Simulation of plant disease is an important part of agricultural informatization. It can more intuitively and effectively disseminate knowledge of crop diseases and popularize the process of disease occurrence. In addition, disease simulation has great application values in the fields of teaching, film and games, etc. In order to simulate the process of crop diseases, this article takes wheat as the main research object. Considering the two environmental conditions of temperature and humidity, the three rust types of wheat stripe rust, leaf rust and stem rust are simulated based on textures feature. A noise function is used to simulate a distribution of spores on the wheat stems and leaves, and these noise properties can be adjusted according to the type of rust to achieve a more realistic simulation effect. The position of disease on the surface of plant can be simulated by changing the distribution of three-color components of RGB on a mask map. We adjust the surface map of a crop model into a specified position with a shader and then take a spherical shape whose radius is gradually increasing to specify the range of infected area. Finally we simulate a visualization of the whole spread process of a plant from intact to complete disease. Experimental results show that the simulation algorithm proposed in this paper is effective with realistic results and of good universality. The ideas of this simulation algorithm can provide a reference for various disease simulations of other kinds of plants.
The target tracking by unmanned aerial vehicle (UAV) has become a hot research topic in the field of computer vision.UAV target tracking can be applied to fire fighting, military and other important fields.At present, most UAV target tracking algorithms are based on traditional RGB cameras combined with deep learning algorithms. However, such methods are hard to deal with motion blur caused by UAV body jitter. Moreover, traditional RGB cameras have poor performance of imaging on low-illumination or over-exposure scenes. In order to solve the above problems, this paper presents an approach which takes the UAV with DAVIS event camera for target tracking, and designs a dual mode fusion tracking network based on events and grayscale, To better train the network, this paper employs the Vicon motion capture system to make the target tracking data sets:Event-APS 28 under the UAV perspective, ensuring that the target can be tracked effectively according to the image information even in complex lighting scenes.
The complex underwater environment makes it difficult to obtain 3D fish models, leading to the fact that many automated research work based on 3D fish data cannot be carried out. This paper proposes a 3D fish body parametric modeling method. Firstly, we use the standard fish body template constructed by a professional modeler to register the 3D fish body data collected by the scanner, and construct a 3D fish body mesh dataset with consistent topological structure; Secondly, we apply the principal component analysis method to model and analyze the 3D fish body mesh model in the dataset establishing a parameterized representation model of the fish body. We take the collected grass carp data to verify the effectiveness of the above approach. The experimental results show that the root mean square error between the vertices of the registered 3D fish model and the real scanned fish model is only 0.691 3 mm. By changing the weight parameters of the constructed 3D fish body parameterized model, a large amount of 3D fish body data can be quickly generated.
Global existence and blow-up of solutions to a nonlinear nonlocal reaction-diffusion system with time-dependent coefficients and inner absorption terms under nonlinear boundary conditions are studied.Energy expressions are formulated.By using the technique of Sobolev inequalities and other differential ones,the energy satisfying a differential inequality under certain conditions is deduced.Finally,the global existence and lower bound estimates of blow up time are obtained respectively.
The analytical method and exact solutions of the population balance equation involving growth and breakage processes are investigated in this paper. Partial symmetries, group invariant solutions and reduced integro-ordinary differential equations of the population balance equation are found by scaling transformation group analysis. Explicit exact solutions of the population balance equation are obtained by solving the reduced integro-ordinary differential equations with the method of trial function. The dynamic behavior of explicit exact solutions is analyzed. The obtained group invariant solutions can provide interpretation for the physical processes model, on the other hand, these obtained exact solutions can also be used to verify the correctness and accuracy of numerical solutions.
By using the fixed point theorem in Banach space and the inequality technique,we discuss the existence of positive solution for a class of higher order nonlinear neutral difference equations with positive and negative coefficients and multiple variable delays.Under certain conditions,we establish a few new nonoscillation criteria.Our results improve and extend some known results.
In this paper,the classical steepest descent method has been used to construct the zeros of a class of Lipschitz continuous and quasi-inverse strongly monotone operators.Under very mild conditions,a weak convergence theorem is established.Applying our weak convergence theorem to the split common fixed point problem,some new results are deduced which improve the recent known results in literature.
The model of branching process {Zn,n∈N} affected by communicable diseases in independent random environment is proposed,and the limit properties of this model are discussed.Under the normalization factors {Sn,n∈N} and {Un,n∈N},the normalization processes {W?n,n∈N} and {Wˉn,n∈N} are studied,the sufficient conditions of {W?n,n∈N} and {Wˉn,n∈N} a.s.and L1 convergence are given; the sufficient condition of {W?n,n∈N}L2 convergence,a sufficient condition and a necessary condition for the limit of {W?n,n∈N} converging to a non-degenerate at 0 random variable are obtained.
The higher order convective Cahn-Hilliard type equation is a kind of sixth-order evolution equation with fourth-order nonlinearity term.A linearized finite difference scheme is presented by using Taylor formula.The first time level is a two-layers implicit scheme,while the other time levels are three-layers implicit schemes.In the derivation of the scheme,nonlinear terms are discretized by central difference quotient.A theoretical analysis is carried out by the energy argument and mathematical induction. The uniqueness and convergence of the numerical solution are proved in L2 norm rigorously.The convergence order is two in time and space.Some numerical results are presented to demonstrate the efficiency of the difference scheme.
Based on the generalized autoregressive score (GAS) and heterogeneous autoregressive of realized volatility (HAR-RV) models, introduce investor sentiment factor, this paper constructs HAR-RV GAS and HAR -RV SENT GAS volatility models, aim to predict the superior predictive ability (SPA) test, analyze the ability of in-sample data fitting and out of sample volatility prediction respectively.Through VAR prediction sequence diagram and average quantile loss function, the effect of VaR prediction is analyzed empirically. The results show that HAR-RV-SENT GAS model is the best in volatility and VaR prediction ability, followed by HAR -RV GAS model. This study can provide theoretical reference for financial investors and risk managers.
