a borítólapra  Súgó epa Copyright 
Acta polytechnica HungaricaVolume 11, Issue No. 3 (2014.)


  • Tamás Galli ,
    Francisco Chiclana ,
    Jenny Carter ,
    Helge Janicke :

    Abstract: Execution tracing and logging significantly influence the time spent on localizing software errors; consequently, they have essential impact on maintainability. Moreover, in certain situations these tools are the best suited instruments to analyse the behaviour of distributed, multithreaded or embedded applications. In spite of this, software product quality frameworks do not include execution tracing or logging as a quality property. In this paper we examine the extension possibilities of the present software product quality frameworks to accommodate execution tracing. In addition, the scope of the investigation includes facilities of the frameworks to address the uncertainty involved in quality measurements.

    Keywords: quality frameworks; execution tracing; logging; uncertainty

  • Santhosh P. Mathew ,
    Valentina E. Balas ,
    Zachariah K. P. ,
    Philip Samuel :

    Abstract: Content Based Image Retrieval (CBIR) is used to effectively retrieve required images from fairly large databases. CBIR extracts images that are relevant to the given query image, based on the features extracted from the contents of the image. Most of the CBIR systems available in the literature are not rotation and scale invariant. Retrieval efficiency is also poor. In this paper, shape features are extracted from the database images and the same are polar raster scanned into specified intervals in both radius and angle, using the proposed Polar Raster Edge Sampling Signature (PRESS) algorithm. Counts of edge points lying in these bins are stored in the feature library. When a query image passed on to the system, the features are extracted in the similar fashion. Subse-quently, similarity measure is performed between the query image features and the data-base image features based on Euclidian Distance similarity measure and the database images that are relevant to the given query image are retrieved. PRESS algorithm has been successfully implemented and tested in a CBIR System developed by us. This technique pre-serves rotation and scale invariance. It is evaluated by querying different images. The retrieval efficiency is also evaluated by determining precision-recall values for the retrieval results.

    Keywords: image retrieval; polar raster edge sampling signature; image segmentation; feature extraction; K-means clustering; Canny algorithm

  • Tibor Poós ,
    Mária Örvös ,
    Miklós Horváth :
    Thermal Dewatering of Waste Sludge in an Agitated Drum Dryer37-50en [1.03 MB - PDF]EPA-02461-00049-0030

    Abstract: This study presents experiences of drying waste sludge in an agitated drum dryer. Measurements were performed on an agitated drum dryer apparatus equipped with up-to-date instrumentation. As waste sludge is prone to adhesion and balling, it is important to identify the conditions appropriate for drying. Different cases were examined; during measurements, the rotational speed of the agitator, the quantity and moisture content of the sludge fed in as well as the temperature of the wall and the drying gas were changed. The measurement data were used to represent the temperatures characteristic of drying and the mass changes of the product. Volumetric mass transfer coefficients were determined from the measurements and a modified Sherwood number was derived from them. The dimensionless Sh’-Re’ equation enables to dimension agitated drum dryers.

    Keywords: agitated drum dryer; Sherwood number; volumetric mass transfer coefficient; waste sludge drying

  • Okan Bingol ,
    Kubilay Tasdelen ,
    Zekeriya Keskin ,
    Yunus Emre Kocaturk :
    Web-based Smart Home Automation: PLC-controlled Implementation51-63en [805.42 kB - PDF]EPA-02461-00049-0040

    Abstract: The most important source of motivation in continuity of technological developments is to upgrade human living standards. The technological development provides and increases human-beings’ safety and comfort directly and indirectly. Developing technologies for this purpose directly affects the life standards by means of smart home systems design. It is possible to classify smart home systems into two as local and remote. In this study, a smart home automation system design was carried out by using Delta DVP28SV model PLC (Programmable Logic Controller). Smart home system can be controlled in two different ways either by any internet-connected device or an operator panel assembled on PLC. Control of the ventilation, lighting and security units in the smart home were carried out. Instantaneous states and variations of the smart home system which is feedback based are monitored and can be changed from the user interface prepared with the C# programming language. Unusual circumstances occurred in security units have been reported to the user with SMS (Short Message Service).

