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Acta polytechnica HungaricaVolume 5, Issue No. 4 (2008.)


  • Jozef Kelemen :
    A Short Note on Emergence of Computational Robot Consciousness5-13en [164.59 kB - PDF]EPA-02461-00016-0010

    Abstract: A way is sketched how to answer the question about the computational power supposed behind the consciousness, esp. the computational robot consciousness. It is illustrated that a formal model of the possible functional architecture of certain type of robot enables to satisfy the test of emergence proposed earlier.

    Keywords: Robots, Machine Consciousness, Emergence, Eco-Grammar Systems

  • Imre Kiss ,
    Stefan Maksay :

    Abstract: The technical conditions, which are imposed to the cast iron rolls in the exploitation period, are very different and often contradictory. The obtaining of various physical and mechanical properties in the different points of the same foundry product meets difficult technological problems in the industrial condition. One of the parameters, which determine the structure of the irons destined for rolls casting, is the chemical composition. If we not respect this composition, which guaranties the exploitation properties of the each roll in the stand of rolling mill, it will lead to rejection. Alloying elements have in principle the same influence on structure and properties. This paper suggest a mathematical interpretation of the influence of the main alloy elements over the mechanical characteristics (the hardness on the crust and on the necks of the rolls) of this nodular irons, resulting the average values and average square aberration of the variables HB, and the main alloying elements (Cr, Ni, Mo), the equations of the hyper surface in the four dimensional space. For the statistical and mathematical analysis, there were used 23 industrial cases. The resulted surfaces, belonging to the three-dimensional space, can be represented and, therefore, interpreted by technologists. Knowing these level curves allows the correlation of the values of the twos independent variables so that the hardness can be obtained in between the requested limits. The paper presents the results of some researches regarding the chemical composition of the nodular irons destined for casting half-hard rolls. It is presented, in graphical form, used the Matlab area, the influence of the main alloying elements upon the hardness, and measured on the necks and the core of the rolls, respectively on the working surface (body) of these very important rolling mill components The realization of an optimal chemical composition can constitute a technical efficient mode to assure the exploitation properties, the material from which the rolling mills cylinders are manufactured having an important role in this sense. From this point of view is applied the mathematical molding, which is achieved starting from the differentiation on rolls component parts, taking into consideration the industrial data obtained from the hardness mensuration on rolls, which recommends the hardness, for different chemical compositions.

    Keywords: iron rolls, alloying elements, hardness, modelling, graphical addenda

  • Martin Tomášek :

    Abstract: This paper presents a type system of mobile ambients suitable for expressing communication and mobility of mobile code application. The main goal is to avoid ambiguities and possible maliciousness of some constructions in mobile ambients. The type system presents behavioral scheme that statically defines and checks access rights for authorization of ambients and threads to move. We proved the soundness theorem for the type system and we demonstrated the system by showing how to model mobile code paradigms.

    Keywords: ambient calculus, mobile code, type system

  • Salima Meziane ,
    Riad Toifouti ,
    Hocine Benalla :

    Abstract: This paper, we propose the comparative study between the performances of the proposed controller and field oriented control. With an aim of improving the field oriented control, the control of the induction motor by Input-Output linearization techniques are used to track torque and rotor flux and the scheme is extended for speed control is presented. The methods are compared in terms of their ability to handle loads on the motor shaft, their speed tracking capability and their sensitivity to operating condition variations. To estimate the rotor flux, an open loop observer the Extended Kalman Filter (EKF) algorithm is used. A reduced dynamic motor model is used which reduces the computational requirements of the EKF. Simulation results show the effectiveness of the proposed method.

    Keywords: nonlinear control, induction motors, field orientation, input output linearization, Kalman Filter

  • Miloš Oravec ,
    Miroslav Petráš ,
    Filip Pilka :
    Video Traffic Prediction Using Neural Networks59-78en [647.91 kB - PDF]EPA-02461-00016-0050

    Abstract: In this paper, we consider video stream prediction for application in services like video-on-demand, videoconferencing, video broadcasting, etc. The aim is to predict the video stream for an efficient bandwidth allocation of the video signal. Efficient prediction of traffic generated by multimedia sources is an important part of traffic and congestion control procedures at the network edges. As a tool for the prediction, we use neural networks – multilayer perceptron (MLP), radial basis function networks (RBF networks) and backpropagation through time (BPTT) neural networks. At first, we briefly introduce theoretical background of neural networks, the prediction methods and the difference between them. We propose also video time-series processing using moving averages. Simulation results for each type of neural network together with final comparisons are presented. For comparison purposes, also conventional (non-neural) prediction is included. The purpose of our work is to construct suitable neural networks for variable bit rate video prediction and evaluate them. We use video traces from.

