A series of experiments were conducted for Al-1.65%Si (mass fraction) alloy melt to study the formation of grain refining structure with ultrasonic stirring. The cooling curves of ingots with ultrasonic were measured ...A series of experiments were conducted for Al-1.65%Si (mass fraction) alloy melt to study the formation of grain refining structure with ultrasonic stirring. The cooling curves of ingots with ultrasonic were measured and compared with those without ultrasonic. At the same time, the effect of the time of ultrasonic stirring on solidification structure of ingots was investigated. The influence of ultrasonic on the grain-refining efficiency of ingots was analyzed. In order to well understand the melts behavior under ultrasonic, by using ammonium chloride solution, the simulation experiment was carried out and the temperature distribution in ingot with or without ultrasonic was compared. The results indicate that the ultrasonic reduces the temperature inhomogeneity of melt, i.e. the ultrasonic helps to homogenize the melt temperature. The effect of stirring and heat generation in ingot start to occur with increasing the time of ultrasonic stirring.展开更多
The effects of partial substitution of La by Ce and Ni by Al, Fe, or Co in LaNi_5-based alloys on hydrogen storage performance were systematically studied. All samples were prepared using vacuum arc melting in an argo...The effects of partial substitution of La by Ce and Ni by Al, Fe, or Co in LaNi_5-based alloys on hydrogen storage performance were systematically studied. All samples were prepared using vacuum arc melting in an argon atmosphere. The results showed that for LaNi_(5-x)M_x(M = Al, Fe, or Co) alloys, the lattice constants and unit cell volumes increased with an increasing amount of Al and Fe. On the other hand, these parameters decreased upon partial substitution of La by Ce. In addition, the lattice constant remained almost constant in the La_(0.6)Ce_(0.4)Ni_(5–x)Cox alloys regardless of the value of x(x = 0.3, 0.6, or 0.9), as Ce might enhance the homogeneity of the CaCu_5-type phase in Co-containing alloys. The hydrogen storage properties of the alloys were investigated using pressure, composition, and temperature isotherms. The experimental results showed that the plateau pressure decreased with an increasing content of Al, Fe, or Co, but it increased with Ce addition. Furthermore, the plateau pressures of all Co-containing alloys were almost identical upon substitution with Ce. Finally, the enthalpy(ΔH) and entropy(ΔS) values for all alloys were calculated using van't Hoff plots. The relationship between the lattice parameters and enthalpy changes for hydrogenation will be discussed.展开更多
Removal experiments of phenol, aniline, 2,4-dichlorophenol, nonylphenol and bisphenol A (BPA) using Spirodela polyrrhiza- bacterial associations revealed that all compounds but BPA underwent accelerated removal. The...Removal experiments of phenol, aniline, 2,4-dichlorophenol, nonylphenol and bisphenol A (BPA) using Spirodela polyrrhiza- bacterial associations revealed that all compounds but BPA underwent accelerated removal. The mechanisms differed depending on the substrates. It was found that S. polyrrhiza has a great ability to release phenolic compound-rich root exudates, and the exudates seem to stimulate bacterial degradation of a variety of aromatic compounds.展开更多
The tungsten-inert-gas (TIG) arc welding experiments of cemented carbide YG30 and steel 45 were carried out using the Ni-Fe-C filling alloys. The eta phases and mechanical properties of welded joints were analyzed by ...The tungsten-inert-gas (TIG) arc welding experiments of cemented carbide YG30 and steel 45 were carried out using the Ni-Fe-C filling alloys. The eta phases and mechanical properties of welded joints were analyzed by means of scanning electronic microscope (SEM), transmission electronic microscope (TEM) coupled with selected diffraction, electronic probe microanalysis and bending strength methods. The experimental results show that the chemical composition of the filling alloys affects eta phase formation. When the carbon and nickel contents in filling alloys are 0.61 wt% and 55.29 wt%, respectively, no eta phases form. And the joint bending strength is the highest to 1.352 GPa. But if they are 0.01wt% and 55.38wt%, the eta phases are formed at the boundaries of the cemented carbide and the weld, and the thickness of eta phase layer is about 110 micrometers. And the joint bending strength is low. Usually, these eta phases are anomalously granular, and easy to accumulate at the boundaries between cemented carbides and the weld. They are multiple M_6C rich in tungsten and iron.展开更多
Objective:To evaluate the neuroprotective effects of the organic components of scallop shells(scallop shell extract) on memory impairment and locomotor activity induced by scopolamine or 5-methyl-10,11-dihydro-5H-dibe...Objective:To evaluate the neuroprotective effects of the organic components of scallop shells(scallop shell extract) on memory impairment and locomotor activity induced by scopolamine or 5-methyl-10,11-dihydro-5H-dibenzo(a,d) cyclohepten-5,10-imine(MK801).Methods:Effect of the scallop shell extract on memory impairment and locomotor activity was investigated using the Y-maze test,the Morris water maze test,and the open field test.Results:Scallop shell extract significantly reduced scopolamine-induced short-term memory impairment and partially reduced scopolamine-induced spatial memory impairment in the Morris water maze test.Scallop shell extract suppressed scopolamine-induced elevation of acetylcholine esterase activity in the cerebral cortex.Treatment with scallop shell extract reversed the increase in locomotor activity induced by scopolamine.Scallop shell extract also suppressed the increase in locomotor activity induced by MK801.Conclusions:Our results provide initial evidence that scallop shell extract reduces scopolamine-induced memory impairment and suppresses MK-801-induced hyperlocomotion.展开更多
