A new lateral MOS-gated thyristor with controlling base-current

A new lateral MOS-gated thyristor, called the Base-Current-Controlled Thyristor, is described. This device is designed so that most holes at the on-stage reach the P base through the floating P⁺ region adjacent to the P base and the on-state MOSFET. At the turn-off stage, the interruption of the hole current to the P base due to switching off the above MOSFET occurs simultaneously with the conventional turn-off operation. The concept of this device is verified experimentally by using the fabricated lateral device with the external MOSFET. This device exhibits a better trade-off relation between the on-state voltage and the turn-off time compared uith the conventional MOS-gated thyristor     

A stacking mechanism for setting bills upright in an automated teller machine

 To deal with circulated bills in various conditions regarding size, shape, and rigidity, we have developed a new bill-stacking cassette that can accept and re-dispense various-sized bills. This cassette stacks the bills upright by using deforming guides and sheet rollers under our newly developed “phase control”. It was experimentally verified by stacking tests that the cassette can handle bills in various conditions; thus, we conclude that the new cassette is practical for stacking circulated bills and re-dispensing them securely. Received: 14 August 2001/Accepted: 11 December 2001     

New approach to environmentally benign epoxidation: the solid-phase-system using urea–H2O2 and recyclable dodecatungstate on apatite

On the basis of new concept using a solid disperse phase we have developed an efficient catalytic solid-phase-system for epoxidations of alkenes using urea–hydrogen peroxide (urea–H₂O₂) complex and cetylpyridinium dodecatungstate ((CetylPy)₁₀[H₂W₁₂O₄₂]) catalyst on fluorapatite (FAp). The recovered solid catalyst phase was reused to keep the catalytic activity after several times. In the conceptual idea it is a key point that in situ solid-phase-activation of the catalyst with urea–H₂O₂ proceeds to form microcrystals of the active species dispersed on the solid phase. The dispersion of the catalyst on FAp in the case of tungstic acid (H₂WO₄) was suggested by EPMA analysis. We proposed the peroxo type of species keeping the parent polyoxometalate framework as novel active species from FT-IR spectroscopic studies. FAp phase plays important roles of dispersing the active species on its surface to have high catalytic activity and of stabilizing the active species to lead to high reusability.     

Analytical evaluation technique of self-phase-modulation effect onthe performance of cascaded optical amplifier systems

We propose an approximate analytical evaluation technique of self-phase-modulation (SPM) in cascaded optical amplifier systems. The effect of SPM on optical pulse distortion is represented by the increase in the α-parameter of the transmitter. The waveform distortion is approximated by assuming that the pulse is transmitted over a dispersive fiber without nonlinearity. This technique greatly reduces the calculation time, and is especially useful in designing cascaded amplifier systems, evaluating theoretical maximum transmission distance     

Integrated optical devices of InGaAsP/InP heterojunction phototransistor and inner stripe light-emitting diode

New integrated optical devices combining an InGaAsP/InP HPT and an inner-stripe LED are proposed and their fabrication processes are described. The device functions of light amplification, optical bistability, and optical switching are demonstrated in the 1-μm wavelength region.     

Investigation of the nucleation and growth mechanisms of nanocrystalline diamond/amorphous carbon nanocomposite films

Nucleation and growth, but especially the development of the morphology of nanocrystalline diamond/amorphous carbon (NCD/a-C) nanocomposite films have been investigated by systematic variation of three important parameters, namely the deposition time, the growth rate, and the substrate pre-treatment used to enhance the nucleation density. The films have been characterized, among others, by scanning electron microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy. It is shown that, by successive addition of ultradispersive diamond powder to the suspension of nanocrystalline diamond powder in n-pentane used for the ultrasonic pre-treatment, the nucleation density can be enhanced by two orders of magnitude from 1 · 10⁸ cm^− 2 to > 1 · 10¹⁰ cm^− 2. This reduces the thickness required to achieve closed films from 1 µm to 100 nm. However, once coalescence of the individual nodules emerging from the nucleation sites has taken place the films loose “memory” of the nucleation step and start to develop the typical NCD morphology consisting of larger features with diameters of some hundreds of nm which are in turn composed of much smaller features. Irrespective of the feature size and of the parameters used, the films of this investigation possess AFM rms roughnesses of 9–13 nm, indicating that rms values are not sufficient to characterize NCD surfaces.     

Accelerator Analysis of Tributyltin Adsorbed onto the Surface of a Tributyltin Resistant Marine Pseudoalteromonas sp. Cell

Tributyltin (TBT) released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship’s ballast water. The isolate (10^{9.3 ± 0.2} colony-forming units mL⁻¹) adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 10^8.2. The value was reduced to about one-fifth when the lysozyme-treated cells were used. The surface of ethanol treated cells became rough, but the capacity of TBT adsorption was the same as that for native cells. These results indicate that the function of the cell surface, rather than that structure, plays an important role to the adsorption of TBT. The adsorption state of TBT seems to be multi-layer when the number of more than 10^6.8 TBT molecules is adsorbed by a single cell.     

Flexible generation mix under multi objectives and uncertainties

Criteria for evaluating flexibility of a generation mix are presented, and an efficient computational algorithm for determining a flexible generation mix considering uncertainties in the power system expansion planning is developed. The flexible generation mix problem is formulated as a multiobjective optimization problem and solved by the dynamic programming technique in which type of generation plant is selected as a stage and generation capacity is selected as a state. The proposed method can treat easily not only the uncertainties but also many constraints of generation planning such as integer solutions of generation capacities, reliability constraints, and so on. The effectiveness and feasibility of the proposed method are demonstrated on a typical power system model