a borítólapra  Súgó epa Copyright 
Acta polytechnica HungaricaVolume 13, Issue No. 5. (2016.)


  • István Bíró ,
    Béla M. Csizmadia ,
    Gusztáv Fekete :

    Abstract: For determining kinematical landmarks of the human knee joint, anatomical conventions and reference frame conventions are used by most of research teams. Considering the irregular shapes of the femur and the tibia, the anatomical coordinate systems can be positioned with 1-2 mm and 2-4 degree position deflections. However, most of the anatomical landmarks do not appear as a dot, rather as a small surface. For this reason, the optical positioning of anatomical landmarks can only be achieved by additional 1-2 mm position deflection. It has already been proven by other authors that the application of reference frames with different positions and orientations cause significant differences in the obtained kinematics (specific anatomical landmarks and angles) of human knee joint. The goal of this research is to determine the relationship between certain anatomical landmarks and reference frames having different positions and orientations. The investigations were carried out on cadaver knees by means of actual measurements and numerical processing.

    Keywords: sensitivity analysis; anatomical landmarks; knee joint; rotation; ad/abduction

  • Zsolt Čonka ,
    Michal Kolcun ,
    Gyӧrgy Morva :

    Abstract: The Construction of new international power lines is a very expensive and time-consuming task. The use of specialized equipment that can increase the Total Transfer Capacity can replace the need to construct new lines. One such device is a Phase Shift Transformer (PST). By optimal distribution of power flow on transmission lines we could increase TTC on profile. Detailed analysis is presented for Slovakia - Hungary and Slovakia - Czech interconnections in the Central East Europe network. Simulation results with and without PST are used to analyse the impact of PST on the TTC between Slovakia - Hungary and Slovakia - Czech interconnection.

    Keywords: phase shift transformer; total transfer capacity; FACTS

  • Ádám Csapó ,
    György Wersényi ,
    Myounghoon Jeon :

    Abstract: The market penetration of user-centric assistive devices has rapidly increased in the past decades. Growth in computational power, accessibility, and "cognitive" device capabilities have been accompanied by significant reductions in weight, size, and price, as a result of which mobile and wearable equipment are becoming part of our everyday life. In this context, a key focus of development has been on rehabilitation engineering and on developing assistive technologies targeting people with various disabilities, including hearing loss, visual impairments and others. Applications range from simple health monitoring such as sport activity trackers, through medical applications including sensory (e.g. hearing) aids and real-time monitoring of life functions, to task-oriented tools such as navigational devices for the blind. This paper provides an overview of recent trends in software and hardware-based signal processing relevant to the development of wearable assistive solutions.

    Keywords: assistive technology; blind user; haptics; spatial rendering; sonification

  • Komlen Lalović ,
    Nemanja Maček ,
    Milan Milosavljević ,
    Mladen Veinović ,
    Igor Franc ,
    Jelena Lalović ,
    Ivan Tot :

    Abstract: This paper presents a novel approach to noninvasive biometric maternity verification and baby-switching prevention in maternity wards based on dual biometric fingerprint scanner. The proposed system is expected to solve issues that have occurred in many countries regarding stealing or mixing the identities of newborn babies. The solution is based on a device that acquires biometric samples from the mother and her newborn baby right after birth and generates the unique reference of the pair. The same device is used to verify the bound of biometric samples before the mother and the baby are allowed to leave the maternity ward. The privacy of stored templates is provided by cancelable biometrics while the auxiliary data are secured with strong cryptographic protection. The main contribution of the proposed approach is a very high level of proof of maternity for each newborn baby, as well as, the prevention of replacing identities of newborn babies in maternity wards, with a system that can be realized via low cost hardware.

