基于ERDAS IMAGINE的城市三维景观构建

城市三维景观构建是数字城市建设的一个关键.在阐述数字摄影测量方法构建三维景观优越性的基础上,利用ERDAS IMAGINE遥感图像处理软件的强大功能完成城市区域三维景观的构建,生成虚拟现实世界,为城市三维景观的建设提供了新的方法.     

基于摄影测量校正的斜光轴数字图像相关方法

提出一种针对单相机、斜光轴测量条件下,基于摄影测量校正的二维数字图像相关法(DIC).变形前,在被测物表面粘贴不少于3个控制点(圆形标志点),通过摄影测量技术得到控制点的三维坐标,利用控制点的三维坐标及其在图像上对应的二维坐标,通过空间后方交会法得到斜光轴相机的三维空间方位,拟合控制点的三维坐标得到控制面.变形过程中,...     

架空多导体传输线缆的电磁脉冲响应计算

地面电子设备之间的多根互连平行线缆受高空核爆电磁脉冲(HEM P)作用,会产生瞬态电磁效应。为研究这个问题,该文建立了考虑有耗地面影响等因素的多导体传输线模型,给出了一种类似“状态转移矩阵”表达的方程解的形式,并以相模变换的方法推导了解的具体表达式。该模型可以同时考虑空间电磁脉冲场在线缆上感应的瞬态电压和电流。仿真计算结果表明,对于平行放置的多根线缆而言,接地平行线缆对临近平行线缆有一定程度的屏蔽作用,可供防护设计时参考。     

气体再燃燃烧器喷口流动特性冷态实验研究

以某350 MW锅炉为原型建立冷态模拟试验台,研究气体再燃技术中再燃气体和炉内旋转气流的混合程度及气体再燃条件下实验炉内的空气动力场,并采用标准k-ε湍流模型对其进行了数值模拟.结果表明,不同的再燃风速度对炉内的空气动力场有影响.再燃风速度过小时,再燃风偏离射流轴线较早,不能射入炉膛旋转气流的中心部位;而当再燃风速度过大时,导致再燃风射穿炉内旋转气流.以上两种情况均不能对炉内气流起到很好的覆盖效果,进而影响着再燃气体和炉内气体的混合程度.     

山地城市交叉口车辆纵行运行特性

为研究车辆在山地城市道路交叉口停车减速阶段的运行特性,利用无人机采集了某山地城市道路交叉口的高空视频数据。基于云平台DataFromSky AI,采用Lucas-Kanade和背景差分等算法提取视频中车辆的速度和加速度等数据。按照不同坡度类型,分析停车减速过程中速度变化特征、停车点位置分布规律等运行特性。结果表明：在不同坡度路段,越靠近停止线的车辆其截面初速度越大,离散程度越高;停止线位置处的速度均与停车距离具有较强的正相关性;上坡路段车辆截面初速度、减速率和速度降幅均小于下坡路段;车辆与停止线距离越近,其停车位置点分布越集中;下坡路段车辆停车点位置更分散,分布的区间也较大,停车距离也逐渐增大。本次研究结果可以为山地城市道路交叉口仿真模型参数标定与修正等方面提供理论支撑和数据支持。     

无安定器航弹刚体运动模型研究

无安定器航弹因不具有传统意义上的飞行稳定性,其飞行过程不同于带尾翼的航弹,现有的以稳定飞行为基础的航弹弹道模型已经无法揭示其运动规律。该文以刚体一般运动理论为基础,引入了斜置坐标系和摆动轴坐标系,提出了航弹摆动角速度矢量轴高低角和方位角、斜置姿态角等概念,确定了姿态角与斜置姿态角之间的转换关系,建立了能够准确反映无安定器航弹空中运动特性的刚体运动模型。仿真计算结果表明：利用该模型求解无安定器航弹的弹道问题,克服了使用常规航弹弹道模型出现的“无界”问题,既可以准确地计算无安定器航弹的质心运动轨迹,还可以准确地描述摆动角速度矢量的变化规律,为全面掌握无安定器航弹的弹道特性奠定了基础。     

