设计有限字长FIR数字滤波器的蚂蚁算法

蚂蚁算法(AA)是一种模拟蚂蚁觅食时建立蚁巢到食物最短路径的新型启发式优化算法.本文通过改进蚂蚁算法,取消了蚂蚁算法原型的禁忌表,将其应用于有限字长FIR数字滤波器的优化设计,并在最小最大(MM)、最小平方(LS)和纹波约束最小平方(PCLS)优化准则下,在通带和阻带施加适当的约束条件,建立相应的优化模型,给出了设计的详细实现步骤.该算法不仅程序实现简单,而且具有通用性强、本质并行的优点.仿真结果表明了该算法的优越性和通用性.     

基于改进型Hopfield神经网络的盲多用户检测算法

基于Hopfield神经网络没有学习规则,不需要训练,也不会自学习,靠Lyapunov函数的设计过程来调节权值的特点,将广义罚函数与Hopfield神经网络的能量函数结合,基于最小平均输出能量准则,构造出更合适的新目标函数,分析讨论了一种实现DS/CDMA盲多用户检测的改进型Hopfield神经网络方法。仿真结果表明,该算法在误码率、抗远近效应方面都有明显的改善。     

一种小波神经网络的在线建模和校正算法

提出应用小波神经网络实现非线性系统模型的在线建立及自校正方法.首先提出了小波网络节点库的构成方法和一种小波网络模型结构确定和权值估计方法.在此基础上运用限定记忆最小二乘法,设计小波网络自学习建模和在线校正的算法.该算法能根据系统输入输出数据自动地建立小波网络模型,并使得在线校正得到的小波神经网络在某种准则下是最优的.     

神经网络在线投影算法及非线性建模应用

针对神经网络难以在线学习的缺点,把神经网络当作结构已知的非线性系统,权系数的学习看成非线性系统的参数估计,基于新估计准则的非线性系统在线参数估计投影算法,给出前馈神经网络的一种在线运行投影学习算法.理论上证明该算法的全局收敛性,讨论算法参数的物理意义和取值范围.通过2个非线性时变系统的神经网络建模应用的仿真,验证算法的全局收敛性和在线运行能力.     

基于RBF神经网络的产品概念设计方案评价

分析了现有评价方法存在的问题,利用Matlab神经网络工具箱构建了RBF网络模型,并以冰箱为实例进行评价.RBF神经网络采用监督学习算法和正交最小平方(OLS)算法决定基函数的中心、方差以及隐含层到输出层的权值.与BP神经网络模型的评价结果对比,建立的RBF神经网络评价模型具有更高的预测精度,收敛速度更快.     

Lagrange优化前馈神经网络盲多用户检测算法

提出了一种前馈神经网络盲多用户检测算法.该算法利用恒模准则构造了一个代价函数,给出了该算法的约束条件.利用增广Lagrange函数方法对带约束的代价函数进行优化求解,获得前馈神经网络网络权值和参数的迭代公式,从而实现了盲多用户检测.利用计算机对增广Lagrange函数优化的前馈神经网络盲多用户检测算法进行仿真.仿真结果表明,新算法具有较好的误码率及收敛特性等性能.     

基于粗糙集理论的RBF神经网络剪枝算法

分析了满足给定学习误差要求的最小结构神经网络的各种实现方法.把粗糙集理论引入神经网络的结构构造中;提出了一种基于粗糙集理论的RBF神经网络剪枝算法,并将这种算法与现有剪枝算法相比较.最后将该算法应用于热工过程中过热气温动态特性建模.仿真结果表明基于该算法的神经网络模型具有较高的建模精度以及泛化能力.     

基于约束反赫布算法的自适应二维FIR滤波器实现

提出了一种用神经网络来实现自适应二维FIR滤波器的新方法,主要是运用约束反赫布学习算法,训练一个神经网络,实现了基于TLS准则的自适应二维FIR滤波器,计算机仿真结果表明该滤波器在收敛性能和精度上均优于基于LMS准则的自适应二维FIR滤波器。     

基于神经网络的MIMO-OFDM信道估计

提出了一种适用于神经网络框架下的MIMO-OFDM系统的信道估计算法。通过对三层神经网络结构的分析,用两层神经网络实现了一种主成分分析（PCA）最小二乘学习算法。通过导频信息得到MIMO-OFDM信道模型初始值,再用神经网络算法对MIMO-OFDM信道的时变状态参数进行跟踪;采用两层神经网络,由隐层输出对最终输出修正,中间实现可变遗忘因子的改进递推最小二乘学习算法。仿真结果表明,该方法与最小二乘（LS）算法相比,在跟踪时变衰落信道时,估计的均方误差有较大提高,从而有效地改善了接收端的符号检测性。     

