The 7th International Conference on Fluid Mechanics May 24-27,2015,Qingdao,China

正http://www.icfm7.org First Announcement and Call for PapersThe objective of International Conference on Fluid Mechanics(ICFM)is to provide a forum for researchers to exchange new ideas and recent advances in the fields of theoretical,experimental,computational Fluid Mechanics as well as interdisciplinary subjects.It was successfully convened by the Chinese Society of Theoretical and Applied Mechanics(CSTAM)in Beijing(1987,     

INFORMATION FOR CONTRIBUTORS

Contributions： The Journal, Acta Mechanica Solida Sinica, is pleased to receive papers from engineers and scientists working in various aspects of solid mechanics. All contributions are subject to critical review prior to acceptance and publication.     

Preface

This special issue of PARTICUOLOGY is devoted to the first UK-China Particle Technology Forum taking place in Leeds, UK, on 1-3 April 2007. The forum was initiated by a number of UK and Chinese leading academics and organised by the University of Leeds in collaboration with Chinese Society of Particuology, Particle Technology Subject Group （PTSG） of the Institution of Chemical Engineers （IChemE）, Particle Characterisation Interest Group （PCIG） of the Royal Society of Chemistry （RSC） and International Fine Particle Research Institute （IFPRI）. The forum was supported financially by the Engineering and Physics Sciences Research Council （EPSRC） of United Kingdom,     

基于鲁棒滤波的捷联导引头视线角速度估计方法

针对捷联导引头无法直接获取视线角速度等信息的问题,研究了鲁棒滤波在大气层外飞行器捷联导引头视线角速度估计中的应用。为了建立非线性滤波估计模型,考虑目标视线角速度的慢变特性,采用一阶马尔科夫模型建立了状态方程;推导了视线角速度的解耦模型,并建立了量测方程;考虑到实际应用中存在系统噪声统计特性失准的问题,基于Huber-Based鲁棒滤波方法,设计了视线角速度滤波器,并完成了基于Huber-Based滤波方法和扩展卡尔曼滤波方法的数学仿真。仿真结果表明Huber-Based滤波方法的视线角、视线角速度及视线角加速度估计精度分别达到0.1140'、0.1423'/s、0.0203'/s2,而扩展卡尔曼滤波方法的视线角、视线角速度及视线角加速度估计精度仅分别为0.6577'、0.6415'/s、0.0979'/s~2。仿真结果证明了该方法可以有效地估计出相对视线角速度等信息,并且在非高斯噪声的条件下,依然可获得较高的估计精度,具有一定的鲁棒性。     

Guide for authors

正Each of the sections below provides essential information for authors.We recommend that you take the time to read them before submitting a contribution to Acta Mechanica Sinica.We hope our guide to authors may help you navigate to the appropriate section.How to prepare a submission This document provides an outline of the editorial process involved in publishing a scientific paper in Acta Mechanica     

Use specification of multiscale materials for life spanned over macro-, micro-, nano-, and pico-scale

Multiscale material intends to enhance the strength and life of mechanical systems by matching the transmitted spatiotemporal energy distribution to the constituents at the different scale, say—macro, micro, nano, and pico,—, depending on the needs. Lower scale entities are, particularly, critical to small size systems. Large structures are less sensitive to microscopic effects. Scale shifting laws will be developed for relating test data from nano-, micro-, and macro-specimens. The benefit of reinforcement at the lower scale constituents needs to be justified at the macroscopic scale. Filling the void and space in regions of high energy density is considered.Material inhomogeneity interacts with specimen size. Their combined effect is non-equilibrium. Energy exchange between the environment and specimen becomes increasingly more significant as the specimen size is reduced. Perturbation of the operational conditions can further aggravate the situation. Scale transitional functions and/or f_j/j+1 are introduced to quantify these characteristics. They are represented, respectively, by , and (f_mi/ma,f_na/mi,f_pi/na). The abbreviations pi, na, mi, and ma refer to pico, nano, micro and macro.Local damage is assumed to initiate at a small scale, grows to a larger scale, and terminate at an even larger scale. The mechanism of energy absorption and dissipation will be introduced to develop a consistent book keeping system. Compaction of mass density for constituents of size 10⁻¹², 10⁻⁹, 10⁻⁶, 10⁻³ m, will be considered. Energy dissipation at all scales must be accounted for. Dissipations at the smaller scale must not only be included but they must abide by the same physical and mathematical interpretation, in order to avoid inconsistencies when making connections with those at the larger scale where dissipations are eminent.Three fundamental Problems I, II, and III are stated. They correspond to the commonly used service conditions. Reference is made to a Representative Tip (RT), the location where energy absorption and dissipation takes place. The RT can be a crack tip or a particle. At the larger size scales, RT can refer to a region. Scale shifting of results from the very small to the very large is needed to identify the benefit of using multiscale materials.     

