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Rethinking the solar flare paradigm

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Plasma Science and Technology 2018年第7期20卷 15-21页

作者： d b melrose SIfA School of PhysicsThe University of SydneyNSW 2006Australi

It is widely accepted that solar flares involve release of magnetic energy stored in the solar corona above an active region, but existing models do not include the explicitly time-dependent electrodynamics needed to describe such energy release. A flare paradigm is discussed that includes the electromotive force （EMF） as the driver of the flare, and the flare-associated current that links different regions where magnetic reconnection, electron acceleration, the acceleration of mass motions and current closure occur. The EMF becomes localized across regions where energy conversion occurs, and is involved in energy propagation between these regions.

关键词： solar flares electrodynamics time-dependence

Oil spill model development and application for emergency response system

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Journal of Environmental Sciences 2001年第2期13卷 252-256页

作者： b Qiao Environmental Science Center Peking University Beijing 100871 China.

The paper introduces systematically the developing principle of CWCM 1.0 oil spill model based on Lagrange system and oil spill fate processes in environment, reviews two oil spill incidents of "East Ambassador" in Jiaozhou bay and "Min Fuel 2" in the mouth of Pearl River, and designs the predictable system simulating oil spill applied in contingency plans. It is indicated that CWCM 1.0 has met preliminarily the demands for functions of precision simulating and predicting oil spill, and can plan an important role to support oil spill response.

关键词： Oil spill model development and application for emergency response system

The p38-MAPK Pathway Is Involved in Neuroprotection of Artemisinin against H2O2-induced Apoptosis in PC12 Cells

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Journal of Pharmacy and Pharmacology 2017年第7期5卷 416-423页

作者： Liu Linlin Zhiwen Zeng uma Gaur Fengxia Yan Wenhua Zheng Faculty of Health Sciences University of Macao Macao 999078 China

Oxidative stress, owing to the excessive production of ROS （reactive oxygen species）, is one of the leading causes for the progression of AD （Alzheimer＇s disease）. Increasing evidences suggested that oxidative stress insult impaired the physiological functioning of neuronal cells by inducing cell apoptosis. The search for drug candidates that can effectively protect neurons from oxidative stress insult might hold therapeutic potential for AD. In the present study, we tested the neuroprotective effects and the related action mechanisms of artemisinin, a FDA-approved anti-malarial drug, against H2O2 induced oxidative damage in PC12 cells. It was found that artemisinin reduced cell viability loss caused by hydrogen peroxide （H2O2） in PC12 cells. In addition, data from Flow cytometry displayed that artemisinin significantly decreased the apoptosis of PC 12 cells induced by H2O2. Furthermore Western blot analysis displayed that artemisinin stimulated the p38MAPK signaling, while treatment of PC 12 cells with specific p38MAPK pathway inhibitor Sb203580 blocked the neuroprotective effect of artemisinin. These results together indicated that artemisinin is a potential protectant, and it protects PC12 cells against H2O2 injury through activation of the p38MAPK pathway.

关键词： Artemisinin oxidative stress AD PC12 cells p38MAPK.

Analysis of non-symmetrical flapping airfoils

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Acta Mechanica Sinica 2009年第4期25卷 433-450页

作者： W.b.Tay K.b.Lim Department of Mechanical Engineering National University of Singapore

Simulations have been done to assess the lift, thrust and propulsive efficiency of different types of non-symmetrical airfoils under different flapping configurations. The variables involved are reduced frequency, Strouhal number, pitch amplitude and phase angle. In order to analyze the variables more efficiently, the design of experiments using the response surface methodology is applied. Results show that both the variables and shape of the airfoil have a profound effect on the lift, thrust, and efficiency. by using non- symmetrical airfoils, average lift coefficient as high as 2.23 can be obtained. The average thrust coefficient and efficiency also reach high values of 2.53 and 0.61, respectively. The lift production is highly dependent on the airfoil＇s shape while thrust production is influenced more heavily by the variables. Efficiency falls somewhere in between. Two-factor interac- tions are found to exist among the variables. This shows that it is not sufficient to analyze each variable individually. Vorticity diagrams are analyzed to explain the results obtained. Overall, the S1020 airfoil is able to provide relatively good efficiency and at the same time generate high thrust and lift force. These results aid in the design of a better ornithopter＇s wing.

