This article is devoted to experimental study on the control of the oblique shock wave around the ramp in a low-temperature supersonic flow by means of the magnetohydrodynamic(MHD)flow control technique.The purpose of...This article is devoted to experimental study on the control of the oblique shock wave around the ramp in a low-temperature supersonic flow by means of the magnetohydrodynamic(MHD)flow control technique.The purpose of the experiments is to take advantage of MHD interaction to weaken the oblique shock wave strength by changing the boundary flow characteristics around the ramp.Plasma columns are generated by pulsed direct current(DC)discharge,the magnetic fields are generated by Nd-Fe-B rare-earth permanent magnets and the oblique shock waves in supersonic flow are generated by the ramp.The Lorentz body force effect of MHD interaction on the plasma-induced airflow velocity is verified through particle image velocimetry(PIV)measurements.The experimental results from the supersonic wind tunnel indicate that the MHD flow control can drastically change the flow characteristics of the airflow around the ramp and decrease the ratio of the Pitot pressure after shock wave to that before it by up to 19.66%,which leads to the decline in oblique shock wave strength.The oblique shock waves in front of the ramp move upstream by the action of the Lorentz body force.The discharge characteristics are analyzed and the MHD interaction time and consumed energy are determined with the help of the pulsed DC discharge images.The interaction parameter corresponding to the boundary layer velocity can reach 1.3 from the momentum conservation equation.The velocity of the plasma column in the magnetic field is much faster than that in the absence of magnetic field force.The plasma can strike the neutral gas molecules to transfer momentum and accelerate the flow around the ramp.展开更多
This paper presents a preliminary experimental investigation on magnetohydrodynamic （MHD） power generation using seeded supersonic argon flow as working fluid. Helium and argon are used as driver and driven gas resp...This paper presents a preliminary experimental investigation on magnetohydrodynamic （MHD） power generation using seeded supersonic argon flow as working fluid. Helium and argon are used as driver and driven gas respectively in a shock tunnel. Equilibrium contact surface operating mode is used to obtain high temperature gas, and the conductivity is obtained by adding seed K2CO3 powder into the driven section. Under the conditions of nozzle inlet total pressure being 0.32 MPa, total temperature 6 504 K, magnetic field density about 0.5 T and nozzle outlet velocity 1 959 m/s, induction voltage and short-circuit current of the segmentation MHD power generation channel are measured, and the experimental results agree with theoretical calculations; the average conductivity is about 20 S/m calculated from characteristics of voltage and current. When load factor is 0.5, the maximum power density of the MHD power generation channel reaches 4.797 1 MW/m3, and the maximum enthalpy extraction rate is 0.34%. Finally, the principle and method of indirect testing for gas state parameters are derived and analyzed.展开更多
Weak feature extraction is of great importance for condition monitoring and intelligent diagnosis of aeroengine.Aimed at achieving intelligent diagnosis of aero-engine main shaft bearing,an enhanced sparsity-assisted ...Weak feature extraction is of great importance for condition monitoring and intelligent diagnosis of aeroengine.Aimed at achieving intelligent diagnosis of aero-engine main shaft bearing,an enhanced sparsity-assisted intelligent condition monitoring method is proposed in this paper.Through analyzing the weakness of convex sparse model,i.e.the tradeoff between noise reduction and feature reconstruction,this paper proposes an enhanced-sparsity nonconvex regularized convex model based on Moreau envelope to achieve weak feature extraction.Accordingly,a sparsity-assisted deep convolutional variational autoencoders network is proposed,which achieves the intelligent identification of fault state through training denoised normal data.Finally,the effectiveness of the proposed method is verified through aero-engine bearing run-to-failure experiment.The comparison results show that the proposed method is good at abnormal pattern recognition,showing a good potential for weak fault intelligent diagnosis of aero-engine main shaft bearings.展开更多
