The contract net protocol has developed to specify problem solving communication for nodes in a distributed problem solving. Task distribution is affected by a negotiation process,a discussion carried on between node...The contract net protocol has developed to specify problem solving communication for nodes in a distributed problem solving. Task distribution is affected by a negotiation process,a discussion carried on between nodes with tasks to he executed and nodes that may be able to execute those tasks. In contract net protocol,once negotiation successes,tbe task execution is assumed to success. However,in real world,even though a task is awarded to successfully bidding nodes,it may be delayed. Such delay may badly propagate in whole system. Here,we introduce real-time constraints into contract net protocol to manage task execution for avoiding the, task's delay,or even though being delayed,the railure cannot propagate to whole system. In this paper,we first present a real-time contract net protocol which is an extension of contract net protocol with real-time constraints for distributed computing. Our proposition extends the basic negotiation protocol to negotiation and controlling execution or task. The controlling process is based on task deadline time,we also present an extension of the internode language of contract net protocol specification with real-time constraints.展开更多
The practical engineering of satellite tracking telemetry and command(TT&C)is often disturbed by unpredictable external factors,including the temporary rise in a significant quantity of satellite TT&C tasks,te...The practical engineering of satellite tracking telemetry and command(TT&C)is often disturbed by unpredictable external factors,including the temporary rise in a significant quantity of satellite TT&C tasks,temporary failures and failures of some TT&C resources,and so on.To improve the adaptability and robustness of satellite TT&C systems when faced with uncertain dynamic disturbances,a hierarchical disturbance propagation mechanism and an improved contract network dynamic scheduling method for satellite TT&C resources were designed to address the dynamic scheduling problem of satellite TT&C resources.Firstly,the characteristics of the dynamic scheduling problem of satellite TT&C resources are analyzed,and a mathematical model is established with the weighted optimization objectives of maximizing the revenue from task completion and minimizing the degree of plan disturbance.Then,a bottom-up distributed dynamic collaborative scheduling framework for satellite TT&C resources is proposed,which includes a task layer,a resource layer,a central internal collaboration layer,and a central external collaboration layer.Dynamic disturbances are propagated layer by layer from the task layer to the central external collaboration layer in a bottom-up manner,using efficient heuristic strategies in the task layer and the resource layer,respectively.We use improved contract network algorithms in the center internal collaboration layer and the center external collaboration layer,the original scheduling plan is quickly adjusted to minimize the impact of disturbances while effectively completing dynamic task requirements.Finally,a large number of simulation experiments were carried out and compared with various comparative algorithms.The results show that the proposed algorithm can effectively improve the solution effect of satellite TT&C resource dynamic scheduling problems,and has good application prospects.展开更多
This paper presents the network service model and protocol model, and gives a brief introduction to a high level Petri net called EPr/TN net system, which serves as the formal specification tool for network protocol....This paper presents the network service model and protocol model, and gives a brief introduction to a high level Petri net called EPr/TN net system, which serves as the formal specification tool for network protocol. Finally, the general methods for the展开更多
CAN BUS(controller area network)已被广泛应用到各个自动化控制系统中,他具有可靠性高、功能完善、成本合理的特点。但他没有对应用层协议作具体规定。CANopen和DeviceNET是一种开放的现场总线协议,他以CAN芯片为基础硬件制定出面向...CAN BUS(controller area network)已被广泛应用到各个自动化控制系统中,他具有可靠性高、功能完善、成本合理的特点。但他没有对应用层协议作具体规定。CANopen和DeviceNET是一种开放的现场总线协议,他以CAN芯片为基础硬件制定出面向工业自动化过程的应用层通信协议,在众多的工业控制领域具有广阔的应用前景。简析了CANopen与Device NET协议,并从网络参考模型、高层通信协议、软件流程、初始化组态、应用范围等方面做了比较。展开更多
