Acoustic Radiation and Dynamic Study of a Steel Beam Damped with Viscoelastic Material

Quanmin Liu,Xiaozhen Li,Peipei Xu,Linya Liu,Yun-Lai Zhou 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.7

Steel structures subject to dynamic loads are prior to generate excessive vibration and noise. Viscoelastic treatment is an effective measure to mitigate the vibration and noise from thin-walled structures in a broad frequency range. H-shaped steel beams are widely used in civil engineering. So an experiment system is established and a series of impact hammer tests are conducted to assess the modal parameters, dynamic response and acoustic behaviour of an H-shaped steel beam coated with various viscoelastic treatments. Firstly, the spectra of the velocity response and acoustic radiation of the bare beam are analysed based on the tested data. Secondly, the resonance frequencies and modal loss factors of the beam with various viscoelastic treatments derived from the frequency response function are compared. Finally, the effect of the layout and thickness of viscoelastic patches on the mitigation of vibration and noise is discussed experimentally. It is shown that the modal loss factor of the first mode increases from 0.012 to 0.191 when the web is treated with 5 mm thick constrained layer damping (CLD). The viscoelastic patches on the web of the H-shaped beam are more effective to control the vibration and noise of the beam than the patches on the flanges. The viscoelastic treatment has distinct effect on the reduction of structural vibration and noise owing to the different dominant frequencies of vibration and noise as well as the frequency-dependent radiation efficiency. The normal velocity level of the H-shaped beam with an 8 mmthick web can be reduced by more than 10 dB and the sound pressure level around the beam about 8 dB when the web is partially covered with the constrained layer damping composed of 2.0 mm thick damping layer and 3.0 mm thick constraining layer.

The Relationship Between Curiosity and Development of Middle-aged Teachers in Normal Colleges

( Quanmin Liu ) 현대영미어문학회 2018 현대영미어문학회 추계학술대회 발표논문집 Vol.2018 No.-

Prediction of vibration and noise from steel/composite bridges based on receptance and statistical energy analysis

Quanmin Liu,Linya Liu,Huapeng Chen,Yunlai Zhou,Xiaoyan Lei 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.3

The noise from the elevated lines of rail transit has become a growing problem. This paper presents a new method for the rapid prediction of the structure-borne noise from steel or composite bridges, based on the receptance and Statistical Energy Analysis (SEA), which is essential to the study of the generation mechanism and the design of a low-noise bridge. First, the vertical track-bridge coupled vibration equations in the frequency domain are constructed by simplifying the rail and the bridge as an infinite Timoshenko beam and a finite Euler-Bernoulli beam respectively. Second, all wheel/rail forces acting upon the track are computed by taking a moving wheel-rail roughness spectrum as the excitation to the train-track-bridge system. The displacements of rail and bridge are obtained by substituting wheel/rail forces into the track-bridge coupled vibration equations, and all spring forces on the bridge are calculated by multiplying the stiffness by the deformation of each spring. Then, the input power to the bridge in the SEA model is derived from spring forces and the bridge receptance. The vibration response of the bridge is derived from the solution to the power balance equations of the bridge, and then the structure-borne noise from the bridge is obtained. Finally, a tri-span continuous steel-concrete composite bridge is taken as a numerical example, and the theoretical calculations in terms of the vibration and noise induced by a passing train agree well with the field measurements, verifying the method. The influence of various factors on wheel/rail and spring forces is investigated to simplify the train-track-bridge interaction calculation for predicting the vibration and noise from steel or composite bridges.

