A new backward shift algorithm for system identification by a good choice of frequencies

In this study, we propose a novel backward shift algorithm for pole estimation of linear time-invariant (LTI) systems. By making adjustments, we address the question: How should the frequencies of input signals be chosen? We select the frequencies based on algebraic accuracy in the numerical integral and use the Gaussian–Legendre formula in this process. After poles are located, the discrete Fourier transform (DFT) and the new backward shift algorithm (new BSA) along with the least squares (LS) method are used to identify the systems. Two examples show that the proposed method for pole estimation performs better and the corresponding identification algorithm is practical.     

单输入单输出系统的同时稳定:多项式方法

基于系统的传递函数表示,讨论了两个SISO对象的同时稳定问题,给出了该问题有解的充要条件.得出了两个SISO对象中的一个的闭环极点可以任意配置而另一个对象的闭环极点则有赖于两个对象的零极结构的结论.     

A criterion of closedness of an attainable set of a delay system

This paper deals with the problem of closedness of an attainable set of a delay system in the state space W²₁. We give a necessary and sufficient condition of closedness expressed in terms of the transfer matrix of the system.     

基于小波算法的二阶线性定常分布参数系统的辨识

本文基于正交函数逼近方法,借助于小波变换,并利用其运算矩阵及其运算性质,研究了分布参数系统的辨识问题。将Haar小波正交基应用于分布参数系统的辨识中,经正交小波逼近变换,将原偏微分描述的分布参数系统转化为代数矩阵方程,并且,考虑了初始条件和边界条件,获得了算法简单、计算方便、具有较高精度的辨识算法,简化了分布参数系统辨识的求解过程,应用在分布参数系统辨识中不失为一种有效的分析方法。仿真实例表明了本文所提出的算法的有效性。     

Characterisation of nonlinear and linear time-varying systems by Laplace transformation

In this article we elaborate on various characterisations of nonlinear systems. Specifically, we focus on the frequency-domain characterisation of the class of single-input single-output (SISO) linear time-varying (LTV) systems. We use the model introduced by Wiener using Volterra functional and later elaborated by others. The application of the multidimensional Laplace transform (MDLT) method as a fundamental tool in analysing variable systems and understanding system dynamic behaviours is emphasised. In particular, applications of double or two-dimensional Laplace transform (2DLT) for the analysis and synthesis of LTV circuits and systems are detailed. Examples worked out that illustrate the method and demonstrate its validity in the frequency-domain.     

A genetic fuzzy system to model pedestrian walking path in a built environment

A study on the pedestrian’s steering behaviour through a built environment in normal circumstances is presented in this paper. The study focuses on the relationship between the environment and the pedestrian’s walking trajectory. Owing to the ambiguity and vagueness of the relationship between the pedestrians and the surrounding environment, a genetic fuzzy system is proposed for modelling and simulation of the pedestrian’s walking trajectory confronting the environmental stimuli. We apply the genetic algorithm to search for the optimum membership function parameters of the fuzzy model. The proposed system receives the pedestrian’s perceived stimuli from the environment as the inputs, and provides the angular change of direction in each step as the output. The environmental stimuli are quantified using the Helbing social force model. Attractive and repulsive forces within the environment represent various environmental stimuli that influence the pedestrian’s walking trajectory at each point of the space. To evaluate the effectiveness of the proposed model, three experiments are conducted. The first experimental results are validated against real walking trajectories of participants within a corridor. The second and third experimental results are validated against simulated walking trajectories collected from the AnyLogic® software. Analysis and statistical measurement of the results indicate that the genetic fuzzy system with optimised membership functions produces more accurate and stable prediction of heterogeneous pedestrians’ walking trajectories than those from the original fuzzy model.     

Fuzzy control of an ANFIS model representing a nonlinear liquid-level system

This paper aims to serve two main objectives; one is to demonstrate the modelling capabilities of a neuro-fuzzy approach, namely ANFIS (adaptive-network based fuzzy inference system) to a nonlinear system; and the other is to design a fuzzy controller to control such a system. The nonlinear system, which is a liquid-level system, is represented first by its mathematical model and then by ANFIS architecture. The ANFIS model is formed by means of input–output data set taken from the mathematical model. Then a PID-type fuzzy controller, which linguistically approximates the classical three-term compensation, was designed to control the system represented by both its mathematical and ANFIS models in order to perform an agreement comparison between them. It is shown that the ANFIS architecture can model a nonlinear system very accurately by means of input–output pairs obtained either from the actual system or its mathematical model. It is also shown that such a system can be controlled effectively by a fuzzy controller.     

一种应用于无线通讯终端中GUI模型的设计与实现

在进行嵌入式系统的软件设计过程中,应用层GUI的设计是一个非常重要的部分.由于实时操作系统的引入,用户界面的设计就从传统的顺序执行变成了以消息驱动方式进行用户界面响应.采用了OOP的思想,构建了一种适用于无线通讯终端系统(包括GSM通讯终端,PHS通讯终端,CDMA通讯终端)软件设计中通用的GUI模型,并给出了在C语言开发工具下的实现,以一个待机状态下主菜单界面讲述了模型中状态迁移的具体实现过程.该GUI模型具有结构简单,实现方便,便于扩展等特点,目前已用于笔者开发的PHS移动终端的系统软件中,实践证明该模型使用效果良好.     

