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1.
It is considered the class of Riemann surfaces with dimT1 = 0, where T1 is a subclass of exact harmonic forms which is one of the factors in the orthogonal decomposition of the spaceΩH of harmonic forms of the surface, namely The surfaces in the class OHD and the class of planar surfaces satisfy dimT1 = 0. A.Pfluger posed the question whether there might exist other surfaces outside those two classes. Here it is shown that in the case of finite genus g, we should look for a surface S with dimT1 = 0 among the surfaces of the form Sg\K , where Sg is a closed surface of genus g and K a compact set of positive harmonic measure with perfect components and very irregular boundary. 相似文献
2.
Qiu‐Ying Huang Ming‐Yang Su Xiang‐Ru Meng 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(6):474-478
The combination of N‐heterocyclic and multicarboxylate ligands is a good choice for the construction of metal–organic frameworks. In the title coordination polymer, poly[bis{μ2‐1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole‐κ2N3:N4}(μ4‐butanedioato‐κ4O1:O1′:O4:O4′)(μ2‐butanedioato‐κ2O1:O4)dicadmium], [Cd(C4H4O4)(C9H8N6)]n, each CdII ion exhibits an irregular octahedral CdO4N2 coordination geometry and is coordinated by four O atoms from three carboxylate groups of three succinate (butanedioate) ligands and two N atoms from two 1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole (bimt) ligands. CdII ions are connected by two kinds of crystallographically independent succinate ligands to generate a two‐dimensional layered structure with bimt ligands located on each side of the layer. Adjacent layers are further connected by hydrogen bonding, leading to a three‐dimensional supramolecular architecture in the solid state. Thermogravimetric analysis of the title polymer shows that it is stable up to 529 K and then loses weight from 529 to 918 K, corresponding to the decomposition of the bimt ligands and succinate groups. The polymer exhibits a strong fluorescence emission in the solid state at room temperature. 相似文献
3.
John W. Goodby 《Liquid crystals》2017,44(12-13):1755-1763
ABSTRACTIn this article, the relationship between molecular architecture and the formation of twist-bend phases is reviewed under the context of shape dependency. We conclude that the twist-bend phase is a universal phenomenon, which occurs in a wide variety of materials, for dimers through to main chain polymers. In the process, the chemical information on molecular design is effectively lost or irrelevant, and molecular topology takes precedence over electrostatic interactions in mesophase formation. As a consequence of this macro-scale material, engineering by shape alone becomes a possibility, potentially more phases may be realised, and entropy is anisotropic. 相似文献
4.
A weighting of the edges of a hypergraph is called vertex‐coloring if the weighted degrees of the vertices yield a proper coloring of the graph, i.e. every edge contains at least two vertices with different weighted degrees. In this article, we show that such a weighting is possible from the weight set for all hypergraphs with maximum edge size and not containing edges solely consisting of identical vertices. The number is best possible for this statement. 相似文献
5.
6.
A. D. Matveev 《Journal of Applied Mechanics and Technical Physics》2004,45(3):440-448
This paper considers composites consisting of a set of typical composite multigrid finite elements whose structures are regular and different. Mean local errors are proposed for multigrid modeling of composites. 相似文献
7.
For the most part, analytical solutions for steady unsaturated infiltration have been restricted to infinite and semi-infinite seepage geometries, using the quasi-linear approximation for the hydraulic conductivity. We provide analytical series methods to solve the steady quasi-linear flow equations, in finite irregular seepage geometries. Unlike the classical approach, the series method has been modified, to cater for arbitrary boundary geometry and surface recharge distributions. The matrix flux potential and the stream function both satisfy the same governing partial differential equation, and the stream function formulation is used to estimate the series coefficients. For a finite vadose zone, the stream function solution does not uniquely determine the matrix flux potential, when flux boundary conditions are used. Consequently, the stream function solution applies to a range of moisture distributions, for given infiltration and evapotranspiration rates through the surface. 相似文献
8.
力学可以为农业现代化作贡献 总被引:10,自引:0,他引:10
农业现代化提出了许多与力学各个分支都有密切关系的问题.从农田耕作、农业物料性质、农产品烘干、水果和蔬菜生产、农业生物环境、节水灌溉、农业水土资源合理利用和作物生长等方面,介绍了有关的力学问题和目前的研究进展. 相似文献
9.
Polyurethane containing tertiary nitrogen atoms was synthesized from polyol, diphenylmethane diisoccyanate (MDI) and N‐methyl diethanolamine. The polymer was converted into cationomers by quarternizing with methacrylic acid (MAA) and then dispersed in water. In this reaction, methyl methacrylate (MMA) was used to decrease viscosity; at the same time, it was the monomer in the later reaction. Finally the cationic polyurethane dispersions were further polymerized with an oil‐soluble initiator, azobisisobutyronitrile (AIBN), water‐soluble initiator, K2S2O8 (KPS) and the mixture of AIBN and KPS. The different emulsion particles with shell‐core structure, “invert” shell‐core structure and “irregular” sandwich structure were obtained; the morphological structures were characterized by TEM observation, FT‐IR and particle size analysis. 相似文献
10.
Andrey A. Dobrynin 《Discrete Mathematics》2019,342(1):74-77
Distance between two vertices is the number of edges in a shortest path connecting them in a connected graph . The transmission of a vertex is the sum of distances from to all the other vertices of . If transmissions of all vertices are mutually distinct, then is a transmission irregular graph. It is known that almost no graphs are transmission irregular. Infinite families of transmission irregular trees of odd order were presented in Alizadeh and Klav?ar (2018). The following problem was posed in Alizadeh and Klav?ar (2018): do there exist infinite families of transmission irregular trees of even order? In this article, such a family is constructed. 相似文献