Optimal dividend payments in the classical risk model when payments are subject to both transaction costs and taxes

In this paper, we study optimal dividend problem in the classical risk model. Transaction costs and taxes are required when dividends occur. The problem is formulated as a stochastic impulse control problem. By solving the corresponding quasi-variational inequality, we obtain the analytical solutions of the optimal return function and the optimal dividend strategy when claims are exponentially distributed. We also find a formula for the expected time between dividends. The results show that, as the dividend tax rate decreases, it is optimal for the shareholders to receive smaller but more frequent dividend payments.     

独立监事能减少企业违规行为吗？——基于“四大”审计的中介效应分析

监事会的职责之一是监督公司和高管的行为,因此需要保持相对独立,然而我国监事会一直存在独立性较弱的问题。以A股上市公司2009—2019年的数据为研究样本,检验以不领薪为特征的独立监事对公司违规行为的影响,并研究企业聘请“四大”会计师事务所审计的影响机制。实证结果表明：独立监事能有效减少企业违规行为并促进企业获取更高质量的审计。根据影响机制研究可知,聘请“四大”会计师事务所审计在独立监事与企业违规之间的关系中起中介作用。进一步研究的结果表明,当内部控制薄弱、监事会较为活跃时,独立监事监督效果会更好。     

空气钻井中钻柱扭转振动的计算

空气钻井是指钻进过程中循环介质为空气的钻井。空气钻井有利于提高钻井速度,缩短建井周期,降低钻井总成本;能很好的保护产层,但其处理地层出水的能力差;井壁不稳定;井底欠压值太大,处于无控制的欠平衡状态,导致储层速敏、出砂,甚至坍塌;钻具失效问题严重。本文在理论分析的基础上,对各种振动进行了较好的数值分析。研究表明,整体钻柱的扭转振动特性受钻柱规格以及长度影响。长度增加,钻柱相应各阶固有频率显著降低。计入钻井液附加质量效应后,钻柱的各阶固有频率显著降低。分析表明,钻井液阻尼对钻柱动力安全性有一定的积极意义。     

FDD LTE上行系统的频偏估计方案及实现

针对LTE系统对频偏十分敏感这一缺点,根据同一子载波在不同时刻由于频偏的存在导致相位偏转不同的特点,本文详细推导了一种基于导频的小数部分的频偏估计方案。通过仿真验证了此频偏估计方案在瑞利多径衰落信道下能实现较精确的频率跟踪。将此方案经优化移植到DSP平台上,通过测试,验证了在实际系统中同样能对子载波的频偏做出精确的估计,且能满足系统性能需求。     

浅谈电力线载波通信技术

电力线载波通信作为一门古老而年轻的通信技术,广泛地应用在各种通信领域中。中低压电力线载波通信技术因其具有建设成本低、无须另外布线等天然的优势,在配网自动化系统、大用户抄表系统、低压抄表系统以及农村地区宽带网络接入等方面被业内人士看好,其发展潜力巨大。     

On the jump activity index for semimartingales

Empirical evidence of asset price discontinuities or “jumps” in financial markets has been well documented in the literature. Recently, Aït-Sahalia and Jacod (2009b) defined a general “jump activity index” to describe the degree of jump activities for asset price semimartingales, and provided a consistent estimator when the underlying process contains both a continuous and a jump component. However, only large increments were used in their estimator so that the effective sample size is very small even for large sample sizes. In this paper, we explore ways to improve the Aït-Sahalia and Jacod estimator by making use of all increments, large and small. The improvement is verified through simulations. A real example is also given.     

投标人参考点效应与最优公开保留价博弈分析

本文从行为经济学出发,用博弈论的方法研究存在参考点效应时,投标人在第一价格和第二价格密封招标中的报价策略以及招标人的最优公开保留价定价策略,并对不同招标方式下投标人的期望收益进行比较。本文给出存在参考点效应时招标最优公开保留价的定价公式,分析了参考点效应和投标人数对最优公开保留价的影响。研究表明,在采用公开保留价的情况下,考虑投标人参考点效应对报价策略的影响时,不同招标方式给投标人带来的期望收益是相等的,即此时招标支付等价性命题仍然成立。此外,随着投标人参考点效应的增强和投标人数的增加,招标人的最优公开保留价下降。     

Computing optimal rebalance frequency for log-optimal portfolios

Log-optimal investment portfolio is deemed to be impractical and cost-prohibitive due to inherent need for continuous rebalancing and significant overhead of trading cost. We study the question of how often a log-optimal portfolio should be rebalanced for any given finite investment horizon. We develop an analytical framework to compute the expected log of portfolio growth when a given discrete-time periodic rebalance frequency is used. For a certain class of portfolio assets, we compute the optimal rebalance frequency. We show that it is possible to improve investor log utility using this quasi-passive or hybrid rebalancing strategy. Simulation studies show that an investor shall gain significantly by rebalancing periodically in discrete time, overcoming the limitations of continuous rebalancing.     

矢量控制在异步电动机变频调速中的应用

变频器的功能是将频率固定的(通常为50Hz)的交流电变换成频率连续可调的三相交流电源。现简要论述一下矢量控制在异步电动机变频调速中的应用。     

Luxury shopping in tourism

This study explores the concept of luxury shopping behaviour in tourism and identifies the perceived importance of different types and characteristics of the luxury products and services that tourists buy on vacation, as well as the importance of various shopping venues and destinations for luxury shopping. The study examines the significant differences in luxury purchasing patterns among various types of tourists identified on the basis of the frequency of shopping and the degree of importance attached to shopping. The results show that three groups, infrequent shoppers, sometimes shoppers and frequent shoppers, as well as non‐shoppers, neutral shoppers and great shoppers, significantly differ in their luxury shopping behaviour. The implications of study results and recommendations for future studies are discussed. Copyright © 2009 John Wiley & Sons, Ltd.