具有双储层结构的动态误差补偿回声状态网络

针对传统回声状态网络难以有效应对高阶非线性复杂模型问题,本文在理论分析的基础上提出了一种双储层结构的误差补偿回声状态网络,并设计了该网络的学习算法.该网络由计算层和补偿层构成,计算层主要承担拟合任务,补偿层则作为状态跟随器,实时补偿由于计算层对期望方差估计不足而导致的幅值偏差.对多阶振荡器和真实高阶非线性数据集的实验结果表明,本文所提网络结构较常规网络具有更高的稳定性和泛化性能,尤其对高阶非线性复杂模型的预测精度大幅度提升.     

Fate and free will in error traces

The ability to generate counterexamples for failing properties is often cited as one of the strengths of model checking. However, it is often difficult to interpret long error traces in which many variables appear. Besides, a traditional error trace presents only one possible behavior of the system causing the failure, with no further annotation. Our objective is to identify some structure in the error trace to make debugging easier. We present an enhanced error trace as an alternation of fated (forced) and free segments. The fated segments show unavoidable progress toward the error while the free segments show choices that, if avoided, may have prevented the error. Hence, the demarcation into segments tends to highlight critical events. The segmentation of a trace raises the questions of whether the fated segment should indeed be inevitable and whether the free segments are critical in causing the error. Addressing these questions may help the user to better analyze the failure of the property.     

TRAP:trace runtime analysis of properties

We present a method and a tool for the verification of causal and temporal properties for embedded systems.We analyze trace streams resulting from the execution of virtual prototypes that combine simulated hardware and embedded software.The main originality lies in the use of logical clocks to abstract away irrelevant information from the trace.We propose a model-based approach that relies on domain specific languages(DSL).A first DSL,called TISL(trace item specification language),captures the relevant data structures.A second DSL,called STML(simulation trace mapping language),abstracts the simulation raw data into logical clocks,abstracting simulation data into relevant observation probes and thus reducing the trace streams size.The third DSL,called TPSL,defines a set of behavioral patterns that include widely used temporal properties.This is meant for users who are not familiar with temporal logics.Each pattern is transformed into an automata.All the automata are executed concurrently and each one raises an error if and when the related TPSL property is violated.The contribution is the integration of this pattern-based property specification language into the SimSoC virtual prototyping framework without requiring to recompile all the simulation models when the properties evolve.We illustrate our approach with experiments that show the possibility to use multi-core platforms to parallelize the simulation and verification processes,thus reducing the verification time.     

Adaptive error control for multigrid finite element

We consider the problem of adaptive error control in the finite element method including the error resulting from, inexact solution of the discrete equations. We prove a posteriori error estimates for a prototype elliptic model problem discretized by the finite element with a canomical multigrid algorithm. The proofs are based on a combination of so-called strong stability and, the orthogonality inherent in both the finite element method can the multigrid algorithm.     

An Expressively Complete Linear Time Temporal Logic for Mazurkiewicz Traces

A basic result concerning LTL, the propositional temporal logic of linear time, is that it is expressively complete; it is equal in expressive power to the first order theory of sequences. We present here a smooth extension of this result to the class of partial orders known as Mazurkiewicz traces. These partial orders arise in a variety of contexts in concurrency theory and they provide the conceptual basis for many of the partial order reduction methods that have been developed in connection with LTL-specifications.We show that LTrL, our linear time temporal logic, is equal in expressive power to the first order theory of traces when interpreted over (finite and) infinite traces. This result fills a prominent gap in the existing logical theory of infinite traces. LTrL also constitutes a characterisation of the so-called trace consistent (robust) LTL-specifications. These are specifications expressed as LTL formulas that do not distinguish between different linearisations of the same trace and hence are amenable to partial order reduction methods.     

A Posteriori Error Estimates for Parabolic Variational Inequalities

We study a posteriori error estimates in the energy norm for some parabolic obstacle problems discretized with a Euler implicit time scheme combined with a finite element spatial approximation. We discuss the reliability and efficiency of the error indicators, as well as their localization properties. Apart from the obstacle resolution, the error indicators vanish in the so-called full contact set. The case when the obstacle is piecewise affine is studied before the general case. Numerical examples are given.     