The CREG1-FBXO27-LAMP2 axis alleviates diabetic cardiomyopathy by promoting autophagy in cardiomyocytes

Liu Dan,Xing Ruinan,Zhang Quanyu,Tian Xiaoxiang,Qi Yanping,Song Haixu,Liu Yanxia,Yu Haibo,Zhang Xiaolin,Jing Quanmin,Yan Chenghui,Han Yaling 생화학분자생물학회 2023 Experimental and molecular medicine Vol.55 No.-

Autophagy plays an important role in the development of diabetic cardiomyopathy. Cellular repressor of E1A-stimulated genes 1 (CREG1) is an important myocardial protective factor. The aim of this study was to investigate the effects and mechanisms of CREG1 in diabetic cardiomyopathy. Male C57BL/6 J mice, Creg1 transgenic mice and cardiac-specific knockout mice were used to establish a type 2 diabetes model. Small animal ultrasound, Masson’s staining and western blotting were used to evaluate cardiac function, myocardial fibrosis and autophagy. Neonatal mouse cardiomyocytes (NMCMs) were stimulated with palmitate, and the effects of CREG1 on NMCMs autophagy were examined. CREG1 deficiency exacerbated cardiac dysfunction, cardiac hypertrophy and fibrosis in mice with diabetic cardiomyopathy, which was accompanied by exacerbated autophagy dysfunction. CREG1 overexpression improved cardiac function and ameliorated cardiac hypertrophy and fibrosis in diabetic cardiomyopathy by improving autophagy. CREG1 protein expression was decreased in palmitate-induced NMCMs. CREG1 knockdown exacerbated cardiomyocyte hypertrophy and inhibited autophagy. CREG1 overexpression inhibited cardiomyocyte hypertrophy and improved autophagy. LAMP2 overexpression reversed the effect of CREG1 knockdown on palmitate-induced inhibition of cardiomyocyte autophagy. CREG1 inhibited LAMP2 protein degradation by inhibiting the protein expression of F-box protein 27 (FBXO27). Our findings indicate new roles of CREG1 in the development of diabetic cardiomyopathy.

Study on vibration energy characteristics of vehicle-track-viaduct coupling system considering partial contact loss beneath track slab

Linya Liu,Zhiyuan Zuo,Qinyue Zhou,Jialiang Qin,Quanmin Liu 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.75 No.4

CA mortar layer disengagement will give rise to the overall structural changes of the track and variation in the vibration form of the ballastless track. By establishing a vehicle-track-viaduct coupling analysis and calculation model, it is possible to analyze the CRTS-I type track structure vibration response while the track slab is disengaging with the power flow evaluation method, to compare the two disengaging types, namely partial contact loss at one edge beneath track slab and partial contact loss at midpoint beneath track slab. It can also study how the length of disengaging influences the track structures vibration power. It is showed that when the partial contact loss beneath track slab, and the relative vibration energy level between the rail and the track slab increases significantly within [10, 200]Hz with the same disengaging length, the partial contact loss at one edge beneath track slab has more prominent influence on the vibration power than the partial contact loss at midpoint beneath track slab. With the increase of disengaging length, the relative vibration energy level of the track slab grows sharply, but it will change significantly when it reaches 1.56 m. Little effect will be caused by the relative vibration energy level of the viaduct. The partial contact loss beneath the track slab will cause more power distribution and transmission between the trail and track slab, and will then affect the service life of the rail and track slab.

Removal of minor concentration of H2S on MDEA-modified SBA-15 for gas purification

Quanmin Xue,Yingshu Liu 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.1

A promising adsorbent for H2S removal of minor concentration for gas purification was prepared by synthesizing and modifying the mesoporous molecular silica of SBA-15 with methyl-diethyl-amine (MDEA). Removal performance of minor concentration of H2S on the adsorbent was experimentally studied in a dynamic setup. The adsorbents showed good performance in removing H2S from gas steams. The loaded amines did not change the ordered structure of SBA-15, but enhanced its removing H2S. The adsorbents were characterized by X-ray powder diffraction (XRD) and N2 adsorption/desorption. Effect of the R (the loading ratio) of MDEA, effect of initial H2S concentration and effect of moisture on removal performance of H2S were studied respectively. With increase of the R of MDEA, the H2S removal performance of the adsorbent was improved obviously. When R of MDEA was 0.6, the removal performance was optimum. Initial H2S concentration had a large effect on the removal performance. Both breakthrough capacity and saturation capacity increased as the initial H2S concentration increased. In the presence of moisture, the experimental results showed the improvement in the removal performance of H2S. In addition, not only was the adsorbent regenerable by purging with the purified gas, but also the removal performance was stable in removal adsorption cycles.