L型阵水下目标方位和距离联合最大似然估计

空间目标定位是阵列信号处理领域中的研究热点,广泛应用于雷达、声纳、通信、射电天文、医学诊断、地震遥感等众多领域。传统的水下声源定位仅获取目标声源的深度和距离信息,却无法估计目标的方位信息。针对这一问题,在充分考虑水下声传播模型的基础上,利用L型阵列固有的结构特征,将最大似然估计技术应用到水下目标定位,提出一种基于L型水听器阵列的水下目标方位与距离联合最大似然估计算法。研究表明:最大似然估计法可有效突破传统波束形成分辨力“瑞利限”的限制,提高水下目标定位的分辨能力和精度。计算机仿真分析显示,在单目标和相干双目标的场景中,文中所提出的方法均具有更为尖锐的谱峰及更低的旁瓣水平,可对水下目标进行有效的方位角和距离联合估计。

基于高阶幂的单快拍LDACS系统波达方向估计

L波段数字航空通信系统(L band digital aeronautical communication system,LDACS)是未来航空宽带通信重要的基础设施之一,针对LDACS信号容易受到相邻波道大功率测距仪(distance measuring equipment,DME)信号干扰的问题,提出了联合正交投影干扰抑制与单快拍稀疏分解的波达方向(direction of arrival,DOA)估计方法。通过子空间投影抑制DME干扰,然后使用单快拍数据构建伪协方差矩阵,对伪协方差矩阵求高阶幂,之后进行奇异值分解,并利用约束条件求解稀疏解得到期望信号来向的估计值。所提方法使用高阶伪协方差矩阵降低了噪声影响,仅用单快拍就可以准确估计LDACS信号的入射方向。仿真结果表明,改进单快拍高级幂(improved single snapshot high order power,ISS-HOP)L1-SVD算法的估计精度优于ISS-HOP-MUSIC算法。该方法可以有效抑制DME干扰,提高OFDM接收机性能。

A PRIORI L_2 ERROR ESTIMATES FOR A NONLINEAR PARABOLIC SYSTEM BASED ON COMBINING THE METHOD OF CHARACTERISTICS WITH MIXED FINITE ELEMENT PROCEDURE

A nonlinear parabolic system is derived to describe incompressible nuclear waste-disposal contamination in porous media. A sequential implicit tirne-stepping is defined, in which the pressure and Darcy velocity of the mixture are approximated simultaneously by a mixed finite element method and the brine, radionuclid and heat are treated by a combination of a Galerkin finite element method and the method of characteristics. Optimal-order convergence in L2 is proved. Time-truncation errors of standard procedures are reduced by time stepping along the characteristics of the hyperbolic part of the brine, radionuclide and heal equalios, temporal and spatial error are lossened by direct compulation of the velocity in the mixed method, as opposed to differentiation of the pressure.

L^p-L^q decay estimates of solutions to Cauchy problems of thermoviscoelastic systems

L^p- L^q decay estimate of solution to Cauchy problem of a linear thermoviscoelastic system is studied. By using a diagonalization argument of frequency analysis, the coupled system will be decoupled micrologically. Then with the help of the information of characteristic roots for the coefficient matrix of the system, L^p- L^q decay estimate of parabolic type of solution to the Cauchy problem is obtained.

SOME INTEGRAL MEAN ESTIMATES FOR POLYNOMIALS

In this paper we establish L^q inequalities for polynomials, which in particular yields interesting generalizations of some Zygmund-type inequalities.

<i>L</i>^∞-Error Estimate of Schwarz Algorithm for Noncoercive Variational Inequalities

The Schwarz method for a class of elliptic variational inequalities with noncoercive operator was studied in this work. The author proved the error estimate in L∞-norm for two domains with overlapping nonmatching grids using the geometrical convergence of solutions and the uniform convergence of subsolutions.

Endpoint Estimates for Commutators of Fractional Integrals Associated to Operators with Heat Kernel Bounds

Let L be the infinitesimal generator of an analytic semigroup on L;（R;）with pointwise upper bounds on heat kernel,and denote by L;the fractional integrals of L.For a BMO function b（x）,we show a weak type Llog L estimate of the commutators [b,L;]（f）(x) = b（x）L;（f）(x)-L;（bf）(x).We give applications to large classes of differential operators such as the Schr¨odinger operators and second-order elliptic operators of divergence form.

