采用遗传算法优化气体探测器布局策略研究

石油石化装置具有结构复杂且危险性高的特点,所加工物料多为易燃易爆有毒物质,且工艺单元之间集成度高,一旦发生泄漏若无法及时探测到则易形成气液积聚和火灾爆炸后果强化,装置拥塞度高使人员逃生困难。火气系统FGS作为安全关键系统,其中的气体探测网络如何快速可靠的实现对气体泄漏事件的探测显得尤为重要。已知探测时间,通过引入遗传算法利用其全局搜索的特点克服传统分支定界法的缺点,实现立体空间不同高度下设置探测网络达到场景全覆盖和缩短探测时间,同时求出探测时间附近的多组最优解,为探测器放置提供多种布置方案。通过与传统等间距探测器布置方案比较,从多种布置方案中选择更符合实际的最佳方案。通过海上浮式生产储油船的生产夹板气体探测案例,验证了所提方法的有效性。     

细河水质监测点的优化布设

水质监测点的布设直接影响着是否完整、客观的反映整个水域水质状况。文章采用动态贴近度法,对阜新市细河进行监测点布设。结果表明:已有水质监测点布设不合理;该模型具有放大作用,聚类效果相对明显,优化点具有代表性,可以真实反映细河水质变化动态,同时减少监测工作量。     

“十二五”地表水国家环境监测网络吉林省水环境国控监测点位布设的构想

根据国家环境质量监测网络,对十二五地表水环境质量监测断面调整工作要求,吉林省在辖区内所有水环境质量监测断面及采样点基础上,完成了松花江流域和辽河流域国控监测断面的优化调整工作。在此过程中,如何从国家尺度上,既能充分反映吉林省水环境质量状况,又能满足国家对地表水环境管理需求进行了深入思考。本文以吉林省为例,在确定国控监测断面及采样点的布设中,提出了自己的构想和建议。     

连续弯曲河道段桥位布置及通航安全分析

基于MMG船舶操纵运动数学模型基本理论,利用龙格-库塔方法进行积分计算求解方程组,将船舶的各受力方程结合流场数学模型计算的表面流场数据在MATLAB软件中编制成船舶操纵运动数值模拟可视化程序,以洞庭湖澧水洪道安乡大桥建设工程为背景,计算分析桥梁建设后航道弯曲半径及桥前直线段距离对通航安全的影响.结果表明,船队通过连续弯曲河道出弯时占用的航宽增大,千吨级航道中的弯曲半径取《内河通航标准》中单弯情况规定的最小值480 m时,上游出弯口与大桥间的安全直线段距离需6倍船长以上.距离为5倍船长时,航道弯曲半径应增大至550 m,无法达到相应的航道弯曲半径时,下游桥孔的通航跨距应相应增加15.8％.     

40°N以北城市夏季气候舒适度及消夏旅游潜力分析

全球气候变暖导致我国夏季普遍高温,传统的近距离山地避暑,已不能满足大众对凉爽气候环境的需求。论文着眼我国高纬地区消夏旅游,选取212座城市1980—2010年长期气候观测数据,利用温湿指数、风寒指数、衣着指数对40°N以北城市夏季气候舒适度进行定量测评。研究结论如下:1从气候舒适度角度分析,空间上,东北地区适合消夏旅游的地域广阔,内蒙古和新疆北部山地,适合消夏旅游地域较小;时间上,6月气候舒适度最舒适,均值为7.62,8月次之,7月较差,均值仅6.81。2从旅游舒适期长短分析,东北三省以及新疆的阿勒泰消夏期最长,达60多天,而河北北部、内蒙古中部、新疆伊犁消夏期为30~45 d,内蒙古西部、新疆天山谷地最短,小于30 d;时间上,一年中8月舒适期最长,均值25.1 d,7月次之,6月最短,均值为19.9 d。3高纬地区,消夏旅游区划分为6种。在我国更适宜消夏旅游的地区,主要分布在我国高纬地区的中东部,并且以东北三省最具竞争力。研究可为游客消夏旅游目的地选择和相关部门消夏旅游开发及战略制定提供参考。     

Safety-based process plant layout using genetic algorithm

This paper presents a method based on a genetic algorithm for optimizing process plant layout. The relative location of main process units is determined to minimize an annual cost function including the cost of material transfer between process units (piping and pumping costs), land cost, and the expected annual loss resulting from damage to each secondary unit caused by primary accidents occurring in nearby process units. This method is an improvement over previous attempts using genetic algorithms or mathematical programming techniques to optimize plant layout, which neglected pumping costs and included safety issues by evaluating the infringement of predefined safety distances only. In this approach the operating cost of material transfer is included and the likelihood of accidents is taken into account thus providing good practical solutions to the plant layout problem incorporating more realistic cost functions and constraints. In the paper, after discussing the structure of the annual cost function and describing the working logic of the layout generating algorithm, a case study is described to demonstrate the effectiveness of the proposed methodology.     

基于地质灾害危险性评价的建设用地布局规划

":5.12"汶川地震诱发了都江堰市许多新的地质灾害,恢复重建工作不断遭遇一系列复杂的地质环境问题。文章根据重灾区都江堰市震后地质地理环境特征,优选出坡度、震后地质灾害密度、工程岩组、线性构造密度、土地利用现状、河网密度等6个评价指标,建立分级标准;利用GIS技术对空间数据的采集和分析功能,结合数理统计的方法原理,对都江堰市进行地震诱发地质灾害危险性定量评价。经过精度验证,结果显示震后都江堰市地质灾害高危险区和较高危险区占土地总面积的15.8%,主要位于"5.12"特大地震发震的龙门山推覆构造带的前山推覆构造带上;地质灾害中等危险区分布较广,占总面积的15.8%;地质灾害低危险区和较低危险区分布最广,占总面积的68.4%,主要分布在坡度平缓、植被发育、坚硬或半坚硬的岩组地区,将评价结果与新一轮土地利用总体规划的城镇用地布局、农村集中居住区点位叠加,科学准确地揭示出研究区震后建设用地区域地质灾害空间分布规律,从空间上对建设用地的安全布局进行了预警,为新一轮土地利用总体规划建设用地布局规划方案提供科学的参考。     

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.