A dynamic hazard-based system of equations of vehicle ownership with endogenous long-term decision factors incorporating group decision making

The transportation system affects all aspects of our daily lives including relatively long-term decisions on work and home location choice and automobile ownership decisions. The interdependency existing among these three decisions jointly influences household mobility and overall travel patterns. Therefore, a dynamic modeling framework that can account for the effects of interdependencies between vehicle transaction behavior and residential and job location choices is highly desirable. These decisions are made in the household level while individuals’ decisions influence the overall outcome; therefore, it is also important to incorporate a group decision making process within such modeling frameworks.This study introduces a dynamic model for vehicle ownership, residential mobility, and employment relocation timing decisions. These decisions are modeled at the individual level and then sequentially aggregated to the household level if it is required. A hazard-based system of equations is formulated and applied in which work location and residential location changes are included as endogenous variables in the vehicle transaction model while other important factors such as land-use and built environment variables, household dynamics, and individuals’ socio-demographics are also considered.     

我国地区产业多样化、技术创新与经济发展--基于面板数据联立方程模型的研究

在分析我国地区产业多样化、技术创新与经济发展之间相互影响机制的基础上,构建联立方程组模型,并利用2003-2011年我国31个省份的面板数据进行实证检验。结果表明,产业多样化通过技术创新促进地区经济发展;相邻地区产业多样化与创新水平对地区经济发展影响显著为正,表明存在空间依赖效应;进一步将产业多样化划分为相关和无关多样化,发现相关多样化是创新产出的主要原动力,无关多样化的影响效应不显著。     

一种基于神经网络提取旋波材料参数的新方法

提出了一种从测试的S参数中提取旋波材料参数的新方法——神经网络法。针对旋波材料参数的自由空间测试方法,本文采用BP神经网络来构建映射模型,利用不同算法对网络进行训练,从而获得所需的网络。结果表明,该方法计算速度快、精度高,解决了求解非线性方程组解的模糊性问题,确保了测试结果的可靠性。该方法所构建的网络可用于材料测试后旋波材料参数的快速提取。     

On non-ergodic asset prices

We investigate the asset prices dynamics and the long-run market shares of two competing financial mediators who are selected by consumers. We demonstrate that the social interaction among consumers constitutes an endogenous path-depending source of risk in a financial market. Depending on consumers’ evaluation of the mediator’s investment, asset prices may behave in a non-ergodic manner: the price process converges in distribution but the limiting distribution is not necessarily uniquely determined, its multiplicity being characterized by the multiplicity of possible long-run market shares. The convergence of the process is sensitive to initial conditions and depends on the history of noise-trader transactions. Long-run portfolio holdings may be in-efficient since investors holding mean-variance efficient portfolios may not be identified.     

农业服务业与农业生产区域专业化的协同效应研究

[目的]探索农业服务业和农业生产区域专业化之间的相互关系,从而为农业服务业持续发展和农业生产区域专业化水平提升寻找可能路径。[方法]文章运用2003—2015年全国28个省的面板数据建立联立方程组模型检验农业服务业和农业生产区域专业化之间的协同效应。[结果](1)从全国层面来看,农业服务业产值增加1%使得农业生产的区域集中度指数提高0. 08%,结果在1%的水平上显著;前一期农业生产区域集中度指数提高1%使得当期农业服务业产值提高5. 348%,结果在5%的水平上显著;(2)西部地区农业服务业产值增加1%使得农业生产的区域集中度指数提高0. 342%,前一期农业生产区域集中度指数提高1%使得当期农业服务业产值提高7. 474%,结果分别在10%和5%的水平上显著;(3)东部地区农业服务业产值增加1%使得农业生产的区域集中度指数提高0. 099%,前一期农业生产区域集中度指数提高1%使得当期农业服务业产值提高5. 874%,结果均在5%的水平上显著;(4)中部地区农业服务业产值增加没有显著影响农业生产区域集中度指数,前一期农业生产区域集中度指数对当期农业服务业产值有5%水平上显著正向的影响,影响弹性为4. 531。[结论](1)农业服务业和农业生产区域专业化在全国层面表现出互相促进的协同效应,但是,该协同效应在东部、中部和西部地区表现出明显的差异;(2)西部地区农业服务业和生产区域专业化的协同效应最强烈;(3)东部地区农业服务业和生产区域专业化表现出协同效应,但不及西部强烈;(4)中部地区农业服务业和生产区域专业化没有表现出明显的协同效应。据此该文认为进一步优化农业产业布局应当重视农业服务业和区域生产专业化的协同效应及其地区差异。     

Measuring Structural Unemployment: NAWRU Estimates in the Nordic Countries

The non-accelerating wage rate of unemployment (NAWRU indicator), used by the OECD as a measure of structural unemployment, has risen for the four Nordic countries Denmark, Finland, Norway and Sweden. In this paper we present stable empirical wage equations for the same countries over the period 1964–1994, in sharp contrast to the increased NAWRU estimates. The instability of the NAWRU estimates is an artefact of a misspecified underlying wage equation, and not due to instability in wage setting itself.
JEL classification : E 24; E 31; E 64; J 51     

Optimal Consumption-Portfolio Policies With Habit Formation1

This is a companion paper to the authors ‘Asset Prices in an Exchange Economy with Habit Formation” in Econometrica which focuses on consumption demand and asset pricing when preferences are habit forming. Here we prove existence of optimal consumption-portfolio policies for (i) utility functions for which the marginal cost of consumption (MCC) interacts with the habit formation process and satisfies a recursive integral equation with forward functional Lipschitz integrand and (ii) utilities for which the MCC is independent of the standard of living and satisfies a recursive integral equation with locally Lipschitz integrand. Result (i) is demonstrated here for the first time. Result (ii) is novel and enables us to consider Cobb-Douglas utilities without placing lower bounds on the system of Arrow-Debreu prices. We also review and extend our earlier results in the linear case; in particular, we provide new insights about the structure of optimal portfolios. Additional new features of the model include the possibility of finite marginal utility of consumption at zero and habit formation mechanisms with stochastic coefficients. an extension to a financial market model with general processes is outlined. A byproduct of the analysis is a set of fixed-point theorems for recursive integral equations with forward functional Lipschitz or locally Lipschitz integrands.     

基于C语言对三次样条函数的求解及程序

在解三次样条函数时,最后都要归结为求解三对角型方程组。根据此类方程组的特点,该文介绍了一种追赶法,推导了使用这种方法的消元过程和回代过程,并给出了求解此类方程组的通用C语言程序,大大地节省了计算机工作量和计算机存贮单元。