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Discharge voltage prediction of engineering gap configurations is a great challenge for external insulation design in high‐voltage engineering. This paper presents an air gap discharge voltage prediction model based on the support vector regression (SVR). A series of features are defined on the shortest interelectrode path of an air gap, and they are extracted from the electric field calculation results using the finite element method. These electric field features are considered as the input parameters of the SVR‐based model, and the output is the air gap discharge voltage. The genetic algorithm is used for parameter optimization of the SVR model. Trained by a few experimental data of the Institute of Electrical and Electronics Engineers standard rod–rod gaps, this model is applied to predict the standard lightning impulse flashover voltages of parallel gaps for insulator strings under different gap configurations. The prediction results coincide well with the experimental data collected from previous publications. The mean absolute percentage error of the eight test samples is within 4.07%, which is acceptable for engineering applications. The SVR‐based model may be helpful to guide the structure design and insulation coordination of parallel gaps and insulator strings, thus reducing the required full‐scale tests. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

This paper describes an adaptive array antenna using a signal processing system which is implemented by a systolic array processor (SAP), SAP-AA. Computer simulations show the behavior of the SAP-AA against multipath fading. The SAP realizes a parallel pipelined processing by regularly placing many SAP cells with identical functions and structures so that it achieves the high throughput rate in the data processing. Also, the SAP has many desirable features for very large-scale integration (VLSI) system design and enables miniaturization, weight reduction, and mass production of the processing equipment. In this paper, first, the SAP-AA is described which realizes the least squares (LS) algorithm based on the QR decomposition for the input data matrix using the Givens rotations. In addition, the fundamental performances of the SAP-AA are studied including both the transient response and the steady-state behavior in multipath signal environments. To date, there has been no report which treats the multipath signal suppression performance of the SAP-AA. Finally, it is concluded from the discussion that the SAP-AA is effective for unwanted signal suppression in a multipath signal environment. [ABSTRACT FROM AUTHOR]

This paper considers a slotted ALOHA network which consists of a central base station and many mobile terminals. In classical performance analyses of random access networks, a channel between the station and a terminal is assumed to be always in a good state. However, this is not the case in mobile radio networks since the channel suffers from many factors such as fading, shadowing, and so on. Moreover, the channel condition changes with the terminal location. In this paper, a simple channel model is used to consider the effects of time-varying channels in a random access network. The channel model assumed in this paper has three states: shadowing, good, and bad. The transitions between the channel states are described by a Markov chain. The dynamic performance of a slotted ALOHA network over such time-varying channels is evaluated by means of the equilibrium point analysis. Then the influence of the time-varying channel on the throughput performance of a slotted ALOHA network is studied. [ABSTRACT FROM AUTHOR]

This paper proposes an application method of the cooperative distributed multiagent model in multipath allocation algorithm and confirms its valid calculation results by realizing this model in a distributed computer environment. The multiagent model in this paper is an environment where each agent has the same function of asynchronous and parallel calculation and no globally controlling agents exist. To realize this model, this paper proposes an appropriate dividing method of the multipath allocation problem for asynchronous and parallel calculation, a unifying method of each agent's answers end interagent communication protocols. It also compares the required calculation time and the number of allocated paths of a single agent with that of the multiagents end shows the practical calculation ability of the multiagent model. [ABSTRACT FROM AUTHOR]

This paper considers the Z-channel, which is known as a channel model for photon communication or semiconductor memory. A new decoding algorithm is proposed and discussed. Recently, studies have been made from various viewpoints on the asymmetrical error-correcting code suited to the Z-channel, which is considered interesting. One of the basic problems in the Z-channel is the performance and the decoding method when the cyclic code with various features is applied, but it has been investigated little. This paper presents first a maximum-likelihood decoding algorithm which is highly efficient for the cyclic code on the Z-channel. It is then shown that by providing a certain threshold for the algorithm, a higher-speed decoding is realized. It is shown also that by setting the threshold above a certain value, the computational complexity can be improved without sacrificing the maximum-likelihood property. Finally, it is demonstrated by numerical calculation that the decoding error probability is improved greatly by the decoding algorithm proposed in this paper, together with a drastic improvement in the computational complexity. [ABSTRACT FROM AUTHOR]

