Aerodynamic effect of wind barriers and running safety of trains on high-speed railway bridges under cross winds

Weiwei Guo,He Xia,Raid Karoumi,Tian Zhang,Xiaozhen Li 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2

For high-speed railways (HSR) in wind prone regions, wind barriers are often installed onbridges to ensure the running safety of trains. This paper analyzes the effect of wind barriers on the runningsafety of a high-speed train to cross winds when it passes on a bridge. Two simply-supported (S-S) PCbridges in China, one with 32 m box beams and the other with 16 m trough beams, are selected to performthe dynamic analyses. The bridges are modeled by 3-D finite elements and each vehicle in a train by amulti-rigid-body system connected with suspension springs and dashpots. The wind excitations on the trainvehicles and the bridges are numerically simulated, using the static tri-component coefficients obtained froma wind tunnel test, taking into account the effects of wind barriers, train speed and the spatial correlationwith wind forces on the deck. The whole histories of a train passing over the two bridges under strong crosswinds are simulated and compared, considering variations of wind velocities, train speeds and without orwith wind barriers. The threshold curves of wind velocity for train running safety on the two bridges arecompared, from which the windbreak effect of the wind barrier are evaluated, based on which a beamstructure with better performance is recommended.

Research on Multipath Data Transmission Protocol Based on Wireless Sensor Networks

Guo Weiwei 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.2

The issue of data transmission in wireless sensor networks was studied. The video data collection was chosen as the object of the study, and the quality of service (QoS) problem of video transmission was analyzed. Video applications were generally characterized by large data size and many QoS requirements, which made the transmission of video always a hard problem. In this dissertation, a cross-layer and multi-path video transmission strategy (MVTS) was presented. MVTS introduced the idea of differentiated service and multipath routing, and operated in both application layer and network layer. In application layer, different types of video frames were distinguished and marked with different tags. Then in network layer these frames were identified by the tags and MVTS forwarded them in different paths. In this way, the key frames could be sent to the sink node reliably. Simulation tests were carried out, and simulation results showed that MVTS extended the network lifetime greatly and provided better assurance for quality of video applications.

Research on Parallel Algorithm Based On Hadoop Distributed Computing Platform

Guo Weiwei,Liu Feng 보안공학연구지원센터 2015 International Journal of Grid and Distributed Comp Vol.8 No.4

With the rapid development of the 3G network, traditional calculation methods are unable to adapt to the data scene that telecom users' Network access behavior's data scale increase rapidly dozens of TB. The cloud techniques such as Hadoop platform are introduced to solve the data storage problem. The appropriate data mining algorithms are designed from the perspective of practical application. This paper improves the traditional decision tree SPRINT algorithms, proposes a parallel computing program and successfully applies to the Hadoop platform.

Aerodynamic effect of wind barriers and running safety of trains on high-speed railway bridges under cross winds

Guo, Weiwei,Xia, He,Karoumi, Raid,Zhang, Tian,Li, Xiaozhen Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.20 No.2

For high-speed railways (HSR) in wind prone regions, wind barriers are often installed on bridges to ensure the running safety of trains. This paper analyzes the effect of wind barriers on the running safety of a high-speed train to cross winds when it passes on a bridge. Two simply-supported (S-S) PC bridges in China, one with 32 m box beams and the other with 16 m trough beams, are selected to perform the dynamic analyses. The bridges are modeled by 3-D finite elements and each vehicle in a train by a multi-rigid-body system connected with suspension springs and dashpots. The wind excitations on the train vehicles and the bridges are numerically simulated, using the static tri-component coefficients obtained from a wind tunnel test, taking into account the effects of wind barriers, train speed and the spatial correlation with wind forces on the deck. The whole histories of a train passing over the two bridges under strong cross winds are simulated and compared, considering variations of wind velocities, train speeds and without or with wind barriers. The threshold curves of wind velocity for train running safety on the two bridges are compared, from which the windbreak effect of the wind barrier are evaluated, based on which a beam structure with better performance is recommended.

A facile and reliable route to prepare highly dispersive ammonium dimolybdate uniform crystals from commercial molybdenum oxide

Jun Zhang,Yanhui Guo,Weiwei Lu,Xuming Guo,Mingchen Xu,Hongbo Guo 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.5

Highly dispersive ammonium dimolybdate crystals with high purity have been prepared through reaction–evaporation–crystallization united route using commercial molybdenum oxide as starting material. The as-prepared ammonium dimolybdate uniform crystals were systematically characterized by X-ray powder diffraction, transmission-reflection optical microscope, Fourier transform infrared spectroscopy and TG-DSC thermal analysis. The Fsss grain diameter, loose packed density, and crystal-grain size distribution were also measured by the Malvern laser particle sizer. These collective characterization and analysis reveal that the ammonium dimolybdate grains are non-agglomerated uniform crystals with well normal distribution and geometric shape. The average Fsss diameter, d(0.5) and loose packed density are 433.316 mm, 470.981 mm and 1.592 g cm3, respectively, which could well meet the quality requirements for the subsequent production of molybdenum powders.