Impact non-pénétrant sur le thorax : influence de la courbure sur la propagation des ondesNonpenetrating impact on the thorax: influence of curvature on wave propagation

Theoretical studies of the propagation of impact waves through the thorax are needed to improve the design of bulletproof jackets and blast protections (Fung in ‘Biomechanics Motions, Flow, Stress, and Growth’, Springer-Verlag, 1990; Cooper et al., J. Trauma 40 (1996) S38–S41). The influence of the weak acoustic coupling at the interface between the thoracic wall and the lung were described in (Grimal et al., C. R. Acad. Sci. IIB 329 (2001) 655–662); in this work, we study, within the frame of elastodynamics and with an approximate analytical method, the effects of the curvature of this interface. Results are given in terms of strain energy for the pressure wave, transmitted or converted. Focalisation of energy in the medium representing the lung is important for curvatures measured in humans. To cite this article: Q. Grimal et al., C. R. Mecanique 330 (2002) 569–574.     

Guide for authors

正Each of the sections below provides essential information for authors.We recommend that you take the time to read them before submitting a contribution to Acta Mechanica Sinica.We hope our guide to authors may help you navigate to the appropriate section.How to prepare a submission This document provides an outline of the editorial process involved in publishing a scientific paper in Acta Mechanica Sinica.     

Vérification expérimentale de la relation de réciprocité d'Onsager pour l'électro-osmose et l'électro-filtration dans une argile naturelleExperimental verification of the Onsager's reciprocal relations for electro-osmosis and electro-filtration phenomena on a saturated clay

This Note is devoted to the experimental verification of the Onsager's reciprocal relations in the particular case of electro-osmosis and electro-filtration. A special set up has been designed to carry out the measurements of both the electro-osmotic permeability and the streaming potential. This has been performed by using a natural material i.e., saturated kaolinite. To cite this article: K. Beddiar et al., C. R. Mecanique 330 (2002) 893–898.     

Nonlinear study of the dynamic behavior of a string-beam coupled system under combined excitations

In this paper,the nonlinear dynamic behavior of a string-beam coupled system subjected to external,parametric and tuned excitations is presented.The governing equations of motion are obtained for the nonlinear transverse vibrations of the string-beam coupled system which are described by a set of ordinary differential equations with two degrees of freedom.The case of 1:1 internal resonance between the modes of the beam and string,and the primary and combined resonance for the beam is considered.The method of multiple scales is utilized to analyze the nonlinear responses of the string-beam coupled system and obtain approximate solutions up to and including the second-order approximations.All resonance cases are extracted and investigated.Stability of the system is studied using frequency response equations and the phase-plane method.Numerical solutions are carried out and the results are presented graphically and discussed.The effects of the different parameters on both response and stability of the system are investigated.The reported results are compared to the available published work.     

Cells as strain-cued automata

We argue in favor of representing living cells as automata and review demonstrations that autonomous cells can form patterns by responding to local variations in the strain fields that arise from their individual or collective motions. An autonomous cell's response to strain stimuli is assumed to be effected by internally-generated, internally-powered forces, which generally move the cell in directions other than those implied by external energy gradients. Evidence of cells acting as strain-cued automata have been inferred from patterns observed in nature and from experiments conducted in vitro. Simulations that mimic particular cases of pattern forming share the idealization that cells are assumed to pass information among themselves solely via mechanical boundary conditions, i.e., the tractions and displacements present at their membranes. This assumption opens three mechanisms for pattern formation in large cell populations: wavelike behavior, kinematic feedback in cell motility that can lead to sliding and rotational patterns, and directed migration during invasions. Wavelike behavior among ameloblast cells during amelogenesis (the formation of dental enamel) has been inferred from enamel microstructure, while strain waves in populations of epithelial cells have been observed in vitro. One hypothesized kinematic feedback mechanism, “enhanced shear motility”, accounts successfully for the spontaneous formation of layered patterns during amelogenesis in the mouse incisor. Directed migration is exemplified by a theory of invader cells that sense and respond to the strains they themselves create in the host population as they invade it: analysis shows that the strain fields contain positional information that could aid the formation of cell network structures, stabilizing the slender geometry of branches and helping govern the frequency of branch bifurcation and branch coalescence (the formation of closed networks). In simulations of pattern formation in homogeneous populations and network formation by invaders, morphological outcomes are governed by the ratio of the rates of two competing time dependent processes, one a migration velocity and the other a relaxation velocity related to the propagation of strain information. Relaxation velocities are approximately constant for different species and organs, whereas cell migration rates vary by three orders of magnitude. We conjecture that developmental processes use rapid cell migration to achieve certain outcomes, and slow migration to achieve others. We infer from analysis of host relaxation during network formation that a transition exists in the mechanical response of a host cell from animate to inanimate behavior when its strain changes at a rate that exceeds 10⁻⁴–10⁻³ s⁻¹. The transition has previously been observed in experiments conducted in vitro.     

