基于交流电磁场裂纹缺陷识别仿真研究

为了研究基于交流电磁场裂纹缺陷识别问题，调研了交流电磁场检测的国内外现状，结合交流电磁场技术，利用有限元分析软件ANSYS Maxwell构建常见的裂纹缺陷模型，进行仿真分析。研究了缺陷尺寸的识别以及不同缺陷簇群对交流电磁场(Alternating Current Field Measurement，ACFM）检测信号特征的影响，对提取的Bx和Bz（沿坐标轴X方向和Z方向的磁感应强度）特征信号的影响进行了分析与探讨，得到影响ACFM技术的核心参数，并建立了缺陷深度和长度的测量评估方法。研究结果表明:通过测量Bz曲线的峰谷间距可初步确定缺陷长度； Bx曲线检测同时受缺陷深度和缺陷长度的影响，对于缺陷深度检测灵敏度较低；ACFM技术虽能够实现对缺陷个数的识别，但难以准确识别缺陷尺寸的大小，当缺陷间的距离足够大时，才能准确实现缺陷的定量识别。     

储罐底板维修决策方法研究

储罐底板腐蚀是储罐失效的主要原因之一,对底板的腐蚀检测方法目前有很多种。每种方法都有自己的优势,但同时也存在着相应的弊端。通过在实践应用中对比漏磁检测与超声测厚检测方法,分别指出两种检测方法的优势与实践应用中存在的问题,提出应综合应用两种方法来提高效率和确保准确性。为更好地利用检测技术保障储罐安全提出参考建议。     

VOCs快速检测在某化工企业搬迁遗留污染场地调查中的应用

以天津市某化工企业搬迁遗留污染场地为例,采用VOCs快速检测法辅助现场钻孔取样,以初步判断土壤污染深度,同时将现场样品送实验室检测。试验表明,VOCs快速检测法与实验室检测法结果基本一致。将452个样品测定结果做比对,结果表明实验室检测数据VOCs加和值与快速检测法现场检测数据存在显著相关,R2为0.803 7。污染物主要集中于场地5 m~9 m的粉土层中。其中,13种VOCs检出,4种VOCs超过《场地土壤环境风险评价筛选值》(DB11/T 811—2011)商业用地筛选值。     

Method for identifying errors in chemical process development and design base on accidents knowledge

It has been claimed that the high accident rate in the chemical process industry is due to poor dissemination of accident knowledge that affects directly the level of learning from accidents. In response to this situation, this paper utilized past accident knowledge as a basis to develop a safety oriented design tool whereby the accident information were directly disseminated into plant design. The method was developed based on our previous accident analysis of design error in which the common design errors were ranked in accordance to their frequency and its origins during normal plant design project. Based on the design error ranking and its origin at a specific design phases, a method for design error detection is proposed. The method is expected to be able to identify the possible design error and its causes throughout chemical process development and design. The main objective is to trigger safe design thinking at the specific design phases so that appropriate action for risk reduction could be timely implemented. The Bhopal and BP Texas tragedies are used as case studies to test and verify the method. The proposed method can detect up to 74% of design errors.     

用稳健统计法处理方法标准验证实验中方法检出限数据

方法检出限是分析方法基本性能参数之一。根据《环境监测分析方法标准制修订技术导则》(HJ 168—2010)的要求,此参数需要6家以上实验室基于特定样品测试数据的标准偏差得到。目前,标准文本大多采用各家实验室方法检出限中最大值。研究提出用稳健统计法处理方法验证数据,无需识别和删去离群值,可将离群值的影响降到最小。基于4组公开发表数据和2组实测数据,比较了不同方法计算结果。结果表明:参与统计的3组数据29个检测项目中,常规方法确认的方法检出限被判为离群值占27.6%。取最大值存在数值偏高的风险。提出了用曼德尔k检验法识别1组方法检出限数据中的离群值,该方法同样可以用于实验室数据与标准文本中方法检出限符合性判断。     

某矿热炉烟气余热利用系统测量与诊断

对某铁合金厂2台硅铁矿热炉烟气参数进行了现场测量,测量结果表明,测点烟气温度偏低,流量偏大.通过对原始测量数据进行筛选整理,得到了更加真实的测量结果;通过分析测量数据,诊断出导致现有余热锅炉进口烟气温度偏低的主要原因,并给出相应的对策建议.     

