The current research of seawater hydraulic motor mainly focused on piston motor and vane motor, but seldom regarded low speed high torque seawater hydraulic motor. Low speed high torque seawater hydraulic motor as a k...The current research of seawater hydraulic motor mainly focused on piston motor and vane motor, but seldom regarded low speed high torque seawater hydraulic motor. Low speed high torque seawater hydraulic motor as a kind of energy conversion device and actuator plays an important role in seawater hydraulic transmission system. However, the physical and chemical properties of seawater, such as low viscosity, high causticity and poor lubrication, result in numerous problems. In this paper, the flow distribution characteristics of port plate pairs for the seawater hydraulic motor are investigated, and the leakage flow and power loss models of port plate pairs are established. Numerical simulations are carried out to examine the effects of water film, inlet pressure and rotating speed on the pressure distribution and leakage flow. And the friction and wear tests of port plate pairs are also carried out. Moreover, the test system of the seawater hydraulic motor is constructed and the performance of prototype with no-load or loading is conducted. The results indicate that the clearance of port plate pairs and inlet pressure have a significant effect on distribution characteristics, but the effect of rotating speed is not very obvious. The experimental results show that the minimum error rate can be maintained within 0.3% by the proposed flow model and the counter materials of 316 L against carbon-fiber-reinforced polyetheretherketone(CFRPEEK) are suitable for the port plate pairs of seawater hydraulic motor. Finally, based on the seawater hydraulic experiment platform, the volumetric efficiency of no-load and loading are obtained that the maximum can achieve 94.71% and 90.14%, respectively. This research work may improve the flow distribution performance, lubrication and the friction and wear properties, enhance energy converting efficiency of port plate pair and provide theoretical and technical support for the design of highperformance water hydraulic components.展开更多
Anomaly detection is now very important in the network because the increasing use of the internet and security of a network or user is a main concern of any network administrator. As the use of the internet increases,...Anomaly detection is now very important in the network because the increasing use of the internet and security of a network or user is a main concern of any network administrator. As the use of the internet increases, so the chances of having a threat or attack in the network are also increasing day by day and traffic in the network is also increasing. It is very difficult to analyse all the traffic data in network for finding the anomaly in the network and sampling provides a way to analyse the anomalies in network with less traffic data. In this paper, we propose a port scan detection approach called CPST uses connection status and pattern of the connections to detect a particular source is scanner or benign host. We also show that this approach works efficiently under different sampling methods.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51505111,51805125)Zhejiang Provincial National Natural Science Foundation of China(Grant No.LQ16E050003)+1 种基金Hebei Provincial National Natural Science Foundation of China(Grant No.E2015203006)Open Foundation of State Key Laboratory of Fluid Power and Mechatronic Systems(Grant No.GZKF-201519)
文摘The current research of seawater hydraulic motor mainly focused on piston motor and vane motor, but seldom regarded low speed high torque seawater hydraulic motor. Low speed high torque seawater hydraulic motor as a kind of energy conversion device and actuator plays an important role in seawater hydraulic transmission system. However, the physical and chemical properties of seawater, such as low viscosity, high causticity and poor lubrication, result in numerous problems. In this paper, the flow distribution characteristics of port plate pairs for the seawater hydraulic motor are investigated, and the leakage flow and power loss models of port plate pairs are established. Numerical simulations are carried out to examine the effects of water film, inlet pressure and rotating speed on the pressure distribution and leakage flow. And the friction and wear tests of port plate pairs are also carried out. Moreover, the test system of the seawater hydraulic motor is constructed and the performance of prototype with no-load or loading is conducted. The results indicate that the clearance of port plate pairs and inlet pressure have a significant effect on distribution characteristics, but the effect of rotating speed is not very obvious. The experimental results show that the minimum error rate can be maintained within 0.3% by the proposed flow model and the counter materials of 316 L against carbon-fiber-reinforced polyetheretherketone(CFRPEEK) are suitable for the port plate pairs of seawater hydraulic motor. Finally, based on the seawater hydraulic experiment platform, the volumetric efficiency of no-load and loading are obtained that the maximum can achieve 94.71% and 90.14%, respectively. This research work may improve the flow distribution performance, lubrication and the friction and wear properties, enhance energy converting efficiency of port plate pair and provide theoretical and technical support for the design of highperformance water hydraulic components.
文摘Anomaly detection is now very important in the network because the increasing use of the internet and security of a network or user is a main concern of any network administrator. As the use of the internet increases, so the chances of having a threat or attack in the network are also increasing day by day and traffic in the network is also increasing. It is very difficult to analyse all the traffic data in network for finding the anomaly in the network and sampling provides a way to analyse the anomalies in network with less traffic data. In this paper, we propose a port scan detection approach called CPST uses connection status and pattern of the connections to detect a particular source is scanner or benign host. We also show that this approach works efficiently under different sampling methods.
