WorldWideScience

Sample records for base composition

  1. INVOLUTIVE BASES UNDER COMPOSITION

    Institute of Scientific and Technical Information of China (English)

    Zailiang TANG

    2007-01-01

    In this paper, the behaviors of involutive bases under composition operation are studied.For two kinds of involutive bases, i.e., Pommaret bases, Janet bases, we study their behavior problems under composition. Some further problems are also proposed.

  2. REST based service composition

    DEFF Research Database (Denmark)

    Grönvall, Erik; Ingstrup, Mads; Pløger, Morten;

    2011-01-01

    This paper presents an ongoing work developing and testing a Service Composition framework based upon the REST architecture named SECREST. A minimalistic approach have been favored instead of a creating a complete infrastructure. One focus has been on the system's interaction model. Indeed, an ai...

  3. Al - BASED CAST COMPOSITES

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Yadav

    2011-08-01

    Full Text Available The economy is very important feature nowadays in themarket. The researches are playing an important role inengineering field to increase the life of machine parts /components and decrease the cost. The compositematerials have the potential to replace widely used steeland aluminium due to their good characteristics withbetter performance. The Al-based composites have foundextensive applications in automobile industries andaerospace industries due to their increased stiffness,strength, thermal conductivity and wear resistanceproperties. A number of particulate phases have beenemployed in the Al-alloy matrix. The cast aluminiumceramicparticulate composites are finding applications inpistons, connecting rods, cylinder liner, engine cylinderblock, electrical contacts etc.The present investigation isbased on study of the effect of particulate phase on theSEM study, micro-hardness, elastic modulus, tensilestrength and the wear behaviour of Al-5 % SiC-7 % Fe,Al-10 % SiC-6 % Fe and Al-15 % SiC-5 % Fe composites.

  4. Zirconium diboride-based composites

    Energy Technology Data Exchange (ETDEWEB)

    Monteverde, F.; Dalle Fabbriche, D.; Bellosi, A. [CNR-IRTEC, Faenza (Italy). Research Inst. for Ceramics Technology

    2002-07-01

    Two zirconium diboride-based composites were produced and characterised. The starting compositions (wt%) were: 55ZrB{sub 2} + 41TiB{sub 2} + 4Ni and 83ZrB{sub 2} + 13B{sub 4}C + 4Ni. Microstructure, mechanical and physical properties of the hot pressed composites were studied. In both the cases, the nickel introduced as sintering aid promoted the densification during sintering. (orig.)

  5. INTELLIGENT MATERIALS BASED ON CERAMIC COMPOSITES

    OpenAIRE

    Maximov, Y.; Merzlikin, V.; Sidorov, O.; Suttugin, V.

    2010-01-01

    The paper examines the possibility to design intellectual materials based on film composites. Ferroelectric composites are offered to use as the film composites. The authors discuss ferroelectric composites of different structures. Sensors and intellectual materials on the basis of the obtained composites are considered.

  6. Polymer compositions based on PXE

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jin; Eitouni, Hany Basam; Singh, Mohit

    2015-09-15

    New polymer compositions based on poly(2,6-dimethyl-1,4-phenylene oxide) and other high-softening-temperature polymers are disclosed. These materials have a microphase domain structure that has an ionically-conductive phase and a phase with good mechanical strength and a high softening temperature. In one arrangement, the structural block has a softening temperature of about 210.degree. C. These materials can be made with either homopolymers or with block copolymers.

  7. Silicon-based nanoenergetic composites

    Energy Technology Data Exchange (ETDEWEB)

    Asay, Blaine [Los Alamos National Laboratory; Son, Steven [PURDUE UNIV; Mason, Aaron [PURDUE UNIV; Yarrington, Cole [PURDUE UNIV; Cho, K Y [PURDUE UNIV; Gesner, J [PSU; Yetter, R A [PSU

    2009-01-01

    Fundamental combustion properties of silicon-based nano-energetic composites was studied by performing equilibrium calculations, 'flame tests', and instrumented burn-tube tests. That the nominal maximum flame temperature and for many Si-oxidizer systems is about 3000 K, with exceptions. Some of these exceptions are Si-metal oxides with temperatures ranging from 2282 to 2978 K. Theoretical maximum gas production of the Si composites ranged from 350-6500 cm{sup 3}/g of reactant with NH{sub 4}ClO{sub 4} - Si producing the most gas at 6500 cm{sup 3}/g and Fe{sub 2}O{sub 3} producing the least. Of the composites tested NH{sub 4}ClO{sub 4} - Si showed the fastest burning rates with the fastest at 2.1 km/s. The Si metal oxide burning rates where on the order of 0.03-75 mls the slowest of which was nFe{sub 2}O{sub 3} - Si.

  8. Magnetoelectric Composite Based Microwave Attenuator

    Science.gov (United States)

    Tatarenko, A. S.; Srinivasan, G.

    2005-03-01

    Ferrite-ferroelectric composites are magnetoelectric (ME) due to their response to elastic and electromagnetic force fields. The ME composites are characterized by tensor permittivity, permeability and ME susceptibility. The unique combination of magnetic, electrical, and ME interactions, therefore, opens up the possibility of electric field tunable ferromagnetic resonance (FMR) based devices [1]. Here we discuss an ME attenuator operating at 9.3 GHz based on FMR in a layered sample consisting of lead magnesium niobate-lead titanate bonded to yttrium iron garnet (YIG) film on a gadolinium gallium garnet substrate. Electrical tuning is realized with the application of a control voltage due to ME effect; the shift is 0-15 Oe as E is increased from 0 to 3 kV/cm. If the attenuator is operated at FMR, the corresponding insertion loss will range from 25 dB to 2 dB. 1. S. Shastry and G. Srinivasan, M.I. Bichurin, V.M. Petrov, A.S. Tatarenko. Phys. Rev. B, 70 064416 (2004). - supported by grants the grants from the National Science Foundation (DMR-0302254), from Russian Ministry of Education (Å02-3.4-278) and from Universities of Russia Foundation (UNR 01.01.026).

  9. Graphene-based Composite Materials

    Science.gov (United States)

    Rafiee, Mohammad Ali

    We investigated the mechanical properties, such as fracture toughness (KIc), fracture energy (GIc), ultimate tensile strength (UTS), Young¡¦s modulus (E), and fatigue crack propagation rate (FCPR) of epoxy-matrix composites with different weight fractions of carbon-based fillers, including graphene platelets (GPL), graphene nanoribbons (GNR), single-walled carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT), and fullerenes (C60). Only ˜0.125 wt.% GPL was found to increase the KIc of the pure epoxy by ˜65% and the GIc by ˜115%. To get similar improvement, CNT and nanoparticle epoxy composites required one to two orders of magnitude greater weight fraction of nanofillers. Moreover, ˜0.125% wt.% GPL also decreased the fatigue crack propagation rate in the epoxy by ˜30-fold. The E value of 0.1 wt.% GPL/epoxy nanocomposite was ˜31% larger than the pure epoxy while there was only an increase of ˜3% for the SWNT composites. The UTS of the pristine epoxy was improved by ˜40% with GPLs in comparison with ˜14% enhancement for the MWNTs. The KIc of the GPL nanocomposite enhanced by ˜53% over the pristine epoxy compared to a ˜20% increase for the MWNT-reinforced composites. The results of the FCPR tests for the GPL nanocomposites showed a different trend. While the CNT nanocomposites were not effective enough to suppress the crack growth at high values of the stress intensity factor (DeltaK), the reverse behavior is observed for the GPL nanocomposites. The advantage of the GPLs over CNTs in terms of mechanical properties enhancement is due to their enormous specific surface area, enhanced adhesion at filler/epoxy interface (because of the wrinkled surfaces of GPLs), as well as the planar structure of the GPLs. We also show that unzipping of MWNTs into graphene nanoribbons (GNRs) enhances the load transfer effectiveness in epoxy nanocomposites. For instance, at ˜0.3 wt.% of fillers, the Young's modulus (E) of the epoxy nanocomposite with GNRs increased

  10. GPU-based composite subdivision

    Institute of Scientific and Technical Information of China (English)

    LI Guiqing; ZHANG ,liahua; LIANG Cheng; YIN Mengxiao; XIONG Yunhui

    2012-01-01

    This paper proposes a novel strategy based on fragment meshes of Shiue et al. for GPU rendering of compos- ite subdivision surfaces. Two enumeration systems are established to label the primitives of each fragment mesh. A sector-layer-index enumeration system is responsible for retrieving proximities for subdivision masks while a sec- tor-index enumeration system designates a 2D texture buffer in GPU. Recurring to the free conversion between them, our approach may get rid of lookup tables that are designed to record subdivision masks. In addition, relatively small composite subdivision masks make it easy to develop automatically retrieving techniques. Finally, as center vertices are often irregular, their computation is related to an average with alterable number of items. Considering that variable loop is not efficient in GPU, we evaluate the center vertex of each fragment mesh using the linear combination of its level 0, level 1 and limit positions instead of averaging schemes. Experiments demonstrate that our approach generally outper- forms that of Shiue et al. in FPS by a long way.

  11. Estimating Decision Indices Based on Composite Scores

    Science.gov (United States)

    Knupp, Tawnya Lee

    2009-01-01

    The purpose of this study was to develop an IRT model that would enable the estimation of decision indices based on composite scores. The composite scores, defined as a combination of unidimensional test scores, were either a total raw score or an average scale score. Additionally, estimation methods for the normal and compound multinomial models…

  12. Ceria Based Composite Membranes for Oxygen Separation

    DEFF Research Database (Denmark)

    Gurauskis, Jonas; Ovtar, Simona; Kaiser, Andreas;

    2014-01-01

    under the large oxygen potential gradients at elevated temperatures is decisive for the future applications. The gadolinium doped cerium oxide (CGO) based composite membranes are considered as promising candidates due to inherent stability of CGO phase. The CGO matrix is a main oxygen ion transporter......; meanwhile the primary role of a secondary phase in this membrane is to compensate the low electronic conductivity of matrix at intended functioning conditions. In this work thin film (15-20 μm) composite membranes based on CGO matrix and LSF electronic conducting phase were fabricated and evaluated....... Composite thin film was deposited on tubular structural support made of porous MgO phase. Porous CGO layers (20 μm) were implemented as backbones for catalytic phase on both sides of a composite membrane (Fig. 1). During initial trials, the catalytic phase free CGO/LSF composite membranes demonstrated...

  13. Tantalum-Based Ceramics for Refractory Composites

    Science.gov (United States)

    Stewart, David A.; Leiser, Daniel; DiFiore, Robert; Kalvala, Victor

    2006-01-01

    A family of tantalum-based ceramics has been invented as ingredients of high-temperature composite insulating tiles. These materials are suitable for coating and/or permeating the outer layers of rigid porous (foam-like or fibrous) ceramic substrates to (1) render the resulting composite ceramic tiles impervious to hot gases and (2) enable the tiles to survive high heat fluxes at temperatures that can exceed 3,000 F ( 1,600 C).

  14. Composites Similarity Analysis Method Based on Knowledge Set in Composites Quality Control

    OpenAIRE

    Li Haifeng

    2016-01-01

    Composites similarity analysis is an important link of composites review, it can not only to declare composites review rechecking, still help composites applicants promptly have the research content relevant progress and avoid duplication. This paper mainly studies the composites similarity model in composites review. With the actual experience of composites management, based on the author’s knowledge set theory, paper analyzes deeply knowledge set representation of composites knowledge, impr...

  15. Policies Composition Based on Data Usage Context

    OpenAIRE

    Soto-Mendoza, Valeria; Serrano-Alvarado, Patricia; Desmontils, Emmanuel; Garcia-Macias, Jose Antonio

    2015-01-01

    In federated query processing, different datasets can be queried simultaneously. Each dataset has different privacy policies attached, but,which privacy policy will govern the usage of the query result? In this work we propose a mechanism, based on semantic web technologies, tocompose privacy policies. The originality of our approach is that our composition rules are based on the data usage context and deduced implicitterms.

  16. PVA Based Composites with Natural Fillers

    OpenAIRE

    Dzene, A; Geisari, N; Laka, M; Tupureina, V

    2008-01-01

    Poly (vinyl alcohol) (PVA) is recognized as one of the very few vinyl polymers soluble in water also susceptible of ultimate biodegradation in the presence of suitably acclimated microorganisms. Accordingly, increasing attention is devoted to the preparation of environmentally compatible PVA-based materials for a wide range of applications. Several composite blends based on PVA (0.8-2.0 wt% acetate groups) were prepared and characterized.

  17. Stratospheric composition from balloon based measurements

    Energy Technology Data Exchange (ETDEWEB)

    Mencaraglia, F.; Carli, B. [Ist. per le Ricerche sulle Onde Elettromagnetiche, Firenze (Italy); Bonetti, A.; Ciarpallini, P. [Univ. di Firenze (Italy); Carlotti, M.; Lepri, G. [Univ. di Bologna (Italy); Alboni, F.; Cortesi, U.; Ridolfi, M. [Fondazione per la Metereologia Applicata, Firenze (Italy)

    1995-12-31

    Measurements of the composition of the earth`s atmosphere is of fundamental importance for the study of atmospheric chemistry and for developing models that can predict the evolution of the atmosphere itself. Here, the chemical composition of the lower stratosphere has been measured using a polarizing interferometer operating in the far infrared and submillimetric spectral region. The instrument was flown three times (in 1992, 1993 and 1994) from the NSBF balloon base (Fort Sumner, New Mexico) in coincidence with overpasses of the UARS satellite, for a total of about 50 hours of measurements. In this paper the authors report some of the results obtained from the data analysis made up to now.

  18. Fermentation based carbon nanotube multifunctional bionic composites

    OpenAIRE

    Luca Valentini; Silvia Bittolo Bon; Stefano Signetti; Manoj Tripathi; Erica Iacob; Pugno, Nicola M.

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extr...

  19. Fermentation based carbon nanotube bionic functional composites

    OpenAIRE

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique mechanical and physical properties that are not produced by abiotic processes. Based on grape must and bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at r...

  20. Soy-based fillers for thermoset composites

    Science.gov (United States)

    Watt, Paula

    Considerable work has been done with bio-based fillers in thermoplastics. Wood dust has been used for decades in wood plastic composites in conjunction with recycled high HDPE and PET. In recent years rapidly renewable fillers derived from dried distillery grains and from wood have been introduced commercially for thermoset polymers. These fillers provide bio-content and weight reduction to thermoset molding compounds but issues with moisture absorption and polymerization inhibition have limited their commercial acceptance. The intent of this research was to develop a bio-based filler suitable for thermoset composites. This filler would provide a low density alternative to mined mineral filler, such as CaCO3 or clay. Composites made with these fillers would be lighter in weight, which is desirable for many markets, particularly transportation. Cost parity to the mineral fillers, on a volume basis, was desirable and the use of green chemistry principles was a key objective of the project. This work provides a basis from which further development of modified soy flours as fillers for thermoset composites will continue. Biomass has been evaluated as fillers for thermoset composites since the early 1980s but failed to gain commercial acceptance due to excessive water absorption and inhibition issues with free radical curing. Biomass, with a large percentage of carbohydrates, are very hydrophilic due to their abundance of hydroxyl groups, while biomass, high in lignin, resulted in inhibition of the free radical cure of the unsaturated styrenated polyester matrix systems. Generally protein use as a filler is not desirable due to its food value. Torrefaction has proved to be a good, cost effective, process to reduce hydrophilicity of high cellulose feedstock. Surprising, however, some levels of torrefaction were found to induce the inhibition effect of the filler. Scientific inquiry into this problem proved that aromatics form during the torrefaction process and can

  1. Fermentation based carbon nanotube multifunctional bionic composites

    Science.gov (United States)

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-06-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal.

  2. Fermentation based carbon nanotube multifunctional bionic composites

    Science.gov (United States)

    Valentini, Luca; Bon, Silvia Bittolo; Signetti, Stefano; Tripathi, Manoj; Iacob, Erica; Pugno, Nicola M.

    2016-01-01

    The exploitation of the processes used by microorganisms to digest nutrients for their growth can be a viable method for the formation of a wide range of so called biogenic materials that have unique properties that are not produced by abiotic processes. Here we produced living hybrid materials by giving to unicellular organisms the nutrient to grow. Based on bread fermentation, a bionic composite made of carbon nanotubes (CNTs) and a single-cell fungi, the Saccharomyces cerevisiae yeast extract, was prepared by fermentation of such microorganisms at room temperature. Scanning electron microscopy analysis suggests that the CNTs were internalized by the cell after fermentation bridging the cells. Tensile tests on dried composite films have been rationalized in terms of a CNT cell bridging mechanism where the strongly enhanced strength of the composite is governed by the adhesion energy between the bridging carbon nanotubes and the matrix. The addition of CNTs also significantly improved the electrical conductivity along with a higher photoconductive activity. The proposed process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those on strain or light sensors that could sense damage or convert light stimulus in an electrical signal. PMID:27279425

  3. Track Based Alignment of Composite Detector Structures

    CERN Document Server

    Karimäki, V; Schilling, F P

    2006-01-01

    An iterative algorithm for track based alignment is presented. The algorithm can be applied to rigid composite detector structures or to individual modules. The iterative process involves track reconstruction and alignment, in which the chi-2 function of the hit residuals of each alignable object is minimized. Six alignment parameters per structure or per module, three for location and three for orientation, can be computed. The method is computationally light and easily parallelizable. The performance of the method is demonstrated with simulated tracks in the CMS pixel detector and tracks reconstructed from experimental data recorded with a test beam setup.

  4. Correlation between Composition and Properties of Composite Material Based on Scrap Tires

    OpenAIRE

    Mālers, L; Plēsuma, R; Ločmele, L; Kalniņš, M

    2010-01-01

    Purpose of present work is to investigate mechanical and insulation properties of the composite material based on scrap tires and polyurethane-type binder in correlation with composition of composite material. The studies of material’s hardness must be considered as an express-method for estimation of the selected mechanical properties (E and ccompressive stress) of the composite material without direct experimental testing of given parameters. It was shown that composite material must be r...

  5. Spectrally based mapping of riverbed composition

    Science.gov (United States)

    Legleiter, Carl J.; Stegman, Tobin K.; Overstreet, Brandon T.

    2016-07-01

    Remote sensing methods provide an efficient means of characterizing fluvial systems. This study evaluated the potential to map riverbed composition based on in situ and/or remote measurements of reflectance. Field spectra and substrate photos from the Snake River, Wyoming, USA, were used to identify different sediment facies and degrees of algal development and to quantify their optical characteristics. We hypothesized that accounting for the effects of depth and water column attenuation to isolate the reflectance of the streambed would enhance distinctions among bottom types and facilitate substrate classification. A bottom reflectance retrieval algorithm adapted from coastal research yielded realistic spectra for the 450 to 700 nm range; but bottom reflectance-based substrate classifications, generated using a random forest technique, were no more accurate than classifications derived from above-water field spectra. Additional hypothesis testing indicated that a combination of reflectance magnitude (brightness) and indices of spectral shape provided the most accurate riverbed classifications. Convolving field spectra to the response functions of a multispectral satellite and a hyperspectral imaging system did not reduce classification accuracies, implying that high spectral resolution was not essential. Supervised classifications of algal density produced from hyperspectral data and an inferred bottom reflectance image were not highly accurate, but unsupervised classification of the bottom reflectance image revealed distinct spectrally based clusters, suggesting that such an image could provide additional river information. We attribute the failure of bottom reflectance retrieval to yield more reliable substrate maps to a latent correlation between depth and bottom type. Accounting for the effects of depth might have eliminated a key distinction among substrates and thus reduced discriminatory power. Although further, more systematic study across a broader range

  6. Spectrally based mapping of riverbed composition

    Science.gov (United States)

    Legleiter, Carl; Stegman, Tobin K.; Overstreet, Brandon T.

    2016-01-01

    Remote sensing methods provide an efficient means of characterizing fluvial systems. This study evaluated the potential to map riverbed composition based on in situ and/or remote measurements of reflectance. Field spectra and substrate photos from the Snake River, Wyoming, USA, were used to identify different sediment facies and degrees of algal development and to quantify their optical characteristics. We hypothesized that accounting for the effects of depth and water column attenuation to isolate the reflectance of the streambed would enhance distinctions among bottom types and facilitate substrate classification. A bottom reflectance retrieval algorithm adapted from coastal research yielded realistic spectra for the 450 to 700 nm range; but bottom reflectance-based substrate classifications, generated using a random forest technique, were no more accurate than classifications derived from above-water field spectra. Additional hypothesis testing indicated that a combination of reflectance magnitude (brightness) and indices of spectral shape provided the most accurate riverbed classifications. Convolving field spectra to the response functions of a multispectral satellite and a hyperspectral imaging system did not reduce classification accuracies, implying that high spectral resolution was not essential. Supervised classifications of algal density produced from hyperspectral data and an inferred bottom reflectance image were not highly accurate, but unsupervised classification of the bottom reflectance image revealed distinct spectrally based clusters, suggesting that such an image could provide additional river information. We attribute the failure of bottom reflectance retrieval to yield more reliable substrate maps to a latent correlation between depth and bottom type. Accounting for the effects of depth might have eliminated a key distinction among substrates and thus reduced discriminatory power. Although further, more systematic study across a broader

  7. Amperometric biosensors based on carbon composite transducers

    Science.gov (United States)

    Lu, Fang

    1998-12-01

    Much current work in analytical chemistry is devoted to design of biosensors. One particular area in this field is the development of enzyme-based amperometric biosensors for the quantitative determination of a series of substrates in clinical, environmental, industrial and agricultural significance. This dissertation focuses on the design of improved amperometric biosensors based on carbon composite transducers. The use of metallized carbons as transducer materials results in remarkably selective amperometric biosensors. Such enzyme-based transducers eliminate major electroactive interferences, and hence circumvent the need for mediators or membrane barriers. The remarkable selectivity of metal-dispersed carbons is attributed to their strong, preferential, electrocatalytic capacity towards the reductive detection of biologically-generated hydrogen peroxide. Such electrocatalytic activity allows metal-dispersed biosensors to be operated at the optimal potential region between +0.1 and -0.2 V, where the unwanted reactions are neglected resulting in the lowest noise level. Several new materials (e.g., ruthenium on carbon, rhodium on carbon, etc.) and constructions (e.g., carbon fiber, electrochemical co-deposition transducer, etc.) were applied in the development of novel enzyme-based transducers in order to improve the selectivity and applicability of amperometric biosensors. The susceptibility of first-generation oxidase amperometric biosensing to oxygen fluctuations can be improved by using oxygen-rich fluorocarbons as the pasting binders in carbon paste enzyme transducers. Such binders provide an internal supply of oxygen resulting in efficient detection in oxygen-deficit conditions. In particular, the use of poly-chlorotrifluorethylene (Kel-F) oil as carbon paste binder results in a well-defined response and an identical signal up to 40 mM glucose in both the presence and absence of oxygen. Comparing with mediated or wired enzyme-based transducers, such internal

  8. Recent developments in polyurethane-based conducting polymer composites

    OpenAIRE

    Njuguna, James A. K.; Pielichowski, Krzysztof

    2004-01-01

    Polyurethane-based conducting composites with polyaniline, polythiophene or polypyrrole are in the class of modern macromolecular materials that combine the toughness and elasticity of polyurethane matrix with conductivity of intrinsically conducting polymers. Since the methods of preparation strongly influence the structure and properties of resulting composite/blend, this works aim at systematic description of polyurethane based conducting composites. This review has been ...

  9. Deoxyribonucleic acid base compositions of dermatophytes.

    Science.gov (United States)

    Davison, F D; Mackenzie, D W; Owen, R J

    1980-06-01

    DNA was extracted and purified from 55 dermatophyte isolates representing 34 species of Trichophyton, Microsporum and Epidermophyton. The base compositions of the chromosomal DNA were determined by CsCl density gradient centrifugation and were found to be in the narrow range of 48.7 to 50.3 mol % G + C. A satellite DNA component assumed to be of mitochondrial origin was present in most strains, with a G + C content ranging from 14.7 to 30.8 mol % G + C. Heterogeneity in microscopic and colonial characteristics was not reflected in differences in the mean G + C content of the chromosomal DNAs. Strains varied in the G + C contents of satelite DNA, but these did not correlate with traditional species concepts.

  10. Polyurea-Based Aerogel Monoliths and Composites

    Science.gov (United States)

    Lee, Je Kyun

    2012-01-01

    aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection for government and commercial applications. The rubbery polyureabased aerogel exhibits little dustiness, good flexibility and toughness, and durability typical of the parent polyurea polymer, yet with the low density and superior insulation properties associated with aerogels. The thermal conductivity values of polyurea-based aerogels at lower temperature under vacuum pressures are very low and better than that of silica aerogels. Flexible, rubbery polyurea-based aerogels are able to overcome the weak and brittle nature of conventional inorganic and organic aerogels, including polyisocyanurate aerogels, which are generally prepared with the one similar component to polyurethane rubber aerogels. Additionally, with higher content of hydrogen in their structures, the polyurea rubber-based aerogels will also provide inherently better radiation protection than those of inorganic and carbon aerogels. The aerogel materials also demonstrate good hydrophobicity due to their hydrocarbon molecular structure. There are several strategies to overcoming the drawbacks associated with the weakness and brittleness of silica aerogels. Development of the flexible fiber-reinforced silica aerogel composite blanket has proven to be one promising approach, providing a conveniently fielded form factor that is relatively robust in industrial environments compared to silica aerogel monoliths. However, the flexible, silica aerogel composites still have a brittle, dusty character that may be undesirable, or even intolerable, in certain application environments. Although the cross - linked organic aerogels, such as resorcinol- formaldehyde (RF), polyisocyanurate, and cellulose aerogels, show very high impact strength, they are also very brittle with little elongation (i.e., less rubbery). Also, silica and carbon aerogels are less efficient radiation shielding materials due

  11. Epoxy based photoresist/carbon nanoparticle composites

    DEFF Research Database (Denmark)

    Lillemose, Michael; Gammelgaard, Lauge; Richter, Jacob;

    2008-01-01

    We have fabricated composites of SU-8 polymer and three different types of carbon nanoparticles (NPs) using ultrasonic mixing. Structures of composite thin films have been patterned on a characterization chip with standard UV photolithography. Using a four-point bending probe, a well defined stress...... is applied to the composite thin film and we have demonstrated that the composites are piezoresistive. Stable gauge factors of 5-9 have been measured, but we have also observed piezoresistive responses with gauge factors as high as 50. As SU-8 is much softer than silicon and the gauge factor of the composite...

  12. Effect of cyclic loading on microleakage of silorane based composite compared with low shrinkage methacrylate-based composites

    Directory of Open Access Journals (Sweden)

    Hamid Kermanshah

    2016-01-01

    Conclusion: Silorane did not provide better marginal seal than the low shrinkage methacrylate-based composites (except Aelite. In addition, cyclic loading did not affect the marginal microleakage of evaluated composite restorations .

  13. Elastic Compositions Based on Polyurethane/ Aliphatic Polyesters

    International Nuclear Information System (INIS)

    Aliphatic polyesters were prepared by melt condensation reaction of a dicarboxylic acid such as adipic and sebacic with different types of diol compounds in 1: 1.1 molar ratio. Ethylene glycol, di-, trio, tetra ethylene glycol and poly( ethylene glycol) with different molecular weights 1000, 4000, 6000 as well as the prepared hydroxy natural rubber were used as diol compounds. Polyurethane, with NCO/OH ratio equal 4, was synthesized from the reaction of toluene diisocyanate with poly(ethylene glycol) 1 000. The prepared polyurethane was mixed with different weight percentages of the prepared aliphatic polyesters. The film samples were tested mechanically, electrically and chemically. The results show that the weight percentage 10% of the added polyadipate or poly sebacate glycols improves flexibility, electrical volume resistivity, dielectric constant and dielectric loss of unmodified rigid polyurethane film sample as well as reduces its swelling by aromatic solvents. All the above mentioned properties improve by increasing the hydrocarbon chain length of the glycol portion in the glycol used and the number of methylene in the aliphatic dicarboxylic acid. Compositions based on hydroxy natural rubber impart better properties than those based on ethylene glycols

  14. Asphaltenes-based polymer nano-composites

    Science.gov (United States)

    Bowen, III, Daniel E

    2013-12-17

    Inventive composite materials are provided. The composite is preferably a nano-composite, and comprises an asphaltene, or a mixture of asphaltenes, blended with a polymer. The polymer can be any polymer in need of altered properties, including those selected from the group consisting of epoxies, acrylics, urethanes, silicones, cyanoacrylates, vulcanized rubber, phenol-formaldehyde, melamine-formaldehyde, urea-formaldehyde, imides, esters, cyanate esters, allyl resins.

  15. Composite Based EHV AC Overhead Transmission Lines

    DEFF Research Database (Denmark)

    Sørensen, Thomas Kjærsgaard

    and analysed with regard to the possibilities, limitations and risks widespread application of composite materials on EHV AC overhead transmission lines may present. To form the basis for evaluation of the useability of composite materials, dierent overhead line projects aimed at reducing the environmental...

  16. Flexible hydrogel-based functional composite materials

    Science.gov (United States)

    Song, Jie; Saiz, Eduardo; Bertozzi, Carolyn R; Tomasia, Antoni P

    2013-10-08

    A composite having a flexible hydrogel polymer formed by mixing an organic phase with an inorganic composition, the organic phase selected from the group consisting of a hydrogel monomer, a crosslinker, a radical initiator, and/or a solvent. A polymerization mixture is formed and polymerized into a desired shape and size.

  17. A magnetoelectric composite based microwave phase shifter

    Science.gov (United States)

    Bichurin, M. I.; Petrov, V. M.; Srinivasan, G.

    2008-03-01

    Magnetoelectric (ME) properties of ferrite-ferroelectric composites arise from their response to elastic and electromagnetic force fields. The unique combination of magnetic, electrical, and ME interactions opens up the possibility of electric field tunable ferromagnetic resonance (FMR) based devices [1]. Here we discuss an ME phase shifter operating in the FMR region at 9.3 GHz. A slot line on a yttrium iron garnet film bonded to lead zirconate titanate (PZT) provides a basis for the phase shifter. The circularly polarized microwave magnetic field of the slot line interacts with the ferrite and causes variation of phase velocity with the controlling magnetic and electric fields. Electrical tuning is realized with the application of a control voltage due to PZT. The estimated phase shift per unit length and unit voltage is to 20 deg/cm kV for a PZT thickness of 0.5 mm. 1 S. Shastry and G. Srinivasan, M.I. Bichurin, V.M. Petrov, A.S. Tatarenko. Phys. Rev. B, 70 064416 (2004). - supported by grants from the Office of Naval Research and the Russian Foundation for Basic Research.

  18. CARBON-CONTAINING COMPOSITES BASED ON METALS

    Directory of Open Access Journals (Sweden)

    VAGANOV V. E.

    2015-10-01

    Full Text Available Problem statement Among the developed technologies metal-composites production,a special place takes powder metallurgy, having fundamental differences from conventionally used foundry technologies. The main advantages of this technology are: the possibility of sensitive control, the structure and phase composition of the starting components, and ultimately the possibility of obtaining of bulk material in nanostructured state with a minimum of processing steps. The potential reinforcers metals include micro and nano-sized oxides, carbides, nitrides, whiskers. The special position is occupied with carbon nanostructures (CNS: С60 fullerenes, single-layer and multi-layer nanotubes, onions (spherical "bulbs", nano-diamonds and graphite,their properties are being intensively studied in recent years. These objects have a high thermal and electrical conductivity values, superelasticity, and have a strength approximate to the theoretical value, which can provide an obtaining composite nanomaterial with a unique set of physical and mechanical properties. In creation of a metal matrix composite nanomaterials (CM, reinforced by various CNS, a special attention should be given to mechanical activation processes (MA already at the stage of preparation of the starting components affecting the structure, phase composition and properties of aluminum-matrix composites. Purpose. To investigate the influence of mechanical activation on the structure and phase composition of aluminum-matrix composites. Conclusion. The results of the study of the structure and phase composition of the initial and mechanically activated powders and bulk-modified metal-composites are shown, depending on the type and concentration of modifying varieties CNS, regimes of MA and parameters of compaction. The study is conducted of tribological properties of Al-CNS OF nanostructured materials.

  19. A magnetoelectric composite based signal generator

    Science.gov (United States)

    Fetisov, Y. K.; Serov, V. N.; Fetisov, L. Y.; Makovkin, S. A.; Viehland, D.; Srinivasan, G.

    2016-05-01

    Self-oscillations in an active loop consisting of a wide-band amplifier and a magnetoelectric composite in the feedback circuit have been observed. The composite with a ferroelectric lead zirconate titanate bimorph and ferromagnetic Metglas serves as a resonator that determines the frequency of oscillations and provides the feedback voltage. Under amplitude balance and phase matching conditions, the device generated signals at 2.3 kHz, at the bending resonance frequency of the composite. The oscillations were observed over a specific range of magnetic bias H. The shape of the signal generated is dependent on electrical circuit parameters and magnitude and orientation of H.

  20. Effect of base bitumen composition on asphalt rubber binder properties

    OpenAIRE

    Partl, M.N.; Ould-Henia, M.; Dumont, A.-G.

    2008-01-01

    The asphalt rubber blend properties are strongly related to its base components properties. The base bitumen composition is considered as a key factor influencing the final rheological properties of asphalt rubber binder. This paper describes results from a laboratory investigation of the interaction between crumb rubber and different composition bitumen according to the wet process. The bitumen composition is determined according to the SARA decomposition approac...

  1. Polymer composite material structures comprising carbon based conductive loads

    OpenAIRE

    Jérôme, Robert; Pagnoulle, Christophe; Detrembleur, Christophe; Thomassin, Jean-Michel; Huynen, Isabelle; Bailly, Christian; Bednarz, Luikasz; Daussin, Raphaël; Saib, Aimad; Baudouin, Anne-Christine; Laloyaux, Xavier

    2007-01-01

    The present invention provides a polymer composite material structure comprising at least one layer of a foamed polymer composite material comprising a foamed polymer matrix and 0.1 wt % to 6 wt % carbon based conductive loads, such as e.g. carbon nanotubes, dispersed in the foamed polymer matrix. The polymer composite material structure according to embodiments of the present invention shows good shielding and absorbing properties notwithstanding the low amount of carbon based conductive loa...

  2. Polymer composite material structures comprising carbon based conductive loads

    OpenAIRE

    Jérôme, Robert; Pagnoulle, Christophe; Detrembleur, Christophe; Thomassin, Jean-Michel; Huynen, Isabelle; Bailly, Christian; Bednarz, Lucasz; Daussin, Raphaël; Saib, Aimad

    2006-01-01

    The present invention provides a polymer composite material structure comprising at least one layer of a foamed polymer composite material comprising a foamed polymer matrix and 0.1 to 6 wt% carbon based conductive loads, such as e.g. carbon nanotubes, dispersed in the foamed polymer matrix. The polymer composite material structure according to embodiments of the present invention shows good shielding and absorbing properties notwithstanding the low amount of carbon based conductive loads. Th...

  3. A channel-based coordination model for component composition

    NARCIS (Netherlands)

    Arbab, F.

    2002-01-01

    In this paper, we present $P epsilon omega$, a paradigm for composition of software components based on the notion of mobile channels. $P repsilon omega$ is a channel-based exogenous coordination model wherein complex coordinators, called {em connectors are compositionally built out of simpler ones.

  4. Reo: A Channel-based Coordination Model for Component Composition

    NARCIS (Netherlands)

    Arbab, F.

    2004-01-01

    In this paper, we present Reo, which forms a paradigm for composition of software components based on the notion of mobile channels. Reo is a channel-based exogenous coordination model in which complex coordinators, called connectors, are compositionally built out of simpler ones. The simplest conne

  5. Composites in a Dexter-Based Hypermedia Framwork

    DEFF Research Database (Denmark)

    Grønbæk, Kaj

    1994-01-01

    This paper discusses the design and use of a generic composite mechanism in the object oriented DEVISE Hypermedia (DHM) development framework. The DHM development framework is based on the Dexter Hypertext Reference Model, which introduces a notion of composite to model editors with complex or...... multiple types of contents. The original Dexter notion of composites is, however, insufficient to cover structural composites including or referencing other components. Thus the DHM framework has been extended with generic composite classes suited to support structures within the hypermedia network itself...

  6. Polyurethane Based Inhibition for High Flame Temperature Nitramine Based Composite Modified Double Base propellant

    OpenAIRE

    S. D. Kakade; M. V. Vaidya; D. G. Khangaonkar; P. K. Divekar; U. B. Kadam; S. N. Asthana

    1998-01-01

    The findings for polypropylene glycol (PPG) and hydroxyl-terminated polybutadiene (HTPB)-based inhibition systems are reported. These findings established that the inhibition system comprising HTPB-IPDI-IDP binder and Sb/sub 2/O/sub 3/-C black filler is most suitable for advanced nitramine-based composite modified double-base propellants in terms of mechanical properties and processibility. The promising composition was characterised for glass-transition behaviour and propellant-inhibi...

  7. Posterior resin-based composite: review of the literature.

    Science.gov (United States)

    Burgess, J O; Walker, Richard; Davidson, J M

    2002-01-01

    The use of direct posterior resin-based composite has increased primarily due to patient esthetic desires and product improvements. Other factors (substantiated or not) contributing to increased use of resin-based composite are environmental and health concerns with dental amalgam. New visible light cured resin-based composite products are introduced yearly, as manufacturers continue to improve this tooth-colored restorative material. This paper will characterize current posterior resin-based composite materials (hybrid, microfill, flowable, and packable), review recent in vitro and clinical research, and recommend indications for these materials. In addition, the literature on compomers will be reviewed and recommendation made for their use. The data indicates that composite resin is a technique sensitive restorative material that can be used in large preparations if proper manipulation and isolation can be maintained. Compomers may also be used as an esthetic posterior restorative if proper isolation is provided.

  8. Recent developments in composite-based optics

    Science.gov (United States)

    Kasl, Eldon P.; Mehle, Gregory V.; Dyer, Jack E.; Clark, Harold R.; Connell, Steven J.; Sheikh, David A.

    1998-08-01

    The objective of this paper is to report the recent developments in lightweight mirror technology that have occurred at Composite Optics, Inc. The developments occurred as a result of the activities being conducted in support the Next Generation Space Telescope, microwave limb sounder, and small business innovative research programs. Our sponsors on these programs are the Marshall and Goddard Space Flight Centers and the JPL. The requirements, design approach, actual performance, and the technology status for each program are summarized in the following sections. The emergence of composite designs provides exciting potential for nontraditional, accurate, lightweight, stable, stiff, and high strength composite mirrors. This evolving technology promises significant improvement in reducing weight, cost and cycle time for future IR, visible, and ex- ray systems. Customers currently embracing composite mirror technology for radiometric use are already reaping substantial system performance benefits. Other customers interested in LIDAR, IR, visible, and grazing incidence x- ray applications are eagerly awaiting successful completion of current technology development and demonstration efforts.

  9. Development of Polymethylmethacrylate Based Composite for Gas Sensing Application

    OpenAIRE

    Devikala, S.; P. Kamaraj

    2011-01-01

    Gas detection instruments are increasingly needed for industrial health and safety, environmental monitoring and process control. Conductive polymer composites have various industrial applications. The composite prepared by mixing carbon black with polymethylmethacrylate (PMMA) has very good gas sensing applications. The gas sensors based on carbon nanotube/polymer, ceramic and metal oxide composites such as epoxy, polyimide, PMMA / Barium titanate and tin oxide have also been developed. In t...

  10. Fracture Behavior of Alumina-based Prismatic Ceramic Composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The fracture toughness and fracture work of Al2O3/SiC prismatic ceramic composites was evaluated in this paper, which showed the fracture energy was improved greatly. Based on the observation for crack propagation and fracture morphology, the fracture behavior of the prismatic composites was analyzed. In the bending test, the composites displayed a non-catastrophic behavior and a graceful failure with reasonable load-carrying capability.

  11. Cytotoxicity evaluation of methacrylate- and silorane-based composite resins

    Directory of Open Access Journals (Sweden)

    Gulsah Goktolga Akin

    2012-10-01

    Full Text Available

    Objectives: The objective of this study was to investigate and compare the cytotoxic effects of four composite resin materials with different content.

    Material and Methods: Two traditional methacrylate-based (Clearfil AP-X, RefleXions, as well as a self-adhering methacrylate-based (Vertise Flow and a silorane-based (Filtek Silorane composite resin were tested in the experiment. Ten cylindrical specimens were made of each material, using a mould (2mm. thick and 8 mm. in diameter. An agar diffusion method was employed, and cytotoxicity rankings were determined using lysis index scores. For statistical analysis, Kruskal-Wallis and Mann-Whitney U-tests were used.

    Results: Amongst the composite resins, the silorane-based composite was found to be less cytotoxic than the methacrylate-based composite resins, which all had the same cytotoxicity ranking.

    Conclusions: The silorane-based composite resin was considered more biocompatible than the methacrylate-based composite resins.

  12. Un Cours de composition francaise par ordinateur (A Computer-Based Course in French Composition).

    Science.gov (United States)

    Landes, Anne; Kaplan, Alice

    1988-01-01

    The origins, organization, and methods of a Columbia University course offering computer-based instruction in French composition are outlined, and the progress of four individual students is described. (MSE)

  13. Detection of Atmospheric Composition Based on Lidar

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jinye; Tong Yala; Yang Xiaoling; Gong Jiaoli [School of science, Hubei University of Technology, Wuhan 430068 (China); Gong Wei, E-mail: yezi.zh@163.com [State Key Laboratory for Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan 430079 (China)

    2011-02-01

    A summary overview about the types of lidar and their own applications on atmosphere detection is presented. Measurement of atmospheric aerosols by Mie lidar and Raman lidar is focused. The vertical profiles of aerosols in the atmosphere are retrieved. And at the same time, through analyzing aerosol vertical content distribution, the atmosphere boundary layer and the cloud are also observed. All the results show that the lidar has good performance on detecting the atmospheric composition.

  14. STRAW BASED PARTICLEBOARD BONDED WITH COMPOSITE ADHESIVES

    Directory of Open Access Journals (Sweden)

    Mingwei Di

    2011-02-01

    Full Text Available Environmentally friendly particleboard was prepared with wheat straw, an inexpensive material. The particleboard was produced by a mixing process, using a composite adhesive comprised of urea-formaldehyde (UF adhesives and EPU. The performance of the board was evaluated by measuring internal bonding strength (IB, thickness swelling, modulus of rupture (MOR, modulus of elasticity (MOE, and formaldehyde emission. The experimental results showed that maximum of dry and wet internal bonding strength, modulus of rupture, modulus of elasticity were 0.45MPa, 0.18MPa, 31.80MPa, and 5043MPa, respectively. The thickness swelling (TS2h and thickness swelling (TS24h were 3.9% and 10.7%, respectively. The composite adhesives and particleboards were measured by differential scanning calorimentry (DSC, dynamic mechanical analyzer (DMA, X-ray photoelectron spectroscopy (XPS and scanning electron microscope (SEM measurements. The results indicated that the composite adhesive of UF/EPU could contribute to excellent mechanical, thermal, and water-resistant properties of the wheat straw particleboards.

  15. Theory for a gas composition sensor based on acoustic properties.

    Science.gov (United States)

    Phillips, Scott; Dain, Yefim; Lueptow, Richard M

    2003-01-01

    Sound travelling through a gas propagates at different speeds and its intensity attenuates to different degrees depending upon the composition of the gas. Theoretically, a real-time gaseous composition sensor could be based on measuring the sound speed and the acoustic attenuation. To this end, the speed of sound was modelled using standard relations, and the acoustic attenuation was modelled using the theory for vibrational relaxation of gas molecules. The concept for a gas composition sensor is demonstrated theoretically for nitrogen-methane-water and hydrogen-oxygen-water mixtures. For a three-component gas mixture, the measured sound speed and acoustic attenuation each define separate lines in the composition plane of two of the gases. The intersection of the two lines defines the gas composition. It should also be possible to use the concept for mixtures of more than three components, if the nature of the gas composition is known to some extent. PMID:14552356

  16. Shape memory-based tunable resistivity of polymer composites

    Science.gov (United States)

    Luo, Hongsheng; Zhou, Xingdong; Ma, Yuanyuan; Yi, Guobin; Cheng, Xiaoling; Zhu, Yong; Zu, Xihong; Zhang, Nanjun; Huang, Binghao; Yu, Lifang

    2016-02-01

    A conductive composite in bi-layer structure was fabricated by embedding hybrid nanofillers, namely carbon nanotubes (CNTs) and silver nanoparticles (AgNPs), into a shape memory polyurethane (SMPU). The CNT/AgNP-SMPU composites exhibited a novel tunable conductivity which could be facially tailored in wide range via the compositions or a specifically designed thermo-mechanical shape memory programming. The morphologies of the conductive fillers and the composites were investigated by scanning electron microscope (SEM). The mechanical and thermal measurements were performed by tensile tests and differential scanning calorimetry (DSC). By virtue of a specifically explored shape memory programming, the composites were stretched and fixed into different temporary states. The electrical resistivity (Rs) varied accordingly, which was able to be stabilized along with the shape fixing. Theoretical prediction based upon the tunneling model was performed. The Rs-strain curves of the composites with different compositions were well fitted. Furthermore, the relative resistivity and the Gauge factor along with the elongation were calculated. The influence of the compositions on the strain-dependent Rs was disclosed. The findings provided a new avenue to tailor the conductivity of the polymeric nano-composites by combining the composition method and a thermo-mechanical programming, which may greatly benefit the application of intelligent polymers in flexible electronics and sensors fields.

  17. Study on the Electrospun CNTs/Polyacrylonitrile-Based Nanofiber Composites

    OpenAIRE

    Bo Qiao; Xuejia Ding; Xiaoxiao Hou; Sizhu Wu

    2011-01-01

    CNTs/PAN nanofibers were electrospun from PAN-based solution for the preparation of carbon nanofiber composites. The as-spun polyacrylonitrile-based nanofibers were hot-stretched by weighing metal in a temperature controlled oven. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the morphology of the nanofibers, which indicated that carbon nanotubes were dispersed well in the composites and were completely wrapped by PAN matrix. Because o...

  18. Eco-Challenges of Bio-Based Polymer Composites

    Directory of Open Access Journals (Sweden)

    Anita Grozdanov

    2009-08-01

    Full Text Available In recent years bio-based polymer composites have been the subject of many scientific and research projects, as well as many commercial programs. Growing global environmental and social concern, the high rate of depletion of petroleum resources and new environmental regulations have forced the search for new composites and green materials, compatible with the environment. The aim of this article is to present a brief review of the most suitable and commonly used biodegradable polymer matrices and NF reinforcements in eco-composites and nanocomposites, with special focus on PLA based materials.

  19. Physical and mechanical properties of composite materials of different compositions based on waste products

    Directory of Open Access Journals (Sweden)

    A.E. Burdonov

    2012-12-01

    Full Text Available This paper presents a study on the effect of mineral filler on the polymer composite material based on waste products of heat and power engineering - fly ash. This type of waste products has never been used for the production of polymer-mineral composites. Depending on the type of ash, its chemical composition and its quantity in the material, we can adjust the properties of the resulting composites. The use of fly ash as a filler will not only make a product less expensive, but it also will reduce development pressure on the environment and improve the physical and mechanical properties of the material. The article shows research results of the ash chemical composition as well as the properties of the resulting materials on its basis. According to the research conclusions there is a prospect for using this material in the construction industry.

  20. Polyurethane Based Inhibition for High Flame Temperature Nitramine Based Composite Modified Double Base propellant

    Directory of Open Access Journals (Sweden)

    S. D. Kakade

    1998-10-01

    Full Text Available The findings for polypropylene glycol (PPG and hydroxyl-terminated polybutadiene (HTPB-based inhibition systems are reported. These findings established that the inhibition system comprising HTPB-IPDI-IDP binder and Sb/sub 2/O/sub 3/-C black filler is most suitable for advanced nitramine-based composite modified double-base propellants in terms of mechanical properties and processibility. The promising composition was characterised for glass-transition behaviour and propellant-inhibition bond strength. Propellant grains inhibited with selected formulations were subjected to static evaluation at extreme temperatures and limited aging studies to obtain data of practical value.

  1. Nitramine-Based High Energy Propellant Compositions for Tank Guns

    Directory of Open Access Journals (Sweden)

    R.S. Damse

    2000-01-01

    Full Text Available Six different RDX-based gun propellant compositions have been formulated and studied to select the most suitable composition for tank gun ammunition in terms of higher force constant at relatively lower flame temperature (T. Ballistic'performance of the compositions was evaluated on the basis of closed vessel test. JIea(energy was determined using a bomb calorimeter. Sensitivity, thermal characteristics, stability and mechanical properties of the compositions were studied for assessing their suitabilitY for application. The composition containing 65 per cent RDX and 28 per cent nitrocellulose was found to provide higher level of force constant at relatively lower T f ' reasonably good burning rate characteristics and mechanical properties.

  2. Aluminum-Based Cast In Situ Composites: A Review

    Science.gov (United States)

    Pramod, S. L.; Bakshi, Srinivasa R.; Murty, B. S.

    2015-06-01

    In situ composites are a class of composite materials in which the reinforcement is formed within the matrix by reaction during the processing. In situ method of composite synthesis has been widely followed by researchers because of several advantages over conventional stir casting such as fine particle size, clean interface, and good wettability of the reinforcement with the matrix and homogeneous distribution of the reinforcement compared to other processes. Besides this, in situ processing of composites by casting route is also economical and amenable for large scale production as compared to other methods such as powder metallurgy and spray forming. Commonly used reinforcements for Al and its alloys which can be produced in situ are Al2O3, AlN, TiB2, TiC, ZrB2, and Mg2Si. The aim of this paper is to review the current research and development in aluminum-based in situ composites by casting route.

  3. Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites

    Directory of Open Access Journals (Sweden)

    Drago Skrtic

    2009-11-01

    Full Text Available Our studies of amorphous calcium phosphate (ACP-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/remineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-α-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and

  4. Processing and characterization of bio-based composites

    Science.gov (United States)

    Lu, Hong

    Much research has focused on bio-based composites as a potential material to replace petroleum-based plastics. Considering the high price of Polyhydroxyalkanoates (PHAs), PHA/ Distiller's Dried Grains with Solubles (DDGS) composite is a promising economical and high-performance biodegradable material. In this paper, we discuss the effect of DDGS on PHA composites in balancing cost with material performance. Poly (lactic acid) PLA/DDGS composite is another excellent biodegradable composite, although as a bio-based polymer its degradation time is relatively long. The goal of this research is therefore to accelerate the degradation process for this material. Both bio-based composites were extruded through a twin-screw microcompounder, and the two materials were uniformly mixed. The morphology of the samples was examined using a Scanning Electron Microscope (SEM); thermal stability was determined with a Thermal Gravimetric Analyzer (TGA); other thermal properties were studied using Differential Scanning Calorimetry (DSC) and a Dynamic Mechanical Analyzer (DMA). Viscoelastic properties were also evaluated using a Rheometer.

  5. Microstructure and properties of pitch-based carbon composites

    Science.gov (United States)

    Blanco; Santamaria; Bermejo; Bonhomme; Menendez

    1999-11-01

    Pitches prepared in the laboratory by thermal treatment and air-blowing of a commercial coal-tar pitch were used as matrix precursors of carbon composites using granular petroleum coke, foundry coke, amorphous graphite and anthracite. Pitches were characterized by standard procedures (elemental analysis, softening point, solubility tests and carbon yield) and light microscopy (mesophase content). Pitch pyrolysis behaviour was monitored by thermogravimetric analysis and from the optical texture of cokes. Pitch wettability to the different carbons, at different temperatures, was also studied. Experimental conditions selected for the preparation of composites were based on pitch composition and properties. The main microstructural features of composites were determined by light microscopy and scanning electron microscopy. Composite properties were described in terms of their density, porosity and compressive strength, and related to composite microstructure and the characteristics of the precursors. Thermal treatment and air-blowing of pitch improved carbon composite structure and properties. The lowest porosities and best mechanical properties were observed in those composites obtained with the thermally treated pitches combined with foundry coke and anthracite.

  6. Some functional properties of composite material based on scrap tires

    Science.gov (United States)

    Plesuma, Renate; Malers, Laimonis

    2013-09-01

    The utilization of scrap tires still obtains a remarkable importance from the aspect of unloading the environment from non-degradable waste [1]. One of the most prospective ways for scrap tires reuse is a production of composite materials [2] This research must be considered as a continuation of previous investigations [3, 4]. It is devoted to the clarification of some functional properties, which are considered important for the view of practical applications, of the composite material. Some functional properties of the material were investigated, for instance, the compressive stress at different extent of deformation of sample (till 67% of initial thickness) (LVS EN 826) [5] and the resistance to UV radiation (modified method based on LVS EN 14836) [6]. Experiments were realized on the purposefully selected samples. The results were evaluated in the correlation with potential changes of Shore C hardness (Shore scale, ISO 7619-1, ISO 868) [7, 8]. The results showed noticeable resistance of the composite material against the mechanical influence and ultraviolet (UV) radiation. The correlation with the composition of the material, activity of binder, definite technological parameters, and the conditions supported during the production, were determined. It was estimated that selected properties and characteristics of the material are strongly dependent from the composition and technological parameters used in production of the composite material, and from the size of rubber crumb. Obtained results show possibility to attain desirable changes in the composite material properties by changing both the composition and technological parameters of examined material.

  7. QoS Based Dynamic Web Services Composition & Execution

    CERN Document Server

    Khan, Farhan Hassan; Javed, M Younus; Khan, Aihab; Khiyal, Malik Sikandar Hayat

    2010-01-01

    The use of web services has dominated software industry. Existing technologies of web services are extended to give value added customized services to customers through composition. Automated web service composition is a very challenging task. This paper proposed the solution of existing problems and proposed a technique by combination of interface based and functionality based rules. The proposed framework also solves the issues related to unavailability of updated information and inaccessibility of web services from repository/databases due to any fault/failure. It provides updated information problem by adding aging factor in repository/WSDB (Web Services Database) and inaccessibility is solved by replication of WSDB. We discussed data distribution techniques and proposed our framework by using one of these strategies by considering quality of service issues. Finally, our algorithm eliminates the dynamic service composition and execution issues, supports web service composition considering QoS (Quality of ...

  8. Resin-based composite as a direct esthetic restorative material.

    Science.gov (United States)

    Malhotra, Neeraj; Mala, Kundabala; Acharya, Shashirashmi

    2011-06-01

    The search for an ideal esthetic material for tooth restoration has resulted in significant improvements in both materials and the techniques for using them. Various resin-based composite (RBC) materials have recently been introduced into the market that offer improved esthetic and physical properties. This article reviews RBCs, including their compositions, advantages, and disadvantages, that are contemporary to today's clinical practice as well as those that are under research consideration and/ or in clinical trial phase.

  9. THE λ-GR(O)BNER BASES UNDER POLYNOMIAL COMPOSITION

    Institute of Scientific and Technical Information of China (English)

    Jinwang LIU; Dongmei LI; Xiaosong CHEN

    2007-01-01

    Polynomial composition is the operation of replacing variables in a polynomial with other polynomials. λ-Gr(o)bner basis is an especial Gr(o)bner basis. The main problem in the paper is: when does composition commute with λ-Gr(o)bner basis computation? We shall answer better the above question. This has a natural application in the computation of λ-Gr(o)bner bases.

  10. Properties of recycled polypropylene based composites incorporating treated hardwood sawdust

    Science.gov (United States)

    Shulga, Galia; Jaunslavietis, Jevgenijs; Ozolins, Jurijs; Neiberte, Brigita; Verovkins, Anrijs; Vitolina, Sanita; Shakels, Vadims

    2016-05-01

    The effect of different treatment of hardwood sawdust under mild conditions on contact angles, adhesion energy and water sorption was studied. A comparison of these indices for the hardwood treated sawdust and the composites filled with them was performed. The treatment promoted the compatibility between the recycled polypropylene and the hardwood filler. The inclusion of the lignin-based compatibiliser in the composite, containing the ammoxidised wood filler, essentially improved its mechanical properties.

  11. RESEARCH ON REUSE-BASED WEB SERVICES COMPOSITION

    Institute of Scientific and Technical Information of China (English)

    Rao Yuan; Li Zunchao; Feng Boqin

    2005-01-01

    Objective To solve the three principal problems for reusing the software components, i.e., existence, discovery and availability principles, web services provided a new solution for reusing and assembling web software or components under distributed environment with a series of XML-based protocols. Methods A 4+1 meta-model between atomic services, such as Sequence, Parallelism, Alternation, Substitute and Iteration, and a kind of service composition description language in composition process are investigated. Furthermore, an architecture-based service composition model with Ontology Engine is proposed, which is based on the software architecture life-cycle model and provides a mechanism for services composition with dynamic management and deployment. Results The results of the prototype system development show that the service-composed application not only reused the web service components, but also reused the data resources located in distributed databases. Conclusion The method of reused-based web services composition observably decreases the period and cost of development and greatly improves the programming efficiency.

  12. Compressive elastic modulus of natural fiber based binary composites

    Science.gov (United States)

    Widayani, Susanah, Y.; Utami, L. S.; Khotimah, S. N.; Viridi, S.

    2012-06-01

    The composites made of bamboo apus fiber - epoxy resin and charcoal - tapioca starch with several compositions have been synthesized. Bamboo fiber powder as the rest of cutting process was refined and filtered by mesh 40 before used. Epoxy resin 1021A and hardener 1021B has been used as resin. The synthesis of epoxy resin-based composites was carried out via simple mixing method by adding adequate 70% ethanol solution before drying. The 100 mesh-filtered dry charcoal was mixed with tapioca mixture before it was pressed and dried to produce briquette composites. To study the compressive elastic modulus of the composites, pressure tests using Mark 10 Pressure Test Machine have been carried out. It was found that all the composites show maximum compressive elastic modulus at certain component compositions. The maximum elastic modulus for bamboo fiber-epoxy resin, charcoal - epoxy resin and charcoal-tapioca starch were observed at 52.9%, 56.3%, and 25.0% of mass fraction of bamboo fiber, charcoal and tapioca starch, respectively.

  13. Properties of lightweight cement-based composites containing waste polypropylene

    Science.gov (United States)

    Záleská, Martina; Pavlíková, Milena; Pavlík, Zbyšek

    2016-07-01

    Improvement of buildings thermal stability represents an increasingly important trend of the construction industry. This work aims to study the possible use of two types of waste polypropylene (PP) for the development of lightweight cement-based composites with enhanced thermal insulation function. Crushed PP waste originating from the PP tubes production is used for the partial replacement of silica sand by 10, 20, 30, 40 and 50 mass%, whereas a reference mixture without plastic waste is studied as well. First, basic physical and thermal properties of granular PP random copolymer (PPR) and glass fiber reinforced PP (PPGF) aggregate are studied. For the developed composite mixtures, basic physical, mechanical, heat transport and storage properties are accessed. The obtained results show that the composites with incorporated PP aggregate exhibit an improved thermal insulation properties and acceptable mechanical resistivity. This new composite materials with enhanced thermal insulation function are found to be promising materials for buildings subsoil or floor structures.

  14. Photo-excited terahertz switch based on composite metamaterial structure

    Science.gov (United States)

    Wang, Guocui; Zhang, Jianna; Zhang, Bo; He, Ting; He, Yanan; Shen, Jingling

    2016-09-01

    A photo-excited terahertz switch based on a composite metamaterial structure was designed by integration of photoconductive silicon into the gaps of split-ring resonators. The conductivity of the silicon that was used to fill the gaps in the split-ring resonators was tuned dynamically as a function of the incident pump power using laser excitation, leading to a change in the composite metamaterial structure's properties. We studied the transmission characteristics of the composite metamaterial structure for various silicon conductivities, and the results indicated that this type of composite metamaterial structure could be used as a resonance frequency tunable terahertz metamaterial switch. We also designed other structures by filling different gaps with silicon, and proved that these structures could be used as terahertz metamaterial switches can change the working mode from a single frequency to multiple frequencies.

