Infinite-dimensional VARs and factor models

This paper proposes a novel approach for dealing with the ‘curse of dimensionality’ in the case of infinite-dimensional vector autoregressive (IVAR) models. It is assumed that each unit or variable in the IVAR is related to a small number of neighbors and a large number of non-neighbors. The neighborhood effects are fixed and do not change with the number of units (N), but the coefficients of non-neighboring units are restricted to vanish in the limit as N tends to infinity. Problems of estimation and inference in a stationary IVAR model with an unknown number of unobserved common factors are investigated. A cross-section augmented least-squares (CALS) estimator is proposed and its asymptotic distribution is derived. Satisfactory small-sample properties are documented by Monte Carlo experiments. An empirical illustration shows the statistical significance of dynamic spillover effects in modeling of US real house prices across the neighboring states.     

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。     

转子磁链定向的矢量控制系统的研究

利用计算机仿真技术simulink对直接矢量控制系统进行分析研究,仿真结果表明按转子磁链定向的矢量控制系统克服了磁链开环系统的缺点,提高了系统的动态性能,这种系统具有广泛的实用价值。     

关于单位内部控制的辨析

内部控制是一个能动的驾御,监测和推动系统,它与单位的未来息息相关,目前,我国还没有一个统一或固定模式,需要不断探索,实践,不断完善。内部控制建设任重而道远。     

News shock,firm dynamics and business cycles: Evidence and theory

The literature of expectation-driven business cycles has overlooked the role played by endogenous entry. This paper documents empirically news shock as a major source of fluctuations in firm dynamics and comovement between firm entry and GDP using structural vector auto-regressions. We then develop a tractable dynamic stochastic general equilibrium model to study the propagation mechanism assuming fixed operating costs for incumbents and decreasing survival rates for entrants. Our quantitative prediction closely matches the positive comovement between firm entries and core macroeconomic indicators upon news shock. These results remain robust at the sectoral level when the baseline model is extended to a two-sector setup.     

基于自适应模糊神经网络PID控制器的主动队列管理算法

主动队列管理(AMQ)是一种非常重要的拥塞控制的研究领域。但其自身的复杂性和计算机网络的动态特性,传统的PID控制算法由于其固定参数的方式、导致其对动态环境适应性低。为了克服这些缺点,通过对拥塞智能控制理论的研究,介绍了一个新的AQM算法FAPIDNN。模糊控制器是采用自动学习速率η的计算机,通过神经网络PID控制器根据当前网络状态和对网络数据包下降概率的计算基础上,网络速率自主学习的模糊控制器。仿真结果表明FAPIDNN算法在队列稳定、收敛速度和时间延迟上要优于PID控制器。     

Transfer Payments without Growth: Evidence for German Regions, 1992–2005

After German reunification, interregional subsidies accounted for approximately 4% of gross fixed capital investment in the new federal states (i.e. those which were formerly part of the German Democratic Republic). We show that, between 1992 and 2005, infrastructure and corporate investment subsidies had a negative net impact on regional economic growth and convergence. This result is robust to both the specification of spatially weighted control variables and the use of instrumental variable techniques to control for the endogeneity of subsidies. Our results suggest that regional redistribution was ineffective, potentially due to a lack of spatial concentration to create growth poles.     

Prediction in the Panel Data Model with Spatial Correlation: the Case of Liquor

Abstract

This paper considers the problem of prediction in a panel data regression model with spatial autocorrelation in the context of a simple demand equation for liquor. This is based on a panel of 43 states over the period 1965–1994. The spatial autocorrelation due to neighbouring states and the individual heterogeneity across states is taken explicitly into account. We compare the performance of several predictors of the states’ demand for liquor for 1 year and 5 years ahead. The estimators whose predictions are compared include OLS, fixed effects ignoring spatial correlation, fixed effects with spatial correlation, random-effects GLS estimator ignoring spatial correlation and random-effects estimator accounting for the spatial correlation. Based on RMSE forecast performance, estimators that take into account spatial correlation and heterogeneity across the states perform the best for forecasts 1 year ahead. However, for forecasts 2–5 years ahead, estimators that take into account the heterogeneity across the states yield the best forecasts.     

