Anti-interference method for HF radars by transmitting phase-modulated chirps

Radio frequency interference （RFI） is a major problem in high-frequency （HF） radars. Conventional filtering-involved RFI suppression methods may introduce distortions to the target signals of interest and often demand extra hardware costs. In this paper, a novel method for RFI suppression by using linearly or randomly phase-modulated （PM） chirps is proposed, which enables independent analyses of the target signal and the RFI. Furthermore, the directions of arrival （DOA） of the interference are used as constraints to ensure a better DOA estimation of the target. The effectiveness of the method is demonstrated by numerical simulation results. The method can greatly improve the anti-interference capabilities of HF radars and is extremely applicable in the portable and low-cost radar systems.     

基于A*算法的远程导弹三维航迹规划算法

提出了一种基于A*算法的三维航迹规划方法.该方法将远程导弹的运动学模型离散化,利用导弹过载作为控制量,并结合约束条件,直接对三维空间进行最优航迹搜索.航迹规划过程不仅结合了导弹的本身机动特性,并且充分利用地形信息进行地形回避和威胁回避.仿真实验表明,该方法能够直接规划出三维空间中满足导弹过载约束的最优航迹.     

分数阶傅里叶变换在合成孔径雷达目标识别中的应用

本文通过分析合成孔径雷达动目标回波线性调频特点,采用分数阶Fourier变换对合成孔径雷达动目标进行检测,对其多普勒参数进行比较精确的参数估计,并通过理论分析和模拟计算证明该方法的有效性。     

面向敏捷工艺设计的任务模型及任务分派算法

工艺设计任务分派与进度监控是工艺设计活动组织管理的重要内容 ,应用计算机辅助实现这些功能是提高工艺设计活动总体敏捷性的有效途径。为开发和建立支持工艺设计任务分派与进度监控的敏捷工艺设计系统 (ACAPPS) ,提出了基于网络的分布式并行工艺设计工作模式 ,建立了该工作模式下的工艺设计任务模型 ,针对工艺设计任务的分派给出了一种最大优先分派算法。     

阳离子交换树脂作催化剂合成乙酸乙酯的反应动力学

为研究乙酸和乙醇在阳离子交换树脂 NKC- 9上的反应动力学 ,利用间歇搅拌釜式反应器进行了实验测定。在消除内、外扩散影响的条件下 ,以拟均相模型对实验数据拟合 ,得出了 6 0 ,70 ,80℃下正反应与逆反应的反应速率系数。并在此基础上 ,测定了温度、催化剂浓度对反应速率的影响。反应速率随温度的升高而加快 ,二者关系符合 Arrhenius方程 ,该反应的活化能为 40 .6 4k J/ mol,反应速率与催化剂浓度有关 ,在实验范围内 ,反应速率与催化剂浓度呈线性关系     

基于单一数据源的产品BOM多视图映射技术

为实现产品全生命周期中的物料清单 (bill ofmaterial,BOM)信息集成 ,提出了基于单一数据源的产品BOM数据多视图映射技术 ,初步建立了 BOM多视图映射的基本理论和 BOM主要视图间的 BOM映射类型 ,分析了BOM多视图间的数据映射关系 ,基于基元化组件重构理论 ,设计了 BOM多视图数据映射平台和 BOM视图映射工具组件 ,实现了分布式环境下的 BOM主要视图间的数据映射     

Geochemistry and petrogenesis of Jurassic high Sr/low Y granitoids in eastern China: Constrains on crustal thickness

The Jurassic high Sr/low Y granitoids in eastern China are characterized by high Sr/Y (27—166) and La/Yb (14—66) ratios, low abundance in Y (6—21 μg/g) and Yb (0.5—2.0 μg/g), comparable with those of adakites defined by Defant et al. Thus, they were recently considered as adakitic rocks by some researchers. Compared with the typical adakites in circum-Pacific margins, however, these high Sr/low Y granitoids have higher K₂O (-3.5%) but lower Al₂O₃ (-16.0%) as well as lower Mg^# (-38) and δ Sr_N (-1.23) values. Furthermore, they show relatively flat HREE patterns with Y/Yb values of -10 close to the chondritic value. These geochemical characteristics indicate a residue mineral assemblage of hornblende, garnet and plagioclase for these high Sr/low Y granitoids melt. Thus, they were generated by partial melting at 9—13 kbar (30—45 km in depth), similar to the Archaean high-Al TTG rather than the modern adakites. Generation of these high Sr/low Y granitoids cannot be considered as evidence for a thickened crust (>50 km) and/or the presence of the “Eastern China Plateau” in Jurassic.     

Assessment of blood and oxygen delivery to flaps of rhesus using near infrared steady-state spectroscopy

Near infrared spectroscopy has been considered as a potentially ideal noninvasive technique for the postoperative monitoring of plastic surgery. In this study, 6 flaps were raised on rhesus monkeys' forearms. Blood and oxygen delivery to these flaps was monitored following vascular occlusions and inhalation of pure oxygen. Optical fibers were adopted in the probe of the oximeter so that the cutaneous detection could be performed in reflectance mode. Different and repeatable patterns of changes were measured following vascular occlusions on flaps. It is clear that the near infrared spectroscopy is capable of postoperatively monitoring vascular problems in flaps, especially the venous problem. Near infrared spectroscopy showed high sensitivity to detect the dynamic changes in flaps induced by inhalation of pure oxygen in this study. The experimental results indicated that it was potential to assess tissue viability utilizing the dynamic changes induced by some noninvasive stimulation (such as inhaling pure oxygen). It may be a new assessing method that is rapid, little influenced by other factors and less inconvenient to patients.     

基于神经网络的公路边坡冲刷量模拟计算

神经网络模拟采用三层前馈网络模型，输入层有3个结点，分别代表30min降雨强度、降雨历时和降雨量，表示冲刷外因。输出层只有一个结点，代表坡面冲刷量；隐层结点数采用7个，即土压实度、坡度坡长、径流流速、径流流量、土颗粒粘聚力、植被指数和人为干扰等，为影响冲刷量的主要因素。为了验证模型，在连徐高速公路路堤边坡用SR型人工降雨设施进行冲刷试验，得到冲刷量实测资料，将通过模型计算的冲刷量值与之比较，显示了模型具有较好的模拟预测效果。     

超临界CO2萃取啤酒花及其应用

对啤酒花的超临界CO2萃取物的组分进行了分析，气相色谱图表明了超临界CO2和液态CO2萃取物的异同；并对超临界CO2萃取物进行酿酒试验，结果表明超临界CO2萃取物不仅增加啤酒香味，还能改善口味。