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1
Content available Microstructure and Mechanical Properties of Stainless Steel/Aluminum Multilayer Composites by One-Step Explosive Welding
Hu Xiaoyan, Liu Yingbing, Yang Li, Huang Xiaochen
Archives of Metallurgy and Materials
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2023
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Vol. 68, iss. 3
1211--1217
EN
The stainless steel/aluminum multilayer composites were prepared by one-step explosive welding using ammonium nitrate explosive with two different thicknesses. The microstructure and mechanical properties of the multilayer composites were examined. There is a thin metallurgical melting zone at each bonding interface, consisting mostly of iron and aluminum elements. However, the micro-crack appears in the second metallurgical bonding zone obtained using the explosive of 24 mm thickness. The micro-hardness values at the four bonding interfaces are higher than those of bulk 1060 aluminum and 304 ­stainless steel. The yield strength of the multilayer composites obtained in the two cases is higher than that of the original 304 stainless steel while the tensile strength is between those of the original 1060 aluminum and 304 stainless steel. Meanwhile, the tensile strength and yield strength of multilayer composites obtained by explosive welding with explosive of 20 mm thickness are relatively higher.
2
Content available Microstructure and Mechanical Properties of Stainless Steel/Aluminum Multilayer Composites by One-Step Explosive Welding
Hu Xiaoyan, Liu Yingbin, Yang Li, Huang Xiaochen
Archives of Metallurgy and Materials
|
2023
|
Vol. 68, iss. 3
939--946
EN
The stainless steel/aluminum multilayer composites were prepared by one-step explosive welding using ammonium nitrate explosive with two different thicknesses. The microstructure and mechanical properties of the multilayer composites were examined. There is a thin metallurgical melting zone at each bonding interface, consisting mostly of iron and aluminum elements. However, the micro-crack appears in the second metallurgical bonding zone obtained using the explosive of 24 mm thickness. The microhardness values at the four bonding interfaces are higher than those of bulk 1060 aluminum and 304 stainless steel. The yield strength of the multilayer composites obtained in the two cases is higher than that of the original 304 stainless steel while the tensile strength is between those of the original 1060 aluminum and 304 stainless steel. Meanwhile, the tensile strength and yield strength of multilayer composites obtained by explosive welding with explosive of 20 mm thickness are relatively higher.
3
Content available Threshold effect of economic growth on domestic waste production : evidence from China
Yang Li, Wang Hong-Yan, Yi Lan, Shi Xiang-Zhen, Deng Wei
Archives of Environmental Protection
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2022
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Vol. 48, no. 4
13--24
EN
Since the implementation of the compulsory sorting of domestic waste policy in China, the participation rate of residents is low, which leads to the unsatisfactory result of terminal reduction of domestic waste. Therefore, the problem of domestic waste reduction still needs to rely on source reduction. Based on the panel data of 29 provincial capitals in China from 2009 to 2018, this study conducts a comprehensive threshold effect test on per capita GDP and other influencing factors of domestic waste production, conducts panel threshold regression for the factors with threshold value, and explores the nonlinear relationship between per capita GDP and domestic waste production under the influence of different threshold variables. The results show that when the urban population density is less than 272 people/km2, the increase of 1% of per capita GDP will lead to a decrease of 0.251% in the domestic waste production, otherwise, it will lead to an increase of 0.249%; when the per capita consumption expenditure is less than the threshold value of 10,260 yuan/year, the influence coefficient of per capita GDP is 0.155, which increases to 0.207 above the threshold. When the share of tertiary industry is taken as the threshold variable, the two threshold values are 61% and 71% respectively. Through the analysis of control variables, it has been found that population size and amount of courier per capita have significant positive effects on domestic waste production, while gas permeability and the number of non-governmental organizations have significant negative effects.
4
Content available Liquid bridge in slit pore geometry
Hu Junhui, Wu Mengjiao, Bai Kezhao, Yang Li
Journal of Theoretical and Applied Mechanics
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2021
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Vol. 59 nr 1
135--142
EN
In this work, the morphology of a liquid bridge in a slit pore geometry was investigated as a function of both the bridge height and aspect ratio (height/width). The end contour interface of the liquid bridge was modeled by using a saddle shape, and the liquid-air interface was described via an arc of a circle. By employing the free energy approach, a simple formula was obtained to predict variation of the pinning angle as a function of the distance between the slits. The pinning angle depended on the liquid volume and on both the wetting properties and the geometry of the system (height and width). The critical aspect ratio at which the liquid bridge meniscus transitioned from concave to convex was determined. The calculations were in good agreement with the experimental data. The morphology of the liquid bridges in a slit pore geometry can be used in various fields such as the packaging of electronic and micro-electromechanical systems.
5
Content available Comparative Study of the Penetration Characteristics of Ni-Al and Pure Cu Shaped Charge Liners
Liu Yingbin, Zhang Chaoxia, Hu Xiaoyan, Yang Li, Sun Miao, Zhang Zeng, Yuan Lei
Central European Journal of Energetic Materials
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2021
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Vol. 18, no. 2
199--222
EN
In order to investigate the correlation between the reactivity of Ni-Al and micro-structural differences in the crater walls, penetration experiments were performed with Ni-Al and pure Cu shaped charge liners (SCLs). The experimental results showed that the average penetration depth of Cu jets is 2.3 times that of Ni-Al jets, but the crater entrance diameter of Ni-Al jets is larger by 26.6%. The microstructure of the recovered targets was characterized using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and a Vickers micro-hardness system. The Ni-Al “white” band was thicker than that of Cu because it releases a lot of heat. The micro-hardness test showed that the “white” band had a relatively high hardness, and the “white” band hardness in the tail was more significant than that in the head. However, the micro-structural evolution of the crater walls is related to the reactivity of Ni-Al, but is also related to other factors. Combined with the macro penetration results and the evolution of the micro-structure of the crater walls, the “white” band can absorb impact energy more strongly and weaken the jet breaking ability or armour protection ability.These results can provide more valuable reference for designing shaped charge warheads and protection structures.
6
Content available Short-term load prediction model combining FEW and IHS algorithm
Yu Mingxing, Zhu Jiazheng, Yang Li
Archives of Electrical Engineering
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2019
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Vol. 68, nr 4
907--923
EN
:Accurate prediction of power load plays a crucial role in the power industry and provides economic operation decisions for the power operation department. Due to the unpredictability and periodicity of power load, an improved method to deal with complex nonlinear relation was adopted, and a short-term load forecasting model combining FEW (fuzzy exponential weighting) and IHS (improved harmonic search) algorithms was proposed. Firstly, the domain space was defined, the harmony memory base was initialized, and the fuzzy logic relation was identified. Then the optimal interval length was calculated using the training sample data, and local and global optimum were updated by optimization criteria and judging criteria. Finally, the optimized parameters obtained by an IHS algorithm were applied to the FEW model and the load data of the Huludao region (2013) in Northeast China in May. The accuracy of the proposed model was verified using an evaluation criterion as the fitness function. The results of error analysis show that the model can effectively predict short-term power load data and has high stability and accuracy, which provides a reference for application of short-term prediction in other industrial fields.
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