Mechanical properties of Mg-3Gd(wt.%)samples with average grain sizes ranging from 3 to 45μm were characterized by room temperature tensile test.A reversal of the trade-off,i.e.,high yield strength and large tensile ...Mechanical properties of Mg-3Gd(wt.%)samples with average grain sizes ranging from 3 to 45μm were characterized by room temperature tensile test.A reversal of the trade-off,i.e.,high yield strength and large tensile elongation,was simultaneously observed in the fine-grained samples.The microstructures and hardening response were analyzed in terms of the viewpoint of strain evolution,including local strain evolution by tensile digital image correlation strain measurement,and lattice strain by using synchrotronbased in-situ high energy X-ray diffraction technique.The dislocation-based deformation mechanisms were investigated to underpin the microstructural origin of the yield point phenomenon and enhancement in work-hardening.The occurrence of the yield point phenomenon represented by a yield drop and propagation of the Lüders band is related to the absence of mobile dislocations at an early stage and to the slip transmission between the adjacent grain.The extraordinary work-hardening enhancement over an extended range can be ascribed mainly to the increases in dislocation multiplication and accumulation capabilities by the activation and interaction of multiple slip systems includingand<c+a>types.These results contribute to the design of strong and ductile Mg alloys.展开更多
BACKGROUND Splenic artery aneurysm(SAA)rupture is a rare,life-threatening condition characterized by acute intra-abdominal hemorrhage and hemodynamic instability.Ruptured SAAs may exhibit a biphasic and relatively slo...BACKGROUND Splenic artery aneurysm(SAA)rupture is a rare,life-threatening condition characterized by acute intra-abdominal hemorrhage and hemodynamic instability.Ruptured SAAs may exhibit a biphasic and relatively slow clinical progression,commonly referred to as the“double-rupture phenomenon”.The reported incidence of the double-rupture phenomenon ranges 12%-21%in patients with ruptured SAAs,potentially due to variations in intra-abdominal pressure.Following anesthesia induction,muscle relaxation can decrease intra-abdominal pressure,potentially triggering the double-rupture phenomenon and leading to circulatory collapse.CASE SUMMARY A 61-year-old female presented to the Department of Emergency with upper abdominal pain,abdominal distension,dizziness,and vomiting.Her vital signs were initially stable.Physical examination revealed abdominal tenderness and positive-shifting dullness.Abdominal contrast-enhanced computed tomography revealed cirrhosis,severe portal hypertension,and splenomegaly.Acute rupture was suggested by a hematoma on the upper left side outside the SAA.Surgeons deemed intravascular intervention challenging and open splenectomy inevitable.Circulatory collapse occurred after anesthesia induction,likely due to a double rupture of the SAA.This double-rupture phenomenon may have resulted from an initial rupture of the SAA into the omental bursa,forming a hematoma that exerted a tamponade effect.A second rupture into the peritoneal cavity may have been triggered by decreased intra-abdominal pressure following anesthesia induction.The patient’s life was saved through early,coordinated,multidisciplinary significant postoperative bleeding or hypoxic encephalopathy.CONCLUSION Anesthesia-induced pressure reduction may trigger a second SAA rupture,causing collapse.Early diagnosis and multidisciplinary teamwork improve outcomes.This is a rare and life-threatening case of SAA rupture,which is of great significance to the medical community for understanding and handling such emergencies.展开更多
With the availability of high-performance computing technology and the development of advanced numerical simulation methods, Computational Fluid Dynamics (CFD) is becoming more and more practical and efficient in engi...With the availability of high-performance computing technology and the development of advanced numerical simulation methods, Computational Fluid Dynamics (CFD) is becoming more and more practical and efficient in engineering. As one of the high-precision representative algorithms, the high-order Discontinuous Galerkin Method (DGM) has not only attracted widespread attention from scholars in the CFD research community, but also received strong development. However, when DGM is extended to high-speed aerodynamic flow field calculations, non-physical numerical Gibbs oscillations near shock waves often significantly affect the numerical accuracy and even cause calculation failure. Data driven approaches based on machine learning techniques can be used to learn the characteristics of Gibbs noise, which motivates us to use it in high-speed DG applications. To achieve this goal, labeled data need to be generated in order to train the machine learning models. This paper proposes a new method for denoising modeling of Gibbs phenomenon using a machine learning technique, the zero-shot learning strategy, to eliminate acquiring large amounts of CFD data. The model adopts a graph convolutional network combined with graph attention mechanism to learn the denoising paradigm from synthetic Gibbs noise data and generalize to DGM numerical simulation data. Numerical simulation results show that the Gibbs denoising model proposed in this paper can suppress the numerical oscillation near shock waves in the high-order DGM. Our work automates the extension of DGM to high-speed aerodynamic flow field calculations with higher generalization and lower cost.展开更多
Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typica...Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers,describing the viscous and capillary forces, to quantificationally induce evolution of invasion patterns.While the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial tension.Our research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media.展开更多
The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generali...The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generalized functions and the convergence is weak convergence in the sense of the convergence of continuous linear functionals defining them. The figures show that the approximations of the Fourier series possess oscillations around the function which they represent in a broad band embedding them. This is some analogue to the Gibbs phenomenon. A modification of Fourier series by expansion in powers cosn(x)for the symmetric part of functions and sin(x)cosn−1(x)for the antisymmetric part (analogous to Taylor series) is discussed and illustrated by examples. The Fourier series and their convergence behavior are illustrated also for some 2π-periodic delta-function-like sequences connected with the Poisson theorem showing non-vanishing oscillations around the singularities similar to the Gibbs phenomenon in the neighborhood of discontinuities of functions. .展开更多
基金financially supported by the National Key Research and Develop-ment Program(No.2023YFB3712702)the National Natural Science Foundation of China(Nos.52071038,52071039,and 52301156)the Natural Science Foundation of Jiangsu Province(Nos.BK20232025 and BK20243005)。
文摘Mechanical properties of Mg-3Gd(wt.%)samples with average grain sizes ranging from 3 to 45μm were characterized by room temperature tensile test.A reversal of the trade-off,i.e.,high yield strength and large tensile elongation,was simultaneously observed in the fine-grained samples.The microstructures and hardening response were analyzed in terms of the viewpoint of strain evolution,including local strain evolution by tensile digital image correlation strain measurement,and lattice strain by using synchrotronbased in-situ high energy X-ray diffraction technique.The dislocation-based deformation mechanisms were investigated to underpin the microstructural origin of the yield point phenomenon and enhancement in work-hardening.The occurrence of the yield point phenomenon represented by a yield drop and propagation of the Lüders band is related to the absence of mobile dislocations at an early stage and to the slip transmission between the adjacent grain.The extraordinary work-hardening enhancement over an extended range can be ascribed mainly to the increases in dislocation multiplication and accumulation capabilities by the activation and interaction of multiple slip systems includingand<c+a>types.These results contribute to the design of strong and ductile Mg alloys.
