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| 1.
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Mukhopdhyay, S.C. ; Iwahara, Masayoshi ; Yamada, Sotoshi ; 岩原, 正吉 ; 山田, 外史
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For the last few years the authors have been involved in the design and development of different topologies of magnetic current limiter (MCL). The small scale laboratory models have been fabricated and experiments were conducted. The
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simulated performance obtained from the tableau approach based on lumped parameter model shows discrepancy with the experiment. This paper describes the necessity of electromagnetic field computation which clearly shows the discrepancy between the observed and the simulation results, which can be attributed to a non uniform flux distribution in the core.
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| 2.
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Kacprzak, D. ; Yamada, Sotoshi ; Iwahara, Masayoshi ; 山田, 外史 ; 岩原, 正吉
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This paper presents simulated amplitude and phase characteristics obtained during the inspection of printed circuit board by an eddy-current testing probe. The simulation is based on the "two-components" nature of the output signal.
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Amplitude and phase characteristics, obtained during the experimental inspection and simulation, are presented.
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| 3.
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Mukhopadhyay, S.C. ; Iwahara, Masayoshi ; Yamada, Sotoshi ; Dawson, F.P. ; 岩原, 正吉 ; 山田, 外史
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Different topological configurations for a passive magnetic current limiter consisting of a permanent magnet and saturable core are discussed in this paper. The models for a series/parallel biasing mode, and a single/three phase supply
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system have been fabricated and the experiments have been carried out for the performance evaluation. Using tableau method, the transient performance of different models has been simulated. The feasibility of applying the current limiter for the protection of power semiconductor devices in moderately low voltage applications is investigated.
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| 4.
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Miyoshi, Seiji ; Nakayama, Kenji
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In this paper, the geometric learning algorithm (GLA) is proposed for an elementary perceptron which includes a single output neuron. The GLA is a modified version of the affine projection algorithm (APA) for adaptive filters.
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The weights update vector is determined geometrically towards the intersection of the k hyperplanes which are perpendicular to patterns to be classified. k is the order of the GLA. In the case of the APA, the target of the coefficients update is a single point which corresponds to the best identification of the unknown system. On the other hand, in the case of the GLA, the target of the weights update is an area, in which all the given patterns are classified correctly. Thus, their convergence conditions are different. In this paper, the convergence condition of the 1st order GLA for 2 patterns is theoretically derived. The new concept `the angle of the solution area' is introduced. The computer simulation results support that this new concept is a good estimation of the convergence properties.
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| 5.
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Tokui, N. ; Nakayama, Kenji ; Hirano, Akihiro
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In order to achieve fast convergence and less computation for adaptive filters, a joint method combining a whitening process and the NLMS algorithm is a hopeful approach. However, updating the filter coefficients is not synchronized with the
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reflection coefficient updating resulting in unstable behavior. We analyzed effects of this, and proposed the Synchronized Learning Algorithm to solve this problem. Asynchronous error between them is removed, and fast convergence and small residual error were obtained. This algorithm, however, requires O(ML) computations, where M is an adaptive filter length, and L is a lattice predictor length. It is still large compared with the NLMS algorithm. In order to achieve less computation while the fast convergence is maintained, a block implementation method is proposed. The reflection coefficients are updated at some period, and are fixed during this interval. The proposed block implementation can be effectively applied to parallel form adaptive filters, such as sub-band adaptive filters. Simulation using speech signal shows that a learning curve of the proposed block implementation a little slower than the our original algorithm, but can save the computational complexity.
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| 6.
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Nakayama, Kenji ; Hirano, Akihiro ; Nishiwaki, Takayuki
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A network structure and its learning algorithm have been proposed for blind source separation applied to nonlinear mixtures. The network has a cascade form consists of a source separation block and a linearization block in this order.
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The conventional learning algorithm is employed for the separation block. A new learning algorithm is proposed for the linearization block assuming 2nd-order nonlinearity. After, source separation, the outputs include the nonlinear components for the same signal source. This nonlinearity is suppressed through the linearization block. Parameters in this block are iteratively adjusted based on a process of solving a 2nd-order equation of a single variable. Simulation results, using 2-channel speech signals and an instantaneous nonlinear mixing process, show good separation performance.
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| 7.
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Nakayama, Kenji ; Hirano, Akihiro ; Fusakawa, M.
