基于改进余弦组合窗的解耦方程弹性波逆时偏移

弹性波矢量波场逆时偏移可以综合利用纵横波场信息,对地下空间进行清晰成像,且对于成像介质没有角度限制,可以对复杂构造进行更清晰的成像.而弹性波逆时偏移中最重要的就是求解波动方程的算法,其直接影响成像的精度以及效率.本文引进电力系统谐波分析中常用的余弦组合窗函数,并通过一种新的优化算法得到了改进的余弦组合窗函数从而得到优化后的有限差分算子.并将此算子应用于解耦方程的矢量波场分离算法从而提高了成像精度.数值测试表明基于新算法的逆时偏移的成像精度和清晰度得到了明显的提高.

基于全解耦奇偶方程的动态系统执行器故障检测与识别

给出了基于全解耦奇偶方程的动态系统执行器故障的检测与识别方法。讨论了全解耦奇偶向量的产生方法,给出了全解耦奇偶向量的存在条件,并结合卡尔曼滤波方法得到了故障模型参数的估计方法。最后给出了仿真实例。结果表明,全解耦奇偶方程方法能估计出动态系统执行器故障模型。

倾斜二维指向镜跟踪系统速率方程

本文针对非传统二维指向镜跟踪系统,建立了跟踪器入射光轴角速率与仪器框架轴角速率的运动学耦合方程,给出了完整跟踪解耦关系式,并对解耦关系式进行了适当的小角度近似和线性化处理,从而实现成像跟踪闭环控制环路。仿真结果验证了解耦关系式的正确性和有效性。经过近似处理后不但有效解决了算法的实时性问题,且对跟踪器镇定时间无较大影响。

卫星导航系统传感器故障识别

传感器是卫星导航系统中的重要部件,其故障的检测和识别对提高系统可靠性具有重要意义。给出了一种基于模糊逻辑的卫星导航系统传感器故障识别方法。首先采用T-S模糊模型描述卫星导航系统,然后应用全解耦奇偶方程的方法进行故障检测,并利用卡尔曼滤波器进行故障参数识别。仿真结果表明,针对导航系统中多个传感器同时发生故障的情况,此方法能有效检测故障,并能准确识别故障参数。

弹性波逆时偏移的角度域共成像点道集提取方法

对于多分量地震勘探,由于介质中纵、横波的耦合作用,多波角道集存在能量串扰和低波数噪声干扰等问题。针对横波Poynting矢量构建过程中存在的应力串扰问题,基于解耦延拓方程及伪横波应力构建方法,对质点振动速度和应力进行解耦,实现了无能量串扰的纵波和横波Poynting矢量构建;在基于Poynting矢量提取PP波反射角和PS波反射角的基础上,提出了基于弹性逆时偏移的PP波和PS波角道集提取方法;针对PP波角度域共成像点道集存在的低波数噪声干扰问题,提出了角度域共成像点道集的角度衰减叠加策略,提高了偏移成像精度。应用模型数据验证了方法的正确性。

声反射成像测井弹性波逆时偏移方法对比研究

声反射成像测井中的声波逆时偏移算法在处理单分量偶极横波反射资料时可获得高精度成像结果,而面对单极声源中的多波多分量弹性波反射资料时,由于其包含PP、PS、SP和SS等多种波型分量,基于声波方程的逆时偏移处理结果中出现单反射界面对应多同相轴的偏移假象.首先在声反射成像测井中实现了纵横波耦合弹性波逆时偏移和基于Helmholtz分解的弹性波逆时偏移,在此基础上首次提出和实现了基于一阶速度-应力纵横波解耦方程的弹性波逆时偏移,通过纵横波解耦结果和成像结果对三种声反射成像测井弹性波逆时偏移进行对比研究,数值算例表明基于纵横波耦合的弹性波逆时偏移无法处理转换波(PS或SP)成像问题;Helmholtz分解虽可实现纵横波解耦但同时引起反射波振幅和相位改变,进而导致包含S波的成像分量出现极性反转问题.基于一阶速度-应力纵横波解耦方程的弹性波逆时偏移可有效处理多波多分量反射资料偏移成像,消除转换分量成像噪声,解决S波分量成像极性反转,为声反射成像测井弹性波逆时偏移算法奠定了有力的理论基础.

Explicit Solutions for a New (2+1)-Dimensional Coupled mKdV Equation

An integrable （2＋1）-dimensional coupled mKdV equation is decomposed into two （1 ＋1）-dimensional soliton systems, which is produced from the compatible condition of three spectral problems. With the help of decomposition and the Darboux transformation of two （1＋1）-dimensional soliton systems, some interesting explicit solutions of these soliton equations are obtained.

