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Long-term effects of electrochemical realkalization on carbonated concrete

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Frontiers of Structural and Civil Engineering 2020年第1期14卷 127-137页

作者： Peng ZHU Ji ZHANG Wenjun qu College of Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Performance Evolution and Control for Engineering Structures Shanghai 200092China

The long-term effects of electrochemical realkalization on carbonated reinforced concrete with a W/C ratio of 0.65 were *** out of 16 carbonated specimens had been subjected to realkalization seven years ago,and the alkalinity of the concrete,the electrochemical characters(corrosion current density and potential)of the specimens and the corrosion conditions of the steel bars were *** of different specimens and also at different time(4,10,13 months and 7 years after realkalization)were *** to the phenolphthalein and pH meter test,the alkalinity of the concrete had disappeared after seven *** on the potentiodynamic polarization test,various corrosion conditions had developed on the steel bars,which was verified by visual *** bars were in the depassivated state,and their corrosion current densities increased significantly after seven *** developed in some of the specimens,and the diverse compactness of concrete and excessive current of realkalization were considered to be possible *** effects of the realkalization treatment vanished after seven years.

关键词： realkalization concrete carbonation polarization curve corrosion

Relation Between Strength and Hardness of High-Entropy Alloys

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Acta Metallurgica Sinica(English Letters) 2021年第11期34卷 1461-1482页

作者： Xiaojuan Fan Ruitao qu Zhefeng Zhang Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Nano Science and Technology Institute University of Science and Technology of ChinaSuzhou 215132China School of Materials Science and Engineering Northwestern Polytechnical UniversityXi'an 710072China

High-entropy alloys(HEAs)are composed of multiple principal elements and exhibit not only remarkable mechanical properties,but also promising potentials for developing numerous new *** fully realize such potentials,highthroughput preparation and characterization technologies are especially useful;thereby,the fast evaluations of mechanical properties will be urgently *** the relation between strength and hardness is of significance for quickly predicting the strength of materials through simple hardness ***,up to now the strength-hardness relation for HEAs is still a *** this work,the relations between tensile or compressive strength and Vickers hardness of various HEAs with hundreds of compositions at room temperature are investigated,and finally,the solution for estimating the strengths of HEAs from their hardness values is *** for hundreds of different HEAs were extracted from studies reported in the period from 2010 to *** results suggested that the well-known three-time relation(i.e.,hardness equals to three times the magnitude of strength)works for nearly all HEAs,except for a few brittle HEAs which show quite high hardness but low strength due to early ***,for HEAs with different phase structures,different strengths should be applied in using the 3-time relation,i.e.,yield strength for low ductility body-centered cubic(BCC)HEAs and ultimate strength for highly plastic and work-hardenable face-centered cubic(FCC)*** for dual-phase or multi-phase HEAs,similar 3-time relations can be also *** present approach sheds light on the mechanisms of hardness and also provides useful guidelines for quick estimation of strength from hardness for various HEAs.

关键词： High-entropy alloys Vickers hardness Strength Plasticity

A Review on the Mullins Effect in Tough Elastomers and Gels

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Acta Mechanica Solida Sinica 2024年第2期37卷 181-214页

作者： Lin Zhan Shaoxing qu Rui Xiao MOE Key Lab of Disaster Forecast and Control in Engineering College of Mechanics and Construction EngineeringJinan UniversityGuangzhou510632China State Key Laboratory of Fluid Power and Mechatronic System Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering MechanicsZhejiang UniversityHangzhou310027China

Tough elastomers and gels have garnered broad research interest due to their wide-ranging potential ***,during the loading and unloading cycles,a clear stress softening behavior can be observed in many material systems,which is also named as the Mullins *** this work,we aim to provide a complete review of the Mullins effect in soft yet tough materials,specifically focusing on nanocomposite gels,double-network hydrogels,and multi-network *** first revisit the experimental observations for these soft *** then discuss the recent developments of constitutive models,emphasizing novel developments in the damage mechanisms or network *** phenomenological models will also be briefly *** attention is then placed on the anisotropic and multiaxial modeling *** is demonstrated that most of the existing models fail to accurately predict the multiaxial data,posing a significant challenge for developing future anisotropic models tailored for tough gels and elastomers.

