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Comparative evaluation of data mining methods in predicting the water vapor permeability of cement-based materials

Building Simulation 2023年第6期16卷 853-867页

作者： Xianqi Huang Ruijin Ma Hanyu yang chi Feng Kun Li School of Architecture and Urban Planning Chongqing UniversityChongqing400045China Key Laboratory of New Technology for Construction of Cities in Mountain Area Ministry of EducationChongqing UniversityChongqing400045China Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing400044China College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing400044China

Water vapor permeability of building materials is a crucial parameter for analysing and optimizing the hygrothermal performance of building envelopes and built *** measurement is accurate but time-consuming,while data mining methods have the potential to predict water vapor permeability *** this study,six data mining methods—support vector regression(SVR),decision tree regression(DT),random forest regression(RF),K-nearest neighbor(KNN),multi-layer perceptron(MLP),and adaptive boosting regression(AdaBoost)—were compared to predict the water vapor permeability of cement-based materials.A total of 143 datasets of material properties were collected to build prediction models,and five materials were experimentally determined for model *** results show that RF has excellent generalization,stability,and *** has great generalization and precision,only slightly inferior to the former,and its stability is *** has good precision and acceptable generalization,but its stability is *** and KNN have superior stability,but their generalization and precision are *** lacks generalization,and its stability and precision are *** short,RF has the best comprehensive performance,demonstrated by a limited prediction deviation of 26.3%from the experimental results,better than AdaBoost(38.0%)and DT(38.3%)and far better than other remaining *** is also found that data mining methods provide better predictions when cement-based materials’water vapor permeability is high.

关键词： data mining method cement-based material water vapor permeability cross-validation experimental determination

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Particle segregation mechanism of S–D system in a rotating drum

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Particuology 2024年第10期93卷 300-308页

作者： Erliang Xiao Wei Zhang Zhipeng chi Ran Li Hui yang School of Optical-Electricaland Computer Engineering University of Shanghai for Science and Technology Shanghai 200093China Collegeof Medical Instrumentation Shanghai University of Medicine&Health SciencesShanghaiChina

Complex segregation occurs in a binary particle system with differing particle sizes and densities,particularly when the larger particles are heavier(S–D system,i.e.,size minus density system).Predicting the segregation pattern driven by multiple mechanisms simultaneously is often *** study explores the segregation mechanisms in a quasi-2D circular drum containing a S–D system,realizing a transition between the S-core and Core-and-band patterns by adjusting the drum rotation *** the transition of the segregation pattern,only the S-core pattern chiefly driven by the percolation mechanism is initially *** the rotation speed increases,the buoyancy mechanism and particle diffusion gradually strengthen,jointly driving the formation of the Core-and-band pattern.A dimensionless strength ratio,λ=H/h,where H and h respectively represent the diffusion and buoyancy strengths at length scales,is introduced to elucidate this *** Core-and-band pattern emerges whenλreached 1.4.

关键词： Particle segregation S-Dsystem Segregationmechanisms competition Segregation pattern Rotating drum

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A stable one-point quadrature rule for three-dimensional numerical manifold method

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Science china(Technological Sciences) 2024年第5期67卷 1401-1416页

作者： ZHANG Ning ZHENG Hong yang Liang WU WenAn YUAN chi School of Civil Engineering Qinghai UniversityQinghai810016China Key Laboratory of Urban Security and Disaster Engineering Ministry of EducationBeijing University of TechnologyBeijing100124China Faculty of Engineering China University of GeoscienceWuhan430074China

We present a numerically stable one-point quadrature rule for the stiffness matrix and mass matrix of the three-dimensional numerical manifold method(3D NMM).The rule simplifies the integration over irregularly shaped manifold elements and overcomes locking issues,and it does not cause spurious modes in modal *** essential idea is to transfer the integral over a manifold element to a few moments to the element center,thereby deriving a one-point integration rule by the moments and making modifications to avoid locking *** the stiffness matrix,after the virtual work is decomposed into moments,higher-order moments are modified to overcome locking issues in nearly incompressible and bending-dominated *** the mass matrix,the consistent and lumped types are derived by *** particular,the lumped type has the clear advantage of *** proposed method is naturally suitable for 3D NMM meshes automatically generated from a regular *** tests justify the accuracy improvements and the stability of the proposed procedure.

