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Edge crack damage analysis of AZ31 magnesium alloy hot-rolled plate improved by vertical roll pre-rolling

Journal of Magnesium and Alloys 2023年第6期11卷 2151-2164页

作者： Zhiquan Huang Chuanlu Qi Jinchao Zou Hongyu Lai Hao Guo Junpeng Wang School of Mechanical Engineering Taiyuan University of Science and TechnologyTaiyuan 030024China Nsk(China)Research&Development Co. Ltd.Kunshan 215332China

In the present study,through vertical roll pre-rolling of AZ31 magnesium alloy hot-rolled plate at room temperature,the effect of different vertical roll pre-rolling reduction on edge crack of the plate during flat rolling was systematically *** evolution of microstructure and texture in the edge and middle of the plate after vertical roll pre-rolling,heating and rolling was analyzed by using EBSD *** results show that during the vertical roll pre-rolling,{10–12}primary twins and{10–12}-{10–12}secondary twins dominated the edge deformation,while{10–12}primary twins dominated the middle *** the increase of vertical roll pre-rolling reduction,the twin volume fraction of the edge and the middle increased,and the difference between them decreased *** heating,the twin orientation caused by vertical roll pre-rolling was still maintained,and there was a significant difference in grain size between the edge and the *** the reduction rate of flat rolling was 30%,cracks have already appeared in the initial plate,while the vertical roll pre-rolled samples showed extremely high rolling *** the reduction rate of flat rolling was 50%,the 8PR sample still had no crack *** addition,after flat rolling of 50%,the initial plate showed a strong basal texture,while the maximum pole density of the 8PR plate was small,and the texture distribution was very scattered,showing the characteristics of weak orientation.

关键词： AZ31 magnesium alloy Vertical roll pre-rolling Edge crack {10–12}Twins Texture

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A hybrid electromechanical coupling system optimisation

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International Journal of Powertrains 2023年第3期12卷 240-261页

作者： Liu, Xuewu Zhao, Jiangling Liu, Zhuochao Xu, Xiangyang Qi, Hongzhong Zhu, Yongming Dong, Peng Wang, Shuhan Department of Automotive Engineering School of Transportation Science and Engineering Beihang University Beijing100191 China GAC Automotive Research and Development Center Guangzhou511434 China

Hybrid electric vehicles cannot only save energy and reduce emissions, but also solve the range anxiety problem of electric vehicles, therefore becoming an important breakthrough direction of low-carbon vehicles. The electromechanical coupling system is an important part of hybrid electric vehicles, including the single-motor hybrid system, the series-parallel hybrid system, the power-split hybrid system, and other different routes. First, three basic configurations are established for the three technical routes respectively. Then, the optimal configuration of each basic configuration is obtained through optimisation analysis. Finally, the series-parallel technical routes are confirmed by comprehensive comparison, and the configuration design is carried out. This paper systematically describes the whole process of scheme design, which can provide reference for other automobile companies that develop electromechanical coupling systems for hybrid electric vehicles. Copyright © 2023 Inderscience Enterprises Ltd.

关键词： Hybrid vehicles

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Influences of regeneration atmospheres on structural transformation and renderability of fluidized catalytic cracking catalyst

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Chinese Journal of Chemical engineering 2023年第11期63卷 71-80页

作者： Haigang Zhang Zhongjie Shen Jianhong Gong Haifeng Liu National Energy Coal Gasification Technology Research and Development Center and Shanghai Engineering Research Center of Coal Gasification East China University of Science and TechnologyShanghai 200237China Sinopec Research Institute of Petroleum Processing Beijing 100083China

The regeneration of fluidized catalytic cracking(FCC)catalysts is an essential process in petroleum *** current study focused the regeneration reaction characteristics of spent fluidized catalytic cracking catalyst(SFCC)at different atmospheres with influences on pore evolution and activity,for a potential way to reduce emission,produce moderate chemical product(CO),and maintain catalyst *** results show that regeneration in air indicates a satisfaction on removing coke on the catalyst surface while giving a poor effect on eliminating the coke inside *** is attributed that the combustion in air led to a higher temperature and further transformed kaolinite phase to silicaaluminum spinel crystals,which tended to collapse and block small pores or expand large pores,with similar results observed in pure O_(2)***,catalysts regenerated in O_(2)/CO_(2)diminished the combustion damage to the pore structure,of which the micro porosity after regeneration increased by 32.4% and the total acid volume rose to 27.1%.The regeneration in pure CO_(2)displayed low conversion rate due to the endothermic reaction and low *** coexistence of gasification and partial oxidation can promote regeneration and maintain the original structure and good ***,a mechanism of the regeneration reaction at different atmospheres was revealed.

