稀疏多元逻辑回归(SMLR)是高光谱监督分类中的重要方法,然而仅仅利用光谱信息的SMLR忽略了影像本身的空间特征,在少量监督样本下的分类精度和算法的鲁棒性仍明显不足;虽然通过引入核技巧,核稀疏多元逻辑回归(KSMLR)可以部分克服上述缺点...稀疏多元逻辑回归(SMLR)是高光谱监督分类中的重要方法,然而仅仅利用光谱信息的SMLR忽略了影像本身的空间特征,在少量监督样本下的分类精度和算法的鲁棒性仍明显不足;虽然通过引入核技巧,核稀疏多元逻辑回归(KSMLR)可以部分克服上述缺点,其分类错误仍然有待进一步降低.本文基于核稀疏多元逻辑回归分类误差的统计建模分析,提出一种联合核稀疏多元逻辑回归和正则化错误剔除的高光谱图像分类模型.提出的模型通过引入隐概率场,采取L1范数度量KSMLR分类误差的重尾特性建立数据保真项;利用全变差(Total Variation,TV)正则化度量隐概率场的局部空间光滑性.由Indian Pines和University of Pavia数据集等实测数据应用表明,该方法可以得到更鲁棒和更高的分类精度.展开更多
根据一种X波段船舶导航雷达的总体技术指标,研制了一款与之配套的低噪声镜像抑制射频前端接收机。整个接收机由限幅、低噪声放大、镜像抑制混频三个主要功能模块构成。在研制过程中采取由独立到集成的研制思路,在每个独立模块的性能经...根据一种X波段船舶导航雷达的总体技术指标,研制了一款与之配套的低噪声镜像抑制射频前端接收机。整个接收机由限幅、低噪声放大、镜像抑制混频三个主要功能模块构成。在研制过程中采取由独立到集成的研制思路,在每个独立模块的性能经测试符合技术指标的基础上再进行整个接收机的集成设计及实验测试,给出了接收机的噪声及链路增益测试曲线。测试结果表明:该射频接收机在9.36 GHz^9.46 GHz频率范围内具有3.6 d B的噪声系数及2.5 d B的链路增益,镜像抑制度达到30 d B,各项性能指标均满足船舶导航雷达使用要求。整个前端模块体积小、成本低,适合民用领域的规模化生产。展开更多
针对机载设备小型化、轻量化、低功耗等要求,采用射频电路小型一体化技术、大功率发射等方法,设计了一种X波段低噪声系数、多次变频等功能的一体化收发组件。收发组件的主要指标噪声系数≤3 d B;镜像抑制≥50 d B;发射泄漏幅度在-10~0 d...针对机载设备小型化、轻量化、低功耗等要求,采用射频电路小型一体化技术、大功率发射等方法,设计了一种X波段低噪声系数、多次变频等功能的一体化收发组件。收发组件的主要指标噪声系数≤3 d B;镜像抑制≥50 d B;发射泄漏幅度在-10~0 d Bm;输出脉冲功率≥30 W。组件用于某雷达,已通过试验验证,性能稳定,具有较强实用性。展开更多
We present a method for detecting oil spills in a complex scene of SAR imagery,including segmenting oil spills,and avoiding false alarms.Segmentation is carried out using a multi-time and multi-hierarchical method by ...We present a method for detecting oil spills in a complex scene of SAR imagery,including segmenting oil spills,and avoiding false alarms.Segmentation is carried out using a multi-time and multi-hierarchical method by dividing the complex sea surface into bright sea and dark sea.Gray-based and edge-based segmentations are done to extract oil spills from bright and dark sea,respectively.The proposed method can extract complete oil spills,obtain better visual results,and increase detection probability more accurately than the traditional method.Based on the surrounding features and the oil spills’features,dark land spots and low contrast dark spots are removed efficiently,thus reducing false alarms.The experimental results demonstrate that the proposed algorithm has fast computation speed,high detection accuracy,and is very useful and effective for detecting oil spills in SAR imagery.展开更多
A 19 mW highly integrated GPS receiver with a ΣΔ fractional-N synthesizer is presented in this paper.Fractional-N frequency synthesizer architecture was adopted in this work, to provide more degrees of freedom in th...A 19 mW highly integrated GPS receiver with a ΣΔ fractional-N synthesizer is presented in this paper.Fractional-N frequency synthesizer architecture was adopted in this work, to provide more degrees of freedom in the synthesizer design.A high linearity low noise amplifier(LNA) is integrated into the chip.The radio receiver chip was fabricated in a 0.18 μm complementary metal oxide semiconductor(CMOS) process and packaged in a 48-pin 2 mm×2 mm land grid array chip scale package.The chip consumes 19 mW(LNA1 excluded) and the LNA1 6.3 mW.Measured performances are:noise figure<2 dB, channel gain=108 dB(LNA1 included), image rejection>36 dB, and-108 dBc/Hz @ 1 MHz phase noise offset from the carrier.The carrier noise ratio(C/N) can reach 41 dB at an input power of-130 dBm.The chip operates over a temperature range of-40, 120 °C and ±5% tolerance over the CMOS technology process.展开更多
