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.

A 3-dimensional specific thickness profile was fabricated on a thin glass diaphragm lens to reduce aberration at short focal distances for greater dynamic focusing. The deformation of the diaphragm was calculated by stress analysis utilizing the Finite Element Method (FEM). Geometric non linearity is considered in the FEM analysis. The glass diaphragm is 10 mm in diameter and the average thickness is 11 µm. To obtain both a curved shape and an optical surface on the glass diaphragm, the 3-dimensional precision grinding technique was utilized. The processed shape matches the designed one with less than 0.3 µm deviation, and the average surface roughness is 0.005 µm. Optical characteristics of the dynamic focusing lens having a specific thickness profile, were measured by Modulation Transfer Function (MTF) measurement equipment. At a focal distance of 250 mm, the specific thickness diaphragm lens resolution is 10 cycles/mm, whereas, the uniform thickness diaphragm is 4 cycles/mm. Even at other focal distances, the specific thickness diaphragm shows superior optical characteristics in comparison with those of the uniform thickness diaphragm. The 3-dimensional profile diaphragm resolution is 2.5 times finer at a focal distance of 250 mm, thus, being capable of displacement control for variable optic devices. This was achieved by employing semiconductor processing methods in conjunction with precision grinding techniques which are necessary for fabricating micro structures.

GaAs-based micromachining is a very attractive technique for integrating mechanical structures and active optical devices, such as laser diodes and photodiodes. For monolithically integrating mechanical parts onto laser diode wafers, the micromachining technique must be compatible with the laser diode fabrication process. Our micromachining technique features three major processes: epitaxitial growth (MOVPE) for both the structural and sacrificial layers, reactive dry-etching by chlorine for high-aspect, three-dimensional structures, and selective wet-etching by peroxide/ammonium hydroxide solution to release the moving parts. These processes are compatible with laser fabrication, so a cantilever beam structure can be fabricated at the same time as a laser diode structure. Furthermore, a single-crystal epitaxial layer has little residual stress, so precise microstructures can be obtained without significant deformation. We fabricated a microbeam resonator sensor composed of two laser diodes, a photodiode, and a micro-cantilever beam with an area of 400700 µm. The cantilever beam is 3 µm wide, 5 µm high, and either 110µm long for a 200-kHz resonant frequency or 50 µm long for a 1-MHz resonant frequency. The cantilever beam is excited by an intensity-modulated laser beam from an integrated excitation laser diode; the vibration signal is detected by a coupled cavity laser diode and a photodiode.

Micro-tribology is a key technology in micro-machine. Atomic-scale wear and friction fluctuations degrade the performance of micro-machines. New wear-resistant, low friction materials should be useful in reducing micro- and macro-tribological wear and friction fluctuations. Our investigation of the frictional characteristics of polished CVD diamond films by FFM (friction force microscope), AFM (atomic force microscope) and conventional reciprocating tribometer and trial micro processing of diamond produced three main results. First, the friction coefficient of diamond film increases rapidly with decreasing load in the micro-load region. This is partially due to the surface tension of adsorbed water on the surface under high humidity. In the macro-load region also, the friction coefficient increases with decreasing load, but, in this case it is due to elastic deformation. The second result is that diamond film has excellent wear resistance in the micro-load region compared with silicon and diamond-like carbon (DLC) film. Finally, a micro-diamond gear and diamond shaft were fabricated by laser machining and thermo-chemical etching, and then assembled.

The precise phase characteristics of the reflected and transmitted waves are obtained for electromagnetic scattering by inductive discontinuities of finite thickness located in rectangular waveguides. The incident wave is assumed to be the dominant mode, and the modified residue-calculus method is used for numerical analysis. The phase characteristics when the thickness and width of the iris are varied, and characteristics of the reflected and transmitted waves when resonance appears, are discussed. In addition, an X-band experiment is performed and the calculations for both the reflected and transmitted waves are shown to agree well with the experimental values.

For estimating the radiated emission from a metallic enclosure, the authors have developed a numerical computational method which applied inverse analysis. A metallic enclosure containing a loop antenna was set up to be a model source for the numerical analysis. Magnetic fields around the enclosure were measured by measurement systems fabricated in the authors' laboratory. Using the measured magnetic fields, current distributions on the enclosure surface were determined by means of an inverse analysis utilizing the least squares method. From this surface current distribution, the electromagnetic field distributions were estimated by forward analysis on a cylindrical surface 3.0m in radius. The amount of the error in the estimated fields distribution was also discussed.

This paper describes an efficient slew rate enhancement technique especially suitable for an operational amplifier used in an LCD driver IC. This technique employs an input-dependent biasing without directly monitoring an input; instead, monitoring an output of the first stage of the amplifier. This enhancement technique is easily applied to a conventional two-stage operational amplifier and requires only 8 additional transistors to increase slew rates for both rising and falling edges. The bias currents of the first and the second stages are simultaneously controlled by this biasing. Experimental operational amplifiers with and without this enhancement have been fabricated to demonstrate the improvement of slew rate. Slew rates of 12.5V/µsec for the rising edge and 50V/µsec for the falling edge with a 100 pF load capacitance have been achieved by this technique, compared with slew rates of 0.3V/µsec for the rising edge and 5V/µsec for the falling edge in the conventional amplifier.

