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Effects of surface roughness on nonlinear convective dissipative flow of micropolar nanofluids with dual activation energies and triple diffusion
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作者 Z.Z.RASHED S.E.AHMED 《Applied Mathematics and Mechanics(English Edition)》 2025年第9期1809-1828,共20页
This study explores the complex dynamics of unsteady convective flow in micropolar nanofluids over a rough conical surface, with a focus on the effects of triple diffusive transport and Arrhenius activation energy. Th... This study explores the complex dynamics of unsteady convective flow in micropolar nanofluids over a rough conical surface, with a focus on the effects of triple diffusive transport and Arrhenius activation energy. The primary objective is to understand the interplay among nonlinear convection, micro-rotation effects, and species diffusion under the influence of thermal and electromagnetic forces. The analysis is motivated by practical applications of cryogenic fluids, specifically liquid hydrogen and liquid nitrogen,where precise control of heat and mass transport is critical. The conical surface roughness is mathematically modeled as a high-frequency, small-amplitude sinusoidal waveform.To address the non-similar nature of the boundary-layer equations, Mangler's transformations are employed, followed by the implementation of a finite difference scheme for numerical solutions. The methodology further integrates a machine learning-based neural network to predict the skin friction under the influence of roughness-induced perturbations, ensuring computational efficiency and improved generalization. The study yields several novel findings. Notably, the presence of surface roughness introduces the wavelike modulations in the local skin friction coefficient. It is also observed that nonlinear convective interactions, enhanced by temperature gradients and vortex viscosity parameters, significantly intensify near-wall velocity gradients. Moreover, key physical quantities are correlated with governing parameters using power-law relationships, providing generalized predictive models. The validation of the numerical results is achieved through consistency checks with the existing limiting solutions and convergence analysis, ensuring the reliability of the proposed computational framework. 展开更多
关键词 rough-conical surface micropolar nanoliquid magnetohydrodynamics(MHD) artificial neural network(ANN) finite difierence method(FDM) triple mass difiusion nonlinear convection activation energy
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磁共振扩散峰度成像评价颈椎病脊髓微观结构的变化 被引量:3
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作者 于金芬 郑修竹 李传亭 《中国医学计算机成像杂志》 CSCD 北大核心 2019年第4期343-347,共5页
目的:探讨磁共振扩散峰度成像评价脊髓型颈椎病脊髓微观结构变化的可行性及量化特征。方法:本研究选择了29名脊髓型颈椎病患者。所有图像均在3.0T MR扫描仪上获得。釆用T2WI及DKI矢状位融合图像,分别于病变处脊髓、邻近病变的脊髓和正... 目的:探讨磁共振扩散峰度成像评价脊髓型颈椎病脊髓微观结构变化的可行性及量化特征。方法:本研究选择了29名脊髓型颈椎病患者。所有图像均在3.0T MR扫描仪上获得。釆用T2WI及DKI矢状位融合图像,分别于病变处脊髓、邻近病变的脊髓和正常脊髓三个不同水平设定感兴趣区域(ROI)测量各向异性分数(FA)值、表观弥散系数(ADC)值和平均扩散峰度(MK)值并两两比较。结果:所有患者邻近病变颈髓的MK值明显低于正常颈髓(0.862±0.51 vs.0.976±0.0924,P<0.0001),但FA和ADC值无统计学差异(P>0.05)。病变的颈髓MK(0.716±0.0753)和FA值低于正常颈髓,ADC(P<0.001)值高于正常颈髓。结论:脊髓型颈椎病的磁共振扩散加权成像是可行的,MK能够反映颈髓损伤的微观结构变化,并且可能获得比扩散成像更多的信息。 展开更多
关键词 磁共振成像 扩散峰度成像 平均峰度 脊髓型颈椎病
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