Showing papers by "University of Electro-Communications published in 2003"
TL;DR: To take full advantage of a fuzzy Lyapunov function, a new parallel distributed compensation (PDC) scheme is proposed that feedbacks the time derivatives of premise membership functions.
Abstract: This paper addresses stability analysis and stabilization for Takagi-Sugeno fuzzy systems via a so-called fuzzy Lyapunov function which is a multiple Lyapunov function. The fuzzy Lyapunov function is defined by fuzzily blending quadratic Lyapunov functions. Based on the fuzzy Lyapunov function approach, we give stability conditions for open-loop fuzzy systems and stabilization conditions for closed-loop fuzzy systems. To take full advantage of a fuzzy Lyapunov function, we propose a new parallel distributed compensation (PDC) scheme that feedbacks the time derivatives of premise membership functions. The new PDC contains the ordinary PDC as a special case. A design example illustrates the utility of the fuzzy Lyapunov function approach and the new PDC stabilization method.
923 citations
TL;DR: The trade-off problem between the stability and the energy consumption in determining the cyclic period of walking on irregular terrain is pointed out, and one example is shown to solve this problem.
Abstract: We have been trying to induce a quadruped robot to walk with medium walking speed on irregular terrain based on biological concepts. We propose the necessary conditions for stable dynamic walking on irregular terrain in general, and we design the mechanical system and the neural system by comparing biological concepts with those necessary conditions described in physical terms. A PD controller at the joints can construct the virtual spring-damper system as the visco-elasticity model of a muscle. The neural system model consists of a central pattern generator (CPG) and reflexes. A CPG receives sensory input and changes the period of its own active phase. The desired angle and P-gain of each joint in the virtual spring-damper system is switched based on the phase signal of the CPG. CPGs, the motion of the virtual spring-damper system of each leg and the rolling motion of the body are mutually entrained through the rolling motion feedback to CPGs, and can generate adaptive walking. We report on our experimen...
665 citations
TL;DR: A capacity formula as well as a characterization of the strong converse property is given just in parallel with the corresponding classical results of Verdu-Han (1994) which are based on the so-called information-spectrum method.
Abstract: The capacity of a classical-quantum channel (or, in other words, the classical capacity of a quantum channel) is considered in the most general setting, where no structural assumptions such as the stationary memoryless property are made on a channel. A capacity formula as well as a characterization of the strong converse property is given just in parallel with the corresponding classical results of Verdu-Han (1994) which are based on the so-called information-spectrum method. The general results are applied to the stationary memoryless case with or without cost constraint on inputs, whereby a deep relation between the channel coding theory and the hypothesis testing for two quantum states is elucidated.
398 citations
TL;DR: It is found that various membrane proteins anchored to the dense membrane skeleton function as rows of pickets, which even stop the overall diffusion of phospholipids, and may represent a universal mechanism for formation of diffusion barriers in the cell membrane.
Abstract: The formation and maintenance of polarized distributions of membrane proteins in the cell membrane are key to the function of polarized cells In polarized neurons, various membrane proteins are localized to the somatodendritic domain or the axon Neurons control polarized delivery of membrane proteins to each domain, and in addition, they must also block diffusional mixing of proteins between these domains However, the presence of a diffusion barrier in the cell membrane of the axonal initial segment (IS), which separates these two domains, has been controversial: it is difficult to conceive barrier mechanisms by which an even diffusion of phospholipids could be blocked Here, by observing the dynamics of individual phospholipid molecules in the plasma membrane of developing hippocampal neurons in culture, we found that their diffusion was blocked in the IS membrane We also found that the diffusion barrier is formed in neurons 7-10 days after birth through the accumulation of various transmembrane proteins that are anchored to the dense actin-based membrane skeleton meshes being formed under the IS membrane We conclude that various membrane proteins anchored to the dense membrane skeleton function as rows of pickets, which even stop the overall diffusion of phospholipids, and may represent a universal mechanism for formation of diffusion barriers in the cell membrane
345 citations
TL;DR: In this paper, the optical absorption spectra of graphite and carbon nanotubes are calculated for a single-wall carbon nanophase and the chirality dependence of the absorption matrix element is analyzed analytically.
