The Experts below are selected from a list of 1164 Experts worldwide ranked by ideXlab platform
Chuang Xu - One of the best experts on this subject based on the ideXlab platform.
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a Multilayer Approach and its application to model a local gravimetric quasi geoid model over the north sea qgnsea v1 0
Geoscientific Model Development, 2018Co-Authors: Yihao Wu, Bo Zhong, Chuang XuAbstract:Abstract. A Multilayer Approach is set up for local gravity field recovery within the framework of multi-resolution representation, where the gravity field is parameterized as the superposition of multiple layers of Poisson wavelets located at different depths beneath the Earth's surface. The layers are designed to recover gravity signals at different scales, where the shallow and deep layers mainly capture the short- and long-wavelength signals, respectively. The depths of these layers are linked to the locations of different anomaly sources beneath the Earth's surface, which are estimated by wavelet decomposition and power spectrum analysis. For testing the performance of this Approach, a gravimetric quasi-geoid model over the North Sea, QGNSea V1.0, is modeled and validated against independent control data. The results show that the Multilayer Approach fits the gravity data better than the traditional single-layer Approach, particularly in regions with topographical variation. An Akaike information criterion (AIC) test shows that the Multilayer model obtains a smaller AIC value and achieves a better balance between the goodness of fit of data and the simplicity of the model. Further, an evaluation using independent GPS/leveling data tests the ability of regional models computed from different Approaches towards realistic extrapolation, which shows that the accuracies of the QGNSea V1.0 derived from the Multilayer Approach are better by 0.4, 0.9, and 1.1 cm in the Netherlands, Belgium, and parts of Germany, respectively, than that using the single-layer Approach. Further validation with existing models shows that QGNSea V1.0 is superior with respect to performance and may be beneficial for studying ocean circulation between the North Sea and its neighboring waters.
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a Multilayer Approach and its application in modeling qgnsea v1 0 a local gravmetric quasi geoid model over the north sea
Geoscientific Model Development Discussions, 2018Co-Authors: Yihao Wu, Bo Zhong, Chuang XuAbstract:A Multilayer Approach is set up for local gravity field modeling based on the idea of multi-resolution representation merging heterogeneous gravity data. Different layers of Poisson wavelets' grids are formed to recover the signals at various levels, where the shallow and deep layers mainly capture the short- and long-wavelength signals, respectively. The depths of these layers beneath the topography are linked to the locations that the anomaly sources locate, estimated by the wavelet decomposition and power spectrum analysis. For testing the performance of this Approach, a gravimetric quasi-geoid over the North Sea in Europe called QGNSea V1.0 is computed and compared with other existing models. The results show that the Multilayer Approach outperforms the traditionally used single-layer one in high-frequency bands, and the former fit the gravity data better, especially in regions with a tendency toward topographical variation. The evaluation with GPS/leveling data show the accuracies of QGNSea V1.0 modeled from the Multilayer Approach are improved by 0.3 cm, 0.6 cm and 0.8 cm in the Netherlands, Belgium and parts of Germany, respectively, compared to the original solution computed from the single-layer Approach. Further validation with existing models show QGNSea V1.0 has the best quality, which may be beneficial for studying the ocean circulation between the North Sea and neighbouring waters.
Yihao Wu - One of the best experts on this subject based on the ideXlab platform.
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a Multilayer Approach and its application to model a local gravimetric quasi geoid model over the north sea qgnsea v1 0
Geoscientific Model Development, 2018Co-Authors: Yihao Wu, Bo Zhong, Chuang XuAbstract:Abstract. A Multilayer Approach is set up for local gravity field recovery within the framework of multi-resolution representation, where the gravity field is parameterized as the superposition of multiple layers of Poisson wavelets located at different depths beneath the Earth's surface. The layers are designed to recover gravity signals at different scales, where the shallow and deep layers mainly capture the short- and long-wavelength signals, respectively. The depths of these layers are linked to the locations of different anomaly sources beneath the Earth's surface, which are estimated by wavelet decomposition and power spectrum analysis. For testing the performance of this Approach, a gravimetric quasi-geoid model over the North Sea, QGNSea V1.0, is modeled and validated against independent control data. The results show that the Multilayer Approach fits the gravity data better than the traditional single-layer Approach, particularly in regions with topographical variation. An Akaike information criterion (AIC) test shows that the Multilayer model obtains a smaller AIC value and achieves a better balance between the goodness of fit of data and the simplicity of the model. Further, an evaluation using independent GPS/leveling data tests the ability of regional models computed from different Approaches towards realistic extrapolation, which shows that the accuracies of the QGNSea V1.0 derived from the Multilayer Approach are better by 0.4, 0.9, and 1.1 cm in the Netherlands, Belgium, and parts of Germany, respectively, than that using the single-layer Approach. Further validation with existing models shows that QGNSea V1.0 is superior with respect to performance and may be beneficial for studying ocean circulation between the North Sea and its neighboring waters.