基金Supported by National High Level Hospital Clinical Research Funding,No.2022-PUMCH-B-119.
文摘BACKGROUND Splenic artery aneurysm(SAA)rupture is a rare,life-threatening condition characterized by acute intra-abdominal hemorrhage and hemodynamic instability.Ruptured SAAs may exhibit a biphasic and relatively slow clinical progression,commonly referred to as the“double-rupture phenomenon”.The reported incidence of the double-rupture phenomenon ranges 12%-21%in patients with ruptured SAAs,potentially due to variations in intra-abdominal pressure.Following anesthesia induction,muscle relaxation can decrease intra-abdominal pressure,potentially triggering the double-rupture phenomenon and leading to circulatory collapse.CASE SUMMARY A 61-year-old female presented to the Department of Emergency with upper abdominal pain,abdominal distension,dizziness,and vomiting.Her vital signs were initially stable.Physical examination revealed abdominal tenderness and positive-shifting dullness.Abdominal contrast-enhanced computed tomography revealed cirrhosis,severe portal hypertension,and splenomegaly.Acute rupture was suggested by a hematoma on the upper left side outside the SAA.Surgeons deemed intravascular intervention challenging and open splenectomy inevitable.Circulatory collapse occurred after anesthesia induction,likely due to a double rupture of the SAA.This double-rupture phenomenon may have resulted from an initial rupture of the SAA into the omental bursa,forming a hematoma that exerted a tamponade effect.A second rupture into the peritoneal cavity may have been triggered by decreased intra-abdominal pressure following anesthesia induction.The patient’s life was saved through early,coordinated,multidisciplinary significant postoperative bleeding or hypoxic encephalopathy.CONCLUSION Anesthesia-induced pressure reduction may trigger a second SAA rupture,causing collapse.Early diagnosis and multidisciplinary teamwork improve outcomes.This is a rare and life-threatening case of SAA rupture,which is of great significance to the medical community for understanding and handling such emergencies.
基金co-supported by the Aeronautical Science Foundation of China(Nos.2018ZA52002,2019ZA052011).
文摘With the availability of high-performance computing technology and the development of advanced numerical simulation methods, Computational Fluid Dynamics (CFD) is becoming more and more practical and efficient in engineering. As one of the high-precision representative algorithms, the high-order Discontinuous Galerkin Method (DGM) has not only attracted widespread attention from scholars in the CFD research community, but also received strong development. However, when DGM is extended to high-speed aerodynamic flow field calculations, non-physical numerical Gibbs oscillations near shock waves often significantly affect the numerical accuracy and even cause calculation failure. Data driven approaches based on machine learning techniques can be used to learn the characteristics of Gibbs noise, which motivates us to use it in high-speed DG applications. To achieve this goal, labeled data need to be generated in order to train the machine learning models. This paper proposes a new method for denoising modeling of Gibbs phenomenon using a machine learning technique, the zero-shot learning strategy, to eliminate acquiring large amounts of CFD data. The model adopts a graph convolutional network combined with graph attention mechanism to learn the denoising paradigm from synthetic Gibbs noise data and generalize to DGM numerical simulation data. Numerical simulation results show that the Gibbs denoising model proposed in this paper can suppress the numerical oscillation near shock waves in the high-order DGM. Our work automates the extension of DGM to high-speed aerodynamic flow field calculations with higher generalization and lower cost.
基金supported by the National Natural Science Foundation of China Joint Fund Project (Grant/Award Number: U20B6003)National Natural Science Foundation of China (Grant/Award Number: 52304054)。
文摘Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers,describing the viscous and capillary forces, to quantificationally induce evolution of invasion patterns.While the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial tension.Our research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media.
文摘The Fourier series of the 2π-periodic functions tg(x2)and 1sin(x)and some of their relatives (first of their integrals) are investigated and illustrated with respect to their convergence. These functions are Generalized functions and the convergence is weak convergence in the sense of the convergence of continuous linear functionals defining them. The figures show that the approximations of the Fourier series possess oscillations around the function which they represent in a broad band embedding them. This is some analogue to the Gibbs phenomenon. A modification of Fourier series by expansion in powers cosn(x)for the symmetric part of functions and sin(x)cosn−1(x)for the antisymmetric part (analogous to Taylor series) is discussed and illustrated by examples. The Fourier series and their convergence behavior are illustrated also for some 2π-periodic delta-function-like sequences connected with the Poisson theorem showing non-vanishing oscillations around the singularities similar to the Gibbs phenomenon in the neighborhood of discontinuities of functions. .
