承压设备风险分析中失效后果加权模型研究

在分析失效可能性和失效后果具有不同权重的特点的基础上,提出一种失效后果加权的风险计算模型,该模型的等风险曲线很好地描述风险矩阵中的风险等级分布,并很好地解释风险矩阵分布的非对称性。所建立的模型能连续地将风险等级区域划分开来,以数学模型的形式描述不同风险等级的边界线,解决了传统风险等风险线跨越不同风险级别区域的问题。根据失效后果加权模型的风险计算结果,分析失效后果的权重大于失效可能性的权重的特点。     

Reproductive health services for refugees by refugees: an example from Guinea

The need to involve refugees in their own reproductive health (RH) services has long been recognised, but there is a lack of published examples describing how this can be achieved collaboratively between refugee initiatives, UNHCR, bilateral development organisations and international relief agencies. This paper outlines the work, outputs and lessons learnt of the Reproductive Health Group (RHG), an organisation of Liberian and Sierra Leonean refugee midwives and laywomen providing RH services to fellow refugees in Guinea's Forest Region between 1996 and 2000. Working as part of the Guinean health system, RHG midwives and community facilitators helped make the RH services in their region the most effective in Guinea at the time. Looking at RHG's achievements, the challenges it faced and partly overcame, it is argued that refugee organisations can plan and implement RH services for refugees where UNHCR and its international partners ensure that they receive funding and technical assistance.     

堆载作用下埋地管道应力影响因素及失效荷载研究*

为探究地面堆载导致埋地油气管道失效的事故影响因素,通过对管道在堆载作用下的工程案例进行概化,以X70管道为研究对象,采用有限元软件建立管道在堆载作用下的三维模型,采用理论计算验证模型的可行性,开展管道应力与变形分析,探讨不同的堆载强度、管道埋设深度、下卧层土体杨氏模量、管道内压与堆载偏移距离对管道应力的影响,同时开展多因素耦合研究。研究结果表明:深埋管道会促进附加应力向两端扩散,管道中心部位以外的应力值呈现为深埋＞浅埋;当下卧层杨氏模量大于20 MPa后,管道偏于安全;内压在0~2 MPa时,可以抵消部分堆载对管道的影响,内压大于2 MPa后,管道应力整体增大,此时管道应力由内压主导;得到不同管道埋深与不同下卧层土体杨氏模量耦合工况下X70管道失效时的堆载强度。研究结果可为埋地管道在堆载作用下的安全防护问题提供参考。     

基于故障树理论的舰船海水管系腐蚀失效原因分析及应用

针对某型船板式冷却器B10海水管路频繁穿孔漏水问题,本文基于故障树分析理论,以故障海水管路的腐蚀环境、腐蚀形貌和腐蚀机理为层次,将可能导致海水管路穿孔漏水的各种因素作为底事件列出,通过逻辑联系形成上述问题管路的故障树模型。在逐一分析故障树各项底事件的发生原因和典型表现后,将故障原因定位为B10管路与冷却器钛合金板片之间发生异种金属电偶腐蚀,并进行了原理复现,以验证分析的正确性,最终提出包括增加电绝缘组件在内的一系列治理措施,在船上实施后,取得了较好的治理效果。该分析方法可为各类舰船海水管路腐蚀问题的分析定位和治理防护提供借鉴。     

在役晶体管湿热试验失效模式及机理研究

目的 研究在役晶体管湿热试验的失效模式及失效机理,为减少晶体管失效提出改进建议。方法 选取长期贮存了10余年未失效的3型在役晶体管进行湿热环境试验,采用扫描电镜观测、电性能参数测试、离子色谱分析等方法研究晶体管失效的模式和失效机理。结果 晶体管经过2160h湿热试验后,有3.75%的晶体管发生失效,其中晶体管管腿断裂失效比例占2.50%,失效机理为应力腐蚀开裂;晶体管参数超标比例为1.25%,失效机理为器件背部或三防漆所含粘附离子引起的漏电。结论 湿热试验会加速在役晶体管的失效,其失效模式主要为因应力腐蚀开裂导致的管腿断裂以及因表面粘附离子引起的参数超差。建议在晶体管的寿命期内加强质量管理,改善不当的制管工艺,减少器件的内部缺陷及残余应力的存在,控制器件贮存环境的温湿度以及大气成分,杜绝氯离子等粘附离子及其他活性物质的引入。     

考虑螺栓断裂的固体导弹水平跌落安全性分析

目的 通过数值仿真分析水平跌落条件下的固体导弹安全性。方法 基于LS-DYNA进行全弹水平跌落仿真计算,通过位移和加速度的实验测量值进行模型校核。重点分析螺栓断裂对结果的影响,对比螺栓在不同建模方法、不同断裂数量下的仿真结果。基于经过校核的全弹模型,计算含能材料的应力场。结果 不同建模方法中,螺栓连接法的加速度峰值计算精度最高;不同工况之中,三部段工况下的螺栓断裂数量与实际一致,且加速度峰值计算精度最高。根据精度最高的仿真模型计算出的全弹应力响应,战斗部与发动机装药内部最大Von Mises应力均小于反应阈值。结论 螺栓连接的建模方法和断裂数量对于全弹位移、加速度的计算精度具有显著影响。采用螺栓连接法建模的三部段工况仿真模型最为可靠。基于可靠模型的含能材料应力场计算结果表明,全弹6 m水平跌落不会直接引起战斗部、发动机装药反应。     

