Numerical Study on Periodic Structure Evolution of Output Power in MHD Generator by Using Pulse‐Assisted Ionization Discharge

A pulse‐assisted ionization discharge applied to a magnetohydrodynamic (MHD) generator is proposed as a technique to increase an electrical conductivity of working fluid. In this study, a periodic structure of output power in the MHD generator by using pulse‐assisted ionization discharge was evaluated. As a result, the discharge electrode length and the velocity of working fluid affect the discharge current distribution. The periodic structure of output power was observed in the several conditions. When the velocity of working fluid is roughly same as the sound speed, the periodic structure of output power was not observed.     

APPLICATION OF TOPOLOGICAL OPTIMIZATION TECHNIQUES TO STRUCTURAL CRASHWORTHINESS

The topological optimization of components to maximize crash energy absorption for a given volume is considered. The crash analysis is performed using a DYNA3D finite element analysis. The original solid elements are replaced by ones with holes, the hole size being characterized by a so-called density (measure of the reduced volume). A homogenization method is used to find elastic moduli as a function of this density. Simpler approximations were developed to find plastic moduli and yield stress as functions of density. Optimality criteria were derived from an optimization statement using densities as the design variables. A resizing algorithm was constructed so that the optimality criteria are approximately satisfied. A novel feature is the introduction of an objective function based on strain energies weighted at specified times. Each different choice of weighting factors leads to a different structure, allowing a range of design possibilities to be explored. The method was applied to an automotive body rear rail. The original design and a new design of equal volume with holes were compared for energy absorption.     

The analysis of change in occupational qualities by ageing

The ageing process was studied by means of the changes in the aptitude measured by the general vocational aptitude test constructed by the Japan Labour Ministry. The aptitudes were classified in terms of three activities, viz. analytical, synthetic and motion. Four groups of subjects participated in the study: 271 male manual workers aged 20-59; 111 male non-manual workers aged 20-59; 196 male and female university students aged 18-19; and 123 male and female junior high school students aged 13-15. Changes with age were observed in the scores, in the activity balance diagram and in the time required for the basic motion (therblig).     

Positive Creeping Discharge along Aerial Insulated Wire Generated by Lightning Stroke

There are two causes, inductive lightning surge and direct lightning stroke, as the aerial insulated wire accidents accompanying lightning in a power distribution system. When the overvoltage due to the inductive lightning surge invades to the wire core, the creeping discharge can develop along the wire surface from the free end of the binding wire just after a flashover of the post insulator at the wire supporting point. This creeping discharge may give rise to the accidents such as a melting or snapping of the wire. The creeping discharge along the wire surface has the positive or negative polarity. Positive creeping discharge is restricted to the area where a positive lightning generates. Only a few examples have been reported on the positive creeping discharge, and its characteristic has many unsolved points. In the previous studies, we have observed the positive creeping discharges along the wire surface under the negative inductive lightning surge with the peak values in the range |V_m| ≤80 kV. In this study, the positive creeping discharges are examined newly in the range |V_m| > 80 kV. It is reported that the positive creeping discharges are greatly affected by the negative corona discharges generating from the wire surface in |V_m| ≥ 95 kV.     

Sugar and Cyclitol Determination in Vegetables by HPLC Using Postcolumn Fluorescent Derivatization

Nonreducing sugars such as sucrose, raffinose, myo-inositol, pinitol and galactinol were separated on a polyamine-bonded polymer gel (NH₂ type) column using acetonitrile-water as mobile phase. Sugars in the eluate were detected by periodate oxidation and the subsequent derivation of guanidine to fluorescent compounds. Detection limits were: sucrose 2.5, D-glucose 2.5 and pinitol 4 ng. This highly sensitive method was more accurate and rapid for determining sugar contents in immature soybean seeds, sweet corn kernels and chinese mustard leaves than the conventional method using refractive index detection. Also, this method reduced the injection volumes of extracts to the column and allowed to lengthen the column life.     

Demixing of Materials under Chemical Potential Gradients

A steady-state demixing of initially homogeneous solid solution which occurs in binary oxides under oxygen partial pressure gradient is treated by the path probability method of irreversible statistical mechanics from an atomistic point of view. The larger the difference between the diffusion coefficients of constituent species is, the larger is the degree of demixing. Essential features of demixing by diffusion, however, do not depend on whether the driving force is the chemical potential gradient, the electric field, or others.     

Demixing of Oxides under a Temperature Gradient

The microscopic mechanism of a demixing of binary oxide solid solution in an oxidizing atmosphere under a temperature gradient is investigated by the path probability method of irreversibly statistical mechanics. The problem is reduced to a steady-state metal ion transport under the coexistence of an oxygen partial pressure gradient and a temperature gradient. Calculations are performed under two different conditions: (i) demixing in a steady-state diffusion process under the two driving forces and (ii) a redistribution of constituent metal ions in a closed system under a given temperature gradient (Soret effect). The results can be interpreted as the superposition of the contributions of two driving forces plus a cross term which tends to zero as the driving forces become small. The difference between these two cases is discussed in detail and some controversies in the past work with respect to the difference are pointed out.     

Survey of Rabbit Skeletal Muscle Peptidases Active at Neutral pH Regions

A survey of oligopeptide hydrolases active at neutral pH regions responsible for increased free ammo acids on aging of high ultimate pH muscles were performed examining chromatographic behavior and substrate specificity of rabbit skeletal muscle extract. The DEAE-cellulose chromatography of muscle extract revealed five major activity peaks respectively ascribable to a dipeptidase, an aminotripeptidase, an ammopeptidase, leucine aminopeptidase and the 160,000 dalton-aminopeptidase purified previously by us. Since the 160,000 dahon-ammopeptidase showed a broader substrate specificity than the two other aminopeptidases, it is most likely that this enzyme shares the largest part in the tetrapeptide hydrolysis in rabbit skeletal muscle at neutral pH regions.     

Ni3Al—Mo高温复合材料的拉伸特性

采用定向凝固法制得Ni_3Al-Mo复合材料,以3.3×10~(-3),3.3×10~(-4),3.3×10~(-5)s~(-1)三种形变速度,分别在室温至1273K温度范围内作拉伸试验。结果发现,屈服应力随温度上升而增加,在973K附近,显示强度峰值,变形过程中,Mo纤维起着阻止位错运动,抑制塑性变形的作用。     

Preparation and mechanical properties of calcium phosphate/copoly-L-lactide composites

New artificial bone materials were prepared using calcium phosphates, hydroxyapatite and -tricalicum phosphate, and copoly-L-lactide, CPLA. Calcium phosphate powder and CPLA were mixed at 453 K for 10 min with various mixing ratios. Scanning electron microscope observations indicated that the composites of -tricalicum phosphate and CPLA were homogeneously dispersed and highly adhesive. Youngs modulus of the composites was the same as bone, and bending strength was over half that of bone. The improvement of Youngs modulus compared to the original two materials was due to a composite effect. The composites are expected to be usable as artificial bone materials.