A two-stage algorithm for identification of nonlinear dynamic systems

This paper investigates the two-stage stepwise identification for a class of nonlinear dynamic systems that can be described by linear-in-the-parameters models, and the model has to be built from a very large pool of basis functions or model terms. The main objective is to improve the compactness of the model that is obtained by the forward stepwise methods, while retaining the computational efficiency. The proposed algorithm first generates an initial model using a forward stepwise procedure. The significance of each selected term is then reviewed at the second stage and all insignificant ones are replaced, resulting in an optimised compact model with significantly improved performance. The main contribution of this paper is that these two stages are performed within a well-defined regression context, leading to significantly reduced computational complexity. The efficiency of the algorithm is confirmed by the computational complexity analysis, and its effectiveness is demonstrated by the simulation results.     

Spectra: a specification language for reactive systems

We introduce Spectra, a new specification language for reactive systems, specifically tailored for the context of reactive synthesis. The meaning of Spectra is defined by a translation to a kernel language. Spectra comes with the Spectra Tools, a set of analyses, including a synthesizer to obtain a correct-by-construction implementation, several means for executing the resulting controller, and additional analyses aimed at helping engineers write higher-quality specifications. We present the language in detail and give an overview of its tool set. Together with the language and its tool set, we present four collections of many, non-trivial, large specifications, written by undergraduate computer science students for the development of autonomous Lego robots and additional example reactive systems. The collected specifications can serve as benchmarks for future studies on reactive synthesis. We present the specifications, with observations and lessons learned about the potential use of reactive synthesis by software engineers.

     

The first reactive synthesis competition (SYNTCOMP 2014)

International Journal on Software Tools for Technology Transfer - We introduce the reactive synthesis competition (SYNTCOMP), a long-term effort intended to stimulate and guide advances in the...     

Physical simulation of a two-stage control algorithm for an FMS

A combination of a physical simulator of a two-stage Flexible Manufacturing System (FMS) with a heuristic control algorithm is presented. There are three equivalent machines producing different products with variable speeds subject to disturbances which may delay the process. A single robot loads and unloads the machines. On the machine level, the control algorithm determines the machine's production speed and the next control point. On the system level, whenever it is detected that any machine will not be able to complete the production on time, an emergency is called and the remaining combined load of all the machines is redistributed among the machines so that the slowest one can get help from the others.     

A two-stage algorithm integrating genetic algorithm and modified Newton method for neural network training in engineering systems

A two-stage algorithm combining the advantages of adaptive genetic algorithm and modified Newton method is developed for effective training in feedforward neural networks. The genetic algorithm with adaptive reproduction, crossover, and mutation operators is to search for initial weight and bias of the neural network, while the modified Newton method, similar to BFGS algorithm, is to increase network training performance. The benchmark tests show that the two-stage algorithm is superior to many conventional ones: steepest descent, steepest descent with adaptive learning rate, conjugate gradient, and Newton-based methods and is suitable to small network in engineering applications. In addition to numerical simulation, the effectiveness of the two-stage algorithm is validated by experiments of system identification and vibration suppression.     

Recursive algorithm for the two-stage EFOP estimation method

A recursive algorithm for the two-stage empirical frequency-domain optimal parameter （EFOP） estimation method was proposed. The EFOP method was a novel system identification method for Black-box models that combines time-domain estimation and frequency-domain estimation. It has improved anti-disturbance performance, and could precisely identify models with fewer sample numbers. The two- stage EFOP method based on the boot-strap technique was generally suitable for Black-box models, but it was an iterative method and takes too much computation work so that it did not work well online. A recursive algorithm was proposed for dis- turbed stochastic systems. Some simulation examples are included to demonstrate the validity of the new method.     

An improved algorithm for the control synthesis of nonlinear sampled switched systems

A novel algorithm for the control synthesis for nonlinear switched systems is presented in this paper. Based on an existing procedure of state-space bisection and made available for nonlinear systems with the help of guaranteed integration, the algorithm has been improved to be able to consider longer patterns of modes with a better pruning approach. Moreover, the use of guaranteed integration also permits to take bounded perturbations and varying parameters into account. It is particularly interesting for safety critical applications, such as in aeronautical, military or medical fields. The whole approach is entirely guaranteed and the induced controllers are correct-by-design. Some experimentations are performed to show the important gain of the new algorithm.     

An algorithm for synthesis of the suboptimal control law for quasi-linear stochastic dynamical systems

We consider the information constrained optimization problem for stochastic dynamical systems governed by quasi-linear Ito equations. Let us describe the information constraints. We suppose that each control vector component depends on a prespecified set of precisely measured state vector components. In this article we present an algorithm for synthesis of the suboptimal control law. This control law is the linear feedback regulator. The linear parameter and the constant term of the regulator are polynomial functions of time. The algorithm is successfully applied to the problem of two-link robotic arm optimal control. These manipulators may be effectively used at space stations, e.g. for moving cargo in outer space.     

