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Search Results: 1 - 10 of 48419 matches for " 谢磊 "
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GC-MS法测定银杏内酯B(原料药)中石油醚残留量
,慧明
安徽大学学报(自然科学版) , 2012,
Abstract:
物联网中基于rfid的移动标签定位方案
郭平?,
计算机科学 , 2015,
Abstract: 当前基于rfid的定位系统无法使用异构移动阅读器按照分布式策略定位移动标签,且定位精度低下。针对这种情况,提出了lsmt-rfid系统。该系统使用一组异构移动式rfid阅读器来定位移动rfid标签,移动阅读器通过时间约束交错过程展开合作,附近的阅读器通过共享询问信息来相应地估计标签位置,并使用主动和被动协议来确保位置信息的及时传输。基于ns-3的仿真实验来评估方案的定位能力,重点考察了平均定位误差和定位延时。实验结果表明,本方案能实现有效定位。
基于卫星遥感的全球洋面降水暖云与非降水暖云的云参数差异
,刘奇
- , 2017, DOI: 10.3969/j.issn.0253-2778.2017.12.006
Abstract: 利用中分辨成像光谱仪(Aqua/MODIS)和云廓线雷达(CloudSat/CPR)两部星载仪器的准同步探测资料,分析了全球洋面暖云覆盖量和暖云降水频率的空间分布特征.并就暖云占优的多个中低纬海域,对降水暖云和非降水暖云的云微物理性质进行了对比,特别分析了由MODIS云滴有效半径(R16,R21,R37)相对大小所指示的云层顶部云水垂直结构在两类云之间的差异.研究结果表明,降水暖云与非降水暖云的云顶温度、光学厚度、云滴有效半径、云水路径等参数的有效范围接近一致,但均值存在明显差异.降水暖云的云顶高度显著偏高,其光学厚度、云滴有效半径、云水路径显著大于非降水暖云.针对6种云水垂直结构模态的初步统计结果显示,对应最大降水概率的模态为R37
Abstract:Data collected from quasi-synchronous Aqua/MODIS and CloudSat/CPR measurements were used to compare cloud parameters between precipitating and non-precipitating warm clouds over global oceans. The characteristics of cloud water vertical structure near cloud top, which were implied by the contrasts among the three cloud droplet effective radii (R16, R21, R37) retrieved from distinct near-infrared channels of MODIS, were especially examined and their discrepancies between the two cloud categories were clarified. It is found that the global distribution of warm clouds has notable regional features. The valid range of most cloud properties are similar for precipitating and non-precipitating warm clouds, including cloud top temperature (CTT), optical thickness (COT), geometrical thickness, cloud droplet effective radius (Re), cloud water path (CWP). But there is still evident distinction between their averages, with the COT, Re, CWP of precipitating warm clouds significantly higher than non-precipitating ones. According to the statistics, the model of R37
空间核反应堆电源闭式Brayton循环热力学分析
Thermodynamic analysis of closed Brayton cycles for space reactor power system

,
- , 2018, DOI: 10.16511/j.cnki.qhdxxb.2018.22.035
Abstract: 空间核反应堆电源闭式Brayton循环一般采用氦-氙混合气体作为循环工质和反应堆冷却剂,设计者为选择合适的循环工质,需研究氦-氙混合气体配比成分变化对循环效率的影响。该文建立空间核反应堆电源闭式Brayton循环热力学模型,采用Fortran 95编程对其进行热力学分析,从绝热系数、回热器回热度、相对压损系数的变化分析了氦-氙混合气体摩尔质量变化对循环效率的影响。结果表明:绝热系数对循环效率的影响较小;回热器回热度越大,循环效率越高;相对压损系数越大,循环效率越低。由于氦-氙混合气体摩尔质量的增加,会降低空间Brayton循环压气机和透平级数,因此选择使回热器回热度达到最大时的配比成分He-8.6% Xe作为循环工质,在给定循环冷/热端温度为403 K/1 300 K的条件下,可以获得29.18%的循环效率。
Abstract:Helium-xenon mixtures can be used as the cycle working fluid and reactor coolant for space nuclear reactor power (SNRP) systems using a closed Brayton cycle. The cycle designers must know how the components of the helium-xenon mixture affect the net system efficiency to choose the best working fluid. A thermodynamic model is developed with Fortran 95 for the SNRP Brayton cycle to analyze the net system efficiency for various molecular mass mixtures in terms of the adiabatic coefficient, regenerator effectiveness and normalized pressure loss coefficient. The results show that the adiabatic coefficient has little effect on the net system efficiency, while the net system efficiency increases with increasing regenerator effectiveness and decreases with increasing normalized pressure loss coefficient. The compressor and turbine in a space Brayton cycle are smaller with higher molecular mass helium-xenon mixtures, so He-8.6%Xe is chosen as the cycle working fluid with the maximum regenerator effectiveness. For cold and hot sink temperatures of 403 K and 1 300 K, the net system efficiency is 29.18%.
