A correlation image velocimetry-based study of high-pressure fuel spray tip evolution

A correlation image velocimetry (CIV) technique has been developed to study the evolution of the leading edge, or tip, of isothermal high-pressure fuel sprays. Adaptations of the analysis permit determination of both the average spray tip motion and the spatial distribution of velocity along the spray edge. From these measurements, three distinct regions of the tip’s evolution have been observed and scaling relations developed. Further investigation has revealed significant uniformity in the radial evolution of the spray tip, despite the apparent similarity to turbulent jet flow. Examination of pdfs of the average tip velocity reveals among the many repeatable injection events a significant amount of variability and that this variability extends to regions near the nozzle, implying that among the sources of shot-to-shot viability is the atomisation process itself.     

Sorption of Arsenic Oxyanions from Aqueous Solution on Goethite: a Study of Process Modelling

In the course of researching methods of sampling and monitoring toxic metals (as arsenic ions) in water and wastewaters, we selected the use of sorption for in-depth examination. Among other things, sorption modelling was investigated by the mechanism of surface complexation in order to describe the process or even predict the outcome for the expected rate, and in general, to develop this detection technique for pollutants. This investigation will include the application of goethite mineral as the suitable metal ion sorbent and the use of appropriate computer software. The relative thermodynamic aqueous speciation of the solution, in similar experimental conditions, was also studied.     

Complex potential formalisms for bending of inhomogeneous monoclinic plates including transverse shear deformation

This paper develops complex potential formalisms for the solution of the bending problem of inhomogenoeus anisotropic plates, on the basis of the most commonly used refined plate theories. Being an initial step in that direction, it works out such formalisms only in connection with the bending problem of shear deformable homogeneous plates as well as plates having a special type of inhomogeneity along their thickness direction. The adopted type of inhomogeneity is however still general enough to include certain classes of plates made of functionally graded material as well as the classes of cross- and angle-ply symmetric laminates as particular cases. The basic formalism, similar to that developed by Stroh in plane strain elasticity, is detailed in relation with the equilibrium equations of a generalized plate theory that accounts for the effects of transverse shear deformation and includes conventional, refined theories as particular cases. Some interesting specializations, related to the most important of those conventional plate theories, are then presented and discussed separately. Hence, the outlined formalisms provide, for the first time in analytical form, the general solution of the partial differential equations associated with the most commonly used refined, elastic plate theories.     

On the theories used for the wave propagation in laminated composite thin elastic shells

In this paper, the problem of propagation of free harmonic waves in cross-ply laminated thin elastic shells is considered. For this problem, a theoretical unification of the most commonly used, in physical and engineering applications, thin shell theories which take into consideration transverse shear deformation effects is presented. In more detail, the problem is formulated in such a way that by using some tracers, which have the form of Kronecker's deltas, the obtained stress-strain relations, constitutive equations and equations of motion produce, as special cases, the corresponding relations and equations of the transverse shear deformable analogs of Donnell's, Love's and Sanders' theories. Using an eigenvalue form solution of the equations of motion, a comparison of corresponding numerical results obtained on the basis of all of the afore-mentioned theories is made. Comparisons with corresponding results obtained on the basis of the classical thin shell theories of Donnell, Love, Sanders and Flugge are also made.

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Resumé On étudie un problème de propagation d'ondes harmoniques libres dans une fine coque cylindrique, élastique, composée de lamelles croisées. On présente une unification des théories les plus courantes que les ingénieurs et physiciens appliquent aux problèmes de coques minces sous considération de la déformation due au cisaillement transverse. En détails, le problème est formulé de telle façon qu'en utilisant des opérateurs de trace (sous forme du symbole de Kronecker) les relations obtenues: contrainte-déformation, équations constitutives et équations de mouvement donnent comme cas spéciaux les relations correspondantes et les équations des problèmes analogues (déformation de coques minces par cisaillement transverse) des théories de Donnell, Love et Sanders. En utilisant une solution aux valeurs propres des équations de mouvement, on compare les résultats numériques obtenus grâce aux théories mentionées ci-dessus aux résultats correspondants sur la base des théories classiques de Donnell, Love, Sander et Flugge.

