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Influence of initial microstructure and grain size on transformation of bainite to austenite in large size forgings

Journal of Iron and Steel Research International 2018年第5期25卷 554-562页

作者： emna ben fredj Hadi Ghasemi Nanesa Mohammad Jahazi Jean-benoit Morin Department of Mechanical Engineering Ecole deTechnologie Superieure Montreal QC H3C 1K3 Canada Finkl Steel-Sorel St-Joseph-de-Sorel QC J3R 3M8 Canada

The kinetics of austenite formation in the surface and center regions of a 40 t forged ingot of a high-strength medium- carbon low-alloy steel was studied using high-resolution dilatometry. The starting microstructures from the surface or center regions had different proportions of bainite and residual austenite as well as different prior austenite grain sizes. Two heating rates representing the actual heating rates in the surface （5℃ s -1） and center regions （0.5℃ s -1） of large size forged blocks were utilized. Dilatometric curves revealed only one transformation step of austenite formation at both heating rates independent of grain size or proportion of phases. Optical microscopy, field emission gun scanning electron microscopy and X-ray diffraction were used to study microstructure evolution and confirm the results obtained by dilatometry. The kinetic parameters for austenite formation were determined from the dilatometry data by Johnson-Mehl- Avrami-Kolmogorov （JMAK） equation. The JMAK coefficients were determined for each condition of the investigated steels. The calculations indicated that the nucleation and growth of austenite in the surface region were accelerated more than 10,000 times due to a significantly smaller average prior austenite grain size, stability of initial retained austenite, and accumulation of coarse carbides at the surface. The results were discussed in the framework of classical nucleation and growth theories using the kinetic parameters for austenite formation.

关键词： Large size ingot Medium-carbon low-alloy steel Initial microstructure Grain size Austenite formation

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Geochemistry, mineral paragenesis and geothermal conditions of oreforming fluids from the Ain El Bey Cu–Fe deposit: potential occurrence of native gold and precious metal traces (North African orogenic belt, Northern Tunisia)

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Acta Geochimica 2024年第2期43卷 366-384页

作者： Rania ben Aissa Wiem ben Aissa Said Tlig Lassaad ben Aissa Abdessalem ben Haj Amara Faculty of Science of Bizerte University of Carthage7021 ZarzounaBizerteTunisia Laboratoire de Recherche Ressources Materiaux et EcosystemesUniversity of Carthage7021 ZarzounaBizerteTunisia Department of Geology University Claude Bernard Lyon 169622 VilleurbanneFrance Faculty of Science of Tunis University of Tunis-El ManarRommana1068 TunisTunisia

The Ain El Bey abandoned mine, in North-West Tunisia, fits into the geodynamic context of the European and African plate boundary. Ore deposit corresponds to veins and breccia of multiphase Cu–Fe-rich mineralization related to various hydrothermal fluid circulations. Petromineralogical studies indicate a rich mineral paragenesis with a minimum of seven mineralization phases and, at least, six pyrite generations. As is also the case for galena and native silver, native gold is observed for the first time as inclusion in quartz which opens up, thus, new perspectives for prospecting and evaluating the potential for noble metals associated with the mineralization. Scanning Electron Microscope--Energy Dispersive Spectroscopy and Transmission electron microscopy analyses show, in addition, a large incorporation of trace elements, including Ag and Au, in mineral structures such as fahlores(tetrahedrite-tennantite) and chalcopyrite ones. The mineral/mineral associations, used as geothermometers, gave estimated temperatures for the mineralizing fluids varying from 254 to 330 ℃ for phase Ⅲ, from 254 to 350 ℃ for phase Ⅳ, and from 200 to 300 ℃ for phases Ⅴ and Ⅵ. The seventh and last identified mineralization phase, marked by a deposit of native gold, reflects a drop in the mineralizing fluid’s temperature(< 200 ℃) compatible with boiling conditions. Such results open up perspectives for the development of precious metal research and the revaluation of the Cu–Fe ore deposit at the Ain El Bey abandoned mine, as well as at the surrounding areas fitting in the geodynamic framework of the Africa-Europe plate boundary.

关键词： Ore-formingﬂuids Mineral geochemistry Mineral geothermometers Native silver-gold Ain El Bey Ore deposit North Tunisia

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Cooperative Target Fencing of Multiple Vehicles for a General Target with Connectivity Preservation and Collision Avoidance

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Journal of Systems Science & Complexity 2024年第1期37卷 136-151页

作者： PAN Zini CHEN ben M Department of Mechanical and Automation Engineering The Chinese University of Hong KongHong KongChina

In this paper,the authors study the cooperative target-fencing problem for n-dimensional systems and a target with a general *** using the velocity of the vehicles,a position feedback control law is proposed to fence the general target into the convex hull formed by the ***,the dynamics of each vehicle is described by a double-integrator *** potential functions are designed to guarantee connectivity preservation of the communication network and collision avoidance among the *** proposed approach can deal with a target whose trajectory is any twice continuously differentiable function of *** effectiveness of the result is verified by a numerical example.

