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Valence electron structure and hydrogen storage property of LaNi_-4Co

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Rare Metals 2015年第4期34卷 259-266页

作者： lei zhang Shi-Chun Li School of Electromechanical Automobile Engineering Yantai University Key Laboratory of Advanced Manufacturing and Control Technology in Universities of Shandong Materials Department College of Electromechanical Engineering China University of Petroleum

In the present study, two models of atom occupation in LaNi4Co were put forward and corresponding valence electron structures （VESs） of these two models were investigated according to empirical electron theory （EET） of solids and molecules. Results demonstrate that the VES-concerned hardness factor （FH） of LaNi4Co is lower than that of LaNi5, so LaNi4Co has lower hardness, higher plasticity and improved anti-pulverization ability. In the mean time, the difference of the equilibrium hydrogen pressure between LaNiaCo and LaNi5 was analyzed in the electronic level. The analysis shows that the strength of the weakest bond net in octahedron lattice interstices of LaNi4Co is much lower than that in LaNis; consequently, LaNi4Co＇s bond net easily deforms to accommodate hydrogen so that LaNi4Co has lower equilibrium hydrogen pressure in comparison with LaNis. The results can provide some theory guide on the design of hydrogen storage alloys.

关键词： Alloys Computer modeling and simulation Electronic structure Mechanical properties

A Review of Rotating Stall in Vaneless Diffuser of Centrifugal Compressor

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Journal of Thermal Science 2020年第2期29卷 323-342页

作者： zhang lei HE Ruiyang WANG Songling zhang Qian School of Energy Power&Mechanical EngineeringNorth China Electric Power UniversityBaoding 071003China

At present, off-design centrifugal compressor suffers from great instabilities, such as rotating stall and surge, which lead to work failure, strong pressure fluctuations, and violent vibrations of the entire system. One cause of these instabilities is the rotating stall occurring in vaneless diffuser. In this review, recent researches on rotating stall of vaneless diffuser in centrifugal compressor are reviewed, and its inductive mechanism and characteristic description are emphatically introduced. In vaneless diffuser, the rotating stall starts up and fully develops under non-design conditions with the characteristic of increasing pressure fluctuation amplitude. The negative effects of rotating stall include reverse flow and vortex, both of which have significant effects on the instability of centrifugal compressors. Some improvement methods of rotating stall are also introduced, and a lot of examples are given. Finally, some suggestions and discussions are put forward for the future work.

关键词： centrifugal compressor vaneless diffuser rotating stall reverse flow pressure fluctuation

Non-noble metal-based catalysts for acetylene semihydrogenation:from thermocatalysis to sustainable catalysis

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Science China Chemistry 2023年第7期66卷 1963-1974页

作者： lei zhang Jin Lin Zhenpeng Liu Jian zhang Research&Development Institute of Northwestern Polytechnical University in Shenzhen School of Chemistry and Chemical EngineeringNorthwestern Polytechnical UniversityXi’an 710129China State Key Laboratory of Solidification Processing and School of Materials Science and Engineering Northwestern Polytechnical UniversityXi’an 710072China

Selective semihydrogenation of acetylene in raw olefin streams to ethylene is a key industrial reaction to produce polymer-grade feeds for the manufacture of corresponding *** currently used process in industry is the thermocatalytic acetylene semihydrogenation with pressurized hydrogen and Pd-based catalysts at relatively high *** high cost of Pd urgently desires the design of non-noble metal-based ***,non-noble metal-based catalysts commonly require much higher reaction temperatures than Pd-based catalysts because of their poor intrinsic ***,aiming at increasing economic efficiency and sustainability,various strategies are explored for developing non-noble metal-based catalysts for thermocatalytic and green acetylene semihydrogenation *** this review,we systematically summarize the recent advances in catalytic technology from thermocatalysis to sustainable alternatives,as well as corresponding regulation strategies for designing high-performance non-noble metal-based *** crucial factors affecting catalytic performance are discussed,and the fundamental structure-performance correlation of catalysts is ***,we emphasize current challenging issues and future perspectives for acetylene *** review will not only promote the rapid exploration of non-noble metal-based catalysts for acetylene semihydrogenation,but also advance the development of sustainable processes like electrocatalysis and photocatalysis.

