Practical countermeasures for the aerodynamic performance of long-span cable-stayed bridges with open decks

Zhou, Rui,Yang, Yongxin,Ge, Yaojun,Mendis, Priyan,Mohotti, Damith Techno-Press 2015 Wind and Structures, An International Journal (WAS Vol.21 No.2

Open decks are a widely used deck configuration in long-span cable-stayed bridges; however, incorporating aerodynamic countermeasures are advisable to achieve better aerodynamic performance than a bluff body deck alone. A sectional model of an open deck cable-stayed bridge with a main span of 400 m was selected to conduct a series of wind tunnel tests. The influences of five practical aerodynamic countermeasures on flutter and vortex-induced vibration (VIV) performance were investigated and are presented in this paper. The results show that an aerodynamic shape selection procedure can be used to evaluate the flutter stability of decks with respect to different terrain types and structural parameters. In addition, the VIV performance of $\prod$-shaped girders for driving comfortableness and safety requirements were evaluated. Among these aerodynamic countermeasures, apron boards and wind fairings can improve the aerodynamic performance to some extent, while horizontal guide plates with 5% of the total deck width show a significant influence on the flutter stability and VIV. A wind fairing with an angle of $55^{\circ}C$ showed the best overall control effect but led to more lock-in regions of VIV. The combination of vertical stabilisers and airflow-depressing boards was found to be superior to other countermeasures and effectively boosted aerodynamic performance; specifically, vertical stabilisers significantly contribute to improving flutter stability and suppressing vertical VIV, while airflow-depressing boards are helpful in reducing torsional VIV.

Aerodynamic performance evaluation of different cable-stayed bridges with composite decks

Rui Zhou,Yaojun Ge,Yongxin Yang,Yanliang Du,Lihai Zhang 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.5

The aerodynamic performance of long-span cable-stayed bridges is much dependent on its geometrical configuration and countermeasure strategies. In present study, the aerodynamic performance of three composite cable-stayed bridges with different tower configurations and passive aerodynamic countermeasure strategies is systematically investigated by conducting a series of wind tunnel tests in conjunction with theoretical analysis. The structural characteristics of three composite bridges were firstly introduced, and then their stationary aerodynamic performance and wind-vibration performance (i.e., flutter performance, VIV performance and buffeting responses) were analyzed, respectively. The results show that the bridge with three symmetric towers (i.e., Bridge I) has the lowest natural frequencies among the three bridges, while the bridge with two symmetric towers (i.e., Bridge II) has the highest natural frequencies. Furthermore, the Bridge II has better stationary aerodynamic performance compared to two other bridges due to its relatively large drag force and lift moment coefficients, and the improvement in stationary aerodynamic performance resulting from the application of different countermeasures is limited. In contrast, it demonstrates that the application of both downward vertical central stabilizers (UDVCS) and horizontal guide plates (HGP) could potentially significantly improve the flutter and vortex-induced vibration (VIV) performance of the bridge with two asymmetric towers (i.e., Bridge III), while the combination of vertical interquartile stabilizers (VIS) and airflowdepressing boards (ADB) has the capacity of improving the VIV performance of Bridge II.

Research on the Method for Periodic Estimation of the PN Sequence in the Lower SNR DS/SS Signals

Fan Zhou,Yongxin Feng,Xiaoyu Zhang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.10

The periodic estimation method of the PN sequence in DS Signal is researched. It is hard for traditional methods to estimate PN period of DS/SS accurately in the condition of low Signal-to-noise ratio. On the basis of the traditional spectrum reprocessing and the cepstrum method, a PN period estimation method which has integrated serial average with spectrum reprocessing and the cepstrum are put forward to solve this problem and meet the requirements of lower Signal-to-noise ratio. The simulation results show that, when the period of PN sequence is estimated accurately, the cepstrum method has better estimating performance than the spectrum reprocessing method, and the spectral estimation method has lower Signal-to-noise ratio tolerance after improvements.

Practical countermeasures for the aerodynamic performance of long-span cable-stayed bridges with open decks

Rui Zhou,Yongxin Yang,Yaojun Ge,Priyan Mendis,Damith Mohotti 한국풍공학회 2015 Wind and Structures, An International Journal (WAS Vol.21 No.2

Open decks are a widely used deck configuration in long-span cable-stayed bridges; however, incorporating aerodynamic countermeasures are advisable to achieve better aerodynamic performance than a bluff body deck alone. A sectional model of an open deck cable-stayed bridge with a main span of 400 m was selected to conduct a series of wind tunnel tests. The influences of five practical aerodynamic countermeasures on flutter and vortex-induced vibration (VIV) performance were investigated and are presented in this paper. The results show that an aerodynamic shape selection procedure can be used to evaluate the flutter stability of decks with respect to different terrain types and structural parameters. In addition, the VIV performance of Π-shaped girders for driving comfortableness and safety requirements were evaluated. Among these aerodynamic countermeasures, apron boards and wind fairings can improve the aerodynamic performance to some extent, while horizontal guide plates with 5% of the total deck width show a significant influence on the flutter stability and VIV. A wind fairing with an angle of 55° showed the best overall control effect but led to more lock-in regions of VIV. The combination of vertical stabilisers and airflow-depressing boards was found to be superior to other countermeasures and effectively boosted aerodynamic performance; specifically, vertical stabilisers significantly contribute to improving flutter stability and suppressing vertical VIV, while airflow-depressing boards are helpful in reducing torsional VIV

The Synergism of Human Lactobacillaceae and Inulin Decrease Hyperglycemia via Regulating the Composition of Gut Microbiota and Metabolic Profiles in db/db Mice

