Vladimir Gazda | Technical University of Kosice (original) (raw)

Papers by Vladimir Gazda

2017 IEEE 15th International Symposium on Applied Machine Intelligence and Informatics (SAMI), 2017

A significant increase in wireless communication has been observed in the last decade. Traditiona... more A significant increase in wireless communication has been observed in the last decade. Traditional fixed spectrum allocation presents limitations to better spectrum utilization. Real-time secondary spectrum market seems to be appropriate approach to eliminating the problem of spectrum scarcity. Economic aspects of the new approach are still only partially investigated. Besides the conventional wholesale market with wholesale price paid for frequency spectrum, we introduce new system of allocation based on tax paid by operators for unused frequency spectrum. We aim to build an agent-based model of the real-time secondary spectrum market to compare two systems of spectrum allocation. We performed parameter sensitivity analysis and robustness against initial conditions. The results of the simulation show different impact on licence owner's revenue as well as operator's revenue.

Advances in Production Engineering & Management, 2020

The shortening of the production cycle and increasing impact of the technological innovations evo... more The shortening of the production cycle and increasing impact of the technological innovations evokes improvement of the methods used in the production line scheduling. The aim of the presented research is a proposal of the decision model that enables a flexible reaction to the changing production conditions. The central decisions are substituted by the decisions performed on the independent machines level. The machines utilize rather restricted information on the capacities utilization of their technological neighbours. The decisions follow the decision tables (decision chromosomes) re-coded in the course of the evolution. The Genetic algorithms standing behind the model, enable identification of the highly acceptable solutions that is proved by a set of the simulation experiments. The set of independent machines becomes self-organized, having a significant positive effect on the production line capacities utilization. The decentralization aspect makes our proposal somewhat different from other research in the field. The philosophy is built on the fact that each machine makes its production decision based on the available information, which it has at its disposal in a given time. The machine flexible reacts to its neighbours' capacity utilization (machine before and after given production machine) in the production process flow.

Sociální studia / Social Studies, 2016

Důvěra a reciprocita vstupují do většiny osobních, sociálních a ekonomických interakcí. Zatímco k... more Důvěra a reciprocita vstupují do většiny osobních, sociálních a ekonomických interakcí. Zatímco kooperativní chování se může realizovat k užitku partnerů interakce, sobeckost a nereciproční jednání mohou škodit. V článku prezentujeme investiční hru s plnou (symetrickou) informací a parciální (asymetrickou) informací. V experimentu též zavádíme očekávání subjektů ohledně chování protistrany interakce. To nám umožňuje pozorovat vedlejší motivy chování účastníků experimentu. Experiment opakujeme v pěti kolech a pozorujeme vliv symetrické a asymetrické informace na vývoj důvěry a reciprocity. Pozorujeme odklon ekonomických agentů od neohraničeně racionálního a sobeckého chování. Subjekty se odchylují od nashovských ekvilibrií. Dokumentujeme důkaz toho, že důvěra indikuje reciprocitu. Účastníci experimentu jsou averzní vůči nespravedlnosti, ale pozorujeme nepatrně oportunistické chování v experimentu s asymetrickou informací, kde subjekty využívají informační disparitu. Efekt reputace n...

Theory, Methodology, Practice, 2018

The economic crisis that broke out in the most developed part of the world in 2008 seriously affe... more The economic crisis that broke out in the most developed part of the world in 2008 seriously affected the Central-Eastern-European bank systems. This was no wonder, because these economies were closely linked to the developed countries. Firstly, the Central-Eastern-European banks were mostly owned by large Western-European banks, and the management of these subsidiaries became tougher due to the asset management problems of their mother banks. The current paper examines the deleveraging of bank systems of this area during the crisis and thereafter. A special northern-southern division can be observed among the Central-Eastern-European banking systems, where the border is unfortunately at the northern border of Hungary. During the crisis, the amount of bank outstandings was mostly determined by the economic growth, the starting state of loan-deposit ratio, as well as the uncertainty of sovereign Credit Defalut Spread. In the aftercrisis period the change in outstandings is especially dependent on the non-performing loan ratio and the change in loandeposit ratio. Hungary is an "off-line" country for all strong correlated variable pairs, so the decrease in domestic outstandings may have country-specific reasons in addition to the general theoretical variables.

ectap.ro

Lucrarea de faţă investighează relaţiile dintre exporturi şi creşterea economică în Libia. S-a co... more Lucrarea de faţă investighează relaţiile dintre exporturi şi creşterea economică în Libia. S-a construit şi estimat un model econometric pentru a releva factorii determinanţi ai ambelor elemente, pe termen scurt şi pe termen lung. Seriile cronologice folosite în estimare acoperă perioada 1980-2007. Rezultatele indică faptul că veniturile, exporturile şi preţurile relative sunt cointegrate. Cauzalitatea bidirecţională pe termen lung dintre exporturi şi creşterea veniturilor este de asemenea demonstrată. Rezultatul studiului arată că politica de promovare a exporturilor îşi aduce contribuţia la creşterea economică din Libia.

