689 research outputs found
The Statistics of <i>q</i>-Statistics
No full textAlmost two decades ago, Ernesto P. Borges and Bruce M. Boghosian embarked on the intricate task of composing a manuscript to honor the profound contributions of Constantino Tsallis to the realm of statistical physics, coupled with a concise exploration of q-Statistics. Fast-forward to Constantino Tsallis’ illustrious 80th birthday celebration in 2023, where Deniz Eroglu and Ugur Tirnakli delved into Constantino’s collaborative network, injecting renewed vitality into the project. With hearts brimming with appreciation for Tsallis’ enduring inspiration, Eroglu, Boghosian, Borges, and Tirnakli proudly present this meticulously crafted manuscript as a token of their gratitude
The Effect of Link Modifications on Network Synchronization
No full textA major issue in studying complex network systems, such as neuroscience and power grids, is understanding the response of network dynamics to link modifications. The notion of network G(G, f, H) refers to di↵usively coupled identical oscillators, where isolated dynamics are chosen to be chaotic. As a consequence of the di↵usive nature, a globally synchronized state emerges as an invariant synchronization subspace, and it will be locally stable above critical coupling strength. Furthermore, the real part of the second minimum eigenvalue of the Laplacian matrix is inverse proportional to the critical coupling strength. Thus, we can use it to determine the synchronizability between two networks. Due to the asymmetry of the Laplacian matrix of a directed graph, adding directed links might cause a decrease in the real part of the second minimum eigenvalue of the Laplacian. If, after adding a link to a graph in a given network, the real part of the second minimum eigenvalue of the Laplacian matrix increases, it is called the enhancement of synchronization. Otherwise, it is called the hindrance of synchronization. In this research, we explore how the stability of synchronization at di↵usively coupled oscillators is a↵ected by link modifications for the networks created using particular motifs, i.e., cycle and star motifs. We consider a weakly connected directed graph consisting of two strongly connected components connected by directed link(s) (called cutset). We study the synchronization transitions in such networks when new directed link(s) between the components, in the opposite direction of the cutset, is added and strongly connects the whole network. We explore which properties of underlying graphs and their connected components may hinder or enhance the synchronization
Generalized Synchronization: Master-Slave Relationship in Three Coupled Systems
No full textSynchronization is an important phenomenon for complex, biological, and physical systems such as the brain, i.e., Parkinson’s disease, heart beating, hand-clapping, power grids, lasers, and many others. Intuitively, we can express synchronization as strong correlations between coupled systems. We can state two scenarios in this manner. One is synchronization between identical systems, which is called complete synchronization; the other is the synchronization between the non-identical systems, called generalized synchronization. In this thesis, initially, we considered the two coupled systems and calculated the critical coupling value for the generalized synchronization analytically. More precisely, the Lorenz system drives two R¨ossler systems. We investigated the critical coupling value for synchronization numerically. However, real-world examples are much more complex. The most straightforward case was the two coupled systems for the generalized synchronization, and next, we focus on three coupled systems. In particular, suppose that we have three coupled one Lorenz and two R¨ossler systems. In our example, the Lorenz system drives the first R¨ossler system, and first R¨ossler system drives the second R¨ossler system, and finally, the second R¨ossler system also drives the Lorenz system. We calculated the critical coupling of the whole system for generalized synchronization and analyzed the time series for each system
Security analysis of revocable and bipartite biotokens
No full textNeyire Deniz Sarıer (Saner) (MEF Author)##nofulltext##In this paper, we analyze the security of bipartite biotokens that release a secret key hidden in the biotoken by using biometrics. We show that the biotoken encoding of 80/112/128-bit symmetric encryption keys are vulnerable to brute force attacks, whose complexity is lower than cryptographic security. Also, we present the weaknesses in the design of revocable biotokens that form the basis for bipartite biotokens. Finally, we propose countermeasures to prevent these attacks and discuss the employment of other efficient cryptographic techniques that possess provable security guarantees.WOS:0003760875000142-s2.0-84966839172Conference Proceedings Citation Index- ScienceProceedings PaperKasımYÖK - 2015-1
Deniz: A Robust Bidding Strategy for Negotiation Support Systems
No full textThis paper presents the Deniz agent that has been specifically designed to support human negotiators in their bidding. The design of Deniz is done with the criteria of robustness and the availability of small data, due to a small number of negotiation rounds in mind. Deniz’s bidding strategy is based on an existing optimal concession strategy that concedes in relation to the expected duration of the negotiation. This accounts for the small data and small number of rounds. Deniz deploys an adaptive behavior-based mechanism to make it robust against exploitation. We tested Deniz against typical bidding strategies and against human negotiators. Our evaluation shows that Deniz is robust against exploitation and gains statistically significant higher utilities than human test subjects, even though it is not designed specifically to get the highest utility against humans.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Interactive Intelligenc
Regime Switching in Coupled Nonlinear Systems: Sources, Prediction, and Control-Minireview and Perspective on the Focus Issue
