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Ventilation schemes for high-temperature buoyancy-driven plumes from spherical surfaces of a large-scale experimental facility

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Energy and Built Environment 2020年第3期1卷 262-277页

作者： Wenxuan Zhao Wei Ye Yu Xue Chao Wu Xu Zhang School of Mechanical Engineering Tongji UniversityShanghai 201804PR China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji UniversityShanghai 200092PR China

A large-scale sphere-shaped experimental facility for neutrino detection is designed as a 23-latitudinal layer composite by using organic glass as the major raw material and is assembled via mass polymerization through a top-to-bottom *** belts at 4200 W/m 2 are used to anneal the bonding joints of external and internal spherical surfaces and produce high-temperature thermal ***-driven plumes should be effectively mitigated using ventilation to ensure the near-surface air temperatures above the finished layers can be delicately controlled within 21±1℃to minimize the deformation of the *** to control plumes on both surfaces were investigated using Computational Fluid Dynamics(CFD)method by following a performance-based ***,an independent field study was conducted to measure surface temperature and heat flux of mass polymerization and provide references for ***,dynamic buoyancy-driven plumes pro-duced along the external and internal spherical surfaces were simulated under a no-ventilation *** contacting with the plumes,three periods,in which buoyancy,convection,and advection,were dominating,can be observed according to the changes of near-surface air ***,the temperature and Ra num-ber of the surface-attached plumes were used as indicators to assess the intensity of the plumes ***,three major ventilation schemes,i.e.,general,push-pull,and sphere-attached ventilations(with three sub-designs),were compared under the same air change rate level on the basis of the following perspectives:(1)air temperature distributions above the polymerizing layer,(2)overall heat exhaust efficiency,and(3)total spaces where temperature was higher than 22℃.Results indicated that the combination of push-pull and side-supply ventilations,by which the heat exhaust efficiencies were up to 1.87-3.24,was found to be most effective to control thermal plumes,with approximately 0.1%of the tota

关键词： Computational fluid dynamics Neutrino detector Heat flux Push-pull Buoyancy-driven

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The application of water jet technology on concrete: A review

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Journal of Building engineering 2025年 108卷

作者： Pan, Chao Zhao, Zengfeng Lin, Can Yao, Lei Xiao, Jianzhuang Tošić, Nikola 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 Institute of Science and Technology for Carbon Peak & Neutrality Guangxi University Nanning530004 China Civil and Environmental Engineering Department Universitat Politècnica de Catalunya Jordi Girona 1-3 Barcelona08034 Spain

The application of water jet technology on concrete has garnered widespread attention, as water jetting is an advanced technique with several unique advantages, including the absence of heat generation, high-efficiency material removal, and selective separation of materials. These benefits provide a solid foundation for its use in concrete applications. This study aims to review the existing literature (more than 160 references) on the application of water jet technology on concrete and discuss the limitations of current techniques. Based on various practical scenarios, this study divided the research and applications of water jet technology on concrete into three main categories: crushing, granulation, and surface treatment. Crushing involves the controlled erosion and removal of concrete using the impact kinetic energy of the water jet. Granulation refers to the process of liberating coarse and fine recycled aggregates from waste concrete, leveraging the differing impact resistances of aggregates and cementitious materials. Surface treatment consists of using water jet to remove impurities and discarded parts from the concrete surface, thereby improving its surface properties. Water jet input parameters (e.g. water jet pressure, nozzle traverse speed, standoff distance, different forms of water jet) and concrete properties (e.g. compressive strength, steel or fiber content) could affect the crushing efficiency and surface roughness. The findings provide inspirational insights for engineers, designers, and industry stakeholders to overcome technical challenges in construction engineering and further promote the application of water jet technology on concrete. © 2025 Elsevier Ltd

关键词： Granulation

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How does the control logic influence the establishment of a data-driven chiller model?

How does the control logic influence the establishment of a ...