Initially as an extension of cloud computing, fog computing has been inspiring new ideas about moving computing tasks to the edge of networks. In fog, we often repeat the procedure of placing services because of the g...Initially as an extension of cloud computing, fog computing has been inspiring new ideas about moving computing tasks to the edge of networks. In fog, we often repeat the procedure of placing services because of the geographical distribution of mobile users. We may not expect a fixed demand and supply relationship between users and service providers since users always prefer nearby service with less time delay and transmission consumption. That is, a plug-and-play service mode is what we need in fog. In this paper, we put forward a dynamic placement strategy for fog service to guarantee the normal service provision and optimize the Quality of Service (QoS). The simulation results show that our strategy can achieve better performance under metrics including energy consumption and end-to-end latency. Moreover, we design a real Plug-and-Play Fog (PnPF) based on Raspberry Pi and OpenWrt to provide fog services for wireless multimedia networks.展开更多
To study the effect of impingement surface geometry, a cavitation erosion experiment was conducted using a submerged cavitating jet rig with hydraulic oil. The test setup comprised a test chamber with a long-orifice n...To study the effect of impingement surface geometry, a cavitation erosion experiment was conducted using a submerged cavitating jet rig with hydraulic oil. The test setup comprised a test chamber with a long-orifice nozzle, a hydraulic pump with an electric motor, hydraulic auxiliaries, including valves, a cooler, a filter, a reservoir, and measuring instruments, including pressure gages and a thermometer. Hexahedral specimens made of aluminum alloy with flat and grooved surfaces and oblique angles were prepared. Hydraulic oil with a viscosity grade of 32 was used at 40°C as the test fluid. The upstream absolute pressure was kept at 10.1 MPa and the cavitation numbers were set at 0.02 - 0.04. The results of this experiment yielded the following conclusions. The mass loss of the grooved specimens did not increase monotonically as the exposure time increased. The standoff distances at the maximum mass loss for the flat and grooved specimens were almost equivalent. The mass loss decreased as the oblique angle increased and the cavitation number increased, regardless of the presence of grooves. The surfaces were eroded in a ring-like region, but the region elongated as the angle increased. For the grooved specimens, the ridges on the ring were eroded, and when the directions of the grooves and the flow matched, the roots and flanks were severely eroded.展开更多
The objective of this investigation is to study the influence of vanadium(5.0wt%–10.0wt%) and chromium(0–9.0wt%) on the microstructure and hardness of Cr-V-Mn-Ni white cast irons with spheroidal vanadium carbide...The objective of this investigation is to study the influence of vanadium(5.0wt%–10.0wt%) and chromium(0–9.0wt%) on the microstructure and hardness of Cr-V-Mn-Ni white cast irons with spheroidal vanadium carbides. The alloys' microstructural features are presented and discussed with regard to the distribution of phase elements. The structural constituents of the alloys are spheroidal VC, proeutectoid cementite, ledeburite eutectic, rosette-shaped carbide eutectic(based on M7C3), pearlite, martensite, and austenite. Their combinations and area fraction(AF) ratios are reported to be influenced by the alloys' chemical composition. Spheroidized VC particles are found to be sites for the nucleation of carbide eutectics. Cr and V are shown to substitute each other in the VC and M7C3 carbides, respectively. Chromium alloying leads to the formation of a eutectic(γ-Fe + М7С3), preventing the appearance of proeutectoid cementite in the structure. Vanadium and chromium are revealed to increase the total carbide fraction and the amount of austenite in the matrix. Cr is observed to play a key role in controlling the metallic matrix microstructure.展开更多
Full factorial design was used to evaluate the two-body abrasive resistance of 3wt%C–4wt%Mn–1.5wt%Ni spheroidal carbide cast irons with varying vanadium(5.0wt%–10.0wt%) and chromium(up to 9.0wt%) contents. The ...Full factorial design was used to evaluate the two-body abrasive resistance of 3wt%C–4wt%Mn–1.5wt%Ni spheroidal carbide cast irons with varying vanadium(5.0wt%–10.0wt%) and chromium(up to 9.0wt%) contents. The alloys were quenched at 920℃. The regression equation of wear rate as a function of V and Cr contents was proposed. This regression equation shows that the wear rate decreases with increasing V content because of the growth of spheroidal VC carbide amount. Cr influences the overall response in a complex manner both by reducing the wear rate owing to eutectic carbides(M7C3) and by increasing the wear rate though stabilizing austenite to deformation-induced martensite transformation. This transformation is recognized as an important factor in increasing the abrasive response of the alloys. By analyzing the regression equation, the optimal content ranges are found to be 7.5wt%–10.0wt% for V and 2.5wt%–4.5wt% for Cr, which corresponds to the alloys containing 9vol%–15vol% spheroidal VC carbides, 8vol%–16vol% M7C3, and a metastable austenite/martensite matrix. The wear resistance is 1.9–2.3 times that of the traditional 12wt% V–13wt% Mn spheroidal carbide cast iron.展开更多
