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Acta polytechnica HungaricaVolume 6, Issue No. 5 (2009.)


Tematikus cím:Special Issue in Honor of the 60th Birthday of Professor Imre J. Rudas
  • János Fodor :
    Foreword5-6en [71.62 kB - PDF]EPA-02461-00021-0010
  • Wilfried Elmenreich ,
    Tobias Ibounig ,
    István Fehérvári :
    Robustness versus Performance in Sorting and Tournament Algorithms7-18en [424.08 kB - PDF]EPA-02461-00021-0020

    Abstract: In this paper we analyze the robustness of sorting and tournament algorithms against faulty comparisons. Sorting algorithms are differently affected by faulty comparisons depending on how comparison errors can affect the overall result. In general, there exists a tradeoff between the number of comparisons and the accuracy of the result, but some algorithms like Merge Sort are Pareto-dominant over others. For applications, where the accuracy of the top rankings is of higher importance than the lower rankings, tournament algorithms such as the Swiss System are an option. Additionally, we propose a new tournament algorithm named Iterated Knockout Systems which is less exact but more efficient than the Swiss Systems.

    Keywords: sorting algorithms, robustness, tournaments, iterated knockout system

  • József Dombi :
    Pliant Arithmetics and Pliant Arithmetic Operations19-49en [326.36 kB - PDF]EPA-02461-00021-0030

    Abstract: Fuzzy arithmetic based α -cuts, where the result of the α -cuts represent an interval. The arithmetic can be understand as an interval arithmetic of the α -cuts. Instead of dealing with intervals we are dealing with left and right hand sided soft inequalities which define the interval. We offer a new calculation procedure of arithmetics, when these soft inequalities meet certain properties (i.e. strict monotonously increasing function represent the inequality). We show that the result of linear combinations of linear is also linear and the linear combination of sigmoid is also sigmoid function (i.e. they are closed under linear combination). We give the result of other operation, too. The soft inequalities define an interval by using proper conjunctive and disjunctive operator. We give such operations, too. Keywords: fuzzy arithmetic, sigmoid function, triangular membership function, membership function, distending function


  • Ngoc Dung Vuong ,
    Marcelo H. Ang Jr. :
    Dynamic Model Identification for Industrial Robots51-68en [398.26 kB - PDF]EPA-02461-00021-0040

    Abstract: In this paper, a systematic procedure for identifying the dynamics of industrial robots is presented. Since joint friction can be highly nonlinearwith time varying characteristics in the low speed region,a simple and yet effective scheme has been used to identify the boundary velocity that separates this “dynamic” friction region from its static region. The robot’s dynamic model is then identified in this static region, where the nonlinnear friction model is reduced to the linear-in-parameter form. To overcome the drawbacks of the least squares estimator, which does not take in any constraints, a nonlinear optimization problem is formulated to guarantee the physical feasibility of the identified parameters. The proposed procedure has been demonstrated on the first four links of the Mitsubishi PA10 manipulator, an improved dynamic model was obtained and the the effectiveness of the proposed identification procedure is demonstrated.

    Keywords: Dynamic Modeling, Model Identification, Friction Models, Model-based Control

  • Hannu Jaakkola :
    Towards a Globalized Software Industry69-84en [144.66 kB - PDF]EPA-02461-00021-0050

    Abstract: Software Engineering (SE) represents a remarkable share of the Information and Communication Technology (ICT) industry, which is an important feature of modern welldeveloped societies. Its importance can be seen on two levels: the industry itself and its indirect consequences for other industries. Although the SE industry represents a reasonably small share of employment (in the home country of the author, 2-3%), the indirect effects raise its economic importance to a much higher level. The role of the ICT industry is also used as one of the Information Society (IS) metrics in country comparisons. One of the leading trends of modern SE is globalization: employees represent different national cultures and the organizations are distributed across several countries. This paper opens the discussion on the topics worth considering when making globalization decisions. The basic hypothesis is that decisions are mainly based on economic factors. The organizational and cultural factors connected to these decisions are not well understood. At the beginning of the paper some background is introduced and the results of related studies are listed. The paper introduces a framework that is useful in planning the globalization of an organization. This paper focuses on the Finnish software industry; however, the same principles are applicable independent of the country or nation.

    Keywords: cross-cultural, multicultural, software engineering (SE), cultural sensitivity, global software development, information and communication technology (ICT), globalization, global software development (GSD)

  • Tamás Réti ,
    István László :
    On the Combinatorial Characterization of Fullerene Graphs 85-93en [214.37 kB - PDF]EPA-02461-00021-0060

    Abstract: In order to characterize and classify quantitatively the local topological structure of traditional fullerene graphs a new method has been developed. The concept is based on the introduction of a finite set of novel topological invarians called pentagon arm indices. The definition of pentagon arm indices is similar to that of well known pentagon adjacency indices, and their common features is that both of them characterize the local topological neighborhood of pentagons included in traditional fullerenes. It will be demonstrated that pentagon adjacency indices and pentagon arm indices together can be successfully applicable for preselecting the stable candidates of lower fullerene isomers Cn with n≤70.

    Keywords: graph invariant, pentagon-neighbor signature, prediction of fullerene stability

  • Musrrat Ali ,
    Millie Pant ,
    Ajith Abraham :
    Simplex Differential Evolution95-115en [623.79 kB - PDF]EPA-02461-00021-0070

    Abstract: Differential evolution (DE) algorithms are commonly used metaheuristics for global optimization, but there has been very little research done on the generation of their initial population. The selection of the initial population in a population-based heuristic optimization method is important, since it affects the search for several iterations and often has an influence on the final solution. If no a priori information about the optima is available, the initial population is often selected randomly using pseudorandom numbers. In this paper, we have investigated the effect of generating the initial population without using the conventional methods like computer generated random numbers or quasi random sequences. We have applied non linear simplex method in conjugation of pseudorandom numbers to generate initial population for DE. Proposed algorithm is named as NSDE (using non linear simplex method), is tested on a set of 20 benchmark problems with box constraints, taken from literature and the numerical results are compared with results obtained by traditional DE and opposition based DE (ODE). Numerical results show that the proposed scheme considered by us for generating the random numbers significantly improves the performance of DE in terms of convergence rate and average CPU time.

    Keywords: Stochastic optimization, differential evolution, crossover, initial population, random numbers