  15. Microscopic structure and properties of wood-based foaming composites

    Institute of Scientific and Technical Information of China (English)

    Zheng WANG; Li GAO; Guilan ZHANG; Liang CHANG

    2008-01-01

    In order to reduce the density of wood-based composites without causing a deterioration of their mech-anical properties, we studied the process of manufacturing wood-based composites. A combination of polymer foaming technology and flat hot-pressing technology was used. The microscopic structure of the various wood-based composites was analyzed with a scanning electron microscope (SEM). Modulus of rupture (MOR), modulus of elasticity (MOE), impact strength, and thickness expansion rate of water sorption (TS) were all measured. The results showed that fibers loosely inter-weave, and fibers had been connected by micropore. They also showed that spaces between fibers had big micropore structure. MOR, MOE and impact strength were the high-est among three levels of ratio. When the total content of resin and foaming agent were 20% by weight, TS was higher. A hot-pressing temperature of 120℃ was optimal. At the low temperatures of 80℃, the foaming process was uncompleted. At a higher temperature, micropores burst at a certain pressure. Based on the variance analysis and maximum difference analysis, a significance test shows that the optimum conditions for the total content of resin and foaming agent is 20% by weight, with a hot pressing temperature of 120℃ for 15 min. Under these conditions, the properties of wood-based foaming composites all achieved the industry standard.

  16. Oxidation resistance coating for niobium base structural composites

    International Nuclear Information System (INIS)

    Oxidation behavior of Al-rich Mo(Si,Al)2 base alloys, which is a candidate material for the oxidation resistance coating on Nb base structural composites, were investigated by thermogravimetry. The Mo(Si,Al)2 base alloys containing Mo5(Si,Al)3 up to about 10 vol% exhibits excellent oxidation resistance at temperatures ranging from 780 to 1580 K, particularly at 1580 K due to continuous Al2O3 layer development. To evaluate the applicability of the Mo(Si,Al)2 base coating, plasma spraying on Nb base composites were undertaken. However, interface reaction layer was found to form during the following heat treatment. Preparation of Mo(Si,Al)2/Al2O3/Nb layered structures via powder metallurgical process was attempted to preclude diffusion reaction between coating and substrate. (orig.)

  17. Study on the Electrospun CNTs/Polyacrylonitrile-Based Nanofiber Composites

    Directory of Open Access Journals (Sweden)

    Bo Qiao

    2011-01-01

    Full Text Available CNTs/PAN nanofibers were electrospun from PAN-based solution for the preparation of carbon nanofiber composites. The as-spun polyacrylonitrile-based nanofibers were hot-stretched by weighing metal in a temperature controlled oven. Scanning electron microscopy (SEM and transmission electron microscopy (TEM were used to characterize the morphology of the nanofibers, which indicated that carbon nanotubes were dispersed well in the composites and were completely wrapped by PAN matrix. Because of the strong interfacial interaction between CNTs and PAN, the CNTs/PAN application performance will be enhanced correspondingly, such as the mechanical properties and the electrical conductivity. It was concluded that the hot-stretched CNTs/PAN nanofibers can be used as a potential precursor to produce high-performance carbon composites.

  18. Reliability Based Optimization of Composite Laminates for Frequency Constraint

    Institute of Scientific and Technical Information of China (English)

    Wu Hao; Yan Ying; Liu Yujia

    2008-01-01

    The reliability based optimization (RBO) issue of composite laminates under fundamental frequency constraint is studied. Considering the uncertainties of material properties, the frequency constraint reliability of the structure is evaluated by the combination of response surface method (RSM) and finite element method. An optimization algorithm is developed based on the mechanism of laminate frequency characteristics, to optimize the laminate in terms of the ply amount and orientation angles. Numerical examples of composite laminates and cylindrical shell illustrate the advantages of the present optimization algorithm on the efficiency and applicability respects.The optimal solutions of RBO are obviously different from the deterministic optimization results, and the necessity of considering material property uncertainties in the composite srtuctural frequency constraint optimization is revealed.

  19. Additives for cement compositions based on modified peat

    Science.gov (United States)

    Kopanitsa, Natalya; Sarkisov, Yurij; Gorshkova, Aleksandra; Demyanenko, Olga

    2016-01-01

    High quality competitive dry building mixes require modifying additives for various purposes to be included in their composition. There is insufficient amount of quality additives having stable properties for controlling the properties of cement compositions produced in Russia. Using of foreign modifying additives leads to significant increasing of the final cost of the product. The cost of imported modifiers in the composition of the dry building mixes can be up to 90% of the material cost, depending on the composition complexity. Thus, the problem of import substitution becomes relevant, especially in recent years, due to difficult economic situation. The article discusses the possibility of using local raw materials as a basis for obtaining dry building mixtures components. The properties of organo-mineral additives for cement compositions based on thermally modified peat raw materials are studied. Studies of the structure and composition of the additives are carried out by physicochemical research methods: electron microscopy and X-ray analysis. Results of experimental research showed that the peat additives contribute to improving of cement-sand mortar strength and hydrophysical properties.

  20. Additives for cement compositions based on modified peat

    Energy Technology Data Exchange (ETDEWEB)

    Kopanitsa, Natalya, E-mail: kopanitsa@mail.ru; Sarkisov, Yurij, E-mail: sarkisov@tsuab.ru; Gorshkova, Aleksandra, E-mail: kasatkina.alexandra@gmail.com; Demyanenko, Olga, E-mail: angel-n@sibmail.com [Tomsk State University of Architecture and Building, 2, Solyanaya sq., Tomsk, 634003 (Russian Federation)

    2016-01-15

    High quality competitive dry building mixes require modifying additives for various purposes to be included in their composition. There is insufficient amount of quality additives having stable properties for controlling the properties of cement compositions produced in Russia. Using of foreign modifying additives leads to significant increasing of the final cost of the product. The cost of imported modifiers in the composition of the dry building mixes can be up to 90% of the material cost, depending on the composition complexity. Thus, the problem of import substitution becomes relevant, especially in recent years, due to difficult economic situation. The article discusses the possibility of using local raw materials as a basis for obtaining dry building mixtures components. The properties of organo-mineral additives for cement compositions based on thermally modified peat raw materials are studied. Studies of the structure and composition of the additives are carried out by physicochemical research methods: electron microscopy and X-ray analysis. Results of experimental research showed that the peat additives contribute to improving of cement-sand mortar strength and hydrophysical properties.

  1. Software component composition based on ADL and Middleware

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    How to compose prefabricated components is a key issue in component-based reuse. Research on Software Architecture (SA) and Component-based Software Development (CBSD) provides two hopeful solutions from different perspectives. SA provides a top-down approach to realizing component-based reuse. However, it pays insufficient attention to the refinement and implementation of the architectural descriptions, and does not provide the necessary capability to automate the transformation or composition to form a final executable application. CBSD provides a bottom-up way by using existing middleware infrastructures. However, these technologies do not take into account the systematic methodology that can guide the CBSD process, especially the component composition at higher abstract levels. We argue that it is a natural solution to combine these two approaches.   In this paper, an architecture-based component composition approach is presented. In this way, SA description, using mapping rules and mini-tools to narrow the gap between design and implementation, is used as the blueprint and middleware technology as the runtime scaffold for component composition. Our approach presents an ADL, which supports user-defined connectors and has an extensible framework, to specify software architectures. To map a SA description into implementation, it is necessary to map it first to an OO design model described in UML, then to the final implementation. The architectural description can be mapped into source code or executable code by using some ORB conforming to CORBA standard. Also a toolkit is provided to support this approach efficiently.

  2. GEMBus based services composition platform for cloud PaaS

    NARCIS (Netherlands)

    Y. Demchenko; C. Ngo; P. Martínez-Julia; E. Torroglosa; M. Grammatikou; J. Jofre; S. Gheorghiu; J.A. Garcia-Espin; A.D. Perez-Morales; C. de Laat

    2012-01-01

    Cloud Platform as a Service (PaaS) provides an environment for creating and deploying applications using one of popular development platforms. This paper presents a practical solution for building a service composition platform based on the GEMBus (GEANT Multi-domain Bus) that extends the industry a

  3. MoSi2-Base Hybrid Composites from Aeroengine Applications

    Science.gov (United States)

    Hebsur, Mohan G.

    2000-01-01

    Addition of about 30 to 50 vol % of Si3N4 particulate to MoSi2 improved low temperature accelerated oxidation resistance by forming a Si2ON2 protective scale and thereby eliminated catastrophic 'pest failure'. The Si3N4 addition also improved the high temperature creep strength by nearly five orders of magnitude, doubled the room temperature toughness, and significantly lowered the CTE of the MoSi2 which eliminated matrix cracking in SCS-6 reinforced composites even after thermal cycling. The SCS-6 fiber reinforcement improved the room temperature fracture toughness by seven times and impact resistance by five times. The composite exhibited this excellent strength and toughness improvement up to 1673 K. More recently, tape casting was adopted as the preferred processing of MoSi2-base composites due to improved fiber spacing, ability to use small diameter fibers, and for lower cost. Good strength and toughness values were also obtained with fine diameter Hi-Nicalon tow fibers. These hybrid composites remain competitive with ceramic matrix composites as a replacement for Ni-base superalloys in aircraft engine applications.

  4. Effect of cyclic loading on microleakage of silorane based composite compared with low shrinkage methacrylate-based composites

    Science.gov (United States)

    Kermanshah, Hamid; Yasini, Esmail; Hoseinifar, Razieh

    2016-01-01

    Background: There are many concerns regarding the marginal seal of composite restorations, especially when composite restorations are subjected to cyclic loading. The aim of this study was to evaluate the effect of cyclic loading on the microleakage of silorane based composite compared with low shrinkage methacrylate-based composites in class V cavities. Materials and Methods: In this in vitro study, class V cavities were prepared on the facial and lingual surfaces of 48 human premolars (96 cavities). The teeth were randomly divided into four groups of 12 teeth (24 cavities) each and restored as follows: Group 1 (Siloran System Adhesive + Filtek P90), Group 2 (All Bond SE + Aelite LS Posterior), Group 3 (Futurabond NR + Grandio), and Group 4 (G-Bond + Kalore-GC). All the specimens were thermocycled for 2000 cycles (5-55°C) and then half of the specimens from each group, were Load cycled. All teeth were immersed in 0.5% basic fuchsine dye, sectioned, and observed under a stereomicroscope. Data were analyzed using Wilcoxon test, Kruskal–Wallis, and Mann–Whitney U-tests. P < 0.05 was considered as significant. Results: In both unloaded and loaded groups, no statistically significant differences were observed among four composites at the occlusal margin, but a significant difference in gingival microleakage was found between Aelite and silorane. Occlusal and gingival microleakage was not affected by cyclic loading in none of the four restorative materials. Conclusion: Silorane did not provide better marginal seal than the low shrinkage methacrylate-based composites (except Aelite). In addition, cyclic loading did not affect the marginal microleakage of evaluated composite restorations. PMID:27274348

  5. Heating of thermoplastic-based unidirectional composite prepregs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.; Weber, M.E.; Charrier, J.M. (McGill Univ., Montreal (Canada))

    1989-04-01

    Thermoplastic-based prepregs offer a potential for faster manufacture of composite products than with thermoset-based prepregs. The winding or controlled placement of thermoplastic-based prepreg tapes requires the rapid heating of the moving tape, just prior to its contact with the substrate on the mandrel. In the case of complex shapes, geometrical constraints and significant variations in tape speeds in the course of manufacture, make it particularly desirable to be able to model the heating process. A mathematical model and its experimental verification for convection/conduction heat transfer to and through either a homogeneous thermoplastic material, or thermoplastic-based unidirectional composites featuring glass, aramid and carbon fibers, is discussed. 12 refs.

  6. An Emotion-Based Method to Perform Algorithmic Composition

    OpenAIRE

    Huang, Chih-Fang; Lin, En-Ju

    2013-01-01

    The generative music using algorithmic composition techniques has been developed in many years. However it usually lacks of emotion-based mechanism to generate music with specific affective features. In this article the automated music algorithm will be performed based on Prof. Phil Winosr’s “MusicSculptor” software with proper emotion parameter mapping to drive the music content with specific context using various music pa-rameters distribution with different probability control, in order to...

  7. METAL MATRIX COMPOSITES BASED ON ALUMINIUM LITHIUM AND SILICON CARBIDE

    OpenAIRE

    White, J.; Hughes, I; Willis, T.; Jordan, R.

    1987-01-01

    The present study tests the feasibility of producing metal matrix composites based on aluminium-lithium alloys. The first step in this process has been to produce an MMC based on 8090 with SiC. This has been successfully produced by Alcan International using the "Osprey" spray deposition process. The raw billets have been processed initially by extrusion. The tensile properties of this material have been determined and the strength compares favourably with DC cast alloys. Modulus is improved ...

  8. High efficiency tantalum-based ceramic composite structures

    Science.gov (United States)

    Stewart, David A. (Inventor); Leiser, Daniel B. (Inventor); DiFiore, Robert R. (Inventor); Katvala, Victor W. (Inventor)

    2010-01-01

    Tantalum-based ceramics are suitable for use in thermal protection systems. These composite structures have high efficiency surfaces (low catalytic efficiency and high emittance), thereby reducing heat flux to a spacecraft during planetary re-entry. These ceramics contain tantalum disilicide, molybdenum disilicide and borosilicate glass. The components are milled, along with a processing aid, then applied to a surface of a porous substrate, such as a fibrous silica or carbon substrate. Following application, the coating is then sintered on the substrate. The composite structure is substantially impervious to hot gas penetration and capable of surviving high heat fluxes at temperatures approaching 3000.degree. F. and above.

  9. Reinforcement Learning Based Web Service Compositions for Mobile Business

    Science.gov (United States)

    Zhou, Juan; Chen, Shouming

    In this paper, we propose a new solution to Reactive Web Service Composition, via molding with Reinforcement Learning, and introducing modified (alterable) QoS variables into the model as elements in the Markov Decision Process tuple. Moreover, we give an example of Reactive-WSC-based mobile banking, to demonstrate the intrinsic capability of the solution in question of obtaining the optimized service composition, characterized by (alterable) target QoS variable sets with optimized values. Consequently, we come to the conclusion that the solution has decent potentials in boosting customer experiences and qualities of services in Web Services, and those in applications in the whole electronic commerce and business sector.

  10. FUZZY RELIABILITY-BASED OPTIMUM DESIGN OF LAMINATED COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Wei Junhong; Chen Jianqiao; Ge Rui

    2006-01-01

    In conventional reliability-based optimum design of structures, the reliability is computed based on the probability assumption, and the design objective and constraint are considered as deterministic ones. In many cases, however, there exist some fuzzy factors in the design objective and constraint functions. In this paper, the fuzzy reliability and fuzzy constraint are introduced to establish the fuzzy reliability-based optimum model for laminated composites. The examples show that the method developed in this paper can give consideration to both the reliability demand and the economic aspect of a structure. Since the fuzzy reliability-based optimum design structural reliability and bring us an alternative optimum design idea.

  11. Investigation of cement based composites made with recycled rubber aggregate

    Directory of Open Access Journals (Sweden)

    Jevtić Dragica Lj.

    2012-01-01

    Full Text Available The results of experimental investigations performed on cement based composites made with addition of recycled rubber as a partial replacement of natural river aggregate are presented in this paper. Different properties of cement based mortar were analyzed, both in fresh and in hardened state. Tested properties in the fresh state included: density, consistency and volume of entrained air. In the hardened state, the following properties were tested: density, mechanical properties (compressive and flexural strength, modulus of elasticity, adhesion to concrete substrate, water absorption, freeze-thaw resistance and ultrasonic pulse velocity. The obtained results indicate that recycled rubber can be successfully applied as a partial replacement of natural river aggregate in cement based composites, in accordance with the sustainable development concept. The investigation showed that physical-mechanical properties of cementituous composites depend to a great extent on the percentage of replacement of natural river aggregate with recycled rubber, especially when the density, strength, adhesion and freeze-thaw resistance are concerned. The best results were obtained in the freeze-thaw resistance of such composites.

  12. Structure formation and properties of molybdenum-base powder composites

    Energy Technology Data Exchange (ETDEWEB)

    Minakova, R.V.; Kresanova, A.P.; Lesnik, N.D.; Malyshenko, A.A.; Antonov, S.O.

    1988-07-01

    The purpose of this work was to investigate physicochemical conditions of formation and features of structure formation of molybdenum-base composites and, in particular, to study the adhesion characteristics and features of contact interaction in Mo-Cu-Ni(Co) systems, to investigate the distribution of the basic elements and impurities, the phase composition, the structure, and certain properties of the materials and parts. A combination of methods was used including x-ray spectral microanalysis, Auger spectroscopy, x-ray diffraction phase and structure analysis, microhardness and hot hardness methods, scanning electron microscopy, and metallography by optical microscopy. The influence of hot hardness of the composite was selected as the criterion of evaluation and it was found that increases in hot hardness and in high-temperature oxidation increased the life and service properties of electrodes used for spot welding and brazing in production.

  13. Modifying the acoustic impedance of polyurea-based composites

    Science.gov (United States)

    Nantasetphong, Wiroj; Amirkhizi, Alireza V.; Jia, Zhanzhan; Nemat-Nasser, Sia

    2013-04-01

    Acoustic impedance is a material property that depends on mass density and acoustic wave speed. An impedance mismatch between two media leads to the partial reflection of an acoustic wave sent from one medium to another. Active sonar is one example of a useful application of this phenomenon, where reflected and scattered acoustic waves enable the detection of objects. If the impedance of an object is matched to that of the surrounding medium, however, the object may be hidden from observation (at least directly) by sonar. In this study, polyurea composites are developed to facilitate such impedance matching. Polyurea is used due to its excellent blast-mitigating properties, easy casting, corrosion protection, abrasion resistance, and various uses in current military technology. Since pure polyurea has impedance higher than that of water (the current medium of interest), low mass density phenolic microballoon particles are added to create composite materials with reduced effective impedances. The volume fraction of particles is varied to study the effect of filler quantity on the acoustic impedance of the resulting composite. The composites are experimentally characterized via ultrasonic measurements. Computational models based on the method of dilute-randomly-distributed inclusions are developed and compared with the experimental results. These experiments and models will facilitate the design of new elastomeric composites with desirable acoustic impedances.

  14. Composites

    Science.gov (United States)

    Taylor, John G.

    The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

  15. The composites based on plasticized starch and carbon nanotubes.

    Science.gov (United States)

    Cheng, Jing; Zheng, Pengwu; Zhao, Feng; Ma, Xiaofei

    2013-08-01

    In this study, the nanocomposite films based on plasticized starch and modified-carbon nanotubes were prepared using a simple casting method. Carbon nanotubes (CNTs) were oxidized to prepare CNT oxide (OCNT) by Hummer's method, and OCNTs were reduced by glucose to obtain reduced CNT (RCNT). The thermogravimetric (TG) curves revealed that OCNTs and RCNTs contained about 15 and 8wt% oxygen-containing groups, respectively. The UV-vis spectra proved that CNTs with the aid of the dispersant TNWDIS, OCNTs and RCNTs possessed the good stability in water. As the fillers, CNTs, OCNTs and RCNTs were introduced into plasticized-starch (PS) matrix to obtain the composites. They had the obvious reinforcing effect on PS matrix. The composites containing 4wt% RCNT had the maximum tensile strength of 19.5MPa, in contrast to 3.89MPa of PS. Among of them, PS/CNT composites showed the best moisture resistance. And the PS-based CNT, OCNT and RCNT composites exhibited approximate electrical conductivities. PMID:23587994

  16. Synthetic heat carrier oil compositions based on polyalkylene glycols

    International Nuclear Information System (INIS)

    The results of syntheses of heat carrier oils based on polyalkylene glycols (PAGs) using suitable additives have been reported. Polyalkylene glycols have been prepared by heating diethylene glycol, propylene oxide, glycols, adipic acid and 2-ethyhexanol in the presence of KOH and stannyl octoate as catalyst in the molar ratio to give proper physical properties and viscosity-temperature index. The prepared PAGs have been taken as basic components for heat carrier oil compositions. In order to improve the thermal stability and viscosity indices, as well as other specifications, anti-oxidant and anti-foaming additives were added to the base material to reach optimum compositions. Thermal stability, mass loss on vaporization at 250 oC, 350 oC and changing the specifications after heating at 300 oC for 10 h have also been investigated. The obtained heat carrier oils showed comparable improved properties in comparison with commercially available heat carriers

  17. Smart Behavior of Carbon Fiber Reinforced Cement-based Composite

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The electrical characteristics of cement-based material can be remarkably improved by the addition of short carbon fibers.Carbon fiber reinforced cement composite (CFRC) is an intrinsically smart material that can sense not only the stress andstrain, but also the temperature. In this paper, variations of electrical resistivity with external applied load, and relationof thermoelectric force and temperature were investigated. Test results indicated that the electrical signal is related to theincrease in the material volume resistivity during crack generation or propagation and the decrease in the resistivity duringcrack closure. Moreover, it was found that the fiber addition increased the linearity and reversibility of the Seebeck effect inthe cement-based materials. The change of electrical characteristics reflects large amount of information of inner damage andtemperature differential of composite, which can be used for stress-strain or thermal self-monitoring by embedding it in theconcrete structures.

  18. Composite Scaffolds Based on Silver Nanoparticles for Biomedical Applications

    OpenAIRE

    Jenel Marian Patrascu; Ioan Avram Nedelcu; Maria Sonmez; Denisa Ficai; Anton Ficai; Bogdan Stefan Vasile; Camelia Ungureanu; Madalina Georgiana Albu; Bogdan Andor; Ecaterina Andronescu; Laura Cristina Rusu

    2015-01-01

    This paper presents the synthesis, characterisation, and in vitro testing of homogenous and heterogeneous materials containing silver nanoparticles (nanoAg). Three types of antiseptic materials based on collagen (COLL), hydroxyapatite (HA), and collagen/hydroxyapatite (COLL/HA) composite materials were obtained. The synthesis of silver nanoparticles was realized by chemical reaction as well as plasma sputtering deposition. The use of chemical reduction allows the synthesis of homogenous mater...

  19. Calcium phosphate-based ceramic and composite materials for medicine

    International Nuclear Information System (INIS)

    The topical problems in chemistry and technology of materials based on calcium phosphates aimed at both the replacement of damaged bone tissue and its regeneration are discussed. Specific features of the synthesis of nanocrystalline powders and the fabrication of ceramic implants are described. Advances in the development of porous scaffolds from resorbable and osteoconductive calcium phosphates and of hybrid composites that form the basis of bone tissue engineering are considered.

  20. A Nanocellulose Polypyrrole Composite Based on Microfibrillated Cellulose from Wood

    OpenAIRE

    Nyström, Gustav; Mihranyan, Albert; Razaq, Aamir; Lindström, Tom; Nyholm, Leif; Strømme, Maria

    2010-01-01

    It is demonstrated that it is possible to coat the individual fibers of wood-based nanocellulose with polypyrrole using in situ chemical polymerization to obtain an electrically conducting continuous high-surface-area composite. The experimental results indicate that the high surface area of the water dispersed material, to a large extent, is maintained upon normal drying without the use of any solvent exchange. Thus, the employed chemical polymerization of polypyrrole on the microfibrillated...

  1. ROMP-based polymer composites and biorenewable rubbers

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Wonje [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    This research is divided into two related topics. In the first topic, the synthesis and characterization of novel composite materials reinforced with MWCNTs by ring-opening metathesis polymerization (ROMP) is reported for two ROMP based monomers: dicyclopentadiene (DCPD) and 5-ethylidene-2-norbornene (ENB). Homogeneous dispersion of MWCNTs in the polymer matrices is achieved by grafting norbornene moieties onto the nanotube surface. For the DCPD-based system, the investigation of mechanical properties of the composites shows a remarkable increase of tensile toughness with just 0.4 wt % of functionalized MWCNTs (f-MWCNTs). To our knowledge, this represents the highest toughness enhancement efficiency in thermosetting composites ever reported. DMA results show that there is a general increase of thermal stability (rg) with the addition of f-MWCNTs, which means that covalently bonded f-MWCNTs can reduce the local chain mobility of the matrix by interfacial interactions. The ENB system also shows significant enhancement of the toughness using just 0.8 wt % f-MWCNTs. These results indicate that the ROMP approach for polyENB is also very effective. The second topic is an investigation of the biorenewable rubbers synthesized by the tandem ROMP and cationic polymerization. The resin consists of a norbornenyl-modified linseed oil and a norbornene diester. Characterization of the bio-based rubbers includes dynamic mechanical analysis, tensile testing, and thermogravimetric analysis. The experimental results show that there is a decrease in glass transition temperature and slight increase of elongation with increased diester loading.

  2. ROMP-based polymer composites and biorenewable rubbers

    Science.gov (United States)

    Jeong, Wonje

    This research is divided into two related topics. In the first topic, the synthesis and characterization of novel composite materials reinforced with MWCNTs by ring-opening metathesis polymerization (ROMP) is reported for two ROMP based monomers: dicyclopentadiene (DCPD) and 5-ethylidene-2-norbornene (ENB). Homogeneous dispersion of MWCNTs in the polymer matrices is achieved by grafting norbornene moieties onto the nanotube surface. For the DCPD-based system, the investigation of mechanical properties of the composites shows a remarkable increase of tensile toughness with just 0.4 wt % of functionalized MWCNTs (f-MWCNTs). To our knowledge, this represents the highest toughness enhancement efficiency in thermosetting composites ever reported. DMA results show that there is a general increase of thermal stability (T g) with the addition of f-MWCNTs, which means that covalently bonded f-MWCNTs can reduce the local chain mobility of the matrix by interfacial interactions. The ENB system also shows significant enhancement of the toughness using just 0.8 wt % f-MWCNTs. These results indicate that the ROMP approach for polyENB is also very effective. The second topic is an investigation of the biorenewable rubbers synthesized by the tandem ROMP and cationic polymerization. The resin consists of a norbornenyl-modified linseed oil and a norbornene diester. Characterization of the bio-based rubbers includes dynamic mechanical analysis, tensile testing, and thermogravimetric analysis. The experimental results show that there is a decrease in glass transition temperature and slight increase of elongation with increased diester loading.

  3. Gestalt compositionality and instruction-based meaning construction.

    Science.gov (United States)

    Col, Gilles; Aptekman, Jeanne; Girault, Stéphanie; Poibeau, Thierry

    2012-05-01

    We would like to propose a new model of meaning construction based on language comprehension considered as a dynamic process during which the meaning of each linguistic unit and the global meaning of the sentence are determined simultaneously. This model, which may be called "gestalt compositionality," is radically opposed to the classic compositional mechanism advocated by linguistic formalism based on the primacy of syntax. The process considers the syntactic structure of an utterance as the product of meaning construction rather than its source. The comprehension of an utterance is consequently directly based on the interaction between the different basic components of this utterance: lexical units, grammatical markers, positional relations between units, and more generally, basic "constructions" in the sense of Construction Grammar. Thus, meaning is really the result of a gestalt compositional process insomuch as the contribution of each basic component depends on the contribution of the other components present in the utterance. We show a first attempt at modeling from French and English examples.

  4. Investigations on cementitious composites based on rubber particle waste additions

    Directory of Open Access Journals (Sweden)

    Glaucio Laun Nacif

    2013-04-01

    Full Text Available The amount of waste rubber has gradually increased over recent years because of over-growing use of rubber products. The disposal of waste rubber has caused serious environmental problems. The incorporation of recycled materials into cementitious composites is a feasible alternative that has gained ground in civil construction. The performance of such materials is much affected not only by the rubber addition, but also the particle size which has been controversially reported in the literature. In order to investigate the single effect of rubber particles into cement based materials, rubber cementitious composites were prepared with no silica particle additions. A full factorial design has been conducted to assess the influence of the rubber particle size (0.84/0.58 mm and 0.28/0.18 mm; mass fraction used (5, 15 and 30%; and water/cement ratio (0.35 and 0.50 on the physic-mechanical properties of the composites. The materials were characterized through apparent density, porosity, compressive strength, flexural strength, modulus of elasticity and microstructural analysis. The interactions of rubber particle size, rubber fraction and water/cement ratio affected significantly the density and compressive strength of the composites. The apparent porosity was influenced mainly by the rubber particle size. The flexural strength was affected by the main factors and the modulus of elasticity was affected by the interaction factors rubber particle size and fraction, and rubber fraction and w/c ratio.

  5. Experimentally-based relaxation modulus of polyurea and its composites

    Science.gov (United States)

    Jia, Zhanzhan; Amirkhizi, Alireza V.; Nantasetphong, Wiroj; Nemat-Nasser, Sia

    2016-06-01

    Polyurea is a block copolymer that has been widely used in the coating industry as an abrasion-resistant and energy-dissipative material. Its mechanical properties can be tuned by choosing different variations of diamines and diisocyanates as well as by adding various nano- and micro-inclusions to create polyurea-based composites. Our aim here is to provide the necessary experimentally-based viscoelastic constitutive relations for polyurea and its composites in a format convenient to support computational studies. The polyurea used in this research is synthesized by the reaction of Versalink P-1000 (Air Products) and Isonate 143L (Dow Chemicals). Samples of pure polyurea and polyurea composites are fabricated and then characterized using dynamic mechanical analysis (DMA). Based on the DMA data, master curves of storage and loss moduli are developed using time-temperature superposition. The quality of the master curves is carefully assessed by comparing with the ultrasonic wave measurements and by Kramers-Kronig relations. Based on the master curves, continuous relaxation spectra are calculated, then the time-domain relaxation moduli are approximated from the relaxation spectra. Prony series of desired number of terms for the frequency ranges of interest are extracted from the relaxation modulus. This method for developing cost efficient Prony series has been proven to be effective and efficient for numerous DMA test results of many polyurea/polyurea-based material systems, including pure polyurea with various stoichiometric ratios, polyurea with milled glass inclusions, polyurea with hybrid nano-particles and polyurea with phenolic microbubbles. The resulting viscoelastic models are customized for the frequency ranges of interest, reference temperature and desired number of Prony terms, achieving both computational accuracy and low cost. The method is not limited to polyurea-based systems. It can be applied to other similar polymers systems.

  6. Paper-based ultracapacitors with carbon nanotubes-graphene composites

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian, E-mail: lijian@gwu.edu, E-mail: keidar@gwu.edu; Cheng, Xiaoqian; Brand, Cameron; Shashurin, Alexey; Keidar, Michael, E-mail: lijian@gwu.edu, E-mail: keidar@gwu.edu [Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052 (United States); Sun, Jianwei; Reeves, Mark [Department of Physics, The George Washington University, Washington, DC 20052 (United States)

    2014-04-28

    In this paper, a paper-based ultracapacitors were fabricated by the rod-rolling method with the ink of carbon nanomaterials, which were synthesized by arc discharge under various magnetic conditions. Composites of carbon nanostructures, including high-purity single-walled carbon nanotubes (SWCNTs) and graphene flakes were synthesized simultaneously in a magnetically enhanced arc. These two nanostructures have promising electrical properties and synergistic effects in the application of ultracapacitors. Scanning electron microscope, transmission electron microscope, and Raman spectroscopy were employed to characterize the properties of carbon nanostructures and their thin films. The sheet resistance of the SWCNT and composite thin films was also evaluated by four-point probe from room temperature to the cryogenic temperature as low as 90 K. In addition, measurements of cyclic voltammetery and galvanostatic charging/discharging showed the ultracapacitor based on composites possessed a superior specific capacitance of up to 100 F/g, which is around three times higher than the ultracapacitor entirely fabricated with SWCNT.

  7. SWSCF: A Semantic-based Web Service Composition Framework

    Directory of Open Access Journals (Sweden)

    Jianqiang Hu

    2009-06-01

    Full Text Available Web service composition is gaining a considerable momentum as an approach to the effective integration of distributed, heterogeneous, and autonomous application. Current composed service processes are mostly generated in the syntactic level and in a manual way. The limitation of the approach is that it does not allow business to dynamic change partners and services. In order to avoid this disadvantage, it is critical to map complex business from abstract process to executable flows according to application domain semantics and dynamic business requirements. In this paper, we first present a semantic-based Web service composition framework called SWSCF based on both semantic process recommendation and semantic matchmaking. Then, we analyze some key technologies including: (1 Introducing hierarchical activity mechanism for dynamic decomposition of business requirements to find a suitable semantic process template; (2 Searching and selecting service chain to match a semantic activity template which is used to specify an abstract activity; (3 Devising heterogeneous message transforming mechanism to eliminate the incompatible message types during generating data flow of an executable process. Furthermore, by comparison with some service composition frameworks, we prove SWSCF to be more flexible and effective.

  8. On Sliding Friction of PEEK Based Composite Coatings

    Institute of Scientific and Technical Information of China (English)

    H.Liao; G.Zhang; C.Mateus; H.Li; C.Coddet

    2004-01-01

    Polyetheretherketone (PEEK) based composite materials become of great interest to applications as bearing and slider materials due to their excellent tribological performance. In present work, graphite and MoS2(7%,wt) filled PEEK coatings were prepared using serigraph technique. Employing a uniform design experiment, the friction behavior of the composite coatings was systematically investigated under dry sliding conditions on a ball-on-disc arrangement. The evolution mechanism of coating friction coefficient was discussed. Correlation of coatings friction coefficient with sliding velocity and applied load was accomplished using stepwise regression method. The results indicate that friction coefficients of PEEK+MoS2 and PEEK+graphite coating decrease while increasing applied load. Moreover, friction coefficient of PEEK+MoS2 coating increases with increasing sliding velocity.

  9. Feasibility and Scaling of Composite Based Additive Manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Nuttall, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, Xun [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kunc, Vlastimil [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Love, Lonnie J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-04-27

    Engineers and Researchers at Oak Ridge National Lab s Manufacturing Demonstration Facility (ORNL MDF) collaborated with Impossible Objects (IO) in the characterization of PEEK infused carbon fiber mat manufactured by means of CBAM composite-based additive manufacturing, a first generation assembly methodology developed by Robert Swartz, Chairman, Founder, and CTO of Impossible Objects.[1] The first phase of this project focused on demonstration of CBAM for composite tooling. The outlined steps focused on selecting an appropriate shape that fit the current machine s build envelope, characterized the resulting form, and presented next steps for transitioning to a Phase II CRADA agreement. Phase I of collaborative research and development agreement NFE-15-05698 was initiated in April of 2015 with an introduction to Impossible Objects, and concluded in March of 2016 with a visitation to Impossible Objects headquarters in Chicago, IL. Phase II as discussed herein is under consideration by Impossible Objects as of this writing.

  10. On Sliding Friction of PEEK Based Composite Coatings

    Institute of Scientific and Technical Information of China (English)

    H. Liao; G. Zhang; C. Mateus; H. Li; C. Coddet

    2004-01-01

    Polyetheretherketone (PEEK) based composite materials become of great interest to applications as bearing and slider materials due to their excellent tribological performance. In present work, graphite and MoS2 (7%, wt) filled PEEK coatings were prepared using serigraph technique. Employing a uniform design experiment, the friction behavior of the composite coatings was systematically investigated under dry sliding conditions on a ball-on-disc arrangement. The evolution mechanism of coating friction coefficient was discussed. Correlation of coatings friction coefficient with sliding velocity and applied load was accomplished usingstepwise regression method. The results indicate that friction coefficients of PEEK + MoS2 and PEEK + graphite coating decrease while increasing applied load. Moreover, friction coefficient of PEEK + MoS2 coating increases with increasing sliding velocity.

  11. FLAMMABILITY OF ARALDITE BASED COMPOSITE MIXED WITH INORGANIC RETARDANTS

    Directory of Open Access Journals (Sweden)

    ALI I. AL-MOSAWI

    2012-10-01

    Full Text Available Flammability characteristics of araldite based composite mixed with inorganic hybrid flame retardant represent zinc borate - antimony trioxide as a surface layer(4mm thickness have been studied by thermal erosion test . Antimony trioxide was added to zinc borate with various amounts (10%,20% and 30% to forming a hybrid flame retardant for enhance the action of this material to react flame . The result composite material was exposed to a direct flame generated from Oxyacetylene torch (3000ºC with different flame exposure intervals (10,20mm, and studies the range of resistance of retardant material layer to the flames and protected the substrate. The optimum results were with large percentage from protective layer which is zinc borate-30% antimony trioxide and large exposed distance.

  12. Graph based E-Government web service composition

    CERN Document Server

    Elmaghraoui, Hajar; Chiadmi, Dalila; Benhlima, Laila

    2011-01-01

    Nowadays, e-government has emerged as a government policy to improve the quality and efficiency of public administrations. By exploiting the potential of new information and communication technologies, government agencies are providing a wide spectrum of online services. These services are composed of several web services that comply with well defined processes. One of the big challenges is the need to optimize the composition of the elementary web services. In this paper, we present a solution for optimizing the computation effort in web service composition. Our method is based on Graph Theory. We model the semantic relationship between the involved web services through a directed graph. Then, we compute all shortest paths using for the first time, an extended version of the Floyd-Warshall algorithm.

  13. Hybrid Composites Based on Carbon Fiber/Carbon Nanofilament Reinforcement

    Directory of Open Access Journals (Sweden)

    Mehran Tehrani

    2014-05-01

    Full Text Available Carbon nanofilament and nanotubes (CNTs have shown promise for enhancing the mechanical properties of fiber-reinforced composites (FRPs and imparting multi-functionalities to them. While direct mixing of carbon nanofilaments with the polymer matrix in FRPs has several drawbacks, a high volume of uniform nanofilaments can be directly grown on fiber surfaces prior to composite fabrication. This study demonstrates the ability to create carbon nanofilaments on the surface of carbon fibers employing a synthesis method, graphitic structures by design (GSD, in which carbon structures are grown from fuel mixtures using nickel particles as the catalyst. The synthesis technique is proven feasible to grow nanofilament structures—from ethylene mixtures at 550 °C—on commercial polyacrylonitrile (PAN-based carbon fibers. Raman spectroscopy and electron microscopy were employed to characterize the surface-grown carbon species. For comparison purposes, a catalytic chemical vapor deposition (CCVD technique was also utilized to grow multiwall CNTs (MWCNTs on carbon fiber yarns. The mechanical characterization showed that composites using the GSD-grown carbon nanofilaments outperform those using the CCVD-grown CNTs in terms of stiffness and tensile strength. The results suggest that further optimization of the GSD growth time, patterning and thermal shield coating of the carbon fibers is required to fully materialize the potential benefits of the GSD technique.

  14. Hybrid Aluminum Composite Materials Based on Carbon Nanostructures

    Directory of Open Access Journals (Sweden)

    Tatiana S. Koltsova

    2015-09-01

    Full Text Available We investigated formation of carbon nanofibers grown by chemical deposition (CVD method using an acetylene-hydrogen mixture on the surface of micron-sized aluminum powder particles. To obtain uniform distribution of the carbon nanostructures on the particles we deposited nickel catalyst on the surface by spraying from the aqueous solution of nickel nitrate. It was found that increasing the time of the synthesis lowers the rate of growth of carbon nanostructures due to the deactivation of the catalyst. The Raman spectroscopy measurements confirm the presence of disordered carbon corresponding to CNFs in the specimen. X-ray photoelectron spectroscopy showed the presence of aluminum carbide in the hot pressed samples. An aluminum composite material prepared using 1 wt.% CNFs obtained by uniaxial cold pressing and sintering showed 30% increase in the hardness compared to pure aluminum, whereas the composites prepared by hot pressing showed 80% increase in the hardness. Composite materials have satisfactory ductility. Thus, the aluminum based material reinforced with carbon nanostructures should be appropriate for creating high-strength and light compacts for aerospace and automotive applications and power engineering.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7355

  15. Graphene-Based Bionic Composites with Multifunctional and Repairing Properties.

    Science.gov (United States)

    Valentini, L; Bittolo Bon, S; Signetti, S; Pugno, N M

    2016-03-01

    In this work, a novel bionic composite inspired by the concept of yeast fermentation has been proposed. It was observed that the addition of graphene nanoplatelets during the fermentation of extract of Saccharomyces cerevisiae fungi allows coupling of the graphene sheets to the yeast cell wall. This process resulted in the formation of a composite film with improved mechanical and electrical properties along with the capability of converting the light stimulus in the electrical signal. The mechanical properties of the prepared composites, namely, the fracture strength and Young's modulus, were studied via numerical simulations and are related to the properties of the constituent phases via rules of mixture. Finally, it was observed that graphene nanoplatelets, added to the nutrient broth, were able to reassemble onto the stressed cell surface and repair the surface cracking, partially restoring the pristine electrical and mechanical properties. The method reported here may find potential application in the development of self-healable bioelectronic devices and microorganism-based strain and chemical biosensors.

  16. Investigation of composite materials using SLM-based phase retrieval.

    Science.gov (United States)

    Agour, Mostafa; Falldorf, Claas; Bergmann, Ralf B

    2013-07-01

    We present a robust method to inspect a typical composite material constructed of carbon fiber reinforced plastic (CFRP). It is based on optical surface contouring using the spatial light modulator (SLM)-based phase retrieval technique. The method utilizes multiple intensity observations of the wave field, diffracted by the investigated object, captured at different planes along the optical axis to recover the phase information across the object plane. The SLM-based system allows for the recording of the required consecutive intensity measurements in various propagation states across a common recording plane. This overcomes the mechanical shifting of a camera sensor required within the capturing process. In contrast to existing phase retrieval approaches, the measuring time is considerably reduced, since the switching time of the SLM is less than 50 ms. This enables nondestructive testing under thermal load. Experimental results are presented that demonstrate the approach can be used to assess structural properties of technical components made from CFRP.

  17. Investigation of composite materials using SLM-based phase retrieval.

    Science.gov (United States)

    Agour, Mostafa; Falldorf, Claas; Bergmann, Ralf B

    2013-07-01

    We present a robust method to inspect a typical composite material constructed of carbon fiber reinforced plastic (CFRP). It is based on optical surface contouring using the spatial light modulator (SLM)-based phase retrieval technique. The method utilizes multiple intensity observations of the wave field, diffracted by the investigated object, captured at different planes along the optical axis to recover the phase information across the object plane. The SLM-based system allows for the recording of the required consecutive intensity measurements in various propagation states across a common recording plane. This overcomes the mechanical shifting of a camera sensor required within the capturing process. In contrast to existing phase retrieval approaches, the measuring time is considerably reduced, since the switching time of the SLM is less than 50 ms. This enables nondestructive testing under thermal load. Experimental results are presented that demonstrate the approach can be used to assess structural properties of technical components made from CFRP. PMID:23811877

  18. Investigating the possibility of using new wood-based composite materials in staircase design

    OpenAIRE

    Jokinen, Tatu

    2014-01-01

    Wooden staircases are made with similar solid wood design decades. Wood-based composites have replaced most of solid wood in furniture but not in the staircases. Wood-based composites have several problems that need to be solved before they can be used for manufacturing staircase. Few of the using possibilities are investigated in thesis. This thesis has two focus areas of how to increasing use of wood-based composites in staircases. First, wood-based composite materials are increasing su...

  19. Thermoelectric study of INSB secondary phase based nano composite materials

    Science.gov (United States)

    Zhu, Song

    reasonably narrow band gap (˜0.17 eV at 300 K). In this dissertation, I experimentally investigate whether InSb could be a "good" nano-secondary phase in two thermoelectric bulk matrix materials, FeSb2 and half-Heusler compounds. In these in situ formed nano-composites, three mechanisms are utilized to decouple the otherwise adversely correlated Seebeck coefficient (alpha), electrical conductivity (sigma), and thermal conductivity (kappa). First, low energy carriers will be filtered out via the carrier energy filtering effect, enhancing the Seebeck coefficient without degrading the power factor (PF= alpha 2sigma). Second, high mobility carriers from the InSb nano-inclusions will be injected to the system to increase the electrical conductivity. Last, the numerous grain boundaries present in nano-composites allow for strong phonon scattering so as to reduce the thermal conductivity. After the initial in situ synthesis of nano-composites with the optimized composition, further nano-structuring processes are applied in the samples of FeSb2 with 0.5% atomic ratio of InSb. The results indicate that not all nano-structures are thermoelectrically favorable, multi-scale microstructures with the length scale comparable with the phonon mean free path are needed to effectively scatter phonons over a wide range of wavelength. In summary, the successful combination of the carrier energy filtering effect, high mobility carrier injection effect, and strong phonon scattering effect in the in situ synthesized FeSb2-InSb and half-Heusler-InSb nano-composites leads to a significantly enhanced ZT. This approach of in situ formation of nano-composites based on InSb secondary nano-phase may also be applied to other thermoelectric materials.

  20. Increased complexity of gene structure and base composition in vertebrates

    Institute of Scientific and Technical Information of China (English)

    Ying Wu; Huizhong Yuan; Shengjun Tan; Jian-Qun Chen; Dacheng Tian; Haiwang Yang

    2011-01-01

    How the structure and base composition of genes changed with the evolution of vertebrates remains a puzzling question. Here we analyzed 895 orthologous protein-coding genes in six multicellular animals: human, chicken, zebrafish, sea squirt, fruit fly, and worm. Our analyses reveal that many gene regions, particularly intron and 3' UTR, gradually expanded throughout the evolution of vertebrates from their invertebrate ancestors, and that the number of exons per gene increased. Studies based on all protein-coding genes in each genome provide consistent results.We also find that GC-content increased in many gene regions (especially 5' UTR) in the evolution of endotherms, except in coding-exons.Analysis of individual genomes shows that 3′ UTR demonstrated stronger length and CC-content correlation with intron than 5' UTR, and gene with large intron in all six species demonstrated relatively similar GC-content. Our data indicates a great increase in complexity in vertebrate genes and we propose that the requirement for morphological and functional changes is probably the driving force behind the evolution of structure and base composition complexity in multicellular animal genes.

  1. PREPARATION OF A LIGNIN-BASED COMPOSITE AND ITS PROPERTIES

    OpenAIRE

    Jian Li; Shujun Li; Haigang Wang; Yang Yang; Guowan Guo

    2011-01-01

    Enzymatic hydrolysis (EH) lignin was modified with formaldehyde. TG-DSC and PY-GC-MS analysis methods were adopted to characterize the differences between EH lignin and the modified lignin. The modified lignin was then mixed with wood sawdust and made into a lignin-based composite under the following conditions: pressure of 2 to 5 MPa, temperature of 175 to 190 oC, and the modified lignin dosage of 20% to 70%. The effects of pressure, temperature, and the modified lignin dosage on the propert...

  2. A four-state memory cell based on magnetoelectric composite

    Institute of Scientific and Technical Information of China (English)

    SHI Zhan; WANG CuiPing; LIU XinJun; NAN OeWen

    2008-01-01

    A four-state memory can store four states in each memory cell. We designed a four-state memory cell using Co/PZT magnetoelectric composite and observed a broad magnetoelectric hysteretic output loop on applying magnetic field. Based on magnetoelectric hysteresis, we developed a read method by ap-plying a bias magnetic field on the memory cell. Results gave clearly four-state signals of 15.8, -4.4, 5.5 and -11.3 μV, which demonstrated the feasibility of our design.

  3. Electrodeposition of nickel-based composite coatings for tribological applications

    OpenAIRE

    He, Yang

    2015-01-01

    The purpose of this research is to study, evaluate, and compare the different electro deposition processes for producing nickel-based composite coatings for application in tribology, including: Ni/BMA luminescent coating, Ni-P/MoS2 and Ni-P/WS2 self-lubricating coatings. In the first part, a new luminescent Ni coating containing an embedded, blue emitting rare-earth mixed metal oxide (BaMgAl11O17:Eu2+) BAM was electrodeposited successfully from an aqueous electrolyte. Two types of surfac...

  4. Recent advances on polyoxometalate-based molecular and composite materials.

    Science.gov (United States)

    Song, Yu-Fei; Tsunashima, Ryo

    2012-11-21

    Polyoxometalates (POMs) are a subset of metal oxides with unique physical and chemical properties, which can be reliably modified through various techniques and methods to develop sophisticated materials and devices. In parallel with the large number of new crystal structures reported in the literature, the application of these POMs towards multifunctional materials has attracted considerable attention. This critical review summarizes recent progress on POM-based molecular and composite materials, and particularly highlights the emerging areas that are closely related to surface, electronic, energy, environment, life science, etc. (171 references). PMID:22850732

  5. Collision-resistant hash function based on composition of functions

    CERN Document Server

    Ndoundam, Rene

    2011-01-01

    cryptographic hash function is a deterministic procedure that compresses an arbitrary block of numerical data and returns a fixed-size bit string. There exist many hash functions: MD5, HAVAL, SHA, ... It was reported that these hash functions are not longer secure. Our work is focused in the construction of a new hash function based on composition of functions. The construction used the NP-completeness of Three-dimensional contingency tables and the relaxation of the constraint that a hash function should also be a compression function.

  6. Development of a new test method for Mineral Based Composites

    DEFF Research Database (Denmark)

    Täljsten, Björn; Orosz, Katalin

    2008-01-01

    The well-known wedge splitting test, often used for characterizing brittle materials has been modified and adapted to testing MBC-reinforced concrete under splitting load. MBC (Mineral Based Composites) is a newly developed strengthening system for existing concrete structures where FRPs, mainly...... CFRP grids are externally bonded to the concrete surface by means of cementitious bonding agents. Crack development, crack patterns, crack opening displacement (COD) versus splitting load and fracture energy are investigated and evaluated. Development of a suitable test specimen and test setup has been...

  7. Toughening of wood plastic composite based on X-PP

    Science.gov (United States)

    Meekum, U.; Khongrit, A.

    2016-03-01

    Wood plastic composite(WPC) based on crosslinked polypropylene(X-PP)/wood flour was explored. The peroxide/silane was used as crosslinking system. The sauna incubation under moisture saturated oven was applied to accelerate the competition of the siloxy/moisture networking reaction. There were three parts of the research work; design of experiment, toughening of WPC and the effect of peroxide, silane and PP copolymer on properties of the WPC, respectively. In this published work, the toughness improvement of the composite was focused. Ultra-high molecular weight polyethylene (UHMWPE) and Ethylene propylene diene terpolymer(EPDM) were employed to improve impact strength via blending with x-PP matrix. Composites were compounded into pellets by co-rotational twin screw extruder and test specimens were prepared by injection molding. Sauna incubation at 105°C for 12 hrs in oven chamber was performed to accelerate the final silane condensation crosslink reaction. MFI, impact strength, flexural properties and heat deflection temperature measurement were conducted. Impact strength, HDT and flexural modulus were improved with increasing UHMWPE content, and the optimal values around 5-10 phr of UHMWPE were achieved. Addition of EPDM elastomer to the matrix blends, reduced flexural strength and modulus but increased impact strength. While incorporation of EPDM into the PP/UHMWPE blends was exhibited much higher impact strength than that of the PP/UHMWPE binary blends. Silane crosslinked through sauna treatment improved the impact strength. HDT were also much risen for the crosslinked composite comparing with the non-crosslinked one.

  8. Capacitance-based damage detection sensing for aerospace structural composites

    Science.gov (United States)

    Bahrami, P.; Yamamoto, N.; Chen, Y.; Manohara, H.

    2014-04-01

    Damage detection technology needs improvement for aerospace engineering application because detection within complex composite structures is difficult yet critical to avoid catastrophic failure. Damage detection is challenging in aerospace structures because not all the damage detection technology can cover the various defect types (delamination, fiber fracture, matrix crack etc.), or conditions (visibility, crack length size, etc.). These defect states are expected to become even more complex with future introduction of novel composites including nano-/microparticle reinforcement. Currently, non-destructive evaluation (NDE) methods with X-ray, ultrasound, or eddy current have good resolutions (analysis currently requires excessive wiring and complex signal analysis. Here, we present a capacitance sensor-based, structural defect detection technology with improved sensing capability. Thin dielectric polymer layer is integrated as part of the structure; the defect in the structure directly alters the sensing layer's capacitance, allowing full-coverage sensing capability independent of defect size, orientation or location. In this work, capacitance-based sensing capability was experimentally demonstrated with a 2D sensing layer consisting of a dielectric layer sandwiched by electrodes. These sensing layers were applied on substrate surfaces. Surface indentation damage (~1mm diameter) and its location were detected through measured capacitance changes: 1 to 250 % depending on the substrates. The damage detection sensors are light weight, and they can be conformably coated and can be part of the composite structure. Therefore it is suitable for aerospace structures such as cryogenic tanks and rocket fairings for example. The sensors can also be operating in space and harsh environment such as high temperature and vacuum.

  9. Composites

    OpenAIRE

    Zhao, Hanqing; Guo, Yuanzheng

    2014-01-01

    This thesis was a literature study concerning composites. With composites becoming increasingly popular in various areas such as aerospace industry and construction, the research about composites has a significant meaning accordingly. This thesis was aim at introducing some basic information of polymer matrix composites including raw mate-rial, processing, testing, applications and recycling to make a rough understanding of this kind of material for readers. Polymeric matrices, fillers,...

  10. Composition

    DEFF Research Database (Denmark)

    Bergstrøm-Nielsen, Carl

    2010-01-01

    New Year is an open composition to be realised by improvising musicians. It is included in "From the Danish Seasons" (see under this title). See more about my composition practise in the entry "Composition - General Introduction". This work is licensed under a Creative Commons "by-nc" License. You...

  11. Optimization Design System for Composite Structures Based on Grid Technology

    Institute of Scientific and Technical Information of China (English)

    CHENG Wen-yuan; CHANG Yan; CUI De-gang; XIE Xiang-hui

    2007-01-01

    To solve the topology optimization of complicated multi-objective continuous/discrete design variables in aircraft structure design, a Parallel Pareto Genetic Algorithm (PPGA) is presented based on grid platform in this paper. In the algorithm, the commercial finite element analysis (FEA) software is integrated as the calculating tool for analyzing the objective functions and the filter of Pareto solution set based on weight information is introduced to deal with the relationships among all objectives. Grid technology is utilized in PPGA to realize the distributed computations and the user interface is developed to realize the job submission and job management locally/remotely. Taking the aero-elastic tailoring of a composite wing for optimization as an example, a set of Pareto solutions are obtained for the decision-maker. The numerical results show that the aileron reversal problem can be solved by adding the limited skin weight in this system. The algorithm can be used to solve complicated topology optimization for composite structures in engineering and the computation efficiency can be improved greatly by using the grid platform that aggregates numerous idle resources.

  12. Piezoresistivity in Carbon Fiber Reinforced Cement Based Composites

    Institute of Scientific and Technical Information of China (English)

    Bing CHEN; Keru WU; Wu YAO

    2004-01-01

    The resu lts of some i nteresti ng investigation on the piezoresistivity of ca rbon fi ber reinforced cement based com posites (CFRC) are presented with the prospect of developing a new nondestructive testing method to assess the integrity of the composite. The addition of short carbon fibers to cement-based mortar or concrete improves the structural performance and at the same time significantly decreases the bulk electrical resistivity. This makes CFRC responsive to the smart behavior by measuring the resistance change with uniaxial pressure. The piezoresistivity of CFRC under different stress was studied, at the same time the damage occurring inner specimens was detected by acoustic emission as well. Test results show that there exists a marking pressure dependence of the conductivity in CFRC, in which the so-called negative pressure coefficient of resistive (NPCR) and positive pressure coefficient of resistive (PPCR) are observed under low and high pressure. Under constant pressures, time-dependent resistivity is an outstanding characteristic for the composites, which is defined as resistance creep. The breakdown and rebuild-up process of conductive network under pressure may be responsible for the pressure dependence of resistivity.

  13. -Ti-Based Homogeneous and Bi-layered Composites

    Science.gov (United States)

    Gupta, Neha; Parameswaran, Venkitanarayanan; Basu, Bikramjit

    2014-09-01

    The growing threats due to increased use of small-caliber armor piercing projectiles demand the development of new light-weight body armor materials. In this context, TiB2 appears to be a promising ceramic material. However, poor sinterability and low fracture toughness remain two major issues for TiB2. In order to address these issues together, Ti as a sinter-aid is used to develop TiB2-( x wt pct Ti), ( x = 10, 20) homogeneous composites and a bi-layered composite (BLC) with each layer having Ti content of 10 and 20 wt pct. The present study uniquely demonstrates the efficacy of two-stage spark plasma sintering route to develop dense TiB2-Ti composites with an excellent combination of nanoscale hardness (~36 GPa) and indentation fracture toughness (~12 MPa m1/2). In case of BLC, these properties are not compromised w.r.t. homogeneous composites, suggesting the retention of baseline material properties even in the bi-layer design due to optimal relief of residual stresses. The better indentation toughness of TiB2-(10 wt pct Ti) and TiB2-(20 wt pct Ti) composites can be attributed to the observed crack deflection/arrest, indicating better damage tolerance. Transmission electron microscope investigation reveals the presence of dense dislocation networks and deformation twins in α-Ti at the grain boundaries and triple pockets, surrounded by TiB2 grains. The dynamic strength of around 4 GPa has been measured using Split Hopkinson Pressure Bar tests in a reproducible manner at strain rates of the order of 600 s-1. The damage progression under high strain rate has been investigated by acquiring real time images for the entire test duration using ultra-high speed imaging. An attempt has been made to establish microstructure-property correlation and a simple analysis based on Mohr-Coulomb theory is used to rationalize the measured strength properties.

  14. Composite Scaffolds Based on Silver Nanoparticles for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Jenel Marian Patrascu

    2015-01-01

    Full Text Available This paper presents the synthesis, characterisation, and in vitro testing of homogenous and heterogeneous materials containing silver nanoparticles (nanoAg. Three types of antiseptic materials based on collagen (COLL, hydroxyapatite (HA, and collagen/hydroxyapatite (COLL/HA composite materials were obtained. The synthesis of silver nanoparticles was realized by chemical reaction as well as plasma sputtering deposition. The use of chemical reduction allows the synthesis of homogenous materials while the plasma sputtering deposition can be easily used for the synthesis of homogeneous and heterogeneous support. Based on the in vitro assays clear antiseptic activity against Escherichia coli was relieved even at low content of nanoAg (10 ppm.

  15. Review on Preservative Treatment and Decay Resistance of Wood-based Composites

    Institute of Scientific and Technical Information of China (English)

    LIU Zhi; CAO Jinzhen

    2006-01-01

    To extend the service life and explore the use of wood-based composites, it is quite necessary to improve the decay resistance of wood-based composites through preservative treatments. Researchers have studied the methods of preservative treatment and the decay resistance of treated wood-based composites. In this paper, the categories of wood-based composites are briefly summarized and the previous and present investigations on the preservative treatment and decay resistance of different categories of wood-based composites are introduced. Some problems are also put forward and suggestions are given for future studies.

  16. Preparation and characterization of a novel ionizing electromagnetic radiation shielding material: Hematite filled polyester based composites

    Science.gov (United States)

    Eren Belgin, E.; Aycik, G. A.; Kalemtas, A.; Pelit, A.; Dilek, D. A.; Kavak, M. T.

    2015-10-01

    Isophthalic polyester (PES) based and natural mineral (hematite) filled composites were prepared and characterized for ionizing electromagnetic radiation shielding applications. Density evaluation and microscopic studies of the composites were carried out. Shielding performances of the composites were investigated for three different IEMR energy regions as low, intermediate and high. The mass attenuation coefficient of the prepared composites reached 98% of the elemental lead. In addition, the studied composites were superior to lead by virtue of their non-toxic nature.

  17. Resonance-based bonding detection for piezoelectric fiber composites

    Science.gov (United States)

    Wang, Dwo-Wen; Yin, Ching-Chung

    2008-11-01

    A resonance-based method is presented to determine the bonding conditions of piezoelectric fiber composite (PFC) patches attached to host structures. The PFCs are used to be functional materials by applying voltage through the interdigital electrodes symmetrically aligned on opposite surfaces of the composite patches. Interfacial debonds usually degrade the function. Only the edge debonds are taken into account in this paper. A partially debonded patch bears an in-plane extensional vibration if the interdigital electrodes are excited by a sinusoidal voltage. Electric impedance of the PFC patch adhered on an aluminum plate was measured in a broad frequency range to seek the resonant frequencies. The modal characteristics depend on the size of debond, material properties of the PFC, and stiffness of remaining adhesive in front of the edge debond. Extensional vibration of an elastic sheet is characteristic of the resonant frequencies being inversely proportional to the debonding length. The lowest several modes are considered. Experimental results indicate that self-detecting progressive debonding between the PFC patch and the host plate is feasible.

  18. Reaction synthesis of Ni-Al based particle composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    SUSAN,DONALD F.; MISIOLEK,WOICECK Z.; MARDER,ARNOLD R.

