Fluid-Structure Interaction Simulation of Flexible Supersonic Parachute Breathing Motion

MA Yongliang,LI Tao,WU Chui-Jie 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.10

In this paper, we propose a robust computational method for the coupled simulations that contain fluid-structure interaction between a high speed compressible flow and a highly flexible membrane structure. The governing equation used to model the air flow are the three-dimensional compressible Euler equations. To optimize computational efficiency, the fluid governing equations are discretized using a Cartesian adaptive mesh refinement (AMR) approach. Different levels of refinement are used in different regions of the domain depending on resolution needs. The canopy fabric of the parachute structure is represented by a triangulated surface mesh. The deformation process of the canopy and suspension lines and risers are modeled by the mass-spring system. The fluid?structure interaction (FSI) is modeled using a loosely coupled approach. This interaction is modeled only around the interface boundary using a variant of the ghost-fluid method. Several simulations are carried out at different Mach numbers. Comparisons of drag coefficient, breathing frequency and their dependence on Mach number are discussed. These simulations reproduce the large canopy-area unsymmetrical oscillations that are usually observed in these supersonic parachute systems.

A Facile One-Pot Method for Co3O4/Graphene Composite as Efficient Electrode Materials for Supercapacitors

Yongliang Wang,Rongxin Ma,Lizhu Liu,Zhanchun Xu,Fenghui Li 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.8

As one of the electrode materials for supercapacitor, Co3O4/graphene composite was mainly synthesized via two-steps method. Here, a facile one-pot method was used for Co3O4/graphene composite, and the performances of one-pot-synthesized Co3O4/graphene composite were carefully investigated. Liquid-phase exfoliation was used for graphene and the D-band/G-band ratio of liquid-phase exfoliated graphene was only 0.094, which indicated that the graphene had low defect density and enhanced electrical conductivity. Morphologies investigation of Co3O4/graphene composites indicated that Co3O4 nanoparticles with mean diameter of 14 nm were uniformly anchored on graphene sheets. The facile one-pot method associated with liquid-phase exfoliated graphene induced Co3O4/graphene composite with enhanced specific capacitance of 392 F · g -1 at a current density of 1 A · g -1. The Co3O4/graphene composite also expressed relatively small internal resistance and diffusion resistance (0.36 Ω and 0.45 Ω, respectively). Moreover, the synthesized Co3O4/graphene composite yielded excellent rate performances with only 9.5% capacitance loss when current density was increased by a factor of 10.

Study on the local damage of SFRC with different fraction under contact blast loading

Yongliang Zhang,Kai Zhao,Yongchi Li,Jincai Gu,Zhongbao Ye,Jian Ma 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.1

The steel fiber reinforced concrete (SFRC) shows better performance under dynamic loading than conventional concrete in virtue of its good ductility. In this paper, a series of quasi-static experiments were carried out on the SFRC with volume fractions from 0 to 6%. The compressive strength increases by 38% while the tension strength increases by 106% when the fraction is 6.0%. The contact explosion tests were also performed on the Ф40×6 cm circular SFRC slabs of different volume fractions with 20 g RDX charges placed on their surfaces. The volume of spalling pit decreases rapidly with the increase of steel fiber fraction with a decline of 80% when the fraction is 6%, which is same as the crack density. Based on the experimental results, the fitting formulae are given, which can be used to predict individually the change tendencies of the blast crater volume, the spalling pit volume and the crack density in slabs with the increase of the steel fiber fraction. The new formulae of the thickness of damage region are established, whose predictions agree well with our test results and others. This is of great practical significance for experimental investigations and engineering applications.

Exploiting Multi-Hop Relaying to Overcome Blockage in Directional mmWave Small Cells

Yong Niu,Chuhan Gao,Yongliang Ma,Li Su,Depeng Jin 한국통신학회 2016 Journal of communications and networks Vol.18 No.3

With vast amounts of spectrum available in themillimeter wave (mmWave) band, small cells at mmWave frequenciesdensely deployed underlying the conventional homogeneousmacrocell network have gained considerable interest fromacademia, industry, and standards bodies. Due to high propagationloss at higher frequencies, mmWave communications are inherentlydirectional, and concurrent transmissions (spatial reuse)under low inter-link interference can be enabled to significantlyimprove network capacity. On the other hand, mmWave linksare easily blocked by obstacles such as human body and furniture. In this paper, we develop a multi-hop relaying transmission(MHRT) scheme to steer blocked flows around obstacles by establishingmulti-hop relay paths. In MHRT, a relay path selectionalgorithm is proposed to establish relay paths for blocked flowsfor better use of concurrent transmissions. After relay path selection,we use a multi-hop transmission scheduling algorithm to computenear-optimal schedules by fully exploiting the spatial reuse. Through extensive simulations under various traffic patterns andchannel conditions, we demonstrate MHRT achieves superior performancein terms of network throughput and connection robustnesscompared with other existing protocols, especially under seriousblockage conditions. The performance ofMHRT with differenthop limitations is also simulated and analyzed for a better choiceof the maximum hop number in practice.

