Corrosion behavior of CrN, Cr2N and π phase surfaces on nitrided Ni-50Cr for proton exchange membrane fuel cell bipolar plates

The relationships between nitridation, microstructure and corrosion were studied for a thermally nitrided model Ni-50Cr (wt.%) alloy to gain insight into the protection of metallic bipolar plates in proton exchange membrane fuel cells (PEMFCs). Surface layers containing CrN, Cr₂N or ternary Cr-Ni-N π phase nitride were formed, dependent on the nitridation conditions. Studies in aerated pH 3 sulfuric acid at 80 °C indicated that the best corrosion resistance was exhibited by CrN + Cr₂N surface layers, which were more corrosion resistant than Ni-50Cr metal, Cr metal, and nitrided Cr. X-ray photoelectron spectroscopy (XPS) analyses indicated oxygen enrichment of the polarized surfaces in the form of Cr-oxide and Cr-oxynitride species. Such oxygen enrichment does not appear to result in detrimental increases in interfacial contact resistance/electrical properties of the surface.     

Dry and wet lab studies for some benzotriazole derivatives as possible corrosion inhibitors for copper in 1.0 M HNO3

With contrast to the traditional techniques of identifying and synthesizing new corrosion inhibitors in wet lab, a prior dry-lab process, followed by a wet-lab process is suggested by using cheminformatics tools. Quantum chemical method is used to explore the relationship between the inhibitor molecular properties and its inhibition efficiency. The density function theory (DFT) is also used to study the structural properties of three selected benzotriazole derivatives namely, benzotriazole-1-carboxamide (BCA), 1H-benzotriazole-1-acetonitrile (BAN) and benzotriazole-1-carbonyl chloride (BCC) in aqueous phase. It is found that when the benzotriazole derivatives adsorb on the copper surface, molecular structure influences their interaction mechanism. The inhibition efficiencies of these compounds showed a certain relationship to highest occupied molecular orbital (HOMO) energy, Mulliken atomic charges and Fukui indices. A wet lab study has been carried out using weight loss, Tafel polarization and impedance measurements to evaluate their inhibition performance in 1.0 M HNO₃ solutions at 25 °C. Adsorption takes place by a direct chemisorption on the exposed copper surface, while it most probably occurs via hydrogen bonding on the oxidized surface. BCA was the most effective among the tested inhibitors, while BCC was less effective than BAN. Results obtained from dry-lab process are in good agreement with those recorded from wet-lab experiments.     

Einfluss dehnungsabhängiger Werkstoffeigenschaften auf die Umformbarkeit von Blechwerkstoffen

Effect of strain dependent material properties on formability of sheet metals This paper describes strain induced effects on the change of material properties. Because of these effects the calculation of forming limit curve changes, too. Special attention is given to the material property caused differences between one or more stepped forming operations with main advantages in comparison to the today’s common practice.     

基于逆向工程的人体三维成像

文章介绍了一种用于逆向工程的三维激光测量系统,论述了其原理、结构,详细讨论了激光扫描、数据的实时提取与模糊加权均值滤波处理、图像再加工等若干关键技术问题,并提出了相应的解决方法.     

A new image registration scheme based on curvature scale space curve matching

We propose a new image registration scheme for remote sensing images. This scheme includes three steps in sequence. First, a segmentation process is performed on the input image pair. Then the boundaries of the segmented regions in two images are extracted and matched. These matched regions are called confidence regions. Finally, a non-linear optimization is performed in the matched regions only to obtain a global set of transform parameters. Experiments show that this scheme is more robust and converges faster than registration of the original image pair. We also develop a new curve-matching algorithm based on curvature scale space to facilitate the second step.     

Spin rotation and energy compression in the ILC Linac-to-Ring positron beamline

The Linac-to-Ring (LTR) beamline for positron beam injection into the damping ring at an energy of 5 GeV is considered. The beamline performs spin rotation and energy compression of the positron beam extracted from the booster linac. The lattice includes four 90-deg phase-advance FODO cells with bending magnets placed between them, a solenoid and RF structure. Basic parameters and optimal configuration details are discussed. An analytical treatment of the beamline is performed.     

MATLAB用于处理曲线拟合

介绍MATLAB曲线拟合功能,并通过绘制弯矩图的实际例子说明它在有限元绘图中的应用。     

孤岛油田渤21断块水体能量评价方法的研究与实践

油藏水侵计算公式已被普遍地认识。然而，在边底在水油藏水体能量大小估算中存在的许多实践问题限制了它的应用。本文基于胜利油区孤岛油田渤２１断块２０ａ注水开发历史，对区水体能量进行了评价，并在此基础上建立起一套完善的边底水能量评价的程序与方法。同时，对实践中的具体问题进行讨论。     

P- and SV-wave separation by polarization-dependent velocity filtering: application to vertical seismic profiles from Kola superdeep borehole, Russia

In multicomponent seismic surveys, separation of interfering compressional (P) and shear-wave (S) energy provides valuable information for the interpretation of mode conversions and seismic anisotropy. We present a technique for such a separation using a polarization-dependent velocity filtering. At the first step of the procedure, a linear two-channel filter is designed in the frequency-wavenumber domain, with filter coefficients determined by the angles of incidence of respective seismic waves. Due to several physical reasons, the filter is unstable near the high end of the P-wave spectrum. We stabilize the filter with the use of S-wave spectrum balancing. This operation results in a robust decomposition into P- and SV-responses, while retaining the full energy of the vector wavefield. We implement this method in a module of our seismic processing system. The module employs a versatile parametrization scheme, as well as structured data input/output. It is able to process VSP or surface data, with velocities varying by either depth or offset. Application of the module to the processing of an offset VSP from the Kola Superdeep Borehole demonstrates that the program successfully separates P- and S-wave phases in crustal VSP data.     

Self-assembled monolayer of 2-(octadecylthio)benzothiazole for corrosion protection of copper

Self-assembled monolayer (SAM) of 2-(octadecylthio)benzothiazole (2-OTBT) was formed on a fresh copper surface obtained by nitric acid etching. Optimum conditions for formation of SAM have been established. XPS, AFM and FTIR studies have been used to characterize the SAM. Corrosion protection ability of the SAM has been evaluated in aqueous NaCl solution using electrochemical impedance, EQCN, potentiodynamic polarization and weight-loss studies. 2-OTBT SAM is found to have excellent corrosion protection efficiency in the aq. NaCl solution. The mechanism of corrosion inhibition of copper by 2-OTBT SAM is discussed.