Complex Network of Aviation E-Services in the Belt and Road Initiative: A Heuristic Study of Small Data based on Block Modeling

ABSTRACT

The aviation e-service system is an important part of support for business communication in regions covered by Belt and Road initiative. In exploring the role of airline companies in this system, we examine the structure of the network, which consists of airlines interconnections based on small data of individual attributes of aviation companies in aviation e-services, and study these interconnections across different groups using block modeling. The heuristic solution of airline companies in development of international communication and cooperation is further discussed. Among our policy implications for global managers, we suggest the enhancement of cross-regional cooperation among airlines.     

EMPIRICAL PERFORMANCE OF GARCH MODELS WITH HEAVY‐TAILED INNOVATIONS

We introduce a new type of heavy‐tailed distribution, the normal reciprocal inverse Gaussian distribution (NRIG), to the GARCH and Glosten‐Jagannathan‐Runkle (1993) GARCH models, and compare its empirical performance with two other popular types of heavy‐tailed distribution, the Student's t distribution and the normal inverse Gaussian distribution (NIG), using a variety of asset return series. Our results illustrate that there is no overwhelmingly dominant distribution in fitting the data under the GARCH framework, although the NRIG distribution performs slightly better than the other two types of distribution. For market indexes series, it is important to introduce both GJR‐terms and the NRIG distribution to improve the models’ performance, but it is ambiguous for individual stock prices series. Our results also show the GJR‐GARCH NRIG model has practical advantages in quantitative risk management. Finally, the convergence of numerical solutions in maximum‐likelihood estimation of GARCH and GJR‐GARCH models with the three types of heavy‐tailed distribution is investigated.     

Optimal investment with vintage capital: Equilibrium distributions

The paper concerns the study of equilibrium points, or steady states, of economic systems arising in modeling optimal investment with vintage capital, namely, systems where all key variables (capitals, investments, prices) are indexed not only by time but also by age. Capital accumulation is hence described as a partial differential equation (briefly, PDE), and equilibrium points are in fact equilibrium distributions in the variable of ages. A general method is developed to compute and study equilibrium points of a wide range of infinite dimensional, infinite horizon, optimal control problems. We apply the method to optimal investment with vintage capital, for a variety of data, deriving existence and uniqueness of equilibrium distribution, as well as analytic formulas for optimal controls and trajectories in the long run. The examples suggest that the same method can be applied to other economic problems displaying heterogeneity. This shows how effective the theoretical machinery of optimal control in infinite dimension is in computing explicitly equilibrium distributions. To this extent, the results of this work constitute a first crucial step towards a thorough understanding of the behavior of optimal paths in the long run.     

深圳市线路板蚀刻废液中铜、砷、铅、汞、镉含量调查

对深圳市60家线路板企业含铜蚀刻废液中铜、砷、铅、汞、镉含量的检测结果显示:酸、碱性蚀刻废液铜含量范围分别为38.6～167.9g/L、53.7～171.8g/L,,通过测量比重推算铜含量适用于碱性废液但不适合酸性废液.56个样品可检出砷(大于3mg/L).56个样品未检出铅(小于5mg/L),其余4个铅含量偏高.所有样品汞、镉均未检出,含量分别小于4mg/L、0.3 mg/L.将各样品砷、铅、汞、镉含量实测值换算为铜含量100ga.时的相对值后发现,上述四元素在蚀刻废液中的正常值分别为＜12mgAs/L、＜5 mg Pb/L、＜4 mg Hg/L、＜0.3 mg Cd/L.     

浅谈企业房地产价值信息的背离与披露

房地产交易中企业财务报告反映的房地产账面价值与实际市场价值的背离程度大,造成了企业资产价值的“低估”。该文试图分析引起企业房地产账面价值与实际市场价值背离的原因,提出了财务报告使用者了解企业房地产实际价值的几种可操作方法。     

A note on the existence of unique equivalent martingale measures in a Markovian setting

Simple sufficient conditions for the existence of a unique equivalent martingale measure are provided. Furthermore, these conditions give us a handle on situations where an equivalent martingale measure cannot exist. The existence of a unique equivalent martingale measure is of relevance to problems in mathematical finance. Two examples of models for which the question of existence was unresolved are studied. By means of our results existence of a unique equivalent measure up to an explosion time is proved.     

国际电子商务中的语言差异问题及其解决策略

在电子商务的全球化过程中，各地区的语言、文化差异。给国际电子商务展开带来了一定的障碍，本文论述了语言问题产生的根源，并提出了相应的解决策略，以期对国内企业的未来发展有所助益。     

中日韩自由贸易区的贸易流量和福利效应分析:一个局部均衡的校准方法

校准方法作为一种确定数理经济模型中的变量和参数的手段之一,在贸易政策的建模研究中得到广泛的应用.本文以局部均衡为基础,利用中日韩三国自1990～2003年共14年的贸易额及相关数据建立校准模型,并对拟议中的中日韩自由贸易区做出比较静态分析,从产业层面来模拟中日韩自由贸易区建成后所可能带来的福利效应.分析结果表明,中日韩三国建立自由贸易区会增加彼此的国民福利水平,并会对未加入贸易协定的其他东亚国家产生影响.因此,在东亚形成更为广泛的自由贸易安排从区域合作的角度来看是一种更佳的合作方式.     

我国危险品物流管理对策研究

通过对我国危险品物流的现状分析,指出了加强危险品物流管理的必要性,并阐述了加强危险品物流管理的意义。在对国外危险品物流管理方法进行总结的基础上,分析了我国政府和危险品物流企业在危险品物流管理中的作用和相互关系,并提出了加强危险品物流管理的一些具体对策和措施。     

区域经济学主流化的新格局:迈向新综合的空间一般均衡理论

区域经济学的研究从1990年后，日趋活跃、争论纷呈，在某种意义上讲，发生了很大的转向。即由克鲁格曼发轫的新经济地理把该领域的某些问题带向经济学主流的一般均衡分析框架下来讨论，他们更加宏伟的蓝图是要实现具有新综合特征的空间一般均衡理论，为区域经济学的研究注入了新的活力。该文简述了这些新理论的基本模型、主要特征和模型的扩展及对经济体系空间特性研究的主要贡献，以及由之而引起的各方面的争论和共识。