外语能力与科学研究的密切联系——周立伟院士访谈

近日对我国著名电子光学和光电子成像专家周立伟院士进行了访谈。访谈中，周院士首先分享了自己学习英语和俄语的经历，强调了自主学习能力的重要性；其次，周院士详细论述了外语教学，尤其是英语教学的必要性，指出英语能力与科学研究紧密相关，英语教学不可或缺；之后周院士分析了研究生在英语学习和科学研究方面存在的问题，并讨论了大学中开设人文课程的迫切性；最后，周院士对上理工师生提出了建议与期望。     

浙江省城市绿色技术创新效率评价及影响因素分析

基于网络DEA模型和Malmquist指数模型，利用浙江省11个地级市的2011-2020年的数据，以降维后的污染指数为非期望产出对绿色技术创新效率进行测度和分析。发现:浙江各市总体上成果转化阶段的效率优于研发阶段，城市间发展差异较大；整体TFP指数均值为1.121，其提升主要源自技术进步；城镇化水平、产业结构优化、对外开放、政府干预和研发强度对绿色技术创新效率有促进作用，但经济发展水平与绿色技术创新效率的U型关系不显著。     

An Optimization‐Based Framework for the Identification of Vulnerabilities in Electric Power Grids Exposed to Natural Hazards

This article proposes a novel mathematical optimization framework for the identification of the vulnerabilities of electric power infrastructure systems (which is a paramount example of critical infrastructure) due to natural hazards. In this framework, the potential impacts of a specific natural hazard on an infrastructure are first evaluated in terms of failure and recovery probabilities of system components. Then, these are fed into a bi‐level attacker–defender interdiction model to determine the critical components whose failures lead to the largest system functionality loss. The proposed framework bridges the gap between the difficulties of accurately predicting the hazard information in classical probability‐based analyses and the over conservatism of the pure attacker–defender interdiction models. Mathematically, the proposed model configures a bi‐level max‐min mixed integer linear programming (MILP) that is challenging to solve. For its solution, the problem is casted into an equivalent one‐level MILP that can be solved by efficient global solvers. The approach is applied to a case study concerning the vulnerability identification of the georeferenced RTS24 test system under simulated wind storms. The numerical results demonstrate the effectiveness of the proposed framework for identifying critical locations under multiple hazard events and, thus, for providing a useful tool to help decisionmakers in making more‐informed prehazard preparation decisions.     

Language roulette – the effect of random placement on refugees’ labour market integration

Placement of refugees and subsequent labour market integration within a host country represents a key challenge for policymakers and has emerged as one of the most divisive topics in the public debate. Immigration policy in Switzerland adopts random placement of asylum seekers across its different language regions. Hence, this policy allows to estimate the causal effect of language skills on employment chances, as refugees are exogenously placed across regions where the spoken language could either match or deviate from individual language skills. The results of this ‘natural experiment’ indicate substantially higher probabilities of finding employment when asylum seekers are placed in regions with a lingua franca that matches their individual language skills. Additionally, the findings suggest that language course participation can offset the reduced likelihood of employment in cases of a language mismatch. While random placement of refugees may be desirable for political reasons, it is detrimental to the economic integration process. Thereby, the study draws relevant conclusions for a larger European immigration policy.     

考虑重复购买因素的品牌竞争对新产品扩散的影响研究——基于小世界网络的仿真环境

在对品牌竞争影响要素分析的基础上，考虑重复购买在新产品扩散过程中的调节效应，构建以消费者微观采纳机制为核心的新产品扩散的阈值模型，在小世界网络仿真情境下，运用多智能仿真方法对品牌竞争与新产品扩散之间的影响关系进行分析，研究结果表明：转换成本对新产品扩散的速度和深度的影响存在一定的"条件区域"，在该区域之外两者不存在显著的影响关系；进入时间与两种竞争性品牌的扩散速度存在一致的负向的影响关系，而对两种竞争性品牌的扩散深度的影响方向则相反；在此过程中，重复购买系数起着一定的调节效应，会在一定程度上放大或缩小转换成本及进入时间对新产品扩散的影响效应。通过本文的研究，不仅可以进一步丰富和完善竞争性产品创新扩散的相关理论，也可以为企业的新产品推广实践提供决策支持。     