针对.NET框架调用C++开发的医学数字影像通信DICOM(Digital Imaging and Communications in Medicine)工具库需要重新声明数据结构和函数,提出在.NET框架下开发DICOM工具库。在分析DICOM3.0协议定义的信息对象、数据字典、通信服务类、...针对.NET框架调用C++开发的医学数字影像通信DICOM(Digital Imaging and Communications in Medicine)工具库需要重新声明数据结构和函数,提出在.NET框架下开发DICOM工具库。在分析DICOM3.0协议定义的信息对象、数据字典、通信服务类、文件解析与传通功能之后,采用C#语言和面向对象技术设计并实现了工具库。实验表明减少了数据结构重定义和输出函数重声明的工作量,提高了PACS系统开发和实施效率。展开更多
文摘The contract net protocol has developed to specify problem solving communication for nodes in a distributed problem solving. Task distribution is affected by a negotiation process,a discussion carried on between nodes with tasks to he executed and nodes that may be able to execute those tasks. In contract net protocol,once negotiation successes,tbe task execution is assumed to success. However,in real world,even though a task is awarded to successfully bidding nodes,it may be delayed. Such delay may badly propagate in whole system. Here,we introduce real-time constraints into contract net protocol to manage task execution for avoiding the, task's delay,or even though being delayed,the railure cannot propagate to whole system. In this paper,we first present a real-time contract net protocol which is an extension of contract net protocol with real-time constraints for distributed computing. Our proposition extends the basic negotiation protocol to negotiation and controlling execution or task. The controlling process is based on task deadline time,we also present an extension of the internode language of contract net protocol specification with real-time constraints.
基金This work was supported in part by the National Natural Science Foundation of China(No.62373380).
文摘The practical engineering of satellite tracking telemetry and command(TT&C)is often disturbed by unpredictable external factors,including the temporary rise in a significant quantity of satellite TT&C tasks,temporary failures and failures of some TT&C resources,and so on.To improve the adaptability and robustness of satellite TT&C systems when faced with uncertain dynamic disturbances,a hierarchical disturbance propagation mechanism and an improved contract network dynamic scheduling method for satellite TT&C resources were designed to address the dynamic scheduling problem of satellite TT&C resources.Firstly,the characteristics of the dynamic scheduling problem of satellite TT&C resources are analyzed,and a mathematical model is established with the weighted optimization objectives of maximizing the revenue from task completion and minimizing the degree of plan disturbance.Then,a bottom-up distributed dynamic collaborative scheduling framework for satellite TT&C resources is proposed,which includes a task layer,a resource layer,a central internal collaboration layer,and a central external collaboration layer.Dynamic disturbances are propagated layer by layer from the task layer to the central external collaboration layer in a bottom-up manner,using efficient heuristic strategies in the task layer and the resource layer,respectively.We use improved contract network algorithms in the center internal collaboration layer and the center external collaboration layer,the original scheduling plan is quickly adjusted to minimize the impact of disturbances while effectively completing dynamic task requirements.Finally,a large number of simulation experiments were carried out and compared with various comparative algorithms.The results show that the proposed algorithm can effectively improve the solution effect of satellite TT&C resource dynamic scheduling problems,and has good application prospects.
文摘This paper presents the network service model and protocol model, and gives a brief introduction to a high level Petri net called EPr/TN net system, which serves as the formal specification tool for network protocol. Finally, the general methods for the
文摘CAN BUS(controller area network)已被广泛应用到各个自动化控制系统中,他具有可靠性高、功能完善、成本合理的特点。但他没有对应用层协议作具体规定。CANopen和DeviceNET是一种开放的现场总线协议,他以CAN芯片为基础硬件制定出面向工业自动化过程的应用层通信协议,在众多的工业控制领域具有广阔的应用前景。简析了CANopen与Device NET协议,并从网络参考模型、高层通信协议、软件流程、初始化组态、应用范围等方面做了比较。
文摘针对.NET框架调用C++开发的医学数字影像通信DICOM(Digital Imaging and Communications in Medicine)工具库需要重新声明数据结构和函数,提出在.NET框架下开发DICOM工具库。在分析DICOM3.0协议定义的信息对象、数据字典、通信服务类、文件解析与传通功能之后,采用C#语言和面向对象技术设计并实现了工具库。实验表明减少了数据结构重定义和输出函数重声明的工作量,提高了PACS系统开发和实施效率。