Two-Soliton Solutions and Interactions for the Generalized Complex Coupled Kortweg-de Vries Equations

Kortweg-de Vries （KdV）-typed equations have been used to describe certain nonlinear phenomena in fluids and plasmas. Generalized complex coupled KdV （GCCKdV） equations are investigated in this paper. Through the dependent variable transformations and symbolic computation, GCCKdV equations are transformed into their bilinear forms, based on which the one- and two-soliton solutions are obtained. Through the interactions of two solitons, the regular elastic collision are shown. When the wave numbers are complex, three kinds of solitonie collisions are presented： （i） two solitons merge and separate from each other periodically; （ii） two solitons exhibit the attraction and repulsion nearly twice, and finally separate from each other after such type of interaction; （iii） two solitons are ftuctuant in the central region of the collision. Propagation features of solitons are investigated with the effects of the coefficients in the GCCKdV equations considered. Velocity of soliton increase with the a increasing. Amplitude of v increase with the a increasing and decrease with the β increasing.

Existence and Regularity of Solution to a Thermally Coupled Nonstationary System

In this paper, a coupled elliptic-parabolic system modeling a class of engineering problems with thermal effect is studied. Existence of a weak solution is first established through a result of Meyers＇ theorem and Schauder fixed point theorem, where the coupled functions σ（s）,k（s） are assumed to be bounded in the C（IR×（0, T））. If σ（s）,k（s） are Lipschitz continuous we prove that solution is unique under some restriction on integrability of solution. The regularity of the solution in dimension n ≤ 2 is then analyzed under the assumptions on σ（s） ∈w^1,∞（Ω×（0, T）） and the boundedness of σ＇（s） and σ″（s）.

New Exact Solutions and Special Coherent Structures for Coupled Integrable Dispersionless Equation

Using improved homogeneous balance method, we obtain new exact solutions for the coupled integrable dispersionless equation. On the basis of these exact solutions, we find some new interesting coherent structures by selecting arbitrary functions appropriately.

Analytic Expansion for Ground-State Wavefunction of Time-Dependent Strong-Coupling Schrodinger Equation

The new method proposed recently by Friedberg, Lee, and Zhao is extended to obtain an analytic expansion for the ground-state wavefunction of a time-dependent strong-coupling Schroedinger equation. Two different types of the time-dependent harmonic oscillators are considered as examples for application of the time-dependent expansion. It is show that the time-dependent strong-coupling expansion is applicable to the time-dependent harmonic oscillators with a slowly varying time-dependent parameter.

Mathematical Model and Intelligent Control of a Quadcopter, with Non-conventional Membership Functions

This paper shows detailed steps for modeling a quadcopter with Euler-Lagrange equations, followed by controlling it with intelligent control that includes states decoupling. In addition, this control shows non-conventional membership functions for the most instable states, in order to get a fast and effective response.

The Filtration Problems of Fluid Containing Solute Through Layered Porous Media

In this paper, we consider the problem (θ(x,U))_t=(K(x,U)U_x)_x-(K(x,U))_x (x,t)∈G_T (θ(x,U)V(x,t))_t=(DθV_x)_x+(V(KU_x-K))_x,(x,t)∈G_T, u(x,0)=u_0(x),V(x,0),(x,0)=V_0(x),0≤x≤2, U(0,t)=h_0(t),U(2,t)=h_2(t),0≤t≤T, V(0,t)=g_0(t),V(2,t)=g_2(t),0≤t≤T. Where, θ(x,U)=θ_1(x,U) when (x,t)∈D_1={0≤x<1,0≤t≤T};θ(x,U)=θ_2(x,U),(x,t)∈D_2={1<x≤2,0≤t≤T}.K(x,U)=K_i(x,U),(x,t)∈D_i. θ_i, K_i are the Moisture content and hy draulic conductivity of porous Media on D_i respectively. V be the the concentration of solute in the fluid. In addition we also require that U, V, (K(x,U)U_x-1) and DθV_x+V(KU_x-K) are continu ous at x=1. We prove the exisence, uniqueness and large time behavior of the problem by the method of reg ularization.

New Exact Solutions for a Class of Nonlinear Coupled Differential Equations

More new exact solutions for a class of nonlinear coupled differential equations are obtained by using a direct and efficient hyperbola function transform method based on the idea of the extended homogeneous balance method.

