We have constructed Bi based layer structured ferroelectric films and their superlattices by a pulsed laser deposition technique. The dielectric constants along c-axis increase with increasing of the number of pseudo-perovskite layers between double Bi2O2 layers. Ferroelectricity appears along the c-axis direction only for the odd number of the perovskite layers owing to the mirror symmetry in a crystal structure. Especially, the Bi2VO5. 5 film shows an atomically flat surface, low dielectric constant of 30 and ferroelectricity of Pr=3 µC/cm2 and Ec=16 kV/cm, respectively. This material is expected to the application for FRAMs.

A new numerical approach for the analysis of electromagnetic scattering from a body moving in an arbitrary direction is described. A time dependent grid generation is applied to solve these problems. We are treating this method for a quasi-stationary field. Some numerical results are compared with the exact ones and excellent agreement between them is obtained.

Sr0. 7Bi2. 3Ta2O9(SBT) films are drawing attention as fatigue-free materials. We prepared an SBT film containing discontinuous crystals in the Bi-layered compound using a misted deposition method. In comparison to films prepared by the spin-on method, leakage current was low and spontaneous polarization is high but saturation performance was low. The low saturation performance seems attributable to the inclusion of discontinuous crystals in the Bi-layered compound, while the low leakage current may be explained by the films smaller, denser particles, which form a film without voids, resulting in higher uniformity. The misted deposition method has advantages of finer grain size and higher uniformity.

Multimedia communications often require intramedia synchronization for video data to prevent potential playout discontinuity while still retaining satisfactory playout throughput. In this paper, we propose a novel intra-video synchronization mechanism, called the Video Smoother, particularly suitable for low-end multimedia applications, such as video conferencing. Generally, the Video Smoother dynamically adopts various playout rates according to the number of frames in the playout buffer in an attempt to compensate for the delay jitter introduced from networks. In essence, if the number of frames in the buffer exceeds a given threshold (TH), the Smoother employs a maximum playout rate. Otherwise, the Smoother employs linearly or exponentially reduced rates to eliminate playout pauses resulting from the emptiness of the playout buffer. To determine optimal THs achieving a minimum of playout discontinuity and a maximum of playout throughput under various bursty traffic, we propose an analytic model assuming incoming traffic following an Interrupted Bernoulli arrival Process (IBP). As a result, optimal THs can be analytically determined resulting in superior playout quality under various arrivals and loads of networks. Finally, we display simulation results which demonstrate that, compared to the playout without intra-video synchronization (instant playout), the Video Smoother achieves superior smooth playout and compatible throughput.

This paper presents experimental results obtained in indoor broad-band transmission experiments using a QPSK-100 Mbps modem in the 37 GHz band. Transmission performance is measured at many antenna locations in an office. The zone coverage, defined points where as the BER was less than 10-7, was derived in order to evaluate the possibility of high-speed transmission. It was found that adjusting the receiving antenna position a few centimeters greatly improves the zone coverage in utilizing millimeter waves. This result indicates the effectiveness in improving zone coverage of space diversity reception with an antenna spacing of several centimeters. Experimental results obtained show that zone coverage of up to 70% in the measured range is achieved by space diversity reception. Thus, the feasibility of 100 Mbps indoor wireless transmission, conventionally thought to be impossible, is experimentally confirmed.

A maximal-ratio-combining (MRC) digital beamformer has been studied to attain open-loop and automatic self-beam steering towards both desired and multipath signals at the same time and diversity combining of the signals, which are made possible by spatial digital signal processing. This paper describes the performance of this beamformer under the multipath signal arrivals with various path delays using numerical simulation, aimed at application to future mobile radios with high spatial utilization efficiency. The results indicate the robustness of the MRC beamformer in a multipath environment. It features multidirectional beam steering when there is small path delay in the multipath signal and gain suppression in multipath signals when their path delay is more than about one symbol. Moreover, improvement in suppression by employing low-sidelobe amplitude distribution is discussed as a means to reduce inter-symbol interference without null-beam steering.

