Influence of some key factors on material damping of steel beams

Yuanfeng Wang,Yuhua Pan,Jie Wen,Li Su,Shengqi Mei 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.3

Material damping affects the dynamic behaviors of engineering structures considerably, but up to till now little research is maintained on influence factors of material damping. Based on the damping-stress function of steel, the material damping of steel beams is obtained by calculating the stress distribution of the beams with an analytical method. Some key influence factors of the material damping, such as boundary condition, amplitude and frequency of excitation, load position as well as the cross-sectional dimension of a steel beam are analyzed respectively. The calculated results show that even in elastic scope, material damping does not remain constant but varies with these influence factors. Although boundary condition affects material damping to some extent, such influence can be neglected when the maximum stress amplitude of the beam is less than the fatigue limit of steel. Exciting frequency, load position and cross-section dimension have great effects on the material damping of the beam which maintain the similar changing trend under different boundary conditions respectively.

Influence of some key factors on material damping of steel beams

Wang, Yuanfeng,Pan, Yuhua,Wen, Jie,Su, Li,Mei, Shengqi Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.3

Material damping affects the dynamic behaviors of engineering structures considerably, but up to till now little research is maintained on influence factors of material damping. Based on the damping-stress function of steel, the material damping of steel beams is obtained by calculating the stress distribution of the beams with an analytical method. Some key influence factors of the material damping, such as boundary condition, amplitude and frequency of excitation, load position as well as the cross-sectional dimension of a steel beam are analyzed respectively. The calculated results show that even in elastic scope, material damping does not remain constant but varies with these influence factors. Although boundary condition affects material damping to some extent, such influence can be neglected when the maximum stress amplitude of the beam is less than the fatigue limit of steel. Exciting frequency, load position and cross-section dimension have great effects on the material damping of the beam which maintain the similar changing trend under different boundary conditions respectively.

Omi inhibition ameliorates neuron apoptosis and neurological deficit after subarachnoid hemorrhage in rats

Du Yuanfeng,Yang Dingbo,Dong Xiaoqiao,Du Quan,Wang Ding,Shen Yongfeng,Yu Wenhua 한국유전학회 2021 Genes & Genomics Vol.43 No.12

Background Subarachnoid hemorrhage (SAH) is a severe neurological emergency, resulting in cognitive impairments and threatening human's health. Currently, SAH has no efective treatment. It is urgent to search for an efective therapy for SAH. Objective To explore the expression of Omi protein after subarachnoid hemorrhage in rats. Methods SAH rat model was established by injecting blood into the prechiasmatic cistern. Neurological defcit was assessed by detecting neurological defcit scores and brain tissue water contents. Apoptotic cells were evaluated by TUNEL staining and IHC staining. Omi and Cleaved caspase 3 expressions in nerve cells were determined by double staining using IF. Apoptosis-related proteins were measured by Western blotting assay. Results SAH rat model was successfully established, showing more apoptotic cells and high neurological defcit scores in SAH rat. In SAH rat model, Omi expression in nerve cells was elevated and the upregulation of Omi mainly occurred in cytoplasm, accompanied by the degradation of XIAP and the increased cleaved caspase 3/9 and cleaved PARP. Once treated with UCF-101, a specifc inhibitor of Omi, the increased cell apoptosis, left/right brain moisture contents and neurological defcits were notably reversed in SAH rat brain. Of note, SAH-induced the increases of apoptosis-related protein in nerve cells were also rescued by the administration of UCF-101. Conclusions UCF-101-mediated Omi inhibition decreased the degradation of XIAP and subsequently inhibited the activation of apoptosis-related proteins, decreased nerve cell apoptosis, leading to the improvement on early brain injury in SAH rat. UCF-101-based Omi inhibition may be used to treat SAH with great potential application.

Seismic analysis of bridges based on stress-dependent damping

Li Su,Yuanfeng Wang,Pengfei Li,Shengqi Mei,Kun Guo 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.3

Damping value has considerable influence on the dynamic and seismic behaviors of bridges. However, currently the constant damping ratios that are prescribed by most bridge seismic design codes can’t truly represent the complicated damping character of actual structures. In this paper, a cyclic loading experiment was conducted to study the effect of stress amplitude on material damping of concrete to present an analyzing model of the material damping of concrete. Furthermore, based on the fundamental damping of structure measured under ambient vibration, combined with the presented stress-dependent material damping concrete, the seismic response of a bridge pier was calculated. Comparison between the calculated and experiment results verified the validity of the presented damping model. Finally, a modified design and analysis method for bridge was proposed based on stress-dependent damping theory, and a continuous rigid frame bridge was selected as the example to calculate the actual damping values and the dynamic response of the bridge under different earthquake intensities. The calculation results indicated that using the constant damping given by the Chinese seismic design code of bridges would overestimate the energy dissipation capacity of the bridge.

Experimental study and modelling of CFRP-confined damaged and undamaged square RC columns under cyclic loading

Li Su,Xiaoran Li,Yuanfeng Wang 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.21 No.2

While the cyclic behaviour of fiber-reinforced polymer (FRP)-confined columns is studied rather extensively, the cyclic response especially the energy dissipation of FRP-confined damaged and undamaged square RC columns is not yet fully understood. In this paper, an experimental and numerical investigation was conducted to study the cyclic behavior of two different types of Carbon FRP (CFRP)-confined square RC columns: strengthened and repaired. The main variables investigated are initial damage, confinement of CFRP, longitudinal steel reinforcement ratio. The experimental results show that lower initial damage, added confinement with CFRP and longitudinal reinforcement enhance the ductility, energy dissipation capacity and strength of the columns, decrease the stiffness and strength degradation rates of all CFRP-confined square RC columns. Two hysteretic constitutive models were developed for confined damaged and undamaged concrete and cast into the non-linear beam-column fiber-based models in the software Open System for Earthquake Engineering Simulation (OpenSees) to analyze the cyclic behavior of CFRP-confined damaged and undamaged columns. The results of the numerical models are in good agreement with the experiments.