Tribology and Its Many Facets: From Macroscopic to Microscopic and Nano-scale Phenomena

The key features of tribology – interfacial phenomena of interacting bodies in relative motion – are as origin of friction and wear scientifically interesting and have important applications in technology and engineering. The interfacial interactions have been studied in various theoretical and experimental approaches. Depending on the scope of the investigation and the nature of the tribological solid/fluid/solid or solid/solid system under study, these approaches apply contact mechanics, hydrodynamics, and rheology as well as solid state physics and chemistry. Accordingly, also various experimental techniques have been used, ranging from Coulomb's classical tribometer to the contemporary atomic force microscope.This paper reviews by way of examples some of the basic interfacial facets of tribology – from bulk continuum to atomistic/discrete phenomena – in a macroscopic, microscopic, and nano-scale point of view. For tribo-testing it is important to characterize the tribo-system under study by an appropriate choice of a systems envelope and to consider the hierarchy of interaction levels.     

Evaluating Herschel-Bulkley fluids with the back extrusion (annular pumping) technique

A mathematical model was developed to describe the behavior of Herschel-Bulkley fluids in a back extrusion (annular pumping) device. A technique was also developed to determine the rheological properties (yield stress, flow behavior index, and consistency coefficient) of these fluids. Mathematical terms were expressed in four dimensionless terms, and graphical aids and tables were prepared to facilitate the handling of the expressions.Nomenclature a radius of the plunger, m - dv/dr shear rate, s^–1 - F force applied to the plunger, N - F _b buoyancy force, N - F _cb force corrected for buoyancy, N - F _T recorded force just before the plunger is stopped, N - F _Te recorded force after the plunger is stopped, N - g acceleration due to gravity, m/s² - H(t) momentary height between plunger and container bottom, m - K a/R, dimensionless - L length of annular region, m - L(t) depth of plunger penetration, m - n flow behavior index, dimensionless - p static pressure, Pa - P _L pressure in excess of hydrostatic pressure at the plunger base, Pa - p ₀ pressure at entrance to annulus, Pa - P pressure drop per unit of length, Pa/m - Q total volumetric flow rate through the annulus, m³/s - r radial coordinate, measured from common axis of cylinder forming annulus, m - R radius of outer cylinder of annulus, m - s reciprocal of n, dimensionless - t time, s - T dimensionless shear stress, defined in Eq. (3) - T ₀ dimensionless yield stress, defined in Eq. (4) - T _w dimensionless shear stress at the plunger wall - _p velocity of plunger, m/s - velocity, m/s - mass density of fluid, kg/m³ - Newtonian viscosity, Pa s - P p ₀ –p _L , Pa - consistency coefficient, Pa sⁿ - value of where shear stress is zero - _–, ₊ limits of the plug flow region (Fig. 1) - r/R - shear stress, Pa - _y yield stress, Pa - _w shear stress at the plunger wall, Pa - dimensionless flow rate defined in Eq. (24) - dimensionless velocity defined by Eq. (5) - _–, ₊ dimensionless velocity outside the plug flow region - _max dimensionless maximum velocity in the plug flow region - _p dimensionless velocity at the plunger wall     

Microscale 3D flow mapping with μDDPIV

Three-dimensional (3D) quantitative flow visualization by tracking microscale particles has become an invaluable tool in microfluid mechanics. Defocusing digital particle image velocimetry (DDPIV) can recover spatial coordinates by calculating the separation between defocused images generated by an aperture mask with a plurality of pinholes. In this paper, a high-speed 3D micro-DDPIV (μDDPIV) system was devised based on this technique to achieve microscale velocity field measurements. A micro-volume of 400 × 300 μm² with a depth of 150 μm has been mapped using an inverted microscope equipped with a 20× objective lens. The proposed technique was successfully applied to 3D tracking of 2-μm fluorescent particles inside an evaporating water droplet.     

