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13th REHVA World Congress, CLIMA 2019

作者： Zhi, Chengqiang Ye, Wei Zhang, Qianru Huang, Yixiang Zhang, Xu 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

Heavy trucks, train carriages, and other moving vehicles with heating sources, are often loaded into a confined space for parking and maintenance. When the heating source from the vehicle is at high temperature, spray cooling using nozzles can be applied for at least two purposes. First, to further decrease the temperature of the surrounding areas. Second, to flush the surfaces of the vehicle as a primary cleansing method. To reduce water consumption, the number and positions of the running nozzles along the way need to be adjusted and optimized according to the position of the moving vehicle. To achieve that, the optimization of a segmented control method for the nozzles is discussed using both theoretical and computational fluid dynamics (CFD) methods in this paper. 120 ~ 240 nozzles in total were uniformly and linearly distributed on the ceiling of a 120m-long narrow space. The space between two adjacent nozzles are set at 0.5m, 0.7m and 1.0m, respectively. All the nozzles are divided into one to ten groups for segmentation control. One 35m-long vehicle with a heating source at over 800 K was moving at 0.05 m/s to 0.20 m/s. The results showed that, first, for one spraying group, at least 39 running nozzles were needed to minimize the areas of interior structure at temperature > 350K. Second, the water consumption can be reduced dramatically by increasing the number of groups. However, when dividing into more than six groups, the capacity of water saving is no longer significant. Third, when the vehicle is entering, multiple-group of running nozzles are needed to overcome the sudden heating source at high temperature. © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0

关键词： Heating

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A comparative study for the impact performance of shaped charge JET on UHPC targets

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Defence Technology（防务技术） 2019年第4期15卷 506-518页

作者： Hao Wu Feng Hu Qin Fang Research Institute of Structural Engineering and Disaster Reduction 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 Research Institute for National Defense Engineering of Academy of Military Sciences PLA Beijing 100091 China Amy Engineering University of PLA Nanjing 210007 China

With the development of two-stage munitions(a precursor shaped charge(SC)and a following kinetic energy projectile)to attack the hard concrete targets,as well as the increasing applications of ultra-high performance concrete(UHPC)in both civil and military protective structures,a comparative study on the impact performance of SC formed jet on UHPC target is performed experimentally and numerically at ***,a series of jet penetration/perforation test on the UHPC,45# steel and UHPC/45# steel composite targets are *** assessing the penetration depth and borehole(crater and tunnel)diameter,the influences of target material and configuration as well as the standoff distance of SC on the impact performance of jet are experimentally ***,by adopting the 2 D multi-material Arbitrary Lagrange-Euler(ALE)algorithm,Fluid-structure Interaction(FSI)method and erosion algorithm implemented in the finite element code LS-DYNA,the formation and impact performance of jet in the present test are well ***,based on the validated numerical algorithms,constitutive models and the corresponding parameters,the influences of target material(UHPC,NSC and 45# steel),standoff distance,target configuration(stacked and spaced)and weight efficiency on the impact performance of jet are further *** derived conclusions could provide helpful references for evaluating the ballistic performance of jet and designing the protective structures.

关键词： Shaped charge jet Ultra-high performance concrete Penetration Perforation Numerical simulation

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Stability of cable-stiffened aluminum reticulated shells considering joint bending and shear flexibility

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Journal of Constructional Steel Research 2025年 234卷

作者： Ping Xiang Zifei Li Mingzhe Shi Minger Wu Dept. of Structural Engineering College of Civil Engineering Tongji University No. 1239 Siping Road Shanghai 200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Shanghai 200092 China China Nuclear E&C Group Innovation Technology Co. Ltd Shanghai 201702 China

This study investigates cable-stiffened aluminum alloy reticulated shells that employ two-way aluminum alloy gusset joints (AAGJs) as their joint systems. AAGJs are typical semi-rigid joints with ambiguous shear performance. Bending moment-rotational angle curves and load-shear angle curves obtained from previous experiments are used to describe the bending and shear behavior of the joint, respectively. A strut-and-tie model representing a simplified AAGJ is proposed, and its efficiency is investigated. A parametric study of shells with different cable arrangements, spans, rise-to-span ratios, beam length and joint stiffness is conducted, where it is found that pre-tension cables can improve the stability of the shell and reduce its sensitivity to joint flexibility, and shear performance of joints has limited influence on the stability of the overall structure.

