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Stresses due to an adhesion crack in T-shaped junction of two orthotropic plates

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Acta Mechanica Sinica 2012年第2期28卷 419-423页

作者： Dai-heng chen Department of Mechanical Engineering Tokyo University of Science 1-3 KagurazakaShinjuku-ku Tokyo 162-8601 Japan

The general solution of stresses is derived for a T-shaped junction of two thin plates with an adhesion crack. The plates are orthotropic. A shear force is applied on the crack surface. The analysis is based on the supposition that the stresses in each plate can be approximated by a plane stress condition. The results obtained are verified by numerical calculation of FEM.

关键词： Elasticity Crack Thin plate T-shaped Junc-tion Hilbert Problem

Flexural rigidity of honeycomb consisting of hexagonal cells

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Acta Mechanica Sinica 2011年第5期27卷 840-844页

作者： Dai-heng chen Department of Mechanical Engineering Tokyo University of Science1-3 Kagurazaka Shinjuku-kuTokyo 162-8601 Japan

In this study,the flexural rigidity of a honeycomb consisting of regular hexagonal cells is *** is found that the honeycomb bending can not be evaluated by using the equivalent elastic moduli obtained from the in-plane deformation because the moments acting on the inclined cell wall are different for in-plane deformation and bending *** on the fact that the inclined wall is twisted under the condition of the rotation angle in both connection edges being zero,a theoretical technique for calculating the flexural rigidity of honeycombs is proposed,and the validity of the present analysis is demonstrated by numerical results obtained by BFM.

关键词： Honeycomb · Flexural rigidity · Equivalent elastic modulus · Bending · Elasticity

Correlation of surface features with corrosion behaviors of interstitial free steel processed by temper rolling

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Journal of Materials Science & Technology 2020年第1期36卷 37-44页

作者： heng chen Zebang He Lin Lu Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing100083China State Key Laboratory of Metal Material for Marine Equipment and Application Anshan114000China

Temper rolling,as a final manufacturing procedure,brings the change of surface features and hence affects the corrosion behaviors of interstitial-free(IF)*** study investigates changes in residual stress,microstructure,and surface topography of IF steel using X-ray diffraction,electron backscatter diffraction,and optical interferometric *** the synthetic influence of surface features on the corrosion process of the steel was evaluated by damp heat tests and electrochemical *** showed that low tensile and compressive residual stresses are introduced to the surface of the IF *** grains had a grain orientation spread(GOS)value greater than 0.50 after temper ***,temper rolling caused a slight change in the surface profile of the IF *** compressive residual stress had an overwhelming role at the macroscopic level,in retarding the corrosion evolution process of IF steel,as well as in decreasing the average corrosion *** corrosion was more likely to initiate and propagate in matrices with a high GOS value,which played the determinant role at the microscopic ***,the depth of valley in the surface profile could affect the diffusion process involved in the electrode reactions,which was more likely to exert an extra influence on the corrosion rate of IF steel.

关键词： Temper rolling Surface feature Corrosion behavior Interstitial-free steel

Performance evaluation of an improved biomass-fired cogeneration system simultaneously using extraction steam, cooling water, and feedwater for heating

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Frontiers in Energy 2022年第2期16卷 321-335页

作者： Peiyuan PAN Yunyun WU heng chen Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation North China Electric Power UniversityBeijing 102206China

An advanced cogeneration system based on biomass direct combustion was developed and its feasibility was demonstrated. In place of the traditional single heat source (extraction steam), the extraction steam from the turbine, the cooling water from the plant condenser, and the low-pressure feedwater from the feedwater preheating system were collectively used for producing district heat in the new scheme. Hence, a remarkable energy-saving effect could be achieved, improving the overall efficiency of the cogeneration system. The thermodynamic and economic performance of the novel system was examined when taking a 35 MW biomass-fired cogeneration unit for case study. Once the biomass feed rate and net thermal production remain constant, an increment of 1.36 MW can be expected in the net electric production, because of the recommended upgrading. Consequently, the total system efficiency and effective electrical efficiency augmented by 1.23 and 1.50 percentage points. The inherent mechanism of performance enhancement was investigated from the energy and exergy aspects. The economic study indicates that the dynamic payback period of the retrofitting project is merely 1.20 years, with a net present value of 5796.0 k$. In conclusion, the proposed concept is validated to be advantageous and profitable.

关键词： biomass-fired cogeneration district heat production system absorption heat pump extraction steam cooling water low-pressure feedwater

Wavelet shrinkage estimators of Calderón-Zygmund operators with odd kernels

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Science China Mathematics 2014年第9期57卷 1983-1991页

作者： chen heng WU JiTao Department of Mathematics Beijing University of Aeronautics and Astronautics

Wavelet shrinkage is a strategy to obtain a nonlinear approximation to a given function f and is widely used in data compression,signal processing and statistics,*** Calder′on-Zygmund operators T,it is interesting to construct estimator of T f,based on wavelet shrinkage estimator of *** the help of a representation of operators on wavelets,due to Beylkin et al.,an estimator of T f is presented in this *** almost everywhere convergence and norm convergence of the proposed estimators are established.

