Tension-tension fatigue behavior of GFRP woven laminates at low temperatures

This paper describes an experimental study on the fatigue damage behavior of GFRP woven laminates in terms of stiffness degradation and residual strength under cyclic loading at low temperatures. Uniaxial, load-controlled, tension-tension fatigue tests were conducted at room and low temperatures. The applied stress versus cycles to failure (S-N) relationships and fatigue limits were obtained for the GFRP woven laminates and the microcrack evolution due to fatigue loading was characterized using optical microscopy. Temperatures were also measured using a thermocouple embedded in the center of the specimens.     

Cat-CVD-prepared oxygen-rich μc-Si:H for wide-bandgap material

Microcrystalline phase-involved oxygen-rich a-Si:H (hydrogenated amorphous silicon) films have been obtained using catalytic chemical vapor deposition (Cat-CVD) process. Pure SiH₄ (silane), H₂ (hydrogen), and O₂ (oxygen) gases were introduced in the chamber by maintaining a pressure of 0.1 Torr. A tungsten catalyzer was fixed at temperatures of 1750 and 1950 °C for film deposition on glass and crystalline silicon substrates at 200 °C. As revealed from X-ray diffraction spectra, the microcrystalline phase appears for oxygen-rich a-Si:H samples deposited at a catalyzer temperature of 1950 °C. However, this microcrystalline phase tends to disappear for further oxygen incorporation. The oxygen content in the deposited films was corroborated by FTIR analysis revealing SiOSi bonds and typical SiH bonding structures. The optical bandgap of the sample increases from 2.0 to 2.7 eV with oxygen gas flow and oxygen incorporation to the deposited films. In the present thin film deposition conditions, no strong tungsten filament degradation was observed after a number of sample preparations.     

Coexistence of Vortex Liquid and Solid in Rotating Bose-Einstein Condensate

No Heading We perform computer simulations for the Gross-Pilaevskii equation with a tiny damping in order to study the condensate wave-function in 3-D rotating Bose-Einstein condensate under the trapping potential. We find that the wave-function is divided into two kinds of phases in terms of its coherent feature. The first one is a coherent phase which is characterized by the static vortex lattice located close to the center of the trapping potential, and the second one is an incoherent one which lies outside the first coherent phase and shows vortex liquid like behaviors. The boundary between the two phases is quite sharp like the phase interface as seen in the first-order phase transition. This result suggests that the melting seen in type II superconductors spatially occurs in the rotating Bose-Einstein condensate since the wave-function amplitude decreases with departing from the center of the trap and its coherent feature is overcome by intrinsic fluctuations at a certain distance.PACS numbers: 03.75.Lm, 03.75.Kk, 74.25.Qt, 74.40.+k     

Modelling of transition mechanisms from steady to oscillatory Marangoni flows in a liquid bridge configuration

In this paper, the transition mechanism from steady to oscillatory flow of Marangoni convection is investigated. Two-dimensional simulations for high Pr number fluids with several liquid bridge sizes were conducted in order to clarify the effect of temperature distribution on free surface upon the transition phenomena. The dependency of liquid bridge size on the onset of oscillatory flow was also evaluated. The results show that the formation of velocity distribution on the free surface is related to liquid bridge size and that it has a great influence on the onset of oscillation. From these results, a basic model for understanding the transition mechanism of Marangoni convection is proposed. In this transition model, the temperature distribution on the free surface was evaluated over a wide range of Pr numbers. A useful dimensionless parameter which indicates the onset of oscillation, the effective Marangoni number, is also proposed and evaluated.     