关键词： three-dimensional numerical manifold method quadrature rule locking mass lumping

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Enhancing the Hydrogen Embrittlement Resistance of Medium Mn Steels by Designing Metastable Austenite with a Compositional Core-shell Structure

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1059-1077页

作者： Jun Zhang Binhan Sun Zhigang yang chi Zhang Hao Chen Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Key Laboratory of Pressure Systems and Safety Ministryof EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China

Deformation-induced martensite transformation from metastable retained austenite is one of the most efficient strain-hardening mechanisms contributing to the enhancement of strength-ductility synergy in advanced high-strength ***,the hard transformation product(often-martensite)and the H redistribution associated with phase transformation essentially decrease materials’resistance to hydrogen *** solve this fundamental conflict,we introduce a new microstructure architecting strategy based on an accurately design of core–shell compositional distribution inside the austenite *** employed this approach in a typical medium Mn steel(8 wt.%Mn)with an ultrafine grained austenite-ferrite *** produced a high Mn content(15–16 wt.%)in the austenite shell region and a low Mn content(~12 wt.%)in the core region,through a thermodynamics-guided two-step austenite reversion *** room-temperature deformation,the austenite core transforms continuously starting from a low strain,providing a high and persistent strain-hardening *** transformation of Mn-rich austenite shell,on the other hand,occurs only at the latest regime of the deformation,thus effectively inhibiting the nucleation of H-induced cracks at ferrite/deformation-induced martensite interfaces as well as suppressing their growth and *** step-wise transformation,tailored directly targeted to protect the hydrogen-sensitive microstructure defects(interfaces),results in a significantly enhanced hydrogen embrittlement resistance without sacrificing the mechanical performance in hydrogen-free *** design of compositional core–shell structure is expected to be applicable to,at least,other multiphase advanced high-strength steels containing metastable austenite.

关键词： Medium Mn steels Hydrogen embrittlement Core-shell austenite Chemical heterogeneity Deformationinduced martensite transformation

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Experimental and theoretical analysis of equilibrium segregation and radiation-induced segregation of Cr at grain boundariesin a reduced activation ferritic/martensitic(RAFM)steel

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Journal of Iron and Steel Research International 2021年第4期28卷 445-452页

作者： Li-dong Xia Hao Chen Zhi-gang yang chi Zhang Key Laboratory of Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

Helium ion irradiation at 350℃was performed to study equilibrium segregation and radiation-induced segregation(RIS)of Cr at grain boundaries in reduced activation ferritic/martensitic *** concentration at grain boundary was measured by scanning transmission electron microscopy with an energy-dispersive *** measured Cr concentration at grain boundaries in heat treated zone was 11.7 and 12.8 wt.%in irradiated zone,respectively,which matched well to the calculated results from Mclean and modified Perk *** segregation and RIS of Cr mechanisms were theoretically *** analysis indicates that as temperature rises,equilibrium Cr segregation decreases monotoni-cally,while RIS of Cr has a bell-shape profile,which increases first and then *** is also shown that at low and high temperatures,equilibrium segregation of Cr is higher than that of RIS;at intermediate temperatures,equilibrium Cr segregation is lower than RIS.