    2000-02-11

    Electrodeposited metal matrix/metal particle composite (EMMC) coatings were produced with a nickel matrix and aluminum particles. By optimizing the process parameters, coatings were deposited with 20 volume percent aluminum particles. Coating morphology and composition were characterized using light optical microscopy (LOM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Differential thermal analysis (DTA) was employed to study reactive phase formation. The effect of heat treatment on coating phase formation was studied in the temperature range 415 to 1,000 C. Long-time exposure at low temperature results in the formation of several intermetallic phases at the Ni matrix/Al particle interfaces and concentrically around the original Al particles. Upon heating to the 500--600 C range, the aluminum particles react with the nickel matrix to form NiAl islands within the Ni matrix. When exposed to higher temperatures (600--1,000 C), diffusional reaction between NiAl and nickel produces ({gamma})Ni{sub 3}Al. The final equilibrium microstructure consists of blocks of ({gamma}{prime})Ni{sub 3}Al in a {gamma}(Ni) solid solution matrix, with small pores also present. Pore formation is explained based on local density changes during intermetallic phase formation and microstructural development is discussed with reference to reaction synthesis of bulk nickel aluminides.

  19. Proteomics based compositional analysis of complex cellulase-hemicellulase mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Chundawat, Shishir P.; Lipton, Mary S.; Purvine, Samuel O.; Uppugundla, Nirmal; Gao, Dahai; Balan, Venkatesh; Dale, Bruce E.

    2011-10-07

    Efficient deconstruction of cellulosic biomass to fermentable sugars for fuel and chemical production is accomplished by a complex mixture of cellulases, hemicellulases and accessory enzymes (e.g., >50 extracellular proteins). Cellulolytic enzyme mixtures, produced industrially mostly using fungi like Trichoderma reesei, are poorly characterized in terms of their protein composition and its correlation to hydrolytic activity on cellulosic biomass. The secretomes of commercial glycosyl hydrolase producing microbes was explored using a proteomics approach with high-throughput quantification using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Here, we show that proteomics based spectral counting approach is a reasonably accurate and rapid analytical technique that can be used to determine protein composition of complex glycosyl hydrolase mixtures that also correlates with the specific activity of individual enzymes present within the mixture. For example, a strong linear correlation was seen between Avicelase activity and total cellobiohydrolase content. Reliable, quantitative and cheaper analytical methods that provide insight into the cellulosic biomass degrading fungal and bacterial secretomes would lead to further improvements towards commercialization of plant biomass derived fuels and chemicals.

  20. Magnetoimpedance of cobalt-based amorphous ribbons/polymer composites

    Science.gov (United States)

    Semirov, A. V.; Derevyanko, M. S.; Bukreev, D. A.; Moiseev, A. A.; Kudryavtsev, V. O.; Safronov, A. P.

    2016-10-01

    The combined influence of the temperature, the elastic tensile stress and the external magnetic field on the total impedance and impedance components were studied for rapidly quenched amorphous Co75Fe5Si4B16 ribbons. Both as-cast amorphous ribbons and Co75Fe5Si4B16/polymer amorphous ribbon based composites were considered. Following polymer coverings were studied: modified rubber solution in o-xylene, solution of butyl methacrylate and methacrylic acid copolymer in isopropanol and solution of polymethylphenylsiloxane resin in toluene. All selected composites showed very good adhesion of the coverings and allowed to provide temperature measurements from 163 K up to 383 K under the applied deforming tensile force up to 30 N. The dependence of the modulus of the impedance and its components on the external magnetic field was influenced by the elastic tensile stresses and was affected by the temperature of the samples. It was shown that maximal sensitivity of the impedance and its components to the external magnetic field was observed at minimal temperature and maximal deforming force depended on the frequency of an alternating current.

  1. Copper-based Composite Materials Reinforced with Carbon Nanostructures

    Directory of Open Access Journals (Sweden)

    Tatiana Larionova

    2015-09-01

    Full Text Available The present work is devoted to development of high performance Cu-based material reinforced with carbon. For this purpose Cu-C composite powders were produced by one-step CVD process. The powders containing carbon nanofibers and graphene were subjected to compacting and analyzed. Mechanical properties of Cu-carbon nanofibers (CNFs and Cu-graphene composites were compared to traditional Cu-graphite and pure copper samples compacted under the same technology. Cu-CNFs material showed the best performance (1.7 times increase in the hardness compared to copper, that is primarily explained by the smallest matrix grain size, which growth is inhibited by the homogeneously dispersed CNFs. Friction coefficient of the Cu-(17-33vol.%CNF was found to be 9 times less than that of pure copper and coincides within the error with Cu-graphite, however the wear of Cu-33vol.%CNF reduced by more than 2 times over Cu-33vol.% graphite samples.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7348

  2. Microstructural and compositional analyses of GaN-based nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Pretorius, Angelika; Mueller, Knut; Rosenauer, Andreas [Section Electron Microscopy, Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen (Germany); Schmidt, Thomas; Falta, Jens [Section Surface Physics, Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen (Germany); Aschenbrenner, Timo; Yamaguchi, Tomohiro; Dartsch, Heiko; Hommel, Detlef [Section Semiconductor Epitaxy, Institute of Solid State Physics, University of Bremen, Otto-Hahn-Allee 1, 28359 Bremen (Germany); Kuebel, Christian [Institute of Nanotechnology, Karlsruher Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2011-08-15

    Composition and microstructure of GaN-based island structures and distributed Bragg reflectors (DBRs) were investigated with transmission electron microscopy (TEM). We analysed free-standing InGaN islands and islands capped with GaN. Growth of the islands performed by molecular beam epitaxy (MBE) and metal organic vapour phase epitaxy (MOVPE) resulted in different microstructures. The islands grown by MBE were plastically relaxed. Cap layer deposition resulted in a rapid dissolution of the islands already at early stages of cap layer growth. These findings are confirmed by grazing-incidence X-ray diffraction (GIXRD). In contrast, the islands grown by MOVPE relax only elastically. Strain state analysis (SSA) revealed that the indium concentration increases towards the tips of the islands. For an application as quantum dots, the islands must be embedded into DBRs. Structure and composition of Al{sub y}Ga{sub 1-y}N/GaN Bragg reflectors on top of an AlGaN buffer layer and In{sub x}Al{sub 1-x}N/GaN Bragg reflectors on top of a GaN buffer layer were investigated. Specifically, structural defects such as threading dislocations (TDs) and inversion domains (IDs) were studied, and we investigated thicknesses, interfaces and interface roughnesses of the layers. As the peak reflectivities of the investigated DBRs do not reach the theoretical predictions, possible reasons are discussed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Accurate phylogenetic classification of DNA fragments based onsequence composition

    Energy Technology Data Exchange (ETDEWEB)

    McHardy, Alice C.; Garcia Martin, Hector; Tsirigos, Aristotelis; Hugenholtz, Philip; Rigoutsos, Isidore

    2006-05-01

    Metagenome studies have retrieved vast amounts of sequenceout of a variety of environments, leading to novel discoveries and greatinsights into the uncultured microbial world. Except for very simplecommunities, diversity makes sequence assembly and analysis a verychallenging problem. To understand the structure a 5 nd function ofmicrobial communities, a taxonomic characterization of the obtainedsequence fragments is highly desirable, yet currently limited mostly tothose sequences that contain phylogenetic marker genes. We show that forclades at the rank of domain down to genus, sequence composition allowsthe very accurate phylogenetic 10 characterization of genomic sequence.We developed a composition-based classifier, PhyloPythia, for de novophylogenetic sequence characterization and have trained it on adata setof 340 genomes. By extensive evaluation experiments we show that themethodis accurate across all taxonomic ranks considered, even forsequences that originate fromnovel organisms and are as short as 1kb.Application to two metagenome datasets 15 obtained from samples ofphosphorus-removing sludge showed that the method allows the accurateclassification at genus level of most sequence fragments from thedominant populations, while at the same time correctly characterizingeven larger parts of the samples at higher taxonomic levels.

  4. Carbon nanotube-cuprous oxide composite based pressure sensors

    Institute of Scientific and Technical Information of China (English)

    Kh. S. Karimov; Muhammad Tariq Saeed Chani; Fazal Ahmad Khalid; Adam Khan; Rahim Khan

    2012-01-01

    In this paper,we present the design,the fabrication,and the experimental results of carbon nanotube (CNT) and Cu2O composite based pressure sensors.The pressed tablets of the CNT-Cu2O composite are fabricated at a pressure of 353 MPa.The diameters of the multiwalled nanotubes (MWNTs) are between 10 nm and 30 nm.The sizes of the Cu2O micro particles are in the range of 3-4 μrn.The average diameter and the average thickness of the pressed tablets are 10 mm and 4.0 mm,respectively.In order to make low resistance electric contacts,the two sides of the pressed tablet are covered by silver pastes.The direct current resistance of the pressure sensor decreases by 3.3 times as the pressure increases up to 37 kN/m2.The simulation result of the resistance-pressure relationship is in good agreement with the experimental result within a variation of ±2%.

  5. Microstructure of Steel Fiber Reinforced Polymer-cement-based Composites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Mercury intrusion porosimetry was used to measure the pore structure of steel fiber reinforced polymer-cement-based composite.The results indicate that the large pore volume decreases by 57.8%-51.2% and by 87.1%-88% with the addition of steel fibers and polymers respectively.When both steel fibers and polymers are simultaneously added,the large pore volume decreases by 88.3%-90.1%.As a surface active material,polymer has a favorable water-reduced and forming-film effect,which is contributed to the decrease of the thickness of water film and the improvement of the conglutination between the fibers and the matrix.Polymers could form a microstructure network.This network structure and the bone structure of cement hydration products penetrate each other and thus the interpenetrating network with sticky aggregate and steel fiber inside forms.

  6. Mechanical properties of green composites based on thermoplastic starch

    Science.gov (United States)

    Fornes, F.; Sánchez-Nácher, L.; Fenollar, O.; Boronat, T.; Garcia-Sanoguera, D.

    2010-06-01

    The present work is focused on study of "green composites" elaborated from thermoplastic starch (TPS) as polymer matrix and a fiber from natural origin (rush) as reinforced fiber. The effect of the fiber content has been studied by means of the mechanical properties. The composite resulting presents a lack of interaction between matrix and fiber that represents a performance decrease. However the biodegradability behavior of the resulting composite raise this composite as useful an industrial level.

  7. Bio-based composites that mimic the plant cell wall

    OpenAIRE

    Li, Zhuo

    2009-01-01

    Nature creates high performance materials under modest conditions, i.e., neutral pH and ambient temperature and pressure. One of the most significant materials is the plant cell wall. The plant cell wall is a composite of oriented cellulose microfibrils reinforcing a lignin/hemicellulose matrix. In principle, the plant cell wall composite is designed much like a synthetic fiber-reinforced polymer composite. Unlike synthetic composites, the plant cell wall has an excellent combination of h...

  8. On the toughness enhancement in hydroxyapatite-based composites

    International Nuclear Information System (INIS)

    Among various biologically compatible materials, hydroxyapatite (HA) has excellent bioactivity/osteointegration properties and therefore has been extensively investigated for biomedical applications. However, its inferior fracture toughness limits the wider applications of monolithic HA as a load-bearing implant. To this end, HA-based biocomposites have been developed to improve their mechanical properties (toughness and strength) without compromising biocompatibility. Despite significant efforts over last few decades, the toughness of HA-based composites could not be enhanced beyond 1.5–2 MPa m1/2, even when measured using indentation techniques. In this perspective, the present work demonstrates how spark plasma sintering can be effectively utilized to develop hydroxyapatite–titanium (HA–Ti) composites with varying amounts of Ti (5, 10 and 20 wt.%) with extremely high single edge V-notch beam fracture toughness (4–5 MPa m1/2) along with a good combination of elastic modulus and flexural strength. Despite predominant retention of HA and Ti, the combination of critical analysis of X-ray diffraction and transmission electron microscopy investigation confirmed the formation of the CaTi4(PO4)6 phase with nanoscale morphology at the HA/Ti interface and the formation of such a phase has been discussed in reference to possible sintering reactions. The variations in the measured fracture toughness and work of fracture with Ti addition to the HA matrix were further rationalized using the analytical models of crack bridging as well as on the basis of the additional contribution from crack deflection. The present work opens up the opportunity to further enhance the toughness beyond 5 MPa m1/2 by microstructural designing with the desired combination of toughening phases

  9. Worldwide flight and ground-based exposure of composite materials

    Science.gov (United States)

    Dexter, H. B.; Baker, D. J.

    1984-01-01

    The long-term durability of those advanced composite materials which are applicable to aircraft structures was discussed. The composite components of various military and commercial aircraft and helicopters were reviewed. Both ground exposure and flight service were assessed in terms of their impact upon composite structure durability. The ACEE Program is mentioned briefly.

  10. Dissecting plasmodesmata molecular composition by mass spectrometry-based proteomics.

    Directory of Open Access Journals (Sweden)

    Emmanuelle Maria Françoise Bayer

    2013-01-01

    Full Text Available In plants, the intercellular communication through the membranous channels called plasmodesmata (PD; singular plasmodesma plays pivotal roles in the orchestration of development, defence responses and viral propagation. PD are dynamic structures embedded in the plant cell wall that are defined by specialised domains of the endoplasmic reticulum and the plasma membrane. PD structure and unique functions are guaranteed by their particular molecular composition. Yet, up to recent years and despite numerous approaches such as mutant screens, immunolocalisation or screening of random cDNAs, only few PD proteins had been conclusively identified and characterised. A clear breakthrough in the search of PD constituents came from mass-spectrometry-based proteomic approaches coupled with subcellular fractionation strategies. Due to their position, firmly anchored in the extracellular matrix, PD are notoriously difficult to isolate for biochemical analysis. Proteomic-based approaches have therefore first relied on the use of cell wall fractions containing embedded PD then on free PD fractions whereby PD membranes were released from the walls by enzymatic degradation. To discriminate between likely contaminants and PD protein candidates, bioinformatics tools have often been used in combination with proteomic approaches. GFP fusion proteins of selected candidates have confirmed the PD association of several protein families. Here we review the accomplishments and limitations of the proteomic based strategies to unravel the functional and structural complexity of PD. We also discuss the role of the identified PD associated proteins.

  11. Epoxy composites based on inexpensive tire waste filler

    Energy Technology Data Exchange (ETDEWEB)

    Ahmetli, Gulnare, E-mail: ahmetli@selcuk.edu.tr; Gungor, Ahmet, E-mail: ahmetli@selcuk.edu.tr; Kocaman, Suheyla, E-mail: ahmetli@selcuk.edu.tr [Department of Chemical Engineering, Faculty of Engineering, Selcuk University, 42031 Konya (Turkey)

    2014-05-15

    Tire waste (TW) was recycled as raw material for the preparation of DGEBA-type epoxy composite materials. The effects of filler amount and epoxy type on the mechanical properties of the composites were investigated. Tensile strength and Young’s modulus of the composites with NPEL were generally higher than composites with NPEF. The appropriate mass level for TW in both type composites was found to be 20 wt%. The equilibrium water sorption of NPEL/TW and NPEF/TW composites for 14-day immersion was determined as 0.10 % and 0.21 %, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used for characterization of the composites.

  12. Agricultural residues based composites II-gypsum plaster-fiber composites

    International Nuclear Information System (INIS)

    It is planned to get rid of some agricultural wastes, which form major environmental problems, to be used for the production of some valuable economic composites with gypsum plaster for wide important applications. Bagasse, cotton stalks, rice straw or linen fibers were blended with gypsum plaster to form the composites. Effect of each of the fiber type, length, content, and modification on the physicomechanical properties of the resulted composites were followed after different hydration conditions. Moreover, some selected composites were further investigated for their microstructure and thermal insulation properties. Results indicated that addition of fibers decreased the bulk density and mechanical properties of the composites. Density of composites with long fibers is lower than those contain short varieties although the compressive strength (CS)gave the reverse trend. Density and mechanical properties decreased as the added fibers ratio was increased. Strength of all composites increased on ageing. Cotton stalks composites gave 23 % increase in CS on using 2 % of 1.25 mm fiber than neat plaster. 2 % fiber addition of 0.8 mm gave almost the same results as the neat. The results of composites with more than 2 % fiber addition were lower than the neat gypsum. The CS of gypsum with 2 % linen fibers (1.25 mm) was higher than that of neat gypsum plaster, whereas, at 4 % fiber addition the CS was nearly the same as neat gypsum pastes. The composites with higher linen fiber contents than 4 % showed lower CS than neat gypsum paste. The modulus of rupture (MOR) of rice straw or Bagasse composites with 1.25 mm were slightly higher than that of 0.8 mm fiber length, but lower than the neat gypsum. Heat treatment at 105 degree C for 24 hours of cotton stalks decreased their properties. Acetylation of rice straw for different acetylation contents decreased their density, unaffected the CS and improved the MOR of the composites. Addition of CMC to cotton stalks has no benefit

  13. A new silver based composite material for SPA water disinfection.

    Science.gov (United States)

    Tartanson, M A; Soussan, L; Rivallin, M; Chis, C; Penaranda, D; Lapergue, R; Calmels, P; Faur, C

    2014-10-15

    A new composite material based on alumina (Al2O3) modified by two surface nanocoatings - titanium dioxide (TiO2) and silver (Ag) - was studied for spa water disinfection. Regarding the most common microorganisms in bathing waters, two non-pathogenic bacteria Escherichia coli (Gram-negative) and Staphylococcus epidermidis (Gram positive) were selected as surrogates for bacterial contamination. The bactericidal properties of the Al2O3-TiO2-Ag material were demonstrated under various operating conditions encountered in spa water (temperature: 22-37 °C, presence of salt: CaCO3 or CaCl2, high oxygen content, etc.). Total removal of 10(8) CFU mL(-1) of bacteria was obtained in less than 10 min with 16 g L(-1) of material. Best results were observed for both conditions: a temperature of 37 °C and under aerobic condition; this latest favouring Reactive Oxygen Species (ROS) generation. The CaCO3 salt had no impact on the bactericidal activity of the composite material and CaCl2 considerably stabilized the silver desorption from the material surface thanks to the formation of AgCl precipitate. Preliminary tests of the Al2O3-TiO2-Ag bactericidal behaviour in a continuous water flow confirmed that 2 g L(-1) of material eliminated more than 90% of a 2.0 × 10(8) CFU mL(-1) bacterial mixture after one water treatment recycle and reached the disinfection standard recommended by EPA (coliform removal = 6 log) within 22 h.

  14. Analysis of Orthogonal Cutting of Aluminium-based Composites

    Directory of Open Access Journals (Sweden)

    P. Ravinder Reddy

    2002-10-01

    Full Text Available A turning test on aluminium-based metal-matrix composites (MMCs (aluminium-30% silicon carbide was performed with K-20 carbide tool material and wear patterns and the wear land growth rates were analysed to evaluate the wear characteristics and to classify the relationship between the physical (mechanical properties and the flank wear of cutting tools. The study was also extended to the machining aspects and the width of cuts on MMCs and the influence of various cutting parameters. The experiments were conducted to measure the temperature along the cutting tool edge using thermocouple at various cutting speeds, and depth of cuts, keeping the feed rate constant while turning with K-20 carbide cutting tool. The finite-element method was used to simulate the orthogonal cutting of aluminium-based MMCs. The heat generation at the chip-tool interface, frictional heat generation at the tool flank, and the heat generation at the work tool interface were calculated analytically and imposed as boundary conditions. The analysis of the steady-state heat transfer was carried out and the temperature distribution at cutting edge, shear zone, and interface regions have been reported.

  15. DNA-based nanoparticle composite materials for EMI shielding

    Science.gov (United States)

    Zang, De Yu; Grote, James

    2012-03-01

    Composite materials, such as polymer-matrix containing conductive fillers, are very attractive for shielding electromagnetic interference (EMI) due to their high shielding efficiency and seamlessness, processability, flexibility, light-weight and low-cost. Here, we report a development of novel, DNA-based EMI-shielding materials (DESM), consisting of DNA and metal nanoparticles. It has been shown that a thin DESM layer (typically ~30 - 50 μm) could block EMI radiations up to 60 dB effectively over an RF frequency range from KHz to tens GHz, exhibiting excellent EMI shielding efficiency. A wide selection of metal nanoparticle fillers for DESM has been tested for their performance in EMI shielding efficiency. Among them, silver and carbon-based nanoparticles have demonstrated the best performance and were selected for further investigation. The silver-doped DESM films could be also non-conductive while their EMI shielding efficiency is still well-preserved. The nonconductive DESM could have a great potential in the microelectronics industries for EMI shielding on electronic devices and circuit boards.

  16. DC conductivity of silicon nitride based carbon-ceramic composites

    Directory of Open Access Journals (Sweden)

    B. Fényi

    2007-12-01

    Full Text Available The silicon nitride ceramics are usually known as strongly refractory and enduring materials and have typical electrically insulating properties. If the reinforcing phase of ceramic composite (that is mainly put in the material to improve mechanical properties is a good electrical conductor, it is worth to investigate the composite in electrical aspect. In this work carbon nanotubes, black-carbon and graphite were added to the basic silicon nitride ceramic and the electrical conductivity of the prepared carbon-ceramic composites was determined. The conductivity of the ceramic composites with different type and concentration of the carbon additives was observed by applying four point DC resistance measurements. Insulator and conductor composites in a wide conductivity range can be produced depending on the type and quantity of the additives. The additive types as well as the sintering parameters have influence on the basic electrical properties of the conductor composites.

  17. Durable polymer-aerogel based superhydrophobic coatings: a composite material

    Energy Technology Data Exchange (ETDEWEB)

    Kissel, David J.; Brinker, Charles Jeffrey

    2016-02-02

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  18. Biodegradable composites based on L-polylactide and jute fibres

    DEFF Research Database (Denmark)

    Plackett, David; Løgstrup Andersen, T.; Batsberg Pedersen, W.;

    2003-01-01

    Biodegradable polymers can potentially be combined with plant fibres to produce biodegradable composite materials. In our research, a commercial L-polylactide was converted to film and then used in combination with jute fibre mats to generate composites by a film stacking technique. Composite...... tensile properties were determined and tensile specimen fracture surfaces were examined using environmental scanning electron microscopy. Degradation of the polylactide during the process was investigated using size exclusion chromatography. The tensile properties of composites produced at temperatures in...... the 180-220 degreesC range were significantly higher than those of polylactide alone. Composite samples failed in a brittle fashion under tensile load and showed little sign of fibre pull-out. Examination of composite fracture surfaces using electron microscopy showed voids occurring between the jute...

  19. Durable polymer-aerogel based superhydrophobic coatings, a composite material

    Science.gov (United States)

    Kissel, David J; Brinker, Charles Jeffrey

    2014-03-04

    Provided are polymer-aerogel composite coatings, devices and articles including polymer-aerogel composite coatings, and methods for preparing the polymer-aerogel composite. The exemplary article can include a surface, wherein the surface includes at least one region and a polymer-aerogel composite coating disposed over the at least one region, wherein the polymer-aerogel composite coating has a water contact angle of at least about 140.degree. and a contact angle hysteresis of less than about 1.degree.. The polymer-aerogel composite coating can include a polymer and an ultra high water content catalyzed polysilicate aerogel, the polysilicate aerogel including a three dimensional network of silica particles having surface functional groups derivatized with a silylating agent and a plurality of pores.

  20. Management of service composition based on self-controlled components

    OpenAIRE

    Aubonnet, Tatiana; Henrio, Ludovic; Kessal, Soumia; Kulankhina, Oleksandra; Lemoine, Frédéric; Madelaine, Eric; Ruz, Cristian; Simoni, Noëmie

    2015-01-01

    Cloud computing and Future Internet promise a new ecosystem where everything is "as a service", reachable and connectable anywhere and anytime, everyone succeeding to get a service composition that meets his needs. But do we have the structure and the appropriate properties to design the service components and do we have the means to manage, at run-time, the personalised compositions corresponding to Service Level Agreement? In this article we introduce an entity of service composition called...

  1. Synthesis of Dichloride-Diphenylacetonitrile Palladium and Metal-Polymer Composite Based on Uhmwpe

    Directory of Open Access Journals (Sweden)

    A. M. Nemeryuk

    2016-05-01

    Full Text Available New complex of Pd (II with phenylacetonitrile, suitable for use as a precursor of palladium nano particles in the composition of metal-based composite UHMWPE was obtained. The thermodynamic characteristics of metal-polymer composite, found the effect of nano particles of palladium in the crystallization processes in UHMWPE and other characteristics of the material.

  2. Graphene-Based Composites as Cathode Materials for Lithium Ion Batteries

    OpenAIRE

    Libao Chen; Ming Zhang; Weifeng Wei

    2013-01-01

    Owing to the superior mechanical, thermal, and electrical properties, graphene was a perfect candidate to improve the performance of lithium ion batteries. Herein, we review the recent advances in graphene-based composites and their application as cathode materials for lithium ion batteries. We focus on the synthesis methods of graphene-based composites and the superior electrochemical performance of graphene-based composites as cathode materials for lithium ion batteries.

  3. Graphene-Based Composites as Cathode Materials for Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Libao Chen

    2013-01-01

    Full Text Available Owing to the superior mechanical, thermal, and electrical properties, graphene was a perfect candidate to improve the performance of lithium ion batteries. Herein, we review the recent advances in graphene-based composites and their application as cathode materials for lithium ion batteries. We focus on the synthesis methods of graphene-based composites and the superior electrochemical performance of graphene-based composites as cathode materials for lithium ion batteries.

  4. Ablation Properties of the Carbon-Based Composites Used in Artificial Heat Source Under Fire Accident

    Institute of Scientific and Technical Information of China (English)

    TANG; Xian; HUANG; Jin-ming; ZHOU; Shao-jian; LUO; Zhi-fu

    2012-01-01

    <正>The ablation properties of the carbon-based composites used in artificial heat source under fire accident were investigated by the arc heater. In this work, we tested the carbon-based composites referring to Fig. 1. Their linear/mass ablation ratio and ablation morphologies were studied. The results showed that the carbon-based composites used in artificial heat source behaved well

  5. The electrical properties of schungite-containing compositions based on polypropylene and high-density polyethylene

    Science.gov (United States)

    Rozhkov, S. S.; Kedrina, N. F.; Timofeeva, V. A.; Chmutin, I. A.; Ryvkina, N. G.; Solov'eva, A. B.

    2007-11-01

    Variations in the dc and ac conductivities of schungite-containing compositions based on polypropylene-high-density polyethylene (PP-PE) blends were studied depending on the composition of the polymeric blend, the volume concentration of the filler, and the order of the introduction of the composition components during the preparation of compositions. It was shown that the conductivities of the compositions could depend on the order of the introduction of the components. The structure of initial and schungite-containing PP-PE blends of different compositions was studied by atomic-force microscopy. It was shown that the structure of the compositions depended on the composition of the initial PP-PE blends and the order of the introduction of the components into schungite-filled PP-PE compositions.

  6. Characterisation of Flax Fibres and Flax Fibre Composites. Being cellulose based sources of materials

    DEFF Research Database (Denmark)

    Aslan, Mustafa

    a growing interest among composite manufacturers for such low-cost and low-weight cellulosic fibre composites. In addition, wood and plant fibre based composites with thermoplastic polymeric matrices are recyclable, and they are cost attractive alternatives to oil based fibre reinforced polymer composites......Cellulosic fibres, like wood and plant fibres, have the potential for use as load-bearing constituents in composite materials due to their attractive properties such as high stiffness-to-weight ratio that makes cellulosic fibre composites ideal for many structural applications. There is thus...... that currently have the largest market share for composite applications. However, the most critical limitation in the use of cellulosic fibre composites for structural applications is the lack of well described fibre properties, in particular, the tensile strength. This is due to variations in fibre morphology...

  7. Effects of SiC amount on phase compositions and properties of Ti3SiC2-based composites

    Institute of Scientific and Technical Information of China (English)

    蔡艳芝; 殷小玮; 尹洪峰

    2015-01-01

    The phase compositions and properties of Ti3SiC2-based composites with SiC addition of 5%−30% in mass fraction fabricated by in-situ reaction and hot pressing sintering were studied. SiC addition effectively prevented TiC synthesis but facilitated SiC synthesis. The Ti3SiC2/TiC−SiC composite had better oxidation resistance when SiC added quantity reached 20% but poorer oxidation resistance with SiC addition under 15%than Ti3SiC2/TiC composite at higher temperatures. There were more than half of the original SiC and a few Ti3SiC2 remaining in Ti3SiC2/TiC−SiC with 20% SiC addition, but all constituents in Ti3Si2/TiC composite were oxidized after 12 h in air at 1500 °C. The oxidation scale thickness of TS30, 1505.78μm, was near a half of that of T, 2715μm, at 1500 °C for 20 h. Ti3SiC2/TiC composite had a flexural strength of 474 MPa, which was surpassed by Ti3SiC2/TiC−SiC composites when SiC added amount reached 15%. The strength reached the peak of 518 MPa at 20%SiC added amount.

  8. Condition-based prediction of time-dependent reliability in composites

    Data.gov (United States)

    National Aeronautics and Space Administration — This paper presents a reliability-based prediction methodology to obtain the remaining useful life of composite materials subjected to fatigue degradation....

  9. Conifer fibers as reinforcing materials for polypropylene-based composites

    DEFF Research Database (Denmark)

    Plackett, David; Chengzhi, Chuai; Almdal, Kristoffer;

    2001-01-01

    in improved processing, as well as improvements in the thermal and mechanical properties of the resultant composites compared with the composites filled with untreated conifer fibers. Moreover, MAPP grafting and MAPP treating displayed more obvious benefits than EPDM treating in terms of thermal properties...

  10. Bio-Based Nanocomposites: An Alternative to Traditional Composites

    Science.gov (United States)

    Tate, Jitendra S.; Akinola, Adekunle T.; Kabakov, Dmitri

    2009-01-01

    Polymer matrix composites (PMC), often referred to as fiber reinforced plastics (FRP), consist of fiber reinforcement (E-glass, S2-glass, aramid, carbon, or natural fibers) and polymer matrix/resin (polyester, vinyl ester, polyurethane, phenolic, and epoxies). Eglass/ polyester and E-glass/vinyl ester composites are extensively used in the marine,…

  11. A Fuzzy-Decision Based Approach for Composite Event Detection in Wireless Sensor Networks

    OpenAIRE

    Shukui Zhang; Hao Chen; Qiaoming Zhu; Juncheng Jia

    2014-01-01

    The event detection is one of the fundamental researches in wireless sensor networks (WSNs). Due to the consideration of various properties that reflect events status, the Composite event is more consistent with the objective world. Thus, the research of the Composite event becomes more realistic. In this paper, we analyze the characteristics of the Composite event; then we propose a criterion to determine the area of the Composite event and put forward a dominating set based network topology...

  12. Polymer-based composite with outstanding mechanically tunable refractive index

    Science.gov (United States)

    Mohamed-Noriega, Nasser; Hinojosa, Moisés; González, Virgilio; Rodil, Sandra. E.

    2016-08-01

    A composite with high visible light transmittance, mechanically tunable refractive index (RI) and rubber-like mechanical properties, based on poly(dimethylsiloxane) (PDMS) and barium titanate nanoparticles (BT) was prepared on three steps. First, BT nanoparticles were obtained by high-energy milling. Second, the nanoparticles were embedded in PDMS by in-situ polymerization; the BT content was varied up to 1.0 wt% (0.17 vol%). Finally, ∼0.5 mm membranes were prepared by solvent casting. The effect of the BT concentration was examined. Powder XRD and Raman spectroscopy revealed a tetragonal crystal structure for the nanoparticles. SEM images confirmed a mean particle size of ∼64 nm and together with EDX mappings showed a moderate dispersion of the nanoparticles in some membranes, whereas other exhibited agglomerates at the surface. The normal transmittance of the membranes was measured with a spectroscopic ellipsometer while they were stretched in-situ at different percentages. The RI variations as a function of strain were calculated from the transmittance spectra. The results exhibit surprising variations in the RI, up to ∼5 times higher than those associated to PDMS alone, implying that the presence of BT significantly influences the optical response of the PDMS when stretched. However, the response is neither linear nor well understood; further studies must be performed to clarify this new interaction.

  13. Base Composition Characteristics of Mammalian miRNAs

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2013-01-01

    Full Text Available MicroRNAs (miRNAs are short RNA sequences that repress protein synthesis by either inhibiting the translation of messenger RNA (mRNA or increasing mRNA degradation. Endogenous miRNAs have been found in various organisms, including animals, plants, and viruses. Mammalian miRNAs are evolutionarily conserved, are scattered throughout chromosomes, and play an important role in the immune response and the onset of cancer. For this study, the author explored the base composition characteristics of miRNA genes from the six mammalian species that contain the largest number of known miRNAs. It was found that mammalian miRNAs are evolutionarily conserved and GU-rich. Interestingly, in the miRNA sequences investigated, A residues are clearly the most frequent occupants of positions 2 and 3 of the 5′ end of miRNAs. Unlike G and U residues that may pair with C/U and A/G, respectively, A residues can only pair with U residues of target mRNAs, which may augment the recognition specificity of the 5′ seed region.

  14. Micromechanics Based Inelastic and Damage Modeling of Composites

    Directory of Open Access Journals (Sweden)

    P. P. Procházka

    2004-01-01

    Full Text Available Micromechanics based models are considered for application to viscoelasticity and damage in metal matrix composites. The method proposes a continuation and development of Dvooák’s transformation field analysis, considering the piecewise uniform eigenstrains in each material phase. Standard applications of the method to a two-phase are considered in this study model, i.e., only one sub-volume per phase is considered. A continuous model is used, employing transformation field analysis with softening in order to prevent the tensile stress overstepping the tensile strength. At the same time shear cracking occurs in the tangential direction of the possible crack. This is considered in the principal shear stresses and they make disconnections in displacements. In this case, discontinuous models are more promising. Because discrete models, that can describe the situation more realistically have not been worked out in detail, we retain a continuous model and substitute the slip caused by overstepping the damage law by introducing eigenparameters from TFA. The various aspects of the proposed methods are systematically checked by comparing with finite element unit cell analyses, made through periodic homogenization assumptions, for SiC/Ti unidirectional lay-ups. 

  15. Polymer-based tubular microbots: role of composition and preparation

    Science.gov (United States)

    Gao, Wei; Sattayasamitsathit, Sirilak; Uygun, Aysegul; Pei, Allen; Ponedal, Adam; Wang, Joseph

    2012-03-01

    The influence of the composition and electropolymerization conditions upon the propulsion of new template-prepared polymer-based bilayer microtubular microbots is described. The effects of different electropolymerized outer layers, including polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) (PEDOT), polyaniline (PANI), and of various inner catalytic metal surfaces (Ag, Pt, Au, Ni-Pt alloy), upon the movement of such bilayer microtubes are evaluated and compared. Electropolymerization conditions, such as the monomer concentration and medium (e.g. surfactant, electrolyte), have a profound effect upon the morphology and locomotion of the resulting microtubes. The most efficient propulsion is observed using PEDOT/Pt microbots that offer a record-breaking speed of over 1400 body lengths s-1 at physiological temperature, which is the fastest relative speed reported to date for all artificial micro/nanomotors. An inner Pt-Ni alloy surface is shown useful for combining magnetic control and catalytic fuel decomposition within one layer, thus greatly simplifying the preparation of magnetically-guided microbots. Polymer-based microbots with an inner gold layer offer efficient biocatalytic propulsion in low peroxide level in connection to an immobilized catalase enzyme. Metallic Au/Pt bilayer microbots can also be prepared electrochemically to offer high speed propulsion towards potential biomedical applications through functionalization of the outer gold surface. Such rational template preparation and systematic optimization of highly efficient microbots hold considerable promise for diverse practical applications.The influence of the composition and electropolymerization conditions upon the propulsion of new template-prepared polymer-based bilayer microtubular microbots is described. The effects of different electropolymerized outer layers, including polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) (PEDOT), polyaniline (PANI), and of various inner catalytic metal

  16. Thermal Conductivity behavior of MWCNT based PMMA and PC composites

    Science.gov (United States)

    Dubey, Girija; Jindal, Prashant; Bhandari, Rajiv; Dhiman, Neha; Bajaj, Chetan; Jindal, Vijay

    Poly methyl methacrylate (PMMA) and Polycarbonate (PC) are low cost polymer materials which can be easily transformed into desired shapes for various applications. However they have poor mechanical, thermal and electrical properties which are required to be enhanced to widen their scope of applications specifically where along with high strength, rapid heat transfer is essential. Multi Walled Carbon nanotubes (MWCNTs) are excellent new materials having extraordinary mechanical and transport properties. We will report results of fabricating composites of varying compositions of MWCNTs with PMMA and PC and their thermal conductivity behaviour using simple transient heat flow methods. The samples in disk shapes of around 2 cm diameters and 0.2 cm thickness with MWCNT compositions varying up to 10 wt% were fabricated. We found that both PMMA and PC measured high thermal conductivity with increase in the composition of CNTs. The thermal conductivity of 10wt% MWCNT/PMMA composite increased by nearly two times in comparison to pure PMMA.

  17. Study on Microstructure of Alumina Based Rare Earth Ceramic Composite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Analysis techniques such as SEM, TEM and EDAX were used to investigate the microstructure of rare earth reinforced Al2O3/(W, Ti)C ceramic composite. Chemical and physical compatibility of the composite was analyzed and interfacial microstructure was studied in detail. It is found that both Al2O3 and (W, Ti)C phases are interlaced with each other to form the skeleton structure in the composite. A small amount of pores and glass phases are observed inside the material which will inevitably influence the physical and mechanical property of the composite. Thermal residual stresses resulted from thermal expansion mismatch can then lead to the emergence of dislocations and microcracks. Interfaces and boundaries of different types are found to exist inside the Al2O3/(W, Ti)C rare earth ceramic composite, which is concerned with the addition of rare earth element and the extent of solid solution of ceramic phases.

  18. Mechanical and thermal properties of sisal fiber-reinforced rubber seed oil-based polyurethane composites

    International Nuclear Information System (INIS)

    The development of high-performance composite materials from locally sourced and renewable materials was investigated. Rubber seed oil polyurethane resin synthesized using rubber seed monoglyceride derived from glycerolysis of the oil was used as matrix in the composite samples. Rubber seed oil-based polyurethane composite reinforced with unidirectional sisal fibers were prepared and characterized. Results showed that the properties of unidirectional fiber-reinforced rubber seed oil-based polyurethane composites gave good thermal and mechanical properties. Also, the values of tensile strengths and flexural moduli of the polyurethane composites were more than tenfold and about twofold higher than un-reinforced rubber seed oil-based polyurethane. The improved thermal stability and the scanning electron micrographs of the fracture surface of the composites were attributed to good fiber-matrix interaction. These results indicate that high-performance 'all natural products' composite materials can be developed from resources that are readily available locally.

  19. Nanomechanics of cellulose crystals and cellulose-based polymer composites

    Science.gov (United States)

    Pakzad, Anahita

    Cellulose-polymer composites have potential applications in aerospace and transportation areas where lightweight materials with high mechanical properties are needed. In addition, these economical and biodegradable composites have been shown to be useful as polymer electrolytes, packaging structures, optoelectronic devices, and medical implants such as wound dressing and bone scaffolds. In spite of the above mentioned advantages and potential applications, due to the difficulties associated with synthesis and processing techniques, application of cellulose crystals (micro and nano sized) for preparation of new composite systems is limited. Cellulose is hydrophilic and polar as opposed to most of common thermoplastics, which are non-polar. This results in complications in addition of cellulose crystals to polymer matrices, and as a result in achieving sufficient dispersion levels, which directly affects the mechanical properties of the composites. As in other composite materials, the properties of cellulose-polymer composites depend on the volume fraction and the properties of individual phases (the reinforcement and the polymer matrix), the dispersion quality of the reinforcement through the matrix and the interaction between CNCs themselves and CNC and the matrix (interphase). In order to develop economical cellulose-polymer composites with superior qualities, the properties of individual cellulose crystals, as well as the effect of dispersion of reinforcements and the interphase on the properties of the final composites should be understood. In this research, the mechanical properties of CNC polymer composites were characterized at the macro and nano scales. A direct correlation was made between: - Dispersion quality and macro-mechanical properties - Nanomechanical properties at the surface and tensile properties - CNC diameter and interphase thickness. Lastly, individual CNCs from different sources were characterized and for the first time size-scale effect on

  20. Dynamic web service composition based on OWL-S

    Institute of Scientific and Technical Information of China (English)

    Jing DONG; Yongtao SUN; Sheng YANG; Kang ZHANG

    2006-01-01

    Composing existing web services for enterprise applications may enable higher level of reuse. However the composition processes are mostly static and lack of support for runtime redesign. In this paper, we describe our approach to the extension of the OWL-S ontology framework for dynamic web service composition. We raise the level of abstraction and propose an abstract service layer so that web services can be composed at the abstract service level instead of the concrete level. Each abstract service is attached with an instance pool including all instances of the abstract service to facilitate fail-over and dynamic compositions.

  1. Composite separators and redox flow batteries based on porous separators

    Science.gov (United States)

    Li, Bin; Wei, Xiaoliang; Luo, Qingtao; Nie, Zimin; Wang, Wei; Sprenkle, Vincent L.

    2016-01-12

    Composite separators having a porous structure and including acid-stable, hydrophilic, inorganic particles enmeshed in a substantially fully fluorinated polyolefin matrix can be utilized in a number of applications. The inorganic particles can provide hydrophilic characteristics. The pores of the separator result in good selectivity and electrical conductivity. The fluorinated polymeric backbone can result in high chemical stability. Accordingly, one application of the composite separators is in redox flow batteries as low cost membranes. In such applications, the composite separator can also enable additional property-enhancing features compared to ion-exchange membranes. For example, simple capacity control can be achieved through hydraulic pressure by balancing the volumes of electrolyte on each side of the separator. While a porous separator can also allow for volume and pressure regulation, in RFBs that utilize corrosive and/or oxidizing compounds, the composite separators described herein are preferable for their robustness in the presence of such compounds.

  2. Optimization of compressive strength of zirconia based dental composites

    Indian Academy of Sciences (India)

    U V Hambire; V K Tripathi

    2014-10-01

    Dental composites are tooth-coloured restorative material used by dentists for various applications. Restoration of a lost tooth structure requires a material having mechanical as well as aesthetic properties similar to that of tooth. This poses challenges to engineers and the dentist alike. Dental composites consist of a matrix and a dispersed phase called filler, which are mainly responsible for its mechanical properties. Most commonly used matrix is bisphenol glycidyl methacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGMA). Silica and glass are conventional fillers used in the past. Recently, zirconia is being used due to its improved mechanical properties. A study was conducted to evaluate the contribution of zirconia to the mechanical properties in general and compressive strength in particular. We have attempted to make an experimental dental composite with a conglomerate of nanofillers, namely, zirconia, glass and silica, and optimize this filler volume percentage and obtain an optimum compressive strength for the experimental dental composite.

  3. Novel, Nanotechnology Based CMC composites for Hot Structures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Very extensive R&D efforts over the past several decades resulted in several classes of high temperature composites offering potential for future hypersonic...

  4. The Aluminum Based Composite Produced by Self Propagating High Temperature Synthesis

    Directory of Open Access Journals (Sweden)

    Agus PRAMONO

    2016-05-01

    Full Text Available Self-propagating high-temperature synthesis method can be used for producing aluminum and boron carbide based composites. The experimental composites were fabricated using cobalt and carbon as catalysts. The microstructure of the material was studied using Scanning Electron Microscopy and the mechanical properties were determined using micro-hardness testing. Al/B4C based composites with improved properties were obtained and the role of Co/C catalysts was studied.

  5. Structure Design of the 3-D Braided Composite Based on a Hybrid Optimization Algorithm

    Science.gov (United States)

    Zhang, Ke

    Three-dimensional braided composite has the better designable characteristic. Whereas wide application of hollow-rectangular-section three-dimensional braided composite in engineering, optimization design of the three-dimensional braided composite made by 4-step method were introduced. Firstly, the stiffness and damping characteristic analysis of the composite is presented. Then, the mathematical models for structure design of the three-dimensional braided composite were established. The objective functions are based on the specific damping capacity and stiffness of the composite. The design variables are the braiding parameters of the composites and sectional geometrical size of the composite. The optimization problem is solved by using ant colony optimization (ACO), contenting the determinate restriction. The results of numeral examples show that the better damping and stiffness characteristic could be obtained. The method proposed here is useful for the structure design of the kind of member and its engineering application.

  6. A new type of bentonite-based non-woven composite

    Directory of Open Access Journals (Sweden)

    Rosić Branko

    2011-01-01

    Full Text Available Sandwich-like composites based on clays and textiles are extensively applied in various fields, including civil engineering and environmental protection. In this paper, the synthesis of a new type of composite with embedded bentonite particles within a non-woven polyester matrix is presented. The synthesized composite has improved mechanical properties compared to the corresponding non-woven matrix. Although more than two-times thinner, the synthesized composite showed mechanical properties similar to those of a commercial composite chosen for comparison. Sorption test results confirmed that the contribution of the textile component to the sorption of aqueous Cu(II ions by the composite was negligible. The sorption of aqueous Cu(II ions on the synthesized composite was best-fitted using the Langmuir model. The presented study confirmed that the loss of bentonite particles from the composite can be eliminated using the suggested synthesis method.

  7. Fabrication of Biosensor Based on Polyaniline/Gold Nanorod Composite

    OpenAIRE

    Uğur Tamer; Ali İhsan Seçkin; Erhan Temur; Hilal Torul

    2011-01-01

    This present paper describes a new approach to fabricate a new amperometric sensor for the determination of glucose. Polyaniline (PANI) film doped with colloidal gold nanorod particles has been used to immobilize glucose oxidase by glutaraldehyde. The polyaniline/gold nanorod composite structure gave an excellent matrix for enzyme immobilization due to the large specific surface area and higher electroactivity. The composite has been characterized by cyclic voltammetry (CV), scanning electron...

  8. Polyaniline and mineral clay-based conductive composites

    OpenAIRE

    Samantha Oliveira Vilela; Mauro Alfredo Soto-Oviedo; Ana Paula Fonseca Albers; Roselena Faez

    2007-01-01

    Composite materials have attracted the attention of numerous researchers due to the distinct properties shown by this class of materials and the mineral clay used in their synthesis. In this study, conductive composites were obtained by mixing polyaniline (PAni) with clay (kaolinite and montmorillonite). The aniline was polymerized in a medium with clay and the powder was characterized by X ray diffraction, electrical conductivity and morphology. The results suggest PAni chain linearization i...

  9. A fault and seismicity based composite simulation in northern California

    Directory of Open Access Journals (Sweden)

    M. B. Yıkılmaz

    2011-12-01

    Full Text Available We generate synthetic catalogs of seismicity in northern California using a composite simulation. The basis of the simulation is the fault based "Virtual California" (VC earthquake simulator. Back-slip velocities and mean recurrence intervals are specified on model strike-slip faults. A catalog of characteristic earthquakes is generated for a period of 100 000 yr. These earthquakes are predominantly in the range M = 6 to M = 8, but do not follow Gutenberg-Richter (GR scaling at lower magnitudes. In order to model seismicity on unmapped faults we introduce background seismicity which occurs randomly in time with GR scaling and is spatially associated with the VC model faults. These earthquakes fill in the GR scaling down to M = 4 (the smallest earthquakes modeled. The rate of background seismicity is constrained by the observed rate of occurrence of M > 4 earthquakes in northern California. These earthquakes are then used to drive the BASS (branching aftershock sequence model of aftershock occurrence. The BASS model is the self-similar limit of the ETAS (epidemic type aftershock sequence model. Families of aftershocks are generated following each Virtual California and background main shock. In the simulations the rate of occurrence of aftershocks is essentially equal to the rate of occurrence of main shocks in the magnitude range 4 < M < 7. We generate frequency-magnitude and recurrence interval statistics both regionally and fault specific. We compare our modeled rates of seismicity and spatial variability with observations.

  10. Silicon tetrachloride plasma induced grafting for starch-based composites

    Science.gov (United States)

    Ma, Yonghui C.

    Non-modified virgin starch is seldom used directly in industrial applications. Instead, it is often physically and/or chemically modified to achieve certain enhanced properties. For many of the non-food applications, these modifications involve changing its hydrophilicity to create hydrophobic starch. In this study, the hydrophobic starch was produced through silicon tetrachloride (SiCl4) plasma induced graft polymerization, so that it could be used as a renewable and biodegradable component of, or substitute for, the petrochemical-based plastics. It was suggested that this starch graft-copolymer might be used as reinforcing components in silicone-rubber materials for starch-based composites. To make this starch graft-copolymer, the ethyl ether-extracted starch powders were surface functionalized by SiCl4 plasma using a 13.56 MHz radio frequency rotating plasma reactor and subsequently stabilized by either ethylene diamine or dichlorodimethylsilane (DCDMS). The functionalized starch was then graft-polymerized with DCDMS to form polydimethylsiloxane (PDMS) layers around the starch granules. The presence of this PDMS layer was demonstrated by electron spectroscopy for chemical analysis (ESCA/XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), gas chromatography-mass spectroscopy (GC-MS), thermo gravimetry/differential thermal analysis (TG/DTA), and other analyses. It was shown that the surface morphology, thermal properties, swelling characteristic, and hydrophilicity of starch were all changed due to the existence of this protective hydrophobic PDMS layer. Several different procedures to carry out the functionalization and graft polymerization steps were evaluated to improve the effectiveness of the reactions and to prevent the samples from being hydrolyzed by the grafting byproduct HCl. Actinometry, GC-MS, and residual gas analyzer (RGA) were used to investigate the mechanisms of the SiCl4 discharge and to optimize the plasma

  11. Shrinkage kinetics of a methacrylate- and a silorane-based resin composite: effect on marginal integrity

    NARCIS (Netherlands)

    L. Gregor; T. Bortolotto; A.J. Feilzer; I. Krejci

    2013-01-01

    Purpose: To evaluate the relation between the linear displacement (LD), shrinkage force (SF) and marginal adaptation of a methacrylate- and a silorane-based composite. Materials and Methods: The LD and SF of 8 samples made of Filtek Supreme XT (methacrylate-based composite) and Filtek Silorane (silo

  12. Fracture strength and fatigue resistance of dental resin-based composites

    NARCIS (Netherlands)

    F. Keulemans; P. Palav; M.M.N. Aboushelib; A. van Dalen; C.J. Kleverlaan; A.J. Feilzer

    2009-01-01

    Objectives: The aim of this study was to evaluate in vitro the influence of fiber-reinforcement on the fracture strength and fatigue resistance of resin-based composites. Methods: One hundred rectangular bar-shaped specimens (2 mm × 2 mm × 25 mm) made of resin-based composite were prepared in a stai

  13. Recent advances in noble metal based composite nanocatalysts: colloidal synthesis, properties, and catalytic applications

    Science.gov (United States)

    Xu, Yong; Chen, Lei; Wang, Xuchun; Yao, Weitang; Zhang, Qiao

    2015-06-01

    This Review article provides a report on progress in the synthesis, properties and catalytic applications of noble metal based composite nanomaterials. We begin with a brief discussion on the categories of various composite materials. We then present some important colloidal synthetic approaches to the composite nanostructures; here, major attention has been paid to bimetallic nanoparticles. We also introduce some important physiochemical properties that are beneficial from composite nanomaterials. Finally, we highlight the catalytic applications of such composite nanoparticles and conclude with remarks on prospective future directions.

  14. Fabrication and characterization of LATP/PAN composite fiber-based lithium-ion battery separators

    Energy Technology Data Exchange (ETDEWEB)

    Liang Yinzheng [Department of Textile Materials Science and Product Design, College of Textile, Donghua University, Shanghai 201620 (China); Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, NC 27695-8301 (United States); Lin Zhan [Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, NC 27695-8301 (United States); Qiu Yiping [Department of Textile Materials Science and Product Design, College of Textile, Donghua University, Shanghai 201620 (China); Zhang Xiangwu, E-mail: xiangwu_zhang@ncsu.edu [Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, NC 27695-8301 (United States)

    2011-07-15

    Lithium aluminum titanium phosphate (LATP)/polyacrylonitrile (PAN) composite fiber-based membranes were prepared by electrospinning dispersions of LATP particles in PAN solutions. The electrolyte uptakes of the electrospun LATP/PAN composite fiber-based membranes were measured and the results showed that the electrolyte uptake increased as the LATP content increased. The lithium ion conductivity, the electrochemical oxidation limit and the interface resistance of liquid electrolyte-soaked electrospun LATP/PAN composite fiber-based membranes were also measured and it was found that as the LATP content increased, the electrospun LATP/PAN composite fiber-based membranes had higher lithium ion conductivity, better electrochemical stability, and lower interfacial resistance with lithium electrode. Additionally, lithium//1 M LiPF{sub 6}/EC/EMC//lithium iron phosphate cells using LATP/PAN composite fiber-based membranes as the separator demonstrated high charge/discharge capacity and good cycle performance.

  15. Epoxy Resin Composite Based on Functional Hybrid Fillers

    Directory of Open Access Journals (Sweden)

    Mariusz Oleksy

    2014-08-01

    Full Text Available A study was carried out involving the filling of epoxy resin (EP with bentonites and silica modified with polyhedral oligomeric silsesquioxane (POSS. The method of homogenization and the type of filler affect the functional and canceling properties of the composites was determined. The filler content ranged from 1.5% to 4.5% by mass. The basic mechanical properties of the hybrid composites were found to improve, and, in particular, there was an increase in tensile strength by 44%, and in Charpy impact strength by 93%. The developed hybrid composites had characteristics typical of polymer nanocomposites modified by clays, with a fine plate morphology of brittle fractures observed by SEM, absence of a plate separation peak in Wide Angles X-ray Scattering (WAXS curves, and an exfoliated structure observed by TEM.

  16. Agricultural Residues Based Composites 1. Preparation of Fibrous Agricultural Residues

    International Nuclear Information System (INIS)

    The aim of this study is to use agricultural residues as bagasse, cotton stalks, rice straw, linen and linen fibers, which are produced in Egypt in huge amounts annually to produce composites with cement or gypsum. Also the effect of physical and chemical treatments of the fibers and the addition of some additives to the composites was studied. The mechanical properties of the produced composites also the effect of its firing at temperatures up to 800 degree C was tested after dipping in water for different time intervals (1-90 days). In this paper we considered only the preparation of different types of fibers, its grinding and separation to different fiber lengths (ca. 0.4 to 1.5 mm). The percent of each fiber length and its chemical and physical analysis is found

  17. Electrical Response of Cement-Based Piezoelectric Ceramic Composites under Mechanical Loadings

    Directory of Open Access Journals (Sweden)

    Biqin Dong

    2011-01-01

    Full Text Available Electrical responses of cement-based piezoelectric ceramic composites under mechanical loadings are studied. A simple high order model is presented to explain the nonlinear phenomena, which is found in the electrical response of the composites under large mechanical loadings. For general situation, this nonlinear piezoelectric effect is quite small, and the composite is suitable for dynamic mechanical sensor as holding high static stability. The experimental results are consistent with the relationship quite well. The study shows that cement-based piezoelectric composite is suitable for potential application as dynamic mechanical sensor with excellent dynamic response and high static stability.

  18. Properties of new fully bio-based thermoset composites

    DEFF Research Database (Denmark)

    Bierer, M.; Pohl, T.; Natter, E.;

    2010-01-01

    In the present study, natural fibre textiles had been impregnated with the furan resin to form pre-pregs. The pre-pregs were consolidated into composites in a compression mould and the mechanical properties, the burning behaviour and the moisture sorption behaviour had been determined.......In the present study, natural fibre textiles had been impregnated with the furan resin to form pre-pregs. The pre-pregs were consolidated into composites in a compression mould and the mechanical properties, the burning behaviour and the moisture sorption behaviour had been determined....

  19. Effects of Fiber-reinforced Composite Bases on Microleakage of Composite Restorations in Proximal Locations

    Science.gov (United States)

    A, Tezvergil-Mutluay; P.K, Vallittu

    2014-01-01

    Objectives: The aim of this study was to evaluate the microleakage of direct restorative composite resin upon the addition of an intermediate glass fiber-reinforced composite (GFRC) layer of various fiber orientations between tooth and particulate filler composite resin (PFRC). Materials and Methods: Cavities were prepared both on the mesial and distal surfaces of sixty extracted human molars with one margin placed below and the other above the cementoenamel junction (CEJ). Teeth were assigned to five different groups. Four of the groups received a layer of semi-interpenetrating polymer network (semi-IPN) resin system impregnated E-glass GFRC at the bottom of the cavity: Group 1; unidirectional continuous GFRC (EVS) in buccolingual direction (EVS-BL), Group 2; EVS in mesiodistal direction (EVS-MD), Group 3; bidirectional woven GFRC (EVN), Group 4; multidirectional short GFRC (EXP-MLT), Group 5; PRFC only (control). After acid etching and priming of the cavities and insertion of GFRC layer with the adhesive resin (Scotchbond Multipurpose 3M-ESPE), the cavities were filled incrementally with PRFC (Filtek Z250, 3M-ESPE) and each layer was light cured for 20 s. After finishing and polishing, the restored teeth were water-stored for 24 h at 37 °C and then thermocycled for 6000 cycles between 5-55 °C, before immersion in 0.5 % basic fuchsin dye for 24 h. After sectioning by 3-5 sagittal cuts, each sequential section was imaged and digitally analyzed to determine the stain depth. Results: All GFRC groups in dentin revealed significantly lower microleakage compared to control (p0.05). The microleakeage in enamel was not different between the groups (p>0.05). Conclusion: Use of intermediate GFRC layer between tooth and PFRC could provide alternative method to minimize microleakage. Clinical Relevance: Use of GFRC intermediate layer underneath the particulate filler composite can be used to minimize the leakeage of the restorations. PMID:25512764

  20. Compositional design and microstructure analysis of Zr-based bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The systematical studies of Zr-based BMGs were summarized in terms of their compositional design and their structural characterization. In particular, several key issues of BMG materials were focused, including initial alloy design and subsequent composition optimization, solidification microstructure characterization and crystallization process specification. The results show that a compositional designing approach is successfully developed and, through extensive microstructure characterization using transmission electron microscopy, several new crystalline phases are discovered in these newly developed Zr-based BMG alloys.Crystallization behavior of Zr-based BMG is also determined based on the microstructure analysis.

  1. Prediction of anisotropic behavior of nano/micro composite based on damage mechanics with cell modeling.

    Science.gov (United States)

    Lee, Dock-Jin; Kim, Young-Jin; Kim, Moon-Ki; Choi, Jae-Boong; Chang, Yoon-Suk; Liu, Wing Kam

    2011-01-01

    New advanced composite materials have recently been of great interest. Especially, many researchers have studied on nano/micro composites based on matrix filled with nano-particles, nano-tubes, nano-wires and so forth, which have outstanding characteristics on thermal, electrical, optical, chemical and mechanical properties. Therefore, the need of numerical approach for design and development of the advanced materials has been recognized. In this paper, finite element analysis based on multi-resolution continuum theory is carried out to predict the anisotropic behavior of nano/micro composites based on damage mechanics with a cell modeling. The cell modeling systematically evaluates constitutive relationships from microstructure of the composite material. Effects of plastic anisotropy on deformation behavior and damage evolution of nano/micro composite are investigated by using Hill's 48 yield function and also compared with those obtained from Gurson-Tvergaard-Needleman isotropic damage model based on von Mises yield function.

  2. Hierarchical Scheduling Framework Based on Compositional Analysis Using Uppaal

    DEFF Research Database (Denmark)

    Boudjadar, Jalil; David, Alexandre; Kim, Jin Hyun;

    2014-01-01

    This paper introduces a reconfigurable compositional scheduling framework, in which the hierarchical structure, the scheduling policies, the concrete task behavior and the shared resources can all be reconfigured. The behavior of each periodic preemptive task is given as a list of timed actions, ...

  3. Enhanced Dielectric Constant for Efficient Electromagnetic Shielding Based on Carbon-Nanotube-Added Styrene Acrylic Emulsion Based Composite

    OpenAIRE

    Chen Changxin; Zhang Song; Ni Yuwei; Cai Seng; Huang Jie; Li Yong; Li Jiang-Tao

    2010-01-01

    Abstract An efficient electromagnetic shielding composite based on multiwalled carbon nanotubes (MWCNTs)-filled styrene acrylic emulsion-based polymer has been prepared in a water-based system. The MWCNTs were demonstrated to have an effect on the dielectric constants, which effectively enhance electromagnetic shielding efficiency (SE) of the composites. A low conductivity threshold of 0.23 wt% can be obtained. An EMI SE of ~28 dB was achieved for 20 wt% MWCNTs. The AC conductivity (σ ac...

