检索结果-南通市图书馆

Numerical modeling of flow in continuous bends from Daliushu to Shapotou in Yellow River

在线全文

学校读者我要写书评

暂无评论

Water Science and Engineering 2014年第2期7卷 194-207页

作者： He-fang JING Chun-guang li Ya-kun GUO li-jun ZHU yi-tian li School of Civil Engineering Beifang University of Nationalities School of Engineering University of Aberdeen School of Mathematics and Information Science Beifang University of Nationalities State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University

The upper reach of the Yellow River from Daliushu to Shapotou consists of five bends and has complex topography. A two-dimensional Re-Normalisation Group （RNG） k-ε model was developed to simulate the flow in the reach. In order to take the circulation currents in the bends into account, the momentum equations were improved by adding an additional source term. Comparison of the numerical simulation with field measurements indicates that the improved two-dimensional depth-averaged RNG k-e model can improve the accuracy of the numerical simulation. A rapid adaptive algorithm was constructed, which can automatically adjust Manning＇s roughness coefficient in different parts of the study river reach. As a result, not only can the trial computation time be significantly shortened, but the accuracy of the numerical simulation can also be greatly improved. Comparison of the simulated and measured water surface slopes for four typical cases shows that the longitudinal and transverse slopes of the water surface increase with the average velocity upstream. In addition, comparison was made between the positions of the talweg and the main streamline, which coincide for most of the study river reach. However, deviations between the positions of the talweg and the main streamline were found at the junction of two bends, at the position where the river width suddenly decreases or increases.

关键词： numerical simulation RNG k-e model Yellow River continuous bend circulationflow adaptive algorithm regarding Manning's roughness coefficient

Impact of water and sediment discharges on subaqueous delta evolution in Yangtze Estuary from 1950 to 2010

在线全文

学校读者我要写书评

暂无评论

Water Science and Engineering 2014年第3期7卷 331-343页

作者： Yun-ping YANG yi-tian li Yong-yang FAN Jun-hong ZHANG Key Laboratory of Engineering Sediment Tianjin Research Institute for Water Transport EngineeringMinistry of Transport State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University

In order to determine how the subaqueous delta evolution depends on the water and sediment processes in the Yangtze Estuary, the amounts of water and sediment discharged into the estuary were studied. The results show that, during the period from 1950 to 2010, there was no significant change in the annual water discharge, and the multi-annual mean water discharge increased in dry seasons and decreased in flood seasons. However, the annual sediment discharge and the multi-annual mean sediment discharge in flood and dry seasons took on a decreasing trend, and the intra-annual distribution of water and sediment discharges tended to be uniform. The evolution process from deposition to erosion occurred at the -10 m and -20 m isobaths of the subaqueous delta. The enhanced annual water and sediment discharges had a silting-up effect on the delta, and the effect of sediment was greater than that of water. Based on data analysis, empirical curves were built to present the relationships between the water and sediment discharges over a year or in dry and flood seasons and the erosion/deposition rates in typical regions of the suhaqueous delta, whose evolution followed the pattern of silting in flood seasons and scouring in dry seasons. Notably, the Three Gorges Dam has changed the distribution processes of water and sediment discharges, and the dam＇s regulating and reserving functions can benefit the subaqueous delta deposition when the annual water and sediment discharges are not affected.

关键词： water discharge sediment discharge, seasonal change delta Yangtze Estuary

Recent Advances in Carbon-Based Adsorbents for Adsorptive Separation of light Hydrocarbons

在线全文

学校读者我要写书评

暂无评论

Research 2022年第4期2022卷 261-281页

作者： Yong-Sheng Wang Xue-Jie Zhang Ya-Qi Ba tian-yi li Guang-Ping Hao An-Hui Lu State Key Laboratory of Fine Chemicals Liaoning Key Laboratory for Catalytic Conversion of Carbon ResourcesSchool of Chemical EngineeringDalian University of TechnologyDalian 116024China

light hydrocarbons(LHs)separation is an important process in petrochemical *** current separation technology predominantly relies on cryogenic distillation,which results in considerable energy *** separation using porous solids has received widespread attention due to its lower energy footprint and higher ***,tremendous efforts have been devoted to the design and synthesis of high-performance porous *** them,porous carbons display exceptional stability,tunable pore structure,and surface chemistry and thus represent a class of novel adsorbents upon achieving the matched pore structures for LHs *** this review,the modulation strategies toward advanced carbonbased adsorbents for LHs separation are firstly ***,the relationships between separation performances and key structural parameters of carbon adsorbents are discussed by exemplifying specific separation *** research findings on the control of the pore structures as well as the quantification of the adsorption sites are ***,the challenges of carbonaceous adsorbents facing for LHs separation are given,which would motivate us to rationally design more efficient absorbents and separation processes in future.

关键词： separation adsorbent porous

Cyclometallated iridium phosphors with amino acid ancillary ligand for intracellular imaging

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2016年第10期27卷 1582-1585页

作者： tian-yi li Hua-Chao Chen yi-Ming Jing Hua-Bo Han Xiao liang You-Xuan Zheng Wei-jiang He State Key Laboratory of Coordination Chemistry Collaborative Innovation Center of Advanced MicrostructuresSchool of Chemistry and Chemical EngineeringNanjing University

Two new iridium complexes, （dfppy）2Ir（L-alanine）（dfppy-2-（2,4-difluorophenyl）pyridine） and （piq）21r（L-alanine）（piq - 1-phenylisoquinoline） were prepared with L-alanine as ancillary ligand. The two complexes show bright greenish-blue and red emission respectively. Theoretic study demonstrated that the emission nature of these complexes is mainly determined by the main ligand. And their improved aqueous solubility and the retained quantum yield favor their application in cell imaging. Intracellular imaging suggested that these two complexes have fine cell membrane permeability and is mainly distributed in cytoplasm. This study displayed a new strategy to design aqueous soluble phosphorescent cyclometallated if（Ⅲ） complex via introducing amino acid as ancillary ligand.