阿勒泰东部地区暴雨过程的成因分析
Analysis of the Cause of Heavy Rain in the Eastern Part of Aletai
 [PDF]

张林梅, 秀琴,
Climate Change Research Letters (CCRL) , 2016, DOI: 10.12677/CCRL.2016.54032
Abstract:
利用常规气象观测资料、2015年6月29日阿勒泰地区降水资料以及EC模式细网格和T639模式细网格预报产品,对2015年6月29日阿勒泰东部地区暴雨天气过程的成因进行了天气学分析并检验了暴雨过程的数值模式预报的性能,结果表明:这次暴雨过程100 hPa上南亚高压呈双体型,500 hPa上欧洲长波脊是主导系统,而暴雨的主要影响天气系统是西西伯利亚长波槽,高低空环流形势和影响天气系统合理配置,尤其是中尺度系统活动是暴雨形成的主要原因。阿勒泰东部地区上空深厚的不稳定能量、较强的动力抬升作用、充沛的水汽条件和有利的迎风波地形效应是暴雨产生的缘由。在此次暴雨过程中,各家数值预报产品对于此次天气过程的高度场预报性能较好,与实况相差不大;但对东部暴雨动力条件、水汽条件的预报偏差较大,无参考价值;EC细网格对东部暴雨的雨量预报较接近实况。
Based on the conventional meteorological data, EC model and T639 model of fine grid forecast products, we analyzed the cause of the rainstorm weather process in the east of Aletai on June 29, 2015, and analyzed the performance of the numerical model prediction of the rainstorm process. The results showed that the rainfall process on the South Asian high was 100 hPa double size; 500 hPa Europe long wave ridge was the dominant system; the main influence of rainstorm weather system was West Siberia wave trough, the level of air circulation and weather system reasonably; and especially the mesoscale system activity was the main cause of torrential rain. Over the eastern part of Aletai, the deep unstable energy, strong dynamic uplift, abundant water vapor conditions and favorable terrain effect were the causes of heavy rain. In the course of the storm, the performance of various numerical forecast products to predict height field for the weather was good, similar to the actual situation; but for the heavy rain in eastern dynamic conditions and water vapor condition, prediction showed a large deviation, which had no reference value; while EC fine grid rainfall forecast on the eastern rainstorm was closer to the truth.
碱性A型花岗岩中的富钍锆石: 矿物学研究
,王汝成
科学通报 , 2005,
Abstract: 浙江桃花岛、青田和山东崂山A型花岗岩是中国东部沿海三个典型的燕山期碱性A型花岗岩体.利用电子探针对这些花岗岩中锆石的内部结构和矿物成分进行了分析,结果显示大部分所观察到的锆石颗粒都由两部分组成.一部分显著富钍,ThO2含量大于1%,最高达10.1%,超过了前人实验获得的锆石中钍的溶解极限值(ThO2=5.5%±2.5%),且ThO2/UO2>2,而另一部分则贫钍,ThO2含量小于1%,但该区域以包含微米级钍石包裹体为特征,并常伴有微小的孔洞.同时进行的初步对比研究发现,铝质A型花岗岩中的锆石ThO2含量一般小于1%,ThO2/UO2<2,并且不含任何钍石包裹体.锆石成因矿物学特征表明,富钍锆石可以看作为碱性A型花岗岩的标志性副矿物之一.锆石的富钍性源于其原始岩浆,预示其深源特点.因此,碱性A型花岗岩中高度富钍锆石形成于深源、高温、富钍岩浆的早期结晶阶段;岩浆分异至晚期出现流体相富集,富钍锆石受到流体作用发生溶解重结晶作用,导致低钍锆石和钍石包裹体共生现象.
