In the past few decades, applications of geostationary orbit (GEO) satellites have attracted increasing attention, and with the development of optical technologies, GEO optical satellites have become popular worldwide...In the past few decades, applications of geostationary orbit (GEO) satellites have attracted increasing attention, and with the development of optical technologies, GEO optical satellites have become popular worldwide. This paper proposes a general working pattern for a GEO optical satellite, as well as a target observation mission planning model. After analyzing the requirements of users and satellite control agencies, two objectives are simultaneously considered: maximization of total profit and minimization of satellite attitude maneuver angle. An NSGA-II based multi-objective optimization algorithm is proposed, which contains some heuristic principles in the initialization phase and mutation operator, and is embedded with a traveling salesman problem (TSP) optimization. The validity and performance of the proposed method are verified by extensive numerical simulations that include several types of point target distributions.展开更多
The sensible and latent heat fluxes over the ocean area near China were calculated and analyzed by usingthe Goddard Earth Observing System (GEOS) - four-dimensional Data Assimilation System (DAS). The calculated resul...The sensible and latent heat fluxes over the ocean area near China were calculated and analyzed by usingthe Goddard Earth Observing System (GEOS) - four-dimensional Data Assimilation System (DAS). The calculated results showed that the sensible heat flux had its large value in winter and autumn , small value in spring and summer overthe ocean area near China. In winter, the sensible heat flux increased distinctly with latitude, and its isolines were verycrowded. Over the ocean area east of Taiwan Province and south of Japan, the direction of isoline was from southwestto northeast. In the South China Sea the sensible heat flux was lower than that of surrounding ocean areas,and its isoline was distributed into a type of an inverted trough. In autumn and winter, the maximum center of latent heat flux appeared over the ocean area northeast of Taiwan Province and south and southeast of Japan, meanwhile, the isoline wasin the direction of southwest to northeast. In spring and summer, the latent heat flux had minimum value in the Huanghai Sea. At the same time, the maximum value center of latent heat flux appeared over the ocean area south of Japan inspring.展开更多
There are mounting evidences that human consume significant quantities of resources and have a major impact on the environment. Some research indicates that since the 1980s human demands on the biosphere have exceeded...There are mounting evidences that human consume significant quantities of resources and have a major impact on the environment. Some research indicates that since the 1980s human demands on the biosphere have exceeded its regen-errative capacity. One way to solve this problem is to minimize the inappropriate ex-ploitation from environment. This essay wil focus on energy self-sustained project, which is a specific way to reduce energy requirements. Energy self-sustained project refers to that energy production is equal to the amount consumed. Three concepts are quoted in the fol-lowing to assess whether the project achieve zero-energy or not. First, ecological footprint, which provides an indication of the human load on the biosphere, is uti-lized to measure the inputs and outputs of the bioregion, which is also beneficial for defining the potential energy. Another one is life cycle assessment, which evaluates environmental load that relates to the entire life periodic system of a product, is helpful to measure the products used in the energy self sustained project. In addi-tion, net energy, and gross resource abundance, definitions for selection, or hierar-chy of different energy resources, can evaluate the new energy resources in project. Geos Neighbourhood, located in colorado, was planned as the largest net-zero energy neighbourhood in the United States. To meet the energy self sustainability, earth and sun power completely sustain the community＇s energy needs, and re-place al fossil fuels. Compared with the traditional communities, Geos Neighbour-hood minimize the adverse impact on the environment. As tools for assessment, ecological footprint, life circle assessment, and net energy, are al used to analyse the planning and design principles in the neighbourhood. By the research, the de-sign principles and energy use in Geos Neighbourhood wil be re-examined that whether the zero energy project achieves the reduction of ecological footprint, and energy self sustainability. In addition, life circle assessment wil re-examine the ma-terials used in the community also. Final y, the concept of ＇net energy＇ wil test solar energy and earth power which is the major energy used in Geos Neighbour-hood.展开更多
The impacts of ionospheric scintillation on geosynchronous synthetic aperture radar（GEO SAR）focusing is studied based on the multiple phase screen（MPS）theory.The power spectrum density of electron irregularities i...The impacts of ionospheric scintillation on geosynchronous synthetic aperture radar（GEO SAR）focusing is studied based on the multiple phase screen（MPS）theory.The power spectrum density of electron irregularities is first modified according to the ionospheric anisotropy.Then propagation wave equations in random medium are deduced in the case of oblique incidence in GEO SAR.The amplitude and phase errors induced by the random electron fluctuations are generated by the iterated MPS simulations and are superimposed into the GEO SAR signals.Through the following imaging and evaluation,the effects of the anisotropic ionospheric scintallition on GEO SAR are assessed.At last,the optimized integration time under different ionospheric scintillation conditions are recommended through Monte Carlo experiments.It is concluded that,greater ionospheric fluctuations and longer integration time will result in more severe deterioration,even no focus at all in the worst case.展开更多