R^(1+1)中Maxwell-Chern-Simons-Higgs模型解的L^(∞)估计

用能量守恒估计和特征线估计的方法解决(1+1)维Maxwell-Chern-Simons-Higgs模型解的Sobolev范数增长性估计问题,给出模型有限能量解的一阶导数的L^(∞)估计,并通过改进指数增长得到解的H^(2)范数的多项式增长.

L^s- norm Estimates of Solutions for theImhomogeneous Cauchy- Riemann Equation

In this paper,we discussed the local integral solution operators of imhomogeneous Cauchy Riemann equations on an open set with piecewise C k boundary in C n,as a generalization of the solution opertators for Leray map S(z,ζ) which do not depends holomorphic on z∈D in Koppelman formula is obtained and the L s norm estimates for the solution operators are the same as that [10] in forms.

基于L型声阵列多重信号分类声源测向研究

变电站二次设备故障声源复杂多变,且在空间狭窄、位置不易接触的设备上采用接触式振动传感器采集振动信号有很大的局限性,基于非接触式的声阵列装置采集到的声音信号可以解决这些问题。针对变电站二次设备故障声源的测向问题,通过最小描述长度(Minimum Description Length,MDL)准则改进了多重信号分类算法,设计和制做了L型声阵列的声源采集装置并进行故障声源采集。结果表明,改进的算法能够有效地估计出声源数,并为二维测向提供先验条件,使得测向精度准确,且2个声源的俯仰角或方位角相同时不会相互影响。该方法能有效测量出源信号的方向且具有一定抗干扰性,对于变电站二次设备故障诊断有较好的指导意义。

A Remark on Eigenfunction Estimates by Heat Flow

In this paper, we consider L∞ estimates of eigenfunction, or more generally, the L∞ estimates of equation -Δu=fu. We use heat flow to give a new proof of the L∞ estimates for such type equations.

C_(p,q)^(s+α)-forms Solution of _b-equ ation and Its L_(p,q)~s Estimates

In this paper, by using holomorphic support f unction of strictly pseudoconvex domain on Stein manifolds and the kernel define d by DEMAILY J P and Laurent Thiebaut, we construct two integral operators T q and S q which are both belong to C s+α p,q-1 (D) and ob tain integral representation of the solution of (p,q)-form  b-equation on the boundary of pseudoconvex domain in Stein manifolds and the L s p,q extimates for the solution.

低信噪比场景下Link-16系统的联合频偏估计算法

对于Link-16数据链终端平台在低信噪比(SNR)高动态场景下的多普勒频率偏移问题,该文设计一种新的数据结构,推导了该结构下的克拉默-拉奥下界(CRLB),并在此基础上提出一种联合频域变换与时域自相关运算的分步式频偏估计算法。其基本思想是,首先对接收信号做自相关处理,然后通过频域变换进行最大值索引,结合修正因子得到多普勒频移的粗估计值,再利用时域的改进L&R算法对接收信号进行细估计,根据两步估计算法得到最终的频偏估计值。算法应用蒙特卡罗实验仿真,仿真结果表明,与传统频偏估计算法相比,该算法的归一化均方误差更接近CRLB,在多普勒频偏为[–20 kHz,20 kHz]时,估计精度可达10^(–5)。在低信噪比环境下,所提算法能达到较为理想的估计效果,适用于Link-16数据链通信。

OPTIMAL ERROR ESTIMATE IN L~∞(J;L^2(Ω)) NORM OF FEM FOR A MODEL FOR COMPRESSIBLE MISCIBLE DISPLACEMENT IN POROUS MEDIA

We’ll study the FEM for a model for compressible miscible displacement in porous media which includes molecular diffusion and mechanical dispersion in one-dimensional space.A class of vertices-edges-elements interpolation operator ink is introduced.With the help of ink(not elliptic projection),the optimal error estimate in L∞(J;L2(Ω)) norm of FEM is proved.

Joint 2D DOA and Doppler frequency estimation for L-shaped array using compressive sensing

A joint two-dimensional(2D)direction-of-arrival(DOA)and radial Doppler frequency estimation method for the L-shaped array is proposed in this paper based on the compressive sensing(CS)framework.Revised from the conventional CS-based methods where the joint spatial-temporal parameters are characterized in one large scale matrix,three smaller scale matrices with independent azimuth,elevation and Doppler frequency are introduced adopting a separable observation model.Afterwards,the estimation is achieved by L1-norm minimization and the Bayesian CS algorithm.In addition,under the L-shaped array topology,the azimuth and elevation are separated yet coupled to the same radial Doppler frequency.Hence,the pair matching problem is solved with the aid of the radial Doppler frequency.Finally,numerical simulations corroborate the feasibility and validity of the proposed algorithm.

