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Frontiers of Structural and Civil engineering 2024年第1期18卷 66-79页

作者： Yaxin TAO Xiaodi DAI Geert de SCHUTTER Kim Van TITTELBOOM department of Structural engineering and building Materials Ghent UniversityGhent 9052Belgium

Robotic-based technologies such as automated spraying or extrusion-based 3-dimensional(3D)concrete printing can be used to build tunnel linings,aiming at reducing labor and mitigating the associated safety issues,especially in the high-geothermal environment.Extrusion-based 3D concrete printing(3DCP)has additional advantages over automated sprayings,such as improved surface quality and no rebound.However,the effect of different temperatures on the adhesion performance of 3D-printed materials for tunnel linings has not been investigated.This study developed several alkali-activated slag mixtures with different activator modulus ratios to avoid the excessive use of Portland cement and enhance sustainability of 3D printable materials.The thermal responses of the mixtures at different temperatures of 20 and 40℃ were studied.The adhesion strength of the alkali-activated material was evaluated for both early and later ages.Furthermore,the structural evolution of the material exposed to different temperatures was measured.This was followed by microstructure characterization.Results indicate that elevated temperatures accelerate material reactions,resulting in improved early-age adhesion performance.Moreover,higher temperatures contribute to the development of a denser microstructure and enhanced mechanical strength in the hardened stage,particularly in mixtures with higher silicate content.

关键词： alkali-activated material 3DCP tunnel lining high-geothermal environment adhesion

Assessing the energy saving potential of using adaptive setpoint temperatures:The case study of a regional adaptive comfort model for Brazil in both the present and the future

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building Simulation 2024年第3期17卷 459-482页

作者： Daniel Sánchez-García David Bienvenido-Huertas Carlos Rubio-Bellido Ricardo Forgiarini Rupp department of Electrical engineering University Carlos III of MadridMadridSpain department of building Simulation ZEROCEM SLSevilleSpain department of building Constructions University of GranadaGranadaSpain department of building Constructions II University of SevilleSevilleSpain Section of Design for Sustainability Department of Civil and Mechanical EngineeringTechnical University of DenmarkKgs.LyngbyDenmark

It has been found in recent years that using setpoint temperatures based on adaptive thermal comfort models is a successful method of energy conservation.Recent studies using adaptive setpoint temperatures incorporate international models from ASHRAE Standard 55 and EN16798-1.This study,however,has instead considered a regional Brazilian adaptive comfort model.This study investigates the energy demand arising from the use of a local Brazilian comfort model in order to assess the energy implications from the use of the worldwide ASHRAE Standard 55 adaptive model and various fixed setpoint temperatures.All of Brazil’s climate zones,full air-conditioning,mixed-mode building operating modes,present-day climate change scenarios,and future scenarios—specifically Representative Concentration Pathways(RCP)2.6,4.5,and 8.5 for the years 2050 and 2100—have all been taken into account in building energy simulations.The use of adaptive setpoint temperatures based on the Brazilian local model considering mixed-mode has been found to significantly reduce energy consumption when compared to static setpoint temperatures(average energy-saving values ranging from 52%to 58%)and the ASHRAE 55 adaptive model(average values ranging from 15%to 21%).Considering climate change and the mixed-mode Brazilian model,the overall energy demand for the three groups of climatic zones(annual average outdoor temperatures≤21℃,>21 and≤25℃and>25℃)ranged between 2%decrease and 5%increase,4%and 27%increase,and 13%and 45%increase,respectively.It is concluded as a consequence that setting setpoint temperatures based on the Brazilian local adaptive comfort model is a very efficient energy-saving method.

关键词： adaptive thermal comfort building energy simulation energy efficiency climate change adaptive setpoint temperatures local comfort mode

A reinforcement learning approach for thermostat setpoint preference learning

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building Simulation 2024年第1期17卷 131-146页

作者： Hussein Elehwany Mohamed Ouf Burak Gunay Nunzio Cotrufo Jean-Simon Venne department of Environmental engineering Carleton UniversityOttawaCanada departmentof building Civiland Environmental EngineeringConcordia UniversityMontrealCanada BrainBox Al Inc. MontrealCanada