    Keywords: data prediction, video traffic, neural network, multilayer perceptron, radial basis function network, backpropagation through time

  • Lajos Izsó ,
    Péter Tóth :

    Abstract: In Hungary, a lot of electronic-based syllabuses have been developed during the last 8-10 years at a most considerable cost. However, not much has been heard of their success or efficiency, as would be supported by scientific testing. First, the present study is to provide a survey of our project, which aimed at creating an integrated electronic learning environment. The processing of an education technology syllabus integrated in the Moodle virtual learning environment system took place in the passing academic year. The analysis of student behaviour in the learning environment is based on log files created on the server during the course of interaction between learners and the electronic syllabus. We analysed the learning activity of the students in the learning environment in exact numeric terms by using methods of web-mining. The second part of the study presents some of our first empirical results in this field.

    Keywords: virtual learning environment, collaborative learning, constructivist pedagogy, web-mining method

  • Anna Jadlovská ,
    Nikola Kabakov ,
    Ján Sarnovský :

    Abstract: This paper provides two approaches for design of Generalized Predictive Control (GPC) algorithm for a non-linear dynamic system. In the classical approach of the GPC strategy the recursive method of least square is considered for calculating of the linearized model parameters from the known analytic description of a particular non-linear system. The other purpose of this paper is to show an intelligent approach in which a feed-forward neural network (Multi Layer Perceptron – MLP) is used for modeling the same non-linear system within the frames of the predictive control. The possibility of on-line estimation of an actual parameters from the off-line trained neural model of the non-linear system by means method of the instantaneous linearization in each sample point is considered in GPC algorithm design. The validity of classical and neural GPC strategy is tested by computer simulations in Matlab/Simulink language using architecture of S-functions of the library PredicLib.

    Keywords: non-linear dynamic system, neural model, parametric estimation, predictive control algorithm

  • Mónika Fodor ,
    Ágnes Csiszárik-Kocsir :

    Abstract: In our present paper we examine the role of the value system and lifestyle as reflected in our primary research carried out among a representative consumer sample. In our opinion the differentiating effect of the individual value system as secondary segmentation criterion can be reflected in the market of life assurance, the basis of our research. By means of factor analysis we created value system structures and with the help of cluster analysis the main criteria of value system-based segments were outlined. As a result of the research we concluded that the individual value system was one of the most determining factors in taking out life assurance. The consumer segments formed alongside the value system have more differentiated attitudes than those of life assurance. Getting to know these groups more thoroughly and deeply offers opportunity for the „suppliers” of the life assurance market to create an effective marketing mix.

    Keywords: value system, factor analysis, cluster analysis

  • Ezedeen Kodeekha :

    Abstract: This paper deals with scheduling problems of the Flexible manufacturing systems (FMS). The objective is to improve the utilization of FMS. Lot Streaming (LS) is used to meet this objective.

    In this paper a comparative study is performed between the applications of new methods: Brute Force method (BFM) and Joinable Schedule Approach (JSA). Case studies for Flow Shop Systems (FSS) are performed. Attached independent sequence setup times are considered. It is concluded that these methods can be used effectively to solve LS problems. In the paper a general optimization mathematical model of LS for FMS scheduling problems of FSS is developed and presented.

    Keywords: FMS Scheduling, Scheduling Priority Rules, Lot Streaming, Global Minimum of Production Time, Excess Time Coefficient, Brute Force Method, Joinable Schedule Approach

  • Gábor Kiss :

    Abstract: While education is based on a national basic curriculum in Hungary, Germany’s 16 regions each with it’s own Ministry of Education determine curricula independently resulting in difficulties for school switching students. Standards of computer science education varying in different regions is discussed along with efforts to unify the curricula. Differences in CS education of the two countries are pointed out. In order to make the two education system comparable a web-based on-line questionnaire was prepared by the author. Students are to fill in from all regions and in all grades in both Germany and Hungary. The questionnaire and evaluation methods are discussed together with first results.

    Keywords: Computer Science Education, German, Hungarian, Comparison Method