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In multilayer neural networks, network size reduction and fast convergence are important. For this purpose, trainable activation functions and nonlinear synapses have been proposed. When high-order polynomials are used for
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nonlinearity, the number of terms in the polynomial becomes a very large for a high-dimensional input. It causes very complicated networks and slow convergence. In this paper, a method to select the useful terms in the polynomial in a learning process is proposed. This method is based on the genetic algorithm (GA), and combines the internal information, magnitude of connection weihgts, to select the gene in the next generation. A mechanism of pruning the terms is inherently included. Many examples demonstrate usefulness of the proposed method compared with the ordinary GA method. Convergence is stable and the number of the selected terms is well reduced.
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| 8.
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Kobori, Hideki ; Ikeda, Kazushi ; Nakayama, Kenji
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金沢大学理工研究域電子情報学系<br />A model of dynamic associative memories is proposed in this paper. The aim is to find all stored pa
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tterns, and to distinguish the stored and the spurious patterns. Aihara used chaotic neurons and showed that his model has a nonperiodic associative dynamics. In his model, however, it is difficult to distinguish the stored patterns from the others, because the state of the network changes continually. We propose such a new model of neurons that each neuron changes its output to the other when the accumulation of its internal state exceeds a certain threshold. By computer experiments, we show that the state of the network stays at the stored pattern for a while and then travels around to another pattern, and so on. Furthermore, when the number of the stored patterns is small, the stored and the spurious patterns can be distinguished using interval of the network staying these patterns.
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| 9.
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Senda, Kei ; Matsumoto, Tsutomu ; Okano, Yuzo
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金沢大学工学部<br />泉田, 啓<br />This paper addresses an experimental system simulating a free-flying space robot, which has been
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constructed to study autonomous space robots. The experimental system consists of a space robot model, a frictionless table system, a computer system, and a vision sensor system. The robot model is composed of two manipulators and a satellite vehicle, and can move freely on a two-dimensional planar table, without friction, using air-bearings. The robot model has successfully performed the automatic truss structure assembly, including many jobs, e.g., manipulator berthing, component manipulation, arm trajectory control collision avoidance, assembly using force control, etc. Moreover, even if the robot fails in a task planned in advance, the robot re-plans the task by using reinforcement learning, and obtains the task goal for basically kinematic problems. But, for a class of complicated dynamic problems, the computational periods and efforts are infeasible for on-line learning. Some approaches are proposed to accelerate the learning speed, which also give models of cognitive actions and approaches to so-called a frame problem. The experiment demonstrates the possibility of the autonomous construction and the usefulness of space robots.
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| 10.
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Khalaf, Ashraf A.M. ; Nakayama, Kenji
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Time series prediction is a very important technology in a wide variety of field. The actual time series contains both linear and nonlinear properties. The amplitude of the time series to be predicted is usually continuous value. For
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this reason, we combine nonlinear and linear predictors in a cascade form. In order to estimate the minimum size of the proposed predictor, we propose a nonlinearity analysis for the time series of interest. Computer simulations using the sunspot data have demonstrated the efficiency of the proposed predictor and the nonlinearity analysis.
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11. Phase-shift algorithm for white-light interferometry insensitive to linear errors in phase shift
Adachi, Masaaki
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金沢大学理工研究域機械工学系<br />White-light interference has changes in fringe contrast. When phase-shift techniques are applied to
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white-light interference, the phase-shift algorithm which can extract the phase accurately under the contrast changes is required. There is often another requirement that the phase shift between frames should not be restricted to π/2. Computer simulations show that the well-known algorithms have non-negligible errors under both requirements. To find an algorithm which will satisfy the requirements, I extract individual terms (I j ∓ I k ) in an algorithmic equation by considering symmetry of light intensity against phase, where I j is light intensity just after the j-th phase shift. Using computer simulations, I search for appropriate coefficients by which the terms are multiplied in the equation, finally finding an algorithm which satisfies both the requirements with the phase shift used. © 2008 The Optical Society of Japan.
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| 12.
