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Acta polytechnica HungaricaVolume 15, Issue No. 2. (2018.)


  • László Horváth ,
    Imre J. Rudas :
    Information Content Driven Model for Virtual Engineering Space7-32en [445.17 kB - PDF]EPA-02461-00079-0010

    Abstract: Engineering practice is increasingly relied upon virtual technologies. Recent virtual solutions ensure integration of all engineering activities using system level computer representation of complex multidisciplinary engineering product. The authors have provided research results in developing strategies for leading engineering virtual technology, for more than twenty years. They analyzed paradigm shifts on the way to present virtual engineering systems and organized their work around their formerly published concept of Virtual Engineering Space (VES). These were preliminaries of the reported work in this paper. New method is introduced for structuring and representation of active driving knowledge content background (KCB) in engineering model. The purpose of KCB is to drive entity generation in the KCB extended industrial engineering model of a product system. This paper introduces handling contextual initiatives and the application of them to define KCB structure for the generation of self-adaptive generic objects explaining role and structure of information content, as well as, the related model driving mechanism. Appropriately organized and configured engineering models offer a means for integration of engineering model based industrial, research and higher education applications in common VES. Recent industrial professional engineering modeling systems offer capabilities for implementation of KCB and application relevant configuration, of modeling capabilities for disciplines and human roles.

    Keywords: virtual engineering space; system level product model; self-adaptive product object model; knowledge content background; multipurpose virtual engineering space

  • Aleksandra Vukmirović ,
    Zoltán Rajnai ,
    Miroslav Radojičić ,
    Jovanka Vukmirović ,
    Marina Jovanović Milenković :

    Abstract: Infrastructural model presented and developed in this paper represents a pillar for medical research and has a profound implication in the future of healthcare. The roposed model is based on Big Data concept that refers to technologies and techniques that consist of diverse data that changes rapidly and is too big and therefore cannot be efficiently processed by traditional computer technology and infrastructure. Components of this model are described in detail. In addition, this paper illustrates advantages, limitations, examples and recommendations for the use of Big Data in the healthcare system.

    Keywords: Big Data; model; healthcare; Cloud technologies

  • Péter Szántó ,
    Béla Fehér :
    Hierarchical Histogram-based Median Filter for GPUs49-68en [863.69 kB - PDF]EPA-02461-00079-0030

    Abstract: Median filtering is a widely used non-linear noise-filtering algorithm, which can efficiently remove salt and pepper noise while it preserves the edges of the objects. Unlike linear filters, which use multiply-and-accumulate operation, median filter sorts the input elements and selects the median of them. This makes it computationally more intensive and less straightforward to implement. This paper describes several algorithms which could be used on parallel architectures and propose a histogram based algorithm which can be efficiently executed on GPUs, resulting in the fastest known algorithm for medium sized filter windows. The paper also presents an optimized sorting network based implementation, which outperforms previous solutions for smaller filter window sizes.

    Keywords: median; filter; GPGPU; CUDA; SIMD

  • Norbert Ádám ,
    Anton Baláľ ,
    Emília Pietriková ,
    Eva Chovancová ,
    Peter Feciµak :

    Abstract: Artificial neural networks are massively parallel systems containing large amounts of simple computing elements. Therefore, it is natural to try to implement them using parallel computing architectures. This paper deals with an implementation of a three layer multilayer perceptron artificial neural network. It summarises the impact of using various forms of data representation on the performance of the hardware implementation - a Kintex-7 XC7K325T-2FFG900C FPGA chip on a Xilinx Kintex KC705 board.

    Keywords: fixed-point; floating-point; mlp; neural network; residue number system

  • Vahid Farrokhi ,
    László Pokorádi ,
    Sahar Bouini :

    Abstract: In the past, decisions were made by senior management in organizations and they were based solely on personal experience, leading to increased risk in decision making. Nowadays, however, most companies are moving towards Business Intelligence (BI) systems. It is estimated that technology budgets dedicated to Business Intelligence in 2006, increased from $ 14 to $ 20 billion. Experiments have shown that the probability of failure in BI projects is high and evaluation before the start of implementation is important because if the company is not assessed, the implementation of BI projects can cause a waste of time and resources and the company will not achieve expected profits. The aim of this paper is to provide a method to evaluate the key factors for the successful implementation of BI projects and to determine the organization’s index of assessing readiness before the implementation of BI projects. A series of technical and organizational key factors for the successful implementation of BI have been proposed in various literatures. These key factors will be evaluational ones for an organization. We apply a combination of Interpretive Structural Modeling (ISM) and Graph Theory and Matrix Approach (GTMA) on the factors to earn an indicator for evaluating the organization's readiness for implementing a BI project. We applied this method in two organizations for comparing and determined the organizations’ readiness before the implementation of BI and found it to be very effective.

    Keywords: Business Intelligence; Readiness Evaluation; Critical Success Factors; Interpretive Structural Modeling; Graph Theory and Matrix Approach

  • Tinh Nguyen ,
    Kiem Nguyentien ,
    Tuan Do ,
    Tuan Pham :

    Abstract: This article represents a neural network-based adaptive sliding mode control (ASMC) method for tracking of a nonholonomic wheeled mobile robot (WMR) subject to unknown wheel slips, model uncertainties and unknown bounded disturbances. Self-recurrent wavelet neural networks (SRWNN) are employed in order to approximate unknown nonlinear functions due to the unknown wheel slips, model uncertainties, and unknown bounded external disturbances. By doing this, their harmful effects are compensated effectively. Thanks to this control method, a desired tracking performance of the closed-loop control system is achieved where the position tracking errors converge to an arbitrarily small neighborhood of the origin, regardless their initial values. According to Lyapunov theory and LaSalle extension, the stability of the whole closed-loop system is guaranteed to achieve the desired tracking performance. It is unnecessary to preliminarily offline train the neural network weights since they are easily initiated. Online tuning algorithms are established and used, for training the weights. Computer simulations are implemented to demonstrate the validity and efficiency of this proposed control method.

