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排序方式: 共有1323条查询结果,搜索用时 15 毫秒
1.
Gladson S. Chrisben Prasad P. Siva Manickam Bhaskar 《Analog Integrated Circuits and Signal Processing》2021,109(3):571-583
Analog Integrated Circuits and Signal Processing - As the 5G era beckons in the world of communication and information technology, there is a surge in demand for battery-operated, mobile wireless... 相似文献
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Three-dimensional (3D) YBO3:Tb3+ flower-like and dense flower-like hierarchitecture constituted of nanoflakes are solvothermally synthesized in the presence of polyborate precursors in the mixture of ethanol and water. The growth process of the YBO3:Tb3+ flowers and dense flowers was explored based on the time-dependent experiment and the results showed that the growth mechanism follows an in situ growth rather than self-assembly process as reported previously. YBO3:Tb3+ morphologies composed of nanoflakes are achieved by controlling the concentration of ethanol and dependence of photoluminescence on morphology was studied. Remarkable photoluminescence enhancement was observed for YBO3:Tb3+ with flower-like morphology demonstrating the potential of the microstructure in future applications as a green phosphor. Such a synthetic method and growth mechanism may be applied to fabricate complex 3D architectures of other materials. 相似文献
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V Douzdjian SS Bhaskar PK Baliga KK Gugliuzza PR Rajagopalan 《Canadian Metallurgical Quarterly》1997,20(8):1310-1314
OBJECTIVE: The racial impact on graft outcome is not well defined in diabetic recipients. The purpose of this study is to analyze our experience with kidney-alone (A) and kidney-pancreas (KP) transplantation in type 1 diabetic recipients and evaluate the impact of racial disparity on outcome. RESEARCH DESIGN AND METHODS: The records of 217 kidney transplants (118 KA, 99 KP) performed on type 1 diabetic patients between 1985 and 1995 at the Medical University of South Carolina and the University of Texas Medical Branch were reviewed. RESULTS: A total of 53 (31%) white patients and 15 (33%) black patients experienced at least one episode of biopsy-proven acute rejection of the renal graft (NS). Patient survival at 1, 2, and 5 years was similar in white (92, 87, 69%) and black (91, 91, 69%) patients (NS). Kidney graft survival at 1, 2, and 5 years in the KA group was 72, 62, and 42% in blacks, compared with 79, 76, and 53% in whites (NS). Kidney graft survival at 1, 2, and 5 years in the KP group was 92, 92, and 74% in blacks, compared with 83, 77, and 58% in whites (NS). Pancreas graft survival at 1, 2, and 5 years was 81, 81, and 81% in blacks, compared with 81, 75, and 62% in whites (NS). Cox regression analysis revealed that donor age > or = 40 years increased the risk of renal graft failure 6.2-fold (P = 0.0001), whereas the addition of a pancreas transplant to a kidney and a living-related transplant decreased the risk of failure of the kidney graft 0.2 (P = 0.005) and 0.1 times (P = 0.005). CONCLUSIONS: Our results suggest that when compared with whites, there may be a trend toward an improved kidney and pancreas graft outcome in blacks undergoing KP transplants. These findings suggest that diabetes may override the risk factors that account for the pronounced disparity in outcome observed between nondiabetic white and black recipients. 相似文献
6.
A hitherto unavailable analytical solution to the free vibration problem of general cross-ply laminated rigidly clamped rectangular plates, incorporating first-order shear deformation, and rotatory and in-plane inertias into the formulation, is presented. A recently developed boundary continuous displacement-based generalized Navier solution technique is used to solve the five highly coupled linear second-order partial differential equations with constant coefficients, and the associated geometric boundary conditions. The assumed solution functions are in the form of double Fourier series, which satisfy the rigidly clamped boundary conditions a priori in a manner similar to the conventional Navier method. Convergence characteristics of the natural frequencies of both symmetric and antisymmetric cross-ply plates are numerically established. Other numerical results presented herein include (i) comparison with the corresponding available first-order shear deformation theory-based Galerkin and classical lamination theory-based boundary-discontinuous analytical solutions, and (ii) study of the effects of thickness and aspect ratio on the natural frequencies. 相似文献
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Solutions, within the framework of linear uncoupled thermoelasticity, are presented for certain problems of flexure of composite laminates. Benchmark numerical results, useful for the validation or otherwise of approximate laminate models, are tabulated. Finally, these results are used to examine the accuracy of the classical lamination theory based on Kirchhoff's hypothesis. 相似文献
8.
Yousefi M. Chaudhuri S.K. Safavi-Naeini S. 《Antennas and Propagation, IEEE Transactions on》1994,42(1):38-46
Dielectric resonators (DR's) are widely used in telecommunication systems. A method is proposed here to find the resonant frequency and field distribution in a substrate-mounted DR structure. The field of a dielectric rod has been decomposed into a combination of guided modes with unknown coefficients and an unknown continuous spectrum of radiation field. The unknowns are then obtained by applying two generalized impedance boundary conditions (GIBC's) representing the substrate and air layers at the top and bottom of the DR. This leads to the calculation of the total (guided+radiation) field as well as the resonant frequency of the structure 相似文献
9.
Poor-grade fireclay products contain substantial amount of glass. A glass of similar composition was synthesized, nucleated
and heat-treated for crystallization of mullite. The size and size-distribution of mullite crystals, the rate of change of
size and the aspect ratio of the crystals were investigated in relation to the nucleating agents and temperature. 相似文献
10.
Ying Wang Chaudhuri S.K. Safavi-Naeini S. 《Antennas and Propagation, IEEE Transactions on》2002,50(11):1598-1604
A novel method of studying wave penetration through inhomogeneous walls using the hybrid technique based on combining finite-difference time-domain (FDTD) and ray tracing methods is presented . The FDTD method is used to analyze the transmission characteristics of inhomogeneous walls. Using the knowledge of the tangential electric and magnetic field distributions along the borders of the FDTD computation domain, rays are sent out to cover the rest of the environment so that prediction of signal coverage can be made more efficiently without compromising the accuracy. Numerical results of the method have been compared and shown to agree very well with those of measurement and those of full wave analysis. Examples have shown the inadequacy of the traditional ray tracing method in the presence of walls made of concrete blocks. However, the proposed method can accurately predict signal coverage by taking into account the scattered fields by the inhomogeneity inside the walls. The method does not add much to computational complexity. Reduction in computation time is even more significant when the incident waves can be approximated to be plane waves and the wall structure is periodic. 相似文献