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Numerical study of axial-loaded circular concrete-filled aluminum tubular slender columns

Frontiers of Structural and Civil Engineering 2024年第2期18卷 272-293页

作者： Xudong CHEN Jeung-Hwan DOH Sanam AGHDAMY School of Engineering and built environment Griffith University Gold Coast CampusBrisbaneQLD 4222Australia

Aluminum alloys have been widely applied in coastal and marine structures because of their superior sustainability and corrosion resistance.Concrete-filled double-skin aluminum tubular columns(CFDAT)possess higher strength and better ductility than traditional reinforced concrete structures.However,few studies have been conducted on numerical simulation methods for circular CFDATs.Specifically,there has been no experimental or numerical study on intermediate-to-slender circular CFDATs.Here,a comprehensive numerical study was conducted on a modeling method for the first time to simulate the axial behavior of a slender circular CFDAT.This study outlines the development of numerical modeling techniques and presents a series of comparative studies using various material nonlinearities,confinement effects,and nonlinearity of the initial geometric imperfections for a slender column.The numerical results were compared with more than 80 previously available stub and slender experimental test results for verification.It was confirmed that the proposed numerical technique was reliable and accurate for simulating the axial behavior of intermediate and slender circular CFDAT.Furthermore,a parametric study was conducted to investigate the effects of geometric and material properties on the axial capacity of the CFDAT.Additionally,the slenderness and strength-to-width ratio of CFDAT were compared with those of concrete-filled double-skin steel tubular columns(CFDST).The simulated axial strengths were compared with those predicted using AS 5100 and AISC 360.New design equations for the CFDATs should be proposed based on AS 5100.

关键词： axial behavior aluminum concrete-filled double-skin slender columns numerical modelling

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A comparison of model choice strategies for logistic regression

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Journal of Data and Information Science 2024年第1期9卷 37-52页

作者： Markku Karhunen built environment Solutions unit Finnish Environment Institute(Syke)Latokartanonkaari 1100790 HelsinkiFinland

Purpose:The purpose of this study is to develop and compare model choice strategies in context of logistic regression.Model choice means the choice of the covariates to be included in the model.Design/methodology/approach:The study is based on Monte Carlo simulations.The methods are compared in terms of three measures of accuracy:specificity and two kinds of sensitivity.A loss function combining sensitivity and specificity is introduced and used for a final comparison.Findings:The choice of method depends on how much the users emphasize sensitivity against specificity.It also depends on the sample size.For a typical logistic regression setting with a moderate sample size and a small to moderate effect size,either BIC,BICc or Lasso seems to be optimal.Research limitations:Numerical simulations cannot cover the whole range of data-generating processes occurring with real-world data.Thus,more simulations are needed.Practical implications:Researchers can refer to these results if they believe that their data-generating process is somewhat similar to some of the scenarios presented in this paper.Alternatively,they could run their own simulations and calculate the loss function.Originality/value:This is a systematic comparison of model choice algorithms and heuristics in context of logistic regression.The distinction between two types of sensitivity and a comparison based on a loss function are methodological novelties.

关键词： Model choice Logistic regression Logit regression Monte Carlo simulations Sensitivity Specificity

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Optimising multi-vent module-based adaptive ventilation using a novel parameter for improved indoor air quality and health protection

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Building Simulation 2024年第1期17卷 113-130页

作者： Haotian Zhang Xiaoxiao Ding Weirong Zhang Weijia Zhang Yingli Xuan Key Laboratory of Green built environment and Energy Efficient Technology Beijing University of TechnologyBeijing 100124China Department ofArchitecture TokyoPolytechnic UniversityTokyoJapan

As infectious respiratory diseases are highly transmissible through the air,researchers have improved traditional total volume air distribution systems to reduce infection risk.Multi-vent module-based adaptive ventilation(MAV)is a novel ventilation type that facilitates the switching of inlets and outlets to suit different indoor scenarios without changing ductwork layout.However,little research has evaluated MAV module sizing and air velocity selection,both related to MAV system efficiency in removing contaminants and the corresponding level of protection for occupants in the ventilated room.Therefore,the module-source offset ratio(MSOR)is proposed,based on the MAV module size and its distance from an infected occupant,to inform selection of optimal MAV module parameters.Computational fluid dynamics simulations illustrated contaminant distribution in a two-person MAV equipped office.Discrete phase particles modelled respiratory contaminants from the infected occupant,and contaminant concentration distributions were compared under four MAV air distribution layouts,three air velocities,and three module sizes considered using the MsOR.Results indicate that lower air velocities favour rising contaminant levels,provided the ventilation rate is met.Optimal contaminant discharge can be achieved when the line of outlets is located directly above the infected occupant.Using this parameter to guide MAV system design,85.7% of contaminants may be rendered harmless to the human body within 120 s using the default air vent layout.A more appropriate supply air velocity and air vent layout increases this value to 91.4%.These results are expected to inform the deployment of MAV systems to reduce airborne infection risk.

