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
At the late stage of solidification with ultrasonic treatment （UST） in Al-Si alloys, a part of semisolid overflows and climbs along the probe. The interesting phenomenon and its influence on the solidification micro...At the late stage of solidification with ultrasonic treatment （UST） in Al-Si alloys, a part of semisolid overflows and climbs along the probe. The interesting phenomenon and its influence on the solidification microstructure were investigated in order to better study the mechanism of UST. It is considered that the overflowing phenomenon occurs due to the changes of vibration and flow in the remaining semisolid. Because the overflowed portion comes from the region with intense UST effect and vibrates with the probe during solidification, great modification of primary and euteetic Si （about 10 pm in length） and refinement of primary a（Al） （about 70 μm in size） are observed in this portion.展开更多
The time evolution of system in two photon Jaynes Cummings (J C) model without rotating waves approximation (RWA) is obtained by using the theory of ordinary differential equations. Based on the evolution, the mean ...The time evolution of system in two photon Jaynes Cummings (J C) model without rotating waves approximation (RWA) is obtained by using the theory of ordinary differential equations. Based on the evolution, the mean value of the atom inversion operator 〈 S 3(t)〉 is gi ven. The influence of the “counter rotating term” on the collapse and revival phenomenon is discussed from the comparison between the cases with RWA and without RWA. It shows that the influence of the virtual photon field makes the quantum fluctuations appear on the collapse and revival phenomenon.展开更多
Dynamic modeling of a hose-drogue aerial refueling system（HDARS） and an integral sliding mode backstepping controller design for the hose whipping phenomenon（HWP） during probe-drogue coupling are studied. Firstly,...Dynamic modeling of a hose-drogue aerial refueling system（HDARS） and an integral sliding mode backstepping controller design for the hose whipping phenomenon（HWP） during probe-drogue coupling are studied. Firstly, a dynamic model of the variable-length hose-drogue assembly is built for the sake of exploiting suppression methods for the whipping phenomenon.Based on the lumped parameter method, the hose is modeled by a series of variable-length links connected with frictionless joints. A set of iterative equations of the hose＇s three-dimensional motion is derived subject to hose reeling in/out, tanker motion, gravity, and aerodynamic loads accounting for the effects of steady wind, atmospheric turbulence, and tanker wake. Secondly,relying on a permanent magnet synchronous motor and high-precision position sensors, a new active control strategy for the HWP on the basis of the relative position between the tanker and the receiver is proposed. Considering the strict-feedback configuration of the permanent magnet synchronous motor, a rotor position control law based on the backstepping method is designed to insure global stability. An integral of the rotor position error and an exponential sliding mode reaching law of the current errors are applied to enhance control accuracy and robustness. Finally,the simulation results show the effectiveness of the proposed model and control laws.展开更多
The Pearl River Mouth Basin （PRMB） covers an area of approximately 20× 104 km2.However,oil-gas fields detected in this area thus far are highly concentrated and controlled predominantly by second-order structur...The Pearl River Mouth Basin （PRMB） covers an area of approximately 20× 104 km2.However,oil-gas fields detected in this area thus far are highly concentrated and controlled predominantly by second-order structural belts,the seven largest of which aggregate proved oil reserves of 7.7× 108 m3,accounting for 86％ of the total discovered reserve in the basin.These second-order structures have one common phenomenon：oil is contained in all traps present in them.In other words,they are all belt-wide petroliferous reservoirs.Research has identified eight types of second-order structural belts under two categories in the eastern PRMB.Their petroliferous properties are subject to three typical constraints：petroliferous properties of subsags hosting these structural belts,locations of these belts in the petroleum system,and availability of traps prior to the hydrocarbon expulsion and migration.The formation and distribution of oil reservoirs in these belts are characterized by subsag-belt integration and ＂three-in-one＂.The former indicates that sags and the second-order structural belts within the supply range of the sags constitute the basic units of hydrocarbon accumulations and are therefore inseparable.The latter indicates that a belt-wide petroliferous second-order structural belt always contains three important elements：hydrocarbon richness,effective pathway and pre-existing traps.展开更多
A class of E1 Niйo atmospheric physics oscillation model is considered. The E1 Niйo atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions. The conce...A class of E1 Niйo atmospheric physics oscillation model is considered. The E1 Niйo atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions. The conceptual oscillator model should consider the variations of both the eastern and western Pacific anomaly patterns. An E1 Niйo atmospheric physics model is proposed using a method for the variational iteration theory. Using the variational iteration method, the approximate expansions of the solution of corresponding problem are constructed. That is, firstly, introducing a set of functional and accounting their variationals, the Lagrange multiplicators are counted, and then the variational iteration is defined, finally, the approximate solution is obtained. From approximate expansions of the solution, the zonal sea surface temperature anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the sea-air oscillation for E1 Niйo atmospheric physics model can be analyzed. E1 Niйo is a very complicated natural phenomenon. Hence basic models need to be reduced for the sea-air oscillator and are solved. The variational iteration is a simple and valid approximate method.展开更多