采用预估L_2–L_∞滤波器的传感器信号重构

对于含有未建模动态的SIMO系统,本文提出利用预估L_2–L_∞滤波器实现对故障传感器信号的重构.通过建立故障信号与最小相对阶的测量信号间的传递函数阵,由相对阶最小的测量信号实现对故障传感器信号的预估,并在此预估信号基础上,结合L_2–L_∞滤波器存在条件,给出预估L_2–L_∞滤波器设计及其参数求解方法.通过将预估L_2–L_∞滤波器、L_2–L_∞滤波器及部分状态观测器在飞行器故障传感器信号重构中的对比,并由蒙特卡洛仿真实验,预估L_2–L_∞滤波器实现的由俯仰角速度对迎角信号的重构精度最高,且当系统矩阵及控制输入矩阵的未建模动态在±30%及±20%内浮动时,迎角重构误差小于0.1?.

An improved estimation of distribution algorithm for multi-compartment electric vehicle routing problem

The multi-compartment electric vehicle routing problem(EVRP)with soft time window and multiple charging types(MCEVRP-STW&MCT)is studied,in which electric multi-compartment vehicles that are environmentally friendly but need to be recharged in course of transport process,are employed.A mathematical model for this optimization problem is established with the objective of minimizing the function composed of vehicle cost,distribution cost,time window penalty cost and charging service cost.To solve the problem,an estimation of the distribution algorithm based on Lévy flight(EDA-LF)is proposed to perform a local search at each iteration to prevent the algorithm from falling into local optimum.Experimental results demonstrate that the EDA-LF algorithm can find better solutions and has stronger robustness than the basic EDA algorithm.In addition,when comparing with existing algorithms,the result shows that the EDA-LF can often get better solutions in a relatively short time when solving medium and large-scale instances.Further experiments show that using electric multi-compartment vehicles to deliver incompatible products can produce better results than using traditional fuel vehicles.

Fast Sparse Multipath Channel Estimation with Smooth L0 Algorithm for Broadband Wireless Communication Systems

Broadband wireless channels are often time dispersive and become strongly frequency selective in delay spread domain. Commonly, these channels are composed of a few dominant coefficients and a large part of coefficients are approximately zero or under noise floor. To exploit sparsity of multi-path channels (MPCs), there are various methods have been proposed. They are, namely, greedy algorithms, iterative algorithms, and convex program. The former two algorithms are easy to be implemented but not stable;on the other hand, the last method is stable but difficult to be implemented as practical channel estimation problems be-cause of computational complexity. In this paper, we introduce a novel channel estimation strategy using smooth L0 (SL0) algorithm which combines stable and low complexity. Computer simulations confirm the effectiveness of the introduced algorithm. We also give various simulations to verify the sensing training signal method.

Parameter estimation for rigid body after micro-Doppler removal based on L-statistics in the radar analysis

In traditional inverse synthetic aperture radar （ISAR） imaging of moving targets with rotational parts, the micro-Doppler （m-D） effects caused by the rotational parts influence the quality of the radar images. Recently, L. Stankovic proposed an m-D removal method based on L-statistics, which has been proved effective and simple. The algorithm can extract the m-D effects according to different behaviors of signals induced by rotational parts and rigid bodies in time-frequency （T-F） domain. However, by removing m-D effects, some useful short time Fourier transform （STFT） samples of rigid bodies are also extracted, which induces the side lobe problem of rigid bodies. A parameter estimation method for rigid bodies after m-D removal is proposed, which can accurately re- cover rigid bodies and avoid the side lobe problem by only using m-D removal. Simulations are given to validate the effectiveness of the proposed method.

时滞静态神经网络新的L_2-L_∞状态估计器设计

研究了一类含有时变时滞的静态神经网络的L_2-L_∞状态估计问题.通过利用增广的Lyapunov-Krasovskii泛函、Wirtinger积分不等式和新的L_2-L_∞性能分析方法,得到了线性矩阵不等式表示的新的L_2-L_∞状态估计器设计充分条件.所设计的状态估计器不仅能保证误差系统的全局指数稳定性,而且满足规定的L_2-L_∞性能要求.最后,数值例子验证了文中所提出设计方法的优越性.