Zoltán Nagy

Dr. Zoltán Nagy

orcid

Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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28 May 2020 in IEEE Transactions on Biomedical Engineering
Verified
Journal Article
Open access
LSLaszlo Schaffer
Laszlo Schaffer
ZNZoltán Nagy
Zoltán Nagy
ZKZoltan Kincses
Zoltan Kincses
RFRichárd Fiáth
Richárd Fiáth
UIUlbert István
Ulbert István
Spiking activity of individual neurons can be separated from the acquired multi-unit activity with spike sorting methods. Processing the recorded high-dimensional neural data can take a large amount of time when performed on general-purpose computers. Methods: In this paper, an FPGA- based real-time spike sorting system is presented which takes into account the spatial correlation between the electrical signals recorded with closely-packed recording sites to cluster multi- channel neural data. The system uses a spatial window-based version of the Online Sorting algorithm, which uses unsupervised template-matching for clustering. Results: The test results show that the proposed system can reach an average of 86% using simulated data (16-32 neurons, 4-10 dB Signal-to-Noise Ratio), while the single-channel clustering version achieves only 74% average accuracy in the same cases on a 128-channel electrode array. The developed system was also tested on in vivo cortical recordings obtained from an anesthetized rat. Conclusion: The proposed FPGA-based spike sorting system can process more than 11000 spikes/second, so it can be used during in vivo experiments providing real-time feedback on the location and electrophysiological properties of well-separable single units. Significance: The proposed spike sorting system could be used to reduce the positioning error of the closely-packed recording site during a neural measurement.

14 October 2019 in Physical Review D
Verified
Journal Article
Open access
PDF file
ZNZoltán Nagy
Zoltán Nagy
DSDavison E. Soper
Davison E. Soper
We study the probability for no jets with transverse momenta above a given cut to be found in the rapidity region between two high PT jets with a large rapidity separation. Our investigation uses the parton shower event generator deductor with color beyond the leading-color-plus approximation included perturbatively.

1 August 2012
Verified
Conference Paper
Closed access
ZNZoltán Nagy
Zoltán Nagy
CNCsaba Nemes
Csaba Nemes
Antal HibaAntal Hiba
Antal Hiba
AKAndras Kiss
Andras Kiss
ACArpad Csik
Arpad Csik
PSPeter Szolgay
Peter Szolgay
Numerical simulation of complex computational fluid dynamics problems evolving in time plays an important role in scientific and engineering applications. Accurate behavior of dynamical systems can be understood using large scale simulations which traditionally requires expensive super-computing facilities. In the paper a Field Programmable Gate Array (FPGA) based framework is described to accelerate simulation of complex physical spatio-temporal phenomena. Simulating complicated geometries requires unstructured spatial discretization which results in irregular memory access patterns severely limiting computing performance. Data locality is improved by mesh node renumbering technique which results in a sequential memory access pattern. Additionally storing a small window of cell-centered state values in the on-chip memory of the FPGA can increase data reuse and decrease memory bandwidth requirements. Generation of the floating-point data path and control structure of the arithmetic unit containing dozens of operators is a very challenging task when the goal is high operating frequency. Efficiency and use of the framework is described by a case study solving the Euler equations on an unstructured mesh using finite volume technique. On the currently available largest FPGA the generated architecture contains three processing elements working in parallel providing 75 times speedup compared to a high performance microprocessor.

2 May 2021 in International Journal of Circuit Theory and Applications
Verified
Journal Article
Open access
PDF file
AFAttila Fejér
Attila Fejér
ZNZoltán Nagy
Zoltán Nagy
JBJenny Benois‐Pineau
Jenny Benois‐Pineau
PSPéter Szolgay
Péter Szolgay
ARAymar de Rugy
Aymar de Rugy
JDJean‐Philippe Domenger
Jean‐Philippe Domenger
Summary: In this paper we describe an FPGA implementation of the Scale Invariant Feature Transform (SIFT) algorithm. The FPGA is required as its a lightweight device which makes it ideal for vision‐guided hybrid neuro‐prostheses utilised for upper limbs replacement. SIFT point detection is needed for computation of coordinates of the object‐to‐grasp in a wearable multi‐camera system. A modified SIFT algorithm is proposed and an implementation of it into C/C++ language on Xilinx ZCU102 FPGA board. The proposed hybrid hardware/software solution is compared to other hardware or hybrid implementations of the SIFT algorithm and with the baseline software detector OpenSIFT. The algorithm optimised for FPGA gives an average precision of 0.84 and the average recall of 0.94 in SIFT‐point detection compared to the baseline.The proposed solution has lower dissipated power than other solutions like CPU or GPU, and it has better computational speed.This solution allows for processing medium‐sized images in real‐time with low power consumption.

12 February 2022 in Journal of Imaging
Verified
Journal Article
Open access
PDF file
AFAttila Fejér
Attila Fejér
ZNZoltán Nagy
Zoltán Nagy
JBJenny Benois-Pineau
Jenny Benois-Pineau
PSPéter Szolgay
Péter Szolgay
ARAymar de Rugy
Aymar de Rugy
JDJean-Philippe Domenger
Jean-Philippe Domenger
The present paper proposes an implementation of a hybrid hardware–software system for the visual servoing of prosthetic arms. We focus on the most critical vision analysis part of the system. The prosthetic system comprises a glass-worn eye tracker and a video camera, and the task is to recognize the object to grasp. The lightweight architecture for gaze-driven object recognition has to be implemented as a wearable device with low power consumption (less than 5.6 W). The algorithmic chain comprises gaze fixations estimation and filtering, generation of candidates, and recognition, with two backbone convolutional neural networks (CNN). The time-consuming parts of the system, such as SIFT (Scale Invariant Feature Transform) detector and the backbone CNN feature extractor, are implemented in FPGA, and a new reduction layer is introduced in the object-recognition CNN to reduce the computational burden. The proposed implementation is compatible with the real-time control of the prosthetic arm.

1 October 2018 in Journal of Structural Biology
Verified
Journal Article
Open access
AKAkos Kovacs
Akos Kovacs
DDDániel Dudola
Dániel Dudola
LNLászló Nyitray
László Nyitray
GTGábor Tóth
Gábor Tóth
ZNZoltán Nagy
Zoltán Nagy
ZGZoltán Gáspári
Zoltán Gáspári
Single alpha-helices (SAHs) are increasingly recognized as important structural and functional elements of proteins. Comprehensive identification of SAH segments in large protein datasets was largely hindered by the slow speed of the most restrictive prediction tool for their identification, FT_CHARGE on common hardware. We have previously implemented an FPGA-based version of this tool allowing fast analysis of a large number of sequences. Using this implementation, we have set up of a semi-automated pipeline capable of analyzing full UniProt releases in reasonable time and compiling monthly updates of a comprehensive database of SAH segments. Releases of this database, denoted CSAHDB, is available on the CSAHserver 2 website at csahserver.itk.ppke.hu. An overview of human SAH-containing sequences combined with a literature survey suggests specific roles of SAH segments in proteins involved in RNA-based regulation processes as well as cytoskeletal proteins, a number of which is also linked to the development and function of synapses.