复指数系统在$L_{\alpha}^{p}$空间的不完备性

A necessary and sufficient condition is obtained for the incompleteness of complex exponential system in the weighted Banach space Lαp = {f：∫＋∞∞ ｜f（t）e-α（t）｜pdt ＋∞},where 1 ≤ p ＋∞ and α（t） is a weight on R.     

A smoothing-type algorithm for solving nonlinear complementarity problems with a non-monotone line search

The smoothing-type algorithm has been successfully applied to solve various optimization problems. In general, the smoothing-type algorithm is designed based on some monotone line search. However, in order to achieve better numerical results, the non-monotone line search technique has been used in the numerical computations of some smoothing-type algorithms. In this paper, we propose a smoothing-type algorithm for solving the nonlinear complementarity problem with a non-monotone line search. We show that the proposed algorithm is globally and locally superlinearly convergent under suitable assumptions. The preliminary numerical results are also reported.     

On sub‐Riemannian geodesics on the Engel groups: Hamilton's equations

We study the sub‐Riemannian geometry on the Engel group which is a step 3 nilpotent Lie group on . Our main result is to solve the Hamiltonian equations associated with the bi‐characteristic curves and express the solutions in terms of elliptic functions. Our model covers both the Heisenberg group and the Martinet case when setting certain parameters to be zero.     

A family of Steffensen type methods with seventh-order convergence

In this paper, based on some known fourth-order Steffensen type methods, we present a family of three-step seventh-order Steffensen type iterative methods for solving nonlinear equations and nonlinear systems. For nonlinear systems, a development of the inverse first-order divided difference operator for multivariable function is applied to prove the order of convergence of the new methods. Numerical experiments with comparison to some existing methods are provided to support the underlying theory.     

A Metastable Crystalline Phase in Two‐Dimensional Metallic Oxide Nanoplates

A simple method was adopted in which ultrathin cerium oxide nanoplates (<1.4 nm) were synthesized to increase the surface atomic content, allowing transformation from a face‐centered cubic (fcc) phase to a body‐centered tetragonal (bct) phase. Three types of cerium oxide nanoparticles of different thicknesses (1.2 nm ultrathin nanoplates, 2.2 nm nanoplates, and 5.4 nm nanocubes) were examined using transmission electron microscopy and X‐ray diffraction. The metastable bct phase was observed only in ultrathin nanoplates. Thermodynamic energy analysis confirmed that the surface energy of the ultrathin nanoplates is the cause of the remarkable stabilization of the metastable bct phase. The mechanism of surface energy regulation can be expanded to other metallic oxides, thus providing a new means for manipulating and stabilizing novel materials under ambient conditions that otherwise would not be recovered.     

基于平底孔反射体的双晶直探头测量模型

双晶探头在无损检测领域有着重要的应用,因而有必要建立一个超声测量模型来深入了解这类换能器的特点.通过将一个基于传递矩阵的多高斯声束模型和一个基尔霍夫近似方法获得的散射模型有效结合,建立了一个完整的纵波双晶直探头测量模型,用于预测平底孔缺陷体的回波信号.对比分析了平底孔反射回波信号的模型计算结果与实验测量结果,验证了该测量模型的准确性. 关键词： 超声测量模型 双晶直探头 多高斯声束模型     

Probing the Contraction and Association of Polystyrene Chains in Semidilute Solution by Non‐Radiative Energy Transfer

The interchain contraction and association of polystyrene in semidilute solution near the Θ temperature are studies using NET. The results reveal that during a drop of temperature, polystyrene chains pass through different states: a smooth change of conformation at temperatures above the Θ temperature, an accelerated contraction and association, aggregation of polymer chains, and then further continuous contraction below the Θ temperature. A pronounced hysteresis is observed during repeated heating. A viscosity study of the same solution was compared with the NET results. It indicates that NET can effectively be used to study conformational changes like contraction and association of polymer chains in a semidilute solution.

     

光纤式输油管道安全预警系统

提出了一种基于光时域反射原理(Optical Time Domain Reflectometer,ODTR)和分布式光纤传感器的输油管道泄漏实时监测技术。当输油管道发生泄漏时,光纤所处的温度场发生变化,利用光纤后向拉曼散射的温度效应,通过测量该处的温度变化来判断管道泄漏;当发生人为破坏(盗油)事件时,所产生的振动、压力等扰动信号使在光纤中传输的后向瑞利散射光产生明显的损耗特征,通过测量其光强的变化来检测管道是否受到扰动或破坏。用ODTR技术实现对光纤测量点的定位。实验结果表明,光纤长度5km(可延长),测温范围0～90℃(可扩展),温度测量偏差小于+ 5℃,对扰动外力和温度的定位偏差小于15m。该检测技术可以有效地提高输油管道泄漏监测的水平和油的防盗水平。     

Large-area hydrated vanadium oxide/carbon nanotube composite films for high-performance aqueous zinc-ion batteries

Science China Chemistry - Synchronously reducing/self-assembling strategy on Zn substrate was designed to fabricate large-area cation-doped hydrated V2O5/multi-walled carbon nanotube (D-HVO/MWCNT)...