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61.
62.
基于摇臂——转向架结构月球车的越障能力判断准则 总被引:1,自引:0,他引:1
对轮式移动系统进行越障分析时,常以垂直越障作为评价标准.但是,月球车在凹凸不平的月面上行驶时,垂直越障模型不具有一般性.为此,本文对基于摇臂-转向架结构月球车在任意路面的越障进行了研究.一般情况下,由于任意路面越障模型相对复杂,可以建立的独立平衡方程数目少于未知变量数,因此无法得到越障能力与路面参数的函数关系式.针对上述问题,文中将最大有效牵引力假设引入越障模型中,得到了一种任意路面越障能力的判断准则.通过算例分析,表明了所提方法的有效性. 相似文献
63.
Dr. Juan J. Nogueira Dr. Markus Oppel Prof. Leticia González 《Angewandte Chemie (International ed. in English)》2015,54(14):4375-4378
Phenothiazinium dyes are used as photosensitizers in photodynamic therapy. Their mode of action is related to the generation of triplet excited states by intersystem crossing. Therefore, rationalizing the factors that influence intersystem crossing is crucial to improve the efficacy of photodynamic therapy. Here we employ quantum mechanics/molecular mechanics calculations to investigate the effect of aqueous and nucleic acid environments on the intersystem crossing mechanism in methylene blue. We find that the mechanism by which the triplet states are generated depends strongly on the environment. While intersystem crossing in water is mediated exclusively by vibronic spin–orbit coupling, it is enhanced in DNA due to a second pathway driven by electronic spin–orbit coupling. Competing charge‐transfer processes, which are also possible in the presence of DNA, can therefore be suppressed by a suitable structural functionalization, thereby increasing the efficacy of photodynamic therapy. 相似文献
64.
苏振华 《数学的实践与认识》2017,(12):182-188
目前关于积图的交叉数的研究已经推广到六阶图与星图的积图.研究得到了一个特殊六阶图Q与n个孤立点nK_1的联图交叉数,然后通过收缩的方法,得到了Q与星图S_n的积图交叉数. 相似文献
65.
长三角地区在全国房地产"库存"的背景下,实现了房地产市场的不断向好.对长三角地区有关面板数据进行实证研究,实证结果表明房地产开发投资、医院床位数、工业生产总值与人均房地产成交面积呈正相关.城镇人口数,中、长期贷款利率与人均房地产成交面积呈负相关,高收入城市比低收入城市人均房地产成交面积低14.%,教育支出和城镇居民总的可支配收入对人均房地产成交面积影响不显著. 相似文献
66.
《Journal of separation science》2017,40(22):4294-4302
A directly‐coupled‐column ultra‐fast liquid chromatography coupled with diode array detection method for the determination of 12 allergenic disperse dyes in river water at sub‐ppb levels has been developed and successfully validated. The analytical method is based on the use of two different reversed‐phased columns connected through a two‐position switching valve. A baseline separation was achieved by proper selection of stationary phases, mobile phases, and the use of a gradient elution in both dimensions. Furthermore, an easy‐to‐handle magnetic solid‐phase extraction procedure was developed for the preconcentration of 12 allergenic disperse dyes from river water. An enrichment factor of 100 times was obtained. The results showed excellent performance in terms of trueness (76.8–99.0%), precision (intraday: 2.2–8.0%, interday: 3.3–8.2%), and sensitivity (limits of determination, 0.027–1.46 μg/L). Twenty real samples collected from the outfalls in the Yaojiang, Yongjiang and Fenghuajiang estuary were analyzed, and three of the studied compounds were found in one collected sample (12.6 μg/L for disperse blue 7, 11.6 μg/L for disperse blue 106, and 0.22 μg/L for disperse blue 3). 相似文献
67.
A drawing of a graph is pseudolinear if there is a pseudoline arrangement such that each pseudoline contains exactly one edge of the drawing. The pseudolinear crossing number of a graph G is the minimum number of pairwise crossings of edges in a pseudolinear drawing of G. We establish several facts on the pseudolinear crossing number, including its computational complexity and its relationship to the usual crossing number and to the rectilinear crossing number. This investigation was motivated by open questions and issues raised by Marcus Schaefer in his comprehensive survey of the many variants of the crossing number of a graph. 相似文献
68.
磨西河流域泥石流流域形态的非线性特征 总被引:1,自引:0,他引:1
泥石流是磨西河流域地质环境演化的一个重要地表过程,研究该流域内泥石流的地貌发育及演化特征可为磨西河流域第四纪以来地质环境的演变提供重要信息。通过对流域51条泥石流沟地貌形态的统计分析发现,磨西河流域内泥石流的分布在空间上表现出明显的不均性,流域内泥石流沟的数量与对应的主沟长度、主沟纵比降及流域面积之间存在着明显的分形现象,具有较高的自相似性。结果表明,泥石流沟谷形态的非线性演化特征及现象是对磨西河流域冰川环境和地质构造环境响应的直接结果,主要体现在现代冰川对流域的强烈侵蚀和贡嘎山隆升而导致流域的强烈下切。研究结果可为流域内泥石流灾害的形成机理、防灾减灾及流域环境演化提供理论依据。 相似文献
69.
This paper concentrates on considering the down/up crossing property of weighted Markov collision processes. The joint probability generating function of down crossing and up crossing numbers of weighted Markov collision processes until its extinction are obtained by constructing and studying a related multi-dimensional Markov chain. Hence, the joint probability distribution of down crossing and up crossing numbers and the mean numbers are obtained. 相似文献
70.
Diwaker 《Molecular physics》2013,111(18):2197-2203
We give a general method for finding an exact analytical solution for the two state curve crossing problem. The solution requires the knowledge of the Green's function for the motion on the uncoupled potentials. We use the method to find the solution of the problem in the case of parabolic potentials coupled by Gaussian interaction. Our method is applied to this model system to calculate the effect of curve crossing on the electronic absorption spectrum and the resonance Raman excitation profile. 相似文献