Energy optimization is one of the key problems for ship roll reduction systems in the last decade. According to the nonlinear characteristics of ship motion, the four degrees of freedom nonlinear model of Fin/Rudder r...Energy optimization is one of the key problems for ship roll reduction systems in the last decade. According to the nonlinear characteristics of ship motion, the four degrees of freedom nonlinear model of Fin/Rudder roll stabilization can be established. This paper analyzes energy consumption caused by overcoming the resistance and the yaw, which is added to the fin/rudder roll stabilization system as new performance index. In order to achieve the purpose of the roll reduction, ship course keeping and energy optimization, the self-tuning PID controller based on the multi-objective genetic algorithm （MOGA） method is used to optimize performance index. In addition, random weight coefficient is adopted to build a multi-objective genetic algorithm optimization model. The objective function is improved so that the objective function can be normalized to a constant level. Simulation results showed that the control method based on MOGA, compared with the traditional control method, not only improves the efficiency of roll stabilization and yaw control precision, but also optimizes the energy of the system. The proposed methodology can get a better performance at different sea states.展开更多
To analyse a possible way to improve the propulsion performance of ships,the unstructured grid and the Reynolds Average Navier-Stokes equations were used to calculate the performance of a propeller and rudder fitted w...To analyse a possible way to improve the propulsion performance of ships,the unstructured grid and the Reynolds Average Navier-Stokes equations were used to calculate the performance of a propeller and rudder fitted with additional thrust fins in the viscous flow field.The computational fluid dynamics software FLUENT was used to simulate the thrust and torque coefficient as a function of the advance coefficient of propeller and the thrust efficiency of additional thrust fins. The pressure and velocity flow behind the propeller was calculated. The geometrical nodes of the propeller were constituted by FORTRAN program and the NUMBS method was used to create a configuration of the propeller,which was then used by GAMMBIT to generate the calculation model. The thrust efficiency of fins was calculated as a function of the number of additional fins and the attack angles. The results of the calculations agree fairly well with experimental data,which shows that the viscous flow solution we present is useful in simulating the performance of propellers and rudders with additional fins.展开更多
The Reynolds-averaged Navier-Stokes (RANS) method, along with the Fluent software package, was used to study the steady and unsteady interaction of propellers and rudders with additional thrust fins.The sliding mesh m...The Reynolds-averaged Navier-Stokes (RANS) method, along with the Fluent software package, was used to study the steady and unsteady interaction of propellers and rudders with additional thrust fins.The sliding mesh model was employed to simulate unsteady interactions between the blades, the rudder and the thrust fins.Based on the numerical results, the pressure distribution on the propeller and the efficiency of the fins were calculated as a function of the attack angle.The RANS results were compared with results calculated by the potential method.It was found that the results for the potential method and the RANS method have good consistency, but they yield maximum efficiencies for the fins, and thus corresponding attack angles, that are not identical.展开更多
Fins are extensively utilized in heat exchangers and various industrial applications as they are lightweight and can benefit in various systems,including electronic cooling devices and automotive components,owing to t...Fins are extensively utilized in heat exchangers and various industrial applications as they are lightweight and can benefit in various systems,including electronic cooling devices and automotive components,owing to their adaptable design.Furthermore,spine fins are introduced to improve performance in applications such as automotive radiators.They can be shaped in different ways and constructed from a collection of materials.Inspired by this,the present model examines the effects of internal heat generation and radiation-convection on the thermal distribution in a wetted convex-shaped spine fin.Using dimensionless terms,the proposed fin model involving a governing nonlinear ordinary differential equation(ODE)is transformed into a dimensionless form.The study uses the operational matrix with the Charlier polynomial collocation method(OMCCM)to ensure precise and computationally efficient numerical solutions for the dimensionless equation.In order to aid in the analysis of thermal performance,the importance of major parameters on the temperature profile is graphically illustrated.The main outcome of the study reveals that as the radiation-conductive,wet,and convective-conductive parameters increase,the heat transfer rate progressively improves.Conversely,the ambient temperature and internal heat generation parameters show an inverse relationship.展开更多