OBJECTIVE:To investigate the potential mechanism of the vascular remodeling effect and provide additional information about anti-hypertension activity of Fufang Qima capsule(复方芪麻胶囊,QM).METHODS:Spontaneous hypert...OBJECTIVE:To investigate the potential mechanism of the vascular remodeling effect and provide additional information about anti-hypertension activity of Fufang Qima capsule(复方芪麻胶囊,QM).METHODS:Spontaneous hypertensive rats(SHRs)were used to study the underlying mechanism of the anti-hypertension activity of QM.In this study,SHRs were randomly divided into 5 groups:model group,Telmisartan group(7.2 mg/kg,p.o.),and three QM groups(0.9298,1.8596,and 3.7192 g/kg,p.o.).Wistar Kyoto rats(WKY)were used as normal control group.Blood pressure(BP),aorta,perivascular adipose tissue(PVAT)histology were investigated to evaluate the effect of QM.Nitric oxide(NO)and endothelial nitric oxide synthase(eNOS)phosphorylation were measured.Adiponectin(APN)secretion,as well as APN signal pathway proteins including APN,adiponectin receptors(R1 and R2)and adenosine 5’-monophosphate-activated protein kinase(AMPK)were all analyzed.RESULTS:QM significantly reduced BP and ameliorated the vascular pathological change,i.e.intima media thicken and collagen fiber hyperplasia.Meanwhile,QM increased concentration of NO and the phosphorylation of eNOS in the aorta.The anti-hypertensive and endothelia-protective effect of QM could be attributed to activating APN/AMPK pathway by up-regulating the expression of APN in PVAT and APN Receptor 2,AMPKαand phosphorylated AMPKαin the aorta.CONCLUSION:The QM alleviation effect mechanism for primary hypertension was via modulating the APN/AMPK signal pathway.展开更多
The widely expected phase two project of Beijing Star River will open its phase two model units to the public on Oct. 19, and by then Beijing Star River, which has long been regarded as the paradigm of good residence,...The widely expected phase two project of Beijing Star River will open its phase two model units to the public on Oct. 19, and by then Beijing Star River, which has long been regarded as the paradigm of good residence, will unveil its long-awaited phase two offering. The reporter took the lead to pay a visit to the phase two model units recently. The fully innovated phase two products are still ready-made residence, and the quality is even higher.展开更多
The central bank of China has raised her deposit rate for 6 times,and deposit reserve rate for 16 times,since last year up to now,which resulted to a great suffer to those small and medium sized enterprises in finance...The central bank of China has raised her deposit rate for 6 times,and deposit reserve rate for 16 times,since last year up to now,which resulted to a great suffer to those small and medium sized enterprises in finance collection.30 percent of China s small and medium sized enterprises have to be closed down, and 60 percent of them are because of finance problem.How to gather the fund is the biggest obstacle for China's enterprises to grow.展开更多
基金National Natural Science Foundation of China(50776100)
文摘This article is devoted to experimental study on the control of the oblique shock wave around the ramp in a low-temperature supersonic flow by means of the magnetohydrodynamic(MHD)flow control technique.The purpose of the experiments is to take advantage of MHD interaction to weaken the oblique shock wave strength by changing the boundary flow characteristics around the ramp.Plasma columns are generated by pulsed direct current(DC)discharge,the magnetic fields are generated by Nd-Fe-B rare-earth permanent magnets and the oblique shock waves in supersonic flow are generated by the ramp.The Lorentz body force effect of MHD interaction on the plasma-induced airflow velocity is verified through particle image velocimetry(PIV)measurements.The experimental results from the supersonic wind tunnel indicate that the MHD flow control can drastically change the flow characteristics of the airflow around the ramp and decrease the ratio of the Pitot pressure after shock wave to that before it by up to 19.66%,which leads to the decline in oblique shock wave strength.The oblique shock waves in front of the ramp move upstream by the action of the Lorentz body force.The discharge characteristics are analyzed and the MHD interaction time and consumed energy are determined with the help of the pulsed DC discharge images.The interaction parameter corresponding to the boundary layer velocity can reach 1.3 from the momentum conservation equation.The velocity of the plasma column in the magnetic field is much faster than that in the absence of magnetic field force.The plasma can strike the neutral gas molecules to transfer momentum and accelerate the flow around the ramp.
基金National Natural Science Foundation of China （10972236） The Scientific and Technical Innovation for Postgraduates of Air Force Engineering University （DX2010102）
文摘This paper presents a preliminary experimental investigation on magnetohydrodynamic （MHD） power generation using seeded supersonic argon flow as working fluid. Helium and argon are used as driver and driven gas respectively in a shock tunnel. Equilibrium contact surface operating mode is used to obtain high temperature gas, and the conductivity is obtained by adding seed K2CO3 powder into the driven section. Under the conditions of nozzle inlet total pressure being 0.32 MPa, total temperature 6 504 K, magnetic field density about 0.5 T and nozzle outlet velocity 1 959 m/s, induction voltage and short-circuit current of the segmentation MHD power generation channel are measured, and the experimental results agree with theoretical calculations; the average conductivity is about 20 S/m calculated from characteristics of voltage and current. When load factor is 0.5, the maximum power density of the MHD power generation channel reaches 4.797 1 MW/m3, and the maximum enthalpy extraction rate is 0.34%. Finally, the principle and method of indirect testing for gas state parameters are derived and analyzed.