  4. Hygroscopicity -resistant mechanism of an α -starch based composite binder for dry sand molds and cores

    Directory of Open Access Journals (Sweden)

    Xia ZHOU

    2005-05-01

    Full Text Available Hygroscopicity-resistance of an α-starch based composite binder for dry sand molds (cores has been studied experimentally and theoretically. Focus is placed on the relationship between the hardening structure and humidity-resistance of the composite binder. The results show that the α-starch composite binder has good humidity-resistance due to its special complex structure. SEM observations illustrate that the composite binder consists of reticular matrix and a ball- or lump-shaped reinforcement phase, and the specific property of the binding membrane with heterogeneous structure is affected by humidity to a small extent. Based on the analyses on the interplays of different ingredients in the binder at hardening, the structure model and hygroscopicity-resistant mechanisms of the hardening composite binder were further proposed. Moreover, the reasons for good humidity-resistance of the composite binder bonded sand are well explained by the humidity-resistant mechanisms.

  5. On the elastic properties of carbon nanotube-based composites: modelling and characterization

    CERN Document Server

    Thostenson, E T

    2003-01-01

    The exceptional mechanical and physical properties observed for carbon nanotubes has stimulated the development of nanotube-based composite materials, but critical challenges exist before we can exploit these extraordinary nanoscale properties in a macroscopic composite. At the nanoscale, the structure of the carbon nanotube strongly influences the overall properties of the composite. The focus of this research is to develop a fundamental understanding of the structure/size influence of carbon nanotubes on the elastic properties of nanotube-based composites. Towards this end, the nanoscale structure and elastic properties of a model composite system of aligned multi-walled carbon nanotubes embedded in a polystyrene matrix were characterized, and a micromechanical approach for modelling of short fibre composites was modified to account for the structure of the nanotube reinforcement to predict the elastic modulus of the nanocomposite as a function of the constituent properties, reinforcement geometry and nanot...

  6. Durability-Based Design Criteria for a Chopped-Glass-Fiber Automotive Structural Composite

    Energy Technology Data Exchange (ETDEWEB)

    Battiste, R.L.; Corum, J.M.; Ren, W.; Ruggles, M.B.

    1999-11-01

    This report provides recommended durability-based design criteria for a chopped-glass-fiber reinforced polymeric composite for automotive structural applications. The criteria closely follow the framework of an earlier criteria document for a continuous-strand-mat (CSM) glass-fiber reference composite. Together these design criteria demonstrate a framework that can be adapted for future random-glass-fiber composites for automotive structural applications.

  7. Durability-Based Design Criteria for a Chopped-Glass-Fiber Automotive Structural Composite; TOPICAL

    International Nuclear Information System (INIS)

    This report provides recommended durability-based design criteria for a chopped-glass-fiber reinforced polymeric composite for automotive structural applications. The criteria closely follow the framework of an earlier criteria document for a continuous-strand-mat (CSM) glass-fiber reference composite. Together these design criteria demonstrate a framework that can be adapted for future random-glass-fiber composites for automotive structural applications

  8. Thermal characterization of the composites based on poly(lactic acid)

    OpenAIRE

    Srebrenkoska, Vineta; Bogoeva-Gaceva, Gordana

    2011-01-01

    In this study, rice-hulls-filled poly (lactic acid) (PLA) composites were prepared through addition of 5 wt. % PLA-grafted-MA (CA) for enhancement of adhesion between polymer matrix and natural filler. The composites containing 30% wt. rice hulls (RH) were prepared by compression molding. For the composites, the thermal properties were analyzed and compared to those of commonly used thermoplastic based-polymer, polypropylene (PP) containing the same reinforcement. Thermal stability of composi...

  9. Design of electrically conducting polymer hybrid composites based on polyvinyl chloride and polyethylene

    OpenAIRE

    Kuryptya, Yaroslav; Sova, Nadiya; Savchenko, Bohdan; Slieptsov, Aleksander; Plavan, Viktoriia

    2016-01-01

    Interest to electrically conducting polymer composite materials in recent times has grown considerably, which is associated with the design of new branches of science and technology. The existing analogues are different in the complexity of production and high cost. One of the ways of solving the problem may be designing polymer composite materials with a combined filler. The research was carried out on creating electrically conducting hybrid polymer composites, based on emulsion polyvinyl ch...

  10. High-density polyethylene-based composites with pressure-treated wood fibers

    OpenAIRE

    Lu Shang; Guangping Han; Fangzheng Zhu; Jiansheng Ding; Todd Shupe; Qingwen Wang; Qinglin Wu

    2012-01-01

    High-Density Polyethylene (HDPE)-based composites with alkaline copper quaternary (ACQ)- and micronized copper quaternary (MCQ)-treated wood fibers were manufactured through injection molding. The mechanical properties, water absorption, and biological resistance properties of the fabricated composites with different coupling treatments were investigated. Composites with ACQ- and MCQ-treated wood had mechanical properties comparable with those made of untreated wood. The different coupling ag...

  11. Biochar-based nano-composites for the decontamination of wastewater: A review.

    Science.gov (United States)

    Tan, Xiao-Fei; Liu, Yun-Guo; Gu, Yan-Ling; Xu, Yan; Zeng, Guang-Ming; Hu, Xin-Jiang; Liu, Shao-Bo; Wang, Xin; Liu, Si-Mian; Li, Jiang

    2016-07-01

    Synthesizing biochar-based nano-composites can obtain new composites and combine the advantages of biochar with nano-materials. The resulting composites usually exhibit great improvement in functional groups, pore properties, surface active sites, catalytic degradation ability and easy to separation. These composites have excellent abilities to adsorb a range of contaminants from aqueous solutions. Particularly, catalytic material-coated biochar can exert simultaneous adsorption and catalytic degradation function for organic contaminants removal. Synthesizing biochar-based nano-composites has become an important practice for expanding the environmental applications of biochar and nanotechnology. This paper aims to review and summarize the various synthesis techniques for biochar-based nano-composites and their effects on the decontamination of wastewater. The characteristic and advantages of existing synthesis methods are summarized and discussed. Application of biochar-based nano-composites for different contaminants removal and the underlying mechanisms are reviewed. Furthermore, knowledge gaps that exist in the fabrication and application of biochar-based nano-composites are also identified.

  12. The present status and key problems of carbon nanotube based polymer composites

    Directory of Open Access Journals (Sweden)

    2007-05-01

    Full Text Available The state-of-art and key problems of carbon nanotube (CNT based polymer composites (CNT/polymer composites including CNT/polymer structural composites and CNT/polymer functional composites are reviewed. Based on the results reported up to now, CNTs can be an effective reinforcement for polymer matrices, and the tensile strength and elastic modulus of CNT/polymer composites can reach as high as 3600 MPa and 80 GPa, respectively. CNT/polymer composites are also promising functional composite materials with improved electrical and thermal conductivity, etc. Due to their multi-functional properties, CNT/polymer composites are expected to be used as low weight structural materials, optical devices, thermal interface materials, electric components, electromagnetic absorption materials, etc. However, the full potential of CNT/polymer composites still remains to be realized. A few key problems, such as how to prepare structure-controllable CNTs with high purity and consistently dependable high performance, how to break up entangled or bundled CNTs and then uniformly disperse and align them within a polymer matrix, how to improve the load transfer from matrix to CNT reinforcement, etc, still exist and need to be solved in order to realize the wide applications of these advanced composites.

  13. Electron spectroscopy of rubber and resin-based composites containing 2D carbon

    Energy Technology Data Exchange (ETDEWEB)

    Kaciulis, S., E-mail: saulius.kaciulis@ismn.cnr.it [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Mezzi, A.; Balijepalli, S.K. [Institute for the Study of Nanostructured Materials, ISMN-CNR, P.O. Box 10, Monterotondo Stazione, 00015 Roma (Italy); Lavorgna, M. [Institute of Polymers, Composites and Biomaterials, IPCB-CNR, P.le Fermi, 80055 Napoli (Italy); Xia, H.S. [State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, 610065 Sichuan (China)

    2015-04-30

    Composite materials with 2D carbon (graphene and/or single wall carbon nanotubes) are very promising due to their extraordinary electrical and mechanical properties. Graphene and natural rubber composites, which may be used for the gaskets or sealants, were prepared by ultrasonically assisted latex-mixing exfoliation and in-situ reduction process, with two vulcanization approaches: roll-mixing and hot-pressing. Also the resin-based composites, filled with micro-particles of Ag and graphene or carbon nanotubes, have been studied. The standards for the compositional characterization of these materials still are not established. In addition to the mostly used techniques, such as Raman spectroscopy and electron microscopy, also Auger electron spectroscopy can be employed for the identification of graphene. In this study, the shape of C KVV peak, excited by electron beam and X-ray photons, has been investigated in different composite materials containing graphene and carbon nanotubes. A spectroscopic method for 2D carbon recognition, based on the D{sub x} parameter which is determined from C KVV signal excited by X-ray photons, was proposed and verified. Even a small content of graphene in different types of composites was sufficient for this recognition due to the dominating presence of graphene on the surface of composites. - Highlights: • Chemical composition of the rubber composites was determined by XPS. • Auger spectrum of carbon was used for graphene identification in composites. • Small content of graphene was sufficient for its recognition from the D parameter.

  14. Cubic boron nitride based composites for cutting applications

    Directory of Open Access Journals (Sweden)

    P. Klimczyk

    2011-02-01

    Full Text Available Purpose: The aim of our work was to obtain durable fined-grained cBN-Si3N4 composite with high values of hardness and fracture toughness, which can be successfully used as a cutting tool. Little quantity of the Si3N4 nanopowder fills up the porous between cBN grains thus result in resistance to crack propagation by means so called “crack deflection” mechanism.Design/methodology/approach: Two variants of the cBN-Si3N4 composites („I” – with micropowder cBN and „II” – with mixture of micro- and nanopowdes cBN contained 3% of nanodispersed Si3N4 powder, have been sintered at High Pressure – High Temperature (HPHT conditions. Basic physical-mechanical properties, phase composition and microstructure of sintered materials have been investigated.Findings: The comparison of the mechanical properties of cBN-Si3N4 (I and cBN-Si3N4 (II composites showed that the addition of 10% cBN nanopowder to mixture caused small increase in hardness from 4750 up to 4855 HV10 and decrease in Young’s modulus from 842 to 812 GPa. Fracture toughness of both type of composites is on the same level above 10 MPa∙m1/2.Research limitations/implications: High hardness of cBN-Si3N4 composites present a technical challenge in shaping of them. Commercial application of presented materials, e.g. cutting tools production, needs to develop a high efficient cutting, lapping and grinding techniques.Practical implications: The material obtained could be successfully applied for different cutting applications due to its favourable combination of hardness and fracture toughness.Originality/value: Commercial superhard materials, so called “high content cBN composites”, have usually 10-20 vol% of binding phase, often in the form of Ti or/and Al compounds. In the presented work only 3% of Si3N4 phase was used as a sintering aid. The high content of cBN phase allows to keep Young’s modulus and hardness values close to the theoretical ones for pure PcBN.

  15. Synthesis and characterization of polyethylene oxide based nano composite electrolyte

    Indian Academy of Sciences (India)

    M Malathi; K Tamilarasan

    2014-08-01

    Polyethylene oxide (PEO) – montmorillonite (MMT) composite electrolytes were synthesised by solution casting technique. The salt used for the study is Lithium perchlorate (LiClO4). The morphology and percentage of crystallinity data were obtained through X-ray Diffraction and Differential Scanning Caloriemetry. The ionic conductivity of the polymer electrolytes was studied by impedance spectroscopy. The addition of MMT resulted in an increase in conductivity over the temperature range of 25–60°C. The ionic conductivity of a composite polymer electrolyte containing 1.2 wt% MMT was 1 × 10-5 S cm−1 at 25°C, which is at least one order of magnitude higher than that of the polymer electrolyte (4 × 10-7S cm−1). The increase in ionic conductivity is explained on the basis of crystallinity of the polymer electrolyte.

  16. New transparent conductive metal based on polymer composite

    Energy Technology Data Exchange (ETDEWEB)

    Keshavarz Hedayati, Mehdi; Jamali, Mohammad [Nanochemistry and Nanoengineering, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University, Kiel (Germany); Strunkus, Thomas; Zaporochentko, Vladimir; Faupel, Franz [Multicomponent Materials, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University, Kiel (Germany); Elbahri, Mady [Nanochemistry and Nanoengineering, Institute for Materials Science, Faculty of Engineering, Christian-Albrechts-University, Kiel (Germany); Helmholtz-Zentrum Geesthacht GmbH, Institute of Polymer Research, Nanochemistry and Nanoengineering (Germany)

    2011-07-01

    Currently great efforts are made to develop new kind of transparent conductors (TCs) to replace ITO. In this regard different materials and composites have been proposed and studied including conductive polymers, carbon nanotubes (CNTs), metal grids, and random networks of metallic nanowires. But so far none of them could be used as a replacing material, since either they are either fragile and brittle or their electrical conductivity is below the typical ITO. Thin metallic films due to their high electrical conductivity could be one of the best replacing materials for ITO, however their poor transparency makes their application as TCs limited. Here we design and fabricate a new polymeric composite coating which enhances the transparency of the thin metal film up to 100% relative to the initial value while having a high electrical conductivity of typical metals. Therefore our proposed device has a great potential to be used as new transparent conductor.

  17. Underground fluid composition analysis based on the near infrared spectrum

    Science.gov (United States)

    Li, Wenxi; Liao, Yanbiao; Zhang, Min

    2011-11-01

    The near-infrared spectrum is very practical for real-time analyzing in the field of industry. This paper describes the structure of optical system, which is a part of the well logging instruments. The optical system is designed to analyze the composition of underground fluid, using the differences between oil and water in near-infrared absorption. Using Beer- Lambert law, the article analyzes the light intensity when broad-spectrum light passes through the liquid. According to the results of analysis, a group of wavelength including center wavelength and bandwidth can be selected. With each selected wavelength, light intensity changes significantly as the concentration of liquid changes. By measuring the light intensity, the system can analyse the composition of underground fluid.

  18. Flexible tactile sensing based on piezoresistive composites: a review.

    Science.gov (United States)

    Stassi, Stefano; Cauda, Valentina; Canavese, Giancarlo; Pirri, Candido Fabrizio

    2014-01-01

    The large expansion of the robotic field in the last decades has created a growing interest in the research and development of tactile sensing solutions for robot hand and body integration. Piezoresistive composites are one of the most widely employed materials for this purpose, combining simple and low cost preparation with high flexibility and conformability to surfaces, low power consumption, and the use of simple read-out electronics. This work provides a review on the different type of composite materials, classified according to the conduction mechanism and analyzing the physics behind it. In particular piezoresistors, strain gauges, percolative and quantum tunnelling devices are reviewed here, with a perspective overview on the most used filler types and polymeric matrices. A description of the state-of-the-art of the tactile sensor solutions from the point of view of the architecture, the design and the performance is also reviewed, with a perspective outlook on the main promising applications. PMID:24638126

  19. Flexible tactile sensing based on piezoresistive composites: a review.

    Science.gov (United States)

    Stassi, Stefano; Cauda, Valentina; Canavese, Giancarlo; Pirri, Candido Fabrizio

    2014-03-14

    The large expansion of the robotic field in the last decades has created a growing interest in the research and development of tactile sensing solutions for robot hand and body integration. Piezoresistive composites are one of the most widely employed materials for this purpose, combining simple and low cost preparation with high flexibility and conformability to surfaces, low power consumption, and the use of simple read-out electronics. This work provides a review on the different type of composite materials, classified according to the conduction mechanism and analyzing the physics behind it. In particular piezoresistors, strain gauges, percolative and quantum tunnelling devices are reviewed here, with a perspective overview on the most used filler types and polymeric matrices. A description of the state-of-the-art of the tactile sensor solutions from the point of view of the architecture, the design and the performance is also reviewed, with a perspective outlook on the main promising applications.

  20. Flexible Tactile Sensing Based on Piezoresistive Composites: A Review

    Directory of Open Access Journals (Sweden)

    Stefano Stassi

    2014-03-01

    Full Text Available The large expansion of the robotic field in the last decades has created a growing interest in the research and development of tactile sensing solutions for robot hand and body integration. Piezoresistive composites are one of the most widely employed materials for this purpose, combining simple and low cost preparation with high flexibility and conformability to surfaces, low power consumption, and the use of simple read-out electronics. This work provides a review on the different type of composite materials, classified according to the conduction mechanism and analyzing the physics behind it. In particular piezoresistors, strain gauges, percolative and quantum tunnelling devices are reviewed here, with a perspective overview on the most used filler types and polymeric matrices. A description of the state-of-the-art of the tactile sensor solutions from the point of view of the architecture, the design and the performance is also reviewed, with a perspective outlook on the main promising applications.

  1. Flexible Tactile Sensing Based on Piezoresistive Composites: A Review

    OpenAIRE

    Stefano Stassi; Valentina Cauda; Giancarlo Canavese; Candido Fabrizio Pirri

    2014-01-01

    The large expansion of the robotic field in the last decades has created a growing interest in the research and development of tactile sensing solutions for robot hand and body integration. Piezoresistive composites are one of the most widely employed materials for this purpose, combining simple and low cost preparation with high flexibility and conformability to surfaces, low power consumption, and the use of simple read-out electronics. This work provides a review on the different type of c...

  2. A Planning-based Approach for Music Composition

    OpenAIRE

    Velardo, Valerio; Vallati, Mauro

    2015-01-01

    . Automatic music composition is a fascinating field within computational creativity. While different Artificial Intelligence techniques have been used for tackling this task, Planning – an approach for solving complex combinatorial problems which can count on a large number of high-performance systems and an expressive language for describing problems – has never been exploited. In this paper, we propose two different techniques that rely on automated planning for generatin...

  3. EMI shielding composites based on magnetic nanoparticles and nanocarbons

    OpenAIRE

    Crespo Ribadeneyra, María

    2014-01-01

    The response of nanocomposites towards electromagnetic (EM) radiation can be tailored through the electrical conductivity, permittivity and magnetic permeability. Several composites with singular microstructures and containing either conductive nanoinclusions, magnetic nanoparticles or the combination of both, have been prepared and characterized. The performance of our materials as EM interference (EMI) shields, has been determined from 1 to 18 GHz and elucidated in terms of their electric a...

  4. Graph-based matching of composite OWL-S services

    OpenAIRE

    Cuzzocrea, Alfredo; De Coi, Juri Luca; Fisichella, Marco; Skoutas, Dimitrios

    2011-01-01

    International audience Existing techniques for Web service discovery focus mainly on matching functional parameters of atomic services, such as inputs and outputs. However, one of the main advantages of Web services is that they are often composed into more complex processes to achieve a given goal. Applying such techniques in these cases, ignores the workflow structure of the composite process, and therefore may produce matches that are not very accurate. To overcome this limitation, we p...

  5. Micromechanics Based Design/Analysis Codes for Advanced Composites

    Science.gov (United States)

    Mital, Subodh K.; Murthy, Pappu L. N.; Gyekenyesi, John P.

    2002-01-01

    Advanced high temperature Ceramic Matrix Composites (CMC) hold an enormous potential for use in aero and space related applications specifically for propulsion system components. Consequently, this has led to a multitude of research activities pertaining to fabrication, testing and modeling of these materials. The efforts directed at the development of ceramic matrix composites have focused primarily on improving the properties of the constituents as individual phases. It has, however, become increasingly clear that for CMC to be successfully employed in high temperature applications, research and development efforts should also focus on optimizing the synergistic performance of the constituent phases within the as-produced microstructure of the complex shaped CMC part. Despite their attractive features, the introduction of these materials in a wide spectrum of applications has been excruciatingly slow. The reasons are the high costs associated with the manufacturing and a complete experimental testing and characterization of these materials. Often designers/analysts do not have a consistent set of necessary properties and design allowables to be able to confidently design and analyze structural components made from these composites. Furthermore, the anisotropy of these materials accentuates the burden both on the test engineers and the designers by requiring a vastly increased amount of data/characterization compared to conventional materials.

  6. Highly energetic compositions based on functionalized carbon nanomaterials

    Science.gov (United States)

    Yan, Qi-Long; Gozin, Michael; Zhao, Feng-Qi; Cohen, Adva; Pang, Si-Ping

    2016-02-01

    In recent years, research in the field of carbon nanomaterials (CNMs), such as fullerenes, expanded graphite (EG), carbon nanotubes (CNTs), graphene, and graphene oxide (GO), has been widely used in energy storage, electronics, catalysts, and biomaterials, as well as medical applications. Regarding energy storage, one of the most important research directions is the development of CNMs as carriers of energetic components by coating or encapsulation, thus forming safer advanced nanostructures with better performances. Moreover, some CNMs can also be functionalized to become energetic additives. This review article covers updated preparation methods for the aforementioned CNMs, with a more specific orientation towards the use of these nanomaterials in energetic compositions. The effects of these functionalized CNMs on thermal decomposition, ignition, combustion and the reactivity properties of energetic compositions are significant and are discussed in detail. It has been shown that the use of functionalized CNMs in energetic compositions greatly improves their combustion performances, thermal stability and sensitivity. In particular, functionalized fullerenes, CNTs and GO are the most appropriate candidate components in nanothermites, solid propellants and gas generators, due to their superior catalytic properties as well as facile preparation methods.

  7. Rolling contact fatigue testing of peek based composites

    Directory of Open Access Journals (Sweden)

    Petrogalli C.

    2010-06-01

    Full Text Available Rolling contact fatigue phenomenon was investigated on unfilled PEEK and on three different PEEK composites: 10% carbon micro-fiber, graphite and PTFE filled matrix, 30% carbon micro-fiber filled matrix, 30% glass micro-fiber filled matrix. For this aim, roller-shaped specimens were machined from extruded bars of these materials and subjected to rolling contact tests at different contact pressure levels by means of a four roller machine. Contact pressure-life diagrams and wear rates were so obtained and compared, highlighting a relationship with monotonic and hardness materials properties. Microscopic observations of contact surfaces and transversal section of the specimens also allowed observing the damage mechanisms occurred in the materials tested and the effects of the filler. In particular way, deep radial cracks appeared on unfilled PEEK, while spalling and delamination phenomena where found on composites. Diffuse microcracks were found at the filler-matrix interface of the composites specimens, confirming that the fatigue life of these materials is essentially determined by the crack propagation phase, also under rolling contact loading.

  8. BlenX-based compositional modeling of complex reaction mechanisms

    Directory of Open Access Journals (Sweden)

    Judit Zámborszky

    2010-02-01

    Full Text Available Molecular interactions are wired in a fascinating way resulting in complex behavior of biological systems. Theoretical modeling provides a useful framework for understanding the dynamics and the function of such networks. The complexity of the biological networks calls for conceptual tools that manage the combinatorial explosion of the set of possible interactions. A suitable conceptual tool to attack complexity is compositionality, already successfully used in the process algebra field to model computer systems. We rely on the BlenX programming language, originated by the beta-binders process calculus, to specify and simulate high-level descriptions of biological circuits. The Gillespie's stochastic framework of BlenX requires the decomposition of phenomenological functions into basic elementary reactions. Systematic unpacking of complex reaction mechanisms into BlenX templates is shown in this study. The estimation/derivation of missing parameters and the challenges emerging from compositional model building in stochastic process algebras are discussed. A biological example on circadian clock is presented as a case study of BlenX compositionality.

  9. Designing of the chemical composition of steels basing on the hardenability of constructional steels

    International Nuclear Information System (INIS)

    The paper presents the original method of modelling of the relationships between chemical composition of alloy constructional steel and its hardenability, employing neural networks. Basing on the experimental results of the hardenability investigations, which employed Jominy method, the model of the neural networks was developed and fully verified experimentally. The model makes it possible to obtain Jominy hardenability curves basing on the steel chemical composition. The model of neural networks, making it possible to design the steel chemical composition, basing on the known Jominy hardenability curve shape, was developed also and fully verified numerically. (author)

  10. X-RAY BASED MICROMECHANICAL FINITE ELEMENT MODELING OF COMPOSITE MATERIALS

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard; Emerson, Monica Jane; Jespersen, Kristine Munk;

    2016-01-01

    This is a study of a uni-directional non-crimp fabric reinforced epoxy composite material typically used as the load carrying laminate in wind turbine blades. Based on a 3D xray tomography scan, the bundle and fibre/matrix structure of the composite is segmented. This segmentation is used...

  11. Copper-decorated carbon nanotubes-based composite electrodes for nonenzymatic detection of glucose

    OpenAIRE

    Pop, A.(National Institute for Physics and Nuclear Engineering, Bucharest, Romania); Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.

    2012-01-01

    The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite electrode (Cu/CNT-epoxy) exhibited the highest sensitivity to glucose determination.

  12. Creativity, Originality, Identity: Investigating Computer-Based Composition in the Secondary School

    Science.gov (United States)

    Mellor, Liz

    2008-01-01

    This article investigates computer-based music composition using the CD Rom "Dance eJay" with pupils from a secondary school setting (13-15 years). Three issues are explored: the extent to which participants adopted different strategies during the composition process, how the strategies differed with respect to prior experience of formal…

  13. Analysis of revenue improvements with runtime adaptation of service composition based on conditional request retries

    NARCIS (Netherlands)

    Zivkovic, M.; Berg, J.L. van den

    2012-01-01

    In this paper we consider the runtime service adaptation mechanism for service compositions that is based on conditional retries. A single retry may be issued while a concrete service within composition is executed. This retry could either invoke the same concrete service or a functionally equivalen

  14. Bidirectional current-voltage converters based on magnetostrictive/piezoelectric composites

    NARCIS (Netherlands)

    Jia, Y.; Or, S.W.; Chan, H.L.W.; Jiao, J.; Luo, H.; Van der Zwaag, S.

    2009-01-01

    We report a power supply-free, bidirectional electric current-voltage converter based on a coil-wound laminated composite of magnetostrictive alloy and piezoelectric crystal. An electric current applied to the coil induces a magnetic field, resulting in an electric voltage from the composite due to

  15. Copper-decorated carbon nanotubes-based composite electrodes for nonenzymatic detection of glucose

    NARCIS (Netherlands)

    Pop, A.; Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.

    2012-01-01

    The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite

  16. Impedance spectroscopy of composites based on waste polymeric materials for electrical engineering purposes

    Science.gov (United States)

    Zubko, V. I.; Zubko, D. V.

    2012-07-01

    We have developed a high-sensitivity capacitance transducer and a method for measuring the complex of electrical indices of composites based on waste polymeric materials in the frequency range from 100 Hz to 1 MHz. The electrical properties of composites depending on the electric field frequency and the content and type of the filler have been investigated.

  17. Carbon-based Composite Electrodes: Preparation, Characterization and Application in Electroanalysis

    NARCIS (Netherlands)

    Corb, I.; Manea, F.; Radovan, C.; Pop, A.; Burtica, G.; Malchev, P.G.; Picken, S.J.; Schoonman, J.

    2007-01-01

    Electrodes based on carbon, i.e., expanded graphite (20%, wt.)-epoxy composite (20EG-Epoxy) and expanded graphite (20%, wt.)-polystyrene composite (20EG-PS) have been prepared, characterized using scanning electron microscopy (SEM) and cyclic voltammetry (CV), and tested as anodic sensors. The elect

  18. Vibration based structural health monitoring of a composite plate with stiffeners

    NARCIS (Netherlands)

    Loendersloot, R.; Ooijevaar, T.H.; Warnet, L.; Boer, de A.; Akkerman, R.

    2010-01-01

    A vibration based damage identification algorithm is implemented to assess the damage of a thin-walled composite structure. The structure analysed is a skin with stiffeners, as frequently applied in aircraft components. Both experimental and numerical studies on a single composite skin--stiffener st

  19. School-Based BMI and Body Composition Screening and Parent Notification in California: Methods and Messages

    Science.gov (United States)

    Madsen, Kristine A.; Linchey, Jennifer

    2012-01-01

    Background: School-based body mass index (BMI) or body composition screening is increasing, but little is known about the process of parent notification. Since 2001, California has required annual screening of body composition via the FITNESSGRAM, with optional notification. This study sought to identify the prevalence of parental notification…

  20. A Composite Heterostructure Mesh-shaped Patch Antenna Based on Left Handed Material

    Directory of Open Access Journals (Sweden)

    Ji jun Wang

    2014-01-01

    Full Text Available In this paper, a composite heterostructure mesh-shaped patch antenna based on left handed material (LHM is presented. The method of finite difference time domain (FDTD is used. The results show that electromagnetic wave resonance occurs near 4.52 GHz, where the equivalent permittivity and permeability of composite material are both negative. The composite antenna’s gain improves 9.047 dB, its return loss reduces 20.26 dB compared to the conventional antenna’s ones. The results indicate that this composite patch antenna system can reduce return loss of the antenna and increase the gain obviously.

  1. Study Of Ceramic-Polymer Composites Reliability Based On The Bending Strength Test

    Directory of Open Access Journals (Sweden)

    Walczak Agata

    2015-11-01

    Full Text Available In this paper the reliability assessment of structural reliability of the selected light-cured dental composites based on the biaxial flexural strength test results has been presented. A two-parameter Weibull distribution was applied as a reliability model in order to estimate probability of strength maintenance in the analysed population. Weibull distribution parameters were interpreted as a characteristic material strength (scale parameter and structural reliability parameter in terms of ability to maintain strength by each of specimen from the general population (shape parameter. 20 composite specimens underwent strength tests, including 2 “flow” type composites and 2 standard composites (with typical filler content. “Flow” type composites were characterized with lower characteristic strength and higher structural reliability comparing to other studied composites.

  2. Improvement of Water Sensitivity of Macro-defect-free Cement Based Composites with Cross Coupling Agent

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The enhancement of interface bonding between cement and polymer and the structural reticulation of the water-soluble polymer are proposed to minimize the shortening of the mechanical properties of macro-defect-free (MDF) cement based composites at high relative humidity. The MDF composites incorporated with various cross-coupling agents were studied experimentally. The results show that the MDF composites modified with small amounts of cross-coupling agent had raised mechanical properties, but it is more important that the modified MDF composites had a significant increase in water resistance compared to the original one. In the meantime if the water resistant material such as fine powder of α-alumina was used to substitute for the unreacted cement grains in the MDF composites, a more efficient improvement of water resistance would be obtained. The loss in flexural strength of the MDF composites after 90 days of water immersion decreased from 62% before unmodified to 15% after modified.

  3. Solid Particle Erosion response of fiber and particulate filled polymer based hybrid composites: A review

    Directory of Open Access Journals (Sweden)

    Yogesh M

    2016-01-01

    Full Text Available The solid particle erosion behaviour of fiber and particulate filled polymer composites has been reviewed. An overview of the problem of solid particle erosion was given with respect to the processes and modes during erosion with focus on polymer matrix composites. The new aspects in the experimental studies of erosion of fiber and particulate filled polymer composites were emphasized in this paper. Various predictions and models proposed to describe the erosion rate were listed and their suitability was mentioned. Implementation of design of experiments and statistical techniques in analyzing the erosion behaviour of composites was discussed. Recent findings on erosion response of multi-component hybrid composites were also presented. Recommendations were given on how to solve some open questions related to the structureerosion resistance relationships for polymers and polymer based hybrid composites.

  4. Preparation and characterization of a novel ionizing electromagnetic radiation shielding material: Hematite filled polyester based composites

    International Nuclear Information System (INIS)

    Isophthalic polyester (PES) based and natural mineral (hematite) filled composites were prepared and characterized for ionizing electromagnetic radiation shielding applications. Density evaluation and microscopic studies of the composites were carried out. Shielding performances of the composites were investigated for three different IEMR energy regions as low, intermediate and high. The mass attenuation coefficient of the prepared composites reached 98% of the elemental lead. In addition, the studied composites were superior to lead by virtue of their non-toxic nature. - Highlights: • Isophytalitic polyester-natural mineral (hematite) filled composites were prepared. • Ionizing electromagnetic radiation shielding performances were investigated. • Density evaluation and microscopic studies were carried out. • Attenuation coefficients were determined for different energies. • The mass attenuation coefficients reached 98% of the elemental lead

  5. Anisotropic tensile properties of tungsten fiber reinforced Zr based metallic glass composites

    International Nuclear Information System (INIS)

    The tensile properties and deformation behaviors of Zr based metallic glass composites containing different tungsten fiber orientations were investigated. The angles (θf) between tungsten fiber orientation and loading axial direction are 0°, 15°, 30°, 45°, 60°, 75° and 90°, respectively. The results show that the strength and the failure modes vary with θf. The tensile strength of the composite decreases as the θf increases. The tensile strength of the composite at θf=90° is only 253 MPa. The plasticity of all the composites do not be improved. The composites failed approximately 90° normal fault at θf=0°/15°, while the composites failed along the tungsten fiber when the θf is bigger than or equal to 30° because of the low axial grain boundary strength of the elongated W grains

  6. High-density polyethylene-based composites with pressure-treated wood fibers

    Directory of Open Access Journals (Sweden)

    Lu Shang

    2012-11-01

    Full Text Available High-Density Polyethylene (HDPE-based composites with alkaline copper quaternary (ACQ- and micronized copper quaternary (MCQ-treated wood fibers were manufactured through injection molding. The mechanical properties, water absorption, and biological resistance properties of the fabricated composites with different coupling treatments were investigated. Composites with ACQ- and MCQ-treated wood had mechanical properties comparable with those made of untreated wood. The different coupling agents worked well for the treated wood materials. Similar water absorption behaviors were observed for the HDPE composites containing treated wood and those containing untreated wood. The results of the termite test showed that the composites containing untreated wood had slightly more weight loss. The decay test revealed that the composites containing treated wood had less decay fungal growth on the surfaces, compared with samples from untreated wood, indicating enhanced decay resistance for the composites from the treated material. The stable mechanical properties and improved biological performances of the composites containing treated wood demonstrated the feasibility of making wood-plastic composites with pressure-treated wood materials, and thus offered a practical way to recycle treated wood into value-added composites.

  7. Laser beam drilling of metal-based composites

    Science.gov (United States)

    Riegel, H.; Merkel, M.; Ã-chsner, A.

    2014-02-01

    Laser drilling is a highly efficient technique to generate holes in almost any material. The relatively small amount of heat being involved during the process results in a small heat affected zone. This characteristic makes laser processing interesting for composite materials. The drilling process has to be adapted to the special characteristics of the composite material. In this paper investigations were performed with an advanced composite material, that is a metallic hollow sphere structure (MHSS). Numerical simulation was used to predict heat flux and temperature levels for different geometric parameters of the spheres (diameter, wall thickness) in order to optimize the drilling process. The numerical simulation allows a detailed analysis of the physical process in the zone that is influenced by the laser beam, which can hardly be analyzed by any measuring technique. The models for transient numerical analysis consider heat conduction and convection. The experimental work was done by a CO2-laser. The percussion drilling method has been used as drilling technique. The pulse duration was in the millisecond time regime. Investigations have been done with a mean power of 100 W, 200 W and 400 W. Two focal lenses have been used with focal lengths of 5.0´´ and 7.5´´. The laser beam melts the hollow sphere structure inside the beam leaving a hole in the structure as well as in individual hollow spheres. An image processing technique was developed to determine the circularity on the spheres and the drilled diameter in the structure. The circularity declines with increasing drill depth. The diameter as function of depth can be well described with lines of constant intensity of the focussed laser beam, the isophotes.

  8. A Compositive Information Collection Platform System Based on Web Service

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The aim is to solve the problem that how to share dispersive and heterogeneous data inside business information system or some other information source. On the basis of Web service, this paper adopts the notion of Data As Service to build service-oriented data integration architecture. According to this architecture, we develop data collection system which effectively integrates data from heterogeneous information source and present a uniform data view to end users by implementing sharing data from heterogeneous systems and information source .At last, this paper gives an example of a compositive information collection platform system.

  9. Photoinduced variable stiffness of spiropyran-based composites

    International Nuclear Information System (INIS)

    A quantitative demonstration of reversible stiffness upon appropriate light stimulus in a spiropyran-polymeric composite is presented. The polymeric films containing 3% wt. of the photochromic spiropyran were irradiated with alternating ultraviolet and visible light and the storage modulus was measured. A reversible change in modulus of about 7% was observed. The modulus change was attributed to an interaction of the polar merocyanine with the polymeric chains and/or to a variation of effective free volume induced by merocyanine aggregates formed in the polymer upon ultraviolet irradiation. The effect is fully reversed when the merocyanine isomers turn back to the spiropyran state after visible irradiation.

  10. Properties of Natural Rubber-Based Composites Containing Fullerene

    Directory of Open Access Journals (Sweden)

    Omar A. Al-Hartomy

    2012-01-01

    Full Text Available In this study the influence of fullerenes in concentrations from 0.5 to 1.5 phr on both the vulcanization characteristics of the compounds and physicomechanical, dynamic, and dielectric properties and thermal aging resistance of nanocomposites on the basis of natural rubber has been investigated. The effect of the filler dispersion in the elastomeric matrix has been also investigated. Neat fullerene and the composites comprising it have been studied and characterized by scanning electron microscopy (SEM and transmission electron microscopy (TEM.

  11. Carbon Nanotube-Conducting Polymer Composites Based Solar Cells

    Institute of Scientific and Technical Information of China (English)

    Prakash; R.Somani; M.Umeno

    2007-01-01

    1 Results Combination of carbon nanotubes (CN) with polymers is important for application towards value added composites,solar cells,fuel cells etc.Especially interesting is the combination of CN with π-conjugated polymers because of the potential interaction between the highly delocalized π-electrons of the CN and the π-electrons correlated with the lattice of polymer skeleton.Efficient exciton dissociation due to electron transfer from the photoexcited polymer to CN is of interest for photovoltaic app...

  12. Photocatalytic composites based on titania nanoparticles and carbon nanomaterials

    Science.gov (United States)

    Nguyen, Bich Ha; Hieu Nguyen, Van; Vu, Dinh Lam

    2015-09-01

    In this article we present a review on recent experimental works toward the formation of visible light responsive composite photocatalysts on the basis of titania nanoparticles and carbon nanomaterials of different types. The research results achieved in last years has shown that the nanocomposite photocatalysts comprising titania nanoparticles and graphene or graphene oxide sheets, and also nanoparticles of noble metals and metallic oxides, exhibited the evident priority compared to the others. Therefore our review emphasizes the research on these promising visible light responsive nanophotocatalysts.

  13. Effect of pre-heating on the mechanical properties of silorane-based and methacrylate-based composites

    Science.gov (United States)

    Mohammadi, Narmin; Jafari-Navimipour, Elmira; Kimyai, Soodabeh; Ajami, Amir-Ahmad; Bahari, Mahmoud; Ansarin, Mohammad

    2016-01-01

    Background The use of composites in dental restoration has been commonly criticized, due to their underwhelming mechanical properties. This problem may be solved partially by preheating. The present research aims to determine the effect of preheating on the mechanical properties of two different classes of composites. Material and Methods A Silorane-based (Silorane) and a Methacrylate-based (Z250) composite were preheated to different temperatures (25, 37, and 68 °C) and afterwards were tested with the appropriate devices for each testing protocol. The material’s flexural strength, elastic modulus, and Vickers microhardness were evaluated. Two-way ANOVA, and Tukey’s post hoc were used to analyze the data. Results Microhardness and elastic modulus increased with preheating, while flexural strength values did not increase significantly with preheating. Furthermore the methacrylate-based composite (Z250) showed higher values compared to the Silorane-based composite (Silorane) in all the tested properties. Conclusions Preheating Silorane enhances the composite’s microhardness and elastic modulus but does not affect its flexural strength. On the other hand, preheating Z250 increases its microhardness but does not change its flexural strength or elastic modulus. In addition, the Z250 composite shows higher microhardness and flexural strength than Silorane, but the elastic modulus values with preheating are similar. Therefore Z250 seems to have better mechanical properties making it the better choice in a clinical situation. Key words:Composite, elastic modulus, flexural strength, microhardness, preheating. PMID:27703604

  14. Characterization of fabricated cobalt-based alloy/nano bioactive glass composites.

    Science.gov (United States)

    Bafandeh, Mohammad Reza; Gharahkhani, Raziyeh; Fathi, Mohammad Hossein

    2016-12-01

    In this work, cobalt-based alloy/nano bioactive glass (NBG) composites with 10, 15 and 20wt% NBG were prepared and their bioactivity after immersion in simulated body fluid (SBF) for 1 to 4weeks was studied. Scanning electron microscopy images of two- step sintered composites revealed relatively dense microstructure. The results showed that density of composite samples decreased with increase in NBG amount. The microstructure analysis as well as energy dispersive X-ray analysis (EDX) revealed that small amount of calcium phosphate phases precipitates on the surface of composite samples after 1week immersion in SBF. After 2weeks immersion, considerable amounts of cauliflower-like shaped precipitations were seen on the surface of the composites. Based on EDX analysis, these precipitations were composed mainly from Ca, P and Si. The observed bands in the Fourier transform infrared spectroscopy of immersed composites samples for 4weeks in SBF, were characteristic bands of hydroxyapatite. Therefore it is possible to form hydroxyapatite layer on the surface of composite samples during immersion in SBF. The results indicated that prepared composites unlike cobalt-based alloy are bioactive, promising their possibility for implant applications.

  15. Dynamic mechanical properties of PTFE-based composites filled with multi-component

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To improve performance of PTFE-based damping material, composites with several fillers were prepared by compressing and sintering. The dynamic mechanical properties of the composites were investigated by means of viscoanalyser. Temperature-dependent loss factors, storage modulus and loss modulus were obtained.And SEM was employed to study the compatibility between PTFE and fillers. The results show that, when blending PPS and PEEK at proper content, the loss factor curve appears double peaks, which can widen the high-damping temperature region of the composites. Blending graphite or alumina can increase the storage modulus obviously, but decrease the value of loss factor. And because graphite or alumina combines with matrix poorly, glide would happen at interface when bearing external load. The interface friction can dissipate vibration energy, which increases the loss modulus of the composites. Blending PPS, PEEK and graphite or alumina at right content, PTFE-based composites can meet demands as damping material in practical engineering.

  16. Epoxy Resin Based Composites, Mechanical and Tribological Properties: A Review

    Directory of Open Access Journals (Sweden)

    S.A. Bello

    2015-12-01

    Full Text Available High fuel consumption by automobile and aerospace vehicles built from legacy alloys has been a great challenge to global design and material engineers. This has called for researches into material development for the production of lighter materials of the same or even superior mechanical properties to the existing materials in this area of applications. This forms a part of efforts to achieve the global vision 2025 i.e to reduce the fuel consumption by automobile and aerospace vehicles by at least 75 %. Many researchers have identified advanced composites as suitable materials in this regard. Among the common matrices used for the development of advanced composites, epoxy resin has attained a dominance among its counterparts because of its excellent properties including chemical, thermal and electrical resistance properties, mechanical properties and dimensional stability. This review is a reflection of the extensive study on the currently ongoing research aimed at development of epoxy resin hybrid nanocomposites for engineering applications. In this paper, brief explanation has been given to different terms related to the research work and also, some previous works (in accordance with materials within authors’ reach in the area of the ongoing research have been reported.

  17. Fabrication of Biosensor Based on Polyaniline/Gold Nanorod Composite

    Directory of Open Access Journals (Sweden)

    Uğur Tamer

    2011-01-01

    Full Text Available This present paper describes a new approach to fabricate a new amperometric sensor for the determination of glucose. Polyaniline (PANI film doped with colloidal gold nanorod particles has been used to immobilize glucose oxidase by glutaraldehyde. The polyaniline/gold nanorod composite structure gave an excellent matrix for enzyme immobilization due to the large specific surface area and higher electroactivity. The composite has been characterized by cyclic voltammetry (CV, scanning electron microscopy (SEM, and surface-enhanced Raman spectroscopy (SERS. The SERS spectrum of the surface-immobilized glucose oxidase and the spectrum of the native enzyme indicate that the main feature of the native structure of glucose oxidase was conserved after being immobilized on the polymer matrix. The amperometric response was measured as a function of concentration of glucose at a potential of 0.6 V versus Ag/AgCl in 0.1 M phosphate buffer at pH 6.4. Linear range of the calibration curve was from 17.6 μM to 1 mM with a sensitivity of 13.8 μA⋅mM−1⋅cm−2 and a limit of detection (LOD of 5.8 μM. The apparent Michaelis-Menten constant KM was calculated as 1.0 mM and the response time was less than 3 seconds.

  18. Justification of radiation protection fillers based composite materials fosfogipsum binding materials

    OpenAIRE

    Голов, Константин Сергеевич; Иванов, Валерий Анатолиевич; Мисовец, Юрий Викторович

    2012-01-01

    The results of comparative experimental studies of the effect of various radiation protection (RP) fillers of composite materials based on their fosfogipsum binding properties of RP From the analysis of results of experimental studies of the effect of various rare-earth filling of composite materials based on their binding fosfogipsum protective properties may be concluded. Barium sulfate as the RE filler plaster matrix displays technological instability in the manufacturing process of the co...

  19. Thermal Stability and Flammability of Styrene-Butadiene Rubber-Based (SBR) Ceramifiable Composites

    OpenAIRE

    Rafał Anyszka; Dariusz M. Bieliński; Zbigniew Pędzich; Przemysław Rybiński; Mateusz Imiela; Mariusz Siciński; Magdalena Zarzecka-Napierała; Tomasz Gozdek; Paweł Rutkowski

    2016-01-01

    Ceramifiable styrene-butadiene (SBR)-based composites containing low-softening-point-temperature glassy frit promoting ceramification, precipitated silica, one of four thermally stable refractory fillers (halloysite, calcined kaolin, mica or wollastonite) and a sulfur-based curing system were prepared. Kinetics of vulcanization and basic mechanical properties were analyzed and added as Supplementary Materials. Combustibility of the composites was measured by means of cone calorimetry. Their t...

  20. Experimental Evaluation of Biodegradable Film Compositions Based on Gelatin with Colchicine.

    Science.gov (United States)

    Bokeriya, L A; Bokeriya, O L; Sivtsev, V S; Novikova, S P; Salokhedinova, R R; Nikolashina, L N; Samsonova, N N; Gorodkov, A Yu; Serov, R A

    2016-07-01

    Biodegradable film compositions based on natural biopolymer gelatin with immobilized colchicine were prepared and their efficiency in prevention of the adhesion process in the pericardium was evaluated on rabbit model of postoperative pericarditis. The use of gelatin-based biodegradable film compositions significantly reduced the intensity of adhesion formation in the pericardial cavity, while immobilization of anti-inflammatory drug colchicine amplified their anti-adhesion activity. PMID:27496036

  1. Comparison of Polymerization Shrinkage in Methacrylate and Silorane-Based Composites Cured by different LEDs

    Directory of Open Access Journals (Sweden)

    Ayob Pahlavan

    2013-04-01

    Full Text Available Background and Aims: Polymerization shrinkage in Methacrylate-based composite is one of the most important factors in composite restorations failure. Silorane-based composite is introduced to compensate this drawback and claimed to have low shrinkage. The aim of this study was to evaluate the polymerization shrinkage of these two composites. Materials and Methods: In this experimental study, 5 disk shape samples for each resin composites were placed in the centre of metallic ring bonded to microscopic glass slab. Top surface of ring was covered by a glass cover slip. Glass slab and sample were placed on a special LVDT holder in order to light cure from bottom surface and to measure the polymerization shrinkage. In this study, Deflecting Disk method and LVDT (linear variable differential transducer was used for dimensional change measurement of resin composites. In this study, two LED curing units were used for composite polymerization. Results: The mean of polymerization shrinkage in Z250 cured with LED and High Power LED was 11.15±0.08µm and 11.51±0.17µm, respectively (P=0.094, and in P90 cured with LED and High Power LED was 1.08±0.06µm and 1.16±0.12µm, respectively (P=0.019. Conclusion: Silorane-based composite (P90 showed significantly less polymerization shrinkage than that of methacrylate-based composite (Z250. For the two types of composite, there was no significant difference between the two curing units in polymerization shrinkage.

  2. Potentiality of the composite fulleren based carbon films as the stripper foils for tandem accelerators

    CERN Document Server

    Vasin, A V; Rusavsky, A V; Totsky, Y I; Vishnevski, I N

    2001-01-01

    The problem of the radiation resistance of the carbon stripper foils is considered. The short review of the experimental data available in literature and original experimental results of the are presented. In the paper discussed is the possibility of composite fulleren based carbon films to be used for preparation of the stripper foils. Some technological methods for preparation of composite fulleren based carbon films are proposed. Raman scattering and atom force microscopy were used for investigation of the fulleren and composite films deposited by evaporation of the C sub 6 sub 0 fulleren powder.

  3. Formation of Porous Apatite Layer during In Vitro Study of Hydroxyapatite-AW Based Glass Composites

    Directory of Open Access Journals (Sweden)

    Pat Sooksaen

    2015-01-01

    Full Text Available This research discussed the fabrication, characterization, and in vitro study of composites based on the mixture of hydroxyapatite powder and apatite-wollastonite (AW based glass. AW based glass was prepared from the SiO2-CaO-MgO-P2O5-CaF2 glass system. This study focuses on the effect of composition and sintering temperature that influences the properties of these composites. Microstructural study revealed the formation of apatite layer on the composite surfaces when immersed in simulated body fluid (SBF solution at 37°C. Composites containing ≥50 wt% AW based glass showed good bioactivity after 7 days of immersion in the SBF. A porous calcium phosphate (potentially hydroxycarbonate apatite, HCA layer formed at the SBF-composite interface and the layer became denser at longer soaking period, for periods ranging from 7 to 28 days. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES analysis showed that early stage of soaking occurred with the release of Ca and Si ions from the composites and the decrease of P ions with slow exchange rate.

  4. Enhanced dielectric constant for efficient electromagnetic shielding based on carbon-nanotube-added styrene acrylic emulsion based composite.

    Science.gov (United States)

    Li, Yong; Chen, Changxin; Li, Jiang-Tao; Zhang, Song; Ni, Yuwei; Cai, Seng; Huang, Jie

    2010-01-01

    An efficient electromagnetic shielding composite based on multiwalled carbon nanotubes (MWCNTs)-filled styrene acrylic emulsion-based polymer has been prepared in a water-based system. The MWCNTs were demonstrated to have an effect on the dielectric constants, which effectively enhance electromagnetic shielding efficiency (SE) of the composites. A low conductivity threshold of 0.23 wt% can be obtained. An EMI SE of ~28 dB was achieved for 20 wt% MWCNTs. The AC conductivity (σac) of the composites, deduced from imaginary permittivity, was used to estimate the SE of the composites in X band (8.2-12.4 GHz), showing a good agreement with the measured results. PMID:20596498

  5. Enhanced Dielectric Constant for Efficient Electromagnetic Shielding Based on Carbon-Nanotube-Added Styrene Acrylic Emulsion Based Composite

    Directory of Open Access Journals (Sweden)

    Chen Changxin

    2010-01-01

    Full Text Available Abstract An efficient electromagnetic shielding composite based on multiwalled carbon nanotubes (MWCNTs-filled styrene acrylic emulsion-based polymer has been prepared in a water-based system. The MWCNTs were demonstrated to have an effect on the dielectric constants, which effectively enhance electromagnetic shielding efficiency (SE of the composites. A low conductivity threshold of 0.23 wt% can be obtained. An EMI SE of ~28 dB was achieved for 20 wt% MWCNTs. The AC conductivity (σ ac of the composites, deduced from imaginary permittivity, was used to estimate the SE of the composites in X band (8.2–12.4 GHz, showing a good agreement with the measured results.

  6. Photoconductive and nonlinear optical properties of composites based on metallophthalocyanines

    Science.gov (United States)

    Vannikov, A. V.; Grishina, A. D.; Gorbunova, Yu. G.; Tsivadze, A. Yu.

    2015-08-01

    The photoconductive, photorefractive and nonlinear optical properties of composites from polyvinylcarbazole or aromatic polyimide containing supramolecular ensembles of (tetra-15-crown-5) - phthalocyaninato gallium, indium, - phthalocyaninateacetato yttrium, - phthalocyaninato ruthenium with axially coordinated pyrazine molecules were investigated at 633, 1030 and 1064nmusing continuous and pulsed lasers. Supramolecular ensembles (SE) were prepared through dissolution of molecular metallophthalocyanines in tetrachloroethane (TCE) and subsequent treatment via three cycles of heating to 90∘C and slow cooling to room temperature. The zscan method in femtosecond and nanosecond regimeswas used for measuring nonlinear optical properties phthalocyaninato indium and yttrium in TCE solutions and polymer films. It was established that effect of heavy metallic atom is basic factor which determines the quantum yield, photorefractive amplification of laser object beam, dielectric susceptibility of third order and nonlinear optical properties of metallophthalocyanines.

  7. Composite multiobjective optimization beamforming based on genetic algorithms

    Institute of Scientific and Technical Information of China (English)

    Shi Jing; Meng Weixiao; Zhang Naitong; Wang Zheng

    2006-01-01

    All thc parameters of beamforming are usually optimized simultaneously in implementing the optimization of antenna array pattern with multiple objectives and parameters by genetic algorithms (GAs).Firstly, this paper analyzes the performance of fitness functions of previous algorithms. It shows that original algorithms make the fitness functions too complex leading to large amount of calculation, and also the selection of the weight of parameters very sensitive due to many parameters optimized simultaneously. This paper proposes a kind of algorithm of composite beamforming, which detaches the antenna array into two parts corresponding to optimization of different objective parameters respectively. New algorithm substitutes the previous complex fitness function with two simpler functions. Both theoretical analysis and simulation results show that this method simplifies the selection of weighting parameters and reduces the complexity of calculation. Furthermore, the algorithm has better performance in lowering side lobe and interferences in comparison with conventional algorithms of beamforming in the case of slightly widening the main lobe.

  8. A composite thermal insulator based on xonotlite and perlite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A low cost thermal insulating material can be produced by compounding an active xonotlite slurry, fired-perlite, HOMO PAN fibers and glass fibers. The maximum service temperature of the product is 800℃; linear shrinkage after 800℃(16 h firing is 0.9%; the cold crushing strength is 1.56 MPa; the flexural strength at ambient temperature is 0.81 MPa; the thermal conductivity at ambient temperature (25℃) is 0.056 and 0.128 W/(m@K) at 800℃. The production cost of such a composite is only 1/3 of that of the normal xonotlite thermal insulators. It can substitute the normal xonotlite thermal insulators on most occasions with a similar cost to that of normal perlite products.

  9. Reliability-Based Design Optimization of a Composite Airframe Component

    Science.gov (United States)

    Patnaik, Surya N.; Pai, Shantaram S.; Coroneos, Rula M.

    2009-01-01

    A stochastic design optimization methodology (SDO) has been developed to design components of an airframe structure that can be made of metallic and composite materials. The design is obtained as a function of the risk level, or reliability, p. The design method treats uncertainties in load, strength, and material properties as distribution functions, which are defined with mean values and standard deviations. A design constraint or a failure mode is specified as a function of reliability p. Solution to stochastic optimization yields the weight of a structure as a function of reliability p. Optimum weight versus reliability p traced out an inverted-S-shaped graph. The center of the inverted-S graph corresponded to 50 percent (p = 0.5) probability of success. A heavy design with weight approaching infinity could be produced for a near-zero rate of failure that corresponds to unity for reliability p (or p = 1). Weight can be reduced to a small value for the most failure-prone design with a reliability that approaches zero (p = 0). Reliability can be changed for different components of an airframe structure. For example, the landing gear can be designed for a very high reliability, whereas it can be reduced to a small extent for a raked wingtip. The SDO capability is obtained by combining three codes: (1) The MSC/Nastran code was the deterministic analysis tool, (2) The fast probabilistic integrator, or the FPI module of the NESSUS software, was the probabilistic calculator, and (3) NASA Glenn Research Center s optimization testbed CometBoards became the optimizer. The SDO capability requires a finite element structural model, a material model, a load model, and a design model. The stochastic optimization concept is illustrated considering an academic example and a real-life raked wingtip structure of the Boeing 767-400 extended range airliner made of metallic and composite materials.

  10. PCR-based detection of composite transposons and translocatable units from oral metagenomic DNA.

    Science.gov (United States)

    Tansirichaiya, Supathep; Mullany, Peter; Roberts, Adam P

    2016-09-01

    A composite transposon is a mobile genetic element consisting of two insertion sequences (ISs) flanking a segment of cargo DNA often containing antibiotic resistance (AR) genes. Composite transposons can move as a discreet unit. There have been recently several reports on a novel mechanism of movement of an IS26-based composite transposon through the formation of a translocatable unit (TU), carrying the internal DNA segment of a composite transposon and one copy of a flanking IS. In this study, we determined the presence of composite transposons and TUs in human oral metagenomic DNA using PCR primers from common IS elements. Analysis of resulting amplicons showed four different IS1216 composite transposons and one IS257 composite transposon in our metagenomic sample. As our PCR strategy would also detect TUs, PCR was carried out to detect circular TUs predicted to originate from these composite transposons. We confirmed the presence of two novel TUs, one containing an experimentally proven antiseptic resistance gene and another containing a putative universal stress response protein (UspA) encoding gene. This is the first report of a PCR strategy to amplify the DNA segment on composite transposons and TUs in metagenomic DNA. This can be used to identify AR genes associated with a variety of mobile genetic elements from metagenomes.

  11. Comparison of the mechanical properties between carbon nanotube and nanocrystalline cellulose polypropylene based nano-composites

    International Nuclear Information System (INIS)

    Highlights: • SWCNT and NCC can effectively improve the mechanical properties of nano-composites. • SWCNT is more effective than NCC to increase modulus and strength. • Longer NCC is more effective to improve the mechanical properties of nano-composites. • It is more economic to use NCC than SWCNT to improve mechanical properties. - Abstract: Using beam and tetrahedron elements to simulate nanocrystalline cellulose (NCC), single wall carbon nanotube (SWCNT) and polypropylene (PP), finite element method (FEM) is used to predict the mechanical properties of nano-composites. The bending, shear and torsion behaviors of nano-composites are especially investigated due to the limited amount of information in the present literature. First, mixed method (MM) and FEM are used to compare the bending stiffness of NCC/PP and SWCNT/PP composites. Second, based on mechanics of materials, the shear moduli of both types of nano-composites are obtained. Finally, fixing the number of fibers and for different volume contents, four NCC lengths are used to determine the mechanical properties of the composites. The bending and shearing performances are also compared between NCC and SWCNT based composites. In all cases, the elastic–plastic analyses are carried out and the stress or strain distributions for specific regions are also investigated. From all the results obtained, an economic analysis shows that NCC is more interesting than SWCNT to reinforce PP

  12. Influence of alkali ion doping on the electrochemical performances of tin-based composite materials

    Science.gov (United States)

    Aboulaich, A.; Conte, D. E.; Olivier-Fourcade, J.; Jordy, C.; Willmann, P.; Jumas, J. C.

    In this paper, we report an investigation of three tin-based composite materials as negative electrodes for lithium-ion batteries. Theses composites were synthesized by solid state reaction from dispersion of micrometric tin into BPO 4, Li-doped BPO 4 (LiBPO) and Na-substituted BPO 4 (NaBPO) matrix, respectively. We have investigated more particularly the influence of the two alkaline ions (Li +, Na +) introduced into the matrix on electrochemical performances. The morphology of powders was observed by SEM and the composition studied by EDX analysis. The conductivity measurements showed that the modified BPO 4 matrixes (Li or Na) exhibit improved conductivity (σ RT = 2 × 10 -11 S cm -1 for NaBPO). A focus of our interest was to relate the nature and structural composition of the composite interface between active tin and inactive matrix to the irreversible capacity in this type of composite materials. The electrochemical analysis shows a decrease of the irreversible capacity for the composite based on modified matrixes (around 150 and 190 mAh g -1 for SnNaBPO and SnLiBPO, respectively) with respect to the reference composite SnBPO (245 mAh g -1).