This paper proposes a new method for efficient validation of the telecommunication protocol, containing the internal events, including those for the timer and resource management. The proposed validation method first converts the protocol containing the internal event into the equivalent protocol not containing the internal event. Then the original protocol is validated by applying the already-proposed validation method for the protocol not containing the internal event to the result of conversion. This paper discusses mainly the principle and the algorithm of the protocol equivalent conversion. The features of the proposed validation method are that the protocol is validated with the minimum processes and signals, which reduces the processing time and the memory capacity needed in the validation and also improves the efficiency. [ABSTRACT FROM AUTHOR]

This paper presents an optimization procedure using tile stochastic model function, aiming at the application to the optimization of the circuit constant in the integrated circuit. The optimization of the circuit constant is formulated as a minimization problem for the objective function derived from the circuit response under the specified condition. In the method presented in this paper, the model function is constructed which approximates well the objective function, and the objective function is minimized by minimizing the model function. The features of the method are that the algorithm is simple, the number of evaluations of the objective function is small, the result depends less on the initial value, and the minimum of the objective function can be determined with a high accuracy. The method is evaluated using the standard test function, and it is verified that all minimum values of the objective function can be determined with n high accuracy with fewer number of calculations of the objective function. The optimization procedure is applied to two circuit examples: the analog control circuit and the inverter chain. The result is satisfactory and the usefulness of the presented optimization procedure in the circuit design is demonstrated. [ABSTRACT FROM AUTHOR]

The systolic array is a scheme for parallel processing and provides an architecture which is suited to a high-speed operation. Consequently, the systolic array has been applied to the system for which the high-speed processing is required, but not to the system for which the reduction of the circuit scale is required. This paper demonstrates that the principle of the systolic array can be applied as a means of reducing the circuit scale. By the proposed method, the circuit scale can be reduced in the system based on the systolic array, without an appreciable modification of the connection in the array and the control. This paper discusses the Reed-Solomon (RS) coder-decoder based on the systolic array as an example, and shows that the circuit scale can be reduced simply. By this system, the RS coder-decoder can be realized in a simple way by the small circuit scale, corresponding to the processing speed of the system. [ABSTRACT FROM AUTHOR]

In this paper, the Rationally Oriented Forgettable Profit Sharing method (RFPS) for reinforcement learning is proposed. Although profit sharing (PS) provides good performances in real environments, its learning is often slow in long-term tasks because it is difficult to determine the appropriate discount rate which satisfies the Miyazaki rational theorem. There are several rationality-relaxed PS methods which work well for such tasks. However, these PS methods may result in many irrational loops. The proposed method fulfills rationality by forgetting the reinforced irrational loops. This method can be easily combined with ordinary PS methods and performs well in long-term tasks. Simulation results show that the proposed method can learn more efficiently than conventional PS methods. [ABSTRACT FROM AUTHOR]

In array antennas, sometimes the desired radiation pattern cannot be obtained due to coupling between element antennas, reflections from the surroundings, or amplitude and phase error of the power supply circuits or failures. In these cases, it is necessary to regenerate the desired radiation pattern by estimating the excitation amplitude and phase of the array antennas. Among methods of estimation of the excitation amplitude and phase, the rotation element field vector method of element antennas is used for the phased array antenna with variable phase shifters, and the planar near-field measurement method is used for the array antennas with no variable phase shifters. The former is limited to phased array antennas, and the latter requires a large-scale scanner for the measurement and results in increased measurement time with larger-scale array antennas. In this paper, we propose a method of estimation of excitation amplitude and phase using the radiation pattern of array element antennas and the measured radiation pattern of the array antennas. Two methods are proposed here; the first method of estimation is the least-squares method using the electrical field as the measured radiation pattern, and the second is the repeating calculation method using the electrical power as the measured radiation pattern. We describe here the principle and experimental results when the first method is used, and the principle and the effectiveness of selection of the initial value for the second method is confirmed by numerical results. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(9): 102–110, 2000 [ABSTRACT FROM AUTHOR]

A small antenna with a size of 1/15 to 1/5 wavelength, consisting of a toroidal coil of fixed length, is proposed. The radiation characteristics of antennas with a limited range of turn numbers and pitch angles are analyzed by the conventional method and the method of moments. The conventional method is based on the assumption of a cosinusoidal current distribution along the antenna element. The results are then compared with experimental results. It is found that the method of moments with correction for the resonant frequency expresses well the characteristics of this small-size antenna, and that fairly good agreement between the results of the conventional method and the experimental results is obtained. For the limited size range adopted in this paper, the proposed antenna offers the advantages of having the same radiation pattern as a one-wavelength loop antenna, allowing easy matching to a coaxial line, and achieving a relatively high gain despite its small size. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(9): 10–19, 2000 [ABSTRACT FROM AUTHOR]

