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Investigations on the Chemical Degradation of Silver Gelatine Prints  [PDF]
Maha Ahmed ALI,Mona Fouad ALI,Mohammed Osama SAKER,Abdel Azez El Bayoumi ABDEL ALEEM
International Journal of Conservation Science , 2012,
Abstract: Photographs are considered composite objects with complex chemical and physical structures. Therefore they are more prone to damage as compared to other objects. Chemical degradation is by far the most common decay form found among photographic collections. This study investigates the chemical degradation of silver gelatin prints (DOP) and the reaction of the image, silver, gelatin, and paper to accelerated aging, to the action of light, and oxidizing gases, in terms of their physical and chemical nature. The test materials used are properly washed and poorly washed grayscale, black-and-white processed images on photographic paper (Black & White Photographic Paper BH 0 Bromofort 6P0661 Tropical from Forte Photochemical Company Vác, Hungary). After exposure, the results were studied by means of visual inspection, amino acid analyzer, Fourier transform infrared and transmission electron microscope. The results were compared with those of the control samples. Our study revealed that the image, silver, gelatin and photographic paper are greatly affected by oxidizing agents and that the effect increased if the photographic prints were inadequately washed at the time of their processing. Furthermore, our results indicated that an increased amount of ammonia and amino acid in the silver gelatin print is a reliable indicator of the degradation of its gelatine emulsion.
Homogenization of Composite Ferromagnetic Materials  [PDF]
Fran?ois Alouges,Giovanni Di Fratta
Mathematics , 2014,
Abstract: Nowadays, nonhomogeneous and periodic ferromagnetic materials are the subject of a growing interest. Actually such periodic configurations often combine the attributes of the constituent materials, while sometimes, their properties can be strikingly different from the properties of the different constituents. These periodic configurations can be therefore used to achieve physical and chemical properties difficult to achieve with homogeneous materials. To predict the magnetic behavior of such composite materials is of prime importance for applications. The main objective of this paper is to perform, by means of Gamma-convergence and two-scale convergence, a rigorous derivation of the homogenized Gibbs-Landau free energy functional associated to a composite periodic ferromagnetic material, i.e. a ferromagnetic material in which the heterogeneities are periodically distributed inside the ferromagnetic media. We thus describe the Gamma-limit of the Gibbs-Landau free energy functional, as the period over which the heterogeneities are distributed inside the ferromagnetic body shrinks to zero.
Genetic Homogenization of Composite Materials
J. Jilkova,Z. Raida,P. Tobola
Radioengineering , 2009,
Abstract: The paper is focused on numerical studies of electromagnetic properties of composite materials used for the construction of small airplanes. Discussions concentrate on the genetic homogenization of composite layers and composite layers with a slot. The homogenization is aimed to reduce CPU-time demands of EMC computational models of electrically large airplanes. First, a methodology of creating a 3-dimensional numerical model of a composite material in CST Microwave Studio is proposed focusing on a sufficient accuracy of the model. Second, a proper implementation of a genetic optimization in Matlab is discussed. Third, an association of the optimization script and a simplified 2-dimensional model of the homogeneous equivalent model in Comsol Multiphysics is proposed considering EMC issues. Results of computations are experimentally verified.
Biomimetic Design and Test of Composite Materials
Benlian ZHOU International Centre for Materials Physics,

材料科学技术学报 , 1993,
Abstract: A series of superior properties will make composites the most important structural materials in the next century.But they are difficult to design owing to the complexity of structure and processing. Biomaterials had been naturally selected and evolved for millions of years,a great variety of their ra- tional composite structures could be taken as our reference in the biomimetic design of composite materials.There are many difficult problems in the current study on composite materials such as: brittleness of continuous fibers and difficulties in interface design;easy pull-out of short fibers from matrix causing failure in reinforcing;being less easy in selecting the aspect ratio of whiskers and dif- ficulties in finding the way of toughening composites of ceramic matrices as well as the way of heal- ing inner damages.After describing the distinct composite features,the functional adaptability and self-healing ability of biomaterials,several examples o.f biomimetic design of composite materials have been listed in this paper:the optimum design of composites simulating bamboo structure;the fine structure of bamboo fibers;the dumb-bell model simulating animal bone;the model on the pull-out of fiber with fractal-tree structure and some tentative works on the healing of inner damage in composite materials The methodology of biomimetic design and its future have been given at the ast part of this paper.
Multi-scale Modeling for Piezoelectric Composite Materials  [PDF]
Qian Zhang,Xingye Yue
Physics , 2014,
Abstract: In this paper, we focus on multi-scale modeling and simulation of piezoelectric composite materials. A multi-scale model for piezoelectric composite materials under the framework of Heterogeneous Multi-scale Method(HMM) is proposed. For materials with periodic microstructure, macroscopic model is derived from microscopic model of piezoelectric composite material by asymptotic expansion. Convergence analysis under the framework of homogenization theory is carried out. Moreover, error estimate between HMM solutions and homogenization solutions is derived. A 3-D numerical example of 1-3 type piezoelectric composite materials is employed to verify the error estimate.
