The flashover voltage with the backside electrode was lower than one without the backside electrode. Under μs pulse voltage application, we describe about characteristics of creeping discharge developed in narrow gap with the backside electrode. Using CCD camera and ultra-high speed camera, we observed the corona extension processes. As a result, the lowest flashover voltage was obtained in positive polarity of SF₆ content D=3%. In corona extension obtained using ultra-high speed camera, the peculiar differences were observed on the corona extension process. The corona extension increased, and rapid flashover were observed in D=3%. Using CCD camera, the small corona were detected from backside electrode.

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Approximately 150 nm-thick Al-doped zinc oxide (AZO) films with c-axis orientation have been prepared on glass substrates by pulsed laser deposition (PLD) using a split target divided into AZO(Al₂O₃ : 1 wt.%) and AZO(Al₂O₃ : 2 wt.%), which resulted in the adjustment of film composition by changing the ratio (trace ratio) of the time required to irradiate each side of the target alternately by an ArF excimer laser (λ= 193 nm). The film deposition took place at a substrate temperature of 230 °C. The trace ratio of 1 : 1 was employed, resulting in the film component of AZO(Al₂O₃ : 1.5 wt.%). In order to improve the film flatness, D.C. voltage of 150 V was applied perpendicularly to the plume generated between the substrate and the target. As a results, fluctuation of film-thickness improved from 7.8 % for the case without applied voltage to 4.7 %, with applied voltage of 150 V. For the AZO film deposited by irradiating a pulsed laser beam of energy density of 1 J/cm² at repetition frequency of 10 Hz, the lowest resistivity was 2.47×10^-4 Ω·cm for the case without applied voltage and 2.59×10^-4 Ω·cm with applied voltage of 150 V. An average transmittance of more than 85 % in the visible range were obtained for the AZO films fabricated with and without D.C. voltage of 150 V applied perpendicularly to the plume, providing useful functionality as TCO films in the visible range.

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Various types of radars have been developed and used until now—such as Pulse, FM-CW, and Spread Spectrum. Additionally, another type of radar has been proposed recently. The radar measures distance by using standing wave and has been named as “Standing Wave Radar." Standing wave radar has a shorter minimum detectable range and higher accuracy compared to other types. However, the radar can not measure distance down to zero meters like other types of radars. Minimum detectable range of the standing wave radar depends on a usable frequency range. A wider frequency range is required if we need to measure shorter distance. We show a new method for measuring distance down to zero meters without expanding the frequency range. Specifically, we derive an analytic signal, which is a complex sinusoidal signal, by processing the signals obtained from multiple detectors, and we calculate and obtain distances by Fourier transform of the analytic signal. We then verify the validity of our method by simulations based on numerical calculation. The results show that it is possible to measure distance down to zero meters. In our method, measurement errors are caused by gain deviation of the detectors. They are several cm if the gain deviations are less than ±1%. Prevalent radars still have a common defect that they can not measure distance from zero to the minimum detectable range. We expect that the defect will be eliminated by putting our method into practical use.

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This paper proposes a digtal watermarking scheme based on fractal image coding with DCT coefficient and needs no infomation about the original image. In previous work, we have proposed the digital watermarking scheme based on fractal image coding with DCT coefficient between range block and domain block. That had high tolerance for image processing in comparison with conventional scheme. However, it had a problem to have to preserve the information about the original image used for embedding data every image. In the proposal, we choose two parameters in applying fractal encoder among the respective parts, denoted as the even and odd column, so that we can extract data without resorting to the original image. Numerical experiments have been performed in order to measure the validity of the proposal.

