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.

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.

A Novel 3-D Imaging Configuration Exploiting Synthetic Aperture Ladar

Liang Guo,Yinli Huang,Xiaozhen Li,Xiaodong Zeng,Yu Tang,Mengdao Xing 한국광학회 2017 Current Optics and Photonics Vol.1 No.6

Traditional three-dimensional (3-D) laser imaging systems are based on real aperture imaging technology,whose resolution decreases as the range increases. In this paper, we develop a novel 3-D imaging techniquebased on the synthetic aperture technology in which the imaging resolution is significantly improved anddoes not degrade with the increase of the range. We consider an imaging laser radar (ladar) system usingthe floodlight transmitting mode and multi-beam receiving mode. High 3-D imaging resolutions areachieved by matched filtering the linear frequency modulated (LFM) signals respectively in range, syntheticaperture along-track, and the real aperture across-track. In this paper, a novel 3-D imaging signal modelis given first. Because of the motion during the transmission of a sweep, the Doppler shift induced bythe continuous motion is taken into account. And then, a proper algorithm for the 3-D imaging geometryis given. Finally, simulation results validate the effectiveness of the proposed technique.

Contrast-enhanced ultrasonography-based renal blood perfusion in brain-dead donors predicts early graft function

Weiming He,Yuguang Xu,Chaoyang Gong,Xiaozhen Liu,Yuqiang Wu,Xi Xie,Jiazhen Chen,Yi Yu,Zhiyong Guo,Qiang Sun 대한초음파의학회 2023 ULTRASONOGRAPHY Vol.42 No.4

Purpose: The aim of this study was to quantify renal microcirculatory perfusion in braindead donors using contrast-enhanced ultrasonography (CEUS), and to establish an accurate, noninvasive, and convenient index for predicting delayed graft function (DGF) post-transplantation. Methods: In total, 90 brain-dead donor kidneys (training group, n=60; validation group, n=30) examined between August 2020 and November 2022 were recruited in this prospective study. CEUS was performed on the kidneys of brain-dead donors 24 hours before organ procurement and time-intensity curves were constructed. The main measures were arrival time, time to peak, and peak intensity of the kidney segmental arteries, cortex, and medulla. Recipients were divided into DGF and non-DGF groups according to early post-transplant graft function. The area under the receiver operating characteristic curve (AUC) was used to assess diagnostic performance. Results: The arrival time of the kidney segmental artery and cortex and the time interval between the time to peak of the segmental artery and cortex were identified as independent factors associated with DGF by multivariate stepwise regression analysis. A new index for the joint prediction model of three variables, the contrast-enhanced ultrasonography/Kidney Donor Profile index (CEUS-KDPI), was developed. CEUS-KDPI showed high accuracy for predicting DGF (training group: AUC, 0.91; sensitivity, 90.5%; specificity, 92.3%; validation group: AUC, 0.84; sensitivity, 75.0%; specificity, 92.3%). Conclusion: CEUS-KDPI accurately predicted DGF after kidney transplantation. CEUS may be a potential noninvasive tool for bedside examinations before organ procurement and may be used to predict early renal function after kidney transplants kidneys from donors after brain death.

Broad Activity against Porcine Bacterial Pathogens Displayed by Two Insect Antimicrobial Peptides Moricin and Cecropin B

Han Hu,Qigai He,Chunmei Wang,Xiaozhen Guo,Wentao Li,Yang Wang 한국분자세포생물학회 2013 Molecules and cells Vol.35 No.2

In response to infection, insects produce a variety of antimicrobial peptides (AMPs) to kill the invading patho-gens. To study their physicochemical properties and bioactivities for clinical and commercial use in the porcine industry, we chemically synthesized the mature peptides Bombyx mori moricin and Hyalophora cecropia cecropin B. In this paper, we described the antimicrobial activity of the two AMPs. Moricin exhibited antimicrobial activity on eight strains tested with minimal inhibitory concentration values (MICs) ranging between 8 and 128 g/ml, while cecropin B mainly showed antimicrobial activity against the Gram-negative strains with MICs ranging from 0.5 to 16 g/ml. Compared to the potent antimicrobial activity these two AMPs displayed against most of the bacterial pathogens tested, they exhibited limited hemolytic activity against porcine red blood cells. The activities of moricin and cecropin B against Haemophilus parasuis SH 0165 were studied in further detail. Transmission electron microscopy (TEM) of moricin and cecropin B treated H. parasuis SH 0165 indicated extensive damage to the membranes of the bacteria. Insights into the probable mechanism utilized by moricin and cecropin B to eliminate pathogens are also presented. The observations from this study are important for the future application of AMPs in the porcine industry.

Investigation of morphological changes of HPS membrane caused by cecropin B through scanning electron microscopy and atomic force microscopy

Han Hu,Changsheng Jiang,Binzhou Zhan,Nan Guo,Zhonghua Li,Xiaozhen Guo,Yang Wang,Binlei Liu,Qigai He 대한수의학회 2021 Journal of Veterinary Science Vol.22 No.5

Background: Antimicrobial peptides (AMPs) have been identified as promising compounds for consideration as novel antimicrobial agents. Objectives: This study analyzed the efficacy of cecropin B against Haemophilus parasuis isolates through scanning electron microscopy (SEM) and atomic force microscopy (AFM) experiments. Results: Cecropin B exhibited broad inhibition activity against 15 standard Haemophilus parasuis (HPS) strains and 5 of the clinical isolates had minimum inhibition concentrations (MICs) ranging from 2 to 16 μg/mL. Microelectrophoresis and hexadecane adsorption assays indicated that the more hydrophobic and the higher the isoelectric point (IEP) of the strain, the more sensitive it was to cecropin B. Through SEM, multiple blisters of various shapes and dents on the cell surface were observed. Protrusions and leakage were detected by AFM. Conclusions: Based on the results, cecropin B could inhibit HPS via a pore-forming mechanism by interacting with the cytoplasmic membrane of bacteria. Moreover, as cecropin B concentration increased, the bacteria membrane was more seriously damaged. Thus, cecropin B could be developed as an effective anti-HPS agent for use in clinical applications.