一种新颖的低功耗、强移动性的密码锁设计

本文介绍一种基于单片机控制的电子密码锁设计。本系统由P89LPC900系列单片机、矩阵键盘和报警系统组成。系统能完成电子控制开锁、超时报警、超次锁定、管理员解密和修改用户密码的基本功能。除上述基本的密码锁功能外,还具有节电模式、掉电存储、按键中断唤醒等功能。该系统结构简洁、成本低、体积小,功能实用。     

Bankruptcy costs, liability dollarization, and vulnerability to sudden stops

Countries with intermediate levels of institutional quality suffer larger output contractions following sudden stops of capital inflows than less developed nations. However, countries with strong institutions seldom experience significant falls in output after capital flow reversals. We reconcile these two observations using a calibrated DSGE model that extends the financial accelerator framework developed in Bernanke, Gertler and Gilchrist (1999). The model captures financial market institutional quality with creditors' ability to recover assets from bankrupt firms. Bankruptcy costs affect vulnerability to sudden stops directly but also indirectly by affecting the degree of liability dollarization. Simulations reveal an inverted U-shaped relationship between bankruptcy costs and the output loss following sudden stops.     

Bounded rationality,expectations, and child labour

This paper develops a model with overlapping generations, where the household's optimal fertility, child labour, and education decisions depend on the parents’ expectations or beliefs about the return to education. It is shown that there exists a range of parental income where the fertility rate is high and children participate in the labour market and receive an incomplete education if a parent believes the return to education is low. The act of participating in the labour market reduces the child's ability to accumulate human capital; thus, the action of sending a child into the labour market is sufficient to ensure that the parents’ initially pessimistic expectations are fulfilled. It is then shown that a one‐time policy intervention, such as banning child labour and mandatory education, can be enough to move a country from the positive child labour equilibrium to an equilibrium with no child labour.     

A uniqueness proof for monetary steady state

The framework in Lagos and Wright (2005) [20] combining decentralized and centralized markets is used extensively in monetary economics. Much is known about that model, but there is a loose end: only under special assumptions about bargaining power or decentralized market preferences has it been shown that the monetary steady state is unique. For general decentralized market utility and bargaining, I prove uniqueness for generic parameters with fiat money, and for all parameters with commodity money. As a corollary, I get monotone comparative statics.     

On indeterminacy and growth under progressive taxation and productive government spending

We examine the theoretical interrelations between equilibrium (in)determinacy and economic growth in a one‐sector representative‐agent model of endogenous growth with progressive taxation of income and productive flow of public spending. We analytically show that, if the demand‐side effect of government purchases is weaker, the economy exhibits an indeterminate balanced‐growth equilibrium and belief‐driven growth fluctuations when the tax schedule is sufficiently progressive or regressive. If the supply‐side effect of public expenditures is weaker, indeterminacy and sunspots arise under progressive income taxation. In sharp contrast to traditional Keynesian‐type stabilization policies, our analysis finds that raising the tax progressivity may destabilize an endogenously growing economy with fluctuations driven by agents’ self‐fulfilling expectations.     

Optimal contracts and the role of the government in wage bargaining

This paper introduces a contract between the government and trade unions in a model of strategic wage bargaining à la Lippi (2003). It shows that an optimal contract can be implemented through an appropriately defined inflation target.     

Wages,selectivity, and vacancies: Evaluating the short-term and long-term impact of the minimum wage on unemployment

Using a circular matching model (Marimon R, Zilibotti F. Unemployment vs. mismatch of talents: Reconsidering unemployment benefits. Economic Journal 1999;109; 266–291), where the wage setting is similar to Weiss (Weiss A. Job queues and layoffs in labor markets with flexible wages. Journal of Political Economy 1980; 88; 526–538), we reexamine Card and Krueger's (Card, D., Krueger, A. Myth and Measurement, the New Economics of the Minimum Wage. Princeton University Press; 1995) intuition on the impact of the minimum wage on unemployment. In the short term, a rise in the minimum wage increases the employment level by making firms less selective. In the long term, numerical simulations show that, despite the reduction of job creation, introducing a minimum wage may lower unemployment as soon as workers and jobs are sufficiently differentiated. However, beyond some limit, the wage increase raises unemployment whatever the degree of differentiation is.     

Words that shake traders : The stock market's reaction to central bank communication in real time

This paper investigates the effects of Federal Reserve's decisions and statements on U.S. stock and volatility indices (Dow Jones Industrial Average, NASDAQ 100, S&P 500, and VIX) using a high-frequency event-study analysis. I find that both the surprise component of policy actions and official communication have statistically significant and economically relevant effects on equity indices, with statements having a much greater explanatory power of the reaction of stock prices to monetary policy. For instance, around 90% of the explainable variation in S&P 500 is due to the surprise component of Fed's statements. This paper also shows that equity indices tend to incorporate FOMC monetary surprises within 40 min from the announcement release. Finally, I find that these results are robust along several dimensions. In particular, I consider different estimators, such as the Generalized Empirical Likelihood, and I extend the sample to include the recent period of heightened financial stress. This sensitivity analysis corroborates that central bank communication about its future policy intentions is a key driver of stock returns.     

协同商务环境下B/S结构的物流管理信息系统的研究

论文介绍了协同商务的概念以及协同商务在现代物流中的重要性,分析协同商务环境下的物流管理信息系统的体系结构和功能模块,并对协同商务环境下的物流管理信息系统的有关实现技术进行了探讨。     

Technology Shocks and Monetary Policy: Revisiting the Fed's Performance

Would the U.S. economy's dynamic response to permanent technology shocks have been different from the actual responses if monetary authorities' systematic response to these shocks had been optimal? To answer this question, we characterize the dynamic effects of permanent technology shocks and the way in which U.S. monetary authorities reacted to these shocks over the sample 1955(1)–2002(4) using a structural VAR. A sticky price–sticky wage model is developed and estimated to reproduce these responses. We then formally compare these responses with the outcome of the optimal monetary policy.