冷轧带材整辊式板形仪通道耦合与解耦

板形检测是提高板形质量的基础和关键。为保证带材表面不被划伤,整辊式板形仪应运而生。由于结构的特殊性,整辊式板形仪在某一通道受压力时不仅会对本通道信号产生作用,还会对邻近通道信号产生显著干扰,引起检测误差,因此需要对其进行解耦处理。为解决这一问题,首先通过力学分析提出了通道耦合的概念和影响矩阵模型,然后通过标定试验获得影响矩阵的数值,最终通过解耦方程消除通道间的相互干扰。仿真试验和工业应用证明,提出的理论和方法可有效提高板形检测和控制精度。

Two Second-Order Ecient Numerical Schemes for the Boussinesq Equations

In this paper,we construct two fully decoupled,second-order semi-discrete numerical schemes for the Boussinesq equations based on the scalar auxiliary variable(SAV)approach.By introducing a scalar auxiliary variable,the original Boussinesq system is transformed into an equivalent one.Then we discretize it using the second-order backward di erentiation formula(BDF2)and Crank-Nicolson(CN)to obtain two second-order time-advanced schemes.In both numerical schemes,a pressure-correction method is employed to decouple the velocity and pressure.These two schemes possess the desired property that they can be fully decoupled with satisfying unconditional stability.We rigorously prove both the unconditional stability and unique solvability of the discrete schemes.Furthermore,we provide detailed implementations of the decoupling procedures.Finally,various 2D numerical simulations are performed to verify the accuracy and energy stability of the proposed schemes.

基于两种波场分离方法的弹性波逆时偏移对比研究

弹性波逆时偏移是一种以矢量波理论为基础的深度域偏移算法,该算法在波场传播过程中能够正确处理波形能量的转换,保持地震波的动力学和运动学特征.然而,传统弹性波逆时偏移由于成像时纵横波未分离,导致串扰噪声的产生,降低成像精度.为压制弹性波逆时偏移成像串扰噪声,本文对基于Helmholtz分解的波场分离与基于解耦方程的波场分离方法进行研究和分析,并测试对比相应的弹性波逆时偏移成像效果.均匀各向同性介质波场分离测试表明,基于Helmholtz分解分离波场的振幅与相位均发生改变,需要额外校正;而基于解耦方程的波场分离方法可以保持原始波场相位与振幅特征不变.Marmousi截断模型测试表明,基于Helmholtz分解分离波场的弹性波逆时偏移成像振幅与相位发生改变,且存在极性反转现象;基于解耦方程波场分离方法的弹性波逆时偏移成像保持原始波场矢量特征,无极性反转现象,成像效果较为理想.

Exponential Attractors for the Ginzburg-Landau-BBM Equations

In this paper, the existence of the exponential attractors for the Ginzburg- Landau-BBM equations with periodic initial and boundary conditions are obtained by using the squeezing property and the operator dccomposition method.

航空发动机数控系统多故障识别

提出了一种基于模糊逻辑的航空发动机数控系统多故障的识别方法.首先采用Takagi-Sugeno(T-S)模糊模型描述一种涡喷发动机数控系统的非线性模型,然后应用全解耦奇偶方程进行多故障的检测和隔离,并结合卡尔曼滤波器识别出传感器和执行器故障参数.仿真结果表明,针对传感器和执行器同时发生故障的情况,此方法能有效检测故障,并能准确识别出故障参数.

Integrating 1D and 2D hydrodynamic,sediment transport model for dam-break flow using finite volume method

The purpose of this study is to set up a dynamically linked 1D and 2D hydrodynamic and sediment transport models for dam break flow.The 1D-2D coupling model solves the generalized shallow water equations,the non-equilibrium sediment transport and bed change equations in a coupled fashion using an explicit finite volume method.It considers interactions among transient flow,strong sediment transport and rapid bed change by including bed change and variable flow density in the flow continuity and momentum equations.An unstructured Quadtree rectangular grid with local refinement is used in the 2D model.The intercell flux is computed by the HLL approximate Riemann solver with shock captured capability for computing the dry-to-wet interface for all models.The effects of pressure and gravity are included in source term in this coupling model which can simplify the computation and eliminate numerical imbalance between source and flux terms.The developed model has been tested against experimental and real-life case of dam-break flow over fix bed and movable bed.The results are compared with analytical solution and measured data with good agreement.The simulation results demonstrate that the coupling model is capable of calculating the flow,erosion and deposition for dam break flows in complicated natural domains.