This paper presents a routing methodology and a routing algorithm used in designing Gb/s LSIs with deep-submicron technology. A routing method for controlling wire width and spacing is adopted for net groups classified according to wire length and maximum-allowable-delay constraints. A high-performance router using this method has been developed and can handle variable wire widths, variable spacing, wire shape control, and low-delay routing. For multi-terminal net routing, a modification of variable-cost maze routing (GVMR) is effective for reducing wire capacitance (net length) and decreasing net delay. The methodology described here has been used to design an ATM-switch LSI using 0. 25-µm CMOS/SIMOX technology. The LSI has a throughput of 40 Gb/s (2. 5 Gbps/pin) and an internal clock frequency of 312 MHz.

In this paper, we propose a technique to synthesize a hardware circuit from a protocol specification consisting of several concurrent EFSMs with multi-rendezvous specified among their subsets. In our class, each multi-rendezvous can be specified among more than two EFSMs, and several multi-rendezvous can be specified for different combinations of EFSMs. In the proposed technique, using the information such as current states of EFSMs, input values at external gates and guard expressions, we compose a circuit to evaluate whether each multi-rendezvous can be executed. If several exclusive multi-rendezvous get executable simultaneously for some combinations of EFSMs, we select one of them according to the priority order given in advance. We compose such a circuit as a combinational logic circuit so that it works fast. By applying our technique to Abracadabra protocol specified in LOTOS, it is confirmed that the derived circuit handles multi-rendezvous efficiently.

We have developed a half-duplex spread spectrum-direct sequence (SS-DS) 2. 4 GHz band transceiver (T/R) unit having a smaller size and lower power consumption. A highly efficient elastic SAW convolver with chirp interdigital transducers (IDTs) has been used in the correlation circuit of receiver unit. The code shift keying (CSK) modulation is used in the T/R unit. The size of T/R unit is 90 50 11 mm and the weight is 75 grams. The power consumption of T/R unit is 1. 4 watts. We found that the bit error rate (BER) was less than 10-6 over the range of 0-150 m outdoors and 0-80 m indoors without a digital error detection and correction method. In this case, the data rate was 102 kbps and the transmit RF power was 2. 5 mW/MHz. The electrical characteristics, anti-interference and anti-multipath fading were also evaluated.

In this paper, we give a new approach to the computation of primary decomposition and associated prime components of a zero-dimensional polynomial ideal (f1,f2,. . . ,fn), where fi are multivariate polynomials on Z (the ring of integer). Over the past several years, a considerable number of studies have been made on the computation of primary decomposition of a zero-dimensional polynomial ideal. Many algorithms to compute primary decomposition are proposed. Most of the algorithms recently proposed are based on Groebner basis. However, the computation of Groebner basis can be very expensive to perform. Some computations are even impossible because of the physical limitation of memory in a computer. On the other hand, recent advance in numerical methods such as homotopy method made access to the zeros of a polynomial system relatively easy. Hence, instead of Groebner basis, we use the zeros of a given ideal to compute primary decomposition and associated prime components. More specifically, given a zero-dimensional ideal, we use LLL reduction algorithm by Lenstra et al. to determine the integer coefficients of irreducible polynomials in the ideal. It is shown that primary decomposition and associated prime components of the ideal can be computed, provided the zeros of the ideal are computed with enough accuracy. A numerical experiment is given to show effectiveness of our algorithm.

This paper presents almost rigorous Wiener-Hopf solutions to the plane wave scattering by a conducting finite thin plate. The final field expressions are given in an analytically compact form and the results are accurate as long as the plate width is greater than the wavelength. Numerical examples are given for the near and far field distributions. A criterion is also proposed to estimate under what condition the ray tracing method holds.

