The YSZ coatings are prepared by the plasma spray-physical vapor deposition(PS-PVD)technology based on a specific experimental design.The structure,thickness and growth angle of YSZ coatings on the entire circumferent...The YSZ coatings are prepared by the plasma spray-physical vapor deposition(PS-PVD)technology based on a specific experimental design.The structure,thickness and growth angle of YSZ coatings on the entire circumferential surface of the cylindrical sample are studied.The results indicated that the structure,thickness and deflection growth angle of YSZ coatings are related to the orientation of deposition location.The numerical simulation of the multiphase mixed fluid near the substrate is carried out and the deposition regularity and mechanism of YSZ coatings prepared by PS-PVD is deduced.The growth rate is related to the local characteristics of the plasma flow field,and is directly proportional to the field pressure and inversely proportional to the field velocity.The growth angle of the coating is generally affected by the flow direction of the plasma jet.Especially,the normal component of velocity vector,V_(norm),mainly affects the speed at which the coating grows vertically upwards.The tangential component of velocity vector,V_(tan),determines the degree that the coating growth direction deviates from the vertical direction.When V_(tan)≠0,the coating forms a fine column with a certain deflection angle and finally develops into an oblique columnar structure.展开更多
Based on the experimental results of the work-hardening processes of single crystals,the ac- commodation processes of polycrvstal deformation and the assumption of idealized polycrystal,the stress-strain relation of e...Based on the experimental results of the work-hardening processes of single crystals,the ac- commodation processes of polycrvstal deformation and the assumption of idealized polycrystal,the stress-strain relation of elasto-plastic deformation crystal was derived.The effect of orientation difference on the mechanical properties of the bicrvstalline specimens of aluminum was simulated by means of the finite element method(FEM)of elasto-plastic crystal.The results are in good agreement with the experimental results made by Clark and Chalmers in 1954.展开更多
Low Earth Orbit (LEO) satellite communications (SATCOM) are important for wireless networks and offer better global wireless access services than higher altitude SATCOM options. SATCOM performance is affected by the n...Low Earth Orbit (LEO) satellite communications (SATCOM) are important for wireless networks and offer better global wireless access services than higher altitude SATCOM options. SATCOM performance is affected by the number of antennas, which is usually constrained by the satellite space. In this paper, the application of dual-polarized technology is considered to assist LEO SATCOM. Compared with single-polarized antennas, dual-polarized antennas utilize two different polarization orientations to transmit and receive data. This can improve the quality of service (QoS) performance, as it allows for twice the amount of data to be transmitted over the same time–frequency resources. Specifically, we characterize the dual-polarized channel in massive multiple-input multiple-output (MIMO) LEO SATCOM and investigate the precoding design for enhancing the system performance. In particular, a precoding optimization problem is formulated, which aims to jointly optimize the system throughput and the QoS performance. We divide the problem into two stages and develop novel algorithms for each stage to obtain the precoding vectors. The numerical results demonstrate that the dual-polarized technology can improve the system throughput, and the proposed algorithm leads to a higher percentage of users achieving their QoS requirements compared to conventional approaches.展开更多
基金the financial support from National Natural Science Foundation of China(51771059)R&D Program in Key Fields of Guangdong Province of China(2019B010936001)+2 种基金National Science and Technology Major Project of China(2017-VI-0010-0081)Science and Technology Project of Guangdong Province of China(2017A070701027,2014B070705007)Sciences Project of Guangdong Academy of China(2019GDASYL-0104022)。
文摘The YSZ coatings are prepared by the plasma spray-physical vapor deposition(PS-PVD)technology based on a specific experimental design.The structure,thickness and growth angle of YSZ coatings on the entire circumferential surface of the cylindrical sample are studied.The results indicated that the structure,thickness and deflection growth angle of YSZ coatings are related to the orientation of deposition location.The numerical simulation of the multiphase mixed fluid near the substrate is carried out and the deposition regularity and mechanism of YSZ coatings prepared by PS-PVD is deduced.The growth rate is related to the local characteristics of the plasma flow field,and is directly proportional to the field pressure and inversely proportional to the field velocity.The growth angle of the coating is generally affected by the flow direction of the plasma jet.Especially,the normal component of velocity vector,V_(norm),mainly affects the speed at which the coating grows vertically upwards.The tangential component of velocity vector,V_(tan),determines the degree that the coating growth direction deviates from the vertical direction.When V_(tan)≠0,the coating forms a fine column with a certain deflection angle and finally develops into an oblique columnar structure.
文摘Based on the experimental results of the work-hardening processes of single crystals,the ac- commodation processes of polycrvstal deformation and the assumption of idealized polycrystal,the stress-strain relation of elasto-plastic deformation crystal was derived.The effect of orientation difference on the mechanical properties of the bicrvstalline specimens of aluminum was simulated by means of the finite element method(FEM)of elasto-plastic crystal.The results are in good agreement with the experimental results made by Clark and Chalmers in 1954.
基金supported by the National Natural Science Foundation of China for Outstanding Young Scholars under grant 62322104the Key Technologies R&D Program of Jiangsu(Prospective and Key Technologies for Industry)under grants BE2022067 and BE2022067-5+3 种基金the Natural Science Foundation of Jiangsu Province under grant BK20231415the Natural Science Foundation on Frontier Leading Technology Basic Research Project of Jiangsu under grant BK20222001the Jiangsu Province Basic Research Project under grant BK20192002the Fundamental Research Funds for the Central Universities under grants 2242022k60007 and 2242023K5003.
文摘Low Earth Orbit (LEO) satellite communications (SATCOM) are important for wireless networks and offer better global wireless access services than higher altitude SATCOM options. SATCOM performance is affected by the number of antennas, which is usually constrained by the satellite space. In this paper, the application of dual-polarized technology is considered to assist LEO SATCOM. Compared with single-polarized antennas, dual-polarized antennas utilize two different polarization orientations to transmit and receive data. This can improve the quality of service (QoS) performance, as it allows for twice the amount of data to be transmitted over the same time–frequency resources. Specifically, we characterize the dual-polarized channel in massive multiple-input multiple-output (MIMO) LEO SATCOM and investigate the precoding design for enhancing the system performance. In particular, a precoding optimization problem is formulated, which aims to jointly optimize the system throughput and the QoS performance. We divide the problem into two stages and develop novel algorithms for each stage to obtain the precoding vectors. The numerical results demonstrate that the dual-polarized technology can improve the system throughput, and the proposed algorithm leads to a higher percentage of users achieving their QoS requirements compared to conventional approaches.
