In this paper, an electrostatic actuator with electret is proposed. Electrets are the electrical equivalent of magnets. They are dielectric's carrying a non equilibrium permanent space charge or polarization distribution. This distribution can create either an external electric field or internal properties such as piezo or pyroelectricity. In the first case it is possible to make new types of electrostatic actuators by the external electric field. An electrostatic relay with electret is fabricated to demonstrate the possibility of an electrostatic actuator with electret. The size of relay is 5.2 mm11.5 mm. Its amature beam is 50 µm thick, 2.9 mm wide, 6.3 mm long, and acts as a moving electrode. Facing it, the stationary electrode is 20 µm away from the moving electrode. On the stationary electrode, new type of electret made from SiO2 is deposited. We have succeeded in making the armature operate at low applied voltage 20 V. On the same structure without electret, we need more than 120 V to make the same armature operation. We have also succeeded in making the armature latching.

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

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

This paper describes the method of applying the integral form of Maxwell's equations to the transmission-line network used in the spatial network method for the modeling of curved conductor surfaces. The techniques of dealing with the transmission-line network near cylindrical conductor surface are explained in detail. To compare exact solutions with computed values, a cylindrical cavity resonator is analysed. The resonant frequencies and unloaded Q's for the computed three modes are obtained with the error of about 1%. Moreover, applying this treatment to the waveguide with magnetron anodeshape cross section, a cutoff-constant is computed successfully. It is found that the treatment proposed in this paper can be used as the method for modeling of curved conductor surface in the spatial network method. It is also considered that this treatment can be extend to TLM method.

Long-wavelength 1.3 µm GaInAsP/InP vertical cavity surface-emitting lasers (VCSELs) have been demonstrated in an array configuration. With the strong current confinement by a buried heterostructure and the efficient optical feedback by a dielectric cavity, five VCSEL elements in a 24 array operated at room temperature with 5 mW total power output and wavelength error within 5%. The stacked planar optics including the VCSEL array is a promising optical transmitter in ultra large scale parallel optical communication systems.

The objective of this study is to realize a manipulator of 0.5 mm in outside diameter as a part of 'research and development of micro machine technology.' This manipulator is intended as a part of a working robot to fix or observe the inside wall of a small pipe. One of the important problems of this research is to establish a processing method of a tubular small structure. MIM, metal injection molding, has been adopted to fabricate such a small structure. As a processing method to machine small molds for MIM, finish processing with surface roughness of Rmax 0.1 µm has been under our research applying 'vibrational processing technology,' which was developed on our own. This paper presents the results of 'vibrational processing technology' surface finishing of molds for metal injection.

Results of an empirical investigation of the shielding properties of a small pre-fabricated reinforced concrete building are presented. The electric field attenuation was measured in the frequency range of approximately 20kHz to 500MHz. The experiments were performed in collaboration with the Italian National Board of Post an Telecommunications (ISPT). An equivalent stick model has been analyzed in frequency domain by numerically solving a set of electric field integral equations. The influence of the real reinforcement mesh (dimensions, spatial disposition, electrical parameters) on the attenuation of the electric field has been investigated. A comparison between computed and measured results is presented.

It has become very important to study the lightning surges that were induced in subscriber telecommunication equipment because of the increase of susceptible circuits to the over voltage. The test generator is desire to be developed evaluating the resistibility of equipments against lightning surges. This paper proposes a new lightning-test method for subscriber telecommunication equipment. The waveform of the test generator simulates that of the induced lightning surge voltage caused by a nearby return stroke. The output impedance of the surge generator is determined to match the common-mode impedance of telecommunication lines. The damaged condition of circuit parts and the trouble occurrence rate estimated by using this method agree well with actual observations.

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.

