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Upcycling Spent Waterglass Foundry Sand into "Reactive" Fine Aggregates for Alkali-Activated Slag Materials to Achieve Enhanced Compressive Strength

SSRN

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SSRN 2022年

作者： Xie, Jiankai Chen, Peiyuan Hu, Shuimu Xu, Ying Li, Jin Wang, Yonghui School of Civil Engineering and Architecture Anhui University of Science and Technology Huainan232001 China Institute of Environment-friendly Materials and Occupational Health Anhui University of Science and Technology Wuhu241003 China Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong

Spent waterglass foundry sand (SwFS) is a major waste in foundry industry, and should be disposed preferentially. Two SwFSs subjected to 100℃ (SwFS₁) and 800℃ (SwFS₈) were prepared to investigate their effects on the flow, compressive strength, micromechanical properties and pore structure of AASM. Experimental results confirmed that the soluble properties and content of SwFS determined the overall performance of AASM. Both kinds of SwFSs increased the flow values of AASM due to additional silicates. SwFS₁ suffered to 100℃ with high solubilities of the dried waterglass coating released silica tetrahedron into the activation system, contributing to the formation of more and additional hydration products. As a result, the overall performance from the aspects of micro- and macro- mechanical properties, and microstructure of AASM was enhanced. Specially, the compressive strength of SwFS₁-added AASM mortars was increased at all ages, like by 28.9—49.4% at 28d. Whereas, SwFS₈ with low solubilities of waterglass exerted weaker effects on the performance of AASM as compared with SwFS₁. The compressive strength of SwFS₈-added AASM mortars was slightly higher than that of the control mixture, and the maximum increment at 28d was 9.4% in SwFS₈100. In summary, this paper confirmed the feasibility of using SwFS as "reactive" fine aggregates for AASM owing to the the dried waterglass coating . It can be incorporated into AASM in a much safer manner without compromising the mechanical strength. © 2022, The Authors. All rights reserved.

关键词： Compressive strength

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Development of a Simulation Model of an Induction Electric Motor of Vehicles Taking into Account Instantaneous Magnetic Losses in Steel

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SSRN 2024年

作者： Riabov, Ievgen Goolak, Sergey Petrychenko, Olga Kyrychenko, Mykhailo Pohosov, Oleksandr Department of Electromechanics and Rolling Stock of Railways State University of Infrastructure and Technologies Kyrylivska str. 9 Kyiv04071 Ukraine Department of Electrical Transport and Diesel Locomotive National Technical University «Kharkiv Polytechnic Institute» Kyrpychova str. 2 Kharkiv61002 Ukraine Theory and Structure of a Ship Department National University "Odessa Maritime Academy 8 Didrikhson str. Odessa65052 Ukraine Department of Heat Engineering Kyiv National University of Life and Architecture Povitroflotskiy Avenue 31 Kyiv03037 Ukraine

This document describes a mathematical model of an induction electric motor of vehicles taking into account instantaneous magnetic losses in steel. In order to apply the simulation model in conditions of asymmetry of the supply voltage system and the motor windings, the model is made in a three-phase coordinate system using the method of taking into account the influence of the geometric parameters of the windings on the inductance of the motor. Taking into account instantaneous magnetic losses in steel is performed by introducing variable resistances into the electric circuits of the stator and rotor, which are functions of instantaneous magnetic losses in the steel of the electric motor. The simulation results showed a high convergence of the controlled parameters with the results declared by the manufacturer. This approach to the simulation of an induction electric motor will allow the use of the proposed model in the study of electromechanical processes in the traction drive system, taking into account the peculiarities of the operating modes of electric transport. © 2024, The Authors. All rights reserved.

关键词： Winding

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Impact of opening ratio on seismic performance of light-gauge steel structure 3

Impact of opening ratio on seismic performance of light-gaug...