    Keywords: Home automation; PLC; Remote control; Smart home

  • Anna Göncz ,
    Lajos Göncz ,
    Jasmina Pekić :

    Abstract: This paper investigates the extent to which it is possible to predict the influence of personality traits of students of computer sciences (i.e. natural and technical sciences, n = 188) and of humanities (i.e. social and humanistic sciences, n = 250) on their perception of a good teacher. The five-factor model of personality provided the theoretical framework of the research, in which personality traits are classified into five domains: neuroticism, extraversion, openness to experience, agreeableness and conscientiousness. Statistical analysis on the total sample (n = 443) at the domain level showed that about 20% of the criteria variance (assessment of personality characteristics ascribed to a good teacher using the Big Five Inventory questionnaire) was attributable to the predictors (self-assessment of personality dimensions using the same questionnaire). For the analysis of individual questionnaire items, the common variance was 15%. Self-reports of openness, agreeableness and neuroticism were better predictors of evaluations of a good teacher than self-reports of extraversion and conscientiousness. The basic expectation of a good teacher was openness to experience, and the aspects of agreeableness and neuroticism that provide good interpersonal relations. Students of social and humanistic sciences favoured more extravert, open and conscientious teachers than natural and technical sciences students. The prediction of good teacher expectations (on the basis of personality characteristics) was more successful with the students of natural and technical sciences than with social and humanistic sciences students.

    Keywords: personality traits of students; assessment of teachers; five-factor model of personality

  • Károly Széll ,
    Péter Korondi :

    Abstract: The sliding mode control of Variable Structure Systems has a unique role in control theories. First, the exact mathematical treatment represents numerous interesting challenges for the mathematicians. Secondly, in many cases it can be relatively easy to apply without a deeper understanding of its strong mathematical background and is therefore widely used in the field of power electronics. This paper is intended to constitute a bridge between the exact mathematical description and the engineering applications. The paper presents a practical application of the theory of differential equation with discontinuous right hand side proposed by Filippov for an uninterruptible power supply. Theoretical solutions, system equations, and experimental results are presented.

    Keywords: sliding mode control; variable structure system; uninterruptable power supply

  • Lakhdar Bessissa ,
    Larbi Boukezzi ,
    Djillali Mahi :

    Abstract: Given the non-linearity of changes in the dielectric and mechanical properties of insulation, it is difficult to find neither a theoretical nor an experimental model for the aging mechanism. Hence, the need to model the evolution of mechanical properties of the XLPE material under thermal aging using new methods is necessary. The use of fuzzy logic is one of these methods and presents an original idea in high voltage prediction problems. Several factors were considered, namely the aging time and the level of applied temperature. The study of the impact of these parameters on the quality of the fuzzy algorithm is carried out. The characteristics of the modelling function (trapezoidal or triangular) and the number of membership functions partitions was also taken into consideration. The obtained results were encouraging. It has been proved that fuzzy logic is a powerful tool that can be used in predicting the properties of insulation. Furthermore, the analytical findings were in good agreement with the experimental results with an acceptable error margin.

    Keywords: Thermal aging; Crosslinked polyethylene (XLPE); Fuzzy logic; Fuzzy Inference System (FIS); Number of partitions

  • Mária Dománková ,
    Edina Kocsisová ,
    Ivan Slatkovský ,
    Peter Pinke :

    Abstract: The process of the secondary phases precipitation controls the mechanical and physical properties of the stainless steels. The process of precipitation and its influence on corrosion resistance was analysed in the experimental steel AISI 316. The corrosion test ASTM A 262 practice A was used for evaluation of the experimental steel to intergranular corrosion. Results showed that the solution-annealed samples (1100°C/1h – followed by water quenching) did not present susceptibility to intergranular corrosion. The heat treatment in the range from 500 to 900°C resulted in susceptibility to intergranular attack. Precipitation of carbide M23C6 accelerates sensitisation of the experimental steel. Increasing of holding time cased precipitation -phase and carbide M6C, which were detected at grain boundaries. Transmission electron microscopy was used for identification of particles at the grain boundaries, measurement of their size and studied of their morphology.

    Keywords: austenitic stainless steel; precipitation; sensitisation; intergranular corrosion

  • Jozsef Nyers ,
    Laszlo Garbai ,
    Arpad Nyers :

    Abstract: this article aims to investigate the performance of the heat pump’s condenser and functionality, suitability of the steady-state mode mathematical model and the used numerical method. The heat transferred through the condenser is the performance of the condenser. The condenser is plate exchanger. The refrigerant is R 134a and the heated medium is water. This wide-range study investigates the condenser's performance depending on four independent external variables. The independent external variables are: inlet temperature of the refrigerant, refrigerant mass flow rate, the water inlet temperature and the water mass flow rate.The investigation is carried out by using a steady state mode mathematical model with lumped parameter. The model consists of two parts. Part one describes mathematically the cooling of the superheated vapor, while the second part describes the condensation itself. The physical model is simple, only the plate condenser and the input, output parameters are included. This article does not take into consideration the compressor and circulating pump model. That remains the subject of future investigation. The results can be represented in three-dimensional graphics. For example, it shows the changes of heat transfer in the condenser depending on the refrigerant mass flow rate and the water mass flow rate.

