润滑油溶解对混合工质组分浓度改变的实验研究

建立了气液溶解平衡实验装置,研究润滑油溶解对低温混合工质浓度的改变。采用商用矿物润滑油3GS对2组混合工质进行了实验研究,实验温度范围为36～100℃,压力范围为157.1～832.6kPa.实验结果表明:由于润滑油的溶解,混合工质浓度改变明显,第一组混合工质中组分最大相对浓度改变率为-40.32%,第二组混合工质中组分最大相对浓度改变率为24.54%.和初始浓度相比,浓度变化趋势为高沸点烷烃浓度减少,低沸点烷烃(或氮气)浓度升高.     

Inequalities between some large deviation rates

In some cases it is interesting to have inequalities between asymptotic rates. Here, we consider asymptotic rates in the fashion of large deviations. We present inequalities between large deviation rate functions for telegrapher processes in the first part, and inequalities between Lundberg parameters for Markov‐additive processes in the second part. Copyright © 2007 John Wiley & Sons, Ltd.     

Action mechanism of antioxidation and anticorrosion and molecular design for perfluoropolyether fluid additives (II)

Three kinds of the antioxidation and anticorrosion additives from the N-substituted perfluoropolyalkylether phenylamide (PFPEA) were selected and synthesized. UV and IR spectral analyses were carried out, and strong absorption peaks of UV from benzene ring are about 240.7, 215.4 and 230.1 nm, respectively. The characteristic peaks of IR from the C=O are about 1713.9, 1712.2 and 1710.8 cm^-1, respectively. The antioxidant and anticorrosive property was tested for the three synthesized additives. The results show that the weight loss of lubrication oil can decrease by 1/7, 1/9 and 1/25 respectively after adding synthesized additives. The thermal decomposition temperature(T_D) in the presence of Al₂O₃ can increase by 19–22°C. From theoretic and experimental study it indicates that the PFPEAs with nitrogen heteroatom not only accepts electron from perfluoropolyalkylether oxygen radical (R_fO.) to form a stable adduct and to prevent RfO. decomposing further, but also donates electron to form chemical adsorption film and to protect metal from corrosion. These additives have shown the better property of the antioxidation and anticorrosion. An electron-releasing group, or phenyl group, introduced to the N-atom of this kind of compound can improve the antioxidant and anticorrosive efficiency of the additives.     

An explicit norm representation for the analysis of multilevel methods

In the present paper we develop a representation of a norm frequently used in the analysis of multilevel methods. This allows us to examine the convergence of additive Schwarz schemes also in the case of non-nested subspaces. We demonstrate the usefulness of the given norm representation by studying in detail the stability of sparse grid splittings due to Griebel and Oswald, which turns out to be a special case of our unified theory. Further applications concerning approximation spaces and non-nested finite element spaces are given. This revised version was published online in August 2006 with corrections to the Cover Date.     

Using hydrophobic additive as pore‐forming agent to prepare macroporous PNIPAAm hydrogels

Hydrophobic poly(lactic acid) nanospheres were fabricated and used as an additive during the polymerization and gelation process of temperature‐sensitive poly(N‐isopropylacrylamide) (PNIPAAm) hydrogels. The influence of hydrophobic additive on properties of PNIPAAm hydrogels was examined. The interior morphology studied by scanning electron microscopy revealed that the hydrophobic additive induced a macroporous structure in the resulting PNIPAAm hydrogels. Results demonstrate that the hydrophobic additive acts as a pore‐forming agent like conventionally used hydrophilic additive does during the gelation process. Because of the macroporous network and incorporated additives, the temperature‐sensitive characteristics, particularly the equilibrium swelling ratio at room temperature and shrinking rate upon temperature increase of modified PNIPAAm hydrogels, are significantly improved. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5490–5497, 2005     

Self-similar processes with independent increments associated with Lévy and Bessel processes

Wolfe (Stochastic Process. Appl. 12(3) (1982) 301) and Sato (Probab. Theory Related Fields 89(3) (1991) 285) gave two different representations of a random variable X₁ with a self-decomposable distribution in terms of processes with independent increments. This paper shows how either of these representations follows easily from the other, and makes these representations more explicit when X₁ is either a first or last passage time for a Bessel process.     

Approximation of the solution and its derivative for the singularly perturbed Black-Scholes equation with nonsmooth initial data

A problem for the black-Scholes equation that arises in financial mathematics is reduced, by a transformation of variables, to the Cauchy problem for a singularly perturbed parabolic equation with the variables x, t and a perturbation parameter ɛ, ɛ ∈ (0, 1]. This problem has several singularities such as the unbounded domain, the piecewise smooth initial function (its first-order derivative in x has a discontinuity of the first kind at the point x = 0), an interior (moving in time) layer generated by the piecewise smooth initial function for small values of the parameter ɛ, etc. In this paper, a grid approximation of the solution and its first-order derivative is studied in a finite domain including the interior layer. On a uniform mesh, using the method of additive splitting of a singularity of the interior layer type, a special difference scheme is constructed that allows us to ɛ-uniformly approximate both the solution to the boundary value problem and its first-order derivative in x with convergence orders close to 1 and 0.5, respectively. The efficiency of the constructed scheme is illustrated by numerical experiments. The text was submitted by the authors in English.     

Kinetic and activation thermodynamic parameters on thermal decomposition of synthetic lubricant oils

The kinetic and thermodynamic study of synthetic lubricant oils was accomplished in this work, using isothermal and non-isothermal thermogravimetry based on mass loss as a function of time and temperature. The thermodynamic and kinetic behavior of the synthetic lubricant oils depends on atmosphere and heating rates used in TG analysis. The kinetic and thermodynamic results were satisfactory, presenting good correlation.     

润滑油对带膨胀机CO2跨临界循环的影响

本文对PAG、POE、PAO和AB四种润滑油特性进行了分析,结果表明PAG具有较好的综合性能.又从PAG/CO2混合物的溶解性和粘温特性证明了PAG比较适合CO2跨临界循环.最后对工质CO2夹带的微量PAG对压缩机、膨胀机、气体冷却器和蒸发器的性能影响分别进行了分析,并提出了超临界换热分析模型.结果表明润滑油虽然有助于改善压缩机、膨胀机性能,但造成了换热器性能的严重下降.     

噪声之间的耦合对一维激光场的影响

本文从理论上对加性噪声和倍增噪声之间有耦合作用的一维激光模型进行了分析，求出定态时激光强度分布函数的解析形式．同噪声之间不存在耦合的激光模型相比较，噪声之间的耦合增强了激光强度的涨落．