基于形状插值的B超图像三维表面重建

B超图像由于受其成像机理的限制,其成像质量较差,无法采用与CT(计算机断层扫描)、MRI(磁共振成像)类似的三维重建方法。针对B超图像的缺点,采用基于形状的插值方法将其转换为等分辨率体数据。此外,对插值算法进行了适当改进,使重建的速度和效果得到明显改善。最后,分别采用移动立方体(marching cubes)算法、连接轮廓线、光线投射(ray casting)算法对B超图像进行三维重建。结果表明,移动立方体算法在重建的真实性和快速性方面都得到了更满意的效果。     

海洋大气近地层折射指数模式及其在蒸发波导分析上的应用

利用Ｍｏｎｉｎ－Ｏｂｕｋｈｏｖ相似理论给出了不同大气结条件下海洋大气近地层折射指数模式，并利用这些模式分析了蒸发波导内可能存在的波导模，给出了确定蒸发波导所能捕获最大电磁波波长及相应最低频率的计算式并对其在不同大气层结条件下的计算结果进行了比较，发现在不稳定、中性和近中性层结条件下，其计算结果比较接近，但在强稳定层结条件下，差异显著，最后给出了射线追踪方程，并通过用多层线性模式来近似蒸发波导内大气     

Prism coupling method to evaluate the light extraction efficiency of outcoupling substrates

One of the key challenges in organic light-emitting diodes (OLEDs) for lighting applications is efficient light extraction from the planar, multi-layered OLED stack. Several different light extraction approaches are being explored currently by researchers, however characterizing light extraction films after fabricating OLEDs is not a viable approach when the outcoupling films have large surface roughness and is time consuming as well. Here we apply prism coupling method (PCM), a simple and elegant tool, to characterize outcoupling films. We show the effectiveness of PCM in estimating light extraction efficiency of outcoupling films. PCM can expedite selection and optimization of various light extraction approaches without the need to build OLEDs. The experimental results are corroborated by the optical simulations done using ray tracing method taking into account Mie scattering from wavelength sized spherical inclusions in an outcoupling film.     

雷达舱和天线罩的电磁散射

在目标散射问题中,雷达舱和天线罩的散射机理有极大相似之处。在该类散射问题中,电磁波进入腔体时首先在整流罩上进行反射和折射,电磁射线进入雷达舱和天线罩后入射于天线上,天线反馈电磁射线,电磁射线透过介质罩形成了散射电磁波。对射线入射于非金属目标的轨迹分裂提出了更为精细的解决方法,并用射线方法计算了该类目标的雷达散射截面。     

The Reception and Sources of Berenice Abbott's Paris Portrait Style, 1925–1929

This study focuses on the photographs that first brought Berenice Abbott critical acclaim: her Paris portraits from the late 1920s. As a body of work, these images – along with what Abbott had to say about them and the critical attention they generated at the time – provide a rich resource for the study of three interconnected topics: the avant-garde critical climate of Europe in the late 1920s, the American expatriate experience in Paris during this same time and Abbott's nascent photographic values and aesthetic, which helped to inform not only her portraits but also her later, better-known photographs of New York City. The paper first defines the divergent critical responses to Abbott's portrait work in the late 1920s – focusing especially on the published criticism by Florent Fels and Pierre Mac Orlan that helped to secure Abbott's international reputation as a leading modern photographer. It then turns to Abbott's expatriate experience in order to examine the ideas and individuals that she identified as most important to her photographic practice. Specifically the paper explains Abbott's desire to create an alternative approach to photography from the one used by Man Ray, her awareness of the classical style associated with Pablo Picasso and her admiration for the aesthetic theories of Leo Stein.     

表面状态对轿车用新型齿轮钢疲劳寿命的影响

较详细地研究了表面应力状态和表面光洁度等对汽车用齿轮的疲劳寿命的影响规律。实验发现,随着喷丸形成的表面应力增大,齿轮疲劳寿命显著增加,而且表面光洁度的改善也能明显提高齿轮的疲劳寿命。     

染整工艺应用远红外加热技术的研究(Ⅱ)

上期刊登的内容为远红外加热技术应用于染整加工的意义及推广应用的关键,在于运用好远红外辐射加热技术三原则即最佳光谱匹配、定向集中辐射和最佳综合效益,并论证了最佳光谱匹配原则。     

反应过程中升华型催化剂的物性变化(Ⅱ) X—射线衍射结果

对衰化程度不同的升华型催化剂进行了 X—射线衍射测定。发现在使用过程中催化剂比表面迅速减小,但氯化汞-活性炭催化剂的新旧样品中,氯化汞均保持单层分散。但即将废弃的醋酸锌-活性炭催化剂上,醋酸锌的单层分散情况受到破坏,出现了醋酸锌晶相峰。晶相峰的出现可能与后期使用温度偏高引起烧结有关。晶相峰的出现会降低催化活性,使之不得不被废弃。     

铸件缩孔与缩松的图像模拟

为了直观地显示铸件缩机与缩松的数值计算结果,设计了1种称之为仿X－Ray探测效果的显示技术。采用该技术来显示铸件的缩孔、缩松,可以达到类似X－Ray无损探伤的效果,提供给用户1幅透明的铸件模型图象使缩孔、缩松的位置一目了然。该技术已成功地应用于BUAA－CAST铸造过程仿真系统中。     

基于多源异构数据融合与RT的高铁网络优化系统

在高速铁路建设中,采用的电力拖车、路堑、站台、桥梁、明洞等特殊、形状不规则的建筑物,会对电磁波传播机理和多通路产生一定的影响,使其呈现出明显的衰减特性。从空间上看,呈现出强烈的空间异同性和频度相关,从而导致经验模型无法准确表征铁路场景的电波传播特性,成为制约无线网络规划精确度与效率、限制铁路移动通信系统高质量发展的理论瓶颈之一。针对这一挑战性难题,本文开展了基于多源异构数据融合的铁路移动通信高精确度网络规划及优化系统研究。采用高性能射线跟踪(RT)技术针对铁路通信930 MHz频段下的高铁场景进行了网络优化仿真。仿真结果表明,90%的接收信号强度相较于优化前提高了13.9 dB,显著提升了铁路复杂场景中的无线网络质量。