Abstract: The optical absorption spectra of \ensuremath{\pi} electrons are calculated for graphite and carbon nanotubes. Particular attention is paid to the processes contributing to the optical absorption as a function of the electron wave vector k and light polarization direction. The optical absorption amplitude around the K point in the Brillouin zone has a node in the two-dimensional Brillouin zone of graphite. The formula for the absorption scattering matrix around the K point is given analytically by expanding the matrix element into a Taylor series. The chirality dependence of the absorption matrix element of a single-wall carbon nanotube is presented.
253 citations
TL;DR: In this article, the initial grain size effect on submicrocrystalline structure evolution was studied in multiple compressions of a 304 stainless steel at 873 K (0.5Tm).
208 citations
TL;DR: In this paper, the structure and properties of bismuth nanowires and carbon nanotubes are discussed and compared with those of carbon nanostructures and nanoscience concepts.
207 citations
TL;DR: It is demonstrated by computational experiments on random graphs with up to 15,000 vertices and on DIMACS benchmark graphs that the algorithm remarkably outperforms other existing algorithms in general.
Abstract: We present an exact and efficient branch-and-bound algorithm for finding a maximum clique in an arbitrary graph. The algorithm is not specialized for any particular kind of graph. It employs approximate coloring and appropriate sorting of vertices to get an upper bound on the size of a maximum clique. We demonstrate by computational experiments on random graphs with up to 15,000 vertices and on DIMACS benchmark graphs that our algorithm remarkably outperforms other existing algorithms in general. It has been successfully applied to interesting problems in bioinformatics, image processing, the design of quantum circuits, and the design of DNA and RNA sequences for biomolecular computation.
188 citations
TL;DR: In this article, the evolution of a magnesium alloy AZ31 was studied in compression at 673 K (0.73T m ) by optical and SEM/OIM microscopy, and it was concluded that new grain evolution in this alloy is controlled by a deformation-induced continuous reaction.
Abstract: Dynamic grain evolution of a magnesium alloy AZ31 was studied in compression at 673 K (0.73T m ) by optical and SEM/OIM microscopy. The flow curve shows rapid hardening accompanied by a stress peak at a relatively low strain (e p = 0.12), followed by strain softening and then a steady state flow stress at high strains. Fine grains evolved at corrugated grain boundaries at around E P and developed rapidly fluting strain softening, finally leading to a full structure of equiaxed fine grains. Such characteristics of new grain evolution and flow behavior are apparently similar to those in conventional, i. e. discontinuous, dynamic recrystallization (DRX). On the other hand. kink bands were observed frequently near corrugated grain boundaries and also in grain interiors, even around e p . The misorientation of the boundaries of the kink bands increases rapidly during strain softening and approaches a saturation value of around 43°. at high strains. The average size of the regions fragmented by kink bands is almost the same as that of the new grains. It is concluded, therefore, that new grain evolution in this alloy is controlled by a deformation-induced continuous reaction, i.e. continuous DRX.
183 citations
TL;DR: This paper describes a parameterized family of networks and analyzes their connectivity and sensitivity, identifying a network that has an interconnectedness closer to that of a scale-free network, a robustness to attack closer to those of an exponential network, and a resistance to failure better than that of either of those networks.
Abstract: Scale-free networks rely on a relatively small number of highly connected nodes to achieve a high degree of interconnectivity and robustness to random failure, but suffer from a high sensitivity to directed attack. In this paper we describe a parametrized family of networks and analyze their connectivity and sensitivity, identifying a network that has an interconnectedness closer to that of a scale-free network, a robustness to attack closer to that of an exponential network, and a resistance to failure better than that of either of those networks.