Li Peifan,Tong Tong,Wu Yusong,Zhou Xin,Zhang Michael,Liu Jia,She Yongxin,Li Zuming,Li Yongli 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.12

This study aimed to evaluate the effects of Limosilactobacillus fermentum and Lactiplantibacillus plantarum isolated from human feces coordinating with inulin on the composition of gut microbiota and metabolic profiles in db/db mice. These supplements were administered to db/db mice for 12 weeks. The results showed that the Lactobacillaceae coordinating with inulin group (LI) exhibited lower fasting blood glucose levels than the model control group (MC). Additionally, LI was found to enhance colon tissue and increase the levels of short-chain fatty acids. 16S rRNA sequencing revealed that the abundance of Corynebacterium and Proteus, which were significantly increased in the MC group compared with NC group, were significantly decreased by the treatment of LI that also restored the key genera of the Lachnospiraceae_NK4A136_group, Lachnoclostridium, Ruminococcus_ gnavus_group, Desulfovibrio, and Lachnospiraceae_UCG-006. Untargeted metabolomics analysis showed that lotaustralin, 5-hydroxyindoleacetic acid, and 13(S)-HpODE were increased while L-phenylalanine and L-tryptophan were decreased in the MC group compared with the NC group. However, the intervention of LI reversed the levels of these metabolites in the intestine. Correlation analysis revealed that Lachnoclostridium and Ruminococcus_gnavus_group were negatively correlated with 5-hydroxyindoleacetic acid and 13(S)-HpODE, but positively correlated with L-tryptophan. 13(S)-HpODE was involved in the "linoleic acid metabolism". L-tryptophan and 5-hydroxyindoleacetic acid were involved in "tryptophan metabolism" and "serotonergic synapse". These findings suggest that LI may alleviate type 2 diabetes symptoms by modulating the abundance of Ruminococcus_gnavus_group and Lachnoclostridium to regulate the pathways of "linoleic acid metabolism", "serotonergic synapse", and" tryptophan metabolism". Our results provide new insights into prevention and treatment of type 2 diabetes.

Solidification/stabilization of simulated cadmium-contaminated wastes with magnesium potassium phosphate cement

Ying Su,Jianming Yang,Debin Liu,Shucong Zhen,Naixi Lin,Yongxin Zhou 대한환경공학회 2016 Environmental Engineering Research Vol.21 No.1

Magnesium potassium phosphate cement (MKPC) is an effective agent for solidification/stabilization (S/S) technology. To further explore the mechanism of the S/S by MKPC, two kinds of Cd including Cd(NO₃)2 solution (L-Cd) and municipal solid waste incineration fly ash (MSWI FA) adsorbed Cd (S-Cd), were used to compare the effects of the form of heavy metal on S/S. The results showed that all the MKPC pastes had a high unconfined compressive strength (UCS) above 11 MPa. For L-Cd pastes, Cd leaching concentration increased with the increase of Cd content, and decreased with the increase of curing time. With the percentage of MSWI FA below 20%, S-Cd pastes exhibited similar Cd leaching concentrations as those of L-Cd pastes, while when the content of MSWI FA come up to 30%, the Cd leaching concentration increased significantly. To meet the standard GB5085.3-2007, the highest addition of S-Cd was 30% MSWI FA (6% Cd contained), with the Cd leaching concentration of 0.817 mg/L. The S/S of L-Cd is mainly due to chemical fixation, and the hydration compound of Cd was NaCdPO₄, while the S/S of S-Cd is due to physical encapsulation, which is dependent on the pore/crack size and porosity of the MKPC pastes.

Hot deformation behavior of CNTs/Al-Li composite prepared by powder metallurgy

Jia Lei,Liu Yang,Xing Zhiguo,He Gengchao,Lu Zhenlin,Zhou Yongxin 한국탄소학회 2022 Carbon Letters Vol.32 No.5

CNTs/Al-Li composite was first prepared by hot-pressed sintering from Al-Li alloy powder and CNTs solution, and then the hot compression tests were performed on MMS-100 thermal simulator at strain rate range of 0.01– 10 s−1, deformation temperature range of 350–500 °C, and total deformation amount of 60%. True stress–strain curves were plotted, and constitutive equation as well as hot processing maps were successfully confirmed based on Arrhenius constitutive model and Prasad instability criterion. Results show that CNTs/Al-Li composite have a very poor hot deformation ability and narrow processing region, which is strain rate range of 0.1–1 s−1 and deformation temperature range of 360–400 °C. Hot extrusion experiment was carried out and the processing parameters were selected according to the established hot processing map, and an improvement on strength and a good balance between strength and plasticity can be obtained, which is about 650 MPa for tensile strength and 9% for elongation.

Effects of Sulfur Introduction on the UV and the Visible Emission Properties of ZnO

Hongying Guo,Feihong Jiang,Run Yuan,Jun Zhang,Yuanping Sun,Yifan Liu,Yongxin Qiu,Taofei Zhou,Xionghui Zeng,Baoshun Zhang,Ke Xu,Hui Yang 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.4

Hexagonal ZnO particles have been synthesized by using the hydrothermal method with differentsulfur concentrations in the reaction solutions. Structural and optical characterizations have beenconducted to study the effects of the sulfur in the reaction solutions on the properties of thesynthesized ZnO in the ultraviolet (UV) and the visible (VIS) bands. The existance of sulfur inthe solutions can help to introduce compression strain along the a axis and an opposite trend forthe parameter c with strain inside the formed ZnO particles, which means the total strain in thesamples is presented along the c axis. The average size of the ZnO particles, as calculated fromSEM images, shows the same trend as the strain in the samples. The increasing incorporation ofsulfur causes an increase in the VIS luminescence band, which can be attributed to an increase inthe number of sulfur-induced defects.