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81.
In the current study a meshfree Lagrangian particle method for the Landau–Lifshitz Navier–Stokes (LLNS) equations is developed. The LLNS equations incorporate thermal fluctuation into macroscopic hydrodynamics by the addition of white noise fluxes whose magnitudes are set by a fluctuation–dissipation theorem. The study focuses on capturing the correct variance and correlations computed at equilibrium flows, which are compared with available theoretical values. Moreover, a numerical test for the random walk of standing shock wave has been considered for capturing the shock location. 相似文献
82.
The present paper deals with the variational approach for solving a clamped rectangular plate under a uniform load. The increasing use of composite materials for plate-type structures intensified the need for solutions of rectangular plates. The variational approach has a broad range of applications in solid mechanics. The methods used to solve the problem consider the minimum total potential energy approach. The maximum deflection is obtained for a square plate by the Ritz, Galerkin and Kantorovich methods. The aim of this paper is to find an approximate solution of higher accuracy. Numerical results for various components of stresses are found and plotted in the form of curves. The results obtained by various methods are compared with those reported earlier. The results show reasonable agreement with the known results, but with a simple and practical approach. The physical aspect of the concept is the immediate use of these results in solid and structural mechanics. 相似文献
83.
Ashesh K. Sinha W.J. Zhang M.K. Tiwari 《Engineering Applications of Artificial Intelligence》2012,25(8):1628-1643
This article is betrothed to serve as a continuation of the emerging swarm techniques to solve supply chain problems. Our aim is to map some of the pressing research challenges contributed by the artificial intelligence community and to develop an improved algorithm: Co-evolutionary immuno-particle swarm optimisation with penetrated hyper-mutation (COIPSO-PHM). In this paper, we proposed a new algorithm which uses clonal selection approach in particle swarm optimisation by embedding co-evolutionary theory to solve the problem of inventory replenishment in distributed plant–warehouse–retailer system. Constraint handling is explicitly taken care by implanting augmented lagrangian concept. To demonstrate the efficiency of the algorithm, its performance are evaluated and compared on 10 benchmarked problems (made constrained problem via random initialisation in the infeasible zone) including functions with uni-modalities as well as multi-modalities. The result follows shows superior performance of the algorithm in every respect. 相似文献
84.
Reinhard Miller Dmitri Grigoriev Jürgen Krägel Alexander V. Makievski Valentin B. Fainerman Volodymyr I. Kovalchuk Libero Liggieri Francesca Ravera Michele Ferrari Eva Santini Giuseppe Loglio Victoria Dutschk Thodoris Karapantsios 《Microgravity science and technology》2006,18(3-4):104-107
The utilisation of particle-surfactants nanostructures as stabilising agents represents today the technologic and scientific frontier in the stabilisation of liquid films in emulsion and foams. This topic will be addressed by the proposal STEFAN (STabilisation of Emulsions and FoAms by Nanoparticles), proposed by European groups in the framework of the ESA AO-2004 for Life and Physical Sciences and Applied Research projects Similarly to what can be observed for surfactant-stabilised emulsions and foams, microgravity provides ideal conditions for the investigation of the hierarchy of involved objects: interfacial layer, liquid film, dispersed systems foam or emulsion. Microgravity experiments are planned by refurbishing the Experimental Container FASES for the ISS Fluid Science Laboratory and the facility FASTER for the European Drawer Rack, already under development in existing research programmes. Here the scientific guidelines of the project are presented together with examples and preliminary results on the effect of nano-particle-surfactant structures adsorbed at liquid interfaces. First experimental results have been achieved for particle monolayers at the water/air interface and a thermodynamic model was derived to describe the obtained surface pressure-area isotherms. 相似文献
85.
Ekkehard Krüger 《Journal of Superconductivity and Novel Magnetism》2005,18(4):433-454
The symmetry of the Bloch functions in the conduction band of tetragonal and orthorhombic La2CuO4 is examined for the existence of symmetry-adapted and optimally localizable (usual or spin-dependent) Wannier functions.
