This paper aims to evaluate the feasibility of pressure-dependent models in the design of ship piping systems.For this purpose,a complex ship piping system is designed to operate in firefighting and bilge services thr...This paper aims to evaluate the feasibility of pressure-dependent models in the design of ship piping systems.For this purpose,a complex ship piping system is designed to operate in firefighting and bilge services through jet pumps.The system is solved as pressure-dependent model by the piping system analysis software EPANET and by a mathematical approach involving a piping network model.This results in a functional system that guarantees the recommendable ranges of hydraulic state variables(flow and pressure)and compliance with the rules of ship classification societies.Through this research,the suitability and viability of pressure-dependent models in the simulation of a ship piping system are proven.展开更多
We address the flow of incompressible fluid with a pressure-dependent viscosity through a pipe with helical shape. The viscosity-pressure relation is defined by the Barus law. The thickness of the pipe and the helix s...We address the flow of incompressible fluid with a pressure-dependent viscosity through a pipe with helical shape. The viscosity-pressure relation is defined by the Barus law. The thickness of the pipe and the helix step are assumed to be of the same order and considered as the small parameter. After transforming the starting problem, we compute the asymptotic solution using curvilinear coordinates and standard perturbation technique. The solution is provided in the explicit form clearly showing the influence of viscosity-pressure dependence and pipe＇s geometry on the effective flow.展开更多
The press-pack power module with multi-chip layout has drawn increasing attention from industry and academia with its thermal analysis becoming an essential issue.However,the pressure-dependent thermal variables,such ...The press-pack power module with multi-chip layout has drawn increasing attention from industry and academia with its thermal analysis becoming an essential issue.However,the pressure-dependent thermal variables,such as thermal contact resistance and thermal coupling resistance,are often neglected.In this paper,a pressure-dependent thermal network model is developed to characterize the thermal performance and mechanical status of press-pack power modules.By including the thermal contact resistance and thermal coupling resistance as the function of pressure,the proposed model ensures a more precise thermo-mechanical evaluation inside the press-pack power module.The influence of pressure on self-heating effects and thermal coupling effects of power modules is studied using the knowledge of elastic mechanics.A press-pack prototype with variable pressure loads is assembled.Then,thermal experiments under different pressures on chips are conducted and the pressure-variable temperature responses of the thermal network are measured.Consequently,the feasibility of the proposed thermal network model is validated.A cost-effective prognostic method on the mechanical status of press-pack power module is also achieved.展开更多
Spinal cord injury presents a significant challenge in regenerative medicine due to the complex and deli-cate nature of neural tissue repair.This study aims to design a conductive hydrogel embedded with magnetic MgFe_...Spinal cord injury presents a significant challenge in regenerative medicine due to the complex and deli-cate nature of neural tissue repair.This study aims to design a conductive hydrogel embedded with magnetic MgFe_(2)O_(4) nanoparticles to establish a bioelectrically active and spatially stable microenvironment that promotes spinal cord regeneration through computational analysis(BIOVIA Materials Studio).Hydrogels,known for their biocompatibility and extracellular matrix-mimicking properties,support essential cellular behaviors such as adhesion,proliferation,and migration.The integration of MgFe_(2)O_(4) nanoparticles imparts both electrical conductivity and magnetic responsiveness,enabling controlled transmission of electrical signals that are crucial for guiding cellular processes like differentiation and directed migration.Furthermore,the hydrogel acts as a delivery medium,facilitating the adsorption of MgFe_(2)O_(4) nanoparticles onto spinal tissue through strong Van der Waals and intramolecular interactions.The computational simulations revealed a robust adsorption profile,with a binding distance of 20.180Åand a cumulative adsorption energy of 2740.42 kcal/mol,indicating stable nanoparticle-tissue interactions.Pressure-dependent sorption analysis further demonstrated that reduced pressure conditions enhance adsorption strength,promoting tighter material-tissue integration.The adverse Van der Waals energy and increased intramolecular energy observed under these conditions underscore the importance of optimized adsorption settings for functional tissue interface formation.Altogether,the conductive hydrogel-MgFe_(2)O_(4) composite system offers a promising therapeutic platform by combining structural support,electrical stimulation,and magnetic guidance,thereby enhancing cell-material interactions and fostering an environment conducive to spinal cord tissue repair.展开更多
