瑶湖湖泊水质监测点的优化布设研究

文章采用2010年全年瑶湖水质监测指标的月分析数据,利用物元分析法和动态贴近度法对瑶湖监测点的布设进行了优化分析。研究结果表明,2种方法对瑶湖监测点布设优化后,将原有的14个监测点减至9个监测点,且2种方法优化后所得到的结果基本相同,这为提高监测工作的效率提供了理论上的依据,具有较重要的实践意义。     

Effects of vent layout and vent area on dynamic characteristics of premixed methane-air explosion in a tube with two side-vented ducts

To further elucidate the influence mechanism of side vents on the dynamic characteristics of gas explosions in tubes is helpful to design more reasonable vent layouts. In this paper, 9.5% methane-air explosion experiments were conducted in a tube with two side-vented ducts, and the effects of vent layouts and vent areas on the dynamic characteristics of explosion overpressure and flame propagation speed were investigated. The results demonstrate that under the same condition with a single vent area of 100 mm × 100 mm, when only the end vent is open, the maximum explosion overpressure and the maximum flame propagation speed are the highest among the five vent layouts. When the side vents 1 and 2 and the end vent are open, the maximum explosion overpressure is the lowest, and an unusual discovery is that the flame front changes into a hemispherical shape, finger shape, quasi-plane shape, tulip shape and wrinkled structure. When only side vent 1 is open, a unique Helmholtz oscillation occurs, and a new discovery is that there is a consistent oscillation relationship among the overpressure, flame propagation speed and flame structure. Helmholtz oscillation occurs only when a single vent area is 100 mm × 100 mm–60 mm × 60 mm, and the oscillation degree decreases with decreasing vent area. During the vent failure stage, the maximum explosion overpressure is generated, the flame front begins to appear irregular shape, and the flame propagation speed shows a prominent characteristic peak. After the vent failure stage, the driving effect of the end vent on the flame is higher than that of the side vent on the flame. Furthermore, the correlation equations of the mathematical relationships among the maximum explosion overpressure P_red, the static activation pressure P_stat and the vent coefficient K_v under four vent layouts are established, respectively.     

A new multiple-risk map approach to solve process plant layout considering safety and economic aspects

Mathematical models used to optimize the process plant layout (PPL) with risk reduction have four primary objectives, which are related to the minimization of land, pumping (pipe system), protection system devices, and risk costs. Moreover, these models are of two types: continuous plane models (CPM) and grid-based models (GBM); however, the nonconvexity of the CPM models makes difficult to achieve the global optimum, because it is formulated as Mixed-Integer Nonlinear Programming (MINLP). Thus, the risk map approach has been implemented with the grid-based models to solve problems of process plant layout focused on finding the best possible solution. However, these risk map formulations present important limitations, mainly related with the use of protection devices and the occupied area. Therefore, a new GBM-MILP formulation is proposed to optimize the selection of protection devices and minimize the occupied area. The risk is reduced through the investment on safety devices instead of considering the increase of separation distances. The proposed model was used to solve the layout problem of an ethylene oxide process, and the results was compared with a process layout reported in the literature. The results show that the model can provide the best possible solution; however, the time spent in the calculation is considerably greater than that reported for continuous plane models. Finally, the model can be used by decision-makers to evaluate different layout options for several explosion scenarios, during the early stages of the plant design.     

基于微地貌约束的山区型特色小镇“三生”空间布局优化

优化国土空间开发格局是生态文明建设的重要内容,在村镇尺度下生态-生产-生活(简称“‘三生’”)空间结构与布局,对于特色小镇绿色发展具有重要意义.为优化山区以工业和旅游融合为优势的特色小镇“三生”空间布局,以茅台镇为研究对象,基于“产业兴旺、生态宜居”乡村振兴战略要求,通过10 m分辨率DEM、土地利用等数据,以主导生态功能和山区微地貌为约束条件,通过GeoSOS-FLUS模型开展了生态优先情景下茅台镇“三生”空间布局优化研究,并与无地貌约束的自然演变和经济优先2种情景做了对比.结果表明:①茅台镇生态空间和农业生产空间在峡谷底、陡坡和山脊区域均有大量分布且面积数量差异较小,而生活空间和工业生产空间多分布在峡谷底部.②自然演变情景模拟下,河谷地带的缓坡和部分陡坡位置均被转换为建设用地;经济优先情景模拟下,缓坡位置的耕地较易转化为建设用地;而生态优先情景模拟下,林地实现了空间上的连通和聚集,建设用地主要在茅台镇中南部河谷地带以及缓坡地区适度扩张.③生态优先情景下,峡谷底区域“三生”空间布局得到优化,生态空间面积从41.29 km2增至43.80 km2,工业生产空间面积由6.86 km2增至7.89 km2,农业生产空间由24.29 km2降至20.00 km2.研究显示,对于山区型村镇,微地貌约束土地利用模拟使得工业生产空间和生活空间集中分布在峡谷底区域,而生态空间则较多分布在缓坡和陡坡区域.      