A yield phenomenon was firstly reported in an extruded Mg-6.8Y-2.5Cu alloy and the corresponding microstructure was also investigated in this work,The cast alloy is mainly composed ofα-Mg,18R long period stacking ord...A yield phenomenon was firstly reported in an extruded Mg-6.8Y-2.5Cu alloy and the corresponding microstructure was also investigated in this work,The cast alloy is mainly composed ofα-Mg,18R long period stacking order(LPSO)phase,eutectic phase(Mg_(20)Cu_(4)Y_(1)),and Mg_(2)Cu phase.The 18R LPSO phase at the dendritic grain boundary transforms into the 14H LPSO phase in the grain interior during homogenization.After extrusion,the grain size of the homogenized alloy is remarkably refined to-3.69μm and the second phase is significantly broken and distributed in the extrusion direction.Tensile testing curves of the extrude alloy at room temperature indicate that the yield strength and ultimate tensile strength increase while the elongation of the alloy decreases with increasing strain rate.Interestingly,a yield plateau fo rms and gradually decreases with increasing strain rate.The yield phenomenon is related to the dislocation multiplication and the interaction between the movable dislocations and solute atoms.展开更多
The fluid flow and the interfacial phenomenon of slag and metal in tundish with gas blowing were studied with mathematical and physical modeling, and the effects of gas flowrate, the placement of porous beam for the g...The fluid flow and the interfacial phenomenon of slag and metal in tundish with gas blowing were studied with mathematical and physical modeling, and the effects of gas flowrate, the placement of porous beam for the generation of bubbles, and the combination of flow control devices on the flow and slag-metal interface were investigated. The results show that the position of gas bubbling has a significant effect on the flow in tundish, and the placement of porous beam and gas flowrate are the two main factors affecting the entrapment of slag in tundish. The closer the porous beam to the weir, the more reasonable is the flow, which is in favor of the control of slag entrapment in tundish.展开更多
The relatedness between catalytic effect of activated carbon and passivation phenomenon during chalcopyrite bioleachingby mixed thermophilic Archaea culture(Acidianus brierleyi,Metallosphaera sedula,Acidianus manzaens...The relatedness between catalytic effect of activated carbon and passivation phenomenon during chalcopyrite bioleachingby mixed thermophilic Archaea culture(Acidianus brierleyi,Metallosphaera sedula,Acidianus manzaensis and Sulfolobusmetallicus)at65°C was studied.Leaching experiments showed that the addition of activated carbon could significantly promote thedissolution of chalcopyrite for both bioleaching and chemical leaching.The results of synchrotron-based X-ray diffraction,ironL-edge and sulfur K-edge X-ray absorption near edge structure spectroscopy indicated that activated carbon could change thetransition path of electrons through galvanic interactions to form more readily dissolved secondary mineral chalcocite at a low redoxpotential(?400mV)and then enhanced the copper dissolution.Jarosite accumulated immediately in the initial stage of bioleachingwith activated carbon but copper dissolution was not hindered.However,much jarosite precipitated on the surface of chalcopyrite inthe late stage of bioleaching,which might account for the decrease of copper dissolution rate.More elemental sulfur(S0)was alsodetected with additional activated carbon but the mixed thermophilic Archaea culture had a great sulfur oxidation activity,thus S0waseliminated and seemed to have no significant influence on the dissolution of chalcopyrite.展开更多
The fluid motion in partially filled tanks with internal baffles has wide engineering applications. The installation of baffles is expected to reduce the effect of sloshing as well as the consequent environmental dama...The fluid motion in partially filled tanks with internal baffles has wide engineering applications. The installation of baffles is expected to reduce the effect of sloshing as well as the consequent environmental damages. In the present study, a series of experimental tests are performed to investigate the sloshing phenomenon in a baffled rectangular storage tank. In addition, the sloshing phenomenon is also modeled by using Open Foam. Based on the experimental and numerical studies, optimization of the geometric parameters of the tank is performed based on some criteria such as tank area, entropy generation, and the horizontal force exerted on the tank area due to the sloshing phenomenon.The optimization is also carried out based on the entropy generation minimization analysis. It is noted that the optimum baffle height is in the range of h_b/h_w=0.5-0.75 in the present study(where h_b and h_w are the baffle height and water depth, respectively). Based on the results, the optimal design of the tank is achieved with R_A= 0.9-1.0(where R_A=L/W, L and W are the length and width of the tank, respectively). The results also show that the increase of h_b can lead to a decrease of the maximum pressure and horizontal force exerted on the tank. It is also noted that the horizontal force exerted on the tank firstly continues to increase as the sway motion amplitude increases.However, as the normalized motion amplitude parameter, a/L(The parameter a is the motion amplitude), exceeds0.067, the effect of motion amplitude on the force is not obvious. The same optimization is also performed in the multiple-variable-baffled tank and prismatic storage tank.展开更多
