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Material Characteristics (material + characteristic)
Selected AbstractsStudy of the passive microwave RFID tag range using distance-dependent reflection coefficient over multipath channelMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2009Fu Wei Abstract The distance-dependent reflection coefficients are investigated based on a multi-ray model at microwave frequency bands. Tag range of passive microwave radio-frequency identification (RFID) systems is then calculated taking into account the tagged object material characteristic. Obtained values are verified through the precise simulations based on a 3-D physical finite element model. The results shown that the proposed method provides a good agreement than that obtained by existing methods. The analytical method can be used for the empirical tag range value to avoid reader collision while ensuring system reliability. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2266,2268, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24602 [source] New data for sandwich panels on the correlation between the SBI test method and the room corner reference scenarioFIRE AND MATERIALS, Issue 1 2005Jesper Axelsson Abstract Assessment of the fire behaviour of sandwich panels is continuously under discussion. The fire behaviour of these panels is a combination of material characteristics such as the core material and mechanical behaviour of the panels such as joints, dilations etc. The use of small or intermediate scale tests can be questioned for such types of products. Within the proposed European product standard for sandwich panels (prEN 14509) the intermediate scale test method SBI (EN 13823) has been suggested as the fire test method to certify panels. The standard does, however, use quite an artificial mounting procedure, which does not fully reflect the end-use conditions of the panels. In a previous research project conducted by Nordtest it was shown that the correlation between the SBI test method and both the ISO 9705 and ISO 13784 part 1 was insufficient. The test data produced for the SBI test method, however, did not use the above mentioned mounting technique. In this article new data for a number of products are added to the database using the mounting procedure of the product standard. The data are compared with the previous data and show that the mounting method of the product standard results in slightly more severe conditions but that there are still discrepancies with the full-scale test results. The data also show an unacceptable level of repeatability due to the fact that small dilations result in a wide variation of classification result. The new data together with the old data show once more that it is dangerous to make a fire safety assessment of a sandwich panel based on small or intermediate scale tests. Copyright © 2004 John Wiley & Sons, Ltd. [source] Shape-prediction of 3D PTFE Microstructures Fabricated by Synchrotron Radiation AblationIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 2 2010Mitsuhiro Horade Non-member Abstract This article describes the calculation of the predictions of the deformed shapes of three-dimensional polytetrafluoroethylene (PTFE) microstructures fabricated by direct etching with a synchrotron radiation (SR) light source. As PTFE is a remarkable material, there is a lot of expectation regarding its applications in various devices. We did research on establishing a highly accurate three-dimensional technology for microfabricating PTFE by using an SR-light source because we aimed at applying this material in future devices. We built a shape-prediction technique as part of this research. Since this technique had the advantage of predicting shapes without experimentation, both fabrication time and cost could be reduced. It is also a useful technique for investigating and clarifying processing mechanisms. We compared structures fabricated in an experiment and the shapes computed with shape-prediction. The shape-prediction results were mostly in agreement with those from the experiment. As PTFE demonstrated excellent material characteristics, especially in its resistance to chemicals, it should be possible to use it in the fabrication of micro total analysis systems (µ-TAS) for biomedical applications. We expect that these applications will benefit from (based on) the designs which are predicted utilizing this calculation method. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Bioaccessibility studies of ferro-chromium alloy particles for a simulated inhalation scenario: A comparative study with the pure metals and stainless steelINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 3 2010Klara Midander Abstract The European product safety legislation, REACH, requires that companies that manufacture, import, or use chemicals demonstrate safe use and high level of protection of their products placed on the market from a human health and environmental perspective. This process involves detailed assessment of potential hazards for various toxicity endpoints induced by the use of chemicals with a minimum use of animal testing. Such an assessment requires thorough understanding of relevant exposure scenarios including material characteristics and intrinsic properties and how, for instance, physical and chemical properties change from the manufacturing phase, throughout use, to final disposal. Temporary or permanent adverse health effects induced by particles depend either on their shape or physical characteristics, and/or on chemical interactions with the particle surface upon human exposure. Potential adverse effects caused by the exposure of metal particles through the gastrointestinal system, the pulmonary system, or the skin, and their subsequent potential for particle dissolution and metal release in contact with biological media, show significant gaps of knowledge. In vitro bioaccessibility testing at conditions of relevance for different exposure scenarios, combined with the generation of a detailed understanding of intrinsic material properties and surface characteristics, are in this context a useful approach to address aspects of relevance for accurate risk and hazard assessment of chemicals, including metals and alloys and to avoid the use of in vivo testing. Alloys are essential engineering materials in all kinds of applications in society, but their potential adverse effects on human health and the environment are very seldom assessed. Alloys are treated in REACH as mixtures of their constituent elements, an approach highly inappropriate because intrinsic properties of alloys generally are totally different compared with their pure metal components. A large research effort was therefore conducted to generate quantitative bioaccessibility data for particles of ferro-chromium alloys compared with particles of the pure metals and stainless steel exposed at in vitro conditions in synthetic biological media of relevance for particle inhalation and ingestion. All results are presented combining bioaccessibility data with aspects of particle characteristics, surface composition, and barrier properties of surface oxides. Iron and chromium were the main elements released from ferro-chromium alloys upon exposure in synthetic biological media. Both elements revealed time-dependent release processes. One week exposures resulted in very small released particle fractions being less than 0.3% of the particle mass at acidic conditions and less than 0.001% in near pH-neutral media. The extent of Fe released from ferro-chromium alloy particles was significantly lower compared with particles of pure Fe, whereas Cr was released to a very low and similar extent as from particles of pure Cr and stainless steel. Low release rates are a result of a surface oxide with passive properties predominantly composed of chromium(III)-rich oxides and silica and, to a lesser extent, of iron(II,III)oxides. Neither the relative bulk alloy composition nor the surface composition can be used to predict or assess the extent of metals released in different synthetic biological media. Ferro-chromium alloys cannot be assessed from the behavior of their pure metal constituents. Integr Environ Assess Manag 2010;6:441,455. © 2009 SETAC [source] Numerical modelling of anisotropy and eddy current effects in ferromagnetic laminations using a co-energy formulationINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 5 2001L. R. Dupré Abstract The paper deals with a numerical model for the evaluation of electromagnetic fields in one steel lamination under the influence of a rotating magnetic flux, taking into account anisotropy effects. For this purpose a detailed material model, described by a differential permeability tensor, is included in the macroscopic electromagnetic field calculations in one lamination. Here, by geometrical and physical considerations, the governing Maxwell equations are reduced to a system of parabolic PDEs for the components of the magnetic field vector, under appropriate boundary and initial conditions. We present a suitable numerical approximation based upon a finite element,finite difference method, which properly takes into account the material characteristics. The study leads to a more realistic numerical modelling of the electromagnetic phenomena inside electric and magnetic conducting laminations due to anisotropy effects. Numerical results are compared with those from simplified analytical formulae. Copyright © 2001 John Wiley & Sons, Ltd. [source] Building the Other, Constructing Ourselves: Spatial Dimensions of International Humanitarian ResponseINTERNATIONAL POLITICAL SOCIOLOGY, Issue 3 2008Lisa Smirl Humanitarian reconstruction after a large-scale natural disaster has become a key site of international politics; a site where global assumptions, relationships, and responsibilities are negotiated, solidified and questioned. While post-crisis response strategies and institutional practices have strong spatial and material characteristics, these are rarely considered as significant,either to the reconstruction effort, or to international politics more generally. This article identifies and examines the "auxiliary space" created by the everyday practices of international aid workers and asks whether its effects may lead to unanticipated and potentially transformative outcomes not only for the