ZigBee技术在智能交通信号灯控制中的应用研究

针对传统的定时切换交通信号控制模型已无法满足日益增长的交通需求,采用ZigBee无线传感器网络技术。设计一种智能控制信号灯系统,根据当前道路的实时情况,将采集的实时信息,通过ZigBee网络,发送到子控制模块。由子控制模块传输到主控制模块,主控制模块对数据进行处理,产生合理的交通信号灯动态配时方案,进行较为合理的道路管理,提高交通效率。实验结果证明该系统利用巨磁阻传感器和加速度传感器,结合对道路情况实时采集,通过ZigBee无线网络传送信息;设备之间通过无线网络连接,无需挖路布线,在智能交通领域具有一定的应用价值。     

MIMO-OFDM系统同步技术研究进展

多输入多输出正交频分复用（MIMO-OFDM）系统对定时偏移和频率偏差极其敏感,并且对时间同步精度要求极高。分析比较了29种具有代表性的MIMO-OFDM系统同步算法的优缺点,指出针对数据辅助类的同步方法,采用共轭、取反等特性构造优良正交性的训练序列是提高时间同步性能的关键,可在时域进行频偏估计和降低参数维数来降低系统计算复杂度;针对非数据辅助类的同步方法,构造计算复杂度较低的代价函数是提高频率同步性能的关键,这些都是MIMO-OFDM系统同步方法值得研究的方向。     

Endogenous retailer preferences in intermediate good markets

We model strategic interaction in a differentiated input market as a game among two suppliers and n retailers. Each one of the upstream firms chooses the specification of the input which it will offer.Then, retailers choose their type from a continuum of possibilities. The decisions made in these two first stages affect the degree of compatibility between each retailer's ideal input specification and that of the inputs offered by the two upstream firms. In a third stage, upstream firms compete setting input prices. Equilibrium may be of the two-vendor policy or of the technological monopoly type.     

Endogenous fertility and growth in a model with old age support

Summary. This paper examines the interrelationship between capital accumulation, fertility, and growth by introducing an endogenous fertility decision into Diamond's (1965) neoclassical growth model. Under the assumptions that children provide old age support and that individuals incur a variable time cost of raising children, it investigates the potential for cyclical fluctuations in the capital-labor ratio and fertility, as well as for development trap phenomena to be observed. It is shown that when capital and labor are highly substitutable in production, there is a unique steady state equilibrium, and either damped or undamped oscillations in fertility and the capital-labor ratio may occur. However, when the elasticity of substitution between capital and labor is less than one, two steady state equilibria may exist; one with a high capital-labor ratio and a high rate of population growth, and the other with a lower capital-labor ratio as well as a lower population growth rate. The former is a saddle, while the latter may be either a source or a sink. In the latter case development traps are possible. Received: June 16, 1997; revised version: December 18, 1997     

所得税申报中资产时间性差异的调整方法比较

在所得税申报中,资产时间性差异的纳税调整要涉及几个纳税年度,并且一个正常生产经营企业的资产往往处在动态过程中。每年有新增资产,也有出售、报废、到期的资产,要准确无误地对其进行纳税调整,是所得税申报中的一个常见问题也是难点问题。文章通过对所得税申报中资产时间性差异调整的两种方法的比较,确定一种较为简便可行的方法。     

Two-step estimation of panel data models with censored endogenous variables and selection bias

This paper presents some two-step estimators for a wide range of parametric panel data models with censored endogenous variables and sample selection bias. Our approach is to derive estimates of the unobserved heterogeneity responsible for the endogeneity/selection bias to include as additional explanatory variables in the primary equation. These are obtained through a decomposition of the reduced form residuals. The panel nature of the data allows adjustment, and testing, for two forms of endogeneity and/or sample selection bias. Furthermore, it incorporates roles for dynamics and state dependence in the reduced form. Finally, we provide an empirical illustration which features our procedure and highlights the ability to test several of the underlying assumptions.     

Trade liberalisation and endogenous growth: A q-theory approach

This paper introduces a new approach to the analysis of endogenous growth effects and uses it to illustrate two novel trade-and-growth links. The approach’s simplicity allows us to introduce scale economies and imperfect competition into the R&D and financial intermediation sectors of a Romer–Grossman–Helpman endogenous growth model. We show that trade liberalisation can stimulate growth via a procompetitive effect in the R&D sector and/or financial sector.     

Health Insurance, Liquidity and Growth

Within the context of an endogenous growth model, it is shown that in the presence of health risks which influence household income, the introduction of a private insurance company increases the long-term economic growth rate. The introduction of such an institution has two effects on savings: a level effect and a composition effect. Although the presence of this risk-reducing institution induces a decrease in the level of total savings, as suggested in earlier papers, the rate of illiquid savings, which contribute to growth, increases.
JEL Classification E 1; G 2; O 1; O 4     

Fertility,intergenerational transfers and economic development

This paper develops a model of endogenous growth where agents are altruistic and value both the utilities of their parent and of their children. Individuals endogenously choose the number of their children, and arbitrate between financing education, leaving them some bequest and offering some gift to their parents. We establish the existence of three types of long run regime. Starting from a low level of human capital, an economy converges towards a stationary state associated with a constant output per worker, a high level of fertility and ascendant transfers. If the initial level of human capital is not too low, another stationary state jointly exists with a lower level of fertility and no transfer. Finally, starting from a high level of human capital, the economy experiences a steady growth of output per worker associated with a low fertility level and descendant transfers. We then assume that an economy is initially in the stationary underdevelopment regime with ascendant transfers, and we study the power of different policies to push the economy toward the growth regime. We successively consider a fertility control policy, an education subsidies policy, and the introduction of a pension system for the elderly.     

When will payoff maximization survive? An indirect evolutionary analysis

Survival of payoff maximization is the usual as if-justification for assuming rational economic agents. An indirect evolutionary analysis allows for stimuli which are not directly related to reproductive success although they affect behavior. One first determines the solution for all possible constellations of stimuli, and then the evolutionarily stable stimuli. Our general analysis confirms the special results of former studies that payoff maximization in case of commonly known stimuli requires either that own success does not depend on other's behavior or that other's behavior is not influenced by own stimuli. When stimuli are private information, one can derive similar necessary conditions.