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3rd International Conference on Optoelectronic Science and Materials, ICOSM 2021

作者： Zheng, Xinzhi Zhang, Yuanhong Zheng, Shuang Ecological Architecture and Environment Construction Henan Province Engineering Laboratory Henan Polytechnic University Henan Jiaozuo454000 China Department of Architectural Engineering Tianjin Renai College Tianjin301636 China Guangdong Tianwei Construction Co. LTD Guangdong Guangzhou510310 China School of Civil Engineering Tsinghua University Beijing100004 China Shanyang District Housing and Urban-Rural Development Bureau Henan Jiaozuo454150 China

ISBN: (数字)9781510649323

ISBN: (纸本)9781510649316

The web light-gauge steel system is a new type of steel structure, which has a good application prospect. However, in practical application, the problem of large opening in the wall often leads to a large opening ratio in structure, which has a negative impact on the structural safety. In this paper, according to the characteristics of the light-gauge steel structure, using ABAQUS finite element software and reasonable simplified modeling method, the validity of the model is verified by modal analysis, and the natural vibration period and modal calculation results of the structure are obtained, and the calculation results are consistent with those in the literature. The modal analysis and time history analysis of the structural model with different opening ratios show that: with the increase of opening ratio, the natural vibration period of the structure is approximately 1:1 linear growth, and the displacement growth is slow first and then fast, shows a critical change point. Based on the analysis results, reasonable design suggestions for different seismic fortification intensity regions are put forward. © 2021 SPIE.

关键词： Modal analysis

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Addressing Informal Public Transport Vehicle Problem in Kolkata 3rd

Addressing Informal Public Transport Vehicle Problem in Kolk...

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3rd National Conference on Recent Advances in Traffic engineering, RATE 2018

作者： Baksi, Ankita Niyogi, Jayita Guha Niyogi, Arup Guha Department of Architecture Women’s Polytechnic Kolkata Jodhpur Park 1/1/2 Gariahat Road KolkataWest Bengal700068 India Department of Architecture Jadavpur University KolkataWest Bengal700032 India Department of Civil Engineering Jadavpur University KolkataWest Bengal700032 India

ISBN: (纸本)9789811537417

Most of the Indian cities are suffering from rapid growth of traffic volume which causes disruptions in easy travel to the destinations. With the addition of informal public transport (IPT), these difficulties have multiplied. Rise in share of low passenger capacity IPT is increasing the passenger car units (PCU) on roads manifold. This, in turn, enhances delay, road density and pollution, while reducing speed. This paper aims to assess the problems caused by IPT and suggest strategies to control them in Kolkata. The busy Rashbehari and Hazra intersections of Kolkata are studied here, and some planning schemes are tested by restricting the IPT that results in overall reduction in the number of vehicles, PCU load, road density in that intersection. © 2020, Springer Nature Singapore Pte Ltd.

关键词： Travel time

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Experimental and numerical investigation of in-plane cyclic response of a point-fixed glass façade system for seismic performance assessment

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Journal of Building engineering 2025年 108卷

作者： Eliana Inca-Cabrera Sandra Jordão Carlos Rebelo Chiara Bedon Afonso Mesquita Seyed-Amin Hosseini University of Coimbra ISISE ARISE Department of Civil Engineering Coimbra Portugal University of Trieste UNITS Department of Engineering and Architecture Trieste Italy Polytechnic Institute of Castelo Branco IPCB Higher School of Technology Castelo Branco Portugal

