机载产品日历寿命定寿方法研究进展及展望

联系我国飞机飞行现状,分析了机载产品日历寿命控制的必要性.根据文献记载,简要介绍了航空机载产品日历寿命定寿方法的发展历程,分析了目前机载产品日历寿命定寿方法研究的现状,归纳了3类主要的机载产品日历寿命传统定寿方法,并讨论了各类方法的优点与不足.针对传统定寿方法存在的问题,整理了近年来发展的机载产品日历寿命定寿方法的代表性成果,介绍了3种近年来才发展的机载产品日历寿命定延寿方法的具体过程.客观地综述了我国机载产品日历寿命研究存在的短板与弱项,以及日历寿命研究亟需发展的方向.为使机载产品日历寿命定寿方法研究跟上时代发展的步伐,更经济高效地服务在役飞机寿命控制,对未来机载产品日历寿命研究提出了展望.     

大气监测仪器维护检修能力的评价

一直以来,环境大气监测的数据精度与维护成本,始终是数据应用部门和数据提供部门的难题之一.作者谷学先生根据多年的实档践,首次提出,运用数据对大气监测仪器维护管理进行评价的可行性,并试图建立仪器维护管理作业量化的评价系统.在仪器维护管理中,任何时候,都很难完全排除技术水平比较低的仪器维护检修人员,为了回避这种实际情况,作者通过对数字的分析指出,急需构建环境大气监测仪器维护管理业务能力的评价系统,并期待地方自制体通过评价手段,来选择和指导监测仪器维护管理人员.从而提高数据的精度和减低运转经费的开支.     

高效垂直流人工湿地在景观湖水循环净化中的应用--以天津东丽湖景观湖水循环净化工程为例

介绍了天津东丽湖景观湖水循环净化工程的工艺流程、运行工况,并对处理效果及景观湖水质进行了分析,对人工湿地系统及景观湖泊的管理和维护进行了总结.通过近1a的运行实践表明高效垂直流人工湿地系统作为一种生态水处理技术,对微污染地表水净化具有良好的实用价值和应用前景.     

水质自动监测系统常用维护措施及问题探讨

水质在线自动监测系统是一套综合性自动监测仪器,在一些污染较严重的河段,为保证系统在无人监控的情况下自动运行,各仪器的日常维护成为设备正常运行的关键,从基础设施建设、分析仪器、辅助系统、采样系统等4个方面探讨了系统维护及运行中常见的问题,并给出了相应的改进措施.     

鸭河口水库水体总氮、总磷预测研究

根据鸭河口水库受纳点源及面源污染负荷情况，选择枯水期为预测时期，采用迪隆模型对鸭河口水库水体总氮、总磷进行预测研究，为鸭河口水库水质保持和富营养化防治提供基础数据。     

Use of genetic algorithms to select input variables in decision tree models for the prediction of benthic macroinvertebrates

Predicting freshwater organisms based on machine learning is becoming more and more reliable due to the availability of appropriate datasets, advanced modelling techniques and the continuously increasing capacity of computers. A database consisting of measurements collected at 360 sampling sites in non-navigable watercourses in Flanders was applied to predict the absence/presence of benthic macroinvertebrate taxa by means of decision trees. The measured variables were a combination of physical–chemical (temperature, pH, dissolved oxygen concentration, conductivity, total organic carbon, Kjeldahl nitrogen and total phosphorus), structural (granulometric analysis of the sediment, width, depth and flow velocity of the river) and two ecotoxicological variables. The predictive power of decision trees was assessed on the basis of the number of Correctly Classified Instances (CCI). A genetic algorithm was introduced to compare the predictive power of different sets of input variables for the decision trees. The number of input variables was reduced from 15 to 2–8 variables without affecting the predictive power of the decision trees significantly. Furthermore, reducing the number of input variables allowed to ease the identification of general data trends.     

铁路不同系统职工“三类人员”健康状况分析

为了做好运输一线职工的健康管理工作,选择车辆、车务、电务、工务和机务系统参加健康体检的职工,以其2015—2016年体检数据为研究资料,分析了各系统"三类人员"健康情况。结果表明,不同系统"三类人员"总胆固醇异常率为车辆系统最高(64.9%),车务系统最低(60.0%);低密度脂蛋白胆固醇异常率最高为机务系统(53.1%),车务系统最低(45.7%);高密度脂蛋白胆固醇异常率为车辆系统最高(32.2%),工务系统最低(22.1%);空腹血糖异常率最高为机务系统(47.6%),电务系统最低(39.6%);甘油三酯异常率为工务系统最高(69.0%),车务系统最低(65.8%);舒张压异常率最高为车辆系统(93.8%),车务系统最低(78.2%);收缩压异常率最高为车辆系统(80.8%),车务系统最低(68.6%)。     

Modeling freshwater fish distributions using multiscale landscape data: A case study of six narrow range endemics

Species distribution models (SDMs) have become integral tools in scientific research and conservation planning. Despite progress in the assessment of various statistical models for use in SDMs, little has been done in way of evaluating appropriate ecological models. In this paper, we evaluate the multiscale filter framework as a suitable theoretical model for predicting freshwater fish distributions in the upper Green River system (Ohio River drainage), USA. The spatial distributions of six fishes with contrasting biogeographies were modeled using boosted regression trees and multiscale landscape data. Species biogeography did not appear to affect predictive performance and all models performed well statistically with receiver operating characteristic area under the curve (AUC) ranging from 0.87 to 0.98. Predictive maps show accurate estimations of ranges for five of six species based on historical collections. The relative influence of each type of environmental feature and spatial scale varied markedly with between species. A hierarchical effect was detected for narrowly distributed species. These species were highly influenced by soil composition at larger spatial scales and land use/land cover (LULC) patterns at more proximal scales. Conversely, LULC pattern was the most influential feature for widely distributed at all spatial scales. Using multiscale data capable of capturing hierarchical landscape influences allowed production of accurate predictive models and provided further insight into factors controlling freshwater fish distributions.     

基于SEM的机务维修人员故意违章行为影响因素研究

为了能够解释和预测机务维修人员的故意违章行为,探究故意违章行为的作用机理,以计划行为理论为基础框架,增加个人需要、管理层态度及工作压力因素,并探究影响因素之间的作用关系.对398份机场和航空公司机务维修人员的问卷调查数据进行信度和效度分析,然后利用结构方程模型的方法对假设的因果关系模型进行验证,并得到标准化路径系数.结果表明:感知行为控制、工作压力及个人需要对违章动机的正向影响作用显著;管理层态度和主观规范通过行为态度的中介作用间接影响违章动机;违章动机对违章行为的正向影响作用显著.     

浙江省农村生活污水处理现状及其对策

基于浙江省67个县的农村生活污水处理设施的问卷调查结果,统计分析浙江农村生活污水处理设施现状,包括动力情况、处理工艺、执行标准、运维模式、经费来源等,并探讨分析了农村生活污水处理设施排放标准及运维管理的长效性.结果表明:目前浙江农村生活污水处理设施以中小规模(30～60 t·d-1)为主,约80％的设施采用了无动力厌氧+人工湿地处理技术,出水一般执行GB 18918-2002《城镇污水处理厂污染物排放标准》中的一级B标准,以村镇自管的运维模式为主,年均运维成本为1.3万元·座-1.从省级管理层面应加快制订符合浙江省情的农村生活污水处理设施排放标准,其指标项目数量不宜过多,指标限值可略宽于GB 18918-2002中的一级A标准;并应尽快形成针对责任主体、资金保障、第三方运维的农村生活污水处理设施长效管理机制.