任意形状电大尺寸多层吸波散射体研究

电大尺寸散射体研究,特别是覆盖有多层吸波结构的散射体研究,对提高军事装备隐身性能具有重要意义。利用射线跟踪技术和四端网络理论相结合的方法对任意形状的电大尺寸多层吸波散射体进行了研究。照射散射体的入射平面波由一组离散射线描述,散射体的局部区域看作多层平板结构,类比电大尺寸天线罩的电性能分析方法,从而获得散射体对某一入射平面波的空间后向散射特性,同时预估该散射体在空间的最大后向散射方向和相对散射强度。为提高散射体的隐身性能提供理论基础。     

Design and experimental research of internal leakage detection device of buried pipeline ball valve based on valve cavity pressure detection

Valve is a key control component in the oil and gas long-distance pipelines, and the internal leakage detection of the valve has important research significance and application value. In this paper, a new method for detecting internal leakage of the buried pipeline ball valve based on the pressure change of the valve cavity was proposed. Firstly, a simplified internal leakage model of ball valve was established, and the change law of valve cavity pressure under different openings was obtained by finite element simulation. Secondly, a set of detection device was designed based on the internal leakage principle of buried ball valve and an experimental platform of ball valve internal leakage was built. Then, the pressure signal of the ball valve cavity under different openings and different pressures was collected by the pressure sensor, and the relationship between the power source pressure, the opening and the time required for the valve cavity pressure to reach equilibrium was established. Finally, the internal leakage degree of ball valve was simulated by ball valve opening and the Back Propagation (BP) neural network was selected to invert the ball valve opening. The inversion results showed that the maximum relative error of the liquid and gas experiment were 13.4% and 19.1%, respectively. The inversion results also verified the feasibility of BP neural network in the inversion calculation of the internal leakage degree of the ball valve, which provides guidance for the study of the classification of the internal leakage degree. The experiment and inversion results show that the proposed method can realize the detection of the internal leakage of the buried ball valve, which provides application reference in practice.     

埋地油气管道外腐蚀原因及防腐技术的研究进展

基于埋地油气管道周同土壤环境的复杂性,从长输管道外腐蚀控制因素出发,通过对管道周围环境腐蚀性的榆测及金属管道腐蚀机理分析,结合国内外长输管道外防护技术的发展现状,研究比较目前主要防护材料的防腐蚀性能.提出有效的防腐措施.为埋地管道能够安全高效运行提供了理论依据.     

埋地钢质管道风险评估方法在埋地丙烯管道检验中的应用

考虑到埋地丙烯管道的实际情况,将埋地钢质管道风险评估方法运用到埋地丙烯管道的检验上.风险评估方法分为五个方面:确定风险影响因素,确定失效可能性,确定失效后果,计算区段的风险,提出高风险区段的降险措施.     

基于合于使用原则的压力容器安全评定技术

鉴于压力容器应用的广泛性,对其进行安全评估犹为重要。文章阐述了压力容器合于使用评价的方法,并通过对一台中压空气储罐检验发现的一处埋藏缺陷,基于“合于使用”原则进行常规评定,详细分析了评定过程及其参数的确定方法,结果表明对在用含缺陷压力容器进行合于使用评价具有非常重要的工程意义。     

Layered moving-object segmentation for stereoscopic video using motion and depth information

A novel layered stereoscopic moving-object segmentation method is proposed in this paper by exploiting both motion information and depth information to extract moving objects for each depth layer with high accuracy on their shape boundary. By taking a higher-order statistics on two frame-difference fields across three adjacent frames, the computed motion information are used to conduct change detection and generate one motion mask that consists of all the moving objects from all the depth layers involved at each view. It would be highly desirable, and challenging, to further differentiate them according to their residing depth layer to achieve layered segmentation. For that, multiple depth-layer masks are generated using our proposed disparity estimation method, one for each depth layer. By intersecting the motion mask and one depth-layer mask at any given layer-of-interest, the moving objects associated with the corresponding layer are then extracted. All the above-mentioned processes are repeatedly performed along the video sequence with a sliding window of three frames at a time. For demonstration, only the foreground and the background layers are considered in this paper, while the proposed method is generic and can be straightforwardly extended to more layers, once the corresponding depth-layer masks are made available. Experimental results have shown that the proposed layered moving-object segmentation method is able to segment the foreground and background moving objects separately, with high accuracy on their shape boundary. In addition, the required computational load is considered fairly inexpensive, since our design methodology is to generate masks and perform intersections for extracting the moving objects for each depth layer.     

厂级信息监控系统的B/S化实现

针对当前C/S模式下SIS系统的不足,研究设计出B/S模式下的SIS系统方案,有效解决了传统SIS系统"升级难、兼容难、同步难"的问题。系统采用"浏览器-服务器-实时数据库"架构,综合利用SVG技术、JavaScript控制DOM对象模型、Ajax异步刷新技术和Java异步消息模型进行设计。经测试证明,与传统的SIS系统相比,该方案在实用性、可维护性、实时性等方面具有明显优势。     

基于有限元方法的悬空管道稳定性分析

自然灾害中的土体塌陷严重威胁埋地管道的稳定性。为了研究埋地管道在悬空塌陷区的稳定性,基于有限元方法,研究了壁厚、外径不同的埋地弯管在悬空状态下的位移、应变和应力;采用特征值屈曲理论,研究了一定条件下埋地弯管在土体塌陷时所能承受的极限长度。结果表明,减小管道在土体中的埋深、增大管道外径以及壁厚,可以有效降低管道在土体塌陷过程中的位移,管道的应力和应变均发生在塌陷区的中心和两侧固支端的位置;管道外径、壁厚的提高,可以在一定程度上抑制局部应力过高;埋地弯管在采空区的极限长度约为87 m,并且增大管道外径和壁厚可增强埋地弯管在土体塌陷过程中的抗屈曲能力。     

冀中坳陷孙虎潜山带裂缝发育特征及定量预测

为了明确冀中坳陷孙虎潜山带裂缝发育特征,通过地震、岩心及成像测井等资料归纳裂缝类型,对裂缝参数进行定量表征,分析裂缝主控因素并定量预测裂缝的分布规律。结果表明,研究区碳酸盐岩储层主要发育北东—南西向的高角度构造裂缝,裂缝充填程度较弱有效性高。单井线密度分布在1.0~6.8条/m,裂缝高度主要分布在10~40 cm。构造变形强度大、断层发育程度高的部位裂缝的发育程度越高;白云岩中平均裂缝密度为0.68条/m,裂缝最为发育;埋藏深度越低,裂缝发育强度越大,厘定出风化壳控制优质储层厚度为50~160 m。通过建立分形生长模型预测孙虎潜山带裂缝分布规律,预测结果与测井解释结果一致。     

Distribution of distinguishable objects to bins: generating all distributions

In this paper we give an algorithm to generate all distributions of distinguishable objects to bins without repetition. Our algorithm generates each distribution in constant time. To the best of our knowledge, our algorithm is the first algorithm which generates each solution in O(1) time in the ordinary sense. As a byproduct of our algorithm, we obtain a new algorithm to enumerate all multiset partitions when the number of partitions is fixed and the partitions are numbered. In this case, the algorithm generates each multiset partitions in constant time (in the ordinary sense). Finally, we extend the algorithm to the case when the bins have priorities associated with them. Overall space complexity of the algorithm is O(mklgn), where there are m bins and the objects fall into k different classes. In a companion paper, the generation of all distributions of identical objects to bins is also considered.