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Acta polytechnica HungaricaVolume 11, Issue No. 2 (2014.)


  • Áron Kincses, ,
    Géza Tóth :

    Abstract: In this paper the authors wish to introduce an application of the gravity model through a concrete example. In their investigation the gravity model was transformed to analyse the impact of accessibility in a way, that not only the size of gravitational forces but their direction can also be measured. Displacements were illustrated by a bi-dimensional regression. The aim of this paper to give a new perspective to the investigation of spatial structure through a Hungarian example. This makes easier the transport planning and land development modeling. In our work accessibility analysis, gravity modeling, bi-dimensional regression calculations and GIS visualization were performed

    Keywords: gravity model; bi-dimensional regression; accessibility; spatial structure; Hungary

  • Claudiu Pozna ,
    Radu-Emil Precup :
    Applications of Signatures to Expert Systems Modelling21-39en [342.26 kB - PDF]EPA-02461-00048-0020

    Abstract: This paper offers a new approach that applies the signatures to expert systems modelling. Signatures and their operators, viewed as a generalization of fuzzy signatures, represent a convenient framework for the symbolic representation of data. The models are derived by a three-step algorithm that maps the signatures onto expert systems. An expert systems modelling algorithm is given. Our algorithm has two inputs, the knowledge base, i.e., the rules, and the data base, i.e., the facts, and it constructs the signatures which represent models of expert systems. The algorithm is advantageous because of its systematic and general formulation allowing for the modelling of uncertain expert systems. The theoretical results are exemplified by a case study which produces models of a Bayesian expert system with mechatronics applications.

    Keywords: expert systems; mechatronics; modelling; operators; rules; signatures

  • ®ivadin Micić ,
    Momčilo Vujičić ,
    Vera Lazarević :

    Abstract: The paper presents a comparative and multicriteria statistical analysis of knowledge base units as shown on the examples of standardized subfields of electrical engineering. A number of objectives have been realized on knowledge pathways, both globally and locally, and initial hypotheses have been confirmed. Ranking/clustering among standardized fields and subfields has been carried out based on time-frequent innovations presented by knowledge base unit quantities and values. Web applications for analysis and singling out of samples from the entire Web-population of local (SRPS) and global (ISO) standardization have been developed and implemented. These applications represent a significant contribution to authenticity, particularly the authenticity of statistical research methodology. Original regression equations with accompanying indices of quantity, knowledge base unit values and ranking have been developed on the examples within the field of electrical engineering. Results of this study enable the realization of some higher practical objectives, i.e., (1) modification of teaching subjects and improving educational and financial resources for the quality of knowledge, (2) ranking of both narrow and broad standardized technologies and scientific fields.

    Keywords: electrical engineering; knowledge; standardization; SRPS; ISO; subfield

  • János Kundrák ,
    Zoltán Pálmai :

    Abstract: The traditional Taylor formula T=f(vc) gives tool life of the cutting tool T as a function of the cutting speed at constant speeds in which the higher the speed, the lower the tool life. However, in a wider technological range, the function T=f(vc) has extreme values as well, which can be described by the general tool-life function. Frequently the tool is used until full wear of the edge at changing or alternating speeds, for which the general tool-life function can be extended. By using this extension, the general tool-life equation can be defined even under manufacturing conditions. Its applicability is demonstrated for examples of taper-turning and cutting optimisation.

    Keywords: hard turning; tool life; economical cutting

  • Marc Piazolo :

    Abstract: The objective of this paper is to demonstrate the mechanism by which the European Central Bank (ECB) has been successfully absorbing excess liquidity – albeit to a small extent. These Fine Tuning Operation (FTO) were introduced to neutralize the liquidity effects of the Securities Markets Programme initiated in May 2010. With an out-of classroom experiment, students simulated investment decisions for financial institutions which needed to park excess liquidity with the ECB through an auction process that replicates the Fine Tuning Operations in place. The auctions showed to be very competitive, thereby enhancing the students understanding of the real word behaviour of major European financial institutions. A thorough analysis of the bidding results and the various determinants of total profits is presented. We start with describing as well as analyzing the evolution of the ECBs’ monetary policy instruments.