174 citations
TL;DR: In vivo near-infrared (NIR) noninvasive blood glucose assay using dermis tissue spectra is reported using one Type 1 diabetic and the correlation coefficient between the blood glucose content predicted by NIR spectra and those measured by finger-prick was 0.928 and the standard error of prediction was 32.2 mg/dL.
Abstract: This paper reports in vivo near-infrared (NIR) noninvasive blood glucose assay using dermis tissue spectra. We assume that the glucose content in dermis tissue traces the variations in blood glucose. For dermis spectra measurements, epidermis, especially stratum corneum, acts as an interference in skin tissue. Thus, we have developed a method for the selective measurement of dermis tissue spectra, enabling us to obtain better quality spectra for an accurate blood glucose assay. The selective measurement of the dermis spectra realized by using a newly developed fiber-optic probe that consists of source and detector optical fibers separated by 0.65 mm on a skin surface. The light path in the skin tissue for this geometry has been simulated by a Monte Carlo method. The simulation results show that detected light mainly interrogates dermis tissue. As the absorbance signal of glucose in human tissue is extremely small, the quality of the measured spectra is critical for the reliable assay. The present method for blood glucose assay has been applied to one Type 1 diabetic. The correlation coefficient between the blood glucose content predicted by NIR spectra and those measured by finger-prick was 0.928 and the standard error of prediction was 32.2 mg/dL. These results demonstrate the potential of our methodology for noninvasive NIR blood glucose assay.
TL;DR: A "square micro-four-point probe method" is devised using an independently driven ultrahigh-vacuum four-tip scanning tunneling microscope, and it is succeeded for the first time to directly measure anisotropic electrical conductance of a single-atomic layer on a solid surface.
Abstract: We have devised a "square micro-four-point probe method" using an independently driven ultrahigh-vacuum four-tip scanning tunneling microscope, and succeeded for the first time to directly measure anisotropic electrical conductance of a single-atomic layer on a solid surface. A quasi-one-dimensional metal of a single-domain Si(111)4 x 1-In had a surface-state conductance along the metallic atom chains (sigma(axially)) to be 7.2(+/-0.6) x 10(-4) S/square at room temperature, which was larger than that in the perpendicular direction (sigma(radially)) by approximately 60 times. The sigma(axially) was consistently interpreted by a Boltzmann equation with the anisotropic surface-state band dispersion, while the sigma(radially) was dominated by a surface-space-charge-layer conductance.
TL;DR: In this article, the detection of a planetary-mass companion to the G9 III giant star HD 104985 from precise Doppler velocity measurements made using the High Dispersion Echelle Spectrograph (HIDES) at Okayama Astrophysical Observatory was reported.
Abstract: We report the detection of a planetary-mass companion to the G9 III giant star HD 104985 from precise Doppler velocity measurements made using the High Dispersion Echelle Spectrograph (HIDES) at Okayama Astrophysical Observatory. The radial velocity variability of this star is best explained by an orbital motion with a period of 198.2 ± 0.3 days, a velocity semiamplitude of 161 ± 2 m s-1, and an eccentricity of 0.03 ± 0.02. Assuming a stellar mass of 1.6 M☉, we obtained a minimum mass and a semimajor axis of 6.3MJ and 0.78 AU, respectively, for the companion. A probable upper limit to the stellar mass of 3 M☉ yielded m2 sin i = 9.6MJ, which falls in the planetary-mass regime. This is the first discovery of a planetary companion orbiting a G-type giant star.
01 May 2003-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the authors proposed to obtain a low-energy beam from an energetic RI-beam leaving a RIKEN projectile fragment separator by using a large gas-catcher and an rf ion-guide system.