The main problem of an indoor infrared (IR) wireless system via diffuse infrared link is bit error rate (BER) performance degradation due to intersymbol interference (ISI) induced by multipath distortion. In the previous study, only a rectangular pulse was employed as a transmitted pulse. However, multipath distortion tends to make the nondirected diffuse indoor IR channel have a low-pass frequency characteristic, and thus a rectangular pulse, whose spectrum has a form of sinc function, induces much ISI. In this paper, we analyze the BER performance of indoor IR wireless system via diffuse link employing different kinds of pulse waveforms, such as a Gaussian pulse and a raised cosine pulse, and consider the effect of ISI. Moreover, we analyze the BER performance employing a return-to-zero (RZ) pulse which has a guard interval in a slot. It is shown that the RZ Gaussian pulse is effective in mitigating the effect of ISI. © 2000 Scripta Technica, Electron Comm Jpn Pt 1, 83(9): 33–43, 2000 [ABSTRACT FROM AUTHOR]

This paper reports on the reliability improvement of Al-gate power GaAs-MESFET (FET) formed by the photoresist liftoff process (PLP). Al electromigration (EM) tolerance improvement with a higher deposition rate and lower outgas photoresist, a gate breakdown voltage (BVgd) improvement with fine recess control for the channel layer, and the mean time to failure (MTTF) at the 1-dB gain compression point in high-temperature RF operating life tests (HTRF) are described. We observed the parameters of the median time to failure (MTF) with high-temperature forward-bias tests (HTFB), as well as BVgd, and the gate current. The contributions of these parameters to MTTF are estimated by using an RF gate current simulation. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(7): 22–30, 2000 [ABSTRACT FROM AUTHOR]

An optical circulator function has been realized without using any magnetooptic effect by placing a multimode tapered bending waveguide made of passive material in rotational symmetry. The higher-order propagating mode components selectively radiate from a bend of a certain curvature, and the lower-order mode components pass through the bend and radiate from the tip of the taper. When the lower-order modes are launched into the waveguide, light radiates from the tip, and couples to the propagating higher-order modes of the next waveguide at its bending section. This phenomenon is accompanied by a change in the transmission mode distribution and an excess loss of at least 3 dB. However, if the evaluation is only by the transmitted power, the device exhibits the circulator function. This small and low-cost optical device is effective in a low-speed and short-distance bidirectional data communication system. In this paper, in order to confirm the basic principles, microwave simulation was carried out to examine in detail the radiation characteristics from the tapered bending waveguide with a resolution of one wavelength. An extinction ratio of more than 18 dB was realized when the distance between the adjoining waveguides was about one wavelength. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(7): 31–40, 2000 [ABSTRACT FROM AUTHOR]

In the present paper, a new method of selective image amplification using two photorefractive BaTiO3 crystals is proposed and the amplification characteristics of this method are investigated. The gain of beam amplification obtained using the proposed method is almost equal to the product of the gain obtained from each crystal. The rise time of the amplification output also changes when the signal beam power changes with time. The blurring of images caused by the amplification reveals a very small region. The images obtained using this method are more distinct than those obtained using single BaTiO3 crystals, and amplified images obtained by the selective image amplification are of high quality. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(7): 14–21, 2000 [ABSTRACT FROM AUTHOR]

As radio communication has progressed, reduction of intersystem interference has become a problem. In a conventional interference canceller, the interference signal as a source of cancellation is obtained at the receiving station and the interference component in the desired signal is canceled based on this interference signal. However, the interference signal for cancellation may not be obtained at the receiving station. As a remedy, an extraction and reinjection-type interference canceller has already been proposed. In this paper, a pre-interference canceller is proposed in which, if the transmitting station of the desired signal and that of the interference signal are identical, the interference signal is mixed with the desired signal from the transmitting station beforehand and the interference signal leaking into the desired signal is cancelled at the receiving station. First, the applicable range and the fundamental configuration of the present canceller are presented. Subsequently, the method for determining the amplitude and phase of the interference signal injected into the desired signal of the transmitting station and the method for evaluation of the cancellation effect are presented theoretically. Next, an experiment is carried out with the desired signal of 16 QAM or 256 QAM and the interference, signal of 256 QAM. Interference improvement by about 20 dB is obtained for both the 16 and 256 QAM signals. Also, the response speed of control for the fading is 60 ms. In addition to the validity of the theoretical results, effectiveness of the proposed canceller is shown. [ABSTRACT FROM AUTHOR]

