世界一流科技社团发展现状国际比较——基于实践动态的视角

 以世界一流科技社团2019年9月-2020年6月的新闻数据，分析总结了世界一流科技社团的实践动态及发展规律。研究发现：（1）国内科技社团强调党建引领，制度优势体现出强大的凝聚力；（2）国外科技社团更加善于聚合公共资源，并将产生的新知识转化为可供应用的产品和服务，推进科技与经济、创新链与产业链的融合；（3）国外科技社团善于通过多种形式发声，充分发挥决策者智库咨询的作用；（4）全球科技治理的实质性活动由国际化大型科技社团主导。中国科技社团需要重视决策咨询智库建设、为政府重大决策制定提供技术支撑；完善学术交流平台、创造有利于科技工作者的良好生态；为科技经济融合贡献智慧，推动互惠共享的国际科技交流合作。     

山西锦生润票号衰败考论

锦生润票号诞生在光绪二十九年,恰逢山西票号鼎盛时代,然而,也是山西票号"危机四伏"、衰败初露端倪的时期.锦生润票号于民国六年冬月主动"收歇",自有特别的"个案"的原因:锦生润不是完全意义上的山西票号,与经营了百年之久的其它票号不能简单地相提并论,仅仅是晚清山西商人开设"账局"的发展和延续,或者是"账局"与专业化汇兑的"票号"的有机结合的"蓝本",属于一种新类型的票号.锦生润票号的衰败及其原因,也是票号发展历史阶段的一个极其重要的组成部分.     

Multifunctional artificial nacre via biomimetic matrix-directed mineralization

Natural nacre, one of the most studied biological structural materials with delicate hierarchical structures and extraordinary performance, has inspired the design and fabrication of artificial structural ceramics with high fracture toughness. However, to meet the diverse requirements of different applications, future structural materials must be multifunctional with superior mechanical properties, such as strength, hardness, and toughness. Herein, based on the matrix-directed mineralization method for producing biomimetic structural materials, we introduce nanoparticles with different inherent functions into the platelets of artificial nacre via the co-mineralization of aragonite and the nanoparticles. Besides their enhanced mechanical properties, the obtained artificial nacre materials also exhibit different functions depending on the type of the nanoparticles. To extend the versatility of this strategy, the effects of nanoparticles of different sizes and zeta potentials on mineralization are also analyzed. This universal strategy can be applied to the fabrication of other types of functionalized biomimetic structural ceramics that have potential applications in various fields, such as biomedical science.     

Comparison of Travel Mode Choice Between Taxi and Subway Regarding Traveling Convenience

In this study, we investigate travel mode choice behavior between taxi and subway with an emphasis on the influence of traveling convenience. In the first stage, we examine the Origin-Destination(OD) points of Beijing taxi trips and compare these locations with the respective nearest subway station. Statistics reveal several interesting conclusions. First, for approximately 24.89% of all trips, no convenient subway connections exist between the OD pairs. As such, a taxi becomes the only viable choice. Second, for 80.23% of the remaining 75.11%of trips(equivalent to 60.26% of all trips), access distance from either the origin or the destination to the nearest subway station is greater than 500 meters. This phenomenon indicates that walking distance plays an important role in travel mode choice. In the second stage, we examine groups of taxi trips with similar travel distances and travel times to reveal common features. We establish a preference rule in terms of travel distance and travel time.This determines whether an individual driver will take a taxi or the subway, using a pairwise comparison-based preference regression model. Tests indicate that more than 95% of taxi trips can be correctly predicted by this preference rule. This conclusion reveals that traveling convenience dominates the travel model choice between taxi and subway. All these findings shed light on the factors that influence travel mode choice behavior.     

A Novel Routing Method for Social Delay-Tolerant Networks

The lack of continuous connectivity and a complete path from source to destination makes node communication quite difficult in Delay-Tolerant Networks(DTNs). Most studies focus on routing problems in idealized network environments without considering social properties. Communication devices are carried by individuals in many DTNs; therefore, DTNs are unique social networks to some extent. To design efficient routing protocols for DTNs, it is important to analyze their social properties. In this paper, a more accurate and comprehensive metric for detecting the quality of the relationships between nodes is proposed, by considering the contact time, contact frequency, and contact regularity. An overlapping hierarchical community detection method is designed based on this new metric, and a tree structure is built. Furthermore, we exploit the overlapping community structure and the tree structure to provide message-forwarding paths from the source node to the destination node.The simulation results show that our Routing method based on Overlapping hierarchical Community Detection(ROCD) achieves better delivery rate than SimBet and Bubble Rap, the classic routing protocols, without affecting the average delay.     

