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41.
根据岩芯孔喉基本计算公式,计算岩芯的平均孔喉直径,通过吸水膨胀后不同大小聚合物微球在岩芯中的封 堵效果,研究了聚合物微球大小与岩芯孔喉的匹配关系,确定了聚合物微球在岩芯中具有稳定封堵性能时微球粒径与 岩芯孔喉直径的比值范围。从聚合物微球吸水膨胀性能、剪切前后微球粒径变化、不同大小聚合物微球在岩芯中的封 堵效果、与岩芯匹配后的聚合物微球调剖作用对水驱采收率的影响几个方面,研究了聚合物微球大小与岩芯孔喉的匹 配关系,从而为聚合物微球调剖体系大小选择提供实验依据。研究表明,当聚合物微球粒径与岩芯孔喉直径比值在 0.33~1.50 时,聚合物微球可以在岩芯中形成稳定的封堵能力,当聚合物微球粒径与孔喉直径比值在1.20~1.50 时,聚 合物微球兼具良好的运移能力和封堵效果。  相似文献   
42.
The paper develops some objective priors for correlation coefficient of the bivariate normal distribution. The criterion used is the asymptotic matching of coverage probabilities of Bayesian credible intervals with the corresponding frequentist coverage probabilities. The paper uses various matching criteria, namely, quantile matching, highest posterior density matching, and matching via inversion of test statistics. Each matching criterion leads to a different prior for the parameter of interest. We evaluate their performance by comparing credible intervals through simulation studies. In addition, inference through several likelihood-based methods have been discussed.  相似文献   
43.
We discuss higher-order adjustments for a quasi-profile likelihood for a scalar parameter of interest, in order to alleviate some of the problems inherent to the presence of nuisance parameters, such as bias and inconsistency. Indeed, quasi-profile score functions for the parameter of interest have bias of order O(1)O(1), and such bias can lead to poor inference on the parameter of interest. The higher-order adjustments are obtained so that the adjusted quasi-profile score estimating function is unbiased and its variance is the negative expected derivative matrix of the adjusted profile estimating equation. The modified quasi-profile likelihood is then obtained as the integral of the adjusted profile estimating function. We discuss two methods for the computation of the modified quasi-profile likelihoods: a bootstrap simulation method and a first-order asymptotic expression, which can be simplified under an orthogonality assumption. Examples in the context of generalized linear models and of robust inference are provided, showing that the use of a modified quasi-profile likelihood ratio statistic may lead to coverage probabilities more accurate than those pertaining to first-order Wald-type confidence intervals.  相似文献   
44.
In this study, adjustment of profile likelihood function of parameter of interest in presence of many nuisance parameters is investigated for survival regression models. Our objective is to extend the Barndorff–Nielsen’s technique to Weibull regression models for estimation of shape parameter in presence of many nuisance and regression parameters. We conducted Monte-Carlo simulation studies and a real data analysis, all of which demonstrate and suggest that the modified profile likelihood estimators outperform the profile likelihood estimators in terms of three comparison criterion: mean squared errors, bias and standard errors.  相似文献   
45.
In most of the existing specialized literature, monitoring regression models are a special case of profile monitoring. However, not every regression model always represents appropriately a profile data structure. This is clearly the case of the Weibull regression model (WRM) with common shape parameter γ. Even though it might be thought that existing methodologies (especially likelihood-ratio (LRT)-based methods) for monitoring generalized linear profiles can also be successfully applied to monitoring regression models with time-to-event response, it will be shown in this paper that those methodologies work fairly acceptable just for data structures with 1000 observations at least approximately. It was found out that some corrections, often referred to as Bartlett's adjustments, are needed to be implemented in order to improve the accuracy of using the asymptotic distributional properties of the LRT statistic for carrying out the monitoring of WRM with relatively small and moderate dimensions of the available datasets. Simulation studies suggest that the use of the aforementioned corrections make the resulting charts work quite acceptable when available data structures contain 30 observations at least. Detection abilities of the proposed schemes improve as dataset dimension increases.  相似文献   
46.
Objective: This study examined the inconsistent relationship found between personal growth initiative (PGI) and posttraumatic stress symptoms (PTSS) by exploring potential subgroups. In addition, after identifying the subgroups, potential predictors of these subgroups were examined. Participants: Participants were 534 undergraduate students who experienced a potentially traumatic event (PTE). Data collection occurred from March 2013 to December 2014. Methods: Because this was a preliminary study, archival data was used. Participants consisted of students who experienced a PTE within the past three years. Results: Latent profile analysis indicated a five-class model as the best-fitting model. Direct exposure and intentionality of the event were significant predictors of class membership; length of time since event and gender did not predict class membership. Conclusions: The current study provides a potential explanation of the inconsistent results between PGI and PTSS and also highlights the importance of acknowledging subgroups when utilizing PGI after a PTE.  相似文献   
47.
The Australian Bureau of Agricultural & Resource Economics (ABARE) has conducted the annual Australian Agricultural and Grazing Industries Survey, covering the broadacre sector, in a consistent format since 1978/79. In this period the incomes of farmers have fluctuated considerably. Interest has focused on temporal income variation because of its relationship to the inherent riskiness of farming. Part of these income fluctuations can be explained by changing commodity prices and by highly variable climatic conditions. This paper outlines a method of measuring the magnitude of this income variation and how it relates to other variables. Due to rotation within the sample of farms surveyed, data are limited for determining the income variability of any particular farm. This paper, using spatial locations of surveyed farms, shows how kernel smoothing techniques can be adapted to estimate the distribution of a farm's income. This analysis uses data collected from 1978/79 to 1991/92. Summary information from these distributions is cross-tabulated against several other variables. This shows that income variability is strongly related to the production mixture of farming businesses.  相似文献   
48.
文章对B公司的营销模式和营销审计应用做了深入研究,并应用竞争态势矩阵(competitive profile matrix,CPM)、同业比较等分析方法对B公司的贵阳分公司进行诊断式营销审计,深刻剖析贵阳分公司业绩差的原因,并提出相应的对策建议,以提升贵阳分公司的业绩.  相似文献   
49.
基于中美30家医院官网英文简介的文本分析,对比中美医院英文简介在传播内容、文本结构、修辞手段和多模态使用等四个方面的异同,讨论中国医院英文简介存在的不足,旨在探讨编译策略在医院简介翻译中的应用。认为医院简介的英译不可采取一一对应的完全翻译策略,而是应充分考虑读者的接受度,通过精简篇幅、筛选内容、厘清结构、变换人称以及增加模态等编译策略使译文无论是在内容层面还是结构形式上都更易为读者所接受,以期达到理想的传播效果。  相似文献   
50.
This study maps the demographic profiles of 4,480 clients of ten problem gambling services in Hong Kong. It attempts to identify help-seekers' characteristics associated with gender, adolescent onset of gambling, and suicidal thoughts/attempts. This aggregation of data to form a gambler service user profile among Hong Kong Chinese is the first of its kind. Service and research implications are discussed.  相似文献   
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