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Simulations on arrangements of induced jet-fans as auxiliary ventilation for a mechanical ventilated space with openings 13

Simulations on arrangements of induced jet-fans as auxiliary...

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13th REHVA World Congress, CLIMA 2019

作者： Zhao, Wenxuan Ye, Wei Zhang, Qianru Zhang, Xu School of Mechanical Engineering Tongji University Shanghai200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai200092 China

Underground garages, indoor stadiums, or more commonly used seagoing ships, can be used as large multi-purpose spaces, which are suitable for the carriage of a wide range of cargoes, as well as evacuation of people at overseas. The indoor environment in a multi-purpose cabin usually varies, in terms of pollutant emissions, hazardous levels and the corresponding ventilation requirements. A possible solution, in addition to a single regular HVAC system, is to use multiple induced jet fans. However, to pre-determine a universal design of fans, e.g., numbers, locations, directions, angles and flowrates, etc., may not be practical. In this preliminary work, methods to design the auxiliary ventilation system were discussed. The heat sources are located in the four corners on the floor. CFD method is used to further study the effects of six regular and four irregular arrangements of a 2×2 array of fans on local heat dilution with or without natural ventilation (e.g., additional openings in the space). Heat exhaust efficiency is used to evaluate the effects of different arrangements of fans on local heat dilution. The results show that adjustable ventilation using induced fans would be useful to provide various airflow distribution for a large space and the dilution of the heat can be improved and the areas of high temperature inside the space can be reduced. Furthermore, the heat exhaust efficiency would be higher and the induced fans have a more significant effect, especially when additional natural ventilation is available. © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0

关键词： Efficiency

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Graphitic Carbon Nitride (g-C3N4): An Interface Enabler for Solid-State Lithium Metal Batteries

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Advanced Materials 2020年第9期59卷 3728-3733页

作者： Huang, Ying Chen, Bo Duan, Jian Yang, Fei Wang, Tengrui Wang, Zhengfeng Yang, Wenjuan Hu, Chenchen Luo, Wei Huang, Yunhui Institute of New Energy for Vehicles School of Materials Science and Engineering Tongji University Shanghai201804 China Key Laboratory of Performance Evolution and Control for Engineering Structures of the Ministry of Education Tongji University Shanghai200092 China

Solid-state Li metal batteries (SSLMBs) have attracted considerable interests due to their promising energy density as well as high safety. However, the realization of a well-matched Li metal/solid-state electrolyte (SSE) interface remains challenging. Herein, we report g-C3N4 as a new interface enabler. We discover that introducing g-C3N4 into Li metal can not only convert the Li metal/garnet-type SSE interface from point contact to intimate contact but also greatly enhance the capability to suppress the dendritic Li formation because of the greatly enhanced viscosity, decreased surface tension of molten Li, and the in situ formation of Li3N at the interface. Thus, the resulting Li-C3N4 | SSE | Li-C3N4 symmetric cell gives a significantly low interfacial resistance of 11 Ωcm2 and a high critical current density (CCD) of 1500 μAcm−2. In contrast, the same symmetric cell configuration with pristine Li metal electrodes has a much larger interfacial resistance (428 Ωcm2) and a much lower CCD (50 μAcm−2). © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

关键词： Lithium

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Experimental investigation on structural behavior of a stacked reinforced-concrete arch

Experimental investigation on structural behavior of a stack...

