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1.
Cathy W. S. Chen Hong Than-Thi Mike K. P. So 《Journal of Statistical Computation and Simulation》2019,89(2):191-210
This paper proposes a new hysteretic vector autoregressive (HVAR) model in which the regime switching may be delayed when the hysteresis variable lies in a hysteresis zone. We integrate an adapted multivariate Student-t distribution from amending the scale mixtures of normal distributions. This HVAR model allows for a higher degree of flexibility in the degrees of freedom for each time series. We use the proposed model to test for a causal relationship between any two target time series. Using posterior odds ratios, we overcome the limitations of the classical approach to multiple testing. Both simulated and real examples herein help illustrate the suggested methods. We apply the proposed HVAR model to investigate the causal relationship between the quarterly growth rates of gross domestic product of United Kingdom and United States. Moreover, we check the pairwise lagged dependence of daily PM2.5 levels in three districts of Taipei. 相似文献
2.
3.
鲜大权 《电子科技大学学报(社会科学版)》2006,(6)
利用李群对称方法,通过构造变换不变量,将一类1 1维非线性波动方程化为常微分方程,得到了这一类非线性波动方程的一些新的显式精确解,包括孤子解、三角函数解和椭圆函数周期解。 相似文献
4.
讨论了非线性时滞微分方程H(t,x(t),x(t—r)+f(t,x(t—τ))—g(x(t—σ))=0的振动性,推广了有关文献的部分结果. 相似文献
5.
Charles W. Griffiths Chris Dockins Nicole Owens Nathalie B. Simon Daniel A. Axelrad 《Risk analysis》2002,22(4):679-688
To quantify the health benefits of environmental policies, economists generally require estimates of the reduced probability of illness or death. For policies that reduce exposure to carcinogenic substances, these estimates traditionally have been obtained through the linear extrapolation of experimental dose-response data to low-exposure scenarios as described in the U.S. Environmental Protection Agency's Guidelines for Carcinogen Risk Assessment (1986). In response to evolving scientific knowledge, EPA proposed revisions to the guidelines in 1996. Under the proposed revisions, dose-response relationships would not be estimated for carcinogens thought to exhibit nonlinear modes of action. Such a change in cancer-risk assessment methods and outputs will likely have serious consequences for how benefit-cost analyses of policies aimed at reducing cancer risks are conducted. Any tendency for reduced quantification of effects in environmental risk assessments, such as those contemplated in the revisions to EPA's cancer-risk assessment guidelines, impedes the ability of economic analysts to respond to increasing calls for benefit-cost analysis. This article examines the implications for benefit-cost analysis of carcinogenic exposures of the proposed changes to the 1986 Guidelines and proposes an approach for bounding dose-response relationships when no biologically based models are available. In spite of the more limited quantitative information provided in a carcinogen risk assessment under the proposed revisions to the guidelines, we argue that reasonable bounds on dose-response relationships can be estimated for low-level exposures to nonlinear carcinogens. This approach yields estimates of reduced illness for use in a benefit-cost analysis while incorporating evidence of nonlinearities in the dose-response relationship. As an illustration, the bounding approach is applied to the case of chloroform exposure. 相似文献
6.
吉林省地区间经济力差距分析 总被引:1,自引:1,他引:0
按照Kuznets倒U字假说,我国实现经济高速增长过程中,由于区域经济增长的不平衡性,导致了地区间经济力差距的扩大。吉林省为了尽可能地缩小地区间经济力的差距,以便促进地区的均衡发展,应该在省内形成以信息和高速公路网络为基础的共同市场。 相似文献
7.
张仕金 《江汉大学学报(人文科学版)》2002,21(3):70-73
规范命题的方阵理论最多是未被证明的假说 ;将“允许”作为权利性规范词 ,把“不可以P”等同于“不允许P”是规范方阵理论的两个误源 ;规范命题复合形式展开的正确与否 ,决定于是否准确把握规范词的含义和命题联结词的逻辑性质 相似文献
8.
特征提取是手写体数字识别研究中的重要问题,有效、稳定的特征是提高识别率和识别精度的关键。该文提出了一种基于分数本征特征和核非线性分类器的手写数字识别方法,首先找到时频平面的一个轴进行分数傅里叶变换,使不同类别样本在这个轴上最大限度地分开,然后用主元分析进行降维,得到比较稳健的低维特征,再将常用分类器用于特征分类,实现对手写数字的识别。对实际数据进行实验,结果表明上述本征特征与核非线性分类器相结合有较高的识别率和训练、分类效率。 相似文献
9.
本文研究平面非线性随圆型方程组的Riemann边值问题:在假设条件A1、A2、A3之下,我们证明了该问题存在唯一的解w(z)∈W1.,(■),1<P<+∞ 相似文献
10.
Annual concentrations of toxic air contaminants are of primary concern from the perspective of chronic human exposure assessment and risk analysis. Despite recent advances in air quality monitoring technology, resource and technical constraints often impose limitations on the availability of a sufficient number of ambient concentration measurements for performing environmental risk analysis. Therefore, sample size limitations, representativeness of data, and uncertainties in the estimated annual mean concentration must be examined before performing quantitative risk analysis. In this paper, we discuss several factors that need to be considered in designing field-sampling programs for toxic air contaminants and in verifying compliance with environmental regulations. Specifically, we examine the behavior of SO2, TSP, and CO data as surrogates for toxic air contaminants and as examples of point source, area source, and line source-dominated pollutants, respectively, from the standpoint of sampling design. We demonstrate the use of bootstrap resampling method and normal theory in estimating the annual mean concentration and its 95% confidence bounds from limited sampling data, and illustrate the application of operating characteristic (OC) curves to determine optimum sample size and other sampling strategies. We also outline a statistical procedure, based on a one-sided t-test, that utilizes the sampled concentration data for evaluating whether a sampling site is compliance with relevant ambient guideline concentrations for toxic air contaminants. 相似文献