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Acta polytechnica HungaricaVolume 13, Issue No. 4. (2016.)


  • Roman Koleňák ,
    Igor Kostolný :

    Abstract: The aim of this work was to evaluate the direct bonding of Al2O3, SiC ceramics and Cu substrates. Joints were fabricated by using 40 kHz frequency ultrasound. The Zn4Al solder wetted all materials studied and joints of good quality were produced. The shear strength attained with Al2O3 ceramics was 81 MPa. The strength with SiC ceramics was slightly lower at 65 MPa. In a copper substrate, we observed shear strengths of 84 MPa.

    Keywords: soldering; ceramic; metallic; microstructure; strength

  • Amira Gharbi ,
    Mohamed Benrejeb ,
    Pierre Borne :

    Abstract: The control of a process by poles placement is one of the most used forms of feedback control. It allows not only to stabilize a process, but also to control its dynamic. Furthermore, the optimal controls with quadratic criteria of linear systems in fact lead to the pole placement. In this work, we present an approach to the stabilization of nonlinear systems in presence of uncertainties using poles placement by state feedback and the determination of attractors by diagonalization of the characteristic matrices linearized around operating points and using aggregation techniques.

    Keywords: aggregation techniques; attractors; comparison systems; state feedback control; uncertain nonlinear

  • Jian-sheng Guan ,
    Lo-Yi Lin ,
    Guo-li Ji ,
    Chih-Min Lin ,
    Tien-Loc Le ,
    Imre J. Rudas :

    Abstract: Breast cancer is becoming a leading cause of death among women in the world. However, it is confirmed that early detection and accurate diagnosis of this disease can ensure a long survival of the patients. This study proposes a self-validation cerebellar model articulation controller (SVCMAC) neural network which can yield high accuracy of predication and low false-negative rate for breast cancer diagnosis. With its self-validation unit, the SVCMAC neural network has higher classification accuracy than the conventional CMAC neural network. The parameters of the receptive-field basis function and the weights are all updated first by training data, and the most suitable parameters are then chosen through the self-validation algorithm to retrain the neural network for better performance. Experimental results provide evidence that the SVCMAC neural network has a higher classification accuracy when compared with the BP neural network, LVQ neural network and CMAC neural network.

    Keywords: cerebellar model articulation controller; breast cancer diagnosis; self-validation

  • Kristína Machová ,
    Jozef Vrana ,
    Marián Mach ,
    Peter Sinčák :

    Abstract: The paper focuses on the field of ontology evaluation and visualization. Ontologies represent the essential technology for the development of the Semantic web applications. This technology has been proven to be useful in a range of applications for data manipulation and administration. The paper introduces an ontology visualization approach based on descriptive vectors. It offers the design of descriptive vectors representation for an ontology domain and also the algorithm design for generation of the descriptive vectors. This approach offers quick overview of the given ontologies content. In addition, this work presents the design of methods for comparison and evaluation of various ontologies based on descriptive vectors. Moreover, it introduces a method for ontology placing in the context within an ontological space (the map). Finally, a method for administration of user navigation in the ontological space is presented.

    Keywords: the Semantic web; ontology evaluation; ontology visualization; descriptive vector; key concept; user navigation

  • Sándor Molnár ,
    Ferenc Szidarovszky :
    An Alternative Method in Optimizing Random Outcomes77-86en [382.35 kB - PDF]EPA-02461-00066-0050

    Abstract: Within economic literature random outcomes can be characterized by their certainty equivalents. In this article, a general approach for their extension is first outlined and then special cases are shown. The two most simple of these cases result in the classical formula of certainty equivalent, and by increasing the degree of the approximating Taylor polynomials, more advanced formulas are derived. Additionally, a simple advanced formula is compared favorably to the classical approach in a computer study and some application models are discussed to illustrate the methodology.

