Satellite SAR Remote Sensing of Great Lakes Ice Cover,Part 2. Ice Classification and Mapping

During the 1997 winter season, shipborne polarimetric backscatter measurements of Great Lakes (freshwater) ice types using the Jet Propulsion Laboratory C-band scatterometer, together with surface-based ice physical characterization measurements and environmental parameters, were acquired concurrently with Earth Resource Satellite 2 (ERS-2) and RADARSAT Synthetic Aperture Radar (SAR) data. This polarimetric data set, composed of over 20 variations of different ice types measured at incident angles from 0° to 60° for all polarizations, was processed to radar cross-section to establish a library of signatures (look-up table) for different ice types. The library is used in the computer classification of calibrated satellite SAR data. Computer analysis of ERS-2 and RADARSAT ScanSAR images of Great Lakes ice cover using a supervised classification technique indicates that different ice types in the ice cover can be identified and mapped, and that wind speed and direction can have an influence on the classification of water as ice based on single frequency, single polarization data. Once satellite SAR data are classified into ice types, the ice map provides important and necessary input for environmental protection and management, ice control and ice breaking operations, and ice forecasting and modeling efforts.     

Synfuel development impacts— econometric modelling and policy analysis

The prospects for rapid near-term development of a synfuel industry in the USA have decreased, due to depressed world oil prices, synfuel project cost overruns, and the lukewarm support of the Reagan administration. Nonetheless, socioeconomic and environmental impact analysis studies can provide valuable information for determining the regional welfare effects of proposed projects. The author discusses the results of a regional econometric analysis of the synfuel projects planned for Western Kentucky, which focuses on environmental impacts, and reveals the inevitable trade-offs that would accompany synfuel development. Some policy issues are briefly reviewed, especially that of efficient energy pricing.     

合成孔径雷达图象结构特征检测的改进算法

本义研究合成孔径雷达（ＳＡＲ）图象结构特征检测。首先讨论了 ＳＡＲ图象结构检测的原理,然后在分析Ｌｏｐｅｓ等人的算法的基础上,提出了一个改进的结构检测算法,给出改进算法的实现流程,并利用模拟和实测ＳＡＲ图象进行试验比较,充分验证了改进方法的优越性和实用性。     

基于FPGA的多路声呐信号采集卡的设计

介绍了声呐技术及其应用,并根据声呐特性选择设计使用的功能芯片.较为详细地阐述了用FPGA实现多路声呐信号的模数转换和SRAM乒乓存储.最后给出FPGA各功能模块仿真图.     

变电站综合自动化系统的结构方式

变电站综合自动化系统是电网改造中的重要设备。而系统的结构方式是制约设备性能、造价和可靠性的关键因素。本文结合作者多年来从事电力自动化方面的研究和实践,从分析系统结构方式入手,说明了不同结构方式对设备的性能、造价和可靠性所产生的截然不同的效果。     

Constant Impedance TEM Horn Antenna: Aperture and Characteristic Impedance’s Impacts on Axial Electric Field

TEM horn antenna with constant characteristic impedance (CCI TEM horn antenna) is a widely used ultra-wideband (UWB) antenna. Considering the peak-to-peak value of the axial electric field (V_pp), how to design such antenna’s characteristic impedance (Z _c) has not been involved in previous research. The relationship between V_pp and antenna aperture as well as characteristic impedance is numerical analyzed. The simulation and experimental results show that the optimal aperture is existed to maximize V_pp when the antenna’s length is fixed at the axis. More over, V_pp of the antenna with optimal aperture reaches the maximum value when the characteristic impedance is 280 ohm.     

Key technology of D-InSAR at X-band for monitoring land subsidence in mining area and its application

In theory, land subsidence measurement results with high accuracy can be obtained by using the Differential Interferometry Synthetic Aperture Radar （D-InSAR） at X-band. In practice, however, the measuring accuracy of D-InSAR at X-band has been seriously affected by some factors, e.g., decorrelation and high deformation gradient. In this work, the monitoring capability of D-InSAR for coal-mining subsidence is evaluated by using SAR data acquired by TerrraSAR-X system. The SAR image registration method for low coherence image pairs, the denoising phase filter for high noise level interferogram and atmospheric effects mitigation method are the key technical aspects which directly influence the measurement results of D-InSAR at X-band. Thus, a robust image registration method, an improved phase filter method and an atmospheric effects mitigation method are proposed in this paper. The proposed image registration method successfully achieves InSAR coregistration, while the amplitude cross-correlation cannot properly coregister low coherence SAR image pairs. Moreover, the time complexity of the proposed image registration method is obviously slighter than that of the Singular Value Decomposition （SVD） method. The comparing experiment results and the unwrapping phase results show that the improved Goldstein filter is more effective than the original Goldstein filter in noise elimination. The atmospheric influence correction experiment results show that the land subsidence areas with atmospheric influence correction are more clarified than that of without at- mospheric influence correction. In summary, the presented methods directly improved the measurement results of D-InSAR at X-band.