    Keywords: Financial crisis; monetary policy instruments; auction design; experimental economics

  • Ferenc Szlivka :
    Different Mathematical Solutions on Gas Oscillation101-115en [600.68 kB - PDF]EPA-02461-00048-0060

    Abstract: The mathematical description of gas-pressure oscillations excited by a piston at the end of a straight duct has been investigated in an analytical way and it has been compared to numerical solutions and measured results. Two different analytical solutions have been found in the literature in series form which have been transformed into closed form solutions showing their identity. This evaluation can significantly be simplified and the comparison of the results of the analytical and the numerical solutions are presented in this study accordingly. In the results are presented the frequency of piston is close to the resonant frequency.

    Keywords: gas pressure oscillation; analytical solution; infinite series; closed form

  • Vladimir Mladenović ,
    Miroslav Lutovac, ,
    Dana Porrat :

    Abstract: Many researchers start their work by studying theory in order to get better insight into measured phenomena. Sometimes they cannot get the numeric values of parameters used in published equations. This is even more complicated when the theory is statistical and there are no closed form deterministic solutions. In this paper we introduce an original approach and method to analyzing a popular and frequently cited tutorial paper on Expectation-Maximization (EM) algorithm. The original paper has sufficient information to understand the algorithm. Using tools of Computer Algebra System and methods of Symbolic Processing (SP), the typewriting errors are discovered and the re-derived equations are used for automatic generation of algorithmic code. The examples are evaluated using automatically derived code and the final numeric values agree with the values from the original paper. The derived results are used for further optimization, such as deriving the computational error in the closed form. From the closed form solutions, the precision can be derived in terms of number of iterations, or the minimal number of iterations can be expressed in terms of the required precision. This helps to optimize the algorithm parameters so that the algorithm becomes more efficient.

    Keywords: Symbolic processing; EM algorithm; iteration; convergence; ML estimation; Computer algebra system

  • Horváth Richárd ,
    Ágota Drégelyi-Kiss ,
    Gyula Mátyási :
    Application of RSM Method for the Examination of Diamond Tools137-147en [692.65 kB - PDF]EPA-02461-00048-0080

    Abstract: The aluminium alloys are used by the automotive, aerospace industries increasingly because of their numerous advantageous mechanical and chemical properties. The cutting of such aluminium alloys is performed with almost exclusively diamond tools. The most often used work piece materials are the so-called Al-Si and Al-Mg-Si alloys, of which the most widespread are reinforced aluminium-silicon alloys. In the practice of technology planning, the average value of surface roughness and surface height of machined work pieces are as important criteria as geometrical sizes (e.g.: length, diameter tolerance). The authors in this article examine the cutting performance of diamond tools having different edge materials with the help of design of experiment. The correlation between the examined surface roughness and the cutting performance was evaluated; additionally the optimal cutting parameters were determined.

    Keywords: fine turning; design of experiment; response surface method; aluminium alloy; surface roughness measurement; optimal cutting parameter

  • Hajdu Zuzana ,
    Marek Andrejkovič ,
    Ladislav Mura :

    Abstract: The improvement of business processes is a necessary part of innovations in business, aimed at improving of customer satisfaction and achieving more reliable productions. The above mentione of steps are inevitable in today’s world of high competitiveness and therefore the need for improvement of competitive abilities of an enterprise and its products grows steadily. Excessive error rate creates additional costs that are reflected in the price of the product. This is the reason for less effective competitive ability of the given product. Therefore, this contribution shows designed experiments as a method of decreasing error rate in production processes.

    Keywords: Quality; business processes; DOE; process improvementt

  • Szilvia Bíró-Szigeti :

    Abstract: This paper discusses residential energy saving market in Hungary, applying a relatively new method. The study is a comprehensive presentation of the results of an extensive research, exploration of relationship systems and system-based processing, in the framework of which the design, the implementation and the operation of the energy investments of buildings takes place. The market is examined with strategic approach and the reseach findings are systematized in intuitive ways with the method of technology roadmapping (TRM). These aspects of analysis give new and original contribution to the Hungarian building energetics sector and energy policy. The results are obtained from interviews and questionnaire survey with representatives of stakeholder groups and experts. The establishment of residential energy saving investments is highly influenced by environmental factors, technological development of building energy market and stakeholders interests and the interrelation of all these. The problems originate mostly in the long-standing lack of the comprehensive strategic plans and marketing tools of building energetics enterprises and concrete objectives and state's guidelines for the residential market of building energetics.The aim of the study is to serve as a practical instrument for the decision-makers, it can promote more efficient planning, support and implementation of residential energy saving investments.

