理性人的人情味：快手“老铁经济”的内在机制和逻辑

以中国用户规模最大短视频平台之一快手头部主播直播带货推广项目的案例和数据分析为基础,构建解释快手直播电商经济底层逻辑的社会学机制模型.提出快手直播电商经济背后的3种社会学机制:关键影响者逻辑、身份认同逻辑和社会网络逻辑.通过LDA文档主题生成模型将快手主播的直播语义字段进行文档主题生成归类,发现情感因素和理性因素词交互影响受众的购买决策,它背后的社会学作用机制是关键影响者逻辑和身份认同逻辑.2020年快手直播电商半年交易额已达1044亿元,理解快手直播背后的影响机制,能够持续优化推广模型,在互联网流量广告领域具有重要的应用价值.     

国有风险资本与企业融资约束: 如愿以偿还是事与愿违?

我国国有风险资本是否实现了设立之初的目标,即是否纾解了企业融资困难呢?文章基于上市企业微观数据和手动采集的国有风险资本数据对此进行了系统研究.实证结果稳健地显示,国有风险资本可有效缓解企业后续融资约束,我国政府参与风险投资活动是有效的.进一步地,高持股比例、多联合投资、高政治层级的国有风险资本对受资助企业融资约束的缓解作用更强;且国有风险资本对经济欠发达、低制度质量环境下的企业、面临高环境不确定性和高竞争程度企业、民营企业、成长期与动荡期企业能产生更大的影响.机制检验表明,国有风险资本既能通过认证作用显著降低企业信息不对称程度,又能发挥政治关联的资源效应,包括显著促进银企关系和企业的商业信贷获取能力,并提升企业获得政府补贴的水平,从而减轻企业资金负担,缓解其融资约束.经济后果分析表明,国有风险资本能显著降低企业外部融资的股权资金成本和债务资金成本,帮助改善企业融资贵的难题,而且国有风险资本有助于企业在创新和经营方面的良性发展.但国有风险资本并未起到有效监督作用,不能缓解企业代理问题,尤其是会导致第一类代理成本的明显提高,而高管薪酬提升是其中的重要原因.据此,文章认为在未来的国有风险资本发展中,要把握"政府角色"介入的尺度,完善国有风险资本对企业的监督管理机制.同时适当兼顾各地区发展不平衡的情况,对中西部地区的国有风险资本发展提供适当且必要的帮助,以促进国有风险资本在新时期的长足发展.     

利用价值工程在棚户区项目拆迁地块选址决策的模型建立

本文以价值工程理论为基础,收集现有不同地块基础数据,利用多元线性回归方法确定备选方案棚户区改造项目的成本系数.通过分析影响拆迁地块选址决策影响因素,利用层次分析法确定各备选方案功能系数.对各备选方案的价值系数进行计算后,以价值系数为评价值确定最优拆迁地块.     

Who benefits from partial tax coordination?

In this paper, we investigate whether partial tax coordination is beneficial to countries within and outside a tax union, in which countries are supposed to compete in taxes and infrastructure. Our results demonstrate that a subgroup of countries agreeing on a common tax rate can harm both member and nonmember states. This is in contrast to the classical findings that partial tax harmonisation is Pareto improving. When a minimum tax rate is imposed within a tax union, we demonstrate that it does not necessarily improve the welfare of the member countries. Moreover, both the high‐tax and low‐tax countries can be worse off. This conclusion is at odds with the classical result that a high‐tax country benefits from the imposition of a lower tax bound.     

金融科技对传统银行行为的影响——基于互联网理财的视角

本文使用2011-2015年263家银行的年报数据和北京大学数字金融研究中心基于蚂蚁金服用户数据构建的地市级数字金融普惠指数,探究金融科技的发展对银行行为的影响。研究发现金融科技的发展实质上推动了一种变相的利率市场化,改变了银行的负债端结构,使得银行负债端越来越依赖于同业拆借等批发性资金。负债端结构的改变导致银行资产端风险承担偏好上升,但是借贷利率和净息差都有所下降。即银行选择了更高风险的资产来弥补负债端成本上升所造成的损失,但并没有将成本向下游企业转移。此外,本文还发现规模越大的银行受到金融科技的冲击越小。     

China’s Contingencies: Critical Geopolitics,Chinese Exceptionalism and the Uses of History