Nonregenerative repeating systems on digital microwave radio have the advantage of network flexibility and low-cost transmission. This paper describes a means of compensating self-interference passing adjacent channels (S-IPAC), which degrades the transmission performance. This interference is specific to nonregenerative repeating systems. A transversal equalizer with multitaps is discussed as a countermeasure against S-IPAC. Bit error rates (BER) and signatures are presented theoretically and experimentally as a parameter of hop numbers. [ABSTRACT FROM AUTHOR]

In general, an optimum quantizer which gives the minimum distortion at a given bit-rate is uniquely determined when the statistical characteristics of the source signal are given. This quantizer, however, is not optimum for the human visual characteristics; and a quantizer which is designed to minimize the estimated distortion (estimated noise) reflecting the human visual characteristics is more likely to be optimum. In the optimum quantization of orthogonal transform schemes, theoretical quantizer design schemes considering only the human visual characteristics of the spatial frequency direction have so far been reported. However, there is another human visual characteristic, that is, the noise-masking effect which is the difference in the detectability of noise, depending on the local variation of a video signal (activity). For this, only the quantizers which use this effect experimentally have been reported; and they have not been studied theoretically. In this paper, it is proposed, as the first step, that the visual sensitivity to noise be expressed on two axes, i.e., spatial frequency and ‘activity.’ A three-dimensional (3-D) structure quantization cube is then proposed which is obtained by minimizing the noise estimated by the visual sensitivity of the noise at the given bit-rate and the theoretical design scheme of this optimum quantization cube is described. Finally, the effectiveness of the quantization cube designed by this theoretical scheme is compared with that of the conventional quantization schemes by a computer simulation using real picture data. [ABSTRACT FROM AUTHOR]

The TDMA scheme, a typical multiple-access scheme, can provide secure transmission; but its efficiency is poor under low traffic conditions. By contrast, the random access scheme, represented by the ALOHA scheme, has a small-delay characteristic under low traffic conditions but a stability problem under heavy traffic conditions. This paper presents a new multiple-access scheme in which each station is assigned a slot in every frame and stations are assigned to a slot at different power levels to obtain the capture effect. Therefore, the proposed scheme can adapt itself under various traffic conditions with channel status monitoring based control. Different models of capture effect are proposed, and the performance of the models is analyzed both by theory and by computer simulation. [ABSTRACT FROM AUTHOR]

A two-wire voice-band automatic gain control (AGC) with echo cancellers is studied and applied to an automatic call-transfer repeater. A four-wire circuit model of the amplifier and its stability are discussed. Fast tracking and/or stabilizing AGC using variable-rate control is proposed. Also, a singing protection control method in which the dominant path is selected depending on voice signal powers of the two speech paths is proposed and investigated. The amplifier gain of the inferior path is computed using the measured echo return loss (ERL) values of the echo cancellers. Furthermore, an automatic call-transfer repeater prototype that is based on the new AGC amplifier and its characteristics is introduced. The maximum amplifier gain of the proposed methods is about 10 dB higher than that of a conventional two-wire amplifier with a voice switch. The configuration and algorithms proposed in the paper are proven to be effective for two-wire amplifiers. [ABSTRACT FROM AUTHOR]

The in-house information communication network using local area network (LAN) is required to cope flexibly with the expansion/modification of the system and to avoid the system-down in the generation of a fault by detaching the fault domain. This paper considers the star-ring LAN with the ring spurs and a dual ring. It proposes also the structure and control of the wiring concentrator of ring LAN with the dedicated automatic reconfiguration control by the ring spur bypass and the ring wrapback. Since the ring contains both the ordinary terminals and WC, the reconfiguration-dedicated medium access control (MAC) frame is introduced anew and can be sent only by wiring concentration (WC), making unnecessary the specification modification of the MAC layer of the terminal. The WC which handles the localization and detachment of the fault point is determined by this mechanism. The test ring is automatically expanded from the local ring in WC to the ring containing the ring spur and the ring containing the dual ring successively by testing the conductivity. Using WC, a ring LAN system with the automatic ring degeneration/expansion function can be realized, while providing the terminal with the function of connection/detachment/shift on LAN (hot-pluggability). The time required for reconfiguration by the proposed reconfiguration control is evaluated by summing up the times for the major control steps and by experimental examination. [ABSTRACT FROM AUTHOR]

