动脉粥样硬化是心血管疾病重要的病理生理基础,延缓和防治动脉粥样硬化对于减少和降低心血管疾病的发病率及病死率具有重要意义。高密度脂蛋白(high density lipoprotein,HDL)通过参与介导胆固醇逆向转运(reverse cholesterol transport...动脉粥样硬化是心血管疾病重要的病理生理基础,延缓和防治动脉粥样硬化对于减少和降低心血管疾病的发病率及病死率具有重要意义。高密度脂蛋白(high density lipoprotein,HDL)通过参与介导胆固醇逆向转运(reverse cholesterol transport,RCT)在抗动脉粥样硬化的形成和进展中发挥了重要作用。Preβ-1高密度脂蛋白(prebeta-1 high density lipoprotein,Preβ-1HDL)作为HDL的一种亚类,是外周细胞移出胆固醇的最初接受体,直接参与了RCT的起始步骤,并在随后的胆固醇酯化及转运中起着重要作用。本文就Preβ-1HDL的结构、代谢及其与心血管疾病的关系作一简要综述。展开更多
An oblique detonation wave for a Mach 7 inlet flow over a long enough wedge of 30 turning angle is simulated numerically using Euler equation and one-step rection model.The fifth-order WENO scheme is adopted to captur...An oblique detonation wave for a Mach 7 inlet flow over a long enough wedge of 30 turning angle is simulated numerically using Euler equation and one-step rection model.The fifth-order WENO scheme is adopted to capture the shock wave.The numerical results show that with the compression of the wedge wall the detonation wave front structure is divided into three sections：the ZND model-like strcuture,single-sided triple point structure and dual-headed triple point strucuture.The first structure is the smooth straight,and the second has the characteristic of the triple points propagating dowanstream only with the same velocity,while the dual-headed triple point structure is very complicated.The detonation waves facing upstream and downstream propagate with different velocities,in which the periodic collisions of the triple points cause the oscillation of the detonation wave front.This oscillation process has temporal and spatial periodicity.In addition,the triple point trace are recorded to obtain different cell structures in three sections.展开更多
Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate ...Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.展开更多
In this paper, detonation parameters of fuel cloud, such as propylene oxide （PO）, isopropyl nitrate （IPN）, hex- ane, 90# oil and decane were measured in a self-designed and constructed vertical shock tube. Results...In this paper, detonation parameters of fuel cloud, such as propylene oxide （PO）, isopropyl nitrate （IPN）, hex- ane, 90# oil and decane were measured in a self-designed and constructed vertical shock tube. Results show that the deto- nation pressure and velocity of PO increase to a peak value and then decrease smoothly with increasing equivalence ra- tio. Several nitrate sensitizers were added into PO to make fuel mixtures, and test results indicated that the additives can efficiently enhance detonation velocity and pressure of fuel cloud and one type of additive n-propyl nitrate （NPN） played the best in the improvement. The critical initiation energy that directly initiated detonation of all the test liquid fuel clouds showed a U-shape curve relationship with equiva- lence ratios. The optimum concentration lies on the rich-fuel side （;b 〉 1）. The critical initiation energy is closely related to molecular structure and volatility of fuels. IPN and PO have similar critical values while that of alkanes are larger. Detonation cell sizes of PO were respectively investigated at 25;C, 35;C and 50;C with smoked foil technique. The cell width shows a U-shape curve relationship with equivalence ratios at all temperatures. The minimal cell width also lies on the rich-fuel side （;b 〉 1）. The cell width of PO vapor is slightly larger than that of PO cloud. Therefore, the deto- nation reaction of PO at normal temperature is controlled by gas phase reaction.展开更多
鉴于爆震燃烧具有自增压、传播速度快等优点,提出了将燃气轮机中等压燃烧替换为爆震燃烧的理念,并建立了基于爆震燃烧的燃气轮机理想热力循环模型,对比研究了DCGT(detonation cycle of gas turbine)、Brayton和Humphrey 3种循环燃气轮...鉴于爆震燃烧具有自增压、传播速度快等优点,提出了将燃气轮机中等压燃烧替换为爆震燃烧的理念,并建立了基于爆震燃烧的燃气轮机理想热力循环模型,对比研究了DCGT(detonation cycle of gas turbine)、Brayton和Humphrey 3种循环燃气轮机的综合性能。在压气机压比、吸热量和透平背压相同的条件下,数据分析结果表明DCGT循环燃气轮机较其他2种循环更具优势,在压比为16时其循环热效率较Brayton循环提高15.4%,燃料消耗率降低13.5%;DCGT循环燃气轮机在压比为6.6时的总体性能与压比为16时的Brayton循环相当。展开更多