In this paper,a series of flutter simulations are carried out to investigate the effects of split drag rudder(SDR)on the transonic flutter characteristic of rigid NACA 64A010.A structural dynamic model addressing two-...In this paper,a series of flutter simulations are carried out to investigate the effects of split drag rudder(SDR)on the transonic flutter characteristic of rigid NACA 64A010.A structural dynamic model addressing two-degree-of-freedom pitch-plunge aeroelastic oscillations was coupled with the unsteady Reynolds-averaged Navier-Stokes equations to perform flutter simulation.Meanwhile,the influence mechanism of SDR on flutter boundary is explained through aerodynamic work and the correlated shock wave location.The results show that the SDR delays the shock wave shifting downstream,and the Mach number corresponding to reaching freeze region increases as the split angle increases.Therefore,the peak value of aerodynamic moment coefficient amplitude and the sharp ascent process of phase occurs at higher Mach number,which leads to the delay in the occurrence of the transonic dip.Besides,before the transonic dip of airfoil without SDR occurs,the aerodynamic moment phase of airfoil with the SDR decreases slowly due to the decrease in the speed of shock wave moving downstream.This results in an increased flutter speed when employing the SDR before the transonic dip of airfoil without SDR occurs.Meanwhile,the effects of asymmetric split angles on the transonic flutter characteristics are also investigated.Before the transonic dip of airfoil without SDR occurs,the flutter characteristic is dominated by the smaller split angle.展开更多
A distinguished category of operational fluids,known as hybrid nanofluids,occupies a prominent role among various fluid types owing to its superior heat transfer properties.By employing a dovetail fin profile,this wor...A distinguished category of operational fluids,known as hybrid nanofluids,occupies a prominent role among various fluid types owing to its superior heat transfer properties.By employing a dovetail fin profile,this work investigates the thermal reaction of a dynamic fin system to a hybrid nanofluid with shape-based properties,flowing uniformly at a velocity U.The analysis focuses on four distinct types of nanoparticles,i.e.,Al2O3,Ag,carbon nanotube(CNT),and graphene.Specifically,two of these particles exhibit a spherical shape,one possesses a cylindrical form,and the final type adopts a platelet morphology.The investigation delves into the pairing of these nanoparticles.The examination employs a combined approach to assess the constructional and thermal exchange characteristics of the hybrid nanofluid.The fin design,under the specified circumstances,gives rise to the derivation of a differential equation.The given equation is then transformed into a dimensionless form.Notably,the Hermite wavelet method is introduced for the first time to address the challenge posed by a moving fin submerged in a hybrid nanofluid with shape-dependent features.To validate the credibility of this research,the results obtained in this study are systematically compared with the numerical simulations.The examination discloses that the highest heat flux is achieved when combining nanoparticles with spherical and platelet shapes.展开更多
This work presents a simulation analysis using a multi-objective evolutionary algorithm for the thermo-hydraulic behavior of staggered heat sinks whose fins have NACA 0040 airfoil profile.The results were compared wit...This work presents a simulation analysis using a multi-objective evolutionary algorithm for the thermo-hydraulic behavior of staggered heat sinks whose fins have NACA 0040 airfoil profile.The results were compared with a conventional pin fin heat sink with a circular profile.This study searched for the best thermo-hydraulic performance by translational and rotational positioning of the fins.It is worth mentioning that this work was carried out in two stages.In the first stage,the thermo-hydraulic behavior of the heat sink was studied moving the location of the upper array above the X-axis from to 2.25 mm and above the Y-axis from to 1.275 mm.The