伊利石软岩铁路隧道开挖的有限元分析

针对伊利石软岩中单线铁路隧道的开挖特点,采用弹塑性、非线性和大变形的力学模型及岩土工程中常用的DruckerPrager准则,运用ANSYS软件进行数值分析,并从伊利石软岩的位移、应力角度出发,得出伊利石软岩的力学特性、滑动特性以及要加强对边墙部位支护的结论。     

上海某广场基坑抽水试验分析

以上海某广场为例,通过现场抽水试验确定基坑挖影响深度范围内地下水的分布特征、渗透系数和抽水影响半径等重要的水文地质参数,为基坑挖和降水工程提供设计依据与研究基础。     

Surface and chemical diffusion effects of nanowire electrodes in lithium-ion batteries

Science China Technological Sciences - Nanostructured electrodes with surface effect show a distinct advantage in prolonging the lifetime of lithium-ion (Li-ion) battery. In order to characterize...     

高职建筑结构课程教学与研究

根据高职水利类建筑结构的课程体系及特征,结合高等职业教育的特点,改革教学办法和手段,探讨培养学生实践能力和应用能力,提高学生创新素质,促进学生全面发展的教学模式.     

溅射压力对Ni纳米颗粒形貌控制的影响

采用磁控溅射方法制备Ni纳米颗粒,使用扫描电镜(SEM)、原子力显微镜(AFM)等表征其形貌结构。采用高压溅射喷嘴结构,研究改变溅射压力等工艺参数对Ni纳米颗粒尺寸与形貌的影响。实验表明,采用高压喷嘴结构,溅射压力为20~180 Pa之间可以获得尺寸为10~100 nm的Ni纳米颗粒。采用高压溅射喷嘴结构可以得到具有晶体结构特征的Ni纳米颗粒。     

前视红外图像质量评价指标研究

实时图像质量严重影响景象匹配性能,但目前尚无通用可行的评价标准来衡量其质量,而且不同匹配算法对各种图像特征的敏感性有差异,需要根据算法对图像质量评价问题展开分类研究。文中首先给出了图像质量评价的工作方式,然后从成像质量和目标凸显程度两个方面进行指标分析,提出了包括信噪比、模糊度、目标局部凸显程度和全局凸显程度在内的指标体系。实验表明,各指标与匹配性能之间具有单调一致关系。     

A Decomposition Route for Synthesis of Al2O3 Crystal and its Applications as Thermal Conductivity Filler

Platelike α‐Al₂O₃ powder was obtained at 850°C by thermal decomposition of ammonium aluminum carbonate hydroxide precursor, which was treated by hydrofluoric acid. The results showed the decomposition of the as‐prepared precursors experienced via three steps, adsorption of physical water, dehydration of crystalline water, and decomposition of the precursor, and the activation energies of the above three steps were calculated using the Coats–Redfern method. Meanwhile, the intermediate of (NH₄)₃AlF₆ obtained played an important role in decreasing activation energy of the decomposition and phase transformation. Moreover, the thermal conductivity of the epoxy resin filled with platelike alumina was improved obviously.     

A New Ferroelectric Phase of YMnO3 Induced by Oxygen‐Vacancy Ordering

Manganese oxides are good candidates of strongly correlated electron materials due to the uniqueness of electronic structure of manganese and the mobility of oxygen among lattice sites under external impacts. Here, we used electron beam as the excitation source to explore the structural evolution of YMnO₃ and identified a new phase under the radiation of electron beam in the transmission electron microscope. Analyses of the electron energy‐loss spectra reveal that this phase originates from ordered oxygen vacancy. We applied the first principles calculation to pick out the optimized stable structure with a lower polarization, and verified its correctness by electron diffraction and image simulations. Analyses of density of states indicate that weak Y–O covalence is favorable for the existence of ferroelectricity, supporting the electrostatic nature of ferroelectricity in the YMnO₃.     

填充系数对橡胶连续塑炼机塑炼效果的影响

以新型连续塑炼机为实验平台,天然橡胶为生胶原料,考察了填充系数对天然橡胶连续塑炼效果的影响。结果表明,在塑炼段、销钉段和挤出段3段机筒和机头冷却水温度依次为40,50,60,70℃,转子转速为30 r/min,填充系数为60%的工艺条件下,连续塑炼机具有最好的塑炼效果,天然橡胶门尼黏度的下降幅度最大,塑炼胶更加均匀。