Natural convection inside dome shaped enclosures

In the present paper the analysis of heat transfer and free convective motion have been carried out numerically for dome shaped enclosures. The solution method is based on the finite element technique with the frontal solver and is used to examine the flow parameters and the heat transfer characteristics inside dome shaped enclosures of various offsets. In formulating the solution a general conic equation is considered to represent the dome of circular, elliptical, parabolic and hyperbolic shapes. The numerical results indicate that the circular and elliptical shapes of dome give higher heat transfer rate and offset of the dome effects convective heat transfer quite significantly. However, beyond 0.3 top dome offset, the change in overall heat transfer rate is not significant. In addition, the convective phenomenon influenced by a dome shaped cover results in establishing a secondary core region even at a moderate Rayleigh number when compared with an equivalent rectangular enclosure. A good comparison between the present numerical predictions and the previous published data is achieved.

Correct weight? analysing Australian football through a derivative global or cultural cringe model

The application of a 'global' model, in practice usually British or American, and generalised sociological concepts to a particular sport and its social and cultural context is not always appropriate. In Australian academia, the custom is particularly appealing, due to the Australian colonial 'cultural cringe', the pattern of automatic deference to overseas (termed 'international') knowledge. This article argues that 'Fresh Prince of Coloma! Dome: Indigenous Logic in the AFL' (Football Studies, 8(1), 2005) inappropriately applies American sociological, and American football, logic to the indigenous Australian game Australian football, which differs in character both as a game and in its social, cultural and political context. The three researchers do not take account of the factors of height and weight in Australian football, and the average size of Aboriginal players, and of the relationship between speed and strength in the game as strategies and tactics change. Both omissions constitute fundamental flaws. American football and sports sociology's ideas of 'central position theory', with a suggestion of underlying racism, is of limited relevance to Australian football. It is also possible that the American sitcom, Fresh Prince of Bel Air, was neither a helpful muse nor a suitable metaphor for research into this subj ect. In Australian football, a game in which few 'central positions' are crucial and in which 'leadership positions' can be found in many parts of the ground, including the half-back flank and the wing, neither size nor position are the only major determinants of significance in the team.

Superplasticity and cavitation of recycled AZ31 magnesium alloy fabricated by solid recycling process

Superplastic behaviour of Mg-alloy AZ31 was investigated to clarify the possibility of its use for superplastic forming (SPF) and to accurately evaluate material characteristics under a biaxial stress by utilizing a multi-dome test. The material characteristics were evaluated under three different superplastic temperatures , 643, 673, and 703 K in order to determine the most suitable superplastic temperature. Finite Element Method (FEM) simulation of rectangular pan forming was carried out to predict the formability of the material into a complex shape. The superplastic material properties are used for the simulation of a rectangular pan. Finally, the simulation results are compared with the experimental results to determine the accuracy of the superplastic material characteristics. The experimental results revealed that the m values are greater than 0.3 under the three superplastic temperatures, which is indicative of superplasticity. The optimum superplastic temperature is 673 K, at which a maximum m value and no grain growth were observed. The results of the FEM simulation revealed that certain localized thinning occurred at the die entrance of the deformed rectangular pan due to the insufficient ductility of the material. The simulation results also showed that the optimum superplastic temperature of AZ31 is 673 K.

Natural convection in domed porous enclosures : non-darcian flow

The natural-convection flow and associated heat transfer in a fluid-saturated porous medium have been investigated using the generalized porous medium approach for a dome-shaped enclosure. Many new features have been predicted with the connective heat transfer and the shape of the top dome cover. The solutions are obtained for a wide range of Darcy and Rayleigh numbers for different offsets and eccentricities of the top dome covers. The detailed parametric study reveals that there is a significant change in heat transfer rate when the offset is between 0.2 and 0.4. Different shapes of conic section, such as circular, elliptical, parabolic, and hyperbolic are used for the top dome cover, and their effects on natural convection and heat transfer rates are studied.

A non-darcian numerical modeling in domed enclosures filled with heat-generating porous media

Numerical study of the natural-convection flow and heat transfer in a dome-shaped, heat-generating, porous enclosure is considered. The general conic equation for the top dome is used to consider various conical top sections such as circular, elliptical, parabolic, and hyperbolic. The individual effect of fluid Rayleigh, Darcy, and heat-generating parameters on flow patterns and heat transfer rates are analyzed and presented. The predicted results show that the heat-generating parameter has the most significant contribution toward the growth of bicellular core flow. Moreover, there is significant change in temperature distribution in comparison to rectangular enclosures, due to the existence of the domed-shape top adiabatic cover. The results also show that, regardless of Darcy and Rayleigh values, a flat adiabatic top cover tends to yield the highest value of Nusselt number, followed by circular, elliptical, parabolic, and hyperbolic top covers, respectively.

Numerical investigation of natural convection inside complex enclosures

In this article, the analyses of heat transfer and free convective motion have been carried out numerically for various structures. The solution is based on a finite element method with the frontal solver to examine the flow parameters and heat transfer characteristics. Several dome configurations--such as flat, inclined, and dome shapes--are considered for the top of the enclosure. A general conic equation is considered to represent the dome as circular, elliptical, parabolic, or hyperbolic shape. The findings from this study indicate that the convective phenomenon is greatly influenced by the shape of the top cover dome and tends to form a secondary core even at a moderate Rayleigh number when compared with an equivalent rectangular enclosure. In addition, the circular and elliptical shapes of the dome give higher heat transfer rate. The effect of various "offset" of the dome and inclined roof on convective heat transfer is also found to be quite significant. However, beyond 0.3 of offset of the top cover for the dome and inclined roof, the change in overall heat transfer rate is minimal. The heat transfer coefficients of dome shaped and inclined roof enclosures are given and discussed.

