爆心距对爆破振动信号频带能量分布的影响

根据爆破振动信号具有短时非平稳的特点,利用小波包分析技术对满足分析要求的多段微差爆破振动信号的能量分布特征进行研究。首先,简略地介绍了小波变换与小波包分析的特点。其次,基于MATLAB对爆破振动信号进行小波包分析,得到了爆破振动信号在不同频带上的能量分布图。最后,总结了爆破振动信号频带能量的分布规律,重点探讨了爆心距对爆破振动信号频带能量分布的影响。结果表明,爆破震动信号在传播过程中,其主振频带有往低频发展的趋势,且宽度增加。     

孔径尺寸可控ZrO2多孔陶瓷的制备

在溶胶共沉淀法制备ZrO2的基础上，利用高分子悬浮聚合技术，将具有单一分散性的造孔剂球形聚甲基丙烯酸甲酯（PMMA）（700nm）和ZrO2分别制成悬浮液，通过混合、真空抽滤、煅烧的工艺，制备出孔径尺寸可控，孔径分布均匀的ZrO2多孔陶瓷。用X-射线衍射（XRD）和扫描电子显微镜（SEM）观察了ZrO2多孔陶瓷的相组成和显微结构，结果表明其具有孔径分布均匀的结构特点且ZrO2四方相结构没有改变。     

南京供电公司EMS、DMS与控制中心的通信方式

介绍了江苏南京供电公司能量管理系统(EMS)、调度管理系统(DMS)和控制中心的现状,针对南京调度系统的现状提出了4种EMS、DMS与控制中心站的通信方式:由变电站远程测控终端(RTU)直接送往相关的主站系统;TASE.2协议的计算机通信;常规远动规约转发方式;网络规约通信方式。通过对几种方式的比较,决定采取网络规约通信方式,并分析了该方式的优点,阐述了该方式在南京供电系统的实施步骤。     

Controlled synthesis of porous spinel cobalt manganese oxides as efficient oxygen reduction reaction electrocatalysts

In this article, we report a facile precursor pyrolysis method to prepare porous spinel-type cobalt manganese oxides (Co _x Mn_3-x O₄) with controllable morphologies and crystalline structures. The capping agent in the reaction was found to be crucial on the formation of the porous spinel cobalt manganese oxides from cubic Co₂MnO₄ nanorods to tetragonal Co₂Mn₄ microspheres and tetragonal Co₂Mn₄ cubes, respectively. All of the prepared spinel materials exhibit brilliant oxygen reduction reaction (ORR) electrocatalysis along with high stability. In particular, the cubic Co₂MnO₄ nanorods show the best performance with an onset potential of 0.9 V and a half-wave potential of 0.72 V which are very close to the commercial Pt/C. Meanwhile, the cubic Co₂MnO₄ nanorods present superior stability with negligible degradation of their electrocatalytic activity after a continuous operation time of 10,000 seconds, which is much better than the commercial Pt/C electrocatalyst.

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Surface wave propagation in sandy layer overlying a liquid saturated porous half-space and lying under a uniform liquid layer

Dispersion of Rayleigh-type surface waves is studied in a sandy layer under a uniform layer of homogeneous liquid lying over liquid-saturated porous solid half-space. The frequency equation in the form of a ninth-order determinant is obtained and evaluated. Special cases have been deduced and dispersion curves for the phase velocity and wave number have been plotted for a particular model.     

Toward Scalable Fabrication of Hierarchical Silica Capsules with Integrated Micro‐, Meso‐, and Macropores

Hierarchical porous structures are ubiquitous in biological organisms and inorganic systems. Although such structures have been replicated, designed, and fabricated, they are often inferior to naturally occurring analogues. Apart from the complexity and multiple functionalities developed by the biological systems, the controllable and scalable production of hierarchically porous structures and building blocks remains a technological challenge. Herein, a facile and scalable approach is developed to fabricate hierarchical hollow spheres with integrated micro‐, meso‐, and macropores ranging from 1 nm to 100 μm (spanning five orders of magnitude). (Macro)molecules, micro‐rods (which play a key role for the creation of robust capsules), and emulsion droplets have been successfully employed as multiple length scale templates, allowing the creation of hierarchical porous macrospheres. Thanks to their specific mechanical strength, these hierarchical porous spheres could be incorporated and assembled as higher level building blocks in various novel materials.     

甲烷在硅(110)圆孔表面物理吸附特征的对比

基于第一性原理广义梯度近似的方法(GGA)对比研究了甲烷分子在多孔硅(110)不同位置分布的圆孔表面物理极化特征.计算结果表明:相邻孔的位置分布及其内部吸附的甲烷分子间的作用会影响甲烷在圆孔表面的吸附特征.吸附后甲烷的C-H键布局增加,C-H键长变化很小,圆孔表面硅原子的少量电子转移至甲烷,甲烷成键轨道的态密度的离域性增加.同时发现单个甲烷分子在竖直分布圆孔表面吸附时,甲烷吸附能较大而且系统的结构相对稳定.