3D打印在Pro/E软件教学中的应用研究

针对当前Pro/E软件教学中的问题,提出将3D打印技术引入课程教学,以增强教学效果。给出了3D打印与Pro/E软件教学相结合的过程,并给出产品建模及3D打印教学的实例。实施结果表明,将3D打印技术引入到Pro/E课程,能提高学生学习兴趣,使学生掌握从产品设计建模到手板制作所需的各项技能。     

Does inflation targeting lower inflation and spur growth?

Over the last few decades several countries have turned to inflation targeting as a policy choice for instilling stability into their economies. Prior studies have shown that inflation targeting has reduced inflation in those countries without significantly impacting GDP. This study seeks to improve upon these results by identifying the impact of timing on the policy decision as well as its impact as related to specific regions of the world. The focus is on developing countries across six regions. We find significant regional variation in developing countries in our sample in terms of the direction of changes in inflation following a switch to the inflation targeting policy. Moreover, although the impact of inflation targeting on real GDP is minimal overall, there is a statistically significant increase in real GDP among developing countries in certain regions only, namely, Europe, Latin America, and the Middle East.     

Half a century of empirical evidence of business cycles in OECD countries

This paper presents evidence regarding the existence of common business cycles in OECD countries. More specifically, the paper examines the extent to which these cycles relate to each other over time. Business cycle components of output are extracted by adopting the Hodrick–Prescott, Baxter–King and the Christiano–Fitzgerald filters. The degree of business cycle co-movements is determined by evaluating the cross-correlation of the cyclical components of output in selected countries. We also implement the bound-testing approach proposed by Pesaran, Shin and Smith (2001) to investigate the long-run and short-run relations among the business cycle components of output. The study covers the period from 1960 to 2010. The empirical results suggest that there are two distinct cycles in the OECD countries: the Euro-area cycle, which includes the business cycles of Germany, France, Italy, Netherlands, Austria and Belgium, and the world cycle, which consists of the business cycles of the United States, Canada and the United Kingdom.     

On the performance of L2E estimation in modelling heterogeneous count responses with extreme values

In healthcare studies, count data sets measured with covariates often exhibit heterogeneity and contain extreme values. To analyse such count data sets, we use a finite mixture of regression model framework and investigate a robust estimation approach, called the L₂E [D.W. Scott, On fitting and adapting of density estimates, Comput. Sci. Stat. 30 (1998), pp. 124–133], to estimate the parameters. The L₂E is based on an integrated L₂ distance between parametric conditional and true conditional mass functions. In addition to studying the theoretical properties of the L₂E estimator, we compare the performance of L₂E with the maximum likelihood (ML) estimator and a minimum Hellinger distance (MHD) estimator via Monte Carlo simulations for correctly specified and gross-error contaminated mixture of Poisson regression models. These show that the L₂E is a viable robust alternative to the ML and MHD estimators. More importantly, we use the L₂E to perform a comprehensive analysis of a Western Australia hospital inpatient obstetrical length of stay (LOS) (in days) data that contains extreme values. It is shown that the L₂E provides a two-component Poisson mixture regression fit to the LOS data which is better than those based on the ML and MHD estimators. The L₂E fit identifies admission type as a significant covariate that profiles the predominant subpopulation of normal-stayers as planned patients and the small subpopulation of long-stayers as emergency patients.     