关键词： Mullins effect Double-network hydrogels Nanocomposite gels Multi-network elastomers Anisotropic damage model Multiaxial model

Towards“General Purpose”Brain-Inspired Computing System

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Tsinghua Science and Technology 2021年第5期26卷 664-673页

作者： Youhui Zhang Peng qu Weimin Zheng the Department of Computer Science and Technology Tsinghua UniversityBeijing 100084China

Brain-inspired computing refers to computational models,methods,and systems,that are mainly inspired by the processing mode or structure of brain.A recent study proposed the concept of"neuromorphic completeness"and the corresponding system hierarchy,which is helpful to determine the capability boundary of brain-inspired computing system and to judge whether hardware and software of brain-inspired computing are compatible with each *** a position paper,this article analyzes the existing brain-inspired chips design characteristics and the current so-called"general purpose"application development frameworks for brain-inspired computing,as well as introduces the background and the potential of this ***,some key features of this concept are presented through the comparison with the Turing completeness and approximate computation,and the analyses of the relationship with"general-purpose"brain-inspired computing systems(it means that computing systems can support all computable applications).In the end,a promising technical approach to realize such computing systems is introduced,as well as the on-going research and the work *** believe that this work is conducive to the design of extensible neuromorphic complete hardware-primitives and the corresponding *** this basis,it is expected to gradually realize"general purpose"brain-inspired computing system,in order to take into account the functionality completeness and application efficiency.

关键词： brain-inspired computing neuromorphic computing computational completeness hardware/software decoupling system hierarchy

A Novel Fractional Plastic Damage Model for quasi-brittle Materials

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Acta Mechanica Solida Sinica 2021年第5期34卷 706-717页

作者： Peng-Fei qu Qi-Zhi Zhu Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai UniversityNanjing210098China College of Civil and Transportation Engineering Hohai UniversityNanjing210098China

In this work,a novel constitutive model is developed within the framework of fractional plasticity to delineate the coupling between inelastic deformation and damage of quasi-brittle *** with the common challenge of determining plastic flow direction,we resort herein to the Riemann–Liouville definition of fractional derivatives,instead of introducing an additional plastic *** pre-peak hardening behavior is described using an exponential function,while the post-peak softening response is viewed as the consequence of material *** describing damage evolution,a damage criterion is constructed in terms of plastic volume dilation related to micro-crack *** is conducive to supply a new insight for describing the complex influence of the non-orthogonality of plastic flow on damage *** numerical applications,a semi-implicit return mapping algorithm is *** predictive performance of the model is evaluated by comparing numerical simulations with experimental data under various loading paths.

关键词： quasi-brittle materials Fractional plasticity Damage Dilatancy Numerical algorithm

Comparison of Gatekeeping and Non-gatekeeping Designs in a Service System with Delay-sensitive Customers

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Journal of Systems Science and Systems Engineering 2021年第2期30卷 125-150页

作者： Wenhul Zhou Xiuzhang Li qu Qian School of Business Administration South China University of TechnologyGuangzhou 510641China School of Business Singapore University of Social SciencesSingapore 599494Singapore

This paper is motivated by a concern in China's current medical practice in which patients can bypass the primary care and seek secondary care *** employ a queueing approach to examine two settings,*** gatekeeping and non-gatekeeping settings,in a service system consisting of two types of service provider-one with basic skills(C-H),*** hospital,and the other with advanced skills(AAA-H),*** *** are heterogeneous with respect to service *** C-H can only serve customers with a complexity level of service requirement lower than the cure threshold,while the AAA-H can serve all *** aim to analyze the social planner's capacity decision for the C-H in both settings and assess the relative merit of each setting with respect to total social welfare,*** sum of customer benefits net of customer delay costs and service providers7 operating *** findings show that when the C-H's capacity is exogenous,the gatekeeper setting is preferable if the capacity of the C-H is in the intermediate range because customers'self-selection behavior gives rise to negative *** the C-H's capacity is optimized by the social planner,the non-gatekeeping setting is preferable if the capacity of the AAA-H is large or the cure threshold is high,because customers'self-selection behavior as well as the investment in the C-H's capacity can result in a better distribution of demand among the two service *** gatekeeping setting is preferable if the cure threshold is low because it is economical for the social planner to invest in a large capacity in the C-H to serve all *** also show numerically the conditions under which the two settings can achieve the first-best solution.

