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121.
Denote by *
n
the set of all k
*-cycle resonant hexagonal chains with n hexagons. For any B
n
*
n
, let m(B
n
) and i(B
n
) be the numbers of matchings (=the Hosoya index) and the number of independent sets (=the Merrifield–Simmons index) of B
n
, respectively. In this paper, we give a characterization of the k
*-cycle resonant hexagonal chains, and show that for any B
n
*
n
, m(H
n
)m(B
n
) and i(H
n
)i(B
n
), where H
n
is the helicene chain. Moreover, equalities hold only if B
n
=H
n
. 相似文献
122.
Vesselin Dimitrov 《Journal of solid state chemistry》2005,178(3):831-846
A classification of binary oxide glasses has been proposed taking into account the values obtained on their refractive index-based oxide ion polarizability αO2−(n0), optical basicity Λ(n0), metallization criterion M(n0), interaction parameter A(n0), and ion's effective charges as well as O1s and metal binding energies determined by XPS. Four groups of oxide glasses have been established: glasses formed by two glass-forming acidic oxides; glasses formed by glass-forming acidic oxide and modifier's basic oxide; glasses formed by glass-forming acidic and conditional glass-forming basic oxide; glasses formed by two basic oxides. The role of electronic ion polarizability in chemical bonding of oxide glasses has been also estimated. Good agreement has been found with the previous results concerning classification of simple oxides. The results obtained probably provide good basis for prediction of type of bonding in oxide glasses on the basis of refractive index as well as for prediction of new nonlinear optical materials. 相似文献
123.
建立了处理双原子分子-表面相互作用的推广的LEPS势.借助推广的LEPS势,系统研究了一氧化碳分子在铂低指数表面吸附的动力学特性,重现了低指数表面的分子吸附热、吸附几何及本征振动等实验数据;鉴定了某些不合理的文献信息,预测了实验尚未探测到的重要信息:预测到Pt(100)表面四重洞位的C-O伸缩振动频率为1 962.60 cm-1;预测到Pt(110)表面吸附态的C-O及C-Pt键长分别为115.1、147 pm. 相似文献
124.
A. Voelkel 《Chromatographia》1987,23(3):195-198
Summary The possibility of evaluation of the parameters representing the dispersive solute-solvent interactions is presented. BN and Bs values can be used to describe the liquid phase polarity and to predict the retention indices of alcohols when the model
polyxyethylene glycol dialkyl ethers and their sulphur analogs are used as stationary phases. The possibility of the first
ionization potentials estimation is also presented. 相似文献
125.
Zusammenfassung In der vorliegenden Arbeit wird eine Methode zur Retentionsindex-Bestimmung beschrieben, die von einem kubischen Zusammenhang zwischen Bruttoretentionszeit-Differenzen der Referenzhomologen und der Kohlenstoffzahl ausgeht. Hieraus ergeben sich direkt die Nettoretentionszeiten. Der Fehler der Totzeitbestimmung entfällt bei dieser Methode. Mit den so gewonnenen Nettoretentionszeiten erhält man über einen kubischen Zusammenhang zwischen 1g ts=f(C) die Retentionsindices. Extrapolationen und Interpolationen sind über 300 Retentionsindexeinheiten mit einem mittleren Fehler von ±0,02 Retentionsindexeinheiten möglich. Das Verfahren bietet sich für eine automatische Berechnung der I-Werte mittels on-line-Datenverarbeitung an.
Cubic calculation of retention indices without determining the dead-time tm
Summary The method for the calculation of retention indices described here is based on a third order relationship between the logarithm of differences of unadjusted retention times of homologues and the carbon number. From this adjusted retention times are directly calculated. A determination of the dead-time is not necessary thus avoiding the errors connected with this factor. A cubic equation for the logarithm of the adjusted retention time lg ts as a function of carbon number Cn is used for the retention index calculation. Extrapolations and interpolations can be done over a range of 300 index units with an average deviation of ±0.02 i.u.. The method offers the possibility of an automated on-line calculation of retention indices by computer merely on the basis of unadjusted retention times.相似文献
126.
