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Found 6289 publications

Li-BES detection system for plasma turbulence measurements on the COMPASS tokamak

M. Berta G. Anda D. Dunai P. Hacek D. Réfy A. Kovácsik J. Krbec M. Hron G. Veres R. Pánek S. Zoletnik A. Bencze V. Weinzettl

Publication Name: Fusion Engineering and Design

Publication Date: 2015-10-01

Volume: 96-97

Issue: Unknown

Page Range: 795-798

Description:

A new Li beam emission spectroscopy (Li-BES) diagnostic system with a ∼ cm spatial resolution, and with beam energy ranging from 10 keV up to 120 keV and a 18 channel Avalanche photo diode (APD) detector system sampled at 2 MHz has been recently installed and tested on the COMPASS tokamak. This diagnostic allows to reconstruct density profile based on directly measured light profiles, and to follow turbulent behaviour of the edge plasma. The paper reports technical capabilities of this new system designed for fine spatio-temporal measurements of plasma electron density. Focusing on turbulence-induced fluctuation measurements, we demonstrate how physically relevant information can be extracted using the COMPASS Li-BES system.

Open Access: Yes

DOI: 10.1016/j.fusengdes.2015.06.030

On Preservation of Positivity in Some Finite Element Methods for the Heat Equation

Panagiotis Chatzipantelidis Vidar Thomée Zoltán Horváth

Publication Name: Computational Methods in Applied Mathematics

Publication Date: 2015-10-01

Volume: 15

Issue: 4

Page Range: 417-437

Description:

We consider the initial boundary value problem for the homogeneous heat equation, with homogeneous Dirichlet boundary conditions. By the maximum principle the solution is nonnegative for positive time if the initial data are nonnegative. We complement in a number of ways earlier studies of the possible extension of this fact to spatially semidiscrete and fully discrete piecewise linear finite element discretizations, based on the standard Galerkin method, the lumped mass method, and the finite volume element method. We also provide numerical examples that illustrate our findings.

Open Access: Yes

DOI: 10.1515/cmam-2015-0018

Evolving spiking neural network for robot locomotion generation

János Botzheim Noriko Takase Naoyuki Kubota

Publication Name: 2015 IEEE Congress on Evolutionary Computation CEC 2015 Proceedings

Publication Date: 2015-09-10

Volume: Unknown

Issue: Unknown

Page Range: 558-565

Description:

In this paper, we propose locomotion generation for a mobile robot. Legged robot can walk in various complex terrains such as stairs as well as in flat environment. However, setting its behaviour to adapt to various environments in advance is very difficult. The robot can mimic the movement of organisms based on computational intelligence. In this study, we apply spiking neural network, which can take into account the transition of temporal information between the neurons. More specifically, the motion patterns are generated by applying a spiking neural network trained by Hebbian learning and evolution strategy, by using data provided by the physics engine measuring the distance walked by the robot and applied the motion patterns to real robot. Simulation was conducted to confirm the proposed technique.

Open Access: Yes

DOI: 10.1109/CEC.2015.7256939

Evaluation of waste management systems using fuzzy cognitive maps and optimization

Miklós F. Hatwágner Peter Foldesi Adrienn Buruzs L. T. Kóczy

Publication Name: 2015 10th Asian Control Conference Emerging Control Techniques for A Sustainable World Ascc 2015

Publication Date: 2015-09-08

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Integrated Waste Management Systems (IWMS) are very complex systems with a lot of uncertainty. These can be defined as the selection and application of suitable techniques, technologies and management programs to achieve waste management objectives and goals. In order to support the decision making process in waste management we propose the use of Fuzzy Cognitive Map (FCM) and Bacterial Evolutionary Algorithm (BEA) methods since the combination of the FCM and BEA seem to be suitable to model complex mechanisms such as IWMS. While the FCM is formed for a chosen system by determining the concepts and their relationships, it is possible to quantitatively simulate the system considering its parameters. However, if the time series of the factors of the system are known, then the connection matrix of FCM, thus the causal relations among the parameters can be determined by optimization. This way a more objective description of IWMS can be given.

Open Access: Yes

DOI: 10.1109/ASCC.2015.7244894

Parameter dependence of fuzzy cognitive maps' behaviour

Miklós F. Hatwágner András Torma L. T. Kóczy

Publication Name: 2015 10th Asian Control Conference Emerging Control Techniques for A Sustainable World Ascc 2015

Publication Date: 2015-09-08

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Stakeholder Relationship Management Systems (SRMS) are conventionally analyzed by a static way, which hides the interconnections of the system. Authors investigated a novel approach to make the evaluation of the interconnections of the SRMS and their behavior achievable. The Fuzzy Cognitive Maps (FCM) is a proper tool to investigate the properties of SRMS. The simulation of SRMS with FCM supports the business management process and different project support activities. If the factors of SRMS themselves, the initial states of them and causality relations among them are already determined, a simulation can be easily carried out. In some specific situations the results of the simulation is hard to use in practice, however. If the differences between factor states are very small, the order (importance) of factors cannot be defined. In such cases the modification of the threshold function's parameter can help to better separate final factor states. This paper deals with the investigation of this approach.