关键词： acetylene semihydrogenation non-noble metal-based catalysts thermocatalysis sustainable catalysis

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A Survey on Negative Transfer

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IEEE/CAA Journal of Automatica Sinica 2023年第2期10卷 305-329页

作者： Wen zhang Lingfei Deng lei zhang Dongrui Wu the Key Laboratory of the Ministry of Education for Image Processing and Intelligent Control School of Artificial Intelligence and AutomationHuazhong University of Science and TechnologyWuhan 430074China IEEE the School of Microelectronics and Communication Engineering Chongqing UniversityChongqing 400044China

Transfer learning(TL)utilizes data or knowledge from one or more source domains to facilitate learning in a target *** is particularly useful when the target domain has very few or no labeled data,due to annotation expense,privacy concerns,***,the effectiveness of TL is not always *** transfer(NT),i.e.,leveraging source domain data/knowledge undesirably reduces learning performance in the target domain,and has been a long-standing and challenging problem in *** approaches have been proposed in the literature to address this ***,there does not exist a systematic *** paper fills this gap,by first introducing the definition of NT and its causes,and reviewing over fifty representative approaches for overcoming NT,which fall into three categories:domain similarity estimation,safe transfer,and NT *** areas,including computer vision,bioinformatics,natural language processing,recommender systems,and robotics,that use NT mitigation strategies to facilitate positive transfers,are also ***,we give guidelines on NT task construction and baseline algorithms,benchmark existing TL and NT mitigation approaches on three NT-specific datasets,and point out challenges and future research *** ensure reproducibility,our code is publicized at https://***/chamwen/NT-Benchmark.

关键词： Domain adaptation domain similarity negative transfer positive transfer transfer learning

Error Estimate for Semi-implicit Method of Sphere-Constrained High-Index Saddle Dynamics

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Chinese Annals of Mathematics,Series B 2023年第5期44卷 765-780页

作者： lei zhang Pingwen zhang Xiangcheng ZHENG Beijing International Center for Mathematical Research Center for Machine Learning ResearchCenterfor Quantitative BiologyPeking UniversityBeijing 100871China School of Mathematics and Statistics Wuhan UniversityWuhan 430072China School of MathematicalSciences Laboratory of Mathematics and Applied MathematicsPeking UniversityBeijing 100871China School of Mathematics Shandong UniversityJinan 250100China

The authors prove error estimates for the semi-implicit numerical scheme of sphere-constrained high-index saddle dynamics,which serves as a powerful instrument in finding saddle points and constructing the solution landscapes of constrained systems on the high-dimensional *** to the semi-implicit treatment and the novel computational procedure,the orthonormality of numerical solutions at each time step could not be fully employed to simplify the derivations,and the computations of the state variable and directional vectors are coupled with the retraction,the vector transport and the orthonormalization procedure,which significantly complicates the *** address these issues to prove error estimates for the proposed semi-implicit scheme and then carry out numerical experiments to substantiate the theoretical findings.

关键词： Saddle point Constrained saddle dynamics Solution landscape Semiimplicit Numerical analysis

Information mining and similarity computation for semi-/un-structured sentences from the social data

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Digital Communications and Networks 2021年第4期7卷 518-525页

作者： Peiying zhang Xingzhe Huang lei zhang College of Computer Science and Technology China University of Petroleum(East China)Qingdao266580China Petroleum Engineering Technology Research Institute Shengli OilfieldSinopecDongying257000China

In recent years,with the development of the social Internet of Things(IoT),all kinds of data accumulated on the *** data,which contain a lot of social information and ***,these data are rarely fully analyzed,which is a major obstacle to the intelligent development of the social *** this paper,we propose a sentence similarity analysis model to analyze the similarity in people’s opinions on hot topics in social media and news *** of these data are unstructured or semi-structured sentences,so the accuracy of sentence similarity analysis largely determines the model’s *** the purpose of improving accuracy,we propose a novel method of sentence similarity computation to extract the syntactic and semantic information of the semi-structured and unstructured *** mainly consider the subjects,predicates and objects of sentence pairs and use Stanford Parser to classify the dependency relation triples to calculate the syntactic and semantic similarity between two ***,we verify the performance of the model with the Microsoft Research Paraphrase Corpus(MRPC),which consists of 4076 pairs of training sentences and 1725 pairs of test sentences,and most of the data came from the news of social *** simulations demonstrate that our method outperforms other state-of-the-art methods regarding the correlation coefficient and the mean deviation.