We perform the extended x-ray absorption tlne structure (EXAFS) measurement to investigate the local structure of amorphous alloys CexRu100-x (x = 9, 43 and 80). The interatomic distances of the nearest Ru-Ce and ...We perform the extended x-ray absorption tlne structure (EXAFS) measurement to investigate the local structure of amorphous alloys CexRu100-x (x = 9, 43 and 80). The interatomic distances of the nearest Ru-Ce and Ru-Ru pairs derived from EXAFS are fully independent of Ce concentration. On the other hand the distance between neighboring Ce atoms increases sharply with the Ce content, which is exactly proportional to the Ce effective magnetic moment. We discuss the relation between the atomic distance and the effective magnetic moment from the point of view of the magneto-volume effect.展开更多
Internet of Medical Things(IoMT)plays an essential role in collecting and managing personal medical data.In recent years,blockchain technology has put power in traditional IoMT systems for data sharing between differe...Internet of Medical Things(IoMT)plays an essential role in collecting and managing personal medical data.In recent years,blockchain technology has put power in traditional IoMT systems for data sharing between different medical institutions and improved the utilization of medical data.However,some problems in the information transfer process between wireless medical devices and mobile medical apps,such as information leakage and privacy disclosure.This paper first designs a cross-device key agreement model for blockchain-enabled IoMT.This model can establish a key agreement mechanism for secure medical data sharing.Meanwhile,a certificateless authenticated key agreement(KA)protocol has been proposed to strengthen the information transfer security in the cross-device key agreement model.The proposed KA protocol only requires one exchange of messages between the two parties,which can improve the protocol execution efficiency.Then,any unauthorized tampering of the transmitted signed message sent by the sender can be detected by the receiver,so this can guarantee the success of the establishment of a session key between the strange entities.The blockchain ledger can ensure that the medical data cannot be tampered with,and the certificateless mechanism can weaken the key escrow problem.Moreover,the security proof and performance analysis are given,which show that the proposed model and KA protocol are more secure and efficient than other schemes in similar literature.展开更多
Extracting approximate symmetry planes is a challenge due to the difficulty of accurately measuring numerical values. Introducing the approximate symmetry planes of a 3D point set, this paper presents a new method by ...Extracting approximate symmetry planes is a challenge due to the difficulty of accurately measuring numerical values. Introducing the approximate symmetry planes of a 3D point set, this paper presents a new method by gathering normal vectors of potential of the planes, clustering the high probability ones, and then testing and verifying the planes. An experiment showed that the method is effective, robust and universal for extracting the complete approximate planes of symmetry of a random 3D point set.展开更多
Through experimental analysis of the liquid flows in a flow channel instrument, prompt evaluation of the physically defined viscosity of non-Newtonian liquid foods was investigated for development into a structurally ...Through experimental analysis of the liquid flows in a flow channel instrument, prompt evaluation of the physically defined viscosity of non-Newtonian liquid foods was investigated for development into a structurally simple and easy-to-use viscometer. For Newtonian and non-Newtonian test liquids, a relation between the friction coefficient and Reynolds number, which was dimensionless as derived from an expression of analysis as a gravity current, indicated a condition under which the flow in the instrument was laminar and under which an average shear rate was on the order of less than 1 s~. Prediction organized based on this empirical relation reproduced practically the flow curve determined for the liquid foods using a rotor type viscometer. Utilization of the channel instrument as a viscometer was formulated in terms of physical meanings of measurements such as the flow length and elapsed time.展开更多
Consequent-pole permanent magnet synchronous machines(CP-PMSMs)have attracted considerable interest as a means of reducing manufacturing costs through a marked reduction in the volume of permanent magnet required to m...Consequent-pole permanent magnet synchronous machines(CP-PMSMs)have attracted considerable interest as a means of reducing manufacturing costs through a marked reduction in the volume of permanent magnet required to meet a particular torque specification.In this paper,novel rotor topologies for a CP-PMSM are derived to unlock the full design space potential.The ON/OFF method is introduced to manage the laminated steel material distribution over the rotor region,high average torque and low torque ripple are the objects of rotor design,and the immune algorithm is used to search for the optimal material distribution for the formulated problem.More than 9000 different rotor topologies are created and evaluated within 12 hours by this methodology.The optimal topologies under different design strategy are presented,and performance of these topologies are analyzed.The analysis results show that the proposed methodology can deliver novel rotor topologies for the CP-PMSM with surprising torque quality since the torque ripple is suppressed to a low level with no average torque sacrifice.展开更多
