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China Foundry 2024年第1期21卷 11-19页

作者： Wen-ning Liu Wei Zhang Peng-yue Wang Yi-xian Liu Xiang-yi Jiao Ao-xiang Wan Cheng-gang Wang Guo-dong Tong Shou-mei Xiong School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing technology Tsinghua UniversityBeijing 100084Beijing China FAW Group co. Ltd.Changchun 130013China China FAW Foundry co. Ltd.Changchun 130013China

The effect of slow shot speed on externally solidified crystal(ESC),porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microsco.y(OM),scanning electron microsco.y(SEM)and laboratory co.puted tomography(CT).Results showed that the newly developed AlSi9MnMoV alloy exhibited improved mechanical properties when co.pared to the AlSi10MnMg *** AlSi9MnMoV alloy,which was designed with trace multico.ponent additions,displays a notable grain refining effect in co.parison to the AlSi10MnMg *** elements Ti,Zr,V,Nb,B promote heterogeneous nucleation and reduce the grain size of primaryα-*** a lower slow shot speed,the large ESCs are easier to form and gather,developing into the dendrite net and *** an increase in slow shot speed,the size and number of ESCs and porosities significantly *** addition,the distribution of ESCs is more dispersed and the net-shrinkage *** tensile property is greatly improved by adopting a higher slow shot *** ultimate tensile strength is enhanced from 260.31 MPa to 290.31 MPa(increased by 11.52%),and the elongation is enhanced from 3.72%to 6.34%(increased by 70.52%).

关键词： hypoeutectic Al-Si alloy high pressure die casting porosity externally solidified crystal tensile property

Neural Network Robust co.trol Based on co.puted Torque for Lower Limb Exoskeleton

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 83-99页

作者： Yibo Han Hongtao Ma Yapeng Wang Di Shi Yanggang Feng Xianzhong Li Yanjun Shi Xilun Ding Wuxiang Zhang School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Beihang Goer(WeiFang)Intelligent Robot co. Ltd.Beihang UniversityWeifangChina Research Center of Satellite technology Harbin Institute of TechnologyHarbinChina beijing Xinfeng Aerospace Equipment co. LtdBeijingChina

The lower limb exoskeletons are used to assist wearers in various scenarios such as medical and industrial *** modeling errors of the exoskeleton in different application scenarios pose challenges to the robustness and stability of its co.trol *** Radial Basis Function(RBF)neural network is used widely to co.pensate for modeling *** order to solve the problem that the current RBF neural network co.trollers cannot guarantee the asymptotic stability,a neural network robust co.trol algorithm based on co.puted torque method is proposed in this paper,focusing on trajectory *** innovatively inco.porates the robust adaptive term while introducing the RBF neural network term,improving the co.pensation ability for modeling *** stability of the algorithm is proved by Lyapunov method,and the effectiveness of the robust adaptive term is verified by the *** wearing the exoskeleton under different walking speeds and scenarios were carried out,and the results show that the absolute value of tracking errors of the hip and knee joints of the exoskeleton are co.sistently less than 1.5°and 2.5°,*** proposed co.trol algorithm effectively co.pensates for modeling errors and exhibits high robustness.

关键词： Lower limb exoskeleton Model co.pensation RBF neural network co.puted torque method

A molecular insight into co.e formation process of vacuum residue in thermal cracking reaction

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Petroleum Science 2024年第3期21卷 2130-2138页

作者： Ji-Guang Li Xin Guo Huan-Di Hou Heavy Oil Processing Department Sinopec Research Institute of Petroleum Processing Co.LtdBeijing100083China

Understanding the co.ing behaviors has been co.sidered to be really essential for developing better vacuum residue processing technologies.A battery of thermal cracking tests of typical vacuum residue at 410℃ with various reaction time were performed to evaluate the co.e formation *** total yields of ideal co.ponents including naphtha,atmospheric gas oil(AGO)and vacuum gas oil(VGO)of thermal cracking reactions increased from 10.89%to 40.81%,and the co.version ratios increased from8.05%to 43.33%with increasing the reaction time from 10 to 70 *** asphaltene co.tent increased from 12.14%to a maximum of 22.39%and then decreased,and this maximum of asphaltene co.tent occurred at the end of the co.ing induction *** asphaltenes during the co.ing induction period,at the end and after co.ing induction period of those tested thermal cracking reactions were characterized to disclose the structure changing rules for co.e formation process,and the co.e formation pathways were discussed to reveal the co.e formation process at molecular level.

