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91.
To evaluate the mechanical strength of fiber reinforced composites it is necessary to consider singular stresses at the end of fibers because they cause crack initiation, propagation, and final failure. The singular stress is expressed by generalized stress intensity factors defined at the corner of fibers. As a 2D model an interaction between rectangular inclusions under longitudinal tension is treated in this paper. The body force method is used to formulate the problem as a system of singular integral equations with Cauchy-type or logarithmic-type singularities, where the unknown functions are the densities of body forces distributed in infinite plates having the same elastic constants as those of the matrix and inclusions. In order to analyze the problem accurately, the unknown functions are expressed as piecewize smooth functions using two types of fundamental densities and power series, where the fundamental densities are chosen to represent the symmetric stress singularity of 1/r
1–
1 and the skew-symmetric stress singularity of 1/r
1–
2. Then, generalized stress intensity factors at the end of inclusions are systematically calculated for various locations, spacings and elastic modulus of two rectangular inclusions in a plate subjected to longitudinal tension. 相似文献
92.
Kawano K. Kohtoku M. Wada M. Okamoto H. Itaya Y. Naganuma M. 《IEEE journal of selected topics in quantum electronics》1996,2(2):348-354
In order to develop spotsize-converter-integrated laser diodes (SS-LDs) with high efficiency and large-misalignment tolerances in the 13-μm-wavelength region, spotsize converters (SSCs), which consist of lateral taper, thin-film core and ridge, are investigated employing the three-dimensional (3-D) semivectorial finite-difference beam propagation method (FD-BPM) with nonequidistant discretization. The sum of the spot-conversion loss and coupling loss between the laser diode (LD) eigenmode and the single-mode fiber (SMF) eigenmode are calculated for various structural parameters. Small loss of around 1.5 dB can be achieved by introducing a nonlinear taper. The fabrication tolerances for the SSCs are also clarified. The calculated results agree well with the results for actually fabricated SS-LD's. It is also shown that the radiation loss and coupling characteristics of the SS-LDs with a buried thin-film core structure can be improved using a nonlinear taper 相似文献
93.
Tetragonal to monoclinic phase transformation of yttria-stabilized zirconia, namely plasma-sprayed coatings and sintered bodies containing 4–8 mass % Y2O3 during hydrothermal aging was investigated with respect to Y2O3 distribution using 1 m area from electron probe microanalysis (EPMA) and 20 nm area from transmission electron microscopy (TEM) analysis. Phase transformation at 473 K was prevented only in plasma-sprayed coatings having more than 6.7 mass % Y2O3 in 20 nm microscopic area. Furthermore, it was confirmed influence of Y2O3 distribution on the rate constants of this phase transformation was observed at 368 K. 相似文献
94.
D Robinette S Wada T Arroll MG Levy WL Miller EJ Noga 《Canadian Metallurgical Quarterly》1998,54(5):467-475
BACKGROUND: A major reduction in the energy demand of the myocardium results from the electromechanical arrest, and cooling contributes to a lesser degree to this reduction. It is from this assumption that strategies of myocardial protection, utilizing warm blood cardioplegic induction, followed by cold cardioplegia with terminal warm reperfusion before removal of the aortic cross clamp, became established as optimal myocardial protection. Continuous normothermic perfusion 'closed the loop' by avoiding myocardial ischemia and linking warm induction and terminal reperfusion. A series of laboratory and clinical data confirmed the benefits of warm heart surgery on myocardial function and metabolism. The disadvantages of continuous warm blood cardioplegia including disturbance of the operative field, led surgeons to administer warm hyperkalaemic blood intermittently as a new cardioplegic strategy. METHODS: This review examines the laboratory and clinical data with reference to the intermittent warm blood cardioplegia, to establish its experimental basis and place in clinical practice. CONCLUSIONS: Experimental observation and clinical application have established intermittent warm blood cardioplegia as a practical, effective and cheap myocardial protection technique, particularly with reference to coronary artery surgery. 相似文献
95.
