A radio wave driven by Orbital angular momentum(OAM) is called a vortex radio and has a helical wavefront. The differential helical wavefronts of several vortex radios are closely related to their topological charges ...A radio wave driven by Orbital angular momentum(OAM) is called a vortex radio and has a helical wavefront. The differential helical wavefronts of several vortex radios are closely related to their topological charges or mode numbers. In physics, two or more radio waves with different mode numbers are orthogonal to their azimuth angles. With the development of radio communication technologies, some researchers have been exploring the OAM-based multi-mode multiplexing(multi-OAM-mode multiplexing) technologies in order to enhance the channel spectrum efficiency(SE) of a radio communication system by using the orthogonal properties of vortex radios. After reviewing the reported researches of OAM-based radio communication, we find that some breakthroughs have been made in the combination of OAM and traditional Multi-Input-Multi-Output(MIMO). However, the existing technology is not sufficient to support OAM-based MIMO system to achieve maximum the channel SE. To maximize the spectrum efficiency of OAM-based MIMO system, we present a reused multi-OAM-mode multiplexing vortex radio(RMMVR) MIMO system, which is based on fractal uniform cir-cular arrays(UCAs). The scheme described in this study can effectively combine multiOAM-mode multiplexing with MIMO spatial multiplexing. First, we present the generation of RMMVR MIMO signals. Second, under line-of-sight(LOS) propagation conditions, we derive the channels of the RMMVR MIMO system. Third, we separate the RMMVR MIMO signals using an orthogonal separation method based on full azimuth sampling. Finally, we introduce the method for calculating the channel capacity of the RMMVR MIMO system. Theoretical analysis shows that the scheme proposed in this study is feasible. Moreover, the simulation results show that spatial and mode diversity are obtained by exploiting fractal UCAs. However, to enhance the channel SE of RMMVR MIMO system, an interference cancellation method needs to be introduced for zero-mode vortex radios, and some methods of multi-OAM-mode beams convergence and mode power optimization strategy should be introduced in the future.展开更多
The study aimed to develop a vertical crop cultivation system for leafy plants based on cylindrical hydroponics and light emitting diode （LED） technology. Investigations were conducted on growing lettuce （Lactuca s...The study aimed to develop a vertical crop cultivation system for leafy plants based on cylindrical hydroponics and light emitting diode （LED） technology. Investigations were conducted on growing lettuce （Lactuca sativa cv. ＂Rex＂, ＂Nanda＂ and ＂Canasta＂） indoors in a rotary system and Chinese cabbage （Brassica chinensis） in a multi-tier cylindrical hydroponics system under red and blue （RB） LED lightings. Light intensity from different light sources have an influence on the yield and growth behaviour of indoor lettuce. Photosynthetically active radiation （PAR） levels at 63 μmol/m2·s produced low fresh weights （FW） and leaf areas of lettuce ＂Rex＂ and ＂Nanda＂ were grown under rotating conditions. The effect was, however, different on the better developed ＂Canasta＂. Stem etiolation was a common occurrence under such influence. Chlorosis was not observed on all plant types grown under the LEDs. Cultivating Chinese cabbage plants （FW： 28 g/plant） in cylindrical units stacked vertically above another, increased planting density by 47% when compared to the rotary system,展开更多
This work deals with an application in parametric modeling of problems regarding pipelines buried in static system, written in C＋＋ using ObjectARX functions. The application is fully integrated with AutoCAD through ...This work deals with an application in parametric modeling of problems regarding pipelines buried in static system, written in C＋＋ using ObjectARX functions. The application is fully integrated with AutoCAD through saproms.dll and saproms.arx libraries where the stages of pre-processing, processing and post-processing are done in AutoCAD sotlware environment itself without having to export data to another processing environment. The analysis processing is done by functions whose algorithms are based on the solution of the coupling between the FEM （finite element method） and the BEM （boundary element method）. The representation of the homogeneous pipeline is made by the FEM using a finite element in the form of a cylindrical panel called CYS （cylindrical shell）, developed from the homogeneous isotropic model proposed initially by Djoudi Bahai, who uses the philosophy of the assumed deformation model （assumed strain based model）. The soil is taken to be a continuum infinite or semi-infinite elastic solid patterned by BEM where special boundary elements are proposed with curved surface or curved edges to represent the soil-structure interaction mainly in the areas of contact with the pipeline.展开更多
