Tomographic inversion of ocean bottom seismograph (OBS) data: Problems and solutions applied to the NW Svalbard Hydratech data set

The paper is aimed at discussing some problems that may arise in the tomographic inversion of data acquired with particular geometries, as vertical seismic profiles (VSP) or implying the use of Ocean Bottom Seismographs (OBS), and presenting the solutions used to solve them. One problem is due to the limited number of sensors (that may be even a single one) and of their sparseness. This affects the information distribution that is concentrated in the vicinity of each sensor. This fact, together with the second problem, i.e. the strong asymmetry of the ray path, may decrease the reliability of the inversion.Two procedures for irregular adaptive gridding of the reflecting interfaces and single ray datuming are proposed as possible solutions to overcome these obstacles, while obtaining a reliable and highly resolved velocity model in depth: the relative procedures are tested through synthetic models and on real data.     

考虑太阳照射的地基面天线机电耦合分析

下一代深空探测的地基面天线的面精度要求达到亚毫米级,必须考虑太阳照射导致的温度的影响。针对这一问题,以"嫦娥工程"的40 m通信面天线为研究对象,根据天线的地理位置和时间日期,计算天线受到的热流密度;考虑对流、传导和辐射三种传热方式计算天线的温度分布,并用某7.3 m卡式天线设计温度试验,结果表明温度分析是有效的;将温度作为载荷计算天线的结构变形;根据天线远区的电场公式计算电性能,并提取增益损失、副瓣电平和指向误差等主要电性能指标。仿真结果表明,温度对电性能的影响不但体现在结构变形的均方根值上,更与变形的分布形式密切相关。分析的方法和结论可用于指导下一代面天线结构设计,也可供同类型面天线设计时参考。     

尾灯壳体流道尺寸及注塑参数优化

对某型号轿车尾灯壳体结构进行了分析,全流程跟踪了主要外观面、次要外观面、典型定位扣接特征、雾灯反射镜、位置灯反射镜的制造过程。利用正交试验法及极差分析法,对主流道形状及尺寸、冷流道形状及尺寸、冷浇口形状及尺寸、注塑初始温度,进行了研究。得出,模具主流道小端直径取Φ6.5 mm,锥度取0.5°;冷流道直径取Φ7.5 mm;冷浇口设置成方形浇口,尺寸2.0 mm×6.0 mm;注塑初始温度取205℃时,在H1I4J1K2组参数下,翘曲量更低,为0.9180 mm。通过试验验证,所得制品各扣接特征,功能完整;主要外观面,表面光洁;雾灯反射镜,没有缩瘪现象;位置灯反射镜,轮廓饱满。     

宽角扫描偏置单反射面天线的面赋形设计

为实现宽角扫描,对偏置单反射面天线进行了面赋形设计,减少了天线在扫描过程中所需馈源阵单元的数目,或者说在馈源阵单元数目给定的情况下,赋形工作降低了波束扫描给天线带来的增益损失.赋形工作中,首先根据反射面的初始数据,以双三次B样条函数逼近其初始形状,然后从各预定的馈源位置向反射面发出若干条射线,并采用几何光学(GO)求得这些射线经反射面反射后的方向,最后以这些反射线的方向与各对应扫描方向之间的偏差最小为优化目标,通过Poweu方法对样条函数的插值数据点进行调节,最终确定了赋形反射面的形状.模拟结果表明了文中所述方法的可行性和有效性.     

Pre-dried refiner flakes allow very short or even continuous conching of milk chocolate

Chocolate conching is usually still performed in a time consuming batch process. For milk chocolate, its main purpose is to remove water and to adjust flow properties. As the conch is not an efficient dryer and flow properties are mainly influenced by shear treatment, the objective of this study was to separate and optimise both processes. Prior to liquefaction, refiner flakes were dried to <0.6% of water in an oven, which allows to omit the dry phase of conching. Conventional conching of 5 h was then reduced to a liquefaction process taking 20 min. Alternatively, continuous processing was tested applying a high shear mixer REFLECTOR^®. Sample properties were very close to a standard. Only continuous liquefaction at very high throughput resulted in slightly increased viscosity. Sensory analyses just found negligible differences. Thus neither pre-drying nor short or continuous liquefaction had a negative impact on product quality.     

低能粒子辐照对铝膜反射镜光学性能的影响

地面模拟研究了低能质子和电子对铝膜反射镜光学性能的影响。结果表明,低能质子辐照后,在200~800nm波长范围内铝膜反射镜反射率随辐照剂量增加而下降。质子辐照能量越低射程越短,则反射镜表面膜层中质子浓度越大损伤也更为明显。电子辐照射程较深,辐照作用对铝膜反射镜光学性能影响很小。     

VCSEL技术及其在光互连中的应用

垂直腔表面发射激光器（VCSELs）是并行光互连、高速光交换系统中最合适的光源。它具有易耦合、易封装和测试的优点。由于其独特的性能，可以较为方便地制作二维激光器阵列。基于VCSEL阵列的光电混合集成及并行光互连是当前的研究热点。本文介绍了VCSEL基本结构及设计中的关键技术，并对VCSEL在光互连中的应用进行了研究。     

角锥棱镜的误差分析

本文根据光的矢量形式的反射定律,导出了角锥棱镜的出射光线偏角误差与角度误差的关系式,讨论了三种特殊情况下的出射光线偏角误差,并对各反射面和折射面面形误差对出射光束的影响进行了分析计算,所得结论可为角锥棱镜角度公差及面形误差的给定提供理论依据。     

等离子体反射面天线性能参数仿真

采用FDTD仿真软件对等离子体反射面天线的近场场强分布及远场辐射方向图进行了研究。由仿真所得的方向图导出了不同等离子体密度下5.8G微波的反射率,结果表明电磁波在等离子体中的穿透深度会对反射率造成影响。研究发现这种影响对于频率较低的电磁波更加明显。     

基于VC与MATLAB的全景视觉反射镜设计

介绍了Visual C 和Matlab的特点及其在数学计算、图形显示方面的优势,在分析了全景视觉系统反射镜设计原理的基础上,首次提出应用VC和Matlab混合编程方法实现反射镜设计.该方法实现了反射镜设计的自动化及可视化,最后介绍了设计实例,实践证明该方法显著提高了系统设计的效率.