OCDMA系统中2-D码和3-D码

光码分多址(OCDMA)技术主要应用在接入网中。设计大容量的地址码是该技术实用化的前提。本文在构造2 D素数码的基础上提出了一种用于OCDMA系统的空域/频域/时域3 D地址码。这种码基于素数序列运算。理论分析和数学计算结果表明，3 D码比2 D码的容量更大，系统带宽效率更高，误码率(BER)更低，表现出的性能更好。     

Two-wavelength micro-interferometry for 3-D surface profiling

Three-dimensional non-contact optical techniques for rapid and accurate mapping of micro-machined surfaces are important for the optoelectronic industry. Interferometry is a well-established technique for 3-D surface profiling. The conventional interferometric surface profilers using a single wavelength offer excellent vertical resolution, but a serious limitation to their use is that they can only handle smooth profiles and step heights less than half a wavelength. In this paper we describe a two-wavelength micro-interferometric setup for 3-D surface profile characterization of smooth as well as rough micro-specimens. The method removes ambiguity associated with the single-wavelength data and also extends the phase measurement range compared to the conventional single-wavelength interferometry. Seven-phase step algorithm is used for quantitative fringe analysis. The design of the system along with experimental results on smooth and rough micro-specimens is presented.     

石化废水的三维荧光光谱特征

石化废水是我国的主要工业废水之一,水量大、污染重.废水含有大量荧光物质,它的荧光光谱可以展现有机物组成,就像指纹一样与水样一一对应,被称为水质荧光指纹,简称水纹.论文通过对我国某大型石化企业的废水的三维荧光光谱特征的研究,揭示出石化废水荧光指纹丰富的特点,它含有近10个荧光峰,其中激发波长、发射波长(λex/λem)=...     

基于调制度测量的三维轮廓术

介绍了基于调制度测量的三维轮廓术的测量方法的原理和过程,并给出了实物测量。结果证明它在原理上是正确的、可行的、。此方法对三维轮廓术、三维传感及机器视觉的应用具有重要意义。     

3-D High-Order Edge-Element Analysis of 3-D Discontinuity Problems in Guiding Wave Structures

A 54-parameter high-order 3-D edge-element construction based on full magnetic vector variational formulas is discussed. This approach eliminates the spurious solutions efficiently with high accuracy. The analyses of the scattering characteristics of some 3-D discontinuity problems in guided wave structures verify the effective and reliability of the present method. The comparison between the numerical results obtained with 54 and 12-parameter edge element method shows that the present approach is more accurate and efficient.     

航空发动机内外涵道三维粘性流场的数值模拟

本文用数值模拟的方法,对某涡扇发动机从风扇入口到增压级出口以及整个外涵道的稳态流场进行了联算和分析,计算是在我们自主搭建的分布式平行网络平台上进行的。计算表明风扇叶片沿叶高马赫数变化较大,从叶根附近的0.56变化到叶顶的1.34。本文得出了比较详细的内外涵道流场的信息,为叶片优化设计以及气动声学评估提供了依据。     

3-D airflow measurement using smoke particles

A new 3-D PIV-technique that is applicable to low velocity airflow in a real space such as indoor airflow is proposed, and its performance is inspected through a simulation and an experimental application. In this technique, two parallel planes separated by short distance are illuminated by a pair of laser light sheets of different colors. The visualized images are separated with optical filters, and recorded on VTRs. The 2-D tracer pattern movement on visualized planes is tracked with pattern tracking and the movement normal to the visualized planes is calculated from the difference of tracer concentration between two planes. The simulation result showed that the algorithm proposed here can calculate 3-D velocity field adequately, but the experimental result showed that the luminous intensity difference between two visualized planes became the main source of experimental errors.     

一种新型彩色三维光学成像系统

提出一种新型三维彩色光学数字成像系统。此系统利用投影结构光对现实世界中的物体进行数字化，同时得到对应的彩色纹理。详细介绍了系统的硬件设计和软件体系结构设计，得到物体彩色纹理的两种不同方法；直接获取和从编码条纹中提取，给出了用该系统得到的实验结果并简单评价了系统的性能。此系统在反求工程、影视制作、三维游戏制作、医学应用等方面有远大的应用前景。     

从二维视图识别三维目标的多网络融合方法

提出了一种从二维视图识别三维目标的多网络融合方法,基于单个网络分类的置信度概念,有效地结合多个网络的输出结果作出最终分类判决,应用三个多层前向网络（隐层神经元数,初始权值等取不同值）,设计了基于分类确认度的多网络融合结构,对四类车辆目标进行的识别实验表明,所提出的多网络融合方法明显优于单个网络的识别性能。     