    Keywords: energy saving; strategy; technology roadmapping; TRM

  • Software Environment for Learning Continuous System Simulation187-202en [592.13 kB - PDF]EPA-02461-00048-0110

    Abstract: In this paper, we describe a new graphical environment for learning continuous simulation. This open source software solution enables engineering students to learn and understand various real system models in the CSMP (Continuous Simulation Modelling Programme) language easily, and at the same time learn about the implementation aspects of simulation languages. The software provides efficient tools for creating, storing, and executing continuous system simulation models that are described with differential equations. The graphical block-diagram interface allows students to drag-and-drop predefined modelling blocks, connect them together and create different models of continuous systems. Further, we present an example of using the developed application in solving a typical continuous simulation problem. Finally, we present the results of the evaluation performed on a testing sample of 160 students of undergraduate course Simulation and simulation languages at the Faculty of Organizational Sciences, University of Belgrade.

    Keywords: Continuous system simulation; teaching simulation and simulation languages; CSMP software

  • Abstract: This paper presents the application of time-series and artificial neural network for improvement of energy forecasting in rail transport section. An integrated artificial neural network (ANN) model is presented that uses autocorrelation and partial autocorrelation functions to determine the best input variables for ANN. The proposed ANN uses autocorrelation function (ACF) and partial autocorrelation function (PACF) extracted from time-series data to select appropriate inputs for ANN. For validation of the ANN results, they are compared with two auto regressive models using analysis of variance (ANOVA) technique. Weekly total gasoil consumption in Iran railway transportation from January 2009 to October 2011 is used for constructing and comparison time-series and ANN models. Result shows that ANN with inputs extracted from ACF and PACF analysis, performs well for estimation of railway gasoil consumption. The interaction between input variables as well as non-linearity in consumption data is properly handled by the proposed integrated ANN.

    Keywords: Gasoil Consumption Forecasting; Railway; Artificial Neural Network; Time-series; Autocorrelation

  • István Szalóki ,
    Sándor Csuka ,
    Sándor Sipos :
    New Test Results in Cycloid-Forming Trochoidal Milling215-228en [653.74 kB - PDF]EPA-02461-00048-0130

    Abstract: The different types of trochoidal milling are widely used in order to produce grooves and slots. These procedures can be purchased as a built-in option of modern controls or they can be generated by modelling the movements of the tool path. In addition to the advantages, arising during machining (lower load on the milling tool and machine, the possibility to apply increased cutting parameters, raised productivity and tool durability) there is a disadvantage, to be mentioned: it is the forming of laces on the machined surface. In the present paper our trials will be introduced where a modelled cycloid-forming milling method is used to determine the effect of the cutting data, performed on the result parameters (force effects, accuracy, surface microgeometry). The tests were executed systematically, with the help of Experiment Design. Based on the results, gained during the tests, the force, accuracy and microgeometrical limits can be determined, being characteristic to this machining type.

    Keywords: slot milling; semicircular milling; zigzag milling; trochoid milling; productivity; force effects; microgeometry

  • Gulzhan Buldybayeva :

    Abstract: Given article covers some special aspects of Corporate Social Responsibility in the oil and gas industry of Kazakhstan. The research deals with the analisys of activities of Kazakhstani multinational companies similarly to other transnational corporations of exploration and production industry in developing countries, which belongs to good or the darker side of the responsible acts. Recommendation demonstrating with a case study how to develop a better strategy for corporate social responsibility which helps leading Kazakh oil and gas joint venture company to avoid the possible occurrence of the CSR Dark side is presented in this article

    Keywords: corporate social responsibility; developing countries; oil and gas industry, exploration and production; case study; Dark side