This paper discusses a PSK modulation/demodulation method free from interruptions providing continuous telecommunication services. The feature of the system is that the transmission rate or the carrier frequency is switchable without interruptions during communications. Functions of the system are outlined. The design procedure and design results are presented. Another feature of the proposed method is its transmission format, in the normal operation, a control information is inserted into the transmission format and a preamble is inserted only when the transmission rate or the carrier frequency is to be changed. By this elaboration, interruptions can be, avoided. As a detailed example of the design, a link configuration is assumed where the convolution encoding Viterbi decoding with coding rate of one-half is used as the forward error correction scheme, and the information rate is made variable among 2B + D, B + D, and D based on the basic ISDN service. Parameters concerning the transmission format and the modulation/demodulation are determined. The control information and protocol required m the functional switching needed in avoiding interruptions are also discussed. By this method, limited radio frequency resources can efficiently be utilized, appropriately varying the transmission rate according to traffic or switching the carrier frequency. [ABSTRACT FROM AUTHOR]

Integrated train access protocol for a high-speed ring network is proposed in this paper. Using the concept of the train, synchronous and asynchronous traffic is integrated. To consider the fundamental performance, the periodicity of the channel activity is found in the steady state, and the cycle length is derived. On the basis of this cycle length, the tram length, channel utilization, and access interval of each traffic are derived. To characterize the proposed protocol more clearly, it is compared with fiber distributed data interface (FDDI), which uses the timed token scheme. As a result, it is shown that the proposed protocol and FDDI have the same high channel utilization. On the mean access interval of the asynchronous traffic, FDDI shows the increase character with the target token rotation time (TTRT), while the proposed protocol shows the decrease character with the number of asynchronous frames contained in the train γ. [ABSTRACT FROM AUTHOR]

This paper presents a data compression scheme which uses the statistical properties of ordered dither image by vector reputation. When a part of the dither image corresponding to n × n dithering matrix is described as a vector, it is observed that there is high correlation ratio between neighbor blocks for level information (the number of black pixels in the vector), the resolution information (the number of kinds of vectors) is a few, and their frequency distribution is very biased. Thus, if these two kinds of information on vector are coded separately by the variable length coding scheme, then high compression ratio can be attained for transmission and storage of dither image. [ABSTRACT FROM AUTHOR]

This paper discusses a satellite TDMA system with two dispersive delay lines of opposite characteristics in earth stations and in the satellite transponder to reduce the peak transmitting power of the earth stations. Reduction effect is estimated for available SAW devices and the reduction in peak transmitting power of about 27 dB is achieved in the single-pulse transmission mode. In actual TDMA systems, however, burst pulses must be transmitted and bursts of about 1000 symbols in length are used. Since only relatively short bursts (about 20 symbols long) are allowable in this system, various study subjects are discussed to realize it, such as the increase of burst length, reference time establishment at earth stations, modulation/demodulation and clock recovery. The effects of several kinds of system impairments, such as residual response of modulator, effect of characteristic deviation of dispersive delay lines, and dynamic range of receiver amplifier of transponder are studied. [ABSTRACT FROM AUTHOR]

This paper considers the primary distributed-type switching network which serves as the prototype for the distributed switching network. A method is shown to determine the route with the minimum number of tandem stages from the originator to the destination nodes in the network (called shortest route). The shortest route is given either by the straight path directly connecting the originator and the destination switching nodes, or, if such does not exist, by the following path. Consider the parallelogram that directly connects the originator and the destination switching nodes. Then the route is obtained from the originator switching node to the destination switching node by connecting arbitrarily the unit links on the border and the inside of the parallelogram, in the same direction as that of the edges of the parallelogram from the originator switching node to the destination switching node. The number of shortest routes between the originator and the destination switching nodes increases following the exponential function of the distance between the originator and the destination switching nodes. The number of tandem stages in the shortest route increases linearly with the distance. If a honeycomb-type network is employed, the number of tandem stages in the shortest mute can be reduced by approximately 15 percent at the maximum, compared to the grid-type network. When a failure such as blocking is produced between the originator and the destination, there exist three kinds of shortest mutes depending on the point of generation. [ABSTRACT FROM AUTHOR]

