For medical imaging, non-rigid motion analysis of the heart deformability is a nontrivial problem. This paper introduces a new method to analyze the gated SPECT (Single Photon Emission Computed Tomography) imges for 3-D motion information of left ventricular. Our motion estimation method is based on a new concept called normal direction constraint" in that the normal of a surface patch of some deforming objects at certain time instant is constant. This paper consists of the following processes: contour extraction, slices interpolation, normal vector field generation, expanding process, motion estimation for producing a 2-D motion vector field, and deprojection for a 3-D motion vector field. In the experiments, we will demonstrate the accuracy of our method in analyzing the 3-D motion field of deforming object.

By applying Wigner distribution, which has high time resolution and high random noise reducing capability, to the acoustic bio–signals, the possibility of early diagnosis in both intracranial vascular deformation and prosthetic cardiac valve malfunction increased. Especially in latter case, 1st–order local moment of the distribution showed its effectiveness.

The authors have studied mechanism of transition from metallic phase to gaseous phase in contact break arc. For further elucidation of the mechanism, we have carried out spectroscopic measurement. The spectrum measurement system which had high time resolution was composed using two monochromators and a bifurcated image fiber, which had one input port and two output ports. The input port received the arc light, and the two monochromators received the arc light from the two output ports, respectively. The spectral sensitivity of the two monochromators was corrected with a standard lamp. We have measured simultaneously two spectra of break arc for Ag in laboratory air, under the condition where source voltage E=48 V, load inductance L=2.3 mH, and closed contact current I0=6 A. As a result, the time-varying tendency of spectrum intensity is similar for the same element, even if the wavelength is different. And from the comparison of time average spectrum intensity, it is clarified that average intensity for gas spectrum does not attain to 10% of that for metallic atomic spectrum (Ag I, 520.91 nm). In addition, the decrease point of Ag II (ion) spectrum has been found to correspond with the peak of Ag I (atom) spectrum.

An asynchronous spread spectrum (SS) modem for 2.4-GHz wireless LAN has been implemented using an efficient ZnO-SiO2-Si surface acoustic wave (SAW) convolver. The design of the highly efficient SAW convolver was developed at Tohoku University and commercially manufactured by Clarion Co., Japan. The modem can operate under full-duplex transmission in the same frequency range of the 2.4-GHz SS band. The SS modem is based on a direct-sequence/code-shift-keying (DS/CSK) method for the modulation. Pseudo-noise (PN) codes are chosen from a preferred pair of 127-chip m-sequences and the code rate is 14MHz. The asynchronous demodulation is simply realized utilizing the coherent correlation characteristics of the SAW convolver. Under full-duplex transmission, the self-jamming caused by a transmitted signal in the modem itself is effectively reduced by an RF isolator and the SS processing gain. The implemented modem has been tested using a coaxial cable with attenuator. A bit error rate of 10-6 under full-duplex transmission is observed at 78.3dB of a desired to undesired signal ratio. The effective range is estimated on the basis of two-path propagation model. From self-jamming rejection of 78.3dB, the effective range under real-time full-duplex is estimated to be about 200m.

As a general basis for constructing a cooperative and flexible dialogue system, we are interested in modelling the inference process of an agent who participates in a dialogue. For this purpose, it is natural and powerful to model it in his general cognitive framework for problem solving. This paper presents such a framework. In this framework, we represent agent's mental states in the form called Mental World Structure, which consists of multiple mental worlds. Each mental world is a set of mental propositions and corresponds to one modal context, that is, a specific point of view. Modalities in an agent's mental states are represented by path expressions, which are first class citizens of the system and can be composed each other to make up composite modalities. With Mental World Structure, we can handle modalities more flexibly than ordinary modal logics, situation theory and other representation systems. We incorporate smoothly into the structure three basic inference procedures, that is, deduction, abduction and truth maintenance. Precise definitions of the structure and the inference procedures are given. Furthermore, we explain as examples, several cooperative dialogues in our framework.

This paper is concerned with an ITS designed for augmenting a student's capability in problem solving. Discussions are concentrated on helping students acquire strategic knowledge and assisting them to build it in their heads. In this paper, many kinds of strategies are treated from a unified point of view. Based on this consideration, a teaching paradigm of strategic knowledge is presented. The paradigm is realized in an ITS as a training environment for strategic knowledge. Assisting students to learn strategic knowledge, the system sets up an appropriate environment and gives them some appropriate advice in each environment. It is realized as a function of giving them appropriate problems and hints about it. In general, strategic knowledge is a kind of heuristics so that it is not easy to describe their application conditions deterministically and explicitly. For this reason, an ITS for strategic knowledge is required to be designed so as to cover not only the case where expertise is represented explicitly as an executable model but also the case where it is represented only implicitly. To realize this teaching paradigm, situation-dependent knowledge called reminding pattern is prepared in the system. It is represented by a triple of a strategy, a situation, and a key symbol in the situation. It denotes that the key usually reminds students of the strategy in the situation. The system gives students problems including positive/negative examples of applications of each strategy in its problem solving process and hints which remind them of an appropriate strategy and makes them resume the problem solving when they fall into an impasse. In this paper, the structure of the system realizing this teaching paradigm is explained in the domain of proving propositional formulas.

An asynchronous spread spectrum (SS) wireless modem has been implemented using an efficient ZnO-SiO2-Si surface acoustic wave (SAW) convolver. The modem is based on a direct-sequence/frequency-shift-keying (DS/FSK) method for the modulation. The demodulation is carried out asynchronously utilizing the coherent correlation characteristics of the SAW convolver. In order to improve the narrowband interference rejection capability, we propose a new technique based on the reference signal control. A notched-reference-signal circuit and a self-convolution canceler are implemented in the SS modem for the reference signal control. It was found that the antijam capability for narrowband interference is at least -24dB of desired-to-undesired power ratio (D/U); the improvement of the antijam capability is 16dB up as compared with our previous SS modem.

This paper reviews the historical aspect of contributions on the theory of analysis and diagnosis of linear circuits, which have been made by Japanese researchers in these twenty years. On papers of diagnosis, those related to element-value solvability (or determinability) are mainly reviewed. Some important problems are suggested.

In this paper a recursive form of Welch-Berlekamp (W-B) algorithm is provided which is a novel and fast decoding algorithm.

This paper deals with communication model in a software development project when there happens some trouble on it. First, we analyze a communication process in the real projects, and investigate what type of communication exists and which aspect is thought to be important by the members of the projects. Then we propose a communication model based on the analysis. We focus on the communication in case of troubles, and the process is modeled using charge, competence and knowledge of each member in the project. The features of the model lies in the ability to simulate communication route dynamically. The results of the simulation is compared with the real data, and also the use of the model for communication support system is discussed.