oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 308 )

2018 ( 6970 )

2017 ( 7259 )

2016 ( 7633 )

Custom range...

Search Results: 1 - 10 of 298666 matches for " 刘晓凯 "
All listed articles are free for downloading (OA Articles)
Page 1 /298666
Display every page Item
CFRP加固混凝土短柱轴压性能研究
Performance Study on Axial Compression of CFRP-Strengthened Concrete Columns
 [PDF]

, 王清远, 王志宇
Hans Journal of Civil Engineering (HJCE) , 2015, DOI: 10.12677/HJCE.2015.43014
Abstract:
通过对6个混凝土柱的静力加载试验,本文研究了碳纤维布加固对不同截面混凝土柱的力学性能的影响,分析了碳纤维布粘贴层数及短柱截面类型对碳纤维布加固效果的具体影响。结果表明:碳纤维布可明显提高混凝土柱的刚度和极限承载力,减小柱的竖向位移,减小柱的横向应变和纵向应变;当碳纤维布粘贴层数为两层时,其影响程度比粘贴一层时更为显著,但其提高程度不与加固面积成正比;碳纤维布加固对混凝土圆柱极限承载力和刚度的提高优于对混凝土方柱的提高。
Through the static load test of six CFRP reinforced concrete columns, the paper studies the CFRP reinforced concrete columns with different cross section of the influence of mechanical properties, and analyzes the specific influence of the carbon fiber cloth paste layer and column’s section type to carbon fiber cloth reinforcement effect. The results show that: Carbon fiber cloth can obviously increase the stiffness and ultimate bearing capacity of concrete columns, reduce the vertical dis-placement of column and reduce the lateral strain and the axial strain of the columns. When the paste layer of carbon fiber cloth is two, the impact is more obvious. But the increase degree is not proportional to the reinforced area; the improvement of carbon fiber cloth reinforcement to con-crete columns’ ultimate bearing capacity and stiffness is superior to the improvement of concrete square column.
100名医学生后极部脉络膜厚度的测量与分析
The Measurement and Analysis of Posterior Choroidal Thickness in 100 Medical Students
 [PDF]

红霞, , 王少鹏,,, 马丙芬
Hans Journal of Ophthalmology (HJO) , 2015, DOI: 10.12677/HJO.2015.42004
Abstract:
目的:应用增强深部成像的相关光断层扫描(EDI-OCT)仪测量100名医学生后极部脉络膜的厚度,并分析其与性别、眼轴之间的关系。方法:研究对象为100名医学院大学生,平均年龄23.1 ± 1.1岁。应用EDI-OCT扫描受检者双眼后极部脉络膜,分别测量黄斑中心凹下及距离黄斑中心凹3 mm处的脉络膜厚度。结果:黄斑中心凹处脉络膜厚度(SFCT)平均为202.8 ± 49.0 μm。黄斑中心凹上方3 mm处脉络膜厚度最厚,为235.9 ± 68.4 μm。黄斑中心凹鼻侧3 mm处脉络膜最薄为150.5 ± 55.5 μm。男性与女性脉络膜厚度之间的差别以及左右眼之间的差别无明显统计学意义(P > 0.05)。眼轴长度在23.23 mm到27.88 mm范围内,随眼轴长度每增长1 mm,黄斑鼻侧脉络膜厚度减少17.46 μm。其他四个位置的脉络膜厚度无明显规律可循。结论:100名医学生后极部脉络膜的厚度与性别无关,而黄斑中心凹鼻侧脉络膜厚度随眼轴增长有变薄的趋势。
Objective: To study posterior choroidal thickness in 100 medical students and to determine its cor-relation with sex and axial length. Materials and Methods: Cross-sectional observational study of 197 eyes in 100 medical students (mean age = 23.1 ± 1.1 years). The macular choroid was imaged using enhanced depth imaging spectral-domain optical coherence tomography (EDI-OCT). Subfoveal choroidal thickness (SFCT) and choroidal thickness were measured by visual inspection and manual fitting of the choroidal borderlines, at 3 mm inferior, superior, nasal, and temporal to the fovea, respectively. Results: The mean SFCT was 202.8 ± 49.0 μm. The choroidal thickness was the biggest (235.9 ± 68.4 μm) at 3 mm superior to the fovea, and was the thinnest (150.5 ± 55.5 μm) at 3 mm nasal to the fovea. No significant difference had been found in the choroidal thickness between male and female volunteer (P > 0.05), either between right and left eyes (P > 0.05). Ocular axial length between 23.23 mm to 27.88 mm, foveal nasal lateral choroidal thickness decreased by 17.46 μm per mm along axial length, the difference between the other four sites of the choroidal thickness was without obvious regularity. Conclusions: The posterior choroidal thickness of 100 medical students has nothing to do with sex, while the foveal nasal lateral choroidal thickness get thinner with the axial growth.
基于GPS的无人值守变电站故障设备定位系统研究
The Research of GPS-Based Unmanned Substation Equipment Failure Positioning Systems
 [PDF]