This study investigates the seismic performance of point-fixed glass façade systems (PFGFS) through a full-scale experimental campaign conducted at the University of Coimbra. Two façade systems were tested, accounting for two fixing configurations: fully drilled countersunk bolts and partially through (embedded) bolts. Each system consisted of nine glass panels arranged in a 3 × 3 configuration, with individual panel dimensions of 1490 mm × 1490 mm. The façade systems were subjected to quasi-static cyclic loading to assess their in-plane drift response and post-fracture behaviour. Results indicate that failure initiated in the middle row, yet the façade system remained functional, sustaining additional loading cycles without complete failure. Maximum lateral drift ratios were 2.12 % for partially through bolts and 2.28 % for fully drilled bolts. Deformations were accommodated through rigid body motion, bolt rotation, and sealant relaxation, with washer yielding acting as a sacrificial mechanism to absorb deformation. The lamination foil played a crucial role in retaining shattered glass, ensuring post-failure integrity, and preventing the release of hazardous debris. A finite element model (FEM), validated against experimental results, successfully captured the façade's force-displacement response, confirming progressive failure behaviour. These findings highlight the ductility of point-fixed glass façade systems and demonstrate their capacity to sustain lateral displacement while maintaining structural stability. The results provide valuable insights into the deformation capacity of glass façades, enhancing the understanding of their safety and resilience in seismic regions.

关键词： In-plane drift Point-fixed glass façade Experimental tests FE-Modelling Seismic performance of non-structural elements

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Numerical Study of Pedestrian-Level Wind Environment Around Elevated Walkways and Influential Factors in Ideal Urban Street Canyons

SSRN

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SSRN 2023年

作者： Chen, Lan Mak, Cheuk Ming Hang, Jian Dai, Yuwei Niu, Jianlei Tse, Kam Tim Department of Building Environment and Energy Engineering The Hong Kong Polytechnic University Hung Hom Hong Kong School of Atmospheric Sciences Sun Yat-sen University Key Laboratory of Tropical Atmosphere-Ocean System Ministry of Education Zhuhai519000 China School of Environment and Architecture University of Shanghai for Science and Technology 516 Jungong Road Shanghai China Department of Civil and Environmental Engineering The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong

Constructing elevated walkway systems is an effective and prevalent strategy for densely populated cities to improve pedestrian walkability and road safety. Nevertheless, adding an elevated walkway inside the street will inevitably influence the local wind environment, which has rarely been investigated. This study aims to examine the pedestrian-level wind environment around the elevated walkway in three-dimensional (3D) ideal urban street canyons using large eddy simulations. The impacts of street aspect ratio (H/W = 1, 2, 3), elevated walkway width (Wew/W = 0.2, 0.4, 0.6), and sidewall type (open, semi-hermetic, hermetic) on the mean wind velocity, turbulence intensity, and gust wind velocity fields were quantified. Results indicate that the elevated walkway maintains 3D helically clockwise vortex structures in the street but alters flow regimes around it. After adding an elevated walkway, the pedestrian-level area-averaged mean and gust wind velocities decline for three aspect ratio cases, with a maximum rate of over 20% and 30%. The mean and gust wind velocities and turbulence intensity do not show a continuous varying trend with H/W. Extremely wide elevated walkways should be avoided as the pedestrian-level mean and gust wind velocities decrease with increased walkway width. Using semi-hermetic or hermetic sidewalls slightly improves the area-averaged mean and gust wind velocities but weakens turbulence intensity. This study promotes the knowledge of the impacts of elevated walkways, street aspect ratio, and walkway designs on pedestrian-level mean and gust wind environments, providing a scientific basis for further research. © 2023, The Authors. All rights reserved.

关键词： Aspect ratio

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Fluid Tunnel Research for Challenges of Urban Climate

arXiv

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arXiv 2023年

作者： Zhao, Yongling Chew, Lup Wai Fan, Yifan Gromke, Christof Hang, Jian Yu, Yichen Ricci, Alessio Zhang, Yan Xue, Yunpeng Fellini, Sofia Mirzaei, Parham A. Gao, Naiping Carpentieri, Matteo Salizzoni, Pietro Niu, Jianlei Carmeliet, Jan Department of Mechanical and Process Engineering ETH Zürich Switzerland Department of the Built Environment National University of Singapore Singapore College of Civil Engineering and Architecture Zhejiang University Zhejiang University China International Research Center for Green Building and Low-Carbon City Zhejiang University China Institute for Hydromechanics Karlsruhe Institute of Technology Germany School of Atmospheric Sciences Sun Yat-Sen University China Department of Building Environment and Energy Engineering Hong Kong Polytechnic University Hong Kong University School for Advanced Studies IUSS Italy Eindhoven University of Technology Netherlands Future Resilient Systems Singapore-ETH Centre ETH Zurich Singapore Univ Lyon INSA Lyon CNRS Ecole Centrale de Lyon Univ Claude Bernard Lyon 1 France Architecture & Built Environment Department University of Nottingham United Kingdom Department of Mechanical Engineering Tongji University China Department of Mechanical Engineering Sciences University of Surrey United Kingdom

