实验／分析模态双协调综合的实现

本文讨论了实验/分析模态双协调综合实现中实验子结构转角自由度和集中力矩柔度的测量问题。首次提出基于有限元理论的双无加载概念,并通过仿真计算说明其在转角自由度测量的应用价值.最后以一汽车底架模型为实例,经过分析综合和实验(/分析)综合,实践了本文的主题.     

光栅常数的简便测量方法

本文给出光栅常数两种简便测量方法。     

On stability crossing curves for general systems with two delays

For the general linear scalar time-delay systems of arbitrary order with two delays, this article provides a detailed study on the stability crossing curves consisting of all the delays such that the characteristic quasipolynomial has at least one imaginary zero. The crossing set, consisting of all the frequencies corresponding to all the points in the stability crossing curves, are expressed in terms of simple inequality constraints and can be easily identified from the gain response curves of the coefficient transfer functions of the delay terms. This crossing set forms a finite number of intervals of finite length. The corresponding stability crossing curves form a series of smooth curves except at the points corresponding to multiple zeros and a number of other degenerate cases. These curves may be closed curves, open ended curves, and spiral-like curves oriented horizontally, vertically, or diagonally. The category of curves are determined by which constraints are violated at the two ends of the corresponding intervals of the crossing set. The directions in which the zeros cross the imaginary axis are explicitly expressed. An algorithm may be devised to calculate the maximum delay deviation without changing the number of right half plane zeros of the characteristic quasipolynomial (and preservation of stability as a special case).     

Successive projection method for solving the unbalanced Procrustes problem

We present a successive projection method for solving the unbalanced Procrustes problem: given matrix A∈Rn×n and B∈Rn×k, n>k, minimize the residual‖AQ-B‖F with the orthonormal constraint QTQ = Ik on the variant Q∈Rn×k. The presented algorithm consists of solving k least squares problems with quadratic constraints and an expanded balance problem at each sweep. We give a detailed convergence analysis. Numerical experiments reported in this paper show that our new algorithm is superior to other existing methods.     

A new construction of quantum error-correcting codes

In this paper, we present a characterization of (binary and non-binary) quantum error-correcting codes. Based on this characterization, we introduce a method to construct -ary quantum codes using Boolean functions satisfying a system of certain quadratic relations. As a consequence of the construction, we are able to construct quantum codes of minimum distance . In particular, we produce a class of binary quantum -codes for odd length . For , this improves the result by Rains in Quantum codes of minimal distance two, 1999, showing the existence of binary quantum -codes for odd . Moreover, our binary quantum -codes of odd length achieve the Singleton bound asymptotically.

Finally, based on our characterization some propagation rules of quantum codes are proposed and the rules are similar to those in classical coding theory. It turns out that some new quantum codes are found through these propagation rules.

     

The trace space and Kauffman's knot invariants

The traces in the construction of Kauffman's knot invariants are studied. The trace space is determined for a semisimple finite-dimensional quantum Hopf algebra and the best lower bound of the dimension of the trace space is given for a unimodular finite-dimensional quantum Hopf algebra.

     

Efficient Synthesis of Isoquinolines by AgNO3‐Catalyzed Sequential Imination‐Annulation of 2‐Alkynyl Aldehydes with Ammonium Bicarbonate

An operationally simple approach for the tandem synthesis of isoquinolines by the reaction of o‐alkynylaldehydes with ammonium bicarbonate via Ag‐catalyzed 6‐endo‐dig ring closure is described. The reaction conditions and the scope of the reaction are examined, and a variety of substituted isoquinolines are prepared in moderate to excellent yields.     

WO3改性方法对MnOx/TiO2催化剂低温催化NH3还原NO特性的影响（英文）

采用3种不同的浸渍过程制备了系列WO3改性MnOx/TiO2催化剂,并采用BET比表面积测试、X射线衍射、拉曼光谱、H2程序升温还原、高分辨扫描电镜和原位红外光谱等技术进行表征.结果显示,一步浸渍法和先钨后锰的分布浸渍法制备的催化剂中,Mn和W的协同作用提高了活性组分的分散状态,并阻止了钛载体的转晶;在所有的Mn基催化剂中,Mn物种主要以Mn2O3形式存在,但在15%MnOx-5%WO3/TiO2中出现了少量的MnO2;WO3的加入大大增强了催化剂的还原能力,提高了其表面酸位尤其是B酸的数量与强度,并促进了活性中间物(NH2)的生成.表面Lewis酸在低温SCR反应起主要作用,并且发现NH2也是活性很高的物种.在NH3低温催化还原NO的反应中,一步浸渍法制备的催化剂活性最高.     

Vibrational spectroscopic study of the mineral pitticite Fe, AsO4, SO4, H2O

Some minerals are colloidal and show no X-ray diffraction patterns. Vibrational spectroscopy offers one of the few methods for the determination of the structure of these minerals. Among this group of minerals is pitticite, simply described as (Fe, AsO(4), SO(4), H(2)O). In this work, the analogue of the mineral pitticite has been synthesised. The objective of this research is to determine the molecular structure of the mineral pitticite using vibrational spectroscopy. Raman and infrared bands are attributed to the AsO(4)(3-), SO(4)(2-) and water stretching and bending vibrations. The Raman spectrum of the pitticite analogue shows intense peaks at 845 and 837cm(-1) assigned to the AsO(4)(3-) stretching vibrations. Raman bands at 1096 and 1182cm(-1) are attributed to the SO(4)(2-) antisymmetric stretching bands. Raman spectroscopy offers a useful method for the analysis of such colloidal minerals.     

神奇的超流体

Science和Nature被誉为世界两大顶级杂志,主要报道当今自然科学研究最高水平的研究成果和进展.他们面向一般读者,属于综合性科学杂志,影响因子稳定在30左右.Science杂志1880年由爱迪生创办,1894年成为美国最大的科学团体"美国科学促进会"(AAAS)的出版物.全年共51期,为周刊,全球发行量超过150万份.英国的Nature杂志创办于1869年,曾发表达尔文、赫胥黎等大师的文章闻名于世.从2009年开始,《力学与实践》在《力学纵横》栏目发表朱克勤教授的系列科普文章,其特点是每篇文章的主题围绕Science和Nature的一篇论文展开,用通俗的语言介绍与力学研究相关的一些前沿问题,本期刊出"神奇的超流体".