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fib Symposium 2019: Concrete - Innovations in Materials, Design and structures

作者： Zhang, Jiao-Long Zhao, Ji-Bin Liu, Xian Jiang, Shou-Chao Yang, Zhen-Hua Jiang, Hua-Cong College of Civil Engineering Tongji University Shanghai China Key Laboratory of Performance Evolution and Control for Engineering Structures Ministry of Education Tongji University Shanghai China State Key Laboratory for Disaster Reduction in Civil Engineering Tongji University Shanghai China

ISBN: (纸本)9782940643004

Arches are very efficient structures when subjected to distributed loads, because the latter are predominantly carried by compressive normal forces. This provides the motivation to construct arch vaults of large-span underground space. In this paper, a real-scale test of a stacked arch vault was carried out. The word "stacked" refers to a combination of the precast ribbed-arch shells, severing as permanent formworks, and the in-situ cast reinforced concrete. One end of the tested arch was clamped and the other was placed on a slide support. The latter allows for the test carried out in a displacement-load simultaneously controlled fashion. The test was organized in three phases, simulating the scenarios of installation of the permanent formwork, casting concrete in site, and of imposing loading on the stacked arch, respectively. The displacement, the temperature during the hardening of the in-situ casted concrete, stresses of the reinforcements, and the strains of concrete were monitored. The main conclusions are drawn as follows: Using precast ribbed-arch shells as permanent formwork clearly saved the timber and time in manufacture of the curved formwork. controlling the displacement of the supporting was the main issue, because it resulted in significant increase of deflection of the structure and, after the stacked arch was formed, considerable change of the internal forces. The latter could result in the cracking of concrete in the crown region. Euler-Bernoulli hypothesis was valid for the stacked arch by means of checking the strain distribution along the cross-sectional height. © Federation Internationale du Beton (fib) - International Federation for Structural Concrete, 2019.

关键词： Arches

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Experiment and Analysis of Thermal Conductivity of Marine Concrete with Different Composition 4

Experiment and Analysis of Thermal Conductivity of Marine Co...

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2018 4th International Conference on Energy Equipment Science and engineering, ICEESE 2018

作者： Zhang, Qingzhang Tian, Shuanzhu Li, Kangzong Li, Zhongyuan College of Civil Engineering and Architecture Henan University of Technology Zhengzhou Henan450001 China Key Laboratory of Performance Evolution and Control for Engineering Structures Tongji University Ministry of Education Shanghai200092 China

The thermal conductivity and porosity of marine concrete with different composition were measured by transient plane heat source method. The effects of aggregate volume fraction, sand ratio and water-cement ratio on thermal conductivity of marine concrete were investigated. Through the analysis of these factors and the comparison with other scholars, it is found that the thermal conductivity of marine concrete increases with the increase of aggregate volume fraction, decreases with the increase of sand ratio and water-cement ratio. © Published under licence by IOP Publishing Ltd.

关键词： Cements

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Why Energy-Efficient Behaviors are Delayed? Exploring the Moderating Role of Procrastination in Green Ticks Experiment Probing Household Refrigerator Upgrading

SSRN

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SSRN 2022年

作者： Shen, Meng Jagu, Dattakiran Lu, Yujie Ma, Xuran Center for Energy and Environmental Policy Research Beijing Institute of Technology Beijing100081 China School of Management and Economics Beijing Institute of Technology Beijing10081 China Sustainable Development Research Institute for Economy and Society of Beijing Beijing100081 China Lecce73100 Italy Department of Building Engineering College of Civil Engineering Tongji University Shanghai200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University Shanghai200092 China Shanghai Institute of Intelligent Science and Technology Tongji University Shanghai200092 China

