22 results on '"Sirakoulis, Georgios Ch."'
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2. Hitting times of quantum and classical random walks in potential spaces
- Author
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Varsamis, Georgios D., Karafyllidis, Ioannis G., and Sirakoulis, Georgios Ch.
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- 2022
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3. Light sensitive Belousov–Zhabotinsky medium accommodates multiple logic gates
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Tsompanas, Michail-Antisthenis, Fyrigos, Iosif-Angelos, Ntinas, Vasileios, Adamatzky, Andrew, and Sirakoulis, Georgios Ch.
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- 2021
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4. Cellular non-linear network model of microbial fuel cell
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Tsompanas, Michail-Antisthenis, Adamatzky, Andrew, Ieropoulos, Ioannis, Phillips, Neil, Sirakoulis, Georgios Ch., and Greenman, John
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- 2017
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5. On plant roots logical gates
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Adamatzky, Andrew, Sirakoulis, Georgios Ch., Martínez, Genaro J., Baluška, Frantisek, and Mancuso, Stefano
- Published
- 2017
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6. A MapReduce scratchpad memory for multi-core cloud computing applications
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Kachris, Christoforos, Sirakoulis, Georgios Ch., and Soudris, Dimitrios
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- 2015
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7. Design automation of cellular neural networks for data fusion applications
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Chatziagorakis, Prodromos, Sirakoulis, Georgios Ch., and Lygouras, John N.
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- 2012
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8. A novel cellular automata based technique for visual multimedia content encryption
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Chatzichristofis, Savvas A., Mitzias, Dimitris A., Sirakoulis, Georgios Ch., and Boutalis, Yiannis S.
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- 2010
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9. Real-time disparity map computation module
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Georgoulas, Christos, Kotoulas, Leonidas, Sirakoulis, Georgios Ch., Andreadis, Ioannis, and Gasteratos, Antonios
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- 2008
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10. A bio-inspired multi-camera system for dynamic crowd analysis
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Chrysostomou, Dimitrios, Sirakoulis, Georgios Ch., and Gasteratos, Antonios
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- 2014
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11. Spatial games and memory effects on crowd evacuation behavior with Cellular Automata.
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Mitsopoulou, Martha, Dourvas, Nikolaos I., Sirakoulis, Georgios Ch., and Nishinari, Katsuhiro
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COLLECTIVE behavior ,CELLULAR automata ,SPATIAL memory ,SPATIAL behavior ,URBAN growth ,DYNAMIC models - Abstract
• Cellular Automata (CA) modeling of crowd evacuation behavior with spatial game. • Novel long memory CA based approach models in a fully dynamic way crowd behavior. • Realistic crowd modeling by incorporating more than one velocity for moving agents. • Multi-parameter modeling including level of emergency, and previous games outcome. • Study of people behavior and choice of possible strategy in subsequent conflicts. When it comes to emergency evacuations of a big number of individuals from a certain room or a building, it is crucial that they should be able to exit the under study place in a quick and safe manner. Nevertheless, crowd behavior can be affected from various factors, among which are the distance from the exit, the visibility of the exit, the density of the crowd and how uncomfortable the conditions are inside the room for the crowd. In this study, we propose an evacuation model, in order to achieve a computationally enhanced simulation, based on Cellular Automata modeling, coupled with a Spatial Game to solve conflict situations among the anxious crowd. Additionally, aiming to a more realistic model, we added not only topological, but also behavioral characteristics coupled with the incorporation of different moving velocities and memory features to the evacuees. [ABSTRACT FROM AUTHOR]
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- 2019
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12. Accelerating fuzzy cellular automata for modeling crowd dynamics.
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Gerakakis, Ioannis, Gavriilidis, Prodromos, Dourvas, Nikolaos I., Georgoudas, Ioakeim G., Trunfio, Giuseppe A., and Sirakoulis, Georgios Ch.
