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Search Results: 1 - 10 of 81014 matches for " Yongfu Liu "
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Numerical Analysis of Reinforcement Structure Stability Based on the Stress State of Geogrid  [PDF]
Xiaosong Tang, Yongfu Wang, Zhixiang Liu
World Journal of Engineering and Technology (WJET) , 2018, DOI: 10.4236/wjet.2018.62023
Abstract: The reinforcement effect of geogrids is exerted through the fixing and occlusion with the surrounding soil to ensure the stability of reinforced structure. Based on the friction reinforced mechanism, the geogrids play the role of anti-shear and anti-pulling. So the indexes of interface strength identified by shear and tensile tests?are?usually used to conduct the stability analysis of reinforced structure. At present, the same indexes of interface strength?areadopted in the stability analysis of reinforced structure, where only one of the anti-shearing action or anti-pulling effect of geogrid is considered, which is separated from the practical stress state of geogrids and has certain limitation. To solve the problem, the paper adjusts the interface indexes of geogrids based on the potential sliding surface and the stress state of geogrids when the failure happens. So the method of stability analysis is concluded where cyclic iterative analysis is carried out till the interface characters of geogrids and the unstable mode of the whole structure are the same. The calculation examples of reinforced soil slope in the paper shows that the method can fully reflect the reinforcement of geogrids and can complete the adoption of numerical method in the stability analysis of reinforcement structure.
The isotopic abundance and atomic weight of natural uranium
Yongfu Liu,Shuchun Fu
Chinese Science Bulletin , 1997, DOI: 10.1007/BF02882489
Abstract: The published measurement data of atomic weight of uranium are shown in table 4[9]. The best results are those measured by Smith and Cowanet al. A r (U) = 238.028 79–238.028 90(3), their result error being ISD. The evaluated value of IUPAC-CAWIA is Ar(U)=238.028 9(1). In this work, the result is Ar(U) = 238.028 91(4). The combined uncertainty has been given according to 2SD of the measurement data through the calibration of a series of standard materials of uranium isotopes. It is reasonable to conclude that in this work the uncertainty which characterizes the measurement quality is better than other published data.
Flocking for Leader-Following Multi-Agent Systems with Time-Varying Delay  [PDF]
Fenglan Sun, Rui Wang, Yongfu Li, Feng Liu
Intelligent Control and Automation (ICA) , 2016, DOI: 10.4236/ica.2016.71002
Abstract: This paper investigates the flocking problem in multi-agent system with time-varying delay and a virtual leader. Each agent here is subject to nonlinear dynamics. For the system, the corresponding algorithm with time-varying delay is proposed. Under the assumption that the initial network is connected, it is proved that the distance between agents is in the desired distance. The theoretical deduction shows that the stable flocking motion is achieved.
Numerical simulations of intense meiyu rainfall in 1991 over the changjiang and huaihe river valleys by a regional climate model with p- σ incorporated coordinate system
Numerical Simulations of Intense Meiyu Rainfall in 1991 over the Changjiang and Huaihe River Valleys by a Regional Climate Model with p-б Incorporated Coordinate System

Liu Huaqiang,Qian Yongfu,
Liu Huaqiang
,Qian Yongfu

大气科学进展 , 1999,
Abstract: Based on the primitive equation model with p- σ incorporated coordinate system originally developed by Qian et al., a one-way nested fine mesh limited area model is developed. This model is nested with ECMWF T42 data to simulate the extra-intensive rainfall event occurring in the Changjiang and Huaihe River valleys in summer of 1991. The results show that the model has certain capacity to fairly reproduce the regional distribution and the movement of the main rainfall belts. Therefore it can be used as a regional climate model to simulate and predict the short-range regional climate changes. Jointly Sponsored by the National Natural Science Foundation of China (No. 49735170) and the Key Project of the National Fundamental Research “ Climate Dynamics and Prediction Theory .
The isotopic abundance and atomic weight of natural uranium

Yongfu Liu,Shuchun Fu,

科学通报(英文版) , 1997,
Abstract: Conclusion The published measurement data of atomic weight of uranium are shown in table 49]. The best results are those measured by Smith and Cowanet al. A r (U) = 238.028 79–238.028 90(3), their result error being ISD. The evaluated value of IUPAC-CAWIA is Ar(U)=238.028 9(1). In this work, the result is Ar(U) = 238.028 91(4). The combined uncertainty has been given according to 2SD of the measurement data through the calibration of a series of standard materials of uranium isotopes. It is reasonable to conclude that in this work the uncertainty which characterizes the measurement quality is better than other published data.
Impacts of land surface and sea surface temperatures on the onset date of the South China Sea summer monsoon