关键词： Flapping Non-symmetrical Design ofexperiments Ornithopter Airfoil

Microstructure and Mechanical Properties of Mg–7.4% Al Alloy Matrix Composites Reinforced by Nanocrystalline Al–Ca Intermetallic Particles

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Acta Metallurgica Sinica(English Letters) 2015年第4期28卷 444-448页

作者： A.K.Chaubey b.b.Jha b.K.Mishra Institute of Minerals and Materials Technology (IMMT)

Mg-7.6% Al （in mass fraction） alloy matrix composites reinforced with different volume fractions of nano- crystalline Al3Cas particles were synthesized by powder metallurgy, and the effect of the volume fraction of reinforcement on the mechanical properties was studied. Room temperature compression test reveals considerable improvement on mechanical properties as compared to unreinforced matrix. The compressive strength increases from 683 MPa for unre- inforced alloy matrix to about 767 and 823 MPa for the samples having 20 and 40 vol% of reinforcement, respectively, while retaining appreciable plastic deformation ranging between 12 and 24%. The specific strength of the composites increased significantly, demonstrating the effectiveness of the low-density AlaCas reinforcement.

关键词： Intermetallics Consolidation Dispersion strengthening Powder metallurgy Mechanicalproperty Electron microscopy

Synthesis, Characterization and Crystal Structure of bis[1 -meth oxy-2,2,2-tris-（pyrazol-1 -yl-KN2）ethane]-coppe r（Ⅱ） bis-perchlorate

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Journal of Chemistry and Chemical Engineering 2016年第5期10卷 207-211页

作者： Ganna Lyubartseva Sean Parkin Shamiso Ngongoni uma Prasad Mallik Department of biochemistry and Chemistry Southern Arkansas University Magnolia AR 71753 USA Department of Chemistry University of Kentucky Lexington KY40506 USA Department of Engineering and Physics Southern Arkansas University Magnolia AR 71753 USA

bis[1-methoxy-2,2,2-tris-（pyrazol-l-yl-KN2）ethane]-copper（Ⅱ） bis-perchlorate （2） was synthesized by reacting of pyrazole based tripodal scorpionate ligand 1-methoxy-2,2,2-tris（pyrazol-1-yl）ethane （1） with copper（Ⅱ） perchlorate hexahydrate in methanol, acetonitrile and water mixture as solvent. Slow evaporation of the filtered reaction mixture in air produced blue color block crystals suitable for single crystal X-ray diffraction study of the title complex. Compound 2 crystallizes in the monoclinic space group P21/n with unit cell parameters, α = 8.1269（1） ,A, b = 21.8348（2）A, c = 9.1522（1） A, a = γ= 90° , β = 99.7611 （4）°. The structure of the compound was characterized by IR Spectroscopy, elemental analysis and single crystal X-ray diffraction analysis.

关键词： Pyrazole tripodal ligand scorpionate ligand single crystal X-ray diffraction.