关键词： Fluidized catalytic cracking Coke deposit Regeneration Pore structure Gasification and combustion

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Synergistic extraction of rare earth elements and alumina from coal fly ash by potassium pyrosulfate

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Journal of Rare Earths 2024年第4期42卷 749-758页

作者： Jingjing Zou Yiping Sun Chunbin Guo Daye Chen Yonghong Song Yongfeng Wu Zhaotianhui Li Department of Environment Science and Engineering Liaoning Technical UniversityFuxin23000China Department of Materials Science and Engineering Liaoning Technical UniversityFuxin123000 China Technology Research and Development Department Chinese Institute of Coal ScienceBeijing100013China Shenhua Zhungeer Energy and Resource Comprehensive Development Co. Ltd.Erdos10300China Liaoning Yingguan High-tech Ceramic Co. Ltd.Jinzhou121213China

Although coal fly ash(CFA)contains a high content of rare earth elements(REEs),the related extraction methods have limitations because of their low efficiencies,high levels of energy consumption,and other *** address these problems,in this study,we examined the coextraction of REEs and Al_(2)O_(3)from two types of Al_(2)O_(3)-rich CFA,pulverized CFA(PCFA)and circulating fluidized bed fly ash(CFBFA)using low-temperature calcination in the presence of K_(2)S_(2)O_(7).The total REEs,heavy REEs(HREEs),and light REEs(LREEs)extraction efficiencies were determined using different K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios and calcination temperatures and correlated with the Al_(2)O_(3) extraction efficiency using Pearson correlation coefficient *** REEs are concentrated within CFA particles encapsulated in an aluminosilicate glass phase,and the REEs extraction efficiency is related to the form of Al in *** extraction efficiencies of Al_(2)O_(3) and REEs increase as the K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratio and calcination temperature increase,and the extraction selectivity of the more industrially valuable HREEs from CFBFA is *** high K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios,the extraction of REEs from PCFA is more efficient than that from CFBFA with the regeneration of the highly active Al-O-Si bonds in *** Al_(2)O_(3) extraction efficiencies of PCFA as well as CFBFA correlate strongly with the total REEs,HREEs,and LREEs extraction *** developed extraction technology has the potential to promote CFA valorization and expand REEs resources,thus mitigating the bottlenecks of REEs procurement.

关键词： Rare earths Alumina Coal fly ash Potassium pyrosulfate Calcination Extraction

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Dynamic response of armor-piercing bullets to blunt and penetration with protective gelatin

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Theoretical & Applied Mechanics Letters 2024年第4期14卷 270-279页

作者： Rui Yuan Yaoke Wen Weixiao Nie Dongxu Liu Zhouyu Shen Haoran Xu School of Mechanical Engineering Nanjing University of Science&TechnologyNanjing 210094China Research and Development Center Liaoshen Industrial Group Co.Ltd.Shenyang 110045China

To investigate the coupled damage mechanism of blunt impact and bullets penetration after penetrating ballistic plates against human body targets,experiments were conducted using 6.8 mm caliber armor-piercing bullets against gelatin targets with protective coatings.A numerical analysis model was developed to simulate bullet penetration into gelatin with protective coatings,obtaining endpoint characteristic quantities such as bullet velocity changes,changes in energy distribution,pressure,stress,and stress wave variations within the gelatin target after *** results indicate that at a velocity of 640 m·s^(-1),the 6.8 mm caliber armor-piercing round failed to penetrate the ballistic plate yet still caused a blunt impact depression of 37 mm in *** conditions where the bullet did not penetrate the ballistic plate,approximately 80%of the bullet's kinetic energy was absorbed by the ballistic *** a velocity of 740 m·s^(-1),the bullet penetrated the ballistic plate,resulting in a blunt impact depression depth of 56 mm and an instantaneous cavity with a maximum diameter of 60 *** the process of penetrating the ballistic plate,approximately 50%of the bullet's kinetic energy was absorbed by the ballistic plate,and about 40%of the remaining kinetic energy transferred into the gelatin during the penetration of the target.

