战斗部破片速度光幕靶测量方法研究

针对战斗部常规生产检验,提出了采用多个光幕靶、数据采集仪和位置标识器进行测速的方法。光幕靶探测破片穿过的时刻,数据采集仪记录波形并提取破片穿过光幕靶的时间,位置标识器可以识别破片飞行的方向角度,从而计算破片实际飞行的靶距。介绍了测速系统的组成,光幕靶设计以及测速系统的冲击与破片杀伤防护措施。采用战斗部静爆试验验证了所提方法,结果表明所提方法准确有效。给出了破片穿过光幕的瞬态波形。     

A computer model for predicting sound attenuation by barrier-buildings

This paper describes a computer technique involving a procedure for finding the performance values within the shadow zone of a barrier-building of rectangular cross-section used as a point source. Reflections from the ground are also taken into account and a control operation is designed for different source and receiver locations related to the building. Consideration is given to the combined effects of wide barriers and finite size screens. The results are confirmed by several experimental measurements carried out in an anechoic room. Some examples of the application of the technique are given.     

Plasmonic Brewster angle: broadband extraordinary transmission through optical gratings

Extraordinary optical transmission through metallic gratings is a well established effect based on the collective resonance of corrugated screens. Being based on plasmonic resonances, its bandwidth is inherently narrow, in particular, for thick screens and narrow apertures. We introduce here a different mechanism to achieve total transmission through an otherwise opaque screen, based on an ultrabroadband tunneling that can span from dc to the visible range at a given incidence angle. This phenomenon effectively represents the equivalent of Brewster transmission for plasmonic and opaque screens.     

The effect of metallic screens on the spectrum of exchange dipole hybrid electromagnetic-spin waves

A theory of exchange dipole hybrid electromagnetic-spin waves is elaborated. The waves propagate in arbitrary magnetized five-layer screened structures where a ferromagnetic layer is separated from the metallic screens by two insulating layers on both sides, the layers having different permittivities. Within this theory, the effect of the screens on the hybrid surface wave spectrum in layered structures is analyzed. The structures consist of a ferromagnetic film that is applied on an insulating substrate and is in contact with a ferroelectric plate.     

基于微孔硅阵列的像素化γ-CuI闪烁转换屏的研制及性能表征

以微孔硅阵列为模板,高纯CuI粉末为原料,采用压力注入法,成功制备了具有单分散微柱结构的像素化CuI闪烁转换屏。扫描电子显微镜(SEM)与X射线衍射(XRD)的测试结果表明,所制备的转换屏中CuI微柱连续、致密,微柱柱径约为2.5μm、间隔约为1.5μm、柱长约为80μm,并具有良好的γ相晶体结构。在X射线激发下,所制备的像素化γ-CuI闪烁转换屏具有峰值波长位于680nm附近的红光慢发射带;掺碘后,该发射带被较大幅度的抑制,同时出现了峰值波长位于432nm的快发光峰;当碘掺杂含量达到10Wt%时,峰值波长位于680nm附近的红光慢发射带被完全抑制,只存在峰值波长位于432nm的快发光峰。采用刃边法测量了所制备的像素化γ-CuI闪烁屏的空间分辨率,结果显示其分辨率可达38lp·mm-1,表明该闪烁屏除拥有超快时间响应特性外,兼具很高的空间分辨本领,在X射线成像方面具有独特的应用价值。     

Nonlinear electrodynamics near a superconducting string

We calculate the effective action for photons in an arbitrary external field using the expansion in the inverse of the mass of the electron. The resulting effective lagrangian is used to calculate magnetization of the vacuum in the vicinity of a superconducting string. The magnetization current partially screens the current in the string and slows down the rate of growth of the current there. We also discuss the scattering of electromagnetic waves on a superconducting string with the nonlinear effects taken into account.     

Generation of infinitely long phase screens for modeling of optical wave propagation in atmospheric turbulence

Numerical modeling of optical wave propagation in atmospheric turbulence is traditionally performed by using the so-called 'split'-operator method, where the influence of the propagation medium's refractive index inhomogeneities is accounted for only within a set of infinitely narrow phase distorting layers (phase screens). These phase screens are generated on a numerical grid of finite size, which corresponds to a rather narrow slice (spatial area) of atmospheric turbulence. In several important applications including laser target tracking, remote sensing, adaptive optics, and atmospheric imaging, optical system performance depends on atmospheric turbulence within an extended area that significantly exceeds the area associated with the numerical grid.

In this paper we discuss methods that allow the generation of a family of long (including infinitely long) phase screens representing an extended (in one direction) area of atmospheric turbulence-induced phase distortions. This technique also allows the generation of long phase screens with spatially inhomogeneous statistical characteristics.     

