推进物质流和社会经济代谢研究,助力实现联合国可持续发展目标

实现联合国可持续发展目标的进度评估和路径选择,依赖于相关指标的定量评价及对社会经济和自然环境系统耦合关系的刻画。物质流和社会经济代谢分析方法基于质量守恒和生命周期思想,可以深刻地描述物质存量动态变化及其与流量的关系,分析资源和产品贸易及其对区域物质循环的影响,理解不同资源在生产与消费过程中的耦合与冲突关系。社会经济系统中物质代谢的分析和调控,是实现可持续发展的重要前提,也有助于绿色经济、循环经济、低碳经济等可持续发展战略的顺利实施。文章介绍了物质流和社会经济代谢分析方法的基本框架,并通过具体案例展示其如何用于分析全球、国家和产业可持续发展中的中长期资源、能源和气候挑战及相应的对策,从而助力实现联合国2030年可持续发展目标。在此基础上,提出了推进中国物质流和社会经济代谢研究的若干建议。     

期刊CiteScore评价研究

【目的】 比较CiteScore与影响因子(IF)在学术期刊评价中的异同。【方法】 以2012—2016年Scopus与Web of Science数据库同时收录的期刊为数据来源,通过R语言测评样本期刊CiteScore指数与IF数据库中2年影响因子(IF2)、5年影响因子(IF5)的相关性。【结果】 2012—2016年期刊的Citescore值均与IF2及IF5呈线性相关。CiteScore统计范围涵盖所有文章类型,因此许多综合类期刊的CiteScore值低于IF值,但对于只发表研究论文和综述论文的期刊,CiteScore值高于IF值。【结论】 CiteScore覆盖面更广,并且兼顾IF2和IF5两个数值的特点,期刊IF计算方式与期刊收录学科仍存在问题。     

Intermittent control strategy for synchronization of fractional-order neural networks via piecewise Lyapunov function method

In this paper, the synchronization problem of fractional-order neural networks (FNNs) with chaotic dynamics is investigated via the intermittent control strategy. Two types of intermittent control methods, the aperiodic one and the periodic one, are applied to achieve the synchronization of the considered systems. Based on the dynamic characteristics of the intermittent control systems, the piecewise Lyapunov function method is employed to derive the synchronization criteria with less conservatism. The results under the aperiodically intermittent control show more generality than the ones via the periodically intermittent control. For each of the aperiodic and periodic cases, a simple controller design process is presented to show how to design the corresponding intermittent controller. Finally, two numerical examples are provided to demonstrate the effectiveness of the obtained theoretical results.     

Understanding the topic evolution of scientific literatures like an evolving city: Using Google Word2Vec model and spatial autocorrelation analysis

Topic evolution has been described by many approaches from a macro level to a detail level, by extracting topic dynamics from text in literature and other media types. However, why the evolution happens is less studied. In this paper, we focus on whether and how the keyword semantics can invoke or affect the topic evolution. We assume that the semantic relatedness among the keywords can affect topic popularity during literature surveying and citing process, thus invoking evolution. However, the assumption is needed to be confirmed in an approach that fully considers the semantic interactions among topics. Traditional topic evolution analyses in scientometric domains cannot provide such support because of using limited semantic meanings. To address this problem, we apply the Google Word2Vec, a deep learning language model, to enhance the keywords with more complete semantic information. We further develop the semantic space as an urban geographic space. We analyze the topic evolution geographically using the measures of spatial autocorrelation, as if keywords are the changing lands in an evolving city. The keyword citations (keyword citation counts one when the paper containing this keyword obtains a citation) are used as an indicator of keyword popularity. Using the bibliographical datasets of the geographical natural hazard field, experimental results demonstrate that in some local areas, the popularity of keywords is affecting that of the surrounding keywords. However, there are no significant impacts on the evolution of all keywords. The spatial autocorrelation analysis identifies the interaction patterns (including High-High leading, High-Low suppressing) among the keywords in local areas. This approach can be regarded as an analyzing framework borrowed from geospatial modeling. Moreover, the prediction results in local areas are demonstrated to be more accurate if considering the spatial autocorrelations.     