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2021 International Conference on Computer, Remote Sensing and Aerospace, CRSA 2021

作者： Qiu, Shunian Li, Zhenhai He, Ruikai Li, Jiajie Li, Zhengwei School of Mechanical Engineering Tongji University Shanghai Shanghai201804 China China Academy of Building Research Beijing Beijing100013 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai Shanghai201804 China

The modelling of chiller performance is critical for chiller optimal control, and fault detection and diagnosis (FDD). Different kinds of chiller models including sophisticated mechanistic models (white-box models), purely data-driven models (black-box models like artificial neural networks, ANN), and semi-physical models (grey-box models like empirical equations) have been proposed and tested. Due to the development of machine learning techniques, data-driven models have become more popular recently. The performance of the established data-driven model (accuracy, robustness, generalization) could significantly affect the model application. To enhance the model performance, a lot of studies have been carried out on investigating and modifying the model structure. However, the influence of the data quality on model training has not been sufficiently studied. When adopting historical data to train models, the data distribution is highly correlated to the control logic. So how does the control logic influence the establishment of data-driven chiller models by affecting the data distribution? In this study, experiments are conducted on an air-cooled chiller under model-free stochastic control to acquire rich and variable operational dataset;then the dataset is grouped into three corresponding to different chiller control logics. Finally, three models trained by three training datasets are evaluated, and the results suggest that when establishing data-driven chiller models, preliminary stochastic operation is cost-effective to acquire rich data for robust chiller modelling. © 2021 Institute of Physics Publishing. All rights reserved.

关键词： Neural networks

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Real-Time Cable Force Identification Based on Block Recursive Capon Spectral Estimation Method

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SSRN 2022年

作者： Yu, Xuewen Dan, Danhui School of Civil Engineering Tongji University 1239 Road Shanghai200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures Ministry of Education Tongji University 1239 Road Shanghai200092 China

Cables are critical force-bearing components of cable-supported structures that greatly influence structure security. The changes in cable forces can reflect the cable service state and provide an important basis for structural health assessment. This paper proposes a method for real-time cable force identification (CFI) to tacking its varying rules. First, a recursive Capon method based on block updating is derived to estimate the amplitude spectrum at each observation moment. Second, determine the natural frequency (and corresponding mode order) in the transformed frequency domain and calculate the cable tension force according to related formulas. Proper algorithm optimization and parameter selection are studied to ensure that the calculation cost meets the real-time requirement of CFI. The proposed method is applied to an experimental cable and the cables of an arch bridge for validation. © 2022, The Authors. All rights reserved.

关键词： Frequency domain analysis

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Precision temperature control for an irregular cavity with internal heat source on a large-scale scientific facility using CFD simulations 16

Precision temperature control for an irregular cavity with i...

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16th Conference of the International Society of Indoor Air Quality and Climate: Creative and Smart Solutions for Better Built Environments, Indoor Air 2020

作者： Xue, Yu Zhao, Wenxuan Ye, Wei Wu, Chao Zhang, Xu School of Mechanical Engineering Tongji University China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University China

ISBN: (纸本)9781713823605

A spherical experimental facility with a diameter of 35.4m for neutrino detection is located in a cylindrical underground laboratory. The photomultiplier tubes on the surface of the facility would generate heat at 200kW. And the spherical plexiglass inside the device is at risk of cracking due to drastic temperature changes. A low-flow-rate circulation system using water is developed in this paper, to keep the temperature around the sphere within 21±1℃. Using CFD, the effects of the design parameters of the water circulating system, e.g., water distribution angle (A), supplying velocity (V), etc., on water temperature are quantified. The results show that, first, the temperature of the inner water layer can be better controlled when the A is small, while the overall temperature is better controlled when A is large. Second, when V varies between 0.2 m/s and 0.4 m/s, no significantly effects on water temperature distributions are observed. © 2020 16th Conference of the International Society of Indoor Air Quality and Climate: Creative and Smart Solutions for Better Built Environments, Indoor Air 2020. All rights reserved.

