斜率和曲率的显色云纹及其级数识别

本文提出了用白光获得板面曲率的显色云纹方法。理论和实验分析说明，曲率和斜率的显色云纹可用于其级数的自动识别。本方法具有不必经过计算，实时确定条纹级数的优点，对于曲率和斜率测量方法和系统的完善具有实际意义。     

旋转锥镜相机研制动态曲率和斜率

采用旋转锥镜相机，进行激光散斑剪切照相，研测缓慢变形物体的动态曲率和斜率。拍摄一张散斑图即可获得曲率和斜率动态变化的全过程。     

用Talbot效应及云纹干涉法测试镜面反射体曲率和斜率的灵敏度分析

对用Talbot效应及云纹干涉法测试镜面反射体曲率和斜率的灵敏度进行了分析,同时给出了由于光栅稀密对测试的影响和相应的解释。这对从事这项工作或工程上利用此技术测试物体曲率和斜率提供了一个可行的方案。     

五孔剪切相机同时测量二维曲率,扭率和斜率

本文首次提出一种散斑剪切相机。该相机能把曲率、扭率和斜率的二维信息同时记录在一张双曝光散斑图上。对散斑图进行滤波分析时在频谱面上出现十三块互不重叠的衍射晕。在适当的衍射晕上滤波即可获得二维曲率、扭率和斜率的等值全场条纹。     

高阶截断误差的斜率和曲率混合型波前重构算法

研究了斜率和曲率混合型区域波前重构算法,提出了通过减小重构方程的截断误差来提高波前重构精度。利用泰勒展开推导了波前值、波前斜率和曲率值三者间的数学关系,得到了截断误差为相邻两波前测量点间距五次方的重构方程。将该方程用于波前重构中,提出了一种新的斜率和曲率混合型波前重构算法。通过重构仿真对比了该混合型算法与现有混合型算法的波前重构误差。结果表明,在忽略测量噪声的情况下,提出的算法将相对重构误差降低了约两个数量级;在考虑测量噪声的情况下,提出的算法在对高阶像差的重构时,具有更小的相对重构误差。提出的高阶截断误差的混合型波前重构算法较现有的混合型算法需要的计算量更小,更利于实时波前重构。     

离焦型Shack-Hartmann传感器的光斑矩波前重建

将光斑矩推广应用到离焦型Shack-Hartmann波前传感器中,提出了一种高精度的波前重建方法。针对离焦型Shack-Hartmann波前传感器,不仅提取了每一个微透镜光斑的质心偏移量,而且提取了每一个光斑的二阶矩,用于计算波前的局部斜率和局部曲率。将传统Shack-Hartmann传感器利用波前局部斜率进行波前重构的算法,推广到同时利用波前的局部斜率和局部曲率进行波前重构,并进行了数值模拟研究。数值模拟结果表明:所提波前重建算法可以进行高精度的波前重建。将peaks函数作为输入波前,采用所提波前重建算法得到的波前残差RMS为0.0327λ,小于常规算法的0.0903λ,表明所提算法可以显著地提高波前重建精度。     

懸樑的大撓度问题

引言 樑的初等弯曲理论(小挠度理论)假设樑在外力作用下变形很小即假设樑的挠度和斜率很小,以致 (1)樑未变形前的状态可以认为是樑在外力作用下的平衡状态; (2)樑曲率公式中斜率的平方项可以忽略不计。结果使得樑断面挠矩的计算以及挠曲方程的积分运算大为简化。 解决樑的大挠度问题时,由于樑的挠度和斜率并不小,樑本身变形所引起的外力作用的改变极为显著;因此必须以樑在外力作用下真正的平衡状态作为计     

能谱曲线的平展与量子混沌

指出了在利用能谱曲线分析量子混沌现象时,除了要做能量平展外,还应对曲线参数作平展处理.通过归一能谱曲线的均方根斜率,给出了一个普适的平展参数变量的方法.另外,如能谱曲线有平均倾斜现象,在参数平展前还应做相应的能量移动使其消除.讨论了经过平展处理后的能谱曲线的曲率与Gaspard-Rice-Mikeska-Nakamura无量纲曲率公式的关系. 关键词：     

冷拉拔超细Ni80Cr20合金丝卷曲因素分析

Ni80Cr20超细丝经冷加工后呈规则的三维螺旋卷曲状态。实验研究了拉拔角度、变形量、拉拔速度和模具定径区长度对超细丝材曲率的影响，制定了NiCr合金丝单模冷拉拔工艺。结果表明:随拉拔角度的增加，丝材曲率逐渐增加；变形量增加，拉拔角度为17时，丝材曲率没有明显规律，基本在0.56 mm-1左右，但拉拔角度为0时，丝材曲率逐渐增加；拉拔速度小于10 mmin-1时，曲率逐渐增加，大于10 mmin-1时，曲率增加趋势变缓，大于30 mmin-1曲率又有所下降；定径区长度越长丝材曲率越小。分析认为，NiCr丝材表面产生的附加切变形及切变层的流动速度的不一致性是丝材产生卷曲的原因，且曲率越大残余应力越大。为减小不均匀变形，冷拉拔工艺采用0拉拔、拉拔速度10 mmin-1、模具定径区长度为模具定径区直径的60%。     

