A novel license plate location method based on wavelet transform and EMD analysis

Although various license plate location methods have been proposed in the past decades, their accuracy and ability to deal with different types of license plates still need to be improved. A robust license plate location method can raise the accuracy of the whole license plate recognition procedure. This paper proposes a robust method based on wavelet transform and empirical mode decomposition (EMD) analysis to search for the location of a license plate in an image to deal with some challenging problems in practice such as illumination changes, complex background and perspective change. By applying wavelet transform on a vehicle image and projecting the acquired details of the image, a wave crest that indicates the license plate will be generated. In order to locate the desired wave crest in the nonlinear and non-stationary projection dataset, EMD analysis is applied. Using the reconstructed projection data and the Hilbert transform of intrinsic mode function components, the position of the license plate is detected. Comprehensive experiments show that this method can locate the positions of various types of license plates with a high accuracy of 97.91% and a relatively short running time.     

A dilated LMI approach to robust performance analysis of linear time-invariant uncertain systems

This paper studies robust performance analysis problems of linear time-invariant systems affected by real parametric uncertainties. In the case where the state-space matrices of the system depend affinely on the uncertain parameters, it is know that recently developed extended or dilated linear matrix inequalities (LMIs) are effective to assess the robust performance in a less conservative fashion. This paper further extends those preceding results and propose a unified way to obtain numerically verifiable dilated LMI conditions even in the case of rational parameter dependence. In particular, it turns out that the proposed dilated LMIs enable us to assess the robust performance via multiaffine parameter-dependent Lyapunov variables so that less conservative analysis results can be achieved. Connections among the proposed conditions and existing results are also discussed concretely. Several existing results can be viewed as particular cases of the proposed conditions.     

基于改进遗传算法的开放式鲁棒融合定位方法

针对现有蜂窝网定位技术在实际应用中没有完整的定位测量参数就无法完成定位的缺点,提出了一种开放式的鲁棒融合定位新方法。该方法以信息融合技术为理论基础,融合异质异构的定位信息进行定位,在保证定位精度的前提下提高了定位算法的鲁棒性。仿真结果验证了该方法的有效性、开放性和鲁棒性。     

一类带筛选策略的改进遗传算法及其性能分析

为避免遗传算法的早熟收敛，增强算法的全局搜索和局部趋化能力，在传统保优GA中引入筛选策略，即基于种群性能和种群地域差别删去一些性能相对差的冗余个体，进而维持种群的多样性．基于典型复杂函数的数值仿真结果表明，所提算法的全局收敛速度和命中全局最优的几率相对传统方法大大提高，并对参数具有较好的鲁棒性．     

A direct method for robust adaptive nonlinear control with guaranteed transient performance

In this paper, the adaptive control problem is studied for a class of nonlinear systems in the presence of bounded disturbances. By utilizing a nice property of the studied systems, a novel Lyapunov-based control structure is developed, which avoids the possible control singularity problem in adaptive nonlinear control. The transient bounds of output tracking error are shown to be explicit functions of initial conditions and design parameters, and the control performance of the closed-loop system is guaranteed by suitably choosing the design parameters. Simulation study is provided to verify the theoretical results.     

PCS网络位置管理方案性能分析

PCS（Personal Communication Service）网络中位置管理开销昂贵；为减小开销，研究人员提出了许多种方案。研究了基于LRA（Lazy Replication Algorithm）的位置管理方案，建立了分析模型，以相邻两次呼叫期间实现位置管理所花费的开销为指标，对IS-41和LRA两者的性能进行了比较。研究表明，对于高移动性或远离归属地的用户，LRA显著优于IS-41；另一方面，对于呼叫多发生于两个服务区间或低移动性的用户，IS-41优于LRA；从总体上看，LRA性能优于IS-41。     

Maximum-entropy-type Lyapunov functions for robust stability and performance analysis

We present two Lyapunov functions that ensure the unconditional stability and robust performance of a modal system with uncertain damped natural frequency. Each Lyapunov function involves the sum of two matrices, the first being the solution to the so-called maximum-entropy equation and the second being a constant auxiliary portion. The significant feature of these Lyapunov functions is that the guaranteed robust stability region is independent of the weighting matrix, while the performance bounds are relatively tight compared to alternative approaches. Thus, these Lyapunov functions are less conservative than standard bounds that tend to be highly sensitive to the choice of state space basis.     