Information and behavioral biases can affect consumers’ intertemporal decision on energy-efficient products investment. This study aims to discover the moderate effect of irrational procrastination, as a key behavioral bias, on consumers’ delayed decision in energy-efficient appliances upgrade and to explore possible intervention to address the delay caused by procrastination. In this regard, a survey-based field study was carried out among 153 households in Singapore with a structured questionnaire about their awareness of the green ticks, procrastinatory behavior, intention of delaying refrigerator upgrade, and demographic variables. The results show that green ticks alone led to negligible influence on energy-efficient appliance upgrade. Whereas in the presence of green ticks, consumers with lower levels of procrastination are more likely to avoid such delay in refrigerator upgrade, which can be explained by the lower hyperbolic discount rate. What’s more, the strategy of present the information about the cost of delaying purchase can mitigate the behavior deviation caused by procrastination. The findings provide quantitative implications for policymakers to speed up consumers’ upgrades on energy-efficient home appliances in Singapore. Adding the cost of delaying purchase on energy label, emphasizing the huge impact of procrastination on energy saving, and publicizing energy-efficient appliances in high-income groups are effectiveness interventions which can reduce delayed upgrade time. © 2022, The Authors. All rights reserved.

关键词： Refrigerators

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Application of heat pump combined two-stage desiccant wheel fresh air system of residential buildings in mixed climate zone 13

Application of heat pump combined two-stage desiccant wheel ...

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13th REHVA World Congress, CLIMA 2019

作者： Tian, Shaochen Su, Xing Zhang, Xu School of Mechanical Engineering Tongji University 1239 Siping Road Shanghai200092 China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji University 1239 Siping Road Shanghai200092 China

The building requires dehumidification for a long period of time in mixed climate zone of China. As a conventional method for dehumidification, vapor compression systems remove the water vapor by cooling the process air below dew point. This system consumes a lot of energy for reheating the air to meet the requirement of supply air temperature. A heat pump combined with two-stage desiccant wheel (TSDW&HP) is proposed as an air conditioning and dehumidification system in this study. The operation performance of proposed system applied in a hypothetical residence with 3 residents was investigated and simulated by using TRNSYS software. The operation modes of the system are discussed for different scenarios of season and outdoor air humidity ratio. In dehumidification season, fresh air deals with all of the latent load. In air conditioning season, fresh air deals with all of the moisture load with part of the cooling load. When evaporation temperature of HP is reduced and more moisture load is processed by evaporator in air conditioning season, there is a balance point between the performance of DWs and heat pump. The energy consumption of TSDW&HP fresh air system was compared with a conventional fresh air conditioner during dehumidification season and air conditioning season. It was found that the energy-saving potential of this system is 27.3% compared with conventional air conditioner. © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0

关键词： Air conditioning

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Investigation of influences of the strengthening timing of shield tunnels strengthened by steel plate – UHPC composite structure

Investigation of influences of the strengthening timing of s...

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fib Symposium 2019: Concrete - Innovations in Materials, Design and structures

作者： Liu, Xian Jiang, Zijie Yuan, Yong College of Civil Engineering Tongji University Shanghai China Key Laboratory of Performance Evolution and Control for Engineering Structures Ministry of Education Tongji University Shanghai China Institute for Mechanics of Materials and Structures Vienna University of Technology Vienna Austria

ISBN: (纸本)9782940643004

In present research, a full-scale test was conducted, in which the shield tunnel lining was strengthened initially, before it is subjected to loads. The loading scheme in this test is called firstly loading. From the full-scale test, the ultimate bearing capacity, the failure process, and the failure mode were obtained. A comparison of experimental results between the shield tunnel strengthened by SPUHPCCS strengthening technique under firstly loading and under secondly loading (the shield tunnel is strengthened when it reaches the ultimate state) was carried out, for the purpose of investigating the influences of the strengthening timing on the strengthening benefits. It shows that the strengthening timing does not have much influence on the ultimate bearing capacity. The ultimate bearing capacity of the strengthened structure under firstly loading is only 5.7% larger than that under secondly loading. However, it can significantly increase the structural stiffness and the ductility of the strengthened structure, by 520.6% and 106.8%, respectively. © Federation Internationale du Beton (fib) - International Federation for Structural Concrete, 2019.

关键词： Timing circuits

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