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Effect of hydration on the elasticity of mantle minerals and its geophysical implications

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Science China Earth Sciences 2016年第5期59卷 873-888页

作者： mao Zhu LI XinYang Laboratory of Seismology and Physics of Earth's Interior School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China National Geophysics Observatory at Mengcheng Mengcheng 233500 China

Recent studies have shown that major nominally anhydrous minerals in the Earth's mantle, such as olivine, pyroxene and garnet, can incorporate considerable amounts of water as structurally bound hydroxyl. Even a small amount of water is present in mantle minerals, it can strongly affect a number of physical properties, including density, sound velocity, melting temperature, and electrical conductivities. The presence of water can also influence the dynamic behavior, lead to lateral velocity heterogeneities, and affect the material circulation of the Earth's deep interior. In particular, seismic studies have reported the existence of low-velocity zones in various locations of the Earth's upper mantle and transition zone, which has been expected to be associated with the presence of water in the region. In the past two decades, the effect of water on the elasticity and sound velocities of minerals at relevant pressure-temperature(P-T) conditions of the Earth's mantle attracted extensive interests. Combining the high P-T experimental and theoretical mineralogical results with seismic observations provides crucial constraints on the distribution of water in the Earth's mantle. In this study, we summarize recent experimental and theoretical mineral physics results on how water affects the elasticity and sound velocity of nominally anhydrous minerals in the Earth's mantle, which aims to provide new insights into the effect of hydration on the density and velocity profile of the Earth's mantle, which are of particular importance in understanding of water distribution in the region.

关键词： Water Elasticity Sound velocity Upper mantle Transition zone Olivine polymorphs

The effects of corrugation and wing planform on the aerodynamic force production of sweeping model insect wings

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Acta Mechanica Sinica 2005年第6期21卷 531-541页

作者： Guoyu Luo mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Institute of Fluid Mechanics Beihang University Beijing 100083 China

The effects of corrugation and wing planform （shape and aspect ratio） on the aerodynamic force production of model insect wings in sweeping （rotating after an initial start） motion at Reynolds number 200 and 3500 at angle of attack 40℃ are investigated, using the method of computational fluid dynamics. A representative wing corrugation is considered. Wing-shape and aspect ratio （AR） of ten representative insect wings are considered; they are the wings of fruit fly, cranefly, dronefly, hoverfly, ladybird, bumblebee, honeybee, lacewing （forewing）, hawkmoth and dragon- fly （forewing）, respectively （AR of these wings varies greatly, from 2.84 to 5.45）. The following facts are shown. （1） The corrugated and flat-plate wings produce approximately the same aerodynamic forces. This is because for a sweeping wing at large angle of attack, the length scale of the corrugation is much smaller than the size of the separated flow region or the size of the leading edge vortex （LEV）. （2） The variation in wing shape can have considerable effects on the aerodynamic force; but it has only minor effects on the force coefficients when the velocity at r2 （the radius of the second ：moment of wing area） is used as the reference velocity; i.e. the force coefficients are almost unaffected by the variation in wing shape. （3） The effects of AR are remarkably small： whenAR increases from 2.8 to 5.5, the force coefficients vary only slightly; flowfield results show that when AR is relatively large, the part of the LEV on the outer part of the wings sheds during the sweeping motion. As AR is increased, on one hand, the force coefficients will be increased due to the reduction of 3-dimensional flow effects; on the other hand, they will be decreased due to the shedding of part of the LEV; these two effects approximately cancel each other, resulting in only minor change of the force coefficients.

关键词： insect flight - Sweeping wing Unsteady aerodynamics Wing corrugation Planform

Parameter-dependent vibration-attenuation controller design for electro-hydraulic actuated linear structural systems

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Earthquake Engineering and Engineering Vibration 2012年第1期11卷 73-82页

作者： Weng Falu mao Weijie State Key Lab of Industrial Control Technology Institute of Cyber-Systems and Control Zhejiang University Hangzhou 310027 China School of Mechanical and Electrical Engineering Jiangxi University of Science and Technology Ganzhou 341000 China

The problem of robust active vibration control for a class of electro-hydraulic actuated structural systems with time-delay in the control input channel and parameter uncertainties appearing in all the mass, damping and stiffness matrices is investigated in this paper. First, by introducing a linear varying parameter, the nonlinear system is described as a linear parameter varying （LPV） model. Second, based on this LPV model, an LMI-based condition for the system to be asymptotically stabilized is deduced. By solving these LMIs, a parameter-dependent controller is established for the closed- loop system to be stable with a prescribed level of disturbance attenuation. The condition is also extended to the uncertain case. Finally, some numerical simulations demonstrate the satisfying performance of the proposed controller.

关键词： structural system electro-hydraulic servo system robust stabilization vibration attenuation parameter-dependent controller

Dynamic flight stability of a model dronefly in vertical flight

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Acta Mechanica Sinica 2014年第6期30卷 828-838页

作者： Chong Shen mao Sun Institute of Fluid Mechanics Beijing University of Aeronautics & Astronautics

The dynamic flight stability of a model dronefly in hovering and upward flight is *** method of computational fluid dynamics is used to compute the stability derivatives and the techniques of eigenvalue and eigenvector used to solve the equations of *** major finding is as *** flight of the model dronefly is unstable because of the existence of an unstable longitudinal and an unstable lateral natural mode of *** flight of the insect is also unstable,and the instability increases as the upward flight speed *** force generated by the upward flight velocity coupled with the disturbance in pitching angular velocity is responsible for the enhancement of the instability.

