基于高分一号遥感影像的水体提取方法对比分析与改进

以高分一号遥感影像为数据源,以安徽省黄山市屯溪流域内的东方红水库为研究对象,采用单波段阈值法、两波段差值法、波段比值法、归一化差分水体指数(NDWI)法、归一化差分植被指数(NDVI)法共5种水陆像元度量方法,分别应用平均值法和最大类间方差迭代法两种阈值选取方法对东方红水库进行水体提取,探索最大类间方差迭代法在水体提取变量上的改进效果,在此基础上提出了一种改进的最大类间方差联合水体提取法,并对比了改进前后的水体提取效果。结果表明:改进后的水体提取方法可以很好地降低影像提取中产生的噪点,提高水体提取的精度,提取成果的平均相对误差为4.69%,决定系数为0.8579,相比于改进前平均相对误差降低了0.68%,决定系数提高了0.0539。

体内张拉成形空间网格结构自振特性研究

体内张拉成形空间网格结构是由上弦梁、下弦(下弦管内穿索)、腹杆以及环杆等构件组成的一种新型空间结构形式,是通过对下弦管内索施加预应力张拉成形,进而改善结构受力性能的自平衡体系。文章利用ANSYS软件中的子空间迭代法,分析了体内张拉成形空间网格结构的自振特性,并针对不同的参数如矢跨比、立柱高度、预应力大小、腹杆数量以及环杆数量进行了参数分析,得出了各参数对结构的自振特性的影响。

水库水体的最大类间方差迭代遥感提取方法

针对利用遥感影像结合经验阈值提取水体信息需要进行大量试验,难以客观地确定水体与非水体分割阈值的问题,在最大类间方差法的基础上提出了最大类间方差迭代法来优化提取水库水体信息。基于高分一号(GF-1)卫星影像数据,使用归一化差分水体指数(NDWI)法初步提取了水体信息,通过形态学膨胀算法建立缓冲区,采用多次迭代最大类间方差法计算自适应阈值,用于分割水体与非水体,从而实现水体最优提取。实例验证结果表明,提出的优化方法可以有效地消除建筑等非水体地物信息的干扰,较准确地提取水库水体信息在不同时期的特征,总体分类精度与Kappa系数较最大类间方差法提取结果分别提高了9.36%和24.09%,综合精度平均提高了10.42%。

限位U型软钢阻尼器在受控结构中的位置优化

为了研究限位U型软钢阻尼器对高层混凝土框架结构的减振控制效果,以某十层混凝土框架结构为算例,采用层间位移迭代法、最优二次型性能指标损失量法和普通布置法三种优化布置方法,通过ANSYS对不同优化布置方法下的结构进行非线性时程分析,并以弹性层间位移角限值为目标函数,对该结构阻尼器布置进行最终优化.研究结果表明,在阻尼器数量一定的情况下,各优化布置方法都有一定的减振控制效果,但层间位移迭代法最好;阻尼器位置经最终优化后,结构各层弹性层间位移角明显减小,约30%,且均满足1/550的限值.说明限位U型软钢阻尼器对高层混凝土框架结构具有较好的减振控制效果.

A Real-time Modeling of Photovoltaic Array

This paper mainly aims at the modeling problem of the photovoltaic (PV) array with a 30 kW PV grid-connected generation system. An iterative method for the time-varying parameters is proposed to model a plant of PV array. The relationship of PV cell and PV array is obtained and the solution for PV array model is unique. The PV grid-connected generation system is used to demonstrate the effectiveness of the proposed method by comparing the calculated values with the actual output of the system.

Response of train-bridge system under intensive seismic excitation by random vibration method

Earthquake is a kind of sudden and destructive random excitation in nature.It is significant to determine the probability distribution characteristics of the corresponding dynamic indicators to ensure the safety and the stability of structures when the intensive seismic excitation,the intensity of which is larger than 7,acts in train-bridge system.Firstly,the motion equations of a two-dimensional train-bridge system under the vertical random excitation of track irregularity and the vertical seismic acceleration are established,where the train subsystem is composed of 8 mutually independent vehicle elements with 48 degrees of freedom,while the single-span simple supported bridge subsystem is composed of 102D beam elements with 20 degrees of freedom on beam and 2 large mass degrees of freedom at the support.Secondly,Monte Carlo method and pseudo excitation method are adopted to analyze the statistical parameters of the system.The power spectrum density of random excitation is used to define a series of non-stationary pseudo excitation in pseudo excitation method and the trigonometric series of random vibration history samples in Monte Carlo method,respectively solved by precise integral method and Newmark-βmethod through the inter-system iterative procedure.Finally,the results are compared with the case under the weak seismic excitation,and show that the samples of vertical acceleration response of bridge and the offload factor of train obeys the normal distribution.In a high probability,the intensive earthquakes pose a greater threat to the safety and stability of bridges and trains than the weak ones.

Asymptotic Iteration Method for Energies of Inversely Linear Potential with Spatially Dependent Mass

The bound-state solution of the position dependent mass Klein-Gordon equation including inversely linear potential is obtained within the framework of the asymptotic iteration method. The relation between the scalar and vector potentials is considered to S（x） = V（x）（β - 1）. In particular, it is shown that the corresponding method exactly reproduces the spectrum of linearly inversely potentials with spatially dependent mass.