Melecký [14]) or interest rates of different maturities (Engle and Granger [6]). By modeling the ... more Melecký [14]) or interest rates of different maturities (Engle and Granger [6]). By modeling the inter-industries relations, Strauss and Wohart [26] investigated the cointegration among prices, wages and labor productivity. The similar analysis considering the cointegration between production and employment was estimated by Upender, Chandramouli and Mendali [29]. Inter-industries labor productivity and wage rates equilibriums were analyzed by Upender and Sujan [30]. In the first section, the investigated data are described. The second and third sections are devoted to the methodology, econometric analysis followed by the results discussion.

IEEE Access

The future of networking will be driven by the current emerging trends of combining the physical ... more The future of networking will be driven by the current emerging trends of combining the physical and virtual realities in cyberspace. Considering the ambient pandemic challenges, the role of virtual and augmented reality will definitely grow over time by transforming into the paradigm of the Metaverse of Things, where each person, thing or other entity will simultaneously exist within multiple synchronized realities. In this paper, we propose a novel framework for future metaverse applications composed of multiple synchronized data flows from multiple operators through multiple wearable devices and with different quality requirements. A new service quality model is proposed based on a customizable utility function for each individual data flow. The proposed approach is based on dynamic fine-grained data flow allocation and service selection using non-fungible tokens, which can be traded over the blockchain among users and operators in a decentralized mobile network environment. 11 INDEX TERMS Blockchain, metaverse, the IoT, NFT, 5G/6G. I. INTRODUCTION 12 Evolution of the Internet of Things (IoT), artificial intel-13 ligence (AI), virtual and augmented reality (VR/AR) and 14 5G technologies is currently gaining increasing interest from 15 different industrial verticals. 16 The IoT has completely changed the landscape of modern 17 information and communication systems by enabling a bridge 18 between the real and the digital world. This is achieved by 19 providing the communication interface to low-cost devices, 20 which interact with the physical objects or environment. 21 The associate editor coordinating the review of this manuscript and approving it for publication was Chen Chen. secure data aggregation [28], mixed reality content shar-231 ing [29], COVID pandemic monitoring [30], etc. 232 Apart from the aforementioned scenarios, blockchain is 233 particularly interesting for the decentralized SLA manage-234 ment in 5G/6G mobile network, which is needed for the MoT 235 applications. The key requirement of the MoT is the flexible 236 SLA policies, with dynamic pricing, continuous monitoring 237 and control of the obligations without the third-party. Such 238 framework has been proposed in [37], where authors pro-239 posed a framework to monitor SLA terms in an automatic and 240 decentralized manner using smart contracts and blockchain 241 technologies. Similar approaches that leverage blockchain 242 and smart contracts for service management have been pro-243 posed in works [35], [38], [39], [40], [41]. 244 It should be noted that the decentralized consensus mech-245 anism of blockchain has high potential to ensure a secure 246 interoperability of many sensors and actuators in the IoT 247 system [31]. Nevertheless, there is still a challenge of find-248 ing the optimal trade-off between security, throughput and 249 energy demand of the consensus algorithm. Considering that 250 most IoT devices are constrained by power and computing 251 capabilities, this problem is of paramount importance [32], 252 [33]. Considering the huge traffic expectations and latency 253 constraints in the MoT network [34], the abovementioned 254 blockchain limitations will be the key implementation con-255 cerns, which are discussed in the following sub-subsection. 256 D. BLOCKCHAIN CONSENSUS ALGORITHMS 257 Blockchain is a peer-to-peer system where all nodes commu-258 nicate directly without a centralized entity. The consensus 259 algorithm is the key procedure of any blockchain network 260 because it defines the way distributed nodes validate each 261 transaction in a secure manner [48]. A transaction itself is 262 the record that indicates the corresponding changes in the 263 distributed ledger, which must be verified by several nodes. 264 All nodes (or more than 51%) in the blockchain must update 265 the new state of the distributed ledger, which ensures the 266 security and immutability of each transaction [49]. 267 Among all available consensus algorithms, choosing the 268 optimal algorithm is not a trivial task. The consensus algo-269 rithm specifies how data are spreading among all blockchain 270 nodes, how decisions are made by each node, and how 271 the new block of verified transactions is added to the 272 blockchain [50]. For brevity, in this paper, we will not cover 273 all available consensus algorithms, considering that there are 274 already some surveys that describe them in more detail [51], 275 [52], [53], [54]. Instead, in the next subsection, we briefly 276 compare the most widely adopted consensus algorithms and 277 their suitability for MoT, such as Proof-of-Work (PoW), Proof-of-Stake (PoS), Byzantine Fault Tolerance (BFT) and their corresponding modifications [52].