Characterizations of the decidability of some problems for regular trace languages

The decidability of the equivalence problem and the disjointness problem for regular trace languages is considered. By describing the structure of the independence relations involved, precise characterizations are given of those concurrency alphabets for which these problems are decidable. In fact, the first problem is decidable if and only if the independence relation is transitive, while the second problem is decidable if and only if the independence relation is a so-called transitive forest.     

Classical Electromagnetic Potential as a Part of Gravitational Connection: Ideas and History

We consider a natural form of a unified theory of gravity and electromagnetism which was somehow missed at the time of intense search for such a unification. The basic idea of this unification is to use the symmetric metric and a non-symmetric connection as independent variables, which generalizes the so-called Palatini formalism. For the first time this idea was applied to the construction of the action for a unified theory of gravity and electromagnetism without matter only in 1978, but this result did not receive wide recognition. In this paper we propose a natural way to include matter in the form of classical particles into the unified theory. The trace of connection in the appearing theory can be naturally identified with the electromagnetic potential, and the Einstein-Maxwell equations with classical matter are reproduced. We compare this approach with the known ideas of unification and briefly discuss the perspectives of a further development of this approach.     

Automated Trace Analysis of Discrete-Event System Models

In this paper, we describe a novel technique that helps a modeler gain insight into the dynamic behavior of a complex stochastic discrete event simulation model based on trace analysis. We propose algorithms to distinguish progressive from repetitive behavior in a trace and to extract a minimal progressive fragment of a trace. The implied combinatorial optimization problem for trace reduction is solved in linear time with dynamic programming. We present and compare several approximate and one exact solution method. Information on the reduction operation as well as the reduced trace itself helps a modeler to recognize the presence of certain errors and to identify their cause. We track down a subtle modeling error in a dependability model of a multi-class server system to illustrate the effectiveness of our approach in revealing the cause of an observed effect. The proposed technique has been implemented and integrated in Traviando, a trace analyzer to debug stochastic simulation models.     

FD-ZKF: A Zonotopic Kalman Filter optimizing fault detection rather than state estimation

Enhancing the sensitivity to faults with respect to disturbances, rather than optimizing the precision of the state estimation using Kalman Filters (KF) is the subject of this paper. The stochastic paradigm (KF) is based on minimizing the trace of the state estimation error covariance. In the context of the bounded-error paradigm using Zonotopic Kalman Filters (ZKF), this is analog to minimize the covariation trace. From this analogy and keeping a similar observer-based structure as in ZKF, a criterion jointly inspired by set-membership approaches and approximate decoupling techniques coming from parity-space residual generation is proposed. Its on-line maximization provides an optimal time-varying observer gain leading to the so-called FD-ZKF filter that allows enhancing the fault detection properties. The characterization of minimum detectable fault magnitude is done based on a sensitivity analysis. The effect of the uncertainty is addressed using a set-membership approach and a zonotopic representation reducing set operations to simple matrix calculations. A case study based on a quadruple-tank system is used both to illustrate and compare the effectiveness of the results obtained from the FD-ZKF approach compared to a pure ZKF approach.     

Glasses removal from facial image using recursive error compensation

In this paper, we propose a new method of removing glasses from a human frontal facial image. We first detect the regions occluded by the glasses and generate a natural looking facial image without glasses by recursive error compensation using PCA reconstruction. The resulting image has no trace of the glasses frame or of the reflection and shade caused by the glasses. The experimental results show that the proposed method provides an effective solution to the problem of glasses occlusion and we believe that this method can also be used to enhance the performance of face recognition systems.     

基于迹比准则与+L-R方法的特征选择算法

提出一种将迹比准则和基于错分区域的+L-R方法相结合的特征选择算法.该算法使用迹比算法得到优秀特征子集,对分类产生的错分区域进行+L-R选择得到新特征,新特征可以区分之前被错分的数据,从而降低错分率.采用+L-R算法降低数据冗余.实验结果表明,该算法有效改进迹比准则特征选择算法,同时降低错分率.     

Near optimal interval observers bundle for uncertain bioreactors

In this paper we design an interval observer for the estimation of unmeasured variables of uncertain bioreactors. The observer is based on a bounded error observer, as proposed in [Lemesle, V., & Gouzé, J.-L. (2005). Hybrid bounded error observers for uncertain bioreactor models. Bioprocess and Biosystems Engineering, 27, 311-318], that makes use of a loose approximation of the bacterial kinetics. We first show how to generate guaranteed upper and lower bounds on the state, provided that known intervals for the initial condition and the uncertainties are available. These so-called framers depend on a tuning gain. They can be run in parallel and the envelope provides the best estimate. An optimality criterion is introduced leading to the definition of an optimal observer. We show that this criterion provides directly a gain set containing the best framers. The method is applied to the estimation of the total biomass of an industrial wastewater treatment plant, demonstrating its efficiency.     

