Consistency for the LS estimator in the linear EV regression model with replicate observations

In this paper, we consider the following linear errors-in-variables regression model: ${\xi }_{ij}=x_i+{\delta }_{ij},{\eta }_{ij}=y_i+{\epsilon }_{ij}=\theta +\beta x_i+{\epsilon }_{ij}$, with independent identically distributed errors $({\epsilon }_{ij},{\delta }_{ij}),(j=1,2,\dots ,n_i;i=1,2,\dots )$. The strong and weak consistency for the LS estimators $\stackrel{?}{\beta }$ and $\stackrel{?}{\theta }$ of the unknown parameters $\beta ,\theta$ in this model are obtained, which weaken some known conditions and improve some known results.     

On the Preliminary Test Backfitting and Speckman Estimators in Partially Linear Models and Numerical Comparisons

Przystalski and Krajewski (2007 Przystalski , M. , Krajewski , P. ( 2007 ). Constrained estimators of treatment parameters in semiparametric models . Statist. Probab. Lett. 77 : 914 – 919 .[Crossref], [Web of Science ®] , [Google Scholar]) proposed the restricted backfitting (RBCF) estimator and restricted Speckman (RSPC) estimator for the treatment effects in a partially linear model when some additional exact linear restrictions are assumed to hold. In this article, we introduce the preliminary test backfitting (PTBCF) estimator and preliminary test Speckman (PTSPC) estimator when the validity of the restrictions is suspected. Performances of the proposed estimators are examined with respect to the mean squared error (MSE) criterion. In addition, numerical behaviors of the proposed estimators are illustrated and compared via a Monte Carlo simulation study.     

Estimation of Main Effect When Covariates Have Non-Proportional Hazards

The Cox proportional hazards (PH) regression model has been widely used to analyze survival data in clinical trials and observational studies. In addition to estimating the main treatment or exposure group effect, it is common to adjust for additional covariates using the Cox model. It is well known that violation of the PH assumption can lead to estimates that are biased and difficult to interpret, and model checking has become a routine procedure. However, such checking might focus on the primary group comparisons, and the assumption can still be violated when adjusting for many of the potential covariates. We study the effect of violation of the PH assumption of the covariates on the estimation of the main group effect in the Cox model. The results are summarized in terms of the bias and the coverage properties of the confidence intervals. Overall in randomized clinical trials, the bias caused by misspecifying the PH assumption on the covariates is no more than 15% in absolute value regardless of sample size. In observational studies where the covariates are likely correlated with the group variable, however, the bias can be very severe. The coverage properties largely depend on sample size, as expected, as bias becomes dominating with increasing sample size. These findings should serve as cautionary notes when adjusting for potential confounders in observational studies, as the violation of PH assumption on the confounders can lead to erroneous results.     

Likelihood Ratio Order of m-Spacings in Multiple-Outlier Models

This article deals with the multiple-outlier exponential model. The likelihood ratio order between m-spacings of the combined sample is developed, some results extend the conclusions on simple spacings in Wen et al. (2007 Wen , S. , Lu , Q. , Hu , T. ( 2007 ). Likelihood ratio order of spacings of heterogeneous exponential random variables . J. Multivariate Anal. 98 : 743 – 756 .[Crossref], [Web of Science ®] , [Google Scholar]).     

数字经济对我国市域农业经济韧性的影响效应与机理分析——基于系统GMM模型与动态门槛模型的检验

基于2011—2019年我国277个市域农业的面板数据,运用反事实方法科学测度了其经济韧性水平,并借助系统GMM模型、中介模型和动态门槛模型等方法,实证检验了数字经济对市域农业经济韧性的影响效应及作用机理。研究发现：数字经济显著增强了市域农业经济韧性,这一结论经一系列稳健性检验后仍能成立;机制分析结果表明,农业资本深化是数字经济提升市域农业经济韧性的重要路径。异质性分析表明,在东部、中部、西部地区和人力资本水平较高的地区,数字经济对市域农业经济韧性的影响效应更为显著,而对东北部地区的提升效应则不显著。动态门槛检验进一步揭示,数字经济对市域农业经济韧性的影响呈现边际递增的非线性特征,当数字经济发展水平越过特定门槛值（0147）时,数字经济对市域农业经济韧性的促进作用显著增强。     

京津冀城市圈公共服务供给水平测度及其区域差异分析

京津冀公共服务一体化是突破京津冀发展瓶颈,推动京津冀区域协同发展的重要抓手之一。本文以京津冀城市圈13个城市为研究区域,通过构建公共服务供给水平的评价指标体系,利用熵值法测度了2014-2017年京津冀城市圈各城市的公共服务供给水平,并对其呈现出的区域格局及区域差异进行探讨,结果显示:京津冀城市圈不同城市间公共服务供给水平差异显著,呈现出以北京和天津为中心逐渐衰减的空间格局;2014-2017年京津冀城市圈不同城市间公共服务供给水平的区域差异逐渐缩小,公共服务供给水平由不均衡格局逐渐向均衡格局演进。本文研究结果为推进京津冀城市圈公共服务协调发展提供建议参考。     

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。     

吕氏集团对汉初岭南政策的两次调整

关于吕氏集团执政期间汉朝与南越国的矛盾冲突,传统研究多集中于吕后及其称制时期,而忽视了对事件整体性的把握,即未从吕氏集团执政的全过程加以审视。事实上,吕氏集团对南越国的政策存在两次重要调整,一是吕后时期从怀柔转向对抗,二是"诸吕"时期从南征转为罢兵。吕氏集团的第一次调整只是对原有政策的过激推行,第二次调整则可能是缓和双方关系的一种尝试。但前者不顾客观现实而冒险行事,后者缺乏后续措施而加剧了危机。因此,虽然吕氏集团的两次政策调整均出于巩固政权的需要,但其冒进与盲动的行为只能导致汉朝南部藩属体系陷入空前的危机之中。     

致密碳酸盐岩气藏转向酸酸压技术研究

在分析大牛地气田低渗致密碳酸盐岩储层地质特征的基础上，针对储层改造现状和改造难点提出了转向酸酸压技术。从理论和实验两方面分析了转向酸体系的转向机理，通过流变性能、酸岩反应动力学、转向性能及破胶性能实验分析了转向酸体系的综合性能，最后在A 井试验应用了转向酸酸压工艺，取得了大牛地气田碳酸盐岩储层勘探开发的突破。