second stage examined-2.25-1.55the effects of fin rotation considering the results found in stage 1.However,in this second stage,both arrays were free to rotate.For the upper array,the rotation range was-25°to 25° and for the lower array the rotation range was-15° to 15°.It is worth mentioning that both stages were analyzed for a single Reynolds(Re)number value of 13,000.The optimization results using the multi-objective evolutionary algorithm showed that compared to a NACA 0040 heat sink with fixed,unrotated original configuration(C0),the NACA 0040 heat sink with any Position Configuration(PC)did not significantly improve the heat transfer.Then,the results found in the second stage showed that the effect of the rotation of both sets did not influence the increase in pressure drop.However,it was found that with the Optimal Position and Rotation Configuration(PRCoptimal),which is the optimized array from Stage 1(position)then optimized by rotation,there is a slightly higher Performance Evaluation Criterion(PEC)compared to the original C0 configuration by 7%.Finally,the proposed NACA 0040 heat sink with the optimal rotation and position setting(PRCoptimal)was found to have a PEC of 9%compared to a conventional pin fin heat sink.展开更多
In this study,four types of spiral fins with varying parameters were mounted on an upstream cylinder,and the effects of spiral fins on the vibration response of heat exchange tubes and the vortex structure in cross fl...In this study,four types of spiral fins with varying parameters were mounted on an upstream cylinder,and the effects of spiral fins on the vibration response of heat exchange tubes and the vortex structure in cross flow were studied through experiments and numerical simulations.The results indicate a strong dependency of the cylinder's vibration response on the fin parameters.The results indicate that the vibration response and wake structure of the cylinder are significantly influenced by the parameters of the fins.The introduction of a finned cylinder affects both its own vibration amplitude and frequency,as well as the downstream cylinder.The amplitudes of finned cylinders Ⅰ and Ⅲ are reduced by 57.8% and 59.9%,respectively,compared to the bare cylinder.This reduction helps to restrain vibration and diminishes the amplitudes of the downstream cylinder.Although finned cylinder Ⅱ slightly decreases its own vibration,it increases the amplitude of the downstream cylinder by 13.7%.The mean drag coefficient and the root mean square of the lift coefficient of the finned cylinder are higher than those of the bare cylinder when the finned cylinder is positioned upstream.Smaller pitch and larger equivalent diameter will lead to increased drag,resulting in enhanced vortex shedding in the wake,which amplifies the vibrations of the cylinder in that wake.The downstream of finned cylinder Ⅱ has the widest wake and higher vortex strength,and the dynamic load and vibration of the downstream cylinder are increased.The vortex intensity decays faster in the wake of finned cylinder Ⅲ,and the vibration of the downstream cylinder is weaker.展开更多
This study presents a simplified numerical approach for evaluating the thermal performance of louvered fin and flat tube heat exchangers(LFFTHXs),which are critical in many thermal management applications but difficul...This study presents a simplified numerical approach for evaluating the thermal performance of louvered fin and flat tube heat exchangers(LFFTHXs),which are critical in many thermal management applications but difficult to model due to their complex geometries.The proposed method uses an equivalent convective heat transfer coefficient to represent the fins,significantly reducing the computational requirements of the simulations.Validation against the effectiveness-number of transfer units method showed average deviations of 4.4%for the novel louvered fin with two combined holes and 9.5%for conventional configurations,confirming the accuracy of the method.Further application to two-phase refrigerant scenarios using experimental data demonstrated the robustness of the method and its suitability for practical design and optimization of LFFTHXs.The approach not only improves the feasibility of thermal analysis in industrial applications but also provides a foundation for future research into more efficient heat exchanger designs.展开更多