关键词： Customer delay sensitivity gatekeeper service capacity cure fraction total social cost

A discretely damped SDOF model for the rocking response of freestanding blocks

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Earthquake Engineering and Engineering Vibration 2022年第3期21卷 729-740页

作者： Liu Hanquan Huang Yuli qu Zhe Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationKey Laboratory of Earthquake Disaster MitigationMinistry of Emergency ManagementHarbin 150080China Sanhe 065201China Arup San FranciscoCA 94105USA

This paper presents a single-degree-of-freedom(SDOF)constitutive model for assessing the performance of freestanding block contents of *** model incorporates a bespoke damper to account for energy dissipation associated with *** is advantageous in its direct correlation,via energy conservation,to the restitution coefficient for impact during rocking.A comparative study with the existing SDOF rocking models shows that the proposed model significantly improves the accuracy of free-rocking simulations,in which inherent damping predominantly affects *** provides a promising and efficient tool for computationally intensive performance evaluation of nonstructural components.

关键词： contents rigid block equivalent viscous damping free rocking forced rocking single-degree-of-freedom system

Heavy metal accumulation characteristics and physiological response of Sabina chinensis and Platycladus orientalis to atmospheric pollution

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Journal of Environmental Sciences 2022年第2期34卷 192-201页

作者： Ning Cui Laiye qu Gang Wu State Key Laboratory of Urban and Regional Ecology Research Center for Eco-environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China

Heavy metal(Cu,Mn,Zn,Pb,and Cd)concentrations were measured in the leaves of Sabina chinensis and Platycladus orientalis collected from urban,suburban,and rural sites in Tianjin,*** pigment contents,reactive oxygen species content,malondialdehyde(MDA)content and antioxidant enzyme activity were investigated,providing physiological response *** comparison of the sites revealed that urbanization significantly influenced the heavy metal concentrations in both plant *** the rural site,both plant leaves exhibited the lowest heavy metal *** highest Cu,Mn,and Zn concentrations were found in *** leaves from the urban site;the highest Pb and Cd concentrations were found in *** leaves from the urban *** results indicate that the urban site contained larger heavy metal concentrations in the plant leaves that may reflect the anthropogenic emission *** is also found that *** may be used to monitor airborne heavy metal pollution because it is highly quick response to heavy metals,while *** may be used for mitigation due to its high *** results of this study can contribute to the development of monitoring and environmental management plans by providing information on sensitive and resistant tree species for city greening in North China.

关键词： Atmospheric heavy metal pollutions Sabina chinensis Platycladus orientalis Physiological responses

Wavelet-based classification and influence matrix analysis method for the fast discrimination of Chinese herbal medicines according to the geographical origins with near infrared spectroscopy

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Journal of Innovative Optical Health Sciences 2014年第4期7卷 21-31页

作者： Wenlong Li Haibin qu Pharmaceutical Informatics Institute Zhejiang University No.866 Yuhangtang Road Hangzhou310058P.R.China

A discriminant analysis technique using wavelet transformation(WT)and influence matrixanalysis(CAIMAN)method is proposed for the near infrared(NIR)spectroscopy *** the proposed methodology,NIR spectra are decomposed by WT for data com-pression and a forward feature selection is further employed to extract the relevant informationfrom the wavelet coefficients,reducing both classification errors and model ***-CAIMAN(D-CAIMAN)method is utilized to build the classification model inwavelet domain on the basis of reduced wavelet coefficients of spectral *** spectradata set of 265 salviae miltiorrhizae radia samples from 9 different geographical origins is usedas an example to test the classification performance of the *** a comparison,k-nearest neighbor(KNN),linear discriminant analysis(LDA)and quadratic discriminant analysis(QDA)methods are also employed.D-CAIMAN with wavelet-based feature selection(WD-CAIMAN)method shows the best performance,achieving the total classification rate of ioo%in both cross-validation set and prediction *** is worth noting that the WD-CAIMANclassifier also shows improved sensitivity,selectivity and model interpretability in ***.

关键词： Discriminant analysis near infrared spectroscopy Chinese herbal medicines variable selection wavelet analysis