Seasonal variation of snow microbial community structure in the East Rongbuk glacier, Mt. Everest

Mt. Everest, the zenith of the world, plays an impor- tant role in the global climate change. During the lastdecade, some studies on glacier and snow have been undertaken in this region. The climate and environment changes in the past hundred years have b…     

Strategy for the mapping of interactive genes using bulked segregant analysis method and Mapmaker/Exp software

A qualitative trait is usually controlled by a single gene, but it may be sometimes controlled by two or even more genes. This phenomenon is called gene interaction. Rapidly searching for linked mo- lecular markers via bulked segregant analysis (BSA) and then constructing regional linkage map with Mapmaker/Exp has become a common approach to mapping single major genes. However, methods and computer programs developed for mapping single major genes cannot be simply applied to interactive genes because the genetic patterns of gene interac- tions are quite different from that of single-gene in- heritance. Up to now, experimental methods for quickly screening molecular markers linked to inter- active genes and statistical methods and corre- sponding computer softwares for simultaneously analyzing the linkage relationships of multiple mo- lecular markers to an interactive gene have not been available. To solve this problem, in this paper, we propose a strategy for mapping interactive genes using BSA and Mapmaker/Exp. We demonstrate that all interactive genes can be mapped by the 'BSA Mapmaker/Exp' strategy using F2 generation (in a few cases, F3 generation is also needed). As BSA and Mapmaker/Exp have been broadly used in gene mapping studies and are well known by many re- searchers, the strategies proposed in this paper will be useful for practical researches.     

Experimental studies on interaction of water mist with class K fires

Interaction of water mist with cooking oil fires is studied experimentally and theoretically. A LDV/APV system is used to measure the velocity and diameter of water mist at different pressures in the experiments,and the effect of water mist velocity and diameter on fire extinguishment efficiency is investi-gated. The experimental results show that water mist has excellent surface cooling effect; it can control and extinguish cooking oil fires quickly without re-ignition. The critical temperature (Tfo) is calculated by energy balance equation,and the fire plume momentum is calculated and compared with that of water mist in order to determine the critical velocity (νwy) of fire extinguishment. This paper provides references for cooking oil fires extinguishment with water mist.     

Linux系统基于PIC中断实现的分析

在专业的教学中,一般对中断处理的原理都较为熟悉,但常常对中断具体的实现感到困惑。事实上,早期在计算机中引入中断技术是为了实现CPU与I/O设备的并行工作以提高CPU的效率,随后又应用于随机的、复杂事务的处理。PIC(可编程中断控制器)是现代微机中通用的中断控制器。本文通过对Linux2.0.x版本的内核源代码的分析,详细描述了Linux系统对中断的具体处理过程,同时也阐述了Linux的内核机制。     

凹甲陆龟的泌尿生殖系统

凹甲陆龟的肾扁平，左右肾形状大小不一，呈荷兰豆荚形或块状方形．有特殊折叠，折起的形成可能与消化系统发达、遗传发育等因素有关．泄殖腔内有明显的环褶将肛道与尿、生殖道分开．附睾长而大，可能与精子的发育成熟和繁殖习性有关．     

电迁移型阻锈剂

迁移型阻锈剂及其实施技术是修补盐污染钢筋混凝土结构的一种新材料和新技术.它在不影响结构正常运行的条件下,从盐污染的混凝土表面透过混凝土保护层迁移到钢筋表面,使其再钝化,从而有可能经济、简便并有利于环保地实现钢筋界面的电化学修补.实验表明:所研制的醇胺类迁移型阻锈剂(BE)对于14mm厚混凝土内的活化钢筋具有显著的阻锈效果;对于盐污染轻的44 mm厚混凝土内的活化钢筋也具有阻锈作用(约优于国外一种专利产品),但均难以足够浓度自然迁移到保护层厚40mm的钢筋上.以盐污染混凝土结构电化学脱盐所采用的电流密度,进行了BE的电迁移试验,表明BE能迅速电迁移厚达10cm的混凝土内,富集到钢筋上,并可显著阻锈.初步优化了电迁移制度(电化学脱盐期有可能从30 d,缩短为5～7 d).在连云港近海的大浦东抽水站盐污染腐蚀破坏的三跨横梁现场,试用BE电迁移技术,历时3年,仍具有良好的阻锈效果.     

一个具有半连续Gteaux导数的泛函的minimax定理和非线性波方程的解(英文)

本文中,我们证明了一个minimax定理,利用这个定理,我们证明了一个新的非线性波动方程的边界值问题的解的存在唯一性定理．     

一种新型含氧燃料对柴油机燃烧特性的影响

为解决柴油机的碳烟颗粒和氮氧化物排放难以同步降低的矛盾,在一台TY1100直喷柴油机上对新设计的一种含氧添加剂乙酸-2-甲氧基乙酯(MEA)和柴油的混合燃料进行了燃烧和排放的试验研究.结果表明:MEA可与柴油实现良好的互溶;在相同的工况下,随着混合燃料中MEA比例的增加,柴油机缸内的最高压力变化较小,但滞燃期略有延长,瞬时放热率增加,燃烧持续时间变短;MEA可以显著降低柴油机的碳烟排放,可使HC和CO的排放有一定程度的降低,但对发动机NOx的排放没有明显的影响;在不改变发动机结构参数的条件下,当燃用体积分数为15%的MEA混合燃料时,发动机的碳烟排放平均降低约50%,发动机的标定功率下降约5%,而热效率提高约2%.     

基于地磁定轨和扩维卡尔曼滤波的导航算法

为了克服扩展卡尔曼 (Kalman)滤波算法对噪声统计特性的约束 ,针对磁强计量测噪声为有色噪声伴常值干扰的特性 ,提出了一种基于扩维Kalman滤波算法的地磁导航算法 .该算法为了使量测噪声白噪化 ,引入了 2个新的状态变量 ,此时测量噪声是均值为 0的高斯白噪声 ,并满足扩展Kalman滤波算法的约束条件 .对由此构成的系统使用扩展Kalman滤波算法 ,可以得到扩维Kalman定轨导航算法 ,利用该算法可以获得国产磁强计的导航精度 ,其地心距模的估计误差为 2 0km ,速度模的估计误差为 10m/s .卫星的实测数据仿真结果表明 ,该导航算法具有较好的稳定性和收敛性 ,克服了扩展Kalman滤波算法的发散问题     

数字图书馆的元数据检索技术的研究与实现

文章首先介绍了当前数字图书馆的定义．元数据的重要性．结合我们研究所承担的某高校数字图书馆项目的实际情况，详细分析了都柏林核心数据的特点．设计出了数字资源的元数据结构和基于元数据的检索系统。