Entity

Time filter

Source Type

Beijing, China

Du W.,Beijing City University
Journal of Convergence Information Technology | Year: 2012

This study has built a scientific and reliable logistics simulation system. Grid management model which has advantage on the aspect of logistics resource allocation has been chosen to conduct the simulation study, and by building a comparison model between grid and non-grid logistics, the average waiting number, average demand, average waiting time, average time of stay and resource utilization rate during resource allocation are used as evaluation indices to conduct comparison and analysis. The result shows that the urban logistics resource integration system based on grid management can sweep away the barriers to solve various problems in urban logistics planning, such as integration and optimization of various resources, efficient utilization and collaboration. Source


Liu Y.,University of Science and Technology Beijing | Liu Y.,Beijing City University | Hu C.,University of Science and Technology Beijing | Zhao C.,University of Science and Technology Beijing
Computer Physics Communications | Year: 2011

We present a multi-step computation method to implement the Ewald summation for long-range electrostatic interactions in molecular dynamic simulations on a multi-core machine. Our methodology is based on the OpenMP programming model. It partitions computations of real-space summation among threads so that the global force of a single particle cannot be modified by more than one thread simultaneously. It requires neither a private copy of the force array for each thread nor an inspector at runtime. Compared with some other methods that can parallelise reduction operations on a force-array, our method achieves relatively higher speedups and lower L2 cache miss and bus utilisation ratios. © 2011 Elsevier B.V. All rights reserved. Source


Wang K.C.,Beijing Normal University | Dickinson R.E.,University of Texas at Austin | Su L.,Beijing City University | Trenberth K.E.,U.S. National Center for Atmospheric Research
Atmospheric Chemistry and Physics | Year: 2012

Atmospheric aerosols affect both human health and climate. PMX is the mass concentration of aerosol particles that have aerodynamic diameters less than X 1/4m, PM10 was initially selected to measure the environmental impact of aerosols. Recently, it was realized that fine particles are more hazardous than larger ones and should be measured. Consequently, observational data for PM2.5 have been obtained but only for a much shorter period than that of PM10. Optical extinction of aerosols, the inverse of meteorological visibility, is sensitive to particles less than 1.0 1/4m. These fine particles only account for a small part of total mass of aerosols although they are very efficient in light extinction. Comparisons are made between PM10 and PM2.5 over the period when the latter is available and with visibility data for a longer period. PM10 has decreased by 44% in Europe from 1992 to 2009, 33% in the US from 1993 to 2010, 10% in Canada from 1994 to 2009, and 26% in China from 2000 to 2011. However, in contrast, aerosol optical extinction has increased 7% in the US, 10% in Canada, and 18% in China during the above study periods. The reduction of optical extinction over Europe of 5% is also much less than the 44% reduction in PM10. Over its short period of record PM2.5 descreased less than PM10. Hence, PM10 is neither a good measure of changes in smaller particles nor of their long-term trends, a result that has important implications for both climate impact and human health effects. The increased fraction of anthropogenic aerosol emission, such as from vehicle exhaust, to total atmospheric aerosols partly explains this contrasting trend of optical and mass properties of aerosols. Source


Yuan Z.,Peking Union Medical College | Zeng X.,Peking Union Medical College | Yang D.,Peking Union Medical College | Wang W.,Peking Union Medical College | And 3 more authors.
PLoS ONE | Year: 2013

Background:Emerging evidence suggests that single nucleotide polymorphisms (SNPs) in microRNA-coding genes may participate in the pathogenesis of lung cancer by altering the expression of tumor-related microRNAs. Several studies were investigated in recent years to evaluate the association between hsa-miR-196a2 rs11614913 polymorphism and increased/decreased lung cancer risk. In the present study, we performed a meta-analysis to systematically summarize the possible association.Methodology/Principal Findings:We performed a meta-analysis of 4 case-control studies that included 2219 lung-cancer cases and 2232 cancer-free controls. We evaluated the strength of the association using odds ratios (ORs) with 95% confidence intervals (CIs). In the overall analysis, it was found that the rs11614913 polymorphism significantly elevated the risk of lung cancer (CC versus (vs.) TT OR = 1.26, 95% CI 1.07-1.49, P = 0.007; CC/CT vs. TT: OR = 1.13, 95% CI 0.98-1.29, P = 0.007; C vs. T: OR = 1.12, 95% CI 1.03-1.22, P = 0.008). In the subgroup analysis by ethnicity, statistically significantly increased cancer risk was found among Asians (CC vs. TT: OR = 1.30, 95% CI 1.10-1.54, P = 0.003; CT vs. TT: OR = 1.16, 95% CI 1.01-1.34, P = 0.039; CC vs. CT/TT: OR = 1.21, 95% CI 1.04-1.41, P = 0.012; C vs. T: OR = 1.14, 95% CI 1.05-1.25, P = 0.002). For Europeans, a significant association with lung cancer risk was found in recessive model (CC vs. CT/TT: OR = 0.63, 95% CI 0.40-0.98, P = 0.040). No publication bias was found in this study.Conclusions/Significance:Our meta-analysis suggests that the rs11614913 polymorphism is significant associated with the increased risk of lung cancer, especially in Asians. Besides, the C allele of rs11614913 polymorphism may contribute to increased lung cancer risk. © 2013 Yuan et al. Source


Gao Q.,Beijing City University
Applied Mechanics and Materials | Year: 2013

This paper presented a kind of robot self-protection system which was a combination of photoelectric sensor and ultrasonic sensor. In this study, signals were gathered by using the complement of ranging of photoelectric sensor and ultrasonic sensor. Then the signals were sent to MCU to achieve multi-sensors information fusion.With such function, an accurate robot self-protection command was made as to avoid obstacles, to judge narrow highland and to prevent dropping. The experiment results validate its good self-protection function. © (2013) Trans Tech Publications, Switzerland. Source

Discover hidden collaborations