The nano-infiltration and transient eutectic-phase (NITE) method is one of the most attractive methods for fabrication of SiC and SiC/SiC composites. In the NITE method, preform densification is essential option for d...The nano-infiltration and transient eutectic-phase (NITE) method is one of the most attractive methods for fabrication of SiC and SiC/SiC composites. In the NITE method, preform densification is essential option for damage less near-net shaping technique. However, optimization of preform densification is insufficient yet. The objective of this study is to evaluate the effects of pressure during preform densification on SiC/SiC composites. The preform before preform densification has many pores in the inter-prepreg sheets. These pores were disappeared by preform densification. As the effects of pressure on preform, densification in the intra-fiber-bundle was improved due to increasing pressure. Flexural strength of the preforms with 1 MPa and 17 MPa indicated almost same value. The result suggested that increasing of pressure did not cause any change in fiber properties. In the effects of pressure on the composites, the composites with 17 MPa was exhibited improvement in bulk density and mechanical property, compared with that with 1 MPa.展开更多
Due to their simple hardware,sensor nodes in IoT are vulnerable to attack,leading to data routing blockages or malicious tampering,which significantly disrupts secure data collection.An Intelligent Active Probing and ...Due to their simple hardware,sensor nodes in IoT are vulnerable to attack,leading to data routing blockages or malicious tampering,which significantly disrupts secure data collection.An Intelligent Active Probing and Trace-back Scheme for IoT Anomaly Detection(APTAD)is proposed to collect integrated IoT data by recruiting Mobile Edge Users(MEUs).(a)An intelligent unsupervised learning approach is used to identify anomalous data from the collected data by MEUs and help to identify anomalous nodes.(b)Recruit MEUs to trace back and propose a series of trust calculation methods to determine the trust of nodes.(c)The last,the number of active detection packets and detection paths are designed,so as to accurately identify the trust of nodes in IoT at the minimum cost of the network.A large number of experimental results show that the recruiting cost and average anomaly detection time are reduced by 6.5 times and 34.33%respectively,while the accuracy of trust identification is improved by 20%.展开更多
Attention mechanism has been a successful method for multimodal affective analysis in recent years. Despite the advances, several significant challenges remain in fusing language and its nonverbal context information....Attention mechanism has been a successful method for multimodal affective analysis in recent years. Despite the advances, several significant challenges remain in fusing language and its nonverbal context information. One is to generate sparse attention coefficients associated with acoustic and visual modalities, which helps locate critical emotional se-mantics. The other is fusing complementary cross‐modal representation to construct optimal salient feature combinations of multiple modalities. A Conditional Transformer Fusion Network is proposed to handle these problems. Firstly, the authors equip the transformer module with CNN layers to enhance the detection of subtle signal patterns in nonverbal sequences. Secondly, sentiment words are utilised as context conditions to guide the computation of cross‐modal attention. As a result, the located nonverbal fea-tures are not only salient but also complementary to sentiment words directly. Experi-mental results show that the authors’ method achieves state‐of‐the‐art performance on several multimodal affective analysis datasets.展开更多
The flow visualization technique using shear-sensitive liquid crystal is applied to the investigation of a Mach 2 internal supersonic flow with pseudo-shock wave (PSW) in a pressure-vacuum supersonic wind tunnel. It...The flow visualization technique using shear-sensitive liquid crystal is applied to the investigation of a Mach 2 internal supersonic flow with pseudo-shock wave (PSW) in a pressure-vacuum supersonic wind tunnel. It provides qualitative information mainly concerning the overall flow structure, such as the turbulent boundary layer separation, reattachment locations and the dimensionalities of the flow. Besides, it can also give understanding of the surface streamlines, vortices in separation region and the corner effect of duct flow. Two kinds of crystals with different viscosities are used in experiments to analyze the viscosity effect. Results are compared with schlieren picture, confirming the effectiveness of liquid crystal in flow-visualization.展开更多
