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981.
M. Hamacher D. Trommer K. Li H. Schroeter-Janssen W. Rehbein H. Heidrich 《Photonics Technology Letters, IEEE》1996,8(1):75-77
An optimized integration process is reported requiring only three epitaxial growth steps for the fabrication of an OEIC encompassing a single-mode laser, a waveguide element, and fast photodiodes. The process was applied to the fabrication of a heterodyne receiver including a semi-insulating buried heterostructure (SIBH)-DFB-laser with an output power of 14 mW and a side-mode suppression ratio greater than 40 dB, a 3-dB coupler, and high-speed balanced photodiodes with a bandwidth of 9 GHz. The laser can also be used as a transmitter laser exhibiting a modulation bandwidth of 11 GHz. 相似文献
982.
State- and time-dependent routing in the NTT network 总被引:1,自引:0,他引:1
The purpose of state- and time-dependent routing (STR) is to achieve high performance despite unpredictable real-time traffic fluctuations, with minimum changes to existing switching software and operations systems. STR uses an appropriate combination of the two kinds of control, centralized and distributed. The article gives an overview of STR and its advanced call-level routing, describes the current STR network and the performance of STR with two examples from the NTT network, and addresses a dimensioning method for STR 相似文献
983.
The authors present a method for solving a class of optimization problems with nonsmooth constraints. In particular, they apply the method to the design of narrowband minimum-power antenna array processors which are robust in the presence of errors such as array element placement, look direction misalignment, and frequency offset. They first show that the constrained minimum power problem has a unique global minimum provided that the constraint set is nonempty. Then it is shown how the design problem derived directly from considerations of the sensitivity of the antenna array processor to errors can be transformed into a quadratic programming problem with linear inequality constraints which can be solved efficiently by the standard active set strategy. They also present numerical results for two types of nonsmooth constraints developed to provided robustness. These results confirm the effectiveness of the method 相似文献
984.
An approach to accurate and efficient computation of dielectric losses in complex microstrip structures is proposed. It can be used in lieu of lossy, full-wave solutions to provide accurate and efficient data for the CAD of multilevel, multiconductor MIC and MMIC structures. Results that are as accurate as lossy full-wave techniques over a wide range of frequencies, including the dispersive region, are obtained. In addition to providing accurate results, the method is up to three times faster, depending on the number and type of substrates or superstrates. Results for various multiconductor, multilevel structures that compare well with the lossy, full-wave approach and require significantly less computer time to compute are shown 相似文献
985.
LW Didenko IB Buchwalow W Schulze K Augsten M Susa E Unger 《Canadian Metallurgical Quarterly》1996,98(4):399-409
Heterotrimeric GTP-binding proteins (G-proteins) have been shown to play an important role in cellular signalling. However, G-protein involvement in the intracellular spreading of bacterial pathogens is still poorly understood. In this study, antibodies, that recognize G-protein alpha-subunits (anti-G alpha), were used to investigate the localization of G-proteins in the macrophage-like cell line P388D1 and E. coli, also in their L-forms, during phagocytosis. In E. coli, anti-G alpha-binding sites were detected preferably in the cell wall and septa of the whole bacterial forms as well as in the cytoplasm of L-forms. Western blotting of bacterial lysates demonstrated protein bands with positive immunoreaction to antibodies against Gs alpha, Gi alpha, and Gcommon alpha with a higher affinity to the antibody against Gs alpha. Immunoreaction with the anti-Gs alpha-antibody was markedly higher in pathogenic strains of E. coli. Because of the conserved structure in all GTP-binding proteins which seem to derive from a single primordial protein involved in signal transduction mechanisms, it is reasonable to assume that some anti-Ga-positive proteins in E. coli might be related to G-proteins of higher organisms. A putative candidate for bacterial G-proteins seems to be a 36 kDa protein. Enhancement in G-protein immunostaining in the cytoplasm of macrophages around the internalized bacteria testifies to the involvement of G-proteins in mediation of endocytosis responses of phagocytes. 相似文献
986.
J. E. G. Hulshoff K. Van Dijk J. P. C. M. Van Der Waerden W. Kalk J. A. Jansen 《Journal of materials science. Materials in medicine》1996,7(10):603-609
The bone response to different calcium phosphate (Ca-P) coated implants was evaluated in a goat animal model. Two types of plasma spray coatings were applied to a commercially pure titanium (cpTi) tapered, conical screw-design implant (BioComp®); hydroxyapatite (HA-PS) and a dual coating, consisting of FA and HA (FA/HA-PS). In addition an amorphous RF magnetron sputter coating (Ca-P-a) and uncoated implants were investigated. Forty-eight implants were inserted in the maxilla of 12 adult female goats. After implantation periods of 3 and 6 months, the bone implant interface was evaluated histologically and histomorphometrically. After both implantation periods all plasma spray coated implants were maintained. On the other hand three Ca-P-a and two cpTi implants were lost. Histological examination revealed a better bone response to both plasma spray coated implants. Histomorphometrical evaluation confirmed this finding. At 3 and 6 months significantly higher percentages of bone contact (p<0.001, ANOVA) were measured for both plasma spray coated implants than for the cpTi and Ca-P-a implants, while no significant difference (p<0.05) existed between both implantation periods. Degradation of both plasma spray coatings was observed. Supported by the results, it is concluded that, although Ca-P coatings can improve the performance of dental implants, the presence of a Ca-P coating is not the only important factor for bone healing around implants placed in low density trabecular bone. 相似文献
987.
Examining 230 edentulous patients, a significant degree of atrophy in the maxilla and mandible relatively often has been found. Atrophy could be detected more often in the mandible of female patients. For these forms of manifestation, among others, systemic causes: osteoporosis, diabetes and periodontal disease could be found. The results and their classification may help to draw the attention in the course of treatment to strong dissimilarities or similarities of the edentulous mouth. The degree of atrophy observed on both jaw-bones--among other factors--is significant for the planning and prognosis when indicating total prosthetic treatment. 相似文献
988.
989.
Planar infinite arrays, comprising longitudinal slots cut in ridged waveguides, are analysed using a Galerkin formulation for the tangential electric field at both slot interfaces, combined with the finite element method for generating the waveguide Green function used in the integral equation. Computations agree very well with previously documented results 相似文献
990.
S. K. Liu L. Yang D. G. Zhu J. Zhang 《Metallurgical and Materials Transactions A》1994,25(9):1991-2000
A series of Fe-C-X and Fe-C-X1-X2 alloys in which X, X1 and X2 either raise or depress the activity of C iny were investigated by autodilatometer, optical microscopy, and transmission electron microscopy (TEM) to reveal the relations
among the chemical composition, transformation kinetics, and morphology of ferrite plates. The incubation time of austenite
decomposition at the nose temperature in the time-temperature-transformation (TTT) diagrams, the concentration of C in y in
contact with theα/gg boundary, and the growth rate of ferrite were evaluated to estimate the magnitude of the solute drag-like
effect (SDLE) for the different alloying elements used. All the results are consistent qualitatively with the SDLE hypothesis.
This article is based on a presentation made at the Pacific Rim Conference on the “Roles of Shear and Diffusion in the Formation
of Plate-Shaped Transformation Products,” held December 18-22, 1992, in Kona, Hawaii, under the auspices of ASM INTERNATIONAL’S
Phase Transformations Committee. 相似文献