Hierarchical nanowires for high-performance electrochemical energy storage

Nanowires are promising candidates for energy storage devices such as lithium-ion batteries, su- per（：apa.citors and lithium-air batteries. However, simple-structured nanowires have some limitations hence the strategies to make improvements need to be explored and investigated. Hierarchical nanowires with enhanced periormanee have been considered as an ideal candidate for energy storage due to the novel structures and/or synergistic properties. This review describes some of the recent progresses in the hierarchical nanowire merits, classification, synthesis and performance in energy storage applieat, ions. Herein we discuss the hierarchical nanowires based on their structural design from three major categories, including exterior design, interior design and aligned nanowire assembly. This review also briefly outlines the prospects of hierarchical nanowires in morphology control, property enhancement and application versatility.     

关于负超几何分布期望与方差算法的注记

研究了非还原取样模型中负超几何随机变量的联合分布,得到了若干有用的推论.据此给出了负超几何分布的期望和方差的一种分解算法.     

框架结构主动控制最优时滞研究

在结构振动主动控制中,时滞的大小对结构控制能量和响应均产生影响。在允许时滞的范围内,把结构控制能量和响应作为目标函数,数值仿真发现目标函数随着时滞的变化呈现曲线状态,这说明存在最优时滞。在目标函数处理方面,考虑到控制能量和响应数量级不一致,本文采用了无量纲化处理。同时,考虑到地震波的随机性,本文还推导了含控制力的改进的随机Newmark方法。最后给出了一个计算实例。实例表明本文所提出的方法是有效的。     

超导低电阻接头衰减法测试过程中的拟合偏差控制

超导技术在许多高新技术领域有着广泛而深远的应用前景,其中超导导体接头技术是超导发展过程中必不可少的关键环节之一,快速而又准确地评估低电阻接头显得尤为重要.本文在考虑超导体的E-J特性后,针对目前低电阻接头采用的衰减法测量,计算得出感应电流完整的衰减曲线方程-幂函数方程.对比目前广泛采用的指数方程拟合与采用幂函数方程拟合的偏差,指出采用指数方程代替幂函数方程拟合的必要条件,为接头电阻衰减法测试,尤其是低电阻接头情况下的测量提供参考.     

时频分析在旋转机械状态监测及故障诊断中的应用

本文简要介绍了时频分析方法的发展及其在旋转机械状态监测、故障诊断领域中的应用。并以一个实际监测系统为例，对其检测信号应用时频分析的方法进行了数据处理，对用传统傅立叶变换处理的结果与采用时频分析方法处理的结果进行了对比分析．     

Path-following interior point algorithms for the Cartesian <Emphasis Type="Italic">P</Emphasis><Subscript>*</Subscript>(κ)-LCP over symmetric cones

In this paper, we establish a theoretical framework of path-following interior point algorithms for the linear complementarity problems over symmetric cones (SCLCP) with the Cartesian P _*(κ)-property, a weaker condition than the monotonicity. Based on the Nesterov-Todd, xy and yx directions employed as commutative search directions for semidefinite programming, we extend the variants of the short-, semilong-, and long-step path-following algorithms for symmetric conic linear programming proposed by Schmieta and Alizadeh to the Cartesian P _*(κ)-SCLCP, and particularly show the global convergence and the iteration complexities of the proposed algorithms. This work was supported by National Natural Science Foundation of China (Grant Nos. 10671010, 70841008)     

A 3D mesh deformation technique for irregular in‐flight ice accretion

Aircraft holding around busy airports may be requested to sustain as much as 45 min of icing before landing or being diverted to another airport. In this paper, a three‐dimensional mesh deformation scheme, based on a structural frame analogy, is proposed for the numerical simulation of ice accretion during extended exposure to adverse weather conditions. The goal is to provide an approach that is robust and efficient enough to delay or altogether avoid re‐meshing while preserving (enforcing) nearly orthogonal elements at the highly distorted ice surface. Robustness is achieved by suitably modifying the axial and torsional stiffness components of the frame elements in order to handle large and irregular grid displacements typical of in‐flight icing. Computational efficiency is obtained by applying the mesh displacement to an automatically selected small subset of the entire computational domain. The methodology is validated first in the case of deformations typical of fluid‐structure interaction problems, including wing bending, a helicopter rotor in forward flight, and the twisting of a high‐lift wing configuration. The approach is then assessed for aero‐icing on two swept wings and compared against experimental measurements where available. Copyright © 2015 John Wiley & Sons, Ltd.     

Cohen–Macaulay Multi–Rees Algebras

Let A be a local ring, and let I ₁,...,I _r A be ideals of positive height. In this article we compare the Cohen–Macaulay property of the multi–Rees algebra R _A (I ₁,...,I _r ) to that of the usual Rees algebra R _A (I ₁ ··· I _r ) of the product I ₁ ··· I _r . In particular, when the analytic spread of I ₁ ··· I _r is small, this leads to necessary and sufficient conditions for the Cohen–Macaulayness of R _A (I ₁,...,I _r ). We apply our results to the theory of joint reductions and mixed multiplicities.     

The independence of initial vectors in the subdivision schemes

Starting with an initial vector λ = (λ(κ))κ∈z ∈ ep(Z), the subdivision scheme generates asequence (Snaλ)∞n=1 of vectors by the subdivision operator Saλ(κ) = ∑λ(j)a(k - 2j), k ∈ Z. j∈zSubdivision schemes play an important role in computer graphics and wavelet analysis. It is very interesting tounderstand under what conditions the sequence (Snaλ)∞n=1 converges to an Lp-function in an appropriate sense.This problem has been studied extensively. In this paper we show that the subdivision scheme converges forany initial vector in ep(Z) provided that it does for one nonzero vector in that space. Moreover, if the integertranslates of the refinable function are stable, the smoothness of the limit function corresponding to the vectorλ is also independent of λ.