A series of linear stability analysis is carried out on the onset of thermal convection in the presence of spatial variations of viscosity, thermal conductivity and expansivity. We consider the temporal evolution of a...A series of linear stability analysis is carried out on the onset of thermal convection in the presence of spatial variations of viscosity, thermal conductivity and expansivity. We consider the temporal evolution of an infinitesimal perturbation superimposed to a static （motionless） and con- ductive state in a basally-heated planar layer. From the changes in flow patterns with increasing the amplitudes of temperature dependence of viscosity, we identified the transition into the ＂stagnant-lid＂ （ST） regime, where the convection occurs only beneath a thick and stagnant-lid of cold fluid at the top surface. Detailed analysis showed a significant increase of the aspect ratio of convection cells in ST regime induced by the spatial variations in thermal conductivity and/or expansivity： the horizon- tal length scale of ST convection can be enlarged by up to 50% with 10 times increase of thermal conductivity with depth. We further developed an analytical model of ST convection which success- fully reproduced the mechanism of increasing horizontal length scale of ST regime convection cells for given spatial variations in physical properties. Our findings may highlight the essential roles of the spatial variation of thermal conductivity on the convection patterns in the mantle.展开更多
Chemical looping reforming of methane is a novel and effective approach to convert methane to syngas,in which oxygen transfer is achieved by a redox material.Although lots of efforts have been made to develop high-per...Chemical looping reforming of methane is a novel and effective approach to convert methane to syngas,in which oxygen transfer is achieved by a redox material.Although lots of efforts have been made to develop high-performance redox materials,a few studies have focused on the redox kinetics.In this work,the kinetics of SrFeO_(3−δ)–CaO∙MnO nanocomposite reduction by methane was investigated both on a thermo-gravimetric analyzer and in a packed-bed microreactor.During the methane reduction,combustion occurs before the partial oxidation and there exists a transition between them.The weight loss due to combustion increases,but the transition region becomes less inconspicuous as the reduction temperature increased.The weight loss associated with the partial oxidation is much larger than that with combustion.The rate of weight loss related to the partial oxidation is well fitted by the Avrami–Erofeyev equation with n=3(A3 model)with an activation energy of 59.8 kJ∙mol^(‒1).The rate law for the partial oxidation includes a solid conversion term whose expression is given by the A3 model and a methane pressure-dependent term represented by a power law.The partial oxidation is half order with respect to methane pressure.The proposed rate law could well predict the reduction kinetics;thus,it may be used to design and/or analyze a chemical looping reforming reactor.展开更多
文摘This paper aims to evaluate the feasibility of pressure-dependent models in the design of ship piping systems.For this purpose,a complex ship piping system is designed to operate in firefighting and bilge services through jet pumps.The system is solved as pressure-dependent model by the piping system analysis software EPANET and by a mathematical approach involving a piping network model.This results in a functional system that guarantees the recommendable ranges of hydraulic state variables(flow and pressure)and compliance with the rules of ship classification societies.Through this research,the suitability and viability of pressure-dependent models in the simulation of a ship piping system are proven.
基金supported by the Croatian Science Foundation(scientific project 3955:Mathematical modeling and numerical simulations of processes in thin or porous domains)
文摘We address the flow of incompressible fluid with a pressure-dependent viscosity through a pipe with helical shape. The viscosity-pressure relation is defined by the Barus law. The thickness of the pipe and the helix step are assumed to be of the same order and considered as the small parameter. After transforming the starting problem, we compute the asymptotic solution using curvilinear coordinates and standard perturbation technique. The solution is provided in the explicit form clearly showing the influence of viscosity-pressure dependence and pipe＇s geometry on the effective flow.
基金supported by the National Natural Science Foundation of China(5187719252107211)the Zhejiang Provincial Natural Science Foundation of China(LQ21E070006).
文摘The press-pack power module with multi-chip layout has drawn increasing attention from industry and academia with its thermal analysis becoming an essential issue.However,the pressure-dependent thermal variables,such as thermal contact resistance and thermal coupling resistance,are often neglected.In this paper,a pressure-dependent thermal network model is developed to characterize the thermal performance and mechanical status of press-pack power modules.By including the thermal contact resistance and thermal coupling resistance as the function of pressure,the proposed model ensures a more precise thermo-mechanical evaluation inside the press-pack power module.The influence of pressure on self-heating effects and thermal coupling effects of power modules is studied using the knowledge of elastic mechanics.A press-pack prototype with variable pressure loads is assembled.Then,thermal experiments under different pressures on chips are conducted and the pressure-variable temperature responses of the thermal network are measured.Consequently,the feasibility of the proposed thermal network model is validated.A cost-effective prognostic method on the mechanical status of press-pack power module is also achieved.