还原一偶氮光度法测定水中硝基苯类的改进

在现行分析水中硝基苯类污染物标准分析方法的基础上，将参加显色反应的水样体积和比色皿厚度各增加一倍，方法检出限由0．20mg／L降低至0．05mg／L。用改进法分析很低浓度的硝基苯类水样，具有很好的现实意义。     

Mechanistic understanding of human–wildlife conflict through a novel application of dynamic occupancy models

Crop and livestock depredation by wildlife is a primary driver of human–wildlife conflict, a problem that threatens the coexistence of people and wildlife globally. Understanding mechanisms that underlie depredation patterns holds the key to mitigating conflicts across time and space. However, most studies do not consider imperfect detection and reporting of conflicts, which may lead to incorrect inference regarding its spatiotemporal drivers. We applied dynamic occupancy models to elephant crop depredation data from India between 2005 and 2011 to estimate crop depredation occurrence and model its underlying dynamics as a function of spatiotemporal covariates while accounting for imperfect detection of conflicts. The probability of detecting conflicts was consistently <1.0 and was negatively influenced by distance to roads and elevation gradient, averaging 0.08–0.56 across primary periods (distinct agricultural seasons within each year). The probability of crop depredation occurrence ranged from 0.29 (SE 0.09) to 0.96 (SE 0.04). The probability that sites raided by elephants in primary period t would not be raided in primary period t + 1 varied with elevation gradient in different seasons and was influenced negatively by mean rainfall and village density and positively by distance to forests. Negative effects of rainfall variation and distance to forests best explained variation in the probability that sites not raided by elephants in primary period t would be raided in primary period t + 1. With our novel application of occupancy models, we teased apart the spatiotemporal drivers of conflicts from factors that influence how they are observed, thereby allowing more reliable inference on mechanisms underlying observed conflict patterns. We found that factors associated with increased crop accessibility and availability (e.g., distance to forests and rainfall patterns) were key drivers of elephant crop depredation dynamics. Such an understanding is essential for rigorous prediction of future conflicts, a critical requirement for effective conflict management in the context of increasing human–wildlife interactions.     

Use of opportunistic sightings and expert knowledge to predict and compare Whooping Crane stopover habitat

Predicting a species’ distribution can be helpful for evaluating management actions such as critical habitat designations under the U.S. Endangered Species Act or habitat acquisition and rehabilitation. Whooping Cranes (Grus americana) are one of the rarest birds in the world, and conservation and management of habitat is required to ensure their survival. We developed a species distribution model (SDM) that could be used to inform habitat management actions for Whooping Cranes within the state of Nebraska (U.S.A.). We collated 407 opportunistic Whooping Crane group records reported from 1988 to 2012. Most records of Whooping Cranes were contributed by the public; therefore, developing an SDM that accounted for sampling bias was essential because observations at some migration stopover locations may be under represented. An auxiliary data set, required to explore the influence of sampling bias, was derived with expert elicitation. Using our SDM, we compared an intensively managed area in the Central Platte River Valley with the Niobrara National Scenic River in northern Nebraska. Our results suggest, during the peak of migration, Whooping Crane abundance was 262.2 (90% CI 40.2?3144.2) times higher per unit area in the Central Platte River Valley relative to the Niobrara National Scenic River. Although we compared only 2 areas, our model could be used to evaluate any region within the state of Nebraska. Furthermore, our expert‐informed modeling approach could be applied to opportunistic presence‐only data when sampling bias is a concern and expert knowledge is available.     

Spatially Explicit Power Analyses for Occupancy‐Based Monitoring of Wolverine in the U.S. Rocky Mountains

Conservation scientists and resource managers often have to design monitoring programs for species that are rare or patchily distributed across large landscapes. Such programs are frequently expensive and seldom can be conducted by one entity. It is essential that a prospective power analysis be undertaken to ensure stated monitoring goals are feasible. We developed a spatially based simulation program that accounts for natural history, habitat use, and sampling scheme to investigate the power of monitoring protocols to detect trends in population abundance over time with occupancy‐based methods. We analyzed monitoring schemes with different sampling efforts for wolverine (Gulo gulo) populations in 2 areas of the U.S. Rocky Mountains. The relation between occupancy and abundance was nonlinear and depended on landscape, population size, and movement parameters. With current estimates for population size and detection probability in the northern U.S. Rockies, most sampling schemes were only able to detect large declines in abundance in the simulations (i.e., 50% decline over 10 years). For small populations reestablishing in the Southern Rockies, occupancy‐based methods had enough power to detect population trends only when populations were increasing dramatically (e.g., doubling or tripling in 10 years), regardless of sampling effort. In general, increasing the number of cells sampled or the per‐visit detection probability had a much greater effect on power than the number of visits conducted during a survey. Although our results are specific to wolverines, this approach could easily be adapted to other territorial species. Poder de Análisis Espacialmente Explícito para el Monitoreo Basado en Ocupación del Glotón (Gulo gulo) en las Montañas Rocallosas de Estados Unidos