Internet of Things (IoT) as an important and ubiquitous service paradigm is one of the most important issues in IoT applications to provide terminal users with effective and efficient services based on service communi...Internet of Things (IoT) as an important and ubiquitous service paradigm is one of the most important issues in IoT applications to provide terminal users with effective and efficient services based on service community. This paper presents a semantic-based similarity algorithm to build the IoT service community. Firstly, the algorithm reflects that the nodes of IoT contain a wealth of semantic information and makes them to build into the concept tree. Then tap the similarity of the semantic information based on the concept tree. Finally, we achieve the optimization of the service community through greedy algorithm and control the size of the service community by adjusting the threshold. Simulation results show the effectiveness and feasibility of this algorithm.展开更多
Since the resin-based composite materials are of essential importance in many key engineering fields,the manufacture processes are highly worth studying and optimizing for satisfying quality control at the highest pos...Since the resin-based composite materials are of essential importance in many key engineering fields,the manufacture processes are highly worth studying and optimizing for satisfying quality control at the highest possible production rate.In this paper,combined with the impregnation theory,the flow-thermal-mechanical multiphysics coupling model is built to characterize,investigate and optimize the osmotic flow process of hot-melt resin in fiber fabrics with the uniformity and adequacy of resin impregnation as the evaluation criteria.First,the osmotic flow process is characterized by the osmotic flow front of resin,which is tracked by the phase-field method.Then,the influencing factors of roller clearance,temperature and speed are comprehensively investigated.After that,the simulation data of resin impregnation degree are fitted by polynomial curves,with accuracy up to 96.13%,for further investigation of interaction between influencing factors.Finally,based on the above results,the operation parameter combination for impregnation process is optimized with the response surface method and provided as the guidance for practical application.展开更多
Cavity-based flameholder is expected to be applied for ramjets or afterburners,which could work efficiently in the high-altitude space with low pressure.The detailed fluid structure helps to understand the flame stabi...Cavity-based flameholder is expected to be applied for ramjets or afterburners,which could work efficiently in the high-altitude space with low pressure.The detailed fluid structure helps to understand the flame stability principle of the flameholder.The fluid structure in the center section and side section of the cavity-based flameholder is experimentally measured at the inlet pressure of 0.04–0.10 MPa,Mach number of 0.1,and temperature of 300 K.Results indicate that the inlet pressure has a significant effect on the fluid-structure in the cavity.The bluff body affects the generation of the vortex in the cavity.As the inlet pressure decreases from 0.10 MPa to 0.04 MPa,the classical dual-vortex maintains excellent stability in the side section of the cavity.Whereas the single-vortex in the center section gradually becomes incomplete with the inlet pressure varying from 0.10 MPa to 0.06 MPa,and it disappears at 0.04 MPa.The reason is that with the reduction of inlet pressure,the density decreases as well,and the proportion of the mass flow rate attracted to the low-pressure area downstream of the bluff body increases,which leads to the vortex being gradually pulled and destroyed.展开更多
The flame stability limit and propagation characteristics of a reverse-flow combustor without any flame-stabilized device were experimentally investigated under room temperature and pressure.The results indicate that ...The flame stability limit and propagation characteristics of a reverse-flow combustor without any flame-stabilized device were experimentally investigated under room temperature and pressure.The results indicate that it is feasible to stabilize the flame in the recirculation zones constructed by the impact jet flow from the primary holes and dilution holes.The flame projected area is mainly distributed in the recirculation zone upstream of the primary holes,whose presence and absence mark the ignition and extinction.During the ignition process,the growth rate and value of the flame projected area first increase and then decrease with the inlet velocity increasing from 9.4 m/s to 42.1 m/s.A rapid reduction followed by a slow reduction of ignition and lean blowout equivalence ratios is achieved by the increased inlet velocity.Then the non-reacting fluid structure in three sections was measured,and detailed velocity profiles were analyzed to improve the understanding of the flame stabilization mechanism.The results are conducive to the design of an ultra-compact combustor.展开更多
基金Supported by the China Postdoctoral Science Foundation(No. 20100480701)the Ministry of Education of Humanities and Social Sciences Youth Fund Project(11YJC880119)
文摘Internet of Things (IoT) as an important and ubiquitous service paradigm is one of the most important issues in IoT applications to provide terminal users with effective and efficient services based on service community. This paper presents a semantic-based similarity algorithm to build the IoT service community. Firstly, the algorithm reflects that the nodes of IoT contain a wealth of semantic information and makes them to build into the concept tree. Then tap the similarity of the semantic information based on the concept tree. Finally, we achieve the optimization of the service community through greedy algorithm and control the size of the service community by adjusting the threshold. Simulation results show the effectiveness and feasibility of this algorithm.