Abstract: The projectile fragment separator provides a wide variety of short-lived RI-ions with less restrictions on their chemical property or lifetime limit. The beam energy and quality is, however, not adequate for low-energy beam experiments, in particular for trapping experiments. Recently, one has proposed to obtain a low-energy beam from an energetic RI-beam leaving a projectile fragment separator by using a large gas-catcher and an rf ion-guide system. In off-line and in on-line test experiments, the principle of the rf ion-guide was proven. An overall efficiency of 0.2% for 70 MeV/u 8 Li from the RIKEN projectile fragment separator (RIPS) was obtained so far.
TL;DR: Recent research from the complex systems and negotiation literatures has much to offer to the understanding of the dynamics of this process and suggestions for improving collaborative design are offered.
Abstract: Almost all complex artifacts nowadays, including physical artifacts such as airplanes, as well as informational artifacts such as software, organizations, business processes, plans, and schedules, are defined via the interaction of many, sometimes thousands of participants, working on different elements of the design. This
08 Sep 2003
TL;DR: This paper proposes a novel authentication method called Awase-E, which uses image passwords and integrates image registration and notification interfaces and ensures that it has a higher usability even when it is used through a mobile phone.
Abstract: There is a trade-off between security and usability in user authentication for mobile phones. Since such devices have a poor input interfaces, 4-digit number passwords are widely used at present. Therefore, a more secure and user friendly authentication is needed. This paper proposes a novel authentication method called “Awase-E”. The system uses image passwords. It, moreover, integrates image registration and notification interfaces. Image registration enables users to use their favorite image instead of a text password. Notification gives users a trigger to take action against a threat when it happens. Awase-E is implemented so that it has a higher usability even when it is used through a mobile phone.
TL;DR: In this article, the authors propose a negotiation protocol for binary issue dependencies with a parity-maintaining annealing mediator and an unmediated version of the negotiation protocol.
Abstract: Research to date on negotiation protocols has focused almost exclusively on defining simple contracts consisting of one or a few independent issues and a relatively small number of possible contracts. Many real-world contracts, in contrast, are much more complex, consisting of multiple interdependent issues and intractably large contract spaces. The family of negotiation protocols we've developed make substantial progress toward achieving near-optimal outcomes for negotiations with binary issue dependencies. We propose a simulated annealing-based approach, a refined version based on a parity-maintaining annealing mediator, and an unmediated version of the negotiation protocol.
TL;DR: A new type of Takagi-Sugeno fuzzy model is proposed and an algorithm to identify model parameters is developed to fully take advantage of the sector nonlinearity concept.
Abstract: This paper presents a new fuzzy modeling technique via the so-called sector nonlinearity concept. To fully take advantage of the sector nonlinearity concept, we propose a new type of Takagi-Sugeno fuzzy model and develop an algorithm to identify model parameters. The algorithm consists of two steps. The purpose of the first step is to determine sector coefficients from input-output data. The second part identifies membership functions from the determined sector coefficients and the input-output data. Identification examples illustrate the utility of this approach.
02 Nov 2003
TL;DR: A generic image classification system with an automatic knowledge acquisition mechanism from the World-Wide Web that gathers a large number of images from the Web automatically and makes use of them as training images forgeneric image classification.
Abstract: In this paper, we describe a generic image classification system with an automatic knowledge acquisition mechanism from the World-Wide Web. Due to the recent spread of digital imaging devices, the demand for image recognition of various kinds of real world scenes becomes greater. For realizing it, visual knowledge on various kinds of scenes is required. Then, we propose gathering visual knowledge on real world scenes for generic image classification from the World-Wide Web. Our system gathers a large number of images from the Web automatically and makes use of them as training images for generic image classification. It consists of three modules, which are an image-gathering module, an image-learning module and an image classification module. The image-gathering module gathers images related to given class keywords from the Web automatically. The learning module extracts image features from gathered images and associates them with each class. The image classification module classifies an unknown image into one of the classes corresponding to the class keywords by using the association between image features and classes. In the experiments, we achieved a classification rate 44.6% for generic images by using images gathered from the World-Wide Web automatically as training images.
