The piezoelectric properties in some bismuth layer-structured ferroelectric (BLSF) ceramics were investigated focusing on a mechanical quality factor, Qm. Many BLSF compositions with various Curie temperature, Tc, were selected in this study, and the Qm values of (33) mode were plotted as a function of their Curie temperature, Tc. The Qm increased with increasing the Tc in the low Tc compositions below 500°C. It is considered to relate with the domain wall pinning because the coercive field, Ec also increased with increasing the Tc. However, in the high Tc compositions above 750°C, the Qm decreased with increasing the Tc contrary, because of the difficulties in poling treatment due to the Ec. On the other hand, high Qm values more than 10,000 were obtained in the intermediate Tc compositions between at 500 to 750°C. These values are quite high as the piezoelectric ceramics. The key point of the high Qm in these compositions is the poling process at high temperature of 300°C.
It is known that poling treatment in germanium-doped silica (Ge:SiO2) glass raises their optical nonlinearity and produces the Pockels effect. This means that the poling treatment in Ge:SiO2 produces asymmetricity in the glass. We generated piezoelectricity in poled Ge:SiO2 glass thin films. Tetravalent-metal-doped SiO2 (M4+:SiO2) films were prepared on Si substrates by RF magnetron sputtering. We used germanium, titanium, and tin as doping materials. However, less than a week later, piezoelectricity disappeared almost completely in all the samples. To prevent piezoelectricity from disappearing, we attempted to pin the doping ions. We developed a pinning technique based on the superstructure of a Ge-Ti-Sn:SiO2 and Ge-Ti-Zr:SiO2. The superstructure was very effective in preventing piezoelectricity from disappearing. Furthermore, broadband visible light emission was observed in the proposed superstructure film.
An unknown resonance is studied, which exists near upper stop band of IDT reflection characteristics, for the 43° in-plane rotated ST-cut of quartz SAW resonator. In this study, we analyze the displacement loci of surface wave at first, and find that slight skew angles exist in them. Simple simulation model is introduced to analyze the phenomenon and anti-symmetric model of T matrix explains that phenomenon adequately.
A novel temperature compensated SAW substrate was developed by using direct bonding techniques. This method has merits to keep the same coupling factor and propagation loss as the original piezoelectric substrate and need not strict control of substrate thickness. Temperature compensating method using direct bonding techniques requires support substrate with small thermal expansion coefficient and large elastic coefficients. Sapphire is one of the ideal materials for the support substrate. Thickness of the piezoelectric substrate has large influence on the temperature characteristics and spurious responses caused by reflection of bulk acoustic wave at the bonding interface. We found appropriate thickness of LiTaO3 with good temperature characteristics and no spurious responses. Using bonded LiTaO3/sapphire SAW substrate, US-PCS SAW duplexer with small temperature coefficient of frequency and good frequency characteristics was developed. Power durability of the duplexer using bonded LiTaO3/sapphire SAW substrate was excellent because of high thermal conductivity of sapphire.
In this paper, the bi-mesa resonators, which can be fabricated with very high mesa steps, were fabricated, and their frequency-temperature (f-T) characteristics were measured as an index of the mode-coupling strength. Since the mode-coupling affects to the first-order temperature coefficient of the TS-1 mode, the f-T curve of the pure TS-1 mode rotates clockwise depending on the mode-coupling strength. The experimental results showed that the tendency of the first-order coefficients of the measured f-T data were in good agreement with the calculated mode-coupling strength in the mesa height range of 0 to 50%. These results indicate the validity of the calculated mode-coupling strength between TS-1 and TF modes. It is also showed that choosing lower mesa height is desirable because the face-shear modes caused by the X-Z' boundary tend to couple with the TS-1 mode when the mesa step is very high.
A high accuracy modeling methodology for electrical characteristics of transmission electrodes on SAW substrates is established. In order to design SAW filter accurately, it is necessary to extract precise SAW material parameters from the measurement value of the reference SAW resonator. When measuring the SAW resonator, transmission lines are needed for feeding to contact probes. De-embedding procedure, which removes the influence of transmission lines, is very important for accurate characterization of the SAW resonator. In this paper, we apply the improved de-embedding procedure using SHORT, OPEN and THRU calibration patterns. The de-embedded transmission line is separated four parts and extracted the RLGC equivalent circuit model for each part. Furthermore, we derive the frequency characteristic of resistance element of the transmission line. Finally, de-embedding the transmission line accurately, we can get intrinsic characteristic of the SAW resonator. This method must be very useful to extract SAW material parameters and we can design SAW filters more effectively.
