Currently,researchers worldwide are conducting theoretical and experimental studies to understand the significance of nanofluids in heat transfer processes.These fluids are created by dispersing nanoparticles in a bas...Currently,researchers worldwide are conducting theoretical and experimental studies to understand the significance of nanofluids in heat transfer processes.These fluids are created by dispersing nanoparticles in a base fluid.Experiments have demonstrated that nanofluids exhibit superior and more attractive thermal properties compared to conventional fluids.In this current study,we discuss about the heat transfer enhancement of unsteady incompressible laminar couple stress nanofluid flow with Magnetohydrodynamics(MHD)between parallel plates.Prescribed temperature boundary conditions of the surface are employed on the porous surface and it is assumed that the temperature changes periodically over time on the plates.The flow is provoked by periodic suction as well as injection at the plates.With the aid of similarity variables,the system of governing transport equations is transformed into a nonlinear system of ordinary differential equations which is subsequently solved using shooting method along with Runge-Kutta fourth order scheme.The obtained results are shown graphically and explained for the non-dimensional velocity,heat profiles with diverse fluid parameters as well as geometric parameters.Nusselt number is calculated at the lower and upper plates.It is found that temperature component of the fluid is augmenting with suction-injection parameter,whereas it is decreasing in nature with respect to Reynolds number.展开更多
High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts.In this work,we revisit the framework of magnetohydrodynamic(MHD)theory and introduce a new analytical appr...High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts.In this work,we revisit the framework of magnetohydrodynamic(MHD)theory and introduce a new analytical approach for examining plasma jets generated by intense laser-plasma interactions.Specifically,we reformulate the fundamental MHD equations to elucidate the governing factors of local plasma density evolution.Furthermore,MHD simulations of laser irradiation on planar targets demonstrate that impact pressure plays a dominant role in the propagation of high-Mach-number plasma jets.In addition,a pronounced dependence on the atomic number is identified:higher-Z materials amplify the impact pressure,suggesting that metallicity exerts a significant influence on the morphology and dynamics of astrophysical jets.展开更多
Quasi-hemispherical magnetized collisionless shocks have been generated at the SG-II laser facility through the interaction between a laserproduced supersonic plasma flow and a magnetized ambient plasma,exhibiting an ...Quasi-hemispherical magnetized collisionless shocks have been generated at the SG-II laser facility through the interaction between a laserproduced supersonic plasma flow and a magnetized ambient plasma,exhibiting an angular asymmetric shock profile accompanied by asymmetric ion acceleration.We have conducted test particle simulations using the electromagnetic fields derived from 2D MHD simulations to investigate the asymmetry of ion acceleration.The simulations reproduce the angular asymmetry of the shock and the ion acceleration observed in experiments.The results indicate that shock drift acceleration is the primary mechanism for ion energization in the present quasiperpendicular magnetized shock.The asymmetric shock structure caused by nonuniform ambient plasma forms an asymmetric accelerated electric field,ultimately leading to angular asymmetric ion acceleration,which is consistent with space observations and our experimental results.Our study provides a plausible explanation for the discrepancies reported in previous ion acceleration experiments,and could contribute to understanding of the collisionless shock acceleration.展开更多
维持性血液透析(maintenance hemodialysis,MHD)是终末期肾脏病患者肾脏替代治疗中发展最早、应用最广泛的治疗方式[1],随着慢性肾脏病发病率的提高[2],MHD患者人群亦逐年增多。且随着透析时间的延长、残余肾功能的丧失,血液透析相关的...维持性血液透析(maintenance hemodialysis,MHD)是终末期肾脏病患者肾脏替代治疗中发展最早、应用最广泛的治疗方式[1],随着慢性肾脏病发病率的提高[2],MHD患者人群亦逐年增多。且随着透析时间的延长、残余肾功能的丧失,血液透析相关的并发症亦逐渐增多并显现[3],而睡眠障碍[4]及营养不良[5]作为MHD患者最常见并发症,直接影响着MHD患者的健康相关生活质量(health related quality of life,HRQOL)。本研究对中国边境地区西双版纳傣族自治州勐腊县人民医院的MHD患者进行睡眠及营养状况的调查评估,分析并探讨影响MHD患者睡眠质量及营养状况的影响因素及其之间的关系,为进一步研究相应的预防措施及干预手段提供思路和方法。展开更多
本文对托卡马克的符号辅助计算特征值和线性求解程序(symbolic computation aided eigenvalue and linear code for Tokamaks,SCELT)进行了并行开发及功能拓展。具体为优化了非均匀网格加密的功能,提高了程序的收敛速度和收敛精度;增加...本文对托卡马克的符号辅助计算特征值和线性求解程序(symbolic computation aided eigenvalue and linear code for Tokamaks,SCELT)进行了并行开发及功能拓展。具体为优化了非均匀网格加密的功能,提高了程序的收敛速度和收敛精度;增加了程序对稀疏矩阵功能的支持,减少了程序对内存的消耗;使用并行思想和信息传递接口(message passing interface,MPI)技术对程序数值离散模块并行开发,通过多进程并行提高了程序数值离散的效率。同时,基于特征值问题计算的可扩展库(the scalable library for eigenvalue problem computations,SLEPc)特征值求解库为程序添加了大规模稀疏矩阵特征值并行求解功能,提高了程序研究问题的速度以及规模。通过计算内扭曲模(m=1,n=1)和电阻撕裂模(m=2,n=1)的线性增长率和模结构验证了并行及拓展后的程序的可靠性。此外,通过与初始版本的运行结果进行比较,展示了优化后的程序在运行速度、运行规模上的巨大优势,以及程序在研究复杂的磁流体动力学(magnetohydrodynamic,MHD)特征值问题的潜力。展开更多
文摘Currently,researchers worldwide are conducting theoretical and experimental studies to understand the significance of nanofluids in heat transfer processes.These fluids are created by dispersing nanoparticles in a base fluid.Experiments have demonstrated that nanofluids exhibit superior and more attractive thermal properties compared to conventional fluids.In this current study,we discuss about the heat transfer enhancement of unsteady incompressible laminar couple stress nanofluid flow with Magnetohydrodynamics(MHD)between parallel plates.Prescribed temperature boundary conditions of the surface are employed on the porous surface and it is assumed that the temperature changes periodically over time on the plates.The flow is provoked by periodic suction as well as injection at the plates.With the aid of similarity variables,the system of governing transport equations is transformed into a nonlinear system of ordinary differential equations which is subsequently solved using shooting method along with Runge-Kutta fourth order scheme.The obtained results are shown graphically and explained for the non-dimensional velocity,heat profiles with diverse fluid parameters as well as geometric parameters.Nusselt number is calculated at the lower and upper plates.It is found that temperature component of the fluid is augmenting with suction-injection parameter,whereas it is decreasing in nature with respect to Reynolds number.
