In this paper, a new trial for the signal processing is proposed along the same line as a previous study on the extended regression analysis based on the Bayes' theorem. This method enables us to estimate a response probability property of complicated systems in an actual case when observation values of the output response are roughly observed due to the quantization mechanism of measuring equipment. More concretely, the main purpose of this research is to find the statistics of the joint probability density function before a level quantization operation which reflects every proper correlation informations between the system input and the output fluctuations. Then, the output probability distribution for another kind of input is predicted by using the estimated regression relationship. Finally, the effectiveness of the proposed method is experimentally confirmed by applying it to the actually observed input-output data of the acoustic system.

Next generation hand-held devices must provide seamless connectivity while obeying stringent power and size constrains. In this paper we examine this issue from the point of view of the Network Interface (NI). We measure the power usage of two PDAs, the Apple Newton Messagepad and Sony Magic Link, and four NIs, the Metricom Ricochet Wireless Modem, the AT&T Wavelan operating at 915 MHz and 2.4 GHz, and the IBM Infrared Wireless LAN Adapter. These measurements clearly indicate that the power drained by the network interface constitutes a large fraction of the total power used by the PDA. We then examine two classes of optimizations that can be used to reduce network interface energy consumption on these divices: transport-level strategies and application-level strategies. Simulation experiments of transport-level strategies show that the dominant cost comes not from the number of packets sent or received by a particular transport protocol but the amount of time that the NI is in an active but idle state. Simulation experiments of application-level strategies that significant energy savings can be made with a minimum of user-visible latency.

Users of computer communication systems and their requirements are rapidly increasing and changing. It is desirable to have a development method which helps to make small changes in a design of a system to obtain another system which satisfies new requirement changes. We propose a flexible synthesis method which adopts designers' requirement changes in formal protocol specifications designed in LOTOS.

Analysis of electroencephalogram (EEG) is presented for sleep physiology. This analysis is performed by the Instantaneous Maximum Entropy Method (IMEM), which was given by the author. Appearance and continuation of featuristic waves are not steady in EEG. The characteristics of these waves responding to epoch of sleep are analyzed. The behaviours of waves were clarified by this analysis as follows; (a) time dependent frequency of continuous oscillations of alpha rhythm was observed precisely. Sleep spindles were detected clearly within NREM and these parameters of time, frequency, and peak energy were specified. (b) delta waves with very low frequencies and sleep spindles were observed simultaneously. And (c) the relationship of sleep spindles and delta waves was first detected with negative correlation along time-axis. The analysis by the IMEM was found effective comparing conventional analysis method of FFT, bandpass filter bank, etc.

This paper reviews recent developments in small-sized broadband antennas for EMI measurements, especially in the microwave frequency region. Transient EMI measurements are also discussed by introducing complex antenna factors and conversion of frequency-domain data into time-domain data. This paper also focuses on considerable improvements achieved in calibration techniques for conventional EMI antennas in VHF/UHF bands.

A simple method based on the pattern integration method for measuring the power absorption by human model in the vicinity of antennas is proposed. Good agreement between the measured and the numerical results is obtained conforming the validity of the present measurement method. The equipment is useful in the EMC measurement and research of the antennas for the portable telephone.

Noise waveform analyzer was developed to measure the statistical distributions such as amplitude probability distributions of noise envelope. Using this system installed in a van, some statistical distributions of automotive radio noise in lower frequency microwave bands (1-3 GHz), received while driving on main streets and expressways in Tokyo, were measured to provide fundamental data for designing mobile communication systems in this frequency band. Variation of the impulse height, received in typical driving conditions, can be expressed by a log-normal distribution and impulse emission seems to be Poisson-distributed in time for time history records as long as 40 minutes.

We frequently use a polynomial to approximate a complex function. This study shows a method which determines the optimum coefficients and the number of terms of the polynomial, and the error of the polynomial is estimated.

Superposed ATM cell streams have burstiness and strong autocorrelation properties. This paper investigates traffic measurement-based modeling method for superposed ATM cell streams. We develop a new measurement method based on monitoring both the waiting time distribution in a monitoring queue and the autocorrelation of cell interarrival times. Through the monitoring queue, we directly observe the queueing effect of superposed cell flows on ATM multiplexers. The measured traffic is modeled as the two-state MMPP. With the measured traffic, we estimate the cell loss probability in ATM multiplexers from the MMPP/D/1/K queue. Our method successfully works with homogeneous and heterogeneous superposition of traffic sources including voice, data, and video. These results can be applied to the evaluation of ATM multiplexers, traffic engineering, and network performance monitoring.

