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Balancing the piezoelectric coefficient and carrier concentration of Bi_(2)WO_(6−x) for ultrahigh piezocatalysis

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Journal of Advanced Ceramics 2024年第11期13卷 1737-1747页

作者： Ying Wang Xiaoli Xu Lingbo Xiao Lutao Li Qiuhua Xu Zhenhai Wen Laishun Qin Yanmin Jia Dong-Liang Peng Wanping Chen Da Chen College of Materials and Chemistry China Jiliang UniversityHangzhou 310018China Key Laboratory of Jiangxi Province for Persistent Pollutants Control National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization and Resources RecycleNanchang Hangkong UniversityNanchang 330063China Department of Physics Zhejiang University of Science and TechnologyHangzhou 310008China Jiangsu Key Laboratory for Science and Applications of Molecular Ferroelectrics Southeast UniversityNanjing 211189China Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province College of EnergySoochow UniversitySuzhou 215006China State Key Laboratory of Structural Chemistry and Fujian Provincial Key Laboratory of Materials and Techniques toward Hydrogen EnergyFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China School of Physics and Information Technology Shaanxi Normal UniversityXi’an 710121China State Key Laboratory of Physical Chemistry of Solid Surface Fujian Key Laboratory of Surface and Interface Engineering for High Performance MaterialsCollege of MaterialsXiamen UniversityXiamen 361005China School of Physics and Technology Wuhan UniversityWuhan 430072China

Balancing the piezoelectric coefficient and carrier concentration of materials is key in the field of *** this work,Bi_(2)WO_(6) material with both piezoelectric and semiconductor properties was chosen as a model material.A one-step ethylene glycol(EG)-assisted solvothermal method was used to synthesize Bi2WO6 with oxygen *** controlling the solvothermal time and temperature,the oxygen vacancy concentration(COV)was *** COV increases,the piezoelectric coefficient decreases,the carrier concentration increases,and the hydrogen production rate first increases but then *** COV reaches 1.45×10^(12) spins·mg^(−1),the corresponding piezoelectric coefficient and carrier concentration are 13.9 pm·V^(−1) and 2.90×10^(20) cm^(−3),*** optimal hydrogen production rate per power of 2.21μmol·g^(−1)·h^(−1)·W^(−1) is equivalent to or even better than that of most reported *** piezoelectric coefficient and carrier concentration,as two factors,jointly determine the piezocatalytic *** findings of this research can provide important and deep-seated insights for better piezocatalysts in the future.

关键词： piezocatalysis oxygen vacancy carrier concentration piezoelectric coefficient hydrogen evolution

Investigating Toothbrushing Behavior and its Aerosol Emissions from Using Electric Toothbrushes

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SSRN 2023年

作者： Tang, Wenhao Li, Yiqun Ye, We School of Mechanical Engineering Tongji University Shanghai201804 China Key Laboratory of Engineering Structure Performance Evolution and Control Ministry of Education Tongji University Shanghai200092 China

The human oral cavity has been recognized as a significant source of particles that can cause respiratory infectious diseases. In recent years, electric toothbrushes are gaining popularity as a cleaning product in people's life. The working principle of the electric toothbrushes involves high-frequency vibration, which can, in theory, spread droplets or small-size aerosols containing viruses. However, the particle emission rates and the potential to spread respiratory diseases using electric toothbrushes are still unclear. In this paper, we investigated the particle emissions from using electric toothbrushes by designing a three-step approach, i.e., a preference survey on toothpaste and toothbrush selections, a behavior test on toothpaste usage, and a standardized particle emission test using a mechanical arm to hold an electric toothbrush to brush fabricated teeth of an oral cavity model. The results showed that, first, the toothpaste would be rapidly decomposed into foams and the emission rates quickly increased to a peak within approximately 10s. Then, the particle emissions decreased slightly and entered a steady phase until the 2-min brushing period stopped. Second, the emitted particles mainly were PM5, which can be considered aerosols, and the emissions can reach up to 5433 counts/s. Third, the effects of toothpaste usage on aerosol emissions were insignificant. Meanwhile, the emissions heavily depended on toothbrush and toothpaste selections, the brushing post, i.e., the teeth. Furthermore, the particle concentrations around the cavity produced by electric toothbrushes were approximately one to two orders of magnitude greater than breathing, talking, and singing and were smaller than coughing. © 2023, The Authors. All rights reserved.

关键词： Aerosols

Pre-Relaxed Cables for Improving Progressive Collapse Resistance of Rc Frame Subassemblages Considering Slabs

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SSRN 2024年

作者： Qiu, Lu Lin, Feng Yang, Xing-Ju Department of Structural Engineering Tongji University Shanghai200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Shanghai200092 China

