遗传参数的极大似然估计

将Luo和Woolliams模型中的混合正态分布推广到混合对数正态分布.先用矩量法得到各参数的估计值,再将此估计值作为EM(Expectation Maximization)算法迭代的初值进行迭代,将矩量估计和极大似然估计结合起来,提高了EM算法的收敛速度并使修改后的模型更符合生物学事实.     

二维有序样本的有约束系统聚类

二维有序样本进行聚类必须满足两个要求：（１）类内各单元的相似性和类间的差异性；（２）各单元在位置上的有序性和类内的连通性。根据这些要求，将各单元观测指标间的距离矩阵作为聚类的指示矩将各单元之间的区位联系矩阵作为聚类的约束矩阵，在约束矩阵给出的约束条件之下，以类间单元指标的最大距离作为类间相似性指标，在指示矩阵中通过逐步聚并而将全部单元合并归类，即可得出满足要求的样本分类。     

Peroxidic perfluoropolyether for the covalent binding of perfluoropolyether chains on carbon black surface

Peroxidic perfluoropolyethers (PFPEs) are suitable tools for the covalent linkage of fluorinated groups on substrates containing aromatic moieties. Thus the thermal decomposition process of such fluorinated peroxides allowed the covalent linkage of PFPE radicals to the polycyclic aromatic structure of a graphitic carbon black. Contact angle measurements on molded pellets made with modified carbon black powders revealed a gradual enhancement of the hydrophobicity, which follows the increase of the fluorine content on the surface according to XPS experiments. BET analyses also revealed variations of the surface area of carbonaceous samples. Products and by-products were also evaluated by mass balances of decomposed portions of PFPE residues, respectively, PFPE chains bonded on carbon black and PFPE fluids obtained by homocoupling side-reactions. Modified carbonaceous materials were analyzed by solid state ¹⁹F-MAS NMR and the results are in agreement with the proposed radical mechanism.     

Thermally degradable thermosetting materials

Thermosetting materials have been widely used in a variety of applications but they generally display poor tractability after curing, which limits their use in applications where degradable or re-workable polymers are advantageous. Moreover, recyclability and biodegradability of thermosetting polymer also limit their use in applications where recycling and biodegradation are important. A variety of thermally degradable linkages within thermosetting materials have been studied both in academia and industry to develop re-workable adhesives. This review reports the recent development in thermosetting materials containing thermally breakable linkages that exhibit re-workability as well as potential for recyclability and biodegradability.     

Rare earth (Eu, Tb) mesoporous hybrids with calix[4]arene derivative covalently linking MCM-41: Physical characterization and photoluminescence property

MCM-41 mesoporous silica has been functionalized with two kinds of macrocylic calixarene derivatives Calix[4] and Calix[4]Br (Calix[4]=P-tert-butylcalix[4]arene, Calix[4]Br=5.11,17.23-tetra-tert-butyl-25.27-bihydroxy-26.28-bibromopropoxycalix[4]arene) through condensation approach of tetraethoxysilane (TEOS) in the presence of the cetyltrimethylammonium bromide (CTAB) surfactant as a template. Novel organic-inorganic mesoporous luminescent hybrid containing RE³⁺ (Eu³⁺, Tb³⁺) complexes covalently attached to the functionalized ordered mesoporous MCM-41, which are designated as RE-Calix[4]-MCM-41 and RE-Calix[4]Br-MCM-41, respectively, are obtained by sol-gel process. It is found that they all have high surface area, uniform in the mesostructure and good crystallinity. Measurement of the photoluminescence properties show the mesoporous material covalently bonded Tb³⁺ complexes (Tb-Calix[4]-MCM-41 and Tb-Calix[4]Br-MCM-41) exhibit the stronger characteristic emission of Tb³⁺ and longer lifetime than the corresponding Eu-containing materials Eu-Calix[4]-MCM-41 and Eu-Calix[4]Br-MCM-41 due to the triplet state energy of modified organic ligands Calix[4]-Si and Calix[4]Br-Si match with the emissive energy level of Tb³⁺ very well.     

Control of the optimum synthesis process of a four-bar linkage whose point on the working member generates the given path

This paper presents the optimum synthesis of a four-bar linkage in which the coupler point performs a path composed of rectilinear segments and a circular arc. The Grashof four-bar linkage whose geometry provides minimum deviations from the given problem for certain parts of the crank cycle is chosen. The motion of the coupler point of the four-bar linkage is controlled within the given values of allowed deviations so that it is always in the prescribed environment of the given point on the observed segment. The synthesis process tends to bring only those path segments that are beyond the boundaries within the prescribed boundary deviations. During the synthesis, allowed deviations change from the initial maximum values to the given minimum ones. Groups of mechanisms realising satisfactory approximation to the desired motion can be obtained by the method of controlled decrease of allowed deviations with the application of the Differential Evolution (DE) algorithm.     

原油期货与现货价格联动性的复杂网络拓扑性质

选取2002年11月25日至2010年9月24日的国际原油期货价格和中国大庆原油现货价格作为样本数据,用于研究原油市场中期货价格和现货价格之间的联动变化规律. 将期货与现货价格的联动性关系转换为由{Y,O,N}组成的联动性符号序列,用符号序列映射为联动性的波动状态;该波动状态由5个符号组成的滑动窗来表示,由此构成177种联动性波动模态. 将该模态作为网络节点,模态之间的转换作为边,构建期货与现货价格加权联动性复杂网络. 对联动性复杂网络的点强度、强度分布、加权集聚系数、平均最短路径、介数集中性和小团体性等     

Minimum degree condition for a graph to be knitted

For a positive integer $k$, a graph is $k$-knitted if for each subset $S$ of $k$ vertices, and every partition of $S$ into (disjoint) parts $S_1,\dots ,S_t$ for some $t\ge 1$, one can find disjoint connected subgraphs $C_1,\dots ,C_t$ such that $C_i$ contains $S_i$ for each $i\in \left[t\right]?\{1,2,\dots ,t\}$. In this article, we show that if the minimum degree of an $n$-vertex graph $G$ is at least $n∕2+k∕2?1$ when $n\ge 2k+3$, then $G$ is $k$-knitted. The minimum degree is sharp. As a corollary, we obtain that $k$-contraction-critical graphs are $?\frac{k}{8}?$-connected.     

Review of plasma turbulence experiments

Understandings of turbulent plasma have been developed along with nuclear fusion research for more than a half century. Long international research has produced discoveries concerning turbulent plasma that allow us to notice the hidden nature and physics questions that could contribute to other scientific fields and the development of technologies. Guiding concepts have been established up to now that stimulate investigations on turbulent plasma. Research based on concepts concerning symmetry breaking and global linkage requires observing the entire field of plasma turbulence for an ultimate understanding of plasma. This article reviews the achievements as well as contemporary problems regarding turbulence experiments associated with strongly magnetized plasmas in the last and present century, and introduces forthcoming experimental issues, including new diagnostics and physics-oriented devices related to plasma turbulence.