In this paper,the node based smoothed-strain Abaqus user element(UEL)in the framework of finite element method is introduced.The basic idea behind of the node based smoothed finite element(NSFEM)is that finite element...In this paper,the node based smoothed-strain Abaqus user element(UEL)in the framework of finite element method is introduced.The basic idea behind of the node based smoothed finite element(NSFEM)is that finite element cells are divided into subcells and subcells construct the smoothing domain associated with each node of a finite element cell[Liu,Dai and Nguyen-Thoi(2007)].Therefore,the numerical integration is globally performed over smoothing domains.It is demonstrated that the proposed UEL retains all the advantages of the NSFEM,i.e.,upper bound solution,overly soft stiffness and free from locking in compressible and nearly-incompressible media.In this work,the constant strain triangular(CST)elements are used to construct node based smoothing domains,since any complex two dimensional domains can be discretized using CST elements.This additional challenge is successfully addressed in this paper.The efficacy and robustness of the proposed work is obtained by several benchmark problems in both linear and nonlinear elasticity.The developed UEL and the associated files can be downloaded from https://github.com/nsundar/NSFEM.展开更多
In the metropolises,it is unlikely to use merely solar and wind energy to pursue zero carbon building design.However,it would become possible if biofuel-driven trigeneration systems(BDTS)are adopted.It is thus essenti...In the metropolises,it is unlikely to use merely solar and wind energy to pursue zero carbon building design.However,it would become possible if biofuel-driven trigeneration systems(BDTS)are adopted.It is thus essential to assess the application opportunity of BDTS in a holistic way.In this study,BDTS offered definite primary energy saving of up to 15%and carbon emissions reduction of at least 86%in different types of non-residential buildings as compared to the conventional systems.With 24/7 operation for the hotel and hospital buildings,the corresponding BDTS could even achieve zero carbon emissions.All the BDTS primed with compression-ignition internal combustion engine were not economically viable even in running cost due to the high local biodiesel price level.The BDTS primed with spark-ignition engine and fueled by biogas,however,would have economic merit when carbon price was considered for the conventional systems that fully utilize fossil fuels.Adoption of carbon tax and social cost could have the payback ceilings of 8 years and 2 years respectively for most of building types.Consequently,the results could reflect the application potential of BDTS for non-residential buildings,leading the pathway to carbon neutrality for sustainable sub-tropical cities.展开更多
The precise building performance assessment of residential housings in subtropical regions is usually more difficult than that for the commercial premises due to the much more complicated behavior of the occupants wit...The precise building performance assessment of residential housings in subtropical regions is usually more difficult than that for the commercial premises due to the much more complicated behavior of the occupants with regard to the change in indoor temperature.The conventional use of a fixed schedule for window opening,clothing insulation and cooling equipment operation cannot reflect the real situation when the occupants respond to the change in thermal comfort,thus affecting the appropriateness of the assessment results.To rectify the situation,a new modeling strategy in which the modification of the various operation schedules was based on the calculated thermal comfort(TC),was developed in this study.With this new TC-based strategy,the realistic building performances under different cooling provision scenarios applied to a high-rise residential building under the near extreme weather conditions were investigated and compared.It was found that sole provision of ventilation fans could not meet the zone thermal comfort by over 68%of the time,and air-conditioning was essential.The optimal use of ventilation fans for cooling could only help reduce the total cooling energy demand by less than 12%at best which could only be realistically evaluated by adopting the present strategy.Parametric studies were conducted which revealed that some design factors could offer opportunities for reducing the total cooling energy under the near extreme weather conditions.展开更多
文摘In this paper,the node based smoothed-strain Abaqus user element(UEL)in the framework of finite element method is introduced.The basic idea behind of the node based smoothed finite element(NSFEM)is that finite element cells are divided into subcells and subcells construct the smoothing domain associated with each node of a finite element cell[Liu,Dai and Nguyen-Thoi(2007)].Therefore,the numerical integration is globally performed over smoothing domains.It is demonstrated that the proposed UEL retains all the advantages of the NSFEM,i.e.,upper bound solution,overly soft stiffness and free from locking in compressible and nearly-incompressible media.In this work,the constant strain triangular(CST)elements are used to construct node based smoothing domains,since any complex two dimensional domains can be discretized using CST elements.This additional challenge is successfully addressed in this paper.The efficacy and robustness of the proposed work is obtained by several benchmark problems in both linear and nonlinear elasticity.The developed UEL and the associated files can be downloaded from https://github.com/nsundar/NSFEM.
基金The work described in this paper was fully supported by a grant from City University of Hong Kong(Strategic Research Grant,Project No.7005033).
文摘In the metropolises,it is unlikely to use merely solar and wind energy to pursue zero carbon building design.However,it would become possible if biofuel-driven trigeneration systems(BDTS)are adopted.It is thus essential to assess the application opportunity of BDTS in a holistic way.In this study,BDTS offered definite primary energy saving of up to 15%and carbon emissions reduction of at least 86%in different types of non-residential buildings as compared to the conventional systems.With 24/7 operation for the hotel and hospital buildings,the corresponding BDTS could even achieve zero carbon emissions.All the BDTS primed with compression-ignition internal combustion engine were not economically viable even in running cost due to the high local biodiesel price level.The BDTS primed with spark-ignition engine and fueled by biogas,however,would have economic merit when carbon price was considered for the conventional systems that fully utilize fossil fuels.Adoption of carbon tax and social cost could have the payback ceilings of 8 years and 2 years respectively for most of building types.Consequently,the results could reflect the application potential of BDTS for non-residential buildings,leading the pathway to carbon neutrality for sustainable sub-tropical cities.
基金The work described in this paper was supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region,China(No.CU R4046-18F).
文摘The precise building performance assessment of residential housings in subtropical regions is usually more difficult than that for the commercial premises due to the much more complicated behavior of the occupants with regard to the change in indoor temperature.The conventional use of a fixed schedule for window opening,clothing insulation and cooling equipment operation cannot reflect the real situation when the occupants respond to the change in thermal comfort,thus affecting the appropriateness of the assessment results.To rectify the situation,a new modeling strategy in which the modification of the various operation schedules was based on the calculated thermal comfort(TC),was developed in this study.With this new TC-based strategy,the realistic building performances under different cooling provision scenarios applied to a high-rise residential building under the near extreme weather conditions were investigated and compared.It was found that sole provision of ventilation fans could not meet the zone thermal comfort by over 68%of the time,and air-conditioning was essential.The optimal use of ventilation fans for cooling could only help reduce the total cooling energy demand by less than 12%at best which could only be realistically evaluated by adopting the present strategy.Parametric studies were conducted which revealed that some design factors could offer opportunities for reducing the total cooling energy under the near extreme weather conditions.