The development of communication technologies which support traffic-intensive applications presents new challenges in designing a real-time traffic analysis architecture and an accurate method that suitable for a wide...The development of communication technologies which support traffic-intensive applications presents new challenges in designing a real-time traffic analysis architecture and an accurate method that suitable for a wide variety of traffic types.Current traffic analysis methods are executed on the cloud,which needs to upload the traffic data.Fog computing is a more promising way to save bandwidth resources by offloading these tasks to the fog nodes.However,traffic analysis models based on traditional machine learning need to retrain all traffic data when updating the trained model,which are not suitable for fog computing due to the poor computing power.In this study,we design a novel fog computing based traffic analysis system using broad learning.For one thing,fog computing can provide a distributed architecture for saving the bandwidth resources.For another,we use the broad learning to incrementally train the traffic data,which is more suitable for fog computing because it can support incremental updates of models without retraining all data.We implement our system on the Raspberry Pi,and experimental results show that we have a 98%probability to accurately identify these traffic data.Moreover,our method has a faster training speed compared with Convolutional Neural Network(CNN).展开更多
基金Project(2005L186) supported by Educational Department of Liaoning Province, China
文摘A series of experiments were conducted for Al-1.65%Si (mass fraction) alloy melt to study the formation of grain refining structure with ultrasonic stirring. The cooling curves of ingots with ultrasonic were measured and compared with those without ultrasonic. At the same time, the effect of the time of ultrasonic stirring on solidification structure of ingots was investigated. The influence of ultrasonic on the grain-refining efficiency of ingots was analyzed. In order to well understand the melts behavior under ultrasonic, by using ammonium chloride solution, the simulation experiment was carried out and the temperature distribution in ingot with or without ultrasonic was compared. The results indicate that the ultrasonic reduces the temperature inhomogeneity of melt, i.e. the ultrasonic helps to homogenize the melt temperature. The effect of stirring and heat generation in ingot start to occur with increasing the time of ultrasonic stirring.
基金partially supported by International Academic Exchange Program of Muroran Institute of Technology,Muroran(Japan)University of Science and Technology Beijing,Beijing(China)+1 种基金Environmentally Friendly Materials Education Program provided by Muroran MATERIAsupported by Beijing Key Laboratory of Energy Conservation and Emission Reduction for Metallurgical Industry,Beijing,China
文摘The effects of partial substitution of La by Ce and Ni by Al, Fe, or Co in LaNi_5-based alloys on hydrogen storage performance were systematically studied. All samples were prepared using vacuum arc melting in an argon atmosphere. The results showed that for LaNi_(5-x)M_x(M = Al, Fe, or Co) alloys, the lattice constants and unit cell volumes increased with an increasing amount of Al and Fe. On the other hand, these parameters decreased upon partial substitution of La by Ce. In addition, the lattice constant remained almost constant in the La_(0.6)Ce_(0.4)Ni_(5–x)Cox alloys regardless of the value of x(x = 0.3, 0.6, or 0.9), as Ce might enhance the homogeneity of the CaCu_5-type phase in Co-containing alloys. The hydrogen storage properties of the alloys were investigated using pressure, composition, and temperature isotherms. The experimental results showed that the plateau pressure decreased with an increasing content of Al, Fe, or Co, but it increased with Ce addition. Furthermore, the plateau pressures of all Co-containing alloys were almost identical upon substitution with Ce. Finally, the enthalpy(ΔH) and entropy(ΔS) values for all alloys were calculated using van't Hoff plots. The relationship between the lattice parameters and enthalpy changes for hydrogenation will be discussed.
基金supported in part by a Grant-in-Aid for Encouragement of Young Scientists A (No.21681010) from the Ministry of Education,Culture,Sports,Science and Technology of Japansupported in part by a Grant-in-Aid for Encouragement of Young Scientists B (No.19710060) from the Ministry of Education,Culture,Sports,Science and Technology of Japan
文摘Removal experiments of phenol, aniline, 2,4-dichlorophenol, nonylphenol and bisphenol A (BPA) using Spirodela polyrrhiza- bacterial associations revealed that all compounds but BPA underwent accelerated removal. The mechanisms differed depending on the substrates. It was found that S. polyrrhiza has a great ability to release phenolic compound-rich root exudates, and the exudates seem to stimulate bacterial degradation of a variety of aromatic compounds.
基金financial supports from plan program of Dalian(grants No.2001145)
文摘The tungsten-inert-gas (TIG) arc welding experiments of cemented carbide YG30 and steel 45 were carried out using the Ni-Fe-C filling alloys. The eta phases and mechanical properties of welded joints were analyzed by means of scanning electronic microscope (SEM), transmission electronic microscope (TEM) coupled with selected diffraction, electronic probe microanalysis and bending strength methods. The experimental results show that the chemical composition of the filling alloys affects eta phase formation. When the carbon and nickel contents in filling alloys are 0.61 wt% and 55.29 wt%, respectively, no eta phases form. And the joint bending strength is the highest to 1.352 GPa. But if they are 0.01wt% and 55.38wt%, the eta phases are formed at the boundaries of the cemented carbide and the weld, and the thickness of eta phase layer is about 110 micrometers. And the joint bending strength is low. Usually, these eta phases are anomalously granular, and easy to accumulate at the boundaries between cemented carbides and the weld. They are multiple M_6C rich in tungsten and iron.