A thin beam of wave usually diverges due to diffraction, which is a limitation of any device using such waves. However, a surface acoustic wave (SAW) on a sphere with an appropriate aperture does not diverge but is collimated, realizing ultramultiple roundtrips along an equator of the sphere. This effect is caused by the balance between diffraction and focusing on a spherical surface, and it enables realization of high-performance ball SAW sensors.
A droplet manipulator working with low driving power was developed by using the surface acoustic wave (SAW) technology. The manipulator was driven at a relatively high frequency of 350MHz to increase the SAW power density. First, a single phase unidirectional transducer (SPUDT) was designed. Because of its low insertion loss of 1.5 dB and high directivity of 10 dB, the SPUDT successfully conveyed a 100 nl water droplet with RF input power of 18 dBm (60 mW). Second, the SPUDT design was extended to a curved transducer to focus and launch the SAW energy into the narrow waveguide. Owing to the increased SAW power density, the required SAW power was reduced to 15 dBm (30 mW) for the 100 nl droplet manipulation. In addition, fabrication of liquid injectors was discussed for the formation of tiny droplet.
To improve the temperature characteristics of SC-cut oscillators without degrading their phase noise and short term stabilities, an oscillator circuit has been designed. This circuit uses an AT-cut resonator as a temperature reference of the output frequency, that is, the oscillation frequency of the SC-cut circuit traces the temperature characteristics of the AT-cut resonator. Experimental results show that the frequency stability for the temperature is improved 30 times better than normal oscillators.
An ultra-wideband amplifier MMIC has been demonstrated for the Ultra-Wide-Band (UWB) standard with InGaP/GaAs Heterojunction Bipolar Transistor (HBT) technology. The fabricated MMIC chip size is only 0.53 mm by 0.93mm. The amplifier MMIC includes all matching circuits on the chip. This amplifier MMIC is applicable to both a UWB low noise amplifier and a UWB transmitter amplifier by changing the collector current. The operating bias currents are 15 mA for a low noise amplifier and 30 mA for a transmitter amplifier. The collector bias voltage is 3.0 V. The MMIC as a transmitter amplifier exhibits a gain of 16 +/-1 dB and a third-order intercept point at the input (IIP3) of 0 dBm with 6.0 and 6.01 GHz signals with equal amplitude level. As a low noise amplifier, the MMIC exhibits a noise figure of less than 3.7 dB from 3.1 to 10.6 GHz.
Crosstalk is induced by a reflected wave of a load connected with a transmission line. Thus, analysis of the reflected wave is important. The reflected wave generated from a nonlinear load is complicated. In order to estimate the complicated reflected wave, we measured the reflected and the incident waves for the nonlinear load, and estimated a dynamic C-V Characteristic that explain a relation between the incident and the reflected waves. This paper reports an simple experimental method to extract reflected waves at a varactor load and estimated results of the dynamic C-V Characteristic of the load. It is shown that the reflected voltage waves simulated using the dynamic C-V Characteristic agree with the measured results.
New FDTD algorithm is proposed for analyzing ultrasonic pulse propagation in the human body, the problem being connected with ESWL (Extracorporeal Shock Wave Lithotripsy). In this method, we do not use plane wave approximation but employ directly the original equations taking account of Lagrangian to derive new FDTD algorithms. This method is applied to an experimental setup and its numerical model that resemble actual treatment situation to compare sound pressure distributions obtained numerically with those obtained experimentally. It is shown that the present method gives clearly better results than the earlier method, in the viewpoint of numerical reappearance of strongly nonlinear waveform.
In Power Line Communication (PLC) systems, medium and low voltage power distribution lines are used as a communication network. However, since no consideration is given to signal transmission characteristics in the high frequency used for PLC systems, reflections caused by impedance mismatches deteriorate transmission characteristics. If channel characteristics of power lines can be estimated by simulation, it will be efficient for the design and the operation of PLC networks. This paper proposes a method to estimate transmission characteristics of a channel model between a transmitter and a receiver installed on a distribution network. Propagation characteristics of PLC signals at each distribution facility is described using two port networks. A channel model is automatically generated from the combination of component models along the topology of distribution network and the locations of a transmitter and a receiver. The proposed method was validated using measurement data of a test distribution network and was proved to be effective.
This paper propose robust gain scheduling control design by intelligent control which uses Fuzzy-Neural Network without model. Proposal methods are as follows, To constitute a robust and capable of automatically gain controlling against the conventional fixed PID control system. To build the Neural Network which learns inverse dynamics as feed forward compensation, and to build 2 degrees freedom control which is the feedback compensation. To propose the control system which adaptively adjusts the gain according to the changes of target errors, and to verified the effectiveness of the proposed method.
