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Found 6289 publications

Formation control of quadrotor helicopters with guaranteed collision avoidance via safe path

Gergely Regula Bela Lantos

Publication Name: Periodica Polytechnica Electrical Engineering and Computer Science

Publication Date: 2012-01-01

Volume: 56

Issue: 4

Page Range: 113-124

Description:

In this article we propose a hierarchical control structure for multi-agent systems. The main objective is to perform formation change manoeuvres, with guaranteed safe distance between each two vehicles throughout the whole mission. The key components that ensure safety are a robust control algorithm that is capable of stabilising the group of vehicles in a desired formation and a higher level path generation method that provides safe paths for all the vehicles, based on graph theoretic considerations. The method can effciently handle a large group of any type of vehicles. In the article we focus on the control of quadrotor UAVs, thus the results are illustrated in 4D on a group of such vehicles.

Open Access: Yes

DOI: 10.3311/PPee.7080

Numerical methods for digitally synthetic holograms

Lotfi Abdelhakim

Publication Name: Civil Comp Proceedings

Publication Date: 2012-01-01

Volume: 100

Issue: Unknown

Page Range: Unknown

Description:

The main purpose of this paper is to develop a program package which generates artificial holograms by numerical methods and these computer generated holograms are numerically reconstructed. For the calculation of light propagation needed in the generation of holograms or in the reconstruction of the object from the hologram, two strategies are used. The first is the Fourier-based algorithm where the diffraction integral is approximated as a convolution integral, allowing computation using the fast Fourier transform algorithm. The second uses finite difference discretization to solve the parabolic wave equation. Numerical tests that assess the accuracy of these algorithms are presented. © Civil-Comp Press, 2012.

Open Access: Yes

DOI: DOI not available

Hierarchical-interpolative fuzzy system construction by genetic and bacterial memetic programming approaches

Krisztián Balázs László T. Kóczy

Publication Name: International Journal of Uncertainty Fuzziness and Knowldege Based Systems

Publication Date: 2012-01-01

Volume: 20

Issue: SUPPL. 2

Page Range: 105-131

Description:

In this paper a family of new methods are proposed for constructing hierarchical-interpolative fuzzy rule bases in the frame of a fuzzy rule based supervised machine learning system modeling black box systems defined by input-output pairs. The resulting hierarchical rule base is constructed by using structure building pure evolutionary and memetic techniques, namely, Genetic and Bacterial Programming Algorithms and their memetic variants containing local search steps. Applying hierarchical-interpolative fuzzy rule bases is a rather efficient way of reducing the complexity of knowledge bases, whereas evolutionary methods (including memetic techniques) ensure a relatively fast convergence in the learning process. As it is presented in the paper, by applying a newly proposed representation schema these approaches can be combined to form hierarchical-interpolative machine learning systems. © 2012 World Scientific Publishing Company.

Open Access: Yes

DOI: 10.1142/S021848851240017X

Solution of the convex programming problem via second order differential equation system

Tamás Hajba M. Kovács

Publication Name: Miskolc Mathematical Notes

Publication Date: 2012-01-01

Volume: 13

Issue: 1

Page Range: 23-37

Description:

In this paper we investigate a family of second order differential equations which can be considered as the continuous versions of the Fletcher-Reeves iteration for minimization applied to a regularized and penalized convex programming problem. We show that synchronizing the parameter functions of the differential equation the stationary limit point of the trajectories is the minimal norm solution of the given convex programming problem. © 2012 Miskolc University Press.

Open Access: Yes

DOI: 10.18514/mmn.2012.327

Modelling of an electroactive polymer actuator

Ákos Aczél

Publication Name: Procedia Engineering

Publication Date: 2012-01-01

Volume: 48

Issue: Unknown

Page Range: 1-9

Description:

