In order to improve the identification capability of ultra wide-band radar,this paper in-troduces a step-variant multiresolution approach for the time-shift parameter estimation. Subsequently,combining with the approa...In order to improve the identification capability of ultra wide-band radar,this paper in-troduces a step-variant multiresolution approach for the time-shift parameter estimation. Subsequently,combining with the approach,a Geometrical Theory of Diffraction(GTD) model-based time-shift Invariant method to target identification using Matching Pursuits and Likelihood Ratio Test(IMPLRT) is developed. Simulation results using measured scattering signatures of two targets in an ultra wide-band chamber are presented contrasting the performance of the IMPLRT to the Wang's MPLRT technique.展开更多
By means of electron backscattering diffraction and transmission electron microscopy the microstructure and texture of drawn single crystal copper with initial orientation （110） parallel to axial direction have been...By means of electron backscattering diffraction and transmission electron microscopy the microstructure and texture of drawn single crystal copper with initial orientation （110） parallel to axial direction have been investigated in the present work. In or- der to analyze the effect of initial orientation on microstructure and texture of drawn copper, the results of the drawn （110） sin- gle crystal copper wires have been compared with （100） and （111） single crystal copper wires. It is found that the grain subdi- vision of （110） single crystal is more evident than that of （100） and （111）, and the textures consisting of （111） and （100） abruptly form in the drawn （110） single crystal. At high strains, due to shear strain, the distribution of fiber textures is imho- mogenous along the radial direction of drawn （110） single crystal copper wires. （100） is near the surface and （111） is at the center. The microstructure results of drawn （110） single crystal show that at low strains, it can be characterized as two kinds of geometrically necessary boundaries with noncrystalline character. At medium strains, S bands can be observed. At high strains, lamellar boundaries form. Mean misofientation and average spacing of dislocation boundary are larger in drawn （110） single crystal, as compared with （111） and （100）. In drawn （110） single crystal with high strains, the bimodal distribution forms at lower strains than in drawn （100） single crystal, which is because the dislocation boundaries with high angle are contributed by not only the boundary between （111） and （100） fiber textures but also the boundary in （111） or （100） texture.展开更多
In order to satisfy the demands for diffractive telescopes in space exploration, a new deployable space diffractive tele- scope is designed. The structure and geometrical sizes of the spontaneously deployable telescop...In order to satisfy the demands for diffractive telescopes in space exploration, a new deployable space diffractive tele- scope is designed. The structure and geometrical sizes of the spontaneously deployable telescope are preliminarily designated through the Serrurier truss principle and the optimized design theory. The finite element model of the de- ployable structure is established, and its deployed characteristics are analyzed. The prototype of the spontaneously de- ployable structure is constructed and some experiments are carried out to study its characteristics. Experimental results indicate that the deployable structure is 2.95 m in length, its repetitive deployed precision can reach less than 2 ram, the off-center error is less than 0.3 mm, and its deployed precision can be adjusted to micrometer level by actuators when it has deployed. It has simple structure, low mass, steady and reliable deployment, as well as higher precision for space diffractive telescopes.展开更多
Salts containing aniline radical cations have been isolated and characterized by electron paramagnetic resonance(EPR)spectroscopy, UV-Vis absorption spectroscopy and single crystal X-ray diffraction. The EPR spectra a...Salts containing aniline radical cations have been isolated and characterized by electron paramagnetic resonance(EPR)spectroscopy, UV-Vis absorption spectroscopy and single crystal X-ray diffraction. The EPR spectra and theoretical calculations indicate the unpaired electron is delocalized on phenyl rings and nitrogen atoms. Both radical cations feature a quinoidal geometry with a partially double C–N bond, but are distinct in that the C–N bond is coplanar to the phenyl plane in one cation while deviates from the plane in the other due to steric crowding. The work provides the first unequivocal examples of stable aniline radical cations.展开更多
文摘In order to improve the identification capability of ultra wide-band radar,this paper in-troduces a step-variant multiresolution approach for the time-shift parameter estimation. Subsequently,combining with the approach,a Geometrical Theory of Diffraction(GTD) model-based time-shift Invariant method to target identification using Matching Pursuits and Likelihood Ratio Test(IMPLRT) is developed. Simulation results using measured scattering signatures of two targets in an ultra wide-band chamber are presented contrasting the performance of the IMPLRT to the Wang's MPLRT technique.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50901055, 50771076)the Education Department Foundation of Shanxi Province, China (Grant No. 07JK274)
文摘By means of electron backscattering diffraction and transmission electron microscopy the microstructure and texture of drawn single crystal copper with initial orientation （110） parallel to axial direction have been investigated in the present work. In or- der to analyze the effect of initial orientation on microstructure and texture of drawn copper, the results of the drawn （110） sin- gle crystal copper wires have been compared with （100） and （111） single crystal copper wires. It is found that the grain subdi- vision of （110） single crystal is more evident than that of （100） and （111）, and the textures consisting of （111） and （100） abruptly form in the drawn （110） single crystal. At high strains, due to shear strain, the distribution of fiber textures is imho- mogenous along the radial direction of drawn （110） single crystal copper wires. （100） is near the surface and （111） is at the center. The microstructure results of drawn （110） single crystal show that at low strains, it can be characterized as two kinds of geometrically necessary boundaries with noncrystalline character. At medium strains, S bands can be observed. At high strains, lamellar boundaries form. Mean misofientation and average spacing of dislocation boundary are larger in drawn （110） single crystal, as compared with （111） and （100）. In drawn （110） single crystal with high strains, the bimodal distribution forms at lower strains than in drawn （100） single crystal, which is because the dislocation boundaries with high angle are contributed by not only the boundary between （111） and （100） fiber textures but also the boundary in （111） or （100） texture.
基金supported by the National High Technology and Development Program of China(No.2015AA7015090)the National Science and Technology Major Project of China(No.2016YFB0501202)
文摘In order to satisfy the demands for diffractive telescopes in space exploration, a new deployable space diffractive tele- scope is designed. The structure and geometrical sizes of the spontaneously deployable telescope are preliminarily designated through the Serrurier truss principle and the optimized design theory. The finite element model of the de- ployable structure is established, and its deployed characteristics are analyzed. The prototype of the spontaneously de- ployable structure is constructed and some experiments are carried out to study its characteristics. Experimental results indicate that the deployable structure is 2.95 m in length, its repetitive deployed precision can reach less than 2 ram, the off-center error is less than 0.3 mm, and its deployed precision can be adjusted to micrometer level by actuators when it has deployed. It has simple structure, low mass, steady and reliable deployment, as well as higher precision for space diffractive telescopes.
基金supported by National Natural Science Foundation of China (21171087)the Natural Science Foundation of Jiangsu Province (BK20140014)
文摘Salts containing aniline radical cations have been isolated and characterized by electron paramagnetic resonance(EPR)spectroscopy, UV-Vis absorption spectroscopy and single crystal X-ray diffraction. The EPR spectra and theoretical calculations indicate the unpaired electron is delocalized on phenyl rings and nitrogen atoms. Both radical cations feature a quinoidal geometry with a partially double C–N bond, but are distinct in that the C–N bond is coplanar to the phenyl plane in one cation while deviates from the plane in the other due to steric crowding. The work provides the first unequivocal examples of stable aniline radical cations.