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Iwai, Yoshio ; Higashi, Hidenori ; Uchida, Hirohisa ; Arai, Yasuhiko
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金沢大学大学院自然科学研究科生産プロセス<br />NVT ensemble molecular dynamics simulation has been applied to calculate the diffusion coeffic
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ients of naphthalene and 2-naphthol in supercritical carbon dioxide in the pressure range from 8 to 40 MPa under infinite dilution conditions. The Lennard-Jones (12-6) potential function was used as the intermolecular potential. The calculation results showed good agreement with the experimental values, by using the intermolecular interaction parameters between unlike molecules which were determined by Monte Carlo simulation to give good representation for the solubilities of naphthalene and 2-naphthol in supercritical carbon dioxide.
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| 13.
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Wang, Youhua ; Ikeda, Kazushi ; Nakayama, Kenji
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金沢大学大学院自然科学研究科情報システム<br />金沢大学工学部<br />The numerical property of an adaptive filter algorithm is the most important prob
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lem in practical applications. Most fast adaptive filter algorithms have the numerical instability problem and the fast Newton transversal filter (FNTF) algorithms are no exception. In this paper, we propose a numerically stable fast Newton type adaptive filter algorithm. Two problems are dealt with in the paper. First, we derive the proposed algorithm from the order-update fast least squares (FLS) algorithm. This derivation is direct and simple to understand. Second, we give the stability analysis using a linear time-variant state-space method. The transition matrix of the proposed algorithm is given. The eigenvalues of the ensemble average of the transition matrix are shown to be asymptotically all less than unity. This results in a much improved numerical performance compared with the FNTF algorithms. The computer simulations implemented by using a finite-precision arithmetic have confirmed the validity of our analysis.
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| 14.
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Hara, Kazuyuki ; Nakayama, Kenji
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A training data selection method for multi-class data is proposed. This method can be used for multilayer neural networks (MLNN). The MLNN can be applied to pattern classification, signal process, and other problems that can be
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considered as the classification problem. The proposed data selection algorithm selects the important data to achieve a good classification performance. However, the training using the selected data converges slowly, so we also propose an acceleration method. The proposed training method adds the randomly selected data to the boundary data. The validity of the proposed methods is confirmed through the computer simulation.
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| 15.
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Yuhi, Masatoshi ; Chiang, Mei
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金沢大学大学院自然科学研究科<br />We investigate the slow spreading of fluid mud over a gently sloped conical surface which may simula
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te a shallow basin or a hill. The mud is assumed to behave as a Bingham plastic possessing a finite yield stress and the lubrication approximation is used. Because of the finite yield stress, a variety of non-trivial equilibrium profiles can exist, corresponding to the state of deposit at the end of upward or downward motion. Analytical solutions are derived for axially symmetric deposits. It is shown that the front of the final profile in axisymmetric spreading is of a common form in dimensionless variables, independent of the total mud volume. Transient evolutions are then studied numerically by employing a finite-volume scheme for both axially symmetric and asymmetric spreading from a localized source. The characteristic features of the mud pile at different stages of spreading are examined. The final shape in asymmetric spreading is strongly affected by the total volume released and by the rate of discharge.
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| 16.
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Nishiwaki, Takayuki ; Nakayama, Kenji ; Hirano, Akihiro
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A network structure and its learning algorithm have been proposed for blind source separation applied to nonlinear mixtures. Nonlinearity is expressed by low-order polynomials, which are acceptable in many practical applications. A
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separation block and a linearization block are cascaded. In the separation block, the cross terms are suppressed, and the signal sources are separated in each group, which include its high-order components. The high-order components are further suppressed through the linearization block. A learning algorithm minimizing the mutual information is applied to the separation block. A new learning algorithm is proposed for the linearization block. Simulation results, using 2-channel speech signals, instantaneous mixtures, and 2nd-order post nonlinear functions, show good separation performance.
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| 17.
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Nakayama, Kenji ; Hirano, Akihiro ; Kourin, Makoto
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In this paper, a synthesis and learning method for the neural network with embedded gate units and a multi-dimensional input is proposed. When the input is multi-dimensional, gate functions are controlled in a multi-dimensional space.
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In this case, a hypersurface, on which the gate function is formed should be optimized. Furthermore, the switching points should be considered on the unit input. An initialization and a control methods for gate functions, which optimize the hypersurface, the switching point and the inclination, are proposed. The stabilization methods, already proposed, are further modified to be applied to the multi-dimensional environment. The gate functions can be trained together with the connection weights. Discontinuous function approximation is demonstrated to confirm usefulness of the proposed method.
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| 18.
