All good (bad) words consisting of 5 blocks

Generalized Fibonacci cube Q_d(f), introduced by Ilic, Klavzar and Rho, is the graph obtained from the hypercube Q_d by removing all vertices that contain f as factor. A word f is good if Q_d(f) is an isometric subgraph of Q_d for all d ≥ 1, and bad otherwise. A non-extendable sequence of contiguous equal digits in a word μ is called a block of μ. Ilic, Klavzar and Rho shown that all the words consisting of one block are good, and all the words consisting of three blocks are bad. So a natural problem is to study the words consisting of other odd number of blocks. In the present paper,a necessary condition for a word consisting of odd number of blocks being good is given, and all the good(bad) words consisting of 5 blocks is determined.     

陆生植物黑麦草(Lolium multiflorum)对富营养化水体修复的围隔实验研究——总磷的净化效应及其动态过程

采用围隔系统研究了陆生植物黑麦草（Lolium multiflorum）对畜禽养殖富营养水体中主要营养元素磷的净化效应及动态过程．结果表明：浮床黑麦草在富营养化水体中生长良好，对富营养水体中的总磷具有明显的净化效果．当覆盖率为30％时，对总磷的去除率最高达到72．96％．对其去除水体总磷的动态过程拟合表明符合三次方程曲线．实验结果为陆生植物修复富营养水体的季节模式和机理的深入研究提供了科学依据．     

The degree sequence of Fibonacci and Lucas cubes

The Fibonacci cube Γ_n is the subgraph of the n-cube induced by the binary strings that contain no two consecutive 1’s. The Lucas cube Λ_n is obtained from Γ_n by removing vertices that start and end with 1. It is proved that the number of vertices of degree k in Γ_n and Λ_n is and , respectively. Both results are obtained in two ways, since each of the approaches yields additional results on the degree sequences of these cubes. In particular, the number of vertices of high resp. low degree in Γ_n is expressed as a sum of few terms, and the generating functions are given from which the moments of the degree sequences of Γ_n and Λ_n are easily computed.     

Chromatographic selectivity triangles

2010 marked the 50th anniversary of the use of selectivity triangles to characterize chromatographic phases. Such plots ultimately identify and quantify the blend of intermolecular interactions that occur between solutes and solvents/phases. The first chromatographic triangle was proposed by Brown and applied to GC stationary phases. Snyder then developed the influential solvent selectivity triangle (SST) based on the gas-liquid partition data of Rohrschneider. The SST was combined with simplex experimental designs to optimize RPLC separations. Subsequent criticisms of the work revolved around the inaccurate predictions that resulted from the SST. These inaccuracies ultimately relate to the inability of the SST to account for the effects of water on the interaction ability of organic solvents. Other criticisms focused on the selection of the three probe solutes (ethanol, dioxane, and nitromethane) that were used to define the apices of the SST. Here, the concerns include the lack of explicit consideration of dispersion interactions and the fact that the three probes do not represent any single intermolecular interaction but rather reflect a blend of intermolecular interactions. The SST approach was modified for NPLC by redefining the triangle apices to reflect the localization, general adsorption, and basicity of NPLC mobile phase modifiers. Because water is generally absent in NPLC, the triangle approach leads to better predictions for NPLC than for RPLC. In subsequent modifications of selectivity triangles, Fu and Khaledi have created a micellar selectivity triangle (MST) based on linear solvation energy relationships (LSERs) and Zhang and Carr have used the Dolan-Snyder hydrophobic subtraction model to create RPLC column selectivity triangles. We end this review by highlighting more recent methods for comparing selectivities and by discussing a new 3D visualization tool for classifying chromatographic systems as having similar or different fundamental energetics of retention and hence having similar or different selectivities.     

The hyperspace of the regions below continuous maps with the fell topology

For a Tychonoff space X,we use ↓USC F(X) and ↓C F(X) to denote the families of the hypographs of all semi-continuous maps and of all continuous maps from X to I = [0,1] with the subspace topologies of the hyperspace Cld F(X × I) consisting of all non-empty closed sets in X × I endowed with the Fell topology.In this paper,we shall show that there exists a homeomorphism h:↓USC F(X) → Q = [1,1] ω such that h(↓CF(X))=c0 = {(xn)∈Q| lim n→∞ x n = 0} if and only if X is a locally compact separable metrizable space and the set of isolated points is not dense in X.     

地基望远镜塔台圆顶结构形式及设计原则

综述了地基望远镜塔台圆顶的作用及功能,给出了台址选择的基本原则。介绍了国外典型塔台圆顶的结构型式、工作特点和适用环境,以3.67 m口径先进光电系统望远镜塔台圆顶为例,分析了圆顶内热控措施的特点,从而提出了现代望远镜塔台圆顶的热设计指导原则及设计时应考虑的相关因素。最后,对望远镜基墩的设计及分析方法进行了探讨。     

Buoyancy induced flow in a nanofluid filled enclosure partially exposed to forced convection

A numerical study was performed on natural convection for water–CuO nanofluid filled enclosure where the top surface was partially exposed to convection. The cavity has a square cross-section and differentially heated. Except exposed convection part on the top, all sides are adiabatic on horizontal walls. Effects of Rayleigh number (10³ ? Ra ? 10⁵), Biot number (0 ? Bi ? ∞), length of partial convection (0.0 ? L ? 1.0) and volume fraction of nanoparticles (0.0 ? φ ? 0.1) on heat and fluid flow were investigated. The results showed that for the case of high Biot number that heat transfer along the heated was enhanced by increasing the Rayleigh number mainly at the upper portion of the heated wall. When the top wall was totally exposed to convection, the results prevail that the heat transfer was more effective at high Biot number especially at the upper portion of the heated wall. For the case of high Biot number, the results prevailed that the heat transfer at the upper portion of the heated wall increases considerably at high exposed length to convection (L); however, for L ? 0.75 the effect of L was less pronounced. Contour maps for percentage of heat transfer enhancement were presented and it was shown that the location of maximum enhancement in heat transfer was sensitive to Ra, φ and L.     

Axi symmetric 2D simulation and numerical heat transfer characteristics for the calibration furnace in a rectangular enclosure

This paper presents axi symmetric 2D numerical investigation of the spherical thermocouple calibration furnace in a rectangular enclosure. The focus is on the flow structure inside the Saturn (a hollow spherical cavity), external flow behavior due to annulus block heating and the surface temperature uniformity. Mesh sensitivity analysis is adopted to extract the mesh with minimum number of nodes but with fast convergent finite element solution. The basic strategy here is that temperature perturbation error at a single point instead of a single element contributed to the total perturbation error qualitatively remains the same. Agreement between numerical simulation results and the experiment results is good with a maximum temperature deviation 10 °C for the cavity temperature 400 °C. Finally, standard numerical temperature uncertainty due to variation in thermal conductivity is computed through the sensitivity coefficient using uncertainty analysis.