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a Multilayer Approach and its application in modeling qgnsea v1 0 a local gravmetric quasi geoid model over the north sea
Geoscientific Model Development Discussions, 2018Co-Authors: Yihao Wu, Bo Zhong, Chuang XuAbstract:A Multilayer Approach is set up for local gravity field modeling based on the idea of multi-resolution representation merging heterogeneous gravity data. Different layers of Poisson wavelets' grids are formed to recover the signals at various levels, where the shallow and deep layers mainly capture the short- and long-wavelength signals, respectively. The depths of these layers beneath the topography are linked to the locations that the anomaly sources locate, estimated by the wavelet decomposition and power spectrum analysis. For testing the performance of this Approach, a gravimetric quasi-geoid over the North Sea in Europe called QGNSea V1.0 is computed and compared with other existing models. The results show that the Multilayer Approach outperforms the traditionally used single-layer one in high-frequency bands, and the former fit the gravity data better, especially in regions with a tendency toward topographical variation. The evaluation with GPS/leveling data show the accuracies of QGNSea V1.0 modeled from the Multilayer Approach are improved by 0.3 cm, 0.6 cm and 0.8 cm in the Netherlands, Belgium and parts of Germany, respectively, compared to the original solution computed from the single-layer Approach. Further validation with existing models show QGNSea V1.0 has the best quality, which may be beneficial for studying the ocean circulation between the North Sea and neighbouring waters.
Luis Velasco - One of the best experts on this subject based on the ideXlab platform.
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Comparing single layer and Multilayer Approaches to serve multicast requests on flexgrid networks
2015 17th International Conference on Transparent Optical Networks (ICTON), 2015Co-Authors: Lluís Gifre, Marc Ruiz, Adrià Asensio, Luis VelascoAbstract:Advanced services require high bitrate multicast connectivity being provided by core transport networks. Multicast services can be supported by a tree connecting the source to every destination of the multicast request. As a result of the bitrate that might be required, providing them directly on the optical layer could bring benefits. Notwithstanding, with the advent of the flexgrid technology, connections with capacities of 400 Gb/s and beyond can be set up that opens opportunities to create virtual topologies on which multicast services can be provided. In this paper, we compare the performance of providing high bitrate multicast services on the single layer and the Multilayer Approach; heuristic algorithms for the two considered Approaches are developed. Exhaustive simulation results carried out on three national core network topologies show that the tree scheme on the Multilayer Approach outperforms the rest of options.
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Serving Multicast Requests on Single-Layer and Multilayer Flexgrid Networks
Journal of Optical Communications and Networking, 2015Co-Authors: Marc Ruiz, Luis VelascoAbstract:Advanced services require a high bitrate, e.g., multigigabit, multicast connectivity being provided by core transport networks. Multicast services can be supported either by one single tree connecting the source to every destination of the multicast request or by a set of paths. The tree scheme could reduce resource utilization, and as a result of the bitrate that might be required, providing them directly on the optical layer could bring benefits. Apart from those benefits, with the advent of flexgrid technology, connections with 100 and 400 Gbits/s and beyond can be set up, which opens up opportunities to create virtual topologies on which multicast services can be provided. The kind of transponders that are needed under the single-layer and Multilayer Approaches are slightly different. While bandwidth-variable optical transponders (BVTs) can be used in the Multilayer Approach, assuming that the virtual topology is supported on high-bitrate optical connections so as to facilitate the performance of grooming, using sliceable BVTs (SBVTs) in the single-layer Approach might help to share capacity in the transponders. In this paper, we compare the performance of high-bitrate multicast services using the path and the tree scheme on the single-layer and Multilayer Approaches. Mathematical programming models for the tree scheme on the two Approaches considered are developed to compute the routing for incoming multicast requests in dynamic scenarios. With the goal of reducing computation time, heuristic algorithms providing a much better trade-off between optimality and complexity are proposed. Exhaustive simulation results carried out on three national core network topologies show that the tree scheme on the Multilayer Approach outperforms the rest of the options.