关键词： Sentence similarity computation Information mining and computation Social data Internet of things Type of sentence pairs

Vitrification cryopreservation of ligaments based on zwitterionic betaine

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Chinese Journal of Chemical Engineering 2024年第8期72卷 1-9页

作者： Liming zhang Xinmeng Liu Haoyue Li lei zhang Department of Biochemical Engineering Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering(MOE)School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Ligament cryopreservation enables a prolonged shelf life of allogeneic ligament grafts,which is fundamentally important to ligament ***,conventional cryopreservation techniques fail to eliminate the damage caused by ice crystal growth and the toxicity of cryopreservation agents(CPAs).Here,we report a novel CPA vitrification formulation primarily composed of betaine for ligament *** optimization was conducted on the methods for vitrification and rewarming,as well as the loading and unloading conditions,based on the critical cooling rate(CCR),critical warming rate(CWR),and permeation properties of the *** biomechanical and histological level tests,we demonstrate the superior performance of our method in ligament *** 30 days of vitrification cryopreservation,parameters such as the Young's modulus,tensile stress,denaturation temperature,and glycosaminoglycans content of the ligament remained essentially *** work pioneers the application of ice-free cryopreservation for ligament and holds great potential for improving the long-term storage of ligament,providing valuable insights for future cryopreservation technique development.

关键词： Ligament Betaine Vitrification Cryopreservation

Sichuan dialect speech recognition with deep LSTM network

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Frontiers of Computer Science 2020年第2期14卷 378-387页

作者： Wangyang YING lei zhang Hongli DENG Machine Intelligence Laboratory College of Computer ScienceSichuan UniversityChengdu 610065China Education and Information Technology Center China West Normal UniversityNanchong 637002China

In speech recognition research,because of the variety of languages,corresponding speech recognition systems need to be constructed for different *** in a dialect speech recognition system,there are many special words and oral language *** addition,dialect speech data is very ***,constructing a dialect speech recognition system is *** paper constructs a speech recognition system for Sichuan dialect by combining a hidden Markov model(HMM)and a deep long short-term memory(LSTM)*** the HMM-LSTM architecture,we created a Sichuan dialect dataset and implemented a speech recognition system for this *** with the deep neural network(DNN),the LSTM network can overcome the problem that the DNN only captures the context of a fixed number of information ***,to identify polyphone and special pronunciation vocabularies in Sichuan dialect accurately,we collect all the characters in the dataset and their common phoneme sequences to form a ***,this system yields a 11.34%character error rate on the Sichuan dialect evaluation *** far as we know,it is the best performance for this corpus at present.

关键词： speech recognition Sichuan dialect HMMDNN HMM-LSTM Sichuan dialect lexicon

Digital Twin Modeling Enabled Machine Tool Intelligence:A Review

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 29-54页

作者： lei zhang Jianhua Liu Cunbo Zhuang School of Mechanical Engineering Tianjin University of CommerceTianjin 300134China Laboratory of Digital Manufacturing School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 10081China

Machine tools,often referred to as the“mother machines”of the manufacturing industry,are crucial in developing smart manufacturing and are increasingly becoming more *** twin technology can promote machine tool intelligence and has attracted considerable research ***,there is a lack of clear and systematic analyses on how the digital twin technology enables machine tool ***,digital twin modeling was identified as an enabling technology for machine tool intelligence based on a comparative study of the characteristics of machine tool intelligence and digital *** review then delves into state-of-the-art digital twin modelingenabled machine tool intelligence,examining it from the aspects of data-based modeling and mechanism-data dual-driven ***,it highlights three bottleneck issues facing the *** these problems,the architecture of a digital twin machine tool(DTMT)is proposed,and three key technologies are expounded in detail:Data perception and fusion technology,mechanism-data-knowledge hybrid-driven digital twin modeling and virtual-real synchronization technology,and dynamic optimization and collaborative control technology for multilevel ***,future research directions for the DTMT are *** work can provide a foundation basis for the research and implementation of digital-twin modeling-enabled machine tool intelligence,making it significant for developing intelligent machine tools.

关键词： Machine tool Digital twin Smart manufacturing Synchronization