  13. Influence of alkali ion doping on the electrochemical performances of tin-based composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Aboulaich, A.; Conte, D.E.; Olivier-Fourcade, J.; Jumas, J.C. [Institut Charles Gerhardt-Laboratoire des Agregats, Interfaces et Materiaux pour l' Energie (UMR 5253), Place Eugene Bataillon, 34095 Montpellier Cedex 5 (France); Jordy, C. [SAFT, 111-113 Boulevard Alfred Daney, 33300 Bordeaux Cedex (France); Willmann, P. [Centre National d' Etudes Spatiales, 18 Avenue Edouard Belin, 31401 Toulouse Cedex 9 (France)

    2010-05-15

    In this paper, we report an investigation of three tin-based composite materials as negative electrodes for lithium-ion batteries. Theses composites were synthesized by solid state reaction from dispersion of micrometric tin into BPO{sub 4}, Li-doped BPO{sub 4} (LiBPO) and Na-substituted BPO{sub 4} (NaBPO) matrix, respectively. We have investigated more particularly the influence of the two alkaline ions (Li{sup +}, Na{sup +}) introduced into the matrix on electrochemical performances. The morphology of powders was observed by SEM and the composition studied by EDX analysis. The conductivity measurements showed that the modified BPO{sub 4} matrixes (Li or Na) exhibit improved conductivity ({sigma}{sub RT} = 2 x 10{sup -11} S cm{sup -1} for NaBPO). A focus of our interest was to relate the nature and structural composition of the composite interface between active tin and inactive matrix to the irreversible capacity in this type of composite materials. The electrochemical analysis shows a decrease of the irreversible capacity for the composite based on modified matrixes (around 150 and 190 mAh g{sup -1} for SnNaBPO and SnLiBPO, respectively) with respect to the reference composite SnBPO (245 mAh g{sup -1}). (author)

  14. Microcrystalline-cellulose and polypropylene based composite: A simple, selective and effective material for microwavable packaging.

    Science.gov (United States)

    Ummartyotin, S; Pechyen, C

    2016-05-20

    Cellulose based composite was successfully designed as active packaging with additional feature of microwavable properties. Small amount of cellulose with 10 μm in diameter was integrated into polypropylene matrix. The use of maleic anhydride was employed as coupling agent. Thermal and mechanical properties of cellulose based composite were superior depending on polypropylene matrix. Crystallization temperature and compressive strength were estimated to be 130 °C and 5.5 MPa. The crystal formation and its percentage were therefore estimated to be 50% and it can be predicted on the feasibility of microwavable packaging. Morphological properties of cellulose based composite presented the good distribution and excellent uniformity. It was remarkable to note that cellulose derived from cotton can be prepared as composite with polypropylene matrix. It can be used as packaging for microwave application. PMID:26917383

  15. Estimation of conjugate gamma and gamma-prime compositions in Ni-base superalloys

    Science.gov (United States)

    Dreshfield, R. L.

    1977-01-01

    To control the formation of unwanted phases, superalloy metallurgists have developed methods of estimating the composition of the matrix phase of alloys. That composition is then used to estimate the alloy's propensity toward sigma and other unwanted phase formations upon prolonged exposure to elevated temperatures in service. This paper reviews two approaches for estimating phase composition from the melt composition. One method is based on assigning essentially fixed stoichiometry to precipitating phases and is typified by 'PHACOMP'. The second method uses analytical geometry to interpret phase diagrams and is shown to be applicable to a two-phase region of a six-component Ni-base system. The geometric method is also shown to be applicable to commercial Ni-base superalloys.

  16. Microstructure and properties of titanium nitride and titanium diboride-based composites

    Energy Technology Data Exchange (ETDEWEB)

    Bellosi, A.; Monteverde, F. [CNR-IRTEC, Research Inst. for Ceramics Technology, Faenza (Italy)

    2000-07-01

    Densification behaviour, microstructure and properties of TiN and TiB{sub 2}-based composites were compared to monolithic materials. Improvements in sinterability and properties were obtained with the addition of nickel as sintering aid. In TiB{sub 2}-based composites, the addition of B{sub 4}C as second phase increased strength and toughness of about 22% and 25%, respectively. In TiN-based composites, the addition of TiB{sub 2} as reinforcing phase improved both hardness and strength in comparison to pure TiN ceramic. Sintering behaviour is discussed in terms of starting compositions; mechanical and physical properties are related to microstructural characteristics. (orig.)

  17. Novel mesoporous composites based on natural rubber and hexagonal mesoporous silica: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Nuntang, Sakdinun; Poompradub, Sirilux [Fuels Research Center, Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Butnark, Suchada [PTT Research and Technology Institute, PTT Public Company Limited, Wangnoi, Ayutthaya 13170 (Thailand); Yokoi, Toshiyuki; Tatsumi, Takashi [Division of Catalytic Chemistry, Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ngamcharussrivichai, Chawalit, E-mail: Chawalit.Ng@Chula.ac.th [Fuels Research Center, Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand)

    2014-02-14

    The present study is the first report on the synthesis and characterization of mesoporous composites based on natural rubber (NR) and hexagonal mesoporous silica (HMS). A series of NR/HMS composites were prepared in tetrahydrofuran via an in situ sol–gel process using tetraethylorthosilicate as the silica precursor. The physicochemical properties of the composites were characterized by various techniques. The effects of the gel composition on the structural and textural properties of the NR/HMS composites were investigated. The Fourier-transform infrared spectroscopy (FTIR) and {sup 29}Si magic angle spinning nuclear magnetic resonance ({sup 29}Si MAS NMR) results revealed that the surface silanol groups of NR/HMS composites were covered with NR molecules. The powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) data indicated an expansion of the hexagonal unit cell and channel wall thickness due to the incorporation of NR molecules into the mesoporous structure. NR/HMS composites also possessed nanosized particles (∼79.4 nm) as confirmed by scanning electron microscopy (SEM) and particle size distribution analysis. From N{sub 2} adsorption–desorption measurement, the NR/HMS composites possessed a high BET surface area, large pore volume and narrow pore size distribution. Further, they were enhanced hydrophobicity confirmed by H{sub 2}O adsorption–desorption measurement. In addition, the mechanistic pathway of the NR/HMS composite formation was proposed. - Highlights: • NR molecules were incorporated into hexagonal meso-structure of HMS. • NR/HMS composites exhibited an expanded unit cell and channel wall thickness. • Nanosized NR/HMS composites with a lower particle size range were obtained. • NR/HMS had high surface area, large pore volume and narrow pore size distribution. • NR/HMS composites displayed an enhanced hydrophobicity.

  18. Electromagnetic and Dynamic Mechanical Properties of Epoxy and Vinylester-Based Composites Filled with Graphene Nanoplatelets

    Directory of Open Access Journals (Sweden)

    Fabrizio Marra

    2016-07-01

    Full Text Available Development of epoxy or epoxy-based vinyl ester composites with improved mechanical and electromagnetic properties, filled with carbon-based nanomaterials, is of crucial interest for use in aerospace applications as radar absorbing materials at radio frequency. Numerous studies have highlighted the fact that the effective functional properties of this class of polymer composites are strongly dependent on the production process, which affects the dispersion of the nanofiller in the polymer matrix and the formation of micro-sized aggregations, degrading the final properties of the composite. The assessment of the presence of nanofiller aggregation in a composite through microscopy investigations is quite inefficient in the case of large scale applications, and in general provides local information about the aggregation state of the nanofiller rather than an effective representation of the degradation of the functional properties of the composite due to the presence of the aggregates. In this paper, we investigate the mechanical, electrical, and electromagnetic properties of thermosetting polymer composites filled with graphene nanoplatelets (GNPs. Moreover, we propose a novel approach based on measurements of the dielectric permittivity of the composite in the 8–12 GHz range in order to assess the presence of nanofiller aggregates and to estimate their average size and dimensions.

  19. Addition of silver nanoparticles reduces the wettability of methacrylate and silorane-based composites

    Directory of Open Access Journals (Sweden)

    Shahin Kasraei

    2012-12-01

    Full Text Available Incorporation of silver nanoparticles into composite resins is recommended for their reported antibacterial properties, but this incorporation can affect the wettability of such materials. Therefore, this study evaluated the effect of nano-silver addition to silorane-based and methacrylate-based composites on their contact angle. Nano-silver particles were added to Z250 (methacrylate-based and P90 (silorane-based composites at 0.5% and 1% by weight. The control group had no additions. SEM-EDX analysis was performed to confirm the homogeneity of the nano-silver distribution. Seventy-two composite discs were prepared and standardized to the identical surface roughness values, and then distributed randomly into 6 groups containing 12 samples each (N = 12. Two random samples from each group were observed by atomic force microscopy. Distilled water contact angle measurements were performed for the wettability measurement. Two-way ANOVA, followed by the Tukey-HSD test, with a significance level of 5%, were used for data analysis. It was observed that wettability was significantly different between the composites (p = 0.0001, and that the addition of nano-silver caused a significant reduction in the contact angle (p = 0.0001. Wettability varied depending on the concentration of the nano silver (p = 0.008. Silorane-based composites have a higher contact angle than methacrylate-based composites. Within the limitations of this study, it can be concluded that the addition of 0.5% nano-silver particles to the composites caused a decrease in the contact angle of water.

  20. Combustion wave structure of ADN based composite propellant

    OpenAIRE

    Fujisato, Koji; Habu, Hiroto; Hori, Keiichi; Shibamoto, Hidefumi; Yu, Xiuchao; Miyake, Atsumi

    2013-01-01

    Combustion characteristics of pelletized ammonium dinitramide (ADN) and ADN-based propellants have been studied. Micron-meter-sized particles of Al, Fe2O3, TiO2, NiO, Cu(OH)NO3, Cu and CuO, and nano-meter-sized Al (Alex) and CuO (nanoCuO) were employed as the additives for pelletized ADN. Only nanoCuO and Alex show the remarkable effects, so they are also added to ADN-based propellant. The binder of ADN-based propellant is thermoplastic elastomer (TP), and three kinds of mixtures (TP:ADN = 30...

  1. Physicochemical characterization of three fiber-reinforced epoxide-based composites for dental applications.

    Science.gov (United States)

    Bonon, Anderson J; Weck, Marcus; Bonfante, Estevam A; Coelho, Paulo G

    2016-12-01

    Fiber-reinforced composite (FRC) biomedical materials are in contact with living tissues arising biocompatibility questions regarding their chemical composition. The hazards of materials such as Bisphenol A (BPA), phthalate and other monomers and composites present in FRC have been rationalized due to its potential toxicity since its detection in food, blood, and saliva. This study characterized the physicochemical properties and degradation profiles of three different epoxide-based materials intended for restorative dental applications. Characterization was accomplished by several methods including FTIR, Raman, Brunauer-Emmett-Teller (BET) Analysis, X-ray fluorescence spectroscopy, and degradation experiments. Physicochemical characterization revealed that although materials presented similar chemical composition, variations between them were more largely accounted by the different phase distribution than chemical composition. PMID:27612785

  2. Physicochemical characterization of three fiber-reinforced epoxide-based composites for dental applications.

    Science.gov (United States)

    Bonon, Anderson J; Weck, Marcus; Bonfante, Estevam A; Coelho, Paulo G

    2016-12-01

    Fiber-reinforced composite (FRC) biomedical materials are in contact with living tissues arising biocompatibility questions regarding their chemical composition. The hazards of materials such as Bisphenol A (BPA), phthalate and other monomers and composites present in FRC have been rationalized due to its potential toxicity since its detection in food, blood, and saliva. This study characterized the physicochemical properties and degradation profiles of three different epoxide-based materials intended for restorative dental applications. Characterization was accomplished by several methods including FTIR, Raman, Brunauer-Emmett-Teller (BET) Analysis, X-ray fluorescence spectroscopy, and degradation experiments. Physicochemical characterization revealed that although materials presented similar chemical composition, variations between them were more largely accounted by the different phase distribution than chemical composition.

  3. Mechanical properties of Cu-based composites reinforced by carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Cu-based composites reinforced by 0 % ~25 % (volume fraction) carbon nanotubes were prepared. The fracture behaviors and the rolling properties of the composites and the effects of the volume fraction of the carbon nanotubes were studied. The experimental results show that the fracture toughness of the composites is related to the pulling-out and bridging of the carbon nanotubes in the fracture process. With the volume fraction of the carbon nanotubes increasing, the Vicker' s hardness and the compactness of the composites increase first and then decrease. The peaks of the hardness and the compactness occur at 12 % ~15 % of volume fraction of carbon nanotubes. Some proper ratio of rolling reduction benefits to the comprehensive mechanical properties of the composites.

  4. Synthesis and characterization of composites filtration membranes based on chitosan-poly(ethylene glycol)

    Science.gov (United States)

    Khoerunnisa, Fitri; Hendrawan, Sonjaya, Yaya; Putri, Agnes

    2015-12-01

    We have successfully synthesized chitosan-PEG based composite filtration membranes using solvent evaporation method at composition variation of chitosan and PEG of 2:1 and 3:1. The SEM images showed that synthesized membranes have anisotropic surface morphologies with different pore size and distribution. The range pore size were 0.05-0.30 um and 0.05-0.50 um for ratio of 2:1 and 3:1, respectively. The FTIR spectra confirmed the interaction of chitosan and PEG functional groups in membranes composites which mainly occurred through van der Waal interaction and intermolecular hydrogen bonding. Chitosan-PEG membranes composites (ratio of 3:1) showed the flux (permeability) three times higher than that of 2:1, and rejection efficiency close to 100%. Moreover, these composites membranes exhibited good performance on water purification where the turbidity was notably reduced from 411 to 36 NTU.

  5. Finite element based composite solution for neutron transport problems

    International Nuclear Information System (INIS)

    A finite element treatment for solving neutron transport problems is presented. The employs region-wise discontinuous finite elements for the spatial representation of the neutron angular flux, while spherical harmonics are used for directional dependence. Composite solutions has been obtained by using different orders of angular approximations in different parts of a system. The method has been successfully implemented for one dimensional slab and two dimensional rectangular geometry problems. An overall reduction in the number of nodal coefficients (more than 60% in some cases as compared to conventional schemes) has been achieved without loss of accuracy with better utilization of computational resources. The method also provides an efficient way of handling physically difficult situations such as treatment of voids in duct problems and sharply changing angular flux. It is observed that a great wealth of information about the spatial and directional dependence of the angular flux is obtained much more quickly as compared to Monte Carlo method, where most of the information in restricted to the locality of immediate interest. (author)

  6. A composition algorithm based on crossmodal taste-music correspondences

    Directory of Open Access Journals (Sweden)

    Bruno eMesz

    2012-04-01

    Full Text Available While there is broad consensus about the structural similarities between language and music, comparably less attention has been devoted to semantic correspondences between these two ubiquitous manifestations of human culture. We have investigated the relations between music and a narrow and bounded domain of semantics: the words and concepts referring to taste sensations. In a recent work, we found that taste words were consistently mapped to musical parameters. Bitter is associated with low-pitched and continuous music (legato, salty is characterized by silences between notes (staccato, sour is high pitched, dissonant and fast and sweet is consonant, slow and soft (Mesz2011. Here we extended these ideas, in a synergistic dialog between music and science, investigating whether music can be algorithmically generated from taste-words. We developed and implemented an algorithm that exploits a large corpus of classic and popular songs. New musical pieces were produced by choosing fragments from the corpus and modifying them to minimize their distance to the region in musical space that characterizes each taste. In order to test the capability of the produced music to elicit significant associations with the different tastes, musical pieces were produced and judged by a group of non musicians. Results showed that participants could decode well above chance the taste-word of the composition. We also discuss how our findings can be expressed in a performance bridging music and cognitive science.

  7. A Nanocellulose Polypyrrole Composite Based on Tunicate Cellulose

    Directory of Open Access Journals (Sweden)

    Dawei Zhang

    2013-01-01

    Full Text Available The water-dispersed conductive polypyrrole (PPy was prepared via the in situ oxidative chemical polymerization by using ammonium persulfate (APS as oxidant and tunicate cellulose nanocrystals (T-CNs as a dopant and template for tuning the morphologies of PPy nanoparticles. Highly flexible paper-like materials of PPy/T-CNs nanocomposites with high electrical conductivity values and good mechanical properties were prepared. The structure of nanocomposites of PPy/T-CNs was investigated by using Fourier transform infrared spectroscopy. Scanning electron microscopy and transmission electron microscopy analyses of the composites revealed that PPy consisted of nanoparticles about 2.5 nm in mean size to form a continuous coating covered on the T-CNs. The diameters of the PPy nanoparticles increased from 10 to 100 nm with the increasing pyrrole amount. Moreover, electrical properties of the obtained PPy/T-CNs films were studied using standard four-probe technique and the electrical conductivity could be as high as 10−3 S/cm.

  8. Active vertical tail buffeting suppression based on macro fiber composites

    Science.gov (United States)

    Zou, Chengzhe; Li, Bin; Liang, Li; Wang, Wei

    2016-04-01

    Aerodynamic buffet is unsteady airflow exerting forces onto a surface, which can lead to premature fatigue damage of aircraft vertical tail structures, especially for aircrafts with twin vertical tails at high angles of attack. In this work, Macro Fiber Composite (MFC), which can provide strain actuation, was used as the actuator for the buffet-induced vibration control, and the positioning of the MFC patches was led by the strain energy distribution on the vertical tail. Positive Position Feedback (PPF) control algorithm has been widely used for its robustness and simplicity in practice, and consequently it was developed to suppress the buffet responses of first bending and torsional mode of vertical tail. However, its performance is usually attenuated by the phase contributions from non-collocated sensor/actuator configuration and plants. The phase lag between the input and output signals of the control system was identified experimentally, and the phase compensation was considered in the PPF control algorithm. The simulation results of the amplitude frequency of the closed-loop system showed that the buffet response was alleviated notably around the concerned bandwidth. Then the wind tunnel experiment was conducted to verify the effectiveness of MFC actuators and compensated PPF, and the Root Mean Square (RMS) of the acceleration response was reduced 43.4%, 28.4% and 39.5%, respectively, under three different buffeting conditions.

  9. A composition algorithm based on crossmodal taste-music correspondences

    Science.gov (United States)

    Mesz, Bruno; Sigman, Mariano; Trevisan, Marcos A.

    2012-01-01

    While there is broad consensus about the structural similarities between language and music, comparably less attention has been devoted to semantic correspondences between these two ubiquitous manifestations of human culture. We have investigated the relations between music and a narrow and bounded domain of semantics: the words and concepts referring to taste sensations. In a recent work, we found that taste words were consistently mapped to musical parameters. Bitter is associated with low-pitched and continuous music (legato), salty is characterized by silences between notes (staccato), sour is high pitched, dissonant and fast and sweet is consonant, slow and soft (Mesz et al., 2011). Here we extended these ideas, in a synergistic dialog between music and science, investigating whether music can be algorithmically generated from taste-words. We developed and implemented an algorithm that exploits a large corpus of classic and popular songs. New musical pieces were produced by choosing fragments from the corpus and modifying them to minimize their distance to the region in musical space that characterizes each taste. In order to test the capability of the produced music to elicit significant associations with the different tastes, musical pieces were produced and judged by a group of non-musicians. Results showed that participants could decode well above chance the taste-word of the composition. We also discuss how our findings can be expressed in a performance bridging music and cognitive science. PMID:22557952

  10. Structural, electrical, optical and analytical applications of newly synthesized polyaniline based nickel molybdate composite

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Meraj Alam; Ishrat, Urfi; Dar, Ayaz Mahmood; Ahmad, Anees, E-mail: aneesahmad@yahoo.com

    2015-07-05

    Highlights: • Synthesis of organic–inorganic conducting nano-composite cation-exchanger. • Average particle size was found to be 76 nm. • The nano-composite was found to be selective for Pb(II), Hg(II) and Th(IV) ions. • The nano composite indicated a band gap of about 3.44 eV showing a weak blue shift compared to 3.37 eV. • The binary separations of metal ions are fairly sharp and reproducible with 90–95% recovery. - Abstract: The synthesis of polyaniline based nickel molybdate nano composite cation exchanger was described by sol–gel method and was explored to study the electrical, optical and analytical applications. The nano composite material was characterized by Fourier Transform Infrared (spectrometer), X-ray diffraction, particle size analyzer, scanning electron microscopy and tunneling electron microscopy. The XRD of nano composite material confirmed the semi-crystalline nature while as particle size analysis as well as TEM depicted average particle size of 76 nm. The partition coefficient studies of different metal ions in the composite were performed in demineralised water and sodium dodecyl sulfate surfactant, and it was found to be selective for Pb(II), Hg(II) and Th(IV) ions. To implement the use of polyaniline Ni(II) molybdate nano composite as adsorbent, some important binary separations of metal ions were performed. SEM analysis showed that the nano composite has random non-preferential orientation with no visible cracks and appeared to be composed of dense and loose aggregation of small particles. The UV–vis spectrum of the nano composite indicated a band gap of about 3.44 eV showing a weak blue shift compared to 3.37 eV for the bulk. Due to their optical and electrical properties, nano composite is promising candidate for use as selectivity of different cations.

  11. Investigation on corrosion and wear behaviors of nanoparticles reinforced Ni-based composite alloying layer

    International Nuclear Information System (INIS)

    In order to investigate the role of amorphous SiO2 particles in corrosion and wear resistance of Ni-based metal matrix composite alloying layer, the amorphous nano-SiO2 particles reinforced Ni-based composite alloying layer has been prepared by double glow plasma alloying on AISI 316L stainless steel surface, where Ni/amorphous nano-SiO2 was firstly predeposited by brush plating. The composition and microstructure of the nano-SiO2 particles reinforced Ni-based composite alloying layer were analyzed by using SEM, TEM and XRD. The results indicated that the composite alloying layer consisted of γ-phase and amorphous nano-SiO2 particles, and under alloying temperature (1000 deg. C) condition, the nano-SiO2 particles were uniformly distributed in the alloying layer and still kept the amorphous structure. The corrosion resistance of composite alloying layer was investigated by an electrochemical method in 3.5%NaCl solution. Compared with single alloying layer, the amorphous nano-SiO2 particles slightly decreased the corrosion resistance of the Ni-Cr-Mo-Cu alloying layer. X-ray photoelectron spectroscopy (XPS) revealed that the passive films formed on the composite alloying consisted of Cr2O3, MoO3, SiO2 and metallic Ni and Mo. The dry wear test results showed that the composite alloying layer had excellent friction-reduced property, and the wear weight loss of composite alloying layer was less than 60% of that of Ni-Cr-Mo-Cu alloying layer

  12. Ceramics reinforced metal base composite coatings produced by CO II laser cladding

    Science.gov (United States)

    Yang, Xichen; Wang, Yu; Yang, Nan

    2008-03-01

    Due to the excellent performance in high strength, anti-temperature and anti-wear, ceramics reinforced metal base composite material was used in some important fields of aircraft, aerospace, automobile and defense. The traditional bulk metal base composite materials are the expensive cost, which is limited in its industrial application. Development of laser coating of ceramics reinforced metal base composite is very interesting in economy. This paper is focused on three laser cladding ceramics coatings of SiC particle /Al matrix , Al IIO 3 powder/ Al matrix and WC + Co/mild steel matrix. Powder particle sizes are of 10-60μm. Chemical contents of aluminum matrix are of 3.8-4.0% Cu, 1.2-1.8% Mg, 0.3-0.99% Mn and balance Al. 5KW CO II laser, 5 axes CNC table, JKF-6 type powder feeder and co-axis feeder nozzle are used in laser cladding. Microstructure and performance of laser composite coatings have been respectively examined with OM,SEM and X-ray diffraction. Its results are as follows : Microstructures of 3C-,6H- and 5H- SiC particles + Al + Al 4SiC 4 + Si in SiC/Al composite, hexagonal α-Al IIO 3 + cubic γ-Al IIO 3 + f.c.c Al in Al IIO 3 powder/ Al composite and original WC particles + separated WC particles + eutectic WC + γ-Co solid solution + W IIC particles in WC + Co/steel coatings are respectively recognized. New microstructures of 5H-SiC in SiC/Al composite, cubic γ-Al IIO 3 in Al IIO 3 composite and W IIC in WC + Co/ steel composite by laser cladding have been respectively observed.

  13. Functional chitosan-based grapefruit seed extract composite films for applications in food packaging technology

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Y.M. [Department of Mechanical Engineering, National University of Singapore (Singapore); Lim, S.H.; Tay, B.Y. [Forming Technology Group, Singapore Institute of Manufacturing Technology (Singapore); Lee, M.W. [Food Innovation and Resource Centre, Singapore Polytechnic (Singapore); Thian, E.S., E-mail: mpetes@nus.edu.sg [Department of Mechanical Engineering, National University of Singapore (Singapore)

    2015-09-15

    Highlights: • Chitosan-based grapefruit seed extract (GFSE) films were solution casted. • GFSE was uniformly dispersed within all chitosan film matrices. • All chitosan-based composite films showed remarkable transparency. • Increasing amounts of GFSE incorporated increased the elongation at break of films. • Chitosan-based GFSE composite films inhibited the proliferation of fungal growth. - Abstract: Chitosan-based composite films with different amounts of grapefruit seed extract (GFSE) (0.5, 1.0 and 1.5% v/v) were fabricated via solution casting technique. Experimental results showed that GFSE was uniformly dispersed within all chitosan film matrices. The presence of GFSE made the films more amorphous and tensile strength decreased, while elongation at break values increased as GFSE content increased. Results from the measurement of light transmission revealed that increasing amounts of GFSE (from 0.5 to 1.5% v/v) did not affect transparency of the films. Furthermore, packaging of bread samples with chitosan-based GFSE composite films inhibited the proliferation of fungal growth as compared to control samples. Hence, chitosan-based GFSE composite films have the potential to be a useful material in the area of food technology.

  14. Functional chitosan-based grapefruit seed extract composite films for applications in food packaging technology

    International Nuclear Information System (INIS)

    Highlights: • Chitosan-based grapefruit seed extract (GFSE) films were solution casted. • GFSE was uniformly dispersed within all chitosan film matrices. • All chitosan-based composite films showed remarkable transparency. • Increasing amounts of GFSE incorporated increased the elongation at break of films. • Chitosan-based GFSE composite films inhibited the proliferation of fungal growth. - Abstract: Chitosan-based composite films with different amounts of grapefruit seed extract (GFSE) (0.5, 1.0 and 1.5% v/v) were fabricated via solution casting technique. Experimental results showed that GFSE was uniformly dispersed within all chitosan film matrices. The presence of GFSE made the films more amorphous and tensile strength decreased, while elongation at break values increased as GFSE content increased. Results from the measurement of light transmission revealed that increasing amounts of GFSE (from 0.5 to 1.5% v/v) did not affect transparency of the films. Furthermore, packaging of bread samples with chitosan-based GFSE composite films inhibited the proliferation of fungal growth as compared to control samples. Hence, chitosan-based GFSE composite films have the potential to be a useful material in the area of food technology

  15. Tritium permeation barrier based on self-healing composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Gao Jifeng; Zhang Dan [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Suo Jinping, E-mail: jpsuo@yahoo.com.cn [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2010-12-15

    Pores and cracks in ceramic coatings is one of the most important problems to be solved for the thermally sprayed tritium permeation barriers (TPBs) in fusion reactor. In this work, we developed a self-healing composite coating to address this problem. The coating composed of TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} was deposited on martensitic steels by means of atmospheric plasma spraying (APS). Before and after heat treatment, the morphology and phase of the coating were comparatively investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). In the experiment, NiAl + Al{sub 2}O{sub 3}, mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} and NiAl + TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} films were also fabricated and studied, respectively. The results showed that the TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} coating exhibited the best self-healing ability and good thermal shock resistance among the four samples after heat treatment under normal atmosphere. The SEM images analyzed by Image Pro software indicated that the porosity of the TiC + mixture(TiC/Al{sub 2}O{sub 3}) + Al{sub 2}O{sub 3} coating decreased more than 90% in comparison with the sample before heat treatment. This self-healing coating made by thermal spraying might be a good candidate for tritium permeation barrier in fusion reactors.

  16. Uncertainty analysis based on sensitivity applied to angle-ply composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Conceicao Antonio, Carlos [Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: cantonio@fe.up.pt; Hoffbauer, Luisa N. [Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: lnh@isep.ipp.pt

    2007-10-15

    This article describes a finite element-based formulation for the statistical analysis of the response of stochastic structural composite systems whose material properties are described by random fields. A first-order technique is used to obtain the second-order statistics for the structural response considering means and variances of the displacement and stress fields of plate or shell composite structures. Propagation of uncertainties depends on sensitivities taken as measurement of variation effects. The adjoint variable method is used to obtain the sensitivity matrix. This method is appropriated for composite structures due to the large number of random input parameters. Dominant effects on the stochastic characteristics are studied analyzing the influence of different random parameters. In particular, a study of the anisotropy influence on uncertainties propagation of angle-ply composites is carried out based on the proposed approach.

  17. Mechanochemically synthesized kalsilite based bioactive glass-ceramic composite for dental vaneering

    Science.gov (United States)

    Kumar, Pattem Hemanth; Singh, Vinay Kumar; Kumar, Pradeep

    2015-08-01

    Kalsilite glass-ceramic composites have been prepared by a mechanochemical synthesis process for dental veneering application. The aim of the present study is to prepare bioactive kalsilite composite material for application in tissue attachment and sealing of the marginal gap between fixed prosthesis and tooth. Mechanochemical synthesis is used for the preparation of microfine kalsilite glass-ceramic. Low temperature frit and bioglass have been prepared using the traditional quench method. Thermal, microstructural and bioactive properties of the composite material have been examined. The feasibility of the kalsilite to be coated on the base commercial opaque as well as the bioactive behavior of the coated specimen has been confirmed. This study indicates that the prepared kalsilite-based composites show similar structural, morphological and bioactive behavior to that of commercial VITA VMK95 Dentin 1M2.

  18. RELIABILITY-BASED DESIGN OF COMPOSITES UNDER THE MIXED UNCERTAINTIES AND THE OPTIMIZATION ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    Rui Ge; Jianqiao Chen; Jnnhong Wei

    2008-01-01

    This paper proposed a reliability design model for composite materials under the mixture of random and interval variables. Together with the inverse reliability analysis technique, the sequential single-loop optimization method is applied to the reliability-based design of com-posites. In the sequential single-loop optimization, the optimization and the reliability analysis are decoupled to improve the computational efficiency. As shown in examples, the minimum weight problems under the constraint of structural reliability are solved for laminated composites. The Particle Swarm Optimization (PSO) algorithm is utilized to search for the optimal solutions. The design results indicate that, under the mixture of random and interval variables, the method that combines the sequential single-loop optimization and the PSO algorithm can deal effectively with the reliability-based design of composites.

  19. Evaluation of Johnson-Cook model constants for aluminum based particulate metal matrix composites

    Science.gov (United States)

    Hilfi, H.; Brar, N. S.

    1996-05-01

    High strain rate and high temperature response of three types of aluminum based particulate metal matrix ceramic composites is investigated by performing split Hopkinson pressure bar (SHPB) experiments. The composites are: NGP-2014 (15% SiC), NGT-6061 (15% SiC), and NGU-6061 (15% Al2O3), in which all the reinforcement materials are percentage by volume. Johnson-Cook constitutive model constants are evaluated from the high strain rate/high temperature data and implemented in a two dimensional finite element computer code (EPIC-2D) to simulate the penetration of an ogive nose tungsten projectile (23 grams) at a velocity 1.17 km/sec into the base 6061-T6 aluminum alloy and the composite NGU-6061. The simulated penetrations in the composite and in 6061-T6 aluminum agree with in 2%, in both materials, with the measured values.

  20. Current state of the art of HNF based composite propellants

    NARCIS (Netherlands)

    Ciucci, A.; Frota, O.; Welland, W.H.M.; Heijden, A.E.D.M. van der; Leeming, B.; Bellerby, J.M.; Brotzu, A.

    2004-01-01

    The main activities currently performed for the development of HNF-based propellants are presented. The objectives and approach adopted are described. The results obtained on the HNF decomposition mechanism and on the re- and co-crystallisation of HNF with potential propellant ingredients are presen

  1. Producing multilayer composites based on metal-carbon by vacuum ion-plasma method

    Science.gov (United States)

    Shekhtman, S. R.; Sukhova, N. A.

    2016-07-01

    The possibility of changing the coating properties and perspective of forming a compound having the unique mechanical properties, high hardness and high corrosion resistance is of particular interest to multilayer coatings based on metal-carbon composition. To investigate the mechanisms of formation of coatings and to demonstrate technological possibilities synthesis technology of multilayer composites, the titanium cathode and the silicon-graphite cathode were made. Coatings microhardness analysis showed that in forming the multilayer structure, microhardness increases by 15-20%, and when forming a multilayer composite, microhardness increases by 60-65%.

  2. Luminescent and kinetic properties of the polystyrene composites based on BaF2 nanoparticles

    Science.gov (United States)

    Demkiv, T. M.; Halyatkin, O. O.; Vistovskyy, V. V.; Gektin, A. V.; Voloshinovskii, A. S.

    2016-02-01

    Luminescence-kinetic properties of polystyrene composites based on BaF2 nanoparticles were studied. The electron emission from the nanoparticles due to the photoelectric effect is the main luminescence excitation mechanism in the case of polystyrene composites loaded with small BaF2 nanoparticles (~20 nm). Scintillation pulse of polystyrene composites possesses only fast decay component with the time constant τ~2 ns, and its emission intensity considerably exceeds the one for pure polystyrene scintillator upon the X-ray excitations.

  3. A Ti/Ti-Based-Metallic-Glass Interpenetrating Phase Composite with Remarkable Mutual Reinforcement Effect

    Directory of Open Access Journals (Sweden)

    J. Mu

    2014-01-01

    Full Text Available A Ti/Ti-based-metallic-glass interpenetrating phase composite (IPC was prepared by infiltrating the Ti34.3Zr31.5Ni5.5Cu5Be23.7 melt into the porous Ti skeleton. Porous Ti limits the shear band (SB propagation and promotes the SB multiplication, leading to the improved ductility. Moreover, the interpenetrating phase structure shows a mutual reinforcement effect for both amorphous and crystalline phases, making IPC possess higher strength than that calculated by the models held for the conventional composites. This finding will suggest a new way for preparing composites with high strength and ductility.

  4. Microleakage of silorane- and methacrylate-based class V composite restorations.

    Science.gov (United States)

    Krifka, Stephanie; Federlin, Marianne; Hiller, Karl-Anton; Schmalz, Gottfried

    2012-08-01

    The marginal integrity of class V restorations in a silorane- and a group of methacrylate-based composite resins with varying viscosities was tested in the present study. Different adhesives (OptiBond FL, KerrHawe; AdheSE One, Vivadent; or Silorane System Adhesive, 3M ESPE) were applied to 168 standardized class V cavities. The cavities (n = 12) were filled with a wide range of different viscous composite resins: Filtek Silorane, 3M ESPE; els and els flow, Saremco; Tetric EvoCeram and Tetric EvoFlow, Vivadent; Grandio, Voco; and Ultraseal XT Plus, Ultradent. Microleakage of the restoration was assessed by dye penetration (silver staining) on multiple sections with and without thermocycling and mechanical loading (TCML: 5,000 × 5-55°C; 30 s/cycle; 500,000 × 72.5 N, 1.6 Hz). Data were statistically analyzed with the Mann-Whitney U test and the Error Rates Method (ERM). The silorane-based composite resin yielded the lowest dye penetration after TCML. Microleakage of methacrylate-based composite restorations, in general (ERM), was statistically significantly influenced by the adhesive system, Moreover, dye penetration at enamel margins was significantly lower than dye penetration at dentin margins. The chemical basis of composite resins and adjacent tooth substance seems to strongly influence marginal sealing of class V restorations for methacrylate-based materials. Moreover, the steps of dental adhesives used affected marginal integrity. The silorane-based composite resin evaluated in the present study exhibits the best marginal seal. The three-step adhesive yielded better marginal sealing than the one-step adhesive for methacrylate-based class V composite restorations. PMID:21947906

  5. Study on dynamic services composition of web services based on BPEL

    Science.gov (United States)

    Gao, Jinyue; Huang, Fei; Zhang, Gongxuan

    2013-12-01

    From the core concepts of SOA (Service-Oriented Architecture) ——"Service" starting the service composition is discussed in detail, from the service relationships network modeling, services dynamic composition approach based on Business Process Execution Language BPEL (Business Process Execution Language) is proposed in this paper, meanwhile two concepts of service agent and service quality are described, which achieve the service process dynamic execution.

  6. Charging process of polyurethane based composites under electronic irradiation: Effects of cellulose fiber content

    Science.gov (United States)

    Hadjadj, Aomar; Jbara, Omar; Tara, Ahmed; Gilliot, Mickael; Dellis, Jean-Luc

    2013-09-01

    The study deals with the charging effect of polyurethanes-based composites reinforced with cellulose fibers, under electronic beam irradiation in a scanning electron microscope. The results indicate that the leakage current and the trapped charge as well as the kinetics of charging process significantly change beyond a critical concentration of 10% cellulose fibers. These features are correlated with the cellulose concentration-dependence of the electrical properties, specifically resistivity and capacitance, of the composite.

  7. Colloidal processing of Fe-based metalceramic composites with high content of ceramic reinforcement

    OpenAIRE

    Escribano, J.A.; Ferrari, Begoña; Alvaredo Olmos, Paula; Gordo Odériz, Elena; Sánchez-Herencia, A. J.

    2013-01-01

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases...

  8. Computational estimation of soybean oil adulteration in Nepalese mustard seed oil based on fatty acid composition

    OpenAIRE

    Shrestha, Kshitij; De Meulenaer, Bruno

    2011-01-01

    The experiment was carried out for the computational estimation of soybean oil adulteration in the mustard seed oil using chemometric technique based on fatty acid composition. Principal component analysis and K-mean clustering of fatty acid composition data showed 4 major mustard/rapeseed clusters, two of high erucic and two of low erucic mustard type. Soybean and other possible adulterants made a distinct cluster from them. The methodology for estimation of soybean oil adulteration was deve...

  9. Rubber Composites Based on Polar Elastomers with Incorporated Modified and Unmodified Magnetic Filler

    OpenAIRE

    Kruželák, Ján; Sýkora, Richard; Dosoudil, Rastislav; Hudec, Ivan

    2016-01-01

    Rubber magnetic composites were prepared by incorporation of unmodified and surface modified strontium ferrite into rubber matrices based on NBR and NBR/PVC. Strontium ferrite was dosed to the rubber matrices in concentration scale ranging from 0 to 100 phr. The main goal was to investigate the influence of the type of ferrite on the curing process, physical-mechanical and magnetic properties of composites. The mutual interactions between the filler and rubber matrices were investigated by de...

  10. Smoothed Finite Element and Genetic Algorithm based optimization for Shape Adaptive Composite Marine Propellers

    OpenAIRE

    Herath, Manudha T; Natarajan, Sundararajan; Prusty, B Gangadhara; John, Nigel St

    2013-01-01

    An optimization scheme using the Cell-based Smoothed Finite Element Method (CS-FEM) combined with a Genetic Algorithm (GA) framework is proposed in this paper to design shape adaptive laminated composite marine propellers. The proposed scheme utilise the bend-twist coupling characteristics of the composites to achieve the required performance. An iterative procedure to evaluate the unloaded shape of the propeller blade is proposed, confirming the manufacturing requirements at the initial stag...

  11. INDUS - a composition-based approach for rapid and accurate taxonomic classification of metagenomic sequences

    OpenAIRE

    Mohammed, Monzoorul Haque; Ghosh, Tarini Shankar; Reddy, Rachamalla Maheedhar; Reddy, Chennareddy Venkata Siva Kumar; Singh, Nitin Kumar; Sharmila S Mande

    2011-01-01

    Background Taxonomic classification of metagenomic sequences is the first step in metagenomic analysis. Existing taxonomic classification approaches are of two types, similarity-based and composition-based. Similarity-based approaches, though accurate and specific, are extremely slow. Since, metagenomic projects generate millions of sequences, adopting similarity-based approaches becomes virtually infeasible for research groups having modest computational resources. In this study, we present ...

  12. The preparation of aramid fibres in silicone based composite materials

    OpenAIRE

    L.A. Dobrzański; A. J. Nowak; A. Pusz; M. Górniak

    2011-01-01

    Purpose: The evaluation of modified aramid fibres – Kevlar – as reinforcement in silicon materials used in medicine.Design/methodology/approach: Samples of laminated material based on modified aramid fibres and medical silicone were made by a method of manual formation of laminates that is impregnation of reinforcement with matrix to hardening silicone process using hardening methods connected with heat. Created material was observed on Scanning Electron Microscopy manufactured by Zeiss.Findi...

  13. Nanocellulose-based composites and bioactive agents for food packaging.

    OpenAIRE

    Khan, Avik; Huq, Tanzina; Khan, Ruhul A.; Riedl, Bernard; Lacroix, Monique

    2014-01-01

    International audience Global environmental concern, regarding the use of petroleum-based packaging materials, is encouraging researchers and industries in the search for packaging materials from natural biopolymers. Bioactive packaging is gaining more and more interest not only due to its environment friendly nature but also due to its potential to improve food quality and safety during packaging. Some of the shortcomings of biopolymers, such as weak mechanical and barrier properties can ...

  14. Compositional characterization of clay ceramics and IAEA RM SL-3 by k0-based PGNAA

    International Nuclear Information System (INIS)

    The k0-based prompt gamma-ray neutron activation analysis (k0-based PGNAA) utilizing cold neutron beam facility at Budapest research reactor was applied for compositional characterization of two ancient clay potteries. Accuracy of the method was evaluated by analyzing IAEA RM SL-3. Concentrations of 20 elements at major to trace levels were determined by the PGNAA method used. (author)

  15. A 24-month evaluation of amalgam and resin-based composite restorations

    DEFF Research Database (Denmark)

    McCracken, Michael S; Gordan, Valeria V; Litaker, Mark S;

    2013-01-01

    Knowing which factors influence restoration longevity can help clinicians make sound treatment decisions. The authors analyzed data from The National Dental Practice-Based Research Network to identify predictors of early failures of amalgam and resin-based composite (RBC) restorations....

  16. Content-Based Image Retrieval Using a Composite Color-Shape Approach.

    Science.gov (United States)

    Mehtre, Babu M.; Kankanhalli, Mohan S.; Lee, Wing Foon

    1998-01-01

    Proposes a composite feature measure which combines the shape and color features of an image based on a clustering technique. A similarity measure computes the degree of match between a given pair of images; this technique can be used for content-based image retrieval of images using shape and/or color. Tests the technique on two image databases;…

  17. Effect of Fuel Content and Particle Size Distribution of Oxidiser on Ignition of Metal-Based Pyrotechnic Compositions

    Directory of Open Access Journals (Sweden)

    A. G. Dugam

    1999-07-01

    Full Text Available Influence of boron content in boron-based pyrotechnic composition and particle size distribution of oxidiser, i.e., KNO3 in boron-based pyrotechnic composition is examined by subjecting these to various tests. Study on boron-based pyrotechnic compositions reveals that compositions with 20, 25 and 30 parts by weight of boron are promising igniter compositions wrt their calorimetric values, pressure maximum, ignition delay, etc. However, from sensitivity point of view, the composition with 30 parts of boron is more safe to handle, manufacture and use. From the study of particle size distribution of KNO3 in Mg- based pyrotechnic compositions, it is observed that the composition with wider particle size distribution of oxidiser gives better packing density for their binary miJQ with metal fuel, which in turn gives lower ignition delay and ignition temperature.

  18. Fabrication of magnesium based composites reinforced with carbon nanotubes having superior mechanical properties

    International Nuclear Information System (INIS)

    Research highlights: → Using the IPA based solution, the oxide-free pure Mg/CNTs composite powders could be prepared. → The mechanical strength of the pure Mg composite reinforced with CNTs was not improved though the elongation was enhanced due to the elimination of MgO and less residual strain in the composite. → The mechanical strength of the AZ61Mg alloy composite reinforced with CNTs was improved with maintaining adequate ductility due to the interfacial strengthening of Al2MgC2 ternary carbide. → The CNT addition was not influenced on the microstructure and grain orientations of the AZ61 Mg alloy matrix. - Abstract: Magnesium (Mg) composite reinforced with carbon nanotubes (CNTs) having superior mechanical properties was fabricated using both pure Mg and AZ61 Mg alloy matrix in this study. The composites were produced via powder metallurgy route containing wet process using isopropyl alcohol (IPA) based zwitterionic surfactant solution with unbundled CNTs. The produced composites were evaluated with tensile test and Vickers hardness test and analyzed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectroscopy (EDS) and electron back scattered diffraction (EBSD). As a result, only with AZ61 Mg alloy matrix, tensile strength of the composite was improved. In situ formed Al2MgC2 compounds at the interface between Mg matrix and CNTs effectively reinforced the interfacial bonding and enabled tensile loading transfer from the Mg matrix to nanotubes. Furthermore, it was clarified that the microstructures and grain orientations of the composite matrix were not significantly influenced by CNT addition.

  19. THE USE OF SISAL FIBRE AS REINFORCEMENT IN CEMENT BASED COMPOSITES

    Directory of Open Access Journals (Sweden)

    Romildo Dias Tolêdo Filho

    1999-08-01

    Full Text Available ABSTRACT The inclusion of fibre reinforcement in concrete, mortar and cement paste can enhance many of the engineering properties of the basic materials, such as fracture toughness, flexural strength and resistance to fatigue, impact, thermal shock and spalling. In recent years, a great deal of interest has been created worldwide on the potential applications of natural fibre reinforced, cement based composites. Investigations have been carried out in many countries on various mechanical properties, physical performance and durability of cement based matrices reinforced with naturally occurring fibres including sisal, coconut, jute, bamboo and wood fibres. These fibres have always been considered promising as reinforcement of cement based matrices because of their availability, low cost and low consumption of energy. In this review, the general properties of the composites are described in relation to fibre content, length, strength and stiffness. A chronological development of sisal fibre reinforced, cement based matrices is reported and experimental data are provided to illustrate the performance of sisal fibre reinforced cement composites. A brief description on the use of these composite materials as building products has been included. The influence of sisal fibres on the development of plastic shrinkage in the pre-hardened state, on tensile, compressive and bending strength in the hardened state of mortar mixes is discussed. Creep and drying shrinkage of the composites and the durability of natural fibres in cement based matrices are of particular interest and are also highlighted. The results show that the composites reinforced with sisal fibres are reliable materials to be used in practice for the production of structural elements to be used in rural and civil construction. This material could be a substitute asbestos-cement composite, which is a serious hazard to human and animal health and is prohibited in industrialized countries. The

  20. Pullout behavior of steel fibers from cement-based composites

    DEFF Research Database (Denmark)

    Shannag, M. Jamal; Brincker, Rune; Hansen, Will

    1997-01-01

    fiber reinforcement. The parameters investigated included a specially designed high strength cement based matrix called Densified Small Particles system (DSP), a conventional mortar matrix, fiber embeddment length, and the fiber volume fraction. The mediums from which the fiber was pulled included...... a control mortar mix without fibers, a mortar mix with 3, and 6 percent fibers by volume. The results indicate that: (1) The dense DSP matrix has significantly improved interfacial properties as compared to the conventional mortar matrix. (2) Increasing the fiber embeddment length and the fiber volume...

  1. A State of the Art Review- Methods to Evaluate Electrical Performance of Composite Cross-arms and Composite-based Pylons

    DEFF Research Database (Denmark)

    Wang, Qian; Bak, Claus Leth; Silva, Filipe Miguel Faria da;

    2016-01-01

    A novel uni-body composite pylon has been proposed for 400 kV transmission lines with advantages of compacted size, friendly looking and cost competitiveness. As its configuration is quite different from the traditional lattice pylon, its electrical performance needs in-depth investigation...... and evaluation, for which electrical testing methods are essential. However, as research on composite-based pylons is still in initial stage, leaving international standards and theoretical analysis on this topic very limited, effective testing methods to evaluate the fully composite pylon’s electrical...... performance need to be studied. This paper sums up experience and key advances on testing methods to evaluate electrical performance of composite cross-arms and composite-based pylons. Based on state of the art review, several feasible testing methods that can be used to verify the feasibility of the novel...

  2. Sputtering on the production of tungsten carbide based composites

    OpenAIRE

    Fernandes, Cristina Maria da Silva

    2008-01-01

    O principal objectivo deste trabalho é estudar a viabilidade do revestimento de partículas de carboneto de tungsténio (WC), como etapa alternativa à mistura convencional de componentes. Para tal, revestiram-se pós de WC com aço inoxidável 304 (AISI), por uma técnica de deposição física em fase de vapor, denominada pulverização catódica. O outro objectivo deste trabalho incide na investigação das potencialidades das ligas de Fe/Cr/Ni como ligantes nos compósitos à base de WC....

  3. Properties of Cyanate-Ester-Based Composite Insulation for Magnet Applications

    Science.gov (United States)

    Grandlienard, S. D.; Feucht, S. W.; Fabian, P. E.; Codell, D. E.; Munshi, N. A.

    2006-03-01

    The development of higher-performance composite insulation systems for use in superconducting and fusion magnets has been an ongoing goal for the magnet community for many years. Next Step Option fusion devices will require insulation that can withstand higher temperatures and higher radiation doses, while still requiring performance at cryogenic temperatures. To address this need, Composite Technology Development, Inc. developed cyanate-ester-based composite insulation systems designed to provide improved radiation resistance, higher operating temperatures, and similar cryogenic performance as compared to conventional epoxy-based insulation materials. This paper will discuss the fabrication and performance of cyanate-ester-based composite insulation systems produced using vacuum pressure impregnation, pre-impregnation (i.e., pre-preg), and high-pressure lamination processes. Mechanical test data for tension, compression, and shear properties at 76, 295, and 373 K; dielectric breakdown testing at 76 K; and thermal expansion measurements from 76 to 373 K are presented. Results show that several cyanate-ester-based composite insulation materials exceed the required mechanical performance necessary to perform at the higher operating temperatures expected in future fusion devices.

  4. Thermal diffusivity of hexagonal boron nitride composites based on cross-linked liquid crystalline polyimides.

    Science.gov (United States)

    Shoji, Yu; Higashihara, Tomoya; Tokita, Masatoshi; Morikawa, Junko; Watanabe, Junji; Ueda, Mitsuru

    2013-04-24

    Hexagonal boron nitride (h-BN) composites with the oriented cross-linked liquid crystalline (LC) polyimide have been developed as high thermally conductive materials. Well-dispersed h-BN composite films were obtained, as observed by scanning electron microscopy. The morphology of the composite films was further investigated in detail by the wide-angle X-ray diffraction. The obtained composite films based on the cross-linked LC polyimide showed that the polymer chains vertically aligned in the direction parallel to the films, while those based on the amorphous polyimide showed an isotropic nature. Moreover, the alignment of the cross-linked LC polyimides was maintained, even after increasing the volume fraction of h-BN. This alignment plays an important role in the effective phonon conduction between h-BN and the matrices. Indeed, the thermal diffusivity in the thickness direction of the composite films based on the LC polyimide measured by a temperature wave analysis method was increased to 0.679 mm(2) s(-1) at a 30 vol % h-BN loading, which was higher than that based on the amorphous polyimide. PMID:23506319

  5. Piezoresistive Response Extraction for Smart Cement-based Composites/Sensors

    Institute of Scientific and Technical Information of China (English)

    HAN Baoguo; QIAO Guofu; JIANG Haifeng

    2012-01-01

    A kind of piezoresistive response extraction method for smart cement-based composites/sensors was proposed.Two kinds of typical piezoresistive cement-based composites/sensors were fabricated by respectively adding carbon nanotubes and nickel powders as conductive fillers into cement paste or cement mortar.The variation in measured electrical resistance of such cement-based composites/sensors was explored without loading and under repeated compressive loading and impulsive loading.The experimental results indicate that the measured electrical resistance of piezoresistive cement-based composites/sensors exhibits a two-stage variation trend of fast increase and steady increase with measurement time without loading,and an irreversible increase after loading.This results from polarization caused by ionic conduction in these composites/sensors.After reaching a plateau,the measured electrical resistance can be divided into an electrical resistance part and an electrical capacity part.The piezoresistive responses of electrical resistance part in measured electrical resistance to loading can be extracted by eliminating the linear electrical capacity part in measured electrical resistance.

  6. QoS Requirement Generation and Algorithm Selection for Composite Service Based on Reference Vector

    Institute of Scientific and Technical Information of China (English)

    Bang-Yu Wu; Chi-Hung Chi; Shi-Jie Xu; Ming Gu; Jia-Guang Sun

    2009-01-01

    Under SOA (Service-Oriented Architecture), composite service is formed by aggregating multiple component services together in a given workflow. One key criterion of this research topic is QoS composition. Most work on service composition mainly focuses on the algorithms about how to compose services according to assumed QoS, without considering where the required QoS comes from and the selection of user preferred composition algorithm among those with different computational cost and different selection results. In this paper, we propose to strengthen current service composition mechanism by generation of QoS requirement and its algorithm selection based on the QoS reference vectors which are calculated optimally from the existing individual services' QoS by registry to represent QoS overview about the best QoS,the worst (or most economical) QoS, or the average QoS of all composite services. To implement QoS requirement, which is determined according to QoS overview, this paper introduces two selection algorithms as two kinds of experiment examples,one aiming at the most accurate service selection and the other chasing for trade-off between selection cost and result.Experimental results show our mechanism can help the requester achieve his expected composite service with appropriate QoS requirement and customized selection algorithm.

  7. Wear behaviour of Zr-based in situ bulk metallic glass matrix composites

    Indian Academy of Sciences (India)

    X F WU; G A ZHANG; F F WU

    2016-06-01

    Zr-based bulk metallic glass (BMG) and its in situ BMG matrix composites with diameter of 3 mm were fabricated by conventional Cu-mould casting method and the dry sliding wear behaviour of the BMG and composites was investigated. Compared to the pure BMG, the composites exhibited a markedly improved wear resistance from 10 to 48% due to the existence of various volume fractions of the ductile $\\beta$-Zr dendritic phase embedded in the glassy matrix. The composites showed lower friction coefficient and wear rate than the pure BMG. Meanwhile, the surface wearing of the composite with a proper amount of $\\beta$-Zr dendrites was less severe compared to that of the pure BMG. The worn surface of the composite was covered with mild grooves and some fine wear debris, which exhibited the characteristic of a mild abrasive wear. The improvement of the wear resistance of the composite with the proper amount of $\\beta$-Zr crystalline phase is attributed to the fact that the $\\beta$-Zr crystalline phase distributed in the amorphous matrix has some effective load bearing, plastic deformation and work hardening ability to decrease strain accumulation and the release of strain energy in the glassy matrix, restrict the expanding of shear bands and cracks, and occur plastic deformation homogeneously.

  8. Solar-thermal conversion and thermal energy storage of graphene foam-based composites

    Science.gov (United States)

    Zhang, Lianbin; Li, Renyuan; Tang, Bo; Wang, Peng

    2016-07-01

    Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances the heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a

  9. Warm compacted NbC particulate reinforced iron-base composite(Ⅱ)--Microstructure and properties

    Institute of Scientific and Technical Information of China (English)

    李元元; 肖志瑜; 倪东惠; 夏伟; 陈维平

    2002-01-01

    Effects of different sintering temperature and sintering time on the relative density of the sintered compacts were studied to obtain the optimal sintering parameters for the fabrication of NbC particulate reinforced iron-b ase composite. With optimal sintering temperature of 1 280 ℃ and sintering time of 80 min, wear-resisting, high density NbC particulate reinforced iron-base composites can be obtained using warm compaction powder metallurgy. The microstructure , relative density, mechanical properties and tribological behaviors of the sintered composites were studied. The results indicate that the mechanical properties of the sintered compacts were closely related to the sintered density. The iron -base composite materials with different combinations of mechanical properties and tribological behaviors were developed for different applications. One of the developed composite, which contains 10%NbC, possesses a high strength of 815 Mpa with a remarkable friction and wear behaviors. The other developed composite, which contains 15%NbC, possesses a lesser strength of 515 Mpa but with excellent friction and wear behaviors.

  10. Bio-based polyurethane composite foams with inorganic fillers studied by thermogravimetry

    International Nuclear Information System (INIS)

    Bio-based polyurethane (PU) composite foams filled with various inorganic fillers, such as barium sulfate (BaSO4), calcium carbonate (CaCO3) and talc were prepared using polyols, such as diethylene glycol, triethylene glycol and polyethylene glycol (molecular weight ca. 200) containing molasses and lignin. Reactive hydroxyl groups in plant components and above polyols were used as reaction sites. Morphological observation of fracture surface of composites was carried out by scanning electron microscopy. Thermal properties of bio-based PU composites were examined by thermogravimetry. It was found that the above composites decompose in two stages reflecting decomposition of organic components. Decomposition temperature increased with increasing filler content, when plant components were homogenously mixed with inorganic fillers. Activation energy calculated by Ozawa-Wall-Flynn method was ca. 150 kJ mol-1. The durability of composites was predicted using kinetic data. Calculated values indicate that composites with fillers are more durable than that of those without fillers at a moderate temperature region

  11. Low Cost Fabrication of Silicon Carbide Based Ceramics and Fiber Reinforced Composites

    Science.gov (United States)

    Singh, M.; Levine, S. R.

    1995-01-01

    A low cost processing technique called reaction forming for the fabrication of near-net and complex shaped components of silicon carbide based ceramics and composites is presented. This process consists of the production of a microporous carbon preform and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture with very good control of pore volume and pore size thereby yielding materials with tailorable microstructure and composition. Mechanical properties (elastic modulus, flexural strength, and fracture toughness) of reaction-formed silicon carbide ceramics are presented. This processing approach is suitable for various kinds of reinforcements such as whiskers, particulates, fibers (tows, weaves, and filaments), and 3-D architectures. This approach has also been used to fabricate continuous silicon carbide fiber reinforced ceramic composites (CFCC's) with silicon carbide based matrices. Strong and tough composites with tailorable matrix microstructure and composition have been obtained. Microstructure and thermomechanical properties of a silicon carbide (SCS-6) fiber reinforced reaction-formed silicon carbide matrix composites are discussed.

  12. Intelligent Music Composition using Genetic Algorithm based on Motif Uniform Mutation

    Directory of Open Access Journals (Sweden)

    Faria Nassiri-Mofakham

    2015-03-01

    Full Text Available Nowadays, fields of music and artificial intelligence are closer together through research in both areas. Music composition using artificial intelligence (AI solutions has created a challenging research area. Automatic music composition will not only help researchers understand human’s musical thinking, but also helps composers and musicians improve music theory significantly by using the computing power of computers. In this study, an automatic music composition is presented. The system is implemented by using Markov chain and Lindenmayer systems as well as genetic algorithm. Fitness evaluation of the generated music is achord-based. The evaluations show the fast evolution of the results by genetic algorithm using uniform mutation. Creativity in music composition is beyond the present borders of AI and much work is still ahead in this field.

  13. Compositional dependence of microstructure and tribological properties of plasma sprayed Fe-based metallic glass coatings

    Institute of Scientific and Technical Information of China (English)

    YANG Qin; LI Ran; LIU ZengQian; SHI MinJie; LUO XueKun; ZHANG Tao

    2012-01-01

    Gas-atomized powders of three Fe-based glass-forming alloys were sprayed on mild steel substrates by atmospheric plasma spaying using the same spaying parameters.Microstructures,thermal stabilities and tribological properties of the sprayed coatings were analyzed.The coating performances showed a strong dependence on the intrinsic characters of the compositions,i,e.,glass-forming ability (GFA) and supercooled liquid region (ΔTx).The coatings tended to exhibit higher amorphous phase fraction for the composition with higher GFA and lower porosity for that with larger ΔTx.All the coatings exhibited superior wear resistance compared with the substrate.Higher wear resistance could be obtained in coatings with higher amorphous phase fraction,i.e.higher GFA of the composition.This study has important implications for composition selecting and optimizing in the fabrication of metallic glass coatings.

  14. Current-Voltage Characteristics of the Composites Based on Epoxy Resin and Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Iwona Pełech

    2015-01-01

    Full Text Available Polymer composites based on epoxy resin were prepared. Multiwalled carbon nanotubes synthesized on iron-cobalt catalyst were applied as a filler in a polymer matrix. Chlorine or hydroxyl groups were incorporated on the carbon nanotubes surface via chlorination or chlorination followed by hydroxylation. The effect of functionalized carbon nanotubes on the epoxy resin matrix is discussed in terms of the state of CNTs dispersion in composites as well as electrical properties. For the obtained materials current-voltage characteristics were determined. They had a nonlinear character and were well described by an exponential-type equation. For all the obtained materials the percolation threshold occurred at a concentration of about 1 wt%. At a higher filler concentration >2 wt%, better conductivity was demonstrated by polymer composites with raw carbon nanotubes. At a lower filler concentration <2 wt%, higher values of electrical conductivity were obtained for polymer composites with modified carbon nanotubes.

