边界润滑条件下丁腈橡胶—金属磨损机理的研究

对矿物油润滑下丁腈橡胶－金属的磨损机理进行了研究。用扫描电子显微镜和Ｘ射线光电子能谱仪分析了橡胶及金属磨损表面形貌及其元素化学状态的变化，用傅里叶变换红外光谱仪分析了橡胶表面官能团的变化。结果表明：丁腈橡胶在应力集中处发生分子链断裂，形成高活性大分子自由基，大分子自由基与活化的金属发生力化学反应，生成金属－聚合物膜；同时，矿物油在金属表面还产生物理吸附和化学吸附膜。其与金属－聚合物膜在剪切力或磨屑     

镧助剂对Ni2P/SBA-15催化剂结构及加氢脱硫性能的影响

以SBA-15为载体,Ni(NO3)2·6H2O为镍源,(NH4)2HPO4为磷源,制备了初始P/Ni比为0.8的Ni,P/SBA-15前驱体,然后添加La助剂,再经过干燥、焙烧和程序升温氧气还原,制备了一系列不同La含量的La-Ni,P/SBA-15催化剂.采用XRD,N2-吸脱附和XPS对催化剂的结构进行了表征,以...     

高压下受限齿轮油成膜特性研究

本文揭示了在实际应用中极端工况下齿轮油的润滑特性.为了测量在高接触压力和不同温度条件下齿轮油的成膜能力,制作了高精度的膜厚测量仪,采用相对光强法实现纳米级膜厚测量.试验中共采用了5种性质不同的齿轮油,在纯滚动条件下测量接触区的油膜厚度,结果表明：随着接触压力的升高油膜厚度明显降低,但压力对润滑状态影响不大;温度的改变不但能影响油膜厚度,对润滑状态的影响也很明显;GL-5 85W/190和GL-5 85W/90齿轮油在接触压力达3 GPa温度提高到120℃时仍能形成很厚的油膜,但其余3种润滑剂在极端工况下成膜能力不足.本文最后根据试验结果还提出了含有丰富添加剂的齿轮油润滑模型.     

Study of electrochemical performances of multi-doped spinel Li1.1Mn1.85Co0.075Ni0.075O4 at 4.3 and 5 V

Li_1.1Mn_2???2x Co _x Ni _x O₄ (x?=?0, 0.075) spinel powders were successfully synthesized using a liquid stirred tank reactor method. The electrochemical performances of the undoped and doped spinels at 4.3 and 5 V were investigated by X-ray diffraction, field-emission scanning electron microscopy, and electrochemical impedance spectroscopy. The capacity of Li_1.1Mn_2???2x Co _x Ni _x O₄ could be divided into two parts, with 4.3 V as the dividing line in the 3–5 V charge–discharge range. Low capacity and good cyclic performance were obtained when cycled in the 3–4.3 V range for the multi-doped Li_1.1Mn_2???2x Co _x Ni _x O₄ spinel. In comparison with multi-doped spinel at 4.3 V, the results of the cyclic performance worsened at 5 V because the structure underwent further shrinkage, the charge transfer resistance rose and the electrolyte decomposed.     

Stokes问题的一种新的混合有限元逼近

为了求解Ｓｔｏｋｅｓ问题，本文构造出了一类新的满足ＢＢ－条件的有限元空间对，并给出了相应的超收敛分析．     

强地震的前兆次声波研究

利用在北京昌平安装的次声三点阵,对强地震前兆次声波进行了5年的连续观测。统计分析结果表明:强震前约10天内常能测到振幅很强的前兆次声。其三维动态频谱的特点是,振幅由弱逐渐加强,达到极值后变弱;先为长周期波(10-20分),紧跟着短周期波(5-10分),然后又出现更长的周期波,最后长短周期波一起出现。提前时间与三点阵到震中距离之间没有明显的关系,与震级之间也没有明显的关系。     

A HIGH ORDER METHOD FOR NON-SMOOTH FREDHOLM EQUATIONS

1.IntroductionConsidertheequationwherek(s,t)=k(f)tandf(s)aregiven,uistheunknownsolution.SinceitisrelatedcloselytoWiener-Hopfequationsandisveryimportantinpractice,therearemanynumericalresultsaboutit(e.g.[1--11]).Itiswellknownthattheaccuracyoftheapproximati…     

二氧化碳在正辛烷、正十四烷中对流扩散系数的测定

 建立了由细管驱替实验测定驱替气体在油藏流体中的对流扩散系数的测定方法。测定了CO₂分别在正辛烷、正十四烷中的对流扩散系数，并研究了驱替速度及正辛烷、正十四烷分子量对扩散的影响。     

Contribution of electrolyte pH and deposition potentials to the magnetic anisotropy of electrodeposited nickel films

The influence of electrolyte pH and cathode potential on the magnetic properties of single layer Nickel films electrodeposited on polycrystalline titanium substrates was studied. The films were deposited at the electrolyte pH=3.5±0.1, 2.5±0.1 and 2.1±0.1 by varying the deposition potentials (?1.2, ?1.5 and ?1.8 V vs saturated calomel electrode, SCE) applied in continuous waveform. The structural analysis by X-ray diffraction revealed that the films have face-centred cubic structure. Results of the magnetic measurements obtained by vibrating sample magnetometer (VSM) indicated that the magnetic properties were affected by the electrolyte pH and the cathode potentials in terms of magnetic anisotropy. At the highest pH the films deposited at the lowest potential had in-plane magnetic anisotropy. As the electrolyte pH decreased from the high (pH=3.5±0.1) to low (pH=2.5±0.1), which is aided by increasing the potentials, resulted in an almost magnetic isotropy in the films. However, isotropic magnetic behaviour was observed for the film deposited at the low pH combined with the high potential (?1.8 V vs SCE). Magnetic thickness profile of the samples obtained by VSM revealed that the isotropic films have a smoother magnetic variation across the film from one edge than the anisotropic ones. This is also verified with a microscopic observation by an optical microscope and the surface of the isotropic films is observed to be smoother than that of the anisotropic ones. Furthermore, all films were found to have planar magnetic anisotropy irrespective of the pH’s and the potentials.     

Free control of far-field scattering angle of transmission terahertz wave using multilayer split-ring resonators’ metasurfaces

To enhance transmission efficiency of Pancharatnam–Berry (PB) phase metasurfaces, multilayer splitring resonators were proposed to develop encoding sequences. As per the generalized Snell’s law, the deflection angle of the PB phase encoding metasurfaces depends on the metasurface period’s size. Therefore, it is impossible to design an infinitesimal metasurface unit; consequently, the continuous transmission scattering angle cannot be obtained. In digital signal processing, this study introduces the Fourier convolution principle on encoding metasurface sequences to freely control the transmitted scattering angles. Both addition and subtraction operations between two different encoding sequences were then performed to achieve the continuous variation of the scattering angle. Furthermore, we established that the Fourier convolution principle can be applied to the checkerboard coded metasurfaces.