Smoothed empirical likelihood confidence intervals for the relative distribution with left‐truncated and right‐censored data

The study of differences among groups is an interesting statistical topic in many applied fields. It is very common in this context to have data that are subject to mechanisms of loss of information, such as censoring and truncation. In the setting of a two‐sample problem with data subject to left truncation and right censoring, we develop an empirical likelihood method to do inference for the relative distribution. We obtain a nonparametric generalization of Wilks' theorem and construct nonparametric pointwise confidence intervals for the relative distribution. Finally, we analyse the coverage probability and length of these confidence intervals through a simulation study and illustrate their use with a real data set on gastric cancer. The Canadian Journal of Statistics 38: 453–473; 2010 © 2010 Statistical Society of Canada     

A bivariate distribution with Lomax and geometric margins

We develop a stochastic model describing the joint distribution of $(X,N)$, where $N$ has a geometric distribution while $X$ is the sum of $N$ dependent, heavy-tail Pareto components. Models of this form arise in many applications, ranging from hydro-climatology to finance and insurance. We present fundamental properties of this vector, including marginal and conditional distributions, moments, representations, and parameter estimation. We also include an example from finance, illustrating modeling potential of this new bivariate distribution.     

The sovereign crisis and Italy’s potential output

We evaluate the effects of the European sovereign crisis on Italian potential output (natural output, in the absence of nominal rigidities) by simulating a New Keynesian model. Our results are as follows. First, the 2011–2013 recession subtracted 1.6 percentage points from potential output growth and widened the output gap. Second, the 2013 reforms limited the reduction in output capacity to 1.4 points and enhanced long-run growth by 3. Third, once a balanced budget is achieved in the medium term, reductions in either labor or capital income taxes would boost potential output growth by 0.2 points per year.     

The trinity of wage setting in EMU: A policy proposal

Diverging labor cost developments are often considered to be one of the most important factors that led to large current account imbalances in the euro area (EA) in the run-up to the global financial crisis. It has also been shown that wage growth differentials have significantly lowered the co-movement of EA countries’ business cycles – the most widely used meta-criterion for optimum currency areas. Against this background, this paper develops a wage-setting benchmark that aims to keep the economy in internal equilibrium and to maintain price stability, while it also exhibits the capacity to correct for external imbalances. The proposed wage benchmark is very simple and may serve as an anchor for the macroeconomic dialogue in Economic and Monetary Union. In order to demonstrate the potentially beneficial effects of such a wage benchmark we present some simulations showing how current account balances and labor costs would have developed across EA countries if the rule had served as a benchmark already in the run up to the crisis.     

Credibility and Inflation Expectations: What we can tell from seven emerging economies?

This study is a contribution to the literature concerning credibility and its effect on the distribution between forward-looking behavior and backward-looking behavior for formation of inflation expectations in the case of emerging economies. Based on data gathered from seven inflation targeting emerging economies (Brazil, Chile, Colombia, Mexico, Poland, South Africa, and Turkey), this paper analyzes how much the credibility associated with the inflation target contributes to anchoring expectations. The findings denote that although credibility is relevant to reduce inflation expectations, these countries present low monetary credibility and thus the backward-looking behavior is predominant for the formation of inflation expectations. Therefore, in order to improve the expectations channel of monetary policy in emerging economies, a policy of increasing transparency regarding inflation expectations is mandatory to the central banks’ task of anchoring inflation expectations.     

Periods and structural breaks in US economic history 1959-2007

Principal component analysis (PCA) is applied to six macroeconomic time series observed over 1959-2007. Six periods in US economic history are identified by a cluster analysis of observations in the PCA score plot. The method is data driven with no a priori information on the number or dates of breaks. Our findings give independent support to the effect of the oil price shock in 1973, and the introduction of the Great Moderation period. Of the five transition periods, two have been identified by previous studies as breaks (1973, 1984), one is a well-known date of monetary policy change (1979), and two had not previously been identified (1970, 1977-1978). In the long-run inflation and the federal funds rate are unrelated to industrial production and unemployment. Inflation and interest are positively associated as predicted by the Fisher hypothesis. These long-run relations argue against the use of monetary policy to peg the rate of unemployment or real interest rates. In the short-run inflation acts a leading indicator for unemployment for the period 1959-1997, but not for the period after 1997. The well-established reduction in macroeconomic volatility in the mid-1980s is specific to the period from 1985 to 1997; volatility subsequently rises above pre-1979 levels.