A NOVEL ITERATIVE SCHEME FOR PARALLEL INTER-SYMBOL INTERFERENCE CHANNELS

In this paper,we propose a novel iterative scheme for exploiting transmit diversity using parallel independent Inter-Symbol Interference (ISI) channels. In this adaptive iterative scheme,we use EXtrinsic Information Transfer (EXIT) chart tool to choose appropriate iterative method from Itera-tive Combining (IC),used as parallel concatenation turbo-like scheme,and Turbo Equalization (TE),used as serial concatenation turbo-like scheme. It is show that the proposed iterative scheme provides excellent performance both analytically and through simulations without any compute complexity increase comparable to IC.

Motion estimation based feature selection for visual SLAM

Feature selection is always an important issue in the visual SLAM （simultaneous location and mapping） literature. Considering that the location estimation can be improved by tracking features with larger value of visible time, a new feature selection method based on motion estimation is proposed. First, a k-step iteration algorithm is presented for visible time estimation using an affme motion model; then a delayed feature detection method is introduced for efficiently detecting features with the maximum visible time. As a means of validation for the proposed method, both simulation and real data experiments are carded out. Results show that the proposed method can improve both the estimation performance and the computational performance compared with the existing random feature selection method.

INVERSE QR ITERATIVE METHOD FOR SUBSPACE TRACKING

The Bi-LS method based on QR decomposition provides a convenient framework for de-veloping efficient subspace tracking algorithms.To overcome the shortcoming of the backsubstitution step and improve the parallel architecture of the Bi-LS algorithms,a Bi-LS subspace tracking algorithm based on Inverse QR(IQR) decomposition is developed.The proposed IQR iterative algorithm for subspace tracking is well suited for the parallel implementation in the systolic array.Simulation results are presented to illustrate the effectiveness of the proposed IQR subspace tracking algorithm.

Some results on the regularization of LSQR for large-scale discrete ill-posed problems

LSQR, a Lanczos bidiagonalization based Krylov subspace iterative method, and its mathematically equivalent conjugate gradient for least squares problems(CGLS) applied to normal equations system, are commonly used for large-scale discrete ill-posed problems. It is well known that LSQR and CGLS have regularizing effects, where the number of iterations plays the role of the regularization parameter. However, it has long been unknown whether the regularizing effects are good enough to find best possible regularized solutions. Here a best possible regularized solution means that it is at least as accurate as the best regularized solution obtained by the truncated singular value decomposition(TSVD) method. We establish bounds for the distance between the k-dimensional Krylov subspace and the k-dimensional dominant right singular space. They show that the Krylov subspace captures the dominant right singular space better for severely and moderately ill-posed problems than for mildly ill-posed problems. Our general conclusions are that LSQR has better regularizing effects for the first two kinds of problems than for the third kind, and a hybrid LSQR with additional regularization is generally needed for mildly ill-posed problems. Exploiting the established bounds, we derive an estimate for the accuracy of the rank k approximation generated by Lanczos bidiagonalization. Numerical experiments illustrate that the regularizing effects of LSQR are good enough to compute best possible regularized solutions for severely and moderately ill-posed problems, stronger than our theory, but they are not for mildly ill-posed problems and additional regularization is needed.

LIL behavior for B-valued strong mixing random variables

Given a sequence of mixing random variables {X1,Xn;n≥1} taking values in a separable Banach space B,and Sn denoting the partial sum,a general law of the iterated logarithm is established,that is,we have with probability one,lim supn→∞‖Sn‖/cn = α0 < ∞ for a regular normalizing sequence {cn}1,where α 0 is a precise value.

Iterative Algorithm with Mixed Errors for Solving a New System of Generalized Nonlinear Variational-Like Inclusions and Fixed Point Problems in Banach Spaces

A new system of generalized nonlinear variational-like inclusions involving A- maximal m-relaxed η-accretive （so-called, （A, η）-accretive in [36]） mappings in q-uniformly smooth Banach spaces is introduced, and then, by using the resolvent operator technique associated with A-maximal m-relaxed ~/-accretive mappings due to Lan et al., the exis- tence and uniqueness of a solution to the aforementioned system is established. Applying two nearly uniformly Lipschitzian mappings 81 and 82 and using the resolvent operator technique associated with A-maximal m-relaxed ~？-accretive mappings, we shall construct a new perturbed N-step iterative algorithm with mixed errors for finding an element of the set of the fixed points of the nearly uniformly Lipschitzian mapping Q = （S1, S2） which is the unique solution of the aforesaid system. We also prove the convergence and stability of the iterative sequence generated by the suggested perturbed iterative algorithm under some suitable conditions, The results presented in this paper extend and improve some known results in the literature.

A novel method of Newton iteration-based interval analysis for multidisciplinary systems

A Newton iteration-based interval uncertainty analysis method(NI-IUAM) is proposed to analyze the propagating effect of interval uncertainty in multidisciplinary systems. NI-IUAM decomposes one multidisciplinary system into single disciplines and utilizes a Newton iteration equation to obtain the upper and lower bounds of coupled state variables at each iterative step.NI-IUAM only needs to determine the bounds of uncertain parameters and does not require specific distribution formats. In this way, NI-IUAM may greatly reduce the necessity for raw data. In addition, NI-IUAM can accelerate the convergence process as a result of the super-linear convergence of Newton iteration. The applicability of the proposed method is discussed, in particular that solutions obtained in each discipline must be compatible in multidisciplinary systems. The validity and efficiency of NI-IUAM is demonstrated by both numerical and engineering examples.