After conducting a critical survey of the different categories of existing heat exchangers,the results of several experiments about the behaviour of a two-phase current in an open channel are reported.The results conf...After conducting a critical survey of the different categories of existing heat exchangers,the results of several experiments about the behaviour of a two-phase current in an open channel are reported.The results confirm the complexity of the problems induced in heat exchangers by flow maldistribution,especially when two-phase flows are considered in multi-channel systems.It is shown that severe misalignment of heat exchangers can lead to a loss of economic performance of more than 25%.Improper distribution of fluid flow causes longer fluid coils to form,and the liquid cochlea can eventually occupy a large space,thereby reducing heat transfer and disrupting the considered biphasic system.The use of a small diameter distribution pipe with properly spaced outlet holes seems to be a promising approach to fix many of these issues.It is found that the current distribution in the channels,in addition to the header pressure distribution,also depends on factors such as the geometry and the initial flow regime in the header.展开更多
Understanding the relation between spatial heterogeneity and structural rejuvenation is one of the hottest topics in the field of metallic glasses(MGs).In this work,molecular dynamics(MD)simulation is implemented to d...Understanding the relation between spatial heterogeneity and structural rejuvenation is one of the hottest topics in the field of metallic glasses(MGs).In this work,molecular dynamics(MD)simulation is implemented to discover the effects of initial spatial heterogeneity on the level of rejuvenation in the Ni_(80)P_(20)MGs.For this purpose,the samples are prepared with cooling rates of 10^(10) K/s-10^(12) K/s to make glassy alloys with different atomic configurations.Firstly,it is found that the increase in the cooling rate leads the Gaussian-type shear modulus distribution to widen,indicating the aggregations in both elastically soft and hard regions.After the primary evaluations,the elastostatic loading is also used to transform structural rejuvenation into the atomic configurations.The results indicate that the sample with intermediate structural heterogeneity prepared with 10^(11) K/s exhibits the maximum structural rejuvenation which is due to the fact that the atomic configuration in an intermediate structure contains more potential sites for generating the maximum atomic rearrangement and loosely packed regions under an external excitation.The features of atomic rearrangement and structural changes under the rejuvenation process are discussed in detail.展开更多
Sedimentary successions in the northwestern Gulf of Suez provide important clues to the understanding of the geological evolution of NE Africa during the middle and late Eocene.This study focuses on detailed facies an...Sedimentary successions in the northwestern Gulf of Suez provide important clues to the understanding of the geological evolution of NE Africa during the middle and late Eocene.This study focuses on detailed facies analyses in order to characterize the depositional environments and system tracts of the Bartonian-Priabonian succession cropping out in this area.Bartonian-Priabonian carbonate deposits in five stratigraphic sections constitute,from base to top,the Gebel Hof,Observatory,Sannur,Qurn,and Wadi Hof Formations.These formations contain four local assemblage zones of larger benthic foraminifers.Analyses of litho-,bio-,and microfacies in the succession resulted in the recognition of 12 lithofacies types.These lithofacies are represented by packages of lime-mudstones,wackestones,packstones,pack-to grainstones,grainstones,rudstones,boundstones and dolomites.These lithofacies have been grouped into four geneticallyrelated facies associations that represent,respectively,tidal flats/shallow subtidal,restricted-shelf/lagoonal,shoal bar,and outer-shelf lagoon/reefal depositional environments in a downslope shallow-marine inner-ramp setting.The vertical transitions of these facies associations,representing facies changes through time,imply fluctuations of the regional sea level.The two peaks in the Bartonian correspond to well-known global eustatic sea-level rises;the pronounced Priabonian regression must be ascribed to the known global eustatic sea-level fall in combination with regional tectonic activity.The facies distribution suggests that the study area was located in the direct vicinity of some islands during the Bartonian-Priabonian.展开更多
文摘After conducting a critical survey of the different categories of existing heat exchangers,the results of several experiments about the behaviour of a two-phase current in an open channel are reported.The results confirm the complexity of the problems induced in heat exchangers by flow maldistribution,especially when two-phase flows are considered in multi-channel systems.It is shown that severe misalignment of heat exchangers can lead to a loss of economic performance of more than 25%.Improper distribution of fluid flow causes longer fluid coils to form,and the liquid cochlea can eventually occupy a large space,thereby reducing heat transfer and disrupting the considered biphasic system.The use of a small diameter distribution pipe with properly spaced outlet holes seems to be a promising approach to fix many of these issues.It is found that the current distribution in the channels,in addition to the header pressure distribution,also depends on factors such as the geometry and the initial flow regime in the header.
文摘Understanding the relation between spatial heterogeneity and structural rejuvenation is one of the hottest topics in the field of metallic glasses(MGs).In this work,molecular dynamics(MD)simulation is implemented to discover the effects of initial spatial heterogeneity on the level of rejuvenation in the Ni_(80)P_(20)MGs.For this purpose,the samples are prepared with cooling rates of 10^(10) K/s-10^(12) K/s to make glassy alloys with different atomic configurations.Firstly,it is found that the increase in the cooling rate leads the Gaussian-type shear modulus distribution to widen,indicating the aggregations in both elastically soft and hard regions.After the primary evaluations,the elastostatic loading is also used to transform structural rejuvenation into the atomic configurations.The results indicate that the sample with intermediate structural heterogeneity prepared with 10^(11) K/s exhibits the maximum structural rejuvenation which is due to the fact that the atomic configuration in an intermediate structure contains more potential sites for generating the maximum atomic rearrangement and loosely packed regions under an external excitation.The features of atomic rearrangement and structural changes under the rejuvenation process are discussed in detail.
文摘Sedimentary successions in the northwestern Gulf of Suez provide important clues to the understanding of the geological evolution of NE Africa during the middle and late Eocene.This study focuses on detailed facies analyses in order to characterize the depositional environments and system tracts of the Bartonian-Priabonian succession cropping out in this area.Bartonian-Priabonian carbonate deposits in five stratigraphic sections constitute,from base to top,the Gebel Hof,Observatory,Sannur,Qurn,and Wadi Hof Formations.These formations contain four local assemblage zones of larger benthic foraminifers.Analyses of litho-,bio-,and microfacies in the succession resulted in the recognition of 12 lithofacies types.These lithofacies are represented by packages of lime-mudstones,wackestones,packstones,pack-to grainstones,grainstones,rudstones,boundstones and dolomites.These lithofacies have been grouped into four geneticallyrelated facies associations that represent,respectively,tidal flats/shallow subtidal,restricted-shelf/lagoonal,shoal bar,and outer-shelf lagoon/reefal depositional environments in a downslope shallow-marine inner-ramp setting.The vertical transitions of these facies associations,representing facies changes through time,imply fluctuations of the regional sea level.The two peaks in the Bartonian correspond to well-known global eustatic sea-level rises;the pronounced Priabonian regression must be ascribed to the known global eustatic sea-level fall in combination with regional tectonic activity.The facies distribution suggests that the study area was located in the direct vicinity of some islands during the Bartonian-Priabonian.
