New two-stage sampling designs based on neoteric ranked set sampling

Neoteric ranked set sampling (NRSS) is a recently developed sampling plan, derived from the well-known ranked set sampling (RSS) scheme. It has already been proved that NRSS provides more efficient estimators for population mean and variance compared to RSS and other sampling designs based on ranked sets. In this work, we propose and evaluate the performance of some two-stage sampling designs based on NRSS. Five different sampling schemes are proposed. Through an extensive Monte Carlo simulation study, we verified that all proposed sampling designs outperform RSS, NRSS, and the original double RSS design, producing estimators for the population mean with a lower mean square error. Furthermore, as with NRSS, two-stage NRSS estimators present some bias for asymmetric distributions. We complement the study with a discussion on the relative performance of the proposed estimators. Moreover, an additional simulation based on data of the diameter and height of pine trees is presented.     

Inference and optimal design of multiple constant-stress testing for generalized half-normal distribution under type-II progressive censoring

The generalized half-normal (GHN) distribution and progressive type-II censoring are considered in this article for studying some statistical inferences of constant-stress accelerated life testing. The EM algorithm is considered to calculate the maximum likelihood estimates. Fisher information matrix is formed depending on the missing information law and it is utilized for structuring the asymptomatic confidence intervals. Further, interval estimation is discussed through bootstrap intervals. The Tierney and Kadane method, importance sampling procedure and Metropolis-Hastings algorithm are utilized to compute Bayesian estimates. Furthermore, predictive estimates for censored data and the related prediction intervals are obtained. We consider three optimality criteria to find out the optimal stress level. A real data set is used to illustrate the importance of GHN distribution as an alternative lifetime model for well-known distributions. Finally, a simulation study is provided with discussion.     

半参数空间ZISF的估计、分类与蒙特卡罗模拟

零无效率随机前沿模型（ZISF）包含随机前沿模型和回归模型，两模型各有一定的发生概率，适用于技术无效生产单元和技术有效生产单元同时存在的情形。本文在ZISF的生产函数中引入空间效应和非参函数，并假设回归模型的发生概率为非参函数，构建了半参数空间ZISF。该模型可有效避免忽略空间效应导致的有偏且不一致估计量，也避免了线性模型的拟合不足。本文对非参函数采用B样条逼近，使用极大似然方法和JLMS法分别估计参数和技术效率。蒙特卡罗结果表明：①本文方法的估计精度和分类精度均较高。随着样本容量的增大，精度增加。②忽略空间效应或者非参数效应，估计精度和分类精度降低，文中模型有存在必要性。③忽略发生概率的非参数效应会严重降低估计和分类精度，远大于忽略生产函数的非参数效应的影响。     

A Simple Toxicokinetic Model Exhibiting Complex Dynamics and Nonlinear Exposure Response

Uncertainty in model predictions of exposure response at low exposures is a problem for risk assessment. A particular interest is the internal concentration of an agent in biological systems as a function of external exposure concentrations. Physiologically based pharmacokinetic (PBPK) models permit estimation of internal exposure concentrations in target tissues but most assume that model parameters are either fixed or instantaneously dose-dependent. Taking into account response times for biological regulatory mechanisms introduces new dynamic behaviors that have implications for low-dose exposure response in chronic exposure. A simple one-compartment simulation model is described in which internal concentrations summed over time exhibit significant nonlinearity and nonmonotonicity in relation to external concentrations due to delayed up- or downregulation of a metabolic pathway. These behaviors could be the mechanistic basis for homeostasis and for some apparent hormetic effects.     

基于交叉效率DEA与群体共识的区间乘性语言偏好关系群决策

针对区间乘性语言偏好关系群决策问题，提出了一种基于交叉效率DEA和群体共识的群决策方法。首先，提出乘性语言偏好关系导出函数的定义，并构建产出导向的DEA模型，证明了一致性乘性语言偏好关系的DEA效率得分与排序向量之间存在比例关系。在此基础上，建立基于理想值的交叉效率DEA模型，提出乘性语言偏好关系的通用排序方法。同时，基于群体共识建立目标规划模型来计算各语言偏好关系的权重系数。最后，利用Monte Carlo随机模拟的方法对群体语言偏好空间进行统计分析，得到群决策期望排序向量及其可信度。算例分析表明本文方法能够有效的避免信息损失，具有较强的适用性和较高的可信度。     

