Browsing by Subject "Consensus"
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Item Open Access Consensus as a Nash equilibrium of a dynamic game(IEEE, 2016) Niazi, Muhammad Umar B.; Özgüler, Arif Bülent; Yıldız, AykutConsensus formation in a social network is modeled by a dynamic game of a prescribed duration played by members of the network. Each member independently minimizes a cost function that represents his/her motive. An integral cost function penalizes a member's differences of opinion from the others as well as from his/her own initial opinion, weighted by influence and stubbornness parameters. Each member uses its rate of change of opinion as a control input. This defines a dynamic non-cooperative game that turns out to have a unique Nash equilibrium. Analytic explicit expressions are derived for the opinion trajectory of each member for two representative cases obtained by suitable assumptions on the graph topology of the network. These trajectories are then examined under different assumptions on the relative sizes of the influence and stubbornness parameters that appear in the cost functions.Item Open Access Distributed output feedback control of decomposable LPV systems with delay and switching topology: application to consensus problem in multi-agent systems(Taylor & Francis, 2020-01-08) Zakwan, Muhammad; Ahmed, SaeedThis paper presents distributed output feedback control of a class of distributed linear parameter varying systems with switching topology and parameter varying time delay. To formulate the synthesis conditions for the distributed controller in terms of LMIs, the delay dependent bounded-real lemma based on parameter-dependent Lyapunov–Krasovskii functionals is used. The efficacy of the result is illustrated by applying it to two real-world examples pertaining to the consensus problem of multi-agent systems.Item Open Access Evaluation of an aldo-keto reductase gene signature with prognostic significance in colon cancer via activation of epithelial to mesenchymal transition and the p70S6K pathway(Oxford University Press, 2020-07) Demirkol Canlı, S.; Seza, E. G.; Sheraj, I.; Gömçeli, İ.; Turhan, N.; Carberry, S.; Prehn, J. H. M.; Güre, Ali Osmay; Banerjee, S.AKR1B1 and AKR1B10, members of the aldo-keto reductase family of enzymes that participate in the polyol pathway of aldehyde metabolism, are aberrantly expressed in colon cancer. We previously showed that high expression of AKR1B1 (AKR1B1HIGH) was associated with enhanced motility, inflammation and poor clinical outcome in colon cancer patients. Using publicly available datasets and ex vivo gene expression analysis (n = 51, Ankara cohort), we have validated our previous in silico finding that AKR1B1HIGH was associated with worse overall survival (OS) compared with patients with low expression of AKR1B1 (AKR1B1LOW) samples. A combined signature of AKR1B1HIGH and AKR1B10LOW was significantly associated with worse recurrence-free survival (RFS) in microsatellite stable (MSS) patients and in patients with distal colon tumors as well as a higher mesenchymal signature when compared with AKR1B1LOW/AKR1B10HIGH tumors. When the patients were stratified according to consensus molecular subtypes (CMS), AKR1B1HIGH/AKR1B10LOW samples were primarily classified as CMS4 with predominantly mesenchymal characteristics while AKR1B1LOW/AKR1B10HIGH samples were primarily classified as CMS3 which is associated with metabolic deregulation. Reverse Phase Protein Array carried out using protein samples from the Ankara cohort indicated that AKR1B1HIGH/AKR1B10LOW tumors showed aberrant activation of metabolic pathways. Western blot analysis of AKR1B1HIGH/AKR1B10LOW colon cancer cell lines also suggested aberrant activation of nutrient-sensing pathways. Collectively, our data suggest that the AKR1B1HIGH/AKR1B10LOW signature may be predictive of poor prognosis, aberrant activation of metabolic pathways, and can be considered as a novel biomarker for colon cancer prognostication.Item Open Access On the Delay Margin for Consensus in Directed Networks of Anticipatory Agents(Elsevier B.V., 2016) Irofti D.; Atay, F. M.We consider a linear consensus problem involving a time delay that arises from predicting the future states of agents based on their past history. In case the agents are coupled in a connected and undirected network, the exact condition for consensus is that the delay be less than a constant threshold that is independent of the network topology or size. In directed networks, however, the situation is quite different. We show that the allowable maximum delay for consensus depends on the network topology in a nontrivial way. We study this delay margin in several network constellations, including various circulant networks with directed links. We show that the delay margin depends not only on the number of neighbors, but also on the directionality of connections with those neighbors. Furthermore, the delay margin improves as the circulant networks are rewired en route to a small-world configuration. © 2016Item Open Access Process oriented value judgments of actor groups in mass housing : the case of Eryaman fourth stage, Ankara(2004) Altay, CanThis study is an attempt to develop an understanding of the mass housing process, through establishing a wider perspective to acknowledge the contributions of various groups. The theoretical structure of the study is composed of understanding the life-cycle of building, and the appropriation of the social constructionist paradigm; as well as establishing value judgments as the tools of analysis. “Actor groups”, refer to the various social and professional groups who act within the process, whose values are formative of mass housing. Value judgments are proposed as the assertion and expression of values. Mass housing in Turkey, and the role of Housing Development Administration (HDA) is noted, followed by explaining the case of Eryaman as a demonstrational project by HDA. The fourth stage of Eryaman is focused on as it includes wider variety of actor groups with distinct roles. An exploratory part, an inquiry into the value judgments of executive policy makers, has been conducted. This is followed by a survey study where representatives of various actor groups are exposed to the derived value judgments. The results present situations that provide knowledge on various conflicts and values of groups. Conceptual contributions as well as insights on the case are provided, as schemes of process oriented value judgments, classified according to a hierarchical structure are proposed. The second conceptual contribution is the introduction of six conceptualizations for further studies of values in the building context, which are consensus, opposition, inter-group valuations, fields of authority, notions related to conjuncture, and internal polarizations within groups.Item Open Access Wisdom of group forecasts: Does role-playing play a role?(Pergamon Press, 2012) Önkal, D.; Sayım, K. Z.; Lawrence, M.Forecasting plays a special role in supply chain management with sales forecasts representing one of the key drivers for collaborative planning and decision making in the organisations involved. We review the important role played by judgemental forecasts in this area, focusing on group predictions. Noting the scarcity of research using group forecasts, we present the results of an experiment where consensus forecasts are elicited from structured groups with and without role-playing. Comparisons with groups without any assigned roles show that getting into tailored organisational roles does have a significant effect in the resultant forecasts. In particular, members of the role-playing groups show less agreement with consensus forecasts and display a strong commitment to their assumed roles and scripts. Furthermore, role-playing groups leave a higher percentage of model-based forecasts unadjusted and when they do make an adjustment, it is significantly less than the groups, whose members are not assigned roles. Differences between the role-playing conditions are interpreted as highlighting the importance of role framing on forecast adjustment and group forecasting behaviour. Future research directions are proposed to improve the accuracy and acceptance of group forecasts.