检索结果-南通市图书馆

Recent progress in modelling and simulation technologies of energy efficiency and environmental quality in the built environment

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Building Simulation 2022年第7期15卷 1175-1176页

作者： Wenhui Ji Yanping Yuan Liangliang Sun Xudong Zhao School of Mechanical Engineering Southwest Jiaotong UniversityNo.111North Section 1Second Ring RoadChengdu 610031China University of Hull School Engineering and Computer ScienceKingston Upon Hull HU67RXN HumbersideUK

The International Conference for Global Chinese Academia on Energy and Built Environment(ICCEBE)is a premier international event covering a broad range of topics on clean energy utilization,energy efficiency and environmental quality in the built environment.The conference aims to provide a forum to share cutting-edge achievements in the built environment,and to promote academic collaboration and cooperation among worldwide Chinese scholars.

关键词： energy modelling collaboration

Numerical investigation on temperature–humidity field under mechanical ventilation in the construction period of hot-humid tunnel along the Sichuan–Tibet Railway

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Underground Space 2023年第1期8卷 123-143页

作者： Kaiming Zhao Yanping Yuan Fujian Jiang Xiaoling Cao School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

High temperature–humidity environment is one of the severe challenges in constructing Sichuan–Tibet railway tunnels.For enhancing construction efficiency and guaranteeing tunnel worker safety,addressing the high temperature–humidity environment has irreplaceable significance.This study innovatively investigated the distribution law and evolution process of the thermal–humidity coupling field dur-ing tunnel construction.Besides,the corresponding ventilation measures were proposed based on the evaluation heat index(HI).If the initial temperature of the surrounding rock is constant,the distance between the ventilation duct outlet and the tunnel working face should not be greater than 30 m.Otherwise,the cooling performance of ventilation will be significantly weakened;If this temperature ranges in 65–85℃,the recommended ventilation velocity is 10–25 m/s,and the ventilation distance should not exceed 20 m.The con-clusions in this study are beneficial to better understand the high temperature–humidity environment in tunnel construction and can be a guideline for practical engineering application.

关键词： CFD simulation Heat and mass transfer Tunnel environment Tunnel ventilation

Synthesis and thermal properties of nanoencapsulation of paraffin as phase change material for latent heat thermal energy storage

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

能源与人工环境(英文)

能源与人工环境(英文) 2020年第4期1卷 410-416页

作者： Nan Zhang Yanping Yuan School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

In this work,a series of nanoencapsulated phase change materials(NanoPCMs)with paraffin wax(PW)as core and melamine-formaldehyde(MF)as shell were synthesized by the in-situ polymerization method.The morphol-ogy,chemical structure and thermal properties of prepared NanoPCMs were characterized by scanning electron microscope,Fourier transform infrared,differential scanning calorimetry and thermogravimertic analyzer.The results show that the PW is successfully encapsulated in the MF without chemical interaction,and the NanoPCMs present regular spherical shape with the average diameter of 260-450 nm.The encapsulation efficiency of the NanoPCMs increases with the augment of the supplied amount of core material.The maximum encapsulation efficiency of the NanoPCMs can reach up to approximately 75%.The NanoPCMs can maintain excellent thermal reliability and stability after 2000 thermal cycling.The prepared NanoPCMs can be well applied in the latent heat thermal energy storage and thermal management systems due to their remarkable encapsulation efficiency and thermal properties enable them to.

关键词： Nanoencapsulted PCMs Encapsulation efficiency Thermal properties Thermal energy storage

Lipid control in adult Chinese patients with type 2 diabetes:a retrospective analysis of time trends and geographic regional differences

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Medical Journal 2022年第3期135卷 356-358页

作者： Yanping Yuan Xianghai Zhou Juming Lu Xiaohui Guo Linong Ji Department of Endocrinology Peking University People's HospitalBeijing 100044China Department of Endocrinology Chinese PLA General HospitalBeijing 100853China Department of Endocrinology First Hospital of Peking UniversityBeijing 100034China