    Keywords: Adaptive sliding mode control (ASMC); desired tracking performance; online tuning algorithm; unknown wheel slip; wheeled mobile robot (WMR)

  • Abbas Talimian ,
    Péter Béda :
    Dynamic Stability of a Thin Plate Subjected to Bi-Axial Edged Loads125-139en [612.73 kB - PDF]EPA-02461-00079-0070

    Abstract: The first dynamic stability of a thin rectangular plate made from linear elastic material and subjected to a bi-axial time dependent load is discussed in this study. The plate carries a combination of loads that are changing linearly with respect to the length of its edges. It is also supposed that its boundary conditions on the edges are simply supported. Relevant inertia, elastic stiffness, and stability matrices are derived by applying Finite Difference Method from a differential motion equation of the plate. Subsequently, Mathieu-Hill equation form is obtained for the plate and the first dynamic stability boundaries of the plate are elaborated for using specified load parameters.

    Keywords: rectangular plate; Finite Difference Method (FDM); bi-axial load; Dynamic stability; Mathieu-Hill equations

  • Thiyagarajan Venkatraman ,
    Somasundaram Periasamy :

    Abstract: This paper proposes a new inverter topology with minimum switches, which generates a larger numbers of output voltage levels. The major advantages of the presented topology are minimum number of power switches, minimum cost, reduction in installation area and less switching losses. Different algorithms for determination of the magnitude of voltage sources are presented. Digital based switching scheme has been proposed for low switching frequency operation. Comparative analysis of the proposed inverter topology with earlier presented topologies shows that the performance of the proposed topology is improved as compared with conventional and other recently developed topology. The performance of the presented inverter has been analyzed by simulation, using MATLAB and also the feasibility of the topology has been validated experimentally.

    Keywords: multilevel inverter; symmetric inverter; asymmetric inverter; total harmonic distortion

  • Yatish Bathla :
    Conceptual Models of Information Content for Product Modeling169-188en [549.67 kB - PDF]EPA-02461-00079-0090

    Abstract: Modeling of product as a system is the new era of virtual product development. Requirement, Functional, Logical, and Physical (RFLP) structure provides system engineering based product definition in product modeling which allows to more effectively translate requirements of the customers into the physical form. But, it is difficult in RFLP structure to store and organize the knowledge of product model in a generic format so that engineers of different disciplines gain detailed knowledge of participating components in order to make the most effective decision. In this paper, a conceptual model is proposed by classifying the information content. This is done in context of the engineering discipline and system behavior. Info-Chunk is proposed in the logical level of RFLP structure. They are mapped with the information content and describe the parameters of the model for representing the engineering object. The models are used to guide the engineer to a precise correlating decision.

    Keywords: RFLP structure; Product modeling procedures; Information content of product model; Engineering objects management; Life cycle management of product information; Engineering discipline; System behavior

  • Ladislav Nyulászi ,
    Rudolf Andoga ,
    Peter Butka ,
    Ladislav Főző ,
    Radovan Kovacs ,
    Tomáą Moravec :

    Abstract: Modern aircraft turbojet engines represent complex systems where it is important to focus on the issues of safety, reliability, efficiency and also the reduction of maintenance costs. Continuous progress in diagnostics brings new possibilities in the implementation of progressive methods instead of traditional based on the use of hardware redundancy. The article deals with the design of the diagnostic and backup system, which uses a voting method and analytical redundancy representing computational models using experimental identification methods (polynomial models, neural networks). Part of the system is also an expert system, which is able to distinguish between engine failure and sensor error. The proposed system for jet engines was tested in laboratory conditions on a small turbojet engine iSTC-21v with positive results.

    Keywords: backup; diagnostics; experimental identification; neural networks; turbojet engine; voting method

  • Gábor Kertész ,
    Sándor Szénási ,
    Zoltán Vámossy :

    Abstract: The matching of the visual representations of two objects is a very important task in most computer vision applications. In special cases, when all objects look alike and only small differences occur, the difficulty of the task increases. In this paper, a novel method for matching low-quality images of rear-viewed vehicles is proposed, using multi-directional image projection functions. For GPU-accelerated implementations, a data-parallel algorithm is introduced. It is concluded, that the use of multiple directions with a small fixed resolution number is the most efficient, and more precise than similar techniques with smaller projection dimensions.

    Keywords: Computer Vision; Image Projections; Radon Transform; Object Matching; Vehicle Matching

  • Ernő Horváth ,
    Claudiu Pozna ,
    Radu-Emil Precup :

    Abstract: Coverage path planning for mobile robots aims to compute the shortest path that ensures the overlap of a given area, with applications in various domains. This paper proposes a coverage path planning strategy, referred to as Iterative Structured Orientation Coverage, which has two main advantages over the state-of-the-art, namely it is it versatile and it is capable to handle complex environments. The path planning strategy is expressed as three new approaches to coverage path planning. The suggested approaches are validated by simulation and experimental results. The source codes along with the test set are available in a public repository.

    Keywords: Auxiliary lines; Coverage path planning; Iterative Structure Orientation Coverage; Main lines; Mobile