Experimental investigations using wind and water tunnels have long been a staple of fluid mechanics research for a large number of applications. These experiments often single out a specific physical process to be investigated, while studies involving multiscale and multi-physics processes are rare due to the difficulty and complexity in the experimental setup. In the era of climate change, there is an increasing interest in innovative experimental studies in which fluid (wind and water) tunnels are employed for modelling multiscale, multi-physics phenomena of the urban climate. High-quality fluid tunnel measurements of urban-physics related phenomena are also much needed to facilitate the development and validation of advanced multi-physics numerical models. As a repository of knowledge in modelling these urban processes, we cover fundamentals, recommendations and guidelines for experimental design, recent advances and outlook on eight selected research areas, including (i) thermal buoyancy effects of urban airflows, (ii) aerodynamic and thermal effects of vegetation, (iii) radiative and convective heat fluxes over urban materials, (iv) influence of thermal stratification on land-atmosphere interactions, (v) pollutant dispersion, (vi) indoor and outdoor natural ventilation, (vii) wind thermal comfort, and (viii) urban winds over complex urban sites. Further, three main challenges, i.e., modelling of multi-physics, modelling of anthropogenic processes, and combined use of fluid tunnels, scaled outdoor and field measurements for urban climate studies, are discussed. © 2023, CC BY-NC-SA.

关键词： Urban growth

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Influences of elevated temperature on the passivation and depassivation properties of reinforcing steel in concrete environment

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Cement and Concrete Composites 2025年 163卷

作者： Chandra Sekhar Das Haibing Zheng Jian-Guo Dai Department of Civil and Environmental Engineering The Hong Kong Polytechnic University Hong Kong Institute of Chemistry Henan Academy of Sciences Zhengzhou 450046 China Department of Architecture and Civil Engineering City University of Hong Kong Hong Kong

Understanding the chloride threshold value (CTV) under various environmental conditions is essential for condition assessment and service life estimation of reinforced concrete (RC) structures susceptible to corrosion damage. This study investigates the influence of three exposure temperatures (25 °C, 35 °C and 45 °C) on the passivation and depassivation (i.e., corrosion initiation) of steel bars in a simulated concrete pore solution by employing different electrochemical measurements and surface characterization techniques. Results demonstrate that exposure to elevated temperatures accelerates the oxidation of the Fe metal, favouring Fe(III) oxide formation over Fe(II) oxides, as evidenced by a higher Fe(III)/Fe(II) ratio and nobler corrosion potentials. The net oxide content is also lower, with a higher concentration of defects, which reduces the overall protectiveness of passive film. Consequently, as chlorides were progressively added at the end of passivation (i.e., 14 days), the average CTV decreased sharply from 3.5 M at 25 °C to 1.9 M at 35 °C and 1.1 M at 45 °C. A temperature increase of 10 °C reduced the CTV by nearly 50 %, while a 20 °C rise reduced it to less than one-third of its initial value, highlighting the strong dependency of CTV on exposure temperature. Notably, irrespective of the exposure temperatures, the depassivation of the steel samples was triggered when polarization resistance dropped to the range of 500–600 kΩ∙cm 2 , and solution resistance was nearly 5 Ω∙cm 2 . These findings emphasize the need to reassess the corrosion risk in RC structures under different climate conditions to avoid overestimating service life.

