Thermal stability of reinforced Nb3Sn composite superconductor under cryocooled conditions

Several types of reinforced Nb₃Sn wires have been developed to prevent reduction of superconducting properties by applying a strong electromagnetic force. To fabricate a cryocooled magnet using those reinforced wires, we experimentally measured the minimum quench energy (MQE) under cryocooled conditions of some reinforced Nb₃Sn wires. As a result, it became clear that thermal stability expressed as MQE was controlled by the temperature margin between the temperature of the operating condition and the transition temperature from superconductivity to normal. Using the FEM analysis, it was realized that the cause of the decline in thermal stability for the reinforced wires was the low thermal conductivity of the reinforced materials.     

A high-speed vector-controlled spindle motor drive with closedtransition between with encoder control and without encoder control

A 40000-r/min vector-controlled induction motor drive is introduced. The vector control of induction motors has been widely accepted in spindle drives of machine tools where they replace conventional DC motors because of the low maintenance requirements. Another important feature of the AC spindle drive is its high-speed capability. The magnetic encoder is most widely used as the speed detector because it is suited for use in an adverse environment. However, the magnetic encoder with high resolution and a high S/N ratio loses the output pulses at extremely high speed. In the drive system introduced, the conventional vector control is used in the low-speed range, and the vector control without the encoder is used in the high-speed range. Close transition between two modes is made without interrupting the operation     

Development of 170 GHz/500 kW gyrotron

A development of 170GHz/500kW level gyrotron was carried out as R&D work of ITER. The oscillation mode is TE_31,8. In a short pulse experiment, the maximum power of 750kW was achieved at 85kV/40A. The efficiency was 22%. In the depressed collector operation, 500kW/36%/50ms was obtained. The maximum efficiency of 40% was obtained at P_RF=470kW whereas the power decrease by the electron trapping was observed. Pulse extension was done up to 10s at P_RF=170kW with the depressed collector operation. The power was limited by the temperature increase of the output window.     

A case of aneurysm of the descending thoracic aorta associated with Beh?et's disease]

A 66-year-old male with Beh?et's disease admitted again with hemoptysis. He underwent the resection and direct closure of descending aortic aneurysm 3 years ago, followed without the use of steroid. Chest CT scanning demonstrated a recurrent aneurysm of the descending aorta which was could not be detected on the previous CT only 23 days before. In the current operation, we performed resection, direct closure and wrapping of the aneurysm. The pathological examination showed a true aneurysm of Beh?et's disease. The patient is free from recurrence for 17 months since the operation under steroid therapy.     

A new voltage control equipment using fuzzy inference

Power system control equipment needs higher sensitivity and operational reliability. Advanced voltage control equipment is needed for reducing the frequency of tap changes and improving the characteristics (the relationship between the actual voltage and reference voltage) of the voltage to meet today's power system requirements. However, these objectives are in a trade-off relationship. Studies of voltage control derived from a knowledge base suitable for electric power systems can satisfy these objectives using fuzzy inference. Compared with corresponding conventional equipment, the new equipment improved the deviation of 30 min average voltage of 30 percent. This paper describes the design concept of new voltage control equipment using fuzzy inference. In addition, field test results are described along with rules of fuzzy inference, membership functions, and the deviation of 30 min average voltage through detailed simulation.     

Direct Spectroscopic Determination of Europium(Ⅱ) Concentration During Europium(Ⅲ) Electro-Reduction in Hydrochloric Acid Medium

UV-Vis spectroscopy was used to directly determine the concentration of Eu(Ⅱ) during electroreduction of Eu(Ⅲ) in hydrochloric acid medium. Electroreduction was carried out in a flow type electrolyzer with glassy carbon cathode at the constant potential of -800 mV vs. Ag/AgCl. The effects of oxygen and concentration of hydrochloric acid on the system were investigated. For 0.01 mol·L-1 hydrochloric acid, calibration curves for Eu(Ⅱ) absorption bands at 248 and 320 nm were constructed. Molar absorption coefficients were estimated to be 2016 and 648 L·mol-1·cm-1, respectively. The absorbance strongly decreased with decrease in pH of the solution, whereas concentration of chloride had only a negligible effect.     

An empirical approach for structure-based prediction of carbohydrate-binding sites on proteins

A computer program system was developed to predict carbohydrate-bindingsites on three-dimensional (3D) protein structures. The programssearch for binding sites by referring to the empirical rulesderived from the known 3D structures of carbohydrate–proteincomplexes. A total of 80 non-redundant carbohydrate–proteincomplex structures were selected from the Protein Data Bankfor the empirical rule construction. The performance of theprediction system was tested on 50 known complex structuresto determine whether the system could detect the known bindingsites. The known monosaccharide-binding sites were detectedamong the best three predictions in 59% of the cases, whichcovered 69% of the polysaccharide-binding sites in the targetproteins, when the performance was evaluated by the overlapbetween residue patches of predicted and known binding sites. Received April 24, 2003; revised June 2, 2003; accepted June 10, 2003.     

Physicochemical properties of rare earth perovskite oxides used as gas sensor material

The change of the conductivity in the rare earth perovskite oxide took place after the chemisorption of flammable gases. The sensitivity for methanol was highest. From the conductivity change of these perovskite oxides after the injection of methanol, the energy needed to promote an electron from a conducting to a nonconducting state, E=E _c-E _t, could be derived from the equation=A ₀ exp (–E/kT). LnCoO₃ had the smallest E and H (metal-O), which is the binding energy of oxygen coordinating to the metal ions, but exhibited the highest activity for gas sensing. The gas sensing mechanism was also considered.