粤港澳大湾区制造业集聚与区域创新

以2009—2020年粤港澳大湾区11个城市为研究对象，探讨制造业集聚与区域创新的关系。研究发现，制造业集聚显著提高区域创新水平，可通过提高企业竞争这一路径实现。进一步分析发现，金融业集聚对区域创新发展具有显著的正向关系，金融产业和制造业产融协同集聚显著提高区域创新水平。研究结果表明，制造业集聚加剧产业内部企业创新竞争，带动区域创新发展，且金融业在创新中起到积极的推动作用。指出应鼓励区域企业创新竞争，优化营商环境，为产业融合发展提供保障。     

Effects of cohort size on college premium: Evidence from China's higher education expansion

In this paper, we document the lesser-known heterogeneous trends of college/non-college earnings premium across age groups from 1995 to 2013 in China. Specifically, the college premium in 2013 for the younger group (age 25–34) was about 30 percentage points, similar to the level in 1995, while the college premium in 2013 for the older group (age 45–54) increased to 50 percentage points, nearly double that of 1995. To attribute these divergent trends of the college premium to the changes in the relative size of college workers, we use the model by Card and Lemieux (2001), which incorporates imperfect substitution between similarly educated workers in different age cohorts. Due to the distinctions of these trends in China, our identification is free of the overestimation issue that the existing studies suffer. Our results are similar to those in the U.S., U.K., Canada, and Japan. Holding the age cohort and survey year constant, a one unit increase in log relative size of college workers is associated with about 10 percentage points decrease in college/non-college premium and about 18 percentage points decrease in college/high school premium. We further find that the negative effect is much more substantial among the new entrants (age 25–29) than experienced workers (age 30–54). By this pattern, we demonstrate that the new labor market entrants are more sensitive to their own cohort size and argue that the confounding ability composition effect should not be a serious issue.     

深度学习方法在作物遥感分类中的应用和挑战

[目的]准确估算作物的面积和分布对粮食安全至关重要。与传统的机器学习方法相比,深度学习具有多种优势,如端到端训练、可迁移性。为有效利用高时空数据进行作物识别提供了新的机遇。已有多种模型被应用于作物分类任务中,针对不同的分类任务,如何有效地选择模型,并对其进行训练和使用已成为关键问题。[方法]文章回顾了利用深度学习模型对作物分类的主要研究。N维卷积神经网络(N-D CNN)(N=1、2、3)和递归神经网络(RNN)已被有效用于作物分类任务。长短期记忆RNN(LSTM RNN)和门控循环单元RNN(GRU RNN)是RNN的变体,解决了随着时间序列增加RNN出现的梯度消失或爆炸问题。此外,还有研究使用CNN和RNN(我们称为RCNN)的混合模型对作物进行分类。该文首先阐述了使用深度学习方法进行作物制图的背景和意义,并介绍了CNN和RNN模型结构。然后回顾了一些典型的研究,包括模型的结构、遥感数据源、数据处理方法和分类精度。最后,总结了使用深度学习方法进行作物分类的挑战以及现有解决方案的局限性。[结果](1)1-D CNN可用于提取时间特征,或时间+光谱特征,分类效果良好;2-D CNN已被广泛应用于单时相数据的空间特征提取,分类精度依赖于数据源;3-D CNN应用较少,但具有很大的潜力,尤其是时间+空间维度的特征提取;(2)相同条件下(架构、数据源、研究区域、类别),LSTM RNN和GRU RNN分类效果通常高于普通RNN,而前两者的效果差距不大,但GRU RNN训练时间较短;(3)CNN+RNN混合模型(RCNN)用RNN比3-D CNN更适合提取时间特征。这主要是由于RNN建立了对序列数据的长期依赖,而3-D CNN卷积核是局部计算的。[结论]通过分析,认为深度学习技术是作物遥感分类的有效工具。此外,与其他模型相比,RCNN,3-D CNN和GUR RNN具有更大的潜力。     

