用于35mm电影放映机的一种新型镜头

由7个非胶合元件组成的一种新型镜头系统已经研制出来。这种新型镜头的焦距为75mm,相对孔径为 f/1.4,用于35mm 电影放映机的物镜上。为了比较该镜头系统的性能,以双高斯型镜头为基础,采用通常的设计方法,研制了一种由7个非胶合元件组成的系统。这种镜头的性能通过绘制象差曲线、能量分布曲线和几何 MTF 曲线进行了评定。这种新型镜头的性能优于目前使用的双高斯型镜头。     

优化整合电影资源 服务物理课堂教学

以电影为独特视角,把非课程资源改造成课程资源,给物理课堂注入新的亮点.     

一种高智能化的通用自动胶片判读仪

自动通用胶片判读仪是一种高智能化的精密光学测试设备,采用了计算机控制飞点扫描技术、精密光学测量技术、图象跟踪测量与信息处理技术。飞点管分辨率达4096×4096象元,通过光学系统胶片上获得6.55μm高分辨率,飞点扫描方式灵活多样且可随意控制,通用于目前我国靶场所有的电影经纬仪和高速摄影机35mm胶片的数据判读。具有自动判读和半自动判读两种工作模式,自动判读的速度为5帧/秒,自动判读的精度为σ=±0.011mm,半自动判读的精度为σ=±0.009mm,测量数据可以记录、打印和显示。     

基于COLLATE融合多图谱的心脏电影MRI右心室分割

右心室分割对肺动脉高压等疾病的心功能分析具有重要的临床意义.然而，右心室心肌薄、易变且不规则，其传统的医学图像分割方法仍然未能取得突破性进展.本文提出基于COLLATE（Consensus Level，Labeler Accuracy and Truth Estimation）的多图谱分割方法，首先以归一化互信息为相似测度对目标图像和图谱集进行B样条配准以获取粗分割结果；然后利用COLLATE对粗分割结果进行融合；最后采用基于形状约束的区域生长算法修正出现错误的数据.10例临床心脏磁共振短轴电影图像被用于算法验证.本文还将使用基于COLLATE的多图谱分割方法得到的结果与深度学习算法及手动分割进行了比较.结果显示与深度学习算法比较，使用本文算法得到的射血分数（Ejection Fraction，EF）与手动分割更加一致和相关，表明该算法的分割结果有望辅助临床心脏功能诊断.     

结合生物力学模型重建左心室位移场

左心室心肌最为发达,心肌收缩产生的高压将动脉血泵入全身,集中体现了心脏的泵血能力.定量分析左心室收缩运动是诊断心血管疾病（如心肌梗死）的重要途径.本文采用描述左心室心肌材质的生物力学模型重建左心室位移场.该力学模型作为插值项,与心脏电影磁共振图像的观测位移场共同纳入贝叶斯估计框架,并采用有限元法求解位移场方程.实验比较了左心室射血无力组（46例）与正常组（55例）的左心室功能参数,发现两组在径向和圆周方向的位移、速度、应变和应变率都具有非常显著的差异（p < 0.001）,这证明本文方法能够有效区别左心室运动正常与否.实验结果还与CVI软件测量的左心室功能参数具有较高的相关性,说明本文方法有望辅助心血管疾病的临床诊断.     

超紧凑型飞秒电子衍射仪的设计

由于空间电荷效应的限制,产生百飞秒的极短电子脉冲是超快电子衍射技术的一大难点.同时,电子的穿透深度随着电子能量的增加而增加,而电子的散射几率却具有相反的规律.因而,除了时间分辨的提升,还需要可宽范围调节的电子能量以优化不同厚度样品对其的需求.基于此,提出并设计了一种新型超紧凑电子枪,结合均匀场阴极和可移动阳极的配置,可在10-125 kV加速电压范围内实现100 fs量级时间分辨率.通过优化设计高压电极轮廓,使得其轴上和整个阴极面的场增强因子在不同阴阳极间距下均小于约4%,从而保证了不同加速电压下最大轴上场强均可达10 MV/m量级,有效地抑制了电子脉冲的展宽效应;进一步将阳极小孔设计成可放置致密电镜载网的阶梯孔,一方面可将载网支撑的样品紧贴小孔后方放置,最大程度上缩短了电子从阴极到样品的时间弥散,同时也可以有效地减弱阳极孔对电子束的散焦效应,提升电子束的横向聚焦性能.     