某型直升机高可靠集成式通用自动测试系统的研制

目的 研制某型直升机电子产品通用自动测试系统,通过自动检测快速隔离各系统电子产品故障,加快故障修复,保障装备的完好率。方法 在充分分析故障损伤原因、类型、影响以及各系统电子产品测试需求、测试信号、性能特征的基础上,利用国内外先进的自动测试技术、总线技术、虚拟仪器技术、面向信号的软件架构及编程语言技术等,完成通用自动测试系统软硬件平台的设计与开发。结果 采用VXI、GPIB、1553B、LAN等多种总线仪器,在满足测试需求的前提下,减小了自动测试系统的体积。采用虚拟仪器技术,实现了测试程序与硬件资源的无关性,使用面向信号的ATLAS语言编写测试程序,方便移植,提高了测试程序的开发效率。结论 通过长时间的使用验证,该自动测试系统可完成某型直升机各系统电子产品的功能检查、性能检测及服役故障隔离,通用性、集成性、可靠性、耐久性、操作性强,还有一定机动性,适用于各种地面环境装备保障任务。     

Association of reproductive traits with captive- versus wild-sourced birds in trade

The wildlife trade is a billion-dollar global business, involving millions of people, thousands of species, and hundreds of millions of individual organisms. Unravelling whether trade targets reproductively distinct species and whether this preference varies between captive- and wild-sourced species is a crucial question. We used a comprehensive list of all bird species traded, trade listings and records kept in compliance with the Convention on International Trade in Endangered Species (CITES), and a suite of avian reproductive parameters to examine whether wildlife trade is associated with particular facets of life history and to examine the association between life-history traits and captive- and wild-sourced traded volumes over time. Across all trade, CITES listing, and CITES trade, large birds were more likely to be traded and listed, but their longevity and age at maturity were not associated with CITES listing or trade. We found species across almost the full range of trait values in both captive and wild trade between 2000 and 2020. Captive trade volumes clearly associated with relatively longer lived and early-maturing species; these associations remained stable and largely unchanged over time. Trait–volume associations in wild-sourced trade were more uncertain. Only body mass had a clear association, and it varied from negative to positive over time. Although reproductive traits were important in captive-sourced trade, species-level variation dominated trade, with even congeneric species varying greatly in volume despite similar traits. The collection and incorporation of trait data into sustainability assessments of captive breeding facilities are crucial to ensure accurate quotas and guard against laundering.     

Modeling genetic benefits and financial costs of integrating biobanking into the conservation breeding of managed marsupials

Managed breeding programs are an important tool in marsupial conservation efforts but may be costly and have adverse genetic effects in unavoidably small captive colonies. Biobanking and assisted reproductive technologies (ARTs) could help overcome these challenges, but further demonstration of their potential is required to improve uptake. We used genetic and economic models to examine whether supplementing hypothetical captive populations of dibblers (Parantechinus apicalis) and numbats (Myrmecobius fasciatus) with biobanked founder sperm through ARTs could reduce inbreeding, lower required colony sizes, and reduce program costs. We also asked practitioners of the black-footed ferret (Mustela nigripes) captive recovery program to complete a questionnaire to examine the resources and model species research pathways required to develop an optimized biobanking protocol in the black-footed ferret. We used data from this questionnaire to devise similar costed research pathways for Australian marsupials. With biobanking and assisted reproduction, inbreeding was reduced on average by between 80% and 98%, colony sizes were on average 99% smaller, and program costs were 69- to 83-fold lower. Integrating biobanking made long-standing captive genetic retention targets possible in marsupials (90% source population heterozygosity for a minimum of 100 years) within realistic cost frameworks. Lessons from the use of biobanking technology that contributed to the recovery of the black-footed ferret include the importance of adequate research funding (US$4.2 million), extensive partnerships that provide access to facilities and equipment, colony animals, appropriate research model species, and professional and technical staff required to address knowledge gaps to deliver an optimized biobanking protocol. Applied research investment of A$133 million across marsupial research pathways could deliver biobanking protocols for 15 of Australia's most at-risk marsupial species and 7 model species. The technical expertise and ex situ facilities exist to emulate the success of the black-footed ferret recovery program in threatened marsupials using these research pathways. All that is needed now for significant and cost-effective conservation gains is greater investment by policy makers in marsupial ARTs.     

Introducing a common taxonomy to support learning from failure in conservation

Although some sectors have made significant progress in learning from failure, there is currently limited consensus on how a similar transition could best be achieved in conservation and what is required to facilitate this. One of the key enabling conditions for other sectors is a widely accepted and standardized classification system for identifying and analyzing root causes of failure. We devised a comprehensive taxonomy of root causes of failure affecting conservation projects. To develop this, we solicited examples of real-life conservation efforts that were deemed to have failed in some way, identified their underlying root causes of failure, and used these to develop a generic, 3-tier taxonomy of the ways in which projects fail, at the top of which are 6 overarching cause categories that are further divided into midlevel cause categories and specific root causes. We tested the taxonomy by asking conservation practitioners to use it to classify the causes of failure for conservation efforts they had been involved in. No significant gaps or redundancies were identified during this testing phase. We then analyzed the frequency that particular root causes were encountered by projects within this test sample, which suggested that some root causes were more likely to be encountered than others and that a small number of root causes were more likely to be encountered by projects implementing particular types of conservation action. Our taxonomy could be used to improve identification, analysis, and subsequent learning from failed conservation efforts, address some of the barriers that currently limit the ability of conservation practitioners to learn from failure, and contribute to establishing an effective culture of learning from failure within conservation.