区块链技术与企业绩效:公司治理结构的调节作用

当前,我国正在全面迈进数字经济新时代.区块链技术作为数字经济最为重要的基础技术设施之一,正在加速推动新一轮产业变革和数字创新,被越来越多的企业接受和应用.区块链技术对企业绩效的作用机制是什么?针对以上问题,本研究通过倾向得分匹配方法(PSM)选取2014-2019年中国沪深A股上市公司为研究样本,以当年是否引入区块链技术作为公司治理手段为哑变量,通过计量分析研究了区块链技术应用与企业绩效之间的关系,并进一步探索了公司治理结构在区块链技术应用与企业绩效关系间的调节作用.研究发现,区块链技术应用对企业绩效有促进作用;当公司治理结构呈现较高独董比例和较高股权集中度时,区块链技术应用对企业绩效的促进作用得到加强.     

Noninformative priors for the between-group variance in the unbalanced one-way random effects model with heterogeneous error variances

For the unbalanced one-way random effects model with heterogeneous error variances, we propose the non-informative priors for the between-group variance and develop the first- and second-order matching priors. It turns out that the second-order matching priors do not exist and the reference prior and Jeffreys prior do not satisfy a first-order matching criterion. We also show that the first-order matching prior meets the frequentist target coverage probabilities much better than the Jeffreys prior and reference prior through simulation study, and the Bayesian credible intervals based on the matching prior and reference prior give shorter intervals than the existing confidence intervals by examples.     

区块链技术应用于政府采购信用体系建设中的价值与路径

随着政府采购的深入发展，政府采购信用体系逐渐出现政府采购信誉减损、信用信息开放和共享程度较低、信用信息的安全威胁增加、信用监管效果不佳以及失信惩戒政策执行遭遇阻塞等问题。区块链技术应用于政府采购信用体系建设中有利于提供安全的信息环境、有利于多主体参与、有助于多中心协同、能促进信用监管多元化。区块链技术在政府采购信用体系建设中的应用路径:以区块链思维重新架构政府采购信用体系的信用管理基础；以“去中心化”的信任机制完善信用信息公开与共享平台；以分布式账本结构打造多主体监管参与机制；以智能合约机制实现信用评估智能化。     

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.     

融资融券扩容和流动性

  流动性是市场的灵魂，金融创新的目的和结果是提高资产的流动性。2010年3月31日，证监会以促进市场流动性为目的，正式推出融资融券业务试点，并在2011年至2013年先后3次扩大中国A股市场融资融券标的股票的范围。因此，研究中国融资融券是否促进流动性并探究其内在机制具有非常重要的现实意义。         排除股指期货和股指期权等卖空机制的影响，运用面板回归方法和适合政策评估的双重差分法，分别检验2011年至2013年3次融资融券扩容对标的股票流动性的影响，并从融资和融券交易者的短期交易策略和标的股票股东结构变化两个方面探讨买空卖空机制与流动性因果关系的内在机制。         研究结果表明，融资和融券交易的双重引入降低了交易成本和价格影响，提高了标的股票的流动性。随着融资融券业务的深入开展和发展，融资融券标的股票扩容对价格影响方面的流动性的影响越来越强。融资交易者的短期动量交易策略降低了价格影响和交易成本，融券交易者的短期动量交易策略降低了价格影响，而对交易成本影响不显著。由于部分机构投资者退场，偏好短线投机炒作的中大型个体投资者入场，换手率高、流通市值低和特质波动率低等类型的标的股票组合的流动性提高更为明显。         融资融券交易提高标的股票流动性的研究结论补充了已有研究关于买空卖空机制对市场质量影响方面的实证证据，也为中国融资融券业务的发展和完善提供借鉴意义。     