Occupant-centric controls(OcC)is an indoor climate control approach whereby occupant feedback is used in the sequence of operation of building energy systems.While OcC has been used in a wide range of building applications,an OcC category that has received considerable research interest is learning occupants'thermal preferences through their thermostat interactions and adapting temperature setpoints accordingly.Many recent studies used reinforcement learning(RL)as an agent for OcC to optimize energy use and occupant comfort.These studies depended on predicted mean vote(PMV)models or constant comfort ranges to represent comfort,while only few of them used thermostat interactions.This paper addresses this gap by introducing a new off-policy reinforcement learning(RL)algorithm that imitates the occupant behaviour by utilizing unsolicited occupant thermostat overrides.The algorithm is tested with a number of synthetically generated occupant behaviour models implemented via the Python APl of EnergyPlus.The simulation results indicate that the RL algorithm could rapidly learn preferences for all tested occupant behaviour scenarios with minimal exploration events.While substantial energy savings were observed with most occupant scenarios,the impact on the energy savings varied depending on occupants'preferences and thermostat use behaviour stochasticity.

关键词： reinforcement learning preference learning occupant-centric controls smart thermostats off-policy learning

Tensile strength and failure behavior of rock-mortar interfaces: Direct and indirect measurements

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Journal of Rock Mechanics and Geotechnical engineering 2024年第1期16卷 41-55页

作者： Ghasem Shams Patrice Rivard Omid Moradian Civil engineering and building engineering department Universitéde SherbrookeSherbrookeQuébecCanada department of Earth Sciences Swiss Federal Institute of Technology(ETH)ZurichSwitzerland department of Civil and Environmental engineering Colorado School of MinesGoldenCOUSA

The tensile strength at the rock-concrete interface is one of the crucial factors controlling the failure mechanisms of structures,such as concrete gravity dams.Despite the critical importance of the failure mechanism and tensile strength of rock-concrete interfaces,understanding of these factors remains very limited.This study investigated the tensile strength and fracturing processes at rock-mortar interfaces subjected to direct and indirect tensile loadings.Digital image correlation(DIC)and acoustic emission(AE)techniques were used to monitor the failure mechanisms of specimens subjected to direct tension and indirect loading(Brazilian tests).The results indicated that the direct tensile strength of the rock-mortar specimens was lower than their indirect tensile strength,with a direct/indirect tensile strength ratio of 65%.DIC strain field data and moment tensor inversions(MTI)of AE events indicated that a significant number of shear microcracks occurred in the specimens subjected to the Brazilian test.The presence of these shear microcracks,which require more energy to break,resulted in a higher tensile strength during the Brazilian tests.In contrast,microcracks were predominantly tensile in specimens subjected to direct tension,leading to a lower tensile strength.Spatiotemporal monitoring of the cracking processes in the rock-mortar interfaces revealed that they show AE precursors before failure under the Brazilian test,whereas they show a minimal number of AE events before failure under direct tension.Due to different microcracking mechanisms,specimens tested under Brazilian tests showed lower roughness with flatter fracture surfaces than those tested under direct tension with jagged and rough fracture surfaces.The results of this study shed light on better understanding the micromechanics of damage in the rock-concrete interfaces for a safer design of engineering structures.

关键词： Rock-mortar Rock-concrete Moment tensor inversion(MTI) Acoustic emission(AE) Digital image correlation(DIC) Tensile strength Direct tensile test Brazilian test

Performance assessment of prefabricated vertical drains in mitigating soil reliquefaction subjected to repeated seismic events using shaking table experiments

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Frontiers of Structural and Civil engineering 2024年第3期18卷 411-427页

作者： Gowtham PADMANABHAN Ganesh Kumar SHANMUGAM department of Earthquake engineering Indian Institute of Technology RoorkeeUttarakhand 247667India Geotechnical engineering Division CSIR-Central building Research Institute Academy of Scientific and Innovative Research(AcSIR)Uttarakhand 247667India

The use of prefabricated vertical drains(PVD)in liquefiable deposits is gaining attention due to enhanced drainage.However,investigations on PVD in mitigating re-liquefaction during repeated shaking events are not available.This study performed a series of shaking table experiments on untreated and PVD-treated specimens prepared with 40%and 60%relative density.Repeated sinusoidal loading was applied with an incremental peak acceleration of 0.1g,0.2g,0.3g,and 0.4g,at 5 Hz shaking frequency with 40 s duration.The performance of treated ground was evaluated based on the generation and dissipation of excess pore water pressure(EPWP),induced sand densification,subsidence,and cyclic stress ratio.In addition,the strain accumulated in fresh and exhumed PVD was investigated using geotextile tensile testing apparatus aided with digital image correlation.No evidence of pore pressure was reported up to 0.2g peak acceleration for 40%and 60%relative density specimens.The continuous occurrence of soil densification and drainage medium restrained and delayed the generation of EPWP and expedited the dissipation process.This study demonstrates PVD can mitigate re-liquefaction,without suffering from deterioration,when subjected to medium to high intense repeated shaking events.