祝骊伟, 钱洲亥,, 周海飞,
Smart Grid (SG) , 2014, DOI: 10.12677/SG.2014.44023
Abstract:
无人值守变电站的快速发展,越发凸显出变电站中设备状态监测的重要性,本文提出了一种基于GPS卫星系统的无人值守变电站故障设备定位系统;介绍了该系统的功能、结构;着重分析了该系统定位原理。该系统采用GPS伪距差分定位实现了变电站设备定位功能,并通过有效采集变电站中各设备状态信息反馈到控制中心,从而实现故障设备的精确定位。
The rapid development of unattended transformer substation highlights its importance of equip-ment condition monitoring. This paper proposed a faulty equipment positioning system in unat-tended transformer substation based on a GPS satellite system, introduced the system’s function, structure and focused on analyzing the system’s positioning principle. The system uses GPS pseu-dorange differential positioning to achieve the location of transformer substation’s equipment, and by feedback the effective collected information of each substation device status to the control center, enabling precise positioning of the failed device.
利用时温等效原理修正的VARTM用双酚F型环氧树脂体系化学流变模型
,,
复合材料学报 , 2010,
Abstract: 研究了A40/DDM/DMTDA复合体系固化双酚F型环氧树脂体系的化学流变特性,建立了该体系在恒温和动态升温情况下的双阿伦尼乌斯黏度模型。以100℃为参考温度,研究了该体系的时温等效效应,通过转换因子aT的偏移预测了其它温度点的黏度-时间曲线。并应用时温等效原理,修正了所建立的恒温模型,克服了原模型在黏度值较大时与实验值的偏差。修正后的双阿伦尼乌斯模型的黏度预测值在较大的黏度范围内与实验结果保持良好的一致性,可有效地预测VARTM工艺过程的黏度变化,为复合材料成型工艺模拟分析及工艺参数的确定奠定了基础。
基于遥感和GIS的生物质能集约化利用
,娄全胜,
国土资源遥感 , 2010, DOI: 10.6046/gtzyyg.2010.03.01
Abstract: ?低碳经济是一种以能源的清洁开发与高效利用为基础的社会经济发展新模式。开发利用生物质能,为大中型生物质发电工程提供稳定可靠的燃料保障,这在化石燃料日益枯竭的今天具有极其重要的现实意义。利用MODIS标准初级生产力数字产品(MOD17)获取了广东省NPP(植被净初级生产力)分布图,结合由Landsat卫星影像处理生成的广东省土地利用类型图,得到了全省水稻生物质能的分布图及其统计数据。在此基础上,利用ArcGIS区域统计方法和区位配置模型筛选出了全省适宜发展水稻生物质能的最佳区位,认为肇庆、潮州附近区域比较适宜发展水稻生物质能产业。水稻生物质能定量化的估算和选址研究可为广东省开发利用水稻生物质能、发展低碳经济提供参考。
故障相的故障分量综合阻抗特点分析
,,宋弘
重庆邮电大学学报(自然科学版) , 2012,
Abstract: 使用三相模型,推导了故障分量综合阻抗与序分量综合阻抗之间的关系,指出故障相的故障分量综合阻抗在数值上与故障时的故障分量正序综合阻抗接近。同时它还具有小于两侧系统阻抗中比较大的、大于比较小的系统阻抗的特点,且在应用于弱馈系统时,故障分量综合阻抗小于线路阻抗与较小的系统阻抗的2倍之和。使用EMTP建立了500kV,400km线路模型对分析结论进行了验证。该结论可用于故障分量综合阻抗纵联保护原理的整定计算及定值灵敏度的分析。
利尿剂在高血压治疗中的地位
廖行,,
华西医学 , 2015, DOI: 10.7507/1002-0179.20150510
Abstract: 利尿剂一直作为降压治疗中不可或缺的一种药物,能显著降低心血管事件发生风险,然而其作为降压一线药物还是作为联合使用药物目前仍然存在争议。同时它对新发糖尿病、脂质代谢等方面的影响也不容忽视。现结合近年来发表的相关文献,对利尿剂在降压过程中的地位与困惑进行综述,从而为降压药的选择提供一定的参考。
扰动重力梯度张量单分量和组合分量最小二乘配置法模型的建立
,吴晓平,
地球物理学报 , 2012, DOI: 10.6038/j.issn.0001-5733.2012.05.015
Abstract: 建立了利用扰动重力梯度张量Tzz分量和Txx+Tyy、Tzz-Txx-Tyy组合分量确定地球重力场的调和分析法模型,进一步推导了扰动重力梯度张量对角线三分量的自协方差和互协方差函数的级数展开式,推导了单分量、组合分量与重力位系数之间协方差函数的实用计算公式,给出了利用单分量和组合分量解算地球重力场模型的最小二乘配置法基本原理公式.结果表明,最小二乘配置法具有一定的抗差能力,随着观测数据误差的不断增大,其恢复的重力场模型有效阶次不断降低,精度也不断下降;Tzz-Txx-Tyy组合分量解算重力场模型的精度最高,其次为Tzz分量,Txx+Tyy组合分量最差.
线性系统理论预报槐果碱在大鼠体内处置动力学
,黄圣
药学学报 , 1988,
Abstract: 用线性系统理论和生理药代动力学模型理论结合,提出一种预报槐果碱在大鼠各组织中处置动力学的数学方法,并用实验验证该方法的可靠性。结果表明数学模拟值与实验观察值基本吻合。扩展到2.5kg兔,iv25mg后和2.5mg/min滴注过程中血药浓度预示值与观察值基本一致。
磁流变液夹层板隔声性能研究
Sound Insulation Performance of the Sandwich Panel Cored with Magneto-Rheological Fluid
 [PDF]