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This paper aims at developing a Computer Aided Diagnosis (CAD) system used for the detection of pulmonary nodules in chest Computed Tomography (CT) images. These lung nodules include both solid nodules and Ground Glass Opacity (GGO) nodules. In our scheme, we apply Gabor filter on the CT image in order to enhance the detection process. After this we perform some morphological operations including threshold process and labeling to extract all the objects inside the lung area. Then, some feature analysis is used to examine these objects to decide which of them are likely to be potential cancer candidates. Following the feature examination, a template matching between the potential cancer candidates and some Gaussian reference models is performed to determine the similarity between them. The algorithm was applied on 715 slices containing 25 GGO nodules and 82 solid nodules and achieved detection sensitivity of 92% for GGO nodules and 95% for solid nodules with False Positive (FP) rate of 0.75 FP/slice for GGO nodules and 2.32 FP/slice for solid nodules. Finally, we used an Artificial Neural Network (ANN) to reduce the number of FP findings. After using ANN, we were able to reduce the FP rate to 0.25 FP/slice for GGO nodules and 1.62 FP/slice for solid nodules but at the expense of detection sensitivity, which became 84 % for GGO nodules and 91% for solid nodules.

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Stability analysis of a linear uncertain polynomial system in parameter space is one of central themes of recent control theory. It often requires an enormous number of stability checks with conventional stability test methods. A delta-operator polytopic polynomial, a convex combination of some delta-operator vertex polynomials, is one of such cases. In this paper, robust stability is addressed for polytopic delta-operator polynomials and several necessary and sufficient stability conditions are derived. The delta-operator, an operator used to express discrete-time systems, is known to have significant features; numerical advantage in implementation and ability to smoothly connect z-operator with Laplace operator. Based on this last feature and on the celebrated Edge theorem, we first derive three kinds of exact stability conditions for the uncertain delta-operator polynomials. We then extend the directional stability radius method, which was developed for diamond polynomials, so that it can be also applied to polytopic polynomials. This extension gives rise to the fourth stability test. Furthermore, it is shown from the result of the numerical experiments with these stability analysis methods that one of these four methods, which uses eigenvalues of matrices, turns out to be most efficient for stability analysis of the polytope.

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Scheduling optimization is known as an extremely difficult problem; therefore, many scheduling methods such as linear programming methods or stochastic searching algorithms have been researched to get a better solution closest to the optimum one. After obtaining a certain solution, scheduling managers might have to reschedule another solution that corresponds to changes in requirements or resources. However, rescheduling problems become more difficult as they become larger in their scale. In this paper, we propose an agent-based rescheduling system using linear programming approach. In our system, agents can autonomously conduct rescheduling on behalf of managers by repeating trial-and-error in balancing load or changing priority of resource allocation until it can reach a better solution for the requirement. In addition, managers can make trial-and-error with the help of agents to search another better solution by changing constraint conditions.

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Conciderable skill is needed to detect traffic accident sound which was recorded in the intersection. In this paper, we proposed detection method of accident sound data using time-frequency analysis and correlation method in a short time.

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We demonstrated an active carrier-envelope-phase (CEP) shifter by using a pulse-shaper that controls the spectral phase. Both the CEP-shift and delay-shift are controlled independently by the device. The device was used to actively compensate for a relative CEP-shift imposed by insertion of a dispersive material. We measured the CEP shift by the self-referencing interferometry method and confirmed that the CEP of amplified pulses was actively controlled by the CEP-shifter. The combination of a pulse shaper and CEP-stabilized laser pulses will allow us to design electric fields of optical pulses.

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The generation of supercontinuum spectra from the injection of femtosecond pulses into microstructure or tapered fibers has now been achieved by several groups⁽¹⁾⁽²⁾. In 2001, we have generated the supercontinuum around 1.55 μm by injecting a 100-fs-duration fiber laser pulse with a 1-nJ pulse energy into a 5-m-long highly nonlinear dispersion-shifted fiber. Supercontinuum is a remarkable light source for applications in a lot of fields because of its extreme spectral broadness and the simple generation scheme. These unique properties should make the supercontinuum an ideal tool for important applications including WDM telecommunications, optical coherence tomography, optical-frequency measurement and so on. However, a significant broadband noise on the supercontinuum has been observed to limit its stability. So the supercontinuum is too noisy for many applications.
In this study, we experimentally analyze the correlation among supercontinuum spectra that contribute increasing and decreasing this noise by spectral filtering using spatial light modulator. We observed the formation of correlations among supercontinuum spectra for two fibers which have different properties for chromatic dispersion. We also discuss how nonlinear effects act on the formation of correlations.