关键词： Chloride threshold value Corrosion Passive film Steel reinforcement Temperature

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Causal effects estimation: Using natural experiments in observational field studies in building science

Indoor Environments

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Indoor Environments 2025年第1期2卷

作者： Ruiji Sun Stefano Schiavon Gail Brager Haiyan Yan Thomas Parkinson Center for the Built Environment University of California Berkeley USA Department of Architecture University of California Berkeley USA Department of Civil and Environmental Engineering University of California Berkeley USA School of Architecture and Artistic Design Henan Polytechnic University China IEQ Lab School of Architecture Design and Planning University of Sydney Australia

Correlational analysis, such as linear regression, does not imply causation. This paper introduces and applies a causal inference framework and a specific method, regression discontinuity, to thermal comfort field studies. The method utilizes policy thresholds in China, where the winter district heating policy is based on cities' geographical locations relative to the Huai River. The approximate latitude of the Huai River can be considered as a natural, geographical threshold, where cities near the threshold are quite similar, except for the availability of district heating in cities north of the threshold, creating a situation similar to a randomized experiment. Using the regression discontinuity method, we quantify the causal effects of the experiment treatment (district heating) on the physical indoor environments and subjective responses of building occupants. We found that mean indoor operative temperatures were 4.3 °C higher, and mean thermal sensation votes were 0.6 warmer due to the district heating. In contrast, using conventional correlational analysis, we demonstrate that the correlation between indoor operative temperature and thermal sensation votes does not accurately reflect the causal relationship between the two. We also show that the indoor operative temperature could be either positively or negatively correlated with occupants’ thermal satisfaction. However, we cannot conclude that increasing the indoor operative temperature in these circumstances will necessarily lead to higher or lower thermal satisfaction. This highlights the importance of causal inference methods in thermal comfort field studies and other observational studies in building science, where the regression discontinuity method might apply.

关键词： Causal inference Regression discontinuity Thermal comfort Field study District heating

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Effect of traffic tidal flow on pollutant dispersion in various street canyons and corresponding mitigation strategies

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Energy and Built Environment 2020年第3期1卷 242-253页

作者： Zhengtong Li Tianhao Shi Yongjia Wu Hao Zhang Yu-Hsuan Juan Tingzhen Ming Nan Zhou Department of Mechanical Engineering The Hong Kong Polytechnic UniversityKowloonHong Kong SARChina School of Civil Engineering and Architecture Wuhan University of TechnologyWuhanChina Department of the Built Environment Eindhoven University of TechnologyEindhoventhe Netherlands China Energy Group Environmental Energy Technologies DivisionLawrence Berkeley National Laboratory1 Cyclotron RoadBerkeleyCA 94720USA

Increasing traffic emission presents a high risk of exposure to residents in near-road *** tidal flow(TTF)has gradually become one of the most important components of urban traffic *** computational fluid dynamics simulation,the present study examines the airflow,spatial distribution of pollutant concentration,and personal intake fraction(IF_p)of CO in five street canyon structures(shallow,regular,deep,step-up,and step-down street canyons),with non-uniform TTF-induced traffic emission *** urban design devices(wind catchers)are subsequently introduced to reduce IF_*** results suggest that leeward IF_p is far higher in concentration than the windward wall in the shallow,regular,step-up,and step-down street canyons but lower than the windward side in the deep street canyon under different TTF ***,the TTF condition S L(leeward source)/S W(windward source)=3/1 leads to a higher leeward IF_p in the shallow,regular,deep,and step-up street canyons,compared with S L/S W=1/3;however,no significant difference in windward IF_p is found under the different TTF *** highest IF_p and lowest IF_p for both TTF configurations occur in the step-down and shallow street canyons,***,the effect of wind catchers(WCs)varies between the street canyon structures under different TTF *** can lead to at least 30.6%reduction in leeward overall average IF_p()in the shallow,regular,step-up,and step-down street canyons,as well as 12.8%-78.4%decrease in windwardowing to the WCs in the regular,deep,step-up,and step-down street canyons.

关键词： Street canyon Intake fraction Computational fluid dynamics(CFD) Wind catchers

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