Contact recording systems have been studied for future magnetic recording disks with a high recording density. Tribological key technologies for ultra-low spacing and high wear performance are required for the contact systems. Particularly, a liquid lubrication system plays an important roll for reducing a mechanical spacing and improving wear performances. However, a lubrication design concept for contact recording systems is not established. In this study, molecular design of lubricants for contact systems will be discussed from a viewpoint of bouncing and wear behaviors. As a result, a minimum bouncing height of 3 nm and a high wear performance were obtained for ion-etched contact sliders by the optimization of design parameters, i. e. pad design and lubricant material.

A new learning method is proposed to enhance the performances of the fuzzy ARTMAP neural network in the noisy environment. It combines the average learning and slow learning for the weight vectors in the fuzzy ARTMAP. It effectively reduces a category proliferation problem and enhances recognition performance for noisy input patterns.

Coulombs law of friction, in which the coefficient of friction is constant independently of apparent area of contact and applied load, is deduced from the modern adhesion theory. That is, the friction resistance is caused by shearing of solid/solid junctions which are formed through plastic deformation of surface asperities of mating solids. In so-called point contact, on the other hand, different experimental results from Coulombs law have been sometimes reported. In these cases, coefficient of friction is not constant, but reduces with increasing normal load. A weighty interpretation for these facts developed formerly is that Hertzian contact area acts as an effective zone to generate the friction resistance. This interpretation has, however, an important doubt, as the Hertzian contact area is not formed through plastic but through elastic deformation of solids. If the friction resistance is generated in an elastic contact area, the adhesion theory of friction would be shaken at its standing basis. To give an explanation of this inconsistency between the experimental facts reported previously and the adhesion theory of friction, the authors propose a new idea in this paper. The plastic deformation occurs at surface asperities even in Hertzian contact. If the rubbing condition is kept dry, the friction resistance would be generated only at those plastically deformed zone dotted in the elastic contact area, so that Coulombs law is realized. If the rubbing condition is kept wet, the clearance between mating surfaces in the elastic contact zone is filled with any lubricant or contaminant molecules, the friction resistance would be generated through shearing of them within the Hertzian area. In this case, the coefficient of friction would be proportional to(load)-1/3, which is close to observational facts reported previously. An experimental verification made in this study can describe the authors proposal.

A 1. 5 GHz low noise amplifier (LNA) was designed and fabricated by using CMOS technology. The measured associated gain (Ga) of the LNA is 13. 8 dB, the minimum noise figure (NFmin) is 2. 9 dB and the input-referred third-order intercept point (IIP3) is -2. 5 dBm at 1. 5 GHz. The LNA consumes 8. 6 mA from a 3. 0 V supply voltage. These measured results indicate a potential of short channel MOSFETs for high-frequency and low-noise applications.

Time series prediction is very important technology in a wide variety of fields. The actual time series contains both linear and nonlinear properties. The amplitude of the time series to be predicted is usually continuous value. For these reasons, we combine nonlinear and linear predictors in a cascade form. The nonlinear prediction problem is reduced to a pattern classification. A set of the past samples x(n-1),. . . ,x(n-N) is transformed into the output, which is the prediction of the next coming sample x(n). So, we employ a multi-layer neural network with a sigmoidal hidden layer and a single linear output neuron for the nonlinear prediction. It is called a Nonlinear Sub-Predictor (NSP). The NSP is trained by the supervised learning algorithm using the sample x(n) as a target. However, it is rather difficult to generate the continuous amplitude and to predict linear property. So, we employ a linear predictor after the NSP. An FIR filter is used for this purpose, which is called a Linear Sub-Predictor (LSP). The LSP is trained by the supervised learning algorithm using also x(n) as a target. In order to estimate the minimum size of the proposed predictor, we analyze the nonlinearity of the time series of interest. The prediction is equal to mapping a set of past samples to the next coming sample. The multi-layer neural network is good for this kind of pattern mapping. Still, difficult mappings may exist when several sets of very similar patterns are mapped onto very different samples. The degree of difficulty of the mapping is closely related to the nonlinearity. The necessary number of the past samples used for prediction is determined by this nonlinearity. The difficult mapping requires a large number of the past samples. Computer simulations using the sunspot data and the artificially generated discrete amplitude data have demonstrated the efficiency of the proposed predictor and the nonlinearity analysis.