This paper examines the intimate relationship between narratives emanating from China and their uses of Chinese history, and how such perspectives inform China’s geopolitical positioning and practices in lieu of its purported ‘rise’. Taking inspiration from the deconstructive impetus of critical geopolitics, this article contends that these historical claims to China’s rise constitute deterministic accounts, hinging on the notion of Chinese exceptionalism to provide discursive backing for a Sinocentric geopolitical order in the coming decades. This in turn downplays ‘alternative’ historiographies that can shed light on how the nature of China’s emergence may be more dependent on and shaped by the external environment than previously acknowledged. Building on the historical-geographical expositions related to the idea of contingency, this article demonstrates how China (whether it be in the past or present) cannot be seen as operating in a vacuum but has to constantly negotiate and adjust its strategy of engagements/interactions based on the specific demands imposed by world politics. Specifically, by elucidating these dimensions through cross-strait relations between China and Taiwan, it is argued that understanding China’s contingencies can raise important questions for us to critically appreciate the contextual actors, processes and relationships that differentially impact on China’s engagements in the world.     

Board directors with foreign experience and stock price crash risk: Evidence from China

This study examines the impact of board directors with foreign experience (BDFEs) on stock price crash risk. We find that BDFEs help reduce crash risk. This association is robust to a series of robustness checks, including a firm fixed effects model, controlling for possibly omitted variables, and instrumental variable estimations. Moreover, we find that the negative association between BDFEs and crash risk is more pronounced for firms with more agency problems, weaker corporate governance, and less overall transparency. Our findings suggest that the characteristics of board directors matter in determining stock price crash risk.     

LT码新型度分布及其在电力线通信中的应用

Luby变换(Luby Transform,LT)码作为信道编码应用于电力线通信(Power Line Communication,PLC)，可实现电信号的可靠传输。度分布对LT码编译码性能的影响至关重要。为了得到更优的度分布，首先调整二进制指数分布(Binary Exponential Distribution,BED)中的度数比例，获得一种译码性能更优的改进的二进制指数分布(Improved BED,IBED)。然后，根据IBED在冗余度较小时译码成功率高，而冗余度增大后鲁棒孤子分布(Robust Soliton Distribution,RSD)的译码性能表现更佳的特点，通过求和归一化的方式将IBED与RSD两种度分布的优势进行有机结合，提出一种新型二进制鲁棒孤子分布(Binary RSD,BRSD)。仿真结果表明，与其他方法及传统的RSD相比，采用新度分布进行LT编码，可明显降低译码开销，并节约编译码耗时。将新型度分布应用于基于LT码的PLC系统中，能有效地抑制PLC信道中各种噪声对电信号的干扰，并提高通信效率。     

基于AD9361的掌上型LTE RRU设计与开发

当前小体积远端射频单元（Remote Radio Unit,RRU）主要是皮站级别的Pico-RRU，其重量和体积仍然难以满足掌上型的要求。为此，采用高集成度的AD9361芯片来实现长期演进（Long Term Evolution，LTE）宽带收发信机功能，配合时钟同步模块、放大器模块和控制接口电路等一起构建低成本的掌上型RRU。主要解决了基于AD9516的时钟同步、低相位噪声设计和高灵敏度接收机设计三个技术难点，成功实现了掌上型、高性能、低成本的设计目标。整个RRU样机尺寸为18 cm×10 cm×2 cm，质量约500 g，量产成本千元以内。测试表明，该RRU下行误差向量幅度（Error Vector Magnitude，EVM）小于3%，优于3GPP要求的8%；10 MHz带宽时上行接收机灵敏度优于3GPP要求的-93.5 dBm。     

天地一体化信息网络中天基卫星网络架构设计

为了充分利用各种空间设施资源，提升天基信息网络覆盖与传输能力，分别从天基信息网络体系架构和逻辑功能架构角度进行了系统性设计。与以往天基网络的设计不同，该设计更注重各类卫星网络的深度融合应用，为此将网络虚拟化技术引入天基卫星网络。同时，还提出了解决新架构下卫星组网难题的方法，将电磁涡旋、卫星灵活载荷和边缘计算技术设计到天基网络。仿真表明，所提出的架构能有效提升频谱利用率和减少卫星网络信令开销。