文摘Objective:To evaluate the neuroprotective effects of the organic components of scallop shells(scallop shell extract) on memory impairment and locomotor activity induced by scopolamine or 5-methyl-10,11-dihydro-5H-dibenzo(a,d) cyclohepten-5,10-imine(MK801).Methods:Effect of the scallop shell extract on memory impairment and locomotor activity was investigated using the Y-maze test,the Morris water maze test,and the open field test.Results:Scallop shell extract significantly reduced scopolamine-induced short-term memory impairment and partially reduced scopolamine-induced spatial memory impairment in the Morris water maze test.Scallop shell extract suppressed scopolamine-induced elevation of acetylcholine esterase activity in the cerebral cortex.Treatment with scallop shell extract reversed the increase in locomotor activity induced by scopolamine.Scallop shell extract also suppressed the increase in locomotor activity induced by MK801.Conclusions:Our results provide initial evidence that scallop shell extract reduces scopolamine-induced memory impairment and suppresses MK-801-induced hyperlocomotion.
基金supported by JSPS KAKENHI Grant Numbers JP16K00117, JP19K20250 and KDDI Foundation
文摘Initially as an extension of cloud computing, fog computing has been inspiring new ideas about moving computing tasks to the edge of networks. In fog, we often repeat the procedure of placing services because of the geographical distribution of mobile users. We may not expect a fixed demand and supply relationship between users and service providers since users always prefer nearby service with less time delay and transmission consumption. That is, a plug-and-play service mode is what we need in fog. In this paper, we put forward a dynamic placement strategy for fog service to guarantee the normal service provision and optimize the Quality of Service (QoS). The simulation results show that our strategy can achieve better performance under metrics including energy consumption and end-to-end latency. Moreover, we design a real Plug-and-Play Fog (PnPF) based on Raspberry Pi and OpenWrt to provide fog services for wireless multimedia networks.
文摘To study the effect of impingement surface geometry, a cavitation erosion experiment was conducted using a submerged cavitating jet rig with hydraulic oil. The test setup comprised a test chamber with a long-orifice nozzle, a hydraulic pump with an electric motor, hydraulic auxiliaries, including valves, a cooler, a filter, a reservoir, and measuring instruments, including pressure gages and a thermometer. Hexahedral specimens made of aluminum alloy with flat and grooved surfaces and oblique angles were prepared. Hydraulic oil with a viscosity grade of 32 was used at 40°C as the test fluid. The upstream absolute pressure was kept at 10.1 MPa and the cavitation numbers were set at 0.02 - 0.04. The results of this experiment yielded the following conclusions. The mass loss of the grooved specimens did not increase monotonically as the exposure time increased. The standoff distances at the maximum mass loss for the flat and grooved specimens were almost equivalent. The mass loss decreased as the oblique angle increased and the cavitation number increased, regardless of the presence of grooves. The surfaces were eroded in a ring-like region, but the region elongated as the angle increased. For the grooved specimens, the ridges on the ring were eroded, and when the directions of the grooves and the flow matched, the roots and flanks were severely eroded.
基金the Muroran Institute of Technology for funding this project
文摘The objective of this investigation is to study the influence of vanadium(5.0wt%–10.0wt%) and chromium(0–9.0wt%) on the microstructure and hardness of Cr-V-Mn-Ni white cast irons with spheroidal vanadium carbides. The alloys' microstructural features are presented and discussed with regard to the distribution of phase elements. The structural constituents of the alloys are spheroidal VC, proeutectoid cementite, ledeburite eutectic, rosette-shaped carbide eutectic(based on M7C3), pearlite, martensite, and austenite. Their combinations and area fraction(AF) ratios are reported to be influenced by the alloys' chemical composition. Spheroidized VC particles are found to be sites for the nucleation of carbide eutectics. Cr and V are shown to substitute each other in the VC and M7C3 carbides, respectively. Chromium alloying leads to the formation of a eutectic(γ-Fe + М7С3), preventing the appearance of proeutectoid cementite in the structure. Vanadium and chromium are revealed to increase the total carbide fraction and the amount of austenite in the matrix. Cr is observed to play a key role in controlling the metallic matrix microstructure.