The growing need for enhanced heat dissipation is compelling the development of more effective heat exchangers.Innovation inspired by nature bionics,four types of leaf-shaped pin fins were proposed and four combinatio...The growing need for enhanced heat dissipation is compelling the development of more effective heat exchangers.Innovation inspired by nature bionics,four types of leaf-shaped pin fins were proposed and four combinations of them were considered.The leaf-shaped design of the cooling pin fin enhances uniformity and synergy,effectively creating an optimized flow path that boosts cooling performance.Eight three-dimensional conjugate heat transfer models in staggered arrangement were developed using ANSYS-Fluent software.Aluminum6061material was used as the heat sinkmaterial and single-phase liquid water flowed through the rectangular channel where the Reynolds(R_(e))number varies from 40 to 100.Using the same boundary conditions as the software simulations,two leaf-shaped channels were printed to validate numerical models.Velocity field and temperature differences of the eight proposed leaf-shaped pin fins configurations were discussed by comparison with cylindrical pin fins.Based on the findings of this study,at a Reynolds number of 80,the Leaf B Staggered Array(LBSA)records a maximum temperature that is 0.72 K lower than that of the cylindrical pin fins arrangement.Additionally,the LBSA exhibits a reduction in the friction factor by approximately 33.3%relative to the circular pin fins array under the same R_(e).This implies that the design of LBSA has been optimized to provide better heat dissipation performance while maintaining lower energy consumption.Furthermore,the LBSA demonstrates the most favorable thermal-hydraulic performance index(TPI),which is 1.18 times higher than that of the circular pin fins arrangement at R_(e)=80.The temperature reduction and friction factor reduction of the lobed channel is more pronounced than that of the conventional cooling channel,highlighting its potential to increase heat transfer efficiency and reduce energy consumption in practical applications.展开更多
Fish cell line provide a useful tool for studies in virology and molecular biology.To establish a novel continuous marine fish cell line(EFF)from caudal fin tissue of brown-marbled grouper Epinephelus fuscoguttatus,it...Fish cell line provide a useful tool for studies in virology and molecular biology.To establish a novel continuous marine fish cell line(EFF)from caudal fin tissue of brown-marbled grouper Epinephelus fuscoguttatus,its susceptibility to the crustacean covert mortality nodavirus(CMNV)was evaluated.The primary cell cultures were initiated first by incomplete digestion of fin tissue blocks with dispase and collagenase,and then the explant was cultured in L-15 medium supplemented with 20%fetal bovine serum,10%grouper muscle extract,and 20-ng/mL growth factors of basic fibroblast growth factor(bFGF)and epidermal growth factor(EGF).The EFF cells were continuously passaged beyond 50 times in fibroblast-like morphology,and they grew well in L-15 medium supplemented with a lower concentration fetal bovine serum(10%)at 28℃ after passage 10,without muscle extract and the growth factors.In addition,their grouper origin was confirmed by chromosome analysis and cytochrome oxidase 1(CO 1)gene analysis of these EFF cells.Transfection experiment via lipofectamine 8000 indicated that the EFF cells had a high transfection potential with a transfection efficiency up to 32%.Cross-species viral susceptibility analysis showed that CMNV not only successfully infected the EFF cells as evidenced by obvious cytopathic effects like vacuolation,detachment and death of cells,but also multiplied in the EFF cells as indicated by the results of semi-quantitative RT-PCR in transmission electron microscopy.Therefore,the establishment of immortal EFF cell line provided a useful cell model for future works on the isolation,multiplication,and pathogenic mechanism of cross-species infection of CMNV as well as genetic manipulation.展开更多
目的:评价丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用的有效性。方法:计算机检索中国生物医学文献数据库、中国期刊全文数据库、万方期刊数据库等相关资料,按照Cochrane系统评价的方法,客观评价纳入研究的质量,提取有效数据,采用Rev Man...目的:评价丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用的有效性。方法:计算机检索中国生物医学文献数据库、中国期刊全文数据库、万方期刊数据库等相关资料,按照Cochrane系统评价的方法,客观评价纳入研究的质量,提取有效数据,采用Rev Man 5.2软件进行Meta分析。结果:共纳入5个随机对照试验,包括294例患者。结果显示,丹蛭降糖胶囊能降低2型糖尿病患者FINS[MD=1.24,95%CI(0.90,1.59),P<0.01],降低IRI[MD=0.20,95%CI(0.14,0.27),P<0.01]。结论:丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用是有效的。展开更多
以欧姆龙公司CP1H型号的PLC为应用背景,设计了基于Host Link FINS协议的PLC设备远程监控系统。该文提出了基于串口的远程通信方案,并且详细分析了Host Link FINS协议的结构和指令格式,用MFC实现了监控软件的设计,完成监控软件与欧姆龙PL...以欧姆龙公司CP1H型号的PLC为应用背景,设计了基于Host Link FINS协议的PLC设备远程监控系统。该文提出了基于串口的远程通信方案,并且详细分析了Host Link FINS协议的结构和指令格式,用MFC实现了监控软件的设计,完成监控软件与欧姆龙PLC的数据通信功能,实现监控软件对PLC的远程监控。经过现场的测试和运行,该监控系统稳定可靠,性能较高。展开更多
基金Foundation item： Supported by the National Natural Science Foundation of China （Grant No. 61174047） and the Fundamental Research Funds for the Central Universities （HEUCF041406）.