2017 2nd International Conference on Advanced Information and Communication Technologies (AICT), 2017

The multi-homing technique in the dynamic spectrum access networks presents the key mechanism to ... more The multi-homing technique in the dynamic spectrum access networks presents the key mechanism to improve the overall spectrum utilization and social surplus of the end-users willing to communicate. In general, multi-homing allows the enduser to switch dynamically among the operators and together with other bunch of protocols are being developed in the IETF. They aim for better utilizing the network resources and thus improving the quality of service and experience (QoS/QoE) of the end-users. In our paper we present the agent-based application of the multi-homing technique, where the focus is paid on the investigation of the economy impacts on the overall network functioning of such a type. We show that the price-based demand evolution and price competition effects the network functioning only in the certain range of the network utilization. In this specific utilization range, the price competition, demand sensitivity and specific end-user's location work well, conforming with the known economic rules.

Rezumat. Acest articol cercetează elementele determinante ale investițiilor în Tunisia folosind d... more Rezumat. Acest articol cercetează elementele determinante ale investițiilor în Tunisia folosind date anuale pentru perioada 1961-2011. Importanța acestui studiu este dată de necesitatea determinării factorilor importanți care influențează investițiile locale în Tunisia. Este folosit un model de autoregresie pe intervale distribuite (ARDL) pentru a investiga impactul produsului intern brut, a bazei monetare și a deschiderii spre comerț asupra investițiilor locale. Rezultatele arată că există o relație de echilibru între investiții și baza monetară, în timp ce influența celorlalți factori este nesemnificativă sau ambiguă.

Multi-Agent Systems and Agreement Technologies, 2017

We present the agent-based model of the real-time spectrum trading market. Real-time means that t... more We present the agent-based model of the real-time spectrum trading market. Real-time means that the frequency spectrum is allocated to the operators in real-time and thus, the capacities of the operators are dynamically varying. The agent-based model consists of the two levels. The first level (the wholesale market) deals with the spectrum distribution towards the operators, where the operators compete for the spectrum resources. The second level (the retail market) presents the place where the operators compete with each-other to provide their services to the end-users. In our model, the operators are assumed to be heterogeneous in terms of the quality of service (QoS) perception. The heterogeneity of the operators exists due to the different placement of their base-stations (BTSs) in the investigated region. The BTS in the middle of the region is naturally favored, because of the unique spectral efficiency it provides to the end-users. We numerically analyze the volumes of the frequency spectra purchased by the operators, average revenue and the retail price of the operators under the consideration of three different pricing mechanisms.

Dataset consists of financial ratios up to three years prior evaluation year for firms divided in... more Dataset consists of financial ratios up to three years prior evaluation year for firms divided into four industries (retail, agriculture, manufacture, construction) for four evaluation years (2013, 2014, 2015, 2016).

The paper explores the asymmetric relation between public debt and economic growth in 13 EU count... more The paper explores the asymmetric relation between public debt and economic growth in 13 EU countries in the period 1993–2013. A panel data model uncovers a linear relation between debt-toGDP decrease and GDP growth, while the relation between the debt-to-GDP increase and GDP growth is defined by an inverted U-shaped curve (parabola) with the peak at a 64% debt-to-GDP ratio. We identified two main patterns in relations between debt-to-GDP and GDP growth: (i.) hysteresis loop – country data trace the closed circle defined within the debt interval [53%,113%] (Austria, Finland, Denmark) and (ii.) debt trap – country debt-to-GDP ratio breaks the 113% level and indebtedness increase followed by the GDP fall is tracing the diverging tail of parabola (debt trap in Greece, Italy, Portugal)

Symmetry, 2017

Modern 5G networks offer a large space for innovation and a completely new approach to addressing... more Modern 5G networks offer a large space for innovation and a completely new approach to addressing network functioning. A fixed spectrum assignment policy is a significant limitation of today's wireless communication network practice and is to be replaced by a completely new approach called dynamic spectrum access (DSA). However, there is no general agreement on the organization of the DSA. Some studies suggest that open access market can be inspired by the electricity or financial markets. It allows to treat operators with region coverage as investors entering the market and trading the spectra on an on-demand basis. Because investors operate in both the financial markets and the markets for spectra, new interference between both markets emerges. Our paper shows how the risk-free rate of return stemming from the financial markets influences the techno-economic properties of the network. We show that, for low risk-free returns, the spectrum market becomes oversupplied, which keeps service prices very low and spectrum trading volumes large. In contrast, if risk-free returns are high, then spectrum trading volumes decline and the market becomes price sensitive; in other words, economic rules begin to work better.