    Keywords: decision making; uncertainty; applications

  • Monika Ratajczak ,
    Marek Malinowski ,
    Romuald Będziński :

    Abstract: Studies concerning the mechanical properties of the spinal cord are crucial for the understanding of various related pathologies. The present study introduces the results of an analysis focused around the mechanical properties of the two types of the mammalian spinal cord: domestic pig (Sus scrofa f. domestica) and domestic rabbit (Oryctolagus cuniculus f. domesticus). The research has been conducted in an in vitro environment, and the freshly dissected cords have been subjected to uniaxial tension testing. A series of preliminary tests allowed for the selection of the optimum method for fixing the cord in the chuck of the testing machine. All preparations were tested for 3 hours after the death of the animal, while an appropriate level of hydration, and the temperature and the strain rate of 0.08s-1 have been maintained. The nonlinear response of the tested tissues has been obtained under the force-displacement conditions. On the basis of the experimental studies the mechanical properties of the samples have been described. Additionally, numerical calculations have been performed on a simplified model of the spinal cord with the use of the finite element (FE) method, which were finally compared with the actual behavior of the sample tissues. An analytical approach with the hyperelastic Ogden material model and FE model of the spinal cord were employed to derive mechanical properties of the tested spinal cords. The results demonstrate that a non-linear FE model is able to predict the mechanical behavior of the spinal cords in the uniaxial tension.

    Keywords: spinal cord injury (SCI); nonlinear mechanical properties; finite element method (FEM); mechanical testing

  • Szilárd Jagasics ,
    István Vajda :
    Cogging Torque Reduction by Magnet Pole Pairing Technique107-120en [626.45 kB - PDF]EPA-02461-00066-0070

    Abstract: A high performance electrical drive needs a smooth torque waveform and a high torque to inertia ratio. The power density and performance needs can be, in most cases, fulfilled by using a permanent magnet synchronous machine (PMSM). This paper explores a new cogging torque reduction technique. This method can be used without reducing the power density of the machine and it can also be applied in a mass production process.

    Keywords: cogging torque; finite element analysis; optimization; pulsating torque reduction

  • Stipe Lovreta ,
    Jelena Končar ,
    Ljiljana Đ. Stanković :

    Abstract: There is a retailing revolution in progress, whose basic characteristic is strengthening the power of retailers. This strengthening causes shifting of the powers between members in the marketing channels and thus it leads to the change of positions and relationships within the channel. The trade revolution affects all the segments of goods and services, and it reflects, with the greatest extent and with special content, on the sphere of food and other products of everyday purchase and consumption. Precisely in this domain, the position of the large retail chains extremely strengthens in comparison to other players in the marketing channels. The effects which cause contemporary changes in the sphere of retail on relationships in the marketing channels are of substantial importance for functioning and survival of the channels. The question of a new position of producers in them is of special importance. All those, and especially smaller producers, are highly affected by the situation in which they are not able to resist the accumulated purchasing power of retailers. However, despite the fact that producers both face the ever-growing and more complex demands the large retail chains impose on them and at the same time become more dependent to the decreasing number of more and more powerful retailers, they also recognize the advantages of doing business with such partners. Simultaneously, the role of modern state is of high relevance. A state is expected to precisely and comprehensively define adequate rules for market players and to work intensively on their enforcement and sanctioning their infringement.

    Keywords: marketing channels; retail chains; producers, power

  • Vladimir Socha ,
    Patrik Kutilek ,
    Alexandr Stefek ,
    Lubos Socha ,
    Jakub Schlenker ,
    Karel Hana :
    Decision Making Process of Hexapods in a Model of Complex Terrains141-157 en [614.40 kB - PDF]EPA-02461-00066-0090

    Abstract: The paper describes behavior of a cognitive control system model, which enables a hexapod to walk in an obstacle-free terrain as well as in a complex terrain including obstacles. This cognitive system model is based on reinforcement learning and assumes the concept of static-stable walking. The decision making process was tested using three different types of terrain models. The results of decision making process trigger actions in the form of changes in the state of six-legged body to maintain stable walking forward. New method have been developed to describe a group of obstacles of different sizes in a complex terrain. The results suggest a relationship between the predefined number of actions and the maximum total walked distance in terrain. In case of the terrain without obstacles, the optimized actions are the same. Thus, the way of moving the trunk and legs in the terrain is always the same and cyclic. The results also indicate that the maximum total walked distance is reduced due to a growing number of obstacles to overcome. The maximum total walked distance is reduced more significantly in the case of overcoming a greater number of small obstacles compared the case of smaller number of large obstacles. The way of moving the trunk and legs in the terrain with large obstacles is acyclic. The methods proposed for the study of the cognitive system and the sensory system of a hexapod, for the simulation of six-legged walking, as well as for the characterization of terrain with obstacles may find application in bioengineering, robotics, military system and other fields.