用于光幕测试的时刻信息提取方法研究

从理论上分析了弹尖、弹底、幕中、弹中触发方式和广义相关算法这五种时刻信息提取方法,建立了弹丸穿过光幕的几何计算模型。结合工程实现中的问题如光幕厚度、厚度的一致性、放大电路一致性以及电路噪声,分析比较了不同方法对这些参数的敏感性,采用理论模拟信号在MATLAB上进行了仿真。结果表明,采用幕中、弹中触发和广义相关算法,可以精确提取时刻信息,而不受这些参数的影响。从理论上阐述了光幕厚度与测试精度的关系,其结果可以指导光幕靶和天幕靶的工程设计。     

双缝光幕靶设计

针对动力源火工品速度测试，设计了一种双缝光幕靶，实现对低速运动的火工品零件测速。与常规的单缝光幕靶不同，文中设计的双缝光幕靶将2个发射和接收装置融进一个单体结构，形成2个光幕。2台双缝光幕靶安装在同一个带有滑轨的固定架上，靶距可以任意调节。设计的双缝光幕靶可以替代传统的铜片测速方法，有效地提高了测量精度和实现了测量自动化。经过实弹射击和火工品试验验证，设计的双缝光幕靶测试系统可靠，测试数据准确。     

Heat Transfer in a Semitransparent Medium

The problem of 1D radiative-conductive heat transfer in a homogeneous isotropic gray medium near a planar diffuse nontransparent surface and in between parallel plates with different temperatures has been solved analytically. Nonconvective measurements of the thermal resistance of parallel-plane polyethylene foam specimens versus the number of layers (i.e., thickness) have been taken, both without and with thin screens made of aluminum foil. The applicability of the suggested theoretical approach and experimental technique for the measurement of radiative heat transfer and heat transfer by conduction in light heat-protective materials has been demonstrated.

     

The radiovisor,a receiver for direct visualization of infrared and microwave radiation using crystal phosphors

Different stages are considered in the formation of the visible images of infrared and microwave radiation fields in a radiovisor based on the use of crystal phosphor screens having high-temperature sensitivity and containing nonselective absorbers of the registered radiation. Expressions are obtained for the basic characteristics of the radiovisor, namely the threshold sensitivity, the dynamic range, the response delay, and the resolution. It is shown that the calculation results (with account taken of real parameters of luminors and infrared and microwave radiation absorbers, as well as of specified conditions of heat transfer and of ultraviolet excitation of the screens) are in satisfactory agreement with the experimental data. The possible range of variation of the interrelated properties of the radiovisor are discussed and examples of its application are given.     

An improved three-dimensional display system

Ultrasonic scans are taken in the usual way in a number of planes a regular distance apart, say 1 cm. These are transferred through the optics of the device onto a single film or plate in the form of small transparencies. Through the same optics, now working backwards, using stroboscopic illumination, the transparencies are projected onto a set of ground perspex screens mounted along a helix on the circumference of a rotating drum. Each component image is thus formed in the right position relative to the others. Images of different depths can be formed in different colours improving discrimination. Brightness of the images of different depths is variable independently of the others, further improving discrimination. The angle of viewing is extremely wide. None of these advantages can be achieved by holography.     

γ-CuI超快闪烁转换屏的制备与性能表征

以石英基片为衬底,采用真空热蒸发法,通过调控衬底温度制备出了具有微柱结构、柱径在μm量级、厚度约17 μm的γ-CuI超快闪烁转换屏。在X射线激发下,所制备的γ-CuI超快转换屏具有峰位在430 nm的快成分发射峰和峰位在700 nm的慢成分发射带,其中快成分发射峰占总发光的主要部分;随着衬底温度由170 ℃升高至210 ℃,转换屏430 nm发射峰的强度会逐渐减弱,而700 nm发射带的强度则逐渐增强,这可能是由于较高的衬底温度会造成碘流失从而引起转换屏中碘空位增加、铜空位减少所致(Cu/I增大),碘流失的假设得到了卢瑟福背散射实验的验证。γ-CuI超快转换屏的晶体结构呈(111)晶面择优取向,且不随衬底温度而变化,当衬底温度升高至210 ℃时,由于CuI分子获得的动能增加,转换屏还会出现微弱的(220)和(420)晶面的取向。当衬底温度由170℃增至190 ℃时,转换屏的微柱结构会随之优化,微柱结构明显,但当衬底温度进一步增至210 ℃时,由于表面扩散和体扩散效应加剧,微柱结构会随之退化。最后,采用刃边法测量了所制备γ-CuI转换屏的空间分辨率,结果显示170,190和210 ℃衬底温度条件下所制备的转换屏,其空间分辨率分别为：4.5,7.2和5.6 lp·mm-1,微柱结构有助于提高转换屏的空间分辨率。     

Comparison of gold leaf thickness in Namban folding screens using X-ray fluorescence

In this work, the thickness of the gold leaf applied in six Japanese folding screens is compared using a nondestructive approach. Four screens belonging to the Momoyama period (~1573–1603) and two screens belonging to the early Edo period (~1603–1868) were analyzed in situ using energy dispersive X-ray fluorescence, and the thickness of the applied gold leaf was evaluated using a methodology based on the attenuation of the different characteristic lines of gold in the gold leaf layer. Considering that the leaf may well not be made of pure gold, we established that, for the purpose of comparing the intensity ratios of the Au lines, layers made with gold leaf of high grade can be considered identical. The gold leaf applied in one of the screens from the Edo period was found to be thinner than the gold leaf applied in the other ones. This is consistent with the development of the beating technology to obtain ever more thin gold leafs.     