关键词： Reduced activation ferritic/martensitic steel Equilibrium Cr segregation Radiation-induced segregation Grain boundary Rate theory Mclean equation

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Pd-La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)composite as active and stable oxygen electrode for reversible solid oxide cells

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Journal of Rare Earths 2023年第4期41卷 599-604页

作者： Rui yang Yunfeng Tian Yun Liu Jian Pu Bo chi Center for Fuel Cell Innovation State Key Laboratory of Material Processing and Die&Mould TechnologyHuazhong University of Science and TechnologyWuhan 430074China Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization School of Materials Science and PhysicsChina University of Mining and TechnologyXuzhou 221116China

To promote the electrocatalytic activity and stability of traditional(a_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ)(LSCF)oxygen electrodes in reversible solid oxide cells(RSOCs),conventional physical mixed method was used to prepare the Pd-LSCF composite oxygen *** cell with Pd-LSCF|GDC|YSZ|Ni-YSZ configuration shows perfect electrochemical performance in both solid oxide fuel cell(SOFC)mode and solid oxide electrolysis cell(SOEC)*** the SOFC mode,the cell achieves a power density of 1.73 W/cm^(2)at800℃higher than that of the LSCF oxygen electrode with 1.38 W/cm^(2).In the SOEC mode,the current density at 1.5 V is 1.67 A/cm^(2)at 800℃under 50 vol%steam ***,the reversibility and stability of the RSOCs were tested during 192 h long-term reversible *** degradation rate of the cell is only 2.2%/100 h and 2.5%/100 h in the SOEC and the SOFC modes,*** results confirm that compositing Pd with the LSCF oxygen electrode can considerably boost the electrochemical performance of LSCF electrode in RSOCs field.

关键词： Reversible solid oxide cells Composite Oxygen electrode La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) Electrochemical performance Rare earths

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Discussion on blasting vibration monitoring for rock damage control in rock slope excavation

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Earthquake Engineering and Engineering Vibration 2022年第1期21卷 53-65页

作者： yang Jianhua Cai Jiyong Yao chi Zhang Xiaobo Liu Liansheng School of Civil Engineering and Architecture Nanchang UniversityNanchang 30031China School of Resource and Environmental Engineering Jiangxi University of Science and TechnologyGanzhou 341000China

Drill and blast is a commonly used method for rock slope excavation in hydropower *** blasting excavation of rock slopes,far-field vibration monitoring on the first upper berm for statutory compliance is usually performed to control the blast-induced rock damage to the final slope *** this study,for the rock slope excavation in the Jinping-I hydropower station,the field vibration monitoring and acoustic testing are presented to investigate the vibration characteristics on the first upper berm and the damage depth in the current *** relationship between the PPV on the first upper berm and the PPV damage threshold on the damage zone boundary is also studied through three-dimensional FEM *** results show that on the first upper berm,the maximum vibration velocity component occurs in the vertical *** on the blasting damage zone boundary,the horizontal radial vibration velocity is the maximum *** the Jinping-I slope with a bench height of 30 m,the radial PPV on the inner side of the first upper berm is 2.06%of the PPV threshold on the damage zone *** ratio is increased as the bench height ***,the bench height of the rock slope is an important factor that cannot be ignored in determining the allowable vibration velocity for rock damage control.

关键词： rock slope blasting excavation vibration rock damage

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Clinical significance of exosomes as potential biomarkers in cancer

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World Journal of Clinical Cases 2019年第2期7卷 171-190页

作者： chi-Hin Wong yang-Chao Chen School of Biomedical Sciences Faculty of Medicine The Chinese University of Hong Kong Shenzhen Research Institute The Chinese University of Hong Kong

BACKGROUND Exosomes are microvesicles, measuring 30-100 nm in diameter. They are widely distributed in body fluids, including blood, bile, urine and saliva. Cancer-derived exosomes carry a wide variety of DNA, RNA, proteins and lipids, and may serve as novel biomarkers in *** To summarize the performance of exosomal biomarkers in cancer diagnosis and *** Relevant publications in the literature were identified by search of the "PubMed"database up to September 11, 2018. The quality of the included studies was assessed by QUADAS-2 and REMARK. For assessment of diagnostic biomarkers,47 biomarkers and 2240 patients from 30 studies were *** Our results suggested that these exosomal biomarkers had excellent diagnostic ability in various types of cancer, with good sensitivity and specificity. For assessment of prognostic markers, 50 biomarkers and 4797 patients from 42 studies were included. We observed that exosomal biomarkers had prognostic values in overall survival, disease-free survival and recurrence-free *** Exosomes can function as potential biomarkers in cancer diagnosis and prognosis.