reconstruction effort, but also for global North-South relations at large. The article concludes that post-crisis reconstruction sites may offer both cautionary and emancipatory potential for the evolution of international relations. [source] Effect of crosslinking, remelting, and aging on UHMWPE damage in a linear experimental wear modelJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 7 2007Suzanne A. Maher Abstract The objective of this study was to establish the effect of postirradiation melting as a function of irradiation dose on the wear behavior and material characteristics of ultrahigh molecular weight polyethylene. Our hypothesis was that a low dose of irradiation followed by melting would have the same improved wear performance as is found with higher doses of irradiation, but without the disadvantages associated with reduced fracture toughness. The hypothesis was tested by measuring the wear performance (wear track area, incidence of pitting and delamination) in a linear doubly curved-on-flat cyclic test, material behavior (elastic modulus, fracture toughness), and aging response (density changes through the thickness) of the following materials: elevated crosslinked groups,radiated at 25, 65, and 120 kGy, melted, sterilized and aged; a melted group,melted, sterilized, and aged; and a control group,sterilized and aged. Our findings suggest that postirradiation melting, not the irradiation dose, dominates the material property changes and wear response. Melting ensured reduced modulus and therefore decreased contact stresses, superior wear performance, and good resistance to aging, even after low levels of irradiation (25 kGy). The low modulus of the 25 kGy elevated crosslinked group, coupled with increased fracture toughness compared to samples irradiated at higher doses and a resistance to aging not found in the melted group, support our hypothesis. A low dose of irradiation followed by heat treatment has the same beneficial effects in terms of improved wear performance, but without the disadvantages of reduced fracture toughness found with higher doses of irradiation. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:849,857, 2007 [source] Verarbeitung hochfester Aluminiumlegierungen durch umformende VerfahrenMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 7 2009R. Neugebauer ECAP; rolling; extrusion; incremental forming Abstract Basierend auf experimentell ermittelten Werkstoffkennwerten wird ein Vergleich des Umformverhaltens der beiden Aluminiumlegierungen im Anlieferungszustand (EN AW-7075 T651) sowie im modifizierten Zustand (EN AW-7075 ECAP) bei der Verarbeitung mit herkömmlichen Umformverfahren (Walzen, Fließpressen) angestellt. Zudem werden die Verfahrensgrenzen des Umformgrades durch Variation der Werkzeuggeometrien experimentell lokalisiert. Dabei ist ebenfalls Untersuchungsgegenstand, den Einfluss des Verfahrens auf das Umformvermögen zu ermitteln. Davon ausgehend werden Werkzeugkonzepte entwickelt, die eine Umformung des hochfesten Aluminiums unter Erzeugung von hydrostatischen Druckzuständen in der Umformzone ermöglichen. Sowohl die Simulation als auch die Versuche zeigten Materialversagen der ultrafeinkörnigen Werkstoffe beim Fließpressen. Das Walzen als inkrementelles Umformverfahren ermöglichte hingegen eine schadensfreie Herstellung der Werkstücke. Forming of high-strength aluminium alloys A comparison of the forming behavior of both aluminum alloys in as-received condition (EN AW-7075 T651) as well as modified condition (EN AW-7075 ECAP) when processed with conventional forming processes (rolling, extrusion) is conducted on the base of experimentally determined material characteristics. In the following the process limits of the true strain are located by variegating the tool geometry. The influence of the manufacturing method on the plasticity is also a subject matter to analysis. Based upon the outcome of this analysis special tool conceptions are being developed, which allow the forming of highest-strength aluminum while creating hydrostatical pressure states in the deformed zone. Both simulation and experiments showed material failure of the ultra-fine-grained materials when extruded whereas rolling, being the incremental forming process, allowed damage-free manufacturing of components. [source] PETROGRAPHY AND PROVENANCE INTERPRETATION OF THE STONE MOULDS FOR BRONZE DAGGERS FROM THE GALDONG PREHISTORIC SITE, REPUBLIC OF KOREA*ARCHAEOMETRY, Issue 1 2010C. H. LEE This paper presents material characteristics and raw material provenance of the stone moulds for bronze slender daggers from Galdong. This type of bronze dagger is uniquely distributed in the Korean Peninsula and these stone moulds were the first to be found by excavation. The stone moulds were made of igneous hornblendite with course-grained holocrystalline textures. Based on petrological, mineralogical and geochemical characteristics, the original rock materials of the moulds were inferred to be derived from the Jangsu or Namwon areas which are about 50 km away from the excavation site. It is a notable achievement that this provenance study confirmed the domestic production of Korean-styled daggers. [source] | |||||||||||||