关键词： Iridium complexL-AlanineWater solubilityPhosphorescent materialsCell imaging

Numerical study of the flow in the Yellow River with non-monotonous banks

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2016年第1期28卷 142-152页

作者：景何仿李义天李春光 State Key Laboratory of Water Resources and Hydropower Engineering Sciences Wuhan University Research Institute of Numerical Computation and Engineering Applications North University for Nationalities

A 2-D depth averaged RNG k- ε model is developed to simulate the flow in a typical reach of the Upper Yellow River with non-monotonic banks. In order to take account of the effect of the secondary flow in a bend, the momentum equations are modified by adding an additional source term. A comparison between the numerical simulation and the field measurements indicates that the improved 2-D depth averaged RNG k- ε model can improve the accuracy of the numerical simulation. An arc spline interpolation method is developed to interpolate the non-monotonic river banks. The method can also be reasonably applied for the 2-D interpolation of the river bed level. Through a comparison of the water surface gradients simulated in the seven bends of the studied reach, some analytical formulae are improved to reasonably calculate the longitudinal and transverse gradients in meandering river reaches. Furthermore, the positions of the maximum water depth and the maximum velocity in a typical bend are discussed.

关键词： 2-D RNG k-ε model numerical simulation extra source term arc cubic spline interpolation non-monotonic bank

在线全文

学校读者我要写书评

暂无评论

光学全息的数字实现

光学精密工程 2005年第z1期13卷 15-20页

作者：潘武田贻丽重庆邮电学院微光机电系统研究所重庆400065

研究光学全息的数字模拟,探讨数字全息的数字重构方法,以菲涅耳衍射积分的实现方法为基础,采用MATLAB软件实现菲涅耳全息图的数字记录和数字重构模拟,给出模拟结果。利用离散菲涅耳衍射积分方法完成数字全息图的数字重构。利用数字图像... 详细信息

研究光学全息的数字模拟,探讨数字全息的数字重构方法,以菲涅耳衍射积分的实现方法为基础,采用MATLAB软件实现菲涅耳全息图的数字记录和数字重构模拟,给出模拟结果。利用离散菲涅耳衍射积分方法完成数字全息图的数字重构。利用数字图像处理方法对所得的数字全息图进行适当滤波处理,有利于消除零级像和孪生像,获得清晰的数字再现像。引入全息变换,根据全息图的不可撕毁性,研究了全息变换在数字图像压缩中的应用,对给定的二值化图像实现压缩存储及解压缩处理。

关键词：数字全息数字模拟重构图像压缩

An Improved Adaptive Median Filter for Image Denoising

在线全文

学校读者我要写书评

暂无评论

An Improved Adaptive Median Filter for Image Denoising

Numerical study of the flow and dilution behaviors of round buoyant jet in counterflow

2010 3rd International Conference on Computer and Electrical Engineering(ICCEE 2010)

作者： Chun-mei WANG tian-yi li Department of Computer Science Sichuan University

In this paper, we proposed a new adaptive median filter for image denoising. In our method, two thresholds have been involved for detecting noises in variable-sized windows. The median filter and the mean filter are combined for changing the value of the corrupted pixels. The filter can preserve the fine details of image while suppressing the impulsive-type noise. The results of the experiments proved that our method is better than the traditional median filters.

关键词： salt & pepper noise adaptive median filter standard median filter extreme median filter

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2017年第1期29卷 172-175页

作者：高猛槐文信李义天王伟杰 State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China

Pollutants are usually discharged into the receiving water bodies in the form of a turbulent jet or plume, and the presence of a counterflow enhances the initial dilution of the jet effluent. To understand the behaviors of jets in actual situations, a round buoyant jet issued horizontally into a uniform counterflow is simulated for different combinations of densimetric Froude number and jet-to-current velocity ratio. A two-phase mixture model is used to simulate this flow, and the renormalization group k - ε model is used to address the flow turbulence. The inter-phase interactions are described in terms of the relative slip velocity between phases. The jet features, including the trajectory of the jet centerline and the decay of the centedine velocity and the concentration, are investigated. The length scale analysis reveals the relationships between the distance and the centerline dilutions, and different flow mechanisms are revealed before and after the penetration point.

关键词： Buoyant jet counterflow mixture model velocity decay concentration dilution

在线全文

学校读者我要写书评

暂无评论

红外/微波波束合成器近场均匀性分析

北京理工大学学报 2016年第10期36卷 1079-1084页

作者：严辉田义王欣李卓北京理工大学光电学院北京100081

针对矩量法(MoM)计算电大尺寸介质近场分布的低效率,提出使用口径场积分法(AFIM)分析红外/微波波束合成器近场均匀性,对比表明,AFIM相对MoM偏差小于10%,计算时间从数小时缩短至数秒.以电场分布曲线的标准差为均匀性指标,计算表明波束合... 详细信息

针对矩量法(MoM)计算电大尺寸介质近场分布的低效率,提出使用口径场积分法(AFIM)分析红外/微波波束合成器近场均匀性,对比表明,AFIM相对MoM偏差小于10%,计算时间从数小时缩短至数秒.以电场分布曲线的标准差为均匀性指标,计算表明波束合成器近场均匀性关于D^2/λL成负幂函数关系(D为波束合成器口径,L为近场距离,λ为波长).将该负幂函数用于波束合成器外形尺寸优化,优化结果通过MoM进行验证,相对偏差小于10%.

关键词：波束合成器矩量法口径场积分近场计算