The architecture of cislunar multi-hop communication networks, which focuses on the requirements of lunar full-coverage and continuous cislunar communications, is presented on the basis of Geosynchronous Orbit (GEO) s...The architecture of cislunar multi-hop communication networks, which focuses on the requirements of lunar full-coverage and continuous cislunar communications, is presented on the basis of Geosynchronous Orbit (GEO) satellite network relays. According to the geographical distribution of the forthcoming Chinese Deep Space Measuring and Controlling Network (DSMCN), two networking schemes are proposed and two elevation angle optimization models are established for locating GEO relay satellites. To analyze the dynamic connectivity, a dynamic network model is constructed with respect to the time-varying characteristics of cislunar trunk links. The advantages of the two proposed schemes, in terms of the Connectivity Rate (CR), Interruption Frequency (IF), and Average Length of Connecting Duration (ALCD), are corroborated by several simulations. In the case of the lunar polar orbit constellation case, the gains in the performance of scheme I are observed to be 134.55%, 117.03%, and 217.47% compared with DSMCN for three evaluation indicators, and the gains in the performance of scheme II are observed to be 238. 22%, 240.40%, and 572.71%. The results validate that the connectivity of GEO satellites outperforms that of earth facilities significantly and schemes based on GEO satellite relays are promising options for cislunar multi-hop communication networking.展开更多
基金supported by the National Natural Science Foundation of China(7150118061473301)
文摘In the past few decades, applications of geostationary orbit (GEO) satellites have attracted increasing attention, and with the development of optical technologies, GEO optical satellites have become popular worldwide. This paper proposes a general working pattern for a GEO optical satellite, as well as a target observation mission planning model. After analyzing the requirements of users and satellite control agencies, two objectives are simultaneously considered: maximization of total profit and minimization of satellite attitude maneuver angle. An NSGA-II based multi-objective optimization algorithm is proposed, which contains some heuristic principles in the initialization phase and mutation operator, and is embedded with a traveling salesman problem (TSP) optimization. The validity and performance of the proposed method are verified by extensive numerical simulations that include several types of point target distributions.
文摘The sensible and latent heat fluxes over the ocean area near China were calculated and analyzed by usingthe Goddard Earth Observing System (GEOS) - four-dimensional Data Assimilation System (DAS). The calculated results showed that the sensible heat flux had its large value in winter and autumn , small value in spring and summer overthe ocean area near China. In winter, the sensible heat flux increased distinctly with latitude, and its isolines were verycrowded. Over the ocean area east of Taiwan Province and south of Japan, the direction of isoline was from southwestto northeast. In the South China Sea the sensible heat flux was lower than that of surrounding ocean areas,and its isoline was distributed into a type of an inverted trough. In autumn and winter, the maximum center of latent heat flux appeared over the ocean area northeast of Taiwan Province and south and southeast of Japan, meanwhile, the isoline wasin the direction of southwest to northeast. In spring and summer, the latent heat flux had minimum value in the Huanghai Sea. At the same time, the maximum value center of latent heat flux appeared over the ocean area south of Japan inspring.
文摘There are mounting evidences that human consume significant quantities of resources and have a major impact on the environment. Some research indicates that since the 1980s human demands on the biosphere have exceeded its regen-errative capacity. One way to solve this problem is to minimize the inappropriate ex-ploitation from environment. This essay wil focus on energy self-sustained project, which is a specific way to reduce energy requirements. Energy self-sustained project refers to that energy production is equal to the amount consumed. Three concepts are quoted in the fol-lowing to assess whether the project achieve zero-energy or not. First, ecological footprint, which provides an indication of the human load on the biosphere, is uti-lized to measure the inputs and outputs of the bioregion, which is also beneficial for defining the potential energy. Another one is life cycle assessment, which evaluates environmental load that relates to the entire life periodic system of a product, is helpful to measure the products used in the energy self sustained project. In addi-tion, net energy, and gross resource abundance, definitions for selection, or hierar-chy of different energy resources, can evaluate the new energy resources in project. Geos Neighbourhood, located in colorado, was planned as the largest net-zero energy neighbourhood in the United States. To meet the energy self sustainability, earth and sun power completely sustain the community＇s energy needs, and re-place al fossil fuels. Compared with the traditional communities, Geos Neighbour-hood minimize the adverse impact on the environment. As tools for assessment, ecological footprint, life circle assessment, and net energy, are al used to analyse the planning and design principles in the neighbourhood. By the research, the de-sign principles and energy use in Geos Neighbourhood wil be re-examined that whether the zero energy project achieves the reduction of ecological footprint, and energy self sustainability. In addition, life circle assessment wil re-examine the ma-terials used in the community also. Final y, the concept of ＇net energy＇ wil test solar energy and earth power which is the major energy used in Geos Neighbour-hood.