The improved point-matching method with Mathieu function expansion for the accurate analysis of the W-type elliptical fiber with layers of any ellipticity is proposed. Results of our method are reliable, because we expand the electromagnetic fields by a sum of the complete set of wave functions in each layer of the fiber. Numerical results are presented for the highly-birefringent fibers with a hollow layer outside an elliptical core. It is found that such fibers can realize the large value of the modal birefringence as well as they can be suitable for the single-mode and single-polarization transmission. From the convergence tests, it is confirmed that the relative error of the modal birefringence is less than 0.01%. The comparison of our results with those by previously reported method is presented. The proposed method can be extended for analysis of the elliptical-core fibers with hollow pits and electromagnetic scattering by targets of the complex elliptical geometry.

A novel total harmonic distortion (THD) measuring technique is proposed. A modified Volterra series using harmonics in place of powers of the sinusoidal input is used to identify the nonlinear models of the source and the device under test (DUT). The least-mean square (LMS) adaptive algorithm is applied for identification. While maintaining comparable speed and accuracy this technique provides a more flexible test procedure than conventional methods, in terms of the frequency resolution, the number of samples, and the sampling rate. It outperforms conventional methods when there is a bin energy leakage, which occurs in a non-coherent system. In addition, it is real-time computing while other conventional methods post process blocks of data. Simulation results collaborate the analytical results.

A new device consisting of an optical pulse generation section and pulse coding section monolithically integrated on a single-chip has been developed. The pulse generation section consists of a multiple quantum well (MQW) electroabsorption modulator integrated with an MQW DFB laser. The modulator operates at large-signal modulation and low voltage (from 2 to 3-V DC bias with a 3.2-V peak-to-peak RF signal). The second modulator is operated independently as a pulse encoder. An approximately transform-limited optical pulse train, whose full width at half maximum (FWHM) in the time domain is less than 17-ps and spectral FWHM is 28-GHz, is obtained with a repetition frequency of 10-GHz. Compressive strain is introduced in both InGaAsP quantum wells in order to obtain efficient device characteristics. These include a low threshold current (18-mA) for the laser, and low driving voltage (30-dB for 3-V swing) and high-speed operation (over 12-GHz for a 3-dB bandwidth) for the modulators. Demonstrations show that this new device generates short optical pulses encoded by a pseudo-random signal at a rate of 10 Gbit/s. This is the first time 10 Gbit/s modulation has been achieved with a multi-section electroabsorption modulator/DFB laser integrated light source. This monolithic device is expected to be applied to optical soliton transmitters.

This paper proposes a multi-fisheye distortion method which can show a large-scale telecommunication network in a single window on the display of a workstation or personal computer. This distortion method has three advantages over the conventional single-fisheye distortion method. First, the focus area is magnified smoothly by the fisheye distortion method, and the peripheral area coordinates are calculated linearly to avoid unnecessary distortion. Second, multiple focus areas are magnified smoothly by using an average of the coordinates calculated for the individual focuses. Third, the scale of unnecessary areas is reduced to provide sufficient space for magnification. The effectiveness of this method is demonstrated by applying to the display of large-scale networks. The effect of the resulting network map distortion on the user is tested by a subjective evaluation experiment.

This paper proposes a new approach to the management of large-scale communication networks. To manage large-scale communication networks effectively, it is essential to get a bird's-eye view of them when they are in their normal conditions. When an indication of faulty state is detected, the focus of the management is narrowed down to the faulty network elements until the appropriate granularity is reached. This management scheme is called multilevel network management in this paper, and it first explains the significance of this scheme for large-scale communication networks and presents some ideas on implementing this management scheme. It then proposes that system identification be used in multilevel network management. The system identification is used to measure transmission delays between two arbitrarily selected nodes in the networks, and multilevel network management is achieved by selecting those two nodes appropriately in accordance with the levels to be managed. Finally, it is demonstrated by computation simulation results that the proposed method is suitable for multilevel network management.