关键词： prefabricated vertical drains drainage re-liquefaction shaking table digital image correlation

Impact of a Magnetic Dipole on Heat Transfer in Non-Conducting Magnetic Fluid Flow over a Stretching Cylinder

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Fluid Dynamics & Materials Processing 2024年第3期20卷 475-486页

作者： Anupam Bhandari department of Mathematics School of EngineeringUniversity of Petroleum&Energy Studies(UPES)Energy Acres BuildingBidholi DehradunUttarakhand248007India

The thermal behavior of an electrically non-conducting magnetic liquid flowing over a stretching cylinder under the influence of a magnetic dipole is considered.The governing nonlinear differential equations are solved numerically using a finite element approach,which is properly validated through comparison with earlier results available in the literature.The results for the velocity and temperature fields are provided for different values of the Reynolds number,ferromagnetic response number,Prandtl number,and viscous dissipation parameter.The influence of some physical parameters on skin friction and heat transfer on the walls of the cylinder is also investigated.The applicability of this research to heat control in electronic devices is discussed to a certain extent.

关键词： Ferrofluid stretching cylinder finite element method heat transfer magnetic dipole

Hydroxyl radical production by abiotic oxidation of pyrite under estuarine conditions:The effects of aging,seawater anions and illumination

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Journal of Environmental Sciences 2024年第1期135卷 715-727页

作者： Ruixue Liu Yinshun Dai Yucheng Feng Shiwen Sun Xiaodong Zhang Chunjiang An Shan Zhao Shandong Key Laboratory of Water Pollution Control and Resource Reuse School of Environmental Science and EngineeringShandong UniversityQingdao 266237China department of building Civil and Environmental EngineeringConcordia UniversityMontrealQC H3G 1M8Canada

Pyrite is widely distributed in estuarine sediments as an inexpensive natural Fenton-like reagent,however,the mechanism on the hydroxyl radical(HO^(·))production by pyrite under estuarine environmental conditions is still poorly understood.The batch experiments were performed to investigate the effects of estuarine conditions including aging(in air,in water),seawater anions(Cl^(-),Br^(-)and HCO_(3)^(-))and light on the HO^(·)production by pyrite oxidation.The one-electron transfer dominated the process from O_(2) to HO^(·)induced by oxidation of pyrite.The Fe(oxyhydr)oxide coatings on the surface of pyrite aged in air and water consumed hydrogen peroxide while mediating the electron transfer,and the combined effect of the two resulted in a suppression of HO^(·)production in the early stage of aging and a promotion of HO^(·)production in the later stage of aging.Corrosion of the surface oxide layers by aggressive anions was the main reason for the inhibition of HO^(·)production by Cl^(-)and Br^(-),and the generation of Cl^(·)and Br^(·)may also play a role in the scavenging of HO^(·).HCO_(3)^(-)increased the average rate of HO^(·)production through surface-CO_(2) complexes formed by adsorption on the surface of pyrite.The significant enhancement of HO^(·)production under light was attributed to the formation of photoelectrons induced by photochemical reactions on pyrite and its surface oxide layers.These findings provide new insights into the environmental chemical behavior of pyrite in the estuary and enrich the understanding of natural remediation of estuarine environments.

关键词： Hydroxyl radical Pyrite oxidation Aging Anions Irradiation

An integrated computational method for calculating dynamic thermal bridges of building facades in tropical countries

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Frontiers of Architectural Research 2024年第1期13卷 201-218页

作者： Miktha Farid Alkadri Muhammad Rafif Cahyadi Agung Francesco De Luca Research Cluster of Architectural Sciences and building Technology Department of ArchitectureFaculty of EngineeringUniversitas IndonesiaDepok 16425Indonesia department of Civil engineering and Architecture Tallinn University of TechnologyTallinn 19086Estonia

Identifying thermal bridges on building façades has been a great challenge for architects,especially during the conceptual design stage.This is not only due to the complexity of parameters when calculating thermal bridges,but also lack of feature integration between building energy simulation(BES)tools and the actual building conditions.For example,existing BES tools predominantly calculate thermal bridges only in steady state without considering the temperature dynamic behaviour of building outdoors.Consequently,relevant features such as thermal delay,decrement factor,and operative temperature are often neglected,and this can lead to miscalculation of energy consumption.This study then proposes an integrated method to calculate dynamic thermal bridges under transient conditions by incorporating field observations and computational simulations of thermal bridges.More specifically,the proposed method employs several measurement tools such as HOBO data logger to record the actual conditions of indoor and outdoor room temperature and thermal cameras to identify the surface temperature of selected building junctions.The actual datasets are then integrated with the simulation workflow developed in BES tools.This study ultimately enables architects not only to identify potential thermal bridges on existing building façades but also to support material and geometric exploration in early design phase.

