Microstructure and mechanical property of (TiB2-SiC) agglomerate-toughened B4C-TiB2-SiC composites

B₄C-TiB₂-SiC composites toughened by (TiB₂-SiC) agglomerates were prepared via reactive hot pressing with B₄C and TiSi₂ as raw materials. Phase composition, microstructure, and mechanical properties of the fabricated composites were investigated. The function of (TiB₂-SiC) agglomerates was analyzed, and the strengthening and toughening mechanism were also discussed. Results indicated that some of the in situ formed TiB₂ and SiC were interlocked to form special (TiB₂-SiC) agglomerates in the matrix. The good comprehensive performances of 510 MPa flexural strength, 5.84 MPa·m^1/2 fracture toughness, and 31.93 GPa hardness were obtained in the composites fabricated with 30 wt% TiSi₂. The in situ introduced fine TiB₂ and SiC grains refined the grains of B₄C due to the pinning effect, which enhanced the strength. The special (TiB₂-SiC) agglomerates and the existing toughening phenomena such as crack deflection, branching, and microcrack regions induced by the mismatch of thermal expansion coefficients, had cumulative effects on improving the fracture toughness.     

用于矿山等极端环境中的高精度定位算法

高精度室内定位技术在矿山、建筑、施工等多种极端环境下都有需求。基于超宽带通信(Ultra Wideband,UWB)的室内定位技术能够提供较高的定位精度,但超宽带信号易受到障碍物的干扰,并且在类似矿山等极端环境中,障碍物不可避免。因此,超宽带非视线传输(Non-Line-of-Sight,NLoS)测距成为当前的一个研究热点。当前研究大多集中在识别和消除非视线传输对超宽带测距的影响上,实际应用中,大多数情形下超宽带信号根本无法穿透障碍物,会导致定位标签只能够与2个或1个信标节点通信,但完成三边定位至少需要3个信标节点。为此,提出了一种基于目标行为分析的定位算法,该算法能够在短时间内仅剩余一个信标节点与标签通信时,也可实现高精度定位。该算法以超宽带通信为基础,使用信号飞行时间(Time of Flight,TOF)算法测距并定位。通过分析信号正常时的目标运动轨迹来判断其速度和方向,当信号不正常时(可通信的信标节点减少),可利用预测的速度和方向参数来实现辅助定位。将该算法部署在一个基于超宽带定位的系统中进行了测试,结果表明:当能够与标签通信并完成TOF算法的信标节点数量少于3个时,基于NLoS传输识别和消除的算法无法完成定位,而基于目标行为分析的定位算法依然能够实现定位,在单信标节点区域的平均定位误差为0.93 m,最大误差为1.41 m,在2个信标节点测距的区域,平均定位误差为0.64 m,最大误差为1.2 m。     

基于昂普分析的黄冈大别山世界地质公园旅游开发研究

黄冈大别山世界地质公园拥有4大类12亚类53处地质遗迹资源,为中国自太古代以来的中央造山带形成演化的天然实验室,大别山地区旅游资源丰富。游客量和旅游收入逐年稳步增加,但公园旅游客源地空间的集中程度高,以湖北省武汉市游客为主,外省游客以周边地区居多。游客出游距离以短程为主。旅游业向着多元化和融合创新的全域旅游发展,而地学旅游资源产品单一化对于大众游客缺乏吸引力,以地学旅游为核心的旅游形式和内容需要再进一步开发。通过昂普分析,提出了具体的地学旅游资源开发对策与措施,旅游产业融合产业创新,提高公园旅游一体化服务水平,打造地质与人文一体旅游,发展以世界级地质公园地学旅游为主的多元化旅游活动和旅游产品,打造有效的地学旅游宣传推广体系。公园作为地学和文化综合旅游目的地,应加强区域间旅游合作建设,拓宽公园旅游市场。     

Research on optimization design of PWR flow distribution device based on numerical simulation

ABSTRACT

In the lower chamber of pressurized water reactor (PWR), the flow distribution device is the core module to distribute coolant into the core. It has complex structure and numerous design parameters. Therefore, it has important theoretical and practical significance to optimize the device. The mesh independence verification, turbulence model selection, and data processing all can influence the numerical simulation results of the lower chamber, in order to research the influence, a numerical simulation method based on the original model of CNP1000 reactor lower chamber is proposed in this paper. In the method, an optimization design method of flow distribution device is established based on surrogate model. The main design variables and optimization objectives are determined based on the device’s structure and function characteristics. And then it respectively adopts Kriging algorithm and multi-objective genetic algorithm to establish a surrogate model of flow distribution device and optimize it globally. Finally, the optimal design variables are obtained. Compared with the device’s performance before optimization, the after optimization has smaller total pressure loss and more uniform flow. The effectiveness and practicability of proposed optimization design method can be verified.     

广东省陶瓷行业的能耗现状及节能措施

改革开放20多年来,广东陶瓷行业取得了令人瞩目的成绩,但也存在着能源消耗大、利用率低等问题。本文就广东陶瓷行业的原料制备、制品成形、干燥和烧成过程中的能耗现状进行了综合的分析和评价,并提出了相应的节能措施。     

胶料中炭黑分散度的表征

分别通过PRA2000橡胶加工分析仪和炭黑分散度仪对混炼胶和硫化胶中炭黑分散度进行测定,并对两种方法的测定结果进行对比。结果表明,通过橡胶加工分析仪测得的混炼胶中炭黑分散CBDI值与通过炭黑分散度仪测得的硫化胶中炭黑分散等级有很好的相关性,可根据胶料状态选择适宜的炭黑分散度测试表征方法。     

高位转换耗能减震结构新体系

本文总结了高位转换结构体系的研究与应用情况,分析了高位转换结构体系在实际应用中存在的问题和不足;为解决高位转换结构体系存在的本质问题,提出了将耗能减震技术应用于高位转换结构体系中,形成高位转换耗能减震结构新体系;探讨了该新体系的优越性和在实际工程中应用应解决的问题。     

输电塔十字插板连接节点强度分析

介绍了某大跨越输电塔的节点强度试验概况,着重选取了一典型的平面K型十字插板连接节点进行试验数据分析及有限元计算,检验了设计的准确性和构造的合理性,考察了十字插板连接节点的受力特点,并指出了主管管壁上与节点板连接处存在的较为明显的应力集中现象,以供实际工程设计参考。