     

Double functionalization of carbon nanotubes for multimodal drug delivery

Multi-walled carbon nanotubes have been covalently functionalized via 1,3-dipolar cycloaddition of azomethine ylides with orthogonally protected amino functions that can be selectively deprotected and subsequently modified with drugs and fluorescent probes.     

On the stability of a compressible Rivlin's cube made of transversely isotropic material

^** Email: kostas.soldatos{at}nottingham.ac.uk This paper considers a unit cube made of a compressible, transverselyisotropic elastic material, with the direction of transverseisotropy being aligned normal to one pair of the cube's faces,and investigates the stability of a dilatation equilibrium stateof that cube, with respect to superposed pure homogeneous deformationswith principal directions parallel to the cube edges. This dilatation,intermediate equilibrium state (state I) of the cube is assumedattainable in two different ways. Accordingly, in what is termedas the ‘principal stability problem’ under investigation,state I is considered to be that of uniform dilatation, whichis attained upon loading normally and uniformly the oppositefaces of the unit cube with certain pairs of equal and oppositelydirected forces having appropriately selected magnitudes. Inwhat is termed as the ‘modified stability problem’under investigation, the same compressible, transversely isotropicunit cube is loaded uniformly by three identical pairs of equaland oppositely directed forces acting normally to its faces,and, hence, it attains in state I the shape of a certain rectangularparallelepiped. The necessary and sufficient conditions forstability of state I of the cube deformation are obtained inthe form of three inequalities, which are found to hold regardlessof whether the intermediate equilibrium state I is that of uniformdilatation or that of the aforementioned rectangular parallelepiped(non-uniform dilatation). These, however, lead to quite differentspecific results and conclusions when applied in connectionwith, first, the principal and, then, the modified stabilityproblem of a unit cube made of a particular type of a transverselyisotropic extension of the Blatz–Ko (isotropic) material.     

Solving multiobjective,multiconstraint knapsack problems using mathematical programming and evolutionary algorithms

In this paper, we solve instances of the multiobjective multiconstraint (or multidimensional) knapsack problem (MOMCKP) from the literature, with three objective functions and three constraints. We use exact as well as approximate algorithms. The exact algorithm is a properly modified version of the multicriteria branch and bound (MCBB) algorithm, which is further customized by suitable heuristics. Three branching heuristics and a more general purpose composite branching and construction heuristic are devised. Comparison is made to the published results from another exact algorithm, the adaptive ε-constraint method [Laumanns, M., Thiele, L., Zitzler, E., 2006. An efficient, adaptive parameter variation scheme for Metaheuristics based on the epsilon-constraint method. European Journal of Operational Research 169, 932–942], using the same data sets. Furthermore, the same problems are solved using standard multiobjective evolutionary algorithms (MOEA), namely, the SPEA2 and the NSGAII. The results from the exact case show that the branching heuristics greatly improve the performance of the MCBB algorithm, which becomes faster than the adaptive ε -constraint. Regarding the performance of the MOEA algorithms in the specific problems, SPEA2 outperforms NSGAII in the degree of approximation of the Pareto front, as measured by the coverage metric (especially for the largest instance).     

Hidden supersymmetry of domain walls and cosmologies

We show that all domain-wall solutions of gravity coupled to scalar fields for which the world-volume geometry is Minkowski or anti-de Sitter admit Killing spinors, and satisfy corresponding first-order equations involving a superpotential determined by the solution. By analytic continuation, all flat or closed Friedmann-Lema?tre-Robertson-Walker cosmologies are shown to satisfy similar first-order equations arising from the existence of "pseudo Killing" spinors.