Photoacoustic spectroscopy (PAS) has recently received much attention especially for plant photosynthesis research, because this technique is capable of performing non-destructive measurement without any pre-treatment of specimens. So far we have developed a PAS system equipped with an open photoacoustic cell (OPC), which allows in situ and in vivo measurements of plant photosynthesis of intact undetached leaves. In this study, we have measured photosynthesis reaction using OPC and developed a Confocal Scanning Photoacoustic Microscopy (CSPAM) system, in which PAS is combined with confocal scanning laser microscopy. The system allows simultaneous measurement of acoustic signal and another signal such as fluorescence, and also gives two- and three- dimensional intensity distributions of these signals, thereby giving two- and three- dimensional information about photosynthetic activity of plants.

In long-haul wavelength-division-multiplexed (WDM) transmission systems, signals with shorter and longer wavelengths have self-phase modulation group-velocity-dispersion (SPM-GVD) penalty caused by to the dispersion slope even after the dispersion-compensation at the receiver has been optimized. As a countermeasure, we have already proposed both pre-compensation and post-compensation of chromatic dispersion at the transmitter and receiver for each channel. This method can decrease the channel variation of path-averaged chromatic dispersion along the transmission line, and it can improve the eye opening of the waveform after transmission. We investigated the optimized parameter of chromatic dispersion and chirping at the transmitter. The optimized pre-dispersion compensation parameter R was about 50%. The optimized chirping parameter α was about 3 when the signal wavelength was less than the mean zero-dispersion wavelength. In a single-channel, 5.3-Gbit/s NRZ signal transmission experiment over a 4,760-km straight line, this method decreased SPM-GVD penalty. In a 32-channel, 5.3-Gbit/s WDM transmission experiment over 9,879 km using a circulating loop, this method improved Q-factors for the 1st and 32nd channels by more than 1.5 dB.

In this paper, we propose a peak-weighted cepstral lifter (PWL) for enhancing the spectral peaks of an all-pole model spectrum in the cepstral domain. The design parameter of the PWL is the degree of pole enhancement or pole shifting toward the unit circle. The optimal pole shifting factor is chosen by considering the sensitivity to spectral resonance peaks, the variability of cepstral variances, and the recognition accuracy. Next, we generalize the PWL so that the optimal shifting factor is adaptively determined in frame-by-frame basis. Compared with other cepstral lifters, a speech recognizer employing the frame-adaptive PWL provides better recognition performance.

We have developed spectral separation devices for processing femtosecond pulses. These devices are based on an optical coupler structure with fiber gratings. In a computer simulation, we confirmed that these devices could extract <1 nm bandwidth light with 80% efficiency. We fabricated the spectral separation devices using single mode fibers and highly Ge-doped fibers. These devices successfully extracted narrow spectral light of 0.3 nm bandwidth with 37% efficiency from femtosecond pulses of 40 nm bandwidth. We also fabricated 2-channel spectral separation devices, which could extract the light from each grating channel.

There has been a rapid advance in wavelength-division multiplexing (WDM) and high bit-rate time-division multiplexing (TDM) as techniques for coping with burgeoning demand for transmission capacity. In the past this expansion of capacity has been achieved by 2.5-Gbit/s and 10-Gbit/s WDM using the C-band (around 1550 nm), but research on the 1600-nm L-band (around 1600 nm) is being stepped up to obtain further expansion. With the achievement of 40-Gbit/s speeds, which mark the limit of electrical signal processing, optical TDM, with speeds of 100 Gbit/s, is coming into use. In this kind of high-density, high bit-rate WDM transmission, the occurrence of non-linear phenomena within optical fibers reduces transmission quality, and this raises the importance of technology for suppressing non-linearity and specifically, in the case of WDM transmission systems, of four-wave mixing (FWM). Obviously there is also the problem of signal distortion due to dispersion, so that technology for suppressing cumulative dispersion is also essential. There is also a need for transmission lines with sophisticated dispersion management over a wide band of wavelengths, and it may be consisted of novel fibers.

This paper conducts performance evaluation for a code division multiple access (CDMA) system when channel bands of multiple neighboring CDMA/DSSS are overlapped in frequency domain. It is assumed that all systems adopt direct-sequence spread-spectrum (DSSS) technique and are BPSK modulated by the different carrier frequencies. Automatic power control (APC) is also applied in the interfered system such that the receiver gets the same power from all users. Without loss generality, an additive white Gaussian noise (AWGN) channel is also assumed during analysis. In this paper, the analytic solution of the signal to noise ratio (SNR) is first derived in which both CDMA systems are modulated by different carrier frequencies. This analysis is good for general cases; and the result shows an excellent computational performance. In particular, the result is very close to Pursly's result, when the systems have the same code length with no carrier difference.