Estimation for spatial dynamic panel data with fixed effects: The case of spatial cointegration

Yu et al. (2008) establish asymptotic properties of quasi-maximum likelihood estimators for a stable spatial dynamic panel model with fixed effects when both the number of individuals n and the number of time periods T are large. This paper investigates unstable cases where there are unit roots generated by temporal and spatial correlations. We focus on the spatial cointegration model where some eigenvalues of the data generating process are equal to 1 and the outcomes of spatial units are cointegrated as in a vector autoregressive system. The asymptotics of the QML estimators are developed by reparameterization, and bias correction for the estimators is proposed. We also consider the 2SLS and GMM estimations when T could be small.     

Misspecification and Expectations Correction in New Keynesian DSGE Models

This paper focuses on the dynamic misspecification that characterizes the class of small‐scale New Keynesian models currently used in monetary and business cycle analysis, and provides a remedy for the typical difficulties these models have in accounting for the rich contemporaneous and dynamic correlation structure of the data. We suggest using a statistical model for the data as a device through which it is possible to adapt the econometric specification of the New Keynesian model such that the risk of omitting important propagation mechanisms is kept under control. A pseudo‐structural form is built from the baseline system of Euler equations by forcing the state vector of the system to have the same dimension as the state vector characterizing the statistical model. The pseudo‐structural form gives rise to a set of cross‐equation restrictions that do not penalize the autocorrelation structure and persistence of the data. Standard estimation and evaluation methods can be used. We provide an empirical illustration based on USA quarterly data and a small‐scale monetary New Keynesian model.     

Decentralized Welfare: Will There Be Underprovision?

This paper develops an Asymmetric Nash Equilibrium model of welfare provision by states when the benefit payment is a local public good and a fixed population of welfare recipients distributes itself between states with logistic “migration” function. The model shows that state size is an important demand shifter across states because it alters the supply elasticity of recipients. The model provides estimates of how the degree of benefit under provision varies with this migration elasticity. Other demand instruments (such as taxpayer resources and “generosity”) likewise generate positive correlation between benefits and recipients, while supply shifters generate negative correlation between benefits and recipients. The model's predictions are closely matched empirically, when examining the reduced form impact of these instruments on the pattern of welfare benefits and recipients across states. Using these impacts to assign the instruments to either supply or demand sides of the model, it is possible to estimate the model's structural elasticities. These turn out to be high enough so that simulated solutions to the model generate considerable welfare underprovision and thus raise concern about a race to the bottom with decentralized control over AFDC.     

Dynamic pairs trading using the stochastic control approach

We propose a model for analyzing dynamic pairs trading strategies using the stochastic control approach. The model is explored in an optimal portfolio setting, where the portfolio consists of a bank account and two co-integrated stocks and the objective is to maximize for a fixed time horizon, the expected terminal utility of wealth. For the exponential utility function, we reduce the problem to a linear parabolic partial differential equation which can be solved in closed form. In particular, we exhibit the optimal positions in the two stocks.     

A note on computing equilibria in economies with activity analysis models of production

Equilibria in economies without production can be approximated by computing fixed points of continuous functions. With production present, the functions are usually replaced by set-valued mappings and fixed-point algorithms converge slowly. Here we propose continuous functions whose fixed points are equilibria in economies whose production is modelled by a finite list of activities. The penalty is that a least-distance program must be solved at each iteraction. The approach generalizes to allow ad valorem taxes on production. Finally, analogous arguments apply to the computation of an invariant optimal vector of capital stocks.     

Delivery lags and buffer stocks in the theory of investment by the firm

This paper contains a dynamic model of a firm holding a stock of unfilled orders for output while facing a fixed delivery lag attached to acquiring new capital goods. The model leads to a two-stage optimal control problem where the initial time interval corresponds to the Marshallian short-run and the second interval is the period during which deliveries of capital goods may arrive. Optimality criteria are provided for both time intervals and the behavior of the firm is characterized along both adjustment paths. The short-run decisions of the firm are shown to be tied to long-run decisions planned by the firm.     