文摘Full factorial design was used to evaluate the two-body abrasive resistance of 3wt%C–4wt%Mn–1.5wt%Ni spheroidal carbide cast irons with varying vanadium(5.0wt%–10.0wt%) and chromium(up to 9.0wt%) contents. The alloys were quenched at 920℃. The regression equation of wear rate as a function of V and Cr contents was proposed. This regression equation shows that the wear rate decreases with increasing V content because of the growth of spheroidal VC carbide amount. Cr influences the overall response in a complex manner both by reducing the wear rate owing to eutectic carbides(M7C3) and by increasing the wear rate though stabilizing austenite to deformation-induced martensite transformation. This transformation is recognized as an important factor in increasing the abrasive response of the alloys. By analyzing the regression equation, the optimal content ranges are found to be 7.5wt%–10.0wt% for V and 2.5wt%–4.5wt% for Cr, which corresponds to the alloys containing 9vol%–15vol% spheroidal VC carbides, 8vol%–16vol% M7C3, and a metastable austenite/martensite matrix. The wear resistance is 1.9–2.3 times that of the traditional 12wt% V–13wt% Mn spheroidal carbide cast iron.
基金Supported by the National Natural Science Foundation of China under Grant No 51461035the Photon Factory Program Advisory Committee under Grant Nos 2007G857,2010G099,2012G095 and 2014G047
文摘We perform the extended x-ray absorption tlne structure (EXAFS) measurement to investigate the local structure of amorphous alloys CexRu100-x (x = 9, 43 and 80). The interatomic distances of the nearest Ru-Ce and Ru-Ru pairs derived from EXAFS are fully independent of Ce concentration. On the other hand the distance between neighboring Ce atoms increases sharply with the Ce content, which is exactly proportional to the Ce effective magnetic moment. We discuss the relation between the atomic distance and the effective magnetic moment from the point of view of the magneto-volume effect.
基金supported by the National Natural Science Foundation of China under Grant 92046001,61962009,the JSPS KAKENHI Grant Numbers JP19K20250,JP20H04174,JP22K11989Leading Initiative for Excellent Young Researchers (LEADER),MEXT,Japan,and JST,PRESTO Grant Number JPMJPR21P3+1 种基金Japan.Mianxiong Dong is the corresponding author,the Doctor Scientific Research Fund of Zhengzhou University of Light Industry under Grant 2021BSJJ033Key Scientific Research Project of Colleges and Universities in Henan Province (CN)under Grant No.22A413010.
文摘Internet of Medical Things(IoMT)plays an essential role in collecting and managing personal medical data.In recent years,blockchain technology has put power in traditional IoMT systems for data sharing between different medical institutions and improved the utilization of medical data.However,some problems in the information transfer process between wireless medical devices and mobile medical apps,such as information leakage and privacy disclosure.This paper first designs a cross-device key agreement model for blockchain-enabled IoMT.This model can establish a key agreement mechanism for secure medical data sharing.Meanwhile,a certificateless authenticated key agreement(KA)protocol has been proposed to strengthen the information transfer security in the cross-device key agreement model.The proposed KA protocol only requires one exchange of messages between the two parties,which can improve the protocol execution efficiency.Then,any unauthorized tampering of the transmitted signed message sent by the sender can be detected by the receiver,so this can guarantee the success of the establishment of a session key between the strange entities.The blockchain ledger can ensure that the medical data cannot be tampered with,and the certificateless mechanism can weaken the key escrow problem.Moreover,the security proof and performance analysis are given,which show that the proposed model and KA protocol are more secure and efficient than other schemes in similar literature.
文摘Extracting approximate symmetry planes is a challenge due to the difficulty of accurately measuring numerical values. Introducing the approximate symmetry planes of a 3D point set, this paper presents a new method by gathering normal vectors of potential of the planes, clustering the high probability ones, and then testing and verifying the planes. An experiment showed that the method is effective, robust and universal for extracting the complete approximate planes of symmetry of a random 3D point set.
文摘Through experimental analysis of the liquid flows in a flow channel instrument, prompt evaluation of the physically defined viscosity of non-Newtonian liquid foods was investigated for development into a structurally simple and easy-to-use viscometer. For Newtonian and non-Newtonian test liquids, a relation between the friction coefficient and Reynolds number, which was dimensionless as derived from an expression of analysis as a gravity current, indicated a condition under which the flow in the instrument was laminar and under which an average shear rate was on the order of less than 1 s~. Prediction organized based on this empirical relation reproduced practically the flow curve determined for the liquid foods using a rotor type viscometer. Utilization of the channel instrument as a viscometer was formulated in terms of physical meanings of measurements such as the flow length and elapsed time.
基金supported in part by The Japan Society for the Promotion of Science(Scientific Research C)of Japan under Project 18K04076.
文摘Consequent-pole permanent magnet synchronous machines(CP-PMSMs)have attracted considerable interest as a means of reducing manufacturing costs through a marked reduction in the volume of permanent magnet required to meet a particular torque specification.In this paper,novel rotor topologies for a CP-PMSM are derived to unlock the full design space potential.The ON/OFF method is introduced to manage the laminated steel material distribution over the rotor region,high average torque and low torque ripple are the objects of rotor design,and the immune algorithm is used to search for the optimal material distribution for the formulated problem.More than 9000 different rotor topologies are created and evaluated within 12 hours by this methodology.The optimal topologies under different design strategy are presented,and performance of these topologies are analyzed.The analysis results show that the proposed methodology can deliver novel rotor topologies for the CP-PMSM with surprising torque quality since the torque ripple is suppressed to a low level with no average torque sacrifice.
