The high-Tc superconducting active antenna proposed here for millimeter and submillimeter radiowave communications, uses a YBCO slot antenna with a series Josephson junction array to increase the normal-state resistance of the junctions, in order to ensure impedance matching between the antenna and the junctions. The antenna is a coplanar waveguide fed slot antenna, which can be easily and monolithically combined with the Josephson junctions. The design frequency of the antenna is 10 GHz and the obtained bandwidth of a VSWR less than 2 was 4.1%. Normal-state resistance values of the junction array could be confirmed by measuring I-V characteristics and 100-MHz impedance measurements, and both agree very well. Microwave mixing experiments were carried out using the junction array with the antenna, and the experiments showed that the conversion gain of the junction was proportional to the number of the junctions. The conversion gain of an eight-junction mixer with the antenna was found to be -6 dB.

Closed-form solutions of the characteristic initial value problem for electric and magnetic fields propagating as nonsinusoidal plane TEM-waves in lossy unbounded media are calculated with Riemann's method and discussed in detail. As an application, the reflection and transmission of waves on a planar boundary is examined, when one semi-infinite medium is lossy.

This work is concerned with a dynamic analysis of complex uniplanar guide-wave structures for MMICs at millimeter-wave frequencies. The enhanced spectral domain approach is effectively used to model such uniplanar structures with trapezoidal conducting strips involving microshielding enclosures. A wide range of line propagation and impedance characteristics is obtained for slotline and coplanar waveguide (CPW). The effect of different conductor profiles on line characteristics is discussed in detail. Results show an excellent agreement with other works. A class of dispersion-related curves are presented for design consideration.

This paper describes analytical results of high-Tc superconducting asymmetric coplanar strip lines using the frequency-dependent finite-difference time-domain method. The propagation constants of the YBa2Cu3O7-x asymmetric coplanar strip line fabricated on the LiNbO3 substrate are reported. The effect of the SiO2 buffer layer is also investigated.

This paper studies the problem of reconstructing a planar surface from stereo images of multiple feature points that are known to be coplanar in the scene. We present a direct method by applying maximum likelihood estimation based on a statistical model of image noise. The significant fact about our method is that not only the 3-D position of the surface is reconstructed accurately but its reliability is also computed quantitatively. The effectiveness of our method is demonstrated by doing numerical simulation.

In this paper, we propose a dialogue model that reflects two important aspects of spoken dialogue system: to be robust' and to be cooperative'. For this purpose, our model has two main inference spaces: Conversational Space (CS) and Problem Solving Space (PSS). CS is a kind of dynamic Bayesian network that represents a meaning of utterance and general dialogue rule. Robust' aspect is treated in CS. PSS is a network so called Event Hierarchy that represents the structure of task domain problems. Cooperative' aspect is mainly treated in PSS. In constructing CS and making inference on PSS, system's process, from meaning understanding through response generation, is modeled by dividing into five steps. These steps are (1) meaning understanding, (2) intention understanding, (3) communicative effect, (4) reaction generation, and (5) response generation. Meaning understanding step constructs CS and response generation step composes a surface expression of system's response from the part of CS. Intention understanding step makes correspondence utterance type in CS with action in PSS. Reaction generation step selects a cooperative reaction in PSS and expands a reaction to utterance type of CS. The status of problem solving and declared user's preference are recorded in mental state by communicative effect step. Then from our point of view, cooperative problem solving dialogue is regarded as a process of constructing CS and achieving goal in PSS through these five steps.

In conventional word-spotting methods for automatic recognition of continuous speech, individual frames or segments of the input speech are assigned labels and local likelihood scores solely on the basis of their own acoustic characteristics. On the other hand, experiments on human speech perception conducted by the present authors and others show that human perception of words in connected speech is based, not only on the acoustic characteristics of individual segments, but also on the acoustic and linguistic contexts in which these segments occurs. In other words, individual segments are not correctly perceive by humans unless they are accompanied by their context. These findings on the process of human speech perception have to be applied in automatic speech recognition in order to improve the performance. From this point of view, the present paper proposes a new scheme for detecting words in continuous speech based on template matching where the likelihood of each segment of a word is determined not only by its own characteristics but also by the likelihood of its context within the framework of a word. This is accomplished by modifying the likelihood score of each segment by the likelihood score of its phonetic context, the latter representing the degree of similarity of the context to that of a candidate word in the lexicon. Higher enhancement is given to the segmental likelihood score if the likelihood score of its context is higher. The advantage of the proposed scheme over conventional schemes is demonstrated by an experiment on constructing a word lattice using connected speech of Japanese uttered by a male speaker. The result indicates that the scheme is especially effective in giving correct recognition in cases where there are two or more candidate words which are almost equal in raw segmental likelihood scores.

