Robust Markowitz mean‐variance portfolio selection under ambiguous covariance matrix

This paper studies a robust continuous‐time Markowitz portfolio selection problem where the model uncertainty affects the covariance matrix of multiple risky assets. This problem is formulated into a min–max mean‐variance problem over a set of nondominated probability measures that is solved by a McKean–Vlasov dynamic programming approach, which allows us to characterize the solution in terms of a Bellman–Isaacs equation in the Wasserstein space of probability measures. We provide explicit solutions for the optimal robust portfolio strategies and illustrate our results in the case of uncertain volatilities and ambiguous correlation between two risky assets. We then derive the robust efficient frontier in closed form, and obtain a lower bound for the Sharpe ratio of any robust efficient portfolio strategy. Finally, we compare the performance of Sharpe ratios for a robust investor and for an investor with a misspecified model.     

第三方支付相关基础法律问题探讨

第三方支付不是单纯的货币转移支付,而是与商业交易密切相关。互联网支付是典型的"担保支付",第三方为付款人的货币支付和收款人的货物交付进行了担保,有效保证了交易合同的全面履行,付款人支付的货币资金具有反担保保证金性质;预付卡支付和银行卡收单支付都是委托代理支付,预付卡支付第三方收到付款人的货币资金属于保管行为。     

传统白族民居如何适应现代功能需求——以沙溪白族民居为个案

沙溪的传统白族民居保存较好,数量庞大,既有大理白族民居的特点又有沙溪的地方特征。民居建筑材料为土、木、石。沙溪地区太阳辐射剧烈,冬季严寒,为提升室内舒适度,需要一些现代建筑技术手段来解决这些问题。随着社会的发展,为了适应现代化的生产方式,民居的功能空间发生了改变,并且伴着旅游开发,商业也作为一个不可缺少的因素融入到了沙溪民居中。     

Pareto-undominated and socially-maximal equilibria in non-atomic games

This paper makes the observation that a finite Bayesian game with diffused and disparate private information can be conceived of as a large game with a non-atomic continuum of players. By using this observation as its methodological point of departure, it shows that (i) a Bayes–Nash equilibrium (BNE) exists in a finite Bayesian game with private information if and only if a Nash equilibrium exists in the induced large game, and (ii) both Pareto-undominated and socially-maximal BNE exist in finite Bayesian games with private information. In particular, it shows these results to be a direct consequence of results for a version of a large game re-modeled for situations where different players may have different action sets.     

京津冀城市大气环境竞争力评价

从大气环境与城市竞争力的关联性入手,将大气环境风险、现状和治理纳入评价指标体系,基于组合权重的大气环境竞争力评价模型,对2013-2017年京津冀13个城市的大气环境竞争力水平进行了测评,并结合空间自相关分析和障碍度模型揭示了其空间效应及障碍因素。结果显示:京津冀城市大气环境竞争力存在明显的空间差异,呈"北部高、南部低、局部跳跃"格局,城市差距逐渐缩小;京津冀城市大气环境竞争力呈显著的空间集聚效应且存在正向相关性,空间分布格局相对稳定。     

Mapping Brisbane’s Casual Creative Corridor: Land use and policy implications of a new genre in urban creative ecosystems

Creative hotspots have become a key driver for urban policies to stimulate social, cultural, environmental and organisational growth of creative and knowledge-based clusters, districts and hubs. However, their functional and spatial characteristics vary due to their different evolving structure as new spaces of economic activity in different contexts. This article points to a consideration of new foci for both land use and urban economic policy through a mapping of formal and informal creative hotspots in Brisbane, Australia. The study found two distinctive development patterns: (a) earlier top-down approaches as instigated by national and international innovation policies, and; (b) recently emerging bottom-up spaces for creativity, knowledge and innovation practices. This study examines how formal creative strategies and emerging informal creative spaces shape cities and urban policies. The methodology comprises online data collection and a review of creative and knowledge strategies and implementation policies. Data was then analysed via multiple mapping techniques illustrating the spatial distribution of creative hotspots, formal and informal formations, scale and land use characteristics. The research findings consolidate our understanding of Brisbane’s creative ecosystem and suggest new urban policy mechanisms to better foster the interrelationship between top-down and bottom-up approaches in cities, that is, between formally planned and large-scale interventions and small-scale organic and informal creative activities.     

Bridging the valuescape with digital technology: A mixed methods study on customers’ value creation process in the physical retail space

This mixed methods study investigated how value is created in the physical retail space and how the customer experience is influenced by digital technology. A cross-sectional survey, with both qualitative and quantitative components, was distributed across a heterogeneous sample of 832 customers. The results revealed an overarching model comprised of three interrelated clusters: customer, service provider, and digital technology. We propose that this model can be understood as a valuescape, where customers' specific goals, needs, and desires drive them to interact and co-create value with service providers in the physical retail space, with digital technology either enhancing or disrupting this value co-creation process. The results also show that the importance of aligning digital solutions with customers’ drives increases at the same pace as reliance on technology. The findings offer guidelines on how to utilize digitalization to leverage customer experiences and thus strengthen the attractiveness of physical retail spaces.     

政府质量、科技创新与绿色GDP——中国省际空间溢出效应及区域差异对比

通过构建嵌入政府质量和科技创新因素的经济增长模型，利用中国30个省份2004~2017年的平衡面板数据，实证检验政府质量、科技创新对绿色GDP发展的影响。研究发现：中国绿色GDP存在显著的空间集聚性及明显的区域差异性。在经济权重矩阵影响下，不同地区的政府效率、市场化程度、公平程度和腐败程度对绿色GDP的影响不同，其中政府效率、公平程度能有效促进经济发展较好地区的绿色GDP增长，却会抑制比较落后地区绿色GDP的增长；市场化程度对大部分地区绿色GDP呈现促进作用；腐败程度对地区绿色GDP增长呈阻碍作用。科技创新对各地区绿色GDP均起到积极的促进作用。因此，提升绿色GDP发展水平不仅需要提高地方政府质量，为绿色GDP发展提供符合实际的政策指导意见，还需激活企业科技创新能力，为绿色GDP发展提供有力科技保障。     

混合型基金绩效评估及驱动因素分析——基于DEA-Tobit模型

将随机选出的混合型基金作为研究样本,采用DEA-Tobit二阶段模型进行研究.首先利用数据包络模型对样本进行绩效评估,在此基础上,利用Tobit模型研究相关指标对于基金绩效的影响机制.结果表明,基金本身所面临的风险收益因素以及基金经理团队稳定性对于基金绩效均具显著影响.最后结合实证结果就提升中国基金绩效提出相关的建议.     

聚丙烯物理改性的研究探讨

综述了聚丙烯物理改性的方法,并对共混改性、填充改性、混杂复合改性进行了比较。共混改性与填充改性虽可以改善聚丙烯的某一性能,如强度、韧性等,但对其他方面的提升有限,甚至使其他性能急剧下降。混杂复合改性中,聚丙烯与多种无机填料粒子、有机物复合,可以在明显提升某些性能的同时,维持其他性能稳定,甚至得到一定程度的提升,拓宽了聚丙烯的应用范围。