检索结果-内蒙古大学图书馆

Effect of temperature gradient on transient thermal creep of heated and stressed concrete in transient state tests

CONSTRUCTION AND BUILDING MATERIALS 2019年 222卷 839-851页

作者： Fan, Kunjie Li, Dawang Li, Long-yuan Wu, Jiayu Shenzhen Univ Guangdong Prov Key Lab Durabil Maine Civil Engn Shenzhen 518060 Peoples R China Univ Plymouth Sch Engn Plymouth PL4 8AA Devon England Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Inst Appl Mech Guangzhou 510632 Guangdong Peoples R China

The stress-strain constitutive relation of concrete subjected to thermomechanical loads is extremely complicated since its deformation relies on the sequences in which the heat and loads are applied. Existing experiments demonstrated that the development of quasi-instantaneous transient thermal creep, generally referred to as TTC, was dependent on the virgin heating of a mechanically pre-loaded concrete specimen. However, the mechanism behind it is still not fully understood. In this paper, a numerical method is developed to analyze the stress fluctuation and corresponding plastic strain caused by the combination of pre-load and temperature gradient. The results show that the TTC calculated using existing semi-implicit methods is reasonable only at early stage but could be wrong at high temperatures. The sharp increase of TTC beyond around 500 degrees C observed in many tests could be attributed to the implicit inclusion of the extra plastic strain resulted from temperature gradient. By excluding the extra plastic strain generated at different temperature levels, a more accurate formula for calculating TTC is proposed. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Concrete Thermo mechanical load Temperature gradient Transient thermal creep Load induced thermal strain Explicit model

来源：评论

学校读者我要写书评

暂无评论

Axial compressive behavior of seawater and sea-sand concrete (SSC) filled stainless steel tubular columns with FRP confined ssc core 7

Axial compressive behavior of seawater and sea-sand concrete...

引用

7th Asia-Pacific Conference on FRP in Structures, APFIS 2019

作者： Zeng, L. Yu, W.L. Lu, R.Q. Yuan, H. Li, L.J. MOE Key Laboratory of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China School of Civil and Transportation Engineering Guangdong University of Technology Guangzhou510006 China

ISBN: (纸本)9780648752899

The promotion of sea water and sea-sand concrete (SSC) is beneficial to alleviate the resource shortage of fresh water and river-sand, but it is easier to cause the problem of steel corrosion. Owing to good corrosion resistance of fiber-reinforced polymer (FRP) and stainless steel, a novel type of composite, named SSC filled stainless steel tubular columns with FRP confined SSC core (SCFCs), is proposed. In order to study the constraint effect, axial compression tests on 8 SCFC stub columns were conducted, and the influences of parameters as the shape of steel tubes, the existence of FRP tubes, the thickness and the diameter of FRP tubes were analyzed. The test results have shown that the bearing capacity and ductility of SCFCs can be improved by the inner FRP confined SWSSC. FRP contents can help alleviate the phenomenon of steel buckling and further increase the bearing capacity and restrict the dilation of specimens. With similar FRP contents, increasing the diameter of FRP tubes improved the performance of SCFCs more apparently. With similar inner concrete section areas, circular steel tubes has better confinement than square ones. © APFIS 2019. All right reserved.

关键词： Stainless steel

来源：评论

学校读者我要写书评

暂无评论

Study on Adsorption and Dust Suppression Mechanism of Urease-Producing Bacteria on Coal-Soil Mixed Dust

SSRN

引用

SSRN 2023年

作者： Zhao, Yan-Yun Zhang, Ming Hu, Xiang-Ming Feng, Yue Xue, Di Wang, Qing-Shan Geng, Zhi Liu, Yu Zhang, Jing Jia, Xiang-Hua College of Safety and Environmental Engineering Shandong University of Science and Technology Shandong Qingdao266590 China State Key Laboratory of Mine Lab Disaster Prevention and Control Co-found by Shandong Province The Ministry of Science and Technology Shandong University of Science and Technology Shandong Qingdao266590 China Institute of Yellow River Delta Earth Surface Processes and Ecological Integrity Shandong University of Science and Technology Shandong Qingdao266590 China

