The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Carl T.f. Ross - One of the best experts on this subject based on the ideXlab platform.
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Vibration of a thin-walled shell under External Water pressure using ANSYS
Pressure Vessels, 2020Co-Authors: Carl T.f. RossAbstract:Theoretical and experimental investigations carried out on a thin-walled hemi-ellipsoidal prolate dome in air and also under External Water pressure are reported. There was good correlation between the experimental and theoretical results. The theoretical investigation was carried out using finite element analysis to model both the structure and the fluid. Two computer programs were used, one of which was the commercial computer program ANSYS and the other was an in-house computer program. For the shell structure, the ANSYS computer program used two different doubly curved thin-walled shell elements, whereas the in-house computer program used a simpler axisymmetric thin-walled shell element. The ANSYS program had the advantage over the in-house program in that it produced excellent graphical displays of the eigenmodes.
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Nonlinear vibration of a hemispherical dome under External Water pressure
Journal of Physics: Conference Series, 2011Co-Authors: Carl T.f. Ross, A Mclennan, A P F LittleAbstract:The aim of this study was to analyse the behaviour of a hemi-spherical dome when vibrated under External Water pressure, using the commercial computer package ANSYS 11.0. In order to achieve this aim, the dome was modelled and vibrated in air and then in Water, before finally being vibrated under External Water pressure. The results collected during each of the analyses were compared to the previous studies, and this demonstrated that ANSYS was a suitable program and produced accurate results for this type of analysis, together with excellent graphical displays. The analysis under External Water pressure, clearly demonstrated that as External Water pressure was increased, the resonant frequencies decreased and a type of dynamic buckling became likely; because the static buckling eigenmode was similar to the vibration eigenmode. ANSYS compared favourably with the in-house software, but had the advantage that it produced graphical displays. This also led to the identification of previously undetected meridional modes of vibration; which were not detected with the in-house software.
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Vibration of a thin-walled prolate dome under External Water pressure
Ocean Engineering, 2007Co-Authors: Carl T.f. Ross, A P F Little, Philipp Köster, Giles TewkesburyAbstract:The paper reports on a theoretical and an experimental investigation carried out on a thin-walled hemi-ellipsoidal prolate dome in air and also under External Water pressure. The investigation found that there was good correlation between experiment and theory. The theoretical investigation was carried out using the finite element analysis to model both the structure and the fluid. The theoretical investigation used two different programs, one of which was the giant computer program ANSYS and the other was an in-house program developed by Ross. For the shell structure, the ANSYS program used 2 different doubly curved thin-walled shell elements, while the in-house program used a simpler axisymmetric thin-walled shell element. This axisymmetric element allowed a sinusoidal variation of the displacements in the circumferential direction, thus, decreasing preparation and computational time. Agreement between the 3 different finite elements was found to be good. This was found particularly encouraging for the in-house software, as it only took a few hours to set up the computer model, and a few seconds to analyse the vessel, whereas the ANSYS software took several weeks to set up the computer model, and several minutes to analyse the shell dome. The ANSYS software, however, did have the advantage in producing excellent graphical displays in both the pre-processing and post-processing modes.
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Vibration of a thin-walled carbon fibre corrugated circular cylinder under External Water pressure
Thin-walled Structures, 2006Co-Authors: Carl T.f. Ross, A P F Little, Philipp Köster, Giles TewkesburyAbstract:Abstract The paper reports on a theoretical and an experimental investigation carried out on a thin-walled corrugated carbon fibre circular cylinder in air and also under External Water pressure. This corrugated circular cylinder was invented by Ross in 1987. The theoretical investigation was carried out using the finite element analysis to model both the structure and the fluid. The theoretical investigation used two different programs, one of which was the giant computer program ANSYS and the other was an in-house program developed by Ross and Little. For the shell structure, the ANSYS program used two different doubly curved thin-walled shell elements, while the in-house program used a simpler axisymmetric thin-walled shell element. This axisymmetric element allowed a sinusoidal variation of the displacements in the circumferential direction, thus, decreasing preparation and computational time. Agreement between the different finite elements was found to be quite good. The investigation also found that there was good correlation between experiment and theory for the in-house software, but was a little disappointing when using ANSYS. Errors may, however, have occurred with the experimental results, as the model was hand-made and neither its geometry nor its material properties were perfect. It was found particularly encouraging for the in-house software to give better results than ANSYS, as the in-house software only took a few hours to set up the computer model, and a few seconds to analyse the vessel, whereas the ANSYS software took several weeks to set up the computer model, and several minutes to analyse the shell. The ANSYS software, however, did have the advantage in producing excellent graphical displays in both the pre-processing and post-processing modes.