PEGylated liposomes are potential candidates to improve the pharmacokinetic characteristics of encapsulated drugs, to extend their circulation half-life and facilitate their passive accumulation at tumour sites. Howev...PEGylated liposomes are potential candidates to improve the pharmacokinetic characteristics of encapsulated drugs, to extend their circulation half-life and facilitate their passive accumulation at tumour sites. However, PEG-modified liposomes can induce accelerated blood clearance(ABC) upon repeated administration, and the extent of ABC phenomenon on the cytotoxic drugs-containing PEGylated liposomes is related to the dose of the cytotoxic drugs.In this study, EPI served as a model cytotoxic drug, a hydrophilic surfactant molecule,monosialylganglioside(GM1) was chosen and modified on the liposomes together with PEG.It was shown that upon mixed modification, when GM1 contents reached 10% or 15% mol,the ABC phenomenon of the PEGylated liposomal EPI significantly reduced. We also found that GM1 played an important role in abrogating the ABC phenomenon in both the induction phase and the effectuation phase. The results suggested that GM1 incorporation unfortunately did not avoid occurrence of ABC phenomenon completely, but GM1 modification on PEGylated liposomes may provide a significant improvement in clinical practice of PEGylated liposomes. Further study must be necessary.展开更多
As for aerospace electromagnetic relay （AEMR） which is of small batches and having difficulty in automatic production, the uncertainty phenomenon is remarkable due to excessive manual work involved in the assembly a...As for aerospace electromagnetic relay （AEMR） which is of small batches and having difficulty in automatic production, the uncertainty phenomenon is remarkable due to excessive manual work involved in the assembly and adjustment processes. This kind of uncertainty may increase the coil voltage difference （CVD） caused by hesitate phenomenon in the pick up process of AEMR. Taking a certain type of AEMR for example, the CVD problem in the actual producing process has been studied in this paper. The primary cause of this issue, two-steps of armature motion （namely hesitate phenomenon） in the pick up process, has been found by analyzing the matching characteristics of electromagnetic and mechanical torques of AEMR. Through the optimization of the matching characteristics, the two-steps of armature motion problem is solved by robust design of the return reed which is a key part of AEMR. The validity of this research has been proved by the comparison of characteristics of AMER before and after the optimization.展开更多
The asymmetric separation has a crucial effect on the performance of the scramjet.In this study,the asymmetric separation and combustion in both rectangular and circular scramjets are investigated numerically,and the ...The asymmetric separation has a crucial effect on the performance of the scramjet.In this study,the asymmetric separation and combustion in both rectangular and circular scramjets are investigated numerically,and the effect of injection scheme is analyzed.The characteristics of the flow field are analyzed based on sufficient code verification.In the rectangular scramjet,the separation tends to occur in the corner due to the corner boundary-layer effect.The separation is asym-metric and only two corners have serious separation.The fuel penetration depth in the separation zone increases and the combustion is intensified.When the injection scheme is uniform,both the combustion and separation become weak.In the circular scramjet,the separation and combustion are basically axisymmetric in the scramjet with one-row injection scheme.The asymmetric combustion becomes obvious in cases with multi-row injection scheme.When the injection orifices distribute intensively on the top and bottom sides,the strongest and weakest separations occur near these two sides respectively.When the distribution of orifices becomes uniform,the direction of separation cannot be predicted.For multi-row cases,the nonuniform injection scheme could result in violent combustion and asymmetric flow structures compared with the uniform injection scheme.展开更多
Specimens of two different kinds of bake hardening steels （BH-Mn and BH-P） were prepared and treated with different annealing processes （water quenching and overaging）. A novel technique of three dimensional atom ...Specimens of two different kinds of bake hardening steels （BH-Mn and BH-P） were prepared and treated with different annealing processes （water quenching and overaging）. A novel technique of three dimensional atom probe was used to investigate solute distributions in these steels. The results indicate that C concentration decreases, whereas V increases during overaging in both bake hardening steels. The conclusion that no vanadium carbides pre- cipitate during the overaging is therefore originally obtained by microanalysis in bake hardening steels. Moreover, bake hardening values of all the specimens were tested by tensile experiments with 2 0/~ pre-deformation. However, those of overaged specimens were further measured with higher levels of pre-deformation because no bake hardening phenomenon was present at 2% pre-deformation. As the pre-deformation increases from 2% to 6% and 8%, both overaged steels show bake hardening values, and the value data are almost the same.展开更多
