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Found 6289 publications

Development of a VR capable virtual laboratory framework

Miklós Kuczmann Tamás Budai

Publication Name: Pollack Periodica

Publication Date: 2018-12-01

Volume: 13

Issue: 3

Page Range: 83-93

Description:

The aim of this paper is to introduce the design steps and implementation details of a system, which combines modern web-technologies and open-source simulation software to create a virtual laboratory framework. In order to validate the functionality of this framework and to demonstrate its capabilities, a classic experiment from the field of control theory was implemented; the inverted pendulum. In this experiment, a simulated controller keeps the rod of the pendulum in an upright position. Users can change different parameters of the model and then test the impact of these changes in a very intuitive and interactive way, by applying force to the pendulum model in 3D and observing the behavior of the controller.

Open Access: Yes

DOI: 10.1556/606.2018.13.3.9

Numerical examination of nonlinear oscillators

F. Hajdu

Publication Name: Pollack Periodica

Publication Date: 2018-12-01

Volume: 13

Issue: 3

Page Range: 95-106

Description:

The numerical examination of nonlinear oscillators is presented in this paper. First some methods of nonlinear system modeling are described then the numerical creation of phase-plane, bifurcation diagrams and Poincaré sections are expounded in detail. The next part of the paper is the numerical examination of nonlinear oscillators, like the Duffing-Holmes oscillator and a mechatronic semi-active suspension system. The paper concludes with further development tasks.

Open Access: Yes

DOI: 10.1556/606.2018.13.3.10

Comparative study of the application of steels and aluminium in lightweight production of automotive parts

Imre Czinege Miklos Tisza

Publication Name: International Journal of Lightweight Materials and Manufacture

Publication Date: 2018-12-01

Volume: 1

Issue: 4

Page Range: 229-238

Description:

The automotive industry has a decisive role in the economy of developed countries. Sheet metal forming – as one of the main processes in car manufacturing – has similarly important role. Concerning the recent trends in car production, the application of lightweight constructions principles is the main priority to meet customers' demands and the increased legal requirements. To meet these expectations, the application of high strength materials is regarded as one of the most promising possibilities. Applying high strength materials – beside high strength steels like DP1000, TRIP780 recently aluminium alloys, e.g. AA7021 or AA7075 – have a positive response for many of the requirements: increasing strength results in the application of thinner sheets together with significant mass reduction, leading to lower consumption with increased environment protection; however it can often lead to the decrease of formability, too. In this paper, an introduction on recent material developments in the automotive industry concerning both the use of new generation high strength steels and light metals with particular emphasis on aluminium alloys will be given. A comparison between steel and aluminium application in the automotive industry is given from various points of view. Since our main topic is the sheet metal forming, in this paper the body-in-white manufacturing in the automotive industry is the primary focus field.

Open Access: Yes

DOI: 10.1016/j.ijlmm.2018.09.001

Computation of sensitivity of periodically excited dynamical systems

Mate Antali Zoltán Horváth

Publication Name: Journal of Engineering Mathematics

Publication Date: 2018-12-01

Volume: 113

Issue: 1

Page Range: 123-142

Description:

In the optimization of continuous-time dynamical systems, it can be important to numerically calculate the parametric sensitivity of some long-time-averaged quantities in the system. These computations are challenging for typical numerical methods in the presence of oscillations, which can originate from the internal structure of an autonomous dynamical system or be caused by an external periodic excitation. The case of periodic excitation is motivated by the problem of heat conduction in mechanical parts in engines, where the mean strength of the heat fluctuation can be an important parameter in the engineering design. In this work, approaches to transform periodically excited systems into autonomous systems appropriate for sensitivity analysis were investigated. The least-squares shadowing method is used to compute the sensitivities, and the effect of different kinds of transformation compared. The resulting numerical method is presented using the motivating example of heat conduction.