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CELLULAR automata ,GRAPHICS processing units ,FUZZY logic - Abstract
• Graphics Processing Unit Acceleration of Fuzzy Cellular Automata for crowd evacuation. • Significant speed up of Fuzzy Cellular Automata execution of two orders of magnitude. • Fuzzy logic velocity adjustments and selection of direction experimentally proven efficient. • Incorporation of psychological-impact feature in Fuzzy Cellular Automata model. • Speed and flow vs. time diagrams for validation of model's successful response. Pedestrian and crowd dynamics are physical phenomena that are fundamentally characterized by non-linear complexity. In the same time, the need of modern way of living seeks for such dynamics real time modeling also enabling computationally efficient and affordable solutions for sake of safety and easiness of people located in gathering places all over the world. Towards this direction, Cellular Automata (CAs), a parallel computational model combining macro- and microscopic inherent attributes that could severely help with adequate modeling of the aforementioned dynamics, are one of the best compromises among different competing computational techniques. In order to overcome CAs deterministic nature, in this paper the incorporation of fuzzy logic principles in a CA model that simulates crowd dynamics and crowd evacuation processes, with the usage of a Mamdani type fuzzy inference system, is proposed. More specifically, basic concepts of fuzzy logic such as linguistic variables and if-then rules are attributed to the proposed CA model to preserve fuzzy consequents and fuzzy antecedents thus resulting in a realistic and rather efficient modeling approach. Furthermore, in the paper the implementation of fuzziness in CA dynamics is tackled with the acceleration of the proposed model through fully parallel execution on Graphics Processing Units (GPU). The GPU implementation of the fuzzy CA model is analyzed in full detail and stressed against CPU corresponding implementation resulting to an important speed up of fuzzy CA execution. This is further explored through the GPU applications of the fuzzy CA model in a real building, namely the museum 'CONSTANTIN XENAKIS', in Serres, Greece. [ABSTRACT FROM AUTHOR]
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- 2019
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13. Parallel fuzzy cellular automata for data-driven simulation of wildfire spreading.
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Ntinas, Vasileios G., Moutafis, Byron E., Trunfio, Giuseppe A., and Sirakoulis, Georgios Ch.
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PARALLEL algorithms ,FUZZY systems ,CELLULAR automata ,WILDFIRES ,COMPUTER simulation ,COMPUTATIONAL complexity - Abstract
Cellular Automata (CA) have been introduced many decades ago as one of the most efficient parallel computational models able to simulate various physical processes and systems where the interactions are local. In this paper, we are trying to advance the application of CA in modeling wildfires by accounting for the fuzziness intrinsic to the numerous environmental variables and mechanisms engaged with the emergence of the phenomenon itself. The proposed Fuzzy CA (FCA) model adopts a data-driven approach, based on evolutionary optimization, which allows incorporating knowledge from real wildfires in order to enhance its accuracy. The main difficulty for doing so arrives from the computational complexity of the proposed framework and the burden of computational resources needed for its application, which would prevent the real-time prediction of fire spread scenarios. In order to tackle the aforementioned difficulties, we propose model's fully parallel implementations in Graphical Processing Units (GPUs) and Field Programmable Gate Arrays (FPGAs) hardware. In the article, we first investigate the speedup achieved by the developed parallel implementations. Then, we present and discuss two applications to heterogeneous landscapes through comparisons with observed wildfires. Moreover, we compare the proposed framework with two different modelling approaches and results found are really promising. [ABSTRACT FROM AUTHOR]
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- 2017
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14. Building exploration with leeches Hirudo verbana.
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Adamatzky, Andrew and Sirakoulis, Georgios Ch.