Researchers reported that intravenously injected PEGylated colloidal drug carriers lose their long-circulating characteristic and accumulated extensively in liver when they are administrated twice in the same animal w...Researchers reported that intravenously injected PEGylated colloidal drug carriers lose their long-circulating characteristic and accumulated extensively in liver when they are administrated twice in the same animal with certain intervals. This phenomenon was referred to as the 'accelerated blood clearance(ABC) phenomenon'. Some former studies had found that complement-mediated phagocytosis, activated by antigen–antibody complex, was responsible for inducing the phenomenon. According to the theory, we have used cobra venom factor to deplete complement in vivo and to investigate the effect of complement inhibition on the ABC phenomenon. Rats were administered by injection of cobra venom factor solution to build up the model of complement exhaustion/inhibition, and the effect of the inhibition of complement on ABC phenomenon was carried out. It seemed that inhibition of complement didn’t affect the pharmacokinetic of the first infection. By contrast, in rats of which complement had been depleted, the second dose of PEGylated nanoemulsions showed enhanced circulation time compared with normal rats in a complement inhibition-independent manner, but the ABC phenomenon was not completely eliminated. It indicated that complement inhibition could certainly weaken the accelerated clearance;meanwhile, there were other factors causing the ABC effect.These findings provide novel insights into the attenuating of ABC phenomenon and lay foundation for further study of immune mechanism.展开更多
Zonal disintegration is a typical static phenomenon of deep rock masses. It has been defined as alternating regions of fractured and relatively intact rock mass that appear around or in front of the working stope duri...Zonal disintegration is a typical static phenomenon of deep rock masses. It has been defined as alternating regions of fractured and relatively intact rock mass that appear around or in front of the working stope during excavation of a deep tunnel. Zonal disintegration phenomenon was successfully demonstrated in the laboratory with 3D tests on analogous gypsum models, two circular cracked zones were observed in the test. The linear Mohr-Coulomb yield criterion was used with a constitutive model that showed linear softening and ideal residual plastic to analyze the elasto-plastic field of the enclosing rock mass around a deep tunnel. The results show that tunneling causes a maximum stress zone to appear between an elastic and plastic zone in the surrounding rock. The zonal disintegration phenomenon is analyzed by considering the stress-strain state of the rock mass in the vicinity of the maximum stress zone. Creep instability failure of the rock due to the development of the plastic zone, and transfer of the maximum stress zone into the rock mass, are the cause of zonal disintegration. An analytical criterion for the critical depth at which zonal disintegration can occur is derived. This depth depends mainly on the character and stress concentration coefficient of the rock mass.展开更多
The Lie group method is applied to present an analysis of the magneto hydro-dynamics（MHD） steady laminar flow and the heat transfer from a warm laminar liquid flow to a melting moving surface in the presence of ther...The Lie group method is applied to present an analysis of the magneto hydro-dynamics（MHD） steady laminar flow and the heat transfer from a warm laminar liquid flow to a melting moving surface in the presence of thermal radiation.By using the Lie group method,we have presented the transformation groups for the problem apart from the scaling group.The application of this method reduces the partial differential equations（PDEs） with their boundary conditions governing the flow and heat transfer to a system of nonlinear ordinary differential equations（ODEs） with appropriate boundary conditions.The resulting nonlinear system of ODEs is solved numerically using the implicit finite difference method（FDM）.The local skin-friction coefficients and the local Nusselt numbers for different physical parameters are presented in a table.展开更多
Quantum correlation shows a fascinating nature of quantum mechanics and plays an important role in some physics topics,especially in the field of quantum information.Quantum correlations of the composite system can be...Quantum correlation shows a fascinating nature of quantum mechanics and plays an important role in some physics topics,especially in the field of quantum information.Quantum correlations of the composite system can be quantified by resorting to geometric or entropy methods,and all these quantification methods exhibit the peculiar freezing phenomenon.The challenge is to find the characteristics of the quantum states that generate the freezing phenomenon,rather than only study the conditions which generate this phenomenon under a certain quantum system.In essence,this is a classification problem.Machine learning has become an effective method for researchers to study classification and feature generation.In this work,we prove that the machine learning can solve the problem of X form quantum states,which is a problem of physical significance.Subsequently,we apply the density-based spatial clustering of applications with noise(DBSCAN)algorithm and the decision tree to divide quantum states into two different groups.Our goal is to classify the quantum correlations of quantum states into two classes:one is the quantum correlation with freezing phenomenon for both Rènyi discord(α=2)and the geometric discord(Bures distance),the other is the quantum correlation of non-freezing phenomenon.The results demonstrate that the machine learning method has reasonable performance in quantum correlation research.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Project(50874022)supported by the National Natural Science Foundation of China
文摘At the late stage of solidification with ultrasonic treatment （UST） in Al-Si alloys, a part of semisolid overflows and climbs along the probe. The interesting phenomenon and its influence on the solidification microstructure were investigated in order to better study the mechanism of UST. It is considered that the overflowing phenomenon occurs due to the changes of vibration and flow in the remaining semisolid. Because the overflowed portion comes from the region with intense UST effect and vibrates with the probe during solidification, great modification of primary and euteetic Si （about 10 pm in length） and refinement of primary a（Al） （about 70 μm in size） are observed in this portion.