关键词： wavelets shrinkage singular integral operator non-standard form maximal operator

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

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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

Photocatalytic performance and dispersion stability of nanodispersed TiO2 hydrosol in electrolyte solutions with different cations

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Journal of Environmental Sciences 2020年第2期32卷 59-71页

作者： Zixiao Wang Pan Feng heng chen Qingliang Yu Jiangsu Key Laboratory of Construction Materials School of Materials Science and EngineeringSoutheast UniversityNanjing 211189China Department of the Built Environment Eindhoven University of Technology5600 MB Eindhoventhe Netherlands School of Civil Engineering Wuhan UniversityWuhan 430072China State Key Laboratory of High Performance Civil Engineering Materials Nanjing 210008China

The existence of electrolytes in aquatic environment on the photocatalytic performance and coagulation of nanodispersed TiO2 hydrosol and the corresponding photocatalytic alteration were investigated by studying cations(Na^+, K^+, Ca^2+, Mg^2+, and Al^3+).The photocatalysis reactions of nano TiO2 with different dosages of electrolytes were measured by monitoring the degradation of Rhodamine B(Rh B) under ultraviolet A(UV-A) irradiation over *** results showed that the photocatalytic performance of TiO2 was improved by the presence of Al^3+, while the performance was impaired by the other tested *** negative influences of divalent ions on the photocatalytic performance of TiO2 were more significant than monovalent *** TiO2 sol dispersed stable at nano scale at low concentration of electrolyte( 0.1 mol/L) with larger increase or decrease of *** positive effects of Al^3+on the photodegradation rate of Rh B might relate to the strong hydrolytic action of Al^3+in aquatic *** photocatalytic processes of TiO2 in the presence of all ions followed the Langmuir-Hinshelwood model, and the reaction kinetic constant was increased with the decrease of pH caused by different *** work suggested a new perspective about the relationship between coagulation and photocatalytic performance of TiO2 hydrosols in electrolyte with hydrolysable cations, which demonstrated that TiO2 hydrosols may be suitable as photocatalysts in aquatic environments.

关键词： Photocatalytic oxidation Nano dispersed TiO2 hydrosol Aqueous inorganic cations Stability Photocatalytic kinetic

A coal-fired power plant integrated with biomass co-firing and CO_(2) capture for zero carbon emission

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Frontiers in Energy 2022年第2期16卷 307-320页

作者： Xiaojun XUE Yuting WANG heng chen Gang XU Beijing Key Laboratory of Emission Surveillance and Control for Thermal Power Generation North China Electric Power UniversityBeijing 102206China

A promising scheme for coal-fired power plants in which biomass co-firing and carbon dioxide capture technologies are adopted and the low-temperature waste heat from the CO_(2) capture process is recycled to heat the condensed water to achieve zero carbon emission is proposed in this *** on a 660 MW supercritical coal-fired power plant,the thermal performance,emission performance,and economic performance of the proposed scheme are *** addition,a sensitivity analysis is conducted to show the effects of several key parameters on the performance of the proposed *** results show that when the biomass mass mixing ratio is 15.40%and the CO_(2) capture rate is 90%,the CO_(2) emission of the coal-fired power plant can reach zero,indicating that the technical route proposed in this paper can indeed achieve zero carbon emission in coal-fired power *** net thermal efficiency decreases by 10.31%,due to the huge energy consumption of the CO_(2) capture ***,the cost of electricity(COE)and the cost of CO_(2) avoided(COA)of the proposed system are 80.37/MWhand41.63/tCO_(2),*** sensitivity analysis demonstrates that with the energy consumption of the reboiler decreasing from 3.22 GJ/tCO_(2) to 2.40 GJ/tCO_(2),the efficiency penalty is reduced to 8.67%.This paper may provide reference for promoting the early realization of carbon neutrality in the power generation industry.

关键词： coal-fired power plant biomass co-firing CO_(2)capture zero carbon emission performance evaluation

Dynamically tunable multifunctional QED platform

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Science China(Physics,Mechanics & Astronomy) 2019年第7期62卷 82-88页

作者： Li-heng chen GengYan chen RenMing Liu Xue-Hua Wang State Key Laboratory of Optoelectronic Materials and Technologies School of Physics Sun Yat-sen University School of Optoelectronic Engineering Guangdong Polytechnic Normal University

Solid-state quantum electrodynamics(QED) not only demonstrates basic principles of quantum physics, but also provides key support to future quantum technologies. However, the non-modifiability of the fabricated solid-state QED systems limits their flexibility and versatility in manipulating light-matter interaction, and severely hinders their practical applications. Here, we put forward an approach of multi-dimensionally manipulating light-matter interaction to realize a dynamically tunable multifunctional QED platform by combining the local light-induced refractive index modulation(LRIM) and strong dispersion characteristic of the photonic crystal(PC) waveguide. We demonstrate three significant functions of the platform as examples:switch control between weak and strong couplings on demand, distant quantum entanglement, and a directional single photon source with high brightness and efficiency. These functions are strongly robust against positioning error of the quantum emitter,and can be facilely realized only by local LRIM on one PC waveguide. Our work paves a new way for the realization of multifunctional quantum devices.

关键词： cavity quantum electrodynamics quantum entanglement single photon source photonic crystal