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HIRUDO , *BUILDINGS & the environment , *BUILDING evacuation , *ELECTROMAGNETIC fields , *RESCUES , *BUILDING layout , *SOCIAL dynamics - Abstract
Safe evacuation of people from building and outdoor environments, and search and rescue operations, always will remain actual in course of all socio-technological developments. Modern facilities offer a range of automated systems to guide residents towards emergency exists. The systems are assumed to be infallible. But what if they fail? How occupants not familiar with a building layout will be looking for exits in case of very limited visibility where tactile sensing is the only way to assess the environment? Analogous models of human behaviour, and socio-dynamics in general, are provided to be fruitful ways to explore alternative, or would-be scenarios. Crowd, or a single person, dynamics could be imitated using particle systems, reaction–diffusion chemical medium, electro-magnetic fields, or social insects. Each type of analogous model offer unique insights on behavioural patterns of natural systems in constrained geometries. In this particular paper we have chosen leeches to analyse patterns of exploration. Reasons are two-fold. First, when deprived from other stimuli leeches change their behavioural modes in an automated regime in response to mechanical stimulation. Therefore leeches can give us invaluable information on how human beings might behave under stress and limited visibility. Second, leeches are ideal blueprints of future soft-bodied rescue robots. Leeches have modular nervous circuitry with a rich behavioral spectrum. Leeches are multi-functional, fault-tolerant with autonomous inter-segment coordination and adaptive decision-making. We aim to answer the question: how efficiently a real building can be explored and whether there any dependencies on the pathways of exploration and geometrical complexity of the building. In our case studies we use templates made on the floor plan of real building. [ABSTRACT FROM AUTHOR]
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- 2015
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15. Memristor-based combinational circuits: A design methodology for encoders/decoders.
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Vourkas, Ioannis and Sirakoulis, Georgios Ch.
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MEMRISTORS , *ELECTRONIC circuits , *DECODERS (Electronics) , *DECODERS & decoding , *NANOTECHNOLOGY , *NANOELECTRONICS - Abstract
Abstract: The crossbar architecture is viewed as the most likely path towards novel nanotechnologies which are expected to continue the technological revolution. Memristor-based crossbars for integrating memory units have received considerable attention, though little work has been done concerning the implementation of logic. In this work we focus on memristor-based complex combinational circuits. Particularly, we present a design methodology for encoder and decoder circuits. Digital encoders are found in a variety of electronics multi-input combinational circuits (e.g. keyboards) nowadays, converting the logic level ‘1’ data at their inputs into an equivalent binary code at the output. Their counterparts, digital decoders, constitute critical components for nanoelectronics, mainly in peripheral/interface circuitry of nanoelectronic circuits and memory structures. The proposed methodology follows a CMOS-like design scheme which can be used for the efficient design and mapping of any 2 n ×n (n×2 n ) encoder (decoder) onto the memristor-based crossbar geometry. For their implementation, a hybrid nano/CMOS crossbar type with memristive cross-point structures and available transistors is elaborated, which is a promising solution to the interference between neighboring cross-point devices during access operation. Circuit functionality of the presented encoder/decoder circuits is exhibited with simulations conducted using a simulator environment which incorporates a versatile memristor device model. The proposed design and implementation paradigm constitutes a step towards novel computational architectures exploiting memristor-based logic circuits, and facilitating the design and integration of memristor-based encoder/decoder circuits with nanoelectronics applications of the near future. [Copyright &y& Elsevier]
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- 2014
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16. An FPGA processor for modelling wildfire spreading
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Progias, Pavlos and Sirakoulis, Georgios Ch.
