企业开展矿山修复业务的几点思考

目前,中国矿山生态修复中存在诸多历史遗留问题。国家着手推动矿山治理和生态修复,已经取得了一些成效,但仍存在资金需求缺口大,修复后矿山土地使用确权、土地流转、开发利用等方面的问题。从国家政策支持、治理资金出资模式等方面对矿山修复进行了思考。     

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.     

英国输电过网费定价机制分析

输电定价是电力市场中的关键环节,也是我国当前电力市场改革的重要任务。对英国的输电过网费形成机制进行了深入的研究。对相关的模型进行了介绍,对过网费的组成、过网费在发电机和负荷之间的分摊、参考节点的选择及修正常数的影响等问题进行了深入的分析。利用IEEE 14节点标准系统算例对参考节点的选取问题进行了分析,利用7节点算例对英国输电过网费定价机制引导发电机和负荷投资的有效性进行了分析。英国输电过网费的定价机制可以为发电和用户投资提供较好的经济信息,且分区定价方法灵活,可为我国输配电定价提供借鉴。     

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.