Characterization of a Namban folding screen from the Edo period by means of EDXRF,SEM‐EDS and Raman spectroscopy

In this work, a multianalytical approach is employed to characterize the materials used in a Namban folding screen that depicts the arrival of the Portuguese to the port of Nagasaki. Portuguese sailors reached Japan in 1543 and initiated what was to be known as the Namban trade. This interaction between Portuguese and Japanese was meticulously recorded by artists in the form of valuable and rare folding screens. The present screen, attributed to the Edo period (~1603–1868), is what we could consider a second‐generation screen, a copy of scenes and characters that appear in screens from the Momoyama period (~1573–1603) but in increased scale and minor detail. The materials used in the screen were identified by means of in situ energy dispersive X‐ray fluorescence. Complementary results were obtained by Raman and scanning electron microscopy coupled to energy dispersive spectrometry analysis of microsamples taken from the screen. The palette used in this artwork resorts to gold, malachite, azurite, vermillion, red lead, white oyster shell, and carbon black. Differences were found, when compared with previously studied screens, i.e. the use of mixtures of pigments, namely vermillion with red lead in an orange shade of red and also the mixture of vermillion and carbon black to obtain a brown color. Special emphasis was given to the characterization of the golden areas and study of techniques of gold application. Copyright © 2013 John Wiley & Sons, Ltd.     

Scintillation efficiency and X-ray imaging with the RE-Doped LuAG thin films grown by liquid phase epitaxy

Very thin scintillator imaging plates have recently become of great interest. In high resolution X-ray radiography, very thin scintillator layers of about 5–20 μm are used to achieve 2D-spatial resolutions below 1 μm. Thin screens can be prepared by mechanical polishing from single crystals or by epitaxial growth on single-crystal substrates using the Liquid Phase Epitaxy technique (LPE). Other types of screens (e.g. deposited powder) do no reach required spatial resolutions. This work compares LPE-grown YAG and LuAG scintillator films doped with different rare earth ions (Cerium, Terbium and Europium). Two different fluxes were used in the LPE growth procedure. These LPE films are compared to YAG:Ce and LuAG:Ce screens made from bulk single crystals. Relative light yield was detected by a highly sensitive CCD camera. Scintillator screens were excited by a micro-focus X-ray source and the generated light was gathered by the CCD camera’s optical system. Scintillator 2D-homogeneity is examined in an X-ray imaging setup also using the CCD camera.     

神光III核心X射线分幅相机

神光III装置核心X射线分幅相机将用于激光装置性能验收实验和宽范围的高能量密度物理、惯性约束聚变物理及基础物理实验研究.相机系统主要为记录神光III装置靶的时间分辨X射线发射设计,利用可更换的鼻椎实现具有二维空间分辨或者一维谱分辨的靶形貌时间分辨图像.神光III装置核心X射线分幅相机将被嵌入到一个铝制空气包中,空气包具有大容量冷却平板和一个特制的环境监测传感器阵列.相机设计很多部分不同于早期X射线分幅相机,如一套全新的阻抗匹配方案,曝光时间从0.07-1.5 ns可调,先进的荧光屏,脉冲屏压电路,准确的模块定位,独特的监控系统和完全远程计算机控制.其中先进的荧光屏和脉冲屏压电路已经获得初步应用.     

斜入射弹丸速度测量系统研究

天幕靶是用于测量弹丸速度较为普遍的光学测量仪器。在测量弹丸速度时,要求弹道垂直于天幕靶的靶面,当弹道不垂直预定靶面时,弹丸飞越两个天幕靶靶面的实际距离与两靶靶距存在一定的误差,斜入射角度越大误差越大。提出了一种用6个天幕构成天幕阵的速度测量系统。当弹丸以任意方向穿越6个天幕时,测时仪记录弹丸穿越各个天幕的时间间隔,根据这些时间间隔便可以求出弹丸的速度值和速度的飞行方向。该方案解决了弹丸斜入射时速度测量不准的问题,特别适用于枪弹末速度的测量。     

The acoustic performance of building façades in hot climates: Part 1—Courtyards

The acoustic performance of perforated screens of unusual geometry was investigated by means of model work and computer simulation resulting from diffraction theory in which the barrier produces an amplitude gradient (thnadner) or a phase gradient (splitter). The results indicate that the protection obtained is similar to that of a solid thin barrier of equal height for a wide range of frequencies when the receiver is near the barrier. The thnadner and splitter screens were then examined, by means of one-tenth scale models, as a part of a courtyard. The results show that a considerable reduction in traffic noise is achieved which is again of the same order as that of a courtyard with a solid wall.