文摘Energy optimization is one of the key problems for ship roll reduction systems in the last decade. According to the nonlinear characteristics of ship motion, the four degrees of freedom nonlinear model of Fin/Rudder roll stabilization can be established. This paper analyzes energy consumption caused by overcoming the resistance and the yaw, which is added to the fin/rudder roll stabilization system as new performance index. In order to achieve the purpose of the roll reduction, ship course keeping and energy optimization, the self-tuning PID controller based on the multi-objective genetic algorithm （MOGA） method is used to optimize performance index. In addition, random weight coefficient is adopted to build a multi-objective genetic algorithm optimization model. The objective function is improved so that the objective function can be normalized to a constant level. Simulation results showed that the control method based on MOGA, compared with the traditional control method, not only improves the efficiency of roll stabilization and yaw control precision, but also optimizes the energy of the system. The proposed methodology can get a better performance at different sea states.
文摘To analyse a possible way to improve the propulsion performance of ships,the unstructured grid and the Reynolds Average Navier-Stokes equations were used to calculate the performance of a propeller and rudder fitted with additional thrust fins in the viscous flow field.The computational fluid dynamics software FLUENT was used to simulate the thrust and torque coefficient as a function of the advance coefficient of propeller and the thrust efficiency of additional thrust fins. The pressure and velocity flow behind the propeller was calculated. The geometrical nodes of the propeller were constituted by FORTRAN program and the NUMBS method was used to create a configuration of the propeller,which was then used by GAMMBIT to generate the calculation model. The thrust efficiency of fins was calculated as a function of the number of additional fins and the attack angles. The results of the calculations agree fairly well with experimental data,which shows that the viscous flow solution we present is useful in simulating the performance of propellers and rudders with additional fins.
基金Supported by the National Natural Science Foundation of China under Grant No.10702016the Fundamental Research Funds for the Central Universities No.HEUCFT1001
文摘The Reynolds-averaged Navier-Stokes (RANS) method, along with the Fluent software package, was used to study the steady and unsteady interaction of propellers and rudders with additional thrust fins.The sliding mesh model was employed to simulate unsteady interactions between the blades, the rudder and the thrust fins.Based on the numerical results, the pressure distribution on the propeller and the efficiency of the fins were calculated as a function of the attack angle.The RANS results were compared with results calculated by the potential method.It was found that the results for the potential method and the RANS method have good consistency, but they yield maximum efficiencies for the fins, and thus corresponding attack angles, that are not identical.