A new magnetostrictive thin-film cantilever actuator and a new thin-film walking mechanism were developed. The actuators were made of magnetostrictive amorphous Tb-Fe and Sm-Fe thin films, deposited on the opposite sides of a polyimide film substrate. These actuators need not power supply cables because they were remotely driven by external magnetic fields. The static deflection of a 3-mm-long cantilever actuator was as large as 100 µm at 300 Oe field. Moreover the application of ac resonant frequency field of the same intensity yielded deflection of above 500 µm. The walking mechanism ran as fast as in the order of cm/s. The forward and backward running were possible depending on the frequency of applied magnetic field. Such unique characteristics suggest that magnetostrictive thin-film actuators are useful in MEMS applications.

We show that the truth of a prenex normal form Presburger sentence bounded only by existential quantifiers (or an EPP-sentence) involving two variables can be decided in deterministic polynomial time. Specifically, an upper bound of the computation for the decision is O(n3u), where n is the number of atoms of the EPP-sentence, and u is the largest absolute value of all coefficients in the EPP-sentence. In the analysis for the upper bound, the random access machine is assumed for the machine model. Additionally, a uniform cost criterion is assumed. Deciding the truth of an EPP-sentence is an NP-complete problem, when the number of variables is not fixed. Furthermore, whether the truth of an EPP-sentence involving two or more variables can be decided in deterministic polynomial time, when the number of variables is fixed, or not has remained an open problem. We previously proposed a procedure for quickly deciding the truth of an EPP-sentence on the basis of a suggestion by D.C.Cooper. We found the upper bound by analyzing the decision procedure. The procedure can be applied to both automated correctness proof of specification in various design fields and detection of infeasible paths in a program. In the procedure, a matrix denoting coefficients of the variables in the EPP-sentence is triangulated.

This study proposes an amplitude limiting type spread spectrum communication to be applied to extremely low power radio wave communicaion and evaluates capability of the code division multiplex. First, changes in output from the correlation device, maximum power, and in allowable noise power are compared by computer simulation for the case where the number of multiplex channels is increased. Second, possible relationship between noise intensity and error rate is measured by actual loading experiments using a device developed for trial purpose. Third, majority decision logic is proposed for the said device to realize amplitude limiting type code division multiplex easily. When the amplitude is limited, the maximum power can be controlled at about 2 dB, and channels with more than half of the number of spread sign can be used. It is revealed that, in the spread spectrum, alteration of the number of multiplex channels is made easy by application of this method.

This letter shows an architectural approach for analyzing real-time aspects of distributed multimedia processing systems. The results of this letter are 1) to propose the concept real-time supporting environments which consist of real-time traffic management/control environment and real-time application environment and 2) to analyze the real-time requirements of such environments.

We describe the design, fabrication, and characteristics of FDM/WDM coupler deposited by TEOS-O3 based APCVD method on silicon substrates. Due to drastically reduced birefringence by APCVD process, completely polarization independent narrow band (100 GHz) Mach-Zehnder type FDM coupler was obtained. We also fabricated 1.3/1.55 µm directional coupler type WDM coupler with very low insertion loss.

For finite Volterra series systems, this paper investigates the stability of the exact model matching (EMM) control we have already presented. First, in order to analyze the stability of the EMM system, we present modified small gain theorems depending on the magnitude of the external input (s) in the cases of one input and two inputs. Next, with the help of the theorem for feedback systems with two inputs, we clarify the condition under which the control system is stable for the reference input magnitude within a certain range, and is also robust for small disturbances. The modified small gain theorems are effective for the stability analysis of the nonlinear feedback control systems which do not have affine finite gain.

Preliminary experiments on non-destructive quantitative analysis of water vapor density in halogen lamps have been carried out. A working curve showing a relation between absorbance and water vapor density was successfully obtained by using frequency-stabilized InGaAsP/InP semiconductor laser spectrometric system.

