Post Doctoral Research Center

Beijing, China

Post Doctoral Research Center

Beijing, China

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Xie S.,Post Doctoral Research Center | Li J.,Huazhong University of Science and Technology | Luo T.,Huazhong University of Science and Technology | Zhang Y.,Huazhong University of Science and Technology | And 3 more authors.
2016 33rd International Conference on Lightning Protection, ICLP 2016 | Year: 2016

Natural lightning flashes are stochastic and uncontrollable, and thus it is difficult to observe the formation process of a downward negative stepped leader (NSL) directly and in detail. In this paper, the formation processes of NSLs in controllable laboratorial long-Air-gap discharge experiments were studies. First, a series of negative long-Air-gap discharge experiments with scales of 4~10 m were designed and carried out. According to the observation results of these experiments, two kinds of formation processes for NSLs with different scales were presented, and several of the characteristic parameters, including the scale, the propagation velocity and the dark period, were obtained. By comparing these characteristics with that in natural flashes, the similarity between the NSLs in the simulation experiments and those in natural flashes was proved, and the actual formation of NSLs in natural flashes was deduced. © 2016 IEEE.


Shang Y.,University of Chinese Academy of Sciences | Shang Y.,Post Doctoral Research Center | Zheng G.,The Peoples Bank of China | Shao Y.,CAS Academy of Mathematics and Systems Science
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2016

The research on impact of the exchange rate on China's export is significantly important both theoretically and practically. Considering the internal imbalance and the export cycle as two conditions, this paper investigated the asymmetric impact of the exchange rate on China's export from a new perspective based on multiple regime smooth transition regression models (MRSTR). The main results show that: 1) There is less impact of the exchange rate on China's export when the degree of internal imbalance is serious, while the power of impact increases with an improvement of internal imbalance; 2) The fluctuation of export cycle does not significantly affect the impact of the exchange rate on China's export if the degree of internal imbalance is serious, but the impact of the exchange rate on China's export is significantly increased in the export boom phase than that in the export bust phase when the degree of internal imbalance is low. © 2016, Editorial Board of Journal of Systems Engineering Society of China. All right reserved.


Guo B.,Nanjing Forestry University | Guo B.,Post Doctoral Research Center | Wang L.-J.,Nanjing Forestry University | Yin P.,Nanjing Forestry University | And 3 more authors.
Journal of Thermoplastic Composite Materials | Year: 2017

The ultra-high molecular weight polyethylene (UHMWPE) fibers, as the fibrous morphology of polyethylene (PE), were first used to reinforce thermoplastic starch (TPS) by a twin screw extruder. The influence of the UHMWPE content on the mechanical and dynamic mechanical thermal properties, thermal stability, contact angle, torque rheological properties, and fractured surface morphology of the UHMWPE/TPS composites was studied in detail. We found that the UHMWPE fibers were well dispersed in the TPS matrix, and the mechanical properties and water resistance of the composites improved significantly. Especially, the incorporation of UHMWPE fibers at a content of 2 wt% generated a composite with better performance (tensile strength of 8.78 MPa and contact angle of 80.2°). © SAGE Publications.


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.


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.


Dan H.-C.,Central South University | Dan H.-C.,Post doctoral Research Center | He L.-H.,Central South University | Zhao L.-H.,Post doctoral Research Center | And 2 more authors.
International Journal of Pavement Engineering | Year: 2015

Based on the Boit's theory, the governing equation was established to account for the response of moisture pavement. The analytical solutions were obtained through the expansion of Fourier series. Furthermore, the effects of parameters (i.e. hydraulic conductivity, traffic load velocity, drainage boundary and solid modulus) on dynamic response were investigated in terms of water-induced damage of pavement. Compared with the dry-elastic pavement, the negative normal stress in saturated asphalt pavement is concentrated beneath the traffic load, which may be a reason for a damage phenomenon in asphalt pavement. Hydraulic conductivity anisotropy plays a significant role in influencing the physical fields. Between vertical and horizontal hydraulic conductivity, the physical field almost depends on vertical hydraulic conductivity rather than horizontal hydraulic conductivity which just affects the horizontal pore-water velocity obviously. Moreover, the drained boundary evidently influences the seepage field of surface course with high permeability. © 2015 Taylor and Francis.


