Development of solver system for FEM analysis of solder joints

This study was aimed at establishment of a model that can predict tensile shear strength and fracture portion of laser-welded lap joints in the tensile test. To clear the influence of bead length and bead width on them, the joints that used steel sheets with a thickness in the range of 0.8–1.2 mm were evaluated. It was found that the tensile shear strength increases with the bead size, and the fracture occurs at base metal (BM), weld metal (WM) or a portion between them with a curvature heat-affected zone (HAZ), in the tensile test. Also to clarify the rotational deformation process around WM during the tensile test, cross-sections of joints were observed, which were applied to several loads in the tensile test. This observation derived the relationship between the radius, R_i, at the inner plane of the HAZ and the rotational angle at the centre of the sheet thickness. Furthermore, the relationship between Ri and the applied load was obtained by linear regression. A plastic analysis for deformation of the joints was carried out based on these functions and some assumptions. These assumptions consider that the joint consists of BM, WM and HAZ, which are under a simplified stress mode. Finally, estimation of the tensile shear strength and the fracture portion of the joints was achieved. This estimation made good accordance with the experimental results.     

-Lysine production by exponential feeding of -threonine

The effect of -threonine feeding in the production phase on -lysine production by Brevibacterium flavum, which requires -homoserine or -threonine for cell growth, was investigated considering the concerted inhibition by -threonine plus -lysine, and the metabolism related to lysine production. Exponential feeding of -threonine increased -lysine production to 70 g/l about three times that without feeding. From the analysis of the metabolic flux, carbon flux of -lysine synthesis pathway in the production phase after -threonine feeding was higher than that in the growth phase. The results show that feeding of an inhibitory substance may increase the production, especially when the substance is necessary for the continuation of cell growth and/or production.     

Diamond synthesis by weak shock loading

A hexagonal polymorph of diamond has been synthesized by relatively weak shock loading (in a range of projectile velocity 0.655 to 1.88 km sec^–1) with a recovery technique. Four mixtures of copper with spectroscopic graphite, amorphous carbon, glassy carbon and graphite fluoride, with densities of 4.8 to 7.8 g cm^–3, were used to control the shock temperature rise and to quench efficiently. Spectroscopic graphite gave the maximum yield of diamond (8%). Chaoite was also observed in the shocked amorphous carbon and glassy carbon. A local temperature rise during shock was inferred from the temperature of some spherical particles, indicative of superheating of the particles to near or above the melting point.     

Behavior of a tip of non-propagating fatigue crack during one stress cycle

Measurements and observations were made on the crack closure for the so-called non-propagating crack of notched specimens and for the non-propagating microcrack of unnotched specimens, which were formed in a rotating bending test of annealed carbon steel. Under the condition which produces the non-propagating crack, the ratio of stress range where the crack tip is open, to the full range of the cyclic stress tends gradually to zero with the increase in length of the crack initiated from a notch root.The tip of a non-propagating microcrack on the surface of a plain specimen is also recognized to be closed under the maximum stress level after 10⁷ cycles of the repetitions of the stress slightly below the fatigue limit.From these facts, it can be said that the tip of a so-called non-propagating crack or a non-propagating microcrack is hardly damaged by the repetition of stress which has produced each crack.     

Regulation cf Intermediates on Sulfided Nickel and MoS2 Catalysts

Dramatic developments have been seen in the application of varous modern tools in heterogeneous catalysis which makes it feasible to understand the catalytic reactions as well as the catalysts themselves on a molecular and/or atomic scale. consequently, much more attention has been paid to the configuration of active sites in relation to their caralytic behaviors.     

Cationic graft copolymerization of tetrahydrofuran onto bromodeoxycellulose

Cationic graft copolymerization of tetrahydrofuran onto halodeoxycelluloses, which were prepared under homogeneous conditions, was studied with silver tetrafluoroborate as an initiator. 6-Bromo-6-deoxycelluloses gave graft copolymers, insoluble but swollen in tetrahydrofuran, whereas chlorodeoxycelluloses gave no graft copolymer. The graft copolymers were hydrolyzed in 2N HCl to give hydrolyzate solutions and insoluble solids. The hydrolyzate was found to be composed of 6-O-(4-hydroxybutyl) glucose and 6-O-(9-hydroxy-5-oxanonyl) glucose as well as oligomers of tetrahydrofuran by gas chromatography and gas chromatography–mass spectrometry after trifluoroacetylation. The insoluble solid was cross-linked polyoxytetramethylene, which could be hydrolyzed only very slowly in 2N HCl to yield oligomers of tetrahydrofuran. Thermal behavior of the graft copolymer was compared with that of cellulose and of homopolymer of tetrahydrofuran. © 1994 John Wiley & Sons, Inc.     

Stereological determination of structural anisotropy

A general mathematical formulation is given to the problem of determining the structural anisotropy by means of the stereological principle. Three cases are considered—distributed curves in the plane, distributed curves in the space and distributed surfaces in the space. The number of intersections with a probe line or plane is viewed as a transformation, which is termed the “Buffon transform”, between two distribution densities, and a form of its inverse transform is given. Then, the change of anisotropy due to the deformation of the material is formulated, and the strain is shown to be determined from the data of the intersection counting. All equations are written in the form of Cartesian tensor equations invariant to coordinate translations and rotations. A typical example is also given.     

Noninvasive Measurement of Hematocrit by Electrical Admittance Plethysmography Technique

A new method for the noninvaive measurement of hematocrit by means of electrical admittance plethysmography was developed. The pninciple of this method is based on the evidence that the elecical admittance variation in a finger segment inmersed in an electrolyte solution disappears when the resistivity of the solution is equal to that of the blood flowing into the segment. Thus, the blood resistivity and, therefore, the hematocrit can be noninvasively determined from the electrolyte resistivity. The hematocrit values determined by this method (HctY) were compared with those by the capillary method (Hctc) in 16 subjects: the linear regression equation was HctY = 1.02Hctc-0.35 with a correlation coefficient r = 0.981.