戚利利,, 石静, , 陆安琪
Open Journal of Transportation Technologies (OJTT) , 2016, DOI: 10.12677/OJTT.2016.55015
Abstract:
本文基于波阻抗分析法建立了夹层板的传声损失数学模型,根据松弛时间谱间接估算了磁流变液的粘弹性模量,基于此理论模型,采用MATLAB编写相应的传声损失数值模拟程序,仿真研究了磁流变液夹层板的传声损失。研究结果表明,励磁电流对磁流变液夹层板的传声损失具有明显的影响,通过调节励磁电流,可以实现夹层板隔声能力的半主动控制;夹层板的芯层厚度并非越大越好,大的芯层厚度易于使吻合频率落入夹层板的常用工作频率范围,从而恶化夹层板的低频隔声性能;夹层板的面板材料选取要综合考虑夹层板的高、低频隔声能力,且要注意成本和轻量化的要求。
Mathematical model of the sound transmission loss (STL) of sandwich panels is firstly established based on the method of wave impedance analysis. And then, the viscoelastic moduli of magneto-rheological fluid are estimated indirectly according to the relaxation time spectrum. Finally, the simulation program of the STL of sandwich panels is coded by MATLAB and then the STL of sandwich panels is analyzed. Research results show that there are obvious effects of the field current on the STL, and semi-active control of the sound insulation performance of the sandwich panel can be realized by adjusting the field current; the core layer thickness of the sandwich panel is not the bigger the better because bigger thickness is easy to make the coincidence frequency fall into the common operating frequency range of sandwich panels and thus worsens the sound insulation performance of sandwich panel in low frequency range; selection of face sheet material should comprehensively consider the sound insulation performance of panels in both low and high frequency ranges, and the panel cost and lightweight requirements should also be considered.
Page 1 /298666
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.