A common method to improve the progressive collapse resistance of reinforced concrete (RC) frame structures is to increase the reinforcements in beams, which might result in the undesired failure mode of strong beam-weak column for the structures under earthquakes. To improve the progressive collapse resistance of the RC frame structures without affecting their seismic behaviors, a novel retrofit has been proposed using pre-relaxed cables. This study investigated the improvement of the pre-relaxed cables on the progressive collapse resistance of the RC frame structures considering the presence of the slabs subjected to the distributed loads. A quasi-static test was carried out on two one-quarter scaled 2[[EQUATION]]2-bay subassemblages, i.e., a beam-slab (BS) subassemblage and a beam-slab-cable (BS-cable) subassemblage. Experimental results found that the progressive collapse resistance and deformation capacity of the BS-cable subassemblage was 55% and 260% larger than those of the BS subassemblage, respectively. The resistance improvement mechanism of the BS-cable subassemblages was revealed, i.e., the tensile catenary action in the beams, tensile membrane action in the slabs, and tension action in the cables. The finite element (FE) models were then developed, validated against the experimental results, and used for parametric studies with the consideration of the cable diameter and cable original length. Numerical results found that there were two failure modes for the BS-cable subassemblages, i.e., beam failure mode and slab failure mode. The limited maximum value of the resistance improvement is critically related to the failure mode. For the beam failure mode, the increase in the cable diameter could improve the progressive collapse resistance until the slab failure mode occurred. © 2024, The Authors. All rights reserved.

关键词： Structural dynamics

Long-term effects of electrochemical realkalization on carbonated concrete

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Frontiers of Structural and Civil engineering 2020年第1期14卷 127-137页

作者： Peng ZHU Ji ZHANG Wenjun QU College of Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Performance Evolution and Control for Engineering Structures Shanghai 200092China

The long-term effects of electrochemical realkalization on carbonated reinforced concrete with a W/C ratio of 0.65 were *** out of 16 carbonated specimens had been subjected to realkalization seven years ago,and the alkalinity of the concrete,the electrochemical characters(corrosion current density and potential)of the specimens and the corrosion conditions of the steel bars were *** of different specimens and also at different time(4,10,13 months and 7 years after realkalization)were *** to the phenolphthalein and pH meter test,the alkalinity of the concrete had disappeared after seven *** on the potentiodynamic polarization test,various corrosion conditions had developed on the steel bars,which was verified by visual *** bars were in the depassivated state,and their corrosion current densities increased significantly after seven *** developed in some of the specimens,and the diverse compactness of concrete and excessive current of realkalization were considered to be possible *** effects of the realkalization treatment vanished after seven years.

关键词： realkalization concrete carbonation polarization curve corrosion

An Experimental Investigation on Innovative Bolted Glulam Beam-to-Column Connections for Progressive Collapse Resistance

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SSRN 2024年

作者： Zhao, Xue-Bing Song, Xiao-Bin Tang, Jian-Yang Department of Structural Engineering College of Civil Engineering Tongji University Shanghai 200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai 200092 China.

This paper aims to enhance the structural progressive collapse resistance by optimizing the connection performance under large deformation. Two innovative bolted glulam beam-to-column connections were designed: one with supplementary bolts and another with supplementary hold-downs. To replicate the large deformation conditions of the progressive collapse, monotonic tests featuring the coupling effects of tension and bending were performed on four groups of specimens, including the standard bolted glulam beam-to-column connection, the self-tapping screws reinforced connection, and two novel ones. The typical failure modes, moment-rotation behavior, and primary performance parameters were analyzed. Then, three quantitative indexes of rotational performance under large deformation were established to evaluate the improved connections. The results demonstrate that the connection with supplementary bolts exhibits superior progressive collapse resistance, with moment capacity and maximum rotational angle that are 158% and 56%, respectively, greater than those of the standard one. In addition, although the connection with supplementary hold-downs presents a modest increase in rotational angles, it shows the highest improvement rates in initial and effective stiffness, 12% and 71% greater than the standard one, respectively. Moreover, compared with the standard connection, the ductility of the self-tapping screws reinforced connection has increased by 28%. In conclusion, simplified calculations for the moment capacity were developed. This study could provide references for the application of novel connections, thereby potentially enhancing the progressive collapse resistance of mass timber frame structures. © 2024, The Authors. All rights reserved.

关键词： Bending tests

Transfer Reinforcement Learning for Cooling Water System Optimization

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SSRN 2023年

作者： Wang, Zhechao Li, Zhengwei Cai, Wenxia School of Mechanical Engineering Tongji University Shanghai China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai China

In recent years, advanced control strategies based on reinforcement learning (RL) provides an effective and promising class of algorithms for optimizing the management of energy systems in buildings, enhancing energy efficiencies, and improving indoor comfort conditions when compared to traditional feedback controllers. Above all, model-free RL helps heating, ventilation, and air-conditioning (HVAC) optimizations git rid of building a detailed and comprehensive physics-based model. However, due to the re-training in each new system and the exploration by trial and error, it remains significantly time-consuming and laborious. These challenges are addressed in the literature on transfer RL, transferring a trained RL agent to other new systems. However, there are two main critical issues to be dealt with: (1) the strict conditions required by transferability and the complicated development programs, and (2) the inflexible and conservative agent structures refusing probable expert knowledge. In this paper, we introduce a framework focusing on a set of consistent input and output structures. Without complicated preparations, we provide a self-adaptive state mapping and a flexible action mapping among diverse systems by straightforward extending the input and output processes. Our framework is suitable for all RL algorithms with discrete controls and is friendly to on-site equipment operators. To compare with the ordinary RL learning from scratch, we conduct transfer experiments in summer data and winter data and attain 0.5% and 1.0% of the initial COP improvement and 80% and 86.6% of the convergence speed improvement, respectively. © 2023, The Authors. All rights reserved.