电影音乐录音中的电平控制

声音信号的重要计量值为 VU 值和峰值,它们分别直观反映声音强度及失真情况。为了透彻分析和阐述电影音乐节目制作系统的特性,该文通过实验的方法,测量了大量乐器在典型演奏法下的 VU值和峰值。进而通过实验数据的结果,做出 P/VU概率分布曲线。各音乐信号的 P/VU分布情况决定了系统的电平储备,掌握此结论非常有助于进行电影音乐节目制作过程中的电平控制。     

高相干超快电子源研究进展

以原子级时空分辨监测物质的动力学行为并从最根本层面理解自然界中的微观基本过程一直是飞秒物理、飞秒化学以及飞秒生物学研究的目标.时间分辨电子衍射巧妙地结合了抽运-探测技术和电子衍射技术,可实现直接"观察"和"冻结"类似的超快过程.然而,目前常用的超快电子探针的横向相干性仍受到电子源的初始尺寸、有效温度、能量弥散以及电子间固有库仑排斥的限制,还很难分辨化学和生物相关的复杂有机分子.近年来大量研究工作都集中在发展高相干的超短电子源,其不仅对时间分辨电子衍射研究起到推动作用,也将极大地促进超快电子显微镜、相干衍射成像以及叠层成像等的发展.本综述以相干性为主线,介绍了几种常用平面阴极光电发射源的研究进展,并从产生机理、独有特性和实验成果方面讨论了尖端发射源和冷原子电子源这两类新型的高相干超快电子源,最后对衍射技术的相干性发展和未来应用进行了展望.     

短焦段数字电影变焦放映镜头的设计

为了填补国内短焦段数字电影变焦放映镜头的空白及满足国内数字电影市场对大投射比镜头的需求,本文采用机械补偿式变焦原理,利用ZEMAX光学设计软件自主研发设计出一款适用于0.65英寸、单数字光处理器、1.3K数字电影放映机的短焦段连续变焦数字电影放映镜头.镜头包括前固定组、变倍组、补偿组和后固定组,由8组10片玻璃球面透镜组成,其中变倍组由一片负透镜构成,补偿组由两组双胶合透镜组构成.镜头总长170mm,全口径70mm,变焦范围为14.5～18.2mm,相对孔径为1/2,投射比范围为0.99∶1～1.23∶1,后工作距离为32.6mm.镜头凸轮曲线的设计采用等间隔变焦的方法,设计出了平滑稳定、斜率适宜、压力角小的凸轮曲线,具有加工方便、加工准确度高、变倍组升角容易控制且焦距变化均匀的优点.整个镜头结构简单、体形小、重量轻、成本低.     

2893年2月2日:爱迪生在影片中记录第一个〝喷嚏〞

每个周末都有数百万人成群结队地进入戏院观赏最新上映的好莱坞巨片，但很少有人会去思考我们现在习以为常的娱乐业之科技根源。虽然在19世纪后期，有许多科学家和发明家做了电影的实验，但只有著名的美国发明家爱迪生利用他最早发明的电影照相机（他称之为电影摄影机）制作短的影片，由他同时发明的“电影放映机”播放出来，取得了专利。     

基于心脏磁共振短轴电影图像的右心室分割新进展

右心室分割对肺动脉高压、法洛四联症等疾病的心脏功能评估具有重要意义.然而，右心室结构复杂，变动性大、心肌薄且毗邻脂肪，实验全自动分割一直是难点.心脏磁共振短轴电影图像时空分辨高，常用于临床右心室分割及功能评价.本文基于心脏磁共振短轴电影图像对右心室分割方法进行了综述，首先回顾了传统右心室分割算法，然后重点介绍了基于多图谱和深度学习算法的右心室分割进展，并介绍了右心室分割结果常用的评估指标.通过上述回顾发现，基于深度学习算法的分割方法是今后临床应用的右心室分割的主要方法，对心脏相关疾病的诊断及预后十分重要，而且可大大提高医生的工作效率.     

基于心脏磁共振电影图像的压缩激励残差U形网络左心肌分割

左心肌分割对心脏疾病诊疗具有重要意义.但左心肌内部毗邻乳头肌、小梁,外部与周围组织灰度相近,是分割难点.本文首先对心脏磁共振电影图像数据进行感兴趣区域提取等预处理;其次,搭建融合了压缩激励模块和残差模块的U形网络(SERU-net)分割左心肌;最后,利用75例数据训练SERU-net网络,对18例数据进行预测.基于本文方法的分割结果相对于金标准的Dice系数与豪斯多夫距离均值分别是0.902、2.697 mm;利用本文方法分割得到的舒张末期、收缩末期左心室心肌质量与金标准的相关系数和偏差均值分别是0.995、0.993和3.784 g、2.338 g.结果表明,本文方法与金标准匹配程度较高,有望辅助诊断心脏疾病.     

