R12在水平管内流动沸腾换热实验研究

本文对R12在水平管内流动沸腾换热特性作了实验研究。实验结果表明,管内流动沸腾换热与单相对流换热一样,存在热进口效应,国外早期的实验数据由于未能考虑热进口效应而偏大。实验结果还表明,水平流动沸腾周向不均匀换热主要受流动结构影响;截面平均换热系数则与质量流速、热流密度、质量干度和蒸发压力密切相关。分析实验数据证实,流动沸腾换热是由气泡产生而引起的流动充分发展核态沸腾和双相对流蒸发两部分组成的。本文的实验数据与国外已有的换热关系式能较好吻合。     

一般Gauss－Markov模型下一般可估函数的线性充分性和线性完全性

发展了Ｂａｋｓａｌａｒｙ和Ｄｒｙｇａｓ提出的一般Ｇａｕｓｓ－Ｍａｒｋｏｖ模型中线性充分性、最小充分性和完全性的概念，用Ｒａｏ的最小二乘统一理论，给出了这些概念的刻划定理。     

郭大顺:传承人发现者

郭大顺先生的家在沈阳北陵附近,屋中宽大素雅,客厅的墙上挂着一幅字,“华山玫瑰燕山龙,大青山下与。汾河湾旁罄和鼓,夏商周及晋文公。”诗很短,却概括了从6000年前到2000年前的中国古文明,并寓意了其源头的多元化。字的左下角贴着一张彩色照片,略为陈旧,一位老者,微笑,淡定,有大家之风。一问之下,方知这是中国考古界的泰斗,苏秉琦先生,诗便是他作的。郭大顺,河北张家口人,是苏秉琦先生的关门弟子,北京大学历史系考古专业研究生,自从1968年由学校分配到辽宁省博物馆后“,就一头扎到了这里。”在北方地区从事新石器时代和青铜时代考古。1983年…     

指人名词充当主语的名词性谓语句

名词直接充当谓语是汉语所特有的现象,我们称这种句式为名词性谓语,亦即“ＮＰ１—ＮＰ２。”句式。并非所有的名词性词语都能直接作谓语句,所以,本文着重讨论ＮＰ２所特有的结构、意义类型及其述谓性特征,从而对“ＮＰ１－ＮＰ２”句式作出一定的描写和解释。     

女娲人首蛇身形象的结构分析

本文通过古籍中对女娲记载的分析,确定大约汉代时人们对女娲人首蛇身的形象已经形成相对一致的认识;并从野性的思维角度重新审视半人半兽形象的由来,认为人首蛇身是思维对自然—文化秩序进行调和的产物,并具体结合女娲神话分析了人首蛇身的来源和内涵,以及蛇身在大母神形象中的意义、蛇多样的象征意义对女娲神格的影响。     

东临碣石在绥中——《我从龙河走来》选载

读初中的时候就背诵过魏武帝曹操东临碣石,以观沧海这句脍炙人口的诗篇.那么,碣石究竟在哪里呢?我们到辽河流域采访时终于找到了答案: 碣石就在辽宁省绥中县.     

固定效应部分线性变系数面板模型的快速有效估计

本文将最小二乘支持向量机(LSSVM) 和二次推断函数法(QIF) 相结合，为个体内具有相关结构的固定效应部分线性变系数面板模型提供了一种新的快速估计方法；在一定的正则条件下，论证了参数估计量的渐近正态性和非参数估计量的收敛速度；采用Monte Carlo模拟考察了估计方法在有限样本下的表现并将估计技术应用于现实数据分析。该方法不仅保证了估计的有效性和统计推断力，而且程序运行速度得到较大幅度提升。     

Implementing Monte Carlo tests with p-value buckets

Software packages usually report the results of statistical tests using p-values. Users often interpret these values by comparing them with standard thresholds, for example, 0.1, 1, and 5%, which is sometimes reinforced by a star rating (***, **, and *, respectively). We consider an arbitrary statistical test whose p-value p is not available explicitly, but can be approximated by Monte Carlo samples, for example, by bootstrap or permutation tests. The standard implementation of such tests usually draws a fixed number of samples to approximate p. However, the probability that the exact and the approximated p-value lie on different sides of a threshold (the resampling risk) can be high, particularly for p-values close to a threshold. We present a method to overcome this. We consider a finite set of user-specified intervals that cover [0, 1] and that can be overlapping. We call these p-value buckets. We present algorithms that, with arbitrarily high probability, return a p-value bucket containing p. We prove that for both a bounded resampling risk and a finite runtime, overlapping buckets need to be employed, and that our methods both bound the resampling risk and guarantee a finite runtime for such overlapping buckets. To interpret decisions with overlapping buckets, we propose an extension of the star rating system. We demonstrate that our methods are suitable for use in standard software, including for low p-value thresholds occurring in multiple testing settings, and that they can be computationally more efficient than standard implementations.     

An elastic-net penalized expectile regression with applications

To perform variable selection in expectile regression, we introduce the elastic-net penalty into expectile regression and propose an elastic-net penalized expectile regression (ER-EN) model. We then adopt the semismooth Newton coordinate descent (SNCD) algorithm to solve the proposed ER-EN model in high-dimensional settings. The advantages of ER-EN model are illustrated via extensive Monte Carlo simulations. The numerical results show that the ER-EN model outperforms the elastic-net penalized least squares regression (LSR-EN), the elastic-net penalized Huber regression (HR-EN), the elastic-net penalized quantile regression (QR-EN) and conventional expectile regression (ER) in terms of variable selection and predictive ability, especially for asymmetric distributions. We also apply the ER-EN model to two real-world applications: relative location of CT slices on the axial axis and metabolism of tacrolimus (Tac) drug. Empirical results also demonstrate the superiority of the ER-EN model.