Coiling/uncoiling behaviour of sodium polystyrenesulfonate in 2‐ethoxyethanol–water mixed solvent media as probed using viscometry

Precise measurements of the viscosities of solutions of sodium polystyrenesulfonate in water and in 2‐ethoxyethanol–water mixtures containing varying amounts of 2‐ethoxyethanol have been performed at 308.15, 313.15, 318.15 and 323.15 K. The intramolecular contributions to the reduced viscosities of the polyelectrolyte solutions were obtained through isoionic dilution maintaining the total ionic strengths of the solutions at polyelectrolyte concentrations of 0.0033, 0.0054 and 0.0080 eq L^?1 with sodium chloride. The Huggins constants were also obtained from the experimental data. The influences of the medium and the temperature on the intramolecular contributions to the reduced viscosities as well as on the Huggins constants have been interpreted from the points of view of the conformational characteristics and polyelectrolyte–solvent and polyelectrolyte–polyelectrolyte interactions prevailing in the polyelectrolyte solutions under investigation. Polyion chains were found to coil upon addition of 2‐ethoxyethanol to water or upon an increase of temperature. Thermodynamic affinities for polyelectrolyte–solvent and polyelectrolyte–polyelectrolyte interactions were found to depend greatly on the medium. © 2014 Society of Chemical Industry     

Individual finger contribution in submaximal voluntary contraction of gripping

The objective of this study was to evaluate individual finger force and contribution to a gripping force, the difference between actual and expected finger forces and subjective discomfort rating at 10 different submaximal voluntary contraction (%MVC) levels (10–100% in 10 increments). Seventy-two participants randomly exerted gripping force with a multi-finger force measurement system. The individual finger force, gripping force and discomfort increased as %MVC levels increased. The middle and ring fingers exerted more force and contributed to a gripping force more than the index and little fingers due to their larger mass fractions of the digit flexor muscles. It was apparent at <50% MVC; however, the index finger increased its contribution and exerted even more force than expected at more than 50% MVC. Subjective discomfort supported the results of the objective measures. This could explain the conflicting findings between index and ring fingers in previous finger contribution studies.

Statement of Relevance: Hand tool design is of special interest in ergonomics due to its association with musculoskeletal disorders in the hand. This study reveals a different contribution pattern of the fingers in submaximal voluntary contraction of gripping exertion.     

轨迹驱动切负荷的布点协调优化算法的简化

随着系统规模及各种不确定性的增加,轨迹驱动切负荷(TDLS)的布点优化的计算量急剧增加。综合考虑负荷模型对布点优化的计算量及精度的影响,验证在TDLS布点中采用简化负荷模型的可行性。同时,改进已有的协调优化算法。包括简化其流程,减少迭代次数,减少灵敏度系数的更新次数。仿真表明,上述简化方法对计算精度的影响并不显著,但计算量大幅降低,有利于工程实用。     

基于文献计量和内容分析的装备体系贡献研究综述

为全面客观地展现装备体系贡献的研究现状,综合运用文献计量法与内容分析法,对发文趋势和重点期刊进行描述性统计。分析核心作者、机构及其合作网络,应用2维分析框架开展实验式内容解读,通过关键词聚类与突现词检测探究知识基础与前沿热点。研究结果表明：作者合作网络比较分散,机构合作网络相对集中,数据来源以仿真试验和示例假定为主,研究方法以定量模型居多,微观层面的应用研究是当前的主流视角,装备体系贡献的研究重点呈现出“作战能力—作战效能—贡献率—体系结构”的演化路径。     

对苯二甲酸催化加氢制备1,4-环己烷二甲酸的热力学分析

采用Constantinou-Gani基团贡献法和Rozicka-Domalski基团贡献法计算了对苯二甲酸(TA)加氢制备1,4-环己烷二甲酸(CHDA)过程中可能涉及的主副产物的标准摩尔生成焓、标准摩尔蒸发焓和定压热容。在373.15~573.15 K的温度下,分别计算了TA加氢反应体系中各反应的焓变、Gibbs自由能变和平衡常数。计算结果表明,在373.15~573.15 K温度范围内,TA加氢反应以苯环加氢反应和脱羧基反应为主。TA加氢生成CHDA的反应是放热反应,低温有利于该反应的进行,而TA脱羧基生成苯甲酸的反应是吸热反应,高温有利于该反应的进行。但因低温不利于TA的溶解,综合考虑,选择TA加氢制备CHDA的反应温度为493.15~523.15 K较适宜。     