    Keywords: complex terrain; obstacles; hexapod; reinforcement learning; static-stable walking

  • Miroslav D. Sokić ,
    Ilija B. Ilić ,
    Vaso D. Manojlović ,
    Branislav R. Marković ,
    Zvonko P. Guliąija ,
    Milan D. Pavlović ,
    Nada D. ©trbac :

    Abstract: The impact of various time-defendant factors on the recycling rate of end-of-life vehicles (ELV) in Republic of Serbia was investigated. Statistical distribution of the frequency of the number of ELV in the year of dismantling depending on the year of production of ELV is designed using the two-parameter Weibull distribution function and MATLAB software, based on a real time data. Obtaining the time-dependence of Weibull parameters, a statistical distribution of frequency of the number of ELV in the coming period in Serbia was simulated. These results in combination with amount of materials in the most abundant cars in Serbia were used to simulate the overall amount of materials, which are available for recycling, in the coming period. These results are essential for automotive recycling industry management, particularly for shredders, dismantlers and metal pre-processors.

    Keywords: dynamic model; ELV; recycling; secondary raw materials; simulation

  • Katalin Gambár ,
    Marianna Lendvay ,
    Rita Lovassy ,
    József Bugyjás :
    Application of Potentials in the Description of Transport Processes173-184en [557.46 kB - PDF]EPA-02461-00066-0110

    The most important equations of motion in physics are summarized in differential equations. Variational calculus is suitable to unify the different disciplines of physics; it is even classical mechanics, electrodynamics or modern field theories. The basic equations of the disciplines can be deduced from the least action principle, the Hamilton’s principle. It is shown that the Lagrange function can be formulated for dissipative processes, in systems with infinite degree of freedom, thus the Hamilton’s principle can be considered as a basis of the theory. The Lagrange function can be constructed by an introduced scalar (potential) field that defines the measurable physical quantities.

    In the present paper we will construct a Lagrangian density function in such a way that the field equations (equations of motion) are known, but these equations contain non-selfadjoint operators. For this, it is necessary to introduce potentials. We suggest what possible directions are open in the study of the system, through the elaboration of the mathematical model.

    Keywords: Hamilton’s principle; dissipation; potential; adjoint operator; canonical formalism

  • Gregor Rozinaj ,
    Marek Vančo ,
    Ivan Minárik ,
    Ivan Drozd ,
    Renata Rybárová :
    Extending System Capabilities with Multimodal Control185-204en [718.87 kB - PDF]EPA-02461-00066-0120

    Abstract: Multimodal interface (MMI) is the first layer from a user point of view to interact with most IT systems and applications. MMI offers natural and intuitive interface for user identification and system navigation. Typical features of multimodal control contain user identification based on face recognition and speaker voice recognition, system control based on voice commands and gesture recognition. Several examples show typical applications with MMI like voting or direct shopping while watching TV.

    Keywords: multimodal interface; gesture control; gesture recognition; voice navigation

  • Aleksandar Takači ,
    Ivana ©tajner-Papuga ,
    Darko Drakulić ,
    Miroslav Marić :

    Abstract: The aim of this paper is to demonstrate the applicability of the Choquet integral, a well-known fuzzy integral, in the Maximal Covering Location Problem (MCLP). Possible benefits of the used integral, which is based on monotone set functions, include the flexibility of а monotone set function, which is in the core of the Choquet integral, for modeling the Decision Maker's behavior. Various mathematical models of the Maximal Covering Location Problem are given. The approach, based on the Choquet integral versus the standard approach, is thoroughly discussed and illustrated by several examples.

    Keywords: Maximal Covering Location Problem; monotone set function; Choquet integral

  • Arash Hakimi Tehrani ,
    Edgar Dörsam :

    Abstract: Because pad printing can be used on 3-D substrates, it has attracted the attention of many researchers in the field of printed electronics. This paper presents developments in the automation of a pad printing machine that improve its specifications for use in scientific fields and equip it with some unique features. Users of this machine can obtain graphs of printing force and printing step durations for tracing and analyzing the printing process. Here, to explain the design method, the printing technique features, the pad printing working process and related machine parts, as well as the development and design process, are described. In this section, some hardware, such as National Instruments CompactRIO, as well as software (LabVIEW) and data transferring under the EtherCAT protocol will also be discussed. Finally, the machine user interface and some analytical graphs of the machine will be explained.

    Keywords: Automation pyramid; Mechatronic system structure; Indirect gravure printing; Pad printing control system; LabVIEW