文摘The time evolution of system in two photon Jaynes Cummings (J C) model without rotating waves approximation (RWA) is obtained by using the theory of ordinary differential equations. Based on the evolution, the mean value of the atom inversion operator 〈 S 3(t)〉 is gi ven. The influence of the “counter rotating term” on the collapse and revival phenomenon is discussed from the comparison between the cases with RWA and without RWA. It shows that the influence of the virtual photon field makes the quantum fluctuations appear on the collapse and revival phenomenon.
基金supported by the National Natural Science Foundation of China(No.61304120)
文摘Dynamic modeling of a hose-drogue aerial refueling system（HDARS） and an integral sliding mode backstepping controller design for the hose whipping phenomenon（HWP） during probe-drogue coupling are studied. Firstly, a dynamic model of the variable-length hose-drogue assembly is built for the sake of exploiting suppression methods for the whipping phenomenon.Based on the lumped parameter method, the hose is modeled by a series of variable-length links connected with frictionless joints. A set of iterative equations of the hose＇s three-dimensional motion is derived subject to hose reeling in/out, tanker motion, gravity, and aerodynamic loads accounting for the effects of steady wind, atmospheric turbulence, and tanker wake. Secondly,relying on a permanent magnet synchronous motor and high-precision position sensors, a new active control strategy for the HWP on the basis of the relative position between the tanker and the receiver is proposed. Considering the strict-feedback configuration of the permanent magnet synchronous motor, a rotor position control law based on the backstepping method is designed to insure global stability. An integral of the rotor position error and an exponential sliding mode reaching law of the current errors are applied to enhance control accuracy and robustness. Finally,the simulation results show the effectiveness of the proposed model and control laws.
文摘The Pearl River Mouth Basin （PRMB） covers an area of approximately 20× 104 km2.However,oil-gas fields detected in this area thus far are highly concentrated and controlled predominantly by second-order structural belts,the seven largest of which aggregate proved oil reserves of 7.7× 108 m3,accounting for 86％ of the total discovered reserve in the basin.These second-order structures have one common phenomenon：oil is contained in all traps present in them.In other words,they are all belt-wide petroliferous reservoirs.Research has identified eight types of second-order structural belts under two categories in the eastern PRMB.Their petroliferous properties are subject to three typical constraints：petroliferous properties of subsags hosting these structural belts,locations of these belts in the petroleum system,and availability of traps prior to the hydrocarbon expulsion and migration.The formation and distribution of oil reservoirs in these belts are characterized by subsag-belt integration and ＂three-in-one＂.The former indicates that sags and the second-order structural belts within the supply range of the sags constitute the basic units of hydrocarbon accumulations and are therefore inseparable.The latter indicates that a belt-wide petroliferous second-order structural belt always contains three important elements：hydrocarbon richness,effective pathway and pre-existing traps.
文摘A class of E1 Niйo atmospheric physics oscillation model is considered. The E1 Niйo atmospheric physics oscillation is an abnormal phenomenon involved in the tropical Pacific ocean-atmosphere interactions. The conceptual oscillator model should consider the variations of both the eastern and western Pacific anomaly patterns. An E1 Niйo atmospheric physics model is proposed using a method for the variational iteration theory. Using the variational iteration method, the approximate expansions of the solution of corresponding problem are constructed. That is, firstly, introducing a set of functional and accounting their variationals, the Lagrange multiplicators are counted, and then the variational iteration is defined, finally, the approximate solution is obtained. From approximate expansions of the solution, the zonal sea surface temperature anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the sea-air oscillation for E1 Niйo atmospheric physics model can be analyzed. E1 Niйo is a very complicated natural phenomenon. Hence basic models need to be reduced for the sea-air oscillator and are solved. The variational iteration is a simple and valid approximate method.