外部知识源化、知识积累与中国工业绿色增长——动态异质门槛效应研究

针对开放式创新驱动与绿色发展融合下工业绿色增长路径及动力来源多元化特征，基于中国工业2009-2015省际面板数据，通过考虑非期望产出的Super-SBM模型测算环境和能源约束下的工业绿色增长结构，并采用改进的动态门槛回归模型，从地区知识积累视角系统探究外部知识源化路径驱动工业绿色增长机制的知识积累动态门槛效应及其时空异质性。研究表明：中国工业绿色增长整体水平较低，地区异质性显著；总体上，外部知识源化对工业绿色增长起到了正向作用，但其存在显著的知识积累异质门槛特征：知识积累一旦突破了临界规模，外部知识源化路径驱动工业绿色增长的正向效应则呈现减弱，且知识积累门槛时空分布存在较大差异。     

新工科背景下机器人工程专业教学模式探索

随着我国智能制造业的快速发展,机器人产业也快速增长,社会急需大量的机器人工程专业人才,机器人学科作为一门新工科,其相关专业的人才培养模式还在不断摸索中。传统的教学模式已不能满足新工科的内涵和发展要求。因此,本文以产业需求为导向,分析了当前机器人工程专业在人才培养过程中存在的问题,并结合自身的实践项目和教学经验,为高校机器人工程专业人才培养提出建议。     

基于科学文献计量的国内区域创新生态系统的研究进展及趋势分析

采用文献计量分析方法,利用CiteSpace Ⅴ对2000-2020年间中国知网、万方数据和重庆维普期刊数据库收录的CSSCI、北大核心期刊和中国科学引文数据库(CSCD)中发表的关于区域创新生态系统的相关文献进行分析,探索区域创新生态系统研究现状及发展趋势.研究结果表明,国内区域创新生态系统的研究呈现出区域性特征,且各研究机构之间的合作较少;国内区域创新生态系统的研究热点主要聚焦于生态系统的共生演化和生态位等方面;结合区域特点、生态学特征以及利用多源异构数据进行研究是未来区域创新生态系统研究的重要趋势和方向.     

音视频传输系统中的网络融合

基于音视频系统对IT技术的需求,分析在进行AV传输系统设计中,重点考虑网络拓扑结构、服务质量管理、PTP时钟三个问题。     

Surface superconductivity in the type II Weyl semimetal TaIrTe4

The search for unconventional superconductivity in Weyl semimetal materials is currently an exciting pursuit, since such superconducting phases could potentially be topologically non-trivial and host exotic Majorana modes. The layered material TaIrTe₄ is a newly predicted time-reversal invariant type II Weyl semimetal with the minimum number of Weyl points. Here, we report the discovery of surface superconductivity in Weyl semimetal TaIrTe₄. Our scanning tunneling microscopy/spectroscopy (STM/STS) visualizes Fermi arc surface states of TaIrTe₄ that are consistent with the previous angle-resolved photoemission spectroscopy results. By a systematic study based on STS at ultralow temperature, we observe uniform superconducting gaps on the sample surface. The superconductivity is further confirmed by electrical transport measurements at ultralow temperature, with an onset transition temperature (T_c) up to 1.54 K being observed. The normalized upper critical field h*(T/T_c) behavior and the stability of the superconductivity against the ferromagnet indicate that the discovered superconductivity is unconventional with the p-wave pairing. The systematic STS, and thickness- and angular-dependent transport measurements reveal that the detected superconductivity is quasi-1D and occurs in the surface states. The discovery of the surface superconductivity in TaIrTe₄ provides a new novel platform to explore topological superconductivity and Majorana modes.     

Convergent genomic signatures of high-altitude adaptation among domestic mammals

Abundant and diverse domestic mammals living on the Tibetan Plateau provide useful materials for investigating adaptive evolution and genetic convergence. Here, we used 327 genomes from horses, sheep, goats, cattle, pigs and dogs living at both high and low altitudes, including 73 genomes generated for this study, to disentangle the genetic mechanisms underlying local adaptation of domestic mammals. Although molecular convergence is comparatively rare at the DNA sequence level, we found convergent signature of positive selection at the gene level, particularly the EPAS1 gene in these Tibetan domestic mammals. We also reported a potential function in response to hypoxia for the gene C10orf67, which underwent positive selection in three of the domestic mammals. Our data provide an insight into adaptive evolution of high-altitude domestic mammals, and should facilitate the search for additional novel genes involved in the hypoxia response pathway.