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Simulation of roof snow loads based on a multi-layer snowmelt model:Impact of building heat transfer

Building Simulation 2024年第6期17卷 907-932页

作者： Xuanyi Zhou Heng Chen Yue Wu Tiange Zhang State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai200092China

To investigate the impact of building heat transfer on roof snow loads,roof snow loads and snow load thermal coefficients from 61 Chinese sites over a period of 50 years are simulated based on basic meteorological data such as temperature,humidity,wind speed,and precipitation,and a multi-layer snowmelt model considering the building heat ***,the accuracy of the multi-layer snowmelt model is validated using the data of observed ground snow load and roof snow melting *** relationship between meteorological conditions,snow cover characteristics,and thermal coefficients of snow loads in three representative sites is then ***,the characteristics of thermal coefficients in each zone are analyzed by combining them with the statistical results of meteorological data from 1960 to 2010,and the equations of thermal coefficients in different zones on indoor temperatures and roof heat transfer coefficients are fitted ***,the equations in this paper are compared with the thermal coefficients in the main snow load *** results indicate that the snowmelt model using basic meteorological data can effectively provide samples of roof snow *** the cold zone where the snow cover lasts for a long time and does not melt easily,the thermal coefficients of the snow loads on the heating buildings are lower than those in the warm zone due to the long-term influence of the heat from inside the *** coefficients are negatively correlated with indoor temperatures and roof heat transfer *** the indoor temperature is too low or the roof insulation is good,the roof snow load may exceed the ground snow *** thermal coefficients for heated buildings in the main snow load codes are more conservative than those calculated in this paper,and the thermal coefficients for buildings with lower indoor temperatures tend to be smaller.

关键词： snowmelt model roof snow load building heat transfer thermal coefficient load code

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Temperature-insensitive and high-precision frequency transfer based on fabricated in-house 1.05 km hollow-core anti-resonant fiber

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Chinese Optics Letters 2024年第10期22卷 25-32页

作者： Yundong Hao Zefeng Li Sensen Meng Bo Liu Zhende Zhai Lei Zheng Ye Wang Yange Liu Institute of Modern Optics Nankai UniversityTianjin 300350China Shenzhen Sublime Photonics Co. Ltd.Shenzhen 518000China

We have prepared kilometer-scale low-loss hollow-core nested anti-resonant nodeless fibers by improving their structural design,which reduces the difficulty of fabricating low-loss hollow-core fibers over long *** lowest loss is 2.7 d B/km at 1506 nm,and this loss is less than 5 d B/km at 1417–1620 ***-precision frequency transfer is achieved using the fabricated 1050 m hollow-core fiber by locking the repetition frequency of the optical frequency comb to a rubidium atomic *** frequency stability is 1.67×10^(-12)/s and 5.66×10^(-14)/1000 s when the temperature is changed,and no phase compensation device is *** is an order of magnitude lower compared to that of the conventional single-mode fiber.

关键词： hollow-core anti-resonant fiber thermal coefficient delay frequency transfer femtosecond comb

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Identification and analysis based on genetic algorithm for proton exchange membrane fuel cell stack

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Journal of Central South University of Technology 2006年第4期13卷 428-431页

作者：李曦曹广益朱新坚卫东 Depart ment of Control Science and Engineering Huazhong University of Science and Technolgy Depart ment of Automation Shanghai Jiaotong University

The temperature of proton exchange membrane fuel cell stack and the stoichiometric oxygen in cathode have relationship with the performance and life span of fuel cells closely. The thermal coefficients were taken as important factors affecting the temperature distribution of fuel cells and components. According to the experimental analysis, when the stoichiometric oxygen in cathode is greater than or equal to 1.8, the stack voltage loss is the least. A novel genetic algorithm was developed to identify and optimize the variables in dynamic thermal model of proton exchange membrane fuel cell stack, making the outputs of temperature model approximate to the actual temperature, and ensuring that the maximal error is less than 1 ℃. At the same time, the optimum region of stoichiometric oxygen is obtained, which is in the range of 1.8-2.2 and accords with the experimental analysis results. The simulation and experimental results show the effectiveness of the proposed algorithm.

关键词： proton exchange membrane fuel cell genetic algorithm temperature thermal coefficient stoichiometric oxygen

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Research on High-temperature thermal Effect Laws and Thermodynamic Characteristics of Salt Rock

Research on High-temperature Thermal Effect Laws and Thermod...

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2012年海峡两岸破坏科学/材料试验学术会议

作者： JIANG Kai-le LI Yun-peng ZHENG Ya-li ZHANG Hua-bin College of Mechanical and Transportation Engineering China University of Petroleum Research Institute of Petroleum Exploration & Development

Accumulation and explosion of thermal energy have a potential influence on mechanical parameters and strength of salt rock in the process of gas injection and *** this study,thermal properties at high temperature were determined through experimental research. The relation between stress and strain,mechanical parameters,and the law of thermal effects were investigated through nonlinear thermodynamics *** researches shown that strength measured by conventional triaxial compression test under different confining pressure raised with the increase of temperature,the strength raised with the increase of confining pressure at the same *** addition,the strength are affected by physical parameters of salt rock.A nonlinear relation was appeared between thermal coefficient and *** in this paper have a reference value to deeply research of mechanical properties of salt rock and engineering project of salt-cavern gas storage.

关键词： Salt Rock High Temperature thermal Effect thermal coefficient Triaxial Compression Tes

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