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Chen J.-Q.,Central South University | Chen J.-Q.,Rutgers University | Li L.,Central South University | Zhao L.-H.,Central South University | And 3 more authors.
Journal of Central South University | Year: 2014

In order to simplify the boundary conditions of pavement temperature field, the "Environment-Surface" system which considered the natural environment and pavement surface was established. Based on this system, the partial differential equations of the one-dimensional heat conduction in the pavement were established on the basis of the heat transfer theory. Furthermore, the function forms of the initial and boundary conditions of the equations were created through the field experiments. The general solution of the pavement one-dimensional heat conduction partial differential equations was acquired by using Green's function, and the explicit expression of pavement temperature field under specific constraint conditions was derived. For the purpose of analysis, the pavement temperatures in different seasons were calculated using the explicit expression of pavement temperature field, and the calculation accuracy was analyzed through the comparison between measured and calculated values. Then, the relationship between fitting accuracy and calculation accuracy of pavement temperatures was analyzed. The analysis results show that: the usage of "Environment-Surface" system simplifies the calculation of pavement temperature field; the relative error between calculated and measured values is generally less than 7% and is seldom influenced by seasons; there is a positive correlation between the calculation accuracy and the fitting accuracy of pavement surface temperature; high fitting accuracy would result in less error of pavement temperature prediction. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg. Source


Yan Y.,University of Chinese Academy of Sciences | Yan Y.,Post doctoral Research Center | Zhu X.-W.,China University of Political Science and Law | Xiong A.-M.,Ningbo University | And 2 more authors.
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2011

This research selected 28 main stock indexes of the world as a sample, in which the year of 2004-2006 was viewed as stable period, and the year of 2007-2009 was viewed as crisis period. The probability density distributions of daily logarithmic returns were fitted with normal distribution curves and t-distribution curves, calculated with the number of freedom degrees ν and scale parameter b. The Kolmogorov-Smirnov test shows that t-distribution fits the data better than normal distribution. The investigation shows that the risks of stock markets are much higher during the financial crisis. During the stable period, almost all the ν-values are larger than 2 with the medium of 2.64, in accordance with that ν-value is approximately 3 in existing literatures. During the financial crisis, ν-values are smaller than 2 in most cases, except China, and the characters of t distribution curves have been changed. Because of the variation limit polity in Shenzhen and Shanghai Stock markets, there are no significant variations of ν-values for Chinese stock indexes, which are approximately 3 before and after financial crisis. Source


Sun J.,General Hospital of Shenyang Military Command | Sun J.,Post doctoral Research Center | Yuan W.-A.,Shanghai University of Traditional Chinese Medicine | Lu H.,Shanghai University of Traditional Chinese Medicine | And 2 more authors.
International Journal of Clinical and Experimental Medicine | Year: 2015

Patient-Reported Outcomes (PROs) data are increasingly common and widely accepted in clinical investigations of symptoms. Agreements or differences regarding Doctor-Report Outcomes (DROs) VS PROs data are unclear. In this study, we conducted a clinical trial and investigated the agreement levels of DROs VS PROs in symptoms of diabetics. This study had a parallel self-controlled and double blind design. In total, 90 diabetics who presented with the required symptoms were enrolled in this study, and 83 patients completed the study. The severity (none, mild, moderate, and severe) of each symptom was consistently compared with the Visual Analogue Scale (VAS) for the PROs measure and the numerical rating scales (NRS) for the DROs measure. The Kappa index was used to test the agreement in the variables. Our results show that most of the agreements regarding DROs VS PROs were moderate; few were modest and substantial. However, the DROs data failed to agree with the PROs data well in which symptoms effective evaluation criteria overlapped with the inclusion criteria. We believe this results are caused by distortion of information during the doctor’s decision process. We suggest that the effective evaluation criteria should not be overlapped with the inclusion criteria in the DROs design. And if it is unavoidable, PROs design should be worth considering. © 2015, E-Century Publishing Corporation. All rights reserved. Source


Jia F.,Beijing Jiaotong University | Jia F.,Post doctoral Research Center | Jia F.,Beijing Building Construction Research Institute Co. | He K.,Beijing Building Construction Research Institute Co. | And 3 more authors.
Tiedao Xuebao/Journal of the China Railway Society | Year: 2016

Specimens with dimension of 100 mm×100 mm×100 mm were tested to investigate the influence of Reactive Powder Concrete (RPC) steel fiber content, interface treatment, pouring direction and strength of Normal Concrete (NC) on the splitting tensile bonding properties of RPC/NC, and to analyze bonding mechanism between the two. Experimental results showed that RPC/NC exhibited excellent bonding performance. Three failure modes included bonding interface failure, bonding interface failure with NC cracking and NC rupture. Steel fibers in RPC could enhance interfacial roughness, improve mechanical interlocking between RPC and NC, and crack resistance. Splitting tensile bonding strength increased with the increase of steel fibers. The interfacial roughness of RPC/NC was improved by using the cleaving surface as the bonding surface, resulting in higher splitting tensile bonding strength than that of the natural surface of the specimens. The splitting tensile bonding strength with horizontal pouring was greater than that with vertical pouring, about 1.1~1.3 times higher and increased with the increasing of NC strength. © 2016, Editorial Office of Journal of the China Railway Society. All right reserved. Source


Liu Z.,Post doctoral Research Center | Liu Z.,Tsinghua University | Zhang R.,Beijing Building Construction Research Institute Co.
Advanced Materials Research | Year: 2012

Cable is widely used in the actual project of prestressed steel structure for its mechanical properties can be fully used. Saddle-shaped cable net is a new type of large-span prestressed structure, but there is little study on the impact of different cable types on the mechanical properties of saddle-shaped cable net during the construction. In order to meet the thought of integration of design and construction, a finite element model of saddle-shaped cable net has been established. The four types of cables such as semi-parallel steel tendon cable, steel wire rope cable, steel strand cable and full-locked coil rope are chosen. The impact on mechanical properties of the structure was analyzed by different cable types. © (2012) Trans Tech Publications. Source

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