基于次梯度投影的泛投资组合选择策略

在线投资组合选择(online portfolio selection)问题是当前量化投资领域一个重要的研究问题.近些年来,可投资标的的爆炸式增长急需能够有效计算的投资组合选择策略,而现有高绩效算法大多具有指数级或多项式级的时间复杂度,不利于在实际中应用.由此,本文提出了一种基于次梯度投影的泛投资组合选择策略SGP.将次梯度投影的思想应用到资产组合构建的过程中,得到策略的再平衡规则.理论上,本文分析了次梯度投影算法的竞争性能,证明了该策略是一个泛投资组合选择策略;并发现该算法具有线性时间复杂度.实证上,验证了SGP策略在美国与中国市场的表现.结果表明,SGP策略能够实现和最新的泛投资组合选择策略相当的收益率,而算法运行时间短于现有策略.参数敏感性分析表明SGP策略对参数选择不敏感;交易成本敏感性分析表明SGP策略能够承受合理的交易成本.     

Probabilistic population projections for countries with generalized HIV/AIDS epidemics

In 2015, the United Nations (UN) issued probabilistic population projections for all countries up to 2100, by simulating future levels of total fertility and life expectancy and combining the results using a standard cohort component projection method. For the 40 countries with generalized HIV/AIDS epidemics, the mortality projections used the Spectrum/Estimation and Projection Package (EPP) model, a complex, multistate model designed for short-term projections of policy-relevant quantities for the epidemic. We propose a simpler approach that is more compatible with existing UN projection methods for other countries. Changes in life expectancy are projected probabilistically using a simple time series regression and then converted to age- and sex-specific mortality rates using model life tables designed for countries with HIV/AIDS epidemics. These are then input to the cohort component method, as for other countries. The method performed well in an out-of-sample cross-validation experiment. It gives similar short-run projections to Spectrum/EPP, while being simpler and avoiding multistate modelling.     

《给——温柔的歌声已消逝》中的爱情“外衣”——基于概念隐喻视角

隐喻是构成诗歌体裁特征的重要要素,许多重要诗论也论证过诗性隐喻对于提高认知能力和反映认知现象的重要意义。概念隐喻认为隐喻是一种认知手段,是理解世界、产生意义的重要途径。其本质是概念性的,是跨概念域的系统映射。雪莱的《给——温柔的歌声已消逝》通过对歌声和音乐、芳香和紫罗兰等具体概念的描述,映射到与思维情感相关的抽象概念上,生动地传达出了留恋逝去爱情的强烈感受,为无形的爱情穿上了一件有形的外衣。运用概念隐喻理论对该诗歌进行分析,不仅能够给予理解这首诗歌一个更加新颖的视角,更能对隐喻传达抽象情感有更加具体的认识。     

Variable selection for semiparametric proportional hazards model under progressive Type-II censoring

Variable selection is an effective methodology for dealing with models with numerous covariates. We consider the methods of variable selection for semiparametric Cox proportional hazards model under the progressive Type-II censoring scheme. The Cox proportional hazards model is used to model the influence coefficients of the environmental covariates. By applying Breslow’s “least information” idea, we obtain a profile likelihood function to estimate the coefficients. Lasso-type penalized profile likelihood estimation as well as stepwise variable selection method are explored as means to find the important covariates. Numerical simulations are conducted and Veteran’s Administration Lung Cancer data are exploited to evaluate the performance of the proposed method.     

一类新的广义变分包含系统及其迭代算法

在Banach空间中介绍了一类新的广义变分包含系统.利用松弛增生映象及预解算子,证明了该广义变分包含系统解的存在性和唯一性,同时也建立了收敛于该唯一解的迭代算法,并给出相应的迭代收敛定理.     

2015年国际原油价格分析与趋势预测

在回顾2014年国际原油市场主要发展历程的基础上,从两方面对2015年油价走势进行了发展态势展望和预测分析。研究认为:受全球经济形势复杂多变,复苏进程缓慢、脆弱而不均衡以及供需基本面因素的主要作用,在产量相对过剩情况下,2015年油价上半年依旧延续下跌趋势,国际原油价格还将在低位震荡,下半年或出现企稳反弹,全年油价波动幅度小于2014年。预计Brent原油均价为50~65美元/桶,WTI原油均价为45~60美元/桶。     

电信市场差别定价中的反垄断问题

我国电信业已基本形成三家国有综合电信运营商竞争的市场格局,但市场结构欠合理,存在一些垄断行为及监管制度的缺陷。《反垄断法》出台后,电信运营商通过差别定价进行市场营销已成为是否违反《反垄断法》讨论的重点,也成为消费投诉的集中指向。基于SCP的研究框架,对电信市场的竞争结构、行为与绩效进行研究,以确定电信公司的垄断性质;针对不同差别定价对市场结构及消费者福利的影响,提出要区别对待电信市场营销中存在的不同形式的差别定价,施以相应的监管方式;并且要建立主导运营商的监管体系,以防止其滥用市场竞争地位;同时要将电信监管与反垄断监管相结合,共同监管电信市场的反竞争行为。     

国有企业经营者选拔中的难题及解决思路

民营企业的创业过程与企业家形成过程是统一的,而国有企业往往是先有企业后有经营者的。从理论和实践上看,国有企业经营者选拔中存在诸多难题,它体现在风险承担的不对称、信息缺陷严重、选拔标准在实践中扭曲、经营者身份的准官员化、能力信号显示与专用性知识投资之间的突出矛盾上。如果不能很好地解决这些问题,任何意义上的国有企业改革都不可能取得实效。为此,要通过对国企准确定位,区分不同类型的经营者,政府主动"淡出"选拔过程与相机干预相结合,发挥机构投资者的作用及发展完善的经理市场来加以优化。     

Is demography destiny? The role of structural and demographic factors in Australis past and future labour supply

Following the release of the Intergenerational Report, the Australian Treasury identified the levers to address the economic effects of demographic ageing as ‘the three Ps’: population, participation and productivity. To date, the first ‘P’, population, has been treated as an exogenous factor, with the common view being that there is very little that the government can do to supplant demographic ageing. Focusing upon labour supply, this paper shows how variation in Australia’s underlying demography can significantly alter Australia’s future labour supply. Although governments cannot redirect the cohort flow component of population ageing, much can be achieved in promoting growth of the labour supply by maintaining or increasing fertility (in the longer term), or increasing targeted migration (in the short to medium term). This paper also decomposes the relative role of cohort flow, changing demography and changing labour force participation on the growth of the labour supply over the past 20 years. Over this period, the entry of the baby boom generation (cohort flow) and increased labour force participation of women accounted for almost all of the growth in the labour force. Changing demography had very little effect. However, Australias future labour supply will not include a large increase in cohort flow (as caused by the baby boomers) or a very large increase in female labour force participation. Regardless of the assumptions used, labour supply growth will be considerably lower in the next and subsequent 20 years, when compared to the previous 20.