The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
Uwe R. Zimmer - One of the best experts on this subject based on the ideXlab platform.
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FSR - Tracking Environmental Isoclines Using Polygonal Formations of Submersible Autonomous Vehicles
Springer Tracts in Advanced Robotics, 2020Co-Authors: Shahab Kalantar, Uwe R. ZimmerAbstract:Knowledge of iso-contours of the underwater terrain can be used to reconstruct it using interpolation. Identifying a set of Isoclines can be more efficient and less time-intensive than sweeping a large area. In this paper, we propose a system where a small number of agile underwater vehicles cooperatively maintain a polygonal formation on a plane above the terrain and use field values measured by the individual robots to locally reconstruct the field using interpolation schemes. The formation then tracks a desired iso-contour of the field by tracking the corresponding curve on the reconstructed field.
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IROS - Scale-adaptive polygonal formations of submersible vehicles and tracking isocontours
2008 IEEE RSJ International Conference on Intelligent Robots and Systems, 2008Co-Authors: Shahab Kalantar, Uwe R. ZimmerAbstract:Building on the assumption that identification of a sufficient number of Isoclines of an environmental field (such as the ocean bottom terrain) allows efficient reconstruction of the field, in this paper, a sequel to [1], we describe a system where a group of robots in a spacial arrangement (a regular polygon centred around a lead robot) locally construct the field (measured at the locations of the robots) inside the polygonal area using interpolation by barycentric coordinates. If the error of interpolation is small enough, the corresponding isocline of the interpolated field will match the real isocline accurately enough. Tracking this isocline in a certain direction will then allow robust traversal of field Isoclines. We use the measurement at the centre of the formation to adjust the size of the polygon to obtain desired accuracy.
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Scale-adaptive polygonal formations of submersible vehicles and tracking isocontours
2008 IEEE RSJ International Conference on Intelligent Robots and Systems, 2008Co-Authors: Shahab Kalantar, Uwe R. ZimmerAbstract:Building on the assumption that identification of a sufficient number of Isoclines of an environmental field (such as the ocean bottom terrain) allows efficient reconstruction of the field, in this paper, a sequel to [1], we describe a system where a group of robots in a spacial arrangement (a regular polygon centred around a lead robot) locally construct the field (measured at the locations of the robots) inside the polygonal area using interpolation by barycentric coordinates. If the error of interpolation is small enough, the corresponding isocline of the interpolated field will match the real isocline accurately enough. Tracking this isocline in a certain direction will then allow robust traversal of field Isoclines. We use the measurement at the centre of the formation to adjust the size of the polygon to obtain desired accuracy.
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tracking environmental Isoclines using polygonal formations of submersible autonomous vehicles
Field and Service Robotics, 2008Co-Authors: Shahab Kalantar, Uwe R. ZimmerAbstract:Knowledge of iso-contours of the underwater terrain can be used to reconstruct it using interpolation. Identifying a set of Isoclines can be more efficient and less time-intensive than sweeping a large area. In this paper, we propose a system where a small number of agile underwater vehicles cooperatively maintain a polygonal formation on a plane above the terrain and use field values measured by the individual robots to locally reconstruct the field using interpolation schemes. The formation then tracks a desired iso-contour of the field by tracking the corresponding curve on the reconstructed field.
Shahab Kalantar - One of the best experts on this subject based on the ideXlab platform.
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FSR - Tracking Environmental Isoclines Using Polygonal Formations of Submersible Autonomous Vehicles
Springer Tracts in Advanced Robotics, 2020Co-Authors: Shahab Kalantar, Uwe R. ZimmerAbstract:Knowledge of iso-contours of the underwater terrain can be used to reconstruct it using interpolation. Identifying a set of Isoclines can be more efficient and less time-intensive than sweeping a large area. In this paper, we propose a system where a small number of agile underwater vehicles cooperatively maintain a polygonal formation on a plane above the terrain and use field values measured by the individual robots to locally reconstruct the field using interpolation schemes. The formation then tracks a desired iso-contour of the field by tracking the corresponding curve on the reconstructed field.
