A structure scheme for a novel hybrid machine tool (HMT) is proposed in this paper. In the scheme,a 4-DOFs 1PS+3TPS type spatial hybrid mechanism is utilized as main feed mechanism,with assistance of a two direction m...A structure scheme for a novel hybrid machine tool (HMT) is proposed in this paper. In the scheme,a 4-DOFs 1PS+3TPS type spatial hybrid mechanism is utilized as main feed mechanism,with assistance of a two direction movable worktable,multi-coordinates NC machining can be realized. In the main feed mechanism,fixed platform is connected with moving platform by three TPS driving links and one PS driving link,one translation DOF and three rotation DOFs can be achieved by it. This type HMT enjoys some advantages over its conventional counterparts:large workspace,good dexterity,etc. Closed form inverse displacement analysis model and inverse kinematic model for main feed mechanism are established. A fuzzy PID control scheme for machining control of HMTs with high tracking precision is proposed aiming at highly nonlinear,tightly coupled and uncertain characteristic of HMTs. Simulation researches for fuzzy PID control of HMTs are carried out. Simulation Results demonstrate the effectiveness and the Robostness of the fuzzy PID controller.展开更多
The Internet Control Message Protocol(ICMP)covert tunnel refers to a network attack that encapsulates malicious data in the data part of the ICMP protocol for transmission.Its concealment is stronger and it is not eas...The Internet Control Message Protocol(ICMP)covert tunnel refers to a network attack that encapsulates malicious data in the data part of the ICMP protocol for transmission.Its concealment is stronger and it is not easy to be discovered.Most detection methods are detecting the existence of channels instead of clarifying specific attack intentions.In this paper,we propose an ICMP covert tunnel attack intent detection framework ICMPTend,which includes five steps:data collection,feature dictionary construction,data preprocessing,model construction,and attack intent prediction.ICMPTend can detect a variety of attack intentions,such as shell attacks,sensitive directory access,communication protocol traffic theft,filling tunnel reserved words,and other common network attacks.We extract features from five types of attack intent found in ICMP channels.We build a multi-dimensional dictionary of malicious features,including shell attacks,sensitive directory access,communication protocol traffic theft,filling tunnel reserved words,and other common network attack keywords.For the high-dimensional and independent characteristics of ICMP traffic,we use a support vector machine(SVM)as a multi-class classifier.The experimental results show that the average accuracy of ICMPTend is 92%,training ICMPTend only takes 55 s,and the prediction time is only 2 s,which can effectively identify the attack intention of ICMP.展开更多
As the foundation of an industrialized country nowadays,machine tools industry is regarded as the engine of industrial development of a country.The developed countries,such as USA,Germany and Japan,have widely deploye...As the foundation of an industrialized country nowadays,machine tools industry is regarded as the engine of industrial development of a country.The developed countries,such as USA,Germany and Japan,have widely deployed the technology of using the patent in order to keep their strength in various fields.This research examins the CNC machine tools industry in the world by using the patent analysis method.It first gives an overview about the world patent application in CNC machine tools industry from 1963 to 2010 and divides the development of the industry into five stages.It also lists the patent application of the world top 20 countries,where the top 5 countries are compared.The patents of the world top 10 companies of machine tools manufacturers are mapped according to the international patent classification(IPC),and the future trends of world machine tools industry are discussed.Finally conclusions and suggestions are presented.展开更多
基于二维Markov链的瞬时分析理论提出了一种研究控制器局域网(Controller Area Network,CAN)中周期性报文传输的解析模型。通过与仿真环境中周期性报文传输统计数据的对比,验证了建立该模型的相关假设与各项参数设置的正确性及模型的有...基于二维Markov链的瞬时分析理论提出了一种研究控制器局域网(Controller Area Network,CAN)中周期性报文传输的解析模型。通过与仿真环境中周期性报文传输统计数据的对比,验证了建立该模型的相关假设与各项参数设置的正确性及模型的有效性。该模型可用于分析CAN网络中时间触发的周期性报文的传输可能造成的阻塞延时。展开更多
文摘A structure scheme for a novel hybrid machine tool (HMT) is proposed in this paper. In the scheme,a 4-DOFs 1PS+3TPS type spatial hybrid mechanism is utilized as main feed mechanism,with assistance of a two direction movable worktable,multi-coordinates NC machining can be realized. In the main feed mechanism,fixed platform is connected with moving platform by three TPS driving links and one PS driving link,one translation DOF and three rotation DOFs can be achieved by it. This type HMT enjoys some advantages over its conventional counterparts:large workspace,good dexterity,etc. Closed form inverse displacement analysis model and inverse kinematic model for main feed mechanism are established. A fuzzy PID control scheme for machining control of HMTs with high tracking precision is proposed aiming at highly nonlinear,tightly coupled and uncertain characteristic of HMTs. Simulation researches for fuzzy PID control of HMTs are carried out. Simulation Results demonstrate the effectiveness and the Robostness of the fuzzy PID controller.
基金This research was supported by National Natural Science Foundation of China(Grant Nos.61972048,62072051).
文摘The Internet Control Message Protocol(ICMP)covert tunnel refers to a network attack that encapsulates malicious data in the data part of the ICMP protocol for transmission.Its concealment is stronger and it is not easy to be discovered.Most detection methods are detecting the existence of channels instead of clarifying specific attack intentions.In this paper,we propose an ICMP covert tunnel attack intent detection framework ICMPTend,which includes five steps:data collection,feature dictionary construction,data preprocessing,model construction,and attack intent prediction.ICMPTend can detect a variety of attack intentions,such as shell attacks,sensitive directory access,communication protocol traffic theft,filling tunnel reserved words,and other common network attacks.We extract features from five types of attack intent found in ICMP channels.We build a multi-dimensional dictionary of malicious features,including shell attacks,sensitive directory access,communication protocol traffic theft,filling tunnel reserved words,and other common network attack keywords.For the high-dimensional and independent characteristics of ICMP traffic,we use a support vector machine(SVM)as a multi-class classifier.The experimental results show that the average accuracy of ICMPTend is 92%,training ICMPTend only takes 55 s,and the prediction time is only 2 s,which can effectively identify the attack intention of ICMP.
基金Supported by Scientific Monitoring and Key Areas in-Depth Investigation and Research(No.ZD2012-4-2)Special Project of Scientific and Technological Basic Works(No.2009FY241000)Science and Technology Major Specific Project Core Electronic Elements,High-General Chips and Basic Software(No.2013XM01)
文摘As the foundation of an industrialized country nowadays,machine tools industry is regarded as the engine of industrial development of a country.The developed countries,such as USA,Germany and Japan,have widely deployed the technology of using the patent in order to keep their strength in various fields.This research examins the CNC machine tools industry in the world by using the patent analysis method.It first gives an overview about the world patent application in CNC machine tools industry from 1963 to 2010 and divides the development of the industry into five stages.It also lists the patent application of the world top 20 countries,where the top 5 countries are compared.The patents of the world top 10 companies of machine tools manufacturers are mapped according to the international patent classification(IPC),and the future trends of world machine tools industry are discussed.Finally conclusions and suggestions are presented.
文摘基于二维Markov链的瞬时分析理论提出了一种研究控制器局域网(Controller Area Network,CAN)中周期性报文传输的解析模型。通过与仿真环境中周期性报文传输统计数据的对比,验证了建立该模型的相关假设与各项参数设置的正确性及模型的有效性。该模型可用于分析CAN网络中时间触发的周期性报文的传输可能造成的阻塞延时。