关键词： Reinforcement learning

Nondestructive quantitative estimation of cross-sectional corrosion degree of rebar using self-magnetic flux leakage field variation

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arXiv

arXiv 2025年

作者： Qiu, Junli Zhang, Weiping Jiang, Chao Zhang, Hong Zhou, Jianting State Key Laboratory of Mountain Bridge and Tunnel Engineering Chongqing Jiaotong University Chongqing400074 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University 1239 Siping Road Shanghai200092 China Department of Structural Engineering College of Civil Engineering Tongji University 1239 Siping Road Shanghai200092 China

To accurately assess the structural performance of corroded reinforced concrete structures, obtaining precise information on the corrosion range and corrosion degree of rebar is crucial. In this study, based on a comprehensive analysis of extensive high-precision magnetic field and three-dimensional structural light scanning data of 21 corroded rebars, it was found that the self-magnetic flux leakage can accurately identify the corrosion range, with an error not exceeding 3%. A proposed quantitative index NHx of the self-magnetic flux leakage amplitude exhibits a linear correlation with the cross-sectional corrosion degree of rebar, whose probability density distribution can be accurately described using the Weibull distribution function. Utilizing the Weibull distribution function of NHx and a Bayesian model, automatically rapid quantification of the rebar's cross-sectional corrosion degree based on the non-destructive testing-derived NHx values can be conveniently realized. This self-magnetic flux leakage-based novel method for quantifying rebar's cross-sectional corrosion degree is accurate, efficient, and well-suited for practical engineering applications, providing robust support for a precise assessment of the structural performance of corroded reinforced concrete structures. © 2025, CC BY-NC-ND.

关键词： Distribution functions

Optimization and evaluation of a solar energy, heat pump and desiccant wheel hybrid system in a nearly zero energy building

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建筑模拟（英文版） 2020年第6期13卷 1291-1303页

作者： Shaochen Tian Xing Su Xiaolu Shao Lei Wang School of Mechanical Engineering Tongji University Shanghai 200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai 200092 China

Traditional conventional air conditioners (CACs) are not applicable to nearly zero energy buildings (NZEBs), especially for residential buildings in regions with a humid climate in China. On the one hand, indoor thermal environment can be significantly affected in buildings by adopting insulations with higher thermal resistance and air tightness. On the other hand, CACs may not be able to meet the energy requirement of NZEBs when dehumidification is in high demand. Therefore, in this paper, a novel hybrid system, which featured solar panel, a multi-evaporator and multi-condenser heat pump, and a desiccant wheel, i.e., the SHDW system was proposed. The evaporator is for pre-cooling, and the desiccant wheel (DW) for handling the whole moisture load. The regeneration air of DW is heated by heat recovery condenser and the solar panel. By varying the evaporation temperature of HP, the energy performance was evaluated, and compared with that of a typical CAC, for controlling indoor temperature and humidity of a residential NZEB, using TRNSYS. The simulations were conducted for Shanghai (in a humid climate) in summer (July and August) and the transition seasons (June and September). The results showed that, first, the optimized evaporation temperature of the system is determined to be 12 °C and 9 °C, respectively, on a typical day both in summer and the transition seasons. Second, the daily coefficient of performances are 3.4 and 2.4 in summer and in transition seasons, ***, compared to either the temperature or humidity control mode of the CAC, the proposed SHDW system showed better promise for achieving indoor thermal comfort for residential NZEBs, especially in transition seasons. In a typical weekend, the daily energy consumption of the proposed SHDW system is 9.0％ and 12.3％ lower than that of the CAC with humidity control mode, respectively, in summer and the transition seasons.

关键词： desiccant wheel solar energy heat pump nearly zero energy building humid environment

Design Guidelines for Staged Desiccant Wheel with Type-S Isotherms: A Steady-State Cycle Analysis

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SSRN 2023年

作者： Li, Zhenglong Tao, Ruiyang Tang, Fangzhou School of Mechanical Engineering Tongji University Shanghai201800 China Key Laboratory of Performance Evolution and Control for Engineering Structures Ministry of EducationUniversity Tongji University Shanghai200092 China School of Electronics Peking University Beijing100871 China

A staged adsorption/desorption desiccant wheel employing solid desiccants with "S" shaped isotherms is a promising new concept for achieving efficient and effective dehumidification. However, its parameter optimization is challenging due to the many variables and the high degree of freedom associated with the desiccant combination and length design. Based on the thermodynamic analysis, this study recommended three engineering guidelines for standard design conditions and the arrangement of desiccants in staged wheels . Applying under 6 conditions, the corresponding desiccant wheels with optimized stage configuration exhibited substantially increased dehumidification potential requiring 10~20℃ lower *** (regeneration temperature) than traditional single-stage wheels. The results promote the development of the staged solid desiccant dehumidification system. © 2023, The Authors. All rights reserved.

关键词： Wheels