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Zone Size (zone + size)
Selected AbstractsMeasuring the Plastic Zone Size by Orientation Gradient Mapping (OGM) and Electron Channeling Contrast Imaging (ECCI)ADVANCED ENGINEERING MATERIALS, Issue 1-2 2007T. Welsch Abstract For the local investigation of plastic deformation mechanisms non-destructive methods are needed to image the distribution of dislocations and to measure dislocation densities. Additionally these methods should be usable in situ. Therefore the well known methods EBSD and ECCI are improved by an appropriate processing of the measured data. The resulting two new techniques OGM and ECCI-plus are validated in detail for two complex sets of experiments. Both techniques are used to image plastic deformation zones and to measure the size of plastic zones on a macro scale (hardness indents) as well as on a micro scale (crack tips) as demonstrated in this paper. Additionally OGM gives even quantitative data of the degree of deformation. The capability of both methods is discussed in detail and it is shown that they are independent from the topography which is critically surveyed. [source] Numerical modelling of dynamic consolidation on granular soilsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 12 2008S. López-Querol Abstract The application of Pastor,Zienkiewicz constitutive model for sands to dynamic consolidation problems is presented in this paper. This model is implemented in a coupled code formulated in terms of displacements for both solid and fluid phases (u,w formulation), which is firstly compared with u,pw formulation for some simple examples. Its range of validity, previously established for elastic problems and harmonic loading, is explored. Once the suitability of the u,w formulation has been ascertained for this kind of dynamic problems in soils, one- and two-dimensional (plane strain) dynamic consolidation numerical examples are provided, aiming to give some light into the physics of this ground improvement technique. A ,wave of dryness', observed at the soil surface during the impact in field cases, is numerically reproduced and justified. Some hints on the influence of the loading zone size are also given. Copyright © 2007 John Wiley & Sons, Ltd. [source] Effect of certain bioactive plant extracts on clinical isolates of ,-lactamase producing methicillin resistant Staphylococcus aureusJOURNAL OF BASIC MICROBIOLOGY, Issue 2 2005Farrukh Aqil Ethanolic extracts and some fractions from 10 Indian medicinal plants, known for antibacterial activity, were investigated for their ability to inhibit clinical isolates of ,-lactamase producing methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA). Synergistic interaction of plant extracts with certain antibiotics was also evaluated. The MRSA test strains were found to be multi-drug resistant and also exhibited high level of resistance to common ,-lactam antibiotics. These strains produced ,-lactamases, which hydrolyze one or other ,-lactam antibiotics, tested. The extract of the plants from Camellia sinensis (leaves), Delonix regia (flowers), Holarrhena antidysenterica (bark), Lawsonia inermis (leaves), Punica granatum (rind), Terminalia chebula (fruits) and Terminalia belerica (fruits) showed a broad-spectrum of antibacterial activity with an inhibition zone size of 11 mm to 27 mm, against all the test bacteria. The extracts from the leaves of Ocimum sanctum showed better activity against the three MRSA strains. On the other hand, extracts from Allium sativum (bulb) and Citrus sinensis (rind) exhibited little or no activity, against MRSA strains. The antibacterial potency of crude extracts was determined in terms of minimum inhibitory concentration (MIC) by the tube dilution method. MIC values, of the plant extracts, ranged from 1.3 to 8.2 mg/ml, against the test bacteria. Further, the extracts from Punica granatum and Delonix regia were fractionated in benzene, acetone and methanol. Antibacterial activity was observed in acetone as well as in the methanol fractions. In vitro synergistic interaction of crude extracts from Camellia sinensis, Lawsonia inermis, Punica granatum, Terminalia chebula and Terminalia belerica was detected with tetracycline. Moreover, the extract from Camellia sinensis also showed synergism with ampicillin. TLC of the above extracts revealed the presence of major phytocompounds, like alkaloids, glycosides, flavonoids, phenols and saponins. TLC-bioautography indicated phenols and flavonoids as major active compounds. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A New Analytical Model for Estimation of Scratch-Induced Damage in Brittle SolidsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2007Xiaoning Jing Scratch tests are of fundamental interest both for understanding machining-induced damage and for evaluating the scratch resistance of brittle materials. An improved blister field model for the scratch process is proposed where the blister field strength is explicitly determined in terms of the material properties, loading conditions, and geometry of the scratch tool. Additionally, one new expanding cylindrical cavity model is implemented to estimate the plastic zone size surrounding the scratch groove. A quantitative evaluation of the damage zone size is conducted by combining the above two models. The predicted damage zone sizes are in good agreement with the results available elsewhere in literature. [source] The effect of treatment zone diameter in hyperopic orthokeratologyOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 6 2009Paul Gifford Abstract Purpose:, To investigate the time course of treatment zone (TZ) diameter changes in hyperopic orthokeratology (OK) lens wear from 1 h in the open eye through to seven nights in the closed eye. Methods:, Twelve subjects were fitted with rigid hyperopic OK lenses. Lenses were worn in the open eye for 1 h then one night in the closed eye, separated by a washout period of 4 days. Changes in best corrected visual acuity (BCVA) and corneal topography (Medmont E-300) were measured on lens removal. The TZ, comprising the central steepened zone (CSZ) and surrounding annular flattened zone (AFZ), was measured from corneal topography. Subsequently, ten subjects wore the same lens design overnight for seven nights, and measurements were taken on lens removal and 8 h later on Days 1 and 7. Results:, Both CSZ and AFZ were apparent after 1 h of hyperopic OK lens wear. CSZ decreased while AFZ increased with longer periods of lens wear. BCVA reduced with longer periods of lens wear and was associated with decreasing CSZ (r = ,0.866, p < 0.001) and increasing AFZ (r = 0.447, p < 0.05). Conclusions:, The association of changes of treatment zone size with reductions in BCVA suggests that increasing CSZ may lead to better visual outcomes in hyperopic OK. [source] Vereinfachtes Flächenerfassungsmodell für MehrzonenbilanzenBAUPHYSIK, Issue 3 2009Markus Lichtmeß Dipl.