Mechanical properties and the structure of magnetic composite materials
L.A. Dobrzański,B. Zi?bowicz,M. Drak
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: The purpose of the paper is to present the material and technological solution which makes possibleobtaining soft and hard magnetic composite materials: nanocrystalline material – polymer.Design/methodology/approach: The main base of the paper is to compare the structure and mechanicalproperties of chosen magnetic composite materials with polymer matrix reinforced with Nd-Fe-B or FINEMETparticles manufactured by one-sided uniaxal pressing. The complex relationships among the manufacturingtechnology of these materials, their microstructure, as well as their mechanical and physical properties wereevaluated.Findings: Modern magnetic materials have optimum technology of production with properties that allow forminiaturizing, simplification and lowering the costs of devicesPractical implications: The manufacturing of composite materials greatly expands the applicable possibilitiesof nanocrystalline powders of magnetically hard and soft materials however further examination obtainimproved properties of magnetic composite materials. The investigations of constructing of new machines anddevices with these materials elements are still needed.Originality/value: The paper shows the base of the material and technological solution which make possibleobtaining magnetic composite materials and their mechanical properties which are not commonly presented inother papers.
Effect of Interface Structure on Mechanical Properties of Advanced Composite Materials  [PDF]
Yong X. Gan
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10125115
Abstract: This paper deals with the effect of interface structures on the mechanical properties of fiber reinforced composite materials. First, the background of research, development and applications on hybrid composite materials is introduced. Second, metal/polymer composite bonded structures are discussed. Then, the rationale is given for nanostructuring the interface in composite materials and structures by introducing nanoscale features such as nanopores and nanofibers. The effects of modifying matrices and nano-architecturing interfaces on the mechanical properties of nanocomposite materials are examined. A nonlinear damage model for characterizing the deformation behavior of polymeric nanocomposites is presented and the application of this model to carbon nanotube-reinforced and reactive graphite nanotube-reinforced epoxy composite materials is shown.
Derivation of Equivalent Material Models for Composite Laminated Materials
S. Gona,V. Kresalek
Radioengineering , 2009,
Abstract: In this paper, an original approach of derivation of equivalent electrical models for multilayer composite materials is presented. The purpose of the modeling is to approximate a given composite material by an equivalent dielectric slab or by a medium consisting from several dielectric layers. For each layer, an equivalent complex permittivity is set up by an optimization procedure in order to achieve the same values of reflection and transmission coefficients as are the measured values of reflection and transmission coefficients of the original composite material.
Manufacturing of hard magnetic composite materials Nd-Fe-B  [PDF]
M. Drak,B. Zi?bowicz,L.A. Dobrzański
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: This paper presents the material and technological solution which makes it possible obtaining of hard magnetic composite materials: nanocrystalline material – polymer.Design/methodology/approach: For fabrication of composite materials the Nd-Fe-B powder obtained by melt quenching technique was used and for matrix: epoxy resin (EP) or high density polyethylene (HDPE) (2.5 % wt.). Composite materials were compacted by the one-sided uniaxial pressing. The complex relationships among the manufacturing technology of these materials, their microstructure, as well as their properties were evaluated. Materialographic examination of powders morphology and the structure of composite materials were made.Findings: Composite materials show regular distribution of magnetic powder in polymer matrix. Examination of mechanical properties show that these materials have satisfactory compression strength.Research limitations/implications: The advantage of the bonded composite materials is their simple technology, possibility of forming their properties, lowering manufacturing costs because of no costly finishing and lowering of material losses resulting from the possibility of forming any shape. The manufacturing of composite materials greatly expand the applicable possibilities of nanocrystalline powders of magnetically hard materials.Originality/value: Manufacturing processes of hard magnetic composite materials obtaining Nd-Fe-B – polymer matrix.
FEM modelling of magnetostrictive composite materials  [PDF]
L.A. Dobrzański,A. Tomiczek,G. Dziatkiewicz
Archives of Materials Science and Engineering , 2012,
Abstract: Purpose: The paper presents a numerical model for the analysis of magnetostriction in composite materials in polymer matrix reinforced by Tb0.3Dy0.7Fe1.9 particles. The properties were determined by taking into account the applied stresses and magnetic field intensity.Design/methodology/approach: The finite element method for simulation the magnetostriction phenomenon was established by theoretical analysis based on experimental results.Findings: Thanks to the finite element method the numerical model has been formulated, enabling to simulate behavior of dynamically exciting rod with the nonlinear constituted model of magnetostrictive effect. The results received from experiments and simulations confirmed accuracy of this model for operating conditions, enabling a selection of magnetostrictive composite material with polymer matrix reinforced with Tb0.3Dy0.7Fe1.9 particles for specific application.Research limitations/implications: It was confirmed that using the finite element method can be a way for reducing the investigation cost. This paper proposes analysis which is efficient with respect to the number of simplifications in numerical model and accuracy of results.Practical implications: The proposed method could be helpful in the design process of magnetostrictive composite materials.Originality/value: Modelling based on the finite element method allows to simulating behavior of dynamically exciting rod with the nonlinear constituted model of magnetostriction phenomenon.
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