John D Brennan - One of the best experts on this subject based on the ideXlab platform.
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rapid fabrication of core shell silica particles using a Multilayer by Multilayer Approach
Chemical Communications, 2011Co-Authors: Hanjiang Dong, John D BrennanAbstract:Monodisperse silica core–shell particles with a high surface area and large pore size were rapidly prepared via a Multilayer-by-Multilayer (ML-b-ML) process, with 6–7 layers of silica nanoparticles deposited per coating cycle onto an oppositely charged polyelectrolyte in 0.1 M NH4NO3 at pH 2.7. The resultant porous shells show much greater porosity compared to particles obtained by the traditional layer-by-layer process.
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Rapid fabrication of core–shell silica particles using a Multilayer-by-Multilayer Approach
Chemical Communications, 2010Co-Authors: Hanjiang Dong, John D BrennanAbstract:Monodisperse silica core–shell particles with a high surface area and large pore size were rapidly prepared via a Multilayer-by-Multilayer (ML-b-ML) process, with 6–7 layers of silica nanoparticles deposited per coating cycle onto an oppositely charged polyelectrolyte in 0.1 M NH4NO3 at pH 2.7. The resultant porous shells show much greater porosity compared to particles obtained by the traditional layer-by-layer process.
Marc Ruiz - One of the best experts on this subject based on the ideXlab platform.
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Comparing single layer and Multilayer Approaches to serve multicast requests on flexgrid networks
2015 17th International Conference on Transparent Optical Networks (ICTON), 2015Co-Authors: Lluís Gifre, Marc Ruiz, Adrià Asensio, Luis VelascoAbstract:Advanced services require high bitrate multicast connectivity being provided by core transport networks. Multicast services can be supported by a tree connecting the source to every destination of the multicast request. As a result of the bitrate that might be required, providing them directly on the optical layer could bring benefits. Notwithstanding, with the advent of the flexgrid technology, connections with capacities of 400 Gb/s and beyond can be set up that opens opportunities to create virtual topologies on which multicast services can be provided. In this paper, we compare the performance of providing high bitrate multicast services on the single layer and the Multilayer Approach; heuristic algorithms for the two considered Approaches are developed. Exhaustive simulation results carried out on three national core network topologies show that the tree scheme on the Multilayer Approach outperforms the rest of options.
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Serving Multicast Requests on Single-Layer and Multilayer Flexgrid Networks
Journal of Optical Communications and Networking, 2015Co-Authors: Marc Ruiz, Luis VelascoAbstract:Advanced services require a high bitrate, e.g., multigigabit, multicast connectivity being provided by core transport networks. Multicast services can be supported either by one single tree connecting the source to every destination of the multicast request or by a set of paths. The tree scheme could reduce resource utilization, and as a result of the bitrate that might be required, providing them directly on the optical layer could bring benefits. Apart from those benefits, with the advent of flexgrid technology, connections with 100 and 400 Gbits/s and beyond can be set up, which opens up opportunities to create virtual topologies on which multicast services can be provided. The kind of transponders that are needed under the single-layer and Multilayer Approaches are slightly different. While bandwidth-variable optical transponders (BVTs) can be used in the Multilayer Approach, assuming that the virtual topology is supported on high-bitrate optical connections so as to facilitate the performance of grooming, using sliceable BVTs (SBVTs) in the single-layer Approach might help to share capacity in the transponders. In this paper, we compare the performance of high-bitrate multicast services using the path and the tree scheme on the single-layer and Multilayer Approaches. Mathematical programming models for the tree scheme on the two Approaches considered are developed to compute the routing for incoming multicast requests in dynamic scenarios. With the goal of reducing computation time, heuristic algorithms providing a much better trade-off between optimality and complexity are proposed. Exhaustive simulation results carried out on three national core network topologies show that the tree scheme on the Multilayer Approach outperforms the rest of the options.