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991.
A. Bhattacharya 《International Journal of Fracture》1996,78(2):131-138
A complex analysis of rigid body rotation is presented. The crack-tip rotation for a line crack subjected to steady uniform heat flow is obtained in terms of thermal stress intensity factor in shear mode of the crack, the material and thermal parameters and coordinates of points close to the crack tip. The shear strip configuration is analysed on the basis of rotation and displacement at the end of the shear strip. 相似文献
992.
J. H. Edgar C. A. Carosella C. R. Eddy Jr D. T. Smith 《Journal of Materials Science: Materials in Electronics》1996,7(4):247-253
The effects of nitrogen-beam voltage on the structure, stress, energy band gap and hardness of AIN thin films deposited on Si (111), Si (100) and sapphire (0001) by ion beam assisted deposition (IBAD) are reported. As the nitrogen-beam voltage was increased from 50 to 200 V, the stress and disorder in the AIN films increased as determined by X-ray diffraction, FTIR and Raman spectroscopy. The preferred orientation of the film's c-axis changed from completely normal to the film at 100 V, to a mixture of normal and in the plane of the film at 200 V. For AIN films deposited under the same conditions, the films were more highly oriented on sapphire (0001) than in Si (111). The hardness of the films increased from 18.2 to 23.7 GPa with the nitrogen-beam voltage, and possible reasons for this change in hardness are considered. 相似文献
993.
Silicon forms the backbone of the microelectronics industry, and possibly, of the optoelectronics industry, hitherto dominated by III/V materials. One of the remaining goals is to build an optical source in silicon. Erbium exhibits luminescent 1.54 μm intra-4f transitions in both silicon and porous silicon. This paper reviews the work which has been carried out in this field and discusses some possible additional applications of erbium-doped silicon in optoelectronics, such as a novel on-chip temperature sensor. 相似文献
994.
This article considers a discrete sequential multilevel automated system for recording electron-diffraction patterns. A comparative
analysis is presented, along with experimental results that make it possible to evaluate the effectiveness of the technical
decisions on which the device is based. The general design of the system is presented.
Translated from Izmeritel'naya Tekhnika No. 5, pp. 16–18, May, 1996. 相似文献
995.
K Umakantham K Chandramouli G Nageswara Rao A Bhanumathi 《Bulletin of Materials Science》1996,19(2):345-355
Rare-earth doped strontium barium niobates were synthesized using usual ceramic technique. The dopants are La, Ce, Gd, Sm
and Nd. The materials were characterized by XRD and density measurements. The grain sizes were determined from SEM analysis.
Lattice parameters changed uniformly with rare-earth dopants in unfilled structures. Density measurements and SEM analysis
confirmed only minute changes in the densities of the ceramics. 相似文献
996.
D.A. Wesley 《Nuclear Engineering and Design》1993,142(2-3)
A proposed methodology and sample results from several plant investigations are presented for evaluating the expected pressure capacity of nuclear power plant components which could potentially be subjected to Interfacing Systems LOCA (ISLOCA) conditions. Included in this evaluation are tanks, heat exchangers, filters, pumps, valves and flanged connections for systems designed for relatively low-pressure, low temperature conditions, but which could possibly be exposed to reactor coolant conditions, either through human error or isolation valve failures. The probabilities of failure, as a function of internal pressure, are evaluated as well as the variabilities associated with them. Leak rates or leak areas are estimated for the controlling modes of failure. Pressure capacities for the pipes and vessels are evaluated using limit-state analyses for the various failure modes considered. The capacities are dependent on several factors, including the material properties, modeling assumptions, and the postulated failure criteria. The failure modes for gasketed-flange connections, valves and pumps do not lend themselves to evaluation by conventional structural mechanics techniques and evaluation must rely primarily on the results from ongoing gasket research test programs and available vendor information and test data. 相似文献
997.
E. M. Abdel-Bary H. H. Hassan A. M. El-Lawindy M. K. Abu-Assy F. K. El-Tantawy 《Polymer International》1993,30(3):371-374
Butyl rubber mixtures loaded with 70 phr general purpose furnace black (GPF) and tetramethyl thiuram disulphide (TMTD)/S as vulcanizing system were prepared. The kinetics of their electrical conductivity development during the vulcanization process were followed by using an especially devised system. It was found that the increase in the electrical conductivity during vulcanization obeys an exponential growth function with time constant τ, which markedly decreases with increasing vulcanization temperature as well as with the efficiency of the vulcanizing system. After completion of the vulcanization process, about 80 min, the samples obtained possess reasonable stability and reproducibility of electrical conductivity. 相似文献
998.
NIKIÉT. Translated from Atomnaya Énergiya, Vol. 75, No. 4, pp. 265-269, October, 1993. 相似文献
999.
A. P. Petrov 《Color research and application》1993,18(6):375-379
Color and Grassmann-Cayley Coordinates of Shape are considered in this article. The image irradiance equation for colored surfaces and the Grassman manifold λ of orbits Q = {B · h + c; detB ≠ 0} Where c is a vector sweeping the color space H, B is a 3 × 3 matrix, and h(x, y) is the color image of a Lambertian surface assumed to be a linear vector-function of the normal vectors. Different orbits Q(n) correspond to different shapes but they are invariant under color and illuminant transformation. Coordinates of an orbit Q in λ can be computed as 3 × 3 (2 × 2, sometimes) determining the elements of which are values of some linear functionals (receptive fields) of h(x, y). Based on the approach, a shape-from-shading algorithm was developed and successfully tested on the threeband color images of various real objects (an egg, cylinders and cones made of paper, etc.). © 1993 John Wiley & Sons, Inc. 相似文献
1000.
Subspace-based signal analysis using singular value decomposition 总被引:10,自引:0,他引:10
Van Der Veen A.-J. Deprettere E.F. Swindlehurst A.L. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1993,81(9):1277-1308
A unified approach is presented to the related problems of recovering signal parameters from noisy observations and identifying linear system model parameters from observed input/output signals, both using singular value decomposition (SVD) techniques. Both known and new SVD-based identification methods are classified in a subspace-oriented scheme. The SVD of a matrix constructed from the observed signal data provides the key step in a robust discrimination between desired signals and disturbing signals in terms of signal and noise subspaces. The methods that are presented are distinguished by the way in which the subspaces are determined and how the signal or system model parameters are extracted from these subspaces. Typical examples, such as the direction-of-arrival problem and system identification from input/output measurements, are elaborated upon, and some extensions to time-varying systems are given 相似文献