Demagnetizing factors in patterned CoNiFe films with rectangular elements

CoNiFe patterned films with rectangular elements, all 600-nm wide but of different lengths, were fabricated and investigated by ferromagnetic resonance experiment and micromagnetic simulation. An in-plane magnetic uniaxial anisotropy was exhibited, and its value increases with the increase of the aspect ratio of the elements, which was fitted by the model, including a quasi-ellipsoid demagnetizing field and a non-uniform demagnetizing field. The relative importance of the nonuniform demagnetizing field decreased from 0.26 to 0.16 with the increase of the length-width aspect ratio of the patterned element from 1.5 to 10. The demagnetizing factors in the three principal axes were determined from the experimental data of ferromagnetic resonance, which agreed reasonably well with the values calculated by micromagnetic simulation. The calculation also indicated that the interaction between elements could be neglected when the edge-to-edge spacing between neighboring elements was larger than 3 μm in our patterned films.     

Transition to Film Boiling in Microgravity： Influence of Subcooling

The transition process to film pool boiling in microgravity is studied experimentally aboard the Chinese recoverable satellite S J-8. A quasi-steady heating method is adopted, in which the heating voltage is controlled to increase exponentially with time. Small, primary bubbles are formed and slid on the surface, which coalesce with each other to form a large coalesced bubble. Two ways are observed for the transition from nucleate to film boiling at different subcoolings. At high subcooling, the coalesced bubble with a smooth surface grows slowly. It is then difficult for the coalesced bubble to cover the whole heater surface, resulting in a special region of transition boiling in which nucleate boiling and local dry areas can coexist. In contrast, strong oscillation of the coalesced bubble surface at low subcooling may cause rewetting of local dry areas and activation of more nucleate sites, resulting in an abrupt transition to film boiling.     

Direct Observation of High-Temperature Superconductivity in One-Unit-Cell FeSe Films

We prepared one-unit-ceil （1-UC） thick FeSe films on insulating SrTiOa substrates with non-superconducting FeTe protection layers by molecular beam epitaxy for ex situ studies. By direct transport and magnetic measurements, we provide definitive evidence for high temperature superconductivity in the 1-UC FeSe films with an onset Tc above 40 K and an extremely large critical current density fie Jc-1.7× 106 A/cm2 at 2K, which are much higher than Tc-8K and Jc-104 A/cm^2 for bulk FeSe, respectively. Our work may pave the way to enhancing and tailoring superconductivity by interface engineering.     

Characteristics of the crystalline and luminescence properties of a-plane GaN films grown on γ-LiAlO2 （302） substrates

A method of clarifying bioaerosol particles is proposed based on T-matrix. Size and shape characterizations are simultaneously acquired for individual bioaerosol particles by analyzing the spatial distribution of scattered light. The particle size can be determined according to the scattering intensity,while shape information can be obtained through asymmetry factor(AF) . The azimuthal distribution of the scattered light for spherical particles is symmetrical,whereas it is asymmetrical for non-spherical ones,and the asymmetry becomes intense with increasing asphericity. The calculated results denote that the 5 –10 scattering angle is an effective range to classify the bioaerosol particles that we are concerned of. The method is very useful in real-time environmental monitoring of particle sizes and shapes.     

Bipolar resistive switching in BiFe_(0.95)Zn_(0.05)O_3 films

Bipolar resistive switching is studied in BiFe0.95Zn0.05O3 films prepared by pulsed laser deposition on （001） SrTiO3 substrate, with LaNiO3 as the bottom electrode, and Pt as the top electrode. Multiple steps of resistance change are ob- served in the resistive switching process with a slow voltage sweep, indicating the formation/rupture of multiple conductive filaments. A resistive ratio of the high resistance state （HRS） to the low resistance state （LRS） of over three orders of mag- nitude is observed. Furthermore, the conduction mechanism is confirmed to be space-charge-limited conduction with the Schottky emission at the interface with the top Pt electrodes in the HRS, and Ohmic in the LRS. Impedance spectroscopy demonstrates a conductive ferroelectric/interfacial dielectric 2-layer structure, and the formation/rupture of the conductive filaments mainly occurs at the interfacial dielectric layer close to the top Pt electrodes.     

新型光纤让看3D电影不戴眼镜

麻省理工学院的电气工程师和材料科学家近日制造出一种神奇的光纤，用其编织成的柔性显示屏可以播放3D图像而观众不必佩戴特制眼镜来观看。该研究近期发表在《自然-光子学》网站上。     

Preparing Cu2ZnSnS4 films using the co-electro-deposition method with ionic liquids

Cu2ZnSnS4（CZTS） films are successfully prepared by co-electrodeposition in aqueous ionic solution and sulfurized in elemental sulfur vapor ambient at 400 C for 30 min using nitrogen as the protective gas.It is found that the CZTS film synthesized at Cu/（Zn＋Sn）=0.71 has a kesterite structure,a bandgap of about 1.51 eV,and an absorption coefficient of the order of 10 4 cm 1.This indicates that the co-electrodeposition method with aqueous ionic solution is a viable process for the growth of CZTS films for application in photovoltaic devices.