Modified criterion for global asymptotic stability of fixed-point state-space digital filters using two’s complement arithmetic

A criterion for the global asymptotic stability of fixed-point state-space digital filters using two’s complement arithmetic is presented. The criterion is a modified form of a well-known criterion due to Mills, Mullis, and Roberts. The criterion is in the form of linear matrix inequality and, hence, computationally tractable. An example shows the effectiveness of the modified criterion.     

Improved passivity criterion in haptic rendering: influence of Coulomb and viscous friction

In this paper, a new criterion for passivity of haptic devices is obtained. This criterion creates a relationship between Coulomb friction coefficient, viscous friction coefficient, sampling rate, and the maximum simulated stiffness. The process of derivation of the passivity criterion is described in detail. This criterion is improved compared with other existing criteria and predicts passivity in haptic rendering more accurately. In particular, for speeds of less than 5?cm/s, the new passivity criterion should replace the previous criteria to avoid unwanted vibrations of stiff virtual walls. Analytical and numerical investigations are presented to validate the new criterion. A specific trajectory is designed and the movement of the haptic robot is investigated on this trajectory to validate and compare this passivity criterion with the previous criteria.     

Elimination of overflow oscillations in fixed-point state-space digital filters using saturation arithmetic: An LMI approach

A criterion for the nonexistence of overflow oscillations in fixed-point state-space digital filters employing saturation arithmetic is presented. The criterion possesses the structure of linear matrix inequality and hence is computationally tractable. The criterion is compared with an earlier LMI-based criterion.     

Gradient-based optimization of hyperparameters

Many machine learning algorithms can be formulated as the minimization of a training criterion that involves a hyperparameter. This hyperparameter is usually chosen by trial and error with a model selection criterion. In this article we present a methodology to optimize several hyperparameters, based on the computation of the gradient of a model selection criterion with respect to the hyperparameters. In the case of a quadratic training criterion, the gradient of the selection criterion with respect to the hyperparameters is efficiently computed by backpropagating through a Cholesky decomposition. In the more general case, we show that the implicit function theorem can be used to derive a formula for the hyperparameter gradient involving second derivatives of the training criterion.     

Performance criterion of neural networks learning

The article deals with a new criterion (the wave criterion) of estimating the generalizing ability of a neural network. The theoretical grounding of the criterion is based on Bayes theorem, the methods of cybernetics and synergy. The computing experiments carried out with the databases Fmtrain, Matt, Grng, Ada have proved the criterion to be an effective tool.     

多输出布尔函数的k阶严格雪崩准则

首次将k阶严格雪崩准则的概念扩展到多输出布尔函数上,首先研究了多输出函数的严格雪崩准则、扩散准则,给出了多输出函数满足k阶严格雪崩准则的两个充分必要条件,证明了多输出布尔函数满足高阶严格雪崩准则时一定满足低阶严格雪崩准则。然后根据对称函数的特性,应用数论的知识,研究了多输出对称布尔函数的严格雪崩准则、扩散准则和k阶严格雪崩性质,给出了相应准则的充分必要条件,特别给出了两个k阶严格雪崩准则的组合判别公式。     

Feature selection for best mean square approximation of class densities

A criterion for feature selection is proposed which is based on mean square approximation of class density functions. It is shown that for the widest possible class of approximants, the criterion reduces to Devijer's Bayesian distance. For linear approximants the criterion is equivalent to well known generalized Fisher criteria.     

约束条件帧间差值运动估值匹配准则

运动估值是视频压缩编码的核心E针对块匹配算法中广泛采用的MAD准则的不足,提出了一种约束条 件帧间差值运动估值匹配准则,通过理论分析和实验比较,证实了新匹配准则的优越性.     

一类基于多目标规划的线性鉴别准则

两类Fisher鉴别准则、大间距线性投影准则以及最大散度差鉴别准则都是直接用于模式分类的两类线性鉴别准则,它们的共同点是将“投影后数据的可分性达到最大的方向”作为最优投影方向。区别在于它们对数据可分性的定义有所不同。过去的研究成果表明,大间距线性投影分类器与支持向量机之间、大间距线性投影准则与最大散度差鉴别准则之间以及最大散度差鉴别准则与两类Fisher鉴别准则之间,均存在着这样或那样的联系。论文试图在以往研究成果的基础上进一步理清这些两类线性鉴别准则之间的内在关系,并建立一个统一的理论框架从而将基于投影后数据可分性的这些两类线性鉴别准则都纳入其中。     

An improved criterion for the global asymptotic stability of fixed-point state-space digital filters with saturation arithmetic

A criterion for the global asymptotic stability of fixed-point state-space digital filters with saturation arithmetic is presented. The criterion makes use of the structural properties of the multiple saturation nonlinearities in greater detail than several existing criteria. The relationship between the presented criterion and some existing ones is established. Through the relationship, it is clear that the presented criterion is less conservative than corresponding existing results, which is confirmed by a numerical example.     