An efficient algorithm is given for finding all solutions of piecewise-linear resistive circuits containing nonseparable transistor models such as the Gummel-Poon model or the Shichman-Hodges model. The proposed algorithm is simple and can be easily programmed using recursive functions.

This paper describes an advanced rule-embedded neural network (RENN+) that has an extended framework for achieving a very tight integration of learning-based neural networks and rule-bases of existing if-then rules. The RENN+ is effective in pattern recognition with ill-posed conditions. It is basically composed of several component RENNs and an output RENN, which are three-layer back-propagation (BP) networks except for the input layer. Each RENN can be pre-organized by embedding the if-then rules through translation of the rules into logic functions in a disjunctive normal form, and can be trainded to acquire adaptive rules as required. A weight-modification-reduced learning algorithm (WMR) capable of standard regularization is used for the post-training to suppress excessive modification of the weights for the embedded rules. To estimate the effectiveness of the proposed RENN+, it was used for pattern recognition in a radar system for detection of buried pipes. This trial showed that a RENN+ with two component RENNs had good recognition capability, whereas a conventional BP network was ineffective.

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.

In this paper, a design of TCM signals for Middleton's class-A impulsive noise environment is investigated. The error event characteristics under the impulsive noise is investigated, and it is shown that the length of the signal sequence is more important than Euclidean distance between the signal sequences. Following this fact, we introduce the shortest error event path length as a measure of the signal design. In order to make this value large, increasing of states of convolutional codes is employed, and the performance improvement achieved by this method is evaluated. Numerical results show the great improvement of the error performance and conclude that the shortest error event path length is a good measure in the design of TCM signals under impulsive noise environment. Moreover, the capacity of class-A impulsive noise channel is evaluated, and the required signal sets expansion rates to obtain the achievable coding gain is discussed.

We present a design chart and a manufacturing process for mm-wave absorber consisting of two spacers (poly-carbonate) and two-resistive sheets (polyethylene terephthalate deposited with Indium Tin Oxide). The conventional design chart gives us necessary information to make a desirable absorber. Based on the design chart, a multi-layered type absorber was manufactured and it is concluded that a significant absorption level (-20dB) is attained at a wide-frequency range of 46-66GHz.

In this paper, a new off-line handwritten word recognition method based on the explicit modeling of character junctures is presented. A handwritten word is regarded as a sequence of characters and junctures of four types. Hence both characters and junctures are explicitly modeled. A handwriting system employing hidden Markov models as the main statistical framework has been developed based on this scheme. An interconnection network of character and ligature models is constructed to model words of indefinite length. This model can ideally describe any form of hamdwritten words including discretely spaced words, pure cursive words, and unconstrained words of mixed styles. Also presented are efficient encoding and decoding schemes suitable for this model. The system has shown encouraging performance with a standard USPS database.

This paper proposes a constructive linearization method for transistor circuits based on a polynomial representation of nonlinear transfer functions. The nonlinear transfer functions for various configurations have been shown in a polynomial form. Then the results have been applied to several bipolar transistor circuits to exemplify the proposed designing method.

This paper reports on a new dynamic scanning force microscope (SFM), in which the piezoelectric microcantilever is utilized for the lever excitation and displacement sensing. Piezoelectric cantilevers can detect their deflection without external sensing elements and be vibrated with no oscillator outside. The cantilever integrated with the deflection detector and the oscillator changes the conventional construction of a dynamic SFM and expands its range of applicability. The microcantilever used consists of a ZnO layer sandwiched with Au electrodes deposited on a thin beam of thermally grown SiO2. The length, width and thickness of the lever are 125 µm, 50 µm and 3.5 µm, respectively. We have characterized this cantilever by measuring the charge spectrum and the frequency dependence of the admittance. From the charge spectrum the mechanical quality factor measured 300 in free vibration. Typical piezoelectric constant of the ZnO film was estimated approximately as 80% of single-crystal's value. The piezoelectric cantilever can be vibrated by applying the voltage with the frequency near the resonance to the piezoelectric layer. The excited amplitude per unit voltage at the resonance frequency was calculated as about 5 µm/V. The cantilever amplitude can be detected by measuring the current between electrodes, since the admittance depends on the quality factor. We have constructed a dynamic SFM without external oscillator and detector, and successfully obtained the surface images of a sol-gel derived PZT film in the cyclic contact operation mode. The longitudinal resolution of the SFM system was 0.3 nm at a 125 Hz bandwidth.

This paper proposes the overlapped block relaxation Newton method for greatly reducing the number of iterations needed for simulating large scale nonlinear circuits. The circuit is partitioned into subcircuits, i.e., overlapped blocks consisting of core nodes and overlapped nodes. The core nodes form the core circuit for each overlapped block and the overlapped nodes form the overlapped circuit. The Newton-Raphson method is applied to all overlapped blocks independently and the approximation vector for relaxation is determined by node voltages of core nodes. An overlapped circuit is considered to be the representative circuit of the outside circuit for the core circuit. Therefore, the accuracy of the approximation vector for relaxation may be improved and the number of relaxation steps may be greatly reduced. Core nodes are determined automatically by reflecting the circuit structure, then the overlapping level is determined automatically. We show that this method has good performance for simulating large scale circuits, and that it is faster than the nonlinear direct method which is used in standard circuit simulators.

