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排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
Morton P.A. Ackerman D.A. Shtengel G.E. Kazarinov R.F. Hybertsen M.S. Tanbun-Ek T. Logan R.A. Sergent A.M. 《Photonics Technology Letters, IEEE》1995,7(8):833-835
We describe the important characteristics of high-speed p-doped compressively strained MQW lasers obtained from comprehensive below-threshold DC measurements. Results of gain and differential gain versus wavelength and carrier density are verified by above-threshold resonance measurements. Measurement-derived design curves of gain, differential gain, and linewidth enhancement factor allow device optimization for high speed and low chirp 相似文献
922.
Natural convections in conjugated single and double enclosures 总被引:7,自引:0,他引:7
The natural convection in single and double conjugated enclosures are numerically investigated. The single and double enclosures are formed by low conductance walls with finite thickness. The outside vertical surfaces of the conducting walls are of the third kind of boundary condition while the top and bottom outside surfaces are adiabatic. The problem studied is characterized by a dominant horizontal temperature gradient and the thermal boundary conditions at the cavity surfaces can not be specified in priori. Numerical results reveal the characteristics in such kind of enclosures and show the importance of the thermal boundary conditions on the natural convection in enclosures. It is also found that the natural convections in the conjugated double enclosures are basically the same, with a major difference in their fluid temperature levels. 相似文献
923.
Massively parallel computational paradigms can mitigate many issues associated with the analysis of large and complex remotely sensed data sets. Recently, the Beowulf cluster has emerged as the most attractive, massively parallel architecture due to its low cost and high performance. Whereas most Beowulf designs have emphasized numerical modeling applications, the Parallel Image Processing Environment (PIPE) specifically addresses the unique requirements of remote sensing applications. Automated, parallelization of user-defined analyses is fully supported. A neural network application, applied to Along Track Scanning Radiometer-2 (ATSR-2) data shows the advantages and performance characteristics of PIPE. 相似文献
924.
925.
A.Y. Vorobyev 《Applied Surface Science》2007,253(17):7272-7280
In this study we perform the first femtosecond laser surface treatment of titanium in order to determine the potential of this technology for surface structuring of titanium implants. We find that the femtosecond laser produces a large variety of nanostructures (nanopores, nanoprotrusions) with a size down to 20 nm, multiple parallel grooved surface patterns with a period on the sub-micron level, microroughness in the range of 1-15 μm with various configurations, smooth surface with smooth micro-inhomogeneities, and smooth surface with sphere-like nanostructures down to 10 nm. Also, we have determined the optimal conditions for producing these surface structural modifications. Femtosecond laser treatment can produce a richer variety of surface structures on titanium for implants and other biomedical applications than long-pulse laser treatments. 相似文献
926.
An eigenanalysis interference canceler 总被引:4,自引:0,他引:4
Eigenanalysis methods are applied to interference cancellation problems. While with common array processing methods the cancellation is effected by global optimization procedures that include the interferences and the background noise, the proposed technique focuses on the interferences only, resulting in superior cancellation performance. Furthermore, the method achieves full effectiveness even for short observation times, when the number of samples used for processing is of the the order of the number of interferences. Adaptive implementation is obtained with a simple, fast converging algorithm 相似文献
927.
928.
A. F. Semenchev V. G. Gavrilyachenko E. M. Kuznetsova E. N. Sklyarova 《Physics of the Solid State》2006,48(6):1146-1148
The details of the mechanical effects (twinning and microcracking) are clarified at various stages of dynamic fatigue of PbTiO3 crystals using a polarization microscope and selective etching. 相似文献
929.
Preparation and mechanical properties of layers made of recombinant spider silk proteins and silk from silk worm 总被引:1,自引:0,他引:1
F. Junghans M. Morawietz U. Conrad T. Scheibel A. Heilmann U. Spohn 《Applied Physics A: Materials Science & Processing》2006,82(2):253-260
Layers of recombinant spider silks and native silks from silk worms were prepared by spin-coating and casting of various solutions.
FT-IR spectra were recorded to investigate the influence of the different mechanical stress occurring during the preparation
of the silk layers. The solubility of the recombinant spider silk proteins SO1-ELP, C16, AQ24NR3, and of the silk fibroin
from Bombyx mori were investigated in hexafluorisopropanol, ionic liquids and concentrated salt solutions. The morphology and thickness of
the layers were determined by Atomic Force Microscopy (AFM) or with a profilometer. The mechanical behaviour was investigated
by acoustic impedance analysis by using a quartz crystal microbalance (QCMB) as well as by microindentation.
The density of silk layers (d<300 nm) was determined based on AFM and QCMB measurements. At silk layers thicker than 300 nm
significant changes of the half-band-half width can be correlated with increasing energy dissipation. Microhardness measurements
demonstrate that recombinant spider silk and sericine-free Bombyx mori silk layers achieve higher elastic penetration modules EEP and Martens hardness values HM than those of polyethylenterephthalate (PET) and polyetherimide (PEI) foils. 相似文献
930.
Nickel and cobalt films illustrate alternative Bloch lines with cap switches. The strip magnetic domains become zigzag and bubbling cells for Ni and Co films, respectively, under an external field of 1.5 T. The magnetoresistances (MR) for currents parallel (CIW) to the domain walls is 15% less than those of the perpendicular (CPW) case. We also studied the magneto size effect by applying the magnetic field normal to the surface, from which the Sondheimer oscillation appears attributing to periodic striking of the surface for electrons traveling in circular motion on a plane canting to the surface. The experiments can be expressed by the magneto size effect inherited with very small specularity parameters. 相似文献