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81.
Van Roie B Denolf K Pitsi G Thoen J 《The European physical journal. E, Soft matter》2005,16(4):361-364
We investigated the smectic-A-hexatic-B (SmA-HexB) transition in the liquid-crystal n-hexyl-4-n-pentyloxybiphenyl-4-carboxilate (65OBC) with adiabatic scanning calorimetry. We were able to prove in a direct way that this transition is indeed very weakly first order, as was already suggested in the literature. The latent heat at the transition was determined to be HL = 0.04±0.02 J/g. Our experiments confirm the high value for the heat capacity critical exponent earlier reported, yielding = 0.64±0.05. 相似文献
82.
We give a new proof (and a generalization) of recent remarkable
result by V. Totik concerning the smoothness properties of the
equilibrium measure for compact subsets of the real line and the
Green function for complement of these subsets taken with respect
to the complex plane. 相似文献
83.
In [9] we introduced the notion of equilibrium surface current JdSx on the closed C smooth surfaces in R
3 as a generalization of electric solenoid, and proved their existence. We here show an algorithm for JdSx starting from a given surface current J dSx on . 相似文献
84.
In this paper, phase transitions are investigated in speed gradient model with an on-ramp. Phase diagrams of traffic flow composed of manually driven vehicles and adaptive cruise control (ACC) vehicles are studied, respectively. The traffic flow composed of ACC vehicles is modeled by enhancing propagation speed of small disturbance. The phase diagram of traffic flow composed of manually driven vehicles is similar to that in previous works, in which such states as pinned localized cluster (PLC), moving localized cluster (MLC), triggered stop-and-go traffic (TSG), oscillatory congested traffic (OCT), and homogeneous congested traffic (HCT) are reproduced. In the phase diagram of traffic flow composed of ACC vehicles, traffic stability is enhanced and such states as PLC, MLC, and TSG disappear. Furthermore, some interesting phenomena, such as stationary OCT upstream of on-ramp and appearance of second OCT in HCT, are identified. 相似文献
85.
We present two types of Molecular Dynamics (MD) simulation for calculating the desorption rate of molecules from a surface. In the first, the molecules move freely between two surfaces, and the desorption rate is obtained either by counting the number of desorption events in a given time, or by looking at the average density of the molecules as a function of distance from the surface and then applying transition state theory (TST). In the second, the potential of mean force (PMF) for a molecule is determined as a function of distance from the surface and the desorption rate is obtained by means of TST. The methods are applied to water on the MgO(0 0 1) surface at low coverage. Classical potentials are used so that long simulations can be performed, to minimise statistical errors. The two sets of MD simulations agree well at high temperatures. The PMF method reproduces the 0 K adsorption energy of the molecule to within 5 meV, and finds that the well depth of the PMF is not linear with temperature. This implies the prefactor frequency f in the Polanyi-Wigner equation is a function of temperature, increasing at lower temperatures due to the reduction of the available configuration space associated with an adsorbed molecule compared with a free molecule. 相似文献
86.
This paper is concerned with the analysis problem for the exponential stability of a class of Cohen-Grossberg neural networks with variable and distributed delays. Some sufficient conditions ensuring the existence, uniqueness and exponential stability of the equilibrium point are obtained by employing Brouwer’s fixed-point theorem and by applying the inequality technique. In the results, we do not assume that the activation function satisfies the boundedness and the Lipschitz condition. Three numerical examples are given to show the effectiveness of the obtained results. 相似文献
87.
在Hilbert空间中引进并研究一种新的复合粘性迭代算法,借以寻求有限个平衡问题的公共解集与非扩张映象不动点集的一个公共元素.所得结果改进并推广了最近一些人的最新结果. 相似文献
88.
Salim Derrouiche 《Applied Surface Science》2007,253(13):5894-5898
The heats of adsorption at several coverages of the linear and bridged CO species (denoted L and B, respectively) adsorbed on the Pt0 sites of the 2.9 wt% Pt/10% K/Al2O3 catalyst are determined using the Adsorption Equilibrium Infrared spectroscopy method. The addition of K on 2.9% Pt/Al2O3 modifies significantly the adsorption of CO on the Pt particles: (a) the ratio L/B is decreased from 8.4 to 1, (b) a new adsorbed CO species is detected with an IR band at 1763 cm−1, (c) the heats of adsorption of L and B CO species are significantly altered and the positions of their IR bands are shifted. The heats of adsorption of L CO species are decreased: i.e. 206 and 105 kJ/mol at low coverages on Pt/Al2O3 and Pt/K/Al2O3 respectively. Two B CO species denoted B1 and B2, with different heats of adsorption are observed on Pt/K/Al2O3. The heats of adsorption of B2 CO species (major B CO species) are significantly larger than those measured in the absence of K: i.e. 94 and 160 kJ/mol at low coverages on Pt/Al2O3 and Pt/K/Al2O3 respectively, whereas those of B1 CO species (minor species) are similar: 90 kJ/mol at low coverages. These values are consistent with the qualitative High Resolution Electron Energy Loss Spectrometry literature data on Pt(1 1 1) modified by potassium. 相似文献
89.
90.
Two-component thermo-responsive hydrogels poly(N-isopropylacrylamide)-co-vinylbenzyltrimethylammonium chloride (NIPA-co-VBT) and poly(N-isopropylacrylamide)-co-p-sodium styrene sulphonate (NIPA-co-SSS) were prepared by using high energy gamma radiation. The gels were characterized by Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and sol-gel analysis. The presence of ionic monomers in NIPA leads to lower gel content. Introduction of ionic components in the matrix enhanced swelling extent but caused slower volume transition. The swelling studies in alcohol indicated that swelling extent was function of polarity of the swelling medium and all gels followed the order water > methanol > ethanol > iso-propanol. In mixed co-solvents (water-alcohol), they exhibit complex reentrant behavior. The co-polymer gels containing VBT swelled faster and to higher extent than those containing SSS. The dynamic swelling studies indicated that diffusion of water in PNIPA gel shifts from Fickian for PNIPA to anomalous for NIPA-co-ionic gels also the mean swelling time (MST) decreases for gels containing ionic monomers. 相似文献