Air pollution prevention and control is the primary problem faced by coal mines, in which coal dust and soil dust in the air are the most serious pollution. Microbial dust suppressants as a green and efficient means of dust suppression and fixation have received widespread attention from the academic community. However, different coal-soil ratios inevitably affect the dust suppression efficiency of microbial dust suppressants. In this paper, the adsorption mechanism of Bacillus X4 (B.X4), a urease-producing bacteria, on different coal-soil ratios dust surface was investigated to clarify the impact mechanism on the dust suppression of microbial dust suppressants. Both SEM and adsorption isotherms showed that B.X4 could adsorb on dust surface and the adsorption was single-layer adsorption. The adsorption kinetic model was most consistent with the pseudo-second-order kinetic model, indicating that the adsorption was chemical adsorption. Moreover, the adsorption effect between urease-producing bacteria and dust with different coal-soil ratios was different due to the different surface properties and hydrophilicity of coal dust and soil dust. With the increase of soil dust content, the better the adsorption effect, the better the consolidation effect, the better the dust suppression effect. This indicated that the dust suppression effect of microbial dust suppressants could be improved by promoting adsorption performance, which was beneficial to the promotion and application of microbial dust suppressants. Zeta potential, SEM-EDS, and XRD results all demonstrated that CaCO3 was formed in the dust treated with microbial dust suppressants, which could effectively cement the dust and suppress its generation and flying. © 2023, The Authors. All rights reserved.

关键词： Soils

来源：评论

学校读者我要写书评

暂无评论

Defect detection in pipe structures using stochastic resonance of Duffing oscillator and ultrasonic guided waves

引用

INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING 2020年 187卷 104168-104168页

作者： Wu, Jing Hao, Hong Li, Jun Wang, Yan Wu, Zhiheng Ma, Hongwei Dongguan Univ Technol Sch Mech Engn Dongguan 523808 Peoples R China Curtin Univ Ctr Infrastruct Monitoring & Protect Sch Civil & Mech Engn Kent St Bentley WA 6102 Australia Guangzhou Univ Sch Civil Engn Guangzhou 510006 Peoples R China Qufu Power Supply Co State Grid Shandong Elect Power Co Jining 272000 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510006 Peoples R China

Ultrasonic guided wave based non-destructive testing is an effective method to inspect defects in long-distance pipe structures. This paper proposes a novel defect detection approach for the pipes using stochastic resonance of Duffing oscillator and ultrasonic guided waves. Stochastic resonance can improve the signal-to-noise ratio (SNR) in the output signal, because it can enhance the periodic component while attenuate the noise components. A detection system is first developed based on Duffing oscillator. The echo signal between the incident signal and end echo is used as the input to the Duffing oscillator, and the normalized power spectrum of the output signal is calculated to obtain the SNR of the output signal. The SNR curve is shown versus the change of the damping ratio value. When stochastic resonance occurs, the SNR is at the peak, corresponding to the optimal value of damping ratio. With the optimal damping ratio value, the power spectrum of the output signal from the Duffing oscillator is used to detect the characteristic frequency. If there is a distinct characteristic frequency with the same excitation frequency as the guided wave excitation signal, it can be concluded that there is a defect in the pipe. Both numerical simulations and experimental studies are conducted to investigate the accuracy and effectiveness of the proposed approach in defect detection in pipes. The detection results demonstrate that the prop osed approach can significantly enhance the sensitivity of using weak guided wave signals for minor defect detection in pipe structures.

关键词： Ultrasonic guided waves Duffing oscillator Stochastic resonance Defect detection Minor damage Pipe structures

来源：评论

学校读者我要写书评

暂无评论

Preparation of a Viscous Hydrogel and Research on its Flame-Retardant Properties

SSRN

引用

SSRN 2022年

作者： Shi, Mengli He, Zhenglong Zhang, Qian Liang, Yuntao Tang, Hui Hu, Xiangming Xue, Di Wang, Wei Qi, Guansheng College of Safety and environmental engineering Shandong University of Science and Technology Shandong Qingdao266590 China State Key Laboratory of Mining Lab Disaster Prevention and Control Co-found by Shandong Province The Ministry of Science and Technology Shandong University of Science and Technology Shandong Qingdao266590 China State Key Laboratory of Coal Mine Safety Technology China Coal Technology & Engineering Group Corp Shenyang Research Institute Fushun113122 China