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FIELD programmable gate arrays , *MICROPROCESSORS , *WILDFIRES , *CELLULAR automata , *COMPUTER software , *VHDL (Computer hardware description language) - Abstract
Abstract: In this paper, a model based on Cellular Automata (CAs) for predicting wildfire spreading is presented. The proposed model is inspired by existing fire spread models, but also includes a number of changes and additions, compared to them. Primary goal of the paper is to design and implement a software-based model as well as a corresponding hardware-based one that will sufficiently describe real fires, but will also have less stringent requirements on computational resources and computational power for execution. Therefore, an effort has been made to minimize the complexity of the model and the resulting computational burden aiming at an implementation that will have a practical significance in predicting the evolution of a fire. The proposed model is implemented on an Altera®Stratix IV®FPGA (Field-Programmable Gate Array), designed to execute in a parallel way in order to produce valuable information in real time that can be used to optimize response to a fire crisis. The FPGA design results from the automatically produced synthesizable VHDL code of the CA model and is advantageous in terms of low-cost, high speed and portability. The resulting implementation sufficiently depicts the natural phenomenon of wildfire spreading and provides short calculation times. Finally, the presented FPGA implementation of the proposed CA model offers the possibility a portable system to be designed, connected with GPS as well as GIS and/or wind monitoring systems able to provide real-time information concerning the wildfire propagation on the under test area. [Copyright &y& Elsevier]
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- 2013
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17. Modeling employees behavior in workplace dynamics.
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Saravakos, Petros and Sirakoulis, Georgios Ch.
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WORK environment ,CELLULAR automata ,EMPLOYEE psychology ,STOCHASTIC models ,ROBUST control - Abstract
During the past years, Cellular Automata (CAs) have been extensively used for modeling of many complex systems and processes with great success. In this paper, we study a Cellular Automaton (CA) model for the influence of employees' behavior in a parameterized workplace environment taking into account different behavioral characteristics. In specific, we model employees' interactions based on their influence radius, the degree of their willingness on adaption of organizational norms and the employee's attitude in general in the under study workplace. The proposed CA model is taking into account employee loyalty, a combined statistic of the employee behavior and her/his insistence and company policies applied to the employees so as to restrain unwanted or impose desirable behavioral patterns in correspondence to the organization norms. Conclusively, the CA model facilitates the presentation and simulation of a workplace with a variety of employee behavioral characteristics and under adaptable company policies. Different workplaces were used to illustrate the simulation of employee behavior with CA model. As a result, the proposed model was practically used on two levels, firstly to estimate the workplace robustness and secondly to illustrate workspace dynamics. Finally, the CA model has been utilized to simulate behavioral patterns at a small enterprise in Greece. In specific, based on the employees answers to detailed surveys the CA model was initialized and then applied to describe the behavioral traits of the under study company employees. Finally, the proposed model, in all the examined cases can be utilized in conjunction with applied employee management techniques to facilitate managerial decisions and forecast the impact of employee behavioral changes and company decisions. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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18. Cellular Automata Applications for Research and Industry.
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Wąs, Jarosław and Sirakoulis, Georgios Ch.
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CELLULAR automata ,APPLICATION software ,MATHEMATICAL proofs ,HIGH performance computing ,ROBUST control ,GRAPHICS processing units - Abstract
For several decades the Cellular Automata (CA) modeling approach has been proven to be self-sufficient to inspire modelers and practitioners on how to apply successfully their ideas on modern computational platforms by using their inherent parallelism enabling high performance computing and modeling. One can easily describe CA as a mature parallel computational system robust enough to evolve or better say to adapt itself to the new computing paradigms of multiprocessors and graphical processing units with noteworthy efficacy and admirable modeling results. This Special Section is exactly dedicated to the application of CA paradigm to research and industry containing extended versions of papers originally published in proceedings of 11th International Conference on Cellular Automata for Research and Industry (ACRI 2014), a biannual conference dedicated to CA theory and applications, including also papers submitted in reference to the corresponding open Call for Papers in the context of Journal of Computational Science . [ABSTRACT FROM AUTHOR]
- Published
- 2015
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19. Conway's Game of Life in Quantum-dot Cellular Automata.