空心微瓶谐振腔的曲率模型及其传输特性研究

提出了有关空心微瓶谐振腔的曲率变化模型并且研究了曲率对其传输特性的影响。仿真分析了微瓶谐振腔内回音壁模式的分布情况，随着曲率的增加，微瓶谐振腔对回音壁模式的束缚能力越强，使得内部光场能量也相应增加。通过控制熔接机的放电次数制得不同曲率的空心微瓶谐振腔，并且根据理想气体状态方程，推导了制备工艺中曲率模型，研究了空心微瓶谐振腔的曲率随放电次数的变化趋势。实验结果表明，曲率越大的空心微瓶谐振腔品质因子越高，可达到7.26×105，该结论在提升谐振腔的品质因子方面具有重要价值。     

On the zeros of absorptive diffraction cross sections

Distribution of the zeros of absorptive differential cross section is studied. Several rigorous bounds are deduced on the slope and curvature of diffraction peak. Energy dependence of the slope of diffraction peak and location of zeros of the cross section impose a constraint on ratio of curvature and slope of diffraction peak.     

反射面形状对光纤位移传感器光强调制特性的影响

为了分析反射面形状对单模光纤照射的光纤位移传感器光强调制特性的影响,建立了反射面不为平面时的光强调制特性函数模型.该模型基于单模光纤出射光场为修正近似高斯分布假设,通过引入反射面形状因子,分析了反射面形状因子对光强调制特性的影响规律.仿真结果表明,随着凹形反射面曲率半径值的增大,传感器特性曲线的前坡无显著变化,而后坡灵敏度增大,线性范围减小|随着凸形反射面曲率半径值的增大,传感器特性曲线的前坡仍无显著变化,而后坡灵敏度减小,线性范围增大|当曲率半径增大的一定值时,反射面的非平面性影响较小,其作用趋近于平面.     

Mesoscale simulations of curvature-inducing protein partitioning on lipid bilayer membranes in the presence of mean curvature fields

The membrane-surface migration of curvature-inducing proteins in response to membrane curvature gradients has been investigated using Monte Carlo simulations of a curvilinear membrane model based on the Helfrich Hamiltonian. Consistent with theoretical and experimental data, we find the proteins that generate curvature can also sense the background membrane curvature, wherein they preferentially partition to the high curvature regions. The partitioning strength depends linearly on local membrane curvature and the slope (or the coupling constant) of the partitioning probability versus mean curvature depends on the membrane bending rigidity and instantaneous curvature field caused by different proteins. Our simulation study allows us to quantitatively characterize and identify the important factors affecting the coupling constant (slope), which may be difficult to determine in experiments. Furthermore, the membrane model is used to study budding of vesicles where it is found that in order to stabilize a mature vesicle with a stable ‘neck-region’ (or stable membrane overhangs), the area (extent) of the intrinsic curvature region needs to exceed a threshold-critical value. The migration and partitioning of curvature-inducing proteins in a budding vesicle with a stable neck (with a characteristic negative value of the Gaussian curvature) is investigated.     

Measurement of pure curvature fringe distribution by using a double whole-field filtering technique

A double whole-field filtering technique to measure pure curvature fringe distribution of a deformed object is proposed. In this method, the slope fringes which are contained in the pattern of curvature fringes can be completely eliminated from the curvature fringes. Thus the pattern of pure curvature fringes with a good contrast can be obtained. Theoretical analysis and experimental results are given in this paper.     

Isgur–Wise function in a QCD-inspired potential model with WKB approximation

We use Wentzel–Kramers–Brillouin (WKB) approximation for calculating the slope and curvature of Isgur–Wise function in a QCD-inspired potential model. This work is an extension of the approximation methods to the QCD-inspired potential model. The approach hints at an effective range of distance for calculating the slope and curvature of Isgur–Wise function. Comparison is also made with those of Dalgarno method and variationally improved perturbation theory (VIPT) as well as other models to show the advantages of using WKB approximation.     

The effect of curvature variation on the scattering from rough surfaces

The general high-frequency, rough-surface reflection process is treated by the method of stationary phase. In particular, the principle of stationary phase is applied to each of the local reflection events, which appear to depend on surface curvature as well as slope. However, we show that the number of reflecting highlights also depends on curvature and cancels the curvature dependence. These results agree fully with those obtained by Beckmann and Spizzichino for the special case of the Gaussian process.     

Least-squares estimation for hybrid curvature wavefront sensors

In this paper general purpose weighted least-squares algorithms are introduced for use with hybrid sensors that provide slope and full curvature measurements, including the twist curvature. The algorithms are formulated for the traditional Fried and Southwell sampling geometries, as well as for a novel geometry specific to hybrid sensors. The estimation accuracy of the hybrid and Shack-Hartmann sensors are compared through simulations performed on phase screens that obey Kolmogorov turbulence theory.