Ultrathin CuF2-Rich Solid-Electrolyte Interphase Induced by Cation-Tailored Double Electrical Layer toward Durable Sodium Storage

Solid-electrolyte interphase (SEI) seriously affects battery's cycling life, especially for high-capacity anode due to excessive electrolyte decomposition from particle fracture. Herein, we report an ultrathin SEI (3–4 nm) induced by Cu⁺-tailored double electrical layer (EDL) to suppress electrolyte consumption and enhance cycling stability of CuS anode in sodium-ion batteries. Unique EDL with SO₃CF₃-Cu complex absorbing on CuS in NaSO₃CF₃/diglyme electrolyte is demonstrated by in situ surface-enhanced Raman, Cyro-TEM and theoretical calculation, in which SO₃CF₃-Cu could be reduced to CuF₂-rich SEI. Dispersed CuF₂ and F-containing compound can provide good interfacial contact for formation of ultrathin and stable SEI film to minimize electrolyte consumption and reduce activation energy of Na⁺ transport. As a result, the modified CuS delivers high capacity of 402.8 mAh g⁻¹ after 7000 cycles without capacity decay. The insights of SEI construction pave a way for high-stability electrode.     

R600a喷雾冷却系统换热过程

以R600a压力式封闭系统喷雾冷却过程为研究对象,对其换热过程进行分析。对液滴撞击热面后的状态进行建模,分析了其运动状态。通过忽略液膜的对流换热,引入韦伯数来简化并修正雾滴与热源表面的对流换热系数关联式;借鉴二次成核理论,通过单位时间内,单位面积上覆盖的雾滴数量对核态沸腾换热系数关联式修正。通过上述分析,以对流换热和核态沸腾换热两种机理为中心,建立了新的换热系数关联式。通过与其他文献的关联式、实验测量值进行比较、不同工质进行比较、不同实验系统比较,发现该式预测值和实验测量值偏差在±20%以内,能够很好地预测压力式封闭系统喷雾冷却过程的换热系数。     

INTERFACIAL CRACK ANALYSIS IN THREE-DIMENSIONAL TRANSVERSELY ISOTROPIC BI-MATERIALS BY BOUNDARY INTEGRAL EQUATION METHOD

The integral-differential equations for three-dimensional planar interfacial cracks of arbitrary shape in transversely isotropic bimaterials were derived by virtue of the Somigliana identity and the fundamental solutions, in which the displacement discontinuities across the crack faces are the unknowns to be determined. The interface is parallel to both the planes of isotropy. The singular behaviors of displacement and stress near the crack border were analyzed and the stress singularity indexes were obtained by integral equation method. The stress intensity factors were expressed in terms of the displacement discontinuities. In the non-oscillatory case, the hyper-singular boundary integral-differential equations were reduced to hyper-singular boundary integral equations similar to those of homogeneously isotropic materials.     

Stability,bifurcation analysis and chaos control of a discrete predator-prey system with square root functional response

A discrete predator-prey system with square root functional response is presented. We study the existence and local stability analysis of the system. The conditions of existence of flip and Niemark-Sacker bifurcations in the system are derived. Furthermore, the chaotic behavior of the system in the sense of Marotto is proved. Numerical simulations are performed to show the consistence with analytical results and also to exhibit the complexity of the system. Finally, chaos control in the system is achieved via OGY feedback control method.     

Determining the full transformation relations in the transformation method

The transformation method provides an efficient way to control wave propagation by materials. However, the degree to which this transformation concept can be applied to other physical phenomena remains an open question. Recently, Hu et al. presented a general framework for determining the transformation relations of the physical quantities in an arbitrary partial differential equation (PDE) in its application scope according to the idea of the transformation method. In this paper, we will review the main concepts of this general theory, particularly the difference between this idea and usual methods. The flexibility of this method is shown using an example.     

微通道换热器在制冷空调系统中的应用分析

2010年6月1日实施的新能耗标准进一步推动了制冷空调行业的升级,微通道换热器以其体积小、重量轻、结构紧凑、耐高压、热阻低、换热效果好等特点开始逐步在汽车制冷空调系统、家用和商用制冷空调系统中得以应用.然而,国内在该领域的研究比国外起步晚,理论和实验研究都比较缺乏.文中对微通道换热器在制冷空调系统中的应用研究进行了总结...     

Singularity analysis and explicit solutions of a new coupled nonlinear Schrödinger type equation

The Painlevé test is performed for a new coupled nonlinear Schrödinger type equation. It is shown that this equation passes the integrability test and is P-integrable. By means of the truncated singular expansions, we construct some novel explicit solutions from the trivial zero solution. Furthermore, the traveling wave solutions are presented by direct quadrature method.     

Superconductivity in the metallic–oxidized magnesium interface

Metastable superconductivity at 39–54 K in the interfaces formed by metallic and oxidized magnesium (MgO) has been observed by ac magnetic susceptibility measurements. The superconducting interfaces have been produced by the surface oxidation of metallic magnesium under special conditions.     

一般非线性渗流方程广义解的存在唯一性与Blow-up

In this paper,we consider nonnegative solutions to Cauchy problem for the general nonlinear filtration equations ut-Dj(aij(x,t,u)Diφ(u))+bi(t,u)Diu+C(x,t,u)=0,and obtain the existence,uniqueness and blow-up in finite time of these solutions under some structure conditions.