Quasiperiodic Solutions in Weakly Nonlinear Gas Dynamics. Part I. Numerical Results in the Inviscid Case

We exhibit and study a new class of solutions for the one-dimensional inviscid Euler equations of Gas Dynamics in a bounded domain with reflecting boundary conditions, in the weakly nonlinear regime. These solutions do not present the usual wave breaking leading to shock formation, even though they have nontrivial acoustic components and operate in the nonlinear regime. We also show that these 'Non Breaking for All Times' (NBAT) solutions are globally attracting for the long time evolution of the equations.
The Euler equations of Gas Dynamics (in the weakly nonlinear regime with reflecting boundary conditions) can be reduced to an inviscid Burgers-like equation for the acoustic component, with a linear integral self-coupling term and periodic boundary conditions. The integral term arises as a result of the nonlinear resonant interactions of the sound waves with the entropy variations in the flow. This integral term turns out to be weakly dispersive. The NBAT solutions arise as a result of the interplay of this dispersion with the 'standard' wave-breaking nonlinearity in the Burgers equation.
In addition to the previously known weakly nonlinear standing acoustic wave NBAT solutions, we found a family of new, never-breaking, attracting solutions by direct numerical simulation. These are quasiperiodic in time with two periods. In phase space these solutions lie on a surface 'centered' around the standing waves. Only two standing-wave solutions (the maximum amplitude and the trivial vanishing wave) are in the attracting set. All of the others are quasiperiodic in time with two periods.     

A problem of the fastest detection of regime changing for Levy processes

The optimal stopping time for the fastest regime change (disorder) detection problem in the generalized Bayesian setting is determined for an arbitrary Levy process.     

基于logit回归模型的顾客资产驱动因素与忠诚意向关系实证研究

国内关于顾客资产驱动因素模型的实证研究较少.将顾客资产三大驱动因素(价值资产、品牌资产和关系资产)与忠诚意向联系起来,用我国银行业688个数据进行了Logit回归建模,研究顾客资产驱动因素分别与忠诚意向之间的关系、驱动因素两两之间的关系以及顾客资产驱动因素组合对忠诚意向产生的协同效应.研究结论表明,首先,价值资产、品牌资产、关系资产均对顾客忠诚意向产生显著正影响;其次,品牌资产对关系资产和价值资产均产生显著正影响,但价值资产对关系资产的直接影响不显著,这可能是因为品牌资产在价值资产和关系资产之间的中介作用;最后,同时投资价值资产和品牌资产或同时投资关系资产和品牌资产反而会使顾客忠诚意向降低.研究结论能够为银行管理者优化营销经费配置提供理论支持.     

基于报表数据的上市公司顾客资产测量与提升——中国联通公司的应用研究

顾客资产体现企业在市场竞争中获取顾客资源的能力,本研究旨在利用报表数据对上市公司的顾客资产进行测量,并依据测量结果提出提升策略。首先,运用Matlab编程模拟上市公司的每期期末顾客存量适用的技术替代模型,进而求得顾客资产。其次,依据β转换模型原理估算企业现有顾客的终身价值总和,在同时考虑顾客的获取与流失的前提下求得顾客资产可持续比率。再次,依据顾客资产可持续比率和顾客资产的计算结果构建二维坐标图,以分析企业顾客资产的时间序列特征,作为提升顾客资产的依据。最后,将该方法在中国联通公司进行了应用。研究结果表明,该方法对上市公司的顾客资产测量和提升具有较好的适用性和可操作性。研究结果对于上市公司的顾客资产管理具有一定的参考价值。     

A Matched Asymptotic Expansions Approach to Continuity Corrections for Discretely Sampled Options. Part 1: Barrier Options

We propose a general framework to model equity volatility for a firm financed by equity and additional non-equity sources of funds. The stochastic nature of equity volatility is endogenous, and comes from the impact of a change in the value of the firm's assets on the financial leverage. We first present the basic model, which is an extension of the Black-Scholes model, to value corporate securities. Second, we show for the first time in the option literature, that instantaneous equity volatility is a solution of a partial differential equation similar to Black-Scholes', although it is non-linear and in general does not have any analytical solution. However, analytical approximations for equity volatility are proposed for different capital structures: (1) equity and debt, (2) equity and warrants, and (3) equity, debt and warrants. They are shown to be very accurate.     

品牌资产与品牌价值关联模型的实证研究

现如今,品牌资产与品牌价值在企业经济活动中扮演的角色日益重要,二者的概念、特征以及作用机制等越来越被学者和企业界所重视,但聚焦品牌资产与品牌价值关联关系的研究仍然较为缺乏.通过对品牌资产与品牌价值的概念界定,依据品牌资产的作用机制和品牌价值的形成机理,构建了二者的关联理论模型,并通过实践调研对这一问题进行了实证研究,结果表明品牌资产通过调节效应能够驱动品牌价值的形成,最后为企业如何杠杆品牌资产实现品牌价值提出了相关管理启示.     