关键词： Armor-piercing bullet Ballistic plate Ballistic gelatin Temporary cavity

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Redundancy and hierarchical cluster analyses for characterizing geomorphic features contributing to the formation of landslide dams

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Landslides 2024年第11期21卷 2845-2857页

作者： Chen, Ho-Wen Chen, Chien-Yuan Chuang, Yen-Hsun Department of Environmental Science and Engineering Tunghai University Taichung407224 Taiwan Department of Civil and Water Resources Engineering National Chiayi University Chiayi60004 Taiwan Department of Environmental Science and Engineering/Office of Sustainable Development and Institutional Research Tunghai University Taichung407224 Taiwan

Landslides frequently produce dams that can cause widespread destruction when breached. Several factors influence the formation of landslide dams. This study used redundant analysis and hierarchical cluster analysis to investigate geomorphic features contributing to the formation of landslide dams. Eight landslide geomorphic features corresponding to the width of the river beneath the landslide and four geomorphic indices were selected to explore the geomorphic characteristics of 28 river-damming and 59 nondamming landslides in Taiwan. The redundancy analysis revealed that the geomorphic features derived for the river-damming landslides differed from those derived for the nondamming landslides. The width of the river beneath the landslide was noted to be strongly correlated with the aspect of nondamming landslides. Hierarchical cluster analysis was used to cluster the river-damming landslides into three clusters based on the geomorphic features influencing dam formation. Based on these clusters, the landslide site may be damming rivers under different geomorphic combination conditions. © Springer-Verlag GmbH Germany, part of Springer Nature 2024.

关键词： Landslides

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Novel Framework for an Intrusion Detection System Using Multiple Feature Selection Methods Based on Deep Learning

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Tsinghua science and Technology 2024年第4期29卷 948-958页

作者： A.E.M.Eljialy Mohammed Yousuf Uddin Sultan Ahmad Department of Information Systems College of Computer Engineering and SciencesPrince Sattam Bin Abdulaziz UniversityAlkharjSaudi Arabia Department of Computer Science College of Computer Engineering and SciencesPrince Sattam Bin Abdulaziz UniversityAlkharjSaudi Arabiaand also with University Center for Research and Development(UCRD)Department of Computer Science and EngineeringChandigarh UniversityPunjabIndia

Intrusion detection systems (IDSs) are deployed to detect anomalies in real time. They classify a network’s incoming traffic as benign or anomalous (attack). An efficient and robust IDS in software-defined networks is an inevitable component of network security. The main challenges of such an IDS are achieving zero or extremely low false positive rates and high detection rates. Internet of Things (IoT) networks run by using devices with minimal resources. This situation makes deploying traditional IDSs in IoT networks unfeasible. Machine learning (ML) techniques are extensively applied to build robust IDSs. Many researchers have utilized different ML methods and techniques to address the above challenges. The development of an efficient IDS starts with a good feature selection process to avoid overfitting the ML model. This work proposes a multiple feature selection process followed by classification. In this study, the Software-defined networking (SDN) dataset is used to train and test the proposed model. This model applies multiple feature selection techniques to select high-scoring features from a set of features. Highly relevant features for anomaly detection are selected on the basis of their scores to generate the candidate dataset. Multiple classification algorithms are applied to the candidate dataset to build models. The proposed model exhibits considerable improvement in the detection of attacks with high accuracy and low false positive rates, even with a few features selected.

关键词： random forest feature selection decision tree software-defined network logistic regression intrusion detection system XGB classifier AdaBoost

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High-static-low-dynamic stiffness isolator based on an electromagnetic negative stiffness spring with long linear stroke

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science China(Technological sciences) 2024年第3期67卷 740-752页

作者： YUAN ShuJin WU YaJun SONG DaiPing PU HuaYan MOU LiSheng HOU Lei ZHAO JingLei LI XuePing LUO Jun WU Jie HUANG XiaoXu State Key Laboratory of Mechanical Transmissions Chongqing UniversityChongqing 400044China China Aerodynamics Research and Development Center Mianyang 621000China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

Negative stiffness mechanisms can improve low-frequency vibration isolation performance and have been widely used in the vibration isolation of precision equipment. However, the negative stiffness mechanism usually introduces a nonlinear stiffness,resulting in a nonlinear response and worsening the vibration isolation performance, especially under large amplitude *** this paper, an electromagnetic spring with linear negative stiffness(ESLNS) is proposed, in which the antagonistic ampere forces of the energized coils are used to generate negative stiffness within a long linear stroke. The magnetic field distribution is improved through the design of the magnetic circuit, thereby increasing the stiffness generation efficiency. The stiffness can be adjusted bidirectionally by current within the range of positive and negative stiffness. An electromagnetic stiffness model was established based on the equivalent magnetic circuit method. Experimental measurements verified the accuracy of the model and proved the linearity of the electromagnetic spring. A vibration isolator with high static and low dynamic stiffness(HSLDS) based on the ESLNS is designed and tested. The experimental results prove that the introduction of the ESLNS can effectively expand the isolation frequency band without changing the equilibrium position. Moreover, the vibration isolator with ESLNS does not produce nonlinear response. The proposed electromagnetic spring with linear negative stiffness extends the application range of HSLDS isolators to a large amplitude vibration environment.