The literature suggests that seizure disorders are associated with an increased likelihood of intellectual problems, prompting researchers to investigate risk factors of cognitive impairment in epileptic patients. This study examined the contribution of certain variables (age of seizure onset, duration, etiology, seizure location and laterality, sex, handedness, and cerebral speech pattern) to cognitive outcome in patients with medically refractory seizures. Seizure location (temporal or extratemporal), age of onset of seizures, and handedness proved to be the best indicators of general intellectual ability. There was a relatively diverse pattern of relationships when neuropsychological tests of language, visuospatial ability, and memory were considered individually. However, a factor analytic approach revealed a simpler pattern in which location of dysfunction, age at seizure onset, hand preference, cerebral speech dominance, and gender were relevant and independent indicators of verbal and nonverbal ability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
96.
8,16-Ethanoretinal 3 was synthesized from 2-methylcyclohexanone. From the binding experiments of 3 and 8,18-ethanoretinal 2 with apoproteins of sensory rhodopsin I and phoborhodopsin, it was found that retinal was incorporated as 6s-trans conformation in the both proteins. 相似文献
97.
M Kushiro K Shikata H Sugimoto Y Shikata N Miyatake J Wada M Miyasaka H Makino 《Canadian Metallurgical Quarterly》1998,53(5):1314-1320
Prostacyclin (PGI2) is known to have a relaxative action on vascular smooth muscle, an inhibitory action against platelet activation and neutrophil function. Previous studies showed the preventive effects of PGI2 on lupus nephritis and Thy-1 nephritis, although the mechanism has not been clarified. Glomerular endothelial expression of intercellular adhesion molecule-1 (ICAM-1) is up-regulated in experimental and human glomerular diseases, and is known to facilitate leukocyte infiltration into the glomeruli, which ultimately induces the various glomerular injuries. In the present study, we evaluated the therapeutic effects of PGI2 on a rat model for crescentic glomerulonephritis and investigated its putative mechanism in relation to ICAM-1-mediated leukocyte recruitment. Wistar-Kyoto (WKY) rats were injected with nephrotoxic serum and received continuous intraperitoneal infusion of PGI2. PGI2 dramatically decreased proteinuria (123.0 +/- 18.8 vs. 31.6 +/- 4.5), crescent formation and deposition of fibrinogen in the glomeruli, while the deposition of rabbit IgG, rat IgG and rat C3 along the capillary walls was not changed. Furthermore, intraglomerular expression of ICAM-1 and infiltration of macrophages were significantly suppressed by administration with PGI2. In contrast, influx of CD4 or CD8 positive cells was not altered. The present results suggest that PGI2 shows the preventive effects on experimental crescentic glomerulonephritis by inhibiting intraglomerular coagulation and ICAM-1-mediated macrophage-glomerular endothelial cell adhesive pathway. 相似文献
98.
99.
H Wada 《Canadian Metallurgical Quarterly》1998,15(9):1189-1194
Whether the ancestral chordates were free-swimming or sessile is a longstanding question that remains to be settled. Vertebrates and amphioxi are free-swimming, but the most basal chordate subphylum (the urochordates) includes both sessile and free-swimming species. Here, 1 report molecular phylogenetic analyses of 18S rDNA of urochordates to deduce which lifestyle is ancestral. This revealed a close relationship between salps and doliolids and paraphyly of the ascidians. An early divergence of larvaceans, which show a tadpole-like body plan throughout life, is also supported by the analyses. Based on this phylogeny, a free-swimming ancestor for chordates is more parsimonious than a sessile ancestor. The evolutionary history of various lifestyles of chordates from this ancestral form is proposed. 相似文献
100.
This paper describes the microcleaved facets (MCF) process developed for AlGaAs/GaAs laser fabrication which can avoid the previous substrate cleavage and therefore be applicable to preparing both discrete short-cavity lasers and optoelectronic integrated circuits (OEIC's). An AlGaAs/GaAs double heterostructure ridge-waveguide laser with an extremely short cavity length, namely 20 μm, was first realized by this process. A threshold current as low as 20 mA and a single longitudinal mode lasing were achieved. The usefulness of this process for integrating a laser and a monitoring photodiode on a GaAs substrate is also demonstrated. 相似文献