It is well known that the existence of electrically resistive film layers formed on contact surfaces increases contact resistance and it causes a nonlinear relationship between voltage and current observed in a contact layer. Nonlinear distortion voltages can be detected by our sensitive detection system based on the dual frequency method when a thin film exists on the surface. In this study, multilayer films of polyimide (PI) was used as an ideal material of ultra thin film, because of electrically good insulator with simple molecular structure, to study non-linearity through metal-insulator-metal contact. The number of deposited layers between one and twenty one were formed on three types of substrates; (a) evaporated gold on a glass plate, (b) gold plate and (c) evaporated gold on gold plate, to obtain good insulating film. Where each layer of PI film has 0. 4 nanometer thickness. A pin contact was made by pressing a bent gold wire on the PI film. It is concluded that [1]; the second-order distortion voltage increases exponentially as the film thickness increases, [2]; polarity of the surface potential of PI depends on the film thickness, and that I-V characteristic depends on the polarity of the surface potential.

A method has been developed for evaluating the wear durability and adhesion characteristics of ultrathin overcoat films. The relationship between the wear depth and applied load or between the wear depth and number of scanning-scratch cycles is used in AFM nanowear tests. Inherent wear durability, which is independent of adhesion or substrate hardness, can be evaluated from the relationship between wear depth and applied load at relatively low loads, and the adhesion characteristics can be evaluated from the relationship at relatively high loads. Wear durability can be evaluated with a small number of scanning-scratch cycles and adhesion with a large number of cycles.

Gold on connector contacts is superior in environmental resistance. However, pores existing gold film are source to trigger the corrosion reaction between gold and base metal. For examination of the contacts, it has been popular to apply "Salt Spray Test" and "Sulfur Dioxide Test. " There are some differences of the corrosion products between two tests. Main metal forming the product in Salt Spray is Copper, and main metal in Sulfur Dioxide is Nickel. To investigate the reason, we tried to employ an electro-chemical method. As a result, it was found that there was the difference between the respective galvanic cell combinations generated through pores.

The alloy of Ag (40wt%)-Pd(60wt%) has been used in the electrical contacts of electromechanical devices due to its superior contact properties. There is currently, an increasing trend to decrease the size of electromechanical devices. However, it has been difficult to obtain a high contact force and the high restoring force of contacts, and these problems cause contact failures such as high contact resistance. In response to this problem, the alloy is overlaid with an Au layer which is not affected by oxide films. However, when the contacts are subjected to an unacceptable amount of mechanical shock, adhesion of the Au overlay occurs easily. In order to solve these difficulties, it can be proposed to cover the contact surface with high electric conductive oxide films. With this concept, the Au overlay should be unnecessary. In the present study, to reduce the high contact resistance of the Ag-Pd alloy contaminated with an oxide film, very small amounts of Mg and Cr were used in separate doping trials to the alloy. The improvement of contact resistance characteristics is the focus of the present study. Specimens of Ag (40wt%)-Pd(60wt%), Ag-Pd-Mg(0.1, 0.5 and 1.0wt%), and Ag-Pd-Cr(0.1 and 0.5wt%) were oxidized at elevated temperatures to accelerate the process of oxidation, and the growth kinetic law of oxide films grown on the surfaces were evaluated by ellipsometry. The effect of the oxide film on the contact resistance characteristics were then clarified. A marked improvement of the contact resistance caused by the oxide film was found for the Ag-Pd alloy with a Mg doping agent. However, for the Cr doping agent, a low contact resistance was not obtained as same as the Ag-Pd alloy itself.