An example of Bayesian inference in thermal sciences

This article explains the method of Bayesian inference in the estimation of parameters. An account of how Bayesian inference can beadapted in a simple case of parameter retrieval in thermal sciences is explained.     

基于虚功误差估计算子服役结构状态评估的统计分析

针对服役结构状态评估问题提出了基于虚功误差估计算子的统计分析方法.首先定义虚功误差来表达实际结构与参数化分析模型之间的差别,然后采用改进的牛顿算法推导分析模型结构识别算法.为了探讨在有测量误差的情况下算法的性能,引用Monte Carlo方法模拟测量数据,对测量数据的误差与识别结果的影响进行了详细的分析比较.根据识别结果确定它的概率分布,通过假设试验对服役结构状态评估进行统计分析.最后应用双跨五层刚架结构进行了大量数值模拟,计算结果显示了所提方法的有效性.     

基于非参数贝叶斯推断的MPSK信号调制识别(英文)

依据星座图采用非参数贝叶斯方法对多元相移键控(MPSK)信号进行调制识别.将未知信噪比(SNR)水平的MPSK信号看成复平面内多个未知均值和方差的高斯分布依照一定的比例混合而成,利用非参数贝叶斯推断方法进行密度估计,实现对MPSK信号分类目的.推断过程中,引入Dirichlet过程作为混合比例因子的先验分布,结合正态逆Wishart(NIW)分布作为均值和方差的先验分布,根据接收信号,利用Gibbs采样的MCMC(Monte Carlo Markov chain)随机采样算法,不断调整混合比例因子、均值和方差.通过多次迭代,得到对调制信号的密度估计.仿真表明,在SNR>5 dB,码元数目大于1 600时,2/4/8PSK的识别率超过了95%.     

混合整数线性模型中方差因子Bayes估计实证分析

采用卫星在不同的历元时所得到的实际载波相位测量数据,得出载波相位在混合整数线性模型中的方差因子的Bayes估计结果,并根据其结果的大小,说明Bayes估计方法的可行性。     

用于交通事故分析的基于贝叶斯方法的条件自回归负二项模型(英文)

为了改进用于分析大量影响因素的交通事故模型,采用基于马尔可夫链蒙特卡罗法和吉布斯抽样的条件自回归负二项模型来拟合过度散布性(由负二项过程拟合)、未观察异质性和空间相关性(由条件自回归过程拟合).统计检验显示,由于具有更小的预测误差和更强的参数估计,条件自回归负二项模型优于条件自回归泊松模型、负二项模型、零膨胀泊松模型和零膨胀负二项模型.研究结果表明,交通事故率和死亡人数与车道数、曲线长度、车道年平均日交通量和降雨量成正比.最大限速和最近医院距离与交通事故次数成反比,而与死亡事故次数成正比,这可能是由于过高的速度会引发更严重的事故以及救援伤者时丧失较长时间.     

An assessment model for proof comprehension in undergraduate mathematics

Although proof comprehension is fundamental in advanced undergraduate mathematics courses, there has been limited research on what it means to understand a mathematical proof at this level and how such understanding can be assessed. In this paper, we address these issues by presenting a multidimensional model for assessing proof comprehension in undergraduate mathematics. Building on Yang and Lin’s (Educational Studies in Mathematics 67:59–76, 2008) model of reading comprehension of proofs in high school geometry, we contend that in undergraduate mathematics a proof is not only understood in terms of the meaning, logical status, and logical chaining of its statements but also in terms of the proof’s high-level ideas, its main components or modules, the methods it employs, and how it relates to specific examples. We illustrate how each of these types of understanding can be assessed in the context of a proof in number theory.     

An input-output model for the assessment of labor skill requirements

The purpose of this essay is to suggest an analytical framework for estimating manpower requirements by skill categories for the purpose of educational planning. In what follows, we first summarise the classic manpower requirements approach and modify it, through the use of an inter-industry model, in order to take into account second order effects in the generation of the demand for skills. Next, the model is applied to actual data to illustrate the techniques used. Although planning applies to future actions, the model is applied within a known period in the past to permit a more realistic testing of its performance and sensitivity. Special attention is given to the question of the relative sensitivity of results to the technical coefficients of a Leontief inter-sectoral input-output matrix and the intrasectoral occupation coefficients, with the distinctive aspects of substitution and productivity change that these structures reflect.     

网络计算环境中服务匹配的贝叶斯均衡应用模型

通过应用不完全信息的贝叶斯博弈理论,为服务匹配双方建立了一个双向拍卖的博弈模型.该模型基于双方各自的QoS期望值进行竞拍,用双方都能取得最大收益的均衡QoS值达成交易,以确保各自的QoS需求和服务匹配成功.相关的讨论和分析表明该模型方法是有效的.     