关键词： Multi-agent systems networked systems target fencing

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Preparing lipid nanoparticles with tunable drug loading capacity and morphology via improved sequential nanoprecipitation

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Science China Chemistry 2024年第5期67卷 1373-1374页

作者： Haoran Wang ben Zhong Tang Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction Department of Chemistry.Institute of Molecular Functional MaterialsState Key Laboratory of NeuroscienceDivision of Biomedical Engineering and Division of Life ScienceThe Hong Kong University of Science and TechnologyHong Kong 999077China School of Science and Engineering Shenzhen Institute of Aggregate Science and Technology The Chinese University of Hong KongShenzhen(CUHK-Shenzhen)Shenzhen 518172China

Nanotechnology hailed as a revolutionary new technology of the 21st century, has ignited a wave of innovation across diverse fields spanning chemistry, physics, materials science,medicine, engineering, and electronics. In 2016, Nature published an article titled “The nanolight revolution is coming”, underscoring that “virus-sized particles that emit light in every color could transform applications ranging from television displays to cancer treatment”.

关键词： sized loading treatment

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Boeravinone B ameliorates allergic nasal inflammation by modulating the GATA-3/T-bet signaling pathway in a mouse model of allergic rhinitis

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Asian Pacific Journal of Tropical Biomedicine 2024年第6期14卷 245-252页

作者： ben Ye Ji-Zhe Wang Department of Otorhinolaryngology Second Hospital of Dalian Medical UniversityDalian116000China Department of Otorhinolaryngology Shandong Provincial Hospital Affiliated to Shandong First Medical UniversityJinan250000China

Objective:To evaluate the anti-allergic effect of boeravinone B against ovalbumin-induced allergic rhinitis in mice and explore its possible ***:For the induction of allergic rhinitis,mice were intraperitoneally sensitized and intranasally challenged with ovalbumin,as well as orally received various concentrations of boeravinone *** mucosal inflammation,and the levels of nitric oxide,β-hexosaminidase,IFN-γ,LTC-4,myeloperoxidase,Nrf2,HO-1,GATA-3,ROR-γ,T-bet,antioxidant parameters,and allergen-specific cytokines were ***:Boeravinone B markedly reduced ovalbumin-induced increase in the number of episodes of nasal sneezing,rubbing,and discharge,as well as the levels of IgE,IgG1,andβ-hexosaminidase(P<0.05).It also significantly reduced differential cell count,myeloperoxidase,oxide-nitrosative stress,and the levels of IL-1β,IL-4,IL-5,IL-6,IL-13,IL-17,tumor necrosis factor-α,GATA-3,and ROR-γwhile enhancing the level of ***:Boeravinone B is a potential therapeutic agent for allergic rhinitis by modulating various inflammatory mediators and immune responses.

关键词： Allergic reaction Boeravinone B Oxidative stress Inflammation Ovalbumin

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Energy-Function Based Pilot Protection Scheme for Hybrid UHVDC Transmission Applying Improved Hausdorff Distance

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 891-902页

作者： Zijiang Wang Youping Fan ben Shang Yinbiao Shu School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China Institute of Next Generation Power Systems&International Standards Wuhan UniversityWuhan 430072China CSEE IEEE

A hybrid UHVDC transmission system applying LCC as the rectifier and MMC as the inverter combines the advantages of both converter types,which makes this protection scheme more complicated.A new pilot protection scheme for a three-terminal hybrid DC transmission system applying energy functions is *** energy function for LCC is applied to MMC to derive the energy level of the hybrid ***,an improved Hausdorff distance(IHD)algorithm is proposed to detect the difference in energy levels between the normal and fault *** abrupt change in energy level is characterized by IHD change *** points at which the IHD change rate exceeds the threshold at converter stations are applied to determine the fault line and to estimate the fault *** proposed protection scheme is then verified by a simulation model of the Wudongde±800 kV three-terminal hybrid UHVDC transmission *** appropriate sampling frequency is selected for a real-time calculation,and the threshold is selected considering the effect of *** show the proposed scheme can identify and trip fault lines quickly and effectively,even for a 600Ωgrounding *** waveshape similarity algorithms are compared and *** with existing protection schemes,the proposed scheme transmits less data to improve communication speed and reliability.