一种改进BP神经网络的算法

传统的神经网络BP算法存在收敛速度慢、存在局部极小点等问题,这种算法收敛慢的主要原因是它利用的是性能函数的一阶信息,递推最小二乘算法利用了二阶信息,但是需要计算输入信号的自相关矩阵的逆,计算量大,不易实现。本文提出一种梯度递推BP算法,它基于最小二乘准则,利用改进的梯度来实现BP算法,这种算法不用计算输入信号的自相关矩阵,并通过仿真证明了该算法的有效性。     

基于密度核估计的贝叶斯网络结构学习算法

贝叶斯网络结构学习算法主要包括爬山法和K2算法等,但这些方法均要求面向大样本数据集。针对实际问题中样本集规模小的特点,通过引入概率密度核估计方法以实现对原始样本集的拓展,利用K2算法进行贝叶斯网络结构学习。通过优化选择核函数和窗宽,基于密度核估计方法实现了样本集的有效扩展;同时基于互信息度进行变量顺序的确认,进而建立了小规模样本集的贝叶斯结构学习算法。仿真结果验证了新学习算法的有效性和实用性。     

Risk-Sensitive Reinforcement Learning

Most reinforcement learning algorithms optimize the expected return of a Markov Decision Problem. Practice has taught us the lesson that this criterion is not always the most suitable because many applications require robust control strategies which also take into account the variance of the return. Classical control literature provides several techniques to deal with risk-sensitive optimization goals like the so-called worst-case optimality criterion exclusively focusing on risk-avoiding policies or classical risk-sensitive control, which transforms the returns by exponential utility functions. While the first approach is typically too restrictive, the latter suffers from the absence of an obvious way to design a corresponding model-free reinforcement learning algorithm.Our risk-sensitive reinforcement learning algorithm is based on a very different philosophy. Instead of transforming the return of the process, we transform the temporal differences during learning. While our approach reflects important properties of the classical exponential utility framework, we avoid its serious drawbacks for learning. Based on an extended set of optimality equations we are able to formulate risk-sensitive versions of various well-known reinforcement learning algorithms which converge with probability one under the usual conditions.     

A sequential multi-category classifier using radial basis function networks

This paper presents a new sequential multi-category classifier using radial basis function (SMC-RBF) network for real-world classification problems. The classification algorithm processes the training data one by one and builds the RBF network starting with zero hidden neuron. The growth criterion uses the misclassification error, the approximation error to the true decision boundary and a distance measure between the current sample and the nearest neuron belonging to the same class. SMC-RBF uses the hinge loss function (instead of the mean square loss function) for a more accurate estimate of the posterior probability. For network parameter updates, a decoupled extended Kalman filter is used to reduce the computational overhead. Performance of the proposed algorithm is evaluated using three benchmark problems, viz., image segmentation, vehicle and glass from the UCI machine learning repository. In addition, performance comparison has also been done on two real-world problems in the areas of remote sensing and bio-informatics. The performance of the proposed SMC-RBF classifier is also compared with the other RBF sequential learning algorithms like MRAN, GAP-RBFN, OS-ELM and the well-known batch classification algorithm SVM. The results indicate that SMC-RBF produces a higher classification accuracy with a more compact network. Also, the study indicates that using a function approximation algorithm for classification problems may not work well when the classes are not well separated and the training data is not uniformly distributed among the classes.     

基于最大类间后验交叉熵的阈值化分割算法

从目标和背景的类间差异性出发,提出了一种基于最大类间交叉熵准则的阈值化分割新算法。该算法假设目标和背景象素的条件分布服从正态分布,利用贝叶斯公式估计象素属于目标和背景两类区域的后验概率,再搜索这两类区域后验概率之间的最大交叉熵。比较了新算法与基于最小交叉熵以及基于传统香农熵的阈值化算法的特点和分割性能。     