Selection of generative models in classification

This paper is concerned with the selection of a generative model for supervised classification. Classical criteria for model selection assess the fit of a model rather than its ability to produce a low classification error rate. A new criterion, the Bayesian entropy criterion (BEC), is proposed. This criterion takes into account the decisional purpose of a model by minimizing the integrated classification entropy. It provides an interesting alternative to the cross-validated error rate which is computationally expensive. The asymptotic behavior of the BEC criterion is presented. Numerical experiments on both simulated and real data sets show that BEC performs better than the BIC criterion to select a model minimizing the classification error rate and provides analogous performance to the cross-validated error rate.     

一种新的内禀模态函数判据

针对现有EMD（Empirical Mode Decomposition）分解过程中内禀模态函数判据必须确定某一经验值的缺点,本文提出了一种基于信息熵的内禀模态函数判据,该判据不必设定某一参数的经验值,从而避免了由于经验取值不同造成分解结果有很大差异的缺陷. 通过与现有方法的对比表明：依此判据所得内禀模态函数更准确,能够很好的体现信号的非线性、非平稳特征,同时使分解结果具有更好的正交性. 将此判据应用在风力发电机组齿轮箱高速端轴承的故障诊断中,验证了依此判据所得分解结果更好的保留了冲击脉冲、幅值和频率调制等故障特征信息,从而准确诊断出故障部位所在.     

A multivariable extension of the Tsypkin criterion using aLyapunov-function approach

For analyzing the stability of discrete-time systems containing a feedback nonlinearity, the Tsypkin criterion is the closest analog to the Popov criterion which is used for analyzing such systems in continuous time. Traditionally, the proof of this criterion is based upon input-output properties and function analytic methods. In this paper we extend the Tsypkin criterion to multivariable systems containing an arbitrary number of monotonic sector-bounded memoryless time-invariant nonlinearities, along with providing a Lyapunov function proof for this classical result     

满足k次强扩散准则的布尔函数谱特征分析

利用概率方法和频谱理论,给出布尔函数满足强扩散准则的一个新的等价判别条件,并根据强扩散准则与扩散准则之间的关系,得到满足k次强扩散准则的布尔函数的2种构造方法。结合具有平衡性和相关免疫性的布尔函数的谱特征,给出缸欺骗免疫秘密共享定义函数的谱判别条件。     

Modernization of one criterion for absolute stability

A new form of a partial frequency criterion of absolute stability for nonlinear automatic control systems is obtained basing on a quadratic transformation of the state vector. As is shown, the obtained criterion is stronger than V.M. Popov’s one. An alternative formulation of the criterion is given in terms excluding the notions of quadratic transformation.     

任意范数熵与特征抽取

文章概述了各种用于特征抽取的可分性准则的概况。介绍了按任意范数熵定义的可分性准则,分析并证明了这一准则的一些性质,同时介绍了一种定量比较各种准则的方法。按此方法对现有主要准则作了定量比较,计算结果说明任意范数下的熵准则是一种非常有效的可分性准则。     

Optimization formulations for the maximum nonlinear buckling load of composite structures

This paper focuses on criterion functions for gradient based optimization of the buckling load of laminated composite structures considering different types of buckling behaviour. A local criterion is developed, and is, together with a range of local and global criterion functions from literature, benchmarked on a number of numerical examples of laminated composite structures for the maximization of the buckling load considering fiber angle design variables. The optimization formulations are based on either linear or geometrically nonlinear analysis and formulated as mathematical programming problems solved using gradient based techniques. The developed local criterion is formulated such it captures nonlinear effects upon loading and proves useful for both analysis purposes and as a criterion for use in nonlinear buckling optimization.     

软件测试准则的有效性度量研究

测试准则的有效性是软件质量保障的一个重要问题，但至今仍没有一个有效的度量方法．已有的度量对于全面表示测试效果、提高软件质量的作用非常有限．潜在失效距离（pfd）将测试准则对软件的测试有效性视为以规范、程序、缺陷类型和测试准则为自变量的函数，从软件和测试准则交互的角度来度量测试的有效性．与已有的度量相比较，该度量反映了软件经过满足测试准则的充分测试后获得的可靠性，为比较测试准则的测试效果提供了可行的方法，为设计更易测试的软件提供了指标．     

字典序下BMS算法终止条件的设计

编码理论中的BMS算法具有良好的解码效率与纠错能力,目前的研究通常集中于分次项序下的情形。通过分析字典序与分次项序的本质特征,利用与BMS算法密切相关的Gr?bner基的消去性质,设计出字典序下BMS算法的终止条件,并给出了基于该条件的易于实现的具体算法描述。实验结果表明,该终止条件切实有效,与算法中的原始理论终止条件完全吻合。     

A new method for failure prediction of SR-200 beryllium sheet structures

Contemporary applications of failure criteria frequently incorporate two-dimensional or simplified three-dimensional methodologies for prediction of failure stresses. Motivation behind the development of a new multi-dimensional failure criterion is due mainly to the lack of a sufficiently accurate mathematical tool that accounts for the behavior of brittle material with anisotropic properties. Such a criterion should be able to provide a reliable maximum load estimate so that design of the structure is not penalized in terms of excessive weight requirements. The failure criterion developed is represented by a fracture surface in a six-dimensional stress space. The criterion is applied for failure prediction of SR-200 beryllium sheet structures, a non-homogeneous orthotropic material used widely in space applications. Two experiments are used to verify the criterion.