A requirement specification acquisition method combined with hypothesis-based reasoning and model reasoning is proposed for obtaining service specifications from the ambiguous and/or incomplete requirement specifications of communications services. Errors at an early stage of software development cost more to debug than those at a later stage. Specification acquisition is the most upstream development process. Nevertheless, the system support for specification acquisition is delayed compared with other development phases.' Users do not always have precise requirements. It is therefore inevitable that user requirements contain ambiguities, insufficiencies and even contradictions. Considering this, it is indispensable to support a specification completion method that derives service specifications from such problem requirements. This paper proposes a combined method to obtain consistent and complete specifications from such problem requirements. Communications service specifications can be described by specifying terminal behaviors which can be recognized from outside the communications system(s). Such specifications are described by a rule-based language. Requirement specifications usually have components that are ambiguous, incomplete, or even contradictory. They appear as rule description and/or missing rules. From such requirements, service specifications are obtained by using hypothesis-based reasoning on input requirements and existing service specifications. When existing specifications cannot be used to obtain complementary specifications, a communications service model is used to propose new rules. The proposed methods are implemented as a part of a communications software development system. The system enables non-experts in communications systems to define their own service specifications.

In this paper we propose a method for generating Prolog program code and skeleton C code from a specification of requirements written in DFDs (Data Flow Diagram) and DD (Data Dictionary). This generation of code takes two transformation steps. The specification is transformed into a Prolog program and the transformed Prolog is used for generating skeleton C code so that the specification is directly expendable in the conventional programming environment. This work makes it possible to rapidly have a prototype by executing Prolog programs and remove the design stage from the software development life cycle. This has been implemented on UNIX workstation environment with a data flow diagram editor START system.

In this paper, we propose a camera calibration method that estimates both intrinsic parameters (perspective and distortion) and extrinsic parameters (rotational and translational). All camera parameters can be determined from one or more images of planar pattern consists of parallelogramatic grid points. As far as the pattern can be visible, the relative relations between camera and patterns are arbitrary. So, we have only to prepare a pattern, and take one or more images changing the relative relation between camera and the pattern, arbitrarily; neither solid object of ground truth nor precise z-stage are required. Moreover, constraint conditions that are imposed on rotational parameters are explicitly satisfied; no intermediate parameter that connected several actual camera parameters are used. Taking account of the conflicting fact that the amount of distortion is small in the neighborhood of the image center, and that small image has poor clues of 3-D information, we adopt iterative procedure. The best parameters are searched changing the size and number of parallelograms selected from grid points. The procedure of the iteration is as follows: The perspective parameters are estimated from the shape of parallelogram by nonlinear optimizations. The rotational parameters are calculated from the shape of parallelogram. The translational parameters are estimated from the size of parallelogram by least squares method. Then, the distortion parameters are estimated using all grid points by least squares method. The computer simulation demonstrates the efficiency of the proposed method. And the results of the implementation using real images are also shown.

While high compression ratio has been achieved using recently developed image coding algorithm, the noise removal technique is considered as an important subject. This still holds for very low bitrate video coding, that is, MPEG-4 has defined it as a core experiment which is mainly concerned with block based discrete cosine transform (DCT) coding such as H.263 and MPEG-1. This paper describes a novel and practical technique which attempts to accomplish both noise suppression and detail preservation at the same time. Some of the conventional adaptive filters are designed to search a homogeneous region among the predetermined polygonal subregions, then to apply a smoothing operation within the selected subregion. It shall be, however noted that sometimes the predetermined subregion finally selected may still be hererogeneous. This fact leads us to a novel idea; instead of examining the predetermined regions, define a lot more flexible region likely to be homogeneous. In order to achieve this, we introduce the binary index. each pixel is classified into either the lower intensity group or higher intensity group based on a local statistics. Then a smoothing operation is applied within the pixels having the same group index as the pixel to be processed. Thus our scheme can search a homogeneous region appropriately. The adaptive smoothing adopted in the proposed scheme is also designed to be consistent with an important property of human visual system, i.e., the spatial masking. noise visibility decreases at spatial details such as edges and textures. Another advantage is that it can be realized with significantly low computations. The simulation results show that his approach can suppress the visible artifacts while retaining the fine details such as edge and texture.