文摘The nano-infiltration and transient eutectic-phase (NITE) method is one of the most attractive methods for fabrication of SiC and SiC/SiC composites. In the NITE method, preform densification is essential option for damage less near-net shaping technique. However, optimization of preform densification is insufficient yet. The objective of this study is to evaluate the effects of pressure during preform densification on SiC/SiC composites. The preform before preform densification has many pores in the inter-prepreg sheets. These pores were disappeared by preform densification. As the effects of pressure on preform, densification in the intra-fiber-bundle was improved due to increasing pressure. Flexural strength of the preforms with 1 MPa and 17 MPa indicated almost same value. The result suggested that increasing of pressure did not cause any change in fiber properties. In the effects of pressure on the composites, the composites with 17 MPa was exhibited improvement in bulk density and mechanical property, compared with that with 1 MPa.
基金supported by the National Natural Science Foundation of China(62072475)the Fundamental Research Funds for the Central Universities of Central South University(CX20230356)。
文摘Due to their simple hardware,sensor nodes in IoT are vulnerable to attack,leading to data routing blockages or malicious tampering,which significantly disrupts secure data collection.An Intelligent Active Probing and Trace-back Scheme for IoT Anomaly Detection(APTAD)is proposed to collect integrated IoT data by recruiting Mobile Edge Users(MEUs).(a)An intelligent unsupervised learning approach is used to identify anomalous data from the collected data by MEUs and help to identify anomalous nodes.(b)Recruit MEUs to trace back and propose a series of trust calculation methods to determine the trust of nodes.(c)The last,the number of active detection packets and detection paths are designed,so as to accurately identify the trust of nodes in IoT at the minimum cost of the network.A large number of experimental results show that the recruiting cost and average anomaly detection time are reduced by 6.5 times and 34.33%respectively,while the accuracy of trust identification is improved by 20%.
基金National Key Research and Development Plan of China, Grant/Award Number: 2021YFB3600503National Natural Science Foundation of China, Grant/Award Numbers: 62276065, U21A20472。
文摘Attention mechanism has been a successful method for multimodal affective analysis in recent years. Despite the advances, several significant challenges remain in fusing language and its nonverbal context information. One is to generate sparse attention coefficients associated with acoustic and visual modalities, which helps locate critical emotional se-mantics. The other is fusing complementary cross‐modal representation to construct optimal salient feature combinations of multiple modalities. A Conditional Transformer Fusion Network is proposed to handle these problems. Firstly, the authors equip the transformer module with CNN layers to enhance the detection of subtle signal patterns in nonverbal sequences. Secondly, sentiment words are utilised as context conditions to guide the computation of cross‐modal attention. As a result, the located nonverbal fea-tures are not only salient but also complementary to sentiment words directly. Experi-mental results show that the authors’ method achieves state‐of‐the‐art performance on several multimodal affective analysis datasets.
文摘The flow visualization technique using shear-sensitive liquid crystal is applied to the investigation of a Mach 2 internal supersonic flow with pseudo-shock wave (PSW) in a pressure-vacuum supersonic wind tunnel. It provides qualitative information mainly concerning the overall flow structure, such as the turbulent boundary layer separation, reattachment locations and the dimensionalities of the flow. Besides, it can also give understanding of the surface streamlines, vortices in separation region and the corner effect of duct flow. Two kinds of crystals with different viscosities are used in experiments to analyze the viscosity effect. Results are compared with schlieren picture, confirming the effectiveness of liquid crystal in flow-visualization.
基金supported by JSPS KAKENHI Grant Number JP16K00117, JP19K20250KDDI Foundationthe China Scholarship Council (201808050016)
文摘The development of communication technologies which support traffic-intensive applications presents new challenges in designing a real-time traffic analysis architecture and an accurate method that suitable for a wide variety of traffic types.Current traffic analysis methods are executed on the cloud,which needs to upload the traffic data.Fog computing is a more promising way to save bandwidth resources by offloading these tasks to the fog nodes.However,traffic analysis models based on traditional machine learning need to retrain all traffic data when updating the trained model,which are not suitable for fog computing due to the poor computing power.In this study,we design a novel fog computing based traffic analysis system using broad learning.For one thing,fog computing can provide a distributed architecture for saving the bandwidth resources.For another,we use the broad learning to incrementally train the traffic data,which is more suitable for fog computing because it can support incremental updates of models without retraining all data.We implement our system on the Raspberry Pi,and experimental results show that we have a 98%probability to accurately identify these traffic data.Moreover,our method has a faster training speed compared with Convolutional Neural Network(CNN).