膜材厚度偏差对充气天线反射面精度的影响

以非线性有限元逆迭代法为基础,研究膜材厚度偏差对充气天线反射面成形精度的影响。分析均匀分布及线性非均匀分布两种典型的膜材厚度偏差分布形式对充气天线反射面的影响规律和敏感度,并考虑不同充气天线反射面焦径比F/D的影响。结果表明:形面误差的分布规律与膜材厚度偏差分布形式相关;偏差均匀分布比线性非均匀分布对精度影响更大;F/D越大,厚度偏差引起的反射面形面误差越大。     

反射面变形对天线辐射特性的影响

研究在冲击波作用下,赋形双弯曲反射面变形对天线辐射特性的影响.利用物理光学法对双弯曲反射面雷达天线的辐射方向性进行了建模和分析,将反射面完好时的计算结果与测试结果进行比较,其结果较为一致.在此基础上,重点研究了天线反射面变形后天线辐射特性随变形量、变形位置和变形面积的变化.计算结果表明,反射面的变形对水平面方向图影响较大,对垂直面方向图的影响很小.     

桁架式可展开天线反射面精度试验

为了验证一种桁架式可展开天线结构设计方法的正确性,制作了一个口径为2 m的天线模型,设计了由上部中心立柱加三支杆悬挂支撑天线的试验悬挂方案,用基于PhotoModeler软件建立的摄像测量系统对天线抛物面反射面进行精度测量,将测量数据带入基于浅壳理论推导出的精度计算方程计算反射面误差.模型的反射面精度与设计值接近,表明该结构设计方法适合于设计更大口径的该类型天线.设计制作了6 m×2.8 m口径的天线,并对此天线进行了两种姿态下的展开精度试验,精度测量结果表明反射面精度符合设计要求.     

基于微扰法的低驻波比反射面天线设计

介绍并分析了用于反射面天线低驻波比的微扰设计方法,并基于该方法设计了一Ka波段低驻波比的反射面天线.通过对天线反射面外形的微扰设计,该反射面天线在保持辐射性能基本不变的条件下,天线驻波比得到了显著降低.     

变形双反射面天线的机电耦合分析方法

双反射面天线广泛应用于雷达、卫星通信和射电天文等领域,针对变形双反射面天线的电性能求解问题,本文提出了基于物理光学法的机电耦合分析方法.深入分析了双反射面天线主副反射面变形对天线电性能的影响,通过将主副反射面轴向变形转换为天线远场积分公式中的相位误差影响项,建立了反射面表面结构位移场与天线远场之间的机电耦合关系.进一步将相位误差影响项作一阶泰勒级数展开,使得结构误差从天线远场积分运算中独立出来,通过构建包含主副反射面变形信息的误差矩阵可实现变形反射面天线远场的快速计算.对一个2.2 m天线进行案例分析,结果验证了所提方法的正确性.     

球形陆基充气天线反射面初始形态的确定

利用有限元软件ANSYS及其参数化语言APDL建立了球形陆基充气天线反射面模型.结合抛物面的边界及受力特点对模型进行了逆迭代分析,得到了天线反射面的初始形态.分析结果表明,逆迭代法效率较高,经过少量迭代次数便可得到精度较高的初始形面.     

抛物面天线反射面参数化建模与热变形优化分析

为更好地分析卫星在轨运行期间天线主反射面热变形对天线性能的影响,应用PCL,对MSC.PATRAN/NASTRAN进行二次开发,将参数化建模、抛物面拟合、型面精度分析引入有限元计算,并对某大口径复合材料天线主反射面在均匀温度场下的热变形进行了数值模拟,优选出合理的铺层方式,获得了变形后的天线性能指标.研究结果表明:数值模拟探索出适合于在轨卫星天线减少热变形的铺层设计方法,所获变形值、抛物面拟合参数、型面精度误差等结果符合设计要求,为复合材料天线主反射面的设计应用提供了依据,同时解决了通用CAE软件无法预估热变形对天线性能影响的问题.      

卫星通信伞天线抗风荷结构的研究

伞结构天线具有折叠和便携的特点,可用来替代抛物面天线。抗风荷设计是伞天线研究的关键。文中分析了伞天线反射面内外表面承受风阻的情况,设计出一种抗风荷结构,即在伞形天线的每个三角形曲面的局部区域利用双层无缝铜网代替银纤维布,以及采用三角体结构同时支撑主机和反射面天线的结构形式,大大提高了抗风荷能力。     

高效偏置反射面天线

分析了带交叉接头的双模馈源，分析了计算了收，发状态下偏置反射面天线的辐射场和焦区场，讨论了馈源位置误差，设计和测试了高效偏置反射面天线，实测结果与预计结果一致，达到预期的高效率，该天线适用于卫星电视接收站。     

基于电气柜门体折弯模具的设计

本文叙述了一种电气柜门体折弯模具的设计计算方法,简单实用,方便可靠。根据零件的加工工艺分析以及加工零件的精度要求,选择合适的加工材料和工艺方法,完成模具的结构设计,并对模具关键零部件进行计算校核。针对折弯模具的设计,本文提供了一个清晰的思路和简单的方法,模具设计过程得到了了更进一步的阐述。     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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