In this work,the deformation of free interface during water entry and exit of a circular cylinder is investigated numerically by using the two-dimensional(2D)immersed boundary-multiphase lattice Boltzmann flux solver(...In this work,the deformation of free interface during water entry and exit of a circular cylinder is investigated numerically by using the two-dimensional(2D)immersed boundary-multiphase lattice Boltzmann flux solver(IB-MLBFS).The fluid domain is discretized by finite volume discretization,and the flux on the grid interface is evaluated by lattice Boltzmann equations.Both the implicit velocity correction and the surface flux correction are implemented by using the immersed boundary-method to consider the fluid-structure interaction and the contact interface between the multiphase fluids and the structure.First,the water entry of a circular cylinder is simulated and the results are compared with the experiment,which considered the length-diameter ratio of the circular cylinder.The reliability of 2D simulation is verified and the deformation of the free interface is well investigated.Afterward,the water exit of a circular cylinder with constant velocity is simulated,which is less researched.In addition,the results show the advantage of present IB-MLBFS to some extent.Finally,the water exit and re-entry of a circular cylinder are presented,and the results present the complex deformation of the free interface and the dynamic response of the moving structure.Based on the numerical results,the free interface of the multiphase fluids is well captured,and the contact interface on the boundary of the moving structure is accurately presented by the IB-MLBFS.展开更多
Modern cars are mostly computerized and equipped with passive keyless entry and start(PKES) system. PKES is based on Radio Frequency Identification(RFID) technology for authentication of the authorized drivers. RFID t...Modern cars are mostly computerized and equipped with passive keyless entry and start(PKES) system. PKES is based on Radio Frequency Identification(RFID) technology for authentication of the authorized drivers. RFID technology has replaced the conventional ways of identification and authorization in order to facilitate users while introducing new security challenges. In this article, we focused on verifying the presence of authorized key in the physical proximity of car by employing multiple antennas. Application of multiple antennas to the currently developed cryptographic algorithms opens a new approach for researchers to improve security of RFID based systems. We propose an advanced security system for PKES using multiple antennas wherein an authorized key passes through multiple vicinities to allow driver to access and start the car. Furthermore, we modified a light-weight cryptographic protocol named as HB(Hopper and Blum) protocol to integrate it with the proposed design based on multiple antennas. Simulation results show improvement in security functionality while keeping in view the efficiency constraints.展开更多
In this paper, we consider a unidirectional highway road with one entry/exit uniformly distributed on the road interval. One road side unit (RSU) is located on the position of the entry/exit. We build an analytical mo...In this paper, we consider a unidirectional highway road with one entry/exit uniformly distributed on the road interval. One road side unit (RSU) is located on the position of the entry/exit. We build an analytical model to study the network connectivity problem. In building the analytical model, we take into account several parameters, such as vehicle arrival rate, vehicle moving speed, vehicle communication radius, RSU communication radius, highway road length and the probability of vehicles driving through the entry/exit. The analytical model is verified by using simulation tools.展开更多
This work investigated multiple jet nozzles with various geometrical shape,number of exits,and material on reducing noise radiated from jet flows.Nozzles are categorized in two groups with few and many exit numbers,ea...This work investigated multiple jet nozzles with various geometrical shape,number of exits,and material on reducing noise radiated from jet flows.Nozzles are categorized in two groups with few and many exit numbers,each with various exit shapes,slot and circular,and geometry.Firstly,nozzles are designed and then fabricated by a 3D printer,Form Labs,Form2USA,with polymeric resin.Also,the nozzle with the most noise reduction made of stainless steel.Noise and air thrust were measured at three air pressure gauges,3,5,7 BAR and directions from nozzle apex,30°,90°,135°.Nozzles with slot exit shape made of both plastic and stainless steel revealed the most noise reduction among all nozzles with few exit numbers,nearly 11–14 dB(A)and 11.5–15 dB(A),respectively.On average,slotted nozzle noise reduction was nearly 5–6 dB(A)more than finned nozzle.However,nozzles with more exit numbers,finned and finned-central exit,illustrated much more noise reduction than nozzles with few exit numbers,by almost 16–18 dB(A),they represented similar sound.All tested nozzles and open pipe demonstrated equal air thrust at each pressure gauges.The nozzles with slotted exit shape,either plastic or stainless steel,can provide reasonable noise reduction in comparison to other configuration with few exit numbers.In contrast,nozzles with more exit numbers demonstrated the most noise reduction.展开更多
Based on extensive micro data sets, this paper examines the relationship among large-scale entry and exit, competition and total factor productivity （TFP） growth of China＇s industry during economic transition and m...Based on extensive micro data sets, this paper examines the relationship among large-scale entry and exit, competition and total factor productivity （TFP） growth of China＇s industry during economic transition and market opening. We have arrived at these findings： market opening spurs entry and exit of large numbers of non-state-owned enterprises （non-SOEs） and facilitates dynamic competition; through the stimulation effect of competition, entry and exit push TFP growth on the part of enterprises; through the resource reallocation effect, entry and exit promote growth of the aggregate TFP. However, results indicate that the resource allocation efficiency remains very low in capital-intensive industries where the government intervenes a lot. To conclude, promoting open competition is significant to the growth of industrial sectors ＇productivity.展开更多
For ordinary tourists, simpler entry and exit procedures and a broader range of duty-free goods in Hainan create a better travel and shopping experience.For China’s earnest endeavor to deepen reform and opening-up, i...For ordinary tourists, simpler entry and exit procedures and a broader range of duty-free goods in Hainan create a better travel and shopping experience.For China’s earnest endeavor to deepen reform and opening-up, implementation of the special customs operations policy in Hainan represents a significant step forward. For businesses in Malaysia and other ASEAN member states, especially export-oriented small and medium-sized enterprises (SMEs), Hainan serves as a“transit hub” for accessing the Chinese market and even other Asian markets.展开更多
基金Supported by the National Natural Science Foundation of China(52061135107)the Fundamental Research Fund for the Central Universities(DUT20TD108,DUT20LAB308)the Liao Ning Revitalization Talents Program(XLYC1908027),and Dalian Innovation Research Team in Key Areas(2020RT03).
