Aiming to efficiently support theLocator/Identifier Separation Protocol(LISP),in this paper,we present an enhanced pointerbased DHT mapping system:LISP-PCHORD.The system creates a pointer space to build ontop of stand...Aiming to efficiently support theLocator/Identifier Separation Protocol(LISP),in this paper,we present an enhanced pointerbased DHT mapping system:LISP-PCHORD.The system creates a pointer space to build ontop of standard DHTs.Mappings within thepointer space are(Endpoint Identifiers(EID),pointers) where the pointer is the address ofthe root node(the physical node that stores themappings) of the corresponding(EID,RoutingLocators(RLOCs)) mappings.In addition toenabling architectural qualities such as scalability and reliability,the proposed LISP-PCHORDcan copy with flat EIDs such as self-certifyingEIDs.The performance of the mapping systemplays a key role in LISP;however,DHT-basedapproaches for LISP seldom consider the mismatch problem that heavily damages the system performance in terms of lookup latency.In order to mitigate the mismatch problem andachieve optimal performance,we propose anoptimization design method that seeks an optimal matching relationship between P-nodes(nodes within the pointer space) and the physical nodes on the basis of the given lookuptraffic matrix.In order to find the optimal matching relationship,we provide two solutions:a linear programming method and a geneticalgorithm.Finally,we evaluate the performance of the proposed scheme and compare itwith that of LISP-DHT.展开更多
In order to solve the problem of weak power performance of vehicle equipped with continuously variable transmission(CVT) system working under transient operating conditions, a new CVT equipped with planetary gear mech...In order to solve the problem of weak power performance of vehicle equipped with continuously variable transmission(CVT) system working under transient operating conditions, a new CVT equipped with planetary gear mechanism and flywheel was researched, a design method of transmission parameter optimization was proposed, and the comprehensive matching control strategy was established for the new transmission system. Fuzzy controllers for throttle opening and CVT speed ratio were designed, and power performance and fuel economy of both vehicles respectively equipped with conventional CVT system and new transmission system wrere compared and analyzed by simulation. The results show that power performance and fuel economy of the vehicle equipped with new transmission system are better than that equipped with conventional CVT, thus the rationality of the parameter design method and control algorithm are verified.展开更多
The aerodynamic performance, structural strength, and wheel weight are three important factors in the design process of the radial turbine for micro gas turbines. This study presents the experimental validation proces...The aerodynamic performance, structural strength, and wheel weight are three important factors in the design process of the radial turbine for micro gas turbines. This study presents the experimental validation process of this integrated optimization design method by using the similarity theory. Cold modeling tests and investigations into the aerodynamic characteristics were performed. Experimental results showed that the aerodynamic efficiency of the micro radial turbine is 84.3% at the design point while also satisfying the aerodynamic and strength requirements. Meanwhile, the total weight of the turbine wheel is 3.8 kg which has only a 52.8% mass of the original design. This indicates that the radial turbine designed through this technique has a high aerodynamic performance, and thus can be applied to micro gas turbines. The results validated that this integrated optimization design method is reliable.展开更多
This paper presents the performance evaluation of a regenerative pump to increase its efficiency using optimal design method. Two design parameters which define the shape of the pump impeller, are introduced and analy...This paper presents the performance evaluation of a regenerative pump to increase its efficiency using optimal design method. Two design parameters which define the shape of the pump impeller, are introduced and analyzed. Pump performance is evaluated by numerical simulation and design of experiments(DOE). To analyze three-dimensional flow field in the pump, general analysis code, CFX, is used in the present work. Shear stress turbulence model is employed to estimate the eddy viscosity. Experimental apparatus with an open-loop facility is set up for measuring the pump performance. Pump performance, efficiency and pressure, obtained from numerical simulation are validated by comparison with the results of experiments. Throughout the shape optimization of the pump impeller at the operating flow condition, the pump efficiency is successfully increased by 3 percent compared to the reference pump. It is noted that the pressure increase of the optimum pump is mainly caused by higher momentum force generated inside blade passage due to the optimal blade shape. Comparisons of pump internal flow on the reference and optimum pump are also investigated and discussed in detail.展开更多