Unintended consequences of child care regulations

The effects of regulations governing staff-child ratio, group size, and staff qualifications in child care centers are estimated, using data on a sample of centers. The data contain measures of staff characteristics and wages, price of the service, and the developmental quality of the child care provided. Regulations vary across states, but may be endogenous to these outcomes. Estimates with state fixed effects are feasible because regulations vary within states by age group of children and job title of staff. Estimates with state fixed effects show that tougher regulations have some impact on input use, but have little or no impact on price and quality. The most striking finding is that tougher regulations reduce staff wages, suggesting that the incidence of child care regulations is on employees of day care centers.     

我国基础工程造价管理研究

近年来,随着国民经济的不断增长,人们生活水平日渐提高,因此,建设工程作为固定资产投资项目的主要部分已经越来越受到人们的重视,随之而来的,建设工程的基础工程造价管理工作的重要性也越来越突出了。本文从我国基础工程造价管理的现状入手,分析了如今基础工程造价中存在的问题。由于在市场经济条件下工程造价的控制与管理是一个动态的过程,因此,为了更好的控制工程建设资金,节约投资,我们要做到有的放矢,加强我国基础工程造价的管理工作。     

Cointegration Vector Estimation by Panel DOLS and Long‐run Money Demand*

We study the panel dynamic ordinary least square (DOLS) estimator of a homogeneous cointegration vector for a balanced panel of N individuals observed over T time periods. Allowable heterogeneity across individuals include individual‐specific time trends, individual‐specific fixed effects and time‐specific effects. The estimator is fully parametric, computationally convenient, and more precise than the single equation estimator. For fixed N as T→∞, the estimator converges to a function of Brownian motions and the Wald statistic for testing a set of s linear constraints has a limiting χ²(s) distribution. The estimator also has a Gaussian sequential limit distribution that is obtained first by letting T→∞ and then letting N→∞. In a series of Monte‐Carlo experiments, we find that the asymptotic distribution theory provides a reasonably close approximation to the exact finite sample distribution. We use panel DOLS to estimate coefficients of the long‐run money demand function from a panel of 19 countries with annual observations that span from 1957 to 1996. The estimated income elasticity is 1.08 (asymptotic s.e. = 0.26) and the estimated interest rate semi‐elasticity is ?0.02 (asymptotic s.e. = 0.01).     

International synchronization of the Mexican states business cycles: Explaining factors

The aim of this paper is to identify the explaining factors of the synchronization of the business cycles of the Mexican states and those of the US economy. The cycle indicator is obtained by de-trending the series of total formal employment (Mexican states) and nonfarm employment and industrial production (US). In general, our panel data model estimations suggest the existence of spatial autocorrelation and significant time-period fixed effects. Also, the estimates indicate a significant and positive effect of the ratio of foreign direct investment to gross domestic product (GDP), which may be supplementing the impact of international trade (driven by the most internationally integrated states) and a negative effect of the ratio of remittances to GDP (driven by less integrated states). Finally, the evidence suggests that more similar productive structures yield more synchronized business cycles.     

军事物流业务流程管控系统初探

为适应军事物流系统的动态变化特点,提高军事物流信息系统的有效集成、快速适应变化的能力,从军事物流业务流程管控入手,以系统角色与元素权限为基点,改变信息系统对业务流程管理的传统固化结构为可定制结构,生成业务流程管控系统的体系结构,实现业务流程、数据流程和数据服务等要素之间的低耦合度,为军事物流信息系统研发提供了可参照的体系结构。     

企业应急决策对不实信息传播控制的定量模型研究

不实信息传播给企业造成巨大影响,企业应急措施可以有效控制事态.针对由产品质量问题引起的企业声誉突发事件,结合不实信息传播特点及经典SIR模型,建立动力学模型研究不实信息传播规律,探讨不同企业应急决策下不实信息传播的最终稳定状态,为企业管理者在应对不实信息传播时提供理论依据和决策支持.