基金Project supported by the National Natural Science Foundation of China(51961021,52001152 and 51901174)China Postdoctoral Science Foundation(2020M673383)。
文摘A yield phenomenon was firstly reported in an extruded Mg-6.8Y-2.5Cu alloy and the corresponding microstructure was also investigated in this work,The cast alloy is mainly composed ofα-Mg,18R long period stacking order(LPSO)phase,eutectic phase(Mg_(20)Cu_(4)Y_(1)),and Mg_(2)Cu phase.The 18R LPSO phase at the dendritic grain boundary transforms into the 14H LPSO phase in the grain interior during homogenization.After extrusion,the grain size of the homogenized alloy is remarkably refined to-3.69μm and the second phase is significantly broken and distributed in the extrusion direction.Tensile testing curves of the extrude alloy at room temperature indicate that the yield strength and ultimate tensile strength increase while the elongation of the alloy decreases with increasing strain rate.Interestingly,a yield plateau fo rms and gradually decreases with increasing strain rate.The yield phenomenon is related to the dislocation multiplication and the interaction between the movable dislocations and solute atoms.
基金Item Sponsored by National Natural Science Foundation of China (50674020)Program for New Century Excellent Talents in University (NCET-04-0285)
文摘The fluid flow and the interfacial phenomenon of slag and metal in tundish with gas blowing were studied with mathematical and physical modeling, and the effects of gas flowrate, the placement of porous beam for the generation of bubbles, and the combination of flow control devices on the flow and slag-metal interface were investigated. The results show that the position of gas bubbling has a significant effect on the flow in tundish, and the placement of porous beam and gas flowrate are the two main factors affecting the entrapment of slag in tundish. The closer the porous beam to the weir, the more reasonable is the flow, which is in favor of the control of slag entrapment in tundish.
基金Project(51274257) supported by the National Natural Science Foundation of ChinaProject(U1232103) supported by the Joint Funds of National Natural Science Foundation of China and Large Scientific Facility Foundation of Chinese Academy of Sciences+1 种基金Project(VR-12419) supported by the Beijing Synchrotron Radiation Facility Public User Program,ChinaProject(15ssrf00924) supported by the Shanghai Institute of Applied Physics Open Fund of Shanghai Synchrotron Radiation Facility,China
文摘The relatedness between catalytic effect of activated carbon and passivation phenomenon during chalcopyrite bioleachingby mixed thermophilic Archaea culture(Acidianus brierleyi,Metallosphaera sedula,Acidianus manzaensis and Sulfolobusmetallicus)at65°C was studied.Leaching experiments showed that the addition of activated carbon could significantly promote thedissolution of chalcopyrite for both bioleaching and chemical leaching.The results of synchrotron-based X-ray diffraction,ironL-edge and sulfur K-edge X-ray absorption near edge structure spectroscopy indicated that activated carbon could change thetransition path of electrons through galvanic interactions to form more readily dissolved secondary mineral chalcocite at a low redoxpotential(?400mV)and then enhanced the copper dissolution.Jarosite accumulated immediately in the initial stage of bioleachingwith activated carbon but copper dissolution was not hindered.However,much jarosite precipitated on the surface of chalcopyrite inthe late stage of bioleaching,which might account for the decrease of copper dissolution rate.More elemental sulfur(S0)was alsodetected with additional activated carbon but the mixed thermophilic Archaea culture had a great sulfur oxidation activity,thus S0waseliminated and seemed to have no significant influence on the dissolution of chalcopyrite.
基金inancially supported by the National Natural Science Foundation of China (Grant No. 51761135011)Joint supported by NSFC and Royal Society (Grant No. 52011530183)。
文摘The fluid motion in partially filled tanks with internal baffles has wide engineering applications. The installation of baffles is expected to reduce the effect of sloshing as well as the consequent environmental damages. In the present study, a series of experimental tests are performed to investigate the sloshing phenomenon in a baffled rectangular storage tank. In addition, the sloshing phenomenon is also modeled by using Open Foam. Based on the experimental and numerical studies, optimization of the geometric parameters of the tank is performed based on some criteria such as tank area, entropy generation, and the horizontal force exerted on the tank area due to the sloshing phenomenon.The optimization is also carried out based on the entropy generation minimization analysis. It is noted that the optimum baffle height is in the range of h_b/h_w=0.5-0.75 in the present study(where h_b and h_w are the baffle height and water depth, respectively). Based on the results, the optimal design of the tank is achieved with R_A= 0.9-1.0(where R_A=L/W, L and W are the length and width of the tank, respectively). The results also show that the increase of h_b can lead to a decrease of the maximum pressure and horizontal force exerted on the tank. It is also noted that the horizontal force exerted on the tank firstly continues to increase as the sway motion amplitude increases.However, as the normalized motion amplitude parameter, a/L(The parameter a is the motion amplitude), exceeds0.067, the effect of motion amplitude on the force is not obvious. The same optimization is also performed in the multiple-variable-baffled tank and prismatic storage tank.
