Design,realization,and test of a monolithic GaAs 3bit phase digitizing DAC for 3bit digital radio-frequency memory are detailedly described.The 0.5μm fully ion-implanted GaAs MESFET is used to fabricate the circuit ...Design,realization,and test of a monolithic GaAs 3bit phase digitizing DAC for 3bit digital radio-frequency memory are detailedly described.The 0.5μm fully ion-implanted GaAs MESFET is used to fabricate the circuit in Nanjing Electronic Devices Institute’s (NEDI’s) 75mm standard process line.The high-speed DAC is designed with on-wafer 50Ω I/O impedance matching.Test results show that its work bandwidth is more than 1.5GHz,and phase accuracy is better than 4%.Its code conversion rate can be higher than 12Gbps.展开更多
Although the modified Goldstein filter based on the local signal-to-noise （SNR） has been proved to be superior to the classical Goldstein and Baran filters with more comprehensive filter parameter, its adaptation is...Although the modified Goldstein filter based on the local signal-to-noise （SNR） has been proved to be superior to the classical Goldstein and Baran filters with more comprehensive filter parameter, its adaptation is not always sufficient in the reduction of phase noise. In this work, the local SNR-based Goldstein filter is further developed with the improvements in the definition of the local SNR and the adaption of the filtering patch size. What＇s more, for preventing the loss of the phase signal caused by the excessive filtering, an iteration filtering operation is also introduced in this new algorithm. To evaluate the performance of the proposed algorithm, both a simulated digital elevation model （DEM） interferogram and real SAR deformation interferogram spanning the L＇ Aquila earthquake are carried out. The quantitative results from the simulated and real data reveal that up to 79.5% noises can be reduced by the new filter, indicating 9%-32% improvements over the previous local SNR-based Goldstein filter. This demonstrates that the new filter is not only equipped with sufficient adaption, but also can suppress the phase noise without the sacrifice of the phase signal.展开更多
Using the method of numerical matrix diagonalization within the effective-mass approximation, we investigated a D^--center quantum dot system subjected to a Gaussian potential confinement. We obtain the dependence of ...Using the method of numerical matrix diagonalization within the effective-mass approximation, we investigated a D^--center quantum dot system subjected to a Gaussian potential confinement. We obtain the dependence of binding energies of the ground-states of the D^--center on the depth of Gaussian potential and the magnetic field strength. The result shows clearly that the binding energies of the ground-states of the D^--center are rather sensitive to the depth of potential and the strength of magnetic field.展开更多
Using the recent compilation of the isotopic composition data of surface snow of Antarctic ice sheet, we proposed an improved interpolation method of δD, which utilizes geographical factors （i.e., latitude and altit...Using the recent compilation of the isotopic composition data of surface snow of Antarctic ice sheet, we proposed an improved interpolation method of δD, which utilizes geographical factors （i.e., latitude and altitude） as the primary predictors and incorporates inverse distance weighting （IDW） technique. The method was applied to a high-resolution digital elevation model （DEM） to produce a grid map of multi-year mean δD values with lkm spatial resolution for Antarctica. The mean absolute deviation between observed and estimated data in the map is about 5.4‰, and the standard deviation is 9‰. The resulting δD pattern resembles well known characteristics such as the depletion of the heavy isotopes with increasing latitude and distance from coast line, but also reveals the complex topographic effects.展开更多
In this paper,we propose a novel vision navigation method based on three-dimensional(3D)reconstruction from real-time image sequences.It adapts 3D reconstruction and terrain matching to establish the correspondence be...In this paper,we propose a novel vision navigation method based on three-dimensional(3D)reconstruction from real-time image sequences.It adapts 3D reconstruction and terrain matching to establish the correspondence between image points and3D space points and the terrain reference(by using a digital elevation map(DEM)).An adaptive weighted orthogonal iterative pose estimation method is employed to calculate the position and attitude angle of the aircraft.Synthesized and real experiments show that the proposed method is capable of providing accurate navigation parameters for a long-endurance flight without using a global positioning system or an inertial navigation system(INS).Moreover,it can be combined with an INS to achieve an improved navigation result.展开更多
文摘Design,realization,and test of a monolithic GaAs 3bit phase digitizing DAC for 3bit digital radio-frequency memory are detailedly described.The 0.5μm fully ion-implanted GaAs MESFET is used to fabricate the circuit in Nanjing Electronic Devices Institute’s (NEDI’s) 75mm standard process line.The high-speed DAC is designed with on-wafer 50Ω I/O impedance matching.Test results show that its work bandwidth is more than 1.5GHz,and phase accuracy is better than 4%.Its code conversion rate can be higher than 12Gbps.
