A new generalized Weibull distribution in income economic inequality curves

Researchers have been developing various extensions and modified forms of the Weibull distribution to enhance its capability for modeling and fitting different data sets. In this note, we investigate the potential usefulness of the new modification to the standard Weibull distribution called odd Weibull distribution in income economic inequality studies. Some mathematical and statistical properties of this model are proposed. We obtain explicit expressions for the first incomplete moment, quantile function, Lorenz and Zenga curves and related inequality indices. In addition to the well-known stochastic order based on Lorenz curve, the stochastic order based on Zenga curve is considered. Since the new generalized Weibull distribution seems to be suitable to model wealth, financial, actuarial and especially income distributions, these findings are fundamental in the understanding of how parameter values are related to inequality. Also, the estimation of parameters by maximum likelihood and moment methods is discussed. Finally, this distribution has been fitted to United States and Austrian income data sets and has been found to fit remarkably well in compare with the other widely used income models.     

Does biomass energy consumption reduce total energy CO2 emissions in the US?

This study investigates the causal relationship between total biomass energy consumption, total energy CO₂ emissions, and GDP in the United States for the period January 1973–December 2016 by employing a directed acyclic graph (DAG) techniques and the Autoregressive Distributed Lag (ARDL) model. Additionally, this paper examines the existence of the environmental Kuznets curve (EKC) hypothesis. The result of the DAG reveals that total biomass energy consumption and GDP have a unidirectional contemporaneous causal relationship with total energy CO₂ emissions. Based on the results of the ARDL, we find that a 1% increase in per capita total biomass energy consumption causes a 0.65% reduction in per capita total energy CO₂ emissions in the long-run. This finding implies that expanding the usage of biomass is one way to reduce and control greenhouse gases in the US. Moreover, we find that the inverted U-shaped EKC hypothesis is satisfied for the US case. Findings from this study suggest that energy policies should stimulate an increase of biomass production for reducing total energy CO₂.     

Detecting diagnostic accuracy of two biomarkers through a bivariate log-normal ROC curve

In biomedical research, two or more biomarkers may be available for diagnosis of a particular disease. Selecting one single biomarker which ideally discriminate a diseased group from a healthy group is confront in a diagnostic process. Frequently, most of the people use the accuracy measure, area under the receiver operating characteristic (ROC) curve to choose the best diagnostic marker among the available markers for diagnosis. Some authors have tried to combine the multiple markers by an optimal linear combination to increase the discriminatory power. In this paper, we propose an alternative method that combines two continuous biomarkers by direct bivariate modeling of the ROC curve under log-normality assumption. The proposed method is applied to simulated data set and prostate cancer diagnostic biomarker data set.     

手动爬楼梯轮椅的运动过程分析

对一种手动爬楼梯轮椅的运动过程进行了分析。在各部件不与楼梯台阶相干涉的条件下，计算出了车辆质心位置的座标值，并依此绘出质心的位移轨迹曲线。计算了轮椅在上爬楼梯时运动期的中间段质心的速度、加速度以及人的操纵力值。为进一步进行动力学分析和轮椅的改进设计提供了依据。     

中美国债收益率比较分析——来自2002—2014 年国债市场的经验证据

国债收益率波动对于一国金融市场配置资源的效率,乃至金融市场的稳定具有重要影响。本文以2002-2014年中美国债市场数据为样本,从国债收益率曲线、收益率波动以及影响因素等方面对中美国债收益率进行了比较研究。结果发现,中国交易所市场和银行间市场国债收益率形态并不一致,中美国债收益率波动也具有各自特征;中美国债收益率对于美元指数变化的反应并不相同,当美元升值时,中美国债收益率表现出一定程度的趋同性,而当美元贬值时,中美国债收益率则表现出一定程度的背离;中美国债收益率对于物价指数变动的反应相同,均与各自国内物价指数间呈现正向关系。基于此,论文从丰富国债交易品种、完善交易机制、发挥国债市场资金价格功能等方面提出了完善我国国债市场发展的政策建议。     

基于单位球面生成的等距双NURBS刀具路径规划

目前由离散刀位点数据生成的2条NURBS曲线刀具路径中,刀轴点NURBS曲线与刀具中心点NURBS曲线间 距有可能存在不相等的问题,提出一种单位球面下优化刀轴矢量NURBS曲线的方法,用以解决生成的等距双NURBS刀 具路径中2条NURBS曲线间距有可能不相等的问题。算例表明,本算法可以对工件坐标系下的线性刀路进行光顺,确 保双NURBS样条曲线的间距相等。     

胶辊数字中高机的设计

针对印刷机中普通胶辊由于胶辊扰度造成印制品厚薄不均的问题,以中高度法原理为依据,提出了将中高度曲 线方程解析成以时间为变量的函数,用单片机计算和控制中高机运动,设计了以单片机、交流伺服控制器、变频器和磨头 等构建的一个数字控制系统为核心的胶辊数字中高机。应用结果表明数字中高机可安装在普通车床上实现中高胶辊的 加工,且中高曲线和中高度可任意设置,设计简便实用,便于推广。     

Developmental Patterns in Marital Satisfaction: Another Look at Covenant Marriage

This study investigated differences in the trajectory of marital satisfaction in the first 7 years between couples in covenant versus standard marriages. The authors analyzed data on 707 Louisiana marriages from the Marriage Matters Panel Survey of Newlywed Couples, 1998–2004, using multivariate longitudinal growth modeling. When the sample was restricted to couples who remained married over the duration of the study, a marginal benefit of covenant status was found for husbands. This effect was largely accounted for by covenant husbands' more extensive exposure to premarital counseling. The linear decline in marital satisfaction over time that obtained for both husbands and wives was not, however, any different for covenant marriages versus standard marriages. Couples characterized by more traditional attitudes toward gender roles were significantly less satisfied than others. High premarital risk factors, initial uncertainty about marrying the spouse, and the presence of preschool‐age children in the household were all corrosive of marital satisfaction at any given time.     

New V control chart for the Maxwell distribution

Control charts have been popularly used as a user-friendly yet technically sophisticated tool to monitor whether a process is in statistical control or not. These charts are basically constructed under the normality assumption. But in many practical situations in real life this normality assumption may be violated. One such non-normal situation is to monitor the process variability from a skewed parent distribution where we propose the use of a Maxwell control chart. We introduce a pivotal quantity for the scale parameter of the Maxwell distribution which follows a gamma distribution. Probability limits and L-sigma limits are studied along with performance measure based on average run length and power curve. To avoid the complexity of future calculations for practitioners, factors for constructing control chart for monitoring the Maxwell parameter are given for different sample sizes and for different false alarm rate. We also provide simulated data to illustrate the Maxwell control chart. Finally, a real life example has been given to show the importance of such a control chart.     

Repetitive variable acceptance sampling plan for one-sided specification

In this paper, a variable repetitive group sampling plans based on one-sided process capability indices is proposed to deal with lot sentencing for one-sided specifications. The parameters of the proposed plans are tabulated for some combinations of acceptance quality levels with commonly used producer's risk and consumer's risk. The efficiency of the proposed plan is compared with the Pearn and Wu [Critical acceptance values and sample sizes of a variables sampling plan for very low fraction of defectives. Omega – Int J Manag Sci. 2006;34(1):90–101] plan in terms of sample size and the power curve. One example is given to illustrate the proposed methodology.