关于一类立方图的可连通性

文献[1]中提出阶为n(n≥3)的路的立方图是可圈图当且仅当n为奇数,本文主要证明阶为n(n≥3)的路的立方图是可连通图当且仅当n为奇数,从而加强了文献[1]中的结论.     

Rational Synthesis of Molybdenum(V) Tetramers Consisting of [Mo2O4]2+ Dimers Held Together by Bridging Phosphinate Ligands and the Tungsten(VI) Dimer [(CH3O)2(O)W(μ-O)(μ-O2PPh2)2W(O)(CH3O)2]: Structural and Theoretical Considerations

Reacting MoO₂(acac)₂ with Ph₂POOH or Me₂POOH in EtOH results in the formation of the tetranuclear molybdenum (V) clusters Mo₄(μ ₃-O)₄(μ-O₂PR₂)₄O₄, PR₂ = PPh₂, 1, or PMe₂, 2, in functional yields (>90% and 55% respectively). The reaction of WO₂(acac)₂ with Ph₂POOH in MeOH affords the tungsten dimer [(CH₃O)₂(O)W(μ-O)(μ-O₂PPh₂)₂W(O)(CH₃O)₂], 3. The single crystal X-ray determined structures of complexes 1–3 are reported. In 1 and 2, the four Mo=O units are interconnected by four triply bridging oxygen atoms, resulting in a distorted cubic-like structure for the Mo₄(μ ₃-O)₄O₄ units. Each molybdenum atom forms two additional Mo–O bonds with two oxygen atoms from different adjacent phosphinato ligands. Complex 3, a tungsten dimer, contains packing disorder and consists of bridging oxo and diphenylphosphinato ligands. The bonding of 1 and 2 assessed by density-functional methods showed that bonding between the Mo(V) centers occurs through σ overlap of the d _xy orbitals. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Dedicated to the memory of Professor F. A. Cotton. Veritas numquam perit.     

干涉型成像光谱仪仿真及评价系统的实现

针对星载的干涉型成像光谱仪提出了一种基于归一化互相关系数的光谱数据立方体重建质量的量化评价方法,并以工程化的要求作为仿真背景条件,建立了一个通用仿真系统。通过仿真,证实了基于归一化互相关系数的成像光谱仪数据立方体重建质量量化评价方法是可行的。     

Finite Element Computations of Flow around a Wall-mounted Cube

In this paper, we present the application of a finite element scheme to full three-dimensional incompressible flow around a cube mounted on the wall in a channel. This scheme is based on the Petrov-Galerkin weak formulation using exponential weighting functions. The incompressible Navier-Stokes equations are numerically integrated in time by using a fractional step strategy with a second-order accurate Adams-Bashforth scheme. The workability and validity of the present approach are demonstrated through the results of streamlines and pressure coefficients in the flow field up to high Reynolds number regimes.     

Another universality property for crumpled cubes

Let C denote a crumpled n-cube in the n-sphere Sⁿ such that every Cantor set in its boundary is tamely embedded in Sⁿ. The main theorem shows C to be universal in the sense that however it is sewn to a crumpled n-cube D of type 2A, a large class containing most of the explicitly described examples, the resultant space is homeomorphic to Sⁿ.     

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.     

Elastic and inelastic scattering components in the angular intensity distribution of He scattered from graphite

The angular intensity distribution of thermal energy He beam scattered from highly oriented pyrolytic graphite (HOPG) surface has been measured by means of supersonic molecular beam scattering technique in the wide surface temperature range. To separate the elastic and inelastic scattering components, simple analysis method has been developed by applying the classical binary collision theory of the hard cube model (HCM). From the extracted elastic scattering component in the scattering distribution, the Debye temperature of the HOPG surface has been derived as 590 ± 30 K. On the basis of the HCM analysis for the extracted inelastic scattering components of He beam, the effective mass for the HOPG surface has been found to be 72 u (six carbon atoms).     

基于角锥棱镜和面阵CCD的动态基座航向角校准

研究用于飞行器等动态基座航向角校准的大范围、中高精度航向角度测量系统.系统采用2个面阵电荷耦合装置(CCD)检测反射光斑的相对位置,实时测定动态基座航向角,为避免基座晃动的影响,提出了角锥棱镜反射测量方法并设计了整套光路,所需元件少,结构简单,光路调谐简便,适合空中作业.根据预估参数搭建了实验系统,对面阵CCD传感器的检测信号进行阈值分割处理后,采用重心亚像素检测方法,定位精度达到0.4像元大小,航向角度测量不受基座晃动影响,测量精度优于1',测量范围满足±10°,为应用于外场实验打下了基础.     

Transition Dipole,Charge Transfer,and Electron-hole Coherence in Two-photon Absorption： Visualizations with Two Dimensional Site and Three Dimensional Cube Representations

The developed visualization methods of two dimensional （2D） site and three dimensional （3D） cube representations have been performed to show the orientation of transition dipole, charge transfer, and electron-hole coherence in two-photon absorption （TPA）. The 3D cube representations of transition density can reveal visually the orientation and strength of transition dipole moment, and charge different density show the orientation of charge transfer in TPA. The 2D site representation can reveal visually the electron-hole coherence in TPA. The combination of 2D site and 3D cube representations provide clearly inspect into the charge transfer process and the contribution of excited molecular segments for TPA.