In the present work, an ideal Quadra-pole field has been realized by circular concave electrodes with a proper electrode angle The potential distribution in such an electrode system has been analyzed by assuming a sim...In the present work, an ideal Quadra-pole field has been realized by circular concave electrodes with a proper electrode angle The potential distribution in such an electrode system has been analyzed by assuming a simple boundary condition. The effect of the gap angle between the electrodes of the Quadra-pole lens on the optical properties has been studied such as the focal lengths, magnification and the chromatic aberration coefficient in the convergence and divergence planes.展开更多
基金supported by the National Natural Science Foundation of China(No.61671347)
文摘A radio wave driven by Orbital angular momentum(OAM) is called a vortex radio and has a helical wavefront. The differential helical wavefronts of several vortex radios are closely related to their topological charges or mode numbers. In physics, two or more radio waves with different mode numbers are orthogonal to their azimuth angles. With the development of radio communication technologies, some researchers have been exploring the OAM-based multi-mode multiplexing(multi-OAM-mode multiplexing) technologies in order to enhance the channel spectrum efficiency(SE) of a radio communication system by using the orthogonal properties of vortex radios. After reviewing the reported researches of OAM-based radio communication, we find that some breakthroughs have been made in the combination of OAM and traditional Multi-Input-Multi-Output(MIMO). However, the existing technology is not sufficient to support OAM-based MIMO system to achieve maximum the channel SE. To maximize the spectrum efficiency of OAM-based MIMO system, we present a reused multi-OAM-mode multiplexing vortex radio(RMMVR) MIMO system, which is based on fractal uniform cir-cular arrays(UCAs). The scheme described in this study can effectively combine multiOAM-mode multiplexing with MIMO spatial multiplexing. First, we present the generation of RMMVR MIMO signals. Second, under line-of-sight(LOS) propagation conditions, we derive the channels of the RMMVR MIMO system. Third, we separate the RMMVR MIMO signals using an orthogonal separation method based on full azimuth sampling. Finally, we introduce the method for calculating the channel capacity of the RMMVR MIMO system. Theoretical analysis shows that the scheme proposed in this study is feasible. Moreover, the simulation results show that spatial and mode diversity are obtained by exploiting fractal UCAs. However, to enhance the channel SE of RMMVR MIMO system, an interference cancellation method needs to be introduced for zero-mode vortex radios, and some methods of multi-OAM-mode beams convergence and mode power optimization strategy should be introduced in the future.
文摘The study aimed to develop a vertical crop cultivation system for leafy plants based on cylindrical hydroponics and light emitting diode （LED） technology. Investigations were conducted on growing lettuce （Lactuca sativa cv. ＂Rex＂, ＂Nanda＂ and ＂Canasta＂） indoors in a rotary system and Chinese cabbage （Brassica chinensis） in a multi-tier cylindrical hydroponics system under red and blue （RB） LED lightings. Light intensity from different light sources have an influence on the yield and growth behaviour of indoor lettuce. Photosynthetically active radiation （PAR） levels at 63 μmol/m2·s produced low fresh weights （FW） and leaf areas of lettuce ＂Rex＂ and ＂Nanda＂ were grown under rotating conditions. The effect was, however, different on the better developed ＂Canasta＂. Stem etiolation was a common occurrence under such influence. Chlorosis was not observed on all plant types grown under the LEDs. Cultivating Chinese cabbage plants （FW： 28 g/plant） in cylindrical units stacked vertically above another, increased planting density by 47% when compared to the rotary system,
文摘This work deals with an application in parametric modeling of problems regarding pipelines buried in static system, written in C＋＋ using ObjectARX functions. The application is fully integrated with AutoCAD through saproms.dll and saproms.arx libraries where the stages of pre-processing, processing and post-processing are done in AutoCAD sotlware environment itself without having to export data to another processing environment. The analysis processing is done by functions whose algorithms are based on the solution of the coupling between the FEM （finite element method） and the BEM （boundary element method）. The representation of the homogeneous pipeline is made by the FEM using a finite element in the form of a cylindrical panel called CYS （cylindrical shell）, developed from the homogeneous isotropic model proposed initially by Djoudi Bahai, who uses the philosophy of the assumed deformation model （assumed strain based model）. The soil is taken to be a continuum infinite or semi-infinite elastic solid patterned by BEM where special boundary elements are proposed with curved surface or curved edges to represent the soil-structure interaction mainly in the areas of contact with the pipeline.
文摘In the present work, an ideal Quadra-pole field has been realized by circular concave electrodes with a proper electrode angle The potential distribution in such an electrode system has been analyzed by assuming a simple boundary condition. The effect of the gap angle between the electrodes of the Quadra-pole lens on the optical properties has been studied such as the focal lengths, magnification and the chromatic aberration coefficient in the convergence and divergence planes.