关键词： Vacuum residue Thermal cracking Asphaltene co.ing induction period Sulfur Nitrogen

Effect of mesopore spatial distribution of HZSM-5 catalyst on zinc state and product distribution in 1-hexene aromatization

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Chinese Journal of Chemical Engineering 2024年第3期67卷 16-26页

作者： Chenhao Wei Di Gao Guohao Zhang Liang Zhao Jinsen Gao Chunming Xu The State Key Lab of Heavy Oil Processing China University of Petroleum(Beijing)Beijing 102249China SINOPEC Research Institute of Petroleum Processing co. Ltd.Beijing 100083China

1-hexene aromatization is a promising technology to co.vert excess olefin in fluid catalytic cracking(FCC)gasoline to high-value benzene(B),toluene(T),and ***,the increasing market demand of xylene has put forward higher requirements for new generation of *** increasing xylene yield in 1-hexene aromatization,the effect of mesopore structure and spatial distribution on product distribution and Zn loading was *** with different mesopore spatial distribution were prepared by post-treatment of parent HZSM-5 zeolite,including NaOH treatment,tetra-propylammonium hydroxide(TPAOH)treatment,and *** was found the evenly distributed mesopore mainly prolongs the catalyst lifetime by enhancing diffusion properties but reduces the aromatics selectivity,as a result of damage of micropores close to the catalyst *** the selectivity of high-value xylene can be highly promoted when the mesopore is mainly distributed interior the ***,the state of loaded Zn was also affected by mesopores spatial *** the optimized catalyst,the xylene selectivity was enhanced by 12.4%co.pared with co.ventional Zn-loaded parent HZSM-5 catalyst at co.version over 99%.It was attributed to the synergy effect of mesopores spatial distribution and optimized acid *** work reveals the role of mesopores in different spatial positions of 1-hexene aromatization catalysts in the reaction process and the influence on metal distribution,as well as their synergistic effect two on the improvement of xylene selectivity,which can improve our understanding of catalyst pore structure and be helpful for the rational design of high-efficient catalyst.

关键词： 1-Hexene aromatization Alkali treatment Xylene selectivity Mesopores Zinc state

Transient Damping of Virtual Synchronous Generator for Enhancing Synchronization Stability during Voltage Dips

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CES Transactions on Electrical Machines and Systems 2024年第2期8卷 143-151页

作者： Shitao Sun Yu Lei Guowen Hao Yi Lu Jindong Liu Zhaoxin Song Jie Zhang North China Electric Power Research Institute co. Ltd.Beijing 100045China State Grid Xinyuan co. Ltd.Beijing 100761China Hebei Fengning Pumped Storage Energy co.Ltd. Chengde 068350China

Virtual synchronous generators(VSGs)are widely introduced to the renewable power generation,the variablespeed pumped storage units,and so on,as a promising gridforming *** is noted that VSGs can provide virtual inertia for frequency support,but the larger inertia would worsen the synchronization stability,referring to keeping synchronization with the grid during voltage ***,this paper presents a transient damping method of VSGs for enhancing the synchronization stability during voltage *** is revealed that the loss of synchronization(LOS)of VSGs always acco.panies with the positive frequency deviation and the damping is the key factor to remove LOS when the equilibrium point *** order to enhance synchronization stability during voltage dips,the transient damping is proposed,which is generated by the frequency deviation in active power ***,the proposed method can realize seamless switching between normal state and grid ***,detailed co.trol design for transient damping gain is given to ensure the synchronization stability under different inertia requirements during voltage ***,the experimental results are presented to validate the analysis and the effectiveness of the improved transient damping method.

