Simulating random variables using moment-generating functions and the saddlepoint approximation

When we are given only a transform such as the moment-generating function of a distribution, it is rare that we can efficiently simulate random variables. Possible approaches such as the inverse transform using numerical inversion of the transform are computationally very expensive. However, the saddlepoint approximation is known to be exact for the Normal, Gamma, and inverse Gaussian distribution and remarkably accurate for a large number of others. We explore the efficient use of the saddlepoint approximation for simulating distributions and provide three examples of the accuracy of these simulations.     

论“被现代”图景在现代中国文学中的展现

"现代"是由各种向不同方向扯动的诸多主题共同建构的一种历史凝缩的结果。"现代"是背靠启蒙运动和工业革命的社会进程。它的发展将整个世界卷入其中。它同时拥有积极阳光的一面和腐烂阴暗的一面。后者集中体现在那些没有两大背景的"被现代"的第三世界国家。现代中国就是不幸处于现代时空中的第三世界国家。在现代中国文学中,我们能够看到"被现代"所带来的无奈与衰颓。老舍的《骆驼祥子》就是展现这幅"被现代"图景的典型作品之一。     

Curation: a theoretical treatment

Curation is a key mechanism of sociality in a digital era. With an abundance of information, sifting, sorting, selecting, hiding, and standing out become laborious tasks. While researchers have diligently documented people’s curatorial strategies, digital curation remains undertheorized in its own right. I therefore theorize digital curation by disentangling productive curation from consumptive curation, addressing how people curate content that they share, and that which they consume. I embed these agentic curatorial practices within structural bounds, both social and technological. In doing so, I offer a basic theoretical model that captures a dynamic relationship between individual curators, their social networks, and technological design.     

胡尖山地区长 6、长 4+5 储层有利区预测

摘要：以胡尖山油田长 6、长 4+5 油藏为例，综合应用地质资料、岩芯分析资料、测井资料以及试油资料，开展了长 6和长 4+5 油藏小层划分和对比、单井相分析，建立测井相识别模式，编制小层沉积相平面展布图，进而分析沉积相演化规律；探讨储层砂体展布以及物性分布规律，从而深入认识研究区的储层特征。在此基础上对储层进行流动单元的划分，然后结合试油资料对胡尖山油田长 6、长 4+5 油藏的储层进行有利区域的预测，为油田待开发区域的合理建产开发提供了理论指导     

近代城市空间改造的时空进程

近代城市人口的增长、城市职能的变化、市政机构的出现带来了城市空间的转变。２０世纪初，中国开始了大范围的城市基础设施改造与新建。其中最有代表性的是拆城、填濠、修筑环城马路的工程，此后全国大部分的城市改造都遵循了相似的模式。本文通过对近１２００座治所城市城墙变动信息的研究发现，２０世纪大规模的城市空间改造最初主要从东南沿海省份开始，３０年代末至４０年代的战争打破了这一过程，但随着新中国成立后城市建设的恢复，空间改造的进程继续向西部省份推进，总体上呈现由东向西，由中心向边缘发展的特点。     

Finding Bhaskar in all the wrong places? Causation,process, and structure in Bhaskar and Deleuze

This article examines the reception of Roy Bhaskar amongst some contemporary Deleuzians. It proceeds by rejecting the all too often predilection of opposing realism to ‘postmodernism’ or ‘post‐structuralism’ arguing instead for the need to bring one into dialogue with the other. To this end, the paper explores the resonances and points of departure between the work of Gilles Deleuze and Roy Bhaskar. In particular, it examines the language of causation, object‐oriented versus process‐oriented ontologies, as well as the charge by Deleuzians that Bhaskar is an essentialist. Through this engagement it attempts to develop and rethink explanation and causation in terms of a more chaotic ontology of machines, centered around the concept of structure, process, and production in an open, heterogeneous, and dynamic world. The end result is a more chaotic concept of realism.     

Producing information: communication and collaboration in the South African scientific community

Prior research has investigated the relationships between communication, collaboration and production of information/knowledge. Most of this research has been conducted either in developed countries where the internet facility is highly advanced or in developing countries with little internet access. Investigations in countries that fall in between these two extremes are rare. This study of respondents from higher education institutions and research institutes examines the relationship between collaboration and internet use, as well as productivity and internet use in the South African scientific system which has become a strong contributor to science in Africa.     

A Semiparametric Regression Model for Longitudinal Data with Non‐stationary Errors

Motivated by the need to analyze the National Longitudinal Surveys data, we propose a new semiparametric longitudinal mean‐covariance model in which the effects on dependent variable of some explanatory variables are linear and others are non‐linear, while the within‐subject correlations are modelled by a non‐stationary autoregressive error structure. We develop an estimation machinery based on least squares technique by approximating non‐parametric functions via B‐spline expansions and establish the asymptotic normality of parametric estimators as well as the rate of convergence for the non‐parametric estimators. We further advocate a new model selection strategy in the varying‐coefficient model framework, for distinguishing whether a component is significant and subsequently whether it is linear or non‐linear. Besides, the proposed method can also be employed for identifying the true order of lagged terms consistently. Monte Carlo studies are conducted to examine the finite sample performance of our approach, and an application of real data is also illustrated.     

Bayesian Classifiers Applied to the Tennessee Eastman Process

Fault diagnosis includes the main task of classification. Bayesian networks (BNs) present several advantages in the classification task, and previous works have suggested their use as classifiers. Because a classifier is often only one part of a larger decision process, this article proposes, for industrial process diagnosis, the use of a Bayesian method called dynamic Markov blanket classifier that has as its main goal the induction of accurate Bayesian classifiers having dependable probability estimates and revealing actual relationships among the most relevant variables. In addition, a new method, named variable ordering multiple offspring sampling capable of inducing a BN to be used as a classifier, is presented. The performance of these methods is assessed on the data of a benchmark problem known as the Tennessee Eastman process. The obtained results are compared with naive Bayes and tree augmented network classifiers, and confirm that both proposed algorithms can provide good classification accuracies as well as knowledge about relevant variables.     

基于职业工作过程的高职计算机基础课程教学改革实践

当前基于工作过程的课程体系建设已经成为我国高职教育课程发展的重要方向。文章针对计算机基础课程教学中面临的主要问题,结合实际的教学实践,对基于职业工作过程的高职计算机基础课程教学改革进行了探讨。