基金the Deanship of Research and Graduate Studies at King Khalid University for funding this work through Large Research Project under grant number RGP2/308/46。
文摘Fins are extensively utilized in heat exchangers and various industrial applications as they are lightweight and can benefit in various systems,including electronic cooling devices and automotive components,owing to their adaptable design.Furthermore,spine fins are introduced to improve performance in applications such as automotive radiators.They can be shaped in different ways and constructed from a collection of materials.Inspired by this,the present model examines the effects of internal heat generation and radiation-convection on the thermal distribution in a wetted convex-shaped spine fin.Using dimensionless terms,the proposed fin model involving a governing nonlinear ordinary differential equation(ODE)is transformed into a dimensionless form.The study uses the operational matrix with the Charlier polynomial collocation method(OMCCM)to ensure precise and computationally efficient numerical solutions for the dimensionless equation.In order to aid in the analysis of thermal performance,the importance of major parameters on the temperature profile is graphically illustrated.The main outcome of the study reveals that as the radiation-conductive,wet,and convective-conductive parameters increase,the heat transfer rate progressively improves.Conversely,the ambient temperature and internal heat generation parameters show an inverse relationship.
文摘In this paper,a series of flutter simulations are carried out to investigate the effects of split drag rudder(SDR)on the transonic flutter characteristic of rigid NACA 64A010.A structural dynamic model addressing two-degree-of-freedom pitch-plunge aeroelastic oscillations was coupled with the unsteady Reynolds-averaged Navier-Stokes equations to perform flutter simulation.Meanwhile,the influence mechanism of SDR on flutter boundary is explained through aerodynamic work and the correlated shock wave location.The results show that the SDR delays the shock wave shifting downstream,and the Mach number corresponding to reaching freeze region increases as the split angle increases.Therefore,the peak value of aerodynamic moment coefficient amplitude and the sharp ascent process of phase occurs at higher Mach number,which leads to the delay in the occurrence of the transonic dip.Besides,before the transonic dip of airfoil without SDR occurs,the aerodynamic moment phase of airfoil with the SDR decreases slowly due to the decrease in the speed of shock wave moving downstream.This results in an increased flutter speed when employing the SDR before the transonic dip of airfoil without SDR occurs.Meanwhile,the effects of asymmetric split angles on the transonic flutter characteristics are also investigated.Before the transonic dip of airfoil without SDR occurs,the flutter characteristic is dominated by the smaller split angle.
文摘A distinguished category of operational fluids,known as hybrid nanofluids,occupies a prominent role among various fluid types owing to its superior heat transfer properties.By employing a dovetail fin profile,this work investigates the thermal reaction of a dynamic fin system to a hybrid nanofluid with shape-based properties,flowing uniformly at a velocity U.The analysis focuses on four distinct types of nanoparticles,i.e.,Al2O3,Ag,carbon nanotube(CNT),and graphene.Specifically,two of these particles exhibit a spherical shape,one possesses a cylindrical form,and the final type adopts a platelet morphology.The investigation delves into the pairing of these nanoparticles.The examination employs a combined approach to assess the constructional and thermal exchange characteristics of the hybrid nanofluid.The fin design,under the specified circumstances,gives rise to the derivation of a differential equation.The given equation is then transformed into a dimensionless form.Notably,the Hermite wavelet method is introduced for the first time to address the challenge posed by a moving fin submerged in a hybrid nanofluid with shape-dependent features.To validate the credibility of this research,the results obtained in this study are systematically compared with the numerical simulations.The examination discloses that the highest heat flux is achieved when combining nanoparticles with spherical and platelet shapes.
基金funded by University of Guanajuato through Project Convocatoria Institucional de Investigacion Cientifica 2025,161/2025.