Sun J.,General Hospital of Jinan 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.


Wang L.,Yangtze University | Deng L.,Post Doctoral Research Center | Jiao Y.,Chinese Academy of Agricultural Sciences
Acta Agriculturae Scandinavica Section B: Soil and Plant Science | Year: 2016

SymRK and GmFWL1 both play important roles in nodulation. However, during symbiotic development, the details of Nod factor signaling association with the regulation of cell division in nodules are unknown. SymRK, the immediately downstream component of these Nod factor receptors, is central to the Nod factor signaling cascade. In this study, specified RNAi plasmid of GmSymRK was constructed and transformed into soybean roots by agrobacterium rhizogenes-mediated hairy root transformation. We found that the nodule number decreased substantially in GmSymRK knockdown soybean transgenic roots. Further to study the relationship between GmFWL1 and Nod factor signaling, we analyzed the GmFWL1 expression levels in the GmSymRK RNAi soybean transgenic roots and found that rhizobia inoculation led to substantially reduced GmFWL1 expression in GmSymRK RNAi soybean transgenic roots. Our studies showed that the regulation of cell division was affected by Nod factor signaling during nodule development in soybean, which provides important information toward understanding the functions of GmSymRK and GmFWL1 in symbiotic signaling and nodule development. © 2016 Informa UK Limited, trading as Taylor & Francis Group


Dan H.-C.,Central South University | Dan H.-C.,Post doctoral Research Center | He L.-H.,Central South University | Xu B.,Central South University
Transport in Porous Media | Year: 2016

The unbound graded aggregate base (UGAB) has been widely used in drainage layers of highway pavements. This kind of material is of high permeability and can thus drain efficiently the water infiltrated through cracks in the pavement and reduce the associated water damage. The hydraulic conductivity of UGAB is a key factor describing the water flow behavior in UGAB and thus be considered primarily in the design of highway drainage engineering. In this study, the flow behavior of UGAB material was investigated through constant head permeability experiments. Based on the Reynolds number analysis, it was found that the flow in UGAB material was non-Darcian even though under relatively low hydraulic gradient. Therefore, the Darcy law cannot be directly applied to determine the hydraulic conductivity of UGAB. Furthermore, the empirical expression of coefficients in Forchheimer equation, which can be available to evaluate hydraulic conductivity of UGAB material approximately, is presented incorporating the representative particle size and porosity based on the Ergun equation. Then, it was validated against the aid of normalized objective function analysis. Through comparison analysis, the sequencing of hydraulic conductivity of UGAB material was sorted quantitatively in terms of different gradation and representative particle size ((Formula presented.) and (Formula presented.)). The results also showed that the (Formula presented.)(Formula presented.) and the content of fine particles (<0.075 mm) are appropriate indexes for the gradation design of UGAB material in highway pavement engineering. © 2016 Springer Science+Business Media Dordrecht


Dan H.-C.,Central South University | Dan H.-C.,Post doctoral Research Center | Dan H.-C.,National Engineering Laboratory for Mountain Traffic Disaster Prevention and Control Technology Guizhou | He L.-H.,Central South University | And 4 more authors.
Cold Regions Science and Technology | Year: 2014

Currently, there are few quantitative studies on the adhesion of ice to the asphalt pavement surface. In this paper, a large-scale freezing laboratory is employed to simulate the low-temperature and wet environment, and a full-scale asphalt pavement model is constructed in the freezing laboratory. The experimental schemes are developed to measure the magnitudes of the normal and horizontal adhesive force of ice to the rough asphalt pavement surface. Then, the normal and horizontal adhesive strength of ice is evaluated to quantify the adhesive force per unit rough area, and the effects of ice temperature as well as the mean texture depth of asphalt pavement on the ice adhesive strength are taken into consideration. Based on the test and evaluation results, it is found that the normal and horizontal ice adhesive strength increases with the ice temperature decrease. The adhesive strength in the normal direction exhibits a logarithmic relation to the ice temperature whereas that in the horizontal direction shows a linear relation. The adhesive strength of ice to the asphalt pavement with higher mean texture depth (0.65. mm) is stronger than that with the lower mean texture depth case (0.50. mm). © 2014 Elsevier B.V.

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