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IROS - Scale-adaptive polygonal formations of submersible vehicles and tracking isocontours
2008 IEEE RSJ International Conference on Intelligent Robots and Systems, 2008Co-Authors: Shahab Kalantar, Uwe R. ZimmerAbstract:Building on the assumption that identification of a sufficient number of Isoclines of an environmental field (such as the ocean bottom terrain) allows efficient reconstruction of the field, in this paper, a sequel to [1], we describe a system where a group of robots in a spacial arrangement (a regular polygon centred around a lead robot) locally construct the field (measured at the locations of the robots) inside the polygonal area using interpolation by barycentric coordinates. If the error of interpolation is small enough, the corresponding isocline of the interpolated field will match the real isocline accurately enough. Tracking this isocline in a certain direction will then allow robust traversal of field Isoclines. We use the measurement at the centre of the formation to adjust the size of the polygon to obtain desired accuracy.
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Scale-adaptive polygonal formations of submersible vehicles and tracking isocontours
2008 IEEE RSJ International Conference on Intelligent Robots and Systems, 2008Co-Authors: Shahab Kalantar, Uwe R. ZimmerAbstract:Building on the assumption that identification of a sufficient number of Isoclines of an environmental field (such as the ocean bottom terrain) allows efficient reconstruction of the field, in this paper, a sequel to [1], we describe a system where a group of robots in a spacial arrangement (a regular polygon centred around a lead robot) locally construct the field (measured at the locations of the robots) inside the polygonal area using interpolation by barycentric coordinates. If the error of interpolation is small enough, the corresponding isocline of the interpolated field will match the real isocline accurately enough. Tracking this isocline in a certain direction will then allow robust traversal of field Isoclines. We use the measurement at the centre of the formation to adjust the size of the polygon to obtain desired accuracy.
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tracking environmental Isoclines using polygonal formations of submersible autonomous vehicles
Field and Service Robotics, 2008Co-Authors: Shahab Kalantar, Uwe R. ZimmerAbstract:Knowledge of iso-contours of the underwater terrain can be used to reconstruct it using interpolation. Identifying a set of Isoclines can be more efficient and less time-intensive than sweeping a large area. In this paper, we propose a system where a small number of agile underwater vehicles cooperatively maintain a polygonal formation on a plane above the terrain and use field values measured by the individual robots to locally reconstruct the field using interpolation schemes. The formation then tracks a desired iso-contour of the field by tracking the corresponding curve on the reconstructed field.
Zvika Abramsky - One of the best experts on this subject based on the ideXlab platform.
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gerbils under threat of owl predation Isoclines and isodars
Oikos, 1997Co-Authors: Zvika Abramsky, Michael L. Rosenzweig, Aziz SubachAbstract:We trained barn owls to fly over 2-ha field enclosures containing populations of Gerhillus allenbyi. Each 2-ha plot was divided into two equal parts by a fence with gates allowing easy passage of the gerbils. We varied the number of gerbils in the enclosure and the number of owl flights on each side of the dividing fence. Gerbil foraging activity responded within two hours to the difference in number of owl flights over the subplots. The greater the difference, the more the gerbils shifted their foraging to the subplot with fewer flights. Gerbils did not reduce their total foraging effort but redistributed it between subplots. In the absence of owl flights, gerbils divided their foraging effort equally between the matched subplots. Thus, they appear to seek an ideal free distribution in the two halves of each plot. Therefore, based on the gerbils' distribution of activity in the presence of different numbers of owl flights over the two subplots we estimated the shapes and slopes of the gerbil victim Isoclines in the middle and right hand side of the 'gerbil-activity vs number of owl flights' state space. The Isoclines were parallel straight lines with slope equal to -0.57. We believe this to be the first estimate of a victim isocline for a population of vertebrates in the field. Using the isodar method of Morris, we also determined that the fitness cost of each additional gerbil, i.e., per capita intraspecific competition among the G. allenbyi, is constant. It does not depend on either owl flight frequencies or G. allenbyi densities. The isodar also shows that the fitness cost of added owl flights does not vary with G. allenbyi population densities.
