一种小型化多频接收天线的研制

设计、分析和制作了一种小型化多频段圆极化微带天线,天线能够同时工作在北斗系统B1频段、S频段以及GPS L1频段。通过采用叠层、介质加载、蚀刻不连续缝隙和耦合馈电等方法,实现了天线的小型化设计制作,保证了天线结构的简单紧凑。测试结果表明,该天线具有较高的增益和良好的电性能,并且天线尺寸仅0.28λ×0.28λ×0.02λ(λ为L1频率处对应的波长),从而证实了该方法的正确性和实用性。本文所设计的小型化多频圆极化接收天线由于具有剖面低、结构简单紧凑、易于集成安装等优点,在航空、航天领域中具有很好的应用前景。     

电性能仿真平台及其在大型面天线机械结构设计中应用

大型面天线在工程中有着广泛应用,其机械设计与电气设计是分开进行的。天线结构设计人员由于不了解电磁理论,只能依靠经验设计天线机械结构,来保证天线满足电气设计人员提出的精度指标。结果是生产周期很长,成本浪费严重。因此,有必要建立天线电性能仿真平台。在设计天线虚拟电子样机之后,通过该平台来计算天线电性能,判断天线结构是否满足要求。工程中应用此平台,将使结构设计人员提高天线设计与制造效率,减少次品率,降低天线设计与制造的成本。     

太赫兹冰云成像仪结构设计及耦合分析

太赫兹频段的微波探测仪对冰云的有效探测将极大地促进全球和局部气候研究,但成像仪内部空间狭小,结构设计难度较大,且单机布局紧凑、功耗较大,太空环境与太阳直照会使天线反射面结构变形,从而影响载荷电性能。文中对成像仪系统进行了详细的结构设计,运用有限元软件验证其在各试验工况下的力学特性,并对载荷温度进行在轨计算,将温度数据映射到模型中进行热变形计算,将结构热变形数据代入Grasp系统仿真。通过耦合分析,评估天馈系统结构热变形对其电性能的影响,结果表明电性能指标均满足设计要求。     

太赫兹天线结构设计

太赫兹天线工作频率高(100 GHz~10 THz),加工、装配精度要求严苛,合理有效的天线结构设计是太赫兹天线工程化亟待解决的技术难题之一。文中研制了一套工作在0.33 THz的太赫兹天线,详细阐述了天线结构、各组成结构材料和互联以及天线装配,并根据使用环境,对天线结构进行了仿真和电性能测试。结果表明,整套天线满足刚强度等各项指标要求,也验证了该天线结构设计的合理性和有效性。     

某弹载雷达天线系统结构设计

针对弹载雷达轻小型化的特点,提出一种天线系统的结构设计方法。重点介绍天线系统的结构组成、主要零部件的结构设计以及热设计等,对类似天线系统的结构设计具有一定的借鉴意义。     

某车载偏馈天线结构设计

随着人类社会的进步和时代的发展,市场竞争日益激烈,高性能、低成本、轻量化和小型化的天线研发越来越受关注,能否研发出性价比高的天线关系到企业的生存发展。文中以车载偏馈抛物面天线为例,分析其结构设计需求,根据其结构特点,并结合工艺、装配、运输和成本等方面的要求,设计了一种低风阻、低成本、高性能的轻薄型天线。对天线的主要部件,比如反射面、天线骨架和调整装置的结构设计做了详细叙述。通过有限元分析软件对该天线进行力学仿真分析,得到了天线结构在工作状态下的应力云图和变形云图。计算结果表明,该天线结构整体性能较好,满足刚强度设计要求,验证了其结构设计的合理性。     

某星载反射面天线结构设计

反射面天线结构是天线电气性能实现的载体和保障。文中详细阐述了某星载反射面天线的结构设计要点,重点论述了碳纤维复合材料反射面的具体结构形式和反射面及背筋的详细结构设计。建立了天线的有限元模型,进行了模态分析、正弦振动仿真分析、热变形分析。仿真分析和振动试验结果表明：该天线有足够的刚强度,满足设计要求。研究结果可以为星载反射面天线结构设计提供工程参考。     

基于粒子群算法的RFID天线优化设计

本文设计了一款中心频率是2.45GHz的微波频段标签天线,通过对天线的弯折处理,实现标签天线的小型化;利用HFSSMATLAB-API接口程序,实现了HFSS软件和MATLAB软件的联调,采用粒子群算法对天线进行优化,最终得出了天线的最优尺寸。     

一种测控天线支架的优化设计

在航天领域,星上载荷的质量直接影响整星的发射成本。为了降低星上天线的质量,文中以某卫星测控天线支架为研究对象,在满足天线电性能和力学性能的前提下,采用传统方法和拓扑优化分别对支架进行改进设计,然后利用有限元分析软件Workbench对天线进行仿真分析,得到模态响应曲线和正弦振动应力云图,并对比分析仿真结果,获得支架的最优结构设计方案。该支架通过拓扑优化设计并采用增材制造（3D打印）技术加工,不仅满足各项性能指标要求,而且其质量降低了20.3%,加工时间也缩短了近60%。     

球形偶极子辐射天线小型化的仿真设计

针对工程中机箱机柜屏蔽效能测试系统中宽带天线的特性要求,必须使用宽频带且尺寸小的测试天线。球形偶极子辐射天线作为一种新型的宽频带有源天线,兼备了信号处理功能,使天线小型化与宽频带成为可能。采用HFSS电磁场仿真软件建立有源球形偶极子辐射天线模型,并对其尺寸进行优化。使用MATLAB软件制图对比分析天线的理想尺寸为80mm左右以及小型化后对天线性能的影响。同时在理想尺寸下,使天线覆盖30MHz-1GHz频段,通过将双锥以及螺形结构与球体相结合等方法改善天线结构,解决了天线小型化后低频增益偏低的问题。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.