关键词： Exosome Biomarker Cancer Diagnosis Prognosis

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Analysis of flow-sediment rating curve hysteresis based on flow and sediment travel time estimations

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International Journal of Sediment Research 2018年第2期33卷 171-182页

作者： chi-Cheng yang Kwan Tun Lee Water Resources Agency Department of River & Harbor Engineering National Taiwan Ocean University

A flow-sediment rating curve is used to describe the relation between flow discharge and suspendedsediment concentration for a specific location. Five types of flow-sediment rating curves-single-valued line, clockwise loop, counterclockwise loop, single-valued line plus loop, and figure eight-were found to rely on the flow and available sediment arriving at the measuring site. In this study, equations for flow and sediment travel time were derived according to soil, rainfall, and watershed geomorphologic characteristics. The hysteresis of the rating curve was related to the travel times by a series of numerical *** data collected from the Goodwin Creek Experimental Watershed, Mississippi, United States were used to verify the proposed rating curve hysteresis analysis. The results indicate that when the flow travel time is more extended than the sediment travel time, the rating curve shows a clockwise loop. A counterclockwise loop in the rating curve shows that the flow travel time is less extended than the sediment travel time. If the flow travel time exceeds the sediment travel time in specific runoff states and is less than the sediment travel time in other runoff states, then a single line plus a loop rating curve or a figure-eight rating curve is observed. The criterion for the model parameters to obtain equalization of the flow and sediment travel times was derived, which can identify the type of flow-sediment rating curve in a specific watershed.

关键词： Flow-sediment rating curve Flow travel time Sediment travel time Instantaneous unit sedimentgraph Kinematic wave Geomorphologic IUH

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Design and modulation principles of molybdenum carbide-based materials for green hydrogen evolution

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Journal of Energy Chemistry 2020年第9期29卷 398-423,I0012页

作者： Jing-Qi chi Min yang Yong-Ming Chai Zhi yang Lei Wang Bin Dong State Key Laboratory of Heavy Oil Processing College of ScienceChina University of Petroleum(East China)Qingdao 266580ShandongChina Key Laboratory of Thin Film and Microfabrication(Ministry of Education) Department of Micro/Nano ElectronicsSchool of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shandong Key Laboratory of Biochemical Analysis College of Chemistry and Molecular EngineeringQingdao University of Science and TechnologyQingdao 266042ShandongChina

The green production of hydrogen from electrocatalytic water splitting is an important base and promising direction for the future of the large-scale application of hydrogen *** key of green hydrogen evolution depends on the development of low-cost and highly active *** carbides(MoxC),as a typical of earth-abundant transition-metal material,have accumulated great attention due to their low cost,earth abundance,electrical conductivity,similar d-band state to Pt,and regulated morphology/electronic *** this paper,recent researches focusing on MoxC for efficient HER in a wide pH range are summarized from respects of modulation of unique morphology,electronic structure,and electrode interface step by ***,modulation of morphology influence the apparent activity of catalyst,modulation of electronic structure of active sites by heteroatom doping and designing heterointerface boost intrinsic HER kinetics,and modulation of electrode interface via hybridization of MoxC structures with carbon materials can ensure the fast electron transfer and boost the *** the above methods discussed,perspective and challenges of designing MoxC as the substitute of Pt-based electrocatalyst for practical hydrogen generation in a wide pH range are pointed out.

关键词： Molybdenum carbides Classification Electrocatalyst Modulation strategy Hydrogen evolution

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