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901.
902.
自然背景下人工目标的检测与分割 总被引:8,自引:1,他引:7
在分水岭分割算法的基础上 ,提出基于模糊逻辑理论的集水盆合并方法 ,对自然背景下人工目标的检测与分割以及自然背景的抑制与消除进行了探讨和研究。 相似文献
903.
P. W. M. Tsang W. T. Lee 《Journal of Visual Communication and Image Representation》2000,11(4):343-359
A novel image compression scheme based on two-dimensional adaptive decimation is reported in this paper. In this approach, images are encoded with adaptive sampling along the horizontal and vertical directions, and decoded with an edge prediction interpolation algorithm. The method is capable of maintaining reasonable coding fidelity at low bit-rate with good visual quality. As only a small amount of computation is required in the encoding and decoding processes, the compression scheme can be implemented for real time operation with simple hardware and a small amount of memory storage. The proposed scheme had been applied in encoding images at bit-rates between 0.2 and 0.33 bpp and the results are encouraging. 相似文献
904.
发射极电流集边效应理论的SPICE模拟验证 总被引:4,自引:0,他引:4
发射极电流集边效应是由晶体管基极电阻的自偏压引起的 ,描述该效应的微分方程早已建立 ,这里设计了一种用 SPICE验证精确解 /近似解的新方法 .结果表明 :近似解是在 V( x) VT 的前提条件下求得的 ,仅在弱注入区和中等注入区适用 ,不能给出在强注入区和极强注入区的归一化电位和电流密度的分布函数 ;相反 ,基于精确解的理论却能给出从弱注入区到极强注入区的归一化电位和电流密度的分布函数 ,且与用 SPICE模拟得到的结果吻合 .结论是 :从整体来看 ,精确解的理论比近似解的理论描述该效应要稍好一些 ,因为前者的适用范围比后者宽 .应当强调指出 ,该效应 相似文献
905.
X-ray absorption near the edge structure and x-ray photoelectron spectroscopy studies on pyrite prepared by thermally sulfurizing iron films
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This paper reports how pyrite films were prepared by thermal
sulfurization of magnetron sputtered iron films and characterized by
x-ray absorption near edge structure spectra and x-ray photoelectron
spectroscopy on a 4B9B beam line at the Beijing Synchrotron Radiation
Facility. The band gap of the pyrite agrees well with the optical
band gap obtained by a spectrophotometer. The octahedral symmetry of
pyrite leads to the splitting of the d orbit into t_{\rm 2g} and
e_{\rm g} levels. The high spin and low spin states were analysed
through the difference of electron exchange interaction and the orbital
crystal field. Only when the crystal field splitting is higher than
1.5 eV, the two weak peaks above the white lines can appear, and this
was approved by experiments in the present work. 相似文献
906.
Influence of dislocations in the GaN layer on the electrical properties of an AlGaN/GaN heterostructure
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This paper reports on a comparative study of the spatial
distributions of the electrical, optical, and structural properties
in an AlGaN/GaN heterostructure. Edge dislocation density in the GaN
template layer is shown to decrease in the regions of the wafer
where the heterostructure sheet resistance increases and the GaN
photoluminescence band-edge energy peak shifts to a high wavelength.
This phenomenon is found to be attributed to the local compressive
strain surrounding edge dislocation, which will generate a local
piezoelectric polarization field in the GaN layer in the opposite
direction to the piezoelectric polarization field in the AlGaN layer and
thus help to increase the two-dimensional electron gas
concentration. 相似文献
907.
A. Saitoh 《Journal of Raman spectroscopy : JRS》2007,38(5):537-542
Raman scattering from BiI3 and SbI3 crystals has been studied at hydrostatic pressures up to 2 GPa. The wavenumbers monotonically increased with pressure for all modes in BiI3. Although both crystals belong to the same space group, the pressure coefficients of SbI3 were significantly different from those of BiI3. At pressure P0 = 0.92 ± 0.01 GPa, the pressure coefficients of all modes changed. Above P0, all modes in SbI3 had positive pressure coefficients as they have in BiI3. By comparing this unusual behavior of the Raman lines in SbI3 around P0 with the results in BiI3 and comparing the two lattice structures, we suggest that the type of bonding of SbI3 changes to become more ionic and hence more similar to the bonding of BiI3. This change in structure is supported by changes in the bandwidth of the self‐trapped exciton (STE) luminescence and the slope of the absorption edge photon energy versus pressure. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
908.
909.
910.
By means of Delta-function & unit step function to express the force of solid particle on plane inertial shaker’s screen, an mathematical model of the differential equation type was set up and solved. According to analysis of the solution, the relation is given between the throw period & displacement with the parameters of shaker design & solid particle. The method of numerical value calculation & analysis for the relation is given too. 相似文献