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Search Results: 1 - 10 of 61509 matches for " 何健 "
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梁下竖向弹性刚度不同的单排桩协同工作分析

工业建筑 , 1996, DOI: 10.13204/j.gyjz199611008
Abstract: 分析了条形承台梁下具有不同的竖向弹性刚度单排桩的协同工作情况,给出此种情况下的单排桩基承载力计算建议
Measurement System of Internet Dynamics Based on Traffic Engineering
基于流量工程的端到端网性能监测系统

,
计算机科学 , 2001,
Abstract: 1.引言网络技术的迅猛发展,Internet的广泛渗透,作为网络的最终用户希望从ISP(Internet提供商)得到高质量的服务,所以Internet运行性能的研究变得更加重要、更具有挑战性,大型IP网络(特别是Internet主干网)的性能监控变成了一个非常值得研究和重视的问题。目前在国际上有很多组织致力于网络性能监控的项目,例如IETF(Internet Engineer Task Force)IPPM工作组,提出了对于网络性能进行评价的标准,定义大范围网络性能测试的模型,为正确进行网络性能的测量提供高效的测量工具和测量技术RFC2330];CAIDA(Cooperative Association for In-ternet Data Analysis)是专门对Internet流量进行研究和分析的国际组织。CAIDA已经开发出了许多的工具,对于Internet网络流量进行采集、统计和分析,以期达到全球网络基础设施的合理利用,优化网络拓扑结构,提高网络的使用性能等目的;APAN(Asia-Pa-
基于Zigbee技术的顶板离层仪网络研究
,小刚
煤炭工程 , 2014, DOI: 10.11799/ce201406048
Abstract: 针对目前煤矿使用的顶板离层仪类型,以及根据顶板离层的测量原理和实际中工作人员记录顶板离层数据的方式,本文创新性地提出了采用Zigbee技术进行数据的传输;利用分站和每个测量点处的顶板离层仪构成了无线传感网络,通过分站人机交互界面就可对矿井巷道顶板离层的状态进行实时监测,实现了顶板离层监测的自动化和网络化;采用了分段式数字电容传感器,提高了产品整体测量精度,降低了成本。
一类微分系统周期解的存在性

福州大学学报(自然科学版) , 1988,
Abstract: 利用平均值的方法[1],[2],对系统:的周期解的存在范围进行研究
不同氧气湿化液对患者手术后吸氧下呼吸道感染的影响
李平,
第三军医大学学报 , 2014,
Abstract:
《建筑结构设计统一标准》问题专栏(十七)——荷载效应组合最大值的分布

工业建筑 , 1982, DOI: 10.13204/j.gyjz198205011
Abstract: 建筑结构通常承受多种荷载作用。因各种荷载及其效应都是依时间、空间而变化的随机过程,因而它们的效应组合则为一新的随机过程。因结构可靠度与结构的设计基准使用期T密切相关,所以,人们十分关注荷载效应组合随机过程在设计基准使用期[O,T)内的最大值的变化规律,即寻求设计基准使用
Caerin的二维HP折叠结构
2-Dimensional HP Folding Structures of Caerin
 [PDF]

, 严少敏, 吴光
Hans Journal of Computational Biology (HJCB) , 2012, DOI: 10.12677/hjcb.2012.24004
Abstract: 采用标准化氨基酸疏水性指数将7Caerins的氨基酸序列转换为28种疏水性(H)或极性(P)的序列,通过二维疏水性极性(HP)模型分析其全部可能的折叠结构。结果显示Caerins有许多具有相同最小能量的天然形态,这些形态有各种各样对称的折叠结构,而且这些天然形态可以根据标准化的氨基酸疏水性指标进一步从数值上加以区分。这项研究从疏水性极性角度揭示了Caerin折叠结构的多样性,有助于理解蛋白质的折叠过程,并提示通过工程学方法修改抗菌肽的可能途径。
The amino acid sequences of 7 Caerins were converted into 28 hydrophobic (H) or polar (P) sequences according to the normalized amino acid hydrophobicity index, and all of their possible folding structures were analyzed using 2D hydrophobic-polar (HP) model. The results showed that Caerins have many native states with the same mini- mal energy, which consist of various symmetric folding structures, and that the normalized amino acid hydrophobicity index can help furthermore distinguish native states numerically. The study demonstrates the diversity of Caerin folding structures from hydrophobic-polar (HP) angle, which can shed light on understanding folding process of protein and implying possible ways to modify antimicrobial peptides through engineering.
基于频域法的地铁钢弹簧浮置板轨道结构减振特性分析
The Vibration Reduction Characteristics of Steel Spring Floating Slab Track Used in Metro Based on Frequency-Domain Method
 [PDF]