关键词： Water temperature

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Numerical simulation of compact-tension specimens repaired by CFRP

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Procedia Structural Integrity 2023年 45卷 96-103页

作者： Yuanpeng Zheng Tao Chen Cheng Huang Weijian Wu Key Laboratory of Performance Evolution and Control for Engineering Structures (Ministry of Education) Tongji University Shanghai 200092 China Department of Structural Engineering Tongji University Shanghai 200092 China Department of Civil and Environmental Engineering Imperial College London London SW7 2AZ United Kingdom Department of Civil and Mechanical Engineering Technical University of Denmark Lyngby 2800 Kgs. Denmark

Carbon fiber reinforced polymer (CFRP) reinforcement is emerging as an efficient means of elongating the service life of cracked metallic structures. An experimental program was conducted to investigate the fatigue behavior of compact-tension (CT) specimens repaired by different CFRP configurations. In parallel, numerical simulations of the fatigue crack growth in the CFRP-repaired specimens were also conducted. The eXtended finite element method (XFEM) was employed and shown to provide accurate and efficient calculations of the stress intensity factor (SIF), without remeshing the models during crack propagation. The mechanical properties of the adhesive were simulated using a cohesive traction-separation relationship. Good agreement was observed between the numerical and experimental results of the SIF and fatigue life, with the latter numerically predicted based on the experimentally derived Paris law constants. Insight into the debonding behavior between the CFRP and steel specimens has also been provided. Due allowance for the weakening effect of damage initiation and evolution between the FRP-steel interfaces is required in the reinforcement calculations.

关键词： CFRP compact-tension specimen fatigue crack growth rate (FCGR) stress intensity factor (SIF), traction-separation relationship

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Study on Axial Compression Properties of Concrete Columns Wrapped with Basalt Textile-Reinforced Fine Concrete (Btrc) Jacket

SSRN

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SSRN 2022年

作者： Zhang, Qin Yang, Qiaochu Gu, Xianglin Jiang, Yong College of Civil and Transportation Engineering Hohai University Nanjing210024 China Key Laboratory of Performance Evolution and Control for Engineering Structures Ministry of Education Tongji University 1239 Siping Rd Shanghai200092 China

A total of 20 column specimens were prepared for axial compressive tests to investigate the compressive behavior of the concrete column (including plain concrete column and reinforced concrete column) and were wrapped with a basalt textile-reinforced fine concrete (BTRC) jacket. Four parameters including the number of textile layers, stirrup spacing, core concrete strength, and the use of short fibers were considered and evaluated. The results indicate that the bearing capacity and the displacement ductility of the columns were clearly improved with an increase in the number of textile layers. For the BTRC-strengthened columns, as the number of textile layers increased from 0 to 2, 3, and 4, the bearing capacity increased by 33.2%, 39.0%, and 46.9%, respectively. Moreover, the improvement in the bearing capacity and deformation energy was affected by core concrete strength. Columns with lower concrete strength obtained a more effective increment. Additionally, short fibers also played an important role in improving the compressive behavior of the columns. Finally, the available experimental data on BTRC-confined concrete columns was compiled, and an analytical model was proposed based on the test results in this study and other studies to predict the stress-strain relationship of BTRC-confined concrete under axial compressive load. The stress-strain curves of BTRC-confined concrete predicted by the analytical model agreed strongly with the experimental curves, proving the model proposed in this study can be used to predict the stress-strain relationship of BTRC-confined concrete. © 2022, The Authors. All rights reserved.

关键词： Basalt

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3d Morphology Reconstruction-Based Modelling and Mechanical Degradation Study of Corroded Low Alloy Steel Specimens

SSRN

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SSRN 2023年

作者： Xu, Lichao Ruan, Xin Fang, Tao Wei, Yi Li, Yue Department of Bridge Engineering Tongji University 1239 Siping Road Shanghai20092 China Key Laboratory of Performance Evolution and Control for Engineering Structures Tongji University 1239 Siping Road Shanghai20092 China Anhui Transportation Holding Group Co. Ltd. Anhui China

The evolution law in surface morphology of low alloy steel after corrosion was investigated through accelerated corrosion test in this paper. Specimens with varying corroded levels were parametrically reconstructed based on their fractal features. The influence of morphology on mechanical degradation was quantified based on uniaxial tensile simulation, and the accuracy was assessed by comparison with existing test. The analysis results indicate that the morphology of corroded steel has significant additional adverse effects on its nominal mechanical properties and can reach 15% maximum on yield strength, which cannot be reflected by traditional methods that only considers corrosion-induced section reduction. © 2023, The Authors. All rights reserved.