基金supported by the National Natural Science Foundation of China(Grant Nos.12325305,12175018,and 12135001)the National Key RD Program of China(Grant Nos.2022YFA1603200 and 2022YFA1603203).
文摘High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts.In this work,we revisit the framework of magnetohydrodynamic(MHD)theory and introduce a new analytical approach for examining plasma jets generated by intense laser-plasma interactions.Specifically,we reformulate the fundamental MHD equations to elucidate the governing factors of local plasma density evolution.Furthermore,MHD simulations of laser irradiation on planar targets demonstrate that impact pressure plays a dominant role in the propagation of high-Mach-number plasma jets.In addition,a pronounced dependence on the atomic number is identified:higher-Z materials amplify the impact pressure,suggesting that metallicity exerts a significant influence on the morphology and dynamics of astrophysical jets.
基金supported by the National Natural Science Foundation of China(Grant Nos.12205298 and 12175230)the Natural Science Foundation of Heilongjiang Province of China(Grant No.LH2024A010)+1 种基金the Fundamental Research Funds for the Central Universities,Controversial and Disruptive Projects of the Chinese Academy of Sciences(Grant No.FGSDFX-0001)the USTC Research Funds of the Double First-Class Initiative(Grant No.YD2140002006).
文摘Quasi-hemispherical magnetized collisionless shocks have been generated at the SG-II laser facility through the interaction between a laserproduced supersonic plasma flow and a magnetized ambient plasma,exhibiting an angular asymmetric shock profile accompanied by asymmetric ion acceleration.We have conducted test particle simulations using the electromagnetic fields derived from 2D MHD simulations to investigate the asymmetry of ion acceleration.The simulations reproduce the angular asymmetry of the shock and the ion acceleration observed in experiments.The results indicate that shock drift acceleration is the primary mechanism for ion energization in the present quasiperpendicular magnetized shock.The asymmetric shock structure caused by nonuniform ambient plasma forms an asymmetric accelerated electric field,ultimately leading to angular asymmetric ion acceleration,which is consistent with space observations and our experimental results.Our study provides a plausible explanation for the discrepancies reported in previous ion acceleration experiments,and could contribute to understanding of the collisionless shock acceleration.
文摘维持性血液透析(maintenance hemodialysis,MHD)是终末期肾脏病患者肾脏替代治疗中发展最早、应用最广泛的治疗方式[1],随着慢性肾脏病发病率的提高[2],MHD患者人群亦逐年增多。且随着透析时间的延长、残余肾功能的丧失,血液透析相关的并发症亦逐渐增多并显现[3],而睡眠障碍[4]及营养不良[5]作为MHD患者最常见并发症,直接影响着MHD患者的健康相关生活质量(health related quality of life,HRQOL)。本研究对中国边境地区西双版纳傣族自治州勐腊县人民医院的MHD患者进行睡眠及营养状况的调查评估,分析并探讨影响MHD患者睡眠质量及营养状况的影响因素及其之间的关系,为进一步研究相应的预防措施及干预手段提供思路和方法。
文摘本文对托卡马克的符号辅助计算特征值和线性求解程序(symbolic computation aided eigenvalue and linear code for Tokamaks,SCELT)进行了并行开发及功能拓展。具体为优化了非均匀网格加密的功能,提高了程序的收敛速度和收敛精度;增加了程序对稀疏矩阵功能的支持,减少了程序对内存的消耗;使用并行思想和信息传递接口(message passing interface,MPI)技术对程序数值离散模块并行开发,通过多进程并行提高了程序数值离散的效率。同时,基于特征值问题计算的可扩展库(the scalable library for eigenvalue problem computations,SLEPc)特征值求解库为程序添加了大规模稀疏矩阵特征值并行求解功能,提高了程序研究问题的速度以及规模。通过计算内扭曲模(m=1,n=1)和电阻撕裂模(m=2,n=1)的线性增长率和模结构验证了并行及拓展后的程序的可靠性。此外,通过与初始版本的运行结果进行比较,展示了优化后的程序在运行速度、运行规模上的巨大优势,以及程序在研究复杂的磁流体动力学(magnetohydrodynamic,MHD)特征值问题的潜力。