干湿循环和吸力对非饱和下蜀土力学特性影响的试验研究

为研究干湿循环和吸力共同作用对非饱和下蜀土力学特性的影响,选取镇江某边坡的下蜀土为研究对象,通过非饱和直剪试验,对不同干湿循环次数及吸力水平下下蜀土力学特性的变化规律进行了研究.结果 表明:随着干湿循环次数的增加,下蜀土表面裂隙明显增加并具有不可逆性;下蜀土的抗剪强度经短暂增大后逐渐降低,并在第4次干湿循环作用后趋于稳定;下蜀土的黏聚力在经历短暂提高后逐渐降低并趋于稳定,而其内摩擦角则随干湿循环次数的增加变化幅度较小,呈上下波动态势;相同干湿循环次数下,吸力的存在对于下蜀土的黏聚力具有提升作用,而对土体内摩擦角的影响则不明显.研究结果可为干湿循环作用下下蜀土边坡的稳定性分析提供计算参数,具有实际工程意义.     

微生物燃料电池修复钒污染地下水的响应曲面优化研究

使用响应曲面法, 对单室微生物燃料电池去除五价钒的运行条件进行分析和优化。采用乙酸钠作为单室微生物燃料电池的碳源, 探讨钒初始浓度、COD初始浓度和电解液电导率对五价钒去除率的影响, 三因素三水平的响应曲面分析结果表明, 五价钒初始浓度对五价钒去除率的影响最显著, 其次为 COD 初始浓度, 最后是电解液电导率。利用响应曲面法得到最优实验条件: 五价钒初始浓度为75.44 mg/L, COD初始浓度为1007.48 mg/L, 电导率为11.98 mS/cm, 此时可获得五价钒的最大理论去除率80.31%。验证实验的结果证实了该优化方法的可靠性。研究成果可以促进微生物燃料电池技术在治理钒污染地下水领域的实际应用。     

Fe掺杂对BiTaO_4陶瓷样品介电和铁电特性的影响

为探究Fe掺杂对BiTaO4陶瓷样品介电特性和铁电特性的影响,采用传统固相烧结法制备了Bi Ta1-xFexO4-x(x=0,0.01,0.03)陶瓷样品,利用X线衍射仪和扫描电子显微镜对样品的晶体结构和表面形貌进行分析,利用精密阻抗分析仪和铁电分析仪对样品的介电性能和铁电性能进行检测.结果表明:Fe掺杂没有明显改变样品的晶体结构;随着Fe掺杂量的增加,样品的介电常数表现出较好的稳定性,介电损耗略有减小,且基本保持在tanδ=0.05以下,其漏电流先增大后减小,且掺杂样品均可得到比较完整的电滞回线.     

适用于可持续认证的生物质能温室气体排放核算方法

 能源领域可持续认证标准要有温室气体（greenhouse gas，GHG）排放核算方法作为支撑。中国尚未开发适用于生物质能可持续认证的GHG排放核算方法。本文梳理了GHG排放核算的一般方法，基于国外生物质能可持续政策要求与认证标准的相关方法学，识别出核算方法的关键要素。在对中国研究层面生物质能生命周期GHG排放核算不同认识进行梳理和讨论的基础上，提出了适合于中国可持续认证的核算方法的建议。     

关于清朝乾隆时期中英之间的一次科学交流——1792-1794年英国使团在中国的博物学活动及其幕后策划者

1792-1794年,马嘎尔尼率英国大使团访问中国,这是世界近代以来两大帝国之间发生的首次大规模外交活动。皇家学会主席班克斯希望借此增进对中国博物学的认识,实现对中国动、植物资源的科学与经济价值使用,以增强大英帝国实力,于是便主动帮助使团制定在中国的博物学活动规划。抵达中国后,以斯当东为首的博物学团体记载下大量博物情报,采集了许多植物标本,并多次与班克斯通讯,报告在中国的博物学见闻。英国使团的博物学活动体现出该时期中英科学文化交流与"西学东渐"十分不同的特点。