基金supported by the National Natural Science Foundation of China (Grant No.81373334)
文摘PEGylated liposomes are potential candidates to improve the pharmacokinetic characteristics of encapsulated drugs, to extend their circulation half-life and facilitate their passive accumulation at tumour sites. However, PEG-modified liposomes can induce accelerated blood clearance(ABC) upon repeated administration, and the extent of ABC phenomenon on the cytotoxic drugs-containing PEGylated liposomes is related to the dose of the cytotoxic drugs.In this study, EPI served as a model cytotoxic drug, a hydrophilic surfactant molecule,monosialylganglioside(GM1) was chosen and modified on the liposomes together with PEG.It was shown that upon mixed modification, when GM1 contents reached 10% or 15% mol,the ABC phenomenon of the PEGylated liposomal EPI significantly reduced. We also found that GM1 played an important role in abrogating the ABC phenomenon in both the induction phase and the effectuation phase. The results suggested that GM1 incorporation unfortunately did not avoid occurrence of ABC phenomenon completely, but GM1 modification on PEGylated liposomes may provide a significant improvement in clinical practice of PEGylated liposomes. Further study must be necessary.
基金the National Natural Science Foundation of China(No.51107012)the National High-tech Research and Development Program of China(No.2009AA04Z110)+1 种基金the China Postdoctoral Science Foundation(No.2011M500057)the Fundamental Research Funds for the Central Universities(No.HIT.NSRIF.2010099)
文摘As for aerospace electromagnetic relay （AEMR） which is of small batches and having difficulty in automatic production, the uncertainty phenomenon is remarkable due to excessive manual work involved in the assembly and adjustment processes. This kind of uncertainty may increase the coil voltage difference （CVD） caused by hesitate phenomenon in the pick up process of AEMR. Taking a certain type of AEMR for example, the CVD problem in the actual producing process has been studied in this paper. The primary cause of this issue, two-steps of armature motion （namely hesitate phenomenon） in the pick up process, has been found by analyzing the matching characteristics of electromagnetic and mechanical torques of AEMR. Through the optimization of the matching characteristics, the two-steps of armature motion problem is solved by robust design of the return reed which is a key part of AEMR. The validity of this research has been proved by the comparison of characteristics of AMER before and after the optimization.
基金supported by the National Natural Science Foundation of China(Nos.11925207,12002381)the Scientific Research Plan of National University of Defense Technology in 2019,China(No.ZK19-02)+1 种基金the Postgraduate Scientific Research Innovation Project of Hunan Province,China(No.CX20200084)the Equipment Pre-research Foundation of Key Laboratory,China(No.6142703200311)。
文摘The asymmetric separation has a crucial effect on the performance of the scramjet.In this study,the asymmetric separation and combustion in both rectangular and circular scramjets are investigated numerically,and the effect of injection scheme is analyzed.The characteristics of the flow field are analyzed based on sufficient code verification.In the rectangular scramjet,the separation tends to occur in the corner due to the corner boundary-layer effect.The separation is asym-metric and only two corners have serious separation.The fuel penetration depth in the separation zone increases and the combustion is intensified.When the injection scheme is uniform,both the combustion and separation become weak.In the circular scramjet,the separation and combustion are basically axisymmetric in the scramjet with one-row injection scheme.The asymmetric combustion becomes obvious in cases with multi-row injection scheme.When the injection orifices distribute intensively on the top and bottom sides,the strongest and weakest separations occur near these two sides respectively.When the distribution of orifices becomes uniform,the direction of separation cannot be predicted.For multi-row cases,the nonuniform injection scheme could result in violent combustion and asymmetric flow structures compared with the uniform injection scheme.
基金sponsored by National Natural Science Foundation of China(50934011,50971137)National Basic Research Program of China(2010CB630802)
文摘Specimens of two different kinds of bake hardening steels （BH-Mn and BH-P） were prepared and treated with different annealing processes （water quenching and overaging）. A novel technique of three dimensional atom probe was used to investigate solute distributions in these steels. The results indicate that C concentration decreases, whereas V increases during overaging in both bake hardening steels. The conclusion that no vanadium carbides pre- cipitate during the overaging is therefore originally obtained by microanalysis in bake hardening steels. Moreover, bake hardening values of all the specimens were tested by tensile experiments with 2 0/~ pre-deformation. However, those of overaged specimens were further measured with higher levels of pre-deformation because no bake hardening phenomenon was present at 2% pre-deformation. As the pre-deformation increases from 2% to 6% and 8%, both overaged steels show bake hardening values, and the value data are almost the same.
