We use the pruned-enriched Rosenbluth method to investigate systematically the segment density profiles of compact polymer chains confined between two parallel plane walls. The non-adsorption case of adsorption intera...We use the pruned-enriched Rosenbluth method to investigate systematically the segment density profiles of compact polymer chains confined between two parallel plane walls. The non-adsorption case of adsorption interaction energy ε = 0 and the weak adsorption case of ε= -1 are considered for the compact polymer chains with different chain lengths N and different separation distances between two walls D. Several special entropy effects on the confined compact polymer chains, such as a damped oscillation in the segment density profile for the large separation distance D, are observed and discussed for different separation distances D in the non-adsorption case. In the weak adsorption case, investigations on the segment density profiles indicate that the competition between the entropy and adsorption effects results in an obvious depletion layer. Moreover, the scaling laws of the damped oscillation period Td and the depletion layer width Ld are obtained for the confined compact chains. Most of these results are obtained for the first time so far as we know, which are expected to understand the properties of the confined compact polymer chains more completely.展开更多
The nonlinear stability of plane parallel shear flows with respect to tilted perturbations is studied by energy methods.Tilted perturbation refers to the fact that perturbations form an angleθ∈(0,π/2)with the direc...The nonlinear stability of plane parallel shear flows with respect to tilted perturbations is studied by energy methods.Tilted perturbation refers to the fact that perturbations form an angleθ∈(0,π/2)with the direction of the basic flows.By defining an energy functional,it is proven that plane parallel shear flows are unconditionally nonlinearly exponentially stable for tilted streamwise perturbation when the Reynolds number is below a certain critical value and the boundary conditions are either rigid or stress-free.In the case of stress-free boundaries,by taking advantage of the poloidal-toroidal decomposition of a solenoidal field to define energy functionals,it can be even shown that plane parallel shear flows are unconditionally nonlinearly exponentially stable for all Reynolds numbers,where the tilted perturbation can be either spanwise or streamwise.展开更多
Optical glass is the most widely used optical material.It is necessary to measure its geometric characteristic quickly and reliably to meet the quality of optical glass.A vision measuring system combining photoelectri...Optical glass is the most widely used optical material.It is necessary to measure its geometric characteristic quickly and reliably to meet the quality of optical glass.A vision measuring system combining photoelectric autocollimation system with high-precision rotary stage is designed to measure the parallelismand angle of optical glass plane.A novel method is proposed to overcome the difficulty ofmeasuring parallelismof optical glass.The model of parallelism and angle measurement is established and the feasibility is analyzed.The image processing algorithm combining Steger algorithm with the least square method is selected.The uncertainty of angle measurement system for angle measurement is 3.0″.The system can solve the problem of measuring the angle of optical glass with high precision and has important significance for optical system.展开更多
This paper deals with the teaching method in reading engineering drawing. It introduces the basic theory and fundamental ideas as well as the approach of reading views by analyzing lines and planes. It gives out the s...This paper deals with the teaching method in reading engineering drawing. It introduces the basic theory and fundamental ideas as well as the approach of reading views by analyzing lines and planes. It gives out the steps for completing the third view based on the other two views. As it is easy and quick for students to read and understand views by this method, it is welcome by students in teaching practice.展开更多
Pathfinding is a kind of problem widely used in daily life. It is widely used in network games, map navigation and other fields. However, the traditional A* algorithm has some shortcomings, such as heuristic function ...Pathfinding is a kind of problem widely used in daily life. It is widely used in network games, map navigation and other fields. However, the traditional A* algorithm has some shortcomings, such as heuristic function needs to be designed according to different problems, path has many inflection points, and algorithm stability is poor. B* algorithm also has the shortcoming of inaccurate pathfinding. In order to solve the problems existing in A* and B* algorithms, obstacle avoidance regeneration mechanism, pre-exploration mechanism and equivalent waiting strategy are proposed. It adds a bidirectional parallel search mechanism to form an IBP-B* algorithm (Intelligent bi-directional parallel B* routing algorithm). The simulation results show that the speed of IBP-B* algorithm is 182% higher than that of A* algorithm and 366% higher than that of BFS algorithm. Meanwhile, compared with B* algorithm, IBP-B* algorithm improves the pathfinding accuracy of the algorithm.展开更多
网络虚拟化允许多个虚拟网络在同一物理基础设施上共存,有利于未来网络技术的增量部署。然而,当前可编程数据平面提供独占的数据平面抽象难以同时支持多个网络功能,该文提出一种支持并行流水线的虚拟化可编程数据平面结构(Virtualized P...网络虚拟化允许多个虚拟网络在同一物理基础设施上共存,有利于未来网络技术的增量部署。然而,当前可编程数据平面提供独占的数据平面抽象难以同时支持多个网络功能,该文提出一种支持并行流水线的虚拟化可编程数据平面结构(Virtualized P4-based Programmable Data Plane architecture with Parallel Pipeline,VirtP6),允许在单个物理设备上运行多个相互隔离的网络功能。VirtP6改变了可编程数据平面的单一流水线结构,引入并行的多个数据包处理流水线,实现了可编程数据平面的虚拟化,并保证了不同虚拟网络功能之间的资源隔离、流量隔离和访问隔离。最后,针对VirtP6的虚拟化开销、隔离性、可扩展性、网络适用性能进行实验评估。实验结果显示,与HyperP4相比,VirtP6大大降低了虚拟化开销,将延迟减少了68%,吞吐量提高了75%,具有良好的隔离性和扩展性。展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Nos.20274040,20574052)the Program for New Century Excellent Talents in Universities(No.NCET-05-0538)+1 种基金the Natural Science Foundation of Zhejiang Province(Nos.R404047,Y405011,Y405553)China Postdoctoral Science Foundation(No.20060401064).