To the Editor:Patients with type 2 diabetes have a higher risk of cardiovascular diseases(CVD),relative to people without diabetes.Patients with diabetes always exhibit lipid abnormalities.Rapid economic development and accelerated urbanization have also led to lifestyle changes that may have an influence on the lipid parameters of Chinese patients with diabetes.Given the significant differences in socioeconomic status in China,geographical variations were also observed in the prevalence,awareness,treatment,and control of dyslipidemia among individuals who were≥45 years old in the general Chinese population.[1]There is a lack of large-scale studies regarding time trends and geographical variations in lipid concentrations and lipid control among Chinese adults with type 2 diabetes.Therefore,we conducted a study on time trends and geographical variations in lipid concentrations and lipid control in this population using the China National HbA1c Surveillance System(CNHSS)database of adult Chinese outpatients with type 2 diabetes during 2009 to 2013.The Ethics Committee of the Chinese People Liberation Army General Hospital approved the study protocol.Informed consent was obtained from all the patients before they were interviewed and data collected.

关键词： patients diabetes Lipid

Pyrolysis Empirical Modeling of Polyester Glass Fiber Reinforced Plastics Using Sestak-Berggren Model Method

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第2期33卷 725-738页

作者： NAN Wei JI Wenhui yuan yanping yuan Zhongyuan SUN Yong School of Mechanical Engineering Southwest Jiaotong UniversityChengdu610031China CRRC Changchun Railway Vehicles Co. LtdChangchun130062China

Polyester Glass Fiber Reinforced Plastic(Polyester GFRP),a thermosetting plastic comprised of glass fiber and polyester polymer compounds,is extensively utilized in high-speed trains.Unraveling its pyrolysis mechanism is crucial as it significantly influences the combustion characteristics and fire safety aspects.Currently,kinetic research on polyester GFRP primarily focuses on employing the Coats-Redfern method to derive a theoretical kinetic model.However,the pyrolysis process of polyester GFRP is complex and the aforementioned theoretical model fails to accurately describe the pyrolysis mechanism.Therefore,this study seeks to utilize the Sestak and Berggren(SB) model as a methodological approach to reveal the complex reaction mechanism during the pyrolysis process.Based on thermogravimetric analysis,the entire pyrolysis process of polyester GFRP is divided into two primary stages.Furthermore,model-free methods are employed to ascertain the activation energy and pre-exponential factor.The results show that the fitted empirical models of the two main pyrolysis stages are f(α)=(1-α)^(1.47)[-ln(1-α)]^(1.50) and f(α)=(1-α)^(1.77)[-ln(1-α)]^(1.72),respectively.The predicted results are in good agreement with experimental data under different heating rates,which indicates that the empirical model can sufficiently describe the pyrolysis process of polyester GFRP.

关键词： polyester GFRP model-fitting methods empirical models pyrolysis

Numerical simulation of smoke stratification in tunnel fires under longitudinal velocities

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Underground Space 2021年第2期6卷 163-172页

作者： Yuhao Guo Zhongyuan yuan Yanping Yuan Xiaoling Cao Peng Zhao School of Mechanical Engineering Southwest Jiaotong University111Second Ring RoadChengdu CitySichuan Province 610031PR China

Use of the longitudinal critical velocity in tunnel fires may destroy the stratification of smoke downstream,which is not conducive to the evacuation of downstream tunnel users.Reducing the longitudinal velocity can maintain stratification,but the appropriate longitudinal velocity range is unknown.Stratification of smoke under the longitudinal velocity is studied using Fire Dynamics Simulator(FDS).The aims of this paper are to explore the relationship between the longitudinal velocity and smoke stratification and to obtain a proper velocity range that can maintain clear downstream stratification.Based on Newman's theory,the"stratification velocity"is proposed,which is the maximum velocity that maintains downstream smoke stratification.A good correspondence between the average Froude number within 200 m downstream and the longitudinal velocity and heat release rate(HRR)is found.The correlation between the temperature stratification and Froude number is obtained.Fr=0.49 can be used to distinguish whether the stratification is clear.The relationship between the critical velocity and the stratification velocity is also discussed.