基金the“Young Talent Research Grant”:(600-RMC/YTR/5/3(004/2022)Universiti Teknologi Mara(UiTM)for providing the financial support.
文摘Spinal cord injury presents a significant challenge in regenerative medicine due to the complex and deli-cate nature of neural tissue repair.This study aims to design a conductive hydrogel embedded with magnetic MgFe_(2)O_(4) nanoparticles to establish a bioelectrically active and spatially stable microenvironment that promotes spinal cord regeneration through computational analysis(BIOVIA Materials Studio).Hydrogels,known for their biocompatibility and extracellular matrix-mimicking properties,support essential cellular behaviors such as adhesion,proliferation,and migration.The integration of MgFe_(2)O_(4) nanoparticles imparts both electrical conductivity and magnetic responsiveness,enabling controlled transmission of electrical signals that are crucial for guiding cellular processes like differentiation and directed migration.Furthermore,the hydrogel acts as a delivery medium,facilitating the adsorption of MgFe_(2)O_(4) nanoparticles onto spinal tissue through strong Van der Waals and intramolecular interactions.The computational simulations revealed a robust adsorption profile,with a binding distance of 20.180Åand a cumulative adsorption energy of 2740.42 kcal/mol,indicating stable nanoparticle-tissue interactions.Pressure-dependent sorption analysis further demonstrated that reduced pressure conditions enhance adsorption strength,promoting tighter material-tissue integration.The adverse Van der Waals energy and increased intramolecular energy observed under these conditions underscore the importance of optimized adsorption settings for functional tissue interface formation.Altogether,the conductive hydrogel-MgFe_(2)O_(4) composite system offers a promising therapeutic platform by combining structural support,electrical stimulation,and magnetic guidance,thereby enhancing cell-material interactions and fostering an environment conducive to spinal cord tissue repair.
基金acknowledge thorough support from the Global COE program from the Ministry of Education, Culture, Sports and Technology (MEXT) of Japan
文摘A series of linear stability analysis is carried out on the onset of thermal convection in the presence of spatial variations of viscosity, thermal conductivity and expansivity. We consider the temporal evolution of an infinitesimal perturbation superimposed to a static （motionless） and con- ductive state in a basally-heated planar layer. From the changes in flow patterns with increasing the amplitudes of temperature dependence of viscosity, we identified the transition into the ＂stagnant-lid＂ （ST） regime, where the convection occurs only beneath a thick and stagnant-lid of cold fluid at the top surface. Detailed analysis showed a significant increase of the aspect ratio of convection cells in ST regime induced by the spatial variations in thermal conductivity and/or expansivity： the horizon- tal length scale of ST convection can be enlarged by up to 50% with 10 times increase of thermal conductivity with depth. We further developed an analytical model of ST convection which success- fully reproduced the mechanism of increasing horizontal length scale of ST regime convection cells for given spatial variations in physical properties. Our findings may highlight the essential roles of the spatial variation of thermal conductivity on the convection patterns in the mantle.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.21978230)Shaanxi Creative Talents Promotion Plan−Technological Innovation Team(Grant No.2019TD-039).
文摘Chemical looping reforming of methane is a novel and effective approach to convert methane to syngas,in which oxygen transfer is achieved by a redox material.Although lots of efforts have been made to develop high-performance redox materials,a few studies have focused on the redox kinetics.In this work,the kinetics of SrFeO_(3−δ)–CaO∙MnO nanocomposite reduction by methane was investigated both on a thermo-gravimetric analyzer and in a packed-bed microreactor.During the methane reduction,combustion occurs before the partial oxidation and there exists a transition between them.The weight loss due to combustion increases,but the transition region becomes less inconspicuous as the reduction temperature increased.The weight loss associated with the partial oxidation is much larger than that with combustion.The rate of weight loss related to the partial oxidation is well fitted by the Avrami–Erofeyev equation with n=3(A3 model)with an activation energy of 59.8 kJ∙mol^(‒1).The rate law for the partial oxidation includes a solid conversion term whose expression is given by the A3 model and a methane pressure-dependent term represented by a power law.The partial oxidation is half order with respect to methane pressure.The proposed rate law could well predict the reduction kinetics;thus,it may be used to design and/or analyze a chemical looping reforming reactor.
