Adaptive output control of uncertain nonlinear systems with non-symmetric dead-zone input

This paper deals with the adaptive output feedback control problem of a class of uncertain nonlinear systems with an unknown non-symmetric dead-zone nonlinearity. The nonlinear system considered here is dominated by a triangular system without zero dynamics satisfying polynomial growth in the unmeasurable states. An adaptive control scheme is developed without constructing the dead-zone inverse. The proposed adaptive control scheme requires only the information of bounds of the slopes and the breakpoint of dead-zone nonlinearity. The novelty of this paper is that a universal-type adaptive output feedback controller is numerically constructed by using a sum of squares (SOS) optimization algorithm, which ensures the boundedness of all the signals in the adaptive closed-loop without knowing the growth rate of the uncertainties. An example is presented to show the effectiveness of the proposed approach.     

State estimation of nonlinear dynamical systems using nonlinear update based Unscented Gaussian Sum Filter

Two attractive features of Unscented Kalman Filter (UKF) are: (1) use of deterministically chosen points (called sigma points), and (2) only a linear dependence of the number of sigma points on the number of states. However, an implicit assumption in UKF is that the prior conditional state probability density and the state and measurement noise densities are Gaussian. To avoid the restrictive Gaussianity assumption, Gaussian Sum-UKF (GS-UKF) has been proposed in literature that approximates all the underlying densities using a sum of Gaussians. However, the number of sigma points required in this approach is significantly higher than in UKF, thereby making GS-UKF computationally intensive. In this work, we propose an alternate approach, labeled Unscented Gaussian Sum Filter (UGSF), for state estimation of nonlinear dynamical systems, corrupted by Gaussian state and measurement noises. Our approach uses a Sum of Gaussians to approximate the non-Gaussian prior density. A key feature of this approximation is that it is based on the same number of sigma points as used in UKF, thereby resulting in similar computational complexity as UKF. We implement the proposed approach on two nonlinear state estimation case studies and demonstrate its utility by comparing its performance with UKF and GS-UKF.     

彩色像对的邻域边界差值模板匹配算法研究

分析了区域算法中SAD在非纹理区域容易产生错误匹配的缺点,提出了一种利用邻域边界差值模板的彩色图像立体匹配新算法。该算法利用了图像的边界信息来动态选择基准点邻域范围内的边界点,以该点为中心取一像素邻域作为伴随窗,将伴随窗的颜色信息加入到评价函数中以达到减少非纹理区域错误匹配目的。该算法的实验结果通过Middlebury网站评测,证明能够得到浓密视差图的同时有效地减少了非纹理区域的错误匹配。而且该算法简单易于实现,精度较高,具有良好的匹配效率。     

节能量计算方法探讨

目前,计算节能量的方法主要有两种:基准单耗对比法和累积和法。国内多采用基准单耗对比法计算节能量。此方法简单、方便,但是在技术措施实施前后产品产量有较大变化时,此方法的计算值存在误差,不能如实监测技术措施的实施效果。与基准单耗对比法相比,累积和法能更真实地计算出企业节能技术措施所带来的节能量,反映出能源消耗的趋势性变化,监测节能技术措施是否、以及具体何时发挥了作用。分析了累积和法在计算节能量时较基准单耗对比法更为真实的原因,并介绍如何使用累积和法监测节能技术措施的实施效果。以某化肥企业为例,结合该企业2009年的能源审计工作,运用累积和法,对该企业的节能量进行计算,分析该企业节能技术措施的实施效果,并发现能源审计期间一些引起企业能耗变化的因素,实例验证了累积和法节能量计算的准确性和有效性。     

基于编码发射与自适应波束形成的超声成像

与传统的延时叠加(DAS)波束形成的成像方法相比,Capon算法可以有效地提高医学超声成像的横向分辨率,但不能提高成像的对比度。该文提出一种新的成像方法Chirp_Capon算法,即将超声编码发射技术与Capon算法相结合,利用编码信号优异的相关特性来弥补Capon算法在对比度上的不足,从而得到了较好的成像结果。仿真结果表明相对于Capon算法,该算法不仅具有较高横向分辨率,而且可以有效提高图像的对比度和信噪比。     

自适应的H.264快速运动估计算法

H.264/AVC是ITU-T和ISO/IEC联合制定的最新视频压缩标准。运动估计作为H.264算法中计算最复杂的部分,在很大程度上影响着整个算法的性能。为提高运动估计算法的搜索效率,提出了一种自适应的快速运动估计算法。实验结果表明,该算法可大幅提升编码速度,而PSNR仅略有下降,为工程实现提供了一种可行的选择。     

Parameter extraction of the SOFC mathematical model based on fractional order version of dragonfly algorithm

Fuel cells are considered as new kinds of clean energy sources. This study presents a method for optimal unknown parameters identification of a Solid Oxide Fuel Cell (SOFC). The main purpose is to provide a proper method for the minimization of the sum of squared error (SSE) between the outputted voltage of the empirical data and the obtained data. To provide an efficient methodology, a modified metaheuristic algorithm, called the Fractional Order Dragonfly algorithm is utilized. To validate the utilized model, it is evaluated under various conditions of pressure and temperature. Final achievements are put in comparison with several different latest approaches and the achievements show the priority of the suggested methodology toward the comparative methods in model parameter identification of the SOFC.     

Flow rate measurement of individual oil well using multivariate thermal analysis

Flow measurement of individual oil wells mainly consisted of using test-separator units with many limitations including time and cost consuming, uncertainty of well isolation, and need to closing the co-line wells. The multivariate regression of thermogravimetric data were used to predict the accurate productivity of oil wells using a single sample-point at the blend-oil pipe-line. The results revealed that the Weighted Sum Model was appropriate for oils, which their thermal traces were significantly different from each other. The thermogravimetric data was arranged in a two-way array by taking the number of oil samples and the thermal signal intensities as columns and rows, respectively. The data matrix was decomposed using the commend of Matrix Left Division in MATLAB and the rank of individual oil wells was determined as a column vector. The error vector corrected the blend equation by considering the catalytic pyrolysis and eutectic point in higher and lower temperatures, respectively. The model predicted the accurate productivity of individual oil wells in an offshore oil field after 2010.     

Lebensdauervorhersage für Getriebegehäuse aus Aluminiumdruckguss mit dem Örtlichen Konzept

Pressure cast transmission housings are structural components of complex shape, which have to fulfil, amongst others, the requirements of structural durability, saving as much weight as possible. The numerical proof of structural durability is carried out using the local strain approach. One challenge is to consider the inhomogenious material properties, as a consequence of the casting process. It shows, that local porosity is the determining factor for the components fatigue life. Coming from the experiences made using the basic version of the local strain approach the methods used to successfully adjust the procedure for calculating pressure cast components under constant and variable amplitudes are described.