开关电源模块可靠性的研究

本文分析了某军用开关电源模块的工作原理以及关键点波形,找出了开关电源模块中易于失效的关键元件,提出了目前开关电源发展所面临的可靠性寿命评价的关键问题。     

环境水体中肠道病原细菌定量PCR检测与膜过滤分析方法的比较

采用通用引物,通过实时荧光定量PCR方法(QPCR),对西安市5个地表水体中肠道病原细菌的细胞密度进行了分析.检测水样体积为100mL,分别于2006年3～6月取自水源水(黑河)、景观娱乐用水(大唐芙蓉园北湖和兴庆湖)、纳污河(浐河)和未消毒的二级出水(北石桥污水处理厂),并将QPCR检测结果与滤膜法(MF)测得的细菌总数、大肠菌群和粪大肠杆菌CFU结果进行了比较分析.5个水体(n=60)检测结果显示,QPCR检测结果是大肠菌群CFU的2.2～5倍,是粪大肠杆菌CFU的7～14倍.病原细菌检测的几何平均值范围,QPCR法在25～67000 CCE·100mL-1之间,MF法大肠菌群在3～45000 CFU·100mL-1之间,粪大肠菌群在0～3000 CFU·100mL-1之间(n=60).两种方法的检测结果使用Spearman秩相关法来计算,结果显示,QPCR检测结果与大肠菌群、细菌总数以及粪大肠杆菌CFU均呈现显著正相关,秩相关系数分别为r=0.983、r=0.908和r=0.948.     

Environmental,climate and social leadership of small enterprises: Fairphone’s step-by-step approach

ABSTRACT

Achieving sustainable consumption and production requires a break with current practices in many sectors, including the smartphone sector. Leaders are central actors in catalysing such change by developing, implementing and promoting innovative ideas, products and practices. Not only large but also small enterprises can aspire to assume leadership for sustainability. This contribution explores the environmental, climate and social leadership of the social enterprise Fairphone that seeks to start a movement towards a more sustainable smartphone sector. Endowed with barely any structural power, it relies on other leadership types, especially entrepreneurial leadership, which is based on dialogue, persuasion and coalition-building. Small enterprises can be leaders, but pursuing a goal such as transforming the smartphone sector takes a step-by-step approach targeting different follower groups from suppliers, competitors and consumers to end-of-life processors and policymakers. Those different follower groups are susceptible to different (combinations of) leadership types.     

变频调速PLC群控系统在消防供水系统中的应用

介绍了日本三菱公司生产的FXON60MR·PLC可编程控制器与FHF15K型变频器、SR70型智能PID控制器的组合在中原油气高新股份有限公司天然气处理厂消防供水系统中的应用。通过制定合理的控制方案实现了消防供水的全自动控制,并通过控制功能的设置实现较为复杂的系统开发和应用。     

城镇基础设施与环境的关系

城镇基础设施与城市环境关系越来越紧密,主要从给排水、供暖、交通、园林绿地等4方面,对城镇基础设施与环境的内在联系进行了分析.     

加油站新旧输油管线碰头焊接方法探讨

《汽车加油加气站设计与施工规范》(GB50156-2002)中提到加油站输油管道宜采用无缝钢管、连接方式采用焊接是输油管道敷设的基本要求,其优点是焊缝少、比较严密可靠、施工速度快、省材省工、便于防腐、不容易出现渗漏隐患。但加油站在改造输油管线时,新旧管线碰头焊接过程中产生的火花易点燃管线中的油气引发火灾及爆炸。因此,如何在新旧输油管线碰头焊接时安全施工就成为了需要我们探讨的问题。本文结合丹东太平湾加油站输油管线改造的实际情况,简要的阐述了加油站含油气管线碰头焊接的几种方法。     

基于图论的海洋平台连锁风险评价

为控制海洋平台连锁风险,基于图论(GT),提出一种新型定性风险评价方法,将分析对象的复杂风险分析转化为图形分析运算。该方法综合考虑研究对象的风险,重点考虑事故可能的发展模式,建立并转换可能发生的事故的连锁图,用图论算法进行图形运算,得到造成结果事故发生的关键路径、最短路径和点割集,设置并优化安全屏障,防止初始事故发生。最后,结合墨西哥湾事故,建立事故连锁图,通过图形变换与运算得到2条最短路径、3条关键路径和2个点割集,并提出风险控制措施。     

城市埋地燃气管道危险性SPA-Markov链评价预测模型

为对城市埋地燃气管道系统危险性进行动态评价及预测,为管理者提供更客观的、可靠的管理依据,将集对分析(SPA)理论和马尔科夫链相结合用于城市埋地燃气系统的动态评价中。针对城市埋地燃气管道系统存在不确定性和动态变化的特点,提出集状态评价和预测分析于一体的城市埋地燃气系统动态危险性评价预测方法。该方法利用SPA的多元联系数对系统的危险等级进行划分,运用马尔科夫链的遍历性,并将结果与集对势相结合,预测城市埋地燃气管道系统最终的危险水平。     

欧盟城市饮用水供应链风险管理与评价及其借鉴

结合欧盟2006年起开展的TECHNEAU(Technology Enabled Universal Access to Safe Water)项目,介绍了欧盟城市"从水源到用户的饮用水供应链"风险管理机制,以及"风险识别、评估、减缓和控制"综合风险评价框架;并从水源地、水处理系统、配水系统、历史风险事件、风险评价方法、评价结果6方面比较了捷克、德国、荷兰、挪威、瑞典5个国家典型城市风险评价实践,着重分析了瑞典哥特堡市风险评价中采用的综合概率故障树法和客户损失时间指数方法及其应用价值。总结了欧盟饮用水供应链的风险管理在全过程管理策略、"关口前移"管理方针、多样性的风险评价方法与技术、参与主体多元化、评价结果公开透明5个方面的成功做法和经验,可供国内参考。     

Economic benefits from food recovery at the retail stage: An application to Italian food chains

The food supply chain is affected by losses of products near to their expiry date or damaged by improper transportation or production defects. Such products are usually poorly attractive for the consumer in the target market even if they maintain their nutritional properties. On the other hand undernourished people face every day the problem of fulfilling their nutritional needs usually relying on non-profit organizations. In this field the food recovery enabling economic benefits for donors is nowadays seen as a coherent way to manage food products unsalable in the target market for various causes and thus destined to be discarded and disposed to landfill thus representing only a cost. Despite its obvious affordability the food recovery is today not always practiced because the economic benefits that could be achieved are barely known. The paper aims at presenting a deterministic mathematical model for the optimization of the supply chain composed by retailers and potential recipients that practice the food recovery, taking into account the benefits recognized to donors and the management costs of the food recovery. The model determines the optimal time to withdraw the products from the shelves as well as the quantities to be donated to the non-profit organizations and those to be sent to the livestock market maximizing the retailer profit. The results show that the optimal conditions ensuring the affordability of the food recovery strategy including the tax reliefs and cost saving for the retailers outperforms the profit achievable in absence of such a system.