Respiratory mode and gear type are important determinants of elasmobranch immediate and post‐release mortality

Estimated declines in shark and ray populations worldwide have raised major, widespread concern about the impacts of global fisheries on elasmobranchs. The mechanisms causing elasmobranch mortality during fisheries’ capture are not fully understood, but we must gain greater clarity on this topic for fisheries managers to develop effective conservation plans to mitigate further population declines. To evaluate how two important factors, respiratory mode and fishing gear type, impact elasmobranch survival, we compiled publicly available data sources on the immediate mortality percentages of 83 species and post‐release mortality percentages of 40 species. Using Bayesian models, we found that sharks and rays captured in longlines had significantly lower immediate mortality than those caught in trawls or gillnets. Our models also predicted the mean total discard mortality (combined immediate and post‐release mortality) percentages of obligate ram‐ventilating elasmobranchs caught in longline, gillnet and trawl gear types to be 49.8, 79.0 and 84.2%, respectively. In contrast, total discard mortality percentages of stationary‐respiring species were significantly lower (longline capture mean = 7.2%, gillnet capture mean = 25.3%, trawl capture mean = 41.9%). Our global meta‐analysis provides the first quantified demonstration of how mortality is affected by these two factors across a broad range of species. Our results and approach can be applied to data‐deficient elasmobranchs and fisheries to identify species that are likely to experience high rates of mortality due to respiratory mode and/or fishing methods used, so that appropriate mitigation measures can be prioritized and investigated.     

福建海洋捕捞"技术效率"的时间序列分析

根据1981-2003年福建省渔业统计及相关调查资料，应用DEA法，分析了全省海洋捕捞作业及五种主要作业捕捞“技术效率”的年间变化，结果表明：1981～2003年全省海洋捕捞作业综合“技术效率”的变化范围为61．8％～100%，平均为76．4％，综合“技术效率”的年间变化呈现先降后升的态势；1990年以来，全省灯光围网和张网作业捕捞能力的发挥比较好，其次为刺网和底拖网作业，钓具作业捕捞能力的发挥较差；渔获选择性低的底拖网和张网作业的捕捞“技术趋势”年间变化保持平稳上升，渔获选择性高或较高的刺网、钓具和灯光围网作业的捕捞“技术趋势”年间变化则呈波动式上升或处于波动状态；各种投入因子对不同作业类型的捕捞”技术效率”的约束力各不相同，主动性较大的底拖网和灯光围网作业对渔船功率的依赖程度相当大，而主动性较小的刺网、钓具作业和被动性的张网作业，对网(钓)具使用数量的依赖度较大；作业天数对五种作业类型的“技术效率”发挥都有不同程度的影响。     

输油管道运行参数及检测数据的统计分析

统计了某输油管道运行压力和温度、腐蚀检测数据以及管材性能等数据,并进行了分析.对于管道运行温度和压力,推荐了概率分布;对于腐蚀缺陷的深度和长度,分别推荐了指数分布和对数正态分布.拟合腐蚀检测数据,得到了缺陷深度和长度的统计特征值.对管材性能参数推荐采用正态分布,这种分布在95%的置信度下可通过假设检验.认为该输油管道的统计分析结果可以作为输油管道安全评定的基础.     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

美国林业产业投资基金运行模式与经验借鉴

林业产业投资基金是美国林业金融体系的重要一环,对提升美国林地的资产价值发挥着重要作用;而我国2017年才成立了第1支林业产业投资基金,其运行处于起步探索阶段,投资模式和盈利机制尚不成熟。文中通过介绍美国林业产业投资基金基本情况,分析其运作模式、主要特点和成功要素,以期为我国林业产业投资基金的顺利运行提供参考和建议。     

浅谈校园电子商务系统的建设与运营

本文在分析研究校园电子商务系统建设经验的基础上,建立了一套基于高校现有的网络资源和计算机软件、硬件条件的校园电子商务系统,提出了系统建设的策略与运营推广方案。     

农业生产托管保障国家粮食安全的理论分析——基于生成逻辑的视角

农业生产托管作为社会化服务主要服务方式和经营方式,是实现小农户与现代农业发展有机衔接的重要路径,对于保障国家粮食安全具有重要意义。从现实背景和政策要求出发,基于生成逻辑的视角,分析农业生产托管保障国家粮食安全的内在机理,探讨农业生产托管存在的主要问题,提出农业生产托管保障国家粮食安全的推进策略。研究表明,农业生产托管的生成逻辑由逻辑基础、生成条件、表现形式、主要目的、重要前提等内容构成,在稳定产权关系、提高生产效率、减少要素投入、降低成本与风险、提高机械化与信息化水平等方面对保障国家粮食安全具有重要作用。但是,农业生产托管面临服务体系不健全、供需矛盾问题突出、服务对象定位不清晰、服务组织积极性不足等问题。因此,提出建立新型粮食生产托管服务体系、提高粮食生产托管服务组织服务能力、推动小农户积极参与、完善粮食生产托管政策支持方式等推进农业生产托管发展的建议。     

牦牛永久性瘤胃试验瘘管安置术

[目的]为研究反刍动物的消化功能提供参考。[方法]于2005年4月~2006年5月采用自创手术对15头2~3岁、体重为90~250kg的牦牛进行永久性人造瘤胃试验瘘管安置。[结果]手术后,所有施术牦牛精神状态、体温及食欲等方面均表现正常。7 d后检查发现,全部施术牦牛的瘤胃壁都与腹膜、腹肌及皮肤愈合在一起,形成自然瘘管,没有出现腹腔感染的现象。安置的的瘤胃试验瘘管都保持到1.5年以上。[结论]该手术方法具有过程简单,可操作性强,瘘管不易滑脱,密闭性好,创口恢复快、无感染,没有瘤胃液渗出和感染现象等优点,术后牦牛能正常存活,可长期用于试验。     

基于支持向量机的电气设备运行状态图像识别方法研究

针对电气设备运行状态图像的特点,提出将支持向量机（SVM）分类器应用于多种电气设备运行状态识别中。首先利用C-均值聚类法,分割出运行状态指示牌的汉字或数字部分;再利用K—L变换提取出运行状态的特征向量;最后利用支持向量机分类方法进行状态识别。试验结果表明：支持向量机分类方法对于小样本情况,具有良好的分类能力,适合多种电气设备运行状态的分类,并能获得比神经网络方法更好的识别性能。不同的分类核函数的相互比较分析表明,Sigmoid核函数最适合电气设备运行状态的分类识别。