The influence of quality benefit and marginal contribution on the optimal equity structure of the PPP projects: balancing public and private benefits

Public–private partnerships (PPPs) involve many different participants, and the equity allocation between them may influence the performance of PPP projects. While the optimal capital structure and equity capital structure of the project company have been extensively investigated, few studies have examined how to allocate equity shares among different private participants. Considering both public and private benefits, this study focuses on the optimal equity structure between construction contractor (CC) and operating contractor (OC). A game model is used to analyze how quality benefit and marginal contribution of CC and OC’s effort affect the optimal equity structure. The findings reveal that the private consortium expects the party (CC or OC) with higher marginal contribution of effort to own more equity shares, while government expects the party (CC or OC) with lower marginal contribution of effort to own more equity shares. Furthermore, a non-linear relationship between the optimal equity structure and government’s bargaining power is found. The results also manifest that the quality benefit of construction on operation is a nontrivial factor when designing the equity structure. If unconsidered, the CC’s optimal equity ratio will be either undervalued (when a higher construction quality can reduce the operating cost) or overvalued (when a higher construction quality can increase the operating cost). These findings can provide some insights into designing the equity structure for PPP projects in the bidding process.     

Knowledge contribution in information system development teams: An empirical research from a social cognitive perspective

The extent of knowledge contribution is the key to the success of system development projects. Knowledge contribution refers to the knowledge that is provided to increase a team's efficiency and achieve its goal. This study proposes a research model exploring factors that influence the extent of knowledge contribution from a social cognitive perspective. These factors include the team relationship commitment, team relationship norms, and awareness of expertise location. Additionally, this study argues that a team's awareness of expertise location mediates the effects of affective commitment and relationship norms on knowledge contribution. The result shows that the awareness of expertise location plays a crucial mediating role in the relationships between the two socially prescribed motivations and knowledge contribution. Moreover, team relationship commitment has an important impact on team established relational norms.     

苯酚与异丙醇烷基化合成异丙基苯酚的热力学和动力学

基于Benson基团贡献法研究苯酚与异丙醇烷基化反应过程,确定了主、副反应的反应热、平衡常数及平衡转化率,得到反映热力学性质的反应方程式并建立反应的网络结构,为该体系的工艺设计提供热力学依据。在苯酚与异丙醇物质的量比为0.5~2.0、温度(513.15~573.15)K、空速8 h-1和催化剂颗粒(40~60)目[相当于粒径(0.45~0.30)mm]条件下进行本征动力学实验。选用幂数型动力学模型,对参数进行估值。用Runge-Kutta法进行数值积分,Simplex法对参数进行优化,F统计法对模型进行检验,最终得到能较好描述反应的本征动力学模型。     

基于声-固耦合模型的车内噪声响度参数的预测与分析研究

针对传统A计权声压级评价指标对噪声低频成分衰减较大,常常出现车内声压级达标,声品质不合格的问题。引入心理声学参数的响度参量,利用虚拟仿真技术分析评价车内声学特性。建立驾驶室声-固耦合有限元模型,结合试验激励数据,进行基于模态的声学响应计算。在Matlab平台上,建立车内声品质客观心理声学参数响度的计算模型,对比预测驾驶室内场点的声压级和响度分布,结合声压级和响度结构板块贡献量分析,研究声压级和响度参量评价驾驶室结构特性的差别并识别驾驶室主要噪声源。以此为基础指导优化驾驶室结构阻尼铺设位置,综合提高车内声学品质。     

中国产业结构变动的能源消费影响--基于灰色关联理论和面板数据计量分析

本文在利用经济增长的产业分解模型分析对经济增长贡献的基础上，以中国近20年来的数据为样本，采用灰色关联分析法分析产业结构和能源消费的关联效应，并利用面板数据计量模型进一步分析1995年以来产业内部各行业的能源消费特征，总结出：第二产业对能源消费总量的影响最大，灰关联度高速0．905，产业结构地位不断提升，对GDP增长的贡献稳步上升，中国经济的增长主要依靠能源高消耗的第二产业来拉动；一、三产业和能源消费的关联性也较高，但一产的经济贡献呈下降趋势，三产稳步不前，对经济增长的贡献有限；在产业内部，工业是能源消费能力最强的行业，行业影响因子最高。