长白山地区几种红景天品种的傅里叶变换红外光谱法鉴别研究

分别用石油醚,氯仿,甲醇对长白山地区的野生和栽培高山红景天和长白红景天进行了提取,并首次对提取物进行了傅里叶变换红外光谱法测定,还用红景天块做了相应的验证研究。结果表明,长白山地区的野生和栽培高山红景天和长白红景天的红外光谱图谱有明显不同,故可用作鉴别其品种或评价其质量的一种手段。     

Singularity spectrum of fractal signals from wavelet analysis: Exact results

The multifractal formalism for singular measures is revisited using the wavelet transform. For Bernoulli invariant measures of some expanding Markov maps, the generalized fractal dimensions are proved to be transition points for the scaling exponents of some partition functions defined from the wavelet transform modulus maxima. The generalization of this formalism to fractal signals is established for the class of distribution functions of these singular invariant measures. It is demonstrated that the Hausdorff dimensionD(h) of the set of singularities of Hölder exponenth can be directly determined from the wavelet transform modulus maxima. The singularity spectrum so obtained is shown to be not disturbed by the presence, in the signal, of a superimposed polynomial behavior of ordern, provided one uses an analyzing wavelet that possesses at leastN>n vanishing moments. However, it is shown that aC behavior generally induces a phase transition in theD(h) singularity spectrum that somewhat masks the weakest singularities. This phase transition actually depends on the numberN of vanishing moments of the analyzing wavelet; its observation is emphasized as a reliable experimental test for the existence of nonsingular behavior in the considered signal. These theoretical results are illustrated with numerical examples. They are likely to be valid for a large class of fractal functions as suggested by recent applications to fractional Brownian motions and turbulent velocity signals.     

The mm-wave dielectric measurements with an electric-field cross-correlation Fourier transform spectrometer

A method for measuring complex permittivity based on an electric-field cross-correlation Fourier transform spectrometer was proposed. Its principle can be extended over the whole microwave region. Two typical solid media, teflon and plexigrass, and a kind of sand were measured in 8mm-wave region by the method. The results show that this method has potentialities to perform accurate permittivity measurements.Supported by Foundation of Specialities Opened to Doctorate Study     

正切平方势阱中线性与非线性光学折射率变化的研究

利用正切平方势把电子的Schrodinger方程化为了超几何方程，并用超几何函数严格求解了电子的本征值和本征函数利用量子力学中的密度矩阵算符理论导出了正切平方势阱中的线性与三阶非线性光学折射率的解析表达式计算了该系统中的线性与非线性光学折射率变化的大小，讨论了影响折射率变化因素文章以典型的GaAs/AlGaAs势阱为例作了数值计算,数值计算结果表明，势阱的形状和入射光强对光学折射率的变化有着重要的影响.     

Effects of threshold on single-target detection by using modified amplitude-modulated joint transform correlator

Effects of threshold value on detection performance of the modified amplitude-modulated joint transform correlator are quantitatively studied using computer simulation. Fingerprint and human face images are used as test scenes in the presence of noise and a contrast difference. Simulation results demonstrate that this correlator improves detection performance for both types of image used, but moreso for human face images. Optimal detection of low-contrast human face images obscured by strong noise can be obtained by selecting an appropriate threshold value.     

The Ablowitz–Ladik hierarchy integrability analysis revisited: the vertex operator solution representation structure

A regular gradient-holonomic approach to studying the Lax type integrability of the Ablowitz–Ladik hierarchy of nonlinear Lax type integrable discrete dynamical systems in the vertex operator representation is presented. The relationship to the Lie-algebraic integrability scheme is analyzed and the connection with the τ-function representation is discussed.     

闪光X射线高速摄影荧光转换屏的设计和性质研究

本文描述了用于中间弹道高速摄影荧光转换屏的设计特点、性能测试和实验结果。文中讨论了Gd2O2S:Tb和(Zn,Cd)S对X射线的吸收系数、发光效率以及荧光光谱与变象管S-20阴极光谱灵敏度曲线相匹配的相关曲线;测试了转换屏的相对发光强度、分辨率及其余辉。实验证明本屏发光亮度比钨酸钙屏高60倍左右,屏分辩率达51p/mm,余辉时间为8μs,多幅摄影结果证明第一幅的图象对第二幅照片无“拖尾”现象,本屏已达到了中间弹道高速摄影转换屏的实用水平。     

Radial metrology application to whole-body measurement on hyperelastic tubular samples

This paper focuses on a one-camera/one-shot procedure able to get the whole deformation map of hyperelastic tubular samples. A challenging application of this approach is the investigation of the highly anisotropic and inhomogeneous arterial tissue mechanical response during inflation/extension tests. To address this issue, full field optical methods based on digital correlation (DIC), fringe projection (FP) and stereo-photogrammetry (SP) have been already proposed in literature to overcome limitations of the most widely adopted 2-D video dimension analyzer (VDA) systems.In this paper, the feasibility of a very straightforward full-field procedure that uses radial metrology concepts has been studied. The rationale behind the proposed method relies on the relation existing between image deformation of a world point reflected by a 45° concave conical mirror and the relative position of this point with respect to the specular surface. Under certain assumptions reasonably true for the application of interest, by using simple relationships, it is possible to retrieve the position of markers applied onto the sample surface with great precision. This procedure has several advantages such as the retrieval of the whole 360° surface map in one shot, the ease of application, the use of one single camera, the real-time measurement capability. Conversely, the proposed approach is suitable only for geometries with smooth transversal sections, needs sample preparation and its spatial resolution is limited by the sparsity of the surface control points.The paper describes first the theoretical basis of the procedure; then results of experimental tests on calibration samples and latex tubular specimens are presented and discussed. Further set-up improvements will allow the present procedure to be implemented for in-vitro inflation/extension tests on vascular segments.     

不对称离散分数傅里叶变换实现数字图像的加密变换

利用不对称分数傅里叶变换的特性,提出了一种图像加密变换的新方法。对图像的x,y方向分别实施不同级次的一维分数傅里叶变换,得到加密图像。解密方法就是对变换后的图像实施对应级次的分数傅里叶逆变换,只有当x,y方向的逆变换级次分别与原变换级次都相同或者满足周期条件时,才能恢复原图像。加密变换有效地提高了图像加密和防伪力度。数值计算验证了方法的正确性和可行性。     

基于小波变换的数字胸片自适应增强

利用图像自适应增强原理, 推导出小波域中的等价表示. 根据视觉生理心理学原理, 具体的增益系数由图像的背景灰度确定. 同时考虑到胸片中重要的细节信息位于中间频率的特性, 增益系数需要进行调整. 实验结果表明, 调整增益后的小波自适应增强方法能有效的增强数字胸片中的细节信息.