温度梯度下钛合金热防护结构的导波特性研究

目的 实现可重复使用钛合金热防护结构的导波健康监测。方法 针对钛合金热防护结构,提出热–力–电多物理场耦合导波传播建模仿真分析方法,研究温度梯度下钛合金热防护结构中导波的传播特性,以及在温度梯度和裂纹损伤耦合作用下导波的传播特性。结果 20~500 ℃的温度梯度会导致钛合金结构中导波的群速度降低、幅值衰减降低,裂纹损伤使得钛合金结构中导波的群速度、幅值降低,且损伤越大,影响越明显。裂纹扩展至20 mm时,S0模式群速度降低了1.5%,A0模式群速度降低了2%。结论 此模型可为大范围的温度梯度条件下,钛合金热防护结构上传感器优化布置以及导波监测方法的研究提供指导。     

石化企业电力电缆振荡波局部放电检测技术探讨

针对石化企业电力电缆故障率较高的现状,探索了电缆振荡波局部放电检测及故障定位的原理,通过搭建500 m的10 kV高压电缆实验平台,分别开展典型绝缘缺陷的串联谐振、振荡波对比实验研究,并尝试了振荡波局部放电检测方法在企业现场的应用。通过电力电缆振荡波与串联谐振的对比实验发现,在检测电缆绝缘缺陷时二者具有一定的等效性,可以通过局部放电量的大小和变化趋势来综合判定电缆绝缘缺陷的劣化程度,且振荡波检测技术具有测试时间短、设备便携、可准确定位缺陷位置、不会对电缆造成损伤等技术优势,在石化企业具有良好的应用前景。     

低相对介电常数的圆极化径向缝隙天线的研究

径向缝隙天线是高增益、高效率的平面缝隙阵列天线。天线缝隙阵列按一定的规律排布在径向波导的上表面,径向波导内部填充由慢波材料来抑制天线的栅瓣,其中慢波材料的相对介电常数一般的选择范围是1.5~2.5。本文设计的径向缝隙天线中填充径向波导的慢波材料的相对介电常数为1.06。依据径向缝隙天线的设计原则,适当调整缝隙的排布,所设计天线并未出现栅瓣,并且有较好的方向性。天线的仿真结果与测量结果吻合的较好。     

水不耦合装药对深孔预裂爆破应力波能量的影响

从理论上探讨了在深孔预裂爆破过程中,水不耦合装药对爆轰冲击波的形成和应力波传播规律的影响,利用Matlab编程求解了冲击波初始参数和沿爆破孔径向方向上传播到爆破孔孔壁处的参数;并根据弹性理论提出并求解了正入射情况下爆破孔孔壁表面上的初始冲击压力。在淮南矿业集团丁集矿进行了水不耦合装药深孔预裂爆破实验,并对实验获得的应力波信号进行归一化频谱分析研究。数值计算和现场实验均表明:通过在煤层中进行深孔预裂爆破实验研究发现,当ξ的值为1.5左右时,爆生应力波在10~50Hz内的分能量最强,同时具有最高的信噪比,这与理论计算结果相吻合。因而,在利用煤层爆破强化增透技术时应将不耦合装药系数设计为1.5左右,同时适当加大爆破药柱的用量,以获得最佳的增透效果。     

Complementarity,impatience, and the resilience of natural-resource-dependent economies

We study how society's preferences affect the resilience of economies that depend on more than one type of natural resource. In particular, we analyze whether the degree of complementarity of natural resources in consumer preferences may give rise to multiple steady states and path dependence even when resources are managed optimally. We find that, for a given social discount rate, society tends to be less willing to buffer exogenous shocks if resource good are complements in consumption than if they are substitutes. The stronger the complementarity between the various types of natural resources, the less resilient the economy is, and even more so the higher is the social discount rate.     