Task Offloading Strategy Based on Mobile Edge Computing in UAV Network

When an unmanned aerial vehicle (UAV) performs tasks such as power patrol inspection, water quality detection, field scientific observation, etc., due to the limitations of the computing capacity and battery power, it cannot complete the tasks efficiently. Therefore, an effective method is to deploy edge servers near the UAV. The UAV can offload some of the computationally intensive and real-time tasks to edge servers. In this paper, a mobile edge computing offloading strategy based on reinforcement learning is proposed. Firstly, the Stackelberg game model is introduced to model the UAV and edge nodes in the network, and the utility function is used to calculate the maximization of offloading revenue. Secondly, as the problem is a mixed-integer non-linear programming (MINLP) problem, we introduce the multi-agent deep deterministic policy gradient (MADDPG) to solve it. Finally, the effects of the number of UAVs and the summation of computing resources on the total revenue of the UAVs were simulated through simulation experiments. The experimental results show that compared with other algorithms, the algorithm proposed in this paper can more effectively improve the total benefit of UAVs.     

Pharmacokinetics,Prostate Distribution and Metabolic Characteristics of Four Representative Flavones after Oral Administration of the Aerial Part of Glycyrrhiza uralensis in Rats

(1) Background: The aerial part of G. uralensis had pharmacological effects against chronic non-bacterial prostatitis (CNP), and flavonoids are the main efficacy components. The purpose of this study was to obtain the pharmacokinetics, prostate distribution and metabolic characteristics of some flavonoids in rats. (2) Methods: The prototype flavones and the metabolites of four representative flavonoids, namely puerarin, luteolin, kaempferol and pinocembrin in plasma, prostate, urine and feces of rats were analyzed by UPLC-Q-Exactive Orbitrap-MS. In addition, the pharmacokinetic parameters in plasma and distribution of prostate of four components were analyzed by HPLC-MS/MS. (3) Results: In total, 22, 17, 22 and 11 prototype flavones were detected in the prostate, plasma, urine and feces, respectively. The metabolites of puerarin in the prostate are hydrolysis and glucose-conjugated products, the metabolites of kaempferol and luteolin in the prostate are methylation and glucuronidation, and the metabolites of pinocembrin in the prostate are naringenin, oxidation, sulfation, methylation and glucuronidation products. The t_1/2 of puerarin, luteolin, kaempferol and pinocembrin was 6.43 ± 0.20, 31.08 ± 1.17, 18.98 ± 1.46 and 13.18 ± 0.72 h, respectively. The concentrations of the four flavonoids in prostate were ranked as kaempferol > pinocembrin > luteolin > puerarin. (4) Conclusions: Methylation and glucuronidation metabolites were the main metabolites detected in the prostate. A sensitive and validated HPLC–MS/MS method for simultaneous determination of puerarin, luteolin, kaempferol and pinocembrin in rat plasma and prostate was described, and it was successfully applied to the pharmacokinetic and prostate distribution studies.     

Operation of the main steam inlet and outlet interface pipe of a nuclear power station

A method is proposed to measure the process margin of the main steam inlet and outlet pipe of a nuclear power plant by using an industrial photogrammetry system.This method includes steps of preparation, image acquisition, image processing, and result analysis, as well as the final process-ing margin analysis, and so on.In particular, it suggests a specific method for target-point layout and design of shooting network for the main steam inlet and outlet pipe measurement, and then uses a method of sub-section photography and collation to measure the inner and outer surfaces of the nu-clear power interface pipe.The machining tolerance analysis shows that the method can effectively test whether the machining tolerance data of the interface pipe' s top surface, outer surface and the inner surface reach a critical value, which provides a reliable reference for the next step in this process, and it is a type of machining tolerance detection method worthy of popularisation.     

基于改进差分进化算法的无人机在线低空突防航迹规划

为了解决无人机在部分未知敌对环境中的低空突防航迹规划问题,提出了一种改进的差分进化算法.该算法的进化模型采用冯.诺伊曼拓扑结构,并对其进行拓展,使种群在进化初期保持多样性,避免进化早期陷入局部最优,而进化后期加快收敛速度.该算法改进了差分进化算子中的变异操作,从而加快算法的收敛速度,快速找到多目标优化问题的最优解;同时,采用将绝对笛卡儿坐标和相对极坐标相结合的编码方式以提高搜索效率.将该算法用于无人机在线航迹规划仿真实验,并和未改进的算法结果作比较,验证了该算法的有效性.