Failure Mechanism of Single-layer Saddle-curve Reticulated Shells with Material Damage Accumulation Considered under Severe Earthquake

Zhiwei Yu,Xudong Zhi,Feng Fan,Chen Lu 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.1

This paper presents the study on failure mechanism of single-layer saddle-curve reticulated shells subjected to severe earthquake. Failure mode of single-layer saddle-curve reticulated shells is illustrated with the consideration of material damage accumulation. The effects of different parameters on failure characteristics of single-layer saddle-curve reticulated shells are discussed. The influence of substructure upon failure behaviors of single-layer saddle-curve reticulated shells is particularly investigated. It is observed that dynamic strength failure is the failure mode of single-layer saddle-curve reticulated shells. The substructure has great influence on failure characteristics of single-layer saddle-curve reticulated shells subjected to the severe earthquake.

Smart Anti-jamming Mobile Communication for Cloud and Edge-Aided UAV Network

( Zhiwei Li ),( Yu Lu ),( Zengguang Wang ),( Wenxin Qiao ),( Donghao Zhao ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.12

The Unmanned Aerial Vehicles (UAV) networks consisting of low-cost UAVs are very vulnerable to smart jammers that can choose their jamming policies based on the ongoing communication policies accordingly. In this article, we propose a novel cloud and edge-aided mobile communication scheme for low-cost UAV network against smart jamming. The challenge of this problem is to design a communication scheme that not only meets the requirements of defending against smart jamming attack, but also can be deployed on low-cost UAV platforms. In addition, related studies neglect the problem of decision-making algorithm failure caused by intermittent ground-to-air communication. In this scheme, we use the policy network deployed on the cloud and edge servers to generate an emergency policy tables, and regularly update the generated policy table to the UAVs to solve the decision-making problem when communications are interrupted. In the operation of this communication scheme, UAVs need to offload massive computing tasks to the cloud or the edge servers. In order to prevent these computing tasks from being offloaded to a single computing resource, we deployed a lightweight game algorithm to ensure that the three types of computing resources, namely local, edge and cloud, can maximize their effectiveness. The simulation results show that our communication scheme has only a small decrease in the SINR of UAVs network in the case of momentary communication interruption, and the SINR performance of our algorithm is higher than that of the original Q-learning algorithm.

Extraction of quasi-static component from vehicle-induced dynamic response using improved variational mode decomposition

Zhiwei Chen,Long Zhao,Yigui Zhou,Wen-Yu He,Wei-Xin Ren 국제구조공학회 2023 Smart Structures and Systems, An International Jou Vol.31 No.2

The quasi-static component of the moving vehicle-induced dynamic response is promising in damage detection as it is sensitive to bridge damage but insensitive to environmental changes. However, accurate extraction of quasi-static component from the dynamic response is challenging especially when the vehicle velocity is high. This paper proposes an adaptive quasistatic component extraction method based on the modified variational mode decomposition (VMD) algorithm. Firstly the analytical solutions of the frequency components caused by road surface roughness, high-frequency dynamic components controlled by bridge natural frequency and quasi-static components in the vehicle-induced bridge response are derived. Then a modified VMD algorithm based on particle swarm algorithm (PSO) and mutual information entropy (MIE) criterion is proposed to adaptively extract the quasi-static components from the vehicle-induced bridge dynamic response. Numerical simulations and real bridge tests are conducted to demonstrate the feasibility of the proposed extraction method. The results indicate that the improved VMD algorithm could extract the quasi-static component of the vehicle-induced bridge dynamic response with high accuracy in the presence of the road surface roughness and measurement noise.

Serum leptin, adiponectin and endometrial cancer risk in Chinese women

Yu Ma,Zhiwei Liu,Yan Zhang,Bingjian Lu 대한부인종양학회 2013 Journal of Gynecologic Oncology Vol.24 No.4

Objective: To investigate the relationship between serum concentrations of leptin or adiponectin, and endometrial carcinoma in Chinese women. Methods: We conducted a case-control study of a total of 516 Chinese women to detect the relationships between serum concentrations of leptin or adiponectin, and endometrial carcinoma in Chinese women. The study subject constituted 206 cases of endometrial cancer and 310 normal controls. Results: Patients with endometrial carcinoma had higher serum leptin concentrations than controls (28.8±2.2 ug/L vs. 19.8±1.4 ug/L; p<0.001). The adiponectin levels in patients were lower than in controls with borderline statistical significance (2,330.7±180.5 ug/L vs. 2,583.9±147.2 ug/L; p=0.078). Logistic regression analysis confirmed the associations between leptin or adiponectin, and endometrial carcinoma after adjustment for age, body mass index, fasting insulin, serum glucose, cholesterol, triglycerides, and high-density lipoprotein cholesterol (odds ratio for the top tertile vs. the bottom tertile: leptin 2.05; 95% confidence interval [CI], 1.28 to 3.29; p<0.001; adiponectin 0.52; 95% CI, 0.32 to 0.83; p<0.001). Conclusion: Increased leptin or decreased adiponectin levels are associated with endometrial carcinoma.

