水稻机械化直播优势、问题与发展对策

随着现代农业与农业机械化技术不断发展,传统水稻种植方式与技术越来越呈现出一定的不足,难以满足水稻高质量生产发展的需求,也与从事农业生产的农民利用农业机械减轻劳动强度、利用机械化生产节本增效的出发点不一致.从水稻机械化技术的相关问题着手,阐述了水稻机械化直播的现实性与必要性.     

生鲜电商物流现状、问题与发展趋势

为推动建立生鲜电商全程冷链物流体系,确保生鲜产品的质量安全,综合生鲜产品、电商、冷链物流等因素,对生鲜电商物流发展现状、存在问题及其挑战和机遇进行分析,以探求其发展趋势和方向。     

基于促进烟叶标准化生产持续性的思考

烟叶标准化生产是实现现代烟草农业发展的举措和支撑,是提高烟叶品质的保障。文章结合烟叶标准化生产实际,通过分析烟叶标准化生产过程中存在的主观意识淡薄、体系建设改进缓慢、队伍建设不够完善等问题,提出了应加大宣传力度、加强培训、完善激励机制等具体措施,以切实推进烟叶标准化生产的协调性和可持续发展。     

永和豆浆连锁经营成功模式探析

永和豆浆在迈向国际化发展进程中,成功的关键是实实在在的经营,能够满足消费者的需求,汲取应用更多的科技手段和管理经验,持续性地建设永和豆浆品种的标准化、生产的工厂化、经营的连锁规模化和管理的科学化,创造品牌生命力。     

2BFQ-4 型油菜精量联合直播机的研制

研制了一种与手扶拖拉机配套的2BFQ-4 型气力式油菜精量联合直播机。该机以正负气压组合式油菜 精量排种技术为核心、高度集成免耕开沟/种床旋耕灭茬、气力精量播种、施肥、覆土等机械化作业环节、可实现油菜 机械化精量联合直播作业、并能根据农艺要求进行播量调节。经检测、该机性能指标全部达到设计要求、有效实现了 农机与农艺的结合、综合效益明显、适应稻-油、棉-油种植的机械化油菜直播。     

生物质热解气燃烧装置设计与燃烧特性试验

针对目前生物质热解气中焦油去除困难、焦油能量难以利用等问题,结合现有燃气燃烧器相关技术,开展了生物质热解气直接燃烧技术研究与试验。燃烧器理论耗气量为2~5 m~3/h,通过理论计算确定了燃烧器参数,设计了卧式燃烧室并安装烟气催化裂解装置及烟气检测装置,搭建了热解气燃烧试验平台,并对热解气的燃烧特性进行了试验研究。以花生壳为原料,在碳化温度500℃、滞留时间30 min的条件下进行连续热解碳化,产生的高温热解气直接通入燃烧设备。结果表明,燃烧设备性能较好,热解气燃烧过程稳定,燃烧效率达到98.5%,在催化剂的作用下,燃烧效率提高到98.9%,满足设计要求。     

中小型水电站过电压的有关问题及其保护

针对电力系统中由于过电压使设备元件的绝缘损坏的情况在事故中所占比重很大的实际，根据造成中小型水电站雷害的3个主要来源，分析阐述了中小型水电站如何进行直击雷和雷电侵入波的防护等问题，介绍了中小型水电站主、副厂房和发电机避免雷击损害的保护方法。     

强化责任意识促进事业单位财务管理规范化

文章介绍了农业部管理干部学院做好财务工作的主要做法:一是抓好队伍建设,提高财务人员能力素质;二是抓制度建设,健全内部管理责任机制;三是抓风险防控,切实强化财务基础工作。     

Application of the Tweedie distribution to zero-catch data in CPUE analysis

We focus on the zero-catch problem of CPUE (catch per unit effort) standardization. Because the traditional CPUE model with a log-normal error structure cannot be applied in this case, three methods have often been utilized as follows:

(1) Ad hoc method adds a small constant value to all response variables.

(2) Catch model with a Poisson or negative-binomial (NB) error structure.

(3) Delta-type two-step method such as the delta-normal model (after estimating the ratio of zero-catch using a logit or probit model, a model such as CPUE log-normal or Catch-Poisson is applied to CPUE without zero-data).

However, there are some statistical problems with each of these methods.In this paper, we carried out the CPUE standardization mainly using the Tweedie distribution model based on the actual by-catch data (silky shark, Carcharhimus falciformis, in the North Pacific Ocean caught by Japanese training vessels) including many observations with zero-catch (>2/3rd) and tuna fishery data as a target (yellowfin tuna, Thunnus albacares, in the Indian Ocean caught by Japanese commercial vessels) where the ratio of zero-catch is not so high (<1/3rd). The Tweedie model is an extension of compound Poisson model derived from the stochastic process where the weight of the counted objects (i.e., number of fish) has a gamma distribution and has an advantage of handling the zero-catch data in a unified way.We also compared four candidate models, the Catch-NB model, ad hoc method, Delta-lognormal model (delta-type two-step method) and Tweedie distribution, through CPUE analyses of actual fishery data in terms of the statistical performance. Square error and Pearson's correlation coefficient were calculated based on the observed CPUE and the corresponding predicted CPUE using the n-fold cross-validation.As a result, the differences in the trend of CPUE between years and model performance between the ad hoc method and Tweedie model were found to be not so large in the example of yellowfin tuna (target species). However, the statistical performance of Tweedie distribution is rather better than Delta-lognormal model, the Catch-NB distribution and ad hoc method in the example of silky shark (by-catch species). Standardized CPUE year trend of ad hoc method was found to be quite different from that of the Tweedie distribution and other two models. Model performance of the Tweedie distribution is good judging from the 5-fold cross-validation using the fishery data if including many zero-catch data such as by-catch species.     

议机读书目数据标准化与规范化的作用

本文论述了机读书目数据标准化与规范化方面相关问题，编目工作只有严格遵循编目规则，遵循著录标准，才能提高书目数据乃至书目数据库的质量，从而为读者提供优质、高效的书目检索体系。有了标准，馆藏文献才有保障，读者检索才能方便，联机编目才能有保障。