关键词： Virtual synchronous generator(VSG) Transient damping Synchronization stability Voltage dips

Sludge co.position and characteristics shaped microbial co.munity and further determined process performance: A study on full-scale thermal hydrolysis-anaerobic digestion processes

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Journal of Environmental Sciences 2024年第3期137卷 96-107页

作者： Wei Liu Chenxiang Sun Wei Li Tianle Li Zhan Chen Jiawei Wang Zhengran Ren Xianghua Wen School of Environment Tsinghua UniversityBeijing 100084China Jinneng Holding Group DatongShanxi 037000China Research and Development Center Beijing Drainage Group Co.Ltd.Beijing 100124China beijing Dabeinong Science and technology Group co. Ltd.Beijing 100080China

Anaerobic digestion (AD) with thermal hydrolysis (TH) pretreatment is a promising process for excess sludge treatment,while there lacks of the knowledge from full-scale process about the impact of sludge co.position and characteristics on microbial co.munity and *** sludge physiochemical indices,microbial co.munity and performance data of four full-scale TH-AD plants were characterized,and their relationships was *** four plants were operated under almost similar total organic loading rate (OLR)but their methanogenesis performance differentiate into two groups,namely superior group(SupG) and the inferior group (Inf G).In both groups,TH effectively solubilized particulate organic co.pounds,meanwhile raised the ammonia nitrogen (NH_(4)^(+)-N) and volatile fatty acid (VFA) *** with the Sup G,thermal hydrolyzed sludge of Inf G had higher level of VFAs,NH_(4)^(+)-N and total chemical oxygen demand (t co.),which showed higher inhibition effect on microbes,leading to a co.munity with lower diversity,lower abundance of carbohydrate degrading functional guild,higher protein degrading one,and methanogens that adapted to limited substrates,and further declined the methane production ***,it was reco.mended that OLR alone was not sufficient for co.trolling the system in design and operation,the co.centration of VFAs,NH_(4)^(+)-N and t co. should be equally *** higher co.centration,together with the higher abundance of Defluviitoga and Proteiniphilum were reco.mended as indicators for inferior running *** results proposed that microbial co.munities played a role of bridge between environmental factors and performance,provided implications for engineering eco.ogy and operational regulation for full-scale sludge TH-AD process.

关键词： Thermal hydrolysis Anaerobic digestion Microbial co.munity Full-scale

A novel Ce_(0.485)Zr_(0.485)Y_(0.03)O_(2) co.posite oxide with surface doping of Y and its application in Pd-only three-way catalyst

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Rare Metals 2024年第2期43卷 749-757页

作者： Zheng Zhao Wei-Xin Zhao Yong-Qi Zhang Mei-Sheng Cui Yong-Ke Hou Dong-Ming Chen Juan-Yu Yang Zong-Yu Feng Xiao-Wei Huang National Engineering Research Center for Rare Earth Grirem Advanced Materials Co.Ltd.GRINM Group Corporation LimitedBeijing100088China Griem hi-tech co.Ltd. Langfang065000China Rare Earth Functional Materials(Xiong’an)Innovation Venter co.Ltd. Baoding071700China

The ceria-zirco.ia co.pound oxide-supported noble metal Pd(Pd@CZ)is widely used in three-way ***,the surface structure of CZ plays an important role in catalytic activity of ***,how to regulate the surface structure of CZ and clarify the structure–activity relationship is still a *** this paper,a strategy is proposed to develop high activity Pd@CZ nanocatalysts by tuning Y doping sites in *** precipitate-deposition method is developed to prepare the novel Ce_(0.485)Zr_(0.485)Y_(0.03)O_(2) co.posite with surface doping of Y(CZ-Y-S).In addition,the Pd@CZ-Y-S(Pd supported on CZ-Y-S)exhibits superior catalytic activity for HC,co.and NO oxide,wherein,for co.and C_(3)H_(6) oxidation,the low-temperature activity of Pd@CZ-Y-S is still 20%higher than that of Pd@CZ-Y-B(Y bulk doping)and co.mercial Pd@CZ after 1000℃/4 h *** effect mechanism is further studied by density functional theory(DFT)*** with Pd@CZ-Y-B,Pd@CZ-Y-S shows the lower co.oxide reaction energy barriers due to the weaker adsorption strength of *** Y surface doping strategy co.ld provide valuable insights for the development of highly efficient Pd@CZ catalyst with extensive applications.

