990 resultados para 383


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A novel image restoration approach based on high-dimensional space geometry is proposed, which is quite different from the existing traditional image restoration techniques. It is based on the homeomorphisms and "Principle of Homology Continuity" (PHC), an image is mapped to a point in high-dimensional space. Begin with the original blurred image, we get two further blurred images, then the restored image can be obtained through the regressive curve derived from the three points which are mapped form the images. Experiments have proved the availability of this "blurred-blurred-restored" algorithm, and the comparison with the classical Wiener Filter approach is presented in final.

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This paper presents a novel fully integrated MOS AC to DC charge pump with low power dissipation and stable output for RFID applications. To improve the input sensitivity, we replaced Schottky-diodes in conventional charge pumps with MOS diodes with zero threshold, which has less process defects and is thus more compatible with other circuits. The charge pump in a RFID transponder is implemented in a 0.35um CMOS technology with 0.24 sq mm die size. The analytical model of the charge pump and the simulation results are presented.

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植物抗旱节水生物学是发展旱地农业和缺水区农业的重要学科基础,当前面临的主要问题包括:在研究路线上,如何正确处理分子水平研究与整体性研究之间的关系,以促进两者的互补;在研究目标上,如何做到抗旱性、水分利用效率、产量性状的有效结合,以实现高产高效;在研究成果应用中,如何切实加强学科交叉,以尽快取得实际效果。在论述上述问题的同时,对当前半干旱和半湿润地区与抗旱节水生物学有关的几个实践中的科技难点作了介绍,并提出建议。

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采用人工模拟降雨试验,研究水文条件对紫色土坡面土壤侵蚀及氮和磷养分流失的影响。试验处理包括2个施肥水平(低肥和高肥水平),4个水文条件(自由下渗、土壤水分饱和、壤中流、壤中流+降雨)和一个降雨强度(60 mm/h,历时60 min)。结果表明:壤中流+降雨和土壤水分饱和条件下的土壤侵蚀量分别是自由下渗条件下的3.1和1.7倍,同自由下渗相比,壤中流、壤中流+降雨和土壤水分饱和条件下,地表径流中NO3-N、HPO4-P的浓度和流失量有显著增加;低肥水平条件下,自由下渗、土壤水分饱和、壤中流和壤中流+降雨地表径流中,NO3-N的浓度分别是0.88、58.90、698.41和87.80 mg/L,对应水文条件下地表径流中,HPO4-P的浓度分别是0.252、0.322、0.811和0.383 mg/L,高肥水平条件下,径流中的NO3-N和HPO4-P的浓度也有相同的趋势;土壤水分饱和条件下,地表径流中NO3-N和HPO4-P的流失量分别是自由下渗条件下的27~39和1.3倍,壤中流+降雨条件下,地表径流中NO3-N和HPO4-P的流失量分别是自由下渗条件下的100~114和1.5~1.7倍,同时,壤中流+降雨和土壤...

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采用人工模拟降雨实验,研究了近地表土壤水分条件,尤其是土壤水分饱和条件对土壤侵蚀过程中农业非点源污染物运移的影响.结果表明,前期近地表土壤水分条件对土壤侵蚀过程中农业非点源污染物的迁移有着很大影响.饱和含水量时径流及泥沙中非点源污染物的流失浓度和流失量大于非饱和含水量,且前期近地表土壤含水量越大,径流及泥沙中农业非点源污染物的流失浓度和流失量越大.土壤氮素的主要流失途径是降雨所产生的径流,约占总流失量的90.4%~99.8%;土壤磷素的流失途径是降雨径流和侵蚀产沙,分别占总流失量的2.67%~23.5%和76.5%~97.3%.同时,土壤质地对磷素养分的流失有很大影响,杨凌土随泥沙流失的DP浓度和流失量均大于安塞黄绵土.最后,提出了采取最佳管理措施等控制农业非点源污染的针对性建议.

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A comparatively low-quality silicon wafer (with a purity of almost-equal-to 99.9%) was adopted to form a silicon-on-defect-layer (SODL) structure featuring improved crystalline silicon near the defect layer (DL) by means of proton implantation and subsequent annealing. Thus, the SODL technique provides an opportunity to enable low-quality silicon wafers to be used for fabrication of low-cost solar cells.

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GaSb layers are grown on GaSb substrates; the effects of input partial pressure of trimethylantimony and the V/III ratio are studied. A model of the MOVPE phase diagram for the growth of GaSb and GaAsxSb1-x is developed which assumes thermodynamic equilibrium to be established at the solid-vapor interface.

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In this work we investigate the lateral periodicity of symmetrically strained (GaIn)As/GaAs/Ga(PAs)/GaAs superlattices by means of X-ray scattering techniques. The multilayers were grown by metalorganic Vapour phase epitaxy on (001)GaAs substrates, which were intentionally off-oriented towards the [011]-direction. The substrate off-orientation and the strain distribution was found to affect the structural properties of the superlattices inducing the generation of laterally ordered macrosteps. Several high-resolution triple-crystal reciprocal space maps, which were recorded for different azimuth angles in the vicinity of the (004) Bragg diffraction and contour maps of the specular reflected beam collected in the vicinity of the (000) reciprocal lattice point, are reported and discussed. The reciprocal space maps clearly show a two-dimensional periodicity of the X-ray peak intensity distribution which can be ascribed to the superlattice periodicity in the direction of the surface normal and to a lateral periodicity in a crystallographic direction coinciding with the miscut orientation. The distribution and correlation of the vertical as well as of the lateral interface roughness was investigated by specular reflectivity and diffuse scattering measurements. Our results show that the morphology of the roughness is influenced by the off-orientation angle and can be described by a 2-dimensional waviness.