关键词： Thermal bridges Dynamic calculation Thermal delay Cooling load Computational design method

Synergistic effect of adsorption and photocatalytic degradation of oilfield-produced water by electrospun photocatalytic fibers of Polystyrene/Nanorod-Graphitic carbon nitride

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Journal of Environmental Sciences 2024年第7期141卷 287-303页

作者： Parisa Azmoon Mehrdad Farhadian Alireza Pendashteh Amir H.Navarchian department of Chemical engineering Faculty of EngineeringUniversity of IsfahanIsfahanIran department of Chemical engineering Faculty of EngineeringUniversity of GuilanRashtIran department of Water and Environmental engineering Caspian Sea Basin Research CenterUniversity of GuilanRashtIran

Graphitic carbon nitride with nanorod structure(Nr-GCN)was synthesized using melamine as a precursor without any other reagents by hydrothermal pretreatment method.XRD,FTIR,SEM,N_(2)adsorption-desorption from BET,UV-Vis DRS spectroscopy,and photoluminescence were used to characterize the prepared samples.Also,the photoelectrochemical behavior of nanoparticles was studied by photocurrent transient response and cyclic voltammetry analysis.Polystyrene(PS)fibrous mat was fabricated by electrospinning technique and used as a support for the stabilization of the nanoparticles.The performance of the synthesized nanoparticles and photocatalytic fibers(PS/Nr-GCN)was evaluated in oilfield-produced water treatment under visible light irradiation.During this process,oil contaminants were adsorbed by hydrophobic polystyrene fibers and simultaneously degraded by Nr-GCN.The removal efficiency of chemical oxygen demand(COD)has been obtained 96.6%and 98.4%by Nr-GCN and PS/Nr-GCN,respectively,at the optimum conditions of pH4,photocatalyst dosage 0.5 g/L,COD initial concentration 550 mg/L,and illumination time 150 min.The gas chromatography-mass spectroscopy analysis results showed 99.3%removal of total petroleum hydrocarbons using photocatalytic fibers of PS/Nr-GCN.The results demonstrated that the GCN has outstanding features like controllable morphology,visible-light-driven,and showing high potential in oily wastewater remediation.Moreover,the synergistic effect of adsorption and photocatalytic degradation is an effective technique in oilfield-produced water treatment.

关键词： Graphitic carbon nitride(GCN) Nanorod structure Polystyrene fibrous mat Photocatalytic fibers Oilfield-produced water(OPW)

Effect of linear friction welding process on microstructure evolution,mechanical properties and corrosion behavior of GH4169 superalloy

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Chinese Journal of Aeronautics 2024年第6期37卷 504-520页

作者： Yu SU Xiawei YANG Tingxi MENG Dong WU Rui XU Haiyu XU Wenya LI Shuo YIN State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China department of Mechanical Manufacturing&Biomedical EngineeringParsons BuildingTrinity College DublinThe University of DublinDublin 2Ireland

Linear Friction Welding(LFW)technology was used to realize the welding of GH4169 superalloy,and the effect of welding parameters on the microstructure,mechanical properties and corrosion behavior of the joint was analyzed.The results show that there is a positive correlation between the weld hardness and the tensile strength.With the gradual increase of heat input and welding pressure,the joint quality is gradually improved,but the heat affected zone is not significantly increased.The smaller the grain size of the weld,the higher the strength and plasticity of the joint.With the increase of the joint shortening amount,the corrosion resistance of the weld first gradually increases.However,when the shortening reaches a certain level,the corrosion resistance of the joint becomes little changed.With the increase of solution temperature,the corrosion current density increases and the polarization impedance decreases.The higher the corrosion temperature,the worse the corrosion resistance of the joint.There is no significant correlation between the joint strength and the corrosion resistance.The corrosion resistance of the joint can be enhanced without changing the joint mechanical properties by reducing the welding frequency and amplitude or increasing the welding pressure.

关键词： Linear FrictionWelding(LFW) GH4169 superalloy Microstructure Mechanical properties Corrosion behavior