Electrical conductivity of a sintered pellet of octalithium zirconate

The conductivity of a sintered pellet of Li₈ZrO₆ was measured in dry or wet argon atmosphere by the two-terminal technique with an AC Wheatstone bridge in the temperature range 350–1050 K. The temperature dependence of conductivity multiplied by temperature $\text{(σT)}$ of Li₈ZrO₆ in a dry environment had two transition points at 426 and 833 K. The activation energies of conductivity in high, middle and low temperature regions were 103.2, 52.1 and 37.4 kJ/mol, respectively. The activation energies of conductivity agreed well with those obtained by temperature dependence of spin-lattice relaxation time $\text{T}{}_1$ of ⁷Li with pulsed nuclear magnetic resonance.     

Void reactivity evaluation by modified conversion ratio measurements in LWR critical experiments

We have developed a void reactivity evaluation method by using modified conversion ratio measurements in a light water reactor (LWR) critical lattice. Assembly-wise void reactivity is evaluated from the “finite neutron multiplication factor”, k*, deduced from the modified conversion ratio of each fuel rod. The distributions of modified conversion ratio and k* on a reduced-moderation LWR lattice, for which the improvement of negative void reactivity is a serious issue, were measured. Measured values were analyzed with a continuous-energy Monte Carlo method. The measurements and analyses agreed within the measurement uncertainty.

The developed method is useful for validating the nuclear design methodology concerning void reactivity.     

Prenatal management of fetal cardiac tumors. Two case reports

Although primary cardiac tumors are extremely rare, their prenatal and neonatal management is very important because fetal arrhythmia is a frequent complication and such tumors may be the only manifestation of tuberous sclerosis. We present 2 cases of fetal cardiac tumor in which cardiac function was assessed by color Doppler ultrasonography. In both cases, there was no evidence of tuberous sclerosis or cardiac failure and tumor regression was noted 8 months after birth. Ultrasonographic examination of fetal cardiac function was useful in the management of these tumors.     

New xenon excimer lamps excited by quasi-CW jet discharges

New xenon excimer lamps in vacuum ultraviolet (VUV) have been developed in quasi-CW jet discharges. Quantitative characteristics of xenon clusters produced with two different kinds of nozzles were studied to verify the xenon excimer formation mechanisms in jet discharges. Experimental results strongly indicate the xenon excimer emission at 174 mn as a result of the direct excitation of the xenon clusters. Output powers and pulse widths of the lamps were thus controlled by changing cluster formation parameters. The maximum output power of 1.5 W with an efficiency of 3.0% was obtained at 174 nm when the conical nozzle was used. The VUV emission lasted 5 ms (FWHM)     

DCT/IDCT processor for HDTV developed with dsp silicon compiler

This article presents a discrete cosine transform (DCT) processor for high definition television (HDTV) by using an extended version of DSP Silicon Compiler. The extension is mainly concerned with module generation functions. A matrix-vector product module composed of multiply-accumulators (MACs) is newly added to the silicon compiler. The compiler accomplishes placement of leaf-cells and routing between the cells, referring to a prototype layout for the MAC. The prototype, which consists of a Booth multiplier and a carry look ahead adder, is carefully designed to attain high operation speed. The processor developed by the silicon compiler carries out 8×8 DCT and its inverse transform (IDCT). In order to evaluate the newly extended functions in the compiler, the architecture employed for the processor is based on the matrix-vector product method. By using DSP Silicon Compiler and 0.8 µm triple metal CMOS technology, the DCT processor is easily implemented with error-free environment and achieves a 50MHz data rate, which meets Japanese HDTV base line signal processing. The chip is implemented on a 12.80×12.57mm ² area.     

Demodulation scheme for polarimetric optical fibre sensors usingderivative technique

A demodulation method for polarimetric optical fibre sensors is described and demonstrated. Two signals with a π/2 phase difference are generated from the sensor output signal and its first derivative with respect to the phase. This method does not require strict modulation conditions for the laser source     

Improvement of the beam lifetime by applying an rf electric kick field in the compact storage ring

The lifetime of the stored electron beam in the compact storage ring AURORA is governed by the Touchek effect. It has been shown that it is appreciably increased by applying a vertical rf kick field to the electron beam without giving harmful effect to the beam stability. Interferometric measurement of the radiation beam profile showed an increase in the beam size, indicating the reduction of the Touchek effect. Application of the field with increase in power has induced collective excitation of the betatron oscillation.     

The simultaneous removal of calcium and chloride ions from calcium chloride solution using magnesium-aluminum oxide

We investigated the removal of Ca(2+) and Cl(-) from CaCl(2) solution at 20-60 degrees C, using magnesium-aluminum oxide, Mg(0.80)Al(0.20)O(1.10), prepared by the thermal decomposition of a hydrotalcite-like compound, Mg(0.80)Al(0.20)(OH)(2)(CO(3))(0.10).0.78 H(2)O. The degree of Ca(2+) and Cl(-) removal from the solution increased with increasing initial CaCl(2) concentration, temperature, and quantity of Mg(0.80)Al(0.20)O(1.10) added. When Mg(0.80)Al(0.20)O(1.10) was added to 0.25 M CaCl(2) solution in a Mg(0.80)Al(0.20)O(1.10)/CaCl(2) molar ratio of 20, the degree of Ca(2+) and Cl(-) removal from the solution at 60 degrees C after 0.5 h was 93.0% and 98.2%, respectively. These results reveal that Mg(0.80)Al(0.20)O(1.10) has the capacity to remove Ca(2+) and Cl(-) simultaneously from aqueous solution.     

中碳调质钢焊接区氢致裂纹行为的直接观察

本研究对铬镍系中碳调质钢(SNC631)的高温充氢试件及焊接试件中,氢致裂纹的宏观与微观行为,用光学显微镜及电镜进行了直接观察与记录。并对氢致裂纹萌生及扩展的某些机理,诸如微裂纹与塑性变形的关系,热影响区微裂纹的萌生与硫化物夹杂的关系,以及断裂形式与显微组织的关系等问题,有了进一步的认识。