Search results for " COMPOSITES"
showing 10 items of 1620 documents
Amorphous As–S–Se semiconductor resists for holography and lithography
2002
Abstract The photo- and electron-beam induced changes in solubility of thin films of the amorphous chalcogenide semiconductors As–S–Se and As 2 S 3 have been studied. The possibilities of practical application of these materials as resists for the production of relief holograms and holographic optical elements are discussed. It is shown that the self-enhancement (SE) phenomenon of holographic recording in amorphous chalcogenide semiconductor films by light or thermal treatment can be used to increase the diffraction efficiency (DE) of the holograms.
A modular approach towards functional supramolecular aggregates - subtle structural differences inducing liquid crystallinity.
2016
Herein we report an efficient modular approach to supramolecular functional materials. Hierarchical self-assembly of azopyridine derivatives and hydrogen-bond donors yielded discotic assemblies. Subtle differences in the core units introduced mesomorphic behaviour and fast photo-response of the liquid crystals based on phloroglucinol. The presented results prove the benefits of a modular methodology towards highly responsive materials with tailor-made properties.
SPECTRAL AND TEMPORAL CHARACTERISTICS OF LIQUID CRYSTAL GOGGLES FOR VISION RESEARCH
2008
ABSTRACT Spectral and switching characteristics of two manufacturer liquid crystal goggles are tested. Experimentally the human stereovision acuity and threshold were studied for the case, when one eye random dot stereo stimulus simulated on the display is continuously blurred or the stimulus contrast is decreased. In order to determine the artefacts of two eye channel crosstalk on the stereostimuli separation the contrast ratio limits for the computer display phosphors wavelengths are determined.
Transparent amorphous memory cell: A bipolar resistive switching in ZnO/Pr0.7Ca0.3MnO3/ITO for invisible electronics application
2014
Abstract ZnO/Pr0.7Ca0.3MnO3 (ZnO/PCMO) amorphous thin films were grown on an indium-tin-oxide (ITO)/glass by pulsed laser deposition at room temperature. Interestingly, a stable bipolar resistive switching behavior of the ITO/ZnO/PCMO/ITO cell can be longer than 2.5 × 103 cycles. The on/off ratio of switching behaviors is as high as 104. The structure of ITO/ZnO/PCMO/ITO exhibits a high average transparency of 79.6% in the visible range with a maximum transparency of 84.6% at 590 nm wavelength. The conductive mechanism during switching cycling in our structure can be described by a trapped-control space charge limited current behavior. The ZnO/PCMO/ITO/glass structure shows a potential of t…
Light-induced ionic processes in optical oxide glasses
1991
Abstract The density of optical glasses is changed by the influence of light capable of generating color centers in these materials. Such defect generation is not only an electronic process, but an atomic displacement is also necessary. The strong localization of electronic and vibrational excitations in the glass network leads to the high efficiency of sub-threshold defect generation. Secondary ionic processes lead to the changes of basic glass properties (light refractive index, density, mechanical strength, etc.); thus, it is possible to use optical glasses as light detectors for appropriate wavelengths.
EXPERIMENTAL AND NUMERICAL EVALUATION OF THE MECHANICAL BEHAVIOUR OF GFRP SANDWICH PANELS
2007
This work deals with the analysis of the mechanical behaviour of a class of sandwich structures widely employed in marine constructions, constituted by fiber-glass laminate skins over PVC foam or polyester mat cores. In detail, a systematic experimental study and numerical simulations have shown that the theoretical prediction of the strength and the actual failure mechanism of these sandwich structures can be affected by significant errors, specially in the presence of prevalent shear loading. Moreover, because of the low shear stiffness and the elastic constants mismatch of the skins and core material, failure modes and strength are strongly influenced by eventual stresses orthogonal to t…
Photoinduced mass transport in low molecular organic glasses and its practical application in holography
2015
Abstract In this paper we present the synthesis and optical properties of amorphous low molecular compound 4-((4-(bis(5,5,5-Triphenylpentyl)amino)phenyl)diazenyl)benzoic acid. The surface relief gratings formation by polarization holography method on these thin films (thicknesses are 200–1700 nm) was shown. The dependence of the surface relief modulation on various parameters: recording exposure dose, the polarization state of the recording beams, the grating period and the film thickness of the material was demonstrated. Values of surface tension at the air-film before and after irradiation of the substance by polarized radiation were measured. The efficiency of surface relief formation in…
An Improved Thermal Lamination Model for Analysis of Heat Transfer in Composite Structures
2002
A new thermal lamination model and its associated finite element model are presented for analysis of heat transfer in laminated composite structures. The form of the present model closely resembles that of recent zig-zag sublaminate structural laminate theories. The through-thickness distribution of temperature is assumed to vary linearly within each ply, and continuity of transverse flux at ply interfaces is enforced analytically. Thus, the number of computational degrees-offreedom (DOFs) is made independent of the number of plies in the sublaminate. In its present form, the model contains only two computational DOFs in each sublaminate–the temperature at the top and bottom surface of the…
An all-organic steroid–D–π-A modular design drives ferroelectricity in supramolecular solids and nano-architectures at RT
2011
Confluence of a modular design approach and self-assembly with a 'steroid-D-π-A' module generates spontaneous polarization in solids and for the first time in nano-architectures constituted from organogels, at room temperature (RT).
Tensile behaviour of patch-repaired CFRP laminates
2011
The present study examines the tensile behaviour of composite structures repaired by bonding external patches. Various patches of different stacking sequences placed on both sides of the parent plate were considered. Damage development and the failure process of the repaired plates were analyzed and a parent plate fracture model has been proposed. Optimised patch repairs were calculated by finite element modelling. It was found that high stress concentration along the longitudinal edges of circular patches and/or at the transverse edges of the hole leads to early damage initiation in the parent plate. However, the position of damage initiation and the process of damage progression depend pa…