The aim of this paper is to build a model of an electroactive polymer actuator when external electric field is applied. Materials whose rheological properties can be varied by electric excitation are called electroactive materials. The behavior of these rubberlike media is commonly investigated in two different ways. Brigadnov, Dorfmann, Bustamante, Ogden and others describe the coupled problem of finite deformation of the continua in electromagnetic field by taking into account all the electromagnetic phenomena. Pelrine, Kornbluh, Sommer-Larsen and others present a phenomenological description. Our aim is to form a bridge between these two points of view by neglecting those terms of the governing and transformation equations that are smaller than other contributions by several orders of magnitude. First, those equations are presented that govern the finite deformation and the electromagnetic phenomena inside the material. After that, those estimations will be taken that show the order of magnitude of the different contributions to the so-called effective fields. Finally, the model of the EAP actuator under periodically changing electric field will be presented. Because of the periodically changing finite deformation of the actuator, the electromagnetic phenomena must be investigated in the rest frames fixed to every single point of the material body. The electromagnetic field-variables can be converted into the laboratory frame by the slow speed approximation of the Lorentz transformation. For the special case of thin electroactive polymer actuators, one can find that the velocity dependent contributions are smaller by ten orders of magnitude in the electric field transformation, and by five orders of magnitude in the magnetic field transformation equations. On the other hand, none of the terms of the effective current can be neglected, because they can be of the same order of magnitude as the free current. © 2012 Published by Elsevier Ltd.

Open Access: Yes

DOI: 10.1016/j.proeng.2012.09.477

Development of production logistics system based on lean principles

No authors available

Publication Name: International Conference on Industrial Logistics, ICIL 2012 - Conference Proceedings

Publication Date: 2012-01-01

Volume:

Issue:

Page Range: 349-355

Description:

This paper acquaints the production logistics system about a Hungarian operating vehicle part manufacturing company, including its examination, and development opportunities. This paper's highlighted objectives are the preparation and analysis of the basic data of development recommendation. Moreover, it demonstrates lean based outsourcing strategies which could significantly reduce the company's handling demands.

Open Access: No

DOI: DOI not available

Trade-offs in production supply systems

Csaba Tápler Janos Kovacs

Publication Name: International Conference on Industrial Logistics Icil 2012 Conference Proceedings

Publication Date: 2012-01-01

Volume: Unknown

Issue: Unknown

Page Range: 356-361

Description:

The cost price of a final product depends on - among others - the cost of value added processes such as production supply. When planning the supply strategy and defining the parameters of the processes we face a lot of trade-off situations (e.g.: decision between kanban or other supply strategy, kanban quantity, production line loading cycle time, maximal number of picking items on picking lists, etc.). The aim of this paper is to list these decision situations and give adequate solutions on them. By means of mathematical modeling we define the optimal system parameter configuration of a production supply system where the total cost is minimal.

Open Access: Yes

DOI: DOI not available

Trade-offs in production supply systems

No authors available

Publication Name: International Conference on Industrial Logistics, ICIL 2012 - Conference Proceedings

Publication Date: 2012-01-01

Volume:

Issue:

Page Range: 356-361

Description:

The cost price of a final product depends on - among others - the cost of value added processes such as production supply. When planning the supply strategy and defining the parameters of the processes we face a lot of trade-off situations (e.g.: decision between kanban or other supply strategy, kanban quantity, production line loading cycle time, maximal number of picking items on picking lists, etc.). The aim of this paper is to list these decision situations and give adequate solutions on them. By means of mathematical modeling we define the optimal system parameter configuration of a production supply system where the total cost is minimal.

Open Access: No

DOI: DOI not available

Application of design tools in carbody construction harmonizing shape and dynamical load

No authors available

Publication Name: Proceedings of the Mini Conference on Vehicle System Dynamics, Identification and Anomalies

Publication Date: 2012-01-01

Volume: 2012-November

Issue:

Page Range: 379-386

Description:

There are two main areas highlighted in the paper concerning car body manufacturing: construction and design work or in other words functionality and aesthetics. The question is to be answered: Which is more important? The solution is untying this quasi contradiction, but it is not an easy task. The ergonomical and aesthetical demands are not unambiguous; they depend also on weather conditions, different anthropometrics, changeable conditions during operation, attitudes, traditions, mentalities, local and actual trends etc. Nowadays the external and internal design does not belong to the main constructor or automotive engineer. The major original equipment manufacturers (OEM) charge special designers to do such work similarly to the separated engine, axles, brake system, electric network design. Nevertheless there are many details that must fit together in the vehicle. As long as the different engineering interests can be harmonized in a rational way, in aesthetical and design questions tastes can be decisive beside rationality. This makes the decisions difficult. The GIST of the cooperation is that future automotive engineers must know the designer's way of thinking at least the main stream in order to consider and make good decisions.

Open Access: No

DOI: DOI not available