航班计划优化研究概述

从航班计划优化的不同时间阶段分析,可以将航班计划优化分为航班计划静态编排优化、基于航班延误预测的航班计划动态反馈优化和基于机场协同决策(A-CDM)的航班计划动态调整角度三类;进而从航班时刻、机型指派、航班频率等编制环节分析了航班计划静态编排优化;随后利用延误波及预测与数据挖掘预测的优化方法分析了基于航班延误预测的航班计划动态反馈优化的相关研究。最后,根据航班计划优化复杂性分析,给出了航班计划优化的发展趋势和未来研究方向。     

渠道合作情境下合同双元功能对主动和被动投机行为的影响差异研究

基于交易成本理论，在渠道合作情境下，以制造商的合同监督和企业间联合行动为工具测量合同治理的保障功能和协作功能，探讨二者对经销商主动投机行为和被动投机行为的影响差异。通过对512份问卷数据的统计分析，得到以下结论：第一，合同监督有助于抑制经销商的主动投机行为，但对其被动投机行为的影响不显著；第二，企业间联合行动有助于抑制经销商的被动投机行为，但对其主动投机行为的影响不显著；第三，经销商的主动投机行为和被动投机行为均会负向影响合作绩效；第四，经销商的主动投机行为中介合同监督对合作绩效的正向影响，被动投机行为中介企业间联合行动对合作绩效的正向影响。     

在热电联产企业中精益成本管理的评价指标及应用对策

论文从热电联产企业的特征入手,通过对精益成本管理理论的研究,总结出热电联产企业精益成本管理的评价指标,并通过对指标的分析总结出精益成本管理在热电联产企业实际应用中的管理对策。     

德国零售巨头阿尔迪经营战略分析

随着经济全球化的发展,科学技术日新月异,人们的消费结构和消费习惯也在不断地改变,传统的零售业面临着巨大的挑战,但德国阿尔迪依旧在当下保持着零售巨头的称号。论文对德国零售巨头阿尔迪的经营战略进行分析,并结合阿尔迪的经营策略为中国零售业提出建议和启示。     

女性高管对企业研发创新的影响：一个有调节的中介模型

企业创新是企业持续发展的内在动力,也是推动国家产业升级、建设创新型国家的重要举措.近年来女性高管比重不断提高,学术界开始关注女性高管对企业研发创新的影响.以沪深两市2010—2018年A股上市公司为研究样本,实证检验女性高管对企业研发创新投入的影响.结果表明:女性高管负向影响企业研发创新投入;其负向作用以风险承担为中介实现;企业所有制调节了中介过程的后半段路径.     

Shariah compliance and corporate cash holdings

This study investigates the influence of Shariah compliance status on cash holding levels and the speed of adjustment of non-financial listed firms in six Gulf Cooperation countries from 2005 to 2016. The results show that Shariah compliance status has a significant effect on firms’ cash holding decisions. Shariah-compliant firms have significantly higher cash holding levels than non-Shariah-compliant firms. Further, Shariah-compliant firms adjust more quickly towards their target cash holdings than their conventional counterparts. In our view, Shariah-compliant firms are subject to multiple restrictions that limit their external financing channels. Therefore, holding larger cash reserves is important as it helps gain from the transaction cost motive of holding cash. The findings of this study have important implications for regulators, investors and managers. To the best of our knowledge, this study is the first to compare the effect of Shariah compliance on firms’ cash holdings and the speed of adjustment towards the trade-off theory’s optimal cash holding target.     

Adoption des Politiques de Protection de l'Environnement et performance des Entreprises Camerounaises

The objective of this paper is to evaluate the effect of the environmental protection policies of by Cameroonian firms on their performance. It uses the endogenous switching regression technique and propensity scores applied to micro-data from 639 firms in Cameroon. The results show that only 17% of firms adopt these measures, while on average 85% of firms produce solid, gaseous or liquid waste. The results also indicate that the adoption of these environmental protection policies increases operating costs while significantly improving the turnover and the performance of the productive capacity of the company. These increases are 39.11%, 58.6%, and 38.63% for operating costs, turnover and return on productive capacity of the company, respectively. However, firms can also suffer significant losses resulting from the non-adoption of environmental policies. In fact, firms that do not adopt environmental protection policies have their performance reduced by an average of 1.625 percentage points.