基金Supported by the National Natural Science Foundation of China(61225005,61427802,61471038,61120106004)Chang Jiang Scholars Program(T2012122)+1 种基金111 project of China(B14010)Beijing Higher Education Young Elite Teacher Project(YETP1168)
文摘The impacts of ionospheric scintillation on geosynchronous synthetic aperture radar（GEO SAR）focusing is studied based on the multiple phase screen（MPS）theory.The power spectrum density of electron irregularities is first modified according to the ionospheric anisotropy.Then propagation wave equations in random medium are deduced in the case of oblique incidence in GEO SAR.The amplitude and phase errors induced by the random electron fluctuations are generated by the iterated MPS simulations and are superimposed into the GEO SAR signals.Through the following imaging and evaluation,the effects of the anisotropic ionospheric scintallition on GEO SAR are assessed.At last,the optimized integration time under different ionospheric scintillation conditions are recommended through Monte Carlo experiments.It is concluded that,greater ionospheric fluctuations and longer integration time will result in more severe deterioration,even no focus at all in the worst case.
基金supported by the National High Technology Research and Development Program of P.R.China under Grant No.2012 AA121604 the National Natural Science Foundation of China under Grants No.60902042,No.61170014,No.61202079+1 种基金 the National Research Foundation for the Doctoral Program of Higher Education of China under Grant No.20090006110014 the Foundation for Key Program of Ministry of Education of China under Grant No.311007
文摘The architecture of cislunar multi-hop communication networks, which focuses on the requirements of lunar full-coverage and continuous cislunar communications, is presented on the basis of Geosynchronous Orbit (GEO) satellite network relays. According to the geographical distribution of the forthcoming Chinese Deep Space Measuring and Controlling Network (DSMCN), two networking schemes are proposed and two elevation angle optimization models are established for locating GEO relay satellites. To analyze the dynamic connectivity, a dynamic network model is constructed with respect to the time-varying characteristics of cislunar trunk links. The advantages of the two proposed schemes, in terms of the Connectivity Rate (CR), Interruption Frequency (IF), and Average Length of Connecting Duration (ALCD), are corroborated by several simulations. In the case of the lunar polar orbit constellation case, the gains in the performance of scheme I are observed to be 134.55%, 117.03%, and 217.47% compared with DSMCN for three evaluation indicators, and the gains in the performance of scheme II are observed to be 238. 22%, 240.40%, and 572.71%. The results validate that the connectivity of GEO satellites outperforms that of earth facilities significantly and schemes based on GEO satellite relays are promising options for cislunar multi-hop communication networking.
文摘目的:探讨在生物信息学方法指导下骨质疏松症(osteoporosis,OP)不同病因病机的治疗要点。方法:以滋补肝肾、益气健脾、活血化瘀代表药物为搜索词,在中药系统药理数据库检索活性成分及预测靶点,借助Cytoscape 3.7.2软件构建药物与靶点之间的网络图。通过基因表达数据库(gene expression omnibus database,GEO)相关芯片分析差异基因,结合疾病数据库获取OP所有疾病靶点并构建药物与疾病的关键靶点韦恩图。通过DAVID数据库对关键靶点进行基因本体及京都基因与基因组百科全书富集,以探讨不同病因病机下OP的防治要点。结果:滋补肝肾、益气健脾及活血化瘀组分别筛选出146个、126个及117个靶点,GEO数据库筛选出1173个差异基因,疾病数据库筛选出靶点336个,去重整合后共获得OP靶点1469个。滋补肝肾、益气健脾组映射出25个相同靶点,活血化瘀组映射出21个关键靶点。基因可视化分析发现肝肾亏虚及脾胃虚弱型OP的治疗要点,且主要集中在肿瘤坏死因子通路、核苷酸结合寡聚化结构域样受体通路等方面;气血瘀阻型的治疗要点主要在血管内皮生长因子通路、缺氧诱导因子1通路等方面。结论:OP具有复杂的病因病机,在对症治疗时,肝肾亏虚及脾胃虚弱型更应注重控制体内炎症水平,气血瘀阻型更应注意体内局部血管构建及纠正缺氧状态。同时,众多病因病机之间存在着相似病理过程,也应注重全面调控及防治。