文摘We use the pruned-enriched Rosenbluth method to investigate systematically the segment density profiles of compact polymer chains confined between two parallel plane walls. The non-adsorption case of adsorption interaction energy ε = 0 and the weak adsorption case of ε= -1 are considered for the compact polymer chains with different chain lengths N and different separation distances between two walls D. Several special entropy effects on the confined compact polymer chains, such as a damped oscillation in the segment density profile for the large separation distance D, are observed and discussed for different separation distances D in the non-adsorption case. In the weak adsorption case, investigations on the segment density profiles indicate that the competition between the entropy and adsorption effects results in an obvious depletion layer. Moreover, the scaling laws of the damped oscillation period Td and the depletion layer width Ld are obtained for the confined compact chains. Most of these results are obtained for the first time so far as we know, which are expected to understand the properties of the confined compact polymer chains more completely.
基金supported by the National Natural Science Foundation of China(21627813)。
文摘The nonlinear stability of plane parallel shear flows with respect to tilted perturbations is studied by energy methods.Tilted perturbation refers to the fact that perturbations form an angleθ∈(0,π/2)with the direction of the basic flows.By defining an energy functional,it is proven that plane parallel shear flows are unconditionally nonlinearly exponentially stable for tilted streamwise perturbation when the Reynolds number is below a certain critical value and the boundary conditions are either rigid or stress-free.In the case of stress-free boundaries,by taking advantage of the poloidal-toroidal decomposition of a solenoidal field to define energy functionals,it can be even shown that plane parallel shear flows are unconditionally nonlinearly exponentially stable for all Reynolds numbers,where the tilted perturbation can be either spanwise or streamwise.
基金supported in part by the National Natural Science Foundation of China under Grant 51805367part by the Natural Science Foundation of Tianjin under Grant 17JCTPJC54200 and Grant 18JCQNJC04800
文摘Optical glass is the most widely used optical material.It is necessary to measure its geometric characteristic quickly and reliably to meet the quality of optical glass.A vision measuring system combining photoelectric autocollimation system with high-precision rotary stage is designed to measure the parallelismand angle of optical glass plane.A novel method is proposed to overcome the difficulty ofmeasuring parallelismof optical glass.The model of parallelism and angle measurement is established and the feasibility is analyzed.The image processing algorithm combining Steger algorithm with the least square method is selected.The uncertainty of angle measurement system for angle measurement is 3.0″.The system can solve the problem of measuring the angle of optical glass with high precision and has important significance for optical system.
基金Supported by Chongqing University’s Book Construction Fund (No. 200515).
文摘This paper deals with the teaching method in reading engineering drawing. It introduces the basic theory and fundamental ideas as well as the approach of reading views by analyzing lines and planes. It gives out the steps for completing the third view based on the other two views. As it is easy and quick for students to read and understand views by this method, it is welcome by students in teaching practice.
文摘Pathfinding is a kind of problem widely used in daily life. It is widely used in network games, map navigation and other fields. However, the traditional A* algorithm has some shortcomings, such as heuristic function needs to be designed according to different problems, path has many inflection points, and algorithm stability is poor. B* algorithm also has the shortcoming of inaccurate pathfinding. In order to solve the problems existing in A* and B* algorithms, obstacle avoidance regeneration mechanism, pre-exploration mechanism and equivalent waiting strategy are proposed. It adds a bidirectional parallel search mechanism to form an IBP-B* algorithm (Intelligent bi-directional parallel B* routing algorithm). The simulation results show that the speed of IBP-B* algorithm is 182% higher than that of A* algorithm and 366% higher than that of BFS algorithm. Meanwhile, compared with B* algorithm, IBP-B* algorithm improves the pathfinding accuracy of the algorithm.
文摘网络虚拟化允许多个虚拟网络在同一物理基础设施上共存,有利于未来网络技术的增量部署。然而,当前可编程数据平面提供独占的数据平面抽象难以同时支持多个网络功能,该文提出一种支持并行流水线的虚拟化可编程数据平面结构(Virtualized P4-based Programmable Data Plane architecture with Parallel Pipeline,VirtP6),允许在单个物理设备上运行多个相互隔离的网络功能。VirtP6改变了可编程数据平面的单一流水线结构,引入并行的多个数据包处理流水线,实现了可编程数据平面的虚拟化,并保证了不同虚拟网络功能之间的资源隔离、流量隔离和访问隔离。最后,针对VirtP6的虚拟化开销、隔离性、可扩展性、网络适用性能进行实验评估。实验结果显示,与HyperP4相比,VirtP6大大降低了虚拟化开销,将延迟减少了68%,吞吐量提高了75%,具有良好的隔离性和扩展性。
