数字卫星系统简介

卫星电视的节目具有丰富性、时代性、新颖性等特点。本文介绍了数字卫星接收系统的组成及各部分的作用     

接收卫星电视节目时天馈系统的调整方法

接收卫星电视节目时须对接收天线的几何位置及馈源进行调整,才能接收到要收的电视节目。本文主要介绍卫星接收天线的仰角、方位角的计算方法,以及接收双极性卫星电视节目时馈源的调整。     

卫星电视接收及其调整方法

对卫星电视接收系统的性能和指标进行了分析和估算,为建设卫星地面接收站提供了参考和依据,并详细介绍了数字卫星电视节目的调整方法.     

卫星电视接收及其调整方法

对卫星电视接收系统的性能和指标进行了分析和估算，为建设卫星地面接收站提供了参考和依据，并详细介绍了数字卫星电视节目的调整方法．     

C波段数字卫星电视射频接收系统ADS设计与仿真

本文提出了一种工作于C波段的数字卫星电视射频接收系统方案。该系统采用超外差式的结构。构造了接收杌的各个功能模块，并用ADS软件完成了接收链路的系统级仿真，为硬件设计提供了理论依据。     

数字卫星电视接收关键技术探讨

探讨了数字卫星电视接收的几项关键技术，指出留足门限余量；减少相位噪声；实现极化匹配；选择本振频率准确度和稳定度高的高频头(LNB)；避开同频干扰是保证数字卫星电视信号良好接收的关键。     

浅谈卫星抛物面天线的调整

人类社会迈入了21世纪之际，数字化，光纤化、网络化的浪潮正席卷全球。人类进入了知识经济，信息经济的时代。随着数字技术的飞速发展，卫星广播电视技术也得到巨大的飞跃。电视台根据技术发展和卫星覆盖范围调整的需要，经常要对发射的卫星电视节目的传播与接收方式进行调整。     

校园电视系统的设计、安装和调试

校园电视系统是以卫星电视节目、有线电视节目和自办教学节目为主体,实现卫星电视节目和自办教学节目插入本地有线电视的闲置频段,再混合后传输给用户。卫星电视节目的接收、安装和调试,自办节目的混合传输是整个系统的关键。     

新技术 新设备 新产品

航天工业部第504研究所据市场需要,充分发挥军工技术优势,研制出一种可使电视用户直接接收到卫星电视节目的XRCF——40A型同轴波导馈源系统,日前获得国家专利。 随着卫星广播通讯事业的发展,我国卫星电视接收,将从过去的集体接收时代,逐步向个体接收时代转变,逐步告别过去各地区接收卫星电视节目,必须通过较大型的卫星电视接收站,再将收到的节目进行频率变换,功率放大后,通过电视台、差转或公用天线、闭路电视转到各用户。504所研制出的XRCF——40型同     

“卫星电视多媒体接收系统”课题通过鉴定

20 0 0年 1月 2 7日 ,由山东省教育厅主持 ,在山东师范大学召开了“卫星电视多媒体接收系统”技术鉴定会 .鉴定委员会听取了课题组的研制工作报告、研制技术报告、查新咨询报告、经济效益社会效益分析报告和用户使用报告 .详细审查了鉴定资料 ,进行了现场测试 ,并观看了实际接收效果 .经过认真讨论 ,鉴定委员会专家一致认为 :1)卫星电视多媒体接收系统各项指标均达到计划任务书所规定的技术规格和使用要求 .2 )提供的技术资料翔实、齐全、完整 ,符合技术鉴定要求 .3)对接收鑫诺一号卫星传输的中国现代远程教育节目信号进行了系统链路分析和…     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has