A novel target detection approach based on adaptive radar waveform design

To resolve problems of complicated clutter, fast-varying scenes, and low signal-clutterratio (SCR) in application of target detection on sea for space-based radar (SBR), a target detection approach based on adaptive waveform design is proposed in this paper. Firstly, complicated sea clutter is modeled as compound Gaussian process, and a target is modeled as some scatterers with Gaussian reflectivity. Secondly, every dwell duration of radar is divided into several sub-dwells. Regular linear frequency modulated pulses are transmitted at Sub-dwell 1, and the received signal at this sub-dwell is used to estimate clutter covariance matrices and pre-detection. Estimated matrices are updated at every following sub-dwell by multiple particle filtering to cope with fast-varying clutter scenes of SBR. Furthermore, waveform of every following sub-dwell is designed adaptively according to mean square optimization technique. Finally, principal component analysis and generalized likelihood ratio test is used for mitigation of colored interference and property of constant false alarm rate, respectively. Simulation results show that, considering configuration of SBR and condition of complicated clutter, 9 dB is reduced for SCR which reliable detection requires by this target detection approach. Therefore, the work in this paper can markedly improve radar detection performance for weak targets.     

渐开螺旋面啮合误差的广义圆柱坐标测量原理

论述了渐开螺旋面啮合误差测量的新方法——广义圆柱坐标法,给出了测量原理与实现方法、数学模型和数据处理算式;同时,指出了迄今一些文献中论述啮合误差测量时存在的错误。     

飞行器结构力学中的一个问题

最小余能原理的丰富内涵在飞行器结构力学中得到一定反映。研究了飞行器结构力学中余虚功原理的两种不同的表示形式，最小余能原理和拟余能原理，推导了最小余能原理驻值条件。最后，给出典型实例。     

基于经营过程再造的大中型企业MIS设计

论述基于经营过程再造的大中型企业ＭＩＳ设计思想，介绍该系统的结构和功能，给出了在具体实现过程中的关键技术、技术途径和重点难点，提出企业进行管理信息系统设计的新的出发点。     

汽车车身曲面激光自动测量技术研究

针对追求整体协调要求的车身曲面宏观形状测量问题，开发了相应的以激光技术，传感技术、伺服控制技术以及工程应用光学等为基础的自动测量，文章对自动测量的原理、测头随动准则，测头扫描规则以及测点坐标数据采集、传输和处理等内容，均作了较为详细的探讨。     

VLSI芯片测试中用户辅助硬件误差的消除方法

在 VL SI测试中 ,由于用户引入辅助硬件产生的误差问题 ,一直是阻碍测试精度和可靠性的关键问题。本文以 ITS90 0 0 MX为背景 ,介绍在 VL SI测试中 ,对辅助硬件所造成误差的一种解除方法。在现有条件下 ,实现简单、方便 ,可供有相应测试系统的测试工作者参考。     

Improved imaging for X-ray inspection systems

A number of advancements for X-ray inspection systems have recently been implemented in the image presented to the operator. Advances in the use of color and image fusion techniques have been developed to maximize the information available in the initial view shown on the monitor. Different techniques are appropriate depending upon the size of the inspection item. Inspection of checked and carry-on baggage requires imaging methods that would not be appropriate for use on larger, more complex objects such as cargo containers or whole trucks. Color-coded presentation of CT images of baggage imposes yet other demands. Comparative images and analyses are presented to support choices for imaging on L-3 Communications systems in terms of the conflicting requirements of cost, sensitivity, resolution, and penetration. A number of enhancements are available to the operator and their influence on system performance is explored. Some experimental enhancements are demonstrated and their trade-offs discussed. The imaging system is ultimately based on hardware, and the choice of detectors, amplifiers, and sampling methods plays an important role in overall performance. Image degradation can be caused by deficiencies in the imaging hardware. Effects such as detector cross-talk and afterglow will negatively impact system performance. Recognition of these factors and steps to mitigate them are discussed. The effect of X-ray source choices such as beam voltage, milliamps, and sampling rate has a direct influence on the image quality and bag dose. Results of theoretical modeling as well as results on actual systems are presented. For a given bag dose, the trade-off between sensitivity, resolution, and penetration are considered. Possibilities for future advancements in imaging for X-ray inspection systems are explored.     

信号失真度数字化测试算法研究

目前失真测试所采用的传统测试方法已不能适应数字技术发展的要求.本文介绍了基于LabVIEW平台和PXI总线所研究的失真度数字化测试算法,给出了失真度数字化测试的的一种解决方案.     

隐身等离子体的几个相关问题研究

在目标的雷达隐身方面,等离子体具有巨大的应用潜力。对隐身应用时产生等离子体的气压、放电气体种类以及放电方式进行了论述。指出在大气压下,适宜利用惰性气体放电来产生等离子体。而目前许多文献中所报道的隐身等离子体的产生方法离工程应用还有一定距离,还有许多问题亟待解决。