We propose a novel Bragg grating filter synthesis method using a Fourier transform of the target scattering matrix. Multiple scattering processes are taken into account by iteration to improve the synthesis accuracy.

This paper describes a crossbar-switch arbiter for a high-speed MAPOS switch. The arbiter uses the following techniques suitable for variable-length frame switching: 1. parallel processing for handling requests from network interfaces and for resource allocation, 2. techniques such as release-on-request, fast back-to-back transfer, and request prefetching to reduce the arbitration overhead, and 3. a resource sampling technique to enable efficient one-shot multicast processing. Our simulation-based performance evaluation and estimation of the scale of its logic circuits indicated that this arbiter can be implemented through simple hardware.

We first reported the simultaneous-propagation effect that the leaky dominant mode can be present on conductor-backed coplanar strips at the same time as the conventional bound dominant mode. We have investigated here numerically and experimentally this effect in detail. Consequently, we have found that it occurs under a certain condition of structural parameters, and also have verified that it affects circuit performance significantly.

To develop distributed applications requires to consider not only functional requirements but also non-functional requirements such as distributions, synchronizations, and scheduling policies. Specifying such non-functional requirements is necessary for supporting on-line capabilities of Autonomous Decentralized Systems (ADS). However, the existing design notations and methods do not address such needs sufficiently enough to develop ADS applications systematically using object-oriented technique. In this paper, we propose an object-oriented design-level support for specifying concurrent, distributed, and autonomous object behaviors in developing dynamic distributed applications. We develop a high-level meta-object protocol called diMOP to deal with object distributions, method synchronizations, and method scheduling policies. In addition, we develop Class Diagram Supporting diMOP (CDSM) and Dynamically Configurable Object Statemachine (DCOS) for specifying non-functional behaviors and dynamic configuration behaviors, by extending the ordinary class diagram and state diagram of UML. A development environment called diMOPer is implemented to support our approach.

Printed transmission lines have been extensively examined so far, but results obtained there are all concerned with the waveguiding conductors with no loss and zero thickness, except very few results. We have recently studied the transmission characteristics of printed transmission lines in detail, when the waveguiding conductors have finite conductivity and thickness, and we have found an unexpected effect that we call a "mode extinction effect. " This effect results in significant changes in the dispersion behavior of the printed-transmission-line fundamental mode. For a critical thickness, it may turn out that such transmission line can not use in open structural configuration, but must always be used by putting into a packaging box. In this paper, we discuss thoroughly this important effect and related results from the standpoints of both the dispersion behavior and the vector field plots. We also show the measured results of the attenuation constant.

This paper describes an improved complementary beamforming microphone array based on the new noise adaptation algorithm. Complementary beamforming is based on two types of beamformers designed to obtain complementary directivity patterns with respect to each other. In this system, during a pause in the target speech, two directivity patterns of the beamformers are adapted to the noise directions of arrival so that the expectation values of each noise power spectrum are minimized in the array output. Using this technique, we can realize the directional nulls for each noise even when the number of sound sources exceeds that of microphones. To evaluate the effectiveness, speech enhancement experiments and speech recognition experiments are performed based on computer simulations with a two-element array and three sound sources under various noise conditions. In comparison with the conventional adaptive beamformer and the conventional spectral subtraction method cascaded with the adaptive beamformer, it is shown that (1) the proposed array improves the signal-to-noise ratio (SNR) of degraded speech by more than 6 dB when the interfering noise is two speakers with the input SNR of below 0 dB, (2) the proposed array improves the SNR by about 2 dB when the interfering noise is bubble noise, and (3) an improvement in the recognition rate of more than 18% is obtained when the interfering noise is two speakers or two overlapped signals of some speakers under the condition that the input SNR is 10 dB.

This paper proposes a fast method of calculating high-order backward Linear Prediction (LP) coefficients for wideband Code Excited LP (CELP) coders operating at around 16 kbit/s. The fast calculation is achieved by a recursive calculation for the high-order autocorrelation of the decoded signal. The recursive calculation can be employed thanks to a novel method of converting the autocorrelation of the decoded signal to that of the residual signal. High-order backward LP coefficients are computed from the autocorrelation of the residual signal using the Levinson-Durbin (LD) procedure. The conversion approximately performs inverse-filtering using LP coefficients representing a corresponding envelope spectrum. Due to the recursive calculation, the proposed fast calculation method achieves 30% to 45% reduction in computations to calculate the high-order backward LP coefficients compared to the conventional method. Subjective tests show that a wideband Multi-Pulse based CELP (MP-CELP) coder at 16 kbit/s with the proposed method achieves comparable coding quality to that with the conventional one with 35% reduction in computations needed for calculation of the backward LP coefficients.