A Multicast Routing Algorithm Based on Prior Objective Nodes

Weijun Yang,Xiaodong Wang,Yuanfeng Chen 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.10

The minimum Steiner tree problem is an NP-complete problem in multicast routing algorithms. In this paper, an improved algorithm called the prior nodes minimum cost path heuristic (PNMPH) algorithm is presented according to the shortage of the minimum cost path heuristic (MPH) algorithm, in which some paths that pass through prior destination nodes are selected first. It partly shares links in the network and decreases the cost of the multicast routing tree. It is also closer to the optimal solution with the time complexity O(n3). The simulation results on the existing networks show that the cost of the PNMPH algorithm is lower than that of the MPH algorithm in the case of more than 90%.

Application of Acoustical Method to Characterize Nonwoven Material

Tao Yang,Xiaoman Xiong,Yuanfeng Wang,Rajesh Mishra,Michal Petrů,Jiří Militký 한국섬유공학회 2021 Fibers and polymers Vol.22 No.3

Some structural parameters, such as tortuosity, viscous and thermal characteristic lengths, are difficult to obtainthrough direct measurements. Existing indirect methods, i.e. acoustical method, make it possible to estimate theseparameters. This paper presents an application of acoustical inversion methods for estimating structural parameters ofpolyester nonwoven materials. A four-microphone impedance tube was used to measure sound reflection and transmissioncoefficients. The inversion methods used in this research are least square and Bayesian approaches. The least square methodwas achieved via Nelder-Mead algorithm. The Bayesian inversion process was conducted with Metropolis-Hastingsalgorithm and maximum a posteriori. Inversed parameters from two methods as well as front and back sides of nonwovenfabric were compared. Moreover, inversed porosity and airflow resistivity were compared with measured values. The resultsshow that the least square and Bayesian methods has a good agreement. Estimated parameters from Bayesian method wereselected for further analysis. A sizable differences on thermal characteristic length were found by comparing the values fromtwo sides, while the differences are relatively small for other parameters. It is also found that the inversed porosity, tortuosityare reasonable. The results suggest that the acoustical inversion methods can be used to accurately characterize polyesterfibrous materials.

A comparison of volatile fractions obtained from Lonicera macranthoides via different extraction processes: ultrasound, microwave, Soxhlet extraction, hydrodistillation, and cold maceration

Chun Wu,Feng Wang,Jiang Liu,Yuanfeng Zou,Xingfu Chen 한국한의학연구원 2015 Integrative Medicine Research Vol.4 No.3

Background: Hydrodistillation has been traditionally used to extract volatile fraction in traditional Chinese medicine. However, with the development of Soxhlet extraction (SE), microwave (MW), ultrasound (US), and cold maceration (CM), hydrodistillation (HD) is being replaced to meet some practical requirements. In this study, we investigated the effect of the five methods on the volatile fraction extract of Lonicera macranthoides. Methods: Volatile fraction from the flower buds of Lonicera macranthoides was obtained by using different extraction methods, HD, SE, MW, US, and CM. The compositions of volatile fraction were analyzed by gas chromatography–mass spectrometric and further compared among extraction methods. Results: Extracts obtained by the five methods reveal the qualitative and quantitative diversity in their compositions, especially for the low-content compositions. According to the results, SE shows the great value in the research where the high molecular-mass compound is of primary interest, and MW offers a way for the isolation of specific compound like octadecadienoic acid and hexadecanoic acid. HD, US, and CM have the advantage over SE and MW for the integrity of the constituents, whereas the phenomenon of compound degradation seems not so serious in solvent extraction methods such as US or CM as HD. Additionally, US and CM show superiority over time or material saving and diversity of the constituent. Conclusion: HD is still the best choice for the pure volatile fraction without organic solvent pollution. However, when it comes to some specifically actual demands, it can be replaced by the four methods for the volatile fraction extraction process, especially for production of certain compound groups.

Energy Management Strategy for Hybrid Energy Storage System based on Model Predictive Control

Shen Yongpeng,Li Yuanfeng,Liu Dongqi,Wang Yanfeng,Sun Jianbin,Sun Songnan 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.4

Electric vehicle (EV) is developed because of its environmental friendliness, energy-saving and high efficiency. For improving the performance of the energy storage system of EV, this paper proposes an energy management strategy (EMS) based model predictive control (MPC) for the battery/supercapacitor hybrid energy storage system (HESS), which takes stabilizing the DC bus voltage and improving the efficiency of the system as two major optimization goals. In addition, an enumeration algorithm is presented to solve the optimization function. The experimental results show the performance of the proposed EMS which is able to enhance the overall instantaneous power and prevent the battery from overloading. Meanwhile, compared with the results of a single battery storage system, the maximum amplitude of the battery current in the HESS is reduced by 40.81% and whole system energy loss is reduced by 24.13% with the proposed power management strategy.