基于最大类间后验交叉熵的阈值比分割算法

从目标和背景的类间差异性出发,提出了一种基于最大类间交叉熵准则的阈值化分割新算法,算法阈设目标的背景象素的条件分布服从正态分布,利用贝叶期公式估计象素属于目标和背景两类区域的后验概率,再搜索这两为区域后验概率之间的最大交叉熵。比较了新算法一基于最小交叉熵以及基于传统香农熵的阈值化算法的分割性能。     

基于多点加点准则的代理模型辅助社会学习微粒群算法

代理模型辅助的进化算法目前已广泛用于解决计算代价高的复杂优化问题.然而,大多数现有的代理辅助进化算法只适用于低维问题且仍然需要数千次昂贵的真实适应值评价来获得较优解.为此,提出一种基于多点加点准则的代理模型辅助的社会学习微粒群算法,用于解决高维问题并使用更少的评价次数.该算法选用高斯过程构造代理模型,以社会学习微粒群算法(SLPSO)作为优化器,提出一种基于相似度的多点加点规则(SMIC),用于选取需要使用原函数进行实际计算的候选解.在仿真实验中将该方法与现有研究成果进行比较,通过对50维sim100维的基准函数的测试,验证了所提出算法在有限的适应值计算次数下拥有更好的寻优性能,尤其是在高维优化问题上拥有更显著的优势.     

PBIL算法在组合优化问题中的应用研究

基于群体的增量学习(PBIL)算法有效结合了遗传算法和竞争学习的优点,运行过程简单,解决问题快速准确。本文提出将PBIL算法应用于求解CMN组合优化问题,以物流中心选址优化问题为例,介绍了基于PBIL求解CMN组合优化问题的一般方法,提出了针对此类问题的个体产生算法。为了提高算法的收敛速度和寻优能力,提出了基于当代最优解与历代最优解比较结果的概率学习加速方法。最后,通过实验仿真验证了上述改进的有效性。     

A learning automata-based algorithm for determination of the number of hidden units for three-layer neural networks

There is no method to determine the optimal topology for multi-layer neural networks for a given problem. Usually the designer selects a topology for the network and then trains it. Since determination of the optimal topology of neural networks belongs to class of NP-hard problems, most of the existing algorithms for determination of the topology are approximate. These algorithms could be classified into four main groups: pruning algorithms, constructive algorithms, hybrid algorithms and evolutionary algorithms. These algorithms can produce near optimal solutions. Most of these algorithms use hill-climbing method and may be stuck at local minima. In this article, we first introduce a learning automaton and study its behaviour and then present an algorithm based on the proposed learning automaton, called survival algorithm, for determination of the number of hidden units of three layers neural networks. The survival algorithm uses learning automata as a global search method to increase the probability of obtaining the optimal topology. The algorithm considers the problem of optimization of the topology of neural networks as object partitioning rather than searching or parameter optimization as in existing algorithms. In survival algorithm, the training begins with a large network, and then by adding and deleting hidden units, a near optimal topology will be obtained. The algorithm has been tested on a number of problems and shown through simulations that networks generated are near optimal.     

Implementing online natural gradient learning: problems and solutions

The online natural gradient learning is an efficient algorithm to resolve the slow learning speed and poor performance of the standard gradient descent method. However, there are several problems to implement this algorithm. In this paper, we proposed a new algorithm to solve these problems and then compared the new algorithm with other known algorithms for online learning, including Almeida-Langlois-Amaral-Plakhov algorithm (ALAP), Vario-/spl eta/, local adaptive learning rate and learning with momentum etc., using sample data sets from Proben1 and normalized handwritten digits, automatically scanned from envelopes by the U.S. Postal Services. The strong and weak points of these algorithms were analyzed and tested empirically. We found out that using the online training error as the criterion to determine whether the learning rate should be changed or not is not appropriate and our new algorithm has better performance than other existing online algorithms.     

求解动态优化问题的多种群热力学遗传算法

多种群方法已被证明是提高演化算法动态优化性能的重要方法之一。提出了多种群热力学遗传算法（multi-population based thermodynamic genetic algorithm,MPTDGA）。该算法使用一个概率向量在热力学遗传算法迭代过程中不断演化优化与竞争学习,环境变化时分化成三个概率向量,并分别抽样产生原对偶和随机迁入三个子种群,依据这三个种群和记忆种群最好解的情况,选择新的工作概率向量进入新环境进行学习。在动态背包问题上的实验结果表明,MPTDGA比原对偶遗传算法跟踪最优解的能力更强,有很好的多样性,非常适合求解0-1动态优化问题。