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Harmonic imaging is a prosperous technique to obtain a high quality ultrasonic image using harmonics in echoes from microbubbles, i.e., the collapse of microbubbles and subsequent harmonic emission are used for some imaging techniques, such as flash echo imaging. The mechanism of subharmonic generation is not figured out enough however it is considered that there are some relationships between the resonance and collapse of microbubble. On the other hand, subharmonic in echoes from microbubbles is expected to obtain higher contrast between tissue and blood flow than conventional harmonic imaging because it can be hardly detected from tissue. We observed echo signals and images of microbubbles through a microscope simultaneously and investigated the relationship between time-variation of each harmonics component and bubble's behavior. Our results showed clear inverse correlation between decrease of number of bubbles and subharmonic generation.

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When characteristics of microstrip line components are calculated by the FDTD method, a non-reflecting termination of the microstrip line is desired. In this paper, a novel method for making a termination producing a small reflection is proposed. The matched termination is composed of lumped-circuit elements. The frequency range of the analysis is up to 10 GHz. The reflection level of a resistance termination previously proposed increases in the high frequency region. The impedance calculated from the reflection coefficient in the termination shows that the cause of the increase is floating capacitance at the end of the microstrip line. And the other cause is the frequency dispersive characteristic impedance of microstrip line. In order to reduce the effect of the capacitive reactance and the difference between the terminal impedance and the characteristic impedance, a termination using resistance and inductance determined by FDTD and simple circuit calculations is introduced. The reflection coefficient at the proposed termination is 13.5 dB lower than that of the previous resistance termination at 10 GHz.

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The logistic map is known to be one of nonlinear difference equations as a chaos map, and to generate pseudo-random numbers. However, since the chaos has a high sensitive dependency on initial conditions and accumulates inevitable round-off errors caused by iterating the map, the numerical generation of exact chaotic time series is said to be impossible. The aim of this paper is, first, to propose the algorithm to generate exact chaotic time series of a chaos-type function derived from the exact chaos solution. Next, the pseudo-random numbers are evaluated by the four tests and the accumulation of chi-square values. Also, an application to cryptosystems, which do not need the synchronization in usual computer environment, is considered.

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This paper proposes an authentication using fingernail images by using the block segmentation matching. A fingernail is assumed to be a new physical character that is used for biometrics authentication. The proposed system is more effective than fingerprint authentication where psychological resistance and conformability are required. Since the block segmentation matching is useful for occlusion of an object, it is assumed to be robust to a partial change of fingernail. It is expected to enhance the difference of fingernails between persons. The experimental images of various lengths of fingernail and painted manicure were used for evaluation of system performance. The experimental results show that the proposed system obtains the sufficient accuracy to certificate individuals.

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A numerical method of calculating feedback law in quantum mechanical theory of nonlinear optimal control is proposed. We clarify how to derive the feedback formula using a transformation of a characteristic control constant H_R into a pure imaginary number iH_R, which has so far been applied only heuristically. After setting an absolute value of a wave function at terminal time as a function without no singularity in H_R, a phase part of the wave function is expanded as a Taylor series in H_R. According to the expansion, an explicit formula of the feedback law in terms of iH_R is given. This formula fits numerical methods, because the wave function utilized in the formula meets an appropriate spatial boundary condition imposed on generalized Schrödinger equation. of the wave function. Validity of the feedback formula is shown by a numerical simulation study.

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The full-digital audio amplifiers are advantageous with the points of its high power efficiency and its possibility of high fidelity due to the digital signal processing. With the full-digital amplifier, class-D amplifiers are used to drive the load with PWM signals produced from the source signal. Unfortunately, the signals are distorted when the PCM signals are converted to the PWM signals because the pulse-width modulation is a nonlinear conversion from the viewpoint of transient responses. This paper proposes a way to compensate the distortion caused by the pulse-width modulation. A feedforward compensation approach is used because of the simplicity of implementation. The distortion components are estimated with the source signals and its time-derivative signals and used to cancel out them by subtracting them from the source signals. A numerical example with two-tone test is performed to show the effectiveness of the proposed method. The distortion compensation scheme used here may be applicative to other applications.