  15. Influence of carbon fillers nature on the structural and morphological properties of polyurethane-based composites

    Science.gov (United States)

    Melentyev, S. V.; Malinovskaya, T. D.; Pavlov, S. V.

    2016-01-01

    The present paper is devoted to studying structural and morphological properties of the resistive composite materials based on the polyurethane binder. The paper shows the influence of nature, size, shape, concentration of conductive carbon fillers (channel black K-163, graphite element GE-3, colloidal-graphite preparation C-1) and the method of their introduction into the binder to form the electrical conductivity of composites. Experimentally it was found out that a homogeneous composite structure reaches dispersive mixing filler and binder within 120 min. The analysis of the morphological pattern surfaces and chipping resistance materials has demonstrated that composites with colloidal-graphite preparation C-1 are more unimodal with the same concentrations of the investigated fillers.

  16. Numerical modeling of nonlinear deformation of polymer composites based on hyperelastic constitutive law

    Institute of Scientific and Technical Information of China (English)

    Qingsheng YANG; Fang XU

    2009-01-01

    Fiber reinforced polymer (FRP) composites exhibit nonlinear and hyperelastic characteristics under finite deformation. This paper investigates the macroscopic hyperelastic behavior of fiber reinforced polymer compo-sites using a micromechanical model and finite deforma-tion theory based on the hyperelastic constitutive law. The local stress and deformation of a representative volume element are calculated by the nonlinear finite element method. Then, an averaging procedure is used to find the homogenized stress and strain, and the macroscopic stress-strain curves are obtained. Numerical examples are given to demonstrate hyperelastic behavior and deformation of the composites, and the effects of the distribution pattern of fibers are also investigated to model the mechanical behavior of FRP composites.

  17. Structural analysis of hybrid titania-based mesostructured composites.

    Science.gov (United States)

    Boettcher, Shannon W; Bartl, Michael H; Hu, Jerry G; Stucky, Galen D

    2005-07-13

    High-optical-quality titania-based mesostructured films with cubic or 2D-hexagonal symmetry were fabricated by combining trifluoroacetate (TFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) copolymers. The distribution, dynamics, and local environments of the TFA-modified titania, PEO, and PPO components of the hybrid were investigated. IR/Raman spectroscopy, in situ small-angle X-ray scattering, and transmission electron microscopy studies indicate that TFA coordinates the titanium center and forms a stable complex that is subsequently organized by the block copolymer species into ordered mesostructures. Solid-state NMR (19)F-->(1)H cross-polarization, (13)C{(1)H} two-dimensional heteronuclear correlation, and (1)H relaxation techniques were used to determine that PEO is predominantly incorporated within the TFA-modified titania, and that PPO environments encompass both microphase separated regions and interfacial regions composed of mixed PPO and TFA-modified titania. NMR (19)F multiple-quantum spin counting measurements suggest that -CF(3) groups of the trifluoroacetate ligands do not form clusters but instead randomly distribute within the inorganic component of the hybrid. PMID:15998076

  18. Characterization of Vc-Vb Particles Reinforced Fe-Based Composite Coatings Produced by Laser Cladding

    Science.gov (United States)

    Qu, K. L.; Wang, X. H.; Wang, Z. K.

    2016-03-01

    In situ synthesized VC-VB particles reinforced Fe-based composite coatings were produced by laser beam melting mixture of ferrovanadium (Fe-V) alloy, boron carbide (B4C), CaF2 and Fe-based self-melting powders. The results showed that VB particles with black regular and irregular blocky shape and VC with black flower-like shape were uniformly distributed in the coatings. The type, amount, and size of the reinforcements were influenced by the content of FeV40 and B4C powders. Compared to the substrate, the hardness and wear resistance of the composite coatings were greatly improved.

  19. Research on user-aware QoS based Web services composition

    Institute of Scientific and Technical Information of China (English)

    LIU Feng; LEI Zhen-ming

    2009-01-01

    To improve user experience of composite Web services, a user-aware quality of service (QoS) based Web services composition model is proposed. Under such model, a Web services selection method based on quantum genetic algorithm is proposed. This algorithm uses quantum bit encoding, dynamic step-length quantum gate angle adjustment, neighborhood service search and dynamic punishment strategy to expand search scope and speed up convergence. Simulation experiment shows that this algorithm is more efficient than other existing algorithms in Web services selection.

  20. Forced vibration analysis of composite laminates using a discrete layer stress based model

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.J.; Butalia, T.S.; Wolfe, W.E. [Ohio State Univ., Columbus, OH (United States)

    1995-12-31

    Although modern displacement based plate theories are capable of predicting the deflected shape and lower frequencies of a loaded plate with a high degree of precision, their ability to predict stresses, particularly interlaminar stresses, has been poor. A discrete layer stress based theory for composite laminates that assumes a linear distribution of in-plane stresses across each lamina was presented and showed good prediction of interlaminar stresses. The present study extends that work to forced vibration response of a composite plate subjected to a time varying transverse load.

  1. Investigation of the microcrack evolution in a Ti-based bulk metallic glass matrix composite

    Institute of Scientific and Technical Information of China (English)

    Yongsheng Wang; Zhenxi Guo; Rui Ma; Guojian Hao; Yong Zhang; Junpin Lin; Manling Sui

    2014-01-01

    The initiation and evolution behavior of the shear-bands and microcracks in a Ti-based metallic-glass-matrix composite (MGMC) were investigated by using an in-situ tensile test under transmission electron microscopy (TEM). It was found that the plastic deformation of the Ti-based MGMC related with the generation of the plastic deformation zone in crystalline and shear deformation zone in glass phase near the crack tip. The dendrites can suppress the propagation of the shear band effectively. Before the rapid propagation of cracks, the extending of plastic deformation zone and shear deformation zone ahead of crack tip is the main pattern in the composite.

  2. Effect of surface roughness and adhesive system on repair potential of silorane-based resin composite

    OpenAIRE

    Mobarak, Enas H.

    2012-01-01

    This study was performed to evaluate the influence of surface roughness and adhesive system on the repair strength of silorane-based resin composite. Twenty-four substrate discs from silorane-based FiltekP90 were made and stored for 24 h. Half of the discs were roughened against 320 grit SiC paper while the other half was polished against 4000 grit SiC paper. All discs were etched with phosphoric acid. Repair resin composite, FiltekP90 or FiltekZ250, was bonded to the treated surfaces using t...

  3. Composition mediated serration dynamics in Zr-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z.; Qiao, J. W., E-mail: qiaojunwei@gmail.com, E-mail: mwchen@wpi-aimr.tohoku.ac.jp; Wang, B. C.; Xu, B. S. [Laboratory of Applied Physics and Mechanics of Advanced Materials, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Tian, H. [College of Computer Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Sun, B. A. [Center for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon Tong, Kowloon (Hong Kong); Chen, M. W., E-mail: qiaojunwei@gmail.com, E-mail: mwchen@wpi-aimr.tohoku.ac.jp [Laboratory of Applied Physics and Mechanics of Advanced Materials, College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2015-11-16

    The composition mediated serration dynamics in Zr-based bulk metallic glasses (BMGs) is investigated by statistics analyses of the elastic-energy density, and free volumes during shear-banding are beneficial to understand serrated-flow behavior. The amplitude and elastic-energy density display a gradually increasing and then decreasing trend with increasing the content of Zr. It is based on the free-volume theory describing the atomic-level structure of ternary Zr-Cu-Al BMGs. The good agreement between the molecular dynamics simulation and experimental results provides evidence for the variation of free volumes as the elementary mechanism of composition mediated serration dynamics.

  4. Woven hybrid composites: Tensile and flexural properties of oil palm-woven jute fibres based epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Jawaid, M. [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abdul Khalil, H.P.S., E-mail: akhalilhps@gmail.com [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Abu Bakar, A. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2011-06-15

    Highlights: {yields} Woven hybrid composites show good tensile and flexural properties. {yields} Hybridization with 20% woven jute gives rise to sufficient modulus to composites. {yields} Layering pattern affect mechanical properties of hybrid composites. {yields} Statistical analysis shows that there is significant difference between composites. - Abstract: In this research, tensile and flexural performance of tri layer oil palm empty fruit bunches (EFB)/woven jute (Jw) fibre reinforced epoxy hybrid composites subjected to layering pattern has been experimentally investigated. Sandwich composites were fabricated by hand lay-up technique in a mould and cured with 105 deg. C temperatures for 1 h by using hot press. Pure EFB and woven jute composites were also fabricate for comparison purpose. Results showed that tensile and flexural properties of pure EFB composite can be improved by hybridization with woven jute fibre as extreme woven jute fibre mat. It was found that tensile and flexural properties of hybrid composite is higher than that of EFB composite but less than woven jute composite. Statistical analysis of composites done by ANOVA-one way, it showed significant differences between the results obtained. The fracture surface morphology of the tensile samples of the hybrid composites was performed by using scanning electron microscopy.

  5. Woven hybrid composites: Tensile and flexural properties of oil palm-woven jute fibres based epoxy composites

    International Nuclear Information System (INIS)

    Highlights: → Woven hybrid composites show good tensile and flexural properties. → Hybridization with 20% woven jute gives rise to sufficient modulus to composites. → Layering pattern affect mechanical properties of hybrid composites. → Statistical analysis shows that there is significant difference between composites. - Abstract: In this research, tensile and flexural performance of tri layer oil palm empty fruit bunches (EFB)/woven jute (Jw) fibre reinforced epoxy hybrid composites subjected to layering pattern has been experimentally investigated. Sandwich composites were fabricated by hand lay-up technique in a mould and cured with 105 deg. C temperatures for 1 h by using hot press. Pure EFB and woven jute composites were also fabricate for comparison purpose. Results showed that tensile and flexural properties of pure EFB composite can be improved by hybridization with woven jute fibre as extreme woven jute fibre mat. It was found that tensile and flexural properties of hybrid composite is higher than that of EFB composite but less than woven jute composite. Statistical analysis of composites done by ANOVA-one way, it showed significant differences between the results obtained. The fracture surface morphology of the tensile samples of the hybrid composites was performed by using scanning electron microscopy.

  6. Composition and functionality of whole jamun based functional confection.

    Science.gov (United States)

    Sehwag, Sneha; Das, Madhusweta

    2016-06-01

    Whole jamun based functional confection (WJFC) was developed from an optimized blend (through response surface methodology) containing 26.585 % paste of jamun pulp with adhering skin, 2 % jamun seed powder, hydrocolloid mixture (2.289 % agar, 1.890 % pectin and 27.236 % polydextrose), antimicrobials (0.022 % benzoic acid and 0.085 % sorbic acid), and 40 % added water. The confection also contained 0.08 % sucralose, 0.06 % citric acid and 100 mg CaCl2.2H2O/g pectin. The confection was found to be rich in minerals like Ca, Mg, K, Na and P, with prebiotic activity and low glycemic index (48.1). Additionally, WJFC had reduced calorie (1.48 kcal/g) and high dietary fiber content (15.49 ± 0.058 g/100 g (db)). The antioxidant potential measured as DPPH radical scavenging activity and FRAP with different extraction solvents was found to range between 0.26 ± 0.01 and 0.98 ± 0.04 mg BHA/g and 2.57 ± 0.97 and 18.17 ± 1.30 μM Fe(2+)/g, respectively, with highest yield obtained for 50 % aq. ethanolic extract. Moreover, the antioxidant potential was observed to be dose dependent with IC50 values as 9.89 and 2.75 mg (db) against DPPH and superoxide anion radicals, respectively. WJFC was found to suppress α-amylase activity and retard glucose dialysis depicting the antidiabetic effect. PMID:27478212

  7. Selected properties of the aluminium alloy base composites reinforced with intermetallic particles

    Directory of Open Access Journals (Sweden)

    M. Adamiak

    2005-12-01

    Full Text Available Purpose: The main aim of this work is to investigate two types of intermetallics TiAl and Ti3Al as reinforcement and their influence on selected properties and microstructure of aluminium matrix composites.Design/methodology/approach: Aluminium matrix composites were produced employing the atomised aluminium alloy AA6061 as metal matrix, when as reinforcement TiAl and Ti3Al intermetallics particles were used. The powders were cold pressed and then hot extruded. To evaluate the effect of mechanical milling two types of ball mills were used: a low energy (horizontal ball mill and a high energy one (eccentric ball mill. Reinforcement contents for both processes 5, 10, 15 % by weight. To determine hardness Vickers tests were performed. Microstructure observations were made by optical microscopy and scanning electron microscopy SEM.Findings: Based on the examinations carried out one can state that the mechanical milling can produce composites powders with homogenous distribution of reinforcement particles. The mechanically milled and extruded composites show finer and better distribution of reinforcement particles what leads to better mechanical properties of obtained products.Research limitations/implications: In order to evaluate with more detail the possibility of applying these composite materials at practical application, further investigations should be concentrated on the interface reaction of the matrix and reinforcing particles during elevated temperature exposition and their influence on mechanical properties.Practical implications: The composites materials produced by this way have shown significant improvement of the mechanical properties in comparision with matrix materials. Good properties of the composites make them suitable for various technical and industrial applications.Originality/value: It should be stressed that the materials as intermetallic compounds with outstanding mechanical properties and good thermal stability were

  8. Durability-Based Design Properties of Reference Crossply Carbon-Fiber Composite

    Energy Technology Data Exchange (ETDEWEB)

    Corum, J.M.

    2001-04-16

    This report provides recommended durability-based design properties and criteria for a crossply carbon-fiber composite for possible automotive structural applications. Although the composite utilized aerospace-grade carbon-fiber reinforcement, it was made by a rapid-molding process suitable for high-volume automotive use. The material is the first in a planned progression of candidate composites to be characterized as part of an Oak Ridge National Laboratory project entitled Durability of Carbon-Fiber Composites. The overall goal of the project, which is sponsored by the U.S. Department of Energy's Office of Advanced Automotive Technologies and is closely coordinated with the Advanced Composites Consortium, is to develop durability-driven design data and criteria to assure the long-term integrity of carbon-fiber-based composite systems for automotive structural applications. The composite addressed in this report is a ({+-}45{degree})3S crossply consisting of continuous Thornel T300 fibers in a Baydur 420 IMR urethane matrix. This composite is highly anisotropic with two dominant fiber orientations--0/90{degree} and {+-}45{degree}. Properties and models were developed for both orientations. This document is in two parts. Part 1 provides design data and correlations, while Part 2 provides the underlying experimental data and models. The durability issues addressed include the effects of short-time, cyclic, and sustained loadings; temperature; fluid environments; and low-energy impacts (e.g., tool drops and kickups of roadway debris) on deformation, strength, and stiffness. Guidance for design analysis, time-independent and time-dependent allowable stresses, rules for cyclic loadings, and damage-tolerance design guidance are provided.

  9. DNAskew: Statistical Analysis of Base Compositional Asymmetry and Prediction of Replication Boundaries in the Genome Sequences

    Institute of Scientific and Technical Information of China (English)

    Xiang-RuMA; Shao-BoXIAO; Ai-ZhenGUO; Jian-QiangLUE; Huan-ChunCHEN

    2004-01-01

    Sueoka and Lobry declared respectively that, in the absence of bias between the two DNA strands for mutation and selection, the base composition within each strand should be A=T and C=G (this state is called Parity Rule type 2, PR2). However, the genome sequences of many bacteria, vertebrates and viruses showed asymmetries in base composition and gene direction. To determine the relationship of base composition skews with replication orientation, gene function, codon usage biases and phylogenetic evolution,in this paper a program called DNAskew was developed for the statistical analysis of strand asymmetry and codon composition bias in the DNA sequence. In addition, the program can also be used to predict the replication boundaries of genome sequences. The method builds on the fact that there are compositional asymmetries between the leading and the lagging strand for replication. DNAskew was written in Perl script language and implemented on the LINUX operating system. It works quickly with annotated or unannotated sequences in GBFF (GenBank flatfile) or fasta format. The source code is freely available for academic use at http://www.epizooty.com/pub/stat/DNAskew.

  10. The Vibration Based Fatigue Damage Assessment of Steel and Steel Fiber Reinforced Concrete (SFRC Composite Girder

    Directory of Open Access Journals (Sweden)

    Xu Chen

    2015-01-01

    Full Text Available The steel-concrete composite girder has been usually applied in the bridge and building structures, mostly consisting of concrete slab, steel girder, and shear connector. The current fatigue damage assessment for the composite girder is largely based on the strain values and concrete crack features, which is time consuming and not stable. Hence the vibration-based fatigue damage assessment has been considered in this study. In detail, a steel-steel fiber reinforced concrete (SFRC composite girder was tested. The steel fiber reinforced concrete is usually considered for dealing with the concrete cracks in engineering practice. The composite girder was 3.3m long and 0.45m high. The fatigue load and impact excitation were applied on the specimen sequentially. According to the test results, the concrete crack development and global stiffness degradation during the fatigue test were relatively slow due to the favourable performance of SFRC in tension. But on the other hand, the vibration features varied significantly during the fatigue damage development. Generally, it confirmed the feasibility of executing fatigue damage assessment of composite bridge based on vibration method.

  11. Thermal Stability and Flammability of Styrene-Butadiene Rubber-Based (SBR Ceramifiable Composites

    Directory of Open Access Journals (Sweden)

    Rafał Anyszka

    2016-07-01

    Full Text Available Ceramifiable styrene-butadiene (SBR-based composites containing low-softening-point-temperature glassy frit promoting ceramification, precipitated silica, one of four thermally stable refractory fillers (halloysite, calcined kaolin, mica or wollastonite and a sulfur-based curing system were prepared. Kinetics of vulcanization and basic mechanical properties were analyzed and added as Supplementary Materials. Combustibility of the composites was measured by means of cone calorimetry. Their thermal properties were analyzed by means of thermogravimetry and specific heat capacity determination. Activation energy of thermal decomposition was calculated using the Flynn-Wall-Ozawa method. Finally, compression strength of the composites after ceramification was measured and their micromorphology was studied by scanning electron microscopy. The addition of a ceramification-facilitating system resulted in the lowering of combustibility and significant improvement of the thermal stability of the composites. Moreover, the compression strength of the mineral structure formed after ceramification is considerably high. The most promising refractory fillers for SBR-based ceramifiable composites are mica and halloysite.

  12. Semantics-Based Composition of Integrated Cardiomyocyte Models Motivated by Real-World Use Cases.

    Science.gov (United States)

    Neal, Maxwell L; Carlson, Brian E; Thompson, Christopher T; James, Ryan C; Kim, Karam G; Tran, Kenneth; Crampin, Edmund J; Cook, Daniel L; Gennari, John H

    2015-01-01

    Semantics-based model composition is an approach for generating complex biosimulation models from existing components that relies on capturing the biological meaning of model elements in a machine-readable fashion. This approach allows the user to work at the biological rather than computational level of abstraction and helps minimize the amount of manual effort required for model composition. To support this compositional approach, we have developed the SemGen software, and here report on SemGen's semantics-based merging capabilities using real-world modeling use cases. We successfully reproduced a large, manually-encoded, multi-model merge: the "Pandit-Hinch-Niederer" (PHN) cardiomyocyte excitation-contraction model, previously developed using CellML. We describe our approach for annotating the three component models used in the PHN composition and for merging them at the biological level of abstraction within SemGen. We demonstrate that we were able to reproduce the original PHN model results in a semi-automated, semantics-based fashion and also rapidly generate a second, novel cardiomyocyte model composed using an alternative, independently-developed tension generation component. We discuss the time-saving features of our compositional approach in the context of these merging exercises, the limitations we encountered, and potential solutions for enhancing the approach.

  13. Frequency dependence of the self-heating effect in polymer-based composites

    Directory of Open Access Journals (Sweden)

    K. Holeczek

    2010-07-01

    Full Text Available Purpose: The self-heating effect caused by viscous energy dissipation in polymer-based composite structures subjected to harmonic loads is considered to have a great influence on the residual life of the component. The purpose of the conducted investigations is the determination of the dynamic mechanical behaviour of a polymer-based composite material under different excitation frequencies and temperatures.Design/methodology/approach: The dynamic mechanical analysis was employed for measurements of temperature and frequency dependence of the complex rigidity parameters. Obtained loss rigidity curves for different load frequencies enable the determination of the glass-transition temperatures and finally frequency-dependence of the loss rigidity determined on the basis of the kinetic molecular theory and Williams-Landel-Ferry (WLF hypothesis.Findings: The dependency between glass-transition temperature and excitation frequency has been investigated. The activation energy of the phase transition as well as the temperature dependence of the shift factor was calculated. The glass-transition temperature and constants of WLF equation enable the determination of temperature and frequency dependence of the loss rigidity according to the time-temperature superposition principle.Research limitations/implications: The ranges of temperatures were limited to 30-150 °C and excitation frequencies to 1-200 Hz, the behaviour of the composite material outside these ranges can be estimated based on the theoretical assumptions only. Obtained dependencies are correct only for linearly viscoelastic materials.Practical implications: Obtained dependencies can be useful for estimation of the mechanical and thermal degradation of polymer-based composites and can be subsequently applied for the determination of fatigue, crack growth and residual life of composite structures.Originality/value: The determination of temperature and frequency dependence of the loss rigidity

  14. Adaptation of two different calcium hydroxide bases under a composite restoration.

    Science.gov (United States)

    Papadakou, M; Barnes, I E; Wassell, R W; McCabe, J F

    1990-10-01

    A preliminary scanning electron microscope (SEM) study was carried out to investigate how the adaptation of two calcium hydroxide bases (one chemically cured, one light cured) was affected by the polymerization contraction of a supervening light-cured composite resin restoration. Occlusal cavities were prepared in 40 sound extracted human premolars, divided into two equal groups. In the first group a chemically cured calcium hydroxide (Dycal, De Trey Dentsply, Konstanz, FRG) was placed as a base. In the second group a new light-cured calcium hydroxide product (Prisma VLC Dycal, De Trey Dentsply) was used. The restorations were completed with an acid-etched, incrementally placed composite resin. The specimens were sectioned vertically and debrided. A replica was made of each half-tooth. The interfaces between composite resin/base and base/dentine were viewed and photographed in the SEM. The marginal adaptation at these two interfaces was classified into three categories according to the extent of the gaps that were observed. Prisma VLC Dycal base was found to be pulled away from the dentine floor of the cavity as a result of an apparent adhesion to the composite resin during polymerization contraction. Dycal was better adapted to the cavity floor than Prisma VLC Dycal. Disorganization of the resin-bonded Prisma VLC Dycal was minimal even after acid etching the enamel, sectioning and ultrasonic debridement. Dycal appeared to be more friable, and occasionally exhibited marked disorganization as a result of these procedures.

  15. Preparation and Photocatalytic Property of TiO2/Diatomite-Based Porous Ceramics Composite Materials

    Directory of Open Access Journals (Sweden)

    Shuilin Zheng

    2012-01-01

    Full Text Available The diatomite-based porous ceramics was made by low-temperature sintering. Then the nano-TiO2/diatomite-based porous ceramics composite materials were prepared by hydrolysis deposition method with titanium tetrachloride as the precursor of TiO2 and diatomite-based porous as the supporting body of the nano-TiO2. The structure and microscopic appearance of nano-TiO2/diatomite-based porous ceramics composite materials was characterized by XRD and SEM. The photocatalytic property of the composite was investigated by the degradation of malachite green. Results showed that, after calcination at 550°C, TiO2 thin film loaded on the diatomite-based porous ceramics is anatase TiO2 and average grain size of TiO2 is about 10 nm. The degradation ratio of the composite for 5 mg/L malachite green solution reached 86.2% after irradiation for 6 h under ultraviolet.

  16. Topological and thermal properties of polypropylene composites based on oil palm biomass

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, A. H., E-mail: aamir.bhat@petronas.com.my, E-mail: anie-yal88@yahoo.com; Dasan, Y. K., E-mail: aamir.bhat@petronas.com.my, E-mail: anie-yal88@yahoo.com [Department of Fundamental and Applied Sciences, Universiti Teknologi Petronas, 31750 Perak (Malaysia)

    2014-10-24

    Roughness on pristine and polymer composite surfaces is of enormous practical importance for polymer applications. This study deals with the use of varying quantity of oil palm ash as a nanofiller in a polypropylene based matrix. The oil palm ash sample was preprocessed to break the particles into small diameter by using ultra sonication before using microfluidizer for further deduction in size and homogenization. The oil palm ash was made to undergo many passes through the microfluidizer for fine distribution of particles. Polypropylene based composites containing different loading percentage oil palm ash was granulated by twin screw extruder and then injection molded. The surface morphology of the OPA passed through microfluidizer was analyzed by Tapping Mode - Atomic Force Microscopy (TMAFM). Thermal analysis results showed an increase in the activation energy values. The thermal stability of the composite samples showed improvement as compared to the virgin polymer as corroborated by the on-set degradation temperatures and the temperatures at which 50% degradation occurred.

  17. Prognostic for hydraulic pump based upon DCT-composite spectrum and the modified echo state network.

    Science.gov (United States)

    Sun, Jian; Li, Hongru; Xu, Baohua

    2016-01-01

    Prognostic is a key step of the condition-based maintenance (CBM). In order to improve the predicting performance, a novel method for prognostic for the hydraulic pump is proposed in this paper. Based on the improvement of the traditional composite spectrum, the DCT-composite spectrum (DCS) fusion algorithm is initially presented to make fusion of multi-channel vibration signals. The DCS composite spectrum entropy is extracted as the feature. Furthermore, the modified echo state networks (ESN) model is established for prognostic using the extracted feature. The reservoir is updated and the elements of the neighboring matrix are redefined for improving predicting accuracy. Analysis of the application in the hydraulic pump degradation experiment demonstrates that the proposed algorithm is feasible and is meaningful for CBM. PMID:27547667

  18. Prognostic for hydraulic pump based upon DCT-composite spectrum and the modified echo state network.

    Science.gov (United States)

    Sun, Jian; Li, Hongru; Xu, Baohua

    2016-01-01

    Prognostic is a key step of the condition-based maintenance (CBM). In order to improve the predicting performance, a novel method for prognostic for the hydraulic pump is proposed in this paper. Based on the improvement of the traditional composite spectrum, the DCT-composite spectrum (DCS) fusion algorithm is initially presented to make fusion of multi-channel vibration signals. The DCS composite spectrum entropy is extracted as the feature. Furthermore, the modified echo state networks (ESN) model is established for prognostic using the extracted feature. The reservoir is updated and the elements of the neighboring matrix are redefined for improving predicting accuracy. Analysis of the application in the hydraulic pump degradation experiment demonstrates that the proposed algorithm is feasible and is meaningful for CBM.

  19. Topological and thermal properties of polypropylene composites based on oil palm biomass

    International Nuclear Information System (INIS)

    Roughness on pristine and polymer composite surfaces is of enormous practical importance for polymer applications. This study deals with the use of varying quantity of oil palm ash as a nanofiller in a polypropylene based matrix. The oil palm ash sample was preprocessed to break the particles into small diameter by using ultra sonication before using microfluidizer for further deduction in size and homogenization. The oil palm ash was made to undergo many passes through the microfluidizer for fine distribution of particles. Polypropylene based composites containing different loading percentage oil palm ash was granulated by twin screw extruder and then injection molded. The surface morphology of the OPA passed through microfluidizer was analyzed by Tapping Mode - Atomic Force Microscopy (TMAFM). Thermal analysis results showed an increase in the activation energy values. The thermal stability of the composite samples showed improvement as compared to the virgin polymer as corroborated by the on-set degradation temperatures and the temperatures at which 50% degradation occurred

  20. Colloidal processing of Fe-based metal ceramic composites with high content of ceramic reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Escribano, J. A.; Ferrari, B.; Alvaredo, P.; Gordo, E.; Sanchez-Herencia, A. J.

    2013-07-01

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition. (Author)

  1. Colloidal processing of Fe-based metal ceramic composites with high content of ceramic reinforcement

    International Nuclear Information System (INIS)

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition. (Author)

  2. A State of the Art Review- Methods to Evaluate Electrical Performance of Composite Cross-arms and Composite-based Pylons

    DEFF Research Database (Denmark)

    Wang, Qian; Bak, Claus Leth; Silva, Filipe Miguel Faria da;

    2016-01-01

    performance need to be studied. This paper sums up experience and key advances on testing methods to evaluate electrical performance of composite cross-arms and composite-based pylons. Based on state of the art review, several feasible testing methods that can be used to verify the feasibility of the novel......A novel uni-body composite pylon has been proposed for 400 kV transmission lines with advantages of compacted size, friendly looking and cost competitiveness. As its configuration is quite different from the traditional lattice pylon, its electrical performance needs in-depth investigation...

  3. Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells

    Science.gov (United States)

    Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

    2016-03-01

    We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution

  4. Sensor-Based Vibration Signal Feature Extraction Using an Improved Composite Dictionary Matching Pursuit Algorithm

    Directory of Open Access Journals (Sweden)

    Lingli Cui

    2014-09-01

    Full Text Available This paper presents a new method for a composite dictionary matching pursuit algorithm, which is applied to vibration sensor signal feature extraction and fault diagnosis of a gearbox. Three advantages are highlighted in the new method. First, the composite dictionary in the algorithm has been changed from multi-atom matching to single-atom matching. Compared to non-composite dictionary single-atom matching, the original composite dictionary multi-atom matching pursuit (CD-MaMP algorithm can achieve noise reduction in the reconstruction stage, but it cannot dramatically reduce the computational cost and improve the efficiency in the decomposition stage. Therefore, the optimized composite dictionary single-atom matching algorithm (CD-SaMP is proposed. Second, the termination condition of iteration based on the attenuation coefficient is put forward to improve the sparsity and efficiency of the algorithm, which adjusts the parameters of the termination condition constantly in the process of decomposition to avoid noise. Third, composite dictionaries are enriched with the modulation dictionary, which is one of the important structural characteristics of gear fault signals. Meanwhile, the termination condition of iteration settings, sub-feature dictionary selections and operation efficiency between CD-MaMP and CD-SaMP are discussed, aiming at gear simulation vibration signals with noise. The simulation sensor-based vibration signal results show that the termination condition of iteration based on the attenuation coefficient enhances decomposition sparsity greatly and achieves a good effect of noise reduction. Furthermore, the modulation dictionary achieves a better matching effect compared to the Fourier dictionary, and CD-SaMP has a great advantage of sparsity and efficiency compared with the CD-MaMP. The sensor-based vibration signals measured from practical engineering gearbox analyses have further shown that the CD-SaMP decomposition and

  5. A systematic composite service design modeling method using graph-based theory.

    Science.gov (United States)

    Elhag, Arafat Abdulgader Mohammed; Mohamad, Radziah; Aziz, Muhammad Waqar; Zeshan, Furkh

    2015-01-01

    The composite service design modeling is an essential process of the service-oriented software development life cycle, where the candidate services, composite services, operations and their dependencies are required to be identified and specified before their design. However, a systematic service-oriented design modeling method for composite services is still in its infancy as most of the existing approaches provide the modeling of atomic services only. For these reasons, a new method (ComSDM) is proposed in this work for modeling the concept of service-oriented design to increase the reusability and decrease the complexity of system while keeping the service composition considerations in mind. Furthermore, the ComSDM method provides the mathematical representation of the components of service-oriented design using the graph-based theoryto facilitate the design quality measurement. To demonstrate that the ComSDM method is also suitable for composite service design modeling of distributed embedded real-time systems along with enterprise software development, it is implemented in the case study of a smart home. The results of the case study not only check the applicability of ComSDM, but can also be used to validate the complexity and reusability of ComSDM. This also guides the future research towards the design quality measurement such as using the ComSDM method to measure the quality of composite service design in service-oriented software system.

  6. Solar-thermal conversion and thermal energy storage of graphene foam-based composite

    KAUST Repository

    Zhang, Lianbin

    2016-07-11

    Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.

  7. A Model of the Fatigue Life Distribution of Composite Laminates Based on Their Static Strength Distribution

    Institute of Scientific and Technical Information of China (English)

    Wu Fuqiang; Yao Weixing

    2008-01-01

    The reasons of the static strength dispersion and the fatigue life dispersion of composite laminates are analyzed in this article.It is concluded that the inner original defects,which derived from the manufacturing process of composite laminates,are the common and major reason of causing the random distributions of the static strength and the fatigue life.And there is a correlative relation between the two distributions.With the study of statistical relationship between the fatigue loading and the fatigue life in the uniform confidence level and the same survival rate S-N curves of material,the relationship between the static strength distribution and the fatigue life distribution through a material S-N curve model has been obtained.And then the model which is used to describe the distributions of fatigue life of composites,based on their distributions of static strength,is set up.This model reasonably reflects the effects of the inner original defects on the static strength dispersion and on the fatigue life dispersion of composite laminates.The experimental data of three kinds of composite laminates are employed to verify this model,and the results show that this model can predict the random distributions of fatigue life for composites under any fatigue loads fairly well.

  8. Dual-carbon enhanced silicon-based composite as superior anode material for lithium ion batteries

    Science.gov (United States)

    Wang, Jie; Liu, Dai-Huo; Wang, Ying-Ying; Hou, Bao-Hua; Zhang, Jing-Ping; Wang, Rong-Shun; Wu, Xing-Long

    2016-03-01

    Dual-carbon enhanced Si-based composite (Si/C/G) has been prepared via employing the widely distributed, low-cost and environmentally friendly Diatomite mineral as silicon raw material. The preparation processes are very simple, non-toxic and easy to scale up. Electrochemical tests as anode material for lithium ion batteries (LIBs) demonstrate that this Si/C/G composite exhibits much improved Li-storage properties in terms of superior high-rate capabilities and excellent cycle stability compared to the pristine Si material as well as both single-carbon modified composites. Specifically for the Si/C/G composite, it can still deliver a high specific capacity of about 470 mAh g-1 at an ultrahigh current density of 5 A g-1, and exhibit a high capacity of 938 mAh g-1 at 0.1 A g-1 with excellent capacity retention in the following 300 cycles. The significantly enhanced Li-storage properties should be attributed to the co-existence of both highly conductive graphite and amorphous carbon in the Si/C/G composite. While the former can enhance the electrical conductivity of the obtained composite, the latter acts as the adhesives to connect the porous Si particulates and conductive graphite flakes to form robust and stable conductive network.

  9. Effect of silorane-based adhesive system on bond strength between composite and dentin substrate

    Directory of Open Access Journals (Sweden)

    Jefferson Ricardo Pereira

    2015-01-01

    Full Text Available Context: The complexities of the oral environment, the dentin substrate, and the different bond and composite resin systems represent a challenge to the maintenance of reasonable bond between the composite resin and the tooth structure. Aims: To evaluate the effect of the adhesive system on bond strength between silorane-based composite resin and dentin. Materials and Methods: Fourteen human molars extracted were selected and vertically cut into 3 dentin fragments, randomly divided among the experimental groups and restored with Z250 and P90 composite resin using different adhesive protocols (Adper Single Bond 2, Silorano primer, Adper SE Plus, and Scotchbond Multiuse. Two composite resin cylinders were built up on each dentin surface (n = 10 and subjected to a micro-shear bond strength test. Statistical Analysis Used: Kruskal-Wallis one-way analysis of variance and Tukey test (P = 0.05. Results: According to the results, Kruskal-Wallis test evidenced at least one statistical significant difference (P = 0.001. The Tukey test showed statistically significant differences among the group (P < 0.05. Group PSM8 (P90 + SM showed statically significant higher results when compared with groups PSP4 (P90 + SP, PSB2 (P90 + SB, and ZSE5 (Z250 + SE. Conclusion: The results evidenced that the monomer of the adhesive system has an effect on bond strength between the composite resin and dentin.

  10. Tribological properties of Al 7075 alloy based composites strengthened with Al2O3 fibres

    Directory of Open Access Journals (Sweden)

    K. Naplocha

    2011-04-01

    Full Text Available Wear resistance of 7075 aluminium alloy based composite materials reinforced with Al2O3 Saffil fibres was investigated. The measurementsof wear were performed applying the pin-on-disc method at dry friction conditions with the gray iron counterpart. The effects ofpressure of composite samples on the counterpart made of gray iron and the orientation of fibers in relation to the friction surface on wear rate were determined. The materials were produced by squeeze casting method where 80-90% porous ceramic preform were infiltrated.After T6 heat treatment hardness increased about 50-60% both for unreinforced alloy and composites containing strengthening Saffilfibres. Wear resistance of composite materials in relation to the unreinforced 7075 alloy was slightly worse at lower pressure of 0.8 MPa. Under higher pressure of 1.2 MPa wear resistance of unreinforced 7075 alloy was even better whereas no effect of orientation of fibers on wear in composite materials was observed. Additionally, significant wear of counterface in the presence of debris with fragmented Al2O3 fibres as abrasives was observed. Wear resistance improvement of composite materials was obtained when with alumina Saffil fibres Carbon C fibres in the preforms were applied.

  11. Additive Manufacturing of Reactive In Situ Zr Based Ultra-High Temperature Ceramic Composites

    Science.gov (United States)

    Sahasrabudhe, Himanshu; Bandyopadhyay, Amit

    2016-03-01

    Reactive in situ multi-material additive manufacturing of ZrB2-based ultra-high-temperature ceramics in a Zr metal matrix was demonstrated using LENS™. Sound metallurgical bonding was achieved between the Zr metal and Zr-BN composites with Ti6Al4V substrate. Though the feedstock Zr power had α phase, LENS™ processing of the Zr powder and Zr-BN premix powder mixture led to the formation of some β phase of Zr. Microstructure of the Zr-BN composite showed primary grains of zirconium diboride phase in zirconium metal matrix. The presence of ZrB2 ceramic phase was confirmed by X-ray diffraction (XRD) analysis. Hardness of pure Zr was measured as 280 ± 12 HV and, by increasing the BN content in the feedstock, the hardness was found to increase. In Zr-5%BN composite, the hardness was 421 ± 10 HV and the same for Zr-10%BN composite was 562 ± 10 HV. It is envisioned that such multi-materials additive manufacturing will enable products in the future that cannot be manufactured using traditional approaches particularly in the areas of high-temperature metal-ceramic composites with compositional and functional gradation.

  12. Solar-thermal conversion and thermal energy storage of graphene foam-based composites.

    Science.gov (United States)

    Zhang, Lianbin; Li, Renyuan; Tang, Bo; Wang, Peng

    2016-08-14

    Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances the heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy.

  13. The study of mechanical properties of pineapple leaf fibre reinforced tapioca based bioplastic resin composite

    Directory of Open Access Journals (Sweden)

    Mathivanan D.

    2016-01-01

    Full Text Available Natural fibre reinforced composite has brought the material engineering to a high new level of research. Natural fibres are compatible with matrices like polypropylene and can be used as reinforcement material to reduce the composition of plastic in a material. Natural fibres such as kenaf, pineapple leaf, and coir already found its importance in reducing the dependence of petroleum based products. However the biodegradability of the product at the end of the intended lifespan is still questionable. This has led many researches to look for a suitable replacement for synthetic fibres and achieve better adhesion between fibre and matrix. In this study, fiber and matrix which are hydrophilic in nature was used and the mixture was extruded and hot compressed to acquire better mechanical properties. The specimens were fabricated and tested according to ASTM D638. The 30% composition illustrates the best average modulus value among other composition and from this result it can be concluded that the increase of PALF fibre in TBR composite increases the modulus strength of the composite.

  14. Thermally conductive polyamide 6/carbon filler composites based on a hybrid filler system

    Science.gov (United States)

    Ha, Sung Min; Kwon, O. Hwan; Gyeong Oh, Yu; Kim, Yong Seok; Lee, Sung-Goo; Won, Jong Chan; Cho, Kwang Soo; Gak Kim, Byoung; Yoo, Youngjae

    2015-12-01

    We explored the use of a hybrid filler consisting of graphite nanoplatelets (GNPs) and single walled carbon nanotubes (SWCNTs) in a polyamide 6 (PA 6) matrix. The composites containing PA 6, powdered GNP, and SWCNT were melt-processed and the effect of filler content in the single filler and hybrid filler systems on the thermal conductivity of the composites was examined. The thermal diffusivities of the composites were measured by the standard laser flash method. Composites containing the hybrid filler system showed enhanced thermal conductivity with values as high as 8.8 W (m · K)-1, which is a 35-fold increase compared to the thermal conductivity of pure PA 6. Thermographic images of heat conduction and heat release behaviors were consistent with the thermal conductivity results, and showed rapid temperature jumps and drops, respectively, for the composites. A composite model based on the Lewis-Nielsen theory was developed to treat GNP and SWCNT as two separate types of fillers. Two approaches, the additive and multiplicative approaches, give rather good quantitative agreement between the predicted values of thermal conductivity and those measured experimentally.

  15. Composite hydrogel based on surface modified mesoporous silica and poly[(2-acryloyloxy)ethyl trimethylammonium chloride

    Energy Technology Data Exchange (ETDEWEB)

    Torres, Cecilia C. [Department of Organic Chemistry, Faculty of Chemical Science, University of Concepción (Chile); Urbano, Bruno F., E-mail: burbano@udec.cl [Department of Polymer Chemistry, Faculty of Chemical Science, University of Concepción (Chile); Campos, Cristian H. [Department of Organic Chemistry, Faculty of Chemical Science, University of Concepción (Chile); Rivas, Bernabé L. [Department of Polymer Chemistry, Faculty of Chemical Science, University of Concepción (Chile); Reyes, Patricio [Department of Physical Chemistry, Faculty of Chemical Science, University of Concepción (Chile)

    2015-02-15

    This work focused on the synthesis, characterization and water absorbency of a composite hydrogel based on poly[(2-acryloyloxy)ethyl trimethylammonium chloride] and mesoporous silica, MCM-41. The MCM-41 was synthesized and later surface functionalized with triethoxyvinylsilane (VTES) and 3-trimethoxysilylpropylmethacrylate (TMSPM) by a post-grafting procedure. The composite hydrogels were obtained by in-situ polymerization using a mixture of monomer, crosslinker and initiator in the presence of functionalized MCM-41. Diverse characterization techniques were used at the different stages of synthesis, namely, FT-IR, TEM, SEM, DRX, {sup 29}Si and {sup 13}C solid state NMR, and N{sub 2} adsorption isotherms at 77 K. Finally, the water uptake performance of the composites was tested as a function of time, mesoporous silica loading and coupling agent used at the functionalization. The composites using non-functionalized MCM-41 reached the highest water uptake, whereas those composite with MCM-41 TMSPM exhibited the lowest sorption. - Highlights: • Hydrophilic crosslinked polymer-mesoporous silica was obtained. • Mesoporous silica MCM-41 was synthesized and functionalized with organosilane. • Functionalization of MCM-41 affects the water uptake of composite. • Mesoporous silica is covalently bound to the polymer acting as crosslinked point.

  16. Solar-thermal conversion and thermal energy storage of graphene foam-based composites.

    Science.gov (United States)

    Zhang, Lianbin; Li, Renyuan; Tang, Bo; Wang, Peng

    2016-08-14

    Among various utilizations of solar energy, solar-thermal conversion has recently gained renewed research interest due to its extremely high energy efficiency. However, one limiting factor common to all solar-based energy conversion technologies is the intermittent nature of solar irradiation, which makes them unable to stand-alone to satisfy the continuous energy need. Herein, we report a three-dimensional (3D) graphene foam and phase change material (PCM) composite for the seamlessly combined solar-thermal conversion and thermal storage for sustained energy release. The composite is obtained by infiltrating the 3D graphene foam with a commonly used PCM, paraffin wax. The high macroporosity and low density of the graphene foam allow for high weight fraction of the PCM to be incorporated, which enhances the heat storage capacity of the composite. The interconnected graphene sheets in the composite provide (1) the solar-thermal conversion capability, (2) high thermal conductivity and (3) form stability of the composite. Under light irradiation, the composite effectively collects and converts the light energy into thermal energy, and the converted thermal energy is stored in the PCM and released in an elongated period of time for sustained utilization. This study provides a promising route for sustainable utilization of solar energy. PMID:27430282

  17. Marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS

    Directory of Open Access Journals (Sweden)

    Luciano Ribeiro CORREA NETTO

    2015-10-01

    Full Text Available Marginal integrity is one of the most crucial aspects involved in the clinical longevity of resin composite restorations.Objective To analyze the marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS.Material and Methods A base composite (B was produced with an organic matrix with UDMA/TEGDMA and 70 wt.% of barium borosilicate glass particles. To produce the model composite, 25 wt.% of UDMA were replaced by POSS (P25. The composites P90 and TPH3 (TP3 were used as positive and negative controls, respectively. Marginal integrity (%MI was analyzed in bonded class I cavities. The volumetric polymerization shrinkage (%VS and the polymerization shrinkage stress (Pss - MPa were also evaluated.Results The values for %MI were as follows: P90 (100% = TP3 (98.3% = B (96.9% > P25 (93.2%, (p<0.05. The %VS ranged from 1.4% (P90 to 4.9% (P25, while Pss ranged from 2.3 MPa (P90 to 3.9 MPa (B. For both properties, the composite P25 presented the worst results (4.9% and 3.6 MPa. Linear regression analysis showed a strong positive correlation between %VS and Pss (r=0.97, whereas the correlation between Pss and %MI was found to be moderate (r=0.76.Conclusions The addition of 25 wt.% of POSS in methacrylate organic matrix did not improve the marginal integrity of class I restorations. Filtek P90 showed lower polymerization shrinkage and shrinkage stress when compared to the experimental and commercial methacrylate composite.

  18. Silorane- and high filled-based"low-shrinkage" resin composites: shrinkage, flexural strength and modulus

    Directory of Open Access Journals (Sweden)

    Cesar Augusto Galvão Arrais

    2013-04-01

    Full Text Available This study compared the volumetric shrinkage (VS, flexural strength (FS and flexural modulus (FM properties of the low-shrinkage resin composite Aelite LS (Bisco to those of Filtek LS (3M ESPE and two regular dimethacrylate-based resin composites, the microfilled Heliomolar (Ivoclar Vivadent and the microhybrid Aelite Universal (Bisco. The composites (n = 5 were placed on the Teflon pedestal of a video-imaging device, and VS was recorded every minute for 5 min after 40 s of light exposure. For the FS and FM tests, resin discs (0.6 mm in thickness and 6.0 mm in diameter were obtained (n = 12 and submitted to a piston-ring biaxial test in a universal testing machine. VS, FS, and FM data were submitted to two-way repeated measures and one-way ANOVA, respectively, followed by Tukey's post-hoc test (a = 5%. Filtek LS showed lower VS than did Aelite LS, which in turn showed lower shrinkage than did the other composites. Aelite Universal and Filtek LS exhibited higher FS than did Heliomolar and Aelite LS, both of which exhibited the highest FM. No significant difference in FM was noted between Filtek LS and Aelite Universal, while Heliomolar exhibited the lowest values. Aelite LS was not as effective as Filtek LS regarding shrinkage, although both low-shrinkage composites showed lower VS than did the other composites. Only Filtek LS exhibited FS and FM comparable to those of the regular microhybrid dimethacrylate-based resin composite.

  19. A new shading concept based on natural tooth color applied to direct composite restorations

    OpenAIRE

    Dietschi, Didier; Ardu, Stefano; Krejci, Ivo

    2006-01-01

    Patient demands have prompted manufacturers to improve intrinsic optical properties of resin composites and clinicians to refine application procedures. The aim of this study is to present a shading concept based on colorimetric L*a*b* and contrast ratio data of human dentin and enamel.

  20. 18-year survival of posterior composite resin restorations with and without glass ionomer cement as base.

    NARCIS (Netherlands)

    Sande, F.H. van de; Rosa Rodolpho, P.A. Da; Basso, G.R.; Patias, R.; Rosa, Q.F. da; Demarco, F.F.; Opdam, N.J.M.; Cenci, M.S.

    2015-01-01

    OBJECTIVE: Advantages and disadvantages of using intermediate layers underneath resin-composite restorations have been presented under different perspectives. Yet, few long-term clinical studies evaluated the effect of glass-ionomer bases on restoration survival. The present study investigated the i

  1. A Flexible UV-Vis-NIR Photodetector based on a Perovskite/Conjugated-Polymer Composite.

    Science.gov (United States)

    Chen, Shan; Teng, Changjiu; Zhang, Miao; Li, Yingru; Xie, Dan; Shi, Gaoquan

    2016-07-01

    A lateral photodetector based on the bilayer composite film of a perovskite and a conjugated polymer is reported. It exhibits significantly enhanced responsivity in the UV-vis region and sensitive photoresponse in the near-IR (NIR) region at a low applied voltage. This broadband photodetector also shows excellent mechanical flexibility and improved environmental stability.

  2. A model-based approach to studying changes in compositional heterogeneity

    NARCIS (Netherlands)

    Baeten, L.; Warton, D.; Calster, van H.; Frenne, De P.; Verstraeten, G.; Bonte, D.; Bernhardt-Romermann, M.; Cornelis, R.; Decocq, G.; Eriksson, O.; Hommel, P.W.F.M.

    2014-01-01

    1. Non-random species loss and gain in local communities change the compositional heterogeneity between communities over time, which is traditionally quantified with dissimilarity-based approaches. Yet, dissimilarities summarize the multivariate species data into a univariate index and obscure the s

  3. Casein and soybean protein-based thermoplastics and composites as alternative biodegradable polymers for biomedical applications

    NARCIS (Netherlands)

    Vaz, C.M.; Fossen, M.; Tuil, van R.F.; Graaf, de L.A.; Reis, R.L.; Cunha, A.M.

    2003-01-01

    This work reports on the development and characterization of novel meltable polymers and composites based on casein and soybean proteins. The effects of inert (Al2O3) and bioactive (tricalcium phosphate) ceramic reinforcements over the mechanical performance, water absorption, and bioactivity behavi

  4. High tensile strength fly ash based geopolymer composite using copper coated micro steel fiber

    DEFF Research Database (Denmark)

    Ranjbar, Navid; Mehrali, Mehdi; Mehrali, Mohammad;

    2016-01-01

    -matrix interaction. In this present study, effects of micro steel fibers (MSF) incorporation on mechanical properties of fly ash based geopolymer was investigated at different volume ratio of matrix. Various properties of the composite were compared in terms of fresh state by flow measurement and hardened state...

  5. Vibration based Structural Health Monitoring of a composite T-beam

    NARCIS (Netherlands)

    Ooijevaar, T.H.; Loendersloot, R.; Warnet, L.L.; Boer, de A.; Akkerman, R.

    2010-01-01

    A vibration based damage identification method is investigated experimentally for a 2.5-dimensional composite structure. The dynamic response of an intact and a locally delaminated 16-layer unidirectional carbon fibre PEKK reinforced T-beam is considered. A force–vibration set-up, including a laser

  6. A Multiple-Neighborhood-Based Parallel Composite Local Search Algorithm for Timetable Problem

    Institute of Scientific and Technical Information of China (English)

    颜鹤; 郁松年

    2004-01-01

    This paper presents a parallel composite local search algorithm based on multiple search neighborhoods to solve a special kind of timetable problem. The new algorithm can also effectively solve those problems that can be solved by general local search algorithms. Experimental results show that the new algorithm can generate better solutions than general local search algorithms.

  7. Graphene-Based Hybrid Composites for Efficient Thermal Management of Electronic Devices.

    Science.gov (United States)

    Shtein, Michael; Nadiv, Roey; Buzaglo, Matat; Regev, Oren

    2015-10-28

    Thermal management has become a critical aspect in next-generation miniaturized electronic devices. Efficient heat dissipation reduces their operating temperatures and insures optimal performance, service life, and efficacy. Shielding against shocks, vibrations, and moisture is also imperative when the electronic circuits are located outdoors. Potting (or encapsulating) them in polymer-based composites with enhanced thermal conductivity (TC) may provide a solution for both thermal management and shielding challenges. In the current study, graphene is employed as a filler to fabricate composites with isotropic ultrahigh TC (>12 W m(-1) K(-1)) and good mechanical properties (>30 MPa flexural and compressive strength). To avoid short-circuiting the electronic assemblies, a dispersion of secondary ceramic-based filler reduces the electrical conductivity and synergistically enhances the TC of composites. When utilized as potting materials, these novel hybrid composites effectively dissipate the heat from electronic devices; their operating temperatures decrease from 110 to 37 °C, and their effective thermal resistances are drastically reduced, by up to 90%. The simple filler dispersion method and the precise manipulation of the composite transport properties via hybrid filling offer a universal approach to the large-scale production of novel materials for thermal management and other applications. PMID:26445279

  8. Circular Functions Based Comprehensive Analysis of Plastic Creep Deformations in the Fiber Reinforced Composites

    Science.gov (United States)

    Monfared, Vahid

    2016-06-01

    Analytically based model is presented for behavioral analysis of the plastic deformations in the reinforced materials using the circular (trigonometric) functions. The analytical method is proposed to predict creep behavior of the fibrous composites based on basic and constitutive equations under a tensile axial stress. New insight of the work is to predict some important behaviors of the creeping matrix. In the present model, the prediction of the behaviors is simpler than the available methods. Principal creep strain rate behaviors are very noteworthy for designing the fibrous composites in the creeping composites. Analysis of the mentioned parameter behavior in the reinforced materials is necessary to analyze failure, fracture, and fatigue studies in the creep of the short fiber composites. Shuttles, spaceships, turbine blades and discs, and nozzle guide vanes are commonly subjected to the creep effects. Also, predicting the creep behavior is significant to design the optoelectronic and photonic advanced composites with optical fibers. As a result, the uniform behavior with constant gradient is seen in the principal creep strain rate behavior, and also creep rupture may happen at the fiber end. Finally, good agreements are found through comparing the obtained analytical and FEM results.

  9. Characterization of composite materials based on cement-ceramic powder blended binder

    Science.gov (United States)

    Kulovaná, Tereza; Pavlík, Zbyšek

    2016-06-01

    Characterization of newly developed composite mortars with incorporated ceramic powder coming from precise brick cutting as partial Portland cement replacement up to 40 mass% is presented in the paper. Fine ceramic powder belongs to the pozzolanic materials. Utilization of pozzolanic materials is accompanied by lower request on energy needed for Portland clinker production which generally results in lower production costs of blended binder and lower CO2 emission. In this paper, the ceramic powder is used in cement based mortar composition in amount of 8, 16, 24, 32, and 40 mass% of cement. Chemical composition of ceramic powder is analyzed by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramics is accessed on laser diffraction principle. For 28 days cured mortar samples, basic physical and mechanical properties are experimentally determined. The obtained results demonstrate that ceramic powder has potential to replace a part of Portland cement in composition of cement based composites and to reduce negative environmental impact of their production.

  10. Bioinspired Multifunctional Paper-Based rGO Composites for Solar-Driven Clean Water Generation.

    Science.gov (United States)

    Lou, Jinwei; Liu, Yang; Wang, Zhongyong; Zhao, Dengwu; Song, Chengyi; Wu, Jianbo; Dasgupta, Neil; Zhang, Wang; Zhang, Di; Tao, Peng; Shang, Wen; Deng, Tao

    2016-06-15

    Reusing polluted water through various decontamination techniques has appeared as one of the most practical approaches to address the global shortage of clean water. Rather than relying on single decontamination mechanism, herein we report the preparation and utilization of paper-based composites for multifunctional solar-driven clean water generation that is inspired by the multiple water purification approaches in biological systems. The reduced graphene oxide (rGO) sheets within such composites can efficiently remove organic contaminants through physical adsorption mechanism. Under solar irradiation, the floating rGO composites can instantly generate localized heating, which not only can directly generate clean water through distillation mechanism but also significantly enhance adsorption removal performance with the assistance of upward vapor flow. Such porous-structured paper-based composites allow for facile incorporation of photocatalysts to regenerate clean water out of contaminated water with combined adsorption, photodegradation, and interfacial heat-assisted distillation mechanisms. Within a homemade all-in-one water treatment device, the practical applicability of the composites for multifunctional clean water generation has been demonstrated.

  11. Bio-based composites from stone groundwood applied to new product development

    Directory of Open Access Journals (Sweden)

    Pere Mutje

    2012-11-01

    Full Text Available This paper deals with the product design, engineering, and material selection intended for the manufacturing of an eco-friendly chair. The final product is expected to combine design attributes with technical and legal feasibility with the implementation of new bio-based materials. Considering the industrial design, a range of objectives and trends were determined after setting the market requirements, and the final concept was proposed and modeled. The product geometry, production technology, and legal specifications were the input data for product engineering. The material selection was based on the technical requirements. Polypropylene (PP composite materials based on coupled-fiberglass, sized-fiberglass, and coupled-stone ground wood reinforcements were prepared and characterized. Final formulations based on these PP composites are proposed and justified.

  12. Spent fuel isotopic composition data base system on WWW. SFCOMPO on W3

    International Nuclear Information System (INIS)

    Spent Fuel Composition Data Base System 'SFCOMPO' has been developed on IBM compatible PC. This data base system is not widely used, since users must purchase the data base software by themselves. 'SFCOMPO on W3' is a system to overcome this problem. User can search and visualize the data in the data base by accessing WWW server through the Internet from local machine. Only a browsing software to access WWW should be prepared. It enables us to easily search data of spent fuel composition if we can access the Internet. This system can be operated on WWW server machine which supports use of Common Gateway Interface (CGI). This report describes the background of the development of SFCOMPO on W3 and is it's user's manual. (author)

  13. Properties and interfacial microstructure of cement-based materials with composite micro-grains

    Institute of Scientific and Technical Information of China (English)

    FENG Qi; BA Heng-jing; LIU Jun-zhe

    2005-01-01

    Silica fume, fly ash and nano-fiber mineral materials (NR powder) are employed to incorporate into cement-based materials. According to the grain grading mathematical model of cement-based materials, two packing systems, namely, spherical grading system and nano-fiber reinforced system were designed. Properties and interfacial microstructure of the two systems were studied according to secondary interface theory. It was shown that nano-fiber mineral materials can improve the grain grading of the admixture, increase the density of the system, improve the microstructure of the interface and the hardened paste, and enhance the uniformity of cement-based materials mixed with composite micro-grains and greatly increase their wearable rigidity and flexure strength. In this paper, two kinds of interface models, including spherical grain model and nano-fiber reinforced interface model of the cement-based materials mixed with composite micro-grains, were brought forward.

  14. Spent fuel isotopic composition data base system on WWW. SFCOMPO on W3

    Energy Technology Data Exchange (ETDEWEB)

    Suyama, Kenya [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-11-01

    Spent Fuel Composition Data Base System `SFCOMPO` has been developed on IBM compatible PC. This data base system is not widely used, since users must purchase the data base software by themselves. `SFCOMPO on W3` is a system to overcome this problem. User can search and visualize the data in the data base by accessing WWW server through the Internet from local machine. Only a browsing software to access WWW should be prepared. It enables us to easily search data of spent fuel composition if we can access the Internet. This system can be operated on WWW server machine which supports use of Common Gateway Interface (CGI). This report describes the background of the development of SFCOMPO on W3 and is it`s user`s manual. (author)

  15. Development of (fe–b–c-based filler for wear-resistant composite coatings

    Directory of Open Access Journals (Sweden)

    О. V. Sukhovа

    2014-12-01

    Full Text Available Purpose. Development of multi-alloyed filler for abrasive wear-resistant composites. Methodology. The methods of microstructural, X-ray and energy-dispersive X-ray analyses were used to achieve research purpose. Micro-mechanical properties of structural constituents and abrasive wear-resistance of composites were determined. Findings. The complete dissolution of chromium and vanadium in the borides of Fe2В and FeВ that are initial structural constituents of Fe–В–С peritectic alloys has been established. These elements primarily dissolve in iron monoboride. Dissolution of molybdenum and niobium is not practically observed. As a result the phases of Мо2В, Мо2(В,С or NbВ2 can be seen in the structure. Alloying with chromium and vanadium increases compression strength and crack resistance coefficient, but that with molybdenum and niobium enhances total microhardness and hardness of the alloys. Structure formation of the interfaces between the filler and the binder of the composites based on МNМts 20-20 binder is governed by dissolution and diffusion processes when multi-alloyed (Fe–В–С alloy is applied as filler of the composites. The phase and the structural composition of contact interaction zones can be explained by re-crystallization of the filler surface layers after dissolution caused by contact with the molten binder. Consequently the macroheterogeneous structure of the composites is free of defects and strong adhesion between the filler and the binder is assured. Contact interaction intensity can be controlled by the choice of temperature- and-time infiltration regimes. Originality. The peculiarities in the formation of structure and properties of Fe2В- and FeВ-based solid solutions observed in the structure of the Fe–В–С peritectic alloys were investigated that allowed us to recommend composition of multicomponent alloy to be applied as filler of (Cu–Ni–Mn-matrix macroheterogeneous composites. Practical

  16. Rheological behavior of composites based on carbon fibers recycled from aircraft waste

    OpenAIRE

    Marcaníková, Lucie; Hausnerová, Berenika; Kitano, Takeshi

    2009-01-01

    Rheological investigation of composite materials prepared from the recycled aircraft waste materials based on thermoset (epoxy/resin) matrix and long carbon fibers (CF) is presented with the aim of their utilization in consumer industry applications. The carbon fibers recovered via thermal process of pyrolysis were cut into about 150 pm length and melt mixed with thermoplastic matrices based on polypropylene (PP) and polyamide 6 (PA) and various modifiers - ethylene-ethyl acrylate-maleic anhy...