    Keywords: biometrics; fingerprint; minutiae; maternity; identity

  • László Kátai ,
    Tibor Várszegi ,
    István Oldal ,
    László Zsidai :

    Abstract: In this paper the hydrodynamic air flow relations in two adjustable compartment units of the mobile refrigerated container were examined. Analytical solution of the hydrodynamic equations describing the cooling air flow motion is not possible. We applied two possible methods for the solution: (1) - small scale test, (2) - approximate solution of the ordinary differential equations with finite elements simulation. The objective of the performed tests is to define the cooling air flow kinematical conditions, such as air velocity distribution in empty and fully loaded state, testing the shape of the air inlet profile and furthermore to determine the necessity of auxiliary ventilators adaptation. According to the performed test results a proposal to the final development of the cooling and ventilation elements has been made.

    Keywords: cfd analysis; refrigerated container; small scale test; 3D model; FEM

  • Alexander Baklanov ,
    Svetlana Grigoryeva :
    Control of LED Lighting Equipment with Robustness Elements105-119en [823.26 kB - PDF]EPA-02461-00067-0060

    Abstract: This paper presents the results of the study into the control of light-emitting-diode lighting equipment. It also deals with the issues of robustness in the organization of controlling key parameters of a lighting system. An experimental facility for research of using high-power LEDs and controlling them with compensation of uncertainties was developed. The results of that development allows for showing the effectiveness of the use of additional control loops with elements of robust control. Additionaly, there are suggestions to improve systems both of indoor and outdoor led lighting devices of increased power.

    Keywords: robustness; high power LED; control system; controller; Peltier element; SCADA system

  • Mohammadreza Azodinia ,
    András Hajdu :

    Abstract: Due to the extensive use of images in various fields, using effective approaches to retrieve the most related images given, a query image is of great importance. Content-based image retrieval is the approach commonly used to address this issue. The content-based image retrieval systems use many techniques to provide more accurate and comprehensive answers, among which, is relevance feedback. Relevance feedback is used by the system to help it retrieve more relevant images in response to a query. In this paper, we have proposed a novel relevance feedback method that is able to improve the precision of the content-based retrieval systems. The proposed method is based on multi-query relevance feedback, and similarity function refinement.

    Keywords: CBIR image retrieval; CBVIR information retrieval; image database; recommender system

  • Jozsef Nyers :

    Abstract: This article presents a newly designed and realized system for heat recovery from waste water. The waste water is the heat source, the temperature of which is about 44-49 °C. The heat recovery process is performed using a plate heat exchanger and two heat pumps. The mentioned components are serially linked. The heat sink is clean water, which is pumped from a 40 meter deep well and is heated up from 13-14 °C to 50-55 °C. Waste water is cooled down from 44-49 °C to 13-14 °C. The mass flow rate of the clean and waste water is approximately the same. This heat recovery process reaches a significant coefficient of performance (COP) with 6.03-6.5 meaning that 83-85% of the energy demand for heating clean water is provided by the recovery process and electric energy is consumed only for 17-15%. From the aspect of energy efficiency: the plate heat exchanger participates by about 49%, the low temperature heat pump by 30%, the high temperature heat pump by 21% in the heat recovery.

    Keywords: heat recovery; heat pump; waste water; COP; payback period

  • Obrad Stevanović ,
    Dalibor Kekić ,
    Valentin Kónya ,
    Miloš Milenković :

    Abstract: This paper focuses on finding the most suitable number of fire-fighters who will be engaged on special events, such as concerts, sport tournaments, music events or similar events, while at the same time ensuring the number of fire-fighters in a particular fire station for each shift will be enough to ensure the overall social welfare of a community and remain at the lowest possible costs. Due to the risk of fire and other public welfare risks, it is often common fire-fighters are required to be engaged in special events with their duty primarily at those special event locations. Their main task certainly is to protect all people in a community and its assets by quick response in case of an emergency. Consequently, it remains necessary to provide a sufficient number of fire-fighters who will remain at the fire station so that they meet the standard requirements of them during each shift. In cases of temporary absences and permanent attrition in the fire-fighter workforce, sometimes commanders need to use overtime and hiring of additional fire-fighters to satisfy the needs of organizers of special events. In those situations, they also have to think about minimizing total staffing costs and budget restraints. This paper uses linear programming to develop a model for determining the optimal number of fire-fighters to have on staff during additional demands of special events still covering the standard emergency coverage within a community. Also, the aim of this paper is to present a model which will facilitate the decisions of commanders of fire stations when determining the number of fire-fighters required for ordinary and extraordinary activities.