基金financially supported by the National Natural Science Foundation of China(52176202)。
文摘Since the resin-based composite materials are of essential importance in many key engineering fields,the manufacture processes are highly worth studying and optimizing for satisfying quality control at the highest possible production rate.In this paper,combined with the impregnation theory,the flow-thermal-mechanical multiphysics coupling model is built to characterize,investigate and optimize the osmotic flow process of hot-melt resin in fiber fabrics with the uniformity and adequacy of resin impregnation as the evaluation criteria.First,the osmotic flow process is characterized by the osmotic flow front of resin,which is tracked by the phase-field method.Then,the influencing factors of roller clearance,temperature and speed are comprehensively investigated.After that,the simulation data of resin impregnation degree are fitted by polynomial curves,with accuracy up to 96.13%,for further investigation of interaction between influencing factors.Finally,based on the above results,the operation parameter combination for impregnation process is optimized with the response surface method and provided as the guidance for practical application.
基金supported by the National Science and Technology Major Project(No.2017-III-0008-0034)。
文摘Cavity-based flameholder is expected to be applied for ramjets or afterburners,which could work efficiently in the high-altitude space with low pressure.The detailed fluid structure helps to understand the flame stability principle of the flameholder.The fluid structure in the center section and side section of the cavity-based flameholder is experimentally measured at the inlet pressure of 0.04–0.10 MPa,Mach number of 0.1,and temperature of 300 K.Results indicate that the inlet pressure has a significant effect on the fluid-structure in the cavity.The bluff body affects the generation of the vortex in the cavity.As the inlet pressure decreases from 0.10 MPa to 0.04 MPa,the classical dual-vortex maintains excellent stability in the side section of the cavity.Whereas the single-vortex in the center section gradually becomes incomplete with the inlet pressure varying from 0.10 MPa to 0.06 MPa,and it disappears at 0.04 MPa.The reason is that with the reduction of inlet pressure,the density decreases as well,and the proportion of the mass flow rate attracted to the low-pressure area downstream of the bluff body increases,which leads to the vortex being gradually pulled and destroyed.
基金supported by the National Nature Science Foundation of China through Grant No.51506086the Jiangsu Funding Program for Excellent Postdoctoral Talent(No.316958)+3 种基金the Natural Science Foundation of Jiangsu Province,China(BK20230932)the China Postdoctoral Science Foundation(No.2023M741697)the Fundamental Research Funds for the Central Universities(No.30923010306)the financial support from Low-carbon Aerospace Power Engineering Research Center of Ministry of Education(CEPE2020018)。
文摘The flame stability limit and propagation characteristics of a reverse-flow combustor without any flame-stabilized device were experimentally investigated under room temperature and pressure.The results indicate that it is feasible to stabilize the flame in the recirculation zones constructed by the impact jet flow from the primary holes and dilution holes.The flame projected area is mainly distributed in the recirculation zone upstream of the primary holes,whose presence and absence mark the ignition and extinction.During the ignition process,the growth rate and value of the flame projected area first increase and then decrease with the inlet velocity increasing from 9.4 m/s to 42.1 m/s.A rapid reduction followed by a slow reduction of ignition and lean blowout equivalence ratios is achieved by the increased inlet velocity.Then the non-reacting fluid structure in three sections was measured,and detailed velocity profiles were analyzed to improve the understanding of the flame stabilization mechanism.The results are conducive to the design of an ultra-compact combustor.