外加电流阴极保护中深井阳极的布置

针对某输油管道工程,为保障阴极保护效果的同时,减少阴极保护对周边金属构筑物产生直流杂散电流的干扰。结合现有相关标准规范以及阴极保护干扰的产生机理,对深井阳极的布置位置和阴极保护方案进行对比分析。由于该工程输油管道将分输库整体包围,如库外长输管道全部采取外加电流的阴极保护形式,无论阳极井如何布置,阴极保护电流均有可能对分输库内储罐等金属构筑物产生杂散电流干扰,此时阳极井的位置需从施工、维护、保护电流的发散以及投资等方面比选确定。为了实现外输管道得到有效保护,且最大程度减小阴极保护电流对分输库内储罐等金属构筑物的干扰,可采取对由分支点进出库区的成品油管道与干线绝缘,并对该部分管道施加牺牲阳极保护的形式。     

工业项目地下水污染监测井布设方案的定量化研究

工业成品生产过程中各类装置所产生的污染源严重威胁着工业建设项目厂区及其周边地下水环境安全,对工业项目厂区及其周边地下水水质进行有效的监测则成为防控地下水污染风险的关键。以某石化项目为例,基于对研究区水文地质条件的剖析和概化,通过野外水文地质调查及现场试验获取水文地质参数,利用FEFLOW数值模拟软件建立研究区地下水三维非稳定渗流模型和溶质运移模型,分析预测设定工况下污染物随地下水的迁移规律,实现了地下水污染监测井布设方案在时间和空间尺度上的定量化分析,并提出了合理且有效的监控管理措施,可为工业项目地下水监测井的精细化布设提供参考。     

天津滨海新区环境状况分析及对策建议

天津市滨海新区包括塘沽、汉沽、大港、开发区、保税区、是近年天津最大的经济增长点,是全市经济发展的新龙头。本文依据近年环境的监测结果,分析了滨海新区的环境现状和主要环境问题,在此基础上提出了实现了新区社会、经济发展与环境,资源保护相协调,走可持续发展之路的对策建议。     

centrifugal用热控装置设计

目的 评估飞行器产品在飞行过程对热–离心综合环境的适应性,研制一套热–离心综合环境试验用热控装置。方法 从热–离心试验需求出发,完成综合试验系统总体研制目标及系统方案设计。针对高g值离心环境（离心加速度值≥90g）下的热载荷加载需求,开展基于热传导的热载荷加载方法研究,并完成适用于高g值环境的热控装置硬件布局优化设计。提出基于分段包络思想的产品响应温度梯度分布效应模拟方法及实现,减少过试验考核。结果 利用该热控装置完成了热–离心综合环境功能验证试验,设置最大加速度为92g,保载时间为3 min,最高加热温度为150℃,最大温升速率为3℃/min,3温区控制,升温过程中,温度误差优于±1.5℃。结论 该热–离心综合环境试验用热控装置可用于飞行器产品热–离心综合环境试验的考核。     

基于社会力模型的三维阶梯教室行人疏散仿真研究

为研究三维阶梯教室内座位布局及单双门对行人疏散效果的影响，改进社会力模型，模拟单双门情况下4种常见座位布局的行人疏散过程，从宏观和微观2个层面分析行人的疏散效果及内在的物理机制。结果表明:在限定门口宽度下，单开后门的平均总疏散时间均小于单开前门，而双门情形下的平均总疏散时间最小；从微观密度图来看，无论是单开前门、单开后门，还是双门均打开，4种座位布局中发生人员拥挤的位置相似。但单开后门情况下高密度区域的峰值高于单开前门，而双门情况下行人承受拥挤的压力最小，发生事故的风险小。     

基于高分遥感的危险化学品重大危险源安全布局动态管控研究*

为遏制危险化学品重特大安全事故，解决传统安全监测手段的空间局限性问题，结合高分遥感与数值模拟技术，开展危险化学品重大危险源区域安全布局动态管控研究。利用数值模拟技术模拟并确定危险化学品重大危险源重点管控范围；基于高分遥感影像提出适用于危险化学品重大危险源安全布局动态管控的变化检测方法，动态监测安全防护范围内的建筑、道路等人工构筑物的变化情况，严控事故影响范围内的人工构筑物密度；以内江市隆桥化工为实例开展示范应用。结果表明:高分遥感技术能够高效监测危险化学品重大危险源安全防护范围内的工程建设情况，有助于危险化学品企业保持足够的外部安全防护距离，降低危险化学品重特大安全事故风险。