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Dr. Marius Păun
Transilvania University of Brasov, Brasov, Romania

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Research Keywords & Expertise

0 Vibrations
0 Fractal interpolation
0 Finsler geometry
0 applied algorithms
0 Invariant Lagrange Geometry

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Journal article
Published: 10 July 2021 in Symmetry
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In this, paper, we propose a method of kinematic analysis of a planar mechanism with application to the flap and wing mechanism of a light sport aircraft. A topological model is used to describe a mechanical system, which is a model that allows the study of the maneuverability of the system. The proposed algorithm is applied to determine the velocity and acceleration field of this multibody mechanical system. The graph associated with the mechanical system is generated in a new formulation and based on it, the fundamental loops of the graph are identified (corresponding to the independent loops of the mechanism), the equations for closing vectorial contours are written, and the kinematic conditions for determining velocities and accelerations and the associated linear systems are solved, which provides the field of speeds and accelerations. Graph Theory is applied at a kinematic level and not at a dynamic level, as in previous studies. A practical application for the kinematic analysis of the control mechanism of a light aircraft illustrates the proposed method.

ACS Style

Sorin Vlase; Ion-Marius Ghiţescu; Marius Paun. A Kinematical Analysis of the Flap and Wing Mechanism of a Light Sport Aircraft Using Topological Models. Symmetry 2021, 13, 1243 .

AMA Style

Sorin Vlase, Ion-Marius Ghiţescu, Marius Paun. A Kinematical Analysis of the Flap and Wing Mechanism of a Light Sport Aircraft Using Topological Models. Symmetry. 2021; 13 (7):1243.

Chicago/Turabian Style

Sorin Vlase; Ion-Marius Ghiţescu; Marius Paun. 2021. "A Kinematical Analysis of the Flap and Wing Mechanism of a Light Sport Aircraft Using Topological Models." Symmetry 13, no. 7: 1243.

Journal article
Published: 01 April 2021 in Mathematics
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The present paper concretizes the models proposed by S. Ri and N. Secelean. S. Ri proposed the construction of the fractal interpolation function (FIF) considering finite systems consisting of Rakotch contractions, but produced no concretization of the model. N. Secelean considered countable systems of Banach contractions to produce the fractal interpolation function. Based on the abovementioned results, in this paper, we propose two different algorithms to produce the fractal interpolation functions both in the affine and non-affine cases. The theoretical context we were working in suppose a countable set of starting points and a countable system of Rakotch contractions. Due to the computational restrictions, the algorithms constructed in the applications have the weakness that they use a finite set of starting points and a finite system of Rakotch contractions. In this respect, the attractor obtained is a two-step approximation. The large number of points used in the computations and the graphical results lead us to the conclusion that the attractor obtained is a good approximation of the fractal interpolation function in both cases, affine and non-affine FIFs. In this way, we also provide a concretization of the scheme presented by C.M. Păcurar.

ACS Style

Alexandra Băicoianu; Cristina Păcurar; Marius Păun. A Concretization of an Approximation Method for Non-Affine Fractal Interpolation Functions. Mathematics 2021, 9, 767 .

AMA Style

Alexandra Băicoianu, Cristina Păcurar, Marius Păun. A Concretization of an Approximation Method for Non-Affine Fractal Interpolation Functions. Mathematics. 2021; 9 (7):767.

Chicago/Turabian Style

Alexandra Băicoianu; Cristina Păcurar; Marius Păun. 2021. "A Concretization of an Approximation Method for Non-Affine Fractal Interpolation Functions." Mathematics 9, no. 7: 767.

Journal article
Published: 15 December 2020 in Forests
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Sawmilling operations are typically one of the most important cells of the wood supply chain as they take the log assortments as inputs to which they add value by processing lumber and other semi-finite products. For this kind of operations, and especially for those developed at a small scale, long-term monitoring data is a prerequisite to make decisions, to increase the operational efficiency and to enable the precision of operations. In many cases, however, collection and handling of such data is limited to a set of options which may come at high costs. In this study, a low-cost solution integrating offline object tracking, signal processing and artificial intelligence was tested to evaluate its capability to correctly classify in the time domain the events specific to the monitoring of wood sawmilling operations. Discrete scalar signals produced from media files by tracking functionalities of the Kinovea® software (13,000 frames) were used to derive a differential signal, then a filtering-to-the-root procedure was applied to them. Both, the raw and filtered signals were used as inputs in the training of an artificial neural network at two levels of operational detail: fully and essentially documented data. While the addition of the derived signal made sense because it improved the outcomes of classification (recall of 92–97%) filtered signals were found to add less contribution to the classification accuracy. The use of essentially documented data has improved substantially the classification outcomes and it could be an excellent solution in monitoring applications requiring a basic level of detail. The tested system could represent a good and cheap solution to monitor sawmilling facilities aiming to develop our understanding on their technical efficiency.

ACS Style

Stelian Alexandru Borz; Marius Păun. Integrating Offline Object Tracking, Signal Processing, and Artificial Intelligence to Classify Relevant Events in Sawmilling Operations. Forests 2020, 11, 1333 .

AMA Style

Stelian Alexandru Borz, Marius Păun. Integrating Offline Object Tracking, Signal Processing, and Artificial Intelligence to Classify Relevant Events in Sawmilling Operations. Forests. 2020; 11 (12):1333.

Chicago/Turabian Style

Stelian Alexandru Borz; Marius Păun. 2020. "Integrating Offline Object Tracking, Signal Processing, and Artificial Intelligence to Classify Relevant Events in Sawmilling Operations." Forests 11, no. 12: 1333.

Journal article
Published: 15 October 2019 in Symmetry
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The paper focuses on the vibration analysis of a vehicle equipped with two identical engines. Such solutions are encountered in practice when less power is needed for a vehicle for a certain period of time and then greater power the rest of the time. An example of this would be a mobile drilling rig. During transport (a relatively short period of time) only one engine operates and then, in service (most of the operating time), both engines operate. A characteristic of such an aggregate is the existence, within the transmission, of two identical engines. The existence of identical parts in mechanical systems leads to properties that allow the computations to be simplified in order to obtain suggestive and rapid results, with reduced computation effort. These properties refer to the eigenvalues and eigenmodes of vibration for these types of systems and have been stated and demonstrated in the paper. It also allows for a qualitative analysis of the behavior of the system in case of vibrations. The existence of these properties allows for easier calculation and shortening of the design time. The mechanical consequences of the existence of symmetries or identical parts have begun to be studied in more detail in the last decade (see references), and the work is part of these trends. The vibration properties of a transmission of a truck with two identical engines have been stated and proven and a real example is analyzed. Two 215 hp engines were used in the application. In order to establish a useful solution in practice, two constructive variants with a different clutch position in the transmission are analyzed in parallel.

ACS Style

Mircea Mihălcică; Sorin Vlase; Marius Păun. The Use of Structural Symmetries of a U12 Engine in the Vibration Analysis of a Transmission. Symmetry 2019, 11, 1296 .

AMA Style

Mircea Mihălcică, Sorin Vlase, Marius Păun. The Use of Structural Symmetries of a U12 Engine in the Vibration Analysis of a Transmission. Symmetry. 2019; 11 (10):1296.

Chicago/Turabian Style

Mircea Mihălcică; Sorin Vlase; Marius Păun. 2019. "The Use of Structural Symmetries of a U12 Engine in the Vibration Analysis of a Transmission." Symmetry 11, no. 10: 1296.