Feasibility of 20 Gbit/s single channel transoceanic soliton transmission systems with a simple EDFA repeaters configuration has been studied. Both a simple and versatile soliton pulse generator and a polarization insensitive optical demultiplexer, which can provide a almost square shape optical gate with duration of full bit time period, have been proposed and demonstrated by using sinusoidally modulated electroabsorption modulators. The optical time-division multiplexing/demultiplexing scheme using the optical demultiplexer results in drastic improvement of bit error rate characteristics. We have experimentally confirmed that the use of alternating-amplitude solitons is an efficient way to mitigate not only soliton-soliton interaction but also Gordon-Haus timing jitter constraints in multi-ten Gbit/s soliton transmission. Timing jitter reduction using relatively wide band optical filter bas been investigated in 20 Gbit/s loop experiments and single-carrier, single-polarization 20 Gbit/s soliton data transmission over 11500 km with bit error rate of below 10-9 has been experimentally demonstrated, using the modulator-based soliton source, the optical demultiplexer, the alternation-amplitude solitons, and wide-band optical filters. Obtained 230 Tbit/skm transmission capacity shows the feasibility of 20 Gbit/s single channel soliton transoceanic systems using fully practical technologies.

The polarization dependence of femtosecond soliton-soliton interactions is investigated in detail. When the polarization direction of two solitons is orthogonal, the soliton interaction can be reduced in comparison to that for parallel polarization. The soliton self-frequency shift (SSFS) is still observed even in the orthogonal condition, but the quantity of the SSFS is much smaller than in the parallel condition. A stronger soliton interaction is observed between two solitons in an in-phase condition, than in an out-of-phase condition. The largest SSFS occurs in-phase with parallel polarization. The polarization dependence of femtosecond soliton interaction in a distributed erbium-doped fiber amplifier (DEDFA) is also investigated. It is shown that when the optical gain of the DEDFA is given adiabatically, the input pulse separation at which the first soliton occurs is less with orthogonal polarization. This is because the soliton pulse width is reduced due to the adiabatic soliton narrowing caused by the optical amplification.

Ultrashort pulsed-beam propagation in a Kerr-type bulk medium is studied theoretically through classical and quantum field solutions of a higher-order nonlinear Schrödinger equation, which is valid for transversely localized femtosecond pulses in an anomalous dispersion regime. Quantum-mechanical stability analysis via a Hartree approximation to interacting bosons shows that within a certain range of a parameter the solitary wave could be stabilized even in the three-dimensional transverse space-time. This feature admits of an exotic route to multidimensional solitons.

This paper discusses sign word segmentation methods and extraction of motion features for sign language recognition. Because Japanese sign language grammar has not yet been systematized and because sign language does not have prepositions, it is more difficult to use grammar and meaning information in sign language recognition than in speech recognition. Segmentation significantly improves recognition efficiency, so we propose a method of dividing sign language based on rests and on the envelope and minimum of motion speed. The sign unit corresponding to a sign word is detected based on the divided position using such features as the change of hand shape. Experiments confirmed the validity of word segmentation of sign language based on the temporal structure of motion.

Most current management systems employ graphic-user-interface displays to visualize the networks being managed. Some networks are so large that it is difficult to display all network elements in a single window alone, and therefore, the hierarchical multi-window style presentation is commonly used. This form of presentation has disadvantages, however, including the fact that window manipulations are complex. Our approach (bifocal network visualization) is able to display both the context and any detail of a network within a single window, and overcomes the disadvantages of hierarchical multi-window presentation. We implemented this bifocal network visualization on a workstation using a frame buffer memory called DUALQUEST that is able to generate images in real-time and is simple to operate. This paper describes bifocal network visualization and its implementation. Furthermore, we present an experiment to compare our interface with conventional hierarchical multi-window presentation.

We exactly determine the number of negations needed to compute the parity functions and the complement of the parity functions. We show that with k NOT gates, parity can be computed on at most 2k+11 variables, and parity complement on at most 2k+12 variables. The two bounds are shown to be tight.