Effect of Acute hypoxia on Plasma Endothelin in Rats

Hao Weiwei,Yu Qifu,Zao Yuntao,Qin Shuqing,Zou Zhengmou,Yu Songhai,Guo Qiyu 한국항공우주의학협회 1994 항공우주의학회지 Vol.4 No.1

Curcumin protects against the intestinal ischemia-reperfusion injury: involvement of the tight junction protein ZO-1 and TNF-α related mechanism

Tian, Shuying,Guo, Ruixue,Wei, Sichen,Kong, Yu,Wei, Xinliang,Wang, Weiwei,Shi, Xiaomeng,Jiang, Hongyu The Korean Society of Pharmacology 2016 The Korean Journal of Physiology & Pharmacology Vol.20 No.2

Present study aimed to investigate the effect of curcumin-pretreatment on intestinal I/R injury and on intestinal mucosa barrier. Thirty Wistar rats were randomly divided into: sham, I/R, and curcumin groups (n=10). Animals in curcumin group were pretreated with curcumin by gastric gavage (200 mg/kg) for 2 days before I/R. Small intestine tissues were prepared for Haematoxylin & Eosin (H&E) staining. Serum diamine oxidase (DAO) and tumor necrosis factor (TNF)-${\alpha}$ levels were measured. Expression of intestinal TNF-${\alpha}$ and tight junction protein (ZO-1) proteins was detected by Western blot and/or immunohistochemistry. Serum DAO level and serum and intestinal TNF-${\alpha}$ leves were significantly increased after I/R, and the values were markedly reduced by curcumin pretreatment although still higher than that of sham group (p<0.05 or p<0.001). H&E staining showed the significant injury to intestinal mucosa following I/R, and curcumin pretreatment significantly improved the histological structure of intestinal mucosa. I/R insult also induced significantly down-regulated expression of ZO-1, and the effect was dramatically attenuated by curcumin-pretreatment. Curcumin may protect the intestine from I/R injury through restoration of the epithelial structure, promotion of the recovery of intestinal permeability, as well as enhancement of ZO-1 protein expression, and this effect may be partly attributed to the TNF-${\alpha}$ related pathway.

Coupling vibration response analysis of wind-train-bridge system considering the train-induced wind effect

Yujing Wang,Weiwei Guo,He Xia,Shanshan Wang,Man Xu 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.3

Considering the wind loads and track irregularity as external excitation, the wind-train-bridge dynamic analysis model considering the longitudinal freedom of train is established in the present study. In the model, the wind load of trainbridge system under the train-induced wind field and the combined wind field is obtained by employing Computational Fluid Dynamics (CFD) method. With the CRH2 high-speed train and a 10-span simply-supported box girder bridge as an example, the whole history of the train running on the bridge under the combined effect of train-induced wind and crosswind is simulated to analyze the dynamic response of the train-bridge system. In addition, the operational safety indicators of the train are evaluated. According to the obtained results, the dynamic response of vehicles and bridges increases with the train speed without the consideration of the crosswind. In the combined wind field, the train-induced wind exerts a greater impact on the dynamic response of the vehicle, but has a less influence on that of the bridge simultaneously. Moreover, the influence of wind velocity is greater than that of train speed. When the wind-train-bridge dynamic response analysis is carried out based on traditional methods, the calculated wind load of the train-bridge system is too high, making the calculated responses too large to be consistent with actual values.

Study on Grid Scheduling Model Based on Hierarchical Scheduling Model

Liu Feng,Guo Weiwei 보안공학연구지원센터 2015 International Journal of Grid and Distributed Comp Vol.8 No.3

In order to solve the task allocation and scheduling problem based on the analysis and research of hierarchical Petri net, this paper proposed a grid scheduling model based on hierarchical scheduling model. This model can ensure that the various elements of the loose coupling between the scheduling, to facilitate data resources deployment in grid environment; in addition, this paper proposed thought of the variable structure Petri network, through this technology can dynamic adjust work modeling and resource allocation, and to support the mission of exception handling; finally, to verify the rationality of the scheduling algorithm, and analyzes the performance and the efficiency of resource allocation algorithm.

Nonlinear aerostatic stability analysis of Hutong cable-stayed rail-cum-road bridge

Man Xu,Weiwei Guo,He Xia,Kebing Li 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.23 No.6

To investigate the nonlinear aerostatic stability of the Hutong cable-stayed rail-cum-road bridge with ultra-kilometer main span, a FEM bridge model is established. The tri-component wind loads and geometric nonlinearity are taken into consideration and discussed for the influence of nonlinear parameters and factors on bridge resistant capacity of aerostatic instability. The results show that the effect of initial wind attack-angle is significant for the aerostatic stability analysis of the bridge. The geometric nonlinearities of the bridge are of considerable importance in the analysis, especially the effect of cable sag. The instable mechanism of the Hutong Bridge with a steel truss girder is the spatial combination of vertical bending and torsion with large lateral bending displacement. The design wind velocity is much lower than the static instability wind velocity, and the structural aerostatic resistance capacity can meet the requirement.