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Acta polytechnica HungaricaVolume 8, Issue No. 5 (2011.)


  • András Róka ,
    Ákos Zarándy :

    Abstract: In this paper, we present a bio-inspired computational framework for the hypothetical cooperation of the ocular drift and a place coding neural circuitry. The proposed bio-inspired mechanism can provide an explanation for the ability of primate vernier hyperacuity. Our starting point is a spatiotemporal model of the primate retinal P and M ganglion cells. First we show that in the central retina, the drift-induced movement moves the stimuli of preferred spatial frequency with a velocity that is optimal for P cells and almost "invisible" for the movement-sensitive M cells. Secondly, based on a presumed analogy between the owl's auditory system and a primate visual system we present a theory that visual hyperacuity can be originated to the detection of time delays between neural firing patterns. Third, we propose a possible neural model for the place coding circuitry. Our new theory may serve suggestions for further research.

    Keywords: ocular drift; place coding circuitry; hyperacuity; computational model

  • O. Tolga Pusatli ,
    Sanjay Misra :

    Abstract: An empirical study for evaluating the proper implementation of measurement/metric programs in software companies in one area of Turkey is presented. The research questions are discussed and validated with the help of senior software managers (more than 15 years’ experience) and then used for interviewing a variety of medium and small scale software companies in Ankara. Observations show that there is a common reluctance/lack of interest in utilizing measurements/metrics despite the fact that they are well known in the industry. A side product of this research is that internationally recognized standards such as ISO and CMMI are pursued if they are a part of project/job requirements; without these requirements, introducing those standards to the companies remains as a long-term target to increase quality.

    Keywords: metric; measurement; small-medium size enterprise; ISO; CMMI

  • András Baczoni ,
    Ferenc Molnár :

    Abstract: Zinc-rich primers (ZRPs) are widely used coatings for corrosion control on steel surfaces. Usually ZRPs use high zinc concentration in the paint and a little amount of organic resin used as a binder. Commonly, two fundamental protection mechanisms operating in ZRPs can be recognised, namely the galvanic protection and the barrier effect. The high zinc content can secure cathodic protection to the base metal, and the zinc corrosion products can make the barrier effect. In this research study, the cathodic corrosion protection capabilities of zinc rich alkyd primers prepared with different spherical zinc dust volume concentrations (0-20-40-60-80% by weight) are tested. The mechanical, electrochemical and dielectric properties are measured in order to find a correlation between these and the protection capabilities of the coating.

    Keywords: zinc-rich primers; thermodielectric spectroscopy; cathodic protection; alkyd resin

  • Ahmet Akbulut ,
    Tugrul Adiguzel ,
    Asim Egemen Yilmaz :

    Abstract: In this study, pronunciation ambiguity in Turkish is considered. A syllable-based ambiguity detection/resolution framework is proposed for Turkish text-to-speech synthesis applications. For this purpose, first the pronunciation ambiguity cases are identified. Such cases are classified into 7 main groups. Statistical analysis on the occurrence rate of these main groups is performed by means of the examination of meaningful Turkish texts. This first level analysis shows that especially the syllables ending with vowels (particularly with a, e and i), which are potential ambiguity sources, have significant occurrence rates. Next, the granularity of the frequency analysis is escalated to distinct syllable level. For the sofar- identified 154 exceptional syllables, the occurrence rates are computed. The results of this study will constitute a major baseline for pronunciation ambiguity detection in Turkish. The resolution of these ambiguous cases will certainly require a large lexicon. The results will also serve as a guideline for the prioritization of data inclusion to such a lexicon (i.e. lexicon enrichment) for rapid coverage. Our distinct syllable level analysis results show that by inclusion of all the words having the 100 most frequent exceptional syllables, it is possible to resolve 99% of pronunciation ambiguities in Turkish. To our belief, the findings of this study might also be applicable and useful for other languages.

    Keywords: Text-to-speech synthesis; natural language processing; grapheme-to-phoneme conversion; less studied languages; pronunciation ambiguity

  • Petar Čisar ,
    Sanja Maravić Čisar :
    Optimization Methods of EWMA Statistics73-87en [682.95 kB - PDF]EPA-02461-00031-0050

    Abstract: Many intrusions which attempt to compromise the security of computer and network systems manifest themselves in changes in the intensity of events. Because of the ability of exponentially weighted moving average (EWMA) statistics to monitor the rate of occurrences of events based on their intensity, this technique is appropriate for implementation in control limits based algorithms. The research has shown that the usual application of this algorithm on computer network traffic, as applied in industrial processes, does not provide acceptable results. The paper also gives a review of possible optimization methods.

    Keywords: intrusion detection; EWMA; control limits; optimization; autocorrelation; ARL

  • Gábor Bódai ,
    Tibor Boda :

    Abstract: Parameter identification methods available in the literature are based on complex and time-consuming experiments, such as dynamic-mechanical-thermal-analysis (DMTA), stress relaxation tests, etc. To the authors’ best knowledge there is no method in the literature which would be able to identify large-strain viscoelastic parameters of generalized Maxwell-model from simple constant strain rate tensile tests. In this paper, the authors present a new method which is based on two tensile tests performed at different strain rates. Firstly, a series of experiments (tensile tests, stress relaxation tests) is carried out on standard isoprene rubber specimens and then analytical calculations as well as finite element simulations on the basis of identified material parameters are performed. These computations prove the applicability of the method. Although the proposed method is presented for uniaxial tension, it is fully applicable to other load types, such as biaxial tension, simple shear, and planar shear. Additionally, it can be generalized for other spring-dashpot models.