Ultra-sensitive high-speed density measurement of the “piston effect” in a critical fluid

In order to conduct a detailed investigation of the piston effect, the peculiar heat transportation phenomenon in critical fluids, an ultra-sensitive high-speed density measurement system was developed using a very thin heater, a sensitive interferometer and a large-capacity high-speed data acquisition system. As the first step of the investigation, an experiment was conducted to measure the velocity of sound in CO2 near its critical point. Short heat pulses suppressing the disturbance of natural convection were applied to a small cell filled with almost-critical CO2 fluid and were detected by the measurement system. Because the pulses propagated through the cell at the velocity of sound and were reflected several times between the cell walls, the velocity could be precisely determined by measuring the time intervals between successive reflections. The resulting velocity profile versus temperature showed good agreement with theoretical prediction and numerical simulations. This result validated the density measurement system, and it is considered that the measurement system will be a very effective tool for further studies on critical phenomena with the aid of numerical simulation.     

Surface tension of molten stainless steels under plasma conditions

The surface tension and the density of 304 stainless steels with the sulfur contents of 10, 100 and 250 ppm were measured under low pressure Ar plasma conditions in the temperature range of 1823–2073 K. The measurements were carried out by the sessile drop method and a (La_0.9Ca_0.1)CrO₃ substrate was used. No significant influence of the plasma was observed on the surface tension and its temperature coefficient. The surface tension and density of 304 stainless steel are expressed using the following equations: $$ \displaylines{ \gamma = - 0.12\times T + 1980 \ ({\rm mN/m}) \quad (10 \,{\rm ppm\, Sulfur})\cr \gamma = 0.29\times T + 1030 \ ({\rm mN/m})\quad (110 \,{\rm ppm \,Sulfur})\cr \gamma = 0.49\times T + 520\ ({\rm mN/m})\quad (250 \,{\rm ppm \,Sulfur})\cr \rho = - 0.616\times T + 8.11\times 10^{+3 } \ ({\rm kg/m^{3}})\cr} $$      

Method of evaluation of distribution characteristics of flaky inclusions*

In order to evaluate the maximum size of the flaky inclusions in a Si-added noncombustible Mg casting alloy, we propose a method for evaluation of distribution characteristics of flaky inclusions. The validity of this method is verified through simulations with arbitrary inclusion distributions. The proposed method enables prediction of the maximum size of the flaky inclusions in an arbitrary volume of material.     

A high-density data-path generator with stretchable cells

This paper describes a newly developed module generator for cell-based design which generates a data-path layout comparable to a handcrafted one both in speed and in transistor density. The chip designer enters his schematic data-path diagram using the configurable function block library provided. There is no constraint either in the number of function blocks used, or in how to interconnect them. The data-path generator generates the function blocks, which are components of the data-path, and automatically places and routes them. The configurable function blocks were developed in 0.8-μm double metal CMOS technology. A new cell structure suitable for over the cell routing, called “stretchable cell with access free terminals,” is adopted as a bit-slice element of the data-path generator. This removes the routing region outside the cell for the wiring between function blocks, and a high density layout can be obtained. Also because of the new cell structure, there is no upper limit on the number of tracks per bit. Using this data-path generator, several data-paths were generated with high density of more than 6k Trs./mm²     

Coagulase typing of Staphylococcus aureus in the geriatric wards after introduction of preventive measures of hospital infection

The study comprised 323 cryptorchidic boys, between 6 months and 14 years of age (mean age 5.68 years) with 440 maldescended testes. Testicular position was graded as inguinal low or prescrotal (I), inguinal middle (II), inguinal high (III), and abdominal testes (IV). Boys before 4 years of age received human chorionic gonadotropin (hCG) as intramuscular injections (I.M.), 500 IU twice a week for 5 weeks; and boys 4 or more years of age received hCG (IM), 1000 IU twice a week for 5 weeks. The objectives of this study were to evaluate the response of maldescended testes to treatment with hCG, and to investigate possible associations between the patients' ages and position of the testes with the response to hCG. Out of the 440 maldescended testes, 329 were in an inguinal location (75%) and 111 were abdominally located (25%). The overall response to hCG was 40%, and the inguinal testes response was 49%, with the highest success rates (72%) for the prescrotal testes. A positive correlation was found (p < .0001) between the rate of success and the testicular position. There was no association between the hCG response and the age at which treatment was initiated.