关键词： multi-vent module-based adaptive ventilation computational fluid dynamics indoor air quality infection control

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Evaluating different levels of information on the calibration of building energy simulation models

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Building Simulation 2024年第4期17卷 657-676页

作者： Siyu Cheng Zeynep Duygu Tekler Hongyuan Ji Wenxin Li Adrian Chong Department of the built environment College of Design and EngineeringNational University of Singapore4 Architecture DriveSingapore117566Singapore School of Civil Engineering and Architecture Chongqing University of Science and TechnologyChongqing401331China School of Energy and environment Southeast UniversityNanjing210096China

A poorly calibrated model undermines confidence in the effectiveness of building energy simulation, impeding the widespread application of advanced energy conservation measures (ECMs). Striking a balance between information-gathering efforts and achieving sufficient model credibility is crucial but often obscured by ambiguities. To address this gap, we model and calibrate a test bed with different levels of information (LOI). Beginning with an initial model based on building geometry (LOI 1), we progressively introduce additional information, including nameplate information (LOI 2), envelope conductivity (LOI 3), zone infiltration rate (LOI 4), AHU fan power (LOI 5), and HVAC data (LOI 6). The models are evaluated for accuracy, consistency, and the robustness of their predictions. Our results indicate that adding more information for calibration leads to improved data fit. However, this improvement is not uniform across all observed outputs due to identifiability issues. Furthermore, for energy-saving analysis, adding more information can significantly affect the projected energy savings by up to two times. Nevertheless, for ECM ranking, models that did not meet ASHRAE 14 accuracy thresholds can yield correct retrofit decisions. These findings underscore equifinality in modeling complex building systems. Clearly, predictive accuracy is not synonymous with model credibility. Therefore, to balance efforts in information-gathering and model reliability, it is crucial to (1) determine the minimum level of information required for calibration compatible with its intended purpose and (2) calibrate models with information closely linked to all outputs of interest, particularly when simultaneous accuracy for multiple outputs is necessary.

关键词： calibration building energy simulation(BES) energy conservation measure(ECM) level of information field measurements

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The risk factors and threshold level of subchronic inhalation exposure of reclaimed water

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Journal of environmental Sciences 2024年第3期137卷 639-650页

作者： Jiayang Kong Yun Lu Yunru Ren Menghao Chen Gang Liu Liangliang Shi State Key Joint Laboratory of environment Simulation and Pollution Control State Environment Protection Key Laboratory of Microorganism Application and Risk ControlSchool of EnvironmentTsinghua UniversityBeijing 100084China

Inhalation of reclaimed water is known to cause lung infammation,and free endotoxins have been shown to be a major risk factor for acute exposure.Subchronic exposure has also been shown to induce infammatory responses with visible tissue damage.However,subchronic risk factors have yet to be identified,and a threshold for the protection of occupational populations during urban reuse is necessary.In this study,potential risk factors in reclaimed water were examined by subchronic exposure with fractionated reclaimed water,and the health risk threshold was tested with a series of diluted reclaimed water.Accordingly,following a 12-week exposure,macromolecules and microorganisms were found to be two major risk factors in reclaimed water that could cause pulmonary infammation,including increased proportion of polymorphonuclear leukocytes in bronchoalveolar fuid,formation of inducible bronchus-associated lymphoid tissue,and elevation of Immunoglobulin A levels.Moreover,infammation persisted after a 4-week recovery period.The calculated threshold of reclaimed water exposure for mice was 31.8 Endotoxin Unit(EU)/(kg·day)under when exposed to 50%additional relative humidity from reclaimed water at 25℃ for 2 hr/day.Meanwhile,the subchronic threshold estimate for humans under the same exposure conditions was found to be 12.2 EU/(kg·day),corresponding to endotoxin levels of 61.7 EU/mL in reclaimed water.The threshold level of endotoxin was lower than that in most non-potable reclaimed water.The findings of this study suggest that occupational exposure of reclaimed water can serve as a potential risk to workers.