The spontaneous combustion of coal restricts the development of green coal mining. Hydrogels are often used to block air leaks and prevent the spontaneous combustion of coal, but traditional hydrogels suffer from poor adhesion and mobility;therefore, to prevent the spontaneous combustion of coal and improve the utilization rate of hydrogels, this study proposes a new type of fire-extinguishing viscous hydrogel, polyacrylic acid-sodium alginate-tannic acid (PAA-SA-TA). The viscosity, air plugging and blocking characteristics, adhesion mechanism, air plugging efficiency, and thermal stability of the PAA-SA-TA hydrogel were analyzed. The results showed that the viscosity of the PAA-SA-TA hydrogel was about 70% higher, and the blocking efficiency and blocking rate were 42.90% and 39.53% higher than those of a poly acrylic acid (PAA) hydrogel, respectively. In addition, the fire extinguishing tests showed that compared with PAA and polyacrylic acid-tannic acid (PAA-TA) hydrogels, PAA-SA-TA evenly covered the surface of the burning coal body, densely wrapped the coal body, filled the cracks, and extinguished the fire without re-ignition. This study provides a new viscous hydrogel for the prevention and control of the spontaneous combustion of coal in mines. © 2022, The Authors. All rights reserved.

关键词： Hydrogels

来源：评论

学校读者我要写书评

暂无评论

Transient Analysis Based on Finite Element Method for Ball Grid Array Package

引用

IOP Conference Series: Earth and Environmental Science 2021年第4期769卷

作者： Wenhao Luo Wei Su Xianshan Dong Zhenhua Nie Agam Tomar MOE Key lab of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou China MOE Key lab of Disaster Forecast and Control in Engineering Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China MOE Key lab of Disaster Forecast and Control in Engineering School of Mechanics and Construction Engineering Jinan University Guangzhou China Faculty of Engineering and Mathematical Sciences University of Western Australia MOE Key lab of Disaster Forecast and Control in Engineering Perth Australia

In this paper, finite element simulation is carried out for BGA sample. The authors establishes the model of fixture, ceramic panel and metal sheet. Based on this model, several layers papers are laid on the metal sheet for simulation test. Then, ANASYS Workbench is used to conduct transient analysis of the samples to study the influence of different thickness papers on acceleration and time. The results provide useful reference for the adjustment of dynamic response parameters.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Selective laser melting of Ti-TiN composites: Formation mechanism and corrosion behaviour in H2SO4/HCl mixed solution

引用

JOURNAL OF ALLOYS AND COMPOUNDS 2021年 863卷 158721-158721页

作者： Zhao, Yu Wu, Changyi Zhou, Shengfeng Yang, Junjie Li, Wei Zhang, Lai-Chang Jinan Univ Inst Adv Wear & Corros Resistance & Funct Mat Guangzhou 510632 Peoples R China Hunan First Normal Univ Dept Educ Sci Changsha 410205 Hunan Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Edith Cowan Univ Sch Engn 270 Joondalup Dr Perth WA 6027 Australia

Electrochemical measurements and microstructural analysis were performed to study the formation mechanism and corrosion behavior in mixed solution of the Ti-TiN composites produced by selective laser melting (SLM) and commercially pure titanium (CP-Ti) for comparison. The Ti-TiN composites comprise alpha'-Ti and delta-TiN, where the acicular alpha' martensite is refined compared to that in the CP-Ti. The passive film of all samples comprises TiO2, Ti2O3 and TiO. Compared to CP-Ti, the Ti-TiN composites demonstrate higher corrosion resistance, owing to the fine grains, the initial rapid passivation and the corrosion shadow protection effect of the alloyed reaction layer on the alpha'-Ti. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Ti-TiN composites Selective laser melting Corrosion resistance Passive films Microstructure

来源：评论

学校读者我要写书评

暂无评论

Structural damage identification based on unsupervised feature-extraction via Variational Auto-encoder

引用

MEASUREMENT 2020年 160卷 107811-107811页

作者： Ma, Xirui Lin, Yizhou Nie, Zhenhua Ma, Hongwei Jinan Univ Coll Mech & Construct Engn Guangzhou Guangdong Peoples R China Minist Educ China Key Lab Disaster Forecast & Control Engn Guangzhou Guangdong Peoples R China Dongguan Univ Technol Dongguan Peoples R China

Structural health monitoring (SHM) is a practical tool for assessing the safety and system performance of existing structures. And structural damage identification has become the core of a SHM system. However, how to extract damage-sensitive features from structural response has become a challenging problem. Thus deep learning methods have attracted increasing attention for its ability to effectively extract high-level abstract features form raw data. This paper presents a damage detection method based on Variational Auto-encoder (VAE), one of the most important generative models in unsupervised deep learning. In this paper, VAE is used to process responses of the structure, which reduces the high-dimensional data to low-dimensional feature space, and then restores the original data from the low-dimensional representations. This structure forces the VAE to learn the essential features hidden behind the complex data. Taking advantage of this characteristic, we apply the VAE to damage identification task of a bridge under moving vehicle. The results of both numerical simulation and experiment are proved that the proposed method can accurately identify the structural damage/s. This method directly analyzes the measured responses of the structure without the structural element model and baseline data. It is a baseline-free data driven method, which is suitable for real engineering application in SHM. (C) 2020 Published by Elsevier Ltd.