In principle feedback control can not change the non minimum-phase characteristics with undershooting phenomenon. An extended inverse function is introduced to realize the stable input-output dynamic inversion of all-pass functions involved in non minimum-phase characteristics. Responses of the non minimum-phase systems can be improved by the combination of the feedforward based on the extended inverse function and the feedback from the minimum-phase state of the object. Numerical example reveals that the feedforward control suppresses the undershooting phenomenon acconmpanied by the responses.
Elevator Group Supervisory Control System (EGSCS) is a very large scale stochastic dynamic optimization problem. Due to its vast state space, significant uncertainty and numerous resource constraints such as finite car capacities and registered hall/car calls, it is hard to manage EGSCS using conventional control methods. Recently, many solutions for EGSCS using Artificial Intelligence (AI) technologies have been reported. Genetic Network Programming (GNP), which is proposed as a new evolutionary computation method several years ago, is also proved to be efficient when applied to EGSCS problem. In this paper, we propose an extended algorithm for EGSCS by introducing Reinforcement Learning (RL) into GNP framework, and an improvement of the EGSCS' performances is expected since the efficiency of GNP with RL has been clarified in some other studies like tile-world problem. Simulation tests using traffic flows in a typical office building have been made, and the results show an actual improvement of the EGSCS' performances comparing to the algorithms using original GNP and conventional control methods. Furthermore, as a further study, an importance weight optimization algorithm is employed based on GNP with RL and its efficiency is also verified with the better performances.
The synchronization is very important technology in the field of Cellular Neural Networks (CNNs) due to its various applications from the biological, environmental to communication points of view. This paper deals with the parametric synchronization phenomena in large-scaled oscillating CNN. When we determine adequate parameters for the amplitude and frequency in the large-scaled oscillating CNNs with non-oscillating cells, the CNN oscillates in various ways depending on their conditions. In this paper, we have exhibited that both multi-amplitude and multi-phase synchronization are generated by their parameters. To demonstrate them, we simulated multi-dimensional CNN of 4 × 4 (16cells), 8 × 8 (64cells) and 16 × 16 (256cells) and checked the synchronization phenomena. Each cell has an inductor L, a capacitorC and a complex nonlinear conductance as i=f(v). We find that the synchronization phenomena are similarly occurred from the small networks to the larger one. We give a basic theoretical viewpoint for interesting numerical experiment results for the synchronization phenomena in this paper.
This paper addresses system identification of a switched system in which each sub-system is expressed by a piecewise affine system. A considered system is expressed by a mixed logical dynamical system for which some design methods have been already known. For identification, in most cases, a number of sub-systems, that is, switching points are given in advance. However, it is not easy to find switching points for multi-variable systems. Therefore, in this paper, we propose a simultaneous identification technique which takes into account a number of sub-systems and parameters of them. The proposed method is applied to several examples to show its effectiveness.
To conduct the electric power transactions effectively and to operate the power system efficiently while maintaining reliability under the deregulated environment, it is required that ATC (Available Transfer Capability) should be calculated at high speed with reasonable precision. In order to address this issue, in this paper, an Artificial Neural Network based estimation method for evaluating Maximum Transmission Capability (MTC), which is a key step but also a highly time consuming process in ATC, is proposed. It is confirmed through simulation studies that the proposed method is capable of estimating MTC (ATC) with high speed and sufficient precision. Furthermore, I examined the reduction of calculation time at learning by using the transient stability index.
A fiber optic powering data link is experimentally investigated using an optical fiber installed outside. Two optical fibers are prepared for parallel use in respect to the powering lights and for a loop structure for the signal light. High power LDs with wavelengths around 1.48μm developed for optical amplifiers are used for the powering light sources. A 1.55-μm CW light is transmitted together with the powering light from the master node and then modulated at the slave node. Stability of the system is clarified by simultaneous propagation of the 10-Gbit/s signal light and the 1.48-μm powering lights. Temperature rising induced by the optical loss near a bending point is also evaluated for practical use.
In order to build the system which enables voice training interactively between the user and system, it is required to output the singing voice with rich sound as a teacher sound. Since the user listen to his own bone-transmitted sound as well as his air- transmitted sound when he utters, it is ideal to mix and output the bone-transmitted sounds with the air transmitted sounds of the teacher sound at the same mixing rate where the user actually listens to his singing voice. Here we present the result of investigation what rate of the air- transmitted and bone-transmitted sounds matches the natural situation of listening in utterance.
A known sufficient condition called “dominance condition” for Schur stability of real polynomials is extended in such a way that the equality is allowed in the inequality relation of the original condition. It is pointed out that two extra inequalities are needed for the extended condition to remain intact, being still a simple sufficient condition for stability of the polynomials. Some cases where the original dominance condition is also a necessary one are identified.