In crop production systems,all operations such as seed bed preparation,etc.,must be accomplished on time,if yield reduction and low quality product are to be avoided.Therefore all operations in mechanized cropping pro...In crop production systems,all operations such as seed bed preparation,etc.,must be accomplished on time,if yield reduction and low quality product are to be avoided.Therefore all operations in mechanized cropping projects require precise scheduling,planning and management.The basic approach in all scheduling techniques is to form a network of activities and events relationships that graphically portrays the sequential relations between the tasks in a project.Such a network would as a powerful tool available a farm manager to plan,schedule,monitor and control a project.Since GERT（Graphical Evaluation and Review Technique） networks have most of advantages associated with networks and available system analyst in exact evaluation of certain types of networks,in this research it was used and mechanized wheat production system was simulated,modeled and analyzed.Critical activities,events and path were determined.Results showed that the network model was able to answer any statistic questions concerning with the project.Network models,particularly GERT networks are increasingly powerful tool for modeling,scheduling,planning,controlling,and analyzing of agricultural mechanization projects.展开更多
灾害、衍生和次生灾害及其相互耦合使得灾情恶化,作为灾害对抗力量的抢险、避险、控制的救险等措施使得灾害向灾情减轻的方向转化,本文对灾害的这一动态演化过程进行描述,建立一种综合考虑灾害的自然演化与抢险救灾行动的基于Bayes推理...灾害、衍生和次生灾害及其相互耦合使得灾情恶化,作为灾害对抗力量的抢险、避险、控制的救险等措施使得灾害向灾情减轻的方向转化,本文对灾害的这一动态演化过程进行描述,建立一种综合考虑灾害的自然演化与抢险救灾行动的基于Bayes推理的灾害演化GERT(Graph Evaluation and Review Technique)网络模型;把GERT网络方法和贝叶斯推理工具相结合,根据获得的新信息,对GERT网络中活动参数进行动态修正,对灾害的演化路径,各种主要状态的演化概率和时间进行动态预测、预警与评价;对衍生与次生灾害、抢险救灾行动等外界行为对系统演化的影响进行定性与定量分析,并给出定量评价结论。本文提供了灾害演化定性与定量结合的分析框架与工具,揭示灾害演化机理,为灾害发展态势的预测、预警与评价提供了一种新的研究方法和研究思路。展开更多
针对装备寿命试验中失效样本量比较小的情形,基于应力冲击思想,提出了一种基于失效选择机制的装备系统可靠性评估定量分析方法。首先引入图示评审技术(Graphic evaluation and review technique,GERT)表征系统的多种工作状态和状态间的...针对装备寿命试验中失效样本量比较小的情形,基于应力冲击思想,提出了一种基于失效选择机制的装备系统可靠性评估定量分析方法。首先引入图示评审技术(Graphic evaluation and review technique,GERT)表征系统的多种工作状态和状态间的传递关系,根据系统结构进行可靠性评估建模。然后基于失效观测数据对元器件的可靠性进行估计,确定可靠性评估GERT网络中的参数。最后依据失效选择机制对网络进行计算,实现系统可靠性的评估。算例研究结果表明了基于失效选择机制的装备可靠性评估GERT模型的有效性。展开更多
文摘In crop production systems,all operations such as seed bed preparation,etc.,must be accomplished on time,if yield reduction and low quality product are to be avoided.Therefore all operations in mechanized cropping projects require precise scheduling,planning and management.The basic approach in all scheduling techniques is to form a network of activities and events relationships that graphically portrays the sequential relations between the tasks in a project.Such a network would as a powerful tool available a farm manager to plan,schedule,monitor and control a project.Since GERT（Graphical Evaluation and Review Technique） networks have most of advantages associated with networks and available system analyst in exact evaluation of certain types of networks,in this research it was used and mechanized wheat production system was simulated,modeled and analyzed.Critical activities,events and path were determined.Results showed that the network model was able to answer any statistic questions concerning with the project.Network models,particularly GERT networks are increasingly powerful tool for modeling,scheduling,planning,controlling,and analyzing of agricultural mechanization projects.
文摘灾害、衍生和次生灾害及其相互耦合使得灾情恶化,作为灾害对抗力量的抢险、避险、控制的救险等措施使得灾害向灾情减轻的方向转化,本文对灾害的这一动态演化过程进行描述,建立一种综合考虑灾害的自然演化与抢险救灾行动的基于Bayes推理的灾害演化GERT(Graph Evaluation and Review Technique)网络模型;把GERT网络方法和贝叶斯推理工具相结合,根据获得的新信息,对GERT网络中活动参数进行动态修正,对灾害的演化路径,各种主要状态的演化概率和时间进行动态预测、预警与评价;对衍生与次生灾害、抢险救灾行动等外界行为对系统演化的影响进行定性与定量分析,并给出定量评价结论。本文提供了灾害演化定性与定量结合的分析框架与工具,揭示灾害演化机理,为灾害发展态势的预测、预警与评价提供了一种新的研究方法和研究思路。
文摘针对装备寿命试验中失效样本量比较小的情形,基于应力冲击思想,提出了一种基于失效选择机制的装备系统可靠性评估定量分析方法。首先引入图示评审技术(Graphic evaluation and review technique,GERT)表征系统的多种工作状态和状态间的传递关系,根据系统结构进行可靠性评估建模。然后基于失效观测数据对元器件的可靠性进行估计,确定可靠性评估GERT网络中的参数。最后依据失效选择机制对网络进行计算,实现系统可靠性的评估。算例研究结果表明了基于失效选择机制的装备可靠性评估GERT模型的有效性。