一种新的虹膜定位方法

针对现有虹膜定位算法的局限性,提出了一种新的虹膜定位的方法.先对虹膜图像进行预处理,用canny边缘检测算子检测得到虹膜内边缘;再通过二次canny边缘检测对虹膜外边缘进行粗定位,然后分小区域对虹膜外边缘实现多阈值边缘检测,从而获得真实边缘,再利用虹膜内外边缘之间的耦合关系,结合最小二乘法实现虹膜外边缘的定位.实验结果表明,此方法能比较快速准确地定位出虹膜的内外边缘.     

一种改进型免疫算法在TDOA定位中的应用

为解决传统TDOA定位估计所带来的非线性优化问题,首先通过最大似然估计将其转换为峰值搜索优化问题,再提出一种基于克隆选择思想的改进型免疫算法对其进行求解。该算法采用浮点数编码方式,提高了运算效率;引入高斯变异算子和变异控制变量,加强了局部搜索能力。仿真实验表明,在保证一定抗体数目的前提下,该算法适应性强,性能稳定,能快速逼近全局最优的解,且算法定位精度更高。     

Transient performance analysis in robust nonlinear adaptive control

This paper deals with the problem of controlling unknown linear systems in the presence of strictly proper unmodelled dynamics and bounded disturbances. Adaptive controllers that ensure the closed-loop global (uniform) stability and asymptotic performances can be designed following either the backstepping approach or the certainty-equivalence method. The main shortcoming of the involved controllers is that they do not allow quantification of the closed-loop transient behaviour. In this paper, the transient issue is addressed for backstepping adaptive controllers. A L_∞ bound on the tracking error is explicitly given as a function of the design parameters. This shows that the error can be made arbitrarily small by sufficiently increasing the design gains.     

A method for particle location and field interpolation on complex, three-dimensional computational meshes

A method for locating particles within arbitrary three-dimensional computational meshes is described. It is based on an iterative procedure which uses transformed coordinates defined by iso-parametric functions. The method also enables one to interpolate field values from the mesh nodes to the particle position. Example applications demonstrate how effective the method is. For very distorted computational cells special practices have to be introduced in order to keep the number of iterations to a minimum.     

A new method to evaluate human-robot system performance

One of the key issues in space exploration is that of deciding what space tasks are best done with humans, with robots, or a suitable combination of each. In general, human and robot skills are complementary. Humans provide as yet unmatched capabilities to perceive, think, and act when faced with anomalies and unforeseen events, but there can be huge potential risks to human safety in getting these benefits. Robots provide complementary skills in being able to work in extremely risky environments, but their ability to perceive, think, and act by themselves is currently not error-free, although these capabilities are continually improving with the emergence of new technologies. Substantial past experience validates these generally qualitative notions. However, there is a need for more rigorously systematic evaluation of human and robot roles, in order to optimize the design and performance of human-robot system architectures using well-defined performance evaluation metrics. This article summarizes a new analytical method to conduct such quantitative evaluations. While the article focuses on evaluating human-robot systems, the method is generally applicable to a much broader class of systems whose performance needs to be evaluated.     

Nonlinear robust performance analysis using complex-step gradient approximation

In this paper, the complex-step method is applied in the setting of numerical optimisation problems involving dynamical systems modelled as nonlinear differential equations. The main advantage of the complex-step method for gradient approximation is that it entails no subtractive cancellation error, and therefore the truncation error can be made arbitrarily (to machine precision) small. The method is applied to two robust performance analysis problems. The accuracy and convergence rate of the solutions computed using the proposed approach are seen to be significantly better than those achieved using standard gradient approximation methods.     

