Transient analysis of an advanced static var compensator using quad-series voltage-source PAM inverters

This paper deals with an advanced static Var compensator (ASVC) using quad-series voltage-source PAM inverters. The ASVC consists of four three-phase voltage-source inverters with a common dc capacitor and four three-phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square-wave voltage, while the synthesized output voltage of the ASVC has a 24-step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses. In this paper, transient analysis is performed with the focus on the response of reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small-rated laboratory model of 10 kVA are also shown to verify analytical results based on the p-q transformation. The analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains.     

Study on purple pigmentation in five cases with purple urine bag syndrome

We reported five patients with purple urine bag syndrome (PUBS). Four patients had indicanuria, and, in three of them, purple pigmentation was reproduced by inoculating urinary isolates, in the broth with indoxyl sulfate. Klebsiella pneumoniae, Pseudomonas aeruginosa and Enterococcus avium were considered to produce the purple pigment in three patients. However, attempts to reproduce the purple pigment failed in two patients, and one of them did not have indicanuria. These results suggest that indicanuria is not necessarily required for the development of PUBS.     

Cloning of a novel signal-transducing adaptor molecule containing an SH3 domain and ITAM

We molecularly cloned a cDNA coding for a novel phosphotyrosine molecule with a 70 kDa molecular mass, named STAM (signal transducing adaptor molecule), which is tyrosine-phosphorylated rapidly after stimulation with various cytokines such as IL-2, IL-3, IL-4, IL-7, GM-CSF, EGF and PDGF. STAM contains an SH3 (Src-homology 3) domain and the ITAM (immunoreceptor tyrosine-based activation motif), suggesting that STAM acts as an adaptor molecule involved in signal transducing pathways from the cytokine receptors.     

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.     

Development of enhanced depth-resolution technique for shallow dopant profiles

A rapid shrinkage in the minimum feature size of integrated circuits requires analysis of dopants in their shallow source–drain and their extensions with an enhanced depth resolution. Rutherford backscattering spectroscopy (RBS) combining a medium-energy He ion beam with a detector of improved energy resolution should meet the requirement of a depth resolution better than 5 nm at a depth of 10–20 nm in the next 10 years. A toroidal electrostatic analyzer of 4×10⁻³ energy resolution has been used to detect the scattered ions of a medium-energy He ion beam. Five keV As⁺ implanted Si or SiO₂ samples were measured. Depth profiling results using the above technique are compared with those of glancing-angle RBS by MeV energy He ions. Limitations in the energy resolution due to various energy-spread contributions have been clarified.     

Robust stabilization of a magnetic suspension system using H∞ Control Theory

This paper presents the robust control design of a magnetic suspension system for a flexible beam which is a simplified model of an elastic rotor in a magnetic bearing system. To stabilize this magnetic suspension system which is unstable in nature, the H^infin; control theory is applied for a design of the control system. To apply the H^infin; control theory, a statespace model of an augmented plant with frequency-weighting functions is constructed. This augmented plant has two inputs which are the exogenous inputs and the control inputs, and two outputs which are the sensor outputs and the regulated outputs. Here we consider the mixed sensitivity problem. The H^infin; controller is implemented by a digital controller which is able to execute the computations very quickly. For the evaluation of the control performance, several experiments are made. The robustness of the closed-loop system is confirmed by the experimental results. The result of this study is useful for the control design of a magnetic bearing system.     

Narrow spectral linewidth characteristics of monolithic integrated-passive-cavity InGaAsP/InP semiconductor lasers

The spectral linewidth of 1.3 ?m monolithic integrated-passive-cavity (IPC) semiconductor laser is measured by a delayed self-heterodyne technique. It is found that the line-width is narrowed when longitudinal submode is suppressed. The narrowest linewidth obtained so far is 900 kHz at 6 mW output power.     

Skew simulation of a paper transferred by rubber rollers in printers

A skew of a paper transferred by rubber rollers in printers is simulated by FEM software. Effects of an imbalance of preload, an imbalance distribution of coefficient of friction and a front tension on the paper skew are investigated and how to determine the skew direction are shown. A simulation model is composed of a feed roller, a preload roller and a paper. The feed roller is rotated forcibly by a certain degree at every calculation step and a deformation, displacement and strain of the paper and rollers are calculated. A series of calculation results is shown as a motion simulation. The results show that the paper skews to the smaller preload side, to the smaller coefficient of friction side, or to the opposite side of the front tension. Further, effects of a skew prevention guide plate is simulated.