Dynamic changes of yak (Bos grunniens) gut microbiota during growth revealed by polymerase chain reaction-denaturing gradient gel electrophoresis and metagenomics

Yuanyang Nie,Zhiwei Zhou,Jiuqiang Guan,Baixue Xia,Xiaolin Luo,Yang Yang,Yu Fu,Qun Sun 아세아·태평양축산학회 2017 Animal Bioscience Vol.30 No.7

Objective: To understand the dynamic structure, function, and influence on nutrient metabolism in hosts, it was crucial to assess the genetic potential of gut microbial community in yaks of different ages. Methods: The denaturing gradient gel electrophoresis (DGGE) profiles and Illumina-based metagenomic sequencing on colon contents of 15 semi-domestic yaks were investigated. Unweighted pairwise grouping method with mathematical averages (UPGMA) clustering and principal component analysis (PCA) were used to analyze the DGGE fingerprint. The Illumina sequences were assembled, predicted to genes and functionally annotated, and then classified by querying protein sequences of the genes against the Kyoto encyclopedia of genes and genomes (KEGG) database. Results: Metagenomic sequencing showed that more than 85% of ribosomal RNA (rRNA) gene sequences belonged to the phylum Firmicutes and Bacteroidetes, indicating that the family Ruminococcaceae (46.5%), Rikenellaceae (11.3%), Lachnospiraceae (10.0%), and Bacteroidaceae (6.3%) were dominant gut microbes. Over 50% of non-rRNA gene sequences represented the metabolic pathways of amino acids (14.4%), proteins (12.3%), sugars (11.9%), nucleotides (6.8%), lipids (1.7%), xenobiotics (1.4%), coenzymes, and vitamins (3.6%). Gene functional classification showed that most of enzyme-coding genes were related to cellulose digestion and amino acids metabolic pathways. Conclusion: Yaks’ age had a substantial effect on gut microbial composition. Comparative metagenomics of gut microbiota in 0.5-, 1.5-, and 2.5-year-old yaks revealed that the abundance of the class Clostridia, Bacteroidia, and Lentisphaeria, as well as the phylum Firmicutes, Bacteroidetes, Lentisphaerae, Tenericutes, and Cyanobacteria, varied more greatly during yaks’ growth, especially in young animals (0.5 and 1.5 years old). Gut microbes, including Bacteroides, Clostridium, and Lentisphaeria, make a contribution to the energy metabolism and synthesis of amino acid, which are essential to the normal growth of yaks.

Preparation of Cobalt Ferrite Nanoparticle-Decorated Boron Nitride Nanosheet Flame Retardant and Its Flame Retardancy in Epoxy Resin

Qiaoran Zhang,Zhiwei Li,Xiaohong Li,Laigui Yu,Zhijun Zhang,Zhishen Wu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.5

Boron nitride nanosheet (BNNS) decorated with cobalt ferrite nanoparticle (CFN) to afford CFN-BNNS nanohybrid was prepared via a simple hydrothermal route and was well characterized. Subsequently, the as-prepared CFN-BNNS nanohybrid was incorporated into epoxy resin (EP) with the introduction of a weak rotary magnetic field to achieve order orientation, in order to reduce the fire risk and toxic hazards using enhanced shielding effect of BNNS upon combustion. Findings demonstrate that the CFN-BNNS nanohybrid is composed of CFN nanoparticle uniformly dispersed on BNNS surface. Thermal analysis and cone calorimeter data show that the CFN-BNNS nanofiller among EP matrix contributes to improving the char residues and mechanical properties of EP and reducing its fire risk as well as toxic hazards, especially the ordered one is advantageous over the disordered one in reducing the fire risk and toxic hazard. This is because, on the one hand, the orderly aligned BNNS as the physical barrier can more effectively prevent the transfer and diffusion of oxygen and heat. On the other hand, CFN can catalyze the degradation of EP to afford excessive chars on polymer surface; and it is also liable to decomposition during combustion, thereby generating ferrite species to promote EP degradation as well as cobalt species to enhance the oxidation of CO.

The genome of Bacillus aryabhattai T61 reveals its adaptation to Tibetan Plateau environment

Ping Wan,ZhiWei Yang,Yan Yan,Lei Zhang,MengYao Yu,Jian Wang,He Tang 한국유전학회 2016 Genes & Genomics Vol.38 No.3

Tibetan Plateau is called ‘the Roof of the World’. Organisms survive there have to adapt to the high altitude environment. By shotgun method, we sequenced the genome of Bacillus aryabhattai T61, which inhabits in the soil at the altitude of 4123 m in Shigatse, Tibetan. Further, we explored the genomic basis for its adaptations to the plateau environment. The results showed that B. aryabhattai T61 has evolved an array of ROS defense systems and sporulation system for adaptations to the stresses caused by the plateau strong ultraviolet radiation, extreme oxygen limitation and low temperature. Specifically, B. aryabhattai T61 encodes the ResE–ResD twocomponent to sense the oxygen limitation and regulates COX15 for aerobic and anaerobic respiration. The twocomponent system DesK–DesR, which regulates the gene Des initiating the biosynthesis of unsaturated fatty acids, along with 33 temperature-shock proteins contribute to low temperature adaptation. With the comparative analysis, we deduced the novel gene cbiY may be involved in cobalamin biosynthesis. We also found that B. aryabhattai T61 may have novel regulatory mechanisms for sporulation initiation. B. aryabhattai T61 is the first Tibetan strain with high quality genome sequenced. The genome provides a paradigm for understanding the adaptations to the plateau environment in Bacteria kingdom.

