Experimental study of heat transfer in oscillating flow

This paper describes an experimental study of heat transfer in oscillating flow inside a cylindrical tube. Profiles of temperature are taken inside the wall and in the fluid from an instrumented test rig, in different conditions of oscillating flow. Profiles obtained allow the observation of the wall effect on heat transfer. A method using the inverse heat conduction principle allows the characterization of local heat transfers at the fluid-solid interface. Finally, a comparison between global and local approaches of heat transfer shows the difficulty of defining a dimensionless heat flux density to model local heat transfer in oscillating flow.     

Asymptotic performances of a constructive algorithm

We present a numerical study of a neural tree learning algorithm, the “triolearning≓ strategy. We study the behaviour of the algorithm as a function of the size of the training set. The results show that a limited number of examples can be used to estimate both the network performance and the network complexity that would result from running the algorithm on a large data set.     

The Fermi energy and the enthalpy of mixing

In this paper we describe a new function to determine the number of electrons transferred by alloying. H_F, the new function proposed, is given by the difference of the partial enthalpies of the two constituents, i.e. H_F = h(i) - h(j) - h(i)^o and is called the Fermi enthalpy. It is retrieved from data calorimetrically measured. In some way, it describes the change in the enthalpic part of the Fermi energy on alloying. This function is determined for Pd + Ga, Pd + In, Ni + Ga, Ni + In, Pt + In, Au + Al and Ag + Al. The corresponding number of electrons transferred is calculated on stoichiometric considerations.     

Stimulating Cooperation in Self-Organizing Mobile Ad Hoc Networks

In military and rescue applications of mobile ad hoc networks, all the nodes belong to the same authority; therefore, they are motivated to cooperate in order to support the basic functions of the network. In this paper, we consider the case when each node is its own authority and tries to maximize the benefits it gets from the network. More precisely, we assume that the nodes are not willing to forward packets for the benefit of other nodes. This problem may arise in civilian applications of mobile ad hoc networks. In order to stimulate the nodes for packet forwarding, we propose a simple mechanism based on a counter in each node. We study the behavior of the proposed mechanism analytically and by means of simulations, and detail the way in which it could be protected against misuse.     

Recent developments in fluorescence—based mincroscopy applied in biomedical sciences

1.IntroductionOverthelastfourdecades,fluorescencemicroscopyhasexperiencedatremendousinnovat-ingevolutionandisnowadaysawellestablishedtechniqueinmanyareasofbiomedicalre-search.Inaddition,fluorescencemicroscopicalimaginghasprovenanessentialtoolforstudy-ingbothcellstructureanddynamicprocessestakingplacewithinonecellorbetweenneigh-bouringcells.Thepresentshortreviewwillfocusonthemostrecentdevelopmentsinthisfieldofmicroscopy.2.ConventionalfluorescencemicroscopyTheterm“fluorescence”denotestheprope…     

Hardness, Toughness, and Scratchability of Germanium–Selenium Chalcogenide Glasses

Ge–Se chalcogenide glasses are characterized by relatively low hardness (0.39–2.35 GPa) and low fracture toughness (0.1–0.28 MPa·m^1/2). Actually, the hardness of chalcogen-rich glasses is low enough so that the brittleness parameter, B = H / K _c , is lower than that of silicate glasses. Whereas hardness and Young's modulus increase with increasing germanium contents, fracture toughness follows a trend similar to that of the density and exhibits a maximum for the Ge₂₀Se₈₀ composition, which corresponds to the rigidity percolation threshold. Optical microscopy and atomic force microscopy observations suggest that the indentation deformation proceeds by a localized shear deformation phenomenon. Glasses in the chalcogen-rich region behave viscoelastically at room temperature. As a consequence, an increase of the loading time results in a decrease of hardness and toughness.     

Kinetic study of the sulfurisation of cuprous halides in hydrogen sulfide. Cuprous bromide and iodide

The sulfurisation of cuprous bromides and iodides in hydrogen sulfide, at low pressure, leads to the formation of a porous chalcosine layer, as already investigated in the case of chlorides. The step which fixes the conversion rate is the diffusion of the gaseous reagents in the pores of the sulfide formed. Experimental activation energies are 15 and 34 kcal.Mole^?1 respectively, at every step of the reaction.     

Substitution du tungstene par le tantale dans les bronzes de tungstene NaxTayW1−yO3

In order to study the modification of the transport properties of Na_xWO₃ by substitution in the WO₃ sublattice, single crystals of tantalum-substituted tungsten bronzes of formula Na_xTa_yW_1?yO₃ have been grown by electrolytic reduction of fused Na₂WO₄WO₃Ta₂O₅ mixtures. The lattice constant of their cubic perovskite like structure increases with Ta content. Electric conductivity measurements on Na_xTa_yW_1?yO₃ single crystals characterize a metal-non metal transition when x-y, i.e. the number of d electrons, decreases. This transition seems to be of Anderson type.     

Skin-core structure–fatigue behavior relationships for injection-molded parts of polypropylene. II. Morphology–fatigue behavior relationships

The flexural fatigue properties were studied for PP injection-molded samples of different molecular weight and well-defined skin-core morphology (see Part I). It can be clearly seen that the crack initiation always occurs in the subskin layer of higher macromolecular orientation, and propagates towards the core. The mechanisms of cracking are discussed on the basis of fatigue kinetic data and analytical measurements on the stressed sections. The important influence of processing conditions, essentially holding pressure on the fatigue behavior is illustrated.