基金supported by the National Key Basic Research Program of China(973Program) under Grant No.2007CB307100the National Natural Science Foundation of China under Grant No.61001084
文摘Aiming to efficiently support theLocator/Identifier Separation Protocol(LISP),in this paper,we present an enhanced pointerbased DHT mapping system:LISP-PCHORD.The system creates a pointer space to build ontop of standard DHTs.Mappings within thepointer space are(Endpoint Identifiers(EID),pointers) where the pointer is the address ofthe root node(the physical node that stores themappings) of the corresponding(EID,RoutingLocators(RLOCs)) mappings.In addition toenabling architectural qualities such as scalability and reliability,the proposed LISP-PCHORDcan copy with flat EIDs such as self-certifyingEIDs.The performance of the mapping systemplays a key role in LISP;however,DHT-basedapproaches for LISP seldom consider the mismatch problem that heavily damages the system performance in terms of lookup latency.In order to mitigate the mismatch problem andachieve optimal performance,we propose anoptimization design method that seeks an optimal matching relationship between P-nodes(nodes within the pointer space) and the physical nodes on the basis of the given lookuptraffic matrix.In order to find the optimal matching relationship,we provide two solutions:a linear programming method and a geneticalgorithm.Finally,we evaluate the performance of the proposed scheme and compare itwith that of LISP-DHT.
基金Project(2011BA3019)supported by the Chongqing Natural Science Foundation,China
文摘In order to solve the problem of weak power performance of vehicle equipped with continuously variable transmission(CVT) system working under transient operating conditions, a new CVT equipped with planetary gear mechanism and flywheel was researched, a design method of transmission parameter optimization was proposed, and the comprehensive matching control strategy was established for the new transmission system. Fuzzy controllers for throttle opening and CVT speed ratio were designed, and power performance and fuel economy of both vehicles respectively equipped with conventional CVT system and new transmission system wrere compared and analyzed by simulation. The results show that power performance and fuel economy of the vehicle equipped with new transmission system are better than that equipped with conventional CVT, thus the rationality of the parameter design method and control algorithm are verified.
基金the National Natural Science Foundation of China，the China Postdoctoral Science Founda-tion
文摘The aerodynamic performance, structural strength, and wheel weight are three important factors in the design process of the radial turbine for micro gas turbines. This study presents the experimental validation process of this integrated optimization design method by using the similarity theory. Cold modeling tests and investigations into the aerodynamic characteristics were performed. Experimental results showed that the aerodynamic efficiency of the micro radial turbine is 84.3% at the design point while also satisfying the aerodynamic and strength requirements. Meanwhile, the total weight of the turbine wheel is 3.8 kg which has only a 52.8% mass of the original design. This indicates that the radial turbine designed through this technique has a high aerodynamic performance, and thus can be applied to micro gas turbines. The results validated that this integrated optimization design method is reliable.
基金supported by a grant(16AUDPB083704-03)from Architecture&Urban Development Research Program funded by Ministry of Land,Infrastructure and Transport of Korean government
文摘This paper presents the performance evaluation of a regenerative pump to increase its efficiency using optimal design method. Two design parameters which define the shape of the pump impeller, are introduced and analyzed. Pump performance is evaluated by numerical simulation and design of experiments(DOE). To analyze three-dimensional flow field in the pump, general analysis code, CFX, is used in the present work. Shear stress turbulence model is employed to estimate the eddy viscosity. Experimental apparatus with an open-loop facility is set up for measuring the pump performance. Pump performance, efficiency and pressure, obtained from numerical simulation are validated by comparison with the results of experiments. Throughout the shape optimization of the pump impeller at the operating flow condition, the pump efficiency is successfully increased by 3 percent compared to the reference pump. It is noted that the pressure increase of the optimum pump is mainly caused by higher momentum force generated inside blade passage due to the optimal blade shape. Comparisons of pump internal flow on the reference and optimum pump are also investigated and discussed in detail.