  17. Processing, mechanical and thermophysical properties of silicon nitride based composites with carbon nanotubes and graphene

    Directory of Open Access Journals (Sweden)

    O. Koszor

    2007-12-01

    Full Text Available Silicon nitride based composites with different amount (1, 2 and 3 wt% of multi-wall and single-wall carbon nanotubes, and graphene have been prepared. Optimisation of the manufacturing processes has been conducted to preserve the carbon nanotubes in composites and to avoid damaging during high temperature processing. The first results show that carbon nanotubes have a good contact to the surface of silicon nitride grains. In the case of increase of sintering pressure an increase of bending strength was achieved. It was found that microstructure features achieved by properly designed sintering parameters are the main responsible factors for the strength improvements.

  18. Production of Heat Resistant Composite based on Siloxane Elastomer and Multiwall Carbon Nanotubes

    Science.gov (United States)

    Bessonov, I. V.; Karelina, N. V.; Kopitsyna, M. N.; Morozov, A. S.; Reznik, S. V.; Skidchenko, V. Yu.

    2016-02-01

    Development of a new generation of composite with unique thermal properties is an important task in the fields of science and technology where material is operated at high temperatures and exposure to a short-wave radiation. Recent studies show that carbon nanomaterials (fullerenes and carbon nanotubes) could improve the thermal, radiation and thermal-oxidative stability of the polymer matrix. In this article the development of a new heat resistant composite based on elastomer and carbon nanotubes (CNT) was performed and physicochemical properties of final product were evaluated.

  19. Some Aspects Of Infiltration Of High Speed Steel Based Composites With Iron Addition

    Directory of Open Access Journals (Sweden)

    Madej M.

    2015-06-01

    Full Text Available Attempts have been made to describe the influence of the production process parameters and additions of iron powders on properties of copper infiltrated HSS based composites. The powder compositions used to produce skeletons for further infiltration were: M3/2, M3/2+20% Fe and M3/2+50% Fe. The powders were cold pressed at 800 MPa. The infiltration process was carried out in vacuum. Both green compacts and preforms sintered for 60 minutes at 1150°C in vacuum were contact infiltrated with copper to yield final densities exceeding 97% of the theoretical value.

  20. Ply-based Optimization of Laminated Composite Shell Structures under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Sørensen, Rene; Lund, Erik

    2012-01-01

    This work concerns a new ply-based parameterization for performing simultaneous material selection and topology optimization of fiber reinforced laminated composite structures while ensuring that a series of different manufacturing constraints are fulfilled. The material selection can either...... be performed on the basis of different materials, and/or consist of discrete selection of the same orthotropic material with different orientations of the fibers. The problem considered is the optimization of a general laminated composite shell structure with respect to maximum stiffness (minimum compliance...

  1. Influence of surface treatments to repair recent fillings of silorane-and methacrylate-based composites

    OpenAIRE

    Marina Kaneko; Ricardo Armini Caldas; Victor Pinheiro Feitosa; Rafael Leonardo Xediek Consani; Schneider, Luis Felipe J.; Ataís Bacchi

    2015-01-01

    Purpose: The aim of this study was to evaluate the tensile bond strength (TBS) of repairs in recent fillings of methacrylate- (MBC) or silorane-based composites (SBC) subsequent to different surface treatments. Materials and Methods: Fifty slabs of Filtek P60 (3M ESPE, St Paul, USA) and Filtek P90 (3M ESPE) were stored for 10 days in distilled water at 37°C. The surface of adhesion was abraded with a 600-grit silicone paper and repaired using each respective composite: G1, no treatment (...

  2. Dynamic measurement of local displacements within curing resin-based dental composite using optical coherence elastography

    Science.gov (United States)

    Tomlins, Peter H.; Rahman, Mohammed Wahidur; Donnan, Robert S.

    2016-04-01

    This study aimed to determine the feasibility of using optical coherence elastography to measure internal displacements during the curing phase of a light-activated, resin-based composite material. Displacement vectors were spatially mapped over time within a commercial dental composite. Measurements revealed that the orientation of cure-induced displacement vectors varied spatially in a complex manner; however, each vector showed a systematic evolution with time. Precision of individual displacements was estimated to be ˜1 to 2 μm, enabling submicrometer time-varying displacements to be detected.

  3. Electronic modification of Cu-based chalcopyrite semiconductors induced by lattice deformation and composition alchemy

    Science.gov (United States)

    Jiang, F. D.; Feng, J. Y.

    2008-02-01

    Using first principles calculation, we systematically investigate the electronic modification of Cu-based chalcopyrite semiconductors induced by lattice deformation and composition alchemy. It is shown that the optical band gap Eg is remarkably sensitive to the anion displacement μ, resulting from the opposite shifts of conduction band minimum and valence band maximum. Meanwhile, the dependence of structural parameters of alloyed compounds on alloy composition x is demonstrated for both cation and anion alloying. The d orbitals of group-III cations are found to be of great importance in the calculation. Abnormal changes in the optical band gap Eg induced by anion alloying are addressed.

  4. Electronic modification of Cu-based chalcopyrite semiconductors induced by lattice deformation and composition alchemy

    International Nuclear Information System (INIS)

    Using first principles calculation, we systematically investigate the electronic modification of Cu-based chalcopyrite semiconductors induced by lattice deformation and composition alchemy. It is shown that the optical band gap Eg is remarkably sensitive to the anion displacement μ, resulting from the opposite shifts of conduction band minimum and valence band maximum. Meanwhile, the dependence of structural parameters of alloyed compounds on alloy composition x is demonstrated for both cation and anion alloying. The d orbitals of group-III cations are found to be of great importance in the calculation. Abnormal changes in the optical band gap Eg induced by anion alloying are addressed

  5. Morphology and transport in biodegradable polymer compositions based on poly(3-hydroxybutyrate) and polyamide 54C

    Energy Technology Data Exchange (ETDEWEB)

    Zhul' kina, A. L.; Ivantsova, E. L.; Filatova, A. G.; Kosenko, R. Yu.; Gumargalieva, K. Z.; Iordanskii, A. L., E-mail: iordan@chph.ras.ru [Russian Academy of Sciences, Semenov Institute of Chemical Physics (Russian Federation)

    2009-05-15

    Complex investigation of the equilibrium sorption of water, diffusive transport of antiseptic, and morphology of mixed compositions based on polyoxybutirate and polyamide resin 54C has been performed to develop and analyze new biodegradable polymer compositions for controlled release of medicinal substances. Samples of mixtures were prepared by two methods: pressing under pressure and solvent evaporation from a polymer solution. The samples were compared and their morphology was analyzed by scanning electron microscopy. It is shown that the component ratio in the obtained mixtures affects their morphological, transport, and sorption characteristics.

  6. Effect of the fiber orientation on the deformation mechanisms of magnesium-alloy based composite

    Energy Technology Data Exchange (ETDEWEB)

    Farkas, Gergely [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Prague (Czech Republic); Trojanová, Zuzanka, E-mail: ztrojan@met.mff.cuni.cz [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Prague (Czech Republic); Száraz, Zoltán [Institute for Energy and Transport, Joint Research Centre, Westerduinweg 3, NL-1755ZG Petten (Netherlands); Minárik, Peter; Máthis, Kristián [Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 121 16 Prague (Czech Republic)

    2015-09-03

    The influence of the orientation of the fiber reinforcement on the deformation mechanisms of Mg–Al–Ca alloy-based composite has been investigated in-situ using acoustic emission and neutron diffraction methods. Results indicate that the twinned volume is the smallest, when the fibers plane is perpendicular to the loading direction. Residual thermal stresses having a tensile character are present in the as-received composites, which gradually vanishing during compressive straining. The load transfer from the matrix to fiber has been found more effective for specimens with fiber planes aligned with the loading direction, which is in agreement with the theoretical shear-lag model.

  7. Optimization of Ni-Based WC/Co/Cr Composite Coatings Produced by Multilayer Laser Cladding

    OpenAIRE

    Andrea Angelastro; Sabina L. Campanelli; Giuseppe Casalino; Antonio D. Ludovico

    2013-01-01

    As a surface coating technique, laser cladding (LC) has been developed for improving wear, corrosion, and fatigue properties of mechanical components. The main advantage of this process is the capability of introducing hard particles such as SiC, TiC, and WC as reinforcements in the metallic matrix such as Ni-based alloy, Co-based alloy, and Fe-based alloy to form ceramic-metal composite coatings, which have very high hardness and good wear resistance. In this paper, Ni-based alloy (Colmonoy ...

  8. Self-monitoring electrically conductive asphalt-based composite containing carbon fillers

    Institute of Scientific and Technical Information of China (English)

    WU Shao-peng; LIU Xiao-ming; YE Qun-shan; LI Ning

    2006-01-01

    A new novel function materials,structure self-monitoring asphalt-based composite was introduced. The results show that the output resistance of electrically conductive asphalt-based composites would change under cyclic loading and vehicle loading action. The resistance change of conductive asphalt-based composites was aroused by the variation of its interior structure. When the fatigue failure was studied,the larger cracks cut the continuous electrically conductive path and the electron is difficult to overcome the potential barrier of gap. In the early period,the slight deformation and microcrack may be recovered due to the viscoelasticity character of asphalt,which leads to some cracks close again,the output resistance changes a little. But with the shear process performs continuously,the cracks become larger and larger,which would cut the conductive path and block off the transition of electrons,and if the cracks are large enough,the pitch-matrix composites containing carbon fillers will lose electrically conductive function. When the rutting failure was studied,the flowage of conductive substance results in the decrease of substance due to electrically conducting and conductive path decreasing. The decrease of electron volume contribute to electrically conducting and large stone aggregate prevent the electron from transiting. In a word,the variation of output resistance is aroused by the variation of interior structure completely.

  9. PVC-based composite material containing recycled non-metallic printed circuit board (PCB) powders.

    Science.gov (United States)

    Wang, Xinjie; Guo, Yuwen; Liu, Jingyang; Qiao, Qi; Liang, Jijun

    2010-12-01

    The study is directed to the use of non-metallic powders obtained from comminuted recycled paper-based printed circuit boards (PCBs) as an additive to polyvinyl chloride (PVC) substrate. The physical properties of the non-metallic PCB (NMPCB) powders were measured, and the morphological, mechanical and thermal properties of the NMPCB/PVC composite material were investigated. The results show that recycled NMPCB powders, when added below a threshold, tended to increase the tensile strength and bending strength of PVC. When 20 wt% NMPCB powders (relative to the substrate PVC) of an average diameter of 0.08 mm were added, the composite tensile strength and bending strength reached 22.6 MPa and 39.83 MPa, respectively, representing 107.2% and 123.1% improvement over pure PVC. The elongation at break of the composite material reached 151.94% of that of pure PVC, while the Vicat softening temperature of the composite material did not increase significantly compared to the pure PVC. The above results suggest that paper-based NMPCB powders, when used at appropriate amounts, can be effective for toughening PVC. Thus, this study suggests a new route for reusing paper-based NMPCB, which may have a significant beneficial environmental impact.

  10. Researches on the behaviour of cellular antiballistic composites based on AlMg-SiC alloys

    Science.gov (United States)

    Bălţătescu, O.; Florea, R. M.; Rusu, I.; Carcea, I.

    2015-11-01

    The researches presented in this paper refers basically to the impact of a small/medium caliber bullet shot on a light armor built on the base of a AlMg-SiC metallic composite cellular/foam. Thus, we study the antiballistic behavior and protection properties of the armor, based on the effects that occur at the impact zone of the bullet with the composite surface. We performed an antiballistic behavior modeling by means of a finite element analysis, based on a "multi grid" Fast Finite Element (FFE) system. We used for this purpose the DYNA 2D software package. The obtained samples show after the impact the occurrence of concentration / deformation pores effect and intercellular cracks development to the interior of the composite. Those effects, depending on speed, mass and length of the projectile ballistic trajectory, reduce zonal tensions due to the effect of cell walls deformation. It was obtained a good correlation between modeling results and the electron microscope analyse of the impact area. It is worth mentioning that almost all values for impact energy absorbed by the composite armor are in the protection active zone provided by it.

  11. Highly Thermally Conductive Composite Papers Prepared Based on the Thought of Bioinspired Engineering.

    Science.gov (United States)

    Yao, Yimin; Zeng, Xiaoliang; Sun, Rong; Xu, Jian-Bin; Wong, Ching-Ping

    2016-06-22

    The rapid development of modern electronics and three-dimensional integration sets stringent requirements for efficient heat removal of thermal-management materials to ensure the long lifetime of the electronics. However, conventional polymer composites that have been used widely as thermal-management materials suffer from undesired thermal conductivity lower than 10 W m(-1) K(-1). In this work, we report a novel thermally conductive composite paper based on the thought of bioinspired engineering. The advantage of the bioinspired papers over conventional composites lies in that they possess a very high in-plane thermal conductivity up to 21.7 W m(-1) K(-1) along with good mechanical properties and high electrical insulation. We attribute the high thermal conductivity to the improved interfacial interaction between assembled components through the introduction of silver nanoparticles and the oriented structure based on boron nitride nanosheets and silicon carbide nanowires. This thought based on bioinspired engineering provides a creative opportunity for design and fabrication of novel thermally conductive materials, and this kind of composite paper has potential applications in powerful integrated microelectronics. PMID:27253387

  12. Leaching of the potentially toxic pollutants from composites based on waste raw material

    Directory of Open Access Journals (Sweden)

    Terzić Anja

    2012-01-01

    Full Text Available The disposal of the fly ash generated in coal based power-plants may pose a significant risk to the environment due to the possible leaching of hazardous pollutants, such as toxic metals. Also, there is a risk of leaching even when fly ash is built-in the construction composites. Fly ashes from various landfills were applied in several composite samples (mortar, concrete and brick without any physical or thermal pre-treatment. The leachability of the potentially toxic pollutants from the fly ash based products was investigated. The leaching behavior and potential environmental impact of the 11 potentially hazardous elements was tracked: Pb, Cd, Zn, Cu, Ni, Cr, Hg, As, Ba, Sb and Se. A detailed study of physico-chemical characteristics of the fly ash, with accent on trace elements and the chemical composition investigation is included. Physico/chemical properties of fly ash were investigated by means of X-ray fluorescence, differential thermal analysis and X-ray diffraction methods. Scanning electron microscope was used in microstructural analysis. The results show that most of the elements are more easily leachable from the fly ash in comparison with the fly ash based composites. The leaching of investigated pollutants is within allowed range thus investigated fly ashes can be reused in construction materials production.

  13. Effect of In-Office Carbamide Peroxide-Based Tooth Bleaching System on Wear Resistance of Silorane-Based and Methacrylate-Based Dental Composites

    Science.gov (United States)

    Hasani Tabatabaei, Masoumeh; Sheikhzadeh, Sedigheh; Ghasemi Monfared Rad, Hamidreza; Beygi, Ahmad

    2015-01-01

    Objectives: Several studies have assessed the characteristics and properties of silorane-based composites and adhesive systems. Considering the extensive application of tooth-whitening agents, possible deteriorative effects of tooth bleaching agents on these restorative materials must be studied. The aim of this study was to evaluate the effect of an in-office carbamide peroxide-based tooth bleaching agent on the wear resistance of a silorane-based and a conventional microhybrid dimethyl methacrylate-based dental composite with two different application times. Materials and Methods: Thirty cylindrical specimens were made of Z250 and P90 dental composite resins (n=15 for each composite). Samples made of each composite were divided into three groups (n=5) for immersion in an in-office bleaching agent (Opalescence® Quick 45%) for either three or eight hours or saline solution (control). Wear tests were conducted after bleaching using a pin-on disk apparatus under the load of 40N at a constant sliding speed of 0.5 ms−1 for a sliding distance of 300 m. The samples were weighed before and after the wear test. Repeated measures ANOVA was used to statistically analyze the obtained data (α=0.05). Results: There was a significant decrease in the weight of samples after the wear test (P0.05). Conclusion: Bleaching for three or eight hours using 45% carbamide peroxide had no deteriorative effect on the wear resistance of Z250 and P90 composites. PMID:27123014

  14. Economical bridge solutions based on innovative composite dowels and integrated abutments ecobridge

    CERN Document Server

    Băncilă, Radu

    2015-01-01

    This book is an outcome of the research project “ECOBRIDGE – Demonstration of ECOnomical BRIDGE solutions based on innovative composite dowels and integrated abutments – RFCS – CT 2010-00024”, which has been co-funded by the Research Fund for Coal and Steel (R.F.C.S.) of the European Community. The main topics of the book are the following: design of integral bridges, innovative composite dowels for the shear transmission, construction of bridges, structural analysis of bridges and monitoring. The book joins the technical experience and the contributions of the involved research partners. The technical content of all the papers is present-day in the field of the design, construction and monitoring of innovative composite bridges. The efficient design and construction improve and consolidate the market position of steel construction and steel producing industry. In addition, the advanced forms of construction are contributing to savings in material and energy consumption for the structure during prod...

  15. Mathematical Model For Autoclave Curing Of Unsaturated Polyester Based Composite Materials

    Directory of Open Access Journals (Sweden)

    Adnan A. Abdul Razak

    2013-05-01

    Full Text Available Heat transfer process involved in the autoclave curing of fiber-reinforced thermosetting composites is investigated numerically. A model for the prediction of the temperature and the extent of the reaction across the laminate thickness during curing process in the autoclave of unsaturated polyester based composite has been developed. The governing equation for one dimensional heat transfer, and accounting for the heat generation due to the exothermic cure reaction in the composites had been used.  It was found that the temperature at the central of the laminate increases up to the external imposed temperature, because of the thermal conductivity of the resin and fiber. The heat generated by the exothermic reaction of the resin is not adequately removed; the increase in the temperature at the center increases the resins rate reaction, which in turn generates more heat.

  16. Composite membranes based on a novel benzimidazole grafted PEEK and SPEEK for fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongtao; Zhang, Gang; Ma, Wenjia; Zhao, Chengji; Zhang, Yang; Han, Miaomiao; Zhu, Jing; Liu, Zhongguo; Wu, Jing; Na, Hui [Alan G MacDiarmid Institute, College of Chemistry, Jilin University, Changchun 130012 (China)

    2010-10-15

    Poly(ether ether ketone) (PEEK) and sulfonated poly(ether ether ketone) (SPEEK, IEC = 2.07 mequiv.g{sup -1}) have been synthesized via nucleophilic aromatic substitution reaction. Bromomethylated poly(ether ether ketone) (PEEK-Br) is then prepared and reacted with 2-benzimidazolethiol to obtain the benzimidazole grafted poly(ether ether ketone) (PEEK-BI). The structures of PEEK-Br and PEEK-BI are characterized by {sup 1}H NMR spectra. Composite membranes based on SPEEK and PEEK-BI are prepared and their properties used for fuel cells are studied in detail. The results show that the composite membranes exhibit greatly improved mechanical properties as well as reduced water uptake and methanol permeability compared with the pristine SPEEK membrane. The increased oxidative stability and selectivity indicate that the composite membranes are promising to be used as proton exchange membranes. (author)

  17. Warm compaction of Al2O3 particulate reinforced powder metallurgy iron-base composite

    Institute of Scientific and Technical Information of China (English)

    倪东惠; 陈维平; 肖志瑜; 邵明; 张双益

    2002-01-01

    Mechanical properties of the warm compacted alumina particulate reinforced powder metallurgy composite materials was compared with those of the materials obtained by conventional cold compaction. Factors affecting the properties of the warm compacted material such as compaction temperature, lubricant content and alumina content were studied. A 3%(mass fraction) alumina particulate reinforced iron-base composite with a green density of 7.0g/cm3 can be obtained by pressing the powder with a pressure of 700MPa at 175℃. The sintered materials have a density of 6.88g/cm3, a tensile strength of 512MPa and an elongation of 1.3%. Results show that as alumina content increases, density and mechanical properties of the composite decrease.

  18. Densely Packed Linear Assembles of Carbon Nano tube Bundles in Polysiloxane-Based Nano composite Films

    International Nuclear Information System (INIS)

    Linear assemblies of carbon nano tubes (LACNTs) were fabricated and controlled in polysiloxane-based nano composite films and the effects of the LACNTs on the thermal and electrical properties of the films were investigated. CNTs were dispersed by mechanical stirring and sonication in a prepolymer of polysiloxane. Homogeneous suspensions were cast on polyamide spacers and oriented by linear-assembly by applying DC and switching DC electric fields before the mixture became cross-linked. Densely packed LACNTs that fixed the composite film surfaces were fabricated with various structures and thicknesses that depended on the DC and switching DC conditions. Polymer nano composites with different LACNT densities exhibited enhanced thermal and electrical conductivities and high optical transmittances. They are considered promising structural materials for electronic sectors in automotive and aerospace applications

  19. Fabrication and microstructure of Fe-based amorphous composite coatings by laser cladding

    Institute of Scientific and Technical Information of China (English)

    Zhu Qingjun; Zou Zengda; Qu Shiyao; Wang Xinhong

    2008-01-01

    Fe-based amorphous composite coatings were fabricated on AISI 1045 steel by laser cladding. The results of the X-ray diffraction and transmission electron microscopy analyses show the coating is composed of an amorphous phase in majority and a nanocrystalline phase in minority. Phase composition of the coating changes along the depth of the coating. The reasonable scanning speed for fabricating an amorphous composite coating is 3 500mm/min when the laser power is 4 800W and the laser beam diameter is 2mm. If the scanning speed is lower than 3 500mm/min, the intensity of the two main diffraction peaks in X-ray diffraction patterns of the coatings decreases with the scanning speeds increasing. At the same time, a broad halo peak emerges and enlarges. High laser power and fast scanning speed are the essential conditions of amorphization. The coating exhibits high microhardness.

  20. High Temperature Joining and Characterization of Joint Properties in Silicon Carbide-Based Composite Materials

    Science.gov (United States)

    Halbig, Michael C.; Singh, Mrityunjay

    2015-01-01

    Advanced silicon carbide-based ceramics and composites are being developed for a wide variety of high temperature extreme environment applications. Robust high temperature joining and integration technologies are enabling for the fabrication and manufacturing of large and complex shaped components. The development of a new joining approach called SET (Single-step Elevated Temperature) joining will be described along with the overview of previously developed joining approaches including high temperature brazing, ARCJoinT (Affordable, Robust Ceramic Joining Technology), diffusion bonding, and REABOND (Refractory Eutectic Assisted Bonding). Unlike other approaches, SET joining does not have any lower temperature phases and will therefore have a use temperature above 1315C. Optimization of the composition for full conversion to silicon carbide will be discussed. The goal is to find a composition with no remaining carbon or free silicon. Green tape interlayers were developed for joining. Microstructural analysis and preliminary mechanical tests of the joints will be presented.

  1. Method of Obtaining a Composite Material Based on Small-Dispersed Particles

    Directory of Open Access Journals (Sweden)

    D.G. Batryshev

    2016-10-01

    Full Text Available In this work a method of obtaining a composite material based on small-dispersed particles is considered. Proposed method consists of two steps of separation, mechanical – rough separation and plasma – soft separation, and also of step of deposition a catalytic nanolayer by wet impregnation of separated particles in an aqueous solution of nickel nitrate. During such procedure a composite powder of small-dispersed zeolite particles with average diameter of 5 m and catalytic nickel layer was obtained. All obtained samples were studied on a Quanta 3D 200i scanning electron microscope. Microscopic analysis and obtained experimental results show, that increasing of dispersion of separated powder allows for increasing a mass of catalyst in the composite, and the used separation method in plasma for obtaining of particles with high dispersion do not erode a catalytic layer.

  2. Deep ultraviolet distributed Bragg reflectors based on graded composition AlGaN alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brummer, Gordie, E-mail: gbrummer@bu.edu [Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 (United States); Photonics Center, Boston University, Boston, Massachusetts 02215 (United States); Nothern, Denis [Photonics Center, Boston University, Boston, Massachusetts 02215 (United States); Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215 (United States); Nikiforov, A. Yu. [Photonics Center, Boston University, Boston, Massachusetts 02215 (United States); Moustakas, T. D., E-mail: tdm@bu.edu [Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 (United States); Photonics Center, Boston University, Boston, Massachusetts 02215 (United States); Division of Materials Science and Engineering, Boston University, Boston, Massachusetts 02215 (United States)

    2015-06-01

    Distributed Bragg reflectors (DBRs) with peak reflectivity at approximately 280 nm, based on compositionally graded Al{sub x}Ga{sub 1−x}N alloys, were grown on 6H-SiC substrates by plasma-assisted molecular beam epitaxy. DBRs with square, sinusoidal, triangular, and sawtooth composition profiles were designed with the transfer matrix method. The crystal structure of these DBRs was studied with high-resolution x-ray diffraction of the (1{sup ¯}015) reciprocal lattice point. The periodicity of the DBR profiles was confirmed with cross-sectional Z-contrast scanning transmission electron microscopy. The peak reflectance of these DBRs with 15.5 periods varies from 77% to 56% with corresponding full width at half maximum of 17–14 nm. Coupled mode analysis was used to explain the dependence of the reflectivity characteristics on the profile of the graded composition.

  3. Energetic Abilities of Solid Composite Propellants Based on 3,4,5-Trinitropyrazole and Ammonium Dinitramide

    Institute of Scientific and Technical Information of China (English)

    LEMPERT David B; CHUKANOV Nikita; SHU Yuan-jie

    2016-01-01

    The investigation aims at the expansion of the basis of formulations of solid composite propellants by introducing new compositions with lower sensitivity to mechanic impact and improved thermal stability .The formulations based on trinitropyrazole (TNP) contains a binder (a hydrocarbon or active one) ,aluminum and inorganic oxidizer ADN .The results show that a binary for‐mulation TNP + active binder (18% -19% )(volume fraction) with no metal is well designed which would achieve high specific im‐pulse (at Pc∶ Pa=40∶1) of 248 s ,high density of 1 .80 g/cm3 and combustion temperature Tc about 3450 K .In terms of energy , metal‐free compositions with TNP lose a bit to those with HMX ,only if HMX fraction in formulation is higher than 45% -50% .

  4. Thickness effect on electric resistivity on polystyrene and carbon black- based composites

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Lopez, S; Vigueras-Santiago, E [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados (LIDMA) Facultad de Quimica, Paseo Colon Esquina con Paseo Tollocan, s/n, CP 50000, Toluca (Mexico); Mayorga-Rojas, M; Reyes-Contreras, D, E-mail: eviguerass@uaemex.m [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico. Av. Instituto Literario 100 Ote. C. P. 50000, Toluca (Mexico)

    2009-05-01

    Changes on electrical resistivity were experimentally studied for polystyrene and carbon black-based composites respect to the temperature. 22% w/w carbon black composite films at 30{mu}m, 2mm y 1cm thick were submitted to thermal heating-cooling cycles from room temperature to 100 deg. C, slightly up to T{sub g} of the composite. For each cycle changes on electrical resistivity constituent a hysteresis loop that depends on the sample thickness. The changes during the heating stage could be explained as a consequence of the thermal expansion and mobility of the polymer chains at T{sub g}, producing a disconnecting of the electrical contacts among carbon black particles and an important increasing (200%) of the electrical resistivity. For each cycle, the hysteresis loop was observed in thicker samples, whereas for 30 mu m thickness sample the hysteresis loop was lost after four cycles.

  5. Carbon-based Composite Electrodes: Preparation, Characterization and Application in Electroanalysis

    Directory of Open Access Journals (Sweden)

    Joop Schoonman

    2007-11-01

    Full Text Available Electrodes based on carbon, i.e., expanded graphite (20%, wt.-epoxy composite(20EG-Epoxy and expanded graphite (20%, wt.-polystyrene composite (20EG-PS havebeen prepared, characterized using scanning electron microscopy (SEM and cyclicvoltammetry (CV, and tested as anodic sensors. The electrodes exhibited good mechanicalresistance and low electrical resistances. Scan rate dependent cyclic voltammetry responsesat 20EG-Epoxy and 20EG-PS composite electrodes, which were exemplified for thiourea(TU, a toxic sulphur organic compound selected as testing target analyte in 0.1 M Na2SO4 supporting electrolyte, were investigated. The obtained voltammetric data were inaccordance with those for a random array of microelectrodes. The voltammetric andchronoamperometric detection results of TU in tap water samples, without a supplementaryaddition of supporting electrolyte, at 20EG-Epoxy electrode proved its use for directanalysis of environmental samples.

  6. Creep behavior on Ag particle reinforced SnCu based composite solder joints

    Institute of Scientific and Technical Information of China (English)

    YAN Yan-fu; ZHU Jin-hong; CHEN Fu-xiao; HE Jun-guang; YANG Di-xin

    2006-01-01

    SnCu solder is one of the most promising substitutes of SnPb solder, but its creep resistance is worse than that of the other lead-free solders. Particle-reinforcement is a way to improve the creep resistance of solder alloys and cause much more attention than before. A novel Ag particles reinforced SnCu based composite solder is formed and the influence of stress on creep behavior of the composite solder is investigated. Results indicate that the creep resistance of solder joints is superior to that of the SnCu solder joints. Creep rupture lifetime of solder joints decreases gradually with stress increasing. And the creep rupture lifetime of the composite solder joints falls down faster than that of the matrix solder joints.

  7. Deformation behavior of Zr-based bulk metallic glass and composite in the supercooled liquid region

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A Zr-based bulk metallic glass (BMG) with a composition of (Zr75Cu25)78.5Ta4Ni10Al7.5 and a bulk metallic glass matrix composite (BMGC) with a composition of (Zr75Cu25)74.5Ta8Ni10Al7.5 have been prepared by copper-mold casting. The compres-sive deformation behavior of the BMG and BMGC was investigated in the super-cooled region at different temperatures and various strain rates ranging from 8×10-4s-1 to 8×10-2s-1. It was found that both the strain rate and test temperature signifi-cantly affect the deformation behavior of the two alloys. The deformation follows Newtonian flow at low strain rates but non-Newtonian flow at high strain rates. The deformation mechanism for the two kinds of alloys was discussed in terms of the transition state theory.

  8. Micromechanical modeling of damage growth in titanium based metal-matrix composites

    Science.gov (United States)

    Sherwood, James A.; Quimby, Howard M.

    1994-01-01

    The thermomechanical behavior of continuous-fiber reinforced titanium based metal-matrix composites (MMC) is studied using the finite element method. A thermoviscoplastic unified state variable constitutive theory is employed to capture inelastic and strain-rate sensitive behavior in the Timetal-21s matrix. The SCS-6 fibers are modeled as thermoplastic. The effects of residual stresses generated during the consolidation process on the tensile response of the composites are investigated. Unidirectional and cross-ply geometries are considered. Differences between the tensile responses in composites with perfectly bonded and completely debonded fiber/matrix interfaces are discussed. Model simulations for the completely debonded-interface condition are shown to correlate well with experimental results.

  9. Progressive failure analysis of composite structure based on micro- and macro-mechanics models

    Institute of Scientific and Technical Information of China (English)

    孙志刚; 阮绍明; 陈磊; 宋迎东

    2015-01-01

    Based on parameter design language, a program of progressive failure analysis in composite structures is proposed. In this program, the relationship between macro- and micro-mechanics is established and the macro stress distribution of the composite structure is calculated by commercial finite element software. According to the macro-stress, the damaged point is found and the micro-stress distribution of representative volume element is calculated by finite-volume direct averaging micromechanics (FVDAM). Compared with the results calculated by failure criterion based on macro-stress field (the maximum stress criteria and Hashin criteria) and micro-stress field (Huang model), it is proven that the failure analysis based on macro- and micro-mechanics model is feasible and efficient.

  10. Durability-Based Design Criteria for a Quasi-Isotropic Carbon-Fiber Automotive Composite

    Energy Technology Data Exchange (ETDEWEB)

    Corum, J.M.

    2002-04-17

    This report provides recommended durability-based design properties and criteria for a quasi-isotropic carbon-fiber composite for possible automotive structural applications. The composite, which was made by a rapid molding process suitable for high-volume automotive applications, consisted of continuous Thornel T300 fibers (6K tow) in a Baydur 420 IMR urethane matrix. The reinforcement was in the form of four {+-}45{sup o} stitch-bonded mats in the following layup: [0/90{sup o}/{+-}45{sup o}]{sub S}. This material is the second in a progression of three candidate thermoset composites to be characterized and modeled as part of an Oak Ridge National Laboratory project entitled Durability of Carbon-Fiber Composites. The overall goal of the project, which is sponsored by the U.S. Department of Energy's Office of Advanced Automotive Technologies and is closely coordinated with the industry Automotive Composites Consortium, is to develop durability-driven design data and criteria to assure the long-term integrity of carbon-fiber-based composite systems for large automotive structural components. This document is in two parts. Part I provides the design criteria, and Part 2 provides the underlying experimental data and models. The durability issues addressed include the effects on deformation, strength, and stiffness of cyclic and sustained loads, operating temperature, automotive fluid environments, and low-energy impacts (e.g., tool drops and kickups of roadway debris). Guidance is provided for design analysis, time-dependent allowable stresses, rules for cyclic loadings, and damage tolerance design guidance, including the effects of holes. Chapter 6 provides a brief summary of the design criteria.

  11. Colorimetric humidity sensor based on liquid composite materials for the monitoring of food and pharmaceuticals.

    Science.gov (United States)

    Bridgeman, Devon; Corral, Javier; Quach, Ashley; Xian, Xiaojun; Forzani, Erica

    2014-09-01

    Using supported ionic-liquid membrane (SILM)-inspired methodologies, we have synthesized, characterized, and developed a humidity sensor by coating a liquid composite material onto a hygroscopic, porous substrate. Similar to pH paper, the sensor responds to the environment's relative humidity and changes color accordingly. The humidity indicator is prepared by casting a few microliters of low-toxicity reagents on a nontoxic substrate. The sensing material is a newly synthesized liquid composite that comprises a hygroscopic medium for environmental humidity capture and a color indicator that translates the humidity level into a distinct color change. Sodium borohydride was used to form a liquid composite medium, and DenimBlu30 dye was used as a redox indicator. The liquid composite medium provides a hygroscopic response to the relative humidity, and DenimBlu30 translates the chemical changes into a visual change from yellow to blue. The borate-redox dye-based humidity sensor was prepared, and then Fourier transform infrared spectroscopy, differential scanning calorimetry, and image analysis methods were used to characterize the chemical composition, optimize synthesis, and gain insight into the sensor reactivity. Test results indicated that this new sensing material can detect relative humidity in the range of 5-100% in an irreversible manner with good reproducibility and high accuracy. The sensor is a low-cost, highly sensitive, easy-to-use humidity indicator. More importantly, it can be easily packaged with products to monitor humidity levels in pharmaceutical and food packaging. PMID:25141132

  12. Tannin-based flax fibre reinforced composites for structural applications in vehicles

    International Nuclear Information System (INIS)

    Innovation is often driven by changes in government policies regulating the industries, especially true in case of the automotive. Except weight savings, the strict EU regulation of 95% recyclable material-made vehicles drives the manufactures and scientists to seek new 'green materials' for structural applications. With handing at two major drawbacks (production cost and safety), ECHOSHELL is supported by EU to develop and optimise structural solutions for superlight electric vehicles by using bio-composites made of high-performance natural fibres and resins, providing enhanced strength and bio-degradability characteristics. Flax reinforced tannin-based composite is selected as one of the candidates and were firstly investigated with different fabric lay-up angles (non-woven flax mat, UD, [0, 90°]4 and [0, +45°, 90°, −45°]2) through authors' work. Some of the obtained results, such as tensile properties and SEM micrographs were shown in this conference paper. The UD flax reinforced composite exhibits the best tensile performance, with tensile strength and modulus of 150 MPa and 9.6 MPa, respectively. It was observed that during tension the oriented-fabric composites showed some delamination process, which are expected to be eliminated through surface treatment (alkali treatment etc.) and nanotechnology, such as the use of nano-fibrils. Failure mechanism of the tested samples were identified through SEM results, indicating that the combination of fibre pull-out, fibre breakage and brittle resins failure mainly contribute to the fracture failure of composites.

  13. Evaluation of embedded FBGs in composite overwrapped pressure vessels for strain based structural health monitoring

    Science.gov (United States)

    Pena, Francisco; Strutner, Scott M.; Richards, W. Lance; Piazza, Anthony; Parker, Allen R.

    2014-03-01

    The increased use of composite overwrapped pressure vessels (COPVs) in space and commercial applications, and the explosive nature of pressure vessel ruptures, make it crucial to develop techniques for early condition based damage detection. The need for a robust health monitoring system for COPVs is a high priority since the mechanisms of stress rupture are not fully understood. Embedded Fiber Bragg Grating (FBG) sensors have been proposed as a potential solution that may be utilized to anticipate and potentially avoid catastrophic failures. The small size and light weight of optical fibers enable manufactures to integrate FBGs directly into composite structures for the purpose of structural health monitoring. A challenging aspect of embedding FBGs within composite structures is the risk of potentially impinging the optical fiber while the structure is under load, thus distorting the optical information to be transferred. As the COPV is pressurized, an embedded optical sensor is compressed between the expansion of the inner bottle, and the outer overwrap layer of composite. In this study, FBGs are installed on the outer surface of a COPV bottle as well as embedded underneath a composite overwrap layer for comparison of strain measurements. Experimental data is collected from optical fibers containing multiple FBGs during incremental pressurization cycles, ranging from 0 to 10,000 psi. The graphical representations of high density strain maps provide a more efficient process of monitoring structural integrity. Preliminary results capture the complex distribution of strain, while furthering the understanding of the failure mechanisms of COPVs.

  14. Composites based on PET and red mud residues as catalyst for organic removal from water.

    Science.gov (United States)

    Bento, Natálya I; Santos, Patrícia S C; de Souza, Talita E; Oliveira, Luiz C A; Castro, Cínthia S

    2016-08-15

    In this study, we obtained a composite based on carbon/iron oxide from red mud and PET (poly(ethylene terephthalate)) wastes by mechanical mixture (10, 15 and 20wt.% of PET powder/red mud) followed by a controlled thermal treatment at 400°C under air. XRD analyses revealed that the α-Fe2O3 is the main phase formed from red mud. TPR analyses showed that the iron oxide present in the composites undergoes reduction at lower temperature to form Fe(2+) species present in Fe3O4, indicating that the iron oxide in the composite can exhibit greater reactivity in the catalytic processes compared to the original red mud. In fact, catalytic tests showed that the composites presented higher capacity to remove methylene blue dye (MB), presenting about 90% of removal after 24h of reaction. The MB removal was also monitored by mass spectrometer with ionization via electrospray (ESI-MS), which demonstrated the occurrence of the oxidation process, showing the formation of MB oxidation products. The stability of the composites was confirmed after four reuse cycles. The results seem to indicate that PET carbon deposited over the iron oxide from red mud promotes adsorption of the contaminant allowing its contact with the iron atoms and their consequent reaction.

  15. Tannin-based flax fibre reinforced composites for structural applications in vehicles

    Science.gov (United States)

    Zhu, J.; Abhyankar, H.; Nassiopoulos, E.; Njuguna, J.

    2012-09-01

    Innovation is often driven by changes in government policies regulating the industries, especially true in case of the automotive. Except weight savings, the strict EU regulation of 95% recyclable material-made vehicles drives the manufactures and scientists to seek new 'green materials' for structural applications. With handing at two major drawbacks (production cost and safety), ECHOSHELL is supported by EU to develop and optimise structural solutions for superlight electric vehicles by using bio-composites made of high-performance natural fibres and resins, providing enhanced strength and bio-degradability characteristics. Flax reinforced tannin-based composite is selected as one of the candidates and were firstly investigated with different fabric lay-up angles (non-woven flax mat, UD, [0, 90°]4 and [0, +45°, 90°, -45°]2) through authors' work. Some of the obtained results, such as tensile properties and SEM micrographs were shown in this conference paper. The UD flax reinforced composite exhibits the best tensile performance, with tensile strength and modulus of 150 MPa and 9.6 MPa, respectively. It was observed that during tension the oriented-fabric composites showed some delamination process, which are expected to be eliminated through surface treatment (alkali treatment etc.) and nanotechnology, such as the use of nano-fibrils. Failure mechanism of the tested samples were identified through SEM results, indicating that the combination of fibre pull-out, fibre breakage and brittle resins failure mainly contribute to the fracture failure of composites.

  16. A single-level composite structure optimization method based on a blending tapered model

    Institute of Scientific and Technical Information of China (English)

    An Weigang; Chen Dianyu; Jin Peng

    2013-01-01

    In order to decrease the number of design variables and improve the efficiency of composite structure optimal design,a single-level composite structure optimization method based on a tapered model is presented.Compared with the conventional multi-level composite structure optimization method,this single-level method has many advantages.First,by using a distance variable and a ply group variable,the number of design variables is decreased evidently and independent with the density of sub-regions,which makes the single-level method very suitable for large-scale composite structures.Second,it is very convenient to optimize laminate thickness and stacking sequence in the same level,which probably improves the quality of optimal result.Third,ply continuity can be guaranteed between sub-regions in the single-level method,which could reduce stress concentration and manufacturing difficulty.An example of a composite wing is used to demonstrate the advantages and competence of the single-level method proposed.

  17. Composites based on PET and red mud residues as catalyst for organic removal from water.

    Science.gov (United States)

    Bento, Natálya I; Santos, Patrícia S C; de Souza, Talita E; Oliveira, Luiz C A; Castro, Cínthia S

    2016-08-15

    In this study, we obtained a composite based on carbon/iron oxide from red mud and PET (poly(ethylene terephthalate)) wastes by mechanical mixture (10, 15 and 20wt.% of PET powder/red mud) followed by a controlled thermal treatment at 400°C under air. XRD analyses revealed that the α-Fe2O3 is the main phase formed from red mud. TPR analyses showed that the iron oxide present in the composites undergoes reduction at lower temperature to form Fe(2+) species present in Fe3O4, indicating that the iron oxide in the composite can exhibit greater reactivity in the catalytic processes compared to the original red mud. In fact, catalytic tests showed that the composites presented higher capacity to remove methylene blue dye (MB), presenting about 90% of removal after 24h of reaction. The MB removal was also monitored by mass spectrometer with ionization via electrospray (ESI-MS), which demonstrated the occurrence of the oxidation process, showing the formation of MB oxidation products. The stability of the composites was confirmed after four reuse cycles. The results seem to indicate that PET carbon deposited over the iron oxide from red mud promotes adsorption of the contaminant allowing its contact with the iron atoms and their consequent reaction. PMID:27149399

  18. The Effect of Hydrogen Peroxide 35% on Surface Roughness of Silorane and Methacrylate Based Composites

    Directory of Open Access Journals (Sweden)

    L. Rezaei Sofi

    2015-04-01

    Full Text Available Introduction & Objectives: Surface roughness affects beauty, hygiene, plaque retention and health of the gingival adjacent to the composite restoration. Many people use bleaching agents to beautify their teeth that may lead to changes in surface roughness. This study was designed to compare the silorane and methacrylate-based composites in bleached teeth. Materials & Methods: In this experimental study 48 composite resin disks were prepared and divided into 4 groups: P90, Z250, Z250XT and Z350XT (n=12. To determine the surface roughness, surface profile measurement of the samples was performed using profilometer. Samples of each diet group underwent 35% hydrogen peroxide in office whitening (Hpmax in three 45-minute sessions one week apart. The secondary instances of surface profile was then measured. The data collected by the Kolmogorov-Smirnov test, one-way ANOVA, Tukey test and paired t- test at a significance level of 0.05 were analyzed using spss16. Results: There was a significant difference (P<0.05 in the surface roughness after bleaching on composite Z350XT with P90 and Z350XT with Z250. The surface roughness of all groups before and after bleaching showed a significant difference (P<0.05. Conclusion: The use of hydrogen peroxide 35% causes a significant increase in the surface roughness of composite P90, Z250, Z250XT and Z350XT. (Sci J Hamadan Univ Med Sci 2015; 22 (1:23-29

  19. Immobilization and Bioelectrochemistry of Hemoglobin Based on Carrageenan and Room Temperature Ionic Liquid Composite Film

    Institute of Scientific and Technical Information of China (English)

    盛春; 张洋; 王璐; 贾能勤

    2012-01-01

    A novel biopolymer/room-temperature ionic liquid composite film based on carrageenan, room temperature ionic liquid (IL) [1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4)] was explored for immobilization of hemoglobin (Hb) and construction of biosensor. Direct electrochemistry and electrocatalytic behaviors of Hb entrapped in the IL-carrageenan composite film on the surface of glassy carbon electrode (GCE) were investigated. UV-vis spectroscopy demonstrated that Hb in the IL-carrageenan composite film could retain its native secondary structure. A pair of well-defined redox peaks of Hb was obtained at the Hb-IL-carrageenan composite film modified electrode through direct electron transfer between the protein and the underlying electrode. The heterogeneous electron transfer rate constant (ks) was 2.02 s 1, indicating great facilitation of the electron transfer between Hb and IL-carrageenan composite film modified electrode. The modified electrode showed excellent electrocatalytic activity toward reduction of hydrogen peroxide with a linear range of 5.0 × 10-6 to 1.5 ×10-4 mol/L and the detection limit was 2.12 ×10 7 mol/L (S/N= 3). The apparent Michaelis-Menten constant KM^app for hydrogen peroxide was estimated to be 0.02 mmol/L, indicating that the biosensor possessed high affinity to hydrogen peroxide. In addition, the proposed biosensor showed good reproducibility and stability.

  20. Fiber optic humidity sensor based on the graphene oxide/PVA composite film

    Science.gov (United States)

    Wang, Youqing; Shen, Changyu; Lou, Weimin; Shentu, Fengying

    2016-08-01

    Fiber optic humidity sensor based on an in-fiber Mach-Zehnder interferometer (MZI) coated with graphene oxide (GO)/PVA composite film was investigated. The MZI is constructed of two waist-enlarged tapers. The length between two waist-enlarged tapers is 20 mm. By comparing the experiment results of MZI coated with different GO/PVA composite films, composite film formed by the ratio of 0.3 g PVA mixed with 10 ml GO dispersion shows a better performance of relative humidity sensing. By using the molecular structure model of the composited GO/PVA, the operation mechanism between GO/PVA composite film and water molecules was illustrated. The sensitivity of 0.193 dB/%RH with a linear correlation coefficient of 99.1% and good stability under the relative humidity range of 25-80% was obtained. Temperature effect on the proposed fiber optic humidity sensor was also considered and analyzed. According to the repetitive experimental results, the proposed humidity sensor shows a good repeatability.

  1. Composite material based on an ablative phenolic resin and carbon fibers

    Directory of Open Access Journals (Sweden)

    DIMKO DIMESKI

    2009-04-01

    Full Text Available In this study, a technological procedure for the production of a molding compound based on short carbon fibers and an ablative phenol–formaldehyde resin for high temperature application was optimized. The starting raw materials were characterized and molding compounds with different fiber/matrix ratios and different fiber lengths were obtained. From the different laboratory samples, molded parts were made by thermocompression. The basic mechanical and thermal properties of the composites were determined. From the obtained results, the optimal fiber/matrix ratio was determined for a production of molding compound for high temperature application. The molding process of the composite material was optimized and all the parameters for good mechanical properties and high thermal stability of the composite were obtained. Optimization of the composite molding process was performed by the application of a numerical method for a planned experiment, i.e., a full three-factorial experimental design with variance of all three parameters (fiber length, temperature and time of the press cycle on two levels. The obtained mechanical properties (flexural strength: 247 MPa, modulus: 27.6 GPa, impact resistance: 110 (for test moldings 10 mm´10 mm and 91 kJ/m2 (for test moldings 15 mm´15 mm justified the application of this composite material in the automotive, leisure, military and other industries where high temperature resistance and high mechanical strength is required.

  2. Sustainable, heat-resistant and flame-retardant cellulose-based composite separator for high-performance lithium ion battery

    OpenAIRE

    Jianjun Zhang; Liping Yue; Qingshan Kong; Zhihong Liu; Xinhong Zhou; Chuanjian Zhang; Quan Xu; Bo Zhang; Guoliang Ding; Bingsheng Qin; Yulong Duan; Qingfu Wang; Jianhua Yao; Guanglei Cui; Liquan Chen

    2014-01-01

    A sustainable, heat-resistant and flame-retardant cellulose-based composite nonwoven has been successfully fabricated and explored its potential application for promising separator of high-performance lithium ion battery. It was demonstrated that this flame-retardant cellulose-based composite separator possessed good flame retardancy, superior heat tolerance and proper mechanical strength. As compared to the commercialized polypropylene (PP) separator, such composite separator presented impro...

  3. Role of polyvinyl alcohol in the conductivity behaviour of polyethylene glycol-based composite gel electrolytes

    Indian Academy of Sciences (India)

    S K Patel; R B Patel; A Awadhia; N Chand; S L Agrawal

    2007-09-01

    An attempt has been made in the present work to combine gel and composite polymer electrolyte routes together to form a composite polymeric gel electrolyte that is expected to possess high ionic conductivity with good mechanical integrity. Polyethylene glycol (PEG) based composite gel electrolytes using polyvinyl alcohol (PVA) as guest polymer have been synthesized with 1 molar solution of ammonium thiocyanate (NH4SCN) in dimethyl sulphoxide (DMSO) and electrically characterized. The ionic conductivity measurements indicate that PEG : PVA : NH4SCN-based composite gel electrolytes are superior (max = 5.7 × 10−2 S cm-1) to pristine electrolytes (PEG : NH4SCN system) and conductivity variation with filler concentration remains within an order of magnitude. The observed conductivity maxima have been correlated to PEG : PVA : NH4SCN- and PVA : NH4SCN-type complexes. Temperature dependence of conductivity profiles exhibits Arrhenius behaviour in low temperature regime followed by VTF character at higher temperature.

  4. Effectiveness of composition based on oxidized dextran in the treatment of grade IIIB skin burns.

    Science.gov (United States)

    Shkurupy, V A; Karpov, M A; Troitskii, A V; Arkhipov, S A; Neshchadim, D V

    2015-03-01

    Grade IIIB skin burns were treated with a composition based on oxidized dextran with a molecular weight of 40 kDa (oxidation of 7% glucose residues). On day 32 after burn infliction and from the start of the treatment, the area of skin defect in rats was 30% less than in the group without treatment and by 2.3 times less than in rats treated with panthenol. In rats treated with dextran-based composition or panthenol, the eschar was absent on day 21 after the start of the treatment; by day 32, we found cells of surface epithelium, hair follicles, and sebaceous glands above the scar tissue that were absent in untreated animals; in rats treated with the composition, their number was higher by 2.5 times than in animals treated with panthenol. Treatment with the composition increased volume density (by 2.5 times) and numerical density (by more than 3 times) of blood vessels in the wound and reduced signs of inflammation and fibroplastic activity of fibroblasts in comparison with the corresponding parameters in untreated animals or animals treated with panthenol. PMID:25778648

  5. Geometric optimization of a neutron detector based on a lithium glass–polymer composite

    International Nuclear Information System (INIS)

    We report on the simulation and optimization of a neutron detector based on a glass–polymer composite that achieves high gamma rejection. Lithium glass is embedded in polyvinyltoluene in three geometric forms: disks, rods, and spheres. Optimal shape, geometric configuration, and size of the lithium glass fragments are determined using Geant4 simulations. All geometrical configurations maintain an approximate 7% glass to polymer mass ratio. Results indicate a 125-mm diameter as the optimal detector size for initial prototype design achieving a 10% efficiency for the thermalization of incident fission neutrons from 252Cf. The geometrical features of a composite detector are shown to have little effect on the intrinsic neutron efficiency, but a significant effect on the gamma rejection is observed. The sphere geometry showed the best overall performance with an intrinsic neutron efficiency of approximately 6% with a gamma rejection better than 10−7 for 280-μm diameter spheres. These promising results provide a motivation for prototype composite detector development based on the simulated designs. - Highlights: • Composite polymer–lithium glass scintillation detector is simulated. • Polymer is considered to be non-scintillating in the simulation. • Three forms of lithium glass are considered: disks, rods, and spheres. • Glass shape has a small effect on neutron efficiency. • Glass shape has a significant effect on gamma rejection

  6. Effect of Nano Cr2O3 in HTPB/AP/Al Based Composite Propellant Formulations

    Directory of Open Access Journals (Sweden)

    Dhirendra Kshirsagar

    2016-03-01

    Full Text Available Different compositions have been prepared by incorporating nano sized chromium oxide from 0.25 % to 1 % in HTPB/AP/Al based composite propellant formulation having 86% of solid loading and studied its effect on viscosity build-up, thermal, mechanical and ballistic properties. The findings reveal that on increasing the percentage of nano Cr2O3 in the composition, there is an increase in end of mix viscosity, elastic modulus and tensile strength while elongation decreases accordingly. The data on thermal properties envisage the reduction in thermal decomposition temperature of ammonium perchlorate as well as formulations based on HTPB/AP/Al. The data on ballistic properties reveal that there is an enhancement in burning rate from 6.11 mm/s to 7.88 mm/s at 6.86 MPa, however, marginal increase in  pressure exponent (‘n’ values from 0.35 to 0.53 with 1 wt % of nano Cr2O3 was observed  in comparison to reference composition without chromium oxide. Defence Science Journal, Vol. 66, No. 2, March 2016, pp. 100-106, DOI: http://dx.doi.org/10.14429/dsj.66.9250

  7. Geometric optimization of a neutron detector based on a lithium glass–polymer composite

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, M., E-mail: mike.f.mayer@gmail.com [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Nattress, J. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Trivelpiece, C. [Materials Research Institute, The Pennsylvania State University, University Park, PA 16802 (United States); Jovanovic, I. [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States)

    2015-06-01

    We report on the simulation and optimization of a neutron detector based on a glass–polymer composite that achieves high gamma rejection. Lithium glass is embedded in polyvinyltoluene in three geometric forms: disks, rods, and spheres. Optimal shape, geometric configuration, and size of the lithium glass fragments are determined using Geant4 simulations. All geometrical configurations maintain an approximate 7% glass to polymer mass ratio. Results indicate a 125-mm diameter as the optimal detector size for initial prototype design achieving a 10% efficiency for the thermalization of incident fission neutrons from {sup 252}Cf. The geometrical features of a composite detector are shown to have little effect on the intrinsic neutron efficiency, but a significant effect on the gamma rejection is observed. The sphere geometry showed the best overall performance with an intrinsic neutron efficiency of approximately 6% with a gamma rejection better than 10{sup −7} for 280-μm diameter spheres. These promising results provide a motivation for prototype composite detector development based on the simulated designs. - Highlights: • Composite polymer–lithium glass scintillation detector is simulated. • Polymer is considered to be non-scintillating in the simulation. • Three forms of lithium glass are considered: disks, rods, and spheres. • Glass shape has a small effect on neutron efficiency. • Glass shape has a significant effect on gamma rejection.

  8. Damage detection tomography based on guided waves in composite structures using a distributed sensor network

    Science.gov (United States)

    Memmolo, Vittorio; Maio, Leandro; Boffa, Natalino Daniele; Monaco, Ernesto; Ricci, Fabrizio

    2016-01-01

    Structural health monitoring (SHM) based on guided waves allows assessing the health of a structure due to the sensitivity to the occurrence of delamination. However, wave propagation presents several complexities for effective damage identification in composite structures. An efficient implementation of a guided wave-based SHM system requires an accurate analysis of collected data to obtain a useful detection. This paper is concerned with the identification of small emerging delaminations in composite structural components using a sparse array of surface ultrasonic transducers. An ultrasonic-guided wave tomography technique focused on impact damage detection in composite plate-like structures is presented. A statistical damage index approach is adopted to interpret the recorded signals, and a subsequent graphic interpolation is implemented to reconstruct the damage appearance. Experimental tests carried out on a typical composite structure demonstrated the effectiveness of the developed technique with the aim to investigate the presence and location of damage using simple imaging reports and a limited number of measurements. A traditional ultrasonic inspection (C-scan) is used to assess the methodology.

  9. Preparation and characterization of Co/PAN-based carbon fibrous composites

    Science.gov (United States)

    Zhixin, J.; Yongyi, Y.; Gang, J.

    2011-07-01

    The cobalt/polyacrylonitrile (Co/PAN)-based carbon fibrous composites were prepared. The PAN incorporated with cobalt ions was in situ polymerized by initiating the complex solution of acrylonitrile (AN)/cobalt (II) chloride (CoCl2) in which the contents of cobalt ions were 0 wt.%, 0.29 wt.%, 0.56 wt.% and 1.14 wt.%, respectively. The ultrathin blue fibers were formed from the cobalt/PAN composites by the electrospinning method. The electrospun cobalt-incorporated PAN fibers were successfully stabilized in air and subsequently carbonized to form the carbon fibrous composites in a nitrogen (N2) atmosphere. Based on the scanning electron microscopy (SEM), we noticed that beads and beaded fibers were produced during the electrospinning process. When the content of cobalt ions in the complex solution was as high as 1.14 wt.%, there were many honeycomb-like structures and nanopores formed in both stabilized and carbonized fibers. The X-ray photoelectron spectra (XPS) were used to characterize the structure of the composite fibers.

  10. The Tribological Efficiency and the Mechanism of Action of Nano-Porous Composition Base Brake Lining Materials

    Science.gov (United States)

    Kutelia, E. R.; Gventsadze, D. I.; Eristavil, B. G.; Maisuradze, N. I.; Tsurtsumia, O. O.; Gventsadze, L. D.; Olofsson, U.; Wahlström, J.; Olander, L.

    2011-12-01

    Based on the comparative analysis of the experimental values determined for the tribological parameters for the three novel nano-porous composition base and two conventional brake lining materials while friction with the grey cast iron disc, it was shown the considerable high tribological efficiency of the novel nano-porous composition base lining materials in comparison with the conventional (from EU and USA market) brake lining materials. The explanation is given to the action mechanism of nano-porous composition base brake lining material and its tribological efficiency basing on the "triple phase" tribo-pair model.

  11. Support for Dynamic Service Composition with Role-Based Interaction Model

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper aims to present a role-based interaction model for dynamic service composition in Grid environments. Assigning roles to a service means to associate with it capabilities that describes all the operations the service intends to perform. When all of the services can be recognized by their roles, the appropriate services can be selected. Based on the interaction policy, a role-based interaction model not only facilitates access control, but also offers flexible interaction mechanism for adapting service-oriented applications. This interaction model adopts programmable reactive tuple space to facilitate context-dependent coordination.

  12. PbO2 based composite materials deposited from suspension electrolytes: electrosynthesis, physico-chemical and electrochemical properties

    OpenAIRE

    Velichenko, Alexander; Knysh, Valentina; Luk’yanenko, Tatiana; Dmitrikova, Larisa; Velichenko, Yulia; Devilliers, Didier

    2012-01-01

    Composite materials based on PbO2 containing TiO2 or ZrO2 were prepared from electrolytes containing a suspension of TiO2 or ZrO2. The contents of foreign oxides in the composite depend on the electrolyte composition and conditions of deposition. When a dispersed phase is incorporated into the composite coating, the dimensions of lead dioxide crystals decrease to submicro- and nano-size. Physico-chemical properties and electrocatalytic activity of composite materials are mainly determin...