递归核PCA及其在非线性过程自适应监控中的应用
,王树青
化工学报 , 2007,
Abstract: PCA、PLS作为常用的多变量统计监控算法,一般适用于线性、定常的过程。针对实际工业过程的时变、非线性特性,提出了一种递归核PCA(RKPCA)方法用于非线性过程的自适应监控。RKPCA算法通过将递归奇异值分解推广到核空间,给出了核形式描述的递归KPCA算法,运算复杂度比KPCA明显降低,保证非线性监控模型能够在线更新。在Alstom工业燃气发生装置上的自适应监控表明,所提出的RKPCA算法能够及时跟踪非线性过程的时变特征,保证了监控模型的有效性。
采场围岩应力壳力学特征的岩性效应
广祥,
煤炭学报 , 2013,
Abstract: 应用计算机数值模拟结合现场实测,对软岩、中硬岩和硬岩采场围岩应力壳力学特征的岩性效应进行了分析和研究。研究表明:岩性变化对应力壳力学特征有显著影响,随岩性增强,应力壳高度降低,且由拱形壳向扁平壳转变;壳体内最大应力峰值和高应力集中范围逐渐增大并向工作面上隅角近场围岩和煤柱逼近,冲击性失稳的动力灾害危险性增大。岩性不同,工作面围岩的主要承载力系亦不同,软岩工作面最主要承载力系是围岩应力壳;中硬岩工作面,上覆岩层荷载由围岩应力壳和基本顶承载岩层共同承担;硬岩工作面,围岩应力壳与基本顶承载岩层重合在一起。随岩性增强,工作面围岩破坏场、位移场的分布范围和强度均减小。因此,根据工作面围岩固有的力学属性采取相应的措施,通过改善采场围岩应力分布,对缓和矿压显现实现安全开采有积极作用。
采场围岩应力壳力学特征的工作面长度效应
广祥,
煤炭学报 , 2008,
Abstract: 应用计算机数值模拟并结合现场观测,对不同工作面长度的采场围岩力学特征进行系统的分析和研究,获得了采场围岩宏观应力壳力学特征的工作面长度效应.研究表明,工作面长度的变化对应力壳力学特征有显著影响.随工作面长度的加大,应力壳壳体应力在工作面前方煤壁边缘和巷道附近区域集中程度加大,壳体高度逐渐升高同时扁平率逐渐增大,工作面是三维应力壳的聚焦点;采场围岩的垂直位移变小,而水平位移增大.表明合理调整工作面长度可改善采场围岩宏观应力壳的动态平衡,对保护采场、减小矿山压力显现有积极作用.
综放工作面煤层及围岩破坏特征的采厚效应
广祥,
煤炭学报 , 2010,
Abstract: 综合采用数值模拟、相似材料模拟和现场实测的方法,着重研究采厚变化对综放工作面煤层及围岩破坏特征影响规律。研究表明:工作面煤层及顶煤的破坏范围与采厚成非线性正比,即煤层和顶煤的破坏范围随着采厚的增大而增加;工作面前端煤层破坏最为发育,同一采厚顶煤中的破坏范围明显大于工作面内煤层的破坏范围;采空区煤柱侧巷道破坏区明显大于工作面实体煤侧巷道,且留设的窄小煤柱临近工作面全部进入破坏状态,因此综放工作面回采巷道稳定性应从控制变形角度重点加强采空区煤柱侧的巷道支护。
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