MIMO-GFDM系统中低复杂度动态禁忌搜索检测算法的改进

针对多输入多输出的广义频分复用（MIMO-GFDM）系统的等效信道矩阵维度极大，传统的MIMO检测算法复杂度高且性能不佳的问题，将大规模MIMO系统中的动态禁忌搜索（RTS）检测算法运用到MIMO-GFDM系统中，并解决了RTS算法初始值的求解复杂度高的问题。首先利用最小均方误差（MMSE）检测算法所用到矩阵的正定对称性将矩阵Cholesky分解，并结合Sherman-Morrison公式迭代计算初始值，降低了初始值求逆的高复杂度；然后以改进的MMSE检测结果作为RTS算法的初始值，从初始值逐步全局搜索最优解；最后通过仿真，对不同算法的迭代次数和误码率（BER）性能进行了研究。理论分析与仿真结果表明：在MIMO-GFDM中，所提改进RTS信号检测算法误码率远低于传统信号检测算法。在4QAM时，RTS算法大约有低于MMSE检测6 dB的信噪比性能增益（误码率在10^-3时）；在16QAM时，RTS算法大约有低于MMSE检测4 dB的信噪比性能增益（误码率在10^-2时）。与传统RTS算法性相比，所提改进算法在不影响误码率性能的同时降低了算法复杂度。     

Optimal planning for two-stage stochastic industrial systems

We consider the optimal planning problem for a certain class of industrial systems operating under uncertainty. We construct mathematical models, define optimization problems for the planning, propose efficient algorithms for solving them. We show examples of applied problems that can be formalized in this mathematical model.     

Safety synthesis for incrementally stable switched systems using discretization-free multi-resolution abstractions

Acta Informatica - Control of continuous and hybrid systems using discrete abstractions often suffers from scalability issues, due to the use of state space partitions as symbolic states. In this...     

A case study of a two-stage image segmentation algorithm

Multimedia Tools and Applications - Mumford-Shah (MS) model has attracted considerable research interests in the past decades. It is a classical and important approach for image segmentation. In a...     

Using constraint propagation in blackboard systems: a flexiblesoftware architecture for reactive and distributed systems

Constraint propagation is explained, and the integration of problem-solving components is discussed. Validity and completeness results are considered, and the extension of constraint propagation to reactive and distributed systems using a blackboard architecture is addressed     

基于模型的机组组合两阶段启发式算法

针对同时考虑机组爬坡速率约束和系统安全约束的机组组合问题,提出一个基于模型的两阶段启发式算法.第1阶段确定可行的机组启停状态,首先构造初始启停状态,并根据模型检验初始启停状态是否可行,如果不可行,则通过目标函数的线性近似和约束松弛构造问题的松弛模型,并将其用于可行化机组的启停状态;第2阶段利用经济分配模型确定机组的输出功率.基于118-母线电力系统的测试验证了所提出算法的有效性和鲁棒性.     

A two-stage algorithm for one-microphone reverberant speech enhancement

Under noise-free conditions, the quality of reverberant speech is dependent on two distinct perceptual components: coloration and long-term reverberation. They correspond to two physical variables: signal-to-reverberant energy ratio (SRR) and reverberation time, respectively. Inspired by this observation, we propose a two-stage reverberant speech enhancement algorithm using one microphone. In the first stage, an inverse filter is estimated to reduce coloration effects or increase SRR. The second stage employs spectral subtraction to minimize the influence of long-term reverberation. The proposed algorithm significantly improves the quality of reverberant speech. A comparison with a recent enhancement algorithm is made on a corpus of speech utterances in a number of reverberant conditions, and the results show that our algorithm performs substantially better.     

Aspect-oriented programming for reactive systems: Larissa,a proposal in the synchronous framework

Aspect-oriented programming (AOP) has emerged recently as a language concept for expressing cross-cutting concerns, mainly in object-oriented software. Since then, the concept has been applied to a wide variety of other contexts. In this paper, we explore some cross-cutting concerns for parallel programs of reactive systems: we propose an aspect language, Larissa, and a weaving mechanism, in a core language based on parallel communicating Mealy machines.     

Supervisory control and reactive synthesis: a comparative introduction

This paper presents an introduction to and a formal connection between synthesis problems for discrete event systems that have been considered, largely separately, in the two research communities of supervisory control in control engineering and reactive synthesis in computer science. By making this connection mathematically precise in a paper that attempts to be as self-contained as possible, we wish to introduce these two research areas to non-expert readers and at the same time to highlight how they can be bridged in the context of classical synthesis problems. After presenting general introductions to supervisory control theory and reactive synthesis, we provide a novel reduction of the basic supervisory control problem, non-blocking case, to a problem of reactive synthesis with plants and with a maximal permissiveness requirement. The reduction is for fully-observed systems that are controlled by a single supervisor/controller. It complements prior work that has explored problems at the interface of supervisory control and reactive synthesis. The formal bridge constructed in this paper should be a source of inspiration for new lines of investigation that will leverage the power of the synthesis techniques that have been developed in these two areas.     

Scheduling for reactive real-time systems

In designing Chinook, a hardware-software cosynthesis system for reactive real-time controllers, the impact of timing constraints on software scheduling has been a central concern. By dividing constraints into two levels, corresponding to low-level interactions with device interfaces and high-level real-time response and rate requirements, we have developed solutions tailored to each aspect. These scheduling techniques enable Chinook to map a high-level specification onto a specified collection of processors and peripheral devices while respecting performance requirements