No full textEroglu, Deniz/0000-0001-6725-6949Regime switching, the process where complex systems undergo transitions between qualitatively different dynamical states due to changes in their conditions, is a widespread phenomenon, from climate and ocean circulation, to ecosystems, power grids, and the brain. Capturing the mechanisms that give rise to isolated or sequential switching dynamics, as well as developing generic and robust methods for forecasting, detecting, and controlling them is essential for maintaining optimal performance and preventing dysfunctions or even collapses in complex systems. This Focus Issue provides new insights into regime switching, covering the recent advances in theoretical analysis harnessing the reduction approaches, as well as data-driven detection methods and non-feedback control strategies. Some of the key challenges addressed include the development of reduction techniques for coupled stochastic and adaptive systems, the influence of multiple timescale dynamics on chaotic structures and cyclic patterns in forced systems, and the role of chaotic saddles and heteroclinic cycles in pattern switching in coupled oscillators. The contributions further highlight deep learning applications for predicting power grid failures, the use of blinking networks to enhance synchronization, creating adaptive strategies to control epidemic spreading, and non-feedback control strategies to suppress epileptic seizures. These developments are intended to catalyze further dialog between the different branches of complexity.Institute of Physics Belgrade; Ministry of Science, Technological Development and Innovation of the Republic of Serbia [119F125, 121F329]; TUBITAK; BAGEP Award of the Science Academy, TurkeyI.F. acknowledges the funding from the Institute of Physics Belgrade through grant by the Ministry of Science, Technological Development and Innovation of the Republic of Serbia. D.E. acknowledges support of TUBITAK (Grant Nos. 119F125 and 121F329) and the BAGEP Award of the Science Academy, Turkey.Science Citation Index Expande
The Pitfalls of Secularism in Turkey: An Interview with Deniz Kandiyoti
No full textDeniz Kandiyoti is Emeritus Professor of Development Studies at the School of Oriental and African Studies, University of London. Her work on gender, development, nationalism, and Islam has been deeply influential within feminist studies, development studies and Middle Eastern studies. Her path-breaking essay ‘Bargaining with Patriarchy’ appeared in the journal Gender and Society in 1988. She is the author of Concubines, Sisters and Citizens: Identities and Social Transformation (1997) and the editor of Fragments of Culture: The Everyday Life of Modern Turkey (2002), Gendering the Middle East (1996), Women, Islam and the State (1991)
Doğuş himota insansız deniz taşıtı
No full textTüzel, Nuri (Dogus Author) -- Akıncı, Gürcan Şahin (Dogus Author) -- Tükel, Dilek (Dogus Author) -- Conference full title: Elektrik Elektronik Mühendisliği Kongresi, EEMKON 2017: İstanbul, Türkiye, 16-18 Kasım 2017.İnsansız deniz araçları, insanlı araçlarla yapılamayacak askeri operasyonlarda veya insan hayatını riske eden görevlerde yer alabilmektedir. Projemizin hedefi Raspberry Pi 3 kullanarak insansız deniz aracı yapmaktır. Aracımız operatör tarafından manüel olarak veya önceden belirlenmiş yörüngeleri otomatik olarak takip edebilme yeteneğine sahiptir.Unmanned sea vehicles have the potential, and in some cases the demonstrated ability, to reduce risk to manned forces to accomplish military missions, perform tasks. Our project mission is to develop an unmanned sea vehicle that have onboard PC-based Raspberry Pi 3 controller. Dogus Himota USV can be operated manually or it can follow autonomously predetermined trajectories
Cyclic and monotonic compression behavior of CFRP-jacketed damaged noncircular concrete prisms
No full textKorhan Deniz Dalgıç (MEF Author)This paper focuses on rehabilitation/strengthening of damaged concrete prisms through external carbon-fiber-reinforced polymer (CFRP) jacketing. In order to evaluate the efficiency of the strengthening method on the damaged concrete prisms, an experimental study including 22 concrete prisms with square and rectangular cross sections was carried out. The parameters of the experimental study are the damage levels. Furthermore, effects of loading scheme (monotonic or cyclic) and cross section type (square and rectangular) were investigated in the existence of damage. The concrete prisms were tested under compression stresses up to three specified axial deformation levels to be representative of slight, moderate, and severe compression damages before strengthening. Tests were repeated after rehabilitation/strengthening of damaged specimens with CFRP jacketing. Test results showed that CFRP rehabilitation/strengthening was effective on enhancement of strength and deformability of the damaged concrete prisms. However, the efficiency of the strengthening method in terms of compressive strength tended to reduce when the level of damage increased. Furthermore, an available model is modified to include the effects of damage level, and the modified model is shown to produce accurate results. (C) 2015 American Society of Civil Engineers.WOS:0003700801000262-s2.0-84955616918Science Citation Index ExpandedArticleUluslararası işbirliği ile yapılmayan - HAYIRŞubatYÖK - 2015-1
Measurement of cognitive dynamics during video watching through event-related potentials (ERPs) and oscillations (EROs)
No full textEvent-related potentials (ERPs) and oscillations (EROs) are reliable measures of cognition, but they require time-locked electroencephalographic (EEG) data to repetitive triggers that are not available in continuous sensory input streams. However, such real-life-like stimulation by videos or virtual-reality environments may serve as powerful means of creating specific cognitive or affective states and help to investigate dysfunctions in psychiatric and neurological disorders more efficiently. This study aims to develop a method to generate ERPs and EROs during watching videos. Repeated luminance changes were introduced on short video segments, while EEGs of 10 subjects were recorded. The ERP/EROs time-locked to these distortions were analyzed in time and time-frequency domains and tested for their cognitive significance through a long term memory test that included frames from the watched videos. For each subject, ERPs and EROs corresponding to video segments of recalled images with 25% shortest and 25% longest reaction times were compared. ERPs produced by transient luminance changes displayed statistically significant fluctuations both in time and time-frequency domains. Statistical analyses showed that a positivity around 450 ms, a negativity around 500 ms and delta and theta EROs correlated with memory performance. Few studies mixed video streams with simultaneous ERP/ERO experiments with discrete task-relevant or passively presented auditory or somatosensory stimuli, while the present study, by obtaining ERPs and EROs to task-irrelevant events in the same sensory modality as that of the continuous sensory input, produces minimal interference with the main focus of attention on the video stream
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