An excitation signal for a synthesis filter plays an important role in producing high quality speech at a low bit rate. This paper presents a new efficient excitation model, Adaptive Density Pulse (ADP) , for low bit-rate speech coding. This ADP is a pulse train whose density (spacing interval) is constant within a subframe but can be varied subframe by subframe. First, the ADP excitation signal is defined. A procedure for finding the optimal ADP excitation is presented. Some results on investigating the effects of the ADP parameters on the synthesized speech quality are discussed. ADP excitation is introduced to the CELP (Code Excited Linear Prediction) coding method to improve speech quality at bit rates around 4 kbps. A CELP coder with an ADP (ADP-CELP) is described. ADP excitation makes it possible for the CELP coder to follow transient portions of speech signals. Also ADP excitation can reduce computational complexity in selecting the best excitation from a codebook, which has been the primary drawback of CELP. The number of multiplications can be reduced to the order of 1/D2 by utilizing the sparseness of ADP excitation, where D is the pulse interval. The authors evaluated the speech quality of a 4 kbps ADP-CELP coder by computer simulation. ADP excitation improved the performance of conventional CELP in segmental SNR.

There have been many investigations of mutual synchronization of oscillators. In this article, N oscillators with the same natural frequencies mutually coupled by one resistor are analyzed. In this system, various synchronization phenomena can be observed because the system tends to minimize the current through the coupling resistor. When the nonlinear characteristics are third-power, we can observe N-phase oscillation, and this system can take (N 1)! phase states. When the nonlinear characteristics are fifth-power, we can observe (N 1),(N 2)3 and 2-phase oscillations as well as N-phase oscillations and we can get much more phase states from this system than that of the system with third-power nonlinear characteristics. Because of their coupling structure and huge number of steady states of the system, our system would be a structural element of cellular neural networks. In this study, it is confirmed that our systems can stably take huge number of phase states by theoretical analysis, computer calculations and circuit experiments.

For symmetric cryptosystems, their transformations should have nonlinear elements to be secure against various attacks. Several nonlinearity criteria have been defined and their properties have been made clear. This paper focuses on, among these criteria, the propagation criterion (PC) and the strict avalanche criterion (SAC), and makes a further investigation of them. It discusses the sets of Boolean functions satisflying the PC of higher degrees, the sets of those satisfying the SAC of higher orders and their relationships. We give a necessary and sufficient condition for an n-input Boolean function to satisfy the PC with respect to a set of all but one or two elements in {0,1}n{(0,...,0)}. From this condition, it follows that, for every even n 2, an n-input Boolean function satisfies the PC of degree n 1 if and only if it satisfies the PC of degree n. We also show a method that constructs, for any odd n 3, n-input Boolean functions that satisfy the PC with respect to a set of all but one elements in {0,1}n{(0,...,0)}. This method is a generalized version of a previous one. Concerned with the SAC of higher orders, it is shown that the previously proved upper bound of the nonlinear order of Boolean functions satisfying the criterion is tight. The relationships are discussed between the set of n-input Boolean functions satisfying the PC and the sets of those satisfying the SAC.

A systematic theory of the optimum multi-path interpolation using parallel filter banks is presented with respect to a family of n-dimensional signals which are not necessarily band-limited. In the first phase, we present the optimum spacelimited interpolation functions minimizing simultaneously the wide variety of measures of error defined independently in each separate range in the space variable domain, such as 8 8 pixels, for example. Although the quantization of the decimated sample values in each path is contained in this discussion, the resultant interpolation functions possess the optimum property stated above. In the second phase, we will consider the optimum approximation such that no restriction is imposed on the supports of interpolation functions. The Fourier transforms of the interpolation functions can be obtained as the solutions of the finite number of linear equations. For a family of signals not being band-limited, in general, this approximation satisfies beautiful orthogonal relation and minimizes various measures of error simultaneously including many types of measures of error defined in the frequency domain. These results can be extended to the discrete signal processing. In this case, when the rate of the decimation is in the state of critical-sampling or over-sampling and the analysis filters satisfy the condition of paraunitary, the results in the first phase are classified as follows: (1) If the supports of the interpolation functions are narrow and the approximation error necessarily exists, the presented interpolation functions realize the optimum approximation in the first phase. (2) If these supports become wide, in due course, the presented approximation satisfies perfect reconstruction at the given discrete points and realizes the optimum approximation given in the first phase at the intermediate points of the initial discrete points. (3) If the supports become wider, the statements in (2) are still valid but the measure of the approximation error in the first phase at the intermediate points becomes smaller. (4) Finally, those interpolation functions approach to the results in the second phase without destroying the property of perfect reconstruction at the initial discrete points.