3-D holographic lithography of organic-inorganic hybrids

Fabrications of ordered three-dimensional structures with submicron lattice constants were performed on organic-inorganic hybrids using a holographic lithography technique recently reported in the literature. The possibility of such a patterning has previously been demonstrated from single nanosecond laser pulse irradiation of thin films of epoxy photoresist and mixtures of methacrylate-alkoxy-silane with Zr or Ti alkoxides. In the present work, UV irradiation of similar hybrid resins were carried out through repeated laser pulses of low energy with a twofold objective: (i) to study the interference stability for future chemical gas phase decomposition experiments and (ii) to obtain patterning through large film thickness (e.g. 1 mm). The influence of several parameters on the structuration was examined from observations by scanning electron microscopy and optical diffraction. Many interdependent parameters were considered in different steps of the process, namely (i) hybrid resin preparations with required properties of stability, transparency and viscosity, (ii) film coating on different substrates, (iii) UV irradiation (energy and number of laser pulses), (iv) ultrasonic dissolution of monomer, and (v) sample drying. As results, different structuration resolutions were observed as a function of these parameters. But if the influence of a few parameters was easily understood and controlled, it has also appeared that it was not the case of all of them.     

Vibrational spectra of styrene-H8, -D3, -D5, and -D8

Infrared and Raman spectra of C₆H₅CHCH₂, C₆H₅CDCD₂, C₆D₅CHCH₂, and C₆D₅CDCD₂ liquids are analyzed to assign their fundamental vibrations.     

三区振幅型三维超分辨光瞳滤波器的优化设计

光瞳滤波器是光学成像系统实现超分辨的基本元件之一，多数三维超分辨滤波器因结构复杂而难于实现。用MATLAB优化工具箱，采用非线性规划，对三区振幅型（1-0—1型）光瞳滤波器进行了三维超分辨优化设计。建立了优化模型，并给出了优化实例。结果表明所设计的滤波器较好地实现了横向和轴向三维超分辨，且轴向超分辨能力优于横向。该滤波器结构简单，容易实现。     

Performance Analysis of 2-D GRAPPA and Partial Fourier GRAPPA for 3-D MRI

The acquisition time of three-dimensional magnetic resonance imaging (3-D MRI) is too long to tolerate in many clinical applications. At present, parallel MRI (pMRI) and partial Fourier (PF) with homodyne detection, including 2-D pMRI (two-dimensional pMRI) and PF_pMRI (the combination of PF and pMRI), are often used to accelerate data sampling in 3-D MRI. However, the performances of 2-D pMRI and PF_pMRI have been seldom discussed. In this paper, we choose GRAPPA (generalized auto-calibrating partially parallel acquisition) as a representative pMRI to analyze and compare the performances of 2-D GRAPPA and PF_GRAPPA, including the noise standard deviation (SD), root mean-square error (RMSE) and g factor, through a series of in vitro experiments. A series of phantom experiments show that the SD, RMSE and g-factor values of PF_GRAPPA are lower than those of 2-D GRAPPA under the same acceleration factor. It demonstrates that the performance of PF_GRAPPA is better than that of 2-D GRAPPA. PF_GRAPPA can be used in any thickness of imaging slab, while 2-D GRAPPA can only be used in thick slab due to the difficulties in determination of the fitting coefficients which result from imperfect RF pulse. In vivo brain experiment results also show that the performance of PF_GRAPPA is better than that of 2-D GRAPPA.     

简化的三维体轮廓测量术

基于直接条纺位移分析的三维测量具有简单，快速，精确的特点，本给出了该方法的光学调制和计算机解调原理，以及用该方法进行简单三维测量的主要步骤。     

使用计算全息进行三维信息加密的方法研究

全息加密技术作为一种特殊的加密方法被广泛应用于信息加密和防伪等领域。在全息加密过程中,光波的波长、记录距离和入射角度等参数用做加密密钥和解密密钥被人们深入研究,但所加密的信息几乎都是二维信息。利用一种基于虚拟光学的对三维信息进行加密的方法,将三维物体的大小作为一个新的密钥被引入安全全息加密算法,其安全性能得到了极大提高;在此基础上提出了对再现三维图像进行客观评价的方法,即修正峰值信噪比法(PSNR,PeakSignal-to-Noise Ratio)。模拟实验证明,计算全息方法(CGH,Computer-Generated Hologram)作为一种对三维信息进行加密的方法是可行的,修正PSNR法对再现三维图像的质量进行定量分析是有效的。     