Goal-oriented error estimation and adaptivity for the finite element method

In this paper, we study a new approach in a posteriori error estimation, in which the numerical error of finite element approximations is estimated in terms of quantities of interest rather than the classical energy norm. These so-called quantities of interest are characterized by linear functionals on the space of functions to where the solution belongs. We present here the theory with respect to a class of elliptic boundary-value problems, and in particular, show how to obtain accurate estimates as well as upper and lower bounds on the error. We also study the new concept of goal-oriented adaptivity, which embodies mesh adaptation procedures designed to control error in specific quantities. Numerical experiments confirm that such procedures greatly accelerate the attainment of local features of the solution to preset accuracies as compared to traditional adaptive schemes based on energy norm error estimates.     

Discrete-time complementary models and smoothing

The fact that the smoothing error is a (wide sense) Markov process is somehow surprising since smoothed estimates depend upon both past and future data. In this paper we first give a simple and general proof of this fact. Then we use the so-called complementary models introduced by Weinert and Desai to derive forwards and backwards markovian models for the smoothing error in state-space models. By exploring the structure of the complementary models we show that, under certain restrictions, only two simple structured models exist, one that runs forwards in time and the other that runs backwards in time. The forwards complementary model leads to the forward Rauch-Tung-Striebel (RTS) smoothing formula and to a backwards markovian model for the error, whereas the backwards model leads to the backward RTS formula and to a forwards error model. The two models for the smoothing error can be derived one from the other by a forward-backward transformation that preserves the sample paths. Finally, by using a combination of the two complementary models we give yet another proof for the two-filter smoothing formula.     

Simulating the behavior of software modules by trace rewriting

The trace assertion method is a module interface specification method based on the finite state machine model. To support this method, we plan to develop a specification simulation tool, a trace simulator, that symbolically interprets trace assertions of trace specifications and simulates the externally observable behavior of the modules specified. We first present the trace assertion method. Then we formally define trace rewriting systems and show how trace rewriting, a technique similar to term rewriting, can be applied to implement trace simulation     

Cyclic codes over F2[u]/(u4−1) and applications to DNA codes

The structure of DNA is used as a model for constructing good error correcting codes and conversely error correcting codes that enjoy similar properties with DNA structure are also used to understand DNA itself. Recently, naturally four element sets are used to model DNA by some families of error correcting codes. Hence the structure of such codes has been studied. In this paper, the authors first relate DNA pairs with a special 16 element ring. Then, the so-called cyclic DNA codes of odd length that enjoy some of the properties of DNA are studied. Their algebraic structure is determined. Further, by introducing a map, a family of cyclic codes over this ring is mapped to DNA codes. Hamming minimum distances are also studied. The paper concludes with some DNA examples obtained via this family of cyclic codes.     

Reliable and efficient a posteriori error estimates for finite element approximations of the parabolic p-Laplacian

We generalize the a posteriori techniques for the linear heat equation in Verfürth (Calcolo 40(3):195–212, 2003) to the case of the nonlinear parabolic $p$ -Laplace problem thereby proving reliable and efficient a posteriori error estimates for a fully discrete implicite Euler Galerkin finite element scheme. The error is analyzed using the so-called quasi-norm and a related dual error expression. This leads to equivalence of the error and the residual, which is the key property for proving the error bounds.     

Robust real-time algorithms for identification of linear multivariable time-varying systems

The paper presents a discussion on the problem of the robust real-time identification of linear multivariable time-varying dynamic systems working in a noisy environment. Two methodologically different approaches to the design of such algorithms are presented. The first is based on the one-step estimation, optimal in the sense of the minimal conditional mean-square error, combined with convenient approximations of the underlying error covariance matrix. The second is based on the general formulation of robustified stochastic approximation algorithms, characterized by a suitable non-linear transformation of normalized residuals. Particular algorithms are derived on the basis of step-by-step optimization with respect to the weighting matrix of the algorithm. Monte Carlo simulation results illustrate the discussion, and show the efficiency of the proposed robust algorithms in the presence of large disturbance realizations, the so-called outliers.