Reliability analysis of a human operator under different levels of stress

This paper presents a reliability analysis of a human operator carrying out his jobs under different levels of stress. The failed system, which is due to self-correctable error, is restored to as-new at normal stress. Laplace transforms of state probabilities and operator reliability are derived. The mean time to human error is also given.     

On the dynamic characteristics of a balance PUMA-760 robot

To reduce complexities in robot dynamics, a mechanical counter-balancing concept based on the theory of adding balancing masses to unbalanced conventional manipulators is introduced. The effects of balancing on the dynamic characteristics of the PUMA-760 robot when the designed counter-balancing mechanism is applied to the robot are examined. Through theoretical and experimental study many distinct advantages such as simplicity in the dynamic equation and significant reduction in the total required input torques are demonstrated for various manipulator speeds and payload conditions. Based on these results, the dynamic characteristics of the balanced PUMA-760 robot are discussed in detail     

Analysis of the calendering of compressible fluids

Assuming that the compressible behavior of polymeric melt obeys the Spencer–Gilmore equation of state, the effect of melt compressibility on calendering process has been investigated. The compressible model is distinctly different from the incompressible model in three ways. (1) It has substantially lower maximum pressure, (2) the location having maximum pressure moves closer to the nip region; (3) the contact point shifts closer to the nip region.     

Deep-submicrometer MOS device fabrication using aphotoresist-ashing technique

A photoresist-ashing process has been developed which, when used in conjunction with conventional g-line optical lithography, permits the controlled definition of deep-submicrometer features. The ultrafine lines were obtained by calibrated ashing of the lithographically defined features in oxygen plasma. The technique has been successfully used to fabricate MOSFETs with effective channel length as small as 0.15 μm that show excellent characteristics. An NMOS ring oscillator with 0.2-μm devices has been fabricated with a room-temperature propagation delay of 22 ps/stage. Studies indicate that the thinning is both reproducible and uniform so that it should be usable in circuit as well as device fabrication. Since most polymer-based resist materials are etchable with an oxygen plasma, the basic technique could be extended to supplement other lithographic processes, including e-beam and X-ray processes, for fabricating both silicon and nonsilicon devices and circuits     

Fatigue behavior of niobium-hydrogen alloys

The effects of hydrogen on room temperature fatigue behavior of niobium were investi-gated under both high frequency stress control and low frequency strain control condi-tions, in air. Hydrogen markedly improved the fatigue life in high frequency tests, while low frequency tests resulted in decreased fatigue life with increasing hydrogen content. Notches in hydrogen-charged alloys reduced high cycle life significantly but had little ef-fect on low cycle tests. Fracture surfaces of annealed niobium mainly exhibited striations, with numerous cracks originating at troughs of striated bands in both stress and strain control tests. The fracture mode for alloys with hydrogen in solution was mixed, with striations interspersed with cleavage facets at high frequencies but generally cleavage steps at low frequencies. For the hydrided alloys, distinctive steps of mixed ductile-brit-tle appearance were revealed under high frequency conditions, but large cleavage facets only were observed for low frequency tests. The results are discussed in terms of the effects of hydrogen on the cyclic strain hardening rate, as well as on fatigue strength and ductility of niobium.     

Transmission of X-rays through curved waveguides

The transmission of x-rays through curved cylindrical waveguides is investigated as a function of the guide diameter and the radius of curvature. Measurements were made atlambda = 1.54Å using lead glass capillaries with bore diameters ranging from 150 to 250 μ. It was observed, for example, that for a 150 μm diameter capillary 51.5 cm long, the transmission was reduced by a factor e^-1for a radius of curvature equal to 20 m. A model based on meridian ray analysis is presented and compared with the results of the experiment.     

Linkage analysis of infantile pyloric stenosis and markers from chromosome 9q11-q33: no evidence for a major gene in this candidate region

In order to investigate useful indicators of lead contamination, 108 Japanese Black calves from a lead-contaminated farm were used. The lead concentrations in blood (Ph-B), delta-aminolevulinic acid dehydratase (ALA-D) activities, and free erythrocyte protoporphyrin (FEP) concentrations were examined. A significant negative correlation was obtained between Pb-B concentrations and ALA-D activities (r = -0.621, p < 0.01). A significant positive correlation was obtained between Ph-B concentrations and FEP concentrations (r = 0.850, p < 0.01). The calves were divided by Pb-B concentrations (micrograms/100 ml) into 5 groups (A = < or = 30, B = 31 approximately 90, C = 91 approximately 150, D = 151 approximately 210, E = > or = 211) to observe the relation of ALA-D activities, FEP concentrations and ALA-D activities in group B (r = -0.706, p < 0.05). A significant positive correlation was obtained between Pb-B concentrations and FEP concentrations in groups A, B and D (A = r = 0.496, p < 0.01; B = r = 0.686, p < 0.01; D = r = 0.529, p < 0.05). These results indicate that FEP concentrations were good indicators of lead contamination.     

In situ X-ray diffraction study of melting in gold contacts to gallium arsenide

By in situ X-ray diffraction, we have obtained direct evidence for the distinction in melting temperature between the first and subsequent heating in ～ 1000 Å gold contacts to GaAs. During the first heating, melting occurred at 456–500°C and is attributed to the melting of a reaction product tentively identified as the orthorhombic AuGa compound (50 at.% Ga), which formed in the solid state. The minimum temperature required for the solid-state reaction and the melting temperature decreased with decreasing hydrostatic pressure. During second and subsequent heating, melting occurred at 410–415°C and is attributed to the melting of β AuGa (or Au₇Ga₂), which formed after the first melting-solidification cycle. At high cooling rates (e.g. 40°C/min) during the first solidification, β was observed together with a phase (tentative Au₂Ga) which increased in proportion with increasing cooling rate.