Steady needle growth with 3-D anisotropic surface tension

The effect of the anisotropic interfacial energy on dendritic growth has been an important subject, and has preoccupied many researchers in the field of materials science and condensed matter physics. The present paper is dedicated to the study of the effect of full 3-D anisotropic surface tension on the steady state solution of dendritic growth. We obtain the analytical form of the first order approximation solution in the regular asymptotic expansion around the Ivantsov’s needle growth solution, which extends the steady needle growth solution of the system with isotropic surface tension obtained by Xu and Yu (J. J. Xu and D. S. Yu, J. Cryst. Growth, 1998, 187: 314; J. J. Xu, Interfacial Wave Theory of Pattern Formation: Selection of Dendrite Growth and Viscous Fingering in a Hele-Shaw Flow, Berlin: Springer-Verlag, 1997).The solution is expanded in the general Laguerre series in any finite region around the needle-tip, and it is also expanded in a power series in the far field behind the tip. Both solutions are then numerically matched in the intermediate region. Based on this global valid solution, the dependence of Peclet number Pe and the interface’s morphology on the anisotropy parameter of surface tension as well as other physical parameters involved are determined. On the basis of this global valid solution, we explore the effect of the anisotropy parameter on the Peclet number of growth, as well as the morphology of the interface.     

Solid support flame synthesis of 1-D and 3-D tungsten-oxide nanostructures

In this paper we report the growth of 1-D and 3-D tungsten-oxide nanostructures on tungsten wire probes inserted in an opposed-flow oxy-fuel flame. The probe diameter and oxygen content in the oxidizer were varied to study their influence on the growth of tungsten-oxide nanostructures. The introduction of a 1-mm diameter W probe into the flame environment with an oxidizer composition of 50%O₂ + 50%N₂, resulted in the formation of 1-D nanorods on the upper surface of the probe. The formation of triangular, rectangular, square, and cylindrical 3-D channels with completely hollow or semi-hollow morphology was achieved by reducing the probe diameter to 0.5 mm. Whereas, the increase of the O₂ content to 100% and the employment of a 1-mm probe resulted in the growth of ribbon-like micron-sized structures. The lattice spacing of ∼0.38 nm measured for the 1-D W-oxides closely matches a monoclinic WO₃ structure. X-ray photoelectron spectroscopy analysis revealed that the larger 3-D structures also consist of WO₃ confirming that the chemical composition of the structures remains the same while varying the probe and flame parameters. The proposed growth mechanism states that the 3-D WO₃ structures are formed through the lateral coalescence of 1-D W-oxide nanorods.     

Steady needle growth with 3-D anisotropic surface tension

The effect of the anisotropic interfacial energy on dendritic growth has been an important subject, and has preoccupied many researchers in the field of materials science and condensed matter physics. The present paper is dedicated to the study of the effect of full 3-D anisotropic surface tension on the steady state solution of dendritic growth. We obtain the analytical form of the first order approximation solution in the regular asymptotic expansion around the Ivantsov’s needle growth solution, which extends the steady needle growth solution of the system with isotropic surface tension obtained by Xu and Yu (J. J. Xu and D. S. Yu, J. Cryst. Growth, 1998, 187: 314; J. J. Xu, Interfacial Wave Theory of Pattern Formation: Selection of Dendrite Growth and Viscous Fingering in a Hele-Shaw Flow, Berlin: Springer-Verlag, 1997). The solution is expanded in the general Laguerre series in any finite region around the needle-tip, and it is also expanded in a power series in the far field behind the tip. Both solutions are then numerically matched in the intermediate region. Based on this global valid solution, the dependence of Peclet number Pe and the interface’s morphology on the anisotropy parameter of surface tension as well as other physical parameters involved are determined. On the basis of this global valid solution, we explore the effect of the anisotropy parameter on the Peclet number of growth, as well as the morphology of the interface.      

台阶状面形的投影栅线法测量技术

采用光栅投影式三维轮廓术测量物体三维形貌时，当物体是台阶状物体时，物体表面的光栅条纹有阴影，导致后面的叠相还原过程无法进行。为了解决这一问题，将被测物体放在精密的旋转平台上。通过2次成像后，对2幅图像进行图像拼接，得到清晰的被光栅调制的物体图像。在图像拼接时，引入区域黑白对比度概念，区域的黑白对比度最大位置就是黑白区域的分界线。从而精确确定中间块2个边界的位置,然后进行图像拼接。最后采用双频光栅的傅里叶变换轮廓术来实现物体的三维形貌重建。结果表明：本方法简单、精度高，可以成功解决投影时具有阴影物体的三维形貌重建问题。