关键词： Alloy steel

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An Investigation of Stress Analysis Via Finite Element Method in Compacted Snow Runways

SSRN

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SSRN 2024年

作者： Chen, Tao Ji, Lin Xiao, Enzhao Jiang, Chao Huang, Qinghua Gu, Xiang Lin Qiao, Gang Key Laboratory of Performance Evolution and Control for Engineering Structures Ministry of Education Tongji University Shanghai200092 China Department of Structural Engineering Tongji University Shanghai200092 China R & D Division of Polar Snow and Ice Runways Polar Research Institute of China Shanghai200136 China College of Surveying and Geo-Informatics Tongji University Shanghai200092 China

Compacted snow runway for heavy wheeled aircraft is challenging in polar regions and future possible extraterrestrial infrastructure construction. Finite element method was successfully employed to simulate wheel landing on layered snow by ABAQUS software package based on Phoenix runway in Antarctica. Firstly, the method is validated with theoretical results of several layered system. Thereafter, basic parameters of snow were chosen with refer to Phoenix runway pavement. Stress distributions under landing gear were calculated for the C17, A319, B757 and Il-76 aircrafts. Furthermore, the effect of subgrades on stress distributions were discussed. Current study can explore our knowledge on snow pavements. It can also provide technical supports for design and construction of compacted snow runways. © 2024, The Authors. All rights reserved.

关键词： Finite element method

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Oligo (Ethylene Glycol) Side Chain engineering: An Efficient Way for Boosting the Development of Green-Solvent Processable Electrochromic Devices

SSRN

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SSRN 2023年

作者： Li, Shiyi Wang, Qilin Zhai, Yuehui Xing, Zhen Zhong, Jundong Chao, Danming Zhu, Xuanbo Rong, Changru Wu, Zongquan Chen, Zheng National and Local Joint Engineering Laboratory for Synthetic Technology of High-Performance Polymer College of Chemistry Jilin University Changchun130012 China State Key Laboratory of Supramolecular Structure and Materials College of Chemistry Jilin University Changchun130012 China National Key Laboratory of Advanced Vehicle Integration and Control China FAW Group Co. Ltd. Changchun130013 China

As an effective strategy for improving the performance of optoelectronic polymers, oligo (ethylene glycol) (OEG) side chain engineering has been widely used in optoelectronic materials field. However, the research on its impact on electrochromic (EC) polymers started to be explored in recent years. In this work, the excellent EC properties of the star polymer PTQ-10 were first investigated and proved. Subsequently, a series of novel PTQ-type polymers with OEG side chains (PTQ-OEGs) were successfully synthesized and studied. Compared with PTQ-10, the introduction of OEG side chains can significantly shorten the coloring time (~82.2%) and improve the coloration efficiency (~17.0%). Notably, the solubility of PTQ-OEGs is greatly enhanced in ideal green solvents (alcohol) via introducing the OEG side chains. Therefore, the EC active layers of PTQ-BTEG can be simply fabricated by its ethanol solution. Based on this feature, an all-green EC device PTQ-BTEG@ECD-2 (from material processing to device preparation) was prepared successfully, which exhibited fast coloring (3.41 s) and bleaching (13.17 s) as well as high coloration efficiency (396.12 cm2 C-1). Hence, we not only reported the relationship between OEGs and EC polymers thoroughly, but also proved the OEG engineering is a practical approach to promote the development of all-green EC devices in the near future. © 2023, The Authors. All rights reserved.

关键词： Conjugated polymers

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