关键词： Energy function Hausdorff distance pilot protection UHVDC transmission

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Organic stabilization in earthen plaster:Eco-compatible architecture and ancient techniques in Tata Somba homes

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Frontiers of Architectural Research 2024年第3期13卷 625-638页

作者： D.ben Ghida Department of Architecture University of Naples FedericoⅡNaplesItaly

The study of organic stabilization is crucial for understanding its impact on the durability and effectiveness of earthen *** natural admixtures’effects on plaster properties provides insights that aid in optimizing plaster composition and application for desired *** addition of biopolymers,known to enhance plaster performance,necessitates further investigation to understand their role in earthen plaster *** study focuses on Tata Somba homes in benin and Togo,recognized as UNESCO World Heritage *** unique architectural examples embody“architecture without architects”,relying solely on local traditional *** objective is to explore and revive Tata Somba’s ancient eco-technology for earth plaster *** shows that biopolymers’combined stabilization and application techniques can improve earthen plaster *** promising bio-stabilizers were identified,suggesting their potential as sustainable,effective options for CO_(2) mitigation in *** findings not only deepen our understanding of earthen architecture but also underscore the potential of merging traditional,eco-friendly building methods with modern scientific insights to create sustainable solutions for cultural heritage preservation and contemporary built environments.

关键词： Vernacular architecture Cultural heritage preservation Sustainable architecture Biopolymer Earth architecture Earth stabilization

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An efficient strategy enabling solution processable thermally activated delayed fluorescence emitter with high horizontal dipole orientation

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Chinese Journal of Structural Chemistry 2024年第6期43卷 4-5页

作者： Zheng Zhao ben Zhong Tang School of Science and Engineering Shenzhen Institute of Aggregate Science and TechnologyThe Chinese University of Hong KongShenzhen(CUHK-Shenzhen)Guangdong518172China

Organic light-emitting diodes(OLEDs)based on highly efficient aggregate emitters present a significant breakthrough in realizing low-cost displays and solid-state lighting,thus drawing considerable research interest i... 详细信息

关键词： emitter breakthrough dipole

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Emergence of SARS and COVID-19 and preparedness for the next emerging disease X

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Frontiers of Medicine 2024年第1期18卷 1-18页

作者： ben Hu Hua Guo Haorui Si Zhengli Shi CAS Key Laboratory of Special Pathogens and Biosafety Wuhan Institute of VirologyChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

Severe acute respiratory syndrome(SARS)and Coronavirus disease 2019(COVID-19)are two human Coronavirus diseases emerging in this century,posing tremendous threats to public health and causing great loss to lives and *** this review,we retrospect the studies tracing the molecular evolution of SARS-CoV,and we sort out current research findings about the potential ancestor of *** knowledge about SARS-CoV-2-like viruses found in wildlife,the animal susceptibility to SARS-CoV-2,as well as the interspecies transmission risk of SARS-related coronaviruses(SARSr-CoVs)are gathered ***,we discuss the strategies of how to be prepared against future outbreaks of emerging or re-emerging coronaviruses.

关键词： SARS COVID-19 coronavirus

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Adaptive Barrier-Lyapunov-Functions Based Control Scheme of Nonlinear Pure-Feedback Systems with Full State Constraints and Asymptotic Tracking Performance

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Journal of Systems Science & Complexity 2024年第3期37卷 965-984页

作者： NIU ben WANG Xiaoan WANG Xiaomei WANG Xinjun LI Tao Faculty of Electronic Information and Electrical Engineering Dalian University of TechnologyDalian 116024China School of Information Science and Engineering Shandong Normal UniversityJinan 250014China School of Mathematics Southeast UniversityNanjing 211189China School of Automation Nanjing University of Information Science and TechnologyNanjing 210044China

In this paper,the authors propose an adaptive Barrier-Lyapunov-Functions(BLFs)based control scheme for nonlinear pure-feedback systems with full state *** to the coexist of the non-affine structure and full state constraints,it is very difficult to construct a desired controller for the considered *** to the mean value theorem,the authors transform the pure-feedback system into a system with strict-feedback structure,so that the well-known backstepping method can be ***,in the backstepping design process,the BLFs are employed to avoid the violation of the state constraints,and neural networks(NNs)are directly used to online approximate the unknown packaged nonlinear *** presented controller ensures that all the signals in the closed-loop system are bounded and the tracking error asymptotically converges to ***,it is shown that the constraint requirement on the system will not be violated during the ***,two simulation examples are provided to show the effectiveness of the proposed control scheme.

关键词： Asymptotic tracking control barrier Lyapunov functions full state constraints nonlinear pure-feedback systems

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