基金supported by the National Natural Science Foundation of China(Grant No.81373334)
文摘Researchers reported that intravenously injected PEGylated colloidal drug carriers lose their long-circulating characteristic and accumulated extensively in liver when they are administrated twice in the same animal with certain intervals. This phenomenon was referred to as the 'accelerated blood clearance(ABC) phenomenon'. Some former studies had found that complement-mediated phagocytosis, activated by antigen–antibody complex, was responsible for inducing the phenomenon. According to the theory, we have used cobra venom factor to deplete complement in vivo and to investigate the effect of complement inhibition on the ABC phenomenon. Rats were administered by injection of cobra venom factor solution to build up the model of complement exhaustion/inhibition, and the effect of the inhibition of complement on ABC phenomenon was carried out. It seemed that inhibition of complement didn’t affect the pharmacokinetic of the first infection. By contrast, in rats of which complement had been depleted, the second dose of PEGylated nanoemulsions showed enhanced circulation time compared with normal rats in a complement inhibition-independent manner, but the ABC phenomenon was not completely eliminated. It indicated that complement inhibition could certainly weaken the accelerated clearance;meanwhile, there were other factors causing the ABC effect.These findings provide novel insights into the attenuating of ABC phenomenon and lay foundation for further study of immune mechanism.
基金Projects 50490275 and 50525825 supported by the National Natural Science Foundation of China
文摘Zonal disintegration is a typical static phenomenon of deep rock masses. It has been defined as alternating regions of fractured and relatively intact rock mass that appear around or in front of the working stope during excavation of a deep tunnel. Zonal disintegration phenomenon was successfully demonstrated in the laboratory with 3D tests on analogous gypsum models, two circular cracked zones were observed in the test. The linear Mohr-Coulomb yield criterion was used with a constitutive model that showed linear softening and ideal residual plastic to analyze the elasto-plastic field of the enclosing rock mass around a deep tunnel. The results show that tunneling causes a maximum stress zone to appear between an elastic and plastic zone in the surrounding rock. The zonal disintegration phenomenon is analyzed by considering the stress-strain state of the rock mass in the vicinity of the maximum stress zone. Creep instability failure of the rock due to the development of the plastic zone, and transfer of the maximum stress zone into the rock mass, are the cause of zonal disintegration. An analytical criterion for the critical depth at which zonal disintegration can occur is derived. This depth depends mainly on the character and stress concentration coefficient of the rock mass.
文摘The Lie group method is applied to present an analysis of the magneto hydro-dynamics（MHD） steady laminar flow and the heat transfer from a warm laminar liquid flow to a melting moving surface in the presence of thermal radiation.By using the Lie group method,we have presented the transformation groups for the problem apart from the scaling group.The application of this method reduces the partial differential equations（PDEs） with their boundary conditions governing the flow and heat transfer to a system of nonlinear ordinary differential equations（ODEs） with appropriate boundary conditions.The resulting nonlinear system of ODEs is solved numerically using the implicit finite difference method（FDM）.The local skin-friction coefficients and the local Nusselt numbers for different physical parameters are presented in a table.
基金supported by the National Natural Science Foundation of China(61502082)National Key R&D Program of China,Grant No.(2018YFA0306703).
文摘Quantum correlation shows a fascinating nature of quantum mechanics and plays an important role in some physics topics,especially in the field of quantum information.Quantum correlations of the composite system can be quantified by resorting to geometric or entropy methods,and all these quantification methods exhibit the peculiar freezing phenomenon.The challenge is to find the characteristics of the quantum states that generate the freezing phenomenon,rather than only study the conditions which generate this phenomenon under a certain quantum system.In essence,this is a classification problem.Machine learning has become an effective method for researchers to study classification and feature generation.In this work,we prove that the machine learning can solve the problem of X form quantum states,which is a problem of physical significance.Subsequently,we apply the density-based spatial clustering of applications with noise(DBSCAN)algorithm and the decision tree to divide quantum states into two different groups.Our goal is to classify the quantum correlations of quantum states into two classes:one is the quantum correlation with freezing phenomenon for both Rènyi discord(α=2)and the geometric discord(Bures distance),the other is the quantum correlation of non-freezing phenomenon.The results demonstrate that the machine learning method has reasonable performance in quantum correlation research.
