Low-cycle fatigue properties of eutectic solders at high temperatures

This paper details the deformation mechanism and low‐cycle fatigue life of eutectic solder alloys at high temperature (around 0.8T_m). Grain boundary sliding generally nucleates a wedge‐type cavity that reduces the low‐cycle fatigue life of metals. In this study, grain boundary sliding has promoted intergranular failure contributing to the reduction in fatigue life of Sn–Ag–Cu alloy. However, grain boundary sliding has exerted no deleterious effects on fatigue resistance of eutectic Pb–Sn and Bi–Sn alloys. The phase boundary sliding with very fine microstructure induces exceptional ductility in these alloys leading to superior low‐cycle fatigue endurance for theses eutectic Pb–Sn and Bi–Sn alloys.     

Fuzzy control of a manipulator using an actuator and multibrakes

This paper is concerned with the control of a manipulator with n-degrees of freedom by one actuator and n ? 1 brakes using fuzzy inference. All the links of the manipulator are excited by a motor placed on the base link, and the excitation torque is successively transmitted through each link from the base link until the final link. The brakes on the joints act at identical frequency with different phases, and the phases of timing on the brakes are controlled by fuzzy inference such that all the joint angles of links are followed to the desired trajectories. The effectiveness of the proposed method is illustrated by a simple example.     

Structural integrity in electronics

With continuing miniaturisation, increased performance demands and the requirement to remove lead from solder alloys, the challenges to structural integrity and reliability of electronic equipment are substantial and increasing. This paper outlines typical features in electronic equipment of which the structural integrity community may be generally unaware. Potential failure modes in service are described, and the problems of scale and material characteristics are considered. Progress in the application of fracture mechanics to the life prediction of interconnections is reviewed. The limited evidence available suggests that the crack growth resistance of silver‐containing lead‐free solders is superior to that of the traditional Sn‐37Pb under cycle‐controlled conditions but there is no difference when time‐dependent conditions prevail. In several respects, it is contended that the electronics sector is faced with challenges at least equivalent to those encountered in gas turbines and nuclear power generation.     

n-Hexanol Formation from n-Hexanal by Enzyme Action in Soybean Extracts

n-Hexanal in soybean homogenates decreased during incubation at alkaline pH. When soybean extracts were dialyzed and then incubated with n-hexanal and cofactors [nicotinamide adenine dinucleotide (NAD⁺), the reduced form (NADH), nicotinamide adenine dinucleotide phosphate (NADP+), and the reduced form (NADPH)], NADH and NADPH stimulated the enzymatic reduction of n-hexanal with NADH being more effective than NADPH. When undialyzed preparations were incubated, all the cofactors stimulated enzymatic activity, with NADH being the most effective. The reaction product in all the incubation mixtures was n-hexanol; n-hexanal was reduced to n-hexanol stoichiometrically. It was suggested that alcohol dehydrogenase was responsible for the decrease of n-hexanal in soybean homogenate at alkaline pH.     

Heat-Induced Tendering of Turban Shell (Batillus cornutus) Muscle

The foot, opercular and visceral muscles were excised from the turban shell Batillus cornutus, and their heat-induced changes in toughness and ultrastructure were compared. When heated up to 30°C, the toughness of foot muscle decreased in the upper and middle regions, but increased in the lower region. The toughness of these three regions decreased at temperatures between 50-70°C, where collagen might be denatured. Some changes in toughness were also observed in the opercular muscle by heating up to 30°C, whereas the toughness of visceral muscle remained unchanged over a wide range of temperature. Transmission electron microscopy showed that the intrinsic structure of collagen fibrils in each muscle was lost at 60°C, with partial swelling.     

A Study on the Power System Security under Future Uncertainties

In this paper, we propose three applications to quantitatively evaluate N‐1 security with increased uncertainties. By using a robust dynamic security region (RDS), which is based on the concept of robust power system security (RS), the key region for judging the security and a new evaluation index for quantitative analysis, we can evaluate power system security as follows. (1) The calculation of the RDS at the time of yearly peak load demand can be recognized as the benchmark for the N‐1 security at present, and this method can be applied to the future power system with increased renewable energy resources (RES) such as PV. (2) We show the yearly declining trend for N‐1 security resulting from increased PV deployment year by year. (3) We calculate the necessary amount of additional power supply capacity, including conventional electric power generators or storage batteries, needed for maintaining the N‐1 security at the present level. The effectiveness of the proposed method is demonstrated through simulations using a model system with three machines.     

Heat-Induced Textural and Histological Changes of Ordinary and Dark Muscles of Yellowfin Tuna

When a fresh specimen of yellowfin tuna Neothunnus albacora was analyzed, the cross-sectional area of ordinary (white) muscle fiber was 3.5 times larger than that of dark muscle. As heating temperature was raised, the shear force of dark muscle became progressively larger than that of ordinary muscle. Simultaneously, the A band in the ultrastructure of both muscles was stained more densely. While the Z line in I band of dark muscle still remained, that of ordinary muscle disappeared completely by heat treatment at 60°C for 30 min. Therefore, the differences in toughness change during heat treatment correlated well with that fiber sizes and ultrastructures of the two types of muscle.