It turns out that such Wannier functions do not exist in the tetragonal phase. In the orthorhombic phase, on the other hand,
the Bloch functions can be unitarily transformed in three different ways into optimally localizable Wannier functions: they
can be chosen to be adapted to each of the three phases observed in the pure or doped material, that is, to the antiferromagnetic
phase, to the superconducting phase or to the phase evincing neither magnetism nor superconductivity. This group-theoretical
result is proposed to be interpreted within a nonadiabatic extension of the Heisenberg model. Within this model, atomic-like
states represented by these Wannier functions are responsible for the stability of each of the three phases. However, all
the three atomic-like states cannot exist in the tetragonal phase, but are stabilized by the orthorhombic distortion of the
crystal. A simple model is proposed which may explain the physical properties of La2−x
Sr
x
CuO4 as a function of the Sr concentrationx. 相似文献
86.
G. Loglio P. Pandolfini R. Miller A. Makievski J. Krägel F. Ravera L. Liggieri 《Microgravity science and technology》2005,16(1-4):205-209
The experiments are aimed at the study of the interfacial dilational properties, under microgravity conditions. The examined systems are aqueous solutions of the surfactant n-dodecyl-dimethylphosphine oxide, at different concentrations and temperatures. Low frequency harmonic disturbances are imposed to the interfacial area of an air bubble. Also square pulse disturbances are imposed to each studied system. The experimental results grant information about the dynamics of air-liquid single interfaces. 相似文献
87.
Alexander V. Makievski Volodymyr I. Kovalchuk Jürgen Krägel Madine Simoncini Libero Liggieri M. Ferrari Piero Pandolfini Giuseppe Loglio Reinhard Miller 《Microgravity science and technology》2005,16(1-4):215-218
The present work shows the first experimental and theoretical results for investigations on the rheology of liquid films. The experiments are planned to be performed under microgravity conditions. This environment will allow forming films of different thickness, which is impossible under ground conditions due to drainage. Then the films are forced to harmonic oscillations of the film area so that the film elasticity can be measured as a function of frequency. The presented theoretical model demonstrates the main relationships to be solved under corresponding boundary conditions 相似文献
88.
A study on fitness-for-service assessment for crack-like defects and corrosion in nuclear reactor pressure tubes 总被引:1,自引:0,他引:1
Rakesh Sehgal Ashutosh Tiwari Vivek Sood 《Reliability Engineering & System Safety》2005,89(2):227-235
This paper looks forward to thoroughly assess zirconium alloy (Zr-2) pressure tubes used in nuclear power reactors for crack like and corrosion type defects. It emphasizes on the use of reliability concept for determining the probability of failure of zirconium alloy pressure tubes based on deuterium ingress. The in depth analysis carried out to calculate the reliability index for the above two problems is based on FORM approach. A steady state corrosion rate is assumed to estimate the growth in the dimensions of corrosion defects. The methodology suggested in this paper is useful for designers and plant engineers in timely detection of the cracks and leaks in the pressure tubes used in nuclear reactors and initiate suitable corrective actions based on their criticality. 相似文献
89.
A database model for object dynamics 总被引:1,自引:0,他引:1
M.P. Papazoglou B.J. Krämer 《The VLDB Journal The International Journal on Very Large Data Bases》1997,6(2):73-96
To effectively model complex applications in which constantly changing situations can be represented, a database system must
be able to support the runtime specification of structural and behavioral nuances for objects on an individual or group basis.
This paper introduces the role mechanism as an extension of object-oriented databases to support unanticipated behavioral
oscillations for objects that may attain many types and share a single object identity. A role refers to the ability to represent
object dynamics by seamlessly integrating idiosyncratic behavior, possibly in response to external events, with pre-existing
object behavior specified at instance creation time. In this manner, the same object can simultaneously be an instance of
different classes which symbolize the different roles that this object assumes. The role concept and its underlying linguistic
scheme simplify the design requirements of complex applications that need to create and manipulate dynamic objects.
Edited by D. McLeod / Received March 1994 / Accepted January 1996 相似文献
90.
By investigating the second-order statistics of Gabor wavelet responses derived from natural images, we show that collinearity and parallelism are conspicuous relations. We give a precise mathematical characterization of these Gestalt principles by the conditional probability of two responses. Essential for our investigations is a non-linear transformation, initially utilized within the object recognition system [5], which transforms continuous Gabor wavelet responses into a binary code indicating the presence or absence of local oriented line segments. 相似文献