    Keywords: fire-fighter; model; constraints; optimization

  • Tünde Tóth-Téglás ,
    Erika Hlédik ,
    Laura Fónadová :
    An Analysis of Employer Requirements of University Graduates169-188en [539.52 kB - PDF]EPA-02461-00067-0100

    Abstract: It is of equally outstanding importance for university graduates and universities alike to learn what requirements workplaces have of graduates and what knowledge and skills they are expected to have. Previous research in Hungary conducted by GVI MKIK and DPR examined employer and higher education graduate views based on the importance of expected competencies. In our research we focused on understanding employer requirements related to the recruitment of graduates. Therefore, we examined the opinions of companies that assumingly had a conscious strategy for employing graduates, and we carried out comprehensive analyses of the findings of comprehensive research. Our research findings reveal that the large companies surveyed assigned primary importance to competencies ensuring present performance; at the same time, the aspect of competencies enabling future performance also emerged as relevant. It was also analysed in our study to what extent the companies surveyed had different requirements of economic and technical graduates. The research furthermore explored with the help of factor analysis in what ways the respective competency requirements were interrelated in the employers’ approach. Although our research was conducted among Hungarian companies exclusively, we believe that the findings related to the role of corporate size and field of specialisation may generate conclusions of interest for research carried out in other countries as well.

    Keywords: workplace requirements; competencies; skill requirements; graduate recruitment process

  • Georgiana Simion ,
    Ciprian David ,
    Vasile Gui ,
    Cătălin-Daniel Căleanu :

    Abstract: The widespread deployment of Natural User Interface (NUI) systems in smart terminals such as phones, tablets and TV sets has heightened the need for robust multi-touch, speech or facial recognition solutions. Air gestures recognition represents one of the most appealing technologies in the field. This work proposes a fingertip-based approach for hand gesture recognition. The novelty in the proposed system is the tracking principle, where an improved version of the multi-scale mode filtering (MSMF) algorithm is used, and in the classification step, where the proposed set of geometric features provides high discriminative capabilities. Empirically, we conducted an experimental study involving hand gesture recognition - on gestures performed by multiple persons against a variety of backgrounds - in which our approach achieved a global recognition rate of 95.66%.

    Keywords: fingertip detection; hand gesture recognition; image classification; image edge detection; object recognition

  • József Menyhárt ,
    Róbert Szabolcsi :
    Support Vector Machine and Fuzzy Logic205-220en [758.40 kB - PDF]EPA-02461-00067-0120

    Abstract: The article gives a short description of the history of the Support Vector Machine (SVM) method and fuzzy logic and their main parameters. It describes how SVM can be used for classification and regression calculation. In addition, it includes the description of the fuzzy logic and the three main defuzzification methods. Examples will be given to show simultaneous use of the two main Support Vector Machine-methods. It ends with the authors’ description of the new possibilites for the use of the SVM and fuzzy logic in evaluation of the parameter deviation in the batteries of electric vehicles as well as those of robots.

    Keywords: SVM; classification; regression; fuzzy

  • Filip Jovanović ,
    Nenad Milijić ,
    Makedonka Dimitrova ,
    Ivan Mihajlović :

    Abstract: The paper explores the impact of the main elements of the strategic investment projects management process in South East Europe (SEE), on achieving project objectives. The impact of different projects elements on the project’s risk management process was also addressed. The initial hypotheses are based on literature review in the field. The proposed hypotheses were tested by the SEM (Structural Equation Modeling) methodology on a sample of 311 strategic investment projects in Serbia, Bosnia and Herzegovina as well as Macedonia. The strategic projects were analyzed in companies across various business sectors thus the obtained results represent a benchmark of risk factors’ significance according to the project team members and managers. The benchmarking of risk factors significance was conducted by using the PROMETHEE – GAIA methodology. The results verify the adequacy of the hypothetical framework.

    Keywords: risk management; strategic investment projects; project objectives