Open Access: Yes

DOI: 10.1109/ASCC.2015.7244823

Robust reconfigurable control for in-wheel electric vehicles

Timea Fülep Andras Mihaly Zoltán Szabó Peter Gaspar Ferenc Szauter József Bokor

Publication Name: IFAC Papersonline

Publication Date: 2015-09-01

Volume: 28

Issue: 21

Page Range: 36-41

Description:

The paper presents a fault tolerant reconfigurable control method for vehicles driven by four in-wheel electric motors and a steering system. The aim of the design is to realize robust velocity and road trajectory tracking even under challenging driving conditions or actuator failures. The vehicle is operated solely with the in-wheel motors, thus steering intervention is only applied in case of skidding or a failure of an electric motor. The reconfigurable control is realized based on Linear Parameter Varying (LPV) framework, using the specific characteristics of the in-wheel motors of fast and accurate torque control. The operation of the designed control system is demonstrated in a CarSim simulation environment.

Open Access: Yes

DOI: 10.1016/j.ifacol.2015.09.501

Investigation of 3D SPECT reconstruction with multi-energy photon emitters 1

B. Benyo Gábor Hesz K. Kovacs Ákos Szlávecz

Publication Name: IFAC Papersonline

Publication Date: 2015-09-01

Volume: 28

Issue: 20

Page Range: 30-35

Description:

Parallel projection based Single Emission Computed Tomography is a widely used nuclear imaging technique. Non-homogeneous attenuation medium and the distance dependent spacial resolution (DDSR) of the parallel imaging cause serious artefacts during image reconstruction. Both effects are dependent on the energy of gamma photons used for imaging. In this paper an efficient parallel reconstruction algorithm is introduced that is executed on the Graphics Processing Unit. The aim of the presented study was to investigate the possibilities of reconstruction techniques when multi-energy photon emitters are used. An analytical 3D projector with attenuation and detector response modelling was used to generate projection sets for Gallium-67 isotope studies. Data were reconstructed from one photopeak only using the corresponding attenuation map. The projection data sets were added together and reconstructed using average attenuation and DDSR compensation values as well as simulating every photopeak individually. The third combined reconstruction technique was using every projection set as separate measurement. In this study we showed that all three strategies result in similar image quality, however the average attenuation correction method is computationally less demanding.

Open Access: Yes

DOI: 10.1016/j.ifacol.2015.10.110

The palace of the Hungarian Academy of Sciences as national monument

Gábor Winkler

Publication Name: Epites Epiteszettudomany

Publication Date: 2015-09-01

Volume: 43

Issue: 3-4

Page Range: 169-180

Description:

The lecture presented on the conference of the Hungarian Academy of Sciences showed interesting facts about the significance of the building and about the past of its maintenance as national monument. According to many opinions the palace of the Hungarian Academy of Sciences is the second most significant public building of Hungary. The first neo-Renaissance building of Budapest was erected in the style of Historicism, which tendency has decisively defined the townscape up to this time (Fisherman's Bastion, Buda Castle). Historicism appeared in Hungary at the beginning of the 1860s following Neo-Classicism and parallel with Romantic architecture: at first with neo-Renaissance characteristics, but later the neo-Gothic, neo-Romanesque and neo-Baroque architecture emerged as well. The presentation analysed the sources of the Hungarian laws about monument preservation, the functions of the building as monument. The palace has a significant role also as historical place and artistic relic. The lecture also presented the spatial arrangement of the building, its rich fine arts collection, its defining stylistic characteristics, and the process of restoration after the damages in World War II.

Open Access: Yes

DOI: 10.1556/096.2015.43.3-4.4

Status of land use and transport modeling in Hungary

Bertalan Gaal

Publication Name: 2015 International Conference on Models and Technologies for Intelligent Transportation Systems Mt ITS 2015

Publication Date: 2015-08-25

Volume: Unknown

Issue: Unknown

Page Range: 362-366

Description:

Since the accession to the EU, Hungary came at huge sum of development resources. These resources should serve the sustainable development of the economy of the country and its people. However, joint planning between land-use planning, regional planning and transportation planning is lacking, disendowing the utilization of possible synergies. LUTI models represent a way to deal with this problem, but Hungarian research in this field is in hiatus, and governmental interest is missing. This paper aims to draw attention to this field. It is in Hungary's best interest to develop or adopt some kind of LUTI model to enhance its developmental capability.

Open Access: Yes

DOI: 10.1109/MTITS.2015.7223280