拍摄脉冲全息肖象母版的研究

本文介绍了我们在拍摄脉冲全息肖象母版方面的研究工作.讨论了拍摄工作中所需要特别注意的若干问题.如:人眼安全、对易律失效、消除双频条纹、如何获得高亮度图象等问题.此外,还介绍了我们拍摄脉冲全息母版时,在未使用Q开关的情况下,同样获得了高质量全息肖象母版的经验.     

流动数值模拟中一种并行自适应有限元算法

给出了一种流动数值模拟中的基于误差估算的并行网格自适应有限元算法.首先,以初网格上获得的当地事后误差估算值为权,应用递归谱对剖分方法划分初网格,使各子域上总体误差近似相等,以解决负载平衡问题.然后以误差值为判据对各子域内网格进行独立的自适应处理.最后应用基于粘接元的区域分裂法在非匹配的网格上求解N-S方程.区域分裂情形下N-S方程有限元解的误差估算则是广义Stokes问题误差估算方法的推广.为验证方法的可靠性,给出了不可压流经典算例的数值结果.     

自参考交错子矩阵法确定混合物的化学组分数

本文提出SRISM方法解决这个问题,方法基于化学信息和噪声之间的频率差异. 首先,对原始波谱数据矩阵进行间隔采样,获得两个交错子矩阵. 原始化学信息在交错子矩阵中仍被完全采样,但是噪声并非如此. 然后,对两个交错子矩阵分别进行主成分分析,得到两组主成分. 最后,将两组主成分配对比较,从而获得原始波谱数据矩阵的化学组分数. 通过处理模拟数据和实验数据,SRISM方法能够有效克服信号重叠、微量组分和噪声等干扰因素,获得正确的化学组分数. SRISM方法具有原理完备、计算效率高、自动进行等优点.     

估算大气重力波参数的垂直扰动廓线获取新方法

重力波是大气中最基本的动力过程, 估算大气重力波参数是大气动力学理论研究的重要内容之一. 针对常用曲线拟合方法获取大气垂直扰动廓线存在的固有缺陷, 本文提出了估算大气重力波参数时垂直扰动廓线获取新方法. 基于小波变换中的影响锥曲线性质, 以影响锥曲线最大值作为区分背景场和扰动场的临界值, 利用10阶ButterWorth高通滤波器对小于临界值的信号进行滤波得到扰动场. 对实际大气过程高时空分辨率模拟纬向风和经向风垂直廓 线的Morlet小波和Fourier功率谱分析表明, 本文方法获得的扰动廓线中不再包含强背景场信息, 且不会引入虚假波信号, 克服了常用多阶曲线拟合方法的缺陷, 利用该方法可以估算出合理的大气重力波参数.     

自参考交错子矩阵法确定混合物的化学组分数（英文）

本文提出SRISM方法解决这个问题,方法基于化学信息和噪声之间的频率差异.首先,对原始波谱数据矩阵进行间隔采样,获得两个交错子矩阵.原始化学信息在交错子矩阵中仍被完全采样,但是噪声并非如此.然后,对两个交错子矩阵分别进行主成分分析,得到两组主成分.最后,将两组主成分配对比较,从而获得原始波谱数据矩阵的化学组分数.通过处理模拟数据和实验数据,SRISM方法能够有效克服信号重叠、微量组分和噪声等干扰因素,获得正确的化学组分数.SRISM方法具有原理完备、计算效率高、自动进行等优点.     

微穿孔板几何参数估算及其对吸声性能的影响

不规则孔微穿孔板几何参数无法直接获知,造成吸声性能计算困难,故提出一种微穿孔板几何参数估算方法。将不规则孔等效处理为圆孔,利用马氏理论关于圆孔微穿孔板的基本理论,建立了微穿孔板几何参数估算模型;将参数估算结果用于吸声性能预测,理论计算与实验结果吻合。根据微穿孔板几何参数对高吸声性能区域的影响,探讨了马氏理论适用极限与微穿孔板几何参数的关系,以及微穿孔板受粉尘污染后吸声性能演变规律。将微穿孔板参数点取在面积较大的高吸声性能区域中间部位,可获得较大的马氏理论适用极限;微穿孔板参数点位于高吸声性能区域右上部位时,一定程度的粉尘污染不会降低吸声性能.      

