基于文献计量的国际河流栖息地研究动态

河流栖息地是水域生态系统的重要组成部分,以Web of Science论文数据库为数据源,利用TDA等工具对2015-2017年国际河流栖息地研究进行文献计量分析。结果表明:该领域研究方向涉及环境科学与生态学、海洋与淡水生物学等多个学科;美国的发文量最高,中国居于第2位;"保护"、"河流"、"鱼类"和"气候变化"是热点关键词;当前河流栖息地研究动态集中于风险评估与生态修复、水生生物群落、外来生物入侵、栖息地的地貌变化等方面。     

NON-CUBIC EQUATION OF STATE FOR PHASE EQUILIBRIUM CALCULATIONS

A new non-cubic equation of state is proposed for calculation of the thermodynamic properties ofnonpolar and polar fluids and their mixtures,including,saturated vapor pressure,saturated liquid volume,saturated vapor volume,heats of vaporization and vapor-liquid equilibria.The new equation is derived from thegeneralized van der Waals partition function in which the repulsive terms are expressed with the Carnahan andStarling equation for hard spheres,and the attractive terms are made up of the dispersive energy and theChemical association energy. The rules of dependence of parameters α and σ and on temperature are considered broadly so that the newequation yields good agreement with experimental saturated properties of 20 nonpolar and 27 polar fluids in therange of reduced temperatures of 0.5 to 1.0 The new equation with parameters group-contributed generally givessatisfactory predictions on saturated properties. Correlations of vapor-liquid equilibrium data for alcohol-containing systems by using van d     

Reliability analysis of a repairable duplex system

We analyse the survival time of a repairable duplex system characterised by cold standby and by a pre-emptive priority rule. We allow general probability distributions for failure and repair. Moreover, an important realistic feature of the system is the general assumption that the non-priority unit has a memory. This combination of features has not been analysed in the previous literature. Our (new) methodology is based on a concatenation of a Cauchy-type integral representation of the modified Heaviside unit-step function and a two-sided stochastic inequality. Finally, we introduce a security interval related to a security level and a suitable risk-criterion based on the survival function of the system. As a practical application, we analyse some particular cases of the survival function jointly with the security interval corresponding to a security level of 90.     

A New Derivation of the Cubature Kalman Filters

This paper investigates the cubature Kalman filtering (CKF) for nonlinear dynamic systems. This third‐degree rule based filter employs a spherical‐radial cubature rule to numerically compute the integrals encountered in nonlinear filtering problems, thereby removing the requirements of explicitly computing the Jacobians. The cubature rule, however, requires computing the intractable integrals over a high‐dimensional spherical region for multidimensional applications. Moreover, the cubature formula that has been used to construct the spherical cubature formula has some demerits, most notably its inconvenient properties in computation and low estimation accuracy. Aimed at these issues, a general class of CKFs that uses only cubature rules is derived in this paper. It can be shown that the conventional CKF is a special case of the proposed algorithm. The paper also includes higher‐degree CKFs, especially two representative types of the fifth‐degree CKFs. Performance of the proposed algorithms is demonstrated via two target tracking problems. The experimental results, presented herein, illustrate the superior performance of higher‐degree CKFs to conventional nonlinear filters.     

基于情感计算的商品评论分析系统

针对电子商务中的商品评论信息过载问题,运用情感计算理论,通过挖掘商品评论信息中的商品特征及相应的情感褒贬态度,为消费者提供一个商品特征粒度上的情感分析结果,从而帮助消费者从庞杂的商品评论中快速获取有效信息。系统首先采集指定商品的评论集并挖掘商品特征,然后结合情感语料库和词汇相似度计算,利用依存关系找到特征-极性词对以及程度副词和否定词。基于以上结果,考虑程度副词的强度,以及程度副词和否定词共现语序不同造成的语义差异,提出了商品评论情感倾向程度的计算方式。最后,进行系统实现并验证算法的有效性。实验结果表明,系统具有良好的应用效果。     

基于灰熵关联分析的流水车间多目标调度优化及算法实现

求解流水车间多目标调度优化问题及算法适应度值分配问题, 结合灰色关联度分析方法及信息熵理论提出灰熵关联度适应值分配策略, 利用灰关联系数结合熵值权重计算适应度值, 以灰熵关联度值引导启发式算法进化. 将该方法应用到差分算法及遗传算法中解决三目标流水车间调度问题. 实验表明: 灰熵关联度适应值分配策略能够解决该问题, 可以得到分布均匀的Pareto 前端; 同时, 基于此策略的差分算法得到的解好于遗传算法的解.     

物联网信息模型与能力分析

虽然近几年物联网技术开发与应用快速增长,但物联网理论研究仍然处于发展阶段.物联网作为一个典型的信息与通信系统,不仅具有现有互联网的信息存储和传递的能力,而且具有物品信息的自动采集和处理能力.构建物联网信息模型是分析物联网特征能力的一种有效方法.根据国际电信联盟有关物联网的定义和特征描述,通过采用统一建模语言构建物联网信息模型,分析和验证了物联网的物品相关能力、自主操作能力以及隐私保护能力,讨论了物联网信息模型在物联网技术标准方面的指导性结论,分析了物联网信息模型在讨论有争议的物联网概念或观点方面的应用价值.     

Integral approximation—an approach to reduced models for particulate processes

In this contribution, a model reduction technique for population balance systems describing particulate processes is presented. This technique is based on integral approximation and allows the derivation of highly accurate moment models. In contrast to other model reduction methods which can be found in literature, this integral approximation technique can be applied for arbitrarily complex phenomena specifications. The applicability of the presented method will be demonstrated for different example processes by comparing the dynamic behavior of the original population balance models with those of the derived reduced models of moments.     

无线传感器网络不确定数据PT-Top k查询处理技术

在无线传感器网络现实应用中,感知数据普遍存在不确定性。由于不确定数据引入了概率维度,使得不确定数据查询种类更加丰富,同时也给查询处理带来困难。不确定数据Top-k查询是一个典型的不确定数据查询任务。考虑到无线传感器网络查询处理技术对查询响应时间和网络通信消耗的高要求,研究了面向层次聚簇结构的无线传感器网络不确定数据Top-k查询处理技术。通过分析不确定数据特点,基于x-tuple规则元组模型,采用簇内与簇间的两阶段数据查询处理机制,提出了基于Poisson分布的分布式不确定数据PT-Top k查询处理近似算法TPQP。通过实验,从总体通信消耗、与概率阈值p相关分析、与排序数k相关分析以及数据敏感度分析等方面,说明了TPQP算法在通信消耗、查询响应时间上的优越性。     

Study of the High‐Pressure Vapour‐Liquid Equilibria for Strongly Non‐ideal Binary and Ternary Mixtures

High‐pressure vapour‐liquid equilibria for binary and ternary high polar and asymmetric systems are calculated using the Peng‐Robinson‐Stryjek‐Vera equation of state coupled with the Twu‐Coon (TWMR), the Orbey‐Sandler (OSMR) and the Wong‐Sandler (WSMR) mixing rules. Modified UNIFAC model is used for determining the activity coefficient and excess Gibbs free energy. The calculated results are compared with the experimental data and good agreement is observed. The average absolute deviation percents (AAD%)s indicated that the WSMR has less AAD% than other mixing rules in most of cases.