  13. Quantitative analysis of mutation and selection pressures on base composition skews in bacterial chromosomes

    Directory of Open Access Journals (Sweden)

    Chen Carton W

    2007-08-01

    Full Text Available Abstract Background Most bacterial chromosomes exhibit asymmetry of base composition with respect to leading vs. lagging strands (GC and AT skews. These skews reflect mainly those in protein coding sequences, which are driven by asymmetric mutation pressures during replication and transcription (notably asymmetric cytosine deamination plus subsequent selection for preferred structures, signals, amino acid or codons. The transcription-associated effects but not the replication-associated effects contribute to the overall skews through the uneven distribution of the coding sequences on the leading and lagging strands. Results Analysis of 185 representative bacterial chromosomes showed diverse and characteristic patterns of skews among different clades. The base composition skews in the coding sequences were used to derive quantitatively the effect of replication-driven mutation plus subsequent selection ('replication-associated pressure', RAP, and the effect of transcription-driven mutation plus subsequent selection at translation level ('transcription-associate pressure', TAP. While different clades exhibit distinct patterns of RAP and TAP, RAP is absent or nearly absent in some bacteria, but TAP is present in all. The selection pressure at the translation level is evident in all bacteria based on the analysis of the skews at the three codon positions. Contribution of asymmetric cytosine deamination was found to be weak to TAP in most phyla, and strong to RAP in all the Proteobacteria but weak in most of the Firmicutes. This possibly reflects the differences in their chromosomal replication machineries. A strong negative correlation between TAP and G+C content and between TAP and chromosomal size were also revealed. Conclusion The study reveals the diverse mutation and selection forces associated with replication and transcription in various groups of bacteria that shape the distinct patterns of base composition skews in the chromosomes during

  14. Damage detection in composite structures based on optical fibre strain sensing and finite element model updating

    Energy Technology Data Exchange (ETDEWEB)

    Nosenzo, G.; Dalton, T. [Stokes Research Inst., Univ. of Limerick, Limerick (Ireland); Whelan, M.P. [European Commission Joint Research Centre, Ispra (Italy)

    2003-07-01

    A prototype system for condition monitoring of composite structures is described that relies on the on-line measurement of dynamic strains in order to detect any deterioration in performance due to the accumulation of damage. Strain data from both long gauge and point optical fibre sensors are employed to update finite element models of the analysed structures. Together with Bragg grating point sensors, an innovative Fabry-Perot interferometric long gauge strain sensor is proposed. The cavity of these sensors consists of a pair of matched Bragg grating reflectors allowing a number of sensors of the desired length to be wavelength multiplexed on a single fibre, with the advantage of minimum intrusivity in composite materials while retaining sensing capability over the whole structure. A heterodyne based demodulation system, tailored for these sensors, has been employed. Gradient based optimisation algorithms have been utilised to update structural Finite Elements models based on the output from the fibre optic sensors and strain based modal analyses. These procedures were used to detect the location of areas with known modifications of the stiffness properties in composite structures and showed good results, as the damaged areas have been correctly located. The comparison with results obtained using more conventional updating techniques shows the validity of the dynamic strain data approach in the damage detection field. (orig.)

  15. Wear Characteristics of Hybrid Composites Based on Za27 Alloy Reinforced With Silicon Carbide and Graphite Particles

    Directory of Open Access Journals (Sweden)

    S. Mitrović

    2014-06-01

    Full Text Available The paper presents the wear characteristics of a hybrid composite based on zinc-aluminium ZA27 alloy, reinforced with silicon-carbide and graphite particles. The tested sample contains 5 vol.% of SiC and 3 vol.% Gr particles. Compocasting technique has been used to prepare the samples. The experiments were performed on a “block-on-disc” tribometer under conditions of dry sliding. The wear volumes of the alloy and the composite were determined by varying the normal loads and sliding speeds. The paper contains the procedure for preparation of sample composites and microstructure of the composite material and the base ZA27 alloy. The wear surface of the composite material was examined using the scanning electronic microscope (SEM and energy dispersive spectrometry (EDS. Conclusions were obtained based on the observed impact of the sliding speed, normal load and sliding distance on tribological behaviour of the observed composite.

  16. Water Uptake Behavior and Young Modulus Prediction of Composites Based on Treated Sisal Fibers and Poly(Lactic Acid

    Directory of Open Access Journals (Sweden)

    Ander Orue

    2016-05-01

    Full Text Available The main aim of this work was to study the effect of sisal fiber surface treatments on water uptake behavior of composites based on untreated and treated fibers. For this purpose, sisal fibers were treated with different chemical treatments. All surface treatments delayed the water absorption of fibers only for a short time of period. No significant differences were observed in water uptake profiles of composites based on fibers with different surface treatments. After water uptake period, tensile strength and Young modulus values of sisal fiber/poly(lactic acid (PLA composites were decreased. On the other hand, composites based on NaOH + silane treated fibers showed the lowest diffusion coefficient values, suggesting that this treatment seemed to be the most effective treatment to reduce water diffusion rate into the composites. Finally, Young modulus values of composites, before water uptake period, were predicted using different micromechanical models and were compared with experimental data.

  17. Effect of curing temperature on flexural properties of silica-based geopolymer-carbon reinforced composite

    Directory of Open Access Journals (Sweden)

    D.H. Tran

    2009-12-01

    Full Text Available Purpose: The aim of this paper is to find out the curing temperature at which we can achieve the best mechanical properties and adhesion between silica-based geopolymer matrix (Q1 and carbon HTS 5631 1600tex 24K fibre.Design/methodology/approach: The carbon fibre was impregnated with silica-based geopolymer by means of home-made “impregnation machine”. This equipment was designed based on simulating the real pultrusion or filament winding technique. Composite samples were made manually in silicon mould and cured under hot vacuum bagging technique at different temperatures. Flexural properties were determined under three-point bending mode in accordance with British Standard BS EN ISO 14125:1998. The sections perpendicular to fibres and surfaces of the composites were analysed by means of scanning electron microscope (SEM to estimate the adhesion between geopolymer matrices and fibre reinforcement.Findings: Relatively wide range of curing temperature from 70oC to 100oC at which we can obtain high flexural properties, maximal values of flexural strength 570 MPa, flexural modulus 65 GPa and relative deformation of composite was 0.98% when the composite was cured and dried at 75oC. Adhesion of the geopolymer matrix to carbon fibre was very good and hardly to determine the differences by SEM image observation within the range of optimal curing temperature.Research limitations/implications: The curing time was too long to provide the geopolymerization process before it had been completed, this factor caused that it should be carried out in the future and we may use liquid absorption to determine how many cavities are in the composites.Practical implications: The research presents original information on the influence of different curing temperatures on mechanical properties and micro-structure of silica-based geopolymer matrix – carbon composite. The results are useful for further investigations.Originality/value: Determining the optimal curing

  18. Constitutive modeling of two-phase metallic composites with application to tungsten-based composite 93W–4.9Ni–2.1Fe

    Energy Technology Data Exchange (ETDEWEB)

    Lu, W.R.; Gao, C.Y., E-mail: lxgao@zju.edu.cn; Ke, Y.L.

    2014-01-13

    The two-phase metallic composites, composed by the metallic particulate reinforcing phase and the metallic matrix phase, have attracted a lot of attention in recent years for their excellent material properties. However, the constitutive modeling of two-phase metallic composites is still lacking currently. Most used models for them are basically oriented for single-phase homogeneous metallic materials, and have not considered the microstructural evolution of the components in the composite. This paper develops a new constitutive model for two-phase metallic composites based on the thermally activated dislocation motion mechanism and the volume fraction evolution. By establishing the relation between microscopic volume fraction and macroscopic state variables (strain, strain rate and temperature), the evolution law of volume fraction during the plastic deformation in two-phase composites is proposed for the first time and introduced into the new model. Then the new model is applied to a typical two-phase tungsten-based composite – 93W–4.9Ni–2.1Fe tungsten heavy alloy. It has been found that our model can effectively describe the plastic deformation behaviors of the tungsten-based composite, because of the introduction of volume fraction evolution and the connecting of macroscopic state variables and micromechanical characteristics in the constitutive model. The model's validation by experimental data indicates that our new model can provide a satisfactory prediction of flow stress for two-phase metallic composites, which is better than conventional single-phase homogeneous constitutive models including the Johnson–Cook (JC), Khan–Huang–Liang (KHL), Nemat-Nasser–Li (NNL), Zerilli–Armstrong (ZA) and Voyiadjis–Abed (VA) models.

  19. Mechanistic aspects of fracture and fatigue in resin based dental restorative composites

    Science.gov (United States)

    Shah, Minalben B.

    For resin based dental restorative composites, one of the major challenges is to optimize the balance between mechanical and optical properties. Although fracture is the second leading cause of dental restorative failures, very limited mechanistic understanding exists on a microscopic level. In the present study, the fracture properties and mechanisms of two commercial dental resin composites with different microstructures are examined using double notched four point beam bending and pre-cracked compact-tension, C(T), specimens. Four point bend flexural strength was also measured using un-notched beam samples. The first material is a microhybrid composite that combines a range of nano and micro scale filler particles to give an average particle size of 0.6 mum, while the second is a nanofill composite reinforced entirely with nano particles and their agglomerates. The influences of 60 days water hydration and a post-cure heat treatment were also examined. Fracture resistance curve (R-curve) experiments have demonstrated the microhybrid composite to be more fracture resistant than the nanofill composite in both as-processed and hydrated conditions. Rising fracture resistance with crack extension was observed in all specimens, independent of the environmental conditions. Compared to the as-processed condition, a significant reduction in the peak toughness was observed for the nanofill composite after 60 days of water aging. Hydration lowered flexural strength of both composites which was attributed to hydrolytic matrix degradation with additional interfacial debonding causing larger strength decrease in the nanofill. Optical and SEM observations revealed an interparticle matrix crack path promoting crack deflection as a toughening mechanism in all cases except the hydrated nanofill which showed particle-matrix debonding. Crack bridging was another observed extrinsic toughening mechanism that was believed to be responsible for the rising fracture resistance curve (R

  20. Enhanced photoelectrochemical sensor based on ZnO–SnO{sub 2} composite nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    An, Xiuyun; Teng, Feng; Zhang, Peng; Zhao, Changhui; Pan, Xiaojun; Zhang, Zhenxing, E-mail: zhangzx@lzu.edu.cn; Xie, Erqing, E-mail: xieeq@lzu.edu.cn

    2014-11-25

    Highlights: • Composite nanotubes were used in photoelectrochemical (PEC) H{sub 2}O{sub 2} sensor. • It is the first time to use semiconductor composite as PEC biosensor. • ZnO–SnO{sub 2} nanotubes electrode performs better PEC property than SnO{sub 2} nanotubes electrode. - Abstract: Composite nanotubes modified electrodes with enhanced photoelectrochemical (PEC) performance have great potentialities in biological systems monitoring and detection. In this paper ZnO–SnO{sub 2} and SnO{sub 2} nanotubes were prepared by electrospinning. The results show that the visible light emission intensity of ZnO–SnO{sub 2} composite nanotubes is much higher than that of SnO{sub 2} nanotubes, indicating the existence of large amount of oxygen defects in ZnO–SnO{sub 2} nanotubes. Photocurrent response of SnO{sub 2} nanotubes electrode to hydrogen peroxide (H{sub 2}O{sub 2}) randomly increases with increased H{sub 2}O{sub 2} concentration. While the dark current and photocurrent of ZnO–SnO{sub 2} nanotubes electrode decrease exponentially and linearly, respectively. Moreover, ZnO–SnO{sub 2} nanotubes electrode appears more outstanding H{sub 2}O{sub 2} sensing capability than pure SnO{sub 2} nanotubes electrode under UV radiation. These can be well clarified by electron transfer mechanism in ZnO–SnO{sub 2} nano-composite. Different reactions on SnO{sub 2} and ZnO–SnO{sub 2} surface have been explained in details based on PEC performances of the two modified electrodes. This facile strategy extends the application of semiconductor composite for monitoring biomolecules with PEC method.

  1. Mg-Zn based composites reinforced with bioactive glass (45S5) fabricated via powder metallurgy

    Science.gov (United States)

    Ab llah, N.; Jamaludin, S. B.; Daud, Z. C.; Zaludin, M. A. F.

    2016-07-01

    Metallic implants are shifting from bio-inert to bioactive and biodegradable materials. These changes are made in order to improve the stress shielding effect and bio-compatibility and also avoid the second surgery procedure. Second surgery procedure is required if the patient experienced infection and implant loosening. An implant is predicted to be well for 15 to 20 years inside patient body. Currently, magnesium alloys are found to be the new biomaterials because of their properties close to the human bones and also able to degrade in the human body. In this work, magnesium-zinc based composites reinforced with different content (5, 15, 20 wt. %) of bioactive glass (45S5) were fabricated through powder metallurgy technique. The composites were sintered at 450˚C. Density and porosity of the composites were determined using the gas pycnometer. Microstructure of the composites was observed using an optical microscope. In-vitro bioactivity behavior was evaluated in the simulated body fluid (SBF) for 7 days. Fourier Transform Infrared (FTIR) was used to characterize the apatite forming on the samples surface. The microstructure of the composite showed that the pore segregated near the grain boundaries and bioglass clustering was observed with increasing content of bioglass. The true density of the composites increased with the increasing content of bioglass and the highest value of porosity was indicated by the Mg-Zn reinforced with 20 wt.% of bioglass. The addition of bio-glass to the Mg-Zn has also induced the formation of apatite layer after soaking in SBF solution.

  2. Synthesis of ferrofluid based nanoarchitectured polypyrrole composites and its application for electromagnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Varshney, Swati [Polymeric and Soft Materials Section, National Physical Laboratory (CSIR), New Delhi 110012 (India); Department of Chemistry, Delhi Institute of Tool Engineering, Okhla, New Delhi 110020 (India); Amity Institute of Advanced Research and Studies, Materials and Devices, AIARS (M and D), Amity University, Noida, UP 201303 (India); Ohlan, Anil [Department of Physics, M.D. University, Rohtak, Haryana 124001 (India); Jain, V.K. [Amity Institute of Advanced Research and Studies, Materials and Devices, AIARS (M and D), Amity University, Noida, UP 201303 (India); Dutta, V.P. [Department of Chemistry, Delhi Institute of Tool Engineering, Okhla, New Delhi 110020 (India); Dhawan, S.K., E-mail: skdhawan@mail.nplindia.ernet.in [Polymeric and Soft Materials Section, National Physical Laboratory (CSIR), New Delhi 110012 (India)

    2014-01-15

    The monodispersion of magnetic nanoparticles in conducting polymer is the prerequisite to make a high quality composite for tunable electromagnetic interference (EMI) shielding. To meet this challenge, we have designed and synthesized ferrofluid based nanoarchitectured polypyrrole composites containing Fe{sub 3}O{sub 4} (8–12 nm) via in situ oxidative polymerization. To tune the microwave signals, polypyrrole composites (PFF) with different monomer/ferrofluid weight ratios have been prepared and characterized in microwave frequency domain. A maximum shielding effectiveness value of SE{sub A(max)} = 20.4 dB (∼99% attenuation) due to the absorption of microwave has been observed in the frequency range of 12.4–18 GHz and attenuation level varied with ferrofluid loading. The electrical conductivity of PFF composite is of the order of 10{sup −2} S cm{sup −1} order and having superparamagnetic nature with saturation magnetization (M{sub s}) of 5.5 emu g{sup −1}. The lightweight PFF composites with high attenuations can provide full control over the atomic structure and are favorable for the practical EMI shielding application for commercial electronic appliances. - Highlights: • Aqueous ferrofluid has been incorporated in polypyrrole matrix leads to PFF nanocomposites. • PFF composites shows conductivity of the order of 10{sup −2} S cm{sup −1} and saturation magnetization of 5.5 emu g{sup −1}. • Shielding effectiveness of 23.5 dB (SE{sub A} ∼ 20.4 dB and SE{sub R} ∼ 3.1 dB) has been achieved. • Shielding effectiveness depends on the ferrofluid loading.

  3. Conducting polymer and its composite materials based electrochemical sensor for Nicotinamide Adenine Dinucleotide (NADH).

    Science.gov (United States)

    Omar, Fatin Saiha; Duraisamy, Navaneethan; Ramesh, K; Ramesh, S

    2016-05-15

    Nicotinamide Adenine Dinucleotide (NADH) is an important coenzyme in the human body that participates in many metabolic reactions. The impact of abnormal concentrations of NADH significantly causes different diseases in human body. Electrochemical detection of NADH using bare electrode is a challenging task especially in the presence of main electroactive interferences such as ascorbic acid (AA), uric acid (UA) and dopamine (DA). Modified electrodes have been widely explored to overcome the problems of poor sensitivity and selectivity occurred from bare electrodes. This review gives an overview on the progress of using conducting polymers, polyelectrolyte and its composites (co-polymer, carbonaceous, metal, metal oxide and clay) based modified electrodes for the sensing of NADH. In addition, developments on the fabrication of numerous conducting polymer composites based modified electrodes are clearly described. PMID:26774092

  4. A Multi-dimension Qos based Local Service Selection Model for Service Composition

    Directory of Open Access Journals (Sweden)

    Liurong Hong

    2009-07-01

    Full Text Available There are two service selection strategies in dynamic service composition, i.e., global strategy and local strategy. The existed global service selection algorithms, due to insufficiently show users’ partiality and feature of the service, is unfavorable to encourage the service provider to optimize the service quality to some extent. In this paper, an ordinary utility function is used as a numerical scale of ordering local services, and then a multi-dimension Qos based local service selection model is proposed to provide important grounds to choose superior service and sift inferior service. Secondly, subjective weight mode, objective weight mode, and subject-objective weight mode are constructed to not only determine the weight coefficient of each Qos criterion, but also show users’ partiality and the objectivity of service quality. At last, this model is proved to be flexibility and effective based on our SEWSCP (Semantic Enable Web Service Composition Platform.

  5. Development of Design Procedures for Flexural Applications of Textile Composite Systems Based on Tension Stiffening Models

    OpenAIRE

    Mobasher, Barzin

    2011-01-01

    The Aveston Copper and Kelly (ACK) Method has been routinely used in estimating the efficiency of the bond between the textile and cementitious matrix. This method however has a limited applicability due to the simplifying assumptions such as perfect bond. A numerical model for simulation of tensile behavior of reinforced cement-based composites is presented to capture the inefficiency of the bond mechanisms. In this approach the role of interface properties which are instrumental in the simu...

  6. Multi-scale mechanism based life prediction of polymer matrix composites for high temperature airframe applications

    Science.gov (United States)

    Upadhyaya, Priyank

    A multi-scale mechanism-based life prediction model is developed for high-temperature polymer matrix composites (HTPMC) for high temperature airframe applications. In the first part of this dissertation the effect of Cloisite 20A (C20A) nano-clay compounding on the thermo-oxidative weight loss and the residual stresses due to thermal oxidation for a thermoset polymer bismaleimide (BMI) are investigated. A three-dimensional (3-D) micro-mechanics based finite element analysis (FEA) was conducted to investigate the residual stresses due to thermal oxidation using an in-house FEA code (NOVA-3D). In the second part of this dissertation, a novel numerical-experimental methodology is outlined to determine cohesive stress and damage evolution parameters for pristine as well as isothermally aged (in air) polymer matrix composites. A rate-dependent viscoelastic cohesive layer model was implemented in an in-house FEA code to simulate the delamination initiation and propagation in unidirectional polymer composites before and after aging. Double cantilever beam (DCB) experiments were conducted (at UT-Dallas) on both pristine and isothermally aged IM-7/BMI composite specimens to determine the model parameters. The J-Integral based approach was adapted to extract cohesive stresses near the crack tip. Once the damage parameters had been characterized, the test-bed FEA code employed a micromechanics based viscoelastic cohesive layer model to numerically simulate the DCB experiment. FEA simulation accurately captures the macro-scale behavior (load-displacement history) simultaneously with the micro-scale behavior (crack-growth history).

  7. Mass spectrometric base composition profiling: Implications for forensic mtDNA databasing

    OpenAIRE

    Eduardoff, Mayra; Huber, Gabriela; Bayer, Birgit; Schmid, Dagmar; Anslinger, Katja; Göbel, Tanja; Zimmermann, Bettina; Schneider, Peter M; Röck, Alexander W; Parson, Walther

    2013-01-01

    In forensic genetics mitochondrial DNA (mtDNA) is usually analyzed by direct Sanger-type sequencing (STS). This method is known to be laborious and sometimes prone to human error. Alternative methods have been proposed that lead to faster results. Among these are methods that involve mass-spectrometry resulting in base composition profiles that are, by definition, less informative than the full nucleotide sequence. Here, we applied a highly automated electrospray ionization mass spectrometry ...

  8. Bio-based thermoset composites from epoxidised linseed oil and expanded starch

    OpenAIRE

    Supanchaiyamat, Nontipa; Hunt, Andrew J.; Peter S. Shuttleworth; DING, CHENG; James H. Clark; Matharu, Avtar S.

    2014-01-01

    Bio-based thermoset composites comprising epoxidised linseed oil (ELO), a bio-derived diacid crosslinker (Pripol 1009) and starch are reported. High amylose corn starch in its native, gelatinised and retrograded forms were used in the formulation to yield water resistant films with good thermal stability. The textural properties of gelatinised and retrograded starches were characterised using scanning electron microscopy and porosimetry and their thermal stability was determined using thermog...

  9. Changes in base composition bias of nuclear and mitochondrial genes in lice (Insecta: Psocodea).

    OpenAIRE

    Yoshizawa, Kazunori; Johnson, Kevin P.

    2013-01-01

    While it is well known that changes in the general processes of molecular evolution have occurred on a variety of timescales, the mechanisms underlying these changes are less well understood. Parasitic lice ("Phthiraptera") and their close relatives (infraorder Nanopsocetae of the insect order Psocodea) are a group of insects well known for their unusual features of molecular evolution. We examined changes in base composition across parasitic lice and bark lice. We identified substantial diff...

  10. Changes in base composition bias of nuclear and mitochondrial genes in lice (Insecta: Psocodea).

    Science.gov (United States)

    Yoshizawa, Kazunori; Johnson, Kevin P

    2013-12-01

    While it is well known that changes in the general processes of molecular evolution have occurred on a variety of timescales, the mechanisms underlying these changes are less well understood. Parasitic lice ("Phthiraptera") and their close relatives (infraorder Nanopsocetae of the insect order Psocodea) are a group of insects well known for their unusual features of molecular evolution. We examined changes in base composition across parasitic lice and bark lice. We identified substantial differences in percent GC content between the clade comprising parasitic lice plus closely related bark lice (=Nanopsocetae) versus all other bark lice. These changes occurred for both nuclear and mitochondrial protein coding and ribosomal RNA genes, often in the same direction. To evaluate whether correlations in base composition change also occurred within lineages, we used phylogenetically controlled comparisons, and in this case few significant correlations were identified. Examining more constrained sites (first/second codon positions and rRNA) revealed that, in comparison to the other bark lice, the GC content of parasitic lice and close relatives tended towards 50 % either up from less than 50 % GC or down from greater than 50 % GC. In contrast, less constrained sites (third codon positions) in both nuclear and mitochondrial genes showed less of a consistent change of base composition in parasitic lice and very close relatives. We conclude that relaxed selection on this group of insects is a potential explanation of the change in base composition for both mitochondrial and nuclear genes, which could lead to nucleotide frequencies closer to random expectation (i.e., 50 % GC) in the absence of any mutation bias. Evidence suggests this relaxed selection arose once in the non-parasitic common ancestor of Phthiraptera + Nanopsocetae and is not directly related to the evolution of the parasitism in lice. PMID:24233690

  11. Evaluation of Ferrocene Derivatives as Burn Rate Modifiers in AP/HTPB-Based Composite Propellants

    OpenAIRE

    G. M. Gore; K. R. Tipare; R. G. Bhatewara; U.S. Prasad; Manoj Gupta; S. K. Mane

    1999-01-01

    Some ferrocene derivatives like 2,4-dinitrophenylhydrazine derivative of acetyl ferrocene, 1-pyrrolidinylmethyl ferrocene, di-ter-butyl ferrocene and 1,3-diferrocenyl-l-butene (DFB) have been synthesised and characterised by infrared, nuclear magnetic resonance, ultraviolet, iron content, etc. To study the effect of their incorporation on performance, ammonium perchlorate/hydroxyl-terminated polybutadiene-based composite propellants containing these derivatives have been prepared and studied ...

  12. Application of Laser Based Ultrasound for NDE of Damage in Thick Stitched Composites

    Science.gov (United States)

    Anastasi, Robert F.; Friedman, Adam D.; Hinders, Mark K.; Madaras, Eric I.

    1997-01-01

    As design engineers implement new composite systems such as thick, load bearing composite structures, they must have certifiable confidence in structure s durability and worthiness. This confidence builds from understanding the structural response and failure characteristics of simple components loaded in testing machines to tests on full scale sections. Nondestructive evaluation is an important element which can provide quantitative information on the damage initiation, propagation, and final failure modes for the composite structural components. Although ultrasound is generally accepted as a test method, the use of conventional ultrasound for in-situ monitoring of damage during tests of large structures is not practical. The use of lasers to both generate and detect ultrasound extends the application of ultrasound to in- situ sensing of damage in a deformed structure remotely and in a non-contact manner. The goal of the present research is to utilize this technology to monitor damage progression during testing. The present paper describes the application of laser based ultrasound to quantify damage in thick stitched composite structural elements to demonstrate the method. This method involves using a Q-switched laser to generate a rapid, local linear thermal strain on the surface of the structure. This local strain causes the generation of ultrasonic waves into the material. A second laser used with a Fabry-Perot interferometer detects the surface deflections. The use of fiber optics provides for eye safety and a convenient method of delivering the laser over long distances to the specimens. The material for these structural elements is composed of several stacks of composite material assembled together by stitching through the laminate thickness that ranging from 0.5 to 0.8 inches. The specimens used for these nondestructive evaluation studies had either impact damage or skin/stiffener interlaminar failure. Although little or no visible surface damage existed

  13. Estimation of Elasticity of Porous Rock Based on Mineral Composition and Microstructure

    Directory of Open Access Journals (Sweden)

    Zaobao Liu

    2013-01-01

    Full Text Available Estimation of elastic parameters of porous rock like the compressibility of sandstone is scientifically important and yet an open issue. This study illustrates the estimation of the elastic compressibility of sandstone (ECS based on the assumption that the ECS is determined closely by the mineral composition and microstructures. In this study, 37 samples are collected to evaluate the estimations of the ECS obtained by different methods. The regression analysis is first implemented using the 37 samples. The results show that ECS exhibits linear relations with the rock minerals, pores, and applied compressive stress. Then the support vector machine (SVM optimized by the particle swarm optimization algorithm (PSO is examined to generate estimations of the ECS based on the mineral composition and microstructures. The SVM is trained with 30 samples to search for optimal parameters using the PSO, and thus the estimation model is established. Afterwards, this model is validated to give predictions of the left 7 samples. By comparison with the regression methods, the proposed strategy, that is, the PSO optimized SVM, performs much better on the training samples and shows a good capability in generating estimations of the ECS of the 7 testing samples based on the mineral composition and microstructures.

  14. Heterocyclic aramid nanoparticle-assisted graphene exfoliation for fabrication of pristine graphene-based composite paper

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Yao; Liu, Qi; Fan, Jinchen, E-mail: Jinchen.fan@shiep.edu.cn; Shi, Penghui; Min, Yulin, E-mail: ahaqmylin@126.com; Xu, Qunjie [Shanghai University of Electric Power, Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, College of Environmental and Chemical Engineering (China)

    2015-07-15

    Mechanically strong, electrically conductive, and flexible pristine graphene-based composite paper was prepared based on heterocyclic aramid nanoparticle-assisted liquid-phase exfoliation of graphite. The macroscopic heterocyclic aramid yarns were split and assembled into heterocyclic aramid nanoparticles with the size of ∼30 nm by deprotonation in dimethylsulfoxide in the presence of potassium hydroxide. The obtained heterocyclic aramid nanoparticles dimethylsulfoxide dispersion was used as good medium solvent for highly efficiency liquid-phase exfoliation of graphite. The results demonstrated that the concentration of exfoliated graphene can facile reaches ∼2.72 mg/mL after direct sonication of 7 h with assist of heterocyclic aramid nanoparticles. After exfoliation, the self-assembled pristine graphene-based composite paper was fabricated by vacuum-assisted filtration. Due to the introduction of heterocyclic aramid nanoparticles, the self-assembled pristine graphene/heterocyclic aramid nanoparticles composite paper exhibited good mechanical property with tensile strength of ∼129.7 MPa, meantime, has a high electrical conductivity of ∼1.42 × 10{sup 4} S/m.

  15. Heterocyclic aramid nanoparticle-assisted graphene exfoliation for fabrication of pristine graphene-based composite paper

    International Nuclear Information System (INIS)

    Mechanically strong, electrically conductive, and flexible pristine graphene-based composite paper was prepared based on heterocyclic aramid nanoparticle-assisted liquid-phase exfoliation of graphite. The macroscopic heterocyclic aramid yarns were split and assembled into heterocyclic aramid nanoparticles with the size of ∼30 nm by deprotonation in dimethylsulfoxide in the presence of potassium hydroxide. The obtained heterocyclic aramid nanoparticles dimethylsulfoxide dispersion was used as good medium solvent for highly efficiency liquid-phase exfoliation of graphite. The results demonstrated that the concentration of exfoliated graphene can facile reaches ∼2.72 mg/mL after direct sonication of 7 h with assist of heterocyclic aramid nanoparticles. After exfoliation, the self-assembled pristine graphene-based composite paper was fabricated by vacuum-assisted filtration. Due to the introduction of heterocyclic aramid nanoparticles, the self-assembled pristine graphene/heterocyclic aramid nanoparticles composite paper exhibited good mechanical property with tensile strength of ∼129.7 MPa, meantime, has a high electrical conductivity of ∼1.42 × 104 S/m.

  16. Electrodeposition of Gold on Lignocelluloses and Graphite-Based Composite Paper Electrodes for Superior Electrical Properties

    Science.gov (United States)

    Sultana, Ishrat; Razaq, Aamir; Idrees, M.; Asif, M. H.; Ali, Hassan; Arshad, Asim; Iqbal, Shahid; Ramay, Shahid M.; Hussain, Shahzada Qamar

    2016-10-01

    Graphite-based composites are commonly used as an anode and current collector for energy storage devices; however, they have inherently limited potential for large scale rechargeable systems due to a brittle structure. In this study, flexible and light-weight graphite-based electrodes are prepared by incorporation of lignocelluloses fibers directly collected from a self-growing plant, Typha Angistifolia. Electrical properties of graphite and lignocelluloses composite sheets are enhanced by electrodeposition of gold in a three-electrode setup. Electrochemical deposition of gold on a lignocelluloses/graphite paper electrode was obtained in potentiostatic mode by the application of reduction potential -0.95 V for 2000 s, 600 s, and 100 s. The gold-deposited paper electrodes showed efficient kinetics by shifting redox peaks towards lower potentials in cyclic voltammetry measurements, whereas impedance measurements revealed seven orders of magnitude reduction in the resistive properties. Incorporated flexibility and superior electrical/electrochemical performance within presented graphite-based composites will provide cutting-edge characteristics for high-tech application of energy storage devices by keeping a focus on modern disposable technology.

  17. Carbon fiber based composites stress analysis. Experimental and computer comparative studies

    Science.gov (United States)

    Sobek, M.; Baier, A.; Buchacz, A.; Grabowski, Ł.; Majzner, M.

    2015-11-01

    Composite materials used nowadays for the production of composites are the result of advanced research. This allows assuming that they are among the most elaborate tech products of our century. That fact is evidenced by the widespread use of them in the most demanding industries like aerospace and space industry. But the heterogeneous materials and their advantages have been known to mankind in ancient times and they have been used by nature for millions of years. Among the fibers used in the industry most commonly used are nylon, polyester, polypropylene, boron, metal, glass, carbon and aramid. Thanks to their physical properties last three fiber types deserve special attention. High strength to weight ratio allow the use of many industrial solutions. Composites based on carbon and glass fibers are widely used in the automotive. Aramid fibers ideal for the fashion industry where the fabric made from the fibers used to produce the protective clothing. In the paper presented issues of stress analysis of composite materials have been presented. The components of composite materials and principles of composition have been discussed. Particular attention was paid to the epoxy resins and the fabrics made from carbon fibers. The article also includes basic information about strain measurements performed on with a resistance strain gauge method. For the purpose of the laboratory tests a series of carbon - epoxy composite samples were made. For this purpose plain carbon textile was used with a weight of 200 g/mm2 and epoxy resin LG730. During laboratory strain tests described in the paper Tenmex's delta type strain gauge rosettes were used. They were arranged in specific locations on the surface of the samples. Data acquisition preceded using HBM measurement equipment, which included measuring amplifier and measuring head. Data acquisition was performed using the Easy Catman. In order to verify the results of laboratory tests numerical studies were carried out in a

  18. Application of Al2O3-based polyimide composite thick films to integrated substrates using aerosol deposition method

    International Nuclear Information System (INIS)

    Al2O3-based polyimide composite thick films were successfully fabricated with reduction of residual stress and improvement in plasticity for integrated substrates at room temperature by aerosol deposition method. Scanning electron microscopy and energy dispersive spectroscopy mappings exhibited a high content of Al2O3 evenly distributed in the composite thick films. The relative dielectric permittivity and loss tangent of Al2O3-based polyimide composite thick films were 7.6 and 0.007, respectively. There was almost no change in the crystallite size of Al2O3-based polyimide composite thick films compared with that of starting powder due to the reduction of kinetic energy by polyimide during collision on the substrates. Moreover, it was confirmed that the residual stress of Al2O3-based polyimide composite thick films remarkably decreased compared with that of Al2O3 thick films.

  19. The effect of load cycling on microleakage of low shrinkage methacrylate base composite compared with silorane base composite and SEM evaluation of marginal integrity

    Directory of Open Access Journals (Sweden)

    Hamid Kermanshah

    2013-04-01

    Full Text Available Background and Aims: Marginal seal in class V cavity and determination of the best restorative material in reducing microleakage is of great concern in operative dentistry. The aim of this study was to evaluate the effect of load cycling on the microleakage of low shrinkage composites compared with methacrylate-based composites with low shirinkage rate in class V cavity preparation. Marginal integrity of these materials was assessed using scanning electron microscope (SEM. Materials and Methods: In this in vitro study, class V cavity preparations were made on the buccal and lingual surfaces of 48 human premolars and molars (96 cavities. The specimens were divided into four groups each containing 12 teeth (24 cavities: group 1 (Kalore-GC+ G-Bond , group 2 (Futurabond NR+Grandio, group 3(All Bond SE+ Aelite LS Posterior, group 4 (LS System Adhesive Primer & Bond+Filtek P90. All the specimens were thermocycled for 2000 cycles (5-50oC. In each group, half of the specimens (n=12 were subjected to 200,000 cycles of loading at 80 N. Epoxy resin replicas of 32 specimens (4 restorations in each subgroup were evaluated using SEM and the interfacial gaps were measured. Finally, the teeth were immersed in 0.5% basic fuchsin dye for 24 hours at 370C, then sectioned and observed under stereomicroscope. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests and the comparison between occlusal and gingival microleakage was made with Wilcoxon test. Results: Within unloaded or loaded specimens, there were no significant differences in microleakage among four groups on the occlusal margins (P>0.05. But there were statistically significant differences in microleakage between silorane and Aelite on the gingival margins (P0.05. Conclusion: Silorane did not perform better than the conventional low shrinkage methacrylate-based composite in terms of sealing ability (except Aelite. Cyclic loading did not increase the extent of leakage in any groups.

  20. Processing of high performance composites based on peek by aqueous suspension prepregging

    Directory of Open Access Journals (Sweden)

    Liliana Burakowski Nohara

    2010-06-01

    Full Text Available The use of polyamic acid (PAA precursor as interphase in polymer composites is one of the many applications of polyimides (PIs. In this work, composites based on poly(ether-ether-ketone (PEEK and carbon fibers were prepared using two manufacturing techniques for thermoplastic composites: hot compression molding, and aqueous polymeric suspension prepregging using PIs as interphase. Two PAAs were synthesized and used as interphases: 3,3'-4,4'-benzophenonetetracarboxylic dianhydride/oxydianiline (BTDA/ODA and pyromellitic dianhydride/oxydianiline (PMDA/ODA. The PAA/PI systems were analyzed by differential scanning calorimetry (DSC, thermogravimetry (TGA, Fourier transform infrared spectroscopy (FTIR and nuclear magnetic resonance (NMR. Results from these analyses confirmed the synthesis of these compounds. Aqueous polymeric suspension prepregging was more efficient than hot compression molding when the PMDA/ODA PAA/PI interphase was used; also, the interlaminar shear strength of composites produced using this technique was 14.5% higher than the one produced using hot compression molding.

  1. Evaluation of modal-based damage detection techniques for composite aircraft sandwich structures

    Science.gov (United States)

    Oliver, J. A.; Kosmatka, J. B.

    2005-05-01

    Composite sandwich structures are important as structural components in modern lightweight aircraft, but are susceptible to catastrophic failure without obvious forewarning. Internal damage, such as disbonding between skin and core, is detrimental to the structures' strength and integrity and thus must be detected before reaching critical levels. However, highly directional low density cores, such as Nomex honeycomb, make the task of damage detection and health monitoring difficult. One possible method for detecting damage in composite sandwich structures, which seems to have received very little research attention, is analysis of global modal parameters. This study will investigate the viability of modal analysis techniques for detecting skin-core disbonds in carbon fiber-Nomex honeycomb sandwich panels through laboratory testing. A series of carbon fiber prepreg and Nomex honeycomb sandwich panels-representative of structural components used in lightweight composite airframes-were fabricated by means of autoclave co-cure. All panels were of equal dimensions and two were made with predetermined sizes of disbonded areas, created by substituting areas of Teflon release film in place of epoxy film adhesive during the cure. A laser vibrometer was used to capture frequency response functions (FRF) of all panels, and then real and imaginary FRFs at different locations on each plate and operating shapes for each plate were compared. Preliminary results suggest that vibration-based techniques hold promise for damage detection of composite sandwich structures.

  2. QoS measurement of workflow-based web service compositions using Colored Petri net.

    Science.gov (United States)

    Nematzadeh, Hossein; Motameni, Homayun; Mohamad, Radziah; Nematzadeh, Zahra

    2014-01-01

    Workflow-based web service compositions (WB-WSCs) is one of the main composition categories in service oriented architecture (SOA). Eflow, polymorphic process model (PPM), and business process execution language (BPEL) are the main techniques of the category of WB-WSCs. Due to maturity of web services, measuring the quality of composite web services being developed by different techniques becomes one of the most important challenges in today's web environments. Business should try to provide good quality regarding the customers' requirements to a composed web service. Thus, quality of service (QoS) which refers to nonfunctional parameters is important to be measured since the quality degree of a certain web service composition could be achieved. This paper tried to find a deterministic analytical method for dependability and performance measurement using Colored Petri net (CPN) with explicit routing constructs and application of theory of probability. A computer tool called WSET was also developed for modeling and supporting QoS measurement through simulation. PMID:25110748

  3. QoS Measurement of Workflow-Based Web Service Compositions Using Colored Petri Net

    Directory of Open Access Journals (Sweden)

    Hossein Nematzadeh

    2014-01-01

    Full Text Available Workflow-based web service compositions (WB-WSCs is one of the main composition categories in service oriented architecture (SOA. Eflow, polymorphic process model (PPM, and business process execution language (BPEL are the main techniques of the category of WB-WSCs. Due to maturity of web services, measuring the quality of composite web services being developed by different techniques becomes one of the most important challenges in today’s web environments. Business should try to provide good quality regarding the customers’ requirements to a composed web service. Thus, quality of service (QoS which refers to nonfunctional parameters is important to be measured since the quality degree of a certain web service composition could be achieved. This paper tried to find a deterministic analytical method for dependability and performance measurement using Colored Petri net (CPN with explicit routing constructs and application of theory of probability. A computer tool called WSET was also developed for modeling and supporting QoS measurement through simulation.

  4. Toughening and healing of continuous fibre reinforced composites with bis-maleimide based pre-pregs

    Science.gov (United States)

    Kostopoulos, V.; Kotrotsos, A.; Tsantzalis, S.; Tsokanas, P.; Christopoulos, A. C.; Loutas, T.

    2016-08-01

    Unidirectional (UD) pre-pregs containing self-healing materials based on Diels-Alder reaction bis-maleimide (BMI) polymers were successfully incorporated on the mid-plane of UD carbon fibre reinforced polymers. The fracture toughness of these composites and the introduced healing capability were measured under mode I loading. The interlaminar fracture toughness was enhanced considerably, since the maximum load (P max) of the modified composite increased approximately 1.5 times and the mode I fracture energy (G IC) displayed a significant increase of almost 3.5 times when compared to the reference composites. Furthermore the modified composites displayed a healing efficiency (HE) value of about 30% for P max and 20% for G IC after the first healing, appearing to be an almost stable behaviour after the third healing cycle. The HE displayed a decrease of 20% and 15% for P max and G IC values, respectively, after the fifth healing cycle. During the tests, the monitored acoustic emission (AE) activity of the samples showed that there is no significant difference due to the presence of BMI polymer in terms of AE hits. Moreover, optical microscopy not only showed that the epoxy matrix at the interface is partly infiltrated by the BMI polymer, but it also revealed the presence of pulled out fibres at the fractured surface, indicating ductile behaviour.

  5. QoS Measurement of Workflow-Based Web Service Compositions Using Colored Petri Net

    Science.gov (United States)

    Nematzadeh, Hossein; Motameni, Homayun; Nematzadeh, Zahra

    2014-01-01

    Workflow-based web service compositions (WB-WSCs) is one of the main composition categories in service oriented architecture (SOA). Eflow, polymorphic process model (PPM), and business process execution language (BPEL) are the main techniques of the category of WB-WSCs. Due to maturity of web services, measuring the quality of composite web services being developed by different techniques becomes one of the most important challenges in today's web environments. Business should try to provide good quality regarding the customers' requirements to a composed web service. Thus, quality of service (QoS) which refers to nonfunctional parameters is important to be measured since the quality degree of a certain web service composition could be achieved. This paper tried to find a deterministic analytical method for dependability and performance measurement using Colored Petri net (CPN) with explicit routing constructs and application of theory of probability. A computer tool called WSET was also developed for modeling and supporting QoS measurement through simulation. PMID:25110748

  6. Scratch-resistant, highly conductive, and high-strength carbon nanotube-based composite yarns.

    Science.gov (United States)

    Liu, Kai; Sun, Yinghui; Lin, Xiaoyang; Zhou, Ruifeng; Wang, Jiaping; Fan, Shoushan; Jiang, Kaili

    2010-10-26

    High-strength and conductive carbon nanotube (CNT) yarns are very attractive in many potential applications. However, there is a difficulty when simultaneously enhancing the strength and conductivity of CNT yarns. Adding some polymers into CNT yarns to enhance their strength will decrease their conductivity, while treating them in acid or coating them with metal nanoparticles to enhance their conductivity will reduce their strength. To overcome this difficulty, here we report a method to make high-strength and highly conductive CNT-based composite yarns by using a continuous superaligned CNT (SACNT) yarn as a conductive framework and then inserting polyvinyl alcohol (PVA) into the intertube spaces of the framework through PVA/dimethyl sulphoxide solution to enhance the strength of yarns. The as-produced CNT/PVA composite yarns possess very high tensile strengths up to 2.0 GPa and Young's moduli more than 120 GPa, much higher than those of the CNT/PVA yarns reported. The electric conductivity of as-produced composite yarns is as high as 9.2 × 10(4) S/m, comparable to HNO(3)-treated or Au nanoparticle-coated CNT yarns. These composite yarns are flexible, lightweight, scratch-resistant, very stable in the lab environment, and resistant to extremely humid ambient and as a result can be woven into high-strength and heatable fabrics, showing potential applications in flexible heaters, bullet-proof vests, radiation protection suits, and spacesuits.

  7. Power generation from base excitation of a Kevlar composite beam with ZnO nanowires

    Science.gov (United States)

    Malakooti, Mohammad H.; Hwang, Hyun-Sik; Sodano, Henry A.

    2015-04-01

    One-dimensional nanostructures such as nanowires, nanorods, and nanotubes with piezoelectric properties have gained interest in the fabrication of small scale power harvesting systems. However, the practical applications of the nanoscale materials in structures with true mechanical strengths have not yet been demonstrated. In this paper, piezoelectric ZnO nanowires are integrated into the fiber reinforced polymer composites serving as an active phase to convert the induced strain energy from ambient vibration into electrical energy. Arrays of ZnO nanowires are grown vertically aligned on aramid fibers through a low-cost hydrothermal process. The modified fabrics with ZnO nanowires whiskers are then placed between two carbon fabrics as the top and the bottom electrodes. Finally, vacuum resin transfer molding technique is utilized to fabricate these multiscale composites. The fabricated composites are subjected to a base excitation using a shaker to generate charge due to the direct piezoelectric effect of ZnO nanowires. Measuring the generated potential difference between the two electrodes showed the energy harvesting application of these multiscale composites in addition to their superior mechanical properties. These results propose a new generation of power harvesting systems with enhanced mechanical properties.

  8. HOMOGENIZATION—BASED TOPOLOGY DESIGN FOR PURE TORSION OF COMPOSITE SHAFTS

    Institute of Scientific and Technical Information of China (English)

    袁振; 吴长春; 李华

    2003-01-01

    In conjunction with the homogenization theory and the finite element method, themathematical models for designing the cross-section of composite shafts by maximizing the torsionrigidity axe developed in this paper. To obtain the extremal torsion rigidity, both the cross-section ofthe macro scale shaft and the representative microstructure of the composite material are optimizedusing the new models. The micro scale computational model addresses the problem of finding theperiodic microstructures with extreme shear moduli. The optimal microstructure obtained with thenew model and the homogenization method can be used to improve and optimize natural or artificialmaterials. In order to be more practical for engineering applications, cellular materials rather thanranked materials are used in the optimal process in the existence of optimal bounds for the elasticproperties. Moreover, the macro scale model is proposed to optimize the cross-section of the torsionalshaft based on the tailared composites. The validating optimal results show that the models are veryeffective in obtaining composites with extreme elastic properties, and the cross-section of the compositeshaft with the extremal torsion rigidity.

  9. Solar-driven photocatalytic treatment of diclofenac using immobilized TiO2-based zeolite composites.

    Science.gov (United States)

    Kovacic, Marin; Salaeh, Subhan; Kusic, Hrvoje; Suligoj, Andraz; Kete, Marko; Fanetti, Mattia; Stangar, Urska Lavrencic; Dionysiou, Dionysios D; Bozic, Ana Loncaric

    2016-09-01

    The study is aimed at evaluating the potential of immobilized TiO2-based zeolite composite for solar-driven photocatalytic water treatment. In that purpose, TiO2-iron-exchanged zeolite (FeZ) composite was prepared using commercial Aeroxide TiO2 P25 and iron-exchanged zeolite of ZSM5 type, FeZ. The activity of TiO2-FeZ, immobilized on glass support, was evaluated under solar irradiation for removal of diclofenac (DCF) in water. TiO2-FeZ immobilized in a form of thin film was characterized for its morphology, structure, and composition using scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). Diffuse reflectance spectroscopy (DRS) was used to determine potential changes in band gaps of prepared TiO2-FeZ in comparison to pure TiO2. The influence of pH, concentration of hydrogen peroxide, FeZ wt% within the composite, and photocatalyst dosage on DCF removal and conversion efficiency by solar/TiO2-FeZ/H2O2 process was investigated. TiO2-FeZ demonstrated higher photocatalytic activity than pure TiO2 under solar irradiation in acidic conditions and presence of H2O2. PMID:27255319

  10. Solar-driven photocatalytic treatment of diclofenac using immobilized TiO2-based zeolite composites.

    Science.gov (United States)

    Kovacic, Marin; Salaeh, Subhan; Kusic, Hrvoje; Suligoj, Andraz; Kete, Marko; Fanetti, Mattia; Stangar, Urska Lavrencic; Dionysiou, Dionysios D; Bozic, Ana Loncaric

    2016-09-01

    The study is aimed at evaluating the potential of immobilized TiO2-based zeolite composite for solar-driven photocatalytic water treatment. In that purpose, TiO2-iron-exchanged zeolite (FeZ) composite was prepared using commercial Aeroxide TiO2 P25 and iron-exchanged zeolite of ZSM5 type, FeZ. The activity of TiO2-FeZ, immobilized on glass support, was evaluated under solar irradiation for removal of diclofenac (DCF) in water. TiO2-FeZ immobilized in a form of thin film was characterized for its morphology, structure, and composition using scanning electron microscopy/energy-dispersive x-ray spectroscopy (SEM/EDX). Diffuse reflectance spectroscopy (DRS) was used to determine potential changes in band gaps of prepared TiO2-FeZ in comparison to pure TiO2. The influence of pH, concentration of hydrogen peroxide, FeZ wt% within the composite, and photocatalyst dosage on DCF removal and conversion efficiency by solar/TiO2-FeZ/H2O2 process was investigated. TiO2-FeZ demonstrated higher photocatalytic activity than pure TiO2 under solar irradiation in acidic conditions and presence of H2O2.

  11. Caracterisation des proprietes dielectriques de materiaux composites a base de polyethylene terephtalate recycle

    Science.gov (United States)

    Mebarki, Fouzia

    The aim of this study is to examine the possibility of using thermoplastic composite materials for electrical applications such as supports of automotive engine ignition systems. We are particularly interested in composites based on recycled polyethylene terephtalate (PET). Conventional isolations like PET cannot meet the new prescriptive requirements. The introduction of reinforcement materials, such as glass fibers and mica can improve the mechanical characteristics of these materials. However, this enhancement may also reduce electrical properties especially since these composites have to be used under severe thermal and electric stresses. In order to estimate PET composite insulation lifetimes, accelerated aging tests were carried out at temperatures ranging from room temperature to 140°C and at a frequency of 300Hz. Studies at high temperature will help to identify the service temperature of candidate materials. Dielectric breakdown tests have been made on a large number of samples according to the standard of dielectric strength tests of solid insulating ASTM D-149. These tests have to identify the problematic samples and to check solid insulation quality. The different knowledge gained from this analysis was used to predict material performance. This will give the company the possibility to improve existing formulations and subsequently develop a material having electrical and thermal properties suitable for this application.

  12. Schottky Diodes Based on Polyaniline/Multi-Walled Carbon Nanotube Composites

    Science.gov (United States)

    Hajibadali, A.; Nejad, M. Baghaei; Farzi, G.

    2015-08-01

    Polyaniline/multi-walled carbon nanotube composites (PANI/MWCNT), with various concentration of multi-walled carbon nanotube, were synthesized. Several Schottky diodes were fabricated, where PANI or PANI/MWCNT composites, aluminum, and gold were used as semiconductor, Schottky contact, and ohmic contact, respectively. Then current-voltage characteristics of the fabricated diodes were measured at room temperature and within the bias range of -5 to +5 V. The measurements were repeated three times for each sample to verify repeatability of experiment. The obtained results show that by increasing the MWCNT concentration, the current intensity increases. Furthermore, I-V characteristics of pure polyaniline Schottky diode follows the thermionic emission mechanism while the I-V characteristics of Schottky diodes based on PANI/MWCNT composites show two distinct power law regions. At lower voltages, the mechanism follows Ohm's Law, whereas at higher voltages, the mechanism is compatible with space charge limited conduction emission mechanism. The parameters of Schottky diodes were determined, and it was observed that critical voltage decreased when the concentration of MWCNT in the composite increased.

  13. Toughening and healing of continuous fibre reinforced composites with bis-maleimide based pre-pregs

    Science.gov (United States)

    Kostopoulos, V.; Kotrotsos, A.; Tsantzalis, S.; Tsokanas, P.; Christopoulos, A. C.; Loutas, T.

    2016-08-01

    Unidirectional (UD) pre-pregs containing self-healing materials based on Diels–Alder reaction bis-maleimide (BMI) polymers were successfully incorporated on the mid-plane of UD carbon fibre reinforced polymers. The fracture toughness of these composites and the introduced healing capability were measured under mode I loading. The interlaminar fracture toughness was enhanced considerably, since the maximum load (P max) of the modified composite increased approximately 1.5 times and the mode I fracture energy (G IC) displayed a significant increase of almost 3.5 times when compared to the reference composites. Furthermore the modified composites displayed a healing efficiency (HE) value of about 30% for P max and 20% for G IC after the first healing, appearing to be an almost stable behaviour after the third healing cycle. The HE displayed a decrease of 20% and 15% for P max and G IC values, respectively, after the fifth healing cycle. During the tests, the monitored acoustic emission (AE) activity of the samples showed that there is no significant difference due to the presence of BMI polymer in terms of AE hits. Moreover, optical microscopy not only showed that the epoxy matrix at the interface is partly infiltrated by the BMI polymer, but it also revealed the presence of pulled out fibres at the fractured surface, indicating ductile behaviour.

  14. Stacking interaction in metal complexes with compositions of DNA and heteroaromatic N-bases

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The current development in the intramolecular aromatic-ring stacking i nteractions in the complexes with compositions of DNA and heteroaromatic N-bases has been reviewed to a great extent, especially the significant contributions i n several important systems about ternary mixed-ligand complexes, including nucl eotide-metal ion-po- lyaromatic amine, amino acid-metal ion-polyaromatic amine, nucleotide-metal ion-pyridine-like aromatic amine, nucleotide-metal ion-amino ac id, nucleotide-metal ion-nucleic acid base, nucleic acid base-metal ion, and the important factors affecting the intramolecular aromatic-ring stacking interacti ons in the complexes. Based on the study of stacking interaction in the complexe s, the mechanism of interaction between DNA molecules and complexes of heteroaro matic N-bases has been established, which is crucial for the design and synthesi s of the complexes acting as molecular devices of DNA.

  15. Characterising structural, mechanical and cytotoxic properties of coral-based composite material intended for bone implant applications

    Directory of Open Access Journals (Sweden)

    Angela Samper Gaitán

    2011-08-01

    Full Text Available Studies concerning the application of Porites asteroides coral for bone implant purposes have demonstrated the biological viability of its use. As a complement to previous research regarding the development of bone-powder based composite materials which are useful for such applications, this study was aimed at developing a coral powder-based composite material which would be able to satisfy the appropriate structural, mechanical and cytotoxic properties required for its use. A composite material made of coral powder, calcium sulphate powder and water was therefore developed, and its properties were tested in different compositions. The results showed how the resulting composite material had properties which were comparable to those of human cortical bone (from both a structural and mechanical point of view, as well as being non-toxic below a 0.35 mg/ml critical composite material concentration.

  16. Hygroscopicity-resistant mechanism of an α-starch based composite binder for dry sand molds and cores

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Hygroscopicity-resistance of an α-starch based composite binder for dry sand molds (cores) has been studied experimentally and theoretically. Focus is placed on the relationship between the hardening structure and humidity-resistance of the composite binder. The results show that the α-starch composite binder has good humidity-resistance due to its special complex structure. SEM observations illustrate that the composite binder consists of reticular matrix and a ball- or lump-shaped reinforcement phase, and the specific property of the binding membrane with heterogeneous structure is affected by humidity to a small extent. Based on the analyses on the interplays of different ingredients in the binder at hardening, the structure model and hygroscopicity-resistant mechanisms of the hardening composite binder were further proposed. Moreover, the reasons for good humidity-resistance of the composite binder bonded sand are well explained by the humidity-resistant mechanisms.

  17. A Novel Multiscale Physics Based Progressive Failure Methodology for Laminated Composite Structures

    Science.gov (United States)

    Pineda, Evan J.; Waas, Anthony M.; Bednarcyk, Brett A.; Collier, Craig S.; Yarrington, Phillip W.

    2008-01-01

    A variable fidelity, multiscale, physics based finite element procedure for predicting progressive damage and failure of laminated continuous fiber reinforced composites is introduced. At every integration point in a finite element model, progressive damage is accounted for at the lamina-level using thermodynamically based Schapery Theory. Separate failure criteria are applied at either the global-scale or the microscale in two different FEM models. A micromechanics model, the Generalized Method of Cells, is used to evaluate failure criteria at the micro-level. The stress-strain behavior and observed failure mechanisms are compared with experimental results for both models.

  18. Drag-based composite super-twisting sliding mode control law design for Mars entry guidance

    Science.gov (United States)

    Zhao, Zhenhua; Yang, Jun; Li, Shihua; Guo, Lei

    2016-06-01

    In this paper, the drag-based trajectory tracking guidance problem is investigated for Mars entry vehicle subject to uncertainties. A composite super twisting sliding mode control method based on finite-time disturbance observer is proposed for guidance law design. The proposed controller not only eliminates the effects of matched and mismatched disturbances due to uncertainties of atmospheric models and vehicle aerodynamics but also guarantees the continuity of control action. Numerical simulations are carried out on the basis of Mars Science Laboratory mission, where the results show that the proposed methods can improve the Mars entry guidance precision as compared with some existing guidance methods including PID and ADRC.

  19. Multi-scale modeling of fiber and fabric reinforced cement based composites

    Science.gov (United States)

    Soranakom, Chote

    With an increased use of fiber reinforced concrete in structural applications, proper characterization techniques and development of design guides are needed. This dissertation presents a multi-scale modeling approach for fiber and fabric reinforced cement-based composites. A micromechanics-based model of the yarn pullout mechanism due to the failure of the interfacial zone is presented. The effect of mechanical anchorage of transverse yarns is simulated using nonlinear spring elements. The yarn pullout mechanism was used in a meso-scale modeling approach to simulate the yarn bridging force in the crack evolution process. The tensile stress-strain response of a tension specimen that experiences distributed cracking can be simulated using a generalized finite difference approach. The stiffness degradation, tension stiffening, crack spacing evolution, and crack width characteristics of cement composites can be derived using matrix, interface and fiber properties. The theoretical models developed for fabric reinforced cement composites were then extended to cover other types of fiber reinforced concrete such as shotcrete, glass fiber reinforced concrete (GFRC), steel fiber reinforced concrete (SFRC), ferrocement and other conventional composite systems. The uniaxial tensile stress-strain response was used to formulate a generalized parametric closed-form solution for predicting flexural behavior of various composites at the macro-structural level. The flexural behaviors of these composites were modeled in a unified manner by means of a moment-curvature relationship based on the uniaxial material models. A variety of theoretical models were developed to address the various mechanisms including: an analytical yarn pullout model; a nonlinear finite difference fabric pullout model; a nonlinear finite difference tension model; closed-form solutions for strain-softening materials; closed-form solutions for strain-softening/hardening materials; and closed-form solutions for

  20. Base composition, selection, and phylogenetic significance of indels in the recombination activating gene-1 in vertebrates

    Directory of Open Access Journals (Sweden)

    Vences Miguel

    2009-12-01

    Full Text Available Abstract Background The Recombination Activating Proteins, RAG1 and RAG2, play a crucial role in the immune response in vertebrates. Among the nuclear markers currently used for phylogenetic purposes, Rag1 has especially enjoyed enormous popularity, since it successfully contributed to elucidating the relationships among and within a large variety of vertebrate lineages. We here report on a comparative investigation of the genetic variation, base composition, presence of indels, and selection in Rag1 in different vertebrate lineages (Actinopterygii, Amphibia, Aves, Chondrichthyes, Crocodylia, Lepidosauria, Mammalia, and Testudines through the analysis of 582 sequences obtained from Genbank. We also analyze possible differences between distinct parts of the gene with different type of protein functions. Results In the vertebrate lineages studied, Rag1 is over 3 kb long. We observed a high level of heterogeneity in base composition at the 3rd codon position in some of the studied vertebrate lineages and in some specific taxa. This result is also paralleled by taxonomic differences in the GC content at the same codon position. Moreover, positive selection occurs at some sites in Aves, Lepidosauria and Testudines. Indels, which are often used as phylogenetic characters, are more informative across vertebrates in the 5' than in the 3'-end of the gene. When the entire gene is considered, the use of indels as phylogenetic character only recovers one major vertebrate clade, the Actinopterygii. However, in numerous cases insertions or deletions are specific to a monophyletic group. Conclusions Rag1 is a phylogenetic marker of undoubted quality. Our study points to the need of carrying out a preliminary investigation on the base composition and the possible existence of sites under selection of this gene within the groups studied to avoid misleading resolution. The gene shows highly heterogeneous base composition, which affects some taxa in particular and