突发性镉污染饮用源水的应急处理技术

分析突发性镉污染提高不同倍数镉浓度处理方式的效果比较.考察了化学沉淀与混凝联用技术以及强化混凝与化学沉淀两种方法.探寻最佳pH、PAC的最佳投料、最佳处理时间、及处理镉的最大浓度.结果表明,pH=10,在处理低浓度时,化学沉淀与混凝联用技术处理较好,高浓度时,强化混凝与化学沉淀处理较好,在静止6h,对镉的处理效果最好.     

铜翅片蒸发器的亲水处理及制冷性能评价

以一台2匹的柜式空调为实验平台,利用量热计法对两台铜翅片蒸发器进行了制冷性能测试实验,一台未做处理,另一台做亲水处理,处理方法是把铜翅片蒸发器在配制好的化学溶液中浸泡一段时间.实验分别在低湿、标准、高湿三种不同的室内空气条件下进行.实验结果表明:(1)化学处理法是一种有效的改善铜翅片蒸发器表面湿润性的方法;(2)经过亲水处理的蒸发器与未处理的蒸发器的制冷量相当;(3)制冷量随室内空气湿度的增加而增加.     

Q值估算中的相关性

考虑各种相关性, 估算出,ψ与 J/ψ,之间非粲强衰变的比值,Q,为(26.0pm3.5)%.在估算过程中, 为了获得相关系数或方差, 采用了多种方法. 这些方法在数据的相关性分析中具有实际的应用价值.     

面部视频非接触式生理参数感知

为了在非接触条件下检测受试者的各项生理参数,本文设计了一种基于成像式光电容积描记技术,从手机录制的人脸视频中估算生理参数的方法.首先,提出了"小波变换-主成分分析-盲源分离"算法,用于提取出高信噪比的RGB三通道脉搏波信号.然后,分别从频域和时域角度对绿色通道信号进行处理,估算出心率值和呼吸率值;对红蓝通道的脉搏波信号...     

Transmission incoherent ultrasonic imaging of planar objects

A method of obtaining an ultrasonic image of a planar object with spatial variable transparency is proposed on the basis of the results of measuring the amplitude of the ultrasonic wave during the transmission ultrasonic probing. The case is considered in which the wave diffraction strongly affects the amplitude of the field behind the object and the phase is not measured. Even in the absence of phase information, this method allows one to restore the transparency masks of the planar object. The proposed mathematical apparatus can be also used in radio wave probing. Numerical simulation and processing of the experimental data demonstrated the comparability of this method and the aperture synthesis method using the phase information.     

用Stokes参量法实现数字同轴偏振全息的研究

提出了一种基于Stokes参量的数字同轴偏振全息方法.在实验中用一束线偏振光和一束椭圆偏振光作为参考光, 分别与物光进行干涉,通过拍摄在两个相互垂直方向上的全息图,计算出物光在这两个方向的振幅和相位信息, 从而得到物光的Stokes参量和物体的全偏振信息,实现对各向异性物体偏振态空间分布的图像重建. 实验结果表明,该方法可用于物体的全偏振特性的测量.这种方法在求出物光Stokes参量的同时, 也可消除零级像和共轭像的干扰,因此也可用于同轴或离轴全息.     

非平面参考光波的数字实时全息研究

将参考光视为是任意形式波面,讨论利用傅里叶变换提取物光频谱的可能性.研究结果表明,只要参考光相位函数的展开式中包含坐标的一次项,就可能使用傅里叶变换获取物光频谱.根据研究结果,提出在非平面参考光波情况下进行实时数字全息检测的方法,并给出实验证明.     

共轭读出法消除光致变色材料全息记录中的相位畸变

采用有机光致变色材料-吲哚俘精酰胺/PMMA薄膜作为可擦写全息记录介质,建立了一种能消除全息光存储中相位畸变的光路.此光路采用参考光的相位共轭光再现全息图,能有效消除物光路中由于光学元件失调和记录材料缺陷引起的相位畸变,是全息光存储中提高再现像像质的一种有用光路.     

