湖北七姊妹山自然保护区发现亚高山泥炭藓湿地

七姊妹山自然保护区位于湖北省恩施土家族苗族自治州宣恩县的东部,地理位置为109°37′~109°51E′,29°39~′30°5′N,是我国中亚热带向北亚热带的过渡地区[1].2005年6月,我们对七姊妹山自然保护区的自然植被进行考察,在椿木营首次发现了较大面积的亚高山泥炭藓湿地.该湿地位于椿木营的天花板地、落儿坪等地,海拔1 800 m~1 950 m,呈大斑块状分布,总面积约300 hm2.我们在天花板地和落儿坪分别设置了两个20 m×20 m的调查样地,按照B raun-B lan-quet[2]的植被调查方法,对样地内的植物种类,每种植物的优势度与多度、物候期进行了统计.从物种…     

晶界萌生裂纹扩展的晶体相场模拟

【目的】研究双晶样品在单轴拉伸应变作用下所发生的纳米微观尺度裂纹扩展运动,观察裂纹扩展特征,揭示位错对裂纹扩展的作用规律。【方法】应用晶体相场(PFC)方法模拟裂纹扩展演化及其位错运动。【结果】在位错没有发射之时,裂纹沿位错对柏氏矢量方向解理扩展,发射位错后裂尖沿顺时针旋转60°继续扩展。【结论】晶界滑移出的位错由于周围应力集中,萌生出微裂纹。在裂纹扩展中,裂纹与位错相互作用,可以有多种形式。     

箭载双臂式电场仪的原理与设计

在介绍双臂式电场仪探测原理的基础上,给出了子午工程探空火箭搭载的双臂式电场仪的具体设计.为了降低探针的不对称和不一致性,采用了铝制球形探针设计,使用石墨涂层以减少表面不均匀性,并采用独特的外形设计来消除支撑臂阴影影响|在信号处理部分,为了能提高系统动态范围,采用了分频段处理的方法.最后,结合整体系统设计的需要提出了几点误差考虑,并给出了系统性能测试结果.所设计的电场仪带宽0～5 MHz,直流探测范围为0.1 mV/m～±1 V/m,交流探测范围为10 μV/m～50 mV/m,可以实现对电场强度为0～±1 V/m的空间电场进行二维测量.     

论非战争军事行动中的安全工作

随着国家安全观的内涵不断延伸和非传统安全威胁不断上升,我军遂行非战争军事行动任务日益频繁,面临的情况日趋复杂,影响和危害部队安全稳定的因素逐渐增多。因此,我军应高度重视非战争军事行动中的安全工作,并从加强政治工作、注重预测分析、完善应急管理机制、提升官兵针对性训练水平、进行装备革新等方面着手,把安全工作做细做实,保证在顺利完成任务的同时保持部队安全稳定。     

A comparison of the Medieval Warm Period, Little Ice Age and 20th century warming simulated by the FGOALS climate system model

To compare differences among the Medieval Warm Period (MWP), Little Ice Age (LIA), and 20th century global warming (20CW), six sets of transient and equilibrium simulations were generated using the climate system model FGOALS_gl. This model was developed by the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences. The results indicate that MWP warming is evident on a global scale, except for at mid-latitudes of the North Pacific. However, the magnitude of the warming is weaker than that in the 20th century. The warming in the high latitudes of the Northern Hemisphere is stronger than that in the Southern Hemisphere. The LIA cooling is also evident on a global scale, with a strong cooling over the high Eurasian continent, while the cooling center is over the Arctic domain. Both the MWP and the 20CW experiments exhibit the strongest warming anomalies in the middle troposphere around 200?C300 hPa, but the cooling center of the LIA experiment is seen in the polar surface of the Northern Hemisphere. A comparison of model simulation against the reconstruction indicates that model??s performance in simulating the surface air temperature changes during the warm periods is better than that during the cold periods. The consistencies between model and reconstruction in lower latitudes are better than those in high latitudes. Comparison of the inter-annual variability mode of East Asian summer monsoon (EASM) rainfall during the MWP, LIA and 20CW reveals a similar rainfall anomalies pattern. However, the time spectra of the principal component during the three typical periods of the last millennium are different, and the quasi-biannual oscillation is more evident during the two warm periods. At a centennial time scale, the external mode of the EASM variability driven by the changes of effective solar radiation is determined by the changes of large scale land-sea thermal contrast. The rainfall anomalies over the east of 110°E exhibit a meridional homogeneous change pattern, which is different from the meridional out-of-phase change of rainfall anomalies associated with the internal mode.     

一个具有四翼吸引子的超混沌系统设计与实现

为提高超混沌吸引子的拓扑结构的复杂性,构造了一个新的超混沌系统,对新的系统进行了理论分析和计算机仿真,并设计了一个模拟电路对系统进行实验,实验所得相图与数值仿真一致,是具有四翼吸引子的超混沌系统,从而证明了理论分析和数值仿真的正确性。     

一种利用神经网络改善判断矩阵一致性的方法

针对层次分析法中判断矩阵致性改进问题,提出了一种利用神经网络改善判断矩阵一致性的方法.本文在建立了BP神经网络模型的基础上,把判断矩阵一致性调整问题转化为BP神经网络的多输入多输出求解问题.经BP神经网络算法调整过的判断矩阵再返回给专家进一步调整使其符合萨迪标度.计算实例表明,此种方法是可行的.     

固相萃取-超高效液相色谱法测定烟用水基胶中丙烯酰胺

建立了采用固相萃取-超高液相色谱/紫外检测测定烟用水基胶中丙烯酰胺的分析方法。样品经超纯水进行超声提取,固相萃取柱进行富集净化后,经HSS T3色谱柱分离,以甲醇和水为流动相等度洗脱,紫外检测,外标法定量。结果显示,丙烯酰胺在浓度0.01~20.0μg·mL-1范围内有良好的线性关系,相关系数为0.9999。丙烯酰胺三个不同浓度的加标回收率为91.7%~105.1%;相对标准偏差为1.3%~4.7%(n=6);检出限为3.5μg·L-1。该方法分析时间短、结果准确可靠,满足烟用水基胶中丙烯酰胺的测定。     

行星齿轮变速箱计算机辅助分析

行星变速箱的分析归结为解线性方程组问题。本文介绍如何根据传动方案简图计算机自动建立运动学和动力学矩阵方程 ,对行星变速箱进行运动学和动力学分析。     

基于工业基础类标准的参数化实体模型数据交互技术

针对已有技术参数化程度低、信息易丢失的缺陷,提出了基于工业基础类(IFC)标准的参数化实体模型数据交互技术.确立了实体模型IFC格式文件的基本框架,研究了实体模型各类信息的参数化IFC格式数据表达方法,并通过软件编程实现.结果表明,该参数化实体模型数据交互技术可准确描述复杂实体模型,生成的IFC格式文件可在各主流BIM...