面向面内刚性环模型的变参数等效路面模型研究

针对重载车辆行驶过程中轮胎受力大、变形大,传统等效路面模型反映轮胎动态特性作用有限的问题,在定参数等效路面模型的基础上建立变参数串联椭圆凸轮模型,考虑轮胎受力情况对椭圆凸轮形状参数的影响。在MATLAB/Simulink中建立基于面内刚性环轮胎模型的1/4车系统仿真模型,分别对路面和椭圆凸轮进行离散化处理,采取循环迭代的方法同时仿真出等效路形与系统动力学特性。仿真结果表明,在低速行驶时两种模型仿真结果一致;在高速行驶条件下利用变参数等效路面模型计算所得等效路形失去对称结构,更加符合真实轮胎越障状况,为精确的面内刚性环轮胎建模提供方法和理论参考。     

合并单元对智能化PMU装置测量结果影响分析

合并单元(merging unit,MU)作为智能化同步相量测量装置(phasor measurement unit, PMU)数据采集的主要物理载体,其性能直接影响到装置测量计算结果的准确性。针对智能化PMU装置测量误差存在超差的问题,构建了用于测试智能化PMU装置测量误差的检测平台,研究合并单元影响智能化PMU装置测量结果的因素,最终确定了对智能化PMU装置测量误差产生关键影响的因素以及各种因素的影响程度,并提出了相应的建议,对指导智能化PMU装置的现场检测工作提供一定的参考。     

Phytolith analysis of Naminan archaeological site in Jinghong City,Yunnan Province

The global climate underwent tremendous changes during the transition from the Last Glacial Period to the Holocene. At almost the same time, human society transitioned from the Paleolithic to the Neolithic. Therefore, the relationship between climate change and human activity during this period has become a research hotspot.Yunnan Province is a region with a great abundance of Paleolithic archaeological sites in China; however, Neolithic sites are relatively few. There has also been relatively little research on paleoclimatic conditions during the Paleolithic-Neolithic transition in Yunnan. Phytoliths, as a highly durable and long-lasting form of plant microfossils, can be an important means for reconstructing paleoclimates. In this study, we examined the Naminan site in Jinghong, which was occupied during the transitional period from the Paleolithic to Neolithic. Based on our analysis of the phytolith record at Naminan, we reconstructed the climatic conditions for each of the archaeological strata and discussed possible human activities. The results show that Naminan experienced a sequence of warming followed by cooling and warming, which is consistent with previous paleoclimate research in other areas of Yunnan Province.     

A Note on the Property of ψ-Function

About the accurate value of ψ ( x ) = Γ′ ( x ) / Γ ( x), we know only ψ (1)and ψ (1/ 2).In this paper, by calculating the accurate values of some series expansion of a function and applying some skills of complex analysis, we prove that the expression of the ψ-function admits a finite expression in elementary function for rational number z. As an application, some examples are given.     

用Barkhausen杂讯研究中碳钢的低周疲劳损伤特性

用磁无损检测技术中的Barkhausen杂讯法评估中碳钢的底周疲劳过程，表明Barkhausen杂讯的幅值B随循环周次N的增长而变化，可以利用B和N的关系曲线来评估材料的损伤特性.     

The stress response factor RpoS is required for the natural transformation of Escherichia coli

The natural transformation of Escherichia coli is a novel and recently developed system that has significance for genetic studies and the biological safety of genetic engineering. However, the mechanisms of transformation, including development of competence and DNA uptake, are not thoroughly understood. In this study, we demonstrated the effect of the general stress response regulator RpoS, which has been associated with E. coli transformation, on natural transformation performed in an “open system”. We find that RpoS is required for natural transformation but not to artificial transformation and RpoS mainly affect transformation in the liquid culture prior to plating. In the liquid culture, RpoS over-expression promotes natural transformation in early exponential phase and static incubation accumulates RpoS and promotes transformation to a limited extent. These findings provide detailed understanding of RpoS function on natural transformation.     

一种基于循环回归的推荐算法

提出了一种基于循环回归的推荐算法.首先,对原数据集中的评分数据及缺失值进行离散化处理,然后对离散化数据进行回归模型训练,此过程循环执行并最终建立推荐系统.在离散化阶段,对比不同的离散方法,并对它们的分类粒度开展研究.在模型训练阶段,讨论回归算法对于模型性能的影响.数值计算实验表明,本算法较之近年非常热门的SVDFeaute方法,能够产生更小的均方根误差,验证了算法的有效性.     

浅谈燃气采暖热水炉的概念及其检验标准

从中国加入世贸组织引起燃气行业标准改革入手，引出燃气采暖热水炉的概念，燃气采暖热水炉标准的编写势在必行，并阐述了燃气采暖热水炉的新旧产品检验标准内容要求的不同之处。     

网上CAI系统技术

本文在总结网上CAI已有成果的基础上，概述了未未网上CAI的特点，并提出了网上CAI系统设计的一些想法，指出了尚待研究的一些问题。