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The Shape of a Gerbillus pyramidum (Rodentia: Gerbillinae) Isocline: An Experimental Field Study
Oikos, 1994Co-Authors: Zvika Abramsky, Ofer Ovadia, Michael L. RosenzweigAbstract:Abramsky et al. developed a new technique to measure Isoclines in the field. The method is based on the single-species habitat selection theory of Fretwell. Using short term (3-4 wk) and long term (1-yr) experiments, they tested it by measuring the isocline of Gerbillus allenbyi competing with G. pyramidum. In the present study, we measured the converse isocline of G. pyramidum competing with G. allenbyi. Like the isocline of G. allenbyi, the isocline of G. pyramidum is nonlinear and agrees with the predictions of the theory of optimal density-dependent habitat selection in a twospecies, shared-preference system. This is the first natural system in which both sets of isolegs and Isoclines have been measured, in the field, for two competing species. A stability analysis suggested that the gerbil species can coexist under most observed density combinations
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The shape of a gerbil isocline: an experimental field study
Oikos, 1992Co-Authors: Zvika Abramsky, Michael L. Rosenzweig, A. ZubachAbstract:Abramsky et al. developed a new technique to measure Isoclines in the field. The method is based on the single-species habitat selection theory of Fretwell. Using short term experiments (3-4 wk), they tested it by measuring the isocline of Gerbillus allenbyi competing with G. pyramidum is six 1-ha enclosures but allowed individuals of G. allenbyi to move between adjacent enclosures and the surrounding environment. The resulting isocline of the present study was very similar to that obtained during the short term study. The isocline was nonlinear and agreed with the unique predictions of the theory of optimal density-dependent habitat selection in two-species, shared-preference systems
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The Shape of a Gerbil Isocline Measured Using Principles of Optimal Habitat Selection
Ecology, 1991Co-Authors: Zvika Abramsky, Michael L. Rosenzweig, Berry PinshowAbstract:The Isoclines of Gerbillus allenbyi competing with G. pyramidum are negatively sloped and at least approximately parallel. They are not linear, however; they are steeper over both low and high G. pyramidum densities and only very slightly negative at intermediate densities. This nonlinearity agrees with the predictions of the theory of optimal density—dependent habitat selection in a two—species, shared—preference system, the system that obtains here. The isocline field was measured by a new method based on the single—species habitat selection theory of Fretwell. The species whose Isoclines are being measured (the target species) is given a chance to equilibrate its per capita reproductive rate across a fence that separates two densities of its competitors. Equilibration requires that the target species distribute its density unequally on the two side of the fence. The general features of the method may be useful in other animal studies where densities can be experimentally manipulated.
Bernhard O. Palsson - One of the best experts on this subject based on the ideXlab platform.
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Characterizing the metabolic phenotype: A phenotype phase plane analysis
Biotechnology and bioengineering, 2002Co-Authors: Jeremy S. Edwards, Ramprasad Ramakrishna, Bernhard O. PalssonAbstract:Genome-scale metabolic maps can be reconstructed from annotated genome sequence data, biochemical literature, bioinformatic analysis, and strain-specific information. Flux-balance analysis has been useful for qualitative and quantitative analysis of metabolic reconstructions. In the past, FBA has typically been performed in one growth condition at a time, thus giving a limited view of the metabolic capabilities of a metabolic network. We have broadened the use of FBA to map the optimal metabolic flux distribution onto a single plane, which is defined by the availability of two key substrates. A finite number of qualitatively distinct patterns of metabolic pathway utilization were identified in this plane, dividing it into discrete phases. The characteristics of these distinct phases are interpreted using ratios of shadow prices in the form of Isoclines. The Isoclines can be used to classify the state of the metabolic network. This methodology gives rise to a "phase plane" analysis of the metabolic genotype-phenotype relation relevant for a range of growth conditions. Phenotype phase planes (PhPPs) were generated for Escherichia coli growth on two carbon sources (acetate and glucose) at all levels of oxygenation, and the resulting optimal metabolic phenotypes were studied. Supplementary information can be downloaded from our website (http://epicurus.che.udel.edu).
Michael L. Rosenzweig - One of the best experts on this subject based on the ideXlab platform.
