985 resultados para Mixture method
Resumo:
The dynamic interaction between building systems and external climate is extremely complex, involving a large number of difficult-to-predict variables. In order to study the impact of global warming on the built environment, the use of building simulation techniques together with forecast weather data are often necessary. Since all building simulation programs require hourly meteorological input data for their thermal comfort and energy evaluation, the provision of suitable weather data becomes critical. Based on a review of the existing weather data generation models, this paper presents an effective method to generate approximate future hourly weather data suitable for the study of the impact of global warming. Depending on the level of information available for the prediction of future weather condition, it is shown that either the method of retaining to current level, constant offset method or diurnal modelling method may be used to generate the future hourly variation of an individual weather parameter. An example of the application of this method to the different global warming scenarios in Australia is presented. Since there is no reliable projection of possible change in air humidity, solar radiation or wind characters, as a first approximation, these parameters have been assumed to remain at the current level. A sensitivity test of their impact on the building energy performance shows that there is generally a good linear relationship between building cooling load and the changes of weather variables of solar radiation, relative humidity or wind speed.
Resumo:
Welding system has now been concentrated on the development of new process to achieve cost savings, higher productivity and better quality in manufacturing industry. Discrete alternate supply of shielding gas is a new technology that alternately supplies the different kinds of shielding gases in weld zone. As the newdevelopedmethods compared to the previous generalwelding with a mixing supply of shielding gas, it cannot only increase thewelding quality, but also reduce the energy by 20% and the emission rate of fume. As a result, under thesamewelding conditions,comparedwith thewelding by supplying pure argon, argon + 67% helium mixture by conventional method and thewelding by supplying alternately pure argon and pure helium by alternate method showed the increased welding speed. Also, the alternate method showed the same welding speed with argon + 67% helium mixture without largely deteriorating of weld penetration. The alternate method with argon and helium compared with the conventional methods of pure argon and argon + 67% helium mixture produced the lowest degree of welding distortion.
Resumo:
Recently, unlike conventional method in supplying shielding gas, a newly method which alternately supplies different kinds of shielding gases in weld zone is developed and partly commercialized. However, literature related to the present status of the technology in the actual weld field is very scant. To give better understand on this technology, this study was performed. Compared with conventional gas supply method, the variations of weld porosity and weld shape in aluminum welding with alternate supply method of pure argon and pure helium were compared with conventional gas supply method with pure argon and argon + 67%helium mixture, respectively. As a result, compared with the welding by supplying pure argon and argon + 67%helium mixture by conventional method, the welding by supplying alternately pure argon and pure helium, produced lower degree of weld porosity and deeper and broader weld penetration profile.
Resumo:
For certain continuum problems, it is desirable and beneficial to combine two different methods together in order to exploit their advantages while evading their disadvantages. In this paper, a bridging transition algorithm is developed for the combination of the meshfree method (MM) with the finite element method (FEM). In this coupled method, the meshfree method is used in the sub-domain where the MM is required to obtain high accuracy, and the finite element method is employed in other sub-domains where FEM is required to improve the computational efficiency. The MM domain and the FEM domain are connected by a transition (bridging) region. A modified variational formulation and the Lagrange multiplier method are used to ensure the compatibility of displacements and their gradients. To improve the computational efficiency and reduce the meshing cost in the transition region, regularly distributed transition particles, which are independent of either the meshfree nodes or the FE nodes, can be inserted into the transition region. The newly developed coupled method is applied to the stress analysis of 2D solids and structures in order to investigate its’ performance and study parameters. Numerical results show that the present coupled method is convergent, accurate and stable. The coupled method has a promising potential for practical applications, because it can take advantages of both the meshfree method and FEM when overcome their shortcomings.
Resumo:
In this article I outline and demonstrate a synthesis of the methods developed by Lemke (1998) and Martin (2000) for analyzing evaluations in English. I demonstrate the synthesis using examples from a 1.3-million-word technology policy corpus drawn from institutions at the local, state, national, and supranational levels. Lemke's (1998) critical model is organized around the broad 'evaluative dimensions' that are deployed to evaluate propositions and proposals in English. Martin's (2000) model is organized with a more overtly systemic-functional orientation around the concept of 'encoded feeling'. In applying both these models at different times, whilst recognizing their individual usefulness and complementarity, I found specific limitations that led me to work towards a synthesis of the two approaches. I also argue for the need to consider genre, media, and institutional aspects more explicitly when claiming intertextual and heteroglossic relations as the basis for inferred evaluations. A basic assertion made in this article is that the perceived Desirability of a process, person, circumstance, or thing is identical to its 'value'. But the Desirability of anything is a socially and thus historically conditioned attribution that requires significant amounts of institutional inculcation of other 'types' of value-appropriateness, importance, beauty, power, and so on. I therefore propose a method informed by critical discourse analysis (CDA) that sees evaluation as happening on at least four interdependent levels of abstraction.
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The determination of the most appropriate procurement method for capital works projects is a challenging task for the Department of Housing and Works (DHW) and other Western Australian State Government Agencies because of the array of assessment criteria that are considered and the procurement methods that are available. A number of different procurement systems can be used to deliver capital works projects such a traditional, design and construct and management. Sub-classifications of these systems have proliferated and continue to emerge in response to market demands. The selection of an inappropriate procurement method may lead to undesirable project outcomes. To facilitate DHW in selecting an appropriate procurement method for its capital works projects, a six step procurement method selection process is presented. The characteristics of the most common forms of procurement method used in Australia are presented. Case studies where procurement methods have been used for specific types of capital works in Western Australia are offered to provide a reference point and learning opportunity for procurement method selection.
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This article reports an enhanced solvent casting/particulate (salt) leaching (SCPL) method developed for preparing three-dimensional porous polyurethane (PU) scaffolds for cardiac tissue engineering. The solvent for the preparation of the PU scaffolds was a mixture of dimethylformamide (DFM) and tetrahydrofuran (THF). The enhanced method involved the combination of a conventional SCPL method and a step of centrifugation, with the centrifugation being employed to improve the pore uniformity and the pore interconnectivity of scaffolds. Highly porous three-dimensional scaffolds with a well interconnected porous structure could be achieved at the polymer solution concentration of up to 20% by air or vacuum drying to remove the solvent. When the salt particle sizes of 212-295, 295-425, or 425-531 µm and a 15% w/v polymer solution concentration were used, the porosity of the scaffolds was between 83-92% and the compression moduli of the scaffolds were between 13 kPa and 28 kPa. Type I collagen acidic solution was introduced into the pores of a PU scaffold to coat the collagen onto the pore walls throughout the whole PU scaffold. The human aortic endothelial cells (HAECs) cultured in the collagen-coated PU scaffold for 2 weeks were observed by scanning electron microscopy (SEM). It was shown that the enhanced SCPL method and the collagen coating resulted in a spatially uniform distribution of cells throughout the collagen-coated PU scaffold.