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The vibration of a large ring-stiffened prolate dome under External Water pressure
Ocean Engineering, 2003Co-Authors: Carl T.f. Ross, A P F Little, Colin BartlettAbstract:The paper presents a theoretical and an experimental investigation into the free vibration of a large ring-stiffened prolate dome in air and under External Water pressure. The theoretical investigation was via the finite element method where a solid fluid mesh with an isoparametric cross-section was used to model the Water surrounding the dome, and a truncated conical shell and ring stiffener were used to model the structure. Good agreement was found between theory and experiment. Both the theory and the experiment found that as the External Water pressure was increased the resonant frequencies decreased. # 2003 Elsevier Ltd. All rights reserved.
A P F Little - One of the best experts on this subject based on the ideXlab platform.
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Nonlinear vibration of a hemispherical dome under External Water pressure
Journal of Physics: Conference Series, 2011Co-Authors: Carl T.f. Ross, A Mclennan, A P F LittleAbstract:The aim of this study was to analyse the behaviour of a hemi-spherical dome when vibrated under External Water pressure, using the commercial computer package ANSYS 11.0. In order to achieve this aim, the dome was modelled and vibrated in air and then in Water, before finally being vibrated under External Water pressure. The results collected during each of the analyses were compared to the previous studies, and this demonstrated that ANSYS was a suitable program and produced accurate results for this type of analysis, together with excellent graphical displays. The analysis under External Water pressure, clearly demonstrated that as External Water pressure was increased, the resonant frequencies decreased and a type of dynamic buckling became likely; because the static buckling eigenmode was similar to the vibration eigenmode. ANSYS compared favourably with the in-house software, but had the advantage that it produced graphical displays. This also led to the identification of previously undetected meridional modes of vibration; which were not detected with the in-house software.
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Vibration of a thin-walled prolate dome under External Water pressure
Ocean Engineering, 2007Co-Authors: Carl T.f. Ross, A P F Little, Philipp Köster, Giles TewkesburyAbstract:The paper reports on a theoretical and an experimental investigation carried out on a thin-walled hemi-ellipsoidal prolate dome in air and also under External Water pressure. The investigation found that there was good correlation between experiment and theory. The theoretical investigation was carried out using the finite element analysis to model both the structure and the fluid. The theoretical investigation used two different programs, one of which was the giant computer program ANSYS and the other was an in-house program developed by Ross. For the shell structure, the ANSYS program used 2 different doubly curved thin-walled shell elements, while the in-house program used a simpler axisymmetric thin-walled shell element. This axisymmetric element allowed a sinusoidal variation of the displacements in the circumferential direction, thus, decreasing preparation and computational time. Agreement between the 3 different finite elements was found to be good. This was found particularly encouraging for the in-house software, as it only took a few hours to set up the computer model, and a few seconds to analyse the vessel, whereas the ANSYS software took several weeks to set up the computer model, and several minutes to analyse the shell dome. The ANSYS software, however, did have the advantage in producing excellent graphical displays in both the pre-processing and post-processing modes.
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Vibration of a thin-walled carbon fibre corrugated circular cylinder under External Water pressure
Thin-walled Structures, 2006Co-Authors: Carl T.f. Ross, A P F Little, Philipp Köster, Giles TewkesburyAbstract:Abstract The paper reports on a theoretical and an experimental investigation carried out on a thin-walled corrugated carbon fibre circular cylinder in air and also under External Water pressure. This corrugated circular cylinder was invented by Ross in 1987. The theoretical investigation was carried out using the finite element analysis to model both the structure and the fluid. The theoretical investigation used two different programs, one of which was the giant computer program ANSYS and the other was an in-house program developed by Ross and Little. For the shell structure, the ANSYS program used two different doubly curved thin-walled shell elements, while the in-house program used a simpler axisymmetric thin-walled shell element. This axisymmetric element allowed a sinusoidal variation of the displacements in the circumferential direction, thus, decreasing preparation and computational time. Agreement between the different finite elements was found to be quite good. The investigation also found that there was good correlation between experiment and theory for the in-house software, but was a little disappointing when using ANSYS. Errors may, however, have occurred with the experimental results, as the model was hand-made and neither its geometry nor its material properties were perfect. It was found particularly encouraging for the in-house software to give better results than ANSYS, as the in-house software only took a few hours to set up the computer model, and a few seconds to analyse the vessel, whereas the ANSYS software took several weeks to set up the computer model, and several minutes to analyse the shell. The ANSYS software, however, did have the advantage in producing excellent graphical displays in both the pre-processing and post-processing modes.