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gerbils under threat of owl predation Isoclines and isodars
Oikos, 1997Co-Authors: Zvika Abramsky, Michael L. Rosenzweig, Aziz SubachAbstract:We trained barn owls to fly over 2-ha field enclosures containing populations of Gerhillus allenbyi. Each 2-ha plot was divided into two equal parts by a fence with gates allowing easy passage of the gerbils. We varied the number of gerbils in the enclosure and the number of owl flights on each side of the dividing fence. Gerbil foraging activity responded within two hours to the difference in number of owl flights over the subplots. The greater the difference, the more the gerbils shifted their foraging to the subplot with fewer flights. Gerbils did not reduce their total foraging effort but redistributed it between subplots. In the absence of owl flights, gerbils divided their foraging effort equally between the matched subplots. Thus, they appear to seek an ideal free distribution in the two halves of each plot. Therefore, based on the gerbils' distribution of activity in the presence of different numbers of owl flights over the two subplots we estimated the shapes and slopes of the gerbil victim Isoclines in the middle and right hand side of the 'gerbil-activity vs number of owl flights' state space. The Isoclines were parallel straight lines with slope equal to -0.57. We believe this to be the first estimate of a victim isocline for a population of vertebrates in the field. Using the isodar method of Morris, we also determined that the fitness cost of each additional gerbil, i.e., per capita intraspecific competition among the G. allenbyi, is constant. It does not depend on either owl flight frequencies or G. allenbyi densities. The isodar also shows that the fitness cost of added owl flights does not vary with G. allenbyi population densities.
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The Shape of a Gerbillus pyramidum (Rodentia: Gerbillinae) Isocline: An Experimental Field Study
Oikos, 1994Co-Authors: Zvika Abramsky, Ofer Ovadia, Michael L. RosenzweigAbstract:Abramsky et al. developed a new technique to measure Isoclines in the field. The method is based on the single-species habitat selection theory of Fretwell. Using short term (3-4 wk) and long term (1-yr) experiments, they tested it by measuring the isocline of Gerbillus allenbyi competing with G. pyramidum. In the present study, we measured the converse isocline of G. pyramidum competing with G. allenbyi. Like the isocline of G. allenbyi, the isocline of G. pyramidum is nonlinear and agrees with the predictions of the theory of optimal density-dependent habitat selection in a twospecies, shared-preference system. This is the first natural system in which both sets of isolegs and Isoclines have been measured, in the field, for two competing species. A stability analysis suggested that the gerbil species can coexist under most observed density combinations
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The shape of a gerbil isocline: an experimental field study
Oikos, 1992Co-Authors: Zvika Abramsky, Michael L. Rosenzweig, A. ZubachAbstract:Abramsky et al. developed a new technique to measure Isoclines in the field. The method is based on the single-species habitat selection theory of Fretwell. Using short term experiments (3-4 wk), they tested it by measuring the isocline of Gerbillus allenbyi competing with G. pyramidum is six 1-ha enclosures but allowed individuals of G. allenbyi to move between adjacent enclosures and the surrounding environment. The resulting isocline of the present study was very similar to that obtained during the short term study. The isocline was nonlinear and agreed with the unique predictions of the theory of optimal density-dependent habitat selection in two-species, shared-preference systems
-
The Shape of a Gerbil Isocline Measured Using Principles of Optimal Habitat Selection
Ecology, 1991Co-Authors: Zvika Abramsky, Michael L. Rosenzweig, Berry PinshowAbstract:The Isoclines of Gerbillus allenbyi competing with G. pyramidum are negatively sloped and at least approximately parallel. They are not linear, however; they are steeper over both low and high G. pyramidum densities and only very slightly negative at intermediate densities. This nonlinearity agrees with the predictions of the theory of optimal density—dependent habitat selection in a two—species, shared—preference system, the system that obtains here. The isocline field was measured by a new method based on the single—species habitat selection theory of Fretwell. The species whose Isoclines are being measured (the target species) is given a chance to equilibrate its per capita reproductive rate across a fence that separates two densities of its competitors. Equilibration requires that the target species distribute its density unequally on the two side of the fence. The general features of the method may be useful in other animal studies where densities can be experimentally manipulated.
