点衍射波前位相的测评

提出一种检测点衍射干涉仪关键部件针孔所产生的衍射光学波前的方法。介绍了点衍射波前的产生原理,分析了小孔质量状态、照明光路调整状态与波前各个像差分量之间的关系。基于信息光学基础理论,采用傅里叶变换和迭代算法,采集针孔衍射图像并进行计算分析,实现对衍射波前的位相复原以获得波前信息。阐述了测试方法的理论依据和计算公式,应用研制的位相复原分析计算软件测试并分析了实际采集的点衍射图像,通过15次的迭代,输出的位相值逐渐收敛,图像误差因子下降到0.12。目前,该方法已用于对针孔的筛选和针孔照明系统的装调中,实验结果证明了该测试方法的可行性。     

光学成像系统光学波前的高精度测试

基于扩展奈波尔-泽尼克理论,分析了不同出瞳振幅分布情况对光学系统焦面处光强分布的影响.针对光学成像系统出瞳振幅实际分布状态,提出了一种新的测试光学波前的方法,解决了相位恢复算法中出瞳振幅分布不均匀和快速傅里叶变换引入计算误差的问题.通过测评实验,对一光学系统进行了测试,获得的光学系统出瞳波前(PV)值为0.196 5λ...     

利用相位差异法检测镜面面形

为了验证相位差异波前检测器演示系统利用自带光源独立完成波前检测任务的能力,搭建了基于相位差异法检测镜面面形的实验平台。测试时在焦面和离焦面上同时采集短曝光图像,在已知离焦量的前提下解算出波前相位分布并恢复出目标,从而实现对大镜面像差的估计。为了进一步验证相位差异测量方法的准确性,对相位差异法与高精度的ZYGO干涉仪得到的测量结果进行了比较分析。实验结果表明:两种方法获得的面形误差分布及误差的峰谷值(PV)和均方根值(RMS)一致性很好,而波前RMS的测量精度达到了2.83/1 000λ。得到的结果表明提出的相位差异法能有效地检测出镜面的像差,且准确性很好。     

相位差异散斑法图像复原技术

为了克服大气湍流和光学成像系统像差引起的波前相位畸变,提出利用相位差异散斑法同时采集焦面和离焦面通道的单帧短曝光图像来估算波前相位畸变.结合夏克哈特曼波前探测器设计了针对扩展目标的相位差异散斑法高分辨率成像和相位估计对比实验,通过定量移动高精密平移台获得焦面和离焦面图像,并将解算的波前面形与夏克哈特曼波前探测器实测的波...     

光栅点衍射干涉法检测Φ400mm瞬态波前

提出了一种基于光栅点衍射干涉原理的Φ400mm瞬态波前检测方法。该方法使用位相光栅在参考光与测试光中引入横向错位,即在干涉图中引入线性载频,然后利用傅里叶变换相位解调法提取待测波前。基于标量衍射理论以及傅里叶光学理论建立了瞬态波前检测方案的理论模型,推导了线性载频公式,研究了影响载频大小的因素;基于基尔霍夫公式分析了针孔衍射导致的孔径角变化与能量衰减效应,给出了位相光栅的刻蚀深度公式。实验搭建了Φ400mm瞬态波前检测装置,采集了对比度良好的高线性载频干涉图。采用傅里叶变换相位解调法恢复波面,所得波面RMS值为0.105λ。与采用SID-4波前探测器测得的波面RMS值(0.101λ)基本一致,满足了Φ400mm瞬态波前测量的要求。     

不扩束激光粉尘粒度分布测试系统的设计与研究

主要研究不扩束激光粉尘粒度分布测试系统,对光衍射式激光粒度测试系统的光学装置进行改进,将激光的扩束系统去除,改为不扩束激光衍射系统,减小了测试系统的体积,光学结构变得简单,调节更加方便,光敏区也大大减小,降低了样品的损耗。并且通过改进的采用CCD的不扩束激光粉尘颗粒粒度测试系统对粉体进行测试,获得衍射光强图像,并利用计算机对衍射图像的光强分布作了分析。     

振动实验平台设计及振动模糊图像复原

为获得振动模糊图像,进而对图像进行复原处理,设计了单质体振动实验平台,将工业相机安装在振动平台上,进行图像实时采集。通过改变振动平台激振电机的速度,实现振动平台振动频率的改变,从而获得不同振幅条件下的振动模糊图像。采用图像点扩散函数复原算法对图像进行恢复,获得清晰的图像,实现振动模糊图像的复原及应用。     

激光棒干涉测量中单双通法的对比

由于激光棒具有细长的特殊形貌特征,传统的双通测试方法虽然灵敏度较高,但是往往存在明显的衍射效应和多重成像导致的边缘黑环,这会导致有效测量面积的缩减,对于小口径光学元件的测量尤为不利。为了克服这一缺陷,采用单通法测量激光棒的波前畸变,使用直角棱镜作为反射件,使得测试光仅通过激光棒一次,从而减少光路中的等效圆孔数和成像次数,抑制衍射和边缘重叠。利用展开的多小孔模型讨论了衍射效应的影响,并且从成像角度讨论边缘重叠的成因,从而得出单通法的优势。另外,为使参考光与测试光的匹配,需要将直角棱镜旋转至少5.40°偏摆角以提高干涉条纹的对比度。最终测得激光棒波前畸变的峰谷值为0.068λ,均方根值为0.012λ。     

位相复原技术在光学成像质量测评中的应用

对于大口径或特殊波段成像的光学系统,采用常规测试手段难以实现对光学系统成像质量的评估。而光学系统波像差是表征光学系统成像质量的重要指标之一。本文基于信息光学基础理论采用傅立叶变换和迭代算法通过对光学成像系统星点图像（光强点扩散函数PSF）计算分析,从而实现对光学成像系统位相的复原获得波像差信息。本文论述了有关的理论依据和分析计算公式;并研制了位相复原分析计算软件。通过计算机仿真与误差分析论证了研制的位相复原计算方法的正确性,复原误差小于5%。提出了在实际应用中采用此方法时减少复原误差的一种途径。通过实际采集的光学系统星点图像的位相复原实验验证了位相复原分析软件的适用性。此方法为非常规光学成像系统波相差的评估工作提供了新途径。     

一种基于振幅物体约束的相位恢复算法

针对传统近场衍射GS相位恢复算法需引入微位移平台以记录两个不同物距下的衍射图像作为输入,系统动态特性较差且相较于两帧记录时需要复杂成像位移结构的问题,提出一种基于单帧图像的相位恢复算法。该算法基于振幅物体零相位调制这一先验约束条件进行迭代相位恢复。利用该振幅算法对无透镜系统仿真结果进行相位恢复,实验结果验证了算法的可行性。与传统近场衍射GS算法相比,所提出的算法无论从迭代收敛速度还是结果准确性上都要优于传统算法。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...