文摘This work presents a simulation analysis using a multi-objective evolutionary algorithm for the thermo-hydraulic behavior of staggered heat sinks whose fins have NACA 0040 airfoil profile.The results were compared with a conventional pin fin heat sink with a circular profile.This study searched for the best thermo-hydraulic performance by translational and rotational positioning of the fins.It is worth mentioning that this work was carried out in two stages.In the first stage,the thermo-hydraulic behavior of the heat sink was studied moving the location of the upper array above the X-axis from to 2.25 mm and above the Y-axis from to 1.275 mm.The second stage examined-2.25-1.55the effects of fin rotation considering the results found in stage 1.However,in this second stage,both arrays were free to rotate.For the upper array,the rotation range was-25°to 25° and for the lower array the rotation range was-15° to 15°.It is worth mentioning that both stages were analyzed for a single Reynolds(Re)number value of 13,000.The optimization results using the multi-objective evolutionary algorithm showed that compared to a NACA 0040 heat sink with fixed,unrotated original configuration(C0),the NACA 0040 heat sink with any Position Configuration(PC)did not significantly improve the heat transfer.Then,the results found in the second stage showed that the effect of the rotation of both sets did not influence the increase in pressure drop.However,it was found that with the Optimal Position and Rotation Configuration(PRCoptimal),which is the optimized array from Stage 1(position)then optimized by rotation,there is a slightly higher Performance Evaluation Criterion(PEC)compared to the original C0 configuration by 7%.Finally,the proposed NACA 0040 heat sink with the optimal rotation and position setting(PRCoptimal)was found to have a PEC of 9%compared to a conventional pin fin heat sink.
基金financially supported by the National Natural Science Foundation of China(22478286)。
文摘In this study,four types of spiral fins with varying parameters were mounted on an upstream cylinder,and the effects of spiral fins on the vibration response of heat exchange tubes and the vortex structure in cross flow were studied through experiments and numerical simulations.The results indicate a strong dependency of the cylinder's vibration response on the fin parameters.The results indicate that the vibration response and wake structure of the cylinder are significantly influenced by the parameters of the fins.The introduction of a finned cylinder affects both its own vibration amplitude and frequency,as well as the downstream cylinder.The amplitudes of finned cylinders Ⅰ and Ⅲ are reduced by 57.8% and 59.9%,respectively,compared to the bare cylinder.This reduction helps to restrain vibration and diminishes the amplitudes of the downstream cylinder.Although finned cylinder Ⅱ slightly decreases its own vibration,it increases the amplitude of the downstream cylinder by 13.7%.The mean drag coefficient and the root mean square of the lift coefficient of the finned cylinder are higher than those of the bare cylinder when the finned cylinder is positioned upstream.Smaller pitch and larger equivalent diameter will lead to increased drag,resulting in enhanced vortex shedding in the wake,which amplifies the vibrations of the cylinder in that wake.The downstream of finned cylinder Ⅱ has the widest wake and higher vortex strength,and the dynamic load and vibration of the downstream cylinder are increased.The vortex intensity decays faster in the wake of finned cylinder Ⅲ,and the vibration of the downstream cylinder is weaker.
基金supported by the National Natural Science Foundation of China(Grant No.12272345).
文摘This study presents a simplified numerical approach for evaluating the thermal performance of louvered fin and flat tube heat exchangers(LFFTHXs),which are critical in many thermal management applications but difficult to model due to their complex geometries.The proposed method uses an equivalent convective heat transfer coefficient to represent the fins,significantly reducing the computational requirements of the simulations.Validation against the effectiveness-number of transfer units method showed average deviations of 4.4%for the novel louvered fin with two combined holes and 9.5%for conventional configurations,confirming the accuracy of the method.Further application to two-phase refrigerant scenarios using experimental data demonstrated the robustness of the method and its suitability for practical design and optimization of LFFTHXs.The approach not only improves the feasibility of thermal analysis in industrial applications but also provides a foundation for future research into more efficient heat exchanger designs.
基金supported by the Shandong Provincial Natural Science Foundation,China(Grant ZR2024ME136).