    Keywords: condenser; heat pump; circulator pump; performance; mathematical model; mass flow rate; efficiency

  • Zoran Krupka ,
    Durdana Ozretic-Dosen ,
    Jozo Previsic :

    Abstract: The aim of this paper is to investigate the impact of perceived brand name origin and perceived country of origin (COO) on fashion brand’s perceived luxury. Results of exploratory research indicate that perceived brand name origin has a strong impact on perceived luxury, and subsequent willingness to pay a price premium, regardless whether the brand is fictional and only sounds as if originated from a certain country (e.g. “Italian sounding brand”) or is a real brand. Results also indicate that by naming fashion brands to have a desirable (e.g. Italian) tone, potential negative impacts of real COO and even a country of manufacture (COM) could be mitigated.

    Keywords: Brand Name Origin; Luxury Fashion Brands; Country of Origin; Fashion Marketing

  • Tamás Portik ,
    László Pokorádi :

    Abstract: Nowadays, it is indispensible to take into consider the risk in modern technical management especially in hydraulic systems under different circumstances. The reliability of a hydraulic system is a well investigated area by researchers because of system damages or crash down can cause cost losses, human injuries or death. If the hydraulic system gives back imprecise or vague data and the reports of expert given by linguistic variables during the inspection then the risk assessment must be calculated with fuzzy mathematics. In this paper, the authors propose a modified fuzzy rule based risk assessment method for the risk assessment of hydraulic systems. The difference between the proposed and the original methods is the defuzzification sub process only. This defuzzification sub process is called Summarized Defuzzification (SDF).

    Keywords: hydraulic system, fuzzy risk assessment, Summarized Defuzzification

  • Imre Petkovics ,
    Pere Tumbas ,
    Predrag Matković ,
    Zoltan Baracskai :

    Abstract: Implementation of the business process management concept at universities has crucially contributed to abandoning traditional and introducing innovative processes in recent years. In particular, information technologies serve as not only means of automation but also a method of altering the approach to conducting business operations. Information technologies either facilitate or hinder the use faster, better and more cost-effective solutions for implementing business processes. This article analyses the possibility of supporting business processes in universities’ external collaboration with cloud computing technologies, and their influence on the process’ input-output data quality dimensions.

    Keywords: cloud computing; business process; innovative university

  • Sándor Molnár :
    On the Reachability of Linear Time Varying Systems201-217en [228.91 kB - PDF]EPA-02461-00049-0130

    Abstract: In this paper system properties of generalized linear time varying (LTV) systems are discussed where, in addition to the control, its certain derivatives also appear both in the dynamics and the observation equation. Developing an adequate version of the Cauchy formula, a necessary and suffiecient condition for complete reachability of generalized LTV systems is obtained in terms of a generalized Gram matrix. Starting from the expansion of coefficient functions in the corresponding Lie algebra basis, we derive an appropriate condition of persistent excitation. The latter leeds to a general condition of complete reachability in terms of quasi-polynomials of the solution of the Wei-Norman equation and differential polynomials of the coefficient functions of the generalized LTV system. Also applying the well-known duality theory of LTV systems, other basic system properties such as controllability, reconstructability and observability can be also treated

    Keywords: Controllability and reachability; Differential algebra; Linear time varying systems; Matrix Lie algebra, persistent excitation

  • Chiheb Ben Regaya ,
    Abderrahmen Zaafouri ,
    Abdelkader Chaari :

    Abstract: In this paper, the speed of the induction machine is controlled by a variable structure controller. To eliminate speed sensor we use a sliding mode observer based on fuzzy logic “FSMSO”. The control algorithm and observation is emphasized by simulation tests and it is comapred with the classical sliding mode speed observer”SMSO”. Analysis of the results shows the characteristic robustness to disturbances of the load and the speed variation for the FSMSO than SMSO.

    Keywords: induction motor; fuzzy sliding mode speed observer; sliding mode control; sliding mode speed observer; vector control

  • Fuat Alarçin ,
    Hakan Demirel ,
    M. Ertugrul Su ,
    Ahmet Yurtseven :

    Abstract: The aim of this study is to decrease a fishing boat’s roll motion, which is adversely affected by disturbing hydrodynamic forces, by applying fin roll stabilizer. It is ensured that roll motion with nonlinear damping and restoring moment coefficients reaches the desired level by means of classical PID and modified PID algorithms. By Lyapunov’s direct method, the key issue- stability which is needed during the course of sailing was examined considering initial conditions, and it was realized that the system was generally stable. Besides, NACA 0015 model was utilized for the fin roll stabilizer, and flow analysis was conducted by CFD method. According to the simulation results, when the same gains were practiced, modified PID controller algorithms were rather more efficient than conventional PID in the roll fin stabilizer system.

    Keywords: modified PID control; fin stabilizer; Lyapunov direct method