关键词： Reclaimed water Inhalation exposure Risk factor Threshold Infammation Endotoxin

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Comparison of antimony and arsenic behaviour at the river-lake junction in the middle of the Yangtze River Basin

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Journal of environmental Sciences 2024年第2期136卷 189-200页

作者： Huiji Liu Wei Zeng Ziyang Lai Mengchang He Chunye Lin Wei Ouyang Xitao Liu State Key Laboratory of Water environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China Advanced Interdisciplinary Institute of environment and Ecology Beijing Normal UniversityZhuhai 519087China

As typical metalloid toxic elements widely distributed in environmental media,the geochemical behaviour of antimony(Sb)and arsenic(As)affects environmental safety.We selected the surface waters and sediments at the river-lake junction of Dongting Lake as the research objects,analysed the concentration and chemical partitioning of Sb and As,assessed its contamination and ecological risk levels,and discussed its sources and potential influencing factors.The concentrations of dissolved Sb and As in surface waters were low(environmental behaviour of metalloids in specific hydrological conditions,such as river-lake junctions.

关键词： Contamination Ecological risks Antimony(Sb) Arsenic(As) River-lake junction Dongting Lake

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Advancements in materials for hydrogen production:A review of cutting-edge technologies

ChemPhysMater

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ChemPhysMater 2024年第1期3卷 64-73页

作者： Ahmed Alamiery Department of Chemical and Process Engineering Faculty of Engineering and Built EnvironmentUniversity Kebangsaan Malaysia(UKM)Bangi P.O.Box 43000SelangorMalaysia

Hydrogen,a clean and versatile energy carrier,has gained significant attention as a potential solution for addressing the challenges of climate change and energy sustainability.Efficient hydrogen production relies heavily on the development of advanced materials that enable cost-effective and sustainable methods.This review article presents a comprehensive overview of cutting-edge materials used for hydrogen production,covering both traditional and emerging technologies.This article begins by briefly introducing the importance of hydrogen as a clean energy carrier and various methods used for hydrogen production.This emphasizes the critical role of these materials in enabling efficient hydrogen generation.Traditional methods,such as steam methane reforming,coal gasification,biomass gasification,and water electrolysis,are discussed,highlighting the materials used and their advantages and limitations.This review then focuses on emerging technologies that have shown promise for achieving efficient hydrogen production.Photocatalytic water splitting is explored with an emphasis on recent advancements in semiconductor-based photocatalysts and nanostructured materials for enhanced photocatalysis.Solid oxide electrolysis cells(SOEC)are examined,discussing high-temperature electrolysis materials and advancements in electrolytes and electrode materials.Biological hydrogen production and chemical looping are also discussed,highlighting the use of microorganisms,bioengineered systems,metal oxides as oxygen carriers,and catalysts for improved hydrogen generation.Advanced characterization techniques,including X-ray diffraction,spectroscopy,scanning electron microscopy,transmission electron microscopy,X-ray photoelectron spectroscopy,Auger electron spectroscopy,thermogravimetric analysis,and differential scanning calorimetry,have been used to gain insight into the properties and performances of materials.This review concludes by addressing the challenges and prospects in the field of hydrogen production materials.This highlight

关键词： Hydrogen production Cutting-edge technologies in hydrogen generation Sustainable hydrogen Clean energy

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CBE Clima Tool:A free and open-source web application for climate analysis tailored to sustainable building design

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Building Simulation 2024年第3期17卷 493-508页

作者： Giovanni Betti Federico Tartarini Christine Nguyen Stefano Schiavon Center for the built environment University of California BerkeleyBerkeleyUSA Berkeley Education Alliance for Research in Singapore SingaporeSingapore Heat and Health Research Incubator Faculty of Medicine and HealthThe University of SydneyCamperdownAustralia College of Letters and Sciences University of California BerkeleyBerkeleyUSA

Climate-responsive building design holds immense potential for enhancing comfort,energy efficiency,and environmental sustainability.However,many social,cultural,and economic obstacles might prevent the wide adoption of designing climate-adapted buildings.One of these obstacles can be removed by enabling practitioners to easily access,visualize and analyze local climate data.The CBE Clima Tool(Clima)is a free and open-source web application that offers easy access to publicly available weather files and has been created for building energy simulation and design.It provides a series of interactive visualizations of the variables contained in the EnergyPlus Weather Files and several derived ones like the UTCI or the adaptive comfort indices.It is aimed at students,educators,and practitioners in the architecture and engineering fields.Since its inception,Clima’s user base has exhibited robust growth,attracting over 25,000 unique users annually from across 70 countries.Our tool is poised to revolutionize climate-adaptive building design,transcending geographical boundaries and fostering innovation in the architecture and engineering fields.