Summary The separation of C1–C4 alkyl tert-butyl ethers with the general formula (CH3)3C–O–R (R-alkyl substituent) on fused-silica capillary columns coated with dimethylsilicone and cyanopropylmethylsilicone stationary phases was investigated. Retention indices were determined at two temperatures in order to understand their chromatographic behaviour. The respective standard deviations were 0.3 and 0.5 i.u. 相似文献
127.
基于构建的数字经济发展水平评价指标体系与2010~2018年全国30个省市(除西藏、港澳台)的面板数据,对中国数字经济发展水平的时空特征、动态演化与区域差异原因进行探究。研究发现:全国及三大区域的数字经济发展水平均呈现稳步上升态势,并伴有明显的空间相关性、空间集聚性和区域差异性,且东部相较于中西部区域内差异更大。数字经济发展速度动态演化显示,整体上中国各省市数字化发展水平变化速度状态表现为上升趋势,相较于中西部,东部拥有更大的速度变化状态。地区前期数字化基础、经济发展的一阶滞后、政府科技投入均会促进区域数字经济的发展,对外开放水平会抑制数字经济发展,地区规模对数字经济的影响表现为非线性。此外,不同线性影响因素在不同区域内对数字经济发展水平具有不同的影响力。 相似文献
128.
Ruggero Freddi 《分析论及其应用》2022,38(1):26-78
In this paper we consider the Dirichlet problemwhere $\rho$ is a small parameter and $\Omega$ is a $C^2$ bounded domain in $\mathbb{R}^2$. In [1], the author proves the existence of a $m$-point blow-up solution $u_\rho$ jointly with its asymptotic behaviour. We compute the Morse index of $u_\rho$ in terms of the Morse index of the associated Hamilton function of this problem. In addition, we give an asymptotic estimate for the first $4m$ eigenvalues and eigenfunctions. 相似文献
129.
General Stochastic Hybrid System (SHS) are characterised by Stochastic Differential Equations (SDEs) with discontinuities and Poisson jump processes. SHS are useful in model based design of Cyber-Physical System (CPS) controllers under uncertainty. Industry standard model based design tools such as Simulink/Stateflow® are inefficient when simulating, testing, and validating SHS, because of dependence on fixed-step Euler–Maruyama (EM) integration and discontinuity detection. We present a novel efficient adaptive step-size simulation/integration technique for general SHSs modelled as a network of Stochastic Hybrid Automatons (SHAs). We propose a simulation algorithm where each SHA in the network executes synchronously with the other, at an integration step-size computed using adaptive step-size integration. Ito’ multi-dimensional lemma and the inverse sampling theorem are leveraged to compute the integration step-size by making the SDEs and Poisson jump rate integration dependent upon discontinuities. Existence and convergence analysis along with experimental results show that the proposed technique is substantially faster than Simulink/Stateflow®when simulating general SHSs. 相似文献
130.
This paper is concerned with windshear detection in connection with real-time wind identification (Ref. 1). It presents a comparative evaluation of two techniques, one based on the shear/downdraft factor and one based on the wind difference index. The comparison is done with reference to a particular microburst, that which caused the 1985 crash of Flight Delta 191 at Dallas-Fort Worth International Airport.The shear/downdraft factor has the merit of combining the effects of the shear and the downdraft into a single entity. However, its effectiveness is hampered by the fact that, in a real situation, the windshear is accompanied by free-stream turbulence, which tends to blur the resulting signal. In turn, this results in undesirable nuisance warnings if the magnitude of the shear factor due to free-stream turbulence is temporarily larger than that due to true windshear. Therefore, proper filtering is necessary prior to using the shear/downdraft factor in detection and guidance. One effective way for achieving this goal is to average the shear/downdraft factor over a specified time interval . The effect of on the average shear/downdraft factor is studied. 相似文献