This paper presents an original probabilistic model of a hybrid underwater wireless sensor network(UWSN),which includes a network of stationary sensors placed on the seabed and a mobile gateway.The mobile gateway is a...This paper presents an original probabilistic model of a hybrid underwater wireless sensor network(UWSN),which includes a network of stationary sensors placed on the seabed and a mobile gateway.The mobile gateway is a wave glider that collects data from the underwater network segment and retransmits it to the processing center.The authors consider the joint problem of optimal localization of stationary network nodes and the corresponding model for bypassing reference nodes by a wave glider.The optimality of the network is evaluated according to the criteria of energy efficiency and reliability.The influence of various physical and technical parameters of the network on its energy efficiency and on the lifespan of sensor nodes is analyzed.The analysis is carried out for networks of various scales,depending on the localization of stationary nodes and the model of bypassing the network with a wave glider.As a model example,the simulation of the functional characteristics of the network for a given size of the water area is carried out.It is shown that in the case of a medium-sized water area,the model of“bypassing the perimeter”by a wave glider is practically feasible,energy efficient and reliable for hourly data measurements.In the case of a large water area,the cluster bypass model becomes more efficient.展开更多
Waxy crude oil is known for its high wax contents that can potentially result in gelling following sufficient cooling of the transportation line in the subsea bed at offshore fields.The gelling over the entire lines r...Waxy crude oil is known for its high wax contents that can potentially result in gelling following sufficient cooling of the transportation line in the subsea bed at offshore fields.The gelling over the entire lines requires an accurately predicted restart pressure to restart the clogged and idle system.However,the common way of predicting the restart pressure has been reported to result in over-designed and predicted piping parameters.Recent research findings evidenced the formation of voids which would reduce the restart pressure significantly.The study conducted in this paper is aimed at investigating the voids size distribution in gelled crude oil across and along transportation pipelines.Sets of experiments simulating crude oil transportation during both static and dynamic cooling were conducted.The gelled crude oil below the pour point temperature was then scanned using a Magnetic Resonance Imaging(MRI)system to detect the voids formed.The resulting voids at each scanning cross-section were quantified,and their distributions were investigated.It was observed that dynamic cooling had minimal impacts on the voids size difference along the pipeline with the difference in voids areas within 10 mm^(2) to be twice and uniform for the entire flow rates tested.However,voids size in statically cooled waxy crude oil was found to be highly distributed with a maximum of 6 voids size distribution in 10 mm2 ranges.The low-end temperature had the highest size difference while the difference was decreasing with higher end temperatures.This study shows that the voids amount in dynamically cooled waxy crude oil could also be estimated with lower numbers of cross-sectional voids areas.However,the higher cross-sectional voids detection is recommended while estimating voids in statically cooled waxy crude oil.展开更多
基金The research was partially funded by the Ministry of Science and Higher Education of the Russian Federation as part of World-class Research Center program:Advanced Digital Technologies(Contract No.075-15-2020-903 dated 16.11.2020).
文摘This paper presents an original probabilistic model of a hybrid underwater wireless sensor network(UWSN),which includes a network of stationary sensors placed on the seabed and a mobile gateway.The mobile gateway is a wave glider that collects data from the underwater network segment and retransmits it to the processing center.The authors consider the joint problem of optimal localization of stationary network nodes and the corresponding model for bypassing reference nodes by a wave glider.The optimality of the network is evaluated according to the criteria of energy efficiency and reliability.The influence of various physical and technical parameters of the network on its energy efficiency and on the lifespan of sensor nodes is analyzed.The analysis is carried out for networks of various scales,depending on the localization of stationary nodes and the model of bypassing the network with a wave glider.As a model example,the simulation of the functional characteristics of the network for a given size of the water area is carried out.It is shown that in the case of a medium-sized water area,the model of“bypassing the perimeter”by a wave glider is practically feasible,energy efficient and reliable for hourly data measurements.In the case of a large water area,the cluster bypass model becomes more efficient.
文摘Waxy crude oil is known for its high wax contents that can potentially result in gelling following sufficient cooling of the transportation line in the subsea bed at offshore fields.The gelling over the entire lines requires an accurately predicted restart pressure to restart the clogged and idle system.However,the common way of predicting the restart pressure has been reported to result in over-designed and predicted piping parameters.Recent research findings evidenced the formation of voids which would reduce the restart pressure significantly.The study conducted in this paper is aimed at investigating the voids size distribution in gelled crude oil across and along transportation pipelines.Sets of experiments simulating crude oil transportation during both static and dynamic cooling were conducted.The gelled crude oil below the pour point temperature was then scanned using a Magnetic Resonance Imaging(MRI)system to detect the voids formed.The resulting voids at each scanning cross-section were quantified,and their distributions were investigated.It was observed that dynamic cooling had minimal impacts on the voids size difference along the pipeline with the difference in voids areas within 10 mm^(2) to be twice and uniform for the entire flow rates tested.However,voids size in statically cooled waxy crude oil was found to be highly distributed with a maximum of 6 voids size distribution in 10 mm2 ranges.The low-end temperature had the highest size difference while the difference was decreasing with higher end temperatures.This study shows that the voids amount in dynamically cooled waxy crude oil could also be estimated with lower numbers of cross-sectional voids areas.However,the higher cross-sectional voids detection is recommended while estimating voids in statically cooled waxy crude oil.