关键词： architectural design climate analysis sustainable building design web application building energy simulation open-source software

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Uncovering the coupling effect with energy-related carbon emissions and human development variety in Chinese provinces

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Journal of environmental Sciences 2024年第5期139卷 527-542页

作者： Liu Chen Yiqi Tan Gengpei Lv Weiguang Cai Xiaofeng Gao Rui Li School of Management Science and Real Estate Chongqing UniversityChongqing 400044China State Key Joint Laboratory of environment Simulation and Pollution Control(SKLESPC) School of EnvironmentTsinghua UniversityBeijing 100084China Key Laboratory of the Three Gorges Reservoir Region’s Eco-environment Ministry of EducationCollege of Environment and EcologyChongqing UniversityChongqing 400044China

Lessening energy-related carbon emissions has become a crucial measure to achieve Chinese carbon neutrality.This study is the first to construct a Difference in Carbon pressures-adjusted Human Development Index(DCHDI)model for the purpose of exploring the coupling effect between carbon emissions and human development variety from 2000 to 2019 in Chinese provinces.We demonstrate the following.(1)The total energy-related carbon footprint of 30 provinces in China reached 10.2 billion tons in 2019,with an average annual growth rate of 6.93% over the past two decades;and the provinces with the highest carbon emissions per capita are InnerMongolia,Ningxia,and Shanxi.(2)At the provincial level,we observed that the Human Development Index(HDI),which includes life expectancy,education,and income,has been rising,while Beijing,Shanghai,and Tianjin entered the super-high HDI level before 2008.(3)The entire coupling effect of 30 Chinese provinces has been broadly fortified in the last 20 years,but the growth rate of DCHDI values in 2011-2019 has slowed down compared with that in 2000-2010;the clustering phenomenon demonstrated that this discovery is associated with historical peaks in total carbon emissions.(4)The co-ordination degree of carbon emissions per capita and HDI was verified,and 96% of the data points were found in the range of super high coupling coordination degree.Overall,this study provides the government with worthwhile guidance for decision-making and carbon reduction strategies for other countries struggling to advance human sustainable development.

关键词： Energy-related carbon emissions Human sustainable development DCHDI model Coupling effect Chinese provinces

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Time-sensitive prediction of NO_(2) concentration in China using an ensemble machine learning model from multi-source data

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Journal of environmental Sciences 2024年第3期137卷 30-40页

作者： Chenliang Tao Man Jia Guoqiang Wang Yuqiang Zhang Qingzhu Zhang Xianfeng Wang Qiao Wang Wenxing Wang Big Data Research Center for Ecology and environment Environment Research InstituteShandong UniversityQingdao 266237China Shandong Provincial Eco-environment Monitoring Center Jinan 250101China

Nitrogen dioxide(NO_(2))poses a critical potential risk to environmental quality and public health.A reliable machine learning(ML)forecasting framework will be useful to provide valuable information to support government decision-making.Based on the data from1609 air quality monitors across China from 2014-2020,this study designed an ensemble ML model by integrating multiple types of spatial-temporal variables and three sub-models for time-sensitive prediction over a wide range.The ensemble ML model incorporates a residual connection to the gated recurrent unit(GRU)network and adopts the advantage of Transformer,extreme gradient boosting(XGBoost)and GRU with residual connection network,resulting in a 4.1%±1.0%lower root mean square error over XGBoost for the test results.The ensemble model shows great prediction performance,with coefficient of determination of 0.91,0.86,and 0.77 for 1-hr,3-hr,and 24-hr averages for the test results,respectively.In particular,this model has achieved excellent performance with low spatial uncertainty in Central,East,and North China,the major site-dense zones.Through the interpretability analysis based on the Shapley value for different temporal resolutions,we found that the contribution of atmospheric chemical processes is more important for hourly predictions compared with the daily scale predictions,while the impact of meteorological conditions would be ever-prominent for the latter.Compared with existing models for different spatiotemporal scales,the present model can be implemented at any air quality monitoring station across China to facilitate achieving rapid and dependable forecast of NO_(2),which will help developing effective control policies.

关键词： Air quality prediction Deep learning Ensemble method Nitrogen dioxide Spatiotemporal covariates

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