关键词： Structural health monitoring Deep learning Variational auto-encoder Moving load

来源：评论

学校读者我要写书评

暂无评论

Sparse regularization for traffic load monitoring using bridge response measurements

引用

MEASUREMENT 2019年 131卷 173-182页

作者： Zhong, Jiwei Liu, Huanlin Yu, Ling Wuhan Univ Technol Wuhan 430070 Hubei Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Guangdong Peoples R China State Key Lab Hlth & Safety Bridge Struct Wuhan 430034 Hubei Peoples R China Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Guangdong Peoples R China

Traffic load monitoring (TLM) is one of important issues in bridge structural health monitoring (SHM), but there still exist such problems as lack of accuracy and efficiency for the existing methods. In this study, a sparse regularization approach is proposed for TLM based on analytical model and redundant dictionary. Firstly, an unknown moving traffic load is deemed as a combination of static and time-varying components so that a redundant dictionary can be established to independently express them. The static component is expressed by a basis vector whose elements are identical, and the time-varying one by wavelet functions for their good multi-resolution analysis characteristics. Then, the TLM problem is converted to determine a coefficient vector of dictionary, and the l(1)-norm regularization technique is adopted to obtain a sparse solution to the coefficient vector. Finally, a series of experimental studies on a hollow steel beam bridge under crossing a moving model car are conducted in laboratory to assess the effectiveness of the proposed method. Furthermore, comparative studies are carried out for assessing the effect of different measurement parameters, such as moving car speeds, car weights, strain and acceleration response data, redundant dictionaries as well as selection of regularization parameters, on the proposed method. The illustrated TLM results show that the dictionary used for TLM in this study can independently distinguish the static and time-varying components of moving traffic loads. The proposed method can effectively identify the total weight of moving traffic loads with a higher accuracy, which provides a great potential for monitoring moving vehicle loads on bridges.

关键词： Traffic load monitoring (TLM) Moving force identification (MFI) Redundant dictionary l(1)-Norm regularization Analytical model Wavelet functions

来源：评论

学校读者我要写书评

暂无评论

Concrete reinforced with macro fibres recycled from waste GFRP

引用

CONSTRUCTION AND BUILDING MATERIALS 2021年 310卷 125063-125063页

作者： Fu, Bing Liu, K. C. Chen, J. F. Teng, J. G. Jinan Univ Sch Mech & Construct Engn Guangzhou 510632 Peoples R China Jinan Univ MOE Key Lab Disaster Forecast & Control Engn Guangzhou 510632 Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Peoples R China Southern Univ Sci & Technol Dept Ocean Sci & Engn Shenzhen 518000 Peoples R China Southern Marine Sci & Engn Guangdong Lab Guangzhu Guangzhou 511458 Peoples R China

Fibre reinforced polymer (FRP) composites are widely used in many industries due to their excellent mechanical and durability properties. This means that an increasing amount of FRP waste, arising from production, processing and decommissioning, needs to be processed. Common FRP composites are normally thermoset and nonbiodegradable, posing a significant environmental threat if they are not disposed of properly at their end of life. While recycling of FRP is environmentally desirable, almost all existing recycling methods, which are based on either thermal, chemical or mechanical processes, are economically unviable if governmental subsides are not available. The recycling of glass FRP (GFRP) waste, which accounts for over 95% of all types of FRP waste by weight, is even more economically challenging than the recycling of carbon FRP (CFRP) waste due to the lesser economic value of the former. This paper explores a novel mechanical method for recycling GFRP waste by processing it into macro fibres for reinforcing concrete, with the resulting material referred to as macro fibre reinforced concrete (MFRC). The mechanical properties of MFRC were investigated. The test results showed that the addition of macro fibres had two major effects on the concrete: (1) the workability of concrete depends strongly on the macro fibre volume ratio, with the slump value reducing from 176 mm to 83 mm as the macro fibre volume ratio increased from 0% to 1.5%;(2) the flexural strength and toughness of the concrete be greatly enhanced by the addition of macro fibres, e.g., by 1.3 and 230 times when the macro fire value ratio was 1.5%. The proposed recycling method for waste GFRP is therefore believed to be both technically feasible and economically attractive.

关键词： GFRP Waste Mechanical recycling Macro fibre Concrete

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：