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31.
Rotational viscosity of a liquid crystal mixture: a fully atomistic molecular dynamics study 下载免费PDF全文
Fully atomistic molecular dynamics (MD) simulations at 293, 303 and
313~K have been performed for the four-component liquid crystal
mixture, E7, using the software package Material Studio. Order
parameters and orientational time correlation functions (TCFs) were
calculated from MD trajectories. The rotational viscosity
coefficients (RVCs) of the mixture were calculated using the
Nemtsov--Zakharov and Fialkowski methods based on
statistical-mechanical approaches. Temperature dependences of RVC
and density were discussed in detail. Reasonable agreement between
the simulated and experimental values was found. 相似文献
32.
Jõgi Henna 《Annals of the Institute of Statistical Mathematics》1985,37(1):235-240
Summary Suppose thatH is a mixture of distributions for a given familyF A necessary and sufficient condition is obtained under whichH is, in fact, a finite mixture. An estimator of the number of distributions constituting the mixture is proposed assuming
that the mixture is finite and its asymptotic properties are investigated. 相似文献
33.
34.
Phase behaviors in a binary mixture of diblock copolymers confined between two parallel walls 下载免费PDF全文
The phase behaviors in a binary mixture of diblock copolymers confined between two parallel walls are investigated by using a cell dynamics simulation of the time-dependent Ginzburg-Landau theory.The morphological dependence of the wall-block interaction and the distance between walls(confinement degree) has been systematically studied,and the effect of repulsive interactions between different monomers is also discussed.It is interesting that multiple novel morphological transitions are observed by changing these factors,and various multilayered sandwich structures are formed in the mixture.Furthermore,the parametric dependence and physical reasons for the microdomain growth and orientational order transitions are discussed.From the simulation,we find that much richer morphologies can form in a binary mixture of diblock copolymers than those in a pure diblock copolymer.Our results provide an insight into the phase behaviors under parallel wall confinement and may provide guidance for experimentalists.This model system can also give a simple way to realize orientational order transition in soft materials through confinement. 相似文献
35.
金融市场或股票之间的相关关系变化灵活多样,针对现实中往往需要考虑的是多个市场、股票的结构,采用Mixture-Copula模型来分析多元市场的相关性结构,进而构建了Multivariate-GARCH-Mixture-Copula,模型,并选取2002年1月1日至2011年12月31日上证工业指数、商业指数、地产指数三个行业指数序列的2425组数据利用该模型进行实证分析.分析表明,Multivariate-GARCH-Mixture-Copula模型能有效地应用于实际金融市场潜在结构的分析,对投资组合的风险研究有一定的参考意义. 相似文献
36.
D. Nuzillard S. Bourg J.-M. Nuzillard 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1998,133(2):358-363
The concept of blind source separation is described and examples of its use in 1D and 2D NMR spectroscopy are presented. The goal of this data processing method is to extract the spectra of components molecules when only mixtures are available. 相似文献
37.
本文采用RNG k-ε湍流模型对超临界CO2/DME(二甲醚)二元混合工质在竖直圆管内的传热特性进行了数值模拟研究。管径4 mm,管长为1000 mm;CO2/DME浓度配比分别为97/3、95/5、92/8、90/10、85/15、以及70/30;质量流速为125~200 kg·m-2.s-1;热流密度为15~30 kW.m-2,入口温度295~308 K,入口压力8~15 MPa。不同浓度配比的混合工质在各自临界压力下应用时,随着DME浓度的增加,换热系数的峰值逐渐减低,但在温度大于310 K时混合工质的换热系数会高于纯CO2。压力相同时,随着DME浓度的增大,拟临界温度升高,换热系数峰值点也随之向温度升高的方向移动。混合工质的换热系数随质量流速的增大而增大。在拟临界点前,增大热流密度及降低压力对管内传热有利,而在拟临界点之后,换热系数随热流密度的升高以及压力的降低而降低。 相似文献
38.
本文提出了一种供热温度为80~100℃的新型空气源高温热泵循环(EIHP),该循环采用非共沸混合工质R290/R600a,利用内部自复叠技术和喷射器提升循环性能。针对EIHP循环建立了相应的热力学计算模型,并与传统热泵循环(CHP)进行了对比研究。根据计算结果,当冷凝器出口温度为100℃,蒸发器出口温度从25℃下降到-10℃时,相较于CHP循环,EIHP循环的COP提高了15%~27%,压缩机压比降低了20%~46%,容积制热量提高了22%~51%。此外,本文还研究了冷凝器出口温度,工质配比等参数对循环性能的影响情况。 相似文献
39.
Dimitris Karlis Evdokia Xekalaki 《Annals of the Institute of Statistical Mathematics》1999,51(1):149-162
Poisson mixtures are usually used to describe overdispersed data. Finite Poisson mixtures are used in many practical situations where often it is of interest to determine the number of components in the mixture. Identifying how many components comprise a mixture remains a difficult problem. The likelihood ratio test (LRT) is a general statistical procedure to use. Unfortunately, a number of specific problems arise and the classical theory fails to hold. In this paper a new procedure is proposed that is based on testing whether a new component can be added to a finite Poisson mixture which eventually leads to the number of components in the mixture. It is a sequential testing procedure based on the well known LRT that utilises a resampling technique to construct the distribution of the test statistic. The application of the procedure to real data reveals some interesting features of the distribution of the test statistic. 相似文献
40.
Achieving ultracold Bose-Fermi mixture of 87Rb and 40K with dual dark magnetic-optical-trap 下载免费PDF全文
We demonstrate that dual dark magnetic-optical-traps (MOTs) have great importance in the two-species 87Rb and 40K mixture compared with dual bright MOTs. The dark MOT has a little improvement in the trapping of single-species 87Rb or 40K gases compared with bright MOT. For the case of loading two-species 87Rb and 40K simultaneously, the improvement of 40K in the dual dark MOTs is mainly from the reduction of light-assisted collision losses. The dual dark MOTs employ a pair of conical lenses to produce the hollow beam for repump laser with high efficiency. The number and density of 87Rb and 40K atoms after evaporative cooling in the hybrid magnetic trap with dark MOT loading are compared with those in bright MOT. The atoms with large number and high density make it easier to realize the quantum degenerate of Bose-Fermi mixture. 相似文献