基于物联传感网络的管道内爆炸风险监控系统设计

天然气在封闭的管道中传输,信息难以获取,采集数据不完整,导致无法准确地对管道内的密封不严、腐蚀穿孔等情况及时感知而造成燃气泄漏发生爆炸;将物联传感网络的思想引入到管道内爆炸风险监控中,在管道中布置压力传感器与气敏传感器对管内数据进行采集与处理;针对燃气爆炸模型在系统的软件设计中,用Zigbee网络协议构造物联传感网络,使用多目标优化搜索技术对爆炸危险点进行搜索;实验结果表明,该系统在不同的环境下可以准确地对管道爆炸进行预警,误差在3%左右。     

A novel range-free localization based on regulated neighborhood distance for wireless ad hoc and sensor networks

Range-free localization methods are suitable for large scale wireless ad hoc and sensor networks due to their less-demanding hardware requirements. Many existing connectivity- or hop-count-based range-free localization methods suffer from the hop-distance ambiguity problem where a node has a same distance estimation to all of its one-hop neighbors. In this paper, we define a new measure, called regulated neighborhood distance (RND), to address this problem by relating the proximity of two neighbors to their neighbor partitions. Furthermore, we propose a new RND-based range-free localization method, and compare our localization algorithm with peer classical algorithms in different network scenarios, which include grid deployment, random uniform deployment, non-uniform deployment and uniform deployment with a coverage hole. Simulation results show that ours can achieve better and reliable localization accuracy in these network scenarios.     

保持几何特征的自适应弹性二次曲线模型

物体形状特征的准确提取往往受到图像获取、目标分割等过程中各种因素的影响,因而需要构造一种鲁棒的形状表现来保有其本质特征。揭示弹性二次曲线(EQW)模型中能量权重因子和样条重叠度因子与形状几何特性间的关系,提出一种自适应保持几何特征的EQW形状表现模型,并将该模型与交互式Live Wire算法相结合,应用至图像分割中,对于各种模态图像中的目标进行分割实验。直观上,本文方法能够在去除噪声同时较好地保持目标形状的显著特征;量化结果方面,交互式分割误差保持在较小稳定范围内,引入EQW模型带来的时间开销亦在可接受范围内。     

基于电流变化的环状直流配电网故障定位方法

针对现有故障测距方法无法同时对单极接地故障和极间故障进行定位,以及利用电容放电阶段进行故障定位时忽略了多端换流站都会对故障点注入电流等问题,提出一种利用故障线路上的全电流分量对多端柔性直流配电网进行故障定位的方法。通过联立与故障点相邻两网孔的电压方程,从算法上解决了过渡电阻对求解故障位置的影响。在simulink中搭建6端环状模型对所提方法进行仿真,结果验证所提方法可以在发生线路故障时能快速识别故障并进行可靠定位,满足直流配电网的故障测距要求。     

Effect of high temperature on the mechanical properties of hierarchical porous cenosphere/geopolymer composite foams

A hierarchical porous cenosphere/geopolymer composite foam (FHCs/KGP) was fabricated by the simultaneous incorporation of O₂ pore from hydrogen peroxide and cenosphere filler addition. Effects of both H₂O₂ content and high-temperature treatment on the microstructure, porosity and strength of porous FHCs/KGP foams were investigated systematically. The obtained FHCs/KGP foams showed typical amorphous structure and desirable porosity from 65 to 82%. The composites could crystallize in situ to FHCs/leucite foams above 1000℃. Compression strength of the FHCs/leucite foams showed a maximum value of 5 ± 0.3 MPa when treated at 1000°C. The improvement of mechanical properties for the composite foams was attributed to crack deflection, fractured microspheres and the good bond between the FHCs and matrix. This study could open opportunities to employ cellular foams as alternatives in structure and filtration applications.     

Microstructure and Crystallization Evolution of Directionally Solidified Al–Cu–Si Alloys With the Assistance of a Static Magnetic Field

Metallurgical and Materials Transactions A - We report on the study of the evolution of microstructure and crystallization during directionally solidified Al–Cu–Si alloys with the...     

The high temperature phase transitions of orthorhombic La0.95MnO3

The high temperature phase transitions of orthorhombic La_0.95MnO₃ from room temperature to 1273 K were studied using high temperature XRD technique in air. Two-phase transitions were found in temperature ranges, 373–473 K and 973–1273 K, respectively. The crystal symmetry increases from orthorhombic to rhombohedral then cubic, while the second transition was not completed in the observation of the present study. The first transition could be due to the depression of Jahn–Teller distortion, while the second one could be caused by the ionic oscillation at high temperature. The lattice thermal expansion coefficients of rhombohedral La_0.95MnO₃ from 473 to 973 K were also calculated using lattice parameters.     

马钢直弧型板坯连铸机的设计

介绍了马钢 2 5 0 mm× 1 40 0 mm直弧型坯连铸机设计指导思想、连铸机主要技术性能指标、工艺流程、设备组成及采取的技术措施 :无氧化浇注 ,连续弯曲矫直 ,二冷区气雾冷却及自动控制 ,在线短定尺二次切割 ,对称式双向出坯 ,防止测量基准移位和台阶式对弧样板等。     

磁场凝固处理对稀土贮氢合金结构和电化学性能的影响

研究了贮氢合金凝固过程中施加直流磁场处理对其组织结构和电化学性能的影响。结果表明：磁场处理没有改变AB5型贮氢合金的CaCu5型六方体结构，但使晶胞常数α0、c0增加，晶胞体积增大；合金的电化学容量变化不大，却明显改善了其高倍率放电（C）性能和循环寿命，合金在5C的放电容量提高了27．8％，S200由0．68上升到0．81；合金中氢的扩散系数增大。