The development of stationary patterns on a thin polymer surface subject to an electric field is studied by means of the hexagonal-planform weakly nonlinear stability analysis and numerical simulations. The time evolu...The development of stationary patterns on a thin polymer surface subject to an electric field is studied by means of the hexagonal-planform weakly nonlinear stability analysis and numerical simulations. The time evolution of the interface between the air and the polymer film on the unbounded spatial domain is described by a thin film equation, incorporating the electric driving force and the surface diffusion.The nonlinear interfacial growth includes the amplitude equations and superposition of one-dimensional structures at regular orientations. The pattern selection is driven by the subcritical instability mechanism in which the relative thickness of the polymer film plays a critical role.展开更多
This note is an addendum to the results of Lazer and Frederickson [1], and Lazer [4] on periodic oscillations, with linear part at resonance. We show that a small modification of the argument in [4] provides a more ge...This note is an addendum to the results of Lazer and Frederickson [1], and Lazer [4] on periodic oscillations, with linear part at resonance. We show that a small modification of the argument in [4] provides a more general result. It turns out that things are different for the correspouding Dirichlet boundary value problem.展开更多
We present iterative numerical methods for solving the inverse problem of recovering the nonnegative Robin coefficient from partial boundary measurement of the solution to the Laplace equation. Based on the boundary i...We present iterative numerical methods for solving the inverse problem of recovering the nonnegative Robin coefficient from partial boundary measurement of the solution to the Laplace equation. Based on the boundary integral equation formulation of the problem, nonnegativity constraints in the form of a penalty term are incorporated conveniently into least-squares iteration schemes for solving the inverse problem. Numerical implementation and examples are presented to illustrate the effectiveness of this strategy in improving recovery results.展开更多
This study describes the evaluation of a range of approaches to semantic segmentation of hyperspectral images of sorghum plants,classifying each pixel as either nonplant or belonging to one of the three organ types(le...This study describes the evaluation of a range of approaches to semantic segmentation of hyperspectral images of sorghum plants,classifying each pixel as either nonplant or belonging to one of the three organ types(leaf,stalk,panicle).While many current methods for segmentation focus on separating plant pixels from background,organ-specific segmentation makes it feasible to measure a wider range of plant properties.Manually scored training data for a set of hyperspectral images collected from a sorghum association population was used to train and evaluate a set of supervised classification models.Many algorithms show acceptable accuracy for this classification task.Algorithms trained on sorghum data are able to accurately classify maize leaves and stalks,but fail to accurately classify maize reproductive organs which are not directly equivalent to sorghum panicles.Trait measurements extracted from semantic segmentation of sorghum organs can be used to identify both genes known to be controlling variation in a previously measured phenotypes(e.g.,panicle size and plant height)as well as identify signals for genes controlling traits not previously quantified in this population(e.g.,stalk/leaf ratio).Organ level semantic segmentation provides opportunities to identify genes controlling variation in a wide range of morphological phenotypes in sorghum,maize,and other related grain crops.展开更多
文摘The development of stationary patterns on a thin polymer surface subject to an electric field is studied by means of the hexagonal-planform weakly nonlinear stability analysis and numerical simulations. The time evolution of the interface between the air and the polymer film on the unbounded spatial domain is described by a thin film equation, incorporating the electric driving force and the surface diffusion.The nonlinear interfacial growth includes the amplitude equations and superposition of one-dimensional structures at regular orientations. The pattern selection is driven by the subcritical instability mechanism in which the relative thickness of the polymer film plays a critical role.
文摘This note is an addendum to the results of Lazer and Frederickson [1], and Lazer [4] on periodic oscillations, with linear part at resonance. We show that a small modification of the argument in [4] provides a more general result. It turns out that things are different for the correspouding Dirichlet boundary value problem.
文摘We present iterative numerical methods for solving the inverse problem of recovering the nonnegative Robin coefficient from partial boundary measurement of the solution to the Laplace equation. Based on the boundary integral equation formulation of the problem, nonnegativity constraints in the form of a penalty term are incorporated conveniently into least-squares iteration schemes for solving the inverse problem. Numerical implementation and examples are presented to illustrate the effectiveness of this strategy in improving recovery results.
基金This work was supported by a University of Nebraska Agri-cultural Research Division seed grant to JCS,a National Sci-ence Foundation Award(OIA-1557417)to JCS and JY,and a UCARE fellowship to AP.
文摘This study describes the evaluation of a range of approaches to semantic segmentation of hyperspectral images of sorghum plants,classifying each pixel as either nonplant or belonging to one of the three organ types(leaf,stalk,panicle).While many current methods for segmentation focus on separating plant pixels from background,organ-specific segmentation makes it feasible to measure a wider range of plant properties.Manually scored training data for a set of hyperspectral images collected from a sorghum association population was used to train and evaluate a set of supervised classification models.Many algorithms show acceptable accuracy for this classification task.Algorithms trained on sorghum data are able to accurately classify maize leaves and stalks,but fail to accurately classify maize reproductive organs which are not directly equivalent to sorghum panicles.Trait measurements extracted from semantic segmentation of sorghum organs can be used to identify both genes known to be controlling variation in a previously measured phenotypes(e.g.,panicle size and plant height)as well as identify signals for genes controlling traits not previously quantified in this population(e.g.,stalk/leaf ratio).Organ level semantic segmentation provides opportunities to identify genes controlling variation in a wide range of morphological phenotypes in sorghum,maize,and other related grain crops.