This paper concerns the issue of learning strategies for problem solvers from trace data. Many works on Explanation Based Learning have proposed methods for speeding up a given problem solver (or a Prolog program) by optimizing it on some subspace of problem instances with high probability of occurrences. However, in the current paper, we discuss the issue of identifying a target strategy exactly from trace data. Learning criterion used in this paper is the identification in the limit proposed by Gold. Further, we use the tree pattern language to represent preconditions of operators, and propose a class of strategies, called decision list strategies. One of the interesting features of our learning algorithm is the coupled use of state and operator sequence information of traces. Theoretically, we show that the proposed algorithm identifies some subclass of decision list strategies in the limit with the conjectures updated in polynomial time. Further, an experimental result on N-puzzle domain is presented.

Various authors have proposed probabilistic extensions of Valiant's PAC (Probably Approximately Correct) learning model in which the target to be learned is a (conditional) probability distribution. In this paper, we improve upon the best known upper bounds on the sample complexity of the parameter estimation part of the learning problem for distributions and stochastic rules over a finite domain with respect to the Kullback-Leibler divergence (KL-devergence). In particular, we improve the upper bound of order O(1/ε2) due to Abe, Takeuchi, and Warmuth to a bound of order O(1/ε). In obtaining our results, we made use of the properties of a specific estimator (slightly modified maximum likelihood estimator) with respect to the KL-divergence, while previously known upper bounds were obtained using the uniform convergence technique.

A YBaCuO-Nonsuperconductive YBaCuO-YBaCuO coplanar Josephson junction has been fabricated, using Nonsuperconductive YBaCuO thin film deposited on an MgO(100) substrate with intentional and very local damage which was created by Focused Ion Beam. The YBaCuO grown on the damaged section of the substrate turned out to be non-superconductor, due to implanted Ga ions and the change in the crystal quality, facilitating formation of an S-N-S junction. We found the important fact that the critical current density decreased exponentially with inverse of the junction length which was changed from 0.2 to 1 µm, and that Ga ion was detected in the thin films of the junctions, and that the thin films of the junctions were formed by a mixture of an amorphous, a polycrystal and a crystal, which is confirmed by Transmission Electron Diffraction. And the damaged substrate gave rise to Ga segregation and the mixed crystal, which played an very important role to form the normal metallic YBCO thin film of the Josephson junction. All these facts are related with the S-N-S junctions.

In this paper we propose a co-design method for control systems using combination of models. By co-design," we mean a cooperative design method in which the behavior of the entire system is simulated as a single model while parameters of the system are being optimized. Our co-design method enables the various subsystems in the system, which have been designed independently as tasks assigned to different designers in the traditional design method, to be designed simultaneously in a unified cooperative way from the system-wide perspective of a system designer. Our proposed method combines models of controlling and controlled subsystems into a single model for the behavior of the entire control system. After the optimum control conditions are determined through simulation of the combined models, based on the corresponding algorithms and parameters, ASIC design proceeds quickly with accurate verification using iterative replacements of the behavior model by the electronic circuit model. To evaluate the proposed method, we implemented a design environment. We then applied our method to the design of ASICs in three test cases (in a control system and in audio-visual systems) to investigate its effectiveness. This paper introduces the concepts of the proposed co-design method, the design environment and the experimental results, and points out the new issues for system design.

The Double-Sided Rugged poly Si (DSR) technology has been developed for high density DRAMs. The DSR technology was achieved using transformation of rugged poly Si caused by ion implantation. The DSR can increase the surface area of the storage electrode, because it has rugged surfaces on both upper and lower sides. The 2-FINs STC (STacked Capacitor cell) with DSR was fabricated in the cell size of 0.72 µm2, and it is confirmed that the DSR can increase the surface area 1.8 times larger than that of smooth poly Si. It is expected that 25 fF/bit is obtained with a 300 nm-thick storage electrode. These effects show that sufficient capacitance for 256 Mb DRAMs is obtained with a low storage electrode. It is confirmed that there is no degradation in C-V and I-V characteristics. Moreover, the DSR needs neither complicated process steps nor special technologies. Therefore, the DSR technology is one of the most suitable methods for 256 Mb DRAMs and beyond.

