Was the recent downturn in US real GDP predictable?

This article uses a small set of variables – real GDP, the inflation rate and the short-term interest rate – and a rich set of models – atheoretical (time series) and theoretical (structural), linear and nonlinear, as well as classical and Bayesian models – to consider whether we could have predicted the recent downturn of the US real GDP. Comparing the performance of the models to the benchmark random-walk model by root mean-square errors, the two structural (theoretical) models, especially the nonlinear model, perform well on average across all forecast horizons in our ex post, out-of-sample forecasts, although at specific forecast horizons certain nonlinear atheoretical models perform the best. The nonlinear theoretical model also dominates in our ex ante, out-of-sample forecast of the Great Recession, suggesting that developing forward-looking, microfounded, nonlinear, dynamic stochastic general equilibrium models of the economy may prove crucial in forecasting turning points.     

Tail dependence risk exposure and diversification potential of Islamic and conventional banks

This paper undertakes a rolling window comparative analysis of risks for portfolios consisting of GCC Islamic and conventional bank indices. We draw our empirical results by employing canonical, drawable and regular vine copula models, as well as by implementing a portfolio optimization method with a conditional Value-at-Risk constraint. We find evidence of higher riskiness in the group of Islamic banks relative to the group of conventional banks across each of the financial rolling window scenarios under consideration. Specifically, a greater negative (nonlinear) tail asymmetric dependence is observed in the pairs of Islamic banks’ relationships. The results also show that the optimal portfolio model supports a clear preference towards the group of conventional banks in regard to risk minimization and diversification benefits.     

Did the Proposed Country-of-Origin Law Affect Product Choices? The Case of Salmon

The 2002 Farm Securit and Rural Investment Act mandated that country-of-origin labeling (COOL) be applied to specific food commodities. Using revealed preference data for 1998–2006, a nonlinear AIDS model is used to estimate the demand for uncooked frozen, uncooked fresh, and precooked salmon to assess the impact of the legislation on consumer demand patterns. Findings from a non parametric analysis suggest a possible rotation in the demand curve for fresh salmon that may be linked with the quality signal associated with COOL. However, our findings indicate that COOL had no significant impact on overall consumer demand for the three products. All three were found to be inelastic, with uncooked fresh salmon being slightly more price sensitive than uncooked frozen and precooked salmon. Given the expenditure elasticities, the fresh salmon segment of the industry appear to be more vibrant than the other salmon segments and would likely influence investment decisions in the salmon industry.     

资本集聚与经济增长的非线性研究——基于系统动态GMM估计和门槛回归的经验分析

文章基于改进的C-D生产函数构建动态计量模型,利用中国1992-2011年的30个省市的面板数据及系统GMM估计方法,验证了资本集聚与经济增长间的非线性关系的存在性,并对计量模型进行修正建立了门槛回归模型,进行了门限回归,结果表明:资本集聚与经济增长间存在单一门槛值,而且资本集聚水平与交易成本存在此消彼长的关系。据此结论提出政策建议:我国东部沿海地区部分制造业行业资本集聚过度,应该进行资本流向管理及政策引导,让过剩资本流向周边及西部资本相对短缺的地区;中西部落后地区应该创造有利条件,增强资本集聚的动力,充分利用资本集聚的积极效应加快经济增长;同时应该对各种集聚资本的质量加强考核与监管。     

材料力学课程中杆件内力的教学研究

在材料力学课程教学实践中,为了帮助学生总结和系统化所学知识,从学生需要掌握杆件内力的知识点出发,总结得到快速计算杆件内力以及快速绘制对应的内力图的方法,并且提炼出便捷的助记口诀,在教学中取得了较好的效果。     

A note on spurious nonlinear regression

This paper explores the power of two tests for nonlinearity against spurious nonlinear regression. Results show that while the BDS test is susceptible to spuriousness, an approach introduced by Peña and Rodriguez [Peña, D. and Rodriguez, J., 2005, Detecting nonlinearity in time series by model selection criteria, International Journal of Forecasting 21, 731–748.] is powerful, regardless of sample size.     

人民币汇率非线性特征研究——基于R/S分析法的实证检验

以2005年7月21日~2008年3月12日银行间外汇市场六种货币兑人民币汇率数据为样本,采用R/S分析法对其日收益率序列进行了研究,结果表明:六种货币兑人民币汇率日收益率序列均不服从正态分布,普遍地表现为有偏的随机过程;六种货币兑人民币汇率均具有非线性特征,表现为较强的正状态持久性,其波动存在明显的非周期循环。     

挠性转子高速动平衡技术应用

介绍了挠性转子高速动平衡技术,即影响系数法的平衡原理,应用该技术较好地完成了返修汽轮机转子的高速动平衡试验,使转子运行振动值达到了合格标准以内。表明结合影响系数法进行的汽轮机转子高速动平衡试验,是高效、精确且完全能满足生产运行需求的。     

某露天磷矿爆破振动的影响分析

为确定某露天磷矿露天开采爆破振动的传播规律及对周围村庄民居的安全影响,对该矿不同采场的爆破作业振动进行了测试。对监测数据进行回归分析,找出了该矿爆破振动的传播规律及特征,判断爆破引起的振动不会对周围村庄民居产生不良影响,并就如何降低爆破振动影响提出了一些建议,为矿山今后的爆破作业提供了指导依据。     

解析既有框架结构加固中隔震技术的应用

本文主要分析了既有框架结构加固中隔震技术的特点和重要作用,阐述了既有框架中存在的质量问题。笔者结合自身多年工作经验,提出一些政策和措施,希望能帮助相关施工技术人员提高施工技术水平。