-Ing. Berechnungsverfahren; Technische Regelwerke Abstract Bei der energetischen Bilanzierung nach DIN V 18599 müssen Gebäude aufgrund unterschiedlicher Nutzungseigenschaften zoniert werden. Auch die Gebäudehüllfläche wird nach diesen Kriterien aufgeteilt und den Zonen zur weiteren Berechnung zugewiesen. In der Praxis ist die Aufteilung der inneren Zonenumschließungs- und der äußeren Gebäudehüllfläche mit einem hohen Arbeitsaufwand verbunden. Etwa 50 % der Zeit wird für die Zonierung und die Ermittlung dieser Flächen- und Bauteileigenschaften benötigt. Zur Verringerung des Zeitaufwandes wurde eine Methode entwickelt, mit welcher die Gebäudehülle ähnlich dem 1-Zonen-Modell erfasst werden kann. Die Hüllfläche wird den Zonen vereinfacht zugeordnet, sodass die eigentliche Berechnung in der Mehrzonenbilanz erfolgen kann. Dies bringt wesentliche Vorteile bei der Auslegung und Optimierung nachgeschalteter Anlagentechnik mit sich. Die Verteilung der thermischen Hüllflächen erfolgt bei diesem vereinfachten Verfahren in Abhängigkeit von der Zonengröße und kann über ein Wichtungsverfahren beeinflusst bzw. korrigiert werden. Untersuchungen an mehreren Gebäuden haben gezeigt, dass die Flächenverteilung mit einer guten Genauigkeit eingesetzt werden kann, wobei eine "intelligente" Zuteilung über ein Wichtungsverfahren erforderlich ist. Die Zeitersparnis bei Anwendung der Vereinfachungen beträgt etwa 30 %. Bei komplexeren, vielzonigen Gebäuden ist die Einsparung tendenziell höher einzuschätzen. Das Verfahren erlaubt, alle Bauteilflächen detailliert auf Zonenebene nachzueditieren und somit die Möglichkeit, das Gebäudemodell planungsbegleitend zu konkretisieren. So kann die Berechnung im Laufe der Projektbearbeitung immer weiter präzisiert werden, wodurch die Berechnungsgenauigkeit und die Optimierungsmöglichkeiten gesteigert werden. Diese Vereinfachungen sollen zukünftig in der Luxemburger EnEV zur energetischen Bewertung von neu zu errichtenden Nichtwohngebäuden nach DIN V 18599 Anwendung finden. A simplified surface area calculation and zoning model for energy performance assessment of buildings. According to the DIN V 18599 energy performance assessment, buildings have to be divided into zones depending on their utilisation. The same zoning applies to the building envelope where the segments are being allocated to the individual zones. In engineering practice about 50% of the work is required for zoning, calculating surface areas and evaluating the properties of building envelope components. In order to reduce the time needed for these efforts a methodology similar to the single zone model has been developed. To carry out the multiple zone calculation the building envelope is being split and allocated to the individual zones in a simplified way. This as well provides a significant advantage for the dimensioning and optimisation of the related HVAC and lighting systems. Within the simplified calculation, the allocation of the building envelope is carried out in dependence of the zone size and corrected with a weighting factor if needed. The analysis of several buildings has shown that the simplified method can be applied with sufficient accuracy. The weighting factors are however necessary. By implementing this simplification the time expenditure to calculate a building is reduced by more or less 30%. This reduction tends to be even more important when dealing with complex buildings which have a high number of zones. The methodology enables building components to be edited by zones and hereby gives the opportunity to easily modify the design during the course of the planning. As the project develops, the calculations can be more detailed thereby increasing the precision of the calculation. In the near future this methodology will be implemented in the Luxembourg energy saving ordinance (EnEV) for the energy performance assessment of non residential buildings. [source] Analysis of stirred tanks with two-zone modelsAICHE JOURNAL, Issue 10 2009Ville Alopaeus Abstract Stirred tank turbulence and fluid flow characteristics are analyzed based on a two-zone model. Instead of using the zonal model for stirred tank performance prediction as often proposed in the literature, the zoning is used here as a tool for mixing analysis. A systematic zoning approach is proposed, where the tank is divided into two nested regions. By gradually increasing the inner zone volume, continuous curves can be obtained for turbulent energy dissipation distribution and pumping numbers between the zones as functions of the zone sizes. It is shown here that these curves can be used as a powerful tool for visualizing stirred tank performance. They can be used, e.g., in impeller performance comparisons and analysis of mixing characteristics with changing rheology, or to examine various numerical aspects related to stirred tank CFD modeling. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Determining the zone of reflection for posterior corneal surface comparison phakometryOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2009Andrew Carkeet Abstract Although comparison phakometry has been used by a number of studies to measure posterior corneal shape, these studies have not calculated the size of the posterior corneal zones of reflection they assessed. This paper develops paraxial equations for calculating posterior corneal zones of reflection, based on standard keratometry equations and equivalent mirror theory. For targets used in previous studies, posterior corneal reflection zone sizes were calculated using paraxial equations and using exact ray tracing, assuming spherical and aspheric corneal surfaces. Paraxial methods and exact ray tracing methods give similar estimates for reflection zone sizes less than 2 mm, but for larger zone sizes ray tracing methods should be used. [source] | |||||||||||||