Effective elements of care-physical activity initiatives for adults with a low socioeconomic status: A concept mapping study with health promotion experts

In care-physical activity (care-PA) initiatives, primary care and sports are combined to stimulate PA among adults at risk of lifestyle related diseases. Preliminary results from Dutch care-PA initiatives for adults with a low socioeconomic status (SES) indicate a decrease in participants’ body weight and an improved quality of life, however, the elements that make these initiatives successful are yet to be identified. In total, 19 Dutch health promotion experts participated in our concept mapping (CM) of the effective elements of care-PA initiatives for adults with a low SES. The experts identified 111 effective elements of these initiatives, which were grouped into 11 clusters, focusing on: 1) approaching participants within the care-PA initiative, 2) barriers experienced throughout the initiative, 3) long-term implementation, 4) customizing the care-PA initiative to the target population, 5) social support, 6) structure and guidance, 7) the professionals within the care-PA initiative, 8) the accessibility of the care-PA initiative, 9) targeted behaviour and progression, 10) recruitment and administration, and 11) intersectoral collaboration. CM was useful for creating a valuable overview of these effective elements. Our results could be used to improve the development and implementation of future care-PA initiatives for adults with a low SES.     

‘Seeing through their Eyes’: Towards Understanding Risk and Protection Perspectives of Young Bedouin Children in the Unrecognised Villages of the Naqab

This article is based on a participatory, context-informed study that examined perception of ‘risk’ and ‘protection’ among 30 Bedouin children aged four to five. It was conducted in the Bedouin unrecognised villages — Southern Israel and utilised photography, drawings and verbal explanations. The analysis yielded seven themes representing children’s perceptions of risk and protection. It indicated that children facing extreme adversity were aware of numerous risk conditions, including a lack of infrastructure and the fear of losing their homes, thus adversely affecting their well-being. Children’s insights, and suggested modes of protection, as the study findings reveal, are crucial for promoting children’s welfare.     

航线网络中需求无约束估计的非参数选择模型

传统的航空客运需求无约束估计方法仅针对平行直达航班中的顾客需求“溢出”和“再 现”问题，未能考虑航空网络中直达和中转联程航班之间的网络替代效应． 基于顾客偏好排序列表定义了航空网络顾客类型集合，建立了考虑顾客策略行为的网络型非参数离散选择模型．考虑到网络环境下历史预售数据的不完备性，站在线上和线下交易平台的角度，分别建立了非截尾和截尾需求情况下的完备数据对数似然函数． 采用 EM 算法对顾客到达率和概率质量函数进行联合估计，并提出了网络环境下的顾客“初始需求”、“再现需求”和“溢出需求”无约束估计计算方法．通过数值模拟验证了所提方法的可行性和有效性，相较于现有方法能准确反映产品间网络替代效应对顾客选择行为影响，从而更加有效地避免对历史顾客“初始需求”的高估问题．     

基于FLOTRAN的燕尾形导轨气浮平台结构设计

闭式燕尾形导轨是常见的静压气浮导轨结构形式之一,其燕尾角度将直接影响导轨的承载能力,为保证设计的燕尾形导轨能满足工作要求,本文通过建立燕尾夹角在55°~70°范围变化的气膜有限元模型,以承载力和刚度作为主要性能指标,对导轨承载能力进行分析.通过分析发现:导轨垂直方向总承载力随着燕尾夹角θ的增大而增大.研究结果表明燕尾夹角θ=66°时,单边导轨垂直方向的承载力为87.26N,刚度为33.69N/μm,能较好地满足承载和工作要求.     

陆梁油田薄层底水油藏水平井井筒模拟研究

新疆陆梁油田呼图壁河组油藏发育一类特殊的薄层底水型油藏，其特点是油层厚度薄，构造幅度低，底水能量大，利用水平井开采，表现出无水采油期短、含水率上升速度快、产量递减大的特点。针对这些问题，采用水平井数值模拟方法，建立了考虑摩擦压力损失的水平井井筒模型，明确了摩擦压力损失对水平井的压力分布以及水平段产量的影响，在此基础上，分析研究了水平井底水锥进的水脊特征，判断了水平井出水位置，提出了封堵出水井段并结合油藏工程方法确定了水平井合理产液量，从而达到抑制底水快速锥进，减小压力损失，降低含水率上升速度的目的。