SF6气体绝缘设备的放电特性研究

采用间接边界元法,给出了层状半空间中沉积谷地对斜入射平面SV波的三维散射解答,并通过与已有结果的比较,验证了本文解答的正确性。进行数值计算,研究了斜入射角度对散射效应的影响,并以基岩上单一土层为例,讨论了基岩刚度和覆盖土层厚度对沉积谷地附近地表位移的影响。研究表明,三维散射与二维散射之间存在本质差别,不能简单地将斜入射平面SV波分解到沉积谷地横截面的面内方向,然后按平面问题进行计算;基岩与土层刚度比对沉积附近地表位移幅值有着较大的影响,但对位移幅值的空间分布影响不大;土层厚度变化不仅影响地表位移幅值的大小,还会改变地表位移幅值的空间分布。     

The potential for combining indigenous and western knowledge in reducing vulnerability to environmental hazards in small island developing states

The benefits of indigenous knowledge within disaster risk reduction are gradually being acknowledged and identified. However, despite this acknowledgement there continues to be a gap in reaching the right people with the correct strategies for disaster risk reduction.

This paper identifies the need for a specific framework identifying how indigenous and western knowledge may be combined to mitigate against the intrinsic effects of environmental processes and therefore reduce the vulnerability of rural indigenous communities in small island developing states (SIDS) to environmental hazards. This involves a review of the impacts of environmental processes and their intrinsic effects upon rural indigenous communities in SIDS and how indigenous knowledge has contributed to their coping capacity. The paper concludes that the vulnerability of indigenous communities in SIDS to environmental hazards can only be addressed through the utilisation of both indigenous and Western knowledge in a culturally compatible and sustainable manner.     

含盐废水电渗析膜分离处理工艺研究

在水资源日益紧张、含盐废水排放量日益增多的大趋势下,寻求经济有效的含盐废水处理技术已成为重要的研究课题。以厦门某食品企业水产品加工腌泡环节含盐废水为研究对象。含盐废水经氨水沉淀、离子交换树脂软化处理,废水中钙镁离子被有效脱除,出水钙镁质量浓度已经降为10．4mg·L-1,达到软水水质标准。软化后的废水经4‰聚丙烯酰胺（PAM）絮凝并通过活性炭吸附,污染密度指数值（SDI）降低至0．41,完全达到膜分离装置进水水质的要求。预处理液再经电渗析膜进一步浓缩分离后,氯化钠质量浓度可由7351mg·L-1提升到78156mg·L-1,对盐分浓缩了10倍以上,达到废水和盐分的处理回收利用。本处理工艺流程简洁,药耗少、能耗低,比较适合小规模含盐废水的综合处理。     

Real-time numerical simulations and experimental research for the propagation characteristics of shock waves and gas flow during coal and gas outburst

When coal and gas outburst occurs, high-speed gas flow and air shock wave with high kinetic energy could be created. In this paper, the formation process of outburst shock waves and gas flow has been analyzed firstly. Afterwards, the numerical simulation models of the roadways with right-angled intersection have been established, by which real-time simulation of the propagation of outburst gas flow and the process of gas transport has been conducted. Gas pressure, gas velocity and gas concentration can be simulated and shown. From analyzing the simulation results, qualitative and quantitative conclusions that the characteristics and patterns of the propagation and attenuation of outburst shock waves and gas flow can be arrived at. Finally, experimental models have been carried out to investigate the outburst shock waves and gas flow at the roadways with the similar shapes as the simulated ones. The results indicate that when shock wave and gas flow passes the intersection, most of the shock wave and gas flow will flow into the roadway of section opposite the intersection, and a little of it would flow into the roadway below the intersection. And turbulence will appear, shock wave reflects and diffracts at branches with more influence on the roadway below the intersection.     

Numerical simulation and study on the transmission law of flame and pressure wave of pipeline gas explosion

Based on FLUENT simulation software, the laws of transmission of flame and pressure wave in pipeline gas explosion were studied. It turned out that, the maximum pressure value of the explosion point is not the maximum value of the whole explosion process; the maximum pressure value of the pressure wave lowers firstly near the explosion point, then rises to a peak, and then drops gradually; two waves divide the space in the pipeline into three sections during the gas explosion transmission. The result is basically consistent between numerical simulation and experiment, and the conclusion from the simulation provides theoretical basis for research on explosion-proof and suppression devices for underground gas pipeline, as well as for technical regulations of installation.