农村卫生资源配置公平性研究——基于2003-2005年黑龙江省13个地区的数据分析

运用多种评价指标研究黑龙江省农村卫生资源配置公平性,发现黑龙江省十三个地区各类卫生资源的三种公平性指数高度一致;卫生资源主要是按人口分布配置的,且公平性在逐渐降低;哈尔滨市、绥化市等地区资源配置公平性较高.同时显示政府的认识和重视程度影响资源配置的公平性.     

Queues with random back-offs

We consider a broad class of queueing models with random state-dependent vacation periods, which arise in the analysis of queue-based back-off algorithms in wireless random-access networks. In contrast to conventional models, the vacation periods may be initiated after each service completion, and can be randomly terminated with certain probabilities that depend on the queue length. We first present exact queue-length and delay results for some specific cases and we derive stochastic bounds for a much richer set of scenarios. Using these, together with stochastic relations between systems with different vacation disciplines, we examine the scaled queue length and delay in a heavy-traffic regime, and demonstrate a sharp trichotomy, depending on how the activation rate and vacation probability behave as function of the queue length. In particular, the effect of the vacation periods may either (i) completely vanish in heavy-traffic conditions, (ii) contribute an additional term to the queue lengths and delays of similar magnitude, or even (iii) give rise to an order-of-magnitude increase. The heavy-traffic trichotomy provides valuable insight into the impact of the back-off algorithms on the delay performance in wireless random-access networks.     

Inquiry as an entry point to equity in the classroom

ABSTRACT

Although many policy documents include equity as part of mathematics education standards and principles, researchers continue to explore means by which equity might be supported in classrooms and at the institutional level. Teaching practices that include opportunities for students to engage in active learning have been proposed to address equity. In this paper, through aligning some characteristics of inquiry put forth by Cook, Murphy and Fukawa-Connelly with Gutiérrez's dimensions of equity, we theoretically explore the ways in which active learning teaching practices that focus on inquiry could support equity in the classroom.     

State-of-the-Art in Sequential Change-Point Detection

We provide an overview of the state-of-the-art in the area of sequential change-point detection assuming discrete time and known pre- and post-change distributions. The overview spans over all major formulations of the underlying optimization problem, namely, Bayesian, generalized Bayesian, and minimax. We pay particular attention to the latest advances in each. Also, we link together the generalized Bayesian problem with multi-cyclic disorder detection in a stationary regime when the change occurs at a distant time horizon. We conclude with two case studies to illustrate the cutting edge of the field at work.     

German mathematicians in exile in Turkey: Richard von Mises,William Prager,Hilda Geiringer,and their impact on Turkish mathematics

There is a sizable and growing literature on scholars who fled from the Nazi regime, a literature which often focuses on the periods before leaving Germany and after settling permanently in the USA, but relatively less work on the interim period in which many of them found temporary homes in countries such as Turkey. In this article we would like to discuss the scholarly work, activities and the impact of mathematicians Richard von Mises, William Prager and Hilda Geiringer during their stay in Turkey. We argue that the establishment and the development of applied mathematics and mechanics in Turkey owe much to them.     

状态转移下的利率预期与误差学习假说

采用线性回归和状态转移模型讨论利率预期的"误差学习假说"和不同期限利率预测误差之间的关联性,并考虑带有风险溢价时预测误差的作用.分析发现,1年期限的"误差学习假说"在银行间国债市场中是成立的,不同期限的利率预期对预测误差的反应呈现一定的独立性,不同的状态中预测误差和风险溢价对利率预期的影响是不同的,考虑风险溢价有助于提升对利率预期变动的解释.     

直接资本化法中自有资本收益率的算法探讨

在分析我国房地产自有资本收益率操作中所存在问题的基础上,论述了自有资本收益率的实质是自有资金直接资本化率,并在房地产持有期小于抵押贷款期以及房地产持有期和土地批租年限相同的两种情况下,推导出了与土地有限期使用制度相适应的房地产资本化率和自有资本收益率的计算方法,提出了利用债务保障比率的取值范围检验资本化率合理性的基本公式.     