基金Foundation item： Projects（40974006, 40774003） supported by the National Natural Science Foundation of China Project（NCET-08-0570） supported by the Program for New Century Excellent Talents in Universities of China+2 种基金 Proj ect（2011JQ001） supported by the Fundamental Research Funds for the Central Universities of China Project（PolyU 5155/07E） supported by the Research Grants Council （RGC） of the Hong Kong Special Administrative Region, China Project（CX2011B 102） supported by the Doctoral Research Innovation of Hunan Province, China
文摘Although the modified Goldstein filter based on the local signal-to-noise （SNR） has been proved to be superior to the classical Goldstein and Baran filters with more comprehensive filter parameter, its adaptation is not always sufficient in the reduction of phase noise. In this work, the local SNR-based Goldstein filter is further developed with the improvements in the definition of the local SNR and the adaption of the filtering patch size. What＇s more, for preventing the loss of the phase signal caused by the excessive filtering, an iteration filtering operation is also introduced in this new algorithm. To evaluate the performance of the proposed algorithm, both a simulated digital elevation model （DEM） interferogram and real SAR deformation interferogram spanning the L＇ Aquila earthquake are carried out. The quantitative results from the simulated and real data reveal that up to 79.5% noises can be reduced by the new filter, indicating 9%-32% improvements over the previous local SNR-based Goldstein filter. This demonstrates that the new filter is not only equipped with sufficient adaption, but also can suppress the phase noise without the sacrifice of the phase signal.
基金Thc project supported by National Natural Science Foundation of China under Grant Nos. 10475021 and 10275014
文摘Using the method of numerical matrix diagonalization within the effective-mass approximation, we investigated a D^--center quantum dot system subjected to a Gaussian potential confinement. We obtain the dependence of binding energies of the ground-states of the D^--center on the depth of Gaussian potential and the magnetic field strength. The result shows clearly that the binding energies of the ground-states of the D^--center are rather sensitive to the depth of potential and the strength of magnetic field.
基金Under the auspices of National Natural Science Foundation of China (No. 40825017, 40576001)100 Talents Project of Chinese Academy of SciencesNational Key Technologies R&D Program of China (No. 2006BAB18B01)
文摘Using the recent compilation of the isotopic composition data of surface snow of Antarctic ice sheet, we proposed an improved interpolation method of δD, which utilizes geographical factors （i.e., latitude and altitude） as the primary predictors and incorporates inverse distance weighting （IDW） technique. The method was applied to a high-resolution digital elevation model （DEM） to produce a grid map of multi-year mean δD values with lkm spatial resolution for Antarctica. The mean absolute deviation between observed and estimated data in the map is about 5.4‰, and the standard deviation is 9‰. The resulting δD pattern resembles well known characteristics such as the depletion of the heavy isotopes with increasing latitude and distance from coast line, but also reveals the complex topographic effects.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2013CB733100)
文摘In this paper,we propose a novel vision navigation method based on three-dimensional(3D)reconstruction from real-time image sequences.It adapts 3D reconstruction and terrain matching to establish the correspondence between image points and3D space points and the terrain reference(by using a digital elevation map(DEM)).An adaptive weighted orthogonal iterative pose estimation method is employed to calculate the position and attitude angle of the aircraft.Synthesized and real experiments show that the proposed method is capable of providing accurate navigation parameters for a long-endurance flight without using a global positioning system or an inertial navigation system(INS).Moreover,it can be combined with an INS to achieve an improved navigation result.