Association between Metabolically Healthy Status and Risk of Gastrointestinal Cancer

Haozhe Cui,Fei Tian,Yongliang Chen,Xiangming Ma 대한암학회 2024 Cancer Research and Treatment Vol.56 No.1

Purpose Although obesity is associated with numerous diseases, the risks of disease may depend on metabolically healthy status. Nevertheless, it is unclear to whether metabolically healthy status affects risk of gastrointestinal (GI) cancer in general Chinese population.Materials and Methods A total of 114,995 participants who met the criteria were included from the Kailuan Study. The study participants were divided into four groups according to body mass index (BMI)/waist circumference (WC) and metabolic status. Incident of GI cancer (esophageal cancer, gastric cancer, liver cancer, biliary cancer, pancreatic cancer, and colorectal cancer) during 2006-2020 were confirmed by review of medical records. The Cox proportional hazard regression models were used to assess the association metabolically healthy status with the risk of GI cancer by calculating the hazard ratios (HR) and 95% confidence interval (CI).Results During a mean 13.76 years of follow-up, we documented 2,311 GI cancers. Multivariate Cox regression analysis showed that compared with the metabolically healthy normal-weight group, metabolically healthy obese (MHO) participants demonstrated an increased risk of developing GI cancer (HR, 1.54; 95% CI, 1.11 to 2.13) by BMI categories. However, such associations were not found for WC category. These associations were moderated by age, sex, and anatomical site of the tumor. Individuals with metabolic unhealthy normal-weight or metabolic unhealthy obesity phenotype also have an increased risk of GI cancer.Conclusion MHO phenotype was associated with increased risk of GI cancer. Moreover, individuals who complicated by metabolic unhealthy status have an increased risk of developing GI cancer. Hence, clinicians should consider the risk of incident GI cancer in people with abnormal metabolically healthy status and counsel them about metabolic fitness and weight control.

Persulfate Wet Oxidation Method for the Determination of Total Phosphorus in Atmospheric Aerosols and Its Application for a Year-round Observation in Beijing

Tomoaki Okuda,Yuma Gunji,Kebin He,Yongliang Ma 한국대기환경학회 2013 Asian Journal of Atmospheric Environment (AJAE) Vol.7 No.3

Measurement of the phosphorus concentration in aerosols in Beijing, which was a representative East Asian mega-city, was carried out. The optimum procedure for analyzing phosphorus in aerosols was found in this study. Recovery of phosphorus in environmental samples through the improved method was almost 100%. The concentration of phosphorus in TSP was 145±47 ng/m3, with a seasonal variation showing high concentrations in winter and low concentrations in summer. The concentrations of phosphorus in PM2.5 accounted for 35±6% of those in TSP, with no seasonal variations. The major source of phosphorus in aerosols in Beijing was soil dust,and additional sources of phosphorus in fine particles could be coal combustion and biomass burning.

1-Aminocyclopropane-1-Carboxylate Deaminase from Pseudomonas stutzeri A1501 Facilitates the Growth of Rice in the Presence of Salt or Heavy Metals

( Yunlei Han ),( Rui Wang ),( Zhirong Yang ),( Yuhua Zhan ),( Yao Ma ),( Shuzhen Ping ),( Liwen Zhang ),( Min Lin ),( Yongliang Yan ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.7

1-Aminocyclopropane-1-carboxylate (ACC) deaminase, which is encoded by some bacteria, can reduce the amount of ethylene, a root elongation inhibitor, and stimulate the growth of plants under various environmental stresses. The presence of ACC deaminase activity and the regulation of ACC in several rhizospheric bacteria have been reported. The nitrogen-fixing Pseudomonas stutzeri A1501 is capable of endophytic association with rice plants and promotes the growth of rice. However, the functional identification of ACC deaminase has not been performed. In this study, the proposed effect of ACC deaminase in P. stutzeri A1501 was investigated. Genome mining showed that P. stutzeri A1501 carries a single gene encodingACC deaminase, designated acdS. The acdS mutant was devoid of ACC deaminase activity and was less resistant to NaCl and NiCl2 compared with the wild-type. Furthermore, inactivation of acdS greatly impaired its nitrogenase activity under salt stress conditions. It was also observed that mutation of the acdS gene led to loss of the ability to promote the growth of rice under salt or heavy metal stress. Taken together, this study illustrates the essential role of ACC deaminase, not only in enhancing the salt or heavy metal tolerance of bacteria but also in improving the growth of plants, and provides a theoretical basis for studying the interaction between plant growth-promoting rhizobacteria and plants.