基金the National Natural Science Foundations of China(Nos.91860125,51705398)the National Key Basic Research Program of China(No.2015CB057400)the Shaanxi Province 2020 Natural Science Basic Research Plan(No.2020JQ-042).
文摘Weak feature extraction is of great importance for condition monitoring and intelligent diagnosis of aeroengine.Aimed at achieving intelligent diagnosis of aero-engine main shaft bearing,an enhanced sparsity-assisted intelligent condition monitoring method is proposed in this paper.Through analyzing the weakness of convex sparse model,i.e.the tradeoff between noise reduction and feature reconstruction,this paper proposes an enhanced-sparsity nonconvex regularized convex model based on Moreau envelope to achieve weak feature extraction.Accordingly,a sparsity-assisted deep convolutional variational autoencoders network is proposed,which achieves the intelligent identification of fault state through training denoised normal data.Finally,the effectiveness of the proposed method is verified through aero-engine bearing run-to-failure experiment.The comparison results show that the proposed method is good at abnormal pattern recognition,showing a good potential for weak fault intelligent diagnosis of aero-engine main shaft bearings.
基金Supported by the Project From the Department of Guangdong Science and Technology(Establishment and Promotion of TCM Prevention and Treatment Network of Hypertension,No.2017A020213010)Guangdong TCM Science and Technology Innovation Platform Project(Research on Prevention and Treatment of Cardio-cerebrovascular Diseases with TCM,No.Guangdong Traditional Chinese Medicine Letter[2018]No.6)China Administration of Traditional Chinese Medicine the Old Famous Experts Inheritance Studio Construction project(China TCM File[2016]No.42)。
文摘OBJECTIVE:To investigate the potential mechanism of the vascular remodeling effect and provide additional information about anti-hypertension activity of Fufang Qima capsule(复方芪麻胶囊,QM).METHODS:Spontaneous hypertensive rats(SHRs)were used to study the underlying mechanism of the anti-hypertension activity of QM.In this study,SHRs were randomly divided into 5 groups:model group,Telmisartan group(7.2 mg/kg,p.o.),and three QM groups(0.9298,1.8596,and 3.7192 g/kg,p.o.).Wistar Kyoto rats(WKY)were used as normal control group.Blood pressure(BP),aorta,perivascular adipose tissue(PVAT)histology were investigated to evaluate the effect of QM.Nitric oxide(NO)and endothelial nitric oxide synthase(eNOS)phosphorylation were measured.Adiponectin(APN)secretion,as well as APN signal pathway proteins including APN,adiponectin receptors(R1 and R2)and adenosine 5’-monophosphate-activated protein kinase(AMPK)were all analyzed.RESULTS:QM significantly reduced BP and ameliorated the vascular pathological change,i.e.intima media thicken and collagen fiber hyperplasia.Meanwhile,QM increased concentration of NO and the phosphorylation of eNOS in the aorta.The anti-hypertensive and endothelia-protective effect of QM could be attributed to activating APN/AMPK pathway by up-regulating the expression of APN in PVAT and APN Receptor 2,AMPKαand phosphorylated AMPKαin the aorta.CONCLUSION:The QM alleviation effect mechanism for primary hypertension was via modulating the APN/AMPK signal pathway.
文摘The widely expected phase two project of Beijing Star River will open its phase two model units to the public on Oct. 19, and by then Beijing Star River, which has long been regarded as the paradigm of good residence, will unveil its long-awaited phase two offering. The reporter took the lead to pay a visit to the phase two model units recently. The fully innovated phase two products are still ready-made residence, and the quality is even higher.
文摘The central bank of China has raised her deposit rate for 6 times,and deposit reserve rate for 16 times,since last year up to now,which resulted to a great suffer to those small and medium sized enterprises in finance collection.30 percent of China s small and medium sized enterprises have to be closed down, and 60 percent of them are because of finance problem.How to gather the fund is the biggest obstacle for China's enterprises to grow.