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犀川, 太 ; Saikawa, Yutaka
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金沢大学医学部附属病院<br />1.平成17年度の研究期間では,セルラオートマトン法を用いて顆粒球系造血モデルの骨格を構築した。幹細胞から成熟好中球までの造血過程を分裂期細胞と非分裂期細胞に大別し、分化段階に応じて15段階に分画化した。実
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験的に得られている分裂回数および通過時間(分化に要する時間)に対応した計算ステップ数をそれぞれの分化段階に設定した。その特徴は,1)骨髄を想定した3次元空間に、2)生体の骨髄に存在する骨梁や血管を構造物として取り入れた近似的骨髄空間を構築した。3)細胞は局所近傍則に従って解析空間内の区分領域から隣接する区分領域へ移動し、分化・分裂する。4)細胞の動態を直接モニター上に表示し,5)解析空間内の全ての細胞の位置、分化段階は経時的に抽出可能とした。この造血モデル上で造血システムの恒常性維持、抗がん剤投与、およびG-CSF投与時の顆粒球造血過程の細胞動態を解析し、臨床データとの比較からモデルの有用性を示すことが可能であった。2.平成18年度の研究期間では,1)上記解析結果の学会報告.2)シュミレーションソフト化,3)微小残存白血病細胞(MRD)の動態解析を行った.【結果】1)学会発表:顆粒球系造血シュミレーションモデルを用いて造血システムの恒常性維持、抗がん剤投与、およびG-CSF投与時の顆粒球造血過程の細胞動態を臨床データと比較し,モデルの有用性を第4回International conference on computational methods in systems biology,in Trento, Italy, October18-19,2006で発表(演題:Granulopoiesis in Computational Haematology,ポスター発表)した.2)条件設定やデータの入力を簡易化することは,使いやすさの向上と解析時間の短縮を図ることが出来る.また,造血の基本理解を目指した教育ソフトとしての普及版を作成するためには汎用化(Windows/Mac対応)が必要と考え,まずはユーザーフレンドリー仕様のWindows対応版の開発を進めている.3)白血病幹細胞の存在が概念から事実的存在へと明らかになりつつある.微小残存白血病細胞(MRD)の動態を解析するために,白血病幹細胞をモデルへ導入し,正常幹細胞の動態との比較を開始した.MRDの骨髄細胞の正常分化への影響を動態解析から探り,臨床応用可能な再発予知因子を解明する.<br />In 2005, we attempted to develop a unique computational model of human granulopoiesis to identify the regulatory mechanisms for homeostatic hematopoiesis. A computational approach with mathematical-modeling of the hematopoietic system has been applied for exploring the principles that underlie the system. Models are required of easy access and highly expected to integrate details and reproduce the dynamic behaviors of the cells but also to predict the specific cellular behaviors in response to various simulations. We have successfully developed a new lateral computational modeling for human granulopoiesis using three-dimensional Cellular Automata (3D-CA), which incorporates a spatio-temporal concept to describe the granulopoietic process developing in the finite space of bone marrow cavity. We emphasize unique properties of this model as following ; 1)the model does not contain either governing equations or negative feedback loops assumed for regulation and 2)one can directly view this in silico granulopoiesis on the computer screen, in which HSCs replicate, differentiate, and distribute their offspring in an analytical space consisting of 130 x 130 x 130 unit cubic areas with structural objects assuming vessels and trabecular bones. The model reified the principle that local interaction of individual granulopoietic cells produced feedback circuits leading global dynamics and stability of the system.In 2006, we further applied this model to analyze cellular dynamics of granulopoiesis under chemotherapy and hematopoietic stem cell transplantation. Simulation studies predicted efficacy and minimal requirement of G-CSF scheduling for drug-induced neutropenia. Cellular dynamics of homing HSCs explained difference of engraftment periods observed in different utilization of stem cell sources in transplantation. Learning cellular behaviors from computational hematology could provide the novel strategies for the treatment of hematological malignancies.<br />研究課題/領域番号:17591073, 研究期間(年度):2005 – 2006<br />出典：「3次元モデルを用いた微少残存白血病細胞の動態解析に基づく再発予知的治療戦略の創成」研究成果報告書 課題番号17591073（KAKEN：科学研究費助成事業データベース（国立情報学研究所））（https://kaken.nii.ac.jp/ja/report/KAKENHI-PROJECT-17591073/175910732006kenkyu_seika_hokoku_gaiyo/)を加工して作成
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