二宮 英樹
    2008 年 128 巻 7 号 p. 1191-1196
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    An experimental study was performed to evaluate the applicability of anti-Stokes Raman scattering to leak detection of hydrogen gas. The laser beam of wavelength 355 nm and Stokes beam of wavelength 416 nm were aligned in a collinear configuration, and hydrogen gas was released into air through a nozzle of aperture 1 mm placed immediately below the beam path. The anti-Stokes beam of wavelength 309 nm was generated by coherent anti-Stokes Raman scattering. The three beams were incident on a diffusing plate, and the anti-Stokes beam was selectively imaged using an image intensifier and two interference filters. The interference filters provided sufficient rejection at 355 nm, 416 nm, and at fluorescence wavelengths to provide a clear image at 309 nm. The anti-Stokes beam could be imaged down to hydrogen gas release rates of 2 ml/min when the nozzle exit was 0.5 mm below the laser beam and Stokes beam. The anti-Stokes beam could be imaged for separation distance (between the laser and Stokes beams and the nozzle exit) of <3.5 mm, for a gas release rate of 10 ml/min.
<通信・ネットワーク>
  • Nikolay V. Korovkin, Elena B. Solovyeva, Masashi Hayakawa
    2008 年 128 巻 7 号 p. 1197-1203
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    The effect of two disturbing sources with close frequencies on a nonlinear circuit is investigated, because it is shown that low-frequency oscillations occur frequently in such a circuit. These low-frequency oscillations represent a significant threat to the electronic equipment, since standard filters do not suppress such low-frequency harmonics. As the source of low-frequency disturbance is the nonlinearity of the electronic system characteristic, the disturbance compensation is possible by means of linearization of this characteristic. Linearization of the characteristic is suggested to be carried out by synthesis of cascade connection of the initial electronic system and a compensation circuit. The electronic system nonlinear operator is represented in the form of Volterra polynomial, and the operator of the compensation circuit is designed so as to exclude nonlinear functionals from Volterra polynomial. As a result, the resultant circuit (cascade connection of the electronic system and the compensation circuit) is presented by a linear operator. Presented results of compensation of the detector nonlinear transformations illustrate the efficiency of the suggested method for the suppression of low-frequency disturbances.
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  • 西野 聰, 大嶋 建次
    2008 年 128 巻 7 号 p. 1204-1211
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Male and female recognition is necessary to make security stronger and when various statistics on the visitor are taken in commercial facilities and so on. The conventional method of male and female recognition is currently determined by using the person's appearance, the person's dress and in such cases, the way of walking, the foot pressure, the hair type. But, these characteristics can be intentionally changed by human intervention or design. The proposed method gets a difference in the male's and female's characteristics by taking absorbance characteristic of the fat distribution of the person's cheek by near infrared ray scanning spectrophotometer. This is a male and female recognition based on the new concept idea which this is used for. Consequently, this can be used to recognize a male from a female even if a male turns himself into the female intentionally (and vice versa), because this method involves biometrics authentication.
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  • 坪根 正, 栗本 健一, 杉山 晃一, 和田 安弘
    2008 年 128 巻 7 号 p. 1222-1230
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    Reinforced learning by which a robot acquires control rules through trial and error has gotten a lot of attention. However, it is quite difficult for robots to acquire control rules by reinforcement learning in real space because many learning trials are needed to achieve the control rules; the robot itself may lose control, or there may be safety problems with the control objects. In this paper, we propose a method in which a robot in real space learns a virtual task; then the task is transferred from virtual to real space. The robot eventually acquires the task in a real environment. We show that a real robot can acquire a task in virtual space with an input device by an example of an inverted pendulum. Next, we verify availability that the acquired task in virtual space can be applied to a real world task. We emphasize the utilization of virtual space to effectively obtain the real world task.
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  • 林 章浩, 片岡 信弘
    2008 年 128 巻 7 号 p. 1231-1241
    発行日: 2008/07/01
    公開日: 2008/07/01
    ジャーナル フリー
    With the prevalence of CMMI (Capability Maturity Model Integration) that is developed in the United States and the international standardization model of Software Process Assessment ISO/IEC 15504, SPI (Software Process Improvement) based on Software Process Assessment is gaining ground in Japan as well. One of the objectives in SPI is to prevent the occurrence of errors in the downstream process by thorough process management in the upstream process. In order to implement the SPI from such viewpoints, this paper suggests the method to analyze Problem Reports developed in the testing process of a project, to specify software bugs existent in leading processes and to identify the SPI in the upstream process. By means of Problem Reports that is capable of externalization and is used in testing processes, knowledge that has not been externalized will be specified as Defect Cluster. Furthermore, deliverables in each process will be identified from the properties of Defect Cluster to implement the SPI, which is of the essence, by identifying processes causing trouble. In the project that was the analytical target, there were 608 Problem Reports in its testing process. As a result of the analysis, it was found that by identifying processes in the upper process to improve with the techniques recommended in this paper, about 13% of cases causing trouble could be prevented from occurring, which will contribute to productivity improvement due to a decrease in the number of rework processes.
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