An assessment model and methods for evaluating distance education programmes

This paper is adapted from a keynote address given to the AUA Annual Conference, held at Warwick 14–16 March 2005     

回溯推理独立存在的合理性问题探微

回溯推理是一种独立于演绎、归纳的推理类型,但有学者对此提出非难。回溯推理独立存在的合理性,在国内外学术界关于该推理的几种典型模式中,从哲学、逻辑学、心理学的不同视角提供了理论支持证据。科学发现、医疗诊断和刑事侦察等在实践上提供了经验支持证据。     

一个不等式成立的充分条件

利用Hahn-Banach定理，给出了在线性赋泛空间中，当M包含X,x0∈X／M,f∈X,f（M）=0时，不等式｜f（x0）｜≤‖f‖ρ（x0,M）成立的一个充分条件。     

Successfully using HPT internationally: An international performance model

This article introduces a new international model that focuses on culture while including familiar elements of human performance technology (HPT). HPT adaptation for cultural differences is an essential part of our profession. We must be sensitive and flexible to succeed in an ever‐changing global environment.     

An assessment of ESL writing placement assessment

What are the best assessment practices for ESL and international students who must be placed into first-year composition courses at both two- and four-year institutions in the United States? In this article, I examine this issue in three ways. First, I enumerate the stances in the literature; following that I submit results of preliminary research which questions modes of writing assessment and their relationship to final grades in composition classes. Finally, I present results of an internet search of one set of prominent American institutions’ placement practices. From this data, it might be inferred that we use multiple instruments to place ESL students into composition classes rather than resorting to a multiple-choice test (especially a standardized instrument) as the sole means of determining placement.My primary purposes in this paper are to argue that second language composition specialists need to examine our placement practices and aim for a reconciliation of these practices with our classroom pedagogies. Further, if we are not involved in placement decisions at our various institutions, we must strive to be included in important decisions concerning our students and to be advocates for second language writers.     

Mechanisms and assessment of water eutrophication

Water eutrophication has become a worldwide environmental problem in recent years, and understanding the mechanisms of water eutrophication will help for prevention and remediation of water eutrophication. In this paper, recent ad- vances in current status and major mechanisms of water eutrophication, assessment and evaluation criteria, and the influencing factors were reviewed. Water eutrophication in lakes, reservoirs, estuaries and rivers is widespread all over the world and the severity is increasing, especially in the developing countries like China. The assessment of water eutrophication has been ad-vanced from simple individual parameters like total phosphorus, total nitrogen, etc., to comprehensive indexes like total nutrient status index. The major influencing factors on water eutrophication include nutrient enrichment, hydrodynamics, environmental factors such as temperature, salinity, carbon dioxide, element balance, etc., and microbial and biodiversity. The occurrence of water eutrophication is actually a complex function of all the possible influencing factors. The mechanisms of algal blooming are not fully understood and need to be further investigated.     

冷凝管内冷却水流动方向的解析

1 问题的提出 在室温下,有些反应速率很小或难于进行.为了使反应顺利地进行,常常需要使反应物质较长时间保持沸腾.这种情况就需要使用回流冷凝装置,使蒸气不断地在冷凝管内冷凝而返回反应器中,以防止反应瓶中的物质逃逸损失[1].     

一种基于Q-学习的智能操作票推理方法

针对电网操作票系统智能性较差、知识库建立困难的问题,提出了一种基于Q-学习算法的智能推理方法,并通过断路器刀闸组和设备刀闸组的概念进行电力系统网络结构建模,系统在多次迭代学习过程中不断更新和改进策略,最终推理出符合电力要求的操作票。测试结果表明,所提方法能够快速地推理出正确的倒闸操作顺序,提高系统的灵活性和通用性。     

Identifying determinants of teachers' judgment (in)accuracy regarding students' school-related motivations using a Bayesian cross-classified multi-level model

Teachers differ considerably in their judgment accuracy of motivational student characteristics. Thus far, only few investigations have focused on explaining these differences. In this study, we investigated to what extent groups of characteristics (i.e., student, information, teacher, and class characteristics) derived from the Realistic Accuracy Model (Funder, 1995) are relevant for explaining differences in teachers' judgment accuracy regarding students' school-related self-concept and autonomous motivation. Data from 1239 students and 341 teachers were analyzed using a Bayesian cross-classified multi-level modeling approach. Our analyses showed that variance in teacher judgments is largely due to variation at the level of judgments and less due to variation in the slope (i.e., the accuracy of teacher judgments). Teachers' judgment accuracy varied to a comparable degree across teachers and classes. Significant determinants for these differences were teachers' subject and students' grade point average.