文摘动脉粥样硬化是心血管疾病重要的病理生理基础,延缓和防治动脉粥样硬化对于减少和降低心血管疾病的发病率及病死率具有重要意义。高密度脂蛋白(high density lipoprotein,HDL)通过参与介导胆固醇逆向转运(reverse cholesterol transport,RCT)在抗动脉粥样硬化的形成和进展中发挥了重要作用。Preβ-1高密度脂蛋白(prebeta-1 high density lipoprotein,Preβ-1HDL)作为HDL的一种亚类,是外周细胞移出胆固醇的最初接受体,直接参与了RCT的起始步骤,并在随后的胆固醇酯化及转运中起着重要作用。本文就Preβ-1HDL的结构、代谢及其与心血管疾病的关系作一简要综述。
基金supported by the National Natural Science Foundation of China (10872096)the Open Fund of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology (KFJJ09-13)
文摘An oblique detonation wave for a Mach 7 inlet flow over a long enough wedge of 30 turning angle is simulated numerically using Euler equation and one-step rection model.The fifth-order WENO scheme is adopted to capture the shock wave.The numerical results show that with the compression of the wedge wall the detonation wave front structure is divided into three sections：the ZND model-like strcuture,single-sided triple point structure and dual-headed triple point strucuture.The first structure is the smooth straight,and the second has the characteristic of the triple points propagating dowanstream only with the same velocity,while the dual-headed triple point structure is very complicated.The detonation waves facing upstream and downstream propagate with different velocities,in which the periodic collisions of the triple points cause the oscillation of the detonation wave front.This oscillation process has temporal and spatial periodicity.In addition,the triple point trace are recorded to obtain different cell structures in three sections.
基金supported by the National Natural Science Foundation of China (10872096)the Open Fund of State Key Laboratory of Explosion Science and Technology, Beijing University of Science and Technology (KFJJ09-13)
文摘Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.
文摘In this paper, detonation parameters of fuel cloud, such as propylene oxide （PO）, isopropyl nitrate （IPN）, hex- ane, 90# oil and decane were measured in a self-designed and constructed vertical shock tube. Results show that the deto- nation pressure and velocity of PO increase to a peak value and then decrease smoothly with increasing equivalence ra- tio. Several nitrate sensitizers were added into PO to make fuel mixtures, and test results indicated that the additives can efficiently enhance detonation velocity and pressure of fuel cloud and one type of additive n-propyl nitrate （NPN） played the best in the improvement. The critical initiation energy that directly initiated detonation of all the test liquid fuel clouds showed a U-shape curve relationship with equiva- lence ratios. The optimum concentration lies on the rich-fuel side （;b 〉 1）. The critical initiation energy is closely related to molecular structure and volatility of fuels. IPN and PO have similar critical values while that of alkanes are larger. Detonation cell sizes of PO were respectively investigated at 25;C, 35;C and 50;C with smoked foil technique. The cell width shows a U-shape curve relationship with equivalence ratios at all temperatures. The minimal cell width also lies on the rich-fuel side （;b 〉 1）. The cell width of PO vapor is slightly larger than that of PO cloud. Therefore, the deto- nation reaction of PO at normal temperature is controlled by gas phase reaction.
文摘鉴于爆震燃烧具有自增压、传播速度快等优点,提出了将燃气轮机中等压燃烧替换为爆震燃烧的理念,并建立了基于爆震燃烧的燃气轮机理想热力循环模型,对比研究了DCGT(detonation cycle of gas turbine)、Brayton和Humphrey 3种循环燃气轮机的综合性能。在压气机压比、吸热量和透平背压相同的条件下,数据分析结果表明DCGT循环燃气轮机较其他2种循环更具优势,在压比为16时其循环热效率较Brayton循环提高15.4%,燃料消耗率降低13.5%;DCGT循环燃气轮机在压比为6.6时的总体性能与压比为16时的Brayton循环相当。