凝固型大米风味酸奶的研制

用大米蛋白或大米蛋白水解物部分替代牛乳粉生产大米风味酸奶,以谷糠乳杆菌和乳酸乳球菌乳酸亚种为发酵菌种,以酸度和感官为评价指标,通过大米蛋白及其水解物添加量、大米蛋白水解度、乳糖补加及蔗糖添加研究对大米风味酸奶酸度和感官的影响。结果表明,大米风味酸奶的酸度和感官评分随大米蛋白添加量的增加而降低。产品酸度随大米蛋白水解度增加而增大,大米蛋白水解度为7.5%时感官得分最高;产品酸度和感官评分随大米水解物添加量增加而降低,大米蛋白水解物添加量在40%以下时,均可生产出合格的大米风味酸奶。补加乳糖对产品酸度和感官无显著影响。添加蔗糖对产品酸度无显著影响,但对产品感官影响显著,蔗糖添加量在4~6%时,大米风味酸奶的感官得分最高,表现为色泽均匀,质地较细腻,未见乳清析出,凝乳稳定,口感较细腻柔滑,酸甜度适中,米香风味浓郁。     

战略科技人才培育路径仿真研究

采用文献综述和探索性因子分析相结合的方法,确定战略科技人才具有学识广、工作专注、品行优、使命感、战略思维5个主要特质。然后基于我国科技人才政策体系,通过问卷调查收集了116份样本数据,采用偏最小二乘法的结构方程建模(PLS-SEM),进行路径仿真,探讨了我国科技人才政策体系对战略科技人才特质的影响机理,共确定了22条培育战略科技人才的路径,在反映出我国科技人才政策体系严峻形势的同时,又为科技人才政策的改进和完善提供了一定理论指导。     

Life Satisfaction of Rural Migrant Workers in Urban China: The Roles of Community Service Participation and Identity Integration

Abstract

China is home to approximately 245 million rural-to-urban migrant workers. The influx of migrants into urban areas has posed various challenges for local social service systems. Recently, increasing number of community services have been developed to meet the growing service demands from the migrant population. However, whether increase in community service use results in improved wellbeing among migrant workers remains critically unexplored. As such, this study examines the role of community service use in migrant workers’ life satisfaction and the potential mediating effect of identity integration in Shenzhen, China. Bootstrapped models were adopted to examine relationship among variables. Drawing from a sample of 1,087 rural-to-urban migrant workers, we found that community service use is positively correlated with both identity integration and migrant workers’ life satisfaction. Moreover, identity integration served as a partial mediator between community service use and life satisfaction. The mediating effect of identity integration was found to increase with age. This study highlights that diverse services should be implemented to address divergent needs of migrants in different age groups. Community service can also serve as a vehicle to foster integration among migrant workers in host communities, especially for older age groups. Future studies may further investigate the relationships between community social capital, community social support, quality of community-based organization and frequency of service use so as to optimize the life satisfaction of migrant workers.     

Estimation of system reliability for exponential distributions based on L ranked set sampling

Abstract

In the case where strength and stress both follow exponential distributions, this paper considers the maximum likelihood estimator (MLE) of the system reliability based on L ranked set sampling (LRSS). The proposed MLE is shown to have existence, uniqueness and asymptotic normality, and its asymptotic variance is obtained by the Fisher information matrix of LRSS. The values of asymptotic relative efficiencies show that the proposed MLE is always more efficient than the MLE using simple random sampling (SRS). However, the MLE using LRSS cannot be written in closed form. Therefore, the modified MLE is proposed using the technique replaced some terms in the maximum likelihood equations by their expectations. The newly modified MLE using LRSS is shown to be superior to the MLE using SRS. Finally, the proposed method is applied to a real data set on metastatic renal carcinoma study.     

逻辑机器哲学的新发展

逻辑机器哲学是由美国当代哲学家、计算机科学家勃克斯提出的一种哲学思想,它是在信息时代计算机和网络技术迅猛发展的背景下提出的哲学新思维,又是对哲学史上的朴素唯物论、机械唯物论的继承与发展。在逻辑机器哲学中,拉美特利"人是机器"这个受尽奚落的命题成了其哲学思想的基本假定。它使得"人是机器"的哲学意蕴在计算机科学和信息技术蓬勃发展的今天可以得到新的阐释。尽管面临着许多挑战,但它为计算机科学哲学和信息技术哲学的诞生铺平了道路。近年来认知科学哲学的发展,把逻辑机器哲学研究推向了一个新的阶段,其标志是人工生命哲学的诞生。逻辑机器哲学研究为复杂系统科学视野下的人工生命及其哲学的新发展奠定了坚实的基础。