多光束数字全息的研究

提出了一种多光束数字全息技术来解决当利用菲涅耳数字全息对全息图进行再现时,物体的多个表面无法同时再现得明亮、清晰.该方法是记录时采用多光束照明同一物体的多个表面,增强CCD上接收到的物体侧表面散射光的强度.实验成功地同时再现了物体的多个表面.同时,为了减弱再现像的散斑噪声,采用双线性插值和中值滤波处理图像,获得了质量高的三维物体的再现图像.     

Spectroscopy of unbound levels with the aid of Weinberg's quasiparticles

The resonant scattering of a neutron by a nucleus A is calculated using the method of Weinberg quasiparticles in a way modified from that of previous authors, with the object of obtaining fairly simple and explicit schematic formulae for both the scattering amplitude and the wave function that satisfy certain requirements of physical correctness. This is directed towards study of the unbound level both in n-A scattering and in its production as a final state by a stripping reaction. The level concerned involves the mixing of a single-particle resonance with other configurations. The structure aspect of the level is characterized, as for a bound level, by a spectroscopic amplitude Θ. The formula obtained for the wave function, while not requiring all the details of the nuclear model to be specified, should be rather accurate at alldistances.     

Imaging through an inhomogeneous layer with an acoustic antenna array

A method is proposed for obtaining images through a layer of an inhomogeneous medium by using an antenna array scanning in angle or space. The method is based on the wave front inversion, which allows one to form an undisturbed sound field on the object of location in an inhomogeneous medium. This property makes it possible to suppress the effect of the thin inhomogeneous layer on the signals observed at the array output. The technique consists in a mutual processing of two received signals, one of which is obtained by locating the objects through the inhomogeneous medium and the other is obtained by locating the same objects, in the same medium, by the front-inverted wave. The mutual processing procedure consists in using the first received signal to form a filter for the second signal. The method is tested by a numerical simulation.     

基于SLM的计算全息三维显示视角扩展编码

提出一种利用高分辨液晶空间光调制器的高衍射级来增大再现视角的计算全息编码方法.该方法首先对被记录物波的视角超出所用高分辨液晶空间光调制器允许范围的物波信息进行预处理,使预处理后的物波视角满足抽样定理;然后再进行计算全息编码.这种计算全息图可利用高分辨液晶空间光调制器的特定高衍射级恢复再现被记录物波.文中给出了该方法的编码原理及物波函数的预处理公式,并通过设计实例和实验结果证明了该方法的可行性.     

Phase-shifting digital holography with burst imaging method

The application of a burst imaging method to digital holography (DH) with multiple image capturing is firstly demonstrated. Nobody has discussed this approach explicitly, although the burst imaging method is not so uncommon. The burst imaging method intermittently captures several images with a high repetition rate followed by a relatively long rest time. If the light wave from an object has a much smaller complex amplitude change in the frame interval of an image sensor than the precision of the DH system, the wave can be regarded as being in a static state. As a result, this solves a fatal problem in DH for an object that moves or deforms while capturing multiple interference images. In this research, the burst imaging method was applied to phase-shifting DH, and it is simply implemented by a high-speed image sensor and a continuous phase shifting which is good for high-speed phase shifting. The measurement error was analytically solved for the movement speed of an object. Finally, the proposed method was experimentally used to observe an evaporating droplet of ethanol on a glass substrate.

     

Digital holography at millimetre wavelengths

In this paper, we describe a method for wavefront reconstruction at millimetre wavelengths using off-axis holography, a frequently used image recording technique at visible wavelengths first demonstrated in the 1960’s. Millimetre radiation has been highlighted recently in the imaging of non-conducting materials and objects, which often show significant transparency at these long wavelengths, even though opaque at visible and infrared wavelengths. Holography provides a method for recording a lens-less image of an object thus reducing loss of spatial frequency information, which is important for obtaining maximum resolution at long wavelengths. An experimental arrangement based on a simple form of Fresnel off-axis holography is described, with the object illumination and reference beams derived using two radiating horn antennas fed by a single coherent source (a Gunn diode oscillator operating at 100 GHz – wavelength 3 mm) via a 3 dB cross-guide coupler. The process is discussed in the context of imaging and in the validation of millimetre wave radiation sources (horns). We show that the entire fields from these and other components can be analysed using computational optics with data derived from a single measurement obtained using inexpensive equipment.