文摘The growing need for enhanced heat dissipation is compelling the development of more effective heat exchangers.Innovation inspired by nature bionics,four types of leaf-shaped pin fins were proposed and four combinations of them were considered.The leaf-shaped design of the cooling pin fin enhances uniformity and synergy,effectively creating an optimized flow path that boosts cooling performance.Eight three-dimensional conjugate heat transfer models in staggered arrangement were developed using ANSYS-Fluent software.Aluminum6061material was used as the heat sinkmaterial and single-phase liquid water flowed through the rectangular channel where the Reynolds(R_(e))number varies from 40 to 100.Using the same boundary conditions as the software simulations,two leaf-shaped channels were printed to validate numerical models.Velocity field and temperature differences of the eight proposed leaf-shaped pin fins configurations were discussed by comparison with cylindrical pin fins.Based on the findings of this study,at a Reynolds number of 80,the Leaf B Staggered Array(LBSA)records a maximum temperature that is 0.72 K lower than that of the cylindrical pin fins arrangement.Additionally,the LBSA exhibits a reduction in the friction factor by approximately 33.3%relative to the circular pin fins array under the same R_(e).This implies that the design of LBSA has been optimized to provide better heat dissipation performance while maintaining lower energy consumption.Furthermore,the LBSA demonstrates the most favorable thermal-hydraulic performance index(TPI),which is 1.18 times higher than that of the circular pin fins arrangement at R_(e)=80.The temperature reduction and friction factor reduction of the lobed channel is more pronounced than that of the conventional cooling channel,highlighting its potential to increase heat transfer efficiency and reduce energy consumption in practical applications.
基金Supported by the Key Research&Development Program of Shandong Province(No.2023 CXGC 010710)the National Natural Science Foundation of China(No.32273116)the Fundamental Research Funds for the Central Universities(No.202261023)。
文摘Fish cell line provide a useful tool for studies in virology and molecular biology.To establish a novel continuous marine fish cell line(EFF)from caudal fin tissue of brown-marbled grouper Epinephelus fuscoguttatus,its susceptibility to the crustacean covert mortality nodavirus(CMNV)was evaluated.The primary cell cultures were initiated first by incomplete digestion of fin tissue blocks with dispase and collagenase,and then the explant was cultured in L-15 medium supplemented with 20%fetal bovine serum,10%grouper muscle extract,and 20-ng/mL growth factors of basic fibroblast growth factor(bFGF)and epidermal growth factor(EGF).The EFF cells were continuously passaged beyond 50 times in fibroblast-like morphology,and they grew well in L-15 medium supplemented with a lower concentration fetal bovine serum(10%)at 28℃ after passage 10,without muscle extract and the growth factors.In addition,their grouper origin was confirmed by chromosome analysis and cytochrome oxidase 1(CO 1)gene analysis of these EFF cells.Transfection experiment via lipofectamine 8000 indicated that the EFF cells had a high transfection potential with a transfection efficiency up to 32%.Cross-species viral susceptibility analysis showed that CMNV not only successfully infected the EFF cells as evidenced by obvious cytopathic effects like vacuolation,detachment and death of cells,but also multiplied in the EFF cells as indicated by the results of semi-quantitative RT-PCR in transmission electron microscopy.Therefore,the establishment of immortal EFF cell line provided a useful cell model for future works on the isolation,multiplication,and pathogenic mechanism of cross-species infection of CMNV as well as genetic manipulation.
文摘目的:评价丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用的有效性。方法:计算机检索中国生物医学文献数据库、中国期刊全文数据库、万方期刊数据库等相关资料,按照Cochrane系统评价的方法,客观评价纳入研究的质量,提取有效数据,采用Rev Man 5.2软件进行Meta分析。结果:共纳入5个随机对照试验,包括294例患者。结果显示,丹蛭降糖胶囊能降低2型糖尿病患者FINS[MD=1.24,95%CI(0.90,1.59),P<0.01],降低IRI[MD=0.20,95%CI(0.14,0.27),P<0.01]。结论:丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用是有效的。
文摘以欧姆龙公司CP1H型号的PLC为应用背景,设计了基于Host Link FINS协议的PLC设备远程监控系统。该文提出了基于串口的远程通信方案,并且详细分析了Host Link FINS协议的结构和指令格式,用MFC实现了监控软件的设计,完成监控软件与欧姆龙PLC的数据通信功能,实现监控软件对PLC的远程监控。经过现场的测试和运行,该监控系统稳定可靠,性能较高。