A Radial Line Slot Antenna (RLSA) is a planar antenna for DBS reception. It is a kind of slotted waveguide arrays. The conductor loss is so small that high efficiency is expected irrespective of the aperture diameter. On the other hand, since a RLSA utilizes the traveling waves, the frequency bandwidth is limited by the long line effect, particularly for a larger antenna. A new Wide-Band RLSA (WB-RLSA) is proposed which halves the waveguide length and widens the frequency bandwidth. This paper presents the design and experimental results of a model antenna. A gain of 33.7dBi is measured at the edge of 800MHz bandwidth and its high potential is demonstrated.

B-ISDN telecommunication systems will require signal processing speeds up to 600 Mbps or more. We must therefore consider the affects of signal reflection, signal attenuation, time dalay, and so on when designing these systems. The higher the signal speed, the larger the electrical noise induced around the connector, especially in the plated through holes (PTHs) area. This paper presents the results of our investigation focused on connector mounting configurations in the signal transmission line, especially whether or not signals transmit through the PTH in a printed circuit board (PCB). How the signal reflection characteristics depend upon transmission line configurations are discussed and experimental results and simulation analyses for a transmission line system using a small miniature A-type (SMA) connector as an example are performed. It is suggested that designs for future high-speed signal transmission circuits take into account the PTH diameter and/or the PTH pitch conditions, values for which can be determined from simulation analysis.

Many typical control problems such as deadlock avoidance problems and mutual exclusion problems can be formulated as forbidden marking problems. This paper studies a forbidden marking problem in controlled complementary-places Petri nets, which are suitable model for sequential control systems. We show a necessary and sufficient condition for the existence of a control law for this problem. We also obtain a maximally permissive control law which allows a maximal number of transitions to fire subject to a condition that forbidden markings will never be reached.

A new electrostatic wobble motor design and fabrication method were proposed, and micromotors were successfully fabricated and operated. The advantages are (1) thicker structural size, resulting in larger torque, (2) simple and safe fabrication process and (3) needle-shaped bearing to support the rotor. Needle-shaped bearing used here is expected to have lower friction comparing with the existing motor, since the load is smaller for this kind of bearing structure. Two major sources of the load, electrostatic force and capillary force, were considered to prove this tendency. Diamond-like Carbon (DLC) film was employed as a solid lubricant for its bearing. The friction of DLC and that of ilicon-dioxide were compared by experiment.

We developed piezoresistors with an intrinsic compensation of the offset temperature characteristics. High energy ion implantation was applied to fabricate this type of piezoresistor. The dopant profile of the buried piezoresistor resembles to that of the junction gate field effect transistor (JFET). The buried layer corresponds to a channel of JFET, and the substrate bias corresponds to the gate voltage. Owing to the independent temperature varying parameters, i.e., width of the depletion layer and carrier mobility in the channel, the drain current of the JFET has a temperature independent point at an appropriate gate source voltage. The effect was used in the new type of buried piezoresistor which has a driving point of zero temperature coefficient of resistance at an appropriate gate source voltage.

The potential attenuation process of charged human body (HB) is analyzed. A two-dimensional circuit model is presented for predicting the potential attenuation characteristics of the HB charged on the floor. The theoretical equation for the HB potential is derived in the closed form in the Laplacian transformation domain, and the numerical inverse Laplace transform is used to compute it. The half-life or relaxation time of the HB potential for decay is numerically examined with respect to the electrical parameters of shoes. The experiment is also conducted for verifying the validity of the computed result.

The antenna factor measurement of the dipole antennas for electromagnetic interference (EMI) measurements is studied theoretically and experimentally. The 3-antenna method is applied to near-field. Near-field transmission characteristics between the transmitting and receiving dipole antennas is obtained by using the electromotive force (EMF) method, where sinusoidal current distributions are assumed. It is shown that the antenna factors can be measured from transmission values between two antennas and near-field correction factors at any height of each antenna.

A conventional anode coupled plasma etching process has been developed to etch 300 µm-deep cavities and 600 µm-through holes with nearly vertical sidewalls into single crystal silicon. An optimized SF6/O2 gas mixture results in a nearly vertical etching profile. A silicon wafer was fabricated with a large number of cavities and through holes with less than 1 percent uniformity. It was also experimentally confirmed that this process can be used to etch vertical cavities and through holes in single-crystal silicon with any orientation. This process has the advantage of unlimited etching depth and etching patterns. Advantages in mechanical strength are obtained because a micro-curve is formed at the bottom edge of the cavities. This etching process developed on a conventional plasma etching system was utilized to fabricate a torsional vibrator that consists of single-crystal silicon and Pyrex glass.