Data in Brief, 2019

Bankruptcy prediction is a long-standing issue that receives significant attention of academic re... more Bankruptcy prediction is a long-standing issue that receives significant attention of academic researchers and industry practitioners. Most of the papers on bankruptcy prediction focus on companies that are listed on the stock market, and there are only limited data for the rest of the companies. These companies, not indexed at any stock market, represent a significant part of the economy. The presented dataset consists of financial ratios of Slovak companies. There are 21 distinctive financial ratios which are available for three consecutive years prior to evaluation year in which companies may have filed for bankruptcy or not. The companies come from four different industries-agriculture, construction, manufacture, retail. We provide data for four consecutive years 2013e2016 for each industry. All companies are categorized as small-medium enterprises according to EU classification. Prediction performance results on this dataset are published in the research paper "Bankruptcy prediction for small-and medium-sized companies using severely imbalanced datasets" (Zori c ak et al., 2019).

EURASIP Journal on Wireless Communications and Networking, 2013

We propose and numerically analyze an agent-based simulation model of the spectrum frequency trad... more We propose and numerically analyze an agent-based simulation model of the spectrum frequency trading mechanism, where the heterogeneous agents take on the role of primary users. The interactions with the demand of the secondary users are considered. The model is constructed on the basis of Bak-Sneppen model of coevolution where the extremal dynamics is used to activate the low profitable users. Here, the strategies of the primary users are coevolving. They are characterized by the spectrum prices and cooperation intensity levels. The primary users interact indirectly by means of the demand stimulation of the secondary users and an insurance pool, which is provided by the spectrum exchange management system. The existence of the insurance pool is motivated by the needs of avoidance of the financial losses. The simulation results indicate the reliability of the insurance mechanism. In addition, several notable phenomena have emerged from the interactions of agents. The price increase resulting from the spontaneously formed oligopolistic practices of agents is considered as the most emergent feature of the model.

Mpra Paper, 2014

Despite the efficient market hypothesis (EHM), lead-lag relationships can be observed mainly betw... more Despite the efficient market hypothesis (EHM), lead-lag relationships can be observed mainly between financial derivatives and underlying asset prices, prices of large and small companies, etc. In our paper, we examined the leadlag relationship between prices of open ended funds and an all-share index as a representative of the capital market. Along with more traditional methods of using cross correlations, partial correlation and Toda-Yamamoto causality tests, we also analysed the speed of adjustment of assets to their intrinsic values and identified the most prevalent lag using rolling time windows. The analysis was performed using data from the South Africa capital market.

2019 3rd International Conference on Advanced Information and Communications Technologies (AICT), 2019

Small cells are considered as a key solution to accommodate the rapidly growing end-user demand a... more Small cells are considered as a key solution to accommodate the rapidly growing end-user demand and the associated ever-increasing traffic load. They are expected to provide fast and low-cost expansion of existing networks, improvement of throughput along with power reduction in mobile equipment. The small cells will offload users from the congested macrocell network, enhance their quality of service and dramatically increase the overall system capacity through the concept of frequency reuse. In this paper, an agent-based model is proposed to investigate economic aspects of deployment of femtocell operators as well as spectrum leasing in mobile heterogeneous networks. Process of leasing price formation is modelled as a continuous double auction, where the transaction price is a result of the bargaining process that takes place between macrocell and femtocell operators. Simulation results show that spectrum leasing can be beneficial for both types of operators and also for end-users that can enjoy a higher quality of service. As a result, higher spectrum usage and a number of connections can be achieved, which is one of the main reasons for introducing femtocells in the network.

Journal of Economic Interaction and Coordination, 2012

This article proposes a model of a simple economy based on a set of agent-based modeling principl... more This article proposes a model of a simple economy based on a set of agent-based modeling principles. The model is based on the “trust game” formulated by Berg et al. (Games Econ Behav 10:122–142, 1995), and anticipates a random matching of partners taking in to account adaptive agent behavior. Simulation in the NetLogo programming environment, using profile distributions obtained from empirical studies, has shown the most successful agents to posses low parameters of trust in the role of Sender and high parameters of trustworthiness in the role of Receiver.