关键词： linear negative stiffness mechanism low-frequency vibration isolation electromagnetic spring vibration control

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Chemical and mechanical properties of stainless, environment-friendly, and nonflammable Mg alloys (SEN alloys): A review

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Journal of Magnesium and Alloys 2024年第3期12卷 841-872页

作者： Jong Un Lee Hyun Ji Kim Sang-Cheol Jin Ye Jin Kim Young Min Kim Bong Sun You Jun Ho Bae Sung Hyuk Park Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Metallurgical Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Missile Research Institute Agency for Defense DevelopmentDaejeon 34060Republic of Korea

This review article provides overall understanding of stainless,environment-friendly,and nonflammable Mg alloys(SEN alloys)recently developed at the Korea Institute of Materials *** alloys are produced by adding small amounts of Ca and Y(each<1 wt%)into commercial Mg–Al based alloys,resulting in exceptional ignition and corrosion resistances and impressive mechanical *** main advantages of SEN alloys are as follows.(1)A dense multi-oxide layer of SEN alloys comprising MgO,CaO,and Y_(2)O_(3) impedes the outward dispersion of Mg vapor and the inward penetration of O_(2) during oxidation,thereby enhancing the oxidation and ignition resistances.(2)The presence of Ca-and Y-based second-phase particles in SEN alloys can enhance their corrosion resistance because Ca-containing particles prevent the spread of corrosion,and the replacement of Al-containing particles with less noble ones containing Y(e.g.,Al–Mn–Y or Al–Y particles)retards corrosion.(3)The addition of minor amounts of Ca and Y renders excellent mechanical properties due to improved strengthening *** enhanced properties are attributed to more pronounced dynamic recrystallization and grain refining behaviors caused by the second-phase particles during extrusion.(4)Despite the presence of various types of second-phase particles,the fatigue properties of SEN9 alloys are similar to those of commercial AZ91 alloys.(5)Simultaneous introduction of Ca and Y suppresses the formation of Mg17Al12 discontinuous precipitates during aging,leading to the enhanced elongation of aged SEN alloys.(6)Adding mischmetal into the SEN9 alloy leads to a six-fold enhancement in ***,the studies conducted on SEN alloys demonstrate their excellent ignition and corrosion resistances and mechanical properties,which broaden the industrial applications of Mg alloys by addressing their inherent weaknesses.

关键词： SEN magnesium alloy Corrosion resistance Ignition resistance Mechanical properties Extrudability.

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HRRP Target Recognition Based on Modified Gradient Boosting Decision Tree 2

HRRP Target Recognition Based on Modified Gradient Boosting ...

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2nd IEEE International Conference on Signal, Information and Data Processing, ICSIDP 2024

作者： Yu, Zhenlin Liu, Shengqi Wang, Wei Wang, Dong Wu, Zhongjie Hu, Yuhao Xi'an Electronic Engineering Research Institute Research and Development Department Changsha China National University of Defense Technology College of Electronic Science and Technology Changsha China Xi'an Electronic Engineering Research Institute Research and Development Department Xi'an China

ISBN: (纸本)9798331515669

Focused on radar automatic target recognition in open set environment, Extreme Value Theory (EVT) is introduced to modify Gradient Boosted Decision Trees (GBDT). We mark the method as Open Set Gradient Boosted Decision Trees (OSGBDT) in the paper. OSGBDT is structured with two steps. First, EVT is utilized to model the distances distribution among samples across features. Positive samples with closely spaced intervals are grouped into the same leaf node during decision tree splitting. Next, EVT is used to model the outputs of prediction models for each class. The probability that a test sample belongs to an unknown class is estimated. Experimental results based on High Resolution Range Profiles (HRRP) database demonstrate that OSGBDT outperforms state-of-the-art open set recognition methods. © 2024 IEEE.

关键词： Radar target recognition

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