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11.
In this paper,it is shown that for a 3-dimensional small cover M over a polytope P,there are only 2-torsions in H1(M;Z).Moreover,the mod 2 Betti number growth of finite covers of M is studied. 相似文献
12.
Hanchul PARK 《数学年刊B辑(英文版)》2017,38(6):1321-1334
This paper deals with two things.First,the cohomology of canonical extensions of real topological toric manifolds is computed when coefficient ring G is a commutative ring in which 2 is unit in G.Second,the author focuses on a specific canonical extensions called doublings and presents their various properties.They include existence of infinitely many real topological toric manifolds admitting complex structures,and a way to construct infinitely many real toric manifolds which have an odd torsion in their cohomology groups.Moreover,some questions about real topological toric manifolds related to Halperin's toral rank conjecture are presented. 相似文献
13.
An on-line solid phase extraction-high performance liquid chromatography-tandemmass spectrometry method for the analysis of perfluoroalkyl substances (PFASs) in water samples was developed. The optimal analytical conditions were obtained through the optimization of the extraction efficiency of online solid phase extraction column, sample loading rate and loading volume, and the concentration of ammonium acetate in mobile phase. Under the optimal condition, the analytical method displayed good linearity (r2 > 0.99) for 12 PFASs (C5-C14 perfluoroalkyl carboxylic acids and C6/C8 perfluoroalkyl sulfonic acids) over a concentration range of 0.5-100 ng/L. The limits of quantitation for samples were between 0.025 ng/L and 0.5 ng/L and the relative standard deviations (RSD) of five consecutive analyses were less than 10% for 1 ng/L standard solution. Satisfactory results were obtained using this analytical method for the analysis of perfluoroalkyl substances in Antarctic ice core samples. The recoveries of all perfluoroalkyl substances were in a range of 73%-117% when the sampleswere spiked with standards at the concentrations of 2.5 ng/L and 25 ng/L. 相似文献
14.
L. A. Tkacheva 《Journal of Applied Mechanics and Technical Physics》2007,48(2):271-278
The vertical motion of a system of two identical seismic sources and a spring truck tractor on ice under the action of a shock
pulse from the seismic sources is studied to estimate the strength of ice. It is shown that during the pulse time, the interaction
of the masses of the seismic sources and the tractor is small and the compressibility effect of the liquid can be ignored.
Calculations show that for the seismic sources, the dynamic load far exceeds the static load and for the tractor, the static
load is maximal.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 2, pp. 147–155, March–April, 2007. 相似文献
15.
16.
本文研究用低爆速炸药复盖高爆速炸药在定滑移爆轰作用下飞板运动的计算方法,并对惯性复盖与炸药复盖的结果作出相互比较。 相似文献
17.
The nonstationary rectilinear motion of an amphibian air-cushion vehicle (AACV) on a water surface covered with finely broken ice is considered for various modes of velocity variation. The influence of
the water depth, flotation parameters, and mode of motion on the wave resistance of the vehicle is analyzed. Maneuvering methods
for increasing or decreasing the wave resistance of AACVs are proposed.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 1, pp. 97–102, January–February, 2007. 相似文献
18.
给出了关于冰的粘弹性微分本构模型的广义变分原理和冰载荷计算的有限元方法。修正的增量粘弹性矩阵有效地加速了迭代过程,计算了瞬态温度场下冰内压应力分布及对结构物作用力。其结果与实测数据定性吻合。 相似文献
19.
Eckhard Steffen 《Journal of Graph Theory》2015,78(3):195-206
Let G be a bridgeless cubic graph. Consider a list of k 1‐factors of G. Let be the set of edges contained in precisely i members of the k 1‐factors. Let be the smallest over all lists of k 1‐factors of G. Any list of three 1‐factors induces a core of a cubic graph. We use results on the structure of cores to prove sufficient conditions for Berge‐covers and for the existence of three 1‐factors with empty intersection. Furthermore, if , then is an upper bound for the girth of G. We also prove some new upper bounds for the length of shortest cycle covers of bridgeless cubic graphs. Cubic graphs with have a 4‐cycle cover of length and a 5‐cycle double cover. These graphs also satisfy two conjectures of Zhang 18 . We also give a negative answer to a problem stated in 18 . 相似文献
20.
Tomohiro Okuma 《Mathematische Nachrichten》2015,288(2-3):343-352
From a resolution graph with certain conditions, Neumann and Wahl constructed an equisingular family of surface singularities called splice quotients. For this class some fundamental analytic invariants have been computed from their resolution graph. In this paper we give a method to compute the multiplicity of an abelian covering of a splice quotient from its resolution graph and the Galois group. 相似文献