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
本文构建了以特征函数和传递概率为传递函数的CF-GERT（characteristic function based GERT）模型，利用特征函数的性质，证明了CF-GERT网络串联结构、并联结构、自环结构的传递关系与信号流图等价传递参数计算完全相同，故可借鉴信号...本文构建了以特征函数和传递概率为传递函数的CF-GERT（characteristic function based GERT）模型，利用特征函数的性质，证明了CF-GERT网络串联结构、并联结构、自环结构的传递关系与信号流图等价传递参数计算完全相同，故可借鉴信号流图理论求解CF-GERT模型.考虑以梅森公式为基础的经典GERT解析算法需要分析复杂的网络拓扑结构，提出了CF-GERT网络的矩阵式表征方法，进而设计了CF-GERT的矩阵式求解算法，推导了期望、方差、等价特征函数的计算公式.若等价特征函数绝对可积，则利用傅里叶逆变换推导概率密度函数；否则，运用Fang等提出的COS方法推导.最后用两个案例说明了所提方法的有效性.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.
文摘本文构建了以特征函数和传递概率为传递函数的CF-GERT（characteristic function based GERT）模型，利用特征函数的性质，证明了CF-GERT网络串联结构、并联结构、自环结构的传递关系与信号流图等价传递参数计算完全相同，故可借鉴信号流图理论求解CF-GERT模型.考虑以梅森公式为基础的经典GERT解析算法需要分析复杂的网络拓扑结构，提出了CF-GERT网络的矩阵式表征方法，进而设计了CF-GERT的矩阵式求解算法，推导了期望、方差、等价特征函数的计算公式.若等价特征函数绝对可积，则利用傅里叶逆变换推导概率密度函数；否则，运用Fang等提出的COS方法推导.最后用两个案例说明了所提方法的有效性.