Peng Liu,Yongfu Qian,Anning Huang,

大气科学进展 , 2009,
Abstract: The present study analyzes the differences in spatial and temporal variations of surface temperatures between early and late onset years of the South China Sea summer monsoon (SCSSM). It is found that when the land surface temperature north of 40°N is lower (higher) and the sea surface temperature over the South China Sea-western North Pacific (SCS-WNP) is higher (lower) in winter, the onset of the SCSSM begins earlier (later). When the land surface temperature north of 40°N is higher (lower) and the sea surface temperature over the SCS-WNP is lower (higher) in spring, the onset of the SCSSM occurs earlier (later). The reason why the anomalies of the land surface temperatures north of 40°N can influence the atmospheric circulation is investigated by analysis of the wind and temperature fields. In order to verify the mechanisms of influence over the land and sea surface temperature distribution patterns and test the ability of the p-σ regional climate model (p-σ RCM9) to simulate the SCSSM onset, three types of years with early, normal, and late SCSSM onset are selected and the SCSSM regimes are numerically simulated. According to the results obtained from five sensitive experiments, when the land surface temperature is higher in the eastern part, north of 40°N, and lower in the western part, north of 40°N, and it rises faster in the eastern coastal regions and the Indian Peninsula, while the sea surface temperatures over the SCS-WNP are lower, the early onset of the SCSSM can be expected.
An Iterative Algorithm of Solution for Quadratic Minimization Problem in Hilbert Spaces
Li Liu,Guanghui Gu,Yongfu Su
Journal of Inequalities and Applications , 2010, DOI: 10.1155/2010/717341
Abstract: The purpose of this paper is to introduce an iterative algorithm for finding a solution of quadratic minimization problem in the set of fixed points of a nonexpansive mapping and to prove a strong convergence theorem of the solution for quadratic minimization problem. The result of this article improved and extended the result of G. Marino and H. K. Xu and some others.
An Iterative Algorithm of Solution for Quadratic Minimization Problem in Hilbert Spaces
Liu Li,Gu Guanghui,Su Yongfu
Journal of Inequalities and Applications , 2010,
Abstract: The purpose of this paper is to introduce an iterative algorithm for finding a solution of quadratic minimization problem in the set of fixed points of a nonexpansive mapping and to prove a strong convergence theorem of the solution for quadratic minimization problem. The result of this article improved and extended the result of G. Marino and H. K. Xu and some others.
Effects of Nested Area Size upon Regional Climate Model Simulations
嵌套域大小对区域气候模式模拟效果的影响

Liu Huaqiang,Qian Yongfu,Zheng Yiqun,
Liu Huaqiang
,Qian Yongfu,Zheng Yiqun

大气科学进展 , 2002,
Abstract: This paper presents a numerical study on the 1998 summer rainfall over the Yangtze River valley in central and eastern China, addressing effect of a nested area size on simulations in terms of the technique of nesting a regional climate model (RCM) upon a general circulation model (GCM). Evidence suggests that the size exerts greater impacts upon regional climate of the country, revealing that a larger nested size is superior to a small one for simulation in mitigating errors of GCM-provided lateral boundary forcing. Also, simulations show that the RCM should incorporate regions of climate systems of great importance into study and a low-resolution GCM yields more pronounced errors as a rule when used in the research of the Tibetan Plateau, and, in contrast, our PORCM can do a good job in describing the plateau's role in a more realistic and accurate way. It is for this reason that the tableland should be included in the nested area when the RCM is employed to investigate the regional climate. Our PJRCM nesting upon a GCM reaches more realistic results compared to a single GCM used.
NUMERICAL SIMULATION FOR A DIRECT BOX SHEAR TEST ON GRANULAR MATERIAL AND MICROSCOPIC CONSIDERATION
粒状体直剪试验的数值模拟与微观考察

Liu Sihong,Xu Yongfu,
刘斯宏
,徐永福

岩石力学与工程学报 , 2001,
Abstract: A direct box shear test on granular material is successfully simulated by means of distinct element method. Based on the simulation results, a method is proposed to consider the effect of frictional resistances between the upper shear box and the sample on the measured shear strength when the sample is dilated during shearing. The overall strains in the sample are evaluated. The macro stress strain relations on the shear plane are related to the micro structural quantities of particles comprising the sample.
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