Stress migration (SM) has become a serious issue with the development of surface acoustic wave (SAW) devices for high-frequency application. For the first time. this paper discusses epitaxially grown Al electrode films as a countermeasure to SM. It also discusses a method of epitaxial growth of Al electrode films tot an SAW resonator deposited onto quartz substrates. It is found that an epitaxially grown film has been fabricated under relatively moderate deposition conditions in vacuum evaporation. The orientation relation for this epitaxial growth is (311)<2&3macr;33>Al//(032)(100)SiO2. The SM lifetime for the SAW resonator thus obtained is found to be more than 2000 times longer and the allowable power value is improved by one order of magnitude more than that usually obtained for polycrystalline Al films with Cu. A discussion of the epitaxial growth mode and lifetime of electromigration also is presented. [ABSTRACT FROM AUTHOR]

Although a trellis-coded modulation scheme has been applied to multilevel PSK or QAM signals, its application for the continuous-phase FSK (CPFSK) with the limiter-discriminator detection has not been investigated well and the coding gain associated with it has not been obvious yet. In this paper, using a linear approximation, we have designed modulation parameters of this scheme. We have also executed the exact computer simulation and made clear the problem to obtain the actual coding gain as well as to increase them. Furthermore, utilizing the intersymbol interference caused by the IF filter, which greatly deteriorates the bit error rate (BER) performance in this scheme, we have proposed a sequence estimation scheme using the Viterbi algorithm. In this scheme, the sending signals are those of the binary continuous phase FSK. Through computer simulations, we have made clear that large improvements of BER really exist. The sequence estimation scheme is considered to work better than the trellis encoded scheme when considering the BER performance and the complexity of transmitter and receiver. [ABSTRACT FROM AUTHOR]

Recently, many methods have been reported for transforming fuzzy multiple-objective linear programming (MOLP) problems, However, the transformation into a crisp MOLP problem requires an extremely large number of constraints and decision variables which is the main disadvantage of these approaches. This paper proposes that a maximizing MOLP problem with trapezoidal positive fuzzy coefficients can be transformed into a crisp MOLP problem without increasing the number of constraints by basing the two indices on the inequality relation between trapezoidal fuzzy numbers. The usefulness of the proposed method is demonstrated. [ABSTRACT FROM AUTHOR]

With the advent of a highly intelligent society, the role of mobile communication represented by the key words ‘anytime, anywhere, and with anybody’ has become increasingly important. This paper describes mainly the mobile stations of the digital communication system in which the frequency-use efficiency is improved significantly, as well as of analog mobile communication system. Also described are the surface acoustic wave devices, especially the low insertion loss filters, which are expected to be the key devices of mobile communication for small and lightweight equipment. [ABSTRACT FROM AUTHOR]

Mason's equivalent circuit is well known as a linear equivalent circuit for acoustic devices. By combining Mason's equivalent circuit with Smith's equivalent circuit of surface acoustic wave devices, it becomes a very effective tool for the physical interpretation of acoustic devices. If such equivalent circuit analysis can also be performed for the nonlinear problem, then comparatively simpler and accurate analysis can be obtained fur almost all types of nonlinear problems. In this paper, equations are formulated to analyze the equivalent circuit of nonlinear-type acoustic devices. At first, Mason's equivalent circuit is extended to the nonlinear region for the basic circuits of a thin bar of length-extensional vibration and a broad plate of thickness-extensional vibrations. Next, this equivalent circuit is used to analyze the thickness-extensional vibration of Z-cut LiNbO3 and second harmonic generation at the resonance point is clarified. Finally, these nonlinear equivalent circuits of length-extensional vibration are applied to determine the nonlinear constants of PZT ceramics end the nonlinear constants of the equivalent circuit are clarified. [ABSTRACT FROM AUTHOR]

This paper considers a plant with structured uncertainties, such as one with a transfer function where the denominator and the numerator, respectively, are represented by a convex combination of two polynomials. A necessary and sufficient condition for the robust stabilization is presented, and the systematic design method for the compensator is shown. Key words: Uncertain system; feedback control; robust stabilization; Hurwitz polynomial; interpolation. [ABSTRACT FROM AUTHOR]

