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Luísa C. Sousa Catarina F. Castro Carlos C. António Hipólito Sousa 《Construction and Building Materials》2011,25(5):2254-2262
The aim of this work is to find an economic single leaf masonry wall for the building construction industry with minimised heat loss through the envelope. Lightweight aggregate concrete has the potential to offer weight reduction as well as good thermal and acoustic properties without significantly compromising the wall structural properties. The article presented here describes a search for the optimal topology of lightweight concrete masonry units according to normal thermal demands. The wall performance is measured through thermal transmittance values. The thermal behaviour of the units is calculated using three-dimensional finite element simulations. The developed topology optimisation method considers a numerical evolutionary algorithm iterating over the direct analysis performed by the finite element method. The obtained optimised topology unit will contribute towards sustainability and energy saving needs of today’s building construction industry. 相似文献
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Many common protective relays used in protection of power equipment are sensitive to phase sequence rotation of the utility supply. A method of analyzing the relay response to the respective phase rotation and other possible variables is described. It is demonstrated that phase rotation usually does not affect zero-sequence polarized relays. The technique is an exercise in voltage and current phasors, maximum torque lines of polarized relays, and the possible effect of system power factor. The following relays are discussed: directional power relay (IEEE Protective Device No.32) as used to protect prime movers on induction and synchronous generators from being motored by the generator due to loss of mechanical power; directional VAr relay (IEEE Protective Device No.55) as used to protect synchronous motors and synchronous generators from receiving VArs from the external power system due to loss of field excitation; directional current phase relay (IEEE Protective Device No.67) as used to detect reverse current flow into a power system from another source due to a system phase fault; and directional current ground relay (IEEE Protective Device No.67N) as used to detect reverse ground current flow into a power system from another source due to a system ground fault 相似文献
97.
J. F. Aldana M. Roldn‐Castro I. Navas M. M. Roldn‐García M. Hidalgo‐Conde O. Trelles 《Software》2006,36(14):1585-1604
In this work we present an architecture for XML‐based mediator systems and a framework for helping systems developers in the construction of mediator‐services for the integration of heterogeneous data sources. A unique feature of our architecture is its capability to manage (proprietary) user's software tools and algorithms, modelled as Extended Value Added Services (EVASs), and integrated in the data flow. The mediator offers a view of the system as a single data source where EVASs are readily available for enhancing query processing. A Web‐based graphic interface has been developed to allow dynamic and flexible EVASs inter‐connection, thus creating complex distributed bioinformatics machines. The feasibility and usefulness of our ideas has been validated by the development of a mediator system (Bio‐Broker) and by a diverse set of applications aimed at combining gene expression data with genomic, sequence‐based and structural information, so as to provide a general, transparent and powerful solution that integrates data analysis tools and algorithms. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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A. D. Arnold P. E. Castro T. K. Hatwar M. V. Hettel P. J. Kane J. E. Ludwicki M. E. Miller M. J. Murdoch J. P. Spindler S. A. Van Slyke K. Mameno R. Nishikawa T. Omura S. Matsumoto 《Journal of the Society for Information Display》2005,13(6):525-535
Abstract— A full‐color AMOLED display with an RGBW color filter pattern has been fabricated. Displays with this format require about one‐half the power of analogous RGB displays. RGBW and RGB 2.16‐in.‐diagonal displays with average power consumptions of 180 and 340 mW, respectively, were characterized for a set of standard digital still camera images at a luminance of 100 cd/m2. In both cases, a white‐emitting AMOLED was used as the light source, and standard LCD filters were used to provide the R, G, and B emission. The color gamuts of these displays were identical and the higher overall efficiency of the RGBW format results from two factors. First, a large fraction of a typical image is near neutral in color and can be reproduced using the white sub‐pixel. Second, the white sub‐pixel in an RGBW AMOLED display is highly efficient because of the absence of any color filter. The efficiency of these displays can be further enhanced by choosing a white emitter optimized to the target display white point (in this case D65). A two‐emission layer configuration based upon separate yellow and blue‐emitting regions is shown to be well suited for both the RGBW and RGB formats. 相似文献
99.
A. H. Castro Neto 《Journal of Superconductivity》2000,13(6):913-916
We propose a model for a spatially modulated collective state of superconducting cuprates in which the electronic properties vary locally in space. In this model, the regions of higher hole density (called stripes) are described as Luttinger liquids and the regions of lower density (antiferromagnetic ladders) as an interacting bosonic gas of
hole pairs. We show that the transition to the superconducting state is topologic and driven by decay processes among these elementary excitations in the presence of vibrations. 相似文献
100.
A.L.F. de Barros A. Medina F. Zappa J.M. Pereira E. Bessa M.H.P. Martins L.F.S. Coelho W. Wolff N.V. de Castro Faria 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2006,560(2):219-223
We measured the vapour pressure of several DNA and RNA bases—uracil, adenine, guanine, thymine and cytosine—in the 300–450 K range. In each case the sample mass loss rate was measured as function of temperature with a simple setup consisting of a commercial film deposition system and a homemade oven. Afterwards vapour pressure values were extracted from these data using the Knudsen effusion method. Sublimation enthalpy values, obtained from vapour pressure data by applying the Clausius–Clapeyron equation, are in very good agreement with literature values. The results suggest that crystal-based film thickness monitors may be useful in on-line cross-section measurements, monitoring the gas target thickness. They also show the viability of using this oven for producing a biomolecular gas target. 相似文献