文摘稀疏多元逻辑回归(SMLR)是高光谱监督分类中的重要方法,然而仅仅利用光谱信息的SMLR忽略了影像本身的空间特征,在少量监督样本下的分类精度和算法的鲁棒性仍明显不足;虽然通过引入核技巧,核稀疏多元逻辑回归(KSMLR)可以部分克服上述缺点,其分类错误仍然有待进一步降低.本文基于核稀疏多元逻辑回归分类误差的统计建模分析,提出一种联合核稀疏多元逻辑回归和正则化错误剔除的高光谱图像分类模型.提出的模型通过引入隐概率场,采取L1范数度量KSMLR分类误差的重尾特性建立数据保真项;利用全变差(Total Variation,TV)正则化度量隐概率场的局部空间光滑性.由Indian Pines和University of Pavia数据集等实测数据应用表明,该方法可以得到更鲁棒和更高的分类精度.
文摘根据一种X波段船舶导航雷达的总体技术指标,研制了一款与之配套的低噪声镜像抑制射频前端接收机。整个接收机由限幅、低噪声放大、镜像抑制混频三个主要功能模块构成。在研制过程中采取由独立到集成的研制思路,在每个独立模块的性能经测试符合技术指标的基础上再进行整个接收机的集成设计及实验测试,给出了接收机的噪声及链路增益测试曲线。测试结果表明:该射频接收机在9.36 GHz^9.46 GHz频率范围内具有3.6 d B的噪声系数及2.5 d B的链路增益,镜像抑制度达到30 d B,各项性能指标均满足船舶导航雷达使用要求。整个前端模块体积小、成本低,适合民用领域的规模化生产。
文摘针对机载设备小型化、轻量化、低功耗等要求,采用射频电路小型一体化技术、大功率发射等方法,设计了一种X波段低噪声系数、多次变频等功能的一体化收发组件。收发组件的主要指标噪声系数≤3 d B;镜像抑制≥50 d B;发射泄漏幅度在-10~0 d Bm;输出脉冲功率≥30 W。组件用于某雷达,已通过试验验证,性能稳定,具有较强实用性。
基金supported by the National Natural Science Foundation of China(Grant Nos.61171194,61120106004)"111"Project of China(Grant No.B14010)
文摘We present a method for detecting oil spills in a complex scene of SAR imagery,including segmenting oil spills,and avoiding false alarms.Segmentation is carried out using a multi-time and multi-hierarchical method by dividing the complex sea surface into bright sea and dark sea.Gray-based and edge-based segmentations are done to extract oil spills from bright and dark sea,respectively.The proposed method can extract complete oil spills,obtain better visual results,and increase detection probability more accurately than the traditional method.Based on the surrounding features and the oil spills’features,dark land spots and low contrast dark spots are removed efficiently,thus reducing false alarms.The experimental results demonstrate that the proposed algorithm has fast computation speed,high detection accuracy,and is very useful and effective for detecting oil spills in SAR imagery.
基金Project supported by the National Natural Science Foundation of China (Nos. 60725415 and 60971066)the National High-Tech R & D Program (863) of China (Nos. 2009AA01Z258 and 2009AA 01Z260)
文摘A 19 mW highly integrated GPS receiver with a ΣΔ fractional-N synthesizer is presented in this paper.Fractional-N frequency synthesizer architecture was adopted in this work, to provide more degrees of freedom in the synthesizer design.A high linearity low noise amplifier(LNA) is integrated into the chip.The radio receiver chip was fabricated in a 0.18 μm complementary metal oxide semiconductor(CMOS) process and packaged in a 48-pin 2 mm×2 mm land grid array chip scale package.The chip consumes 19 mW(LNA1 excluded) and the LNA1 6.3 mW.Measured performances are:noise figure<2 dB, channel gain=108 dB(LNA1 included), image rejection>36 dB, and-108 dBc/Hz @ 1 MHz phase noise offset from the carrier.The carrier noise ratio(C/N) can reach 41 dB at an input power of-130 dBm.The chip operates over a temperature range of-40, 120 °C and ±5% tolerance over the CMOS technology process.