American options and stochastic interest rates

We study finite-maturity American equity options in a stochastic mean-reverting diffusive interest rate framework. We allow for a non-zero correlation between the innovations driving the equity price and the interest rate. Importantly, we also allow for the interest rate to assume negative values, which is the case for some investment grade government bonds in Europe in recent years. In this setting we focus on American equity call and put options and characterize analytically their two-dimensional free boundary, i.e. the underlying equity and the interest rate values that trigger the optimal exercise of the option before maturity. We show that non-standard double continuation regions may appear, extending the findings documented in the literature in a constant interest rate framework. Moreover, we contribute by developing a bivariate discretization of the equity price and interest rate processes that converges in distribution as the time step shrinks. This discretization, described by a recombining quadrinomial tree, allows us to compute American equity options’ prices and to analyze their free boundaries with respect to time and current interest rate. Finally, we document the existence of non-standard optimal exercise policies for American call options on a non-dividend-paying equity.

     

股权激励与公司绩效：基于调整成本

文章从调整成本角度出发,运用广义矩估计法重新审视股权激励与公司绩效之间的关系,并寻找调整成本的决定因素．在不考虑调整成本的传统模型下,公司绩效对于股权激励有显著的负向影响,但考虑调整成本后影响不再显著;在决定因素方面,股权激励的调整速度与机构投资者持股比例、高管数量以及市场价格正相关,公司绩效的调整速度与沉没成本正相关而与公司定价能力负相关．     

公平关切下参照价格效应的绿色供应链定价策略

以制造商主导的由一个制造商和一个零售商组成的绿色供应链为研究对象,基于消费者的参照价格构造了制造商公平关切、零售商公平关切和供应链成员均公平关切三种供应链模型,给出各模型下的最优定价策略,并分析了公平关切系数与消费者的参照价格效应对最优策略的影响。研究结果表明:公平关切系数与消费者的参照价格效应改变了产品的批发价格、绿色度水平和零售价格,且对供应链各成员以及整个供应链系统都产生了影响。     

A new methodology for studying the equity premium

This paper provides a new framework for the derivation and estimation of consumption and equity premium functions. Applying duality in a dynamic context, we show that equity premium and consumption functions can be easily obtained from the indirect utility function. Our new framework, therefore, does not require explicit specification of underlying consumer preferences. Using aggregate US data (1929–2000) we estimate the consumption and equity premium functions using a nonparametric technique. We find that the model does well in explaining the observed smooth consumption patterns and does reasonably well in explaining the high mean and volatility of equity premia.     

成长性差异、信息披露与权益资本成本

本文研究成长性差异是否以及如何影响信息披露与权益资本成本之间的关系。实证结果表明成长性差异可以显著调节信息披露与权益资本成本之间的关系,利用分组回归分析法发现,高成长性上市公司信息披露水平越高,权益资本成本越低。进一步研究发现,在高成长性样本组中,非国有控股上市公司信息披露对权益资本成本的影响相对显著,而在低成长性样本组中,国有控股上市公司信息披露对权益资本成本的影响相对显著。在采用工具变量法和两阶段最小二乘法等(2SLS)进行一系列稳健性检验之后,上述结论仍然成立。本文的研究结论为上市公司和监管机构完善信息披露制度提供一定的启示。     

Socio-economic and cultural mediators of mathematics achievement and between-school equity in mathematics education at the global level

This paper aims at identifying and understanding how and to what extent socioeconomic and cultural factors mediate mathematics achievement and between-school equity in mathematics education among countries. First, under the assumption that equity and quality of education are independent constructs, the construct of equity-in-quality in mathematics education is developed. Second, the 18 countries that were identified in the previous work of the author Jurdak in (Toward equity in quality in mathematics education. Springer, New York, 2009) as being diverse in mathematics education will serve as study cases to illustrate, compare, and contrast the mediatory role of socio-economic and cultural factors in mathematics achievement and between-school equity in mathematics education. The results show that the differences in mathematics achievement and between-school equity in mathematics education at the country level are associated with, and can be accounted for in some cases, by socioeconomic and cultural factors.     

An analytical model for building brand equity in hospitality firms

Nowadays, service-oriented marketing has been playing an important role in marketing science fields. The current studies have focused on the establishment of a brand equity model and the relevant causal relationships of the model, they have not presented any consistent measurement technique. Hence, this paper aims to standardize the estimation of a constructed dimension for the equity of service-oriented brands and to solve the multiple-dimension problem inherent in this estimation. In particular, this proposed analytical model considers distinct weights for brand equity categories and attributes. Further, we intend to systematically present a deliberate procedure of the brand equity model along with a strategy to enable the further development of this procedure. By adopting quality function deployment (QFD) and consistent fuzzy preference relations, we create a valid and reliable brand equity model for hospitality firms. Finally, we empirically assess the measurement and managerial strategies related to the proposed model by illustrating the case of a restaurant chain.