Open Access: Yes

DOI: 10.1007/s10665-018-9977-3

Using numerical modeling error analysis methods to indicate changes in a watershed

Katalin Bene Kevin Mátyás

Publication Name: Pollack Periodica

Publication Date: 2018-12-01

Volume: 13

Issue: 3

Page Range: 175-186

Description:

In order to promote long-term sustainable water management in northwestern Hungary, decision-makers need to understand the hydrological variability in the region. To better quantify hydrological variability in the region, this study developed rainfall-runoff models of four watersheds in the Little Hungarian Plain. The models were then used to identify variations in runoff characteristics caused by climatic factors or fundamental alterations to the watershed itself through the application of numerical error analysis. By observing the continuous statistical error measurements, changes can be detected in either climatic conditions, watershed characteristics, or may indicate gauging or data collection errors.

Open Access: Yes

DOI: 10.1556/606.2018.13.3.17

Invariance Preserving Discretization Methods of Dynamical Systems

Yunfei Song Tamás Terlaky Zoltán Horváth

Publication Name: Vietnam Journal of Mathematics

Publication Date: 2018-12-01

Volume: 46

Issue: 4

Page Range: 803-823

Description:

In this paper, we consider local and uniform invariance preserving steplength thresholds on a set when a discretization method is applied to a linear or nonlinear dynamical system. For the forward or backward Euler method, the existence of local and uniform invariance preserving steplength thresholds is proven when the invariant sets are polyhedra, ellipsoids, or Lorenz cones. Further, we also quantify the steplength thresholds of the backward Euler methods on these sets for linear dynamical systems. Finally, we present our main results on the existence of uniform invariance preserving steplength threshold of general discretization methods on general convex sets, compact sets, and proper cones both for linear and nonlinear dynamical systems.

Open Access: Yes

DOI: 10.1007/s10013-018-0305-z

Conformal cooling with heat-conducting inserts by direct metal laser sintering

István Hatos B. Kocsis H. Hargitai

Publication Name: Iop Conference Series Materials Science and Engineering

Publication Date: 2018-11-30

Volume: 448

Issue: 1

Page Range: Unknown

Description:

With the development of layer manufacturing technologies injection mold inserts with conformal cooling channels can be manufactured. If the cooling channels can be placed along the geometry, the heat removal is uniform and effective. In tight mold regions, formation of cooling channel is not possible or not efficient. The combination of conformal cooling and heat conductive insert can be an ideal solution for the effective cooling.

Open Access: Yes

DOI: 10.1088/1757-899X/448/1/012027

A switched linear system approach to the modeling of the air path of diesel engines

Zsolt Horváth Petra Csomós

Publication Name: Aip Conference Proceedings

Publication Date: 2018-11-30

Volume: 2040

Issue: Unknown

Page Range: Unknown

Description:

This paper discusses the designing of switched linear system to the modeling of the air path of diesel engines for purpose of fault detection. The main goal for further investigation is to extend our proposed H-infinity robust filtering procedure for the entire engine operational range. For this reason, an appropriate modelling approach are needed to handle the nonlinear engine model. Our idea is to design a switched system being reasonable for approximation of the main attribute of the nonlinear system, moreover, it can be handled as a linear system. This is done by creating linear time-invariant systems for various operating points of a nonlinear plant and, based on a pre-defined switching rule, we switch between them. After a short introduction of mathematical results how to derive a switched system, we explain the steps of the designed procedure. Finally, the applicability is demonstrated based on the model of air path of diesel engines via MATLAB simulations.

Open Access: Yes

DOI: 10.1063/1.5079206

Measuring and the hysteresis characteristics of permanent magnet

Miklós Kuczmann Gergely Kovács

Publication Name: Physica B Condensed Matter

Publication Date: 2018-11-15

Volume: 549

Issue: Unknown

Page Range: 62-68

Description:

Knowledge of the hysteresis characteristics of permanent magnets is one of the focal point of electric motor design. Permanent magnets are widely used in PMSM (Permanent Magnet Synchronous Motor) and BLDC (Brushless DC) motors that can be found in electric vehicles. The paper deals with the implementation of a permanent magnet measurement set-up as well as the finite element simulation of the developed arrangement. The purpose of this work is to realize an accurate model of permanent magnet obtained by measurement parameters.

Open Access: Yes

DOI: 10.1016/j.physb.2017.09.090