Study on the visual performance of a traditional residential neighborhood in old Cairo

Traditional dwellings located in the hot arid zones of the Arabian regions are well known for their sensitive architectural response to the region’s climatic conditions and socio-cultural norms. The majority of these dwellings are well recognized for their courtyard arrangement and perforated fenestration system that evolved to control the harsh solar, climatic conditions without compromising the aesthetic quality of space and occupants’ wellbeing. However, the unique visual characteristics of these structures cannot be fully appreciated by assessing the visual performance of buildings in isolation from their urban context. Given the fact that much of the character of the traditional settlements of this region came from the collective visual perception of their architectural components as well as urban patterns. This paper presents a methodology that can be used to assess daylight behaviour at an architectural level as well as at an urban scale. The work examines the daylight behaviour of a well-known historic alleyway and of a courtyard house in the old city of Cairo. The variability in the visual perception and comfort for a typical pedestrian street and the occupants of the house was predicted using Radiance IES simulation modelling tool and a scaled model under an artificial sky dome. A comparative analysis between simulated results and measured values at target points was conducted and the results reveal a reasonable agreement with the simulation results. Preliminary results from the first phase of modelling were presented that give an insight into the overall visual experience in the traditional settlements in the Old City of Cairo where daylight has contributed to the place unique sense of identity.

Study on the visual performance of a traditional residential neighborhood in Old Cairo

Traditional dwellings located in the hot arid zone in Egypt are well known for their sensitive architectural response to the region's climatic conditions and socio-cultural norms. The majority of these dwellings are well recognized for their courtyard arrangement and perforated fenestration systems that evolved to control the harsh solar, climatic conditions without compromising the aesthetic quality of the space and the occupants' well-being. The unique visual characteristics of these structures cannot be fully appreciated by assessing the visual performance of buildings in isolation from their urban context. Much of the character of the traditional urban fabric of this region came from the collective visual perception of its architectural components as well as urban patterns. This paper examines daylight behavior of a well-known historic alleyway and of a courtyard house in the Old City of Cairo. Using the Radiance IES simulation modeling tool and a scaled model under an artificial sky dome, the paper investigates the visual comfort in a typical pedestrian street and a selected house. A comparative analysis between simulated results and measured values at target points was conducted. The results indicate a reasonable agreement with the simulation results. The paper gives an insight into the overall visual experience in the traditional settlements in the Old City of Cairo in relation to daylight components and hence their contribution to the unique sense of identity of the place.

Reproduction

"Reproduction" is a mixed reality installation that investigates the flow of data between the material world and synthetic worlds, in particular realtime 3D environments, through the creation of a persistent realtime 3D environment populated with agent entities that evolve over the duration of the exhibition in response to the actions of the human visitors to the 10 metre dome.

In vitro strain measurements in cerebral aneurysm models for cyber-physical diagnosis

Background: The development of new diagnostic technologies for cerebrovascular diseases requires an understanding of the mechanism behind the growth and rupture of cerebral aneurysms. To provide a comprehensive diagnosis and prognosis of this disease, it is desirable to evaluate wall shear stress, pressure, deformation and strain in the aneurysm region, based on information provided by medical imaging technologies. Methods: In this research, we propose a new cyber-physical system composed of in vitro dynamic strain experimental measurements and computational fluid dynamics (CFD) simulation for the diagnosis of cerebral aneurysms. A CFD simulation and a scaled-up membranous silicone model of a cerebral aneurysm were completed, based on patient-specific data recorded in August 2008. In vitro blood flow simulation was realized with the use of a specialized pump. A vision system was also developed to measure the strain at different regions on the model by way of pulsating blood flow circulating inside the model. Results: Experimental results show that distance and area strain maxima were larger near the aneurysm neck (0.042 and 0.052), followed by the aneurysm dome (0.023 and 0.04) and finally the main blood vessel section (0.01 and 0.014). These results were complemented by a CFD simulation for the addition of wall shear stress, oscillatory shear index and aneurysm formation index. Diagnosis results using imaging obtained in August 2008 are consistent with the monitored aneurysm growth in 2011. Conclusion: The presented study demonstrates a new experimental platform for measuring dynamic strain within cerebral aneurysms. This platform is also complemented by a CFD simulation for advanced diagnosis and prediction of the growth tendency of an aneurysm in endovascular surgery.

Cryo-rolling and formability of 2024 aluminium

Sheets of precipitate hardenable 2024 aluminium have been processed by rolling at liquid nitrogen temperature in order to refine the microstructure. A number of different aging/heat treating procedures have been utilised that have resulted in significantly different mechanical properties. The cryo-rolled material was heat treated at 150 °C for varying times and the resulting mechanical properties evaluated as a function of this holding time. The resulting properties were found to be strongly influenced by precipitates that formed either during the aging step, rolling process or the subsequent heat treatment. The formability of the cryo-rolled and heat treated material has been investigated using a limiting dome height test (Erichsen cupping test).

Seascape

Original artwork : finalist, ANL maritime art prize and exhibition at Dome Gallery, Mission to Seafarers, 2013