基于Petri网的微博网络信息传播模型

微博网络中的信息传播模型是分析用户行为，找出传播路径，确定领袖人物，发现舆情热点等研究的基础。虽然多种不同角度的信息传播模型已经得到广泛研究，但缺乏对信息动态传播过程的直观描述。本文基于Petri网的结构和特征，针对微博网络信息传播过程，提出了一种简单直观的描述模型，该模型首先对微博网络的信息动态传播过程中的对象进行结构化描述。本文根据微博网络的用户结构关系，并利用Petri网的相关理论，形式化解释和定义信息传播基本对象，从而更加直接描述了微博网络中的转发、评论、回复等多种用户行为。在此基础上，本文利用Petri网能够描述信息流动问题的特征，结合颜色Petri网和时延Petri网，从Petri网系统的角度表示信息动态传播路径，并研究网络的动态性质和传播条件，使得信息传播模型更加真实地模拟信息传播情况。最后本文分析信息传播算例和新浪微博真实数据实验，验证了模型的有效性和可行性，为舆情态势分析以及用户行为的研究提供帮助和支持，同时也为其它社交网络信息传播的用户行为描述提供了新的思路。     

网络思想政治教育研究的“空间范式”

思想政治教育学科在理论研究中已经形成了多种范式。从现实社会空间向虚拟网络空间的“空间转向”，为思想政治教育新范式的形成提供了崭新的空间条件。网络思想政治教育的快速发展也为其“空间范式”的提出进行了必要的知识积累。“空间范式”凸显马克思主义公共性理论和社会空间理论的理论特性，旨在透过“空间”的维度，发展网络思想政治教育的理论和方法体系。“空间范式”的提出对于进一步凸显网络思想政治教育研究的学术旨趣，凝聚学科共识，培育知识信念，整合学术资源，建构更加专业的话语体系，形成一个影响广泛的网络思想政治教育学术共同体具有重要意义。     

Perceived group cohesion versus actual social structure: A study using social network analysis of egocentric Facebook networks

Research on group cohesion often relies on individual perceptions, which may not reflect the actual social structure of groups. This study draws on social network theory to examine the relationship between observable structural group characteristics and individual perceptions of group cohesion. Leveraging Facebook data, we extracted and partitioned the social networks of 109 participants into groups using a modularity algorithm. We then surveyed perceptions of cohesion, and computed group density and size using social network analysis. Out of six linear mixed effects models specified, a random intercept and fixed slope model with group size as a predictor of perceived group cohesion emerged as best fitting. Whereas group density was not linked to perceived cohesion, size had a small negative effect on perceived cohesion, suggesting that people perceive smaller groups as more cohesive. We discuss the potential of social network analysis, visualization tools, and Facebook data for advancing research on groups.     

历史城区自行车绿道系统规划与设计的实证研究

为提升历史城区的绿道品质，优化非机动车出行环境，对自行车绿道系统的规划与设计方法进行了实证研究。根据自行车绿道系统的特性，按照空间形态特性将历史城区的自行车绿道系统分为单元、廊道及节点等3类要素，通过自组织映射图模型、最短路算法、旅行推销员算法及自行车路阻函数等，在地理信息系统上建立了基于赋权系数的自行车绿道系统规划方法，并应用所提出的方法对西安市主城区自行车绿道系统进行实证研究。研究结果表明，西安可以构建成包括22条骑行廊道、总长度142.6 km的自行车绿道网络，证明提出的方法能建立适用于历史城区出行特性的自行车绿道系统。     

The coevolution of trade agreements and investment treaties: Some evidence from network analysis

Regional trade agreements (RTAs) and bilateral investment treaties (BITs) are expected to promote trade and investment relationships. One critical feature of such agreements is the network, so the multiplex coevolution of RTAs and BITs should be captured by the dynamics of their two networks. Although many studies have examined the roles of RTAs and BITs, most studies do not account for crucial network properties. This study explores how RTAs and BITs coevolve by applying a stochastic actor-oriented model of multiplex network evolution. In particular, we examine the roles of (i) cross-network dyadic interinfluences and (ii) within- and cross-network preferential attachments to discuss the dynamic relationships between RTAs and BITs. The results are as follows. First, our estimation supports cross-network dyadic interinfluences. Countries that sign a BIT are willing to establish an RTA, while those that sign an RTA are reluctant to establish a BIT. Second, concerning preferential attachments, countries prefer to sign BITs with partners that have more RTA and BIT links. However, countries tend to form RTAs with partners that have more BIT links but are reluctant to form RTAs with those that have more RTA links. We discuss possible justifications for these results, including arguments regarding the benefits and costs associated with the formation of RTAs and BITs.