关键词： Tunnel fire Longitudinal ventilation Smoke stratification

High temperature oxidation properties of Al-Cu-Si alloys for latent heat energy storage

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy and Built Environment

Energy and Built Environment 2023年第3期4卷 308-314页

作者： Junwen Zhao Yan Shi Yanping Yuan Xingmin Huang Jing Han School of Materials Science and Engineering Key Lab of Advanced Technologies of Materials(Ministry of Education)Southwest Jiaotong UniversityChengdu 610031China School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

The effect of Cu content on the high temperature oxidation properties of the phase change material(PCM)Al-Cu-Si alloys was studied.The oxidation kinetics curves at 600◦C were achieved for Al-Cu-Si alloys with 35-55%Cu,which all follow the cubic law.With an increase in the Cu content from 35 to 55%,the weight gain decreases from 5.75 to 3×10^(−4) g/cm^(2) after 96 h isothermal oxidation.The oxidation rate also decreases with Cu content,the maximum and minimum rates are 1.52 and 0.32×10^(−5) g/cm^(2)•h,a nearly 4 times difference.Oxidation does not change the phase composition of Al-Cu-Si alloys,but coarsens the microstructure.The latent heat and the starting temperature of phase change after 96 h oxidation at 600◦C have variations of less than 10%and 6◦C,respectively,indicating that the Al-Cu-Si alloys have good thermal stability after high temperature oxidation.

关键词： Al-Cu-Si alloy PCMs Oxidation properties Thermal stability

Elastic energy storage technology using spiral spring devices and its applications:A review

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy and Built Environment

Energy and Built Environment 2023年第6期4卷 669-679页

作者： Shiwei Guo Li Yang Yanping Yuan Zutao Zhang Xiaoling Cao School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

Harvesting and storing energy is a key problem in some applications.Elastic energy storage technology has the advantages of wide-sources,simple structural principle,renewability,high effectiveness and environmental-friendliness.This paper elaborates the operational principles and technical properties and summarizes the appli-cability of elastic energy storage technology with spiral springs.Elastic energy storage using spiral spring can realize the balance between energy supply and demand in some applications.Continuous input-spontaneous out-put working style can provide simple energy sources for short-time energy supply,and provide strong moment impact and rapid start,or realize the energy conservation for reciprocating movement.Uniform output working style can realize energy output with uniform speed for timekeeping and load-driving.Random input working style can harvest and store random mechanical energy or convert small torque into a large moment to drive external loads.Finally,this paper proposes new researches and developments of elastic energy storage technology on new materials and structures,mechanical properties and structural dynamics analyses,design and control for new functions.

关键词： Mechanical energy storage Elastic energy storage Spiral spring system Energy input/output characteristics Implementation mechanism

Wall-Attached Night Ventilation Combined with Phase Change Material Wallboard in Hot Summer:An Experimental Study on the Thermal Performance

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2022年第2期31卷 318-331页

作者： JI Wenhui yuan yanping LI Yajun YU Min School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China

Night ventilation is regarded as a promising cooling strategy by storing night cooling in the thermal mass of the building.However,night ventilation performance in hot summer is restricted by the climatic limits.In this paper,we propose a new solution as the integration of wall-attached night ventilation(WANV)and phase change material wallboard(PCMW).The principle of the proposed system is to utilize the wall-attached jet ventilation to achieve forced convection and to adopt latent energy storage of PCMW to enlarge the energy storage density capabilities,and the coupling method is expected to improve the night ventilation performance.Comparative experiments were conducted to evaluate the thermal performance of the hybrid system by evaluating indoor temperature history,thermal comfort time and cooling efficiency.Due to the high thermal energy storage density capability of PCMW,it was found that the presence of PCMW has a negative influence on night cooling efficiency but still has a positive influence on the overall cooling effect.The proposed WANV combined with the PCMW system significantly increased the temperature decrease of room air and west wall inside surface during one hour's night ventilation by 94.97%and 67.74%,respectively,and reached an extension of 38.42%of indoor thermal comfort time.The results highlight the potential of WANV integration of PCMW to improve the thermal performance of night ventilation.

关键词： night ventilation wall-attached jet ventilation phase change material wallboard thermal performance