文摘In this work,the deformation of free interface during water entry and exit of a circular cylinder is investigated numerically by using the two-dimensional(2D)immersed boundary-multiphase lattice Boltzmann flux solver(IB-MLBFS).The fluid domain is discretized by finite volume discretization,and the flux on the grid interface is evaluated by lattice Boltzmann equations.Both the implicit velocity correction and the surface flux correction are implemented by using the immersed boundary-method to consider the fluid-structure interaction and the contact interface between the multiphase fluids and the structure.First,the water entry of a circular cylinder is simulated and the results are compared with the experiment,which considered the length-diameter ratio of the circular cylinder.The reliability of 2D simulation is verified and the deformation of the free interface is well investigated.Afterward,the water exit of a circular cylinder with constant velocity is simulated,which is less researched.In addition,the results show the advantage of present IB-MLBFS to some extent.Finally,the water exit and re-entry of a circular cylinder are presented,and the results present the complex deformation of the free interface and the dynamic response of the moving structure.Based on the numerical results,the free interface of the multiphase fluids is well captured,and the contact interface on the boundary of the moving structure is accurately presented by the IB-MLBFS.
基金supported by the National Key Research and Development Program(No.2016YFB0800602)National Natural Science Foundation of China(NSFC)(No.61502048)Shandong provincial Key Research and Development Program of China(2018CXGC0701,2018GGX106005)
文摘Modern cars are mostly computerized and equipped with passive keyless entry and start(PKES) system. PKES is based on Radio Frequency Identification(RFID) technology for authentication of the authorized drivers. RFID technology has replaced the conventional ways of identification and authorization in order to facilitate users while introducing new security challenges. In this article, we focused on verifying the presence of authorized key in the physical proximity of car by employing multiple antennas. Application of multiple antennas to the currently developed cryptographic algorithms opens a new approach for researchers to improve security of RFID based systems. We propose an advanced security system for PKES using multiple antennas wherein an authorized key passes through multiple vicinities to allow driver to access and start the car. Furthermore, we modified a light-weight cryptographic protocol named as HB(Hopper and Blum) protocol to integrate it with the proposed design based on multiple antennas. Simulation results show improvement in security functionality while keeping in view the efficiency constraints.
文摘In this paper, we consider a unidirectional highway road with one entry/exit uniformly distributed on the road interval. One road side unit (RSU) is located on the position of the entry/exit. We build an analytical model to study the network connectivity problem. In building the analytical model, we take into account several parameters, such as vehicle arrival rate, vehicle moving speed, vehicle communication radius, RSU communication radius, highway road length and the probability of vehicles driving through the entry/exit. The analytical model is verified by using simulation tools.
文摘This work investigated multiple jet nozzles with various geometrical shape,number of exits,and material on reducing noise radiated from jet flows.Nozzles are categorized in two groups with few and many exit numbers,each with various exit shapes,slot and circular,and geometry.Firstly,nozzles are designed and then fabricated by a 3D printer,Form Labs,Form2USA,with polymeric resin.Also,the nozzle with the most noise reduction made of stainless steel.Noise and air thrust were measured at three air pressure gauges,3,5,7 BAR and directions from nozzle apex,30°,90°,135°.Nozzles with slot exit shape made of both plastic and stainless steel revealed the most noise reduction among all nozzles with few exit numbers,nearly 11–14 dB(A)and 11.5–15 dB(A),respectively.On average,slotted nozzle noise reduction was nearly 5–6 dB(A)more than finned nozzle.However,nozzles with more exit numbers,finned and finned-central exit,illustrated much more noise reduction than nozzles with few exit numbers,by almost 16–18 dB(A),they represented similar sound.All tested nozzles and open pipe demonstrated equal air thrust at each pressure gauges.The nozzles with slotted exit shape,either plastic or stainless steel,can provide reasonable noise reduction in comparison to other configuration with few exit numbers.In contrast,nozzles with more exit numbers demonstrated the most noise reduction.
文摘Based on extensive micro data sets, this paper examines the relationship among large-scale entry and exit, competition and total factor productivity （TFP） growth of China＇s industry during economic transition and market opening. We have arrived at these findings： market opening spurs entry and exit of large numbers of non-state-owned enterprises （non-SOEs） and facilitates dynamic competition; through the stimulation effect of competition, entry and exit push TFP growth on the part of enterprises; through the resource reallocation effect, entry and exit promote growth of the aggregate TFP. However, results indicate that the resource allocation efficiency remains very low in capital-intensive industries where the government intervenes a lot. To conclude, promoting open competition is significant to the growth of industrial sectors ＇productivity.
文摘For ordinary tourists, simpler entry and exit procedures and a broader range of duty-free goods in Hainan create a better travel and shopping experience.For China’s earnest endeavor to deepen reform and opening-up, implementation of the special customs operations policy in Hainan represents a significant step forward. For businesses in Malaysia and other ASEAN member states, especially export-oriented small and medium-sized enterprises (SMEs), Hainan serves as a“transit hub” for accessing the Chinese market and even other Asian markets.
