UNIFAC和PRSV养成方程相结合预测汽─液相平衡

本文用Ｗｏｎｇ和Ｓａｎｄｌｅｒ的混合规则，ＰＲＳＶ立方型状态方程与ＵＮＩＦＡＣ活度系数模型相结合，对３６种物质组成的５０个二元体系的汽－液相平衡进行了预测，并与实验数据作了比较，考察了２３８０个实验点，汽相组成的平均偏差是０．０１６７，压力的平均偏差是３．７３％。结果表明这种处理方法能在较宽的温度、压力范围内预测各类物系的相平衡行为，为工程计算带来很大的方便。     

New insight into prediction of phase behavior of natural gas hydrate by different cubic equations of state coupled with various mixing rules

Progress in hydrate thermodynamic study necessitates robust and fast models to be incorporated in reservoir simulation softwares. However, numerous models presented in the literature makes selection of the best,proper predictive model a cumbersome task. It is of industrial interest to make use of cubic equations of state(EOS) for modeling hydrate equilibria. In this regard, this study focuses on evaluation of three common EOSs including Peng–Robinson, Soave–Redlich–Kwong and Valderrama–Patel–Teja coupled with van der Waals and Platteeuw theory to predict hydrate P–T equilibrium of a real natural gas sample. Each EOS was accompanied with three mixing rules, including van der Waals(vd W),Avlonitis non-density dependent(ANDD) and general nonquadratic(GNQ). The prediction of cubic EOSs was in sufficient agreement with experimental data and with overall AARD% of less than unity. In addition, PR plus ANDD proved to be the most accurate model in this study for prediction of hydrate equilibria with AARD% of 0.166.It was observed that the accuracy of cubic EOSs studied in this paper depends on mixing rule coupled with them,especially at high-pressure conditions. Lastly, the present study does not include any adjustable parameter to be correlated with hydrate phase equilibrium data.     

Food safety pre-warning system based on data mining for a sustainable food supply chain

In recent years, the food safety incidents happened frequently in china, and then the problems related to food quality and safety have attracted more and more social attention. Considering the concern with regard to quality sustainability in food supply chain, many companies have developed a real time data monitoring system to ensure products quality in the supply chain network. In this paper, we proposed a food safety pre-warning system, adopting association rule mining and Internet of Things technology, to timely monitor all the detection data of the whole supply chain and automatically pre-warn. The aim of pre-warning system is to help managers in food manufacturing firm to find food safety risk in advance, and to give some decision support information to maintain the quality and safety of food products. A case study of a dairy producer was conducted, and the results showed that the proposed pre-warning system can effectively identify safety risks and accurately determine whether a warning should be issued, depending on the expert analysis when an abnormality is detected by the system. In addition, implications of the proposed approach were discussed, and suggestions for future work were outlined.     

基于GDT的对FOIL系统的改进

为了能更有效地处理含有噪音数据的数据集,提出了一个基于GDT(general distribution table)的对FOIL系统的改进方法,该方法利用GDT的思想、规则强度等概念,考虑到数据由噪音引起的不确定性.通过对FOIL系统算法的改进,能够很好地解决FOIL系统对含有噪音训练例集的学习能力,提高FOIL的学习精度.同时,通过例子阐述了该方法的实施过程,分析表明:该算法是一种新的有效地处理含有噪音数据的一阶谓词学习系统.     

Optimizing frequent time-window selection for association rules mining in a temporal database using a variable neighbourhood search

In this study, we investigate the problem of maximum frequent time-window selection (MFTWS) that appears in the process of discovering association rules time-windows (ARTW). We formulate the problem as a mathematical model using integer programming that is a typical combination problem with a solution space exponentially related to the problem size. A variable neighbourhood search (VNS) algorithm is developed to solve the problem with near-optimal solutions. Computational experiments are performed to test the VNS algorithm against a benchmark problem set. The results show that the VNS algorithm is an effective approach for solving the MTFWS problem, capable of discovering many large-one frequent itemset with time-windows (FITW) with a larger time-coverage rate than the lower bounds, thus laying a good foundation for mining ARTW.     

连铸机后部辊道防铸坯跑偏优化改造

针对连铸机后部辊道铸坯经常出现跑偏问题进行了分析,造成铸坯跑偏的主要原因为:一切至二切之间辊道辊子使用年限长,磨损严重,铸坯在辊道上行进时两侧所受线速度不同,易发生跑偏,给二切割带来诸多不便。为了防止铸坯发生跑偏,提高二切割效率,对一切辊道和二切辊道进行优化改造,分别增加了导向装置和定位装置。通过现场使用证明,这次改造杜绝了铸坯跑偏现象,提高了成材率。     

A general n-fractal aperiodic zone plate

We propose a general n-fractal aperiodic zone plate generating a beam with the first-order foci with more chosen positions. The construction method of the general n-fractal aperiodic zone plate can apply to many aperiodic zone plates, e.g. fractal, Thue-Morse and Fibonacci zone plates, and the general n-fractal aperiodic zone plates can generate more adjustable first-order foci. Parameters of the n-fractal aperiodic zone plate such as the substitution rule and the fractal order are examined and found not to affect the fractal distribution of the first-order foci. The more adjustable first-order foci generated by the general n-fractal aperiodic zone plate have been verified with both simulations and experiments.     

Decay Heat Calculations Based on Theoretical Estimation of Average Beta- and Gamma-Energies Released from Short-Lived Fission Products

Fission product decay heat of ²³⁵U was calculated for short cooling-time on the basis of a preliminary version of a new decay data library recently completed by the Japanese Nuclear Data Committee. It was shown that a full adoption of recent publications of decay schemes to derive average energies of β- and γ-rays, ē_β, and ē_γ, leads to a large underestimation of the γ-ray component of the decay heat and to an overestimation of the β-ray component. In order to remedy this, theoretical values of ē_β and ē_γ were introduced for high Q-value decays, which were obtained with a gross theory of β-decay. It improved remarkably the agreement between calculation and experiment not only for the ²³⁵U decay heat but for ²³⁹Pu and ²⁴¹Pu as well. It was concluded that a large part of decay schemes recently published for high Q-value nuclides are inappropriate to use in calculations of ē_β and ē_γ, because they fail to reproduce the effect of β- strengths at high excitations, which makes ē_β small and ē_γ large. The use of the gross theory introduces this effect correctly into the values of ē_β and ē_γ and, hence, leads to a quite good prediction of both β- and γ-ray components of the decay heat.     

电火花强化工艺制造金刚石镀层实验研究

为实现金刚石工具的快速制造和在线快速修复,探索了一种简单快速的金刚石表面强化工艺方法的可行性。以金刚石颗粒和钴颗粒为主要成分,采用压制工艺制作电极,并用该电极在基体材料304不锈钢板上进行电火花强化实验,探究电极的压制压力、金刚石含量、加工电流和加工时间等参数对实验效果的影响规律。用镀钛金刚石电极加工5 min,可得到表面上金刚石颗粒的表面积分数为13.5%、厚度为400μm的强化层,且该强化层具有很好的磨削性能。