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排序方式: 共有444条查询结果,搜索用时 453 毫秒
41.
LiuGuangyan HuangShunji 《电子科学学刊(英文版)》2003,20(5):337-343
Instantaneous Doppler frequency for squint SAR imaging has been found with Chirp Scaling Algorithm (CSA). Because the azimuth sample is not perpendicular to the range sample,the range signal must impact on the azimuth signal in the squint SAR data processing, and the different slant range targets have different Doppler frequencies. From the mathematical model of SAR echo signal, this paper carefully analyzes the instantaneous azimuth frequency, the instantaneous Doppler frequency component of the azimuth frequency and the impact of range chirp on azimuth frequency, which explains that Doppler frequency should be properly selected for correct SAR imaging in the squint SAR. The results of point target simulation experiments show that the way is reasonable for the squint SAR and can effectively complete range compression and azimuth focusing, and improve images‘ quality. 相似文献
42.
网格编码矢量量化在SAR原始数据压缩中的应用 总被引:1,自引:0,他引:1
本文提出了一种结合传统的块自适应量化与网格编码矢量量化对SAR原始数据进行压缩的方法。首先对SAR原始数据实施块自适应量化以减小数据的动态范围,然后对块自适应量化后的数据进行网格编码矢量量化。该方法在考虑了SAR原始数据特性的基础上较好地利用了矢量的空间相关性和信号的时间相关性,进一步提高了量化增益。仿真结果表明,该方法在SAR原始数据的压缩中取得了很好的效果。 相似文献
43.
44.
Lianzhou Wang S. Velu S. Tomura F. Ohashi K. Suzuki M. Okazaki T. Osaki M. Maeda 《Journal of Materials Science》2002,37(4):801-806
A new series of mesoporous silica spheres containing nanodispersed copper oxides were synthesized in H2O/EtOH/ammonia solution at room temperature. The mesoporous structures were characterised using X-ray powder diffraction and N2 adsorption-desorption techniques. Scanning electron micrograph and transmission electron micrograph revealed that the MCM-41 particles have spherical morphologies. The DTA curve of pure MCM-41 exhibited a sharp single exothermic peak between 290°C and 340°C, while a broad peak with several shoulders in the temperature range between 180°C and 380°C was observed for Cu-MCM-41, indicating the possible complexation of Cu2+ with surfactants adhering to the inner surfaces of the mesopores. Electron paramagnetic resonance spectra of uncalcined samples revealed that Cu2+ ions are in an octahedral or distorted octahedral coordination with nitrogen ligands of the surfactant while in the calcined samples they are coordinated with oxygen of the MCM-41 framework. The redox properties of samples were examined by a temperature-programmed reduction and N2O passivation method. The results indicate that CuO with increasing particle size could be formed in the mesoporous materials with increasing Cu contents, and this decreased the reducibility of the resulting CuO. 相似文献
45.
Hirokazu Osaki 《Computers & Industrial Engineering》1994,27(1-4):331-334
In this paper, we propose the intelligential industrial management which is the new concept in the industrial management. In the intelligential industrial management, the know-how and experience in the production process are divided into the fact, relation, and action in whit many criteria are used. The rule is constructed from the relation and action. And the inference process shows the sequence of the action and rule by using the inference symbol proposed. 相似文献
46.
47.
An artificial dermis product was applied to full-thickness skin defects in rats and cell infiltration into the collagen matrix was investigated. Host fibroblasts and capillaries infiltrated as far as the upper end of the collagen matrix by day 14 after application. Determination of glycosaminoglycan levels in the matrix showed that hyaluronic acid was generated in a similar amount to that seen in the intact skin by day 14. An autologous thin split-thickness skin graft was placed onto the artificial dermis simultaneously or several days after its application to the defect. The take rate was 100% when a split-thickness skin graft was performed on day 14 after application of the artificial dermis. At 6 weeks after the skin defect was created, the wound area was 80% of the original area and the dermis at the grafted site was as thick as that of normal skin. These results suggested that the artificial dermis provides a good matrix for thin split-thickness skin graft and is useful for the reconstruction of full-thickness skin defects. This method is considered to be an alternative to the conventional procedure using thick skin grafts or skin flaps. 相似文献
48.
In this paper, a new maximum likelihood (ML) classification algorithm is proposed to classify the multi-look polarimetric synthetic aperture radar (SAR) imagery. Experimental results with the NASA/JPL airborne L-band polarimetric SAR data demonstrate the effectiveness of the new algorithm. Furthermore, when using the algorithm in the classifications with subsets of the multi-look polarimetric SAR data, the polarization-channel optimization for the terrain type classification is implemented. 相似文献
49.
Aoi Sugiyama Shunji Araki Naonori Sakamoto Tomoaki Watanabe Masahiro Yoshimura 《Journal of Electroceramics》2006,17(1):71-74
Ceramics have generally been fabricated from powders by shape forming & sintering methods except for glasses and glass ceramics.
Glasses and glass ceramics can be fabricated by melting methods. The melting method has not only higher productivity but also
higher shape forming ability than powder processes via forming & sintering methods. Thus we have reinvestigated melting methods
in binary and ternary oxides systems to fabricate amorphous bulk ceramics and bulk nano composites. We have successfully fabricated
amorphous phases by simple melt solidification methods in ternary eutectic melts in the HfO2-Al2O3-Gd2O3system. The present study demonstrates the formation of the amorphous phases in quaternary systems HfO2-Al2O3-Gd2O3-Eu2O3. Furthermore, we have also succeeded to fabricate nano-structured bulk ceramics, which consisted of constituent oxide grains
with 20–100 nm in size, by post annealing of the amorphous phase. 相似文献
50.
线性调频连续波雷达的等效正交双通道性能 总被引:6,自引:0,他引:6
本文通过理论分析和实验研究,证明了线性调频连续波雷达可以用单通道获得等效的正交双通道性能,为简化相干线性调频连续波雷达的通道结构提供理论依据。 相似文献