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Liolis, Orestis, Sirakoulis, Georgios Ch., and Adamatzky, Andrew
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CELLULAR automata , *MOORE'S law , *FAULT-tolerant computing , *ENERGY consumption - Abstract
Quantum-dot Cellular Automata (QCA) technology has been considered as one promising solution to deal with the beyond Moore's law and after von Neumann's computing architecture issues, bringing advantages such as high performance and low energy consumption. In this paper, we focus on the implementation in QCA technology of one of the most well-known Cellular Automaton (CA), namely the Game of Life (GoL). GoL introduced by John Conway is one of the most interesting CA, due to the abilities of self-production and computational universality. In this work, a novel fault-tolerant implementation of GoL in programmable crossbar architecture is proposed delivering the computation universality of the GoL in a plausible way. For the provided design, fault-tolerant majority and inverter gates are also presented in a programmable crossbar architecture. Such an implementation provides the QCA circuits designers with an almost endless library of ready-to-use applications, in various scientific fields. Extensive performance evaluation coupled with appropriate simulation results validate the efficacy of the proposed QCA design depicting appropriately the inherent complexity of the GoL rules and structures. [ABSTRACT FROM AUTHOR]
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- 2021
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20. Computational structures and methods with memristive devices and systems.
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Sirakoulis, Georgios Ch. and Lehtonen, Eero
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MEMRISTORS , *COMPUTER architecture , *COMPUTATIONAL complexity , *COMPUTER systems , *ELECTRONIC circuits - Published
- 2014
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21. Multi-level resistance switching and random telegraph noise analysis of nitride based memristors.
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Vasileiadis, Nikolaos, Loukas, Panagiotis, Karakolis, Panagiotis, Ioannou-Sougleridis, Vassilios, Normand, Pascal, Ntinas, Vasileios, Fyrigos, Iosif-Angelos, Karafyllidis, Ioannis, Sirakoulis, Georgios Ch., and Dimitrakis, Panagiotis
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RANDOM noise theory , *SILICON nitride films , *COPPER films , *MEMRISTORS , *SILICON nitride , *NITRIDES , *METALLIC oxides - Abstract
Resistance switching devices are of special importance because of their application in resistive memories (RRAM) which are promising candidates for replacing current nonvolatile memories and realize storage class memories. These devices exhibit usually memristive properties with many discrete resistance levels and implement artificial synapses. The last years, researchers have demonstrated memristive chips as accelerators in computing, following new in-memory and neuromorphic computational approaches. Many different metal oxides have been used as resistance switching materials in MIM or MIS structures. Understanding of the mechanism and the dynamics of resistance switching is very critical for the modeling and use of memristors in different applications. Here, we demonstrate the bipolar resistance switching of silicon nitride thin films using heavily doped Si and Cu as bottom and top-electrodes, respectively. Analysis of the current-voltage characteristics reveal that under space-charge limited conditions and appropriate current compliance setting, multi-level resistance operation can be achieved. Furthermore, a flexible tuning protocol for multi-level resistance switching was developed applying appropriate SET/RESET pulse sequences. Retention and random telegraph noise measurements performed at different resistance levels. The present results reveal the attractive properties of the examined devices. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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22. Memristive learning cellular automata for edge detection.
- Author
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Karamani, Rafailia-Eleni, Fyrigos, Iosif-Angelos, Tsakalos, Karolos-Alexandros, Ntinas, Vasileios, Tsompanas, Michail-Antisthenis, and Sirakoulis, Georgios Ch.
- Subjects
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CELLULAR automata , *EDGE detection (Image processing) - Abstract
Memristors have been utilized as an unconventional computational substrate and gained interest as a medium to implement neuromorphic computations. A mathematical model that also proved its potential is Learning Cellular Automata, that is an amalgam of Cellular Automata and Learning Automata. The realization of the common characteristics of memristive circuits and Learning Cellular Automata can only lead to their combination. Namely, both manage to blend storage and processing capabilities in their basic entity. This study involves the definition of memristive circuits that realize the computing behavior of Learning Cellular Automata. An example of this methodology is provided with the description of the implementation of edge detection for image processing. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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