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Self tuning control (STC) is being used in the field of the process control and various reserch was done. There are generalized minimum variance control (GMVC), generalized predictive control (GPC) and so on as a typical design technique.
In the discrete time domain, there is a problem that an unstable zero occurs when relative order of the numerator and the denominator more than two and we set up sampling period shortened. On the other hand, this problem doesn't occur if it can be designed in the continuous time domain.
In this paper, we propose a new control design method for continuous time system with time delay based on the way of designing GMVC.

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The dissipated energy even of a manipulators must be decreased in order to improve the environment of the earth. This paper describes an optimal path which minimizes the dissipated energy in PTP motions of a vertically articulated manipulator. The dynamic equation of the manipulator is non-linear due to centrifugal-Coriolis, gravity and Coulomb friction forces. Moreover the driving system of the joints has also non-linearity that the generating torque is expressed by polynomial of degree 3 with respect to current. Therefore an optimal path can not be obtained by solving a two-point boundary-value problem analytically.
In this paper an optimal path is searched by the Genetic Algorithm (GA) in the condition that all kinds of non-linear characteristic of the manipulator including a driving system are taken into consideration. The obtained optimal velocity functions are applied to a vertically articulated manipulators with 2 direct-drive motors. The dissipated energy is measured by integrating the input power to the motors. Experimental results agree with the simulation values only when all kinds of non-linearity are taken into consideration.

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A real-option based valuation method has been developed for multi-stage development projects which allow flexible stage-wise go/stop judgments. The proposed method measures the economic value of projects from potential future cash flow produced by them, and is characterized by following four functions: (1) Corporation of technical and market risks into project valuation, (2) Quantification of a project portfolio value, (3) Modeling of correlation between individual projects in a portfolio, and (4) Control of project portfolio risk with a risk index.

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Most of current technologies that enable secure information sharing assume that entities that share information are mutually trustworthy. However, in recent applications this assumption is not realistic. As applications become sophisticated, information systems are required to share information securely even among untrustworthy entities. This paper discusses two kinds of problems about information sharing among untrustworthy entities, i.e. secure statistical data gathering and anonymous authentication, and proposes their solutions. The former is a problem to calculate statistics while ensuring that raw data are not disclosed to any entity including ones that calculate statistics, and the latter is a problem to authenticate entities while keeping their identities confidential.

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In this paper, we propose to use the Simple Principal Component Analysis (SPCA) for dimensionality reduction of the vector space information retrieval model. The SPCA algorithm is a data-oriented fast method which does not require the computation of the variance-covariance matrix. In SPCA, principal components are estimated iteratively so we also propose a criteria to determine the convergence. The optimum number of iterations for each principal component can be determined using the criteria. Experimentally, we show that the SPCA-based method offers improvement over the conventional SVD-based method despite its small amount of computation. This advantage of SPCA can be attributed to its iterative procedure which is similar to clustering methods such as k-means clustering. On the other hand, the proposed method which orthogonalizes the basis vectors also achieved much higher accuracy than the conventional random projection method based on k-means clustering.

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We are studying a coding process of 3-dimensional urban maps that require large amount of memory space, in order to let the maps be available with less system resources. As the first step, we developed a segmentation method of building surface images, which provides an extraction of repetition patterns that will be important in efficient coding of the images. Utilizing the characteristics of the building surface images, we designed a method including the repetition extraction based on “1D image" that is made from vertical or horizontal averaging of an image pixel array. We applied the method to several images and obtained adequate results.

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Wrong:Since the oil crisises
Right:Since the oil crises

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Wrong:the birateral network
Right:the bilateral network

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Wrong:such as gamie theory
Right:such as game theory

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Wrong:transportaion systems
Right:transportation systems

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Wrong:an interdisplinary area
Right:an interdisciplinary area

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Wrong:Air conditioning Systems
Right:Air Conditioning Systems

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Wrong:Graduate School of engineering
Right:Graduate School of Engineering

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