TL;DR: A diode-pumped chirped-pulse regenerative amplifier with a cooled Yb:YLF crystal with high effective extraction efficiency is developed, attributed to reduced saturation fluence at low temperature and to a high effective pulse energy fluence during regenerative amplification.
Abstract: A diode-pumped chirped-pulse regenerative amplifier with a cooled Yb:YLF crystal has been developed. The output pulse energy is 30 mJ at 20-Hz repetition rate. A high effective extraction efficiency of 68% is obtained, which is attributed to reduced saturation fluence at low temperature and to a high effective pulse energy fluence during regenerative amplification. After pulse compression by use of a parallel grating pair, 18-mJ pulse energy and 795-fs pulse duration are obtained.
TL;DR: A new approach on how to teach a robot everyday manipulation tasks under the "Learning from Observation" framework is described, which is examined by using a human-form robot, which successfully imitates human demonstrations of everyday tasks.
Abstract: This paper describes a new approach on how to teach a robot everyday manipulation tasks under the "Learning from Observation" framework. In this approach, human demonstrations, which are made up of mutual interactions between a grasped object and an environmental object, are observed and a reusable manipulation task model is automatically generated. Most of the similar approaches so far assume that a demonstration can be well understood from a single demonstration. However, a single demonstration contains ambiguity, in that interactions which are essential to complete a task cannot be discerned without prior task dependent knowledge, which should be obtained from observation. To address these issues, a technique to integrate multiple observations of demonstrations is proposed. The demonstrations differ, but are virtually the same task. The shared interactions among all the demonstrations are considered to be essential and a task model is generated from their symbolic representations. Then, the relative trajectories corresponding to each essential interaction are generalized by calculating their mean and variance, and they are also stored in the task model, which is used to reproduce skilled behavior. This approach is examined by using a human-form robot, which successfully imitates human demonstrations of everyday tasks.
TL;DR: In this paper, a study of the disorder-induced D band in the resonance Raman spectra of isolated single-wall carbon nanotubes (SWNTs) is presented.
Abstract: We report a study of the disorder-induced D band in the resonance Raman spectra of isolated single-wall carbon nanotubes (SWNTs). We show that the D-band frequency ${\ensuremath{\omega}}_{D}$ depends directly on the nanotube diameter ${d}_{t}$ and also on the magnitude of the wave vector for the quantized states ${k}_{\mathrm{ii}},$ where the van Hove singularities in the density of states occur. These two effects are manifested in the D-band frequency through the ${\ensuremath{\omega}}_{D}={\ensuremath{\omega}}_{D}^{0}{+C/d}_{t}$ functional form, but with C negative (positive) for the spring-constant- (double-resonance-) dependent processes, thereby indicating that the spring constant softens and the double resonance stiffens the D-band frequencies. In the case of the spring constant effect, ${\ensuremath{\omega}}_{D}^{0}$ is the frequency observed in two-dimensional graphite. The outcome of the softening versus stiffening competition depends on the nanotube diameter range. When plotted over a wide ${d}_{t}$ range, the diameter dependence of ${\ensuremath{\omega}}_{D}$ $(Cl0)$ arises from the softening of the spring constants due to the nanotube curvature, but within a single interband transition ${E}_{\mathrm{ii}},$ whereby the ${d}_{t}$ variation is small, the D-band stiffening $(Cg0)$ due to the double-resonance condition becomes the dominant effect.
TL;DR: In this paper, the first diode end-pumped ceramic laser with this novel solid-state material was demonstrated, achieving a 345mW cw output power with the slope efficiency of 26%.
Abstract: We have succeeded in the fabrication of Yb3+ : Y3Al5O12 ceramics by the nanocrystalline technology and a vacuum sintering method. The first diode end-pumped ceramic laser with this novel solid-state material was demonstrated. The 345-mW cw output power was obtained with the slope efficiency of 26%. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
15 Mar 2003-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: Grain refinement in an as-cast 0.16%Zr modified 7475 aluminum alloy was studied by means of compression at 490°C and metallographic observations in this article.