A model of a bi-directional transfer mechanism using rule combinations

This paper proposes a new type of transfer mechanism, called Rule Combination Transfer (or RCT), that produces an output structure by non-destructively combining target parts of translation rules, each of which consists of dependency structures in source and target languages and correspondences between them. This proposed mechanism employs more extended mapping of correspondences than one-to-one mapping used in conventional transfer systems, to allow expression of some peculiar or exceptional translation phenomena. Further, these translation rules can be used bi-directionally. Although, the proposed transfer mechanism is intended to be a foundation for an example-based transfer system by coupling it with a mechanism selecting translation rules based on the similarity with an input, it can be also used as a foundation for a conventional transfer system.     

A semantically complete extension sequence of the system L

In this paper, the method of well-combined semantics and syntax proposed by Pavelka is applied to the research of the propositional calculus formal system L*. The partial constant values are taken as formulas, formulas are fuzzified in two manners of semantics and syntax, and inferring processes are fuzzified. A sequence of new extensions {Ln*} of the system L* is proposed, and the completeness of Ln* is proved.     

A model of a trust-based recommendation system on a social network

In this paper, we present a model of a trust-based recommendation system on a social network. The idea of the model is that agents use their social network to reach information and their trust relationships to filter it. We investigate how the dynamics of trust among agents affect the performance of the system by comparing it to a frequency-based recommendation system. Furthermore, we identify the impact of network density, preference heterogeneity among agents, and knowledge sparseness to be crucial factors for the performance of the system. The system self-organises in a state with performance near to the optimum; the performance on the global level is an emergent property of the system, achieved without explicit coordination from the local interactions of agents.     

A semantically complete extension sequence of the system (?)

In this paper, the method of well-combined semantics and syntax proposed by Pavelka is applied to the research of the prepositional calculus formal system (?)*. The partial constant values are taken as formulas, formulas are fuzzified in two manners of semantics and syntax, and inferring processes are fuzzified. A sequence of new extensions {(?)_n~*} of the system ? is proposed, and the completeness of (?)_n~* is proved.     

具有动态补偿能力的神经网络模型及其在动态系统建模中的应用

本文在多层前馈神经网络模型基础上，引入误差动态反馈环节，从而形成一种新的具有动态补偿能力的神经网络模型。新模型的训练利用反向传播原理实现。采用该模型对非线性动态系统进行建模时，能显著提高建模精度，特别是在网络模型工作时，对新出现的输出误差具有动态补偿能力，文中给出了新网络模型的结构和学习算法，最后是仿真实例。     

Characterisation of a desktop LCD projector

A typical desktop LCD projector was characterised. Having determined the optimum settings of the brightness and contrast controls, measurements were made with a spectroradiometer to establish the additivity of the primaries, inter-channel dependence, colour gamut, tone scale, contrast, spatial non-uniformity, temporal stability and viewing angle variation. Four mathematical models were compared for their accuracy in predicting the colours generated by the display for arbitrary signal inputs. A new model was developed for the S-shaped electro-optical transfer function of the LCD device, and was extended to predict the anomalous colour tracking of the primaries.     

一种应用于地球系统模式的通用插值算法模型

地球系统模式的现有插值算法误差较大、网格适用性差,无法满足其未来的发展需求。提出了一种插值算法分类方法,根据此方法设计了一个通用插值算法模型。该模型基于复合算法的思想,既可表示现有算法,还可通过选择适当的两个算法灵活构造出局部的高精度的新算法。根据此模型并利用径向基函数良好的插值效果提出了两个新的插值算法。基于球面Voronoi图的搜索算法可有效优化插值算法的实现。实验结果表明新算法具有良好的插值效果。     

A real-time intelligent gas sensor system using a nonlinear dynamic response

We developed an intelligent gas sensor system for discrimination and quantification of gases by a single semiconductor gas sensor in real-time. This system is based on the information embedded in a nonlinear dynamic response. By applying a sinusoidal voltage to a heater attached to a sensing material, a characteristic time-dependent trace of the sensor resistance is obtained as a response to environmental gases. In order to evaluate the characteristic response in a quantitative manner, fast Fourier transformation (FFT) was performed for the dynamic response. Higher harmonics, obtained by performing FFT, were processed by using a discrimination method and a multiple regression. It is possible for the system to respond in the time order of several seconds. The physico-chemical meaning of the response was also discussed.     

A simulation study with a combined network and production systems model of pilot behavior on an ILS-approach

A simulation study was conducted for determining information flow requirements of a pilot-cockpit interface during an ILS-approach. Study steps for modeling, simulating, and analyzing system processes are discussed. Starting with the problem definition which includes relevant flight processes, the network of pilot tasks, and performance measures, the conceptual model of processes is mathematically described by means of algebraic and difference equations as well as production systems. To transform the model into a simulation program, the simulation language SLAM is used. SLAM elements utilized for modeling flight processes and pilot tasks as well as the procedure of model validation are discussed. The analysis of simulation output data, i.e. state trajectories and task timelines, results in the determination of important information requirements useful in early stages of a design project.     

一类不确定性系统鲁棒H∞控制器

研究一类具有匹配不确定性系统鲁棒H∞控制问题,第一,基于矩阵不等式给出了二次稳定的条件并且对系统的H∞性能进行了分析;第二,给出了系统的鲁棒H∞控制器,该控制器不仅满足系统二次稳定的条件,而且也满足H∞性能约束条件;最后,数值算例说明了控制器的有效性和可行性。