Numerical analysis of the s1020 airfoils in tandem under different flapping configurations

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Acta Mechanica Sinica 2010年第2期26卷 191-207页

作者： K.b.Lim W.b.Tay Department of Mechanical Engineering National University of Singapore21 Lower Kent Ridge RoadSingapore 119077Singapore

The objective of this project is to improve the performance of the efficiency, thrust and lift of flapping wings in tandem arrangement. This research investigates the effect of the arrangement of the airfoils in tandem on the performance of the airfoils by varying the phase difference and distance between the airfoils. Three flapping configurations from an earlier phase of a research which gives high efficiency, thrust and lift are used in the tandem simulation. It is found all the different flapping configurations show improvement in the efficiency, thrust or lift when the distance between the two airfoils and the phase angle between the heaving positions of the two airfoils are optimal. The average thrust coefficient of the tandem arrangement managed to attain more than twice that of the single one （4.84 vs. 2.05）. On the other hand, the average lift coefficient of the tandem arrangement also increased to 4.59, as compared to the original single airfoil value of 3.04. All these results obtained will aid in the design of a better ornithopter with tandem wing arrangement.

关键词： Tandem Flapping· Airfoils Ornithopter·Immersed boundary

Generating a New Higher-Dimensional Coupled Integrable Dispersionless System:Algebraic Structures,bcklund Transformation and Hidden Structural Symmetries

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Communications in Theoretical Physics 2013年第8期60卷 145-149页

作者： Souleymanou Abbagari Thomas b.bouetou Timoleon C.Kofane National Advanced School of Engineering University of Yaounde IP.O.Box 8390Cameroon Department of Physics Faculty of ScienceUniversity of Yaounde IP.O.Box 812Cameroon The Max Planck Institute for the Physics of Complex Systems Nthnitzer Strasse 3801187 DresdenGermany

The prolongation structure methodologies of Wahlquist-Estabrook [H.D. Wahlquist and F.b. Estabrook, J. Math. Phys. 16 （1975） 1] for nonlinear differential equations are applied to a more general set of coupled integrable dispersionless system. based on the obtained prolongation structure, a Lie-Algebra valued connection of a closed ideal of exterior differential forms related to the above system is constructed. A Lie-Algebra representation of some hidden structural symmetries of the previous system, its biicklund transformation using the Riccati form of the linear eigenvalue problem and their general corresponding Lax-representation are derived. In the wake of the previous results, we extend the above prolongation scheme to higher-dimensional systems from which a new （2 ＋ 1）-dimensional coupled integrable dispersionless system is unveiled along with its inverse scattering formulation, which applications are straightforward in nonlinear optics where additional propagating dimension deserves some attention.

关键词： coupled integrable dispersionless system algebraic structures b^cklund transformation Hiddenstructural symmetries

Dedicated to Professor Dr.-Ing. ***.h.c. Jurgen Zierep for his 80^(th) birthday Pattern Formation in Rotating Fluids

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Journal of Thermal Science 2009年第2期18卷 109-118页

作者： Karl bühler Department of Mechanical and Process Engineering University of Applied Sciences

Flows in nature and technology are often associated with specific structures and pattern. This paper deals with thedevelopment and behaviour of such flow pattern. Flow structures are important for the mass, momentum and energytransport. The behaviour of different flow pattern is used by engineers to obtain an efficient mass and energyconsumption. Mechanical power is transmitted via the momentum of rotating machine parts. Therefore thephysical and mathematical knowledge of these basic concepts is important. Theoretical and experimental investigationsof principle experiments are described in the following. We start with the classical problem of the flowbetween two concentric cylinders where the inner cylinder rotates. Periodic instabilities occur which are calledTaylor vortices. The analogy between the cylindrical gap flow, the heat transfer in a horizontal fluid layer exposedto the gravity field and the boundary layer flow along concave boundaries concerning their stability behaviour isaddressed. The vortex breakdown phenomenon in a cylinder with rotating cover is also described. A generalizationto spherical sectors leads then to investigations with different boundary conditions. The spherical gap flowexhibits interesting phenomena concerning the nonlinear character of the Navier-Stokes equations. Multiple solutionsin the nonlinear regime give rise to different routes during the laminar-turbulent transition. The interactionof two rotating spheres results in flow structures with separation and stagnation lines. Experimental results areconfirmed by numerical simulations.

关键词： Rotating Fluids Stability behaviour bifurcation Vortices Laminar-turbulent Transition