A new beam broadening synthesis technique for Synthetic Aperture Radar(SAR) antenna array, namely Projection Matrix Algorithm(PMA) is presented. The theory of PMA is introduced firstly, and then the iterative renewed ...A new beam broadening synthesis technique for Synthetic Aperture Radar(SAR) antenna array, namely Projection Matrix Algorithm(PMA) is presented. The theory of PMA is introduced firstly, and then the iterative renewed manner is improved to resolve the unbalance problem under amplitude and phase control. In order to validate the algorithm correct and effective, an actual engineering application example is investigated. The beam synthesis results of 1.0~4.5 times broadening under the phase only control and the amplitude and phase control using improved PMA are given. The results show that the beam directivity, the beam broadening, and the side-lobe level requirements were met. It is demonstrated that the improved PMA was effective and feasible for SAR application.展开更多
The bandwidth characteristic of phased array antenna can be represented by the extent of beam broadening as signal bandwidth is increased. By using two kinds of bandpass signals, the beam 3dB-width values for a variet...The bandwidth characteristic of phased array antenna can be represented by the extent of beam broadening as signal bandwidth is increased. By using two kinds of bandpass signals, the beam 3dB-width values for a variety of instantaneous bandwidths in conventional phased array and wide band optically phased array are respectively analyzed and simulated based on both of their models. And some corresponding curves are given.展开更多
Mn segregation at austenite/ferrite interface is studied in a Fe-C-Mn-Si alloy held at 656℃. Mn is partitioned during the growth of ferrite and as a result, a Mn pile-up exists in front of interface on the matrix sid...Mn segregation at austenite/ferrite interface is studied in a Fe-C-Mn-Si alloy held at 656℃. Mn is partitioned during the growth of ferrite and as a result, a Mn pile-up exists in front of interface on the matrix side. An approach to evaluate Mn segregation quantitatively is developed by combining STEM raster window scanning and simulation of the interaction of the electron beam with the sample to subtract the contribution of Mn pile-up and obtain pure Mn segregation value. The evaluated maximum Mn interfacial segregation is in the order of a half-monolayer.展开更多
The beam must be extracted into the air through the vacuum window to irradiate the living cell.In the window design,the material and thickness must be chosen to compromise the beam spot size broadening and the window ...The beam must be extracted into the air through the vacuum window to irradiate the living cell.In the window design,the material and thickness must be chosen to compromise the beam spot size broadening and the window safety.The structure-static analysis on the window of different structures and materials is done with the finite element analysis method,and the deformation and the equivalent stress are simulated.The safety of these candidates is investigated using the intensity theory.In addition,the small angle scattering and the transverse range of ions are simulated using SRIM code,including all the effects on the beam spot size broadening,such as the incident ion energy, the material and the thickness of the window and the air composing.At last,the appropriate vacuum windows are presented,including the structure,material and thickness.展开更多
文摘A new beam broadening synthesis technique for Synthetic Aperture Radar(SAR) antenna array, namely Projection Matrix Algorithm(PMA) is presented. The theory of PMA is introduced firstly, and then the iterative renewed manner is improved to resolve the unbalance problem under amplitude and phase control. In order to validate the algorithm correct and effective, an actual engineering application example is investigated. The beam synthesis results of 1.0~4.5 times broadening under the phase only control and the amplitude and phase control using improved PMA are given. The results show that the beam directivity, the beam broadening, and the side-lobe level requirements were met. It is demonstrated that the improved PMA was effective and feasible for SAR application.
基金Supported by National Defence Pre-research Project of "Tenth Five-Year-Plan" of China
文摘The bandwidth characteristic of phased array antenna can be represented by the extent of beam broadening as signal bandwidth is increased. By using two kinds of bandpass signals, the beam 3dB-width values for a variety of instantaneous bandwidths in conventional phased array and wide band optically phased array are respectively analyzed and simulated based on both of their models. And some corresponding curves are given.
基金supported by the National Natural Science Foundation of China under grant No. 50601002the Scientific Research Foundation for the Returned Over-seas Chinese Scholars, State Education Ministry
文摘Mn segregation at austenite/ferrite interface is studied in a Fe-C-Mn-Si alloy held at 656℃. Mn is partitioned during the growth of ferrite and as a result, a Mn pile-up exists in front of interface on the matrix side. An approach to evaluate Mn segregation quantitatively is developed by combining STEM raster window scanning and simulation of the interaction of the electron beam with the sample to subtract the contribution of Mn pile-up and obtain pure Mn segregation value. The evaluated maximum Mn interfacial segregation is in the order of a half-monolayer.
文摘The beam must be extracted into the air through the vacuum window to irradiate the living cell.In the window design,the material and thickness must be chosen to compromise the beam spot size broadening and the window safety.The structure-static analysis on the window of different structures and materials is done with the finite element analysis method,and the deformation and the equivalent stress are simulated.The safety of these candidates is investigated using the intensity theory.In addition,the small angle scattering and the transverse range of ions are simulated using SRIM code,including all the effects on the beam spot size broadening,such as the incident ion energy, the material and the thickness of the window and the air composing.At last,the appropriate vacuum windows are presented,including the structure,material and thickness.