Abstract: Grain refinement in an as-cast 0.16%Zr modified 7475 aluminum alloy was studied by means of compression at 490 °C and metallographic observations. The σ versus e behavior shows a significant strain softening just after yielding and an apparent steady-state flow at strains of above 0.3. The structural changes are mainly characterized by development of deformation bands at an early stage of deformation ( e ≤0.3), followed by new grain evolution during steady-state flow due to operation of grain boundary sliding (GBS). GBS can result in local lattice rotation and formation of deformation bands in the as-cast coarse grain interiors. The number and the misorientation angle of deformation bands increase with deformation, followed by evolution of new grains in high strain. It is concluded that grain refinement occurs by a deformation-induced continuous reaction; that is continuous dynamic recrystallization (CDRX). A key role of GBS and second phase dispersoids on CDRX is discussed in detail.
TL;DR: The absolute frequency of an acetylene-stabilized laser is measured using femtosecond combs based on mode-locked Ti:sapphire and fiber lasers to establish an important optical frequency standard for telecommunication applications.
Abstract: The absolute frequency of an acetylene-stabilized laser at 1542 nm is measured at its second harmonic (771 nm) by use of a femtosecond optical comb based on a mode-locked Ti:sapphire laser Frequency stability and reproducibility of the acetylene-stabilized laser are evaluated by the femtosecond comb with a H maser as a frequency reference The absolute frequency of a laser diode stabilized on the P(16) transition of 13C2H2 is determined to be 194 369 569 3836(13) kHz The acetylene-stabilized laser serves as an important optical frequency standard for telecommunication applications
TL;DR: In this article, the effect of a rare earth ion on the conversion efficiency of a CdS/CdTe solar cell was investigated by applying a wavelength conversion of the ion.
01 Sep 2003
TL;DR: In this algorithm, an element generates virtual springs between the neighbor element based on information of how many other elements exist in the neighborhood with a certain radius, and this kind of algorithm gives a new principle of self-organizing formation, and its simplicity will be useful for the design ofSelf-assembling nano machines in future.
Abstract: We propose a novel method of self-organizing formation It is assumed that elements are not connected to each other and they can move in continuous space The objective is to arrange elements in a certain spatial pattern like a crystal, and to make the outline of the group in the desired shape For this purpose, we propose a method by using virtual springs among the elements In this algorithm, an element generates virtual springs between the neighbor element based on information of how many other elements exist in the neighborhood with a certain radius Although the elements interact locally, only by virtual springs, and they do not have global information at all, they form a shape much larger than the sensory radius By a simulation study, we confirmed convergence to a target shape from a random state in very high probability This kind of algorithm gives a new principle of self-organizing formation, and its simplicity will be useful for the design of self-assembling nano machines in future
TL;DR: The present study investigates the role of prosodic structure in selecting a syntactic analysis at different stages of parsing in silent reading of Japanese relative clauses with support for the additional prediction that when no boundary is available to be recycled, processing the relative clause construction is more difficult.
Abstract: The present study investigates the role of prosodic structure in selecting a syntactic analysis at different stages of parsing in silent reading of Japanese relative clauses. Experiments 1 and 2 (sentence-completion questionnaires) revealed an effect of the length of the sentence-initial constituent on the resolution of a clause boundary ambiguity in Japanese. Experiment 3 (fragment-reading) showed that this length manipulation is also reflected in prosodic phrasing in speech. Its influence on ambiguity resolution is attributed to “recycling” of prosodic boundaries established during the first-pass parse. This explanation is based on the implicit prosody proposals of Bader (1998) and Fodor (1998). Experiment 4 (self-paced reading) demonstrated the immediacy of the influence on ambiguity resolution on-line. Experiment 5 (self-paced reading) found support for the additional prediction that when no boundary is available to be recycled, processing the relative clause construction is more difficult.