Methode zum Messen des Langzeitverhaltens von Thermoplasten

Zusammenfassung Es wird eine neue berührungslose optische Dehnungsmeßeinrichtung für biaxiale Langzeit-Zug- bzw. Torsionsversuche vorgestellt. Die Ergebnisse der Versuche an kugel- und kurzglasfasergefülltem Polyamid 6 (PA6) zeigen, daß dieses System genügend genau arbeitet. Das untersuchte Material weist sowohl im Zugversuch als auch im Torsionsversuch nichtlineares Verhalten auf. Bei überlagerten Zug/Torsions-Belastungen verschieben sich die Dehnungen, verglichen mit denen bei gleicher einaxialer Last zu höheren Werten. Durch die Füllstoffzugabe ergeben sich unterschiedliche Verstärkungseffekte. Die faserverstärkten Proben sind erwartungsgemäß eher in Richtung der Rohrachse verstärkt, während das kugelgefüllte System eine höhere Verstärkungswirkung bei Torsionsbelastung erkennen läßt.

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A new optical device for strain measurement in long-term tension and torsion tests is presented. The new system has been compared with others and the results of the experiments with glass bead and short, glas-fiber-filled Polyamid 6 show that it works well. With a dead-weight loading machine used it is possible to perform combined tension/torsion creep experiments or simple tension and simple torsion tests. The materials under consideration here exhibit nonlinear behavior in tension as well as in torsion tests. Under combined loading, which is tensile stress with a superimposed torsional stress, or vice versa, the amounts of the strains compared with those of the one-dimensional stress state are increasing. The fillers produce different reinforcement effects. The bead-filled system is stiffer when subjected to a torsional load, which may be explained by different load carrying mechanism in tension and torsion. The glassfiber-filled system is stiffer in axis direction, because the fibers are aligned to a considerable extent by the flow of the melt during molding.

Vortrag gehalten auf der Jahrestagung der Deutschen Rheologischen Gesellschaft, TH Darmstadt, 19.–21. 4. 1989.     

Methode zum Messen des Langzeitverhaltens von Thermoplasten

Zusammenfassung Es wird eine neue berührungslose optische Dehnungsmeßeinrichtung für biaxiale Langzeit-Zug- bzw. Torsionsversuche vorgestellt. Die Ergebnisse der Versuche an kugel- und kurzglasfasergefülltem Polyamid 6 (PA 6) zeigen, daß dieses System genügend genau arbeitet. Das untersuchte Material weist sowohl im Zugversuch als auch im Torsionsversuch nichtlineares Verhalten auf. Bei überlagerten Zug/Torsions-Belastungen verschieben sich die Dehnungen, verglichen mit denen bei gleicher einaxialer Last zu höheren Werten. Durch die Füllstoffzugabe ergeben sich unterschiedliche Verstärkungseffekte. Die faserverstärkten Proben sind erwartungsgemäß eher in Richtung der Rohrachse verstärkt, während das kugelgefüllte System eine höhere Verstärkungswirkung bei Torsionsbelastung erkennen läßt.

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A new optical device for strain measurement in long-term tension and torsion tests is presented. The new system has been compared with others and the results of the experiments with glass bead and short, glas-fiber-filled Polyamid 6 show that it works well. With a dead-weight loading machine used it is possible to perform combined tension/torsion creep experiments or simple tension and simple torsion tests. The materials under consideration here exhibit nonlinear behavior in tension as well as in torsion tests. Under combined loading, which is tensile stress with a superimposed torsional stress, or vice versa, the amounts of the strains compared with those of the one-dimensional stress state are increasing. The fillers produce different reinforcement effects. The bead-filled system is stiffer when subjected to a torsional load, which may be explained by different load carrying mechanism in tension and torsion. The glass-fiber-filled system is stiffer in axis direction, because the fibers are aligned to a considerable extent by the flow of the melt during molding.

Vortrag gehalten auf der Jahrestagung der Deutschen Rheologischen Gesellschaft, TH Darmstadt, 19.–21. 4. 1989.