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The vibration of a large ring-stiffened prolate dome under External Water pressure
Ocean Engineering, 2003Co-Authors: Carl T.f. Ross, A P F Little, Colin BartlettAbstract:The paper presents a theoretical and an experimental investigation into the free vibration of a large ring-stiffened prolate dome in air and under External Water pressure. The theoretical investigation was via the finite element method where a solid fluid mesh with an isoparametric cross-section was used to model the Water surrounding the dome, and a truncated conical shell and ring stiffener were used to model the structure. Good agreement was found between theory and experiment. Both the theory and the experiment found that as the External Water pressure was increased the resonant frequencies decreased. # 2003 Elsevier Ltd. All rights reserved.
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The vibration of ring-stiffened prolate domes under External Water pressure
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2003Co-Authors: Carl T.f. Ross, A P F Little, L Chasapides, Ja Banks, D AttanasioAbstract:AbstractThe paper presents a theoretical and an experimental investigation into the free vibration of three ring-stiffened prolate domes in air and under External Water pressure. The theoretical investigation was via the finite element method where a solid fluid mesh was used to model the Water surrounding each dome. Good agreement was found between theory and experiment. Both the theory and the experiment found that, as the External Water pressure was increased, the resonant frequencies decreased.
Gunther Wennemuth - One of the best experts on this subject based on the ideXlab platform.
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The cellular mechanism for Water detection in the mammalian taste system
Nature Neuroscience, 2017Co-Authors: Dhruv Zocchi, Gunther WennemuthAbstract:Initiation of drinking behavior relies on both internal state and peripheral Water detection. While central neural circuits regulating thirst have been well studied, it is still unclear how mammals recognize External Water. Here we show that acid-sensing taste receptor cells (TRCs) that were previously suggested as the sour taste sensors also mediate taste responses to Water. Genetic silencing of these TRCs abolished Water-evoked responses in taste nerves. Optogenetic self-stimulation of acid-sensing TRCs in thirsty animals induced robust drinking responses toward light even without Water. This behavior was only observed when animals were Water-deprived but not under food- or salt-depleted conditions, indicating that the hedonic value of Water-evoked responses is highly internal-state dependent. Conversely, thirsty animals lacking functional acid-sensing TRCs showed compromised discrimination between Water and nonaqueous fluids. Taken together, this study revealed a function of mammalian acid-sensing TRCs that provide a cue for External Water. The authors find that mammalian acid-sensing taste receptor cells, previously shown to be putative sour taste sensors, also mediate responses to Water. Optogenetic activation of this population of cells in thirsty mice induced robust drinking response in the absence of Water. This study shows that acid-sensing TRCs contribute to the detection of Water in the oral cavity.
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The cellular mechanism for Water detection in the mammalian taste system
Nature Neuroscience, 2017Co-Authors: Dhruv Zocchi, Gunther WennemuthAbstract:Initiation of drinking behavior relies on both internal state and peripheral Water detection. While central neural circuits regulating thirst have been well studied, it is still unclear how mammals recognize External Water. Here we show that acid-sensing taste receptor cells (TRCs) that were previously suggested as the sour taste sensors also mediate taste responses to Water. Genetic silencing of these TRCs abolished Water-evoked responses in taste nerves. Optogenetic self-stimulation of acid-sensing TRCs in thirsty animals induced robust drinking responses toward light even without Water. This behavior was only observed when animals were Water-deprived but not under food- or salt-depleted conditions, indicating that the hedonic value of Water-evoked responses is highly internal-state dependent. Conversely, thirsty animals lacking functional acid-sensing TRCs showed compromised discrimination between Water and nonaqueous fluids. Taken together, this study revealed a function of mammalian acid-sensing TRCs that provide a cue for External Water.
Arjen Ysbert Hoekstra - One of the best experts on this subject based on the ideXlab platform.
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The External Water footprint of the Netherlands: Quantification and impact assessment
2017Co-Authors: Mesfin Mekonnen, Arjen Ysbert HoekstraAbstract:This study quantifies the External Water footprint of the Netherlands by partner country and import product and assesses the impact of this footprint by contrasting the geographically explicit Water footprint with Water scarcity in the different parts of the world. Hotspots are identified as the places where the External Water footprint of Dutch consumers is significant on the one hand and where Water scarcity is serious on the other hand. The study shows that Dutch consumption implies the use of Water resources throughout the world, with significant impacts at specified locations. This knowledge is relevant for consumers, government and businesses when addressing the sustainability of consumer behaviour and supply chains. The results of this study can be an input to bilateral cooperation between the Netherlands and the Dutch trade partners aimed at the reduction of the negative impacts of Dutch consumption on foreign Water resources. Dutch government can also engage with businesses in order to stimulate them to review the sustainability of their supply chains.