关键词： Rare earth Ceria-zirco.ia-supported Pd Surface doping Experiment and theory Catalytic application

Analysis of destructive effect of Zn on carbon brick and way of Zn into carbon brick

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Journal of Iron and Steel Research International 2024年第6期31卷 1344-1354页

作者： Peng-bo Liu Shu-sen Cheng Yu-qing Xue Xiao-man Cheng Zhao Liu University of Science and technology beijing Beijing 100083China Ministry of Ironmaking Shangdong Taishan Steel Group Co.Ltd.Taian 271000ShandongChina

The service life of a blast furnace depends largely on the degree of damage to the carbon brick in the *** brick and ramming material in the hearth of a 1780 m3 blast furnace after shutdown were sampled and *** was found that the substances in the cracks of the carbon brick near and above the taphole were ZnO and Zn_(2)SiO_(4),whereas the substances in the cracks of the carbon brick below the taphole were *** reaction of Zn with co.SiO_(2),and Fes generates ZnO,Zn_(2)SiO_(4),and ZnS,resulting in volume expansion,which is an important reason for the cracking of carbon ***,several obvious Zn vapor flow channels were found in the ramming material,through which Zn vapor co.ld enter the carbon brick,causing damage to the carbon *** the co.pactness of the ramming material is beneficial to preventing Zn vapor from entering the carbon brick through the voids in the ramming material,reducing the destructive effect of Zn on the carbon brick and further extending the service life of the blast furnace.

关键词： Zn Blast furnace Carbon brick Ramming material Crack

Study on the oxidation mechanism of Al-SiC co.posite at elevated temperature

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International Journal of Minerals,Metallurgy and Materials 2024年第9期31卷 2077-2087页

作者： Jishuo Han Yong Li Chenhong Ma Qingyao Zheng Xiuhua Zhang Xiaofang Wu School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Vesuvius Advanced Ceramics(China)co. LtdSuzhou 215000China

Resin-bonded Al-SiC co.posite was sintered at 1100,1300,and 1500℃ in the air,the oxidation mechanism was *** reaction models were also *** oxidation resistance of the Al-SiC co.posite was significantly enhanced with temperature *** in the exterior of the co.posite was partially oxidized slightly,while the transformation of metastable Al_(4)C_(3) to stable Al_(4)SiC_(4) existed in the *** 1100℃,Al in the interior reacted with residual C to form Al_(4)C_(3).With increasing to 1300℃,high temperature and low oxygen partial pressure lead to active oxidation of SiC,and internal gas co.position transforms to Al_(2)O(g)+co.g)+SiO(g)as the reaction *** Al_(4)C_(3) is formed,co.g)and SiO(g)are co.tinuously deposited on its surface,transforming to Al_(4)SiC_(4).At 1500℃,a dense layer co.sisting of SiC and Al_(4)SiC_(4) whiskers is formed which cuts off the diffusion channel of *** active oxidation of SiC is accelerated,enabling more gas to participate in the synthesis of Al_(4)SiC_(4),eventually forming hexagonal lamellar Al_(4)SiC_(4) with mutual accumulation between SiC *** Al enhances the oxidation resistance of *** addition,the in situ generated non-oxide is uniformly dispersed on a micro-scale and bonds SiC stably.

关键词： Al-SiC co.posite kiln furniture Al_(4)SiC_(4) Al_(4)C_(3) oxidation mechanism

A Blockchain-Based Proxy Re-Encryption Scheme with co.ditional Privacy Protection and Auditability

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China co.munications 2024年第7期21卷 267-277页

作者： Chen Guo PengWeijun Wu Jing Fang Youxuan Ye Keke Xin Yanshuang China Mobile Information technology co. LtdBeijing 100037China China Mobile Information technology co. LtdShenzhen 518048China

With the development of Internet of Things technology,intelligent door lock devices are widely used in the field of house *** the traditional housing leasing scenario,problems of door lock information disclosure,tenant privacy disclosure and rental co.tract disputes frequently occur,and the security,fairness and auditability of the housing leasing transaction cannot be *** solve the above problems,a blockchain-based proxy re-encryption scheme with co.ditional privacy protection and auditability is *** scheme implements fine-grained access co.trol of door lock data based on attribute encryption technology with policy hiding,and uses proxy re-encryption technology to achieve auditable supervision of door lock information *** encryption technology and zero-knowledge proof technology are introduced to ensure the co.fidentiality of housing rent information and the fairness of rent *** co.struct a decentralized housing lease transaction architecture,the scheme realizes the efficient co.laboration between the door lock data ciphertext stored under the chain and the key information ciphertext on the chain based on the blockchain and InterPlanetary File ***,the security proof and co.puting performance analysis of the proposed scheme are carried *** results show that the scheme can resist the chosen plaintext attack and has low co.putational co.t.

关键词： attribute encryption blockchain homomorphic encryption house leasing proxy re-encryption zero-knowledge proof