In communication line systems, in general, failure correlation (dependency of communicational line (path) composing a system due to the existence of common-caused failure mode) often occurs and dependent failure correlation between communication lines (paths) must inevitably be considered in many cases. A concrete example is in reliability analysis between communication terminals in communication cable lines linking two central terminals, a characteristic quantity analysis of reliability when γ-fold common-caused failures of neighboring lines occur. Thus, in this paper, we take a parallel redundant system given by common-caused failure (γ) and the number of communication lines (n), etc. [ABSTRACT FROM AUTHOR]

The modular feedback design is the following method. When a control specification in a discrete event system is given by conjunction and disjunction of a finite number of predicates, a feedback is designed for each predicate, and the whole feedback is constructed by product and sum of the component feedbacks. By this design method, the state feedback can easily be reconstructed when the control specification is modified. This paper considers the model proposed by Golaszewski and Ramadge, and we derive a condition under which the control invariance of the component predicates implies the control invariance of their conjunction and disjunction. Moreover, we derive a condition tinder which the unique existence of maximally and minimally permissive feedback for each component predicate implies that for the conjunction and disjunction. Finally, the derived result is applied to control of a manufacturing system. [ABSTRACT FROM AUTHOR]

In the resistance network N, the potential of each vertex determined in reference to one vertex of the input vertex-pair, where a unit current source is placed, can be expressed by using the topological formula as the ratio of the conditional 2-tree conductance product sum to the tree conductance product sum of N. It is a well-known empirical law that the potential of the input vertex (equivalently, the input resistance) does not increase if any two vertices of E are short-circuited. However, no rigorous and simple algebraic proof including the potential variation of the input vertex is available, and such studies on an arbitrary vertex as its generalization have not been carried out. In this paper, the variations of vertex potentials by short-circuiting two vertices of are formulated by using the topological process. If the formula obtained here is used, a necessary and sufficient condition can be provided for increase (or decrease) of any vertex potentials by short-circuiting two vertices of N besides a proof of the forementioned empirical law. In addition, the following can readily be verified. If the potentials of two vertices of N are equal, the potentials of any vertices do not change by short-circuiting the two vertices. Even if a specific vertex potential does not change after short-circuiting two vertices. the potentials of these two vertices are not necessarily equal. [ABSTRACT FROM AUTHOR]

Mobile and portable telephone systems use intermittent signal reception and reduce power consumption during call waiting periods to accomplished longer standby times (longer durable time between battery charging). This is based on shorter turn-on times, system design, and hardware progress. This paper describes schemes for low power consumption technology when the phone is in out-of-service areas, and low power control schemes during call waiting times. © 1998 Scripta Technica, Electron Comm Jpn Pt 2, 81(1): 66–73, 1998 [ABSTRACT FROM AUTHOR]

This paper describes torsional mode quartz crystal resonators of the tuning fork type with stepped vibration bars. A frequency equation and a transcendental equation were derived from the ‘clamped-free’ boundary condition and the stepped portion of the continuity condition, respectively. Because these equations were given as a function of torsional rigidity, the torsional rigidity was derived from the equation of equilibrium. From related equations, it was shown that high or low frequency could be obtained without a change in length. The calculated results were then compared with the measured values so that both results would be in good agreement. [ABSTRACT FROM AUTHOR]

To improve the reliability of an electrical signal transmission through a contact, not only the contact resistance, but also the nonlinear characteristic must be evaluated, especially in the presence of a surface film. This method is effective in the separation of the film resistance and the constriction resistance, and the measurement of film thickness. To investigate the distribution of the oxide film thickness, the system was fully automated to measure the film thickness at various points on a sample surface. The measured properties were the contact resistance and the dc current which is one of the nonlinear components and is needed to cancel the rectification characteristic. To form a contact, copper, platinum and nickel wires were used. This paper demonstrates three-dimensionally and statistically the characteristics at various spots on a plane. [ABSTRACT FROM AUTHOR]

The digital micromirror device (DMD) is a new display device fabricated by the micromachining technique and used in projectors. In this paper, the DMD serves as an ultraviolet exposure system and is tested in applications for projection exposure systems and rapid prototyping. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(7): 56–58, 2000 [ABSTRACT FROM AUTHOR]