A probabilistic model for performance analysis of cloud infrastructures

Analyzing the quantitative performance plays an important role in understanding and improving the quality of cloud computing systems and cloud‐based applications. In cloud computing, service requests from users go through numerous provider‐specific steps from the instant it is submitted to when the requested service is fully delivered. Quantitative performance analysis is not an easy task because of the complexity of cloud provisioning control flows and the increasing scale and complexity of real‐world cloud infrastructures. This work proposes a probabilistic queuing network‐based model for the performance analysis of cloud infrastructures. It considers expected task completion time and rejection probability as the performance metrics. Experimental performance data suggest the correctness of the proposed model. Copyright © 2015 John Wiley & Sons, Ltd.     

改进的鲁棒总体最小二乘无源定位算法

针对机载无源定位易受异常误差影响的问题,提出一种基于角度信息的鲁棒递推总体最小二乘定位（RRTLS）算法。建立机载无源定位模型,得出总体最小二乘（TLS）解,根据机载定位的实时性、低复杂度要求将其转化为加权递推形式;根据广义M估计原理构建鲁棒TLS极值准则,利用其性质将RRTLS定位问题转化为等价权函数的设计问题;验证了利用残差识别异常误差的合理性,在此基础上建立了等价权函数。仿真结果表明,不存在异常误差时,递推总体最小二乘（RTLS）算法和RRTLS算法均能较好收敛;存在异常误差时,递推最小二乘（RLS）和RTLS定位结果受到扭曲,而RRTLS算法能够获得理想的估值,具有较强的鲁棒性。     

WSN中基于Robust Position节点定位算法改进的研究

节点定位一直是无线传感器网络研究的热点之一。由于不同应用系统对节点的定位精度有着不同的要求,因此目前并不存在最优的节点定位算法。首先深入分析了具有代表性的两种分布式的节点定位算法,并从定位精度及能量消耗两个方面给出了定量分析结果。在此基础上提出了改进的定位算法:BB_RP算法,通过仿真实验,在定位精度和能量消耗两个方面与原有算法进行定量的分析比较。结果表明,BB_RP算法虽然在定位精度略低于原有的算法,但是在能量消耗和覆盖速度两个指标上有了较大的提高,使得无线传感器网络的生命周期延长。     

分析语句命中谱的自动故障定位方法研究

软件故障的自动定位能提高测试过程的效率,对改善软件的可信性也相当重要。在原有程序谱分析故障定位基础上,提出了基于语句命中谱分析的自动故障定位方法,通过引进聚类函数克服了基于模型的故障定位计算量过大的问题,并和现有的程序谱定位工具Pinpoint、Tarantula进行了比较,最终通过实验证明了这种方法的高效性和优越性。     

基于硬件性能计数器的软件性能数据采集与分析研究

引入了基于CPU硬件性能计数器的性能数据采集和分析方法，从软件运行时刻的细粒度参数入手分析软件运行时刻的性能表现，从而更为准确地反映系统实际的动态运行状态。实验证明，这种方法对于需要详细掌握系统动态运行状态的应用能够提供非常有效的分析数据，同时也在一定程度上对编译器的性能优化给出了相关参考数据。     

无线传感器网络中一种模糊加权目标定位方法

提出了一种无线传感器网络( WSNs)中的模糊加权定位算法,利用探测节点RSSl值的估计距离为平面离散栅格分配权值,通过比较累计权值搜索出目标坐标,其模糊性使得该方法能够有效地抵抗各种强度的噪声,设定可调模糊度适应不同的衰落信道,在单目标定位中具有非常高的稳定性.针对多目标定位,提出变型的权值模型,设计了去模糊化算法将多个目标坐标提取出来.对实验仿真结果作出了评估,并提出了多目标定位的限制条件.     

确保鲁棒性能的PID控制器参数域的一种确定方法

研究了将混合灵敏度的H∞范数作为PID控制器的鲁棒设计指标时,控制器参数的可行域确定问题．首先将混合灵敏度的H∞范数要求转化为一族复系数多项式的稳定性要求,再加上基本闭环特征多项式的稳定性,通过求解这些含参数多项式的稳定性,解出参数的可行域．在求解多项式稳定性的过程中,采用了推广的Hermite—Biehler定理．