关键词： Insect vertical flight Flight stability Natural modes of motion

Aerodynamic Effects of Corrugation in Flapping Insect Wings in Forward Flight

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Journal of Bionic Engineering 2011年第2期8卷 140-150页

作者： Xueguang Meng mao Sun Ministry-of-Education Key Laboratory of Fluid Mechanics Beijing University of Aeronautics & Astronautics Beijing 100083 P. R. China

We have examined the aerodynamic effects of corrugation in model wings that closely mimic the wing movements of a forward flight bumblebee using the method of computational fluid dynamics. Various corrugated wing models were tested （care was taken to ensure that the corrugation introduced zero camber）. Advance ratio ranging from 0 to 0.57 was considered. The results shown that at all flight speeds considered, the time courses of aerodynamic force of the corrugated wing are very close to those of the flat-plate wing. The cornlgation decreases aerodynamic force slightly. The changes in the mean location of center of pressure in the spanwise and chordwise directions resulting from the corrugation are no more than 3% of the wing chord length. The possible reason for the small aerodynamic effects of wing corrugation is that the wing operates at a large angle of attack and the flow is separated： the large angle of incidence dominates the corrugation in determining the flow around the wing, and for separated flow, the flow is much less sensitive to wing shape variation.

关键词： insect flapping forward flight wing corrugation aerodynamics

Characterization of Leaf-Inspired Microfluidic Chips for Pumpless Fluid Transport

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Journal of Bionic Engineering 2014年第1期11卷 109-114页

作者： Jiankang He mao mao Dichen Li Yaxiong Liu Zhongmin Jin State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi 'an 710049 P. R. China

Microfluidic networks are extensively used in miniaturized lab-on-a-chip systems. However, most of the existing micro- channels are simply designed and the corresponding microfluidic systems commonly require external pumps to achieve effec- tive fluid transport. Here we employed microfabrication techniques to replicate naturally-optimized leaf venations into synthetic hydrogels for the fabrication of pumpless microfluidic chips. The unique properties of leaf-inspired microfluidic network in convectively transporting fluid were characterized at different inclination angles. Flow velocity inside these microfluidic net- works was quantitatively measured with Particle Image Velocimetry （PIV）. Mass diffusion from biomimetic microfluidic network to surrounding bulk hydrogels was investigated. The results demonstrate that the leaf-inspired microfluidic network can not only effectively transport fluid without the use of external pumps, but also facilitate rapid mass diffusion within bulk hy- drogel chips. These leaf-inspired microfluidic networks could be potentially used to engineer complex pumpless or- gan-on-a-chip systems.

关键词： leaf-inspired microfluidic network pumpless lab-on-a-chip system biomimetics

Computational chemical engineering–Towards thorough understanding and precise application

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Chinese Journal of Chemical Engineering 2016年第8期24卷 945-951页

作者： Zaisha mao Chao Yang Key Laboratory of Green Process and Engineering Institute of Process Engineering Chinese Academy of Sciences

The paradigms of chemical engineering discipline are discussed. The first paradigm of Unit Operations and the second paradigm of Transport Phenomena are well recognized among the chemical engineers all over the world, and what the next paradigm is remains still an open question. Several proposals such as Chemical product engineering, Sustainable chemical engineering and Multi-scale methodology are considered as candidates for next paradigm. Might Computational Chemical Engineering be the next one, which is advancing the discipline of chemical engineering toward ultimate mechanism-based understanding of chemical processes? This possibility is comparatively expounded with other proposals, and the scope and depth of computational chemical engineering are shortly listed.

关键词： Paradigm Unit operations Transport phenomena Chemical product engineering Sustainable chemical engineering Computational chemical engineering Numerical simulation

Power Requirements of Vertical Flight in the Dronefly

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Journal of Bionic Engineering 2015年第2期12卷 227-237页

作者： Chong Shen mao Sun Institute of Fluid Mechanics Beijing University o[Aeronautics & Astronautics Beijing 100191 China

Power requirements in vertical flight in the dronefly （Eristarlis tenax; also known as hoverfly） are studied using the metnoa of computational fluid dynamics. The flow solution provides the aerodynamic forces and torques; the inertial torques due to the acceleration of the wing-mass are computed analytically. From the aerodynamic and inertial torques, the mechanical power is obtained. It has been shown that at hovering flight, the specific power with 100% elastic energy storage is 43.51 *** · and that without elastic energy storage is 60.12 W·kg-1. During vertical flight, the specific power increases with the ascending ratio K （ratio of the ascending velocity to the tip velocity）; it is proportional to K to the power of about 1.37. When flying upward at an ascending ratio of about 0.3, the power required is the same as that when the insect carries a load of about 50% of its weight.

关键词： insect upward flying Navier-Stokes simulation flight balance flight power

Control for going from hovering to small speed flight of a model insect

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Acta Mechanica Sinica 2009年第3期25卷 295-302页

作者： Jianghao Wu mao Sun School of Transportation Science and Engineering Beihang University 100191 Beijing China Institute of Fluid Mechanics Beihang University 100191 Beijing China

The longitudinal steady-state control for going from hovering to small speed flight of a model insect is studied, using the method of computational fluid dynamics to compute the aerodynamic derivatives and the techniques based on the linear theories of stability and control for determining the non-zero equilibrium points. Morphological and certain kinematical data of droneflies are used for the model insect. A change in the mean stroke angle （δФ） results in a horizontal forward or backward flight; a change in the stroke amplitude （δФ） or a equal change in the down- and upstroke angles of attack （δα1） results in a vertical climb or decent; a proper combination of δФ and δФ controls （or δФ and δα1 controls） can give a flight of any （small） speed in any desired direction.

关键词： Insect. Flight control Hovering ,Small speed flight