远鹏,, 王开云, 圣小珍
Open Journal of Acoustics and Vibration (OJAV) , 2016, DOI: 10.12677/OJAV.2016.41001
Abstract:
钢弹簧浮置板轨道是地铁中常用的减振轨道结构之一,该种轨道结构利用螺旋钢弹簧把轨道结构与基础分开,使轨道板处于悬浮状态,将轨道板振动隔离。本文建立钢弹簧浮置板轨道板有限元模型与传统地铁无砟轨道有限元模型;在该模型中考虑了隧道以及大地的影响,同时使用粘弹性人工边界条件来模拟大地的无限长特性,在轮轨粗糙度激励下,对比分析了钢弹簧浮置板轨道结构和传统地铁无砟轨道结构的振动特性以及钢弹簧浮置板的减振效果。
Steel spring floating slab track is one of the common tracks of vibration reduction used in metro. The steel spring separates track structure and its foundation, which makes the slab instate of suspension to isolate vibration. In this paper, the finite element model of steel spring floating slab track and the traditional ballastless track of metro is established. In the model, the tunnel and ground are considered, and the visco-elasticartificial boundaries are used to simulate the infinite characteristic of the ground. In the excitation of wheel-rail roughness, the vibration characteristic of steel spring floating lab track is analyzed, and vibration reduction effect of steel spring floating slab track is compared to that of the traditional ballastless track of metro.
高浓度悬沙对长江河口水域初级生产力的影响
文珊,
中国生态农业学报 , 2001,
Abstract: 根据近期观测的数据和有关文献表明,长江径流挟带的悬沙与潮流扰动产生的再悬浮泥沙在长江口形成透明度3m和3m以下的浑浊带,浑浊带悬沙的消光作用强于营养盐释放作用,抑制了长江口门区的初级生产力,使口门区的浮游植物生物量及密度显著低于附近水域。经估算,目前长江口浮游植物对N、P的吸收、同化能力分别为6.64万t/km2·a和9220t/km2·a,仅为光合作用效率较高的其他河口海岸水域如加州海岸的10.5%左右,故认为浑浊带悬沙削弱了河口水域生态系统对径流过剩营养盐的吸收、同化功能,间接增加了口门外水域的营养盐浓度,成为邻近海域赤潮频发的潜在因子。
中国西北地区1470~2008年干湿分异的时空场分解
Analysis on Space-Time Field of Dry/Wet Change Since 1470-2008AD in Northwest China Based on REOF
 [PDF]

, 元庆, 王世金, 庞娟, 辛惠娟,
Climate Change Research Letters (CCRL) , 2016, DOI: 10.12677/CCRL.2016.54028
Abstract:
基于历史文献记录,运用REOF分析方法将西北地区1470~2008 AD干湿序列分解为空间函数和时间函数,用前6个主要空间特征向量描述西北地区干湿变化的空间格局,构建区域干湿指数(RDWI),表征区域干湿变化的程度及差异。研究发现:1) 西北地区降水量分布场大致以105?E为界呈现东湿西干的格局,湿极出现在陕南,而玉树则是旱极。2) 1470~2008年西北地区干旱年份有41年,偏干79年,正常年份有285年,偏湿年份95年,湿润年份39年。极端干旱年份有1484,1528,1586,1640,1759,1877,1878,1928,1900,1915,1929;极端湿润年份有1570,1662,1736,1745,1753,1756,1819,1884,1887,1958,1964。3) RDWI数据序列11点低通滤波表明西北地区1470~2008年干湿年代际波动变化特征极为复杂,主要存在8个干湿变化旋回。其中1481~1497,1527~1531,1583~1588,1628~1642,1713~1722,1874~1879,1915~1931年为连续干旱时段。4) 采用小波与连续功率谱分析发现西北地区1470~2008年间存在着64~90年、32~48和11~22年左右的3类周期变化规律。检测出的64年的周期以及未检测出200年的周期与已有研究不同。
Based on the historical record, the REOF method was used to decompose the dry/wet variation in northwest China from 1470 to 2008 into spatial functions and time functions; the spatial pattern of dry/wet differences was described by the first six major space feature vectors; Regional Dry-Wet Index (RDWI) by the corresponding time weighting coefficient was used to represent the time changes of spatial differences. Several important conclusions were found in this paper. First, distribution of dry/wet variation field in northwest China was the dividing line of 105?E. Southern Shaanxi is the wettest place and Yushu is the driest place in the west of 105?E. Secondly, 41 years were very dry in northwest China from 1470 to 2008, and there were 79 dry years, 285 normal years, 95 wet years, and 39 very wet years. Among them, extreme dry years are in 1484, 1528, 1586, 1640, 1759, 1877, 1878, 1928, 1900, 1915 and 1929; extreme wet years are in 1570, 1662, 1736, 1745, 1753, 1756, 1819, 1884, 1887, 1958 and 1964. Thirdly, after 11-point low-pass filter, RDWI data sequence shows that dry-wet decadal fluctuations’ change characteristic is very complex, and there are eight climate change cycles. 1481-1497, 1527-1531, 1583-1588, 1628-1642, 1713-1722, 1874-1879, 1915-1931 years are the persistent dry periods. Last but not least, wavelet and power spectrum analysis shows that some periodicities existed in the last 500 years, such as the periods of around 64 - 90, 32 - 48 and 11 - 22 years. Among them, the detected 64-year periodicity and the not detected 200-year periodicity are different from the existing research.
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