舰船尾流散射特性的研究

利用Mie理论计算了单个气泡和舰船尾流横截面内气泡群的体散射函数.计算结果表明尾流中心的后向散射高于尾流边缘的.舰船尾流横截面内气泡群的散射与气泡大小,气泡尺寸分布和尾流深度有关系;在散射角180°附近后向散射增强显著;在散射角60°～80°之间,气泡群的散射相对于相邻角度有所增强.     

金属目标后向散射特性与表面温度场关系的研究

本文研究金属目标的后向散射特性与入射角、表面温度场之间的关系。根据现有条件设计了实验装置,并用该装置测量了部分实验数据。相关结论对激光探测等领域的研究具有一定的参考价值。     

OTDR系统波形的分析及其在光纤测量中的应用

本文利用瑞利散射原理分析了脉冲信号和脉宽大于、小于回波时间的方波信号的回波信号波形,并利用数值模拟得到了其理论波形图。根据原理自主搭建了一套光纤光时域反射仪（Optic Time Domain Reflectometer,简称OTDR）,用通信中通用的1550nm激光波长对样品光纤进行了实际测量,得到了与理论模拟完全一致的实测波形。通过对实测波形进行降噪处理得到了高精度的长度测量值和损耗测量值。长度测量的相对误差仅为0.0085%,与直接测量值比较,光纤传输损耗的相对误差为0.086%,理论与实验表明该OTDR系统完全可以与工程用的OTDR系统相媲美,在工程技术和教学研究中具有一定的应用前景。     

机载激光测深系统中回波信号大动态范围的偏振压缩

采用偏振检测方法 ,对机载激光测深实验系统接收到的大动态范围的水下目标反射的激光回波信号的压缩进行了实验研究。结果表明 ,偏振检测方法能压缩激光回波信号的动态范围至少达一个数量级 ,对水下的激光后向散射有较强的抑制作用 ;对探测水下目标反射的激光回波信号的影响不大。     

强脉冲离子束辐照混合的RBS研究

采用卢瑟福背散射(Rutherford backscattering spectroscopy,RBS)方法对强脉冲离子束辐照Ti/Al、Al/Ti和Ni/Ti三组薄膜/衬底体系所形成的混合层进行了研究.在Ni/Ti组合中形成了厚度比离子射程大得多的、混合度较高的梯度混合层.发现熔融态混合的程度不仅取决于两材料在熔融态的表面张力的差别,而且取决于它们熔点的差异.这两个参量较接近的混合程度较好.     

Azimuthal dependence and accurate determination of the half-angle in RBS channeling

Rutherford Backscattering Channeling (RBSC) is often used in the studies of single crystalline materials with regard to issues hinging upon the location of specific atomic species within the crystal lattice. Results are deduced from the characteristics of an angular scan curve representing the yield of close collision events from the constant scattering of the probing projectiles from the crystalline sample in a sequence of directions lying in a plane perpendicular to one particular crystal lattice direction. Such angular scans exhibit dips near major channels, and their angular widths are of concern. On a fundamental level, accurate determination of these angular widths in the case of axial channeling and their interpretation come up against uncertainties arising out of the absence of a preferred choice for the plane of scan. Here, we shall illustrate these uncertainties in a representative case, channeling of 2 MeV He⁺ ions in the 1 0 0 direction of Si.     

Determination of sulphur and copper depth distribution in patina layers using nuclear reaction techniques

A method for Cu and S profiling in patina layers was developed by applying a combination of nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy (RBS). The copper profiling was performed by using the 1327 keV γ-ray deexciting the third excited state to the ground state of ⁶³Cu produced by the reaction ⁶³Cu(p,p^′γ)⁶³Cu. For the determination of sulphur the 2230 keV γ-ray was used deexciting the first excited state to the ground state of ³²S formed through the reaction ³²S(p,p^′γ)³²S, which exhibits three sharp resonances at projectile energies 3.094, 3.195 and 3.379 MeV. The relevant cross-sections were measured in the energy range between 3.0 and 3.7 MeV in steps of 20 keV at 125° to the incident proton beam direction. The technique was tested using artificially produced and natural copper patina layers. Supporting information on the depth distribution of the constituent elements of the patina samples was obtained by p-RBS (E_p: 1.5 MeV, θ: 160°).     

The heterophase interface character distribution of physical vapor-deposited and accumulative roll-bonded Cu-Nb multilayer composites

We present a method for characterizing the full five parameter heterophase interface character distributions (HICD) using two-dimensional electron back-scatter diffraction (EBSD) images. We apply the HICD method to determine the orientation relationships and three-dimensional normal vectors of Cu-Nb interfaces in both physical vapor-deposited (PVD) pure Cu-Nb (4 μm individual layer thickness) and accumulative roll-bonded (ARB) alloyed Cu-Nb multilayer composites (200-600 nm layer thickness). The HICD analysis shows that {1 1 2}_Cu planes are most preferentially and frequently bonded with {1 1 2}_Nb planes with Kurdjumov-Sachs and Nishiyama-Wasserman misorientations in the ARB alloyed Cu-Nb multilayers. These interfaces differ from the {1 1 1}_Cu||{1 1 0}_Nb interfaces predominantly found in the PVD pure Cu-Nb multilayered thin films. Also, pure tilt type interfaces with a [1 1 1]/30° misorientation and {1 1 0}_Cu planes bonded to {1 1 2}_Nb planes were found in ARB alloyed Cu-Nb multilayers. In the ARB material the observed Cu-Nb interfaces differ from what would be obtained from random pairings of the Cu and Nb orientations in terms of the relative intensities (in multiples of random distribution) and shapes of the interface normal peaks, which indicates that these interfaces were preferentially selected during the high strain ARB process. The measured ARB textures along the interface also differ from the theoretical rolling textures for each bulk single phase metal, suggesting that during ARB layer refinement these interfaces have some influence on slip activity by constraining grain deformation or through the kinetics of dislocation-interface interactions.