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the External Water footprint of the netherlands geographically explicit quantification and impact assessment
Ecological Economics, 2009Co-Authors: Mesfin Mekonnen, Arjen Ysbert HoekstraAbstract:This study quantifies the External Water footprint of the Netherlands by partner country and import product and assesses the impact of this footprint by contrasting the geographically-explicit Water footprint with Water scarcity in the different parts of the world. The total Water footprint of the Netherlands is estimated to be about 2300 m3/year/cap, of which 67% relates to the consumption of agricultural goods, 31% to the consumption of industrial goods, and 2% to domestic Water use. The Dutch Water footprint related to the consumption of agricultural goods, is composed as follows: 46% related to livestock products; 17% oil crops and oil from oil crops; 12% coffee, tea, cocoa and tobacco; 8% cereals and beer; 6% cotton products; 5% fruits; and 6% other agricultural products. About 11% of the Water footprint of the Netherlands is internal and 89% is External. Only 44% of virtual-Water import relates to products consumed in the Netherlands, thus constituting the External Water footprint. For agricultural products this is 40% and for industrial products this is 60%. The remaining 56% of the virtual-Water import to the Netherlands is re-exported. The impact of the External Water footprint of Dutch consumers is highest in countries that experience serious Water scarcity. Based on indicators for Water scarcity the following eight countries have been identified as most seriously affected: China; India; Spain; Turkey; Pakistan; Sudan; South Africa; and Mexico. This study shows that Dutch consumption implies the use of Water resources throughout the world, with significant impacts in Water-scarce regions.
Anna Werner - One of the best experts on this subject based on the ideXlab platform.
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Simulations of coatings to avoid External condensation on low U-value windows
Optical Materials, 2008Co-Authors: Anna Werner, Arne RoosAbstract:Simulation of different coatings to avoid External Water condensation on low U-value windows
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External Water Condensation and Angular Solar Absorptance : Theoretical Analysis and Practical Experience of Modern Windows
2007Co-Authors: Anna WernerAbstract:Part I of this thesis is a theoretical background to parts II and III. Part II treats the phenomenon of decreased visibility through a glazing due to External Water condensation, dew, on the extern ...
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Measurements of External Water Condensation on Simulated low U-value Windows with Different Coatings
Solar Energy, 2007Co-Authors: Anna Werner, Arne RoosAbstract:Part I of this thesis is a theoretical background to parts II and III. Part II treats the phenomenon of decreased visibility through a glazing due to External Water condensation, dew, on the External surface. Some simulations are presented where it is shown that under certain circumstances condensation can be expected. A combination of coatings on the External surface is suggested to overcome the problem of External condesation. It consists of both a coating which decreases the emissivity of the surface and a hydrophilic coating which reduces the detrimental effects to the view through the window. Fresnel calculations of the optical properties are used to discuss the feasibility of using different coatings. A new test box was used to verify that the proposed window coatings perform as expected. Part III is a study on the angular dependence of solar absorptance in windows. Optical properties vary with the angle of incidence of the incoming light. The variation is different from one window pane to another. A model is proposed to approximate the angular variation of the solar absorptance in window panes. The model is semi-empirical and involves dividing the wide range of windows into nine groups. To which group a window belongs, depends on how many panes it has and on the features of the outer pane. The strength of the model is that it can be used without knowing the exact optical properties of each pane of the window. This makes it useful in the many cases when these data are not given by the manufacturer and Fresnel calculations to get the optical properties of the window are not feasible. The model is simple and can be added as an appendix to existing standards for measuring optical properties of windows.
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Influence of climate and window parameters on the occurrence of External Water condensation on Swedish windows
Energy and Buildings, 2007Co-Authors: Anna Werner, Arne RoosAbstract:Part I of this thesis is a theoretical background to parts II and III. Part II treats the phenomenon of decreased visibility through a glazing due to External Water condensation, dew, on the External surface. Some simulations are presented where it is shown that under certain circumstances condensation can be expected. A combination of coatings on the External surface is suggested to overcome the problem of External condesation. It consists of both a coating which decreases the emissivity of the surface and a hydrophilic coating which reduces the detrimental effects to the view through the window. Fresnel calculations of the optical properties are used to discuss the feasibility of using different coatings. A new test box was used to verify that the proposed window coatings perform as expected. Part III is a study on the angular dependence of solar absorptance in windows. Optical properties vary with the angle of incidence of the incoming light. The variation is different from one window pane to another. A model is proposed to approximate the angular variation of the solar absorptance in window panes. The model is semi-empirical and involves dividing the wide range of windows into nine groups. To which group a window belongs, depends on how many panes it has and on the features of the outer pane. The strength of the model is that it can be used without knowing the exact optical properties of each pane of the window. This makes it useful in the many cases when these data are not given by the manufacturer and Fresnel calculations to get the optical properties of the window are not feasible. The model is simple and can be added as an appendix to existing standards for measuring optical properties of windows.