Formal description techniques (FDTs) such as VDM, Z, LOTOS, etc are powerful to develop safety-critical systems since they have strict semantics and mathematical reasoning basis. However, they have no methods or guides how to construct specifications unlike specification and design methods such as Object-Oriented Modeling and Technique (OMT), and that makes it difficult for practitioners to compose formal specifications. One of the solutions is to connect formal description techniques with some existing methods. This paper discusses a technique how to integrate FDTs with specification and design methods such as OMT so that we can have new methods to support writing formal specifications. The integration mechanism is based on transformation rules of specification documents produced following methods into the descriptions written in formal description techniques. The transformation rules specify the correspondences on two meta models; of methods and of formal description techniques, and are described as graph rewriting rules. As an example, we pick up OMT as a method and LOTOS as a FDT and define the transformation rule on their meta models.

We propose a wideband CELP-type speech coder at 16 kb/s based on a mel-generalized cepstral (MGC) analysis technique. MGC analysis makes it possible to obtain a more accurate representation of spectral zeros compared to linear predictive (LP) analysis and take a perceptual frequency scale into account. A major advantage of the proposed coder is that the benefits of MGC representation of speech spectra can be incorporated into the CELP coding process. Subjective tests show that the proposed coder at 16 kb/s achieves a significant improvement in performance over a 16 kb/s conventional CELP coder under the same coding framework and bit allocation. Moreover, the proposed coder is found to outperform the ITU-T G. 722 standard at 64 kb/s.

This paper proposes a method of automatically eliciting knowledge which is used to detect feature interactions in telecommunication services. With conventional methods, the knowledge is provided manually. With the proposed method, the knowledge is automatically elicited as service constraints. In telecommunication systems, when a new service is added, new state transitions are created. In case of new service, the new state should be reached in the state transitions. On the other hand, some states of existing services should not be reached. These constraints can be considered as knowledge for detecting feature interactions. This paper also proposes a scenario for detecting feature interactions using elicited knowledge. This scenario was confirmed as effective.

A software requirements specification (SRS) is a document at the first phase of software development. Since it is difficult to make an accurate SRS at the beginning of software development, we propose a supporting method to detect and interpret the inconsistency of SRS. First, we classify and define the inconsistency of SRS. Next, we describe how to detect and interpret the inconsistency of SRS. We use the Requirements Frame Model to detect the inconsistency of SRS. We apply the Dempster and Shafer's theory to interpret the inconsistency of SRS. We illustrate our method with an example.

This paper describes a scheme to capture a wide-view image using a camera setup with uncalibrated cameras. The setup is such that the optical axes are pointed in divergent directions. The direction of view of the resulting image can be chosen freely in any direction between these two optical axes. The scheme uses eight-parameter perspective transformations to warp the images, the parameters of which are obtained by using a relative orientation algorithm. The focal length and scale factor of the two images are estimated by using Powell's multi-dimensional optimization technique. Experiments on real images show the accuracy of the scheme.

This paper proposes a reference model of CAD system generation, and describes its prototype implementation. The problems encountered in using CAD systems in industry involve complicated data handling and unsatisfied demands for domain knowledge because of the lack of a way of extracting and adopting it in the system. In the example domain of architecture, the authors have already defined domain-specific BDL (Building Design Language) for architecture experts to describe modelers of architectural structure in CAD systems by themselves. Moreover, the authors have developed a CAD system generator based on BDL descriptions. However, the different domain-specific languages required for individual domains create difficulty in developing various CAD system generators. The proposed reference model solves this problem by applying a common intermediate language based on the object model. Moreover, the model allows the creation of an integrated CAD system which contains multiple domains required by a field of industry. Its prototype implementation demonstrates its feasibility.

This paper describes how voltage fluctuation in the DC power supply of a digital IC can be reduced, by means of molding the package-pin in a ferrite-resin composite. The voltage fluctuation of the DC power supply, when the input terminal was driven by a 40 MHz, 5 Vp-p pulse wave, was measured using an oscilloscope. Simultaneously, the voltage spectrum of the fluctuation was measured using a spectrum analyzer. As a result, the voltage fluctuation was decreased by about 50 % when the IC package-pins were molded in a ferrite-resin composite, in which the µiac of the ferrite powder equalled 100, and the powder content was 80 weight-%. In the same IC, there was the reduction effect of the voltage spectrum of the fluctuation was recognized in the frequency range 40 MHz to 1 GHz.