Failure Mechanism of Single-layer Steel Reticular Domes with Reinforced Concrete Substructure Subjected to Severe Earthquakes

Chen Lu,Zhiwei Yu,Shuiming Li,Dagang Lu,Jian Liu 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4

This paper performs the research on failure mechanism of single-layer steel reticulated domes with the reinforced concrete substructure subjected to sever earthquakes. Based on ABAQUS, this paper built user-defined material subroutines of the steel and the reinforced concrete, which took material non-linearity and the material damage accumulation into consideration. The failure mechanism of reticulated domes with reinforced concrete substructures under severe earthquakes is studied by the nonlinear dynamic response analysis. Three different failure modes of single-layer reticular domes with different sizes of reinforced concrete substructure are illustrated. Failure criterion is put forward to discriminate the failure modes and to estimate the critical load strength for single-layer reticular domes based on the structural damage theory. It has been found that reinforced concrete substructure has significant impact on the failure behaviors and the critical load of reticulated domes under seismic loads. It is essential to consider the influence of the reinforced concrete substructure upon the failure behaviors in the structural analysis and design process of reticular domes.

Biomass Chitosan-Induced Fe3O4 Functionalized Halloysite Nanotube Composites: Preparation, Characterization and Flame-Retardant Performance

Mengmeng Zhang,Yamin Cheng,Zhiwei Li,Xiaohong Li,Laigui Yu,Zhijun Zhang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.15 No.01

An inorganic–organic nanohybrid flame retardant, HNT@CS@Fe3O4, is prepared by Halloysite nanotubes (HNT) as nanotemplate, chitosan (CS) as char-forming agent and ferroferric oxide (Fe3O4) playing in a catalytic role, aiming to endow enhanced flame-retardant performance of its nanohybrid. Results show that HNT@CS@Fe3O4 nanohybrids have a corn-like structure and can significantly improve the flame retardancy and thermal stability of epoxy resin (EP). Especially, the initial thermal degradation temperature of EP/HNT@CS@Fe3O4 is significantly improved by 24 ℃ relative to pure EP, and the residual carbon yield under air atmosphere is 8.8 wt.%, which is significantly higher than other EP composites, indicating a higher thermal stability is offered by the as-prepared nanohybrid. The limiting oxygen index of EP/10HNT@CS@Fe3O4 is 31.3%, which is 10.2% higher than that of pure EP. Meanwhile, the HNT@CS@Fe3O4 nanofiller reduces the peak heat release rate, CO production and peak smoke production release of EP nanocomposite by 32.0%, 44.0% and 33.0% in a cone calorimeter test, respectively. This is because the HNT-based composite can form a three-dimensional network structure into the EP matrix to inhibit heat release and diffusion of flammable moieties upon burning of EP. In the meantime, the incorporated Fe3O4 nanoparticle can in situ catalyze the charring of CS and EP matrix on the surface of HNT during the combustion process, which also contributes to the significantly increased fire safety of EP.

Targeting the IL-1β/IL-1Ra pathways for the aggregation of human islet amyloid polypeptide in an ex vivo organ culture system of the intervertebral disc

Cao Yang,Xinghuo Wu,Zhiwei Liao,Kun Wang,Wenbin Hua,Xianzhe Liu,Yu Song,Yukun Zhang,Shuhua Yang 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

Intervertebral disc degeneration (IDD) is characterized by excessive apoptosis of nucleus pulposus (NP) cells and hyperactive extracellular matrix (ECM) catabolism. Our previous studies revealed the relationship between human islet amyloid polypeptide (hIAPP) and NP cell apoptosis. However, the role of hIAPP aggregates in IDD has not yet been investigated. This study aimed to determine whether the accumulation of hIAPP aggregates promotes IDD progression. The aggregation of hIAPP increased in human NP tissues during IDD. The deposition of hIAPP aggravated the compression-induced IDD that promoted NP cell apoptosis and ECM degradation via IL-1β/IL-1Ra signaling in an ex vivo rat disc model. Moreover, neutralizing IL-1β augmented the protective effects of hIAPP overexpression by decreasing hIAPP aggregation in human NP cells. These results suggest that the aggregation of hIAPP promotes NP cell apoptosis and ECM degradation ex vivo and in vitro by disrupting the balance of IL-1β/IL-1Ra signaling.