    Keywords: viscoelasticity; parameter identification; tensile test; rubber; finite element analysis

  • Sanjay Misra :
    Evaluation Criteria for Object-oriented Metrics 109-136en [553.99 kB - PDF]EPA-02461-00031-0070

    Abstract: In this paper an evaluation model for object-oriented (OO) metrics is proposed. We have evaluated the existing evaluation criteria for OO metrics, and based on the observations, a model is proposed which tries to cover most of the features for the evaluation of OO metrics. The model is validated by applying it to existing OO metrics. In contrast to the other existing criteria, the proposed model is simple in implementation and includes the practical and important aspects of evaluation; hence it suitable to evaluate and validate any OO complexity metric.

    Keywords: Evaluation Criteria; Measurement; Verification; OO Metrics; Weyuker’s Property; language independency; additive nature of metrics

  • Cecília Sik-Lányi ,
    János Schanda :
    Analysing the Colours of the Virtual Reality Museums’ Picture137-150en [701.98 kB - PDF]EPA-02461-00031-0080

    Abstract: Showing the works of famous artists to students is a fundamental task in order to teach fine art history. Images found on the Internet are a major source for such pictures that can replace older albums of fine art collections. The question arises as to how far one can rely on the colour quality of the images displayed on the Internet, and as to whether it is worthwhile to put much effort into the colour correct presentation on the receiving side. Images have been collected both from museums’ publications and from the Internet, and some critical areas of the images have been colorimetrically evaluated. From these comparisons one can conclude that at present the distributors of the images do not pay enough attention to putting colour-correct images onto the Internet.

    Keywords: colour; virtual reality; museum

  • Enikő Kelemen-Erdős :

    Abstract: This paper analyses the liberalization procedure of the passenger and freight railway transport market in the Visegrád states. The paper applies macro and micro environment analysis to demonstrate the situation of these post-communist countries and introduces the regulatory impact on the railway market supply while concentrating on intra-modal competition. The aim of the paper is to highlight how railway liberalization has changed the shrinking railway market in order to define a strategic policy intervention, with the express purpose of increasing the competitiveness of railway transport and solving efficiency problems. The paper introduces the rate of railway market attractiveness (RAMATE rate) in order to compare the attractiveness of the different railway markets of the European Union for new entrants and the degree of deregulation.

    Keywords: railways; market liberalization; market attractiveness; Visegrád States; European Union

  • Rakesh M. Patel ,
    Gunamani Deheri ,
    Himanshu C Patel :

    Abstract: An endeavor has been made to investigate the performance of a magnetic fluid based squeeze film between rough circular plates while the upper plate has a porous facing of variable porous matrix thickness. The bearing surfaces are transversely rough. The random roughness of the bearing surfaces is characterized by a random variable with non-zero mean, variance and skewness. The associated Reynolds’ equation is stochastically averaged with respect to the random roughness parameter and is solved with appropriate boundary conditions. The results for bearing performance characteristics such as pressure, load carrying capacity and response time for different values of mean, standard deviation and measure of symmetry are numerically computed and presented graphically. First of all it is observed that these performance characteristics increase with the increasing magnetization parameter thereby, suggesting that the performance of the bearing with magnetic fluid lubricant is better than that with the conventional lubricant. It is noticed that the bearing suffers owing to transverse surface roughness. However, the negatively skewed roughness tends to increase the load carrying capacity. Moreover, there is a very significant observation that with a proper selection of the thickness ratio parameter a magnetic fluid based squeeze film bearing with variable porous matrix thickness in the case of negatively skewed roughness can be made to perform considerably better than that of a conventional porous bearing with an uniform porous matrix thickness working with a conventional lubricant. In addition, this article makes it clear that by choosing properly the thickness ratio parameter and the strength of the magnetic field, the adverse impact induced by roughness on the bearing system can be minimized in the case of negatively skewed roughness especially when negative variance occurs. Thus, this study makes it mandatory to account for roughness while designing the bearing system.

    Keywords: magnetic fluid; squeeze film; transverse roughness; Reynolds’ equation; variable film thickness; load carrying capacity

  • Abderrahim Belmadani ,
    Lahouaria Benasla ,
    Mostefa Rahli :

    Abstract: In this paper, we investigate the effect of the injection of wind farm energy in the western Algerian electrical power system on Dynamic Economic Dispatch (DED). DED is solved by Harmony Search algorithm (HS). HS is a newly-developed meta-heuristic algorithm that uses a stochastic random search. It is simple in concept, few in parameters and easy in implementation. The simulations are realized by considering first the western Algerian power system as it is (WA: 2003 data), then the western Algerian electrical power system with the injection of wind farm energy (Western Algerian power system + Wind energy WAW). The results are compared in production cost and harmful emissions (CO2). After a theoretical introduction of the problem formulation and the harmony search algorithm, a description of the site and the wind farm is presented, followed by a discussion of the simulation results.

    Keywords: optimization; harmony search; dynamic economic dispatch; wind power; CO2 emission

  • Károly Hercegfi :
    Heart Rate Variability Monitoring during Human-Computer Interaction205-224en [683.17 kB - PDF]EPA-02461-00031-0120

    Abstract: This paper outlines a Heart Rate Variability (HRV)-based method applicable to Human-Computer Interaction (HCI) researches. After a brief overview of various psychophysiology-based empirical techniques (mainly focusing on the mental effort approach), a recent research is shown. The paper presents new results of a short, basic series of experiments, attempting to explore the boundaries of the temporal resolution of the method. The applied INTERFACE methodology is based on the simultaneous assessment of HRV and other data. The results raise hope that this methodology is potentially capable of exploring mechanisms underlying practical usability issues and identifying quality attributes of software elements – over the previously developed HRV-based methods – with a temporal resolution of only a few seconds.

    Keywords: Human-Computer Interaction (HCI); software usability testing and evaluation; empirical methods; Heart Rate Variability (HRV)