Simple computing of the viscosity of water–dioxane mixtures,according to a fluctuating SPC/E‐Ih interstitial model

In this contribution, we propose a new simple and fast computing approach to model liquid water and water‐1,4 dioxane mixture, which is intermediate between molecular dynamics calculation and lattice fluid H‐bonding theory in which water molecules are arranged according to a fluctuating hexagonal I_h network. It generalizes the interstitial mixture models of Samoilov and Pauling by increasing the number of spatial configurations into the space of phases due to the addition of rotations and vibrations of the molecules around their equilibrium positions. The potential energy landscape is determined by the generalization of the Madelung's approach to the molecular water network using simple point charge model (SPC/E partial charges). This approach allows useful predictions as the possibility of incorporation of a molecule of dioxane in the water I_h‐network or how some cooperative dynamic jumps (site ‐ hole) of water molecules, contribute to lower Eyring's activation energies and thus to facilitate the viscous flow. © 2017 Wiley Periodicals, Inc.     

Mapping from a fragile glass-forming system to a simpler one near their glass transitions

Extensive molecular-dynamics simulations on two different glass-forming systems are performed to test the prediction proposed recently by the mean-field theory (MFT) of glass transition that a fragile system can be mimicked by a simpler one near their glass transitions. One is a simulation for a hard-sphere fluid with size polydispersity where the volume fraction φ is a control parameter and the other is for a Lennard-Jones binary mixture where the inverse temperature 1/T is a control parameter. Then, their mean-square displacements are fully analyzed by MFT. Thus, we show that both results are collapsed on a master curve given by MFT when , where is a long-time self-diffusion coefficient. We also investigate the non-singular behavior of consistently from a unified standpoint based on MFT. Thus, we show that macroscopic physical quantities in a fragile system can be transformed into those in a simpler one through a universal parameter .     

A Locally Both Leptokurtic and Fat-Tailed Distribution with Application in a Bayesian Stochastic Volatility Model

In the paper, we begin with introducing a novel scale mixture of normal distribution such that its leptokurticity and fat-tailedness are only local, with this “locality” being separately controlled by two censoring parameters. This new, locally leptokurtic and fat-tailed (LLFT) distribution makes a viable alternative for other, globally leptokurtic, fat-tailed and symmetric distributions, typically entertained in financial volatility modelling. Then, we incorporate the LLFT distribution into a basic stochastic volatility (SV) model to yield a flexible alternative for common heavy-tailed SV models. For the resulting LLFT-SV model, we develop a Bayesian statistical framework and effective MCMC methods to enable posterior sampling of the parameters and latent variables. Empirical results indicate the validity of the LLFT-SV specification for modelling both “non-standard” financial time series with repeating zero returns, as well as more “typical” data on the S&P 500 and DAX indices. For the former, the LLFT-SV model is also shown to markedly outperform a common, globally heavy-tailed, t-SV alternative in terms of density forecasting. Applications of the proposed distribution in more advanced SV models seem to be easily attainable.     

靶丸内混合气体的质谱法测量技术

 叙述了四极质谱(QMS)的结构和气体分析质谱(GAM)的定量分析工作原理。四极质谱具有快速扫描响应,较高的响应灵敏度的特点,在经过标准气体校准后,加上独特的气体进样系统,可用于惯性约束聚变(ICF)靶丸内混合气体组分含量及总量的定量分析。同时,在经过坐标尺度放大等手段,可以对混合气体中质量数极为接近的氘(4.028 2)和氦(4.002 6)在高分辨模式下进行基线分离。用四极质谱对各种靶丸结构、不同混合气体种类的气体进行了定量组分分析,为ICF实验用靶提供了同批次实验数据。     

新型反式十氢萘类液晶的合成

反式十氢萘液晶是一种结构新颖、性能优越的TFT型显示材料.文中以1-[(2‘-正烷基)-6’-反式十氢萘基]-4-环己酮为原料,经格氏试剂与羰基的加成、脱水、还原及异构化合成系列反式十氢萘类单体液晶1～13,产率22.8％～71.0％.结构分别经过IR,^1H NMR,^13C NMR,MS鉴定.详细测试了每个化合物的DSC分析数据,据此探讨了化合物在混合液晶中的相变行为.     

改性壳聚糖膜用于醇水混合液分离的研究(Ⅱ)─壳聚糖－羧甲基纤维素共混物膜

制备了壳聚糖(CS)─羧甲基纤维素(CMC)共混物膜(I-2),对其成膜反应、溶胀度、交联度及拉伸强度进行了研究,结果表明,壳聚糖与羧甲基纤维素共混物在成膜的同时还发生交联反应;当CS/CMC=1时,交联度最大,此时共混物膜不溶于稀醋酸水溶液。首次将此共混物膜用于乙醇/水混合液的分离,该膜具有优良的醇水分离性能,当CS/CMC=1时,渗透通量和分离因子皆达到最大值[J=0.9kg/(m²·h),a=800,90wt%乙醇,45℃],且该膜的分离因子基本上不随温度变化,醇水透过I-2膜的表现活化能△E为32.6kJ/mol.对CS/CMC2+2+2+2+次序递增,分离因子变化次序则刚好相反。     

A semi-analytical method for structure-internal liquid interaction problems

A composite structure-internal liquid element is proposed in this paper. Through the use of analytical functions in two orthogonal directions, the three-dimensional problem of coupled structure-internal liquid vibration is reduced to a one-dimensional one, resulting in a drastic reduction in computing efforts.Cylindrical and conical frastum composite elements are proposed to suit different problems, and examples are presented to demonstrate the accuracy of the method.     

The stokes flow from half-space into semi-infinite circular cylinder

The infinite-series solutions for the creeping motion of a viscous incompressible fluid from half-space into semi-infinite circular cylinder are presented. The results show that inside the cylinder beyond a distance equal to 0.5 times the radius of the tube from the pore opening, the deviation of the velocity profile from Poiseuille flow is less than 1%. The inlet length in this case is comparable to that computed for a finite circular cylinder pore by Dagan et al.^[1]. In the half-space outside the cylinder pore region, the flow is strongly affected by the wall. Beyond one radius of the tube from the orifice, the solutions match almost exactly the flow through an orifice of zero thickness given by Sampson^[2]. The relationship between the pressure drop and the volumetric flow rate is also computed in the present paper for the semi-infinite tube.     

三唑磷和多效唑及其混合对中华大蟾蜍蝌蚪的急性毒性

测定了三唑磷、多效唑及其混合液对中华大蟾蜍蝌蚪的急性毒性,并进行了安全性评价。试验结果表明：蝌蚪对三唑磷的24、48、72、和96h LG50分别为5．57、5．09、5．09和5．09mg／L。蝌蚪对多效唑的24、48、和72h LC50分别为60．12、40．50和34．32mg／L。蝌蚪对浓度比1：10混合液的24和48h的LG50分别为2．19（三唑磷）／21．88mg／L（多效唑）和1．84（三唑磷）／18．41mg／L（多效唑）。三唑磷和多效唑的混合物在24和48h时都表现为协同作用。     

基于多种控制机理的湍流爆炸燃烧模型研究

本文针对狭长受限空间油气爆炸燃烧发生、发展过程特点,建立不同控制机理制约不同反应步的分步反应湍流燃烧模型。该燃烧模型的基本思想在于将化学反应分为两步进行,各步的控制机理不同,各步释放的能量也不同．采用分解、混合、反应的分步方式来模拟油气爆炸燃烧过程,通过实验和数值计算结果表明,该模型能较好解决湍流爆炸燃烧过程的数值模拟问题,其结果与实验吻合很好。